JPH07292115A - Production of polyorganosiloxane having terminal blocked with ketoxime - Google Patents

Abstract

PURPOSE:To continuously produce the subject compound useful for a silicone rubber hardening composition of one-component-type and curing at room temperature by reacting a specific polyorganosiloxane with a specific organosilane at a specific ratio. CONSTITUTION:This compound is obtained by continuously supplying (A) a polyorganosiloxane of formula HO(SiR<1>R<2>O)nH [R<1>, R<2> are each a monovalent or a substituted hydrocarbon; (n)=20-3000] and (B) an organosilane of formula R<3>mSi(0N=X)4-m [R<3> is monovalent or a substituted hydrocarbon; =X is =CR<4>R<5> (R<4> and R<5> are each a monovalent or a substituted hydrocarbon) or the formula (R<6> is a divalent or a substituted hydrocarbon); m=1,2] in such a manner that compounding ratio of the component B to silanol group in the component A is 2.5-1.3 in terms of molar ratio, reacting under homogeneous mixing and subsequently taking out the product successively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously producing a ketoxime group-endblocked polyorganosiloxane having a ketoxime group at both ends of a molecular chain, which is used for a one-component room temperature curable silicone rubber composition. .

[0002]

2. Description of the Related Art So-called condensation reaction type liquid silicone rubber compositions which are cured at room temperature by moisture in the air to become rubber elastic bodies have been well known, and have been widely used in various fields such as construction, machinery and electricity. Sealing material, industrial adhesive,
Widely used as potting material, molding material, etc.

By the way, when such a silicone rubber composition is used as a sealing material for industrial use, construction, structure, etc., from the viewpoint of workability, etc., even if the applied silicone rubber is in an uncured state, it will be applied from the viewpoint of application. It is important not to drip. Therefore, a silicone rubber composition for a sealing material is added with silica treated with an organosilicon compound such as octamethylcyclotetrasiloxane as a reinforcing filler, and further blended with a sag-preventing agent. It was As the anti-dripping agent, polysiloxanes and polyoxyalkylene compounds containing a large amount of phenyl groups are known.

However, in the above-mentioned method of preventing sag, not only the compatibility between the base polymer and the sag inhibitor is poor, but also a large amount of the sag inhibitor must be blended, resulting in high manufacturing cost. There was a problem of becoming.

Therefore, recently, studies have been conducted to improve the drooping property of the silicone rubber composition without using a drooling inhibitor. For example, Japanese Patent Laid-Open No. 2-413
No. 61 discloses that at least two hydroxyl groups bonded to a silicon atom are contained in one molecule, and the viscosity at 25 ° C. is 100 to 50.
Mix 0000cP polyorganosiloxane with organosilane containing at least two ketoxime groups bonded to silicon atom in one molecule in a predetermined ratio, and then mix finely powdered silica and curing catalyst. It is described that a silicone rubber composition having improved drooping property can be obtained.

[0006]

By the way, since diols and ketoxime compounds are generally highly reactive,
By simply mixing the hydroxyl end-blocked polyorganosiloxane and the ketoxime-substituted organosilane at room temperature as described above, a polyorganosiloxane in which both ends of the molecular chain are capped with ketoxime groups can be easily produced. When mixed with a static mixer by a conventional method, a gel-like substance is likely to be generated, and if the reaction is continuously performed for a long time, the static mixer is clogged with the generated gel and the production cannot be continued. The problem has arisen.

The present invention has been made in order to solve the above problems, and a gel of a ketoxime-terminated end-capped polyorganosiloxane used in a one-component room-temperature-curable silicone composition having excellent sag characteristics is used. An object of the present invention is to provide a method for producing a polyorganosiloxane endblocked with a ketoxime group, which enables stable and continuous production without generation of a particulate matter.

[0008]

Means and Actions for Solving the Problems The inventors of the present invention have conducted diligent researches on the reaction between diols and ketoxime compounds and the problem of gelation. As a result, when these two components are mixed by a static mixer or the like. , It was found that the generation of gel was affected by the relative concentration of the ketoxime compound in the early stage of mixing. That is, if the ratio of the ketoxime compound to the hydroxyl groups of the diols is too low or too high, there are parts where the concentration of the ketoxime compound is too low or too high compared to the hydroxyl groups at the initial stage of mixing, and the gel is formed from such parts. I found that it occurs.

