JPH115842A - Production of cyclic methylsiloxane oligomer containing si-h bond - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject oligomer continuously and in a good yield by a simple operation from a polymethylhydrogensiloxane having a larger molecular weight than the oligomer. SOLUTION: This method for producing a cyclic methylsiloxane oligomer having Si-H bond, is to perform a siloxane rearrangement reaction of (A) a polymethylhydrogen siloxane selected from (a) a substantially linear polymethylhydrogensiloxane and (b) a cyclic methylhydrogen siloxane oligomer having at least 5 Si-H bonds in a molecule, (B) in the presence of a solid acid catalyst and (C) an alcohol having a boiling point higher than the objective material, being a liquid state at 30 deg.C, and not containing an aliphatic unsaturation in its molecule to obtain (D) a cyclic methylhydrogensiloxane oligomer containing Si-H. Further, the component (D) has a smaller number of Si atom in the molecule than that in the component (b) in the case of using the component (b) as a part or a whole part of the component (A). Also, in the reaction, it is preferable to use (E) a hydrocarbon solvent having a similar condition to the component (C) simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Methylsiloxane having a Si--H bond in the molecule is referred to as methylhydrogensiloxane because of the specific reactivity of the Si--H bond. The present invention
More particularly, the present invention relates to a method for producing a cyclic methyl hydrogen siloxane oligomer, and more particularly to a cyclic methyl hydrogen siloxane oligomer, particularly a cyclic methyl hydrogen siloxane oligomer, which has a substantially linear or a cyclic methyl hydrogen siloxane having more silicon atoms in the molecule than the target substance. The present invention relates to a method for producing methyl hydrogen tetrasiloxane.

[0002]

2. Description of the Related Art Cyclic methylhydrogen siloxane oligomers are used to introduce various organic groups into the cyclic siloxane oligomer by hydrosilylation reaction or the like, utilizing the reactivity of the Si--H bond. Therefore, it is industrially useful as an intermediate material for producing an adhesion imparting agent, a crosslinking agent, and the like for silicone rubber.

[0003] Such cyclic methyl hydrogen siloxane oligomers include methyl hydrogen siloxane units ((CH ₃ ) HSi).
Cyclic siloxane oligomers consisting only of O units (hereinafter referred to as D 'units); and hybrid cyclic siloxane oligomers consisting of the above D' units and dimethylsiloxane units ((CH ₃ ) ₂ SiO units, hereinafter referred to as D units). .
Such a cyclic methyl hydrogen siloxane oligomer is generally synthesized by performing hydrolysis and condensation reaction that proceeds simultaneously with methyldichlorosilane alone or with dimethyldichlorosilane. However, when an asymmetric siloxy unit such as a D ′ unit is present, a linear polysiloxane tends to be formed by a condensation reaction, and the yield of a cyclic methyl hydrogen siloxane oligomer by such a direct synthesis method is low.

In general, the hydrolysis and condensation of dichlorosilanes in the presence of a solvent such as diethyl ether improves the yield of cyclic siloxane. However,
The use of such a highly flammable solvent complicates handling, and the yield of cyclic methyl hydrogen siloxane oligomer is limited even in the presence of the solvent.

In the case of polydimethylsiloxane, a polydimethylsiloxane mixture obtained by hydrolysis and condensation of dimethyldichlorosilane is heated to polymerize in the presence of an alkaline catalyst such as potassium silanolate, and then heated under reduced pressure. It is known that a cyclic dimethylsiloxane oligomer is obtained by performing a siloxane bond rearrangement reaction. However, when a cyclic methyl hydrogen siloxane oligomer is used as the target product, the Si—H bond is easily hydrolyzed in the presence of an alkali catalyst, and thus the target product cannot be obtained by such a method.

Japanese Patent Publication No. 48-30480 discloses Si
A linear polydiorganosiloxane which may contain a -H bond and has a halogen atom at a molecular end thereof, in the presence of an aprotic polar solvent such as dimethyl sulfoxide, in a stoichiometric amount of an alkali metal carbonate; For example, a method for producing a cyclic diorganosiloxane oligomer by reacting with potassium carbonate is disclosed. Although it is possible to apply this method to the production of cyclic methyl hydrogen siloxane oligomers, the reaction involves little rearrangement of siloxane bonds, so depending on the number of silicon atoms in the target oligomer, low molecular weight, terminal It is necessary to use a straight-chain methylhydrogen siloxane oligomer having a halogen atom in the above, and it is difficult to produce the siloxane oligomer with high selectivity. In addition, since a large amount of solid alkali metal carbonate is used, it is difficult to uniformly mix it during the reaction.

