JP3468685B2 - Carborane-containing silicon-based polymer and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel carborane-containing silicon polymer useful as a functional material having excellent heat resistance and flame retardancy, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, silicon-based polymers having excellent heat resistance and flame retardancy have been developed. In addition, attempts have been made to increase the molecular weight and improve the mechanical strength by a method of crosslinking a polymer by a polymer reaction [Organometallics, 15, 75 (1996)].
However, heat resistance and flame retardancy were not always sufficient. On the other hand, some carborane-containing silicon-based polymers are known, for example, J. Macromol. Sci.
v. Macromol. Chem., C17 (2), 173-208 (1979),
Poly (dodecacarborane-siloxane) has been reported.

In addition, Japanese Patent Publication No. 8-505649 discloses an organic boron polymer, and it is reported that the thermal stability of a siloxane polymer is improved by introducing carborane. However, the above-mentioned organoboron polymer is obtained from a reaction of an acetylene group-containing dilithio salt and a carbolane siloxane containing chloro groups at both ends, and it takes several steps to synthesize a carborane-containing silicon compound from a monomer. It wasn't the way.

In addition to the above-mentioned conventional organic boron polymers, almost no carborane-containing silicon polymer is known, and development of a novel carborane-containing silicon polymer having excellent heat resistance is expected.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel carborane-containing silicon polymer having excellent heat resistance and flame retardancy and a method for producing the same.

[0006]

In the present invention, an attempt was made to complex a silicon-based polymer having a reactive double bond group in its side chain with a silyl-substituted carborane derivative. The reaction between the double bond and the silyl group is very efficient, and the carborane can be easily introduced into the polymer. Further, since a reactive double bond is bonded to the side chain of the polymer, more carborane can be efficiently introduced, and further improvement in heat resistance and flame retardancy of the polymer can be expected.

The carborane-containing silicon-based polymer of the invention according to claim 1 (hereinafter referred to as the present invention 1 ) has the general formula (1):
And / or a hydrocarbon group comprising a combination of the carborane-containing unit represented by the general formula (2), the units represented by the general formulas (4) to (7), and the hydrocarbon group represented by the general formula (14).
And a phenylmethylsilylene group having a weight average molecular weight of 500 or more.

The method for producing a carborane-containing silicon polymer according to the second aspect of the present invention (hereinafter referred to as the present invention 2 ) is the method for producing a carborane-containing silicon polymer according to the first aspect of the present invention. ) To (7), a hydrocarbon group comprising a combination of units represented by the formulas (7) to (7) and a group represented by the general formula (14).
Formula in silicon-based polymer comprising a silylene group represented by E sulfonyl silylene group and the general formula (8) (8)
The double bond therein is reacted with the silyl-substituted carborane derivative represented by the general formula (9) or (10).

The present invention will be described in detail below.

The carborane-containing silicon polymer of the present invention 1 is represented by the carborane-containing unit represented by the general formula (1) and / or the general formula (2) and the general formulas (4) to (7). Hydrocarbon group consisting of a combination of units and general
From the phenylmethylsilylene group represented by the formula (14)
Become

[0011]

[Chemical 12]

[0012]

[Chemical 13]

[0013]

[Chemical 14]

[0014]

[Chemical 15]

In the formulas (1) and (2), R ¹ represents a hydrogen atom bonded to a silicon atom, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms, each of which is the same. May also be different. R ² is bonded to a silicon atom
C1-C20 alkylene group or C6-C30
Of represents an arylene group, it is not always necessary, stomach
In this case, CH ₂ —CH ₂ is directly bonded to the silicon atom . R
³ represents a hydrogen atom bonded to a carbon atom of carborane, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a silicon compound represented by the general formula (3). CB
xHx'C represents carborane which is a divalent cage boron compound, and x and x'represent an integer of 3 to 16. In formulas (4) and (5), R ⁵ represents a hydrogen atom bonded to a carbon atom, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms, and they may be the same or different. May be. In formula (7), R ⁶ represents an arylene group having 6 to 30 carbon atoms.

