JPH1121353A - Production of curable silicone resin and production of cured article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a curable silicone resin that has a good storage stability and gives a cured article having an elastic modulus not decreasing even at high temps. by subjecting an organotrihalosilane and a bifunctional diorganosilane or a diorganopolysiloxane having functional groups at both molecular ends to hydrolysis and condensation. SOLUTION: An organotrihalosilane of formula: RSiX3 (wherein R is a monovalent hydrocarbon group; and X is a halogen) and a bifunctional diorganosilane of formula: Y(SiR2 O)e SiR2 Y (wherein Y is a halogen, OH, or H; and e is 0-300) or a diorganopolysiloxane having functional groups at both molecular ends are subjected to hydrolysis and condensation in a two-phase reaction system comprising water and an oxygen-contg. org. solvent or a mixture of an oxygen- contg. org. solvent and a hydrocarbon solvent to give a curable silicone resin having an average structural formula represented by the formula [wherein a to d satisfy the relations: a+b+c+d=1, 0.001<=(a+b)/(c+d)<=1.0 and 0.12<=c/(c+d)<=0.35].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a curable silicone resin which gives a cured silicone resin having excellent physical thermal stability, and a method for producing the cured silicone resin.

[0002]

BACKGROUND OF THE INVENTION The present inventors have disclosed in WO 96/02292 and WO 96/02291 an oxygen-containing organic solvent or an organic solvent containing 50% by volume or less of a hydrocarbon solvent and 1 mole of halogen atoms in halosilane. In contrast, 1.8
Disclosed are methods for hydrolyzing and condensing methyltrihalosilane in a two-phase system with or without gram-equivalents of a water-soluble inorganic base or water with or without a salt of a buffering weak acid. According to this method, polymethylsilsesquioxane could be obtained without causing gelation. In addition, polymethylsilsesquioxanes obtained by conventional methods are commonly hard but brittle. However, WO 96/02292 and WO 96/022
The cured product of polymethylsilsesquioxane disclosed in No. 91 is unique in that it has flexibility and thermal stability (high thermal decomposition onset temperature) that were difficult to achieve with a conventional cured product of polymethylsilsesquioxane. It was characteristic.

An organotrichlorosilane and an equimolar amount thereof are used in a two-layer system with water, that is, a ketone as an organic solvent, that is, a reaction system in which these form an upper layer and a lower layer and have a wide plane interface therebetween. The following synthesis reaction of silicone resin by hydrolysis and condensation of a mixture with diorganodichlorosilane is disclosed in JP-A-50-111198. However, the amount of hydroxyl groups and the like of the product are not specified, and are not intended for the specific properties of the cured product described in the present invention. In addition, there was a poor operability that the stirring speed had to be adjusted so as to maintain two layers during the reaction.

[0004] The molar ratio between the organic groups on silicon and silicon is 1 to 1.
Patents specifying the hydroxyl group content of the silicone resin No. 8 include Canadian Patent No. 0868996, British Patent No. 1294196, JP-A-48-101444
(US Patent No. 3759867), Japanese Patent Application Laid-Open No.
No. -10700 (U.S. Pat. No. 4,056,492)
Which contain about 3 to 12% by weight of hydroxyl groups are disclosed, but all aim to increase the curing speed of the resin, but not to the thermal stability of the cured product. The Canadian patent no. 0868996, British Patent N
o. 1294196 and JP-A-48-101444 (US Patent No. 3759867) hydrolyze and condense halosilane to a mixture of water and an organic solvent insoluble in water in a system using acetone as a cosolvent.

As a polymer containing polyorganosilsesquioxane and diorganopolysiloxane as components, JP-A-3-31325 discloses a polyorganosilsesquioxane having a functional group such as a chlorine group at both terminals. A compound that reacts with a diorganopolysiloxane to block the silanol of the polyorganosilsesquioxane is disclosed. This is intended to improve the storage stability by reducing the number of silanol groups by blocking the silanol groups.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polyorganosilsesquioxane structure in a silicone resin containing a large amount of silanol groups, exhibiting extremely good storage stability, and exhibiting an elastic modulus even at high temperatures. It is to provide a cured silicone resin which does not decrease.

[0007] WO 96/02292 and WO 96
/ 02291, a polymethylsilsesquioxane could be obtained without gelation by a specific production method, and a flexible cured product of polymethylsilsesquioxane could be obtained.

