Spherical alumina particles, a method for producing the same, a method for surface treatment of a raw material for spherical alumina particles, and a resin composite composition containing the spherical alumina particles, and a resin composite composition

Abstract

To provide a spherical alumina particle with high affinity with resin, and few impurity ions remaining on the surface and a method for producing the same.SOLUTION: The present invention provides a spherical alumina particle with a sodium ion concentration of 5 ppm or less, a potassium ion concentration of 10 ppm or less, and a surface OH group content of 8 / nm2 or more and 100 / nm2 or less and a method for producing the same.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to spherical alumina particles, spherical alumina particles typically used to fill heat dissipation members, and methods for producing the same. The invention also relates to a surface treatment method for spherical alumina particle raw materials, and to resin composite compositions containing the spherical alumina particles, as well as to resin composite compositions. [Background technology]

[0002] In recent years, the increased functionality and speed of electronic devices such as mobile phones have led to a significant increase in the amount of heat generated by electronic components within these devices. Efficiently dissipating this heat to the outside is a crucial challenge for the proper operation of electronic devices. Thermal sheets and thermal adhesives are widely used for this purpose. These are applied or coated between the heat-generating element and the heat-sinking fin, eliminating the gap between them and allowing for efficient heat dissipation. Furthermore, semiconductors within electronic components also generate significant heat due to similar increased functionality and speed, making it necessary to provide thermal dissipation properties to the encapsulating materials protecting the semiconductors.

[0003] Generally, heat dissipation sheets, heat dissipation adhesives, and semiconductor encapsulants are composed of a thermally conductive inorganic filler and a resin. The thermally conductive inorganic filler is typically an inexpensive material such as aluminum hydroxide or aluminum oxide (hereinafter referred to as alumina), or, for its higher thermal conductivity, materials such as silicon carbide, boron nitride, or aluminum nitride. As for the resin, silicone resin is commonly used for heat dissipation sheets and adhesives, while epoxy resin is generally used for semiconductor encapsulants.

[0004] Many studies have been conducted on methods to improve the thermal conductivity of these components by increasing the amount of filler added to the resin.

[0005] One method to increase the amount of filler used is to make the filler itself rounded or spherical. This method allows for a higher filler capacity compared to using irregularly shaped fillers, and it is being widely studied.

[0006] Alumina is a widely considered filler among rounded and spherical fillers. Alumina is chemically stable, and its shape can be easily changed from amorphous to rounded or spherical using methods such as flame melting, making it a popular choice for spherical fillers used in heat dissipation components. Flame melting and VMC (Vapor Mould Coking) are particularly common methods for producing spherical alumina.

[0007] Spherical alumina produced by flame melting loses its surface hydroxyl groups when heated. This reduces the reaction sites with silane coupling agents, preventing the formation of chemical bonds with the resin. As a result, the wettability with the resin being filled deteriorates, the dispersibility of the filler worsens, and aggregates of the filler form, negatively affecting the fluidity, viscosity, and thermal conductivity of the filler-resin mixture.

[0008] Patent Document 1 proposes a method for improving the wettability of spherical alumina particles with an average particle size of 50 μm or less by treating and washing them with hot water at 80°C or higher or an alkaline aqueous solution such as sodium hydroxide at 70°C or higher. However, washing with a strongly alkaline solution such as sodium hydroxide or potassium hydroxide leaves a large amount of cations such as sodium ions and potassium ions on the surface of the spherical alumina particles, which can inhibit curing reactions such as polymerization and condensation reactions of the resin being filled, and can also lead to a decrease in the insulating properties of the resin composition produced by kneading with the resin.

[0009] Patent Document 2 proposes a method in which spheroidized alumina particles are rapidly cooled by supplying water to a molten spheroidization furnace, and surface hydroxyl groups are imparted depending on the amount of water supplied. However, rapidly cooling the spheroidized particles with water causes the particle surface to solidify while the interior remains at a high temperature, resulting in the problem that the spheroidized particles become brittle. Broken particles cause an increase in the viscosity of the resin composition created by kneading with the resin. [Prior art documents]

Patent Document

[0010]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0011] An object of the present invention is to provide spherical alumina particles having a high affinity with a resin and having few impurity ions remaining on the surface, and a method for producing the same. Further, an object of the present invention is to provide a surface treatment method for a raw material of spherical alumina particles, a resin composite composition containing the spherical alumina particles, and a resin composite composition.

