Aqueous polyhydroxyalkanoate coating, preparation method therefor and use thereof

Abstract

The present invention provides an aqueous polyhydroxyalkanoate coating, a preparation method therefor, and a use thereof. The preparation method for the aqueous polyhydroxyalkanoate coating comprises: subjecting a polyhydroxyalkanoate fermentation solution to cell wall breaking and extraction, to obtain an aqueous polyhydroxyalkanoate dispersion, and then mixing the aqueous polyhydroxyalkanoate dispersion with an additive to obtain the aqueous polyhydroxyalkanoate coating, a dispersant and talcum powder being added during the cell disruption process. By means of using talcum powder to replace a portion of a dispersant as a protective additive for PHA particles, the present invention can prevent the aggregation of PHA particles at high purity, and the resulting aqueous PHA coating exhibits good coating water resistance.

Description

Polyhydroxyaliphatic acid ester aqueous coating and preparation method and application thereof

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 2024105875520 entitled "Polyhydroxyaliphatic acid ester aqueous coating and preparation method and application thereof" filed on May 13, 2024, the entire disclosure of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the field of aqueous coatings, in particular to a polyhydroxyaliphatic acid ester aqueous coating and preparation method and application thereof. BACKGROUND

[0004] With the enhancement of people's environmental awareness, PHA (polyhydroxyaliphatic acid ester) is applied more and more widely as a degradable material. It has become a hot topic in the industry to apply PHA as a film-forming material in the aqueous coating industry.

[0005] One of the current preparation methods of PHA aqueous coating is to obtain PHA aqueous dispersion by breaking the wall of PHA fermentation broth, and then adding a small amount of bactericide, thickening agent and other additives to configure. During the breaking process, the purity of PHA particles will increase with the increase of the breaking degree, and the PHA particles will appear agglomeration phenomenon. To prevent the occurrence of agglomeration phenomenon, the method that is easy to think of at present is to add polyacrylic acid sodium salt and other commonly used dispersants in the coating industry during the breaking process of PHA fermentation broth. The addition of dispersants can prevent the occurrence of agglomeration phenomenon, but because the dispersants are usually water-soluble, it will cause the water resistance of the coating film to decrease.

[0006] Therefore, it is desirable to provide a PHA aqueous coating, which PHA particles do not agglomerate at high purity and have good coating film water resistance. SUMMARY

[0007] In view of the problems existing in the prior art, the present application provides a polyhydroxyaliphatic acid ester aqueous coating and preparation method and application thereof.

[0008] In a first aspect, the present application provides a preparation method of a polyhydroxyaliphatic acid ester aqueous coating, comprising: obtaining a polyhydroxyaliphatic acid ester aqueous dispersion by breaking the wall of a polyhydroxyaliphatic acid ester fermentation broth, and then mixing the polyhydroxyaliphatic acid ester aqueous dispersion with additives to obtain the polyhydroxyaliphatic acid ester aqueous coating.

[0009] In the breaking process, a dispersant and talc are added.

[0010] Talcum powder is generally used as a filler in the paint industry, and its main role is to improve hardness and reduce cost. It is accidentally found in the present application that the talcum powder can replace part of the dispersant and be used as a protective aid for PHA particles, so that the PHA particles do not agglomerate at high purity, and the PHA water-based paint prepared has good water resistance of the coating film. The talcum powder used in the present application is ultra-fine talcum powder (mesh number 2500 or more) or nano talcum powder (10000 or more), and the larger the mesh number, the better.

[0011] The flaky structure of the talcum powder in the present application forms a stable barrier layer on the outside of the PHA particles, effectively preventing the agglomeration of the PHA particles, and the talcum powder is not soluble in water, so the coating film has good water resistance. The inventors have also tried to use talcum powder as a protective aid without adding a general dispersant, which should theoretically have good water resistance of the coating film, but in practice it is not the case. The reason is that the talcum powder itself is an inorganic substance, and without a dispersant, it is difficult to disperse completely and cannot effectively coat the PHA particles. The particle agglomeration forms large particles, affecting the water resistance. Therefore, the talcum powder can replace part of the dispersant, and the two can work together. The shortcomings of the single dispersant, such as poor water resistance, and the shortcomings of the single talcum powder, such as poor coating and easy agglomeration of PHA particles, are overcome. The PHA water-based paint prepared in this way does not agglomerate, and has good water resistance of the coating film.

