Isotropic fiber-reinforced thermoplastic resin sheet, and process for production and molded plate thereof
An isotropic fiber-reinforced thermoplastic resin sheet wherein a chopped strand prepreg comprising a thermoplastic resin and a reinforcing fiber is layered so that the fiber orientation is random, the prepreg having a fiber volume fraction (Vf) of 20% to 50%, a length in the fiber axis direction of 15 to 45 mm, and a thickness of no greater than 0.13 mm, and the layered material is molded into sheet form by heating and pressing, and a molded plate obtained from the isotropic fiber-reinforced thermoplastic resin sheet. Even if the volume fraction of the reinforcing fiber is relatively low, a fiber-reinforced thermoplastic resin sheet and a molded plate that are excellent in terms of mechanical properties and their uniformity can be obtained.
1. A molded plate in which one fiber-reinforced thermoplastic resin sheet or a layered plurality of fiber-reinforced thermoplastic resin sheets are integrally molded, the molded plate comprising:
an isotropic fiber-reinforced thermoplastic resin sheet comprising a layered material molded into sheet form by heating and pressing, the layered material being a chopped strand prepreg, comprising a thermoplastic resin as a matrix and a reinforcing fiber, that is layered so that the fiber orientation is random, the prepreg having a fiber volume fraction of 20% to 50%, a length in the fiber axis direction of 15 to 45 mm, and a thickness of no greater than 0.13 mm, and
the theoretical number of layers of the molded plate satisfying the following expression:
theoretical number of layers=(thickness of molded plate)/(thickness of one prepreg)≧10.
2. The molded plate according to claim 1 , wherein the reinforcing fiber is carbon fiber.
3. The molded plate according to claim 1 , wherein CV values of the molded plate for flexural strength and flexural modulus of elasticity measured in accordance with JIS K 7017 are no greater than 10.
4. The molded plate according to claim 1 , wherein the prepreg has a thickness of 0.05-0.10 mm.
5. The molded plate according to claim 1 , wherein the theoretical number of layers is equal to or greater than 15.
6. The molded plate according to claim 1 , wherein the prepreg has a width of 10 to 30 mm with respect to the longitudinal direction.