Thermal conductive composition

Abstract

To provide a heat conductive composition capable of obtaining a cured product having low viscosity, high thermal conductivity and moderate hardness even when a filler is highly filled into a polymer component.SOLUTION: There is provided a heat conductive composition which comprises: a polymer component (A); a surface-treated filler (B) which is surface-treated with α-butyl-ω-(2-trimethoxysilyl ethyl) polydimethylsiloxane having a weight average molecular weight of 500 to 5000 and in which the adhesion rate of the α-butyl-ω-(2-trimethoxysilyl ethyl) polydimethylsiloxane to the filler is 20.0 to 50.0 mass%; and a silicon-containing oxide-coated nitride (C) having a nitride and a silicon-containing oxide film for coating the nitride.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a heat-conducting composition. [Background technology]

[0002] Semiconductors are essential for electronic devices and automobiles. These semiconductors can malfunction and fail as their temperature rises. Therefore, various heat dissipation materials are used for thermal management. In recent years, with the increasing capabilities of semiconductors, the heat generated by these semiconductors has tended to increase, requiring materials with high thermal conductivity to quickly transfer this heat out of the system. Increasing the amount of filler is a simple and highly effective way to increase the thermal conductivity of heat dissipation materials. However, increasing the amount of filler requires techniques such as using elastomers with the lowest possible viscosity and fillers with a small specific surface area, which can be problematic due to product lineup and cost considerations. Therefore, surface treatment of fillers is employed as a method to facilitate filler filling. Silane coupling agents are a typical surface treatment agent, used to improve filling properties and other physical properties. Long-chain alkylsilanes, in particular, are relatively superior as silane coupling agents from the perspective of improving filling properties. However, even with long-chain alkylsilanes, it is becoming increasingly difficult to achieve the high filler filling required to reach the target thermal conductivity.

[0003] Furthermore, increasing the number of carbon atoms in the hydrophobic group of a long-chain alkylsilane improves its compatibility with elastomers. While alkylsilanes with up to 18 carbon atoms in the hydrophobic group are available, increasing the carbon number makes the alkoxy group less susceptible to hydrolysis, making it difficult to prepare a solution for dispersion in the filler. Additionally, polymerization and film formation between silane coupling agents can be slow or not occur at all, resulting in a large amount of unreacted silane coupling agent remaining in the polymer system. This unreacted silane coupling agent can also volatilize, contaminating equipment and reducing the heat resistance of heat dissipation materials.

[0004] To solve these problems, various conventional techniques have been proposed for the surface treatment of fillers. For example, Patent Document 1 proposes a method of surface treatment by an integral method using a heat-conductive filler and dimethylpolysiloxane whose molecular chain segment ends are blocked with trialkoxysilyl groups. Patent Document 2 proposes a method of surface treatment by an integral method using a filler and dimethylpolysiloxane whose molecular chain segment ends are blocked with trialkoxysilyl groups and dimethylpolysiloxane whose both ends of the molecular chain are blocked with trialkoxysilyl groups. Further, Patent Document 3 proposes a method of surface treatment by an integral method using a filler and dimethylpolysiloxane whose molecular chain segment ends are blocked with dialkoxysilyl groups. Patent Document 4 proposes a method of surface treatment by an integral method using a filler and dimethylpolysiloxane whose molecular chain segment ends are blocked with trialkoxysilyl groups.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the method described in Patent Document 1, dimethylpolysiloxane in which the molecular chain ends are sealed with trialkoxysilyl groups is used as a surface treatment agent, and therefore, fillers surface-treated with this dimethylpolysiloxane have excellent compatibility with silicone. However, dimethylpolysiloxane with molecular chain ends sealed with trialkoxysilyl groups is poorly reactive, such as slow hydrolysis, similar to long-chain alkylsilanes, and surface treatment of fillers using the integral blend method requires stirring at high temperatures for a long time. Furthermore, the synthesis of dimethylpolysiloxane with molecular chain ends sealed with trialkoxysilyl groups is surprisingly difficult, and it was a material that could only be obtained by silicone rubber manufacturers or research laboratories dealing with organosilicon chemistry. In addition, because the dimethylpolysiloxane has trialkoxy groups, in condensed silicone systems, the dimethylpolysiloxane acts as a crosslinking agent, which presents a problem in adjusting the hardness of the composition.

[0007] The method described in Patent Document 2 uses dimethylpolysiloxane in which one or both ends of the molecular chain are sealed with trialkoxysilyl groups as a surface treatment agent. In this dimethylpolysiloxane, the trialkoxysilyl groups at the end of the molecular chain and the polysiloxane groups of the molecular chain are not directly bonded, but are bonded via hydrocarbon groups. Such dimethylpolysiloxane is synthesized by combining a polysiloxane having an SiH group at one end with a silane coupling agent having a vinyl group in the presence of a platinum catalyst. Until a few decades ago, polysiloxane having an SiH group at one end was a material that could only be obtained by silicone rubber manufacturers or research laboratories dealing with organosilicon chemistry, but now it is available for sale and on the market, making the synthesis of dimethylpolysiloxane easier. However, because dimethylpolysiloxane has some bonding via hydrocarbon groups, it can degrade easily at high temperatures. In addition, when synthesizing dimethylpolysiloxane, there were problems such as the low purity of the polysiloxane having an SiH group at one end as a raw material.

[0008] The method described in Patent Document 3 uses dimethylpolysiloxane in which the ends of the molecular chain fragments are sealed with dialkoxysilyl groups as a surface treatment agent. In this dimethylpolysiloxane, the dialkoxysilyl groups at the ends of the molecular chain fragments are not directly bonded to the polysiloxane groups of the molecular chain, but are bonded via hydrocarbon groups. The synthesis method of this dimethylpolysiloxane is the same as that described in Patent Document 2. It is known that dialkoxysilyl groups are more easily hydrolyzed than trialkoxysilyl groups, but when the molecular weight of the dialkoxysilyl group is large, the difference in hydrolytic properties of the trialkoxysilyl group is almost eliminated. Therefore, surface treatment of fillers using the dimethylpolysiloxane by integral blending requires stirring at high temperatures for a long time.

[0009] The method described in Patent Document 4 uses dimethylpolysiloxane, which has multiple trialkoxysilyl groups at the ends of its molecular chains (including a trifunctional resin structure), as a surface treatment agent. While the presence of multiple trialkoxysilyl groups in this dimethylpolysiloxane makes binding to fillers statistically probable, the difference in hydrolysis properties becomes almost negligible when the molecular weight of the siloxane portion is large. Therefore, surface treatment of fillers using the dimethylpolysiloxane via the integral blend method requires prolonged stirring at high temperatures. Furthermore, there is the problem of the difficulty in synthesizing the surface treatment agent itself.

[0010] This invention has been made in view of the above circumstances, and aims to provide a thermal conductive composition that yields a cured product with low viscosity, high thermal conductivity, and appropriate hardness even when a filler is highly filled into the polymer component. [Means for solving the problem]

[0011] As a result of diligent research to solve the aforementioned problems, the inventors have found that the problems can be solved by the following invention.

[0012] In other words, the present invention relates to the following: [1] A thermal conductive composition comprising a polymer component (A), a surface-treated filler (B) having a surface treatment with α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane having a weight-average molecular weight of 500 to 5,000, wherein the adhesion rate of the α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane to the filler is 20.0 to 50.0% by mass, and a silicon-containing oxide-coated nitride (C) having a nitride and a silicon-containing oxide coating film covering the nitride. [2] The thermal conductive composition according to [1] above, wherein the nitride is aluminum nitride. [3] The thermal conductive composition according to [1] or [2] above, wherein the 50% cumulative volume particle size of the filler is 0.1 to 30 μm, and the 50% cumulative volume particle size of the nitride is 10 to 150 μm. [4] The thermal conductive composition according to any one of [1] to [3] above, wherein the filler is at least one selected from the group consisting of metals, silicon, metal oxides, nitrides, and composite oxides. [5] The thermal conductive composition according to any one of [1] to [4] above, wherein the polymer component (A) is at least one selected from the group consisting of thermosetting resins, elastomers, and oils. [6] The thermal conductive composition according to any one of [1] to [5] above, wherein the polymer component (A) has a viscosity of 30 to 4,000,000 mPa·s at 25°C. [7] The thermal conductive composition according to any one of [1] to [6] above, wherein the content of the polymer component (A) is 1.0 to 15.0% by mass, the content of the surface treatment filler (B) is 30.0 to 96.0% by mass, and the content of the silicon-containing oxide coated nitride (C) is 3.0 to 55.0% by mass. [8] A cured product of any of the heat-conducting compositions described in [1] to [7] above. [9] A cured product of the thermal conductive composition described in [8] above, wherein the thermal conductivity is 3.0 W / m·K or higher. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a thermal conductive composition that yields a cured product with low viscosity, high thermal conductivity, and appropriate hardness even when a filler is highly filled into the polymer component. [Modes for carrying out the invention]

[0014] The present invention will be described in detail below with reference to one embodiment.

