A polyhydroxyalkanoate water-based coating and its preparation method and application

Abstract

The present invention provides a polyhydroxyalkanoate water-based coating and a preparation method and application thereof, wherein the polyhydroxyalkanoate water-based coating comprises a polyhydroxyalkanoate suspension and an auxiliary agent; wherein the melting point of the polyhydroxyalkanoate is 100-120°C, and the polyhydroxyalkanoate comprises a copolymer of at least two polymerized monomers. The present invention selects polyhydroxyalkanoates that meet specific conditions, and the water-based coating prepared thereby can be used for coating paper, etc. The water-based coating is environmentally friendly and degradable, and the prepared coated paper can be directly pulped and reused, without the need for separation of the coating and the pulp, and without separation cost investment. The coated paper obtained by the present invention has good comprehensive properties such as static stability, temperature resistance, oil resistance, environmental protection, and coating flatness, and does not require an adhesive to glue the coating to a substrate such as base paper, and can meet the requirements of containing high-temperature liquids.

Description

Technical Field

[0001] The invention relates to the field of biodegradable polymer materials, and in particular to a polyhydroxyalkanoate water-based coating and a preparation method and application thereof. Background Art

[0002] In daily life, people use many waterproof and anti-penetration products, such as paper cups, which are made by coating a layer of plastic on a base paper layer. Existing paper cups usually use PE coating layer, PLA coating layer or acrylic water-based coating, but they each have their own disadvantages. The PE coating layer cannot be degraded, pollutes the environment, and the separation of the paper layer and the coating layer consumes a lot of energy and requires a large investment. The PLA coating layer cannot be naturally degraded, the paper layer and the coating layer cannot be separated, and the pulp cannot be directly reused. With acrylic water-based coating, the pulp can be directly reused, but acrylic acid cannot be degraded, and pollution such as microplastics is generated.

[0003] Polyhydroxyalkanoate (PHA) is an intracellular polyester synthesized by many bacteria. As a biosynthetic polymer thermoplastic material, it has physical and chemical properties similar to those of synthetic plastics and many excellent properties that synthetic plastics do not have, such as biodegradability, biocompatibility, optical activity, piezoelectricity, gas barrier properties, etc.

[0004] Since polyhydroxyalkanoates are biodegradable, researchers have tried to use polyhydroxyalkanoate water-based coatings to replace existing PE coatings, PLA coatings, and acrylic water-based coatings to achieve environmental protection and safety. However, the existing polyhydroxyalkanoate water-based coatings must be dried at 160-180°C when forming a film, and high temperatures can cause paper deformation and yellowing problems. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a polyhydroxyalkanoate water-based coating and a preparation method and application thereof. The polyhydroxyalkanoate water-based coating can meet the processing conditions of paper to obtain a qualified and environmentally friendly waterproof and anti-penetration product.

[0006] In a first aspect, the present invention provides a polyhydroxyalkanoate water-based coating, comprising: a polyhydroxyalkanoate suspension and an additive;

[0007] The melting point of the polyhydroxyalkanoate is 100-120° C., and the polyhydroxyalkanoate comprises a copolymer of at least two polymerizable monomers.

[0008] The present invention has found that by selecting the above-mentioned specific polyhydroxyalkanoates, the water-based coating prepared can be coated on paper without using the traditional high-temperature film-forming process, but can form a film at a temperature not exceeding 150°C. Some water-based coatings can even be dried at 60-120°C after being prepared, thus avoiding the problems of paper deformation and yellowing caused by high temperature.

[0009] The polymerizable monomers are divided into short chains (3-5 carbons) and medium-long chains (6-14 carbons) according to the number of carbon atoms. Specifically, the polymerizable monomers include one or more of 3-hydroxypropionic acid, 3-hydroxybutyric acid (3HB), 4-hydroxybutyric acid (4HB), 3-hydroxyvaleric acid (3HV), 5-hydroxyvaleric acid (5HV), 3-hydroxyhexanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid or 3-hydroxydodecanoic acid.

[0010] In order to form a film at a temperature not exceeding 150° C., when the polymerization monomer includes 4HB, the monomer content of 4HB is 21%-30%.

[0011] When the polymerized monomer includes 3HV, the monomer content of 3HV is 5% to 20%.

[0012] When the polymerized monomer includes 5HV, the monomer content of 5HV is 5% to 20%.

[0013] In some embodiments of the present invention, the polyhydroxyalkanoate comprises a copolymer of two polymerized monomers, that is, PHA comprises a dimer. The dimer is selected from one or more of P34HB, PHBV, PHBHHx, PHBHO, and PHBHN.

