阅读说明：本技术 具有特定纵横比的多层可溶解固体制品 (Multilayer dissolvable solid article with specific aspect ratio ) 是由 陈鸿兴 罗伯特·韦恩·小格伦 卡尔·戴维·马克纳马拉 黄旭 裴睿智 冈田俊之 于 2019-04-15 设计创作，主要内容包括：本发明题为“具有特定纵横比的多层可溶解固体制品”。这提供了具有特定纵横比的改进的可溶解固体制品。这种可溶解固体制品具有多层结构,该多层结构包括两个或更多个柔性可溶解多孔片材,而所述两个或更多个柔性可溶解多孔片材中的每一个包含水溶性聚合物和表面活性剂,并且特征在于80％至100％的开孔含量百分比并且100μm至2000μm的总平均孔径。多层可溶解固体制品的特征在于最大尺寸D和最小尺寸z；并且其中D/z的比率范围为1至10。(The invention provides a multi-layer dissolvable solid article having a particular aspect ratio. This provides an improved dissolvable solid article having a particular aspect ratio. Such dissolvable solid articles have a multilayer structure comprising two or more flexible dissolvable porous sheets, each of said two or more flexible dissolvable porous sheets comprising a water soluble polymer and a surfactant, and characterized by an open cell content percentage of from 80% to 100% and a total average pore size of from 100 μm to 2000 μm. The multilayer dissolvable solid article is characterized by a maximum dimension D and a minimum dimension z; and wherein the ratio of D/z ranges from 1 to 10.)

1.A dissolvable solid article comprising two or more flexible dissolvable porous sheets, wherein each of said two or more sheets comprises a water soluble polymer and a surfactant and is characterized by a percent open cell content of from 80% to 100% and a total average pore size of from 100 μ ι η to 2000 μ ι η; and wherein the dissolvable solid article is characterized by a maximum dimension D and a minimum dimension z; and wherein the ratio of D/z ranges from 1 to 10.

2. The soluble solid article of claim 1, wherein the ratio of D/z ranges from 1.4 to 9, preferably from 1.5 to 8, more preferably from 2 to 7.

3. The dissolvable solid article according to claim 1 or 2, wherein said smallest dimension z ranges from 3mm to 20cm, preferably from 4mm to 10cm, more preferably from 5mm to 30 mm.

4. The dissolvable solid article according to any one of the preceding claims, wherein each of said two or more sheets is characterized by a thickness in the range of from 0.5mm to 4mm, preferably from 0.6mm to 3.5mm, more preferably from 0.7mm to 3mm, still more preferably from 0.8mm to 2mm, most preferably from 1mm to 1.5 mm.

5. The dissolvable solid article according to any one of the preceding claims, comprising from 4 to 50, preferably from 5 to 40, more preferably from 6 to 30, of said flexible dissolvable porous sheets.

6. The dissolvable solid article according to any one of the preceding claims, wherein said article is characterized by a density in the range of 0.05 grams/cm³To 0.5 g/cm³Preferably 0.06 g/cm³To 0.4 g/cm³More preferably 0.07 g/cm³To 0.2 g/cm³Most preferably 0.08 g/cm³To 0.15 g/cm³。

7. The dissolvable solid article according to any one of the preceding claims, wherein at least one of said two or more flexible dissolvable porous sheets comprises from 10% to 40%, preferably from 15% to 30%, more preferably from 20% to 25%, by total weight of said sheet, of said water soluble polymer; and/or wherein said at least one sheet further comprises from 5% to 80%, preferably from 10% to 70%, more preferably from 30% to 65% of said surfactant by total weight of said sheet.

8. The dissolvable solid article of claim 7, wherein said at least one sheet further comprises from 0.1% to 25%, preferably from 0.5% to 20%, more preferably from 1% to 15%, most preferably from 2% to 12%, by total weight of said sheet, of a plasticizer; and wherein optionally the at least one sheet further comprises one or more additional ingredients selected from: fabric care actives, dishwashing actives, hard surface cleaning actives, cosmetic and/or skin care actives, personal cleansing actives, hair care actives, oral care actives, feminine care actives, baby care actives, and any combination thereof.

9. The dissolvable solid article according to any one of the preceding claims, wherein each of said two or more flexible dissolvable porous sheets is characterized by:

a percentage open cell content of from 85% to 100%, preferably from 90% to 100%; and/or

A total average pore diameter of from 150 μm to 1000 μm, preferably from 200 μm to 600 μm; and/or

An average pore wall thickness of from 5 μm to 200 μm, preferably from 10 μm to 100 μm, more preferably from 10 μm to 80 μm; and/or

A final moisture content of from 0.5% to 25%, preferably from 1% to 20%, more preferably from 3% to 10%, by weight of the article; and/or

A thickness of 0.6mm to 3.5mm, preferably 0.7mm to 3mm, more preferably 0.8mm to 2mm, most preferably 1mm to 1.5 mm; and/or

50 g/m²To 250 g/m²Preferably 80 g/m²To 220 g/m²More preferably 100 g/m²To 200 g/m²Basis weight of (c); and/or

0.05 g/cm³To 0.5 g/cm³Preferably 0.06 g/cm³To 0.4 g/cm³More preferably 0.07 g/cm³To 0.2g/cm³Most preferably 0.08 g/cm³To 0.15 g/cm³(ii) a density of (d); and/or

·0.03m²G to 0.25m²In g, preferably 0.04m²G to 0.22m²G, more preferably 0.05m²G to 0.2m²G, most preferably 0.1m²G to 0.18m²Specific surface area in g.

10. The dissolvable solid article according to any one of the preceding claims, wherein said two or more flexible dissolvable porous sheets comprise a first sheet of a first color and a second sheet of a second, different color, and wherein said first sheet and said second sheet are visible from an exterior surface of said dissolvable solid article.

11. The dissolvable solid article according to claim 10, wherein said first sheet comprises a first benefit agent; wherein the second sheet comprises a second, different benefit agent; and wherein the first color provides a visual cue indicative of the first benefit agent and the second color provides a visual cue indicative of the second benefit agent.

12. The dissolvable solid article according to any one of the preceding claims, comprising at least one functional ingredient located in a central region between two adjacent flexible dissolvable porous sheets, wherein said at least one functional ingredient is selected from the group consisting of a self-cleaning active, a personal care active, and combinations thereof; and wherein the cleaning active is selected from the group consisting of surfactants, free perfumes, encapsulated perfumes, perfume microcapsules, silicones, softeners, enzymes, bleaches, colorants, builders, rheology modifiers, pH adjusters, and combinations thereof; and wherein the personal care active is selected from the group consisting of emollients, humectants, conditioning agents, and combinations thereof.

Technical Field

The present invention relates to an improved dissolvable solid article having a particular aspect ratio.

Background

Flexible dissolvable sheets comprising surfactants and/or other active ingredients in a water soluble polymer carrier or matrix are well known. Such sheets are particularly useful for delivering surfactants and/or other active ingredients when dissolved in water. Such sheets have better structural integrity, are more centralized, and are easier to store, transport, carry, and handle than traditional granular or liquid forms in the same product category. Such sheets are more flexible and less brittle, and have better sensory appeal to consumers than solid tablet forms in the same product category. However, such flexible dissolvable sheets may undergo significantly slow dissolution in water, especially compared to traditional granular or liquid product forms.

To avoid further exacerbating the dissolution problem, such flexible dissolvable sheets have been made relatively thin (i.e., with a high length/width to thickness aspect ratio) and are typically used as separate/single layers. Even if a multilayer structure is provided, the total thickness of such multilayer structure remains relatively thin. The resulting multi-layered structure retains a sheet-like shape, has a high length/width to thickness ratio, may be too floppy or easy to handle, is difficult to separate in use, and is not aesthetically pleasing to consumers.

Accordingly, there is a continuing need for multilayer dissolvable solid articles having improved aspect ratios and/or shapes that are easier to handle and more aesthetically pleasing to consumers, and yet readily dissolve in water.

It would also be advantageous to provide a more cost effective and easily scalable process for preparing the improved multilayer dissolved solid articles described above.

Disclosure of Invention

In one aspect, the present invention provides a dissolvable solid article comprising two or more flexible dissolvable porous sheets, wherein each of said two or more sheets comprises a water soluble polymer and a surfactant, and is characterized by an open cell content percentage of from about 80% to 100%, preferably from about 85% to 100%, more preferably from about 90% to 100%, and a total average pore diameter of from about 100 μ ι η to about 2000 μ ι η, preferably from about 150 μ ι η to about 1000 μ ι η, more preferably from about 200 μ ι η to about 600 μ ι η; wherein the dissolvable solid article is characterized by a maximum dimension D and a minimum dimension z; and wherein the ratio of D/z ranges from 1 to about 10, preferably from about 1.4 to about 9, more preferably from about 1.5 to about 8, most preferably from about 2 to about 7.

Preferably, the smallest dimension z of such dissolvable solid articles ranges from about 3mm to about 20cm, preferably from about 4mm to about 10cm, more preferably from about 5mm to about 30 mm.

More preferably, each of the two or more flexible dissolvable porous sheets described above is characterized by a thickness in the range of from about 0.5mm to about 4mm, preferably from about 0.6mm to about 3.5mm, more preferably from about 0.7mm to about 3mm, still more preferably from about 0.8mm to about 2mm, most preferably from about 1mm to about 1.5 mm. The dissolvable solid article of the present invention may comprise from about 4 to about 50, preferably from about 5 to about 40, more preferably from about 6 to about 30 such flexible dissolvable porous sheets.

The dissolvable solid article may have a range of about 0.05 grams/cm³To about 0.5 g/cm³Preferably about 0.06 g/cm³To about 0.4 g/cm³And more preferably about 0.07 g/cm³To about 0.2 g/cm³And most preferably about 0.08 g/cm³To about 0.15 g/cm³Inner density.

In a preferred embodiment, at least one of the flexible dissolvable porous sheets comprises from about 10% to about 40%, preferably from about 15% to about 30%, more preferably from about 20% to about 25% by total weight of the sheet of the water soluble polymer described above and/or from about 5% to about 80%, preferably from 10% to 70%, more preferably from 30% to 65% by total weight of the sheet of the surfactant described above. Further, the at least one sheet may comprise from about 0.1% to about 25%, preferably from about 0.5% to about 20%, more preferably from about 1% to about 15%, most preferably from about 2% to about 12% of a plasticizer by total weight of the sheet. Additionally, the at least one sheet may comprise one or more additional ingredients selected from the group consisting of: fabric care actives, dishwashing actives, hard surface cleaning actives, cosmetic and/or skin care actives, personal cleansing actives, hair care actives, oral care actives, feminine care actives, baby care actives, and any combination thereof.

It is particularly preferred that each of the flexible dissolvable porous sheets in the dissolvable solid article of the present invention is characterized by one or more of the following parameters:

an average pore wall thickness of from about 5 μm to about 200 μm, preferably from about 10 μm to about 100 μm, more preferably from about 10 μm to about 80 μm; and/or

A final moisture content of from about 0.5% to about 25%, preferably from about 1% to about 20%, more preferably from about 3% to about 10%, by weight of the sheet; and/or

About 50 g/m²To about 250 g/m²Preferably about 80 g/m²To about 220 g/m²And more preferably about 100 grams/m²To about 200 g/m²Basis weight of (c); and/or

About 0.05 g/cm³To about 0.5 g/cm³Preferably about 0.06 g/cm³To about 0.4 g/cm³And more preferably about 0.07 g/cm³To about 0.2 g/cm³And most preferably about 0.08 g/cm³To about 0.15 g/cm³(ii) a density of (d); and/or

About 0.03m²G to about 0.25m²A/g, preferably about 0.04m²G to about 0.22m²Per g, more preferably about 0.05m²G to about 0.2m²G, most preferably about 0.1m²G to about 0.18m²Specific surface area in g.

These and other aspects of the invention will become more apparent upon reading the following detailed description of the invention.

Drawings

Figure 1 illustrates a multilayer dissolvable solid article according to one embodiment of the present invention.

Figure 2 illustrates a prior art convection-based heating/drying apparatus for making flexible porous dissolvable solid sheets in a batch process.

Figure 3 illustrates a prior art microwave-based heating/drying apparatus for making flexible porous dissolvable solid sheets in a batch process.

Figure 4 shows a prior art impingement oven based heating/drying apparatus for making flexible porous dissolvable solid sheets in a continuous process.

Figure 5 shows a bottom conduction based heating/drying apparatus for making the flexible porous dissolvable sheet of the present invention in a batch process, according to one embodiment of the present invention.

Figure 6 shows a rotary drum based heating/drying apparatus for making another flexible porous dissolvable sheet of the present invention in a continuous process, according to another embodiment of the present invention.

Fig. 7A shows a Scanning Electron Microscope (SEM) image of the top surface of a flexible porous dissolvable sheet of the present invention containing fabric care actives prepared by a process employing a rotating drum based heating/drying apparatus. Fig. 7B shows an SEM image of the top surface of a comparative flexible porous dissolvable sheet containing the same fabric care actives as the sheet shown in fig. 7A, prepared by a method employing an impingement oven based heating/drying apparatus.

Fig. 8A shows an SEM image of the top surface of a flexible porous dissolvable sheet of the invention containing hair care actives prepared by a process employing a bottom conduction based heating/drying apparatus. Fig. 8B shows an SEM image of the top surface of a comparative flexible porous dissolvable sheet containing the same hair care actives as the sheet shown in fig. 8A, prepared by a method employing an impingement oven based heating/drying apparatus.

Detailed Description

I. Definition of

The term "dissolvable" as used herein refers to the ability of an article to completely or substantially dissolve in sufficient deionized water to leave less than 5 wt.% undissolved residue within eight (8) hours at 20 ℃ and atmospheric pressure without any agitation.

The term "solid" as used herein refers to the ability of an article to substantially retain its shape (i.e., without any visible change in its shape) at 20 ℃ and atmospheric pressure when the article is unconstrained and no external force is applied thereto.

