Automobile repair paint and method for producing the same

Abstract

The application discloses an automobile repair paint and a preparation method thereof, and belongs to the technical field of coating. The automobile repair paint is used for solving the technical problem that the drying performance and wear resistance of the automobile repair paint in the prior art need to be improved. The preparation method of the automobile repair paint comprises the following steps: mixing water, modified epoxy resin, a leveling agent, quartz powder, nano calcium carbonate, an ultraviolet absorber and a defoaming agent, stirring, adding a curing agent, and uniformly mixing to obtain the automobile repair paint. The automobile repair paint prepared by the application has good drying performance and wear resistance, and also has excellent adhesion and prevents cracking. The good weather resistance is favorable for prolonging the service life.

Description

Technical Field

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

[0002] In modern transportation systems, automobiles have become an indispensable tool for people's travel. However, during daily use, car bodies inevitably suffer various types of damage, such as scratches and bumps. These seemingly insignificant problems actually have far-reaching effects, not only damaging the car's original appearance but also potentially accelerating corrosion due to damage to the protective layer on the car's surface, thus threatening the overall performance and lifespan of the vehicle. To effectively address this common problem, automotive repair paint has emerged and plays a crucial role in the automotive repair field. It can effectively repair damage to the car's surface, restoring the car's original appearance. At the same time, high-quality repair paint can also form a protective layer, preventing further damage to the car body from the external environment and extending the car's lifespan. In the automotive repair field, automotive repair paint needs to withstand the friction, ultraviolet radiation, and various climatic conditions of daily use. Furthermore, through scientific formulation and strict process control, high-quality repair paint not only ensures the appearance repair effect and provides long-term protection, meeting the dual needs of car owners for vehicle aesthetics and practicality, but also takes into account environmental impact, thus achieving a balance between performance and sustainability.

[0003] Chinese patent CN101787098B discloses a method for preparing acrylate hybrid emulsions and their applications. The method involves synthesizing acrylate hybrid emulsions using a seed emulsion polymerization process combined with immediate neutralization and a segmented dropwise addition process of polar monomers. Waterborne two-component polyurethane coatings prepared using this invention exhibit excellent water resistance, solvent resistance, high hardness, and abrasion resistance. The specification states that the surface drying time of the waterborne two-component polyurethane coating is 1 hour, but the drying time needs improvement, and automotive repair paints require good abrasion resistance. Summary of the Invention

[0004] The purpose of this invention is to provide an automotive repair paint and its preparation method, which solves the technical problem that the drying performance of automotive repair paint in the prior art needs to be improved while possessing good wear resistance.

[0005] To achieve the above objectives, the present invention provides a method for preparing automotive repair paint, comprising the following steps:

[0006] Mix water, modified epoxy resin, leveling agent, quartz powder, nano calcium carbonate, UV absorber and defoamer, stir, add curing agent, mix evenly to obtain automotive repair paint;

[0007] The preparation of modified epoxy resin includes the following steps:

[0008] Step (1) Mix deionized water, titanium dioxide and 3-aminopropyltriethoxysilane evenly, heat to react, filter, wash and dry to obtain amino-modified titanium dioxide.

[0009] Step (2) Mix epoxy resin, amino-modified titanium dioxide and hydrochloric acid aqueous solution, heat to react, after the reaction is completed, add acetone, filter, wash, and obtain titanium dioxide grafted epoxy resin.

[0010] Step (3) Tetrahydrofuran, methacrylic acid, titanium dioxide-grafted epoxy resin, 4-dimethylaminopyridine and dicyclohexylcarbodiimide are mixed evenly, heated to react, filtered and distilled under reduced pressure to obtain methacrylic acid-grafted epoxy resin.

[0011] Step (4) Mix isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier and water, stir evenly, add methacrylic acid grafted epoxy resin, continue stirring, add initiator, heat to react, after the reaction is completed, adjust pH, strip under reduced pressure and nitrogen gas, cool to room temperature to obtain modified epoxy resin.

[0012] Preferably, the mass ratio of water, modified epoxy resin, leveling agent, quartz powder, nano calcium carbonate, ultraviolet absorber, defoamer and curing agent is (20-40):(60-80):(1-2):(4-6):(5-9):(1-3):(0.3-0.7):(15-25).

