Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Reexamination Certificate
1998-11-09
2001-09-18
Shaver, Paul F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
C556S458000
Reexamination Certificate
active
06291697
ABSTRACT:
TECHNICAL FIELD
The present invention relates to novel and useful siloxane compounds, and their preparation processes and uses thereof.
RELATED ART
Attempts for improving the coating properties and qualities such as hardness, acid resistance, weather resistance, etc., have been made by introducing alkoxysilyl groups into organic resins. Recently, it has been conducted to study single use of alkoxysilanes such as tetraethoxysilane, tetramethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, dimethyldimethoxysilane and vinyltrimethoxysilane or the oligomers produced from partial hydrolytic condensation of these alkoxysilanes, or combined use of these alkoxysilanes or their oligomers with pertinent resins as coating materials. The present inventors have previously proposed a suspension containing the microfine particles of a compound having the silanol-based reactive functional groups and capable of providing a very useful curable composition either by itself as a blend with the organic substances such as various types of resins and silane couplers (W095/17349), and compositions comprising the siloxane compounds represented by the following formula:
SiO
a
(OH)
b
(OR
1
)
c
(OR
2
)
d
wherein 0.8≦a≦1.6, 0.3≦b≦1.30, 0.2≦c+d≦1.9, b=4−(2a+c+d), R
1
is a methyl or ethyl group, and R
2
is an organic group other than R
1
(Japanese Patent Application No. 7-157897).
The present inventors have also proposed the silicate compounds having a weight-average molecular weight of 600 to 2,200, which, although unable to cure by themselves, have prominently high storage stability (Japanese Patent Application No. 7-272433). These compounds are expected to motivate an improvement of the coating properties such as stain resistance, weather resistance and acid resistance when added in an amount of several to several ten percents to the organic components of various types of coating compositions.
The above-mentioned suspension and siloxane compounds are indeed capable of maintaining a liquid state stable in appearance for a long time, but it was found that when the solution is used for coating after having been preserved for longer than a prescribed period of time, the formed coating tends to deteriorate in its qualities such as hardness and resistance to boiling water. This is considered due to slow advance of the condensation reaction because of high reactivity of the silanol groups in the compound, resulting in a decrease of the silanol-based reactive functional groups. It was therefore considered that usefulness of these suspension and siloxane compounds would be greatly enhanced if their stability in the liquid state could be improved. Regarding the silicate compounds, it was disclosed by the present inventors that the larger their molecular weight, the more remarkable the effect of bettering the coating properties such as stain resistance, weather resistance, acid resistance, etc., is obtained when such compounds are added to the organic component of a coating composition. Development of the silicate compounds with higher molecular weights is therefore required. However, in producing a siloxane compound from hydrolytic condensation of an alkoxysilane, it is necessary for increasing the molecular weight of the produced compound to supply a large amount of water used for the hydrolysis. Supply of a large amount of water would lead to gelation of the compound, making it unable to obtain a stable liquid-state compound.
DESCRIPTION OF THE INVENTION
As a result of the present inventors' earnest studies to solve the above problems, it has been found that it is possible to obtain siloxane compounds which have high molecular weights and radiuses of inertia thereof falling within a specified range, are represented by a specific formula, are capable of minimizing in change of the functional groups with time, and can stay stably in a liquid state. The present invention has been attained based on this finding.
Thus, the present invention is constituted by:
(1) The siloxane compounds represented by the following formula:
SiO
a
(OH)
b
(OR
1
)
c
(OR
2
)
d
wherein 1.0≦a≦1.6, 0≦b<0.3, 0.2≦c≦2.0, 0≦d≦1.4, 2a+b+c+d=4, R
1
is a methyl or ethyl group, and R
2
is an organic group different from R
1
;
(2) The siloxane compounds according to the above item (1), the said compounds having a radius of inertia of not more than 100 Å;
(3) The siloxane compounds according to the above items (1) or (2), the said compounds having a weight-average molecular weight in the range of 2,000 to 40,000;
(4) The siloxane compounds according to the above items (1) to (3), the said compounds containing a solvent;
(5) A liquid composition containing a siloxane compound as defined in any one of the above items (1) to (4);
(6) A liquid composition comprising a blend of a siloxane compound as defined in any one of the above items (1) to (4) and an organic compound compatible therewith;
(7) A liquid composition comprising a blend of a siloxane compound as defined in any one of the above items (1) to (4) and a powder;
(8) A liquid composition comprising a blend of the liquid composition as defined in the above item (6) and a powder;
(9) A cured product of a liquid composition as defined in any one of the above items (5) to (8);
(10) A process for producing a siloxane compound as defined in any one of the above items (1) to (4), which comprises hydrolytically condensing a tetraalkoxysilane by adding 1,0- to 1.6-fold molar quantity of water;
(11) A process for producing a siloxane compound as defined in any one of the above items (1) to (4), which comprises preparing a tetraalkoxysilane oligomer by hydrolytically condensing a tetraalkoxysilane monomer by adding less than 1.6-fold molar quantity of water, and further subjecting the said oligomer to hydrolytic condensation by adding water;
(12) A process for producing a siloxane compound as defined in any one of the above items (1) to (4), which comprises removing the alcohol produced in the hydrolytic condensation reaction of the tetraalkoxysilane out of the reaction system;
(13) A process for producing a siloxane compound as defined in any one of the above items (1) to (4), wherein when removing the alcohol produced in the hydrolytic condensation reaction of the tetraalkoxysilane out of the reaction system, a solvent having a higher boiling point than the alcohol is allowed to exist in the reaction system, and the system is maintained at a temperature lower than the boiling point of the solvent;
(14) The siloxane compound producing process according to any one of the above items (10) to (13), wherein the tetraalkoxysilane is tetramethoxysilane;
(15) The siloxane compound producing process according to any one of the above items (10) to (13), wherein addition of water to the tetraalkoxysilane is conducted at a temperature not exceeding 50° C.
REFERENCES:
patent: 2 155 281 (1973-05-01), None
patent: 0 771 835 A2 (1977-05-01), None
patent: 0 401 388 A1 (1990-12-01), None
patent: 9-12583 (1997-01-01), None
patent: 9-110887 (1997-04-01), None
Endo Hozumi
Kato Hanako
Katsumata Haruo
Oba Kenji
Sawai Takeshi
Mitsubishi Chemical Corporation
Nixon & Vanderhye
Shaver Paul F.
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