A high-transparency matte varnish coating composition and its preparation method and application

Abstract

The present invention provides a high-transparency matte varnish coating composition that can be used for carbon fiber composite materials, including component A and component B, in parts by weight, component A includes 50-100 parts of self-matting resin, 0-30 parts of hydroxyl resin, 10-35 parts of a first solvent, 0.5-3 parts of an ultraviolet light absorber, 0.5-2 parts of a light stabilizer, and 0.1-3 parts of an additional auxiliary agent; component B includes: 40-90 parts of an isocyanate curing agent, and 10-60 parts of a second solvent; the weight ratio of component A to component B is any ratio between 1:10-20:1. The coating obtained by the coating composition provided by the present invention has the characteristics of high transparency, beautiful appearance, chemical corrosion resistance, scratch resistance, wear resistance and high weather resistance, and the carbon fiber composite material coated therewith can meet the application requirements of automotive exterior parts, etc. The present invention also relates to a preparation method of the above-mentioned high-transparency matte varnish coating composition and a surface treatment method based on the coating composition.

Description

Technical Field

[0001] The invention belongs to the field of surface coating of carbon fiber composite materials, and relates to a high-transparency matte varnish coating composition that can be used for carbon fiber composite materials, a preparation method thereof, and application thereof in surface treatment. Background Art

[0002] As a new type of low-density, high-strength, and high-rigidity material, carbon fiber composite material (CFRP) is becoming one of the most popular lightweight materials in the fields of automobiles, rail transit vehicles, sports equipment, etc. When it is used for the exterior finishes of rail transit, automobiles and other vehicles, in order to improve the appearance and protect the substrate, carbon fiber composite materials generally need to be painted. In order to present the special texture weaving effect of carbon fiber, most of the existing technologies use high-gloss varnish transparent coating to paint carbon fiber composite materials. With the expansion of the scope of application and the improvement of performance requirements, matte varnish transparent coating is more and more widely used in the coating of carbon fiber composite materials.

[0003] The current matte varnish generally uses fumed silica as a matting agent, and a large amount of fumed silica is required to achieve the desired matting effect. Although silica has good matting properties, it will affect the transparency of the varnish. When used in large amounts, the transparency of the varnish will be significantly reduced. Therefore, it is difficult for the current matte varnish coating to achieve high transparency and excellent matte effect at the same time. In addition, the transparent varnish coating on the surface of the carbon fiber composite material must be able to improve the good weather resistance of the substrate, so as to protect the carbon fiber composite material, especially the epoxy-based carbon fiber composite material, from yellowing.

[0004] In view of this, how to design a high-transparency matte varnish coating composition that can be used for surface coating of carbon fiber composite materials more efficiently and conveniently by spraying, so as to achieve excellent weather resistance, chemical corrosion resistance, scratch resistance and wear resistance while giving the carbon fiber composite materials a matte effect with visible fiber texture, thereby eliminating the above-mentioned defects and deficiencies in the prior art and better serving the needs of exterior paint surfaces of vehicles, etc., is a topic that needs to be urgently solved by relevant technical personnel in the industry. Summary of the invention

[0005] In order to overcome the above technical problems, the present invention provides a high-transparency matte varnish coating composition for carbon fiber composite materials, a preparation method thereof, and an application thereof in surface treatment. The coating composition can play a good decorative and protective role on the surface of the carbon fiber composite material, so that the carbon fiber composite material has a matte effect with visible fiber texture. At the same time, the coating composition has the characteristics of low-temperature rapid curing, high weather resistance, chemical corrosion resistance, scratch resistance and wear resistance, and the carbon fiber composite material coated with the coating can meet the application requirements of automotive exterior parts.

[0006] In a first aspect of the present invention, there is provided a high-transparency matte varnish coating composition for carbon fiber composite materials, comprising component A and component B, in parts by weight:

[0007] Component A comprises: 50-100 parts of self-matting resin, 0-30 parts of hydroxy resin, 10-35 parts of first solvent, 0.5-3 parts of ultraviolet light absorber, 0.5-2 parts of light stabilizer, and 0.1-3 parts of additional auxiliary agent;

[0008] Component B includes: 40-90 parts of isocyanate curing agent and 10-60 parts of second solvent; wherein the weight ratio of component A to component B is any ratio between 1:10-20:1.

[0009] Preferably, the component A comprises: 60-80 parts of self-matting resin, 0-20 parts of hydroxyl resin, 15-35 parts of first solvent, 0.5-3 parts of ultraviolet light absorber, 0.5-2 parts of light stabilizer, and 0.1-3 parts of additional additives;

[0010] More preferably, the weight ratio of component A to component B is any ratio between 1:5 and 15:1.

