Flexible and dissolvable solid sheet article
阅读说明：本技术 柔性且可溶解的固体片材制品 (Flexible and dissolvable solid sheet article ) 是由 陈鸿兴 卡尔·戴维·马克纳马拉 罗伯特·韦恩·小格伦 汤鸣 冈田俊之 于 2019-01-15 设计创作，主要内容包括：本发明题为“柔性且可溶解的固体片材制品”。本文提供了一种柔性且可溶解的固体片材制品,该固体片材制品包含具有50,000道尔顿至400,000道尔顿的重均分子量的PVA聚合物或共聚物,以及选自C<Sub>6</Sub>-C<Sub>20</Sub>直链烷基苯磺酸盐(LAS)、烷氧基化十三烷基聚氧乙烯醚硫酸钠(STS)、以及它们的组合的主要表面活性剂。(The present invention is entitled "flexible and dissolvable solid sheet article". Provided herein is a flexible and dissolvable solid sheet article comprising a PVA polymer or copolymer having a weight average molecular weight of 50,000 to 400,000 daltons, and selected from C 6 ‑C 20 Linear alkyl benzene sulfonate (LAS), sodium alkoxylated trideceth sulfate (STS), and combinations thereof.)
1. A solid article, comprising:
i) from 25% to 70% by weight of the solid article of a first surfactant selected from C6-C20Linear Alkylbenzene Sulfonate (LAS), Sodium Trideceth Sulfate (STS) having a weight average degree of alkoxylation in the range of 0.5 to 5, and combinations thereof; and
ii) from 5% to 40% by weight of the solid article of a second surfactant selected from C having a weight average degree of alkoxylation in the range of from 0.5 to 106-C20Linear or branched Alkyl Alkoxy Sulfates (AAS), C having a weight average degree of alkoxylation in the range of from 5 to 156-C20A linear or branched alkyl Alkoxylated Alcohol (AA), and combinations thereof; and
iii) from 5% to 50% by weight of the solid article of polyvinyl alcohol having a weight average molecular weight of from 50,000 daltons to 400,000 daltons,
wherein the solid article is in the form of a flexible and dissolvable sheet.
2. The solid article of claim 1, comprising from 30% to 65%, preferably from 40% to 60%, by weight of the solid article, of the first surfactant; and wherein preferably the solid article comprises from 10% to 30%, preferably from 15% to 25%, by weight of the solid article, of the second surfactant.
3. The solid article of claim 1 or 2, the solid article packageContains not more than 20%, preferably from 0% to 10%, more preferably from 0% to 5%, most preferably from 0% to 1%, by weight of the solid article, of non-aromatic and non-alkoxylated C6-C20Linear or branched Alkyl Sulfates (AS).
4. The solid article of any one of the preceding claims, comprising from 10% to 40%, preferably from 15% to 30%, more preferably from 20% to 25%, by weight of the solid article, of the polyvinyl alcohol.
5. The solid article of any one of the preceding claims, wherein the polyvinyl alcohol has a weight average molecular weight in the range of from 60,000 daltons to 300,000 daltons, preferably from 70,000 daltons to 200,000 daltons, more preferably from 80,000 daltons to 150,000 daltons; and wherein preferably the polyvinyl alcohol is characterized by a degree of hydrolysis in the range of 40% to 100%, preferably 50% to 95%, more preferably 65% to 92%, most preferably 70% to 90%.
6. The solid article according to any one of the preceding claims, comprising not more than 20%, preferably from 0% to 10%, more preferably from 0% to 5%, most preferably from 0% to 1%, by weight of the solid article, of starch.
7. The solid article according to any one of the preceding claims, further comprising from 0.1% to 25%, preferably from 0.5% to 20%, more preferably from 1% to 15%, most preferably from 2% to 12% of a plasticizer; wherein preferably the plasticizer is selected from the group consisting of glycerin, ethylene glycol, polyethylene glycol, propylene glycol, and combinations thereof; wherein preferably the plasticizer is glycerol.
8. A flexible and dissolvable solid sheet article, comprising: (a) from 10% to 25%, by weight of the solid sheet article, of a polymer having a weight of from 50,000 daltons to 400,000 daltonsPolyvinyl alcohol of average molecular weight; and (b) from 30% to 80%, by weight of the solid sheet article, of one or more surfactants including a primary surfactant selected from C6-C20Linear Alkylbenzene Sulfonates (LAS), Sodium Trideceth Sulfate (STS) having a weight average degree of alkoxylation in the range of 0.5 to 5, and combinations thereof.
9. The flexible and dissolvable solid sheet article according to claim 8, wherein said one or more surfactants further comprises a secondary surfactant selected from the group consisting of C having a weight average degree of alkoxylation ranging from 0.5 to 106-C20Linear or branched Alkyl Alkoxy Sulfates (AAS), C having a weight average degree of alkoxylation in the range of from 5 to 156-C20Linear or branched alkyl Alkoxylated Alcohols (AA), and combinations thereof.
10. The flexible and dissolvable solid sheet article according to claim 8 or 9, wherein said solid sheet article is porous and characterized by:
80% to 100%, preferably 85% to 100%, more preferably 90% to 100% open cell percentage; and/or
An overall average pore diameter of from 100 μm to 2000 μm, 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 solid sheet article; and/or
A thickness of 0.5mm to 4mm, preferably 0.6mm to 3.5mm, more preferably 0.7mm to 3mm, still 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, morePreferably 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 0.2 g/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.
Technical Field
The present invention relates to a flexible and dissolvable solid article comprising polyvinyl alcohol and one or more surfactants.
Background
Flexible and dissolvable wash sheets comprising one or more surfactants and other active ingredients in a water soluble polymeric carrier or matrix are well known. Such sheets are particularly useful for delivering surfactants and other active ingredients when dissolved in water. Such sheets have better structural integrity, are more centralized and easier to store, transport, carry and handle than traditional granular or liquid detergents in the same product category. Such sheets are more flexible and less brittle, and have better sensory appeal to consumers than solid tablet detergents in the same product category.
One challenge facing manufacturers of such flexible and soluble detergent sheets is that there are only limited surfactants available for incorporation into such flexible and soluble detergent sheets due to concerns about the storage stability and film-forming properties of the mixture formed from such surfactants and water-soluble polymeric carriers.
For example, KR101787652 discloses a flexible and dissolvable laundry detergent tablet comprising a polyvinyl alcohol polymer or copolymer as film former, non-aromatic C8-C18Alkali metal alkyl sulfate salts, without any ethylene oxide groups (such as sodium lauryl sulfate) in the structure as primary surfactants, and optionally nonionic surfactants (such as LA7 or LA9) as co-surfactants. In particular, KR10178652 shows that other surfactants such as Linear Alkylbenzene Sulphonate (LAS) or Sodium Lauryl Ether Sulphate (SLES) are associated when used, especially when used as the primary surfactantFilm-forming properties and storage stability are significantly deteriorated.
Such limited surfactant selection severely limits the formulation freedom of such flexible and dissolvable solid sheet products, which in turn may lead to laundry products with suboptimal or less desirable cleaning performance.
