Carbon fiber fabric and prepreg play a great role in promoting the whole carbon fiber industry It is imperative to develop carbon fiber prepreg, and it is also an effective means to extend the industrial chain and improve the added value of carbon fiber. According to the development experience of Yixing Tianniao and Jiangshan science and technology, carbon fiber prepreg and fabric are new high-performance composite materials, basic materials of national defense and military enterprises, and advanced substitute materials of civil industry in the future.
In recent years, carbon fiber prepreg products have shown a new development trend
- The advantages of carbon fiber prepreg with large tow in the industrial field are highlighted. The surface density of unidirectional carbon fiber prepreg is as high as 600 g / m2, which greatly improves the efficiency of prepreg and subsequent placement process. It is widely used in wind turbine blade and automobile field.
- The prepreg of OOA (out of autoclave) is developing rapidly. This molding process greatly reduces the time and cost of subsequent curing and molding of prepreg. These new prepreg can adopt low-cost vacuum bag pressing method, advanced pultrusion method and hot mold pressing method. Products such as hexply? M 56 of Hexcel, TC 250 of tencate, cycom 532 of Cytec and MTM 44-1 of ACG.
- The appearance of different prepreg products. For short cut prepreg, economical molding process can be adopted, such as Hexcel’s hexmc, de NCATE’s MS series products; semi prepreg does not need to be completely ― wet ‖ fiber in the prepreg process, and complete wetting in the follow-up process, such as hexfit of Hexcel.
- Special prepreg for different applications. For example, in the field of automobile, the requirements for short-time forming of parts are high. In order to meet the subsequent rapid prototyping process, it is necessary to develop a rapid curing prepreg of less than 5 min. products such as Hexcel’s hexply M77 can be cured at 150 ℃ for 2 min. in order to meet the wind turbine blade support beam thick lamination
- Gurit has developed sparpregtm, which can obtain laminates with low porosity without compaction and other exhaust fabrics. In the field of composite mold, various companies have also developed corresponding prepreg products, such as hextool of Hexcel and dform TM of ACG.
- Structural and functional prepreg. Carbon nanotubes or chopped carbon fibers are mixed into the resin, and then the carbon fiber tow or fabric is infiltrated to form a microwave absorbing prepreg.
- Prepreg co cured with other materials. The prepreg can be cured with the resin, molded with SMC, or molded with unidirectional prepreg, fabric prepreg and SMC
In fact, the development of thermoplastic prepreg abroad has been rapid in recent years. For example, the cetex Research Institute of Germany is engaged in the research and development of manufacturing technology and equipment for semi-finished textiles, functional parts and high-performance structures, which is attached to Germany’s kemnitz University of technology. The CE preg? Thermoplastic prepreg of the Institute is a semi-finished fiber composite material formed by the composite of continuous fiber and thermoplastic film.
Compared with thermosetting prepreg, thermoplastic prepreg does not need to be stored and transported in cold storage. The follow-up molding process is efficient and convenient. The material has high toughness and good impact resistance, especially renewable utilization, which is in line with the trend of energy conservation, emission reduction and environmental protection.
But there are four main problems in thermoplastic prepreg
First, the high viscosity of thermoplastic resin leads to the difficulty of infiltration with fiber;
Second, there is no suitable preparation method and equipment with low cost, high efficiency and quality assurance;
Third, the molding temperature of high-performance thermoplastic resin is above 350 ℃, so the molding process of prepreg and its composite products is very difficult;
Fourth, high performance thermoplastic resin is too expensive compared with general thermosetting resin.
At present, thermoplastic prepreg with different resin mass fraction accuracy is obtained by powder spraying, fiber blending, film rolling and other processes, which can meet the needs of various molding applications.