A bio-based water-based coating and its preparation method

Abstract

This invention relates to a bio-based water-based coating and its preparation method, belonging to the interdisciplinary technical fields of high-value-added utilization of biomass resources and water-based coatings. By weight fraction, the bio-based water-based coating comprises: 30-50 parts of pig hair-based prepolymer, 10-20 parts of a multi-component double-bonded organic compound, 10-30 parts of a multi-component organic aldehyde, 8-20 parts of a multi-component organic amine, 4-5 parts of emulsifier, 0.3-0.5 parts of defoamer, and 30-40 parts of deionized water. This invention uses pig hair, a byproduct of slaughterhouses, as raw material. The pig hair is chemically modified to obtain a prepolymer with amino and thiol groups in its molecular chain. This prepolymer is further reacted with a multi-component double-bonded organic compound, a multi-component organic aldehyde, and a multi-component organic amine to form a cross-linked bio-based polymer, providing a low-cost and environmentally friendly new material for bio-based coatings. More importantly, the preparation method of the bio-based water-based coating provided by this invention is a solvent reaction, which is easy to scale up.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary 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 its preparation method. Background Technology

[0002] In the field of coatings applications, bio-based materials, especially vegetable oils, have been widely used to prepare novel green and environmentally friendly coatings. This is because vegetable oils are non-toxic, low in volatility, biodegradable, and readily available. Since the 19th century, a series of studies have been conducted on vegetable oil-based polymers. For example, triglycerides in vegetable oils, after glycerol alcoholysis, yield monoglycerides for the preparation of alkyd resins; drying oils or fatty acids are first anhydrinated with maleic acid and then transesterified with epoxy prepolymers to prepare fatty acid-modified epoxy coatings; soybean oil, after epoxidation, is combined with acrylates to prepare epoxidized soybean oil acrylate resins; monoglycerides are also polyols that can react with diisocyanates to prepare polyurethanes; vegetable oils used to prepare water-based polyurethanes include sunflower oil, castor oil, rapeseed oil, and soybean oil; tung oil, after thermal crosslinking polymerization, directly forms a biodegradable coating. However, as human dietary demand for vegetable oils continues to increase, using vegetable oils as raw materials for alkyd resins results in high production costs.

[0003] Pig hair, a byproduct of slaughterhouses, is often discarded directly as solid waste, resulting in resource waste and environmental burden. However, the main component of pig hair is keratin, synthesized from amino acids such as glutamic acid, cysteine, and arginine through a condensation reaction. These amino acids contain abundant disulfide bonds and amino groups. By decomposing and activating pig hair, these groups can be exposed and reused as chemical reaction sites. However, no research on this topic has been reported to date. Summary of the Invention

[0004] To address the aforementioned shortcomings, the present invention aims to provide a bio-based water-based coating and its preparation method, particularly using slaughterhouse byproducts, namely pig hair, as raw material. The pig hair is chemically modified to obtain a prepolymer with amino and thiol groups in its molecular chain. This prepolymer is then reacted with multi-component double-bonded organic compounds, multi-component organic aldehydes, and multi-component organic amines to form a molecular chain network cross-linked bio-based polymer, providing a new, inexpensive, and environmentally friendly material for bio-based coatings.

[0005] The specific technical solution is as follows:

[0006] A bio-based water-based coating, by weight, comprises: 30-50 parts of pig hair-based prepolymer, 10-20 parts of a multi-component double-bonded organic compound, 10-30 parts of a multi-component organic aldehyde, 8-20 parts of a multi-component organic amine, 4-5 parts of emulsifier, 0.3-0.5 parts of defoamer, and 30-40 parts of deionized water; the preparation method of the pig hair-based prepolymer includes the following steps:

[0007] S1 Impurity Removal: Rinse the collected pig hair with water to remove pig feces, internal organs, and skin impurities. Then soak the pig hair in a 1:1 acetone / methanol mixed solution and mix for 12 to 24 hours at a stirring speed of 200 to 500 rpm. After that, rinse the pig hair with water and dry it in an oven at 80 to 100°C for 12 to 18 hours. Finally, crush the dried pig hair into fine particles using a pulverizer to obtain fine-particle pig hair.