[0013] Preferably, in step (1), the mass ratio of deionized water, titanium dioxide and 3-aminopropyltriethoxysilane is (1000-1600):(60-80):(45-65).

[0014] Preferably, in step (1), the reaction temperature is 60-80℃ and the reaction time is 2-4h.

[0015] Preferably, in step (2), the mass ratio of epoxy resin, amino-modified titanium dioxide, hydrochloric acid aqueous solution and acetone is (1000-1600):(80-100):(2000-3600):(5000-7000), and the concentration of hydrochloric acid aqueous solution is 0.01 mol / L.

[0016] Preferably, in step (2), the reaction temperature is 70-90℃ and the reaction time is 1.5-2.5h.

[0017] Preferably, in step (3), the mass ratio of tetrahydrofuran, methacrylic acid, titanium dioxide-grafted epoxy resin, 4-dimethylaminopyridine and dicyclohexylcarbodiimide is (3000-5000):(40-60):(1200-2000):(6-10):(90-120).

[0018] Preferably, in step (3), the reaction temperature is 30-40℃ and the reaction time is 2-4h.

[0019] Preferably, in step (4), the mass ratio of isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier, water, methacrylate-grafted epoxy resin and initiator is (45-55):(9-11):(28-32):(19-21):(3.5-4.5):(240-260):(35-45):(1.5-2.5).

[0020] Preferably, in step (4), the reaction temperature is 50-70℃ and the reaction time is 3-5h.

[0021] Preferably, the curing agent is a fatty amine curing agent.

[0022] Preferably, the emulsifier is a geminal quaternary ammonium salt.

[0023] Preferably, the leveling agent is either Tego-450 or BYK-333.

[0024] Preferably, the defoamer is BYK-024.

[0025] Preferably, the initiator is V50.

[0026] Preferably, the process parameters for stripping under reduced pressure and nitrogen gas introduction are: stripping at 0.08-0.09 MPa for 1-2 hours with nitrogen gas introduction, and nitrogen gas flow rate of 0.5-1 L / min.

[0027] An automotive repair paint prepared using the aforementioned method.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. The titanium dioxide used in this invention is an inorganic material that can effectively absorb and scatter ultraviolet (UV) radiation. Its UV resistance principle mainly includes two aspects: first, absorbing UV radiation and converting it into heat energy; and second, enhancing UV resistance by scattering UV radiation. Simultaneously, due to its small size, modification of titanium dioxide effectively prevents agglomeration, allowing for uniform dispersion and maintaining its functional stability. Furthermore, its addition to the matrix increases wear resistance and improves matrix properties. Amino-modified titanium dioxide is covalently bonded to epoxy resin, ensuring uniform dispersion of inorganic nanoparticle titanium dioxide within the resin matrix.

[0030] 2. This invention utilizes a UV absorber and titanium dioxide to synergistically form an anti-UV barrier, reducing UV damage and improving durability. The introduction of trifluoroethyl methacrylate imparts a "low surface energy protective layer" to the paint film. The strong electronegativity of its fluorine atoms forms a dense hydrophobic and oleophobic layer on the paint film surface, reducing water adhesion and penetration. Furthermore, its high CF bond energy makes it difficult for UV energy to damage the CF bonds, thus extending the lifespan of the paint film. In this invention, the carboxyl groups in methacrylic acid undergo esterification with the hydroxyl groups in titanium dioxide-grafted epoxy resin to obtain methacrylic acid-grafted epoxy resin. Because the methacrylic acid-grafted epoxy resin contains unsaturated carbon-carbon double bonds, it can react with isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, and styrene under the action of an initiator to obtain modified epoxy resin. The introduced methacrylic acid increases the polarity of the epoxy resin, and its subsequent free radical reaction with acrylate substances regulates flexibility, making the paint film less prone to peeling due to internal stress during alternating hot and cold temperatures, further strengthening adhesion. The benzene rings in styrene possess a certain degree of rigidity, which increases the hardness of the paint film and improves wear resistance. Modified epoxy resins, under the action of a curing agent, rapidly form a network cross-linked structure; the higher the degree of cross-linking, the better the weather resistance.

