A method for preparing environmentally friendly and highly weather-resistant water-based automotive topcoat

Abstract

The present invention provides a method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat, comprising the following steps: mixing an acrylate monomer, an initiator and a chain transfer agent to prepare a mixed solution, adding a solvent to a reactor to raise the temperature, adding part of the mixed solution to the reactor, performing a heat preservation reaction to prepare a core layer resin material, adding an acrylate monomer to the remaining mixed solution, mixing to prepare a shell layer solution, adding the shell layer solution to the core layer resin material, continuing the heat preservation reaction, adding an amine neutralizer to the reaction solution for neutralization after the reaction, adding deionized water to adjust the solid content of the reaction solution, and preparing a water-based hydroxy acrylic acid dispersion; mixing and grinding the water-based hydroxy acrylic acid dispersion, pigments, fillers, additives and water to prepare component A, and uniformly mixing a water-based isocyanate curing agent and a solvent to prepare component B. The water-based coating provided by the present invention has good adhesion, excellent corrosion resistance, good mechanical properties, good weather resistance, and low preparation cost.

Description

Technical field:

[0001] The invention relates to the technical field of coatings, and in particular to a method for preparing an environmentally friendly and highly weather-resistant water-based automotive surface coating. Background technology:

[0002] With the development of water-based automotive coatings, the functional requirements for water-based automotive coatings are getting higher and higher. The patent with application number CN201510987857.1 discloses an anti-fouling water-based automotive nano coating, which includes the following raw materials by weight: 30-50 parts of medium-oil linseed oil alkyd resin, 20-30 parts of diatomaceous earth, 20-40 parts of pentaerythritol, 10-20 parts of bisphenol A epoxy resin, 10-20 parts of dodecanedioic acid, 5-10 parts of urea-formaldehyde resin, 5-10 parts of nano zinc oxide, 0.1-1 parts of nano flaky silver powder, 1-10 parts of dendritic polyamide amine, 1-5 parts of methyl ethyl ketone oxime, 1-5 parts of propylene glycol methyl ether acetate, 0.1-1 parts of defoaming agent, and 20-40 parts of water. The above coating has the dual advantages of water-based coatings and nano coatings, with environmentally friendly performance, strong adhesion, plump paint film, smooth and flat surface, and has a strong anti-fouling effect under the synergistic effect of each component. The patent with application number CN201910206066.9 provides a coating, using bagasse and taro peel as raw materials to prepare a reaction slurry, and the reaction slurry is concentrated, dried and ground to obtain a grinding product, and finally the grinding product is mixed with water, resin solvent and other additives, stirred and discharged to obtain an antioxidant water-based automotive coating. The present invention extracts and separates sugars, plant fibers and other substances, and decomposes to generate carboxyl, epoxy, hydroxyl, furfural and the like, thereby improving the bonding degree between molecules in the water-based automotive coating and the bonding adsorption strength with the substrate surface. The present invention introduces aluminum ions and magnesium ions, and the metal ions are adsorbed by chelation, ionic bonds and other chemical bonding forces with the fibers and sugar molecules, so that the coating is protected by a dense metal oxide protective film on the surface, thereby improving the anti-corrosion performance of the coating. It can be seen from the above-mentioned prior art that in order to prepare a highly functional water-based coating, it is necessary to modify it. Summary of the invention:

[0003] The technical problem to be solved by the present invention is to provide a method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat in view of the deficiencies in the prior art. The method is simple to operate and has low requirements on equipment. The prepared coating not only has good adhesion, but also has good mechanical properties and good weather resistance.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat comprises the following steps:

[0006] (1) mixing an acrylate monomer, an initiator and a chain transfer agent to obtain a mixed solution, adding a solvent to a reactor and heating it, then adding part of the mixed solution to the reactor, performing a first heat preservation reaction to obtain a core layer resin material, adding an acrylate monomer to the remaining mixed solution, mixing uniformly to obtain a shell layer solution, adding the shell layer solution to the core layer resin material, and continuing a second heat preservation reaction. After the reaction is completed, the mixture is cooled to room temperature, and an amine neutralizer is slowly added to the reaction solution for neutralization, and deionized water is added to adjust the solid content of the reaction solution to obtain an aqueous hydroxy acrylic dispersion having a core-shell structure;

[0007] (2) The aqueous hydroxy acrylic dispersion, pigment, filler, additive and water prepared above are mixed and ground uniformly to prepare component A, and the aqueous isocyanate curing agent and solvent are mixed uniformly to prepare component B.

