Process for polymerization of isocyanates

Organic isocyanates are polymerized to give products containing isocyanurate rings by treating said isocyanates with a catalyst selected from alkali and alkaline earth metal oxides, hydroxides, carbonates, alcoholates and phenates, alkali metal salts of enolizable compounds and metallic salts of weak carboxylic acids, in the presence of a mono-N-substituted carbamic acid. The latter is preferably formed in situ by the addition of an alcohol or phenol to the isocyanate to be polymerized and may be derived from aliphatic, alicyclic or araliphatic monohydric alcohols, polyhydric alcohols and mono- or polyhydric phenols. A solvent may be used. The proportion of catalyst may be within the range of 0,01 to 10% by weight of the isocyanate, and of the carbamic ester within the range 0,05 to 5% by weight of the isocyanate. The temperature may be from 15 DEG to 250 DEG C., preferably 15 DEG to 75 DEG C. Examples describe the preparation of polymers containing free isocyanate groups from tolylene-2,4-diisocyanate, a mixture of tolylene2,4- and 2,6-diisocyanates, and from hexamethylene diisocyanate. Many other isocyanates are specified. The products may be used in the preparation of polyurethane products. Specifications 809,809 and 842,154 are referred to.ALSO:Organic isocyanates are polymerized to give products containing isocyanurate rings by treating said isocyanates with a catalyst selected from alkali and alkaline earth metal oxides, hydroxides, carbonates, alcoholates and phenates, alkali metal salts of enolisable compounds and metallic salts of weak carboxylic acids, in the presence of a mono-N-substituted carbamic acid. The latter is preferably formed in situ by the addition of an alcohol or phenol to the isocyanate to be polymerized and may be derived from aliphatic, alicyclic or araliphatic monohydric alcohols, polyhydric alcohols and mono- or poly-hydric phenols. A solvent may be used. The proportion of catalyst may be within the range of 0.01 to 10% by weight of the isocyanate, and of the carbamic ester within the range 0.05 to 5% by weight of the isocyanate. The temperature may be from 15 to 250 DEG C., preferably 15 to 75 DEG C. Examples describe the preparation of polymers containing free isocyanate groups from tolylene-2,4-diisocyanate, a mixture of tolylene-2,4- and 2,6-diisocyanates, and from hexamethylene diisocyanate. Many other isocyanates are specified. The products may be used in the preparation of polyurethane products. Specifications 809,809 a