[0011] Self-matting resin

[0012] In some embodiments of the present invention, the self-matting resin is an acrylic copolymer having a core-shell structure due to a solubility difference. In the coating composition, the gloss of the coating decreases as the content of the self-matting resin increases.

[0013] Preferably, the self-matting resin includes but is not limited to Hypomer MT-2550K, Hypomer MT-2550F, Hypomer MT-2350 and the like commercially available from Elementis.

[0014] Hydroxyl resin

[0015] In some embodiments of the present invention, the hydroxy resin is selected from at least one of the group consisting of hydroxyl-containing acrylic resin, hydroxyl-containing polyester resin, hydroxyl-containing polyether resin, and hydroxyl-containing silicone resin. In the coating composition, the gloss of the coating increases with the increase of the hydroxyl resin content.

[0016] Further, the hydroxyl-containing acrylic resin is polymerized from acrylic acid monomers, methacrylic acid monomers and derivatives thereof. Preferably, the hydroxyl-containing acrylic resin includes but is not limited to Setalux 1907BA-75, TIRES 2850, SETALUX 1774 SS-65, SETALUX 1215 BA-68, SETALUX 1274BA-70, SETALUX 91757 VX-60, SETALUX 91795 VX-60, SETALUX 61767 VX-60, etc. commercially available from Allnex, or Joncryl 507, Joncryl 804, Joncryl 910, etc. commercially available from BASF.

[0017] Further, the hydroxyl-containing polyester resin includes but is not limited to conventional saturated polyester polyols, polycaprolactone polyols and polycarbonate diols. Preferably, the hydroxyl-containing polyester resin includes but is not limited to SETAL 1612 VS-60, SETAL 1715 VX-74, SETAL 90173 SS-50, SETAL 1603 BA-78, SETAL 168 SS-80, SETAL 82166 SS-64, etc., commercially available from Allnex, or K-FlexXM-332, K-Flex 148, K-Flex XM-337, etc., commercially available from King Industries.

[0018] Furthermore, the hydroxyl-containing polyether resin includes but is not limited to Sovermol 750, Sovermol 805, Sovermol 819 and the like commercially available from BASF.

[0019] Isocyanate curing agent

[0020] In some embodiments of the present invention, the isocyanate curing agent includes but is not limited to one or more of aliphatic isocyanate monomers, aliphatic isocyanate polymers, alicyclic isocyanate monomers, alicyclic isocyanate polymers, aromatic isocyanate monomers, aromatic isocyanate polymers, isocyanate hybrids, and isocyanate hybrid polymers.

[0021] Furthermore, the aliphatic isocyanate monomer includes, but is not limited to, one or more of tetramethylene 1,4-diisocyanate, hexamethylene 1,6-diisocyanate, 2,2,4-trimethylhexane 1,6-diisocyanate, ethylene diisocyanate, and 1,12-dodecane diisocyanate.

[0022] Furthermore, the aliphatic isocyanate polymer is an aliphatic isocyanate dimer or an aliphatic isocyanate trimer.

[0023] Furthermore, the alicyclic isocyanate monomer includes but is not limited to one or more of isophorone diisocyanate, cyclobutane 1,3-diisocyanate, cyclohexane 1,3-diisocyanate, cyclohexane 1,4-diisocyanate, methylcyclohexyl diisocyanate, 4,4'-methylene dicyclohexyl diisocyanate, and hydrogenated diphenylmethane diisocyanate.

[0024] Furthermore, the alicyclic isocyanate polymer is an alicyclic isocyanate dimer or an alicyclic isocyanate trimer.

[0025] Furthermore, the aromatic isocyanate monomer includes but is not limited to one or more of toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, diphenylmethane 4,4'-diisocyanate, diphenylmethane 2,4'-diisocyanate, p-phenylene diisocyanate, biphenyl diisocyanate, 3,3'-dimethyl-4,4'-diphenylene diisocyanate, and hexahydrophenylene 1,3-diisocyanate.

[0026] Furthermore, the aromatic isocyanate polymer is an aromatic isocyanate dimer or an aromatic isocyanate trimer.

[0027] Furthermore, the isocyanate hybrid polymer is an isocyanate hybrid dimer or an isocyanate hybrid trimer.

[0028] More specifically, the isocyanate curing agent can be any commercially available isocyanate curing agent that meets the above description, including but not limited to Desmodur N 3300, Desmodur N 3390, Desmodur N 3600, Desmodur N 3900 and Desmodur Z 4470 commercially available from Bayer MaterialScience, or HDT-90, HDT-100 and HDT-LV commercially available from Rhodia Group, or Basonat HI100 commercially available from BASF.

