Water-based coatings made from polyhydroxyalkanoate (PHA) cakes

Abstract

A biodegradable aqueous mixture for coating a substrate is disclosed that includes about 35 to about 75 weight percent water and about 25 to about 65 weight percent solids. The solids, in turn, are comprised of about 40 to about 99 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids. Further, the polyhydroxyalkanoate is in the form of polyhydroxyalkanoate particles having a moisture content of about 1 weight percent or greater prior to mixing with water and a Dv(90) particle size of about 10 microns or less, as determined using ISO 8130-13:2019.

Description

[Technical field]

[0001] The present invention relates to the field of polyhydroxyalkanoates (PHA) production. More specifically, the present invention relates to the production of a novel form of PHA (referred to herein as PHA cake) and to coatings comprising this PHA cake. [Background technology]

[0002] Polyhydroxyalkanoates (PHAs) are typically produced by fermentation of bacterial or other microbial biomass in a bioreactor. First, the PHA is synthesized by and accumulates in the microbial cells. Then, after enrichment in the biomass, a multi-step process is performed to lyse the bacteria and separate the PHA from the cell debris. Finally, the biomass is dried, such as in a desiccator, and processed into a dry powder.

[0003] Dry powders can be stored and shipped, but must be rewetted before use in suspension, emulsion, dispersion, or colloidal form. Rewetting typically requires sonication, ultrasonication, low or high shear, and other processes to break down the dry particles to reduce particle size and allow for sufficient wetting of the particles by the surfactant. These processes used to rewet the material require significant time and energy and can result in significant foaming. As with any powder, dry PHAs present hazards such as explosion and inhalation. Furthermore, subsequent hydration or other solvation of the dry powder can require increased levels of additives such as dispersants and wetting agents (surfactants) to disperse and wet the particles. These additive levels tend to reduce the regulatory approval rate, biodegradability, and compostability of the material. The need for dryers to create PHA powders, as well as increased energy and water consumption as a result of adding water to the rewetting process, reduces the life cycle assessment of PHAs processed into powders. Overall, this makes PHA powder materials less sustainable.

[0004] Thus, there is a need for a method of producing PHAs that tends to at least partially reduce problems such as those introduced above.

[0005] It would also be desirable to provide a biodegradable aqueous mixture so produced that contains the PHA produced for coating a substrate. Summary of the Invention

[0006] The above needs and others are met by a method of forming polyhydroxyalkanoates (PHAs) that eliminates the heat drying process, the need for rewetting, the increased use of surfactants for dispersion, the increased energy utilization for high shear dispersion / sonication, and significant particle agglomeration that increases particle size compared to that obtained after dissolution. The resulting PHA is now referred to as PHA cake. The term "cake" is new in this disclosure and has not been used before in the PHA processing industry to describe an end-use material with the above characteristics.

[0007] The PHA cake made according to the methods described herein can be either water-based or solvent-based and is well suited for formulation of dispersions, colloids, suspensions, coatings, and similar materials. Moreover, this material is well suited for direct use in processes that utilize organic solvent and inorganic solvent systems. Examples of formulations made using this cake material include formulations such as barrier coatings and surface coatings. Additional examples of the use of this material include inclusion or embedding of electrolytes or materials in or on paper products, dispersions, colloids, emulsions, films, and heat seals. The PHA product is a dispersion of PHA in a liquid such as water or ethanol, but acts like an emulsion.

[0008] PHA is created using steps similar to those of conventional biomass processes, except that after dissolution and protein extraction, the PHA is washed alternately with organic and inorganic solvents (such as alcohol and water) in an alternating fashion, with pressurization, final filtration, cross-flow filtration, decanting, or a combination of two of these, between the washing steps. Air or nitrogen sparging, preferably at room temperature, is also performed to obtain a PHA cake with a liquid content of about 5% by weight or more, and in some embodiments, a PHA cake with a PHA content of about 60(+ / -10)% by weight and a liquid content of 40(+ / -10)% by weight.

[0009] As a result, the final PHA cake product can be used in a variety of different ways, such as by adding it to a mixer where water, surfactants, preservatives, rheology modifiers, thickeners, wetting agents, defoamers, biocides, weighting agents, binders, and dispersing agents are added, etc. These products can then be used in a variety of different ways, as described elsewhere herein.

[0010] Without undergoing a heat drying process that increases the temperature, the PHA cake retains reduced PHA particle size compared to standard PHA products that are heat dried to a solid. This particle size reduction further allows for better wetting of the PHA particles, less time / energy required to disperse the particles, less use of additives (i.e., surfactants) to prevent flocculation and particle agglomeration, and ultimately improves the processability, performance, and sustainability of the PHA material and the resulting material produced during application of the PHA cake in commercial processes. The smaller particles also improve the film-forming properties of the PHA particles as they reach their melting temperature and begin to flow onto the substrate to which they are applied.

[0011] The PHA cake is more suitable for the development of aqueous PHA (dispersion, emulsion, colloid, suspension, coating) formulations. Keeping the PHA wet reduces particle aggregation and flocculation, resulting in smaller particles that are easier to wet, disperse, and otherwise form aqueous formulations. This approach keeps the particle size in the PHA cake below about 15 microns in diameter, with about 90% of the particles being less than 8 microns in size. Additionally, keeping the PHA in cake form without heat drying reduces the cost of production. PHA materials formed using the cake offer lower minimum film formation temperatures, lower dewatering rates, improved rheological profiles, and improved barrier performance compared to those made using PHA that has been dried to a powder state.

[0012] PHA cake can be used in a commercial context to develop water-based (or any solvent-based) coating materials. Coating refers to any dispersion, solution, emulsion, colloid, or suspension that contains PHA. The PHA cake itself can be sold to customers for future formulation, or it can be formulated after production and before sale to customers. Some end users of PHA cake include chemical manufacturers, paper and substrate manufacturers, molded fiber packaging companies, converters, and brand owners.

[0013] In another aspect, the present disclosure provides a biodegradable aqueous mixture for coating a substrate. According to one embodiment, the aqueous mixture comprises about 35 to about 75 weight percent water and about 25 to about 65 weight percent solids. The solids, in turn, are comprised of about 40 to about 99 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids. Further, the polyhydroxyalkanoate is in the form of polyhydroxyalkanoate particles having a moisture content of about 1 weight percent or more prior to mixing with water and a Dv(90) particle size of about 10 microns or less, as determined using ISO 8130-13:2019.

