A solid gel coat and a preparation method and application thereof, and a preparation method of a surface film composite material

Abstract

The application provides a solid glue coating, a preparation method and application thereof, and a preparation method of a surface-coated composite material, and belongs to the technical field of functional materials.The solid glue coating provided by the application comprises the following preparation raw materials in mass fractions: 50-95 parts of base resin powder, 1-20 parts of graphene oxide-nano titanium dioxide composite material, 1-20 parts of barium sulfate, 0.1-10 parts of a curing agent, 0.01-5 parts of a defoaming agent, and 0.01-5 parts of a wetting and leveling agent.The solid glue coating provided by the application is a high-thermal-conductivity and high-fluidity composite resin powder, can be coated on the inner surface of a mold in the forming stage of a composite material product, and is heated and solidified together with a composite material matrix, wherein the solid glue coating forms a uniform, smooth and dense coating on the surface of the composite material matrix, is perfectly fused with the composite material matrix, and thus an integrally-formed surface-coated composite material is obtained, and the operation is simple and environment-friendly.

Description

A solid gel coat, its preparation method and application, and a method for preparing surface-coated composite materials. Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to a solid gel coat, its preparation method and application, and a method for preparing surface-coated composite materials. Background Technology

[0002] Currently, composite materials are widely used, and compression molding is one of the main methods for preparing composite materials. However, the surface properties or quality of composite products prepared by compression molding often cannot meet actual needs. Therefore, it is necessary to add a coating to the surface of the product to make it denser and more aesthetically pleasing, and to achieve various performance improvements. Currently, baking paint or coating processes are mainly used to prepare the coating. These processes require cleaning the product surface before painting and curing; additional equipment and procedures are required, which is time-consuming and resource-intensive. Moreover, the paints used usually contain organic solvents, which can easily cause solvent evaporation and environmental pollution. Summary of the Invention

[0003] The purpose of this invention is to provide a solid gel coat, its preparation method and application, and a method for preparing surface-coated composite materials. The preparation of surface-coated composite materials using the solid gel coat provided by this invention is simple to operate and environmentally friendly.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a solid gel coat, comprising the following raw materials by weight:

[0006] The mixture contains 50-95 parts of base resin powder, 1-20 parts of graphene oxide-nano titanium dioxide composite material, 1-20 parts of barium sulfate, 0.1-10 parts of curing agent, 0.01-5 parts of defoamer, and 0.01-5 parts of wetting and leveling agent.

[0007] Preferably, the graphene oxide-nano titanium dioxide composite material is obtained by modifying graphene oxide and nano titanium dioxide with a silane coupling agent.

[0008] Preferably, the graphene oxide is a single-layer graphene oxide with a sheet diameter of 0.5–5 μm and a single-layer thickness of 0.8–1.2 nm; the nano-titanium dioxide is rutile titanium dioxide with a particle size of 15–30 nm.

[0009] Preferably, the silane coupling agent includes one or more of KH550, KH560 and KH570.

[0010] Preferably, the graphene oxide-nano titanium dioxide composite material is prepared by any one of methods (1) to (3);

[0011] The method (1) includes the following steps: mixing graphene oxide, nano-titanium dioxide, silane coupling agent and organic solvent, and performing a first modification treatment to obtain the graphene oxide-nano-titanium dioxide composite material.

[0012] The method (2) includes the following steps: mixing nano-titanium dioxide, silane coupling agent and organic solvent, and performing a second modification treatment to obtain modified nano-titanium dioxide; mixing graphene oxide, modified nano-titanium dioxide, silane coupling agent and organic solvent, and performing a third modification treatment to obtain the graphene oxide-nano-titanium dioxide composite material.

[0013] The method (3) includes the following steps: mixing nano-titanium dioxide, silane coupling agent and organic solvent, and performing a fourth modification treatment to obtain modified nano-titanium dioxide; mixing graphene oxide, silane coupling agent and organic solvent, and performing a fifth modification treatment to obtain modified graphene oxide; and mixing the modified nano-titanium dioxide and modified graphene oxide to obtain the graphene oxide-nano-titanium dioxide composite material.

[0014] Preferably, the base resin powder includes epoxy resin, polyester resin, polyurethane resin, or acrylic resin.

[0015] This invention provides a method for preparing the solid gel coat described in the above technical solution, comprising the following steps:

[0016] The raw materials for preparing solid gelcoat are mixed to obtain the solid gelcoat.

[0017] This invention provides the application of the solid gel coat described in the above technical solution or the solid gel coat prepared by the preparation method described in the above technical solution in the preparation of surface-coated composite materials.