[0007] US Pat. No. 3,714,213 discloses that
The intermediate siloxane unit is a D 'unit, and at least one of the three organic groups present in the terminal triorganosilyl group is present.
Disclosed is a method for producing a cyclic polymethylhydrogensiloxane by heating a triorganosilyl-terminated linear polymethylhydrogensiloxane having at least 3 carbon atoms under reduced pressure in the presence of an acidic solid catalyst. However, in this method, a special terminal group such as a dimethylhexylsilyl group or a methyldiphenylsilyl group is required, and the siloxane terminal group or the terminal group is provided by a complicated reaction such as the Grignard method. It is necessary to introduce the above organic groups into the silanes or siloxane oligomers.

Japanese Patent Application Laid-Open No. 2-129192 discloses that a substantially linear polymethylhydrogensiloxane is dropped onto a high-temperature acidic solid catalyst bed under reduced pressure to recover the produced low-molecular-weight polymethylhydrogensiloxane. A method is disclosed. However, in this method, when a polymethyl hydrogen siloxane having a trimethylsilyl group as a terminal group is used as a starting material, the linear methyl siloxane oligomer having the terminal group is mixed into the cyclic methyl hydrogen siloxane oligomer generated by the siloxane rearrangement reaction. Is inevitable, and the separation by distillation becomes complicated. In addition, when a linear polymethylhydrogensiloxane having no trimethylsiloxy group in the molecule, that is, having a silicon functional group at the molecular terminal is used as a starting material, a gel-like high molecular weight polymethylhydrogensiloxane is produced with the passage of time. To hinder the continuation of the reaction.

Polymer by Wright et al., 11: 464-
On page 471 (1969), a linear methyl hydrogen siloxane oligomer is obtained by reacting a linear polymethyl hydrogen siloxane at a low temperature such as 0 ° C in the presence of n-butyllithium as a catalyst and tetrahydrofuran as a promoter. A method is disclosed. However, this method
It is necessary to react at a low temperature in order to prevent a side reaction, and n-butyllithium is difficult to handle because it is unstable to oxygen and moisture in the air.

JP-A-8-109187 discloses a product containing a linear polymethylhydrogensiloxane obtained by contacting methyldichlorosilane with a stoichiometric amount of water.
A method is disclosed for contacting an acidic catalyst in the presence of an inert solvent such as a hydrocarbon to obtain a cyclic methylhydrogen siloxane oligomer. However, when the reaction is carried out by a continuous method, the viscosity of the system increases with the passage of time to form a gel, and the production of the cyclic methyl hydrogen siloxane oligomer stops.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for continuously producing a cyclic methyl hydrogen siloxane oligomer from polymethyl hydrogen siloxane having a higher molecular weight with a simple operation in a high yield. is there.

[0012]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the present inventors have found that the present invention has substantially a chain or a ring having more silicon atoms in the molecule than the target. Polymethyl hydrogen siloxane, when performing a siloxane rearrangement reaction in the presence of an acidic solid catalyst, found that the object can be achieved by using a high-boiling alcohol and a high-boiling hydrocarbon solvent in combination to achieve the present invention. It was completed.

That is, the method for producing a cyclic methyl hydrogen siloxane oligomer of the present invention comprises the steps of (A) (A1), a substantially linear polymethyl hydrogen siloxane, and (A2) having at least 5 silicon atoms in the molecule. A polymethyl hydrogen siloxane selected from the group consisting of cyclic methyl hydrogen siloxane oligomers is subjected to a siloxane rearrangement reaction in the presence of an acidic solid catalyst (B) to form a cyclic methyl hydrogen siloxane oligomer (C). When (A2) is used as part or all, (A2) the number of silicon atoms in the molecule is smaller than that of (A2)). Higher than 30 ° C., which is liquid at 30 ° C., and does not contain an aliphatic unsaturated bond in the molecule. Further, in the production method of the present invention, the siloxane rearrangement reaction is carried out, together with (D), by (E) having a boiling point higher than that of (C), being liquid at 30 ° C., and containing an aliphatic unsaturated bond in the molecule. It is preferred to do so in the presence of no carbohydrates.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The polymethylhydrogensiloxane (A) used as a starting material in the present invention comprises the following (A1)
And (A2), a single compound or a mixture of two or more compounds. When (A1) and (A2) are used together, the ratio may be set arbitrarily.

(A1) is a substantially linear polymethylhydrogensiloxane, and ignoring the branched structure which may be present in a small amount, the general formula (I):

Embedded image (X represents a monovalent group selected from the group consisting of a hydroxyl group, a chlorine atom and an alkoxyl group, and may have a small amount of a trimethylsiloxy group; R represents a methyl group or a hydrogen atom; N is an integer of 0 or more). Although a trace amount of a branched structure may be present, the objective product (C) does not contain a polysiloxane oligomer having a siloxane unit other than D 'and D as an impurity, and thus may not have a branched structure. preferable. Note that, in this specification, a general formula representing polysiloxane indicates the number of siloxane units that constitute the polysiloxane unit, and when a plurality of siloxane units are indicated, it does not mean a block copolymer, and the arrangement of siloxane units is Optional.

