Patent ID: 7919165

Claim:
A wet-type friction material usable for a clutch required to be closely contacted with an outer peripheral part of a frictional surface of a counterpart member having a fixed inclination, comprising: a core metal of a flat ring shape; and a friction material substrate adhered and fixed to at least one surface of the core metal, the friction material substrate consisting of a ring-shaped friction material substrate or a plurality of segmented friction material substrates, each of the ring-shaped friction material substrate and the segmented friction substrate being cut out of a friction material substrate; wherein the friction material substrate has a thickness decreasing part and a constant thickness part, and the thickness decreasing part decreases a thickness linearly in a radial direction of the friction material substrate from a middle point to the outer peripheral edge of the friction material substrate so that the friction material substrate decreases the thickness in accordance with the inclination of the frictional surface of the counterpart member at the thickness decreasing part, and wherein the constant thickness part is provided at a part other than the thickness decreasing part, the constant thickness part has a constant thickness in the radial direction of the friction material substrate, and the constant thickness part is formed at an inner peripheral side in the radial direction of the friction material substrate, while the thickness decreasing part is formed at an outer peripheral side in the radial direction of the friction material substrate.