Coating for local spraying of carbon fiber composite material

Abstract

The invention relates to a coating for local spraying of a carbon fiber composite material, which is prepared from the following components in parts by weight: 56 to 78 parts of epoxy modified acrylic resin, 11 to 22 parts of modified filler, 0.2 to 0.6 part of dispersing agent, 0.1 to 0.5 part of defoaming agent, 0.1 to 0.5 part of flatting agent, 18 to 26 parts of curing agent and 40 to 60 parts of solvent. The coating prepared by the invention can be used for locally coating the surface of a carbon fiber workpiece, so that the problem of repairing the surface of the workpiece is solved, the problems of uneven surface, poor covering and the like of an adjusted area in the use process are avoided, and the overall process efficiency of coating is favorably improved.

Description

Technical Field

[0001] The invention relates to the field of carbon fiber, and in particular to a coating for local spraying of carbon fiber composite materials. Background Art

[0002] With the development of low-altitude economy, carbon fiber composite pipe fittings are becoming more and more popular in aerospace, military, wind power, automobile, medical, sports and other industries due to their light weight, high strength, high temperature resistance, abrasion resistance and corrosion resistance. Since the workpieces made of carbon fiber composite materials are used in structural parts, carbon fiber composite materials are required to have higher wear resistance, impermeability, corrosion resistance, etc., and higher requirements are put forward for the surface performance of carbon fiber materials. How to strengthen the surface of carbon fiber composite materials has become the research focus of carbon fiber application. Common surface treatment methods for carbon fiber usually include surface cleaning method, gas phase oxidation method, surface coating method, plasma treatment method, liquid phase oxidation method, etc. Painting on the surface of carbon fiber is one of the surface coating methods. Surface roughening and overall grinding of the workpiece are the main pre-treatment of the painting process, and then the painting curing treatment is carried out. The purpose is to solve the problems of the painting process of carbon fiber workpieces with large or complex surfaces, such as uneven surface, flow marks, exposed bottom, poor covering, orange peel and other phenomena. To solve the paint surface problems of carbon fiber composite workpieces, overall grinding and re-spraying are usually adopted to ensure the uniformity of the overall coating. However, spraying after overall grinding not only wastes manpower and time, but also may cause over-grinding of the workpiece, resulting in reduced performance of the workpiece. At the same time, the coating after coating often has poor adhesion on the coating surface and paint falls off after a long time. Summary of the invention

[0003] In view of the problems existing in the prior art, the object of the present invention is to provide a coating for local spraying of carbon fiber composite materials.

[0004] The purpose of the present invention is achieved by the following technical solutions:

[0005] In a first aspect, the present invention provides a coating for local spraying of carbon fiber composite materials, which comprises, calculated by weight:

[0006] 56-78 parts of epoxy modified acrylic resin, 11-22 parts of modified filler, 0.2-0.6 parts of dispersant, 0.1-0.5 parts of defoamer, 0.1-0.5 parts of leveling agent, 18-26 parts of curing agent and 40-60 parts of solvent.

[0007] Preferably, the preparation method of the epoxy-modified acrylic resin comprises:

[0008] Mix epoxy resin E-20 and ethylene glycol butyl ether, heat to 80-100°C under the protection of nitrogen, stir until completely dissolved, add a mixture of acrylic acid and half of the initiator dropwise, and control the dropping time to be 2-3h. After the dropping is completed, add the remaining half of the initiator, heat to 110-120°C, stir at this temperature for 2-3h, and cool to room temperature to obtain epoxy modified acrylic resin.

[0009] Preferably, during the preparation of the epoxy-modified acrylic resin, the mass volume ratio of epoxy resin E-20, acrylic acid and ethylene glycol butyl ether is (1-3) g: (24-48) g: (40-60) mL.

[0010] Preferably, in the preparation process of the epoxy-modified acrylic resin, the total amount of the initiator used is 1%-5% of the total mass of acrylic acid, and the initiator is one of benzoic acid peroxide, cumene hydroperoxide, and tert-butyl benzyl peroxide.