[0014] In some embodiments, the polyhydroxyalkanoate particles preferably have a moisture content of at least about 5% by weight prior to mixing with water.

[0015] According to certain embodiments, the polyhydroxyalkanoate particles preferably have a Dv(90) particle size of about 8 microns or less, as determined using ISO 8130-13:2019.

[0016] In some cases, the polyhydroxyalkanoate has a melting point, and the polyhydroxyalkanoate particles are preferably recovered from the biomass and subsequent purification processes such that the temperature of the polyhydroxyalkanoate particles does not exceed a temperature about 5° C. below the melting point of the polyhydroxyalkanoate (more preferably, about 10° C. below the melting point of the polyhydroxyalkanoate, and even more preferably, about 20° C. below the melting point of the polyhydroxyalkanoate), and then mixed with water to form an aqueous mixture.

[0017] According to certain embodiments, the polyhydroxyalkanoate particles are preferably recovered directly from the biomass and subsequent purification processes without being dried at a temperature above about 95° C., more preferably above about 50° C., and even more preferably above about 40° C., and then mixed with water to form an aqueous mixture.

[0018] In some embodiments, the mixture is in the form of a suspension, emulsion, or colloid.

[0019] According to some embodiments, the solids content is preferably comprised of about 40 to about 50 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids content.

[0020] In some embodiments, the mixture preferably contains about 45 to about 55 weight percent water and about 45 to about 55 weight percent solids.

[0021] According to certain embodiments, the polyhydroxyalkanoate preferably comprises a polyhydroxyalkanoate copolymer composed of about 75 to about 99 mole percent of monomeric repeat units of hydroxybutyrate and about 1 to about 25 mole percent of monomeric repeat units selected from the group consisting of hydroxyvalerate, hydroxyhexanoate, hydroxyoctanoate, and hydroxydecanoate.

[0022] In certain embodiments, the polyhydroxyalkanoate preferably comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HHx)"). More preferably, P(3HB-co-3HHx) is comprised of about 85 to about 98 mole percent hydroxybutyrate and about 2 to about 15 mole percent hydroxyhexanoate. In certain embodiments, P(3HB-co-3HHx) is more preferably comprised of about 88 to about 98 mole percent hydroxybutyrate and about 2 to about 12 mole percent hydroxyhexanoate. In other embodiments, P(3HB-co-3HHx) is more preferably comprised of about 93 to about 98 mole percent hydroxybutyrate and about 2 to about 7 mole percent hydroxyhexanoate.

[0023] According to some embodiments, the polyhydroxyalkanoate preferably comprises a polyhydroxyalkanoate terpolymer composed of about 75 to about 99.9 mole percent of monomeric repeat units of 3-hydroxybutyrate, about 0.1 to about 25 mole percent of monomeric repeat units of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent of monomeric repeat units of a third 3-hydroxyalkanoate having 5 to 12 carbon atoms.

[0024] According to certain embodiments, the polyhydroxyalkanoates preferably have a weight average molecular weight of from about 50,000 Daltons to about 2.5 million Daltons as determined by ASTM D5296-05.

[0025] In certain embodiments, the polyhydroxyalkanoates more preferably have a weight average molecular weight of from about 200,000 daltons to about 750,000 daltons, and even more preferably from about 300,000 daltons to about 550,000 daltons, as determined by ASTM D5296-05.

[0026] In some cases, the solids content also preferably comprises from about 1 weight percent to about 25 weight percent of a polymer selected from the group consisting of poly(lactic acid), poly(caprolactone), poly(ethylene sebacate), poly(butylene succinate), poly(butylene succinate-co-adipate), poly(butylene adipate terephthalate), poly(vinyl acetate), poly(vinyl alcohol), poly(3-hydroxypropionate), polysaccharides, and mixtures thereof.

[0027] In some embodiments, the solids more preferably also include poly(lactic acid).

[0028] According to some embodiments, the biodegradable aqueous mixture has a Brookfield viscosity, as measured according to ISO 1652, of about 1 to about 5,500 centipoise.

[0029] In yet another aspect, the present disclosure provides a method for making a coated substrate. According to one embodiment, the method includes providing a paperboard substrate having a first side and a second side. The method also includes applying a layer of an aqueous coating mixture onto at least the first side of the substrate.

[0030] The coating mixture applied is comprised of about 35 to about 75 weight percent water and about 25 to about 65 weight percent solids. The solids, in turn, are comprised of about 40 to about 99 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids. Further, the polyhydroxyalkanoate is in the form of polyhydroxyalkanoate particles having a moisture content of about 1 weight percent or greater prior to mixing with water and a Dv(90) particle size of about 10 microns or less, as determined using ISO 8130-13:2019.

[0031] The method also includes the step of curing the coating mixture to form a continuous coating layer comprising from about 40 to about 99 weight percent polyhydroxyalkanoate.

[0032] In certain embodiments, the polyhydroxyalkanoate particles preferably have a moisture content of at least about 5% by weight prior to mixing with water.

[0033] According to certain embodiments, the polyhydroxyalkanoate particles preferably have a Dv(90) particle size of about 8 microns or less, as determined using ISO 8130-13:2019.

[0034] In some cases, the polyhydroxyalkanoate has a melting point, and the polyhydroxyalkanoate particles are preferably recovered from the biomass and subsequent purification processes such that the temperature of the polyhydroxyalkanoate particles does not exceed a temperature about 5° C. below the melting point of the polyhydroxyalkanoate (more preferably, about 10° C. below the melting point of the polyhydroxyalkanoate, and even more preferably, about 20° C. below the melting point of the polyhydroxyalkanoate), and then mixed with water to form an aqueous mixture.

[0035] According to certain embodiments, the polyhydroxyalkanoate particles are preferably recovered directly from the biomass and subsequent purification processes without being dried at a temperature above about 95° C., more preferably above about 50° C., and even more preferably above about 40° C., and then mixed with water to form an aqueous mixture.

