JP2003026810A - Organoxy-terminated organopolysiloxane and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organoxy-terminated organopolysiloxane obtained in an industrially advantageous process. SOLUTION: The method for producing the organoxy-terminated organopolysiloxane comprises reaction between (A) an alkenyl-terminated diorganopolysiloxane and (B) a mercapto group-containing organoxysilane of general formula (1): (R<1> O)a R<2> 3-a Si-R<3> -SH (where, R<1> is a 1-8C monovalent hydrocarbon group or alkoxy-substituted monovalent hydrocarbon group; R<2> is a 1-13C monovalent hydrocarbon group; R3 is a 1-6C bivalent hydrocarbon group; and (a) is an integer of 1-3) in the presence of a radical generator.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an organooxy-terminated organopolysiloxane useful as a base polymer of a one-component dealcohol type RTV (room temperature curable organopolysiloxane) composition, and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION One component dealcohol type RTV compositions are well known compositions. These compositions are basically base polymers consisting of silanol terminated diorganopolysiloxane polymers,
It is composed of a cross-linking agent consisting of an alkoxy-functional silane and a siloxane. Such a one-component dealcohol-type RTV composition has advantages that it is not corrosive and has little odor. A representative example of this type is Japanese Examined Japanese Patent Publication Sho 39
No. 27643, which discloses a composition comprising a hydroxyl-endblocked organopolysiloxane, an alkoxysilane and an organotitanium compound. However, in these compositions, it is very difficult to remove the alcohol generated by the reaction between the silanol group at the polymer end and the alkoxy-functional cross-linking agent during the preparation of the composition, and in the composition, There is a problem that the storage stability is deteriorated by the remaining alcohol.

In order to solve this problem, it is effective to use a base polymer in which the terminal silanol group of the silanol-terminated diorganopolysiloxane polymer and the alkoxy-functional crosslinking agent are pre-reacted. US Patent 317
5993 proposes a composition comprising a terminal alkoxy group-containing base polymer having a silalkylene skeleton and US Pat. No. 3,161,614 proposes a composition comprising a terminal alkoxy group-containing base polymer having a siloxane skeleton. Further, JP-A-55-43119 discloses a composition comprising an alkoxysilyl endblocked organopolysiloxane, an alkoxysilane and an alkoxytitanium. Japanese Patent Publication No. 3-8657 proposes to pre-react the terminal silanol groups of the silanol-terminated diorganopolysiloxane polymer with an alkoxy-functional crosslinking agent having hydrogen atoms bonded to silicon. Further, JP-B-7-39547 discloses a composition comprising an alkoxysilyl end-capped organopolysiloxane containing a silethylene group, an alkoxysilane and an alkoxytitanium.

However, in order to industrially prepare these siloxanes whose terminals are alkoxy-modified, it is necessary to complete the reaction at a relatively low temperature in a short time from the viewpoint of cost, and from the viewpoint of production stability. It is important to be less susceptible to environmental factors. The above-described reaction of the alkoxysilane with respect to the silanol terminal requires a long-time process at a relatively high temperature without a catalyst, and when a catalyst is used, the removal of the catalyst is essential and there are many process inconveniences. Vinyl terminated,
When hydrogenated alkoxysilane is used at the silanol end, a platinum-based catalyst is required, and platinum-based catalysts are contaminated by catalyst poisons, so care must be taken in process control. Also,
In any case, since the alkoxysilane to be handled has high volatility, it is necessary to sufficiently control the environmental pollution during production and the safety of workers.

The present invention has been made in order to improve the above circumstances, and is a platinum-based compound which has sufficient curability as a base polymer for a one-component dealcohol-type RTV composition and is easily affected by environmental factors. Without using a catalyst
Further, an organooxy-terminated organopolysiloxane that can be used in the production of an RTV silicone rubber composition that is less toxic to the environment during production due to the low volatility of the terminal modifier and that is easy to ensure the safety of workers, and a method for producing the same. The purpose is to do.