[0031] 3. In this invention, quartz powder, as a high-hardness inorganic filler, is uniformly dispersed in the paint film, increasing wear resistance and directly resisting the cutting action of external friction on the paint film surface. Nano-calcium carbonate fills the pores, further improving the density of the paint film. The long-chain alkyl groups of isooctyl methacrylate and butyl methacrylate impart a certain degree of flexibility to the matrix, allowing the paint film to absorb energy through slight deformation when subjected to impact and friction, avoiding rigid fracture. Meanwhile, the styrene units ensure the overall hardness of the paint film, preventing excessive deformation that leads to accelerated wear. This structure makes the paint film less prone to wear-through during repeated friction and less prone to failure due to brittle cracking. In addition, epoxy resin has good adhesion and water solubility, significantly improving the interfacial bonding force with the substrate. High adhesion ensures that the wear-resistant particles and resin, and the paint film and substrate, do not delaminate due to frictional stress, while the high-density cross-linked structure formed by rapid drying avoids pore defects inside the paint film, further improving wear resistance.

[0032] 4. The automotive repair paint provided by this invention has excellent adhesion and weather resistance, effectively coping with various harsh environmental conditions. Its preparation process is not only simple and efficient, but also ensures high gloss and good leveling properties of the paint film. Furthermore, by optimizing the proportions of each component in the formula, this repair paint further enhances the hardness and flexibility of the paint film, giving it broader application prospects in the automotive repair field. Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a method for preparing automotive repair paint, including the following steps:

[0036] Mix water, modified epoxy resin, BYK-333, quartz powder, nano calcium carbonate, UV absorber and BYK-024, stir, add curing agent, mix evenly to obtain automotive repair paint;

[0037] The mass ratio of water, modified epoxy resin, BYK-333, quartz powder, nano calcium carbonate, ultraviolet absorber, BYK-024 and curing agent is 20:60:1:4:5:1:0.3:15.

[0038] The preparation of modified epoxy resin includes the following steps:

[0039] Step (1) Deionized water, titanium dioxide and 3-aminopropyltriethoxysilane were mixed evenly in a mass ratio of 1000:60:45 and reacted at 60°C for 4 hours. After the reaction was completed, the mixture was filtered, washed three times with deionized water, and dried at 80°C for 5 hours to obtain amino-modified titanium dioxide.

[0040] Step (2) Mix epoxy resin, amino-modified titanium dioxide and 0.01 mol / L hydrochloric acid aqueous solution, react at 70℃ for 2.5 h, after the reaction is completed, add acetone, filter, wash 3 times with deionized water to obtain titanium dioxide grafted epoxy resin.

[0041] The mass ratio of epoxy resin, amino-modified titanium dioxide, hydrochloric acid aqueous solution and acetone is 1000:80:2000:5000.

[0042] Step (3) Tetrahydrofuran, methacrylic acid, titanium dioxide-grafted epoxy resin, 4-dimethylaminopyridine and dicyclohexylcarbodiimide are mixed in a mass ratio of 3000:40:1200:6:90, heated and reacted at 30°C for 4 hours. After the reaction is completed, the mixture is filtered and distilled under reduced pressure to obtain methacrylic acid-grafted epoxy resin.

[0043] Step (4) Mix isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier and water, stir evenly, add methacrylic acid grafted epoxy resin, continue stirring, add initiator V50, heat to 50℃ and react for 5h, after the reaction is completed, adjust pH to 8, introduce nitrogen gas at 0.08MPa and at a flow rate of 0.5L / min, and strip for 2h, cool to room temperature to obtain modified epoxy resin;

[0044] The mass ratio of isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier, water, methacrylic acid grafted epoxy resin and V50 is 45:9:28:19:3.5:240:35:1.5.

[0045] Example 2

[0046] This embodiment provides a method for preparing automotive repair paint, including the following steps:

[0047] Mix water, modified epoxy resin, BYK-333, quartz powder, nano calcium carbonate, UV absorber and BYK-024, stir, add curing agent, mix evenly to obtain automotive repair paint;

[0048] The mass ratio of water, modified epoxy resin, BYK-333, quartz powder, nano calcium carbonate, UV absorber, BYK-024 and curing agent is 25:65:1.2:4.5:6:1.5:0.4:17.

