Biodegradable coating based on aqueous phase dispersion and preparation method thereof

Abstract

The invention discloses a biodegradable coating based on an aqueous phase dispersion and a preparation method thereof, and belongs to the field of coatings. The biodegradable coating is specifically prepared from the following components in percentage by weight: 40 to 80 percent of water, 20 to 60 percent of modified polyhydroxybutyrate powder, 0.1 to 30 percent of PVA (Polyvinyl Alcohol) glue, 0.01 to 5 percent of surfactant, 0.01 to 5 percent of defoaming agent, 0.01 to 5 percent of wetting dispersant, 0.01 to 1 percent of biological inhibitor, 0.01 to 2 percent of pH (Potential of Hydrogen) regulator, 0.01 to 5 percent of rheology modifier, 0.01 to 5 percent of plasticizer and 0.01 to 35 percent of filler. After the prepared coating is applied to the surface of an object, the coating has excellent waterproof and oil-proof performance, and the situation that when the coating makes contact with food with large moisture and oil content, the moisture and the oil content can soak a package, consequently, the package is damaged, and the food package is unstable can be avoided. Moreover, the degradable plastic has good biodegradability, can be degraded in various environments, is more environment-friendly, and is higher in degradation speed at the same time.

Description

Technical Field

[0001] The invention relates to coatings, in particular to a biodegradable coating based on water phase dispersion and a preparation method thereof. Background Art

[0002] With the development of the food industry, in order to reduce the pollution to the environment caused by discarded food packaging and reduce the cost of food packaging, food packaging has gradually adopted some environmentally friendly and harmless materials such as paper as food packaging materials. However, in order to avoid water and oil on the food from soaking the food packaging, thereby causing damage to the food packaging. Usually, a waterproof and oil-proof coating is applied to the food packaging to ensure the stability of the food in the package. At present, the coatings applied to food packaging are generally PE, EAA, PLA, and PBAT coatings. These coatings will cause the food packaging to not be fully naturally degraded after it is lost, which will cause certain pollution to the environment, which is contrary to the original environmental protection concept. Summary of the invention

[0003] Object of the invention: The object of the present invention is to provide a biodegradable coating based on an aqueous dispersion; another object of the present invention is to provide a method for preparing a biodegradable coating based on an aqueous dispersion.

[0004] Technical solution: A biodegradable coating based on an aqueous dispersion, comprising the following components: water, modified polyhydroxybutyrate powder, PVA glue, surfactant, defoamer, wetting dispersant, bio-inhibitor, pH regulator, rheology modifier, plasticizer and filler.

[0005] Preferably, the biodegradable coating specifically comprises, by weight percentage, 40-80% water, 20-60% modified polyhydroxybutyrate powder, 0.1-30% PVA glue, 0.01-5% surfactant, 0.01-5% defoamer, 0.01-5% wetting dispersant, 0.01-1% bioinhibitor, 0.01-2% pH regulator, 0.01-5% rheology modifier, 0.01-5% plasticizer and 0.01-35% filler.

[0006] Preferably, the weight average molecular weight of the polyhydroxybutyrate powder is 100,000 to 1,500,000 Daltons.

[0007] Preferably, the surfactant is α-sulfonic fatty acid methyl ester, the defoamer is a biological defoamer, the wetting and dispersing agent is sodium lignosulfonate, the pH regulator is citric acid, and the rheology modifier is Fusion S-20 polymer, the plasticizer is polybutylene glycol succinate, and the filler is a mixture of montmorillonite, bentonite and silica.

[0008] Preferably, the modified polyhydroxybutyrate powder comprises polyhydroxybutyrate, starch, xylan, primary amine, calcium phosphate and tetraphenylboric acid;

[0009] The preparation method of modified polyhydroxybutyrate powder is as follows: first, polyhydroxybutyrate and primary amine are subjected to graft copolymerization reaction to form a copolymer, and then the copolymer is melted at 175-180°C to form a liquid copolymer, starch, xylan calcium phosphate and tetraphenylboric acid are mixed evenly to form a mixture, and the mixture is blended with the liquid copolymer in a weight ratio of 1:2-4. After mixing evenly, the mixture is cooled at room temperature to obtain a solid copolymer, and then the cooled solid copolymer is placed in a pulverizer and pulverized to obtain the modified polyhydroxybutyrate powder.

