JP2022146989A - silica-titania composite oxide - Google Patents

Abstract

To provide an inorganic powder that can be used as a curing agent for curing an epoxy resin, and can also be used as a filler which can reduce a coefficient of linear expansion of a cured product of the epoxy resin and thereby increase the reliability of the cured product.SOLUTION: A silica-titania composite oxide has a BET specific surface area of 25 to 60 m2/g and preferably 25 to 40 m2/g; and an acid amount at pKa of 4.1 or smaller, which can be detected by an amine titration method using bromophenol blue as an indicator, of 0.1 μmol/m2 or more and preferably 0.15 μmol/m2 or more. An acid site at pKa of 4.1 or smaller promotes curing of the epoxy resin, but if the specific surface area is too small, the absolute amount of acid sites also decreases, and the composite oxide resists showing the effect as a curing agent, and if the specific surface area is too large, the composite oxide resists being poured in the epoxy resin. Such a silica-titania composite oxide can be produced by a method of vaporizing a siloxane compound and a titanium alkoxide, and utilizing a combustion reaction of the mixture.SELECTED DRAWING: None

Description

The present invention relates to novel silica-titania composite oxides. Specifically, a silica-titania composite oxide that can be used as a curing agent for curing epoxy resins and as a filler capable of reducing the coefficient of linear expansion of the cured epoxy resin and increasing the reliability of the cured product. Regarding.

Epoxy resins are used in various applications such as adhesives, sealants, and coating agents.

In general, epoxy resins are added with curing agents and curing accelerators as components for promoting the curing reaction.

Epoxy resin is also used as a sealing material for semiconductors. For example, in a flip chip package, it is used as an underfill agent for protecting the connected semiconductor chip, wiring board, and bumps. Since the epoxy resin, the semiconductor chip, and the wiring board each have different coefficients of linear expansion, cracks may occur in the connecting portion if the connecting portion cannot absorb the stress. In order to suppress the occurrence of cracks, the underfill agent is mixed with a filler having a relatively small coefficient of linear expansion, such as silica.

In recent years, various additives have been added to underfill agents in addition to epoxy resins, curing agents, and fillers in order to improve the performance of cured products (for example, Patent Documents 1 and 2). To simplify the manufacturing process, materials with multiple properties such as fillers that can be used as curing agents are desired.

JP 2018-135429 A JP 2020-186397 A

An object of the present invention is to provide a silica-titania composite oxide that can be used as a curing agent for curing epoxy resins and that can reduce the coefficient of linear expansion of cured epoxy resins and improve the reliability of the cured products. to do.

The inventors of the present invention have made intensive studies to solve the above object. As a result, the inventors have found that a silica-titania composite oxide having a strong solid acid can be used as a filler having properties as an epoxy resin curing agent, and have completed the present invention.

That is, the present invention provides a silica-titania composite oxide characterized by having the following physical properties.

(1) BET specific surface area of 25 to 60 m ² /g
(2) The amount of acid with a pKa of 4.1 or less is 0.10 μmol/m ² or more

According to the present invention, there is provided a silica-titania composite oxide that can be used as a curing agent for curing an epoxy resin, and that can reduce the coefficient of linear expansion of the cured epoxy resin and improve the reliability of the cured product. can be done.

Weight-based particle size distribution of silica-titania composite oxide obtained in Example 1 Weight-based particle size distribution of silica-titania composite oxide obtained in Example 2 Weight-based particle size distribution of silica-titania composite oxide obtained in Example 3 Weight-based particle size distribution of silica obtained in Comparative Example 1 Weight-based particle size distribution of titanium oxide used in Comparative Example 2

The silica-titania composite oxide of the present invention is
(1) a BET specific surface area of 25 to 60 m ² /g;
(2) the amount of acid with a pKa of 4.1 or less is 0.1 μmol/m ² or more;
It has the physical property of

(1) BET Specific Surface Area The BET specific surface area of the silica-titania composite oxide of the present invention is 25 to 60 m ² /g as determined by the nitrogen adsorption BET single-point method. If it is less than 25 m ² /g, it means that the contribution of the acid sites on the particle surface is small, the curing reaction of the epoxy resin does not proceed, and it is the same as a commonly used filler. If it exceeds 60 m ² /g, it becomes difficult to fill the epoxy resin at a high level, and it is difficult to obtain the effect of a filler that lowers the coefficient of linear expansion of the cured product. More preferably, it is 25 to 40 m ² /g.

