JP5907092B2 - Method for producing metal silicon powder - Google Patents

Description

  The present invention is a metal silicon powder having excellent fluidity, easy powder operations such as transportation, classification, and coarse particle cutting, suppressing aggregation when mixed with a resin, and excellent dispersibility. The present invention relates to a resin composition.

  When sealing and fixing electronic parts and fixing machine parts, etc., it may be performed using a resin composition, and in order to give high thermal conductivity, a resin composition mixed with metal fine powder is used. May be used. In this case, examples of the metal fine powder to be mixed include metal silicon powder, and those having a particle size on the order of μm are preferably used.

  When such fine metal silicon powder is mixed in the resin, the handling becomes a problem. Metallic silicon powder has a problem that handling is poor because aggregation and the like proceed in the same manner as other fine metal powders.

  According to the method described in Patent Document 1, when metal silicon powder is treated with a basic substance, oxygen atoms (derived from a silica-based oxide) present on the surface of the metal silicon powder interact with the basic substance. The basic substance can be stably adhered to the surface of the metal silicon powder, and the presence of the basic substance causes the metal silicon powder powders to repel each other due to electrostatic repulsion. And agglomeration of the powder can be prevented. However, it is difficult to control the silica-based oxide layer on the surface of the metal silicon, and the reaction rate between the silica-based oxide layer and hexamethyldisilazane is poor. Large amounts of hexamethyldisilazane must be used to improve. There was also a problem that the cost and process were complicated.

JP 2010-254511 A

  The present invention has been made in view of the above circumstances, and includes a metal silicon powder excellent in operability of powder operation such as transport and classification of metal silicon powder and dispersibility in a resin, and the metal silicon composition. It aims at providing a resin composition.

  As a result of intensive studies to solve the above problems, the present inventors have reached the present invention. That is, the present invention is as follows.

<1> A powder in which silica fine particles having an amount of at least 0.01% by mass of the mass of the metal silicon powder are adhered to the surface of the metal silicon powder,
The silica fine particles are
(A1) a step of obtaining hydrophilic spherical silica fine particles substantially consisting of SiO ₂ units by hydrolyzing and condensing a tetrafunctional silane compound, a partially hydrolyzed condensation product thereof, or a mixture thereof;
(A2) R ¹ SiO _3/2 units (wherein R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms) are introduced onto the surface of the hydrophilic spherical silica fine particles. Process,
(A3) introducing a R ² ₃ SiO _1/2 unit (wherein each R ² is the same or different and is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms). Hydrophobic spherical silica fine particles (1) produced by the method, having a particle size in the range of 0.005 to 1.0 μm, a particle size distribution D90 / D10 value of 3 or less, and an average circularity of 0.8 to 1. A powder characterized by that.

<2> The hydrophobic spherical silica fine particles (1)
(A1) General formula (I):
Si (OR ³ ) ₄ (I)
(Wherein each R ³ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms), a tetrafunctional silane compound, a partial hydrolysis product thereof, or a mixture thereof, In the presence of a substance, a mixed solvent dispersion of hydrophilic spherical silica fine particles substantially consisting of SiO ₂ units is obtained by hydrolysis and condensation in a mixed liquid of a hydrophilic organic solvent and water,
(A2) In the mixed solvent dispersion of the obtained hydrophilic spherical silica fine particles, the general formula (II):
R ¹ Si (OR ⁴ ) ₃ (II)
Wherein R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and each R ⁴ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms. trifunctional silane compound, a partial hydrolysis product, or by treating the surface of the hydrophilic spherical silica microparticles by adding these mixtures, the surface of the hydrophilic spherical silica microparticles R ¹ SiO 3 _{/ 2} units (R ¹ is as described above) were introduced to obtain a mixed solvent dispersion of the first hydrophobic spherical silica fine particles,
(A3) In the mixed solvent dispersion of the obtained first hydrophobic spherical silica fine particles, the general formula (III):
R ² ₃ SiNHSiR ² ₃ (III)
(In the formula, each R ² is the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms)
Silazane compounds represented by general formula (IV):
R ² ₃ SiX (IV)
(Wherein R ² is as defined in formula (III), X is an OH group or a hydrolyzable group), or a mixture thereof, The surface of the first hydrophobic spherical silica fine particles is treated thereby, and R ² ₃ SiO _1/2 units (R ² is defined by the general formula (III) are formed on the surface of the first hydrophobic spherical silica fine particles. The powder according to <1>, which is a hydrophobic spherical silica fine particle obtained as a second hydrophobic silica fine particle by introducing

  <3> The powder according to <2>, wherein the mixed solvent dispersion of the first hydrophobic spherical silica fine particles obtained in the step (A2) is concentrated before being subjected to the step (A3).

  <4> The hydrophobic spherical silica fine particles (1) are added to the metal silicon powder in an amount of 0.01 to 5.0% by mass of the mass of the metal silicon powder, mixed, and the hydrophobic spherical silica fine particles ( The powder according to any one of <1> to <3>, wherein 1) is adhered to the surface of the metal silicon powder.

<5> A resin composition obtained by adding 0.01 to 600 parts by mass of the powder according to any one of <1> to <4> with respect to 100 parts by mass of the resin.
<6> The resin is an epoxy resin, silicone resin, phenol resin, melamine resin, urea resin, unsaturated polyester, fluororesin; polyamide such as polyimide, polyamideimide, or polyetherimide; polyester such as polybutylene terephthalate or polyethylene terephthalate Polyphenylene sulfide, wholly aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide modified resin, ABS resin, AAS (acrylonitrile / acrylic rubber / styrene) resin, AES (acrylonitrile / ethylene / propylene / diene rubber / styrene) The resin composition according to <5>, which is one or more selected from resins.
<7> A heat transfer sheet produced by molding the resin composition according to <5> or <6>.

