WO2024096021A1 - Sol de silice à faible facteur de pertes diélectriques rendu hydrophobe, et procédé de fabrication de celui-ci - Google Patents

Sol de silice à faible facteur de pertes diélectriques rendu hydrophobe, et procédé de fabrication de celui-ci Download PDF

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WO2024096021A1
WO2024096021A1 PCT/JP2023/039319 JP2023039319W WO2024096021A1 WO 2024096021 A1 WO2024096021 A1 WO 2024096021A1 JP 2023039319 W JP2023039319 W JP 2023039319W WO 2024096021 A1 WO2024096021 A1 WO 2024096021A1
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silica particles
group
substituent
modified silica
silicon atom
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PCT/JP2023/039319
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English (en)
Japanese (ja)
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豪 中田
和也 江原
由紀 松山
雅敏 杉澤
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日産化学株式会社
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    • 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
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds

Definitions

  • the present invention relates to hydrophobized silica particles with a low dielectric tangent, a dispersion thereof, and a method for producing the same.
  • Nano-order particles are also considered to have various advantages, such as being applicable to transparent polymer materials and having a greater composite effect than micro-order fillers (Patent Document 5, Patent Document 6).
  • Patent Documents 7 and 8 there have been proposals to hydrophobize the surfaces of silica particles to increase dispersibility in hydrophobic solvents and thereby improve the ease of storage, transportation, and mixing with resins.
  • Patent No. 6793282 JP 2004-269636 A Patent No. 6546386 Patent No. 5862886 Patent No. 6813815 Japanese Patent No. 6805538 Japanese Patent No. 6746025
  • nano-order particles have various advantages.
  • existing nano-order particles have a high dielectric tangent, making them difficult to apply to materials for electronic devices and the like that operate in high frequency bands.
  • the particles are either left as is or dispersed in a solvent and then composited with the resin material.
  • inorganic particles generally do not have sufficient dispersion stability, particularly in highly hydrophobic solvents, and sedimentation and separation occur, leaving issues in terms of work efficiency and storage.
  • the present invention was made in consideration of the above circumstances, and aims to provide hydrophobic nano-order particles with a low dielectric tangent, specifically, silica particles with a dielectric tangent of less than 0.01 at 1 GHz and a hydrophobicity of 40% or more, and a dispersion thereof.
  • the present invention provides surface-modified silica particles having a hydrophobicity degree of 40% or more, characterized in that the average primary particle diameter is 5 to 500 nm and the dielectric loss tangent at 1 GHz is less than 0.01;
  • the surface-modified silica particles according to the first aspect, from which a surface modifier has been removed are characterized in that the following items (i) and (ii) are satisfied: (i) The ratio (SH 2 O/SN 2 ) of the specific surface area by water vapor adsorption (S H2O ) to the specific surface area by nitrogen adsorption (S N2 ) is 0.6 or less.
  • the total silanol group ratio represented by the following formula (1) is 5% or less.
  • Total silanol group ratio (%) (Q2 ⁇ 2/4+Q3 ⁇ 1/4+Q4 ⁇ 0/4) Equation (1)
  • Q2, Q3, and Q4 each represent the percentage (%) of the peak area derived from each silicon atom structure relative to the total peak area (100%) derived from the silicon atom structure obtained by 29Si NMR measurement, where Q2 represents the percentage of the peak area derived from a silicon atom structure having two oxygen atoms and two hydroxyl groups bonded thereto, Q3 represents the percentage of the peak area derived from a silicon atom structure having three oxygen atoms and one hydroxyl group bonded thereto, and Q4 represents the percentage of the peak area derived from a silicon atom structure having four oxygen atoms bonded thereto.]
  • the surface-modified silica particles according to the first or second aspect characterized in that the ratio of the total number of carbon atoms per unit surface
  • the surface-modified silica particles according to any one of the fourth to sixth aspects in which the organosilicon compound is a compound having a hydrolyzable group together with a substituent selected from the substituent group a.
  • the surface-modified silica particle according to the fourth or fifth aspect in which the surface modifier is at least two types selected from the compounds represented by the following formulas (a) to (c):
  • the surface-modified silica particles are particles whose surfaces are coated with the at least two types of surface modifiers at a ratio of 0.5 to 20 particles per 1 nm2 of the surface area of the particles, or particles whose surfaces are at least partially bound to the at least two types of surface modifiers.
  • a composite material comprising the surface-modified silica particle according to any one of the first to ninth aspects and an organic resin material or a polysiloxane.
  • the composite material according to the eleventh aspect wherein the organic resin material or polysiloxane is at least one selected from the group consisting of a styrene resin, an epoxy resin, a cyanate resin, a phenol resin, an acrylic resin, a maleimide resin, a urethane resin, a polyimide, a polytetrafluoroethylene, a cycloolefin polymer, an unsaturated polyester, a vinyl triazine, a polyphenylene sulfide, a crosslinkable polyphenylene oxide, and a curable polyphenylene ether;
  • the composite material according to the eleventh or twelfth aspect has an application selected from the group consisting of a semiconductor device material, a copper-clad laminate, a flexible wiring material, a flexible display material, an antenna material, an optical wiring material, and a sensing material.
  • the present invention relates to a method for producing a method for producing a semiconductor device comprising the steps (A) to (C) below:
  • Total silanol group ratio (%) (Q2 ⁇ 2/4+Q3 ⁇ 1/4+Q4 ⁇ 0/4) Equation (1)
  • Q2, Q3, and Q4 each represent the percentage (%) of the peak area derived from each silicon atom structure relative to the total peak area (100%) derived from the silicon atom structure obtained by 29Si NMR measurement, where Q2 represents the percentage of the peak area derived from a silicon atom structure having two oxygen atoms and two hydroxy
  • a method for producing surface-modified silica particles As a fifteenth aspect, the method for producing surface-modified silica particles according to the fourteenth aspect, in which either one or both of the step (B) and the step (C) are carried out under reduced pressure; As a sixteenth aspect, the method for producing surface-modified silica particles according to the fourteenth aspect, in which the silica sol prepared in the step (A) has a water content of 0.1 to 5 mass %; As a seventeenth aspect, the method for producing surface-modified silica particles according to the fourteenth aspect, in which the silica sol prepared in the step (A) is an aqueous silica sol hydrothermally synthesized at 200 to 380° C.
  • step (B) a step of subjecting the silica sol obtained in step (B) to solvent replacement with at least one solvent selected from alcohols, ketones, hydrocarbons, amides, esters, ethers, or amines.
  • the present invention relates to a method for producing a surface-modified silica dispersion, comprising the steps of:
  • the surface-modified silica particles of the present invention are hydrophobic and have the effect of exhibiting low dielectric properties. They can also be well dispersed in organic solvents. Furthermore, the silica particles of the present invention can form composite materials with organic resin materials or polysiloxanes, and are therefore expected to be used in the production of semiconductor device materials, etc.
  • FIG. 1 is a diagram (photograph) showing the appearance of a cured film of the composite material containing the surface-modified silica particles and the maleimide resin obtained in Example 5-1 (FIG. 1(B)), and a cured film of only the maleimide resin (FIG. 1(A)).
  • the surface-modified silica particles of the present invention are silica particles having an average primary particle diameter of 5 to 500 nm, a dielectric dissipation factor of less than 0.01 at 1 GHz, and a hydrophobicity of 40% or more (hereinafter also referred to as hydrophobized silica particles).
  • the surface-modified silica particles according to the present invention preferably satisfy the following items (i) and (II) in the silica particles from which the surface modifier has been removed: "Silica particles from which the surface modifier has been removed” refers to silica particles before surface modification with a surface modifier, i.e., unmodified silica particles (without surface modifying groups).
  • the degree of hydrophobicity referred to in this specification is defined as the concentration (%) expressed in terms of the volume of methanol when silica particles begin to wet when mixed with water and methanol (also known as methanol wettability), and is generally used as an index of the hydrophobicity of the silica surface.
