Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Patent
1991-06-20
1993-05-11
Prescott, Arthur C.
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
525123, 528 45, C07F 710, C08G 7702
Patent
active
052102467
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an amino group-containing silicate composition suitable for dehydrating a very small amount of moisture contained in various chemical reagents. Further, the present invention relates to a dehydrating agent employing such a composition and a resin produced by using a raw material dehydrated by means of such a composition.
BACKGROUND TECHNIQUE
Many chemical reagents and chemical raw materials have their moisture contents stipulated in the product standards. It is evident from this fact that it is very important to control or dehydrate the moisture in chemical reagents and chemical raw materials.
As a dehydration method, it has been common to separate the moisture and the product by distillation or fractional distillation. However, in many cases, it is difficult to completely remove the moisture by distillation. Especially in the case of a substance azeotropically distilled with water or a substance having a strong affinity with water, it is difficult to adequately remove the moisture.
Further, there is a method available in which a solid powder such as molecular sieves or calcium chloride is added to let it adsorb water for dehydration. In this case, it is necessary to remove the solid powder having water adsorbed thereon. As a means for such removal, it is common to employ filtration, but in many cases, it is difficult to remove the solid having water adsorbed thereon.
For example, the moisture in a polyol of a usual grade used as a raw material for the production of urethane, is usually from 1000 to a few hundreds ppm. However, in a case of a grade where the moisture is particularly unwanted, the moisture is required to be not higher than 150 ppm. To remove the moisture in a polyol to a level of from a few hundreds ppm to not higher than 150 ppm, molecular sieves or other solid dehydrating agent, a tetraalkylsilicate or an oligomer obtained by the hydrolysis-dehydration-polycondensation thereof, is used at present. However, in the case of a solid dehydrating agent including molecular sieves, the filtration process is not easy, and in the case of the tetraalkylsilicate or the oligomer obtained by the hydrolysis-dehydration-polycondensation thereof, it takes a long time for dehydration (a few days at room temperature, or about one day at 60.degree. C.).
The present inventors have conducted extensive studies with an aim to develop a useful substance by the reaction of an amino group-containing compound with a silicate and have found that a novel composition obtained by the reaction of a certain specific silicate compound with an amino compound having hydroxyl groups, is an amino compound having a relatively low viscosity and a high boiling point, and such a composition readily reacts with water. The present invention has been accomplished on the basis of this discovery.
DISCLOSURE OF THE INVENTION
The gist of the present invention resides in an amino group-containing silicate composition obtained by reacting a tetraalkoxysilane or a silicate oligomer obtained by hydrolyzing, dehydrating and polycondensing it at a degree of hydrolysis within a range of not higher than 65%, with an amino alcohol having one or two hydroxyl groups, and a dehydrating agent using such a composition.
Now, the present invention will be described in detail. The silicate compound used in the present invention is a tetraalkoxysilane of the following formula or its oligomer: ##STR1## (wherein R.sup.1 to R.sup.4 which may be the same or different, are a lower alkyl group such as methyl, ethyl, propyl or butyl.)
The silicate oligomer is obtained by hydrolyzing, dehydrating and polycondensing the above tetraalkoxysilane monomer. The production of the oligomer is conducted by adding acidic, neutral or alkaline water in a necessary amount to the tetraalkoxysilane monomer and removing the alcohol resulting from the reaction (which forms 2 molar times the amount of the added water).
The reaction is represented as follows: tetraalkoxysilane. However, in reality, a plurality of molecules are
REFERENCES:
patent: 3079656 (1983-03-01), Emblem et al.
patent: 4722969 (1988-02-01), Huynh-Tran et al.
Chemical Abstracts, vol. 76, No. 16, Apr. 17, 1972, p. 38, Abstract No. 86647v & SU-A-292 489.
Katano Hiroaki
Ohtani Masaaki
Tanaka Tetsuya
Dow Mitsubishi Kasei Limited
Mitsubishi Kasei Corporation
Prescott Arthur C.
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