JP2797931B2 - Method for purifying (meth) acryl-functional alkoxysilane - 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 purifying an alkoxysilane by removing acidic impurities contained in the (meth) acryl-functional alkoxysilane, and more particularly to a method for purifying an alkoxyhydrosilane and a terminally unsaturated (meth) acrylate compound. The present invention relates to a purification method capable of removing, at a high removal rate, acidic impurities generated during the synthesis of a (meth) acryl-functional alkoxysilane synthesized by a hydrosilylation reaction of

[0002]

2. Description of the Related Art
Known methods for producing alkoxysilanes include a method of esterifying a corresponding halosilane such as chlorosilane, bromosilane, and iodosilane with an alcohol, and a method of introducing an organic functional group into alkoxyhydrosilane by a hydrosilylation reaction.

[0003] In the former method, a halogen component is present, but it is impossible to remove the halogen component by purification by distillation. Therefore, as a method for removing the halogen component (acid content), sodium salt of hindered phenol is used. Is treated with a secondary amine, followed by distillation.
No. 78393 proposes.

On the other hand, the latter method is different from the former method in that a halogen component is not present in the system, so that a halogen-free formulation is obtained, and a step of esterification with an alcohol can be omitted. Has advantages.

However, the present inventor has applied the latter method to the synthesis of a (meth) acryl-functional alkoxysilane, and when the alkoxyhydrosilane and the terminally unsaturated (meth) acrylate compound undergo a hydrosilylation reaction, Along with the (meth) acryl-functional alkoxysilane, various acidic impurities that form (meth) acrylic acid upon contact with (meth) acrylic acid or water are generated in large quantities, and the presence of these impurities is determined by distillation (meth) ) It was confirmed that it was difficult to purify the acrylic-functional alkoxysilane.

When such acidic impurities are mixed in the (meth) acryl-functional alkoxysilane, disadvantages such as hydrolysis and gelation of the alkoxy group with the passage of time occur. No method has been found that can remove methane with a high removal rate.

[0007] The present invention has been made in view of the above circumstances,
It is possible to remove the acidic impurities mixed at the time of synthesizing the (meth) acryl-functional alkoxysilane with a high removal rate, and thus to improve the stability of the (meth) acryl-functional alkoxysilane. It is intended to provide a purification method.

[0008]

Means and Action for Solving the Problems The present inventors have
As a result of intensive studies to solve the above problems, during or after the synthesis of the (meth) acryl-functional alkoxysilane, a neutral or alkaline silylating agent is added to produce by-product (meth) acrylic acid or the like. When the acidic impurities are silylated, these silylated acidic impurities can be easily removed by distillation, and the unreacted silylating agent can also be easily removed because of its low boiling point or solid, so ) It has been found that acidic impurities contained in the acrylic-functional alkoxysilane are removed at a high removal rate, whereby the (meth) acryl-functional alkoxysilane is purified and its storage stability is greatly improved.

In particular, when a (meth) acryl-functional alkoxysilane is synthesized by a hydrosilylation reaction between an alkoxyhydrosilane and a terminally unsaturated (meth) acrylate compound, of the acidic substances produced as impurities by the hydrosilylation reaction, The main substance is (meth) acrylic acid. This (meth) acrylic acid is highly polar and accompanies the target substance, so it is difficult to remove it during distillation, and it is mixed into the target substance after distillation and purification. However, when (meth) acrylic acid is silylated with the silylating agent described above, its polarity decreases,
The inventors have found that an acid component generated during the synthesis of an acrylic-functional alkoxysilane and a component that releases an acid component by moisture can be easily separated by a distillation operation, and the present invention has been accomplished.

[0010] It has also been found that, when applied to a water-crosslinkable resin obtained by, for example, grafting or copolymerizing with a polyolefin or acrylic resin, its storage stability is improved.

Accordingly, the present invention is to provide a (meth) acryl-functional alkoxysilane represented by the following general formula (1) containing an acidic impurity by adding a neutral or alkaline silylating agent to silylate the acidic impurity. The present invention provides a method for purifying a (meth) acryl-functional alkoxysilane, which comprises removing the silylated product by distillation.