  Since the metal silicon powder according to the present invention is excellent in fluidity, the operability of the metal silicon powder such as classification and transportation is improved, and the dispersibility is also excellent, so that the resin has high thermal conductivity, high electrical conductivity, etc. Performance can be imparted.

The electron micrograph of the powder which spherical hydrophobic silica fine particles adhered to the metal silicon powder surface of Example 2 is shown. The electron micrograph of the powder which spherical hydrophobic silica fine particles adhered to the metal silicon powder surface of Example 4 is shown. The electron micrograph of the untreated metal silicon powder which is not making spherical hydrophobic silica fine particles adhere to the metal silicon powder surface of the comparative example 5 is shown.

Hereinafter, the present invention will be described in detail.
<Metal silicon powder component>
The particle size of the metal silicon powder is not particularly limited, but the volume average particle size is preferably 1 μm to 30 μm, particularly preferably 1 to 20 μm. Moreover, it is preferable that the coarse grain of 45 micrometers or more is not included substantially.

  The kind of metal silicon powder is not particularly limited. For example, it may be produced by pulverizing metallic silicon of any form, or may be produced from molten metallic silicon by an atomizing method. Since the particle size of the metal silicon powder has a high correlation with the particle size of the metal silicon composition to be produced, the particle size distribution is adjusted so that the particle size required for the metal silicon composition of the present invention is obtained. The particle size distribution can be adjusted by changing the powder production conditions and classifying the obtained powder. Further, in the stage of metal silicon powder, the particle size distribution is not adjusted by classification or the like, and the classification operation can be performed after the metal silicon composition of the present invention is obtained. The purity of the metal silicon powder is determined according to the purpose for which the metal silicon composition is used. When the metal silicon powder in the metal silicon composition is required to have a high purity, the metal silicon powder should also have a high purity, and when such a purity is not required, Purity is also adopted depending on the degree.

<Hydrophobic spherical silica fine particles>
The characteristics of the hydrophobic spherical silica fine particles attached to the metal silicon powder will be described in detail.
The hydrophobic spherical silica fine particles used in the present invention are
(A1) obtaining hydrophilic spherical silica fine particles substantially composed of SiO ₂ units by hydrolyzing and condensing a tetrafunctional silane compound, a partial hydrolysis-condensation product thereof, or a combination thereof;
(A2) R ¹ SiO _3/2 units (wherein R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms) are introduced onto the surface of the hydrophilic spherical silica fine particles. Process,
(A3) introducing a R ² ₃ SiO _1/2 unit (wherein each R ² is the same or different and is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms). Manufactured by the method,
Hydrophobic spherical silica fine particles (1) having a particle size in the range of 0.005 to 1.0 μm, a particle size distribution D90 / D10 of 3 or less and an average circularity of 0.8 to 1.

  The hydrophobic spherical silica fine particles have a particle size of 0.005 to 1.0 μm, preferably 0.01 to 0.30 μm, particularly preferably 0.03 to 0.20 μm. When this particle diameter is smaller than 0.005 μm, the metal silicon powder is agglomerated so that it may not be taken out well. Moreover, when larger than 1.0 micrometer, favorable fluidity | liquidity and a filling property may not be provided to metal silicon powder, but it is unpreferable.

The value of D90 / D10, which is an index of the particle size distribution of the hydrophobic spherical silica fine particles, is 3 or less. Here, D10 and D90 are values obtained by measuring the particle size distribution. When the particle size distribution of the powder is measured, the particle size that becomes 10% cumulative from the smaller side is called D10, and the particle size that becomes 90% cumulative from the smaller side is called D90. Since D90 / D10 is 3 or less, the particle size distribution of the metal silicon powder in the present invention is sharp. Thus, when the particle size distribution is sharp, it is preferable in terms of easy control of the fluidity of the metal silicon powder. The D90 / D10 is more preferably 2.9 or less.
In the present invention, the particle size distribution of the fine particles is measured by a dynamic light scattering method / laser Doppler nanotrack particle size distribution measuring apparatus (trade name: UPA-EX150, manufactured by Nikkiso Co., Ltd.), and the volume-based median diameter is The particle diameter was taken. The median diameter is a particle diameter corresponding to 50% cumulative when the particle size distribution is expressed as a cumulative distribution.

  The average circularity of the hydrophobic spherical silica fine particles is preferably from 0.8 to 1, more preferably from 0.92 to 1. Here, “spherical” includes not only a true sphere but also a slightly distorted sphere. Such a “spherical” shape is evaluated by the circularity when the particles are projected two-dimensionally, and the circularity is in the range of 0.8 to 1. Here, the circularity is (peripheral length of a circle equal to the particle area) / (peripheral length of particle). This circularity can be measured by image analysis of a particle image obtained with an electron microscope or the like.

In the above, the hydrophilic spherical silica fine particles “consisting essentially of SiO ₂ units” means that the fine particles are basically composed of SiO ₂ units, but are not composed only of the units, It means having a large number of silanol groups at least on the surface as is generally known. In some cases, the hydrolyzable group (hydrocarbyloxy group) derived from the tetrafunctional silane compound as a raw material and / or its partial hydrolysis-condensation product is not partially converted into a silanol group, but a slight amount of fine particles as it is. It means that it may remain on the surface or inside.