[0006]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above object, the present inventor has found that (A) a diorganopolysiloxane having an alkenyl group at the end and (B) formula ^{(1) (R 1 O)} a R 2 3-a Si-R 3 -SH (1) ( wherein, R ¹ represents a substituted monovalent hydrocarbon monovalent hydrocarbon group or an alkoxy group having 1 to 8 carbon atoms A hydrogen group, R ² is a monovalent hydrocarbon group having 1 to 13 carbon atoms, R ³ is a divalent hydrocarbon group having 1 to 6 carbon atoms, and a is an integer of 1 to 3). By reacting a mercapto group-containing organooxysilane in the presence of a radical generator, an organooxy-terminated organopolysiloxane can be obtained without using a platinum-based catalyst, and the volatility of the terminal modifier is low. As a result, there is little environmental pollution during manufacturing, and it is easy to ensure safety. They found that it was easy and completed the present invention.

Therefore, according to the present invention, (A) a diorganopolysiloxane having an alkenyl group at the terminal and (B) the following general formula (1) (R ¹ O) _a R ² _3-a Si-R ³ -SH ( 1) (In the formula, R ¹ is a monovalent hydrocarbon group having 1 to 8 carbon atoms or an alkoxy group-substituted monovalent hydrocarbon group, R ² is a monovalent hydrocarbon group having 1 to 13 carbon atoms, and R ³ is a carbon number. Which is a divalent hydrocarbon group of 1 to 6, and a is an integer of 1 to 3), and an organooxysilane containing a mercapto group represented by the formula (1) in the presence of a radical generator. Provided is a method for producing an oxy-terminated organopolysiloxane, and an organooxy-terminated organopolysiloxane obtained thereby.

The present invention will be described in more detail below. Component (A) The component (A) of the present invention is a diorganopolysiloxane having an alkenyl group at the end of the molecular chain and forms the basic skeleton of the organooxy-terminated organopolysiloxane. Preferably, the following general formula (2) R ⁴ ₃ SiO (R ⁵ ₂ SiO) _n SiR ⁴ ₃ (2) (In the formula, R ⁴ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms, It contains at least one alkenyl group.
R ⁵ is a monovalent hydrocarbon group having 1 to 13 carbon atoms. Specifically, those containing no aliphatic unsaturated bond are preferable, and examples thereof include an alkyl group, an aryl group, an aralkyl group, a halogen-substituted hydrocarbon group, and a cyanoalkyl group. Also, n
Is an integer of 10 or more. ) Is a diorganopolysiloxane.

Specific examples of R ⁴ include alkyl groups such as methyl group, ethyl group, propyl group, butyl group and hexyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group, aryl groups such as phenyl group and chloromethyl. Group, trifluoromethyl group, chloropropyl group, 3,
Examples thereof include halogen-substituted hydrocarbon groups such as 3,3-trifluoropropyl group. It also contains at least one, and preferably two (one at each end) alkenyl groups such as vinyl and allyl. R ⁴ is preferably a methyl group or a vinyl group.

Specific examples of R ⁵ include methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group,
Decyl group, alkyl group such as octadecyl group, cyclopentyl group, cycloalkyl group such as cyclohexyl group,
Aryl groups such as phenyl group, tolyl group, naphthyl group,
Examples thereof include aralkyl groups such as benzyl group, phenylethyl group and phenylpropyl group, and halogen-substituted hydrocarbon groups include chloromethyl group, trifluoromethyl group,
Examples of the chloropropyl group, 3,3,3-trifluoropropyl group, chlorophenyl group, dibromophenyl group, tetrachlorophenyl group, difluorophenyl group and the like, the cyanoalkyl group, β-cyanoethyl group,
Examples thereof include γ-cyanopropyl group and β-cyanopropyl group. A methyl group is preferred.

N is an integer of 10 or more, preferably 2
Viscosity at 5 ° C is 100 to 1,000,000 mPa
S, particularly preferably 500 to 500,000 mPa
It is a number that becomes s.

