GB809809A - Polymeric isocyanates and their manufacture - Google Patents

Abstract

Polymeric organic isocyanates are prepared by contacting an organic polyisocyanate with at east one basic 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 aliphatic and alicyclic carboxylic acids. The invention also comprises isocyanurate polymers of diisocyanates containing at least one aliphatically or cycloaliphatically linked isocyanate group, attached to an aromatic nucleus, isocyanurate polymers of m-xylylene diisocyanate [C6H4(CH2NCO)2], and isocyanurate polymers of chlorphenylene-2,4-diisocyanate. The catalysts are stated to promote the formation of polymers containing the isocyanurate ring. Numerous catalysts are specified. The reaction may be carried out in the absence or presence of a solvent such as an ester, ketone, hydrocarbon, chlorinated hydrocarbon, phenol or ether. The reaction may be stopped by filtering off the catalyst, where insoluble, or by neutralizing it with a strong acid. Amounts of catalyst mentioned are 0.01 to 10 per cent by weight of the organic isocyanate. The reaction temperature is preferably below 200 DEG C. and may be ambient. Many di- and tri-isocyanates are specified for polymerization. The polyisocyanates may be polymerized with aromatic mono-isocyanates, e.g. phenyl-, tolyl-, chlorphenyl- or methoxyphenyl-isocyanates. The products may be reacted with, for example, phenols, acetoacetic esters, malonic esters and diphenylamine; the resulting compounds behave as free isocyanates at elevated temperatures. The isocyanate polymers and their reaction products may be used as adhesives, curing agents, e.g. for isocyanate modified polyesters or polyether raw rubbers or as components thereof, or instead of the monomeric isocyanates in various applications. They may be used as the substantially monomer-free practically fully converted polymer, in solution in the polyisocyanate from which they are derived, in admixture with other polyisocyanates, or in organic solvents such as chloroform, methylene dichloride, esters (e.g. ethyl acetate), ketones (e.g. acetone) or benzene hydrocarbons. Examples describe the preparation of polymers, all containing the isocyanurate ring and having free isocyanate groups from: 2,4-tolylene diisocyanate; a mixture of 2,4- and 2,6-tolylene diisocyanates; (4,5,8) diisocyanatodiphenylmethane; (12) hexamethylene diisocyanate; (15) chlorphenylene - 2,4 - diisocyanate; (19) m - xylylene diisocyanate: (20) 2,4,6 - triiso-cyanatotoluene. Catalysts used are sodium methoxide, fused sodium acetate, lead 2-ethylhexoate, lead naphthenate manganese linoleate, sodium p-octylphenate, potassium carbonate, potassium hydroxide, calcium hydroxide, barium oxide and sodio ethyl acetoacetate. White spirit and/or ethyl acetate or monochlorobenzene may be used as solvent for the reaction. In Examples (11) and (22), polymers from mixtures of 2,4- and 2,6-tolylene diisocyanates are reacted with phenol in acetone or b -ethoxyethyl acetate solution. In Example (21) a mixture of 2,4- and 2,6-tolylene diisocyanates is reacted with phenyl isocyanate.ALSO:Polymeric organic isocyanates are prepared by contacting an organic polyisocyanate with at least one basic 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 aliphatic and alicyclic carboxylic acids. The invention also comprises isocyanurate polymers of diisocyanates containing at least one aliphatically or cycloaliphatically linked isocyanate group, attached to an aromatic nucleus, isocyanurate polymers of m-xylylene diisocyanate [C6H4(CH2NCO)2], and isocyanurate polymers of chlorphenylene-2,4-diisocyanate. The catalysts are stated to promote the formation of polymers containing the isocyanurate ring. Numerous catalysts are specified. The reaction may be carried out in the absence or presence of a solvent such as an ester ketone, hydrocarbon, chlorinated hydrocarbon, phenol, or ether. The reaction may be stopped by filtering off the catalyst, where insoluble, or by neutralizing it with a strong acid. Amounts of catalyst mentioned are 0.01 to 10 per cent by weight of the organic isocyanate. The reaction temperature is preferably below 200 DEG C. and may be ambient. Many di- and tri-isocyanates are specified for polymerization. The products may be reacted with, for example, phenols, acetoacetic esters, malonic esters and diphenylamine; the resulting compounds behave as free isocyanates at elevated temperatures. The isocyanate polymers and their reaction products may be used as adhesives, curing agents or instead of the monomeric isocyanates in various applications. Examples describe the preparation of polymers, all containing the isocyanurate ring and having free isocyanate groups from: 2,4-tolylene diisocyanate; a mixture of 2,4- and 2,6-tolylene diisocyanates; diisocyanatodiphenylmethane; hexamethylene diisocyanate; chlorphenylene - 2,4 - diisocyanate; m-xylylene diisocyanate; 2,4,6 - triisocyanatotoluene. Catalysts used are sodium methoxide, fused sodium acetate, lead 2-ethylhexoate, manganese linoleate, sodium p-octylphenate, potassium carbonate, potassium hydroxide, calcium hydroxide, barium oxide and sodio ethyl acetoacetate. White spirit and/or ethyl acetate may be used as solvent. In Examples (11) and (22) polymers from mixtures of 2,4- and 2,6-tolylene diisocyanates are reacted with phenol in acetone or b -ethoxyethyl acetate solution. In Example (4) diisocyanatodiphenylmethane starting material is prepared by reacting aniline with formaldehyde to give a mixture of 2,41 and 4,41-diaminodiphenylmethane which is then phosgenated.