Means for Solving the Problems

[0012] The present invention has been made as a result of intensive studies to solve the above-described problems, and the gist thereof is as follows as described in the claims. [1] Spherical alumina particles characterized in that the sodium ion concentration is 5 ppm or less, the potassium ion concentration is 10 ppm or less, and the amount of surface OH groups is 8 per nm to 100 per nm 2 or less. [2] The amount of surface OH groups is 21 per nm 2 or more, and the spherical alumina particles according to [1]. [3] The circularity of the spherical alumina particles is 0.8 or more, and the spherical alumina particles according to [1]. [[ID=5)4]][4] The particle size of the spherical alumina particles is 0.5 μm or more and 160 μm or less, and the spherical alumina particles according to [1]. <00000)92>[5] The spherical alumina particles according to [1], having an α - conversion rate of 1% or more. [6] The spherical alumina particles according to [1], which are produced by a flame melting method or a VMC method.

[0013] [7] A method for producing spherical alumina particles, characterized in that spherical alumina particles according to [1] are obtained by bringing an alkali - ion water having a total concentration of sodium ions and potassium ions of 0.04 mol / L or less into contact with a raw material of spherical alumina particles. [8] The method for producing spherical alumina particles according to [7], wherein the alkali - ion water contains potassium hydroxide, magnesium hydroxide, beryllium hydroxide, strontium hydroxide, and barium hydroxide. <了` [9] A method for surface - treating a raw material of spherical alumina particles, characterized in that spherical alumina particles according to [1] are obtained by bringing an alkali - ion water having a total concentration of sodium ions and potassium ions of 0.04 mol / L or less into contact with a raw material of spherical alumina particles.

[10] A resin composite composition, characterized by containing the spherical alumina particles according to any one of [1] to [6] in a resin.

[11] A resin composite, characterized by being formed by curing the resin composite composition according to

[10] . [Effect of the Invention]

[0014] [[ID=4Q]]The spherical alumina particles of the present invention are treated with alkali - ion water, so that the content of residual sodium ions and potassium ions on the surface is small, and the amount of surface hydroxyl groups is larger than that of other spherical alumina particles, and it is expected that the reactivity with a silane coupling agent is also improved. Therefore, the affinity with a resin is improved, and high filling in various resins can be achieved. [Modes for carrying out the invention]

[0015] The present invention will be described in detail below. One embodiment of the present invention provides spherical alumina particles, which can be obtained by treatment with alkaline ionized water, having a sodium ion concentration of 5 ppm or less, a potassium ion concentration of 10 ppm or less, and a surface OH group count of 8 / nm. 2 More than 100 pieces / nm 2 The spherical alumina particles are characterized by the following:

[0016] (Sodium ions must be 5 ppm or less, and potassium ions 10 ppm or less). In one aspect of the present invention, spherical alumina particles are typically used as a filler in a silicone resin heat dissipation sheet. The siloxane bonds, which form the basic framework of silicone resin, are ionic bonds, and there is a risk that these bonds may be broken by the influence of alkali metal cations. If the siloxane bonds are broken, the material cannot be molded as a heat dissipation component. Therefore, it is preferable to have fewer alkali metal cations, as this reduces the impact on the silicone resin.

[0017] In another aspect of the present invention, spherical alumina particles are typically used as fillers in epoxy resins for semiconductor encapsulants. If a large amount of alkali metal cations are present on the filler surface, they react with moisture in the resin and air to release hydroxide ions. These hydroxide ions react with epoxy groups present in the epoxy resin, inhibiting the polymerization reaction between the resins and causing curing defects. Furthermore, if sodium or potassium ions are present in the resin composition created by kneading with epoxy groups, the dielectric strength is impaired. From these points of view, it is desirable to have a small amount of alkali metal cations. Therefore, in one aspect of the present invention, the spherical alumina particles have a sodium ion concentration of 5 ppm or less and a potassium ion concentration of 10 ppm or less.

