Surface-treated silica powder, resin composition using the same and liquid dispersion

Abstract

To provide silica powder filling a gap between a semiconductor chip and a wiring board with a uniform composition without segregation between the chip and the board in the underfill of a semiconductor device.SOLUTION: The surface-treated silica powder is surface-treated by a silane coupling agent and a titanate coupling agent. In the surface-treated silica powder, the titanate coupling agent is preferably tris(dodecylbenzenesulfonato-κO) (propane-2-olato-κO)titanium or tri-isostearoyl oxyisopropoxy titanium. The surface-treated silica powder is preferably surface-treated with the titanate coupling agent by a ratio of 0.01 to 5.00 pts.mass relative to 100 pts.mass of silica.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a surface-treated silica powder, and a resin composition and dispersion using the same. [Background technology]

[0002] In recent years, as electronic devices have become more powerful and smaller and lighter, the semiconductor packages they are used in have become more highly integrated, denser, and thinner. To commercialize such semiconductor packages, it is essential to not only design integrated circuits but also develop encapsulating materials suited to those designs. For example, epoxy resin is typically used as the underfill material between a semiconductor chip and a wiring board. However, the epoxy resin, semiconductor chip, and wiring board all have different linear expansion coefficients. Therefore, if the connection cannot absorb the stress, cracks may occur at the connection. To prevent cracks from occurring, the underfill material is highly filled with a filler such as silica, which has a relatively low linear expansion coefficient.

[0003] Patent Document 1 proposes a surface-treated silica powder that can provide a resin composition with excellent viscosity characteristics and stability over time by providing a physically adsorbed layer of a silane coupling agent on the powder surface to improve affinity with the epoxy resin used in the underfill agent. It discloses that by chemically bonding a silane coupling agent to the silica particle surface and intentionally allowing a large amount of non-chemically bonded silane coupling agent components to be present on the silica particle surface, the reactive hydroxyl groups on the silica particle surface are physically shielded from the resin, resulting in a resin composition with the surface-treated silica powder added that achieves both excellent viscosity characteristics and stability over time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2023 / 189642 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent semiconductor devices, dissimilar metal bonding—such as Cu-Sn dissimilar metal bonding, which uses Cu on the semiconductor chip side and Sn-based solder on the wiring board side—has become increasingly common for electrical connection and conductivity between the semiconductor chip and the wiring board. Generally, different metals have different electron Fermi levels. When the two metals are bonded, electrons migrate from the metal with the higher Fermi level to the metal with the lower Fermi level. The surface of the metal with the higher Fermi level becomes positively charged, while the surface of the metal with the lower Fermi level becomes negatively charged, creating a potential difference that offsets the Fermi level difference. This creates an electric field in the gap between the semiconductor chip and the wiring board where the underfill agent is injected. The surface of the filler is typically positively or negatively charged, and its movement is influenced by the electric field formed by the dissimilar metal bonding. This can lead to segregation of the filler to either the semiconductor chip or the wiring board, resulting in non-uniformity in the underfill area, such as non-uniformity in the thermal expansion coefficient, and significantly reducing the reliability of semiconductor devices. The underfill agent using the surface-treated silica powder disclosed in Patent Document 1 sometimes causes segregation of the filler in the resin when filled between the semiconductor chip and the wiring board.

[0006] Therefore, an object of the present invention is to provide a silica powder suitable as an underfill filler for semiconductor devices designed to bond and conduct electricity between a semiconductor chip and a wiring board using dissimilar metals. That is, to provide a silica powder that, in the underfill of semiconductor devices, fills the gap between the chip and the board with a uniform composition without segregating between the semiconductor chip and the wiring board. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems and have found that by treating the surface of silica powder with a titanate coupling agent in addition to a silane coupling agent, the silica powder can acquire the property of being unaffected by an electric field. The surface-treated silica powder of the present invention is surface-treated with a silane coupling agent and a titanate coupling agent. In the surface-treated silica powder of the present invention, the titanate coupling agent may be tris(dodecylbenzenesulfonato-κO)(propane-2-olato-κO)titanium or triisostearoyloxy-isopropoxytitanium. The surface-treated silica powder of the present invention is preferably surface-treated with the titanate coupling agent in an amount of 0.01 to 5.00 parts by mass per 100 parts by mass of silica. The surface-treated silica powder of the present invention preferably has a coarse particle content (V90) of 10 or more and less than 100, calculated by formula (1) from the cumulative 50 volume % diameter (D50) and cumulative 90 volume % diameter (D90) of the volume-based particle size distribution obtained by laser diffraction scattering. V90 = {(D90 - D50) / D50 × 100 (1) The surface-treated silica powder of the present invention has a BET specific surface area of ​​1 to 25 m 2 / g is preferred. The resin composition of the present invention is obtained by dispersing the surface-treated silica powder in a resin. The dispersion of the present invention is obtained by dispersing the surface-treated silica powder in a liquid solvent. [Effects of the Invention]

