Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-09-30
2001-07-03
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S032000, C528S031000, C549S215000, C502S158000, C558S303000
Reexamination Certificate
active
06255428
ABSTRACT:
This invention relates to a process for preparing an epoxy group-bearing organopolysiloxane or organosilane.
BACKGROUND OF THE INVENTION
An epoxy group-bearing organopolysiloxane or organosilane is prepared by effecting addition reaction between SiH groups on an organohydropolysiloxane or organohydrosilane and alkenyl groups on an alkenyl group-bearing epoxy compound in the presence of a catalyst.
During this addition reaction, polymerization reaction of epoxy groups can take place as a side reaction, resulting in a reaction product having a substantially increased viscosity or being gelled. The thickening and gelation become outstanding particularly when the alkenyl group-bearing epoxy compound is added dropwise to a mixture of the organohydropolysiloxane and the addition reaction catalyst, or when the addition reaction catalyst is added to a mixture of the organohydropolysiloxane and the alkenyl group-bearing epoxy compound to conduct batch reaction.
One known process of preparing an epoxy group-bearing organopolysiloxane while suppressing polymerization of epoxy groups involves mixing a SiH group-bearing silane or siloxane with a tertiary amine and a hydrosilylation catalyst, and reacting the mixture with an olefin epoxide to produce an epoxy silicone (see JP-A 6-32906). While the epoxy silicone is often used in such an application as a coating to be cured with an acid generator, typically an onium salt, this process has a possibility that the tertiary amine be left in the epoxy silicone and restrain the silicone from being cured with the acid generator.
It is also known from JP-A 6-136126 to prepare an epoxy silicone by effecting addition reaction between an organohydrogensiloxane or organohydrogensilane and an ethylenically unsaturated epoxide in the presence of a hydrosilylation catalyst comprising a phosphine ligand and a phosphine-free transition metal complex. Depending on the amount of the phosphine ligand relative to the phosphine-free transition metal complex, there can arise a problem that gelation occurs due to the polymerization of epoxy groups or the addition reaction does not proceed at all.
Therefore, an object of the invention is to provide a novel and improved process for preparing an epoxy group-bearing organopolysiloxane or organosilane through addition reaction between an organohydropolysiloxane or organohydrosilane and an alkenyl group-bearing epoxy compound while avoiding the undesired phenomenon of gelation or thickening.
SUMMARY OF THE INVENTION
The invention is directed to a process for preparing an epoxy group-bearing organopolysiloxane or organosilane by effecting addition reaction between an organohydropolysiloxane or organohydrosilane and an alkenyl group-bearing epoxy compound in the presence of an addition reaction catalyst. The inventor has found that when a cyano group-bearing compound is added to the reaction system, quite unexpectedly, neither gelation nor thickening occurs during the reaction. The viscosity of the epoxy group-bearing organopolysiloxane or organosilane being produced is stabilized.
The invention provides a process for preparing an epoxy group-bearing organopolysiloxane or organosilane by effecting addition reaction between SiH groups on an organohydropolysiloxane or organohydrosilane and alkenyl groups on an alkenyl group-bearing epoxy compound in the presence of an addition reaction catalyst, characterized in that a cyano group-bearing compound is co-present during the reaction.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The process of the invention starts with an organohydropolysiloxane or organohydrosilane, which is not critical insofar as it has at least one SiH group in a molecule. Straight, branched or cyclic ones may be used. Typical organohydropolysiloxanes are given below although the invention is not limited thereto.
H
a
R
3−a
SiO—(HRSiO)
p
—(R
2
SiO)
q
—SiR
3−a
H
a
(H
a
R
3−a
SiO
½
)
w
—(HRSiO)
x
—(R
2
SiO)
y
—(RSiO
{fraction (3/2)}
)
z
Herein, R represents substituted or unsubstituted monovalent hydrocarbon groups of 1 to 10 carbon atoms, for example, alkyl groups such as methyl, ethyl, propyl and butyl, cycloalkyl groups such as cyclohexyl, aryl groups such as phenyl and tolyl, and substituted ones of these groups in which some or all of the hydrogen atoms attached to carbon atoms are replaced by hydroxyl groups, cyano groups or halogen atoms, such as hydroxypropyl, cyanoethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl.
