Silica-titania mixed oxide

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

[Technical Field]

[0001] The present invention relates to a novel silica-titania composite oxide, specifically to a silica-titania composite oxide that can be used as a curing agent for epoxy resins and as a filler that can reduce the linear expansion coefficient of a cured epoxy resin and thereby improve the reliability of the cured epoxy resin. [Background technology]

[0002] Epoxy resins are used in a variety of applications, such as adhesives, sealants, and coatings.

[0003] In general, a curing agent or a curing accelerator is added to an epoxy resin as a component for promoting the curing reaction.

[0004] Epoxy resins are also used as semiconductor encapsulants. For example, in flip-chip packages, they are used as underfill agents to protect the connected semiconductor chip, wiring board, and bumps. Because the epoxy resin, semiconductor chip, and wiring board each have different linear expansion coefficients, cracks can occur at the connection if the connection cannot absorb stress. To prevent this cracking, underfill agents are mixed with fillers with a relatively low linear expansion coefficient, such as silica.

[0005] In recent years, underfill agents have been made with not only epoxy resins, curing agents, and fillers, but also various additives to improve the performance of the cured product (see, for example, Patent Documents 1 and 2). In order to simplify the manufacturing process, there is a demand for materials with multiple properties, such as fillers that can be used as curing agents. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-135429 [Patent Document 2] Japanese Patent Application Publication No. 2020-186397 Summary of the Invention [Problem to be solved by the invention]

[0007] 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 linear expansion coefficient of a cured epoxy resin material and improve the reliability of the cured material. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to achieve the above object, and as a result have found that a silica-titania composite oxide having strong solid acidity can be used as a filler having properties that act as an epoxy resin curing agent, which has led to the completion of the present invention.

[0009] That is, the present invention provides a silica-titania composite oxide characterized by having the following physical properties: A curing agent for epoxy resins comprising is.

[0010] (1) BET specific surface area is 25 to 60 m 2 / g (2) The acidity of pKa 4.1 or less is 0.10 μmol / m 2 End [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a silica-titania composite oxide that can be used as a curing agent for curing epoxy resins, and that can reduce the linear expansion coefficient of a cured epoxy resin material and improve the reliability of the cured material. [Brief explanation of the drawings]

[0012] [Figure 1] Weight-based particle size distribution of silica-titania composite oxide obtained in Example 1 [Figure 2] Weight-based particle size distribution of silica-titania composite oxide obtained in Example 2 [Figure 3] Weight-based particle size distribution of silica-titania composite oxide obtained in Example 3 [Figure 4] Weight-based particle size distribution of silica obtained in Comparative Example 1 [Figure 5] Weight-based particle size distribution of titanium oxide used in Comparative Example 2 DETAILED DESCRIPTION OF THE INVENTION

[0013] The silica-titania composite oxide of the present invention is (1) BET specific surface area is 25 to 60 m 2 / g, (2) The acidity of pKa 4.1 or less is 0.1 μmol / m 2 That's all, It has the following physical properties.

[0014] (1)BET specific surface area The BET specific surface area of ​​the silica-titania composite oxide of the present invention is determined by the nitrogen adsorption BET single-point method and is in the range of 25 to 60 m 2 / g. 25m 2 If the ratio is less than 60m / g, it means that the contribution from the acid sites on the particle surface is small, and the curing reaction of the epoxy resin does not proceed, making it no different from a filler that is normally used. 2 If it is greater than 25 to 40 m / g, it becomes difficult to highly fill the epoxy resin, and it is difficult to achieve the effect of the filler in reducing the linear expansion coefficient of the cured product. 2 / g.

[0015] (2) Acidity of pKa 4.1 or less The acid amount of the silica-titania composite oxide of the present invention having a pKa of 4.1 or less is determined by an amine titration method using bromophenol blue as an indicator, and is 0.1 μmol / m 2 That's it. 0.1 μmol / m 2 If the content is less than 0.15 μmol / m, the solid acidity of the particles is weak, and the epoxide ring-opening reaction by the acid catalyst does not proceed, so the effect as a curing agent is not fully exhibited and the epoxy resin curing reaction does not proceed easily. 2 That's all.

