Patent GB-1008345-A (GB)
Title: A process for polymerising isocyanates
IPC: C08G18/79
Filed: 1963-06-24
Abstract: Isocyanates are polymerized in the presence of a catalyst comprising a salt the anion of which has the formula <FORM:1008345/C3/1> wherein X represents another N atom or the group C-R where R is a hydrogen atom or an alkyl, aralkyl or aryl group, and the two free valencies are connected on both sides to organic residues which may be closed to form a heterocyclic ring containing at least two N atoms. The starting materials may be an alkyl, aromatic or cycloaliphatic mono- or poly-iso cyanates or polyurethanes obtained by reacting excess of poly-isocyanate with a compound containing active hydrogen, e.g. hydroxyl polyesters, polyhydric-polyalkylene ethers, polyhydric - polyalkylene thio - ethers, polyesteramides, polyacetals and compounds containing active methylene groups humerous compounds containing active hydrogen are specified.  The starting material may also be a copolymer of an unsaturated isocyanate and another olefinically unsaturated compound.  Also included as starting materials are those compounds which split to give isocyanate groups on heating, e.g. ureas, biurets and allophanates.  Specified catalysts are hydragoic acid, azides, and salts of tetrazoles, triazoles, imidazoles, cyanamides and amidines.  Polymerization can be effected in the range -50 DEG  to + 200 DEG  C., optionally in the presence of a solvent and normally in the presence of 0.001-5% by weight of catalyst. In Example 3a polymer containing free-NCO groups is obtained from 2,4-tolylene diisocyanate in the presence of sodium-5-phenyl tetrazole.  In Example 4 lithium azide is used as a catalyst for 2,4-toluene diisocyanate to give a polymer containing neither -NCO or carbodiimide groups.  Example 5 describes the treatment of a dehydrated polyester of adipic acid and ethylene glycol and 4,41-diphenylmethane diisocyanate with lithium azide to give a cross-linked polymer.ALSO:Isocyanates are polymerized in the presence of a catalyst comprising a salt the anion of which has the formula <FORM:1008345/C2/1> wherein X represents another N atom or a C-R radical in which R represents a hydrogen atom or an alkyl, aralkyl or aryl radical, and the two free valencies are connected on both sides to organic residues which may be closed to form a heterocyclic ring containing at least two nitrogen atoms.  Specified catalysts include hydragoic acid, azides, salts of tetrazoles, imidazoles, triazoles, cyanamides and amidines. The cation of the salt may be derived from alkali metals, alkaline earth metals, tertiary amines or phosphines.  A number of aromatic and cycloaliphatic mono- and poly-isocyanates which can be used as starting materials are specified, including polyurethan type products obtained by reacting excess of a polyisocyanate with a compound containing active hydrogen (see Division C3).  The reaction may be effected at temperatures of -50 to +200 DEG  C., optionally in the presence of a solvent and normally in the presence of 0.001-5% by weight of catalyst. Example I relates to the polymerization of phenol isocyanate to give a mixture of diphenyl uretdione and triphenyl isocyanurate and Example 2 describes the reaction of 2,4-and 2,6-tolyldiisocyanate to give 1,3-bis-(41-methyl - 31 - isocyanato - phenyl) - uretdione.