The term "flexible" as used herein refers to the ability of an article to withstand stress without breaking or significantly cracking when the article is bent 90 ° along a centerline perpendicular to its longitudinal direction. Preferably, such articles can undergo significant elastic deformation and are characterized by a young's modulus of no greater than 5GPa, preferably no greater than 1GPa, more preferably no greater than 0.5GPa, most preferably no greater than 0.2 GPa.

The term "sheet" as used herein refers to a non-fibrous structure having a three-dimensional shape, i.e., having a thickness, a length, and a width, with both the length-thickness aspect ratio and the width-thickness aspect ratio being at least about 5:1, and the length-width ratio being at least about 1: 1. Preferably, the length-thickness aspect ratio and the width-thickness aspect ratio are each at least about 10:1, more preferably at least about 15:1, most preferably at least about 20: 1; and the length-to-width aspect ratio is preferably at least about 1.2:1, more preferably at least about 1.5:1, and most preferably at least about 1.618: 1.

The term "water-soluble" as used herein refers to the ability of a sample material to completely dissolve or disperse into water without leaving visible solids or forming a distinct separate phase when at least about 25 grams, preferably at least about 50 grams, more preferably at least about 100 grams, most preferably at least about 200 grams of such material are placed in 1 liter (1L) of deionized water at 20 ℃ and thoroughly stirred at atmospheric pressure.

The term "open-cell foam" or "open-cell pore structure" as used herein refers to a solid, interconnected matrix comprising a polymer that defines a network of spaces or cells that contain a gas, typically a gas (e.g., air), and which does not collapse during the drying process, thereby maintaining the physical strength and cohesion of the solid. The interconnectivity of the structure can be described by the percent open cell content, which is measured by test 3 disclosed below.

As used herein, the term "bottom surface" refers to the surface of the flexible, porous, dissolvable solid sheet of the present invention that directly contacts the support surface on which the aerated wet premix sheet is placed during the drying step. The term "top surface" refers to the surface of the sheet opposite the bottom surface. Further, such a solid sheet may be divided into three (3) regions along its thickness, including a top region adjacent its top surface, a bottom region adjacent its bottom surface, and a middle region located between the top and bottom regions. The top, middle and bottom regions have the same thickness, i.e., each region has a thickness of about 1/3 a, which is the total thickness of the sheet.

The terms "aerated", "aerated" or "aerated" as used herein refer to a process in which a gas is introduced into a liquid or paste-like composition by mechanical and/or chemical means.

The term "heating direction" as used herein refers to the direction in which a heat source applies thermal energy to an article, which results in a temperature gradient in such articles decreasing from one side of such articles to the other. For example, if a heat source located on one side of an article applies thermal energy to the article to produce a temperature gradient that decreases from the one side to an opposite side, the direction of heating is considered to extend from the one side to the opposite side. If both sides of such an article or different portions of such an article are heated simultaneously without an observable temperature gradient across such an article, the heating occurs in a non-directional manner and there is no direction of heating.

The term "substantially opposite" or "substantially offset" as used herein refers to two directions or two lines having an offset angle of 90 ° or more therebetween.

The terms "substantially aligned" or "substantially aligned" as used herein refer to two directions or two lines having an offset angle of less than 90 ° therebetween.

The term "primary heat source" as used herein refers to a heat source that provides more than 50%, preferably more than 60%, more preferably more than 70%, most preferably more than 80% of the total heat energy absorbed by the subject (e.g., the sheet of aerated wet premix according to the present invention).

The term "controlled surface temperature" as used herein refers to a surface temperature that is relatively consistent, i.e., less than +/-20% fluctuation, preferably less than +/-10% fluctuation, more preferably less than +/-5% fluctuation.

The term "substantially free" or "substantially free" means that the indicated material is not intentionally added to the composition or product, and is present in the composition or product in an extremely low amount; alternatively, it is preferred that it is present in such compositions or products in an amount that is undetectable analytically. It may include compositions or products in which the indicated material is present only as an impurity of one or more materials intentionally added to such compositions or products.

Conventional dissolvable solid articles have a relatively high length/width-to-thickness ratio, i.e., they are relatively thin, to ensure that these articles dissolve rapidly in water. Accordingly, such dissolvable solid articles are typically provided in the form of relatively large but thin sheet products that may be difficult to handle (e.g., too floppy and prone to sticking together and difficult to separate upon use) and aesthetically unpleasing to consumers. However, there is little or no room to change or improve the product form due to the limitations imposed by the dissolution requirements.

The surprising and unexpected discovery of the present invention is that the three-dimensional multilayer structure formed by stacking together the multilayer flexible dissolvable porous solid sheet of the present invention having an open cell foam or OCF structure defined by a percentage of open cell content of about 80% to 100% and a total average pore size of about 100 μm to about 2000 μm is more soluble than a single layer structure having the same aspect ratio. This allows the resulting dissolvable solid article to extend significantly in the thickness direction to create a three-dimensional product shape that is easier to handle and more aesthetically pleasing to the consumer (e.g., a product in the form of a thick mat or even a cube).

Specifically, fig. 1 shows a multilayer dissolvable solid article 1 formed by stacking together multiple layers of the above-described flexible dissolvable porous sheets 2,4, 6, and 8, characterized by a maximum dimension D and a minimum dimension z (perpendicular to the maximum dimension D), with the ratio of D/z (hereinafter also referred to as the "aspect ratio") being in the range of 1 to about 10, preferably about 1.4 to about 9, preferably about 1.5 to about 8, more preferably about 2 to about 7.

The multi-layered dissolvable solid article of the present invention may have any suitable shape, regular or irregular, such as spherical, cubic, rectangular, polygonal, elliptical, cylindrical, rod-shaped, sheet-shaped, flower-shaped, fan-shaped, star-shaped, disc-shaped, and the like. The hexagonal dissolvable solid article 1 shown in fig. 1 has an aspect ratio of about 5.8 to 6. When the aspect ratio is 1, the dissolvable solid article has a spherical shape. When the aspect ratio is about 1.4, the dissolvable solid article has a cubic shape.

The multilayer dissolvable solid article of the present invention may have a minimum dimension z of greater than about 3mm but less than about 20cm, preferably from about 4mm to about 10cm, more preferably from about 5mm to about 30 mm.

The multilayer dissolvable solid article described above may comprise more than two such flexible dissolvable porous sheets. For example, it may comprise from about 4 to about 50, preferably from about 5 to about 40, more preferably from about 6 to about 30 of said flexible dissolvable porous sheets. The improved OCF structure in the flexible dissolvable porous sheet prepared according to the present invention allows for stacking many sheets (e.g., 15 to 40) together while still providing a satisfactory overall dissolution rate for the stack.

In a particularly preferred embodiment of the invention, the multilayer dissolvable solid article comprises 15 to 40 layers of the above-described flexible dissolvable porous sheet, and has an aspect ratio of from about 2 to about 7.

The following is a detailed description of the formulations and methods for making such flexible dissolvable porous sheets, and methods for assembling them into the multilayer dissolvable solid articles of the invention.

Overview of the Process for preparing sheets

WO2010077627 discloses a batch process for forming a porous sheet having an Open Cell Foam (OCF) structure, characterized by an open cell content percentage of about 80% to 100%, for improved dissolution. Specifically, a premix of the raw materials is first formed, vigorously aerated, and then dried by batch heating (e.g., in a convection oven or microwave oven) to form a porous sheet having the desired OCF structure. While this OCF structure significantly improves the dissolution rate of the resulting porous sheet, there is still a significantly denser and less porous bottom region with thicker cell walls in this sheet. Such a high density bottom region may negatively affect the flow of water through the sheet, which may adversely affect the overall dissolution rate of the sheet. The "barrier" effect of multiple high density bottom regions is particularly enhanced when multiple such sheets are stacked together to form a multilayer structure.

WO2012138820 discloses a similar process as WO2010077627, except that continuous drying of the aerated wet premix is achieved by using e.g. an impingement oven (instead of a convection oven or a microwave oven). OCF sheets formed by such continuous drying processes are characterized by improved uniformity/consistency of pore structure across different regions thereof. Unfortunately, rate limiting factors such as a top surface with relatively small pore openings and a top region with relatively small pores (i.e., a shell-like top region) still exist in such OCF sheets, which can negatively impact the flow of water therethrough and slow its dissolution.

In the drying step of the above method, the OCF structure is formed under simultaneous mechanisms of water evaporation, bubble collapse, interstitial liquid drainage from the thin film bubble facing to the plateau boundary between bubbles (creating openings between bubbles and forming open pores), and solidification of the premix. Various processing conditions may affect these mechanisms, such as the solids content in the wet premix, the viscosity of the wet premix, gravity and drying temperature, and the need to balance these processing conditions to achieve controlled drainage and formation of the desired OCF structure.

It is a surprising and unexpected discovery of the present invention that, in addition to the processing conditions described above, the direction of the thermal energy employed during the drying step (i.e., the direction of heating) can also have a significant effect on the resulting OCF structure.

For example, if thermal energy is applied in a non-directional condition (i.e., without a definite heating direction) during the drying step, or if the heating direction is substantially aligned with the direction of gravity (i.e., has an offset angle of less than 90 ° between them) during most of the drying step, the resulting flexible porous dissolvable solid sheet tends to have a top surface with smaller pore openings and larger pore size variations in different regions along the direction across its thickness. Conversely, when the heating direction deviates from the direction of gravity (i.e., has a deviation angle of 90 ° or greater therebetween) during most of the drying step, the resulting solid sheet may have a top surface with larger pore openings and reduced pore size variations in different regions along the direction across the thickness of such sheet. Accordingly, the latter sheet receives the water flowing therethrough more easily and is therefore more soluble than the former sheet.

While not being bound by any theory, it is believed that the alignment or misalignment between the direction of heating and the direction of gravity during the drying step, and its duration, can significantly affect interstitial liquid drainage between bubbles and, correspondingly, pore expansion and pore opening in the solidified premix and produce solid sheets with very different OCF structures. This difference is more clearly illustrated by figures 2 to 5 below.

Fig. 2 shows a prior art convection-based heating/drying apparatus. During the drying step, the mould 10 (which may be made of any suitable material, such as metal, ceramic orMade) is filled with an aerated wet premix that forms a sheet 12 having a first side 12A (i.e., a top side) and an opposite second side 12B (i.e., a bottom side because it is in direct contact with the support surface of the mold 10). During the drying step, such a mold 10 is placed in a convection oven at 130 ℃ for about 45 to 46 minutes. The convection oven heats the sheet 12 from above, i.e., heats the sheet 12 in a downward heating direction (as indicated by the cross-hatched arrows) that creates a decreasing temperature gradient in the sheet 12 from a first side 12A to an opposite second side 12B. The downward heating direction coincides with the direction of gravity (as indicated by the white arrows) and this aligned position is maintained throughout the drying time. During drying, gravity drains the liquid premix down towards the bottom zone, while the downward heating direction dries the top zone first and the bottom zone last. Thus, the porous solid sheet is formed with a top surface containing many pores with small openings formed by gas bubbles that have no chance of fully expanding. Such a top surface with smaller pore openings is not optimal for water to enter the sheet, which may limit the dissolution rate of the sheet. On the other hand, the bottom region of such a sheet is dense and less porous, with larger pores formed by fully expanded gas bubbles, but in very small numbers, and the walls of the pores between the pores in such a bottom region are thick, due to downward liquid drainage caused by gravity. This dense bottom zone with fewer pores and thick cell walls is a further rate-limiting factor for the overall dissolution rate of the sheet.

Figure 3 shows a prior art microwave-based heating/drying apparatus. During the drying step, the mold 30 is filled with an aerated wet premix that forms a sheet 32 having a first side 32A (top side) and an opposite second side 32B (bottom side). Such a mold 30 is then placed in a low energy density microwave applicator (not shown) supplied by industrial microwave systems, inc. of north carolina and operated at a power of 2.0kW, a belt speed of 1 foot/minute, and an ambient air temperature of 54.4 ℃. During the drying step, the mold 30 is placed in such a microwave application for about 12 minutes. Such microwave applicators heat the sheet 32 from within without any definite or consistent heating direction. Accordingly, no temperature gradient is formed in the sheet 32. During drying, the entire sheet 32 is heated at the same time, or nearly the same time, while gravity (as indicated by the white arrows) still drains the liquid premix down toward the bottom region. As a result, the cured sheet so formed has more evenly distributed and uniformly sized pores as compared to sheets formed by convection-based heating/drying devices. However, liquid drainage under gravity during the microwave-based drying step may still result in a dense bottom region with thick pore walls. Further, during the drying step, heating the entire sheet 32 at the same time may still limit pore expansion and pore opening on the top surface, and the resulting sheet may still have a top surface with relatively small pore openings. In addition, the microwave energy heats and boils water within the sheet 32, which may generate irregularly sized bubbles and form unintended dense areas with thick cell walls.

Figure 4 shows a prior art impingement oven based heating/drying apparatus. During the drying step, the mold 40 is filled with an aerated wet pre-mix that forms a sheet 42 having a first side 42A (top side) and an opposite second side 42B (bottom side). This mould 40 is then placed in a continuous impingement oven (not shown) under conditions similar to those described in table 2 of example 1 of WO 2012138820. This continuous impingement oven heats sheet 42 from both the top and bottom in opposite and offset heating directions (shown by the two cross-hatched arrows). Accordingly, no significant temperature gradient is formed in the sheet 42 during drying, and the entire sheet 42 is heated from both its top and bottom surfaces at approximately the same time. Similar to the microwave-based heating/drying apparatus described in fig. 3, in such an impingement oven-based heating/drying apparatus of fig. 4, gravity (as indicated by the white arrows) continues to drain the liquid pre-mixture downward toward the bottom region. As a result, the cured sheet so formed has more evenly distributed and uniformly sized pores as compared to sheets formed by convection-based heating/drying devices. However, liquid drainage under gravity during the drying step may still result in a dense bottom region with thick pore walls. Further, heating the sheet 42 from both sides at approximately the same time during the drying step may still limit pore expansion and pore opening on the top surface, and the resulting sheet may still have a top surface with relatively small pore openings.

