Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1985-08-22
1987-07-21
Griffin, Ronald W.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
527301, 156336, C08B 3716
Patent
active
046819347
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a plastic crosslinking agent which is chemically stable at room temperature and prepared by converting a compound having isocyanate group(s) into a cyclodextrin clathrate compound and a process for the preparation of the same.
BACKGROUND OF THE INVENTION
Compounds having isocyanate group(s) exhibit excellent properties as a crosslinking agent. However, these compounds have some disadvantages such that they are liable to react with water, bases, acids, ammonia, amines, alcohols, phenols, carboxylic acids and acid anhydrides at room temperature and that it is difficult to interrupt the above reactons once they start. In order to overcome these disadvantages, there have been proposed processes wherein an isocyanate compound is tentatively reacted with an appropriate compound such as an amine, acidic sulfite, tertiary alcohol, oxime, prussic acid, boric acid, phenol, mercaptan or enol lactam to thereby give a product in the form of an isocyanate regenerating material or an ioscyanate adduct, which is heated to regenerate or dissociate the original isocyanate compound when used as a crosslinking agent (cf. Japanese Patent Publication No. 30846/1980 and No. 41841/1983). However, these processes have some disadvantages in that the regeneration step as described above requires a high temperature of 160.degree. to 180.degree. C. and that the regeneration ratio of the isocyanate regenerating material falls upon storage.
SUMMARY OF THE INVENTION
We have found that heating a cyclodextrin clathrate compound of an isocyanate compound to approximately 100.degree. C. results in the regeneration of the original isocyanate compound and that the above-mentioned clathrate compound can be stored at room temperature, thus completing the present invention.
Accordingly, it is an object of the present invention to make it possible to readily apply excellent plastic crosslinking effects of compounds having isocyanate group(s) to various plastic products by providing a plastic crosslinking agent comprising a cyclodextrin clathrate compound of a compound having isocyanate group(s) and a process for the preparation of the cyclodextrin clathrate compound of the compound having isocyanate group(s) which comprises reacting the compound having isocyanate group(s) with cyclodextrin at a temperature of 65.degree. C. or below in water to give the cyclodextrin clathrate compound of the isocyanate compound and recovering the clathrate compound thus formed from the water.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Examples of the compounds having isocyanate group, which will be referred to as IC hereinbelow, are as follows: ##STR1##
The cyclodextrin used in the present invention (hereinafter referred to as CD) may be in any of the .alpha.-, .beta.- or .gamma.-forms although the .beta.- and .gamma.-forms are preferable since they bring about a particularly high yield of the cyclodextrin clathrate compound considering the molecular size of the isocyanate compound.
A CD clathrate compound of an IC may be prepared by dissolving the CD in water (usually by heating to the boiling point of the water), adding dropwise the IC to the aqueous solution thus formed while vigorously stirring at a temperature of 60.degree. C. or below, since a temperature higher than 60.degree. C. would cause foaming which might lower the yield of the CD clathrate compound, allowing the reaction mixture to stand for two to 20 hours and collecting the CD clathrate compound thus precipitated. The obtained CD clathrate compound is dehydrated to give a compound containing 20 to 30% water which may be stored preferably in a dark and cool place. The mixing ratio of the IC to the CD in the above-mentioned process may be usually in the range of 2 to 4:1 depending on the molecular weight of the IC.
A CD clathrate compound of an IC is available in an extremely wide range as a plastic crosslinking agent as such or together with other appropriate additives. The original IC can be regenerated by removing the CD from the CD clathrate compound of th
REFERENCES:
patent: 3459732 (1969-08-01), Hull et al.
patent: 4356115 (1982-10-01), Shibanai et al.
patent: 4482709 (1984-11-01), Iwao et al.
Hawley, The Condensed Chemical Dictionary, Ninth Edition, Van Nostrand Reinhold Company, New York, N.Y., p. 464.
Horikoshi Koki
Kato Takashi
Shibanai Ichiro
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