Waterproof coating prepared based on waste down feather and preparation method thereof

Abstract

The invention relates to a waterproof coating prepared based on waste down feather and a preparation method of the waterproof coating, and belongs to the technical field of high value-added utilization of waste down feather resources and crossing of waterproof coatings. The waterproof coating prepared based on the waste down feather is prepared from the following components in parts by weight: 20 to 30 parts of waste down feather-based prepolymer, 8 to 12 parts of long-chain alkane organic alcohol, 8 to 12 parts of multi-element organic amine, 5 to 8 parts of multi-element organic aldehyde, 1 to 3 parts of emulsifier, 0.1 to 0.2 part of defoaming agent, 0.8 to 1.6 parts of catalyst and 20 to 30 parts of deionized water, and the preparation method of the waste down feather-based prepolymer comprises the following steps: impurity removal, protein extraction and carboxyl modification. Long-chain alkane is introduced to the molecular surface of the coating as a hydrophobic group, and short-chain amino is introduced to the molecular surface of the coating as a hydrophilic group, so that the coating has the performance of preventing liquid water and resisting water vapor, and a substrate material is endowed with comprehensive waterproof performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of high value-added utilization of waste down resources and waterproof coatings, and in particular relates to a waterproof coating prepared based on waste down and a preparation method thereof. Background Art

[0002] Down in discarded down jackets is a kind of domestic waste and is often discarded. It not only brings a certain burden to the environment but also causes a waste of resources. Down comes from ducks and geese. Its main component is keratin. It is a natural biomacromolecule. The molecular chain contains rich amino groups (refer to "Research and Application of Near-Infrared Spectroscopy in Identification of Down and Feather Species, China Fiber Inspection, 2024, (12): 50-53, Sun Jin, Zhao Rui, Fang Songchen, etc.), which can be used as reactive sites to synthesize new coatings. In addition, the waterproof coatings currently on the market mainly achieve the purpose of waterproofing by introducing long-chain alkanes as hydrophobic groups on the polymer surface. China Patent Publication No. [CN119842295A] discloses a water-based epoxy back-water surface odorless waterproof coating, which achieves waterproofing by grafting silane coupling agent with epoxy resin and using long-chain alkanes as hydrophobic groups. Purpose. China Patent Publication No. [CN119823626A] discloses a waterproof coating and a preparation method thereof, which realizes the waterproofness of the base material by grafting fluorosilane onto the surface of an inorganic material and further curing it with an epoxy resin. Although the above-mentioned material is made into a waterproof coating by hydrophobic modification and coated on the base material, giving the base material good waterproof performance against liquid water, it is well known that hydrophobic materials only have a protective effect against liquid water and have almost no protection against water vapor. In reality, some equipment that needs to be waterproof, such as steel, house buildings, etc., not only need to be protected against liquid water, but also need to be protected against water vapor. Therefore, it is urgent to develop a waterproof coating that can imitate both liquid water and water vapor. Summary of the Invention

[0003] In view of the above-mentioned shortcomings, the purpose of the present invention is to provide a waterproof coating prepared based on waste down and a preparation method thereof. By using waste down as raw material, carboxyl groups are successfully grafted through the amino groups on the surface of its molecular chain, and then a long-chain alkane group is introduced into the molecular chain by esterification reaction. During the carboxyl modification process, attention should be paid to the molar ratio of carboxyl groups and amino groups, so that the molar mass of amino groups is greater than that of carboxyl groups, so that part of the amino groups in the waste down molecular chain are not modified and serve as short-chain hydrophilic groups. Finally, the aldehyde group reacts with part of the amino groups in the down molecular chain to form a network cross-linked structure with the polyorganic amine in the formula to form a coating film.

