Patent GB-1065031-A (GB)
Title: Heat-curable thermosetting compositions
IPC: C08K5/06
Filed: 1964-05-28
Abstract: Heat - curable thermosetting compositions comprise (a) a linear water-insoluble copolymer of monoethylenically unsaturated molecules comprising 2 to 50 mol per cent of a hydroxyalkyl ester of an a ,b -monoethylenically unsaturated carboxylic acid having at least 2 carbon atoms between the ester linkage and any hydroxyl group and (b) at least one acetal or ketal which breaks up at the ether oxygen atoms, liberating, at a temperature of from 140 DEG  to 450 DEG  F., an alcoholic product and a sufficient amount of a carbonyl compound to cure the polymer.  The preferred acetals and ketals correspond to the formula <FORM:1065031/C3/1> in which R0 and R2 each represent H or a C1-C10 hydrocarbon radical, R and R1 each represent a C1-C8 alkyl, cyclohexyl or C7-C10 aralkyl group, A is a polyvalent radical selected from C1-C10 aliphatic hydrocarbon radicals optionally substituted by phenyl or alkoxy groups, phenylene radicals optionally substituted by from 1 to 4 alkyl substituents having 1 to 4 carbon atoms or C4-C10 alkylene radicals interrupted by 0 or 5 atoms, and n is an integer of from 2 to 4.  The ester component of the copolymer may be derived from acrylic, methacrylic, crotonic, maleic or fumaric acid and may contain more than one hydroxy substituent in the alkyl group; mixtures of these esters may be present in the copolymer.  An unsaturated acid, such as maleic, fumaric, aconitic, citraconic, crotonic, itaconic, acrylic or methacrylic acid is preferably included as a copolymerized component of the copolymer; components derived from monomers such as acrylic or methacrylic acid esters of cyclohexanol, benzyl alcohol or C1-C18 alkanols, acrylonitrile, methacrylonitrile styrene, vinyltoluene, acrylamide, methacrylamide, N-methylolacrylamide, vinylidene chloride, vinyl chloride and vinyl acetate may also be present. The copolymers may be prepared by solution or emulsion polymerization with initiators such as azo compounds, peroxy compounds, e.g. t.-butyl peracetate, benzoyl peroxide, t.-butyl hydroperoxide or cumene hydroperoxide, redox catalysts, e.g. potassium persulphate/ferrous sulphate/sodium hydrosulphite or potassium persulphate/sodium metabisulphite, and, if desired, a chain transfer agent.  Pigments, extenders, curing catalysts &c. may be added to the resulting product.  In solution polymerization the acetal or ketal is added subsequently while in emulsion polymerization the acetal or ketal is added before polymerizing. When an alcohol is used as part or all of the solvent in solution polymerization, the acetal or ketal may be formed in situ by reacting the alcoholic solvent with a suitable aldehyde or ketone. Before application of the curable compositions an acidic catalyst is introduced. Zinc perchlorate is preferred for this purpose; other catalysts specified are boron trifluoride, ammonium nitrate, ammonium chloride, zinc fluoborate, chloride, bromide or iodide, and inorganic acids having an ionization constant greater than 10-3.  Pigments which may be incorporated in the compositions include chrome yellow, Prussian blue, Brunswick green, titanium compounds, which may be extended with e.g. alkaline earth sulphates, zinc sulphides with or without extenders, zinc oxide, antimony oxide and organic pigments or dyes.  Aminoplast, phenoplast, polyepoxide and alkyd resins may also be present.  The curable compositions are suitable for coating a wide variety of substrates (see Division B2).ALSO:Heat-curable thermosetting compositions suitable for coating a wide variety of substrates comprise (a) a linear water-insoluble copolymer of mono-ethylenically unsaturated molecules comprising 2 to 50 mol per cent of a hydroxyalkyl ester of an a ,b -monoethylenically unsaturated carboxylic acid having at least 2 carbon atoms between the ester linkage and any hydroxyl group and (b) at least one acetal or ketal which breaks up at the ether oxygen atoms, liberating, at a temperature of from 140 DEG  to 450 DEG F an alcoholic product and a sufficient amount of a carbonyl compound to cure the polymer.  (For further details of the copolymer and acetal or ketal see Division C3).  The composition is generally applied as a solution in an organic solvent or as an aqueous emulsion and, before application, an acidic catalyst is introduced, e.g. boron trifluoride, ammonium nitrate, ammonium chloride, zinc fluoborate, chloride, bromide or iodide, and inorganic acids having an ionization constant greater than 10-3.  The composition may additionally contain pigments and resins such as aminoplast, phenoplast, polyepoxide and alkyd resins. Suitable pigments include chrome yellow, Prussian blue, Brunswick green, titanium compounds which may be extended with e.g. alkaline earth sulphates, zinc sulphides with or without extenders, zinc oxide, antimony oxide and organic pigments or dyes.  The compositions may be used for coating paper, textiles, leather, wood, ceremics, brick, stone, concrete surfaces and metals, e.g. in the form of tin cans, canisters, stoves and refrigerators; in Examples films are applied onto iron phosphate-treated steel panels, cold-rolled steel and glass. Drying of the coatings may be effected at room temperature or elevated temperatures from 140 DEG  to 220 DEG F.  Curing is then effected by baking at 140 DEG  to 450 DEG F.