MANUFACTURE OF STRIPPABLE WALLPAPER AND STRIPPABLE POSTER PAPER

摘要

1337026 Papermaking ABITIBI PAPER CO Ltd 13 Aug 1971 [28 Sept 1970] 38159/71 Heading D2A A paper base sheet for strippable wallpaper or poster paper is made by simultaneously wetforming a pair of webs, passing them through a press section to bond them together to form the sheet and drying the sheet, the strength of the bond when the sheet is dry being so controlled that one web of the sheet can be stripped from the other. The bond strength is controlled by the pressure in the press section being controlled, by controlled amounts of rosin size being added to the furnish used to form one or both of the webs, and by controlling the refining of the fibre furnish used. The webs are formed on-Fourdrinier wires 14, 16 and are carried by felts 20, 22 to press sections 24 and 26 and they are then passed to a smoothing press 28, a drier 30, and a size press and calenders (not shown). A clay coating may be applied to the sheet to facilitate printing, and after printing the sheet if used for wallpaper is given a clear plastics coating over the print and the unprinted side of the sheet receives a layer of gum. Examples of preferred fibre furnish give percentages of Hardwood Sulphite, Softwood Kraft, Paper Machine Broke and Mill Broke used, and examples of the quantity of rosin size and alum added to the furnish are also given. The amount of rosin size used is such as to give an ink float test result of 400 seconds minimum for the web which will be subject to printing and 800 seconds minimum for the other web, the combined webs having a result of over 1500 seconds. The sheet may be blade-coated during calendering. The bond between the web is such as to give a reading on a Scott Internal Bond tester of 20 to 50 thousands of a footpound per square inch. The printed sheet may be coated by the air-knife method with an enamel coating formed from a water slurry of clay, pigment and binder. The printing is carried out with water based inks applied on a common impression drum from relief patterns on rollers at a plurality of stations. The invention may be used to make gummed strippable labels.