Silica powder, resin composition, and dispersion

Abstract

The present invention provides a silica powder making it possible to obtain a resin composition resin that, when used as a resin filler for semiconductor sealing members, exhibits exceptional filling characteristics and narrow-gap-permeating performance in terms of being able to be compounded with a filler while yielding a sufficient filling quantity. This silica powder is characterized by having a volumetric cumulative 50% diameter D50 of 0.05-2.00 μm as measured by laser diffraction scattering, and less than 100 ppm of independent particles exceeding 5 μm as detected by dynamic image analysis.

Description

Silica powder, resin composition and dispersion

[0001] The present invention relates to a silica powder, a resin composition and a dispersion that can be suitably used as a filler for semiconductor encapsulants, liquid crystal sealants, films and the like.

[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.

[0003] 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 each have different linear expansion coefficients. Therefore, if the connection cannot absorb stress, cracks may occur at the connection. To prevent cracks, fillers with a relatively low linear expansion coefficient, such as silica, are dispersed in the underfill material. In this case, a high amount of low-expansion filler is required to reduce the linear expansion coefficient of the encapsulant. Furthermore, underfill materials containing added fillers must penetrate the gap without creating voids, i.e., they must have sufficient narrow-gap penetration.

[0004] In order to increase the loading amount of the filler, a hydrophilic dry silica powder has been proposed that has excellent dispersibility, a small dispersed particle diameter, and a narrow particle size distribution during dispersion (Patent Document 1). However, the silica powder described in Patent Document 1 has a small dispersed particle diameter, so that voids do not occur when the silica powder is allowed to penetrate into gaps. However, the silica powder induces a thickening effect on the resin composition, which increases the viscosity of the resin composition filled with the silica powder, and therefore, there remains a problem that a sufficient loading amount cannot be obtained.

[0005] In addition, a method has been proposed in which the surface of highly uniformly sized silica particles is treated with a silane coupling agent to improve affinity with resins (e.g., Patent Document 2). The silica particles described in Patent Document 2 demonstrate that, while conventional silica particles, when surface-treated with an epoxy group-containing silane coupling agent, tend to aggregate on their own when dried, further surface-treating the silica particles with a nitrogen-containing compound can suppress the aggregation of the silica particles alone, thereby suppressing the increase in viscosity when filled into resin. Furthermore, it has been shown that suppressing aggregation eliminates the need for classification. However, although the amount of aggregated particles can be reduced, the amount of coarse particles that do not pass through a 20 μm sieve, defined as the amount of coarse particles, still remains at 0.1% or more. Therefore, when used as a filler for a sealant, voids are generated during penetration into gaps, resulting in molding defects.

[0006] JP 2014-152048 A JP 2019-189509 A

[0007] Therefore, an object of the present invention is to provide a silica powder that is excellent in gap penetration, and more specifically, to provide a silica powder that can be blended with a sufficient amount of filler to obtain a resin composition that has excellent filling properties and excellent narrow gap penetration.

[0008] The present inventors have conducted extensive research to solve the above problems and have found that even silica powders containing large particles (aggregates and individual particles) have a specific particle size distribution in which the large individual particles have been reduced, and that the resulting resin composition has excellent filling properties when kneaded with a resin to fill the silica powder, excellent narrow gap penetration, and good fluidity and handleability in the powder state. In this invention, "individual particles" refers to primary particles.

[0009] That is, the silica powder of the present invention is a silica powder consisting of spherical silica particles, in which a volume-based cumulative 50% diameter D50 of 0.05 to 2.00 μm and a volume-based cumulative 100% diameter D100 of 5 μm or less are measured by laser diffraction scattering in a dispersion prepared by the following dispersion method A, and the amount of particles exceeding 5 μm in diameter is 100 ppm or more and the amount of independent particles is less than 100 ppm in a dispersion prepared by the following dispersion method B, as detected by dynamic image analysis. [Dispersion method A] A method in which a 5% by mass suspension of silica powder in ethanol is dispersed for 5 minutes using an ultrasonic homogenizer with a frequency of 20 kHz. [Dispersion method B] A method in which a 0.1% by mass suspension of silica powder in water is dispersed for 30 minutes using an ultrasonic cleaner with a frequency of 40 kHz.

[0010] In the silica powder of the present invention, the spherical silica particles are surface-treated with a silane coupling agent, and the amount of the silane coupling agent component is 2.0 to 22.0 particles / nm ２ It is preferable that:

[0011] It is also preferable that the ratio (D100 / D50) of the volume-based cumulative 50% diameter D50 (μm) to the volume-based cumulative 100% diameter D100 (μm) as determined by the laser diffraction scattering method is 1 or more and 5 or less, and it is also preferable that the amount of coarse particles (V90) of the spherical silica particles calculated by formula (1) from the volume-based cumulative 50% diameter D50 and the cumulative 90 volume% diameter (D90) obtained by the laser diffraction scattering method is 10 or more and less than 100.

[0012] V90={(D90-D50) / D50}×100 (1)

[0013] The silica powder of the present invention contains a specific amount of particles with a particle size exceeding 5 μm as detected after dispersion by dispersion method B, making it easy to handle. The volume-based cumulative 50% diameter D50 measured after dispersion by dispersion method A is within a specific particle size range, and the volume-based cumulative 100% diameter D100 is less than a specific particle size. Furthermore, the number of individual particles with a particle size exceeding 5 μm as detected after dispersion by dispersion method B is reduced (the number of individual particles is less than a specific amount). Therefore, resin compositions containing this silica powder can achieve both excellent filling properties and narrow gap penetration. Therefore, it is suitable as a filler for semiconductor encapsulants and semiconductor mounting adhesives. It can be particularly suitable as a filler for high-density mounting resins.

[0014] Silica powder contains both independent particles and agglomerated particles. If the resin composition contains a large number of independent particles or agglomerated particles with large particle sizes (hereinafter, these will also be referred to as large particle sizes) after adding the silica powder and kneading, when the resin composition is used as a filler for semiconductor encapsulation or semiconductor mounting adhesive, the penetration of the resin composition into gaps is hindered by the large particles, and the resin composition is likely to have poor narrow gap penetration properties.