[0029] Solvents

[0030] The first solvent and the second solvent may be the same or different, including but not limited to hexane, heptane, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, butyl acetate, ethyl acetate, 3-ethoxypropionic acid ethyl ester, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, ethylene glycol ethyl ether acetate, propylene carbonate, dimethyl carbonate, No. 100 solvent oil, No. 150 solvent oil, No. 200 solvent oil, etc.

[0031] UV absorber

[0032] In some embodiments of the present invention, the ultraviolet light absorber is selected from one or more of Tinuvin 328, Tinuvin 384-2, Tinuvin 900, Tinuvin 928, Tinuvin 1130, Tinuvin 400, Tinuvin 479, Tinuvin 477, and Tinuvin CarboProtect.

[0033] Light Stabilizer

[0034] In one embodiment of the present invention, the light stabilizer is selected from one or more of Tinuvin 144, Tinuvin 123, Tinuvin 292, Tinuvin 440 and Tinuvin 622, including but not limited to.

[0035] Additional additives

[0036] In some embodiments of the present invention, the additional additive in component A is selected from one or more of a drying agent, a substrate wetting agent, a wetting and dispersing agent, a leveling agent, and a rheological additive. It should be understood by those skilled in the art that the additive can be selected according to actual process requirements, and the scope of the present invention is not limited to the additives listed above.

[0037] The second aspect of the present invention provides a method for preparing the high-transparency matte varnish coating composition according to the first aspect of the present invention, comprising the steps of:

[0038] (1) preparing component A: providing 50-100 parts of a self-matting resin, 0-30 parts of a hydroxyl resin, 0.5-3 parts of an ultraviolet light absorber, 0.5-2 parts of a light stabilizer, and 0.1-3 parts of an additional auxiliary agent; and providing 10-35 parts of a first solvent, adding the above components under stirring, and stirring until the mixture is uniformly mixed to obtain the component A;

[0039] (2) preparing component B: providing 40-90 parts of an isocyanate curing agent and 10-60 parts of a second solvent, flushing an inert gas into the second solvent, and adding each component under stirring, stirring until the mixture is uniformly mixed, thereby obtaining component B;

[0040] The component A and the component B are fully mixed in any weight ratio between 1:10 and 20:1 to obtain the high-transparency matte varnish coating composition.

[0041] The high-transparency matte varnish coating composition has a viscosity at 23° C. ranging from 100 to 20,000 mPa·s, preferably ranging from 100 to 10,000 mPa·s, and more preferably ranging from 100 to 5,000 mPa·s.

[0042] The third aspect of the present invention provides a surface treatment method, which comprises coating at least one layer of the high-transparency matte varnish coating composition described in the first aspect of the present invention on at least one surface of the carbon fiber composite material.

[0043] In some embodiments of the present invention, the coating method includes but is not limited to air spraying, airless spraying, online electrostatic spraying or in-mold coating.

[0044] Beneficial effects of the present invention

[0045] Compared with the prior art, the technical solution provided by the present invention has the following advantages:

[0046] (1) The high-transparency matte varnish coating composition of the present invention can give the carbon fiber composite material a high-transparency and beautiful matte varnish effect, and the carbon fiber texture of the composite material is clearly visible.

[0047] (2) The high-transparency matte varnish coating composition of the present invention has good weather resistance, and can provide good protection for the surface of carbon fiber composite materials after adding ultraviolet light absorbers and light stabilizers.

[0048] (3) The high-transparency matte varnish coating composition of the present invention has the characteristics of low-temperature rapid curing, chemical corrosion resistance, scratch resistance and wear resistance, and can meet the application requirements of carbon fiber composite material automotive exterior parts. DETAILED DESCRIPTION

[0049] The specific embodiments of the present invention are described in detail below. It will be appreciated by those skilled in the art that the present invention is not limited to the embodiments described below, and the technical concept of the present invention can be implemented in combination with other known technologies or other technologies having the same functions as those known technologies.

[0050] In the description of the following specific embodiments, in order to clearly demonstrate the structure and working mode of the present invention, many directional words will be used for description, but the words "front", "rear", "left", "right", "outside", "inside", "outward", "inward", "axial", "radial" and the like should be understood as convenient terms and should not be understood as restrictive terms.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise clearly specified, "plurality" means two or more.

[0052] Unless otherwise stated, each aspect or embodiment defined herein may be combined with any other aspect or embodiments. In particular, any preferred or advantageous feature may be combined with any other preferred or advantageous feature.