(2) Acid amount with a pKa of 4.1 or less The silica-titania composite oxide of the present invention has an acid amount with a pKa of 4.1 or less, which is specified by an amine titration method using bromophenol blue as an indicator, and is 0.1 μmol/m ² or more. is. If it is less than 0.1 μmol/m ² , it means that the solid acidity of the particles is weak, and the epoxide ring-opening reaction by the acid catalyst does not proceed, so that the effect as a curing agent is not sufficiently obtained, and the epoxy resin curing reaction does not occur. Difficult to proceed. More preferably, it is 0.15 μmol/m ² or more.

In addition, in the silica-titania composite oxide, there may be acid sites with a pKa of 1.7 or less among the acid sites with a pKa of 4.1 or less. The acid site acting as a curing agent may have a pKa of 4.1 or less, and the amount of the acid site having a pKa of 1.7 or less does not matter.

Further, acid sites with a pKa exceeding 4.1 are generally present, but such acid sites do not substantially contribute to the action of the epoxy resin as a curing agent.

The silica-titania composite oxide of the present invention, which satisfies the physical properties (1) specific surface area and (2) acid content, functions as both a curing agent and a filler as a filler for curing epoxy resins.

The silica-titania composite oxide of the present invention should have the physical properties described above, but preferably further has the following physical properties.

The primary particles of the silica-titania composite oxide of the present invention are preferably spherical from the standpoints of improving filling properties into epoxy resins and improving fluidity. More specifically, using a scanning electron microscope (SEM), an observed SEM image is obtained, and the value C (circularity) defined by the following formula (1) for each particle is obtained by image analysis. The average circularity calculated as an arithmetic mean value of 2000 or more particles is preferably 0.8 or more.

C=4πS/L ²
[In formula (1), S represents the area (projected area) of the particle in the image. L represents the length (perimeter) of the outer periphery of the particle in the image. ]

Furthermore, since scattering by particles also affects transparency, the silica-titania composite oxide of the present invention has a median diameter (cumulative 50% weight diameter: hereinafter, D ₅₀ ) is preferably in the range of 50 to 200 nm.

Furthermore, the silica-titania composite oxide of the present invention is preferably polydisperse particles in terms of filling properties into epoxy resins. Specifically, in the relationship between the D ₅₀ and the cumulative 90% by weight diameter (hereinafter referred to as D ₉₀ ), (D ₉₀ −D ₅₀ )/D ₅₀ is preferably in the range of 0.3 to 0.5. .

Furthermore, the silica-titania composite oxide of the present invention has a refractive index in the range of 1.50 to 1.60 at a wavelength of 589 nm (D line of sodium) in that transparency can be exhibited by matching the refractive index of the epoxy resin. preferably in

The refractive index changes depending on the ratio of Ti (Ti molar ratio). That is, based on the refractive index of silica (SiO ₂ ) of 1.46, it increases as the proportion of TiO ₂ increases. Therefore, in order to easily obtain the above refractive index, the ratio of Ti (Ti molar ratio) is preferably 4 to 17 mol%, particularly 5 to 17 mol%, when the total of Si and Ti is 100 mol%. Preferably.

In addition, the silica-titania composite oxide of the present invention is amorphous in crystal form in that the refractive index changes in the particles when silica and titania undergo phase separation, and cloudiness occurs when filled in epoxy resin ( No peaks are detected by X-ray diffraction).

Furthermore, the silica-titania composite oxide of the present invention preferably does not have photocatalytic activity in order to prevent decomposition and deterioration of the resin due to photocatalytic action.

Moreover, when it exists as powder, it is more preferable that the color tone is visually white.

