GB163552A - Improvements in and relating to coated composite sheet material - Google Patents

Abstract

163,552. Alexander, A. E., (Stokes, J. P.). March 24, 1920. Drawings to Specification. Printing-surfaces.-In making composite sheet material which can be moulded and used for printing surfaces &c. consisting of a fibrous body impregnated with a liquid cementitious material capable of setting or hardening in two stages under the action of heat, such as those obtained from phenols by condensation processes, and coatings of cement, the body is heated to such an extent before moulding that instead of remaining soft it becomes dry and crisp. For this purpose the body, which may be made of blotting paper, long fibred chip-board, &c. is soaked in a solution of the cement, passed between rollers to press out excess liquid, and freed from the solvent by heating. Several layers of this sort may be joined together by glue, or a single layer may be used. The sheet thus formed is coated on both sides with a layer of cement containing a high proportion of a filler such as lamp black and heated until the cement is nearly hard. Coatings of cement containing a lower proportion of filler are then applied and the sheet heated until the latter coatings are of such consistency as to be moulded readily by pressure. The sheet is then moulded as desired in a heated press, until the cement is completely set. The lamp black may be replaced by other fillers, such as wood flour, aluminium oxide, barium sulphate, and silex.