X is a monovalent group selected from the group consisting of a hydroxyl group, a chlorine atom and an alkoxyl group as described above, and may be one kind or two or more kinds. Since condensation proceeds even in the absence state,
It is preferable that at least 50% is a hydroxyl group, and it is most preferable that substantially all of them are a hydroxyl group from the viewpoint of easy control of the reaction. Chlorine atoms remain at the ends of molecular chains when a small amount of water, particularly less than a stoichiometric amount of water, is used to hydrolyze chlorosilanes. preferable. Further, an alkoxyl group such as methoxy, ethoxy, propoxy and butoxy is present at a part or the whole of a molecular chain terminal depending on conditions when hydrolysis is performed in the presence of a corresponding alcohol. In addition, a small amount of a trimethylsiloxy group may be present, but it is preferable that the trimethylsiloxy group does not exist because the target cyclic methyl hydrogen siloxane oligomer does not contain a linear polysiloxane oligomer as an impurity. The residue obtained by distilling the cyclic methyl hydrogen siloxane oligomer (C) from the product of the siloxane rearrangement reaction of the present invention as described below is referred to as (A)
When reused as 1), a higher alkoxyl group corresponding to the alcohol used in the above rearrangement reaction may be present as X.

M + n may be within a range in which (A1) is stably present and (A1) or (A) containing the same does not lose fluidity, and is generally from 10 to 3,000, preferably from 20 to 3,000. 500. The ratio of m and n is appropriately selected according to the target ratio of a and b in (C).

(A2) is a cyclic methyl hydrogen siloxane oligomer having at least 5 silicon atoms in the molecule, and represented by the general formula (II):

Embedded image (P is an integer of 1 or more, q is an integer of 0 or more,
p + q is an integer of 5 or more). Examples of such cyclic methyl hydrogen siloxane oligomer include 1,3,5,7,9-pentamethylcyclopentasiloxane, 1,1,3,5,7,9-hexamethylcyclopentasiloxane, 1,1,1 3,5,5,7,9-heptamethylcyclopentasiloxane, 1,1,3,5
Cyclic pentasiloxanes such as 5,7,7,9-octamethylcyclopentasiloxane, 1,1,3,3,5,5,7,7,9-nonmethylcyclopentasiloxane and isomers thereof; Similarly, a cyclic hexasiloxane, a cyclic heptasiloxane, and a cyclic octasiloxane having a methyl group bonded to a silicon atom and a Si—H bond are exemplified. Of these, they can be easily synthesized,
Cyclic pentasiloxane is preferred because of its low boiling point and excellent fluidity, but other cyclic methyl hydrogen siloxane oligomers may be included.

(A) is (A1) and / or (A)
2), and may be a mixture of both. (A)
For example, it can be obtained by hydrolyzing methyldichlorosilane with water, or co-hydrolyzing methyldichlorosilane and dimethyldichlorosilane optionally mixed according to purpose with water. During the hydrolysis, a lower alcohol such as methanol, ethanol, n-propanol, isopropanol, or n-butanol may coexist. The silanol compound generated by such a hydrolysis reaction is condensed in the presence of by-produced hydrogen chloride, and is often a linear methyl hydrogen polysiloxane (A1) and a cyclic methyl hydrogen siloxane oligomer ( A2) and, depending on the conditions, are obtained in the form of a mixture of (A ') cyclic methyl hydrogen siloxane oligomers having a lower degree of polymerization, ie having 3 or 4 silicon atoms in the molecule. The mixture containing (A ′) may be used as the starting material of the present invention as it is, and the above (A ′) is separated and recovered by a method such as distillation, and the same as (C) obtained by the present invention, It may be used as various intermediates, and the residue may be used in the present invention as (A). Alternatively, the hydrolyzed condensate thus obtained or the high-boiling residue thereof is subjected to a siloxane rearrangement reaction by any method, preferably the method of the present invention, and a cyclic polymethyl hydrogen having a low degree of polymerization is obtained from the reaction product. The residue obtained by distilling off the siloxane oligomer may be used as (A).

As (A), a mixture of (A1) and (A2) obtained by the above method may be separated into (A1) and (A2) by a method such as distillation, and one of them may be used. . When dimethyldichlorosilane is used in combination as the raw material chlorosilane, a small amount of Si-
Although linear or cyclic (A ″) polydimethylsiloxanes having no H bond are produced, they can be used after being cleaved by a siloxane rearrangement reaction, so that the polydimethylsiloxane remains contained as an impurity ( A) can be used.

