Friction material and its manufacturing method

Abstract

A friction material has a resin amount distribution that is the largest at a portion near a non-friction surface, that becomes lower toward an inside and that is the lowest at a portion near a friction surface. For example, such friction material is manufacture as follows. First, two friction materials are overlapped while the friction surfaces faced with each other. Then, the friction materials are dried at a room temperature. At this time, the resin has such a characteristic as to move while dragged by a solvent that dries from the non-friction surface located outside. Using such characteristic, the resin amount at the portion near the friction surface is lessened. Then, a temperature at the friction surface is made low and a temperature at the non-friction surface is made high in a drying step of the friction material. Thereby, the resin amount at the portion near the friction surface is lessened.

1 . A manufacturing method of a friction material comprising the steps of:
 impregnating a resin in a friction material; and   drying the friction material;   wherein the impregnating step includes a step for impregnating resins having different viscosities in a front surface and a rear surface of the friction material, and the drying step includes a step for drying the friction material at a predetermined temperature condition while locating downward a side of the friction material at which the resin having a larger viscosity is contained.   
   
   
       2 . A manufacturing method of a friction material according to  claim 1 , in which the drying step further includes a step for rotating the friction material in drying at the predetermined temperature condition so as to make a distribution of an amount of the resin higher at an outer peripheral portion of the friction material by a centrifugal force in rotating.