Thus, there is a need for flexible and dissolvable solid sheet articles comprising other surfactants that provide improved cleaning performance, but still maintain good film forming characteristics and storage stability.
It would also be advantageous to provide a flexible and dissolvable solid sheet article having improved dissolution characteristics.
It would also be advantageous to provide a more cost effective and easily scalable process for making the above-described improved flexible and dissolvable sheet material.
Disclosure of Invention
In one aspect, the present invention provides a solid article in the form of a flexible and dissolvable sheet comprising:
i) from about 25% to about 70%, preferably from about 30% to about 65%, more preferably from about 40% to about 60%, by weight of the solid article, of a first surfactant selected from C6-C20Linear Alkylbenzene Sulfonate (LAS), Sodium Tridecyl Sulfate (STS) having a weight average degree of alkoxylation in the range of about 0.5 to about 5, and combinations thereof; and
ii) from about 5% to about 40%, preferably from about 10% to about 30%, more preferably from about 15% to about 25%, by weight of the solid article, of a second surfactant selected from the group consisting of C having a weight average degree of alkoxylation in the range of from about 0.5 to about 106-C20Linear or branched Alkyl Alkoxy Sulfates (AAS), C having a weight average degree of alkoxylation in the range of about 5 to about 156-C20A linear or branched alkyl Alkoxylated Alcohol (AA), and combinations thereof; and
iii) from about 5% to about 50%, preferably from about 10% to about 40%, more preferably from about 15% to about 30%, most preferably from about 20% to about 25%, by weight of the solid article, of a polyvinyl alcohol having a weight average molecular weight of 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.
Preferably, the above solid article comprises 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 article, of non-aromatic and non-alkoxylated C6-C20Linear or branched Alkyl Sulfates (AS).
The polyvinyl alcohol used in the present invention is preferably characterized by a degree of hydrolysis in the range of about 40% to 100%, preferably about 50% to about 95%, more preferably about 65% to about 92%, most preferably about 70% to about 90%. More preferably, the solid article of the present invention comprises 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 article, of starch.
Further, the solid article 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. The plasticizer may be selected from the group consisting of glycerin, ethylene glycol, polyethylene glycol, propylene glycol, and combinations thereof. The most preferred plasticizer is glycerol.
In another aspect, the present invention relates to a flexible and dissolvable solid sheet article comprising: (a) from about 10% to about 25%, by weight of the solid sheet article, of polyvinyl alcohol having a weight average molecular weight of from about 50,000 daltons to about 400,000 daltons; and (b) from about 30% to about 80%, by weight of the solid sheet article, of one or more surfactants comprising a primary surfactant selected from C6-C20Linear Alkylbenzene Sulfonates (LAS), Sodium Trideceth Sulfate (STS) having a weight average degree of alkoxylation in the range of from about 0.5 to about 5, and combinations thereof.
Such flexible and dissolvable solid sheet articles may further comprise a secondary surfactant selected from C having a weight average degree of alkoxylation in the range of about 0.5 to about 106-C20Linear or branched Alkyl Alkoxy Sulfates (AAS), C having a weight average degree of alkoxylation in the range of about 5 to about 156-C20Linear or branched alkyl Alkoxylated Alcohols (AA), and combinations thereof.
In a particularly preferred embodiment of the present invention, the flexible and dissolvable solid sheet article is porous and is characterized by one or more of the following parameters:
a percentage open cell content of about 80% to 100%, preferably about 85% to 100%, more preferably about 90% to 100%; and/or
An overall average pore diameter of from about 100 μm to about 2000 μm, from about 150 μm to about 1000 μm, preferably from about 200 μm to about 600 μm; and/or
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 solid sheet article; and/or
A thickness of about 0.5mm to about 4mm, preferably about 0.6mm to about 3.5mm, more preferably about 0.7mm to about 3mm, still more preferably about 0.8mm to about 2mm, most preferably about 1mm to about 1.5 mm; 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
Fig. 1 illustrates a convection-based heating/drying apparatus for making flexible porous dissolvable solid sheets in a batch process.
Fig. 2 illustrates a microwave-based heating/drying apparatus for making a flexible porous dissolvable solid sheet in a batch process.
Fig. 3 illustrates an impingement oven-based heating/drying apparatus for making a flexible porous dissolvable solid sheet in a continuous process.
Fig. 4 illustrates a bottom conduction based heating/drying apparatus for making a flexible porous dissolvable sheet in a batch process.
Fig. 5 illustrates a rotary drum based heating/drying apparatus for making flexible porous dissolvable sheet material in a continuous process.
Fig. 6A shows an SEM image of the top surface of a first flexible porous dissolvable sheet prepared by a method employing a rotating drum based heating/drying apparatus. Fig. 6B shows an SEM image of the top surface of a second flexible porous dissolvable sheet comprising the same composition as the sheet shown in fig. 6A, prepared by a method employing an impingement oven based heating/drying apparatus.
Detailed Description
I. Definition of
As used herein, the term "solid" 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 not restrained and when no external force is applied thereto.
As used herein, the term "flexible" 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.
As used herein, the term "dissolvable" refers to the ability of an article to completely or substantially dissolve in sufficient deionized water without any agitation to leave less than 5 weight percent undissolved residue within eight (8) hours at 20 ℃ and atmospheric pressure.
As used herein, the term "sheet" refers to a non-fibrous structure having a three-dimensional shape, i.e., having a thickness, a length, and a width, with both a length-to-thickness aspect ratio and a width-to-thickness aspect ratio of at least about 5:1, and a length-to-width ratio of at least about 1: 1. Preferably, both the length to thickness aspect ratio and the width to thickness aspect ratio are at least about 10:1, more preferably at least about 15:1, most preferably at least about 20: 1; and preferably the length to width aspect ratio is at least about 1.2:1, more preferably at least about 1.5:1, most preferably at least about 1.618: 1.
As used herein, the term "sulfonate" or "sulfate" refers to a compound that is either in the form of an unneutralized sulfonic acid or sulfuric acid, or in the form of a neutralized salt, or a mixture of both (i.e., partially neutralized).
As used herein, the term "polyvinyl alcohol" or "polyvinyl alcohols" or "PVA" or "PVAs" includes both homopolymers and copolymers of polyvinyl alcohol. The copolymer may comprise vinyl alcohol monomer and one or more of another type of monomer.
As used herein, the term "water soluble" refers to the ability of a sample material of 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, to be completely dissolved or dispersed in water without leaving visible solids or forming a distinct separate phase when such material is placed in one liter (1L) of deionized water at 20 ℃ and sufficiently stirred at atmospheric pressure.
As used herein, the term "starch" refers to both naturally occurring starches 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 which have been crosslinked, acetylated and organically esterified, hydroxyethylated and hydroxypropylated, phosphorylated, and inorganically esterified, cationic, anionic, nonionic, amphoteric, and zwitterionic derivatives thereof, and succinate and substituted succinate derivatives thereof; conversion products derived from any of the starches, including fluid or thin paste starches prepared by oxidation, enzymatic conversion, acid hydrolysis, heating or acid dextrinization, heat treated and/or sheared products are also useful herein; and pregelatinized starches known in the art.
