Bio-based water-based coating and preparation method thereof

Abstract

The invention relates to a bio-based water-based coating and a preparation method thereof, and belongs to the technical field of high value-added utilization of biomass resources and crossing of water-based coatings. The bio-based water-based coating is prepared from the following components in parts by weight: 30 to 50 parts of pig hair-based prepolymer, 10 to 20 parts of multi-element double-bond organic compound, 10 to 30 parts of multi-element organic aldehyde, 8 to 20 parts of multi-element organic amine, 4 to 5 parts of emulsifier, 0.3 to 0.5 part of defoaming agent and 30 to 40 parts of deionized water. According to the invention, slaughter house by-product pig hair is used as a raw material, the pig hair is chemically modified to obtain a prepolymer with amino and sulfydryl in a molecular chain, and the prepolymer is further reacted with a multi-double bond organic compound, multi-element organic aldehyde and multi-element organic amine to form a molecular chain network cross-linked bio-based polymer. And a cheap, green and environment-friendly new material is provided for the bio-based paint. More importantly, the preparation method of the bio-based water-based coating provided by the invention is a solvent reaction, and is easy for large-scale preparation.

Description

Technical Field

[0001] The present invention belongs to the cross-technical field of high value-added utilization of biomass resources and water-based coatings, and in particular relates to a bio-based water-based coating and a preparation method thereof. Background Art

[0002] In the field of coatings, bio-based materials, particularly vegetable oils, have been widely used to produce new, environmentally friendly coatings. This is due to their non-toxicity, low volatility, biodegradability, and readily available raw materials. Since the 19th century, research on plant oil-based polymers has been extensive. For example, triglycerides in plant oils are hydrolyzed with glycerol to produce monoglycerides for use in the preparation of alkyd resins. Drying oils or fatty acids are first maleated and then transesterified with epoxy prepolymers to produce fatty acid-modified epoxy coatings. Soybean oil is epoxidized and then combined with acrylates to produce epoxidized soybean oil acrylate resins. Monoglycerides are also polyols that can react with diisocyanates to produce polyurethanes. Vegetable oils used to prepare water-based polyurethanes include sunflower oil, castor oil, rapeseed oil, and soybean oil. Tung oil can be directly cross-linked and polymerized to form biodegradable coatings. However, the demand for vegetable oils as dietary materials continues to increase, making the use of vegetable oils as raw materials for alkyd resins relatively costly.

[0003] Pig hair, a byproduct of slaughterhouses, is often discarded as solid waste, resulting in a waste of resources and a significant environmental burden. However, the primary component of pig hair is keratin, which is synthesized through a condensation reaction of amino acids such as glutamic acid, cystine, and arginine. These amino acids are rich in disulfide bonds and amino groups. Decomposition and activation of pig hair can expose these groups, allowing them to serve as active sites for chemical reactions. However, no studies have yet been conducted on this topic. Summary of the Invention

[0004] In view of the above-mentioned shortcomings, the purpose of the present invention is to provide a bio-based water-based paint and its preparation method, especially using slaughterhouse by-products, namely pig hair, as raw materials. The pig hair is chemically modified to obtain a prepolymer with amino and thiol groups in the molecular chain, which is further reacted with multi-double-bond organic compounds, multi-organic aldehydes and multi-organic amines to form a molecular chain network cross-linked bio-based polymer, providing a new cheap and green environmentally friendly material for bio-based coatings.

[0005] The specific technical solutions are as follows:

[0006] A bio-based water-based paint, comprising, by weight, 30-50 parts of a pig hair-based prepolymer, 10-20 parts of a polybasic double-bond organic compound, 10-30 parts of a polybasic organic aldehyde, 8-20 parts of a polybasic organic amine, 4-5 parts of an emulsifier, 0.3-0.5 parts of a defoaming agent, and 30-40 parts of deionized water. The preparation method of the pig hair-based prepolymer comprises the following steps:

