Patent GB-796042-A (GB)
Title: Improvements in or relating to the preparation of curable polyurethane-urea elastomers
IPC: C08L75/00
Filed: 1954-10-19
Abstract: Curable elastomers containing urethane and urea linkages are prepared by agitating together in aqueous medium, an acid acceptor, 1 mol. of a bis-chloroformate of molecular weight at least 875, 0.15-20 mols. of phosgene and 0.3-2 mols. of a diamine per mol. of bis-chloroformate and phosgene.  Suitable bis-chloroformates are prepared by reacting excess phosgene with a polyalkylene ether especially polytetramethylene ether, a polyalkylene ether glycol which also contains arylene or cycloalkylene radicals (e.g. a condensate of a polyalkylene ether glycol with a ,a 1-dibromo-p-xylene) a polyalkylene ether-thioether glycol (e.g. a co-condensate from a glycol and a thioglycol), a hydroxyl-terminated polyester, or a hydroxyl-terminated hydrocarbon or halohydrocarbon polymer (e.g. obtained by polymerization in presence of free radicals such as aliphatic azo dinitriles or dicarboxylates of butadiene, isoprene or 2-chlorobutadiene, or co-polymerization of styrene or iso-butylene with a diene).  Typical suitable diamines are tolylenediamines, phenylenediamines, ethylenediamine, tetramethylenediamine, decamethylene-diamine, cyclohexyldiamine, 4,41-methylene-bis-(phenylamine) 1,5-diaminonaphthalene, and diaminopyridine.  The diamines may be employed as hydrohalides.  All three reactants may be reacted simultaneously or the diamine first with one of the others, but preferably the phosgene-bis-chloroformate mixture if desired in solution, e.g. in toluene, xylene or benzene, is added to an aqueous solution or suspension of the diamine.  A bis-chloroformate prepared with excess phosgene from a dihydric body may contain sufficient phosgene for use in the process directly or phosgene may be added to the desired molar ratio.  Suitable acid-acceptors are sodium hydroxide, sodium acetate or sodium borate. An acid-stable emulsifying agent, e.g. long chain alkyl sodium sulphates or phosphates, alkyl-aryl sulphonates, lignin sulphonate, or ethylene oxide-long chain alcohol or -fatty acid adducts are preferably present.  Without an emulsifying agent vigorous agitation, e.g. in a homomixer, is required.  The product separates as a loose elastomeric mass which is washed on a rubber wash mill and dried on a drying mill.  The products are curable, preferably with di-isocyanates, e.g. 2,4-tolylene diisocyanate or its dimer, or bis-(3-isocyanate-4-methylphenyl) urea-MgO, carbon black, silica, plasticizers and usual compounding ingredients may be added. Several examples are given mostly employing a bis-chloroformate of polytetramethylene glycol made from tetrahydrofuran.  A variety of amines are employed and curing is effected with di-isocyanates. Example (10) starts with a polypropylene ether glycol; Example (12) with a polyethylene ether glycol; Example 13 with a glycol of formula <FORM:0796042/IV (a)/1> when x = 13 or 14; Example (14) with a product obtained by condensing thiodiglycol and 1,4-butanediol in presence of p-toluene sulphonic acid, and Example (16) with an hydroxyl terminated polyester from 1,4-butanediol and adipic acid. In Example (15) 2-chlorobutadiene-1,3 is polymerized by heating in toluene with diethyl-2,21-azobis-(isobutyrate).  The product dissolved in ether is treated with lithium aluminium hydride. After treating with acid a polychloroprene glycol is formed which is a suitable starting material for a bis-chloroformate for use in the process of the invention.  More than one diamine and more than one chloroformate may be used in admixture.  The products are useful as elastomers.  Specifications 731,071 and 796,041 are referred to.