[0018] (Measurement of the amount of ionic impurities adhering to the surface) The amount of ionic impurities adhering to the surface can be measured using an ion chromatograph. Add 4 g of the sample and 40 ml of distilled water to a centrifuge tube, cover it, and shake well to mix. After mixing, separate it into the sample and the sample solution using a centrifuge. Take out a portion of the sample solution and analyze sodium ions and potassium ions using an ion chromatograph. The ion chromatograph used was the one manufactured by Tosoh Corporation for measurement.

[0019] (The amount of surface OH groups is 8 per nm 2 or more and 100 per nm 2 or less) In the spherical alumina particles as manufactured by the flame melting method, the OH groups present on the surface have become water molecules and disappeared due to heat treatment. Therefore, they cannot react with the silanol groups of the silane coupling agent that improves the compatibility and adhesion with the resin. Therefore, the amount of surface OH groups is 8 per nm 2 or more. Also, the greater the amount of surface OH groups, the higher the reactivity with the silanol groups. Therefore, the amount of surface OH groups is preferably 21 per nm 2 or more.

[0020] On the other hand, if the amount of OH groups on the surface of the spherical alumina particles is too large, moisture in the air is likely to adhere. When the amount of moisture increases, when reacting with the silane coupling agent, the silanol groups of the silane coupling agent react with the adhered moisture, and as a result, the spherical alumina particles and the silane coupling agent do not react, and the effect of improving the adhesion and compatibility with the resin may not be obtained. Also, if there is a lot of attached water on the surface of the spherical alumina particles, the resin composition will contain a lot of moisture and the breakdown voltage resistance will decrease. Therefore, the amount of surface OH groups is preferably 100 per nm 2 or less. From the perspective of suppressing attached water, the amount of surface OH groups is 100 per nm 2 or less, preferably 85 per nm 2 or less.

[0021] (Circularity) In one aspect of the present invention, spherical alumina particles are generally mixed with resin and used as fillers for various heat dissipation components. Specifically, the resin composition created by mixing with resin is molded into various heat dissipation components. If the shape of the filled material is round, the viscosity of the resin composition will be lower.

[0022] This suggests that if the filler has a rounded shape, when it flows in contact with other particles, the particles will efficiently absorb force like rolling bearings, reducing friction between particles. From this viewpoint, in one aspect of the present invention, spherical alumina particles may have a circularity of 0.80 or higher. If the circularity is less than 0.80, the viscosity will be high, and the fluidity may not be sufficient. From the viewpoint of improving fluidity, a higher circularity is preferable, and it may be 0.85 or higher, or even 0.90 or higher. On the other hand, since it may be difficult to achieve a circularity of 1.0, i.e., a perfect circle, the upper limit of the circularity may be 0.99 or lower, or 0.97 or lower.

[0023] (Measurement of circularity) Circularity can be measured using an electron microscope or optical microscope and an image analysis device, such as the FPIA manufactured by Sysmex Corporation. These devices are used to measure the circularity of particles (perimeter of the area equivalent to a circle / perimeter of the projected image of the particle). The circularity is measured for 100 or more particles, and the average value is taken as the circularity of the powder.

[0024] (Average particle size) In one aspect of the present invention, the average particle size (D50) of the spherical alumina particles may be 0.5 to 160 μm. If the average particle size is less than 0.5 μm, the particle cohesiveness increases, and the fluidity of the resin composition is significantly reduced when used as a filler, which is undesirable. If the average particle size exceeds 160 μm, voids between particles tend to remain, making it difficult to improve the particle packing when used as a filler, which is also undesirable. An average particle size of 1 to 150 μm is a more preferable range.

[0025] The average particle size (D50) was determined by the median diameter D50 at which the cumulative volume reaches 50% in the volume-based particle size distribution, measured using the laser diffraction-scattering particle size distribution method. The laser diffraction-scattering particle size distribution method involves irradiating a dispersion of spherical alumina particles with laser light and determining the particle size distribution from the intensity distribution pattern of the diffracted and scattered light emitted from the dispersion. In this invention, the laser diffraction-scattering particle size distribution analyzer "Mastersizer3000" (manufactured by Malvern) was used. The average particle size of the raw material for the spherical alumina particles can also be determined similarly.

