Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/113—Silicon oxides; Hydrates thereof
  • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/113—Silicon oxides; Hydrates thereof
  • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
  • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K9/00—Use of pretreated ingredients
  • C08K9/04—Ingredients treated with organic substances
  • C08K9/06—Ingredients treated with organic substances with silicon-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/28—Compounds of silicon
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
  • C09C3/08—Treatment with low-molecular-weight non-polymer organic compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D17/00—Pigment pastes, e.g. for mixing in paints
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/30—Particle morphology extending in three dimensions
  • C01P2004/32—Spheres
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/51—Particles with a specific particle size distribution
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
  • C08K5/541—Silicon-containing compounds containing oxygen
  • C08K5/5415—Silicon-containing compounds containing oxygen containing at least one Si—O bond
  • C08K5/5419—Silicon-containing compounds containing oxygen containing at least one Si—O bond containing at least one Si—C bond

Definitions

• the present invention relates to silica powder, resin compositions and dispersions that can be suitably used as fillers for semiconductor encapsulants, liquid crystal sealants and films, etc.
• the object of the present invention is therefore to provide a silica powder that has excellent gap penetration. More specifically, it is to provide a silica powder that can obtain a resin composition resin with excellent filling properties that allow the filler to be blended while obtaining a sufficient filling amount, and excellent narrow gap penetration.
• independent particles refer to primary particles.
• 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 ⁇ m and a volume-based cumulative 100% diameter D100 of 5 ⁇ m or less are measured by a laser diffraction scattering method in a dispersion liquid dispersed by the following dispersion method A, and the amount of particles exceeding 5 ⁇ m in diameter is 100 ppm or more and the amount of independent particles is less than 100 ppm in a dispersion liquid dispersed by the following dispersion method B, as detected by a dynamic image analysis method.
• Dispersion Method A A 5% by weight 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 0.1% by mass aqueous suspension of silica powder is dispersed in an ultrasonic cleaner having a frequency of 40 kHz for 30 minutes.
• the spherical silica particles are preferably surface-treated with a silane coupling agent, and the amount of the silane coupling agent is preferably 2.0 to 22.0 particles/ nm2 .
• the ratio (D100/D50) of the volume-based cumulative 50% diameter D50 ( ⁇ m) to the volume-based cumulative 100% diameter D100 ( ⁇ m) obtained 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.
• V90 ⁇ (D90-D50)/D50 ⁇ 100 (1)
• the silica powder of the present invention has good handling properties because it contains a specific amount of particles with a particle size exceeding 5 ⁇ m detected after dispersion by dispersion method B, the volume-based cumulative 50% diameter D50 measured after dispersion by dispersion method A is in a specific particle size range and the volume-based cumulative 100% diameter D100 is less than a specific particle size, and the number of independent particles with a particle size exceeding 5 ⁇ m detected after dispersion by dispersion method B is reduced (the number of independent particles is less than a specific amount), so that a resin composition to which the silica powder is added can achieve both excellent filling properties and narrow gap permeability. Therefore, it is suitable as a filler for semiconductor encapsulation materials and semiconductor mounting adhesives. In particular, it can be used suitably as a filler for resins for high-density mounting.
• Silica powder contains both independent and agglomerated particles, and if the resin composition contains a large number of independent or agglomerated particles (hereinafter also referred to as large particle size particles) with large particle sizes after the silica powder is added and kneaded, 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.
• large particle size particles a large number of independent or agglomerated particles
• the silica powder of the present invention contains a specific amount of particles with a particle size exceeding 5 ⁇ m detected after dispersion by dispersion method B, which applies a weak shear, but the resin composition using the silica powder of the present invention has 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 particle size, and the independent particles with a particle size exceeding 5 ⁇ m detected after dispersion by dispersion method B are less than the specific amount.
• silica powder of the present invention contains aggregated particles and independent particles in a state where no shear is applied before being added to and kneaded with a resin, but in the resin composition after kneading with the resin and shear is applied, the aggregated particles are dispersed by strong shear and become particles with a smaller particle size.
• the independent particles with a particle size exceeding 5 ⁇ m detected after dispersion by dispersion method B do not change in particle size due to strong shear, but in the silica powder of the present invention, the amount is reduced to less than the specific amount, so there is no effect on narrow gap permeability.
• silica powder of the present invention will be described in detail below based on an embodiment.
• the silica powder of the present invention is composed of 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 ⁇ m and a volume-based cumulative 100% diameter D100 of 5 ⁇ m or less, as measured by a laser diffraction scattering method.