In contrast to the above-described prior art heating/drying devices, the present invention provides a heating/drying device for drying an aerated wet premix, wherein the heating direction is purposefully configured to counteract/reduce liquid drainage towards the bottom region caused by gravity (thereby reducing density and improving pore structure in the bottom region) and allow more time for bubbles near the top surface to expand during drying (thereby forming significantly larger pore openings on the top surface of the resulting sheet). Both of these features serve to increase the overall dissolution rate of the sheet and are therefore desirable.

Figure 5 illustrates a bottom conduction based heating/drying apparatus for making the flexible porous dissolvable sheet of the present invention, according to one embodiment of the present invention. Specifically, the mold 50 is filled with an aerated wet pre-mix that forms a sheet 52 having a first side 52A (i.e., a bottom side) and an opposite second side 52B (i.e., a top side). During the drying step, such a mold 50 is placed on a heated surface (not shown), for example, on top of a preheated peltier plate having a controlled surface temperature of about 125 ℃ to 130 ℃ for about 30 minutes. Heat is conducted through the die from a heated surface at the bottom of the die 50 to heat the sheet 52 from below, i.e., in an upward heating direction (as indicated by the cross-hatched arrows), which creates a temperature gradient in the sheet 52 that decreases from a first side 52A (bottom side) to an opposite second side 52B (top side). This upward heating direction is opposite to the direction of gravity (as indicated by the white arrow) and remains so throughout the drying time (i.e., the heating direction is opposite to the direction of gravity for almost 100% of the drying time). During drying, gravity still drains the liquid premix down toward the bottom zone. However, the upward heating direction dries the sheet from the bottom up, and water vapor generated by heat at the bottom region is generated upward to escape from the solidification matrix, so downward liquid drainage toward the bottom region is significantly limited and "counteracted"/reduced by the solidification matrix and the rising water vapor. Accordingly, the bottom region of the resulting dried sheet is less dense and contains many pores with relatively thin pore walls. Furthermore, because the top region is the last region to be dried during the process, the bubbles in the top region have sufficient time to expand to form significantly larger open pores at the top surface of the resulting sheet, which is particularly effective in promoting water entry into the sheet. In addition, the resulting sheet has a more uniform distribution of total pore sizes in different regions (e.g., top, middle, bottom) of the sheet.

Figure 6 shows a rotating drum based heating/drying apparatus for making the flexible porous dissolvable sheet of the present invention, according to another embodiment of the present invention. Specifically, the feed tank 60 is filled with an aerated wet premix 61. A heated rotatable drum 70 (also referred to as a drum dryer) is placed above the feed chute 60. The heated drum dryer 70 has a cylindrical heated outer surface characterized by a controlled surface temperature of about 130 c and is rotated in a clockwise direction (as shown by the thin curve with arrows) to pick up the aerated wet pre-mixture 61 from the feed chute 60. The aerated wet pre-mixture 61 forms a sheet 62 over the cylindrical heated outer surface of the tumble dryer 70, which spins and dries the sheet 62 of this aerated wet pre-mixture in approximately 10 to 15 minutes. Leveling blades (not shown) may be placed near the slurry pick-up location to ensure consistent thickness of the sheet 62 so formed, although the thickness of the sheet 62 may be controlled simply by adjusting the viscosity of the aerated wet pre-mix 61 and the rotational speed and surface temperature of the drum dryer 70. Once dried, the web 62 may then be picked up at the end of the drum rotation, either manually or by a doctor blade 72.

As shown in fig. 6, the sheet 62 formed from the aerated wet pre-mixture 61 includes a first side 62A (i.e., bottom side) and an opposite second side 62B (i.e., top side) that directly contact the heated outer surface of the heated drum dryer 70. Accordingly, heat from the drum dryer 70 is conducted to the sheet 62 in an outward heating direction to first heat a first side 62A (bottom side) of the sheet 62 and then heat an opposite second side 62B (top side). This outward heating direction creates a temperature gradient in the sheet 62 that decreases from a first side 62A (bottom side) to an opposite second side 62B (top side). As the drum dryer 70 rotates, the outward heating direction changes slowly and constantly, but follows a very clear and predictable path (as indicated by the plurality of outwardly extending cross-hatched arrows in fig. 6). The relative positions of the outward heating direction and the gravitational direction (as indicated by the white arrows) also slow down and change in a similar clear and predictable manner. For less than half of the drying time (i.e., when the heating direction is below the horizontal dashed line), the outward heating direction is substantially aligned with the direction of gravity, with an offset angle therebetween of less than 90 °. During most of the drying time (i.e., when the heating direction is flush with or above the dashed horizontal line), the outward heating direction is opposite or substantially opposite to the direction of gravity, with an offset angle of 90 ° or greater therebetween. Depending on the initial "start" coating position of the web 62, the heating direction may be opposite or substantially opposite to the direction of gravity for more than 55% of the drying time (if the coating starts at the very bottom of the drum dryer 70), preferably more than 60% of the drying time (if the coating starts at a higher position of the drum dryer 70, as shown in fig. 6). Thus, in most drying steps, in a rotary drum based heating/drying apparatus, such slowed rotation and altered heating direction may still serve to limit and "counteract"/reduce liquid drainage in the sheet 62 caused by gravity, resulting in improved OCF structure in the sheet so formed. The resulting sheet dried by heated drum dryer 70 is also characterized by a less dense bottom region having many more uniformly sized pores and a top surface having relatively larger pore openings. In addition, the resulting sheet has a more uniform distribution of total pore sizes in different regions (e.g., top, middle, bottom) of the sheet.

In addition to employing the desired direction of heating (i.e., a substantially offset relationship with respect to the direction of gravity) as described above, it may be desirable and even important to carefully adjust the viscosity and/or solids content of the wet pre-mix, the aeration amount and aeration rate (air feed pump speed, mix head speed, air flow rate, density of the aerated pre-mix, etc., which may affect the size and number of air bubbles in the aerated pre-mix and correspondingly affect the pore size/distribution/number/character in the cured sheet), drying temperature, and drying time in order to achieve the optimum OCF structure in the resulting sheet according to the present invention.

A more detailed description of the process for making the flexible porous dissolvable sheet according to the present invention, as well as the physical and chemical characteristics of such sheet, is provided in the ensuing sections.

The method of the present invention for producing a solid sheet

The present invention provides a new and improved process for making a flexible porous dissolvable solid sheet comprising the steps of: (a) forming a premix containing the raw materials (e.g., water-soluble polymer, active ingredient such as surfactant, and optional plasticizer) dissolved or dispersed in water or suitable solvent, characterized by a temperature of about 40 ℃ and 1s^-1A viscosity of about 1,000cps to about 25,000 cps; (b) aerating the premix (e.g., by introducing a gas into the wet slurry) to form an aerated wet premix; (c) forming the aerated wet pre-mix into a sheet having opposing first and second sides; and (d) drying the formed sheet at a temperature of 70 ℃ to 200 ℃ along a heating direction that forms a temperature gradient that decreases from the first side to the second side of the formed sheet for a drying time of 1 minute to 60 minutes, wherein the heating direction substantially deviates from the gravity direction for more than half of the drying time, i.e. the drying step is performed under heating along a majority of the "antigravity" heating direction.This primary "antigravity" heating direction can be achieved in a variety of ways, including but not limited to bottom conduction-based heating/drying devices and rotary drum-based heating/drying devices, as shown above in fig. 5 and 6, respectively.

Step (A): preparation of Wet premix

The wet premixes of the invention are typically prepared by mixing the target solids (comprising water-soluble polymer, surfactant and/or other benefit agents, optional plasticizer, and other optional ingredients) with a sufficient amount of water or other solvent in the premix tank. A mechanical mixer may be used to form the wet premix. Mechanical mixers useful herein include, but are not limited to, pitched blade turbines or MAXBLEND mixers (Sumitomo Heavy Industries).

Of particular importance in the present invention is the adjustment of the viscosity of the wet premix so that it is at 40 ℃ and 1s^-1In a predetermined range of about 1,000cps to about 25,000cps when measured as follows. In the subsequent drying step, the viscosity of the wet premix has a significant effect on the pore expansion and pore opening of the aerated premix, and wet premixes with different viscosities can form flexible porous dissolvable solid sheets with very different foam structures. In one aspect, when the wet premix is too thick/viscous (e.g., such as at 40 ℃ and 1 s)^-1Having a viscosity of greater than about 25,000 cps) aeration of such wet premixes may become more difficult. More importantly, interstitial liquid drainage from the film blister face to the plateau boundary of the three-dimensional foam during the subsequent drying step may be adversely affected or significantly limited. Interstitial liquid drainage during drying is believed to be critical to achieving pore expansion and pore opening in the aerated wet premix during the subsequent drying step. As a result, the flexible porous dissolvable solid sheets formed therefrom may have significantly smaller pores and less interconnectivity between pores (i.e., pores that are more "closed" than open pores), which makes it more difficult for water to enter and exit such sheets. On the other hand, when the wet premix is too thin/inoperable (e.g., as at 40 ℃ and 1 s)^-1Viscosity below about 1,000cps, measured below), aerated wet pre-mixThe premix may not be sufficiently stable, i.e., the air bubbles in the wet premix may collapse, or coalesce too quickly after aeration and before drying. Thus, the resulting solid sheet may be much smaller and denser than desired porosity.

In one embodiment, e.g., at 40 ℃ and 1s^-1The viscosity of the wet pre-mix ranges from about 3,000cps to about 24,000cps, preferably from about 5,000cps to about 23,000cps, more preferably from about 10,000cps to about 20,000cps, measured as follows. Premix viscosity values were measured using a Malvern Kinexus Lab + rheometer with a cone-plate geometry (CP1/50SR3468 SS), a gap width of 0.054mm, a temperature of 40 ℃ and a shear rate of 1.0 reciprocal seconds for a period of 360 seconds.

In preferred, but not necessary, embodiments, the target solids are present in the wet premix at a level of from about 15% to about 70%, preferably from about 20% to about 50%, more preferably from about 25% to about 45%, by total weight of the wet premix. The percent solids content is the sum of the weight percentages of all solid components, semi-solid components, and liquid components other than water and any significant volatile species, such as low boiling alcohols, by weight of the total processing mixture. On the one hand, if the solids content in the wet pre-mix is too high, the viscosity of the wet pre-mix may increase to a level that will prevent or adversely affect interstitial liquid drainage and prevent the formation of the desired predominantly open-celled porous solid structure as described herein. On the other hand, if the solids content in the wet premix is too low, the viscosity of the wet premix may decrease to a level that will result in bubble collapse/coalescence and more shrinkage percentage (%) of the pore structure during drying, which results in a solid sheet with significantly lower porosity and density.

In the target solids in the wet premixes of the invention, there may be from about 1% to about 75% surfactant, from about 0.1% to about 25% water-soluble polymer, and optionally from about 0.1% to about 25% plasticizer, by total weight of solids. Other actives or benefit agents may also be added to the premix.

Optionally, the wet pre-mix is immediately preheated prior to and/or during the aeration process at a temperature above ambient temperature but below any temperature that would cause degradation of the components therein. In one embodiment, the wet pre-mix is maintained at an elevated temperature in the range of from about 40 ℃ to about 100 ℃, preferably from about 50 ℃ to about 95 ℃, more preferably from about 60 ℃ to about 90 ℃, and most preferably from about 75 ℃ to about 85 ℃. In one embodiment, optional continuous heating is used prior to the aeration step. In addition, additional heat may be applied during aeration in an attempt to maintain the wet pre-mixture at such elevated temperatures. This may be achieved by conductive heating from one or more surfaces, injection of steam, or other treatment means. It is believed that the act of pre-heating the wet pre-mix prior to and/or during the aeration step may provide a means for reducing the viscosity of the pre-mix containing a higher percentage of solids content for improved incorporation of gas bubbles into the mixture and formation of the desired solid sheet. Higher percent solids are desirable because they can reduce the overall energy requirements for drying. Thus, an increase in the percent solids may conversely result in a decrease in the level of water and an increase in viscosity. As noted above, a wet premix with too high a viscosity is undesirable for the practice of the present invention. Preheating can effectively offset this viscosity increase, thus allowing the manufacture of rapidly dissolving sheets even when high solids content premixes are used.

Step (B): aeration of wet premixes

Aeration of the wet premix is conducted so as to introduce a sufficient amount of gas bubbles into the wet premix for subsequent formation of OCF structures therein upon drying. Once fully aerated, the wet premix is characterized by a density that is significantly lower than that of either an unaerated wet premix (which may contain some inadvertently trapped air bubbles) or an insufficiently aerated wet premix (in which some air bubbles may be contained but the volume percentage is much lower and the bubble size is significantly larger). Preferably, the aerated wet premix has a density in the range of from about 0.05g/ml to about 0.5g/ml, preferably from about 0.08g/ml to about 0.4g/ml, more preferably from about 0.1g/ml to about 0.35g/ml, still more preferably from about 0.15g/ml to about 0.3g/ml, most preferably from about 0.2g/ml to about 0.25 g/ml.

Aeration may be accomplished by physical or chemical means in the present invention. In one embodimentThe gas may be introduced into the wet premix by mechanical agitation, for example, by using any suitable mechanical processing apparatus, including but not limited to: a rotor-stator mixer, a planetary mixer, a pressurized mixer, a non-pressurized mixer, a batch mixer, a continuous mixer, a semi-continuous mixer, a high shear mixer, a low shear mixer, a submerged distributor, or any combination thereof. In another embodiment, it may be achieved by chemical means, for example, by providing in situ gas formation by chemical reaction of one or more ingredients using a chemical blowing agent, including carbon dioxide (CO) formation by an effervescent system₂Gas).

