A water-based primer resin, a water-based primer paint, and a method for preparing the same.

Abstract

A water-based primer resin, a water-based primer paint, and their preparation method are disclosed, relating to the field of primer paint technology, which solves the problems of environmental pollution and quality defects caused by the need for flame treatment in existing primers. Chlorinated polypropylene is added to an organic solvent and heated to completely dissolve, yielding chlorinated polypropylene solution A. A soft monomer, a hard monomer, and (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide are added to the organic solvent and stirred to obtain grafting solution B. Benzoyl peroxide is dissolved in the organic solvent to obtain initiator solution C. Under nitrogen protection, A and B are mixed and heated to 60-80°C, then C is added dropwise. After the reaction is complete, the solvent is removed under reduced pressure to obtain an intermediate. Acetone, diisocyanate, carbon dioxide-based polyol, and dimethylolpropionic acid are added to the intermediate for reaction, followed by the addition of butanediol to continue the reaction. After cooling, deionized water and triethylamine are added. After the reaction is complete, the solvent is removed to obtain the water-based primer resin.

Description

Technical Field

[0001] This invention relates to the field of primer technology, specifically to a water-based primer resin, a water-based primer, and a method for preparing the same. Background Technology

[0002] Car bumpers are made of polypropylene composite materials such as talc, EPDM rubber, and polypropylene, possessing excellent chemical resistance, heat resistance, high mechanical strength, and impact resistance. However, this material has low surface energy, making it difficult for paints to penetrate and resulting in poor coating performance. Therefore, the surface of the car bumper needs to be treated before painting, using methods such as flame treatment, plasma treatment, corona treatment, or benzophenone / UV light treatment. Among these, flame treatment is the most common method for bumper surface treatment, utilizing the vaporization flame to oxidize the surface of the polypropylene composite material, thereby increasing the surface polarity. However, bumpers are irregularly shaped parts, and flame treatment often misses areas, leading to quality defects. Furthermore, flame treatment alone is insufficient for painting bumpers; a chlorinated polypropylene primer is still required after flame treatment. This primer is typically made using low-chlorination chlorinated polypropylene resin as the base resin, dissolved in an organic solvent, and with the addition of various fillers and additives.

[0003] As a vital national industry, the automotive sector has a significant demand for surface coatings. Currently, the primers used for automotive bumper surface coatings in China are mainly oil-based chlorinated polypropylene, with a solid content of only 8-10%. The spraying and manufacturing processes generate large amounts of volatile organic solvents, severely polluting the environment and impacting human health. Therefore, there is an urgent need to develop water-based bumper primers to replace solvent-based primers and solve this environmental pollution problem.

[0004] With the increasing demands for environmentally friendly construction in the equipment manufacturing industry, environmentally friendly water-based coatings have become a development trend. Developing a high-quality water-based primer for car bumpers has become a trend in this field, especially for bumper primers that do not require flame treatment in order to improve the quality of bumper coating. Summary of the Invention

[0005] To address the environmental pollution and quality defects caused by the need for flame treatment in existing solvent-based primer resins, this invention proposes a water-based primer resin, a water-based primer paint, and a method for preparing the same.

[0006] The technical solution of the present invention is as follows:

[0007] This invention first provides an aqueous primer resin, with the following structural formula:

[0008]

[0009] In the formula, R1 is selected from R2 is selected from

[0010] The present invention also provides a method for preparing the water-based primer resin as described above, comprising the following steps:

[0011] Step 1: Add chlorinated polypropylene to an organic solvent and heat until the chlorinated polypropylene is completely dissolved to obtain chlorinated polypropylene solution A;

[0012] Step 2: Add the soft monomer, hard monomer, and (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide to an organic solvent and stir at room temperature to obtain grafting solution B;

[0013] Step 3: Dissolve benzoyl peroxide in an organic solvent until completely dissolved to obtain initiator solution C;

[0014] Step 4: Under nitrogen protection, chlorinated polypropylene solution A and grafting solution B are mixed and heated to 60-80℃. Then, initiator solution C is added dropwise. After the reaction is complete, the solvent is removed under reduced pressure to obtain the grafted chlorinated polypropylene intermediate.

