Patent GB-816653-A (GB)
Title: Improvements in or relating to isocyanate based polymers
IPC: C08G18/69
Filed: 1956-09-10
Abstract: The invention comprises a segmented polyurethane polymer consisting essentially of units of the formula <FORM:0816653/IV (a)/1> wherein G is a bivalent radical obtained by removing the terminal hydrogen atoms from a polyalkylene-ether glycol, a polyalkylene-arylene ether glycol, a polyhydrocarbon glycol, a polyalkylene ether thioether glycol or a polyalkylene-arylene ether thioether glycol of molecular weight at least 750; B is a bivalent organic radical which is inert to isocyanate groups; R is a carbonyl group, a non-polymeric diacyl radical or a polymeric hydrocarbon diacyl radical (with the proviso that when R is a polymeric hydrocarbon diacyl radical of molecular weight at least 748, G is not a polymeric hydrocarbon glycol radical); the said polymer containing segments of molecular weight at least 748 (represented by G and optionally R and/or a polymeric connecting group) of at least two different classes, no one class accounting for more than 95 mol. per cent of the total; at least 60 per cent of the total weight of the polymer being made up of polymeric radicals.  Segments are regarded as being of different classes when they have chemical structures of different types, e.g. radicals G derived from different polyalkylene ether glycols are of the same class, but such a radical and those derived from a polyalkylene-arylene ether glycol, a polyhydrocarbon glycol, a polyalkylene ether thioether glycol or a polyalkylene-arylene thioether glycol each represents a different class.  The polymers are prepared by reacting in appropriate proportions mixtures of the corresponding glycols and organic diisocyanates or isocyanate terminated polymers or mixtures of the corresponding bischloroformates of glycols and primary diamines.  A polymeric glycol providing one of the polymeric segments may be reacted with a diisocyanate and the resulting isocyanate terminated prepolymer is then chain-extended with another compound providing a polymeric segment which contains a plurality of active hydrogen atoms capable of reacting with isocyanates and in which no more than two atoms in the molecule have active hydrogen attached thereto.  Alternatively, two or more polymeric glycols of at least two different classes are simultaneously or successively reacted with a diisocyanate and the resulting isocyanate-terminated prepolymer is chainextended with a non-polymeric compound which contains a plurality of active hydrogen atoms capable of reacting with isocyanates and in which no more than two atoms in the molecule have active hydrogen attached thereto. Reaction may be effected in solvent medium, for example dimethylformamide or tetrahydrofuran.  Chain extension can be controlled by the addition of amines as in Specification 791,853. The polymeric glycols may be those employed in the process of Specifications 791,854, 796,041 and 816,651.  Suitable polyhydrocarbon glycols or amines may be prepared by polymerizing ethylenically unsaturated hydrocarbons in the presence of compounds which furnish terminal hydroxyl or amino groups.  For example isoprene may be polymerized in the presence of 2,21-azo-bis-isobutyronitrile, the resulting polyisoprene dinitrile being converted to the corresponding diamine.  As non-polymeric chain-extending agents there may be used water, hydrogen sulphide, ethylene glycol, hexamethylene glycol, adipic acid, terephthalic acid, adipamide, 1,2-ethanedithiol, hydroquinone, ethanolamine, 4-aminobenzoic acid, m-phenylenediamine, propylenediamine, 4-aminobenzamide, sulphanilamide, aminopropionic acid, 1,4-cyclohexanedisulphonamide, 1,3-propanedisulphonamide, 4-hydroxybenzoic acid, p-aminophenol, ethylenediamine, succinic acid, succinamide, 1,4-butanedisulphonamide, 2,4-tolylene-diamine, bis(4-aminophenyl)methane, b -hydroxypropionic acid and 1,2-ethanedisulphonic acid.  The reaction may be controlled by adding small amounts of an acid reacting compound or accelerated by the presence of the acid salt of an organic tertiary nitrogen or phosphorus base as described in Specification 731,071.  The elastomers prepared can be cured by mixing on a rubber mill with a polyisocyanate followed by curing at elevated or room temperatures. Alternatively, when the polymer contains an unsaturated hydrocarbon segment, sulphur-curing agents can be employed.  In examples: (1) a thiodiglycol/butanediol copolymer is reacted with toluene-2,4-diisocyanate to give a prepolymer which is further reacted with a polyisoprene diamine.  The polymer obtained is cured with 1,3-bis(3-isocyanato-p-tolyl)urea; (2) a mixture of a polyether-thioether glycol and polytetramethylene-ether glycol is reacted with toluene-2,4-diisocyanate to give a polyurethane with terminal OH groups.  This is reacted with further diisocyanate, the prepolymer obtained is chain-extended with water and the resulting polymer is cured with mercaptobenzimidazole and 1,3-bis-(3-isocyanato-p-tolyl)urea.  A number of generally similar examples are given using the starting materials, and also compounds prepared as described below.  A saturated polyisoprene diamine is prepared by reacting isoprene and 2,21-azo-bis-isobutyronitrile under pressure and reducing the -CN terminated polyisoprene with Raney nickel.  In a similar process lithium aluminium hydride is the reducing agent.  A polyether-thioether glycol is prepared by heating HOC2H4-S-CH2CH(CH3)-CH2OH in xylene in the presence of p-toluene sulphonic acid.  A polyalkylene-arylene ether glycol is prepared by reacting polytetramethylene-ether glycol and a ,a 1-dibromo-p-xylene in the presence of potassium hydroxide.  A polyether-thioether glycol is prepared by condensing thiodiglycol and butane-1,4-diol.  The polymers may incorporate as additional compounding agents carbon black, clay, silica, esterified silica particles, talc, zinc and magnesium oxides, calcium and magnesium carbonates, titanium dioxide, plasticisers and colouring agents. Specification 811,725 also is referred to.