[0012] The polyhydroxyalkanoate fermentation broth in the present application refers to the fermentation broth obtained after fermentation of microorganisms capable of synthesizing PHA. According to the number of carbon atoms in the monomer, PHA can be divided into short-chain PHA (composed of monomers with 3 to 5 carbon atoms) and medium-chain PHA (composed of monomers with 6 to 14 carbon atoms); in addition, according to the different arrangement of monomers, PHA can also be divided into homopolymer, random copolymer and block copolymer. Specifically, the PHA can be one or more of PHB, P34HB, PHBV, PHBHHx, PHBHO, PHBHN, P3HB4HB3HV, P3HB4HB5HV. By optimizing the fermentation conditions and strain improvement, the production efficiency of PHA can be effectively improved and the cost can be reduced. This can refer to the prior art, which is not the focus of the present application, and will not be described here.

[0013] In the present application, the specific breaking wall extraction method can be a physical method, a chemical method, a biological method or a combination thereof. In some embodiments of the present application, one or more of enzymatic hydrolysis, chemical reagent method, high pressure homogenization, grinding and ultrasonic treatment is selected.

[0014] Among them, enzymatic hydrolysis uses specific cell wall degrading enzymes (such as lysozyme) to decompose the cell wall, which has less damage to PHA and is beneficial to maintain the quality and performance of PHA.

[0015] Chemical reagents are chemical reagents such as surfactants, organic solvents, or acids and bases that destroy the cell wall. For example, the cell is treated with an alkaline solution such as sodium hypochlorite or sodium hydroxide.

[0016] High pressure homogenization is a method in which a high pressure homogenizer is used to apply high pressure, and the cell is broken by the shear force and pressure when passing through a narrow gap.

[0017] Grinding is a method in which a device such as a sand mill or a bead mill is used to break the cell wall by mechanical grinding.

[0018] Ultrasonic treatment is a method in which ultrasonic waves are used to break the cell, and it is a highly efficient physical method of breaking the cell wall that can break the cell wall in a short time.

[0019] In the preferred embodiments of the present application, enzymatic hydrolysis and / or high pressure homogenization are used for the wall-breaking extraction. Further, in the applicant's prior application, it is preferred to use a complex enzyme preparation for enzymatic hydrolysis, which includes lysozyme, nucleic acid-degrading enzyme, dextranase, mannanase, snail enzyme, and protease.

[0020] It can be understood that in the above technical solution, before the polyhydroxyalkanoate fermentation broth is subjected to wall-breaking extraction, the bacterial cells and impurities in the fermentation broth are preferably removed by centrifugation or filtration to obtain a cell precipitate containing polyhydroxyalkanoate.

[0021] After the wall-breaking extraction is completed, purification treatment is preferably performed to remove impurities such as cell debris, proteins, polysaccharides, and lipids, thereby obtaining a polyhydroxyalkanoate aqueous dispersion. In some embodiments of the present application, multiple centrifugal washing steps are used for purification, which is economical and simple.

[0022] Preferably, the total mass of the dispersant and the talc before addition is 2-10% of the mass of the fermentation broth, and the mass ratio of the dispersant to the talc is 1:5-5:1, and further preferably 2:3-3:2.

[0023] In some embodiments of the present application, the dispersant is selected from one or more of sodium hexametaphosphate, polyacrylic acid sodium salt, styrene maleic anhydride sodium salt, styrene maleic anhydride ammonium salt, polysorbate, sodium oleate, and sodium ethyl sulfate.

[0024] Further preferably, the adding timing of the dispersant and the talc is subject to the condition that the release amount of the polyhydroxyaliphatic acid ester is not more than 60% of the total release amount. The total release amount refers to the total amount of the polyhydroxyaliphatic acid ester released after the completion of the wall breaking. During the reaction, the specific release amount can be quantitatively analyzed by weight, ultraviolet absorption spectrum or other chemical analysis methods. It can be understood that the dispersant and the talc can also be added before the start of the wall breaking. However, if the dispersant and the talc are added after the completion of the wall breaking, the improvement of the agglomeration effect is obviously poor.

[0025] In the present application, the solid content of the polyhydroxyaliphatic acid ester aqueous dispersion is preferably adjusted to be between 30-55% before mixing with the auxiliary agent.

[0026] Adjusting the solid content of the polyhydroxyaliphatic acid ester aqueous dispersion to the above range can on the one hand obtain the ideal viscosity, and on the other hand is beneficial to the formation of the coating film during subsequent coating. If the solid content is too low, the water in the coating film can not be completely evaporated after passing through the drying tunnel, affecting the formation of the coating film.

