JPH07278307A - Production of alkoxy group-containing silicone resin - Google Patents

Abstract

PURPOSE:To provide a method for producing an alkoxy group-containing liquid silicone resin free from solvent, capable of readily carrying out control of a composition and viscosity of a silicone resin, alkoxy group content, etc. CONSTITUTION:This method for producing an alkoxy group-containing liquid silicone resin free from solvent comprises reacting an alkoxysilane expressed by the formula, R<1>nSi(OR<2>)4-n [R<1> is a monofunctional hydrocarbon residue which may be replaced with a halogen atom; R<2> is a 1-4C alkyl; (n) is an integer of 0 or 2] or its partially hydrolyzed condensate or their mixture with water in an amount of about 0.2-0.5mol based on 1mol of alkoxy group contained in the raw material under acidic conditions and removing the resultant alcohol.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a solventless liquid silicone resin containing an alkoxy group. More specifically, the present invention relates to a method for producing a solventless alkoxy group-containing liquid silicone resin in which composition, viscosity, alkoxy group content, etc. can be easily controlled.

[0002]

BACKGROUND ART Alkoxy group-containing liquid silicone resins are known as silicone varnishes for modifying organic resins, and are used as binders for electrically insulating materials that require heat resistance and coatings for heat resistant paints. Widely used as an agent and weathering vehicle. Conventionally, such an alkoxy group-containing liquid silicone resin has the following four types of chlorosilanes, that is, methyltrichlorosilane, dimethyldichlorosilane, phenyltrichlorosilane and diphenyldichlorosilane, which are blended with one or more types depending on the purpose of use and water. It is produced by a hydrolysis condensation reaction in a mixed liquid of alcohol. However, in this production method, since chlorosilane having a very high hydrolysis rate such as methyltrichlorosilane is used as a raw material, there is a problem that gelation occurs when the amount of water used is increased. Therefore, the compounding amount of methyltrichlorosilane is limited, and it is necessary to mix a large amount of chlorosilane having a sterically hindering group such as diphenyldichlorosilane. Therefore, in order to obtain a silicone resin without causing gelation, there are restrictions on the types of chlorosilanes that can be used, their compounding amounts, and the amount of water / alcohol mixture used. There is a problem that the composition, viscosity and alkoxy group content of the resin cannot be freely designed.

Further, there is known a production method for obtaining an alkoxy group-containing silicone resin by re-equilibrating an organopolysiloxane and an alkoxysilane in the presence of a basic catalyst (see JP-A-5-239214). ). However, in this production method, since the organopolysiloxane is produced by hydrolyzing chlorosilane, the above-mentioned problems have not been solved at all. In addition, the alkoxy group-containing silicone resin obtained by re-equilibrating the organopolysiloxane and alkoxysilane under a basic catalyst is a solid or highly viscous substance at room temperature and is used as a raw material for heat-resistant paints. Therefore, there is a disadvantage that it must be dissolved in a large amount of organic solvent. Furthermore, in order to obtain the alkoxy group-containing silicone resin, not only several steps are required in a large amount of organic solvent, but also a large amount of waste water is generated.

As a result of intensive studies conducted by the present inventors in view of the above problems, the composition, viscosity and alkoxy group content of the silicone resin can be easily controlled without using an organic solvent. Moreover, the inventors have found a method for producing a solventless liquid silicone resin containing an alkoxy group that does not generate waste water, and have completed the present invention.