[0015] Although the silica powder of the present invention contains a specific amount of particles with a diameter exceeding 5 μm detected after dispersion by dispersion method B, which applies a weak shear, resin compositions using the silica powder of the present invention have excellent narrow gap permeability because the volume-based cumulative 100% diameter D100 measured after dispersion by dispersion method A, which applies a strong shear, is less than the specific diameter, and the number of independent particles with a diameter exceeding 5 μm detected after dispersion by dispersion method B is less than the specific amount. This is presumably because such silica powder of the present invention contains agglomerated particles and independent particles in a state where no shear is applied before being added to and kneaded with a resin, but after being kneaded with a resin and shear is applied, the agglomerated particles are dispersed by strong shear to become particles with smaller diameters in the resin composition. On the other hand, the independent particles with a diameter exceeding 5 μm detected after dispersion by dispersion method B do not change in diameter due to strong shear, but in the silica powder of the present invention, the amount is reduced to less than the specific amount, so it does not affect narrow gap permeability.

[0016] The silica powder of the present invention will be described in detail below based on embodiments.

[0017] [Silica Powder] The silica powder of the present invention comprises spherical silica particles, and a dispersion of the silica powder dispersed by the following dispersion method A has a volume-based cumulative 50% diameter D50 of 0.05 to 2.00 μm and a volume-based cumulative 100% diameter D100 of 5 μm or less, as measured by a laser diffraction scattering method. [Dispersion Method A] A 5% by mass suspension of the silica powder in ethanol is dispersed for 5 minutes using an ultrasonic homogenizer at a frequency of 20 kHz.

[0018] Dispersion Method A applies a strong shear force using a low-frequency ultrasonic homogenizer, so the measurement results obtained by laser diffraction scattering after dispersion using Dispersion Method A represent the state of the silica powder during the kneading process when it is filled into the resin. By measuring the D100 of the silica powder dispersion obtained by Dispersion Method A, no large particles are detected in the particle size distribution, indicating that the particles can be dispersed by applying a large shear force. However, because the detection level using Laser Diffraction Scattering is on the order of a percentage and the detection sensitivity is low, it is not possible to detect or quantify trace amounts of particles exceeding D100 in the silica powder.

[0019] Here, the volume-based cumulative 50% diameter D50 is 0.05 to 2.00 μm. If it is less than 0.05 μm, it induces a thickening effect on the resin composition, increasing the viscosity of the filled resin composition, and therefore tends to make it difficult to obtain a sufficient filling amount. If it exceeds 2.00 μm, when the filled resin composition is allowed to penetrate into gaps, the difference between the narrow gap and the particle size is small, which inhibits penetration and tends to cause voids. If it is 0.05 to 2.00 μm, the viscosity of the resin composition can be kept low even if a large amount of silica powder is filled into the resin.

[0020] The volume-based cumulative 100% diameter D100 of the dispersion obtained by the silica powder dispersion method A, as measured by the laser diffraction scattering method, is 5 μm or less, preferably less than 3 μm.

[0021] Here, if the volume-based cumulative 100% diameter D100 exceeds 5 μm, the particles present will hinder gap penetration, generating voids and causing molding defects. If D100 is 5 μm or less and the amount of independent particles exceeding 5 μm, as measured by the method described below, is less than 100 ppm, good narrow gap penetration can be achieved when the resin composition penetrates gaps, even if a large amount of silica powder is added to the resin. The volume-based cumulative 100% diameter D100 is preferably 3 μm or less.

[0022] Furthermore, the silica powder of the present invention has a dispersion liquid dispersed by the following dispersion method B, in which the amount of particles exceeding 5 μm is 100 ppm or more and the amount of independent particles exceeding 5 μm is less than 100 ppm, as detected by dynamic image analysis: [Dispersion method B] A 0.1 mass % aqueous suspension of silica powder is dispersed in an ultrasonic cleaner at a frequency of 40 kHz for 30 minutes.

[0023] As described above, in addition to using laser diffraction scattering to measure the particle size distribution of dispersions dispersed by dispersion method A, which applies a strong shear, dynamic image analysis was also used to measure the amount of particles larger than 5 μm and the amount of independent particles larger than 5 μm for dispersions dispersed by dispersion method B. Because dispersion method B applies a weak shear using a high-frequency ultrasonic cleaner, the particles larger than 5 μm detected by dynamic image analysis include agglomerated particles that disperse with strong shear to form smaller particles, and independent particles that do not disperse even with strong shear. Independent particles larger than 5 μm are particles that do not disperse even with strong shear. To distinguish and detect the agglomerated particles from the independent particles, images were filtered using a parameter indicating shape. Regarding the "circularity" calculated by dynamic image analysis, particles with a circularity of 0.90 or more were determined to have a high circularity and to be independent spherical particles, while particles with a circularity of less than 0.90 were determined to be amorphous and identified as agglomerated particles that are likely to have been formed by the aggregation of primary particles.

[0024] The amount of particles exceeding 5 μm detected by dynamic image analysis of silica powder is 100 ppm or more. As described above, the particles detected here include both aggregated particles formed by aggregation of primary particles and independent particles. If this amount of particles is 100 ppm or more, the flowability of the silica powder can be improved, and the handling properties when adding the silica powder to a resin can be improved.

[0025] On the other hand, the amount of independent particles exceeding 5 μm is less than 100 ppm. Less than 50 ppm is preferable, and less than 10 ppm is more preferable. If the amount of independent particles exceeding 5 μm is 100 ppm or more, the independent particles present may not penetrate into the gaps, causing voids and resulting in molding defects. If the amount is less than 100 ppm, good narrow gap penetration can be achieved when the resin composition penetrates into gaps, even if a large amount of spherical silica particles is added to the resin.

[0026] That is, when the amount of particles exceeding 5 μm detected by dynamic image analysis of a dispersion dispersed by dispersion method B is 100 ppm or more and the amount of independent particles exceeding 5 μm is less than 100 ppm, the silica powder of the present invention before shearing is present with 100 ppm or more of agglomerated particles exceeding 5 μm and independent particles exceeding 5 μm, and therefore has high fluidity and is easy to handle when adding the silica powder to a resin. After being dispersed in a resin by applying strong shearing, the silica powder has agglomerated particles exceeding 5 μm dispersed by the strong shearing, and the amount of independent particles exceeding 5 μm is less than 100 ppm, and even if a large amount of spherical silica particles is added to the resin, the resin composition exhibits good narrow gap penetration when being penetrated into gaps. Furthermore, when the amount of particles exceeding 3 μm detected by dynamic image analysis of a dispersion dispersed by dispersion method B is 100 ppm or more and the amount of independent particles exceeding 3 μm is less than 100 ppm, the silica powder of the present invention before shearing is present with 100 ppm or more of agglomerated particles exceeding 3 μm and independent particles exceeding 3 μm, and therefore has high fluidity and is easy to handle when adding the silica powder to a resin. After dispersing the silica powder in a resin by applying strong shearing, the agglomerated particles exceeding 3 μm are dispersed by the strong shearing, and the amount of independent particles exceeding 3 μm is less than 100 ppm. This means that when the resin composition is allowed to penetrate into gaps, the time required for gap penetration can be shortened even when a large amount of spherical silica particles is added to the resin, and good narrow gap penetration properties are exhibited.

