JP2000248180A - Preparation of poly(phenylsil sesquioxane) - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solvent-soluble polymer by dehydrating-condensation of 1,3,5,7-tetraphenyl cyclotetrasiloxane-1,3,5,7-tetraol in a solvent. SOLUTION: A tetraol of formula I (wherein Ph is phenyl) is used as a source material. The tetraol of formula I can be synthesized by hydrating phenyltrichlorosilane in water. A poly(phenylsil sesquioxane) of a ladder structure is obtained by dissolving the tetraol, as the source material into a solvent to obtain a solution and mixing preferably with an addition of a base to drive dehydrating-condensation slowly. The solvent to be used is preferably the one that can easily dissolve the cyclic tetramer, the source material, but can hardly dissolve the ladder polymer to be formed. The base is preferably added in an amount of 10-5,000 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a silicone having a so-called ladder-type structure, which has excellent heat resistance and electrical insulation properties and exhibits particularly excellent properties of coating properties and crack resistance, and is highly controlled in structure. The present invention relates to a method for producing a resin [poly (phenylsilsesquioxane)].

[0002]

2. Description of the Related Art Poly (phenylsilsesquioxane) resin is used for coating materials, sealing materials, interlayer insulating films and the like because of its excellent heat resistance and electric insulation. ing. Such a resin is usually synthesized by hydrolyzing a silane having a hydrolyzable group such as phenyltrichlorosilane or phenyltrialkoxysilane. It has a structure bonded to

[0003] Such randomly bonded poly (phenylsilsesquioxane) is insufficiently condensed,
In a state where a considerable amount of silanol groups or alkoxy groups remain on silicon atoms, although it has solubility in organic solvents, if condensation is further promoted to increase the molecular weight, three-dimensional cross-linking proceeds and solvent-insoluble gels It has a drawback that it becomes a shape.

However, since poly (phenylsilsesquioxane) is trifunctional, it can form a ladder-like structure called a ladder polymer represented by the following formula (2). Because such polymers have a linear structure, they are highly condensed,
It is characterized by being soluble in organic solvents.

[0005]

Embedded image (However, n represents a positive integer in the formula.)

[0006] Such a ladder polymer has a highly bonded and dense structure, so that the heat resistance is further improved, and the dielectric constant is lowered due to a decrease in polar substituents such as a hydroxyl group and an alkoxy group. However, it is expected that a high electrical insulation property can be obtained, and a synthesis method thereof has been studied.

In 1960, Brown et al. Of GE showed that a ladder polymer can be synthesized by subjecting a prepolymer obtained by hydrolyzing phenyltrichlorosilane to heat condensation in a high boiling solvent using potassium hydroxide as a condensation catalyst. (J. Am. Chem. Soc. 82, 6
194 (1960)).

[0008] However, this method has the drawbacks that it is difficult to control the reaction and it is difficult to synthesize a large amount, and the polymer thus obtained generally has a wide molecular weight distribution and contains a high molecular weight component. Since it is soluble only in very limited solvents such as benzene and tetrahydrofuran and hardly soluble in toluene, it is almost impossible to form a uniform thin film by spin coating in a solution state. difficult.

Furthermore, the polymer obtained by this method is considered to contain a portion having no substantial ladder structure in the molecule due to the extreme reaction conditions. It is considered difficult.

[0010] Since then, many groups have proposed the synthesis of ladder polymers, but they are basically an extension of the above method. For example, Kimura et al. Hydrolyze phenylsilanetriol in an organic solvent to obtain a prepolymer, and heat-treat the prepolymer to obtain a ladder polymer (JP-A-8-143578). However, since the condensation itself is a similar method, it has the same problems as described above.

The present invention has solved the above-mentioned problems, and provides a method for producing a poly (phenylsilsesquioxane) having a ladder structure as shown in the above formula (2), which is highly controlled in structure. The purpose is to do.

[0012]

Means for Solving the Problems and Embodiments of the Invention In view of such circumstances, the present inventors have studied a method for efficiently synthesizing a ladder polymer whose structure is strictly controlled. For this purpose, a method for producing the polymer by condensing the reaction under as mild a reaction condition as possible was studied.
As a result, surprisingly, 1,3,5,7-tetraphenylcyclotetra represented by the following formula (1) is known which can be synthesized by hydrolyzing phenyltrichlorosilane in water. Siloxane-1,3,5,7-
When tetraol was used as a raw material, dehydration condensation proceeded in a solvent under extremely mild conditions, and it became clear that a ladder polymer could be synthesized.

[0013]

Embedded image (In the formula, Ph represents a phenyl group.)

Accordingly, the present invention provides a method of formula (1)
3,5,7-tetraphenylcyclotetrasiloxane-
Provided is a method for producing a solvent-soluble silicone resin [poly (phenylsilsesquioxane)], which comprises using 1,3,5,7-tetraol as a raw material and performing dehydration condensation in a solvent.