[0005]

Means and Actions for Solving the Problems The present invention provides a compound represented by the general formula (I) R ¹ _n Si (OR ² ) _4-n (I) (wherein R ¹ may be substituted with a halogen atom). 1
A valent hydrocarbon residue, R ² is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 0 to 2), a partial hydrolyzed condensate thereof or a mixture thereof is used as a metal compound catalyst. In the presence of the above, about 0.2 to about 0.5 mole of water is added to 1 mole of the alkoxy group contained in the raw material, and the mixture is reacted under acidic conditions to remove the generated alcohol, and a solventless liquid silicone resin containing an alkoxy group. The present invention provides a method for producing a solventless alkoxy group-containing liquid silicone resin, which comprises:

The solvent-free liquid silicone resin containing an alkoxy group in the present invention means a liquid silicone resin containing an alkoxy group containing no organic solvent. Details of each definition of the general formula (I) are as follows. In the general formula (I), preferred examples of the monovalent hydrocarbon residue represented by R ¹ include a linear or branched alkyl group having 1 to 8 carbon atoms and an aryl group having 6 to 16 carbon atoms. And these monovalent hydrocarbon residues may be substituted with one or more halogen atoms. Specifically, as the alkyl group, methyl, ethyl, n-propyl, i-propyl,
Examples thereof include n-butyl, i-butyl, tert-butyl, n-pentyl, n-hexyl, 1-methylpentyl and 1-methylhexyl groups, and among them, methyl and ethyl groups are more preferable. Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a biphenylyl group, a naphthyl group, an anthryl group, and a phenanthryl group. Among these, a phenyl group and a tolyl group are more preferable. Further, examples of the monovalent hydrocarbon residue substituted with a halogen atom include fluorine-substituted hydrocarbon residues such as 3,3,3-trifluoropropyl and nonafluorobutylethyl groups.

In the general formula (I), when the alkyl group represented by R ² has 5 or more carbon atoms, the hydrolysis rate of the alkoxysilane or its partial hydrolysis-condensation product becomes slow,
The alcohol generated by hydrolysis has a high boiling point and is difficult to remove, which is not preferable. Therefore, the alkyl group represented by R ² preferably has 1 to 4 carbon atoms. The alkyl group having 1 to 4 carbon atoms represented by R ² may be any linear or branched alkyl group,
Specific examples thereof include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl and tert-butyl groups, and among these, methyl, ethyl, n-propyl and n-butyl groups. More preferred are groups.

Specific examples of the alkoxysilane represented by the general formula (I) include, for example, tetramethoxysilane,
Tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane,
Dimethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, Examples thereof include nonafluorobutylethyltrimethoxysilane and nonafluorobutylethyltriethoxysilane, and of these, methyltrimethoxysilane and diphenyldimethoxysilane are more preferable.

The partially hydrolyzed condensate of alkoxysilane can be obtained by a known method, that is, by condensing an alkoxysilane or a mixture thereof under hydrolysis conditions (which is appropriately set depending on the alkoxysilane used). (One kind of partially hydrolyzed condensate of alkoxysilane is called a single partially hydrolyzed condensate, and a partially hydrolyzed condensate of a mixture of alkoxysilanes is called a partially hydrolyzed cocondensate). Preferable examples of the partially hydrolyzed condensate of alkoxysilane include siloxane and polysiloxane having a structure in which these alkoxysilanes are partially hydrolyzed and condensed.

The raw material used in the present invention is an alkoxysilane represented by the general formula (I), a partial hydrolysis-condensation product thereof, or a mixture thereof. Preferred examples of the mixture include a mixture of methyltrimethoxysilane and diphenyldimethoxysilane, a mixture of phenyltrimethoxysilane and dimethyldimethoxysilane, a mixture of phenyltrimethoxysilane and a single partial hydrolysis-condensation product thereof, and dimethyldimethoxysilane. , A mixture of phenyltrimethoxysilane and dimethyldimethoxysilane, and a mixture of phenyltrimethoxysilane and dimethyldimethoxysilane, and a mixture of phenyltrimethoxysilane and dimethyldimethoxysilane. And a mixture of dimethyldimethoxysilane and a mixture of methyltrimethoxysilane, diphenyldimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane. Among these, a mixture of methyltrimethoxysilane and diphenyldimethoxysilane and a mixture of methyltrimethoxysilane and diphenyldimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane are more preferable, and methyltrimethoxysilane and A mixture with diphenyldimethoxysilane is particularly preferred.

