JP2001354770A - Polymethylsilsesquioxane and process for producing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a highly polymerized polymethylsilsesquioxane which is soluble in various solvents, is excellent in storage stability, and can be suitably used as a film for preventing a stain and marring of various articles and as a semiconductor material. SOLUTION: The process for producing the polymethylsilsesquioxane comprises (I) a step of hydrolyzing an organosilane represented by CH3Si(OR2)3 (wherein R2 is a 1-3C alkyl) in a solvent mixture comprising water containing an acid in an amount of 0.0001-0.1 mmol/g and an alcohol represented by R1OH (wherein R1 is a 1-4C alkyl), (II) a step of bringing the hydrolyzed organosilane obtained in the step (I) into contact with an organic solvent and a strong acid which will separate into two layers after contact with the hydrolyzate, thus allowing the hydrolyzate to condense, and (III) a step of polymerizing in an alkaline atmosphere the condensation product obtained in the step (II).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to polymethylsilsesquioxane using methyltrialkoxysilane as a raw material and a method for producing the same, and particularly to a polymer which is soluble in various solvents and has storage stability. And a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Silicone polymers can take many forms depending on their constituent units. One of the well-known forms is resin, which is a polymer with RSiO _3/2 as the main unit, and when cured, a material with high hardness and high elastic modulus can be obtained. Used as a film forming material. These resins are low molecular weight polymers having a hydrolyzable group or a hydroxyl group at the terminal, and upon curing, these terminal groups condense to form a hard film. However, when a low molecular weight silicone resin is used, water and alcohol are generated by condensation of the terminal groups, and the condensation proceeds excessively to form a film that is too hard, so that cracks are easily generated. In order to improve this drawback, a method of increasing the molecular weight to reduce the hydrolyzable group or the hydroxyl group, which is a curable group, can be considered. However, it is difficult to control the intermolecular condensation reaction in the process of increasing the molecular weight by a usual method, and as a result, gelation is caused. Therefore, various methods for avoiding such gelation have been proposed.

As a method for obtaining polymethylsilsesquioxane (hereinafter sometimes referred to as PMSQ) by hydrolyzing methyltrichlorosilane, a method using ketone and ether as a solvent in the presence of an amine (JP-A-53-1983) 8809
No. 9) and a method in which hydrolysis is carried out in the presence of an alkali metal carboxylate (Japanese Patent Application Laid-Open No. 3-227321). It has the drawback that it is difficult to handle, for example, it easily undergoes hydrolysis and generates corrosive gas, hydrogen chloride.

As a method using methyltrialkoxysilane as a raw material, a method for producing PMSQ powder by alkali hydrolysis has been proposed (JP-A-63-77940). This powder is a particulate gel insoluble in a solvent. ,
It is not suitable for a film forming material. A method for producing a solution of PMSQ in a mixed solvent of hydrochloric acid and ethanol as a film forming material (J. Polym, Sei., Part A. Poly)
m. Chem. 1995, 33, 751), but this PMSQ is a partial hydrolyzate and has a problem of low storage stability.

JP-A-2-36234 discloses that a silicone resin composition serving as a silicone pressure-sensitive adhesive is hydrolyzed by adding an acid to several types of silanes having different numbers of hydrolyzable groups and different substituents to form an acid catalyst. Polycondensation in the presence, it is described that can be produced by polycondensation in the presence of an alkali catalyst, but there is no specific disclosure, the structure of the resin is greatly different, the resin has a high molecular weight It is not something to make it.

The present invention has been made in view of the above circumstances, and in particular, polymethylsilsesquioxane which is soluble in various solvents and has excellent storage stability while being a polymer, and a method for producing the same. The purpose is to provide.

[0007]

Means for Solving the Problems and Embodiments of the Invention In order to achieve the above object, the present inventors have proposed a method for producing PMSQ using methyltrialkoxysilane as a raw material. Excellent PMSQ
As a result of studying a method for producing the compound, methyltrialkoxysilane was hydrolyzed in a solvent consisting of water and an alcohol containing a specific ratio of an acid, and then the hydrolyzate was condensed with a strong acid as a catalyst, and then further subjected to alkali polymerization , A highly polymerizable soluble PMSQ with excellent storage stability
Have been obtained, and the present invention has been completed.