[0016] In silica-titania composite oxides, some of the acid sites with a pKa of 4.1 or less have acid sites with a pKa of 1.7 or less. However, according to the investigations of the present inventors, the acid sites that function as a curing agent for epoxy resins only need to have a pKa of 4.1 or less, and the acid sites with a pKa of 1.7 or less may exist in any quantity.

[0017] Furthermore, although acid sites with a pKa of more than 4.1 are generally present, such acid sites do not substantially contribute to the action of the epoxy resin as a curing agent.

[0018] The silica-titania composite oxide of the present invention, which satisfies the above physical properties (1) specific surface area and (2) acid amount, plays the roles of both a curing agent and a filler when used as a filler for curing epoxy resins.

[0019] The silica-titania composite oxide of the present invention may have the above physical properties, but preferably has the following additional physical properties.

[0020] From the viewpoint of improving filling properties in epoxy resins, improving fluidity, etc., it is preferable that the silica-titania composite oxide of the present invention has spherical primary particles. More specifically, an SEM image is obtained by observation using a scanning electron microscope (SEM), and the value C (circularity) defined by the following formula (1) is determined for each particle by image analysis. The average circularity calculated as the arithmetic mean of the circularity C for 2,000 or more particles is preferably 0.8 or more.

[0021] C=4πS / L 2 [In formula (1), S represents the area (projected area) that the particle occupies in the image, and L represents the length (perimeter) of the outer periphery of the particle in the image.]

[0022] Furthermore, since the scattering of particles also affects the transparency, the silica-titania composite oxide of the present invention has a median diameter (cumulative 50% weight diameter: hereinafter referred to as D50 ) is preferably in the range of 50 to 200 nm.

[0023] Furthermore, in terms of filling properties into epoxy resins, the silica-titania composite oxide of the present invention is preferably polydisperse particles. 50 and the cumulative 90% diameter (hereinafter referred to as D 90 ) in the relationship (D 90 -D 50 ) / D 50 is preferably in the range of 0.3 to 0.5.

[0024] Furthermore, since transparency can be exhibited by matching the refractive index with that of the epoxy resin, the refractive index of the silica-titania composite oxide of the present invention at a wavelength of 589 nm (sodium D line) is preferably in the range of 1.50 to 1.60.

[0025] The refractive index varies depending on the proportion of Ti (Ti molar ratio). That is, starting from the refractive index of silica (SiO2) of 1.46, the refractive index increases as the proportion of TiO2 increases. Therefore, in order to easily obtain the above refractive index, the proportion of Ti (Ti molar ratio) is preferably 4 to 17 mol%, and particularly preferably 5 to 17 mol%, when the total of Si and Ti is 100 mol%.

[0026] Furthermore, when silica and titania are phase-separated, the refractive index changes within the particles, causing cloudiness when filled into an epoxy resin. Therefore, it is preferable that the silica-titania composite oxide of the present invention has an amorphous crystal form (no peaks are detected by X-ray diffraction).

[0027] Furthermore, in order to prevent decomposition and deterioration of resins due to photocatalytic action, it is preferable that the silica-titania composite oxide of the present invention does not have photocatalytic activity.

[0028] When present as a powder, it is more preferable that the color tone is white when visually observed.

[0029] (Method of producing silica-titania composite oxide) The method for producing the silica-titania composite oxide of the present invention having the above-mentioned properties is not particularly limited, but according to the investigations of the present inventors, it can be produced by a method utilizing the combustion reaction of a mixture of a siloxane compound and a titanium alkoxide.

