Improvements in or relating to the manufacture and production of laminated sheet materials

摘要

552,257. Compound sheet materials. BRITISH CELLOPHANE, Ltd., HEAVEN, G. S., and OSWIN, C. R. Aug. 26, 1941, No. 10893. [Class 140] In adhering water-sensitive fibrous sheets to water-sensitive non-fibrous sheets by an aqueous adhesive the water-absorption of the non-fibrous sheet during the process is kept below that which would bring the water content above the critical range and cause a permanent shrinkage. The fibrous sheets may be paper, cardboard, pasteboard, pulp-board, wood veneer, fabrics of cotton, linen or viscose rayon, parchment, vellum and leather. The non-fibrous sheets may be regenerated cellulose, lowly substituted cellulose ethers, esters and ether-esters, gelatine and alginic materials. The fibrous sheet is coated with the adhesive in an amount of which the water content is insufficient to raise the moisturecontent of the non-fibrous sheet above the critical range when the latter in any condition is brought into contact with the fibrous sheet. Alternatively, the non-fibrous sheet is coated with the adhesive and applied to the dry fibrous sheet so rapidly that the water in the adhesive is absorbed by the fibrous sheet and prevents the water-content of the non-fibrous sheet from exceeding the critical range. When the amount of adhesive applied to the non-fibrous sheet is sufficient to raise its moisture content above the critical range, the time that elapses before contact with the fibrous sheet should be less than the time of imbibition. Non-fibrous sheets may be applied to both sides of the fibrous sheet. The adhesive may be applied to both the fibrous and non-fibrous sheets. The non-fibrous sheets may be sized, dyed, printed or decorated. The process may be carriedout discontinuously with sheets or continuously with webs. Suitable adhesives comprise gelatine and calcium or zinc chlorides, gelatine and acetic acid or pyridine, water-soluble cellulose derivatives, starch, dextrin or gum arabic. Urea, glycerin or glucose may be added. The laminated product may be coated with a moisture proof coating for example as described in Specification 283,109, [Class 140]. It may be used for making bags, envelopes, seamed sheaths and tubes. Specifications 386,775, [Class IV], and 548,531 also are referred to.