[0027] Further, the auxiliary agent in the present application includes one or more of bactericides, wetting agents, thickening agents, leveling agents, and defoaming agents.

[0028] Preferably, the amount of each auxiliary agent added is 0.01-0.5% based on the mass of the polyhydroxyaliphatic acid ester aqueous dispersion after adjusting the solid content.

[0029] In some embodiments of the present application, the bactericide is selected from one or more of ethylenediaminetetraacetic acid, benzisothiazolinone, zinc oxide, benzalkonium chloride, methylisothiazolinone, methylchloroisothiazolinone, and 2,2-dibromopropionamide.

[0030] In some embodiments of the present application, the wetting agent is selected from one or more of nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, and polysiloxane.

[0031] In some embodiments of the present application, the thickening agent is selected from one or more of nanocellulose, alkali-swellable acrylic thickening agent, xanthan gum, hydroxypropyl cellulose, and sodium alginate.

[0032] In some embodiments of the present application, the leveling agent is selected from one or more of polyether siloxane copolymer, modified polysiloxane, and polyurethane rheology modifier.

[0033] In some embodiments of the present application, the defoaming agent is selected from one or more of silicone-based, mineral oil-based, and silicone-modified mineral oil.

[0034] Further, the mixing of the above-mentioned auxiliary agent and the polyhydroxyaliphatic acid ester aqueous dispersion can adopt the commonly used mixing methods in the field, such as mechanical stirring or ultrasonic dispersion.

[0035] In some embodiments of the present application, after obtaining the polyhydroxyalkanoate aqueous dispersion with the target solid content, the polyhydroxyalkanoate aqueous dispersion and each additive are weighed according to the mass ratio, and are dispersed at a high speed of 1000-2000 r / min for 10-30 minutes to adjust the viscosity to 200-1000 mPa.s.

[0036] In a second aspect, the present application provides an aqueous coating material, comprising polyhydroxyalkanoate, and further comprising talc and a dispersant which can be used to improve the dispersibility of the suspended particles of polyhydroxyalkanoate.

[0037] Further, the dispersant is selected from one or more of sodium hexametaphosphate, sodium polyacrylate, styrene maleic anhydride sodium salt, styrene maleic anhydride ammonium salt, polysorbate, sodium oleate, and sodium ethyl sulfate.

[0038] Further, the mass ratio of the dispersant to the talc is 1:5-5:1, preferably 2:3-3:2.

[0039] Preferably, the aqueous coating material of the present application comprises the polyhydroxyalkanoate aqueous coating material prepared by the above preparation method.

[0040] Preferably, the viscosity of the polyhydroxyalkanoate aqueous coating material is 200-1000 mPa.s.

[0041] In some embodiments of the present application, the polyhydroxyalkanoate in the polyhydroxyalkanoate aqueous coating material comprises one or more of PHB, P34HB, PHBV, PHBHHx, PHBHO, PHBHN, P3HB4HB3HV, and P3HB4HB5HV.

[0042] When the polymerized monomers are multiple monomers, the molar ratio of each monomer can be determined according to actual conditions. For example, for P34HB, the 4HB molar content suitable for coating applications is any value in the range of 10%-20%, such as 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%. When the 4HB content is less than 10%, film formation is difficult, and when the 4HB content is greater than 20%, the film is too soft and tends to stick.

[0043] In a third aspect, the present application provides a water-resistant coating film obtained by applying the above aqueous coating material to the surface of a substrate.

[0044] The substrate is selected from a plastic substrate, a metal substrate, a paper substrate, a ceramic substrate, or a glass substrate, and is preferably a paper substrate.

[0045] Specifically, since the polyhydroxyaliphatic ester water-based paint has good dispersibility and suitable fluidity, the water-based paint can be coated onto the surface of a substrate by using conventional methods such as a doctor blade, a wire bar, an air knife, and spraying, and then subjected to a drying treatment at a drying temperature of 110-180 ℃ and a drying time of 10-60 s.

[0046] The substrate is a planar substrate or a non-planar substrate. The planar substrate is, for example, paper, a wood board, or the like, and the non-planar substrate is, for example, the surface of a formed paper cup or the like. The film thickness can be adjusted according to actual needs.

[0047] The polyhydroxyaliphatic ester water-based paint, the preparation method and the application thereof provided by the present application can play a synergistic effect by replacing part of the dispersant with talc powder, overcome the shortcomings of poor water resistance of the dispersant alone and poor coating of the talc powder alone and easy aggregation of PHA particles, and thus the PHA water-based paint prepared by the method does not have particle aggregation and has good film water resistance. Moreover, the production process is simple, and the application prospect is wide. DETAILED DESCRIPTION

[0048] The term "comprising" or "including" in the present application is an open description, which contains the specified components or steps described, and other specified components or steps that do not substantially affect.

