JP2017197416A - Silica particle dispersion and surface-treated silica particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silica particle dispersion that is easy to store and transport, and can maintain a dispersion state stably for a long time and a method of producing the same, a surface-treated silica particle suitable for such a dispersion and a method for producing the same, and a silica-containing resin composition and a sealing material prepared with a surface-treated silica particle.SOLUTION: A silica particle dispersion comprises a surface-treated silica particle and a solvent, wherein the surface-treated silica particle is surface-treated with phenyl alkoxysilane and has a hydrophobicity of 15-35%.SELECTED DRAWING: None

Description

The present invention relates to a silica particle dispersion and surface-treated silica particles. More specifically, the present invention relates to a silica-containing resin composition, a surface-treated silica particle, and a production method thereof, as well as a silica-containing resin composition and a sealing material.

Silica particles are widely used as additives in various materials such as sealing materials, film materials, toner materials, and dental materials. However, since the surface of the silica particles is usually hydrophilic, various techniques for hydrophobizing the surface have been developed for the purpose of increasing the affinity with a resin or the like (see, for example, Patent Documents 1 to 3).

JP 2006-096641 A JP 2014-028756 A JP 2010-228997 A

Conventionally, a liquid material is mainly used as a sealing material, and means for mounting by injection sealing with a capillary flow has been adopted. However, the liquid sealing material has a problem that it is difficult to control the injection amount and the shape and thickness after curing are not stable, and recently, a film-like sealing material has been newly developed. In order to obtain a film-shaped sealing material using silica particles, for example, a process of dispersing silica particles in a solvent and mixing it with a resin to form a film is required. It has been found that conventional silica particles have insufficient dispersion stability in a solvent and settle and separate before mixing with a resin. In this case, there are problems in terms of work efficiency, transportation, and storage.

The present invention has been made in view of the above situation, and an object of the present invention is to provide a silica particle dispersion that can be easily stored and transported and can stably maintain a dispersed state for a long period of time, and a method for producing the same. Another object of the present invention is to provide surface-treated silica particles suitable for such a dispersion, a method for producing the same, and a silica-containing resin composition and a sealing material using the surface-treated silica particles.

The present inventor has conducted intensive studies on a dispersion containing silica particles and a solvent. As the silica particles, surface-treated silica particles that have been subjected to surface treatment with phenylalkoxysilane and have a degree of hydrophobicity of 15 to 35%. If the dispersion containing this and a solvent is used, the dispersion state can be stably maintained for a long period of time, storage and transportation can be facilitated, and the re-stirring step before using the dispersion can be simplified or omitted. I found it. In addition, in order to obtain the surface-treated silica particles that give this dispersion, if a production method including a step of heating the silica particles and the surface treatment agent to a predetermined temperature after mixing, the surface-treated silica particles are easily and simply applied. As a result, it was found that the above problems could be solved brilliantly, and the present invention was completed.

That is, the present invention is a silica particle dispersion containing surface-treated silica particles and a solvent, wherein the surface-treated silica particles are surface-treated with phenylalkoxysilane and have a hydrophobicity of 15 to 35%. It is a particle dispersion.

The surface-treated silica particles preferably have a vaporized water content at 150 to 210 ° C. of 600 ppm or less. In the surface-treated silica particles whose vaporized water content is within this range, the bond between the silica particle surface and phenylalkoxysilane is sufficiently strong, so that the natural sedimentation of the particles in the dispersion is further suppressed, and the dispersion Long-term stability of the body is further improved.

The solvent preferably has a relative dielectric constant of 5-30. Since such a solvent is excellent in affinity with the surface-treated silica particles, the long-term stability of the silica particle dispersion becomes better, and it becomes more useful for sealing material applications.

The surface-treated silica particles preferably have an average SEM diameter of 0.05 to 0.20 μm. Thereby, the natural sedimentation of the particles is further suppressed, and the long-term stability is further improved.

The surface-treated silica particles in the dispersion are preferably 30 to 70% by mass. Thereby, for example, when used for a film-like sealing material, the amount of solvent volatilized during the production of the sealing material is reduced, the production efficiency is improved, and the distance between the silica particles in the dispersion is moderate. Thus, the aggregation and sedimentation of the silica particles are further suppressed, and the viscosity of the dispersion is improved, so that the workability when used in various applications is improved.

The silica particle dispersion preferably has a sedimentation rate after standing for 1000 hours of 10% or less. In such a form, the long-term stability is excellent, and thus the effects of the present invention can be more fully exhibited.

The present invention is also a method for producing the above silica particle dispersion, wherein the production method comprises a step (I) of mixing silica particles and a surface treatment agent, and a mixture obtained in 120 (1). It includes a step (II) of heating to ˜250 ° C. and a step (III) of dispersing in a solvent, and the surface treatment agent is also a method for producing a silica particle dispersion containing phenylalkoxysilane.

The present invention is also a surface-treated silica particle which is surface-treated with phenylalkoxysilane and has a hydrophobicity of 15 to 35%.