[0018] This invention provides a method for preparing a surface-coated composite material, comprising the following steps:

[0019] A solid gel coat is applied to the inner surface of a preheated molding die, and then the composite material matrix is ​​placed in the cavity of the molding die for molding and curing, so that the surface of the composite material matrix is ​​coated with a coating formed by the solid gel coat, thus obtaining the surface-coated composite material.

[0020] Preferably, the composite matrix is ​​a fiber-reinforced resin material; the resin material in the fiber-reinforced resin material includes epoxy resin, polyester resin, polyurethane resin or acrylic resin, and the reinforcing fibers in the fiber-reinforced resin material include glass fiber, carbon fiber, basalt fiber, hemp fiber, bamboo fiber or wood fiber.

[0021] This invention provides a solid gelcoat, comprising, by weight, the following raw materials: 50-95 parts of base resin powder, 1-20 parts of graphene oxide-nano titanium dioxide composite material, 1-20 parts of barium sulfate, 0.1-10 parts of curing agent, 0.01-5 parts of defoamer, and 0.01-5 parts of wetting and leveling agent. The solid gelcoat provided by this invention is a high thermal conductivity and high fluidity composite resin powder, which can be coated onto the inner surface of the mold during the molding stage of composite material products and cured together with the composite material matrix. The solid gelcoat forms a uniform, smooth, and dense coating on the surface of the composite material matrix, perfectly fusing with the matrix to obtain an integrally molded surface-coated composite material. The process is simple, environmentally friendly, and easily adaptable to various functional requirements of composite material products. Furthermore, the addition of graphene oxide-nano titanium dioxide composite material to the solid gelcoat provided by this invention effectively improves the wear resistance and weather resistance of the coating formed by the solid gelcoat. Specifically, the surface of graphene oxide is rich in oxygen-containing functional groups. After modification with a silane coupling agent, it can be fully dispersed in the resin matrix, giving full play to the high thermal conductivity of graphene oxide. This allows for a rapid temperature increase, enabling the solid gel coat to fully melt and wet the mold surface. Furthermore, the excellent mechanical properties and nanosheet structure of graphene oxide improve the surface barrier properties of the coating, effectively enhancing its weather resistance and solvent resistance. Nano-titanium dioxide fills the voids in the graphene oxide layer structure, achieving perfect dispersion. It forms a strong interfacial bond with the resin matrix, thus improving the coating's strength, hardness, and wear resistance, and enhancing its UV shielding performance, resulting in excellent weather resistance. Simultaneously, the solid gel coat provided by this invention does not use organic solvents, eliminating solvent evaporation and making it safe and environmentally friendly. Detailed Implementation

[0022] This invention provides a solid gel coat, comprising the following raw materials by weight:

[0023] The mixture contains 50-95 parts of base resin powder, 1-20 parts of graphene oxide-nano titanium dioxide composite material, 1-20 parts of barium sulfate, 0.1-10 parts of curing agent, 0.01-5 parts of defoamer, and 0.01-5 parts of wetting and leveling agent.

[0024] Unless otherwise specified, all raw materials used in this invention are commercially available resins that are known to those skilled in the art.

[0025] The raw materials for preparing the solid gel coat of the present invention, by weight, include 50-95 parts of base resin powder, preferably 60-90 parts, more preferably 65-85 parts, and even more preferably 70-80 parts, specifically 74.5 parts, 75.5 parts, 76.5 parts, 77.5 parts, or 78.5 parts. In the present invention, the base resin powder preferably includes epoxy resin, polyester resin, polyurethane resin, or acrylic resin, more preferably polyester resin; in the embodiments of the present invention, the polyester resin is specifically purchased from Zhejiang Guanghua Technology Co., Ltd., model GH-6609.