[0016]

[Chemical 16]

In the formula (3), R ⁴ is a hydrogen atom bonded to a silicon atom, an alkyl group having 1 to 20 carbon atoms or 6 carbon atoms.
To 30 aryl groups, which may be the same or different.

When the number of carbon atoms of the hydrocarbon group represented by R ^{1 to} R ⁴ is aliphatic, the bond is easily broken and the heat resistance is lowered, and when it is aromatic, the number of carbon atoms to the solvent is increased. Since the solubility decreases, the above ranges are limited.

Examples of the alkyl group represented by R ¹ , R ³ and R ⁴ include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group,
Examples thereof include an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group and an eicosyl group.

Examples of the aryl group represented by R ¹ , R ³ and R ⁴ include a phenyl group, a tolyl group, a xylyl group, a biphenyl group and a naphthyl group.

Examples of the alkylene group represented by R ² include methylene group, ethylene group, propylene group,
Butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tricylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group, nonadecylene group, eicosylene group Etc.

The arylene group represented by R ² is, for example, a phenylene group, a tolylene group, a xylene group,
Examples thereof include a biphenylene group, a naphthalenylene group, and an anthracenylene group.

Examples of the carborane represented by CBxHx'C include dodecacarborane, decacarborane, heptacarborane, hexacarborane and pentacarborane.

As the hydrocarbon group represented by R ^{1 to} R ⁴ and the carborane represented by CBxHx'C, the same components can be mentioned hereinafter.

Examples of the hydrocarbon group composed of a combination of the units represented by the above general formulas (4) to (7) include those shown below.

[0026]

[Chemical 17]

Examples of the alkyl group and aryl group represented by R ⁵ include the same alkyl groups and aryl groups as those described above for R ^1, and the same applies to the following. Also, the above R
Examples of the arylene group represented by ⁶ include the same arylene groups as those described above for R ^2, and the same applies to the following.

Specific examples of the hydrocarbon group comprising the combination of the above (4) to (7) include, for example, methylene group, ethylene group, propylene group, methylmethylene group, methylethylene group, dimethylmethylene group, dimethylethylene. Group, vinylene group, butylene-1,3-diene group , ethynylene group, dietynylene group, phenylene group, biphenylene group,
Naphthalenylene group, propylene-1-ene group, butylene-2-ene group, pentylene-1,4-diene group, propylene-1-yne group, butylene-2-yne group, pentylene-1,4-diyne group, methylene Phenylene group, 1,4-
Dimethylenebenzene group, diphenylenemethane group, vinylenephenylene group, 1,4-divinylenebenzene group, 1,
Examples thereof include a 2-diphenylenevinylene group, an ethynylenephenylene group, a 1,4-diethynylenebenzene group, and a diphenyleneacetylene group.

The weight average molecular weight of the silicon-based polymer of the present invention 1 is limited to 500 or more because sufficient heat resistance cannot be obtained when the weight average molecular weight becomes small. The upper limit of the weight average molecular weight is not particularly limited, but if it is too large, the solubility decreases and it becomes difficult to obtain a molded product, so 5 million or less is preferable.

Next, the present invention 2 will be described. The present invention
In the method for producing a carborane-containing silicon-based polymer of No. 2, a hydrocarbon group composed of a combination of units represented by the general formulas (4) to (7) and a phenylene polymer represented by the general formula (14).
A silylene group represented by Chirushiriren groups and the general formula (8)
To react the double bond in the general formula (8) in the silicon-based polymer consisting of the silyl-substituted carborane derivative represented by the general formula (9) or (10).
A carborane-containing silicon-based polymer of No. 1 is obtained.