The present invention has been made on the basis of such findings, and the method for producing a polyorganosiloxane endblocked with a ketoxime group according to the present invention is as follows: (A) General formula: HO- (SiR ¹ R ² -O) _n -H (1) (In the formula, R ¹ and R ² represent the same or different groups selected from a monovalent hydrocarbon group and a substituted hydrocarbon group,
a polyorganosiloxane n is expressed by the number of range of 20~3000), (B) the general _{^{formula: R 3 m Si (ON =}} X) 4-m ...... (2) ( wherein, R ³ Represents a group selected from a monovalent hydrocarbon group and a substituted hydrocarbon group, = X represents a = CR ⁴ R ⁵ group or an organic group represented by the following formula, and m represents a number of 1 or 2.

[Chemical 2] However, the same or different radicals R ⁴ and R ⁵ is selected from monovalent hydrocarbon radicals and substituted hydrocarbon radicals, R ⁶
Represents a group selected from a divalent hydrocarbon group and a substituted hydrocarbon group) and an organosilane represented by the above (A)
The organosilane of the component (B) is continuously fed to the reactor so that the mixing ratio of the organosilane of the component (B) to the amount of silanol groups in the polyorganosiloxane as the component is in the range of 2.5 to 13, and the mixture is homogeneous in the reactor. After mixing and reacting with
It is characterized in that reaction products are sent out in order. In addition, in the method for producing the above-mentioned polyorganosiloxane having a ketoxime group end-blocked, after mixing the components (A) and (B) in a static mixer, in a feed pipe capable of giving a residence time of 10 minutes or more, The reaction is carried out at a temperature in the range of 20 to 60 ° C., and the components (A) and (B) are continuously fed to the reactor by using a pump whose flow rate can be adjusted by feedback control from a flow meter. It is characterized by supplying.

In the present invention, the component (A) used as the base polymer is a polyorganosiloxane in which both ends of the molecular chain represented by the above formula (1) are blocked with hydroxyl groups. Here, as the organic groups R ¹ and R ² bonded to a silicon atom, monovalent hydrocarbon groups such as methyl group, ethyl group, butyl group, vinyl group and phenyl group, chloromethyl group, cyanoethyl group, trivalent group A monovalent substituted hydrocarbon group such as a fluoropropyl group is exemplified. It is preferable that 85% or more of R ¹ and R ² are methyl groups because they have an appropriate curing rate, the fluidity before curing is appropriate and easy to handle, and the physical properties after curing, especially the modulus are low. From the viewpoint of ease of synthesis, it is desirable that all are methyl groups. However, if heat resistance or cold resistance is required, R ¹
And it is preferable to use a phenyl group as a part of R ² .

The range of n in the above formula (1) is such that
Depending on the type and molar ratio of R ¹ and R ² , (A)
It is preferable to appropriately select the viscosity of the component to be 100 to 500000 cP. If the viscosity of the component (A) is less than 100 cP, it becomes difficult to obtain good physical properties due to the low viscosity, and if it exceeds 500000 cP, the extrusion workability and curability deteriorate. When R ¹ and R ² are all methyl groups, the value of n showing a viscosity of 100 to 500000 cP corresponds to 20 to 3000.

In the present invention, the organosilane of the component (B) to be reacted with the component (A) is an organosilane substituted with a ketoxime group represented by the above formula (2).
Here, as the organic group R ³ bonded to a silicon atom, a monovalent hydrocarbon group such as a methyl group, an ethyl group, a butyl group, a vinyl group or a phenyl group, a chloromethyl group, a cyanoethyl group or a trifluoropropyl group is used. Examples thereof include monovalent substituted hydrocarbon groups, and a methyl group, a vinyl group or a phenyl group is preferable because they give an appropriate curing rate.