[0015] Step 5: Add acetone, diisocyanate, carbon dioxide-based polyol, and dimethylolpropionic acid to the grafted chlorinated polypropylene intermediate, react at 70-85℃ for 2-3 hours, then add butanediol and continue the reaction for 1-2 hours. Cool down to 40℃, add deionized water and triethylamine, and after the reaction is complete, remove the solvent acetone to obtain the water-based primer resin.

[0016] Preferably, the mass ratio of chlorinated polypropylene to organic solvent in step 1 is 460-740:460-850;

[0017] The mass ratio of the soft monomer, hard monomer, (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide and organic solvent in step 2 is 4.8-15.3:11.6-22.6:18.5-31.8:150-400:150-400;

[0018] In step 3, the mass ratio of benzoyl peroxide to organic solvent is 1.4-2.9:15-35;

[0019] The low-valence rate mentioned in step 4 is 0.8-2.0 mL / min;

[0020] The mass ratio of acetone, diisocyanate, carbon dioxide-based polyol, dimethylolpropionic acid, butanediol, deionized water, and triethylamine in step 5 is 380-850: 24.5-34.6: 672-1052: 4.8-6.8: 2.4-4.1: 1600-2200: 3.9-6.1.

[0021] Preferably, the chlorinated polypropylene is a chlorinated polypropylene with a weight-average molecular weight (Mw) of 80,000 to 300,000 and a chlorine content of 10% to 40%.

[0022] Preferably, the organic solvent is one or a combination of at least two of toluene, xylene, dichloromethane, carbon tetrachloride, and trichloroethane.

[0023] Preferably, the soft monomer is one of lauryl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecanyl methacrylate, and octadecyl methacrylate.

[0024] The hard monomer is one of styrene, acrylonitrile, methyl methacrylate, hydroxyethyl acrylate, glycidyl methacrylate, and butyl methacrylate.

[0025] Preferably, the initiator is one or more of benzoyl peroxide, dicumyl peroxide, dilauryl peroxide, 1,1-di(tert-butylperoxy)3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl peracetate, tert-amyl peroxide, and dilauryl peroxide.

[0026] The diisocyanate is preferably one or more of toluene diisocyanate, diphenylmethane diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, lysine diisocyanate, and phenylmethylene diisocyanate.

[0027] The carbon dioxide-based polyol was synthesized according to the method of invention patent 201210086834.X, with a molecular weight of 2000-5000 g / mol and a carbonate content of 41-60.8%.

[0028] Preferably, the (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide is prepared by the following steps:

[0029] Add 98.1g of maleic anhydride to a three-necked flask, add 200mL of xylene and 0.1g of p-hydroxyanisole, purge with nitrogen for protection, control the temperature at 55℃, and stir for 15min to form a solution.

[0030] 210.6 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was added dropwise to the reaction system over 30 min. After the addition was complete, the reaction continued for 1.5 h. Then, 0.15 g of p-toluenesulfonic acid was added, and the temperature was controlled at 135 °C. Water was separated using a water separator, and the reaction continued for 3.5 h.

[0031] Cool to 55℃, add 220ml of 20% sodium carbonate solution, and neutralize for 25 minutes;

[0032] The upper organic phase was separated and washed three times with 160 ml of 20% sodium carbonate solution. The solvent was removed under reduced pressure to obtain (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide.

[0033] The present invention also provides a water-based primer, which is prepared using the above-mentioned water-based primer resin as a raw material.

[0034] A method for preparing the above-mentioned water-based primer includes the following steps:

[0035] Step 1: Add 35-60g of water-based primer resin, 15-25g of titanium dioxide, 2-8g of barium sulfate, 0.5-1.1g of carbon black, 0.3-0.8g of water-based wetting and dispersing agent, and 0.4-0.7g of water-based defoamer to a high-speed disperser. Stir at 1000-1200 rpm at room temperature for 40-60 minutes. After complete dispersion, transfer the mixture to a sand mill for sand milling. When the fineness reaches 10μm, transfer it back to the high-speed disperser.

[0036] Step 2: When the material enters the high-speed disperser, add 0.2-0.7g of water-based wetting and leveling agent and 15-20g of film-forming aid. Stir at 600-800rpm for 20-30 minutes at room temperature to obtain the water-based primer for the bumper.