[0031]

[Chemical 18]

[0032]

[Chemical 19]

[0033]

[Chemical 20]

[0034]

[Chemical 21]

[0035]

[Chemical formula 22]

In the formula, R ¹ is a hydrogen atom bonded to a silicon atom, an alkyl group having 1 to 20 carbon atoms or 6 to 30 carbon atoms.
Represents an aryl group and may be the same or different. R ³ is a hydrogen atom bonded to a carbon atom of carborane, an alkyl group having 1 to 20 carbon atoms, or a carbon atom having 6 to ³ carbon atoms.
Represents an aryl group of 0 or a silicon compound represented by the general formula (3). CBxHx'C represents carborane which is a divalent cage boron compound, and x and x'represent an integer of 3 to 16. R ⁵ represents a hydrogen atom bonded to a carbon atom, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms, and may be the same or different. R ⁶ represents an arylene group having 6 to 30 carbon atoms. R
⁷ represents an alkylene group having 1 to 20 carbon atoms or an arylene group having 6 to 30 carbon atoms bonded to a silicon atom, but it is not always necessary, and if not present, a double bond group is directly bonded to the silicon atom.

[0037]

[Chemical formula 23]

In the formula, R ⁴ is a hydrogen atom bonded to a silicon atom, an alkyl group having 1 to 20 carbon atoms or 6 to 30 carbon atoms.
Represents an aryl group and may be the same or different.

Specific examples of the hydrocarbon group composed of the combination of the above (4) to (7) include the same ones as those of the first invention.

Examples of the silylene group represented by the above general formula (8) include methyl vinyl silylene, ethyl vinyl silylene, propyl vinyl silylene, butyl vinyl silylene, pentyl vinyl silylene, hexyl vinyl silylene, phenyl vinyl silylene and tolyl vinyl. Silylene,
Xylyl vinyl silylene, methyl allyl silylene, ethyl allyl silylene, propyl allyl silylene, butyl allyl silylene, pentyl allyl silylene, hexyl allyl silylene, phenyl allyl silylene, tolyl allyl silylene, xylyl allyl silylene, methyl propenyl silylene, ethyl propenyl silylene, Propylpropenylsilylene, butylpropenylsilylene, pentylpropenylsilylene, hexylpropenylsilylene, phenylpropenylsilylene, tolylpropenylsilylene, xylylpropenylsilylene, methylbutenylsilylene,
Ethyl butenyl silylene, propyl butenyl silylene,
Butyl butenyl silylene, pentyl butenyl silylene,
Hexyl butenyl silylene, phenyl butenyl silylene, tolyl butenyl silylene, xylyl butenyl silylene and the like can be mentioned.

Examples of the silyl-substituted carborane derivative represented by the above general formula ( 10 ) include dimethylsilylcarborane, diethylsilylcarborane, dipropylsilylcarborane, dibutylsilylcarborane, dipentylsilylcarborane, dihexylsilylcarborane and diphenylsilylcarborane. , Ditolylsilylcarborane, dixylylsilylcarborane, dibiphenylsilylcarborane, dinaphthylsilylcarborane, dianthracenylsilylcarborane, methylethylsilylcarborane, methylpropylsilylcarborane, methylbutylsilylcarborane, methylpentylsilylcarborane, methylhexylsilyl Carborane, ethylpropylsilylcarborane, ethylbutylsilylcarborane, ethylpentylsilylcarborane , Ethylhexylsilylcarborane,
Propylbutylsilylcarborane, propylpentylsilylcarborane, propylhexylsilylcarborane,
Examples thereof include butylpentylsilylcarborane, butylhexylsilylcarborane, pentylhexylsilylcarborane, methylphenylsilylcarborane, ethylphenylsilylcarborane, propylphenylsilylcarborane, butylphenylsilylcarborane, pentylphenylsilylcarborane and hexylphenylsilylcarborane.

