Abstract: A prepreg which is suitable for producing a fiber-reinforced composite material in a short period of time without using an autoclave, can produce a fiber-reinforced composite material in which the occurrence of voids is suppressed and excellent impact resistance is achieved, and has excellent handling properties; and a fiber-reinforced composite material using the prepreg. This prepreg is a prepreg in which a reinforcing fiber [A] arranged in layers is partially impregnated with an epoxy resin composition containing an epoxy resin [B] and a curing agent [C], wherein the impregnation rate ? is 30-95%, and a thermoplastic resin [D] insoluble in the epoxy resin [B] is unevenly distributed on both surfaces of the prepreg. In addition, in the layers of the reinforcing fiber [A], epoxy resin composition-unimpregnated portions are localized on one surface of the prepreg, and the localization parameter a, which defines the degree of localization, is in the range of 0.10<?<0.45.

Abstract: A prepreg which is suitable for producing a fiber-reinforced composite material in a short period of time without using an autoclave, can produce a fiber-reinforced composite material in which the occurrence of voids is suppressed and excellent impact resistance is achieved, and has excellent handling properties; and a fiber-reinforced composite material using the prepreg. This prepreg is a prepreg in which a reinforcing fiber [A] arranged in layers is partially impregnated with an epoxy resin composition containing an epoxy resin [B] and a curing agent [C], wherein the impregnation rate ? is 30-95%, and a thermoplastic resin [D] insoluble in the epoxy resin [B] is unevenly distributed on both surfaces of the prepreg. In addition, in the layers of the reinforcing fiber [A], epoxy resin composition-unimpregnated portions are localized on one surface of the prepreg, and the localization parameter a, which defines the degree of localization, is in the range of 0.10<?<0.45.

Abstract: The objective of the present invention is to provide a prepreg and a fiber reinforced composite material using this prepreg. This prepreg has good handleability, is suitable for producing a reinforced composite material in a short-time and without using an autoclave, and is capable of yielding a fiber reinforced composite material exhibiting excellent impact resistance, wherein the occurrence of voids has been suppressed. To attain the objective, this prepreg comprises a reinforced fiber [A] that is layered and partially impregnated with an epoxy resin composition containing an epoxy resin [B] and a hardener [C], the impregnation rate ? being 30 to 95%. In this prepreg, a thermoplastic resin [D] insoluble in the epoxy resin [B] is distributed unevenly over a surface on one side of the prepreg, and a portion not impregnated with the epoxy resin composition is localized in the layer of the reinforced fiber [A] on the side where the thermoplastic resin [D] is distributed unevenly.

Abstract: An intermediate base material has high handleability and shape conformity to complicated shapes and serves to perform high-yield production, even by low pressure molding, of fiber reinforced plastic material that do not suffer from significant generation of molding defects, such as creases and voids, that can cause a decrease in strength and that has good mechanical characteristics, decreased variations therein, and high dimensional stability. The prepreg includes a layer containing reinforcement fibers impregnated with a resin composition and the impregnation rate with the resin composition in the prepreg is in a predetermined range. It is characterized by being an incised prepreg having a plurality of incisions, being at least partly formed of reinforcement fibers with a predetermined fiber length, and having a reinforcement fiber content by volume Vf in a predetermined range.

Abstract: A process is capable of producing a high-quality fiber-reinforced plastic with good yield in a short molding cycle time despite being atmospheric pressure molding. The process characterized uses local contact heating to give different temperature conditions to produce a fiber-reinforced plastic by atmospheric pressure molding from a fiber-reinforced material which contains a reinforcing fiber impregnated with a thermosetting resin composition.

Abstract: The objective of the present invention is to provide a prepreg and a fiber reinforced composite material using this prepreg. This prepreg has good handleability, is suitable for producing a reinforced composite material in a short-time and without using an autoclave, and is capable of yielding a fiber reinforced composite material exhibiting excellent impact resistance, wherein the occurrence of voids has been suppressed. To attain the objective, this prepreg comprises a reinforced fiber [A] that is layered and partially impregnated with an epoxy resin composition containing an epoxy resin [B] and a hardener [C], the impregnation rate ? being 30 to 95%. In this prepreg, a thermoplastic resin [D] insoluble in the epoxy resin [B] is distributed unevenly over a surface on one side of the prepreg, and a portion not impregnated with the epoxy resin composition is localized in the layer of the reinforced fiber [A] on the side where the thermoplastic resin [D] is distributed unevenly.

