Process for the preparation of polyester polyols, based on 2-methyl-1,4-butanediol, which are liquid at room temperature, and their use for the preparation of plastic materials

A process for making cellular or noncellular isocyanate addition polymer plastic molded articles, comprising reacting:

• (a) an organic polyisocyanate;
• (b) a polyester polyol, which is liquid at room temperature and contains units having the structure --OCH.sub.2 --CH(CH.sub.3)--CH.sub.2 --CH.sub.2 O--, an average functionality of from about 2 to 3, a hydroxyl number of from about 25 to 300, an acid number less than about 2, and a viscosity at 25.degree. C. of about 200 to 10.sup.5 mPas;
• (c) a chain extending agent;
• and,
• (d) an amidine catalyst present in a catalytically effective amount, selected from the group consisting of sodium hypochlorite 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, triethylamine, tributylamine, dimethylbenzylamine, N-methylhexylmorpholine, N-ethylhexylmorpholine, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, pentamethyl-diethylenetriamine, tetramethyldiaminoethyl ether, bis-(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azo-bicyclo[3.3.0]octane, 1,4-dioxabicyclo[2.2.2]octane and mixtures thereof
• whereby the equivalent ratio of NCO groups of the polyisocyanate (a) to the total reactive hydrogen atoms of (b) and (c) is from about 1:0.85 to 1:1.25.