[0027] Furthermore, the circularity of particles of 5 μm or less, as detected by dynamic image analysis of the silica powder, is preferably 0.90 or more. If the circularity is 0.90 or more, the proportion of spherical particles increases, and the fluidity increases, enabling the development of good narrow gap penetration.

[0028] The aspect ratio of particles of 5 μm or less detected by dynamic image analysis of silica powder is preferably 0.92 or more. If the aspect ratio is 0.92 or more, the proportion of spherical particles increases, resulting in high fluidity and enabling good narrow gap penetration.

[0029] In the present invention, the spherical silica particles may be surface-treated with a silane coupling agent. The amount of the silane coupling agent component is 2.0 to 22.0 particles / nm ２ is preferably 4.0 to 18.0 particles / nm ２ The amount of the silane coupling agent component is more preferably 2.0 to 22.0 particles / nm ２ If the ratio is 2.0 / nm, the reactive hydroxyl groups on the surface of the silica particles can be sufficiently blocked from the resin. ２ When the number of reactive hydroxyl groups on the surface of the silica particles is 22.0 / nm or more, the reactive hydroxyl groups on the surface of the silica particles tend to be blocked from the organic resin, thereby improving the affinity. ２ If the amount is less than this, there is a tendency that the amount of excess silane coupling agent is small and the dispersibility of the silica particles is improved.

[0030] The particle size distribution of silica powder can be expressed as the ratio (D100 / D50) of the cumulative 50 volume % diameter D50 of the volume-based particle size distribution obtained by laser diffraction scattering to the maximum particle diameter D100. (D100 / D50) is preferably 1 or more and 5 or less. If (D100 / D50) is 1 or more and 5 or less, the spherical silica particles tend to be packed in the resin in a manner close to closest packing, and even if a large amount of spherical silica particles is packed, the amount of resin that is not enclosed in the gaps between the particles increases, making it possible to maintain a low viscosity of the resin composition.

[0031] Furthermore, the amount of coarse particles in the silica powder can be expressed by V90, which is calculated by the following formula (1).

[0032] V90={(D90-D50) / D50}×100 (1) D50: cumulative 50 volume % diameter of volume-based particle size distribution obtained by laser diffraction scattering method D90: cumulative 90 volume % diameter of volume-based particle size distribution obtained by laser diffraction scattering method V90 is preferably 10 or more and less than 100, more preferably 10 to 95, and even more preferably 20 to 90. When V90 is 10 or more and less than 100, good gap penetration can be obtained when the resin composition is penetrated into a gap.

[0033] [Uses] The use of the silica powder of the present invention is not particularly limited. For example, it can be used as a filler for semiconductor encapsulation materials or semiconductor mounting adhesives, a filler for die attach films or die attach pastes, or a filler for resin compositions such as insulating films for semiconductor package substrates. In particular, the spherical silica particles obtained by the present invention can be suitably used as a filler for resin compositions for high-density mounting.

[0034] Furthermore, the silica powder of the present invention can also be used as an abrasive grain for a CMP (Chemical Mechanical Polishing) abrasive, an abrasive grain for a grinding stone used for grinding, an external additive for toner, an additive for a liquid crystal sealing material, a dental filler, an inkjet coating agent, etc.

[0035] [Method for Producing Silica Powder] Next, a method for producing silica powder of the present invention will be described.

[0036] The silica-based spherical particles are classified to obtain a silica powder consisting of spherical silica particles, as described in detail below.

[0037] <Silica-Based Spherical Particles> The silica-based spherical particles used in the present invention are preferably silica-based spherical particles having an average particle diameter of 0.05 to 2.00 μm as measured by the laser diffraction scattering method.

[0038] Alternatively, the silica-based spherical particles may be a wet-process silica-based spherical particle dispersion obtained by the sol-gel method, in which a silicon alkoxide is hydrolyzed and polycondensed in a reaction medium consisting of water and an organic solvent containing a catalyst to produce a silica sol, which is then gelled to obtain a wet-process silica-based spherical particle dispersion.

[0039] Alternatively, dry silica-based spherical particles obtained by a flame method may be used as the silica-based spherical particles. Here, the flame method involves burning a silicon compound to produce the dry silica-based spherical particles, which are grown and aggregated in and near the flame to obtain the dry silica-based spherical particles. For example, International Publication No. 2020 / 175160 discloses a method for producing silica by burning a silicon compound, in which a burner having a concentric multi-tube structure of three or more tubes is installed in a reactor with a cooling jacket around it, and the combustion conditions and cooling conditions of the flame are adjusted to obtain a silica powder having a cumulative 50% mass diameter of 300 nm or more and 500 nm or less in the mass-based particle size distribution obtained by centrifugal sedimentation.

[0040] <Classification Treatment> Spherical silica particles with a reduced number of independent particles can be obtained by classifying silica-based spherical particles. For example, the wet silica-based spherical particle dispersion is wet-filtered to remove the contained independent particles. That is, by filtering the wet silica-based spherical particle dispersion, the independent particles, as well as any adhered particles or agglomerates present on the filter material, are also separated along with reaction residues and the like. Here, the filter material can be a wet filtration filter with a mesh size of 5 μm or less, with a mesh size of 3 μm or less being preferred. If the mesh size is too small, not only does the filterability decrease but the average particle size of the filtered silica particles also varies significantly from the above range. Therefore, although the lower limit of the mesh size is usually 1 μm, depending on the average particle size of the target powder, the filter material can be made of any material, including resins (polypropylene, PTFE, etc.) and metals. To prevent the inclusion of metal impurities, a resin filter is preferred.