[0030] The siloxane compound may be any vaporizable compound, and specific examples include hydrocarbon-substituted siloxanes such as hexamethyldisiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane. Examples of titanium alkoxides include organic titanium compounds such as tetramethoxytitanium, tetraethoxytitanium, tetra-i-propoxytitanium, tetra-n-propoxytitanium, tetra-n-butoxytitanium, tetra-s-butoxytitanium, and tetra-t-butoxytitanium. One or more of the above siloxane compounds can be mixed with one or more of the above titanium alkoxides.

[0031] According to this manufacturing method, the Ti molar ratio in the raw material mixture is approximately equal to the Ti molar ratio in the produced silica-titania composite oxide, so the mixing ratio of the siloxane compound and titanium alkoxide can be adjusted to match the target value, taking into account the Si content and Ti content of each compound. However, since slight deviations may occur, it is desirable to confirm and determine the Ti molar ratio in the produced silica-titania composite oxide using XRF or the like.

[0032] In the method utilizing the combustion reaction of a mixture of a siloxane compound and a titanium alkoxide, the shape of the burner used is not particularly limited, but a concentric multi-tube burner is preferred in terms of ease of ignition, combustion stability, etc. A concentric multi-tube burner is composed of a center and multiple annular tubes extending concentrically from the center tube.

[0033] The method using a concentric triple-tube burner consisting of a central tube and two annular tubes is described in detail below.

[0034] A mixture of vaporized siloxane compound, titanium alkoxide, and oxygen is introduced into the central tube of the triple-tube burner. In addition to the siloxane, titanium alkoxide, and oxygen, an inert gas such as nitrogen may be mixed. Air may also be used as the oxygen source.

[0035] The amount of oxygen to be mixed can be adjusted using the following indicators: RO = (amount of oxygen mixed with the siloxane compound and titanium alkoxide) / (amount of oxygen required for the stoichiometric complete combustion of the siloxane compound and titanium alkoxide), and O2 concentration = (amount of oxygen introduced into the central tube) / (amount of oxygen introduced into the central tube + amount of nitrogen introduced into the central tube).

[0036] More precisely, the RO is defined by the following formula (1).

[0037] RO=N O0 / N DO0 Formula (1) N O0 : Amount of oxygen introduced into the central tube (Nm 3 / h) N DO0 : The amount of oxygen (Nm) required for the stoichiometric complete combustion of the combustible material introduced into the central tube 3 / h)

[0038] Above N DO0 can be calculated by defining the amount of combustible material introduced into the central tube, specifically the amount of siloxane compound and titanium alkoxide introduced, as follows, and using the amount of oxygen required, which depends on the chemical structure of the siloxane compound and titanium alkoxide, as a coefficient.

[0039] 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)

[0040] For example, if the siloxane compound is octamethylcyclotetrasiloxane, the compound is C8H 24Since the titanium alkoxide is O4Si4, its complete combustion stoichiometrically becomes 8CO2 + 12H2O + 4SiO2, so the amount of oxygen (O2) required is 16 times by mole. Also, when the titanium alkoxide is tetra-i-propoxytitanium, the amount of oxygen required for complete combustion is 18 times by mole. Therefore, when these compounds are used as raw materials, the amount of N DO0 becomes:

[0041] N DO0 =16N S +18N T

[0042] Furthermore, N DO0 is the amount of oxygen required to completely combust all of the combustible materials introduced into the central tube, so if a combustible gas other than the siloxane compound and titanium alkoxide is introduced, its contribution must also be taken into consideration. For example, if hydrogen gas is introduced, the following occurs:

[0043] RO=N O0 / N DO =N O0 / (16N S +18N T +0.5N H0 ) N H0 : Amount of hydrogen introduced into the central tube (Nm 3 / h)

[0044] When producing the silica-titania composite oxide of the present invention, the RO is set to 0.2 or more. If the RO is less than 0.2, the raw materials will remain unburned.

[0045] In addition, the O2 concentration should be 80% or less. If the O2 concentration is greater than 80%, there is a risk of flame backfire and unstable combustion.

