WO2020063004A1

WO2020063004A1 - Method for surface treatment of composite materials, and coating composition and preparation method therefor

Info

Publication number: WO2020063004A1
Application number: PCT/CN2019/094353
Authority: WO
Inventors: Lichao LIU; Deheng LI; Hongxia PAN; Jiaxi XU; Xuechun REN; Xuesan WANG; Leilei RUI; Xudong Jia; Junfeng Guo
Original assignee: Nippon Paint (China) Co., Ltd
Priority date: 2018-09-28
Filing date: 2019-07-02
Publication date: 2020-04-02
Also published as: CN110964422A

Abstract

A method for surface treatment of a composite material and a coating composition are provided. The coating composition comprises at least a polyamine resin and at least a curing agent having an isocyanate group. The polyamine resin has at least two or more amino groups selected from one or more of a primary amino group and a secondary amino group.

Description

METHOD FOR SURFACE TREATMENT OF COMPOSITE MATERIALS, AND COATING COMPOSITION AND PREPARATION METHOD THEREFOR

BACKGROUND Technical Field

The present application relates to the technical field of surface painting of composite materials, and particularly to a coating composition for surface pretreatment of composite materials, especially fiber reinforced composite materials, and preparation method and use of the coating composition on the surface of composite materials.

Related Art

At present, in order to reduce the energy consumption of fuel-engined vehicles and improve the cruising range of electric vehicles, automobile lightweighting has become an inevitable trend in the future development of the automotive industry. The development of lightweight vehicles promotes the use of magnesium/aluminum alloys, engineering plastics and fiber reinforced composite materials in the automotive industry. Among them, the fiber reinforced composite material has the advantages of light weight, easy forming, strong rigidity, high degree of freedom in shape design, corrosion resistance, stable size and performance, and being readily sprayable. These have created favorable conditions for the use of fiber reinforced composite materials in the automotive industry.

However, due to the mismatch in the coefficient of thermal expansion between the fiber reinforcer and the resin matrix in the fiber reinforced composite material, as shown in Fig. 1, clearly visible fiber textures 2 are produced on the surface of the composite material during the preparation of the fiber reinforced composite material 1, and will still appear on the surface of a paint film after the paint film is painted and cured. This phenomenon is called the fiber replication effect.

This fiber replication effect can cause anisotropy in the surface of the fiber reinforced composite material, which makes it difficult for the fiber reinforced composite material to meet the high appearance requirements for use in components with Class A surface. For the definition of Class A surface, M. NEITZEL ("Surface Quality Characterization of Textile-Reinforced Thermoplastics" , POLYMER COMPOSITES, August, 2000, Vol. 21, Page 631) , and N. Boyard ("A Physical Approach to Define a Class A Surface in Polymer Thermosetting Composite Materials" , Journal of Applied Polymer Science, 2007, Vol. 103, Page 452) give the following description of Class A surface: A composite material has a class A surface if its optical appearance is identical to an adjacent steel panel. For use in the automotive industry, the composite material of Class A surface can be painted at the same time with a metal material by means of automatic vehicle painting or automatic part painting, to achieve the same appearance as the adjacent metal material.

So far, for the texture phenomenon of surface anisotropy caused by the fiber replication effect of the fiber reinforced composite material, different methods have been tried to overcome and solve it. One method is to solve the surface texture problem of the fiber reinforced composite material by the in-mold painting technique, to meet the application requirements of Class A surface. For example, U.S. Patent No. US 20050260389 describes the use of in-mold painting to enhance the appearance of a polyurethane-based composite material, to achieve the application requirements of Class A surface. Another method is to suppress the fiber replication effect by surface coating in a mold for preparing a composite material. For example, U.S. Patent No. US2010086737 discloses the use of a surface smoothing film equivalent to 100-800 grams per square meter coated on a composite material for suppressing the fiber replication effect to achieve the surface flatness and durability requirements for the composite material. U.S. Patent No. US2016075105 describes the use of a metal layer having Class A surface to treat the surface of a laminated composite material, to effect the use of the composite material in automotive exterior ornaments.