[0049] The preparation of modified epoxy resin includes the following steps:

[0050] Step (1) Deionized water, titanium dioxide and 3-aminopropyltriethoxysilane were mixed evenly in a mass ratio of 1150:65:50 and reacted at 65°C for 3.5 h. After the reaction was completed, the mixture was filtered, washed three times with deionized water, and dried at 85°C for 4.5 h to obtain amino-modified titanium dioxide.

[0051] Step (2) Mix epoxy resin, amino-modified titanium dioxide and 0.01 mol / L hydrochloric acid aqueous solution, react at 75℃ for 2.2 h, after the reaction is completed, add acetone, filter, wash 3 times with deionized water to obtain titanium dioxide grafted epoxy resin.

[0052] The mass ratio of epoxy resin, amino-modified titanium dioxide, hydrochloric acid aqueous solution and acetone is 1150:85:2400:5500.

[0053] Step (3) Tetrahydrofuran, methacrylic acid, titanium dioxide-grafted epoxy resin, 4-dimethylaminopyridine and dicyclohexylcarbodiimide are mixed in a mass ratio of 3500:45:1400:7:97, heated and reacted at 32°C for 3.5 h. After the reaction is completed, the mixture is filtered and distilled under reduced pressure to obtain methacrylic acid-grafted epoxy resin.

[0054] Step (4) Mix isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier and water, stir evenly, add methacrylic acid grafted epoxy resin, continue stirring, add initiator V50, heat to 55℃ and react for 4.5h, after the reaction is completed, adjust pH to 8, introduce nitrogen gas at 0.08MPa and a flow rate of 0.6L / min, and strip for 1.8h, cool to room temperature to obtain modified epoxy resin;

[0055] The mass ratio of isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier, water, methacrylic acid grafted epoxy resin and V50 is 47:9.5:29:19.5:3.7:245:37:1.7.

[0056] Example 3

[0057] This embodiment provides a method for preparing automotive repair paint, including the following steps:

[0058] Mix water, modified epoxy resin, BYK-333, quartz powder, nano calcium carbonate, UV absorber and BYK-024, stir, add curing agent, mix evenly to obtain automotive repair paint;

[0059] The mass ratio of water, modified epoxy resin, BYK-333, quartz powder, nano calcium carbonate, ultraviolet absorber, BYK-024 and curing agent is 30:70:1.5:5:7:2:0.5:20.

[0060] The preparation of modified epoxy resin includes the following steps:

[0061] Step (1) Deionized water, titanium dioxide and 3-aminopropyltriethoxysilane were mixed evenly in a mass ratio of 1300:70:55 and reacted at 70°C for 3 hours. After the reaction was completed, the mixture was filtered, washed three times with deionized water, and dried at 90°C for 4 hours to obtain amino-modified titanium dioxide.

[0062] Step (2) Mix epoxy resin, amino-modified titanium dioxide and 0.01 mol / L hydrochloric acid aqueous solution, react at 80℃ for 2 h, after the reaction is completed, add acetone, filter, wash 3 times with deionized water to obtain titanium dioxide grafted epoxy resin.

[0063] The mass ratio of epoxy resin, amino-modified titanium dioxide, hydrochloric acid aqueous solution and acetone is 1300:90:2800:6000.

[0064] Step (3) Tetrahydrofuran, methacrylic acid, titanium dioxide-grafted epoxy resin, 4-dimethylaminopyridine and dicyclohexylcarbodiimide are mixed in a mass ratio of 4000:50:1600:8:105, heated and reacted at 35°C for 3 hours. After the reaction is completed, the mixture is filtered and distilled under reduced pressure to obtain methacrylic acid-grafted epoxy resin.

[0065] Step (4) Mix isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier and water, stir evenly, add methacrylic acid grafted epoxy resin, continue stirring, add initiator V50, heat to 60℃ and react for 4h, after the reaction is completed, adjust pH to 8, introduce nitrogen gas at 0.08MPa and at a flow rate of 0.7L / min, and strip for 1.5h, cool to room temperature to obtain modified epoxy resin;

[0066] The mass ratio of isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier, water, methacrylic acid grafted epoxy resin and V50 is 50:10:30:20:4:250:40:2.