[0008] The surface-treated silica powder of the present invention has silica particles surface-treated with a titanate coupling agent in addition to a silane coupling agent, and therefore has the property of being unaffected by an electric field. Therefore, it can be suitably used as a filler in an underfill agent for semiconductor devices designed to bond a semiconductor chip and a wiring board with dissimilar metals. It is presumed that these characteristics arise because the surface charge of the silica particles approaches neutrality due to the titanate coupling agent, or because steric hindrance increases when the titanate coupling agent, which has bulky substituents, is bonded to the filler. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Surface-treated silica powder) The surface-treated silica powder of the present invention will be described in detail below. The surface-treated silica powder of the present invention is surface-treated with a silane coupling agent and a titanate coupling agent.

[0010] The silane coupling agent may be one represented by the following chemical formula (1). R n -Si-X (4-n) (1) In the above formula (1), R is an organic group having 1 to 18 carbon atoms, X is a hydrolyzable group, and n is an integer of 1 to 3. Examples of X include alkoxy groups having 1 to 3 carbon atoms, such as methoxy, ethoxy, and propoxy, and halogen atoms such as chlorine, with methoxy and ethoxy being preferred. When n is 1 or 2, multiple Xs may be the same or different, but are preferably the same. n is an integer from 1 to 3, preferably 1 or 2, and particularly preferably 1. Examples of the silane coupling agent represented by the formula (1) include methyltrimethoxysilane, methyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxytrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N,N-dimethyl-3-aminopropyltrimethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane, and 4-styryltrimethoxysilane.

[0011] The titanate coupling agent to be surface-treated with the surface-treated silica powder of the present invention includes those represented by the following chemical formula (2). (R) 4-n -Ti-(X) n (2) (In the formula, X is an alkoxy group having 1 to 18 carbon atoms, R is an isostearoyl group, and n is an integer of 1 to 4.) Specific examples include tris(dodecylbenzenesulfonato-κO)(propane-2-olato-κO)titanium and triisostearoyloxy-isopropoxytitanium.

[0012] In addition to the silane coupling agent, at least one surface treatment agent selected from silicone oil, siloxanes, and silazanes may be added. Examples of silicone oils include dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, alkyl-modified silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, carbinol-modified silicone oil, methacrylic-modified silicone oil, polyether-modified silicone oil, and fluorine-modified silicone oil. Examples of siloxanes include disiloxane, hexamethyldisiloxane, hexamethyldicyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and the like, and polysiloxanes such as polydimethylsiloxane. Examples of silazanes include hexamethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, octamethyltrisilazane, hexa(t-butyl)disilazane, hexabutyldisilazane, hexaoctyldisilazane, 1,3-diethyltetramethyldisilazane, 1,3-di-n-octyltetramethyldisilazane, 1,3-diphenyltetramethyldisilazane, 1,3-dimethyltetraphenyldisilazane, 1,3-diethyltetramethyldisilazane, 1,1,3,3-tetraphenyl-1,3-dimethyldisilazane, 1,3-dipropyltetramethyldisilazane, hexamethylcyclotrisilazane, hexaphenyldisilazane, dimethylaminotrimethylsilazane, trisilazane, cyclotrisilazane, and 1,1,3,3,5,5-hexamethylcyclotrisilazane.