[0008] S2 Pig Hair Decomposition: 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 pig hair particles were then placed in a mixed solution of urea / sodium metabisulfite / sodium hydroxide and treated at a stirring speed of 500–800 rpm and a temperature of 80–100 °C for 12–24 hours to promote pig hair decomposition. After the reaction was completed, the solution was filtered through a 120-mesh stainless steel sieve. The filtrate was collected, centrifuged to remove the pig hair residue, and then the centrifuged filtrate was dialyzed to remove urea, sodium metabisulfite, and sodium hydroxide, yielding a purified pig hair extract. The mass ratio of the fine pig hair particles to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:10–18.

[0009] S3 Activation: Adjust the pH of the mixed solution to 1-3 with 2M hydrochloric acid. React for 3-5 hours at a stirring speed of 300-500 rpm and a temperature of 50-60℃. Then filter and collect the residue. Wash the residue with deionized water until the pH of the washing solution is neutral. Take the residue to obtain the pig hair-based prepolymer.

[0010] In some embodiments, the multi-component double-bonded organic compound is one or more combinations of maleimide and myrcene.

[0011] In some embodiments, the multi-organic aldehyde is one or more combinations of malondialdehyde and succinaldehyde.

[0012] In some embodiments, the polymeric organic amine is one or more combinations of ethylenediamine and hexamethylenediamine.

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

[0014] In some embodiments, the defoamer is one or more combinations of polysiloxane and ethylene glycol siloxane.

[0015] This invention also provides a method for preparing the above-mentioned bio-based aquatic system, the method comprising the following steps:

[0016] In a multifunctional reactor, according to the formula weight, add pig hair-based prepolymer, multi-component double-bonded organic compound, emulsifier, defoamer, and deionized water in sequence. While purging nitrogen, stir at a speed of 200-500 r / min for 10-20 minutes, react at a temperature of 50-60℃ for 1-3 hours, and then continue to purge nitrogen for 5 minutes.

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

[0018] After the reaction in step S6 is complete, the temperature of the mixed solution is raised to 100-120°C. During this period, the generated water vapor is separated using a water separator. Then, the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 30-40 wt%, heating is stopped, and the temperature is lowered to below 30°C. The viscosity of the mixed solution is then tested. When the viscosity of the mixed solution is adjusted to 10000-12000 cps / 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 material, the production cost is low, and at the same time, it can reduce the direct disposal of pig hair in the environment and reduce the burden on the environment.

[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 that are 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 materials. The pig hair is subjected to impurity removal, pig hair decomposition and activation treatment steps to obtain bio-based polymers with smaller molecular chains. At the same time, the surface of the bio-based polymer chains is exposed with a large number of primary amino groups and thiol groups with high chemical reactivity. These groups react with multiple double bond organic compounds, multiple organic aldehydes and multiple organic amines to generate network cross-linked bio-based polymers, thereby improving the strength of bio-based water-based coatings after film formation. Attached Figure Description

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

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

[0025] Figure 3 Infrared spectra of the porcine hair-based prepolymers prepared in Examples 2 and 3. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, technical process steps, specific implementation conditions and materials. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort 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 surface impurities. Then, the pig hair was soaked in a 1:1 acetone / methanol mixture at a stirring speed of 200 rpm for 24 hours. Afterward, the pig hair was rinsed with water and dried in an oven at 80℃ for 18 hours. Finally, the dried pig hair was pulverized into fine particles using a pulverizer. Infrared spectroscopy analysis was then performed on the fine-particle pig hair. Figure 2 As shown.

[0029] Example 2

[0030] The collected pig hair was rinsed with water to remove pig feces, internal organs, and skin impurities. Then, the pig hair was soaked in a 1:1 acetone / methanol mixture and stirred at 300 rpm for 18 hours. After that, the pig hair was rinsed with water and dried in a 90℃ oven for 15 hours. Finally, the dried pig hair was crushed into fine particles using a pulverizer 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-particle pig hair was then treated in a mixed solution of urea / sodium metabisulfite / sodium hydroxide at 90°C for 18 hours with stirring at 600 rpm to promote hair decomposition. The mass ratio of the fine-particle pig hair to the mixed solution was 1:14. After the reaction, the mixture was filtered through a 120-mesh stainless steel sieve. The filtrate was collected, centrifuged to remove the pig hair residue, and then dialysis was performed on the centrifuged filtrate to remove urea, sodium metabisulfite, and sodium hydroxide, yielding a purified pig hair extract. The pH of the mixed solution was adjusted to 2 with 2M hydrochloric acid, and the reaction was carried out at 55°C for 4 hours with stirring at 400 rpm. The residue was then collected by filtration and washed with deionized water until the pH of the washing solution was neutral. The residue was then collected, yielding the pig hair-based prepolymer, which was subjected to infrared spectroscopy. Figure 3 As shown, comparison Figure 2 After decomposition and activation of pig hair, an absorption peak of thiol (2560) appeared in the infrared spectrum, indicating the presence of thiol groups in the molecular chain of pig hair prepolymer.