[0041] Furthermore, since the dry silica-based spherical particles are produced in the form of a powder, they may be dispersed in a solvent and then subjected to wet filtration. The solvent is not particularly limited, but it is preferable to select a solvent in which the dry silica-based particles can be easily dispersed.

[0042] Alternatively, classification using inertial force, such as a liquid cyclone or air classification, may be used. The medium used is not particularly limited, but it is preferable to use a liquid for wet silica-based spherical particles and air for dry silica-based spherical particles, as these particles are more easily dispersible in the medium.

[0043] <Separation Treatment> In this embodiment, the spherical silica particles obtained by classification may be subjected to solid-liquid separation as needed and collected as a cake. Alternatively, a coagulant may be added to form weak aggregates, followed by solid-liquid separation. By adding the coagulant, the solid and liquid can be separated and easily collected. The filtration method is not particularly limited, and known methods such as vacuum filtration, pressure filtration, and centrifugal filtration can be applied.

[0044] Furthermore, the additive to be added is not particularly limited, but from the viewpoint of concerns about contamination of the resulting spherical silica particles, a coagulant consisting of a compound that does not contain metal element components, such as carbon dioxide, ammonium carbonate, ammonium bicarbonate, and ammonium carbamate, is preferred.

[0045] <Drying Treatment> In this embodiment, the cake containing the spherical silica particles obtained by the separation treatment can be dried as needed to obtain silica powder made of spherical silica particles.

[0046] The drying method is not particularly limited, and known methods such as air drying, drying under reduced pressure, etc. However, drying under reduced pressure tends to result in easier crushing than drying under atmospheric pressure, so it is preferable to use drying under reduced pressure.

[0047] The drying temperature is preferably 35 to 200° C., more preferably 50 to 200° C., particularly preferably 80 to 200° C., and particularly preferably 120 to 200° C. A drying temperature of 35 to 200° C. is advantageous from the viewpoint of obtaining silica powder that is easily crushed.

[0048] <Caking Treatment> In this embodiment, the silica powder containing spherical silica particles obtained by the drying treatment can be calcined as needed.

[0049] After drying, silica powder containing spherical silica particles has not completely removed the dispersant absorbed in the particles, leaving silanol groups. In particular, spherical silica particles made using wet-process silica-based spherical particles have pores. To thoroughly remove the dispersant from the particles and crush the silanol groups to obtain solid silica, a further calcination process is preferably performed depending on the application. That is, silica particles treated in the calcination process are preferred not only because the amount of silanol groups on the particle surface is reduced, but also because the dispersant remaining in the particles has been removed. When used as a resin filler, the solvent remaining in the particles generates bubbles upon heating, resulting in a decrease in yield. This is particularly noticeable in applications with high filling rates, such as semiconductor encapsulants and liquid crystal sealants. Therefore, it is preferable to include this process in the production of silica particles, particularly those used for semiconductor encapsulants and liquid crystal sealants.

[0050] If the calcination temperature during the calcination treatment is too low, it becomes difficult to remove the dispersion medium components, and if it is too high, fusion of the silica particles occurs, so it is preferable to carry out the calcination treatment at 300 to 1300°C, and even more preferably 600 to 1200°C. The calcination time is not particularly limited as long as the remaining dispersion medium is removed, but if it is too long, productivity decreases, so it is sufficient to carry out the calcination by heating to the desired calcination temperature and maintaining it for 0.5 to 48 hours, more preferably 2 to 24 hours. The atmosphere during the calcination is also not particularly limited, and the calcination can be carried out under an inert gas such as argon or nitrogen, or in the air.

[0051] The silica powder of the present invention can be crushed by a known crushing means, if necessary, to further reduce agglomerates before use. The crushing method is not particularly limited, and known methods such as a ball mill or a jet mill can be used.

[0052] [Surface Treatment with Silane Coupling Agent] The spherical silica particles may be surface treated with a silane coupling agent, as described in detail below.

[0053] <Silane Coupling Agent> Examples of the silane coupling agent include those represented by the following formula (2).

[0054] Rｎ -Si-X （４－ｎ） (2) In the above formula (2), 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.

[0055] Examples of X include alkoxy groups having 1 to 3 carbon atoms, such as methoxy, ethoxy, and propoxy, and / or halogen atoms such as chlorine, with methoxy and / or 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.

[0056] Examples of the silane coupling agent represented by the formula (2) 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.

[0057] <Surface Treatment Agent (Other Additives)> In addition to the silane coupling agent, at least one surface treatment agent selected from silicone oil, siloxanes, and / or silazanes may be added. The surface treatment agent may be added simultaneously with the silane coupling agent, or the silane coupling agent may be added after the surface treatment agent has been added. Furthermore, the surface treatment agent may be added after the silane coupling agent has been added. This allows spherical silica particles with various surface properties to be obtained. For example, spherical silica particles composed of trimethylsilyl groups and epoxy groups can be easily obtained.

[0058] The amount of the surface treatment agent used 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 spherical silica particles in the case of silicone oil. Similarly, the amount of the siloxane used 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 spherical silica particles. Similarly, the amount of the silazanes used 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.

[0059] <Mixing> The spherical silica particles and the silane coupling agent are mixed by a conventionally known method. For example, the spherical silica particles are placed in a mixing vessel, and the spherical silica particles are fluidized by shaking, stirring, etc., and a predetermined amount of the silane coupling agent is added by dripping, spraying, etc. For example, silica powder is added to the vessel, and stirring is initiated by rotating the stirring blades. The silane coupling agent is then added using a peristaltic pump. The addition rate can be appropriately changed depending on the amount added.

[0060] After the silane coupling agent is added, it is preferable to continue stirring for 10 minutes or more, which allows the silane coupling agent to be uniformly attached to the surfaces of the spherical silica particles.

[0061] Examples of mixing vessels include a Henschel-type mixer or a Loedige mixer equipped with a stirring blade or a mixing blade, 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.

[0062] <Heat Treatment> By performing heat treatment, a portion of the added silane coupling agent reacts with the silica particle surface (i.e., chemically bonds), and the remaining silane coupling agent remains on the silica particle surface without chemically bonding (i.e., physically adsorbed). If the heat treatment temperature is low, the reaction proceeds slowly, resulting in a decrease in production efficiency, while if it is high, it promotes the decomposition of the silane coupling agent and surface treatment agent and the formation of agglomerates due to a rapid polymerization reaction. Therefore, although it depends on the silane coupling agent used, it is generally best to perform the heat treatment at 25 to 300°C, preferably 40 to 250°C.