[0036] According to some embodiments, the coating mixture is preferably applied in the form of a dispersion, emulsion, or colloid.

[0037] According to some embodiments, the solids content is preferably comprised of about 40 to about 50 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids content.

[0038] In one particular embodiment, the coating mixture preferably contains about 45 to about 55 weight percent water and about 45 to about 55 weight percent solids.

[0039] In some cases, the polyhydroxyalkanoate preferably comprises a polyhydroxyalkanoate copolymer composed of about 75 to about 99 mole percent of monomeric repeat units of hydroxybutyrate and about 1 to about 25 mole percent of monomeric repeat units selected from the group consisting of hydroxyvalerate, hydroxyhexanoate, hydroxyoctanoate, and hydroxydecanoate.

[0040] According to certain embodiments, the polyhydroxyalkanoate preferably comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HHx)"). More preferably, P(3HB-co-3HHx) is comprised of about 85 to about 98 mole percent hydroxybutyrate and about 2 to about 15 mole percent hydroxyhexanoate. In certain embodiments, P(3HB-co-3HHx) is more preferably comprised of about 88 to about 98 mole percent hydroxybutyrate and about 2 to about 12 mole percent hydroxyhexanoate. In other embodiments, P(3HB-co-3HHx) is more preferably comprised of about 93 to about 98 mole percent hydroxybutyrate and about 2 to about 7 mole percent hydroxyhexanoate.

[0041] According to some embodiments, the polyhydroxyalkanoate preferably comprises a polyhydroxyalkanoate terpolymer composed of about 75 to about 99.9 mole percent of monomeric repeat units of 3-hydroxybutyrate, about 0.1 to about 25 mole percent of monomeric repeat units of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent of monomeric repeat units of a third 3-hydroxyalkanoate having 5 to 12 carbon atoms.

[0042] In certain embodiments, the polyhydroxyalkanoates preferably have a weight average molecular weight of from about 50,000 Daltons to about 2.5 million Daltons as determined by ASTM D5296-05.

[0043] According to certain embodiments, the polyhydroxyalkanoates more preferably have a weight average molecular weight of from about 200,000 Daltons to about 750,000 Daltons, and even more preferably from about 300,000 Daltons to about 550,000 Daltons, as determined by ASTM D5296-05.

[0044] In some embodiments, the solids content also preferably comprises from about 1 weight percent to about 25 weight percent of a polymer selected from the group consisting of poly(lactic acid), poly(caprolactone), poly(ethylene sebacate), poly(butylene succinate), poly(butylene succinate-co-adipate), poly(butylene adipate terephthalate), poly(vinyl acetate), poly(vinyl alcohol), poly(3-hydroxypropionate), polysaccharides, and mixtures thereof.

[0045] According to some embodiments, the coating mixture more preferably comprises poly(lactic acid).

[0046] In another aspect, the present disclosure provides a coated substrate prepared according to the aforementioned method.

[0047] In certain embodiments, the coating mixture preferably has a coating density of about 0.5 to about 50 grams / m 2 is applied to the first side of the substrate at a post-cure coating weight of 100%.

[0048] In one particular embodiment, the paperboard substrate is preferably impregnated with the coating mixture. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] The above needs and others are met by a method of forming polyhydroxyalkanoates (PHAs) that eliminates the heat drying process, the need for rewetting, the increased use of surfactants for dispersion, the increased energy utilization for high shear dispersion / sonication, and significant particle agglomeration that increases particle size compared to that obtained after dissolution. The resulting PHA is now referred to as PHA cake. The term "cake" is new in this disclosure and has not been used before in the PHA processing industry to describe an end-use material with the above characteristics.

[0050] The PHA cake made according to the methods described herein can be either water-based or solvent-based and is well suited for formulation into dispersions, colloids, suspensions, coatings, and similar materials. Moreover, this material is well suited for direct use in processes that utilize organic solvent and inorganic solvent systems. Examples of formulations made using this cake material include formulations such as barrier coatings and surface coatings. Additional examples of uses of this material include inclusion or embedding of electrolytes or materials in or on paper products, dispersions, colloids, emulsions, films, and heat seals. In certain embodiments, the PHA product is a dispersion of PHA in a liquid such as water or ethanol, but acts like an emulsion. In other embodiments, the PHA product can be in the form of a suspension, emulsion, or colloid.

[0051] PHA is created using steps similar to those of conventional biomass processes, except that after dissolution and protein extraction, the PHA is washed in an alternating fashion with organic and inorganic solvents (such as alcohol and water), with pressurization, final filtration, cross-flow filtration, decanting, or a combination of two of these, between the washing steps. In some embodiments, air or nitrogen sparging, preferably at room temperature, is also performed to obtain a PHA cake with a liquid content of about 5% by weight or more, in some embodiments, a PHA content of about 60(+ / -10)% by weight and a liquid content of 40(+ / -10)% by weight. In certain embodiments, the amount of moisture in the PHA cake can be about 1 weight percent or more.

[0052] As a result, the final PHA cake product can be used in a variety of different ways, such as by adding it to a mixer where water, surfactants, preservatives, rheology modifiers, thickeners, wetting agents, defoamers, biocides, weighting agents, binders, and dispersing agents are added, etc. These products can then be used in a variety of different ways, as described elsewhere herein.

[0053] Without undergoing a heat drying process that increases the temperature, the PHA cake retains reduced PHA particle size compared to standard PHA products that are heat dried to a solid. This particle size reduction further allows for better wetting of the PHA particles, less time / energy required to disperse the particles, less use of additives (i.e., surfactants) to prevent flocculation and particle agglomeration, and ultimately improves the processability, performance, and sustainability of the PHA material and the resulting material produced during application of the PHA cake in commercial processes. The smaller particles also improve the film-forming properties of the PHA particles as they reach their melting temperature and begin to flow onto the substrate to which they are applied.

[0054] The PHA cake is more suitable for the development of aqueous PHA (dispersion, emulsion, colloid, suspension, coating) formulations. Keeping the PHA wet reduces particle aggregation and flocculation, resulting in smaller particles that are easier to wet, disperse, and otherwise form aqueous formulations. In some embodiments, this approach keeps the particle size in the PHA cake below about 15 microns in diameter, with about 90% of the particles being less than 8 microns in size. In other embodiments, 90% of the particles may have a size less than 10 microns. Additionally, keeping the PHA in cake form without heat drying reduces the cost of production. PHA materials formed using the cake offer lower minimum film formation temperatures, lower dewatering rates, improved rheological profiles, and improved barrier performance compared to those made using PHA that has been dried to a powder state.