(B) used in the present invention is obtained by rearranging the (A ') and / or (A ") siloxane bonds present together with (A) and optionally (A),
It is a catalyst for a siloxane rearrangement reaction that produces (C) described below. Examples of (B) are acid clay and acidic zeolite which are themselves acidic; and clay, bentonite, montmorillonite, zeolite, carbon black, etc., which have been treated with an acid such as sulfuric acid or phosphoric acid, or fluorine. Activated clay, that is, acid-treated clay, is preferred because a high reaction rate can be obtained.

The feature of the present invention is that (A)
Optionally together with (A ′) and / or (A ″), when the siloxane is rearranged by the catalysis of (B) to obtain (C), the system comprises (D) a higher alcohol, and preferably (E) The presence of a hydrocarbon solvent.

(D) is an alcohol having a higher boiling point than that of (C), which is liquid at 30 ° C., and containing no aliphatic unsaturated bond in the molecule. (D) is effective as a solvent for the reaction system together with (E) in controlling the reaction, and is a linear siloxane formed by opening (A1) and (A2) by the reaction during the siloxane rearrangement reaction. A higher alkoxyl group is bonded to the terminal of the polymethyl hydrogen siloxane to prevent an increase in the viscosity of the system and the formation of a gel-like substance, thereby contributing to keeping the system stable during a continuous reaction.

When the target product (C) is a cyclic methyl hydrogen tetrasiloxane, (D) has a boiling point of 165 of D'D ₃ .
Alcohols having a boiling point higher than ° C are used. Such alcohols include 1-heptanol, 1-heptanol
Octanol, 2-octanol, 2-ethylhexanol, 1-nonanol, 3,5,5-trimethyl-1-
Hexanol, 1-decanol, 2-decanol, 1-
Linear or branched aliphatic monohydric alcohols such as undecanol, 2-dodecanol, 4,6,8-trimethylnonanol; alicyclic monohydric alcohols such as 4-methylcyclohexanol; benzyl alcohol; Aromatic monohydric alcohols such as phenylethyl alcohol; and 1,5-pentanediol, 2-ethyl-
Polyhydric alcohols such as 1,3-hexanediol are exemplified, and monohydric alcohols are preferred because they are excellent in suppressing the increase in viscosity of the system and have good compatibility with (E) at the reaction temperature. Further, from the viewpoint of easy separation from the target substance and recovery of (D), those having a boiling point of 150 to 320 ° C are preferable, those having a boiling point of 170 to 280 ° C are more preferable, and those having a boiling point of 190 to 260 ° C are particularly preferable.

(E) is a hydrocarbon having a higher boiling point than that of (C), which is liquid at 30 ° C., and having no aliphatic unsaturated bond in the molecule. (E) is a reaction solvent, which is effective for promoting the siloxane rearrangement reaction with good control. In addition, due to the presence of (E), (A)
And / or a Si—H bond in the molecule of (C) and (A)
Can prevent the Si—H bond in (A) from being damaged by the reaction with the molecular terminal of (A) or (D).

When the target product (C) is a cyclic methyl hydrogen tetrasiloxane, (E) is a compound having a boiling point of 165 of D'D ₃ .
Hydrocarbons having a boiling point higher than ° C are used. Such hydrocarbons include linear or branched aliphatic hydrocarbons such as n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane and isomers thereof; p-menthane , Alicyclic hydrocarbons such as decalin; butylbenzene, pentylbenzene, hexylbenzene, octylbenzene, nonylbenzene, cyclohexylbenzene, p-cymene, diethylbenzene,
Examples include aromatic hydrocarbons such as dipentylbenzene and tetralin, which suppress the temperature rise of the reaction system to prevent the breaking of Si-H bonds, and facilitate separation from the target substance and recovery of (E). Therefore, those having a boiling point of 150 to 260 ° C are preferable, those having a boiling point of 160 to 250 ° C are more preferable,
Those having a temperature of 80 to 220 ° C are particularly preferred.

(C) obtained by the siloxane rearrangement reaction of the present invention is a cyclic methyl hydrogen siloxane oligomer. When (A2) is used as part or all of (A), it is formed by the rearrangement reaction. And (A2) are cyclic methyl hydrogen siloxane oligomers having a smaller number of silicon atoms in the molecule. That is, (C)
Has the general formula (III):