[0014] Among them, the monomer content of 4HB in P34HB is any value between 21% and 30%, for example, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, and 30%.

[0015] The monomer content of 3HV in PHBV is any value between 5% and 20%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%.

[0016] The monomer content of 3HHx in PHBHHx is any value between 1% and 99%, for example, 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, and 99%.

[0017] The monomer content of 3HO in PHBHO is any value between 1% and 99%, for example, 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, and 99%.

[0018] The monomer content of 3HN in PHBHN is any value between 1% and 99%, for example, 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99%.

[0019] In some other embodiments of the present invention, the polyhydroxyalkanoate comprises a copolymer of three polymerized monomers, that is, PHA comprises a trimer, and the trimer is selected from one or more of P3HB4HB3HV and P3HB4HB5HV.

[0020] Among them, the monomer content of 4HB in P3HB4HB3HV is any value between 21% and 30%, for example, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, and 30%; the monomer content of 3HV is any value between 5% and 20%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%.

[0021] The monomer content of 4HB in P3HB4HB5HV is any value between 21% and 30%, for example, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, and 30%; the monomer content of 5HV is any value between 5% and 20%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%.

[0022] The polyhydroxyalkanoate water-based coating of the present invention is suitable for coating paper, and the processing tolerance temperature of the paper is above the melting point of the polyhydroxyalkanoate and below 150°C.

[0023] It should be noted that the processing tolerance temperature refers to the temperature at which the paper is processed without deformation and yellowing due to heat, which affects the appearance and performance. In other words, the paper described in the present invention includes conventional paper with a processing tolerance temperature above the melting point of polyhydroxyalkanoates and below 150°C, such as white cardboard, gray board, coated paper, offset paper, corrugated paper, writing paper, kraft paper, and newsprint, but does not include special paper with a processing tolerance temperature higher than 150°C.

[0024] In some embodiments of the present invention, the paper used is white cardboard.

[0025] In some embodiments of the present invention, the polyhydroxyalkanoate suspension is obtained by dispersing PHA powder in water.

[0026] In other embodiments of the present invention, the polyhydroxyalkanoate suspension is a PHA solution obtained by centrifugal extraction of PHA fermentation broth; preferably, the centrifugal extraction includes a cell wall breaking treatment; further preferably, the particle size of PHA in the PHA solution is less than 1 micron.

[0027] It is a common practice to first prepare PHA powder (usually with a particle size of 0.1-5 microns) by biological fermentation, and then disperse it in water to obtain a PHA aqueous solution. However, in order to obtain a better dispersion effect and avoid agglomeration, the present invention has found that the PHA solution obtained by centrifugal extraction of PHA fermentation broth can be directly used as a raw material for preparing water-based coatings.

[0028] Furthermore, in a specific embodiment of the present invention, in the polyhydroxyalkanoate suspension, the mass fraction of polyhydroxyalkanoate is 30-70%, and the amount of the additive added does not exceed 5% of the mass of the polyhydroxyalkanoate suspension.

[0029] The polyhydroxyalkanoate water-based coating of the present invention can add as few additives as possible, and the amount of the additive added does not exceed 5% of the mass of the polyhydroxyalkanoate suspension, which is better than the existing level. Since polyhydroxyalkanoate is hydrophobic, it is traditionally dispersed with an organic solvent, which is toxic and harmful. In order to ensure stability, a large amount of additives are usually added to the water-based system developed later. Since the PHA itself has a small particle size, has good dispersibility in water, and has good film-forming and leveling properties, the amount of additives added can be reduced.

[0030] In some embodiments of the present invention, the auxiliary agent includes one or more of a film former, a wetting agent, a leveling agent, and a thickener.

[0031] Preferably, the above four additives are all added to the polyhydroxyalkanoate water-based coating.

[0032] Further preferably, based on the mass of the polyhydroxyalkanoate suspension, the added amount of the film former is 0.1-1%, the added amount of the wetting agent is 0.1-1%, the added amount of the leveling agent is 0.1-1%, and the added amount of the thickener is 0.1-1%.

[0033] In some embodiments of the present invention, the film-forming agent is selected from one or more of diethanol ether, propylene glycol ether, and N-methylpyrrolidone.

[0034] In some embodiments of the present invention, the wetting agent is selected from one or more of alkyl nonylphenol ethoxylate, potassium dodecyl phosphate, sodium dodecyl polyoxyethylene ether sulfate, sodium lauroyl acid, and sodium α-olefin sulfonate.