[0053] The specific embodiments of the present invention are described in detail below.

[0054] Example 1

[0055] In this embodiment, a high-transparency matte varnish coating composition 1 is provided, and the high-transparency matte varnish coating composition 1 comprises component A and component B. In parts by weight, the compositions of component A and component B are as follows:

[0056] Table 1.1 Composition of component A in Example 1

[0057] Components name Number of copies Self-matting resin Hypomer MT-2550K 60 Hydroxyl resin SETAL 1603 BA-78 10 First solvent 1 Butyl acetate 18 First solvent 2 Propylene glycol methyl ether acetate 10 Additional additives 1 Substrate wetting agent 0.3 Additional additives 2 Leveling agent 0.2 UV absorber 1 Light Stabilizer 0.5

[0058] Table 1.2 Composition of component B in Example 1

[0059]

[0060]

[0061] The specific steps of the preparation method and application of the high-transparency matte varnish coating composition 1 are as follows:

[0062] (1) Under stirring, add SETALUX 1215 BA-78, Hypomer MT-2550K, butyl acetate and propylene glycol methyl ether acetate in sequence to the main container, stir for 15-20 minutes, and control the stirring rate at 500-1500 rpm to make them evenly mixed. Then, add the substrate wetting agent, leveling agent, ultraviolet light absorber and light stabilizer, and continue stirring for 20-30 minutes to obtain component A. The viscosity range of component A at 23°C is 100-20000 mPa·s.

[0063] (2) Nitrogen is injected into the composite solvent of butyl acetate and propylene glycol methyl ether acetate, and isocyanate curing agent Desmodur N 3390 is added under stirring, and stirred for 10-20 minutes to obtain component B. The mass percentage of the isocyanate curing agent in component B is 60-90%.

[0064] (3) When in use, component A and component B are fully mixed in a weight ratio of 5:1 to 15:1 to obtain the coating composition 1.

[0065] (4) The coating composition 1 was applied to the epoxy-based carbon fiber composite material substrate coated with a transparent primer, and cured at 80 degrees Celsius for 60 minutes, and then the performance test was carried out. The relevant results are shown in Table 6.

[0066] Example 2

[0067] In this embodiment, a high-transparency matte varnish coating composition 2 is provided, and the high-transparency matte varnish coating composition 2 includes component A and component B. In parts by weight, the compositions of component A and component B are as follows:

[0068] Table 2.1 Composition of component A in Example 2

[0069] Components name Number of copies Self-matting resin Hypomer MT-2550F 60 Hydroxyl resin SETAL 1603 BA-78 10 First solvent 1 Butyl acetate 18 First solvent 2 Propylene glycol methyl ether acetate 10 Additional additives 1 Substrate wetting agent 0.3 Additional additives 2 Leveling agent 0.2 UV absorber 1 Light Stabilizer 0.5

[0070] Table 2.2 Composition of component B in Example 2

[0071] Components name Number of copies Isocyanate curing agent Desmodur N 3390 70 Second solvent 1 Butyl acetate 15 Second solvent 2 Propylene glycol methyl ether acetate 15

[0072] The specific steps of the preparation method of the high-transparency matte varnish coating composition 2 are as follows:

[0073] (1) Under stirring, add SETALUX 1215 BA-78, Hypomer MT-2550F, butyl acetate and propylene glycol methyl ether acetate in sequence to the main container, stir for 15-20 minutes, and control the stirring rate at 500-1500 rpm to make them evenly mixed. Then, add the substrate wetting agent, leveling agent, ultraviolet light absorber and light stabilizer, and continue stirring for 20-30 minutes to obtain component A. The viscosity range of component A at 23°C is 100-20000 mPa·s.

[0074] (2) Nitrogen is injected into the composite solvent of butyl acetate and propylene glycol methyl ether acetate, and isocyanate curing agent Desmodur N 3390 is added under stirring, and stirred for 10-20 minutes to obtain component B. The mass percentage of the isocyanate curing agent in component B is 60-90%.

[0075] (3) When in use, component A and component B are fully mixed in a weight ratio of 5:1 to 15:1 to obtain the coating composition 2.

[0076] (4) The coating composition 2 was applied to the epoxy-based carbon fiber composite material substrate coated with a transparent primer, and cured at 80 degrees Celsius for 60 minutes, and then the performance test was carried out. The relevant results are shown in Table 6.