In a particularly preferred embodiment, it has been found that aeration of the wet premix can be achieved cost effectively by using a continuous pressurized aerator or mixer conventionally used in the production of marshmallow in the food industry. Continuous pressurized mixers can be used to homogenize or aerate the wet premix to produce a highly uniform and stable foam structure with uniform bubble size. The unique design of the high shear rotor/stator mixing head can produce uniform bubble size in the layer of open cell foam. Suitable continuous pressurized aerators or mixers include Morton mixers (Morton Machine Co., Motherwell, Scotland), Oakes continuous automatic mixers (E.T. Oakes Corporation, Hauppauge, New York), Fedco continuous mixers (The Peer Group, Sidney, Ohio), Mondo (Haas-Mondomix B.V., Netherlands), Aeros (Aeros Industrial Equipment Co., Ltd., Guangdong Provision, China), and Presshirp (Hosokawa Micron Group, Osaka, Japan). For example, the Aeros A20 continuous aerator may be operated at a feed pump speed setting of about 300 to 800 (preferably about 500 to 700), with a mix head speed setting of about 300 to 800 (preferably about 400 to 600), respectively, and an air flow rate of about 50 to 150 (preferably 60 to 130, more preferably 80 to 120). As another example, the Oakes continuous automatic mixer may be operated at a mix head speed setting of about 10rpm to 30rpm (preferably about 15rpm to 25rpm, more preferably about 20rpm) with an air flow rate of about 10 liters/hour to 30 liters/hour (preferably about 15L/hour to 25L/hour, more preferably about 19L/hour to 20L/hour).

In another specific embodiment, aeration of the wet pre-mixture may be achieved by using a spinning rod as part of a rotary drum dryer, more specifically a feed chute, wherein the wet pre-mixture is stored before it is coated onto the heated outer surface of the drum dryer and dried. The spinning bar is typically used to agitate the wet pre-mix to prevent phase separation or settling in the feed tank during the waiting time before it is applied to the heated rotating drum of the drum dryer. In the present invention, such spinning bars may be operated at a rotational speed in the range of from about 150rpm to about 500rpm, preferably from about 200rpm to about 400rpm, more preferably from about 250rpm to about 350rpm, to mix the wet pre-mix at the air interface and provide sufficient mechanical agitation required to achieve the desired aeration of the wet pre-mix.

As described above, the wet pre-mix may be maintained at an elevated temperature during aeration to adjust the viscosity of the wet pre-mix for optimal aeration and control of drainage during drying. For example, when aeration is achieved by a spinning bar using a rotating drum, the aerated wet premix in the feed tank is typically maintained at about 60 ℃ during the initial aeration by the spinning bar (when the rotating drum is stationary). Then, when the rotating drum is heated and starts to rotate, it is heated to about 70 ℃.

The bubble size of the aerated wet premix helps to obtain a uniform layer in the OCF structure of the resulting solid sheet. In one embodiment, the aerated wet premix has a bubble size of from about 5 microns to about 100 microns; and in another embodiment, the bubble size is from about 20 microns to about 80 microns. The uniformity of bubble size results in a consistent density of the resulting solid sheet.

Step (C): sheet forming

After sufficient aeration, the aerated wet premix is formed into one or more sheets having opposing first and second sides. The sheet forming step may be performed in any suitable manner, such as by extrusion, casting, molding, vacuum forming, pressing, printing, coating, and the like. More specifically, the aerated wet premix may be formed into a sheet by: (i) casting it into shallow cavities or trays orSpecially designed sheet die; (ii) extruding it onto a continuous belt or screen of a dryer; (iii) it is coated on the outer surface of a rotary drum dryer. Preferably, the support surface on which the sheet is formed from or coated with: corrosion resistant materials, non-interactive and/or non-adherent materials, such as metals (e.g., steel, chromium, etc.), metals (e.g., stainless steel, etc.), metals (,Polycarbonate, a,HDPE, LDPE, rubber, glass, etc.

Preferably, the sheet of aerated wet premix formed has a thickness in the range of from 0.5mm to 4mm, preferably from 0.6mm to 3.5mm, more preferably from 0.7mm to 3mm, still more preferably from 0.8mm to 2mm, most preferably from 0.9mm to 1.5 mm. Controlling the thickness of such formed sheets of aerated wet premix may be important to ensure that the resulting solid sheets have the desired OCF structure. If the formed sheet is too thin (e.g., less than 0.5mm thick), many of the air bubbles trapped in the aerated wet pre-mix will expand during the subsequent drying step to form through-holes extending through the entire thickness of the resulting solid sheet. If too many, such through-holes may significantly compromise both the overall structural integrity and aesthetic appearance of the sheet. If the formed sheet is too thick, it not only takes longer to dry, but it can also result in a solid sheet with a larger pore size variation between different regions (e.g., top, middle, and bottom regions) along its thickness, because the longer the drying time, the more imbalance of forces that can occur through bubble collapse/coalescence, liquid drainage, pore expansion, pore opening, water evaporation, etc.

More importantly, it is easier to assemble multiple layers of relatively thin sheets into a multilayer structure of the present invention having a desired aspect ratio, while still providing a satisfactory pore structure to dissolve quickly and ensure effective drying in a relatively short drying time.

Step (D): drying under antigravity heating

A key feature of the present invention is the use of a countergravity heating direction during the drying step, either through the entire drying time or at least through more than half of the drying time. Without being bound by any theory, it is believed that such counter-gravity heating direction may reduce or counteract excess interstitial liquid drainage towards the bottom region of the formed sheet during the drying step. Furthermore, because the top surface is finally dried, a longer time is allowed for the bubbles near the top surface of the formed sheet to expand and form pore openings on the top surface (because once the wet substrate dries, the bubbles are no longer able to expand or form surface openings). Thus, the solid sheet formed by drying with such counter-gravity heating is characterized by an improved OCF structure that enables faster dissolution and other surprising and unexpected benefits.

In one embodiment, the anti-gravity heating direction is provided by a conduction-based heating/drying device, which is the same as or similar to that shown in fig. 5. For example, the aerated wet pre-mixture may be cast into a mold to form a sheet having two opposing sides. The mold may then be placed on a hot plate or heated moving belt or any other suitable heating device having a planar heating surface characterized by a controlled surface temperature of from about 80 ℃ to about 170 ℃, preferably from about 90 ℃ to about 150 ℃, more preferably from about 100 ℃ to about 140 ℃. Thermal energy is transferred by conduction from the planar heating surface to the bottom surface of the sheet of aerated wet premix so that the curing of the sheet begins at the bottom zone and gradually moves upward to finally reach the top zone. To ensure that the direction of heating is primarily counter-gravity (i.e. substantially away from the direction of gravity) in the process, it is preferred that the heating surface is the primary source of heat for the sheet during drying. If any other heating source is present, the overall heating direction may be changed accordingly. More preferably, the heated surface is the only source of heat for the sheet during drying.

In another embodiment, the countergravity heating direction is provided by a rotating drum based heating/drying apparatus, also referred to as drum drying or drum drying, similar to that shown in fig. 6. Drum drying is a type of contact drying process used to dry a liquid from a viscous premix of raw materials on the outer surface of a heated rotatable drum (also known as a drum or cylinder) at relatively low temperatures to form a sheet-like article. This is a continuous drying process, particularly suitable for bulk drying. Because drying is performed by contact heating/drying at relatively low temperatures, it is generally energy efficient and does not adversely affect the compositional integrity of the feedstock.

The heated rotatable cylinder for drum drying is internally heated, for example by steam or electricity, and rotated at a predetermined rotational speed by a motorized drive mounted on the pedestal stand. The heated rotatable cylinder or drum preferably has an outer diameter in the range of about 0.5 meters to about 10 meters, preferably about 1 meter to about 5 meters, more preferably about 1.5 meters to about 2 meters. It may have a controlled surface temperature of about 80 ℃ to about 170 ℃, preferably about 90 ℃ to about 150 ℃, more preferably about 100 ℃ to about 140 ℃. Further, such heated rotatable cylinders are rotated at a speed of about 0.005rpm to about 0.25rpm, preferably about 0.05rpm to about 0.2rpm, more preferably about 0.1rpm to about 0.18 rpm.

The heated rotatable cylinder is preferably coated on its outer surface with a non-stick coating. The non-stick coating may be coated on the outer surface of the heated rotatable cylinder, or it may be secured to the media of the outer surface of the heated rotatable cylinder. The media include, but are not limited to, heat resistant nonwoven fabrics, heat resistant carbon fibers, heat resistant metal or non-metal meshes, and the like. The non-stick coating is effective to maintain the structural integrity of the sheet-like article from damage during sheet forming.

A feed mechanism is also provided on the base support for adding an aerated wet pre-mix of the raw materials as described above onto the heated rotatable drum to form a thin layer of the viscous pre-mix onto the outer surface of the heated rotatable drum. Thus, this thin layer of premix is dried by contact heating/drying by a heated rotatable drum. The feed mechanism includes a feed chute mounted on the base frame and having at least one (preferably two) feed hoppers mounted thereon, an imaging device for dynamically viewing the feed, and an adjustment device for adjusting the position and tilt angle of the feed hoppers. By using the adjusting means to adjust the distance between the feed hopper and the outer surface of the heated rotatable drum, the need for different thicknesses of the formed sheet-like article can be met. The adjustment means may also be used to adjust the feed hopper to different angles of inclination to meet speed and quality material requirements. The feed tank may also include a spinning bar for agitating the wet pre-mixture therein prior to coating the wet pre-mixture onto the outer surface of the heated rotatable cylinder to avoid phase separation and settling. As mentioned above, such a spinning bar may also be used to aerate the wet premix as desired.

A heating cover can be further arranged on the base support to prevent rapid heat dissipation. The heating mantle also effectively saves the energy required for the heated rotatable drum, thereby achieving reduced energy consumption and cost savings. The heating mantle is a modular assembly structure or an integrated structure and can be freely detached from the base support. A suction device is also mounted on the heating hood for sucking the hot vapours to avoid any condensation water falling on the sheet product being formed.

An optional static scraping mechanism may also be mounted on the base support for scraping or scooping sheet-like articles that have been formed by the heated rotatable drum. A static scraping mechanism may be mounted on or to one side of the base support for transporting the already formed sheet product downstream for further processing. The static scraping mechanism can be moved automatically or manually closer to and further from the heated rotatable drum.

The flexible porous dissolvable solid structure article of the present invention is prepared as follows. First, a heated rotatable drum with a non-stick coating on the base support is driven by a motorized drive. Next, the adjusting device adjusts the feeding mechanism so that the distance between the feeding hopper and the outer surface of the heated rotatable drum reaches a preset value. At the same time, the feed hopper adds an aerated wet premix containing all or some of the raw materials used to make the flexible porous dissolvable solid structure article onto the outer surface of the heated rotatable drum to form thereon a thin layer of said aerated wet premix having the desired thickness as described in the previous section above. Optionally, the suction means of the heated hood sucks hot steam generated by the heated rotatable drum. Next, a static scraping mechanism scrapes/scoops the dried/cured sheet, which is formed from a thin layer of aerated wet premix after being dried by a heated rotatable drum at a relatively low temperature (e.g., 130 ℃). Without such a static scraping mechanism, the dried/cured sheet could also be peeled off manually or automatically and then rolled up by a roll.

The total drying time in the present invention depends on the formulation and solids content in the wet pre-mix, the drying temperature, the heat energy inflow and the thickness of the sheet to be dried. Preferably, the drying time is from about 1 minute to about 60 minutes, preferably from about 2 minutes to about 30 minutes, more preferably from about 2 minutes to about 15 minutes, still more preferably from about 2 minutes to about 10 minutes, most preferably from about 2 minutes to about 5 minutes.

During such drying time, the heating direction is arranged such that it lasts more than half of the drying time, preferably more than 55% or 60% of the drying time, substantially opposite to the direction of gravity (e.g. as in the rotary drum based heating/drying device described above), more preferably more than 75% or even 100% of the drying time (e.g. as in the bottom conduction based heating/drying device described above). Further, the sheet of aerated wet premix may be dried in a first heating direction for a first duration and then dried in a second, opposite heating direction for a second duration, while the first heating direction is substantially opposite to the direction of gravity, and the first duration is any value from 51% to 99% (e.g., from 55%, 60%, 65%, 70% to 80%, 85%, 90%, or 95%) of the total drying time. Such a change in heating direction can be readily achieved by various other arrangements not shown herein, for example, by an elongated heating band of serpentine shape that is rotatable along a longitudinal central axis.

Physical Properties of the solid sheet of the present invention

The flexible porous dissolvable solid sheet formed by the above processing steps is characterized by an improved pore structure that allows water to enter the sheet more easily and the sheet to dissolve in the water more quickly. Such improved pore structure is achieved primarily by adjusting the various processing conditions as described above, and they are relatively independent or less affected by the chemical formulation or the particular ingredients used to make such sheets.

Generally, such solid sheets may be characterized by: (i) a percent open cell content of about 80% to 100%, preferably about 85% to 100%, more preferably about 90% to 100%, as measured by test 3 below; and (ii) a total average pore diameter of from about 100 μm to about 2000 μm, preferably from about 150 μm to about 1000 μm, more preferably from about 200 μm to about 600 μm, as measured by the Micro-CT method described in test 2 below. The overall average pore size defines the porosity of the OCF structure of the present invention. The percent open content defines the interconnectivity between the pores in the OCF structure of the invention. The interconnectivity of OCF structures can also be described by star volume or Structure Model Index (SMI) as disclosed in WO2010077627 and WO 2012138820.

Such solid sheets of the invention have opposing top and bottom surfaces, while the top surface thereof may be characterized by a surface average pore size of greater than about 100 μm, preferably greater than about 110 μm, preferably greater than about 120 μm, more preferably greater than about 130 μm, most preferably greater than about 150 μm, as measured by the SEM method described in test 1 below. When compared to solid sheets formed by prior art heating/drying devices (e.g., convection-based, microwave-based, or impingement oven-based devices), the solid sheets formed by the inventive heating/drying devices of the present invention have significantly larger surface average pore sizes at their top surfaces (as shown in fig. 7A-7B and fig. 8A-8B, which are described in detail in example 1 below) because, under the directional heating of the particular arrangement of the present invention, the top surface of the formed aerated wet premix sheet is final dried/cured, and the gas bubbles near the top surface have the longest expansion time and form larger pore openings at the top surface.

