Method for obtaining slightly colored branched polyisocyanate(s), and the resulting composition

摘要

The invention concerns a method for cyclotrimerization of isocyanate functions by action of a catalyst based on quaternary ammonium or phosphonium. The invention is characterised in that said isocyanate functions are branched and said onium ions are selected among those whereof the total amount of carbons is not more than 30 and not less than 12; and whereof the counterion is selected among the anions corresponding to weak acids whereof the pKA is not less than 8, preferably not less than 10, more preferably not less than 12, whereof the substituents are aliphatic compounds and do not have an insaturation in beta; and said onium ions comprise at least 2 radicals of more than 6, advantageously more than 10, preferably more than 12 carbon atoms.