阅读说明：本技术 用于可再生硬质泡沫的组合物和方法 (Compositions and methods for renewable rigid foams ) 是由 格雷戈里·M·格伦 金星 冈特·默多克 于 2020-03-30 设计创作，主要内容包括：一种组合物,包含纤维组分、至少一种表面活性剂/发泡剂、至少一种分散剂和任选的至少一种粘合剂,其中纤维组分形成这样的粘性混合物,即一旦粘性混合物达到预定的干燥度,在加入表面活性剂/发泡剂后该粘性混合物就转化为泡沫产品,其中泡沫产品在干燥过程中抗收缩并保持硬质。(A composition comprising a fibrous component, at least one surfactant/foaming agent, at least one dispersant and optionally at least one binder, wherein the fibrous component forms a viscous mixture that upon addition of the surfactant/foaming agent converts to a foamed product once the viscous mixture reaches a predetermined dryness, wherein the foamed product resists shrinkage and remains rigid during drying.)

1. A composition comprising a fibrous component, at least one blowing agent, at least one dispersant, and optionally at least one binder, wherein the fibrous component forms a viscous mixture that upon addition of the blowing agent converts to a foam product once the viscous mixture reaches a predetermined dryness, wherein the foam product resists shrinkage and remains rigid during drying.

2. The composition of claim 1, wherein the fiber component is selected from the group consisting of at least one complex carbohydrate of plant origin, crop waste fiber, wood, lignocellulosic fiber material, fiber crops, and combinations thereof.

3. The composition of claim 1, wherein the binder is distributed substantially throughout the fiber component to produce a fiber matrix.

4. The composition of claim 1, wherein the binder is selected from the group consisting of polyvinyl alcohol, starch, gums, alginates, sodium silicate, and combinations thereof.

5. The composition of claim 1, wherein the binder is a native starch.

6. The composition of claim 1, wherein the foaming agent is SDS.

7. The composition of claim 1, wherein the binder is polyvinyl alcohol and is present in an amount of 0.5 wt% to about 10 wt% of the foam product.

8. The composition of claim 1, wherein the dispersant is selected from the group consisting of polyvinyl alcohol, pregelatinized starch, carboxymethyl cellulose and its derivatives, hydroxymethyl cellulose and its derivatives, water-soluble viscosity modifiers, vegetable gums, and combinations thereof.

9. The composition of claim 1, wherein the viscous mixture has a predetermined viscosity.

10. The composition of claim 1, further comprising increased thermal insulation properties.

11. The composition of claim 1, further comprising increased sound damping properties.

12. The composition of claim 1, wherein the foam product is rigid and stable.

13. The composition of claim 1, wherein the foam product, after drying, is at least about 95% of its pre-dried size.

14. The composition of claim 1, wherein the composition comprises at least one binder.

15. A method of making a foam composition, the method comprising mixing a fiber component in water to produce hydrated fibers; excess water is removed and the fibers are mixed with at least one dispersant and optionally at least one binder, followed by the incorporation of at least one blowing agent to produce a foam composition.

16. The method of claim 15, comprising mixing the fiber components in water to produce hydrated fibers; excess water is removed and the fibers are mixed with at least one dispersant and at least one binder, followed by the incorporation of at least one blowing agent to produce a foam composition.

17. The method of claim 14, wherein the fiber is a fiber pulp.

18. The method of claim 14, wherein the binder is selected from gelatinized starch slurry and pregelatinized starch powder.

19. An article made from the composition of claim 1.

20. An article made from the composition of claim 1, wherein the article is compression molded.

21. A composition comprising a fibrous component, at least one blowing agent, at least one dispersant, and optionally at least one binder, wherein the fibrous component forms a viscous mixture that upon addition of the blowing agent converts to a foam product once the viscous mixture reaches a predetermined dryness, wherein the foam product resists shrinkage and remains rigid during drying; wherein the composition is prepared by a process comprising the steps of: mixing the fiber components in water to produce hydrated fibers; excess water is removed and the fibers are mixed with at least one dispersant and optionally at least one binder, followed by the incorporation of at least one blowing agent to produce a foam composition.

22. The composition of claim 21, wherein the composition comprises a fibrous component, at least one foaming agent, at least one dispersant, and at least one binder, wherein the fibrous component forms a viscous mixture that upon addition of the foaming agent converts to a foam product once the viscous mixture reaches a predetermined dryness, wherein the foam product resists shrinkage and remains rigid during drying; wherein the composition is prepared by a process comprising the steps of: mixing the fiber components in water to produce hydrated fibers; excess water is removed and the fibers are mixed with at least one dispersant and at least one binder, followed by the incorporation of at least one blowing agent to produce a foam composition.

Technical Field

The present invention relates to biodegradable foam compositions made from renewable resources and methods of making such compositions. More particularly, the present invention relates to biodegradable rigid foam compositions and methods of making articles such as containers, packages, and sheets from such compositions.

Background

Foam materials are important in many industrial areas. Foaming not only imparts useful mechanical and insulating properties to the product, but also reduces costs by reducing the amount of material required. For example, polyurethane foams (PUFs) have become a nearly $ 540 billion industry in the United states (see, e.g., J. moon et al, Synthesis of polyurethane foam from inorganic waterborne crosslinked polyurethane foam automotive seat concepts, Washe Management, 85:557-562 (2019)). Other common foam products are made from Polyethylene (PE) and Polystyrene (PS). Foams based on various PUFs, PE and PS are commonly used for building insulation and many other applications such as mattresses, shoes and helmets (see, for example, L.Aditya et al, A review on insulation materials for Energy conservation in building, Recewable and Sustainable Energy Reviews, 73: 1352-. Extruded polystyrene (XPS) and molded polystyrene (EPS) have also been widely used for disposable, single use products such as coffee cups, trays, bowls, trays, cartons and takeaway food containers, as well as packaging materials for temperature and impact protection (see, for example, N. Chaukura et al, patent uses and value-added products derived from a water polyethylene in packaging units: A review, Resources, 107: 157-. Although XPS and EPS foam are lightweight, inexpensive, and have excellent properties (e.g., high heat resistance, moisture resistance, and impact resistance), it is not compostable or biodegradable, which is particularly problematic when used in snack and beverage containers, which are often mishandled and can accumulate in waterways, beaches, roadsides, and many other areas. Accordingly, there is an increasing demand for food and beverage containers and protective packaging made from renewable, compostable materials. Some large cities have banned the use of polystyrene foam containers, which further exacerbates this need.

Containers and other packaging materials are typically designed to protect items from external damage (e.g., moisture, shock, crushing, vibration, leakage, spillage, gas, light, extreme temperatures, contamination, animal and insect intrusion, etc.) and may also contain information about the items therein. For example, these materials are widely used around the world, from protective packaging materials for shipping to plates and cups designed for the food and beverage industry. The concept of single-use food and beverage containers, particularly as an inexpensive, hygienic and convenient alternative to the reusable type, has increased nearly five times since 1960. The value of single-use food and beverage containers in the areas of human health and improved hygiene has often been overlooked in discussing their use as a convenience facility and as an important source of pollution and municipal solid waste. Various types of plastics (e.g., polystyrene, polyethylene terephthalate, polypropylene, high density polyethylene, low density polyethylene, polycarbonate, etc.) are common and have the advantages of ease of manufacture, light weight, low cost, and inherent moisture and oil resistance. Polystyrene is a popular and widely used plastic for heat and impact protection of shipping products and take-away food containers, etc., because, for example, it is easy to form polystyrene foam. It is estimated that 0.83MMT polystyrene trays and cups were used in 2012 and discarded as Municipal Waste (see, e.g., EPA, u., bacterial Solid water Generation, Recycling, and dispensing in the United States: Facts and regulations for 2012).

Reducing the environmental footprint of disposable packaging is a social challenge, as polystyrene foam, in particular, is generally rarely reused or recycled. Interest in sustainable solutions has prompted the development of products made from renewable materials including starch, polylactic acid, and polyhydroxybutyrate, among others, and in addition, these materials continue to be developed as sustainable materials for various containers, including containers for food and beverages (see, for example, Farah, s. et al, Advanced drug delivery reviews, 107:367 (2106); wideastti, i. et al, AIP Conference Proceedings, 2016; AIP Publishing: 2016; p 030020;m. et al, European Food Research and Technology, 242: 815-; arrieta, M. et al, Multifunctional Polymeric Nanocomposites Based on cellular Reinforcements, 205 (2016)).

Plant-based materials such as cellulose are desirable in part because they are renewable and relatively low cost. Cellulose is the most abundant polymer on earth, as it is a major structural element of all plants. There are large areas dedicated to growing crops such as corn, wheat, soybeans, and natural pasture, as well as forests where cellulose may be harvested. In addition to building wood, wood is also processed into fibre pulp for paper and cardboard (cardboard) by heating in an aqueous slurry containing chemical additives. The pulping process removes part of the lignin and hemicellulose that binds the cellulose fibers in the wood together, making it easier to disperse the fibers into a fine suspension. The prices of pulp and paper vary widely, but are generally lower than those of commercial petroleum-based polymers, which makes lignocellulosic materials economically attractive as alternatives to petroleum-based plastics.

