Preparation method of epoxy resin prepreg with release coating

Abstract

The present invention discloses a method for preparing an epoxy resin prepreg with a release coating, and the specific steps are as follows: infiltrating an organosilicon solution on the adhesive surface of a release paper tape and heating and curing, then heating and dissolving the prepreg and coating it on the release paper, and after the amino group in the coating reacts with the resin, the coating is evenly attached to the surface of the prepreg. When the prepreg is laid, the release paper is peeled off, and the prepreg with the release coating is placed on the outermost layer of the product, close to the mold, so as to facilitate the demoulding of the product from the mold. The coating has good lubricity and stability, fast curing speed, strong adhesion, and good demoulding properties. Compared with ordinary external release agents and internal release agents, it can effectively improve production efficiency, reduce production costs, and ensure the surface uniformity and performance stability of the product.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, and in particular to a method for preparing an epoxy resin prepreg with a release coating. Background Art

[0002] Composite materials are a kind of multiphase solid material composed of two or more substances with different physical and chemical properties. Although the component materials of composite materials maintain their relative independence, the performance of composite materials is not a simple addition of the performance of component materials, but the "strengths and weaknesses" and "cooperation" between the components, which greatly make up for the shortcomings of a single material and produce new properties that a single material does not have. Fiber-reinforced resin-based composite materials are a kind of high-performance composite materials with fiber as reinforcement material and resin as matrix. They not only have low density, but also have high specific strength, large modulus, good corrosion resistance, and have become an irreplaceable important material in the fields of aerospace, energy equipment, transportation, sports and leisure. Prepreg is a combination of reinforcement material and resin matrix made by impregnating continuous fibers or fabrics in resin matrix under precisely controlled conditions. It is an intermediate material for manufacturing fiber-reinforced composite materials. In the formula of epoxy resin prepreg, in addition to epoxy resin matrix and reinforcing materials (carbon fiber, glass fiber, etc.), it also includes additives such as curing agent, curing accelerator, and release agent. Among them, the release agent is a type of auxiliary agent added to improve the processability and demolding properties of the resin during the molding process. According to the compatibility and function with the resin, it can be divided into internal release agent and external release agent. However, the demolding effect of these two release agents is not ideal, which will cause certain damage to the surface uniformity and mechanical properties of the material. The cost of internal release agent is relatively high, and the external release agent has high requirements for manual operation, which affects the production efficiency and production cost of the material. Therefore, it is very important to develop a suitable demolding method to improve production efficiency, reduce costs and ensure product quality. Summary of the invention

[0003] Technical problem to be solved: The technical problem to be solved by the present invention is to provide a method for preparing an epoxy resin prepreg with a release coating.

