Improvements in or relating to the grafting of polymers to cellulose substrates

摘要

In grafting an ethylenically unsaturated monomer on to a cellulose substrate and polymerizing in situ with high energy ionising radiations, the substrate is swelled prior to irradiation with a water-soluble non-polymerizable swelling agent and irradiated with at least 0,001 watt-sec/cm2 of ionising radiation with an energy equivalent of an electron beam of at least 0,1 Mev. The substrate may be in contact with the monomer during or after the radiations in the latter case the substrate remains active for a longer period if stored at low temperature in an inert atmosphere. The substrate may be of regenerated cellulose and in the form of a film, filament, fabric, extrusion moulding or tube or of native cellulose e.g. wood, wood-pulp, paper, cotton or vulcanised fibre-board. Swelling agents specified are aqueous solutions of acids, bases and salts, thioures, chloral hydrate, resorcinol, benzene sulphonates, glycerol and ammonium sulphamate; water itself; ethanol, ZnCl2-methanol, glycerol, glycerol-toluene and glycerol-urea; and mixtures thereof: they are preferably incorporated at 0-50 DEG C. as liquids, usually by soaking, but may be incorporated as vapours. In addition, a softener e.g. glycerol may be present in the swelling agent (see U.S.A. Specifications 2,074,336, 2,074,349, 2,087,008 and 2,328,679) and the cellulosic material may be treated with an anchoring agent resin e.g. a urea-aldehyde, phenol-formaldehyde, ketone aldehyde, amine- or alcohol-modified urea-formaldehyde resin (see Specifications 593,947, 593,947 and 684,105 and U.S.A. Specifications 2,159,007 and 2,564,575) or with an organic titanium compound (see Specifications 772,675, 777,584 and 814,201). Specified monomers are acrylic and methacrylic acids, esters, nitriles and amides (acrylonitrile, glycidyl methacrylate, methylmethacrylate); vinyl and vinylidene halides (vinyl chloride, vinyl fluoride, vinylidene chloride and vinylidene fluoride); vinyl carboxylates (vinyl acetate, vinyl trimethyl acetate); vinyl aryls (styrene and vinyl naphthalene); other vinyl derivatives (methyl vinyl ketone, vinyl isobutyl ether, vinyl ethyl ether); olefines (ethylene, isobutylene); and mixtures of ethylenically unsaturated monomeric compounds (ethylene/vinyl chloride, acrylonitrile/isobutylene, ethylene/vinylacetate, isobutylene/vinlacetate, vinylacetate/alkylidene diacetate vinyl acetate/vinyl methyl ether). The preferred ethylenically unsaturated monomers have the formula: >C = CH2 where R is selected from the group consisting of (a) the halogens, (b) where R2 may be H, or an alkyl or aryl group, (c) -CN, (d) where R3 is an alkyl or aryl group, and (e) -OR4, where R4 is an alkyl or aryl group, and R1 is H, a halogen, or an alkyl or aryl group. Vinyl-phosphorus monomers (bis (chloroethyl) vinyl phosphonate) may be employed to impart flameproof properties; vinyl silane monomers (vinyl-dimethyl-chlorosilane, vinyl-ethoxy-dimethyl silane) may be employed to give waterproofing properties; acrylonitrile gives products resistant to mildew and fungi and, when used in conjunction with vulcanised fibreboard, increased electrical resistance suitable for use with printed circuits. Specified radiations are accelerated electrons, protons, neutrons, alpha particles, deuterons and beta particles, X-rays and gamma rays. Preferably radiation having an energy equivalent to an electron beam of 0,75-5 Mev is employed, for an exposure up to a 1,000 watt-sec/cm2, but generally not more than 125 watt-sec/cm2. After irradiation the swelling agent may be removed, e.g. by means of a solvent, heat or vacuum.ALSO:In grafting an ethylenically unsaturated monomer on to a cellulose substrate and polymerizing in situ with high energy ionising radiations, the substrate is swelled prior to irradiation with a water-soluble non-polymerizable swelling agent and irradiated with at least 0.001 watt-sec/cm2 of ionising radiation with an energy equivalent of an electron beam of at least 0.1 Mev. The substrate may be in contact with the monomer during or after the radiation: in the latter case the substrate remains active for a longer period if stored at low temperature in an inert atmosphere. The substrate may be of regenerated cellulose and in the form of a film, filament, fabric, extrusion moulding or tube or of native cellulose e.g. wood, wood-pulp, paper, cotton or vulcanised fibre-board. Swelling agents specified are aqueous solutions of acids, bases and salts, thiourea, chloral hydrate, resorcinol, benzene sulphonates, glycerol and ammonium sulphamate; water itself; ethanol, ZnCl2-methanol, glycerol, glycerol-toluene and glycerol-urea; and mixtures thereof: they are preferably incorporated at 0-50 DEG C. as liquids, usually by soaking, but may be incorporated as vapours. In addition, a softener e.g. glycerol may be present in the swelling agent (see U.S.A. Specifications 2,074,336, 2,074,349, 2,087,008 and 2,328,679) and the cellulosic material may be treated with an anchoring agent resin e.g. a urea-aldehyde, phenol-formaldehyde, ketone aldehyde, amine- or alcohol-modified ureaformaldehyde resin (see Specifications 593,947, 684,105 and U.S.A. Specifications 2,159,007 and 2,564,575) or with an organic titanium compound (see Specifications 772,675, 777,584 and 814,201). Specified monomers are acrylic and methacrylic acids, esters, nitriles and amides (acrylonitrile, glycidyl methacrylate, methylmethacrylate); vinyl and vinylidene halides (vinyl chloride, vinyl fluoride, vinylidene chloride and vinylidene fluoride); vinyl carboxylates (vinyl acetate, vinyl trimethyl acetate); vinyl aryls (styrene and vinyl naphthalene); other vinyl derivatives (methyl vinyl ketone, vinyl isobutyl ether, vinyl ethyl ether); olefines (ethylene, isobutylene); and mixtures of ethylenically unsaturated monomeric compounds (ethylene/vinyl chloride, acrylonitrile/isobutylene, ethylene/vinylacetate, isobutylene/vinylacetate, vinylacetate/allylidene diacetate, vinyl acetate/vinyl/methyl ether). The preferred ethylenically unsaturated monomers have the formula: where R is selected from the group consisting of (a) the halogens, (b) where R2 may be H, or an alkyl or aryl group, (c) -CN, (d) where R3 is an alkyl or aryl group, and (e) -OR4 where R4 is an alkyl or aryl group, and R1 is H, a halogen, or an alkyl or aryl group. Vinyl-phosphorus monomers (bis (chloroethyl) vinyl phosphonate) may be employed to impart flameproof properties; vinyl silane monomers (vinyldimethyl-chlorosilane, vinyl-ethoxy-dimethyl silane) may be employed to give waterproofing properties; acrylonitrile gives products resistant to mildew and fungi and, when used in conjunction with vulcanised fibreboard, increased electrical resistance suitable for use with printed circuits. Specified radiations are accelerated electrons, protons, neutrons, alpha particles deuterons and beta particles, X-rays and gamma rays. Preferably radiation having an energy equivalent to an electron beam of 0.75-5 Mev is employed, for an exposure up to a 1000 watt-sec/cm2, but generally not more than 125 watt-sec/cm2. After irradiation the swelling agent may be removed, e.g. by means of a solvent, heat or vacuum.