[0007] S1 impurity removal: The collected pig hair is rinsed with water to remove pig feces, internal organs, and impurities on the skin, and then the pig hair is immersed in an acetone / methanol mixed solution with a mass ratio of 1:1, and mixed at a stirring speed of 200 to 500 rpm for 12 to 24 hours. The pig hair is then rinsed with water and dried in an oven at 80 to 100° C. for 12 to 18 hours. Finally, the dried pig hair is crushed into fine particles using a grinder to obtain fine particles of pig hair;

[0008] S2 Pig hair decomposition: 8 mol of urea, 0.2 mol of sodium metabisulfite and 1 mol of sodium hydroxide are dissolved in 200 mL of distilled water, and the resulting fine-grained pig hair is then treated in a mixed solution of urea / sodium metabisulfite / sodium hydroxide at a stirring speed of 500-800 rpm and a temperature of 80-100° C. for 12-24 hours to promote the decomposition of the pig hair. After the reaction is completed, the mixture is filtered with a 120-mesh stainless steel sieve, the filtrate is taken, and centrifuged to remove the pig hair residue. The centrifuged filtrate is then dialyzed to remove urea, sodium metabisulfite and sodium hydroxide to obtain a purified pig hair extract; the mass ratio of the fine-grained pig hair to the mixed solution of urea / sodium metabisulfite / sodium hydroxide is 1:10-18;

[0009] S3 activation: The obtained pig hair extract is adjusted to a pH of 1 to 3 with 2M hydrochloric acid, and the mixture is reacted for 3 to 5 hours at a stirring speed of 300 to 500 rpm and a temperature of 50 to 60°C. The residue is then collected by filtration and washed with deionized water until the pH of the washing solution is neutral. The residue is then taken to obtain a pig hair-based prepolymer.

[0010] In some embodiments, the polyvalent double bond organic compound is a combination of one or more of maleimide and myrcene.

[0011] In some embodiments, the polyvalent organic aldehyde is a combination of one or more of malondialdehyde and succinaldehyde.

[0012] In some embodiments, the polyvalent organic amine is a combination of one or more of ethylenediamine and hexamethylenediamine.

[0013] In some embodiments, the emulsifier is a combination of one or more of sodium lauryl sulfate and sodium 2-acrylamido-methyl-propyl sulfate.

[0014] In some embodiments, the defoaming agent is a combination of one or more of polysiloxane and glycol siloxane.

[0015] The present invention also provides a method for preparing the above-mentioned bio-based water system, the preparation method comprising the following steps:

[0016] S4: In a multifunctional reactor, pig hair-based prepolymer, multi-component double-bond organic compound, emulsifier, defoamer, and deionized water are added in order according to the formula weight, and while nitrogen is introduced, the mixture is stirred at a speed of 200-500 r / min for 10-20 minutes, and the reaction is carried out at a temperature of 50-60° C. for 1-3 hours, and then nitrogen is continued to be introduced for 5 minutes;

[0017] S5: Stop the nitrogen flow, add polyvalent organic aldehyde and polyvalent organic amine in order according to the formula, and react at a temperature of 40-50°C and a stirring speed of 200-500 r / min for 0.5-1 hour;

[0018] S6 After the reaction is completed, the temperature of the mixed solution is raised to 100-120°C, during which the generated water vapor is separated by a water separator, and then the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 30-40wt%, the heating is stopped, the temperature is lowered to below 30°C, and the viscosity of the mixed solution is tested. When the viscosity of the mixed solution is adjusted to 10,000-12,000cps / 25°C, the bio-based water-based coating is obtained.