[0037] Preferably, the aqueous wetting and dispersing agent is at least one selected from BYK-180, BYK-190, BYK-191, BYK-192, BYK-194, BYK-199, BYK-2015, NUOSPERSE FX 365, and NUOSPERSE FX 600;

[0038] The aqueous defoamer is at least one of BYK-022, BYK-024, BYK-028, BYK-093, BYK-1786, DAPRODF7010, DAPRO DF 7015, DAPRO DF 7160, DAPRO DF 307, DAPRO DF 7580, TEGO FOAMEX822, TEGO AIREX 901W, and TEGO AIREX 902W.

[0039] Preferably, the film-forming aid is at least one selected from dodecyl alcohol ester, diethylene glycol butyl ether, dipropylene glycol monobutyl ether, dipropylene glycol methyl ether, dipropylene glycol monopropyl ether, and tripropylene glycol monobutyl ether.

[0040] The water-based wetting and leveling agent is at least one of BYK-346, BYK-381, BYK-3456, BYK-3760, DAPRO U-99, and DAPRO W-77.

[0041] Compared with the prior art, the specific beneficial effects of the present invention are as follows:

[0042] The water-based primer resin for bumpers provided by this invention is a green and environmentally friendly water-based resin, which solves the major environmental pollution caused by traditional solvent-based primer resins. This water-based primer resin can achieve excellent adhesion to bumpers without flame treatment, and can meet automotive-grade standards.

[0043] The carbonate and ether bonds in the carbon dioxide-based polyol structure can improve the hydrolysis resistance of the water-based primer, as well as its water and damp heat resistance. The introduction of siloxane groups through maleic anhydride enhances the adhesion between the water-based primer and the bumper substrate, achieving an adhesion rating of 0. The combined action of hard and soft monomers not only improves the hardness (HB-H) of the water-based primer but also further enhances its water resistance; 800 hours of water resistance testing shows a water absorption rate of less than 10%. The chlorinated polypropylene structure enables excellent adhesion between the primer and the bumper. Attached Figure Description

[0044] Figure 1 This is a SEM image of the cross-section of the dried film obtained in Example 1;

[0045] Figure 2 SEM image of the cross-section of the dried film obtained in Comparative Example 1.

[0046] Figure 3 The images show a comparison of the morphology of the dried films obtained in Example 1 and Comparative Example 3 after immersion in water for 800 hours. Detailed Implementation

[0047] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0048] To address the environmental pollution and quality defects caused by flame treatment required by existing solvent-based primer resins, this invention provides a water-based primer resin and its preparation method, with the specific preparation scheme as follows:

[0049] First, intermediate 1 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide was prepared:

[0050] 98.1 g of maleic anhydride was added to a three-necked flask, along with 200 ml of xylene and 0.1 g of p-hydroxyanisole. Under nitrogen protection, the mixture was stirred at 55 °C for 15 min to form a solution. Then, 210.6 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was slowly added dropwise to the reaction system over 30 min. After the addition was complete, the reaction was continued for 1.5 h. Then, 0.15 g of p-toluenesulfonic acid was added, and the temperature was maintained at 135 °C. Water was separated using a water separator, and the reaction was stopped after 3.5 h. The temperature was lowered to 55 °C, and 220 ml of a 20% sodium carbonate solution was added for neutralization for 25 min. The upper organic phase was separated and washed three times with 160 ml of a 20% sodium carbonate solution. The solvent was removed under reduced pressure to obtain intermediate 1 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide.

[0051] Further preparation of water-based primer resin:

[0052] Step 1: Add 460-740g of chlorinated polypropylene to 460-850g of toluene, and heat to 55-90℃ to completely dissolve the chlorinated polypropylene, forming chlorinated polypropylene solution A;

[0053] Step 2: Add 4.8-15.3g lauryl methacrylate, 11.6-22.6g styrene, and 18.5-31.8g intermediate 1 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide to 150-400g toluene and stir at room temperature for 30min to obtain grafting solution B;

[0054] Step 3: Dissolve 1.4-2.9g of benzoyl peroxide in 15-35g of toluene until completely dissolved to obtain initiator solution C;

[0055] Step 4: Under nitrogen protection, add chlorinated polypropylene solution A and grafting solution B into a three-necked flask, raise the reaction temperature to 60-80℃, add initiator solution C dropwise into the reaction flask at a rate of 0.8-2.0 ml / min, and continue the reaction for 2-4 hours after all the solution has been added. Remove the solvent under reduced pressure to obtain grafted chlorinated polypropylene intermediate 2.