Here, the present application is intended to solve the problem of fiber textures on the surface of the fiber reinforced composite material by providing a new coating composition as a coating in the surface pretreatment of the composite material, so that the composite material has a surface meeting the painting requirement of the Class A surface, and can be used in subsequent continuous and mass painting.

SUMMARY

A first object of the present invention is to provide a method for surface treatment of a composite material, particularly a method for surface treatment of a fiber reinforced composite material, such that the composite material, especially the fiber reinforced composite material meets the painting requirement of Class A surface, thus obtaining a composite material/fiber reinforced composite material applicable to the continuous and mass painting of vehicles.

To achieve the above object, in an aspect of the present application, a method for surface treatment of a composite material is provided The treatment method comprises: coating at least one coating composition on at least one surface of a composite material, where the coating composition comprises at least a polyamine resin and at least a curing agent having an isocyanate group. The polyamine resin has at least two or more amino groups selected from one or more of a primary amino group and a secondary amino group.

In an embodiment, the composite material treated by the treatment method can be used to produce the automotive body or automotive exterior parts.

In an embodiment, the surface of the automotive body or automotive exterior parts meets the painting requirements of Class A surface.

In an embodiment, the coating composition is coated by spraying onto at least one surface of the composite material.

In an embodiment, the coating composition is coated by in-mold painting onto at least one surface of the composite material.

In an embodiment, the composite material is a fiber reinforced composite material.

In an embodiment, the fiber reinforced composite material is glass fiber reinforced composite material (e.g. Glass Fiber Reinforced Polymer/Plastics, GFRP) and a carbon fiber reinforced composite material (e.g. Carbon Fiber Reinforced Polymer/Plastics, CFRP) .

In an embodiment, the fiber reinforced composite material is a carbon fiber reinforced composite material.

In a preferred embodiment, a method for surface treatment of a fiber reinforced composite material is provided. The treatment method comprises: coating at least one coating composition on at least one surface of a fiber reinforced composite material, where the coating composition comprises at least a polyamine resin and at least a curing agent having an isocyanate group. The polyamine resin has at least two or more amino groups selected from one or more of a primary amino group and a secondary amino group.

According to another aspect of the present application, a coating composition is provided, which has the properties of low-temperature fast-curing and high cross-linking density. Moreover, the polyamine resin used in the coating composition of the present application can fully wet and level the surface of the fiber reinforced composite material, thus improving the ability of the coating composition to solve the fiber textures caused by the surface anisotropy of the fiber reinforced composite material, and ameliorating other defects on the surface of the composite material. In addition, the coating formed by the coating composition after low-temperature curing has high hardness and good toughness, and can effectively suppress the fiber replication effect caused by the volume change of the matrix resin in the composite material.

According to another aspect of the present application, a coating composition is provided for surface treatment of a composite material. The coating composition comprises at least a polyamine resin and at least a curing agent having an isocyanate group. The polyamine resin has at least two or more amino groups selected from one or more of a primary amino group and a secondary amino group.

In an embodiment, the composite material treated with the coating composition can be used to prepare the automotive body or automotive exterior parts.

In an embodiment, the polyamine resin is at least one selected from the group consisting of a primary amine-based polyamine resin and a primary amine modified polyamine resin having at least two or more amino groups.

In an embodiment, the primary amine-based polyamine resin is at least one selected from the group consisting of ethylenediamine, isophoronediamine, tetramethylenediamine, hexamethylenediamine, dodecamethylenediamine, m-xylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

In an embodiment, the primary amine modified polyamine resin is at least one selected from the group consisting of a polyether modified polyamine resin, an epoxy modified polyamine resin, a carbonyl modified polyamine resin, a phenolic modified polyamine resin, and a polyaspartate polyamine resin.

In an embodiment, the polyether modified polyamine resin includes polyamine resins modified with polyethers of various structures, for example, but not limited to JEFFAMINE D-230, JEFFAMINE D-2000, JEFFAMINE D-4000, or JEFFAMINE T-3000 commercially available from Huntsman.