That is, the present invention relates to (I) water containing an acid of 0.001 to 0.1 mmol / g and an alcohol represented by R ¹ OH (R ¹ represents an alkyl group having 1 to 4 carbon atoms). CH ₃ Si (OR ² ) in a mixed solvent of
Step (II) of hydrolyzing an organosilane represented by ₃ (R ² is an alkyl group having 1 to 3 carbon atoms) (II) Then, the hydrolyzate of the organosilane obtained in the step (I) is A step of contacting an organic solvent which separates into two layers after contact and a strong acid to condense the hydrolyzate (III) and a step of polymerizing the main condensate obtained in step (II) in an alkaline atmosphere A method for producing polymethylsilsesquioxane is provided. The present invention also provides a weight-average molecular weight of 1000, which is obtained by the above method and is converted into standard polystyrene by gel permeation chromatography.
Provided is polymethylsilsesquioxane that is soluble in an organic solvent in which a portion occupied by 0 or more is present in 50% or more.

Hereinafter, the present invention will be described in more detail.
The method for producing polymethylsilsesquioxane of the present invention includes three steps: (I) a hydrolysis step, (II) a condensation step, and (III) a polymerization step.

( I) Hydrolysis Step In the step (I), (a) water and (b) R ¹ OH are used as raw materials.
Alcohol represented by (R ¹ is an alkyl group having 1 to 4 carbon atoms), (c) acid, (d) CH ₃ Si (OR ² ) ₃ (R ² is an alkyl group having 1 to 3 carbon atoms) Using organosilane, organosilane (d) in a mixed solvent (hydrolysis solvent) of water (a) containing acid (c) and alcohol (b)
Is hydrolyzed.

Here, (a) water is not particularly limited, but (c) ion-exchanged water is preferable because it does not contain impurities that inhibit the catalytic action of acid. (B)
R ¹ OH is a lower alcohol having 1 to 4 carbon atoms,
Specific examples include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, s-butanol and t-butanol, which may be used alone or as a mixture of two or more. Although the ratio of (a) water and (b) R ¹ OH is not particularly limited, (a) /
(B) = 10 / 90-90 / 10, especially 25 / 75-7
It is preferably 5/25 (weight ratio). (A) If the amount of water is less than this, gelation is likely to occur in step (II), and the yield of PMSQ will be low. (B) If the amount of R ¹ OH is less than this, ( d) C
Since the solubility of H ₃ Si (OR ² ) ₃ is low, a uniform solution of the hydrolyzate cannot be obtained, and a gel is easily formed in the step (I), which may lower the yield of PMSQ. The type of the acid (c) is not particularly limited as long as it has hydrolytic ability, and specific examples thereof include inorganic acids such as sulfuric acid, nitric acid, hydrogen chloride, and phosphoric acid, and organic acids such as carboxylic acid. (C) The amount of the acid is an amount at which the hydrolysis reaction proceeds, and the amount is 0.0001 to 0.1 mmol / g in the mixed solvent of (a) and (b), preferably 0.001 to 0.1 mmol / g. 0.01mmo
1 / g. If the amount is less than 0.0001 mmol / g, gelation in the step (II) tends to occur, and if the amount is more than 0.1 mmol / g, gelation in the step (I) is likely to occur.
Q becomes difficult to obtain. Although the mechanism of gelation is not clear, when the acid concentration is low, a partially hydrolyzed monomer having SiOH and SiOR is generated, and this SiOH and S
It is considered that gelation occurs in step (II) due to the difference in the condensation rate of iOR. On the other hand, when the acid concentration is high, the silanol generated by the hydrolysis causes a condensation reaction to generate a polyfunctional oligomer, which forms an irregular crosslink in the condensation reaction in the next step, thereby generating a gel. It is thought that there is not.

