Patent ID: 8876680

Claim:
A plate-shaped disc member base material comprising an inorganic fiber, mica, and a kibushi clay having a content of particle components that have a particle size of 5 gm or larger of not higher than 30% by weight based on the weight of the kibushi clay, the kibushi clay being either elutriated or subjected to a wet sizing separation purification process, and the kibushi clay being configured to be sintered by heat applied thereto upon use of a disc roll formed therefrom to give a hardening action, the disc roll being formed from a plurality of annular disc members formed with the plate-shaped disc member base material, wherein said kibushi clay has a content of impurities of 10% by weight or less based on the weight of the clay, wherein said inorganic fiber is present in an amount of 20 to 40% by weight based on the total weight of said disc member base material, and said kibushi clay is present in an amount of 20 to 40% by weight based on the total weight of said disc member base material, and wherein said mica is present in an amount of 20 to 35% by weight based on the total weight of the disc member base material.