[0067] Example 4

[0068] This embodiment provides a method for preparing automotive repair paint, including the following steps:

[0069] Mix water, modified epoxy resin, BYK-333, quartz powder, nano calcium carbonate, UV absorber and BYK-024, stir, add curing agent, mix evenly to obtain automotive repair paint;

[0070] The mass ratio of water, modified epoxy resin, BYK-333, quartz powder, nano calcium carbonate, ultraviolet absorber, BYK-024 and curing agent is 35:75:1.8:5.5:8:2.5:0.6:22.

[0071] The preparation of modified epoxy resin includes the following steps:

[0072] Step (1) Deionized water, titanium dioxide and 3-aminopropyltriethoxysilane were mixed evenly in a mass ratio of 1450:75:60 and reacted at 75°C for 2.5 h. After the reaction was completed, the mixture was filtered, washed three times with deionized water, and dried at 95°C for 3.5 h to obtain amino-modified titanium dioxide.

[0073] Step (2) Mix epoxy resin, amino-modified titanium dioxide and 0.01 mol / L hydrochloric acid aqueous solution, react at 85℃ for 1.7 h, after the reaction is completed, add acetone, filter, wash 3 times with deionized water to obtain titanium dioxide grafted epoxy resin.

[0074] The mass ratio of epoxy resin, amino-modified titanium dioxide, hydrochloric acid aqueous solution and acetone is 1450:95:3200:6500.

[0075] Step (3) Tetrahydrofuran, methacrylic acid, titanium dioxide-grafted epoxy resin, 4-dimethylaminopyridine and dicyclohexylcarbodiimide are mixed in a mass ratio of 4500:55:1800:9:112, heated and reacted at 37°C for 2.5 h. After the reaction is completed, the mixture is filtered and distilled under reduced pressure to obtain methacrylic acid-grafted epoxy resin.

[0076] Step (4) Mix isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier and water, stir evenly, add methacrylic acid grafted epoxy resin, continue stirring, add initiator V50, heat to 65℃ and react for 3.5h, after the reaction is completed, adjust pH to 8, introduce nitrogen gas at 0.09MPa and at a flow rate of 0.8L / min, and strip for 1.2h, cool to room temperature to obtain modified epoxy resin;

[0077] The mass ratio of isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier, water, methacrylic acid grafted epoxy resin and V50 is 52:10.5:31:20.5:4.2:255:42:2.2.

[0078] Example 5

[0079] This embodiment provides a method for preparing automotive repair paint, including the following steps:

[0080] Mix water, modified epoxy resin, BYK-333, quartz powder, nano calcium carbonate, UV absorber and BYK-024, stir, add curing agent, mix evenly to obtain automotive repair paint;

[0081] The mass ratio of water, modified epoxy resin, BYK-333, quartz powder, nano calcium carbonate, ultraviolet absorber, BYK-024 and curing agent is 40:80:2:6:9:3:0.7:25.

[0082] The preparation of modified epoxy resin includes the following steps:

[0083] Step (1) Deionized water, titanium dioxide and 3-aminopropyltriethoxysilane were mixed evenly in a mass ratio of 1600:80:65 and reacted at 80°C for 2 hours. After the reaction was completed, the mixture was filtered, washed three times with deionized water, and dried at 100°C for 3 hours to obtain amino-modified titanium dioxide.

[0084] Step (2) Mix epoxy resin, amino-modified titanium dioxide and 0.01 mol / L hydrochloric acid aqueous solution, react at 90℃ for 1.5 h, after the reaction is completed, add acetone, filter, wash 3 times with deionized water to obtain titanium dioxide grafted epoxy resin.

[0085] The mass ratio of epoxy resin, amino-modified titanium dioxide, hydrochloric acid aqueous solution and acetone is 1600:100:3600:7000.

[0086] Step (3) Tetrahydrofuran, methacrylic acid, titanium dioxide-grafted epoxy resin, 4-dimethylaminopyridine and dicyclohexylcarbodiimide are mixed in a mass ratio of 5000:60:2000:10:120, heated and reacted at 40°C for 2 hours. After the reaction is completed, the mixture is filtered and distilled under reduced pressure to obtain methacrylic acid-grafted epoxy resin.

