Catalyst and process for preparing low-viscosity and color-reduced polyisocyanates containing isocyanurate groups

A process for preparing a trimerization catalyst comprising:

• quaternizing a tertiary amine with an alkylating agent thereby forming a quaternary benzylammonium compound;
• and
• converting the quaternary benzylammonium compound into the corresponding carboxylate salt;
• wherein said alkylating agent is selected from the group consisting of Meerwein salts;
• thereby obtaining said trimerization catalyst which is a compound of formula (I):
• and wherein substituents A, B, C, D, and E simultaneously or independently of one another are hydrogen, chloro, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-alkoxycarbonyl, hydroxyl, (R5)3SiO—, (R5)2N—, COOH, (R5)2N—CH2- or phenyl, it being 5 possible for any two adjacent radicals selected from the group A, B, C, D and E to form a conjoint 5- or 6-membered saturated or unsaturated ring which may also include nitrogen, sulfur or oxygen heteroatoms;
• F is hydrogen, methyl or fluoro;
• G is hydrogen, methyl or fluoro;
• R2 and R3 simultaneously or independently of one another are C1-C18-alkyl or R1;
• R4 is hydrogen, methyl, C2-C18-alkyl, C3-C8-cycloalkyl or C2-C12-alkoxy;
• R5 is C1-C18-alkyl;
• Y— is R6COO—;
• R6 is hydrogen or a branched or unbranched aliphatic or araliphatic C1-C12-alkyl radical.

A method for trimerizing diisocyanates, comprising:

• trimerizing diisocyanates in the presence of a trimerization catalyst which is a compound of formula (I):
• and wherein substituents A, B, C, D, and E simultaneously or independently of one another are hydrogen, chloro, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-alkoxycarbonyl, hydroxyl, (R5)3SiO—, (R5)2N—, COOH, (R5)2N—CH2- or phenyl, it being 5 possible for any two adjacent radicals selected from the group A, B, C, D and E to form a conjoint 5- or 6-membered saturated or unsaturated ring which may also include nitrogen, sulfur or oxygen heteroatoms;
• F is hydrogen, methyl or fluoro;
• G is hydrogen, methyl or fluoro;
• R2 and R3 simultaneously or independently of one another are C1-C18-alkyl or R1;
• R4 is hydrogen, methyl, C2-C18-alkyl, C3-C8-cycloalkyl or C2-C2-alkoxy;
• R5 is C1-C18-alkyl;
• Y-is R6COO—;
• R6 is hydrogen or a branched or unbranched aliphatic or araliphatic C1-C2-alkyl radical.

A process for preparing a trimerization catalyst, comprising:

• quaternizing a tertiary amine with an alkylating agent thereby forming a quaternary benzylammonium compound;
• and
• converting the quaternary benzylammonium compound into the corresponding carboxylate salt;
• wherein said converting of said quaternary benzylammonium compound is performed by ion exchange chromatography;
• thereby obtaining said trimerization catalyst which is a compound of formula (I):
• and wherein substituents A, B, C, D, and E simultaneously or independently of one another are hydrogen, chloro, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-alkoxycarbonyl, hydroxyl, (R5)3SiO—, (R5)2N—, COOH, (R5)2N—CH2- or phenyl, it being 5 possible for any two adjacent radicals selected from the group A, B, C, D and E to form a conjoint 5- or 6-membered saturated or unsaturated ring which may also include nitrogen, sulfur or oxygen heteroatoms;
• F is hydrogen, methyl or fluoro;
• G is hydrogen, methyl or fluoro;
• R2 and R3 simultaneously or independently of one another are C1-C18-alkyl or R1;
• R4 is hydrogen, methyl, C2-C18-alkyl, C3-C8-cycloalkyl or C2-C12-alkoxy;
• R5 is C1-C18-alkyl;
• Y-is R6COO—;
• R6 is hydrogen or a branched or unbranched aliphatic or araliphatic C1-C12-alkyl radical.