content_image/924930.jpg content_image/924931.jpg content_image/924932.jpg
# CATALYST FOR ISOCYANATE CONDENSATION, COMPOSITION CONTAINING SAME, METHOD FOR USE, AND RESULTING COMPOSITIONS 

The invention relates to a novel process for the catalytic ( cyclo )condensation, in particular ( cyclo )trimerization, of isocyanates. 

The trimerization, in particular cyclotrimerization, reac- tion of isocyanates is a known reaction generally catalyzed by: 

basic catalysts: quaternary ammoniums or their hydroxy› alkyl derivatives, alkoxides, phenoxides, Mannich bases, tertiary amines, imide salts, and the like, 

organometallic catalysts: alkyl titanates, lead carboxylates, and the like. 

However, the kinetics of this reaction depend on the structure of the isocyanate and it may be opportune to choose the catalyst according to the nature of the isocyanate. 

Generally, quaternary ammonium carboxylates with the hydroxyalkyl functional group are the catalysts of choice for aliphatic diisocyanates. They give good results at low tern- perature (70 to 80° C.) and in low amount ( of the order of 0.07% by weight with respect to the diisocyanate). 

European patent EP 57 653 (Rhone-Poulenc) discloses hexamethyidisilazane (HMDZ) as trimerization catalyst for aliphatic diisocyanates. However, the amounts of catalyst used and the reaction temperatures are markedly greater than those employed for quaternary ammonium carboxylates, for example of the order of 1.25% by weight of catalyst with respect to HDI and 120° C. 

The studies of the inventors which have led to the present invention have made it possible to discover that the polycondensation, in particular trimerization, reaction of isocyanate monomers could be carried out with salts with silazane or silanolate structures (nontoxic compounds) employed in a low amount at a not very high temperature with an excellent productive output, this being the case without resulting in significant coloring of the reaction medium. 

Surprisingly, the kinetics of the trimerization reaction and the reactivity of the isocyanate monomers are substantially improved when a silazane salt is used in comparison with the corresponding protonated silazane derivative. 

In addition, it has been surprisingly discovered that sila- zane salts or silanolates made it possible to catalyze the polycondensation, in particular the ( cyclo )trimerization, of isocyanates in which the isocyanate functional group is hindered and therefore not very accessible, in particular the isocyanates in which the isocyanate functional group is carried by a secondary, in particular cycloaliphatic, tertiary or neopentyl carbon atom. What is more, the associated cations can be varied in order to balance, in an unusual way, the various oligocondensate entities resulting from the ( cyclo )condensation. 

Thus, according to the invention, saline compounds are used as catalysts for the ( cyclo )condensation of an isocyan- ate functional group, advantageously an aliphatic, including cycloaliphatic, functional group, in which ( cyclo) 65 condensation said saline compound is selected from those which correspond to the formula: 

<img src='content_image/924930.jpg'>

where (Mn+)i;n symbolizes the cocation(s) necessary for the electrical neutrality of said saline compound bal› ancing the anion of formula (I): 

<img src='content_image/924931.jpg'>

where y- is selected from: 

a negatively charged oxygen; 

and a carbonaceous radical compnsmg a negative charge carried by an atom from Group VB or by an oxygen, advantageously by a nitrogen, and for which the bond with the silicon of the above formula (I) is carried by an atom from Group VB, advantageously by a nitrogen; 

where R$_{1}$ , R$_{2 }$ and R$_{3}$ , which are identical or different, represent a monovalent hydrocarbonaceous group advantageously having from 1 to 30 carbon atoms which is optionally substituted by one or more halogen atoms or CN or ester groups and/or is optionally interrupted by one or more atoms selected from 0, N and Si, advantageously of aliphatic nature, including of saturated or unsaturated cycloaliphatic and of aralkyl nature, or of aromatic nature, such as of aryl or alky› lary 1 nature; 

and from those carrying a trialkylsilyl group and resulting from the reaction of said compounds of formula (I) and of an isocyanate functional group, advantageously an aliphatic isocyanate functional group. 

This is because the anionic compounds of formula (I) are capable of forming compounds with the isocyanates, in particular resulting from the addition to the isocyanate functional group. The additions of the anion take place on the carbon of the isocyanate functional group. 

Advantageously, Y represents a radical of formula (II): 

<img src='content_image/924932.jpg'>

in which: 

Z represents a semimetal from Group VB; 

R$_{10 }$ is selected from radicals comprising from 1 to 30 carbon atoms, including silyl and in particular tri› alkylsilyl; and 

R$_{11 }$ is selected from a negative (anionic) charge and a carbonaceous group (advantageously of at most 30 carbon atoms) attached to Z via a carbon simulta› neously of sp $^{2 }$hybridization and carrying a nitrogen, the nitrogen of which carries a negative (anionic) charge. 

According to one embodiment of the invention, it is possible, but without this exhibiting a specific advantage, for the anionic compound of formula 1 to exhibit more than one 

(I) 

(II) 