Furthermore, the solid sheet formed by the heating/drying device of the present invention is characterized by a more uniform pore size distribution between different regions along its thickness direction, as compared to the sheet formed by the heating/drying device of the prior art. Specifically, the solid sheet of the present invention comprises a top region adjacent to the top surface, a bottom region adjacent to the bottom surface, and a middle region therebetween, and the top region, the middle region, and the bottom region all have the same thickness. Each of the top, middle, and bottom regions of such a solid sheet is characterized by an average pore size, and the ratio of the average pore size in the bottom region to the average pore size in the top region (i.e., the bottom-to-top average pore size ratio) is from about 0.6 to about 1.5, preferably from about 0.7 to about 1.4, preferably from about 0.8 to about 1.3, more preferably from about 1 to about 1.2. In contrast, solid sheets formed by prior art impingement oven-based heating/drying devices can have a bottom-to-top average pore diameter ratio of greater than 1.5, typically about 1.7 to 2.2 (as shown in example 1 below). Furthermore, the solid sheets of the present invention may be characterized by a bottom-to-middle average pore size ratio of from about 0.5 to about 1.5, preferably from about 0.6 to about 1.3, more preferably from about 0.8 to about 1.2, most preferably from about 0.9 to about 1.1, and a middle-to-top average pore size ratio of from about 1 to about 1.5, preferably from about 1 to about 1.4, more preferably from about 1 to about 1.2.

Furthermore, the relative standard deviation (RSTD) between the average pore diameters in the top, middle and bottom regions of the solid sheet of the present invention is no greater than 20%, preferably no greater than 15%, more preferably no greater than 10%, most preferably no greater than 5%. In contrast, solid sheets formed by prior art impingement oven-based heating/drying devices can have a relative standard deviation (RSTD) between top/middle/bottom average pore diameters of greater than 20%, possibly greater than 25% or even greater than 35% (as shown in example 1 below).

Preferably, the solid sheets of the present invention are further characterized by an average cell wall thickness of from about 5 μm to about 200 μm, preferably from about 10 μm to about 100 μm, more preferably from about 10 μm to about 80 μm, as measured by test 2 below.

The solid sheets of the present invention may contain small amounts of water. Preferably, it is characterized by a final moisture content of from 0.5% to 25%, preferably from 1% to 20%, more preferably from 3% to 10%, by weight of the solid sheet, as measured by test 4 below. The appropriate final moisture content in the resulting solid sheet ensures the desired flexibility/deformability of the sheet as well as providing a soft/smooth sensory feel to the consumer. If the final moisture content is too low, the sheet may be too brittle or too hard. If the final moisture content is too high, the sheet may be too tacky and its overall structural integrity may be compromised.

The solid sheets of the present invention may have a thickness ranging from about 0.6mm to about 3.5mm, preferably from about 0.7mm to about 3mm, more preferably from about 0.8mm to about 2mm, most preferably from about 1mm to about 1.5 mm. The thickness of the solid sheet can be measured using test 5 described below. The dried solid sheet may be slightly thicker than the aerated wet premix sheet due to pore expansion which in turn leads to an overall volume expansion.

The solid sheet of the present invention may also be characterized by about 50 grams/m as measured by test 6 described below²To about 250 g/m²Preferably about 80 g/m²To about 220 g/m²And more preferably about 100 grams/m²To about 200 g/m²Basis weight of (c).

Additionally, the solid sheets of the present invention may have a range of about 0.05 grams/cm as measured by test 7 below³To about 0.5 g/cm³Preferably about 0.06 g/cm³To about 0.4 g/cm³And more preferably about 0.07 g/cm³To about 0.2 g/cm³And most preferably about 0.08 g/cm³To about 0.15 g/cm³The density of (c). The density of the solid sheet of the present invention is lower than that of the sheet of aerated wet premix, also due to pore expansion which in turn leads to an overall volume expansion.

Further, the solid sheet of the present invention may be characterized by about 0.03m as measured by test 8 described below²G to about 0.25m²A/g, preferably about 0.04m²G to about 0.22m²G, more preferably 0.05m²G to 0.2m²G, most preferably 0.1m²G to 0.18m²Specific surface area in g. Of the solid sheet of the inventionThe specific surface area may represent its porosity and may affect its dissolution rate, e.g., the larger the specific surface area, the more porous the sheet and the faster its dissolution rate.

V. formulation of solid sheet of the invention

1.Water-soluble polymers

As noted above, the flexible porous dissolvable solid sheet of the present invention may be formed from a wet premix comprising a water soluble polymer. Such water-soluble polymers can function as carriers for film formers, structurants, and other active ingredients (e.g., surfactants, emulsifiers, builders, chelating agents, perfumes, colorants, etc.) in the resulting solid sheet.

Preferably, the wet premix may comprise from about 3% to about 20% by weight of the premix of a water soluble polymer, in one embodiment from about 5% to about 15% by weight of the premix of a water soluble polymer, and in one embodiment from about 7% to about 10% by weight of the premix of a water soluble polymer.

After drying, it is preferred that the water-soluble polymer be present in the flexible porous dissolvable solid sheet of the present invention in an amount ranging from about 10% to about 40%, preferably from about 15% to about 30%, more preferably from about 20% to about 25%, by total weight of the solid sheet. In a particularly preferred embodiment of the invention, the total amount of water-soluble polymer(s) present in the flexible porous dissolvable solid sheet of the invention does not exceed 25% of the total weight of such an article.

Water-soluble polymers suitable for use in the practice of the present invention may be selected from those having a weight average molecular weight in the following ranges: from about 50,000 daltons to about 400,000 daltons, preferably from about 60,000 daltons to about 300,000 daltons, more preferably from about 70,000 daltons to about 200,000 daltons, most preferably from about 80,000 daltons to about 150,000 daltons. The weight average molecular weight is calculated by calculating the product of the average molecular weight of each of the polymeric starting materials and their respective relative weight percentages by weight of the total weight of the polymers present in the porous solid. The weight average molecular weight of the water-soluble polymer used herein may affect the viscosity of the wet premix, which may in turn affect the number and size of the gas bubbles during the aeration step and the pore expansion/opening results during the drying step. In addition, the weight average molecular weight of the water-soluble polymer may affect the overall film-forming properties of the wet premix and its compatibility/incompatibility with certain surfactants.

The water-soluble polymers of the present invention may include, but are not limited to, synthetic polymers including polyvinyl alcohol, polyvinylpyrrolidone, polyalkylene oxide, polyacrylate, caprolactam, polymethacrylate, polymethylmethacrylate, polyacrylamide, polymethacrylamide, polydimethylacrylamide, polyethylene glycol monomethacrylate, copolymers of acrylic acid and methyl acrylate, polyurethane, polycarboxylic acid, polyvinyl acetate, polyester, polyamide, polyamine, polyethyleneimine, maleic acid/(acrylate or methacrylate) copolymer, copolymer of methyl vinyl ether and maleic anhydride, copolymer of vinyl acetate and crotonic acid, copolymer of vinylpyrrolidone and vinyl acetate, copolymer of vinylpyrrolidone and caprolactam, vinylpyrrolidone/vinyl acetate copolymer, anionic monomer, poly (alkylene oxide), copolymers of cationic and amphoteric monomers, and combinations thereof.

The water-soluble polymer of the present invention may also be selected from polymers derived from natural sources, including those of vegetable origin, examples of which include karaya gum, tragacanth gum, acacia gum, acetomorphan, konjac glucomannan, acacia gum, gum dapa, whey protein isolate, and soy protein isolate; seed extracts including guar gum, locust bean gum, quince seed and plantago seed; seaweed extracts such as carrageenan, alginate and agar; fruit extracts (pectin); those of microbial origin, including xanthan gum, gellan gum, pullulan, hyaluronic acid, chondroitin sulfate and dextran; and those of animal origin, including casein, gelatin, keratin hydrolysates, sulfokeratin, albumin, collagen, gluten, glucagon, gluten, zein, and shellac.

Modified natural polymers may also be used as the water-soluble polymer in the present invention. Suitable modified natural polymers include, but are not limited to, cellulose derivatives such as hydroxypropyl methylcellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, ethyl cellulose, carboxymethyl cellulose, cellulose acetate phthalate, nitrocellulose, and other cellulose ethers/esters; and guar derivatives such as hydroxypropyl guar.

The water-soluble polymer of the present invention may include starch. As used herein, the term "starch" includes both naturally occurring or modified starches. Typical natural sources of starch may include grains, tubers, roots, legumes, and fruits. More specific natural sources may include corn, pea, potato, banana, barley, wheat, rice, sago, amaranth, tapioca, arrowroot, canna, sorghum, and waxy or high amylase varieties thereof. Native starch may be modified by any modification method known in the art to form modified starch, including physically modified starch, such as sheared starch or heat inhibited starch; chemically modified starches such as those that have been crosslinked, acetylated and organically esterified, hydroxyethylated and hydroxypropylated, phosphorylated, and inorganically esterified, their cationic, anionic, nonionic, amphoteric, and zwitterionic derivatives, and their succinate and substituted succinate derivatives; conversion products derived from any starch, including fluid or thin paste starches prepared by oxidation, enzymatic conversion, acid hydrolysis, heating or acid dextrinization, heat treated and/or sheared products may also be used herein; and pregelatinized starches known in the art.

Preferred water-soluble polymers of the present invention include polyvinyl alcohol, polyvinyl pyrrolidone, polyalkylene oxides, starch and starch derivatives, pullulan, gelatin, hydroxypropyl methylcellulose, and carboxymethyl cellulose. More preferred water-soluble polymers of the present invention include polyvinyl alcohol and hydroxypropylmethyl cellulose.

The most preferred water-soluble polymer of the present invention is polyvinyl alcohol characterized by a degree of hydrolysis in the range of about 40% to about 100%, preferably about 50% to about 95%, more preferably about 70% to about 92%, most preferably about 80% to about 90%. Commercially available polyethyleneEnols include those available under the trade name CELVOL, including but not limited to CELVOL 523, CELVOL 530, CELVOL540, CELVOL518, CELVOL 513, CELVOL 508, CELVOL 504 from Celanese Corporation (Texas, USA); to be provided with

And POVAL^TMThose available under the trade name Kuraray Europe GmbH (Frankfurt, Germany); and PVA1788 (also known as PVA BP17), commercially available from various suppliers including Lubon vinyl Co. (Nanjing, China); and combinations thereof. In a particularly preferred embodiment of the invention, the flexible porous dissolvable solid sheet comprises from about 10% to about 25%, more preferably from about 15% to about 23%, polyvinyl alcohol, having a weight average molecular weight ranging from 80,000 daltons to about 150,000 daltons and a degree of hydrolysis ranging from about 80% to about 90%, by total weight of such articles.

In addition to the polyvinyl alcohol described above, a single starch or a combination of starches may be used as a filler in an amount that can reduce the total content of water-soluble polymer needed, so long as it helps provide a solid sheet having the necessary structural and physical/chemical properties as described herein. However, too much starch may contain the solubility and structural integrity of the sheet. Thus, in a preferred embodiment of the invention, it is desirable that the solid sheet comprises no more than 20%, preferably from 0% to 10%, more preferably from 0% to 5%, most preferably from 0% to 1% starch by weight of the solid sheet.

2.Surface active agent

In addition to the water-soluble polymers described above, the solid sheet articles of the present invention also comprise one or more surfactants. The surfactant may act as an emulsifier during the aeration process to generate a sufficient amount of stable gas bubbles to form the desired OCF structure of the present invention. In addition, surfactants can function as active ingredients to deliver desired cleaning benefits.

In a preferred embodiment of the invention, the solid sheet comprises one or more surfactants selected from the group consisting of: anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants, amphoteric surfactants, polymeric surfactants, or combinations thereof. Depending on the desired application of such solid sheets and the desired consumer benefit to be achieved, different surfactants may be selected. One benefit of the present invention is that the OCF structure of the solid sheet allows for the incorporation of high surfactant levels while still providing rapid dissolution. Thus, highly concentrated cleaning compositions can be formulated into the solid sheets of the present invention to provide a new and superior cleaning experience to the consumer.

Surfactants as used herein may include both surfactants from the conventional sense (i.e., those that provide consumer noticeable lather) and emulsifiers (i.e., those that do not provide any lather performance but are primarily used as processing aids for producing stable foam structures). Examples of emulsifiers for use as the surfactant component herein include mono-and diglycerides, fatty alcohols, polyglycerol esters, propylene glycol esters, sorbitan esters, and other emulsifiers known or otherwise commonly used to stabilize air interfaces.

The total amount of surfactant present in the solid sheet articles of the present invention can range broadly from about 5% to about 80%, preferably from about 10% to about 70%, more preferably from about 30% to about 65%, by total weight of the solid sheet article. Accordingly, the wet premix may comprise from about 1% to about 40% by weight of the wet premix of a surfactant, in one embodiment from about 2% to about 35% by weight of the wet premix of a surfactant, in one embodiment from about 5% to about 30% by weight of the wet premix of a surfactant.

In a preferred embodiment of the present invention, the solid sheet article of the present invention is a cleaning product comprising from about 30% to about 80%, preferably from about 40% to about 70%, more preferably from about 50% to about 65%, by total weight of the solid sheet article, of one or more surfactants. In this case, the wet premix may comprise from about 10% to about 40% by weight of the wet premix of surfactant, in one embodiment from about 12% to about 35% by weight of the wet premix of surfactant, and in one embodiment from about 15% to about 30% by weight of the wet premix of surfactant.

Non-limiting examples of anionic surfactants suitable for use herein include alkyl sulfates and alkyl ether sulfates, sulfated monoglycerides, sulfonated olefins, alkylaryl sulfonates, primary or secondary alkane sulfonates, alkyl sulfosuccinates, acyl taurates, acyl isethionates, alkyl glyceryl ether sulfonates, sulfonated methyl esters, sulfonated fatty acids, alkyl phosphates, acyl glutamates, acyl sarcosinates, alkyl sulfoacetates, acylated peptides, alkyl ether carboxylates, acyl lactylates, anionic fluorosurfactants, sodium lauroyl glutamate, and combinations thereof.