[0010] Preferably, the bioinhibitor is obtained by mixing quaternary ammonium thiocarbamate and silver nitrate in a ratio of 3-5:1-2.

[0011] A method for preparing a biodegradable coating based on an aqueous dispersion comprises the following steps:

[0012] S1, mixing water, modified polyhydroxybutyrate powder, surfactant, defoamer, plasticizer and seasoning to form a mixture of initial micelles;

[0013] S2, adding a wetting and dispersing agent to the mixture, and then homogenizing the mixture to form a dispersion;

[0014] S3, add the bio-inhibitor to the dispersion, mix well, and then add the pH regulator to adjust the pH of the dispersion to 8.0-9.5;

[0015] S4. Then, a modified rheological agent and PVA glue are added to the dispersion and mixed evenly to obtain a biodegradable coating based on an aqueous dispersion.

[0016] Preferably, the coating is 5 to 40 g / m 2 A weight of is applied to at least one food packaging surface in contact with the food.

[0017] Beneficial effects: After the coating prepared by the present invention is applied to the surface of an object, it has excellent waterproof and oil-proof properties, and can avoid the situation that the moisture and oil can soak the packaging when it comes into contact with food with high moisture and oil content, thereby causing damage to the packaging and causing instability of the food packaging. In addition, it has good biodegradability, can be degraded under various environments, and is more environmentally friendly. In addition, when the coating prepared by the present invention is degraded, the modified polyhydroxybutyrate therein contains starch, xylan, primary amine, calcium phosphate and tetraphenylborate, which can provide carbon sources, nitrogen sources and inorganic salts for the reproduction of microorganisms, thereby promoting the reproduction of microorganisms. At the same time, the silver nitrate in the biological inhibitor is photodecomposed to produce silver element, and absorbs light energy, thereby promoting the photodecomposition of quaternary ammonium thiocarbamate to produce alkaline tertiary amines, which in turn provide nitrogen sources for the reproduction of microorganisms, thereby further promoting the reproduction of microorganisms, and then can accelerate the degradation of the coating, so that the coating has a faster degradation rate. DETAILED DESCRIPTION

[0018] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments.

[0019] Example 1

[0020] A biodegradable coating based on an aqueous dispersion comprises, by weight percentage, 40% of water, 20% of modified polyhydroxybutyrate powder with a weight-average molecular weight of 100,000 Daltons, 0.1% of PVA glue, 0.01% of a surfactant, 0.01% of a defoaming agent, 0.01% of a wetting dispersant, 0.01% of a bio-inhibitor, 0.01% of a pH regulator, 0.01% of a rheology modifier, 0.01% of a plasticizer and 0.01% of a filler.

[0021] The surfactant is α-sulfonic fatty acid methyl ester, the defoamer is a biological defoamer, the wetting and dispersing agent is sodium wood sulfonate, the pH regulator is citric acid, and the rheology modifier is Fusion S-20 polymer, the plasticizer is polybutylene glycol succinate, and the filler is a mixture of montmorillonite, bentonite and silica.

[0022] The modified polyhydroxybutyrate powder comprises polyhydroxybutyrate, starch, xylan, primary amine, calcium phosphate and tetraphenylboric acid;

[0023] The preparation method of modified polyhydroxybutyrate powder is as follows: first, polyhydroxybutyrate and primary amine are subjected to graft copolymerization reaction to form a copolymer, and then the copolymer is melted at 175°C to form a liquid copolymer, starch, xylan calcium phosphate and tetraphenylboric acid are mixed evenly to form a mixture, and the mixture is blended with the liquid copolymer at a weight ratio of 1:2. After mixing evenly, the mixture is cooled at room temperature to obtain a solid copolymer, and then the cooled solid copolymer is placed in a grinder and crushed to obtain the modified polyhydroxybutyrate powder.

[0024] The bioinhibitor is obtained by mixing quaternary ammonium thiocarbamate and silver nitrate in a ratio of 3:1.

[0025] The preparation method of the biodegradable coating based on aqueous dispersion is as follows:

[0026] S1, mixing water, modified polyhydroxybutyrate powder, surfactant, defoamer, plasticizer and seasoning to form a mixture of initial micelles;

[0027] S2, adding a wetting and dispersing agent to the mixture, and then homogenizing the mixture to form a dispersion;

[0028] S3, add the bio-inhibitor to the dispersion, mix well, and then add the pH regulator to adjust the pH of the dispersion to 8.0;

[0029] S4. Then, a modified rheological agent and PVA glue are added to the dispersion and mixed evenly to obtain a biodegradable coating based on an aqueous dispersion.