Embedded image (A is an integer of 1 or more, b is an integer of 0 or more,
a + b is an integer of 3 or more and less than p + q). As (C), a cyclic methylhydrogentetrasiloxane wherein a + b is 4, that is, 1,3,5,7-tetramethylcyclotetrasiloxane, 1,1 , 3,5,7-pentamethylcyclotetrasiloxane, 1,1,3,5,5,
7- and 1,1,3,3,5,7-hexamethylcyclotetrasiloxane and 1,1,3,3,5,5,
7-Heptamethylcyclotetrasilotesan is preferred.
When a D unit is contained in the starting material, D ′ in the starting material
Depending on the ratio of units to D units, they are formed as a mixture of the current siloxane oligomers described above and, if necessary, separated from one another by methods such as distillation. Starting from a polymethyl hydrogen siloxane consisting of D 'units only,
A siloxane redistribution reaction for 3,5,7-tetramethylcyclotetrasiloxane can also be performed. In addition, a small amount of a cyclic methyl hydrogen trisiloxane wherein a + b is 3, ie 1,3,5-trimethylcyclotrisiloxane, 1,1,3,5-tetramethylcyclotrisiloxane and / or 1,1,3 , 3,5-pentamethylcyclotrisiloxane may be by-produced,
It can be separated from cyclic methyl hydrogen tetrasiloxane by distillation. If necessary, a macrocyclic methyl hydrogen siloxane oligomer such as cyclic methyl hydrogen pentasiloxane can be obtained as (C) using (A1) as a starting material.

The method for producing a cyclic methyl hydrogen siloxane oligomer of the present invention can be carried out, for example, by the apparatus shown in FIG. 1 or FIG. First, (A), that is, (A1) and / or (A2), together with (A ′) and / or (A ″) which may be present in the system, are charged to the reactor (1), and (B), (D) and preferably (E) are also charged to reactor (1).

The amount of (B) used is such that a sufficient reaction rate can be obtained, so that the total amount of polymethylsiloxane, that is, (A) and possibly (A ') coexist,
It is usually 0.5 to 30 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the total amount containing (A ″).

The amount of (D) used is the total amount of polymethylsiloxane, that is, (A) and the total amount including (A ′) and (A ″) which may coexist; and the solvent, ie, (D) and optionally Usually 0.1 to 95% by weight based on the total amount of (E) used, the effect of preventing the loss of Si-H bonds due to side reactions, preventing the increase in viscosity of the system and the formation of gel-like substances. Therefore, the content is preferably 0.5 to 80% by weight.

The amount of (E) used is the total amount of polymethylsiloxane, that is, (A) and the total amount including (A ′) and (A ″) which may coexist; and the solvent, that is, (D) and (E) Is usually 95% by weight or less with respect to the total amount of the above.
90% by weight is preferred.

The amounts of (D) and (E) optionally used above apply to the amounts based on the total polymethylsiloxane at the beginning of the siloxane rearrangement reaction, and also during the reaction, the respective amounts present in the reaction system. The quantity also applies. That is, as (C) formed by the reaction and some (D) and / or (E) volatilize out of the reaction system, the amount of total polymethylsiloxane, (D) and (E) in the system Changes. Further, as described later, (A) or a raw material siloxane containing the same, (D) and / or (E) is supplied to the reaction system so as to replenish it, and the reaction is allowed to proceed continuously. Can also. In such cases, (D) and (E)
The reaction conditions and the supply amount are adjusted so that the amount of the compound falls within the above range.

The siloxane rearrangement reaction is usually carried out at 30 to 13
0 ° C, preferably 40 to 120 ° C, more preferably 5 ° C.
The reaction can be performed at a reaction temperature of 0 to 80 ° C. If it is lower than 30 ° C., the reaction temperature is slow, and if it exceeds 120 ° C., especially if it exceeds 130 ° C., a part of Si—H bond reacts, and the molecular terminal of (A1) bonds to the silicon atom to form a siloxane bond. Therefore, not only is the Si—H bond consumed, but also the branched structure of the siloxane skeleton is formed, and the viscosity of the system is sharply increased. In an extreme case, a network-like gel is formed.

The siloxane rearrangement reaction proceeds even at normal pressure. In this case, the ring-opening of (A2) in (A) and optionally the cyclic dimethylsiloxane oligomer in (A ') and / or (A ") also proceed simultaneously. Due to (D) present in the system, an alkoxyl group is bonded to the end of the siloxane chain to prevent macromolecule formation by ring-opening polymerization and assist in the formation of (C) by rearrangement reaction. It is effective to promote the formation of (C) by reducing the pressure of the reaction system so that the (C) is volatilized out of the reaction system, thereby causing the rearrangement reaction to proceed in the direction of depolymerization. The reaction pressure is usually 5 to 30 Torr, preferably 10 to Torr.
20 Torr. When the pressure exceeds 30 Torr, the boiling point of the system containing the reaction product becomes high, so that the reaction temperature rises and Si-
The H bond is likely to react, which may increase the viscosity of the system or cause gelation.

