| abstract |
The hydrolysis resistance of a urethane elastomer prepared by reacting a hydroxy compound with a prepolymer in a weight ratio of between 5/95 and 95/5 is improved; the hydroxy compound consists of at least one saturated polyester resin and/or at least one chain-extending agent, if necessary in the presence of the usual additives, each resin and each chain-extending agent having at least two OH end groups; the prepolymer is prepared by reacting at least one saturated polyester resin having at least two OH end groups and at least one organic isocyanate of functionality >/=2, in molar excess. To this end, to prepare at least one polyester resin, a fraction of the polyacid(s) used is replaced by at least one polymerized fatty acid, consisting substantially of a dimer and/or a trimer, the initial total content of polymerized fatty acid(s) being between 1 and 35% by weight, referred to the finished product. The value of the load at break of the elastomer is retained to an extent of at least 50% or has a value at least equal to 5 MPa after hydrolysis. |