[0015] <Thermal conductive composition> The thermal conductive composition of this embodiment comprises a polymer component (A), a surface-treated filler (B) whose surface is surface-treated with α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane having a weight-average molecular weight of 500 to 5,000, wherein the adhesion rate of the α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane to the filler is 20.0 to 50.0% by mass, and a silicon-containing oxide-coated nitride (C) having a nitride and a silicon-containing oxide coating film covering the nitride. The thermal conductive composition of this embodiment, by including the surface treatment filler (B) and the silicon-containing oxide coated nitride (C), yields a cured product with low viscosity, high thermal conductivity, and appropriate hardness even when densely filled into the polymer component (A). The following provides a detailed explanation of each component.

[0016] [Polymer component (A)] The polymer component (A) used in this embodiment is not particularly limited and includes, for example, thermosetting resins, thermoplastic resins, elastomers, oils, etc. These may be used individually or in combination of two or more. From the viewpoint of obtaining the effects of the present invention, the polymer component (A) is preferably at least one selected from the group consisting of thermosetting resins, elastomers, and oils. Note that thermosetting resin refers to the state before curing, and in this specification, it is not limited to heat-curing types but also includes room-temperature curing types.

[0017] Examples of thermosetting resins include epoxy resins, phenolic resins, unsaturated polyester resins, melamine resins, urea resins, polyimides, and polyurethanes. Examples of thermoplastic resins include polyethylene, polypropylene and other polyolefins; polyester, nylon, ABS resin, methacrylic resin, acrylic resin, polyphenylene sulfide, fluororesin, polysulfone, polyetherimide, polyethersulfone, polyetherketone, liquid crystal polyester, thermoplastic polyimide, polylactic acid, and polycarbonate. Thermosetting resins and thermoplastic resins may be silicone-modified or fluororesin-modified. Specific examples of modified resins include silicone-modified acrylic resins and fluororesin-modified polyurethanes. Examples of elastomers include natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene, styrene-butadiene, chloroprene rubber, nitrile rubber, butyl rubber, ethylene-propylene rubber (EPM, EPDM), chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluororubber, and polyurethane rubber. Examples of oils include low molecular weight poly-α-olefins, low molecular weight polybutenes, silicone oils, and fluorinated oils. These may be used individually or in combination of two or more types.

[0018] From the viewpoint of availability of low-viscosity polymer components (A), polyurethane, silicone rubber, and silicone oil are preferred, with silicone rubber being more preferred. The silicone rubber may be addition-type silicone rubber or peroxide-type silicone rubber.

[0019] The polymer component (A) preferably has a viscosity of 30 to 4,000,000 mPa·s at 25°C, more preferably 50 to 3,500,000 mPa·s, and even more preferably 100 to 3,000,000 mPa·s. A viscosity of 30 mPa·s or higher provides excellent thermal stability, while a viscosity of 4,000,000 mPa·s or lower allows for a lower viscosity of the thermal conductive composition. The viscosity of polymer component (A) at 25°C can be measured using a rotational viscometer in accordance with JIS Z8803:2011 "Method for Measuring the Viscosity of Liquids," and specifically, it can be measured by the method described in the examples.

[0020] The content of polymer component (A) is 1.0 to 15.0% by mass, preferably 1.2 to 14.0% by mass, more preferably 1.4 to 12.0% by mass, and even more preferably 1.5 to 10.0% by mass, based on the total amount of the thermal conductive composition of this embodiment. When the content of the polymer component is 1.0% by mass or more, thermal conductivity can be imparted, and when it is 15.0% by mass or less, the viscosity of the composition and the hardness of the cured product can be appropriately controlled.

[0021] [Surface treatment filler (B)] The surface-treated filler (B) used in this embodiment is surface-treated with α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane having a weight-average molecular weight of 500 to 5,000, and the adhesion rate of the α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane to the filler is 20.0 to 50.0% by mass.

[0022] Examples of fillers include metals; silicon; oxides, nitrides, carbides, hydroxides, fluorides, and carbonates of metals, silicon, or boron; and carbon. Examples of the aforementioned metals include silver, gold, copper, iron, tungsten, stainless steel, aluminum, and carbonyl iron, and those that are easy to handle in air are preferably used. Examples of the aforementioned oxides include zinc oxide, aluminum oxide, magnesium oxide, silicon oxide, titanium oxide, iron oxide, calcium oxide, and cerium oxide. Compound oxides are also used. In particular, silicon oxide can be natural or synthetic, and specific examples include smokeless silica, wet silica, dry silica, fused silica, quartz powder, silica sand, silica stone, and anhydrous silicic acid. Examples of compound oxides include spinel, titanite, barium titanate, chrysoberyl, and ferrite. Examples of the nitrides include aluminum nitride, boron nitride, and silicon nitride. Examples of the carbides include silicon carbide and boron carbide. Examples of the hydroxides mentioned above include aluminum hydroxide, magnesium hydroxide, iron hydroxide, cerium hydroxide, and copper hydroxide. Examples of the fluoride include magnesium fluoride and calcium fluoride. Examples of the aforementioned carbonates include magnesium carbonate and calcium carbonate, and carbonate complex salts such as dolomite are also used. Examples of the aforementioned carbon include graphite and carbon black. These may be used individually or in combination of two or more types.

[0023] The filler is preferably at least one selected from the group consisting of metals, silicon, metal oxides, nitrides, and composite oxides, with metal oxides being more preferred, from the viewpoint of diverse particle sizes, diverse shapes, price, and availability.

[0024] Furthermore, considering the balance between thermal conductivity and cost, aluminum oxide (alumina) is preferred, and α-alumina is particularly preferred due to its high thermal conductivity. From the viewpoint of high thermal conductivity, aluminum nitride and boron nitride are suitably used, and from the viewpoint of low cost, silica, quartz powder, and aluminum hydroxide are suitably used.

[0025] From the viewpoint of imparting thermal conductivity, the thermal conductivity of the filler is preferably 0.5 W / m·K or higher, and more preferably 1.0 W / m·K or higher.

[0026] The shape of the filler is not particularly limited as long as it is a particle, but examples include perfectly spherical, spherical, rounded, flaky, crushed, and fibrous shapes. These may be used in combination.

[0027] From the viewpoint of high filling capacity of the polymer component (A), the particle size of the filler at 50% of the cumulative volume is preferably 0.1 to 30 μm, more preferably 0.2 to 28 μm, even more preferably 0.3 to 25 μm, and even more preferably 0.3 to 20 μm. In this specification, the particle size at 50% of the cumulative volume (hereinafter sometimes referred to as D50) can be determined from the particle size at which the cumulative volume is 50% in the particle size distribution measured using a laser diffraction particle size distribution analyzer.

[0028] The filler has a specific surface area of ​​preferably 0.05 to 10.0 m², as determined by the BET method. 2 / g, more preferably 0.08~9.0m 2 / g, more preferably 0.10 to 8.0m 2 The specific surface area is within the specified range, allowing for high filling of the polymer component (A) and increasing the thermal conductivity of the cured product. The specific surface area of ​​the filler can be measured using a specific surface area measuring device by the BET single-point method due to nitrogen adsorption, and specifically by the method described in the examples.

[0029] The filler may have undergone other surface treatments beforehand, such as water-resistant treatment or fluidity improvement. These surface treatments may be applied to the entire surface of the filler or to only a portion of it. Examples of fillers with the aforementioned surface treatments include fillers in which nanoparticles such as graphene are uniformly coated onto aluminum nitride, fillers in which silica is uniformly coated onto ceramic fillers, and film-deposited fillers in which a silicon oxide film is fabricated on the surface of aluminum nitride or the like using a sol-gel method or water glass to provide water resistance and insulation.

[0030] The α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane used for the surface treatment of the filler has a weight-average molecular weight (Mw) of 500 to 5,000, preferably 600 to 4,500, and more preferably 800 to 4,200. When the Mw is within the above range, the adhesion rate of the α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane to the filler can be set within the range defined in this invention. α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane may be used in combination of two or more types with different Mw values. The aforementioned Mw is the polystyrene-equivalent molecular weight, measured using gel permeation chromatography (GPC) and a calibration curve created using standard polystyrene samples with known molecular weights.