[0012] (B) component (B) of the component present invention, the following general formula ^{(1) (R 1 O)} a R 2 3-a Si-R 3 -SH (1) ( wherein, R ¹ is carbon C 1-8 monovalent hydrocarbon group or alkoxy group-substituted monovalent hydrocarbon group, R ² is a C 1-13 monovalent hydrocarbon group, and R ³ is a C 1-6 divalent hydrocarbon group. A is an integer of 1 to 3), which is a mercapto group-containing organooxysilane. The component (B) acts as a terminal modifier for the desired organooxy-terminated organopolysiloxane.

R ¹ is a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an alkyl group such as an octyl group, or an alkoxy group such as a methoxyethyl group, an ethoxyethyl group, a methoxypropyl group or a methoxybutyl group. Examples thereof include an alkyl group and the like, of which a methyl group, an ethyl group, a propyl group and a methoxyethyl group are preferable, and a methyl group and an ethyl group are more preferable.

R ² is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a decyl group or an octadecyl group, a cycloalkyl group such as a cyclopentyl group or a cyclohexyl group, a phenyl group, Examples thereof include an aryl group such as a tolyl group and a naphthyl group, an aralkyl group such as a benzyl group, a phenylethyl group, and a phenylpropyl group. A methyl group, an ethyl group, a propyl group, and a phenyl group are preferable, and a methyl group is particularly preferable. Is.

R ³ is a methylene group, an ethylene group,
Propylene group, butylene group, 2-methylpropylene group,
Examples thereof include alkylene groups such as a pentylene group and a hexylene group, preferably a methylene group, an ethylene group and a propylene group, and particularly preferably a propylene group. Further, a is an integer of 1 to 3, preferably 2 or 3.

As the component (B), for example, mercaptopropyl monoalkyldialkoxysilane or mercaptopropyltrialkoxysilane can be used.
In this case, the usage ratio of the component (A) and the component (B) is
For one alkenyl group of the component (A), S of the component (B)
It is preferable that the amount of H groups is 0.5 to 2, especially about 1.

Component (C) The radical generator, which is the component (C) of the present invention, causes an addition reaction of an alkenyl group having at least one in one molecule of the component (A) and a mercapto group having the component (B). Used as an ingredient for. As the component (C), benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-bis (2,2)
5-t-butylperoxy) hexane, di-t-butylperoxide, organic peroxides such as t-butylperbenzoate, 2,2′-azobisisobutyronitrile,
Examples thereof include those which generate radicals by thermal decomposition of organic azo compounds such as 2,2′-azobis (2-methylbutyronitrile) and those which generate radicals upon irradiation with light. Of these, organic peroxide-based radical generators are highly active, which poses a danger to workers. Therefore, it is preferable to use organic azo-based radical generators. More preferably, 2,2′-azobis (2-methylbutyronitrile) having the longest half-life of radicals is used among the above.

The amount of the above radical generator used is an effective amount (catalyst amount) for reacting the alkenyl group of the component (A) with the SH group of the component (B). 0.001 to 100 parts by weight of component B) in total
It is preferably 0.5 parts by weight, particularly 0.01 to 0.1 parts by weight.

The reaction can be carried out with or without an organic solvent. The reaction temperature is room temperature to 150 ° C., particularly 70 to
It is preferable to carry out at 130 ° C. Further, it is preferable to remove water in the reaction system as much as possible so that the alkoxy group of the component (B) is not hydrolyzed.

[0020]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to the following examples. In addition, the viscosity in the following examples shows a measured value at 25 ° C.

[Example 1] A four-necked flask having an internal volume of 2 liters equipped with a thermometer, a stirrer, a condenser, a nitrogen gas inflow pipe and a gas outflow pipe, and the viscosity of which both molecular chain ends were blocked with vinyl groups. Was charged with 1,300 g of dimethylpolysiloxane of 5,400 mPa · s and 500 g of toluene.
Azeotropic dehydration was carried out at ˜130 ° C. for 1 hour. After cooling to 100 ° C, γ-mercaptopropyltrimethoxysilane was added to 19
g, 0.5 g of 2,2′-azobisisobutyronitrile (AIBN manufactured by Otsuka Chemical Co., Ltd.), and 10 parts of toluene.
g mixture was added dropwise. After completion of the dropping, aging was carried out at 100 ° C. for 2 hours, and after completion of the aging, toluene was distilled off under reduced pressure to obtain 1,180 g of a colorless transparent liquid having a viscosity of 8,000 mPa · s and a nonvolatile content of 99.9%. This colorless transparent liquid 10
When 1 g of tetrabutyl titanate was mixed with 0 g, the viscosity did not increase immediately and it was cured after 1 day. From this, it can be confirmed that γ-mercaptopropyltrimethoxysilane was added to the vinyl group at the polymer terminal. The reaction formula of Example 1 is as follows.

