A water-based UV-curable coating and its preparation method

Abstract

This invention relates to a water-based UV-curable coating and its preparation method, belonging to the interdisciplinary field of biomass materials and UV-curable resin technology. The water-based UV-curable coating is composed of the following raw materials: 50-60 parts of acrylic-modified keratin, 10-18 parts of acrylic monomer, 10-15 parts of organic aldehyde, 0.5-1.2 parts of initiator, 3-6 parts of emulsifier, 0.5-0.7 parts of catalyst, 0.2-0.6 parts of defoamer, and 40-60 parts of deionized water. This invention converts pig hair into a bio-based polymer with active groups of thiol, amino, and acrylic groups on its molecular chain surface, which serves as the reaction raw material for acrylic resin. This polymer further reacts with the acrylic monomer to generate more polymers. Simultaneously, the double bonds and aldehyde groups in the organic aldehyde can react with the thiol and amino groups in the keratin, respectively, forming a network cross-linking between the keratin molecular chains and enhancing the strength of the resin film. This invention uses pig hair as a raw material, resulting in low cost, no organic solvents, and high strength and low VOCs after film formation, making it suitable for the field of environmentally friendly coatings.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of biomass materials and photocurable resin technology, and in particular relates to a water-based photocurable 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 a type of polyol 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, the demand for vegetable oils in human diets is constantly increasing. As a result, using vegetable oils as raw materials for synthetic resins results in high production costs. Therefore, it is urgent to explore a way to synthesize the resins that people need using inexpensive and widely available biomaterials.

[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] In view of the shortcomings of the prior art, the present invention aims to provide a water-based photocurable coating and its preparation method. Using slaughterhouse by-products, namely pig hair, as raw material, the method involves steps of impurity removal, pig hair decomposition, and acrylic group modification, which transforms the pig hair into bio-based polymers with active groups of thiol, amino, and acrylic groups on the surface of the molecular chain. These bio-based polymers serve as reactants for acrylic resins and react with acrylic monomers to further generate polymers. At the same time, the double bonds and aldehyde groups in the organic aldehyde can react with the thiol and amino groups in keratin, respectively, so that chemical bonds are formed between the keratin molecular chains, forming a network crosslink, which enhances the strength of the resin film.

[0005] The specific technical solution is as follows:

[0006] A water-based UV-curable coating, by weight, comprises the following raw materials: 50-60 parts of acrylic-modified keratin, 10-18 parts of acrylic monomer, 10-15 parts of organic aldehyde, 0.5-1.2 parts of initiator, 3-6 parts of emulsifier, 0.5-0.7 parts of catalyst, 0.2-0.6 parts of defoamer, and 40-60 parts of deionized water; the preparation method of the acrylic-modified keratin 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 mixture 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 ℃ 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 ℃ 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 Acrylic Acid Modification: The obtained pig hair extract was added to a multifunctional reactor, and the pH of the pig hair extract was adjusted to 12-14. Then, methyl 3-aldehyde-2-butenoate was added, nitrogen gas was introduced for 5-10 minutes, and the temperature was raised to 80-90℃. The reaction was carried out at a stirring speed of 500-1000 rpm for 2-4 hours. After the reaction was completed, the temperature was lowered to 30℃, and the pH of the mixed solution was adjusted to 3. The reaction was continued to be stirred for 8-12 hours. The reaction was stopped and allowed to stand for 0.5-1 hours. The liquid was separated, and the clear liquid was collected. Then, the salts were removed by dialysis to obtain the acrylic acid modified keratin solution.

[0010] In some embodiments, the acrylic monomer is one or more of ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, and isobutyl acrylate.

[0011] In some embodiments, the organic aldehyde is one or more combinations of acrolein, crotonaldehyde, 2-methyl-2-pentenal, malondialdehyde, and succinaldehyde.

[0012] In some embodiments, the initiator is one or more combinations of benzophenone, 2,4-dihydroxybenzophenone, and 2,2-dimethoxy-2-phenylacetophenone.

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

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

[0015] In some embodiments, the catalyst is one or more combinations of antimony trioxide and Sn(Oct)2.

[0016] This invention also provides a method for preparing the above-mentioned water-based photocurable coating, characterized in that the preparation method includes the following steps:

[0017] S4 adds acrylic-modified keratin, acrylic monomer, initiator, emulsifier, defoamer and deionized water into a multi-functional reactor, purges nitrogen for 20 minutes to remove air from the reactor, and stirs for 30 to 60 minutes at a stirring speed of 800 to 1000 rpm and a temperature of 40 to 60°C to form a uniform emulsion.