[0026] Based on the mass fraction of the base resin powder, the raw materials for preparing the solid gel coat of the present invention include 1 to 20 parts of graphene oxide-nano titanium dioxide composite material, preferably 5 to 15 parts, specifically 7, 8, 9, 10, 11, or 12 parts. In the present invention, the graphene oxide-nano titanium dioxide composite material is preferably obtained by modifying graphene oxide and nano titanium dioxide with a silane coupling agent. In the present invention, the graphene oxide is preferably monolayer graphene oxide, the sheet size of the graphene oxide is preferably 0.5 to 5 μm, and the monolayer thickness of the graphene oxide is preferably 0.8 to 1.2 nm. In the present invention, the nano titanium dioxide is preferably rutile titanium dioxide, and the particle size of the nano titanium dioxide is preferably 15 to 30 nm. In the present invention, the silane coupling agent preferably includes one or more of KH550, KH560, and KH570, more preferably KH550, KH560, or KH570. In this invention, the preferred mass ratio of graphene oxide, nano-titanium dioxide, and silane coupling agent is 5:3–15:5–65, more preferably 5:6–15:20–50, further preferably 5:9–15:25–45, and even more preferably 5:9–10:30–40. In this invention, the graphene oxide-nano-titanium dioxide composite material effectively improves the abrasion resistance (scratch resistance) of solid gel coats. Specifically, graphene is a single-layer two-dimensional crystal structure formed from carbon atoms, possessing excellent mechanical strength, electrical conductivity, and thermal conductivity. Due to its single-layer structure and highly ordered lattice, graphene also exhibits excellent gas and liquid barrier properties, effectively preventing the penetration of substances such as water vapor, oxygen, and carbon dioxide. Furthermore, graphene also possesses flexibility and corrosion resistance. Graphene oxide (GO) is the most important derivative of graphene. Its surface and edges are rich in oxygen-containing functional groups such as hydroxyl, carboxyl, epoxy, and carbonyl groups. After modification with silane coupling agents, it can be fully dispersed in the resin matrix, giving full play to the high thermal conductivity of graphene oxide. It can raise the temperature in a short time, allowing the solid gel coat to fully melt and wet the mold surface. Moreover, the excellent mechanical properties and nanosheet structure of graphene oxide can improve the surface barrier properties of the coating, effectively improving the coating's weather resistance and solvent resistance. Nano-titanium dioxide can fill the gaps in the graphene oxide layer structure to achieve a perfect dispersion effect. It forms a strong interfacial bond with the resin matrix, thus improving the coating's strength, hardness, and wear resistance, and enhancing its ultraviolet shielding performance, giving the coating excellent weather resistance.

[0027] In this invention, the graphene oxide-nano titanium dioxide composite material is preferably prepared by any one of methods (1) to (3), which will be described in detail below.

[0028] In this invention, method (1) preferably includes the following steps:

[0029] Graphene oxide, nano-titanium dioxide, silane coupling agent and organic solvent are mixed and subjected to a first modification treatment to obtain the graphene oxide-nano-titanium dioxide composite material.

[0030] In this invention, graphene oxide is preferably dispersed in an organic solvent, and then nano-titanium dioxide and a silane coupling agent are added and stirred to obtain a mixed solution; the organic solvent is preferably ethanol; the ratio of graphene oxide to organic solvent is preferably 5g:250-350mL, more preferably 5g:300mL. In this invention, the nano-titanium dioxide is preferably used in the form of a nano-titanium dioxide suspension, and the dispersion medium in the nano-titanium dioxide suspension is preferably an aqueous ethanol solution; the solid content of the nano-titanium dioxide suspension is preferably 30wt%. In the embodiments of this invention, the nano-titanium dioxide suspension is specifically purchased from Hangzhou Hengna Company; the graphene oxide is specifically purchased from Xianfeng Nano Company. In this invention, the stirring and mixing time is preferably 0.5-1h.

[0031] After obtaining the mixed liquid, the present invention performs a first modification treatment on the mixed liquid to obtain the graphene oxide-nano titanium dioxide composite material. In the present invention, the temperature of the first modification treatment is preferably 50-80℃, more preferably 60-70℃, specifically the first modification treatment is performed under reflux conditions; the time of the first modification treatment is preferably 2-5 hours, more preferably 2-3 hours. After the first modification treatment, the present invention preferably cools the obtained product system to room temperature, and then performs solid-liquid separation, and dries the obtained solid material to obtain the graphene oxide-nano titanium dioxide composite material. In the present invention, the cooling is preferably natural cooling; the solid-liquid separation method is preferably centrifugal separation; the drying is preferably vacuum drying, and the temperature of the vacuum drying is preferably 25-60℃, more preferably 30-40℃. The present invention does not have a special limitation on the vacuum drying time, as long as sufficient drying is achieved.

[0032] This invention employs a silane coupling agent to modify graphene oxide and nano-titanium dioxide in the same system. During the modification process, the silane coupling agent is grafted onto both graphene oxide and nano-titanium dioxide, and the nano-titanium dioxide is uniformly dispersed in the gaps of the graphene oxide layer structure, enabling it to work synergistically with graphene oxide to better enhance the wear resistance of the solid gel coat.

[0033] In this invention, method (2) preferably includes the following steps:

[0034] Nano-titanium dioxide, silane coupling agent and organic solvent are mixed and subjected to a second modification treatment to obtain modified nano-titanium dioxide;

[0035] Graphene oxide, modified nano-titanium dioxide, silane coupling agent and organic solvent are mixed and subjected to a third modification treatment to obtain the graphene oxide-nano-titanium dioxide composite material.