The use of such Biodegradable and/or sustainable Materials in consumer products continues to expand in various industrial fields, including packaging, construction, agriculture and personal hygiene (see, for example, T.Huber et al, A critical review of all-cellular composites, Journal of Materials Science, 47(3): 1171-a 1186 (2012); K.G.Satyananayana et al, Biodegradable composites based on lignocellulosic fibers-An overview, Progress in polymer Science, 34(9): 982-a 1021 (2019)). In certain applications, plant fibers are considered to be an important and inexpensive alternative to petroleum-based products and other non-renewable products (see, e.g., M.J. John and S.Thomas, Biofibers and biomolysis, Carbohydrate polymers, 71(3):343-364 (2008); N.Abilash and M.Sivapragsh, Environmental fibers of eco-friendly natural fiber for formed polymeric compositions, International Journal of Application or Innovation in Engineering & Management, 2(1):53-59 (2013)). Recent research has focused on improving the processes used to make: wet fiber foams (see, for example, U.S. Pat. No. 6,500,302), fiber networks with large pore sizes for tissue (tissue) production (see, for example, a.m. al-Qararah et al, explicit pore size distribution in foam-formed fiber networks, normal pure and Paper Research Journal,27(2):226(2012)), very low density Cellulose foams (see, for example, a.madani et al, Ultra-high weight Paper foams: processing and properties, Cellulose 21(3): 2023-. Foam forming technology facilitates the production of paper and paperboard with improved properties (see, for example, j. poranen et al, Breakthrough in paper manufacturing resource with foam forming, 2013). The use of fibrous foams for thermal and acoustic insulation is also of commercial interest. Insulation of cellulose loose fill or cellulose batting is used for home insulation as an alternative to fiberglass batting insulation. However, conventional cellulose-based foams are generally not as rigid as, for example, PS foams.

Most compostable foam technologies (e.g., cellulose fiber foams) have cost or technical limitations that have led to the continued widespread use of traditional plastic-based foams in packaging and food service and other applications. The foam pad is manufactured by a predetermined manufacturing method. The method first involves suspending the fibers in a dilute aqueous solution containing a surfactant (see, e.g., O.Timofeev et al, Drying of foam-formed materials from virgin fiber fibers, Drying technology,34(10):1210-1218 (2016)). Air is introduced by high speed mixing to convert the mixture into a foam, and the resulting foam is then formed into a pad which is dewatered by drainage (drainage). Drainage may be facilitated by the use of a vacuum, moderate compression, or other force. Gravity and capillary forces within the fiber mat can affect drainage and fluid flow. When capillary pressure, gravity, mechanical pressure, vacuum and other forces are balanced, drainage balance is achieved. At this point, the volume of liquid within the foam is generally constant, requiring a drying section to further reduce the liquid content. Furthermore, the foam structure may be lost if external mechanical pressure is applied. Although cellulose fiber foam is a sustainable material made from plant fibers, the traditional process starts with foam with excessive water content and causes significant shrinkage of the final product during processing.

The existing process for making cellulosic foam from wet foam is to make very low density foam: (>0.02g/cm³) The aspect is effective. However, foamsAre not rigid and the process is not suitable for making products of the quality required for commercial use. For example, a large amount of water used for manufacturing the foam requires a long dehydration step, and in addition, the foam may shrink significantly during the dehydration step, making the foam dimensionally unstable. A large amount of blowing agent or any other additive is also lost in the dewatering step.

Thus, there is a continuing need for low cost compostable rigid foam products to minimize the use of plastic products and rely more on sustainable technology. There is a particular need for such products to provide increased environmental and economic advantages in that they are rigid, do not require long drying times, and dry easily with minimal shrinkage.

Disclosure of Invention

The present invention addresses a continuing need by providing foam compositions comprising renewable fibers and methods of making such compositions. The present invention addresses several factors that limit the success of known methods of manufacturing articles from conventional fiber-based formulations. All equipment used for processing the compositions of the invention are generally used commercially, for example in the food container or plastics industry. Many of the currently commercially available foams typically require the use of expensive extrusion equipment. Although the present invention may be adapted for use with extrusion equipment, the present invention does not require expensive extrusion equipment or other custom-made equipment. In addition, if a particular shape is desired, the fibrous foam of the present invention can be made with a binder that allows it to be compression molded as a post-processing step. If desired, the composition of the present invention may be dried outside the mold and then compression molded into a shape. By drying the foam outside the mold, it can be done more efficiently at ambient conditions, if desired, thereby minimizing energy costs.

In one aspect, the foam composition of the present invention comprises a fibrous component, at least one optional binder (e.g., starch and/or polyvinyl alcohol, PVA), at least one dispersant, and at least one surfactant/foaming agent, the binder being distributed substantially throughout the fibrous component to produce a fibrous matrix consisting of individual separated fibers substantially free of substantial amounts of agglomerated fibers. The surfactant has two functions: as a blowing agent, and as a dispersing agent to help disperse the fibers. Likewise, starch and PVA as binders may also act as fiber dispersants. In addition, some additives (e.g., PVA, sodium silicate) help to promote foam bubble formation during the mixing/shearing step. Some fibers and/or binders (e.g., starch) tend to inhibit the foaming action of the surfactant/foaming agent. In this case, the PVA solution helps to achieve the desired amount of foaming. The fibrous component, surfactant/foaming agent, dispersant and optional binder combine to form a foam product that resists shrinkage and remains rigid during drying. The surfactant/foaming agent is typically added to the composition of the present invention when the fiber component reaches a predetermined dryness. To provide additional shrink resistance, polylactic acid (PLA) fibers (less than about 0.1mm thick) or stiff fibers (e.g., wheat straw or PLA fibers having a thickness of about 0.25mm to about 0.75 mm) may also be used in the composition. The final foam product is a rigid foam that can provide thermal, acoustical and impact resistance, or it can be formulated with a binder (such as starch) and compressed into a finished product (e.g., board) or used as moldable foam insulation. PLA fibers may also be used in the composition in order to provide additional shrink resistance. The final biodegradable foam product is a rigid foam that can provide thermal, acoustical and impact resistance, or it can be formulated with a binder and pressed into a finished product (e.g., a board) or used as moldable foam insulation.

It is an advantage of the present invention to provide novel compositions and methods for rigid, compressible and renewable foam composites comprised of fibers, at least one dispersant, at least one binder, optional fillers, and surfactants as blowing agents.

It is another advantage of the present invention to provide a foam composite that can be commercially mass produced using equipment commonly used in the food and plastic industries to maintain low capital costs while also being adaptable to extrusion equipment if desired.

Another advantage of the present invention is to provide a new compostable foam food service product that is comparable to the convenience and cost of traditional paper products.

Another advantage of the present invention is to provide compositions that are compressible and moldable (or extrudable) into a variety of articles, including packaging materials and food containers, as well as thermal, acoustical and impact resistant materials, and that can also be dried with little or no shrinkage.

Another advantage of the present invention is to provide novel compositions that resist shrinkage and can be dried with greater efficiency, thereby using minimal water during processing.

Another advantage of the present invention is to provide a cellulosic foam composition that is rigid and stable and requires minimal removal of water during or after processing.

It is another advantage of the present invention to provide a cellulosic foam composition that is rigid and stable without the need to remove the activated water during or after processing.

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify all key or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

Drawings

This patent or application document contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the office upon request and payment of the necessary fee.

Figure 1 shows a general scheme for a method of preparing a composition as described below.

Fig. 2 shows the force-deflection curves for wet foams made from the F1 and F3 formulations as described below.

Fig. 3 shows the stress/strain curves for the inventive fibrous foam and comparative polystyrene as described below, with compression set tested up to 10%.

Fig. 4 is a photograph showing structural differences between samples made from formulations F1, F2, and F3 (left to right), as described below.

Fig. 5 is a magnified photograph showing the fine network structure characteristics of a dry foam sample made from formulation 2(F2) as described below.

Fig. 6 is a magnified photograph showing the coarse network structure characteristics of a dry foam sample made from formulation 3(F3) as described below.

Fig. 7 is a photomicrograph of the fiber network of the dry foam made from F3, described below, showing coarse fiber bundles.

Fig. 8 is a photomicrograph of the fiber network of the dry foam made from F2, described below, showing PLA fine fiber bundles scattered throughout.

Detailed Description

Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The definitions described herein may or may not be in uppercase, singular or plural form and are intended as guidelines for one of ordinary skill in the art to make and use the invention and are not intended to limit the scope of the claimed invention. The reference herein to a trade name or commercial product is merely for the purpose of providing specific information or examples and does not imply a recommendation or approval for such a product.

As used in the description of the invention and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The term "binder" refers to any water soluble component added to the composition of the present invention that results in an increase in hardness (rigidness). For example, these components may be selected from polyvinyl alcohol, starch, sodium silicate, gelatin, gums, alginates, and the like, and combinations thereof. The binder may also include a polymer solution, molten wax, or the like, which may be infiltrated into the porous fibrous matrix and then dried to remove solvent in the case of a polymer solution, or cooled to impart additional stiffness and/or moisture resistance in the case of a molten wax.