[0019] The present invention has the following advantages:

[0020] (1) Using pig hair, a by-product of slaughterhouses, as raw materials has low production costs and can reduce the burden on the environment caused by direct disposal of pig hair;

[0021] (2) The formula does not involve the use of organic solvents, and the subsequent use of bio-based water-based coatings will not produce gases harmful to human health, which is in line with the green and environmentally friendly production concept;

[0022] (3) The present invention uses slaughterhouse by-products, namely pig hair, as raw material, and subjecting the pig hair to impurity removal, pig hair decomposition and activation treatment steps to obtain bio-based polymers with smaller molecular chains. At the same time, a large number of primary amino groups and thiol groups with high chemical reactivity are exposed on the surface of the bio-based polymer chains, which further react with multi-organic double-bond organic compounds, multi-organic aldehydes and multi-organic amines to generate network-crosslinked bio-based polymers, thereby improving the strength of the bio-based water-based coating after film formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the chemical reaction molecules for preparing bio-based water-based coatings;

[0024] Figure 2Infrared spectrum of fine-grained pig hair prepared in Example 1;

[0025] Figure 3 Infrared spectra of the pig hair-based prepolymers prepared in Examples 2 and 3. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings, technical process steps, specific implementation conditions and materials in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0027] Example 1

[0028] The collected pig hair was rinsed with water to remove pig feces, internal organs, and impurities on the surface of the pig hair. The pig hair was then immersed in a 1:1 acetone / methanol mixed solution and mixed for 24 hours at a stirring speed of 200 rpm. The pig hair was then rinsed with water and dried in an 80°C oven for 18 hours. Finally, the dried pig hair was crushed into fine particles using a grinder to obtain fine particles of pig hair. The infrared spectrum test was performed, as shown in FIG. Figure 2 shown.

[0029] Example 2

[0030] The collected pig hair was rinsed with water to remove pig feces, internal organs, and impurities on the surface of the pig hair. The pig hair was then immersed in a 1:1 acetone / methanol mixed solution and mixed for 18 hours at a stirring speed of 300 rpm. The pig hair was then rinsed with water and dried in an oven at 90°C for 15 hours. Finally, the dried pig hair was crushed into fine particles using a grinder to obtain fine-particle pig hair. 8 mol of urea, 0.2 mol of sodium metabisulfite, and 1 mol of sodium hydroxide were dissolved in 200 mL of distilled water. The resulting fine-grained pig hair was then treated in a mixed solution of urea / sodium metabisulfite / sodium hydroxide at a stirring speed of 600 rpm and a temperature of 90°C for 18 hours to promote the decomposition of the pig hair. The mass ratio of the fine-grained pig hair to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:14. After the reaction was completed, the filtrate was filtered through a 120-mesh stainless steel sieve, the filtrate was centrifuged to remove the pig hair residue, and the centrifuged filtrate was dialyzed to remove urea, sodium metabisulfite, and sodium hydroxide to obtain a purified pig hair extract. The obtained pig hair extract was adjusted to pH 2 with 2M hydrochloric acid, and the mixture was reacted at a stirring speed of 400 rpm and a temperature of 55°C for 4 hours. The filter residue was then collected by filtration and washed with deionized water until the pH of the washing solution was neutral. The filter residue was taken to obtain a pig hair-based prepolymer and subjected to infrared spectroscopy testing. Figure 3 As shown, compared Figure 2 After the pig hair decomposition and activation treatment, the absorption peak of thiol (2560) appeared in the infrared spectrum, indicating the presence of thiol in the pig hair prepolymer molecular chain.

[0031] Example 3

[0032] The collected pig hair was rinsed with water to remove pig feces, internal organs, and impurities on the surface of the pig hair. The pig hair was then immersed in a 1:1 acetone / methanol mixed solution and mixed for 12 hours at a stirring speed of 500 rpm. The pig hair was then rinsed with water and dried in an oven at 100°C for 18 hours. Finally, the dried pig hair was crushed into fine particles using a grinder to obtain fine-particle pig hair. 8 mol of urea, 0.2 mol of sodium metabisulfite, and 1 mol of sodium hydroxide were dissolved in 200 mL of distilled water. The resulting fine-grained pig hair was then treated in a mixed solution of urea / sodium metabisulfite / sodium hydroxide at a stirring speed of 600 rpm and a temperature of 100°C for 12 hours to promote the decomposition of the pig hair. The mass ratio of the fine-grained pig hair to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:18. After the reaction was completed, the mixture was filtered through a 120-mesh stainless steel sieve, the filtrate was collected, and centrifuged to remove the pig hair residue. The centrifuged filtrate was then dialyzed to remove urea, sodium metabisulfite, and sodium hydroxide to obtain a purified pig hair extract. The obtained pig hair extract was adjusted to pH 1 with 2 M hydrochloric acid, and the mixture was reacted at a stirring speed of 500 rpm and a temperature of 60°C for 3 hours. The residue was then collected by filtration and washed with deionized water until the pH of the washing solution was neutral. The residue was collected to obtain a pig hair-based prepolymer and subjected to infrared spectroscopy testing. Figure 3 As shown, compared Figure 2 After the pig hair decomposition and activation treatment, the absorption peak of thiol (2560) appeared in the infrared spectrum, indicating the presence of thiol in the pig hair prepolymer molecular chain.

