Low-density friction materials, esp. for dry clutch linings - by press-moulding and heating a blank contg. gas-producing, density-reducing additives, e.g., bicarbonate, organic blowing agent, water, etc.

摘要

Prepn. of low-density friction materials (I), esp. friction linings for dry clutches, in which a moulded blank (II) contg. the components of (I) is subjected to a press process and opt. a first and/or final thermal post-treatment. Before press-moulding, (II) is treated with one or more reagents (III) which have the effect of reducing the density of the final prod.; (III) are given off as gas, or decomposed with cleavage of gaseous mols. and/or complete conversion into volatile prods. during the above process, which is carried out in such a way as to prevent shrinkage of (II) as far as possible. Also claimed is a friction material produced by this process, esp. friction linings for dry clutches, pref. in the form of bulk-pressed linings with density 1-1.5 g/cm3 and rolled linings with density 1.2-1.5 g/cm3. USE/ADVANTAGE - The process enables the prodn. of new clutch lining materials (esp. for cars, etc.) with the required durability, etc., but with density as low as 50% of the theoretical density of the material (cf. 90% under conventional process conditions); this is achieved without significant adverse effect on quality.