[0004] The specific technical solutions are as follows:

[0005] A waterproof coating prepared from waste down, comprising, by weight, 20-30 parts of a waste down-based prepolymer, 8-12 parts of a long-chain alkane organic alcohol, 8-12 parts of a polybasic organic amine, 5-8 parts of a polybasic organic aldehyde, 1-3 parts of an emulsifier, 0.1-0.2 parts of a defoaming agent, 0.8-1.6 parts of a catalyst, and 20-30 parts of deionized water. The preparation method of the waste down-based prepolymer comprises the following steps:

[0006] S1 impurity removal: immerse the collected waste down in a mixed solution of acetone / methanol with a mass ratio of 1:1, stir at a speed of 200-500 rpm, mix for 18-30 hours, then rinse the waste down with anhydrous ethanol, and dry in an oven at 30-40°C overnight to obtain dry and clean down;

[0007] S2 protein extraction: 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 clean down was then immersed in a mixed solution of urea / sodium metabisulfite / sodium hydroxide. The mixture was stirred at a speed of 500-800 rpm and a temperature of 80-100°C for 12-18 hours to promote protein decomposition. After the reaction was completed, the mixture was filtered through a 120-mesh stainless steel sieve, the filtrate was collected, and the waste down residue was removed by centrifugation. The centrifuged filtrate was then dialyzed to remove urea, sodium metabisulfite, and sodium hydroxide to obtain a purified protein solution. The mass ratio of the down to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:20-30.

[0008] S3 carboxyl modification: add organic aldehyde acid and dilute sulfuric acid with a concentration of 5wt% to 10wt% to the purified protein solution, adjust the pH of the mixed solution to 1 to 3, and then reflux the reaction at 80 to 90°C for 6 to 8 hours. After the reaction is completed, cool it to 25 to 30°C, add 1 mol / L sodium hydroxide solution to make the pH of the mixed solution 7 to 9, and then use dialysis to remove the salt in the mixed solution to obtain a carboxyl-modified waste down-based prepolymer.

[0009] In some embodiments, the long-chain alkane organic alcohol is selected from one or more of cetyl alcohol, octadecyl alcohol, and heneicosyl alcohol.

[0010] In some embodiments, the polyvalent organic amine is selected from one or more of hexamethylenetetramine, ethylenediamine, and hexamethylenediamine.

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

[0012] In some embodiments, the emulsifier is selected from one or more of sodium stearate, sodium stearyl glutamate, and potassium cetyl phosphate.

[0013] In some embodiments, the defoaming agent is selected from one or more of sucrose fatty acid esters and polyglycerol fatty acid esters.

[0014] In some embodiments, the catalyst is selected from one or more of antimony trioxide and tin acetate.

[0015] In some embodiments, the organic aldehyde in S3 is selected from one or more of glyoxylic acid, propionaldehyde, 3-carboxy-1-butyraldehyde, 4-carboxy-1-pentanal, and 4-carboxy-1-methyl-1-pentanal.

[0016] In some embodiments, the molar ratio of the purified protein solution to the organic aldehyde in S3 needs to be determined according to the amino concentration in the purified protein solution, so that the molar ratio of the amino group to the organic aldehyde in the purified protein solution is 1:0.4-0.6.

[0017] The present invention also provides a method for preparing the above-mentioned waterproof coating based on waste down, the preparation method comprising the following steps:

[0018] S1: In a multifunctional reactor, long-chain alkane organic alcohol, deionized water, emulsifier, and defoamer are added in sequence according to the formula weight, and then stirred at a speed of 500-1000 rpm for 10-30 minutes while introducing nitrogen to obtain an emulsion. Stirring is continued for 10-30 minutes to obtain a uniform mixed solution, and nitrogen is continued to be introduced for 5-10 minutes;

[0019] S2 adds waste down-based prepolymer, stops introducing nitrogen, heats to 120-150°C, continues stirring for 1-3 hours, adds catalyst, heats to 200-220°C to initiate esterification reaction, keeps warm for 4-8 hours, and separates the generated water vapor with a water separator;

[0020] After the reaction in S3 is completed, the temperature is lowered to 30-40°C, and polyorganic aldehydes and polyorganic amines are added in sequence, and the stirring and heat preservation reaction is continued for 3-6 hours. During this period, the generated water vapor is separated with a water separator. After the reaction is completed, deionized water is added in a formulated amount so that the viscosity of the mixed solution is 9000-12000cps / 25°C, and then the stirring is continued at a stirring speed of 800-1000 rpm for 30-60 minutes to obtain a waterproof coating prepared based on waste down.

