Isocyanate-extended polyoxyalkylene-carboxy-alkylene polymers
A method of preparing a gum stock comprises forming a mixture of oxyalkylene-carboxyalkylene polymers by reacting a diphenol, a diol, a diamine, an amino alcohol, a dimercaptan, a mercapto-alcohol, water or hydrogen sulphide; a lactone of the general formula <FORM:0887180/IV (a)/1> in which n is an integer having a value of at least 2, all the R's are hydrogen when n is 2, at least 6 R's are hydrogen when n is more than 2 and the remaining R's are hydrogen or alkyl, cycloalkyl, alkoxy or single ring aromatic hydrocarbon radicals or an hydroxy ester of said lactone and a primary or secondary alcohol having a boiling point lower than that of the diol, diamine, aminoalcohol, dimercaptan, mercapto alcohol, water or hydrogen sulphide; and a 1,2-epoxide of the general formula <FORM:0887180/IV (a)/2> in which R11 is hydrogen or an alkyl, chloroalkyl, hydroxyalkyl, vinyl or phenyl radical or in which the two R11's taken together complete a closed hydrocarbon ring; reacting said reaction mixture with a molar excess of an organic diisocyanate to form isocyanate-extended oxyalkylene-carboxyalkylene polymers and converting such polymers to a non-hardening gum stock by reaction with a diol, a diamine or an amino alcohol. The gum stock obtained can be cured by reaction with e.g. 3 to 7% by weight of an organic polyisocyanate. Epoxides mentioned are ethylene and propylene oxides, 1-methyl-1,2-propylene oxide, 1,2-butylene oxide, butadiene monoxide, epichlorhydrin, glycidol, cyclohexene oxide and styrene oxide. The oxyalkylene-carboxyalkylene polymers are believed to have the formula <FORM:0887180/IV (a)/3> in which Y is -O-, -S-, NH- or NR1111, (R1111 being a hydrocarbon radical), R111 is an aliphatic, cycloaliphatic, aromatic or heterocyclic radical, the L's are lactone residues of the formula -(CR2)nCHR-, the E's are segments of the formula -CHR11.CHR11-, the x's average from one-half to 6 1/2 , the y's average from 1 to 50 and the L's and E's are in random or ordered distribution. Such polymers can be obtained by reacting the lactone, the epoxide and the difunctional compound at an elevated temperature in the presence of a catalyst, preferably a Lewis acid. The distribution of lactone and epoxide residues in that case depends on the temperature of reaction and ratio of reactant quantities. As an alternative, giving ordered distribution of oxy and carboxy groups, the lactone is reacted in the presence of an esterinterchange catalyst with, e.g. 5 to 20 mols of a monohydric alcohol (aliphatic, cycloaliphatic or aromatic), the ester obtained is reacted with the epoxide in the presence of a base or Lewis acid and the resulting product is reacted with excess of the difunctional compound, preferably in the presence of a basic or neutral esterinterchange catalyst. Preferably the polymer obtained has a molecular weight of 1,800 to 2,800. It may be mixed with a lactone polyester described in Specification 859,642 before the reaction with excess diisocyanate. This latter step can be catalyzed with organic tertiary amines, and substituted phosphines or retarded by acids, aryl halides, sulphonyl halides, inorganic acid halides, sulphur dioxide or acid sulphones. Suitable difunctional compounds for the extension of the resulting isocyanate-terminated polymer are listed. The final curing of the gum stock can be effected by mixing in polyisocyanate on a rubber mill and curing in a mould at 140 DEG to 160 DEG C. When the oxyalkylenecarboxyalkylene polymer has been prepared, it can be reacted in a continuous process with polyfunctional reactant and excess polyisocyanate in a continuous process to give the cured elastomer. Another method is to react the oxyalkylene-carboxyalkylene polymer with 1,2 to 2 mols of diisocyanate to form a prepolymer, and to react the product with less than an equivalent amount of difunctional reactant, the excess of isocyanate-modified oxyalkylene-carboxyalkylene polymer serving to cross-link the resin. It is also possible to react a mixture of the oxyalkylene-carboxyalkylene polymer and the polyfunctional reactant with a less than equivalent amount of polyisocyanate to give the non-hardening gum stock. To the polyurethane resin may be added carbon black, clays, zinc oxide, titanium oxide, dyes, plasticizers such as polyesters, stearic and other fatty acids and their esters, metal salts of fatty acids, dioctylphthalate, tetrabutyl thiodisuccinate and mould-release agents. Specifications 859,639 and 859,644 also are referred to.