In an embodiment, the epoxy modified polyamine resin includes, but is not limited to, for example, at least one selected from the group consisting of an adduct of an epoxy resin with an amine, an adduct of a glycidyl ether with an amine, and an adduct of an alkylene oxide and an amine.

In an embodiment, the carbonyl modified polyamine resin includes, but is not limited to, for example, ketoimine-based polyamine materials formed by reacting ethylenediamine or diethylenetriamine with acetone, butanone, or methyl isobutyl ketone.

In an embodiment, the phenolic modified polyamine resin includes, but is not limited to, for example, polyamine resins formed by ethylenediamine, hexamethylenediamine, diethylenetriamine, or metaphenylenediamine modified by formaldehyde, p-hydroxybenzaldehyde, phenol or octylphenol.

In an embodiment, the polyaspartate polyamine resin is a secondary amine-based polyamine resin having a sterically hindered group, for example, but not limited to, at least one selected from the group consisting of Desmophen NH1220, Desmophen NH1420, and Desmophen NH1520, commercially available from Bayer Material Science, and F220, F420, F520, F525, and F524 commercially available from Zhuhai Feiyang New Material Co., Ltd.

In an embodiment, the curing agent is at least one selected from the group consisting of a dimer, a trimer and a polymer of an aliphatic isocyanate monomer, an alicyclic isocyanate monomer, an aromatic isocyanate monomer or a hybrid isocyanate. That is, the curing agent may be at least one selected from the group consisting of a dimer, a trimer, and a polymer of an aliphatic isocyanate monomers, at least one selected from the group consisting of an alicyclic isocyanate monomer, or at least one selected from the group consisting of a dimer, a trimer, and a polymer of an aromatic isocyanate monomer.

In an embodiment, the aliphatic isocyanate monomer is at least one selected from the group consisting of tetramethylene 1, 4-diisocyanate, hexamethylene 1, 6-diisocyanate, 2, 2, 4-trimethylhexane 1, 6-diisocyanate, ethylene diisocyanate, and 1, 12-dodecane diisocyanate.

In an embodiment, the alicyclic isocyanate monomer is at least one selected from the group consisting 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.

In an embodiment, the aromatic isocyanate monomer is at least one selected from the group consisting 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.

In an embodiment, the dimeric, trimeric and polymeric curing agents of aliphatic, alicyclic, aromatic and hybrid isocyanates include, but are not limited to, for example, Desmodur N 3300, Desmodur N 3390, Desmodur N 3600, Desmodur N 3900 and Desmodur Z 4470 commercially available from Bayer Material Science or HDT-90, HDT-100 and HDT-LV commercially available from Rodia Group.

In an embodiment, the coating composition further comprises at least one solvent selected from the group consisting of toluene, xylene, isopropanol, n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, diethylene glycol methyl ether, propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol dimethyl ether, dipropylene glycol ethyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, dipropylene glycol methyl ether, ethylene glycol butyl ether acetate, ethylene glycol ethyl ether acetate, isophorone, diacetone alcohol, ethyl acetate, ethylene glycol ethyl ether, propylene glycol ethyl ether, and diethylene glycol butyl ether.

The solvent is used to dissolve the polyamine resin and the curing agent, respectively.

In a preferred embodiment, the solvent is a combined solvent, for example, but not limited to, a combined solvent of butyl acetate and methyl ethyl ketone in admixture, where the weight ratio of butyl acetate to methyl ethyl ketone ranges from 1: 2 to 2: 1, for example, 1: 1, 1: 1.5, and 1.5: 1.

In an embodiment, the coating composition further comprises at least one auxiliary agent selected from the group consisting of a substrate wetting agent, a leveling agent, an antifoaming agent, a thickener, a rheological additive, a pigment dispersant, and a photostabilizer. It will be understood by those skilled in the art that the auxiliary agents can be selected according to practical process requirements, and the scope of the present application is not limited by the auxiliary agents listed above.

In a preferred embodiment, the solid particles in the coating composition have a diameter of 10 μm or less.

In a preferred embodiment, the coating composition has a viscosity in the range of 100 to 20000 mPa·s at 23℃.