• Dispersion Method A A 5% by weight suspension of silica powder in ethanol is dispersed for 5 minutes using an ultrasonic homogenizer with a frequency of 20 kHz.
• dispersion method A applies a strong shear with a low-frequency ultrasonic homogenizer
• the measurement results obtained by laser diffraction scattering method after dispersion using dispersion method A represent the state of the silica powder during the kneading process when filling it into resin.
• D100 of the silica powder dispersion using dispersion method A it is possible to show that no large particles are detected in the particle size distribution, and that the particles can be dispersed by applying a large shear.
• the detection level using laser diffraction scattering method 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.
• the silica powder of the present invention has a dispersion dispersed by the following dispersion method B, and the amount of particles exceeding 5 ⁇ m detected by dynamic image analysis is 100 ppm or more and the amount of independent particles exceeding 5 ⁇ m is less than 100 ppm.
• Dispersion Method B A 0.1% by mass aqueous suspension of silica powder is dispersed in an ultrasonic cleaner having a frequency of 40 kHz for 30 minutes.
• the amount of particles larger than 5 ⁇ m and the amount of independent particles larger than 5 ⁇ m were measured by dynamic image analysis for the dispersion liquid dispersed by dispersion method B. Since dispersion method B applies a weak shear using a high-frequency ultrasonic cleaner, the particles larger than 5 ⁇ m detected by dynamic image analysis include aggregated particles that are dispersed by strong shear to become particles with a smaller particle size, and independent particles that do not disperse even with strong shear. Independent particles larger than 5 ⁇ m are particles that do not disperse even with strong shear.
• the image is filtered using a parameter indicating the shape.
• particles with a circularity of 0.90 or more are determined to have a high circularity and are determined to be independent spherical particles, while particles with a circularity of less than 0.90 are determined to be amorphous and are identified as aggregated particles that are likely to have been formed by the aggregation of primary particles.
• the amount of independent particles exceeding 5 ⁇ m 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 ⁇ m is 100 ppm or more, the independent particles present may not penetrate into the gaps, causing voids and resulting in molding defects. If it is less than 100 ppm, good narrow gap penetration can be achieved when the resin composition is allowed to penetrate into gaps, even if a large amount of spherical silica particles are added to the resin.
• the silica powder of the present invention before shear is applied has 100 ppm or more of agglomerated particles exceeding 5 ⁇ m and independent particles exceeding 5 ⁇ m, so has high fluidity and good handleability when adding the silica powder to a resin, and after being dispersed in a resin by applying strong shear, the silica powder has agglomerated particles exceeding 5 ⁇ m dispersed by the strong shear and has less than 100 ppm of independent particles exceeding 5 ⁇ m, and exhibits good narrow gap penetration when the resin composition is allowed to penetrate into gaps, even when a large amount of spherical silica particles are added to the resin.
• the silica powder of the present invention before shearing has 100 ppm or more of agglomerated particles exceeding 3 ⁇ m and independent particles exceeding 3 ⁇ m, so it has high fluidity and good handleability when adding the silica powder to a resin, and after dispersing in a resin by applying strong shearing, the agglomerated particles exceeding 3 ⁇ m are dispersed by the strong shearing, and the independent particles exceeding 3 ⁇ m are less than 100 ppm, so that when the resin composition is penetrated into gaps, the time required for gap penetration can be shortened even if a large amount of spherical silica particles are added to the resin, and good narrow gap penetration is exhibited.
• the circularity of particles of 5 ⁇ m or less detected by dynamic image analysis of silica powder is 0.90 or more. If the circularity is 0.90 or more, the proportion of spherical particles increases and fluidity increases, making it possible to achieve good narrow gap penetration.
• the aspect ratio of particles of 5 ⁇ m 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 and fluidity increases, resulting in good narrow gap permeability.
• the spherical silica particles may be surface-treated with a silane coupling agent.
• the amount of the silane coupling agent is preferably 2.0 to 22.0 pieces/ nm2 , more preferably 4.0 to 18.0 pieces/ nm2 . If the amount of the silane coupling agent is 2.0 to 22.0 pieces/ nm2 , the reactive hydroxyl groups on the surface of the silica particles can be sufficiently blocked from the resin.
• the amount is 2.0 pieces/nm2 or more , the reactive hydroxyl groups on the surface of the silica particles tend to be blocked from the organic resin and the affinity tends to be improved, and if the amount is 22.0 pieces/ nm2 or less, there is little excess silane coupling agent, and the dispersibility of the silica particles tends to be improved.
• 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 permeability can be obtained when the resin composition is permeated into a gap.