[0026] (gelatinization rate) It is known that alumina exhibits different thermal conductivity depending on its crystal system, with α-alumina being the crystal with the highest thermal conductivity. Therefore, by using alumina particles containing a large amount of α-alumina as a filler to be mixed with resin, the thermal conductivity of the resin composition can be improved. In this respect, the higher the α-conversion rate of the spherical alumina particles in bulk (the proportion of α-alumina among the crystals contained in the alumina particles), the higher the thermal conductivity of the spherical alumina particles, which is preferable. From this viewpoint, the α-conversion rate is preferably 1% or more, more preferably 5% or more, and more preferably 10% or more. The upper limit of the α-conversion rate is not particularly limited, and it may be set to 100%, but this may result in excessive manufacturing costs, so the upper limit may be less than 90%, 85% or less, or 75% or less.

[0027] Alpha-alumina is obtained by treating the starting material at high temperatures to promote crystal growth; for example, it is generally obtained by heating alumina at high temperatures. Heating methods include firing in a furnace or heating with high-temperature hot water.

[0028] <Measurement of Alpha-Coating Rate> The alpha-adsorption rate is measured using a powder X-ray diffractometer. The integrated area of ​​the obtained diffraction peaks is determined, and the ratio of the diffraction peak area originating from α-alumina to the total area is analyzed using the Rietveld method.

[0029] (Raw material for spherical alumina particles) The raw materials for spherical alumina particles (sometimes referred to as "spherical alumina particle raw materials") can be manufactured from alumina powder, aluminum hydroxide powder, or metallic aluminum (hereinafter sometimes collectively referred to as "alumina raw materials"). In other words, "spherical alumina particle raw materials" can be manufactured from "alumina raw materials," and "spherical alumina particle raw materials" are the raw materials for "spherical alumina particles," which is one aspect of the present invention; these are clearly distinguishable. Typically, as will be detailed later, "spherical alumina particle raw materials" can be manufactured by spheroidizing "alumina raw materials" by flame spraying or the like, and "spherical alumina particles," which is one aspect of the present invention, can be obtained by treating the resulting "spheroidized alumina particle raw materials" with alkaline ionized water.

[0030] (Method for producing spherical alumina particle raw materials) Spherical alumina particle raw materials can be produced by spheroidizing the alumina raw material using a flame melting method or a VMC method.

[0031] The flame melting method is a known thermal spraying method in which alumina raw material is sprayed into a flame to oxidize and / or sphericalize the alumina particles. At this time, the average sphericity can be adjusted by the amount of material injected into the flame per hour and the type of fuel gas used. Furthermore, the particle size of the spherical alumina after thermal spraying can be adjusted by adjusting the particle size of the alumina raw material used. In addition, the alpha-gelatinization rate can be reduced by rapidly cooling the spherical particles immediately after melting and solidifying with a refrigerant such as air or water. There are no particular restrictions on the refrigerant, but from the viewpoint of not reducing the purity of the spherical particles, distilled water or ion-exchanged water that does not contain air or impurities such as sodium ions or chloride ions is desirable.

[0032] The VMC method is a process in which a chemical flame is formed by a burner in an oxygen-containing atmosphere, and a quantity of metal powder is added to this flame to form a dust cloud, causing deflagration and obtaining spherical oxide particles. The VMC method (deflagration method) can be used to react metal materials such as aluminum with oxygen to obtain spherical metal oxides such as alumina.

[0033] The spherical alumina particles can be separated into coarse and fine particles using a cyclone or the like, as needed. The spherical alumina particle raw material obtained in this way can be classified into particles of the desired average particle size using a sieve with a predetermined mesh size or using an air classifier.

[0034] (Method for producing spherical alumina particles <Alkaline ionized water treatment>) Spherical alumina particles according to one embodiment of the present invention can be produced by surface modification of classified spherical alumina particle raw materials. The surface modification method can be performed using alkaline ionized water. Alkaline ionized water is placed in a container, heated and stirred, and the spherical alumina particle raw materials are added and treated. The heating temperature is preferably 70°C or higher from the viewpoint of promoting the reaction between the spherical alumina particle raw materials and the alkaline solution. The heating time is preferably 1 hour or more, more preferably 8 hours or more, and even more preferably 72 hours or more. After heating, the spherical alumina particle raw materials are filtered through a filter such as a nonwoven fabric and washed with a cleaning solution for the filtered residue. Washing is performed until the pH of the cleaning solution is about 7 to 8. From the viewpoint of preventing ionic components contained in the cleaning solution from remaining on the surface of the filter residue, ion-exchanged water, distilled water, or ultrapure water are preferred as the cleaning solution. By heating and drying the washed filter residue, spherical alumina particles treated with alkaline ionized water can be obtained. From the viewpoint of evaporating the water contained in the spherical alumina particles, the drying conditions are preferably 100°C or higher and the heating time is preferably 1 hour or more.