The present invention is also a method for producing the surface-treated silica particles, wherein the production method comprises a step (I) of mixing the silica particles and the surface treatment agent, and a mixture obtained in the step (I) of 120. And the step (II) of heating to ˜250 ° C., and the surface treatment agent is also a method for producing surface-treated silica particles containing phenylalkoxysilane.

The present invention is also a silica-containing resin composition containing the silica particle dispersion and a resin component. The silica-containing resin composition is preferably a film-form sealing material resin composition.

The present invention is also a sealing material including the surface-treated silica particles and a resin component.

Since the silica particle dispersion of the present invention can stably maintain a dispersed state for a long period of time, it can be easily stored and transported, and the re-stirring step before use can be simplified or omitted. Therefore, in addition to being particularly useful as a raw material for a film-like sealing material, it is also useful for various uses such as sealing materials of other shapes, film materials, toner materials, and dental materials. The surface-treated silica particles of the present invention can provide such a dispersion having excellent long-term stability, and a silica-containing resin composition and a sealing material containing the same can be used for manufacturing electrical / electronic components such as semiconductors. In order to be able to simplify and to stably exhibit high performance, it makes a great contribution to the industry.

Hereinafter, an example of the present invention will be specifically described. However, the present invention is not limited to the following description, and can be applied with appropriate modifications within a range not changing the gist of the present invention.

1. Silica particle dispersion First, the silica particle dispersion which is the first embodiment of the present invention will be described.
The silica particle dispersion of the present invention (hereinafter also referred to as “dispersion”) includes surface-treated silica particles and a solvent. If necessary, other components may be contained, and one or two or more of each component may be used.
Hereinafter, each component contained in the silica particle dispersion will be described.

-Surface treated silica particles-
The surface-treated silica particles mean particles obtained by treating (modifying) part or all of the surface of the silica particles. In particular, in the present invention, the surface-treated silica particles have a degree of hydrophobicity of 15 to 35% and are surface-treated with phenylalkoxysilane, that is, in other words, at least a part of hydroxyl groups on the surface of the silica particles is phenylalkoxy. Particles substituted with a silane-derived group and having a degree of hydrophobicity within the range are used.

Usually, the silica surface is hydrophilic, but the surface-treated silica particles are given moderate hydrophobicity due to the steric hindrance and hydrophobicity of the phenyl group, and the silica particle surface and phenylalkoxysilane Since the bond is sufficiently strong, it is sufficiently suppressed that the bond is broken with time, so that the dispersed state of the particles can be stably maintained in the solvent. Therefore, the silica particle dispersion has excellent long-term stability.
In Examples of Patent Documents 1 to 3, the silica particles are surface-treated with aminopropyltriethoxysilane, HMDS (hexamethyldisilazane), or methyltrimethoxysilane. However, these surface treatment agents do not have a phenyl group, unlike phenylalkoxysilane, and therefore cannot impart steric hindrance and hydrophobicity due to the phenyl group to silica particles (for example, test examples described later). 13, 14). Therefore, the effect of the present invention for stably maintaining the dispersed state of the particles in the solvent cannot be exhibited.

The phenylalkoxysilane may be any compound containing a phenyl group and an alkoxy group and having a Si—O bond. Among these, the following general formula (1):
_{X m -Si- (OR) 4-} m (1)
(Wherein X represents an optionally substituted phenyl group, R represents an alkyl group having 1 to 5 carbon atoms, and m represents an integer of 1 to 3). Are preferred.

In the 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. Among these, from the viewpoint of increasing the stability of the dispersion, an amino group is not contained, that is, an amino group-free phenyl group is preferred. More preferably, it has no substituent, that is, an unsubstituted phenyl group.

R represents an alkyl group having 1 to 5 carbon atoms. Although it may be any of linear, branched or cyclic, it is preferably a linear or branched alkyl group. Carbon number becomes like this. Preferably it is 1-4, More preferably, it is 1-3, More preferably, it is 1-2.

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

Specific examples of the phenylalkoxysilane include phenyltrimethoxysilane and phenyltriethoxysilane.

The degree of hydrophobicity of the surface-treated silica particles is 15 to 35%. When the degree of hydrophobicity is within this range, for example, the affinity with a solvent having a relative dielectric constant of 5 to 30 described later is improved, and the long-term stability of the silica particle dispersion becomes better. It is preferably 18% or more, more preferably 20% or more, and preferably 33% or less.
In the present specification, the degree of hydrophobicity is determined according to the measurement method described in the examples described later.

The surface-treated silica particles preferably have a water vapor content at 150 to 210 ° C. of 600 ppm or less. In the surface-treated silica particles whose vaporized water content is within this range, the bond between the silica particle surface and phenylalkoxysilane is sufficiently strong, so that the natural sedimentation of the particles in the dispersion is further suppressed, and the dispersion Long-term stability of the body is further improved. More preferably, it is 580 ppm or less, More preferably, it is 550 ppm or less. The lower limit is not particularly limited as long as it is 0 ppm or more.
In the present specification, the amount of water vaporized is determined according to the method described in Examples described later.