[0049] The endpoints of the ranges and any values in the ranges disclosed herein are not limited to the precise values stated. The ranges and values should be construed to be approximations that allow for significant variation. Various ranges of values are stated in terms of being between two specific values. When values are provided in a range, the values in the range are intended to be the same as if each value from the range is individually listed herein. For example, a range from 1 to 6 should be interpreted to include not only the specifically recited values of 1, 2, 3, 4, 5, and 6, but also each value and sub-range between the minimum value of 1 and the maximum value of 6, i.e., a range of values from the lower endpoint to the upper endpoint, 1, 0.9, 0.8, 0.7, 0.6, etc., through 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, etc., and 6.7, 6.8, 6.9, 7, etc. The same applies to ranges of values from the lower endpoint to the upper endpoint, 6, 6.9, 6.8, 6.7, etc., through 6, 6.5, 6.4, 6.3, etc., and 6.2, 6.1, 6, etc. In another example, a range from 1 to 6 should be interpreted to include not only the specifically recited values of 1, 2, 3, 4, 5, and 6, but also each value and sub-range between the minimum value of 1 and the maximum value of 6, i.e., a range of values from the lower endpoint to the upper endpoint, 1, 0.9, 0.8, 0.7, 0.6, etc., through 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, etc., and 6.7, 6.8, 6.9, 7, etc. The same applies to ranges of values from the lower endpoint to the upper endpoint, 6, 6.9, 6.8, 6.7, etc., through 6, 6.5, 6.4, 6.3, etc., and 6.2, 6.1, 6, etc.

[0050] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", or "some specific embodiments" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0051] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0052] Unless otherwise specified in the embodiments, the techniques or conditions are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Unless otherwise specified, the reagents or instruments used are conventional products that can be purchased through a regular channel.

[0053] The English abbreviations appearing in the present application correspond to the following Chinese full names: PHA: polyhydroxyalkanoate PHBV: poly(3-hydroxybutyrate-co-3-hydroxyvalerate) P34HB: poly(3-hydroxybutyrate-co-4-hydroxybutyrate) PHBHHx: poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) PHBHO: poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) PHBHN: poly(3-hydroxybutyrate-co-3-hydroxynonanoate) P3HB4HB3HV: poly(3-hydroxybutyrate-co-4-hydroxybutyrate-co-3-hydroxyvalerate) P3HB4HB5HV: poly(3-hydroxybutyrate-co-4-hydroxybutyrate-co-5-hydroxyvalerate).

[0054] The parts in the following examples are parts by weight, unless otherwise specified.

[0055] The talc used in the following examples is talc with a mesh size of 2500 mesh or more; and the base material used is a paper base material.

[0056] Example 1

[0057] The aqueous coating provided in this example has the following composition:

[0058] The PHB aqueous dispersion (55% solid content) is 100 parts, the benzisothiazolinone is 0.2 parts, the alkali-swelling acrylic thickening agent is 0.5 parts, and the silicone defoaming agent is 0.01 parts.

[0059] The preparation method is as follows:

[0060] PHB aqueous dispersion preparation: The PHB fermentation broth is centrifuged and washed, 1% polyacrylic acid sodium salt and 1% talc are added, and homogenization is performed three times at a pressure of 1200 bar, and centrifugal washing is performed three times at 12000 r / min, and the solid content is adjusted to 55%.

[0061] Waterborne paint configuration steps: according to the mass ratio of each component, 2000r / min high speed dispersion 10min, adjust the viscosity to 1000mPa.s.

[0062] The use method of the waterborne paint obtained in the embodiment is as follows:

[0063] The scraper, wire rod, air knife, spraying and other methods are used to coat the surface of the substrate, and then drying treatment is carried out, the drying temperature is 180℃, and the drying time is 10s.

[0064] Example 2

[0065] The embodiment provides a waterborne paint, which comprises the following components:

[0066] P34HB waterborne dispersion (40% solid content) 100 parts, benzalkonium chloride 0.2 parts, hydroxypropyl cellulose 0.5 parts, polyether siloxane copolymer 0.2 parts and silicone modified mineral oil 0.01 parts.

