JP2599517B2 - Method for producing organopolysiloxane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an organopolysiloxane, and more particularly, to a method of using an alkoxysilane or a partial hydrolyzate thereof alone or as a mixture to form a gel by controlling a hydrolysis reaction. Without alcohol to get out of the system
The present invention relates to a method for producing an organopolysiloxane which can be easily treated for wastewater.

[0002]

2. Description of the Prior Art Methods for producing organopolysiloxanes by hydrolyzing organochlorosilanes have been widely used in the silicone industry. However, in this method, since the hydrolysis reaction is fast and difficult to control, it is difficult to adjust the molecular weight distribution of the organopolysiloxane, and a gel is generated. Therefore, it is necessary to add a large amount of alcohol in order to stabilize the reaction system and make it easy to control, but since a large amount of alcohol to be added is discharged into wastewater generated in a subsequent washing step, There is a disadvantage that the purification treatment of the wastewater becomes large. Furthermore, this method requires a treatment because hydrochloric acid is by-produced. This hydrochloric acid has a strong pungent odor and is harmful to the human body.
Since the piping and other incidental equipment are significantly corroded, there is also a problem that the apparatus is made of an expensive corrosion-resistant material, and a large number of people and costs are required for repair and the like.

As a method for producing an organopolysiloxane, a method is known in which an alkoxysilane is produced by hydrolysis. For example, a method of co-hydrolyzing an alkoxysilane in the presence of a basic catalyst (JP-A-56-15)
No. 1731, JP-A-59-66422) and a method of hydrolysis in the presence of an acid catalyst (JP-A-59-683).
No. 77 gazette) is known. These methods have the advantage that the hydrolysis reaction is easier to control than the hydrolysis from chlorosilane, and hydrochloric acid is not produced as a by-product. But,
Since a large amount of alcohol is generated in the reaction system and is contained in and discharged from the wastewater in a water washing step for removing the catalyst, there is a disadvantage that the load on the wastewater treatment equipment increases. Another method is to hydrolyze an alkoxysilane with a stoichiometric excess of water in the presence of a solid acid catalyst, and then strip off the by-produced alcohol (Japanese Patent Laid-Open No. 58-108227).
However, when the raw material contains a large amount of trifunctional silane, hydrolysis is carried out by adding a stoichiometrically excess amount of hydrolyzed water and the alcohol is hydrolyzed in the presence of a catalyst. When distilling off, there is a problem that the condensation reaction cannot be controlled and gels.

As described above, the method of hydrolyzing alkoxysilane has an advantage compared to the hydrolysis of chlorosilane. However, in the method which has been known so far, a large amount of wastewater treatment equipment is required for treating alcohol in wastewater. There is a problem in that a burden is imposed or gelation occurs when the by-product alcohol is distilled off in the presence of a catalyst, that is, before the washing step.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention relates to a method for producing an organopolysiloxane using an alkoxysilane or a partial hydrolyzate thereof alone or as a mixture. The purpose of the present invention is to provide a novel method which does not cause gelation and facilitates wastewater treatment.

[0006]

The present invention SUMMARY OF] is obtained by solving the above problems, the general formula _{R a Si (OR) 4-} a ( here, R represents the same or different monovalent hydrocarbon radical, a Is 0,
In conducting the hydrolysis reaction of the organoalkoxysilane represented by 1, 2, or 3) or a partial hydrolyzate thereof alone or in the presence of an organic solvent and an acid catalyst, a. The hydrolysis water is used in a molar ratio of 25 to 4 with respect to the alkoxy group.
After 5% addition and hydrolysis, b. Distilling off by-product alcohol in the system under reduced pressure or normal pressure; c. A method for producing an organopolysiloxane, comprising adding the remaining water to complete the hydrolysis reaction so that the total amount of hydrolysis water added is 60 to 180% by mole relative to the alkoxy group. ,
It is the gist. That is, the present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that a desired product can be obtained by distilling off by-product alcohol without gelling the organopolysiloxane under the above-described conditions, and As a result, the present inventors have found that the amount of alcohol in the wastewater can be drastically reduced, thereby facilitating the wastewater treatment.

Hereinafter, the present invention will be described in detail. Organoalkoxysilanes or a partial hydrolyzate thereof for use in the method of the present invention have the general formula R _a Si (OR)
_4-a is an organoalkoxysilane represented by (a is 0, 1, 2, or 3) or a partial hydrolyzate thereof. R in the formula may be the same or different, and may be an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group, a cycloalkyl group such as a cyclohexyl group, an alkenyl group such as a vinyl group or an allyl group, or a phenyl group. Represents a monovalent hydrocarbon group selected from aryl groups and the like. The partial hydrolyzate is a siloxane oligomer of the above alkoxysilane, and is mainly a dimer to a 15-mer alone or as a mixture.