The term "primary surfactant" refers to a surfactant present in a composition in an amount of greater than 50% by weight of the total surfactant content in the composition.
The term "secondary surfactant" refers to a surfactant present in the composition in an amount of no greater than 50% by weight of the total surfactant content in the composition.
As used herein, the term "open-cell foam" or "open-cell structure" refers to a polymer-containing solid communicating matrix that defines a network of spaces or cells that contain a gas, typically a gas (such as air), that does not collapse during the drying process, thereby maintaining the physical strength and cohesiveness of the solid. The interconnectivity of the structure can be described by the percent open porosity, 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 pre-mix sheet is placed during the drying step, while 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 an intermediate 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.
As used herein, the term "aeration (aerate, aerating, or aeration)" refers to a process of introducing a gas into a liquid or paste composition by mechanical and/or chemical means.
As used herein, the term "heating direction" 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 create 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.
As used herein, the term "substantially opposite … …" or "substantially offset from … …" means that there is an offset angle of 90 ° or greater between two directions or lines.
As used herein, the term "substantially aligned" or "substantially aligned" refers to two directions or lines having an offset angle of less than 90 ° between the two directions or lines.
As used herein, the term "primary heat source" refers to a heat source that provides greater than 50%, preferably greater than 60%, more preferably greater than 70%, most preferably greater than 80% of the total heat energy absorbed by the subject (e.g., the aerated wet pre-mix sheet according to the invention).
As used herein, the term "controlled surface temperature" refers to a surface temperature that is relatively consistent, i.e., having less than +/-20% fluctuation, preferably less than +/-10% fluctuation, more preferably less than +/-5% fluctuation.
The term "substantially free of material" means that the indicated material is present at very small levels, is not intentionally added to a composition or product, or is preferably present in such a composition or product at levels that are not analytically detectable. It may include compositions or products in which the indicated material is merely an impurity of one or more of the materials intentionally added to such compositions or products.
It is a surprising and unexpected discovery of the present invention that when a polyvinyl alcohol having a particular weight average molecular weight (i.e., 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 in forming a flexible and dissolvable solid sheet product, the resulting solid sheet product can have "stable" or improved film forming properties even when other surfactants (such as LAS and/or STS) are used as the primary surfactant therein. This discovery reduces or eliminates the need for non-aromatic and non-alkoxylated Alkyl Sulfates (AS) that have relatively poor cleaning performance compared to such other surfactants.
Formulation of the solid sheet of the invention
1.Polyvinyl alcohol (PVA)
As noted above, the flexible and dissolvable solid sheet of the present invention may comprise a polyvinyl alcohol (PVA) polymer or copolymer thereof as a carrier for film formers, structurants, and one or more surfactants and optionally other active ingredients (e.g., emulsifiers, builders, chelating agents, perfumes, colorants, etc.). It is preferred that the PVA polymer or copolymer is present in the flexible and dissolvable solid sheet article of the present invention in an amount in the range of from about 5% to about 50%, preferably 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 present invention, the total amount of PVA(s) present in the flexible and dissolvable solid sheet article of the present invention is no greater than 25% by total weight of such sheet article.
PVA polymers or copolymers suitable for use in the practice of the present invention are selected from those having a weight average molecular weight within 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 sum of the weight average molecular weight of each polymeric raw material times their corresponding relative weight percent based on the total weight of the polymer present in the porous solid.
The flexible and dissolvable solid sheet article of the present invention is preferably prepared by: a wet pre-mix comprising PVA, one or more surfactants and optionally other active ingredients is first formed, then the wet pre-mix is formed into a sheet, and then such wet pre-mix sheet is dried to form a cured sheet article. Correspondingly, the weight average molecular weight of the PVA polymer or copolymer may affect the overall film forming characteristics of the wet pre-mix and its compatibility/incompatibility with the desired surfactant. Furthermore, the weight average molecular weight of the PVA polymer or copolymer used herein may affect the viscosity of the wet pre-mix, which in turn may affect various physical properties of the resulting solid sheet article so formed.
The PVA polymers or copolymers of the present invention are also characterized by a degree of hydrolysis in the range of from about 40% to about 100%, preferably from about 50% to about 95%, more preferably from about 70% to about 92%, most preferably from about 80% to about 90%.
The PVA copolymers of the present invention may comprise vinyl alcohol monomer and one or more of any other type of monomer. Preferred PVA copolymers for use in the practice of the present invention include, in addition to vinyl alcohol monomer and one or more anionic monomers represented by formula (I) and/or (II), the following:
wherein R is1、R2And R3Each independently is H or methyl, and n is independently an integer from 0 to 3. If present, the above anionic monomer units are preferably present in an amount in the range of from about 0.5 mol% to about 5 mol%.
Commercially available polyvinyl alcohols include those from Celanese Corporation (Texas, USA) under the trade name CELVOL, including but not limited to CELVOL 523, CELVOL 530, CELVOL 540, CELVOL 518, CELVOL513, CELVOL 508, CELVOL 504; to be provided with
In addition to PVA as described above, a single starch or a combination of starches may be used as a filler material in an amount that reduces the overall level of PVA required, so long as it helps provide a solid sheet product having the necessary structural and physical/chemical characteristics as described herein. However, excess starch may include the solubility and structural integrity of the solid sheet product. Thus, in a preferred embodiment of the present invention, it is desirable that the solid sheet product comprises no more than 20%, preferably from 0% to 10%, more preferably from 0% to 5%, most preferably from 0% to 1%, by weight of the solid sheet product, of starch.
2.Surface active agent
In addition to the PVA described above, the flexible and dissolvable solid sheet article of the present invention 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.
One benefit of the present invention is that the solid sheet articles of the present invention can be porous and characterized by a unique Open Cell Foam (OCF) structure (described below) that allows for the incorporation of high surfactant levels while still providing rapid dissolution. Thus, highly concentrated cleaning compositions can be formulated into the solid sheet articles of the present invention to provide a new and superior cleaning experience to the consumer. Preferably, the solid sheet article of the present invention comprises 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, of surfactant.
As used herein, surfactants may include surfactants in the conventional sense (i.e., those that provide a foaming effect readily visible to the consumer) and emulsifiers (i.e., those that do not provide any foaming properties but are primarily used as processing aids to prepare 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.
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 paraffin 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 useful in laundry detergent applications. It is a surprising and unexpected discovery of the present invention that when polyvinyl alcohol having a specific weight average molecular weight (as described above) is used as a film former and carrier, LAS can be used as the primary surfactant without adversely affecting the film forming properties and stability of the overall composition. Accordingly, in one embodiment of the present invention, LAS is used as the primary surfactant in solid sheet products. If present, the amount of LAS in the solid sheet articles of the present invention may range from about 25% to about 70%, preferably from about 30% to about 65%, more preferably from about 40% to about 60%, by total weight of the solid sheet article.