[0067] The preparation method is as follows:

[0068] P34HB waterborne dispersion preparation: the P34HB fermentation liquor is centrifuged and washed, after preliminary enzymolysis to about 50% of the total release amount of P34HB, 3% polyacrylic acid sodium salt and 3% talc are added, 1000bar pressure homogenization is adopted for 4 times, and 8000r / min centrifugal washing is carried out for 4 times, and the solid content is adjusted to 40%.

[0069] Waterborne paint configuration steps: according to the mass ratio of each component, 1500r / min high speed dispersion 20min, adjust the viscosity to 600mPa.s.

[0070] The use method of the waterborne paint obtained in the embodiment is as follows:

[0071] The scraper, wire rod, air knife, spraying and other methods are used to coat the surface of the substrate, and then drying treatment is carried out, the drying temperature is 150℃, and the drying time is 30s.

[0072] Example 3

[0073] The embodiment provides a waterborne paint, which comprises the following components:

[0074] PHBV waterborne dispersion (50% solid content) 100 parts, methyl chloroisothiazolinone 0.3 parts, octylphenol polyoxyethylene ether 0.1 parts, xanthan gum 0.5 parts and silicone modified mineral oil defoaming agent 0.02 parts.

[0075] The preparation method is as follows:

[0076] PHBV aqueous dispersion preparation: PHBV fermentation broth was centrifuged and washed, and after primary enzymolysis to a PHBV release amount of about 40% of the total release amount, 5% polyacrylic acid sodium salt and 5% talc were added, and homogenization was performed 5 times at a pressure of 600 bar, and centrifugal washing was performed 5 times, and the solid content was adjusted to 50%.

[0077] Water-based paint configuration step: each component was weighed according to the mass ratio, and high-speed dispersion was performed at 1200 r / min for 30 min, and the viscosity was adjusted to 700 mPa.s.

[0078] The use method of the water-based paint obtained in this example is as follows:

[0079] The scraper, wire bar, air knife, spraying and the like were used to apply to the surface of the substrate, and then drying treatment was performed, the drying temperature was 160°C, and the drying time was 20 s.

[0080] Example 4

[0081] This example provides a water-based paint, which has the following composition:

[0082] PHBHHx aqueous dispersion (35% solid content) 100 parts, zinc oxide 0.8 parts, nonylphenol polyoxyethylene ether 0.1 part, and alkali-swollen acrylic thickening agent 0.4 part.

[0083] The preparation method is as follows:

[0084] PHBHHx aqueous dispersion preparation: PHBHHx fermentation broth was centrifuged and washed, and after primary enzymolysis to a PHBHHx release amount of about 30% of the total release amount, 2% polyacrylic acid sodium salt and 3% talc were added, and homogenization was performed 5 times at a pressure of 500 bar, and centrifugal washing was performed 5 times at 6000 r / min, and the solid content was adjusted to 35%.

[0085] Water-based paint configuration step: each component was weighed according to the mass ratio, and high-speed dispersion was performed at 1000 r / min for 30 min, and the viscosity was adjusted to 500 mPa.s.

[0086] The use method of the water-based paint obtained in this example is as follows:

[0087] The scraper, wire bar, air knife, spraying and the like were used to apply to the surface of the substrate, and then drying treatment was performed, the drying temperature was 140°C, and the drying time was 50 s.

[0088] Example 5

[0089] This example provides a water-based paint, which has the following composition:

[0090] P3HB4HB3HV aqueous dispersion (30% solid content) 100 parts, methylisothiazolinone 0.2 parts, alkali-swollen acrylic thickening agent 0.5 parts, and mineral oil defoaming agent 0.01 part.

[0091] The preparation method is as follows:

[0092] Preparation of P3HB4HB3HV aqueous dispersion: The P3HB4HB3HV fermentation liquor is centrifuged and washed, and after preliminary enzymolysis to a P3HB4HB3HV release amount of about 20% of the total release amount, 3% of sodium polyacrylate and 2% of talcum powder are added, 700 bar pressure homogenization is performed 5 times, and 5000 r / min centrifugal washing is performed 5 times to adjust the solid content to 30%.

[0093] Water-based paint configuration step: each component is weighed according to the mass ratio, high-speed dispersion is performed at 1200 r / min for 30 min, and the viscosity is adjusted to 200 mPa.s.

[0094] The use method of the water-based paint obtained in this example is as follows:

[0095] The scraper, wire bar, air knife, spraying and the like are used to apply to the surface of the substrate, and then drying treatment is performed, the drying temperature is 110°C, and the drying time is 60s.

