JP2824950B2 - Method for producing high molecular weight 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 a high molecular weight organopolysiloxane by dehydration condensation of an organopolysiloxane having a Si--OH group.

[0002]

2. Description of the Related Art A method of extending the chain length of a hydroxy group-containing organopolysiloxane using various silane compounds has been proposed.
Conventionally known.

For example, US Pat. No. 3,776,934 discloses that methylvinylbis (N-methylacetamido) silane is reacted with an organopolysiloxane having both ends capped with a hydroxy group to cure at room temperature. A method for producing a silicone elastomer composition of the present invention is disclosed.

Japanese Patent Publication No. 55-49623 discloses a method of mixing a hydroxy group-containing organosiloxane with methylvinylbis (ε-caprolactamo) silane to obtain a hydroxy group-containing organosiloxane having an increased molecular weight.

Japanese Patent Publication No. 61-12932 discloses that a hydroxy group-containing organosiloxane having an increased molecular weight is obtained by mixing a hydroxy group-containing organosiloxane, a cyclosiloxane having two vinyloxy groups bonded thereto, and a guanidine derivative. A method is disclosed.

[0006] However, in the above prior art method,
There is a problem that an amide or caprolactam with toxicity or odor is produced as a by-product or a cyclosiloxane that is difficult to synthesize is used, and these are not necessarily highly practical.

As a method for solving the above-mentioned problems, Japanese Patent Laid-Open Publication No. Hei 3-179027 discloses a method in which a hydroxy group-containing organosiloxane and an acidic compound having a pKa of 3 or less are mixed to obtain a polymer having a high molecular weight. Methods for obtaining organopolysiloxanes have been proposed.

[Problems to be solved by the invention]

Certainly, the above-mentioned method using an acidic compound does not cause problems such as toxicity and the problem that a compound which is difficult to synthesize must be used. However,
After obtaining a high molecular weight organopolysiloxane, it may be necessary to remove the acidic compound or neutralize the acidic compound with a basic compound. However, the obtained organopolysiloxane is 100,000 cP (centipoise).
When it has the above high viscosity, it is difficult to remove the acidic compound due to the high viscosity, and it is also difficult to perform the neutralization smoothly. For example, a special kneading device such as a kneader is required. There is a problem. Further, there is a problem that siloxane bonds in the obtained polysiloxane are cleaved due to the presence of an acidic compound or a basic compound, and siloxane units are randomly rearranged.

On the other hand, Japanese Patent Publication No. 38-350 discloses a hydroxy group (Si-OH group) bonded to a silicon atom using a salt of a hydrocarbon carboxylic acid or phosphoric acid and an amino compound as a catalyst. To obtain a high molecular weight organopolysiloxane by condensing the compound. According to this method, it is possible to carry out the condensation reaction without breaking the siloxane bond. However, since the condensation rate is low, there is a fatal drawback that the method lacks practicality.

Accordingly, an object of the present invention is to provide a high-molecular-weight organopolysiloxane which can rapidly undergo a dehydration-condensation reaction between organopolysiloxanes having a Si—OH group without breaking or rearranging siloxane bonds. It is to provide a method capable of manufacturing a.

[0011]

According to the present invention, Si-
In a method for producing a high molecular weight organopolysiloxane by a dehydration condensation reaction of an organosiloxane having at least one OH group in one molecule, at least one fluorine atom is bonded to a carbon atom at the α-position of a carboxyl group as a reaction catalyst. And a salt of a carboxylic acid and a basic amino compound having a hydrogen atom and / or a carbon atom bonded to all of the bonds of the nitrogen atom.
There is provided a method for producing a high molecular weight organopolysiloxane, wherein the method is used in an amount of 0.001 to 10 parts by weight per 0 parts by weight and the dehydration condensation reaction is carried out in the presence of the salt.

[0012]

The method of the present invention is basically based on the following reaction formula: ~ Si-OH + HO-Si ~ >>> ~ Si-O
The dehydration condensation reaction represented by -Si~ + H ₂ O, is to produce the organopolysiloxane high molecular weight by extending the chain length of the organosiloxane. Such a method utilizing the dehydration condensation reaction of the Si-OH group does not use a compound having toxicity or odor and does not produce such a compound as a by-product. It has the advantage that it does not need to be used as a raw material, and is extremely practical as a method for producing a high molecular weight organopolysiloxane.

A particularly important feature of the present invention is that a salt of a carboxylic acid having at least one fluorine atom bonded to the carbon atom at the α-position of a carboxyl group with a basic amino compound is used as a reaction catalyst. It is. Thereby, the above-mentioned dehydration condensation reaction proceeds rapidly. In addition, since the presence of the salt does not cause the cleavage of the siloxane bond, there is no need to remove or neutralize the salt after the completion of the reaction, which is industrially extremely advantageous.