[0013] The surface-treated silica powder of the present invention preferably has a one-sided particle size distribution width (V90) of 10 or more and less than 100, calculated by formula (1) from the cumulative 50% volume diameter (D50) and cumulative 90% volume diameter (D90) of the volume-based particle size distribution obtained by laser diffraction scattering. When V90 is within the above range, good gap penetration can be achieved when the resin composition is penetrated into a gap. To further improve gap penetration, V90 is more preferably 10 or more and less than 95, and even more preferably 20 or more and less than 90. V90 = {(D90 - D50) / D50 × 100 (1)

[0014] The surface-treated silica powder of the present invention has a BET specific surface area of ​​1 to 25 m 2 When the BET specific surface area is within the above range, the viscosity of the resin composition can be kept low even if a large amount is filled into the resin. For even lower viscosity, use 1 to 22.5 m 2 / g is more preferable, and 2 to 20m 2 / g is a more preferred embodiment.

[0015] (Method of manufacturing surface-treated silica powder) Next, the method for producing the surface-treated silica powder of the present invention will be described in detail.

[0016] Sol-gel silica can be used as the base silica for surface treatment in the present invention. Sol-gel silica is obtained by hydrolyzing and polymerizing an alkoxysilane such as tetraalkoxysilane in a liquid containing water, a catalyst, an organic solvent, etc. to obtain a spherical silica dispersion, subjecting the resulting dispersion to solid-liquid separation, extracting the silica solids, and then drying and calcining the resulting mixture. A classification step may be added during or after calcination. In addition, flame-processed silica can also be used as the base silica to be surface-treated in the present invention. Flame-processed silica is obtained by burning silicon or a silicon compound to produce silica, which is then separated from the air stream and recovered. A classification step may be performed during or after the process.

[0017] After the silica powder serving as the base material is obtained, a silane coupling agent and a titanate coupling agent are mixed with it by a conventionally known method. For example, silica powder is placed in a mixing container, and the silica powder is fluidized by shaking, stirring, or the like, and then predetermined amounts of silane coupling agent and titanate coupling agent are added by dripping, spraying, or the like. For example, silica powder is added to the container, and stirring is initiated by rotating a stirring blade. The silane coupling agent and titanate coupling agent are then added using a pump or the like. The addition rate can be appropriately changed depending on the amount added. The amount of the silane coupling agent to be used for treatment is preferably 0.10 to 16.00 parts by mass, more preferably 0.20 to 8.00 parts by mass, and even more preferably 0.30 to 5.00 parts by mass, relative to 100 parts by mass of hydrophilic silica. The amount of titanate coupling agent used for treatment is preferably 0.01 to 5.00 parts by mass, more preferably 0.05 to 3.00 parts by mass, and even more preferably 0.1 to 2.50 parts by mass, relative to 100 parts by mass of hydrophilic silica. Silane coupling agents and titanate coupling agents may also be added by mixing them with a solvent. Examples of solvents that can be used include water, alcohols, ethers, ketones, and other organic solvents. Specific examples include methanol, ethanol, 1-propanol, isopropyl alcohol, isobutyl alcohol, cyclohexanol, diethyl ether, dimethyl ether, methyl ethyl ketone, acetone, methyl acetate, ethyl acetate, n-butyl acetate, n-hexane, cyclohexane, tetrahydrofuran, chloroform, benzene, toluene, and xylene.

[0018] Other additives (surface treatment agents) may be added simultaneously with the silane coupling agent, or may be added after the surface treatment agent. Furthermore, the surface treatment agent may be added after the silane coupling agent. This allows for the production of surface-treated silica powders with various surface properties. The treatment amount of the surface treatment agent is preferably 0.05 to 80 parts by mass, more preferably 0.1 to 60 parts by mass, and most preferably 1 to 20 parts by mass, per part by weight of the silica powder in the case of silicone oil. Similarly, the treatment amount of the siloxane is preferably 0.001 to 40 parts by mass, more preferably 0.003 to 30 parts by mass, and most preferably 0.005 to 20 parts by mass, per part by weight of the silica powder. Similarly, the treatment amount of the silazanes is preferably 0.001 to 40 parts by mass, more preferably 0.003 to 30 parts by mass, and even more preferably 0.005 to 20 parts by mass, per part by weight of the silica powder. After adding each coupling agent, it is preferable to continue stirring for 10 minutes or more, which allows each agent to adhere uniformly to the surface of the silica powder. Examples of mixing vessels include a Henschel-type mixer or a Loedige mixer equipped with stirring blades or mixing blades, an air blender that mixes by air current, a V blender that mixes by rotating or shaking the vessel body, a double-cone mixer, and a rocking mixer.

