Environment-friendly anti-aging automobile repair paint and preparation method thereof

Abstract

The application relates to the paint technology field, and discloses an environment-friendly anti-aging automobile repair paint and a preparation method thereof; the operation steps are as follows: water-based polyurethane is added into deionized water and uniformly mixed; a defoaming agent, a leveling agent, an anti-aging agent and color paste are continuously stirred and uniformly mixed; and a water-based isocyanate curing agent is added to obtain the environment-friendly anti-aging automobile repair paint. In the scheme, the lignin is introduced into the water-based polyurethane and the anti-aging agent respectively, the dispersity of the lignin in the environment-friendly anti-aging automobile repair paint is improved, and the anti-aging property and the environmental protection property of the automobile repair paint can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to an environmentally friendly and aging-resistant automotive repair paint and its preparation method. Background Technology

[0002] With the advancement and development of technology, the use of automobiles continues to grow, leading to an increasing demand for paint damage repair. However, traditional automotive repair paints have many shortcomings. On the one hand, traditional products are mostly solvent-based coatings, which emit large amounts of volatile organic compounds (VOCs), polluting the environment and harming the health of workers. On the other hand, their aging resistance is poor, and after repair, they are easily corroded by environmental factors such as ultraviolet rays, thus affecting the gloss of the automotive repair paint.

[0003] In summary, developing an environmentally friendly and age-resistant automotive repair paint is of great significance in order to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide an environmentally friendly and aging-resistant automotive repair paint and its preparation method, so as to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An environmentally friendly and age-resistant automotive repair paint, wherein the raw materials of the environmentally friendly and age-resistant automotive repair paint include the following components: by weight, 100 parts waterborne polyurethane, 2-4 parts anti-aging agent, 13-18 parts waterborne isocyanate curing agent, 0.2-0.6 parts defoamer, 0.4-0.8 parts leveling agent, 5-15 parts color paste, and 40-60 parts deionized water.

[0007] In a more optimized form, the raw materials of the waterborne polyurethane and the anti-aging agent both include aminophenyl sulfone modified lignin; the aminophenyl sulfone modified lignin is prepared by a Michael addition reaction of vinyl lignin and 4,4'-diaminodiphenyl sulfone in a mass ratio of 1:(2~4).

[0008] A more optimized method for preparing the aminophenyl sulfone modified lignin is as follows: (1) lignin is modified with acryloyl chloride to obtain vinyl lignin, and the vinyl lignin is dispersed in N,N-dimethylformamide to obtain a lignin solution; (2) under a protective gas atmosphere, 4,4'-diaminodiphenyl sulfone is added to N,N-dimethylformamide and mixed evenly, the temperature is raised to 50~60℃, the lignin solution is added dropwise and stirred evenly; the temperature is raised to 80~90℃ and the reaction is stirred to obtain aminophenyl sulfone modified lignin.

[0009] The method for preparing vinyl lignin in the scheme is as follows: 10-15 parts of lignin are added to 60-70 parts of N,N-dimethylformamide and stirred evenly. The mixture is heated to 90-100℃ and stirred for 20-30 minutes. The mixture is then cooled to 25-30℃, and 5-7 parts of acryloyl chloride and 1-2 parts of triethylamine are added dropwise. The mixture is stirred for 10-12 hours, filtered, washed, and dried to obtain vinyl lignin.

[0010] In this process, the phenolic hydroxyl groups on lignin undergo a nucleophilic substitution reaction with acryloyl chloride to obtain vinyl lignin; the amino group on 4,4'-diaminodiphenyl sulfone undergoes a Michael addition reaction with the double bond on vinyl lignin to obtain aminophenyl sulfone-modified lignin.

[0011] A more optimized method for preparing the waterborne polyurethane is as follows: (1) Under a protective gas atmosphere, aminophenyl sulfone-modified lignin is added to N,N-dimethylformamide and mixed evenly. The temperature is raised to 50~60℃, and diethyl maleate is added dropwise and stirred evenly. The temperature is raised to 80~90℃ and stirred to react, and polyaspartic acid ester is obtained.

[0012] (2) Under a protective gas atmosphere, polytetrahydrofuran glycol is dehydrated, and 2,2-dimethylolpropionic acid, 4,4'-diisocyanate dicyclohexylmethane, and dibutyltin dilaurate are added at 70~80℃ and reacted; the temperature is lowered to 60~70℃, acetone and polyaspartic acid ester are added and reacted; 1,4-butanediol is added and reacted; the temperature is lowered, triethylamine is added to neutralize, deionized water and emulsifier are added, stirred, acetone is evaporated by rotary evaporation, and deionized water is added again to dilute and obtain waterborne polyurethane.