[0087] Step (4) Mix isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier and water, stir evenly, add methacrylic acid grafted epoxy resin, continue stirring, add initiator V50, heat to 70℃ and react for 3h, after the reaction is completed, adjust pH to 8, 0.09MPa, nitrogen gas is introduced at a flow rate of 1L / min and stripped for 1h, cool to room temperature to obtain modified epoxy resin;

[0088] The mass ratio of isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier, water, methacrylic acid grafted epoxy resin and V50 is 55:11:32:21:4.5:260:45:2.5.

[0089] Comparative Example 1

[0090] The difference between this comparative example and Example 1 is that the trifluoroethyl methacrylate in step (4) is replaced with an equal amount of water.

[0091] Comparative Example 2

[0092] The difference between this comparative example and Example 1 is that step (4) is omitted, and the modified epoxy resin is replaced with an equal mass of methacrylic acid grafted epoxy resin.

[0093] Comparative Example 3

[0094] The difference between this comparative example and Example 1 is that steps (3) and (4) are omitted, and the modified epoxy resin is replaced with an equal mass of titanium dioxide-grafted epoxy resin.

[0095] Comparative Example 4

[0096] This comparative example is the weather-resistant automotive repair clear coat disclosed in Example 4 of Chinese patent application CN109161324B.

[0097] Comparative Example 5

[0098] This comparative example is the ultra-fast drying water-based clear coat for automotive repair disclosed in Example 3 of Chinese patent application CN114525075B.

[0099] In the embodiments and comparative examples 1-3 of this invention, the epoxy resin is Phoenix brand E-44 bisphenol A type epoxy resin, sourced from Shenyang Xinmaofa Fine Chemical Raw Materials Co., Ltd.; the curing agent is... 2771 fatty amine, from Shandong Tunan New Materials Co., Ltd.; emulsifier 31524, a Gemini quaternary ammonium salt, from Zhengzhou Yihe Fine Chemicals Co., Ltd.; initiator V50 and acetone, both from Sinopharm Chemical Reagent Co., Ltd.; UV absorber, UV-1130, from Dongguan Kangjin New Materials Technology Co., Ltd.; BYK-024, from Guangzhou Yitong Polymer Materials Co., Ltd.; BYK-333, from BAK (Germany); titanium dioxide, JR05, with an average particle size of 5nm, from Xuancheng Jingrui New Materials Co., Ltd.; quartz powder, from Wuhan Jiyesheng Chemical Co., Ltd.; nano calcium carbonate, from Ningbo Luofei Nanotechnology Co., Ltd.; and all other products are commercially available.

[0100] Performance testing:

[0101] The automotive refinish paints in Examples 1-5 and Comparative Examples 1-5 were tested accordingly, and the test results are shown below:

[0102] (1) Drying performance test: The drying time was tested in accordance with the relevant standard of "HG / T 5061-2016 Coatings for Automotive Repair". The test was repeated 3 times and the average value was recorded. The specific test results are shown in Table 1.

[0103] (2) Hardness test: Refer to "GBT 6739-2006 Pencil method for determining the hardness of paint film", the test results are shown in Table 1;

[0104] (3) Abrasion resistance test: The test standard refers to GB / T1768-89. The machine is a MI type paint film abrasion tester. The weight of the weight is 500g. The test speed is 1000 revolutions. The test is repeated 3 times. The average value is recorded. The test results are shown in Table 1.

[0105] (4) Adhesion test: determined in accordance with national standard GB / T 9286-1998;

[0106] (5) DOI value and gloss test: The sharpness (DOI value) and gloss of the automotive repair paints in Examples 1-5 and Comparative Examples 1-5 were tested in accordance with the relevant standard of "HG / T 5061-2016 Coatings for Automotive Repair". The specific test results are shown in Table 1.

[0107] (6) Weather resistance test: The paint films corresponding to the automotive repair paints in Examples 1-5 and Comparative Examples 1-5 were tested. They were artificially accelerated aged under ultraviolet light for 5000 hours, and the gloss loss rate was recorded. The specific test results are shown in Table 1.