[0077] Example 3

[0078] In this embodiment, a high-transparency matte varnish coating composition 3 is provided, and the high-transparency matte varnish coating composition 3 includes component A and component B. In parts by weight, the compositions of component A and component B are as follows:

[0079] Table 2.1 Composition of component A in Example 3

[0080] Components name Number of copies Self-matting resin Hypomer MT-2550F 65 Hydroxyl resin SETAL 1603 BA-78 5 First solvent 1 Butyl acetate 18 First solvent 2 Propylene glycol methyl ether acetate 10 Additional additives 1 Substrate wetting agent 0.3 Additional additives 2 Leveling agent 0.2 UV absorber 1 Light Stabilizer 0.5

[0081] Table 2.2 Composition of component B in Example 3

[0082] Components name Number of copies Isocyanate curing agent Desmodur N 3390 70 Second solvent 1 Butyl acetate 15 Second solvent 2 Propylene glycol methyl ether acetate 15

[0083] The specific steps of the preparation method of the high-transparency matte varnish coating composition 3 are as follows:

[0084] (1) Under stirring, add SETALUX 1215 BA-78, Hypomer MT-2550F, butyl acetate and propylene glycol methyl ether acetate in sequence to the main container, stir for 15-20 minutes, and control the stirring rate at 500-1500 rpm to make them evenly mixed. Then, add the substrate wetting agent, leveling agent, ultraviolet light absorber and light stabilizer, and continue stirring for 20-30 minutes to obtain component A. The viscosity range of component A at 23°C is 100-20000 mPa·s.

[0085] (2) Nitrogen is injected into the composite solvent of butyl acetate and propylene glycol methyl ether acetate, and isocyanate curing agent Desmodur N 3390 is added under stirring, and stirred for 10-20 minutes to obtain component B. The mass percentage of the isocyanate curing agent in component B is 60-90%.

[0086] (3) When in use, component A and component B are fully mixed in a weight ratio of 5:1 to 15:1 to obtain the coating composition 2.

[0087] (4) The coating composition 3 was applied to the epoxy-based carbon fiber composite material substrate coated with a transparent primer, and cured at 80 degrees Celsius for 60 minutes, and then the performance test was carried out. The relevant results are shown in Table 6.

[0088] Example 4

[0089] In this embodiment, a high-transparency matte varnish coating composition 4 is provided, and the high-transparency matte varnish coating composition 4 comprises component A and component B. In parts by weight, the compositions of component A and component B are as follows:

[0090] Table 3.1 Composition of component A in Example 4

[0091] Components name Number of copies Self-matting resin Hypomer MT-2550F 70 First solvent 1 Butyl acetate 18 First solvent 2 Propylene glycol methyl ether acetate 10 Additional additives 1 Substrate wetting agent 0.3 Additional additives 2 Leveling agent 0.2 UV absorber 1 Light Stabilizer 0.5

[0092] Table 3.2 Composition of component B in Example 4

[0093] Components name Number of copies Isocyanate curing agent Desmodur N 3390 70 Second solvent 1 Butyl acetate 15 Second solvent 2 Propylene glycol methyl ether acetate 15

[0094] The specific steps of the preparation method of the high-transparency matte varnish coating composition 4 are as follows:

[0095] (1) Under stirring, add Hypomer MT-2550F, butyl acetate and propylene glycol methyl ether acetate in sequence to the main container, stir for 15-20 minutes, and control the stirring rate at 500-1500 rpm to make them evenly mixed. Then, add the substrate wetting agent, leveling agent, ultraviolet light absorber and light stabilizer, and continue stirring for 20-30 minutes to obtain component A. The viscosity range of component A at 23°C is 100-20000 mPa·s.

[0096] (2) Nitrogen is injected into the composite solvent of butyl acetate and propylene glycol methyl ether acetate, and isocyanate curing agent Desmodur N 3390 is added under stirring, and stirred for 10-20 minutes to obtain component B. The mass percentage of the isocyanate curing agent in component B is 60-90%.

[0097] (3) When in use, component A and component B are fully mixed in a weight ratio of 5:1 to 15:1 to obtain the coating composition 3.

[0098] (4) The coating composition 4 was applied to the epoxy-based carbon fiber composite material substrate coated with a transparent primer, and cured at 80 degrees Celsius for 60 minutes, and then the performance test was carried out. The relevant results are shown in Table 6.