[0021] The present invention has the following advantages:

[0022] (1) Using waste down as raw material for production is low-cost and can reduce the pollution of waste down to the environment, thus achieving high-value utilization of waste and providing a new insight into the resource utilization of waste down;

[0023] (2) The formula does not involve the use of organic solvents, and the subsequent use of the coating will not produce gases harmful to human health, which is in line with the green and environmentally friendly production concept;

[0024] (3) The present invention introduces long-chain alkanes as hydrophobic groups and short-chain amino groups as hydrophilic groups on the molecular surface of the coating, so that the coating has both liquid water resistance and water vapor resistance, giving the base material all-round waterproof properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the chemical reaction formula for the preparation process of waterproof coatings based on waste down;

[0026] Figure 2 From left to right are front scanning electron micrographs of the film-forming waterproof coatings prepared based on waste down prepared in Examples 8, 9 and 10;

[0027] Figure 3 From left to right are cross-sectional scanning electron micrographs of the films of the waterproof coatings prepared based on waste down prepared in Examples 8, 9 and 10;

[0028] Figure 4 Biodegradation test results of the polysaccharide acrylic resin prepared in Examples 12 to 14. DETAILED DESCRIPTION

[0029] 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.

[0030] Example 1

[0031] The collected waste down was immersed in an acetone / methanol mixed solution with a mass ratio of 1:1, mixed for 30 hours at a stirring speed of 200 rpm, and then the waste down was rinsed with anhydrous ethanol and dried in an oven at 30°C overnight to obtain dry and clean down; 8 mol of urea, 0.2 mol of sodium metabisulfite and 1 mol of sodium hydroxide were dissolved in 200 mL of distilled water, and then the obtained clean down was immersed in a mixed solution of urea / sodium metabisulfite / sodium hydroxide, and the mass ratio of down to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:20. The mixture was stirred at a speed of 500 rpm and a temperature of 80°C for 18 hours to promote protein decomposition. After the reaction was completed, it was filtered with a 120-mesh stainless steel mesh, the filtrate was taken, and centrifuged to remove the waste down residue. The centrifuged filtrate was then dialyzed to remove urea, sodium metabisulfite and sodium hydroxide to obtain a purified protein solution.

[0032] Example 2

[0033] The collected waste down was immersed in an acetone / methanol mixed solution with a mass ratio of 1:1, mixed for 24 hours at a stirring speed of 300 rpm, and then the waste down was rinsed with anhydrous ethanol and dried in a 35°C oven overnight to obtain dry and clean down; 8 mol of urea, 0.2 mol of sodium metabisulfite and 1 mol of sodium hydroxide were dissolved in 200 mL of distilled water, and then the obtained clean down was immersed in a mixed solution of urea / sodium metabisulfite / sodium hydroxide, and the mass ratio of down to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:25. The mixture was stirred at a speed of 800 rpm and a temperature of 90°C for 15 hours to promote protein decomposition. After the reaction was completed, it was filtered with a 120-mesh stainless steel mesh, the filtrate was taken, and centrifuged to remove the waste down residue. The centrifuged filtrate was then dialyzed to remove urea, sodium metabisulfite and sodium hydroxide to obtain a purified protein solution.

[0034] Example 3

[0035] The collected waste down was immersed in an acetone / methanol mixed solution with a mass ratio of 1:1, mixed for 18 hours at a stirring speed of 500 rpm, and then the waste down was rinsed with anhydrous ethanol and dried in a 40°C oven overnight to obtain dry and clean down; 8 mol of urea, 0.2 mol of sodium metabisulfite and 1 mol of sodium hydroxide were dissolved in 200 mL of distilled water, and then the obtained clean down was immersed in a mixed solution of urea / sodium metabisulfite / sodium hydroxide, and the mass ratio of down to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:30. The mixture was stirred at a speed of 800 rpm and a temperature of 100°C for 12 hours to promote protein decomposition. After the reaction was completed, it was filtered with a 120-mesh stainless steel mesh, the filtrate was taken, and centrifuged to remove the waste down residue. The centrifuged filtrate was then dialyzed to remove urea, sodium metabisulfite and sodium hydroxide to obtain a purified protein solution.