[0008] As a preferred embodiment of the above technical solution, in step (1), the acrylic ester monomer is a mixture of one or more of methyl methacrylate, n-butyl methacrylate, isooctyl acrylate, lauryl acrylate, hexafluorobutyl methacrylate, and hydroxyethyl methacrylate; the initiator is a mixture of one or more of azobisisobutyronitrile, benzoyl peroxide, and di-tert-butyl peroxide; the chain transfer agent is an aliphatic mercaptan or dodecyl mercaptan; the solvent is a mixture of one or more of propylene glycol butyl ether, xylene, trimethylolbenzene, and solvent gasoline; and the amine neutralizer is one or more of dimethylethanolamine, triethylamine, and ammonia water.

[0009] As a preferred embodiment of the above technical solution, in step (1), the mass ratio of the acrylic ester monomer, the initiator and the chain transfer agent in the mixed liquid is 1: (0.005-0.02): (0.01-0.02), and the mass ratio of the mixed liquid and the solvent added in the preparation of the core layer resin material is (2-3): (2-3).

[0010] As a preferred embodiment of the above technical solution, in step (1), the mass ratio of the remaining mixed solution in the shell layer solution to the acrylic ester monomer is (2-3):(1-2), and the mass ratio of the shell layer solution to the core layer resin material is (10-20):(15-25).

[0011] As a preferred embodiment of the above technical solution, in step (1), the amount of the mixed liquid added during the first insulation reaction during the reaction process is 45-55% of the total mixed liquid mass, the temperature of the first insulation reaction is 150-170°C, the time is 2-4h, and the temperature of the second insulation reaction is 150-170°C, the time is 2-4h.

[0012] As a preferred embodiment of the above technical solution, in step (1), the solid content of the aqueous hydroxylated acrylic dispersion is 43-45 wt %, and the hydroxyl content of the solid in the aqueous hydroxylated acrylic dispersion is 3.5-3.6 wt %.

[0013] As a preferred embodiment of the above technical solution, in step (2), the component A also includes waste marble powder and silicon oxide doped graphene oxide material. In component A, the amounts of each component are, by mass percentage, 50-70wt% of aqueous hydroxy acrylic dispersion, 0-20wt% of pigment and filler, 2-5wt% of waste marble powder, 2-3wt% of silicon oxide doped graphene oxide material, 1-5wt% of additive, and 10-20wt% of water.

[0014] As a preferred embodiment of the above technical solution, the preparation method of the silicon oxide doped graphene oxide material is: melamine and graphene oxide are added to deionized water in a mass ratio of (5-10):1, the temperature is raised to 70-90°C, and the mixture is stirred at 800-1500 rpm for 30-50 minutes, then cooled to room temperature, filtered, and the filtered precipitate is re-dispersed in deionized water to obtain a dispersion with a concentration of 5-7wt%, and then nano silicon oxide is added, ultrasonically treated, and finally vacuum dried to obtain the dispersion.

[0015] As a preferred embodiment of the above technical solution, in step (2), in component B, the aqueous isocyanate curing agent is a sulfonate-modified or silicone-modified isocyanate curing agent, the solvent is propylene glycol diacetate or propylene glycol methyl ether acetate, and in component B, the mass percentages of the aqueous isocyanate curing agent and the solvent are 40-80wt% and 20-60wt%, respectively.

[0016] As a preferred embodiment of the above technical solution, the mass ratio of component A to component B is (3-10):1.