[0099] Comparative Example 1

[0100] In this comparative example 1, a colorless transparent coating composition 5 is provided, and the colorless transparent coating composition 5 comprises component A and component B. In parts by weight, the compositions of component A and component B are as follows:

[0101] Table 4.1 Composition of component A in comparative example 1

[0102] Components name Number of copies Hydroxyl resin SETALUX 1774 SS-65 60 Fumed silica matting powder ACEMATT OK520 10 First solvent 1 Butyl acetate 18 First solvent 2 Propylene glycol methyl ether acetate 10 Additional additives 1 Substrate wetting agent 0.3 Additional additives 2 Leveling agent 0.2 UV absorber 1 Light Stabilizer 0.5

[0103] Table 4.2 Composition of component B in comparative example 1

[0104] Components name Number of copies Isocyanate curing agent Desmodur N 3390 70 Second solvent 1 Butyl acetate 15 Second solvent 2 Propylene glycol methyl ether acetate 15

[0105] It should be noted that: in this example, component A contains only hydroxyl resin and no self-matting resin, and its matte effect is mainly achieved by adding fumed silica matting powder, which is not within the scope of the present invention. Therefore, this example is comparative example 1.

[0106] The specific steps of the preparation method of the colorless transparent coating composition 5 are as follows:

[0107] (1) Under stirring, add SETALUX 1774 SS-65, butyl acetate and propylene glycol methyl ether acetate to the main container in sequence, stir for 15-20 minutes, and control the stirring rate at 500-1500 rpm. After mixing evenly, add ACEMATT OK520 fumed silica matting powder, stir for 15-20 minutes, and control the stirring rate at 500-1500 rpm. After mixing evenly, add substrate wetting agent, leveling agent, ultraviolet light absorber and light stabilizer, and continue stirring for 20-30 minutes to obtain component A. The viscosity range of component A at 23°C is 100-20000 mPa·s.

[0108] (2) Nitrogen is injected into the composite solvent of butyl acetate and propylene glycol methyl ether acetate, and isocyanate curing agent Desmodur N 3390 is added under stirring, and stirred for 10-20 minutes to obtain component B. The mass percentage of the isocyanate curing agent in component B is 60-90%.

[0109] (3) When in use, component A and component B are fully mixed in a weight ratio of 1:5-15:1 to obtain the coating composition 4.

[0110] (4) The coating composition 5 was applied to the epoxy-based carbon fiber composite material substrate coated with a transparent primer, and cured at 80 degrees Celsius for 60 minutes, and then the performance test was carried out. The relevant results are shown in Table 6.

[0111] Comparative Example 2

[0112] In this comparative example 2, a colorless low-transparency matte coating composition 6 is provided, wherein the colorless low-transparency matte composition 6 comprises component A and component B, wherein, by weight, the compositions of component A and component B are as follows:

[0113] Table 5.1 Composition of component A in comparative example 2

[0114] Components name Number of copies Hydroxyl resin SETALUX 1774 SS-65 55 Fumed silica matting powder ACEMATT OK520 15 First solvent 1 Butyl acetate 18 First solvent 2 Propylene glycol methyl ether acetate 10 Additional additives 1 Substrate wetting agent 0.3 Additional additives 2 Leveling agent 0.2 UV absorber 1 Light Stabilizer 0.5

[0115] Table 5.2 Composition of component B in comparative example 2

[0116] Components name Number of copies Isocyanate curing agent Desmodur N 3390 70 Second solvent 1 Butyl acetate 15 Second solvent 2 Propylene glycol methyl ether acetate 15

[0117] It should be noted that: in this example, component A contains only hydroxyl resin and no self-matting resin, and its matte effect is mainly achieved by adding fumed silica matting powder, which is not within the scope of the present invention. Therefore, this example is comparative example 2.

[0118] The specific steps of the preparation method of the colorless low-transparency matte coating composition 5 are as follows:

[0119] (1) Under stirring, add SETALUX 1774 SS-65, butyl acetate and propylene glycol methyl ether acetate to the main container in sequence, stir for 15-20 minutes, and control the stirring rate at 500-1500 rpm. After mixing evenly, add ACEMATT OK520 fumed silica matting powder, stir for 15-20 minutes, and control the stirring rate at 500-1500 rpm. After mixing evenly, add substrate wetting agent, leveling agent, ultraviolet light absorber and light stabilizer, and continue stirring for 20-30 minutes to obtain component A. The viscosity range of component A at 23°C is 100-20000 mPa·s.

[0120] (2) Nitrogen is injected into the composite solvent of butyl acetate and propylene glycol methyl ether acetate, and isocyanate curing agent Desmodur N 3390 is added under stirring, and stirred for 10-20 minutes to obtain component B. The mass percentage of the isocyanate curing agent in component B is 60-90%.

[0121] (3) When in use, component A and component B are fully mixed in a weight ratio of 1:5-15:1 to obtain the coating composition 5.

