Bilayer windshield and preformed two-ply sheet for use therein

Claim 1

A preformed flexible multi-ply transparent sheet, effective for use in a bilayer glazing laminate, having optical, moisture-resistant, and energy-absorbent properties effective for use in a bilayer glazing laminate, one ply which comprises a self-healing thermosetting polymeric material, the other ply which comprises an energy-absorbing polyurethane ply which is substantially non-tacky at room temperature but which is capable of being adhesive under the influence of heat and pressure, wherein said sheet is capable of maintaining, in the absence of an adhesion promoter, effective adhesion as measured by the temperature and moisture conditions of ANSI-Z26 test nos. 3 and 4, said energy-absorbing polyurethane being prepared by reactive casting a solvent-free mixture of monomers; and wherein said multi-ply transparent sheet is produced by: (1) depositing on a horizontal support a liquid film comprising a solvent-free mixture of monomers capable of forming a thermosetting polymeric material; (2) forming a solid film of said thermosetting polymeric material by polymerizing the monomers while on said support; (3) depositing on said supported film a liquid film comprising: (a) an aliphatic or a cycloaliphatic diisocyanate, (b) a polyol component including: (i) about 30 to about 45 OH equivalent percent of a polymeric diol having a molecular weight of about 500 to about 3,000; (ii) about 20 to about 70 OH equivalent percent of a chain extender diol having a molecular weight of less than about 300, the molar ratio of said polymeric diol (i) to said chain extender diol (ii) being about 0.3:1 to about 1:1, and (iii) about 0.05 to about 35 OH equivalent percent of a polyol having an OH functionality greater than 2, the molar ratio of said polymeric diol (i) to said polyol (iii) being about 1.5:1 to 4:1; and (c) a polyurethane catalyst, wherein the NCO/OH ratio of said mixture is about 0.8:1 to about 1:1; (4) forming a solid, optical, energy-absorbing overlaid polyurethane ply within about an hour, thereby forming said multi-ply sheets; and (5) removing said multi-ply sheet from said support.