JP2009013033A - Method for producing surface-coated silica organosol and method for producing surface-coated silica particle-containing epoxy resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily producing a surface-coated silica organosol which has excellent dispersibility when mixing an epoxy compound, has hardly any increase of the viscosity or hardening with the passage of time in the obtained epoxy resin composition and impart good storage stability, and to provide an epoxy resin composition excellent in storage stability and dispersion stability obtained by mixing the surface-coated silica organosol and the epoxy compound. <P>SOLUTION: The method for producing the surface-coated silica organosol comprises the following 1 and 2. 1. The method for producing the surface-coated silica organosol is characterized by carrying out the following steps (A) and (B) in this order, in which the method comprises the step of (A) carrying out hydrolysis condensation reaction by adding a silane coupling agent to the silica organosol and the step of (B) controlling the pH of the resultant product to neutral by removing an acidic catalyst from the resultant product of (A). 2. The method for producing a surface-coated silica particle-containing epoxy resin composition is characterized by carrying out the following steps (C) and (D) in this order using the surface-coated silica organosol obtained by the production method 1, in which the method comprises the step of (C) mixing the epoxy compound with the surface-coated silica organosol and the step of (D) removing the organic solvent from the resultant product of (C). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a surface-coated silica organosol and a method for producing a surface-coated silica particle-containing epoxy resin composition. In detail, it is related with the manufacturing method of the organosol containing the silica particle surface-coated by the silane coupling agent, and the manufacturing method of the epoxy resin composition using the said solution and an epoxy compound.

Epoxy resin compositions in which silica particles are dispersed as a filler in an epoxy compound are generally excellent in mechanical characteristics, thermal characteristics, optical characteristics, etc., and as various molding materials, particularly light emitting diodes (LEDs). It is used as a sealing material for semiconductor elements such as the above.

By the way, when silica particles are used as a solid (powder), it is generally difficult to finely disperse them in the epoxy compound. For example, the epoxy resin composition becomes cloudy or the silica particles are precipitated by secondary aggregation. Further, when silica particles are used as a hydrosol, it is difficult to uniformly mix with an organic epoxy compound. Therefore, generally in the industry, silica particles are often dispersed in an organic solvent and used as a silica organosol.

  However, when a silica organosol and an epoxy compound are mixed, the resulting epoxy resin composition may thicken or harden over time. This is considered because the silanol group which exists in the silica particle surface in a silica organosol reacts with the epoxy group of an epoxy compound also at normal temperature. When the storage stability is inferior as described above, for example, when the obtained epoxy resin composition is sealed in a mold, it is difficult to spread the details, and there is a concern that voids, cracks, and the like may occur in the obtained molded product. There is.

Therefore, it is considered useful to surface-treat the silica particles in the silica organosol by some means and control the amount of silanol groups. For example, Patent Document 1 discloses a technique for controlling the amount of silanol groups by surface-treating silica particles with a silane coupling agent, and it is conceivable to use the treated silica particles as a silica organosol.

An organosol containing such surface-coated silica particles (hereinafter referred to as surface-coated silica organosol) is generally produced by adding a silane coupling agent to a silica organosol containing silica particles and subjecting it to a hydrolytic condensation reaction. .

However, after completion of the reaction, a part of the silane coupling agent component remaining without reacting with the silica particles may undergo self-condensation over time to form a network structure (gel). In this case, the epoxy resin composition using the obtained surface-coated silica organosol may increase in viscosity over time, causing problems in quality control, as well as mechanical and optical properties of the molded product. There is a concern that the thermal characteristics and the like deteriorate.

  Therefore, it is necessary to use an acidic catalyst for the purpose of increasing the reaction efficiency between the silica particles and the silane coupling agent. However, when the surface-coated silica organosol obtained using an acidic catalyst is mixed with an epoxy compound, the resulting epoxy resin composition rapidly thickens or hardens. This is considered to be because the ring-opening reaction of the epoxy compound is promoted because the surface-coated silica organosol contains a large amount of acid.

  Therefore, it is conceivable to neutralize the acidic catalyst in the surface-coated silica organosol with a neutralizing agent such as ammonia. However, it is considered that the neutralized salt becomes an impurity and adversely affects the physical properties of the final epoxy resin composition and molded products using the same. Moreover, since the impurities are naturally mixed in the epoxy resin composition, it is generally difficult to remove them, which makes the process complicated and increases the cost of the final product (molded product). Invite.