[0019] After the mixing, a heat treatment is performed, causing some of the silane coupling agent and titanate coupling agent attached to the silica powder surface to react with the silica particle surface (i.e., chemically bond), while the remaining coupling agent remains on the silica particle surface without chemically bonding (i.e., physically adsorbed). If the heat treatment temperature is too low, the reaction proceeds slowly, resulting in reduced production efficiency. If the heat treatment temperature is too high, the silane coupling agent and surface treatment agent decompose, or agglomeration occurs due to rapid polymerization. Therefore, although the temperature depends on the surface treatment agent used, it is generally best to perform the heat treatment at 25 to 300°C, preferably 40 to 250°C. The heat treatment time may be appropriately determined depending on the reactivity of the surface treatment agent used, etc. Usually, a sufficient reaction rate can be obtained within 1 hour to 500 hours. In addition, when the heat treatment can be carried out in the mixing vessel used for mixing, the mixed powder may be subjected to the heat treatment directly in the device.

[0020] After the heat treatment, the silica powder is dried. The drying temperature is not particularly limited, but a high temperature is undesirable because the physically adsorbed coupling agent component volatilizes and is removed from the silica powder, while a low temperature is undesirable because by-products cannot be sufficiently removed. Therefore, the drying temperature is preferably 25 to 200°C, more preferably 25 to 180°C, and even more preferably 25 to 150°C. Drying at 25°C or higher allows for sufficient removal of by-products generated when the silane coupling agent reacts with the silica particle surface. The drying apparatus is not particularly limited, and a conventionally known drying apparatus can be used. Furthermore, if drying is possible in the reaction vessel used in the heat treatment, the treated powder may be subjected to drying treatment directly in the apparatus. Furthermore, to accelerate the drying treatment, the drying apparatus may be ventilated with dry gas. The drying time is not particularly limited and may be appropriately selected depending on the drying conditions, such as the drying temperature and pressure, but generally, a surface-treated silica powder from which by-products have been removed can be obtained by setting the drying time to about 1 to 48 hours.

[0021] The type of resin to be blended with the surface-treated silica powder to produce the resin composition of the present invention is not particularly limited, and may be appropriately selected depending on the desired application, and examples of the resin include epoxy resin, acrylic resin, silicone resin, olefin resin, polyimide resin, and polyester resin. The resin composition may be produced by any known method, and may be produced by mixing the surface-treated silica powder with various resins and other components that may be blended as required. When such a dispersion is mixed with a resin, a resin composition can be obtained in which the silica powder is better dispersed in the resin than when dry silica powder is mixed with the resin. A better particle dispersion means that there are fewer aggregated particles in the resin composition. Therefore, the viscosity characteristics and gap penetration properties of the resin composition containing the silica powder of the present invention as a filler can be further improved. The resin composition can be used as a semiconductor encapsulant or semiconductor mounting adhesive, and a resin composition containing surface-treated silica powder can reduce the linear expansion coefficient and is therefore suitable for such applications.

[0022] The surface-treated silica powder of the present invention can be dispersed in a liquid solvent to form a dispersion. The solvent used to disperse the surface-treated silica powder is not particularly limited as long as it is a solvent in which the surface-treated silica powder can be easily dispersed. Examples of such solvents include water and organic solvents such as alcohols, ethers, and ketones. Examples of the alcohols include methanol, ethanol, and 2-propyl alcohol. A mixed solvent of water and one or more of the organic solvents may also be used. To improve the stability and dispersibility of the surface-treated silica powder, various additives may be added, such as dispersants such as surfactants, thickeners, wetting agents, antifoaming agents, or acidic or alkaline pH adjusters. The pH of the dispersion is not limited. Applications of the dispersion include filling semiconductor encapsulants and semiconductor mounting adhesives. Dispersions, i.e., surface-treated silica powders pre-dispersed in a solvent, can be easily dispersed in resins. For example, by mixing the dispersion with resin and then removing the solvent, an underfill agent with well-dispersed filler can be easily prepared. [Example]

[0023] EXAMPLES In the following, examples and comparative examples will be shown to specifically explain the present invention, but the present invention is not limited to these examples.