[0063] The heat treatment time may be determined appropriately depending on the reactivity of the silane coupling agent used, etc. Usually, a sufficient reaction rate can be obtained within 1 hour to 500 hours. If the heat treatment can be performed in the mixing vessel used for mixing, the mixed powder may be subjected to the heat treatment directly in the apparatus.

[0064] <Drying Treatment> The drying temperature is not particularly limited, but a high temperature is undesirable because the silane coupling agent component (physical adsorption) that is not chemically bonded to the spherical silica particles will volatilize and be removed from the spherical silica particles, while a low temperature will not be able to sufficiently remove by-products. 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 can sufficiently remove by-products that are generated when the silane coupling agent reacts with the silica particle surface.

[0065] The drying apparatus is not particularly limited, and any conventionally known drying apparatus can be used. In addition, if drying can be performed in the reaction vessel used in the heat treatment, the treated powder may be subjected to drying treatment directly in the apparatus.

[0066] The pressure inside the drying device is preferably atmospheric pressure or higher. Specifically, it is preferably 1000 hPa or higher. By drying at a pressure higher than atmospheric pressure, unreacted silane coupling agent can be sufficiently removed. If the pressure is 1000 hPa or higher, by-products can be sufficiently removed without volatilizing the physically adsorbed silane coupling agent components.

[0067] 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 a surface-treated silica powder from which by-products have been removed can generally be obtained by setting the drying time to about 1 to 48 hours.

[0068] [Dispersion] The silica powder of the present invention can be dispersed in a solvent to form a dispersion. The solvent used to disperse the silica powder is not particularly limited as long as it is a solvent in which the silica powder can be easily dispersed.

[0069] Examples of such solvents that can be used 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 as the solvent. In order to improve the stability and dispersibility of the 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.

[0070] The dispersion can be used to fill semiconductor encapsulants and semiconductor mounting adhesives. Dispersions, i.e., silica powder pre-dispersed in a solvent, can be easily dispersed in resin. For example, by mixing the dispersion with resin and then removing the solvent, an underfill agent with well-dispersed filler can be easily prepared.

[0071] [Resin Composition] The type of resin to be blended with the silica powder to produce the resin composition of the present invention is not particularly limited. The type of resin may be appropriately selected depending on the desired application, and examples thereof include epoxy resin, acrylic resin, silicone resin, olefin resin, polyimide resin, and / or polyester resin.

[0072] The resin composition may be produced by any known method, and may be produced by mixing silica powder with various resins and other components that are blended as required.

[0073] When the dispersion of the present invention 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 dispersion of the silica powder means that there are fewer aggregated particles in the resin composition. Therefore, both 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.

[0074] The resin composition can be used as a semiconductor encapsulant or a semiconductor mounting adhesive. A resin composition containing silica powder can reduce the linear expansion coefficient and is therefore suitable for such applications.

[0075] [Summary] As can be understood from the above explanation, the silica powder according to the first aspect of the present invention is a silica powder consisting of spherical silica particles, characterized in that a dispersion obtained by the following dispersion method A has a volume-based cumulative 50% diameter D50 of 0.05 to 2.00 μm and a volume-based cumulative 100% diameter D100 of 5 μm or less, as measured by a laser diffraction scattering method, and that a dispersion obtained by the following dispersion method B has an amount of particles exceeding 5 μm of 100 ppm or more and an amount of independent particles exceeding 5 μm of less than 100 ppm, as detected by dynamic image analysis. [Dispersion method A] A method in which a 5% by mass suspension of silica powder in ethanol is dispersed for 5 minutes using an ultrasonic homogenizer with a frequency of 20 kHz. [Dispersion method B] A method in which a 0.1% by mass suspension of silica powder in water is dispersed for 30 minutes using an ultrasonic cleaner with a frequency of 40 kHz.

[0076] Such silica powder can achieve a high filling amount when added to a resin, without inhibiting the penetration of the resin composition into gaps, and can achieve both excellent filling properties and narrow gap penetration.

[0077] The silica powder according to the second aspect of the present invention is the silica powder according to the first aspect described above, wherein the spherical silica particles are surface-treated with a silane coupling agent, and the amount of the silane coupling agent component is 2.0 to 22.0 particles / nm ２ It is characterized in that:

[0078] The silica powder according to a third aspect of the present invention is the silica powder according to the first or second aspect described above, characterized in that the ratio (D100 / D50) of the volume-based cumulative 50% diameter D50 (μm) obtained by a laser diffraction scattering method to the volume-based cumulative 100% diameter D100 (μm) is 1 or more and 5 or less.

[0079] The silica powder according to a fourth aspect of the present invention is the silica powder according to the first or second aspect described above, characterized in that the amount of coarse particles (V90) of the silica powder calculated by formula (1) from the volume-based cumulative 50% diameter D50 and the cumulative 90% volume diameter D90 obtained by a laser diffraction scattering method is 10 or more and less than 100.

[0080] V90={(D90-D50) / D50}×100 (1)

[0081] A resin composition according to a fifth aspect of the present invention is obtained by dispersing the silica powder according to the first or second aspect in a resin.

[0082] A dispersion according to a sixth aspect of the present invention is obtained by dispersing the silica powder according to the first or second aspect described above in a solvent.

[0083] 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.

[0084] The methods for measuring and evaluating the physical properties of the silica powder are as follows.

[0085] (Volume-based particle size distribution by laser diffraction scattering method) Approximately 0.5 g of silica powder was weighed out on an electronic balance into a 50 mL glass bottle, 10 g of ethanol was added, and the mixture was dispersed using an ultrasonic homogenizer (Sonifier 250 manufactured by Branson) at a frequency of 20 kHz for 5 minutes. The volume-based cumulative 50% diameter D50 (μm), volume-based cumulative 100% diameter D100 (μm), and volume-based cumulative 90% volume diameter D90 (μm) of the spherical silica particles were then measured using a laser diffraction scattering particle size distribution analyzer (LS 13 320 manufactured by Beckman Coulter). From the obtained D50 and D90, the amount of coarse particles (V90) of the surface-treated silica powder calculated by formula (1) was calculated.