  • the method for measuring the hydrophobicity is, for example, as follows. First, 0.2 g of sample particles (hydrophobized silica particles) is placed in a 200 mL container (beaker, flask, etc.) containing 50 mL of water (ion-exchanged water, etc.).
  • the hydrophobic silica particles according to the present invention have a hydrophobicity of 40% or more, preferably 50% or more.
  • a hydrophobicity of 40% or more when dispersed in a highly hydrophobic solvent, the dispersed state can be stably maintained for a long time, and a re-stirring step before use can be simplified/labor-saving, which is expected to facilitate the preparation of a composite material.
  • the average primary particle diameter of the hydrophobized silica particles according to the present invention can be a specific surface area diameter calculated from the specific surface area (S N2 ) measured by the BET method using nitrogen gas as molecules adsorbed onto the particle surfaces.
  • the hydrophobized silica particles according to the present invention can have an average primary particle size in the range of 5 nm to 500 nm, for example, 5 nm to 250 nm, 5 nm to 200 nm, 5 nm to 120 nm, 5 nm to 100 nm, 20 nm to 500 nm, 20 nm to 100 nm, or 40 nm to 100 nm.
  • the average primary particle size of the hydrophobic silica particles 5 nm to 500 nm the particles can exhibit a low dielectric tangent and can be well dispersed in an organic solvent. Furthermore, when the hydrophobic silica particles are used to mold a composite material, defects can be suppressed and high transparency can be achieved.
  • the ratio (S H2O /S N2 ) of the specific surface area due to water vapor adsorption (S H2O ) to the specific surface area due to nitrogen adsorption (S N2 ) is an indicator of the amount of active sites (surface silanols) present per unit surface area of the particle, and a larger value indicates that more active sites are present on the silica surface.
  • the specific surface area by water vapor adsorption (S H2O ) can be measured by the BET method using water vapor as molecules adsorbed onto the particle surface, and as described above, the specific surface area by nitrogen adsorption (S N2 ) can be measured by the BET method using nitrogen gas as molecules adsorbed onto the particle surface.
  • the hydrophobized silica particles (surface-modified silica particles) according to the present invention can be silica particles from which a surface modifier has been removed, and have the specific surface area ratio (S H2O /S N2 ) of 0.6 or less. By using silica particles having such a S H2O /S N2 ratio, the surface of the silica particles can be modified without increasing the dielectric tangent, and the dispersibility in organic solvents can be improved.
  • the hydrophobized silica particles (surface-modified silica particles) according to the present invention can be silica particles from which a surface modifier has been removed, and the specific surface area (S H2O ) determined by water vapor adsorption can be in the range of, for example, 5 to 500 m 2 /g, 5 to 300 m 2 /g, or 5 to 100 m 3 /g.
  • S H2O Specific surface area by water vapor adsorption
  • the hydrophobized silica particles (surface-modified silica particles) according to the present invention can be silica particles from which the surface modifier has been removed, and have a specific surface area (S N2 ) measured by nitrogen adsorption in the range of, for example, 25 to 550 m 2 /g, or 25 to 300 m 2 /g, or 25 to 250 m 2 /g.
  • S N2 Specific surface area by nitrogen adsorption
  • the silicon atoms in silica include silicon atoms that are not bonded to a hydroxy group and silicon atoms that are bonded to one or two hydroxy groups. That is, silicon atoms in silica have four structures as shown in the following formulas: a silicon atom bonded to two oxygen atoms and two hydroxyl groups (Q2), a silicon atom bonded to three oxygen atoms and one hydroxyl group (Q3), and a silicon atom bonded to four oxygen atoms (Q4). Then, by determining the proportions of Q2, Q3, and Q4 in silicon atoms in the silica, the amount of silanol (Si-OH) groups in the silica can be estimated.
  • the total silanol group ratio refers to the ratio of silanol groups present in all silicon atoms of the Q2 to Q4 structures present in the silica particles.
  • the abundance ratio of silanol groups on silicon atoms having the above Q2 to Q4 structures can be measured, for example, by a 29Si NMR method using a water-dispersed silica sol containing silica particles to be investigated for the abundance ratio, or a 29Si NMR method using a silica particle powder.
  • the spectrum obtained by the 29 Si NMR method is subjected to waveform separation, and the peak observed between ⁇ 80 ppm and ⁇ 105 ppm in chemical shift is identified as being derived from the Q2 structure, the peak observed between ⁇ 90 ppm and ⁇ 115 ppm as being derived from the Q3 structure, and the peak observed between ⁇ 95 ppm and ⁇ 130 ppm as being derived from the Q4 structure.
  • the ratio (%) of the area value of each peak Q2 to Q4 to the total area value (100%) of each peak is the content ratio (mol%) of each structure (Q2 to Q4) in the silica particle to be measured.
  • Total silanol group ratio (%) (Q2 ⁇ 2/4+Q3 ⁇ 1/4+Q4 ⁇ 0/4) Equation (1)
  • Q2, Q3, and Q4 respectively represent the ratio (%) of the peak area attributable to each silicon atom structure to the total peak area (100%) attributable to the silicon atom structure obtained by 29Si NMR measurement, i.e., the content ratio of each structure obtained from the above NMR measurement results.
  • Q2 in the silica particles from which the surface modifier has been removed, in a 29 Si NMR method using a water-dispersed silica sol containing silica particles, Q2 can be 0 to 10, 0 to 5, or 0 to 5, Q3 can be 0 to 20, 0 to 15, 1 to 15, or 5 to 15, and Q4 can be 80 to 100, or 85 to 100.
  • Q2 in the silica particles from which the surface modifier has been removed, in a 29 Si NMR method using a silica particle powder, Q2 can be 0 to 10, 0 to 5, or 0 to 5, Q3 can be 0 to 20, 0 to 15, 1 to 15, or 5 to 15, and Q4 can be 80 to 100, or 85 to 100.
  • the hydrophobized silica particles (surface-modified silica particles) of the present invention have a total silanol group rate of 5% or less in silica particles from which the surface modifier has been removed. If the rate is greater than 5%, the dielectric constant and dielectric tangent will not both be low and the dielectric properties will not be exhibited.
  • the ratio of the total number of carbon atoms per unit surface area is 2 to 40, for example, 2 to 20, 5 to 20, or 5 to 15.
  • the unmodified silica particles constituting the hydrophobized silica particles (surface-modified silica particles) of the present invention are not particularly limited in the method of production, but are preferably heat-treated in water at 200 to 380°C.
  • the heat treatment can be carried out using a pressure-resistant container (autoclave).
  • the hydrophobized silica particles of the present invention have at least a portion of their surface coated with at least two types of surface modifiers, or have at least a portion of each of the at least two types of surface modifiers bonded to at least a portion of their surface.
  • surface modification includes both an embodiment in which the surface of a silica particle is coated with a surface modifier, and an embodiment in which the surface modifier is bonded to the surface of a silica particle, and these embodiments are collectively referred to as "surface-modified silica particles".
  • "at least a part of the surface of the silica particle is coated with a surface modifier” means that the surface modifier (such as an organosilicon compound described later) coats at least a part of the surface of the silica particle, that is, it includes an embodiment in which the surface modifier covers a part of the surface of the silica particle and an embodiment in which the surface modifier covers the entire surface of the silica particle. In this embodiment, it does not matter whether or not the organosilicon compound, which is an example of the surface modifier, is bonded to the surface of the silica particle.
  • the surface modifier such as an organosilicon compound described later
  • the surface modifier (such as an organosilicon compound described below) is bonded to at least a portion of the surface of the silica particle, i.e., it includes an embodiment in which the surface modifier is bonded to a portion of the surface of the silica particle, an embodiment in which the surface modifier is bonded to a portion of the surface of the silica particle and covers at least a portion of the surface, and further an embodiment in which the surface modifier is bonded to the entire surface of the silica particle and covers the entire surface.