[0035] In some embodiments of the present invention, the leveling agent is selected from one or more of Digo 432, modified polysiloxane, and cellulose.

[0036] In some embodiments of the present invention, the thickener is selected from one or more of gelatinized starch, polyacrylonitrile, sodium dodecylbenzene sulfonate, sodium polyacrylate, sodium alginate, and polypyrrolidone; preferably, the gelatinized starch is selected from one or more of corn starch, potato starch, sweet potato starch, and cassava starch.

[0037] In a second aspect, the present invention provides a method for preparing the above-mentioned polyhydroxyalkanoate water-based coating.

[0038] The preparation method provided by the invention comprises: dispersing an auxiliary agent into the polyhydroxyalkanoate suspension to form a colloidal dispersed solution.

[0039] The preparation method of the invention has low cost, simple production process and is easy for industrial production.

[0040] The dispersion can be carried out by mechanical stirring or ultrasonic dispersion, which are commonly used in the art. Preferably, when mechanical stirring is used, the rotation speed is controlled at about 2000 rpm. When ultrasonic dispersion is used, the dispersion time is controlled at about 30 min.

[0041] In a third aspect, the present invention provides the use of the above-mentioned polyhydroxyalkanoate water-based coating in the preparation of an anti-penetration material.

[0042] Specifically, the present invention provides an anti-permeation paper, comprising paper and a coating coated on the paper, wherein the coating is made of the above-mentioned polyhydroxyalkanoate water-based coating.

[0043] In some embodiments of the present invention, the paper is white cardboard.

[0044] In some embodiments of the present invention, the coating has a thickness of 3-14 microns.

[0045] In some embodiments of the present invention, the method for preparing the anti-permeation paper includes: applying the polyhydroxyalkanoate water-based coating on the paper, controlling the coating wet material thickness to 10-20 microns, drying at 60-65°C for 1-1.5 hours after coating, and then drying at 120-150°C for no more than 1 minute to obtain an anti-permeation paper with a coating dry thickness of 3-14 microns.

[0046] Among them, the water-based paint can be applied by common equipment such as a wire rod coater, a smooth plate coating roller, or a gravure coating roller.

[0047] In addition, it should be noted that the anti-penetration paper of the present invention is not only waterproof but also oil-proof, and has temperature resistance and permeability resistance. After being made into a paper cup, it can be used to hold high-temperature liquids.

[0048] The present invention provides a polyhydroxyalkanoate water-based coating, a preparation method and application thereof. The water-based coating prepared by selecting polyhydroxyalkanoate meeting specific conditions can be used for coating paper, etc. The water-based coating is environmentally friendly and degradable. The prepared coated paper can be directly pulped and reused without separation of coating and pulp, and no separation cost investment is required.

[0049] Furthermore, the coated paper obtained by the present invention has good comprehensive properties such as static stability, temperature resistance, oil resistance, environmental protection, and coating smoothness. It does not require adhesives to glue the coating to substrates such as base paper, and can meet the requirements of containing high-temperature liquids. DETAILED DESCRIPTION

[0050] The term "include" or "comprising" in the present invention is an open description containing the specified components or steps described, and other specified components or steps that will not be substantially affected.

[0051] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0052] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "specific implementations", or "some specific implementations" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0053] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0055] The Chinese full names of the English abbreviations appearing in this article are as follows:

[0056] PHA: Polyhydroxyalkanoate

[0057] P4HB: Poly-4-hydroxybutyrate

[0058] PHBV: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

[0059] P3HB4HB or P34HB: poly(3-hydroxybutyrate-co-4-hydroxybutyrate)

[0060] PHBHHx: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)

[0061] PHBHO: Poly(3-hydroxybutyrate-co-3-hydroxyoctanoate)

[0062] PHBHN: Poly(3-hydroxybutyrate-co-3-hydroxynonanoate)

[0063] P3HB4HB3HV: poly(3-hydroxybutyrate-co-4-hydroxybutyrate-co-3-hydroxyvalerate)

[0064] P3HB4HB5HV: poly(3-hydroxybutyrate-co-4-hydroxybutyrate-co-5-hydroxyvalerate).

[0065] In the following examples, the test method for heat resistance is as follows: add a certain mass of water at a specified temperature (100°C) to the heat-sealed paper cups, add to about 6mm from the plane of the cup mouth, then place the cups filled with water on a flat glass plate, let it stand for 1 hour, and observe whether the coating of the paper cups has bubbling, shedding, etc. For each sample, 5 paper cups are tested, and if the coating of one of the paper cups has bubbling, shedding, etc., it is judged to be unqualified.