[0096] Example 6

[0097] This example provides a water-based paint, which has the following composition:

[0098] P34HB aqueous dispersion (40% solid content) 100 parts, benzalkonium chloride 0.2 parts, hydroxypropyl cellulose 0.5 parts, polyether siloxane copolymer 0.2 parts and silicone modified mineral oil 0.01 parts.

[0099] The preparation method is as follows:

[0100] Preparation of P34HB aqueous dispersion: The P34HB fermentation liquor is centrifuged and washed, and after preliminary enzymolysis to a P34HB release amount of 60% of the total release amount, 1% of styrene maleic anhydride ammonium salt and 5% of talcum powder are added, 1000 bar pressure homogenization is performed 4 times, and 8000 r / min centrifugal washing is performed 4 times to adjust the solid content to 40%.

[0101] Water-based paint configuration step: each component is weighed according to the mass ratio, high-speed dispersion is performed at 1500 r / min for 20 min, and the viscosity is adjusted to 600 mPa.s.

[0102] The use method of the water-based paint obtained in this example is as follows:

[0103] The scraper, wire bar, air knife, spraying and the like are used to apply to the surface of the substrate, and then drying treatment is performed, the drying temperature is 150°C, and the drying time is 30s.

[0104] Example 7

[0105] This example provides a water-based paint, which has the following composition:

[0106] PHBV aqueous dispersion (50% solid content) 100 parts, methyl chloroisothiazolinone 0.3 parts, octylphenol polyoxyethylene ether 0.1 parts, xanthan gum 0.5 parts and silicone modified mineral oil defoamer 0.02 parts.

[0107] The preparation method is as follows:

[0108] PHBV aqueous dispersion preparation: PHBV fermentation broth is centrifuged and washed, and is subjected to preliminary enzymolysis until the PHBV release amount is 10% of the total release amount, 5% polysorbate and 1% talc are added, 5 times of homogenization at 600 bar pressure are adopted, and 5 times of centrifugal washing are adopted to adjust the solid content to 50%.

[0109] Water-based paint configuration steps: each component is weighed according to the mass ratio, high-speed dispersion is carried out for 30 min, and the viscosity is adjusted to 700 mPa.s.

[0110] The use method of the water-based paint obtained in the example is as follows:

[0111] The scraper, wire bar, air knife, spraying and the like are used to apply to the surface of the substrate, and then drying treatment is carried out, the drying temperature is 160°C, and the drying time is 20 s.

[0112] Comparative Example 1

[0113] The comparative example provides a water-based paint, which comprises the following components:

[0114] PHB aqueous dispersion (55% solid content) 100 parts, benzisothiazolinone 0.2 parts, alkali-swelling acrylic thickening agent 0.5 parts and silicone defoamer 0.01 parts.

[0115] The preparation method is as follows:

[0116] PHB aqueous dispersion preparation: PHB fermentation broth is centrifuged and washed, 2% polyacrylic acid sodium salt is added, 3 times of homogenization at 1200 bar pressure are adopted, 3 times of centrifugal washing at 12000 r / min are adopted, and the solid content is adjusted to 55%.

[0117] Water-based paint configuration steps: each component is weighed according to the mass ratio, high-speed dispersion is carried out for 10 min, and the viscosity is adjusted to 1000 mPa.s.

[0118] The use method is as follows:

[0119] The scraper, wire bar, air knife, spraying and the like are used to apply to the surface of the substrate, and then drying treatment is carried out, the drying temperature is 180°C, and the drying time is 10 s.

[0120] Comparative Example 2

[0121] The comparative example provides a water-based paint, which comprises the following components:

[0122] PHB aqueous dispersion (55% solid content) 100 parts, benzisothiazolinone 0.2 parts, alkali-swelling acrylic thickener 0.5 parts, and silicone defoaming agent 0.01 parts.

[0123] The preparation method is as follows:

[0124] PHB aqueous dispersion preparation: the PHB fermentation broth is centrifuged and washed, 2% talcum powder is added, homogenized for 3 times at a pressure of 1200 bar, and centrifuged for 3 times at 12000 r / min to adjust the solid content to 55%.

[0125] Water-based paint configuration steps: weigh each component according to the mass ratio, high-speed dispersion for 10 min, and adjust the viscosity to 1000 mPa.s.

[0126] The use method is as follows:

[0127] Use a scraper, wire bar, air knife, spraying and other methods to apply to the surface of the substrate, and then perform drying treatment, drying temperature 180°C, drying time 10s.