Another class of anionic surfactants suitable for use in the practice of the present invention include Sodium Trideceth Sulfate (STS) having 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, whereas EOx refers to a repeating ethylene oxide unit having a repetition number x in the range of 0 to 5, preferably 1 to 4, more preferably 1 to 3, and POy refers to a repeating propylene oxide unit having a repetition number y in the range of 0 to 5, preferably 0 to 4, more preferably 0 to 2. It is to be understood that a material such as ST2S having a weight average degree of ethoxylation of about 2 may, for example, contain a significant amount 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 an overall 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 particular weight average molecular weight (as described above) is used as a film former and carrier, STS can be used as the primary surfactant 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 preparation. If present, the amount of STS in the solid sheet articles of the present invention may range from about 25% to about 70%, preferably from about 30% to about 65%, more preferably from about 40% to about 60%, by total weight of the solid sheet article.
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 of about 6 to about 20 carbon atoms, x is 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, due to non-aromatic and non-alkoxylated C6-C20Compatibility of linear or branched Alkyl Sulfates (AS) with low molecular weight polyvinyl alcohols (e.g., those having a weight average molecular weight of less than 50,000 daltons) in terms of film forming properties and storage stability, thus non-aromatic and non-alkoxylated C6-C20Linear or branched alkyl sulfates are considered as selective surfactants in flexible and soluble solid sheet products, especially as inA primary surfactant. However, it is a surprising and unexpected discovery of the present invention that when polyvinyl alcohols having relatively high weight average molecular weights (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) are used as film formers and carriers, surfactants such as LAS and/or STS, which have superior cleaning performance and low cost, can be used as the primary surfactant in the solid sheet article 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 article having no greater 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 article, of AS.
Another class of anionic surfactants suitable for use in the practice of the present invention comprises C6-C20Straight or branched Alkyl Alkoxy Sulfates (AAS), especially those having a weight average degree of alkoxylation in the range of from about 0.5 to about 10, preferably from about 1 to about 5, more preferably from about 2 to about 4. Within this class, particular preference is given to having the corresponding formula RO (C)2H4O)xSO3M is a linear or branched Alkyl Ethoxy Sulfate (AES) wherein R is an alkyl or alkenyl group of about 6 to about 20 carbon atoms, x is 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 and 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, and 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 AAS (or preferably AES) is a salt comprisingThose of a mixture of 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 article.
Other suitable anionic surfactants include those having the formula [ R ]1-SO3-M]Water soluble salts of organic sulfuric acid reaction products of (2), wherein R1Selected from the group consisting of 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 C10-18The 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 beta-alkoxy alkane sulfonates. These compounds have the formula:
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.
Additional 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 sulfosuccinate; diammonium lauryl sulfosuccinate; tetrasodium N- (1, 2-dicarboxyethyl) -N-octadecyl sulfosuccinate; diamyl esters of sodium sulfosuccinic acid; dihexyl ester of sodium sulfosuccinic acid; and dioctyl esters of sodium sulfosuccinic acid.
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-C18Alkyl ethoxylated alcohols, such as are commercially available from ShellA nonionic surfactant. Other non-limiting examples of nonionic surfactants useful herein 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, such as from BASFC14-C22Mid-chain Branched Alcohols (BA); c14-C22Mid-chain branched alkyl alkoxylates, BAExWherein x is 1 to 30; alkyl polysaccharides, in particular alkyl polyglycosides; polyhydroxy fatty acid amides; and ether-terminated poly (alkoxy) alcohol surfactants. Suitable nonionic surfactants also include those available from BASFName of articleThose that are sold.
In a preferred embodiment, the nonionic surfactant is selected from the group consisting of sorbitan esters and alkoxylated derivatives of sorbitan esters, including sorbitan monolaurate (R) (all available from Uniqema)
The most preferred nonionic surfactants useful in the practice of the present invention comprise C having a weight average degree of alkoxylation in the range of 5 to 156-C20A linear or branched alkyl Alkoxylated Alcohol (AA), more preferably C having a weight average degree of alkoxylation in the range of from 7 to 912-C14A linear ethoxylated alcohol. If present, the amount of one or more AA type nonionic surfactants 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.
In a preferred embodiment of the present invention, the flexible and dissolvable solid sheet article comprises from about 25% to about 70%, preferably from about 30% to about 65%, more preferably from about 40% to about 60%, by weight of the solid sheet article, of the first surfactant which is LAS, STS, or a combination thereof. More preferably, such first surfactant is present as the primary surfactant in the solid sheet article.
In a particularly preferred embodiment of the present invention, the flexible and dissolvable solid sheet article comprises, in addition to the first surfactant described above, from about 5% to about 40%, preferably from about 10% to about 30%, more preferably from about 15% to about 25%, by weight of the solid sheet article, of a second surfactant which is AAS, AA, or a combination thereof.
The flexible and dissolvable solid sheet article of the present invention may further comprise one or more amphoteric surfactants. 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-dodecyl-aminopropionate, sodium 3-dodecylaminopropane sulfonate, sodium lauryl sarcosinate, N-alkyltaurines (such as that prepared by the reaction of dodecylamine with sodium isethionate) and N-higher alkyl aspartic acids.
One class of amphoteric surfactants particularly suitable 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 can be constituted by monoacetates and diacetates. In some types of alkylamphoacetates, the diacetate salt is an impurity or an unintended reaction product. If present, the amount of the one or more alkyl amphoacetates 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 formula:
wherein R is2Alkyl, alkenyl or hydroxyalkyl groups containing from about 8 to about 18 carbon atoms, from 0 to about 10 ethylene oxide moieties, and from 0 to about 1 glyceryl moiety; y is selected from 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 of from about 1 to about 4 carbon atoms, and Z is a group selected from: 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, cocamidopropyl betaine, coco betaine, lauramidopropyl 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, amidobetaines and amidosulfobetaines, wherein RCONH (CH) is2)3Group (wherein R is C)11-C17Alkyl) to the nitrogen atom of the betaine, and may also be used in the present invention.
Cationic surfactants are also useful in the present invention, especially in fabric softener and hair conditioner products. When used to prepare products comprising cationic surfactants as the primary surfactant, it is preferred that such cationic surfactants are present in an amount in the range of 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 may include DEQA compounds, which include a description of diamido actives as well as actives having mixed amido and ester linkages. Preferred DEQA compounds are typically 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-methylhydroxyethylmethyl ammonium sulfate, where the acyl groups are derived from tallow, unsaturated and polyunsaturated fatty acids.
Other suitable actives for use as cationic surfactants include reaction products of fatty acids reacted with dialkylenetriamines, for example, at a molecular ratio of about 2:1, the reaction products comprising compounds of the formula:
R1-C(O)-NH-R2-NH-R3-NH-C(O)-R1
wherein R is1、R2As defined above, and each R3Is C1-6Alkylene groups, preferably ethylene groups. Examples of such actives are tallowic acid, canola oleic acid or reaction products of oleic acid reacted with diethylenetriamine in about a 2:1 molecular ratio, 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 R1An acceptable example of such a structure when being an oleoyl group in commercially available oleic acid derived from either plant or animal sources includes that available from Henkel Corporation223LL 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 name
A second type of DEQA ("DEQA (2)") suitable for use as a cationic surfactant as an active material has 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.
Suitable polymeric surfactants 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 diquaternary ammonium salts, and co-modified amino/polyether siloxanes.