[0056] Step 5: Add 380-850g acetone, 24.5-34.6g toluene diisocyanate, 672-1052g carbon dioxide-based polyol, and 4.8-6.8g dimethylolpropionic acid to intermediate 2. Control the temperature at 70-85℃ and react for 2-3 hours. Then add 2.4-4.1g butanediol and continue reacting for 1-2 hours. Reduce the temperature to 40℃, add 1600-2200g deionized water and 3.9-6.1g triethylamine, and react for 40 minutes. Remove the solvent acetone to obtain the water-based bumper water-based primer resin.

[0057] Based on the above scheme, the technical solution and technical effects of the present invention will be specifically described below with reference to some implementation cases and comparative cases.

[0058] Example 1.

[0059] Preparation of water-based primer resin:

[0060] Step 1: Add 510g of chlorinated polypropylene (Mw=80,000, chlorine content 10%) to 620g of toluene, heat to 80℃ to completely dissolve the chlorinated polypropylene, forming chlorinated polypropylene solution A;

[0061] Step 2: Add 6.8g lauryl methacrylate, 11.6g styrene, and 21.5g intermediate 1 to 220g toluene and stir at room temperature for 30min to obtain grafting solution B;

[0062] Step 3: Dissolve 1.8g of benzoyl peroxide in 20g of toluene until completely dissolved to obtain initiator solution C;

[0063] Step 4: Under nitrogen protection, chlorinated polypropylene solution A and grafting solution B were added to a three-necked flask. The reaction temperature was raised to 80°C. Initiator solution C was added dropwise to the reaction flask at a rate of 0.8 ml / min. After all the solution was added, the reaction was continued for 2 hours. The solvent was removed under reduced pressure to obtain grafted chlorinated polypropylene intermediate 2.

[0064] Step 5: Add 380g acetone, 28.5g toluene diisocyanate, 695g carbon dioxide-based polyol (Invention Patent 201210086834.X, Example 9, Mn = 2000g / mol, carbonate content is 43.8%), and 5.7g dimethylolpropionic acid to intermediate 2. Control the temperature at 85℃ and react for 2h. Then add 2.6g butanediol and continue reacting for 1h. Reduce the temperature to 30℃, add 1600g deionized water and 4.2g triethylamine, react for 40min, remove the solvent acetone, and obtain the water-based primer resin.

[0065] Example 2.

[0066] Preparation of water-based primer resin:

[0067] Step 1: Add 600g of chlorinated polypropylene (Mw=300,000, chlorine content 40%) to 810g of xylene, heat to 80℃ to completely dissolve the chlorinated polypropylene, forming chlorinated polypropylene solution A;

[0068] Step 2: Add 15.3g of tridecyl methacrylate, 22.6g of acrylonitrile, and 30.5g of intermediate 1 to 300g of xylene, and stir at room temperature for 30min to obtain grafting solution B;

[0069] Step 3: Dissolve 2.6g of dicumyl peroxide in 25g of xylene until completely dissolved to obtain initiator solution C;

[0070] Step 4: Under nitrogen protection, chlorinated polypropylene solution A and grafting solution B were added to a three-necked flask. The reaction temperature was raised to 70°C. Initiator solution C was added dropwise to the reaction flask at a rate of 1.5 ml / min. After all the solution was added, the reaction was continued for 3.5 h. The solvent was removed under reduced pressure to obtain grafted chlorinated polypropylene intermediate 2.

[0071] Step 5: Add 820g acetone, 34.6g diphenylmethane diisocyanate, 1052g carbon dioxide-based polyol (Invention Patent 201210086834.X, Example 4, Mn = 5000g / mol, carbonate content is 60.8%), and 6.8g dimethylolpropionic acid to intermediate 2. Control the temperature at 75℃ and react for 3h. Then add 3.4g butanediol and continue reacting for 2h. Reduce the temperature to 30℃, add 2200g deionized water and 6.1g triethylamine, react for 40min, remove the solvent acetone, and obtain the water-based primer resin.

[0072] Example 3.