As shown in the comparative examples of this specification, a conventional reaction system mainly comprising a hydrocarbon solvent and using an alcohol as a co-solvent to prevent gelation (for example, Japanese Patent Publication No.
A cured product of a silicone resin synthesized by hydrolyzing and condensing a mixture of methyltrichlorosilane and dimethyldichlorosilane according to U.S. Pat. No. 4,615,415 has poor physical heat stability (maintaining good physical properties even at high temperatures).

[0009]

SUMMARY OF THE INVENTION The present invention is a method for producing a curable silicone resin having an average structure represented by the following general formula.

[R ₂ Si (OH) O _1/2 ] _a [R ₂ Si
O _2/2 ] _b [RSi (OH) O _2/2 ] _c [RSi
O _3/2 ] _d

Here, R is independently one or more monovalent hydrocarbon groups, and examples thereof include an alkyl group such as a methyl group and an ethyl group, and an aromatic hydrocarbon group such as an alkenyl group and a phenyl group. , Preferably a methyl group.
a, b, c and d satisfy the following conditions. (1) a + b + c + d = 1 (where a is 0 or a positive number and b, c, and d are positive numbers) (2) 0.001 ≦ (a + b) / (c + d) ≦ 1.0;
And (3) 0.12 ≦ c / (c + d) ≦ 0.35. Here, the value of (a + b) / (c + d) represents the ratio of the bifunctional unit (diorganosiloxy unit) in the curable silicone resin of the present invention. If this value is below the lower limit of the range of the above (2), a polyorganosilsesquioxane essentially having no bifunctional unit (diorganosiloxy unit) will result. On the other hand, if the unit exceeds the upper limit of the range (2), the flexibility component becomes too large, and the shape becomes almost rubbery. Note that (a + b) / (c
+ D) is from 0.03 to from the viewpoint of the properties of the cured product.
A range of 1.0 is recommended. The value of c / (c + d), that is, the molar amount of silanol to 1 mol of silicon in the monoorganosiloxy unit (polyorganosilsesquioxane structure) is in the range of 0.12 to 0.35. If the amount of the silanol is less than this, the curability may decrease, or the resin may be inferior in physical heat stability of the cured product as shown in Comparative Examples. If the amount of silanol is larger than this, the storage stability of the resin may be reduced. There is no particular limitation on the molecular weight of the curable silicone resin of the present invention. Usually, those having a weight average molecular weight of 500 to 100,000 and / or a number average molecular weight of 200 to 200,000 are selected, but are not limited thereto.

[0012] The curable silicone resin of the present invention comprises a unit having a substituent other than the set substituent R or a monofunctional (R ₃ Si
O _1/2 ), and may contain some tetrafunctional (SiO _4/2 ) units. The silicone resin contains silanol, and its structure is as shown in the above structural formula, but there may be a unit having a silanol group in a structure other than this at a trace level. . Although the silicone resin of the present invention has the above structure, structural units generated due to such causes and the like,
As long as the characteristic properties of the silicone resin are not impaired, its presence is not denied.

The curable silicone resin of the present invention is prepared by the following two-phase reaction system comprising the following (a) and (b):
It is produced by subjecting (B) to hydrolysis and condensation. (A) an oxygen-containing organic solvent, or an organic solvent obtained by mixing 50 parts by volume or less of a hydrocarbon solvent with the solvent; (b) 1.8 moles per mole of a halogen atom in the following (A) and (B) Water containing or not containing a gram equivalent or less of a water-soluble inorganic base or a salt of a weak acid having a buffering ability. (A) Formula RSix ₃ (R has the same meaning as described above, and X is a halogen atom.) Organotrihalosilane, (B) Formula Y (SiR ₂ O) _e SiR ₂ Y (Y is one or more selected from a halogen atom, a hydroxyl group, and hydrogen; e is a positive integer of 0 or 300 or less; The same meaning), or a diorganopolysiloxane having functional groups at both ends.
When Y is a halogen atom, Cl is preferably selected.

Preferred examples of such a production method include the following. (1) A two-phase reaction system consisting of the above (a) and (b) is formed, and a mixture of the above (A) and (B) or a solution in which (A) and (B) are dissolved in the above (a) To conduct the reaction by dropping. (2) A solution obtained by dissolving the above (A) and (B) in the above (a) is dropped into the above aqueous phase (b).
A method of performing a reaction in a phase reaction system. (3) A method in which a solution obtained by dissolving the above (A) and (B) in the above (a) and the above (b) are simultaneously dropped into a reaction vessel, and the resulting mixture is reacted in a two-phase reaction system. (4) A two-phase reaction system of (a) and (b) in which (B) in which Y is at least one selected from a hydroxyl group and hydrogen is formed, and (A) or (a) A method in which a reaction in which A) is dissolved is performed dropwise. Alternatively, only (A) may be hydrolyzed by the methods (1), (2), and (3), and then (B) may be dropped and reacted.