The mixing ratio of these mixtures is appropriately set according to the alkoxysilane or the partial hydrolysis-condensation product thereof. For example, in the case of a mixture of methyltrimethoxysilane and diphenyldimethoxysilane, the compounding ratio is 10: 0.2 to 10 (molar ratio) is suitable. The reason is that, for example, when the molar ratio exceeds 10: 0.2 and the amount of methyltrimethoxysilane increases, a solventless alkoxy group-containing liquid silicone resin produced by using the raw material is mixed in the coating composition. In that case, the coating film obtained from the coating composition is brittle, and the adhesion, water resistance and alkali resistance are reduced, while when the molar ratio exceeds 10:10 and the amount of diphenyldimethoxysilane is larger, the raw material When a solventless alkoxy group-containing liquid silicone resin produced by using is blended in the coating composition,
This is because even if the coating composition is applied onto a substrate, the coating film may not be sufficiently cured, and thus the resulting coating film has poor solvent resistance and scratch resistance, which is not preferable.

The raw materials used in the present invention include:
A mixture of methyltrimethoxysilane and diphenyldimethoxysilane having a molar ratio of 10: 0.2 to 10 is more preferable, and a molar ratio of 10: 2 to 8 is particularly preferable. In the present invention, depending on the type of raw material used,
The composition of the solventless alkoxy group-containing liquid silicone resin produced is determined. Therefore, the raw materials to be used are appropriately selected depending on the desired composition of the silicone resin.

As the metal compound catalyst used in the present invention, any metal compound having a function of promoting the hydrolysis reaction and condensation reaction of alkoxysilane or its partial hydrolysis-condensation product can be used. From this viewpoint, a preferable example of the metal compound catalyst is an alkoxide or chelate compound of a metal selected from Al, Ti and Zr, or a mixture thereof, and a partial condensate of these metal compounds can also be used. The partial condensate of the metal compound can be obtained by adding water to the hydrophilic organic solvent containing the metal compound within a range that does not cause precipitation or gelation of the metal compound.

Specifically, the following metal compounds and partial condensates thereof can be used as the metal compound catalyst. Examples of the metal compound catalyst containing Al include, for example, tri-iso-propoxyaluminum, tri-n-propoxyaluminum, tri-sec-butoxyaluminum, tri-n-butoxyaluminum, sec-butoxyaluminum diisopropylate, tri-n-butoxyaluminum. Aluminum-containing metal compounds such as -tert-butoxyaluminum, ethylacetoacetate aluminum diisopropylate, aluminum tris (ethylacetoacetonate), aluminum tris (acetylacetonate) and aluminum monoacetylacetonate bis (ethylacetoacetonate), and The partial condensate etc. are mentioned.

Examples of the metal compound catalyst containing Ti include, for example, tetra-n-propyl titanate and tetra-i.
so-propyl titanate, tetra-n-butyl titanate, tetra-iso-butyl titanate, tetra-sec-butyl titanate, tetra-tert-butyl titanate, tetrakis (2-ethylhexyl) titanate, dipropoxytitanium bis (acetylacetonate), Examples thereof include titanium-containing metal compounds such as titanium tris (ethylacetoacetonate) and titanium tris (acetylacetonate), and partial condensates thereof.

Examples of metal compound catalysts containing Zr include, for example, tetramethoxyzirconium, tetraethoxyzirconium, tetra-iso-propoxyzirconium, tetra-n-propoxyzirconium, tetra-iso.
Examples include zirconium-containing metal compounds such as -butoxyzirconium, tetra-n-butoxyzirconium, tetra-sec-butoxyzirconium, tetrakis (acetylacetone) zirconium and tetrakis (ethylacetoacetate) zirconium, and partial condensates thereof.