One class of anionic surfactants particularly suitable for use in the practice of the present invention includes C₆-C₂₀Linear Alkylbenzene Sulphonate (LAS) surfactant. LAS surfactants are well known in the art and are readily available by sulphonation of commercially available linear alkylbenzenes. Exemplary C that can be used in the present invention₁₀-C₂₀Linear alkyl benzene sulfonates including C₁₀-C₂₀Alkali metal, alkaline earth metal or ammonium salt of linear alkyl benzene sulphonic acid and is preferably C₁₁-C₁₈Or C₁₁-C₁₄Sodium, potassium, magnesium and/or ammonium linear alkyl benzene sulphonic acid salts. More preferably C₁₂And/or C₁₄Sodium or potassium salt of linear alkyl benzene sulphonic acid and most preferably C₁₂And/or C₁₄Sodium salt of linear alkyl benzene sulphonic acid i.e. sodium dodecylbenzene sulphonate or sodium tetradecylbenzene sulphonate.

LAS provides excellent cleaning benefits and is particularly suitable for laundry detergent applications. It is a surprising and unexpected discovery of the present invention that when a polyvinyl alcohol having a relatively high weight average molecular weight (e.g., from about 50,000 daltons to about 400,000 daltons, preferably from about 60,000 daltons to about 300,000 daltons, more preferably from about 70,000 daltons to about 200,000 daltons, and most preferably from about 80,000 daltons to about 150,000 daltons) is used as a film former and carrier, LAS can be used as the primary surfactant, i.e., present in an amount greater than 50% by weight of the total surfactant content in the solid sheet, without adversely affecting the film forming properties and stability of the overall composition. Accordingly, in one particular embodiment of the invention, LAS is used as the primary surfactant in the solid sheet. If present, the amount of LAS in the solid sheets of the present invention may range from about 10% to about 70%, preferably from about 20% to about 65%, more preferably from about 40% to about 60%, by total weight of the solid sheet.

Another class of anionic surfactants suitable for use in the practice of the present invention include Sodium Trideceth Sulfate (STS) which has a weight average degree of alkoxylation in the range of from about 0.5 to about 5, preferably from about 0.8 to about 4, more preferably from about 1 to about 3, and most preferably from about 1.5 to about 2.5. Trideceth is a 13 carbon branched alkoxylated hydrocarbon, which in one embodiment contains an average of at least 1 methyl branch per molecule. STS used in the present invention may include st (eoxpoy) S, and EOx means a repeating ethylene oxide unit, the number of repetition x of which is in the range of 0 to 5, preferably 1 to 4, more preferably 1 to 3, and POy means a repeating propylene oxide unit, the number of repetition y of which is in the range of 0 to 5, preferably 0 to 4, more preferably 0 to 2. It is understood that materials such as ST2S having a weight average degree of ethoxylation of about 2, for example, may contain significant amounts of molecules without ethoxylates, 1 mole ethoxylates, 3 moles ethoxylates, etc., while the distribution of ethoxylation may be broad, narrow, or trapped, which still results in a total weight average degree of ethoxylation of about 2. STS is particularly useful in personal cleansing applications, and it is a surprising and unexpected discovery of the present invention that when polyvinyl alcohol having a relatively high weight average molecular weight (e.g., from about 50,000 daltons to about 400,000 daltons, preferably from about 60,000 daltons to about 300,000 daltons, more preferably from about 70,000 daltons to about 200,000 daltons, and most preferably from about 80,000 daltons to about 150,000 daltons) is used as a film former and carrier, STS can be used as the primary surfactant, i.e., present in an amount greater than 50% by weight of the total surfactant content in the solid sheet, without adversely affecting the film forming properties and stability of the overall composition. Accordingly, in one embodiment of the present invention, STS is used as the primary surfactant in the solid sheet. If present, the amount of STS in the solid sheets of the present invention can range from about 10% to about 70%, preferably from about 20% to about 65%, more preferably from about 40% to about 60%, by total weight of the solid sheet.

Another class of anionic surfactants suitable for use in the practice of the present invention include alkyl sulfates. These materials have the corresponding formula ROSO₃M, wherein R is an alkyl or alkenyl group having from about 6 to about 20 carbon atoms, x is from 1 to 10, and M is a water soluble cation such as ammonium, sodium, potassium, and triethanolamine. Preferably, R has from about 6 to about 18, preferably from about 8 to about 16, more preferably from about 10 to about 14 carbon atoms. Previously, un-alkoxylated C₆-C₂₀Straight or branched Alkyl Sulfate (AS) is considered to be a preferred surfactant in which to dissolve the solid sheet, particularly AS the primary surfactant therein, because it has compatibility with low molecular weight polyvinyl alcohols (e.g., those having a weight average molecular weight of no greater than 50,000 daltons) in terms of film forming properties and storage stability. However, it is a surprising and unexpected discovery of the present invention that when polyvinyl alcohol having a relatively high weight average molecular weight (e.g., from about 50,000 daltons to about 400,000 daltons, preferably from about 60,000 daltons to about 300,000 daltons, more preferably from about 70,000 daltons to about 200,000 daltons, and most preferably from about 80,000 daltons to about 150,000 daltons) is used as a film former and carrier, other surfactants such as LAS and/or STS can be used as the primary surfactant in the solid sheet without adversely affecting the film forming properties and stability of the overall composition. Thus, in a particularly preferred embodiment of the present invention, it is desirable to provide a solid sheet having no more than about 20%, preferably from 0% to about 10%, more preferably from 0% to about 5%, most preferably from 0% to about 1%, by weight of the solid sheet, of AS.

Another class of anionic surfactants suitable for use in the practice of the present invention comprises C₆-C₂₀Linear or branched Alkyl Alkoxy Sulfates (AAS). Within this class, it is particularly preferred to have correspondingFormula RO (C)₂H₄O)_xSO₃M is a linear or branched Alkyl Ethoxy Sulfate (AES) where R is an alkyl or alkenyl group of from about 6 to about 20 carbon atoms, x is from 1 to 10, and M is a water soluble cation such as ammonium, sodium, potassium, and triethanolamine. Preferably, R has from about 6 to about 18, preferably from about 8 to about 16, more preferably from about 10 to about 14 carbon atoms. AES surfactants are typically prepared as the condensation product of ethylene oxide with a monohydric alcohol having from about 6 to about 20 carbon atoms. Useful alcohols can be derived from fats, such as coconut oil or tallow, or can be synthetic. Lauryl alcohol and straight chain alcohols derived from coconut oil are preferred herein. Such alcohols are reacted with from about 1 to about 10, preferably from about 3 to about 5, especially about 3, mole fractions of ethylene oxide, and the resulting mixture of molecular species (e.g., having an average of 3 moles of ethylene oxide per mole of alcohol) is sulfated and neutralized. Highly preferred AES are those comprising a mixture of individual compounds having an average alkyl chain length of from about 10 to about 16 carbon atoms and an average degree of ethoxylation of from about 1 to about 4 moles of ethylene oxide. If present, the amount of AAS in the solid sheets of the present invention can range from about 2% to about 40%, preferably from about 5% to about 30%, more preferably from about 8% to about 12%, by total weight of the solid sheet.

Other suitable anionic surfactants include those of the formula [ R ]¹-SO₃-M]Water soluble salts of organic sulfuric acid reaction products of (2), wherein R¹Selected from straight or branched chain saturated aliphatic hydrocarbon groups having from about 6 to about 20, preferably from about 10 to about 18, carbon atoms; and M is a cation. Preference is given to sulfonation of C_10-18The α -olefins from which the olefin sulfonates are derived are mono-olefins having from about 12 to about 24 carbon atoms, preferably from about 14 to about 16 carbon atoms.

Another class of anionic surfactants suitable for use in fabric and home care compositions are the beta-alkoxy alkane sulfonates. These compounds have the following structure:

wherein R is₁Is a straight chain alkyl group having from about 6 to about 20 carbon atoms, R₂Is a lower alkyl group having from about 1 (preferably) to about 3 carbon atoms, and M is a water-soluble cation as described above.

Other examples of suitable anionic surfactants are the reaction products of fatty acids esterified with isethionic acid and neutralized with sodium hydroxide, wherein the fatty acids are derived from, for example, coconut oil; sodium or potassium salts of fatty acid amides of methyl tauride, wherein the fatty acids are derived from, for example, coconut oil. Still other suitable anionic surfactants are succinamates, examples of which include disodium N-octadecyl sulfosuccinamate; diammonium lauryl sulfosuccinamate; tetrasodium N- (1, 2-dicarboxyethyl) -N-octadecyl sulfosuccinamate; diamyl esters of sodium sulfosuccinate, dihexyl esters of sodium sulfosuccinate, and dioctyl esters of sodium sulfosuccinate.

The nonionic surfactant that may be included in the solid sheets of the present invention may be any conventional nonionic surfactant, including but not limited to: alkyl alkoxylated alcohols, alkyl alkoxylated phenols, alkyl polysaccharides (especially alkyl glucosides and alkyl polyglucosides), polyhydroxy fatty acid amides, alkoxylated fatty acid esters, sucrose esters, sorbitan esters and alkoxylated derivatives of sorbitan esters, amine oxides, and the like. Preferred nonionic surfactants are those having the formula R¹(OC₂H₄)_nThose of OH, wherein R¹Is C₈-C₁₈An alkyl group or an alkylphenyl group, and n is from about 1 to about 80. Particularly preferred are C's having a weight average degree of ethoxylation of from about 1 to about 20, preferably from about 5 to about 15, more preferably from about 7 to about 10₈-C₁₈Alkylethoxylated alcohols, e.g. commercially available from Shell

A nonionic surfactant. Can be used in this contextOther non-limiting examples of non-ionic surfactants of (a) include: c₆-C₁₂An alkylphenol alkoxylate wherein the alkoxylate units may be ethyleneoxy units, propyleneoxy units, or mixtures thereof; c₁₂-C₁₈Alcohol and C₆-C₁₂Condensates of alkylphenols with ethylene oxide/propylene oxide block polymers, e.g. from BASF

C₁₄-C₂₂Mid-chain branched alcohols, BA; c₁₄-C₂₂Mid-chain branched alkyl alkoxylates, BAE_xWherein x is 1 to 30; alkyl polysaccharides, in particular alkyl polyglycosides; polyhydroxy fatty acid amides; and ether-terminated poly (alkoxylated) alcohol surfactants. Suitable nonionic surfactants also include BASF under the trade name BASFThose that are sold.

In a preferred embodiment, the nonionic surfactant is selected from sorbitan esters and alkoxylated derivatives of sorbitan esters, including sorbitan monolaurate, (both available from Uniqema)

20) Sorbitan monopalmitate ester(s) ((s))

40) Sorbitan monostearate (C)

60) Sorbitan tristearate (C) ((C))65) Sorbitan monooleate (C)

80) Trioleic acid dehydrated mountainPyritol ester (B)

85) Sorbitan isostearate, polyoxyethylene monolaurate (20) sorbitan ester(s) ((s))20) Polyoxyethylene (20) sorbitan monopalmitate (C) ((C))

40) Polyoxyethylene (20) sorbitan monostearate (C)60) Polyoxyethylene (20) sorbitan monooleate (C:)

80) Polyoxyethylene (4) sorbitan monolaurate (4) ((R))21) Polyoxyethylene monostearate (4) sorbitan ester (C)

61) Polyoxyethylene monooleate (5) sorbitan ester (C)81) And combinations thereof.

The most preferred nonionic surfactants for use in the practice of the present invention include C₆-C₂₀A linear or branched alkyl Alkoxylated Alcohol (AA) having a weight average degree of alkoxylation ranging from 5 to 15, more preferably C₁₂-C₁₄A linear ethoxylated alcohol having a weight average degree of alkoxylation ranging from 7 to 9. If present, the amount of the AA-type nonionic surfactant in the solid sheets of the present invention can range from about 2% to about 40%, preferably from about 5% to about 30%, more preferably from about 8% to about 12%, by total weight of the solid sheetWithin the range of (1).

Amphoteric surfactants suitable for use in the solid sheets of the present invention include those that are broadly described as derivatives of aliphatic secondary and tertiary amines in which the aliphatic radical can be straight or branched chain and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic water solubilizing group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. Examples of compounds falling within the scope of this definition are sodium 3-dodecylaminopropionate, sodium 3-dodecylaminopropane sulfonate, sodium lauryl sarcosinate, N-alkyltaurines (such as that made by the reaction of dodecylamine with sodium isethionate) and N-higher alkyl aspartic acids.

One class of amphoteric surfactants particularly suited for incorporation into solid sheets for personal care applications (e.g., shampoos, facial or body cleansers, etc.) includes alkyl amphoacetates, such as lauroamphoacetate and cocoamphoacetate. The alkylamphoacetates may include monoacetate and diacetate. In certain types of alkylamphoacetates, the diacetate salt is an impurity or an unintended reaction product. If present, the amount of alkylamphoacetate in the solid sheets of the present invention may range from about 2% to about 40%, preferably from about 5% to about 30%, more preferably from about 10% to about 20%, by total weight of the solid sheet.

Suitable zwitterionic surfactants include those that are broadly described as derivatives of aliphatic quaternary ammonium, phosphonium, and sulfonium compounds, in which the aliphatic radicals can be straight or branched chain, and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. Such suitable zwitterionic surfactants can be represented by the following formula:

wherein R is²Containing from about 8 to about 18 carbon atoms, from 0 to about 10An ethylene oxide moiety, and an alkyl, alkenyl or hydroxyalkyl group of from 0 to about 1 glyceryl moiety; y is selected from the group consisting of: nitrogen, phosphorus and sulfur atoms; r³Is an alkyl or monohydroxyalkyl group containing from about 1 to about 3 carbon atoms; x is 1 when Y is a sulfur atom, and X is 2 when Y is a nitrogen or phosphorus atom; r⁴Is an alkylene or hydroxyalkylene group having from about 1 to about 4 carbon atoms, and Z is a group selected from the group consisting of: carboxylate, sulfonate, sulfate, phosphonate, and phosphate groups.