[0030] After the biodegradable coating based on aqueous dispersion is prepared, 5 g / m 2 A weight of is applied to at least one food packaging surface in contact with the food.

[0031] Example 2

[0032] A biodegradable coating based on an aqueous dispersion comprises, by weight percentage, 65% of water, 37% of modified polyhydroxybutyrate powder having a weight average molecular weight of 900,000 Daltons, 16% of PVA glue, 2.3% of a surfactant, 3.1% of a defoaming agent, 2.6% of a wetting and dispersing agent, 0.3% of a bio-inhibitor, 0.9% of a pH regulator, 3.3% of a rheology modifier, 3.5% of a plasticizer, and 18% of a filler.

[0033] The surfactant is α-sulfonic fatty acid methyl ester, the defoamer is a biological defoamer, the wetting and dispersing agent is sodium wood sulfonate, the pH regulator is citric acid, and the rheology modifier is Fusion S-20 polymer, the plasticizer is polybutylene glycol succinate, and the filler is a mixture of montmorillonite, bentonite and silica.

[0034] The modified polyhydroxybutyrate powder comprises polyhydroxybutyrate, starch, xylan, primary amine, calcium phosphate and tetraphenylboric acid;

[0035] The preparation method of modified polyhydroxybutyrate powder is as follows: first, polyhydroxybutyrate and primary amine are subjected to graft copolymerization reaction to form a copolymer, and then the copolymer is melted at 177°C to form a liquid copolymer, starch, xylan calcium phosphate and tetraphenylboric acid are mixed evenly to form a mixture, the mixture and the liquid copolymer are blended in a weight ratio of 1:3, after mixing evenly, cooled at room temperature to obtain a solid copolymer, and then the cooled solid copolymer is placed in a grinder and crushed to obtain the modified polyhydroxybutyrate powder.

[0036] The bioinhibitor is obtained by mixing quaternary ammonium thiocarbamate and silver nitrate in a ratio of 3:2.

[0037] The preparation method of the biodegradable coating based on aqueous dispersion is as follows:

[0038] S1, mixing water, modified polyhydroxybutyrate powder, surfactant, defoamer, plasticizer and seasoning to form a mixture of initial micelles;

[0039] S2, adding a wetting and dispersing agent to the mixture, and then homogenizing the mixture to form a dispersion;

[0040] S3, add the bio-inhibitor to the dispersion, mix well, and then add the pH regulator to adjust the pH of the dispersion to 8.7;

[0041] S4. Then, a modified rheological agent and PVA glue are added to the dispersion and mixed evenly to obtain a biodegradable coating based on an aqueous dispersion.

[0042] After the biodegradable coating based on aqueous dispersion is prepared, the dry basis is 27g / m 2 A weight of is applied to at least one food packaging surface in contact with the food.

[0043] Example 3

[0044] A biodegradable coating based on an aqueous dispersion comprises, by weight percentage, 80% of water, 60% of modified polyhydroxybutyrate powder having a weight average molecular weight of 1,500,000 Daltons, 30% of PVA glue, 5% of a surfactant, 5% of a defoaming agent, 5% of a wetting and dispersing agent, 1% of a bio-inhibitor, 2% of a pH regulator, 5% of a rheology modifier, 5% of a plasticizer, and 35% of a filler.

[0045] The surfactant is α-sulfonic fatty acid methyl ester, the defoamer is a biological defoamer, the wetting and dispersing agent is sodium wood sulfonate, the pH regulator is citric acid, and the rheology modifier is Fusion S-20 polymer, the plasticizer is polybutylene glycol succinate, and the filler is a mixture of montmorillonite, bentonite and silica.

[0046] The modified polyhydroxybutyrate powder comprises polyhydroxybutyrate, starch, xylan, primary amine, calcium phosphate and tetraphenylboric acid;

[0047] The preparation method of modified polyhydroxybutyrate powder is as follows: first, polyhydroxybutyrate and primary amine are subjected to graft copolymerization reaction to form a copolymer, and then the copolymer is melted at 180°C to form a liquid copolymer, starch, xylan calcium phosphate and tetraphenylboric acid are mixed evenly to form a mixture, and the mixture is blended with the liquid copolymer at a weight ratio of 1:4. After mixing evenly, the mixture is cooled at room temperature to obtain a solid copolymer, and then the cooled solid copolymer is placed in a grinder and crushed to obtain the modified polyhydroxybutyrate powder.

