Patent GB-1305452-A (GB)
IPC: D21H11/16
Filed: 1970-02-12
Abstract: 1305452 Fibres of mixed compositions TOMOEGAWA PAPER MFG CO Ltd 12 Feb 1970 [12 Feb 1969] 6915/70 Heading B5B [Also in Divisions C3 and D2] Mixed fibres of cellulose and synthetic polymer or fibres of a graft-polymer on a cellulose substrate are used to make electrically insulating paper. The fibres are made by dissolving cellulose in a mixed solvent comprising: (a) an organic solvent, SO 2  and an amine, or (b) an organic solvent and nitrogen dioxide, or (c) an organic solvent and nitrosyl chloride, or (d) an organic solvent and anhydrous chloral, or (e) liquid SO 2  and an amine, mixing the solution with a solution or suspension of one or more synthetic polymers, and regeneratively solidifying, e.g. by extrusion, the mixed solution or suspension, or by dissolving the graft polymer in one of the mixed solvents, optionally adding a solution or suspension of a synthetic polymer and regeneratively solidifying this solution. In either case, the product is treated to yield a pulp-like or granular substance suitable for processing into paper. The synthetic polymer may be a polycarbonate, polyphenylene oxide, polysulphone, polystyrene, cross-linked polyethylene, polytetrafluorethylene, polytrifluorochlorethylene, polypropylene, polyacetal, poly - 4 - methylpentene - 1, polyvinylcarbazole, polyester or copolymer of fluorethylene and propylene. If a graft polymer is used, the grafted chains may be derived from styrene, another vinyl monomer or a silicone. The cellulose used may be wood pulp, cotton linters, depolymerized cellulose or regenerated cellulose. In the examples: (1) to a mixed solvent of N,N-dimethylformamide and dioxane are added unbleached kraft pulp followed by nitrogen dioxide; the mixture is stirred and a solution of polysulphone in dioxane added and stirred in; the solution is extruded into air and the extrudate solidified in water; (2) dimethyl sulphoxide and diethylamine are added to unbleached kraft pulp and well mixed; liquid SO 2  is added and the mixture stirred; polyphenylene oxide is dissolved separately in chloroform and diethylamine and SO 2  added; the polyphenylene oxide solution is added to the cellulose solution and stirred in; the mixed solution is extruded into air and solidified in a bath of water and methanol; (3) unbleached kraft pulp is dispersed in a mixture of formamide, chloroform and diethylamine and gaseous SO 2  is blown in; separately, polysulphone is dissolved in chloroform, and this solution added to the cellulose solution; the mixed solution is extruded into methanol; (4) the mixed solution of Example 3 is extruded into water, and the extrudate then washed in methanol to remove chloroform; (5) the mixed solution of Example 1 is extruded into water and the resulting fibres stretched 250%; (6) polyphenylene oxide, dimethyl sulphoxide, methylene chloride and diethylamine are added to unbleached kraft pulp, SO 2  is added and the mixture cooled to 0‹ C.; the solution is extruded into air at 40‹ C. and the extrudate washed in methanol; (7) cotton linters are dispersed in dimethyl sulphoxide and anhydrous chloral added, finely ground polyphenylene oxide is added to form a suspension which is extruded into water; (8) polycarbonate is dissolved in a mixture of dioxane and N,N-dimethylformamide, and unbleached kraft pulp and NO 2  then added; the solution is filtered and extruded into water; the fibres are stretched 250%; (9) formarnide and diethylamine are added to unbleached kraft pulp, liquid SO 2  is added to dissolve the cellulose and powdered polyethylene, cross-linked by irradiation, is stirred in to form a suspension, which is extruded into water; (10) polystyrene is dissolved in N,N - dimethylformamide, bleached kraft pulp and NOCl are added, and the solution extruded into water in which a propeller is rotated so that short fibres are formed; (11) cotton linters, styrene monomer, water and ceric ammonium nitrate are mixed and heated under nitrogen to obtain a graft polymer, which is dispersed in ethyl acetate; NO 2  is added to dissolve the graft polymer, and the mixture extruded into methanol; the fibres are stretched 200%; (12) styrene is grafted on to cellulose as in Example 11, but in smaller amount; the graft polymer and polysulphone are dispersed in dioxane and NO 2  added to form a solution which is extruded; and (13) polysulphone is dissolved in liquid SO 2 , cotton linters and diethylamine are added and a solution formed; this is extruded into methanol and the extrudate is washed.