(Method for producing silica-titania composite oxide)
The method for producing the silica-titania composite oxide of the present invention having the properties as described above is not particularly limited. can be manufactured by

The siloxane compound may be any vaporizable compound, and specific examples thereof include hydrocarbon group-substituted siloxanes such as hexamethyldisiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane. be done. Titanium alkoxides include tetramethoxytitanium, tetraethoxytitanium, tetra-i-propoxytitanium, tetra-n-propoxytitanium, tetra-n-butoxytitanium, tetra-s-butoxytitanium, tetra-t-butoxytitanium, and the like. Organotitanium compounds may be mentioned. One or more of the siloxane compounds and one or more of the titanium alkoxides may be mixed and used.

According to this production method, the Ti molar ratio in the raw material mixture substantially matches the Ti molar ratio in the produced silica-titania composite oxide, so the mixing ratio of the siloxane compound and the titanium alkoxide matches the desired value. Thus, the Si content and the Ti content in each compound should be taken into consideration. However, since some deviation may occur, it is desirable to confirm and determine the Ti molar ratio in the manufactured silica-titania composite oxide by XRF or the like.

In the method utilizing a combustion reaction of a mixture of a siloxane compound and a titanium alkoxide, the shape of the burner to be used is not particularly limited, but a concentric multi-tube burner is preferred in terms of ease of ignition and combustion stability. A concentric multi-tube burner consists of a center and a plurality of annular tubes radiating concentrically from the center tube.

The method using a concentric triple-tube burner consisting of a central tube and two annular tubes will be described in detail below.

Vaporized siloxane compound, titanium alkoxide and oxygen are mixed in advance and introduced into the central tube of the triple tube burner. At this time, an inert gas such as nitrogen may be mixed in addition to siloxane, titanium alkoxide and oxygen. Alternatively, air may be used as the oxygen source.

The amount of oxygen to be mixed is RO = (the amount of oxygen mixed with the siloxane compound and titanium alkoxide) / (the amount of oxygen stoichiometrically required for complete combustion of the siloxane compound and titanium alkoxide), and _O2 concentration = ( The amount of oxygen introduced into the central tube)/(the amount of oxygen introduced into the central tube + the amount of nitrogen introduced into the central tube) can be used as an index for adjustment.

More strictly, the above RO is defined by the following formula (1).

RO= _NO0 / _NDO0 formula (1)
N _O0 : Amount of oxygen introduced into central canal (Nm ³ /h)
N _DO0 : Amount of oxygen (Nm ³ /h) required for stoichiometric complete combustion of combustible substances introduced into the central tube

The above N _DO0 defines the amounts of combustible substances introduced into the central tube, specifically the siloxane compound and titanium alkoxide, as follows, and is required depending on the chemical structures of the siloxane compound and titanium alkoxide. It can be calculated by using the oxygen content as a coefficient.

N _S : Amount of siloxane introduced into the central tube (Nm ³ /h)
N _T : Amount of titanium alkoxide introduced into the central tube (Nm ³ /h)

For example, if the siloxane compound is octamethylcyclotetrasiloxane, the compound is C ₈ H ₂₄ O ₄ Si ₄ , so stoichiometrically complete combustion is 8CO ₂ +12H ₂ O + 4SiO ₂ , thus the amount of oxygen required ( _O2 amount) is 16 molar times. Further, when the titanium alkoxide is tetra-i-propoxytitanium, the amount of oxygen required for complete combustion is 18 moles. Therefore, when these compounds are used as raw materials, _NDO0 is as follows.

_NDO0 = 16N _S + 18N _T

Since _NDO0 is the amount of oxygen required to completely burn all combustible substances introduced into the central tube, if a combustible gas other than a siloxane compound and titanium alkoxide is introduced, its contribution should also be considered. There is a need. For example, when hydrogen gas is introduced, it is as follows.

RO= _NO0 / _NDO = _NO0 /( _16NS + _18NT + _0.5NHO )
N _H0 : Amount of hydrogen introduced into the central tube (Nm ³ /h)

When producing the silica-titania composite oxide of the present invention, the above RO is set to 0.2 or more. If RO is less than 0.2, unburned raw material occurs.

Also, the O ₂ concentration is set to 80% or less. If the O ₂ concentration is greater than 80%, flame flashback may occur, resulting in unstable combustion.