[0048] The bioinhibitor is obtained by mixing quaternary ammonium thiocarbamate and silver nitrate in a ratio of 5:2.

[0049] The preparation method of the biodegradable coating based on aqueous dispersion is as follows:

[0050] S1, mixing water, modified polyhydroxybutyrate powder, surfactant, defoamer, plasticizer and seasoning to form a mixture of initial micelles;

[0051] S2, adding a wetting and dispersing agent to the mixture, and then homogenizing the mixture to form a dispersion;

[0052] S3, add the bio-inhibitor to the dispersion, mix well, and then add the pH regulator to adjust the pH of the dispersion to 9.5;

[0053] S4. Then, a modified rheological agent and PVA glue are added to the dispersion and mixed evenly to obtain a biodegradable coating based on an aqueous dispersion.

[0054] After the biodegradable coating based on aqueous dispersion is prepared, the dry basis is 40 g / m 2 A weight of is applied to at least one food packaging surface in contact with the food.

[0055] The properties of the biodegradable coatings based on aqueous dispersions prepared in Examples 1 to 3 are as follows:

[0056] color milky Viscosity (No. 3 Zahn cup, seconds) 20～60 Solid content 20％～60％ odor slight pH 8.0～9.5 Fineness (micrometer) ≤5 Melting temperature (Celsius) 160～175 Experimental film forming temperature (degrees Celsius) 160～180 Coating method Gravure and wire rod coating Coating amount (g / m2) Dry weight 5~40 Drying temperature (Celsius) 100～170 Hot pressing temperature (Celsius) 160～180 Cobb test of film-forming waterproof performance ≤20 Film-forming and oil-proof properties >Kit5 Hot water resistance test after film formation (degrees Celsius) 100

[0057] Comparative Example 1

[0058] A biodegradable coating based on an aqueous dispersion comprises, by weight percentage, 80% of water, 60% of polyhydroxybutyrate powder having a weight average molecular weight of 1,500,000 Daltons, 30% of PVA glue, 5% of a surfactant, 5% of a defoaming agent, 5% of a wetting and dispersing agent, 2% of a pH regulator, 5% of a rheology modifier, 5% of a plasticizer, and 35% of a filler.

[0059] The surfactant is α-sulfonic fatty acid methyl ester, the defoamer is a biological defoamer, the wetting and dispersing agent is sodium wood sulfonate, the pH regulator is citric acid, and the rheology modifier is Fusion S-20 polymer, the plasticizer is polybutylene glycol succinate, and the filler is a mixture of montmorillonite, bentonite and silica.

[0060] The preparation method of the biodegradable coating based on aqueous dispersion is as follows:

[0061] S1, mixing water, polyhydroxybutyrate powder, surfactant, defoaming agent, plasticizer and flavoring to form a mixture of initial micelles;

[0062] S2, adding a wetting and dispersing agent to the mixture, and then homogenizing the mixture to form a dispersion;

[0063] S3, adding a pH regulator to the dispersion to adjust the pH of the dispersion to 8.0;

[0064] S4. Then, a modified rheological agent and PVA glue are added to the dispersion and mixed evenly to obtain a biodegradable coating based on an aqueous dispersion.

[0065] After the biodegradable coating based on aqueous dispersion is prepared, the dry basis is 40 g / m 2 A weight of is applied to at least one food packaging surface in contact with the food.

[0066] Comparative Example 2

[0067] PE coating is 40g / m 2 A weight of is applied to at least one food packaging surface in contact with the food.

[0068] Comparative Example 3

[0069] EAA coating is 40g / m 2 A weight of is applied to at least one food packaging surface in contact with the food.

[0070] Comparative Example 4

[0071] PLA coating is 40g / m 2A weight of is applied to at least one food packaging surface in contact with the food.

[0072] Comparative Example 5

[0073] The PBAT coating is 40g / m 2 A weight of is applied to at least one food packaging surface in contact with the food.

