Abstract: A carbon fiber composite material includes the material is made of carbon fibers and a thermoplastic resin; the proportion Y, relative to the total weight of carbon fibers, of carbon fiber bundles for which Mn/(Ln×D) is 8.5×10?1 (mg/mm2) or more, is 30?Y<90 (wt %); the average value X of Mn/Ln for the carbon fiber bundles is 1.1×10?2?X?8.1×10?2 (mg/mm); and Y satisfies Y?100X+30, wherein Mn: weight of carbon fiber bundles, Ln: fiber length of carbon fibers, D: fiber diameter of carbon fibers. The carbon fiber composite material combines high flowability and mechanical properties, has few variations in mechanical properties and shows an excellent adaptability of carbon fibers for small parts such as ribs.

Abstract: A method of manufacturing and a device for manufacturing a partial split-fiber fiber bundle and a partial split-fiber fiber bundle obtained are characterized by piercing a fiber splitting means provided with a plurality of protruding parts into a fiber bundle formed from a plurality of single fibers while making the fiber bundle travel along the longitudinal direction thereof and creating a split-fiber processed part, forming entangled parts where single fibers are interlaced at contact parts with the protruding parts in at least one split-fiber processed part, thereafter pulling the fiber splitting means out of the fiber bundle, and after passing through an entanglement accumulation part including the entangled parts, once again piercing the fiber splitting means into the fiber bundle.

Abstract: A reinforcing fiber composite material characterized by comprising discontinuous reinforcing fibers containing discontinuous reinforcing fiber aggregates and a matrix resin, wherein a fan-shaped discontinuous reinforcing fiber aggregate (A) is contained at an amount of 5% by weight or more in the discontinuous reinforcing fibers, and wherein the fan-shaped discontinuous reinforcing fiber aggregate (A) has a fan-like section in which an aspect ratio at least at one end part of a discontinuous reinforcing fiber aggregate (the width of the discontinuous reinforcing fiber aggregate/the thickness of the discontinuous reinforcing fiber aggregate) is 1.5 times or more relative to an aspect ratio at a narrowest part at which the width of the discontinuous reinforcing fiber aggregate is smallest when the discontinuous reinforcing fiber aggregate is projected two-dimensionally.

Abstract: A fiber-reinforced resin molding material includes at least bundled discontinuous reinforcing fiber aggregates and matrix resin, wherein said bundled reinforcing fiber aggregates include both reinforcing fiber aggregates (A) which are formed by cutting continuous reinforcing fiber strands after fiber splitting, in which said strands are completely split into multiple bundles, and reinforcing fiber aggregates (B) having at least unsplit strand sections in which fiber splitting is incomplete, an incision substantially originating from fiber splitting is present at least at one of both end portions of said reinforcing fiber aggregates (B), and a ratio of the weight of said reinforcing fiber aggregates (B) to the total weight of reinforcing fibers in said material is 5-50%.

Abstract: A stampable sheet includes a skin layer and a core layer characterized in that the core layer comprises a thermoplastic resin and a carbon fiber nonwoven sheet having fiber bundles of discontinuous carbon fibers, the carbon fiber nonwoven sheet contains at least five fiber bundles (A) having a bundle width of at least 150 ?m in 100 mm×100 mm of stampable sheet, and the skin layer comprises a thermoplastic resin and a strengthened fiber nonwoven sheet having opened discontinuous strengthened fibers.

Abstract: A carbon fiber composite material which includes a carbon fiber sheet as a reinforcing material and a thermoplastic resin as a matrix resin, the carbon fiber sheet exhibiting a work per areal weight of 1×10?3 to 30×10?3 [(N·mm)/(g/m2)] in a tensile test using a specimen having a width of 25 mm. The carbon fiber composite material exhibits excellent flowability in molding and ensures excellent moldability even when molded into a complicated shape. Further, the composite material can yield a molded product which has high mechanical properties with minimized dispersion, thus being suitable for press molding.