[0017] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0018] The automotive water-based paint provided by the present invention comprises two components, A and B, wherein the A component comprises a water-based hydroxy acrylic dispersion, a pigment filler, waste marble powder and a silicon oxide doped graphene oxide material, and the B component comprises a water-based isocyanate curing agent and a solvent. The present invention uses the independently prepared water-based hydroxy acrylic dispersion in the paint, effectively reducing the preparation cost of the water-based paint, and the waste marble powder has high wear resistance, which can effectively improve the wear resistance of the paint, and the waste marble powder can play a buffering role, which can help the paint better resist the impact of impact and vibration, reduce damage to the paint surface, and improve the impact resistance of the paint. Silicon oxide and graphene oxide are doped and added to the paint to effectively improve the dispersibility of silicon oxide and graphene oxide in the paint, silicon oxide has high hardness and wear resistance, and adding it to the paint can improve the durability and wear resistance of the coating, and silicon oxide can effectively absorb and scatter ultraviolet rays, thereby reducing the penetration and destructive effects of ultraviolet rays, thereby further improving the weather resistance of the paint, and silicon oxide can also improve the adhesion of the paint, increase the bonding force between the coating and the substrate, and then improve the durability of the paint coating. Graphene oxide mainly improves the durability of paint coatings from the following aspects: First, graphene oxide has good oxidation resistance, and can effectively resist the process of oxidation and deterioration of the coating, thereby extending the service life of the coating; second, graphene oxide added to the coating can improve the corrosion resistance of the coating, reduce the penetration of chemical substances such as water and acids and alkalis, thereby extending the service life of the coating; third, graphene oxide can effectively absorb and scatter ultraviolet rays, thereby reducing the penetration and destructive effects of ultraviolet rays and extending the life of the coating. In addition, graphene oxide can also improve the mechanical strength and hardness of the paint coating. In summary, the water-based paint provided by the present invention not only has good stability, but also has strong adhesion and good weather resistance, and can cope with various harsh environments.

[0019] The present invention firstly uses acrylate monomers, initiators and chain transfer agents as raw materials through prepolymerization to prepare a water-based hydroxy acrylic dispersion with a core-shell structure, then mixes the dispersion with pigments, fillers, additives and the like to prepare component A, and uses a water-based isocyanate curing agent and a solvent as raw materials to prepare component B. The prepared automotive water-based paint has not only excellent weather resistance, but also good mechanical properties and excellent bonding performance with a substrate. The method provided by the present invention is simple to operate, has low paint preparation cost, and the prepared paint has excellent performance. Specific implementation method:

[0020] In order to better understand the present invention, the present invention is further described below by way of examples. The examples are only used to explain the present invention and will not constitute any limitation to the present invention.

[0021] Example 1

[0022] (1) Preparation of water-based hydroxylated acrylic dispersion:

[0023] Add 20wt% of propylene glycol butyl ether, which accounts for a percentage of the total production volume, into a reaction device, and heat it to 150°C; mix 15wt% of methyl methacrylate, 15wt% of n-butyl methacrylate, 20wt% of hydroxyethyl methacrylate, 1wt% of di-tert-butyl peroxide, and 1wt% of dodecyl mercaptan in a container to obtain a mixed solution, and drip 50wt% of the mixed solution into the reaction device at a constant speed, control the dripping time to be 2h, and keep the temperature at 150°C for 2h after the dripping is completed to obtain a core layer resin material; add 20wt% of acrylic acid to the remaining mixed solution, stir it evenly, and then drip it into the reaction device at a constant speed, control the dripping time to be 2h, and keep the temperature at 150°C for 2h after the dripping is completed to react, cool it to room temperature after the reaction is completed, neutralize it with dimethylethanolamine, and then slowly add deionized water to adjust the solid content to obtain an aqueous hydroxy acrylic acid dispersion with a core-shell structure having a solid content of 43wt%;

[0024] (2) Preparation of water-based environmentally friendly and highly weather-resistant water-based automotive topcoat:

[0025] In terms of mass percentage, 60wt% of the above-prepared aqueous hydroxy acrylic dispersion, 15wt% of water, 2wt% of aqueous dispersant, 0.3wt% of aqueous defoamer, 25wt% of rutile titanium dioxide, and 0.5wt% of aqueous bentonite are mixed evenly and ground to a fineness of less than 10μm, 6wt% of aqueous film-forming aid, 0.5wt% of aqueous substrate wetting agent, 0.5wt% of aqueous leveling agent, and 2wt% of associative polyurethane thickener are added, and dispersed evenly to obtain a high-gloss white automotive topcoat component A; a silicone-modified isocyanate curing agent is dispersed in a PGDA solvent at a ratio of 70wt% to obtain a high-gloss white automotive topcoat component B, and component A and component B are mixed at a mass ratio of 4:1 to obtain a coating.