[0031] α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane has repeating units of dimethylsiloxane that are preferably integers from 4 to 64, more preferably from 8 to 60, and even more preferably from 10 to 56. When the repeating units of dimethylsiloxane are within the above range, the adhesion rate of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane to the filler can be set within the range defined in this invention.

[0032] The filler surface has functional groups such as hydroxyl groups, and these functional groups chemically bond with the trimethoxysilyl groups of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane, thereby immobilizing the hydrolysate of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane on the filler surface.

[0033] The adhesion rate of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane to the filler is 20.0 to 50.0% by mass, preferably 22.0 to 48.0% by mass, more preferably 24.0 to 46.0% by mass, and even more preferably 25.0 to 45.0% by mass. When the adhesion rate is 20.0% by mass or more, the curability of the thermal conductivity composition is good, and when it is 50.0% by mass or less, a thermal conductivity composition with low viscosity can be obtained even with high filling of polymer component (A), and the cured product can be made with appropriate hardness. The adhesion rate can be measured by a method compliant with JIS R1675:2007 "Combustion (high-frequency heating) - Infrared absorption method," and specifically by the method described in the examples.

[0034] The content of the surface treatment filler (B) is 30.0 to 96.0% by mass, preferably 35.0 to 90.0% by mass, more preferably 38.0 to 80.0% by mass, even more preferably 40.0 to 70.0% by mass, and even more preferably 45.0 to 65.0% by mass, based on the total amount of the heat conductive composition of this embodiment. When the content of the surface treatment filler (B) is 30.0% by mass or more, a heat conductive composition with low viscosity can be made even if the filler is highly filled into the polymer component (A), and the cured product can be made with an appropriate hardness. Furthermore, when the content of the surface treatment filler (B) is 96.0% by mass or less, the cured product of the heat conductive composition can be made with an appropriate hardness.

[0035] (Method for manufacturing surface treatment filler (B)) One method for producing the surface treatment filler (B) is to pre-treat the filler with a treatment solution containing α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane having a weight-average molecular weight of 500 to 5,000, an alcohol, and water, and then heat-treat it at a temperature of 140 to 180°C. The filler and the α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane can be those described above.

[0036] First, a treatment solution is prepared containing α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane, which has a weight-average molecular weight of 500 to 5,000, alcohol, and water. Examples of alcohols include ethanol, isopropanol, and butanol. These may be used individually or as a mixture of two or more. From the viewpoint of availability, the alcohol concentration contained in the processing solution is preferably 99.5 to 99.9% by mass. The water may be deionized water or distilled water. In addition to α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane, alcohol, and water, the processing solution may optionally contain acids such as hydrochloric acid and acetic acid; and organic solvents (excluding alcohol) such as acetone and methyl ethyl ketone. If the treatment solution contains an acid, the hydrogen ion concentration of the treatment solution is preferably 2 to 10% by mass from the viewpoint of hydrolysis rate and silanol stability.

[0037] The amount of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane (hereinafter also simply referred to as "polydimethylsiloxane") added to the filler can be determined from the minimum coverage area of ​​the polydimethylsiloxane. The minimum coverage area of ​​polydimethylsiloxane can be calculated using the following formula (I). Note that the occupied area of ​​the trimethoxysilyl group in polydimethylsiloxane is 13 × 10⁻⁶. -20 m 2 That is the case.

[0038]

number

[0039] The amount of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane added can be calculated using the following formula (II).

[0040]

number

[0041] In formula (II), the coverage rate is the theoretical amount of polydimethylsiloxane that covers the filler, and from the viewpoint of ease of filling, it is preferably 10 to 100%, more preferably 20 to 100%. When the coverage rate is 20% or more, foaming of the composition containing the surface treatment filler can be suppressed.

[0042] The alcohol content is preferably 150 to 400 parts by mass, more preferably 200 to 350 parts by mass, and even more preferably 200 to 300 parts by mass, per 100 parts by mass of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane. If the alcohol content is 150 parts by mass or more, the processing solution can be homogenized (compatibilized), and if it is 400 parts by mass or less, the processing solution can be turned into a slurry after being added to the filler.

[0043] The water content is preferably 0.5 to 10 parts by mass, more preferably 0.8 to 8 parts by mass, and even more preferably 1 to 6 parts by mass, per 100 parts by mass of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane. If the water content is 0.5 parts by mass or more, hydrolysis of the trimethoxy group progresses, and if it is 10 parts by mass or less, the treatment solution can be homogenized (compatibilized).

[0044] If the processing liquid contains an organic solvent (excluding alcohol), its content is preferably 50 to 300 parts by mass, more preferably 100 to 250 parts by mass, and even more preferably 100 to 200 parts by mass, per 100 parts by mass of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane. If the organic solvent content is 50 parts by mass or more, the processing liquid can be homogenized (compatibilized), and if it is 300 parts by mass or less, the processing liquid can be turned into a slurry after being added to the filler.

[0045] In a resealable container, mix α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane, alcohol, water, and any additional acids or organic solvents (excluding alcohol) as needed. The order in which these compounds are mixed is not particularly limited; they can be mixed in any order. Mixing can be performed by stirring with a motor equipped with stirring blades, a stirring bar in a magnetic stirrer, or by mixing each component in a container and then rotating the container with a mixing rotor. Mixing is preferably carried out at 23-80°C for 4-100 hours, and more preferably at 23-50°C for 4-72 hours.

[0046] Next, the processing liquid is added to the filler and stirred to perform pretreatment. Examples of agitation devices include rotary and orbital agitators, Nauters, high-speed mixers, Henschel mixers, and planetary mixers. Stirring is preferably carried out at 20-70°C for 1-120 minutes, and more preferably at 23-50°C for 1-30 minutes. After stirring, the mixture may be air-dried for 4 to 24 hours. Air-drying can simply be done at room temperature (25°C), or, if necessary, in a hot air circulating oven at a temperature of 50 to 80°C.

[0047] After pretreatment, the material is heat-treated at a temperature of 140-180°C to bake the treatment solution onto it. A heat treatment temperature of 140°C or higher can increase the adhesion rate of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane to the filler, while a temperature of 180°C or lower can prevent degradation of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane. The heat treatment temperature is preferably 145 to 175°C, more preferably 150 to 170°C. Furthermore, the heat treatment time is preferably 2 to 6 hours, more preferably 2 to 5 hours. If the heat treatment time is 2 hours or more, the surface treatment of the filler with α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane can be sufficiently performed, and if it is 6 hours or less, discoloration due to thermal degradation of the surface-treated filler can be suppressed.

[0048] The surface treatment filler (B) obtained in this manner may be washed with water or alcohol. Examples of alcohols used for washing include ethanol and propanol.

[0049] [Silicon-containing oxide-coated nitride (C)] The silicon-containing oxide coated nitride (C) used in this embodiment is a filler having a nitride and a silicon-containing oxide coating that covers the nitride. Examples of nitrides constituting the silicon-containing oxide coated nitride (C) include metal nitrides. Examples of metal nitrides include aluminum nitride, and commercially available or other known products can be used. Aluminum nitride can be obtained by any manufacturing method; for example, it may be obtained by a direct nitriding method in which metallic aluminum powder is directly reacted with nitrogen or ammonia, or by a reductive nitriding method in which alumina is heated in a nitrogen or ammonia atmosphere while carbon reduction is performed and the nitriding reaction is carried out simultaneously. In the following explanation, aluminum nitride will be used as an example of a nitride.

[0050] The shape of aluminum nitride is not particularly limited and can be amorphous (fragmented), spherical, elliptical, or plate-like (flaky). Furthermore, the 50% cumulative volume particle size of aluminum nitride is preferably 10 to 150 μm, more preferably 12 to 100 μm, and even more preferably 15 to 80 μm.

[0051] The specific surface area of ​​aluminum nitride, determined by the BET method, is preferably 0.03 to 3.5 m² from the viewpoint of filling the polymer component (A). 2 / g, more preferably 0.04~3.2m 2 The value is / g, and more preferably 0.05 to 3.0m 2 It is / g. The specific surface area of ​​aluminum nitride can be measured using a specific surface area measuring device by the BET single-point method due to nitrogen adsorption, and specifically by the method described in the examples.