These metal compound catalysts act as a reaction accelerator between the alkoxysilane or its partial hydrolysis-condensation product and water, and are, for example, a mixture of methyltrimethoxysilane and diphenyldimethoxysilane having a large difference in hydrolysis rate. Even when is used as a raw material, a cohydrolysis reaction can be caused. The amount of these metal compound catalysts added is less than 100 ppm with respect to the raw materials used,
A solventless alkoxy group-containing liquid silicone resin produced using a metal compound catalyst in an amount that does not allow the reaction between water and the raw materials to be sufficiently promoted and the monomer remains in the reaction product. When it is added to the composition, the coating film obtained from the coating composition is unfavorable because it causes poor curing and lowers the chemical resistance. On the other hand, when the content exceeds 20,000 ppm with respect to the raw material used, when a solventless alkoxy group-containing liquid silicone resin produced using the added amount of the metal compound catalyst is blended in the coating composition, the coating composition The coating film obtained from is not preferable because the water resistance, the chemical resistance and the adhesion are deteriorated. Therefore, the addition amount of the metal compound catalyst is 100 ppm to 2000 ppm with respect to the raw material used.
It is preferably in the range of 0 ppm, particularly preferably in the range of 200 ppm to 10,000 ppm.

In the present invention, it is essential to carry out the hydrolysis reaction and condensation reaction under acidic conditions. The acidic conditions in the present invention mean such an acidity that the reaction is sufficiently promoted and gelation does not occur. Therefore, in order to acidify the reaction solution to the extent that the reaction is sufficiently promoted and gelation does not occur, it is necessary to add an acid as necessary, and the acid acts as a catalyst.

Preferable examples of the acid used in the present invention include mineral acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, and organic acids such as formic acid, acetic acid and paratoluenesulfonic acid. These acids may be added in advance to the water to be added, or may be added to the raw materials used. The amount of these acids added is appropriately set according to the type of acid used, but generally it is appropriate to be within the range of 1 ppm to 20000 ppm, and within the range of 5 ppm to 1000 ppm with respect to the raw material. Is preferred. The reason for this is that if the amount of acid used is less than 1 ppm with respect to the raw material, the reaction will slow down, while if it exceeds 20,000 ppm, the reaction will proceed excessively, resulting in the formation of cyclic or gel-like substances of alkoxysilane or its partial hydrolysis-condensation products. This is because it is not preferable to generate. More specifically, when using a mineral acid, the amount of acid used is 1 ppm to 1000 p
It is preferably in the range of pm, and when an organic acid is used, it is preferably in the range of 100 ppm to 20000 ppm.

In the present invention, about 0.2 mol to about 0.5 mol of water is added per mol of the alkoxy group contained in the raw material. The amount of water added is a total amount taking into consideration the water contained in the acid used. When the amount of water added is less than about 0.2 mol per 1 mol of alkoxy groups contained in the raw material,
Since the content of alkoxy groups in the solvent-free liquid silicone resin containing alkoxy groups produced is large, and only low viscosity and low molecular weight can be obtained, it is not preferable. In addition, when a solventless alkoxy group-containing liquid silicone resin produced by adding less than about 0.2 mol of water to 1 mol of alkoxy groups contained in the raw material is compounded in the coating composition, the curability and coating properties are (For example, adhesion)
It is not preferable because the coating composition is inferior. on the other hand,
If the amount of water added is about 0.5 mol or more, all the alkoxy groups in the raw material will be consumed, and the solventless alkoxy group-containing liquid silicone resin produced does not contain alkoxy groups and is highly viscous or gel-like. It is not preferable because it becomes a thing. Therefore, in the present invention, the addition amount of water is about 0.2 mol to 1 mol of alkoxy groups contained in the raw material.
It is essential that it be in the range of about 0.5 moles, more preferably in the range of about 0.3 moles to about 0.45 moles.

In the present invention, the viscosity and the alkoxy group content of the solventless alkoxy group-containing liquid silicone resin produced are determined by the amount of water used in the reaction. That is, within the above range, as the amount of water used in the reaction increases, the alkoxy group content of the solventless alkoxy group-containing liquid silicone resin produced decreases. Therefore, the amount of water added is appropriately set within the above range depending on the desired viscosity of the silicone resin and the alkoxy group content.

