JP6841166B2 - Method for producing phenylalkoxysilane-treated silica - Google Patents

Description

The present invention relates to a method for producing phenylalkoxysilane treated silica. More specifically, the present invention relates to a method for producing phenylalkoxysilane-treated silica, which can be suitably used as an additive for a resin or the like.

Silica particles are widely used as additives in various materials such as sealing materials, film materials, toner materials, and dental materials. Since the surface of silica particles is hydrophilic, various techniques for hydrophobizing the surface have been developed for the purpose of increasing the affinity with resins and the like. For example, as a method for producing phenylsilane-treated silica, a method of impregnating a solvent containing phenylalkoxysilane and water with silica and then distilling off the solvent containing water is disclosed (see Patent Document 1). As another method, a method of dry-treating a silane compound on silica is disclosed (see Patent Documents 2 and 3).

Japanese Unexamined Patent Publication No. 2005-022915 Japanese Unexamined Patent Publication No. 01-203478 Japanese Unexamined Patent Publication No. 2010-228997

Conventionally, the phenylsilane treatment on the silica surface is usually performed in a wet manner, but when the phenylsilane treatment is performed in a wet manner, the concentration of the phenylsilane treatment liquid recommended by the phenylsilane manufacturer is 0.1 to 2. It is 0%, which is unsuitable for industrial production because it has a problem that the production cost is high because a large amount of solvent is required and the environmental load is high because a large amount of solvent needs to be volatilized. there were. The above Patent Documents 2 and 3 describe a method of dryly performing a silane treatment on the silica surface, resulting in a high degree of hydrophobicity without pretreatment of the silane compound by hydrolysis. However, in the case of phenylalkoxysilane, the desired surface treatment effect (degree of hydrophobicity) cannot be obtained without hydrolysis. Further, when the methods of Patent Documents 2 and 3 are applied to phenylalkoxysilane, self-condensation of phenylsilane occurs due to an increase in the concentration of phenylsilane in the treatment liquid, and bonding to the silica surface is hindered, which is desired. There is a problem that the surface treatment effect (degree of hydrophobicity) cannot be obtained.

The present invention has been made in view of the above situation, and provides a method capable of producing phenylalkoxysilane-treated silica having a lower production cost and environmental load than the conventional one and having a high degree of hydrophobicity. The purpose.

The present inventor has studied various methods for treating the surface of silica with phenylalkoxysilane. As a result, a method including a step of hydrolyzing phenylalkoxysilane and a step of surface-treating silica with a silane compound after the hydrolysis step. Under the condition that the weight of water used in the hydrolysis treatment step, the weight of the organic solvent, the weight of phenylalkoxysilane, and the weight and specific surface area of silica used in the surface treatment step satisfy a predetermined relationship, these water additions are made. By performing the decomposition step and the surface treatment step, it was found that a phenylalkoxysilane-treated silica having a high degree of hydrophobicity can be manufactured while having a lower manufacturing cost and environmental load than the conventional method, and the above-mentioned problems are brilliantly solved. I came up with the idea that it could be solved and completed the present invention.

That is, the present invention is a method for producing silica treated with phenylalkoxysilane, which comprises a step of hydrolyzing phenylalkoxysilane in a solvent containing water and an organic solvent and silane after the hydrolysis. Including a step of surface-treating silica with a compound, the weight of water used in the hydrolysis step is ag, the weight of an organic solvent is bb, and the weight of phenylalkoxysilane is cg. Assuming that the weight is dl and the specific surface area is em ² / g, the hydrolysis step is carried out under the conditions that a / b is 2 to 4 and (c / (a + b)) × 100 is 8 to 42. The surface treatment step is a method for producing a phenylalkoxysilane-treated silica, characterized in that (a + b + c) / (d × e) is carried out under the conditions of 0.01 to 0.03.

The hydrolysis step is preferably carried out under the condition of pH 3-4.

The organic solvent used in the hydrolysis step is preferably methanol.

The method for producing phenylalkoxysilane-treated silica of the present invention uses less water and organic solvent than the conventional phenylsilane-treated method, and has a high degree of hydrophobicity while being a method with low production cost and environmental load. It is a useful production method capable of producing phenylalkoxysilane treated silica.

Hereinafter, an example of the present invention will be specifically described, but the present invention is not limited to the following description, and can be appropriately modified and applied without changing the gist of the present invention.