[0031] Example 3

[0032] The collected pig hair was rinsed with water to remove pig feces, internal organs, and skin impurities. Then, the pig hair was soaked in a 1:1 acetone / methanol mixture and stirred at 500 rpm for 12 hours. After that, the pig hair was 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 pulverizer 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-particle pig hair was then treated in a mixed solution of urea / sodium metabisulfite / sodium hydroxide at 100°C for 12 hours with stirring at 600 rpm to promote hair decomposition. The mass ratio of the fine-particle pig hair to the urea / sodium metabisulfite / sodium hydroxide solution was 1:18. After the reaction, the mixture was filtered through a 120-mesh stainless steel sieve. The filtrate was collected, centrifuged to remove the pig hair residue, and then dialysis was performed on the centrifuged filtrate to remove urea, sodium metabisulfite, and sodium hydroxide, yielding a purified pig hair extract. The pH of the mixed solution was adjusted to 1 with 2M hydrochloric acid, and the reaction was carried out at 60°C with stirring at 500 rpm 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 then collected, yielding the pig hair-based prepolymer, which was subjected to infrared spectroscopy. Figure 3 As shown, comparison Figure 2 After decomposition and activation of pig hair, an absorption peak of thiol (2560) appeared in the infrared spectrum, indicating the presence of thiol groups in the molecular chain of pig hair prepolymer.

[0033] Example 4

[0034] The amino content of Examples 1-6 was tested. 1 mL of the solutions prepared in Examples 2 and 3 were added to ninhydrin solution for a colorimetric reaction. The absorbance of the solutions after the reaction was then measured spectrophotometrically. Based on Beer-Lambert's law and the standard sample, the amino content of the solutions prepared in Examples 2 and 3 was found to be 0.85 mmol g, respectively. -1 and 0.91 mmol g -1 .

[0035] Example 5

[0036] like Figure 1As shown, in a multifunctional reactor, porcine hair-based prepolymer, myrcene, sodium dodecyl sulfate, polysiloxane, and deionized water were added sequentially according to the formula weight. While purging with nitrogen, the mixture was stirred at 200 rpm for 20 minutes and reacted at 50°C for 3 hours. Nitrogen was then continued to purge for 5 minutes. After stopping the nitrogen purge, malondialdehyde and ethylenediamine were added sequentially according to the formula amount. The mixture was reacted at 40°C with a stirring speed of 500 rpm for 1 hour. After the reaction was complete, the temperature of the mixed solution was raised to 100°C. During this period, water vapor was separated using a water separator. The solid content of the mixed solution was tested every 30 minutes. When the solid content reached 30 wt%, heating was stopped, and the temperature was lowered to below 30°C. The viscosity of the mixed solution was then tested. The viscosity of the mixed solution was adjusted to 10000 cps / 25°C to obtain the bio-based water-based coating.

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

[0038] pig hair-based prepolymer 30 copies Myrcene 10 copies malondialdehyde 10 copies ethylenediamine 8 copies Sodium dodecyl sulfate 4 copies Polysiloxane 0.3 copies Deionized water 30 copies

[0039] The porcine hair-based prepolymer used in this embodiment was prepared in Example 2.

[0040] According to GB / T 6739-1996 "Pencil Test Method for Hardness of Coating Film", the strength of the prepared bio-based water-based coating was tested by manually applying and curing it into a film (curing at 50℃ for 3 hours). The test results showed that the film strength was > B.

[0041] The VOC content of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Determination of Volatile Organic Compounds (VOC) Content in Paints and Varnishes - Difference Method", and the result was VOC≤12.4g / L.