According to another aspect of the present application, a method for preparing the coating composition is provided, which comprises mixing the polyamine resin (and an auxiliary agent if applicable) with at least a first solvent to obtain a component I; mixing the curing agent with at least a second solvent to obtain a component II; and then mixing the component I and the component II uniformly to obtain the coating composition.

In an embodiment, the weight ratio of the component I to the component II ranges from 1: 20 to 20: 1.

In an embodiment, the content in percentages by weight of the polyamine resin in the component I is from 45%to 95%.

In an embodiment, the component I has a viscosity in the range of 100 to 20000 mPa·sat 23℃.

In an embodiment, the content in percentages by weight of the curing agent in the component II is 40-100%.

In an embodiment, the first solvent and the second solvent are the same or different solvents, and are at least one independently selected from the group consisting of toluene, xylene, isopropanol, n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, diethylene glycol methyl ether, propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol dimethyl ether, dipropylene glycol ethyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, dipropylene glycol methyl ether, ethylene glycol butyl ether acetate, ethylene glycol ethyl ether acetate, isophorone, diacetone alcohol, ethyl acetate, ethylene glycol ethyl ether, propylene glycol ethyl ether, diethylene glycol butyl ether, or a mixture of two or more thereof.

In an embodiment, the first solvent and the second solvent are the same solvent. Moreover, both the first solvent and the second solvent are a combined solvent, for example, but not limited to, a combined solvent of butyl acetate and methyl ethyl ketone in admixture, where the weight ratio of butyl acetate to methyl ethyl ketone ranges from 1: 2 to 2: 1, for example, 1: 1, 1: 1.5, and 1.5: 1.

According to another aspect of the present application, use of the coating composition in the surface treatment of a composite material, in particular a fiber reinforced composite material, is provided.

In an embodiment, the coating composition is coated as a pretreatment coating onto at least one surface of a composite material, particularly a fiber reinforced composite material.

As a surface coating or a pretreatment coating of the composite material or the fiber reinforced composite material, the coating composition can solve the problem of fiber textures on the surface of the composite material and particularly the fiber reinforced composite material, so that the composite material has a surface meeting the painting requirement of the Class A surface, and can be used in subsequent continuous and mass painting.

In a preferred embodiment, the coating composition can be coated on the surface of the fiber reinforced composite material surface by at least one of air spray, airless spray or in-line electrostatic spray. The coating composition can also be applied to the surface of the composite material by in-mold painting. At least one coating is formed on the surface of the composite material.

The coating composition of the present application can fully wet and level the surface of the fiber reinforced composite material by using the polyamine resin and a suitable solvent (especially a combined solvent) , thus improving the ability of the coating composition to solve the fiber textures caused by the surface anisotropy of the fiber reinforced composite material, and ameliorating other defects on the surface of the composite material. Meanwhile, a suitable curing agent and solvent are used in the coating composition described in the present application, such that the coating composition has the characteristics of low-temperature fast curing and high crosslinking density.

The coating formed by the coating composition of the present application after low-temperature curing has high hardness and good toughness, and can effectively suppress the fiber replication effect caused by the volume change of the matrix resin in the fiber reinforced composite material. In the coating composition described in the present application, a polyamine resin and an isocyanate group-containing curing agent are used, which enables the fiber reinforced composite material to meet the painting requirements of the Class A surface, and the coating composition also has high adhesion, good water resistance, stone crash protection, anti-impact toughness, weather resistance, chemical resistance and other characteristics.

Since the coating composition described in the present application can be coated on a component of a composite material having surface textures by air spraying, airless spraying, in-line electrostatic spray or in-mold painting, the surface of the coated component is allowed to reach the painting requirements of the Class A surface. When the coating composition described in the present application is applied to a fiber reinforced composite material, the surface properties of the fiber reinforced composite material can satisfy the process requirements of high-efficiency painting of automobile parts or vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cross-sectional view of an existing fiber reinforced composite material; and

Fig. 2 is a cross-sectional view of a fiber reinforced composite material according to an embodiment of the present application.