[0086] V90={(D90-D50) / D50}×100 (1)

[0087] (Dynamic Image Analysis) (Method for measuring circularity, aspect ratio, amount of particles larger than 5 μm, and amount of independent particles larger than 5 μm by dynamic image analysis) (1) For the dynamic image analysis, a dispersion of silica powder in pure water was used. The dispersion was prepared by adding 0.03 g of silica powder and 0.1 mL of 0.1 M sodium hydroxide solution to 30 g of ultrapure water to prepare a 0.1 mass % suspension, and then dispersing the suspension in an ultrasonic cleaner at a frequency of 40 kHz for 30 minutes.

[0088] (2) The dispersion obtained in (1) was measured using a dynamic image analyzer (a Paasche analyzer manufactured by Hosokawa Micron Corporation) to obtain particle images in 0.015 mL of the dispersion. The particle images obtained were then calculated internally to obtain the "circular equivalent diameter d," "circularity," and "aspect ratio."

[0089] (3) When calculating the amount of particles larger than 5 μm and the amount of independent particles larger than 5 μm from the particle image obtained in (2), only particles with a "circular equivalent diameter d>5 μm" were selected, and the number of particles larger than 5 μm was counted. Furthermore, particles larger than 5 μm were identified by "circularity ≧0.9" and "aspect ratio ≧0.92," and the number of independent particles larger than 5 μm was counted. Here, the particle's circular equivalent diameter d [μm] was used to calculate the particle amount W [ppm] of particles larger than 5 μm and independent particles larger than 5 μm, respectively, according to the calculation method in (4) below. When calculating the amount of particles larger than 3 μm and the amount of independent particles larger than 3 μm, the calculation was performed in the same manner, except that only particles with a "circular equivalent diameter d>3 μm" were selected from the particle image obtained in (2).

[0090] (4) The mass w [g] per particle was calculated from the equation (i) using the equivalent circle diameter d [μm] obtained from dynamic image analysis. ρ is the true density of amorphous silica, ρ = 2.2 [g m -３ The value of w = ρ × π / 6 × (d÷10 ６ ) ３ (i)

[0091] This procedure was carried out for each particle detected by dynamic image analysis, and the weight of each particle was calculated. The sum of all the weights was taken as the total weight ws [g], and the particle amount W [ppm] of the spherical silica particles used for measurement was calculated using equation (ii). W = ws / (0.015 x (0.1 / 100) (ii)

[0092] The detection limit in this measurement method was calculated by measuring 0.015 mL of a dispersion obtained by adding a known amount of 10 ppm of standard particles 1 (4206A manufactured by Thermo Fisher Scientific) to the dispersion obtained in (1) above. The amount of independent particles obtained by measuring the dispersion to which the standard particles were added represents the detected amount of the standard particles, and from this result, the detection limit for the amount of particles exceeding 5 μm was determined to be 10 ppm. Similarly, a dispersion to which standard particles 2 (4204A manufactured by Thermo Fisher Scientific) were added was measured, and the detection limit for the amount of particles exceeding 3 μm was determined to be 10 ppm.

[0093] (Method for measuring the amount of silane coupling agent component in silica powder) The amount of silane coupling agent component (number / nm) was determined using the carbon amount of the silica powder (described later), the BET specific surface area of ​​the silica powder (described later), and the number of carbon atoms (unitless) of the silane coupling agent. ２ ) was calculated using the following formula:

[0094] Silane coupling agent component amount (pieces / nm ２ ) = carbon content of spherical silica particles (mass%) / 100 / 12 (atomic weight of carbon) / {number of carbon atoms in silane coupling agent - N} × Avogadro's number (pieces / mol) / BET specific surface area of ​​silica powder (m ２ / g) / 10 １８ (In the formula, the number of carbon atoms of the silane coupling agent is the number of carbon atoms in the molecular formula of the silane coupling agent used. For example, when KBM-403 manufactured by Shin-Etsu Silicones is used, the silane coupling agent has the molecular formula C ９ H ２０ O ５ Since the silane coupling agent contains Si, the number of carbon atoms is 9. N is the number of carbon atoms in the hydrolyzable group X of the silane coupling agent multiplied by 2. For example, if X is a methoxy group, N is 2, and if X is an ethoxy group, N is 4. Avogadro's number is 6.02 x 10 ２３ (pieces / mol).

[0095] (Carbon content) The carbon content (mass%) was measured using a total nitrogen and total carbon analyzer (Sumigraph NC-TR22 manufactured by Sumika Chemical Analysis Center). The silica sample to be measured was 50 to 100 mg.

[0096] (BET specific surface area) Using a specific surface area measuring device (SA-1000 manufactured by Shibata Rikagaku), the BET specific surface area S (m ２ / g) was measured.

[0097] (Evaluation of Gap Penetration of Silica Powder) 36 g of silica powder was added to a mixture of 17 g of bisphenol F-type epoxy resin (YDF-8170C, manufactured by Nippon Steel Chemical & Material Co., Ltd.) and 7 g of an amine curing agent (KARAHARD A-A, manufactured by Nippon Kayaku Co., Ltd.), and the mixture was hand-kneaded. The hand-kneaded resin composition was pre-kneaded using a planetary centrifugal mixer (THINKY Awatori Rentaro AR-500) (kneading: 1000 rpm, 8 minutes, degassing: 2000 rpm, 2 minutes). The pre-kneaded resin composition was stored in a thermostatic water bath at 25°C and then kneaded using a three-roll mill (BR-150HCV, manufactured by Imex Co., Ltd., roll diameter φ63.5). The kneading conditions were a kneading temperature of 25°C, a roll distance of 20 μm, and eight passes of kneading. The obtained resin composition was degassed under reduced pressure for 30 minutes using a vacuum pump (TSW-150 manufactured by Sato Vacuum Co., Ltd.) to obtain a kneaded resin composition. This kneaded resin composition was dropped into the entrance of a gap that had been previously formed by stacking two pieces of glass to create a gap of 30 μm and heating them to 110°C, and a high-temperature penetration test was performed. The presence or absence of flow marks was evaluated by visual inspection of the appearance. If no flow marks were observed, the gap penetration was judged to be good, and if flow marks were observed, the gap penetration was judged to be poor. Here, if the gap penetration is good, the silica powder is considered to have excellent filling properties and viscosity characteristics.