Examples of the silyl-substituted carborane derivative represented by the above general formula ( 9 ) include m-bis (dimethylsilyl) carborane, m-bis (diethylsilyl) carborane, m-bis (dipropylsilyl) carborane, m
-Bis (dibutylsilyl) carborane, m-bis (dipentylsilyl) carborane, m-bis (dihexylsilyl) carborane, m-bis (diphenylsilyl) carborane, m-bis (ditolylsilyl) carborane, m-bis (dixylylsilyl) carborane , M-bis (dibiphenylsilyl) carborane, m-bis (dinaphthylsilyl) carborane, m-bis (dianthracenylsilyl)
Carborane, m-bis (methylethylsilyl) carborane, m-bis (methylpropylsilyl) carborane, m
-Bis (methylbutylsilyl) carborane, m-bis (methylpentylsilyl) carborane, m-bis (methylhexylsilyl) carborane, m-bis (ethylpropylsilyl) carborane, m-bis (ethylbutylsilyl) carborane, m -Bis (ethylpentylsilyl) carborane, m-bis (ethylhexylsilyl) carborane, m-bis (propylbutylsilyl) carborane, m
-Bis (propylpentylsilyl) carborane, m-bis (propylhexylsilyl) carborane, m-bis (pentylhexylsilyl) carborane, m-bis (methylphenylsilyl) carborane, m-bis (ethylphenylsilyl) carborane, m -Bis (propylphenylsilyl) carborane, m-bis (butylphenylsilyl) carborane, m-bis (pentylphenylsilyl)
Examples thereof include carborane, m-bis (hexylphenylsilyl) carborane, and o- and p-isomers thereof.

Examples of the catalyst used in the reaction in the production method of the present invention 2 include, but are not limited to, chloroplatinic acid, hexarodium hexadecacarbonyl, bis (divinyltetramethyldisiloxane) platinum and the like. Not something. When the amount of the catalyst used is too small, the reaction does not proceed sufficiently, and when the amount is too large, the catalyst tends to remain in the polymer after synthesis, and the heat resistance decreases due to the residual, so that the general formula (8) and the general formula (4) are used. ) To (7) is preferably 0.001 to 20 mol% and more preferably 0.01 to 10 mol% with respect to the constitutional unit of the silicon-based polymer.

The molar ratio of the silicon-based polymer used in the above reaction to the silyl-substituted carborane derivative is such that the heat resistance and flame retardancy of the resulting polymer do not improve so much when the introduction amount of carborane is small. Combined: silyl-substituted carborane derivative = 1: 0.01 to 20 is preferable, and 1: 0.1 to 10 is more preferable.

The solvent used in the above reaction may be polar or nonpolar, but is preferably an aprotic solvent such as toluene or tetrahydrofuran. The amount of the solvent used is 0.01 to 5 in terms of the concentration of the constituent unit of the silicon-based polymer.
0 mol / L is preferable, and more preferably 0.05 to 5
It is mol / L.

The above reaction is preferably carried out between room temperature and the boiling point of the solvent. Further, this reaction can be carried out in air or in an inert gas atmosphere, but is preferably in an argon gas or nitrogen gas atmosphere.

When the reaction time of the above reaction becomes short, the carborane introduction reaction does not proceed sufficiently, and the heat resistance of the resulting polymer is not improved. It will not melt and will be difficult to handle, and
Since the heat resistance decreases, 1 to 72 hours is preferable. After the reaction is completed, the silicon-based polymer can be purified by a reprecipitation method or gel permeation chromatography (GP
Examples include sorting by C).

[0048]

Embodiments of the present invention will be described below.

(Example 1) 1,4-diethynylbenzene 15.1 was placed in a 1 L four-necked flask equipped with a reflux tube replaced with argon and a dropping funnel reflux tube.
4 g (120.0 mmol) was added and dissolved in 500 mL of tetrahydrofuran. After cooling the flask with a dry ice / methanol bath, 150 mL of a hexane solution of n-butyllithium (1.6 mol / L) was added dropwise over 45 minutes, and the mixture was stirred for 1 hour. Then, 12.19 g (60.0 mmol) of phenylvinyldichlorosilane and methyl
Phenyldichlorosilane 11.47 g (60.0 mmo
120 mL of a tetrahydrofuran mixed solution of 1) was added dropwise over 30 minutes, and the mixture was stirred at room temperature for 24 hours. The obtained reaction solution was poured into 500 mL of a saturated aqueous solution of ammonium chloride and stirred for several minutes, and then the tetrahydrofuran layer was separated. The aqueous layer was extracted 3 times with diethyl ether, and the organic layers were combined and dried over anhydrous magnesium sulfate. The organic solvent was concentrated and poured into 1.8 L of methanol, and then the precipitate was filtered off to obtain poly (1,4-diethynylbenzene / phenylvinylsilylene / methylphenylsilylene) as a yellowish white powder (polymer). 21.75 g was obtained.