[0073] Preparation of water-based primer resin:

[0074] Step 1: Add 460g of chlorinated polypropylene (Mw=120,000, chlorine content 15%) to 510g of dichloromethane, heat to 60℃ to completely dissolve the chlorinated polypropylene, forming chlorinated polypropylene solution A;

[0075] Step 2: Add 7.2g tetradecyl methacrylate, 11.8g glycidyl methacrylate, and 18.5g intermediate 1 to 150g dichloromethane and stir at room temperature for 30min to obtain grafting solution B;

[0076] Step 3: Dissolve 1.4g of 1,1-bis(tert-butylperoxy)3,3,5-trimethylcyclohexane in 15g of dichloromethane until completely dissolved to obtain initiator solution C;

[0077] Step 4: Under nitrogen protection, chlorinated polypropylene solution A and grafting solution B were added to a three-necked flask. The reaction temperature was raised to 75°C. Initiator solution C was added dropwise to the reaction flask at a rate of 1 ml / min. After all the solution was added, the reaction was continued for 2.5 h. The solvent was removed under reduced pressure to obtain grafted chlorinated polypropylene intermediate 2.

[0078] Step 5: Add 600g acetone, 28.1g isophorone diisocyanate, 920g carbon dioxide-based polyol (Invention Patent 201210086834.X, Example 13, Mn = 3000g / mol, carbonate content is 50%), and 6.3g dimethylolpropionic acid to intermediate 2. Control the temperature at 75℃ and react for 2.5h. Then add 2.7g butanediol and continue reacting for 2h. Reduce the temperature to 30℃, add 1800g deionized water and 5.0g triethylamine, react for 40min, remove the solvent acetone, and obtain the water-based primer resin.

[0079] Example 4.

[0080] Preparation of water-based primer resin:

[0081] Step 1: Add 485g of chlorinated polypropylene (Mw=150,000, chlorine content 20%) to 460g of carbon tetrachloride, heat to 65℃ to completely dissolve the chlorinated polypropylene, forming chlorinated polypropylene solution A;

[0082] Step 2: Add 4.8g hexadecyl methacrylate, 12.4g butyl methacrylate, and 21.6g intermediate 1 to 260g carbon tetrachloride and stir at room temperature for 30min to obtain graft solution B;

[0083] Step 3: Dissolve 2.3g of 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane in 30g of carbon tetrachloride until completely dissolved to obtain initiator solution C;

[0084] Step 4: Under nitrogen protection, chlorinated polypropylene solution A and grafting solution B were added to a three-necked flask. The reaction temperature was raised to 70°C. Initiator solution C was added dropwise to the reaction flask at a rate of 0.8 ml / min. After all the solution was added, the reaction was continued for 2 hours. The solvent was removed under reduced pressure to obtain grafted chlorinated polypropylene intermediate 2.

[0085] Step 5: Add 700g acetone, 26.1g dicyclohexylmethane diisocyanate, 672g carbon dioxide-based polyol (Invention Patent 201210086834.X, Example 8, Mn = 2300g / mol, carbonate content 41%), and 4.8g dimethylolpropionic acid to intermediate 2. Control the temperature at 75℃ and react for 2 hours. Then add 2.4g butanediol and continue reacting for 2 hours. Reduce the temperature to 30℃, add 2000g deionized water and 3.9g triethylamine, react for 40 minutes, remove the solvent acetone, and obtain the water-based primer resin.

[0086] Example 5.

[0087] Preparation of water-based primer resin:

[0088] Step 1: Add 710g of chlorinated polypropylene (Mw=200,000, chlorine content 25%) to 850g of xylene, heat to 90℃ to completely dissolve the chlorinated polypropylene, forming chlorinated polypropylene solution A;

[0089] Step 2: Add 6.9g of hexadecyl methacrylate, 16.5g of styrene, and 24.7g of intermediate 1 to 350g of xylene and stir at room temperature for 30min to obtain grafting solution B;

[0090] Step 3: Dissolve 2.9g of tert-amyl peroxide in 35g of xylene until completely dissolved to obtain initiator solution C;

[0091] Step 4: Under nitrogen protection, chlorinated polypropylene solution A and grafting solution B were added to a three-necked flask. The reaction temperature was raised to 65°C. Initiator solution C was added dropwise to the reaction flask at a rate of 2.0 ml / min. After all the solution was added, the reaction was continued for 3.5 h. The solvent was removed under reduced pressure to obtain grafted chlorinated polypropylene intermediate 2.