(D) CH ₃ Si (OR ² ) ₃ is a methyltrialkoxysilane in which R ² is an alkyl group having 1 to 3 carbon atoms, specifically, methyltrimethoxysilane,
Methyltriethoxysilane, methyltripropoxysilane and the like can be mentioned, but methyltrimethoxysilane is preferred from the viewpoint of easy hydrolysis and availability. (D) CH
The hydrolyzate of ₃ Si (OR ² ) ₃ is (d) CH ₃ Si (O
R ² ) ₃ is preferably contacted at a ratio of 0.1 mmol to 2 mmol with respect to 1 g of the hydrolysis solvent composed of (a), (b) and (c), more preferably 0.5 mmol to 2 mmol.
The range is 1 mmol. If it is less than 0.1 mmol, the productivity is too low, and if it is more than 2 mmol, gelation is likely to occur in step (II), and it may be difficult to obtain PMSQ efficiently.

Next, regarding the hydrolysis method, first, a hydrolysis solvent comprising (a), (b) and (c) is prepared, and (d) is brought into contact with the solvent to effect hydrolysis. It is preferable that the hydrolyzate of (d) and the sum of (d) with respect to the hydrolysis solvent be contacted at a concentration not exceeding 2 mmol / g at any time of the hydrolysis at 2 mmol / g.
If it exceeds, a gel is likely to be formed. The device to be brought into contact is not limited, but specific examples include a batch-type stirring reaction tank and a flow mixer. The reaction temperature is not particularly limited. Specifically, in the case of methyltrimethoxysilane, 25
Although the reaction is carried out at a temperature of ° C., the hydrolysis may be carried out between the boiling point of the mixed reaction solvent and a temperature at which the mixed reaction solvent does not condense in order to adjust the hydrolysis rate. The hydrolysis time is usually several seconds to 1 hour.

( II) Condensation Step In the step (II), an organic solvent (e) which separates into two layers after contacting the organosilane hydrolyzate obtained in the above step (I) with this hydrolyzate, and a strong acid (f) ) To condense the hydrolyzate.

Here, (e) is not particularly limited as long as it is an organic solvent which separates into two layers after contact, and specifically, aromatic solvents such as benzene, toluene, xylene, hexane, and the like.
Saturated hydrocarbon solvents such as heptane, octane, nonane, and decane are exemplified. (F) is not particularly limited as long as it is a strong acid capable of condensing the hydrolyzate of methyltrialkoxysilane obtained in step (I), and specific examples thereof include sulfuric acid, nitric acid, hydrogen chloride methanesulfonic acid, and trifluoromethane. An organic acid such as methanesulfonic acid is mentioned, and sulfuric acid, which is a nonvolatile and strong acid, is particularly preferable.

(E) The amount of the organic solvent is
Any amount can be used as long as it can dissolve and maintain a liquid state, but the weight ratio to the hydrolyzate of (d) is preferably 0.1 to 10. If it is less than 0.1, the concentration of the hydrolyzed condensate in the organic solvent layer is too high to form a viscous solution, which makes handling difficult, and gelation easily occurs in step (III). If more than 10 is added, the process (I
The concentration of PMSQ in the solution obtained after II) becomes extremely dilute, and a separate step of distilling a large amount of solvent may be required when forming or casting PMSQ. (F) The amount of the strong acid may be an amount capable of condensing the hydrolyzate obtained in step (I), but is preferably 0.1 to 1 in terms of a weight ratio to the hydrolyzate of (d).
0, more preferably 0.5 to 5. If it is less than 0.1, the condensation is slow, and gelation easily occurs in the step (III). This is presumably because many SiOH groups and SiOR groups remain. Also, even if it is added more than 10, there is no significant difference in the physical properties and characteristics of the obtained PMSQ. p
H is preferably 3 or less, particularly preferably 2 or less.

Next, regarding the condensation method, the order of contact is as follows: (e) an organic solvent is added to the hydrolyzate of methyltrialkoxysilane and then (f) a strong acid is contacted, or the hydrolysis of methyltrialkoxysilane is performed. Preferably, (e) and (f) are brought into contact with the product at the same time, but this dissolves the hydrolysis condensate of methyltrialkoxysilane generated by the condensation reaction due to the presence of (e) in the reaction system, This is because a liquid state that can be stirred can be maintained. The device to be brought into contact is not limited, but specific examples include a batch-type stirring reaction tank and a flow mixer. The condensation reaction temperature is preferably from room temperature to the boiling point of the organic solvent, and the reaction time is usually from 1 minute to 10 hours.