[0011] Preferably, the dispersant is one of TEGO-670, TEGO-760W and TEGO-755W.

[0012] Preferably, the defoaming agent is one of BYK-A525, BYK-A530, BYK-088 and BYK-1615.

[0013] Preferably, the leveling agent is an organic silicon leveling agent, and the model is one of HY-3510, HY-8110, HY-5057, and HY-1484.

[0014] Preferably, the curing agent is an HDI trimer curing agent, and the brand is one of Wanhua HT-100, Wanhua HT-600, and Tosoh HRX-90B.

[0015] Preferably, the solvent is one of ethyl acetate, butyl acetate, toluene and xylene.

[0016] Preferably, the preparation method of the modified filler is:

[0017] S1. Mix calcium boride powder and sodium hydroxide solution, stir in a water bath at 60-80°C for 3-5h, filter out the solid product, dry it to obtain active calcium boride; then disperse the active calcium boride in ethanol, add γ-glycidyloxypropyltrimethoxysilane (KH-560), reflux at 50-60°C for 6-10h, filter out the solid product, and dry it to obtain epoxylated calcium boride;

[0018] S2, adding tetrahydrofuran acrylate (THFA) and 4,6-diamino-2-mercaptopyrimidine (C4H6N4S) to N,N-dimethylformamide (DMF) in sequence, stirring until uniform, adding a photoinitiator, stirring under ultraviolet conditions for 1-2 hours, after the treatment is completed, removing the solvent, and drying to obtain a thioether compound;

[0019] S3. Mix the epoxylated calcium boride and the sulfide compound in anhydrous ethanol, add a few drops of triethylamine, raise the temperature to 70-80°C, condense and reflux for 4-6 hours, remove the solvent after the treatment, dry, and obtain a modified filler.

[0020] Preferably, in S1, the molecular formula of the calcium boride powder is CaB6, the purity is higher than 99%, and the particle size is 10-20 μm.

[0021] Preferably, in S1, the mass fraction of the sodium hydroxide solution is 10%-20%, and the mass volume ratio of the calcium boride powder to the sodium hydroxide solution is 1g:(15-25)mL.

[0022] Preferably, in S1, the mass volume ratio of active calcium boride, γ-glycidyloxypropyltrimethoxysilane and ethanol is 1 g: (0.15-0.35) g: (15-25) mL.

[0023] Preferably, in S2, the mass volume ratio of tetrahydrofuran acrylate, 4,6-diamino-2-mercaptopyrimidine and N,N-dimethylformamide is (0.26-0.52) g: (0.22-0.44) g: (10-20) mL.

[0024] Preferably, in S2, the photoinitiator is photoinitiator BDK, and the added amount is 2%-8% of the mass of 4,6-diamino-2-mercaptopyrimidine; the ultraviolet conditions are: ultraviolet lamp power 100-200W, irradiation distance 10-20cm.

[0025] Preferably, in S3, the mass volume ratio of epoxylated calcium boride, sulfide compound, triethylamine and anhydrous ethanol is 1 g: (0.37-0.59) g: (0.003-0.008) g: (20-30) mL.

[0026] In a second aspect, the present invention provides a method for preparing a coating for local spraying of carbon fiber composite materials, comprising:

[0027] Step 1, firstly mix the epoxy modified acrylic resin, the modified filler, the dispersant and the solvent, and stir them thoroughly until they are uniform;

[0028] Step 2, adding defoamer and leveling agent to the mixed solution of step 1, and stirring again;

[0029] Step 3, adding a curing agent to the mixed solution of step 2, stirring evenly, to obtain a coating that can be applied and used.

[0030] In a third aspect, the present invention provides an application of a coating for local spraying of a carbon fiber composite material. After the coating is sprayed locally on the carbon fiber composite material, it is baked at 70±5°C for 30-60 minutes.