[0066] The test method for corn oil resistance is: add a certain mass of corn oil at a specified temperature (23℃ or 100℃) to the heat-sealed paper cups, add to about 6mm from the cup mouth, then place the cup containing corn oil on a flat glass plate, let it stand for 1 hour, and observe whether there is leakage in the paper cup. Five paper cups are tested for each sample, and if one of them leaks, it is judged as unqualified.

[0067] Example 1

[0068] This embodiment provides a polyhydroxyalkanoate water-based coating, and the preparation method thereof is as follows:

[0069] Weigh 30 parts by mass of P34HB (melting point 112° C., 4-hydroxybutyric acid content 21%) powder (particle size 1 micron), add it to 70 parts by mass of water, stir at a speed of 2000 rpm, and disperse for 30 minutes to uniformly disperse the polyhydroxyalkanoate in the water, then add 0.1 parts by mass of diethanol ether, 0.1 parts by mass of alkyl nonylphenol ethoxylate, 0.1 parts by mass of Digo 432 and 0.1 parts by mass of sodium alginate, stir at a speed of 2000 rpm, and disperse for 30 minutes to uniformly disperse the additives to form a colloidal, uniformly dispersed dilute solution, thereby obtaining a water-based coating of polyhydroxyalkanoate.

[0070] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 20 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 150°C for 1 minute to obtain an anti-penetration paper with a coating dry thickness of 6 μm.

[0071] The viscosity and static stability of the obtained polyhydroxyalkanoate water-based coating were tested, and the heat resistance and corn oil resistance of the obtained waterproof paper were tested. The results are shown in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] Example 2

[0076] This embodiment provides a polyhydroxyalkanoate water-based coating, and the preparation method thereof is as follows:

[0077] Weigh 70 parts by mass of P34HB (melting point 105° C., 4-hydroxybutyric acid content 25%) powder (particle size 3 μm), add it to 30 parts by mass of water, use ultrasound for ultrasonic dispersion, and disperse for 30 minutes to evenly disperse the polyhydroxyalkanoate in the water. Then add 0.5 parts by mass of propylene glycol ether, 0.5 parts by mass of potassium dodecyl phosphate, 0.5 parts by mass of modified polysiloxane and 0.5 parts by mass of polypyrrolidone, stir at a speed of 2000 rpm, and disperse for 30 minutes to evenly disperse the additives to form a colloidal, evenly dispersed dilute solution, thereby obtaining a water-based coating of polyhydroxyalkanoate.

[0078] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 10 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 110°C for 0.5 min to obtain an anti-penetration paper with a coating dry thickness of 7 μm.

[0079] The viscosity and static stability of the obtained polyhydroxyalkanoate water-based coating were tested, and the heat resistance and corn oil resistance of the obtained waterproof paper were tested. The results are shown in Table 2.

[0080] Table 2

[0081]

[0082]

[0083] Example 3

[0084] This embodiment provides a polyhydroxyalkanoate water-based coating, and the preparation method thereof is as follows:

[0085] Weigh 35 parts by mass of P34HB (melting point 101° C., 4-hydroxybutyric acid content 30%) powder (particle size 5 μm), add it to 65 parts by mass of water, use ultrasound for ultrasonic dispersion, and disperse for 30 minutes to evenly disperse the polyhydroxyalkanoate in the water. Then add 1 part by mass of N-methylpyrrolidone, 1 part by mass of sodium lauroyl acid, 1 part by mass of cellulose and 1 part by mass of corn starch, stir at a speed of 2000 rpm, and disperse for 30 minutes to evenly disperse the additives to form a colloidal, evenly dispersed dilute solution, thereby obtaining a water-based coating of polyhydroxyalkanoate.

[0086] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 15 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 130°C for 1 minute to obtain an anti-penetration paper with a coating dry thickness of 6 μm.

[0087] The viscosity and static stability of the obtained polyhydroxyalkanoate water-based coating were tested, and the heat resistance and corn oil resistance of the obtained waterproof paper were tested. The results are shown in Table 3.

