Water-based prime coat resin, water-based prime coat paint and preparation method of water-based prime coat resin

Abstract

The invention discloses water-based prime coat resin, water-based prime coat paint and a preparation method of the water-based prime coat resin, relates to the technical field of prime coat paint, and solves the problems of environmental pollution and quality defect caused by flame treatment in the existing prime coat. Chlorinated polypropylene is added into an organic solvent and heated to be completely dissolved, and chlorinated polypropylene liquid A is obtained; the preparation method comprises the following steps: adding a soft monomer, a hard monomer and (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl) maleimide into an organic solvent, and stirring to obtain a grafting solution B; dissolving benzoyl peroxide in an organic solvent to obtain an initiator solution C; under the protection of nitrogen, mixing A and B, heating to 60-80 DEG C, dropwise adding C, and decompressing to remove the solvent after the reaction is finished, so as to obtain an intermediate; adding acetone, diisocyanate, carbon dioxide-based polyol and dimethylolpropionic acid into the intermediate for reaction, then adding butanediol for continuous reaction, adding deionized water and triethylamine after cooling, and removing the solvent after reaction to obtain the water-based prime coat resin.

Description

Technical Field

[0001] The invention relates to the technical field of primer coatings, and in particular to a water-based primer coating resin, a water-based primer coating and a preparation method thereof. Background Art

[0002] The automobile bumper is a polypropylene composite material made of talcum powder, EPDM rubber and polypropylene, which has excellent chemical resistance, heat resistance, high-strength mechanical properties and impact resistance. However, the surface energy of the material is low, the coating is not easy to infiltrate it and the coating performance is poor. The surface of the automobile bumper needs to be treated before painting, and the methods include flame method, plasma, corona method or benzophenone / ultraviolet light method. Among them, the flame method is the most commonly used method for bumper surface treatment. The gasification flame part of the flame is used to oxidize the surface of the bumper polypropylene composite material, thereby increasing the polarity of the bumper surface. However, the bumper is a special-shaped part, and the flame method often has parts that cannot be treated on the bumper, which will cause quality defects. And flame treatment alone still cannot meet the requirements of bumper coating paint. It is still necessary to apply a layer of chlorinated polypropylene primer paint on the surface after flame treatment. It is usually prepared by using a chlorinated polypropylene resin with a low degree of chlorination as the base resin, dissolving it in an organic solvent, and adding various fillers and additives.

[0003] As an important industry in China, the automobile industry has a large demand for surface coatings. At present, the primer of domestic automobile bumper surface coatings is mainly oily chlorinated polypropylene, whose solid content is only 8-10%. A large amount of organic solvents are volatilized during the spraying and manufacturing process, which seriously pollutes the environment and affects human health. Therefore, it is urgent to develop a water-based bumper primer to replace the solvent-based bumper primer to solve this environmental pollution problem.

[0004] With the requirements of equipment manufacturing industry for environmentally friendly construction, environmentally friendly water-based coatings have become a development trend. How to develop a high-quality water-based primer for automobile bumpers has become a development trend in this field, especially in order to improve the quality of bumper coating, a bumper primer that is free of flame treatment is required. Summary of the invention

[0005] In order to solve the problems that the existing solvent-based primer resin pollutes the environment and requires flame treatment to cause quality defects, the present invention provides a water-based primer resin, a water-based primer paint and a preparation method thereof.

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

[0007] The present invention first provides a water-based primer resin, the structural formula of which is as follows:

[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, adding chlorinated polypropylene into an organic solvent, heating to completely dissolve the chlorinated polypropylene, and obtaining chlorinated polypropylene liquid A;

[0012] Step 2, adding soft monomer, hard monomer and (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide into an organic solvent and stirring at room temperature to obtain a grafting solution B;

[0013] Step 3, dissolving benzoyl peroxide in an organic solvent until it is completely dissolved to obtain an initiator solution C;

[0014] Step 4: Under nitrogen protection, chlorinated polypropylene liquid A and grafting liquid B are mixed, the temperature is raised to 60-80° C., and then initiator solution C is added dropwise. After the reaction is completed, the solvent is removed under reduced pressure to obtain a 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°C for 2-3 hours, then add butanediol and continue to react for 1-2 hours, cool to 40°C, add deionized water and triethylamine, and remove the solvent acetone after the reaction is completed to obtain a water-based primer resin.