( III) Polymerization Step Step (III) is a step of polymerizing the main condensation product obtained in the above step (II) in an alkaline atmosphere.

In order to make the atmosphere alkaline, an alkali may be added. (G) The alkali is added in the above step (II).
Although there is no particular limitation as long as it has the ability to further condense the hydrolyzed condensate of methyltrialkoxysilane obtained in the above, specifically, alkali metal hydroxides such as LiOH, NaOH, KOH, Ca (OH) ₂ , Examples thereof include alkaline earth metal hydroxides such as Mg (OH) ₂ , amines, and NH ₃ , and the amount is not particularly limited as long as the inside of the reaction system becomes alkaline. The pH may be more than 7, preferably 8 or more, particularly preferably 10 or more.

Next, the method of condensation will be described. The solution obtained in step (II) is a two-phase system containing an organic solvent phase containing PMSQ and an acid. Although good, it is preferable to (g) wash the organic solvent phase containing PMSQ after separating the layer containing acid in order to minimize the amount of alkali, and add (g) alkali. In addition,
The reaction temperature is preferably from room temperature to the boiling point of the organic solvent, and the reaction time is usually from 1 minute to 10 hours.

According to the present invention, the portion occupied by the weight average molecular weight of 10,000 or more in terms of standard polystyrene by gel permeation chromatography is 50 or more.
%, Especially 60% or more of the above-mentioned (e) organic solvent-soluble PMSQ resin can be obtained. Also,
(E) The organic solvent can be removed and solidified. The obtained solid can be solidified with (e) an organic solvent and a solvent other than (e), such as ketones, ethers, esters, and alcohols. It is also possible to redissolve. The obtained solution has good storage stability and does not lose solvent solubility for a long time even when it is in a solid state. Further, ²⁹ by _{Si-NMR CH 3 SiO 3/2 (} = T3) CH 3 Si with respect to the unit
(OR) ₂ O _1/2 (= T1) unit and CH ₃ Si (OR) O
A PMSQ having a structure with a high degree of condensation, in which the ratio of the sum of _2/2 (= T2) units is 0.25 or less, can be obtained.

[0022]

According to the present invention, it is possible to obtain polymethylsilsesquioxane which is a polymer, is soluble in various solvents, and has excellent stability. The soluble polymethylsilsesquioxane can be suitably used as a film for preventing dirt and abrasion of various articles and a material for semiconductors.

[0023]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The terms used in the following examples will be described below. -Weight average molecular weight The weight average molecular weight is a value in terms of styrene calculated by a Tosoh GPC apparatus. ^-29 Si-NMR analysis The structural unit ratio of the silicone resin is a value measured by ²⁹ Si-NMR. -Solid content The solid content is the remaining amount after heating in a PMSQ solution at 105 ° C for 3 hours in a circulating oven. -Yield The structure of PMSQ in the solution was calculated from the solid content as (MeSiO3 _{/ 2} ) _n . -Storage stability The PMSQ solution is stored in a borosilicate glass bottle at room temperature for 3 months, and the gel is visually checked by filtration with a filter paper.

Example 1 1900 g of ion-exchanged water, 1900 g of methanol and 1 g of sulfuric acid were placed in a 10 L three-necked flask.
At 25 ° C. under stirring at 25 ° C.
0 g was added to obtain a hydrolyzate solution. To this, 1000 g of toluene and 1000 g of sulfuric acid were added with stirring (pH 1).
Heat at 0 ° C. for 2 hours. After cooling and standing at room temperature, the lower layer was separated after standing, and the upper layer was washed three times with 1,000 g of ion-exchanged water to obtain a toluene solution of a hydrolyzate of methyltrimethoxysilane. 1% NaOH aqueous solution 2
After adding 0 g (pH 11) and reacting at 86 ° C. for 3 hours, washing with 200 g of ion-exchanged water was performed 5 times, followed by filtration with filter paper to obtain 976 g of a PMSQ solution.