JP 2001-31843 A

The present invention is a surface-coated silica organosiloxane that has excellent storage stability, such as excellent dispersibility when mixed with an epoxy compound, and the resulting epoxy resin composition hardly thickens or hardens over time. The main object is to provide a method for easily producing a sol. Another object is to provide an epoxy resin composition excellent in storage stability and dispersion stability obtained by mixing the surface-coated silica organosol and an epoxy compound.

  The present inventor has found that the surface-coated silica organosol and the epoxy resin composition can be produced by a specific process. That is, this invention relates to the following manufacturing method.

1. The manufacturing method of the surface coating | coated silica organosol characterized by implementing the process of following (A)-(B) in this order.
(A) A step of adding a silane coupling agent to the silica organosol and performing a hydrolysis-condensation reaction in the presence of an acidic catalyst (B) removing the acidic catalyst from the resultant product of (A), Step of adjusting pH to neutral

2. In the step (B), the method for removing an acidic catalyst is based on an anion exchange resin, and the pH is 6 to 8.

3. In the step (A), the hydrolytic condensation reaction is carried out at 50 to 90 ° C. in the presence of sulfuric acid.

4). In the step (A), 0.2 to 20 mmol of a silane coupling agent is added to 1 g of silica particles in the silica organosol.

5). (B) The manufacturing method in any one of said 1-4 whose surface coating amount of a silica particle in the surface coating silica organosol obtained after a process is 0.2-3 mmol / g.

6). The surface-coated silica obtained by performing the following steps (C) to (D) in this order using the surface-coated silica organosol obtained by any one of the production methods 1 to 5 above: A method for producing a particle-containing epoxy resin composition.
(C) Step of mixing an epoxy compound with the surface-coated silica organosol (D) Step of removing an organic solvent from the resultant product of (C)

The surface-coated silica organosol obtained by the production method of the present invention is excellent in storage stability such that it itself hardly thickens or hardens over time. Moreover, since the said surface coating silica organosol is excellent in the dispersibility in an epoxy compound, according to this, the epoxy resin composition excellent in storage stability can be provided.

Moreover, the epoxy resin composition obtained by the production method of the present invention is excellent in storage stability and dispersion stability. The epoxy resin composition is particularly useful as a sealing material for an optical semiconductor element such as a light emitting diode (LED) because it has excellent mechanical characteristics, thermal characteristics, optical characteristics and the like when formed into a molded product.

  The surface-coated silica organosol according to the present invention can be produced by the following steps.

(A) A step of adding a silane coupling agent to the silica organosol and performing a hydrolysis-condensation reaction in the presence of an acidic catalyst (B) removing the acidic catalyst from the resultant product of (A), Step of adjusting pH to neutral

[About (A) process]
In step (A), the surface of the silica particles is subjected to a hydrolytic condensation reaction (coupling reaction) between the silanol groups on the surface of the silica particles in the silica organosol and the organic groups of the silane coupling agent. This is a step of surface coating treatment with a coupling agent. Here, “silica organosol” refers to an organosol (colloidal solution) in which silica (silicon dioxide) particles are dispersed particles and an organic solvent is a dispersion medium, and usually has a transparent or milky white appearance.

The silica organosol is not particularly limited, and those produced by various known methods can be used. For example, a method of polycondensing sodium silicate, a method of hydrolyzing alkoxysilanes in an aqueous alcohol solution (sol-gel method), or a colloidal solution in which commercially available silica particles are dispersed in an organic solvent by a known method Can do. The solid content concentration of the silica organosol is usually about 1 to 60% by weight, preferably 5 to 50% by weight.

  The shape of the silica particles is not particularly limited, and may be spherical or flat, and may be primary particles or a secondary or higher aggregation state. The primary average particle size (meaning the average particle size of primary particles by dynamic light scattering method; hereinafter the same) is not particularly limited and can be appropriately selected depending on the application. For example, when used as an optical semiconductor sealing material, the primary average particle diameter is usually 500 nm or less, preferably about 10 to 450 nm.