[0014]

In Si-OH group-containing organosiloxane present invention a preferred embodiment of the invention, as starting material, the organosiloxane is used having at least one Si-OH groups in one molecule. That is, this organosiloxane is composed of Si-
The structure is not particularly limited as long as the dehydration condensation reaction described above is effectively performed by having an OH group,
For example, it may be in the form of a homopolymer or a copolymer, or a mixture of these polymers. The structural unit of the organosiloxane may be composed of a monoorganosiloxane unit, a diorganosiloxane unit, a triorganosiloxy unit, or a combination of these units.

The group bonded to the silicon atom other than the hydroxyl group is generally an unsubstituted or substituted monovalent hydrocarbon group. Examples of the unsubstituted monovalent hydrocarbon group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a hexyl group and an octadecyl group, a cycloalkyl group such as a cyclohexyl group, a vinyl group, an allyl group, a cyclohexyl group, and a cyclohexenyl group. Alkenyl group such as group, aryl group such as phenyl group and tolyl group, and aralkyl group such as benzyl group and phenylethyl group. Examples of the substituted monovalent hydrocarbon group include a group in which a hydrogen atom of the above group is substituted with a halogen atom or a cyano group, for example, a chloromethyl group,
Halogenated hydrocarbon groups such as chloropropyl group, 3,3,3-trifluoropropyl group, α, α, α-trifluorotolyl group, chlorobenzyl group and bromopropyl group; cyano groups such as cyanoethyl group and cyanopropyl group; Hydrocarbon groups can be mentioned. In the present invention, particularly preferred are a methyl group, a vinyl group, a phenyl group, and a 3,3,3-trifluoropropyl group.

In the above-mentioned organosiloxane containing a Si-OH group, the Si-OH group is preferably present at the terminal of the molecular chain in order to promptly promote the dehydration condensation reaction. Is preferably present.

Reaction Catalyst In the present invention, the carboxylic acid used to form the salt as a reaction catalyst must be one having at least one fluorine atom bonded to the carbon atom at the α-position of the carboxyl group. No. For example, as shown in Comparative Examples described below, when a salt formed using a normal hydrocarbon carboxylic acid having no fluorine atom at such a position is used as a reaction catalyst, The dehydration-condensation reaction between the Si-OH groups of the organosiloxane described above does not proceed rapidly, and it takes a long time to achieve a high molecular weight of the organosiloxane, which impairs practicality.

Representative examples of such a carboxylic acid having a fluorine atom at the carbon atom at the α-position include, but are not limited to, the following. CF ₃ COOH, CH ₂ FCOOH, C ₈ F ₁₇ COO
H, C ₃ F ₇ OCF ₂ CF ₂ COOH, HOOC (CF
_{2) 4 COOH, C 3 F} 7 O-Y-COOH _{[Y: -CF (CF 3) CF} 2 O (CF 3) CF- ],
_{C 4 H 9 CF 2 CF 2} COOH, CH 3 O- (CH 2)
_{3 -O- (CH 2) 3 -CF} 2 CF 2 COOH

The basic amino compound is a compound in which a hydrogen atom and / or a carbon atom is bonded to all the bonds of a nitrogen atom, and any basic compound can be used as long as it can form a salt with the above-mentioned fluorine-containing carboxylic acid. Things can be used. Suitable examples thereof include ammonia, primary amine, secondary amine and tertiary amine. Of course, those containing two or more amino groups in one molecule can also be used. Can be. Specifically, although not limited thereto, ammonia, methylamine, dimethylamine, triethylamine, octylamine, piperidine,
Examples thereof include N-methylarsolamine, aniline, para-bromoaniline, decylamine, 2-aminopyridine and the like.

The above-mentioned salt of a fluorinated carboxylic acid and an amino compound is a salt of an organosiloxane containing a Si—OH group.
0.001 to 10 parts by weight, preferably 0.1 to 10 parts by weight per 0 parts by weight
Used in a proportion of 2.0 parts by weight. If the amount is less than 0.001 part by weight, the dehydration condensation reaction hardly proceeds, and if it is used in an amount greater than 10 parts by weight, no further effect is exhibited, and it is economically disadvantageous.

The salts used as reaction catalysts include liquid salts and solid salts. In particular, since the solid form has poor dispersibility as it is, it can be used by dissolving it in an organic solvent as necessary. Examples of the organic solvent used in this case include alcohol solvents such as methanol, ethanol, and isopropanol; ether solvents such as diethyl ether, dioxane, and tetrahydrofuran; ketone solvents such as acetone and methyl ethyl ketone; and ester solvents such as ethyl acetate. And hydrocarbon solvents such as toluene, xylene and n-hexane, and chlorine solvents such as chloroform and trichloroethane. These organic solvents are used alone or as a mixture of two or more.

