Patent ID: 7150911

Claim:
An electrical insulating vapor grown carbon fiber having a fiber diameter of 0.01 to 0.5 μm, a hollow part in the center of the fiber and a boron concentration formed from a mixture of a boron compound and a vapor grown carbon fiber, the mixture having a boron concentration of about 1 to about 30% by mass in terms of a boron element, wherein the surface thereof is partially or entirely coated with an electrical insulating material of boron nitride and the amount of boron in a depth of 1 nm from the surface of the vapor grown carbon fiber is about 10% by mass or more, based on the entire mass of the vapor grown fiber having a depth of 1 nm from the surface, and wherein the electrical insulating vapor grown carbon fiber has a specific resistivity of 10 3 Ω·cm or more when compressed at a bulk density of 0.8 g/cm 3 .