  The organic solvent is not particularly limited, and various known solvents can be used. Specifically, for example, methanol, ethanol, isopropyl alcohol, n-butanol, n-octanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, propyl glycol monomethyl ether, propyl glycol monoethyl ether Alcohols such as ethyl acetate, n-butyl acetate, ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and γ-butyrolactone; lactones; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. Ketones; amides such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc. Lactams; benzene, toluene, aromatic hydrocarbons xylene and the like; and the like, which may be used alone or in combination of two or more, of them. In consideration of the influence on the anion exchange resin described later, the organic solvent is preferably a hydrophilic organic solvent, specifically the alcohols, esters or lactones.

  The silica organosol may be a commercially available product. Specifically, for example, methanol silica sol, IPA-ST, MEK-ST, MIBK-ST, XBA-ST, DMAC-ST, ST-20, ST-40, ST-C, ST-N, ST-O, ST-50, ST-OL (manufactured by Nissan Chemical Industries, Ltd.), organosol PL-2PGME (propylene glycol monomethyl ether dispersion, manufactured by Fuso Chemical Industries, Ltd.), and the like.

  Specific examples of commercially available silica particles include Aerosil 130, Aerosil 300, Aerosil 380, Aerosil TT600, Aerosil OX50 (above, Nippon Aerosil Co., Ltd.), Sildex H31, Sildex H32, Silsil Dex H51, Sildex H52, Sildex H121, Sildex H122 (above, Asahi Glass Co., Ltd.), E220A, E220 (above, Nihon Silica Industry Co., Ltd.), SYLYSIA470 (Fuji Silysia Ltd.), SG And flakes (manufactured by Nippon Sheet Glass Co., Ltd.).

The silane coupling agent is not particularly limited as long as it has an organic functional group and a hydrolyzable group in one molecule, and various known ones can be used. The silane coupling agent is specifically represented by the general formula (1): YRSiX ₃ (wherein Y is a vinyl group, amino group, thiol group or halogen group, R is a hydrocarbon group, and X is an alkoxy group. Represents a halogen group or an amino group.

  Specific examples of the silane coupling agent include, for example, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane. Alkoxysilanes such as isobutyltrimethoxysilane; 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycid Xylpropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryl Epoxy group-containing alkoxysilanes such as acryloxypropyltriethoxysilane; N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (amino Ethyl) 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, amino group-containing alkoxysilanes such as N-phenyl-3-aminopropyltrimethoxysilane; methyltrichlorosilane, Methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, vinyltrichlorosilane, trimethylbromosilane, 3,3,3-trifluoropropyltrimethoxysilane Halogen group-containing alkoxysilanes such as methyl-3,3,3-trifluoropropyldimethoxysilane; vinyl group-containing alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris (β-methoxyethoxy) silane; Mercaptopropyltrimethoxysilane, trimethylsilanol, diethylsilane, and the like. These may be used alone or in combinations of two or more. In the present invention, since the surface-coated silica organosol can be favorably dispersed in an epoxy compound described later, the epoxy group-containing alkoxysilanes, particularly 3-glycidoxypropyltrimethoxysilane, are preferred.

The hydrolysis condensation reaction is performed in the presence of an acidic catalyst, water, and, if necessary, the organic solvent. The conditions for the hydrolytic condensation reaction are not particularly limited and depend on various known examples. For example, the reaction temperature is about 50 to 90 ° C., and the reaction time is about 1 to 20 hours. Further, it is desirable that substances (water, methanol, etc.) generated by the hydrolysis condensation reaction are successively distilled off from the reaction system. Moreover, the solid content concentration of the reaction system during the hydrolysis-condensation reaction is usually about 5 to 60% by weight.

  Various known catalysts can be used as the acidic catalyst. Specific examples include inorganic acidic catalysts such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acidic catalysts such as formic acid and acetic acid, and an inorganic acidic catalyst, particularly sulfuric acid is preferable because the hydrolysis condensation reaction rate is easily improved. Moreover, although the usage-amount of an acidic catalyst is not specifically limited, Usually, it is about 0.1 to 5 weight% with respect to a silane coupling agent.

The amount of the silane coupling agent added to the silica organosol is not particularly limited. However, in consideration of the degree of coating of the surface-coated silica organosol to be obtained, normally, with respect to 1 g of silica particles in the silica organosol, The silane coupling agent is usually about 0.2 to 20 mmol, preferably 0.4 to 15 mmol.