Other zwitterionic surfactants suitable for use herein include betaines, including higher alkyl betaines such as coco dimethyl carboxymethyl betaine, coco amidopropyl betaine, coco betaine, lauryl amidopropyl betaine, oleyl betaine, lauryl dimethyl carboxymethyl betaine, lauryl dimethyl α -carboxyethyl betaine, cetyl dimethyl carboxymethyl betaine, lauryl bis- (2-hydroxyethyl) carboxymethyl betaine, stearyl bis- (2-hydroxypropyl) carboxymethyl betaine, oleyl dimethyl gamma-carboxypropyl betaine, and lauryl bis- (2-hydroxypropyl) α -carboxyethyl betaine, sulfobetaines may be represented by coco dimethyl sulfopropyl betaine, stearyl dimethyl sulfopropyl betaine, lauryl dimethyl sulfoethyl betaine, lauryl bis- (2-hydroxyethyl) sulfopropyl betaine, and the like, amido betaines and amidosulfobetaines, wherein RCONH (CH) is₂)₃Group (wherein R is C)₁₁-C₁₇Alkyl) is attached to the betaine nitrogen atom and may also be used in the present invention.

Cationic surfactants are also useful herein, particularly in fabric softeners and hair conditioner products. When used to prepare products containing a cationic surfactant as the primary surfactant, it is preferred that such cationic surfactant be present in an amount ranging from about 2% to about 30%, preferably from about 3% to about 20%, more preferably from about 5% to about 15%, by total weight of the solid sheet.

Cationic surfactants can include DEQA compounds, which include descriptions of diamido actives as well as actives having mixed amido and ester linkages. Preferred DEQA compounds are generally prepared by the reaction of alkanolamines such as MDEA (methyldiethanolamine) and TEA (triethanolamine) with fatty acids. Some of the materials typically produced by such reactions include N, N-bis (acyloxyethyl) -N, N-dimethylammonium chloride, or N, N-bis (acyloxyethyl) -N, N-methylhydroxyethylmethylammonium methosulfate, wherein the acyl groups are derived from tallow, unsaturated and polyunsaturated fatty acids.

Other actives suitable for use as cationic surfactants include the reaction product of a fatty acid and a dialkylenetriamine in a molecular ratio of, for example, about 2:1, the reaction product comprising a compound of the formula:

R¹—C(O)-NH-R²-NH-R³-NH-C(O)-R¹

wherein R is¹、R²As defined above, and each R³Is C_1-6Alkylene, preferably ethylene. Examples of such actives are tallowic acid, canola oleic acid or reaction products of oleic acid and diethylenetriamine in a molecular ratio of about 2:1, the reaction product mixture comprising N, N "-ditallowdiethylenetetramine, N" -dilerucic oleoyldiethylenetriamine or N, N "-dioleoyldiethylenetriamine, respectively, having the formula:

R¹-C(O)-NH-CH₂CH₂-NH-CH₂CH₂-NH-C(O)-R¹

wherein R is²And R³Is a divalent ethylene radical, R¹As defined above, and when R¹Acceptable examples of such structures include those available from Henkel Corporation when oleoyl of commercially available oleic acid derived from plant or animal sources223LL or7021。

Another active useful as a cationic surfactant has the formula:

[R¹-C(O)-NR-R²-N(R)₂—R³—NR—C(O)—R¹]⁺X^-

r, R therein¹、R²、R³And X^-As defined above; examples of such actives are di-fatty amidoamine based softeners having the following formula:

[R¹-C(O)-NH-CH₂CH₂-N(CH₃)(CH₂CH₂OH)-CH₂CH₂-NH-C(O)-R¹]⁺CH₃SO₄ ^-wherein R is¹C (O) is respectively under the trade name222LT、222. And110 oleoyl, soft tallow, or hardened tallow commercially available from Degussa.

A second class of DEQA ("DEQA (2)") compounds suitable as active materials for use as cationic surfactants have the general formula:

[R₃N⁺CH₂CH(YR¹)(CH₂YR¹)]X^-

each of which Y, R, R¹And X^-Have the same meaning as above. An example of a preferred DEQA (2) is the "propyl" ester quaternary ammonium fabric softener active having the formula 1, 2-bis (acyloxy) -3-trimethylpropylammonium chloride.

Polymeric surfactants suitable for use in the personal care compositions of the present invention include, but are not limited to, block copolymers of ethylene oxide and fatty alkyl residues, block copolymers of ethylene oxide and propylene oxide, hydrophobically modified polyacrylates, hydrophobically modified celluloses, silicone polyethers, silicone copolyol esters, polydimethylsiloxane bis-quaternary ammonium salts, and co-modified amino/polyether siloxanes.

3.Plasticizer

In a preferred embodiment of the present invention, the flexible porous dissolvable solid sheet of the present invention further comprises a plasticizer, preferably in an amount in the range of from about 0.1% to about 25%, preferably from about 0.5% to about 20%, more preferably from about 1% to about 15%, most preferably from 2% to 12% by total weight of the solid sheet. Accordingly, the wet pre-mix used to form such solid sheets may comprise from about 0.02% to about 20% by weight of the wet pre-mix, in one embodiment from about 0.1% to about 10% by weight of the wet pre-mix, in one embodiment from about 0.5% to about 5% by weight of the wet pre-mix.

Plasticizers suitable for use in the present invention include, for example, polyols, copolyols, polycarboxylic acids, polyesters, dimethicone copolyols, and the like.

Examples of useful polyols include, but are not limited to: glycerol, diglycerol, ethylene glycol, polyethylene glycol (especially 200-.

Examples of polycarboxylic acids include, but are not limited to, citric acid, maleic acid, succinic acid, polyacrylic acid, and polymaleic acid.

Examples of suitable polyesters include, but are not limited to, triacetin, acetylated monoglycerides, diethyl phthalate, triethyl citrate, tributyl citrate, acetyltriethyl citrate, acetyltributyl citrate.

Examples of suitable dimethicone copolyols include, but are not limited to, PEG-12 dimethicone, PEG/PPG-18/18 dimethicone, and PPG-12 dimethicone.

Other suitable plasticizers include, but are not limited to, alkyl and allyl phthalates, naphthyl esters, lactates (e.g., sodium, ammonium and potassium salts), sorbitan polyoxyethylene ether-30, urea, lactic acid, sodium Pyrrolidone Carboxylate (PCA), sodium hyaluronate or hyaluronic acid, soluble collagen, modified proteins, monosodium L-glutamate, α and β -hydroxy acids such as glycolic, lactic, citric, maleic and salicylic acids, glyceryl polymethacrylates, polymeric plasticizers such as polyquaterniums, proteins and amino acids such as glutamic, aspartic and lysine, hydrogen starch hydrolysates, other low molecular weight esters (e.g., C₂-C₁₀Esters of alcohols and acids); and any other water-soluble plasticizers known to those skilled in the art of the food and plastic industries; and mixtures thereof.

Particularly preferred examples of plasticizers include glycerin, ethylene glycol, polyethylene glycol, propylene glycol, and mixtures thereof. The most preferred plasticizer is glycerol.

4.Additional ingredients

In addition to the above ingredients, such as water-soluble polymers, surfactants, and plasticizers, the solid sheets of the present invention may also contain one or more additional ingredients, depending on their intended use. Such one or more additional ingredients may be selected from fabric care actives, dishwashing actives, hard surface cleaning actives, cosmetic and/or skin care actives, personal cleaning actives, hair care actives, oral care actives, feminine care actives, infant care actives, and any combination thereof.

Suitable fabric care actives include, but are not limited to: organic solvent (straight or branched lower C)₁-C₈Alcohols, glycols, glycerol or glycols; lower amine solvents, e.g. C₁-C₄Alkanolamines, and mixtures thereof; more specifically, 1, 2-propanediol, ethanol, glycerol, monoethanolamine, and triethanolamine), a carrier, a hydrotrope, a builder, a chelating agent, a dispersantEnzymes and enzyme stabilizers, catalytic materials, bleaching agents (including photobleaches) and bleach activators, perfumes (including encapsulated perfumes or perfume microcapsules), colorants (such as pigments and dyes, including shading dyes), brighteners, dye transfer inhibitors, clay soil removal/anti-redeposition agents, structurants, rheology modifiers, suds suppressors, processing aids, fabric softeners, antimicrobials, and the like.

Suitable hair care actives include, but are not limited to: class II moisture control materials (salicylic acids and derivatives, organic alcohols and esters) for curl reduction, cationic surfactants (especially water insoluble types with a solubility in water at 25 ℃ preferably below 0.5g/100g water, more preferably below 0.3g/100g water), high melting point fatty compounds (e.g., fatty alcohols, fatty acids, and mixtures thereof with a melting point of 25 ℃ or higher, preferably 40 ℃ or higher, more preferably 45 ℃ or higher, still more preferably 50 ℃ or higher), silicone compounds, conditioning agents (e.g., hydrolyzed collagen from Hormel under the trade name Peptein 2000, vitamin E from Eisai under the trade name Emix-d, panthenol from Roche, panthenyl ethyl ether from Roche, hydrolyzed keratin, proteins, plant extracts, and nutrients), preservatives (e.g., benzyl alcohol, methyl alcohol, ethyl ether, hydrolyzed keratin, proteins, vegetable extracts, and nutrients), and the like, Methylparaben, propylparaben, and imidazolidinyl urea), pH adjusting agents (such as citric acid, sodium citrate, succinic acid, phosphoric acid, sodium hydroxide, sodium carbonate), salts (such as potassium acetate and sodium chloride), colorants, fragrances or fragrances, sequestering agents (such as disodium edetate), ultraviolet and infrared screening and absorbing agents (such as octyl salicylate), hair bleaches, hair perming agents, hair fixatives, anti-dandruff agents, antimicrobial agents, hair growth or restoration agents, co-solvents, or other additional solvents, and the like.

Suitable Cosmetic and/or skin care actives include those materials which are approved for use in cosmetics and described in references such as "CTFA Cosmetic Ingredient Handbook" second edition (The Cosmetic, Toiletries, and france Association, inc.1988, 1992). Other non-limiting examples of suitable cosmetic and/or skin care actives include preservatives, fragrances or fragrances, colorants or dyes, thickeners, moisturizers, emollients, pharmaceutical actives, vitamins or nutrients, sunscreens, deodorants, sensates, botanical extracts, nutrients, astringents, cosmetic particles, absorbent particles, fibers, anti-inflammatory agents, skin lightening agents, skin tone agents (which may be used to improve overall skin tone and may include vitamin B3 compounds, sugar amines, hexamidine compounds, salicylic acid, 1, 3-dihydroxy-4-alkylbenzenes such as hexylresorcinol and retinoids), skin tanning agents, exfoliants, humectants, enzymes, antioxidants, free radical scavengers, anti-wrinkle actives, anti-acne agents, acids, bases, minerals, suspending agents, pH adjusters, pigment particles, skin tanning agents, exfoliants, skin lightening agents, enzymes, skin lightening agents, anti-wrinkle actives, anti-acne agents, antimicrobial agents, insect repellents, shaving lotions, co-solvents or other additional solvents, and the like.

The solid sheets of the present invention may also comprise other optional ingredients known to be used or useable in compositions, provided that such optional materials are compatible with the selected essential materials described herein, or do not otherwise unduly impair product performance.

Non-limiting examples of product type embodiments that may be formed from the solid sheets of the present invention include laundry detergent products, fabric softening products, hand cleansing products, shampoos or other hair treatment products, body cleansing products, shave preparation products, dish cleansing products, personal care substrates containing pharmaceuticals or other skin care actives, moisturizing products, sunscreen products, beauty or skin care products, deodorizing products, oral care products, feminine cleansing products, baby care products, fragrance containing products, and the like.

Assembling a plurality of sheets into a multilayer dissolvable solid article

Once the flexible dissolvable porous solid sheet material as described above is formed, two or more such sheets may be further assembled together to form the multilayer dissolvable solid article of the present invention having a desired aspect ratio (i.e., D/z ratio), as described above.

The multilayer dissolvable solid articles of the present invention can have any desired three-dimensional shape including, but not limited to: spherical, cubic, rectangular, polygonal, elliptical, cylindrical, rod-shaped, sheet-shaped, flower-shaped, fan-shaped, star-shaped, disc-shaped, and the like. The sheets may be combined/treated by any method known in the art, examples of which include, but are not limited to, chemical methods, mechanical methods, and combinations thereof. Such combination and/or processing steps are collectively referred to herein as a "conversion" process, i.e., it is used to convert the two or more flexible, dissolvable porous sheets of the present invention into a dissolvable solid article having a desired three-dimensional shape.

As noted above, the surprising and unexpected discovery of the present invention is that a multi-layer dissolvable solid article of the present invention formed by stacking together multiple layers of the above-described flexible, dissolvable porous sheets is more soluble than a single layer dissolvable solid article having the same aspect ratio. This allows such solid articles to extend significantly in the thickness or z-direction to create a three-dimensional product shape that is easier to handle and more aesthetically pleasing to the consumer (e.g., products in the form of thick pads or even cubes).

In particular, the multilayer dissolvable solid articles of the present invention are characterized by an aspect ratio in the range of from 1 to about 10, preferably from about 1.4 to about 9, preferably from about 1.5 to about 8, more preferably from about 2 to about 7.

The multilayer dissolvable solid article of the present invention may have a minimum dimension z of greater than about 3mm but less than about 20cm, preferably from about 4mm to about 10cm, more preferably from about 5mm to about 30 mm.

The multilayer dissolvable solid article described above may comprise more than two such flexible dissolvable porous sheets. For example, it may comprise from about 4 to about 50, preferably from about 5 to about 40, more preferably from about 6 to about 30 of said flexible dissolvable porous sheets. The improved OCF structure in the flexible dissolvable porous sheet prepared according to the present invention allows for stacking many sheets (e.g., 15 to 40) together while still providing a satisfactory overall dissolution rate for the stack.