[0013] In a more optimized form, the mass ratio of aminophenyl sulfone-modified lignin to diethyl maleate in the raw material of the polyaspartic acid ester is 1:(0.4~0.7).

[0014] The raw materials of the waterborne polyurethane include the following components by mass: 90 parts polytetrahydrofuran diol, 13-17 parts 2,2-dimethylolpropionic acid, 70-85 parts 4,4'-diisocyanate dicyclohexylmethane, 0.07-0.12 parts dibutyltin dilaurate, 15-25 parts polyaspartic acid ester, 2-5 parts 1,4-butanediol, 15-22 parts triethylamine, and 1-3 parts emulsifier.

[0015] Ideally, the solid content of the waterborne polyurethane is 25-35 wt%.

[0016] In the proposed method, the -NCO content is determined by di-n-butylamine titration, and the temperature is lowered to neutralize the -NCO after confirming that it has been completely consumed.

[0017] The lignin molecular chain modified with amino sulfone contains active amino groups, and diethyl maleate contains conjugated double bonds. Under the conditions of premixing at 50~60℃ and reacting at 80~90℃, the two undergo a Michael addition reaction to generate polyaspartic acid ester.

[0018] Polytetrahydrofurandiol, 2,2-dimethylolpropionic acid, and 4,4'-diisocyanate dicyclohexylmethane undergo an addition reaction of hydroxyl groups with isocyanates under the action of dibutyltin dilaurate, generating a polyurethane prepolymer with terminal -NCO groups. Polyaspartic acid ester is added to the polyurethane prepolymer, and the active amine groups on it undergo an addition reaction with the terminal -NCO groups of the prepolymer to form urea bonds. 1,4-Butanediol is added for hydroxyl end-capping, and triethylamine is added to neutralize the carboxyl groups introduced by 2,2-dimethylolpropionic acid. After stirring with deionized water and emulsifier, a hydroxyl-terminated waterborne polyurethane is obtained.

[0019] A more optimized method for preparing the anti-aging agent is as follows: aminophenyl sulfone-modified lignin and aminated nano-titanium dioxide are dispersed in acetone, tea polyphenol-based epoxy monomers are added and mixed evenly, and stirred at 80~90℃ for 5~7 hours to obtain the anti-aging agent.

[0020] In a more optimized form, the raw materials of the anti-aging agent include the following components: by mass parts, 4-7 parts of aminophenyl sulfone modified lignin, 2-5 parts of aminated nano titanium dioxide, and 1-3 parts of tea polyphenol-based epoxy monomer.

[0021] In this method, the epoxy groups on the polyphenolic epoxy monomer react with the amino groups on the lignin modified with amino sulfone and the amino groups on the aminated nano-titanium dioxide to obtain an anti-aging agent.

[0022] The preparation method of aminated nano-titanium dioxide is as follows: 4-7 parts of γ-aminopropyltriethoxysilane are added to hydrochloric acid aqueous solution with pH 3-4, stirred for 40-60 minutes, 3-5 parts of nano-titanium dioxide are added and ultrasonically dispersed, stirred at 70-80℃ for 2-3 hours, washed and dried to obtain aminated nano-titanium dioxide.

[0023] The preparation method of tea polyphenol-based epoxy monomer is as follows: 3-5 parts of tea polyphenols, 10-13 parts of epichlorohydrin, and 40-60 parts of deionized water are mixed evenly, 2-4 parts of sodium hydroxide are added, the mixture is stirred evenly, the temperature is raised to 80-95℃, the mixture is stirred and reacted for 5-6 hours, cooled to room temperature, and then allowed to stand overnight in an ice-water bath. The supernatant is removed, and the mixture is washed and dried to obtain the tea polyphenol-based epoxy monomer.

[0024] A method for preparing an environmentally friendly and aging-resistant automotive repair paint includes the following steps:

[0025] Waterborne polyurethane is added to deionized water and mixed evenly; defoamer, leveling agent, anti-aging agent and color paste are added and stirred evenly; waterborne isocyanate curing agent is added to obtain environmentally friendly and aging-resistant automotive repair paint.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] This solution introduces lignin into environmentally friendly and age-resistant automotive repair paint; however, direct mixing can easily lead to agglomeration, affecting its application in automotive repair paint. In this solution, lignin is introduced into waterborne polyurethane and anti-aging agents respectively, which improves its dispersibility in environmentally friendly and age-resistant automotive repair paint, while effectively enhancing the aging resistance and environmental friendliness of automotive repair paint.

