FRANK A SOSKA
Engineers in New Kensington, PA

4040888, Aug 9, 1977

Oct 1, 1975

5/618587

Frank A. Soska - Arnold PA
Lyle L. Shumaker - Natrona Heights PA

PPG Industries, Inc. - Pittsburgh PA

B32B 3100, B30B 304

156497

Laminated safety glass panels comprising sheets of rigid transparent material, such as glass, polycarbonate, acrylic plastic, polyester and the like, alternating with interlayer materials, such as polyvinyl butyral, polyurethane and the like, are prepressed to remove entrapped air at the interfacial surfaces to prepare the assemblies for final lamination. When the relatively rigid plies to be laminated have unsmooth surfaces, such as wavy surfaces, or surfaces having imperfections due to the penetration of the sheet during thermal treatment by tongs or other solid members that engage the rigid transparent sheet during its heat treatment prior to assembly for lamination, the preliminary pressing performed by the prior art techniques is insufficient to prevent oil from an oil autoclave used in the final laminating step from penetrating into the interfacial surfaces between adjacent rigid and relatively flexible layers of the assembly to be laminated. The present invention provides a novel package comprising apparatus enclosing the assembly to be laminated during the prepressing operation. The apparatus comprises a novel peripheral evacuation chamber so related to the assembly to be laminated as to enable existing autoclaves to complete the laminating operation while preventing the oil in the autoclave from penetrating into the vision area of the laminate along the interfacial surfaces between rigid and flexible layers of the laminated transparent window that results, which oil penetration causes a reject of the fabricated window.