[0035] (Alkaline ionized water) Alkaline ionized water can be obtained by recovering the aqueous solution on the cathode side when an aqueous solution of potassium chloride, magnesium chloride, calcium chloride, barium chloride, beryllium chloride, strontium chloride, etc. is electrolyzed. The alkaline ionized water obtained by electrolyzing these aqueous solutions contains potassium hydroxide, magnesium hydroxide, beryllium hydroxide, strontium hydroxide, and barium hydroxide. Commercially available or known alkaline ionized water may be used, for example, First manufactured by Daiichi Sangyo Co., Ltd., e-Wash manufactured by E-Plan Co., Ltd., Alkaline Ionized Water S manufactured by Suzuki Oil & Fat Industry Co., Ltd., Water Gekiochi-kun manufactured by Rec Co., Ltd., and Strong Alkaline Ionized Electrolyzed Water manufactured by JSK Co., Ltd. can be used. From the viewpoint of promoting the reaction on the alumina surface, the concentration of the electrolyte contained in the alkaline ionized water used (concentration of potassium hydroxide, calcium hydroxide, etc.) is preferably 0.001 to 1 mol / L when converted to the concentration of cations (i.e., for example, when potassium hydroxide and / or sodium hydroxide are used as alkaline ionized water, the total of sodium ion concentration and potassium ion concentration) is preferably 0.001 to 1 mol / L. Furthermore, minimizing the amount of cations remaining on the surface is preferable from the viewpoint of preventing the resin from curing or its structure from being destroyed when mixed with the resin. Therefore, the upper limit of the electrolyte concentration is preferably 0.5 mol / L or less, more preferably 0.1 mol / L or less, even more preferably 0.05 mol / L or less, and even more preferably 0.04 mol / L or less.

[0036] (Surface treatment method for spherical alumina particle raw materials) In addition, one embodiment of the present invention also provides a surface treatment method for spherical alumina particle raw materials, in which spherical alumina particles are obtained by contacting the spherical alumina particle raw materials with alkaline ionized water.

[0037] (Applications of spherical alumina particles) According to one aspect of the present invention, a composite composition of spherical alumina particles and resin obtained as the final product, and a resin composite obtained by curing the resin composite composition, can be manufactured. The composition of the resin composite composition and other details will be described in detail below.

[0038] A slurry composition containing spherical alumina particles and resin can be used to obtain resin composite compositions such as semiconductor encapsulants (especially solid encapsulants) and interlayer insulating films. Furthermore, by curing these resin composite compositions, resin composites such as encapsulants (cured bodies) and semiconductor package substrates can be obtained.

[0039] When manufacturing the aforementioned resin composite composition, for example, in addition to spherical alumina particles and resin, a curing agent, curing accelerator, flame retardant, silane coupling agent, etc., are added as needed and compounded by known methods such as kneading. Then, it is molded into pellets, films, etc., according to the application.

[0040] Furthermore, when manufacturing the resin composite composition, other inorganic fillers may be added in addition to spherical alumina particles and resin. Examples of such inorganic fillers include amorphous spherical silica particles, crystalline spherical silica particles, titania particles, magnesia particles, aluminum nitride particles, boron nitride particles, barium titanate particles, and calcium titanate particles. The blending ratio of the inorganic fillers can be appropriately adjusted depending on the application of the resin composite composition.

[0041] Furthermore, when curing the resin composite composition to produce a resin composite, for example, the resin composite composition is heated and melted, processed into a shape according to the application, and then completely cured by applying a higher heat than that used during melting. In this case, known methods such as the transfer molding method can be used.

