Abstract: There is disclosed a method of producing a pre-oxidation fiber in the production of the pre-oxidation fiber by subjecting a polyacrylic precursor fiber to pre-oxidation processing in an oxidizing atmosphere, including shrinking the precursor fiber as a pretreatment of pre-oxidation at a load of 0.58 g/tex or less in the temperature range of 220 to 260° C. under conditions in which the degree of cyclization (I1620/I2240) of the precursor fiber measured by a Fourier transform infrared spectrophotometer (FT-IR) does not exceed 7%, initially-drawing the precursor fiber at a load of 2.7 to 3.5 g/tex in an oxidizing atmosphere at 230 to 260° C. in the ranges of the degree of cyclization of not exceeding 27% and of the density of not exceeding 1.2 g/cm3, and then subjecting the pre-oxidation fiber to pre-oxidation treatment.

Abstract: A carbon fiber strand obtained by bundling 20,000-30,000 carbon fibers each having, in the surface thereof, creases which are parallel to the fiber-axis direction. In an examination with a scanning probe microscope, the creases in the carbon fiber surface are apart from each other at a distance of 120-160 nm and have a depth of 12-23 nm, excluding 23 nm. The carbon fibers have an average fiber diameter of 4.5-6.5 nm, specific surface area of 0.9-2.3 m2/g, and density of 1.76 g/cm3 or higher. The carbon strand has a tensile strength of 5,900 MPa or higher and a tensile modulus of 300 GPa or higher. When would on a bobbin at a tension of 9.8 N, the strand on the bobbin has a width of 5.5 mm or larger. When the carbon fiber strand is examined by a strand splitting evaluation method in which the strand is caused to run through three stainless-steel rods while applying a tension of 9.8 N thereto, no strand splitting is observed.

Abstract: A carbon fiber strand which is produced by obtaining a solidified-yarn strand by spinning with a spinneret having 20,000-30,000 spinning holes, passing the strand through an interlacing nozzle having an air blowing pressure of 20-60 kPa to obtain precursor fibers, oxidizing them in heated air having a temperature of 200-280° C. to obtain oxidized fibers, subjecting these oxidized fibers to a first carbonization treatment in an inert-gas atmosphere at a temperature of 300-900° C. in which the fibers are firstly stretched in a stretch ratio of 1.03-1.06 and then secondarily stretched in a stretch ratio of 0.9-1.01, subsequently conducting a second carbonization treatment in an inert-gas atmosphere at 1,360-2,100° C., and then conducting a surface oxidization treatment in an aqueous solution of an inorganic acid salt in a quantity of electricity of 20-100 C per g of the carbon fibers.

Abstract: The present invention relates to a carbon fiber having enhanced surface properties, tensile strength and tensile modulus to be able to obtain a composite material having high composite properties such as excellent impact resistance, preferably a carbon fiber of which tensile modulus is greater than or equal to 340 GPa and tensile strength is greater than or equal to 5970 MPa. The carbon fiber has the properties that the compression strength in the transverse direction of monofilament of the carbon fiber is greater than or equal to 130 kgf/mm2, the surface oxygen concentration (O/C) of the carbon fiber is in the range of 20 to 30%, and the value of the specific surface area of the carbon fiber based on a BET method by krypton absorption is in the range of 0.65 to 2.5 m2/g. The present invention also relates to a composite material including the carbon fiber and a matrix resin wherein the compression strength after impact is preferably greater than or equal to 220 MPa.

Abstract: There is disclosed a method of producing a pre-oxidation fiber in the production of the pre-oxidation fiber by subjecting a polyacrylic precursor fiber to pre-oxidation processing in an oxidizing atmosphere, including shrinking the precursor fiber as a pretreatment of pre-oxidation at a load of 0.58 g/tex or less in the temperature range of 220 to 260° C. under conditions in which the degree of cyclization (I1620/I2240) of the precursor fiber measured by a Fourier transform infrared spectrophotometer (FT-IR) does not exceed 7%, initially-drawing the precursor fiber at a load of 2.7 to 3.5 g/tex in an oxidizing atmosphere at 230 to 260° C. in the ranges of the degree of cyclization of not exceeding 27% and of the density of not exceeding 1.2 g/cm3, and then subjecting the pre-oxidation fiber to pre-oxidation treatment.