[0128] Comparative Example 3

[0129] This comparative example provides a water-based paint, which is composed of:

[0130] P3HB4HB3HV aqueous dispersion (30% solid content) 100 parts, methylisothiazolinone 0.2 parts, alkali-swelling acrylic thickener 0.5 parts, and mineral oil defoaming agent 0.01 parts.

[0131] The preparation method is as follows:

[0132] P3HB4HB3HV aqueous dispersion preparation: the P3HB4HB3HV fermentation broth is centrifuged and washed, 5% polyacrylic acid sodium salt is added after preliminary enzymatic hydrolysis to release about 20% of the total release amount of P3HB4HB3HV, homogenized for 5 times at a pressure of 700 bar, and centrifuged for 5 times at 5000 r / min to adjust the solid content to 30%.

[0133] Water-based paint configuration steps: weigh each component according to the mass ratio, high-speed dispersion for 30 min at 1200 r / min, and adjust the viscosity to 200 mPa.s.

[0134] The use method is as follows:

[0135] Use a scraper, wire bar, air knife, spraying and other methods to apply to the surface of the substrate, and then perform drying treatment, drying temperature 110°C, drying time 60s.

[0136] Comparative Example 4

[0137] The comparative example provides a water-based paint, which has the following composition:

[0138] P3HB4HB3HV water-based dispersion (30% solid content) 100 parts, methyl isothiazolinone 0.2 parts, alkali-swelling acrylic thickener 0.5 parts, mineral oil defoaming agent 0.01 parts.

[0139] The preparation method is as follows:

[0140] Preparation of P3HB4HB3HV water-based dispersion: The P3HB4HB3HV fermentation broth is centrifuged and washed, and after preliminary enzymolysis to a P3HB4HB3HV release amount of about 20% of the total release amount, 5% talc powder is added, and homogenization is performed 5 times at a pressure of 700 bar, and centrifugal washing is performed 5 times at 5000 r / min, and the solid content is adjusted to 30%.

[0141] Water-based paint configuration steps: weigh each component according to the mass ratio, high-speed dispersion at 1200 r / min for 30 min, and adjust the viscosity to 200 mPa.s.

[0142] The use method is as follows:

[0143] Use a scraper, wire bar, air knife, spraying and other methods to apply to the surface of the substrate, and then perform drying treatment, the drying temperature is 110°C, and the drying time is 60s.

[0144] Comparative example 5

[0145] The comparative example provides a water-based paint, which has the following composition:

[0146] P3HB4HB3HV water-based dispersion (30% solid content) 100 parts, methyl isothiazolinone 0.2 parts, alkali-swelling acrylic thickener 0.5 parts, and mineral oil defoaming agent 0.01 parts.

[0147] The preparation method is as follows:

[0148] Preparation of P3HB4HB3HV water-based dispersion: The P3HB4HB3HV fermentation broth is centrifuged and washed, and after preliminary enzymolysis to a P3HB4HB3HV release amount of about 20% of the total release amount, 5% talc powder is added, and homogenization is performed 5 times at a pressure of 700 bar, and centrifugal washing is performed 5 times at 5000 r / min, and the solid content is adjusted to 30%.

[0149] Water-based paint configuration steps: weigh each component according to the mass ratio, high-speed dispersion at 1200 r / min for 30 min, and adjust the viscosity to 200 mPa.s.

[0150] The use method of the water-based paint obtained in the comparative example is as follows:

[0151] The coating is applied to the surface of the substrate by means of a doctor blade, a wire bar, an air knife, spraying, etc., and then dried at a temperature of 110 DEG C for 60 seconds.

[0152] Performance characterization

[0153] The water-based paint obtained in each example and comparative example is detected, and the results are shown in Table 1.

[0154] The paint fineness is measured by a doctor blade fineness meter, and the fineness can more quickly and intuitively indicate whether the agglomeration phenomenon occurs in the paint system, and the higher the fineness, the more serious the agglomeration phenomenon.

[0155] Table 1

[0156] From the above results, it can be seen that the present application can play a synergistic effect by replacing part of the dispersant with talc powder, which not only overcomes the poor water resistance of the dispersant itself, but also overcomes the poor coating of talc powder and the easy agglomeration of PHA particles. The PHA water-based paint prepared in this way does not have particle agglomeration phenomenon and has good coating film water resistance. Moreover, the production process of the present application is simple and has a broad application prospect.