[0055] PHA cake can be used in a commercial context to develop water-based (or any solvent-based) coating materials. Coating refers to any dispersion, solution, emulsion, colloid, or suspension that contains PHA. The PHA cake itself can be sold to customers for future formulation, or it can be formulated after production and before sale to customers. Some end users of PHA cake include chemical manufacturers, paper and substrate manufacturers, molded fiber packaging companies, converters, and brand owners.

[0056] The present disclosure also provides a biodegradable aqueous mixture for coating a substrate, comprising the aforementioned PHA cake.

[0057] In general, the aqueous mixture can be in the form of either a suspension, an emulsion, or a colloid.

[0058] As used in this context, "suspension" refers to a heterogeneous mixture of at least two substances, the dispersed material and the dispersion medium. The particles of a suspension can be separated using filtration. The particles of a suspension also tend to settle under the influence of gravity compared to certain other mixtures (such as colloids).

[0059] As used herein, a "colloid" is a heterogeneous mixture whose particle size is intermediate between that of a solution and that of a suspension. The dispersed particles are spread evenly throughout the dispersion medium (i.e., liquid water). Particles present in colloids exhibit a light scattering phenomenon known as the Tyndall effect.

[0060] As used herein, an "emulsion" is a type of colloid in which an emulsifying agent (such as a surfactant) is present.

[0061] At the most common levels, the mixture includes water and solids. Typically, the mixture includes about 35 to about 75 weight percent water and about 25 to about 65 weight percent solids. In some cases, the mixture more preferably includes about 45 to about 55 weight percent water and about 45 to about 55 weight percent solids.

[0062] Thus, the solids content of the mixture includes at least a polyhydroxyalkanoate and may also include other biopolymers and / or additives. Typically, the solids content includes from about 40 to about 99 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids content. In some embodiments, the solids content more preferably includes from about 40 to about 50 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids content.

[0063] The polyhydroxyalkanoate is formed from the aforementioned PHA cake. As discussed above, such polyhydroxyalkanoate is recovered from biomass without subjecting the polyhydroxyalkanoate to extreme heat to dry the polyhydroxyalkanoate. Thus, the polyhydroxyalkanoate is in the form of polyhydroxyalkanoate particles having a moisture content of about 1% by weight or more before mixing with water. In some embodiments, the polyhydroxyalkanoate particles preferably have a moisture content of at least about 5% by weight before mixing with water.

[0064] The particles in the PHA cake are found to have a smaller average particle size compared to PHA powder that has been thoroughly dried. Specifically, the polyhydroxyalkanoate particles preferably have a Dv(90) particle size of about 10 microns or less, as determined using ISO 8130-13:2019. In some embodiments, the polyhydroxyalkanoate particles preferably have a Dv(90) particle size of about 8 microns or less, as determined using ISO 8130-13:2019. In comparison, particles of conventional PHA powder that has been thoroughly dried typically have a Dv(90) particle size of about 40 to about 180 microns, as determined using ISO 8130-13:2019.

[0065] Without being bound by theory, it is believed that the reduction in average size of the polyhydroxyalkanoate particles according to the present disclosure is due to the fact that the polyhydroxyalkanoate particles are not completely dried, but rather have a relatively high moisture content, and therefore are subjected to milder heating conditions when dried.

[0066] Specifically, care is taken to ensure that the temperature of the polyhydroxyalkanoate particles is maintained below the melting point of the polyhydroxyalkanoate particles during any drying operation. Generally, polyhydroxyalkanoates have a melting point, and the polyhydroxyalkanoate particles are preferably recovered from the biomass and subsequent purification processes such that the temperature of the polyhydroxyalkanoate particles does not exceed a temperature that is about 5°C below the melting point of the polyhydroxyalkanoate. In certain embodiments, the polyhydroxyalkanoate particles are preferably recovered from the biomass and subsequent purification processes such that the temperature of the polyhydroxyalkanoate particles does not exceed a temperature that is about 10°C below the melting point of the polyhydroxyalkanoate. In some cases, the polyhydroxyalkanoate particles are even more preferably recovered from the biomass and subsequent purification processes such that the temperature of the polyhydroxyalkanoate particles does not exceed a temperature that is about 20°C below the melting point of the polyhydroxyalkanoate.

[0067] Again, without being bound by theory, it is believed that when the particles are heated to their melting point, the smaller particles of polyhydroxyalkanoate tend to fuse together to form larger polyhydroxyalkanoate particles, whereas when the temperature is maintained well below the melting point of the polyhydroxyalkanoate, the polyhydroxyalkanoate particles tend to maintain a reduced average particle size.

[0068] It will be appreciated that since there are various forms of polyhydroxyalkanoate, the exact melting point of the polyhydroxyalkanoate particles will depend on which form of polyhydroxyalkanoate is present in the particle.

[0069] In general, the polyhydroxyalkanoate particles are typically recovered directly from the biomass and subsequent purification processes without being dried at a temperature above about 95° C. In certain embodiments, the polyhydroxyalkanoate particles are preferably recovered directly from the biomass and subsequent purification processes without being dried at a temperature above about 50° C. Even more preferably, the polyhydroxyalkanoate particles are recovered directly from the biomass and subsequent purification processes without being dried at a temperature above about 40° C.

[0070] Again, various forms of polyhydroxyalkanoates may be used in the PHA cake and aqueous mixtures formed therefrom. In some cases, the polyhydroxyalkanoates may be homopolymers (such as polyhydroxybutyrate). More typically, the polyhydroxyalkanoates are copolymers or terpolymers.

[0071] For example, in certain embodiments, the polyhydroxyalkanoate preferably comprises a polyhydroxyalkanoate copolymer composed of from about 75 to about 99 mole percent of monomeric repeat units of hydroxybutyrate and from about 1 to about 25 mole percent of monomeric repeat units selected from the group consisting of hydroxyvalerate, hydroxyhexanoate, hydroxyoctanoate, and hydroxydecanoate.