[0042] Example 6

[0043] like Figure 1As shown, in a multifunctional reactor, porcine hair-based prepolymer, myrcene, sodium dodecyl sulfate, polysiloxane, and deionized water were added sequentially according to the formula weight. While purging with nitrogen, the mixture was stirred at 200 rpm for 20 minutes and reacted at 50°C for 3 hours. Nitrogen was then continued to purge for 5 minutes. After stopping the nitrogen purge, malondialdehyde and ethylenediamine were added sequentially according to the formula amount. The mixture was reacted at 40°C with a stirring speed of 500 rpm for 1 hour. After the reaction was complete, the temperature of the mixed solution was raised to 100°C. During this period, water vapor was separated using a water separator. The solid content of the mixed solution was tested every 30 minutes. When the solid content reached 30 wt%, heating was stopped, and the temperature was lowered to below 30°C. The viscosity of the mixed solution was then tested. The viscosity of the mixed solution was adjusted to 10000 cps / 25°C to obtain the bio-based water-based coating. The difference between the raw materials used in this embodiment and those used in Example 5 lies in the different porcine hair-based prepolymers. The porcine hair-based prepolymer used in this embodiment was prepared in Example 3.

[0044] According to GB / T 6739-1996 "Pencil Test Method for Hardness of Coating Film", the strength of the prepared bio-based water-based coating was tested by manually applying and curing it into a film (curing at 50℃ for 3 hours). The test results showed that the film strength was > B.

[0045] The VOC content of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Determination of Volatile Organic Compounds (VOC) Content in Paints and Varnishes - Difference Method", and the result was VOC≤10.2g / L.

[0046] Example 7

[0047] like Figure 1 As shown, in a multifunctional reactor, porcine hair-based prepolymer, myrcene, sodium dodecyl sulfate, ethylene glycol siloxane, and deionized water were added sequentially according to the formula weight. While purging with nitrogen, the mixture was stirred at 300 rpm for 15 minutes and reacted at 55°C for 2 hours. Nitrogen was then continued to purge for 5 minutes. After stopping the nitrogen purge, malondialdehyde and ethylenediamine were added sequentially according to the formula amount. The mixture was reacted at 45°C with a stirring speed of 300 rpm for 1 hour. After the reaction was complete, the temperature of the mixed solution was raised to 110°C. During this period, water vapor was separated using a water separator. The solid content of the mixed solution was tested every 30 minutes. When the solid content reached 35 wt%, heating was stopped, and the temperature was lowered to below 30°C. The viscosity of the mixed solution was then tested. The viscosity of the mixed solution was adjusted to 11000 cps / 25°C to obtain the bio-based water-based coating.

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

[0049] pig hair-based prepolymer 40 copies Myrcene 15 copies malondialdehyde 20 copies ethylenediamine 14 copies Sodium dodecyl sulfate 5 copies Ethylene glycol siloxane 0.4 copies Deionized water 35 copies

[0050] The porcine hair-based prepolymer used in this embodiment was prepared in Example 2.

[0051] According to GB / T 6739-1996 "Pencil Test Method for Hardness of Coating Film", the strength of the prepared bio-based water-based coating was tested by manually applying and curing it into a film (curing at 50℃ for 3 hours). The test results showed that the film strength was > B.

[0052] The VOC content of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Determination of Volatile Organic Compounds (VOC) Content in Paints and Varnishes - Difference Method", and the result was VOC≤12.1g / L.

[0053] Example 8

[0054] like Figure 1 As shown, in a multifunctional reactor, porcine hair-based prepolymer, myrcene, sodium dodecyl sulfate, ethylene glycol siloxane, and deionized water were added sequentially according to the formula weight. While purging with nitrogen, the mixture was stirred at 300 rpm for 15 minutes and reacted at 55°C for 2 hours. Nitrogen was then continued to purge for 5 minutes. After stopping the nitrogen purge, malondialdehyde and ethylenediamine were added sequentially according to the formula amount. The mixture was reacted at 45°C with a stirring speed of 300 rpm for 1 hour. After the reaction was complete, the temperature of the mixed solution was raised to 110°C. During this period, water vapor was separated using a water separator. The solid content of the mixed solution was tested every 30 minutes. When the solid content reached 35 wt%, heating was stopped, and the temperature was lowered to below 30°C. The viscosity of the mixed solution was then tested. The viscosity of the mixed solution was adjusted to 11000 cps / 25°C to obtain the bio-based water-based coating. The difference between the raw materials used in this embodiment and those used in Example 7 lies in the different porcine hair-based prepolymers. The porcine hair-based prepolymer used in this embodiment was prepared in Example 3.

[0055] According to GB / T 6739-1996 "Pencil Test Method for Hardness of Coating Film", the strength of the prepared bio-based water-based coating was tested by manually applying and curing it into a film (curing at 50℃ for 3 hours). The test results showed that the film strength was > B.