  As described above, in the present invention, a small particle size sol-gel method silica obtained by hydrolysis of tetraalkoxysilane is used as a silica base (silica before hydrophobization treatment), and by performing a specific surface treatment thereto, When obtained as a powder, the particle size after hydrophobization treatment maintains the primary particle size of the silica base, is not agglomerated, has a small particle size, and gives good fluidity to the metal silicon powder Hydrophobic silica fine particles are obtained.

  Use of tetraalkoxysilane having a small number of carbon atoms in the alkoxy group as a silica particle having a small particle diameter, use of an alcohol having a small number of carbon atoms as a solvent, increasing the hydrolysis temperature, during hydrolysis of tetraalkoxysilane By changing the reaction conditions such as lowering the concentration of the catalyst and lowering the concentration of the hydrolysis catalyst, a silica raw material having an arbitrary particle size can be obtained.

  As described above and as will be described in more detail below, the silica particle having a small particle diameter is subjected to a specific surface treatment to obtain desired hydrophobic silica fine particles.

  One method for producing hydrophobic spherical silica fine particles will be described in detail below.

<Production method A)>
According to this method, the hydrophobic spherical silica fine particles of the present invention are
Step (A1): Step of synthesizing hydrophilic spherical silica fine particles,
Step (A2): Surface treatment step with a trifunctional silane compound,
Step (A3): Obtained by a surface treatment step with a functional silane compound. Hereinafter, each process is demonstrated one by one.

Step (A1): Synthesis step of hydrophilic spherical silica fine particles General formula (I):
Si (OR ³ ) ₄ (I)
(Wherein each R ³ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms), a tetrafunctional silane compound, a partial hydrolysis product thereof, or a mixture thereof, Hydrolysis and condensation in a mixed liquid of a hydrophilic organic solvent containing a hydrophilic substance and water can provide a mixed solvent dispersion of hydrophilic spherical silica fine particles.

In the above general formula (I), R ³ is a monovalent hydrocarbon group having 1 to 6 carbon atoms, preferably a monovalent hydrocarbon group having 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms. is there. Examples of the monovalent hydrocarbon group represented by R ³ include an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group; and an aryl group such as a phenyl group, preferably a methyl group, An ethyl group, a propyl group, or a butyl group, particularly preferably a methyl group or an ethyl group.

  Examples of the tetrafunctional silane compound represented by the general formula (I) include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane; and tetraphenoxysilane, preferably , Tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane and tetrabutoxysilane, particularly preferably tetramethoxysilane and tetraethoxysilane. Examples of the partial hydrolysis-condensation product of the tetrafunctional silane compound represented by the general formula (I) include alkyl silicates such as methyl silicate and ethyl silicate.

The hydrophilic organic solvent is not particularly limited as long as it dissolves the tetrafunctional silane compound represented by the general formula (I), the partial hydrolysis-condensation product, and water. For example, alcohols Cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate; ketones such as acetone and methylethylketone; ethers such as dioxane and tetrahydrofuran, and the like, preferably alcohols and cellosolves. Examples include alcohols. Examples of the alcohols include general formula (V):
R ⁵ OH (V)
[Wherein, R ⁵ is a monovalent hydrocarbon group having 1 to 6 carbon atoms].

In the general formula (V), R ⁵ is preferably a monovalent hydrocarbon group having 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms. Examples of the monovalent hydrocarbon group represented by R ⁵ include alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group, preferably a methyl group, an ethyl group, a propyl group, and an isopropyl group. Preferably a methyl group and an ethyl group are mentioned. Examples of the alcohol represented by the general formula (V) include methanol, ethanol, propanol, isopropanol, butanol and the like, preferably methanol and ethanol. As the number of carbon atoms in the alcohol increases, the particle size of the spherical silica fine particles to be generated increases. Therefore, methanol is preferred in order to obtain the desired small particle size silica fine particles.

Examples of the basic substance include ammonia, dimethylamine, diethylamine and the like, preferably ammonia, diethylamine, and particularly preferably ammonia. These basic substances may be dissolved in water in a required amount, and the obtained aqueous solution (basic) may be mixed with the hydrophilic organic solvent.
The amount of the basic substance used is 0.01 to 2 mol with respect to a total of 1 mol of the hydrocarbyloxy group of the tetrafunctional silane compound represented by the general formula (I) and / or its partial hydrolysis-condensation product. Is more preferable, 0.02 to 0.5 mol is more preferable, and 0.04 to 0.12 mol is particularly preferable. At this time, the smaller the amount of the basic substance, the desired small particle size silica fine particles.

  The amount of water used in the hydrolysis and condensation is from 0.5 to a total of 1 mol of the hydrocarbyloxy group of the tetrafunctional silane compound represented by the general formula (I) and / or the partial hydrolysis condensation product thereof. 5 mol is preferable, 0.6 to 2 mol is more preferable, and 0.7 to 1 mol is particularly preferable. The ratio of the hydrophilic organic solvent to water (hydrophilic organic solvent: water) is preferably 0.5 to 10, more preferably 3 to 9, and particularly preferably 5 to 8 in terms of mass ratio. . As the amount of the hydrophilic organic solvent increases, silica particles having a desired small particle diameter can be obtained.

  Hydrolysis and condensation of the tetrafunctional silane compound represented by the general formula (I) can be carried out by a well-known method, that is, in a mixture of a hydrophilic organic solvent containing a basic substance and water in the general formula (I). It is performed by adding a tetrafunctional silane compound or the like shown.