[0031] The beneficial effects of the present invention are:

[0032] 1. The coating prepared by the present invention can be used for local coating on the surface of a carbon fiber workpiece, thereby repairing problems on the surface of the workpiece. During use, the adjustment area will not have problems such as surface unevenness and poor covering, which is beneficial to improving the overall process efficiency of the coating.

[0033] 2. The coating prepared by the present invention can be used for local polishing and painting on the surface of a carbon fiber workpiece. The sprayed paint film will not have flow marks, exposed bottom, poor covering, orange peel and the like. It not only has good adhesion, but also has high strength and durability, and can be used for a long time without falling off.

[0034] 3. The coating of the present invention uses epoxy modified acrylic resin prepared from epoxy resin E-20 and acrylic acid as the main ingredients, and the filler uses modified fillers prepared from epoxylated calcium boride and thioether compounds. The prepared coating has the advantages of high strength, strong adhesion and good weather resistance when applied on the surface of carbon fiber.

[0035] 4. In the preparation of modified fillers, the epoxylated calcium boride is first activated by alkaline solution and then grafted with epoxysilane to obtain epoxylated calcium boride; and the thioether compound is a thioether compound containing amino groups obtained by combining tetrahydrofuran acrylate containing unsaturated double bonds and 4,6-diamino-2-mercaptopyrimidine containing thiol groups to undergo click chemistry reaction; then, the thioether compound is cross-linked and fixed on the surface of calcium boride through an epoxy-amino group bonding reaction to finally obtain a core-shell coated modified filler.

[0036] 5. Since the surface coating layer of the modified filler contains not only sulfide groups but also tetrahydrofuran ester groups and pyrimidine groups, etc., it not only makes the modified filler more compatible with the resin, but also has a great impact on improving the performance of the coating. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0038] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0039] The present invention will be further described below in conjunction with the following examples.

[0040] Example 1

[0041] A coating for local spraying of carbon fiber composite materials, calculated by weight, comprising:

[0042] 67 parts of epoxy modified acrylic resin, 16 parts of modified filler, 0.4 parts of dispersant, 0.3 parts of defoamer, 0.2 parts of leveling agent, 22 parts of curing agent and 50 parts of solvent.

[0043] Wherein, the preparation method of epoxy modified acrylic resin comprises:

[0044] Mix epoxy resin E-20 and ethylene glycol butyl ether, heat to 90°C under the protection of nitrogen, stir until completely dissolved, add dropwise a mixture of acrylic acid and 1.5% benzoic acid peroxide by weight of acrylic acid, and control the dropping time to be 2.5 hours. After the dropping is completed, add the remaining 1.5% benzoic acid peroxide by weight of acrylic acid. The mass volume ratio of epoxy resin E-20, acrylic acid and ethylene glycol butyl ether is 2g:36g:50mL. Heat to 115°C, keep stirring for 2.5 hours, and cool to room temperature to obtain epoxy modified acrylic resin.

[0045] Among them, the dispersant is TEGO-670; the defoamer is BYK-A525; the leveling agent is the silicone leveling agent HY-3510; the curing agent is Wanhua HT-100HDI trimer curing agent; and the solvent is butyl acetate.

[0046] Wherein, the preparation method of the modified filler is:

[0047] S1. Mix calcium boride powder (CaB6, purity higher than 99%, particle size 10-20 μm) and 15 wt% sodium hydroxide solution, the mass volume ratio of calcium boride powder and sodium hydroxide solution is 1 g: 20 mL, stir in a 70°C water bath for 4 h, filter out the solid product, dry it to obtain active calcium boride; then disperse the active calcium boride in ethanol, add γ-glycidyloxypropyltrimethoxysilane (KH-560), the mass volume ratio of active calcium boride, γ-glycidyloxypropyltrimethoxysilane and ethanol is 1 g: 0.25 g: 20 mL, reflux at 55°C for 8 h, filter out the solid product, and dry it to obtain epoxylated calcium boride;