The term "biopolymer" refers to any polymer having repeating units derived, at least in part or in whole, from a biorenewable source (e.g., biobased) including through agricultural production.

The term "consisting essentially of … …" excludes additional method (or process) steps or composition components that substantially interfere with the intended activity of the method (or process) or composition and that can be readily determined by one of ordinary skill in the art (e.g., from consideration of the present specification or from consideration of the practice of the invention disclosed herein). The term may be used in place of an inclusive term, such as "comprising" or "including" to define any disclosed embodiment or combination/sub-combination thereof in a narrower sense. Moreover, the exclusive (exclusive) term "consisting of … … (constitutive)" is also to be understood as an alternative to these inclusive (exclusive) terms.

The term "container" or "package" and the like as used herein refers to any article, container (receptacle) or vessel used for storing, dispensing, transferring, packaging, protecting (e.g., impact, movement, and thermal), cushioning, dispensing, or transporting various types of products, objects, or items (e.g., food and beverage products). Specific examples of such containers include boxes, cups, jars, bottles, plates (plates), plates (dish), bowls, trays, cartons (carton), cases (case), crates (crate), cereal boxes (cereal box), frozen food boxes, milk boxes, carriers and holders (e.g., egg boxes, 6 pack holders, boxes, bags (bag), gunny bags (sack)), lids, straws, envelopes, and the like, as well as packaging materials (e.g., loose-fill packaged peanuts, corner protectors, equipment supports, insulated packaging, hot-fill shipping boxes/containers, foam coolers, and the like).

The term "effective amount" of a compound or property provided herein refers to an amount capable of performing the function of the compound or property, as that amount is expressed. As noted herein, the exact amount required will vary from process to process, depending on recognized variables such as the compounds used and the various observed internal and external conditions as understood by one of ordinary skill in the art. Thus, it is not possible to specify an exact "effective amount" although preferred ranges are provided herein. However, an appropriate effective amount can be determined by one of ordinary skill in the art using only routine experimentation

The term "fiber" refers to a complex carbohydrate of plant origin, usually classified as water-soluble or water-insoluble, usually forming threads or filaments, as a class of natural or synthetic materials, which have an axis of symmetry determined by their ratio of long to diameter (L/D). Their shape may vary, such as filamentous, cylindrical, elliptical, circular, elongated, spherical, etc., as well as combinations thereof. They may range in size from nanometers to millimeters. For example, as an additive in latex films, fibers are commonly used as a filler material to provide dimensional stability and texture variation to the final product. Natural fibers are generally derived from cellulose, hemicellulose, lignin, pectin, and proteins.

The term "matrix" as used herein generally refers to a dispersion of fibers that are typically intercalated.

The terms "optional" or "optionally" mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. For example, the phrase "optionally including a filler" means that the composition may or may not include a filler, and the description includes both compositions that include a filler and compositions that do not include a filler. Further, for example, the phrase "optionally adding a filler" means that the method (or process) may or may not involve adding a filler, and the description includes methods (or processes) that involve adding a filler and methods (or processes) that do not involve adding a filler.

The term "polylactic acid" or "PLA" refers to a biodegradable thermoplastic aliphatic polyester that is typically obtained commercially from biobased precursors (e.g., corn starch, tapioca starch, sugar cane, wheat straw, and the like, and combinations thereof). The polymer may comprise L-lactic acid monomeric units (i.e. consisting essentially of the L-lactic acid levorotatory enantiomer, which is the opposite enantiomer of the D-lactic acid enantiomer (e.g. a mirror image)) and/or D-lactic acid monomeric units (D-lactic acid monomelic units) (i.e. consisting essentially of the lactic acid dextrorotatory enantiomer, which is the opposite enantiomer of the L-lactic acid enantiomer (e.g. a mirror image)).

The term "stiff" refers to a porous fibrous matrix that resists compressive deformation. That is, excessive compressive forces can result in significant plastic deformation. Excessive deformation tends to destroy the original structure and strength. Once the original structure is destroyed, the foam generally does not rebound to the original structure and dimensions of the foam. Rigid foams typically have a modulus in MPa of about 0.1 to about 1.5 MPa.

The term "blowing agent" refers to a chemical that aids in the process of forming a wet foam and enables it to support its integrity by imparting strength to each individual cell of the foam. The concrete industry utilizes foaming agents to produce foamed concrete. Such blowing agents may also be used to make cellulosic foams. These foaming agents include hydrolyzed protein formulations as well as proprietary synthetic formulations. Other well known surfactants that can be used as blowing agents can include alkyl sulfates (e.g., Sodium Dodecyl Sulfate (SDS)), alkyl ether sulfates (e.g., sodium dodecyl ether sulfate (SLES)), and other anionic and cationic surfactants.

The term "dispersant" as used herein refers to any compound that when used in an aqueous environment, helps to separate fibers that generally tend to agglomerate into clumps or lumps. The coagulation or aggregation of the fibers creates a heterogeneous mixture and produces a weaker foam structure. Proper separation of the fibers in an aqueous environment using a dispersant allows the individual fibers to better entangle and overlap with each other and create a strong fibrous foam structure.

Figure 1 shows an example of a general scheme of how to prepare a composition comprising fibers, at least one dispersant, at least one binder and at least one surfactant/foaming agent. The dry pulp fibers are mixed in water (e.g., from about 1 ℃ to about 100 ℃, preferably from about 15 ℃ to about 90 ℃, more preferably from about 60 ℃ to about 80 ℃) to hydrate the fibers. Then removing excess water; for example, a second dewatering step is performed after the first dewatering step. The fibers are then mixed with a dispersing agent (e.g., PVA) and a binder (e.g., starch). A foaming agent (e.g., SDS) is then mixed with the fibers, dispersant, and binder. Alternatively, the foaming agent may be added in a first mixing step together with the dispersing agent and the binder, although it is preferred that the binder is mixed and dissolved prior to the addition of the foaming agent. The resulting foam can be molded into a desired shape and dried (e.g., in an oven). PVA can also help in foaming and as a binder, starch can also help in dispersing the fibers, and foaming agents can also serve as surfactants and dispersants. For example, PVA may be used as a dispersant and a binder. Alternatively, starch may be used as a dispersant and binder. One advantage of the process of the present invention is that the present invention eliminates the prior art dehydration step. The invention proceeds with dewatering but before the addition of the dispersant, binder and foaming agent. In the prior art, the prior art adds a foaming agent prior to dehydration, thus losing all the additives contained in the discarded water. The present invention first hydrates the fiber with water only and then dehydrates it before adding any additives. The present invention reduces the moisture content to the desired low level prior to the addition of the additives. Thus, in the process of the present invention, the present invention does not waste any additives by being discarded in the dehydration step.

The cellulose foams of the present invention are typically made using fiber hydration, dewatering and mixing steps, with varying degrees of hardness. Surprisingly, the dehydrated fibers used in the present invention appear to be too dry to produce a foam, but can still be made by adding a blowing agent, a small amount of water or binder, and rigorous mixing. One skilled in the art would consider the appearance of dehydrated fiber too dry to foam in the presence of a blowing agent. It is surprising and unexpected that such a small amount of water in the fiber mixture, but still produces foam upon addition of the blowing agent. In addition, the use of low moisture foams produces smaller bubbles and results in dry foams that are not only low in density but also have high compressive strength (as described in detail below). For example, wet foams are stable and can be transferred to a mold and dried in place, or can be spread into a thin sheet. Due to the low moisture content of the foam relative to prior methods, the dewatering step (which is typically required in the prior art) is minimized or eliminated, and virtually no blowing agent or binder is lost, and drying time is reduced. Existing foaming processes typically add a foaming agent to the very dilute fiber suspension. This diluted mixture foams easily, but it is too wet and requires a much greater degree of drainage or dewatering than the composition of the invention, which makes it impractical to add binders or fillers as these are usually lost in the dewatering step. By hydrating and dewatering the fibers using the method of the present invention, the fibers remain readily dispersible. The process of the present invention reduces or eliminates any loss of blowing agent or binder or filler since no subsequent dewatering step would drain water and the ingredients added to the mixture. Minimal shrinkage is also observed during the drying step, which can be done at ambient conditions or using an oven. Biodegradable cellulose foams have low density, excellent insulating properties, and may have excellent compressive strength depending on the binder used. In addition, the dry foam can be compression molded into an article.