[0036] This invention involves mixing nano-titanium dioxide, a silane coupling agent, and an organic solvent, followed by a second modification treatment to obtain modified nano-titanium dioxide. In this invention, the organic solvent is preferably ethanol. Preferably, the nano-titanium dioxide is used in the form of a nano-titanium dioxide suspension, wherein the dispersion medium in the nano-titanium dioxide suspension is preferably an aqueous ethanol solution; the solid content of the nano-titanium dioxide suspension is preferably 30 wt%. In embodiments of this invention, the nano-titanium dioxide suspension is specifically purchased from Hangzhou Hengna Company; the graphene oxide is specifically purchased from Xianfeng Nano Company. Preferably, this invention involves mixing the nano-titanium dioxide suspension with a silane coupling agent, then adding an organic solvent and stirring to obtain a nano-titanium dioxide-silane coupling agent mixture; the concentration of nano-titanium dioxide in the nano-titanium dioxide-silane coupling agent mixture is preferably 0.1–0.15 g / mL, more preferably 0.12 g / mL, and the concentration of the silane coupling agent is preferably 0.2–0.3 g / mL, more preferably 0.25 g / mL. In this invention, the mixing time is preferably 0.5 to 1 hour.

[0037] After obtaining the nano-titanium dioxide-silane coupling agent mixture, the present invention performs a second modification treatment on the nano-titanium dioxide-silane coupling agent mixture to obtain modified nano-titanium dioxide. In the present invention, the temperature of the second modification treatment is preferably 50-80℃, more preferably 60-70℃, specifically the second modification treatment is carried out under reflux conditions; the time of the second modification treatment is preferably 1-5 hours, more preferably 1.5-2 hours. After the second modification treatment, the present invention preferably cools the obtained product system to room temperature, and then performs solid-liquid separation, and dries the obtained solid material to obtain the modified nano-titanium dioxide. In the present invention, the cooling is preferably natural cooling; the solid-liquid separation method is preferably centrifugal separation; the drying is preferably vacuum drying, and the temperature of the vacuum drying is preferably 25-60℃, more preferably 35-45℃. The present invention does not have a special limitation on the vacuum drying time, as long as sufficient drying is achieved.

[0038] After obtaining modified nano-titanium dioxide, the present invention mixes graphene oxide, modified nano-titanium dioxide, silane coupling agent, and organic solvent for a third modification treatment to obtain the graphene oxide-nano-titanium dioxide composite material. In the present invention, the organic solvent is preferably ethanol. In the present invention, the preferred ratio of graphene oxide, silane coupling agent, and organic solvent is 5g:35-45g:250-350mL, more preferably 5g:40g:300mL. The present invention preferably disperses graphene oxide in an organic solvent, then adds the silane coupling agent and modified nano-titanium dioxide and stirs to obtain a mixed solution. In the present invention, the stirring time is preferably 0.5-1h.

[0039] After obtaining the mixed liquid, the present invention performs a third modification treatment on the mixed liquid to obtain the graphene oxide-nano titanium dioxide composite material. In the present invention, the temperature of the third modification treatment is preferably 50-80℃, more preferably 60-70℃, specifically the third modification treatment is carried out under reflux conditions; the time of the third modification treatment is preferably 1-5 hours, more preferably 1.5-2 hours. After the third modification treatment, the present invention preferably cools the obtained product system to room temperature, and then performs solid-liquid separation, and dries the obtained solid material to obtain the graphene oxide-nano titanium dioxide composite material. In the present invention, the cooling is preferably natural cooling; the solid-liquid separation method is preferably centrifugal separation; the drying is preferably vacuum drying, and the temperature of the vacuum drying is preferably 25-60℃, more preferably 35-45℃. The present invention does not have a special limitation on the vacuum drying time, as long as sufficient drying is achieved.

[0040] In this invention, method (3) preferably includes the following steps:

[0041] Nano-titanium dioxide, silane coupling agent and organic solvent are mixed and subjected to a fourth modification treatment to obtain modified nano-titanium dioxide;

[0042] Graphene oxide, silane coupling agent and organic solvent are mixed and subjected to the fifth modification treatment to obtain modified graphene oxide.

[0043] The modified nano-titanium dioxide was mixed with modified graphene oxide to obtain the graphene oxide-nano-titanium dioxide composite material.

[0044] This invention involves mixing nano-titanium dioxide, a silane coupling agent, and an organic solvent, followed by a fourth modification treatment to obtain modified nano-titanium dioxide. In this invention, the method for preparing the modified nano-titanium dioxide is preferably consistent with the above-described technical solution and will not be repeated here.

[0045] This invention involves mixing graphene oxide, a silane coupling agent, and an organic solvent, followed by a fifth modification treatment to obtain modified graphene oxide. In this invention, the organic solvent is preferably ethanol. The preferred ratio of graphene oxide, silane coupling agent, and organic solvent is 5g:35-45g:250-350mL, more preferably 5g:40g:300mL. Preferably, graphene oxide is dispersed in an organic solvent, and then the silane coupling agent is added and stirred to obtain a mixed solution. The preferred stirring time is 0.5-1 hour.