[0098] [Example 1-1] 4.3 parts by mass of methanol, 1.7 parts by mass of isopropanol, and 1.4 parts by mass of aqueous ammonia (25% by mass) were prepared as a reaction medium. The reaction temperature was set to 40°C and the mixture was stirred. Subsequently, a mixture of 0.2 parts by mass of tetraethoxysilane, 0.4 parts by mass of methanol, and 0.1 parts by mass of isopropanol was added to the reaction medium as raw materials to produce silica seed particles. Next, 100 parts by mass of tetramethoxysilane and 28.5 parts by mass of methanol were added to the reaction medium, and simultaneously, 42.8 parts by mass of aqueous ammonia (25% by mass) was added to grow and synthesize sol-gel silica particles. After the end of the supply, stirring was continued for 1 hour to obtain a silica-based spherical particle dispersion with an average particle size of 1.0 μm. The silica-based spherical particle dispersion was subjected to wet filtration using a polypropylene filter with a 3 μm mesh to remove independent particles. Subsequently, 0.9 parts by mass of dry ice was added and the mixture was left to stand for 20 hours. After 20 hours, the sol-gel silica particles had settled, and a cake was obtained after solid-liquid separation using quantitative filter paper (particle size retention: 6 μm). The cake was then dried under reduced pressure at 100°C for 15 hours. It was then calcined in an air atmosphere at 800°C for 10 hours. A jet mill was then used to crush the resulting silica powder, yielding silica powder 1. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0099] [Example 1-2] Silica powder 2 was prepared and measured in the same manner as in Example 1-1, except that the mesh size of the polypropylene filter used in wet filtration was changed from 3 μm to 5 μm. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0100] [Example 1-3] In Example 1-1, the reaction medium was changed to 21.4 parts by mass of methanol, 8.6 parts by mass of isopropanol, and 7.1 parts by mass of aqueous ammonia (25% by mass). Thereafter, the raw materials used to prepare silica seed particles were changed to 0.9 parts by mass of tetraethoxysilane, 2.0 parts by mass of methanol, and 0.6 parts by mass of isopropanol, and silica seed particles were prepared. Thereafter, silica powder 3 was prepared and measured in the same manner as in Example 1-1. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0101] [Example 1-4] In Example 1-1, the reaction medium was changed to 83.3 parts by mass of methanol, 33.3 parts by mass of isopropanol, and 27.8 parts by mass of aqueous ammonia (25% by mass). Thereafter, the raw materials used in preparing silica seed particles were changed to 3.3 parts by mass of tetraethoxysilane, 7.8 parts by mass of methanol, and 2.2 parts by mass of isopropanol, and silica seed particles were prepared. Next, the raw materials used after preparing the silica seed particles were changed to 100 parts by mass of tetramethoxysilane, 27.8 parts by mass of methanol, and 44.4 parts by mass of aqueous ammonia (25% by mass). Thereafter, silica powder 4 was prepared and measured in the same manner as in Example 1-1. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0102] [Example 1-5] In Example 1-1, the reaction medium was changed to 50.0 parts by mass of methanol and 8.3 parts by mass of aqueous ammonia (25% by mass). Then, a mixture of 100 parts by mass of tetramethoxysilane, 10.0 parts by mass of methanol, and 46.7 parts by mass of aqueous ammonia (25% by mass) was added as raw materials to the reaction medium, and sol-gel silica particles were grown and synthesized. Thereafter, silica powder 5 was prepared and measured in the same manner as in Example 1-1. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0103] [Example 1-6] In Example 1-1, the reaction medium was changed to 1.8 parts by mass of methanol, 0.7 parts by mass of isopropanol, and 0.6 parts by mass of aqueous ammonia (25% by mass). Thereafter, the raw materials used to prepare silica seed particles were changed to 0.1 parts by mass of tetraethoxysilane, 0.2 parts by mass of methanol, and 0.1 parts by mass of isopropanol, and silica seed particles were prepared. Thereafter, silica powder 6 was prepared and measured in the same manner as in Example 1-1. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0104] [Example 1-7] Silica powder 7 was prepared and measured in the same manner as in Example 1-6, except that the mesh size of the polypropylene filter used in wet filtration was changed from 3 μm to 5 μm. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0105] [Examples 1-8] Five parts by mass of dry silica-based spherical particles (Silfil NSS-40D, manufactured by Tokuyama Corporation) having an average particle size of 0.38 μm was added to 100 parts by mass of pure water to prepare a dry silica-based spherical particle dispersion. This dry silica-based spherical particle dispersion was subjected to wet filtration using a polypropylene filter with a mesh size of 3 μm to remove independent particles, thereby preparing and measuring silica particles 8. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0106] Example 1-9 Silica powder 9 was prepared and measured in the same manner as in Example 1-8, except that dry silica-based spherical particles having an average particle size of 0.24 μm (Silfil NSS-24D, manufactured by Tokuyama Corporation) were used instead of dry silica-based spherical particles having an average particle size of 0.38 μm (Silfil NSS-40D, manufactured by Tokuyama Corporation). Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0107] [Examples 1-10] Dry silica-based spherical particles (Silfil NSS-40D, manufactured by Tokuyama Corporation) with an average particle size of 0.38 μm were classified using an air classifier to prepare and measure silica powder 10. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0108] [Comparative Example 1-1] Silica powder A was prepared and measured in the same manner as in Example 1-1, except that wet filtration using a polypropylene filter with a mesh size of 3 μm was not performed. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0109] [Comparative Example 1-2] Silica powder B was prepared and measured in the same manner as in Example 1-1, except that the mesh size of the polypropylene filter used in wet filtration was changed from 3 μm to 7 μm. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0110] [Comparative Example 1-3] Silica powder C was prepared and measured in the same manner as in Example 1-1, except that the mesh size of the polypropylene filter used in wet filtration was changed from 3 μm to 10 μm. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0111] Comparative Examples 1-4 Measurement was carried out on commercially available spherical silica powder D. Table 1 shows the properties of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0112] Comparative Examples 1-5 Measurement was carried out on commercially available spherical silica powder E. Table 1 shows the properties of the silica powder, and Table 2 shows the physical properties of the silica powder.