[0052] From the viewpoint of improving moisture resistance, it is preferable for aluminum nitride to have a silicon-containing oxide film covering its surface. Furthermore, having a silicon-containing oxide film covering the surface of aluminum nitride improves water resistance and suppresses the generation of ammonia produced by hydrolysis, thereby making it less likely to inhibit the curing of polymer component (A). The silicon-containing oxide film may cover only a part of the surface of the aluminum nitride or cover all of it, but it is preferable that it covers all of the surface of the aluminum nitride. Because aluminum nitride has excellent thermal conductivity, aluminum nitride with a silicon-containing oxide coating on its surface (hereinafter also referred to as silicon-containing oxide coated aluminum nitride) also has excellent thermal conductivity. Examples of "silicon-containing oxides" in silicon-containing oxide coatings and silicon-containing oxide-coated aluminum nitride particles include silica and oxides containing both silicon and aluminum.

[0053] From the viewpoint of water resistance and thermal conductivity, the silicon-containing oxide coated aluminum nitride preferably has a silicon-containing oxide coating rate of 15-100%, more preferably 15-95%, even more preferably 15-90%, and particularly preferably 15-85% of the surface covered by the silicon-containing oxide coating, as determined by LEIS analysis.

[0054] The coating rate (%) of the silicon-containing oxide film (SiO2) covering the surface of aluminum nitride can be determined by the following formula through LEIS (Low Energy Ion Scattering) analysis. (S Al (AlN)-S Al (AlN + SiO2)) / S Al (AlN) × 100 In the above formula, S Al (AlN) is the area of the Al peak of aluminum nitride, and S Al (AlN + SiO2) is the area of the Al peak of silicon-containing oxide-coated aluminum nitride. The area of the Al peak can be determined from the analysis by low energy ion scattering (LEIS), which is a measurement method using an ion source and a noble gas as a probe. LEIS is an analysis method using a noble gas of several keV as incident ions and is an evaluation method enabling the analysis of the outermost surface composition (Reference: The TRC News 201610 - 04 (October 2016)). Incidentally, the coating rate of the silicon-containing oxide film covering the surface of FAN-f80-A1, which is an example of aluminum nitride, was 84% by LEIS analysis.

[0055] As a method for forming a silicon-containing oxide film on the surface of aluminum nitride, for example, there is a method having a first step of covering the surface of aluminum nitride with a siloxane compound containing a structure represented by the following formula (1), and a second step of heating the aluminum nitride covered with the siloxane compound at a temperature of 300°C or higher and 900°C or lower.

[0056]

Chemical formula

[0057] In formula (1), R is an alkyl group having 4 or less carbon atoms.

[0058] The structure represented by formula (1) is a hydrogensiloxane structural unit having a Si-H bond. In formula (1), R is an alkyl group having 4 or fewer carbon atoms, i.e., a methyl group, an ethyl group, a propyl group, or a butyl group, preferably a methyl group, an ethyl group, an isopropyl group, or a t-butyl group, and more preferably a methyl group.

[0059] The siloxane compound is preferably an oligomer or polymer containing the structure represented by formula (1) as a repeating unit. The siloxane compound may be linear, branched, or cyclic. The weight-average molecular weight of the siloxane compound is preferably 100 to 2,000, more preferably 150 to 1,000, and even more preferably 180 to 500, from the viewpoint of ease of forming a silicon-containing oxide film of uniform thickness. The weight-average molecular weight is the polystyrene equivalent value obtained by gel permeation chromatography (GPC).

[0060] As the siloxane compound, compounds represented by the following formula (2) and / or compounds represented by the following formula (3) are preferably used.

[0061] [ka]

[0062] In formula (2), R 1 and R 2 Each is independently either a hydrogen atom or a methyl group, and R 1 and R 2 At least one of them is a hydrogen atom. m is an integer from 0 to 10, preferably 1 to 5, more preferably 1, from the viewpoint of market availability and boiling point.

[0063] [ka]

[0064] In equation (3), n is an integer between 3 and 6, preferably between 3 and 5, and more preferably 4.

[0065] As the siloxane compound, a cyclic hydrogensiloxane oligomer in which n is 4 in formula (3) is particularly preferred from the viewpoint of ease of forming a good silicon-containing oxide film.

[0066] In the first step, the surface of the aluminum nitride is covered with a siloxane compound containing the structure shown in formula (1). In the first step, the method is not particularly limited as long as the surface of the aluminum nitride can be covered with a siloxane compound containing the structure shown in formula (1). Examples of methods for the first step include a dry mixing method in which the siloxane compound is added by spraying or other means while stirring the raw material aluminum nitride using a general powder mixing device, and then coated by dry mixing. Examples of the powder mixing apparatus include a Henschel mixer (manufactured by Nippon Coke Industries Co., Ltd.), a container-rotating V-blender, a double-cone blender, a ribbon blender with mixing blades, a screw-type blender, a sealed rotary kiln, and stirring by a stirrer in a sealed container using a magnetic coupling. The temperature conditions are not particularly limited, but are preferably in the range of 10 to 200°C, more preferably 20 to 150°C, and even more preferably 40 to 100°C.

[0067] Alternatively, a gas-phase adsorption method can be used in which the vapor of the siloxane compound alone or a mixed gas with an inert gas such as nitrogen gas is attached to or deposited onto the standing aluminum nitride surface. The temperature conditions are not particularly limited, but are preferably in the range of 10 to 200°C, more preferably 20 to 150°C, and even more preferably 40 to 100°C. If necessary, the system can also be pressurized or depressurized. In this case, a sealed system that allows for easy replacement of the gas in the system is preferred, such as a glass container, desiccator, or CVD apparatus.

[0068] The amount of the siloxane compound used in the first step is not particularly limited. In the aluminum nitride coated with the siloxane compound obtained in the first step, the amount of coating with the siloxane compound determines the specific surface area (m²) of the aluminum nitride as determined by the BET method. 2 Surface area 1m² calculated from ( / g) 2 The amount is preferably 0.1 mg to 1.0 mg per unit, more preferably 0.2 mg to 0.8 mg, and even more preferably 0.3 mg to 0.6 mg. When the amount of siloxane compound coating is within the above range, aluminum nitride having a silicon-containing oxide coating of uniform thickness can be obtained. Furthermore, the specific surface area (m²) of the aluminum nitride obtained by the BET method was 2 Surface area 1m² calculated from ( / g) 2 The amount of siloxane compound coating per unit is calculated by taking the mass difference of the aluminum nitride before and after coating with the siloxane compound and determining the specific surface area (m²) of the aluminum nitride using the BET method. 2 Surface area (m²) calculated from g / g 2 It can be found by dividing by ).

[0069] In the second step, the aluminum nitride covered with the siloxane compound obtained in the first step is heated at a temperature of 300°C to 800°C. This allows a silicon-containing oxide film to be formed on the surface of the aluminum nitride. The heating temperature is more preferably 400°C or higher, and even more preferably 500°C or higher.

[0070] The heating time is preferably 30 minutes to 6 hours, more preferably 45 minutes to 4 hours, and even more preferably 1 hour to 2 hours, from the viewpoint of ensuring sufficient reaction time and efficiently forming a good silicon-containing oxide film. The atmosphere during the heating treatment is preferably an atmosphere containing oxygen gas, for example, in the atmosphere (air).

[0071] After the heat treatment in the second step, silicon-containing oxide coated aluminum nitride particles may partially fuse together. In such cases, the particles can be crushed using a general-purpose grinder such as a roller mill, hammer mill, jet mill, or ball mill to obtain silicon-containing oxide coated aluminum nitride that is free from adhesion and aggregation.

[0072] Furthermore, after the completion of the second step, the first and second steps may be performed in sequence again. In other words, the process of performing the first and second steps in sequence may be repeated.

[0073] The content of the silicon-containing oxide coated nitride (C) is 3.0 to 55.0% by mass, preferably 5.0 to 54.0% by mass, more preferably 10.0 to 52.0% by mass, even more preferably 20.0 to 50.0% by mass, and even more preferably 30.0 to 50.0% by mass, based on the total amount of the thermal conductive composition of this embodiment. When the content of the silicon-containing oxide coated nitride (C) is 3.0% by mass or more, a thermal conductive composition with low viscosity can be obtained even when the filler is highly filled into the polymer component (A), and the cured product can be made with an appropriate hardness. Furthermore, when the content of the silicon-containing oxide coated nitride (C) is 55.0% by mass or less, the cured product of the thermal conductive composition can be made with an appropriate hardness.