[0072] As an example, in certain embodiments, the polyhydroxyalkanoate preferably comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HHx)"). More preferably, the P(3HB-co-3HHx) comprises from about 85 to about 98 mole percent hydroxybutyrate and from about 2 to about 15 mole percent hydroxyhexanoate. In certain embodiments, the P(3HB-co-3HHx) more preferably comprises from about 88 to about 98 mole percent hydroxybutyrate and from about 2 to about 12 mole percent hydroxyhexanoate. In other embodiments, the P(3HB-co-3HHx) more preferably comprises from about 93 to about 98 mole percent hydroxybutyrate and from about 2 to about 7 mole percent hydroxyhexanoate.

[0073] In another embodiment, the polyhydroxyalkanoate preferably comprises a polyhydroxyalkanoate terpolymer composed of from about 75 to about 99.9 mole percent monomeric repeat units of 3-hydroxybutyrate, from about 0.1 to about 25 mole percent monomeric repeat units of 3-hydroxyhexanoate, and from about 0.1 to about 25 mole percent monomeric repeat units of a third 3-hydroxyalkanoate having from 5 to 12 carbon atoms.

[0074] In terms of molecular weight, the polyhydroxyalkanoates preferably have a weight average molecular weight of about 50,000 Daltons to about 2.5 million Daltons as determined by ASTM D5296-05. More preferably, the polyhydroxyalkanoates have a weight average molecular weight of about 200,000 Daltons to about 750,000 Daltons, and even more preferably, about 300,000 Daltons to about 550,000 Daltons as determined by ASTM D5296-05.

[0075] As noted above, the solids of the aqueous mixture may also include other biopolymers. In some cases, the solids preferably include from about 1 weight percent to about 25 weight percent of a polymer selected from the group consisting of poly(lactic acid), poly(caprolactone), poly(ethylene sebacate), poly(butylene succinate), poly(butylene succinate-co-adipate), poly(butylene adipate terephthalate), poly(vinyl acetate), poly(vinyl alcohol), poly(3-hydroxypropionate), polysaccharides, and mixtures thereof. In some cases, it is particularly preferred that the solids include poly(lactic acid).

[0076] Additionally, the aqueous mixture may contain various additives (such as preservatives, rheology modifiers, plasticizers, bulking agents, nucleating agents, dispersing agents, and wetting agents) to improve the stability of the aqueous mixture and / or to improve the material properties of the coated layer formed from the mixture. However, it has been surprisingly observed that aqueous mixtures using PHA cakes according to the present disclosure can be prepared using reduced amounts of additives compared to PHA mixtures prepared using PHA powders that have been thoroughly dried prior to mixing.

[0077] At the time of preparation, the biodegradable aqueous mixture typically has a Brookfield viscosity of about 1 to about 5,500 centipoise, as measured according to ISO 1652. More preferably, the biodegradable aqueous mixture has a Brookfield viscosity of about 100 to about 1200 centipoise, as measured according to ISO 1652. In certain embodiments, the biodegradable aqueous mixture still more preferably has a Brookfield viscosity of about 100 to about 500 centipoise, as measured according to ISO 1652.

[0078] The present disclosure also provides a method for making a coated substrate using the aforementioned aqueous mixture as a coating mixture, and a coated substrate prepared according to the method. According to the method, a paperboard substrate having both a first side and a second side is provided. Then, a layer of the aqueous coating mixture is applied onto at least the first side of the substrate. In some cases, the coating mixture may be applied onto both the first side and the second side of the substrate.

[0079] Finally, the coating mixture is cured to form a continuous coating layer comprising the polyhydroxyalkanoate. Curing of the coating layer is preferably accomplished by heating the substrate and coating to a temperature of about 105° C. to 145° C. so that water evaporates from the coating mixture and the solid particles fuse together into a continuous layer.

[0080] The coating mixture is as discussed above. Thus, the coating mixture applied generally contains about 35 to about 75 weight percent water and about 25 to about 65 weight percent solids, more preferably about 45 to about 55 weight percent water and about 45 to about 55 weight percent solids.

[0081] The solids content comprises from about 40 to about 99 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids content, and more preferably from about 40 to about 50 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids content.

[0082] Further, the polyhydroxyalkanoate is in the form of polyhydroxyalkanoate particles having a moisture content of about 1% by weight or more (more preferably, at least about 5% by weight) prior to mixing with water, and a Dv(90) particle size of about 10 microns or less (more preferably, about 8 microns) as determined using ISO 8130-13:2019.

[0083] For the final coated substrate, the coating mixture preferably has a coating density of about 0.5 to about 50 grams / m 2 is applied to the first side of the substrate at a post-cure coating weight of 100%.

[0084] As noted above, the coating layer may optionally be applied to both the first and second sides of the substrate.

[0085] Additionally, in some cases, the paperboard substrate may be completely impregnated with the coating mixture, which may be accomplished, for example, by metering the paperboard substrate with a size press.

[0086] Embodiment

[0087] The present disclosure is further illustrated by the following embodiments.

[0088] EMBODIMENT 1 1. A biodegradable aqueous mixture for coating a substrate, said mixture comprising: About 35 to about 75 percent by weight water and about 25 to about 65 percent by weight solids Including, the solids content comprises from about 40 to about 99 weight percent polyhydroxyalkanoate based on the total dry weight of the solids content; The biodegradable aqueous mixture, wherein the polyhydroxyalkanoate is in the form of polyhydroxyalkanoate particles having a moisture content of at least about 1% by weight prior to mixing with the water and a Dv(90) particle size of about 10 microns or less as determined using ISO 8130-13:2019.

[0089] EMBODIMENT 2 2. The biodegradable aqueous mixture of embodiment 1, wherein the polyhydroxyalkanoate particles have a moisture content of at least about 5% by weight prior to mixing with the water.

[0090] EMBODIMENT 3 3. The biodegradable aqueous mixture of embodiment 1 or 2, wherein the polyhydroxyalkanoate particles have a Dv(90) particle size of about 10 microns or less as determined using ISO 8130-13:2019.