[0092] Step 5: Add 850g acetone, 28.3g 1,6-hexamethylene diisocyanate, 750g carbon dioxide-based polyol (Invention Patent 201210086834.X, Example 6, Mn = 4400g / mol, carbonate content 56.2%), and 5.7g dimethylolpropionic acid to intermediate 2. Control the temperature at 70℃ and react for 3h. Then add 3.7g butanediol and continue reacting for 2h. Reduce the temperature to 35℃, add 1850g deionized water and 4.6g triethylamine, react for 40min, remove the solvent acetone, and obtain the water-based primer resin.

[0093] Example 6.

[0094] Preparation of water-based primer resin:

[0095] Step 1: Add 740g of chlorinated polypropylene (Mw=300,000, chlorine content 22%) to 785g of trichloroethane, heat to 55℃ to completely dissolve the chlorinated polypropylene, forming chlorinated polypropylene solution A;

[0096] Step 2: Add 6.5g of octadecyl methacrylate, 14.2g of glycidyl methacrylate, and 31.8g of intermediate 1 to 400g of trichloroethane and stir at room temperature for 30min to obtain graft solution B;

[0097] Step 3: Dissolve 2.1g of dilauryl peroxide in 26g of trichloroethane until completely dissolved to obtain initiator solution C;

[0098] Step 4: Under nitrogen protection, chlorinated polypropylene solution A and grafting solution B were added to a three-necked flask. The reaction temperature was raised to 60°C. Initiator solution C was added dropwise to the reaction flask at a rate of 2.0 ml / min. After all the solution was added, the reaction was continued for 4 hours. The solvent was removed under reduced pressure to obtain grafted chlorinated polypropylene intermediate 2.

[0099] Step 5: Add 720g acetone, 24.5g isophorone diisocyanate, 820g carbon dioxide-based polyol (Invention Patent 201210086834.X, Example 13, Mn = 3000g / mol, carbonate content is 50%), and 6.8g dimethylolpropionic acid to intermediate 2. Control the temperature at 75℃ and react for 2h. Then add 4.1g butanediol and continue to react for 2h. Reduce the temperature to 40℃, add 2180g deionized water and 6.1g triethylamine, react for 40min, remove the solvent acetone, and obtain the water-based primer resin.

[0100] Comparative Example 1.

[0101] Preparation of water-based primer resin:

[0102] Prepared according to the method of Example 1, except that intermediate 1 is replaced by maleic anhydride. After completing step 4, the reaction is terminated to obtain grafted chlorinated polypropylene primer resin.

[0103] Comparative Example 2.

[0104] Preparation of water-based primer resin:

[0105] Prepared according to the method of Example 1, except that after completing step 4, the reaction is terminated to obtain grafted chlorinated polypropylene primer resin.

[0106] Comparative Example 3.

[0107] Preparation of water-based primer resin:

[0108] Prepared according to the method of Example 1, except that the carbon dioxide-based polyol was replaced by polybutylene adipate diol (Mn=2000). After completing step 4, the reaction was terminated. Everything else was the same, and the resulting product was a grafted chlorinated polypropylene primer resin.

[0109] Example 7.

[0110] Preparation of water-based primer for bumpers:

[0111] Prepare the water-based primer for the bumper using the following steps, following the raw material configuration in Table 1.

[0112] Step 1: Add water-based primer resin, titanium dioxide, barium sulfate, carbon black, water-based wetting and dispersing agent, and water-based defoamer to a high-speed disperser. Stir at 1000-1200 rpm for 40-60 minutes at room temperature. After complete dispersion, transfer the mixture to a sand mill for sand milling. When the fineness reaches 10μm, transfer it back to the high-speed disperser.

[0113] Step 2: When the material enters the high-speed disperser, add water-based wetting and leveling agent and film-forming aid. Stir at 600-800 rpm for 20-30 minutes at room temperature to obtain water-based primer for the bumper.

[0114] Table 1

[0115]

[0116]

[0117] Example of results.

[0118] I. Performance testing of water-based primer resin:

[0119] 1. Particle size test:

[0120] The water-based primer resins DT01-DT06 and DB01-DB02 were diluted in Malvern cuvettes (DTS0012) and then tested using a Brookhaven ZetaPlus analyzer dynamic light scattering (DLS) instrument at a temperature of 25°C.