[0028] However, relying solely on lignin to enhance the aging resistance of automotive repair paint has limited effectiveness. To further improve the aging resistance of automotive repair paint, the proposed solution involves introducing amino groups onto lignin using 4,4'-diaminodiphenyl sulfone, resulting in aminophenyl sulfone-modified lignin. 4,4'-diaminodiphenyl sulfone can improve stability and UV resistance. However, both waterborne polyurethane and anti-aging agents contain rigid aminophenyl sulfone-modified lignin. Directly introducing aminophenyl sulfone-modified lignin into waterborne polyurethane, in synergy with rigid anti-aging agents, increases the rigidity of the automotive repair paint after curing, thus affecting its adhesion. To address this issue, the proposed solution further introduces diethyl maleate to improve flexibility, preparing polyaspartic acid ester, which alleviates the rigidity introduced by aminophenyl sulfone-modified lignin, thereby improving the adhesion of the environmentally friendly and aging-resistant automotive repair paint.

[0029] In this scheme, the secondary and primary amines on polyaspartic acid ester react with the isocyanate groups in the waterborne polyurethane system to obtain a waterborne polyurethane containing a polyurea structure. The polyurea structure and aminophenyl sulfone-modified lignin work synergistically to greatly improve the aging resistance of the waterborne polyurethane, thereby enhancing the gloss of the environmentally friendly and aging-resistant automotive repair paint.

[0030] To further improve the gloss of environmentally friendly and age-resistant automotive repair paint, nano-titanium dioxide is used as an anti-aging agent and added to the paint. However, it is prone to peeling off during long-term use, affecting the gloss of the paint. To improve the compatibility of nano-titanium dioxide with the components in the automotive repair paint without affecting its anti-aging properties, the proposed solution involves reacting the epoxy groups on the polyphenol-based epoxy monomers with the amino groups of lignin modified with aminophenyl sulfone and amino-modified nano-titanium dioxide to obtain the anti-aging agent.

[0031] Among them, aminophenyl sulfone-modified lignin can improve the interfacial compatibility between anti-aging agents and waterborne polyurethane, and tea polyphenol-based epoxy monomers can improve the dispersion of anti-aging agents and enhance the interfacial bonding between automotive repair paint and substrate. The three work synergistically to effectively improve the aging resistance of automotive repair paint, thereby enhancing the gloss of automotive repair paint; however, the anti-aging agent has high rigidity, and excessive addition will lead to reduced toughness and affect the adhesion of automotive repair paint. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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.

[0033] In the following specific embodiments, "parts" refers to parts by weight. It should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: diethyl maleate (CAS number 141-05-9); 4,4'-diaminodiphenyl sulfone (CAS number 80-08-0); lignin is alkaline lignin; acryloyl chloride (CAS number 814-68-6); nano-titanium dioxide with an average particle size of 50 nm; γ-aminopropyltriethoxysilane (CAS number 919-30-2); polytetrahydrofuran diol (CAS number 25190-06-1), with a molecular weight of [missing information]. 2000; CAS number for 2,2-dimethylolpropionic acid is 4767-03-7; CAS number for 4,4'-diisocyanate dicyclohexylmethane is 5124-30-1; CAS number for dibutyltin dilaurate is 77-58-7; CAS number for triethylamine is 121-44-8; CAS number for epichlorohydrin is 106-89-8; CAS number for tea polyphenols is 84650-60-2; defoamer is BYK-024; leveling agent is BYK-33; water-based isocyanate curing agent is DB82655; color paste is water-based resin-free nano color paste.

[0034] The preparation method of aminated nano-titanium dioxide in the scheme is as follows: 7 parts of γ-aminopropyltriethoxysilane are added to hydrochloric acid aqueous solution with pH 4, stirred for 40 minutes, 4 parts of nano-titanium dioxide are added and ultrasonically dispersed, stirred at 70°C for 3 hours, washed and dried to obtain aminated nano-titanium dioxide.

[0035] The preparation method of tea polyphenol-based epoxy monomer is as follows: 5 parts of tea polyphenol, 12 parts of epichlorohydrin and 60 parts of deionized water are mixed evenly, 3 parts of sodium hydroxide are added, the mixture is stirred evenly, the temperature is raised to 90℃, the mixture is stirred and reacted for 6 hours, cooled to room temperature, and then left to stand overnight in an ice-water bath. The supernatant is removed, and the mixture is washed and dried to obtain tea polyphenol-based epoxy monomer.

