Epoxy vinyl ester resin can be designed to meet the requirements of sheet molding process, that is, thickened vinyl ester resin (such as FUCHEM893). According to experts, this is a resin that allows the curing process to be carried out in stages. It is used in prepregs or sheet molding compounds to allow the curing reaction to proceed to the first stage before hot press molding. The resin used must have chemical thickening properties, and can retain the unsaturation in the molecule, so that it can be crosslinked and cured during molding. To this end, an acidic functional group was introduced on the vinyl ester molecule for the thickening reaction. This kind of resin has better permeability to glass fiber than polyester resin, and has better fluidity, so that the pressure can be reduced during hot pressing, and the reaction speed is very fast in the second stage. This epoxy vinyl ester resin sheet molding compound can be used to mold structural parts, especially structural parts on automobiles to reduce weight. Adding low-shrinkage additives of thermoplastic materials can improve surface properties and low-shrinkage. Vinyl ester resin SMC/BMC is mainly used in automobiles, especially for manufacturing high-strength structural parts. Among these parts, physical and mechanical properties such as strength and toughness are more important, and appearance requirements are relatively low. In addition, it is also used in corrosion-resistant or heat-resistant environments. In the past, most of the SMC/BMC resins used in vehicle parts used glass fiber as the reinforcing material.
With the increase in people's requirements for lightweight, low fuel consumption, high safety, and environmental protection, high-strength fiber composite materials, especially carbon fiber composite materials (CFRP), due to their small mass, high strength, high rigidity and good resistance Creep and corrosion resistance make it a promising lightweight material for automobiles. The application of carbon fiber composite materials in automobiles has been synchronously enhanced. According to experts, the United States is doing its best in this regard. Carbon fiber reinforced composite materials have the advantages of light weight and high mechanical properties, especially excellent flexural modulus (stiffness). In order to minimize the low weight of SMC and high-strength vinyl ester trees, carbon fiber reinforced materials are traditionally made of epoxy resin without fillers. Due to the use of hand lay-up molding or resin transfer molding process, this material is usually used to manufacture small batches of aerospace parts, racing cars and other special products. The high cost of epoxy resin, the high price of carbon fiber and the labor-intensive molding process limit the large-scale industrial application of carbon fiber composite materials. To this end, the industry at home and abroad is committed to the development of large-scale, low-cost carbon fiber-reinforced composite materials. In fact, in the past 20 years, the world has created two records of doubling output in 6 years. The price of carbon fiber has fallen and its application has been promoted.
If we further seize the opportunity to accelerate development, carbon fiber composite materials have a very objective possibility to achieve large-scale automotive applications. The application of carbon fiber reinforced SMC (CF-SMC) in automobile parts can significantly reduce the weight, and the weight of attachments, bearing members, fasteners and other accessories can also be reduced. Auto parts usually bear a variety of loads. If they play a role of 50% tensile and 50% bending strength, it means that the wall thickness of CF-SMC parts can be reduced by 40% compared to traditional SMC. Therefore, based on rigidity such as Replacing standard SMC with CF-SMC should reduce weight by about 55%. According to experts, recently European companies have introduced vinyl ester CF-SM for semi-structured and structural automotive parts that are not Class A surfaces. Raw materials and molding equipment are provided by the German company Ludwig-shafcn. The CF-SMC produced provides excellent manufacturability, light weight and high mechanical properties. The components are AtlacXP810 vinyl ester resin and dispersed large tow (48K) carbon fiber reinforced material. CF-SMC shows good fluidity and uniform fiber distribution. The mold closing speed and curing time can refer to the standard SMC. The mechanical properties and specific gravity of the molded parts are significantly better than the equivalent glass fiber reinforced SMC