[0046] In the first annular tube located outside the central tube, a combustible gas such as hydrogen or hydrocarbon is introduced to form a combustion-supporting 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 appropriately as long as it is sufficient to form a flame. Unlike the composition in the central tube, it does not affect the physical properties of the resulting silica-titania composite oxide, but it is preferable to use an auxiliary fuel ratio R defined by the following formula in order to easily form a stable flame. SFL It is desirable that the ratio be between 0.005 and 0.5. If it is greater than 0.5, there is no particular effect and it is economically disadvantageous. If it is less than 0.005, combustion becomes unstable and a flame does not form.

[0047] R SFL =N DO1 / N DO0 N DO1 : The amount of oxygen (Nm) required for the stoichiometric complete combustion of the combustible material introduced into the first annular pipe 3 / h)

[0048] For example, if the flammable gas introduced into the first annular pipe is hydrogen gas, the amount of the introduced gas is N H1 : Amount of hydrogen introduced into the first annular pipe (Nm 3 / h) If we define DO1 is 0.5N H1 Similarly to the above, when the siloxane compound is octamethylcyclotetrasiloxane and the titanium alkoxide is tetra-i-propoxytitanium, R SFL =0.5N H1 / N DO0 =0.5N H1 / (16N S +18N T +0.5N H0 ) =N H1 / (32N S +36N T +N H0 ) This becomes:

[0049] A combustion-supporting gas such as oxygen is introduced into the second annular pipe located outside the first annular pipe to form a combustion-supporting flame. At this time, an inert gas such as nitrogen may be mixed. The amount of the combustion-supporting gas in the second annular pipe may be set appropriately as long as it is sufficient to form a flame. Unlike the composition in the central pipe, it does not affect the physical properties of the resulting silica-titania composite oxide. However, the combustion-supporting oxygen ratio R defined by the following formula is required. cmbts It is desirable to supply the fuel so that the ratio is 0.1 to 2.0. If the ratio is greater than 2.0, there is no particular effect and it is economically disadvantageous. If the ratio is less than 0.1, the combustion becomes unstable and no flame is formed.

[0050] R cmbts =N O2 / N DO0 N O2 : Amount of oxygen introduced into the second annular pipe (Nm 3 / h) = 0.21 x Air volume introduced into the second annular pipe (Nm 3 / h)

[0051] 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 by centrifugal separation using a cyclone or the like, and then recovered.

[0052] According to the above-mentioned production method, not only the specific surface area and acid amount but also other physical properties usually fall within the above-mentioned ranges.

[0053] Furthermore, the silica-titania composite oxide produced by the above method is non-porous, and its density is almost the same as the theoretical value. 3 , the density of titania (TiO2) is 3.9 g / cm 3 The value calculated using the Ti molar ratio agrees with the measured value.

[0054] The silica-titania composite oxide of the present invention produced as described above can be mixed directly with an epoxy resin, but can also be surface-treated with a surface treatment agent before use.

[0055] That is, the silica-titania composite oxide of the present invention may be surface-treated with a surface treatment agent such as a silylating agent, silicone oil, siloxanes, metal alkoxides, fatty acids and metal salts thereof, as long as the physical properties after treatment satisfy the above-mentioned surface area and acid amount.

[0056] Specific silylating agents include tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane, n-butyltrimethoxysilane, i-butyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, i-butyltriethoxysilane, decyltriethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidyltriethoxy ... Examples of the silazane include alkoxysilanes such as dipropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and γ-(2-aminoethyl)aminopropylmethyldimethoxysilane; and silazanes such as hexamethyldisilazane, hexaethyldisilazane, hexapropyldisilazane, hexabutyldisilazane, hexapentyldisilazane, hexahexyldisilazane, hexacyclohexyldisilazane, hexaphenyldisilazane, divinyltetramethyldisilazane, and dimethyltetravinyldisilazane.

[0057] Examples of silicone oils include dimethyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, alkyl-modified silicone oil, fatty acid-modified silicone oil, polyether-modified silicone oil, alkoxy-modified silicone oil, carbinol-modified silicone oil, amino-modified silicone oil, and terminally reactive silicone oil.