[0018] Add organic aldehydes and catalyst to S5, heat to 50-60 °C, stir for 30-60 minutes, then heat to 108-120 °C and react at a constant temperature for 2-4 hours;

[0019] After the reaction is complete, the temperature is lowered to 50 °C, and the viscosity of the mixed solution is adjusted to 9000~12000 cps / 25 °C. Then, the mixture is dispersed at high speed for 1~3 hours at a stirring speed of 8000~10000 rpm to form a stable emulsion, which is the water-based photocurable coating.

[0020] The present invention has the following advantages:

[0021] (1) Using pig hair 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;

[0022] (2) The formula does not involve the use of organic solvents, and the subsequent use of water-based UV-cured coatings will not produce gases that are harmful to human health, which is in line with the green and environmentally friendly production concept.

[0023] (3) In this invention, pig hair is transformed into bio-based polymers with active groups of thiol, amino and acrylic groups on the surface of molecular chains through the steps of removing impurities, decomposing pig hair and modifying acrylic groups. These polymers are used as reaction raw materials for acrylic resins and react with acrylic monomers to further generate polymers. At the same time, the double bonds and aldehyde groups in organic aldehydes can react with the thiol and amino groups in keratin, respectively, so that chemical bonds are formed between keratin molecular chains, forming a network crosslink, which enhances the strength of the resin film. Attached Figure Description

[0024] Figure 1 A schematic diagram of the chemical reaction molecules in the preparation process of water-based UV-curable coatings;

[0025] Figure 2 Infrared spectrum of fine-particle pig hair prepared in Example 1;

[0026] Figure 3 Infrared spectra of acrylic-modified keratin prepared in Examples 6-8;

[0027] Figure 4 Optical photographs of the aqueous photocurable coatings prepared in Examples 9-11 after film formation;

[0028] Figure 5 Scanning electron microscope (SEM) images of the aqueous photocurable coatings prepared in Examples 9-11 after film formation;

[0029] Figure 6 Tensile curves of the water-based photocurable coatings prepared in Examples 9-14 after film formation. Detailed Implementation

[0030] 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.

[0031] Example 1

[0032] 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.

[0033] Example 2

[0034] 8 mol of urea, 0.2 mol of sodium metabisulfite, and 1 mol of sodium hydroxide were dissolved in 200 mL of distilled water. Then, the fine-particle pig hair prepared in Example 1 was treated in a mixed solution of urea / sodium metabisulfite / sodium hydroxide at a stirring speed of 500 rpm and a temperature of 100 °C for 12 hours to promote the decomposition of pig hair. The mass ratio of fine-particle pig hair to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:10. 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 to obtain a purified pig hair extract.

[0035] Example 3

[0036] 8 mol of urea, 0.2 mol of sodium metabisulfite, and 1 mol of sodium hydroxide were dissolved in 200 mL of distilled water. Then, the fine-particle pig hair prepared in Example 1 was 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 pig hair. The mass ratio of fine-particle pig hair to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:14. 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, resulting in a purified pig hair extract.

[0037] Example 4

[0038] 8 mol of urea, 0.2 mol of sodium metabisulfite, and 1 mol of sodium hydroxide were dissolved in 200 mL of distilled water. Then, the fine-particle pig hair prepared in Example 1 was treated in a mixed solution of urea / sodium metabisulfite / sodium hydroxide at a stirring speed of 800 rpm and a temperature of 100 °C for 12 hours to promote the decomposition of pig hair. The mass ratio of fine-particle pig hair to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:18. 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, resulting in a purified pig hair extract.

[0039] Example 5

[0040] The amino content of the pig hair extracts prepared in Examples 2-4 was tested. 1 mL of each solution prepared in Examples 2-4 was 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 2-4 was found to be 0.85 mmol / g. -10.93 mmol g -1 and 0.91 mmol g -1 .

[0041] Example 6

[0042] The pig hair extract obtained in Example 2 was added to a multifunctional reactor. The pH of the pig hair extract was adjusted to 12, and then methyl 3-aldehyde-2-butenoate was added. Nitrogen gas was purged for 5-10 minutes, and the temperature was raised to 80 °C. The reaction was carried out at a stirring speed of 500 rpm for 4 hours. After the reaction was completed, the temperature was lowered to 30 °C, and the pH of the mixed solution was adjusted to 3. The reaction was continued for 8 hours with stirring. The reaction was stopped and allowed to stand for 1 hour. The liquid was separated, and the clear liquid was collected. Salts were removed by dialysis to obtain an acrylic acid-modified keratin solution. The acrylic acid-modified keratin solution was subjected to infrared spectroscopy. The results are as follows: Figure 3 As shown, comparison Figure 2 The infrared spectrum of this embodiment shows characteristic peaks for C=C, C=O, and CO, indicating that the acrylic acid modification was successful.