[0121] 2. Zeta potential test:

[0122] After diluting the aqueous primer resins DT01-DT06 and DB01-DB02, they were transferred into a folded capillary cell (DTS1070) and tested on a Nano-ZS90 of Malvern ZETASIZER Nano series dynamic light scattering (DLS) instrument.

[0123] 3. Emulsion stability test:

[0124] Water-based primer resins DT01-DT06 and DB01-DB02 were centrifuged at 5000 rpm for 30 minutes, and the bottom was observed to see if any precipitate was formed.

[0125] 4. Water absorption rate test:

[0126] Waterborne primer resins DT01-DT06 and DB01-DB02 were placed in a polytetrafluoroethylene tray at room temperature and air-dried at room temperature for 24 hours. Then, they were placed in a vacuum oven and dried at 40°C for 72 hours to obtain a film.

[0127] The film was cut into dumbbell-shaped pieces and immersed in deionized water at 25°C for 800 hours. The mass of the film before and after immersion was measured and calculated using the following equation:

[0128] WB = (m1 - m0) / m0 × 100%,

[0129] Where WB(%) is the water absorption rate of the film, m0(g) is the initial mass of the film before immersion, and m1(g) is the mass of the film after immersion for a period of time.

[0130] 5. Scanning electron microscopy (SEM) test of thin film cross section: Prepare a dry thin film according to the method in step 4 (water absorption test) above, then freeze it in liquid nitrogen for 20 min, break the film into brittle fragments, and perform SEM test by sputtering gold on the surface.

[0131] 6. Adhesion (cross-cut test): The test shall be conducted in accordance with the method of GB / T 13217.7-2009.

[0132] 7. Surface tension test: The surface tension of the paint film was tested using deionized water as the medium on a QBZY-3 fully automatic interfacial tension meter.

[0133] 8. Hardness (pencil hardness) test: The test shall be conducted in accordance with the method of GB / T6739-2022.

[0134] II. Preparation of water-based primer film for bumpers:

[0135] Wipe the dust off the surface of the composite polypropylene material of the bumper with a lint-free cloth. Then, under conditions of 65% humidity and 25°C, apply a water-based primer to the surface using an air spraying method. Activate the coating in a 60°C oven for 5 minutes. The dry film thickness is 3-4 micrometers. After seven days, perform relevant performance tests on the paint film.

[0136] Table 2 Performance of Waterborne Primer Resins

[0137]

[0138] The results of emulsion appearance, average particle size, and Zeta potential indicate that the aqueous emulsion obtained in the embodiments of the present invention has excellent stability and small latex particles. Hardness results show that the technical solution of the present invention can improve hardness, reaching HB-H, while the comparative example is only 2B. The paint film obtained by the present invention, after a water immersion test of up to 800 hours, showed a water absorption rate of less than 10%, while the comparative example was over 15%, and the comparative example 3 had an even higher water absorption rate of 46.8%. This is because the structure lacks a carbon dioxide-based polyol structure, resulting in decreased water resistance. (See attached...) Figure 3 (The left side shows the results of Example 1, and the right side shows the results of Comparative Example 3.) It can be seen that after 800 hours of water immersion, the paint film obtained in Example 1 did not show significant swelling, while the paint film in Comparative Example 3 showed significant swelling and a marked increase in length, further demonstrating the good water resistance of the paint film obtained by this invention. (See attached...) Figure 1 and attached Figure 2 The results show that the cross-section of the product in Example 1 exhibits obvious ductile fracture, which proves that the material has good toughness and thus good adhesion to the substrate. In contrast, the comparative example shows brittle fracture, and the adhesion to the substrate decreases.

[0139] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A water-based primer resin, characterized in that, The structural formula is as follows: ， In the formula, R1 is selected from R2 is selected from ; R3 is selected from , , , , , , , ; In the formula, m, n, and p are all non-zero.

2. A method for preparing the water-based primer resin as described in claim 1, characterized in that, Includes the following steps: Step 1: Add chlorinated polypropylene to an organic solvent and heat until the chlorinated polypropylene is completely dissolved to obtain chlorinated polypropylene solution A; Step 2: Add the soft monomer, hard monomer, and (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide to an organic solvent and stir at room temperature to obtain grafting solution B; Step 3: Dissolve benzoyl peroxide in an organic solvent until completely dissolved to obtain initiator solution C; Step 4: Under nitrogen protection, chlorinated polypropylene solution A and grafting solution B are mixed and heated to 60-80℃. Then, initiator solution C is added dropwise. After the reaction is complete, the solvent is removed under reduced pressure to obtain the grafted chlorinated polypropylene intermediate. Step 5: Add acetone, diisocyanate, carbon dioxide-based polyol, and dimethylolpropionic acid to the grafted chlorinated polypropylene intermediate, react at 70-85℃ for 2-3 hours, then add butanediol and continue the reaction for 1-2 hours. Cool down to 40℃, add deionized water and triethylamine, and after the reaction is complete, remove the solvent acetone to obtain the water-based primer resin.