[About (B) process]
The step (B) is a step of adjusting the pH of the resultant product to neutral by removing the acidic catalyst from the resultant product of the step (A). By setting the pH in the neutral range, the storage stability of the resulting surface-coated silica organosol is improved, and the storage stability of an epoxy resin composition using the surface-coated silica organosol is also preferable. In addition, that pH is neutral means specifically that pH is about 6-8.

  The method for removing the acidic catalyst is not particularly limited, but it is preferable to use an anion exchange resin in consideration of storage stability and transparency of the epoxy resin composition described later. In addition, when various neutralizing agents (ammonia, organic amines, metal hydroxides, etc.) are added to the resultant product of step (A) to neutralize the pH, it can be obtained due to the effects of neutralizing salts, etc. The resulting epoxy resin composition may become turbid or the surface-coated silica organosol may aggregate.

  As the anion exchange resin, various known ones (strong basicity (type I, type II), weak basicity) can be used without particular limitation, and the structure thereof may be gel or macroporous. Specifically, for example, styrene-divinylbenzene-based crosslinked polystyrene, acrylic acid-based polyacrylate, a heat-resistant aromatic polymer into which an ether group or a carbonyl group is introduced, and the like, and an amino group or a substituted amino group as an anion exchange group are used. A group into which a group, a quaternary ammonium group, a carboxyl group or the like is introduced is used.

  In the present invention, strongly basic anion exchange resins are preferred, and in particular, those in which the ion exchange group is a quaternary ammonium group having a trialkyl-substituted nitrogen atom or a quaternary ammonium group having a dialkylethanolamine cation. Is preferred. When a Cl-type anion exchange resin is used, Cl ions are contained in the epoxy resin composition, which may cause corrosion of various electronic materials. Therefore, in the present invention, particularly, an OH-type anion is used. Exchange resins are preferred.

  Examples of commercial products of the anion exchange resin include Amberlite IRA402BL OH type (manufactured by Organo), SBR-PC OH type (manufactured by Muromachi Chemical), Dowex Monosphere 550A, Marathon MSA (manufactured by Dow Chemical), Lebatit series. (Manufactured by Bayer), Diaion SA series, PA series (manufactured by Mitsubishi Chemical Corporation) and the like.

  (A) Although the time which processes the result of a process with an anion exchange resin is not specifically limited, Usually, it is 10-80 degreeC and it is about SV (Space Velocity) = 1-15 quantity. Further, the concentration of the resultant product is not particularly limited, but is usually about 5 to 60% by weight. Further, the number of treatments is not particularly limited, and the treatment can be repeated until the pH reaches about 6 to 8.

  The surface-coated silica organosol thus obtained usually has a primary average particle diameter (by dynamic light scattering method) of silica particles immediately after production of 500 nm or less, specifically about 5 to 450 nm, and a pH of 6 to 6. It is about 8, and the water content is about 0.1 to 10% by weight.

The silica particles in the surface-coated silica organosol have a certain surface coating amount due to the silane coupling agent. Here, the “surface coating amount” is an index representing the degree of coating of silica particles in the surface-coated silica organosol with a silane coupling agent, and the surface of 1 g of silica particles in the surface-coated silica organosol is actually used. It is a value expressed in moles (mmol / g) of the silane coupling agent coated on the surface. In the present invention, considering the storage stability of the epoxy resin composition, the surface coating amount is about 0.2 to 3 mmol / g, preferably 0.4 to 2.5 mmol / g. By setting it to 0.2 mmol / g or more, the viscosity of the resulting epoxy composition can be reduced after the step of removing the organic solvent (D) described later, or the storage stability (viscosity stability) of the epoxy composition. Can be improved. On the other hand, by setting it as 3 mmol / g or less, excessive aggregation of silica particles in the surface-coated silica organosol is suppressed, and a predetermined fluidity can be imparted to the epoxy resin composition.

  By using the surface-coated silica organosol thus obtained, the following steps (C) to (D) are carried out in this order, whereby a surface-coated silica particle-containing epoxy resin composition can be produced.