The present invention provides novel compositions comprising a fibrous component, at least one blowing agent, at least one dispersant, and optionally at least one binder. In a preferred embodiment, the optional binder is distributed substantially throughout the fibrous component to form the matrix, and the fibrous component, dispersant and foaming agent combine to form a foam product that is dimensionally stable and resistant to shrinkage during drying. Dimensional stability in this context means that there is no shrinkage during the drying step. Excessive shrinkage can result in the foam sheet being significantly thinner in the middle than at the edges, which are generally more supportive. Excessive shrinkage can also lead to partial collapse and densification of the foam, making the final density and volume unpredictable. Dimensional stability allows, for example, a1 inch thick foam sheet to be dried to a thickness of substantially 1 inch still uniformly. If the foam is scooped into a cavity, it is desirable that the final volume of the dry foam be similar to the wet foam. If excessive shrinkage occurs during drying, an additional amount of foam may need to be added to ensure that the filled cavity remains full once the foam is dried. Typically, when combined with a blowing agent, one or more types of fibers are dispersed throughout the matrix to form a foam. Also described herein are methods of making such compositions that are commonly used to form containers and other articles.

In embodiments, the fiber component is a fiber selected from any number of complex carbohydrates of plant origin (e.g., wood, straw, rice hulls, almond hulls, or other waste products). In general, the fiber component serves to reinforce the composition of the present invention and provides mechanical integrity and additional benefits as described herein. In embodiments, the fiber component (e.g., fiber from crop waste) can be partially or fully replaced in the formulations of the present invention to produce a more sustainable product with a lower environmental footprint than conventional fiber-based products. Preferably, the lignin fibers are separated and prepared by chemically and/or mechanically separating such fibers from pulp fibers made from, for example, wood (e.g., hardwood or softwood or combinations thereof), fiber crops (e.g., sisal, hemp, flax, and the like, combinations thereof, and the like), crop waste fibers (e.g., wheat straw, onion, artichoke, other underutilized fiber sources, and the like, combinations thereof, and the like), and waste paper (wherein soluble material has been removed from the fibers). However, it should be understood that any type of fiber known in the art may be used in the present invention. The fiber component is present in the composition in an amount of from about 82 wt% to about 95 wt%, or from about 92 wt% to about 89 wt%, or from about 89 wt% to about 95 wt% of the fibers as measured in the dry foam (typically a greater amount of fibers is present in the final formulation for a foam of the present invention containing only the fiber component and surfactant and no binder). For example, formulations containing PVA as a binder may have a lower amount of fiber in the final formulation, such as from about 82% to about 89% by weight fiber in the dry foam. When a filler is present in the foam composition, a minor amount of fiber may be present, for example from about 40 wt% to about 80 wt%. Prior to drying (see, e.g., the formulations in table 1), there is typically about 40 to about 70 weight percent fiber, depending on the particular formulation.

Preferred fibers are natural fibers that provide the ability to achieve substantially uniform dispersion in the final product, more preferred are pulped plant fibers having a length of greater than about 0.5mm (e.g., 0.5mm), and most preferred are pulped plant fibers having a fiber length of greater than about 2mm (e.g., 2mm) to about 5mm (e.g., 5mm) or about 8mm (e.g., 8mm) or about 10mm (e.g., 10 mm). It should be understood that there is no need to limit the minimum fiber length, but smaller fibers generally give less strength to the final product. However, the maximum fiber length is limited. Too long fibers tend to mix poorly and it is difficult to obtain a uniform mixture of ingredients. Without being limited by theory, the upper limit of the fiber length is believed to be about 10 mm. Fibers having a length of less than about 0.5mm may also be used, but are typically used as fillers without contributing to the strength of the final foam product. One skilled in the art will observe that the optimum amount of water will vary with the particular fiber source. The operator needs to establish an optimum water content for each fiber mixture of interest. Some plant fibers absorb more water during the hydration step than other fibers, which will affect the amount of water added to achieve the optimum hydration level. In all cases, the amount of water added should be reduced until no foam is obtained. Once this point is determined for a given fiber blend, water should be added to obtain an optimal blend.

The binder acts as an agent to hold or "glue" the individual fibers together in the dry foam. The binder remains substantially uniformly distributed throughout the matrix, also helping to ensure that the fibrous component remains uniformly distributed throughout the matrix and providing increased stiffness to the final product. In embodiments, the binder may be derived from various agricultural sources and commercial or synthetic materials, and is generally composed of components such as PVA, starch, sodium silicate, gelatin, gums, alginates, and the like, and combinations thereof. For example, binders and starches from natural sources (including proteins from corn, wheat, soy), starches from commercial crops (including corn, wheat, potato, tapioca, pea, etc.), waxes from plant sources such as soy or petroleum derived chemicals, and polymer solutions (including PVA in water, PLA in solvent, shellac in ethanol, etc.) may be used as binders. The degree to which the binder affects the hardness depends on the concentration used and the fluidity of the binder in water. For example, small molecular weight binders such as sodium silicate flow readily with moisture during drying. Thus, during drying, a large portion of the adhesive may migrate to the outer surface of the foam. In contrast, high molecular weight binders (e.g., starch) are much less fluid during drying and tend to bind the fibers throughout the foam structure. The binder may also increase the flexural strength of the foam. This foam sample did not crack as easily as a foam without a binder. Some binders (e.g., shellac, wax, and PVA) not only increase stiffness and flexural strength, but also improve moisture resistance. In the compositions of the present invention, the binder is distributed throughout substantially the entire matrix and contributes to the desired level of high compressive strength of the wet foam (higher compressive strength of the wet foam means less shrinkage of the foam during the drying step, see examples). Starch is generally composed of high molecular weight and water soluble amylose and amylopectin. When granular starch is heated in water, the granules swell and absorb moisture. High molecular weight starch polymers disperse in water and increase viscosity. Adding more starch tends to increase the concentration of starch polymer dissolved in water, further increasing viscosity. It is also well known in the literature that starch is readily biodegradable compared to fibres and therefore higher levels in the composition of the invention result in a more environmentally friendly product.

In embodiments, the binder is preferably present in the compositions of the present invention in an amount of from about 1 wt% (e.g., 1 wt%) to about 50 wt% (e.g., 50 wt%), or from about 2 wt% (e.g., 2 wt%) to about 30 wt% (e.g., 30 wt%), or from about 3 wt% (e.g., 3 wt%) to about 10 wt% (e.g., 10 wt%). It will be appreciated that the amount of the particular binder solution added may vary depending on the concentration to achieve the desired amount in the final formulation.

In embodiments, the compositions of the present invention include a blowing agent. Preferably, the foaming agent is selected from anionic surfactants and cationic surfactants known in the art. Such surfactants can be developed for other industrial purposes, but have the foaming capacity required by the present invention. Nonionic surfactants also do not foam easily and are therefore not recommended. Other foaming agents, such as those typically used in concrete made from hydrolyzed proteins as well as proteins such as ovalbumin, can also produce foam. Preferred blowing agents include sodium lauryl sulfate and commercial blowing agents (e.g., CMX Foam Concentrate, Richway Industries, ltd., Janesville, IA). While various dilute solutions are known to produce foam upon addition of surfactants, it is a surprising and unexpected result that the viscous fiber compositions of the present invention can be readily foamed with the addition of a foaming agent. The action of the gas bubbles formed in the fibrous matrix effectively separates the individual fibers, producing a uniform fibrous foam that can flow without the fibrous components separating out or clumping together. Even a small amount of foaming is sufficient to help the fiber composition flow when external pressure is applied. It is desirable to obtain a wet fibrous foam consisting of a matrix of air bubbles in which the fibrous components are well dispersed or suspended. The blowing agent is added to the fiber suspension when the water to fiber ratio is from about 2:1 to about 8:1, or from about 2:1 to about 5:1, or from about 2:1 to about 3: 1. In the final formulation, the blowing agent is present in an amount of from about 1 wt% to about 10 wt%, or from about 3 wt% to about 8 wt%, or from about 5 wt% to about 7 wt%.

In embodiments, the compositions of the present invention include at least one dispersant, which may function in conjunction with a blowing agent. The dispersing agent can provide a mechanism for distributing the fiber components throughout the matrix (e.g., a bubble matrix) and combining with other components of the disclosed compositions to produce a viscous dough (dough) to form a foam and help prevent the tendency of the pulped fibers to clump and form lumps. The addition of a dispersing agent and/or a blowing agent (with or without optional physical shearing) to the composition of the present invention effectively separates the fibers into individual fibers that are uniformly distributed throughout the foam matrix. The properly dispersed fibers reinforce and strengthen the matrix. The fiber clumps are undesirable and do not provide the desired strength or reinforcement to the composition of the present invention or the products formed therefrom. As discussed further herein, the ability of the dispersing agent to adequately distribute the fibrous component throughout the matrix depends on the use of relatively small amounts of water to produce a dough with a sufficiently high viscosity for use in the method of the present invention. Viscosity is measured by methods known in the art. For example, a texture meter may be used to measure the characteristics of the force response (i.e., a way to profile viscosity) resulting from the mechanical properties (e.g., resistance), texture analysis, texture profile analysis, etc.) of a dough composition. Such mechanical properties are associated with specific organoleptic textural attributes and affect the performance of the compositions in forming articles as well as the quality and performance of these articles in various applications.