In the present invention, a raw material (alkoxysilane or its partial hydrolysis-condensation product or a mixture thereof) is subjected to a hydrolysis reaction and a condensation reaction, and the generated alcohol is removed to obtain a solvent-free alkoxy group-containing compound. A liquid silicone resin can be obtained. The hydrolysis reaction and condensation reaction of the raw materials are preferably carried out under reflux. The reaction temperature is appropriately in the range of room temperature to reflux temperature, and it is preferable to carry out the reaction at reflux temperature in order to accelerate the reaction. The reflux temperature is appropriately set according to the raw material used and the type of alcohol generated, and is generally a temperature near the boiling point of the generated alcohol. For example, when the generated alcohol is methanol,
Within the range of 65 ° C to about 70 ° C. The reaction time is appropriately about 3 to 20 hours, preferably about 5 to 10 hours.

In the present invention, the generated alcohol may be removed either during the hydrolysis reaction and condensation reaction of the raw materials or after the reaction is completed, but the reaction is sufficiently advanced. If the alcohol is started to be removed when it is not present, the water used in the reaction may be removed, and it is not preferable because the silanol groups remain in the silicone resin produced, so the reaction proceeded sufficiently. After that, it is preferable to remove the generated alcohol. Therefore, the timing of removing the generated alcohol is determined by measuring the progress of the reaction over time.
As a method for determining the progress of the reaction, there are measurement of the molecular weight of the reaction product and measurement of the amount of alcohol generated,
The progress of the reaction is preferably determined by measuring the molecular weight of the reaction product. It can be confirmed that the hydrolysis reaction and the condensation reaction of the raw materials have proceeded sufficiently by the fact that the molecular weight of the reaction product has a substantially constant value and is close to the molecular weight of the silicone resin to be produced. Further, the completion of the reaction can be confirmed by the fact that the molecular weight of the reaction product becomes the molecular weight of the silicone resin to be produced and the molecular weight does not increase any more. As the molecular weight measuring method, for example, a standard polystyrene conversion method by gel permeation chromatography can be applied.

In the present invention, the method for removing alcohol may be atmospheric pressure or reduced pressure. The amount of alcohol generated in the reaction is twice the molar amount of water used in the reaction in calculation. Therefore, the end point of alcohol removal is
It is determined by measuring the amount of alcohol evolved. That is, the alcohol removal may be stopped at the time when the amount of generated alcohol reaches twice the molar amount of water used in the reaction. In the present invention, the removed alcohol can be reused.

After removing the alcohol generated by the reaction as described above, the reaction product (solvent-free liquid silicone resin containing alkoxy group) contains a metal compound catalyst. It does not have to be removed from the reaction product as it has no effect on the properties of the silicone resin (eg water resistance, chemical resistance, etc.). Therefore, the solventless alkoxy group-containing liquid silicone resin produced by the method of the present invention can be used while containing the metal compound catalyst.

In the production method of the present invention, an organic solvent may be added during the hydrolysis reaction and the condensation reaction of the raw materials, but it is necessary to remove the organic solvent when removing the alcohol, which is economical. It cannot be said to be the target. In the present invention, the composition of the solventless alkoxy group-containing liquid silicone resin produced by changing the type of raw material used can be changed, and the solventless produced by changing the amount of water added. The viscosity and alkoxy group content of the alkoxy group-containing liquid silicone resin can be changed.

The solventless alkoxy group-containing liquid silicone resin produced as described above is suitably used for various applications such as electric insulating materials, heat resistant paints, weather resistant paints and resin modifiers. be able to.

[0028]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but it goes without saying that the present invention is not limited to these examples. In the examples, unless otherwise specified, the viscosity is a value at 20 ° C., and MW represents a weight average molecular weight in a standard polystyrene conversion method by gel permeation chromatography.