[0048] S2. Tetrahydrofuran acrylate (THFA) and 4,6-diamino-2-mercaptopyrimidine (C4H6N4S) are sequentially added to N,N-dimethylformamide (DMF), the mass volume ratio of tetrahydrofuran acrylate, 4,6-diamino-2-mercaptopyrimidine and N,N-dimethylformamide is 0.39 g:0.33 g:15 mL. After being fully stirred until uniform, a photoinitiator BDK is added, and the amount added is 5% of the mass of 4,6-diamino-2-mercaptopyrimidine. The mixture is stirred for 1.5 h under ultraviolet conditions, the power of the ultraviolet lamp is 150 W, and the irradiation distance is 15 cm. After the treatment, the solvent is removed and dried to obtain a thioether compound;

[0049] S3. Mix the epoxylated calcium boride and the sulfide compound in anhydrous ethanol, add a few drops of triethylamine, the mass volume ratio of epoxylated calcium boride, sulfide compound, triethylamine and anhydrous ethanol is 1g:0.48g:0.005g:25mL, heat to 75°C, condense and reflux for 5h, remove the solvent after the treatment, dry and obtain a modified filler.

[0050] The preparation method of the coating for local spraying of carbon fiber composite materials comprises:

[0051] Step 1, firstly mix the epoxy modified acrylic resin, the modified filler, the dispersant and the solvent, and stir them thoroughly until they are uniform;

[0052] Step 2, adding defoamer and leveling agent to the mixed solution of step 1, and stirring again;

[0053] Step 3, adding a curing agent to the mixed solution of step 2, stirring evenly, to obtain a coating that can be applied and used.

[0054] Example 2

[0055] A coating for local spraying of carbon fiber composite materials, calculated by weight, comprising:

[0056] 56 parts of epoxy modified acrylic resin, 11 parts of modified filler, 0.2 parts of dispersant, 0.1 parts of defoamer, 0.1 parts of leveling agent, 18 parts of curing agent and 40 parts of solvent.

[0057] Wherein, the preparation method of epoxy modified acrylic resin comprises:

[0058] Epoxy resin E-20 and ethylene glycol butyl ether are mixed, heated to 80° C. under the protection of nitrogen, stirred until completely dissolved, and then a mixed solution of acrylic acid and half of the initiator is added dropwise, and the dropping time is controlled to be 2 hours. After the dropping is completed, the remaining half of the initiator is added dropwise, and the temperature is raised to 110° C., stirred for 2 hours, and cooled to room temperature to obtain epoxy modified acrylic resin; wherein the mass volume ratio of epoxy resin E-20, acrylic acid and ethylene glycol butyl ether is 1g:24g:40mL; the total amount of the initiator used is 1% of the total mass of acrylic acid, and the initiator is cumene hydroperoxide.

[0059] Among them, the dispersant is TEGO-760W; the defoamer is BYK-A530; the leveling agent is a silicone leveling agent, model HY-8110; the curing agent is an HDI trimer curing agent, brand Wanhua HT-600; and the solvent is ethyl acetate.

[0060] Wherein, the preparation method of the modified filler is:

[0061] S1. Mix calcium boride powder (CaB6, purity higher than 99%, particle size 10-20 μm) and 10 wt% sodium hydroxide solution, the mass volume ratio of calcium boride powder and sodium hydroxide solution is 1 g: 15 mL, stir in a 60°C water bath for 3 h, filter out the solid product, dry it to obtain active calcium boride; then disperse the active calcium boride in ethanol, add γ-glycidyloxypropyltrimethoxysilane (KH-560), the mass volume ratio of active calcium boride, γ-glycidyloxypropyltrimethoxysilane and ethanol is 1 g: 0.15 g: 15 mL, reflux at 50°C for 6 h, filter out the solid product, and dry it to obtain epoxylated calcium boride;