  • the surface modifier such as an organosilicon compound described below
  • the surface modifier is an organosilicon compound having at least one substituent selected from the group a consisting of an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, and a substituent having an unsaturated bond (these may also be collectively referred to simply as "substituent").
  • the hydrophobized silica particles according to the present invention are surface-modified by at least two of the above-mentioned surface modifiers, that is, surface-modified by two or more of the organosilicon compounds having at least one substituent selected from the above-mentioned substituent group a.More specifically, for example, surface-modified by at least two of the organosilicon compounds having at least one substituent a1 selected from the above-mentioned substituent group a and having at least one substituent a2 selected from the above-mentioned substituent group a and different from the above-mentioned substituent a1.Note that, when there are multiple substituents selected from the substituent group a in one organosilicon compound, the substituent with the highest three-dimensional bulkiness among these substituents is treated as the substituent a1 or the substituent a2.
  • the substituent a1 and the substituent a2 are preferably groups having different steric bulkiness.
  • the organosilicon compound may be any compound having a substituent selected from the above-mentioned substituent group a, and examples thereof include silicon compounds having the above-mentioned substituent and a hydrolyzable group described below, organosilicon compounds having the above-mentioned substituent and a Si-O-Si bond, and organosilicon compounds having the above-mentioned substituent and a Si-N-Si bond.
  • substituents in the substituent group a include methyl groups, ethyl groups, propyl groups, butyl groups, hexyl groups, octyl groups, nonyl groups, decyl groups, dodecyl groups, hexadecyl groups, phenyl groups, phenylmethyl groups, tolyl groups, xylyl groups, and vinyl groups.
  • substituents in the substituent group a i.e., alkyl groups having 1 to 20 carbon atoms, aryl groups having 6 to 12 carbon atoms, and substituents having an unsaturated bond
  • substituents in the substituent group a include methyl groups, ethyl groups, propyl groups, butyl groups, hexyl groups, octyl groups, nonyl groups, decyl groups, dodecyl groups, hexadecyl groups, phenyl groups, phenylmethyl groups, tolyl groups,
  • the substituent group a can be a group consisting of a methyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, a phenylmethyl group, a tolyl group and a xylyl group, or can be a group consisting of a methyl group, a phenyl group, a phenylmethyl group and a decyl group.
  • organosilicon compounds for example, a combination of an organosilicon compound having a methyl group and an organosilicon compound having a phenyl group, a combination of an organosilicon compound having a methyl group and an organosilicon compound having a decyl group, a combination of an organosilicon compound having a methyl group, an organosilicon compound having a phenyl group and an organosilicon compound having a decyl group, a combination of an organosilicon compound having a methyl group and an organosilicon compound having a phenylmethyl group, a combination of an organosilicon compound having a methyl group and an organosilicon compound having a tolyl group, a combination of an organosilicon compound having a methyl group and an organosilicon compound having a xylyl group, a combination of an organosilicon compound having a methyl group and an organosilicon compound having an organosilicon compound having an organosilicon compound having
  • Alkoxy groups are preferred as the hydrolyzable groups, and when multiple groups are present, they may be the same or different.
  • As the alkoxy group an alkoxy group having 1 to 3 carbon atoms is preferred, and a methoxy group is particularly preferred.
  • the organosilicon compound is a silicon compound having the above-mentioned substituents and hydrolyzable groups
  • the organosilicon compound there are no particular limitations on the number of substituents and the number of hydrolyzable groups, but it is preferable for the organosilicon compound to have 1 to 3 of the above-mentioned substituents and 1 to 3 of the hydrolyzable groups (with the total number of both groups being 4 or less) per silicon atom.
  • organosilicon compound having a substituent and a hydrolyzable group examples include methyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, methyltripoxysilane, dimethyldipropoxysilane, trimethylpropoxysilane, phenyltrimethoxysilane, tolyltrimethoxysilane, xylyltrimethoxysilane, diphenyldimethylsilane, and the like.
  • silane examples include, but are not limited to, phenyltriethoxysilane, diphenyldiethoxysilane, phenyltripropoxysilane, diphenyldipropoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenyldipropoxysilane, vinyltrimethoxysilane, divinyldimethoxysilane, vinyltriethoxysilane, divinyldiethoxysilane, vinyltripropoxysilane, divinyldipropoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltriethoxysilane.
  • the alkyl groups having 1 to 20 carbon atoms, the aryl groups having 6 to 12 carbon atoms, and the substituents having an unsaturated bond are preferably methyl groups, phenyl groups, phenylmethyl groups, and vinyl groups, and when a plurality of groups are present, they may be the same or different from each other.
  • methyl groups are preferred, and a specific example of the organosilicon compound is hexamethyldisiloxane.
  • the alkyl groups having 1 to 20 carbon atoms, the aryl groups having 6 to 12 carbon atoms, and the substituents having an unsaturated bond are preferably methyl groups, phenyl groups, phenylmethyl groups, and vinyl groups, and when a plurality of groups are present, they may be the same or different from each other.
  • methyl groups are preferred, and a specific example of the organosilicon compound is hexamethyldisilazane.
  • organosilicon compound examples include the compounds represented by the following formulas (a) to (c), and at least one of these and another organosilicon compound, or at least two of these, may be selected.
  • the amount of surface treatment (modification) with the organosilicon compound i.e., the amount of organosilicon compound coating or bonding to the particle surface, per 1 nm2 of the surface area of the silica particle can be in the range of, for example, about 0.5 to 40, or alternatively about 0.5 to 20, about 0.5 to 16, about 1 to 20, about 2 to 20, about 5 to 20, or about 10 to 20.
  • the number per 1 nm2 of surface area (amount of surface treatment) referred to here is the number of all organosilicon compounds required for surface modification, i.e., the total amount of at least two types of surface modifiers, and does not intend the amount of surface treatment with each individual surface modifier (organosilicon compound).
  • the dielectric constant and dielectric loss tangent of the hydrophobized silica particles according to the present invention can be measured using a dry powder of the hydrophobized silica particles with a dedicated device, such as a vector network analyzer (product name: FieldFox N6626A, manufactured by KEYSIGHT TECHNOLOGIES).
  • a dedicated device such as a vector network analyzer (product name: FieldFox N6626A, manufactured by KEYSIGHT TECHNOLOGIES).
  • the hydrophobic silica particles preferably have a dielectric loss tangent of less than 0.01, particularly 0.009 or less at a frequency of 1 GHz.
  • the lower limit of the dielectric loss tangent is 0.00001, 0.00005, 0.0001, or 0.0005.
  • the silica dispersion of the present invention is a dispersion in which the hydrophobized silica particles (surface-modified silica particles) are dispersed in at least one organic solvent selected from alcohols, ketones, hydrocarbons, amides, ethers, esters, and amines.
  • the alcohols include, for example, alcohols having 1 to 5 carbon atoms, and specific examples thereof include methanol, ethanol, isopropyl alcohol, and n-butanol.
  • the ketones include, for example, ketones having 1 to 5 carbon atoms, and specific examples thereof include methyl ethyl ketone, methyl isobutyl ketone, ⁇ -butyrolactone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and cyclohexanone.
  • Examples of the hydrocarbons include toluene, xylene, n-pentane, n-hexane, and cyclohexane.
  • Examples of the amides include dimethylacetamide, N,N-dimethylformamide, dimethylacrylamide, acryloylmorpholine, and diethylacrylamide.
  • Examples of the ethers include ethylene glycol monomethyl ether and propylene glycol monomethyl ether.
  • Examples of the esters include ethyl acetate and butyl acetate.
  • Examples of the amines include triethylamine, tributylamine, N,N-dimethylaniline, pyridine, and picoline.
  • the content of the hydrophobized silica particles in the dispersion can be expressed as a silica concentration.