  The concentration of silica fine particles in the mixed solvent dispersion of hydrophilic spherical silica fine particles obtained in this step (A1) is generally 3 to 15% by mass, preferably 5 to 10% by mass.

Step (A2): Surface treatment step with a trifunctional silane compound In the mixed solvent dispersion of the hydrophilic spherical silica fine particles obtained in the step (A1), the general formula (II):
R ¹ Si (OR ⁴ ) ₃ (II)
Wherein R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and each R ⁴ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms. To the surface of the hydrophilic spherical silica fine particles by adding a trifunctional silane compound or a partial hydrolysis product thereof, or a mixture thereof, and treating the surface of the hydrophilic spherical silica fine particles thereby. ¹ SiO _3/2 unit (R ¹ is as described above) is introduced to obtain a mixed solvent dispersion of the first hydrophobic spherical silica fine particles.

  This step (A2) is indispensable for suppressing aggregation of silica fine particles in the subsequent concentration step. If the aggregation cannot be suppressed, the individual particles of the obtained silica-based powder cannot maintain the primary particle diameter, and the fluidity imparting ability is deteriorated.

In the general formula (II), R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 3 carbon atoms, particularly preferably 1 to 2 carbon atoms. Is a valent hydrocarbon group. Examples of the monovalent hydrocarbon group represented by R ¹ include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, butyl group and hexyl group, preferably methyl group, ethyl group, n -A propyl group or an isopropyl group, particularly preferably a methyl group or an ethyl group. Further, some or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine atom, chlorine atom, bromine atom, preferably fluorine atom.

In the general formula (II), R ⁴ is a monovalent hydrocarbon group having 1 to 6 carbon atoms, preferably a monovalent hydrocarbon group having 1 to 3 carbon atoms, particularly preferably 1 to 2 carbon atoms. is there. Examples of the monovalent hydrocarbon group represented by R ⁴ include alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group, preferably a methyl group, an ethyl group, or a propyl group, and particularly preferably a methyl group. Or an ethyl group is mentioned.

  Examples of the trifunctional silane compound represented by the general formula (II) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, and n-propyltriethoxy. Unsubstituted or halogen-substituted trisilane such as silane, isopropyltrimethoxysilane, isopropyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, trifluoropropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane Alkoxysilane, etc., preferably methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane and ethyltriethoxysilane, more preferably methyltrimethoxysilane And methyl triethoxysilane, or they partially hydrolyzed condensation products thereof.

  The addition amount of the trifunctional silane compound represented by the general formula (II) is 0.001 to 1 mol, preferably 0.01 to 0.1 mol, particularly preferably 0.01 to 0.05, per mol of Si atom of the used hydrophilic spherical silica fine particles. Is a mole. If the amount added is less than 0.01 mol, the dispersibility of the resulting hydrophobic spherical silica fine particles will deteriorate, so that the effect of imparting fluidity to the metal silicon powder will not appear, and if it exceeds 1 mol, the silica fine particles may aggregate. .

  The concentration of the silica fine particles in the mixed solvent dispersion of the first hydrophobic spherical silica fine particles obtained here is usually 3% by mass or more and less than 15% by mass, preferably 5 to 10% by mass. If the concentration is too low, there is an inconvenience that productivity is lowered, and if it is too high, there is an inconvenience that silica fine particles are aggregated.

-Concentration step The first hydrophobic spherical silica is obtained by removing a portion of the hydrophilic organic solvent and water from the mixed solvent dispersion of the first hydrophobic spherical silica fine particles thus obtained and concentrating. A mixed solvent concentrated dispersion of fine particles is obtained. At this time, the hydrophobic organic solvent may be added in advance (before the concentration step) or during the concentration step. In this case, the hydrophobic solvent used is preferably a hydrocarbon or ketone solvent. Specific examples of the solvent include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone and the like, and methyl isobutyl ketone is preferable. Examples of the method for removing a part of the hydrophilic organic solvent and water include distillation and distillation under reduced pressure. The resulting concentrated dispersion preferably has a silica fine particle concentration of 15 to 40% by mass, more preferably 20 to 35% by mass, and particularly preferably 25 to 30% by mass. If the amount is less than 15% by mass, the surface treatment in the subsequent process may not proceed smoothly. If the amount is more than 40% by mass, the silica fine particles may be aggregated.

  In the concentration step, the silazane compound represented by the general formula (III) and the monofunctional silane compound represented by the general formula (IV) used as a surface treatment agent in the next step (A3) react with alcohol or water. In addition, the surface treatment becomes insufficient, and when the subsequent drying is performed, aggregation occurs, and the resulting silica powder cannot maintain the primary particle diameter, and has the significance of suppressing problems such as poor fluidity imparting ability. is there.

Step (A3): Surface treatment step with a functional silane compound In the mixed solvent dispersion of the first hydrophobic spherical silica fine particles obtained in the step (A2), the general formula (III):
R ² ₃ SiNHSiR ² ₃ (III)
(In the formula, each R ² is the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms)
Or a general formula (IV):
R ² ₃ SiX (IV)
(Wherein R ² is as defined in the general formula (III) and X is an OH group or a hydrolyzable group), and a monofunctional silane compound or a mixture thereof is added. By treating the surface of the first hydrophobic spherical silica fine particles and introducing R ² ₃ SiO _1/2 units (wherein R ² is as defined in the general formula (III)) to the surface of the fine particles, Two hydrophobic spherical silica fine particles are obtained. By the treatment in this step, R ² ₃ SiO _1/2 units are introduced to the surface in the form of triorganosilylation of silanol groups remaining on the surface of the first hydrophobic spherical silica fine particles.