Hereinafter, the present invention will be described in more detail. The method for producing poly (phenylsilsesquioxane) of the present invention comprises, as described above, 1,3,3 of the above formula (1).
5,7-tetraphenylcyclotetrasiloxane-1,
3,5,7-tetraol is used as a raw material. The synthesis of 1,3,5,7-tetraphenylcyclotetrasiloxane-1,3,5,7-tetraol used as this raw material was described by Brown et al. Am. Che
m. Soc. 87, 4317 (1965), which can be isolated as a crystalline powder by reproducing the experiment described therein.

In the present invention, the raw material tetraol is dissolved in a solvent to form a solution, to which a base is preferably added, followed by stirring. 2) The silicone resin [poly (phenylsilsesquioxane)] is formed.

Here, the solvent used in the reaction includes:
Although not particularly limited, 1,3,5,7-tetraphenylcyclotetrasiloxane-1,3,5,7-
Any substance that can dissolve tetraol can be used. Specific examples include methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-2-propanol, 1-butanol, 2-butanol, acetone, 2-butanone, 2-hexanone, tetrahydrofuran, dioxane, ethyl acetate, Acetic acid-1-
Butyl, isobutyl acetate, acetonitrile, N, N-
Examples include dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide and the like.

In this case, the solvent used at this time is
Although the cyclic tetramer as a raw material dissolves, the ladder polymer formed by condensation is preferably difficult to dissolve. Acetone, 2-butanone, dioxane, ethyl acetate, acetonitrile, tetrahydrofuran, N, N-dimethylacetamide Are preferred.

The dehydration-condensation reaction preferably involves adding a trace amount of a base to the solution, and proceeds by stirring at room temperature. The amount of the base to be added is usually 100 ppm. However, when the reaction system itself is acidic, for example, when the raw material contains an acidic substance, a sufficient base for neutralization is required. Usually, the amount of the base actually used is preferably in the range of 10 to 5000 ppm, but is not limited thereto. If too much base is used,
There is a possibility that a decomposition of the cyclic tetramer itself as a raw material partially occurs to form a gel insoluble in a solvent.

The base used is not particularly limited as long as it is a basic substance. For example, sodium hydroxide, potassium hydroxide, ammonium hydroxide, N, N,
Alkalis such as N, N-tetramethylammonium hydroxide, triethylamine, tributylamine,
Dimethylaniline, di-iso-propylamine, N,
N-diethylcyclohexylamine, 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo [5.4.0] undec-7-ene, 2,5-diazabicyclo [2.2.1] Amines such as heptane are mentioned as specific examples.

The resulting silicone resin usually dissolves at the beginning, but the solubility is reduced due to the increase in molecular weight, and a precipitate is formed. The time required during this period varies from several minutes to several hours, depending on conditions. To complete the reaction sufficiently, the reaction time is about 24 to 100 hours,
The desired resin is separated by filtration. However, a precipitate is not formed depending on the solvent used. In this case, after a sufficient reaction time has elapsed, a solvent that does not dissolve the resin such as methanol or hexane is added to make the resin insoluble, and then separated by filtration. The silicone resin isolated at this time is almost quantitative in yield.

The molecular weight and molecular weight distribution of the produced silicone resin can be determined by gel permeation chromatography (GPC).
As a result of an experiment repeatedly performed in the present invention, the number average molecular weight (Mn) was 100 as a polystyrene equivalent molecular weight.
0 to 200,000, weight average molecular weight (Mw) of 1000
５００500,000, and the molecular weight distribution is 1.0-5.0, usually about 1.5-2.5.

The fact that the silicone resin thus obtained has a ladder structure represented by the formula (2) means that, first, in the infrared absorption spectrum (IR), the silicone resin has a ladder structure around 1100 cm ^-1 derived from a siloxane bond. Peak is 1040c
This is supported by the appearance of sharply split peaks around m ^-1 and 1130 cm ^-1 [Journal of Polymer Science (1963, C-1 vol. 83
page)].

Further, the silicone resin is easily dissolved in benzene and tetrahydrofuran, and in addition, toluene, propylene glycol monomethyl ether which can hardly be dissolved by a ladder polymer having a molecular weight of about 200,000 synthesized by the Brown method, for example. It also has a solubility of at least 10% or more at room temperature in acetate, ethyl lactate and cyclohexanone.
This indicates that the polymer has a regular bonding mode and supports a ladder structure.

Since the present polymer has high solubility in the solvents used for the resist materials as described above, it is possible to form a very uniform thin film by spin coating or the like. The thin film thus formed has an excellent property of not forming a crack as occurs in a silsesquioxane resin having a normal random structure.

