GB1382186A - Laminates - Google Patents

Abstract

1382186 Glass-polyurethane laminates PPG INDUSTRIES Inc 1 Dec 1972 55580/72 Heading B5N [Also in Divisions C3 and G1] Energy absorption laminates, e.g. safety glass, comprise a glass sheet bonded to or coated with a layer of a polyurethane derived from (a) a hydroxy-terminated substantially linear, aliphatic polycarbonate, having linkages, of molecular weight 500-5000, (b) a diisocyanate, dithioisocyanate or isocyanatethioisocyanate and (c) a compound of molecular weight less than 250 having at least 2 active H atoms per molecule reactive with isocyanate or thioisocyanate groups. The polyurethane is preferably a random thermoplastic copolymer. In examples, (a) is a poly-(oxyethylene carbonate) glycol prepared from ethylene carbonate and ethylene glycol, (b) is 4,4<SP>1</SP>-methylene-bis- (cyclohexyl isocyanate) of stereoisomeric ratio 55% trans : 45% cio, methylene-bis-(4-phenyl isocyanate) or toluene diisocyanate and (c) is 1,4-butanediol. Laminates may be made by the following techniques (1) air is evacuated from an assembly of glass and polyurethane plies, which is first heated to soften the polyurethane and seal the edges and then heated under pressure, e.g. in an autoclave, to seal the plies. Edge sealing may be dispensed with by using a vacuum bag. The polyurethane plies are formed from the polymerized material by extruding, pouring into trays, milling and/or calendering and are dried before incorporation into the laminate, (2) Two glass plies are spaced apart, e.g. by tape, and liguid polyurethane is poured into the space and cured. (3) Liquid polyurethane is sprayed on to a glass sheet and heat is applied. (4) A glass pressure plate is used to adhere polyurethane to a single glass sheet. When methods (1) and (2) are used to produce glass-polyurethane-glass laminates, one of the glass sheets may be treated with a release agent so that it can subsequently be removed. Adhesion promoters, e.g. alkoxy silanes, and adhesion inhibitors, e.g. alkyl acid phosphates, may be included in the polyure- 'thane reactants or may be applied to the sheets to be assembled. The glass may be chemically strengthened or tinted and may be of thickness 0À065-0À180 inch. The thickness of a polyurethane interlayer may be 5-120, preferably 15-45, mils. The Specification also describes the preparation of a laminate for testing purposes by bonding the polyurethane between two polyethylene films.