Wet friction member and its manufacturing method

Abstract

A wet friction member contains a pulverized cork heated to 150-200° C. if necessary. The pulverized cork is mixed with other papermaking materials and formed into a paper-made substrate. The paper-made substrate is impregnated with a synthetic resin to be a binder and heated and cured. The cork itself has a high friction coefficient μ. Moreover, a powder thereof increases surface area and area in contact with a separator plate of a counter member, thereby improving a friction coefficient of a friction surface of the wet friction member. The friction coefficient of the cork itself and capacities for absorbing and discharging oil are improved by heating the cork. Thus, there is provided a wet friction member that has a higher friction coefficient μ. An increase in the friction coefficient μ, weight reduction by reducing the number of friction members, and high efficiency are achieved when used as a wet friction member.