3.Plasticizer
In a preferred embodiment of the present invention, the flexible and dissolvable solid sheet article 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 article.
Suitable plasticizers 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 glycols (especially 200 to 600), propylene glycol, butylene glycol, pentylene glycol, glycerol derivatives (such as propoxylated glycerol), glycidol, cyclohexane dimethanol, hexylene glycol, 2, 4-trimethylpentane-1, 3-diol, pentaerythritol, urea, sugar alcohols (such as sorbitol, mannitol, lactitol, xylitol, maltitol and other mono-and polyhydric alcohols), mono-, di-and oligosaccharides (such as fructose, glucose, sucrose, maltose, lactose, high fructose corn syrup solids and dextrins), ascorbic acid, sorbates, ethylene bismethylamides, amino acids and the like.
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 includeBut 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 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, hydro-starch hydrolysates, other low molecular weight esters (e.g., C.sub.C.sub.2-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 PVA polymer or copolymer, surfactant, and plasticizer, the flexible and dissolvable solid sheet article of the present invention may comprise one or more additional ingredients, depending on its 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 ethylene glycol; lower amine solvents, such as C1-C4Alkanolamines, and mixtures thereof; more specifically 1, 2-propanediol, ethanol, glycerol, monoethanolamine, and triethanolamine), carriers, hydrotropes, builders, chelating agents, dispersants, enzymes, and enzyme stabilizers, catalytic materials, bleaching agents (including photobleaches), and bleach activatorsAgents, 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 (such as 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 (such as benzyl alcohol, methyl alcohol, ethyl ether, hydrolyzed keratin, proteins, plant 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, sequestrants (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, anti-microbial 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). Additional 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 modulators (which function 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, and skin tanning agents, Suspending agents, pH adjusters, pigment particles, antimicrobial agents, insect repellants, shaving lotions, co-solvents or other additional solvents, and the like.
The solid sheet articles of the present invention may also comprise other optional ingredients known to be used or otherwise useful 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 can be formed from the solid sheets of the present invention include laundry detergent products, fabric softening products, hand cleaning products, shampoos or other hair treatment products, body cleaning products, shave preparation products, dish cleaning 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 cleaning products, baby care products, fragrance-containing products, and the like.
The process for making the flexible dissolvable and preferably porous solid sheet articles described above, as well as the process for assembling them into dissolvable multilayer structures of the present invention, are described in detail below.
Overview of the Process for preparing sheets
The flexible and dissolvable solid sheet article of the present invention can be formed by any suitable sheet forming process. Preferably, such sheet forming processes include an aeration step that results in the formation of a porous structure, more preferably an Open Cell Foam (OCF) structure, in the resulting solid sheet article.
For example, WO2010077627 discloses a batch process for forming a porous sheet having an OCF structure, characterized by a percentage open cell content of about 80% to 100%, which serves to improve dissolution. Specifically, a pre-mix of raw materials is first formed, vigorously aerated, and then heat dried in batches (e.g., in a convection oven or microwave oven) to form a porous sheet having the desired OCF structure. While such OCF structures significantly improve the dissolution rate of the resulting porous sheet, there is still a significantly denser and less porous bottom region with thicker cell walls in such sheets. Such a high density bottom region may negatively impact 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.
For another example, WO2012138820 discloses a process similar to WO2010077627, except that continuous drying of the aerated wet premix is achieved by using, for example, 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 the pore structure across different regions thereof. Unfortunately, rate limiting factors still exist in such OCF sheets, such as a top surface with relatively small pore openings and a top area with relatively small pores (i.e., a shell-like top area), which may negatively impact the flow of water therethrough and slow its dissolution.
During the drying step in the above-described 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 of the wet pre-mix, the viscosity of the wet pre-mix, gravity and drying temperature, and the need to balance such processing conditions in order to achieve controlled drainage and form 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 manner (i.e., without a definite direction of heating) during the drying step, or if the direction of heating is substantially aligned with the direction of gravity (i.e., with 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 its thickness direction. In contrast, when the heating direction is offset 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 variation in different regions along the thickness of such sheet. Correspondingly, the latter sheet receives the water flowing through 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 affect pore expansion and pore opening in the solidified pre-mix and produce solid sheets with very different OCF structures. Such differences are more clearly illustrated by fig. 1 to 5 below.
Fig. 1 shows a heating/drying apparatus based on convection. During the drying step, the mould 10 (which may be made of any suitable material such as metal, ceramic or the like)
Figure 2 shows a microwave-based heating/drying apparatus. During the drying step, the mold 30 is filled with an aerated wet pre-mix, which 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 system inc. (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 approximately 12 minutes. Such microwave applicators heat the sheet 32 from within without any definite or consistent heating direction. Correspondingly, 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, although 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 than a sheet formed by a convection-based heating/drying device. 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 openings on the top surface, and the resulting sheet may still have a top surface with relatively small pore openings. Further, 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 3 shows a heating/drying device based on an impingement oven. During the drying step, the
In addition to the above-described heating/drying devices, the present inventors have discovered an improved heating/drying device for drying an aerated wet pre-mixture (a so-called "antigravity" heating/drying device) in which the direction of heating is purposefully configured to counteract/reduce liquid drainage by gravity toward the bottom region (thereby reducing density and improving pore structure in the bottom region) and to 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). These two features serve to improve the overall dissolution rate of the sheet and are therefore desirable.
Fig. 4 illustrates a bottom conduction based heating/drying apparatus for making a flexible porous dissolvable sheet, which is one type of antigravity apparatus according to one embodiment of the present invention. Specifically, the
Fig. 5 illustrates a rotary drum-based heating/drying apparatus for making a flexible porous dissolvable sheet, which is another type of antigravity apparatus according to another embodiment of the present invention. Specifically, the feed tank 60 is filled with an aerated wet pre-mixture 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 it rotates 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-mix 61 forms a thin sheet 62 on the cylindrical heated outer surface of the drum dryer 70, which rotates and dries such aerated wet pre-mix sheet 62 in about 10 to 15 minutes. A leveling blade (not shown) may be placed near the slurry pick-up location to ensure a 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 dry, the sheet 62 may be picked up at the end of the drum rotation, either manually or by a doctor blade 72.
As shown in fig. 5, the sheet 62 formed from the aerated wet pre-mix 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. Correspondingly, 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). Such an outward heating direction forms 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 along a very clear and predictable path (as indicated by the plurality of outwardly extending cross-hatched arrows in fig. 5). 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 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. 5). Thus, during most of the drying step, in a rotary drum based heating/drying apparatus, this slowed rotation and altered heating direction may still act to limit and "counteract"/reduce liquid drainage in the sheet 62 caused by gravity, resulting in improved OCF structure of the sheet so formed. The resulting sheet as dried by heated drum dryer 70 is also characterized by a less dense bottom region having many more uniformly sized holes and a top surface having relatively larger hole openings. In addition, the resulting sheet has a more uniform distribution of overall pore sizes in different regions (e.g., top, middle, bottom) thereof.
In addition to employing an improved heating direction (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 amount of aeration and aeration speed (air feed pump speed, mixing 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, as well as the physical and chemical characteristics of such sheets, is provided in the warranty section.