3. The method for preparing the water-based primer resin according to claim 2, characterized in that, The organic solvent is one or a combination of at least two of toluene, xylene, dichloromethane, carbon tetrachloride, and trichloroethane.

4. The method for preparing the water-based primer resin according to claim 2, characterized in that, The soft monomer is one of lauryl methacrylate and octadecyl methacrylate; The hard monomer is one of styrene, acrylonitrile, methyl methacrylate, and glycidyl methacrylate.

5. The method for preparing the water-based primer resin according to claim 2, characterized in that, The initiator is one or more of the following: benzoyl peroxide, dicumyl peroxide, dilauroyl peroxide, 1,1-di(tert-butylperoxy)3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl peracetate, tert-amyl peroxide, and dilauroyl peroxide. The diisocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, lysine diisocyanate, and phenylmethylene diisocyanate.

6. The method for preparing the water-based primer resin according to claim 2, characterized in that, The (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide was prepared by the following steps: Add 98.1g of maleic anhydride to a three-necked flask, add 200mL of xylene and 0.1g of p-hydroxyanisole, purge with nitrogen for protection, control the temperature at 55℃, and stir for 15min to form a solution. 210.6 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was added dropwise to the reaction system over 30 min. After the addition was complete, the reaction continued for 1.5 h. Then, 0.15 g of p-toluenesulfonic acid was added, and the temperature was controlled at 135 °C. Water was separated using a water separator, and the reaction continued for 3.5 h. Cool to 55℃, add 220ml of 20% sodium carbonate solution, and neutralize for 25 minutes; The upper organic phase was separated and washed three times with 160 ml of 20% sodium carbonate solution. The solvent was removed under reduced pressure to obtain (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide.

7. A water-based primer, characterized in that, It is prepared using the water-based primer resin described in claim 1 as a raw material.

8. A method for preparing a water-based primer as described in claim 7, characterized in that, It includes the following steps: Step 1: Add 35-60g of water-based primer resin, 15-25g of titanium dioxide, 2-8g of barium sulfate, 0.5-1.1g of carbon black, 0.3-0.8g of water-based wetting and dispersing agent, and 0.4-0.7g of water-based defoamer to a high-speed disperser. Stir at 1000-1200 rpm at room temperature for 40-60 minutes. After complete dispersion, transfer the mixture to a sand mill for sand milling. When the fineness reaches 10μm, transfer it back to the high-speed disperser. Step 2: When the material enters the high-speed disperser, add 0.2-0.7g of water-based wetting and leveling agent and 15-20g of film-forming aid. Stir at 600-800rpm for 20-30 minutes at room temperature to obtain the water-based primer for the bumper.

9. The method for preparing the water-based primer according to claim 8, characterized in that, The aqueous wetting and dispersing agent is at least one of BYK-180, BYK-190, BYK-191, BYK-192, BYK-194, BYK-199, BYK-2015, NUOSPERSEFX365, and NUOSPERSEFX600; The aqueous defoamer is at least one of BYK-022, BYK-024, BYK-028, BYK-093, BYK-1786, DAPRODF7010, DAPRODF7015, DAPRODF7160, DAPRODF307, DAPRODF7580, TEGOFOAMEX822, TEGOAIREX901W, and TEGOAIREX902W.

10. The method for preparing the water-based primer according to claim 8, characterized in that, The film-forming aid is at least one of dodecyl alcohol ester, diethylene glycol butyl ether, dipropylene glycol monobutyl ether, dipropylene glycol methyl ether, dipropylene glycol monopropyl ether, and tripropylene glycol monobutyl ether. The water-based wetting and leveling agent is at least one of BYK-346, BYK-381, BYK-3456, BYK-3760, DAPROU-99, and DAPROW-77.

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