Further, = X in the above formula (2) is a = CR ⁴ R ⁵ group or a divalent organic group represented by the above formula (3). Examples of the organic groups R ⁴ and R ⁵ include monovalent hydrocarbon groups such as methyl group, ethyl group, butyl group and phenyl group, and monovalent substituted hydrocarbon groups such as chloromethyl group, cyanoethyl group and trifluoropropyl group. Examples of the organic group R ⁶ include an alkylene group such as an ethylene group, a propylene group, a tetramethylene group, and a hexamethylene group, and a group in which a part or all of hydrogen atoms of these groups are substituted with a halogen atom. And a divalent group such as Furthermore, m is a number of 1 or 2 but preferably m = 1, but m
It may be a mixture with m = 2 containing 90% or more of = 1.

Specific examples of the component (B) include:
Examples are represented by the following formulas (4) to (19).

[0015]

[Chemical 3]

[Chemical 4] Among these, it is preferable to use those represented by the above formulas (5) and (7) from the viewpoint of curability of the final silicone rubber composition.

In the method for producing a polyorganosiloxane endblocked with a ketoxime group according to the present invention, the above-mentioned component (B) is continuously supplied to the reactor together with the above-mentioned component (A). In this reactor, (A) component and (B)
It is important to provide a residence time such that the components are homogeneously mixed and sufficiently reacted. In this way, the components (A) and (B) are reacted under thorough mixing in the reactor and for a sufficient residence time.

The supply ratios of the component (A) and the component (B) are the molar ratio of the organosilane of the component (B) to the amount of silanol groups in the polyorganosiloxane of the component (A),
Ie

[Chemical 5] Set so that the molar ratio of is within the range of 2.5 to 13.

When the blending molar ratio of the organosilane of the component (B) to the amount of silanol groups in the component (A) is less than 2.5, a portion having a low ketoxime concentration occurs at the initial stage of mixing,
A gel-like substance is generated from such a portion. On the other hand, if the blending molar ratio exceeds 13, a portion having a high concentration of ketoxime (a portion having a low concentration of silanol) is generated at the initial stage of mixing, and a gel-like substance is generated from such a portion. Thus, (A)
Even if the blending molar ratio of the organosilane of the component (B) to the amount of silanol groups in the component is less than 2.5 or more than 13, a gelled product is generated in the initial stage of mixing, resulting in elasticity and mechanical properties. It becomes difficult to continuously produce a polyorganosiloxane having both excellent molecular chain ends blocked with ketoxime groups. Therefore, in the present invention, it is important to set the blending molar ratio within the range of 2.5 to 13.

Further, in order to continuously produce a polyorganosiloxane blocked with a ketoxime group, it is necessary to terminate the reaction within a fixed time. For example, 10 after mixing
In order to terminate the reaction in about minutes, it is preferable that the mixing molar ratio of the organosilane of the component (B) to the amount of silanol groups in the component (A) is 2.5 or more, depending on the reaction temperature. That is, when the blending molar ratio is 2.5 or more, the reaction between the component (A) and the component (B) proceeds rapidly, so that the reaction can be terminated in about 10 minutes after mixing. From this point as well, the above mixing molar ratio is
It is important to set it to 2.5 or more. The more preferable range of the above blending molar ratio is 3 to 12, and the most preferable range is 4 to 10.
Is the range.

The water content of the components (A) and (B) after mixing is preferably 0.1% or less, and the reaction is preferably carried out under substantially anhydrous conditions. If the water content after mixing exceeds 0.1%, the amount of gel attached to the reaction device increases, which is not preferable for continuous production.

A static mixer is preferably used as a reactor used for mixing and reacting the components (A) and (B) as described above, and an internal mixture is provided on the outlet side of the static mixer. It is preferable to connect a feed pipe capable of keeping the residence time of 10 minutes or more. The set residence time is set according to the reaction temperature. By using such a reactor, (A)
The component and the component (B) can be mixed and reacted continuously and favorably. Further, the reaction between the component (A) and the component (B) is
In order to proceed rapidly at room temperature or higher, the temperature of the static mixer and the feed pipe connected to the outlet side thereof are preferably adjustable, and the reaction temperature is preferably set in the range of 20 to 60 ° C.