[0043] Example 7

[0044] The pig hair extract obtained in Example 3 was added to a multifunctional reactor. The pH of the pig hair extract was adjusted to 13, and then methyl 3-aldehyde-2-butenoate was added. Nitrogen gas was introduced for 5-10 minutes, and the temperature was raised to 85 °C. The reaction was carried out at a stirring speed of 700 rpm for 3 hours. After the reaction was completed, the temperature was lowered to 30 °C, and the pH of the mixed solution was adjusted to 3. The reaction was continued for 10 hours, and then the reaction was stopped and allowed to stand for 1 hour. The liquid was separated, and the clear liquid was collected. Salts were removed by dialysis to obtain an acrylic acid-modified keratin solution. The acrylic acid-modified keratin solution was subjected to infrared spectroscopy. The results are as follows. Figure 3 As shown, comparison Figure 2 The infrared spectrum of this embodiment shows characteristic peaks for C=C, C=O, and CO, indicating that the acrylic acid modification was successful.

[0045] Example 8

[0046] The pig hair extract obtained in Example 4 was added to a multifunctional reactor. The pH of the pig hair extract was adjusted to 14, and then methyl 3-aldehyde-2-butenoate was added. Nitrogen gas was introduced for 5-10 minutes, and the temperature was raised to 90 °C. The reaction was carried out at a stirring speed of 1000 rpm for 2 hours. After the reaction was completed, the temperature was lowered to 30 °C, and the pH of the mixed solution was adjusted to 3. The reaction was continued for 12 hours with stirring. The reaction was stopped and allowed to stand for 1 hour. The liquid was separated, and the clear liquid was collected. Salts were removed by dialysis to obtain an acrylic acid-modified keratin solution. The acrylic acid-modified keratin solution was subjected to infrared spectroscopy. The results are as follows: Figure 3As shown, comparison Figure 2 The infrared spectrum of this embodiment shows characteristic peaks for C=C, C=O, and CO, indicating that the acrylic acid modification was successful.

[0047] Example 9

[0048] Table 1. Raw material ratios of the water-based UV-curing coating in Example 9

[0049]

[0050] The acrylic-modified keratin used in this example was prepared in Example 6.

[0051] Acrylic-modified keratin, ethyl acrylate, benzophenone, sodium 2-acrylamido-methyl-propyl sulfate, polysiloxane, and deionized water were added to a multifunctional reactor. Nitrogen gas was introduced for 20 minutes to remove air from the reactor. The mixture was stirred at 800 rpm for 60 minutes at 40 °C to form a homogeneous emulsion. Acrolein and antimony trioxide were added, and the mixture was heated to 50 °C and stirred for 60 minutes. Then, the temperature was increased to 108 °C and the mixture was kept at this temperature for 4 hours. After the reaction was completed, the temperature was lowered to 50 °C, and the viscosity of the mixed solution was adjusted to 9000 cps / 25 °C. The mixture was then dispersed at 8000 rpm for 3 hours to form a stable emulsion, thus obtaining the water-based photocurable coating. The prepared water-based photocurable coating was then cured under ultraviolet light (365 nm UV irradiation for 3 hours), and the resulting film is shown below. Figure 4 As shown in Figure a, it is semi-transparent. Scanning electron microscopy analysis was performed, as shown... Figure 5 As shown, a dense structure is formed on the surface, which is beneficial to improving the film strength.

[0052] According to GB / T 6739-1996 "Pencil Test Method for Hardness of Coating Film", the strength of the prepared water-based UV-curable coating was tested by manually curing it into a film (cured for 3 hours under UV light at 365 nm). The test results showed that the film strength was > B.

[0053] The VOC content of the prepared water-based UV-curable coating film was tested according to GB / T 23985-2009 "Determination of Volatile Organic Compound (VOC) Content in Paints and Varnishes - Difference Method", and the result was VOC≤62 g / L.

[0054] The water resistance of the prepared water-based UV-curable coating film was tested according to GB / T 1727-1992. After soaking for 48 hours, the water absorption rate was 11.8%.