  • the silica concentration can be calculated by weighing the calcination residue obtained after calcining the silica dispersion at 1000° C.
  • the silica concentration in the silica dispersion can be, for example, 1% by mass to 60% by mass, 10% by mass to 60% by mass, or 10% by mass to 40% by mass.
  • the water content of the silica dispersion is preferably 5% by mass or less. By adjusting the water content to such a level, the stability of the dispersion may be improved and a composite material with an organic resin material or polysiloxane may be easily obtained.
  • the composite material according to the present invention is a composite material containing the hydrophobized silica particles (surface-modified silica particles) according to the present invention and an organic resin material or polysiloxane.
  • the organic resin material or polysiloxane can be at least one selected from the group consisting of epoxy resins, phenolic resins, acrylic resins, maleimide resins, polyurethanes, polyimides, polytetrafluoroethylene, cycloolefin polymers, unsaturated polyesters, vinyl triazines, crosslinkable polyphenylene oxides, and curable polyphenylene ethers.
  • the method for producing the composite material is not particularly limited, but for example, the composite material can be obtained by mixing a dispersion of hydrophobized silica particles with an organic resin material or a monomer or polymer solution of polysiloxane to prepare a polymerizable composition, removing excess solvent, and then curing with light or heat.
  • the composite material can be obtained by directly adding a powder of hydrophobized silica particles to an organic resin material or a monomer or polymer solution of polysiloxane to prepare a polymerizable composition, removing excess solvent, and then curing with light or heat.
  • the polymerizable composition can be cured by light or heat by using a polymerization initiator.
  • a polymerization initiator examples include a photoradical polymerization initiator or a photocationic polymerization initiator
  • thermal polymerization initiator include a thermal radical polymerization initiator or a thermal cationic polymerization initiator.
  • the polymerization initiator can be used in an amount of 0.01 parts by mass to 50 parts by mass relative to 100 parts by mass of the polymerizable compound.
  • additives used in conventional polymerizable compositions for example, various additives used in the relevant technical field, such as catalysts and pigments for curing acceleration, radical scavengers (quenchers), leveling agents, viscosity modifiers, antioxidants, ultraviolet absorbers, stabilizers, plasticizers, and surfactants, can also be mixed and used.
  • the composite material of the present invention can be used as a semiconductor device material, copper-clad laminate, insulating film, flexible wiring material, flexible display material, antenna material, optical wiring material, or sensing material by selecting an appropriate organic resin material or polysiloxane depending on the intended use.
  • the method for producing hydrophobized silica particles (surface-modified silica particles), i.e., the method for coating (surface treating) the surfaces of silica particles with the organosilicon compound is not particularly limited.
  • two or more types of surface modifiers can be added to and mixed with an organic solvent dispersion of (unmodified) silica particles, thereby causing hydrolysis and condensation of the organosilicon compound to modify the surface of the silica particles.
  • the amount of the organosilicon compound added can be such that the surface of the silica particle is modified in a range of, for example, 0.5 to 20.0 pieces of the organosilicon compound per 1 nm2 of the surface area of the silica particle. For example, 0.5 to 15.0 pieces, 1.0 to 10.0 pieces, or 3.0 to 10.0 pieces per 1 nm2 of the surface area of the silica particle can be added.
  • the amount of the organosilicon compound added refers to the total amount (number) of the multiple types of organosilicon compounds added, and when two types of organosilicon compounds are added, for example, it refers to the total amount (number) of the two types of organosilicon compounds added.
  • the preferred amount of the organosilicon compound added is 5.0 to 10.0 pieces per 1 nm2 of the surface area of the silica particle.
  • the hydrolysis of the organosilicon compound may be complete or partial, but water is necessary, and it is preferable to add about 1 mole or more of water per mole of hydrolyzable groups, [Si-O-Si] bonds, or [Si-N-Si] bonds of the organosilicon compound.Moisture contained in an organic solvent can also be used.
  • hydrolysis may be performed completely or partially, but water is required, and it is preferable to add about 1 mole or more of water per mole of the hydrolyzable group of the organosilicon compound.Moisture contained in an organic solvent can also be used.
  • a catalyst may be used during hydrolysis and condensation.
  • a chelate compound an organic acid, an inorganic acid, an organic base, or an inorganic base may be used alone or in combination. More specifically, for example, an aqueous solution of hydrochloric acid, an aqueous solution of acetic acid, an aqueous solution of ammonia, etc. may be used.
  • the hydrophobic silica particles (surface-modified silica particles) according to the present invention can be produced by a process including a step of mixing, in an organic solvent, silica particles having an average primary particle size of 5 nm to 500 nm, a ratio (S H2O /S N2 ) of the specific surface area determined by water vapor adsorption (S H2O ) to the specific surface area determined by nitrogen adsorption (S N2 ) of 0.6 or less, and a total silanol group rate of 5% or less, and a surface modifier which is at least two types of organosilicon compounds having an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, and a substituent having an unsaturated bond.
  • the organosilicon compound can be any of those described above.
  • the silica particles to be surface-modified can be preferably those that have been heat-treated in water at 200 to 380° C. using a pressure-resistant vessel (autoclave) or the like, as described above.
  • the amount of the organosilicon compound added can be an amount that allows the silica particles to be surface-modified at a ratio of, for example, 0.5 to 20 particles per 1 nm2 of surface area.
  • the organosilicon compound can be added so that the silica particles are 0.5 to 15.0 particles, 1.0 to 10.0 particles, 3.0 to 10.0 particles, or 5.0 to 10.0 particles per 1 nm2 of surface area.
  • the amount of the organosilicon compound added is the total amount of two or more organosilicon compounds added, and when three types of organosilicon compounds are added, it is regarded as the total amount of the three types.
  • excess organosilicon compounds that do not contribute to surface modification may be present in the reaction system.
  • the organic solvent used in the mixing step may be an organic solvent containing an alcohol and/or a ketone solvent.
  • the alcohol may be one having 1 to 5 carbon atoms, and specific examples thereof include methanol, ethanol, isopropyl alcohol, and n-butanol.
  • the ketone solvent may be one having 1 to 5 carbon atoms, and specific examples thereof include methyl ethyl ketone, methyl isobutyl ketone, and ⁇ -butyrolactone.
  • the mixing step can be carried out at any temperature, for example, 20° C. or higher and lower than 120° C., as long as the temperature is such that the hydrolysis and condensation reaction of the organosilicon compound proceeds. From the viewpoint of reaction efficiency, it is preferable to carry out the reaction at a temperature near the boiling point of the organic solvent, and for example, when the mixing step is carried out using an organic solvent containing methanol, it is preferable to carry out the reaction at a temperature near 65° C. In addition, in order to suppress changes in the silica concentration and the organosilicon compound concentration during the mixing step, the reaction may be carried out in an apparatus equipped with a reflux device, etc., as necessary.
  • the mixing step may be carried out multiple times at the same temperature, or may be carried out multiple times at different temperatures.
  • the mixing step can be carried out for 30 minutes to 24 hours, and from an industrial viewpoint, it is desirable to carry out the mixing step within 24 hours.
  • surface modification is carried out using at least two kinds of organosilicon compounds (surface modifiers), which may be added at once or separately.
  • at least two kinds of organosilicon compounds may be added separately, for example, the organosilicon compound having the bulkier substituent may be added in order to carry out mixing (reaction).
  • dimethoxyphenylmethylsilane (a)) and hexamethyldisiloxane (a compound represented by the formula (c)) are used as two kinds of organosilicon compounds, dimethoxyphenylmethylsilane having a phenyl group, which is a bulkier substituent, may be added first and mixed, and hexamethyldisiloxane having a methyl group, which is less bulky than the phenyl group, may be added later, but is not limited thereto.
  • the mixing step may include a step of adjusting the pH using an organic amine.
  • This pH adjustment step may be carried out once or multiple times before, during, or after the mixing step.
