Abstract: Isocyanates are polymerized in a simple manner by polymerizing aliphatic and/or aromatic isocyanates in the presence of metallocenes at temperatures from 20.degree. to 220.degree. C., optionally subject to increased or reduced pressure and optionally in the presence of an inert organic solvent, the metallocene being used in an amount of 5 to 50,000 ppm relative to the amount of isocyanates used.

Abstract: Compounds containing hydroxyl groups, which are suitable for the polyisocyanate addition polymerization process, are prepared from polyurethane-polyurea and/or polyurea waste materials. These compounds are produced by reacting a finely divided polyurethane-polyurea and/or polyurea waste material with a low molecular weight diol and/or polyol (and optionally a higher molecular weight polyol) and a low molecular weight urea and/or carbamic acid ester. This reaction may be carried in either one stage or two stages. In the two stage process, the waste material and diol/polyol are reacted in a first stage at a temperature of from about 100 to about 260.degree. C. In the second stage, the amine-containing alcoholysis product obtained in the first stage is reacted with a low molecular weight urea and/or carbamic acid ester.

Abstract: Polyols are conditioned and stabilized by mixing them at 0 to 150.degree. C. with from about 0.0001 to about 1% by weight, based on the quantity of polyol, of a silylated acid corresponding to the formula:X--[Si(CH.sub.3).sub.3 ].sub.nin whichX represents a neutral acid residue obtained by removal of the acidic hydrogen atoms from an n-basic acid having a maximum pKa value of 3, provided that the n-basic acid is not a hydrohalic acid andn represents an integer of from 1 to 3.The resultant polyol is characterized by good color and activity properties. The stabilized polyols are particularly useful in the production of polyurethanes, particularly polyurethane foams.