[0012]

Embedded image (In the formula, R ¹ is a monovalent hydrocarbon group having 1 to 4 carbon atoms, R ² is a divalent hydrocarbon group having 1 or more carbon atoms, and n is 1, 2 or 3.)

Now, the present invention will be described in further detail. The method for purifying a (meth) acryl-functional alkoxysilane of the present invention comprises a (meth) acryl-functional alkoxysilane represented by the following general formula (1) containing an acidic impurity. A neutral or alkaline silylating agent is added to the mixture to silylate acidic impurities and distillatively remove the impurities.

[0014]

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Here, R ¹ is a monovalent hydrocarbon group having 1 to 4 carbon atoms, and specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group and a butyl group. R ² is a divalent hydrocarbon group having 1 or more carbon atoms, such as methylene, ethylene, propylene, isopropylene, isobutylene, hexene, decylene, undecylene, ethylphenylmethylene, etc. Is exemplified.
R ³ is a hydrogen atom or a methyl group, and n is 1,2.
Or 3.

Examples of the (meth) acryl-functional alkoxysilane represented by the formula (1) include the following.

[0017]

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[0018]

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[0019]

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[0020]

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[0021]

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[0022]

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The above (meth) acryl-functional alkoxysilanes can be obtained by hydrosilylation of the corresponding alkoxyhydrosilanes and terminally unsaturated (meth) acrylic compounds by known methods.

The (meth) acryl-functional alkoxysilane obtained by such a hydrosilylation reaction contains various impurities which produce (meth) acrylic acid by (meth) acrylic acid or water. In the present invention, such an acidic impurity is silylated by a neutral or alkaline silylating agent, and the silylated acidic impurity is removed by distillation.

Here, specific examples of the silylating agent include isopropenoxytrimethylsilane, 1-trimethylsilyl-1,2,4-triazole, 2-trimethylsilyl-1,2,3-triazole, 1-trimethylsililimidazole, N-methyl-N-trimethylsilylacetamide, bis (trimethylsilyl) acetamide, hexamethyldisilazane, hexamethylcyclotrisilazane, diethylaminotrimethylsilane, bis (ethylamino) dimethylsilane, bis (dimethylamino) dimethylsilane, 1-trimethylsilylpyrrole , 1-trimethylsilylpyrrolidine, piperidinotrimethylsilane,
Methyltris (dimethylamino) silane, bis (diethylamino) dimethylsilane, bis (trimethylsilyl)
Urea and the like are exemplified. Of these, isopropenoxytrimethylsilane, hexamethyldisilazane, and hexamethylcyclotrisilazane are particularly preferably used.

The above silylating agent can be added either at the time of synthesizing the (meth) acryl-functional alkoxysilane or after the synthesis. The addition amount, treatment temperature and treatment time of the silylating agent are not particularly limited, but the addition amount is 5 to 20% by weight based on the reaction product, the treatment temperature is room temperature to 100 ° C, and the treatment time is It is preferable to set it for 1 to 5 hours.

After the silylation as described above, the silylated acidic impurities are removed by distillation, whereby the (meth) acryl-functional alkoxysilane is purified. In this case, the impurities are removed by distillation, As a method for purifying silane or the like, a normal vacuum distillation method may be used. After distillation, filtration may be performed if necessary.

The (meth) acryl functional silane treated in this way contains almost no acidic impurities,
The storage stability is greatly improved.