The method for producing phenylalkoxysilane-treated silica of the present invention includes a step of hydrolyzing phenylalkoxysilane in a solvent containing water and an organic solvent, and a step of surface-treating the silica with a silane compound after hydrolysis.
In the following, these steps will be described.

<Hydrolyzed process>
The hydrolysis step in the method for producing phenylalkoxysilane-treated silica of the present invention is a step of hydrolyzing phenylalkoxysilane in a solvent containing water and an organic solvent, and the weight of water used in the hydrolysis step is ag. Assuming that the weight of the organic solvent is bb and the weight of the phenylalkoxysilane is cg, a / b is 2 to 4, and (c / (a + b)) × 100 is 8 to 42. To do. When the phenylalkoxysilane is hydrolyzed by such a method, the phenylalkoxysilane is sufficiently hydrolyzed with a smaller amount of water or an organic solvent as compared with the conventional wet method, and a part or all of the alkoxy groups are removed. It can be a hydroxyl group.

The weight ratio a / b of water used in the hydrolysis step to the organic solvent may be 2 to 4. Water is required for the hydrolysis reaction, and since phenylalkoxysilane is hydrophobic, an organic solvent is required to make it compatible with water. If the amount is too small, the hydrolysis rate will be slow, but if the weight ratio a / b is 2 to 4, the hydrolysis reaction can proceed at a good rate. a / b is preferably 2 to 3.

The weight ratio of phenylalkoxysilane to the total weight of water and the organic solvent used in the hydrolysis step (c / (a + b)) × 100 may be 8 to 42. If the amount of phenylalkoxysilane is too large with respect to the total weight of water and the organic solvent, the hydrolyzed phenylalkoxysilanes may become close to each other and self-condensate. Self-condensation between hydrolyzed phenylalkoxysilanes can also be effectively suppressed without using a large amount of solvent. (C / (a + b)) × 100 is preferably 8 to 20, and more preferably 10 to 19.

The hydrolysis step is preferably carried out under the condition of pH 3-4. Hydrolysis of phenylalkoxysilane can be promoted in a short time by carrying out under the condition of pH 3 to 4. Further, the self-condensation of phenylalkoxysilane can be effectively suppressed by carrying out under the condition of pH 4 or less. The pH is more preferably 3.5-4. The pH may be appropriately adjusted using an acid or an alkali.

The hydrolysis step is preferably carried out with stirring. By stirring, the phenylalkoxysilane can be hydrolyzed more sufficiently.
The time for performing the hydrolysis step is not particularly limited, but is preferably 20 to 40 minutes. More preferably, it takes 30 to 40 minutes. By setting such a time, hydrolysis can be promoted more sufficiently while suppressing self-condensation of phenylalkoxysilane.

The stirring means in the hydrolysis step is not particularly limited, and examples thereof include stirring with a stirring blade, shaking stirring, stirring with a mixer, and stirring with a stirrer.

The temperature at which the hydrolysis step is carried out is not particularly limited, but it is preferably carried out at 10 to 60 ° C. More preferably, it is 20 to 60 ° C.

<Surface treatment process>
The surface treatment step in the method for producing phenylalkoxysilane-treated silica of the present invention is a step of surface-treating silica with a silane compound after hydrolysis, in which the weight of water used in the hydrolysis step is ag and the weight of an organic solvent. Is bg, the weight of phenylalkoxysilane is cg, the weight of silica used in the surface treatment step is dg, and the specific surface area is em ² / g, then (a + b + c) / (d × e) is 0.01 to 0. It is characterized in that it is performed under the condition of .03. The surface treatment step is a step of surface-treating silica with a dispersion liquid containing the hydrolyzed silane compound, water and an organic solvent obtained in the hydrolysis step.
If the amount of the phenylalkoxysilane hydrolyzed solution containing the hydrolyzed silane compound, water and an organic solvent is too small with respect to silica, the hydrolyzed phenylalkoxysilane does not blend into the entire silica particles, and uniform surface treatment cannot be performed. If there is too much phenylalkoxysilane hydrolyzed solution, the silica particles will become phenylalkoxy after adding the phenylalkoxysilane hydrolyzed solution to the silica particles (especially when the standing time is provided, which will be described later). It may settle in the silane hydrolyzed solution and the surface treatment may not be uniform. By performing the surface treatment step under the condition that (a + b + c) / (d × e) is 0.01 to 0.03 in consideration of the weight of silica to be surface-treated and its specific surface area, a large amount of phenylalkoxysilane-containing solution is produced. The silica surface can be sufficiently hydrophobized without being used in.
(A + b + c) / (d × e) may be 0.01 to 0.03, but is preferably 0.01 to 0.02.