A combustible gas such as hydrogen or hydrocarbon is introduced into the first annular tube outside the central tube to form an auxiliary combustion flame. At this time, an inert gas such as nitrogen and/or a combustion supporting gas such as oxygen may be mixed. The amount of combustible gas in the first annular tube may be set as appropriate as long as it can form a flame, and unlike the composition in the central tube, it does not affect the physical properties of the resulting silica-titania composite oxide. From the viewpoint of easily forming a stable flame, it is desirable to set the auxiliary fuel ratio R _SFL defined by the following formula to 0.005 to 0.5. If it is larger than 0.5, there is no particular effect and it is economically disadvantageous. If it is less than 0.005, combustion becomes unstable and no flame is formed.

R _SFL =N _DO1 /N _DO0
N _DO1 : Amount of oxygen (Nm ³ /h) required for stoichiometric and complete combustion of combustible substances introduced into the first annular pipe

For example, the combustible gas to be introduced into the first annular pipe is hydrogen gas, and the amount introduced is _NH1 : Amount of hydrogen introduced into the first annular pipe (Nm ³ /h)
, N _DO1 becomes 0.5N _H1 . When the siloxane compound is octamethylcyclotetrasiloxane and the titanium alkoxide is tetra-i-propoxytitanium,
R _SFL =0.5 N _H1 /N _DO0
=0.5N _H1 /(16N _S +18N _T +0.5N _H0 )
=N _H1 /(32N _S +36N _T +N _H0 )
becomes.

A combustion-supporting gas such as oxygen is introduced into a second annular tube outside the first annular tube to form a combustion-assisting flame. At this time, an inert gas such as nitrogen may be mixed. The amount of the combustion-supporting gas in the second annular tube may be set appropriately as long as it can form a flame, and unlike the composition in the central tube, it does not affect the physical properties of the resulting silica-titania composite oxide. , the combustion-supporting oxygen ratio R _cmbts defined by the following formula is preferably 0.1 to 2.0. If it is greater than 2.0, there is no particular effect and it is economically disadvantageous. If it is less than 0.1, combustion becomes unstable and no flame is formed.

R _cmbts =N _O2 /N _DO0
NO2 : Amount of oxygen introduced into the second annular pipe ( ^Nm3 /h)
= 0.21 x second annular pipe introduced air amount (Nm ³ /h)

The silica-titania composite oxide produced as described above may be separated from the combustion gas by filter separation using a metal filter, ceramic filter, bag filter or the like, or centrifugal separation using a cyclone or the like, and recovered.

According to the manufacturing method described above, not only the specific surface area and the acid amount but also other physical properties are usually within the ranges described above.

Furthermore, the silica-titania composite oxide produced by the above method is non-porous, and its density substantially agrees with the theoretical value. That is, the numerical value calculated using the Ti molar ratio with the density of silica (SiO ₂ ) being 2.2 g/cm ³ and the density of titania (TiO ₂ ) being 3.9 g/cm ³ agrees with the measured value.

The silica-titania composite oxide of the present invention produced as described above can be mixed with an epoxy resin as it is, but it can also be used after being surface-treated with a surface treatment agent.

That is, the silica-titania composite oxide of the present invention can be used on the surfaces of silylating agents, silicone oils, siloxanes, metal alkoxides, fatty acids and metal salts thereof, etc., as long as the physical properties after treatment satisfy the surface area and acid amount described above. It may be surface-treated with a treating agent.

Specific silylating agents include tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane, n-butyltrimethoxysilane, Methoxysilane, i-butyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyl diethoxysilane, i-butyltriethoxysilane, decyltriethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2 -aminoethyl)aminopropylmethyldimethoxysilane, hexamethyldisilazane, hexaethyldisilazane, hexapropyldisilazane, hexabutyldisilazane, hexapentyldisilazane, hexahexyldisilazane, hexacyclohexyldisilazane , hexaphenyldisilazane, divinyltetramethyldisilazane, dimethyltetravinyldisilazane, and the like.

Examples of silicone oils include dimethyl silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, alkyl-modified silicone oil, fatty acid-modified silicone oil, polyether-modified silicone oil, alkoxy-modified silicone oil, carbinol-modified silicone oil, amino Examples include modified silicone oil and terminal reactive silicone oil.

Examples of siloxanes include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane, octamethyltrisiloxane, and the like.