For example, a preferred force response, as measured by inserting an 3.682 inch probe into a foam composition container to a depth of about 20mm, is from about 0.005kN (about 510 grams) to about 0.02kN (about 2040 grams). It will be appreciated that the upper limit of the viscosity range will depend on the compression force of the molding equipment, and that the skilled artisan can adjust the desired viscosity range for a particular application of the composition of the present invention. Harder doughs generally better retain their shape when the molded part is demolded (i.e., removed from the mold). More preferably, the resistive force is greater than about 510 grams (e.g., 510 grams) and up to about 2500 grams (e.g., 2500 grams). Most preferably, the resistance is greater than about 600 grams (e.g., 600 grams or greater), or greater than about 2500 grams (e.g., 2500 grams), or greater than about 5000 grams (e.g., 5000 grams or greater), or greater than about 8000 grams (e.g., 8000 grams or greater), up to 10000 grams.

Examples of preferred fiber dispersing agents include PVA, gelatinized and pregelatinized starches, carboxymethylcellulose and derivatives thereof, hydroxymethylcellulose and derivatives thereof, water-soluble viscosity modifiers (including vegetable gums (e.g., such as alginates, guar gum, gum arabic, gum ghatti, gum tragacanth, gum karaya, xanthan gum, gellan gum, tara gum, glucomannan gum, locust bean gum, glucomannan gum, and the like)). Preferred dispersants include those naturally derived dispersants that provide the best balance of price and function. For example, PVA is synthetic and quite expensive, but provides strength and good oil resistance. Most preferred are starches because they are natural, low cost and biodegradable. In embodiments, the dispersant is present in the compositions of the present invention in an amount of about 0.5 wt% (e.g., 0.5 wt%) to about 10 wt% (e.g., 10 wt%), or about 0.5 wt% (e.g., 0.5 wt%) to about 5 wt% (e.g., 5 wt%).

The compositions of the present invention may be formed by various methods. One exemplary method includes dispersing the fiber pulp in water (e.g., hot water) and then capturing the fibers on a screen to remove excess water. Optionally, a binder may be added, such as a gelatinized slurry of starch or pregelatinized starch powder or other binders discussed herein. Optional fillers (e.g., calcium carbonate) and fiber dispersants (e.g., dilute solutions of PVA) can be added and then combined completely. The mixture is generally of sufficient viscosity at this stage to promote uniform dispersion of the fibrous component in the matrix of the composition. After thorough mixing, a blowing agent is added (unless the blowing agent is used as a dispersant, in which case no additional blowing agent may be needed) to initiate the foaming process of the composition of the present invention. Alternatively, the foaming agent may be pre-foamed and added to the fiber mixture. If desired, additional amounts of water may be added to facilitate the foaming process. The mixture is vigorously agitated with a paddle mixer or other similar type of mixer to effectively mix air into the composition. The blowing agent helps to form a stable foam structure during mixing. The foam composition may then be poured or spooned into a mold or laid into foam pieces. The foam may be placed in an oven or air dried to remove at least a portion of the water in the mixture. The desired dryness is less than about 10 wt% water, or less than about 8 wt% water, or less than about 5 wt% water. Conventional wet foams have an undesirable tendency to collapse during drying. Surprisingly, the subject foams are sufficiently stable to be dried in an oven while still maintaining the desired rigid and porous structure. The outer surface may also have some densification which results in the composition of the present invention forming a smooth skin-like structure. However, much of the original foam structure is retained during the drying process. The dry foam has considerable compressive strength and low density. There is generally a positive correlation between density and strength. The greater the density, the greater the compressive strength. For example, the density may range from about 0.02g/cm³To about 0.4g/cm³. Denser samples have less void space, are generally stronger, and have a binder. The compressive strength in the range of about 20% deformation may be, for exampleE.g., about 1kPa to greater than about 80 kPa. Foam densities comparable to polystyrene foam (e.g., 0.05 g/cm) can be obtained³). The density of the foam composition of the present invention can be adjusted by the particular choice of components and is about 0.02g/cm³To about 0.10g/cm³Or to about 0.4g/cm³. For some applications, very low density and good thermal insulation properties may be required. For other applications, higher density and good compressive strength may be required. For example, for thermal and acoustical insulation, a density of about 0.02g/cm is desirable³To about 0.06g/cm³. Density (g/cm)³) An example of the relationship between hardness (modulus in MPa) and 20% compressive strength (kN) is 0.062g/cm³、0.063MPa、10.50KN；0.043g/cm³、0.015MPa、2.47kN；0.039g/cm³、0.011MPa、2.12kN；0.080g/cm³、0.195MPa、35.10kN；0.052g/cm³、0.029MPa、6.02kN；0.054g/cm³0.057MPa and 11.9 kN. Cellulose fibers are hollow and are a good sound and heat insulating material. Low density foam consisting of well dispersed fibers and small pore sizes enhances thermal and acoustical insulation properties. It creates dead space (dead space) that limits the transfer of heat and sound by convection. The lower the density, the smaller the cell size and the less heat is transferred by conduction. These two combinations and the hollow character of the cellulose fibers result in excellent insulation properties.

Traditionally, blowing agents are added to very dilute fiber mixtures for making fiber foams. Typically, about 1% to about 5% of the fibers are mixed with the blowing agent. Since the foam produced is very dilute, a large amount of dewatering is required. The excess water is drained quickly initially but slowly afterwards. During the process of draining such large quantities of water, the fiber volume is continuously reduced as the water is drained. Eventually, the water stops draining and the fiber must be dried in an oven. By this method, most of the soluble components (e.g., blowing agent) are simply drained and discarded along with excess water, unless special efforts are made to reuse/recover the blowing agent. The system is also impractical for adding water soluble binders because they are also drained with excess water and discarded unless special efforts are made to reuse/recover the components. For example, the concept of the present invention is to pre-hydrate the fibers in excess water. The fiber and hot water were placed in a large blender and mixed to separate the fiber and completely hydrate it. Once the fibers are hydrated, the mixture can be mixed again to ensure good fiber separation. Next, the water is drained on a screen and the fibers are squeezed to remove more water until the desired fiber to water ratio (e.g., about 1 to about 2) is achieved. It will be appreciated that, for example, if 25g of dry pulp fibers were simply mixed with 50g of water, the fibers would not be sufficiently hydrated and dispersed. The pulp fibers are in the form of dry sheets, which look like thick cardboard. When they are dried in this manner, there are a large number of hydrogen bonds between the fibers. The hydration step loosens the fibers and breaks the hydrogen bonds. If the fiber is sufficiently dried, hydrogen bonding can occur again and will not produce the desired results. By pre-hydrating the fibers, the fibers become loose and easily separated again. The dewatered or pressed fibrous material is a solid mass without free water. One skilled in the art would expect that a substantial amount of liquid would be required to foam the fiber mixture after the blowing agent is added. Surprisingly, mixing the fiber/blowing agent mixture results in the formation of very small bubbles. After continuous rapid mixing, the foaming action proceeds to the extent that the volume of the mixture increases due to the formation of more bubbles. An advantage of minimizing the added water is that the resulting foam shrinks very little when dried. In addition, any binder or filler added to the mixture remains in the dried foam. In other words, the binder is less likely to migrate with water during the drying step due to the low initial moisture content. This is not possible when excess water is used to make the foam, followed by a dehydration step as is commonly done in the art. The traditional approach is to add all ingredients to an excess of water and then dewater, which results in the waste of other ingredients already added to the water. When the foam is made from fibers and blowing agent only, the fiber to water ratio is as low as about 1:2 to about 1: 3. However, when a binder is added, more water may be required, as the binder may absorb some water or reduce foaming. The skilled person must optimize each component.

The specific dryness will vary from formulation to formulation. Therefore, it is important to determine the optimum dryness of each composition. For formulations containing only the fiber component, water, dispersant and blowing agent, the fiber is first hydrated in a blender with water, which is heated to a relatively high temperature (e.g., to greater than about 60 ℃, but not exceeding the temperature of boiling water (100 ℃). After mixing for 1 minute, the fiber is allowed to hydrate for about 15-20 minutes, then mixed again for about 1 minute, and then the fiber is collected on a screen (e.g., 40 mesh). The fibers were collected and compressed to squeeze out excess moisture. It is advantageous to minimize the water to fiber ratio to keep the drying time and drying energy as low as possible. It is more preferred to maintain the water to fiber ratio less than about 5.0. It is more preferred to maintain the water to fiber ratio less than about 4.0. Most preferably, the water to fiber ratio is maintained less than about 3.0 prior to addition of the blowing agent. The most preferred water to component ratio must be determined by trial and error when adding a binder (e.g., starch) or other fiber to the composition. By minimizing the water content to the point where foaming occurs, shrinkage during drying is minimized, foam hardness is increased, and drying time is minimized.

In embodiments, the compositions of the present invention can be used to form articles in an economical and commercially efficient manner by allowing articles to be produced with short cycle times as compared to conventional compositions and methods. For example, in conventional methods, drying the molded article in the mold for a long period of time (e.g., about 60 to about 200 seconds) places an unacceptable limit on productivity and increases costs. For example, when a binder (e.g., starch) is used in the composition of the present invention, it is compressed into a dry foam (typically having about 8% moisture at that point) outside the mold, and then the dry foam is compression molded in about 5 seconds. In addition, the present invention can employ existing production equipment (e.g., thermoforming machinery, hydraulic presses) which increases its cost effectiveness and commercial desirability, and can also employ custom-made equipment to produce a particular article.