[0088] Table 3

[0089] Test items result Viscosity (mPa.s) 520 Stability at room temperature for 24 hours Unstratified Temperature resistance (℃) 100℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? yes Is it recyclable and degradable? yes Can it be re-pulped? yes

[0090] Example 4

[0091] This embodiment provides a polyhydroxyalkanoate water-based coating, and the preparation method thereof is as follows:

[0092] Weigh 70 parts by mass of PHBV (melting point 110° C., 3-hydroxyvaleric acid content 20%) powder (particle size 0.2 μm), add it to 30 parts by mass of water, use ultrasound for ultrasonic dispersion, and disperse for 30 minutes to uniformly disperse the polyhydroxyalkanoate in the water. Then add 0.5 parts by mass of propylene glycol ether, 0.5 parts by mass of potassium dodecyl phosphate, 0.5 parts by mass of modified polysiloxane and 0.5 parts by mass of polypyrrolidone, stir at a speed of 2000 rpm, and disperse for 30 minutes to uniformly disperse the additives to form a colloidal, uniformly dispersed dilute solution, thereby obtaining a water-based coating of polyhydroxyalkanoate.

[0093] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 10 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 110°C for 1 minute to obtain an anti-penetration paper with a coating dry thickness of 7 μm.

[0094] The viscosity and static stability of the obtained polyhydroxyalkanoate water-based coating were tested, and the heat resistance and corn oil resistance of the obtained waterproof paper were tested. The results are shown in Table 4.

[0095] Table 4

[0096] Test items result Viscosity (mPa.s) 340 Stability at room temperature for 24 hours Unstratified Temperature resistance (℃) 100℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? yes Is it recyclable and degradable? yes Can it be re-pulped? yes

[0097] Example 5

[0098] This embodiment provides a polyhydroxyalkanoate water-based coating, and the preparation method thereof is as follows:

[0099] Weigh 70 parts by mass of PHBHHx (melting point 108°C, 3-hydroxycaproic acid content 40%) powder (particle size 0.5 micron), add it to 30 parts by mass of water, use ultrasound for ultrasonic dispersion, and disperse for 30 minutes to evenly disperse the polyhydroxyalkanoate in the water. Then add 0.5 parts by mass of propylene glycol ether, 0.5 parts by mass of potassium dodecyl phosphate, 0.5 parts by mass of modified polysiloxane and 0.5 parts by mass of polypyrrolidone, stir at a speed of 2000 rpm, and disperse for 30 minutes to evenly disperse the additives to form a colloidal, evenly dispersed dilute solution, thereby obtaining a water-based coating of polyhydroxyalkanoate.

[0100] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 10 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 110°C for 1 minute to obtain an anti-penetration paper with a coating dry thickness of 7 μm.

[0101] The viscosity and static stability of the obtained polyhydroxyalkanoate water-based coating were tested, and the heat resistance and corn oil resistance of the obtained waterproof paper were tested. The results are shown in Table 5.

[0102] Table 5

[0103] Test items result Viscosity (mPa.s) 330 Stability at room temperature for 24 hours Unstratified Temperature resistance (℃) 100℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? yes Is it recyclable and degradable? yes Can it be re-pulped? yes

[0104] Example 6

[0105] This embodiment provides a polyhydroxyalkanoate water-based coating, and the preparation method thereof is as follows:

[0106] Weigh 40 parts by mass of PHBHHx (melting point 108° C., 3-hydroxyhexanoic acid content 10%) and 30 parts by mass of P34HB (melting point 112° C., 4-hydroxybutyric acid content 21%) powder (particle size 0.5 μm), add them to 30 parts by mass of water, use ultrasound for ultrasonic dispersion, and disperse for 30 minutes to uniformly disperse the polyhydroxyalkanoate in the water. Then add 0.5 parts by mass of propylene glycol ether, 0.5 parts by mass of potassium dodecyl phosphate, 0.5 parts by mass of modified polysiloxane and 0.5 parts by mass of polypyrrolidone, stir at a speed of 2000 rpm, and disperse for 30 minutes to uniformly disperse the additives to form a colloidal, uniformly dispersed dilute solution, thereby obtaining a water-based coating of polyhydroxyalkanoate.

[0107] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 10 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 110°C for 1 minute to obtain an anti-penetration paper with a coating dry thickness of 7 μm.

[0108] The viscosity and static stability of the obtained polyhydroxyalkanoate water-based coating were tested, and the heat resistance and corn oil resistance of the obtained waterproof paper were tested. The results are shown in Table 6.