The acid catalyst used in the method of the present invention is not particularly limited as long as it is an acid. For example, hydrochloric acid, sulfuric acid, sulfonic acid, nitric acid, acetic acid and the like can be mentioned. The organic solvent used in the method of the present invention is not particularly limited as long as it dissolves the starting alkoxysilanes and does not adversely affect the reaction, and examples thereof include ketones such as methyl ethyl ketone and dimethyl ketone, toluene, and xylene.

In the method of the present invention, first, an organoalkoxysilane or a partial hydrolyzate thereof or a mixture thereof together with an organic solvent and an acid catalyst is charged into a reaction vessel, and water is gradually added with stirring to cause a hydrolysis reaction. As described above, the amount of water added is 25 to
45%. Although it is possible to proceed the process without gelation even if it is less than 25%, the distillation amount in the alcohol distillation step is less than 50% of the theoretical amount, so that a large effect cannot be expected, and the burden on the wastewater purification treatment equipment is heavy. 45%
If it exceeds, polymerization proceeds in the alcohol distillation step,
A gel is likely to be generated in a later step. The amount of the organic solvent used may be 40 to 60 parts by weight with respect to 100 parts by weight of the total amount of silane and its partial hydrolyzate, and the amount of the acid catalyst may be 0.1 to 1.0 part by weight Good. The reaction temperature may usually be about 15-60 ° C.

When the above-mentioned hydrolysis reaction is completed, the by-produced alcohol is distilled off under reduced pressure or normal pressure by a conventional method. In the case where the organic solvent is entrained during the distillation and the distillation is reduced, the organic solvent may be added during or after the distillation, if necessary. Next, the remaining water is added so that the total amount of the added water is 60 to 180% in molar ratio with respect to the alkoxy group, and the hydrolysis reaction and the polymerization reaction are performed. If the amount of water is less than 60%, a large amount of unreacted alkoxy groups bonded to silicon atoms in the siloxane remain, and if it exceeds 180%, the concentration of the catalyst becomes low. The alkoxy group remains, which affects the product. The reaction temperature is usually about 30 to 60 ° C. Stirring may be performed to complete the reaction.

When the predetermined hydrolysis reaction and polymerization reaction are completed, the catalyst is removed by a method such as washing with water. At the time of washing, sodium sulfate may be dissolved in the washing water in order to improve the separation between the aqueous layer and the organic solvent / siloxane layer.
After that, if necessary, evaporation or dehydration of organic solvent, filtration,
Density adjustment or the like may be performed. The alcohol separated by distillation can be subjected to a treatment such as incineration or, if necessary, regenerated and reused.

As described above, according to the present invention, the by-produced alcohol is distilled off and separated, so that the amount of the alcohol transferred to the washing water is remarkably reduced, so that the wastewater treatment becomes extremely easy. Moreover, no gel of organopolysiloxane is generated. The organopolysiloxane produced by the method of the present invention has excellent heat resistance and electrical properties, and can be suitably used for insulation treatment, protective sealing, moisture-proof surface treatment, mica molded products, etc. in the electric and electronic industries. In addition, it has excellent weather resistance and can be used for various paints.

[0013]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to the following examples. Example 1 1 equipped with a thermometer, a stirrer, a condenser, and a dropping funnel
339.2 g of methyltrimethoxysilane, 315 g of toluene, 4-propanol 4
After 5.8 g and 4.6 g of methanesulfonic acid were added and mixed, 55.0 g of water (39.9 mol% based on methoxy group) was added dropwise at room temperature with stirring for 20 minutes to hydrolyze. Then, the temperature inside the tank was raised, and volatile components were distilled off over about 4 hours until the temperature reached 78 ° C. The distillation component at that time is methanol 18
6.5 g, toluene 88.3 g, 2-propanol 1
The amount was 4.8 g, and 78% of the theoretical amount of by-produced methanol could be distilled off. Next, 145.0 g of toluene was added, and 55.0 g of water (39.9 mol% with respect to methoxy group, total amount of 79.8 mol%) was again added dropwise at room temperature with stirring for 20 minutes. Was heated to 50 ° C. and polymerized for 90 minutes.
Then, in order to remove the catalyst and stop the polymerization, washing was performed until the washing liquid became neutral. After further dehydration and filtration, the siloxane concentration was adjusted to 50% by weight. No gel was generated in this series of steps. The molecular weight of the organopolysiloxane in the obtained solution was 2,950 as the number average molecular weight in terms of polystyrene.