[0022]

[Chemical 1] (N is a number (degree of polymerization) that satisfies the above viscosity.
the same. )

[Example 2] Viscosity in which both ends of a molecular chain were blocked with vinyl groups in a four-necked flask having an internal volume of 5 liters equipped with a thermometer, a stirrer, a cooler, a nitrogen gas inflow pipe and a gas outflow pipe. 2,000 g and 1,000 g of toluene were charged and azeotropic dehydration was performed at 120 to 130 ° C. for 1 hour. 10
After cooling to 0 ° C., 12 g of γ-mercaptopropyltrimethoxysilane and 2,2′-azobis (2-methylbutyronitrile) (V-59 manufactured by Wako Pure Chemical Industries, Ltd.) were used.
A mixture of 0 g and 10 g of toluene was added dropwise. After completion of the dropping, aging is performed at 100 ° C. for 2 hours, and after completion of the aging, toluene is distilled off under reduced pressure to obtain a viscosity of 140,000 mPas.
・ S, colorless transparent liquid with non-volatile content of 99.3% is 1,890
g was obtained. When 100 g of this colorless transparent liquid was mixed with 1 g of tetrabutyl titanate, the viscosity did not immediately increase,
It hardened after 1 day. From this, it can be confirmed that γ-mercaptopropyltrimethoxysilane was added to the vinyl group at the polymer terminal. The reaction formula of Example 2 is the same as the reaction formula of Example 1 described above.

[Example 3] Viscosity in which both ends of a molecular chain were blocked with vinyl groups in a four-necked flask having an internal volume of 2 liters equipped with a thermometer, a stirrer, a cooler, a nitrogen gas inflow pipe and a gas outflow pipe. Was charged with 1,300 g of dimethylpolysiloxane of 5,400 mPa · s and 500 g of toluene.
Azeotropic dehydration was carried out at ˜130 ° C. for 1 hour. After cooling to 100 ° C., γ-mercaptopropyltriethoxysilane was added to 23
g, 2,2'-azobis (2-methylbutyronitrile)
A mixture of 1.0 g of (Wako Pure Chemical Industries, Ltd. V-59) and 10 g of toluene was added dropwise. After completion of dropping, 1
Aging was performed at 00 ° C. for 2 hours, and after completion of the aging, toluene was distilled off under reduced pressure to obtain 1,210 g of a colorless transparent liquid having a viscosity of 7,450 mPa · s and a nonvolatile content of 99.7%. 1 g of tetrabutyl titanate to 100 g of this colorless transparent liquid
When was mixed, the viscosity did not increase immediately and it was cured after 1 day. From this, it can be confirmed that γ-mercaptopropyltriethoxysilane was added to the vinyl group at the polymer terminal. The reaction formula of Example 3 is as follows.

[0025]

[Chemical 2]

[Example 4] A four-necked flask having an internal volume of 2 liters equipped with a thermometer, a stirrer, a cooler, a nitrogen gas inflow pipe and a gas outflow pipe, and the viscosity of which both molecular chain ends were blocked with vinyl groups. Was charged with 1,300 g of dimethylpolysiloxane of 5,400 mPa · s and 500 g of toluene.
Azeotropic dehydration was carried out at ˜130 ° C. for 1 hour. After cooling to 100 ° C., 18 g of γ-mercaptopropylmethyldimethoxysilane, 1.0 g of 2,2′-azobis (2-methylbutyronitrile) (V-59 manufactured by Wako Pure Chemical Industries, Ltd.),
And a mixture of 10 g of toluene were added dropwise. After completion of the dropping, aging was carried out at 100 ° C. for 2 hours, and after completion of the aging, toluene was distilled off under reduced pressure to obtain 1,150 g of a colorless transparent liquid having a viscosity of 7,800 mPa · s and a nonvolatile content of 99.3%.
When 100 g of this colorless and transparent liquid was mixed with 1 g of tetrabutyl titanate, the viscosity did not increase immediately and it was cured after 1 day. Therefore, the vinyl group at the end of the polymer has γ
-It can be confirmed that mercaptopropylmethyldimethoxysilane has been added. The reaction formula of Example 4 is as follows.