[0091] EMBODIMENT 4 The biodegradable aqueous mixture of any of the preceding embodiments, wherein the polyhydroxyalkanoate has a melting point, and the polyhydroxyalkanoate particles are recovered from a biomass and subsequent purification process such that the temperature of the polyhydroxyalkanoate particles does not exceed a temperature about 5° C. below the melting point of the polyhydroxyalkanoate, more preferably about 10° C. below the melting point of the polyhydroxyalkanoate, and then mixed with the water to form the aqueous mixture.

[0092] EMBODIMENT 5 The biodegradable aqueous mixture of any of the preceding embodiments, wherein the polyhydroxyalkanoate particles are recovered from the biomass and subsequent purification processes such that the temperature of the polyhydroxyalkanoate does not exceed about 95°C, preferably about 50°C, more preferably about 40°C, and then mixed with the water to form the aqueous mixture.

[0093] EMBODIMENT 6 The biodegradable aqueous mixture of any of the preceding embodiments, wherein the mixture is in the form of a suspension, emulsion, or colloid.

[0094] EMBODIMENT 7 4. The biodegradable aqueous mixture of any of the preceding embodiments, wherein the solids content comprises about 40 to about 50 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids content.

[0095] EMBODIMENT 8 4. The biodegradable aqueous mixture of any of the preceding embodiments, wherein the mixture comprises about 45 to about 55 percent by weight water and about 45 to about 55 percent by weight solids.

[0096] EMBODIMENT 9 The biodegradable aqueous mixture of any of the preceding embodiments, wherein the polyhydroxyalkanoate comprises a polyhydroxyalkanoate copolymer comprising from about 75 to about 99 mole percent of monomeric repeat units of hydroxybutyrate and from about 1 to about 25 mole percent of monomeric repeat units selected from the group consisting of hydroxyvalerate, hydroxyhexanoate, hydroxyoctanoate, and hydroxydecanoate.

[0097] EMBODIMENT 10 2. The biodegradable aqueous mixture of any of the preceding embodiments, wherein the polyhydroxyalkanoate comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HHx)").

[0098] EMBODIMENT 11 11. The biodegradable aqueous mixture of embodiment 10, wherein the P(3HB-co-3HHx) comprises from about 85 to about 98 mole percent hydroxybutyrate and from about 2 to about 15 mole percent hydroxyhexanoate, more preferably from about 88 to about 98 mole percent hydroxybutyrate and from about 2 to about 12 mole percent hydroxyhexanoate, and even more preferably from about 93 to about 98 mole percent hydroxybutyrate and from about 2 to about 7 mole percent hydroxyhexanoate.

[0099] EMBODIMENT 12 9. The biodegradable aqueous mixture of any one of the preceding embodiments, wherein the polyhydroxyalkanoate comprises a polyhydroxyalkanoate terpolymer consisting of about 75 to about 99.9 mole percent of monomeric repeat units of 3-hydroxybutyrate, about 0.1 to about 25 mole percent of monomeric repeat units of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent of monomeric repeat units of a third 3-hydroxyalkanoate having 5 to 12 carbon atoms.

[0100] EMBODIMENT 13 2. The biodegradable aqueous mixture of any of the preceding embodiments, wherein the polyhydroxyalkanoate has a weight average molecular weight, as determined by ASTM D5296-05, of from about 50,000 Daltons to about 2.5 million Daltons, more preferably from about 200,000 Daltons to about 750,000 Daltons, and even more preferably from about 300,000 Daltons to about 550,000 Daltons.

[0101] EMBODIMENT 14 4. The biodegradable aqueous mixture of any of the preceding embodiments, wherein the solids further comprise from about 1 weight percent to about 25 weight percent, based on the total dry weight of the solids, of a polymer selected from the group consisting of poly(lactic acid), poly(caprolactone), poly(ethylene sebacate), poly(butylene succinate), poly(butylene succinate-co-adipate), poly(butylene adipate terephthalate), poly(vinyl acetate), poly(vinyl alcohol), poly(3-hydroxypropionate), polysaccharides, and mixtures thereof.

[0102] EMBODIMENT 15 4. The biodegradable aqueous mixture of any of the preceding embodiments, wherein the solids further comprise poly(lactic acid).

[0103] EMBODIMENT 16 4. The biodegradable aqueous mixture of any of the preceding embodiments, wherein the biodegradable aqueous mixture has a Brookfield viscosity of about 1 to about 5,500 centipoise, as measured according to ISO 1652.

[0104] EMBODIMENT 17 1. A method for making a coated substrate, comprising: providing a paperboard substrate having a first side and a second side; applying a layer of an aqueous coating mixture onto at least the first side of the substrate, the coating mixture applied comprises about 35 to about 75 weight percent water and about 25 to about 65 weight percent solids; the solids content comprises from about 40 to about 99 weight percent polyhydroxyalkanoate based on the total dry weight of the solids content; said applying step wherein said polyhydroxyalkanoate is in the form of polyhydroxyalkanoate particles having a moisture content of at least about 1% by weight prior to mixing with said water and a Dv(90) particle size of about 10 microns or less as determined using ISO 8130-13:2019; curing the coating mixture to form a continuous coating layer comprising from about 40 to about 99 weight percent polyhydroxyalkanoate; The method comprising:

[0105] EMBODIMENT 18 18. The method of embodiment 17, wherein the polyhydroxyalkanoate particles have a moisture content of at least about 5% by weight prior to mixing with the water.

[0106] EMBODIMENT 19 19. The method of embodiment 17 or 18, wherein the polyhydroxyalkanoate particles have a Dv(90) particle size of about 8 microns or less as determined using ISO 8130-13:2019.

[0107] EMBODIMENT 20 20. The method of any of embodiments 17-19, wherein the polyhydroxyalkanoate has a melting point, and the polyhydroxyalkanoate particles are recovered from a biomass and a subsequent purification process such that the temperature of the polyhydroxyalkanoate particles does not exceed a temperature about 5° C. below the melting point of the polyhydroxyalkanoate, more preferably about 10° C. below the melting point of the polyhydroxyalkanoate, and then mixed with the water to form the aqueous mixture.