[0109] Table 6

[0110] Test items result Viscosity (mPa.s) 360 Stability at room temperature for 24 hours Unstratified Temperature resistance (℃) 100℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? yes Is it recyclable and degradable? yes Can it be re-pulped? yes

[0111] Example 7

[0112] This embodiment provides a polyhydroxyalkanoate water-based coating, and the preparation method thereof is as follows:

[0113] Weigh 70 parts by mass of P3HB4HB3HV (4-hydroxybutyric acid content 22%, 3-hydroxyvaleric acid content 10%) powder (particle size 0.5 micron), add it to 30 parts by mass of water, use ultrasound for ultrasonic dispersion, and disperse for 30 minutes to evenly disperse the polyhydroxyalkanoate in the water. Then add 0.5 parts by mass of propylene glycol ether, 0.5 parts by mass of potassium dodecyl phosphate, 0.5 parts by mass of modified polysiloxane and 0.5 parts by mass of polypyrrolidone, stir at a speed of 2000 rpm, and disperse for 30 minutes to evenly disperse the additives to form a colloidal, evenly dispersed dilute solution, thereby obtaining a water-based coating of polyhydroxyalkanoate.

[0114] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 10 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 100°C for 1 minute to obtain an anti-penetration paper with a coating dry thickness of 7 μm.

[0115] The viscosity and static stability of the obtained polyhydroxyalkanoate water-based coating were tested, and the heat resistance and corn oil resistance of the obtained waterproof paper were tested. The results are shown in Table 7.

[0116] Table 7

[0117] Test items result Viscosity (mPa.s) 342 Stability at room temperature for 24 hours Unstratified Temperature resistance (℃) 100℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? yes Is it recyclable and degradable? yes Can it be re-pulped? yes

[0118] Example 8

[0119] This embodiment provides a polyhydroxyalkanoate water-based coating, and the preparation method thereof is as follows:

[0120] The fermented bacterial liquid of P34HB is subjected to enzymatic cell wall breaking treatment to obtain an aqueous solution with a P34HB content of 70%, wherein the P34HB particle size is 0.5 micrometers, the melting point is 105°C, and the 4-hydroxybutyric acid content is 25%. 0.5 parts by mass of propylene glycol ether, 0.5 parts by mass of potassium dodecyl phosphate, 0.5 parts by mass of modified polysiloxane and 0.5 parts by mass of polypyrrolidone are added to 100 parts by mass of the aqueous solution, and the mixture is stirred at a speed of 2000 rpm for a dispersion time of 30 minutes to uniformly disperse the additives to form a colloidal uniformly dispersed dilute solution, thereby obtaining a water-based coating of polyhydroxyalkanoate.

[0121] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 10 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 110°C for 1 minute to obtain an anti-penetration paper with a coating dry thickness of 7 μm.

[0122] The viscosity and static stability of the obtained polyhydroxyalkanoate water-based coating were tested, and the heat resistance and corn oil resistance of the obtained waterproof paper were tested. The results are shown in Table 8.

[0123] Table 8

[0124]

[0125]

[0126] Comparative Example 1

[0127] In this comparative example, PHA powder (same as Example 3) was directly dissolved in water to prepare a dispersion system with a dry weight of 35%, and the mixture was stirred at a speed of 2000 rpm for a dispersion time of 30 min to obtain a water-based coating.

[0128] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 15 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 150°C for 1 minute to obtain a composite paper with a coating dry thickness of 6 μm.

[0129] The obtained materials were tested and the results are shown in Table 9.

[0130] This comparative example has no additives added, has poor stability, and is prone to stratification when left standing.

[0131] Table 9

[0132] Test items result Viscosity (mPa.s) 25.4 Stability at room temperature for 24 hours Layering Temperature resistance (℃) 100℃ Corn oil resistance (23℃) 1h penetration Corn oil resistance (100℃) 1h penetration Is the food safe? yes Is it recyclable and degradable? yes Can it be re-pulped? yes

[0133] Comparative Example 2

[0134] In this comparative example, PHA powder (same as Example 3) was directly dissolved in chloroform to prepare a 5% dry weight solution, and the solution was stirred at a speed of 2000 rpm and dispersed for 30 minutes to obtain a coating.

[0135] The coating was applied to the base paper using a wire rod coater, the coating wet material thickness was controlled at 20 μm, and after coating, it was dried at 60° C. for 1 h, and then dried at 150° C. for 1 min to obtain a composite material with a coating dry thickness of 1 μm.

[0136] The obtained materials were tested and the results are shown in Table 10.

[0137] This comparative example uses an organic solvent to prepare the solution, which has low solubility, large amount of organic solvent used, and high pollution.