Because of these features, the silicone resin is widely applied as a coating material, a sealing material, an interlayer insulating material for semiconductors, and the like.

[0027]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to the following examples.

[Synthesis Example 1] A solution of 25 g of phenyltrichlorosilane in 42.5 ml of acetone was slowly dropped over 30 minutes while stirring 940 g of ice water. After the completion of the dropwise addition, the mixture was further stirred for 1 hour, and left standing in a refrigerator at 0 ° C. for 48 hours. In the reaction solution, a white and slightly viscous solid was formed in the vessel wall and in water. After removing the water by decantation, it was washed with a small amount of pure water, further washed with carbon disulfide, and dried in vacuum. 8.06 g of white crystals were obtained as a residue (yield 49%). The crystals were analyzed by gel permeation chromatography to find that 95% of the components had a weight average molecular weight of about 580 in terms of polystyrene.
And 970, a mixture of 5% of components.
The molecular weight of 1,3,5,7-tetraphenylcyclotetrasiloxane-1,3,5,7-tetraol is calculated to be 5
52.5, indicating that the main component (95%) was a cyclic tetramer and that the dimer was contained as a minor component (5%).

Example 1 Crystal obtained in Synthesis Example 1
0 g was dissolved in 300 ml of acetone, and 0.1 g of triethylamine was added thereto, followed by stirring at room temperature. After about 10 minutes,
The homogenous solution became cloudy and after about 5 hours the stirring became difficult due to the viscous material formed. 48 as it is
When left for a while, the precipitated solid was solidified and the tackiness was lost. This was physically crushed, powdered, filtered, washed with acetone, and vacuum dried.
5.23 g were obtained as a powdery solid residue. This is a yield of 93, assuming that the dehydration condensation has completely progressed.
%. When analyzed by gel permeation chromatography, the weight average molecular weight (Mw) in terms of polystyrene was about 9230, the number average molecular weight (Mn) was about 5161, and the molecular weight distribution (Mw / Mn) was 1.7.
Nine. In addition, this compound has an absorption of Si-OH at 3450 cm ⁻¹ in an infrared absorption spectrum,
Absorption of siloxane bonds split at 1043 cm ^-1 and 1132 cm ^-1 appears, indicating that the polymer has a ladder structure (reference: RH Rane).
y, M. Itoh, A .; Sakakibara &
T. Suzuki, Chem. Rev .. 95 , 1409
(1995)).

Example 2 A reaction similar to that of Example 1 was carried out by reducing the reaction scale to 1/3 by using methanol as a solvent instead of acetone and using 15 ppm of potassium hydroxide with respect to the solvent instead of triethylamine as a base. I went. As a result, 1.55 g of a silicone resin was obtained.
Mn of this polymer was about 3650 and Mw was 9000.

Example 3 Example 2 was repeated using 2-butanone as a solvent instead of acetone and using 10-ppm 1,4-diazabicyclo [2.2.2] octane as a base instead of triethylamine. The same reaction as in Example 1 was performed by reducing the reaction scale to 1/3. As a result, 1.62 g of a silicone resin was obtained. Mn of this polymer
Was about 5100 and Mw was 16700.

Example 4 A reaction similar to that of Example 1 was carried out with a reaction scale of 1/3 using tetrahydrofuran instead of acetone as a solvent and 200 ppm of triethylamine as a base. As a result, 1.60 g of a silicone resin was obtained. Mn of this polymer was about 6,300 and Mw was 17,200.

Example 5 Acetonitrile was used as the solvent instead of acetone, and the base was tetramethylammonium hydroxide instead of triethylamine.
Using 1 ml of a 38% aqueous solution, the same reaction as in Example 1 was performed with a reaction scale of 1/3. As a result, 1.70 g of a silicone resin was obtained. Mn of this polymer was about 5450 and Mw was 8,600.

Example 6 A reaction similar to that of Example 1 was carried out using N, N-dimethylacetamide in place of acetone as a solvent and 100 ppm of triethylamine as a base, with a reaction scale of 1/3. As a result, 1.48 g of a silicone resin was obtained. Mn of this polymer was about 12000 and Mw was 29,100.

[0035]

According to the present invention, heat resistance, electrical insulation,
It is possible to efficiently synthesize a silicone resin [poly (phenylsilsesquioxane)] having a ladder-type structure with a highly controlled structure and exhibiting properties excellent in coatability and crack resistance.

Claims (1)

[Claims] [Claim 1] The following formula (1) (In the formula, Ph represents a phenyl group.)
3,5,7-tetraphenylcyclotetrasiloxane-
A process for producing solvent-soluble poly (phenylsilsesquioxane), comprising using 1,3,5,7-tetraol as a raw material and performing dehydration condensation in a solvent.