Patent GB-930458-A (GB)
Title: Process for the purification of isocyanate group-containing compounds
Inventor: KERRIGAN VINCENT
IPC: C08L75/04
Filed: 1960-11-23
Abstract: Isocyanate group-containing reaction products of organic diisocyanates contaminated with said organic diisocyanates are purified by treating a solution of said reaction products in at least one solvent selected from the group consisting of g -butyrolactone, g -valerolactone, sulphur dioxide, dimethyl sulphoxide, ethylene carbonate and sulphite, propylene carbonate and sulphite, nitromethane and nitroethane with an extraction solvent selected from the group consisting of aliphatic and alicyclic hydrocarbons, alkyl aromatic hydrocarbons in each of which the alkyl group or groups together contain at least 8 carbon atoms and dialkyl ether in which the alkyl groups together contain 8 or more carbon atoms.  Preferred solvents for the reaction product are g -butyrolactone, sulphur dioxide and propylene carbonate and preferred extraction solvents are aliphatic petroleum hydrocarbons.  The reaction products may be prepared separate from, or in, the solvent, normally constitute 50 to 500% by weight of the solvent and may be purified batchwise or continuously at a temperature of usually less than 50 DEG C.  After extraction traces of the extraction solvent are preferably removed by reduced pressure distillation at less than 160 DEG C. and, if desired, some or all of the reaction product solvent may be similarly removed.  The process is particularly useful for the reaction products of toluene 2:4- and 2:6-diisocyanates, 1-methyl 2:4- and 1-methyl 2:6-cyclohexane diisocyanate and hexamethylene diisocyanate and in particular for the isocyanurate polymer and reaction products with di- and tri-hydric alcohols of these compounds.  The examples illustrate the purification of polyurethane isocyanates and isocyanurate polymers of toluene diisocyanates using g -butyrolactone or liquid sulphur dioxide and petroleum ethers.ALSO:Isocyanate group-containing reaction products of organic diisocyanates contaminated with said organic diisocyanates are purified by treating a solution of said reaction products in at least one solvent selected from the group consisting of g -butyrolactone, g -valerolactone, sulphur dioxide, dimethyl sulphoxide, ethylene carbonate and sulphite, propylene carbonate and sulphite, nitromethane and nitroethane with an extraction solvent selected from the group consisting of aliphatic and alcyclic hydrocarbons, alkyl aromatic hydrocarbons in each of which the alkyl group or groups together contain at least 8 carbon atoms and dialkyl ethers in which the alkyl groups together contain 8 or more carbon atoms.  Preferred solvents for the reaction product are g -butyrolactone, sulphur dioxide and propylene carbonate and preferred extraction solvents are aliphatic petroleum hydrocarbons.  The reaction products may be prepared separate from, or in, the solvent, normally constitute 50% to 500% by weight of the solvent and may be purified batch-wise or continuously at a temperature of usually less than 50 DEG C.  After extraction traces of the extraction solvent are preferably removed by reduced pressure distillation at less than 160 DEG C. and, if desired, some or all of the reaction product solvent may similarly be removed.  The process is particularly useful for the reaction products of toluene 2 : 4- and-2 : 6-diisocyanates, 1-methyl 2 : 4- and 1-methyl 2 : 6-cyclohexane diisocyanates and hexamethylene diisocyanate and in particular for the isocyanurate polymers and reaction products with di- and tri-hydric alcohols of these compounds.  The examples illustrate the purification of polyurethane isocyanates and isocyanurate polymers of toluene diisocyanates using g -butyrolactone or liquid sulphur dioxide and petroleum ethers.