DETAILED DESCRIPTION

Hereinafter, the technology of the present application will be described in detail in conjunction with specific embodiments. It should be understood that the following specific embodiments are provided merely for facilitating the understanding of the present application by those skilled in the art to understand and not intended to limit the present application.

Example 1

In this Example, a coating composition 1 is provided, which comprises a polyamine resin and an isocyanate group-containing curing agent. The polyamine resin is a polyaspartate resin, for example, Desmophen NH1220 available from Bayer Material Science, and the isocyanate group-containing curing agent is an aliphatic isocyanate curing agent, for example, Desmodur N 3390 available from Bayer Material Science. The coating composition further comprises a solvent and an auxiliary agent, and the auxiliary agent includes a substrate wetting agent, a pigment dispersant, fumed silica, a pigment and filler, a photostabilizer, and an UV absorber. The solvent is a combined solvent of butyl acetate and methyl ethyl ketone in admixture, where the weight ratio of butyl acetate to methyl ethyl ketone ranges from 1: 2 to 2: 1, for example, 1: 1, 1: 1.5, and 1.5: 1.

A method for preparing the coating composition is specifically as follows.

1) A polyaspartate resin A, butyl acetate, butyl acetate, methyl ethyl ketone, a pigment and filler, a dispersant, and a fumed silica thickener are sequentially added to a primary container, mixed uniformly by dispersing for 20-30 min by using a high-speed disperser with stirring at a speed of 1500-2000 rpm.

2) The uniformly mixed materials are transferred to a grinding machine and ground, and the grinding endpoint of the material is controlled by the fineness of the slurry, where the discharge fineness of the material is 10 μm or less.

3) A commercially available substrate wetting agent, a commercially available photostabilizer, and a commercially available UV absorber are added to the slurry obtained in the step (2) , and dispersed at a high speed to mix the coating uniformly, so as to obtain a component I. The viscosity of the component I is adjusted with methyl acetate and methyl ethyl ketone, and the component I is stirred for 15 min before each viscosity measurement. The component I has a viscosity in the range of 100 to 20000 mPa·s at 23℃.

4) The aliphatic isocyanurate curing agent Desmodur N 3390 and the solvent butyl acetate are mixed uniformly at a certain ratio by stirring, to obtain a component II of the pretreatment coating, in which the content in percentages by weight of the curing agent in the component II is 40-100%.

5) In use, the component I and the component II are uniformly mixed at a weight ratio of 1: 20 to 20: 1 by stirring, adjusted to the applicable viscosity, sprayed onto the composite material CFRP-1 with fiber textures, and cured for 30 min at room temperature. The extent of the texture on the surface of the composite material after spraying the coating is visually observed after painting.

The parts by weight of each component in the component I are listed in Table 1 below.

Table 1. Parts by weight of each component in component I

Example 2

In this Example, a coating composition 2 is provided, which comprises a polyamine resin and an isocyanate group-containing curing agent. The polyamine resin is a polyaspartate resin, for example, F420 available from Zhuhai Feiyang New Material Co., Ltd., and the isocyanate group-containing curing agent is an aliphatic isocyanate group-containing curing agent, for example, Desmodur N 3390 available from Bayer Material Science. The coating composition further comprises a solvent and an auxiliary agent, and the auxiliary agent includes a substrate wetting agent, a pigment dispersant, fumed silica, a pigment and filler, a photostabilizer, and an UV absorber. The solvent is a combined solvent of butyl acetate and methyl ethyl ketone in admixture, where the weight ratio of butyl acetate to methyl ethyl ketone ranges from 1: 2 to 2: 1, for example, 1: 1, 1: 1.5, and 1.5: 1.

A method for preparing the coating composition 2 is the same as that in Example 1. The extent of the texture on the surface of the composite material after spraying the coating is visually observed after painting.