[0056] The VOC content of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Determination of Volatile Organic Compounds (VOC) Content in Paints and Varnishes - Difference Method", and the result was VOC≤14.5g / L.

[0057] Example 9

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

[0059] pig hair-based prepolymer 50 copies Myrcene 20 copies Butylene dialdehyde 30 copies Hexamethylenediamine 20 copies Sodium 2-acrylamido-methyl-propyl sulfate 5 copies Ethylene glycol siloxane 0.5 copies Deionized water 40 copies

[0060] The porcine hair-based prepolymer used in this embodiment was prepared in Example 2.

[0061] like Figure 1 As shown, in a multifunctional reactor, according to the formula weight, pig hair-based prepolymer, myrcene, sodium 2-acrylamido-methyl-propyl sulfate, ethylene glycol siloxane, and deionized water are added sequentially. While purging with nitrogen, the mixture is stirred at 500 rpm for 20 minutes and reacted at 60°C for 1 hour. Then, nitrogen is continued to purge for 5 minutes. After stopping nitrogen purging, butanol and hexamethylenediamine are added sequentially according to the formula amount. The mixture is reacted at 50°C with a stirring speed of 500 rpm for 0.5 hours. After the reaction is complete, the temperature of the mixed solution is raised to 120°C. During this period, water vapor is separated using a water separator. The solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 40 wt%, heating is stopped, and the temperature is lowered to below 30°C. The viscosity of the mixed solution is then tested. The viscosity of the mixed solution is adjusted to 10000–12000 cps / 25°C to obtain the bio-based water-based coating.

[0062] According to GB / T 6739-1996 "Pencil Test Method for Hardness of Coating Film", the strength of the prepared bio-based water-based coating was tested by manually applying and curing it into a film (curing at 50℃ for 3 hours). The test results showed that the film strength was > B.

[0063] The VOC content of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Determination of Volatile Organic Compounds (VOC) Content in Paints and Varnishes - Difference Method", and the result was VOC≤15.6g / L.

[0064] Example 10

[0065] like Figure 1As shown, in a multifunctional reactor, according to the formula weight, pig hair-based prepolymer, myrcene, sodium 2-acrylamido-methyl-propyl sulfate, ethylene glycol siloxane, and deionized water are added sequentially. While purging with nitrogen, the mixture is stirred at 500 rpm for 10 minutes and reacted at 60°C for 1 hour. Then, nitrogen is continued to purge for 5 minutes. After stopping nitrogen purging, butanol and hexamethylenediamine are added sequentially according to the formula amount. The mixture is reacted at 50°C with a stirring speed of 500 rpm for 0.5–1 hour. After the reaction is complete, the temperature of the mixed solution is raised to 120°C. During this period, water vapor is separated using a water separator. The solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 40 wt%, heating is stopped, and the temperature is lowered to below 30°C. The viscosity of the mixed solution is then tested. The viscosity of the mixed solution is adjusted to 12000 cps / 25°C to obtain the bio-based water-based coating. The difference between the raw materials used in this embodiment and those used in Example 9 lies in the different porcine hair-based prepolymers. The porcine hair-based prepolymer used in this embodiment was prepared in Example 3.

[0066] According to GB / T 6739-1996 "Pencil Test Method for Hardness of Coating Film", the strength of the prepared bio-based water-based coating was tested by manually applying and curing it into a film (curing at 50℃ for 3 hours). The test results showed that the film strength was > B.

[0067] The VOC content of the prepared bio-based water-based coating was tested according to GB / T 23985-2009 "Determination of Volatile Organic Compounds (VOC) Content in Paints and Varnishes - Difference Method", and the result was VOC≤10.6g / L.

[0068] Please note to all technical personnel: Although the present invention has been described according to the specific embodiments above, the inventive concept of the present invention is not limited to this invention. Any modifications that utilize the inventive concept will be included within the scope of protection of this patent.

