Paper sheets and tapes

摘要

869,231. Paper compressed parallel to its surface; adhesive tape. DUNLAP, I. R. Nov. 22, 1957 [Nov. 23, 1956], No. 36533/57. Classes 96 and 140. A web of paper P, e.g. for adhesive tapes, is compressed longitudinally or transversely, as by passing it between a heated drum 13 and a belt 15, e.g. of natural rubber reinforced by canvas or cords &c., the surface of the belt which contacts the paper being of sufficient hardness and extensibility to extend over a guide roll 10, and contract over the drum 13 &c., the pressure of the belt against the drum 13 &c. preventing the paper from crÛping as it contracts with the belt. The fibres of the paper are bonded, e.g. by beater impregnation using an elastomeric polymer latex, or by saturating the paper web before or after compressing it with natural or synthetic rubber, resin-modified rubbery polymers, or glue-glycerine, or by impregnating it with non-aqueous solutions of pitches, resins, or gums, or rubber, e.g. modified by resins, plasticizers, &c. The weight of impregnant may be 30 to 150% of the raw paper. The treated paper may be coated with usual tacky, solvent-actuated or pressuresensitive adherence, e.g. based on natural rubber, polyisoprene, butadiene-styrene, &c., e.g. using conventional tackifiers and optionally fillers, e.g. zinc oxide, magnesium carbonate, calcium carbonate, lead oxide, clay, titanium dioxide, aluminium, hydrated alumina, pulverized glass, or silica, antioxidants, &c. An Example (1) mentions rope paper compressed to 65% of its original length impregnated with a specified synthetic rubber mix. Another Example (3) mentions crÛped kraft paper similarly treated. In a modification a moisture-permeable belt extends round a heated drying drum. Specification 611,211 is referred to.