[0046] After obtaining the mixed liquid, the present invention performs a fifth modification treatment on the mixed liquid to obtain the modified graphene oxide. In the present invention, the temperature of the fifth modification treatment is preferably 50-80℃, more preferably 60-70℃, specifically the fifth modification treatment is performed under reflux conditions; the time of the fifth modification treatment is preferably 1-5 hours, more preferably 1.5-2 hours. After the fifth modification treatment, the present invention preferably cools the obtained product system to room temperature, and then performs solid-liquid separation, and dries the obtained solid material to obtain the graphene oxide-nano titanium dioxide composite material. In the present invention, the cooling is preferably natural cooling; the solid-liquid separation method is preferably centrifugal separation; the drying is preferably vacuum drying, and the temperature of the vacuum drying is preferably 25-60℃, more preferably 35-45℃. The present invention does not have a special limitation on the time of vacuum drying, as long as sufficient drying is achieved.

[0047] After obtaining modified graphene oxide and modified nano-titanium dioxide, the present invention mixes the modified graphene oxide with the modified graphene oxide to obtain the graphene oxide-nano-titanium dioxide composite material. The present invention does not have any particular limitation on the mixing method of the modified graphene oxide with the modified graphene oxide, as long as the two are mixed uniformly.

[0048] Based on the mass fraction of the base resin powder, the raw materials for preparing the solid gel coat of the present invention include 1 to 20 parts of barium sulfate, preferably 5 to 15 parts, and more preferably 8 to 9 parts. In the present invention, the barium sulfate can improve the creep resistance of the coating formed by the solid gel coat, improve the coating hardness, improve the heat resistance, and has good hiding power.

[0049] Based on the mass fraction of the base resin powder, the raw materials for preparing the solid gel coat of the present invention include 0.1 to 10 parts of curing agent, preferably 1 to 8 parts, more preferably 3 to 6 parts, and even more preferably 4 parts. In the present invention, the curing agent preferably includes triglycidyl isocyanurate (TGIC) or β-hydroxyalkylamide curing agent (β-HAA), more preferably triglycidyl isocyanurate. In the embodiments of the present invention, the triglycidyl isocyanurate was specifically purchased from Hunan Yunke Chemical Co., Ltd.

[0050] Based on the mass fraction of the base resin powder, the raw materials for preparing the solid gel coat of the present invention include 0.01 to 5 parts of defoamer, preferably 0.1 to 1.5 parts, more preferably 0.3 to 0.8 parts, and even more preferably 0.5 parts. In the present invention, the defoamer preferably includes one or more of benzoin, beeswax, and polysiloxane, more preferably benzoin.

[0051] Based on the mass fraction of the base resin powder, the raw materials for preparing the solid gel coat of the present invention include 0.01 to 5 parts of a wetting and leveling agent, preferably 0.1 to 1.5 parts, more preferably 0.3 to 0.8 parts, and even more preferably 0.5 parts. In the present invention, the wetting and leveling agent is preferably one or more of silicone-based, acrylic-based, or fluorocarbon-based wetting and leveling agents, and is further optimized to be a silicone-based wetting and leveling agent, specifically wetting and leveling agent HY-5057; in the embodiments of the present invention, the wetting and leveling agent HY-5057 is specifically purchased from Beijing Maier Chemical Technology Co., Ltd.

[0052] This invention provides a method for preparing the solid gel coat described in the above technical solution, comprising the following steps:

[0053] The raw materials for preparing solid gelcoat are mixed to obtain the solid gelcoat.

[0054] The present invention preferably involves adding graphene oxide-nano titanium dioxide composite material, barium sulfate, curing agent, defoamer, and wetting and leveling agent to a base resin powder and mixing them to obtain the solid gel coat. The present invention does not specifically limit the mixing method, as long as thorough mixing is ensured.

[0055] This invention provides the application of the solid gel coat described in the above technical solution or the solid gel coat prepared by the preparation method described in the above technical solution in the preparation of surface-coated composite materials.

[0056] This invention provides a method for preparing a surface-coated composite material, comprising the following steps:

[0057] A solid gel coat is applied to the inner surface of a preheated molding die, and then the composite material matrix is ​​placed in the cavity of the molding die for molding and curing, so that the surface of the composite material matrix is ​​coated with a coating formed by the solid gel coat, thus obtaining the surface-coated composite material.