[0058] Examples of siloxanes include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane, and octamethyltrisiloxane.

[0059] Furthermore, 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, and magnesium isopropoxide.

[0060] Further specific examples of fatty acids and their metal salts include long-chain fatty acids such as undecylic acid, lauric acid, tridecylic acid, dodecylic acid, myristic acid, palmitic acid, pentadecylic acid, stearic acid, heptadecylic acid, arachidic acid, montanic acid, oleic acid, linoleic acid, and arachidonic acid, and their metal salts include salts with metals such as zinc, iron, magnesium, aluminum, calcium, sodium, and lithium.

[0061] The surface treatment method using the surface treatment agent may be any known method without any limitation, for example, a method in which the surface treatment agent is sprayed onto the silica-titania composite oxide while stirring, or vaporized and brought into contact with the silica-titania composite oxide as vapor.

[0062] According to known general surface treatment methods, the specific surface area after treatment remains the same or is only slightly reduced, and by appropriately controlling the amount of treatment agent used, it is possible to perform surface treatment while leaving acid sites.

[0063] When the function of the silica-titania composite oxide of the present invention as a curing agent for epoxy resin is not utilized, the acid amount after surface treatment may be less than the above value.

[0064] (Application)) The silica-titania composite oxide of the present invention functions as a curing agent for epoxy resins, and can therefore be suitably used as a filler and curing agent in epoxy resin compositions.

[0065] The type of epoxy resin is not particularly limited, but preferred are oligomers or polymers having two or more epoxy groups per molecule. Examples include bisphenyl-type epoxy resins, stilbene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, triphenolmethane-type epoxy resins, alkyl-modified triphenolmethane-type epoxy resins, dicyclopentadiene-modified phenol-type epoxy resins, naphthol-type epoxy resins, and triazine-nucleus-containing epoxy resins. One of these may be used alone, or a mixture of two or more may be used.

[0066] When an epoxy resin composition is prepared, various components such as known curing agents, curing accelerators, and additives may be added to improve the performance of the cured product.

[0067] Such an epoxy resin composition can be used in the same applications as known epoxy resin compositions, for example, as a semiconductor encapsulant.

[0068] When an epoxy resin composition is prepared, the amount of the silica-titania composite oxide of the present invention can be appropriately selected from known ranges depending on the intended use, but is generally 30 to 85 mass % of the total composition, and often 40 to 75 mass %.

[0069] Furthermore, the silica-titania composite oxide of the present invention can be used simply as a filler for other resin compositions without utilizing its function as a curing agent for epoxy resins. In this case, it can 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, olefin-based resins, etc. [Example]

[0070] The present embodiment will be specifically described below with reference to examples, but the present invention is not limited to these examples in any way.

[0071] In the following examples and comparative examples, various physical properties were measured by the following methods.

[0072] (1) BET specific surface area Using a BET specific surface area measuring device (SA-1000 manufactured by Shibata Scientific Co., Ltd.), the specific surface area (m 2 / g) was measured.

[0073] (2) XRF The silica content and titania content in the particles were measured using a fluorescent X-ray analyzer (ZSX PrimusIV manufactured by Rigaku Corporation). The contents were calculated by taking the total of the obtained Si content and Ti content as 100 mol%.

[0074] (3) Acid amount The acid amount of the particles was the total acid amount 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.

[0075] 0.5 g of particles and 20 mL of benzene (special grade reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were weighed into a glass sample vial (manufactured by AS ONE Corporation, 30 mL capacity, approximately 28 mm outer diameter). This sample vial was placed in an ultrasonic cell disrupter (BRANSON Sonifier SFX250, 1 / 4 inch probe) so that the bottom of the probe tip was 15 mm below the liquid surface, and the mixture was dispersed at an output of 20 W for 3 minutes to prepare a dispersion.