[0033] Example 4

[0034] The amino content of Examples 1 to 6 was tested. 1 mL of the solutions prepared in Examples 2 and 3 were added to a ninhydrin solution for color reaction. The absorbance of the reaction solution was measured by spectrophotometry. According to the Lambert-Beer law and the standard sample, the amino content of the solutions prepared in Examples 2 and 3 was 0.85 mmol g, respectively. -1 and 0.91mmolg -1 .

[0035] Example 5

[0036] like Figure 1As shown, in a multifunctional reactor, pig hair-based prepolymer, myrcene, sodium lauryl sulfate, polysiloxane, and deionized water are added in sequence according to the formula weight, and stirred at a speed of 200 r / min for 20 minutes while introducing nitrogen. The reaction is carried out at a temperature of 50°C for 3 hours, and then nitrogen is continued to be introduced for 5 minutes; the introduction of nitrogen is stopped, and malondialdehyde and ethylenediamine are added in sequence according to the formula amount, and the reaction is carried out at a temperature of 40°C and a stirring speed of 500 r / min for 1 hour; after the reaction is completed, the temperature of the mixed solution is raised to 100°C, and the water vapor generated is separated by a water separator during the reaction, and then the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 30wt%, the heating is stopped, the temperature is reduced to below 30°C, the viscosity of the mixed solution is tested, and the viscosity of the mixed solution is adjusted to 10000cps / 25°C to obtain the bio-based water-based coating.

[0037] Table 1 Raw material ratio of bio-based water-based coating in Example 5

[0038] Pig hair based prepolymer 30 servings Myrcene 10 servings Malondialdehyde 10 servings Ethylenediamine 8 servings Sodium dodecylsulfate 4 servings polysiloxane 0.3 parts Deionized water 30 servings

[0039] The pig hair-based prepolymer used in this example is prepared in Example 2.

[0040] According to GB / T 6739-1996 "Coating Hardness Pencil Test Method", the prepared bio-based water-based coating was coated manually and cured into a thin film (cured at 50°C for 3 hours) and the strength was tested. The test results showed that the film strength was >B.

[0041] The VOC of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Paints and varnishes - Determination of volatile organic compound (VOC) content - Difference method", and the result was VOC≤12.4g / L.

[0042] Example 6

[0043] like Figure 1As shown, in a multifunctional reactor, pig hair-based prepolymer, myrcene, sodium lauryl sulfate, polysiloxane, and deionized water are added in sequence according to the formula weight, and stirred at a speed of 200 r / min for 20 minutes while introducing nitrogen. The reaction is carried out at a temperature of 50°C for 3 hours, and then nitrogen is continued to be introduced for 5 minutes; the introduction of nitrogen is stopped, and malondialdehyde and ethylenediamine are added in sequence according to the formula amount, and the reaction is carried out at a temperature of 40°C and a stirring speed of 500 r / min for 1 hour; after the reaction is completed, the temperature of the mixed solution is raised to 100°C, and the water vapor generated is separated by a water separator during the reaction, and then the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 30wt%, the heating is stopped, the temperature is reduced to below 30°C, the viscosity of the mixed solution is tested, and the viscosity of the mixed solution is adjusted to 10000cps / 25°C to obtain the bio-based water-based coating. The difference between the raw materials used in this embodiment and the raw materials used in Example 5 is that the pig hair-based prepolymer is different. The pig hair-based prepolymer in this embodiment is prepared in Example 3.