[0024] [Example 1] Silica powder A shown in Table 1 was added to a mixing vessel as the base silica to be subjected to surface treatment, and stirring was initiated. Then, 0.02 parts by mass of hexamethyldisilazane (SZ-31, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 parts by mass of silica powder A using a peristaltic pump. Stirring was continued and the mixture was mixed for 15 minutes. Then, 0.2 parts by mass of isopropyl alcohol and 0.1 parts by mass of a titanate coupling agent (9SA, manufactured by Ajinomoto Fine-Techno Co., Ltd.), which had been mixed in advance, were added to the mixing vessel in the same manner and mixed. Next, 0.5 parts by mass of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to the mixing vessel in the same manner and mixed. After mixing, the mixture was heated from room temperature to 40°C over 20 minutes while continuing stirring, and then maintained at 40°C for 60 minutes. The mixture was then heated to 100°C over 60 minutes and maintained at 100°C for 180 minutes, completing the reaction process. After the reaction process was completed, the mixture was cooled and dried by circulating nitrogen through the mixing vessel while maintaining the temperature at 30°C, to obtain a surface-treated silica powder. Table 1 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 2 shows the physical properties of the surface-treated silica powder.

[0025] [Example 2] A surface-treated silica powder was obtained in the same manner as in Example 1, except that 0.1 parts by mass of a titanate coupling agent (TTS manufactured by Ajinomoto Fine-Techno Co., Ltd.) was used.

[0026] [Comparative Example 1] Silica powder A was placed in a mixing vessel as the base silica to be surface-treated, and stirring was initiated. Then, 0.02 parts by mass of hexamethyldisilazane (SZ-31) per 100 parts by mass of silica powder A and 0.5 parts by mass of a silane coupling agent (KBM-403) per 100 parts by mass of silica powder A were added using a peristaltic pump. After the addition, stirring was continued and the mixture was mixed for 15 minutes. After mixing, the mixture was heated from room temperature to 40°C over 20 minutes while continuing stirring, and then maintained at 40°C for 60 minutes. The mixture was then heated to 100°C over 60 minutes and maintained at 100°C for 180 minutes, completing the reaction process. After the reaction process was completed, the mixture was cooled, and while maintained at 30°C, nitrogen was circulated through the mixing vessel to dry, yielding a surface-treated silica powder.

[0027] Comparative Example 2 Silica powder A was placed in a mixing vessel as the base silica to be subjected to surface treatment, and stirring was initiated. Then, 2.0 parts by mass of isopropyl alcohol and 1.0 part by mass of titanate coupling agent (9SA), which had been mixed in advance with 100 parts by mass of silica powder A, were added using a peristaltic pump (). After the addition, stirring was continued and mixing was carried out for 15 minutes. After mixing, the mixture was heated from room temperature to 40°C over 20 minutes while continuing stirring, and then maintained at 40°C for 60 minutes. The mixture was then heated to 100°C over 60 minutes and maintained at 100°C for 180 minutes, completing the reaction process. After the reaction process was completed, the mixture was cooled, and while maintaining the temperature at 30°C, nitrogen was circulated through the mixing vessel to dry, yielding a surface-treated silica powder.

[0028] Comparative Example 3 A surface-treated silica powder was prepared in the same manner as in Comparative Example 2, except that 1.1 parts by mass of a titanate coupling agent (TTS) was used.

[0029] [Reference example 1] This was designated as silica powder A.

[0030] The physical properties of the silica powders of the Examples and Comparative Examples were measured or evaluated as follows. (1) BET specific surface area Using a specific surface area measuring device SA-1000 manufactured by Shibata Rikagaku Co., Ltd., the BET specific surface area S (m 2 / g) was measured.

[0031] (2) Volumetric particle size distribution by laser diffraction scattering method Approximately 0.1 g of surface-treated silica powder was weighed using an electronic balance into a 50 mL glass bottle, and approximately 40 mL of ethanol was added. The mixture was dispersed using an ultrasonic homogenizer (BRANSON, Sonifier 250) at 40 W for 10 minutes. The average particle size (nm) and coefficient of variation of the surface-treated silica powder were then measured using a laser diffraction / scattering particle size analyzer (Beckman Coulter, LS 13 320). The average particle size (nm) referred to here refers to the volume-based cumulative 50% diameter. The cumulative 50% volume diameter (D50) and cumulative 90% volume diameter (D90) were calculated from the obtained volume-based particle size distribution. From the obtained D50 and D90, {(D90 - D50) / D50} × 100 (V90) was calculated.