The reaction temperature is suitably in the range of room temperature (20.degree. C.) to 120.degree. C., preferably about 40 to 100.degree.

The fact that water and the organic solvent form two phases means that water and the organic solvent are not mixed and a uniform solution is not obtained. The organic phase and the aqueous phase may be present in such a manner that the two phases form an upper layer and a lower layer by lowering the stirring speed, and a state of having a wide flat interface between them is maintained. May be expressed as "forming two layers"), and the two layers may not be maintained by vigorous stirring. However, from a practical point of view, the latter which does not require careful control of the stirring speed is preferred.

When X of the halosilane (A) and Y of the starting material (B) are a halogen atom, Y is preferably bromine, chlorine, and more preferably chlorine. E in (B) is a positive number of 0 or 300 or less, that is, a difunctional diorganosilane or a diorganopolysiloxane having a functional group at both terminals. When it is a diorganopolysiloxane, it may have a molecular weight distribution, a branched structure, a cyclic compound, or a side chain functional group in a range produced in an industrial production method or the like.

The organic solvent used in this production method may dissolve (A) and (B) and may be slightly dissolved in water, but an oxygen-containing organic solvent capable of forming two phases with water is used. Note that a mixed solvent of an oxygen-containing organic solvent and a hydrocarbon solvent is used in place of the oxygen-containing organic solvent (however, the volume ratio is 50 parts by volume or less of the hydrocarbon solvent in 100 parts by volume of the mixed solvent). Can also. If the content of the hydrocarbon solvent is higher than this, the amount of gel formed increases, the yield of the target product decreases, and it may not be practical. Alternatively, when the content of the hydrocarbon solvent is large, the desired physical properties of the cured product may not be obtained. As the organic solvent, a solvent that is insoluble in water indefinitely and that is immiscible with an aqueous solution of a water-soluble inorganic base or a salt of a weak acid having a buffer ability can be used.

Examples of the oxygen-containing organic solvent include ketone solvents such as methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, acetylacetone and cyclohexanone, ether solvents such as diethyl ether, dinormal propyl ether, dioxane, diethylene glycol dimethyl ether, tetrahydrofuran, and ethyl acetate. Butyl acetate, butyl propionate and the like; and ester solvents such as n-butanol and hexanol, but are not limited thereto. But,
In order to obtain the desired physical thermal stability of the cured product, it is preferable that the cured product is not an alcohol solvent. These solvents may be used as a mixture of two or more kinds. Examples of the hydrocarbon solvent include aromatic hydrocarbon solvents such as benzene, toluene, and xylene; aliphatic hydrocarbon solvents such as hexane and heptane; chloroform, trichloroethylene, and halogenated hydrocarbon solvents such as carbon tetrachloride. It is not limited to these. The amount of the organic solvent used is not particularly limited, but is preferably in the range of 50 to 2,000 parts by weight based on 100 parts by weight of the total of (A) and (B). If the amount of the organic solvent is less than 50 parts by weight based on 100 parts by weight of the total of (A) and (B), it is insufficient to dissolve the formed silicone resin, and may cause gelation in some cases. If the amount exceeds the above range, hydrolysis and condensation do not proceed rapidly, and a silicone resin having a low molecular weight and poor storage stability is obtained. The amount of water used is not particularly limited, but preferably 10 to 10 parts by weight of the total amount of (A) and (B).
It is in the range of 3000 parts by weight.

The aqueous phase may contain a water-soluble inorganic base or a salt of a weak acid having a buffering ability for suppressing acidity due to hydrogen halide generated from halosilane, but the reaction is not effected even with water without any addition. It is possible.

