GB976194A - Improvements in or relating to the finishing of uncoated paper - Google Patents

Abstract

976,194. Paper-making. BELOIT IRON WORKS. Feb. 7, 1961 [April 4, 1960], No. 4577/61. Heading D2A. An uncoated paper web, which is plasticizable by heat and pressure, is gloss-finished by drying it to a moisture content of less than 35% and immediately thereafter passing it through a nip between two rolls. The first roll is heated to a temperature sufficient to plasticize the fibres of the web in contact with it, and has a smooth surface harder than the cover of the second roll. The second roll comprises a core and an outer deformable and resilient cover having a hardness of less than 30 P and J (<SP>1</SP>/ 8 inch ball). The two rolls are forced together with sufficient pressure to coalesce the plasticized fibres. As shown, paper from a Fourdrinier machine is passed through wet-presses (not shown), and then through a first drier section 63A to bring the moisture content to less than 35%. It is then surface-glossed on each side by being pressed between, on the one hand metal rolls 33 and 51 with smooth surfaces plated with chromium or nickel and internally heated, and on the other hand rolls 34, 35, 52 and 53 with metal cores and resilient cores of the required hardness. The rolls are forced together by the bellows 36. Drying is continued in a further drier section 63B, and the paper is again pressed by further sets of rolls 12A, 13A, 14A and 12B, 13B, 14B before being reeled up at 66a, or coated at 67, dried at 68, further glossed at 69 and fed to a reel (not shown). The length of each nip, in the machine direction, is preferably less than one inch. In another embodiment (Fig. 4, not shown), the web passes round fly-rolls between the two nips of each press.