Further, in the production method of the present invention, it is important to control the supply amounts of the components (A) and (B) to the reactor as described above. It is preferable to install a flow rate control device in each of the two raw material feed lines. Examples of such a flow rate adjusting device include a flow meter inserted in the raw material feed line and a feed pump whose flow rate can be adjusted by feedback control from the flow meter. By using such a flow rate controller, the components (A) and (B) can be stably supplied to the reactor from each raw material feed line at a predetermined flow rate ratio. It is possible to stably and continuously produce the polyorganosiloxane end-capped with a ketoxime group while suppressing the generation of a gelled substance, and the production amount thereof can be easily adjusted.

In the production method of the present invention, the polyorganosiloxane of the component (A) and the organosilane of the component (B) are reacted to give a poly (polyethylene) having both ends of the molecular chain represented by the following formulas blocked with ketoxime groups. An organosiloxane is obtained.

[0024]

[Chemical 6] The reaction product produced by the production method of the present invention contains ketoxime and unreacted ketoxime-substituted organosilane as by-products, in addition to the above-mentioned polyorganosiloxane end-capped with a ketoxime group. However, ketoxime is generated when the room temperature curable silicone rubber composition is cured by reacting with water, and the ketoxime-substituted silane is used to secure the stability of the room temperature curable composition. It is added as a ketoxime group about 3 to 20 equivalent times. Therefore, it is not necessary to separate and purify these by-products, and the reaction product according to the production method of the present invention can be used as it is for producing a one-component room-temperature-curable silicone composition.

[0025]

EXAMPLES Examples of the present invention will be described below.

Examples 1 and 2 First, the reactor used in this example will be described with reference to FIG. As shown in the figure, two raw material feed lines 2 and 3 are joined together on the inlet side of the static mixer 1 and connected to each other. Pumps 4 and 5 are inserted in these two raw material feed lines 2 and 3, respectively, and flowmeters 6 and 7 are inserted in the static mixer 1 side from the pumps 4 and 5, respectively. , Pumps 4, 5
The flow rate can be adjusted by feedback control from the flow meters 6 and 7. Further, a feed pipe 8 whose residence time inside is adjusted to about 10 minutes is connected to the outlet side of the static mixer 1.

Using the reactor as described above, polydimethyl having hydroxyl groups at both ends of the molecular chain from the feed line 2 and having a viscosity of 1000 cP and a silanol group content of 7.5 × 10 ^-5 mol / g. Siloxane was supplied to the static mixer 1 at a flow rate of 15 kg / hr, and methyltris (methylethylketoxime) silane was fed from the raw material feed line 2 so that the molar ratio of methyltris (methylethylketoxime) silane to the amount of silanol groups in polydimethylsiloxane was changed. The flow rates shown in the table were supplied so that the ratios shown in Table 1 were obtained. Then, these components were completely mixed by the static mixer 1, and then reacted while passing through the feed pipe 8 to obtain a reaction product. In addition, the static mixer 1
The temperature of the feed tube 8 and the temperature of the feed tube 8 were set to 25 ° C. by using a heater (not shown).

For comparison with the present invention, by changing the feed flow rate of methyltris (methylethylketoxime) silane from the raw material feed line 3, the compounding molar ratio of ketoxime-substituted organosilane / silanol group is less than 2.5 and 13 or less. Except for the above, mixing and reaction were carried out in the same manner as in the above Example to obtain a reaction product.

In this way, polydimethylsiloxane and methyltris (methylethylketoxime) silane were continuously supplied and reacted for 3 hours. After that, the inside of the static mixer 1 is washed with toluene and dried, and then the static mixer 1
The amount of gel attached to each was measured. In addition, the reaction products obtained in the respective examples and comparative examples were treated at 150 ° C. and 2 m, respectively.
After purification under reduced pressure conditions of mHg or less, the molecular weight distribution was measured by gel permeation chromatography (GPC) to determine the average molecular weight (GPC molecular weight). The results of these measurements are also shown in Table 1. The molecular weight of the base oil (dimethylpolysiloxane) before reacting with the ketoxime-substituted organosilane was measured in the same manner. The values are also shown in Table 1. Table 2 shows the GPC analysis conditions.