As described above, in order to proceed the siloxane rearrangement reaction in the direction of forming (C), the reaction proceeds according to the reaction conditions under which (C) volatilizes from the reactor (1). (C) removed from the system was volatilized at the same time (D)
Alternatively, preferably together with (D) and (E), as shown in FIG. 1, liquefied by a cooler (2) connected to a reactor (1), and stored in a receiving tank (3).

Alternatively, as shown in FIG. 2, a distillation column (4), a top cooler (5) and a reflux distributor (6) are connected to the reactor (1) to convert the volatile (C). Some, as well as (D) or preferably (D) with a higher boiling point than (C)
And at least a part of (E) can be returned to the reactor (1). The remaining distillate is further stored in the receiving tank (3) via the cooler (7). Keep the reaction system stable, (C)
It is preferable to use an apparatus as shown in FIG. 2 because a distillate having a high content of is obtained and the amount of (D) and (E) used can be reduced. The reaction and distillation conditions may be set so that only (C) is distilled off, or set so that (C) is distilled off together with at least a part of (D) and / or (E). Is also good.

By supplying (A) to the reactor (1) so as to compensate for the decrease in (A) in the system as the depolymerization proceeds by the siloxane rearrangement reaction, (C) can be continuously produced. . By controlling the reaction conditions as described above, an increase in the viscosity of the system and the formation of a gel-like substance can be prevented, and the reaction can be continued for a long time.

The supply of (A) may be continuous or intermittent, but it is preferable to continuously supply it in order to keep the reaction system stable. (A) may be supplied together with (A ′) and / or (A ″) in the same manner as (A) initially charged in the reactor (1).
For example, the (A) is introduced into the reaction solution from the raw material tank (8) shown in FIG. 1 or FIG. 2 by the supply pipe (9) so as to participate in the siloxane rearrangement reaction through the reaction system. preferable.

When at least a part of (D) and / or (E) is distilled off, an amount of (D) corresponding to the amount of distilling off is removed.
And / or (E) are fed to the reactor (1). These solvents may be supplied separately from (A) or may be mixed with (A). Further, as the siloxane redistribution reaction proceeds, (B) deteriorates and the catalytic ability decreases, and (C)
When the production rate of (B) decreases, (B) may be appropriately replenished by a method of dispersing (B) in the supply liquid or introducing it from a separate supply port.

(C) which was distilled and stored in the receiving tank (3),
Alternatively, from the mixture of (C) and (D) and / or (E), various cyclic polymethylhydrogensiloxanes can be obtained by rectification, if necessary. (D) and / or (E) in the distillate is obtained as a high-boiling residue by this rectification and can be reused as it is or after further purification by a method such as rectification.

By the above rectification, the cyclic methyl hydrogen siloxane oligomer obtained as a high-boiling residue, for example, cyclic methyl hydrogen pentasiloxane, and the polymethyl hydrogen siloxane remaining in the reactor (1) after the completion of the siloxane redistribution reaction are: In any case, the (D) and / or (E) present can be separated by distillation, or can be reused as a raw material (A) in a mixture with (D) and / or (E).

[0042]

According to the method of the present invention, the cyclic methyl hydrogen siloxane oligomer (C), particularly the cyclic methyl hydrogen tetrasiloxane, can be continuously produced in a high yield by a simple operation. In particular, by combining the reactor with a distillation column, the reaction solvent can be returned to the reactor to continue the reaction, and a large amount of the solvent can be recovered as a distillate and the trouble of reusing can be avoided.

The method of the present invention can be combined with a conventional method for producing polymethylhydrogensiloxane by hydrolysis of methyldichlorosilane or cohydrolysis of silane with dimethyldichlorosilane to obtain a good overall yield from methyldichlorosilane. A cyclic methyl hydrogen siloxane oligomer can be produced. Furthermore, various polymethyl hydrogen siloxanes, such as the by-product of the siloxane redistribution reaction of the present invention, can be used in the production method of the present invention, so that the overall yield of cyclic methyl hydrogen siloxane oligomer can be further improved. Can be.

The cyclic methyl hydrogen siloxane oligomer obtained by the present invention is extremely useful as an intermediate material for producing an adhesion-imparting agent for silicone rubber, a crosslinking agent, and the like.

[0045]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. In the examples, parts are parts by weight. The present invention is not limited by these examples.

Example 1 As a reaction raw material, 748 parts of methyldichlorosilane and 452 parts of dimethyldichlorosilane were co-hydrolyzed, the obtained oily substance was separated from the aqueous phase, and the remaining by-product hydrogen chloride was removed by washing with water. Then, siloxane a, which was obtained by dehydration, having a composition and viscosity shown in Table 1 and being a polymethyl hydrogen siloxane mixture containing some polydimethylsiloxane, was used.