  • the organic amine may be a secondary or tertiary amine, such as an alkylamine, an allylamine, an aralkylamine, an alicyclic amine, an alkanolamine, or a cyclic amine.
  • the organic base compounds include ethylbenzylamine, piperidine, N-methylpiperidine, quinuclidine, diethanolamine, triethanolamine, N-methyldiethanolamine, N,N-dimethylethanol
  • organic base compounds may be used alone or in combination of two or more.
  • the amount of the organic amine added can be, for example, 0.001 to 5% by mass, or 0.01 to 1% by mass, based on the mass of the silica particles.
  • the pH of the mixed solution can be adjusted to 4.0 to 11.0, for example, pH 7.0 to 10.0, or for example, pH 8.0 to 10.0, by adding the organic amine.
  • the liquid obtained after the mixing step i.e., the liquid containing the surface-modified silica particles
  • the liquid obtained after the mixing step can be used as a surface-modified silica dispersion in the production of the above-mentioned composite material.
  • at least a part of the organic solvent contained in the mixed liquid obtained by the mixing step can be replaced with another organic solvent.
  • the other organic solvent at least one or more selected from the group consisting of alcohols, ketones, ethers, esters, hydrocarbons, and nitrogen-containing organic compounds can be used.
  • organic solvent examples include alcohols such as methanol, ethanol, isopropyl alcohol, and n-butanol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, ⁇ -butyrolactone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and cyclohexanone; ethers such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, and propylene glycol methyl ether acetate; esters such as ethyl acetate and butyl acetate; hydrocarbons such as toluene, xylene, n-pentane, n-hexane, and cyclo
  • a specific example of the method for producing silica particles includes a production method including the following steps (A) to (C), but is not limited to these methods (steps).
  • Total silanol group ratio (%) (Q2 ⁇ 2/4+Q3 ⁇ 1/4+Q4 ⁇ 0/4) Equation (1)
  • Q2, Q3, and Q4 each represent the percentage (%) of the peak area derived from each silicon atom structure relative to the total peak area (100%) derived from the silicon atom structure obtained by 29Si NMR measurement, where Q2 represents the percentage of the peak area derived from a silicon atom structure having two oxygen atoms and two hydroxyl
  • the amount of organosilicon compound added in this production method and the conditions for step (B), i.e., hydrolysis, can be as described above.
  • the silica sol prepared in the step (A) may have a water content of 0.1 to 5% by mass, for example, 3.0% by mass or less.
  • the silica sol prepared in step (A) may be an aqueous silica sol obtained by hydrothermal synthesis at 200 to 380° C. and 2 to 22 MPa, and then solvent-substitution with an alcohol having 1 to 4 carbon atoms.
  • steps (B) and (C) can be carried out, for example, under reduced pressure.
  • a step of adjusting the pH using the above-mentioned organic amine may be included, as necessary, at any one or more of the steps before, during, and after the step (B).
  • step (B) above when at least two types of surface modifiers and the silica sol obtained in the step (A) are heated and stirred, multiple types of surface modifiers may be heated and stirred simultaneously with the silica sol, or some types of the multiple types and the remaining types may be heated and stirred separately with the silica sol, or each type may be heated and stirred individually with the silica sol.
  • the surface modifiers may be heated and stirred with the silica sol in the order starting with the organosilicon compound having the bulkier substituent.
  • the silica sol obtained after the step (B) can be used as a surface-modified silica dispersion in the production of the above-mentioned composite material, and may be subjected to solvent replacement, for example, by the step (D) described below.
  • specific examples of the method for producing a surface-modified silica dispersion include a production method including the following steps (A) and (B), and a production method including step (D) in addition to steps (A) and (B), but are not limited to these methods (steps).
  • silica sol and surface modifiers used in the examples and comparative examples are as follows.
  • the properties of the silica particles are shown in Table 1.
  • [Silica sol] Water-dispersed silica sol a (Nissan Chemical Industries, Ltd., product name: ST-OL, 45 nm, pH 3, silica concentration 20% by mass)
  • Water-dispersed silica sol b (Nissan Chemical Industries, Ltd., product name: ST-O, 12 nm, pH 3, silica concentration 20% by mass)
  • Water-dispersed silica sol c Synthesis Example 1, 80 nm, pH 3, silica concentration 20% by mass)
  • DMMPS dimethoxymethylphenylsilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: LS-2720)
  • DTMS decyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBM-3103C)
  • HMDS hexamethyldisiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KF-96L-0.65CS)
  • silica concentration of the water-dispersed silica sol, the methanol-dispersed silica sol, and the dispersion of surface-modified silica particles was calculated by placing the silica sol or the dispersion in a crucible, heating to remove the solvent, calcining at 1000°C, and weighing the calcination residue.
  • Organic solvent content The content of the organic solvent in the dispersion of the surface-modified silica particles was determined by gas chromatography (Shimadzu Corporation, GC-2014s). Gas chromatography conditions: Column: 3 mm x 1 m glass column Packing material: Polapack Q Column temperature: 130 to 230°C (heating rate: 8°C/min) Carrier: N2 40mL/min Detector: FID Injection volume: 1 ⁇ L The internal standard was acetonitrile.
  • the nitrogen adsorption specific surface area (S N2 ) of the silica particles in the water-dispersed silica sol was measured by removing the water-soluble cations in the water-dispersed silica sol with a cation exchange resin (manufactured by The Dow Chemical Company, product name: Amberlite IR-120B), drying the silica sol at 290°C to prepare a measurement sample, and using a nitrogen adsorption specific surface area measuring device, Monosorb (manufactured by Quantachrome Instruments Japan, LLC), to measure the specific surface area.
  • a cation exchange resin manufactured by The Dow Chemical Company, product name: Amberlite IR-120B
  • NMR Measurement of Silica Sol or Dry Powder of Silica Sol and Calculation of Total Silanol Group Ratio ⁇ NMR Measurement Condition A: 29Si NMR Spectrum Measurement of Silica Sol> 0.5 mL D 2 O was added to 2 mL of water-dispersed silica sol to prepare a measurement sample, which was then placed in a 10 mm diameter polytetrafluoroethylene (PTFE) sample tube for measurement.
  • PTFE polytetrafluoroethylene
  • the measurement conditions were 29 Si resonance frequency of 99.36 MHz, spectrum width of 37.4 kHz, X_Pulse of 90°, Relaxation_Delay of 120 seconds, and measurement temperature of room temperature.
  • Data analysis was performed using JEOL Ltd. software "Delta 5.3.1", and waveform separation analysis was performed on each peak of the spectrum after Fourier transformation, with the center position, height, and half-width of the peak shape created by a Gaussian waveform (Gauss Model) as variable parameters.
  • Gaussian waveform Gaussian waveform
  • ⁇ NMR Measurement Condition B 29Si NMR Spectrum Measurement of Dry Powder of Silica Sol> The silica sol was dried in a vacuum dryer at 100° C. to obtain a measurement sample.
  • a 500 MHz nuclear magnetic resonance apparatus (model name "AVANCE III 500", manufactured by Bruker) was used, a CP/MAS probe with a diameter of 4.0 mm was attached, the observation nucleus was 29Si, and the measurement was performed by the DD/MAS method.
  • the measurement conditions were 29Si resonance frequency of 99.36 MHz, 29Si 90° pulse width of 4.6 ⁇ sec, 1H resonance frequency of 500.13 MHz, MAS rotation speed of 10 kHz, spectrum width of 30 kHz, and measurement temperature of room temperature.
  • Total number of carbon atoms per unit surface area (unit: nm 2 ) of silica particles was calculated by the following procedure. (1) 4 mL of an organic solvent dispersion silica sol of surface-modified silica particles was placed in a 30 cc centrifuge tube, and 20 mL of hexane was added to cause clouding due to aggregation, separation, or precipitation. (2) After centrifuging, the supernatant in which the unbound surface modifier was dissolved was removed.