[0055] Example 10

[0056] Table 2 Raw material ratios of water-based UV-curable coatings in Example 10

[0057]

[0058] The acrylic-modified keratin used in this example was prepared in Example 7.

[0059] like Figure 1 As shown, acrylic-modified keratin, butyl acrylate, 2,4-dihydroxybenzophenone, 2-acrylamido-methyl-propyl ammonium sulfate, GP-type glycerol polyether, and deionized water were added to a multifunctional reactor. Nitrogen gas was introduced for 20 minutes to remove air from the reactor. The mixture was stirred at 900 rpm for 45 minutes at 50 °C to form a homogeneous emulsion. Malondialdehyde and Sn(Oct)₂ were added, and the temperature was raised to 55 °C and stirred for 45 minutes. Then, the temperature was raised to 114 °C and the reaction was maintained at this temperature for 3 hours. After the reaction was completed, the temperature was lowered to 50 °C, and the viscosity of the mixed solution was adjusted to 10000 cps / 25 °C. The mixture was then dispersed at 9000 rpm for 2 hours to form a stable emulsion, thus obtaining the water-based photocurable coating. The prepared water-based photocurable coating was cured under ultraviolet light (365 nm UV irradiation for 3 hours), and the resulting film is shown below. Figure 4 As shown in Figure b, it is semi-transparent. Scanning electron microscopy analysis was performed, as shown... Figure 5 As shown, a dense structure is formed on the surface, which is beneficial to improving the film strength.

[0060] According to GB / T 6739-1996 "Pencil Test Method for Hardness of Coating Film", the strength of the prepared water-based UV-curable coating was tested by manually curing it into a film (cured for 3 hours under UV light at 365 nm). The test results showed that the film strength was > B.

[0061] The VOC content of the prepared water-based UV-curable coating film was tested according to GB / T 23985-2009 "Determination of Volatile Organic Compound (VOC) Content in Paints and Varnishes - Difference Method", and the result was VOC≤62 g / L.

[0062] The water resistance of the prepared water-based UV-curable coating film was tested according to GB / T 1727-1992. After soaking for 48 hours, the water absorption rate was 11.8%.

[0063] Example 11

[0064] like Figure 1As shown, acrylic-modified keratin, methacrylic acid, benzophenone, 2-acrylamido-methyl-propyl ammonium sulfate, ethylene glycol siloxane, and deionized water were added to a multifunctional reactor. Nitrogen gas was introduced for 20 minutes to remove air from the reactor. The mixture was stirred at 1000 rpm for 30 minutes at 60 °C to form a homogeneous emulsion. Crotonaldehyde and Sn(Oct)₂ were added, and the temperature was raised to 60 °C and stirred for 30 minutes. Then, the temperature was raised to 120 °C and the reaction was maintained at this temperature for 2 hours. After the reaction was completed, the temperature was lowered to 50 °C, and the viscosity of the mixed solution was adjusted to 12000 cps / 25 °C. The mixture was then dispersed at 10000 rpm for 1 hour to form a stable emulsion, thus obtaining the water-based photocurable coating. The prepared water-based photocurable coating was cured under ultraviolet light (365 nm UV irradiation for 3 hours), and the resulting film is shown below. Figure 4 As shown in Figure c, it is semi-transparent. Scanning electron microscopy analysis was performed, as shown... Figure 5 As shown, a dense structure is formed on the surface, which is beneficial to improving the film strength.

[0065] Table 3 Raw material ratios of water-based UV-curable coatings in Example 11

[0066]

[0067] The acrylic-modified keratin used in this example was prepared in Example 8.

[0068] According to GB / T 6739-1996 "Pencil Test Method for Hardness of Coating Film", the strength of the prepared water-based UV-curable coating was tested by manually curing it into a film (cured for 3 hours under UV light at 365 nm). The test results showed that the film strength was > B.

[0069] The VOC content of the prepared water-based UV-curable coating film was tested according to GB / T 23985-2009 "Determination of Volatile Organic Compound (VOC) Content in Paints and Varnishes - Difference Method", and the result was VOC≤62 g / L.

[0070] The water resistance of the prepared water-based UV-curable coating film was tested according to GB / T 1727-1992. After soaking for 48 hours, the water absorption rate was 11.8%.

[0071] Comparative Example 1

[0072] The process parameters are the same as in Example 9, and the formulation is the same except that acrolein in Example 9 is not added.