[0076] To this dispersion, 0.1 mL of a solution of methyl red (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) diluted to 0.1 wt % with benzene was added and mixed by hand. After leaving to stand for 1 hour, it was titrated with a solution of butylamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Special Grade) diluted to 0.05 mol / L with benzene. The endpoint of the titration was the point at which the color of the dispersion changed from red to yellow. The acid amount (mmol / g) at pKa 4.8 was calculated from the titration amount of butylamine, and the acid amount per unit surface area (μmol / m) calculated from the specific surface area of ​​the target was used. 2 ) was defined as the amount of acid with a pKa of 4.8 or less.

[0077] The titration was carried out in the same manner, with the indicator changed to bromophenol blue (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and thymol blue (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). The end point of the titration was the point at which the color of the dispersion changed from yellow to blue for bromophenol blue, and from red to yellow for thymol blue. The titration was carried out using bromophenol blue as the indicator, with an acidity (μmol / m) of pKa 4.1 or less. 2 ) and thymol blue was used to measure the acid concentration (μmol / m 2 ) was decided.

[0078] (4) Carbon content The carbon content was measured using a combustion elemental analyzer (Sumigraph NC-22F manufactured by Sumika Chemical Analysis Center Co., Ltd.) The measurement sample amount was 50 to 100 mg.

[0079] (5) Photocatalytic activity The acetaldehyde removal rate by photocatalytic activity was evaluated using the relaxed conditions of the Acetaldehyde Air Purification Performance Test (JIS R 1701-2). A test piece was prepared by weighing 200 mg of powder sample onto a frosted glass (49 x 99 mm), spreading it with distilled water, and then air-drying it. Due to the relaxed conditions, two test pieces were used for the test.

[0080] (6)XRD measurement The crystal structure was measured using an X-ray diffractometer (Rigaku Corporation, smartLab) with CuKα radiation, a scan range of 2θ = 10 to 90°, a scan speed of 1° / min, and a step width of 0.02°.

[0081] (7) Particle size distribution (Preparation of measurement sample) A measurement sample, an aqueous suspension with a particle concentration of 0.25% by mass, was prepared as follows: 0.05 g of particles and 20 ml of distilled water were placed in a glass sample vial (manufactured by AS ONE Corporation, 30 ml capacity, approximately 28 mm outer diameter), and the vial containing the sample was placed so that the underside of the probe tip of an ultrasonic cell disrupter (BRANSON Sonifier II Model 250D, 1 / 4-inch probe) was 15 mm below the water surface. The particles were dispersed in distilled water at an output of 20 W for a dispersion time of 3 minutes to prepare a measurement sample aqueous suspension with a particle concentration of 0.25% by mass.

[0082] (Particle size distribution measurement) The weight-based particle size distribution was measured using a disc centrifugal particle size distribution analyzer (DC24000) manufactured by CPS Instruments Inc. The measurement conditions were a rotation speed of 18,000 rpm, a temperature of 32°C, and a true density of 2.2 g / cm for silica and silica-titania. 3 , the true density of titania is 3.9 g / cm 3 In addition, since the ratio of titania in the silica-titania produced in each example was relatively small, the true density was set to 2.2 g / cm 3 However, the results are within the margin of error.

[0083] From the weight-based particle size distribution obtained, D 10 and D25 and D 50 and D 75 and D 90 were calculated, which are the cumulative 10 wt% diameter, cumulative 25 wt% diameter, median diameter (cumulative 50 wt%), cumulative 75 wt% diameter, and cumulative 90 wt% diameter, respectively.

[0084] (8) Epoxy resin curing characteristics (Preparation of Epoxy Resin Composition) 100 parts by weight of bisphenol A+F type epoxy resin (ZX-1059, manufactured by Nippon Steel Chemical & Material Co., Ltd.) and 100 parts by weight of the particles were mixed and kneaded by hand. Then, using a planetary centrifugal mixer (Thinky Corporation, Awatori Rentaro AR-500), the mixture was stirred at 1000 rpm for 8 minutes, and then degassed at 2000 rpm for 2 minutes to obtain an epoxy resin composition.