The final products (e.g., food board, packaging material, thermal insulation products, acoustical insulation products, etc.) formed from the compositions of the present invention are generally similar in appearance to corresponding conventional products. Some potential applications may be as a replacement for rigid packaging foams of polystyrene as packaging equipment. The loose pack can be made by cutting a block of foam to a size similar to that of a packed peanut. Since the foam is compressible, it may also be compression molded to form a foam part, or it may be compressed into a solid part, such as a food pan or bowl. For sheet materials, the foam may be deposited on a film sheet of a degradable polymer (e.g., polylactic acid, biodegradable polyester, or natural biopolymer (e.g., Polyhydroxyalkanoate (PHA)), for example, once the foam is dried on the film sheet in an oven, the foam may be compressed into a sheet with the film side on top.

Fibrous composites may also be prepared using the compositions of the present invention by mixing a biopolymer comprising starch and polylactic acid (PLA) with agricultural fibers as further described herein. The fiber source preferably includes rice hulls, straw, almond hulls, and the like. The fibrous composite material can be extruded, for example, by a twin screw extruder using rod dies of various diameters (e.g., diameters from about 2mm to about 20mm depending on the size of the extrusion apparatus — the larger the die, the less likely the fibers will collect and plug the die). The extrudate is pelletized using, for example, a50 ton injection molding machine and then processed into products (e.g., the pellets can be injection molded into various articles or extruded into sheets and thermoformed into various articles, just like conventional plastics). The strength and mechanical properties of these articles will be comparable to or exceed those of commercially available tableware made from pure PLA and other materials. Such fiber-reinforced composites of the present invention can be used directly to produce commercial products.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the errors found in their respective measurements. The following examples are intended only to further illustrate the invention and are not intended to limit the scope of the invention as defined by the claims in any way.

Example 1

This example provides an illustration of the preparation of the compositions of the present invention using a variety of starting materials. Unbleached kraft pulp was purchased from PortTownsend Paper Corp (townsend, washington). Polylactic acid (PLA) fibers were obtained from minifibbers, Inc (johnson city, tennessee, usa) and had a fiber length of 6mm and a fiber diameter of 13 μm (1.5 denier). Pregelatinized, cold-water soluble potato starch (Emjel E70) was purchased fromGmbH (illiichiem, germany) and is used as a binder/dispersant. Calcium carbonate was purchased from Diamond K Gypsum (richfield, utah, usa) and used as a low cost filler. Commercially available blowing agents (Foamcell a100) were purchased from Goodson and Associates (malling, colorado); alternatively, Richway CreteFoam may also be used^TMCMX concentrated foam. Polyvinyl alcohol (PVA, Celvol)^TMPVA504) was purchased from Celanese Chemicals (dallas, texas) and used as a dispersant/binder. Polystyrene foam board insulation (insulating foam) is a common item, purchased from local hardware stores.

Samples of the composition of the present invention were prepared for testing by first placing 40 grams of cellulose fibers in hot water (about 80 ℃) in a waring blender and mixing for about 1 minute. The mixture was allowed to stand for about 15 minutes to allow the fiber portion to fully hydrate. After standing for about 15 minutes, the mixture was mixed again for about 30 seconds to ensure complete dispersion of the fibers in the water. Excess water is removed (e.g., the contents of the blender are then poured onto a screen (120 mesh) to drain the excess water, and the fibers are carefully agglomerated on the screen into a mass and manually compressed to remove the excess water). The final weight of the hydrated fiber mass was 300 grams (40 grams of fiber and 260 grams of water). The hydrated fiber mass was placed in a Hobart planetary mixer (model N50) and mixed at its mostStirring was carried out at low speed (about 60 rpm). 100 grams of 5% (w/w) PVA or 5 grams of solid PVA were added to the hydrated fiber mass and then mixed for about 2 minutes. The PVA solution can be used as a fiber dispersing agent, although it can have various effects (see, e.g., H).(iii) the reliability of foam coating on application of the thin liquid files, (2010)). During mixing, pregelatinized potato starch powder (15g) was added to the sample as a binder. Since starch tends to cake if added all at once, it is often necessary to slowly spill the powder into the mixture to avoid this problem. In addition to acting as a binder, starch helps to disperse the fibers by adhering and pulling apart the fibers when the paddle kneads the cohesive dough. After all the starch was added, the mixture was thoroughly mixed for a few minutes, with periodic stops to scrape the stirred tank.

Next, 4 grams of blowing agent (Foamcell a100) was added to the mixing tank. The contents of the mixing tank were mixed vigorously for about 15 minutes. During this mixing stage, air is entrained into the viscous dough component by the mixing action. Initially, it appeared that more water or blowing agent was required to produce the desired foam product. However, once the blowing agent was uniformly dispersed throughout the sample, foam was surprisingly generated despite the thick, viscous mixture. Upon foaming, the sample volume expanded to about 8 to 12 times the original volume. The mixing was stopped and the foam was scooped onto a paper lined aluminum plate. Two shims (spacers) were placed on the edges of the panel and a flat bar was used to spread the foam and shims together evenly. Foam pieces having a uniform thickness (approximately 1 inch by 8 inches by 12 inches) were formed and then placed in a forced-air oven (forced-air oven) maintained at 80 ℃. The foam was dried overnight before being removed from the oven.

Example 2

This example illustrates the physical and mechanical properties of the compositions of the invention in both hydrated and non-hydrated forms. Hydrated foam samples were prepared as described in example 1 and scooped into the test equipment. The compressive strength and modulus of the samples were determined by pressing a 93mm piston into a100 mm wet foam cylinder about 4 inches deep. The force required to press the piston to a depth of 40mm at a rate of 2.54mm/min was recorded.

Dry (i.e., non-hydrated) foam samples were prepared by the following method: a cylindrical mold (165mm x 80mm) was first filled with hydrated foam prepared as described in previous example 1. The foam cylinders were then dried at 80 ℃ overnight. Foam density is determined by weight and volume measurements. As previously described, shrinkage during Drying was recorded (O.Timofeev et al, Drying of foam-formed from virgin pin fibers, Drying technology,34(10):1210-1218 (2016)). For mechanical testing, the dry foam samples were removed from the molds and Ca (NO) was used in an incubator at 54% relative humidity₃)₂Pretreatment with Saturated salt solution for 48 hours (L.B. Rockland, protected salts for static control of relative humidity between 5 ℃ and 40 ℃, Analytical Chemistry,32(10): 1375-. The pretreatment was performed at standard levels of relative humidity, as the mechanical properties of the samples may vary with the humidity level of the foam. The foam samples were compression tested according to ASTM D1621 using a deformation of 10% and a deformation rate of 2.54 mm/min. All mechanical tests were carried out using a universal tester (model Instron 4500, campton, ma).

Three different formulations were made into the compositions of the present invention as shown in table 1. Three samples of each formulation were made for subsequent testing.

TABLE 1

The PLA fibers of the wet foam (F1) were stiffer than the wet foam (F3) made from unbleached cellulose fibers alone. The force deflection curve shows that the compressive strength of the PLA-containing foam (F1) is approximately twice that of the F3 sample made from cellulose fibers only (fig. 2). Without being limited by theory, the results that dry F1 foam also has a higher compressive strength than the dry F3 foam sample may indicate a correlation between the compressive strength of the wet foam and the compressive strength of the corresponding foam after drying. The hardness of the wet foam is important in order to form a dimensionally stable foam material that does not shrink upon drying. Although all samples showed little shrinkage, the foam sample made from F3 was particularly robust and surprisingly demonstrated little or no shrinkage during drying (data not included). The wet foam sample, which was prepared by dispersing the fibers in excess water and mixing them with SDS using conventional methods, can be dewatered in a mold. The sample will typically shrink more than 100% of the original volume. Even though the final density was relatively low, the shrinkage of the test foam samples was negligible. Its density is not as low as some conventionally prepared foams, but it is very low compared to conventionally prepared foams, with negligible shrinkage and surprising hardness.

Mechanical and physical test results of the dry foam indicate that the foam can effectively replace polystyrene foam because the foam of the present invention has similar properties. Surprisingly and unexpectedly, the samples of the present invention tested had similar thermal insulation properties to polystyrene, since the density of the samples was higher than that of polystyrene. It is well known that thermal conductivity generally increases with density, and therefore surprisingly, the more dense foams of the present invention have similar thermal conductivity values. Table 2 shows some physical and mechanical properties of the fiber foam samples compared to polystyrene foam. The samples were tested under compression up to 10% deformation. By way of comparison, the R-value of the cellulose batt prepared by the conventional foaming method was 4.09. Free of CaCO₃Has a density of about 0.036g/cm³. The density of the polystyrene samples tested was less than half that of the inventive composition. However, the thermal insulation performance of the fibrous foam is only slightly lower based on the measured R-value. The compressive stress/strain curve for the sample tested to 10% deformation indicates that the modulus and peak strength of the polystyrene sample are greater than the fiber foam sample (fig. 3). This finding shows that the test results for the foam composition of the present invention surprisingly have comparable thermal insulation properties, but lower strength and hardness compared to polystyrene. It was observed that the density of the polystyrene foam purchased was much lower, but its modulus (hardness) and resistanceThe compressive strength is greater than the fibrous foam of the present invention. Nonetheless, the R-value of formulation 1 is surprisingly similar to that of the commercial comparative polystyrene sample.