[0108] Table 1

[0109]

[0110] The results above show that the automotive repair paints in Examples 1-5 have good drying performance, adhesion, and abrasion resistance. When applied to the automotive repair field, the automotive repair paints prepared according to this invention also exhibit good film appearance and weather resistance, which helps extend service life. In Comparative Example 1, the lack of trifluoroethyl methacrylate (CFMA) reduces weather resistance, mainly because the CF bonds in CFMA have high bond energy and require high energy to break. In Comparative Example 2, the absence of acrylates further reduces drying performance, while the lack of CFMA reduces weather resistance. In Comparative Example 3, the use of titanium dioxide-grafted epoxy resin instead of modified epoxy resin reduces weather resistance and drying performance, but enhances adhesion. This is mainly because the epoxy resin content is higher than in Example 1, and the lack of styrene reduces hardness and abrasion resistance.

[0111] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0112] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0113] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing an automotive repair paint, characterized in that, Includes the following steps: Mix water, modified epoxy resin, leveling agent, quartz powder, nano calcium carbonate, UV absorber and defoamer, stir, add curing agent, mix evenly to obtain automotive repair paint; The preparation of modified epoxy resin includes the following steps: Step (1) Mix deionized water, titanium dioxide and 3-aminopropyltriethoxysilane evenly, heat to react, filter, wash and dry to obtain amino-modified titanium dioxide. Step (2) Mix epoxy resin, amino-modified titanium dioxide and hydrochloric acid aqueous solution, heat to react, after the reaction is completed, add acetone, filter, wash, and obtain titanium dioxide grafted epoxy resin. Step (3) Tetrahydrofuran, methacrylic acid, titanium dioxide-grafted epoxy resin, 4-dimethylaminopyridine and dicyclohexylcarbodiimide are mixed evenly, heated to react, filtered and distilled under reduced pressure to obtain methacrylic acid-grafted epoxy resin. Step (4) Mix isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier and water, stir evenly, add methacrylic acid grafted epoxy resin, continue stirring, add initiator, heat to react, after the reaction is completed, adjust pH, strip under reduced pressure and nitrogen gas, cool to room temperature to obtain modified epoxy resin.

2. The method for preparing an automotive repair paint according to claim 1, characterized in that, The mass ratio of water, modified epoxy resin, leveling agent, quartz powder, nano calcium carbonate, ultraviolet absorber, defoamer and curing agent is (20-40):(60-80):(1-2):(4-6):(5-9):(1-3):(0.3-0.7):(15-25).

3. The method for preparing an automotive repair paint according to claim 1, characterized in that, In step (1), the mass ratio of deionized water, titanium dioxide and 3-aminopropyltriethoxysilane is (1000-1600):(60-80):(45-65).

4. The method for preparing an automotive repair paint according to claim 1, characterized in that, In step (1), the reaction temperature is 60-80℃ and the reaction time is 2-4h.

5. The method for preparing an automotive repair paint according to claim 1, characterized in that, In step (2), the mass ratio of epoxy resin, amino-modified titanium dioxide, hydrochloric acid aqueous solution and acetone is (1000-1600):(80-100):(2000-3600):(5000-7000), and the concentration of hydrochloric acid aqueous solution is 0.01 mol / L.

6. The method for preparing an automotive repair paint according to claim 1, characterized in that, In step (2), the reaction temperature is 70-90℃ and the reaction time is 1.5-2.5h.

7. The method for preparing an automotive repair paint according to claim 1, characterized in that, In step (3), the mass ratio of tetrahydrofuran, methacrylic acid, titanium dioxide-grafted epoxy resin, 4-dimethylaminopyridine and dicyclohexylcarbodiimide is (3000-5000):(40-60):(1200-2000):(6-10):(90-120).

8. The method for preparing an automotive repair paint according to claim 1, characterized in that, In step (3), the reaction temperature is 30-40℃ and the reaction time is 2-4h.

9. The method for preparing an automotive repair paint according to claim 1, characterized in that, In step (4), the mass ratio of isooctyl methacrylate, trifluoroethyl methacrylate, butyl methacrylate, styrene, emulsifier, water, methacrylate-grafted epoxy resin and initiator is (45-55):(9-11):(28-32):(19-21):(3.5-4.5):(240-260):(35-45):(1.5-2.5).

10. The method for preparing an automotive repair paint according to claim 1, characterized in that, In step (4), the reaction temperature is 50-70℃ and the reaction time is 3-5h.

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