[0044] According to GB / T 6739-1996 "Coating Hardness Pencil Test Method", the prepared bio-based water-based coating was coated manually and cured into a thin film (cured at 50°C for 3 hours) and the strength was tested. The test results showed that the film strength was >B.

[0045] The VOC of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Paints and varnishes - Determination of volatile organic compound (VOC) content - Difference method", and the result was VOC≤10.2g / L.

[0046] Example 7

[0047] like Figure 1 As shown, in a multifunctional reactor, pig hair-based prepolymer, myrcene, sodium lauryl sulfate, ethylene glycol siloxane, and deionized water are added in sequence according to the formula weight, and stirred at a speed of 300 r / min for 15 minutes while introducing nitrogen. The reaction is carried out at a temperature of 55°C for 2 hours, and then nitrogen is continued to be introduced for 5 minutes; the introduction of nitrogen is stopped, and malondialdehyde and ethylenediamine are added in sequence according to the formula amount, and the reaction is carried out at a temperature of 45°C and a stirring speed of 300 r / min for 1 hour; after the reaction is completed, the temperature of the mixed solution is raised to 110°C, and the water vapor generated is separated by a water separator during the reaction, and then the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 35wt%, the heating is stopped, the temperature is reduced to below 30°C, the viscosity of the mixed solution is tested, and the viscosity of the mixed solution is adjusted to 11000cps / 25°C to obtain the bio-based water-based coating.

[0048] Table 2 Raw material ratios of bio-based water-based coatings in Example 7

[0049] Pig hair based prepolymer 40 servings Myrcene 15 servings Malondialdehyde 20 servings Ethylenediamine 14 servings Sodium dodecylsulfate 5 servings Ethylene glycol siloxane 0.4 serving Deionized water 35 servings

[0050] The pig hair-based prepolymer used in this example is prepared in Example 2.

[0051] According to GB / T 6739-1996 "Coating Hardness Pencil Test Method", the prepared bio-based water-based coating was coated manually and cured into a thin film (cured at 50°C for 3 hours) and the strength was tested. The test results showed that the film strength was >B.

[0052] The VOC of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Paints and varnishes - Determination of volatile organic compound (VOC) content - Difference method", and the result was VOC≤12.1g / L.

[0053] Example 8

[0054] like Figure 1 As shown, in a multifunctional reactor, pig hair-based prepolymer, myrcene, sodium lauryl sulfate, ethylene glycol siloxane, and deionized water are added in sequence according to the formula weight, and stirred at a speed of 300 r / min for 15 minutes while introducing nitrogen. The reaction is carried out at a temperature of 55°C for 2 hours, and then nitrogen is continued to be introduced for 5 minutes; the introduction of nitrogen is stopped, and malondialdehyde and ethylenediamine are added in sequence according to the formula amount, and the reaction is carried out at a temperature of 45°C and a stirring speed of 300 r / min for 1 hour; after the reaction is completed, the temperature of the mixed solution is raised to 110°C, and the water vapor generated is separated by a water separator during the reaction, and then the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 35wt%, the heating is stopped, the temperature is reduced to below 30°C, the viscosity of the mixed solution is tested, and the viscosity of the mixed solution is adjusted to 11000cps / 25°C to obtain the bio-based water-based coating. The difference between the raw materials used in this embodiment and the raw materials used in Example 7 is that the pig hair-based prepolymer is different. The pig hair-based prepolymer in this embodiment is prepared in Example 3.

[0055] According to GB / T 6739-1996 "Coating Hardness Pencil Test Method", the prepared bio-based water-based coating was coated manually and cured into a thin film (cured at 50°C for 3 hours) and the strength was tested. The test results showed that the film strength was >B.