In the general formulas (III) and (IV), R ² is preferably a monovalent hydrocarbon group having 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms. The monovalent hydrocarbon group represented by R ² is, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group or a butyl group, preferably a methyl group, an ethyl group or a propyl group, particularly preferably , Methyl group or ethyl group. Further, some or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom, preferably a fluorine atom.

  Examples of the hydrolyzable group represented by X include a chlorine atom, an alkoxy group, an amino group, and an acyloxy group, preferably an alkoxy group or an amino group, and particularly preferably an alkoxy group.

  Examples of the silazane compound represented by the general formula (III) include hexamethyldisilazane and hexaethyldisilazane, and preferably hexamethyldisilazane. Examples of the monofunctional silane compound represented by the general formula (IV) include monosilanol compounds such as trimethylsilanol and triethylsilanol; monochlorosilanes such as trimethylchlorosilane and triethylchlorosilane; monoalkoxy such as trimethylmethoxysilane and trimethylethoxysilane. Silane; monoaminosilane such as trimethylsilyldimethylamine and trimethylsilyldiethylamine; monoacyloxysilane such as trimethylacetoxysilane, preferably trimethylsilanol, trimethylmethoxysilane or trimethylsilyldiethylamine, particularly preferably trimethylsilanol or trimethylmethoxysilane It is done.

  The amount of the silazane compound or / and functional silane compound used is 0.1 to 0.5 mol, preferably 0.2 to 0.4 mol, particularly preferably 0.25 to 0.35 mol, per 1 mol of Si atoms in the used hydrophilic spherical silica fine particles. is there. When the amount used is less than 0.1 mol, the dispersibility of the resulting hydrophobic silica fine particles is deteriorated, so that the effect of imparting fluidity to metal silicon does not appear. When the amount used is more than 0.5 mol, it is economically disadvantageous.

  The hydrophobic spherical silica fine particles are obtained as a powder by a conventional method such as atmospheric drying or reduced pressure drying.

<Metal silicon composition>
The metal silicon powder of the present invention is obtained by adding the hydrophobic spherical silica fine particles to the metal silicon powder as a raw material, mixing them, and attaching the silica fine particles to the surface of the metal silicon powder by physical adsorption. . The addition amount of the hydrophobic spherical silica fine particles to the metal silicon powder is preferably 0.01 to 5.0% by mass, more preferably 0.1 to 4.0% by mass, particularly 0.5 to 0.5% by mass of the metal silicon powder. 3.0% by mass. If the amount added is less than 0.01% by mass, the fluidity of the metal silicon powder may not change, which is not preferable. Moreover, when this addition amount exceeds 5.0 mass%, it may not be preferable in terms of cost. The metal silicon powder is usually a powder composed of the metal silicon powder and the hydrophobic spherical silica fine particles, but may optionally contain an additive such as a coupling agent.

  In order to adhere the hydrophobic silica fine particles to the metal silicon powder, a known mixing method may be used. By using a Henschel mixer, a V-type blender, a ribbon blender, a raking machine, a kneader mixer, a butterfly mixer, or a normal propeller stirrer What is necessary is just to mix the predetermined amount of each component uniformly using a mixer. Then, it can be easily attached to the metal silicon powder.

<Resin composition using metal silicon powder>
An organic resin is used as the resin combined with the metal silicon powder of the present invention, and the organic resin is not particularly limited, but is an epoxy resin, silicone resin, phenol resin, melamine resin, urea resin, unsaturated polyester, fluororesin; polyimide , Polyamides such as polyamideimide and polyetherimide; polyesters such as polybutylene terephthalate and polyethylene terephthalate; polyphenylene sulfide, wholly aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide modified resin, ABS resin, and AAS (acrylonitrile)・ Acrylic rubber, styrene) resin, AES (acrylonitrile, ethylene, propylene, diene rubber, styrene) resin, etc., thermosetting resin, thermoplastic resin, or various engineers Ring plastic is exemplified. The polymer matrix constituents as described above can be selected as the organic resin, and 0.01 to 600 parts by mass, preferably 0.01 to 500 parts by mass of the metal silicon powder of the present invention with respect to 100 parts by mass of the organic resin. Parts, particularly preferably in an amount of 30 to 450 parts by weight. Thereby, the thermal conductivity of the organic resin can be improved. If the amount added to 100 parts by mass of the resin is less than 0.01 parts by mass, preferable thermal conductivity derived from metal silicon cannot be imparted, and if it is more than 600 parts by mass, the resin composition may not be molded successfully. Is not preferable.

  The resin composition using the metal silicon powder of the present invention is used in the art such as melt-mixing using equipment such as a mill, Banbury, Brabender, single- or twin-screw extruder, continuous mixer, kneader, etc. It can be prepared by techniques known in the art.

  The resin composition using the metal silicon powder of the present invention comprises a microprocessor package or automobile parts and components; articles, parts, sheets or films used in tires or bearing housings; microprocessors and integrated circuit chips; plastic balls Grid array packages, quad flat packs and other common surface mount integrated circuit packages; heat exchanger parts such as heat sinks, sheets or films; belts such as fuser rolls, but are not limited to these Absent.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The following examples do not limit the present invention.

  As the metal silicon powder used in the examples, one having a volume average particle diameter of 6.0 μm was used. This powder has a silicon content (purity) of 98.5% and an irregular shape.