Example 2 1 equipped with a thermometer, a stirrer, a condenser and a dropping funnel
In a liter four-necked flask, the average formula (CH ₃ ) SiO _0.592 (OC
H ₃ ) 300 g of a partial hydrolyzate of methyltrimethoxysilane represented by _1.82 , 350 g of toluene, 45.1 g of 2-propanol, 6.87 of a 70% aqueous methanesulfonic acid solution
g of water and mixed.
(0.0 mol%) was added dropwise over 11 minutes with stirring at room temperature to effect hydrolysis. Then, the temperature inside the tank was raised, and volatile components were distilled off until the temperature reached 80 ° C. over about 70 minutes. The components distilled off at that time were 105.8 g of methanol, 106.5 g of toluene,
It was 24.7 g of 2-propanol, and 66% of the theoretical amount of by-product methanol could be distilled off. Next, 250.0 g of toluene was added, and 54.1 g of water (60.0 mol% based on methoxy groups, a total amount of 100 mol%) was added again dropwise at room temperature with stirring for 11 minutes. 90 ° C
Polymerized for minutes. Then, in order to remove the catalyst and stop the polymerization, washing was performed until the washing liquid became neutral. After further dehydration and filtration, all the solvent was distilled off. No gel was generated in this series of steps. The molecular weight of the obtained organopolysiloxane was 10,400 in terms of polystyrene equivalent number average molecular weight, and the softening point was 61.6 ° C.

Comparative Example 1 A 1 equipped with a thermometer, a stirrer, a condensing cooler, and a dropping funnel
Average formula (CH ₃ ) _1.09 SiO _0.54 (O
CH ₃ ) Partial hydrolyzate of methoxysilane represented by _1.93 2
13.8 g of a 35% hydrochloric acid aqueous solution was added dropwise to 48 g with stirring at room temperature for 10 minutes to cause a reaction. Then stir for 20 minutes,
82.7 g of water and 124 g of toluene were added. Next, the temperature in the tank was raised to 40 ° C., and polymerization was carried out for 60 minutes. Then, 99 g of a 10% aqueous sodium sulfate solution was added to stop the polymerization. To remove hydrochloric acid, water washing was performed with a 10% aqueous solution of sodium sulfate until the washing liquid became neutral. After further dehydration and filtration,
The siloxane concentration was adjusted to 50% by weight. The molecular weight of the organopolysiloxane in the obtained solution was 30,20 as the number average molecular weight in terms of polystyrene. Most of the methanol by-produced during the reaction was contained in the wastewater in the washing step and discarded.

Comparative Example 2 1 equipped with a thermometer, a stirrer, a condenser, and a dropping funnel
In a liter four-necked flask, the average formula (CH ₃ ) SiO _0.665 (OC
H ₃ ) After mixing 300 g of the partially hydrolyzed product of methyltrimethoxysilane represented by _1.67 , 300 g of toluene, 14.7 g of 2-propanol and 2.4 g of methanesulfonic acid, 52.8 g of water (based on methoxy group 61) was added. 0.7 mol%)
Was added dropwise over 20 minutes with stirring at room temperature to cause a reaction. Thereafter, at a temperature in the tank of 30 ° C. and a pressure of 120 mmHg, 95
For 9 minutes, 92.7 g of toluene and 81.7 g of methanol were distilled off. Then, after adding 100 g of toluene, washing was performed with water to remove the catalyst and terminate the polymerization, but a gel was generated.

[0017]

According to the novel method of the present invention, a desired organopolysiloxane is obtained by using an alkoxysilane or a partial hydrolyzate thereof alone or as a mixture without forming a gel and reducing the amount of alcohol discharged in wastewater. Polysiloxanes can be produced. Therefore, the effect of the present invention is great.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kazushi Sato Shin-Etsu Chemical Co., Ltd. 2-6-1 Otemachi, Chiyoda-ku, Tokyo

Claims (1)

(57) [Claims] 1. A general formula _{R a Si (OR) 4-} a ( here, R
Are the same or different monovalent hydrocarbon groups, and a is a hydrolysis reaction of an organoalkoxysilane represented by 0, 1, 2, or 3) alone or in the form of a mixture or a mixture thereof in the presence of an organic solvent and an acid catalyst. In doing so, a. The hydrolysis water is used in a molar ratio of 25 to 4 with respect to the alkoxy group.
After 5% addition and hydrolysis, b. Distilling off by-product alcohol in the system under reduced pressure or normal pressure; c. A method for producing an organopolysiloxane, comprising adding the remaining water to complete the hydrolysis reaction so that the total amount of hydrolysis water added is 60 to 180% by mole relative to the alkoxy group. .