[0036] Example 1: A method for preparing an environmentally friendly and aging-resistant automotive repair paint, comprising the following steps:

[0037] Pre-preparation: The preparation method of aminosulfone modified lignin is as follows: (1) 10 parts of lignin are added to N,N-dimethylformamide and stirred evenly. The temperature is raised to 90℃ and stirred for 20 minutes. The temperature is lowered to 25℃, 5 parts of acryloyl chloride and 1 part of triethylamine are added dropwise and stirred for 12 hours. The mixture is filtered, washed and dried to obtain vinyl lignin. The vinyl lignin is dispersed in N,N-dimethylformamide to obtain a lignin solution. (2) Under a protective gas atmosphere, 4,4'-diaminodiphenyl sulfone is added to N,N-dimethylformamide and mixed evenly. The temperature is raised to 55℃, and the lignin solution is added dropwise and stirred evenly. The temperature is raised to 80℃ and stirred for 3 hours to obtain aminosulfone modified lignin. The mass ratio of vinyl lignin to 4,4'-diaminodiphenyl sulfone is 1:3.

[0038] The preparation method of waterborne polyurethane is as follows: (1) Under a protective gas atmosphere (nitrogen), aminosulfone-modified lignin is added to N,N-dimethylformamide and mixed evenly. The temperature is raised to 55°C, and diethyl maleate is added dropwise and stirred evenly. The temperature is raised to 80°C and stirred for 4 hours to obtain polyaspartic acid ester. The mass ratio of aminosulfone-modified lignin to diethyl maleate is 1:0.5.

[0039] (2) Under a protective gas atmosphere (nitrogen), 90 parts of polytetrahydrofuran glycol were heated to 120°C and dehydrated under vacuum for 1.2 hours; at 80°C, 15 parts of 2,2-dimethylolpropionic acid, 85 parts of 4,4'-diisocyanate dicyclohexylmethane, and 0.1 parts of dibutyltin dilaurate were added, and the reaction was carried out for 2 hours; the temperature was lowered to 67°C, 50 parts of acetone and 25 parts of polyaspartic acid ester were added, and the reaction was carried out for 3.5 hours; 1,4-butanediol was added and the reaction was carried out for 2 hours; the temperature was lowered to 40°C, 20 parts of triethylamine were added for neutralization, deionized water and 2 parts of emulsifier (sodium N-(2-aminoethyl)aminoethane sulfonate) were added, and the mixture was stirred at 1000 rpm. The acetone was evaporated off by rotary evaporation, and deionized water was added again for dilution to obtain waterborne polyurethane; the solid content of the waterborne polyurethane was 30 wt%.

[0040] The preparation method of the anti-aging agent is as follows: 7 parts of aminophenyl sulfone modified lignin and 2 parts of aminated nano titanium dioxide are dispersed in acetone, 2 parts of tea polyphenol-based epoxy monomer are added and mixed evenly, stirred at 90°C for 6 hours, filtered, washed and dried to obtain the anti-aging agent.

[0041] Add 100 parts of waterborne polyurethane to 50 parts of deionized water and mix evenly; add 0.4 parts of defoamer, 0.5 parts of leveling agent, 2 parts of anti-aging agent, and 6 parts of color paste and continue stirring evenly; add 17 parts of waterborne isocyanate curing agent to obtain environmentally friendly and age-resistant automotive repair paint.

[0042] Example 2: A method for preparing an environmentally friendly and aging-resistant automotive repair paint, comprising the following steps:

[0043] Pre-preparation: The preparation method of aminosulfone modified lignin is as follows: (1) 10 parts of lignin are added to N,N-dimethylformamide and stirred evenly. The temperature is raised to 90℃ and stirred for 20 minutes. The temperature is lowered to 25℃, 5 parts of acryloyl chloride and 1 part of triethylamine are added dropwise and stirred for 12 hours. The mixture is filtered, washed and dried to obtain vinyl lignin. The vinyl lignin is dispersed in N,N-dimethylformamide to obtain a lignin solution. (2) Under a protective gas atmosphere, 4,4'-diaminodiphenyl sulfone is added to N,N-dimethylformamide and mixed evenly. The temperature is raised to 55℃, and the lignin solution is added dropwise and stirred evenly. The temperature is raised to 90℃ and stirred for 12 hours to obtain aminosulfone modified lignin. The mass ratio of vinyl lignin to 4,4'-diaminodiphenyl sulfone is 1:3.

[0044] The preparation method of waterborne polyurethane is as follows: (1) Under a protective gas atmosphere, aminosulfone-modified lignin is added to N,N-dimethylformamide and mixed evenly. The temperature is raised to 55°C, and diethyl maleate is added dropwise and stirred evenly. The temperature is raised to 80°C and stirred for 4 hours to obtain polyaspartic acid ester. The mass ratio of aminosulfone-modified lignin to diethyl maleate is 1:0.5.