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

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

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

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

[0020] The mass ratio of acetone, diisocyanate, carbon dioxide-based polyol, dimethylol propionic 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 having a weight average molecular weight Mw of 80,000-300,000 and a chlorine content of 10-40%.

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

[0023] Preferably, the soft monomer is one of lauryl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecyl 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, diisopropylbenzene 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 peroxy-2-ethylhexanoate, and dilauroyl peroxide.

[0026] The diisocyanate is preferably one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, lysine diisocyanate, and xylylene diisocyanate.

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

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

[0029] Add 98.1 g of maleic anhydride into a three-necked flask, add 200 mL of xylene and 0.1 g of p-hydroxyanisole, introduce nitrogen protection, control the temperature at 55°C, and stir for 15 minutes to form a solution;

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

[0031] Cool down to 55°C, add 220 ml 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, and the solvent was removed under reduced pressure to obtain (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide.

[0033] The invention also provides a water-based primer, which is prepared by taking the water-based primer resin as a raw material.

[0034] A method for preparing the above-mentioned water-based primer comprises 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 dispersant, and 0.4-0.7g of water-based defoamer into a high-speed disperser, with a stirring rate of 1000-1200rpm, and stir at room temperature for 40-60min. After stirring and dispersing completely, enter the sand mill for sand grinding. When the fineness reaches 10μm, enter the high-speed disperser again;

[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 a rate of 600-800rpm, stir and mix at room temperature for 20-30min to obtain a water-based base paint for the bumper.

[0037] Preferably, 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, 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 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;

[0040] The aqueous 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:

[0042] The bumper water-based primer resin provided by the present invention is a green and environmentally friendly water-based resin, which solves the serious pollution to the environment caused by traditional solvent-based primer resins; the water-based primer resin can achieve excellent adhesion without the need for flame treatment of the bumper, and can meet automotive-grade standards.

[0043] The carbonate and ether bond structures in the carbon dioxide-based polyol structure can improve the hydrolysis resistance of the water-based primer, and improve the water resistance and moisture-heat resistance of the primer resin; the introduction of siloxane groups through maleic anhydride improves the adhesion between the water-based primer resin and the bumper substrate, and the adhesion is level 0; under the joint action of hard monomers and soft monomers, not only the hardness (HB-H) of the water-based primer resin is improved, but also the water resistance of the water-based primer resin is further improved. The 800-hour water resistance result shows that the water absorption rate is less than 10%; the chlorinated polypropylene structure can achieve excellent adhesion between the bumper. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0045] Figure 2 is a SEM image of the cross section of the dried film obtained in Comparative Example 1;

[0046] Figure 3 This is a comparison of the morphologies of the dried films obtained in Example 1 and Comparative Example 3 after being immersed in water for 800 hours. DETAILED DESCRIPTION

[0047] In order to make the technical solution of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the specification of the present invention. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as a limitation to the present invention.

