HU201342B - Process for producing polysiloxanes - Google Patents

Abstract

During the prepn. of substd. polysiloxanes linear substd. siloxane oligomer or oligomers contg. silanol end gps. react in the presence of alkyl-, alkenyl-, and/or aryl-silyl-perchlorate catalyst. Following this the reaction mix is neutralised by an inorganic or organic base.

Description

This invention relates to an average molecular weight linear dimethyl sziloxivagy optionally substituted with from ⁷ 105 to 10 with respect substituted dimethylsiloxane units, 0.1 to 10 mol% of vinyl siloxy, dimethylsiloxane-based polymers, silanol end groups 10 ³ - Starting from an average molecular weight of 10 ⁴ dimethylsiloxane, by acid catalyzed polycondensation and neutralization of the reaction mixture.

A number of processes are known for preparing organic silicon polymers. Part of the known processes is based on organic alpha, omega-oligosiloxane diols, which are polycondensed in the presence of various catalysts, using perchloric acid or a mixture of perchloric acid and low-carbon organic acid (1-5C) according to Hungarian Patent Application No. 193,873. 40-80 ° C) and low catalyst concentration allows ^(_a 10 -1 wt%) preparation of 10 ³ -10 ⁷ average molecular weight organopolysiloxane mixtures.

A disadvantage of the known process is the relatively long reaction time.

The aim of the invention having to provide an economically feasible method 10 ⁵ -10 average molecular weight linear dimethyl siloxane and / or siloxy units, based on the dimethyl 0.1-10 mole% methyl-vinyl siloxy-substituted sealed or reactive end-groups ^of between ⁷ , dimethylsiloxane-based polymers with a short reaction time.

It has been found that the above object is achieved by carrying out the polycondensation in the presence of 10 ^{5 to} 10% by weight of the catalyst based on dimethylsiloxane oligomer at 40-120 ° C and atmospheric pressure and as the catalyst trimethylsilyl perchlorate, a mixture of at least one of vinylsilyl perchlorate and methyl vinylsilyl diperchlorate and a 0.1 to 10 molar mixture of C 1 -C 4 organic carboxylic acid or carboxylic anhydride or C 1 -C 4 alcohol.

The present invention is based on the discovery that when anhydrous alkyl or alkenyl perchlorate is used instead of perchloric acid, the rate of polycondensation is greatly increased because the catalyst system used in the invention provides, in one step, the incorporation of hetero units into the chain and the insertion of chain terminating units. Thus, it is no longer necessary to prepare the raw materials which fulfill these functions and to react them in a polycondensation reaction.

The oligomer of the silanol end groups used as starting materials in the process of the invention having an average molecular weight of 3,10 to 10 ⁴ dimethylpolysiloxane is prepared by directed hydrolysis of dimethyldichlorosilane (Noll, W .: Chemie und Technologie d Silicone, Verlag Chemie GmbH, Weinheim). 1968, p. 169].

The organic silyl perchlorates used as catalysts are characterized by the following general formula:

R11Sil OC1O3) 4 where R = CH3, C2H5 or

CH2 = CH and n = 2, 3 (Wannagat, U .: Z. anorg.alig.Chem., 302, 185 (1959).)

The catalyst is used in an amount of 105 to 10%, preferably 0.01 to 1% by weight based on the weight of the starting dimethylsiloxane oligomer.

In the process according to the invention, the polycondensation is carried out intermittently at a temperature of 40-120 ° C, preferably 40-80 ° C. Once the desired average molecular weight is reached, the catalyst is neutralized with an inorganic or organic base in a manner known per se. Preferably the inorganic base is ammonia gas or an inorganic ammonium salt such as ammonium carbonate. Organic bases include primary, secondary, tertiary, or quaternary amines. Triethylamine is preferably used.

The advantages of the process according to the invention can be summarized as follows:

1 can be prepared from the high molecular weight organopolysiloxanes (M = 10 ⁵ -10 ⁷⁾ short reaction time.

2. When using a catalyst system containing dimethyl or methyl vinyl diperclorate silane, the hetero units are integrated into the chain in one step.

3. If a catalyst system containing trimethyl or dimethyl vinylsilyl perchlorate is used, the addition of blocking units shall be ensured in addition to maintaining the catalytic polycondensation.

The invention is illustrated in detail by the following examples.

Example 1

In a 200 ml flask fitted with a stirrer and a condenser, 1 mole of trimethylsilyl perchlorate in a 100 g solution having a viscosity of 50-160 mPa.s and an average molecular weight M = 3-10 ³ -10 ⁴ hydroxyl-terminated linear dimethylpolysiloxane (LMS). of methanol solution was added. The reaction mixture was heated to 60 ° C and stirred at this temperature for 1 hour. After the reaction time, the catalyst was neutralized with 0.2 g of ammonium carbonate. Excess ammonium carbonate is removed by heating to 100 ° C.