(C) Step of mixing an epoxy compound with the surface-coated silica organosol (D) Step of removing an organic solvent from the resultant product of (C)

[About step (C)]
As the epoxy compound used in the step (C), various known compounds can be used without particular limitation. Specifically, for example, aromatic epoxy compounds such as bisphenol A type epoxy compounds, bisphenol S type epoxy resins, bisphenol F type epoxy compounds, phenol novolac type epoxy compounds, cresol novolac type epoxy compounds; Hydrogenated epoxy compounds having an alicyclic structure formed by hydrogenating aromatic rings, vinylcyclohexene dioxide, dicyclopentadiene oxide, 3,4-epoxy-1- [8,9-epoxy-2,4-dioxaspiro [5 .5] Epoxy- [epoxy-oxaspiro C8-15 alkyl] -cycloC5-12 alkane, 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate such as undecan-3-yl] -cyclohexane 4,5-epoch Epoxy C5-12 cycloalkyl C1-3 alkyl-epoxy C5-12 cycloalkanecarboxylate, such as cycyclooctylmethyl-4 ', 5'-epoxycyclooctanecarboxylate, bis (2-methyl-3,4-epoxycyclohexyl) Alicyclic epoxy compounds such as bis (C1-3 alkyl epoxy C5-12 cycloalkyl C1-3 alkyl) dicarboxylate such as methyl) adipate; nitrogen-containing ring epoxy resins such as hydantoin epoxy resins; aliphatic epoxy resins; Examples thereof include glycidyl ether type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, and the like, and these can be used alone or in combination of two or more. Among these, considering the thermal characteristics (particularly discoloration resistance) and optical characteristics (particularly transparency) of the resulting epoxy resin composition, the liquid appearance is transparent, and the powdery form If it is a thing, the thing whose appearance is transparent when it is set as the solution of an organic solvent is preferable, and such an alicyclic epoxy compound is especially preferable.

The amount of the surface-coated silica organosol mixed with the epoxy compound is not particularly limited, and can be appropriately adjusted depending on the use of the resulting epoxy resin composition. Specifically, for example, with respect to 100 parts by weight of the epoxy compound (solid content), the surface-coated silica organosol is usually about 3 to 70% by weight, preferably about 5 to 60 parts by weight in terms of the weight of the silica particles. This is the range.

  In addition, in the case of the said mixing, the said organic solvent and various surfactant can also be used as needed.

  The mixing means is not particularly limited, and various known means that can disperse the surface-coated silica organosol in an epoxy compound can be used. The mixing temperature is usually room temperature, and the mixing time is usually about 10 minutes to 5 hours.

[About (D) process]
Step (D) is a step of removing the organic solvent from the resultant product of step (C) using various known means. Usually, it is preferably carried out by distillation under reduced pressure, the temperature is usually about 30 to 100 ° C., the pressure is about 1 to 150 hPa, and the time is about 15 minutes to 5 hours.

  Thus, a solution-like epoxy resin composition is obtained. The composition is a composition in which the surface-coated silica organosol and an epoxy compound are combined, and silica particles are finely dispersed in an epoxy resin as a matrix component.

Further, the physical properties such as pH, viscosity, epoxy equivalent (JISK7236) of the epoxy resin composition are not particularly limited, and can be appropriately determined according to the application. Moreover, the solid content is about 80-100 weight part.

Moreover, various additives can be used for this epoxy resin composition in the range which does not impair the effect of this invention as needed according to a use. Specifically, for example, aliphatic polyols (ethylene glycol, propylene glycol, etc.), carbon dioxide generation inhibitors such as phenolic compounds; flexibility imparting agents such as polyalkylene glycols, polydimethylsiloxane derivatives; various rubbers Impact resistance improvers such as and organic polymer beads; antioxidants, plasticizers, lubricants, silane coupling agents, flame retardants, antistatic agents, leveling agents, ion trapping agents, slidability improving agents, far-modifying agents , Surface tension reducing agents, antifoaming agents, anti-settling agents, ultraviolet absorbers, antioxidants, mold release agents, fluorescent agents, colorants, conductive fillers, and the like. Alternatively, two or more kinds can be used in combination. Moreover, when making this epoxy resin composition into a molded article, various hardening | curing agents and hardening accelerators can be used.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to this Example at all.

