Asbestos-free felt for prodn. of high temp.-resistant gaskets etc. - contains mineral fibres, fillers and conventional binders, but no fibrillated (pulp) fibres

摘要

Asbestos-free non-woven fabric (I) based on mineral fibres (II), fillers and conventional binders is claimed. (I) contains no pulp fibre (III) and contains only mineral fibre (II) as support. Also claimed is a process for the prodn. of (I) on a wire web machine, by reversing the charge on (II) with a polymer (IV) in the pulp slurry, adding the latex to the slurry only just before putting it on the screen, precipitating with a salt and depositing the fabric on the screen with a unit wt. of more than 300 g/m2. USE/ADVANTAGE - Used for the prodn. of high temp.-resistant seals, esp. cylinder head gaskets, exhaust gaskets and other gaskets which are exposed to high temps. (claimed). The invention provides an asbestos-free gasket material which is prepd. without using fibrillated fibres (pulp fibres - III). These are organic fibres which are commonly used as process aids to maintain the same compsn. at the upper and lower sides of the fabric and reduce the amt. of material falling through the screen; however, even aramid fibres begin to decompose at 250-300 deg. C, which results in vol. shrinkage and failure of the gasket. Omission of pulp fibres also gives a redn. in cost.