[0157] The results of Comparative Example 1 and Comparative Example 3 show that the use of only organic dispersant can prevent particle flocculation, but can cause poor water resistance (the dispersant itself is soluble in water). The results of Comparative Example 2 and Comparative Example 4 show that the use of only talc powder cannot prevent PHA particle agglomeration, and the agglomeration phenomenon also causes poor water resistance (leakage in film formation, incomplete). The results of Comparative Example 5 show that the timing of adding the dispersant and talc powder is very important, and after the particle is deeply broken, the particle has already agglomerated and cannot play its due role.

[0158] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present application. Industrial applicability

[0159] The application provides a polyhydroxyalkanoate water-based paint, a preparation method and application thereof, and the preparation method of the polyhydroxyalkanoate water-based paint comprises the following steps: obtaining a polyhydroxyalkanoate water-based dispersion by breaking the wall of a polyhydroxyalkanoate fermentation liquor, and then mixing the polyhydroxyalkanoate water-based dispersion with an additive to obtain the polyhydroxyalkanoate water-based paint; wherein, a dispersing agent and talc are added in the process of breaking the wall. In the application, the talc is used to replace part of the dispersing agent and acts as a protective additive for PHA particles, so that the PHA particles do not agglomerate under high purity, and the prepared PHA water-based paint has good water resistance of a coating film, and has good economic value and application prospect.

Claims

1. A method for preparing a polyhydroxyalkanoate aqueous coating, characterized by, The application relates to a polyhydroxyalkanoate water-based coating, which comprises the following steps: The polyhydroxyalkanoate fermentation liquor is extracted by cell wall breaking to obtain a polyhydroxyalkanoate water-based dispersion, and then the polyhydroxyalkanoate water-based dispersion is mixed with an additive to obtain the polyhydroxyalkanoate water-based coating. The dispersant and the talc are added in the cell wall breaking process.

2. The method for preparing the polyhydroxyalkanoate waterborne coating according to claim 1, characterized in that, The total mass of the dispersant and the talc accounts for 2-10% of the mass of the fermentation liquor before addition, and the mass ratio of the dispersant to the talc is 1:5-5:1, preferably 2:3-3:

2.

3. The method for producing a polyhydroxyalkanoate aqueous coating according to claim 1 or 2, characterized by, The dispersant is selected from one or more of sodium hexametaphosphate, polyacrylic acid sodium salt, styrene maleic anhydride sodium salt, styrene maleic anhydride ammonium salt, polysorbate, sodium oleate and ethyl sulfate sodium.

4. The method for producing a polyhydroxyalkanoate aqueous coating according to claim 1 or 2, characterized by, The adding time of the dispersant and the talc is limited to the condition that the polyhydroxyalkanoate release amount is not more than 60% of the total release amount.

5. The method for producing a polyhydroxyalkanoate aqueous coating according to claim 1 or 2, characterized by, The cell wall breaking mode is selected from one or more of enzymatic hydrolysis, chemical reagent method, high-pressure homogenization, grinding and ultrasonic treatment.

6. The method for producing a polyhydroxyalkanoate aqueous coating according to claim 1 or 2, characterized by, The solid content of the polyhydroxyalkanoate water-based dispersion is adjusted to be between 30-55%.

7. The method of preparing a polyhydroxyalkanoate aqueous coating according to claim 1 or 2, characterized in that, The additive comprises one or more of bactericides, wetting agents, thickening agents, leveling agents and defoaming agents. Preferably, the additive amount of each additive is 0.01-0.5% based on the mass of the polyhydroxyalkanoate water-based dispersion after the solid content is adjusted.

8. An aqueous coating, characterized in that The polyhydroxyalkanoate water-based coating comprises polyhydroxyalkanoate, talc and a dispersant which can be used to improve the dispersibility of the polyhydroxyalkanoate suspended particles.

9. The aqueous coating of claim 8, wherein, The water-based coating comprises the polyhydroxyalkanoate water-based coating prepared by the preparation method in any one of claims 1-7. Preferably, the viscosity of the polyhydroxyalkanoate water-based coating is 200-1000 mPa.s. The polyhydroxyalkanoate in the polyhydroxyalkanoate water-based coating comprises one or more of PHB, P34HB, PHBV, PHBHHx, PHBHO, PHBHN, P3HB4HB3HV and P3HB4HB5HV.

10. A water-resistant coating film, characterized by, The water-based coating in claim 8 or 9 is coated on the surface of a substrate to obtain; The substrate is selected from plastic substrate, metal substrate, paper substrate, ceramic substrate or glass substrate, preferably paper substrate. The substrate is a planar substrate or a non-planar substrate.

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