[0074] [Other fillers] From the viewpoint of improving thermal conductivity, the thermal conductive composition of this embodiment preferably contains other fillers (hereinafter simply referred to as "other fillers") in addition to the surface-treated filler (B) described above. The other fillers may or may not be surface-treated. Other fillers include metal oxides, metal nitrides, and metal hydroxides. Examples of metal oxides include zinc oxide, alumina, magnesium oxide, silicon dioxide, and iron oxide. Examples of metal nitrides include boron nitride, aluminum nitride, and silicon nitride. Examples of metal hydroxides include aluminum hydroxide and magnesium hydroxide. Considering the balance between thermal conductivity and cost, aluminum oxide (alumina) is preferred, and α-alumina is particularly preferred due to its high thermal conductivity. From the viewpoint of high thermal conductivity, aluminum nitride and boron nitride are suitably used, and from the viewpoint of low cost, silica, quartz powder, and aluminum hydroxide are suitably used.

[0075] The particle size of the other fillers at 50% of the cumulative volume is preferably more than 30 μm and 100 μm or less, more preferably 35 to 90 μm, even more preferably 40 to 85 μm, and even more preferably 45 to 80 μm, from the viewpoint of improving thermal conductivity and achieving a high filling rate.

[0076] If the thermal conductive composition of this embodiment contains other fillers, their content is preferably 30 to 50% by mass, more preferably 34 to 48% by mass, and even more preferably 38 to 46% by mass, relative to the total amount of the thermal conductive composition. If the content of other fillers is 30% by mass or more, the thermal conductivity can be further increased, and if it is 50% by mass or less, the hardness of the cured product can be lowered to an appropriate hardness.

[0077] In addition to the components described above, the thermal conductive composition of this embodiment may optionally contain additives such as heat-resistant agents, flame retardants, plasticizers, vulcanizing agents, silane coupling agents, dispersants, and reaction accelerators, provided that they do not affect the curing form or physical properties and do not hinder the effects of the present invention. When the above-mentioned additives are used, the amount added is preferably 0.05 to 10.0% by mass, more preferably 0.10 to 8.0% by mass, and even more preferably 0.15 to 5.0% by mass, relative to the total amount of the heat-conducting composition.

[0078] In the thermal conductive composition of this embodiment, the total content of the polymer component (A), surface treatment filler (B), and silicon-containing oxide coated nitride (C) is preferably 90 to 100% by mass, more preferably 92 to 100% by mass, and even more preferably 95 to 100% by mass.

[0079] The heat-conducting composition of this embodiment can be obtained by adding a polymer component (A), a surface treatment filler (B), a silicon-containing oxide coated nitride (C), and other fillers and additives as needed to a stirring device, stirring, and kneading. The stirring device is not particularly limited and examples include a double-roll mixer, a kneader, a planetary mixer, a high-speed mixer, and a rotating / revolving stirrer.

[0080] The thermal conductive composition of this embodiment preferably has a viscosity of 100 to 1500 Pa·s, more preferably 100 to 1000 Pa·s, and even more preferably 100 to 800 Pa·s at 30°C. The viscosity can be measured using a flow viscometer in accordance with JIS K7210:2014, and specifically, it can be measured by the method described in the examples.

[0081] The thermal conductive composition of this embodiment yields a cured product with low viscosity, high thermal conductivity, and appropriate hardness, making it suitable for use in heat-generating electronic components such as electronic devices, personal computers, ECUs and batteries for automobiles.

[0082] <Cured product of thermal conductive composition> The thermal conductive composition of this embodiment can be cured by, for example, reacting the thermal conductive composition at room temperature (23°C) or by heating. If the polymer component (A) is of the room-temperature curing type, it may be cured by leaving it at a temperature of 20-25°C for about 1 to 10 days.

[0083] When the polymer component (A) is addition-type silicone rubber, a cured product can be obtained by reacting it at room temperature (23°C) or by heating, for example. When curing a thermally conductive composition containing addition-type silicone rubber as the polymer component (A) by heating, it is preferable to perform the heating without pressure, at a temperature of 50°C to 150°C for 5 minutes to 20 hours, and more preferably at a temperature of 60°C to 120°C for 10 minutes to 10 hours. When polymer component (A) is peroxide-type silicone rubber, a cured product can be obtained by reacting it at room temperature (23°C) or by heating, for example. When curing a thermally conductive composition containing peroxide-type silicone rubber as polymer component (A) by heating, it is preferable to perform primary vulcanization at a pressure of 0.1 to 1.0 MPa, a temperature of 50°C to 150°C, for 5 minutes to 2 hours, followed by secondary vulcanization at no pressure, a temperature of 100°C to 250°C, for 1 hour to 10 hours. More preferably, it is preferable to perform primary vulcanization at a pressure of 0.1 to 0.6 MPa, a temperature of 60°C to 120°C, for 10 minutes to 1 hour, followed by secondary vulcanization at no pressure, a temperature of 150°C to 230°C, for 2 hours to 6 hours.

[0084] The cured product of the thermal conductive composition of this embodiment preferably has a thermal conductivity of 3.0 W / m·K or higher, more preferably 3.2 W / m·K or higher. The thermal conductivity can be measured by a method in accordance with ISO 22007-2:2008, and specifically by the method described in the examples.

[0085] The cured product of the thermal conductive composition of this embodiment has a hardness of preferably 20 to 80, more preferably 22 to 70, and even more preferably 25 to 60, as measured in accordance with the ASTM D2240 hardness test (Shore 00). When the Shore 00 hardness is within the above range, a cured product with appropriate hardness can be obtained. The aforementioned Shore00 hardness can be measured specifically by the method described in the examples.

[0086] The cured product of the thermal conductive composition of this embodiment has an A hardness of 60 to 90, more preferably 65 to 90, and even more preferably 70 to 85, as measured in accordance with the hardness test (Type A) of JIS K7312:1996. When the A hardness is within the above range, a cured product with appropriate hardness can be obtained. The aforementioned hardness A can be measured specifically by the method described in the examples. [Examples]

[0087] The present invention will now be specifically described with reference to examples, but the present invention is not limited in any way by these examples.

[0088] (Raw material compound) Details of the raw material compounds used in Examples 1-9 and Comparative Examples 1-8 are as follows. [Filler] AES-12: Alumina, manufactured by Sumitomo Chemical Co., Ltd., D50 = 0.5 μm, specific surface area (BET method) = 5.8 m² 2 / g, thermal conductivity = 25 W / m·K, specific gravity = 3.98 g / cm 3 BAK-5: Alumina, manufactured by Shanghai Baitu Co., Ltd., D50 = 5 μm, specific surface area (BET method) = 0.4 m² 2 / g, thermal conductivity = 25 W / m·K, specific gravity = 3.98 g / cm 3 AKP30: Alumina, manufactured by Sumitomo Chemical Co., Ltd., D50 = 0.32 μm, specific surface area (BET method) = 7.0 m² 2 / g, thermal conductivity = 25 W / m·K, specific gravity = 3.98 g / cm 3 AA-3: Alumina, manufactured by Sumitomo Chemical Co., Ltd., D50 = 3.0 μm, specific surface area (BET method) = 0.54 m² 2 / g, thermal conductivity = 25 W / m·K, specific gravity = 3.98 g / cm 3 AA-18: Alumina, manufactured by Sumitomo Chemical Co., Ltd., D50 = 20 μm, specific surface area (BET method) = 0.15 m² 2 / g, thermal conductivity = 25 W / m·K, specific gravity = 3.98 g / cm 3 TFZ-S60X: Aluminum nitride, manufactured by Toyo Aluminum Co., Ltd., D50 = 55 μm, specific surface area (BET method) = 0.1 m² 2 / g, thermal conductivity = 170 W / m·K, specific gravity = 3.26 g / cm 3 TFZ-S30P: Aluminum nitride, manufactured by Toyo Aluminum Co., Ltd., D50 = 30 μm, specific surface area (BET method) = 0.2 m² 2 / g, thermal conductivity = 170 W / m·K, specific gravity = 3.26 g / cm 3 TFZ-N15P: Aluminum nitride, Toyo Aluminum Co., Ltd., D50 = 15 μm, specific surface area (BET method) = 0.9 m² 2 / g, thermal conductivity = 170 W / m·K, specific gravity = 3.26 g / cm 3 FAN-f80-A1: Aluminum nitride, manufactured by Furukawa Electronics Co., Ltd., D50 = 76 μm, specific surface area (BET method) = 0.05 m² 2 / g, thermal conductivity = 170 W / m·K, specific gravity = 3.26 g / cm 3

[0089] The D50, specific surface area, and thermal conductivity of the filler were measured using the following measurement method. (1) D50 The particle size distribution was measured using a laser diffraction particle size distribution analyzer (Microtrac-Bell Co., Ltd., product name: MT3300EXII), and the particle size at which the cumulative volume accounts for 50% (50% particle size D50) was determined.

