GB1409496A - Polyurethane polyureas which contain uretdione groups - Google Patents

Abstract

1409496 Polyurethane-polyureas BAYER AG 27 April 1973 [29 April 1972] 20156/73 Heading C3R A uretdione group-containing polyurethane polyurea which contains the structural sequence wherein R 1 and R represent a bivalent aliphatic C 2 -C 36 hydrocarbon radical, a C 4 -C 36 cycloaliphatic hydrocarbon radical and/or a C 8 -C 36 araliphatic hydrocarbon radical and n = 0 or 1 is prepared by reacting (a) a uretdione groupcontaining polyisocyanate with aliphatically bound isocyanate and uretdione groups, optionally mixed with a polyisocyanate which is free from uretdione groups and contains aliphatically bound isocyanate groups; with (b) a primary and/or secondary diamine which contains aliphatically bound amino groups and/or a hydrazine, substituted hydrazine or hydrazine derivative, which contains at least 2 hydrogen atoms attached to nitrogen, which is used as chain lengthening agent. The uretdione-group containing polyisocyanate may be a preploymer of molecular weight 800-30,000, or a monomeric polyisocyanate with a molecular weight below 800. The preferred diamine chainlengtheners have a molecular weight below 400 and contain cycloaliphatically bound amino groups. Preferred hydrazine chain lengtheners are hydrazine hydrate, carbodihydrazide and #-semi-carbazido-propionic acid hydrazide. If a less than equivalent amount of amine is used the polyurethane polyurea may be crosslinked using a basic polyamine such as a monomeric diamine or an α-#-diamino polyester urethane, polyether urethane, polythioether urethane, polycarbonate urethane, polyamide urethane and/or polyurethane urea, or an α-#-diamino polyamide. In Example 1 a uretdione diisocyanate prepolymer, prepared by reacting a polyester of adipic acid and butane-1,4-diol with a mixture of uretdione diisocyanate and 1-isocyanato - 3,3,5 - tri - methyl - 5 isocyanatomethyl-cyclohexane, is reacted with a less than equivalent amount of bis-(4-amino-3-methylcyclohexyl) methane in a toluene/t-butanol solvent mixture. The polyurethane-polyurea thus formed is crosslinked using hexamethylene diamine. In Example 2 the same procedure as Example 1 is used except that the following chain-lentheners are used: 1-amino-5-aminomethyl - 3,3,5 - trimethyl - cyclohexane; hexamethylenediamine, or bis-(4-amino-cyclohexyl)- methane. In Examples 3-8 the same procedure as Example 1 is used except that the following crosslinkers are used: 1 -amino-5-aminomethyl- 3,3,5 - trimethylcyclohexane; bis - (4 - amino- 3-methylcyclohexyl) methane; a polyether based on propylene oxide-propylene diol of M. Wt. 2000 containing primary and secondary amino end groups; a polyurethane-polyurea prepared by reacting a polyester of adipic acid and butane-1-4-diol with an excess of 3,3,5- trimethyl - 5 - isocyanatomethylcyclohexyl isocyanate and either hexamethylenediamine or 3,3,5 - trimethyl - 5 - aminomethyl - cyclohexylamine. In Example 9 an α- #-diisocyanato prepolymer prepared by reacting a polyester of adipic acid and ethylene glycol with a polyisocyanate mixture containing 1-isocyanato-3,3,5- trimethyl 5 - isocyanatomethylcyclohexane and the dimer and trimer thereof in the form of a uretdione diisocyanate and isocyanurate triisocyanate respectively, is reacted with an excess of hexamethylene diamine. The resulting polyurethane-polyurea spontaneously crosslinks.