In a particularly preferred embodiment of the invention, the multilayer dissolvable solid article comprises 15 to 40 layers of the above-described flexible dissolvable porous sheet, and has an aspect ratio ranging from about 2 to about 7.

The multilayer dissolvable solid articles of the present invention may comprise individual sheets of different colors that are visible from the exterior surfaces (e.g., one or more side surfaces) of such articles. Such visible sheets of different colors are aesthetically pleasing to the consumer. Further, the different colors of the individual sheets can provide visual cues indicating the different benefit agents contained in the individual sheets. For example, the multi-layer dissolvable solid article may comprise a first sheet having a first color and comprising a first benefit agent and a second sheet having a second color and comprising a second benefit agent, with the first color providing a visual cue indicative of the first benefit agent and the second color providing a visual cue indicative of the second benefit agent.

The multilayer dissolvable solid articles of the present invention are also advantageous in terms of their ease of use and handling. The individual sheets can be fragile and can cause difficulties during use. In contrast, the multilayer structure can be picked up and handled more easily.

It is also visually appealing as a 3D structure (multilayer) compared to a planar 2D structure (single sheet).

It is particularly desirable in the present invention to incorporate incompatible benefit ingredients into different sheets so that the incompatible benefit ingredients are separated and isolated from each other. For example, aldehyde/ketone containing ingredients (e.g., perfumes) can be separated and sequestered from nucleophilic amine containing ingredients (e.g., aminosilicones and piroctone olamine salts) to avoid undesirable interactions therebetween. In one embodiment of the present invention, a multi-layered dissolvable solid article may comprise a first sheet comprising a fragrance and a second sheet comprising an antimicrobial agent, such as piroctone olamine, and such first and second sheets are preferably characterized by different colors so that they are visually distinguishable from one another. Another advantage is that the coloration may mask any discoloration that may occur during shelf life. More preferably, such a multilayer dissolvable solid article comprises at least one additional sheet between the first sheet and the second sheet, while said at least one additional sheet does not comprise any perfume or piroctone olamine salt. Most preferably, the first sheet and the second sheet are placed as outermost sheets on opposite sides of the multilayer dissolvable solid article.

Furthermore, one or more functional ingredients may be "sandwiched" between individual sheets of a multilayer dissolvable solid article as described above, for example by spraying, sprinkling, dusting, coating, spreading, dipping, injecting, or even vapor deposition. In order to avoid interference of the functional ingredients with the cut or edge seal near the periphery of the individual sheets, it is preferred that the functional ingredients are located in a central region between two adjacent sheets, which is defined as the region spaced from the periphery of the adjacent sheets by a distance of at least 10% of the maximum dimension D. Suitable functional ingredients may be selected from self-cleaning actives (surfactants, free perfumes, encapsulated perfumes, perfume microcapsules, silicones, softeners, enzymes, bleaches, colorants, builders, rheology modifiers, pH adjusters, and combinations thereof) and personal care actives (e.g., emollients, humectants, conditioners, and combinations thereof).

Test method

Test 1: scanning Electron Microscope (SEM) method for determining surface average pore size of sheet product

SEM micrographs of samples were obtained using a Hitachi (TM) 3000 bench-top microscope (S/N: 123104-04). The solid sheet article of the present invention had a sample area of about 1cm × 1cm and was cut from a larger sheet.images were collected at 50X magnification and the unit was operated at 15 kV.A minimum of 5 micrograph images were collected from randomly selected locations on each sample, resulting in a total analysis area of about 43.0mm²Wherein the average pore size is estimated.

The SEM micrographs were then first processed using the image analysis kit in Matlab. The image will be converted to grayscale if desired. For a given image, a histogram of the intensity values of each individual pixel is generated using the 'imhist' Matlab function. Typically, from such a histogram, two separate distributions are apparent, corresponding to pixels of the lighter sheet surface and pixels of the darker areas within the apertures. A threshold value is selected corresponding to the intensity value between the peaks of the two distributions. All pixels with intensity values below the threshold are then set to intensity values of 0 and pixels with higher intensity values are set to 1, resulting in a binary black and white image. The binary images were then analyzed using ImageJ (https:// ImageJ. nih. gov, version 1.52a) to examine pore area fraction and pore size distribution. The scale of each image is used to provide a pixel/mm scale factor. For analysis, each pore is isolated using an automated thresholding and analysis particle function. The output from the analysis function includes the area fraction of the entire image as well as the detected pore area and pore perimeter for each individual pore.

The mean pore diameter is defined as D_A50: 50% of the total pore area has a composition of_APores of hydraulic diameter equal to or less than 50 average diameter.

Hydraulic diameter ═ 4 pore area (m)²) Per hole circumference (m)'.

It is an equivalent diameter and the calculated pores are not all circular.

And (3) testing 2: micro-calculations for determining the overall or regional average pore size and average cell wall thickness of an open-cell foam (OCF) Method of computed tomography (μ CT)

Porosity is the ratio between void space and the total space occupied by the OCF. Porosity can be calculated from μ CT scans by thresholding to segment the void space and determining the ratio of empty voxels to total voxels. Similarly, the Solid Volume Fraction (SVF) is the ratio between solid space and total space, and SVF can be calculated as the ratio of occupied voxels to total voxels. Both porosity and SVF are average scalar values and provide no structural information, such as OCF height-wise pore size distribution, or OCF strut average pore wall thickness.

To characterize the 3D structure of the OCF, the sample is imaged using a μ CT X-ray scanning instrument capable of acquiring datasets with high isotropic spatial resolution. An example of a suitable instrument is a SCANCO system model 50 μ CT scanner (SCANCO medical AG, bruttiselen, Switzerland), which operates with the following settings: the energy level was 45kVp at 133 μ A; 3000 projections; 15mm field of view; 750ms integration time; the average value is 5; and the voxel size is 3 μm per pixel. After the scan and subsequent data reconstruction is complete, the scanner system creates a 16-bit data set, called an ISQ file, in which the gray scale reflects the change in x-ray attenuation, which in turn is related to the material density. The ISQ file is then converted to 8 bits using a scaling factor.

The scanned OCF samples were typically prepared by stamping cores having a diameter of about 14 mm. The OCF punches were laid flat on the low attenuating foam and then mounted in a 15mm diameter plastic cylindrical tube for scanning. A scan of the sample is taken so that the entire volume of all mounted cut samples is included in the dataset. From this larger data set, a smaller sub-volume of the sample data set is extracted from the total cross-section of the scanned OCF, creating a 3D data plate in which the porosity can be assessed qualitatively without edge/boundary effects.

To characterize the pore size distribution and strut size in the elevation direction, a local thickness map algorithm or LTM is implemented on the sub-volume dataset. The LTM method starts with Euclidean Distance Mapping (EDM) which specifies that the gray value is equal to the distance of each empty voxel from its nearest boundary. Based on the EDM data, the 3D void space representing the pores (or the 3D solid space representing the struts) is tessellated into spheres that match the EDM values in size. The voxel surrounded by the sphere is assigned the radius value of the largest sphere. In other words, each empty voxel (or solid voxel of a strut) is assigned a radial value of the largest sphere that fits both the void space boundary (or solid space boundary of a strut) and includes the assigned voxel.

The 3D marker sphere distribution output from the LTM data scan can be viewed as a stack of two-dimensional images in the height direction (or Z direction) and used to estimate the change in sphere diameter from slice to slice as a function of OCF depth. The strut thicknesses are considered to be a 3D data set and the average of all or part of the subvolume can be evaluated. Calculations and measurements were performed using AVIZO Lite (9.2.0) from Thermo FisherScientific and MATLAB (R2017a) from Mathworks.

And (3) testing: percent open cell content of sheet product

The percent open cell content was determined via gas pycnometry. Gas pycnometry is a common analytical technique for accurately determining volume using gas displacement methods. An inert gas such as helium or nitrogen is used as the displacing medium. A sample of the solid sheet product of the present invention is sealed in an instrument compartment of known volume, introduced with a suitable inert gas, and then expanded to another precise internal volume. The pressure before and after expansion was measured and used to calculate the sample article volume.

ASTM standard test method D2856 provides a procedure for determining percent open cell using an older air-to-densitometer model. The device is no longer manufactured. However, the percent open cell can be conveniently and accurately determined by conducting a test using an AccuPyc densitometer from Micromeritics. ASTM procedure D2856 describes 5 methods (A, B, C, D and E) for determining the percent open cell of a foam. For these experiments, samples can be analyzed using Accupyc 1340 using nitrogen and ASTM foampyc software. Method C in the ASTM procedure was used to calculate the percent open cell. The method simply compares the geometric volume determined using thickness and standard volume calculations with the open pore volume measured by Accupyc, according to the following equation:

percent open pore (open pore volume of sample/geometric volume of sample) 100

These assays are recommended to be performed by Micromeritics Analytical Services, Inc. (One Micromeritics Dr, Suite 200, Norcross, GA 30093). More information on this Technology can be found in the Micromeretics Analytical Services website (www.particletesting.com or www.micromeritics.com), or "Analytical Methods in Fine Technology" published by Clyde Orr and Paul Webb.

And (4) testing: final moisture content of sheet product

The final moisture content of the solid sheet product of the present invention was obtained by using a Mettler Toledo HX204 moisture analyzer (S/N B706673091). A minimum of 1g of dried sheet product was placed on the measuring tray. The standard procedure was then performed with additional program settings for 10 minutes analysis time and a temperature of 110 ℃.

And (5) testing: thickness of sheet product

By using a micrometer or thickness gauge such as a disk holder of Mitutoyo Corporation model IDS-1012EA digital micrometer (Mitutoyo Corporation, 965 Corporation Blvd, Aurora, IL, USA60504) to obtain the thickness of the flexible porous dissolvable solid sheet product of the invention. The micrometer has a1 inch diameter platen weighing about 32 grams and measures about 0.09psi (6.32 gm/cm)²) Thickness under pressure is applied.

The thickness of the flexible porous dissolvable solid sheet product was determined by raising the platen, placing a portion of the sheet product on the base under the platen, carefully lowering the platen to contact the sheet product, releasing the platen, and measuring the thickness of the sheet product in millimeters from the digital readout. The sheet product should extend completely to the entire edge of the platen to ensure that the caliper is measured at the lowest possible surface pressure, except in the case of an uneven, more rigid substrate.

And 6, testing: basis weight of sheet product

The basis weight of the flexible porous dissolvable solid sheet product of the present invention was calculated as its weight per unit area (grams/m) of the sheet product²) The solid sheet product of the present invention was cut into sample squares of 10cm × 10cm, so the area was known²To determine the corresponding basis weight.

For an irregularly shaped article, if it is a flat object, the area is therefore calculated based on the area enclosed within the outer perimeter of such an object for a spherical object, the area is therefore calculated based on the average diameter, 3.14 × (diameter/2)²For an irregularly shaped three-dimensional object, the area is calculated based on the side projected onto a flat surface oriented perpendicular to the side having the largest outside dimensionThis is achieved by taking a picture of the delineated area, including the ruler (shaded for comparison) and using image analysis techniques to calculate the area.

And 7, testing: density of sheet product

The density of the flexible porous dissolvable solid sheet article of the present invention is determined by the following equation: the calculated density is the porous solid basis weight/(porous solid thickness × 1,000). The basis weight and thickness of the dissolvable porous solids were determined according to the methods described above.

And (4) testing 8: specific surface area of sheet product

The specific surface area of the flexible porous dissolvable solid sheet article was measured by gas adsorption techniques. Surface area is a measure of the exposed surface of a solid sample at the molecular level. BET (Brunauer, Emmet, and Teller) theory is the most popular model for determining surface area, and it is based on gas adsorption isotherms. Gas adsorption isotherms were determined using physical adsorption and capillary condensation. The technique is summarized by the following steps: the sample is placed in a sample tube and heated under vacuum or flowing gas to remove contaminants on the sample surface. The sample weight was obtained by subtracting the weight of the empty sample tube from the combined weight of the degassed sample and sample tube. The sample tube is then placed in the analysis port and analysis is initiated. The first step in the assay method is to evacuate the sample tube and then use helium gas at liquid nitrogen temperature to determine the free space volume in the sample tube. The sample was then evacuated a second time to remove the helium. The instrument then begins to collect the adsorption isotherm by dosing krypton at user-specified intervals until the desired pressure measurement is reached. The sample can then be analyzed using ASAP 2420 and krypton gas adsorption. These assays are recommended to be performed by Micromeritics Analytical Services, Inc. (One Micromeritics Dr, Suite 200, Norcross, GA 30093). More information on this technology can be found in the micromeretic synthetic Services website (www.particletesting.com or www.micromeritics.com), or in the book "Analytical Methods in Fine particle technology" published by Clyde Orr and Paul Webb.

And (3) testing: rate of dissolution

The dissolution rate of the dissolvable sheet or solid article of the present invention is measured as follows:

1. 400ml of deionized water was added to a 1L beaker at room temperature (25 ℃) and the beaker was then placed on a magnetic stirrer plate.

2. A magnetic stirring bar 23mm in length and 10mm in thickness was placed in water and set to rotate at 300 rpm.

3. The Mettler Toledo S230 conductivity meter was calibrated to 1413. mu.S/cm, and the probes were placed in a beaker with water.

4. For each experiment, the number of samples was chosen such that a minimum of 0.2g of sample was dissolved in water.

5. The data recording function on the conductivity meter was started and the sample was dropped into the beaker. Within 5 seconds, the samples were submerged below the water surface using a flat steel plate with a diameter similar to that of the glass beaker and prevented from floating to the surface.

6. The conductivity was recorded for at least 10 minutes until a steady state value was reached.

7. To calculate the time required to reach 95% dissolution, a 10 second moving average was first calculated from the conductivity data. The time for this moving average to exceed 95% of the final steady state conductivity value was then estimated and taken as the time required to reach 95% dissolution.