[0090] (2) Specific surface area The specific surface area was measured using a single-point BET method with nitrogen adsorption, employing a surface area measuring device (manufactured by Mountec Co., Ltd., product name: Macsorb MS30).

[0091] (3) Thermal conductivity 50 g of filler was crushed, then 5% by mass of paraffin was added to the filler and kneaded. The resulting mixture was placed in a mold with a diameter of 25 mm and a thickness of 8 mm and molded by cold pressing. Next, the temperature was raised in an electric furnace from room temperature (20°C) to 200°C over 1 hour, and degreasing was performed for 2 hours while maintaining the temperature at 200°C. Subsequently, the temperature was raised at a rate of 400°C / hour, and the mixture was fired at a temperature of 1580°C for 4 hours, followed by natural cooling for 4 hours or more to obtain a sintered body. The thermal conductivity of the obtained sintered body was measured using a hot disk method thermophysical property measuring device (product name TPS 2500 S, manufactured by Kyoto Electronics Manufacturing Co., Ltd.) in accordance with ISO 22007-2:2008.

[0092] [Polymer component (A)] DOWSIL TM CY52-276: Solution A (mixture of vinyl group-containing dimethyl silicone rubber and platinum catalyst) and Solution B (mixture of vinyl group-containing dimethyl silicone rubber and crosslinking agent), manufactured by Dow Toray Corporation, viscosity at 25°C = 780 mPa·s, thermal conductivity = 0.2 W / m·K, specific gravity = 0.97 g / cm³ 3 DOWSIL TM EG-3100: Silicone rubber, manufactured by Dow-Toray Industries, Inc. Viscosity at 25°C = 320 mPa·s, thermal conductivity = 0.2 W / m·K, specific gravity = 0.97 g / cm³ 3 TSE201: Vinyl group-containing dimethyl silicone rubber, manufactured by Momentive, viscosity at 25°C: 1,000,000~3,000,000 mPa·s, thermal conductivity = 0.20 W / m·K, specific gravity = 0.97 g / cm³ 3

[0093] [Other ingredients] • KN320: Flame retardant, manufactured by Toda Kogyo Co., Ltd. • TC-1: Vulcanizing agent, manufactured by Momentive.

[0094] The viscosity and thermal conductivity of polymer component (A) were measured using the following measurement method. TM For the measurement of CY52-276, a mixture of solution A and solution B in a mass ratio of 1:1 was used. (1) Viscosity DOWSIL TM CY52-276 and DOWSIL TM The viscosity of EG-3100 was measured using a rotational viscometer (manufactured by Toki Sangyo Co., Ltd., product name: TVB-10, rotor No. 3) at 25°C and a rotational speed of 20 rpm, in accordance with the "Method for Measuring the Viscosity of Liquids" in JIS Z8803:2011. Furthermore, the viscosity of TSE201 was measured in accordance with JIS K7210:2014 using a flow viscometer (GFT-100EX, manufactured by Shimadzu Corporation) under the conditions of a temperature of 30°C, a die bore diameter of 1.0 mm, and a test force of 10 (weight of 1.8 kg). (2) Thermal conductivity The thermal conductivity of polymer component (A) was measured using a hot disk method thermophysical property measurement device (product name TPS 2500 S, manufactured by Kyoto Electronics Manufacturing Co., Ltd.) in accordance with ISO 22007-2:2008.

[0095] [α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane] • Surface treatment agent-1: α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane, weight-average molecular weight = 3,000, number of repeating units of dimethylsiloxane = 37, viscosity at 25°C = 25 mPa·s, minimum coverage area = 26.1 m² 2 / g, specific gravity=0.97g / cm 3 • Surface treatment agent-2: α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane, weight-average molecular weight = 1,400, number of repeating units of dimethylsiloxane = 15.3, viscosity at 25°C = 16 mPa·s, minimum coverage area = 55.9 m 2 / g, specific gravity=0.97g / cm 3 • Surface treatment agent-3: α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane, weight-average molecular weight = 4,000, number of repeating units of dimethylsiloxane = 50, viscosity at 25°C = 40 mPa·s, minimum coverage area = 19.6 m 2 / g, specific gravity=0.97g / cm 3

[0096] [Silane coupling agent] • Surface treatment agent-4: KBM-3103C, decyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight = 262.5, minimum coverage area = 298 m² 2 / g, specific gravity=0.89g / cm 3 • Surface treatment agent-5: Dynasylan(registered trademark) 9116, hexadecyltrimethoxysilane, molecular weight = 346.6, manufactured by Evonik Japan Co., Ltd., minimum coverage area = 226 m² 2 / g, specific gravity=0.89g / cm 3

[0097] The minimum coverage area of ​​the surface treatment agent was calculated using the following formula (i). In formula (i), the occupied area of ​​the trimethoxysilyl group is 13 × 10 for all of α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane, decyltrimethoxysilane, and hexadecyltrimethoxysilane. ‐20 m 2 That is the case.

[0098]

number

[0099] (Synthesis Example 1: Manufacturing of surface treatment filler (B1)) (1) Preparation of the treatment solution The amount of surface treatment agent-1 used was calculated using the following formula (ii). In formula (ii), the filler coverage was assumed to be 33.3%.

[0100]

number

[0101] 3.22 parts by mass of surface treatment agent-1, 8.05 parts by mass of isopropanol, and 0.06 parts by mass of deionized water were added to a vial, sealed, and stirred and mixed for 3 days at a temperature of 25°C and a rotation speed of 70 rpm using a mixing rotor (VMR-5A, manufactured by AS ONE Corporation) to obtain the treatment solution.

[0102] (2) Surface treatment of filler As fillers, 40.0 parts by mass of AES-12 (alumina) and 50.0 parts by mass of BAK-5 (alumina) were mixed using a rotary-orbit mixer (ARE-310, manufactured by Thinky Co., Ltd.) at a temperature of 25°C and a rotation speed of 2000 rpm for 20 seconds. 40 mL of the treatment solution obtained in (1) above was added to the resulting mixture using a dropper, and the mixture was stirred and mixed three times using the rotary-orbit mixer at a temperature of 25°C and a rotation speed of 2000 rpm for 20 seconds each time. The mixture was then air-dried at room temperature (25°C) for one day to evaporate the solvent. Next, the mixture was heat-treated at a temperature of 160°C for 4 hours to bake on surface treatment agent-1, and then cooled at room temperature (25°C) to obtain a surface-treated filler (B1) with surface treatment agent-1.

[0103] (3) Cleaning of surface treatment filler (B1) The obtained surface treatment filler (B1) was cleaned by the following procedure. 20 parts by mass of surface treatment filler (B1) were placed in a centrifuge tube, 10 parts by mass of isopropanol were added, the tube was covered and shaken up and down by hand for 30 seconds, and then stirred in a centrifuge (CN-2060, manufactured by AS ONE Corporation) at a rotation speed of 3000 rpm for 10 minutes to allow the surface treatment filler (B1) to settle. The supernatant was discarded and the precipitate was loosened, then 10 parts by mass of isopropanol were added, the tube was covered and shaken up and down by hand for 30 seconds, and then stirred in a centrifuge at a rotation speed of 3000 rpm for 10 minutes to allow the surface treatment filler (B1) to settle. The same procedure was repeated one more time, the supernatant was discarded and the precipitate was left in the centrifuge tube and air-dried for 1 day. After that, it was dried at a temperature of 100°C for 1 hour.

[0104] (Synthesis Examples 2-5: Manufacturing of surface treatment fillers (B2), (B3), and surface treatment fillers (b1), (b2)) Surface treatment fillers (B2), (B3), (b1), and (b2) for Synthesis Examples 2-5 were obtained in the same manner as Synthesis Example 1, except that the type and amount of treatment solution were changed as shown in Table 1, and the heat treatment temperature and heat treatment time were changed as shown in Table 1. In synthesis examples 2 and 3, the amount of surface treatment agent used was calculated using formula (ii) above, assuming a filler coverage of 33.3%. In synthesis examples 4 and 5, the amount of surface treatment agent used was calculated using formula (ii) above, assuming a filler coverage of 100%.

[0105] (Synthesis Example 6: Manufacturing of Surface Treatment Filler (B4)) (1) Preparation of the treatment solution The amount of surface treatment agent-1 used was calculated using formula (ii) above. In formula (ii), the filler coverage rate was assumed to be 33.3%. 2.76 parts by mass of surface treatment agent-1, 6.90 parts by mass of isopropanol, and 0.05 parts by mass of deionized water were added to a vial, sealed, and stirred and mixed for 3 days at a temperature of 25°C and a rotation speed of 70 rpm using a mixing rotor (VMR-5A, manufactured by AS ONE Corporation) to obtain the treatment solution.