Example 3

In this Example, a coating composition 3 is provided, which comprises a polyamine resin and an isocyanate group-containing curing agent. The polyamine resin is a polyaspartate resin, for example, Desmophen NH1420 available from Bayer Material Science, and the isocyanate group-containing curing agent is an aliphatic isocyanate group-containing curing agent, for example, Desmodur N 3900 available from Bayer Material Science. The coating composition further comprises a solvent and an auxiliary agent, and the auxiliary agent includes a substrate wetting agent, a pigment dispersant, fumed silica, a pigment and filler, a photostabilizer, and an UV absorber. The solvent is a combined solvent of butyl acetate and methyl ethyl ketone in admixture, where the weight ratio of butyl acetate to methyl ethyl ketone ranges from 1: 2 to 2: 1, for example, 1: 1, 1: 1.5, and 1.5: 1.

A method for preparing the coating composition 3 is the same as that in Example 1. The extent of the texture on the surface of the composite material after spraying the coating is visually observed after painting.

Example 4

In this example, the coating composition 1 is coated on the composite materials CFRP-1 and CFRP-2, respectively. In this example, the coating composition 1 is coated on the composite materials CFRP-1 and CFRP-2 by spraying, and the coating is controlled to have a thickness of 0.3 mm, and cured at room temperature for 30 min. The extent of the texture on the surface of the composite material after spraying the coating is visually observed after painting.

Example 5

The pretreatment coating composition 1 prepared by the method described above and the control two-component polyurethane varnish coating marketed under the trademark CLEARCOAT 859-0-411 by NIPPON PAINT are used. Similarly, a 0.3 mm-thick coating is formed on the composite material CFRP-1 with the CLEARCOAT 859-0-411 two-component polyurethane varnish, and cured at 80℃ for 30 min. The extent of surface texture of the composite material is visually observed after the coating is sprayed.

Test results

The evaluation criteria are: 0: no surface texture is observed at all; 1: surface texture is substantially not observed; 2: slight surface texture is observed; 3: obvious surface texture is observed; and 4: very conspicuous surface texture is observed. The test results shown in Table 2 are obtained.

Table 2. Test results of surface texture

The results in Table 2 indicate that the ability to solve the textures on the surface of the composite material varies with different types of polyaspartate resins in the pretreatment coating composition. For composite materials with different surface fiber textures, a pretreatment coating with the same polyaspartate resin and thickness has different abilities to solve the surface texture. Compared with the two-component polyurethane varnish with the same film thickness cured at 80℃, the coating compositions 1-3 cured at room temperature have obviously better ability to solve the surface fiber texture of the composite material CFRP-1.

The coating composition of the present application is enabled to have the properties of high solid content and low viscosity and can fully wet and level the surface of the fiber reinforced composite material by using the low-molecular-weight polyamine resin and a suitable solvent (especially a combined solvent) in the coating composition, thus improving the ability of the coating composition to solve the fiber textures caused by the surface anisotropy of the fiber reinforced composite material, and ameliorating other defects on the surface of the composite material. Meanwhile, a suitable curing agent and solvent are used in the coating composition described in the present application, such that the coating composition has the characteristics of low-temperature fast curing and high crosslinking density.

Since the coating composition described in the present application has the properties of high solid content and low viscosity, and can be coated on a component of a composite material having surface textures by air spraying, airless spraying, in-line electrostatic spray or in-mold painting, the surface of the coated component is allowed to reach the painting requirements of the Class A surface. When the coating composition described in the present application is applied to a fiber reinforced composite material, the surface properties of the fiber reinforced composite material can satisfy the process requirements of high-efficiency painting of automobile parts or vehicle.

The present application has been described through the above related embodiments, but the above embodiments are merely examples for implementing the present application. It needs to be noted that the disclosed embodiments do not limit the scope of the application. Rather, modifications and equivalent arrangements are intended to be included within the scope of the appended claims.

