Patent GB-1174582-A (GB)
Title: Surface Coverings
Inventor: SINDEN GEORGE
IPC: C08J9/04
Filed: 1966-02-10
Abstract: 1,174,582. Foamed coatings. MARLEY TILE CO. Ltd. 6 Feb., 1967 [10 Feb., 1966], No. 5926/66. Heading B2E. [Also in Division B5] A vinyl chloride homo- or co-polymer foam having a textured surface effect is produced by (1) replacing part of the surface of a prefoamed vinyl chloride homopolymer or copolymer layer by a vinyl chloride homopolymer or copolymer plastisol, the layer and also if desired the plastisol containing a blowing agent and the compositions of the layer and plastisol being selected to have different rates of foaming at the blowing temperatures, and (2) heating e.g. to 165 to 200‹C, to effect foaming whereby areas of the layer with the plastisol on their surface are raised to a different extent to other areas thereby forming foam with a textured surface. The pre-formed vinyl chloride homopolymer or copolymer layer may be formed by applying a coating of a vinyl chloride homopolymer or copolymer plastisol on to a substrate e.g. woven or non-woven fabrics such as paper felt, asbestos paper, woven hessian, woven hessian with needled jute fibres, or if the substrate is to be removed after foaming, a silicone impregnated paper or conveyor, and heating itto effect at least partial gelatin. The plastisol used for replacing part of the surface of the pre-formed layer and the plastisol used for the formation of the pre-formed layer may contain the same blowing agent. The plastisols may contain different proportions of the same blowing agent. An organic compound which liberates nitrogen upon heating may be used as the flowing agent e.g. azodicarbonamide. The plastisol used for replacing part of the surface of the preformed layer and that used for the formation of the pre-formed layer may contain substantially equal proportions of the same blowing agent, one plastisol containing either an accelerator e.g. zinc salt, which serves to increase the extent of foaming of the plastisol, or an inhibitor e.g. oxalic or citric acid, which serves to decrease the extent of foaming of the plastisol. The preformed layer may be formed by calendering and may have a thickness of 0.01 to 0.025. Step (1) may be effected by embossing the surface of the vinyl chloride homo or copolymer layer and in-filling e.g. by knife-spreading, the depressions formed with the vinyl chloride homo or copolymer plastisol. The pre-formed vinyl chloride homo or copolymer layer may have a thickness of about 0.025 inches and the depressions formed by embossing have a depth of from 0.005 to 0.020 inches. After in-filling and before heating to effect blowing, heating is effected at a temperature below the decomposition temperature of the blowing agent or agents e.g. from 140 to 165‹C, to effect at least partial gelation of the plastisol. After in-filling and before heating, a transparent wear layer e.g. of vinyl chloride homo- or co-polymer, may be applied e.g. by coating or laminating; the wear layer may have a thickness of from 0.005 to 0.015 inches. Foaming may be controlled to provide 2- to 4-fold expansion. The pre-formed layer after foaming may have a thickness of from 0.40 to 0.1 inches.