• the silica powder of the present invention can be used as an abrasive grain for CMP (Chemical Mechanical Polishing) abrasives, an abrasive grain for grinding stones used for grinding, etc., an external toner additive, an additive for liquid crystal sealant, a dental filler, or an inkjet coating agent, etc.
• CMP Chemical Mechanical Polishing
• dry silica-based spherical particles obtained by a flame method may be used as the silica-based spherical particles.
• the flame method produces the particles by burning a silicon compound, and the dry silica-based spherical particles are obtained by growing and agglomerating in and near the flame.
• WO 2020/175160 discloses that in a method for producing silica by burning a silicon compound, a burner having a concentric multiple tube structure of three or more tubes is installed in a reactor provided 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 the centrifugal sedimentation method.
• the wet silica-based spherical particle dispersion is filtered by a wet method to remove the independent particles contained therein. That is, by filtering the wet silica-based spherical particle dispersion, if independent particles, further adhered particles, and aggregates are generated on the filter material together with reaction residues, etc., these are also separated.
• the filter material can be a wet filtration filter having an opening of 5 ⁇ m or less, and preferably a filter having an opening of 3 ⁇ m or less.
• the dry silica-based spherical particles are produced in the form of a powder, they may be dispersed in a solvent and then filtered using a wet method. There are no particular limitations on the solvent used, but it is preferable to select a solvent in which the dry silica-based particles can be easily dispersed.
• classification processes utilizing inertial forces such as liquid cyclones or wind classification, may be used.
• medium used it is preferable to use liquid for wet silica-based spherical particles and air for dry silica-based spherical particles, as these have good dispersibility in the medium.
• the spherical silica particles obtained by classification may be collected as cake by solid-liquid separation as necessary.Also, a coagulant may be added to form weak aggregates, and then solid-liquid separation may be performed.By adding a coagulant, solid-liquid separation can be performed, and the particles can be easily collected.
• the filtration method is not particularly limited, and known methods such as vacuum filtration, pressure filtration, and centrifugal filtration can be applied.
• 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 made of a compound that does not contain metal element components, such as carbon dioxide, ammonium carbonate, ammonium bicarbonate, and ammonium carbamate, is preferred.
• the cake containing the spherical silica particles obtained by the separation treatment can be dried as necessary to obtain a silica powder consisting of spherical silica particles.
• the drying method is not particularly limited, and known methods such as air drying and drying under reduced pressure can be used.
• drying under reduced pressure tends to result in easier disintegration than drying under atmospheric pressure, so it is preferable to use drying under reduced pressure.
• the silica powder containing spherical silica particles obtained by the drying treatment can be fired as necessary.
• the silica powder containing spherical silica particles After drying, the silica powder containing spherical silica particles has not completely removed the dispersing medium absorbed in the particles, and silanol groups remain, and pores exist in spherical silica particles made of wet-type silica-based spherical particles in particular.
• the firing temperature during the above firing process is too low, it is difficult to remove the dispersion medium components, and if it is too high, fusion of the silica particles occurs, so it is preferable to perform the firing process at 300 to 1300°C, and even more preferably 600 to 1200°C.
• the firing time There are no particular restrictions on the firing time as long as the remaining dispersion medium is removed, but if the firing time is too long, productivity decreases, so it is sufficient to hold the temperature at the desired firing temperature for 0.5 to 48 hours, more preferably 2 to 24 hours, before firing.
• the atmosphere during firing and the firing can be performed under an inert gas such as argon or nitrogen, or in the air.
• the silica powder of the present invention can be used after being subjected to a crushing treatment using a known crushing means in order to further reduce agglomerates.
• the crushing method is not particularly limited, and known methods such as a ball mill or a jet mill can be used.
• the spherical silica particles may be surface-treated with a silane coupling agent, as described in detail below.
• the silane coupling agent may be one represented by the following formula (2).
• R is an organic group having 1 to 18 carbon atoms
• X is a hydrolyzable group
• n is an integer of 1 to 3.
• silane coupling agent represented by the above formula (2) examples 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-aminopropylmethyldime
• ⁇ Surface treatment agents (other additives)>
• 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 is added.
• the surface treatment agent may be added after the silane coupling agent is 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.
• the spherical silica particles and the silane coupling agent are mixed by a conventional method.
• the spherical silica particles are placed in a mixing vessel, and the spherical silica particles are fluidized by shaking or stirring, and a predetermined amount of the silane coupling agent is added by dropping or spraying.
• silica powder is added to the vessel, and stirring is started by rotating the stirring blade.
