GB395197A - Improvements in processes for waterproofing paper by means of viscose - Google Patents

Abstract

395,197. Waterproofing paper and fabrics; compound sheet materials. SOC. ANON. PAPETERIES NAVARRE, 52, Avenue du Marechal Foch, Lyons, France. Sept. 22, 1932, No. 26410. Convention date, Sept. 22, 1931. [Classes 96 and 140.] Paper is waterproofed by passing it in the form of a band upwardly through a bath of viscose and' then successively through baths for coagulating and precipitating the viscose, the band being finally washed and dried. As shown, the band B passes upwardly through a viscose bath A and then through baths J, N in which coagulation and precipitation are effected. Between the baths A, J adjustable expression rollers G, G<1> are provided, the bath A being movable relatively to the rollers. Between the baths J, N, and after the bath N, expression rollers L<1>, L<11>, P<1>, P<11>and guide rollers L, P are provided, the rollers L, P and, if desired, the bath J, being vertically movable. A second precipitating bath R may also be provided. The rollers K, 0 mounted in the baths J, N are movable relatively to the baths. The band may be passed more than once through the viscose bath before coagulation, preferably without intermediate drying, more than one viscose bath being provided if desired. Also, before coagulation, a number of bands, one or some of which may be made of fabric, may be impregnated with viscose and superimposed, or compound sheets comprising impregnated and unimpregnated bands may be prepared. The coagulation bath J may consist of a neutral salt solution, an alcohol, or a weak acid such as carbonic, acetic or formic acid. The precipitation bath N may consist of a mineral acid, with or without a salt. Means for filtering and regenerating the precipitation bath may be provided, or alternatively the spent precipitation bath may be used as the coagulation bath ; in the latter case the baths J, N may be substituted by a single long bath having a coagulating composition at one end and a precipitating composition at the other. In washing the band after the precipitation, the final washing may be effected with water containing a little ammonia ; the band may then be dried under tension or under conditions preventing contraction. The product may be subjected to the usual finishing treatments. such as calendering, smoothing, frictioning, craping, gumming, printing, or dyeing. The Specification as open to inspection under Sect. 91 states that fabrics may be treated as described above, and that the coagulation of the viscose may be effected by heat or electricity. This subject-matter does not appear in the Specification as accepted.