Patent GB-613529-A (GB)
Title: Improvements in light-weight compound sheet materials
IPC: B32B37/14
Filed: 1945-12-15
Abstract: 613,529. Compound sheet materials. LIBBEY-OWENS-FORD GLASS CO. Dec. 15, 1945, No. 34008. Convention date, Dec. 16, 1944. [Class 140] [Also in Group V] A light-weight compound sheet material comprises a cellular layer which is rigid in compression and in which the cell walls are composed of glass cloth impregnated with a hardened adhesive, and a skin of glass cloth, which may be similarly impregnated, cemented to each side of the cellular layer. The glass cloth may contain some cotton threads. The adhesive for impregnating the layers and cementing them together may be a phenol-, urea-, or melaminemerizable unsaturated polyester, a formaldehyde resin, or a polydiallyl ester, such as the phthalate or oxalate, or a mixture. The polymerizable unsaturated polyester may be prepared from an unsaturated polybasic acid such as maleic, fumaric, itaconic, citraconic, or mesaconic acid and a dihydric alcolhol such as polymethylene glycols from ethylene to decamethylene glycol, propylene or any butylene glycol, polyethylene glycols from diethylene to nonaethylene glycol, dipropylene glycol, glycerol monoesters or monoethers, dihydroxyalkanes from dihydroxy butane to dihydroxydecane. Other acids and alcohols, e.g. citric acid, resin acids, or glycerol, may be incorporated. The polymerisable polyester may be used in solution together with one or more polymerisable monomeric substances such as styrene, vinyl acetate, methyl acrylate or methacrylate. The cellular layer may consist of corrugated strips of glass fabric assembled to form cells, and may be a slice 2, Fig. 1, cut from a block 1 made by cementing together sheets of corrugated glass fabric impregnated with adhesive. The sheets may be corrugated before assembly, or freshly-impregnated fabric may be assembled with removable round or hexagonal rods or inflatable rubber tubes and pressed while the adhesive hardens. The rods may be of fusible alloy or plastic and melted out of the stack. Alternatively, the cellular layer may be sliced from a block consisting of adhesively-united glass fabric tubes with or without interposed flat sheets to assist stacking. Both the cellular layer and the outer skins of glass cloth may be dipped in the hardenable adhesive before uniting. Other cellular layers may be made of superposed corrugated layers 8, Fig. 5, united with the corrugations crossing and, if desired, with interposed flat layers 9, or notched strips 10, Fig. 6, assembled to form rectangular cells. The Specification as open to inspection under Sect. 91 describes also cellular cores formed from moulding powder, from fabrics such as canvas, cotton, rayon, silk, linen, or wool, from paper, or from a single layer of knitted fabric deeply embossed. The material for forming the corrugated layers may consist of a layer of glass fibre threads parallel to the corrugations to each side of which is cemented a layer of glass fabric. The block 1, Fig. 1, may be made by uniting layers of glass fabric coated with spaced bands of adhesive, the joins between successive layers being staggered so that the flat material may be expanded so as to form a block with hexagonal cells. The expanded material is impregnated with adhesive and hardened. This subjectmatter does not appear in the Specification as accepted.