The specific surface area of the surface-treated silica particles is preferably ^{20 to} 60 m ² / g. When the specific surface area is within this range, the natural precipitation of the silica particles is further suppressed, and the long-term stability of the dispersion is improved. In addition, since the specific surface area is 60 m ² / g or less, the self-aggregation force of the silica particles is more sufficiently reduced, and the particles can be dispersed in a solvent with a weak share. Contribute to. More preferably ^21m 2 / g or more, and more preferably not more than ^55m 2 / g.

In the present specification, the specific surface area means a 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. From the relationship between the pressure P and the adsorption amount V, the monomolecular adsorption amount VM is determined by the BET equation. By determining, 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 surface-treated silica particles preferably have an average SEM diameter of 0.05 to 0.20 μm. Thereby, the natural sedimentation of the particles is further suppressed, and the long-term stability is further improved. More preferably, it is 0.06 micrometer or more, More preferably, it is 0.07 micrometer or more, Most preferably, it is 0.08 micrometer or more, More preferably, it is 0.18 micrometer or less, More preferably, it is 0.16 micrometer or less.
In the present specification, the average SEM diameter is determined by the method described in Examples described later.

The surface-treated silica particles also preferably have a CV value of 0.15 or less. Since such particles have a uniform particle diameter and few coarse particles, the sedimentation rate when the silica particle dispersion is made is sufficiently slow, so that a silica particle dispersion excellent in long-term stability can be obtained. . More preferably, it is 0.1 or less, More preferably, it is 0.09 or less. The lower limit is not particularly limited as long as it is 0 or more.
In the present specification, the CV value means an index of the spread of the particle size distribution, that is, the variation of the particle diameter, and is determined by the method described in Examples described later.

The shape of the surface-treated silica particles is not particularly limited, but from the viewpoint of improving the long-term stability of the silica particle dispersion, the surface-treated silica particles are preferably substantially spherical (spherical or nearly spherical).
The particle shape can be observed with a scanning electron microscope or the like.

-Solvent-
The solvent preferably has a relative dielectric constant of 5 to 30. That is, it is preferable to use a compound having a relative dielectric constant of 5 to 30 as the solvent. Since such a solvent is excellent in affinity with the above-mentioned surface-treated silica particles, the long-term stability of the silica particle dispersion becomes better, and is further useful for sealing material applications. More preferably, it is a solvent having a relative dielectric constant of 8 to 25.
In addition, although 1 type (s) or 2 or more types can be used for a solvent, when using 2 or more types, it is preferable that the relative dielectric constant as the whole mixed solvent exists in the said range.

Although it does not specifically limit as a solvent whose dielectric constant is 5-30, For example, cyclohexanone (relative dielectric constant: 18.3 (20 degreeC)), methyl ethyl ketone (relative dielectric constant: 18.5 (20 degreeC)), 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) Ratio: 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 (25 ° C.)), acetone (relative permittivity: 20.7 (25 ° C.)), tetrahydrofuran (relative permittivity: 7.6) and the like are preferable. Among the solvents having a relative dielectric constant of 5 to 30, cyclohexanone, methyl ethyl ketone, propylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether are particularly preferable because they are easy to handle and can be suitably applied to the resin composition. .

For reference, other typical solvents such as heptane, cyclohexane, benzene, toluene, p-xylene, methanol, glycerin, diethyl ether, propylene glycol, dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, water The relative dielectric constants are 1.924 (20 ° C.), 2.023 (20 ° C.), 2.284 (20 ° C.), 2.379 (25 ° C.), 2.27 (20 ° C.), 32.6 (respectively). 25 ° C), 42.5 (25 ° C), 4.335 (20 ° C), 32, 45-49, 32, 37, 38, 80.1 (20 ° C).

In the silica particle dispersion of the present invention, the surface-treated silica particle concentration (solid content concentration) may be appropriately set depending on the application to be used and the like, for example, 30 to 70 mass with respect to 100 mass% of the silica particle dispersion. % Is preferred. When it is 30% by mass or more, for example, when used for a film-like sealing material, the amount of solvent volatilized during the production of the sealing material is reduced, and the production efficiency is improved. Further, when it is 70% by mass or less, the distance between the silica particles in the dispersion becomes appropriate, the aggregation and sedimentation of the silica particles are further suppressed, and the viscosity of the dispersion becomes favorable, and various uses. The workability when using the product is improved. More preferably, it is 40 mass% or more, More preferably, it is 50 mass% or more, More preferably, it is 65 mass% or less, More preferably, it is 60 mass% or less.

The silica particle dispersion preferably has a sedimentation rate after standing for 1000 hours of 10% or less. In such a form, since it is excellent in long-term stability, it becomes possible to exhibit the effect of this invention more fully. More preferably, it is 8% or less, More preferably, it is 6% or less, Especially preferably, it is 5% or less, Most preferably, it is 4.5% or less.
In the present specification, the sedimentation rate after standing for 1000 hours means the ratio of the silica particles settled after preparing the dispersion and then standing at 24 to 26 ° C. for 1000 hours. Specifically, it is determined according to the measurement method described in the examples described later.