[0122] (4) The coating composition 6 was applied to the epoxy-based carbon fiber composite material substrate coated with a transparent primer, and cured at 80 degrees Celsius for 60 minutes, and then the performance test was carried out. The relevant results are shown in Table 6.

[0123] Comparison results

[0124] In this example, the high-transparency matte varnish coating composition 1 of Example 1, the high-transparency matte varnish coating composition 2 of Example 2, the high-transparency matte varnish coating composition 3 of Example 3, the high-transparency matte varnish coating composition 4 of Example 4, the colorless transparent coating composition 5 of Comparative Example 1, and the colored opaque coating composition 6 of Comparative Example 2 are compared.

[0125] Specifically, Example 1 is a carbon fiber composite material sample (already coated with a transparent primer) coated with a high-transparency matte varnish coating composition 1;

[0126] Example 2 is a carbon fiber composite material sample (already coated with a transparent primer) coated with a high-transparency matte varnish coating composition 2;

[0127] Example 3 is a carbon fiber composite material sample (already coated with a transparent primer) coated with a high-transparency matte varnish coating composition 3;

[0128] Example 4 is a carbon fiber composite material sample (already coated with a transparent primer) coated with a high-transparency matte varnish coating composition 4;

[0129] Comparative Example 1 is a carbon fiber composite material sample (already coated with a transparent primer) coated with 5 coating layers of the colorless transparent coating composition;

[0130] Comparative Example 2 is a carbon fiber composite material sample (already coated with a transparent primer) coated with 6 layers of a colorless low-transparency coating composition;

[0131] The performance test results of each sample are shown in Table 6.

[0132]

[0133] Table 6 Performance test results of each coating composition on carbon fiber composite material samples

[0134] Wherein, the light transmittance is in accordance with GB / T 2410-2008 "Determination of light transmittance and haze of transparent plastics". The transparency of the coating can be expressed by directly measuring the light transmittance of the coating in the visible light wavelength range (wavelength of 400nm-700nm) using an ultraviolet visible spectrophotometer (U-4100, manufactured by Hitachi Instruments, Japan), or indirectly testing the light transmittance of the coating in the visible light wavelength range (wavelength of 400nm-700nm) by using a colorless transparent glass plate as a substrate to prepare the coating. Here, the applicant uses a colorless transparent glass plate as a substrate to prepare the above coatings (Example 1, Example 2, Example 3, Example 4, Comparative Example 1, Comparative Example 2) of the same film thickness to compare the transparency of the above coatings. For matte varnish, a transmittance of ≥80% at a wavelength of 400nm-700nm indicates that the coating has good transparency, while the lower the transmittance at a wavelength of 400nm-700nm, the worse the transparency of the coating, which can easily cover the color and texture under the coating. Especially when used for coating applications on the surface of carbon fiber composite materials, the fiber texture will be unclear.

[0135] The results in Table 6 show that in terms of visual fiber texture effect, appearance fineness, light transmittance, gasoline resistance and xenon light aging performance, Examples 1-4 performed better than Comparative Examples 1-2. At the same time, matte varnish effects of different glosses can be achieved by adjusting the ratio of high gloss resin (i.e., hydroxyl resin) and self-matting resin.

[0136] The light transmittances of Comparative Examples 1 and 2 were 70.4% and 65.5%, respectively, which were significantly lower than those of Examples 1-4, and the visual fiber texture effect was relatively poor. In addition, in terms of appearance fineness, gasoline resistance, and xenon light aging resistance, Comparative Examples 1 and 2 using matting powder were also inferior to the coating composition using the self-matting resin system to a certain extent.

[0137] Unless otherwise specified, qualifiers such as "first" and "second" appearing in this document do not refer to limitations on time sequence, quantity, or importance, but are only used to distinguish one technical feature from another technical feature in this technical solution. Similarly, modifiers such as "about" and "approximately" appearing before a numeral in this document usually include the number itself, and their specific meanings should be understood in conjunction with the context.

[0138] The present invention is described in this specification only in more preferred specific embodiments, the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the present invention. Any technical solutions that can be obtained by those skilled in the art through logical analysis, reasoning or limited experiments according to the concept of the present invention should be within the protection scope of the present invention.

Claims

1. A high transparency matte varnish coating composition for carbon fiber composite materials, characterized in that: The high-transparency matte varnish coating composition comprises component A and component B, in parts by weight: Component A comprises: 50-100 parts of self-matting resin, 0-30 parts of hydroxy resin, 10-35 parts of first solvent, 0.5-3 parts of ultraviolet light absorber, 0.5-2 parts of light stabilizer, and 0.1-3 parts of additional auxiliary agent; Component B includes: 40-90 parts of an isocyanate curing agent, and 10-60 parts of a second solvent; The weight ratio of component A to component B is any ratio between 1:10 and 20:

1.