[0045] (2) Under a protective gas atmosphere, 90 parts of polytetrahydrofuran diol were heated to 120°C and vacuum dehydrated for 1.2 hours; at 80°C, 15 parts of 2,2-dimethylolpropionic acid, 85 parts of 4,4'-diisocyanate dicyclohexylmethane, and 0.1 parts of dibutyltin dilaurate were added, and the reaction was carried out for 2 hours; the temperature was lowered to 67°C, 50 parts of acetone and 25 parts of polyaspartic acid ester were added, and the reaction was carried out for 3.5 hours; 1,4-butanediol was added and the reaction was carried out for 2 hours; the temperature was lowered to 40°C, 20 parts of triethylamine were added for neutralization, deionized water and 2 parts of emulsifier (sodium N-(2-aminoethyl)aminoethane sulfonate) were added, and the mixture was stirred at 1000 rpm. The acetone was evaporated off by rotary evaporation, and deionized water was added again for dilution to obtain waterborne polyurethane; the solid content of the waterborne polyurethane was 30 wt%.

[0046] The preparation method of the anti-aging agent is as follows: 7 parts of aminophenyl sulfone modified lignin and 2 parts of aminated nano titanium dioxide are dispersed in acetone, 2 parts of tea polyphenol-based epoxy monomer are added and mixed evenly, stirred at 90°C for 6 hours, filtered, washed and dried to obtain the anti-aging agent.

[0047] Add 100 parts of waterborne polyurethane to 50 parts of deionized water and mix evenly; add 0.4 parts of defoamer, 0.5 parts of leveling agent, 2.5 parts of anti-aging agent, and 6 parts of color paste and continue stirring evenly; add 17 parts of waterborne isocyanate curing agent to obtain environmentally friendly and age-resistant automotive repair paint.

[0048] Example 3: A method for preparing an environmentally friendly and aging-resistant automotive repair paint, comprising the following steps:

[0049] Pre-preparation: The preparation method of aminosulfone modified lignin is as follows: (1) 10 parts of lignin are added to N,N-dimethylformamide and stirred evenly. The temperature is raised to 90℃ and stirred for 20 minutes. The temperature is lowered to 25℃, 5 parts of acryloyl chloride and 1 part of triethylamine are added dropwise and stirred for 12 hours. The mixture is filtered, washed and dried to obtain vinyl lignin. The vinyl lignin is dispersed in N,N-dimethylformamide to obtain a lignin solution. (2) Under a protective gas atmosphere, 4,4'-diaminodiphenyl sulfone is added to N,N-dimethylformamide and mixed evenly. The temperature is raised to 55℃, and the lignin solution is added dropwise and stirred evenly. The temperature is raised to 90℃ and stirred for 12 hours to obtain aminosulfone modified lignin. The mass ratio of vinyl lignin to 4,4'-diaminodiphenyl sulfone is 1:3.

[0050] The preparation method of waterborne polyurethane is as follows: (1) Under a protective gas atmosphere, aminosulfone-modified lignin is added to N,N-dimethylformamide and mixed evenly. The temperature is raised to 55°C, and diethyl maleate is added dropwise and stirred evenly. The temperature is raised to 80°C and stirred for 4 hours to obtain polyaspartic acid ester. The mass ratio of aminosulfone-modified lignin to diethyl maleate is 1:0.5.

[0051] (2) Under a protective gas atmosphere, 90 parts of polytetrahydrofuran diol were heated to 120°C and vacuum dehydrated for 1.2 hours; at 80°C, 15 parts of 2,2-dimethylolpropionic acid, 85 parts of 4,4'-diisocyanate dicyclohexylmethane, and 0.1 parts of dibutyltin dilaurate were added, and the reaction was carried out for 2 hours; the temperature was lowered to 67°C, 50 parts of acetone and 25 parts of polyaspartic acid ester were added, and the reaction was carried out for 3.5 hours; 1,4-butanediol was added and the reaction was carried out for 2 hours; the temperature was lowered to 40°C, 20 parts of triethylamine were added for neutralization, deionized water and 2 parts of emulsifier (sodium N-(2-aminoethyl)aminoethane sulfonate) were added, and the mixture was stirred at 1000 rpm. The acetone was evaporated off by rotary evaporation, and deionized water was added again for dilution to obtain waterborne polyurethane; the solid content of the waterborne polyurethane was 30 wt%.

[0052] The preparation method of the anti-aging agent is as follows: 7 parts of aminophenyl sulfone modified lignin and 2 parts of aminated nano titanium dioxide are dispersed in acetone, 2 parts of tea polyphenol-based epoxy monomer are added and mixed evenly, stirred at 90°C for 6 hours, filtered, washed and dried to obtain the anti-aging agent.