<Manufacturing method>
In order to obtain the silica particle dispersion of the present invention, for example, the step (I) of mixing silica particles (also referred to as “raw material silica particles”) and a surface treatment agent, and the mixture obtained in the step (I) is 120. It is preferable to employ a production method including a step (II) of heating to ˜250 ° C. and a step (III) of dispersing in a solvent, and the surface treatment agent includes phenylalkoxysilane. According to this production method, the dispersion of the present invention can be obtained easily and simply. If necessary, one or more other steps may be further included, and the other steps are not particularly limited.
Hereinafter, each step will be further described.

-Step (I)-
Step (I) is a step of mixing the raw material silica particles and the surface treatment agent. Among them, a step of mixing raw material silica particles and a surface treatment agent in the presence of a dispersion medium, that is, a step of preparing a slurry (also referred to as “suspension”) containing silica particles, a surface treatment agent and a dispersion medium. It is preferable that The production method is not particularly limited, and it is preferable to stir so that the raw materials are uniformly mixed. The order of adding and mixing the raw materials is not particularly limited. Although the temperature at the time of slurry preparation is not specifically limited, For example, it is preferable to set it as 5-60 degreeC from a viewpoint of making it easy to hydrolyze a work surface or phenylalkoxysilane. More preferably, it is 30-60 degreeC, More preferably, it is 40-60 degreeC.
Each raw material can be used alone or in combination of two or more.

Hereinafter, the raw materials used will be further described.
The raw material silica particles may be either anhydrous silicic acid or hydrous silicic acid. Examples of silicic anhydride include silica (fumed silica) produced by a dry method (flame combustion method, etc.), quartz, tridymite, cristobalite, corsite, stishovite, quartz glass, and the like. 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. Among these, amorphous silica is more preferable.

The raw material silica particles preferably have an average SEM diameter of 0.05 to 0.19 μm. Thereby, the surface treatment of the step (II) is more suitably performed. In addition, since the average SEM diameter of the surface-treated silica particles obtained through the step (II) is in a suitable range, the long-term stability of the silica particle dispersion is improved as described above, and the cost reduction and production required for the dispersion equipment are improved. Can contribute to the improvement of performance. More preferably, it is 0.06 micrometer or more, More preferably, it is 0.07 micrometer or more, More preferably, it is 0.18 micrometer or less, More preferably, it is 0.16 micrometer or less.
In the present specification, the average SEM diameter is determined by the method described in Examples described later.

The shape of the raw silica particles is not particularly limited, but from the viewpoint of improving the long-term stability of the silica particle dispersion, it is preferably substantially spherical (spherical or nearly spherical).
The particle shape can be observed with a scanning electron microscope or the like.

The specific surface area of the raw silica particles is not particularly limited, but is preferably 20 to 50 m ² / g, for example. Thereby, since the specific surface area of the surface-treated silica particles obtained through the step (II) is in a suitable range, the long-term stability of the silica particle dispersion is improved as described above, and the cost reduction and production required for the dispersion equipment are improved. Can contribute to the improvement of performance. In particular, when the specific surface area of the raw silica particles is 50 m ² / g or less, the long-term stability of the silica particle dispersion is remarkably improved. The lower limit value of the specific surface area of the raw silica particles is more preferably 21 m ² / g or more, and the upper limit value is more preferably 47 m ² / g or less.

The surface treatment agent includes at least phenylalkoxysilane. Thereby, due to the steric hindrance and hydrophobicity of the phenyl group, moderate hydrophobicity is imparted to the surface-treated silica particles obtained through the step (II), so that the long-term stability of the resulting dispersion is further improved. It will be excellent. The phenylalkoxysilane is as described above.

As the surface treatment agent, other surface treatment agents other than phenylalkoxysilane may be used in combination, but from the viewpoint of improving the long-term stability of the resulting silica particle dispersion, the amount of other surface treatment agent used is: It is preferable to set it to 50 mass% or less in 100 mass% of the total amount of all surface treating agents. More preferably, it is 30 mass% or less, More preferably, it is 10 mass% or less, Most preferably, it is 1 mass% or less. That is, it is particularly preferable to use substantially only phenylalkoxysilane as the surface treatment agent.

The amount of the surface treatment agent used is preferably, for example, 1 to 30 parts by mass with respect to 100 parts by mass of the raw material silica particles. Thereby, the surface treatment of the silica particles in the step (II) is performed more efficiently. More preferably, it is 2 mass parts or more, More preferably, it is 3 mass parts or more, More preferably, it is 15 mass parts or less, More preferably, it is 12 mass parts or less.

Here, when the usage amount (parts by mass) of the surface treating agent is “a” and the specific surface area (m ² / g) of the raw material silica particles is “b” with respect to 100 parts by mass of the raw material silica particles, (A / b) is preferably 0.1 or more and 0.6 or less. When it is within this range, the obtained silica particle dispersion is superior in long-term stability. More preferably, it is 0.12 or more, More preferably, it is 0.14 or more, More preferably, it is 0.3 or less, Especially preferably, it is 0.26 or less, More preferably, it is 0.25 or less, More preferably, it is 0.00. 23 or less, most preferably 0.21 or less.