[0073] Comparative Example 2

[0074] The process parameters are the same as in Example 10, and the formula is the same except that malondialdehyde, which was not added in Example 10, is not included.

[0075] Comparative Example 3

[0076] The process parameters are the same as in Example 11, and the formulation is the same except that crotonaldehyde, which was not added in Example 11, is not included.

[0077] Strength test:

[0078] The tensile strength of the films formed by the water-based UV-curable coatings prepared in Examples 9-14 (cured for 3 hours under 365 nm UV light) was tested using a universal tensile testing machine. The test results are as follows: Figure 6 As shown, the tensile strengths of the water-based UV-curable coatings prepared in Examples 9-14 were 235.6 kPa, 278.9 kPa, 252.9 kPa, 118.7 kPa, 132.7 kPa, and 109.8 kPa, respectively, and the maximum deformations were 24.6%, 33.1%, 31.5%, 10.4%, 17.8%, and 11.6%, respectively.

[0079] By comparing Example 9 with Example 12, Example 10 with Example 13, Example 11 and Example 14, the addition of polyaldehyde can promote the formation of network crosslinks in the resin after film formation, thereby improving the strength and toughness of the film. Among the water-based photocurable coatings prepared in Examples 9, 10 and 11, the preparation process of Example 10 is the best, which provides guidance for subsequent actual production.

[0080] 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 water-based UV-curable coating, characterized in that, The water-based UV-curable coating, by weight, comprises the following raw materials: 50-60 parts acrylic-modified keratin, 10-18 parts acrylic monomer, 10-15 parts organic aldehyde, 0.5-1.2 parts initiator, 3-6 parts emulsifier, 0.5-0.7 parts catalyst, 0.2-0.6 parts defoamer, and 40-60 parts deionized water; the preparation method of the acrylic-modified keratin 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 ℃ 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 ℃ 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 Acrylic Acid Modification: The obtained pig hair extract is added to a multifunctional reactor, and the pH of the pig hair extract is adjusted to 12-14. Then, methyl 3-aldehyde-2-butenoate is added, nitrogen gas is introduced for 5-10 minutes, and the temperature is raised to 80-90 ℃. The reaction is carried out at a stirring speed of 500-1000 rpm for 2-4 hours. After the reaction is completed, the temperature is lowered to 30 ℃, and the pH of the mixed solution is adjusted to 3. The reaction is continued to be stirred for 8-12 hours. The reaction is stopped and allowed to stand for 0.5-1 hours. The liquid is separated, the clear liquid is collected, and then the salts are removed by dialysis to obtain acrylic acid modified keratin solution. The acrylic monomer is one or more of ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, and isobutyl acrylate; The organic aldehyde is one or more of acrolein, crotonaldehyde, and 2-methyl-2-pentenal.

2. The water-based UV-curable coating as described in claim 1, characterized in that, The initiator is one or more combinations of benzophenone, 2,4-dihydroxybenzophenone, and 2,2-dimethoxy-2-phenylacetophenone.

3. The water-based UV-curing coating as described in claim 1, characterized in that, The emulsifier is one or more of sodium 2-acrylamido-methyl-propyl sulfate and ammonium 2-acrylamido-methyl-propyl sulfate.

4. The water-based UV-curing coating as described in claim 1, characterized in that, The defoamer is one or more of polysiloxane, GP-type glycerol polyether, and ethylene glycol siloxane.

5. The water-based UV-curable coating as described in claim 1, characterized in that, The catalyst can be one or more of antimony trioxide and Sn(Oct)2.

6. A method for preparing a water-based UV-curable coating according to any one of claims 1 to 5, characterized in that, The preparation method includes the following steps: S4 adds acrylic-modified keratin, acrylic monomer, initiator, emulsifier, defoamer and deionized water into a multi-functional reactor, purges nitrogen for 20 minutes to remove air from the reactor, and stirs for 30 to 60 minutes at a stirring speed of 800 to 1000 rpm and a temperature of 40 to 60°C to form a uniform emulsion. Add organic aldehydes and catalyst to S5, heat to 50-60 °C, stir for 30-60 minutes, then heat to 108-120 °C and react at a constant temperature for 2-4 hours; After the reaction is complete, cool the mixture to 50 °C, adjust the viscosity of the mixed reaction system to 9000~12000 cps / 25 °C, and then disperse it at high speed for 1~3 hours at a stirring speed of 8000~10000 rpm to form a stable emulsion, thus obtaining the water-based photocurable coating.

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