[0042] For example, when manufacturing semiconductor-related materials such as packaging substrates and interlayer insulating films, known resins can be used as the resin in the resin composite composition, but epoxy resins are preferred. The epoxy resin is not particularly limited, but for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, naphthalene type epoxy resin, phenoxy type epoxy resin, etc., can be used. One of these can be used alone, or two or more with different molecular weights can be used in combination. Among these, epoxy resins having two or more epoxy groups in one molecule are preferred from the viewpoint of curability, heat resistance, etc. Specifically, examples include biphenyl-type epoxy resins, phenol novolac-type epoxy resins, orthocresol novolac-type epoxy resins, epoxidized novolac resins of phenols and aldehydes, glycidyl ethers such as bisphenol A, bisphenol F, and bisphenol S, glycidyl ester epoxy resins obtained by the reaction of polybasic acids such as phthalic acid and dimer acid with epochlorohydrin, linear aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, alkyl-modified polyfunctional epoxy resins, β-naphthol novolac-type epoxy resins, 1,6-dihydroxynaphthalene-type epoxy resins, 2,7-dihydroxynaphthalene-type epoxy resins, bishydroxybiphenyl-type epoxy resins, and epoxy resins into which halogens such as bromine have been introduced to impart flame retardancy. Among these epoxy resins having two or more epoxy groups in one molecule, bisphenol A-type epoxy resins are particularly preferred.

[0043] Furthermore, resins other than epoxy resins can be used in applications other than composite materials for semiconductor encapsulants, such as prepregs for printed circuit boards and various engineering plastics. Specifically, in addition to epoxy resins, other resins include silicone resins, phenolic resins, melamine resins, urea resins, unsaturated polyesters, fluororesins, polyimides, polyamide-imides, polyetherimides and other polyamides; polyesters such as polybutylene terephthalate and polyethylene terephthalate; polyphenylene sulfide, aromatic polyesters, polysulfones, liquid crystal polymers, polyethersulfones, polycarbonates, maleimide-modified resins, ABS resins, AAS (acrylonitrile-acrylic rubber-styrene) resins, and AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resins.

[0044] As a curing agent used in a resin composite composition, any known curing agent may be used to cure the resin, but for example, a phenolic curing agent can be used. As a phenolic curing agent, phenol novolac resins, alkylphenol novolac resins, polyvinylphenols, etc., can be used individually or in combination of two or more.

[0045] The amount of phenol curing agent blended is preferably such that its equivalent ratio to the epoxy resin (phenolic hydroxyl group equivalent / epoxy group equivalent) is 0.1 or more and less than 1.0. This eliminates the residue of unreacted phenol curing agent and improves moisture absorption and heat resistance.

[0046] The amount of spherical alumina particles added to the resin composite composition of the present invention is preferably high from the viewpoint of heat resistance and thermal expansion coefficient, but is usually appropriate to be 70% by mass or more and 95% by mass or less, preferably 80% by mass or more and 95% by mass or less, and more preferably 85% by mass or more and 95% by mass or less. This is because if the amount of spherical alumina particles is too low, it is difficult to obtain effects such as improving the strength of the sealing material and suppressing thermal expansion, and conversely, if it is too high, segregation due to aggregation of spherical alumina particles is likely to occur in the composite material regardless of the surface treatment of the spherical alumina particles, and the viscosity of the composite material becomes too high, making it difficult to use as a sealing material.

[0047] In addition to resins, known additives such as silane coupling agents, curing agents, colorants, and curing retarders can also be used.

[0048] Furthermore, while any known coupling agent may be used as the silane coupling agent, one having an epoxy functional group is preferred.

[0049] A slurry composition containing spherical alumina particles and resin can be used to obtain heat dissipation sheets, heat dissipation greases, and the like.

[0050] In obtaining the aforementioned heat dissipation sheet, spherical alumina particles and resin are mixed with appropriate additives and compounded using known methods such as kneading. The resulting composite is then molded into a sheet using known methods.

[0051] For example, when manufacturing a heat dissipation sheet, known resins can be used as the resin in the resin composite composition. Specifically, examples include silicone resin, phenolic resin, melamine resin, urea resin, unsaturated polyester, fluororesin, polyimide, polyamide-imide, polyetherimide and other polyamides; polyesters such as polybutylene terephthalate and polyethylene terephthalate; polyphenylene sulfide, aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide-modified resin, ABS resin, AAS (acrylonitrile-acrylic rubber-styrene) resin, and AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin. Among these, silicone resin is preferred. The silicone resin is not particularly limited, but for example, peroxide-curing type, addition-curing type, condensation-curing type, ultraviolet-curing type, etc., can be used.

