Abstract: A sizing agent for matrix-resin-reinforcement fibers that simultaneously attains excellent cohesion and abrasion resistance of sized fibers, uniform size application on fiber surface and good bonding between sized fiber and a matrix resin; a synthetic fiber strand sized therewith; and a fiber-reinforced composite material reinforced by the sized fiber strand. The sizing agent contains a polyamide (A), a carbodiimide group-containing compound (B) and water (C), wherein the polyamide (A) has a melt viscosity ranging from 100 to 15,000 mPa·s at 150° C. and the compound (B) has at least two carbodiimide groups per molecule. The polyamide (A) is preferably a water-soluble polyamide.

Abstract: A sizing agent for matrix-resin-reinforcement fiber, a synthetic fiber strand sized therewith, and a fiber-reinforced composite material reinforced by the sized fiber strand. The sizing agent for reinforcement fiber contains a polyamide (A), a carbodiimide group-containing compound (B) and water (C), wherein the polyamide (A) has a melt viscosity ranging from 100 to 15,000 mP·s at 150° C. and the compound (B) has at least two carbodiimide groups per molecule. The polyamide (A) is preferably a water-soluble polyamide.

Abstract: An acrylic-fiber finish for carbon fiber production is prepared into a stable emulsion and applied to a carbon-fiber precursor to prevent gumming up of finish components in precursor production and carbon fiber fusing in baking process. The acrylic-fiber finish is used for carbon-fiber production and includes a modified silicone having a modifying group containing a nitrogen atom and an acidic phosphate ester represented by the following chemical formula (1). where R1 represents a C6-22 alkyl or alkenyl group, A represents a C2-4 alkylene group, and AO represents an oxyalkylene group, n represents a mole number of oxyalkylene group and is an integer ranging from 0 to 20, and each of a and b is an integer of 1 or 2 and meets the equation a+b=3.

Abstract: An acrylic-fiber finish for carbon fiber production is prepared into a stable emulsion and applied to a carbon-fiber precursor to prevent gumming up of finish components in precursor production and carbon fiber fusing in baking process. The acrylic-fiber finish is used for carbon-fiber production and includes a modified silicone having a modifying group containing a nitrogen atom and an acidic phosphate ester represented by the following chemical formula (1). where R1 represents a C6-22 alkyl or alkenyl group, A represents a C2-4 alkylene group, and AO represents an oxyalkylene group, n represents a mole number of oxyalkylene group and is an integer ranging from 0 to 20, and each of a and b is an integer of 1 or 2 and meets the equation a+b=3.

Abstract: An acrylic-fiber finish for use in carbon-fiber production contributes to high tenacity of resultant carbon fiber. The acrylic-fiber finish for carbon-fiber production includes an epoxy-polyether-modified silicone and a surfactant. The weight ratios of the epoxy-polyether-modified silicone and the surfactant in the total of the non-volatile components of the finish respectively range from 1 to 95 wt % and from 5 to 50 wt %. The carbon fiber production method includes a fiber production process for producing an acrylic fiber for carbon-fiber production by applying the finish to an acrylic fiber which is a basic material for the acrylic fiber for carbon-fiber production; an oxidative stabilization process for converting the acrylic fiber produced in the fiber production process into oxidized fiber in an oxidative atmosphere at 200 to 300 deg.C.; and a carbonization process for carbonizing the oxidized fiber in an inert atmosphere at 300 to 2,000 deg.C.

Abstract: An acrylic-fiber finish for use in carbon-fiber production contributes to high tenacity of resultant carbon fiber. The acrylic-fiber finish for carbon-fiber production includes an epoxy-polyether-modified silicone and a surfactant. The weight ratios of the epoxy-polyether-modified silicone and the surfactant in the total of the non-volatile components of the finish respectively range from 1 to 95 wt % and from 5 to 50 wt %. The carbon fiber production method includes a fiber production process for producing an acrylic fiber for carbon-fiber production by applying the finish to an acrylic fiber which is a basic material for the acrylic fiber for carbon-fiber production; an oxidative stabilization process for converting the acrylic fiber produced in the fiber production process into oxidized fiber in an oxidative atmosphere at 200 to 300 deg.C.; and a carbonization process for carbonizing the oxidized fiber in an inert atmosphere at 300 to 2,000 deg.C.