[0074] The food packages coated with the coatings in Examples 1 to 3 and Comparative Examples 1 to 5 were placed in a natural environment and an artificial degradation environment for degradation, and the degradation effects were observed after one month. The degradation effects are shown in the following table:

[0075]

[0076]

[0077] Note: NG means no, OK means yes.

[0078] It can be seen from the above table that the biodegradable coating based on the aqueous dispersion prepared in the present invention can be fully degraded under different environments.

[0079] During the process of placing the food packages coated with coatings in Examples 1 to 3 and Comparative Examples 1 to 5 in a natural environment and an artificial degradation environment for degradation, check whether there is food packaging in different environments every day, and record the time when the food packaging is completely degraded in different environments. The complete degradation time (days) of food packaging in different environments is shown in the following table:

[0080]

[0081]

[0082] Note: -- means it cannot be completely degraded.

[0083] It can be seen from the above table that the biodegradable coating based on the aqueous dispersion prepared by the present invention can be degraded more quickly under different environments.

[0084] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A biodegradable coating based on an aqueous dispersion, characterized in that: The invention comprises the following components: water, modified polyhydroxybutyrate powder, PVA glue, surfactant, defoamer, wetting and dispersing agent, bio-inhibitor, pH regulator, rheology modifier, plasticizer and filler.

2. The biodegradable coating based on aqueous dispersion according to claim 1, characterized in that The biodegradable coating specifically comprises, by weight percentage, 40-80% of water, 20-60% of modified polyhydroxybutyrate powder, 0.1-30% of PVA glue, 0.01-5% of surfactant, 0.01-5% of defoamer, 0.01-5% of wetting dispersant, 0.01-1% of bio-inhibitor, 0.01-2% of pH regulator, 0.01-5% of rheology modifier, 0.01-5% of plasticizer and 0.01-35% of filler.

3. The biodegradable coating based on aqueous dispersion according to claim 1, characterized in that The weight average molecular weight of the modified polyhydroxybutyrate powder is 100,000 to 1,500,000 Daltons.

4. The biodegradable coating based on aqueous dispersion according to claim 1, characterized in that The surfactant is α-sulfonic fatty acid methyl ester, the defoamer is a biological defoamer, the wetting and dispersing agent is sodium wood sulfonate, the pH regulator is citric acid, and the rheology modifier is Fusion S-20 polymer, the plasticizer is polybutylene glycol succinate, and the filler is a mixture of montmorillonite, bentonite and silica.

5. The biodegradable coating based on aqueous dispersion according to claim 1, characterized in that The modified polyhydroxybutyrate powder comprises polyhydroxybutyrate, starch, xylan, primary amine, calcium phosphate and tetraphenylboric acid; The preparation method of modified polyhydroxybutyrate powder is as follows: first, polyhydroxybutyrate and primary amine are subjected to graft copolymerization reaction to form a copolymer, and then the copolymer is melted at 175-180°C to form a liquid copolymer, starch, xylan calcium phosphate and tetraphenylboric acid are mixed evenly to form a mixture, and the mixture is blended with the liquid copolymer in a weight ratio of 1:2-4. After mixing evenly, the mixture is cooled at room temperature to obtain a solid copolymer, and then the cooled solid copolymer is placed in a pulverizer and pulverized to obtain the modified polyhydroxybutyrate powder.

6. The biodegradable coating based on aqueous dispersion according to claim 1, characterized in that The bio-inhibitor is obtained by mixing quaternary ammonium thiocarbamate and silver nitrate in a ratio of 3-5:1-2.

7. A method for preparing a biodegradable coating based on an aqueous dispersion according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, mixing water, modified polyhydroxybutyrate powder, surfactant, defoamer, plasticizer and seasoning to form a mixture of initial micelles; S2, adding a wetting and dispersing agent to the mixture, and then homogenizing the mixture to form a dispersion; S3, add the bio-inhibitor to the dispersion, mix well, and then add the pH regulator to adjust the pH of the dispersion to 8.0-9.5; S4. Then, a modified rheological agent and PVA glue are added to the dispersion and mixed evenly to obtain a biodegradable coating based on an aqueous dispersion.

8. The method for preparing a biodegradable coating based on an aqueous dispersion according to claim 7, characterized in that: The coating is 5-40g / m2 on a dry basis. 2 A weight of is applied to at least one food packaging surface in contact with the food.

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