The surface treatment agent is also preferably subjected to step (I) as a dispersion (or solution) containing a dispersion medium and the surface treatment agent. That is, it is preferable that the manufacturing method includes a step of preparing a dispersion (or solution) containing the surface treatment agent and the dispersion medium before the step (I). Thereby, mixing with silica particles becomes easier. It does not specifically limit as a dispersion medium used here, The thing similar to the dispersion medium preferably used by process (I) is mentioned. Among these, a mixed solvent of water-soluble alcohol and water is preferable.

Step (I) is preferably performed in the presence of a dispersion medium as described above. It does not specifically limit as a dispersion medium, For example, water, an organic solvent, or these mixed solvents etc. are mentioned.
Examples of the organic solvent include alcohol, acetone, dimethyl sulfoxide, dimethylformamide, tetrahydrofuran, dioxane and the like. Examples of the alcohol include monovalent water-soluble alcohols such as methanol, ethanol and propanol; bivalent or more such as ethylene glycol and glycerin. Of water-soluble alcohols. The dispersion medium is preferably water, and more preferably ion-exchanged water.

In the step (I), one or more other raw materials may be used in combination as necessary. Although it does not specifically limit as another raw material, For example, when other inorganic oxide particles other than a silica particle are used, the silicon-containing composite inorganic particle by which surface treatment was performed will be obtained by passing through process (II).
Although it does not specifically limit as another inorganic oxide particle, For example, what contains the element of element periodic table II-VI group is preferable, More preferably, the element of element periodic table III-IV is included. Among these, Al, Ti and / or Zr are preferable. The amount of other inorganic oxide particles used may be set as appropriate depending on the application and the like. For example, the total amount of raw material inorganic oxide particles (total amount of silica particles and other inorganic oxide particles) is 100% by mass. The content is preferably 50% by mass or less. More preferably, it is 30 mass% or less, More preferably, it is 10 mass% or less, Most preferably, it is 1 mass% or less (this is called "the form which uses only a silica particle substantially as raw material inorganic oxide particle").

The mixing means in the step (1) is not particularly limited, and examples thereof include stirring with a stirring blade, shaking stirring, stirring with a mixer, stirring with a stirrer, and the like. You may grind | pulverize by a bead mill, a ball mill, etc. as pre-processing of mixing.

The slurry obtained in step (I) preferably has a pH of 2-7. Thereby, the surface treatment of the silica particles in the step (II) is performed more efficiently. More preferably, it is 3 or more, More preferably, it is 3.5 or more, More preferably, it is 6 or less, More preferably, it is 5 or less.

In the slurry obtained in step (I), the concentration of the raw silica particles is preferably 5 to 50% by mass with respect to 100% by mass of the total amount of the slurry. By providing the slurry with the concentration of raw silica particles in this range to step (II), surface-coated silica particles with better compatibility with the solvent can be obtained, so the long-term stability when made into a dispersion is further improved To do. More preferably, it is 6 mass% or more, More preferably, it is 7 mass% or more, More preferably, it is 40 mass% or less, More preferably, it is 30 mass% or less.
In addition, it is also suitable to remove a dispersion medium after process (I) and before using for process (II). Thereby, surface treatment by process (II) is performed more efficiently. The method for removing the dispersion medium is not particularly limited, and examples thereof include filtration, stationary drying, spray drying, and vacuum drying.

-Step (II)-
Step (II) is a step of heating the mixture obtained in step (I) at 120 to 250 ° C. By heating at this temperature, that is, by heat-treating the mixture at this temperature, it is possible to obtain surface-treated silica particles having a strong bond between the surface treatment agent and the silica particles. When this is subjected to step (III), the surface treatment agent is sufficiently prevented from being released from the silica particles over time, and can maintain an appropriate hydrophobicity, and thus has a long-term stability. Is obtained.

The heating (heat treatment) temperature is preferably 125 ° C. or higher, more preferably 130 ° C. or higher, from the viewpoint of strengthening the bond between the surface treatment agent and the silica particles. Further, from the viewpoint of equipment, productivity, etc., it is preferably 230 ° C. or lower, more preferably 200 ° C. or lower, still more preferably 180 ° C. or lower, and particularly preferably 170 ° C. or lower.
In order to eliminate unevenness in heat treatment, it is preferable to perform the step (II) so as to obtain a uniform temperature distribution.

The heating (heat treatment) time is preferably 0.5 to 12 hours, for example. When it is 0.5 hour or longer, the bond between the surface treatment agent and the silica particles becomes stronger. Moreover, even if it exceeds 12 hours, the effect corresponding to it cannot fully be acquired, but productivity may not be improved more. More preferably, it is 0.5 to 6 hours.

In this specification, “heating temperature” means the maximum temperature during heating (heat treatment). “Heating time” means the holding time of the maximum temperature during heating, and does not include the temperature rising time until the maximum temperature is reached. The temperature raising time is not particularly limited, but is preferably as short as possible.