[0085] (Resin curing characteristics evaluation) The epoxy resin compositions were heated in thermostatic chambers at 120°C and 150°C, and the time from the start of heating until gelation was measured. In terms of resin curing properties, those that had already gelled 30 minutes after heating were recorded as <0.5, and those that had not gelled within 24 hours were recorded as >24.

[0086] Example 1 Using octamethylcyclotetrasiloxane as the siloxane compound and tetra-i-propoxytitanium as the titanium alkoxide as raw materials, they were burned in a triple tube burner under the following conditions to produce silica-titania composite oxide.

[0087] Octamethylcyclotetrasiloxane and tetra-i-propoxytitanium were mixed so that the Ti molar ratio was 5.0, then heated and vaporized, mixed with oxygen and nitrogen, and introduced into the central tube at 473 K. The ratio of each gas was adjusted so that the RO in the central tube was 0.7 and the O2 concentration was 30 vol%.

[0088] The first annular pipe has R SFLHydrogen and nitrogen were introduced at 423 K so that the ratio of hydrogen to nitrogen was 0.26 and the volume ratio was 1.4:1. cmbts A quantity of air was introduced at 423 K such that the RDT was 0.52. These conditions are shown in Table 1. Note that RDT in the table is defined as follows: if no flammable substances other than the siloxane compound and titanium alkoxide are introduced into the central tube, it is 1; if other flammable substances are contained, it takes a value less than 1 depending on the proportion of those substances.

[0089] RDT=N DOM / N DO0 N DOM : The amount of oxygen (Nm) required for the stoichiometric complete combustion of the siloxane compound and titanium alkoxide introduced into the central tube 3 / h) The physical properties of the particles obtained under the above conditions and the resin curing characteristics are shown in Table 1.

[0090] Examples 2 to 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. The evaluation results are shown in Table 1.

[0091] Example 4 100 parts by weight of silica-titania composite oxide obtained in the same manner as in Example 2 was placed in a surface treatment reactor and heated to 250°C while purging with nitrogen. The reactor was then sealed, and 0.4 parts by weight of water vapor was introduced. Four parts by weight of hexamethyldisilazane was then added. The mixture was held for one hour, purged with nitrogen, and then cooled to room temperature to obtain a hydrophobic silica-titania composite oxide with trimethylsilyl groups introduced onto the surface. The evaluation results are shown in Table 1.

[0092] Comparative Example 2 Titanium oxide (IV), anatase type (Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1) was used. The resin hardening characteristics are shown in Table 1.

[0093] Furthermore, with regard to the weight-based particle size distribution measured by a disc centrifugal particle size distribution measuring device, the particle size distribution of Example 1 is shown in FIG. 1, that of Example 2 is shown in FIG. 3, that of Example 3 is shown in FIG. 4, and that of Comparative Example 1 is shown in FIG. 5.

[0094] [Table 1]

[0095] These examples demonstrate that silica-titania composite oxide particles are a filler that can be used as a curing agent for epoxy resins. Furthermore, even if surface-treated, they are effective as a curing agent as long as they satisfy both the specific surface area and acidity requirements.

Claims

1. A curing agent for epoxy resins comprising a silica-titania composite oxide, characterized by having the following physical properties: (1) BET specific surface area is 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 End

2. An epoxy resin curing agent comprising the silica-titania composite oxide according to claim 1, which serves as a filler and also as an epoxy resin curing agent.

3. The cumulative 50% weight diameter (D) calculated from the weight-based particle size distribution obtained by centrifugal sedimentation method ５０ ) and the cumulative 90% weight diameter (D ９０ 3. The epoxy resin curing agent according to claim 1, wherein the following relationship is satisfied: 0.3 ≦ (D ９０ -D ５０ ) / D ５０ ≦0.5

4. 3. A resin composition comprising an epoxy resin and a curing agent for epoxy resins comprising the silica-titania composite oxide according to claim 1 or 2.

5. A semiconductor encapsulant comprising the resin composition according to claim 4.

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