[0048] In order to solve the problems that the existing solvent-based primer resin pollutes the environment and requires flame treatment to cause quality defects, the present invention provides a water-based primer resin and a preparation method thereof, and provides a specific preparation scheme as follows:

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

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

[0051] Then prepare the water-based primer resin:

[0052] Step 1: Add 460-740 g of chlorinated polypropylene into 460-850 g of toluene, and heat to 55-90° C. to completely dissolve the chlorinated polypropylene to form chlorinated polypropylene liquid A;

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

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

[0055] Step 4: Under nitrogen protection, add chlorinated polypropylene liquid A and grafting liquid B into a three-necked flask, raise the reaction temperature to 60-80°C, and dropwise add initiator solution C into the reaction flask at a dropping rate of 0.8-2.0 ml / min. After all the solution is added, continue the reaction for 2-4 hours, remove the solvent under reduced pressure, and 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 dimethylol propionic acid to intermediate 2, control the temperature at 70-85°C, react for 2-3h, then add 2.4-4.1g butanediol, continue to react for 1-2h, reduce the temperature to 40°C, add 1600-2200g deionized water and 3.9-6.1g triethylamine, react for 40min, remove the solvent acetone, and obtain a water-based bumper water-based primer resin.

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

[0058] Example 1.

[0059] Preparation of water-based primer resin:

[0060] Step 1: 510 g of chlorinated polypropylene (Mw=80,000, chlorine content 10%) was added to 620 g of toluene, and the temperature was raised to 80° C. to completely dissolve the chlorinated polypropylene to form chlorinated polypropylene liquid A;

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

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

[0063] Step 4: Under nitrogen protection, add chlorinated polypropylene liquid A and grafting liquid B into a three-necked flask, raise the reaction temperature to 80°C, and dropwise add initiator solution C into the reaction flask at a dropping rate of 0.8 ml / min. After all the solution is added, continue the reaction for 2 h, remove the solvent under reduced pressure, and 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 of 43.8%), 5.7g dimethylol propionic acid to intermediate 2, control the temperature at 85 ° C, react for 2h, then add 2.6g butanediol, continue to react for 1h, reduce the temperature to 30 ° C, add 1600g deionized water and 4.2g triethylamine, react for 40min, remove the solvent acetone, and obtain a water-based primer resin.

[0065] Example 2.

[0066] Preparation of water-based primer resin:

[0067] Step 1: 600 g of chlorinated polypropylene (Mw=300,000, chlorine content 40%) was added to 810 g of xylene, and the temperature was raised to 80° C. to completely dissolve the chlorinated polypropylene to form chlorinated polypropylene liquid A;

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

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

[0070] Step 4: Under nitrogen protection, add chlorinated polypropylene liquid A and grafting liquid B into a three-necked flask, raise the reaction temperature to 70°C, and dropwise add initiator solution C into the reaction flask at a dropping rate of 1.5 ml / min. After all the solution is added, continue the reaction for 3.5 h, remove the solvent under reduced pressure, and 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 of 60.8%), 6.8g dihydroxymethylpropionic acid to intermediate 2, control the temperature at 75 ° C, react for 3h, then add 3.4g butanediol, continue to react for 2h, reduce the temperature to 30 ° C, add 2200g deionized water and 6.1g triethylamine, react for 40min, remove the solvent acetone, and obtain a water-based primer resin.

[0072] Example 3.

[0073] Preparation of water-based primer resin:

[0074] Step 1: 460 g of chlorinated polypropylene (Mw=120,000, chlorine content 15%) was added to 510 g of dichloromethane, and the temperature was raised to 60° C. to completely dissolve the chlorinated polypropylene to form chlorinated polypropylene liquid A;

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

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

[0077] Step 4: Under nitrogen protection, add chlorinated polypropylene liquid A and grafting liquid B into a three-necked flask, raise the reaction temperature to 75°C, and dropwise add initiator solution C into the reaction flask at a dropping rate of 1 ml / min. After all the solution is added, continue the reaction for 2.5 h, remove the solvent under reduced pressure, and 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 of 50%), 6.3g dimethylol propionic acid to intermediate 2, control the temperature at 75 ° C, react for 2.5h, then add 2.7g butanediol, continue to react for 2h, reduce the temperature to 30 ° C, add 1800g deionized water and 5.0g triethylamine, react for 40min, remove the solvent acetone, and obtain a water-based primer resin.

[0079] Example 4.