[0032] (3) Carbon content The carbon content of the surface silica powder was measured using a total nitrogen and total carbon analyzer (Sumika Chemical Analysis Center, Sumigraph NC-22F). Furthermore, after cleaning the surface-treated silica powder using the following method, the carbon content of the washed silica powder was measured. The silica sample used for the measurement was 50 to 100 mg. (Cleaning method) 1) The surface-treated silica powder was suspended in ethanol to a concentration of 3% by mass, and the resulting suspension with a total volume of 30 mL was placed in a centrifuge tube (As One Violamo Centrifuge Tube II 50 mL) and dispersed for 10 minutes using a tabletop ultrasonic cleaner (Branson M2800-J, output 110 W, oscillation frequency 40 kHz; an example of an ultrasonic disperser) to obtain Dispersed Slurry 1. 2) The centrifuge tube containing the dispersed slurry 1 was placed in a centrifuge (CN-1050 manufactured by AS ONE) at 5000 rpm for 30 minutes, after which the supernatant liquid that separated into the upper layer was removed, and a sedimentation cake was obtained in the centrifuge tube (solid-liquid separation). 3) Ethanol was added to the centrifuge tube from 2) above so that the total volume became 30 mL, and dispersion was carried out for 10 minutes in the same manner as in 1) above to obtain a dispersion slurry 2. 4) The above steps 2) to 3) were repeated a total of three times, and the cake 1 obtained in the third step 2) was vacuum dried at room temperature for 1 hour (using an AS ONE molded vacuum desiccator MVD-100 and an AS ONE dry vacuum pump) to obtain a washed powder.

[0033] (4) Calculation of CT ratio The CT ratio is the ratio of the amount of each coupling agent chemically bonded to the surface-treated silica powder per unit area, C, to the total amount, T, of silane coupling agent and titanate coupling agent per unit area of ​​the surface-treated silica powder. The carbon amount, C, per unit mass of the surface-treated silica before cleaning i [kg / kg], the amount of carbon per unit mass of surface-treated silica after cleaning, C w [kg / kg], the amount of titanate coupling agent per unit mass of silica, T i [kg / kg], molecular weight M of titanate coupling agent Ti [kg / mol], the number of carbon atoms contained in one molecule of titanate coupling agent, T C [number / functional group], the number of carbon atoms contained in one molecule of the silane coupling agent, S C [pieces / molecule], specific surface area of ​​hydrophilic silica B [nm 2 / kg], atomic weight A of carbon atom C [kg / mol], Avogadro's number N A The calculation was done using [pieces / mol]. The specific calculation formula is as follows: Amount of titanate coupling agent modified per unit area of ​​silica: Q Ti [pcs / nm 2 ] Q Ti =(T i ×N A ) / (M Ti ×B) Carbon content of titanate coupling agent per unit weight of silica C Ti :[kg / kg] C Ti =(Q Ti ×B) / N A ×T C ×A C The total amount of silane coupling agent chemically bonded or physically adsorbed on the silica surface per unit area of ​​silica, T Si [pcs / nm 2 ] T Si ={(C i -C Ti ) / A C} / (S C -2)×N A / (B×10 21 ) Total amount of silane coupling agent chemically bonded to the silica surface per unit area of ​​silica: C Si [pcs / nm 2 ] C Si ={(C w -C Ti ) / A C} / (S C -2)×N A / (B×10 21 ) Total amount of silane coupling agent and titanate coupling agent per unit area of ​​surface-treated silica powder: T [pieces / nm 2 ] T=T Si +Q Ti The amount of each coupling agent chemically bonded to the surface-treated silica powder per unit area: C [pieces / nm 2 ] C=C Si +Q Ti CT ratio CT=C / T

[0034] (5) Electrophoresis of surface-treated silica powder using epoxy resin (particle segregation evaluation) 0.1 g of surface-treated silica powder, 1.4 g of bisphenol F epoxy resin (YDF-8170C, manufactured by Nippon Steel Chemical & Materials Co., Ltd.), and 0.6 g of amine curing agent (KAYAHARD AA, manufactured by Nippon Kayaku Co., Ltd.) were placed in a mortar and mixed with a pestle for 5 minutes. A second glass sheet was placed on top of a glass sheet with copper foil tape attached parallel to it, leaving a 5 mm gap between the tapes. The glass sheet was heated to 130°C and the hand-mixed resin composition was poured into the glass sheet at high temperature. A voltage of 81 V was applied to the copper foil tape for 20 minutes, and the behavior of the silica particles was observed using a digital microscope (VHX-8000, manufactured by Keyence Corporation). The evaluation results for particle segregation were as follows: when silica in the resin was not segregated as observed under a microscope, it was rated "Good"; when silica in the resin was segregated, it was rated "Poor."