[0138] Table 10

[0139] Test items result Viscosity (mPa.s) 244 Stability at room temperature for 24 hours No stratification Temperature resistance (℃) 100℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? no Is it recyclable and degradable? yes Can it be re-pulped? yes

[0140] Comparative Example 3

[0141] Weigh 35 parts by mass of P34HB (melting point 165° C., 4-hydroxybutyric acid content 8%) powder (particle size 5 μm), add it to 65 parts by mass of water, use ultrasound for ultrasonic dispersion, and disperse for 30 minutes to evenly disperse the polyhydroxyalkanoate in the water. Then, add 1 part by mass of N-methylpyrrolidone, 1 part by mass of sodium lauroyl acid, 1 part by mass of cellulose and 1 part by mass of corn starch, stir at a speed of 2000 rpm, and disperse for 30 minutes to evenly disperse the additives to form a colloidal, evenly dispersed dilute solution, thereby obtaining a water-based coating of polyhydroxyalkanoate.

[0142] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 15 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 160°C for 1 minute to obtain an anti-penetration paper with a coating dry thickness of 6 μm.

[0143] The obtained materials were tested and the results are shown in Table 11.

[0144] The P34HB used in this comparative example has a high melting point and a high drying and film-forming temperature, which can easily cause the paper to bend, deform and yellow, and the coating is also prone to yellowing.

[0145] Table 11

[0146] Test items result Viscosity (mPa.s) 520 Stability at room temperature for 24 hours Unstratified Temperature resistance (℃) 100℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? yes Is it recyclable and degradable? yes Can it be re-pulped? yes

[0147] Comparative Example 4

[0148] Weigh 35 parts by mass of P34HB (melting point 148° C., 4-hydroxybutyric acid content 18%) powder (particle size 5 μm), add it to 65 parts by mass of water, use ultrasound for ultrasonic dispersion, and disperse for 30 minutes to uniformly disperse the polyhydroxyalkanoate in the water. Then, add 1 part by mass of N-methylpyrrolidone, 1 part by mass of sodium lauroyl acid, 1 part by mass of cellulose and 1 part by mass of corn starch, stir at a speed of 2000 rpm, and disperse for 30 minutes to uniformly disperse the additives to form a colloidal, uniformly dispersed dilute solution, thereby obtaining a water-based coating of polyhydroxyalkanoate.

[0149] The coating was applied to the base paper using a wire rod coater, the wet coating thickness was controlled at 15 μm, and after coating, it was dried at 60°C for 1 hour and then dried at 160°C for 1 minute to obtain an anti-penetration paper with a coating dry thickness of 6 μm.

[0150] The obtained material was tested and the results are shown in Table 12.

[0151] The P34HB used in this comparative example has a high melting point and a high drying and film-forming temperature, which can easily cause the paper to bend, deform and yellow, and the coating is also prone to yellowing.

[0152] Table 12

[0153] Test items result Viscosity (mPa.s) 380 Stability at room temperature for 24 hours Unstratified Temperature resistance (℃) 100℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? yes Is it recyclable and degradable? yes Can it be re-pulped? yes

[0154] Comparative Example 4

[0155] This comparative example adopts a PE coating layer composite paper layer.

[0156] The obtained material was tested and the results are shown in Table 13.

[0157] This comparative example uses PE coating, which is non-degradable and has high investment cost for separating the coating layer from the paper layer.

[0158] Table 13

[0159] Test items result Viscosity (mPa.s) / Stability at room temperature for 24 hours / Temperature resistance (℃) 80℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? yes Is it recyclable and degradable? no Can it be re-pulped? no

[0160] Comparative Example 5

[0161] This comparative example uses a PLA coating layer and a composite paper layer.

[0162] The obtained materials were tested and the results are shown in Table 14.

[0163] This comparative example uses PLA coating, which needs composting to degrade, which is costly, and the coating composite material cannot be directly re-pulped and reused.

[0164] Table 14

[0165] Test items result Viscosity (mPa.s) / Stability at room temperature for 24 hours / Temperature resistance (℃) 60℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? yes Is it recyclable and degradable? yes Can it be re-pulped? no

[0166] Comparative Example 6

[0167] This comparative example uses acrylic acid water-based paint to composite the paper layer.

[0168] The obtained material was tested and the results are shown in Table 15.

[0169] This comparative example uses acrylic water-based coating. Although it can be re-pulped, acrylic acid cannot be degraded and produces microplastic hazards.

[0170] Table 15

[0171] Test items result Viscosity (mPa.s) 423 Stability at room temperature for 24 hours No stratification Temperature resistance (℃) 60℃ Corn oil resistance (23℃) 1h no penetration Corn oil resistance (100℃) 1h no penetration Is the food safe? yes Is it recyclable and degradable? no Can it be re-pulped? yes

[0172] It can be seen from the above results that the polyhydroxyalkanoate water-based coatings prepared in Examples 1-8 of the present invention have good system stability, good oil and water resistance, can be degraded in the natural environment, and can be directly re-pulped and reused without pollution. In addition, the present invention has low cost, simple production process, and is easy to industrialize.