Table 2: comparison with polystyrene foam

Example 3

This example shows the physical appearance and insulation properties of the composition of the invention. Based on the difference in formation, the dry foam sample had a unique appearance. Figure 4 photographically illustrates the structural differences between foam samples made from formulations F1, F2, and F3 (left to right). Both foam samples with PLA fibers had a lighter colored appearance than the foam without PLA fibers. Formulation F2 was the lightest in color and due to the addition of mineral fillers (CaCO) in this example₃) And the density is the greatest. CaCO₃Are common mineral fillers in plastics and are white in color. A close-up view of F2 shows a very fine fiber structure (fig. 5). From a distance, the sample appears almost solid, but a close-up view shows a fine network of individual fibers. The structure of the foam made from F1 was similar to that of the F2 sample shown in fig. 5. In contrast to the formation with PLA fibers, the dry foam made from formulation 3(F3) had a porous fiber structure. A close-up view of the dry foam shows a very distinct fiber network (fig. 6). Surprisingly, the incorporation of PLA fibers into the compositions of the present invention helps to maintain separation between the cellulose fibers. As a result, surprisingly, the inventive foam is a more effective insulator and has a higher R value than would be expected in the absence of PLA (compare F1 and F3 above, where the R value of F1 is similar to commercially available polystyrene with PLA added to the inventive composition).

Microscopy of samples of the invention was performed using transmitted light in a Leica mz16F microscope (Leica Biosystems, inc., Buffalo Grove, italy) equipped with a digital camera, Retiga 2000R FAST color camera (Qimaging, Surrey, BC, canada). Foam samples containing cellulose fibers and PLA fibers were cut into 2mm slices and mounted on standard microscope slides. The exposure time was adjusted to 300 milliseconds. The settings of the zoom magnification converter are at positions 1 and 4. The scale is added after scanning using the scale at the same setting. The micrograph of F3 shows that the coarse fibrous structure seen in fig. 6 is a bundle of some fibers that are bonded together during the foaming process or during the drying step (fig. 7). Without being limited by theory, the fibers are likely to form bundles due to hydrogen bonding with adjacent fibers. The formation of the fiber bundles may occur during the foaming step or drying process while the fibers still move somewhat throughout the structure. Fig. 8 is a photomicrograph demonstrating the surprising and unexpected low porosity of foam samples (F1 and F2) containing PLA fibers. The voids between the fibers are much smaller, and the fiber network is generally composed of fewer fiber bundles, as compared to the sample without PLA fibers (i.e., F3). PLA fibres (fine and long fibres evident in figure 8) appear to be inserted or interspersed between the fibres of the unbleached kraft pulp, preventing them from bonding to each other and forming such distinct bundles as in the F3 sample. This surprising and unexpected result helps to increase the surface area of the foam containing PLA fibers and reduce the pore size of the foam.

By adding a portion of PLA fibers to the cellulose fibers, the cellulose fibers are surprisingly prevented from gathering into thick strands or yarns. One skilled in the art would expect the cellulose fibers to be more bonded to other cellulose fibers and the PLA fibers to be bonded to other PLA fibers than the results observed. Without being bound by theory, it is believed that the PLA fibers keep the cellulose fibers separated, which allows the foam to have smaller pore sizes and improved insulation properties (see R-values in table 2). Reducing pore size without increasing density is also believed to improve thermal and acoustic insulation.

Example 4

This example illustrates the method of forming the composition of the present invention into a sheet as a potential commercial embodiment. Bleached softwood and hardwood pulp fiber samples were obtained from Georgia-Pacific (atlanta, Georgia, usa). 20 grams of softwood and 10 grams of hardwood pulp fibers were slit into strips less than 2 inches wide and placed in a waring tank containing 1 liter of hot water (80℃.)In a stirrer. After 10 minutes of soaking, the fibers were mixed for 2 minutes to disperse them uniformly in water. The contents of the stirrer were poured onto an 80 mesh screen and rinsed with water. The fibers were collected by hand and squeezed to a final weight of 150 grams (consisting of approximately 30 grams total fiber and 120 grams water). 100 grams of PVA solution (5%) was added to the mixing tank of the Hobard mixer. After the addition of the fiber, the contents were mixed for about two minutes while pregelatinized potato starch (about 12g) was carefully added to the fiber mixture in this mixing step. Starch was slowly sprinkled into the mixture to avoid clumping. The mixture was stirred at a second speed (about 120rpm) for 10 minutes. Next, 40g of CaCO₃Mix into the mixture until completely dispersed (about 5 minutes). Once the mixture was uniformly mixed and the fibers were well dispersed, 4g of foamcell 100 surfactant was added and mixed at the second speed setting for about 15 minutes. Once the surfactant is dispersed in the fiber mixture, foam begins to form. With additional mixing, the volume of the foam increased from about 600% to about 900% to the point of filling the mixing tank.

Will be 30cm²The aluminum plate was covered with a PLA film that was held in place by taping at each corner. The wet foam was spooned out of the hobart mixing tank and evenly spread onto the PLA film to a thickness of 2 cm. The foam was placed in an oven maintained at 80 ℃ until it was completely dried (i.e., after an additional 20 minutes of residence in the oven, dried until the weight did not drop — typically about 3 hours, but the total time was dependent on the sample thickness). The PLA film serves two purposes. Firstly, to prevent the foam from sticking to the aluminium plate and, secondly, to provide a moisture barrier to the finished product. PLA is a biodegradable polymer that is an ideal moisture barrier; however, PLA films generally do not adhere well to starch/fiber substrates. Surprisingly, by drying the foam on the PLA film, it is possible to form a strong bond, which is achieved by drying when placed on the PLA film, which is difficult to achieve in any other way. PLA prevents the wet foam mixture from adhering to the aluminum plate to which it is attached. Once dried, the PLA film adhered well to the foam, and at the same time, allowed the foam to be removed from the aluminum plateIt becomes very simple. After removal from the aluminum plate, the foam was turned over with the film facing upward. The foam was then placed in a slab mold and compressed at 160 ℃ for 10 seconds. The mold was opened and the compressed molded panel was removed to expose a molded panel made of the starch/fiber composite of the present invention with an additional polylactic acid film moisture/grease barrier. The temperature of the mold is such that the PLA does not melt. If the mold temperature is too high, the PLA film will melt (typically the melting temperature of PLA is about 180 ℃ C.) and stick to the mold. Due to the low moisture content of the mold, it is expected that the starch will not deform sufficiently with moisture. Surprisingly, the dry foam readily formed an attractive finished product covered with a PLA moisture barrier. One skilled in the art would typically expect the foam to break and the starch to flake off like a powder. However, it was surprisingly observed that under sufficient compression force, the starch/fibre component was compressed to form an attractive surface with good strength. Such a final product requires very little processing (e.g., trimming excess material around the edges) before the product is ready for sale.

Table 3 shows mechanical testing comparisons of panels formed using the compositions of the present invention with commercial products.

Table 3: comparison of the bending Performance of the invention with molded fiber sheets

Example 5

This example illustrates the structural integrity and thermal insulation properties of the composition of the present invention. A wet foam of formulation F1 was prepared as previously described. The wet foam was scooped into the back cavity of a wine bottle container (shipper) using a spatula. Once the cavity was completely filled, the back-filled container was placed in an oven and dried overnight at 80 ℃. Once the foam is dry, the container is reassembled and tested to determine if it functions as a wine bottle container. The key criteria is to maintain structural integrity, as determined by actual field testing, which relates to whether the foam-filled container retains its shape and adequately protects the wine bottle from damage. The results demonstrate that the foams of the present invention are surprisingly able to adequately insulate and provide protection to the package contents. The foam has surprisingly succeeded in insulating wine bottles (see R-value in table 2) so that the temperature of the wine bottles is kept below a critical temperature during transportation to avoid the formation of undesired flavours in the wine.