After a reaction time of 1 h, the average molecular weight of the polymer terminated with trimethylsilyl terminated is M = 250,000.

Comparative Example (Reproduction of the process according to Hungarian Patent Specification No. 193,873)

HU 201342 Β

For 100 g of a viscosity of 50-160 mPa.s, an average molecular weight of M = 3-10 ³ -10 ⁴ , hydroxy-terminated linear diraethyl polysiloxane (LMS), 0.2 g of hexamethyldisiloxane as catalyst, 10 g of 70% perchloric acid as catalyst and 0.1 ml of a mixture of 90 g of acetic anhydride are added. The reaction was carried out at 60 ° C for 8 hours. The average molecular weight of the trimethylsiloxy-terminated polymerizer is M = 200,000.

Comparison of Example 1 and Comparative Example shows that the known process requires eight times the reaction time to achieve an average molecular weight of M = 200,000 than that of the process of the present invention to obtain an average molecular weight of M = 250,000.

EXAMPLE 2 1 M Methyl Vinylsilyl Dipchlorate in a 3,000 g laboratory with a stirrer having a viscosity of 50 to 160 Pa.s, having an average molecular weight of M = 3-10 ³ -10 ⁴ , hydroxyl-terminated dimethyl polysiloxane (LMS). of methanol solution (20 ml). The reaction mixture was stirred at 60 ° C for 6 hours. After the reaction time, the catalyst was neutralized with 2.5 g of powdered ammonium carbonate.

The average molecular weight of the polymerate containing 0.05 mol X methyl vinyl siloxy groups is M = 2.6-10 ⁶ .

Example 3

For the 3000 grams of the apparatus described in Example 2, 15 g of methyl vinyl polysiloxane hydrolyzate and 1 molar trimethylsilyl perchlorate in methanol were added to 3000 g of a viscosity of 50-160 mPa.s with an average viscosity of Μ = 3-0 ³ -10 ^4. 1 ml was added. The reaction was carried out at 60 ° C for 6 hours. After the reaction time, the catalyst was neutralized with ammonium carbonate.

The average molecular weight of the trimethylsilyl-terminated polymer containing 0.4 mol X of methyl vinyl siloxy groups is csoport ^, β-ΙΟ ⁶ .

Example 4

With a 200 ml stirrer, in a flask fitted with a condenser, having a viscosity of 100 g, 50 to 160 mPa.s,

Ml = 6 ml of a linear solution of oC, w-dimethylpolysiloxane diol having an average molecular weight of ^{3 to} 0 ^{3 to} 10 ^{4 in} acetic anhydride solution of 1 M methyl vinyl dipercloroethane silane and 1 ml acetic anhydride solution of dimethyl vinyl perchlorate silane. We are added. The reaction mixture was heated to 50 ° C and stirred at this temperature for 4 hours. After the reaction time, the catalyst was neutralized as described in Example 1. The average molecular weight of the polymer containing 0.5 mol X methyl vinylsiloxy units in the chain closed with the dimethyl vinyl siloxy unit is M = 350,000.

Example 5

The procedure described in Example 1 was followed except that 1 ml of a 1 molar solution of trimethylsilyl perchlorate in acetic acid was used as the catalyst and the reaction mixture was stirred for 30 minutes at 120 ° C.

The trimethylsilyl group has a closed end polymer 20 having an average molecular weight of M = 250,000-260,000.

Claims (5)

PATENT CLAIMS A process for the preparation of dimethylsiloxane-based polymers having an average molecular weight of 10 ^{5 to} 10 ⁷ , based on linear dimethylsiloxy or optionally substituted with 0.1 to 10 moles of vinylsiloxy on linear units of dimethylsiloxy, containing silanol end groups. Starting from an average molecular weight of 10 ⁴ dimethylsiloxane, acid catalyzed polycondensation and neutralization of the reaction mixture, characterized in that the polycondensation is carried out in the presence of 10 ^{5 to} 10% by weight of dimethylsiloxane oligomer at 40-120 ° C and atmospheric pressure. and as a catalyst a 0.1-10 molar mixture of at least one of trimethylsilyl perchlorate, dimethyl vinylsilyl perchlorate and methyl vinylsilyl diperclorate, and a C 1 -C 4 organic carboxylic acid or carboxylic anhydride or C 1 -C 4 alcohol. used. 2. The process of claim 1 wherein the catalyst is present in an amount of 0.01 to 1% by weight. The process according to claim 1 or 2, wherein the catalyst is a mixture of trimethylsilyl perchlorate and methanol. The process according to claim 1 or 2, wherein the catalyst is a mixture of methyl vinylsilyl diperclorate, dimethyl vinylsilyl perchlorate and acetic anhydride. Process according to claim 1 or 2, characterized in that the catalyst is a mixture of trimethylsilyl perchlorate and acetic acid. Published by the National Office for Inventions, Budapest Responsible: Dr. Gabriella Szvoboda Head of Department