[0036] Example 4

[0037] The purified protein solution obtained in Example 1 was added with glyoxylic acid and 10 wt % dilute sulfuric acid, and the pH of the mixed solution was adjusted to 1. The mixture was then refluxed at 80° C. for 8 hours. After the reaction, the mixture was cooled to 30° C. and a 1 M sodium hydroxide solution was added to adjust the pH of the mixed solution to 7. The salt in the mixed solution was then removed by dialysis to obtain a carboxyl-modified waste down-based prepolymer. The molar ratio of amino groups to glyoxylic acid in the purified protein solution in this example was 1:0.4.

[0038] Example 5

[0039] The purified protein solution obtained in Example 2 was added with propionic acid and 8 wt % dilute sulfuric acid, and the pH of the mixed solution was adjusted to 2. The mixture was then refluxed at 90° C. for 7 hours. After the reaction, the mixture was cooled to 25° C. and a 1 M sodium hydroxide solution was added to adjust the pH of the mixed solution to 8. The salt in the mixed solution was then removed by dialysis to obtain a carboxyl-modified waste down-based prepolymer. The molar ratio of amino groups to propionic acid in the purified protein solution in this example was 1:0.5.

[0040] Example 6

[0041] The purified protein solution obtained in Example 3 was added with 3-carboxy-1-butyraldehyde and dilute sulfuric acid with a concentration of 10 wt%, and the pH of the mixed solution was adjusted to 3. The mixture was then refluxed at 90° C. for 6 hours. After the reaction, the mixture was cooled to 30° C. and a 1 M sodium hydroxide solution was added to adjust the pH of the mixed solution to 9. The salt in the mixed solution was then removed by dialysis to obtain a carboxyl-modified waste down-based prepolymer. The molar ratio of amino groups to 3-carboxy-1-butyraldehyde in the purified protein solution in this example was 1:0.6.

[0042] Example 7

[0043] The purified protein solutions prepared in Examples 1 to 6 were tested for amino content. 1 mL of the purified protein solutions prepared in Examples 1 to 6 were added to a ninhydrin solution for color development. The absorbance of the reaction solutions was then measured spectrophotometrically. According to the Lambert-Beer law and the standard sample, the amino content of the solutions prepared in Examples 1 to 6 was 0.89 mmol g -1 、0.92mmol g -1 、0.96mmol g -1 、0.58mmol g -1 、0.49mmol g -1 and 0.41 mmol g -1 .

[0044] The waste down-based prepolymers prepared in Examples 4-6 were tested for carboxyl content. The free carboxyl group content of the waste down-based prepolymers was determined using conductivity titration. 50 mg of the waste down-based prepolymer was added with 10 ml (0.01 M) HCl and subjected to ultrasonic treatment for 4 hours. Finally, the suspension was titrated with NaOH (0.01 M).

[0045]

[0046] Where C NaOH is the concentration of NaOH (0.01M), V NaOH is the volume of NaOH required to titrate HCl, and m is the dry weight of the waste down-based prepolymer. The results show that the free carboxyl content of the waste down-based prepolymer prepared in Examples 4, 5 and 6 is 0.24 mmol g -1 、0.42mmol g -1 and 0.45 mmol g -1 .

[0047] Example 8

[0048] like Figure 1As shown, in a multifunctional reactor, hexadecanol, deionized water, sodium stearate and sucrose fatty acid ester are added in sequence according to the formula weight, and then nitrogen is introduced and stirred at a speed of 500 rpm for 30 minutes to obtain an emulsion, which is further stirred for 30 minutes to obtain a uniform mixed solution, and nitrogen is continued to be introduced for 10 minutes; waste down-based prepolymer is added, nitrogen is stopped, the temperature is raised to 120°C, stirring is continued for 3 hours, antimony trioxide is added, the temperature is raised to 200°C to initiate esterification, and the reaction is kept warm for 8 hours, during which the water vapor generated is separated by a water separator; after the reaction is completed, the temperature is lowered to 30°C, glutaraldehyde and hexamethylenetetramine are added in sequence, and the reaction is continued to be stirred and kept warm for 6 hours, during which the water vapor generated is separated by a water separator, and after the reaction is completed, deionized water in the formula amount is added to make the viscosity of the mixed solution 9000cps / 25°C, and then stirring is continued at a stirring speed of 800 rpm for 60 minutes to obtain a waterproof coating prepared based on waste down. The prepared waterproof coating based on waste down was coated on a glass plate and cured at a temperature of 80°C and a humidity of 40-60% to form a film. The prepared film was tested by scanning electron microscopy. Figure 2 As shown in a, the surface is dense and smooth with almost no pores; the scanning electron microscope of the cross section is as follows Figure 3 As shown in a, there is no layered structure and it is almost a whole. The above results show that the waterproof coating prepared based on waste down is dense after film formation, which is beneficial to the later waterproof performance.

