Patent ID: 7919175

Claim:
A safety glazing comprising an impact zone; and, adhered firmly to the impact zone, an anti-spall zone; wherein the anti-spall zone comprises a polymer sheet having a first surface that is adhered firmly to the impact zone and a second surface that is adhered firmly to a polymer film, said polymer sheet comprising a poly(vinyl butyral) composition; and wherein the impact zone comprises n glass sheets and at least (n−1) ionomer sheets, wherein n is an integer and 3≦n≦10, wherein each adjacent pair of glass sheets is interspaced by at least one ionomer sheet, and wherein the glass sheets and the at least one ionomer sheet are adhered firmly by lamination; wherein each of the at least (n−1) ionomer sheets comprises an ionomer composition, said ionomer composition comprising an ionomer, said ionomer derived from a parent acid copolymer that comprises copolymerized units of an α-olefin having from 2 to 10 carbon atoms and, based on the total weight of the parent acid copolymer, from about 20 to about 30 wt % of copolymerized units of an α,β-ethylenically unsaturated carboxylic acid having 3 to 8 carbon atoms; wherein about 20 mole % to about 50 mole %, based on the total number of moles of copolymerized units of α,β-ethylenically unsaturated carboxylic acid in the parent acid copolymer, of the carboxylic acid groups of the ionomer are neutralized to form carboxylate groups; wherein the ionomer further comprises cations as counterions to the carboxylate groups; and wherein the ionomer composition in each of the ionomer sheets may be the same or different; and further wherein each ionomer sheet has a thickness; the ionomer sheet that is closest to the anti-spall zone has a thickness of about 2 to about 20 mm; the ionomer sheet that is furthest from the anti-spall zone has a thickness of about 1 to about 10 mm; the ionomer sheet that is closest to the anti-spall zone has the greatest thickness; and the ionomer sheet that is furthest from the anti-spall zone has the smallest thickness.