Examples of the water-soluble inorganic base include water-soluble alkalis such as lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, and magnesium hydroxide. Carbonates such as sodium, potassium carbonate, calcium carbonate and magnesium carbonate; hydrogen carbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate; oxalates such as potassium bis (oxalate) trihydrogen; potassium hydrogen phthalate; sodium acetate; But phosphates such as disodium hydrogen phosphate and potassium dihydrogen phosphate, borates such as sodium tetraborate, and the like, but are not limited thereto. Further, these amounts are desirably not more than 1.8 gram equivalents to 1 mol of the total halogen atoms of the halogen in the halosilane molecule used and when Y in (B) is a halogen. That is, the amount is desirably 1.8 times or less the amount that just neutralizes the hydrogen halide generated when the halosilane is completely hydrolyzed. These water-soluble inorganic bases or salts of weak acids having a buffering ability may be used as a mixture of two or more kinds within the above-mentioned quantitative range.

The curing of the silicone resin of the present invention is carried out by heating or using a catalyst or a crosslinking agent. The curing reaction may be carried out by melting the silicone resin as it is, or by casting a solution of an organic solvent and heating after evaporating the solvent.

Solvents for dissolving the silicone resin of the present invention include aromatic hydrocarbon solvents such as benzene, toluene and xylene, ether solvents such as diethyl ether and tetrahydrofuran, alcohol solvents such as butanol and hexanol, acetone and methyl ethyl ketone. And ketone solvents such as methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, and halogenated hydrocarbon solvents such as chloroform, trichloroethylene and carbon tetrachloride.

The curable silicone resin thus produced can be cured by heating or using a curing catalyst and / or a crosslinking agent. The curing temperature is 20 ° C. or higher when a curing catalyst and / or a crosslinking agent is used.
The temperature is 50 ° C or lower, preferably 20 ° C or higher and 250 ° C or lower.
If the temperature is lower than 20 ° C., the reaction does not proceed sufficiently. If the temperature is higher than 350 ° C., siloxane may be decomposed. In the case of curing only by heating, the temperature is from 50 ° C to 350 ° C, preferably from 80 ° C to 250 ° C. 50 ℃
If it is less than 10, the reaction does not proceed sufficiently. If it exceeds 350 ° C., siloxane may be decomposed.

Examples of the curing catalyst include tin diacetate, tin dioctylate, tin dilaurate, tin tetraacetate, dibutyl tin diacetate, dibutyl tin dioctylate, dibutyl tin dilaurate, dibutyl tin dioleate, dimethoxy dibutyl tin,
Tin compounds such as dibutyltin oxide, dibutyltin benzylmaleate, bis (triethoxysiloxy) dibutyltin, diphenyltin diacetate; tetramethoxytitanium;
Tetraethoxytitanium, tetra-n-propoxytitanium, tetra-i-propoxytitanium, tetra-n-butoxytitanium, tetra-i-butoxytitanium, tetrakis (2-ethylhexoxy) titanium, di-i-propoxybis (ethylacetoacetate) ) Titanium, titanium dipropoxybis (acetylacetonate) titanium, di-i-
Propoxybis (acetylacetonato) titanium, dibutoxybis (acetylacetonato) titanium, tri-i
Titanium compounds such as propoxyallyl acetate titanium, titanium isopropoxyoctylene glycol, bis (acetylacetonato) titanium oxide; lead diacetate, lead bis (2-ethylhexanoate), lead dineodecanoate, lead tetraacetate, tetrakis ( Lead n-propionate), zinc diacetate, zinc bis (2-ethylhexanoate), zinc dionedecanoate, zinc diundecenoate, zinc dimethacrylate, iron diacetate, zirconium tetrakis (2-ethylhexanoate), tetrakis ( Metal fatty acids such as zirconium (methacrylic acid) and cobalt diacetate; aminopropyltrimethoxysilane, N- (2-aminoethyl) -3
-Aminopropyltrimethoxysilane, tetramethylguanidine, tetramethylguanidylpropyltrimethoxysilane, tetramethylguanidylpropyldimethoxysilane, tetramethylguanidylpropyltris (trimethylsiloxane) silane, 1,8-diazabicyclo [5 .4.0. And an amino group-containing compound such as -7-undecene. Usually, it is used in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of polymethylsilsesquioxane.

Examples of the crosslinking agent include the following compounds.

[0027]

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[0028]

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The crosslinking agent is usually used in an amount of 0.1 to 80 parts by weight, preferably 1 to 70 parts by weight, based on 100 parts by weight of the silicone resin.
Used in parts by weight.

