Patent GB-1069953-A (GB)
Title: Improvements in treating of paper
IPC: D21H17/19
Filed: 1964-06-11
Abstract: A polymeric resinous material is deposited on a preformed sheet or web of cellulosic paper by polymerizing a monomer in situ.  The polymerization is promoted by free radicals formed by subjecting the paper to a dielectric breakdown, or contacting the paper with a gas in which free radicals have been formed by subjecting the gas to dielectric breakdown.  The paper may be impregnated with the monomer and placed or passed between electrodes between which is a potential difference big enough to cause dielectric breakdown.  Alternatively, the paper may first be subjected to the dielectric breakdown and immediately after brought into contact with the monomer, or a carrier gas may be subjected to dielectric breakdown and then brought into contact with the paper which may be brought into contact with monomer before, during or after the treatment, or the monomer in gaseous form may itself be used as the carrier gas.  The paper may be subjected to two or more successive treatments of this kind, using the same or different monomers, and may be treated with one monomer on one side and a different monomer on the other.  Copolymers may be formed by using mixtures of monomers. The polymer formed may be a graft polymer on the cellulose as substrate.  Monomers referred to are: acrylic acid, its methyl, ethyl, n-butyl, iso-butyl and ethylhexyl esters and nitrile, methacrylic acid, methyl methacrylate, ethylene, tetrafluorethylene, vinyl acetate, vinylidene chloride, styrene, alpha-methylstyrene, vinyl-toluene, ethylene dimethacrylate and divinyl-benzene. The paper treated may be sized or unsized, and may be a filter paper.ALSO:A polymeric resinous material is deposited on a preformed sheet or web of cellulosic paper by polymerizing a monomer in situ.  The polymerization is promoted by free radicals formed by subjecting the paper to a dielectric breakdown, or contacting the paper with a gas in which free radicals have been formed by subjecting the gas to dielectric breakdown.  The paper may be impregnated with the monomer and placed or passed between electrodes between which is a potential difference big enough to cause dielectric breakdown.  Alternatively the paper may first be subjected to the dielectric breakdown and immediately after brought into contact with the monomer, or a carrier gas may be subjected to dielectric breakdown and then brought into contact with the paper which may be brought into contact with monomer before during or after the treatment, or the monomer in gaseous form may itself be used as the carrier gas.  The paper may be subjected to two or more successive treatments of this kind, using the same or different monomers, and may be treated with one monomer on one side and a different monomer on the other.  Copolymers may be formed by using mixtures of monomers.  The polymer formed may be a graft polymer on the cellulose as substrate.  Monomers referred to are: acrylic acid, its methyl, ethyl, n-butyl, iso-butyl and ethylhexyl esters and nitrile, methacrylic acid, methyl methacrylate, ethylene, tetrafluorethylene, vinyl acetate, vinylidene chloride, styrene, alpha-methyl-styrene, vinyl-toluene, ethylene dimethacrylate and divinyl-benzene.  In one Example, paper having a copolymer of divinylbenzene and styrene formed within it is extracted with toluene; a residue remained in it which rendered it water-repellent. The paper treated may be sized or unsized, and may be a filter paper.