[0058] This invention involves coating a solid gel coat onto the inner surface of a preheated molding die. Before coating the solid gel coat, the molding die is preheated, preferably at a temperature of 70–120°C, more preferably 100–120°C, and even more preferably 110–120°C. After preheating, the solid gel coat is coated onto the inner surface of the preheated molding die. In this invention, the coating method is preferably spraying, more preferably electrostatic spraying. This invention does not specifically limit the coating conditions, as long as the solid gel coat is uniformly coated onto the inner surface of the molding die. In this invention, the coating thickness of the solid gel coat is preferably 30–150 μm, more preferably 80–100 μm.

[0059] After applying a solid gel coat, the present invention places the composite material matrix within the cavity of the molding die and performs molding and curing, thereby coating the surface of the composite material matrix with a coating formed by the solid gel coat, resulting in the surface-coated composite material. In the present invention, the composite material matrix is ​​preferably a fiber-reinforced resin material, which preferably comprises a resin material and reinforcing fibers dispersed within the resin material. In the present invention, the resin material in the fiber-reinforced resin material preferably includes epoxy resin, polyester resin, polyurethane resin, or acrylic resin, more preferably polyester resin; the reinforcing fibers in the fiber-reinforced resin material preferably include glass fiber, carbon fiber, basalt fiber, hemp fiber, bamboo fiber, or wood fiber, more preferably glass fiber. The present invention does not have a particular limitation on the size of the reinforcing fibers, which can be short fibers, long fibers, or continuous fibers.

[0060] In this invention, after applying the solid gel coat, it is preferable to maintain a preheated temperature to allow the solid gel coat to melt and wet the inner surface of the molding die. During this heat maintenance, the composite material matrix is ​​placed inside the cavity of the molding die. After the heat maintenance, the temperature is raised for molding curing. In this invention, the heat maintenance time after applying the solid gel coat is preferably 20–60 s, more preferably 23–45 s, and even more preferably 25–35 s. In this invention, the molding curing temperature is preferably 130–180 °C, more preferably 140–170 °C, and even more preferably 150–160 °C; the molding curing time is preferably 10–120 min, more preferably 20–50 min, and even more preferably 25–30 min. After molding curing, the surface-coated composite material is preferably demolded. Using the solid gel coat of this invention, an integrally molded surface-coated composite material can be prepared; the operation is simple and environmentally friendly.

[0061] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0062] The sources of the raw materials used in the following embodiments and comparative examples of this invention are as follows:

[0063] The graphene oxide was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd. It is a single-layer graphene oxide with a sheet size of 0.5-5 μm, a single-layer thickness of 0.8-1.2 nm, and a single-layer ratio of 99%.

[0064] The nano-titanium dioxide suspension was purchased from Hangzhou Hengna New Materials Co., Ltd. It is a rutile titanium dioxide ethanol-water suspension with a solid content of 30 wt% and a nano-titanium dioxide particle size of 15-30 nm.

[0065] The polyester resin powder was purchased from Zhejiang Guanghua Science & Technology Co., Ltd., model number GH-6609;

[0066] The curing agent was triglycidyl isocyanurate (TGIC), purchased from Hunan Yunke Chemical Co., Ltd.

[0067] The wetting and leveling agent is an organosilicon-based wetting and leveling agent, purchased from Beijing Maier Chemical Technology Co., Ltd., model number HY-5057.

[0068] Example 1

[0069] Take 5g of graphene oxide into a three-necked flask, add 300mL of ethanol, and stir to disperse thoroughly; then add 30g of nano-titanium dioxide suspension and 30g of KH570, stir and mix for 1h, raise the temperature to 70℃ and modify the system under reflux for 2h; after the modification treatment is completed, cool naturally to room temperature, centrifuge and then vacuum dry the obtained solid material at 35℃ to obtain graphene oxide-nano-titanium dioxide composite material.

[0070] By weight, take 78.5 parts of polyester resin powder, add 7 parts of graphene oxide-nano titanium dioxide composite material, 4 parts of curing agent (TGIC), 9 parts of barium sulfate, 0.5 parts of benzoin and 0.5 parts of wetting and leveling agent (HY-5057), and mix thoroughly to obtain a composite resin powder with high thermal conductivity and high fluidity.

[0071] The molding die is preheated to 110°C. The composite resin powder is electrostatically sprayed onto the inner surface of the die (100 μm thickness). The die is kept at this temperature for 25 seconds to allow the composite resin powder to melt and wet the die surface. While the die is being kept at this temperature, the glass fiber reinforced polyester composite material is filled into the die cavity. After the die is kept at this temperature, the die is heated to 150°C and cured for 30 minutes. After curing, the die is demolded to obtain an integrally molded surface-coated composite material, which includes the glass fiber reinforced polyester composite material and a coating formed by the composite resin powder on the surface of the glass fiber reinforced polyester composite material.