[0106] (2) Surface treatment of filler As fillers, 60 parts by mass of AKP30 (alumina), 60 parts by mass of AA-3 (alumina), and 10 parts by mass of AA-18 (alumina) were mixed using a rotary-orbit mixer (ARE-310, manufactured by Shinky Co., Ltd.) at a temperature of 25°C and a rotation speed of 2000 rpm for 20 seconds. 40 mL of the treatment solution obtained in (1) above was added to the resulting mixture using a dropper, and the mixture was stirred and mixed three times using the rotary-orbit mixer at a temperature of 25°C and a rotation speed of 2000 rpm for 20 seconds each time. The mixture was then air-dried at room temperature (25°C) for one day to evaporate the solvent. Next, the mixture was heat-treated at a temperature of 160°C for 4 hours to bake on surface treatment agent-1, and then cooled at room temperature (25°C) to obtain a surface-treated filler (B4) with surface treatment agent-1.

[0107] (3) Cleaning of surface treatment filler (B4) The obtained surface treatment filler (B4) was cleaned according to the same procedure as in "(3) Cleaning of surface treatment filler (B1)" in Synthesis Example 1.

[0108] (Synthesis Example 7: Manufacturing of surface treatment filler (b3)) The surface treatment filler (b3) for Synthesis Example 7 was obtained in the same manner as for Synthesis Example 6, except that the type and amount of treatment solution were changed as listed in Table 1, and the heat treatment temperature and heat treatment time were changed as listed in Table 1. In addition, the amount of surface treatment agent used in synthesis example 7 was calculated assuming a filler coverage of 100% in formula (ii) above.

[0109] (Synthesis Example 8: Manufacturing of Surface Treatment Filler (B5)) (1) Preparation of the treatment solution The amount of surface treatment agent-1 used was calculated using formula (ii) above. In formula (ii), the filler coverage rate was assumed to be 33.3%. 4.02 parts by mass of surface treatment agent-1, 10.6 parts by mass of isopropanol, and 0.07 parts by mass of deionized water were added to a vial, sealed, and stirred and mixed for 3 days at a temperature of 25°C and a rotation speed of 70 rpm using a mixing rotor (VMR-5A, manufactured by AS ONE Corporation) to obtain the treatment solution.

[0110] (2) Surface treatment of filler As fillers, 40 parts by mass of AKP30 (alumina) and 50 parts by mass of AA-3 (alumina) were mixed using a rotary-orbit mixer (ARE-310, manufactured by Shinky Co., Ltd.) at a temperature of 25°C and a rotation speed of 2000 rpm for 20 seconds. 40 mL of the treatment solution obtained in (1) above was added to the resulting mixture using a dropper, and the mixture was stirred and mixed three times using the rotary-orbit mixer at a temperature of 25°C and a rotation speed of 2000 rpm for 20 seconds each time. The mixture was then air-dried at room temperature (25°C) for one day to allow the solvent to evaporate. Next, the mixture was heat-treated at a temperature of 160°C for 4 hours to bake on surface treatment agent-1, and then cooled at room temperature (25°C) to obtain a surface-treated filler (B5) with surface treatment agent-1.

[0111] (3) Cleaning of surface treatment filler (B5) The obtained surface treatment filler (B5) was cleaned according to the same procedure as in "(3) Cleaning of surface treatment filler (B1)" in Synthesis Example 1.

[0112] (Synthesis Example 9: Manufacturing of surface treatment filler (b4)) The surface treatment filler (b4) for Synthesis Example 9 was obtained in the same manner as for Synthesis Example 8, except that the type and amount of treatment solution were changed as listed in Table 1, and the heat treatment temperature and heat treatment time were changed as listed in Table 1. In addition, the amount of surface treatment agent used in synthesis example 9 was calculated assuming a filler coverage of 100% in formula (ii) above.

[0113] The obtained surface-treated fillers (B1) to (B5) and surface-treated fillers (b1) to (b4) were evaluated as follows. The results are shown in Table 1. [Adhesion rate of surface treatment agent to filler] The adhesion rate of the surface treatment agent was measured using a method compliant with JIS R1675:2007 "Combustion (high-frequency heating) - infrared absorption method". The total carbon content of the surface treatment agent and the total carbon content of the surface treatment filler after cleaning were measured and calculated using the following formula (iii). The carbon content of surface treatment agent-1 is 32.73% by mass, surface treatment agent-2 is 33.13% by mass, surface treatment agent-3 is 32.65% by mass, surface treatment agent-4 is 70.91% by mass, and surface treatment agent-5 is 75.79% by mass.

[0114]

number

[0115] [Table 1]

[0116] (Synthesis Example 10: Production of silicon-containing oxide-coated aluminum nitride (C1)) A vacuum desiccator made of 20mm thick acrylic resin with internal dimensions of 260mm x 260mm x 100mm, divided into upper and lower sections by a partition with through holes, was used. 100g of aluminum nitride (TFZ-S60X) was spread evenly on a stainless steel tray in the upper section and allowed to stand, while 20g of 2,4,6,8-tetramethylcyclotetrasiloxane (D4H) (manufactured by Tokyo Chemical Industry Co., Ltd.) was placed in a glass petri dish and allowed to stand in the lower section. The vacuum desiccator was then closed and heated in an 80°C oven for 30 hours. Safety measures were taken to release the hydrogen gas generated by the reaction through a valve attached to the vacuum desiccator. Next, the sample removed from the desiccator was placed in an alumina crucible and heat-treated in air at 700°C for 3 hours to obtain silicon-containing oxide-coated aluminum nitride (C1).

[0117] (Synthesis Example 11: Production of silicon-containing oxide-coated aluminum nitride (C2)) Except for using TFZ-S30P instead of TFZ-S60X as the aluminum nitride, silicon-containing oxide-coated aluminum nitride (C2) of Synthesis Example 12 was obtained in the same manner as in Synthesis Example 10.

[0118] (Synthesis Example 12: Production of silicon-containing oxide-coated aluminum nitride (C3)) The silicon-containing oxide-coated aluminum nitride (C3) of Synthesis Example 12 was obtained in the same manner as in Synthesis Example 10, except that TFZ-N15P was used instead of TFZ-S60X as the aluminum nitride.

[0119] (Synthesis Example 13: Production of silicon-containing oxide-coated aluminum nitride (C4)) Except for using FAN-f80-A1 instead of TFZ-S60X as aluminum nitride and performing heat treatment at 800°C for 3 hours, silicon-containing oxide coated aluminum nitride (C4) for Synthesis Example 13 was obtained in the same manner as in Synthesis Example 10.

[0120] (Example 1) (Manufacturing of thermal conductive compositions) As polymer component (A), vinyl group-containing dimethyl silicone rubber (DOWSIL TM 75.0 parts by mass of CY52-276 (a mixture of liquid A and liquid B in a mass ratio of 1:1) and 900.0 parts by mass of surface treatment filler (B1) were placed in a polyethylene container and stirred and mixed using a rotational / revolving mixer (manufactured by Thinky Co., Ltd.) at a rotation speed of 2000 rpm for 30 seconds. After cooling, the mixture was loosened, and 772.4 parts by mass of silicon-containing oxide-coated aluminum nitride (C1) was added as a silicon-containing oxide-coated nitride, and stirred and mixed using a rotational / revolving mixer at a rotation speed of 2000 rpm for 30 seconds to obtain the heat conductive composition of Example 1.

[0121] (Creating the sheet) A degassed heat-conducting composition was placed on a 0.1 mm thick polyester film treated with a fluorine release agent. Another 0.1 mm thick polyester film was then placed over it, ensuring no air was trapped inside. The mixture was then rolled and cured at 120°C for 60 minutes. Finally, it was left at room temperature (23°C) for one day to obtain a 2.0 mm thick sheet (cured heat-conducting composition).

[0122] (Examples 2, 3 and Comparative Examples 1-3: Manufacturing of thermal conductive compositions and sheets) The thermal conductive compositions and sheets for each example and comparative example were prepared in the same manner as in Example 1, except that the types and amounts of each component listed in Table 2 were changed. In Comparative Example 3, the polymer component (A) could not be filled with filler, and therefore a sheet could not be prepared.

[0123] (evaluation) The properties of the heat-conducting compositions and sheets of heat-conducting compositions obtained in each example and comparative example were measured under the measurement conditions shown below. The results are shown in Table 2.