[0049] Table 1 Raw material ratios for synthesizing the waterproof coating prepared based on waste down in Example 8

[0050] Waste down-based prepolymer 20 servings Cetyl alcohol 8 servings Hexamethylenetetramine 8 servings Glutaraldehyde 5 servings Sodium stearate 1 serving Sucrose fatty acid esters 0.1 part Antimony trioxide 0.8 servings Deionized water 20 servings

[0051] The waste down-based prepolymer in Table 1 was prepared by the method described in Example 4.

[0052] According to GB / T 6739-1996 "Coating Hardness Pencil Test Method", the strength of the waterproof coating prepared from waste down was tested manually after film formation. The test results showed that the film strength was > B.

[0053] According to GB / T 23985-2009 "Paints and varnishes - Determination of volatile organic compound (VOC) content - Difference method", the VOC test of the waterproof coating film prepared based on waste down was carried out, and the result was VOC≤8.19g / L.

[0054] Example 9

[0055] like Figure 1As shown, in a multifunctional reactor, octadecyl alcohol, deionized water, sodium stearyl glutamate and polyglycerol fatty acid ester are added in sequence according to the formula weight, and then nitrogen is introduced and stirred at a speed of 800 rpm for 20 minutes to obtain an emulsion, which is further stirred for 20 minutes to obtain a uniform mixed solution, and nitrogen is continued to be introduced for 8 minutes; waste down-based prepolymer is added, nitrogen is stopped, the temperature is raised to 130°C, stirring is continued for 2 hours, tin acetate is added, the temperature is raised to 210°C to initiate esterification reaction, and the reaction is kept warm for 6 hours, during which the water vapor generated is separated by a water separator; after the reaction is completed, the temperature is lowered to 35°C, malondialdehyde and ethylenediamine are added in sequence, and the reaction is continued to be stirred and kept warm for 4 hours, during which the water vapor generated is separated by a water separator, and after the reaction is completed, deionized water in the formula amount is added so that the viscosity of the mixed solution is 10,000 cps / 25°C, and then stirring is continued for 45 minutes at a stirring speed of 900 rpm to obtain a waterproof coating prepared based on waste down. The prepared waterproof coating based on waste down was coated on a glass plate and cured at a temperature of 80°C and a humidity of 40-60% to form a film. The prepared film was tested by scanning electron microscopy. Figure 2 As shown in middle b, the surface is dense and smooth with almost no pores; the scanning electron microscope of the cross section is as follows Figure 3 As shown in b, there is no layered structure and it is almost a whole. The above results show that the waterproof coating prepared based on waste down is dense after film formation, which is beneficial to the later waterproof performance.

[0056] Table 2 Raw material ratios for synthesizing the waterproof coating prepared based on waste down in Example 9

[0057]

[0058]

[0059] The waste down-based prepolymer in Table 2 was prepared by the method described in Example 5.

[0060] According to GB / T 6739-1996 "Coating Hardness Pencil Test Method", the strength of the waterproof coating prepared from waste down was tested manually after film formation. The test results showed that the film strength was > B.

[0061] According to GB / T 23985-2009 "Paints and varnishes - Determination of volatile organic compound (VOC) content - Difference method", the VOC test of the waterproof coating film prepared based on waste down was carried out, and the result was VOC≤6.47g / L.