[0053] Add 100 parts of waterborne polyurethane to 50 parts of deionized water and mix evenly; add 0.4 parts of defoamer, 0.5 parts of leveling agent, 4 parts of anti-aging agent, and 6 parts of color paste and continue stirring evenly; add 17 parts of waterborne isocyanate curing agent to obtain environmentally friendly and age-resistant automotive repair paint.

[0054] Comparative Example 1 is based on Example 3, but without the introduction of polyaspartic ester into the waterborne polyurethane; the remaining operating steps are the same.

[0055] Pre-preparation: The waterborne polyurethane was prepared as follows: Under a protective gas atmosphere, 90 parts of polytetrahydrofuran glycol were heated to 120°C and vacuum dehydrated for 1.2 hours; at 80°C, 15 parts of 2,2-dimethylolpropionic acid, 85 parts of 4,4'-diisocyanate dicyclohexylmethane, and 0.1 parts of dibutyltin dilaurate were added, and the reaction was carried out for 2 hours; the temperature was lowered to 67°C, 50 parts of acetone and 25 parts of polyaspartic acid ester were added, and the reaction was carried out for 3.5 hours; 1,4-butanediol was added and the reaction was carried out for 2 hours; the temperature was lowered to 40°C, 20 parts of triethylamine were added for neutralization, deionized water and 2 parts of emulsifier (sodium N-(2-aminoethyl)aminoethane sulfonate) were added, and the mixture was stirred at 1000 rpm. Acetone was evaporated off by rotary evaporation, and deionized water was added again for dilution to obtain the waterborne polyurethane; the solid content of the waterborne polyurethane was 30 wt%.

[0056] Add 100 parts of waterborne polyurethane to 50 parts of deionized water and mix evenly; add 0.4 parts of defoamer, 0.5 parts of leveling agent, 4 parts of anti-aging agent, and 6 parts of color paste and continue stirring evenly; add 17 parts of waterborne isocyanate curing agent to obtain environmentally friendly and age-resistant automotive repair paint.

[0057] Comparative Example 2 is based on Example 3, except that polyaspartic acid ester is replaced with aminophenyl sulfone-modified lignin; the remaining operating steps are the same.

[0058] Pre-preparation: The preparation method of aminosulfone modified lignin is as follows: (1) 10 parts of lignin are added to N,N-dimethylformamide and stirred evenly. The temperature is raised to 90℃ and stirred for 20 minutes. The temperature is lowered to 25℃, 5 parts of acryloyl chloride and 1 part of triethylamine are added dropwise and stirred for 12 hours. The mixture is filtered, washed and dried to obtain vinyl lignin. The vinyl lignin is dispersed in N,N-dimethylformamide to obtain a lignin solution. (2) Under a protective gas atmosphere, 4,4'-diaminodiphenyl sulfone is added to N,N-dimethylformamide and mixed evenly. The temperature is raised to 55℃, and the lignin solution is added dropwise and stirred evenly. The temperature is raised to 90℃ and stirred for 12 hours to obtain aminosulfone modified lignin. The mass ratio of vinyl lignin to 4,4'-diaminodiphenyl sulfone is 1:3.

[0059] The preparation method of waterborne polyurethane is as follows: Under a protective gas atmosphere, 90 parts of polytetrahydrofuran glycol are heated to 120°C and vacuum dehydrated for 1.2 hours; at 80°C, 15 parts of 2,2-dimethylolpropionic acid, 85 parts of 4,4'-diisocyanate dicyclohexylmethane, and 0.1 parts of dibutyltin dilaurate are added, and the reaction is carried out for 2 hours; the temperature is lowered to 67°C, 50 parts of acetone and 25 parts of aminophenyl sulfone-modified lignin are added, and the reaction is carried out for 3.5 hours; 1,4-butanediol is added and the reaction is carried out for 2 hours; the temperature is lowered to 40°C, 20 parts of triethylamine are added for neutralization, deionized water and 2 parts of emulsifier (sodium N-(2-aminoethyl)aminoethane sulfonate) are added, and the mixture is stirred at 1000 rpm. Acetone is evaporated off by rotary evaporation, and deionized water is added again for dilution to obtain waterborne polyurethane; the solid content of the waterborne polyurethane is 30 wt%.

[0060] The preparation method of the anti-aging agent is as follows: 7 parts of aminophenyl sulfone modified lignin and 2 parts of aminated nano titanium dioxide are dispersed in acetone, 2 parts of tea polyphenol-based epoxy monomer are added and mixed evenly, stirred at 90°C for 6 hours, filtered, washed and dried to obtain the anti-aging agent.