[0004] Technical solution: A method for preparing an epoxy resin prepreg with a release coating, comprising the following steps: S1. Add hydroxy silicone oil, aminosilane and catalyst to the hydrocarbon solution in sequence and stir evenly to obtain an organosilicon solution; S2. The adhesive surface of the release paper is contacted with the silicone solution and fully infiltrated, and the solvent is evaporated and the silicone is cured by heating and ventilation to obtain a release paper with a cured coating; S3. Heat the epoxy resin until it dissolves, mix it with the fiber, and evenly apply it on the release paper with the curing coating by rolling, and leave it until the reaction between the coating and the resin is complete to obtain the epoxy resin prepreg with the release coating. Preferably, in step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, aminosilane and catalyst is 100:1.5-4.5:0.3-1:0.015-0.25. Preferably, the hydrocarbon solvent in step S1 includes any one or more of 120# solvent, D30 solvent, and D60 solvent. Preferably, the hydroxy silicone oil in step S1 includes any one or more of hydroxy silicone oils with viscosities of 100 cs, 1000 cs, and 10000 cs. Preferably, the aminosilane in step S1 includes any one or more of 3-aminopropyltriethoxysilane, aminoethylaminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and aminoethylaminopropyltrimethoxysilane. Preferably, the catalyst in step S1 includes any one of dibutyltin dilaurate or chelated tin. Preferably, the heating and curing temperature in step S2 is 65-75°C. Preferably, the epoxy resin is heated and dissolved at a temperature of 75-85°C in step S3. Beneficial effects: Compared with the prior art, the present invention has the following characteristics: The preparation method of the epoxy resin prepreg with a release coating of the present invention is to soak the adhesive surface of the release paper with an organic solvent and heat and cure it, and then coat the resin on the release paper so that the amino group in the cured layer reacts with the resin to produce a release coating. When the prepreg is laid, the prepreg with the release coating is placed on the outermost layer of the product close to the mold to facilitate product demolding. When manufacturing products in the rubber and plastic manufacturing industry, in order to facilitate demoulding, improve efficiency, extend the life of the mold, and make the product surface smooth, qualified in size, and reduce waste, a release agent is required. The commonly used release agents in the current market include internal release agents and external release agents. Among them, the internal release agent is a type of substance added to the molding material. During the molding process, it migrates to the surface of the product, thereby playing a role in isolating from the mold, but the internal release agent has poor demoulding performance and usually needs to be used in conjunction with an external release agent. It also has an impact on the mechanical properties of the material and is costly; the external release agent is sprayed on the mold surface to prevent the product from bonding to the mold, but the coating process is inefficient and requires high manual operation, and it is easy to produce fouling in the mold, which is not conducive to the improvement of overall production efficiency. The present invention cures the silicone coating on the adhesive surface of the release paper, and coats the prepreg thereon, so that the resin reacts with the amino group on the coating and combines them together. When the release paper is peeled off from the prepreg, the coating will remain on the prepreg. Silicone has low viscosity and low surface tension. As a coating, it can act as a lubricant between the mold and the prepreg, thereby assisting in demoulding. Silicone is stable and not easily affected by oxidants or high temperatures, thus maintaining the stability of material properties. Compared with the prior art, the present invention has the following advantages and positive effects: The present invention reduces the use of external mold release agents, reduces labor, and reduces auxiliary material and labor costs. The present invention avoids using an internal mold release agent, thereby avoiding the influence of the internal mold release agent on product performance and significantly reducing costs. The present invention reduces the process of applying a release agent, reduces mold contamination, and significantly improves production efficiency. DETAILED DESCRIPTION In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. Specific preferred examples are as follows: Embodiment 1: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 10000cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:0.5:0.04. Embodiment 2: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:0.5:0.04. Embodiment 3: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 100 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:0.5:0.04. Embodiment 4: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000cs, aminoethylaminopropyl triethoxysilane and dibutyltin silicate catalyst were sequentially added to 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, aminoethylaminopropyltriethoxysilane and catalyst is 100:2:0.5:0.04. Embodiment 5: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, 3-aminopropyl trimethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltrimethoxysilane and catalyst is 100:2:0.5:0.04. Embodiment 6: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, aminoethylaminopropyl trimethoxysilane and dibutyltin silicate catalyst were sequentially added to 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, aminoethylaminopropyltrimethoxysilane and catalyst is 100:2:0.5:0.04. Embodiment 7: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:0.5:0.1. Embodiment 8: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000cs, 3-aminopropyl triethoxysilane and catalyst chelated tin were successively added to 120# solvent and stirred to obtain an organosilicon solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:0.5:0.04. Embodiment 9: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil having a viscosity of 1000 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to the D30 solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:0.5:0.04. Embodiment 10: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to the D60 solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:0.5:0.04. In order to further illustrate the technical effect of the present invention, the present invention also provides a comparative example, which is as follows: Comparative Example 1: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:1:0.5:0.04. Comparative Example 2: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:5:0.5:0.04. Comparative Example 3: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:0.2:0.04. Comparative Example 4: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:1.2:0.04. Comparative Example 5: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:0.5:0.01. Comparative Example 6: A method for preparing an epoxy resin prepreg with a release coating comprises the following steps: S1. Hydroxy silicone oil with a viscosity of 1000 cs, 3-aminopropyl triethoxysilane and a catalyst dibutyltin silicate were sequentially added to a 120# solvent and stirred to obtain a silicone solution; S2. The adhesive surface of the release paper is brought into contact with the silicone solution and fully infiltrated, heated to 70°C and ventilated to evaporate the solvent and cure the silicone to obtain a release paper with a cured coating; S3. The epoxy resin is heated to 80°C to dissolve, mixed with the fiber, and evenly coated on the release paper with the cured coating by rolling, and left to react with the resin to obtain an epoxy resin prepreg with a release coating; In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, 3-aminopropyltriethoxysilane and catalyst is 100:2:0.5:0.3. The coating performance was evaluated by testing the curing speed, demoulding property and coating adhesion of each embodiment and comparative example, and the test results are shown in the table. The coating adhesion was tested by the scribing method, where a regular grid was drawn on the coating surface, and then the coating was pasted with tape and quickly torn off. The coating peeling in the scribing area was graded according to GB / T 9286-1998: Grade 0 means that the edge of the scribing area is completely smooth, with no or little coating peeling, indicating that the coating adhesion is very good; Grade 1 means that the coating peels off less than 5% in the scribing area, indicating that the coating adhesion is ideal; Grade 2 means that the coating peels off 5-15% in the scribing area, indicating that the adhesion has decreased, but is within the qualified range; Grade 3 means that the coating peels off 15-35% in the scribing area, indicating that the adhesion performance is medium; Grade 4 means that the coating peels off more than 35%, and the adhesion is seriously insufficient. In summary, the coatings of the embodiments of the present invention have good curing speed, good demoulding property and strong coating adhesion; in the comparative examples, due to the inappropriate addition ratio of hydroxy silicone oil, aminosilane and catalyst, the demoulding performance of comparative examples 1 and 4 is significantly reduced, the film thickness of comparative example 2 is easy to fall off, the curing speed of comparative example 5 is slow, and comparative example 3 is not cured directly, and the adhesion of comparative example 6 is poor. The addition ratio of hydroxy silicone oil, aminosilane and catalyst in the present invention has an important influence on the demoulding property and coating adhesion.