[0062] Example 10

[0063] like Figure 1As shown, in a multifunctional reactor, hexanediol, deionized water, potassium cetyl phosphate and sucrose fatty acid ester are added in sequence according to the formula weight, and then stirred at a speed of 1000 rpm for 10 minutes while introducing nitrogen to obtain an emulsion. Stirring is continued for 10 minutes to obtain a uniform mixed solution, and nitrogen is continued to be introduced for 5 minutes; waste down-based prepolymer is added, nitrogen is stopped, the temperature is raised to 150°C, stirring is continued for 1 hour, antimony trioxide is added, the temperature is raised to 220°C to initiate esterification reaction, and the reaction is kept warm for 4 hours, during which the water vapor generated is separated by a water separator; after the reaction is completed, the temperature is lowered to 40°C, succinyldialdehyde and hexamethylenediamine are added in sequence, and the reaction is continued to be stirred and kept warm for 3 hours, during which the water vapor generated is separated by a water separator. After the reaction is completed, deionized water in the formula amount is added to make the viscosity of the mixed solution 12000cps / 25°C, and then stirring is continued at a stirring speed of 1000 rpm for 30 minutes to obtain a waterproof coating prepared based on waste down. The prepared waterproof coating based on waste down was coated on a glass plate and cured at a temperature of 80°C and a humidity of 40-60% to form a film. The prepared film was tested by scanning electron microscopy. Figure 2 As shown in middle c, the surface is dense and smooth with almost no pores; the scanning electron microscope of the cross section is as follows Figure 3 As shown in c, there is no layered structure and it is almost a whole. The above results show that the waterproof coating prepared based on waste down is dense after film formation, which is beneficial to the later waterproof performance.

[0064] Table 3 Raw material ratios for synthesizing the waterproof coating prepared based on waste down in Example 10

[0065]

[0066]

[0067] The waste down-based prepolymer in Table 3 was prepared by the method described in Example 6.

[0068] According to GB / T 6739-1996 "Coating Hardness Pencil Test Method", the strength of the waterproof coating prepared from waste down was tested manually after film formation. The test results showed that the film strength was > B.

[0069] According to GB / T 23985-2009 "Paints and varnishes - Determination of volatile organic compound (VOC) content - Difference method", the VOC test of the waterproof coating film prepared based on waste down was carried out, and the result was VOC≤9.25g / L.

[0070] Test Example 11

[0071] The films made of waterproof coatings based on waste down prepared in Examples 8, 9 and 10 were tested for liquid water and water vapor protection. First, the liquid water protection was mainly tested by contact angle test. The results are as follows: Figure 4 As shown, the contact angles of the waterproof coating films prepared in Examples 8, 9, and 10 were 119.5°, 121.8°, and 122.4°, respectively, all exhibiting hydrophobicity, indicating good liquid water protection. Water vapor protection was primarily tested by water vapor transmission rate, specifically referring to the standard method ASTM F1249. The water vapor transmission rates of the waterproof coating films prepared in Examples 8, 9, and 10 were 845.9 g / (㎡·24h), 815.7 g / (㎡·24h), and 859.6 g / (㎡·24h), respectively, indicating that the waterproof coating films prepared in Examples 8, 9, and 10 had low water vapor transmission rates and good water vapor protection.