[0080] Preparation of water-based primer resin:

[0081] Step 1: 485 g of chlorinated polypropylene (Mw=150,000, chlorine content 20%) was added to 460 g of carbon tetrachloride, and the temperature was raised to 65° C. to completely dissolve the chlorinated polypropylene to form chlorinated polypropylene liquid A;

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

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

[0084] Step 4: Under nitrogen protection, add chlorinated polypropylene liquid A and grafting liquid B into a three-necked flask, raise the reaction temperature to 70°C, and dropwise add initiator solution C into the reaction flask at a dropping rate of 0.8 ml / min. After all the solution is added, continue the reaction for 2 h, remove the solvent under reduced pressure, and 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 of 41%), 4.8g dimethylol propionic acid to intermediate 2, control the temperature at 75 ° C, react for 2h, then add 2.4g butanediol, continue to react for 2h, reduce the temperature to 30 ° C, add 2000g deionized water and 3.9g triethylamine, react for 40min, remove the solvent acetone, and obtain a water-based primer resin.

[0086] Example 5.

[0087] Preparation of water-based primer resin:

[0088] Step 1: 710 g of chlorinated polypropylene (Mw=200,000, chlorine content 25%) was added to 850 g of xylene, and the temperature was raised to 90° C. to completely dissolve the chlorinated polypropylene to form chlorinated polypropylene liquid A;

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

[0090] Step 3: Dissolve 2.9 g of tert-amyl peroxy 2-ethylhexanoate in 35 g of xylene until the mixture is completely dissolved to obtain an initiator solution C;

[0091] Step 4: Under nitrogen protection, add chlorinated polypropylene liquid A and grafting liquid B into a three-necked flask, raise the reaction temperature to 65°C, and dropwise add initiator solution C into the reaction flask at a dropping rate of 2.0 ml / min. After all the solution is added, continue the reaction for 3.5 h, remove the solvent under reduced pressure, and obtain grafted chlorinated polypropylene intermediate 2;

[0092] Step 5: Add 850g of acetone, 28.3g of 1,6-hexamethylene diisocyanate, 750g of carbon dioxide-based polyol (invention patent 201210086834.X, Example 6, Mn=4400g / mol, carbonate content of 56.2%), and 5.7g of dimethylol propionic acid to intermediate 2, control the temperature at 70°C, react for 3h, then add 3.7g of butanediol, continue to react for 2h, reduce the temperature to 35°C, add 1850g of deionized water and 4.6g of triethylamine, react for 40min, remove the solvent acetone, and obtain a water-based primer resin.

[0093] Example 6.

[0094] Preparation of water-based primer resin:

[0095] Step 1: 740 g of chlorinated polypropylene (Mw=300,000, chlorine content 22%) was added to 785 g of trichloroethane, and the temperature was raised to 55° C. to completely dissolve the chlorinated polypropylene to form chlorinated polypropylene liquid A;

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

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

[0098] Step 4: Under nitrogen protection, add chlorinated polypropylene liquid A and grafting liquid B into a three-necked flask, raise the reaction temperature to 60°C, and dropwise add initiator solution C into the reaction flask at a dropping rate of 2.0 ml / min. After all the solution is added, continue the reaction for 4 hours, remove the solvent under reduced pressure, and 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 of 50%), 6.8g dihydroxymethylpropionic acid to intermediate 2, control the temperature at 75 ° C, react for 2h, then add 4.1g butanediol, continue to react for 2h, reduce the temperature to 40 ° C, add 2180g deionized water and 6.1g triethylamine, react for 40min, remove the solvent acetone, and obtain a water-based primer resin.

[0100] Comparative Example 1.

[0101] Preparation of water-based primer resin:

[0102] The method of Example 1 was used to prepare the product, except that the intermediate 1 was replaced by maleic anhydride. After completing step 4, the reaction was terminated to obtain a grafted chlorinated polypropylene primer resin.

[0103] Comparative Example 2.

