Patent GB-811725-A (GB)
Title: Curable polymers
IPC: C08L75/00
Filed: 1955-08-26
Abstract: Curable polymers comprise structural units of formula: <FORM:0811725/IV (a)/1> wherein L is a bivalent polymeric radical having molecular weight of 588 to 11,966 and having a carbon skeleton formed by the polymerization of ethylenically unsaturated hydrocarbon or halogen-substituted hydrocarbon monomer at least 50 per cent of which is a conjugated diene, B is a bivalent organic radical inert to isocyanate groups, X is a carbonyl or sulphonyl radical or <FORM:0811725/IV (a)/2> radical wherein the terminal oxygen is attached to L, Q is a carbonyl radical or a non-polymeric diacyl radical, m is an integer greater than zero and n is an integer including zero, each of said units being connected to the next by a radical Q, the overall ratio of the number of B to L radicals in the polymer being between 1.1 : 1 and 12 : 1, and at least 35 per cent of the total weight of the polymer being the radicals L.  The polymers may be prepared by mixing, optionally in the presence of a solvent, e.g. heptane or octane: (1) a long-chain bifunctional compound, e.g. terminating in carboxyl, sulphonic acid or hydroxyl groups; (2) an organic diisocyanate and (3) a chain extender.  The diisocyanate may be reacted first with the long chain compound or the chain exteWder, or simultaneously with both, preferably in the presence of a catalyst, e.g. a salt of an organic tertiary nitrogen or phosphorus base, such as pyridine. The reaction may be carried out in solution in dimethyl formamide, tetrahydrofuran or dioxane and the product recovered by evaporation, e.g. as a film or coating, when chain extension may occur by reaction with moist air.  Alternatively the long chain diols may be reacted with phosgene in solution in toluene, and then in aqueous solution in the presence of an acid acceptor with more phosgene and a primary diamine, e.g. 2,4-tolylenediamine or m-phenylenediamine.  Specified diisocyanates are 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m - phenylene diisocyanate, 4 - chloro - 1,3 - phenylene diisocyanate, 4,41-biphenylene diisocyanate, 1,5-naphthylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,10 - decamethylene diisocyanate, 1,4 - cyclohexylene diisocyanate, 4,41 - methylene - bis - (cyclohexyl isocyanate), 1,5 - tetrahydronaphthalene diisocyanate and di-(3-isocyanato-4-methylphenyl)urea or their reaction products with phenols or related mercapto compounds. Specified chain extenders are water, hydrogen sulphide, ethylene glycol, hexamethylene glycol, diethylene glycol, adipic acid, terephthalic acid, adipamide, 1,2-ethanedithiol, hydroquinone, monoethanolamine, 4-aminobenzoic acid, m-phenylene diamine, propylene diamine, 4-aminobenzamide, sulphanilamide, aminopropionic acid, 1,4-cyclohexanedisulphonamide, 1,3-propanedisulphonamide, 4-hydroxybenzoic acid, p-aminophenol, ethylene diamine, succinic acid, succinamide, 1,4-butanedisulphonamide, 2,4 - tolylenediamine, bis - (4 - aminophenyl)methane, b -hydroxypropionic acid and 1,2-ethane-disulphonic acid.  When water or a carboxylic or sulphonic acid is used, carbon dioxide is evolved and may be retained to give a porous product.  The long-chain diols may be prepared by polymerizing ethylenically unsaturated monomers, e.g. butadiene, isoprene, 2,3-dimethyl butadiene, chloroprene, fluoroprene, bromoprene and optionally styrene, in the presence of (a) an aliphatic azo dicarboxylate in which the carbon atoms attached to the nitrogen are tertiary, e.g. diethyl-2,21-azo-bis-isobutyrate or 2,21 - azo - bis - 4 - carboxy - 2 - methylbutyronitrile, and reducing the product with lithium aluminium hydride or (b) hydrogen peroxide, e.g. in emulsion with abietyl amine, dextrose, ferrous sulphate, hydrogen peroxide and adding a terminating agent such as tetramethylthiuram disulphide. The polymer chains may be hydrogenated, e.g. in the presence of a Raney nickel or palladium/charcoal catalyst, or the unsaturation protected by adding an antioxidant or working in the absence of air. The polymeric products containing excess diisocyanate may be stabilized against premature cure by adding a primary or secondary nitrogen base, e.g. piperidine, and may be cured, preferably mixed with magnesium oxide, by milling and heating under pressure with residual or added polyisocyanate, e.g. as above or 3,31-diisocyanato - 4,41 - dimethyl carbanilide. Elastomeric products containing unsaturated chains may be vulcanized, e.g. by heating with sulphur, zinc oxide, stearic acid, salicyclic acid and tetramethyl thiuram monosulphide. Carbon black, clay, silica, talc, calcium and magnesium carbonates, titanium dioxide, plasticizers and colouring agents may be added before curing.  Solutions or dispersed gels of the uncured elastomers may be used to give films, coatings and adhesive bonds between plastics, elastomers, fabrics, metals, wood and leather.  The cured elastomers may be emloyed in tyres, inner tubes, belts, hose, wire and cable jackets and footwear.  Sponges, cushions and heat insulators may be prepared by reacting the diol and isocyanate with water in a mould, in the presence of glycerol and triethylamine or pyridine, so that the carbon dioxide formed expands the polymer to fill the mould.