• the silane coupling agent is added thereto using a peristaltic pump. The addition speed can be appropriately changed according to the amount added.
• the silane coupling agent After adding the silane coupling agent, it is preferable to continue stirring for at least 10 minutes. By continuing to stir, the silane coupling agent can be attached evenly to the surface of the spherical silica particles.
• mixing vessels include Henschel-type mixers and Loedige mixers equipped with stirring blades and mixing blades, air blenders that use air to mix the air current, V blenders that mix by rotating or rocking the container body, double cone mixers, and rocking mixers.
• ⁇ Heat Treatment> By carrying out the heat treatment, a part 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 temperature for the heat treatment is low, the reaction proceeds slowly, resulting in a decrease in production efficiency, and if the temperature is high, the decomposition of the silane coupling agent or the surface treatment agent or the formation of agglomerates due to rapid polymerization reaction will be promoted. Therefore, although it depends on the silane coupling agent used, it is generally recommended to carry out 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 silane coupling agent used, etc. Usually, a sufficient reaction rate can be obtained within 1 hour to 500 hours.
• 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 vessel.
• the drying temperature is not particularly limited, but if the temperature is high, the silane coupling agent component (physical adsorption) that is not chemically bonded will volatilize and be removed from the spherical silica particles, which is not preferable, and if the temperature is low, the 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. By drying at 25°C or higher, the by-products generated when the silane coupling agent reacts with the silica particle surface can be sufficiently removed.
• the device used for drying is not particularly limited, and a conventionally known drying device can be used.
• the treated powder may be subjected to drying treatment directly in the device.
• drying time there are no particular limitations on the drying time, and it may be selected appropriately 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.
• 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 the silica powder is easily dispersed in the solvent.
• Such solvents include, for example, water and organic solvents such as alcohols, ethers, and ketones.
• organic solvents such as alcohols, ethers, and ketones.
• the alcohols include methanol, ethanol, and 2-propyl alcohol.
• a mixed solvent of water and one or more of the organic solvents may be used as the solvent.
• various additives such as dispersants such as surfactants, thickeners, wetting agents, antifoaming agents, or acidic or alkaline pH adjusters may be added. There are no limitations on the pH of the dispersion.
• Dispersions i.e. silica powder that has already been dispersed in a solvent, can be easily dispersed in resin. For example, by mixing the resin with the dispersion and then removing the solvent, an underfill agent with well-dispersed filler can be easily prepared.
• the resin composition can be produced by any known method, by mixing silica powder with various resins and other components as required.
• a resin composition can be obtained in which the silica powder is better dispersed in the resin than when dry silica powder is mixed into the resin.
• a better dispersion of the silica powder means that there are fewer aggregated particles in the resin composition.
• resin compositions include semiconductor encapsulation and semiconductor mounting adhesives, and resin compositions containing silica powder are suitable for such applications because they can reduce the linear expansion coefficient.
• Dispersion Method A A 5% by weight 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 0.1% by mass aqueous suspension of silica powder is dispersed in an ultrasonic cleaner having a frequency of 40 kHz for 30 minutes.
• Such silica powder can achieve a high filling amount when added to resin, without impeding the penetration of the resin composition into gaps, achieving both excellent filling properties and narrow gap penetration.
• the silica powder according to the second aspect of the present invention is characterized in that, in the silica powder according to the first aspect described above, 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/ nm2 .
• the silica powder according to the third aspect of the present invention is characterized in that in the silica powder according to the first or second aspect described above, the ratio (D100/D50) of the volume-based cumulative 50% diameter D50 ( ⁇ m) obtained by the laser diffraction scattering method to the volume-based cumulative 100% diameter D100 ( ⁇ m) is 1 or more and 5 or less.
• V90 ⁇ (D90-D50)/D50 ⁇ 100 (1)
• the detection limit in this measurement method was calculated by measuring 0.015 mL of a dispersion obtained in (1) above with a known amount of 10 ppm standard particle 1 (4206A manufactured by Thermo Fisher Scientific) added.
• the amount of independent particles obtained by measuring the dispersion to which the standard particles were added represents the amount of detected standard particles, and from this result, the detection limit for the amount of particles exceeding 5 ⁇ m was determined to be 10 ppm.
• a dispersion to which standard particle 2 (4204A manufactured by Thermo Fisher Scientific) was added was measured, and the detection limit for the amount of particles exceeding 3 ⁇ m was determined to be 10 ppm.
• the amount of silane coupling agent component (pcs/ nm2) was calculated 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 of the silane coupling agent (unitless) using the following formula.