[Synthesis of hydrophobic spherical silica fine particles]
<Synthesis Example 1>
Step (A1): Step of synthesizing hydrophilic spherical silica fine particles 989.5 g of methanol, 135.5 g of water, and 66.5% of 28% ammonia water in a 3 liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer g and mixed. This solution was adjusted to 35 ° C., and 436.5 g (2.87 mol) of tetramethoxysilane was added dropwise over 6 hours while stirring. Even after the completion of the dropwise addition, the suspension was further stirred for 0.5 hours for hydrolysis to obtain a suspension of hydrophilic spherical silica fine particles.

-Step (A2): Surface treatment step with trifunctional silane compound 4.4 g (0.03 mol) of methyltrimethoxysilane was added dropwise to the suspension obtained above at room temperature over 0.5 hours and stirred for 12 hours after the addition. Then, the surface of the silica fine particles was hydrophobized to obtain a dispersion of hydrophobic spherical silica fine particles.

-Concentration step Next, an ester adapter and a condenser tube were attached to a glass reactor, and the dispersion obtained in the previous step was heated to 60 to 70 ° C to distill off 1021 g of a mixture of methanol and water, thereby forming a hydrophobic sphere. A mixed solvent concentrated dispersion of silica fine particles was obtained. At this time, the content of hydrophobic spherical silica fine particles in the concentrated dispersion was 28% by mass.

-Step (A3): Surface treatment step with a functional silane compound After adding 138.4 g (0.86 mol) of hexamethyldisilazane to the concentrated dispersion obtained in the previous step at room temperature, The silica fine particles in the dispersion were trimethylsilylated by heating to 60 ° C. and reacting for 9 hours. Subsequently, the solvent in this dispersion was distilled off at 130 ° C. under reduced pressure (6650 Pa) to obtain 186 g of hydrophobic spherical silica fine particles (1).

  The hydrophilic spherical silica fine particles obtained in the step (A1) were measured according to the following measuring method 1. Further, the hydrophobic spherical silica fine particles obtained through the respective steps (A1) to (A3) were measured according to the following measuring methods 2 to 3. The obtained results are shown in Table 1.

[Measurement methods 1 to 3]
1. Particle size measurement of the hydrophilic spherical silica fine particles obtained in the step (A1) The silica fine particle suspension was added to methanol so that the silica fine particles were 0.5% by mass, and the fine particles were subjected to ultrasonic waves for 10 minutes. Was dispersed. The particle size distribution of the fine particles treated in this way is measured with a dynamic light scattering method / laser Doppler nanotrack particle size distribution measuring device (trade name: UPA-EX150, manufactured by Nikkiso Co., Ltd.), and the volume-based median diameter is measured as particles. The diameter. The median diameter is a particle diameter corresponding to 50% cumulative when the particle size distribution is expressed as a cumulative distribution.

2. Particle size measurement of hydrophobic spherical silica fine particles obtained in step (A3) and measurement of particle size distribution D90 / D10 Silica fine particles were added to methanol so as to be 0.5% by mass, and subjected to ultrasonic waves for 10 minutes, The fine particles were dispersed. The particle size distribution of the fine particles treated in this way is measured with a dynamic light scattering method / laser Doppler nanotrack particle size distribution measuring device (trade name: UPA-EX150, manufactured by Nikkiso Co., Ltd.), and the volume-based median diameter is measured as particles. The diameter. Measurement of the particle size distribution D90 / D10 is a value measured by setting D10 to be a particle size with a cumulative value of 10% from the small side and D90 to be a particle size with a cumulative value of 90% from the small side. From this, D90 / D10 was calculated.

3. Shape measurement of hydrophobic spherical silica fine particles The shape was confirmed by observation with an electron microscope (manufactured by Hitachi, trade name: S-4700 type, magnification: 100,000 times). The term “spherical” includes not only a true sphere but also a slightly distorted sphere. The shape of such particles is evaluated by the circularity when the particles are projected two-dimensionally, and the circularity is in the range of 0.8 to 1. Here, the circularity is (peripheral length of a circle equal to the particle area) / (peripheral length of particle).

<Synthesis Example 2>
In the same manner as in Synthesis Example 1, except that the amounts of methanol, water, and 28% ammonia water were changed to 1045.7 g of methanol, 112.6 g of water, and 33.2 g of 28% ammonia water in the step (A1). 188 g of silica fine particles (2) were obtained. Measurement was performed in the same manner as in Synthesis Example 1 using these hydrophobic spherical silica fine particles. The results are shown in Table 1.

<Synthesis Example 3>
・ Process (A1):
In a 3 liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer, 623.7 g of methanol, 41.4 g of water and 49.8 g of 28% aqueous ammonia were added and mixed. The solution was adjusted to 35 ° C., and 1163.7 g of tetramethoxysilane and 418.1 g of 5.4% aqueous ammonia were simultaneously added to the solution while stirring. The former was added dropwise over 6 hours and the latter over 4 hours. did. Even after the tetramethoxysilane was added dropwise, the mixture was stirred for 0.5 hours for hydrolysis to obtain a silica fine particle suspension.

・ Process (A2):
To the suspension thus obtained, 11.6 g of methyltrimethoxysilane (0.01 molar equivalent to tetramethoxysilane) was added dropwise at room temperature over 0.5 hours, and after the addition, the mixture was stirred for 12 hours, The surface of silica fine particles was treated.

  An ester adapter and a condenser tube were attached to the glass reactor, and 1440 g of methyl isobutyl ketone was added to the dispersion containing silica fine particles that had been subjected to the above surface treatment. Distilled off over time.