In the surface treatment step, it is preferable to add the hydrolyzed silane compound to the silica and then stir. By stirring, the reaction between the silanol group of the hydrolyzed silane compound and the silanol group on the silica surface can be sufficiently advanced to further increase the surface treatment degree (hydrophobicity) of the silica.
The stirring time is not particularly limited, but is preferably 20 to 60 minutes. More preferably, it takes 30 to 60 minutes.
Examples of the stirring means include a blender and a ball mill.

Further, in the surface treatment step, it is preferable to provide a time for allowing the hydrolyzed silane compound to stand after being added to the silica.
When a solution containing the hydrolyzed silane compound, water, and an organic solvent is added to silica, the phenylalkoxysilane hydrolyzate is impregnated between the silica particles, and the silane compound and the silica particles are chemically bonded to form a hydrophobic silica surface. Be made. By providing the standing time, the formation of chemical bonds between the silane compound and the silica particles can proceed more sufficiently, and the degree of surface treatment (degree of hydrophobicity) of silica can be increased. More preferably, the hydrolyzed silane compound is added to the silica, stirred, and then allowed to stand for a period of time.
Considering increasing the surface treatment degree (hydrophobicity degree) of silica and productivity, the standing time is preferably 5 to 40 hours. When the standing time is provided, it is preferable to keep the standing still in a closed state in order to suppress the volatilization of the organic solvent and water.

The temperature at which the surface treatment step is performed is not particularly limited, but is preferably 10 to 50 ° C. More preferably, it is 20 to 40 ° C.

In the surface treatment step, as long as the silane compound obtained by hydrolyzing phenylalkoxysilane is used as the surface treatment agent, other surface treatment agents may be further used in combination, but the silane compound and the other surface treatment agent are used in combination. The proportion of the other surface treatment agent in the total 100% by mass is preferably 50% by mass or less. More preferably 30% by mass or less, further preferably 10% by mass or less, particularly preferably 1% by mass or less, and most preferably 0% by mass, that is, obtained by hydrolyzing phenylalkoxysilane as a surface treatment agent. It is to use only the silane compound which is obtained.
As the other surface treatment agent, one kind or two or more kinds can be used.

Further, in the surface treatment step, inorganic oxide particles other than the silica particles may be used, if necessary. When inorganic oxide particles other than silica particles are used, surface-treated silicon-containing composite inorganic particles are obtained.
The other inorganic oxide particles are not particularly limited, but for example, those containing elements of Group II to VI of the Periodic Table of the Elements are preferable, and those containing elements of Groups III to IV of the Periodic Table of the Elements are more preferable. Of these, Al, Ti and / or Zr are preferable. The amount of the other inorganic oxide particles used may be appropriately set according to the intended use, and for example, the total amount of the raw material inorganic oxide particles (total amount of the silica particles and the other inorganic oxide particles) is 100% by mass. On the other hand, it is preferably 50% by mass or less. More preferably 30% by mass or less, further preferably 10% by mass or less, particularly preferably 1% by mass or less, most preferably 0% by mass, that is, only silica particles are used.
As the other inorganic oxide particles, one kind or two or more kinds can be used.

<Other processes>
The method for producing phenylalkoxysilane-treated silica of the present invention preferably includes a step of drying the silica obtained in the surface treatment step.
The temperature and time of the drying step are not particularly limited as long as the silica obtained in the surface treatment step is sufficiently dried, but the temperature of the drying step is preferably 100 to 200 ° C. More preferably, it is 120 to 200 ° C.
The time of the drying step is preferably 1 to 10 hours. More preferably, it is 2 to 5 hours.

The method for producing a phenylalkoxysilane-treated silica of the present invention may further include other steps in addition to the hydrolysis step, the surface treatment step and the drying step.

<Phenylalkoxysilane>
The phenylalkoxysilane used in the present invention may be a compound containing a phenyl group and an alkoxy group and having a Si—O bond. Among them, the following general formula (1):
X _m- Si- (OR) _4-m (1)
(In the formula, X represents a phenyl group which may have a substituent. R represents an alkyl group having 1 to 5 carbon atoms. M represents an integer of 1 to 3). Compounds are preferred.