Since the (meth) acrylic compound is liable to undergo radical polymerization due to heat or the like, air ventilation or addition of a polymerization inhibitor during synthesis, processing, or distillation improves the yield. It is effective for

In this case, as the polymerization inhibitor, 2,6-
Di-tert-butyl-p-cresol, hydroquinone, hydroquinone monomethyl ether, 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,
4'-thiobis (6-t-butyl-m-cresol),
1,3,5-trimethyl-2,4,6-tris (3,5
-Di-tert-butyl-4-hydroxybenzyl) benzene, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate, n-octadecyl-3 -(3,5-di-t
-Butyl-4-hydroxyphenyl) propionate,
Phenols such as 7-t-butylhydroquinone;
N′-diphenyl-p-phenylenediamine, N-isopropyl-N′-phenyl-p-phenylenediamine,
Amines such as N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, phenothiazine, copper dimethyldithiocarbamate, dimethyl Examples thereof include dithiocarbamates such as dithiocarbamine tellurium, iron dimethyldithiocarbamate, and zinc dimethyldithiocarbamine; and thiuram-based compounds such as tetraethylthiuram disulfide, tetrabutyl disulfide, and dipentamethylenethiuram tetrasulfide.

[0031]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. Prior to the description of each example, a synthesis example of a (meth) acryl-functional alkoxysilane will be described.

[Synthesis Example] Stirrer, thermometer, reflux condenser,
In a 2 liter separable flask equipped with a dropping device, 759 g (6 mol) of allyl methacrylate, 1,3,5-
7.2 g of trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene,
2,6-di-t-butyl-4-methylphenol 7.2
g, the temperature was raised to 70 ° C., 7.2 g of a toluene solution containing 0.5% of chloroplatinic acid was added, and 805.2 g (6 mol) of trimethoxysilane was added while maintaining the temperature at 70 to 80 ° C. Drop slowly over 1 hour.
The mixture was stirred for 1 hour while maintaining the temperature at 0 ° C., and the synthesis stock solution A containing the (meth) acryl-functional alkoxysilane was
g was obtained.

Example 1 785.1 g of the above synthesized stock solution A
78.2 g of hexamethyldisilazane was added to
For 3 hours, and the mixture was aged for about 15 hours using a distillation apparatus equipped with a reboiler having a capacity of 1 liter and a packed rectification column having a height of 10 cm. Next, the purity and acid content of each distillation cut were determined. Acid content is 0.1
Quantitation was performed by potentiometric titration using an aqueous solution of N sodium hydroxide. Table 1 shows the results. Cuts 4 to 10 were taken as the main distillate and 547.6 g of purified γ-methacryloxypropyltrimethoxysilane (acid content 0.17mo)
1 / kg).

[0034]

[Table 1]

Example 2 A (meth) acryl-functional alkoxysilane was prepared in the same manner as in Example 1 except that 78.2 g of isopropenoxytrimethylsilane was used instead of hexamethyldisilazane used in Example 1. Purification was performed. Table 2 shows the results. In addition, cut 4-1
Using 0 as the main distillate, 495.0 g of purified γ-methacryloxytrimethoxysilane (acid content 0.14 mol / kg) was obtained.

[0036]

[Table 2]

[Comparative Example 1] Distillation was carried out without treating the synthetic stock solution A with a silylating agent.
The purity of methacryloxytrimethoxysilane is 98.7
%, Acid content was 0.32 mol / kg.

[0038]

According to the purification method of the present invention, acidic impurities mixed in the synthesis of the (meth) acryl-functional alkoxysilane can be removed very effectively. The stability of the silane can be improved.

Claims (3)

(57) [Claims] 1. A neutral or alkaline silylating agent is added to a (meth) acryl-functional alkoxysilane represented by the following general formula (1) containing an acidic impurity to silylate the acidic impurity. A method for purifying a (meth) acryl-functional alkoxysilane, wherein the method comprises removing by distillation. Embedded image (In the formula, R ¹ is a monovalent hydrocarbon group having 1 to 4 carbon atoms, R ² is a divalent hydrocarbon group having 1 or more carbon atoms, and n is 1, 2 or 3.) 2. The (meth) acryl-functional alkoxysilane of the formula (1) is obtained by a hydrosilylation reaction between an alkoxyhydrosilane and a terminally unsaturated (meth) acrylate compound, containing (meth) acrylic acid as an acidic impurity. The purification method according to claim 1, wherein 3. The method according to claim 1, wherein the neutral or alkaline silylating agent is selected from isopropenoxytrimethylsilane, hexamethyldisilazane, and hexamethylcyclotrisilazane.