[0072] Example 2

[0073] Take 5g of graphene oxide into a three-necked flask, add 300mL of ethanol, and stir to disperse thoroughly; then add 50g of nano-titanium dioxide suspension and 40g of KH570, stir and mix for 1h, raise the temperature to 60℃ and modify the system under reflux for 2h; after the modification treatment is completed, cool naturally to room temperature, centrifuge and then vacuum dry the obtained solid material at 38℃ to obtain graphene oxide-nano-titanium dioxide composite material.

[0074] Composite resin powder was prepared using the graphene oxide-nano titanium dioxide composite material according to the method of Example 1, and then an integrally molded surface-coated composite material was prepared using the composite resin powder according to the method of Example 1.

[0075] Example 3

[0076] Graphene oxide-nano titanium dioxide composite material was prepared according to the method in Example 1.

[0077] By weight, take 74.5 parts of polyester resin powder, add 12 parts of graphene oxide-nano titanium dioxide composite material, 4 parts of curing agent (TGIC), 8 parts of barium sulfate, 0.5 parts of benzoin and 0.5 parts of wetting and leveling agent (HY-5057), and mix thoroughly to obtain a composite resin powder with high thermal conductivity and high fluidity.

[0078] An integrally molded surface-coated composite material was prepared using the composite resin powder according to the method of Example 1.

[0079] Example 4

[0080] Take 40g of nano-titanium dioxide suspension, add 25g of KH570, and then add ethanol to make the total volume of the liquid 100mL. Stir and mix for 1h, and heat to 60℃ to modify the system under reflux for 100min. After the modification treatment is completed, cool naturally to room temperature, centrifuge and then vacuum dry the obtained solid material at 35℃ to obtain modified nano-titanium dioxide particles.

[0081] Take 5g of graphene oxide into a three-necked flask, add 300mL of ethanol, stir and disperse thoroughly, then add 40g of KH570 and 10g of modified nano-titanium dioxide particles, stir and mix for 1h, heat to 60℃ and modify the system under reflux for 2h; after the modification treatment is completed, cool naturally to room temperature, centrifuge and then vacuum dry the obtained solid material at 40℃ to obtain graphene oxide-nano-titanium dioxide composite material.

[0082] Composite resin powder was prepared using the graphene oxide-nano titanium dioxide composite material according to the method of Example 1, and then an integrally molded surface-coated composite material was prepared using the composite resin powder according to the method of Example 1.

[0083] Example 5

[0084] Take 40g of nano-titanium dioxide suspension, add 25g of KH570, and then add ethanol to make the total volume of the liquid 100mL. Stir and mix for 1h, and heat to 60℃ to modify the system under reflux for 100min. After the modification treatment is completed, cool naturally to room temperature, centrifuge and then vacuum dry the obtained solid material at 35℃ to obtain modified nano-titanium dioxide particles.

[0085] Take 5g of graphene oxide into a three-necked flask, add 300mL of ethanol, stir and disperse thoroughly, then add 40g of KH570, stir and mix for 1h, raise the temperature to 60℃ and modify the system under reflux conditions for 2h; after the modification treatment is completed, cool naturally to room temperature, centrifuge and then vacuum dry the obtained solid material at 40℃ to obtain modified graphene oxide.

[0086] By weight, take 78.5 parts of polyester resin powder, add 7 parts of graphene oxide-nano titanium dioxide composite material (specifically a mixture of 2.5 parts of modified graphene oxide and 4.5 parts of modified nano titanium dioxide particles), 4 parts of curing agent (TGIC), 9 parts of barium sulfate, 0.5 parts of benzoin and 0.5 parts of wetting and leveling agent (HY-5057), mix thoroughly and evenly to obtain a composite resin powder with high thermal conductivity and high fluidity.

[0087] An integrally molded surface-coated composite material was prepared using the composite resin powder according to the method of Example 1.

[0088] Comparative Example 1

[0089] Take 75.5 parts by weight of polyester resin powder, add 10 parts of nano titanium dioxide, 4 parts of curing agent (TGIC), 9 parts of barium sulfate, 0.5 parts of benzoin and 0.5 parts of wetting and leveling agent (HY-5057), and mix thoroughly to obtain composite resin powder.

[0090] The molding die is preheated to 120°C. Composite resin powder is electrostatically sprayed onto the upper surface of the die (100μm thickness). The die is kept at this temperature for 35 seconds to allow the composite resin powder to melt and wet the die surface. While the die is being kept at this temperature, glass fiber reinforced polyester composite material is filled into the die cavity. After the die is kept at this temperature, the die is heated to 150°C and cured for 35 minutes. After curing, the die is demolded to obtain an integrally molded surface-coated composite material, which includes a composite material matrix and a coating formed by composite resin powder covering the surface of the composite material matrix.

[0091] Comparative Example 2

[0092] The integrally molded surface-coated composite material was prepared according to the method of Example 1, except that graphene oxide was omitted.