  • the dynamic light scattering particle size was measured using a dynamic light scattering particle size measuring device (manufactured by Malvern Panalytical, product name: Zetasizer Nano).
  • 0.1 g of the silica particle dispersion was dispensed into a glass cell with an optical path length of 10 mm, and the same solvent as the dispersion medium of the silica particle dispersion was further added to obtain a silica particle dispersion in which the silica concentration was adjusted so that the count rate when the attenuator was 7 was 200 to 400 kcps.
  • the prepared silica particle dispersion was adjusted in the cell so that the height of the liquid surface from the bottom of the cell was about 1 cm, and the dynamic light scattering particle size of the silica particle dispersion was measured with the attenuator 7.
  • Non-Patent Document 1 A. Murota, N. Tsubokawa, Effect of alkyl chain length on the reactivity of ultrafine silica particles with alkylalkoxysilanes in a dry system, Journal of the Japan Society of Colour Material 74 (4), 178-184, 2001.
  • aqueous sodium silicate solution (a) was passed through a column packed with a hydrogen-type strongly acidic cation exchange resin (manufactured by The Dow Chemical Company, trade name: Amberlite IR-120B) at a space velocity of 4.5 per hour to remove cations, thereby preparing an aqueous activated silicic acid solution.
  • the obtained active silicic acid aqueous solution was adjusted to pH 8.5 to 9.5 by adding 10% by mass of sodium hydroxide aqueous solution to obtain a stabilized active silicic acid aqueous solution.
  • the SiO2 concentration of the obtained stabilized active silicic acid aqueous solution was 3.2% by mass.
  • the obtained colloidal silica dispersion was concentrated to a SiO2 concentration of 33 mass% at room temperature using a commercially available ultrafiltration device equipped with a polysulfone ultrafiltration membrane with a molecular weight cutoff of 200,000 (manufactured by Advantec Co., Ltd., product name: Q2000 150E), thereby obtaining a colloidal silica dispersion as a precursor with an adjusted SiO2 concentration.
  • colloidal silica dispersion as a precursor with the adjusted SiO2 concentration was passed through a column packed with a cation exchange resin (manufactured by The Dow Chemical Company, product name: Amberlite IR-120B) at a space velocity of 10 per hour to remove cations, and a 10% by mass aqueous solution of sodium hydroxide was added to the obtained dispersion to adjust the pH to 7 to 8.
  • the colloidal silica dispersion as a precursor with the SiO2 concentration and pH adjusted obtained above was placed in a reaction apparatus equipped with a stirrer, a heater, etc., in a 3 L SUS pressure-resistant container, and the liquid temperature in the container was adjusted to 250 to 260° C. by heating.
  • the container was heated for 9 hours and 20 minutes while maintaining the temperature in the container at 250 to 260° C.
  • 50 g of the colloidal silica dispersion obtained above was placed in a 100 ml plastic container, 25 ml of a cation exchange resin (manufactured by Dow Chemical Company, product name: Amberlite IR-120B) was added, and the mixture was held for 30 minutes while stirring with a magnetic stirrer to remove cations.
  • a cation exchange resin manufactured by Dow Chemical Company, product name: Amberlite IR-120B
  • MEK methyl ethyl ketone
  • DMMPS methyl ethyl ketone
  • diisopropylamine was added so that the pH (1+1+1) was 8.0 to 10.0, and the mixture was heated to 60°C and held for 1 hour to prepare a methanol/MEK dispersion of surface-modified silica particles.
  • the obtained methyl ethyl ketone dispersion of the surface-modified silica particles had a silica concentration of 42.7% by mass, a water content of 0.1% by mass or less, a methanol content of 0.1% by mass or less, a total silanol ratio of 1.7% (Q2: 0%, Q3: 7.0%, Q4: 93.0%, calculated from the 29Si NMR spectrum measured using the procedure shown in the above-mentioned NMR measurement condition B, except that the above methyl ethyl ketone dispersion was dried in a vacuum dryer at 100 °C to prepare a measurement sample), and the ratio of the total number of carbon atoms per unit surface area (unit: nm2 ) of the surface-modified silica particles was 10.
  • Example 1-2 Instead of DMMPS in step (b) of Example 1-1, DTMS was added so that the amount of DTMS was 1.0 particle per nm2 of the surface area of the silica particles contained in the silica sol, and the mixture was similarly maintained at 60° C. for 3 hours. Except for this, operations were carried out in the same manner as in steps (a) to (c) of Example 1-1 to prepare a methanol-dispersed silica sol, a methanol/MEK dispersion of surface-modified silica particles, and a methyl ethyl ketone dispersion of surface-modified silica particles.
  • Examples 1-3 A methanol-dispersed silica sol, a methanol/MEK dispersion of surface-modified silica particles, and a methyl ethyl ketone dispersion of surface-modified silica particles were prepared by carrying out the same operations as in steps (a) to (c) of Example 1-1 , except that after the addition of DMMPS in step (b) of Example 1-1, DTMS was additionally added so that the amount of DTMS was 1.0 particle per nm2 of the surface area of the silica particles contained in the silica sol, the mixture was maintained at 60° C. for 3 hours, and then HMDS was added.
  • Examples 1 to 4 660 g of the water-dispersed silica sol c prepared in Synthesis Example 1 was diluted with methanol to 1,000 g, and this was placed in a 2 L eggplant-shaped flask-equipped evaporator, and then methanol was gradually added while distilling off water at 120° C. and 580 Torr, thereby replacing the water, which was the dispersion medium, with methanol. When the water content of the methanol dispersion became 3.0 mass % or less, the replacement was terminated, and 1,000 g of methanol-dispersed silica sol was obtained.
  • the resulting methanol-dispersed silica sol had a silica concentration of 13.2% by mass, a water content of 1.6% by mass, and a viscosity of 0.9 mPa ⁇ s.
  • 20 g of the obtained methanol-dispersed silica sol was placed in a 100-mL eggplant-shaped flask, and while stirring with a magnetic stirrer, 3.0 g of methyl ethyl ketone (MEK) and DTMS were added in an amount that would result in 3 particles per 1 nm2 of the surface area of the silica particles as determined by the nitrogen adsorption method, and the mixture was heated to 60°C and held for 3 hours.
  • MEK methyl ethyl ketone
  • HMDS was added in an amount that would result in 5 particles per 1 nm2 of the surface area of the silica particles, and the mixture was heated to 60°C and held for 3 hours. Then, diisopropylamine was added so that the pH (1+1+1) was 8.0 to 10.0, and the mixture was heated to 60°C and held for 1 hour to prepare a methanol/MEK dispersion of surface-modified silica particles.
  • the recovery flask containing the methanol/MEK dispersion of the surface-modified silica particles was set in a rotary evaporator, and distillation was performed while supplying methyl ethyl ketone at a bath temperature of 80°C and a reduced pressure of 550 to 350 Torr, replacing the dispersion medium with methyl ethyl ketone to obtain a methyl ethyl ketone dispersion of the surface-modified silica particles.
  • the obtained methyl ethyl ketone dispersion of the surface-modified silica particles had a silica concentration of 10.1% by mass, a water content of 0.1% by mass or less, and a methanol content of 0.1% by mass or less.
  • Examples 1 to 5 660 g of the water-dispersed silica sol c prepared in Synthesis Example 1 was diluted with methanol to 1,000 g, and this was placed in a 2 L eggplant-shaped flask-equipped evaporator, and then water was distilled off at 120° C. and 580 Torr while gradually adding methanol, thereby replacing the water, which was the dispersion medium, with methanol. When the water content of the methanol dispersion became 3.0 mass % or less, the replacement was stopped, and 1,000 g of methanol-dispersed silica sol was obtained.
  • the resulting methanol-dispersed silica sol had a silica concentration of 13.2% by mass, a water content of 1.6% by mass, and a viscosity of 0.9 mPa ⁇ s.