[0030]

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 160 mL of water and 120 mL of methyl isobutyl ketone were added to a reaction vessel equipped with a reflux condenser, a dropping funnel, and a stirrer, stirred vigorously so as not to form two layers, and placed in an ice bath. Was. When the temperature of the mixture in the reaction vessel reached 15 ° C., a solution in which 51.6 g (0.345 mol) of methyltrichlorosilane and 7.85 g (0.0608 mol) of dimethyldichlorosilane were dissolved in 40 mL of methyl isobutyl ketone Was slowly dropped from the dropping funnel. At this time, the temperature of the reaction mixture rose to 28 ° C. After completion of the dropwise addition, the reaction mixture was added to an oil bath at 60 ° C. for 2 hours.
The mixture was heated and stirred for hours. After the completion of the reaction, the organic layer was washed until the washing water became neutral, and then the organic layer was dried using a desiccant. After removing the desiccant, the solvent was distilled off under reduced pressure, followed by vacuum drying for two days and night to obtain a silicone resin as a white solid. The molecular weight distribution of this silicone resin was determined by GPC.
[Manufactured by Tosoh Corporation HLC-8020, column using Tosoh Corporation TSKgelGMH _XL -L + G1000H _XL (TM), toluene was used as the solvent] was measured by the weight-average molecular weight of the standard polystyrene equivalent 4
830 and the number average molecular weight was 1230. Also
The molar ratio of diorganosiloxy units to monoorganosiloxy units determined from the ²⁹ Si NMR spectrum (measured by Bruker ACP-300), that is, (a + b) / (c
+ D) is 0.21, silicon 1 in a monoorganosiloxy unit (polyorganosilsesquioxane structure)
The molar amount of silanol to the mole, ie, c / (c +
The value of d) was 0.180. The molar amount of silanol relative to 1 mol of silicon in the diorganosiloxy unit, that is, the value of a / (a + b) was 0.058. This silicone resin did not change in molecular weight distribution and solubility even when left in air at room temperature for 6 months.

1 g of this silicone resin was dissolved in 5 g of chloroform, and 5 mg of tin dioctylate was added thereto.
The obtained solution was applied on a glass plate and left at room temperature for 2 hours. The formed transparent film was peeled off from the glass plate, cut into the size of a test piece, and heat-crosslinked at 100 ° C for 1 hour and at 200 ° C for 2 hours. Table 1 shows the shear modulus at a test frequency of 1 Hz measured on the film obtained in accordance with JIS K6394 for three points of temperature. The shear modulus was only gradually reduced, and the hardness was maintained even at a high temperature of 200 ° C. or higher.

(Example 2) The same reaction apparatus as in Example 1
Under the conditions, water 400mL and methyl isobutyl ketone 300mL
Was stirred, and 106.4 g (0.71 g) of methyltrichlorosilane dissolved in 100 mL of methyl isobutyl ketone was dissolved.
2 mol) and 11.8 g of polydimethylsiloxane having hydroxyl groups at both ends and having an average degree of polymerization of 4 was added dropwise. The reaction mixture was heated and stirred for 2 hours on a 55 ° C. oil bath,
The same treatment as in Example 1 was performed to obtain a silicone resin as a wax-like solid. (A +) determined from the ²⁹ Si NMR spectrum of the silicone resin thus obtained.
The value of b) / (c + d) was 0.18, and the value of c / (c + d) was 0.262. The value of a / (a + b) was 0. This silicone resin did not change in molecular weight distribution and solubility even when left in air at room temperature for 6 months.

This silicone resin was cured in the same manner as in Example 1. Table 1 shows the shear modulus of the cured film at a test frequency of 1 Hz. Even when the length of the diorganosiloxy unit was increased, there was no transition in which the elastic modulus suddenly decreased, and the hardness was maintained even at a high temperature.

(Example 3) In the same manner as in Example 2, the reaction was carried out using a polydimethylsiloxane having a hydroxyl group at both terminals having a degree of polymerization of 13 to obtain a silicone resin as a wax-like solid. (A + b) / (c) determined from the ²⁹ Si NMR spectrum of the obtained silicone resin
+ D) is 0.17, and the value of c / (c + d) is 0.25.
Nine. The value of a / (a + b) was 0. This silicone resin did not change in molecular weight distribution and solubility even when left in air at room temperature for 6 months.

This silicone resin was cured in the same manner as in Example 1. Table 1 shows the shear modulus of the cured film at a test frequency of 1 Hz. Even when the diorganosiloxy unit was further lengthened, the transition in which the elastic modulus decreased sharply was not observed, and the hardness was maintained even at a high temperature.