[0108] EMBODIMENT 21 21. The method of any of embodiments 17-20, wherein the polyhydroxyalkanoate particles are recovered from the biomass and subsequent purification processes such that the temperature of the polyhydroxyalkanoate does not exceed about 95°C, preferably about 50°C, more preferably about 40°C, and then mixed with the water to form the aqueous mixture.

[0109] EMBODIMENT 22 22. The method according to any one of embodiments 17 to 21, wherein the coating mixture is applied in the form of a suspension, emulsion, or colloid.

[0110] EMBODIMENT 23 23. The method of any one of embodiments 17-22, wherein the solids comprise from about 40 to about 50 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids.

[0111] EMBODIMENT 24 24. The method of any one of claims 17-23, wherein the coating mixture comprises about 45 to about 55 weight percent water and about 45 to about 55 weight percent solids.

[0112] EMBODIMENT 25 25. The method of any one of embodiments 17-24, wherein the polyhydroxyalkanoate comprises a polyhydroxyalkanoate copolymer comprising from about 75 to about 99 mole percent of monomeric repeat units of hydroxybutyrate and from about 1 to about 25 mole percent of monomeric repeat units selected from the group consisting of hydroxyvalerate, hydroxyhexanoate, hydroxyoctanoate, and hydroxydecanoate.

[0113] EMBODIMENT 26 26. The method of any one of embodiments 17-25, wherein the polyhydroxyalkanoate comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HHx)").

[0114] EMBODIMENT 27 27. The method of embodiment 26, wherein the P(3HB-co-3HHx) comprises from about 85 to about 98 mole percent hydroxybutyrate and from about 2 to about 15 mole percent hydroxyhexanoate, more preferably from about 88 to about 98 mole percent hydroxybutyrate and from about 2 to about 12 mole percent hydroxyhexanoate, and even more preferably from about 93 to about 98 mole percent hydroxybutyrate and from about 2 to about 7 mole percent hydroxyhexanoate.

[0115] EMBODIMENT 28 25. The method of any one of embodiments 17-24, wherein the polyhydroxyalkanoate comprises a polyhydroxyalkanoate terpolymer consisting of from about 75 to about 99.9 mole percent monomeric repeat units of 3-hydroxybutyrate, from about 0.1 to about 25 mole percent monomeric repeat units of 3-hydroxyhexanoate, and from about 0.1 to about 25 mole percent monomeric repeat units of a third 3-hydroxyalkanoate having from 5 to 12 carbon atoms.

[0116] EMBODIMENT 29 29. The method of any one of embodiments 17-28, wherein the polyhydroxyalkanoate has a weight average molecular weight, as determined by ASTM D5296-05, of about 50,000 Daltons to about 2.5 million Daltons, more preferably about 200,000 Daltons to about 750,000 Daltons, and even more preferably about 300,000 Daltons to about 550,000 Daltons.

[0117] EMBODIMENT 30 30. The method of any of embodiments 17-29, wherein the solids further comprise from about 1 weight percent to about 25 weight percent, based on the total dry weight of the solids, of a polymer selected from the group consisting of poly(lactic acid), poly(caprolactone), poly(ethylene sebacate), poly(butylene succinate), poly(butylene succinate-co-adipate), poly(butylene adipate terephthalate), poly(vinyl acetate), poly(vinyl alcohol), poly(3-hydroxypropionate), polysaccharides, and mixtures thereof.

[0118] EMBODIMENT 31 31. The method of any one of embodiments 17-30, wherein the solids further comprise poly(lactic acid).

[0119] EMBODIMENT 32 18. A coated substrate prepared according to the method of embodiment 17.

[0120] EMBODIMENT 33 The coating mixture has a density of about 0.5 to about 50 grams / m 2 33. The coated substrate of embodiment 32, wherein the first side of the substrate is applied at a post-cure coating weight of

[0121] EMBODIMENT 34 34. The coated substrate of embodiment 32 or 33, wherein the paperboard substrate is impregnated with the coating mixture.

[0122] EMBODIMENT 35 1. A polyhydroxyalkanoate (PHA) cake formed directly from biomass and a subsequent purification process without any thermal drying step, said PHA cake having a moisture content of about 5% by weight or more and a Dv(90) particle size of about 8 microns or less.

[0123] EMBODIMENT 36 A PHA cake formed directly from biomass and a subsequent purification process without any heat drying step, said PHA cake having a moisture content of about 5% by weight or greater and a Dv(90) particle size of greater than about 8 microns.

[0124] EMBODIMENT 37 A PHA cake according to embodiment 35 or 36, wherein they are integrated as a mixture of particle sizes or a matrix of particles to provide a liquid barrier when temporary closure is required.

[0125] EMBODIMENT 38 36. The PHA cake of embodiment 35, comprising a homopolymer PHA, a copolymer PHA, a block copolymer PHA, a branched copolymer PHA, and a terpolymer PHA, or a combination thereof.

[0126] EMBODIMENT 39 36. The PHA cake of embodiment 35, comprising at least one of short chain PHAs, medium chain PHAs, and long chain PHAs, such as butyrate, propionate, valerate, hexanoate, octanoate, and decanoate.

[0127] EMBODIMENT 40 The PHA cake of embodiment 35, wherein the PHA cake comprises a final dry mass content of about 30% to about 95% by weight.

[0128] EMBODIMENT 41 The PHA cake of embodiment 35, wherein the PHA is formed in a biological process.

[0129] EMBODIMENT 42 The PHA cake of embodiment 35, wherein the PHA is formed by fermentation.

[0130] EMBODIMENT 43 The PHA cake of embodiment 35, wherein the PHA is formed via reactive synthesis.

[0131] EMBODIMENT 44 36. The PHA cake of embodiment 35, comprising a PHA content of about 30% to about 95% by weight.

[0132] EMBODIMENT 45 The PHA cake of embodiment 35, wherein the PHA is produced from a combination of biological and non-biological processes.

[0133] EMBODIMENT 46 The PHA cake of embodiment 35, wherein the PHA cake, after being separated and purified from production precursors, is filtered through at least one of a mechanical dewatering system and a mechanical desolventizing system.

[0134] EMBODIMENT 47 The PHA cake of embodiment 35, wherein the PHA cake is mechanically dewatered using at least one of an organic solvent, an inorganic solvent, and a solvent-free system.

