Patent GB-810575-A (GB)
Title: Aqueous coating compositions and coated substrates
IPC: D21H19/22
Filed: 1957-02-13
Abstract: An aqueous composition for coating fibrous substrates comprises (1) from 10 to 35 parts (by weight) of an ammonium salt of an approximately 1 : 1 mol. ratio copolymer of maleic anhydride and diisobutylene, the salt having an average molecular weight of 500 to 5000; and (2) 90 to 65 parts of a water-insoluble linear addition polymer having a Ti value not over 30 DEG  C.  The Ti value is the transition or inflection temperature found by plotting the modulus of rigidity against temperature and is that determined at 300 kg./cm.2. The diisobutylene used is 2 : 4 : 4-tri-methyl-1-pentene.  The ammonium salt of the copolymer may either be a simple salt or a complex zinc ammonium salt which can be made by adding ammonium hydroxide to a solution of zinc acetate or other water-soluble zinc salt, redissolving the Zn(OH)2 formed by adding further ammonium hydroxide, and adding the resulting solution to an aqueous dispersion of the copolymer in the form of its ammonium salt.  The aqueous dispersion of component (2) may be made by conventional emulsion polymerization or copolymerization of one or more monomers which form polymers or copolymers having the desired Ti value.  Monomers which form sufficiently soft homopolymers include the acrylates of primary and secondary alcohols having from 1 to 18 C atoms and methacrylates of alcohols having 5 to 18 C atoms; these monomers may be copolymerized with one another or with hardening comonomers such as the alkyl (of 1-4 C atoms) methacrylates, styrene, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, and vinylidene chloride, and a list of suitable proportions of these comonomers is given; copolymers of 35 to 65 per cent (by weight) of butadiene with 65 to 35 per cent of acrylonitrile or styrene are also suitable.  The emulsifying agents used may be anionic and/or non-ionic, e.g. anionic-higher fatty alcohol sulphates, alkaryl sulphonates, alkali metal, higher alkyl sulphosuccinates and alkali metal salts of alkarylpolyethoxyethanol sulphates or sulphonates; non-ionic-alkylphenoxypolyethoxy-ethanols, polyethoxyethanol derivatives of methylene-linked alkylphenols; condensates of ethylene oxide with higher alkyl mercaptans, or with alkylthiophenols; ethylene oxide derivatives of long-chain fatty acids, of long-chain fatty alcohols, of etherified or esterified polyhydroxy compounds having an hydrophobic hydrocarbon chain or of long or branched chain amines; and block copolymers of ethylene and propylene oxides; many examples of these emulsifying agents are given.  Instead of using the above emulsifying agents, the copolymer salt (1) may be used.  In examples there is disclosed the preparation of aqueous dispersions of the ammonium or complex zinc ammonium salt of maleic anhydride-diisobutylene copolymer and a copolymer of (1) 66 per cent (by weight) of ethyl acrylate and 34 per cent of methyl methacrylate; (2) 75 per cent of vinyl acetate, 15 per cent methyl acrylate and 10 per cent of ethyl acrylate; (3) 60 per cent of butadiene and 40 per cent of styrene; and (4) 65 per cent of ethyl acrylate, 33 1/2 per cent of methyl methacrylate and 1 1/2 per cent of methacrylic acid. The compositions may be applied to the substrates, e.g. by a knife coater, dipping, roller-coating, spraying or brushing, with subsequent drying of the coated substrates.  Uses.-The compositions may be used for coating papers, e.g. bond writing paper, paperboards, e.g. cardboard, chipboard and carton stock, wrapping papers or boards, or liners for containers intended for packaging of foods, greases, chewing gum, soap, soap powders, cosmetics or caulking compounds; the coated papers may also be used for lining drawers and shelves and as book-covers or book pages; the compositions may also be applied directly over hydrophobic inks, such as may be on decorated or printed paper or cardboard, e.g. postcards, magazine covers or wallpapers, or they may be applied to photographs or to building construction papers or boards, e.g. plasterboard; they may also be used as release coatings on paper to be used as liners in concrete moulds or for covering freshly-laid concrete roads. Specification 753,066, [Group VIII], is referred to.