Owing to these characteristics, prepeg is prepared from textile fabrics and nonwovens, drawn out of carbon fiber and thermoplastic fiber made of thermoplastic resin. By cutting the textile fabrics and nonwovens in predetermined dimensional standard and putting them into metal patterns and heating the molten thermoplastic fiber, the molded article, reinforced with carbon fiber, is obtained. Yet, because the characteristic of the carbon fiber of the textile fabrics is the continuous fiber and the carbon fiber is poor in liquidity, it is difficult to make the molded article with deep irregularity. Meanwhile, then nonwoven staple carbon fiber is superior to liquidity, so, the reinforcement effect would be risen in the tip of the molded article with irregularly filled up with the carbon fiber.
Awa Paper and Oji Holdings have produced the nonwovens of carbon fiber and thermoplastic fibers in Japan. The manufacturing process is as such: The staple fiber of the carbon fiber and the thermoplastic fibers are scattered uniformly under water and after sheet making, they are adhered with a binder. The nonwoven is heated in a metallic mold to be dissolved. The thermoplastic fiber and then the molded article of the carbon fiber when dispersed uniformly, could be obtained. Air bubbles do not occur in molded article of laminate nonwovens because of the breathability of the nonwovens. Polypropylene, polyamide polycarbonate and polyetherimide are the resins used for thermoplastic fibers. For polyetherimide fiber to melt, heating of more than 300°C is necessary. When the molded item is in such a high temperature, binder components of the nonwovens can be pyrolytically decomposed and vaporized. Then an air bubble occurs in a molded article. Under these circumstances, the choice of the binder is important to use heat resistant expensive resin for matrix fibers.
Demand for the carbon fiber has been increasing greatly at present. Companies like Toray, Toho Tenax and Mitsubishi Rayon in Japan are among the major carbon fiber manufacturers having the top shares in the world market. Although, Japanese manufacturers are extremely skilled at the technology behind carbon fiber production, when it comes to application technology, they lag Europe and America. Recently, however, a number of businesses have taken part in exploiting Japanese efforts. As various intermediate materials and molded articles have been produced, the nonwovens made of carbon fiber and thermoplastic fibers are among them. In spite of light demand at present, future growth is expected.