Example 4 In the same manner as in Example 2, the reaction was carried out using polydimethylsiloxane having a hydroxyl group at both terminals and having a degree of polymerization of 55 to obtain a silicone resin as a wax-like solid. The weight average molecular weight of the obtained silicone resin in terms of polystyrene determined by GPC was 6,260, and the number average molecular weight was 850. (A + b) / determined from ²⁹ Si NMR spectrum
The value of (c + d) is 0.17, and the value of c / (c + d) is 0.1.
259. The value of a / (a + b) was 0. This silicone resin did not change in molecular weight distribution and solubility even when left in air at room temperature for 6 months.

This silicone resin was cured in the same manner as in Example 1. Table 1 shows the shear modulus of the cured film at a test frequency of 1 Hz. Even when the diorganosiloxy unit was further lengthened, the transition in which the elastic modulus decreased sharply was not observed, and the hardness was maintained even at a high temperature.

Example 5 In the same manner as in Example 1, 41.7 g (0.279 mol) of methyltrichlorosilane and 15.6 g (0.121 mol) of dimethyldichlorosilane were used on an oil bath at 60 ° C. For 1 hour to obtain a silicone resin as a highly viscous liquid. The weight average molecular weight of the obtained silicone resin in terms of standard polystyrene determined by GPC was 1,300, and the number average molecular weight was 520.
Met. (A +) determined from the ²⁹ Si NMR spectrum.
The value of b) / (c + d) was 0.43, the value of c / (c + d) was 0.238, and the value of a / (a + b) was 0.059. This silicone resin did not change in molecular weight distribution and solubility even when left in air at room temperature for 6 months.

This silicone resin was cured in the same manner as in Example 1. Table 1 shows the shear modulus of the cured film at a test frequency of 1 Hz. Even when the amount of diorganosiloxy units was increased, the transition in which the elastic modulus was sharply decreased was not observed, and the hardness was maintained even at a high temperature.

(Example 6) In the same manner as in Example 2, polydimethylsiloxane having a hydroxyl group at both ends was used with a polymerization degree of 12, and methyltrichlorosilane was used.
4 g (0.712 mol) was reacted with 34 g of polydimethylsiloxane having hydroxyl groups at both ends and having an average degree of polymerization of 12 to obtain a silicone resin as a highly viscous liquid. ²⁹ S
(a + b) / (c + d) determined from iNMR spectrum
Was 0.56 and the value of c / (c + d) was 0.280. The value of a / (a + b) was 0. This silicone resin did not change in molecular weight distribution and solubility even when left in air at room temperature for 6 months.

This silicone resin was cured in the same manner as in Example 1. Table 1 shows the shear modulus of the cured film at a test frequency of 1 Hz. Even when the amount of diorganosiloxy unit was polysiloxane and the amount was further increased, no sudden decrease in the elastic modulus was observed, and the hardness was maintained even at a high temperature.

Comparative Example 1 As in Example 1, 50.5 g (0.338 mol) of methyltrichlorosilane and 8.06 g (0.0624 mol) of dimethyldichlorosilane were used, but methyl isobutyl ketone was used as an organic solvent. Was carried out using toluene and isopropyl alcohol instead of. That is, these chlorosilanes were dissolved in 40 mL of toluene, and added dropwise to a two-phase reaction system of 160 mL of water, 90 mL of toluene, and 30 mL of isopropyl alcohol. The silicone resin obtained by performing the same treatment as in Example 1
Despite having the same composition as in Example 1, it was a high-viscosity liquid. The weight average molecular weight in terms of standard polystyrene determined by GPC was 12,100, and the number average molecular weight was 1,870. The value of (a + b) / (c + d) determined from the ²⁹ Si NMR spectrum was 0.18, and a / (a +
The value of b) was 0.064, but the value of c / (c + d) was as low as 0.064. In the ¹ H NMR spectrum, the presence of a 2-propoxy group was observed, and ²⁹ SiNM
About 40% of the amount of silanol determined from the R spectrum is 2-
It could be estimated to be propoxy.

This silicone resin was cured in the same manner as in Example 1. Table 1 shows the shear modulus of the cured film at a test frequency of 1 Hz. Despite the starting materials and amounts being the same as in Example 1, the elastic modulus shows a sharp drop of more than two orders of magnitude in the region from 50 ° C. to 100 ° C.,
Hardness at high temperature could not be maintained.