[0056] The VOC of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Paints and varnishes - Determination of volatile organic compound (VOC) content - Difference method", and the result was VOC≤14.5g / L.

[0057] Example 9

[0058] Table 3 Raw material ratios of bio-based water-based coatings in Example 9

[0059] Pig hair based prepolymer 50 servings Myrcene 20 servings Succinaldehyde 30 servings Hexamethylenediamine 20 servings Sodium 2-acrylamido-methyl-propyl sulfate 5 servings Ethylene glycol siloxane 0.5 serving Deionized water 40 servings

[0060] The pig hair-based prepolymer used in this example is prepared in Example 2.

[0061] like Figure 1 As shown, in a multifunctional reactor, pig hair-based prepolymer, myrcene, 2-acrylamido-methyl-propyl sodium sulfate, ethylene glycol siloxane, and deionized water are added in sequence according to the formula weight, and stirred at a speed of 500 r / min for 20 minutes while introducing nitrogen. The reaction is carried out at a temperature of 60°C for 1 hour, and then nitrogen is continued to be introduced for 5 minutes; the introduction of nitrogen is stopped, and succinyl dialdehyde and hexamethylene diamine are added in sequence according to the formula amount, and the reaction is carried out at a temperature of 50°C and a stirring speed of 500 r / min for 0.5 hours. After the reaction is completed, the temperature of the mixed solution is raised to 120°C, during which the water vapor generated is separated by a water separator, and then the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 40wt%, the heating is stopped, the temperature is reduced to below 30°C, the viscosity of the mixed solution is tested, and the viscosity of the mixed solution is adjusted to 10,000-12,000 cps / 25°C to obtain the bio-based water-based coating.

[0062] According to GB / T 6739-1996 "Coating Hardness Pencil Test Method", the prepared bio-based water-based coating was coated manually and cured into a thin film (cured at 50°C for 3 hours) and the strength was tested. The test results showed that the film strength was >B.

[0063] The VOC of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Paints and varnishes - Determination of volatile organic compound (VOC) content - Difference method", and the result was VOC≤15.6g / L.

[0064] Example 10

[0065] like Figure 1As shown, in a multifunctional reactor, pig hair-based prepolymer, myrcene, 2-acrylamido-methyl-propyl sodium sulfate, ethylene glycol siloxane, and deionized water are added in sequence according to the formula weight, and stirred at a speed of 500 r / min for 10 minutes while introducing nitrogen. The reaction is carried out at a temperature of 60°C for 1 hour, and then nitrogen is continued to be introduced for 5 minutes; the introduction of nitrogen is stopped, and succinyl dialdehyde and hexamethylene diamine are added in sequence according to the formula amount, and the reaction is carried out at a temperature of 50°C and a stirring speed of 500 r / min for 0.5 to 1 hour; after the reaction is completed, the temperature of the mixed solution is raised to 120°C, during which the generated water vapor is separated by a water separator, and then the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 40wt%, the heating is stopped, the temperature is reduced to below 30°C, the viscosity of the mixed solution is tested, and the viscosity of the mixed solution is adjusted to 12000cps / 25°C to obtain the bio-based water-based coating. The difference between the raw materials used in this embodiment and the raw materials used in Example 9 is that the pig hair-based prepolymer is different. The pig hair-based prepolymer in this embodiment is prepared in Example 3.

[0066] According to GB / T 6739-1996 "Coating Hardness Pencil Test Method", the prepared bio-based water-based coating was coated manually and cured into a thin film (cured at 50°C for 3 hours) and the strength was tested. The test results showed that the film strength was >B.

[0067] The VOC of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Paints and varnishes - Determination of volatile organic compound (VOC) content - Difference method", and the result was VOC≤10.6g / L.

[0068] Technical personnel should note: Although the present invention has been described according to the above specific implementation methods, the inventive concept of the present invention is not limited to this invention. Any modification using the inventive concept will be included in the scope of protection of this patent.

