The invention concerns a process for electrochemically producing a carbonaceous material with its surface modified by organic groups, in particular functionalized organic groups. The process comprises providing a solution, in a protic or aprotic solvent, comprising a salt of a carboxylate of an organic residue capable of undergoing a Kolbe reaction. The solution is then put in contact with a carbonaceous material, wherein the carbonaceous material is positively polarized with respect to a cathode that is also in contact with the solution. The solution may optionally contain an electrolyte. The invention also concerns carbonaceous materials modified at the surface with arylmethyl groups and the use of these modified materials, for example, in the production of composite materials.

Carbon commutator parts used as races for brushes in electric motors are typically soldered to copper carriers. The solder does not bond well unless a metallic coating is first placed on the carbon part. To improve adhesion between the metallic coating and the carbon part, the surface must first be roughened. An improved method of roughening the surface involves immersing the carbon part in an aqueous solution of sodium hydroxide or potassium hydroxide, connecting the carbon part as an anode, and applying an electric current for two or three minutes. This produces oxidation on the surface of the pressed body, thereby roughening its surface, so that the solderable metallic coating will subsequently adhere much better.

Carbon fibers with a surface oxygen concentration (O/C ratio) of 0.20 or less as measured by X-ray photoelectron spectroscopy, a surface concentration of hydroxyl groups (C--OH/C ratio) of 0.5% or greater as measured by chemical modification X-ray photoelectron spectroscopy and a surface concentration of carboxylic groups (COOH/C ratio) of 2.0% or less as measured by chemical modification X-ray photoelectron spectroscopy, and comprising applied as a sizing agent an aliphatic compound which has multiple epoxy groups or an aromatic compound which has multiple epoxy groups, the number of atoms between the epoxy groups and an aromatic ring being 6 or greater. They are prepared by electrolyzing a carbon fiber in an alkaline aqueous solution, or electrolyzing a carbon fiber in an acidic aqueous solution followed by washing with an alkaline aqueous solution, and then applying a sizing agent of an aliphatic compound with multiple epoxy groups or an aromatic compound with multiple epoxy groups in which the number of atoms between the epoxy groups and an aromatic ring is 6 or greater. Alternatively, they are prepared by electrolyzing a carbon fiber in an aqueous solution of an ammonium salt and then applying a sizing agent of an aliphatic compound with multiple epoxy groups or an aromatic compound with multiple epoxy groups in which the number of atoms between the epoxy groups and an aromatic ring is 6 or greater.

Carbon fibers with a surface oxygen concentration (O/C ratio) of 0.20 or less as measured by X-ray photoelectron spectroscopy, a surface concentration of hydroxyl groups (C--OH/C ratio) of 0.5% or greater as measured by chemical modification X-ray photoelectron spectroscopy and a surface concentration of carboxylic groups (COOH/C ratio) of 2.0% or less as measured by chemical modification X-ray photoelectron spectroscopy, and an aliphatic compound applied as a sizing agent which has multiple epoxy groups or an aromatic compound which has multiple epoxy groups, the number of atoms between the epoxy groups and an aromatic ring being 6 or greater.

A process for preparing carbon fibers including electrolyzing a carbon fiber in an alkaline aqueous solution, or electrolyzing a carbon fiber in an acidic aqueous solution followed by washing with an alkaline aqueous solution, and then applying a sizing agent of an aliphatic compound with multiple epoxy groups or an aromatic compound with multiple epoxy groups in which the number of atoms between the epoxy groups and an aromatic ring is 6 or greater. Alternatively, the carbon fibers are prepared by electrolyzing a carbon fiber in an aqueous solution of an ammonium salt and then applying a sizing agent of an aliphatic compound with multiple epoxy groups or an aromatic compound with multiple epoxy groups in which the number of atoms between the epoxy groups and an aromatic ring is 6 or greater.