Method for preparing solid sheet
The present invention proposes to prepare a flexible porous dissolvable solid sheet by the steps of: (a) forming a wet pre-mix comprising raw materials (e.g., PVA polymer or copolymer, surfactant and optionally plasticizer, and any other active ingredients) dissolved or dispersed in water or a 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 wet pre-mix (e.g., by introducing a gas into the wet slurry) to form an aerated wet pre-mix; (c) forming the aerated wet pre-mix into a sheet having opposing first and second sides; and (d) drying the formed sheet preferably in a heating direction forming a temperature gradient that gradually decreases from the first side to the second side of the formed sheet at a temperature of 70 ℃ to 200 ℃ for a drying time of 1 minute to 60 minutes, wherein the heating direction is substantially offset from the gravity direction for more than half of the drying time, i.e. the drying step is performed under heating in a predominantly "antigravity" heating direction. Such a primary "antigravity" heating direction may 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 in fig. 4 and 5 above, respectively.
Step (A): preparation of the Wet premix
The wet premixes of the invention are typically prepared by mixing the solids of interest (including the PVA polymer or copolymer, surfactant, optional plasticizer, and any other active ingredients) with sufficient water or another solvent in a premix tank. A mechanical mixer may be used to form the wet pre-mix. Mechanical mixers useful herein include, but are not limited to, pitched blade mixers or MAXBLEND mixers (Sumitomo Heavy Industries).
Of particular importance in the present invention is the adjustment of the viscosity of the wet pre-mix 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 pre-mix has a significant effect on the pore expansion and pore opening of the aerated pre-mix, and wet pre-mixes with different viscosities can form flexible porous dissolvable solid sheets of very different foam structures. On the one hand, when the wet pre-mix is too thick/viscous (e.g., as at 40 ℃ and 1 s)-1Measured below, having a viscosity above about 25,000 cps), aeration of such wet premixes may become more difficult. More importantly, interstitial liquid drainage from the film bubble facing 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 pre-mix during the subsequent drying step. As a result, the flexible porous dissolvable solid sheets formed thereby 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)-1Measured below, having a viscosity of less than about 1,000 cps), the aerated wet pre-mix may not be stable enough, i.e., the air bubbles in the wet pre-mix may collapse, or coalesce too quickly after aeration and before drying. Thus, the resulting solid sheet may be much less porous and denser than desired.
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, as measured below. Using a Malvern Kinexus Lab + rheometer with a cone-plate geometry (CP1/50 SR3468 SS), a gap width of 0.054mm, a temperature of 40 ℃ and 1.0s-1The shear rate of (c) for a period of 360 secondsThe premix viscosity value was measured.
In a preferred, but not necessary, embodiment, the solids of interest are present in the wet pre-mix 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 pre-mix. Percent solids is the sum of the weight percentages of all solid components, semi-solid components, and liquid components, excluding water and any significant volatiles 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 pre-mix is too low, the viscosity of the wet pre-mix may decrease to a level that will result in bubble collapse/coalescence and a more porous structure shrinkage percentage (%) during drying, which results in a significantly less porous and denser solid sheet.
In the solids of interest in the wet premixes of the invention, there may be present from about 10% to about 75% surfactant, from about 0.1% to about 25% PVA polymer or copolymer, 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.
Preferably, the wet pre-mix used comprises from about 3% to about 20% PVA by weight of the wet pre-mix, in one embodiment from about 5% to about 15% PVA by weight of the wet pre-mix, and in one embodiment from about 7% to about 10% PVA by weight of the wet pre-mix.
More preferably, the wet pre-mix comprises from about 10% to about 40% of one or more surfactants by weight of the wet pre-mix, in one embodiment from about 12% to about 35% of one or more surfactants by weight of the wet pre-mix, and in one embodiment from about 15% to about 30% of one or more surfactants by weight of the wet pre-mix.
Still more preferably, the wet pre-mix comprises from about 0.02% to about 20% by weight of the wet pre-mix of a plasticizer, in one embodiment from about 0.1% to about 10% by weight of the wet pre-mix of a plasticizer, and in one embodiment from about 0.5% to about 5% by weight of the wet pre-mix of a plasticizer.
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 utilized prior to the aeration step. Furthermore, additional heat may be applied during the aeration process in an attempt to maintain the wet pre-mix at such high temperatures. This may be accomplished via conductive heating from one or more surfaces, injection of steam, or other processing means. It is believed that the act of pre-heating the wet pre-mix before and/or during the aeration step may provide a means for reducing the viscosity of the pre-mix containing a higher percentage of solids for improved introduction of gas bubbles into the mixture and formation of the desired solid sheet. It is desirable to achieve a higher percent solids as this can reduce the overall energy required for drying. Thus, an increase in percent solids may conversely result in a decrease in water content 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 such viscosity increases and thus allow the manufacture of fast dissolving sheets even when high solids content premixes are used.
Step (B): aeration of wet premixture
Aeration of the wet pre-mix is carried out so as to introduce a sufficient amount of gas bubbles into the wet pre-mix and subsequently form OCF structures therein upon drying. Once fully aerated, the wet pre-mix is characterized by a density that is significantly lower than that of either an unaerated wet pre-mix (which may contain some inadvertently trapped air bubbles) or an insufficiently aerated wet pre-mix (in which some air bubbles may be contained but the volume percentage is much lower and the air bubble size is significantly larger). Preferably, the aerated wet pre-mix 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 achieved by physical or chemical means in the present invention. In one embodiment, the gas may be introduced into the wet pre-mix by mechanical agitation, for example, by using any suitable mechanical processing device, 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 via chemical means, for example, by providing in situ gas formation via 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 pre-mix can be achieved cost effectively by using a continuous pressurized aerator or mixer conventionally used in the manufacture 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 mix head speeds set at about 300 to 800 (preferably about 400 to 600) and air flow rates of about 50 to 150 (preferably 60 to 130, more preferably 80 to 120), respectively. As another example, the Oakes continuous automatic mixer may be operated at a mix head speed setting of about 10 to 30rpm (preferably about 15 to 25rpm, more preferably about 20rpm), with an air flow rate of about 10 to 30 liters per hour (preferably about 15 to 25L per hour, more preferably about 19 to 20L per hour).
In another specific embodiment, aeration of the wet pre-mix may be achieved by using a spinbar as part of a rotary drum dryer, more specifically a feed chute, wherein the wet pre-mix is stored before it is coated onto the heated outer surface of the drum dryer and dried. The spinbar is typically used to agitate the wet premix 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 about 150rpm to about 500rpm, preferably about 200rpm to about 400rpm, more preferably 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 mentioned above, the wet pre-mix may be maintained at an elevated temperature during the aeration process in order to adjust the viscosity of the wet pre-mix for optimal aeration and to control 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 of the spinning bar (when the rotating drum is stationary), and then heated to about 70 ℃ as the rotating drum heats up and begins to rotate.