The heating method is not particularly limited, and may be, for example, a fluidized bed method or a fixed bed method. The atmosphere is not particularly limited, and the heat treatment may be performed in an inert gas atmosphere such as an air atmosphere, a nitrogen atmosphere, or an argon atmosphere.

Here, the step (II) may be a drying step as long as it is a step of heating at the above temperature. The drying method is not particularly limited, and examples thereof include stationary drying, spray drying, and vacuum drying. When spray drying is performed, it is preferable that the temperature in the collection hopper of the spray dryer is 120 to 250 ° C., and the heat treatment time is within the above range as the residence time in the collection hopper. However, from the viewpoint of strengthening the bond between the silica particle surface and the phenylalkoxysilane, the step (II) is preferably not a spray drying step.

In the manufacturing method, step (II) may be repeated a plurality of times as necessary. When the process is repeated a plurality of times, it is preferable that the total heating time is within the range of the preferable heating time described above.

-Step (III)-
Step (III) is a step of dispersing in a solvent. That is, the step is preferably a step of dispersing the surface-treated silica particles obtained in the step (II) in a solvent. The dispersion method is not particularly limited, and for example, a normal dispersion method such as a bead mill can be employed.

The solvent preferably has a relative dielectric constant of 5 to 30. Thereby, in addition to becoming a silica particle dispersion that is more useful for sealing material applications, the long-term stability of the dispersion is further improved. The solvent having such a relative dielectric constant is as described above.
In addition, although 1 type (s) or 2 or more types can be used for a solvent, when using 2 or more types, it is preferable that the relative dielectric constant as the whole mixed solvent exists in the said range.

The amount of the surface-treated silica particles used for dispersing in the solvent may be appropriately set depending on the use of the silica particle dispersion, etc., but is set so as to satisfy the concentration of the surface-treated silica particles in the silica particle dispersion described above. It is preferable to do.

2. Surface-treated silica particles Next, the surface-treated silica particles according to the second embodiment of the present invention will be described.
The surface-treated silica particles of the present invention are particles that are surface-treated with phenylalkoxysilane and have a degree of hydrophobicity of 15 to 35%. Thus, when at least a part of the hydroxyl groups on the surface of the silica particles are silica particles substituted with a group derived from phenylalkoxysilane, and the degree of hydrophobicity is in this range, the dispersion state can be stably maintained for a long time. A silica particle dispersion that can be maintained can be provided.
In addition, about the preferable form of a surface treatment silica particle, it is as having mentioned above in description of the silica particle dispersion which is a 1st aspect of this invention.

<Manufacturing method>
In order to obtain the surface-treated silica particles of the present invention, for example, the step (I) of mixing the silica particles and the surface treatment agent and the step of heating the mixture obtained in the step (I) to 120 to 250 ° C. (II It is preferable to employ a method for producing surface-treated silica particles, wherein the surface treatment agent contains phenylalkoxysilane. According to this production method, the surface-treated silica particles of the present invention can be obtained easily and simply. In this manufacturing method, one or more other steps may be included as necessary, and the other steps are not particularly limited.
Steps (I) and (II) are the same as steps (I) and (II) in the method for producing a silica particle dispersion described above, respectively.

3. Silica-containing resin composition Furthermore, the silica-containing resin composition which is the 3rd aspect of this invention is demonstrated.
The silica-containing resin composition of the present invention (also simply referred to as “resin composition”) includes the above-described silica particle dispersion of the present invention and a resin component. The resin composition may further contain other components as required, and each component can be used alone or in combination of two or more.

The resin component is not particularly limited as long as it is appropriately set depending on the application and the like. For example, when used for a sealing material, an epoxy resin is suitable.

In the above resin composition, the mass ratio of the silica particle dispersion to the resin component is not particularly limited as long as it is appropriately set depending on the application and the like. For example, the silica particle dispersion contains 100 parts by mass of the resin component. It is preferable to make the surface-treated silica particles to be 1 to 70 parts by mass. Thereby, the affinity between the surface-treated silica particles and the resin component is further increased. More preferably, it is 10 mass parts or more, More preferably, it is 60 mass parts or less.

-Application-
Since the silica-containing resin composition of the present invention is excellent in long-term stability, it is useful for various applications. Among them, it is particularly useful as a raw material for a film-like sealing material. That is, the silica-containing resin composition is particularly preferably a film-form sealing material resin composition. Although it does not specifically limit as a method of producing a film-form sealing material using this resin composition, For example, after coating a resin composition, it is preferable to volatilize a solvent and to make a film form. In addition, it can also be preferably used for various uses such as sealing materials of other shapes, film materials, toner materials, dental materials and the like. It is particularly suitable for use in semiconductors. Moreover, the sealing material containing the surface-treated silica particles of the present invention described above and a resin component is also included in the present invention. The sealing material is preferably in the form of a film.

In order to describe the present invention in detail, examples are given below, but the present invention is not limited to these examples. Various physical properties were evaluated as follows.