[0093] Test Example 1

[0094] The wear resistance (scratch resistance), weather resistance, and solvent resistance of the coatings in the integrally molded surface-coated composite materials prepared in Examples 1-5 and Comparative Examples 1-2 were tested using the following methods:

[0095] Abrasion resistance was tested according to GB / T 1768-2006 "Determination of Abrasion Resistance of Paints and Varnishes", using the rotating rubber grinding wheel method to determine the wear quality after 500 revolutions;

[0096] Weather resistance was tested according to GB / T 1865-2009 "Paints and Varnishes - Artificial Climate and Artificial Radiation Exposure - Filtered Xenon Arc Radiation". The test was conducted using a daylight filter xenon lamp and wetting cycle B.

[0097] Solvent resistance was tested according to GB / T 9274-1988 "Determination of resistance to liquid media for paints and varnishes", and the test was conducted by immersion method.

[0098] Table 1 shows the performance test results of the coatings in the integrally molded surface-coated composite materials prepared in Examples 1-5 and Comparative Examples 1-2. As can be seen from Table 1, adding graphene oxide and nano-titanium dioxide to the solid gel coat can effectively improve the weather resistance and solvent resistance of the coating. Furthermore, the synergistic modification of nano-titanium dioxide and graphene oxide allows the nano-titanium dioxide particles to embed into the interlayer voids of the graphene oxide structure, achieving not only perfect dispersion but also synergistic effects to fully utilize its lubricity and wear resistance. Specifically, compared to Comparative Examples 1-2, in Examples 1-3, a silane coupling agent was used to modify graphene oxide and nano-titanium dioxide in the same system. In Example 4, the prepared modified graphene oxide-nano titanium dioxide composite material was first modified with a silane coupling agent, and then graphene oxide and the obtained modified nano titanium dioxide were jointly modified in the same system. In Example 5, graphene oxide and nano titanium dioxide were modified separately with a silane coupling agent. Based on this, the prepared modified graphene oxide-nano titanium dioxide composite material was added to the solid gel coat. The properties of the coating were lower than those of Example 1, but still better than those of Comparative Examples 1-2. Moreover, the graphene oxide-nano titanium dioxide composite material should not be added in excess, as excessive amounts of graphene oxide-nano titanium dioxide composite material can easily cause agglomeration, thus affecting the actual performance of the solid gel coat.

[0099] Table 1. Performance test results of the coatings in the integrally molded surface-coated composite materials prepared in Examples 1-5 and Comparative Examples 1-2.

[0100]

[0101] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a surface-coated composite material, characterized in that, Includes the following steps: A solid gel coat is applied to the inner surface of a preheated molding die. The composite material matrix is ​​then placed inside the cavity of the molding die and molded and cured, resulting in a coating formed by the solid gel coat on the surface of the composite material matrix, thus obtaining the surface-coated composite material. The solid gel coat, by weight, is prepared from the following components: 78.5 parts polyester resin, 7 parts graphene oxide-nano titanium dioxide composite material, 9 parts barium sulfate, 4 parts curing agent, 0.5 parts benzoin, and 0.5 parts wetting and leveling agent. The graphene-nano titanium dioxide composite material is obtained by modifying graphene oxide and nano titanium dioxide with a silane coupling agent; the mass ratio of graphene oxide, nano titanium dioxide and silane coupling agent is 5:9:30; the graphene oxide-nano titanium dioxide composite material is prepared by method (1); the method (1) includes the following steps: mixing graphene oxide, nano titanium dioxide suspension, silane coupling agent and ethanol, performing a first modification treatment, and obtaining the graphene oxide-nano titanium dioxide composite material.

2. The method for preparing the surface-coated composite material according to claim 1, characterized in that, The graphene oxide is a single-layer graphene oxide with a sheet diameter of 0.5~5μm and a single-layer thickness of 0.8~1.2nm; the nano-titanium dioxide is rutile titanium dioxide with a particle size of 15~30nm.

3. The method for preparing the surface-coated composite material according to claim 1, characterized in that, The silane coupling agent includes one or more of KH550, KH560 and KH570.

4. The method for preparing the surface-coated composite material according to any one of claims 1 to 3, characterized in that, The method for preparing the solid gelcoat includes the following steps: mixing the raw materials for preparing the solid gelcoat to obtain the solid gelcoat.

5. The method for preparing the surface-coated composite material according to claim 1, characterized in that, The composite material matrix is ​​a fiber-reinforced resin material; the resin material in the fiber-reinforced resin material includes epoxy resin, polyester resin, polyurethane resin or acrylic resin, and the reinforcing fibers in the fiber-reinforced resin material include glass fiber, carbon fiber, basalt fiber, hemp fiber, bamboo fiber or wood fiber.

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