[Table 1] Temperature Dependence of Shear Modulus (MPa) of Silicone Resin Cured Film Example No. 25 ° C. 100 ° C. 200 ° C. ───────── Example 1 490 210 125 Example 2 450 190 180 Example 3 420 160 100 Example 4 400 240 230 Example 5 230 85 70 Example 6 140 80 80 Comparative Example 1 380 1 .5 1────────────────────────────

[0046]

The present invention provides a method for producing a curable silicone resin which is indispensable for producing a cured silicone resin having excellent properties. The cured product of the silicone resin obtained by the present invention has excellent physical thermal stability, that is, the elastic modulus does not decrease even at a high temperature. Therefore, in addition to the general properties of silicone resins, such as thermal stability (high thermal decomposition onset temperature), electrical insulation, and flame resistance, they are widely used for applications requiring higher hardness at high temperatures. Application becomes possible.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihito Saito 1324-1 Shushuyusawa, Gotemba-shi, Shizuoka Prefecture (72) Teruhito Maruyama 1-17-7 Higashi-Otake, Isehara-shi, Kanagawa Prefecture No.205 Segile Asuka 205

Claims (8)

[Claims] An average structure represented by the general formula [R ₂ Si (OH) O _1/2 ] _a [R ₂ SiO _2/2 ]
_b [RSi (OH) O _2/2 ] _c [RSiO _3/2 ] _d [R is each independently a monovalent hydrocarbon group;
b, c and d satisfy the following conditions. (1) a + b + c + d = 1 (where a is 0 or a positive number and b, c, and d are positive numbers) (2) 0.001 ≦ (a + b) / (c + d) ≦ 1.0 ( 3) 0.12 ≦ c / (c + d) ≦ 0.35] A curable silicone resin represented by the following formula (A) and (B) is used in a two-phase reaction system comprising the following (a) and (b): By subjecting the compound to hydrolysis and condensation. (A) the next or oxygen-containing organic solvent A mixed solvent comprising an oxygen-containing organic solvent and a hydrocarbon solvent (provided that the volume ratio is 50 parts by volume or less in 100 parts by volume of the mixed solvent), (B) relative to 1 mole of halogen atoms in the following compounds (A) and (B):
1.8 g or less of a water-soluble inorganic base or water with or without a salt of a weak acid having a buffering capacity, (A) Formula RSix ₃ (R has the same meaning as described above, and X is a halogen atom. (B) Formula Y (SiR ₂ O) _e SiR ₂ Y (Y is one or more selected from a halogen atom, a hydroxyl group, and hydrogen, and e is a positive number of 0 or 300 or less; R has the same meaning as described above), or a diorganopolysiloxane having a functional group at both ends. 2. The method for producing a curable silicone resin according to claim 1, wherein said R is a methyl group. 3. A two-phase reaction system of (a) and (b) is formed, and (A) and (B) are dissolved in a mixture of (A) and (B) or in (a). The method for producing a curable silicone resin according to claim 1 or 2, wherein the reaction is performed by dropping the solution. 4. A method in which a solution obtained by dissolving the components (A) and (B) in the component (a) is dropped into the aqueous phase of component (b), and the resulting mixture is reacted in a two-phase reaction system. The method for producing a curable silicone resin according to claim 1 or 2, wherein: 5. A solution obtained by dissolving the components (A) and (B) in the component (a) and the component (b) are simultaneously dropped into a reaction vessel, and the resulting mixture is reacted in a two-phase reaction system. The method for producing a curable silicone resin according to claim 1, wherein: 6. A two-phase reaction system of (a) and (b) in which (B) in which Y is at least one selected from a hydroxyl group and hydrogen is formed, and the above-mentioned (A) or (a) is formed. ) To (A)
The method for producing a curable silicone resin according to claim 1 or 2, wherein the reaction is carried out by dropping a solution in which is dissolved. 7. An organic phase and an aqueous phase do not keep two layers by vigorously stirring the reaction system, that is, a state where these two phases form an upper layer and a lower layer and have a wide flat interface therebetween. The method for producing a curable silicone resin according to any one of claims 1 to 6, wherein the reaction is carried out so as not to cause the reaction. 8. A catalyst prepared by heating the curable silicone resin produced by the method according to claim 1 at a temperature of 50 ° C. or more and 350 ° C. or less, or at a temperature of 20 ° C. or more and 350 ° C. or less. Alternatively, a method for producing a cured silicone resin using a crosslinking agent.