Claims

1. A bio-based water-based coating, characterized in that, The bio-based water-based coating, by weight, comprises: 30-50 parts of porcine hair-based prepolymer, 10-20 parts of a multi-component double-bonded organic compound, 10-30 parts of a multi-component organic aldehyde, 8-20 parts of a multi-component organic amine, 4-5 parts of emulsifier, 0.3-0.5 parts of defoamer, and 30-40 parts of deionized water; the preparation method of the porcine hair-based prepolymer includes the following steps: S1 Impurity Removal: Rinse the collected pig hair with water to remove pig feces, internal organs, and skin impurities. Then soak the pig hair in a 1:1 acetone / methanol mixed solution and mix for 12 to 24 hours at a stirring speed of 200 to 500 rpm. After that, rinse the pig hair with water and dry it in an oven at 80 to 100°C for 12 to 18 hours. Finally, crush the dried pig hair into fine particles using a pulverizer to obtain fine-particle pig hair. S2 Pig Hair Decomposition: 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 pig hair particles were then placed in a mixed solution of urea / sodium metabisulfite / sodium hydroxide and treated at a stirring speed of 500–800 rpm and a temperature of 80–100 °C for 12–24 hours to promote pig hair decomposition. After the reaction was completed, the solution was filtered through a 120-mesh stainless steel sieve. The filtrate was collected, centrifuged to remove the pig hair residue, and then the centrifuged filtrate was dialyzed to remove urea, sodium metabisulfite, and sodium hydroxide, yielding a purified pig hair extract. The mass ratio of the fine pig hair particles to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:10–18. S3 Activation: Adjust the pH of the mixed solution to 1-3 with 2M hydrochloric acid. React for 3-5 hours at a stirring speed of 300-500 rpm and a temperature of 50-60℃. Then filter and collect the filter residue. Wash the filter residue with deionized water until the pH of the washing solution is neutral. Take the filter residue to obtain the pig hair-based prepolymer. The multi-component double-bonded organic compound is one or a combination of maleimide and myrcene; The preparation method of the bio-based water-based coating includes the following steps: In a multifunctional reactor, according to the formula weight, add pig hair-based prepolymer, multi-component double-bonded organic compound, emulsifier, defoamer, and deionized water in sequence. While purging nitrogen, stir at a speed of 200-500 r / min for 10-20 minutes, react at a temperature of 50-60℃ for 1-3 hours, and then continue to purge nitrogen for 5 minutes. S5 Stop the nitrogen flow, add the poly-organic aldehyde and poly-organic amine in sequence according to the formula amount, and react for 0.5 to 1 hour at a temperature of 40 to 50 ℃ and a stirring speed of 200 to 500 r / min. After the reaction in step S6 is complete, the temperature of the mixed solution is raised to 100–120°C. During this period, the generated water vapor is separated using a water separator. Then, the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 30–40 wt%, heating is stopped, and the temperature is lowered to below 30°C. The viscosity of the mixed solution is then tested. When the viscosity of the mixed solution is adjusted to 10,000–12,000 cps / 25°C, the bio-based water-based coating is obtained.

2. The bio-based water-based coating as described in claim 1, characterized in that, The multi-component organic aldehyde is one or more combinations of malondialdehyde and succinaldehyde.

3. The bio-based water-based coating as described in claim 1, characterized in that, The polymeric organic amine is one or more of ethylenediamine and hexamethylenediamine.

4. The bio-based water-based coating as described in claim 1, characterized in that, The emulsifier is one or more of sodium dodecyl sulfate and sodium 2-acrylamido-methyl-propyl sulfate.

5. A bio-based water-based coating as described in claim 1, characterized in that, The defoamer is polysiloxane.

6. A method for preparing a bio-based water-based coating as described in any one of claims 1 to 5, characterized in that, The preparation method of the bio-based water-based coating includes the following steps: In a multifunctional reactor, according to the formula weight, add pig hair-based prepolymer, multi-component double-bonded organic compound, emulsifier, defoamer, and deionized water in sequence. While purging nitrogen, stir at a speed of 200-500 r / min for 10-20 minutes, react at a temperature of 50-60℃ for 1-3 hours, and then continue to purge nitrogen for 5 minutes. S5 Stop the nitrogen flow, add the poly-organic aldehyde and poly-organic amine in sequence according to the formula amount, and react for 0.5 to 1 hour at a temperature of 40 to 50°C and a stirring speed of 200 to 500 r / min. After the reaction in step S6 is complete, the temperature of the mixed solution is raised to 100-120°C. During this period, the generated water vapor is separated using a water separator. Then, the solid content of the mixed solution is tested every 30 minutes. When the solid content reaches 30-40 wt%, heating is stopped, and the temperature is lowered to below 30°C. The viscosity of the mixed solution is then tested. When the viscosity of the mixed solution is adjusted to 10000-12000 cps / 25°C, the bio-based water-based coating is obtained.

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