Claims

1. A method for preparing an epoxy resin prepreg with a release coating, characterized in that: The following steps are involved: S1. Add hydroxy silicone oil, aminosilane and catalyst to the hydrocarbon solution in sequence and stir evenly to obtain an organosilicon solution; S2. The adhesive surface of the release paper is contacted with the silicone solution and fully infiltrated, and the solvent is evaporated and the silicone is cured by heating and ventilation to obtain a release paper with a cured coating; S3. Heat the epoxy resin until it dissolves, mix it with the fiber, and evenly apply it on the release paper with the curing coating by rolling, and leave it until the reaction between the coating and the resin is complete to obtain the epoxy resin prepreg with the release coating.

2. The method for preparing an epoxy resin prepreg with a release coating according to claim 1, characterized in that: In step S1, the ratio of hydrocarbon solution, hydroxy silicone oil, aminosilane and catalyst is 100: 1.5-4.5: 0.3-1: 0.015-0.

25.

3. The method for preparing an epoxy resin prepreg with a release coating according to claim 1, characterized in that: The hydrocarbon solvent in step S1 includes any one or more of 120# solvent, D30 solvent, and D60 solvent.

4. The method for preparing an epoxy resin prepreg with a release coating according to claim 1, characterized in that: The hydroxy silicone oil in step S1 includes any one or more of hydroxy silicone oils having viscosities of 100 cs, 1000 cs and 10000 cs.

5. The method for preparing an epoxy resin prepreg with a release coating according to claim 1, characterized in that: The aminosilane in step S1 includes any one or more of 3-aminopropyltriethoxysilane, aminoethylaminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and aminoethylaminopropyltrimethoxysilane.

6. The method for preparing an epoxy resin prepreg with a release coating according to claim 1, characterized in that: The catalyst in step S1 includes any one of dibutyltin diosilicate or chelated tin.

7. The method for preparing an epoxy resin prepreg with a release coating according to claim 1, characterized in that: The heating curing temperature in step S2 is 65-75°C.

8. The method for preparing an epoxy resin prepreg with a release coating according to claim 1, characterized in that: The epoxy resin is heated and dissolved at a temperature of 75 to 85°C in step S3.

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