Patent GB-1050922-A (GB)
IPC: D06M14/18
Abstract: 1,050,922. Polymerization on fibrous materials. DUNLOP RUBBER CO. Ltd. Aug. 2, 1963 [Aug. 22, 1962], No. 32167/62. Heading C3G. [Also in Division D1] Fibrous material in the form of unwoven loose or felted fibrous webs is bonded by exposure to the vapour of a polymerizable monomer the fibres having been previously treated so as to cause polymerization of the monomer. Preferably the fibrous material is maintained at a temperature above the vaporization temperature of the monomer and is isolated from any condensate or liquid monomer. Suitable fibres include cellulosic, protein, hydrocarbon, polyester, polyamide, polyurethane, polyvinyl and inorganic fibres. Particularly useful results are obtained with nylon 66, nylon 6, polyethylene terephthalate, polyethylene, polypropylene, polyvinyl alcohol and rayon fibres. The fibres may be curled, crimped, monofil, staple or fibrillar. Treatment of the fibres to ensure polymerization may be by oxidation with hot air, oxygen, chromic or nitric acid, by ozonization, by swelling the fibres in spontaneously peroxidizing liquids or vapours, such as cumene, or by treating the fibres with polymerization initiators and/or catalysts such as cumene hydroperoxide, lauryl hydroperoxide, azodiisobutyronitrile, various persulphates, polyamines, such as tetraethylene pentamine and redox systems or their components. such as ferric and ferrous acetonyl-acetonate. Exposure of the fibrous material to gamma irradiation before or during the vapour treatment or to ultra-violet light irradiation during the treatment assists polymerization. The polymerization initiator is preferably non-volatile in order to prevent wasteful polymerization elesewhere than on the fibres. Vinyl monomers are preferred and a suitable non-volatile initiator for such compounds is benzoyl peroxide. Among suitable monomeric compounds are acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile, vinyl acetate, styrene, methyl vinyl ketone, vinyl methyl ether, vinyl pyridine and vinyl isocyahate. Mixtures of monomers may be used to produce deposition of copolymers, and to promote cross-linking a difunctional monomer, such as divinyl-benzene, may be incorporated in the mixture. Non-volatile polymerization inhibitors may be included with the boiling monomer to prevent any polymerization occurring in the body of liquid monomer. Where the polymer is thermoplastic and has a lower transition temperature than the fibres hot pressing may be used to densify the fabric after the bonding treatment. In Example I crimped rayon yam of 6 denier filaments was cut to 1<SP>7</SP>/16 inches staple and teased to form an even mass which was then needle-punched. The resulting felt of 40 grammes weight was sprayed with 25 grammes of a 5% solution of benzoyl peroxide in methylethyl ketone, mangled and allowed to dry off at room temperatures. After drying, the felt was laid on a horizontal steel grid fixed in a steel reactor vessel fitted with a reflux condenser and surrounded by a heating jacket maintained at 95‹ C. About 200 grammes of methyl acrylate in which 1 gramme of tertiary butyl catechol had been dissolved was boiled gently in the reactor vessel to bathe the felt in vapour for one hour with the felt at a temperature of 90‹ C. Following this the felt was allowed to cool in air for twenty-four hours when it was found to have picked up 100% of its own weight of polymer. In Example II the monomer was boiled at 100‹ C. and the felt was maintained at 110‹ C. In other examples the fibres treated were relaxed nylon 66 monofils and polypropylene staple fibres; monomers employed were methyl methacrylate, a mixture of equal weights ethyl acrylate and methyl methacrylate, a mixture of equal weights of methyl acrylate and acrylonitrile, and acrylic acid monomer. Products of the invention may be used for non- woven fabrics, artificial leathers, filters, sound and heat-insulating wraps, resilient paddings, upholstery toppings, carpet backings, impregnated gaskets, scouring pads &c.