As a catalyst, a montmorillonite clay was activated by sulfuric acid treatment and passed through a 200 mesh 80%
Activated clay having a particle size of.

[0048]

[Table 1]

A siloxane rearrangement reaction was performed using the apparatus shown in FIG. Siloxane a having the composition shown in the column of charged composition in Table 2 and two kinds of solvents were charged into the reactor (1),
Then add activated clay and stir to suspend the activated clay,
The reactor was evacuated to 150 Torr while stirring.
Raise the temperature to 65 ° C, gradually lower the pressure while heating,
After 20 minutes, when the temperature was set to 70 ° C. and the pressure was set to 12 Torr, the cyclic siloxane oligomer produced by the rearrangement reaction was distilled out together with n-decane and 1-nonanol. While maintaining these reaction conditions, as the reaction progresses,
To track the amount and composition of distillate and to compensate for the loss of liquid phase,
Siloxane a, n-decane and 1-nonanol were continuously fed. In addition, activated clay was added twice in the middle.
Substantially all of the cyclic siloxane oligomer distilled out was a cyclic tetrasiloxane, and the composition reached a substantially steady state six hours after the start of the reaction. The reaction was run continuously for 48 hours. The respective additional feeds supplied in the meantime and the total amount of distillate were as shown in Table 2.

[0050]

[Table 2]

FIG. 3 shows the change in the ratio of the solvent to the cyclic methyl hydrogen siloxane oligomer in the obtained distillate with the reaction time, and the change in the cyclic methyl hydrogen siloxane oligomer in the oligomer with the reaction time. As shown in FIG.

Examples 2 to 4 In order to examine the effect of the solvent on the siloxane rearrangement reaction, the rearrangement reaction was carried out by changing the amount of the solvent as shown in Table 3. As a starting material, a polymethylsiloxane containing a small amount of polydimethylsiloxane, having the composition, D 'unit content and viscosity shown in Table 1, obtained by distilling off most of the cyclic tetrasiloxane fraction from siloxane a by distillation Siloxane b, which is a siloxane mixture, was used.

The amounts of 1-nonanol and n-decane were changed as shown in Table 3, and the temperature was raised to 75 ° C. under normal pressure, and the temperature was maintained for 12 hours to obtain the cyclic methyl hydrogen tetrahydrochloride present in the reaction system. The amount of siloxane was followed by analysis by gas chromatography. As a result, as shown in Table 3, when 1-nonanol and n-decane were used in combination, a larger amount of cyclic methylhydrogentetrasiloxane was produced than when 1-nonanol was used alone as the solvent.

[0054]

[Table 3]

Example 5 and Comparative Example 1 A similar experiment of siloxane rearrangement reaction was carried out by using siloxane b as a starting material and using 1 as a solvent as shown in Table 4.
The test was carried out at normal pressure and 120 ° C. using only -nonanol (Example 5) or n-decane alone (Comparative Example 1). The viscosity at 25 ° C. of a sample obtained by successively collecting up to 11 hours following the course of the reaction was measured. As a result, as shown in FIG. 5, the change in the viscosity of the reaction system was hardly recognized in Example 5, whereas the viscosity of the reaction system was increased in Comparative Example 1. The amount of D 'units based on the total siloxane in the sample collected after 5 hours of the reaction was determined by measuring the effective hydrogen amount. As shown in Table 4, the decrease in the D 'unit was small in Example 5, whereas the decrease in the D' unit was significant in Comparative Example 1, and the Si-H bond in the siloxane was reacted. It is considered that the viscosity of the reaction system increased.

[0056]

[Table 4]

Example 6 As shown in FIG. 2, siloxane a was used as a starting material, and a siloxane rearrangement reaction was carried out by an apparatus having a distillation column (4) having eight theoretical plates on a reactor (1). Was. That is, in the same procedure as in Example 1, the composition shown in Table 5 was used.
Siloxane a, two kinds of solvents and activated clay were charged into the reactor (1), and the pressure was reduced to 150 Torr. 60
C., and the pressure was gradually lowered. After 1 hour, the temperature was set to 65.degree. C. and the pressure to 12 Torr, and the top temperature of the distillation column (4) was set to 47.degree. Distillation was observed. The reaction was continued for 6 hours while maintaining the reaction conditions at a reflux ratio of 3, during which the composition of the distillate was monitored as in Example 1. The results were as shown in FIGS.

The distilling cyclic siloxane oligomers were all cyclic tetrasiloxanes. As is apparent from FIG. 6, the concentration of the cyclic siloxane oligomer in the distillate was reduced by providing a distillation column (4) and returning the higher boiling n-decane and 1-nonanol to the reactor (1). In addition, the complexity and economic loss of recovering a large amount of solvent for reuse could be avoided.