[0062] S2. Tetrahydrofuran acrylate (THFA) and 4,6-diamino-2-mercaptopyrimidine (C4H6N4S) are sequentially added to N,N-dimethylformamide (DMF), the mass volume ratio of tetrahydrofuran acrylate, 4,6-diamino-2-mercaptopyrimidine and N,N-dimethylformamide is 0.26g:0.22g:10mL. After being fully stirred until uniform, a photoinitiator BDK is added, and the amount added is 2% of the mass of 4,6-diamino-2-mercaptopyrimidine. The mixture is stirred for 1h under ultraviolet conditions, the power of the ultraviolet lamp is 100W, and the irradiation distance is 10cm. After the treatment, the solvent is removed and dried to obtain a thioether compound;

[0063] S3. Mix the epoxylated calcium boride and the sulfide compound in anhydrous ethanol, add a few drops of triethylamine, the mass volume ratio of epoxylated calcium boride, sulfide compound, triethylamine and anhydrous ethanol is 1g:0.37g:0.003g:20mL, heat to 70°C, condense and reflux for 4h, remove the solvent after the treatment, dry and obtain a modified filler.

[0064] The preparation method of the coating for local spraying of carbon fiber composite materials comprises:

[0065] Step 1, firstly mix the epoxy modified acrylic resin, the modified filler, the dispersant and the solvent, and stir them thoroughly until they are uniform;

[0066] Step 2, adding defoamer and leveling agent to the mixed solution of step 1, and stirring again;

[0067] Step 3, adding a curing agent to the mixed solution of step 2, stirring evenly, to obtain a coating that can be applied and used.

[0068] Example 3

[0069] A coating for local spraying of carbon fiber composite materials, calculated by weight, comprising:

[0070] 78 parts of epoxy modified acrylic resin, 22 parts of modified filler, 0.6 parts of dispersant, 0.5 parts of defoamer, 0.5 parts of leveling agent, 26 parts of curing agent and 60 parts of solvent.

[0071] Wherein, the preparation method of epoxy modified acrylic resin comprises:

[0072] Epoxy resin E-20 and ethylene glycol butyl ether are mixed, heated to 100° C. under the protection of nitrogen, stirred until completely dissolved, and then a mixed solution of acrylic acid and half of the initiator is added dropwise, and the dropping time is controlled to be 2-3 hours. After the dropping is completed, the remaining half of the initiator is added dropwise, and the temperature is raised to 120° C., stirred for 3 hours at this temperature, and cooled to room temperature to obtain epoxy modified acrylic resin; wherein the mass volume ratio of epoxy resin E-20, acrylic acid and ethylene glycol butyl ether is 3g:48g:60mL; the total amount of the initiator used is 5% of the total mass of acrylic acid, and the initiator is tert-butyl benzoyl peroxide.

[0073] Among them, the dispersant is TEGO-755W; the defoamer is BYK-1615; the leveling agent is a silicone leveling agent, model HY-1484; the curing agent is an HDI trimer curing agent, brand Tosoh HRX-90B; and the solvent is xylene.

[0074] Wherein, the preparation method of the modified filler is:

[0075] S1. Mix calcium boride powder (CaB6, purity higher than 99%, particle size 10-20 μm) and 20 wt% sodium hydroxide solution, the mass volume ratio of calcium boride powder and sodium hydroxide solution is 1 g: 25 mL, stir in a water bath at 80°C for 5 h, filter out the solid product, dry it to obtain active calcium boride; then disperse the active calcium boride in ethanol, add γ-glycidyloxypropyltrimethoxysilane (KH-560), the mass volume ratio of active calcium boride, γ-glycidyloxypropyltrimethoxysilane and ethanol is 1 g: (0.15-0.35) g: (15-25) mL, reflux at 50-60°C for 6-10 h, filter out the solid product, and dry it to obtain epoxylated calcium boride;