Example 1-1 (Production of surface-coated silica organosol)
[(A) Process]
In a four-necked round bottom flask equipped with a stirrer, stirring blade, condenser, dropping funnel, thermometer and nitrogen line, silica organosol solution (trade name “IPA-ST”, manufactured by Nissan Chemical Industries, Ltd., dispersion medium is Isopropyl alcohol), silica particles have a primary average particle diameter of about 400 nm, 300 g (solid content weight 90 g), concentrated sulfuric acid 0.5 g, deionized water 11 g, and isopropyl alcohol 331.7 g, while stirring under a nitrogen stream. The temperature was raised to 80 ° C. Next, a solution obtained by dissolving 24 g of silane coupling agent (trade name “KBM-403”, manufactured by Shin-Etsu Chemical Co., Ltd., 3-glycidoxypropyltrimethoxysilane) with 272 g of isopropyl alcohol was added to the reaction system over 1 hour. After completion of the dropwise addition, the hydrolysis condensation reaction was carried out by maintaining the temperature under reflux for 6 hours.

[(B) Process]
Next, the reaction system was cooled to 25 ° C., and 820 g of the solution obtained in the step (A) was packed with 400 mL of OH type anion exchange resin (trade name “Amberlite 402J OH”, manufactured by Organo Corporation). The sulfuric acid was removed by passing the solution at a rate of 5 mL / min. Thus, a surface-coated silica organosol having a primary average particle size of about 20 nm and a pH of 7.5 (dispersion medium is isopropyl alcohol) was obtained.

  The primary average particle diameter is a value measured using a commercially available dynamic light scattering apparatus (product name “FPAR-3” using a concentrated probe, average particle diameter by cumulant analysis, manufactured by Otsuka Electronics Co., Ltd.). It is.

  The pH is a value measured using a commercially available pH meter (D-52, manufactured by Horiba, Ltd.). The measurement was performed in a state where the obtained surface-coated silica organosol was diluted with water so that the solution concentration was 1%.

  Further, for the surface-coated silica organosol, the following operations and calculations were performed in order to determine the surface coverage of the surface-coated silica particles.

An operation for removing the unreacted silane coupling agent component from the surface-coated silica organosol was performed. Specifically, first, the surface-coated silica organosol was mixed with hexane. At this time, the mixed solution became cloudy and the silica particles in the sol agglomerated. Next, the obtained mixed liquid was subjected to a centrifugal separator (3000 rpm, 30 minutes), and the silica particles were settled to separate the dispersion medium (isopropyl alcohol) and the silica particles. Next, the dispersion medium was removed, and instead, tetrahydrofuran was added to disperse the silica particles, and hexane was further added to aggregate the silica particles. Thereafter, this operation was repeated 5 times. Thereafter, the silica sol as a residue was dried with a dryer at 105 ° C. for 3 hours. The obtained dried product is hereinafter referred to as “residue”.

Next, differential thermothermogravimetric simultaneous measurement (TG-DTA) is performed on the residue, and the obtained weight loss is desorbed from the organic component portion of the silane coupling agent bonded to the silanol group in the surface-coated silica particles. The surface coating amount was calculated according to the following general formula (2).

The TG-DTA measurement (hereinafter simply referred to as measurement) was performed up to 800 ° C. at 10 ° C./min. In addition, “TG-DTA 2000S” manufactured by Bruker Axs Co., Ltd. was used as a measuring device.

The “organic component portion” corresponds to the “YR” portion in the general formula (1). In the case of Example 1-1, 3-glycidoxypropyltrimethoxysilane (molecular weight≈ 236) corresponds to a 3-glycidoxypropyl group (molecular weight≈115).

General formula (2): Surface coverage _{(mmol / g)} = A _(mol) / C _(g) × 1000

A: Mol of organic component part of silane coupling agent covering surface-coated silica particles = [(residual weight before measurement) − (residual weight after measurement)] / (molecular weight of organic component part) ] = (1.01 × 10 ⁻² −9.3 × 10 ⁻³ ) /115=6.96×10 ⁻⁶

B: Weight of silane coupling agent covering surface-coated silica particles _(g) = A × (molecular weight of silane coupling agent) = 6.96 × 10 ⁻⁶ × 236 = 1.64 × 10 ⁻³

C: Weight of the silica particles themselves of the surface-coated silica particles _(g) = (residual weight before measurement) −B = 1.01 × 10 ⁻² −1.64 × 10 ⁻³ = 8.46 × 10 ⁻³

From the above, the surface coating amount _{(mmol / g)} of the surface-coated silica particles in the surface-coated silica organosol of Example 1-1 was;

A _(mol) / C _(g) × 1000 = 6.96 × 10 ⁻⁶ _(mol) /8.46×10 ⁻³ _(g) × 1000≈0.8.