1. Particle properties (1) BET specific surface area (m ² / g)
The BET specific surface area was measured by a BET multipoint method using a GEMINI VII 2390 manufactured by Micromeritics, after heat-treating the sample at 200 ° C. for 40 minutes in a nitrogen atmosphere.

(2) Degree of hydrophobicity (%)
Add 50 mL of ion-exchanged water to a 200 mL beaker, then add 0.200 g of sample, add methanol with a burette while stirring with a stirrer, and add methanol until the sample floating on the liquid surface completely sinks And the degree of hydrophobicity was calculated from the following formula (1).
Hydrophobicity (%) = {Titration volume (mL) / [Titration volume (mL) +50 (mL)]} × 100 (1)

(3) Evaporated water content (ppm)
Using a water vaporizer EV-2000 manufactured by Hiranuma Sangyo Co., Ltd., after removing adsorbed water by heating at 150 ° C. for 30 minutes, the amount of water vaporized by heating at 210 ° C. for 20 minutes was measured. The water content was measured using AQV-2200 manufactured by Hiranuma Sangyo Co., Ltd., and HYDRANAL-Composite 5 manufactured by Fluka Co., Ltd. was used as the Karl Fischer reagent.

(4) Average SEM diameter Photographed with a scanning electron microscope JSM-840F manufactured by JEOL Ltd., and the captured SEM image file was read with image analysis software (A Image-kun (trademark)) manufactured by Asahi Kasei Engineering Co., Ltd. Using an application, the average SEM diameter of 50 or more silica particles was measured.

(5) CV value The CV value was calculated from the following mathematical formula (2).
CV value = SEM diameter standard deviation / average SEM diameter (2)
In the formula, the average SEM diameter means the average value of the SEM diameters of all particles measured for the SEM diameter.

2. Dispersion physical properties (1) Contact angle (°)
Each dispersion was dropped on a grind gauge (0-100 μm), coated uniformly using a scraper, and dried at room temperature for 90 minutes to prepare a coating film. Using a wettability evaluation apparatus LSE-B100 manufactured by Nick Corporation, 10 contact angles were measured with 5 μl of hanging drops on a coating film having a gauge scale of 20 to 60 μm, and the contact angle was calculated from the average value.

(2) Sedimentation rate (%)
50 g of each dispersion was weighed in a 140 ml mayonnaise bottle and allowed to stand at 24 to 26 ° C. for 1000 hours, and then the height (c) of the dispersion and the height (d) of the sediment were measured. The sedimentation rate was calculated from 3).
d / c × 100 (%) (3)

Preparation Example 1
After adding 2700 g of methanol to 6300 g of water, the temperature was raised to 50 ° C. 90 g of phenyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., Shin-Etsu Silicone KBM-103) was added to water and methanol solution maintained at 50 ° C., and stirred at 50 ° C. for 30 minutes to hydrolyze phenyltrimethoxysilane ( 1) was prepared.

Preparation Examples 2-7
Except having changed the raw material and its input amount as shown in Table 1, hydrolyzed liquids (2) to (7) of the surface treatment agent were prepared in the same manner as in Preparation Example 1. In Preparation Example 7, two types of surface treatment agents were used in combination. In Table 1, HMDS means hexamethyldisilazane.

Test example 1
Obtained in Preparation Example 1 with 3000 g of water and 1000 g of silica having a specific surface area of 47.0 m ² / g (manufactured by Sakai Chemical Industry, trade name “Sciqas 0.05 μm”, average SEM diameter: 0.07 to 0.08 μm) The entire amount of the hydrolyzed liquid (1) was added and stirred for 60 minutes using a stirring blade to prepare a silica slurry. The pH of the silica slurry was 3.99. The silica slurry was dried at a hot air inlet temperature of 300 ° C. and a hot air outlet temperature of 80 ° C. using a spray dryer (manufactured by Ashizawa Niro Atomizer, Mobile Miner type spray dryer), and then filled into a stainless steel vat, and 130 ° C. The surface-treated silica particles (1) were obtained by applying heat for 3 hours with a dryer set to 1.
The physical properties of the obtained surface-treated silica particles (1) were measured or evaluated by the method described above. The results are shown in Table 3.

Next, 42.0 g of surface-treated silica particles (1), 28.0 g of cyclohexanone, and 49.8 g of 0.7 mmΦ glass beads were weighed in a 140 ml mayonnaise bottle and dispersed for 40 minutes with a paint shaker manufactured by Red Devil. After the dispersion, the glass beads were separated with a nylon mesh (aperture 25 μm) to obtain a silica particle dispersion (1).
The physical properties of the obtained silica particle dispersion (1) were measured or evaluated by the method described above. The results are shown in Table 3.