Example 1 Methyltrimethoxysilane (646 g), diphenyldimethoxysilane (61 g) and aluminum tris (acetylacetonate) (0.7 g) were placed in a reaction vessel, and an aqueous solution containing concentrated sulfuric acid (0.02 g) (93 g) was added. ) Was added and the mixture was heated under reflux for 5 hours. Then, the generated methanol was removed by heating under reduced pressure to obtain a solventless alkoxy group-containing liquid silicone resin (471 g). The viscosity, weight average molecular weight and methoxy group content of the obtained silicone resin were measured. As a result, the viscosity was 35 cp, the MW was 1820, and the methoxy group content was 29.40% (calculated amount 29.3%). Methoxy group content is based on Chemical Analysis Volume 41 (Chem
ical Analysis, Volume 41), pages 154 to 156.

Example 2 In a reaction vessel, methyltrimethoxysilane (510 g), diphenyldimethoxysilane (305 g), aluminum tris (ethylacetoacetonate) (2 g) and concentrated nitric acid (0.1 g) were added.
g) was added, water (93 g) was added, and the mixture was heated under reflux for 8 hours. After that, the generated methanol was removed by heating under reduced pressure to obtain a solventless alkoxy group-containing liquid silicone resin (580 g). The viscosity, weight average molecular weight and methoxy group content of the obtained silicone resin were measured.
As a result, the viscosity was 280 cp, the MW was 1450, and the methoxy group content was 18.3% (calculated amount 18.3%). The methoxy group content was measured in the same manner as in Example 1.

Example 3 In a reaction vessel, methyltrimethoxysilane (510 g), diphenyldimethoxysilane (305 g), aluminum tris (ethylacetoacetonate) (4 g) and concentrated sulfuric acid (0.1 g) were added.
g) was added, water (99 g) was added, and the mixture was heated under reflux for 8 hours. Then, the generated methanol was removed by heating under reduced pressure to obtain a solventless alkoxy group-containing liquid silicone resin (566 g). The viscosity, weight average molecular weight and methoxy group content of the obtained silicone resin were measured.
As a result, the viscosity was 820 cp, the MW was 2100, and the methoxy group content was 15.1% (calculated amount 15.1%). The methoxy group content was measured in the same manner as in Example 1.

[0032]

The method for producing a solvent-free liquid silicone resin containing an alkoxy group according to the present invention changes the composition of the liquid silicone resin containing a solvent-free alkoxy group produced by changing the type of raw material used. By changing the amount of water to be added, the viscosity and the alkoxy group content of the solvent-free liquid silicone resin containing an alkoxy group produced can be changed. Therefore, the composition, viscosity and alkoxy group of the produced silicone resin can be easily controlled. Further, the solventless alkoxy group-containing liquid silicone resin produced by the production method of the present invention is, for example, an electrically insulating material,
It can be suitably used for various applications such as heat resistant paints, weather resistant paints and resin modifiers.

Claims (4)

[Claims] 1. A compound represented by the general formula (I) R ¹ _n Si (OR ² ) _4-n (I) (wherein R ¹ may be substituted with a halogen atom 1
A valent hydrocarbon residue, R ² is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 0 to 2), a partial hydrolyzed condensate thereof or a mixture thereof is used as a metal compound catalyst. In the presence of the above, about 0.2 to about 0.5 mole of water is added to 1 mole of the alkoxy group contained in the raw material, and the mixture is reacted under acidic conditions to remove the generated alcohol, and a solventless liquid silicone resin containing an alkoxy group. A method for producing a solventless alkoxy group-containing liquid silicone resin, which comprises: 2. The solventless alkoxy group-containing liquid silicone resin according to claim 1, wherein the raw material is a mixture of methyltrimethoxysilane and diphenyldimethoxysilane, and the molar ratio thereof is 10: 0.2 to 10. Production method. 3. The metal compound catalyst comprises Al, Ti and Zr.
The method for producing a solventless alkoxy group-containing liquid silicone resin according to claim 1, which is an alkoxide or chelate compound of a metal selected from the above or a mixture thereof. 4. The amount of acid added is 1 ppm to 200 with respect to the raw material.
The method for producing a solventless alkoxy group-containing liquid silicone resin according to claim 1, wherein the amount is 00 ppm.