Examples of metal alkoxides include trimethoxyaluminum, triethoxyaluminum, tri-i-propoxyaluminum, tri-n-butoxyaluminum, tri-s-butoxyaluminum, tri-t-butoxyaluminum, mono-s-butoxydi-i -propylaluminum, tetramethoxytitanium, tetraethoxytitanium, tetra-i-propoxytitanium, tetra-n-propoxytitanium, tetra-n-butoxytitanium, tetra-s-butoxytitanium, tetra-t-butoxytitanium, tetraethoxyzirconium , tetra-i-propoxyzirconium, tetra-n-butoxyzirconium, dimethoxytin, diethoxytin, di-n-butoxytin, tetraethoxytin, tetra-i-propoxytin, tetra-n-butoxytin, diethoxyzinc, magnesium methoxide, magnesium ethoxide, magnesium isopropoxide and the like.

Furthermore, further specific examples of fatty acids and metal salts thereof include undecylic acid, lauric acid, tridecylic acid, dodecylic acid, myristic acid, palmitic acid, pentadecylic acid, stearic acid, heptadecylic acid, arachidic acid, montanic acid, and olein. acid, linoleic acid, arachidonic acid, and the like, and metal salts thereof include salts with metals, such as zinc, iron, magnesium, aluminum, calcium, sodium, and lithium.

As for the method of surface treatment using the surface treatment agent, known methods can be used without any limitation. For example, a common method is to spray the surface treatment agent while stirring the silica-titania composite oxide, or vaporize it and contact it as a vapor.

According to known general surface treatment methods, the specific surface area after treatment is the same or slightly lower, and by appropriately controlling the amount of the treatment agent used, the surface can be treated while leaving acid sites. can be done.

In the case where the action of the epoxy resin in the silica-titania composite oxide of the present invention as a curing agent is not utilized, the amount of acid after surface treatment may be less than the above value.

(Usage))
The silica-titania composite oxide of the present invention acts as a curing agent for epoxy resins. Therefore, it can be suitably used as a filler and curing agent in an epoxy resin composition.

The type of the epoxy resin is not particularly limited, but an oligomer or polymer epoxy resin having two or more epoxy groups in one molecule is suitable. For example, bisphenyl-type epoxy resin, stilbene-type epoxy resin, bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, triphenolmethane-type epoxy resin, alkyl-modified triphenolmethane-type epoxy resin, dicyclopentadiene-modified phenol-type epoxy resin, Naphthol-type epoxy resins, triazine nucleus-containing epoxy resins, and the like can be mentioned. One of these may be used alone, or a plurality of them may be used in combination.

In the case of forming an epoxy resin composition, each component such as a known curing agent, curing accelerator, and additive may be added to improve the performance of the cured product.

Such an epoxy resin composition can be used in the same applications as known epoxy resin compositions, such as a semiconductor sealing material.

In the case of an epoxy resin composition, the amount of the silica-titania composite oxide of the present invention can be appropriately selected and determined from a known range according to its application, but generally it is 30 to 30% of the total composition. 85 mass %, mostly 40-75 mass %.

Furthermore, the silica-titania composite oxide of the present invention can also be used simply as a filler for other resin compositions without utilizing its action as a curing agent for epoxy resins. In this case, it may be used in the same manner as known silica-titania composite oxides. Specifically, it can be used as a filler for (meth)acrylic resins, polyester resins, silicone resins, polycarbonate resins, and olefinic resins.

Examples of the present embodiment will be described below in detail, but the present invention is not limited to these examples.

Various physical property measurements and the like in the following examples and comparative examples are based on the following methods.

(1) BET specific surface area A BET specific surface area measuring device (SA-1000 manufactured by Shibata Kagaku Co., Ltd.) was used to measure the specific surface area (m ² /g) by the nitrogen adsorption BET one-point method.

(2) XRF
The silica content and titania content in the particles were measured using a fluorescent X-ray spectrometer (ZSX Primus IV manufactured by Rigaku Corporation). The content was calculated assuming that the total of the obtained Si content and Ti content was 100 mol %.

(3) Acid content The acid content of the particles was determined as the total acid content of Lewis acid and Bronsted acid, and was measured as follows by an amine titration method using methyl red, bromophenol blue, and thymol blue as indicators.

