Organic compounds -- part of the class 532-570 series – Organic compounds – Four or more ring nitrogens in the bicyclo ring system
Patent
1988-12-16
1990-06-26
Schwartz, Richard A.
Organic compounds -- part of the class 532-570 series
Organic compounds
Four or more ring nitrogens in the bicyclo ring system
C07D25132
Patent
active
049373390
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
TECHNICAL FIELD
This invention relates to a novel process for preparing isocyanurate ring-containing materials which are useful in the production of lacquers and foams.
BACKGROUND ART
Isocyanurate ring-containing materials are usually prepared by trimerizing an organic isocyanate compound in the presence of a catalyst. Catalysts suitable for the trimerization include organic strong bases such as alkali metal salts of carboxylic acids, alkali metal phenolates, alkali metal carbonates, tertiary amines, tertiary phosphines, onium compounds of nitrogen or phosphorus, and as well as heterocyclic compounds containing such elements [see J. H. Saunders and K. C. Frisch, "Polyurethanes: Chemistry and Technology" (1962), p. 94]. Moreover, it is known that the reaction products of Mannich bases or tertiary amines with alkyl esters of phosphoric acid, phosphorous acid or phosphoric acid can also be used as trimerization catalysts.
However, such conventional trimerization catalysts have the disadvantage that they tend to yield yellow-colored reaction products. Another disadvantage thereof is that, where 2,4-tolylene diisocyanate is used as the starting material, it is very difficult to yield its trimer selectively without careful control of reaction conditions such as the amount of catalyst, reaction temperature and reaction time. Consequently, polynuclear by-products having poor solubility tend to be formed.
The object of the present invention is to overcome the above described disadvantages of the prior art processes for preparing the trimers of organic isocyanate compounds by using conventional catalysts.
As a result of extensive investigation of the reactions of isocyanates, the present inventor has found that potassium fluoride catalytically accelerates the trimerization of organic isocyanate compounds. The present invention has been completed on the basis of this finding.
DISCLOSURE OF INVENTION
According to the present invention, there is provided a process for preparing isocyanurate ring-containing materials by trimerization of an organic isocyanate compound, the process being characterized in that potassium fluoride is used as the catalyst, preferably in combination with a polyethylene oxide compound, a quaternary ammonium salt and/or a phosphonium compound.
BEST MODE FOR CARRYING OUT THE INVENTION
The potassium fluoride used in the process of the present invention can take any of various forms including pellets, powder and flakes. However, it is preferable from the viewpoint of catalytic activity and economy to use potassium fluoride in powder form. The potassium fluoride can be supported on a carrier such as celite or active carbon.
The process of the present invention can be applied to organic isocyanate compounds such as aliphatic and aromatic mono-, di- or polyisocyanates. Preferred examples of aliphatic isocyanates include methyl isocyanate, n-butyl isocyanate, n-octyl isocyanate, stearyl isocyanate, hexamethylene diisocyanate and isophorone diisocyanate, and preferred examples of aromatic isocyanate include phenyl isocyanate, 2,4- and 2,6-tolylene diisocyanates, and diphenylmethane diisocyanate. Where diisocyanates (such as 2,4-tolylene diisocyanate) having two isocyanatc groups different in reactivity from each other are used, there can readily be prepared isocyanurate ring-containing polyisocyanates in which only half of the starting isocyanate groups have participated in the reaction.
Moreover, where one or more certain compounds known as phase transfer catalysts are used in combination with potassium fluoride, the rate of trimerization of the organic isocyanate compound can be markedly enhanced as compared with that achievable with potassium fluoride alone.
More specifically, such certain compounds comprise one or more compounds selected from the groups consisting of (i) polyethylene oxide compounds, (ii) quaternary ammonium salts and (iii) phosphonium compounds.
Examples of the compounds falling within the aforesaid categories of (i) to (iii) are as follows.
Useful polyethy
REFERENCES:
patent: 3609149 (1971-09-01), Matsui et al.
patent: 4487928 (1984-12-01), Richter et al.
patent: 4865795 (1989-09-01), Shiomura et al.
Saunders, J. H., and K. C. Frisch, "Polyurethanes: Chemistry and Technology" (1962), p. 24.
Haseyama Ryuzi
Shiomura Tetsunosuke
Sonobe Yoshiho
Yamaguchi Akihiro
Mitsui Toatsu Chemicals Incorporated
Richter J.
Schwartz Richard A.
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