[0173] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polyhydroxyalkanoate water-based coating, characterized in that: Includes polyhydroxyalkanoate suspension and adjuvant; The melting point of the polyhydroxyalkanoate is 100-120° C., and the polyhydroxyalkanoate comprises a copolymer of at least two polymerizable monomers.

2. The polyhydroxyalkanoate water-based coating according to claim 1, characterized in that: When the polymerized monomer includes 4HB, the monomer content of 4HB is 21%-30%; and / or, when the polymerized monomer includes 3HV, the monomer content of 3HV is 5%-20%; And / or, when the polymerized monomer includes 5HV, the monomer content of 5HV is 5%-20%.

3. The polyhydroxyalkanoate water-based coating according to claim 1 or 2, characterized in that: The polyhydroxyalkanoate comprises a copolymer of two polymerized monomers; Preferably, the copolymer of the two polymerizable monomers is selected from one or more of P34HB, PHBV, PHBHHx, PHBHO, and PHBHN.

4. The polyhydroxyalkanoate water-based coating according to claim 1 or 2, characterized in that: The polyhydroxyalkanoate comprises a copolymer of three polymerized monomers; Preferably, the copolymer of the three polymerized monomers is selected from one or more of P3HB4HB3HV and P3HB4HB5HV.

5. The polyhydroxyalkanoate water-based coating according to any one of claims 1 to 4, characterized in that: The polyhydroxyalkanoate water-based coating is suitable for processing paper with a tolerance temperature of more than the melting point of the polyhydroxyalkanoate and less than 150°C.

6. The polyhydroxyalkanoate water-based coating according to any one of claims 1 to 4, characterized in that: The polyhydroxyalkanoate suspension is obtained by dispersing PHA powder into water; Alternatively, the polyhydroxyalkanoate suspension is obtained by centrifugation extraction of PHA fermentation broth.

7. The polyhydroxyalkanoate water-based coating according to claim 6, characterized in that: In the polyhydroxyalkanoate suspension, the mass fraction of polyhydroxyalkanoate is 30-70%, and the added amount of the auxiliary agent does not exceed 5% of the mass of the polyhydroxyalkanoate suspension.

8. The polyhydroxyalkanoate water-based coating according to claim 7, characterized in that: The auxiliary agent includes one or more of a film former, a wetting agent, a leveling agent, and a thickener; Preferably, based on the mass of the polyhydroxyalkanoate suspension, the added amount of the film former is 0.1-1%, the added amount of the wetting agent is 0.1-1%, the added amount of the leveling agent is 0.1-1%, and the added amount of the thickener is 0.1-1%; Further preferably, the film-forming agent is selected from one or more of diethanol ether, propylene glycol ether, and N-methylpyrrolidone; And / or, the wetting agent is selected from one or more of alkyl nonylphenol ethoxylate, potassium dodecyl phosphate, sodium dodecyl polyoxyethylene ether sulfate, sodium lauroyl acid, sodium α-olefin sulfonate; And / or, the leveling agent is selected from one or more of Digo 432, modified polysiloxane, and cellulose; And / or, the thickener is selected from one or more of gelatinized starch, polyacrylonitrile, sodium dodecylbenzene sulfonate, sodium polyacrylate, sodium alginate, and polypyrrolidone; preferably, the gelatinized starch is selected from one or more of corn starch, potato starch, sweet potato starch, and cassava starch.

9. The method for preparing the polyhydroxyalkanoate water-based coating according to any one of claims 1 to 8, characterized in that: include: The auxiliary agent is dispersed in the polyhydroxyalkanoate suspension to form a colloidal dispersion solution.

10. Use of the polyhydroxyalkanoate water-based coating according to any one of claims 1 to 8 in the preparation of anti-penetration materials.

11. An anti-permeation paper, characterized in that: The invention comprises paper and a coating applied on the paper, wherein the coating is made of the polyhydroxyalkanoate water-based coating according to any one of claims 1 to 8; and the paper is preferably white cardboard.

12. The anti-permeation paper according to claim 11, characterized in that: The thickness of the coating is 3-14 microns; Preferably, the method for preparing the anti-permeation paper comprises: applying the polyhydroxyalkanoate water-based coating on paper, controlling the coating wet material thickness to 10-20 microns, drying at 60-65°C for 1-1.5h after coating, and then drying at 120-150°C for no more than 1min, to obtain an anti-permeation paper with a coating dry thickness of 3-14 microns.

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