[0076] S2. Tetrahydrofuran acrylate (THFA) and 4,6-diamino-2-mercaptopyrimidine (C4H6N4S) are sequentially added to N,N-dimethylformamide (DMF), wherein the mass volume ratio of tetrahydrofuran acrylate, 4,6-diamino-2-mercaptopyrimidine and N,N-dimethylformamide is (0.26-0.52) g:(0.22-0.44) g:(10-20) mL. After being fully stirred until uniform, a photoinitiator BDK is added, wherein the amount added is 2%-8% of the mass of 4,6-diamino-2-mercaptopyrimidine, and the mixture is stirred for 1-2 h under ultraviolet conditions, the power of the ultraviolet lamp is 100-200 W, and the irradiation distance is 10-20 cm. After the treatment is completed, the solvent is removed and the mixture is dried to obtain a thioether compound.

[0077] S3. Mix the epoxylated calcium boride and the sulfide compound in anhydrous ethanol, add a few drops of triethylamine, the mass volume ratio of epoxylated calcium boride, sulfide compound, triethylamine and anhydrous ethanol is 1g:(0.37-0.59)g:(0.003-0.008)g:(20-30)mL, heat to 70-80°C, condense and reflux for 4-6h, remove the solvent after the treatment, dry and obtain a modified filler.

[0078] The preparation method of the coating for local spraying of carbon fiber composite materials comprises:

[0079] Step 1, firstly mix the epoxy modified acrylic resin, the modified filler, the dispersant and the solvent, and stir them thoroughly until they are uniform;

[0080] Step 2, adding defoamer and leveling agent to the mixed solution of step 1, and stirring again;

[0081] Step 3, adding a curing agent to the mixed solution of step 2, stirring evenly, to obtain a coating that can be applied and used.

[0082] Comparative Example 1

[0083] A coating for local spraying of carbon fiber composite materials, which differs from Example 1 in that the modified filler is replaced by calcium boride powder.

[0084] Comparative Example 2

[0085] A coating for local spraying of carbon fiber composite materials, which differs from Example 1 in that the modified filler is replaced by a mixture of calcium boride micropowder and tetrahydrofuran acrylate, and the mass ratio of the calcium boride micropowder to the tetrahydrofuran acrylate is 1:0.37.

[0086] Comparative Example 3

[0087] A coating for local spraying of carbon fiber composite materials, which differs from Example 1 in that the modified filler is replaced by a mixture of calcium boride micropowder and 4,6-diamino-2-mercaptopyrimidine, and the mass ratio of calcium boride micropowder to 4,6-diamino-2-mercaptopyrimidine is 1:0.37.

[0088] Experimental example

[0089] The coatings prepared in Examples 1-3 were applied: the surface of a carbon fiber plate (Shenzhen Albis Technology Co., Ltd.) was polished with #1000-2000 sandpaper, dust was blown off, and a coating with a thickness of 100 μm was sprayed, and then baked at 70±5°C for 45 minutes. The performance of the sprayed coating was tested, and the surface condition was observed with the naked eye based on the dried paint film. The impact resistance test was based on GB / T 1732-1993, the adhesion test was based on GB / T 9286-1998, the hardness test was based on GB / T6739-2006, and the weather resistance test was based on GB / T 1865-1997. The QUV-A method was used to test the gloss loss and color difference (△E) after 1000 hours of treatment.

[0090] The test results are shown in the following table:

[0091] Table 1 Performance test results of different coatings

[0092]

[0093] It can be seen from Table 1 above that when the coating prepared in Example 1 is used for carbon fiber board composite materials, the surface morphology is good, there is no orange peel, no exposed bottom, and the adhesion and hardness are high, the impact resistance is good, and it also has excellent weather resistance.

[0094] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0095] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A coating for local spraying of carbon fiber composite materials, characterized in that: Calculated by weight, including: 56-78 parts of epoxy modified acrylic resin, 11-22 parts of modified filler, 0.2-0.6 parts of dispersant, 0.1-0.5 parts of defoamer, 0.1-0.5 parts of leveling agent, 18-26 parts of curing agent and 40-60 parts of solvent.