[0104] Preparation of water-based primer resin:

[0105] The method of Example 1 was used for preparation, except that after completing step 4, the reaction was terminated to obtain a grafted chlorinated polypropylene primer resin.

[0106] Comparative Example 3.

[0107] Preparation of water-based primer resin:

[0108] The method of Example 1 was used to prepare the grafted chlorinated polypropylene primer resin, except that the carbon dioxide-based polyol was replaced by polybutylene adipate diol (Mn=2000). After completing step 4, the reaction was terminated. The other steps were the same, and the grafted chlorinated polypropylene primer resin was obtained.

[0109] Example 7.

[0110] Preparation of water-based base paint for bumper:

[0111] According to the raw material configuration in Table 1, the following steps were used to prepare the bumper water-based primer.

[0112] Step 1: Add water-based primer resin, titanium dioxide, barium sulfate, carbon black, water-based wetting dispersant and water-based defoaming agent into a high-speed disperser at a stirring rate of 1000-1200rpm and stir at room temperature for 40-60min. After complete stirring and dispersion, enter the sand mill for sand grinding. When the fineness reaches 10μm, enter the high-speed disperser again.

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

[0114] Table 1

[0115]

[0116]

[0117] Effect example.

[0118] 1. Water-based primer resin performance test:

[0119] 1. Particle size test:

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

[0121] 2. Zeta potential test:

[0122] After diluting, the water-based primer resins DT01-DT06 and DB01-DB02 were transferred into a folded capillary cell (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] Centrifuge the water-based primer resins DT01-DT06 and DB01-DB02 at 5000 rpm for 30 minutes and observe whether there is precipitation at the bottom.

[0125] 4. Water absorption test:

[0126] The water-based primer resins DT01-DT06 and DB01-DB02 were placed in a polytetrafluoroethylene tray at room temperature, dried at room temperature for 24 hours, and then placed in a vacuum oven at 40°C and dried 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 quality of the film before and after immersion was tested and calculated using the following equation:

[0128] WB=(m1-m0) / m0×100%,

[0129] Wherein, 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. Film cross-section scanning electron microscope (SEM) test: Prepare a dry thin film according to the method in 4 (water absorption test) above, and then freeze it in liquid nitrogen for 20 minutes. After the film is broken, gold is sprayed on the surface for SEM testing.

[0131] 6. Adhesion (cross-cut method) test: Test in accordance with GB / T 13217.7-2009.

[0132] 7. Surface tension test: Deionized water is used as the medium to test the surface tension of the paint film, which is completed on the QBZY-3 fully automatic surface tension meter.

[0133] 8. Hardness (pencil hardness) test: Test in accordance with GB / T6739-2022 method.

[0134] 2. Preparation of water-based primer film for bumper:

[0135] Wipe the dust off the surface of the bumper composite polypropylene composite material with a dust-free cloth, and then spray the water-based primer on its surface by air spraying at a humidity of 65% and a temperature of 25°C. Activate it in a 60°C oven for 5 minutes. The dry film thickness is 3-4 microns. After leaving it for seven days, carry out paint film related performance tests.

[0136] Table 2 Water-based primer resin properties

[0137]

[0138] The results of the emulsion appearance, average particle size and Zeta potential show that the aqueous emulsion obtained in the embodiment of the present invention has excellent stability and the latex particles are relatively small. The results of the hardness show that the technical solution of the present invention can improve the hardness, and the hardness is as high as HB-H, while the comparative example is only 2B. The paint film obtained by the present invention has been subjected to a water immersion test for up to 800 hours, and the water absorption rate is within 10%, while the comparative example is above 15%. The water absorption rate of comparative example 3 is even higher, reaching 46.8%. This is because there is no carbon dioxide-based polyol structure in the structure, which causes a decrease in water resistance. From the attached Figure 3 (The left side is the result of Example 1, and the right side is the result of Comparative Example 3) It can be seen that after the paint film obtained in Example 1 was soaked in water for 800 hours, the film did not swell significantly, while the paint film of Comparative Example 3 swelled significantly and its length increased significantly, further indicating that the paint film obtained by the present invention has good water resistance. Figure 1 and attached Figure 2 It can be seen from the results that the cross section of the product of Example 1 shows obvious ductile fracture, which proves that the material has good toughness and thus has good adhesion to the substrate, while the comparative example shows brittle fracture and reduced adhesion to the substrate.