[0052] In addition to resins, known additives such as silane coupling agents, curing agents, colorants, and curing retarders can also be used.

[0053] In obtaining the aforementioned heat dissipation grease, spherical alumina particles and resin are combined with appropriate additives and compounded by known methods such as kneading. Here, the resin used in the heat dissipation grease is also called the base oil.

[0054] For example, when manufacturing heat dissipation grease, known resins can be used as resins in the resin composite composition, but specifically include silicone resins, phenolic resins, melamine resins, urea resins, unsaturated polyesters, fluororesins, polyimides, polyamideimides, polyetherimides and other polyamides; polyesters such as polybutylene terephthalate and polyethylene terephthalate; polyphenylene sulfide, aromatic polyesters, polysulfones, liquid crystal polymers, polyethersulfones, polycarbonates, maleimide-modified resins, ABS resins, AAS (acrylonitrile-acrylic rubber-styrene) resins, AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resins, mineral oils, synthetic hydrocarbon oils, ester oils, polyglycol oils, silicone oils, and fluorine oils.

[0055] In addition to the resin, known additives such as silane coupling agents, colorants, and thickeners can be used. Known thickeners such as calcium soap, lithium soap, aluminum soap, calcium complex, aluminum complex, lithium complex, barium complex, bentonite, urea, PTFE, sodium terephthalate, silica gel, and organic bentonite can be used.

[0056] (Mechanism of Action and Effects) In the above configuration, the spherical alumina particles of one embodiment of the present invention had an average particle size (D50) of 0.5 to 160 μm, with a surface-adhering sodium ion content of 10 ppm or less and a potassium ion content of 0.5 ppm. Because the treatment method does not use strongly alkaline solutions such as sodium hydroxide or potassium hydroxide, it is possible to provide spherical alumina particles with low amounts of sodium and potassium ions. [Examples]

[0057] The present invention will be described through the following examples and comparative examples. However, the present invention is not limited to the following examples.

[0058] (Examples 1-4) Spheroidization treatment was performed by introducing alumina particle raw material into a high-temperature flame formed by LPG and oxygen. By controlling the particle size of the introduced alumina particle raw material, spherical alumina particles of the desired particle size were produced. The obtained spherical alumina particles were separated into coarse and fine particles using a cyclone, and both coarse and fine particles were passed through a sieve of an arbitrary mesh size, and only the sieved portion was collected to obtain spherical alumina particles with the particle size and circularity shown in Table 1. The spherical alumina particles shown in Table 1 were treated in alkaline ionized water shown in Table 2, at the treatment time and temperature shown in Table 3. For Example 4, spherical alumina particle powder and alkaline ionized water were placed in a PTFE sample decomposition container and heated in a dryer at an ambient temperature of 150°C to obtain spherical alumina particle treated powder.

[0059] The obtained spherical alumina particles were measured according to the following methods: (1) average particle size, (2) residual ion content, (3) specific surface area, and (4) surface OH group content.

[0060] (1) Measurement of average particle size The average particle size of alumina particles was measured by laser diffraction / scattering. A Malvern MS3000 was used, with water as the dispersion medium. In this specification, the average particle size refers to the median diameter unless otherwise specified. The average particle size (D50) is defined as the particle size at which the cumulative frequency of the particle size distribution is 50%, measured by methods such as laser diffraction.

[0061] (2) Residual ionic components The amount of ionic impurities adhering to the surface is measured using an ion chromatograph. Typically, the measurement is performed using the following procedure. Add 4g of the sample and 40ml of distilled water to a centrifuge tube, close the lid, and shake well to mix. After mixing, separate the sample from the sample solution using a centrifuge. Take a sample of the sample solution and analyze the sodium and potassium ions using an ion chromatograph. The ion chromatograph used was manufactured by Toa Medical Electronics Co., Ltd.

[0062] (3) Specific surface area The specific surface area is measured using the BET method. Typically, the specific surface area is measured using the following procedure. Approximately 5g of the sample was weighed and vacuum-dried at 250°C for 5 minutes. Then, the sample was placed in an automatic specific surface area analyzer (Macsorb, manufactured by Mountec), and the amount of nitrogen gas adsorbed was measured at a measurement temperature of 77K using pure nitrogen and a nitrogen-helium mixed gas (mixing ratio 30% nitrogen, 70% helium) with a relative pressure P / P0 of 0.291. The BET specific surface area was then calculated using the single-point method.