[0035] (6) Evaluation of resin properties using surface-treated silica powder (viscosity, thickening index) 30 g of the surface-treated silica powder was added to 26 g of bisphenol F-type epoxy resin (YDF-8170C, manufactured by Nippon Steel Chemical & Material Co., Ltd.) and mixed by hand. The mixed resin composition was premixed using a planetary centrifugal mixer (THINKY Awatori Rentaro AR-500) (mixing: 1000 rpm, 8 minutes; degassing: 2000 rpm, 2 minutes). The premixed resin composition was stored in a thermostatic water bath at 25°C and then mixed using a three-roll mill (IMEX BR-150HCV, roll diameter φ63.5). The mixing conditions were a mixing temperature of 25°C, a roll distance of 20 μm, and eight mixing passes. An amine curing agent (KAYAHARD AA manufactured by Nippon Kayaku Co., Ltd.) was added to the kneaded resin composition so that the silica content was 50% by mass, and the mixture was kneaded using a planetary centrifugal mixer (THINKY Awatori Rentaro AR-500) (kneading: 1000 rpm, 8 minutes, degassing: 2000 rpm, 2 minutes). The resulting resin composition was degassed under reduced pressure for 30 minutes using a vacuum pump (Sato Vacuum TSW-150). The kneaded resin composition was measured for its initial viscosity (η1) and viscosity after one day (η2) at a shear rate of 5 s-1 using a rheometer (HAAKE MARS40 manufactured by Thermo Fisher Scientific). The measurement temperature was 25°C, and the sensor used was C35 / 1 (cone-plate type, diameter 35 mm, angle 1°, material titanium). The resin composition was stored at 25°C. Using the viscosity (η1) at the time of preparation of the resin composition and the viscosity (η2) after one day, the rate of change in viscosity over time was calculated according to the following formula. Thickening index [times] = η2 / η1

[0036] [Table 1]

[0037] [Table 2]

[0038] In Examples 1 and 2, surface-treated silica powder containing a titanate coupling agent was used, so no segregation of silica was observed in the epoxy resin in the presence of an electric field. This is thought to be because the addition of the titanate coupling agent neutralized the surface charge, preventing the particles from being affected by the electric field, thereby suppressing particle movement. In addition, the bulkiness of the titanate coupling agent structure is thought to increase steric hindrance between particles, making them less likely to aggregate.

Claims

1. A surface-treated silica powder characterized by being surface-treated with a silane coupling agent and a titanate coupling agent.

2. 2. The surface-treated silica powder according to claim 1, wherein the titanate coupling agent is tris(dodecylbenzenesulfonato-κO)(propane-2-olato-κO)titanium or triisostearoyloxy-isopropoxytitanium.

3. 2. The surface-treated silica powder according to claim 1, wherein the titanate coupling agent is used for surface treatment in an amount of 0.01 to 5.00 parts by mass per 100 parts by mass of silica.

4. 2. The surface-treated silica powder according to claim 1, wherein the amount of coarse particles (V90) of the surface-treated silica powder calculated by formula (1) from the cumulative 50 volume % diameter (D50) and cumulative 90 volume % diameter (D90) of the volume-based particle size distribution obtained by a laser diffraction scattering method is 10 or more and less than 100. V90={(D90-D50) / D50×100 (1)

5. BET specific surface area is 1 to 25 m ２ 2. The surface-treated silica powder according to claim 1, wherein the surface-treated silica powder has a molecular weight of 1 / g.

6. A resin composition comprising a resin and the surface-treated silica powder according to any one of claims 1 to 5 dispersed therein.

7. A dispersion obtained by dispersing the surface-treated silica powder according to any one of claims 1 to 5 in a liquid solvent.

Images