Dehydration-condensation reaction In the present invention, the dehydration-condensation reaction between the Si-OH group-containing organosiloxane is carried out by reacting a mixture of the organosiloxane and the above-mentioned salt at 20 to 180 ° C, particularly 60 to 150 ° C.
Heating or heating and holding quickly progresses. If this temperature is lower than 20 ° C., the reaction rate may be slow and practicality may be impaired. Setting the temperature higher than 180 ° C. wastes energy and has no economic merit. By setting the reaction time in a range from several hours to one day, the desired high molecular weight organopolysiloxane can be obtained. The reaction may be carried out without using a solvent, or, if necessary, using an organic solvent inert to the reaction.

Generally, organopolysiloxanes are liable to undergo a siloxane cleavage reaction by an acid or a base. Especially 10
At a temperature higher than 0 ° C., a weak acid such as acetic acid or a weak base such as an amine also causes a siloxane cleavage reaction to form a low-molecular siloxane. However, in the case of the salt used as a reaction catalyst in the present invention, siloxane bond hardly breaks even at a high temperature up to 200 ° C., and a high molecular weight organopolysiloxane can be obtained stably. Therefore, in the present invention, it is not necessary to remove the above-mentioned salt after completion of the reaction, which is industrially extremely advantageous.

The high molecular weight organopolysiloxane obtained by the method of the present invention is used in various fields. In particular, when applied to construction-related fields such as gaskets, the salt used as a reaction catalyst acts as a surfactant. Therefore, there are additional advantages such as prevention of contamination by silicone.

[0025]

EXAMPLES In the following specific examples, the viscosity is a value measured at a temperature of 25 ° C. Examples 1 to 4 and Comparative Example 1 In a 200 ml separable flask equipped with a stirring rod, dimethylpolysiloxane having both ends blocked with hydroxyl groups (viscosity: 7
20cP) 100.0 g and 0.3 g of a salt of a carboxylic acid and an amino compound shown in Table 1 or Table 2 were added and mixed, and reacted while stirring at 120 ° C.
It thickened with time. Tables 1 and 2 show the viscosity of the reaction system measured at each time.

[0026]

[Table 1]

[0027]

[Table 2]

Examples 5-7 In a 200 ml separable flask equipped with a stir bar,
Is added to 100.0 g of a diorganopolysiloxane in which both terminals are blocked with a hydroxyl group as shown in the following formula:

Embedded image Was added and mixed and reacted at 120 ° C. with stirring. As a result, the viscosity changed over time as shown in Table 3.

[0029]

[Table 3]

Examples 8-9, Comparative Examples 2-3 Silicone oil containing 84 ppm of low molecular weight siloxane having less than 20 siloxane units and having a terminal capped with a trimetysiloxy group (viscosity: 30,150 cP) 5.0g
Was placed in a 25 ml SUS 316 ampoule, 1.0 × 10 ⁻⁴ mol of the compound shown in Table 4 was further added, and the mixture was sealed.
After heating for 22 hours, the content of low-molecular siloxane having 20 or less siloxane units was measured. Table 4 shows the results.

[0031]

According to the present invention, by using a salt of a specific fluorinated carboxylic acid and a basic amino compound as a reaction catalyst, the dehydration-condensation reaction between organopolysiloxanes having Si-OH groups can be rapidly carried out. And a high-molecular-weight organopolysiloxane can be promptly produced without causing cleavage or rearrangement of the siloxane bond.

[Table 4]

Continuing from the front page (72) Inventor Susumu Sekiguchi 1-10 Hitomi, Matsuida-machi, Usui-gun, Gunma Prefecture Inside Silicone Electronic Materials Research Laboratory, Shin-Etsu Chemical Co., Ltd. No. 1-10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (58) Field surveyed (Int. Cl. ⁶ , DB name) C08G 77/08

Claims (1)

(57) [Claims] (1) at least one Si—OH group per molecule;
A method for producing a high molecular weight organopolysiloxane by a dehydration condensation reaction of an organosiloxane having at least one carboxylic acid having at least one fluorine atom bonded to a carbon atom at the α-position of a carboxyl group; Is used in an amount of 0.001 to 10 parts by weight per 100 parts by weight of the organosiloxane, and a salt with a basic amino compound having a hydrogen atom and / or a carbon atom bonded to all the bonds of A method for producing a high molecular weight organopolysiloxane, wherein a dehydration condensation reaction is carried out in the presence of the compound.