  • 20 g of the obtained methanol-dispersed silica sol was placed in a 100-mL eggplant-shaped flask, and while stirring with a magnetic stirrer, 3.0 g of methyl ethyl ketone (MEK) and DMMPS were added in an amount that would result in 6 particles per 1 nm2 of the surface area of the silica particles as determined by the nitrogen adsorption method, and the mixture was heated to 60°C and held for 3 hours.
  • MEK methyl ethyl ketone
  • HMDS was added in an amount that would result in 5 particles per 1 nm2 of the surface area of the silica particles, and the mixture was heated to 60°C and held for 3 hours. Then, diisopropylamine was added so that the pH (1+1+1) was 8.0 to 10.0, and the mixture was heated to 60°C and held for 1 hour to prepare a methanol/MEK dispersion of surface-modified silica particles.
  • the recovery flask containing the methanol/MEK dispersion of the surface-modified silica particles was set in a rotary evaporator, and distillation was performed while supplying methyl ethyl ketone at a bath temperature of 80°C and a reduced pressure of 550 to 350 Torr, replacing the dispersion medium with methyl ethyl ketone to obtain a methyl ethyl ketone dispersion of the surface-modified silica particles.
  • the obtained methyl ethyl ketone dispersion of the surface-modified silica particles had a silica concentration of 10.3% by mass, a water content of 0.1% by mass or less, and a methanol content of 0.1% by mass or less.
  • Example 1-1 1,000 g of the methanol-dispersed silica sol obtained in step (a) of Example 1-1 was placed in a 2-liter eggplant-shaped flask, and while stirring with a magnetic stirrer, 150 g of methyl ethyl ketone and an amount of DMMPS such that the number of particles becomes 3 per 1 nm2 of the surface area of the silica particles determined by a nitrogen adsorption method were added, and the mixture was heated to 60° C. and maintained for 3 hours. Thereafter, diisopropylamine was added so that the pH (1+1+1) became 8.0 to 10.0, and the mixture was heated to 60° C.
  • Comparative Example 1-2 A methyl ethyl ketone dispersion of surface-modified silica particles was prepared by carrying out the same operation as in Comparative Example 1-1, except that 5 particles of HMDS per 1 nm2 of the surface area of the silica particles contained in the silica sol were added instead of DMMPS in Comparative Example 1-1.
  • Comparative Examples 1 to 4 water-dispersed silica sol b was used.
  • Example 2-1 The methyl ethyl ketone dispersion of the surface-modified silica particles obtained in Example 1-1 was dried in a vacuum dryer at 100° C., and the obtained silica gel was pulverized in a mortar and further dried at 150° C. for 1 hour to prepare silica powder.
  • the dielectric constant and dielectric loss tangent of the obtained silica powder were measured at 23° C. and a frequency of 1 GHz.
  • the dielectric properties of the surface-modified silica particles are shown in Table 2.
  • Example 2-2 to 2-5 Comparative Examples 2-1 to 2-4
  • silica powders were prepared in the same manner as in Example 2-1, and the dielectric constant and dielectric loss tangent were measured.
  • the dielectric properties of the surface-modified silica particles are shown in Table 2.
  • Example 3-1 The methyl ethyl ketone dispersion of the surface-modified silica particles obtained in Example 1-1 was dried in a vacuum dryer at 100° C. to prepare silica powder. The hydrophobicity of the obtained silica powder was measured. The hydrophobicity of the surface-modified silica particles is shown in Table 2.
  • Examples 3-2 to 3-5, Comparative Examples 3-1 to 3-4 For the methyl ethyl ketone dispersions of the surface-modified silica particles obtained in Examples 1-2 to 1-5 and Comparative Examples 1-1 to 1-3 and the water-dispersed silica sol b in Comparative Example 1-4, silica powders were prepared in the same manner as in Example 3-1, and the hydrophobicity was measured. The hydrophobicity of the surface-modified silica particles is shown in Table 2.
  • Example 4-1 The hexane compatibility of the methyl ethyl ketone dispersion of the surface-modified silica particles obtained in Example 1-1 was confirmed. The hexane compatibility of the surface-modified silica particles is shown in Table 2.
  • Example 4-2, Comparative Example 4-1 The hexane compatibility of the methyl ethyl ketone dispersions of the surface-modified silica particles obtained in Example 1-3 and Comparative Example 1-1 was confirmed. The hexane compatibility of the surface-modified silica particles is shown in Table 2.
  • Example 5-1 The compatibility of the surface-modified silica particles and an organic resin material (maleimide resin) was confirmed for the surface-modified silica particles obtained in Example 1-1.
  • 50 g of the methyl ethyl ketone dispersion of the surface-modified silica particles obtained in Example 1-1 was charged into a 300-milliliter eggplant-shaped flask, and 20 g of a low-viscosity liquid maleimide resin (maleimide-terminated polyimide resin, product name: BMI-689, 1000 to 2000 cP (25° C.), manufactured by DMI Co., Ltd.) was added while stirring with a magnetic stirrer.
  • a low-viscosity liquid maleimide resin maleimide-terminated polyimide resin, product name: BMI-689, 1000 to 2000 cP (25° C.), manufactured by DMI Co., Ltd.
  • the eggplant-shaped flask containing the mixture of the obtained methyl ethyl ketone dispersion of the surface-modified silica particles and the maleimide resin was set in a rotary evaporator, and distillation was performed at a bath temperature of 80° C. and a reduced pressure of 400 to 30 Torr, and the dispersion medium was replaced from methyl ethyl ketone to maleimide resin, thereby obtaining a maleimide resin dispersion of the surface-modified silica particles.
  • the obtained maleimide resin dispersion of surface-modified silica particles had a silica concentration of 30.4% by mass, a water content of 0.1% by mass or less, a methanol content of 0.1% by mass or less, a methyl ethyl ketone content of 0.1% by mass or less, a viscosity of 6000 to 7000 cP (B-type viscometer, temperature 25°C), an average dispersed particle size measured by dynamic light scattering (hereinafter referred to as dynamic light scattering particle size) of 79.2 nm, and a yellow transparent appearance.
  • the obtained maleimide resin dispersion of surface-modified silica particles showed no change in appearance even after being left to stand at room temperature for one week, and no precipitate was formed.
  • the obtained maleimide resin dispersion of surface-modified silica particles was applied to a glass substrate degreased with acetone using a hand-applied bar coater (gap: 25 ⁇ m), baked for 30 minutes on a hot plate heated to 100° C. under a nitrogen atmosphere, and then baked for 120 minutes after raising the temperature of the hot plate to 230° C. to obtain a cured film of a composite material containing surface-modified silica particles and maleimide resin (see FIG. 1(B)).
  • the obtained cured film was yellow and transparent, and no repellency was observed with the glass substrate (note that in FIG. 1, the periphery of the portion where the resin dispersion and the low-viscosity liquid maleimide resin described below were applied is indicated by a black frame for reference).
  • the film thickness was measured with a constant pressure thickness meter (manufactured by Teclock Corporation, model: PG-01A) and was 19 ⁇ m.
  • the above-mentioned low-viscosity liquid maleimide resin product name: BMI-689 alone was used and applied to a glass substrate degreased with acetone using a hand-applied bar coater (gap: 25 ⁇ m), followed by baking for 30 minutes on a hot plate heated to 100° C. under a nitrogen atmosphere, and then further increasing the temperature of the hot plate to 230° C. and baking for 120 minutes, thereby obtaining a cured film of only the maleimide resin (see FIG. 1(A)).
  • the obtained cured film was yellow and transparent, but repelling from the glass substrate was observed.
  • Example 5-2 The compatibility of the surface-modified silica particles and an organic resin material (epoxy resin) was confirmed for the surface-modified silica particles obtained in Example 1-1.