In the above general formula (1), X represents a phenyl group which may have a substituent. Examples of the substituent include a hydroxyl group and a halogen atom. Above all, from the viewpoint of enhancing the dispersion stability of the phenylalkoxysilane-treated silica obtained by the production method of the present invention in a resin or the like, an amino group-free phenyl group, that is, an amino group-free phenyl group is preferable. More preferably, it does not have a substituent, that is, it is an unsubstituted phenyl group.

R represents an alkyl group having 1 to 5 carbon atoms. It may be linear, branched or cyclic, but is preferably a linear or branched alkyl group. The number of carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 to 2.

m represents an integer of 1 to 3. It is preferably 1 or 2, and more preferably 1. That is, phenyltrialkoxysilane is more preferable as the compound represented by the general formula (1).

Specifically, for example, phenyltrimethoxysilane and phenyltriethoxysilane are suitable as the phenylalkoxysilane.
In the production method of the present invention, one type of phenylalkoxysilane may be used, or two or more types may be used.

<Organic solvent>
The organic solvent used in the hydrolysis step is not particularly limited as long as it can hydrolyze phenylalkoxysilane, but it is preferable to use either or both of methanol and ethanol. By using such a lower alcohol, hydrolysis is facilitated. More preferably, it is methanol.

<Silica>
The silica used in the present invention may be either silicic anhydride or hydrous silicic acid. For example, as silicic anhydride, silica (fumed silica) produced by a dry method (flame combustion method or the like), quartz, tridymite, cristobalite, coesite, tridymite, quartz glass and the like can be mentioned. Examples of the hydrous silicic acid include so-called amorphous silica gel obtained by gelling and drying silica hydrosol, colloidal silica, silicate oligomer, micelle template type silica and the like. Of these, amorphous silica is more preferable.
As the silica, one type may be used, or two or more types may be used.

The silica used in the present invention preferably has a specific surface area of ² to 15 m 2 / g. More preferably, those wherein 2 to 10 m ² / g, more preferably those wherein 2~7m ² / g.

In the present specification, the specific surface area means the BET specific surface area (also referred to as SSA) obtained by the BET method. The BET method is a gas adsorption method in which gas particles such as nitrogen are adsorbed on solid particles and the specific surface area is measured from the adsorbed amount. Based on the relationship between the pressure P and the adsorption amount V, the single molecule adsorption amount VM is determined by the BET formula. By finding it, the specific surface area is determined. A detailed method for measuring the specific surface area in the present specification will be described in Examples described later.

The silica used in the present invention is in the form of particles, and the shape of the particles is not particularly limited, but the long-term stability of the dispersion obtained by dispersing the phenylalkoxysilane-treated silica obtained by the production method of the present invention in a solvent or resin is improved. From the viewpoint of the above, it is preferable that the shape is substantially spherical (spherical or close to spherical).
The particle shape can be observed with a scanning electron microscope or the like.

<Phenylalkoxysilane treated silica>
The phenylalkoxysilane-treated silica obtained by the method for producing a phenylalkoxysilane-treated silica of the present invention preferably has a degree of hydrophobicity of 15 to 35%. When the degree of hydrophobization is 15 to 35%, the affinity with a solvent having a relative permittivity of 5 to 30 is improved. In the semiconductor field, a resin that is compatible with a solvent having a relative permittivity of 5 to 30 is used. Therefore, a phenylalkoxysilane-treated silica having a hydrophobicity of 15 to 35% can be used as a resin used in the semiconductor field. It can be suitably used as an additive.
The degree of hydrophobization of the phenylalkoxysilane-treated silica is more preferably 20 to 35%.

Examples of the solvent having a relative permittivity of 5 to 30 include cyclohexanone (relative permittivity: 18.3 (20 ° C)), methyl ethyl permittivity (relative permittivity: 18.5 (20 ° C)), and propylene glycol monomethyl ether acetate. (Relative permittivity: 8.3), propylene glycol monomethyl ether (relative permittivity: 12.3), ethanol (relative permittivity: 24.3 (25 ° C)), n-propyl alcohol (relative permittivity: 20. 1 (25 ° C)), benzyl alcohol (relative permittivity: 13.1 (20 ° C)), phenol (relative permittivity: 9.78 (60 ° C)), m-cresol (relative permittivity: 11.8 (relative permittivity)) (25 ° C))), acetone (relative permittivity: 20.7 (25 ° C)), tetrahydrofuran (relative permittivity: 7.6) and the like.

