An Acrylic Rubber Modified Phenolic Resin Which Has Good Flexibility at Low Temperature
Phenolic resins have been widely used as a binder for friction materials such as disk pads and brake linings. Brake noise has been one of the key requirements and outstanding issues in brake manufacturer, especially the study of and elimination of brake noise at low temperatures. In an effort to reduce brake noise, we have traditionally developed elastomer modified phenolic resins, which give good flexibility to disk pads. A typical elastomer is an acrylic rubber (AR) that is very effective in reducing brake noise. A general AR gives good flexibility to the phenolic resin at room temperature but the flexibility decreases at low temperatures. The reason is that the physical properties such as hardness and viscoelasticity change at the glass transition temperature (Tg) of an elastomer and Tg of the general AR modified resin is around 0°C. Therefore, it is difficult to reduce the brake noise at low temperature using a general AR.