Abstract: A prepreg, including: a fiber layer containing unidirectionally arranged discontinuous carbon fibers and a thermosetting resin; and a resin layer existing on at least one side of said fiber layer and containing a thermosetting resin and a thermoplastic resin; in which said prepreg contains carbon fibers having an areal weight of fibers of 120 to 300 g/m2, and has a mass fraction of resin of 25 to 50% with respect to the whole mass of said prepreg; and in which a temperature at which a coefficient of interlayer friction is 0.05 or less is in a temperature range of from 40 to 80° C., the interlayer friction being caused at the contact interface between layers of said prepreg when the middle one of three layers that are each made of said prepreg and laid up is pulled out, said coefficient of interlayer friction being measured at 10° C. intervals in a temperature range of from 40 to 80° C. under conditions including a pulling speed of 0.2 mm/min, a perpendicular stress of 0.08 MPa, and a pulling length of 1 mm.

Abstract: An intermediate base material has high handleability and shape conformity to complicated shapes and serves to perform high-yield production, even by low pressure molding, of fiber reinforced plastic material that do not suffer from significant generation of molding defects, such as creases and voids, that can cause a decrease in strength and that has good mechanical characteristics, decreased variations therein, and high dimensional stability. The prepreg includes a layer containing reinforcement fibers impregnated with a resin composition and the impregnation rate with the resin composition in the prepreg is in a predetermined range. It is characterized by being an incised prepreg having a plurality of incisions, being at least partly formed of reinforcement fibers with a predetermined fiber length, and having a reinforcement fiber content by volume Vf in a predetermined range.

Abstract: A process is capable of producing a high-quality fiber-reinforced plastic with good yield in a short molding cycle time despite being atmospheric pressure molding. The process characterized uses local contact heating to give different temperature conditions to produce a fiber-reinforced plastic by atmospheric pressure molding from a fiber-reinforced material which contains a reinforcing fiber impregnated with a thermosetting resin composition.

Abstract: A laminated base material includes a lamination and integration of prepreg base materials each of which includes many reinforcing fibers arranged substantially in one direction and a matrix resin adhered to the reinforcing fibers, wherein at least one of the laminated prepreg base materials is formed with a prepreg base material having, throughout its whole surface, many incisions each extending in a direction crossing the reinforcing fibers, substantially all of the reinforcing fibers divided by incisions, and wherein a length L of each of reinforcing fiber segments formed by the incisions is 10 to 100 mm, a thickness H of the prepreg base material is 30 to 300 ?m, and a fiber volume content Vf of the reinforcing fibers is 45 to 65% and arranging directions of the reinforcing fibers between one and another laminated prepreg base materials have at least two directions different each other.

Abstract: A prepreg base material includes reinforcing fibers arranged substantially in one direction and a matrix resin between the reinforcing fibers, wherein the prepreg base material has substantially throughout its entire surface incisions, each incision extending in a direction substantially crossing the reinforcing fibers, wherein substantially all of the reinforcing fibers are divided by the incisions, a length (L) of each of reinforcing fiber segments formed by the incisions is in the range of 10 to 100 mm, a thickness H of the prepreg base material is in the range of 30 to 300 ?m, and a fiber volume content by Vf of the reinforcing fibers is in the range of 45 to 65%.

Abstract: A chopped fiber bundle includes a large number of unidirectionally arranged reinforced fibers. The length of each of the reinforced fibers is in the range of 5 to 100 mm. The chopped fiber bundle has a transition segment in which the number of the reinforced fibers increases toward the central part of the chopped fiber bundle in the aligned direction of the reinforced fibers with both ends in the aligned of the reinforced fibers in the chopped fiber bundle being a starting point. The level of a change in total sectional area of the large number of reinforced fibers is not more than 0.05 mm2 per mm in the aligned direction of the reinforced fibers over the whole area in the longitudinal direction of the chopped fiber bundle.

Abstract: A chopped fiber bundle includes a large number of unidirectionally arranged reinforced fibers. The length of each of the reinforced fibers is in the range of 5 to 100 mm. The chopped fiber bundle has a transition segment in which the number of the reinforced fibers increases toward the central part of the chopped fiber bundle in the aligned direction of the reinforced fibers with both ends in the aligned of the reinforced fibers in the chopped fiber bundle being a starting point. The level of a change in total sectional area of the large number of reinforced fibers is not more than 0.05 mm2 per mm in the aligned direction of the reinforced fibers over the whole area in the longitudinal direction of the chopped fiber bundle.

Abstract: A prepreg base material includes reinforcing fibers arranged substantially in one direction and a matrix resin between the reinforcing fibers, wherein the prepreg base material has substantially throughout its entire surface incisions, each incision extending in a direction substantially crossing the reinforcing fibers, wherein substantially all of the reinforcing fibers are divided by the incisions, a length (L) of each of reinforcing fiber segments formed by the incisions is in the range of 10 to 100 mm, a thickness H of the prepreg base material is in the range of 30 to 300 ?m, and a fiber volume content by Vf of the reinforcing fibers is in the range of 45 to 65%.