500 mL of 3 with a reflux tube replaced with argon
Into a one-necked flask, 10.02 g (20.0 mmol) of the above poly (1,4-diethynylbenzene / phenylvinylsilylene / methylphenylsilylene) was placed, dissolved in 300 ml of toluene and then heated to 50 ° C, 10m
mol of catalyst [bis (divinyltetramethyldisiloxane) platinum] _{{Pt [CH 2 = CHSi (} CH 3) 2 OSi
(CH ₃ ) ₂ CH = CH ₂ ] ₂ } in toluene solution was added, and 1
Stir for 0 minutes. Then, 2.61 g (10.2 mmol) of 1,7-bis (dimethylsilyl) dodecacarborane
25 ml of the toluene solution of was added dropwise, the temperature of the oil bath was raised to 120 ° C., and the mixture was heated under reflux for 10 hours. Further, the reaction solution was distilled off under reduced pressure and then added to 2 L of methanol.
The resulting precipitate was filtered off and a yellowish white powder (polymer) 1
1.2 g was obtained. The weight average molecular weight of this polymer was 41,200 in terms of polystyrene.

¹ H- NMR spectrum ("Bruker""D" , measured on the yellowish white powder of Example 1 above)
1 ) and IR spectrum (measured with "FTS135 system" manufactured by Bio-Rad) are shown in FIG. 2 , respectively.

[0052] In Figure 1, the peak of the proton on the basis of the carborane is seen over the 0.7~4ppm. Also,
A proton peak of a methyl group and a methylene group bonded to a silicon atom was confirmed at 0.07 to 0.6 ppm, and a proton peak of a phenyl group was confirmed at 7 to 8 ppm. Further, in FIG. 2, absorption was observed due to the carborane to 2594cm ^-1, the polymer obtained in Example 1 from these things, in the carborane-containing silicon-based polymer represented by the formula (12) I confirmed that there is.

[0053]

[Chemical formula 24]

Comparative Example 1 0.51 g (2.0 mmol) of poly (1,3-diethynylbenzene / phenylvinylsilane) was placed in a 100-ml two-necked flask equipped with a reflux tube replaced with argon, and dissolved in 10 ml of tetrahydrofuran. Then, the temperature of the reaction solution was raised to 55 ° C., and the catalyst (H ₂ PtCl ₆ .6H ₂ O) 0.005 was added.
1 mL of isopropanol solution of g (0.01 mmol)
Was charged and stirred for 10 minutes. Subsequently, 0.19 g (1.0 mmol) of 1,4-bis (dimethylsilyl) benzene
5 mL of a tetrahydrofuran solution of was added dropwise, the temperature of the oil bath was raised to 75 ° C., and the mixture was heated under reflux for 10 hours. Next, the reaction solution is cooled to room temperature, and 500 ml of methanol is added.
I put it in. The obtained precipitate was separated by filtration to obtain 0.478 g of a yellowish white powder (polymer).

The obtained polymer was subjected to ¹ H-NMR spectrum measurement and IR spectrum measurement as in Example 1 to confirm that the polymer was a silicon-based polymer represented by the formula (13).

[0056]

[Chemical 25]

[0057] The thermogravimetric analysis of Example 1 obtained in 及 beauty Comparative Example 1 polymer was measured using a Seiko Denshi "SSC5200 System", showing the measurement results in FIG.
Table 1 shows the 5 wt% decomposition temperature (Td ₅ ) in an air atmosphere and the weight residual rate (W ₈₀₀ ) at 800 ° C.

[0058]

[Table 1]

From Table 1, it can be seen that the carborane-containing silicon polymer of Example 1 is a material having very excellent heat resistance.