[0113]

[0114]

[0115] Example 2-1 The silica powder 1 prepared in Example 1-1 was placed in a mixing vessel and stirring was initiated. Thereafter, 0.01 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones Co., Ltd.) and 0.5 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones Co., Ltd.) were supplied as surface treatment agents to 100 parts by mass of the silica powder 1 using a peristaltic pump (SJ-1211 II-H manufactured by ATTA). After supply, stirring was continued and mixing was carried out for 15 minutes. After mixing, the temperature was increased from room temperature to 40°C over 20 minutes while continuing stirring, and then maintained at 40°C for 60 minutes. The temperature was then increased to 100°C over 60 minutes and maintained at 100°C for 180 minutes, completing the reaction process. After completion of the reaction process, the mixture was cooled, and while maintained at 30°C, nitrogen was circulated through the vessel to dry, yielding a spherical silica powder surface-treated with a silane coupling agent. The physical properties of the resulting surface-treated silica powder were measured. Table 3 shows the properties of the silica powder and the preparation conditions of the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0116] [Example 2-2] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that silica powder 2 was used instead of silica powder 1. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0117] [Example 2-3] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that no surface treatment agent was used and the silane coupling agent was changed to 0.5 parts by mass of a silane coupling agent (KBM-573 manufactured by Shin-Etsu Silicones) per 100 parts by mass of silica powder 1. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0118] Example 2-4 A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.01 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 0.7 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 3. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0119] [Example 2-5] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.02 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 1.2 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 4. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0120] [Example 2-6] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.08 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 4.0 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 5. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0121] [Example 2-7] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.01 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 0.3 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 6. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0122] [Example 2-8] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.01 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 0.3 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 7. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0123] [Example 2-9] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.03 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 1.5 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 8. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0124] [Example 2-10] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.05 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 2.5 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 9. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0125] Example 2-11 A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.03 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 1.5 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 10. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0126] Example 2-12 A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.01 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 0.2 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 1. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0127] Example 2-13 A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.01 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 1.2 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 1. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0128] Example 2-14 A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that 0.01 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 2.4 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of silica powder 1. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0129] [Comparative Example 2-1] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that silica powder A prepared in Comparative Example 1-1 was used instead of silica powder 1. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0130] [Comparative Example 2-2] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that silica powder B prepared in Comparative Example 1-2 was used instead of granular silica powder 1. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0131] [Comparative Example 2-3] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that silica powder C prepared in Comparative Example 1-3 was used instead of silica powder 1. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0132] [Comparative Example 2-4] A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that commercially available spherical silica powder D of Comparative Example 1-4 was used instead of silica powder 1, and 0.01 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 0.9 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of spherical silica powder D. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0133] Comparative Example 2-5 A surface-treated silica powder was prepared and measured in the same manner as in Example 2-1, except that the commercially available spherical silica powder D of Comparative Example 1-4 was used instead of silica powder 1, and 0.01 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicones) and 0.9 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicones) were used per 100 parts by mass of spherical silica powder D. Table 3 shows the properties of the silica powder and the preparation conditions for the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.

[0134]

[0135]

[0136] The silica powders of Examples 1-1 to 1-9, which were filtered using a filter with a mesh size of 5 μm or less to remove independent particles exceeding 5 μm and reduce the amount of independent particles exceeding 5 μm to less than 100 ppm, and Example 1-10, which was classified using an air classifier to remove independent particles exceeding 5 μm and reduce the amount of independent particles exceeding 5 μm to less than 100 ppm, had good gap permeability.

[0137] On the other hand, the spherical silica powders of Comparative Example 1-1, which was not filtered and had an amount of independent particles exceeding 5 μm of 100 ppm or more, Comparative Examples 1-2 to 1-3, which were filtered through a filter with a mesh size of 5 μm or more and had an amount of independent particles exceeding 5 μm of 100 ppm or more, and Comparative Examples 1-4 to 1-5, which were commercially available products and had an amount of independent particles exceeding 5 μm of 100 ppm or more, exhibited poor gap permeability.

[0138] In the surface-treated silica powders, regardless of the type of treatment agent, the silica powders of Examples 2-1 to 2-14 were subjected to filtration through a filter with a mesh size of 5 μm or less or air classification to remove independent particles exceeding 5 μm, and the amount of independent particles exceeding 5 μm was reduced to less than 100 ppm, and the silica powders had good gap permeability.

[0139] On the other hand, the spherical silica powders of Comparative Example 2-1, which was not filtered and had an amount of independent particles exceeding 5 μm of 100 ppm or more, Comparative Examples 2-2 to 2-3, which were filtered through a filter with a mesh size of 5 μm or more and had an amount of independent particles exceeding 5 μm of 100 ppm or more, and Comparative Examples 2-4 to 2-5, which were commercially available products and had an amount of independent particles exceeding 5 μm of 100 ppm or more, exhibited poor gap permeability.

Claims

1. A silica powder consisting of spherical silica particles, characterized in that a dispersion liquid dispersed by the following dispersion method A has a volume-based cumulative 50% diameter D50 of 0.05 to 2.00 μm and a volume-based cumulative 100% diameter D100 of 5 μm or less as measured by a laser diffraction scattering method, and a dispersion liquid dispersed by the following dispersion method B has an amount of particles exceeding 5 μm of 100 ppm or more and an amount of independent particles exceeding 5 μm of less than 100 ppm as detected by a dynamic image analysis method. [Dispersion method A] A method in which a 5% by mass suspension of silica powder in ethanol is dispersed for 5 minutes using an ultrasonic homogenizer with a frequency of 20 kHz. [Dispersion method B] A method in which a 0.1% by mass suspension of silica powder in water is dispersed for 30 minutes using an ultrasonic cleaner with a frequency of 40 kHz.

2. The spherical silica particles are surface-treated with a silane coupling agent, and the amount of the silane coupling agent is 2.0 to 22.0 particles / nm ２ 2. The silica powder according to claim 1 , 3. A silica powder according to claim 1 or 2, in which the ratio (D100 / D50) of the volume-based cumulative 50% diameter D50 (μm) obtained by a laser diffraction scattering method to the volume-based cumulative 100% diameter D100 (μm) is 1 or more and 5 or less.

4. The silica powder according to claim 1 or 2, wherein the amount of coarse particles (V90) of the silica powder calculated from the volume-based cumulative 50% diameter D50 and the volume-based cumulative 90% diameter D90 obtained by a laser diffraction scattering method using formula (1) is 10 or more and less than 100. V90 = {(D90 - D50) / D50} x 100 (1) 5. A resin composition comprising the silica powder according to claim 1 or 2 dispersed in a resin.

6. A dispersion in which the silica powder according to claim 1 or 2 is dispersed in a solvent.

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