[0061] Add 100 parts of waterborne polyurethane to 50 parts of deionized water and mix evenly; add 0.4 parts of defoamer, 0.5 parts of leveling agent, 4 parts of anti-aging agent, and 6 parts of color paste and continue stirring evenly; add 17 parts of waterborne isocyanate curing agent to obtain environmentally friendly and age-resistant automotive repair paint.

[0062] Comparative Example 3 is based on Example 3, except that 4,4'-diaminodiphenyl sulfone is replaced with 4,4'-diaminodicyclohexylmethane, and the other operating steps are the same;

[0063] Pre-preparation: The preparation method of aminosulfone modified lignin is as follows: (1) 10 parts of lignin are added to N,N-dimethylformamide and stirred evenly. The temperature is raised to 90℃ and stirred for 20 minutes. The temperature is lowered to 25℃, 5 parts of acryloyl chloride and 1 part of triethylamine are added dropwise and stirred for 12 hours. The mixture is filtered, washed and dried to obtain vinyl lignin. The vinyl lignin is dispersed in N,N-dimethylformamide to obtain a lignin solution. (2) Under a protective gas atmosphere, 4,4'-diaminodicyclohexylmethane is added to N,N-dimethylformamide and mixed evenly. The temperature is raised to 55℃, and the lignin solution is added dropwise and stirred evenly. The temperature is raised to 90℃ and stirred for 14 hours to obtain aminosulfone modified lignin. The mass ratio of vinyl lignin to 4,4'-diaminodicyclohexylmethane is 1:3.

[0064] Add 100 parts of waterborne polyurethane to 50 parts of deionized water and mix evenly; add 0.4 parts of defoamer, 0.5 parts of leveling agent, 4 parts of anti-aging agent, and 6 parts of color paste and continue stirring evenly; add 17 parts of waterborne isocyanate curing agent to obtain environmentally friendly and age-resistant automotive repair paint.

[0065] Comparative Example 4 is based on Example 3, but without the introduction of tea polyphenols. Aminated nano-titanium dioxide is replaced with epoxy-based nano-titanium dioxide, and the other operation steps are the same.

[0066] Pre-preparation: 7 parts of γ-glycidoxypropyltrimethoxysilane were added to 40 parts of hydrochloric acid aqueous solution with pH 4, stirred for 40 minutes, 5 parts of nano-titanium dioxide were added and ultrasonically dispersed, heated to 70℃ and stirred for 3 hours, washed and dried to obtain epoxy-modified nano-titanium dioxide.

[0067] The preparation method of the anti-aging agent is as follows: 7 parts of aminophenyl sulfone modified lignin and 2 parts of epoxy-modified nano titanium dioxide are dispersed in acetone, mixed evenly, stirred at 90°C for 5 hours, filtered, washed and dried to obtain the anti-aging agent.

[0068] Add 100 parts of waterborne polyurethane to 50 parts of deionized water and mix evenly; add 0.4 parts of defoamer, 0.5 parts of leveling agent, 4 parts of anti-aging agent, and 6 parts of color paste and continue stirring evenly; add 17 parts of waterborne isocyanate curing agent to obtain environmentally friendly and age-resistant automotive repair paint.

[0069] Testing: The environmentally friendly and aging-resistant automotive repair paints prepared in Examples 1-3 and Comparative Examples 1-4 were coated on metal plates and cured to obtain an environmentally friendly and aging-resistant automotive repair paint film.

[0070] (1) The adhesion of Examples 1-3 and Comparative Examples 1-4 was tested according to GB / T9286-1998;

[0071] (2) The gloss of Example 3 and Comparative Examples 1-4 were aged under a xenon lamp for 400 hours; the gloss of 20° before and after aging was tested according to GB / T9754-2007, and the gloss loss rate (%) was calculated.

[0072] Table 1

[0073]

[0074] Conclusions: Comparative Example 1, based on Example 3, did not introduce polyaspartic acid ester into the waterborne polyurethane; this resulted in a decrease in the aging resistance of the waterborne polyurethane, thus leading to a decline in the performance of the environmentally friendly and aging-resistant automotive repair paint. Comparative Example 2, based on Example 3, replaced polyaspartic acid ester with aminophenyl sulfone-modified lignin; this increased the rigidity of the cured environmentally friendly and aging-resistant automotive repair paint, leading to reduced adhesion and increased susceptibility to cracking after aging, thus resulting in a decrease in gloss. Comparative Example 3, based on Example 3, replaced 4,4'-diaminodiphenyl sulfone with 4,4'-diaminodicyclohexylmethane; the benzene ring structure on 4,4'-diaminodiphenyl sulfone can improve the aging resistance of the waterborne polyurethane, thus leading to a decline in performance. Comparative Example 4, based on Example 3, did not introduce tea polyphenols, and replaced aminated nano-titanium dioxide with epoxy-modified nano-titanium dioxide; this resulted in a decrease in both the adhesion and aging resistance of the environmentally friendly and aging-resistant automotive repair paint.