2. The high-transparency matte varnish coating composition according to claim 1, characterized in that: The self-matting resin is an acrylic copolymer having a core-shell structure, and the core-shell structure is formed by a solubility difference.

3. The high-transparency matte varnish coating composition according to claim 1, characterized in that: The hydroxy resin is selected from one or more of hydroxyl-containing acrylic resin, hydroxyl-containing polyester resin, hydroxyl-containing polyether resin, and hydroxyl-containing silicone resin; Preferably, the hydroxyl-containing acrylic resin is polymerized from acrylic acid monomers, methacrylic acid monomers and derivatives thereof; and the hydroxyl-containing polyester resin is selected from one or more of saturated polyester polyols, polycaprolactone polyols and polycarbonate diols.

4. The high-transparency matte varnish coating composition according to claim 1, characterized in that: The isocyanate curing agent is selected from one or more of aliphatic isocyanate monomers, aliphatic isocyanate polymers, alicyclic isocyanate monomers, alicyclic isocyanate polymers, aromatic isocyanate monomers, aromatic isocyanate polymers, isocyanate hybrids, and isocyanate hybrid polymers; Preferably, the aliphatic isocyanate monomer is selected from one or more of tetramethylene 1,4-diisocyanate, hexamethylene 1,6-diisocyanate, 2,2,4-trimethylhexane 1,6-diisocyanate, ethylene diisocyanate, and 1,12-dodecane diisocyanate; the aliphatic isocyanate polymer is an aliphatic isocyanate dimer or an aliphatic isocyanate trimer; the alicyclic isocyanate monomer is selected from isophorone diisocyanate, cyclobutane 1,3-diisocyanate, cyclohexane 1,3-diisocyanate, cyclohexane 1,4-diisocyanate, methylcyclohexyl diisocyanate, The aromatic isocyanate monomer is selected from one or more of toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, diphenylmethane 4,4'-diisocyanate, diphenylmethane 2,4'-diisocyanate, p-phenylene diisocyanate, biphenyl diisocyanate, 3,3'-dimethyl-4,4'-diphenylene diisocyanate, hexahydrophenylene 1,3-diisocyanate.

5. The high-transparency matte varnish coating composition according to claim 1, characterized in that: The first solvent in component A of the coating composition and the second solvent in component B are independently selected from one or more of hexane, heptane, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, butyl acetate, ethyl acetate, 3-ethoxypropionic acid ethyl ester, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, ethylene glycol ethyl ether acetate, propylene carbonate, dimethyl carbonate, No. 100 solvent oil, No. 150 solvent oil, and No. 200 solvent oil.

6. The high-transparency matte varnish coating composition according to claim 1, characterized in that: The additional additive in component A is selected from one or more of a drying agent, a substrate wetting agent, a wetting and dispersing agent, a leveling agent, and a rheological additive.

7. A method for preparing the high-transparency matte varnish coating composition according to any one of claims 1 to 6, comprising the steps of: (1) preparing component A: providing 50-100 parts of a self-matting resin, 0-30 parts of a hydroxyl resin, 0.5-3 parts of an ultraviolet light absorber, 0.5-2 parts of a light stabilizer, and 0.1-3 parts of an additional auxiliary agent; and providing 10-35 parts of a first solvent, adding the above components under stirring, and stirring until the mixture is uniformly mixed to obtain the component A; (2) preparing component B: providing 40-90 parts of an isocyanate curing agent; and providing 10-60 parts of a second solvent, injecting an inert gas into the second solvent, and adding each component under stirring, stirring until the mixture is uniform, thereby obtaining component B; (3) fully mixing component A and component B in a weight ratio of 1:10 to 20:1 to obtain the high-transparency matte varnish coating composition; Preferably, the prepared coating composition meets the following conditions: the viscosity range at 23°C is 100 to 20000 mPa·s; more preferably, the following conditions are met: the viscosity range at 23°C is 100-10000 mPa·s; further preferably, the following conditions are met: the viscosity range at 23°C is 100-5000 mPa·s.

8. A surface treatment method, characterized in that The treatment method comprises coating at least one layer of the high-transparency matte varnish coating composition according to any one of claims 1 to 6 on at least one surface of the carbon fiber composite material.

9. The surface treatment method according to claim 8, characterized in that The coating method includes air spraying, airless spraying, online electrostatic spraying or in-mold coating.

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