GB442002A - Improvements in or relating to saturated fibrous sheet material and process of producing the same - Google Patents

Abstract

442,002. Treating pulp web. STEVENS, A. H., 5, Quality Court, Chancery Lane, London.-(Raybestos Co. ; 1427, Railroad Avenue, Bridgeport, Connecticut, U.S.A.) April 28, 1934, No. 12896. [Classes 96 and 140] An impregnated paper, fibre sheet or board in which the fibres are both coated by and united together by means of a continuous binding medium such as indiarubber, is made from newly-formed wet web as produced in a paper-making machine, by confining the web between porous surfaces, passing the so-confined web through a bath of saturant liquid embodying the binding medium, freeing the saturated web from the confinement of the porous surfaces in such a manner that the web while suitably supported is permitted to swell up and absorb the excess saturant liquid, and finally condensing the web and removing excess saturant by passage through condensing rolls. As shown, the web 5 is taken off the blanket 6 of a paper-making machine and is transferred to a porous screen belt 9 ; by means of a rotatable screen roll 16 moving at the same speed as the belt 9, the web carried between the roll and belt, is carried through a bath of saturant liquid 14 ; the roll and belt separate as they leave the bath, the web remaining on the belt 9 by means of which it traverses the distance between the bath and the couch rolls 11, 18, and during the time so taken is permitted to swell up and absorb excess saturant liquid ; the condensed web may be permitted to wind up on the couch roll 18 to produce a multi-ply sheet. Instead of the screen roll, an upper porous screen belt may be employed; and further the bath may be constituted by a spray on the upper screen in conjunction with an overflowing reservoir making contact with the lower screen belt. As shown, the felted wet web is formed on a suction cylinder 1 that rotates partly immersed in the pulp suspension 3, the web being transferred to the blanket 6, such transference being assisted by a couch roll 7. The saturant liquid constituting the binding medium may be a solution or suspension of rubber latex, phenolic resin, starch, shellac, glue, viscose, sodium silicate, oil or asphalt, soap or rosin size ; and with the liquid there may be incorporated salts, dyes, fillers, pigments, clay or reagents to act on the paper. When rubber latex is employed, there may be added to the saturant liquid or to the paper stock, vulcanizing agents, accelerators, antioxidants, preservatives and fillers.