[0075] Test Experiment 2: The VOC content (g / L) of Example 3 was tested according to GB / T23986-2009; the impact resistance (cm) of Example 3 was tested according to GBT1732-1993.

[0076] Table 2

[0077]

[0078] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. An environmentally friendly and aging-resistant automotive repair paint, characterized in that: The raw materials of the environmentally friendly and aging-resistant automotive repair paint include the following components: by weight, 100 parts waterborne polyurethane, 2-4 parts anti-aging agent, 13-18 parts waterborne isocyanate curing agent, 0.2-0.6 parts defoamer, 0.4-0.8 parts leveling agent, 5-15 parts color paste, and 40-60 parts deionized water; The preparation method of the waterborne polyurethane is as follows: (1) Under a protective gas atmosphere, aminophenyl sulfone modified lignin is added to N,N-dimethylformamide and mixed evenly. The temperature is raised to 50~60℃, and diethyl maleate is added dropwise and stirred evenly. The temperature is raised to 80~90℃ and stirred to react, and polyaspartic acid ester is obtained. (2) Under a protective gas atmosphere, polytetrahydrofuran glycol is dehydrated, and 2,2-dimethylolpropionic acid, 4,4'-diisocyanate dicyclohexylmethane, and dibutyltin dilaurate are added at 70~80℃ and reacted; the temperature is lowered to 60~70℃, acetone and polyaspartic acid ester are added and reacted; 1,4-butanediol is added and reacted; the temperature is lowered, triethylamine is added to neutralize, deionized water and emulsifier are added, stirred, acetone is evaporated off by rotary evaporation, and deionized water is added again to dilute and obtain waterborne polyurethane; The method for preparing the anti-aging agent is as follows: by mass fraction, 4-7 parts of aminophenyl sulfone modified lignin and 2-5 parts of aminated nano titanium dioxide are dispersed in acetone, and 1-3 parts of tea polyphenol-based epoxy monomer are added and mixed evenly. The mixture is stirred at 80-90°C for 5-7 hours to obtain the anti-aging agent. The preparation method of the aminophenyl sulfone modified lignin is as follows: (1) Acryloyl chloride is used to modify lignin to obtain vinyl lignin, and the vinyl lignin is dispersed in N,N-dimethylformamide to obtain a lignin solution; (2) Under a protective gas atmosphere, 4,4'-diaminodiphenyl sulfone is added to N,N-dimethylformamide and mixed evenly, the temperature is raised to 50~60℃, the lignin solution is added dropwise and stirred evenly; the temperature is raised to 80~90℃ and stirred to react to obtain aminophenyl sulfone modified lignin.

2. The environmentally friendly and aging-resistant automotive repair paint according to claim 1, characterized in that: The aminophenyl sulfone modified lignin was prepared by a Michael addition reaction of vinyl lignin and 4,4'-diaminodiphenyl sulfone in a mass ratio of 1:(2~4).

3. The environmentally friendly and aging-resistant automotive repair paint according to claim 1, characterized in that: In the raw materials of the polyaspartic acid ester, the mass ratio of aminophenyl sulfone-modified lignin to diethyl maleate is 1:(0.4~0.7). The raw materials of the waterborne polyurethane include the following components by mass: 90 parts polytetrahydrofuran diol, 13-17 parts 2,2-dimethylolpropionic acid, 70-85 parts 4,4'-diisocyanate dicyclohexylmethane, 0.07-0.12 parts dibutyltin dilaurate, 15-25 parts polyaspartic acid ester, 2-5 parts 1,4-butanediol, 15-22 parts triethylamine, and 1-3 parts emulsifier.

4. The environmentally friendly and aging-resistant automotive repair paint according to claim 1, characterized in that: The solid content of the waterborne polyurethane is 25~35wt%.

5. A method for preparing an environmentally friendly and aging-resistant automotive repair paint according to any one of claims 1 to 4, characterized in that: The following steps are included: Waterborne polyurethane is added to deionized water and mixed evenly; defoamer, leveling agent, anti-aging agent and color paste are added and stirred evenly; waterborne isocyanate curing agent is added to obtain environmentally friendly and aging-resistant automotive repair paint.

Images