[0026] Example 2

[0027] (1) The preparation process of the aqueous hydroxylated acrylic acid dispersion is the same as that of Example 1;

[0028] (2) In terms of mass percentage, 70 wt % of the aqueous hydroxy acrylic dispersion prepared above, 10 wt % of water, 2 wt % of an aqueous dispersant, 0.3 wt % of an aqueous defoamer, 2 wt % of a high-pigment carbon black powder, and 0.5 wt % of an aqueous bentonite are mixed and then ground to a fineness of less than 10 μm, 6 wt % of an aqueous film-forming aid, 0.1-0.5 wt % of an aqueous substrate wetting agent, 0.1 wt % of an aqueous leveling agent, and 2 wt % of an associative polyurethane thickener are added, and the mixture is dispersed uniformly to obtain a high-gloss black automotive topcoat component A; a silicone-modified isocyanate curing agent is dispersed in a PGDA solvent at a ratio of 50 wt % to obtain a high-gloss black automotive topcoat component B, and component A and component B are mixed at a mass ratio of 4:1 to obtain a coating.

[0029] Example 3

[0030] (1) The preparation process of the aqueous hydroxylated acrylic acid dispersion is the same as that of Example 1;

[0031] (2) In terms of mass percentage, 65 wt% of the aqueous hydroxy acrylic dispersion prepared above, 13 wt% of water, 2 wt% of an aqueous dispersant, 0.2 wt% of an aqueous defoamer, 5 wt% of an aqueous film-forming aid, 0.4 wt% of an aqueous substrate wetting agent, 0.3 wt% of an aqueous leveling agent, and 2 wt% of an associative polyurethane thickener are uniformly dispersed to obtain a component A of an automotive topcoat varnish; a silicone-modified isocyanate curing agent is dispersed in a PGDA solvent at a ratio of 60 wt% to obtain a coating component B, and the components A and B are mixed at a mass ratio of 4:1 to obtain a coating.

[0032] Example 4

[0033] (1) The preparation process of the aqueous hydroxylated acrylic acid dispersion is the same as that of Example 1;

[0034] (2) 2 g of melamine and 0.25 g of graphene oxide were added to 50 ml of deionized water and heated to 80° C. The mixture was stirred at 1000 rpm for 40 min, then cooled to room temperature, filtered, and the filtered precipitate was redispersed in deionized water to obtain a dispersion with a concentration of 6 wt%, and then 0.2 g of nano-titanium oxide was added, ultrasonically treated at 500 W for 30 min, and finally vacuum dried to obtain a silicon oxide-doped graphene oxide material.

[0035] (2) In terms of mass percentage, 65 wt% of the aqueous hydroxy acrylic dispersion prepared above, 15 wt% of water, 2.5 wt% of an aqueous dispersant, 0.2 wt% of an aqueous defoamer, 3 wt% of high-pigment carbon black powder, 2 wt% of waste marble powder, 2 wt% of a silicon oxide-doped graphene oxide material, and 0.2 wt% of an aqueous bentonite are mixed and then ground to a fineness of less than 10 μm, 5 wt% of an aqueous film-forming aid, 0.2 wt% of an aqueous substrate wetting agent, 0.5 wt% of an aqueous leveling agent, and 2 wt% of an associative polyurethane thickener are added, and the mixture is dispersed uniformly to obtain a high-gloss black automotive topcoat component A; an organosilicon-modified isocyanate curing agent is dispersed in a PGDA solvent at a ratio of 65 wt% to obtain a high-gloss black automotive topcoat component B, and component A and component B are mixed at a mass ratio of 4:1 to obtain a coating.

[0036] The coatings prepared in the above examples were subjected to performance tests, and the test results are shown in Table 1.

[0037] Table 1

[0038]

[0039]

[0040] It can be seen from the above test results that the coating prepared by the present invention not only has high hardness, but also has good bonding with the substrate, excellent mechanical properties and good weather resistance.