[0030]

[Table 1]

[Table 2] From the measurement results in Table 1, ketoxime-substituted organosilane /
In each example in which the molar ratio of silanol groups was in the range of 2.5 to 13, in the static mixer gel-like material was not attached,
It was confirmed that gel did not occur even when polydimethylsiloxane having hydroxyl groups at both ends of the molecular chain was continuously reacted with a ketoxime-substituted organosilane for a long time.

In addition,

[Chemical 7] The molecular weight of the group represented by is 215, and the measurement result of the GPC molecular weight of the reaction product obtained in each example is almost the same as the molecular weight when the ketoxime group reacts at both ends of the base oil (polydimethylsiloxane). Match. Therefore, it was confirmed that both ends of the polyorganosiloxane were blocked by the ketoxime group.

As described above, according to the above-described embodiments,
It was possible to continuously and stably produce a polyorganosiloxane having both ends blocked with ketoxime groups.

Examples 3 to 5 The polydimethylsiloxane shown in Table 3 and the ketoxime-substituted organosilane were mixed using the reactor shown in FIG. 1 at the flow rates and molar ratios shown in Table 3 (ketoxime-substituted organosilane / silanol group). ) And mixed and reacted (reaction temperature 25 ° C). After purifying each of the obtained reaction products in the same manner as in Example 1, the GPC molecular weight was measured. Further, the gel amount in the static mixer was measured in the same manner as in Example 1. The results are also shown in Table 3.

[0034]

[Table 3]

[0035]

As described above, according to the production method of the present invention, a gel-like substance is generated from a polyorganosiloxane having both ends of its molecular chain blocked with ketoxime groups by using a static mixer or the like. Instead, it becomes possible to manufacture continuously in a stable manner. And, by using the polyorganosiloxane produced by such a production method of the present invention, a one-pack type room temperature curable silicone in which drooping property before curing is remarkably improved without using a drooling inhibitor. It becomes possible to obtain a composition.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a reaction device used in an example of the present invention.

[Explanation of symbols]

 1 ... Static mixer 2, 3 ... Raw material feed line 4, 5 ... Pump 6, 7 ... Flow meter 8 ... Feed pipe

Claims (3)

[Claims] (A) General formula: HO- (SiR ¹ R ² -O) _n -H (wherein R ¹ and R ² are the same or selected from a monovalent hydrocarbon group and a substituted hydrocarbon group. Shows different groups,
n represents a number in the range of 20 to 3000), and (B) a general formula: R ³ _m Si (ON = X) _4-m (wherein R ³ is a monovalent carbon). A group selected from a hydrogen group and a substituted hydrocarbon group, = X represents a = CR ⁴ R ⁵ group or an organic group represented by the following formula, and m represents a number of 1 or 2. However, the same or different radicals R ⁴ and R ⁵ is selected from monovalent hydrocarbon radicals and substituted hydrocarbon radicals, R ⁶
Represents a group selected from a divalent hydrocarbon group and a substituted hydrocarbon group), and the organosilane of the component (B) with respect to the amount of silanol groups in the polyorganosiloxane of the component (A). Is continuously fed to the reactor so that the blending ratio thereof is in the range of 2.5 to 13, and the mixture is uniformly mixed and reacted in the reactor, and then the reaction products are sequentially sent out. And a method for producing a polyorganosiloxane end-capped with a ketoxime group. 2. The method for producing a polyorganosiloxane endblocked with a ketoxime group according to claim 1, wherein the component (A) and the component (B) are mixed in a static mixer, and then a residence time of 10 minutes or more is applied. A process for producing a polyorganosiloxane end-capped with a ketoxime group, which comprises reacting in a feed tube that can be applied at a temperature in the range of 20 to 60 ° C. 3. The method for producing a polyorganosiloxane endblocked with a ketoxime group according to claim 1, wherein each of the component (A) and the component (B) is provided with a pump whose flow rate can be adjusted by feedback control from a flow meter. A method for continuously producing a polyorganosiloxane endblocked with a ketoxime group, which comprises continuously supplying to the reactor.