[0063] (4) Surface OH group amount The amount of surface OH groups is calculated by converting the amount of water generated in the temperature range of 200°C to 550°C using the Karl Fischer coulometric titration method. Typically, the measurement is performed using the following procedure: The sample is placed in a heating furnace and heated while a stream of dry nitrogen gas is flowed through it. The amount of water generated by heating is determined by Karl Fischer titration. The amount of surface OH groups was calculated using the following formula based on the measured moisture content. Water content per unit specific surface area (μg / m²) 2 ) = Measured moisture content (wt%) / 100 × 10 6 / specific surface area (m 2 / g) Surface OH group content = Water content per unit specific surface area (μg / m²) 2 ) × 6.02 × 10 23 ×2×10 ―6 ×10 ―18 / 18

[0064] 10 6 : g / g → μg / g conversion 6.02 × 10 23 Avogadro's constant 2: Conversion from the number of water molecules to the number of OH groups. In other words, since 2 OH groups produce 1 water molecule, there are twice as many OH groups as there are water molecules. 10 ―6 :Conversion from μg to g 10 ―18 :m 2 →nm 2 conversion to 18: Molecular weight of water

[0065] As shown in Table 3, the spherical alumina treated particles of the present invention (Examples 1-4) have a higher amount of surface OH groups compared to the untreated spherical alumina particle raw material (Comparative Examples 1-3), and have a lower amount of sodium or potassium ions compared to the sodium hydroxide solution treated product (Comparative Example 6), the sodium hydroxide-containing alkaline ionized aqueous solution treated product (Comparative Example 4), or the potassium hydroxide solution treated product (Comparative Example 5). For example, comparing Example 1 with Comparative Example 1, it can be seen that the amount of surface OH groups increases due to the alkaline ionized water treatment. The same applies to Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3.

[0066] Furthermore, comparing Examples 1, 2, and 3 with Comparative Examples 4, 5, and 6, it can be seen that Examples 1, 2, and 3 have lower amounts of residual potassium and sodium ions.

[0067] [Table 1]

[0068] [Table 2]

[0069] [Table 3]

Claims

1. Sodium ion concentration is 5 ppm or less, potassium ion concentration is 10 ppm or less, and surface OH group count is 8 / nm. ２ More than 100 pieces / nm ２ The following conditions apply, and The aforementioned surface OH group amount is characterized by converting the amount of water generated in the temperature range of 200°C to 550°C by Karl Fischer coulometric titration into the amount of surface OH groups.

2. Surface OH group count: 21 / nm ２ The spherical alumina particles described in claim 1 are as described above.

3. The spherical alumina particles according to claim 1, wherein the circularity of the spherical alumina particles is 0.8 or greater.

4. The spherical alumina particles according to claim 1, wherein the particle size of the spherical alumina particles is 0.5 μm or more and 160 μm or less.

5. Spherical alumina particles according to claim 1, wherein the alpha-adsorption rate is 1% or more.

6. A method for producing spherical alumina particles, characterized by obtaining spherical alumina particles according to claim 1 by contacting a spherical alumina particle raw material with alkaline ionized water having a total sodium ion concentration and potassium ion concentration of 0.04 mol / L or less.

7. The method for producing spherical alumina particles according to claim 6, wherein the alkaline ionized water contains potassium hydroxide, magnesium hydroxide, beryllium hydroxide, strontium hydroxide, and barium hydroxide.

8. A method for surface treatment of a spherical alumina particle raw material, characterized by obtaining spherical alumina particles as described in claim 1 by contacting the spherical alumina particle raw material with alkaline ionized water having a total sodium ion concentration and potassium ion concentration of 0.04 mol / L or less.

9. The method for producing spherical alumina particles according to any one of claims 6 to 7, wherein the spherical alumina particle raw material is produced by a flame melting method or a VMC method.

10. A resin composite composition characterized by containing spherical alumina particles as described in any one of claims 1 to 5 in the resin.

11. A resin composite characterized by being obtained by curing the resin composite composition described in claim 10.

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