Test Examples 2 to 15
Surface-treated silica particles (2) to (15) were obtained in the same manner as in Test Example 1 except that the temperature of the raw material and the dryer was changed as shown in Table 2. The physical properties of each surface-treated silica particle obtained were measured or evaluated by the method described above. The results are shown in Table 3.
Next, silica particle dispersions (2) to (15) were obtained in the same manner as in Test Example 1 except that the raw materials and the solvent were changed as shown in Table 2. The physical properties of each obtained silica particle dispersion were measured or evaluated by the method described above. The results are shown in Table 3.
The details of the raw silica particles used in Test Examples 7 and 15 are as follows.
Test Example 7: manufactured by Sakai Chemical Industry Co., Ltd., trade name “Sciqas 0.1 μm”, specific surface area: 21.2 m ² / g, average SEM diameter: 0.15 μm
Test Example 15: Sakai Chemical Industry Co., Ltd., trade name “Sciqas 0.25 μm”, specific surface area: 13.7 m ² / g, average SEM diameter: 0.24 μm

In Table 2, * 1 means a value (a / b) obtained by dividing the following a by b.
a: Use amount (parts by weight) of the surface treatment agent with respect to 100 parts by weight of the raw material silica particles.
b: Specific surface area of raw silica particles (m ² / g)

In Table 3, the following abbreviations mean the following compounds, respectively.
MEK: methyl ethyl ketone PGMEA: propylene glycol monomethyl ether acetate PGME: propylene glycol monomethyl ether

From the above example, the following was confirmed.
The silica particle dispersions obtained in Test Examples 1 to 11 are surface-treated with phenylalkoxysilane and include surface-treated silica particles having a hydrophobization degree of 15 to 35% and a solvent. In the silica particle dispersions obtained in 12 to 15, the degree of hydrophobicity of the surface-treated silica particles is less than 15% or more than 35%, and Test Examples 13 and 14 show that phenylalkoxy is obtained when the surface-treated silica particles are obtained. This is an example using a surface treating agent other than silane. Under such a difference, when the sedimentation degree of the silica particle dispersion after standing for 1000 hours was compared, the dispersions obtained in Test Examples 1 to 11 were settled against the dispersions obtained in Test Examples 12 to 15. The degree is remarkably low. Therefore, when the dispersion is composed of a surface-treated silica particle having a surface treatment with phenylalkoxysilane and having a hydrophobicity of 15 to 35% and a solvent, sedimentation of the silica particles is sufficiently suppressed, It was found that it was easy to store and transport and could maintain a dispersed state stably for a long time.

Although not described in the table, the temperature of the dryer when obtaining the surface-treated silica particles in Test Example 2 was changed, and the influence of the difference in temperature on the sedimentation rate of the silica particle dispersion was examined. It was found that when the temperature of the dryer was 120 ° C. or higher (in particular, 130 ° C. or higher as in Test Example 2), the sedimentation rate was significantly reduced. When the dryer temperature was less than 120 ° C., the vaporized water content of the surface-treated silica particles after drying exceeded 600 ppm.
Further, in Test Example 1, the solvent used for preparing the silica particle dispersion was changed, and the influence of the difference in the solvent on the sedimentation rate of the silica particle dispersion was examined. Test Examples 1, 8 to 10 (solvent : Cyclohexanone, MEK, PGMEA or PGME), the sedimentation rate is much higher than when cyclohexane, methanol or water is used as the solvent (that is, when a solvent having a relative dielectric constant outside the range of 5 to 30 is used). It was found that the dispersion state was maintained more stably.

Claims (12)

A silica particle dispersion comprising surface-treated silica particles and a solvent,
The surface-treated silica particles are surface-treated with phenylalkoxysilane and have a degree of hydrophobicity of 15 to 35%. 2. The silica particle dispersion according to claim 1, wherein the surface-treated silica particles have a vaporized water content at 150 to 210 ° C. of 600 ppm or less. The silica particle dispersion according to claim 1 or 2, wherein the solvent has a relative dielectric constant of 5 to 30. The silica particle dispersion according to claim 1, wherein the surface-treated silica particles have an average SEM diameter of 0.05 to 0.20 μm. 5. The silica particle dispersion according to claim 1, wherein the concentration of the surface-treated silica particles in the dispersion is 30 to 70% by mass. The silica particle dispersion according to any one of claims 1 to 5, wherein a sedimentation rate after standing for 1000 hours is 10% or less. A method for producing the silica particle dispersion according to any one of claims 1 to 6,
The manufacturing method is as follows:
Mixing the silica particles and the surface treatment agent (I);
A step (II) of heating the mixture obtained in the step (I) to 120 to 250 ° C .;
Including dispersing in a solvent (III),
The method for producing a silica particle dispersion, wherein the surface treatment agent comprises phenylalkoxysilane. Surface-treated silica particles characterized by being surface-treated with phenylalkoxysilane and having a hydrophobicity of 15 to 35%. A method for producing the surface-treated silica particles according to claim 8,
The manufacturing method is as follows:
Mixing the silica particles and the surface treatment agent (I);
Heating the mixture obtained in step (I) to 120-250 ° C., and
The method for producing surface-treated silica particles, wherein the surface treatment agent comprises phenylalkoxysilane. A silica-containing resin composition comprising the silica particle dispersion according to any one of claims 1 to 6 and a resin component. It is a resin composition for film-form sealing materials, The silica containing resin composition of Claim 10 characterized by the above-mentioned. A sealing material comprising the surface-treated silica particles according to claim 8 and a resin component.