[0027]

[Chemical 3]

[Embodiment 5] A four-necked flask having an internal volume of 2 liters equipped with a thermometer, a stirrer, a cooler, a nitrogen gas inflow pipe and a gas outflow pipe, and a viscosity in which both ends of the molecular chain were blocked with trivinyl groups. 1,300 g of dimethylpolysiloxane of 100,000 mPa · s and 500 g of toluene were charged, and azeotropic dehydration was carried out at 120 to 130 ° C. for 1 hour. 10
After cooling to 0 ° C., 24 g of γ-mercaptopropyltrimethoxysilane and 2,2′-azobis (2-methylbutyronitrile) (V-59 manufactured by Wako Pure Chemical Industries, Ltd.) were added to 1.
A mixture of 0 g and 10 g of toluene was added dropwise. After completion of the dropping, aging is carried out at 100 ° C. for 2 hours, and after completion of the aging, toluene is distilled off under reduced pressure to obtain a viscosity of 128,000 mPas.
・ S, 1,060% colorless and transparent liquid with non-volatile content of 99.5%
g was obtained. When 100 g of this colorless transparent liquid was mixed with 1 g of tetrabutyl titanate, the viscosity did not immediately increase,
It hardened after 1 day. From this, it can be confirmed that γ-mercaptopropyltrimethoxysilane was added to the vinyl group at the polymer terminal. The reaction formula of Example 5 is as follows.

[0029]

[Chemical 4]

[0030]

Industrial Applicability According to the present invention, organooxy-terminated organopolysiloxane can be industrially advantageously produced.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsuneo Kimura             Gunma Prefecture Usui District, Matsuida Town             Shin-Etsu Chemical Co., Ltd. Silicone electronic materials             Inside the technical laboratory F-term (reference) 4J035 BA02 CA06M CA061 CA14U                       CA141 CA25M CA26M CA261                       FB01 FB02 FB03 LA02 LA04                       LB20

Claims (4)

[Claims] 1. (A) a diorganopolysiloxane having an alkenyl group at the terminal and (B) the following general formula (1) (R ¹ O) _a R ² _3-a Si—R ³ —SH (1) (formula In the formula, R ¹ is a monovalent hydrocarbon group having 1 to 8 carbon atoms or an alkoxy group-substituted monovalent hydrocarbon group, R ² is a monovalent hydrocarbon group having 1 to 13 carbon atoms, and R ³ is a monovalent hydrocarbon group having 1 to 6 carbon atoms. Which is a divalent hydrocarbon group, a is an integer of 1 to 3), and is reacted with a mercapto group-containing organooxysilane represented by the formula (1) in the presence of a radical generator. Method for producing siloxane. 2. The component (A) is represented by the following general formula (2) R ⁴ ₃ SiO (R ⁵ ₂ SiO) _n SiR ⁴ ₃ (2) (wherein R ⁴ is the same or different and has 1 to 6 carbon atoms). Is a monovalent hydrocarbon group, at least one of R ⁴ is an alkenyl group, and R ⁵ is a monovalent hydrocarbon group having 1 to 13 carbon atoms.
n is an integer of 10 or more. The method according to claim 1, which is a diorganopolysiloxane represented by the formula (1). 3. The method according to claim 1, wherein the component (B) is mercaptopropyl monoalkyldialkoxysilane or mercaptopropyltrialkoxysilane. 4. An organooxy-terminated organopolysiloxane obtained by the method according to any one of claims 1 to 3.