  • 50 g of the methyl ethyl ketone dispersion of the surface-modified silica particles obtained in Example 1-1 was charged into a 300-milliliter eggplant-shaped flask, and 20 g of an epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., bisphenol A-type epoxy resin, product name: YD-8125, 3900 to 5300 cP) was added while stirring with a magnetic stirrer.
  • an epoxy resin manufactured by Nippon Steel Chemical & Material Co., Ltd., bisphenol A-type epoxy resin, product name: YD-8125, 3900 to 5300 cP
  • the eggplant-shaped flask containing the mixture of the obtained methyl ethyl ketone dispersion of the surface-modified silica particles and the epoxy resin was set in a rotary evaporator, and distillation was performed at a bath temperature of 80° C. and a reduced pressure of 400 to 30 Torr, and the dispersion medium was entirely replaced from methyl ethyl ketone to epoxy resin, thereby obtaining an epoxy resin dispersion of the surface-modified silica particles.
  • the obtained epoxy resin dispersion of surface-modified silica particles had a silica concentration of 32.1% by mass, a water content of 0.1% by mass or less, a methanol content of 0.1% by mass or less, a methyl ethyl ketone content of 0.1% by mass or less, a viscosity of 14,000 to 16,000 cP (B-type viscometer, temperature 25° C.), an average dispersed particle size measured by dynamic light scattering method (hereinafter, dynamic light scattering particle size) of 78.7 nm, and an epoxy equivalent of 264 g/eq (in accordance with JIS K7236), and was white and transparent in appearance. Furthermore, the obtained epoxy resin dispersion of surface-modified silica particles showed no change in appearance even after being left to stand at room temperature for one week, and no precipitate was formed.
  • the surface-modified silica particles of Examples 1-1 to 1-5 had an average primary particle size of 5 nm to 500 nm, a dielectric loss tangent value of less than 0.01 at a frequency of 1 GHz (Examples 2-1 to 2-5), and a hydrophobicity degree (%) of 40 or more (Examples 3-1 to 3-5), confirming that they achieved both low dielectric properties and high hydrophobicity.
  • the surface-modified silica particles of Examples 1-1 to 1-5 had a water vapor adsorption surface area/nitrogen adsorption surface area (S H2O /S N2 ) of 0.6 or less and a total silanol group ratio of 5% or less in the silica particles (silica sol a, silica sol c) before surface modification, and were surface-modified silica particles treated with at least two different surface modifiers.
  • S H2O /S N2 water vapor adsorption surface area/nitrogen adsorption surface area
  • the surface-modified silica particles of Comparative Examples 1-1 and 1-2 had an average primary particle size of 5 nm to 500 nm and a dielectric loss tangent value of less than 0.01 at a frequency of 1 GHz (Comparative Examples 2-1 to 2-2), but had a hydrophobicity (%) of less than 40 (Comparative Examples 3-1 to 3-2), making them silica particles with poor hydrophobicity.
  • the surface-modified silica particles of Comparative Examples 1-1 and 1-2 had a water vapor adsorption surface area/nitrogen adsorption surface area (S H2O /S N2 ) of the silica particles (silica sol a) before surface modification of 0.6 or less and a total silanol group ratio of 5% or less, and the surface-modified silica particles were 5% or less, but were surface-modified silica particles treated with one type of surface modifier.
  • S H2O /S N2 water vapor adsorption surface area/nitrogen adsorption surface area
  • the surface-modified silica particles of Comparative Example 1-3 had an average primary particle diameter of 5 nm to 500 nm and a hydrophobicity degree (%) of 40 or more (Comparative Example 3-3), but the dielectric tangent value at a frequency of 1 GHz was significantly greater than 0.01 (Comparative Example 2-3), and the silica particles did not satisfy the low dielectric characteristic.
  • the surface-modified silica particles of Comparative Example 1-3 were silica particles treated with at least two different surface modifiers, and the water vapor adsorption surface area/nitrogen adsorption surface area (S H2O /S N2 ) of the silica particles (silica sol c) before surface modification was 0.6 or more, and the total silanol group ratio was 5% or more.
  • the silica particles of Comparative Example 1-4 i.e., the unmodified silica particles, had an average primary particle diameter of 5 nm to 500 nm, but the dielectric tangent value at a frequency of 1 GHz was significantly greater than 0.01 (Comparative Example 2-4), and the hydrophobicity (%) was 0 (Comparative Example 3-4).
  • the results shown in the comparative examples above indicate that it is not easy to realize nano-order silica particles that have both a low dielectric tangent and a high degree of hydrophobicity.
  • Example 1-1 and Example 1-3 which are methyl ethyl ketone dispersions containing surface-modified silica particles with a hydrophobicity of 40 or more, were judged to be OK in terms of hexane compatibility (Examples 4-1 and 4-2).
  • the hydrophobic silica particles according to the present invention are particles that realize a high hydrophobicity of 40% or more and reduce the dielectric loss tangent of conventional hydrophobic silica sol to less than half.
  • the hydrophobicity can be improved by 20% or more while maintaining the low dielectric loss tangent of surface-modified silica particles coated with a single surface modifier, making them suitable not only for use in composite materials but also for use in high frequency applications.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Inorganic Chemistry (AREA)
  • Silicon Compounds (AREA)

Abstract

L'invention fournit des particules de silice de facteur de pertes diélectriques à 1GHz inférieur à 0,01, et de degré d'hydrophobicité supérieur ou égal à 40%, et fournit également une dispersion liquide de ces particules de silice. Plus précisément, l'invention concerne des particules de silice modifiées en surface de degré d'hydrophobicité supérieur ou égal à 40% qui sont caractéristiques en ce qu'elles présentent un diamètre moyen de particules primaires compris entre ５ et ５００ｎｍ, et un facteur de pertes diélectriques à 1GHz inférieur à 0,01.
PCT/JP2023/039319 2022-10-31 2023-10-31 Sol de silice à faible facteur de pertes diélectriques rendu hydrophobe, et procédé de fabrication de celui-ci WO2024096021A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012136363A (ja) * 2010-12-24 2012-07-19 Kao Corp 中空シリカ粒子
JP2014214061A (ja) * 2013-04-26 2014-11-17 株式会社トクヤマ 疎水性無機酸化物粉末及びその製造方法
JP2016079061A (ja) * 2014-10-15 2016-05-16 株式会社アドマテックス 無機フィラー及びその製造方法、樹脂組成物、及び成形品
JP2020097498A (ja) * 2018-12-17 2020-06-25 株式会社アドマテックス 電子材料用フィラー及びその製造方法、電子材料用樹脂組成物の製造方法、高周波用基板、並びに電子材料用スラリー
WO2020195205A1 (fr) * 2019-03-26 2020-10-01 デンカ株式会社 Poudre de silice sphérique
WO2023145780A1 (fr) * 2022-01-28 2023-08-03 日産化学株式会社 Sol de silice à faible tangente diélectrique, et méthode de production de sol de silice à faible tangente diélectrique

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012136363A (ja) * 2010-12-24 2012-07-19 Kao Corp 中空シリカ粒子
JP2014214061A (ja) * 2013-04-26 2014-11-17 株式会社トクヤマ 疎水性無機酸化物粉末及びその製造方法
JP2016079061A (ja) * 2014-10-15 2016-05-16 株式会社アドマテックス 無機フィラー及びその製造方法、樹脂組成物、及び成形品
JP2020097498A (ja) * 2018-12-17 2020-06-25 株式会社アドマテックス 電子材料用フィラー及びその製造方法、電子材料用樹脂組成物の製造方法、高周波用基板、並びに電子材料用スラリー
WO2020195205A1 (fr) * 2019-03-26 2020-10-01 デンカ株式会社 Poudre de silice sphérique
WO2023145780A1 (fr) * 2022-01-28 2023-08-03 日産化学株式会社 Sol de silice à faible tangente diélectrique, et méthode de production de sol de silice à faible tangente diélectrique

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