[0060]

EFFECTS OF THE INVENTION The silicon-based polymer of the present invention is as described above, has excellent heat resistance, and is suitably used for space / aviation materials, building materials and the like.

[Brief description of drawings]

1 is a ¹ H-NMR spectrum of the silicon-based polymer of Example 1.

2 is an IR spectrum of the silicon-based polymer of Example 1. FIG.

[Figure 3] Ru pyrolysis curve der silicon-based polymer of Example 1及 beauty Comparative Example 1.

Continuation of the front page (56) Reference JP-A-11-1561 (JP, A) JP-A-11-240956 (JP, A) JP-A-11-240957 (JP, A) JP-A-50-44299 (JP , A) JP-A-5-262878 (JP, A) JP-A-6-49430 (JP, A) JP-A-6-172712 (JP, A) JP-B 44-2240 (JP, B1) JP-A 8-505649 (JP, A) Special Table 8-507795 (JP, A) Special Table 10-509750 (JP, A) US Patent 3388090 (US, A) US Patent 3388091 (US, A) US Patent 5552505 ( (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 77/00-77/62 C08G 79/00-79/14 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A hydrocarbon group comprising a combination of a carborane-containing unit represented by the general formula (1) and / or a general formula (2) and a unit represented by the general formulas (4) to (7). Phenylmethyl represented by the general formula (14)
A carborane-containing silicon polymer comprising a silylene group and having a weight average molecular weight of 500 or more. [Chemical 1] [Chemical 2] [Chemical 3] [Chemical 4] [In the formula, R ¹ represents a hydrogen atom bonded to a silicon atom, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms, and may be the same or different. R ² is an alkyl group having 1 to 20 carbon atoms bonded to a silicon atom.
Represents a alkylene group or an arylene group having 6 to 30 carbon atoms
However, it is not absolutely necessary, and if not, directly on the silicon atom
CH ₂ -CH ₂ is bonded. R ³ represents a hydrogen atom bonded to a carbon atom of carborane, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a silicon compound represented by the general formula (3). CBxHx'C represents carborane which is a divalent cage boron compound, and x,
x'represents an integer of 3 to 16. R ⁵ represents a hydrogen atom bonded to a carbon atom, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms, and may be the same or different. R ⁶ represents an arylene group having 6 to 30 carbon atoms] (In the formula, R ⁴ represents a hydrogen atom bonded to a silicon atom, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms, and may be the same or different) 2. A hydrocarbon group comprising a combination of units represented by general formulas (4) to (7) and a hydrocarbon group represented by general formula (14).
Represented by the general formula (9) or (10), and the double bond in the general formula (8) in the silicon-based polymer comprising the phenylmethylsilylene group represented by the formula and the silylene group represented by the general formula (8) method for producing a carborane-containing silicon-based polymer of claim 1 Symbol placement, characterized by reacting a that silyl-substituted carborane derivative. [Chemical 6] [Chemical 7] [Chemical 8] [Chemical 9] [Chemical 10] [In the formula, R ¹ represents a hydrogen atom bonded to a silicon atom, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms, and may be the same or different. R ³ represents a hydrogen atom bonded to a carbon atom of carborane, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a silicon compound represented by the general formula (3). CBxHx'C represents carborane which is a divalent cage boron compound, and x and x'represent an integer of 3 to 16. R ⁵ is a hydrogen atom bonded to a carbon atom, having 1 to 1 carbon atoms.
It represents an alkyl group having 20 or an aryl group having 6 to 30 carbon atoms, which may be the same or different. R ⁶
Represents an arylene group having 6 to 30 carbon atoms. R ⁷ represents an alkylene group having 1 to 20 carbon atoms or an arylene group having 6 to 30 carbon atoms bonded to a silicon atom, but it is not always necessary, and if not present, a double bond group is directly bonded to the silicon atom. [Chemical 11] (In the formula, R ⁴ represents a hydrogen atom bonded to a silicon atom, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms, and may be the same or different)