0.5 g of particles and 20 mL of benzene (reagent special grade, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were weighed into a glass sample vial (manufactured by AS ONE Corporation, content: 30 ml, outer diameter: about 28 mm). This sample vial was placed in an ultrasonic cell disrupter (BRANSON Sonifier SFX250, probe: 1/4 inch) so that the lower surface of the probe tip was 15 mm below the liquid surface, and dispersed for 3 minutes at an output of 20 W. A liquid was prepared.

To this dispersion, 0.1 mL of a solution obtained by diluting methyl red (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to 0.1% by weight with benzene was added and mixed by hand shaking, and after standing for 1 hour, butylamine (Fujifilm Wako Pure Chemical Industries, Ltd.) Wako special grade manufactured by Yakusha) was titrated with a solution diluted with benzene to 0.05 mol/L. The endpoint of the titration was the point at which the color of the dispersion changed from red to yellow. The amount of acid at pKa 4.8 (mmol/g) was obtained from the titration amount of butylamine, and the amount of acid per unit surface area (μmol/m ² ) calculated from the specific surface area of the target was defined as the amount of acid at pKa 4.8 or less.

Bromophenol blue (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) and thymol blue (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were used as the indicators for titration in the same manner. The endpoint of the titration was the point at which the color of the dispersion changed from yellow to blue for bromophenol blue, and the point at which the color of the dispersion changed from red to yellow for thymol blue. As an indicator, bromophenol blue was used as an acid amount (μmol/m ² ) with a pKa of 4.1 or less, and thymol blue was used as an acid amount (μmol/m ² ) with a pKa of 1.7 or less.

(4) Carbon content Carbon content was measured using a combustion method elemental analyzer (Sumigraph NC-22F manufactured by Sumika Chemical Analysis Service, Ltd.). The amount of sample to be measured was 50 to 100 mg.

(5) Photocatalytic activity The acetaldehyde removal rate by photocatalytic activity was evaluated using relaxed conditions of the acetaldehyde air purification performance test (JIS R 1701-2). A test piece was prepared by weighing 200 mg of a powder sample on a frosted glass (49×99 mm), spreading it with distilled water, and drying it naturally. Two specimens were used for the test due to the relaxed conditions.

(6) XRD Measurement The crystal structure was measured using an X-ray diffractometer (smartLab manufactured by Rigaku Corporation). The measurement conditions were CuKα rays, scanning range 2θ=10 to 90°, scanning speed 1°/min, and step width 0.02°.

(7) Particle size distribution (Preparation of measurement sample)
An aqueous suspension with a particle concentration of 0.25% by mass, which is a measurement sample, was prepared as follows. 0.05 g of particles and 20 ml of distilled water were placed in a glass sample tube bottle (manufactured by AS ONE Corporation, content 30 ml, outer diameter of about 28 mm), and an ultrasonic cell disrupter (BRANSON Sonifier II Model 250D, probe: 1/ A sample vial containing the sample was placed so that the lower surface of the probe tip of 4 inches) was 15 mm below the water surface, and the particles were dispersed in distilled water under the conditions of an output of 20 W and a dispersion time of 3 minutes. A 25% by weight aqueous suspension was prepared.

(Particle size distribution measurement)
CPS Instruments Inc. The weight-based particle size distribution was measured using a disc centrifugal particle size distribution analyzer (DC24000) manufactured by The measurement conditions were rotation speed of 18000 rpm, temperature of 32° C., true density of silica and silica-titania of 2.2 g/cm ³ , and true density of titania of 3.9 g/cm ³ . Since the ratio of titania in the silica-titania produced in each example is relatively small, even if the true density is 2.2 g/cm ³ , the results are within the error range.

_D10 , _{D25, D50, D75 and D90 were} calculated from the obtained weight-based particle size distribution. 10 weight percent cumulative diameter, 25 weight percent cumulative diameter, median diameter (50 weight percent cumulative), 75 weight percent cumulative diameter, and 90 weight percent cumulative diameter, respectively.

