METHOD OF MAKING A PANEL COMPRISING A PLURALITY OF SHEETS ONE OF WHICH IS A SHEET OF GLASS OR VITROCRYSTALLINE MATERIAL AND PANELS FORMED BY SUCH METHOD

摘要

1359168 Glass laminates GLAVERBEL 21 May 1971 16286/71 Heading B5N [Also in Division C1] A panel incorporates a plurality of sheets 5, 6; 11, 12, 13 or 26, 27, 28, at least one of which is of glass or glass-ceramic, secured together, as by a frame and/or a sheet of organic material, and the one sheet of glass or glassceramic is held in the panel in a state of elastic flexure with the side 2 in which compressive stresses exist as a result of the flexure being located internally of the panel. In each embodiment the sides of the one sheet are numbered 1, 2 and of a second main sheet 3, 4. As shown in Figs. 1 and 2, a glass sheet 5 and acrylic sheet 6, initially flat are flexed when mounted in a frame 7 so that side 2 faces inwardly. Alternatively, the sheets may be curved in opposite directions (outwardly) (as sheets 26, 28) and held in a frame so as to be flat. In either case, the sheets may be glued to an intervening sheet polyvinylbutyral. As shown in Figs. 5 and 6, two glass sheets 11, 13 are curved, in the same direction with one 13 (outwardly) at a greater curvature, and are secured by gluing to an intervening polyvinylbutyral sheet 12 so that the final curvature lies between the two. As shown in Figs. 14, 15, sheets 26 and 28 of glass-ceramic curved in opposite directions are secured either side of a sheet 27 of polyvinylchloride and secured in a frame 29 in a flat condition. A number of other constructions are shown, including the securing of further layers of organic material on the outer faces of the main panel. When two sheets of glass or glass-ceramic are used, the second sheet may be thicker than the first sheet. Two glass or glass-ceramic sheets may be secured together also by sheets of a high molecular weight polycarbonate of a bis-phenol using a polyacrylate or polyvinyl chloride adhesive. Preferably the sheets before assembly are given either a thermal or a chemical tempering to produce inherent compressive stresses in the faces of the sheets. Ion exchange is the preferred method and, for sodium including glass, may either be by substitution of K, Rb or Cs ions or by Li ions. In examples, sheets of soda-lime glass were immersed in a bath of KNO 3 + KCl + NaNO 3 ; KNO 3 or LiNO 3 + NaCl, and sheets of glass-ceramic in a bath of KNO 3 . Specification 1,359,170 is referred to.