2. The coating for local spraying of carbon fiber composite materials according to claim 1, characterized in that: The preparation method of the epoxy-modified acrylic resin comprises: Mix epoxy resin E-20 and ethylene glycol butyl ether, heat to 80-100°C under the protection of nitrogen, stir until completely dissolved, add a mixture of acrylic acid and half of the initiator dropwise, and control the dropping time to be 2-3h. After the dropping is completed, add the remaining half of the initiator, heat to 110-120°C, stir at this temperature for 2-3h, and cool to room temperature to obtain epoxy modified acrylic resin.

3. The coating for local spraying of carbon fiber composite materials according to claim 2, characterized in that: In the preparation process of the epoxy-modified acrylic resin, the mass volume ratio of epoxy resin E-20, acrylic acid and ethylene glycol butyl ether is (1-3) g: (24-48) g: (40-60) mL.

4. The coating for local spraying of carbon fiber composite materials according to claim 2, characterized in that: In the preparation process of the epoxy modified acrylic resin, the total amount of the initiator used is 1%-5% of the total mass of acrylic acid, and the initiator is one of benzoic acid peroxide, cumene hydroperoxide, and tert-butyl benzyl peroxide.

5. The coating for local spraying of carbon fiber composite materials according to claim 1, characterized in that: The dispersant is one of TEGO-670, TEGO-760W, and TEGO-755W; the defoamer is one of BYK-A525, BYK-A530, BYK-088, and BYK-1615; the leveling agent is an organic silicone leveling agent, and the model is one of HY-3510, HY-8110, HY-5057, and HY-1484.

6. The coating for local spraying of carbon fiber composite materials according to claim 1, characterized in that: The curing agent is an HDI trimer curing agent, and the brand is one of Wanhua HT-100, Wanhua HT-600, and Tosoh HRX-90B; the solvent is one of ethyl acetate, butyl acetate, toluene, and xylene.

7. The coating for local spraying of carbon fiber composite materials according to claim 1, characterized in that: The preparation method of the modified filler is: S1. Mix calcium boride powder and sodium hydroxide solution, stir in a water bath at 60-80°C for 3-5h, filter out the solid product, dry it to obtain active calcium boride; then disperse the active calcium boride in ethanol, add γ-glycidyloxypropyltrimethoxysilane (KH-560), reflux at 50-60°C for 6-10h, filter out the solid product, and dry it to obtain epoxylated calcium boride; S2, adding tetrahydrofuran acrylate (THFA) and 4,6-diamino-2-mercaptopyrimidine (C4H6N4S) to N,N-dimethylformamide (DMF) in sequence, stirring until uniform, adding a photoinitiator, stirring under ultraviolet conditions for 1-2 hours, after the treatment is completed, removing the solvent, and drying to obtain a thioether compound; S3. Mix the epoxylated calcium boride and the sulfide compound in anhydrous ethanol, add a few drops of triethylamine, raise the temperature to 70-80°C, condense and reflux for 4-6 hours, remove the solvent after the treatment, dry, and obtain a modified filler.

8. The coating for local spraying of carbon fiber composite materials according to claim 7, characterized in that: In S1, the mass volume ratio of calcium boride powder and sodium hydroxide solution is 1 g: (15-25) mL; the mass volume ratio of active calcium boride, γ-glycidyloxypropyltrimethoxysilane and ethanol is 1 g: (0.15-0.35) g: (15-25) mL.

9. The coating for local spraying of carbon fiber composite materials according to claim 7, characterized in that: In S2, the mass volume ratio of tetrahydrofuran acrylate, 4,6-diamino-2-mercaptopyrimidine and N,N-dimethylformamide is (0.26-0.52) g: (0.22-0.44) g: (10-20) mL.

10. The coating for local spraying of carbon fiber composite materials according to claim 7, characterized in that: In the S3, the mass volume ratio of epoxylated calcium boride, sulfide compound, triethylamine and anhydrous ethanol is 1 g: (0.37-0.59) g: (0.003-0.008) g: (20-30) mL.

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