The bubble size of the aerated wet pre-mix helps to achieve a uniform layer in the OCF structure of the resulting solid sheet. In one embodiment, the bubble size of the aerated wet pre-mix is 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 formation
After sufficient aeration, the aerated wet pre-mix forms 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 pre-mix may be formed into a sheet by: (i) casting it into shallow cavities or trays or specially designed sheet molds; (ii) extruding it onto a continuous belt or screen of a dryer; (iii) it is applied to 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 formed aerated wet pre-mix sheet has a thickness in the following range: a thickness in the range of 0.5mm to 4mm, preferably 0.6mm to 3.5mm, more preferably 0.7mm to 3mm, still more preferably 0.8mm to 2mm, most preferably 0.9mm to 1.5 mm. Controlling the thickness of such formed aerated wet pre-mix sheets can be important to ensure that the resulting solid sheet has 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 thickness of the resulting solid sheet. If too many, such through-holes can significantly compromise both the overall structural integrity and aesthetic appearance of the sheet. If the formed sheet is too thick, not only does it take 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, as 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 the multilayer structures of the present invention having the desired aspect ratio, while still providing a satisfactory pore structure for rapid dissolution and ensuring effective drying in a relatively short drying time.
Step (D): drying under antigravity heating
Preferably, but not necessarily, the present invention employs a countergravity heating direction during the drying step, 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 countergravity heating directions can reduce or counteract excess interstitial liquid drainage toward 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 air 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 air bubbles are no longer able to expand or form surface openings). Thus, solid sheets formed by drying with such countergravity heating are characterized by improved OCF structures that enable 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. 4. For example, an aerated wet pre-mix 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 flat 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 ℃. The thermal energy is transferred from the flat heating surface to the bottom surface of the aerated wet pre-mix sheet via conduction, so that the curing of the sheet starts from the bottom zone and gradually moves upwards to finally reach the top zone. To ensure that the direction of heating during this process is predominantly antigravity (i.e. substantially offset from the direction of gravity), 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 antigravity heating direction is provided by a rotary drum based heating/drying apparatus, also known as drum drying or drum drying, similar to that shown in fig. 5. Drum drying is a contact drying process for drying a liquid from a viscous premix of raw materials at relatively low temperatures on the outer surface of a heated rotatable drum (also known as a drum or cylinder) to form a sheet-like article. This is a continuous drying process, particularly suitable for bulk drying. Because drying is performed via contact heating/drying at relatively low temperatures, it is generally energy efficient and does not adversely affect the compositional integrity of the raw materials.
The rotatable cylinder used for heating in drum drying is internally heated, for example by steam or electricity, and is rotated at a predetermined rotational speed by a motorized drive mounted on a 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 on 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 the sheet-forming process.
A feed mechanism is also provided on the base support for feeding the aerated wet raw material premix as described above onto the heated rotatable drum to form a thin layer of viscous premix on the outer surface of the heated rotatable drum. Thus, such thin layers of the premix are dried by the heated rotatable drum via contact heating/drying. The feed mechanism includes a feed chute mounted on the base support 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 in order to meet the material requirements of speed and quality. The feed tank may also include a spinning bar for agitating the wet pre-mix therein prior to application to the outer surface of the heated rotatable cylinder to avoid phase separation and settling. As noted above, such a spinbar can also be used to aerate the wet premix as desired.
A heating cover can be arranged on the base support to prevent quick 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. Suction means are also mounted on the heating hood for sucking the hot steam to avoid any condensation water from 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 conveying 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 a 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 pre-mix comprising all or some of the raw materials used to make the flexible porous dissolvable solid structural article to the outer surface of the heated rotatable drum to form thereon a thin layer of the aerated wet pre-mix having the desired thickness as described in the previous section above. Optionally, the suction device 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 pre-mix after drying at a relatively low temperature (e.g., 130 ℃) by a heated rotatable drum. Without such a static scraping mechanism, the dried/cured sheet can also be peeled off manually or automatically and then rolled up by a roller.
The total drying time in the present invention depends on the formulation and solids content of 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 substantially opposite to the gravity direction for more than half of the drying time, preferably more than 55% or 60% of the drying time (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 aerated wet pre-mix sheet can 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 51% to 99% (e.g., 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 means not shown herein, for example, by an elongated heating band of serpentine shape that can be rotated along a longitudinal central axis.
V. physical characteristics of solid sheet
The flexible porous dissolvable solid sheet formed by the above processing steps, particularly by using a countergravity heating/drying device, may be characterized by an improved pore structure that allows water to enter the sheet more easily and the sheet to dissolve in water more quickly. Such improved pore structure can be readily achieved by adjusting various processing conditions as described above.
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) an overall average pore size 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
The solid sheet of the present invention has opposing top and bottom surfaces, and the top surface thereof is preferably characterized by a surface average pore size of greater than about 100 μm, more preferably greater than about 110 μm, still more preferably greater than about 120 μm, still more preferably greater than about 130 μm, and most preferably greater than about 150 μm, as measured by the SEM method described in test 1 below. The solid sheet formed by the antigravity heating/drying apparatus (e.g., bottom conduction-based or rotating drum-based apparatus) has a significantly larger surface average pore size at its top surface (as shown in fig. 6A-6B, which is described in detail in example 2 below) when compared to the solid sheet formed by the non-antigravity heating/drying apparatus (e.g., convection-based, microwave-based, or impingement oven-based apparatus), because under antigravity heating, the top surface of the formed aerated wet pre-mix sheet is final dried/cured, and the bubbles near the top surface have the longest expansion time and form larger pore openings at the top surface.
Further, solid sheets formed by the countergravity heating/drying devices described herein are characterized by a more uniform pore size distribution between different regions along the thickness direction thereof as compared to sheets formed by non-countergravity heating/drying devices. Specifically, the solid sheet formed by the antigravity heating/drying apparatus includes a top region adjacent to the top surface, a bottom region adjacent to the bottom surface, and an intermediate region between the top region and the bottom region, with the top region, the intermediate region, and the bottom region all having the same thickness. Each of the top, middle, and bottom regions of such solid sheets is characterized by an average pore size, while the ratio of the average pore size of the bottom region to the average pore size of 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 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 2 below). Further, the solid sheet formed by the antigravity heating/drying apparatus may be characterized by a bottom to middle average pore diameter 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 diameter 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.
Further, the relative standard deviation (RSTD) between the average pore diameters of the top, middle and bottom regions of the solid sheet formed by the antigravity heating/drying apparatus 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 impingement oven-based heating/drying devices can have a relative standard deviation (RSTD) between top/middle/bottom mean pore diameters of greater than 20%, possibly greater than 25% or even greater than 35% (as shown in example 2 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
The solid sheet of the present invention may contain a small amount 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 can ensure the desired flexibility/deformability of the sheet, as well as provide 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 in the range of about 0.6mm to about 3.5mm, preferably about 0.7mm to about 3mm, more preferably about 0.8mm to about 2mm, most preferably about 1mm to about 1.5 mm. The thickness of the solid sheet can be measured using test 5 described below. The solid sheet after drying may be slightly thicker than the aerated wet pre-mix sheet due to the expansion of the pores which in turn leads to an overall volume expansion.
The solid sheets of the present invention may also be characterized by a basis weight of about 50 grams/m2To about 250 g/m2Preferably about 80 g/m2To about 220 g/m2And more preferably about 100 grams/m2To about 200 g/m2As measured by test 6 described below.
