Patent GB-1039826-A (GB)
Title: Improvements in and relating to the coating of base sheets with vinylidene chloride coating compositions
Inventor: BRUNTON JAMES CHARLES
IPC: C08F214/08
Filed: 1964-08-18
Abstract: Vinylidene chloride copolymer solutions which may be applied to base sheets to give on drying moisture-proof coatings are prepared by copolymerizing in the presence of an initiator a mixture of at least 80 weight per cent of vinylidene chloride and at least one ethylenically unsaturated comonomer in a volatile solvent for the copolymer in amount of less than 100% by weight of the monomers, separating unreacted vinylidene chloride from the reaction product and adjusting the solvent content of the reaction product as required to form a coatable solution. Specified comonomers are acrylonitrile, methacrylonitrile, vinyl chloride, vinyl acetate and alkyl esters of acrylic and methacrylic acids. An acidic monomer, e.g. citraconic or itaconic acid or anhydride, or mesaconic, acrylic or methacrylic acid may also be present. The preferred initiator is azo diisobutyronitrile.  Specified solvents are methyl ethyl ketone, dioxane, dimethyl formamide and tetrahydrofuran, which may be used with diluents, e.g. benzene, toluene and xylene.  The coating solutions may also comprise slip and antiblocking agents, e.g. solid ketones and finely divided vinyl chloride polymers and organic derivatives of hydrous aluminium silicates; and may be applied to cellulose and synthetic polymer films, paper, cardboard, fabrics and leather.  In examples, coating solutions are prepared by copolymerizing vinylidene chloride and acrylonitrile in (1) methyl ethyl ketone and toluene, (2) tetrahydrofuran and (5) tetrahydrofuran with addition of further tetrahydrofuran during the reaction; and by copolymerizing vinylidene chloride, acrylonitrile and itaconic acid in (3) and (4) tetrahydrofuran.  The reaction products are converted to coating solution by adding hydrogenated castor oil and finely divided silica together with addition solvents (1) methyl ethyl ketone and toluene and (2)-(5) tetrahydrofuran and toluene.ALSO:Flexible substrates may be coated with compositions prepared by copolymerising a mixture of at least 80 weight per cent of vinylidene chloride and at least one ethylenically unsaturated comonomer in the presence of a volatile solvent for the resulting copolymer in amount of less than 100 per cent by weight of the monomers, separating unreacted vinylidene chloride from the reaction product and adjusting the solvent content of the reaction product as required to form a coatable solution. Specified substrates are cellulose, polyethylene and polypropylene films, paper, woven and non-woven fabrics and leather.  The compositions may also comprise slip and anti-blocking agents, e.g. laurone, finely divide vinyl chloride polymers and organic derivatives of hydrous aluminium silicates.  In examples regenerated cellulose films incorporating urea/formaldehyde resin anchoring agents are coated with coating compositions comprising hydrogenated castor oil, finely divided silica and toluene together with vinylidene chloride/acrylonitrile copolymers and (1) methyl ethyl ketone or (2 and 5) tetrahydrofuran, or together with (4 and 5) vinylidene chloride/acrylonitrile/itaconic acid copolymers and tetrahydrofuran.