The solid content of the obtained solution was 11.1%, the yield was 55%, and the weight average molecular weight of the solid content was 3960.
00, weight average molecular weight in GPC area ratio is 1000
0% or more is 71%, T1 / T by ²⁹ Si-NMR
The 2 / T3 ratio was 0.0 / 15.7 / 84.3.

The resulting solution was stored at room temperature for 3 months and filtered through a filter paper, but no gel was found. Further, PMSQ resin obtained by removing the solvent under reduced pressure can be used in toluene and PGM even after storage at room temperature for 3 months.
It was soluble in EA and no gel formation was observed.

When the obtained PMSQ solution was applied to a steel plate and air-dried, a uniform film was formed. 200 ℃
For 1 hour, no cracks were observed in the film.

[Examples 2 to 9] Synthesis was carried out in the same manner as in Example 1 with the formulations shown in Tables 1 and 2 to obtain a PMSQ solution.

Comparative Example 1 In a 10 L three-necked flask, 1900 g of ion-exchanged water, 1900 g of methanol, and 0.1 ml of sulfuric acid were added.
01 g was added, and 400 g of methyltrimethoxysilane was added at 25 ° C. with stirring to obtain a hydrolyzate solution. Under stirring, 1000 g of toluene and 1000 g of sulfuric acid were added thereto.
, The whole inside of the reaction tank became a soft gel in 30 minutes. This is considered to be due to partial hydrolysis of the product in Step I and heterogeneous condensation in Step II. This did not give PMSQ.

Comparative Example 2 1900 g of ion-exchanged water, 1900 g of methanol, 20 sulfuric acid were placed in a 10 L three-necked flask.
When 0 g was added and 400 g of methyltrimethoxysilane was added at 25 ° C. with stirring, a large amount of solid gel was formed. It is considered that this is because the hydrolyzate was sequentially condensed by high-concentration sulfuric acid and polymerized. This allows PM
SQ was not obtained.

Comparative Example 3 3800 g of ion-exchanged water and 1 g of sulfuric acid were added to a 10 L three-necked flask, and 400 g of methyltrimethoxysilane was added at 25 ° C. with stirring. did. When the stirring was further continued, a large amount of white solid gel was formed. This did not give a PMSQ solution.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J035 BA12 BA14 CA01K CA06U CA061 EB02 LA03 LB01 4J038 DL031 LA02 MA14 NA05 NA11 NA26

Claims (5)

[Claims] (I) 0.0001 to 0.1 mmol /
g containing water and R ¹OH (R¹Is an alk having 1 to 4 carbon atoms
In a mixed solvent with an alcohol represented by
H_ThreeSi (OR^Two)_Three(R^TwoIs an alkyl group having 1 to 3 carbon atoms)
A step of hydrolyzing an organosilane represented by
(II) Next, the organosilane obtained in the step (I)
Separate into two layers after contact with this hydrolyzate
The hydrolyzate is condensed by contacting an organic solvent with a strong acid.
(III) then obtained in step (II)
Including a step of polymerizing the main condensation product in an alkaline atmosphere
Of polymethylsilsesquioxane characterized by
Construction method. 2. In the step (I), CH ₃ Si (O
R ² ) ₃ is prepared by converting an organosilane represented by ₃ into water containing an acid and R ^1.
0.1 g per 1 g of a mixed solvent with an alcohol represented by OH.
2. The method according to claim 1, wherein the hydrolysis is carried out by contacting at a ratio of 1 to 2 mmol. 3. In the step (II), a weight ratio of the organosilane hydrolyzate, the organic solvent and the strong acid is 1: 0.1.
The method according to claim 1, wherein the contact is performed at a ratio of 10 to 0.1: 0.1 to 10. 4. A weight average molecular weight obtained by the production method according to claim 1, which is obtained by gel permeation chromatography and converted into standard polystyrene, is 1000.
A polymethylsilsesquioxane soluble in an organic solvent in which a portion occupied by 0 or more exists in 50% or more. 5. CH_ThreeSiO_3/2C for (T3) units
H_ThreeSi (OR)_TwoO _1/2(T1) Unit and CH_ThreeSi (O
R) O_2/2(T2) The ratio of the sum of the units is 0.25 or less
5. The organic solvent-soluble polymer according to claim 4,
Limethylsilsesquioxane.