[0072] 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 waterproof coating prepared based on waste down, characterized in that: The waterproof coating prepared based on waste down is composed of 20 to 30 parts of waste down-based prepolymer, 8 to 12 parts of long-chain alkane organic alcohol, 8 to 12 parts of polybasic organic amine, 5 to 8 parts of polybasic organic aldehyde, 1 to 3 parts of emulsifier, 0.1 to 0.2 parts of defoaming agent, 0.8 to 1.6 parts of catalyst, and 20 to 30 parts of deionized water. The preparation method of the waste down-based prepolymer comprises the following steps: S1 impurity removal: immerse the collected waste down in a mixed solution of acetone / methanol with a mass ratio of 1:1, stir at a speed of 200-500 rpm, mix for 18-30 hours, then rinse the waste down with anhydrous ethanol, and dry in an oven at 30-40°C overnight to obtain dry and clean down; S2 protein extraction: 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 clean down was then immersed in a mixed solution of urea / sodium metabisulfite / sodium hydroxide. The mixture was stirred at a speed of 500-800 rpm and a temperature of 80-100°C for 12-18 hours to promote protein decomposition. After the reaction was completed, the mixture was filtered through a 120-mesh stainless steel sieve, the filtrate was collected, and the waste down residue was removed by centrifugation. The centrifuged filtrate was then dialyzed to remove urea, sodium metabisulfite, and sodium hydroxide to obtain a purified protein solution. The mass ratio of the down to the mixed solution of urea / sodium metabisulfite / sodium hydroxide was 1:20-30. S3 carboxyl modification: add organic aldehyde acid and dilute sulfuric acid with a concentration of 5wt% to 10wt% to the purified protein solution, adjust the pH of the mixed solution to 1 to 3, and then reflux the reaction at 80 to 90°C for 6 to 8 hours. After the reaction is completed, cool it to 25 to 30°C, add 1 mol / L sodium hydroxide solution to make the pH of the mixed solution 7 to 9, and then use dialysis to remove the salt in the mixed solution to obtain a carboxyl-modified waste down-based prepolymer.

2. The waterproof coating prepared from waste down according to claim 1, characterized in that: The long-chain alkane organic alcohol is selected from one or more of cetyl alcohol, octadecyl alcohol, and heneicosyl alcohol.

3. The waterproof coating prepared from waste down according to claim 1, characterized in that: The polyvalent organic amine may be one or more combinations of hexamethylenetetramine, ethylenediamine, and hexamethylenediamine.

4. The waterproof coating prepared from waste down according to claim 1, characterized in that: The polyvalent organic aldehyde is selected from one or more of glutaraldehyde, malondialdehyde, and succinaldehyde.

5. The waterproof coating prepared from waste down according to claim 1, characterized in that: The emulsifier is selected from one or more of sodium stearate, sodium stearyl glutamate and potassium cetyl phosphate.

6. The waterproof coating prepared from waste down according to claim 1, characterized in that: The defoaming agent is selected from one or more of sucrose fatty acid esters and polyglycerol fatty acid esters.

7. The waterproof coating prepared from waste down according to claim 1, characterized in that: The catalyst is selected from one or more of antimony trioxide and tin acetate.

8. The waterproof coating prepared from waste down according to claim 1, characterized in that: The organic aldehyde acid in S3 is selected from one or more of glyoxylic acid, propionaldehyde, 3-carboxy-1-butyraldehyde, 4-carboxy-1-pentanal, and 4-carboxy-1-methyl-1-pentanal.

9. The waterproof coating prepared from waste down according to claim 1, characterized in that: The molar ratio of the purified protein solution to the organic aldehyde in S3 needs to be determined according to the amino concentration in the purified protein solution, so that the molar ratio of the amino group to the organic aldehyde in the purified protein solution is 1:0.4-0.

6.

10. The method for preparing a waterproof coating based on waste down according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: S1: In a multifunctional reactor, long-chain alkane organic alcohol, deionized water, emulsifier, and defoamer are added in sequence according to the formula weight, and then stirred at a speed of 500-1000 rpm for 10-30 minutes while introducing nitrogen to obtain an emulsion. Stirring is continued for 10-30 minutes to obtain a uniform mixed solution, and nitrogen is continued to be introduced for 5-10 minutes; S2 adds waste down-based prepolymer, stops introducing nitrogen, heats to 120-150°C, continues stirring for 1-3 hours, adds catalyst, heats to 200-220°C to initiate esterification reaction, keeps warm for 4-8 hours, and separates the generated water vapor with a water separator; After the reaction in S3 is completed, the temperature is lowered to 30-40°C, and polyorganic aldehydes and polyorganic amines are added in sequence, and the stirring and heat preservation reaction is continued for 3-6 hours. During this period, the generated water vapor is separated with a water separator. After the reaction is completed, deionized water is added in a formulated amount so that the viscosity of the mixed solution is 9000-12000cps / 25°C, and then the stirring is continued at a stirring speed of 800-1000 rpm for 30-60 minutes to obtain a waterproof coating prepared based on waste down.

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