Example 6

This example illustrates the use of native starch as a filler in the composition of the invention. A new formulation was prepared which provided fiber samples with very small pore size and very good fiber dispersion. The samples were prepared by the following steps: 20g of unbleached pulp fibers (Olympic-16) and 5g of PLA fibers were added to an industrial mixer. Water (1L) was boiled and poured into the stirrer. The fibers were mixed at low speed for 2 minutes and then hydrated for 10 minutes. The inner surface of the stirrer was rinsed with approximately 100 grams of water and the contents were again stirred at low speed for 1 minute. The contents were poured onto an 80 mesh screen and the stirrer was thoroughly rinsed of any residual fiber. The fibers were then collected by hand and squeezed to remove excess water. The final weight of the fiber mixture was 75 grams, with 50 grams being water and 25 grams being fiber. The fiber mixture was placed in a mixing tank (hobart, model N50) and for different samples 50 grams of 5% PVA and starch powder were added as shown in table 4. The fibers were mixed for 2 minutes to evenly distribute the PVA solution and starch granules. Blowing agent (2.5g, CMX blowing agent, Richway Industries) was added to the mixture and mixed at speed # 2. The blowing agent/PVA mixture effectively disperses the fibers without using any starch as a viscosity modifier. Due to the very low moisture content, it was surprisingly seen that the mixture started to foam. The sample was mixed for about 10-15 minutes. Until a small cell foam is formed.

Table 4: formulation for low moisture foam samples

Placing the foam on a sheet covered with a polyester film (e.g. biaxially oriented polyethylene terephthalate or) And finally, putting two pieces of wet tissues on the tray. The foam was formed into a sheet of uniform thickness, approximately 20cm by 15cm, using approximately 2.5cm shims. After smoothing the top surface, the foam was covered with dry paper towels and cardboard. The entire assembly is picked up and turned over so that the dry tissue and cardboard are at the bottom. Removing the tray,A sheet and a wet wipe to expose the foamed surface that previously constituted the bottom surface. The new top surface was smoothed with a spatula. The pad was removed and the final foam was carried on a paper towel/cardboard support and placed in an oven set at 80 ℃. The foam was dried for 30 minutes until a skin was formed on the surface of the foam. The foam was turned over and the moisture saturated paper towel/board was carefully removed from the foam. The bare foam was returned to the oven to complete the drying step.

The addition of native starch surprisingly increases the density and compressive strength of the foam composition of the present invention.

Example 7

This example shows additional embodiments of the compositions of the present invention as shown in table 5. After mixing the fibers in 1L of water and allowing to stand for about 10 minutes, the fibers were collected on a screen and as much water as possible was wrung out by hand. The resulting fiber balls were dried to the point where excess water could not be removed by hand. After the addition of 50g of PVA and SDS foaming agent, the mixture was mixed in a Hobart mixer for 3 minutes. The mixture produced a good foam which was dried in an oven at about 80 ℃ for about 3 hours. The foam was cut into square samples for determination of bulk density. The foam has a good structure and very fine pore size and low density. It does not have much compressive strength, but this formulation may represent the lightest, softest cushioning foam. Such formulations are relatively inexpensive and can be used to penetrate molten wax or PLA solutions to improve moisture resistance or to increase strength.

TABLE 5

The sample was made only of unbleached wood fibers. It was previously observed that starch helps prevent fibers from forming into yarns. Without intending to be bound by theory, it is theorized that the starch may bind to the fibers and help them remain dispersed. Thus, unbleached fibers were first hydrated in hot water for 15 minutes and mixed for 2 minutes, left to stand for 10 minutes, and then mixed for a second 3 minutes (15 minutes pretreatment). Next, the fibers were washed on the screen with cold tap water. Excess water from the fibers was squeezed out and returned to the mixer with 1L of cold tap water. Waxy corn starch (25 grams) was added to the mixer and all contents were mixed at high speed for 3 minutes. The fibers were collected on a screen. Excess water was squeezed out of the fiber pellets. The final weight was 100 grams. The fibers appeared to have dispersed well and, to some surprise, no more water could be wrung out of the fiber balls. The fiber and 50 grams of PVA were mixed at medium speed for 1 minute, and then 2.5 grams of SDS was added while mixing at medium speed. The fibers appear to be well dispersed.

While this invention may be embodied in many different forms, there are described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. All patents, patent applications, scientific articles, and any other referenced materials (including any materials cited in these referenced materials) referred to herein are incorporated by reference in their entirety. Furthermore, the invention includes any possible combination of some or all of the various embodiments and features described herein and/or incorporated herein. Furthermore, the present invention includes any possible combination that also specifically excludes any one or some of the various embodiments and features described and/or incorporated herein.

The amounts, percentages, and ranges disclosed herein are not meant to be limiting, and increments between the recited amounts, percentages, and ranges are specifically contemplated as part of the present invention. All ranges and parameters disclosed herein are to be understood to encompass any and all subranges subsumed therein, as well as each number between the endpoints. For example, a stated range of "1 to 10" should be considered to include any and all subranges between (including 1 and 10) the minimum value of 1 and the maximum value of 10, including all integer and decimal values; that is, starting with a minimum value of 1 or more (e.g., 1 to 6.1), ending with a maximum value of 10 or less (e.g., 2.3 to 9.4, 3 to 8, 4 to 7), and finally to all subranges subsumed within each number 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 of the range.

Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as (molecular weight), reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated otherwise, the numerical properties set forth in the following specification and claims are approximations that may vary depending upon the desired properties sought to be obtained in the embodiments of the present invention. As used herein, the term "about" refers to an amount, level, value, or quantity that varies by up to 10% from a reference amount, level, value, or quantity.

All references cited herein, including U.S. patents and U.S. patent application publications, are incorporated by reference in their entirety.

Therefore, in view of the above, the following is (partly) described:

a composition comprising (or consisting essentially of) at least one fibrous component, at least one blowing agent, at least one dispersant, and optionally at least one binder, wherein the fibrous component forms a viscous mixture that upon addition of the blowing agent converts to a foamed product once the viscous mixture reaches a predetermined dryness, wherein the foamed product resists shrinkage and remains rigid during drying.

A method of preparing a foam composition, the method comprising (or consisting essentially of) mixing at least one fiber component in water to produce hydrated fibers; excess water is removed and the fibers are mixed with at least one dispersant and optionally at least one binder, followed by the incorporation of at least one blowing agent to produce a foam composition.

The above method comprises (or consists essentially of) mixing at least one fiber component in water to produce a hydrated fiber; excess water is removed and the fibers are mixed with at least one dispersant and at least one binder, followed by the incorporation of at least one blowing agent to produce a foam composition.

An article made from the above composition.

An article made from the above composition, wherein the article is compression molded.

A composition comprising (or consisting essentially of) at least one fibrous component, at least one blowing agent, at least one dispersant, and optionally at least one binder, wherein the fibrous component forms a viscous mixture that upon addition of the blowing agent converts to a foamed product once the viscous mixture reaches a predetermined dryness, wherein the foamed product resists shrinkage and remains rigid during drying; wherein the composition is produced by a process comprising (or consisting essentially of) mixing at least one fiber component in water to produce hydrated fibers; excess water is removed and the fibers are mixed with at least one dispersant and optionally at least one binder, followed by the incorporation of at least one blowing agent to produce a foam composition.

The composition as described above, wherein the composition comprises (or consists essentially of) at least one fibrous component, at least one foaming agent, at least one dispersing agent, and at least one binder, wherein the fibrous component forms a viscous mixture that upon addition of the foaming agent converts to a foamed product once the viscous mixture reaches a predetermined dryness, wherein the foamed product resists shrinkage and remains rigid during drying; wherein the composition is produced by a process comprising (or consisting essentially of) mixing at least one fiber component in water to produce hydrated fibers; excess water is removed and the fibers are mixed with at least one dispersant and at least one binder, followed by the incorporation of at least one blowing agent to produce a foam composition.

A foam composition comprising a fibrous component, at least one blowing agent, at least one dispersant and optionally at least one binder, wherein the components form a viscous mixture that is converted into a foamed product by mechanical mixing in of the blowing agent. The foam may be dried to form a solid, and both viscous and solid forms of the foam are claimed herein.

A method of making the above-described foam composition, the method comprising mixing fibers in water to produce hydrated fibers, removing excess water from the fibers and mixing the fibers with at least one dispersant to produce dispersed fibers and mixing the dispersed fibers with at least one binder to produce a viscous fiber suspension, and mixing the viscous fiber suspension with at least one blowing agent to entrain air or other gas to produce the foam composition.

The term "consisting essentially of … …" excludes additional method (or process) steps or composition components that substantially interfere with the intended activity of the method (or process) or composition and can be readily determined by one of ordinary skill in the art (e.g., from consideration of the present specification or practice of the invention disclosed herein).

The invention illustratively disclosed herein suitably may be practiced in the absence of any element(s) (e.g., method (or process) step or composition component) not specifically disclosed herein. Thus, the specification includes disclosure by silencing ("Negative Limitations In Patent classes," AIPLA Quaterly Journal, Tom Brody,41(1):46-47 (2013): … … written support for Negative Limitations can also be disputed by the absence of elements excluded In the specification, referred to as disclosure by silencing … …. the silencing In the specification can be used to establish written descriptive support for Negative Limitations. for example, In Ex part Lin [ No.2009 and 0486, at 2,6(B.P.A.I.May 7,2009) ], Negative Limitations are added by modifying … ….

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims. Although any methods (or processes) and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods (or processes) and materials are described herein. Those skilled in the art will recognize other equivalents to the specific embodiments described herein which equivalents are intended to be encompassed by the claims appended hereto.