[0135] EMBODIMENT 48 The PHA cake of embodiment 35, wherein the PHA cake is mechanically dewatered using a multi-stage process.

[0136] EMBODIMENT 49 The PHA cake of embodiment 35, wherein the PHA cake is used in a non-extrusion based process or application.

[0137] EMBODIMENT 50 The PHA cake of embodiment 35, wherein the PHA cake is used in at least one of an aqueous coating, a solvent coating, an emulsion, a dispersion, a colloid, an electrolyte, and a suspension.

[0138] EMBODIMENT 51 The PHA cake of embodiment 35, wherein the PHA cake is used in at least one of water-based coatings, solvent-based coatings, dispersions, colloids, suspensions, and emulsions used in at least one of inks, barrier coatings, surface coatings, embedding coatings, paper products, films, heat seals, cosmetics, personal care, home care, water treatment, filtration, media, water-resistant coatings, and oil-resistant coatings.

[0139] EMBODIMENT 52 A polyhydroxyalkanoate (PHA) cake comprising: Biological production of PHA and Dissolution and Removal of cell debris; purifying said PHA by alternating washing with organic and inorganic liquids; Pressurizing / decanting the PHA during the washing; Partially drying the PHA with room temperature gas without any heat drying step; thereby producing said PHA cake having a moisture content of about 5% by weight or more and a controlled application-specific particle size; The PHA cake formed by:

[0140] As used herein, the phrase "at least one of A, B, and C" means that there is at least one A or one B or one C, although all combinations of absence or multiple occurrence of each of A, B, and C are possible. Examples include, but are not limited to: Ax1, Ax2+Bx1, Cx2, Ax1+Bx1+Cx1, Ax7+Bx12+Cx113. The phrase does not mean Ax0+Bx0+Cx0.

[0141] The foregoing description of the embodiments for the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments have been chosen and described in an effort to provide illustration of the principles of the invention and its practical application, thereby enabling others skilled in the art to utilize the invention in various embodiments, with various modifications made to suit the specific uses contemplated. All such modifications and variations are within the scope of the invention, as determined by the appended claims, when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

1. 1. A method for making a biodegradable aqueous mixture for coating a substrate, said method comprising: Biological production of polyhydroxyalkanoates; Dissolution and Removal of cell debris; Purification of the polyhydroxyalkanoate by alternate washing with organic and inorganic liquids; Pressurizing / decanting the polyhydroxyalkanoate during the washing; partially drying the polyhydroxyalkanoate with room temperature gas without any heat drying step to produce polyhydroxyalkanoate particles having a moisture content of at least 1% by weight and a Dv(90) particle size of 10 microns or less as determined using ISO 8130-13:2019; mixing the polyhydroxyalkanoate particles with water to form a biodegradable aqueous mixture comprising about 35 to about 75 weight percent water and about 25 to about 65 weight percent solids; Including, The process wherein the solids comprise 40 to 99 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids.

2. 10. The method of claim 1, wherein the polyhydroxyalkanoate particles have a moisture content of at least 5% by weight prior to mixing with the water.

3. 10. The method of claim 1, wherein the polyhydroxyalkanoate particles have a Dv(90) particle size of 8 microns or less as determined using ISO 8130-13:2019.

4. 2. The method of claim 1, wherein the polyhydroxyalkanoate has a melting point, and the polyhydroxyalkanoate particles are recovered from the biomass and a subsequent purification process such that the temperature of the polyhydroxyalkanoate particles does not exceed 5° C. below the melting point of the polyhydroxyalkanoate, and then mixed with the water to form the aqueous mixture.

5. 10. The method of claim 1, wherein the polyhydroxyalkanoate particles are recovered from biomass and a subsequent purification process such that the temperature of the polyhydroxyalkanoate particles does not exceed 95°C, and then mixed with the water to form the aqueous mixture.

6. The method of claim 1 , wherein the mixture is in the form of a suspension, emulsion, or colloid.

7. 10. The method of claim 1, wherein the solids comprise 40 to 50 weight percent polyhydroxyalkanoate, based on the total dry weight of the solids.

8. The method of claim 1, wherein the mixture comprises 45 to 55 weight percent water and 45 to 55 weight percent solids.

9. 10. The method of claim 1, wherein the polyhydroxyalkanoate comprises a polyhydroxyalkanoate copolymer comprising 75 to 99 mole percent of monomeric repeat units of hydroxybutyrate and 1 to 25 mole percent of monomeric repeat units selected from the group consisting of hydroxyvalerate, hydroxyhexanoate, hydroxyoctanoate, and hydroxydecanoate.

10. 2. The method of claim 1, wherein the polyhydroxyalkanoate comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HHx)").

11. 11. The method of claim 10, wherein the P(3HB-co-3HHx) comprises 85 to 98 mole percent hydroxybutyrate and 2 to 15 mole percent hydroxyhexanoate.

12. 2. The method of claim 1, wherein the polyhydroxyalkanoate comprises a polyhydroxyalkanoate terpolymer consisting of 75 to 99.9 mole percent monomeric repeat units of 3-hydroxybutyrate, 0.1 to 25 mole percent monomeric repeat units of 3-hydroxyhexanoate, and 0.1 to 25 mole percent monomeric repeat units of a third 3-hydroxyalkanoate having 5 to 12 carbon atoms.

13. 10. The method of claim 1, wherein the polyhydroxyalkanoate has a weight average molecular weight of 50,000 to 2.5 million daltons as determined by ASTM D5296-05.

14. 10. The method of claim 1, wherein the solids further comprise from 1 weight percent to 25 weight percent, based on the total dry weight of the solids, of a polymer selected from the group consisting of poly(lactic acid), poly(caprolactone), poly(ethylene sebacate), poly(butylene succinate), poly(butylene succinate-co-adipate), poly(butylene adipate terephthalate), poly(vinyl acetate), poly(vinyl alcohol), poly(3-hydroxypropionate), polysaccharides, and mixtures thereof.

15. The method of claim 1 , wherein the solids further comprise poly(lactic acid).

16. 10. The method of claim 1, wherein the biodegradable aqueous mixture has a Brookfield viscosity of 1 to 5,500 centipoise, as measured in accordance with ISO 1652.