Examples 1-2 to 1-5
Each surface-coated silica organosol was obtained in the same manner except that the amount of the silane coupling agent used in Example 1-1 was changed to the amount shown in Table 1. In addition, Table 1 shows the primary average particle diameter, surface coating amount, and pH.

(Evaluation of storage stability (viscosity stability) of surface-coated silica organosol)
Each surface-coated silica organosol of Examples 1-1 to 1-5 was left in a thermostatic chamber at 40 ° C. for 10 days. The range of change in viscosity before and after standing was evaluated according to the following criteria. The results are shown in Table 1.
○: Viscosity change rate is less than 20% Δ: Viscosity change rate is 20-30%

Example 2-1 (Production of epoxy resin composition)
[(C) Process]
In a round bottom flask equipped with a magnetic stirrer, a condenser, and a thermometer, 330 g of the above surface-coated silica organosol, 100 g of an alicyclic epoxy compound (trade name “Celoxide 2021”, manufactured by Daicel Chemical Industries, Ltd.), and 32.9 g of isopropyl alcohol was charged and stirred at room temperature for 1 hour.

[(D) Process]
Subsequently, isopropyl alcohol was distilled off from the mixed solution obtained in the step (C) under the conditions of 40 ° C. and 50 hPa to obtain 332.8 g of an epoxy resin composition having a solid content of about 97% by weight.

Examples 2-2 to 2-5
Using each surface-coated silica organosol of Examples 1-1 to 1-5, each epoxy resin composition having a solid content of about 97% by weight was obtained in the same manner as in Example 2-1.

(Evaluation of storage stability (viscosity stability) of epoxy resin composition)
Each epoxy resin composition of Examples 2-1 to 2-5 was allowed to stand in a temperature-controlled room at 40 ° C. for 10 days. The range of change in viscosity before and after standing was evaluated according to the following criteria. The results are shown in Table 2.
○: Viscosity change rate is less than 20% Δ: Viscosity change rate is 20-30%

(Evaluation of transparency of epoxy resin composition)
The epoxy resin composition of Example 2-1, methylhexahydrophthalic anhydride (trade name “HN-5500E”, manufactured by Hitachi Chemical Co., Ltd.) as a curing agent, and tetra n-butylphosphonium o as a curing accelerator , O-diethyl phosphorodithioate (trade name “PX-4ET”, manufactured by Nippon Chemical Industry Co., Ltd.) was mixed at a weight ratio (in terms of solid content) of 100: 100: 1. Next, the obtained mixture was poured into an aluminum cup, preheated at 110 ° C. for 3 hours, and then heated at 130 ° C. for 3 hours to prepare a plate-like cured product having a thickness of 2 mm. Each plate-shaped cured material was similarly produced about each epoxy resin composition of Examples 2-2 to 2-5.

About each plate-shaped hardened | cured material, the light transmittance (%) in wavelength 470nm was measured using the commercially available ultraviolet visible spectrophotometer (Product name "U-3300", Hitachi Ltd. make). The results are shown in Table 2. Such transparency evaluation serves as an index for evaluating the dispersibility of the surface-coated silica particles in each epoxy resin composition.

Claims (6)

The manufacturing method of the surface coating | coated silica organosol characterized by implementing the process of following (A)-(B) in this order.
(A) A step of adding a silane coupling agent to the silica organosol and performing a hydrolysis-condensation reaction in the presence of an acidic catalyst (B) removing the acidic catalyst from the resultant product of (A), Step of adjusting pH to neutral The method according to claim 1, wherein in the step (B), the method for removing the acidic catalyst is based on an anion exchange resin, and the pH is 6-8. The process according to claim 1 or 2, wherein the hydrolysis condensation reaction is performed at 50 to 90 ° C in the presence of sulfuric acid in the step (A). In the step (A), 0.2 to 20 mmol of a silane coupling agent is added to 1 g of silica particles in the silica organosol. (B) The manufacturing method in any one of Claims 1-4 whose surface coating amount of a silica particle is 0.2-3 mmol / g in the surface coating silica organosol obtained after a process. A surface coating characterized by using the surface-coated silica organosol obtained by the production method according to any one of claims 1 to 5 and performing the following steps (C) to (D) in this order: A method for producing a silica particle-containing epoxy resin composition.
(C) Step of mixing an epoxy compound with the surface-coated silica organosol (D) Step of removing an organic solvent from the resultant product of (C)