Examples of the resin having good compatibility with a solvent having a relative permittivity of 5 to 30 include acrylic resin and epoxy resin.

The phenylalkoxysilane-treated silica obtained by the method for producing phenylalkoxysilane-treated silica of the present invention has excellent dispersion stability in a resin, and is therefore used in various applications such as sealing materials, film materials, toner materials, and dental materials. It can be suitably used as an additive for the resin to be used.

Examples will be given below to explain the present invention in detail, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "mass% (% by weight)" and "parts" means "parts by mass (parts by weight)".

Example 1
(Preparation of phenyltrimethoxysilane hydrolyzate)
After adding 6 g of methanol to 14 g of water, the pH was adjusted to 3.8 by keeping the temperature at 25 ° C. and adding acetic acid. 2 g of phenyltrimethoxysilane (KBM-103 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to a pH 3.8 water and methanol solution maintained at 25 ° C., and the mixture was stirred with a stirrer for 35 minutes to prepare a phenyltrimethoxysilane hydrolyzate. Prepared.

(Surface treatment of silica particles)
^{200 g of silica having a specific surface area of 6.8 m 2} / g and a phenyltrimethoxysilane hydrolyzate were put into a cylindrical wide-mouthed bottle having an internal volume of 1 L and a height of 170 mm, the lid of the wide-mouthed bottle was closed, and the bottle was turned upside down 100 times. The wide-mouthed bottle was allowed to stand for 7 hours with the lid closed. After standing, silica was transferred from a wide-mouthed bottle to a stainless steel vat and heated in a dryer set at 130 ° C. for 3 hours to obtain surface-treated silica. The degree of hydrophobization of the obtained surface-treated silica was 19%. The specific surface area of silica and the degree of hydrophobicity of surface-treated silica were measured or calculated by the following methods.
[Measuring method of specific surface area of silica (BET specific surface area)]
The BET specific surface area was measured by heat-treating the sample in a nitrogen atmosphere at 200 ° C. for 40 minutes and using GEMINI VII2390 manufactured by Micromeritics.
[Hydrophobicity of surface-treated silica]
Put 50 mL of ion-exchanged water in a 200 mL beaker, then put 0.200 g of surface-treated silica, and while stirring with a stirrer, add methanol using a burette and drop until the surface-treated silica floating on the liquid surface completely sinks. The amount of methanol was read and the degree of hydrophobicity was calculated from the following formula.
Hydrophobicity (%) = {titration (mL) / [titration (mL) + 50 (mL)]} x 100

Examples 2-8, Comparative Examples 1-6
Example 1 except that the amount of water, organic solvent, phenylalkoxysilane used, the amount and specific surface area of silica, and the stirring time at the time of preparing the hydrolyzed solution of phenylalkoxysilane were changed as shown in Table 1. Surface-treated silica was produced in the same manner. Table 1 also shows the degree of hydrophobization of the obtained surface-treated silica.

From the results in Table 1, by producing the surface-treated silica by a manufacturing method that satisfies the requirements of the manufacturing method of the phenylalkoxysilane-treated silica of the present invention, the surface treatment can be sufficiently performed without using a large amount of water or an organic solvent. It was confirmed that silica having a high degree of hydrophobicity can be obtained.

Claims (3)

A method for producing silica treated with phenylalkoxysilane.
The production method includes a step of hydrolyzing phenylalkoxysilane in a solvent containing water and an organic solvent, and a step of surface-treating silica with the hydrolyzed silane compound.
The weight of water used in the hydrolysis step is ag, the weight of organic solvent is bg, the weight of phenylalkoxysilane is cg, the weight of silica used in the surface treatment step is dg, and the specific surface area is em ² / g. Then,
The hydrolysis step is carried out under the conditions that a / b is 2 to 4 and (c / (a + b)) × 100 is 8 to 42.
The method for producing phenylalkoxysilane-treated silica, wherein the surface treatment step is carried out under the condition that (a + b + c) / (d × e) is 0.01 to 0.03. The method for producing phenylalkoxysilane-treated silica according to claim 1, wherein the hydrolysis step is carried out under conditions of pH 3 to 4. The method for producing phenylalkoxysilane-treated silica according to claim 1 or 2, wherein the organic solvent used in the hydrolysis step is methanol.