• the silane coupling agent has the molecular formula C 9 H 20 O 5 Si, so the number of carbon atoms of the silane coupling agent is 9.
• N is the number of carbon atoms of the hydrolyzable group X of the silane coupling agent ⁇ 2.
• X is a methoxy group
• N is 2
• X is an ethoxy group
• N is 4.
• Avogadro's number is 6.02 ⁇ 10 23 (groups/mol).
• the carbon content was measured using a total nitrogen/total carbon analyzer (Sumigraph NC-TR22 manufactured by Sumika Chemical Analysis Center).
• the silica sample to be measured was 50 to 100 mg.
• BET specific surface area S (m 2 /g) was measured by the nitrogen adsorption BET single point method using a specific surface area measuring device (SA-1000 manufactured by Shibata Rikagaku Co., Ltd.).
• the resin composition after pre-kneading was stored in a thermostatic water bath at 25°C, and then kneaded with a three-roll machine (BR-150HCV manufactured by Imex Co., Ltd., roll diameter ⁇ 63.5).
• the kneading conditions were kneading temperature of 25°C, roll distance of 20 ⁇ m, and kneading number of times 8.
• the obtained resin composition was degassed for 30 minutes under reduced pressure 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 form a gap of 30 ⁇ m 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, it was determined that the gap permeability was good, and if flow marks were observed, it was determined that the gap permeability was poor. Here, if the gap permeability was good, it is considered that the silica powder has excellent filling properties and viscosity characteristics.
• Example 1-1 As the reaction medium, 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, and the reaction temperature was set to 40° C. and stirred. Then, 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 prepare seed particles of silica.
• silica-based spherical particle dispersion 100 parts by mass of tetramethoxysilane and 28.5 parts by mass of methanol were supplied to the reaction medium, and 42.8 parts by mass of aqueous ammonia (25% by mass) was supplied at the same time to grow and synthesize sol-gel silica particles. After the end of supply, stirring was continued for 1 hour to obtain a silica-based spherical particle dispersion with an average particle size of 1.0 ⁇ m. The silica-based spherical particle dispersion was subjected to wet filtration using a polypropylene filter with an opening of 3 ⁇ m to remove independent particles. Then, 0.9 parts by mass of dry ice was added and left for 20 hours.
• Example 1-2 Silica powder 2 was prepared and measured in the same manner as in Example 1-1, except that the opening of the polypropylene filter used in the wet filtration was changed from 3 ⁇ m to 5 ⁇ m. Table 1 shows the properties and preparation conditions of the silica powder, and Table 2 shows the physical properties of the silica powder.
• 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 in producing 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 produced. 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.
• 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 the 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 the silica seed particles were prepared.
• 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
• Table 2 shows the physical properties of the silica powder.
• Example 2-1 Silica powder 1 prepared in Example 1-1 was put into a mixing vessel and stirring was started. Then, 0.01 parts by mass of hexamethyldisilazane (SZ-31 manufactured by Shin-Etsu Silicone Co., Ltd.) and 0.5 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicone Co., Ltd.) were supplied as a surface treatment agent to 100 parts by mass of silica powder 1 using a peristaltic pump (SJ-1211 II-H manufactured by ATTA). After supply, stirring was continued as it was and mixed for 15 minutes. After mixing, the temperature was raised from room temperature to 40°C in 20 minutes while continuing stirring, and then maintained at 40°C for 60 minutes.
• SZ-31 manufactured by Shin-Etsu Silicone Co., Ltd.
• KBM-403 manufactured by Shin-Etsu Silicone Co., Ltd.
• 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 of the surface-treated silica powder, and Table 4 shows the physical properties of the surface-treated silica powder.
• 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 Silicone) per 100 parts by mass of silica powder 1.
• 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.
• 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 Silicone) and 0.7 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicone) were used per 100 parts by mass of silica powder 3.
• Table 3 shows the properties of the silica powder and the preparation conditions of the surface-treated silica powder
• Table 4 shows the physical properties of the surface-treated silica powder.
• 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 Silicone) and 0.3 parts by mass of a silane coupling agent (KBM-403 manufactured by Shin-Etsu Silicone) were used per 100 parts by mass of silica powder 6.
• Table 3 shows the properties of the silica powder and the preparation conditions of the surface-treated silica powder
• Table 4 shows the physical properties of the surface-treated silica powder.
• Example 1-10 which was classified using an air classifier to remove independent particles larger than 5 ⁇ m and reduce the amount of independent particles larger than 5 ⁇ m to less than 100 ppm, had good gap permeability.

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