Abstract: A carbon fiber strand which is produced by obtaining a solidified-yarn strand by spinning with a spinneret having 20,000-30,000 spinning holes, passing the strand through an interlacing nozzle having an air blowing pressure of 20-60 kPa to obtain precursor fibers, oxidizing them in heated air having a temperature of 200-280° C. to obtain oxidized fibers, subjecting these oxidized fibers to a first carbonization treatment in an inert-gas atmosphere at a temperature of 300-900° C. in which the fibers are firstly stretched in a stretch ratio of 1.03-1.06 and then secondarily stretched in a stretch ratio of 0.9-1.01, subsequently conducting a second carbonization treatment in an inert-gas atmosphere at 1,360-2,100° C., and then conducting a surface oxidization treatment in an aqueous solution of an inorganic acid salt in a quantity of electricity of 20-100 C per g of the carbon fibers.

Abstract: A carbon fiber strand obtained by bundling 20,000-30,000 carbon fibers each having, in the surface thereof, creases which are parallel to the fiber-axis direction. In an examination with a scanning probe microscope, the creases in the carbon fiber surface are apart from each other at a distance of 120-160 nm and have a depth of 12-23 nm, excluding 23 nm. The carbon fibers have an average fiber diameter of 4.5-6.5 nm, specific surface area of 0.9-2.3 m2/g, and density of 1.76 g/cm3 or higher. The carbon strand has a tensile strength of 5,900 MPa or higher and a tensile modulus of 300 GPa or higher. When would on a bobbin at a tension of 9.8 N, the strand on the bobbin has a width of 5.5 mm or larger. When the carbon fiber strand is examined by a strand splitting evaluation method in which the strand is caused to run through three stainless-steel rods while applying a tension of 9.8 N thereto, no strand splitting is observed.

Abstract: According to the present invention, there is disclosed a carbon fiber having a strand tensile strength of 6,100 MPa or more, a strand tensile modulus of 340 GPa or more and a density of 1.76 g/cm3 or more and possessing, on the surface, striations oriented in a direction parallel to the fiber axis, wherein the distance between striations in a 2×2 ?m area of the carbon fiber surface when observed by a scanning probe microscope is 0.1 to 0.3 ?m, the root mean square surface roughness Rms (5 ?m) in a 5×5 ?m area of the carbon fiber surface when observed by a scanning probe microscope is 20 to 40 nm, and the root mean square surface roughness Rms (0.5 ?m) when measured in a 0.5×0.5 ?m area is 2 to 12 nm.

Abstract: According to the present invention, there is disclosed a carbon fiber having a strand tensile strength of 6,100 MPa or more, a strand tensile modulus of 340 GPa or more and a density of 1.76 g/cm3 or more and possessing, on the surface, striations oriented in a direction parallel to the fiber axis, wherein the distance between striations in a 2×2 ?m area of the carbon fiber surface when observed by a scanning probe microscope is 0.1 to 0.3 ?m, the root mean square surface roughness Rms (5 ?m) in a 5×5 ?m area of the carbon fiber surface when observed by a scanning probe microscope is 20 to 40 nm, and the root mean square surface roughness Rms (0.5 ?m) when measured in a 0.5×0.5 ?m area is 2 to 12 nm.

Abstract: A process for preparing a retort-proof laminate for packaging foodstuffs which comprises laminating an aluminum substrate to at least one polyolefin film selected from the group consisting of high density-polyethylene, polypropylene, ethylene-propylene copolymers and polybutene films using as an adhesive a specific polyolefin resin in melted state prepared by combining together (A) at least one member selected from the group consisting of high-density polyethylene, polypropylene ethylene-propylene copolymers and polybutene, (B) maleic anhydride and (C) aluminum hydroxide, and by rendering said specific polyolefin resin substantially free from unreacted maleic anhydride and low molecular weight maleic anhydide homopolymers.The process also includes preparing a retort-proof coated aluminum substrate for packaging foodstuffs which comprises coating an aluminum substrate with a layer formed from the above-described specific polyolefin resin and thereafter forming a suitable retort packaging container therefrom.