Further, the solid sheet of the present invention may have a thickness of 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/cm3Density within the range, as measured by test 7 below. The density of the solid sheet of the present invention is lower than that of the aerated wet pre-mix sheet, also due to the expansion of the pores which in turn leads to an overall volume expansion.
Further, the solid sheet of the present invention may be characterized by a specific surface area of about 0.03m2G 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 0.18m2(iv)/g, as measured by test 8 described below. The specific surface area of the solid sheet of the present invention 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.
Assembling a plurality of sheets into a multilayer dissolvable solid article
Once the flexible dissolvable porous solid sheet as described above is formed, two or more of such sheets can be further assembled together to form a multilayer dissolvable solid article, as described above. Such multilayer dissolvable solid articles may 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 and/or 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., they are used to convert two or more flexible dissolvable porous sheets of the present invention into dissolvable solid articles having a desired three-dimensional shape.
The surprising and unexpected discovery of the present invention is that the three-dimensional (3-D) 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 percent open cell content of about 80% to 100% and an overall 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 multilayer structure to extend significantly in the thickness direction to form 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, the multilayer dissolvable solid article of the present invention formed by stacking together multiple layers of the above-described flexible dissolvable porous sheets is characterized by a maximum dimension D and a minimum dimension z (the minimum dimension being perpendicular to the maximum dimension D), while the ratio of D/z (hereinafter also referred to as "aspect ratio") is 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 can 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. 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 can 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 sheet. The improved OCF structure of the flexible dissolvable porous sheet prepared according to the present invention allows 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 present invention, the multilayer dissolvable solid article comprises 15 to 40 layers of the above-described flexible dissolvable porous sheet, and has an aspect ratio in the range of 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 surface (e.g., one or more side surfaces) of such articles. Such visible sheets of different colors are aesthetically pleasing to consumers. Further, the different colors of the individual sheets can provide visual cues indicating the different benefit agents contained in the individual sheets. For example, a multi-layer dissolvable solid article can 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.
Furthermore, one or more functional ingredients may be "sandwiched" between separate sheets of a multilayer dissolvable solid article as described above, for example by spraying, sprinkling, dusting, coating, spreading, dipping, injecting, or even vapor deposition. To avoid interference of such functional ingredients with the cut or edge seal near the periphery of an individual sheet, it is preferred that such functional ingredients are located in a central region between two adjacent sheets, which region is defined as being spaced apart from the periphery of such 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 articles
SEM micrographs of samples were taken 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 about 43.0mm2The average pore size on each sample was 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 single pixel is generated using the "imhist" Matlab function. Typically, from such a histogram, two independent distributions are apparent, corresponding to pixels of the lighter sheet surface and pixels of the darker areas within the holes. 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 image was then analyzed using ImageJ (https:// ImageJ. nih. gov, version 1.52a) to examine both pore area fraction and pore size distribution. The scale of each image is used to provide a pixel/mm scale factor. For analysis, each well was isolated using automated thresholding and analytical particle functions. The output of the analysis function includes the area fraction of the overall image as well as the detected hole area and hole perimeter for each individual hole.
The average pore diameter is defined as DA50: 50% of the total pore area is defined byA50 pores of equal or smaller average diameter hydraulic diameter.
Hydraulic diameter ═ 4 pore area (m)2) Hole perimeter (m) ".
It is an equivalent diameter and the holes calculated 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 via thresholding to segment the void space and determining the ratio of void 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 that do not provide structural information such as pore size distribution in the height direction of the OCF or average pore wall thickness of the OCF struts.
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
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, smaller sub-volumes of the sample data set are extracted from the total cross-section of the scanned OCF, creating a 3D data plate in which the wells can be qualitatively assessed 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 begins with a Euclidean Distance Map (EDM) that specifies gray level values equal to the distance of each empty voxel from its nearest boundary. Based on the EDM data, the 3D void space representing the hole (or the 3D solid space representing the struts) is tessellated into spheres that match in size the EDM values. 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 pore content of sheet product
The percent open cell content was measured via gas pycnometry. Gas pycnometry is a common analytical technique for accurately measuring volume using a gas displacement method. An inert gas such as helium or nitrogen is used as the displacing medium. Samples of the solid sheet products of the present invention were sealed in an instrument compartment of known volume, introduced with an appropriate 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 versus densitometer model. The device is no longer manufactured. However, the percent open porosity can be conveniently and accurately determined by performing 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 were analyzed using nitrogen and ASTM foampyc software using Accupyc 1340. Method C in the ASTM procedure was used to calculate the percent open cell. The method simply compares the geometric volume as measured using thickness and standard volume calculations with the open pore volume as measured by Accupyc, according to the following equation:
percent open pore (open pore volume of sample/geometric volume of sample) 100
These measurements are recommended to be made by Micromeritics Analytical Services, Inc. (One Micromeritics Dr, Suite 200, Norcross, GA 30093). More information about 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. A standard procedure was then performed with the additional procedure set to 10 minutes analysis time and a temperature of 110 ℃.
And (5) testing: thickness of sheet product
The thickness of the flexible porous dissolvable solid sheet product of the present invention is obtained by using a micrometer or thickness gauge such as a disk-based digital micrometer from Mitutoyo Corporation model IDS-1012E (Mitutoyo Corporation,965 Corporation Blvd, Aurora, IL, USA 60504). The micrometer has a 1 inch diameter platen weighing about 32 grams, which measures about 0.09psi (6.32 gm/cm)2) Thickness under pressure.
The thickness of the flexible porous dissolvable solid sheet product was measured 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 thickness is measured at the lowest possible surface pressure, except in the case of a more rigid substrate that is not flat.
And 6, testing: basis weight of sheet product
Basis weight of the flexible porous dissolvable solid sheet article of the present invention is calculated as the weight per unit area of the sheet article (grams/m)2) 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 based onThus for a spherical object, the area is calculated based on the average diameter to be 3.14 × (diameter/2)2This can be accomplished by carefully tracing the external dimensions of the object with a pencil onto a piece of drawing paper, and then by roughly pointing out a square number and multiplying by the known square area, or by taking a picture of the traced area (shaded for comparison) including a ruler and calculating the area using image analysis techniques.
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 formula: the calculated density is the basis weight of the porous solid/(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 is measured via 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 measured 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 total 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 analysis method is to evacuate the sample tube and then measure the free space volume of the sample tube using helium gas at liquid nitrogen temperature. The sample was then evacuated a second time to remove the helium. The instrument then begins to collect the adsorption isotherms by dosing krypton at user-specified intervals until the desired pressure measurement is achieved. The sample can then be analyzed using ASAP 2420 and krypton gas adsorption. These measurements are recommended to be made by Micromeritics Analytical Services, Inc. (One Micromeritics Dr, Suite 200, Norcross, GA 30093). More information about 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 stir bar having a length of 23mm and a thickness of 10mm 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 probe was placed in water in a beaker.
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 activated and the sample was dropped into the beaker. Within 5 seconds, the samples were submerged below the water surface using a flat steel plate similar in diameter to a 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 achieve 95% dissolution.
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