Claims

1. A bio-based water-based paint, characterized in that: The composition of the bio-based water-based coating is, by weight, 30 to 50 parts of pig hair-based prepolymer, 10 to 20 parts of polybasic double-bond organic compound, 10 to 30 parts of polybasic organic aldehyde, 8 to 20 parts of polybasic organic amine, 4 to 5 parts of emulsifier, 0.3 to 0.5 parts of defoaming agent and 30 to 40 parts of deionized water. The preparation method of the pig hair-based prepolymer comprises the following steps: S1 impurity removal: The collected pig hair is rinsed with water to remove pig feces, internal organs, and impurities on the skin, and then the pig hair is immersed in an acetone / methanol mixed solution with a mass ratio of 1:1, and mixed at a stirring speed of 200 to 500 rpm for 12 to 24 hours. The pig hair is then rinsed with water and dried in an oven at 80 to 100° C. for 12 to 18 hours. Finally, the dried pig hair is crushed into fine particles using a grinder to obtain fine particles of pig hair; S2 Pig hair decomposition: 8 mol of urea, 0.2 mol of sodium metabisulfite and 1 mol of sodium hydroxide are dissolved in 200 mL of distilled water, and the resulting fine-grained pig hair is then treated in a mixed solution of urea / sodium metabisulfite / sodium hydroxide at a stirring speed of 500-800 rpm and a temperature of 80-100° C. for 12-24 hours to promote the decomposition of the pig hair. After the reaction is completed, the mixture is filtered with a 120-mesh stainless steel sieve, the filtrate is taken, and centrifuged to remove the pig hair residue. The centrifuged filtrate is then dialyzed to remove urea, sodium metabisulfite and sodium hydroxide to obtain a purified pig hair extract; the mass ratio of the fine-grained pig hair to the mixed solution of urea / sodium metabisulfite / sodium hydroxide is 1:10-18; S3 activation: The obtained pig hair extract is adjusted to a pH of 1 to 3 with 2M hydrochloric acid, and the mixture is reacted for 3 to 5 hours at a stirring speed of 300 to 500 rpm and a temperature of 50 to 60°C. The residue is then collected by filtration and washed with deionized water until the pH of the washing solution is neutral. The residue is then taken to obtain a pig hair-based prepolymer.

2. A bio-based water-based paint according to claim 1, characterized in that: The polyvalent double bond organic compound is a combination of one or more of maleimide and myrcene.

3. The bio-based water-based paint according to claim 1, characterized in that: The polyvalent organic aldehyde is a combination of one or more of malondialdehyde and succinaldehyde.

4. The bio-based water-based paint according to claim 1, characterized in that: The polyvalent organic amine is a combination of one or more of ethylenediamine and hexamethylenediamine.

5. The bio-based water-based paint according to claim 1, characterized in that: The emulsifier is a combination of one or more of sodium lauryl sulfate and 2-acrylamido-methyl-propyl sulfate.

6. The bio-based water-based paint according to claim 1, characterized in that: The defoaming agent is a combination of one or more of polysiloxane and ethylene glycol siloxane.

7. The method for preparing a bio-based water system according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S4: In a multifunctional reactor, pig hair-based prepolymer, multi-component double-bond organic compound, emulsifier, defoamer, and deionized water are added in order according to the formula weight, and while nitrogen is introduced, the mixture is stirred at a speed of 200-500 r / min for 10-20 minutes, and the reaction is carried out at a temperature of 50-60° C. for 1-3 hours, and then nitrogen is continued to be introduced for 5 minutes; S5: Stop the nitrogen flow, add polyvalent organic aldehyde and polyvalent organic amine in order according to the formula, and react at a temperature of 40-50°C and a stirring speed of 200-500 r / min for 0.5-1 hour; S6 After the reaction is completed, the temperature of the mixed solution is raised to 100-120°C, during which the generated water vapor is separated by a water separator, and then the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 30-40wt%, the heating is stopped, the temperature is lowered to below 30°C, and the viscosity of the mixed solution is tested. When the viscosity of the mixed solution is adjusted to 10,000-12,000cps / 25°C, the bio-based water-based coating is obtained.

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