・ Process (A3):
To the dispersion thus obtained, 357.6 g of hexamethyldisilazane was added at room temperature, heated to 120 ° C., and reacted for 3 hours to trimethylsilylate the silica fine particles. Thereafter, the solvent was distilled off under reduced pressure to obtain 472 g of spherical hydrophobic silica fine particles (3).

  The silica fine particles (3) thus obtained were measured in the same manner as in Synthesis Example 1. The results are shown in Table 1.

<Synthesis Example 4>
Hydrophobic spherical silica fine particles (4) were obtained in the same manner as in Synthesis Example 3 except that the hydrolysis temperature of tetramethoxysilane was changed to 20 ° C. instead of 35 ° C. during the synthesis of the silica fine particles. 469 g was obtained. The same measurement as in Synthesis Example 1 was performed using this hydrophobic spherical silica fine particle (4). The results are shown in Table 1.

<Comparative Synthesis Example 1>
A 0.3 liter glass reactor equipped with a stirrer and a thermometer was charged with 100 g of deflagration silica (trade name: SOC1, manufactured by Admatechs), 1 g of pure water was added with stirring, and after sealing, further sealed at 60 ° C Stir for 10 hours. Subsequently, after cooling to room temperature, 2 g of hexamethyldisilazane was added with stirring, and after sealing, the mixture was further stirred for 24 hours. The temperature was raised to 120 ° C., and the remaining raw material and the produced ammonia were removed while ventilating nitrogen gas to obtain 100 g of hydrophobic spherical silica fine particles (5).

  The obtained silica fine particles (5) were measured in the same manner as in Synthesis Example 1. The results are shown in Table 1.

<Comparative Synthesis Example 2>
A 0.3 liter glass reactor equipped with a stirrer and a thermometer was charged with 100 g of deflagration silica (trade name: SOC1, manufactured by Admatechs), 1 g of pure water was added with stirring, and after sealing, further sealed at 60 ° C Stir for 10 hours. Next, after cooling to room temperature, 1 g of methyltrimethoxysilane was added with stirring, and after sealing, the mixture was further stirred for 24 hours. Next, 2 g of hexamethyldisilazane was added with stirring. After sealing, the mixture was further stirred for 24 hours. The temperature was raised to 120 ° C., and the remaining raw material and the produced ammonia were removed while ventilating nitrogen gas to obtain 101 g of hydrophobic spherical silica fine particles (6). The obtained silica fine particles (6) were measured in the same manner as in Synthesis Example 1. The results are shown in Table 1.

<Examples 1-5, Comparative Examples 1-5>
Hydrophobic spherical silica fine particles (1) to (6) obtained in the above synthesis examples or comparative synthesis examples are added to metal silicon powder (volume average particle diameter: 5.0 μm, manufactured by Kinsei Matec Co., Ltd.) in the amounts shown in Table 2. The mixture was stirred and mixed for 1 minute by a sample mill. The obtained metallic silicon powder was measured for basic fluidity energy, which is an index of powder fluidity. Further, 50 g of each metal silicon powder sample was weighed and supplied to a 200 mesh sieve, and then the mass ratio of the sample that passed through the sieve when held for 1 minute was measured. The results are shown in Table 2.
Moreover, the electron micrograph of the metal silicon powder which adhered the spherical hydrophobic silica fine particles of Examples 2 and 4 to the powder surface is shown in FIGS. 1 and 2, respectively, and the spherical hydrophobic silica fine particles of Comparative Example 5 are metallic silicon. an electron micrograph of the untreated metal silicon powder is not added to the powder shown in Figure 3.

  The powder fluidity was measured using a powder fluidity analyzer FT-4 (manufactured by Sysmex Corporation). The measurement principle of this apparatus will be described. A cylindrical container placed vertically is filled with powder, and while rotating two rotating blades (blades) provided at the tip of a vertical shaft rod in the powder, a certain distance (from height H1) Down to H2. The force received from the powder at this time is measured separately for the torque component and the load component, so that each work (energy) associated with the blade descending from H1 to H2 is obtained, and then the total energy amount of both Ask for. The smaller the total energy measured in this way, the better the fluidity of the powder, so it is used as an index of powder fluidity. A stability test was also conducted with this apparatus.

··conditions:
Container: A glass cylindrical container having a volume of 160 ml (inner diameter: 50 mm, length: 79 mm) was used.

  Blades: Two blades are mounted horizontally facing the tip of a stainless steel shaft rod inserted vertically into the center of the cylindrical container. A blade with a diameter of 48 mm is used. The length from H1 to H2 is 69 mm.

.. Fluidity test: As described above, the powder flow characteristics when the powder filled in the measurement container is allowed to flow from a static state are observed. Measure the total energy amount 7 times continuously with the blade tip rotation speed as 100mm / sec. Table 7 shows the total energy amount for the seventh time (referred to as basic fluidity energy because it is the most stable state). The smaller the value, the higher the fluidity.
・ ・ Stability test: Following the fluidity test, measure the total energy when the blade rotation speed is changed from 100 mm / sec → 70 mm / sec → 40 mm / sec → 10 mm / sec. It can be said that the FRI fluctuation index (Flow Rate Index) at that time is closer to 1, and the flow rate is more stable. FRI fluctuation index = (10 mm / s data) / (100 mm / s data).