Abstract: A carbon-fiber-reinforced plastic prepared by impregnating a matrix resin into a sheet-like base material includes discontinuous carbon fibers, wherein a content ratio of carbon fibers having lengths of 10 mm or longer in the base material is 60 wt % or more relative to a total amount of the carbon fibers, and an average value of orientation degrees of carbon fibers contained in the base material is 2-10.

Abstract: A carbon fiber nonwoven fabric in which carbon fibers are sized with an aliphatic compound having a plurality of epoxy groups or a specific aromatic compound; the number average x of carbon fibers forming a carbon fiber bundle, in which the number of carbon fibers forming the carbon fiber bundle is 90 or more, is 90 to 1,000 fibers per bundle among the carbon fiber bundles in the carbon fiber nonwoven fabric; and the standard deviation ? of the number of carbon fibers forming the carbon fiber bundle is 50 to 500.

Abstract: A stampable sheet includes a resin and carbon fiber sheet including fiber bundles of discontinuous carbon fibers, wherein the carbon fiber sheet includes fiber bundles having a bundle width of 50 ?m or greater and opened fibers ranging from fiber bundles having a bundle width less than 50 ?m to fibers obtained by opening to the single-fiber level. When the direction along which the opened fibers have been oriented most is a 0° direction and the range of from the 0° to 90° direction is divided into angular zones, the distribution curve showing the proportion of the number of fiber bundles in each angular zone to that in all angular zones and the distribution curve showing the proportion of the number of opened fibers in each angular zone to that in all angular zones are reverse to each other in terms of gradient of the 0° to 90° direction.

Abstract: A stampable sheet includes discontinuous carbon fibers and a thermoplastic resin as a matrix resin, wherein viscosity ? of the stampable sheet in a state where the matrix resin in the stampable sheet is molten is ?0??<?0 exp(0.20Vf)(Pa·s), and ratio Z of refined carbon fiber bundles (A) in which Mn/(Ln×D) is less than 8.5×10?1 (mg/mm2) to the total weight of carbon fibers in the stampable sheet is 10?Z<70 (wt %). The configuration makes it possible to provide a stampable sheet provided with a controlled range of conditions, and to achieve both high flowability during molding and high mechanical properties after molding.

Abstract: A carbon fiber composite material which includes a carbon fiber sheet as a reinforcing material and a thermoplastic resin as a matrix resin, the carbon fiber sheet exhibiting a work per areal weight of 1×10?3 to 30×10?3 [(N·mm)/(g/m2)] in a tensile test using a specimen having a width of 25 mm. The carbon fiber composite material exhibits excellent flowability in molding and ensures excellent moldability even when molded into a complicated shape. Further, the composite material can yield a molded product which has high mechanical properties with minimized dispersion, thus being suitable for press molding.

Abstract: A carbon fiber composite material includes the material is made of carbon fibers and a thermoplastic resin; the proportion Y, relative to the total weight of carbon fibers, of carbon fiber bundles for which Mn/(Ln×D) is 8.5×10?1 (mg/mm2) or more, is 30?Y<90 (wt %); the average value X of Mn/Ln for the carbon fiber bundles is 1.1×10?2?X?8.1×10?2 (mg/mm); and Y satisfies Y?100X+30, wherein Mn: weight of carbon fiber bundles, Ln: fiber length of carbon fibers, D: fiber diameter of carbon fibers. The carbon fiber composite material combines high flowability and mechanical properties, has few variations in mechanical properties and shows an excellent adaptability of carbon fibers for small parts such as ribs.

Abstract: A carbon-fiber-reinforced plastic prepared by impregnating a matrix resin into a sheet-like base material includes discontinuous carbon fibers, wherein a content ratio of carbon fibers having lengths of 10 mm or longer in the base material is 60 wt % or more relative to a total amount of the carbon fibers, and an average value of orientation degrees of carbon fibers contained in the base material is 2-10.