[0139] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution 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 2. A method for preparing a water-based primer resin as claimed in claim 1, characterized in that: The steps include: Step 1, adding chlorinated polypropylene into an organic solvent, heating to completely dissolve the chlorinated polypropylene, and obtaining chlorinated polypropylene liquid A; Step 2, adding soft monomer, hard monomer and (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide into an organic solvent and stirring at room temperature to obtain a grafting solution B; Step 3, dissolving benzoyl peroxide in an organic solvent until it is completely dissolved to obtain an initiator solution C; Step 4: Under nitrogen protection, chlorinated polypropylene liquid A and grafting liquid B are mixed, the temperature is raised to 60-80° C., and then initiator solution C is added dropwise. After the reaction is completed, the solvent is removed under reduced pressure to obtain a 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°C for 2-3 hours, then add butanediol and continue to react for 1-2 hours, cool to 40°C, add deionized water and triethylamine, and remove the solvent acetone after the reaction is completed to obtain a 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 of toluene, xylene, dichloromethane, carbon tetrachloride, and trichloroethane, or a combination of at least two of them.

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, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecyl methacrylate, and octadecyl methacrylate; The hard monomer is one of styrene, acrylonitrile, methyl methacrylate, hydroxyethyl acrylate, glycidyl methacrylate and butyl 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 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 peroxyacetate, tert-amyl peroxy-2-ethylhexanoate, and dilauroyl peroxide; The diisocyanate is preferably one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, lysine diisocyanate, and xylylene 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 is prepared by the following steps: Add 98.1 g of maleic anhydride into a three-necked flask, add 200 mL of xylene and 0.1 g of p-hydroxyanisole, introduce nitrogen protection, control the temperature at 55°C, and stir for 15 minutes to form a solution; 210.6 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was added dropwise to the reaction system within 30 min. After all the addition was completed, the reaction was continued for 1.5 h. 0.15 g of p-toluenesulfonic acid was added. The temperature was controlled at 135 ° C. Water was separated by a water separator and the reaction was continued for 3.5 h. Cool down to 55°C, add 220 ml 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, and the solvent was removed under reduced pressure to obtain (N-(2-aminoethyl)-3-aminopropyltrimethoxysilyl)maleimide.

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

8. A method for preparing a water-based primer as claimed in claim 7, characterized in that: The following steps are included: 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 dispersant, and 0.4-0.7g of water-based defoamer into a high-speed disperser, with a stirring rate of 1000-1200rpm, and stir at room temperature for 40-60min. After stirring and dispersing completely, enter the sand mill for sand grinding. When the fineness reaches 10μm, enter the high-speed disperser again; 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 a rate of 600-800rpm, stir and mix at room temperature for 20-30min to obtain a water-based base paint for the bumper.

9. The method for preparing a 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, NUOSPERSE FX 365, and NUOSPERSE FX 600; The aqueous defoamer is at least one of BYK-022, BYK-024, BYK-028, BYK-093, BYK-1786, DAPRO DF7010, DAPRO DF 7015, DAPRO DF 7160, DAPRO DF 307, DAPRO DF 7580, TEGO FOAMEX 822, TEGOAIREX 901W, and TEGO AIREX 902W.

10. The method for preparing a 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 aqueous wetting and leveling agent is at least one of BYK-346, BYK-381, BYK-3456, BYK-3760, DAPRO U-99, and DAPRO W-77.

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