<Note>
1) Particle size of hydrophilic spherical silica fine particles of dispersion obtained in step (A1) 2) Particle size of hydrophobic silica fine particles finally obtained

<Example 6>
Preparation of Thermal Conductive Sheet 100 g of metal silicon powder of Example 4, 11.3 g of epoxy resin (trade name “YSLV-80XY”, manufactured by Toto Kasei Co., Ltd.), cresol novolac resin (trade name “YDCN-701, manufactured by Toto Kasei Co., Ltd.) “] 11.3 g and a curing accelerator (boron trifluoride monoethylamine) 0.26 g were put into a small pulverizer and mixed to prepare a resin composition.
This resin composition was formed into a sheet by press molding (180 ° C. × 10 minutes) using a mold to produce a heat conductive sheet (thickness 0.2 mm).

(Evaluation)
About the said heat conductive sheet, the heat conductivity and the dielectric breakdown voltage were measured. In addition, thermal conductivity calculates | requires a thermal diffusivity by the product name "ai-phase mobile" by an eye phase company, Furthermore, per unit volume of a heat conductive sheet by the measurement using a differential scanning calorimeter (DSC). The heat capacity was measured and calculated by multiplying the previous thermal diffusivity.
The dielectric breakdown voltage was measured at a pressure increase rate of 1 kV / min in normal temperature insulating oil (Type 1 No. 2 insulating oil specified in JIS C 2320). Furthermore, the brittleness of each thermal conductive sheet is judged by touch, and “○” indicates that the handling is good and does not cause any trouble during molding. What was felt as “△” was judged as “△”, and what was fragile and required careful handling at the time of molding was judged as “x”.
The results are shown in Table 3.

<Comparative Example 6>
A heat conductive sheet (thickness 0.2 mm) was prepared and evaluated in the same manner as in Example 6 except that 100 g of the metal silicon powder of Example 6 was changed to 100 g of untreated metal silicon powder. The results are shown in Table 3.

Claims (6)

(A1) a step of obtaining hydrophilic spherical silica fine particles substantially consisting of SiO ₂ units by hydrolyzing and condensing a tetrafunctional silane compound, a partially hydrolyzed condensation product thereof, or a mixture thereof;
(A2) R ¹ SiO _3/2 unit (wherein R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms) is introduced onto the surface of the hydrophilic spherical silica fine particles. Process,
(A3) introducing a R ² ₃ SiO _1/2 unit (wherein each R ² is the same or different and is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms). According to the method , hydrophobic spherical silica fine particles (1) having a particle size in the range of 0.005 to 1.0 μm , a particle size distribution D90 / D10 value of 3 or less and an average circularity of 0.8 to 1 are produced.
The hydrophobic spherical silica fine particles (1) are added to the metal silicon powder in an amount of 0.01 to 5.0% by mass with respect to the mass of the metal silicon powder, mixed, and the hydrophobic spherical silica fine particles (1). Is made to adhere to the surface of the metal silicon powder. A method for producing the hydrophobic spherical silica fine particles (1) comprises:
(A1) General formula (I):
Si (OR ³ ) ₄ (I)
(Wherein each R ³ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms), a tetrafunctional silane compound, a partial hydrolysis product thereof, or a mixture thereof, In the presence of a substance, a mixed solvent dispersion of hydrophilic spherical silica fine particles substantially consisting of SiO ₂ units is obtained by hydrolysis and condensation in a mixed liquid of a hydrophilic organic solvent and water,
(A2) In the mixed solvent dispersion of the obtained hydrophilic spherical silica fine particles, the general formula (II):
R ¹ Si (OR ⁴ ) ₃ (II)
Wherein R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and each R ⁴ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms. The surface of the hydrophilic spherical silica fine particles is treated with R ¹ SiO _{3 /} by adding a trifunctional silane compound, a partial hydrolysis product thereof, or a mixture thereof to treat the surface of the hydrophilic spherical silica fine particles. ₂ units (R ¹ is as described above) were introduced to obtain a mixed solvent dispersion of the first hydrophobic spherical silica fine particles,
(A3) In the mixed solvent dispersion of the obtained first hydrophobic spherical silica fine particles, the general formula (III):
R ² ₃ SiNHSiR ² ₃ (III)
(In the formula, each R ² is the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms)
Silazane compounds represented by general formula (IV):
R ² ₃ SiX (IV)
(Wherein R ² is as defined in the general formula (III), X is an OH group or a hydrolyzable group), or a mixture thereof, The surface of the first hydrophobic spherical silica fine particles is treated thereby, and R ² ₃ SiO _1/2 units (R ² is defined by the general formula (III) are formed on the surface of the first hydrophobic spherical silica fine particles. The method for producing a powder according to claim 1, wherein the second hydrophobic silica fine particles are obtained by introducing The method for producing a powder according to claim 2, wherein the mixed solvent dispersion of the first hydrophobic spherical silica fine particles obtained in the step (A2) is concentrated before being subjected to the step (A3). Preparation of claim 1 to obtain a powder by the method according to any one of 3, the obtained powder, the resin composition is characterized by adding from 0.01 to 600 parts by weight per 100 parts by weight resin Way . The resin is an epoxy resin, silicone resin, phenol resin, melamine resin, urea resin, unsaturated polyester, fluororesin; polyamide such as polyimide, polyamideimide, or polyetherimide; polyester such as polybutylene terephthalate or polyethylene terephthalate; polyphenylene sulfide , Fully aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide modified resin, ABS resin, AAS (acrylonitrile / acrylic rubber / styrene) resin, AES (acrylonitrile / ethylene / propylene / diene rubber / styrene) resin The manufacturing method of the resin composition of Claim 4 which is 1 type or more to be used . A method for producing a heat and heat conductive sheet , comprising: obtaining a resin composition by the method according to claim 4 or 5; and molding the obtained resin composition.