Claims

A coating composition for the surface treatment of a composite material, comprising at least a polyamine resin and at least a curing agent having an isocyanate group, wherein the polyamine resin has at least two or more amino groups selected from one or more of a primary amino group and a secondary amino group.
The coating composition according to claim 1, wherein the polyamine resin is at least one selected from the group consisting of a primary amine-based polyamine resin and a primary amine modified polyamine resin having at least two or more amino groups.
The coating composition according to claim 1, wherein the solid particles in the coating composition have a diameter of 10 μm or less.
The coating composition according to claim 1, having a viscosity in the range of 100-20000 mPa·s at 23℃.
The coating composition according to claim 2, wherein the primary amine-based polyamine resin is at least one selected from the group consisting of ethylenediamine, isophoronediamine, tetramethylenediamine, hexamethylenediamine, dodecamethylenediamine, m-xylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine; and the primary amine modified polyamine resin is at least one selected from the group consisting of a polyether modified polyamine resin, an epoxy modified polyamine resin, a carbonyl modified polyamine resin, a phenolic modified polyamine resin, and a polyaspartate polyamine resin.
The coating composition according to claim 1, wherein the curing agent is at least one selected from the group consisting of a dimer, a trimer and a polymer of an aliphatic isocyanate monomer, an alicyclic isocyanate monomer, an aromatic isocyanate monomer or a hybrid isocyanate.
The coating composition according to claim 4, wherein

the aliphatic isocyanate monomer is at least one selected from the group consisting of tetramethylene 1, 4-diisocyanate, hexamethylene 1, 6-diisocyanate, 2, 2, 4-trimethylhexane 1, 6-diisocyanate, ethylene diisocyanate, and 1, 12-dodecane diisocyanate;

the alicyclic isocyanate monomer is at least one selected from the group consisting 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; and

the aromatic isocyanate monomer is at least one selected from the group consisting 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.
The coating composition according to claim 1, further comprising at least one solvent selected from the group consisting of toluene, xylene, isopropanol, n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, diethylene glycol methyl ether, propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol dimethyl ether, dipropylene glycol ethyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, dipropylene glycol methyl ether, ethylene glycol butyl ether acetate, ethylene glycol ethyl ether acetate, isophorone, diacetone alcohol, ethyl acetate, ethylene glycol ethyl ether, propylene glycol ethyl ether, and diethylene glycol butyl ether.
The coating composition according to claim 1, further comprising at least one auxiliary agent selected from the group consisting of a substrate wetting agent, a leveling agent, an antifoaming agent, a thickener, a rheological additive, a pigment dispersant, and a photostabilizer.
A method for surface treatment of a composite material, comprising coating at least a coating composition according to claim 1 onto at least a surface of the composite material.
The treatment method according to claim 10, wherein the composite material treated by the treatment method is used to produce the automotive body or automotive exterior parts, such that the surface of the automotive body or the automotive exterior parts meets the painting requirements of the Class A surface.
The treatment method according to claim 10, wherein the coating composition is coated by spraying onto the at least one surface of the composite material.
The treatment method according to claim 10, wherein the coating composition is coated by in-mold painting onto the at least one surface of the composite material.
The treatment method according to claim 10, wherein the composite material is a fiber reinforced composite material.
The treatment method according to claim 12, wherein the fiber reinforced composite material is a glass fiber reinforced composite material or a carbon fiber reinforced composite material.
A method for preparing a coating composition according to claim 1, comprising the following steps: mixing at least a polyamine resin with at least a first solvent to obtain a component I; mixing at least a curing agent with at least a second solvent to obtain a component II; and then mixing the component I and the component II uniformly to obtain the coating composition, wherein

the weight ratio of the component I to the component II ranges from 1: 20 to 20: 1.
The preparation method according to claim 16, wherein the content in percentages by weight of the polyamine resin in the component I is from 45%to 95%.
The preparation method according to claim 16, wherein the component I has a viscosity in the range of 100 -20000 mPa·s at 23℃.
The preparation method according to claim 16, wherein the content in percentages by weight of the curing agent in the component II is from 40%to 100%.
The preparation method according to claim 16, wherein the first solvent and the second solvent are the same or different solvents, and are at least one selected from the group consisting of toluene, xylene, isopropanol, n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, diethylene glycol methyl ether, propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol dimethyl ether, dipropylene glycol ethyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, dipropylene glycol methyl ether, ethylene glycol butyl ether acetate, ethylene glycol ethyl ether acetate, isophorone, diacetone alcohol, ethyl acetate, ethylene glycol ethyl ether, propylene glycol ethyl ether, diethylene glycol butyl ether, or a mixture of two or more thereof.