Example 7 Using the same apparatus as in Example 6, the starting materials having the same composition as in Example 6 were charged into the reactor as shown in Table 5, and the siloxane rearrangement reaction was carried out according to the same procedure and conditions. Was done. From the stage where the distillate was obtained from the top, the amount and composition of the distillate were tracked, and the corresponding siloxane a and solvent were continuously supplied. During the reaction, activated clay was added every 6 hours. In this way, three hours after the distillate was obtained, the composition of the distillate was almost in a steady state. In this state, the reaction was continued for 24 hours to obtain a distillate shown in Table 5 as a total amount. Table 5 shows the amount of additionally supplied siloxane a, the amount of solvent and activated clay, and the composition of the distillate over the entire period.

[0060]

[Table 5]

Example 8 Using the same apparatus as in Example 6, siloxane a, two kinds of solvents of decalin and 1-nonanol and activated clay having the compositions shown in Table 5 were charged into the reactor (1), and the pressure was increased. 150To
The pressure was reduced to rr. The temperature was raised to 60 ° C., and the pressure was gradually lowered. After one hour, the temperature was set to 65 ° C., the pressure was set to 20 Torr, and the top temperature of the distillation column (4) was set to 47 ° C. Distillate was found. With the reflux ratio set to 3, while maintaining the reaction conditions, the amount and composition of the distillate were traced as the reaction progressed, and siloxane a, decalin and 1
-Nonanol was fed continuously. Activated clay was added every 6 hours on the way, and the reaction was continuously continued for 24 hours.

Substantially all of the cyclic siloxane oligomer distilled out was a cyclic tetrasiloxane, and the composition reached almost a steady state in 3 hours from the start of the reaction. The total amount of each additional component and each component in the distillate fed during the reaction was as shown in Table 5.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a reaction apparatus for carrying out the present invention.

FIG. 2 is a conceptual diagram illustrating an example of a reaction apparatus for implementing the present invention (an example in which a distillation column is provided).

FIG. 3 is a graph in which a ratio of a solvent and a cyclic methyl hydrogen siloxane oligomer in a distillate obtained in Example 1 is plotted according to a reaction time.

FIG. 4 is a graph plotting the composition ratio of a cyclic methyl hydrogen siloxane oligomer in the distillate obtained in Example 1 according to the reaction time.

FIG. 5 is a graph showing the change over time of the viscosity of the reaction system in Example 5 and Comparative Example 1.

FIG. 6 is a graph in which the ratio of a solvent to a cyclic methyl hydrogen siloxane oligomer in the distillate obtained in Example 6 is plotted according to reaction time.

FIG. 7 is a graph in which a composition ratio of a cyclic methyl hydrogen siloxane oligomer in a distillate obtained in Example 6 is plotted according to a reaction time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor 2 Cooler 3 Receiving tank 4 Distillation tower 5 Top cooler 6 Reflux distributor 7 Cooler 8 Raw material tank 9 Supply pipe

Claims (8)

[Claims] (A) (A1) a substantially linear Si—
(A2) Si-H bond-containing polymethylsiloxane selected from the group consisting of Si-H bond-containing cyclic methylsiloxane oligomer having at least 5 silicon atoms in the molecule,
(B) A siloxane rearrangement reaction is carried out in the presence of an acidic solid catalyst, and (C) a Si—H bond-containing cyclic methylsiloxane oligomer (however, when (A2) is used as a part or all of (A), (A2) the number of silicon atoms in the molecule is smaller than that of (A2), wherein the siloxane rearrangement reaction comprises: (D) a boiling point higher than (C), a liquid state at 30 ° C., A method for producing a cyclic methylsiloxane oligomer having a Si—H bond, wherein the method is carried out in the presence of an alcohol containing no aliphatic unsaturated bond. 2. The siloxane rearrangement reaction further comprises (E) a boiling point higher than (C) and a liquid state at 30 ° C.
The production method according to claim 1, wherein the production is carried out in the presence of a hydrocarbon containing no aliphatic unsaturated bond in the molecule. 3. The amount of (D) in the system is the total polymethylsiloxane, (D), and optionally (E).
The amount is 0.5 to 80% by weight based on the total amount of
Or the production method according to 2. 4. The amount of (E) in the system is from 10 to 9 based on the total amount of all polymethylsiloxanes, (D) and (E).
3. The method according to claim 2, wherein the amount is 0% by weight. 5. The method according to claim 1, wherein (B) is activated clay. 6. The method according to claim 1, wherein (C) is a cyclic methyltetrasiloxane containing a Si—H bond. 7. The method according to claim 1, wherein the reaction is carried out at 50 to 120 ° C.
The manufacturing method as described. 8. The process according to claim 1, wherein the siloxane redistribution reaction is carried out while returning at least part of (D) or (D) and (E) to the reactor by distillation.