(8) Epoxy resin curing properties (Preparation of epoxy resin composition)
100 parts by weight of particles were mixed with 100 parts by weight of bisphenol A+F type epoxy resin (ZX-1059, manufactured by Nippon Steel Chemical & Material Co., Ltd.) and kneaded by hand. After that, using a rotation-revolution mixer (Awatori Mixer AR-500, manufactured by Thinky), the mixture was stirred at a rotation speed of 1000 rpm for 8 minutes, and then degassed at a rotation speed of 2000 rpm for 2 minutes to knead the epoxy resin. A composition was obtained.

(Evaluation of resin curing characteristics)
The epoxy resin composition was heated in a constant temperature bath at 120° C. and 150° C., and the time from the start of heating to gelation was measured. In addition, regarding the resin curing properties, <0.5 indicates that the resin has already gelled 30 minutes after heating, and >24 indicates that it does not gel after 24 hours.

Example 1
Using octamethylcyclotetrasiloxane as a siloxane compound and tetra-i-propoxytitanium as a titanium alkoxide as raw materials, they were burned with a triple tube burner under the following conditions to produce a silica-titania composite oxide.

Octamethylcyclotetrasiloxane and tetra-i-propoxytitanium were mixed so that the Ti molar ratio was 5.0, heat-vaporized, mixed with oxygen and nitrogen, and introduced into the central tube at 473K. The ratio of each gas was adjusted so that the central tube had an RO of 0.7 and an O ₂ concentration of 30 vol %.

Hydrogen and nitrogen were introduced into the first annular tube at 423K such that the R _SFL was 0.26 and the volume ratio was 1.4:1. Air was introduced into the second annular tube at 423K in an amount to give an R _cmbts of 0.52. These conditions are shown in Table 1. The RDT in the table is defined below, and is 1 when no combustible substances other than siloxane compounds and titanium alkoxide are introduced into the central tube, and when other combustible substances are included, the ratio takes a value less than 1 depending on

RDT= _NDOM / _NDO0
N _DOM : Amount of oxygen (Nm ³ /h) required for stoichiometric complete combustion of the siloxane compound and titanium alkoxide introduced into the central tube
Table 1 shows the physical properties of the particles obtained under the above conditions and the resin curing properties.

Examples 2-3 and Comparative Example 1
Particles were produced in the same manner as in Example 1, except that the production conditions were changed as shown in Table 1. Each evaluation result is shown in Table 1.

Example 4
After 100 parts by weight of the silica-titania composite oxide obtained in the same manner as in Example 2 was put into the surface treatment reactor, the temperature was raised to 250° C. while replacing with nitrogen. After that, the reactor was closed and 0.4 parts by weight of steam was introduced. Then, 4 parts by weight of hexamethyldisilazane was added. After maintaining for 1 hour and performing nitrogen substitution, the mixture was cooled to room temperature to obtain a hydrophobized silica-titania composite oxide having trimethylsilyl groups introduced on the surface. Each evaluation result is shown in Table 1.

Comparative example 2
Titanium (IV) oxide, anatase type (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., Wako first class) was used. Resin curing properties are shown in Table 1.

Furthermore, regarding the weight-based particle size distribution measured by the disc centrifugal particle size distribution measuring device, FIG. 1 shows Example 1, FIG. 2 shows Example 2, FIG. 3 shows Example 3, and FIG. , and the particle size distribution of Comparative Example 2 is shown in FIG.

From these examples, it can be seen that the silica-titania composite oxide particles are fillers that can be used as curing agents for epoxy resins. Moreover, even if the surface treatment is performed, it can be seen that there is an effect as a curing agent as long as it satisfies both physical properties of specific surface area and acid content.

Claims (4)

A silica-titania composite oxide characterized by having the following physical properties.
(1) BET specific surface area of 25 to 60 m ² /g
(2) The amount of acid with a pKa of 4.1 or less is 0.1 μmol/m ² or more A silica-titania composite oxide having the following relationship between the cumulative 50% weight diameter (D ₅₀ ) and the cumulative 90% weight diameter (D ₉₀ ) calculated from the weight-based particle size distribution obtained by centrifugal sedimentation.
0.3 ≤ (D ₉₀ −D ₅₀ )/D ₅₀ ≤ 0.5 A resin composition containing the silica-titania composite oxide according to claim 1 or 2 and an epoxy resin. A semiconductor sealing material comprising the resin composition according to claim 3 .

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