[0041] In addition, it should be understood that after reading the contents of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat, characterized in that: The following steps are involved: (1) an acrylate monomer, an initiator and a chain transfer agent are mixed to obtain a mixed solution, a solvent is added to a reactor and the temperature is increased, then a portion of the mixed solution is added to the reactor, a first heat preservation reaction is performed to obtain a core layer resin material, acrylic acid is added to the remaining mixed solution, the mixture is mixed to obtain a shell layer solution, the shell layer solution is added to the core layer resin material, a second heat preservation reaction is performed, after the reaction is completed, the mixture is cooled to room temperature, an amine neutralizer is slowly added to the reaction solution for neutralization, and deionized water is added to adjust the solid content of the reaction solution to obtain an aqueous hydroxy acrylic dispersion having a core-shell structure; (2) The aqueous hydroxy acrylic dispersion, pigments, fillers, additives and water prepared above are mixed and ground evenly to prepare component A, and the aqueous isocyanate curing agent and solvent are mixed evenly to prepare component B; The component A also includes waste marble powder and silicon oxide doped graphene oxide material. In the component A, the amounts of the components are 50-70wt% of waterborne hydroxy acrylic dispersion, 0-20wt% of pigments and fillers, 2-5wt% of waste marble powder, 2-3wt% of silicon oxide doped graphene oxide material, 1-5wt% of additives, and 10-20wt% of water, respectively. The preparation method of the silicon oxide doped graphene oxide material is as follows: melamine and graphene oxide are added to deionized water in a mass ratio of (5-10):1, the temperature is raised to 70-90°C, and the mixture is stirred at 800-1500 rpm for 30-50 minutes, then cooled to room temperature, filtered, and the filtered precipitate is re-dispersed in deionized water to obtain a dispersion with a concentration of 5-7wt%, and then nano silicon oxide is added, ultrasonic treatment is performed, and finally vacuum drying is performed to obtain the dispersion.

2. The method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat according to claim 1, characterized in that: In step (1), the acrylic ester monomer is a mixture of one or more of methyl methacrylate, n-butyl methacrylate, isooctyl acrylate, lauryl acrylate, hexafluorobutyl methacrylate, and hydroxyethyl methacrylate; the initiator is a mixture of one or more of azobisisobutyronitrile, benzoyl peroxide, and di-tert-butyl peroxide; the chain transfer agent is an aliphatic mercaptan; the solvent is a mixture of one or more of propylene glycol butyl ether, xylene, trimethylbenzene, and solvent gasoline; and the amine neutralizer is one or more of dimethylethanolamine, triethylamine, and ammonia water.

3. The method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat according to claim 1, characterized in that: In step (1), the mass ratio of the acrylic ester monomer, the initiator and the chain transfer agent in the mixed liquid is 1: (0.005-0.02): (0.01-0.02), and the mass ratio of the mixed liquid and the solvent added in the preparation of the core layer resin material is (2-3): (2-3).

4. The method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat according to claim 1, characterized in that: In step (1), the mass ratio of the remaining mixed solution in the shell layer solution to acrylic acid is (2-3):(1-2), and the mass ratio of the shell layer solution to the core layer resin material is (10-20):(15-25).

5. The method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat according to claim 1, characterized in that: In step (1), the amount of the mixed solution added during the first insulation reaction during the reaction process is 45-55% of the total mixed solution mass, the temperature of the first insulation reaction is 150-170°C, the time is 2-4h, and the temperature of the second insulation reaction is 150-170°C, the time is 2-4h.

6. The method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat according to claim 1, characterized in that: In step (1), the solid content of the aqueous hydroxylated acrylic dispersion is 43-45 wt %, and the hydroxyl content of the solid in the aqueous hydroxylated acrylic dispersion is 3.5-3.6 wt %.

7. The method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat according to claim 1, characterized in that: In step (2), in component B, the water-based isocyanate curing agent is a sulfonate-modified or silicone-modified isocyanate curing agent, and the solvent is propylene glycol diacetate or propylene glycol methyl ether acetate. In component B, the mass percentages of the water-based isocyanate curing agent and the solvent are 40-80wt% and 20-60wt%, respectively.

8. The method for preparing an environmentally friendly and highly weather-resistant water-based automotive topcoat according to claim 1, characterized in that: The mass ratio of component A to component B is (3-10):1.

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