Letter a is an integer of 0 to 3, p and q are integers inclusive of 0, and the sum of p+q is such a number that the organohydropolysiloxane may have a viscosity of about 0.5 to 50,000 centipoise at 25° C., with the proviso that a and p are not equal to 0 at the same time. Letter r is an integer of at least 1, s is an integer inclusive of 0, and the sum of r+s is at least 3, preferably from 3 to 20. Letters w and z are integers of at least 1, x and y are integers inclusive of 0, and the sum of w+x+y+z is such a number that the organohydropolysiloxane may have a viscosity of about 1 to 50,000 centipoise at 25° C., with the proviso that a and x are not equal to 0 at the same time.
Preferably the organohydropolysiloxane has a viscosity of about 10 to 10,000 centipoise at 25° C. A mixture of two or more organohydropolysiloxanes is also useful.
Several illustrative examples of the organohydropolysiloxane are given below. In the following formulae and throughout the specification, Me is methyl.
Me
3
SiO—(HMeSiO)
10
—(Me
2
SiO)
40
—SiMe
3
Me
3
SiO—(HMeSiO)
6
—SiMe
3
Me
3
SiO—(HMeSiO)
10
—(Me
2
SiO)
35
—(Ph
2
SiO)
5
—SiMe
3
HMe
2
SiO—(HMeSiO)
3
—(Me
2
SiO)
10
—SiMe
2
H
(HMe
2
SiO
½
)
5
—(HMeSiO)
6
—(Me
2
SiO)
40
—(MeSiO
{fraction (3/2)}
)
4
Typical organohydrosilanes are represented by the following formula although the invention is not limited thereto.
H
b
SiR′
4−b
Herein, b is an integer of 1 to 4, and R′ represents substituted or unsubstituted monovalent hydrocarbon groups of 1 to 10 carbon atoms, alkoxy groups of 1 to 10 carbon atoms, halogen atoms or similar groups. Exemplary groups represented by R′ are alkyl groups such as methyl, ethyl, propyl and butyl, cycloalkyl groups such as cyclohexyl, aryl groups such as phenyl and tolyl, substituted ones of these groups in which some or all of the hydrogen atoms attached to carbon atoms are replaced by hydroxyl groups, cyano groups or halogen atoms, such as hydroxypropyl, cyanoethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl as well as methoxy, ethoxy, and phenoxy groups and chlorine atoms.
Another starting reactant is an alkenyl group-bearing epoxy compound which is an organic compound having at least one epoxy group and at least one alkenyl group in a molecule. Examples include 4-vinylcyclohexene oxide, 4-isopropenyl-1-methylcyclohexene oxide, allyl glycidyl ether, 1,5-hexadiene monoxide, and glycidyl (meth)acrylate, with the 4-vinylcyclohexene oxide and allyl glycidyl ether being preferred.
For reaction, the organohydropolysiloxane or organohydrosilane and the alkenyl group-bearing epoxy compound are preferably used in such a proportion that the number of alkenyl groups is greater than the number of SiH groups, that is, the molar ratio of alkenyl groups to SiH groups is at least 1.00, more preferably from 1.05 to 1.5.
Platinum catalysts and rhodium catalysts are exemplary of the addition reaction catalyst, with the platinum catalysts being preferred. Examples include chloroplatinic acid, alcohol solutions of chloroplatinic acid, reaction products of chloroplatinic acid with alcohols, reaction products of chloroplatinic acid with olefins, and reaction products of chloroplatinic acid with vinyl group-bearing siloxanes.
The amount of the addition reaction catalyst used is not critical. Preferably the catalyst is used in such an amount as to provide about 1 to 10,000 ppm, and more preferably about 1 to 500 ppm of a platinum group metal (e.g., platinum or rhodium element) based on the alkenyl group-bearing epoxy compound.
According to the invention, a cyano group-be
Aoki Shunji
Ohba Toshio
Birch & Stewart Kolasch & Birch, LLP
Dawson Robert
Peng Kuo-Liang
Shin-Etsu Chemical Co. , Ltd.
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