[0124] (1) Filler content (volume %) The filler content (volume %) relative to the total amount of the heat conductive composition was calculated using the following formula (iv). In formula (iv) below, the volume of filler is the sum of the volume of surface-treated filler (B), the volume of silicon-containing oxide coated nitride (C), the volume of surface-treated fillers other than surface-treated filler (B), and the volume of other fillers. The volume of surface-treated filler (B) represents the volume of the filler before surface treatment, and the volume of resin components is the sum of the volume of polymer component (A) and the volume of the surface treatment agent used to surface-treat the filler.

[0125]

number

[0126] (2) Viscosity In accordance with JIS K7210:2014, measurements were taken using a flow viscometer (GFT-100EX, manufactured by Shimadzu Corporation) under the following conditions: temperature 30°C, die bore diameter 1.0 mm, and test force 10 (weight 1.8 kg).

[0127] (3) Hardness (Shore 00 hardness) The obtained 2.0 mm thick sheet was cut into strips measuring 20 mm wide x 30 mm long, and three of these strips were stacked to form a block, which was used as the measurement sample. The Shore 00 hardness of the measurement sample was measured using an Asker C hardness tester (Asker C rubber hardness tester, manufactured by Polymer Instruments Co., Ltd.) in accordance with the ASTM D2240 hardness test (Shore 00).

[0128] (4) Hardness (A hardness) A sheet with a thickness of 6 mm and a diameter of 45 mm was obtained and used as the measurement sample. In accordance with JIS K7312:1996, the A hardness of the measurement sample was measured using a rubber hardness tester (Polymer Instruments Co., Ltd., product name: Asker Rubber Hardness Tester Type A).

[0129] (5) Thermal conductivity The obtained 2.0 mm thick sheet was cut into strips measuring 20 mm wide x 30 mm long, and three of these strips were stacked to form a block. Two measurement samples were then prepared by covering the surface of the block with plastic wrap. The probe of a hot disk method measuring device (TPS-2500, manufactured by Kyoto Electronics Manufacturing Co., Ltd.), compliant with ISO 22007-2:2008, was set up so that it was sandwiched between the measurement samples from above and below, and the thermal conductivity was measured.

[0130] [Table 2]

[0131] The thermal conductive compositions of Examples 1 to 3, which include a surface-treated filler (B) and a silicon-containing oxide-coated nitride (C), all exhibit lower viscosity, moderate hardness with low hardness, and high thermal conductivity compared to the thermal conductive compositions of Comparative Examples 1 and 2, which include a filler surface-treated with a silane coupling agent. Comparative Example 3 shows that the untreated filler cannot be filled into the polymer component.

[0132] (Example 4: Manufacturing of thermal conductive composition and sheet) As polymer component (A), silicone rubber (DOWSIL TM 100.0 parts by mass of EG-3100 and 1621.0 parts by mass of surface treatment filler (B4) were placed in a polyethylene container and stirred and mixed in a rotating / revolving mixer (manufactured by Thinky Co., Ltd.) at a rotation speed of 2000 rpm for 30 seconds. After cooling, the mixture was loosened, and then 224.0 parts by mass of silicon-containing oxide coated aluminum nitride (C2) and 1487.0 parts by mass of silicon-containing oxide coated aluminum nitride (C4) were added as silicon-containing oxide coated nitrides, and stirred and mixed in a rotating / revolving mixer at a rotation speed of 2000 rpm for 30 seconds to obtain the heat conductive composition of Example 4. The sheet of Example 4 was obtained in the same manner as in Example 1.

[0133] (Examples 5-7 and Comparative Example 4: Manufacturing of thermal conductive composition and sheet) The thermal conductive compositions and sheets for each example and comparative example were obtained in the same manner as in Example 4, except that the types and amounts of each component listed in Table 3 were changed.

[0134] The properties of the heat-conducting compositions obtained in Examples 4-7 and Comparative Example 4, as well as sheets of the heat-conducting compositions, were measured under the aforementioned measurement conditions. The results are shown in Table 3.

[0135] [Table 3]

[0136] The thermal conductive compositions of Examples 4 to 7, which include a surface-treated filler (B) and a silicon-containing oxide-coated nitride (C), all exhibit lower viscosity, lower hardness, moderate hardness, and higher thermal conductivity compared to the thermal conductive composition of Comparative Example 4, which includes a filler surface-treated with a silane coupling agent.

[0137] (Example 8) (Manufacturing of thermal conductive compositions) As polymer component (A), 90.0 parts by mass of vinyl group-containing dimethyl silicone rubber (TSE201) and as surface treatment filler, 450.0 parts by mass of surface treatment filler (B5) were placed in a polyethylene container and stirred and mixed in a rotational / revolving mixer (manufactured by Thinky Co., Ltd.) at a rotation speed of 2000 rpm for 30 seconds. After cooling, the mixture was loosened, and then 386.0 parts by mass of silicon-containing oxide-coated aluminum nitride (C3) as a silicon-containing oxide-coated nitride, 2.0 parts by mass of KN320 as a flame retardant, and 5.0 parts by mass of TC-1 as a vulcanizing agent were added and stirred and mixed in a rotational / revolving mixer at a rotation speed of 2000 rpm for 30 seconds to obtain the heat conductive composition of Example 8.

[0138] (Creating the sheet) A mold with a φ45mm hole and a thickness of 6mm was placed on a 0.1mm thick polyester film treated with a fluorine release agent. The hole was filled with a degassed heat-conducting composition, and a 0.1mm thick polyester film was placed over it, ensuring no air was trapped inside. The mixture was then press-molded under a pressure of 0.5MPa, followed by primary vulcanization at 120°C for 30 minutes, and then secondary vulcanization in a hot air circulating oven at 200°C for 4 hours. The mixture was then left at room temperature (23°C) for one day to obtain a 6.0mm thick sheet.

[0139] (Examples 9 and Comparative Examples 5-8: Manufacturing of thermal conductive compositions and sheets) The thermal conductive compositions and sheets for each example and comparative example were prepared in the same manner as in Example 8, except that the types and amounts of each component listed in Table 4 were changed. In Comparative Examples 7 and 8, the polymer component (A) could not be filled with filler, and therefore sheets could not be prepared.

[0140] The properties of the thermal conductive compositions and sheets of thermal conductive compositions obtained in Examples 8 and 9 and Comparative Examples 5 and 6 were measured under the aforementioned measurement conditions. The results are shown in Table 4.

[0141] [Table 4]

[0142] Comparing the examples containing surface-treated filler (B) and silicon-containing oxide coated nitride (C), which have the same filler content (volume %), with the comparative examples containing a filler surface-treated with a silane coupling agent, it can be seen that the thermal conductive compositions of the examples yield cured products with low viscosity, low hardness, moderate hardness, and high thermal conductivity (see Examples 8 and Comparative Example 5, Examples 9 and Comparative Example 6). Furthermore, it can be seen that the untreated filler cannot be filled into the polymer component (see Comparative Examples 7 and 8).

Claims

1. Polymer component (A), A surface-treated filler (B) is formed by surface-treating the surface of the filler with α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane having a weight-average molecular weight of 500 to 5,000, wherein the adhesion rate of the α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane to the filler is 20.0 to 50.0% by mass, and A thermal conductive composition comprising a silicon-containing oxide-coated nitride (C) having a nitride and a silicon-containing oxide coating film covering the nitride, The dimethylsiloxane repeating units of the α-butyl-ω-(2-trimethoxysilylethyl)polydimethylsiloxane are 8 to 60. Thermal conductive composition.

2. The thermal conductive composition according to claim 1, wherein the nitride is aluminum nitride.

3. The thermal conductive composition according to claim 1, wherein the particle size of the filler at 50% of its cumulative volume is 0.1 to 30 μm, and the particle size of the nitride at 50% of its cumulative volume is 10 to 150 μm.

4. The thermal conductive composition according to claim 1, wherein the filler is at least one selected from the group consisting of metals, silicon, metal oxides, nitrides, and composite oxides.

5. The thermal conductive composition according to claim 1, wherein the polymer component (A) is at least one selected from the group consisting of thermosetting resins, elastomers, and oils.

6. The thermal conductive composition according to claim 1, wherein the polymer component (A) has a viscosity of 30 to 4,000,000 mPa·s at 25°C.

7. The heat conductive composition according to claim 1, wherein the content of the polymer component (A) is 1.0 to 15.0% by mass, the content of the surface treatment filler (B) is 30.0 to 96.0% by mass, and the content of the silicon-containing oxide coated nitride (C) is 3.0 to 55.0% by mass, based on the total amount of the heat conductive composition.

8. A cured product of the heat-conducting composition according to any one of claims 1 to 7.

9. A cured product of the thermal conductive composition according to claim 8, wherein the thermal conductivity is 3.0 W / m·K or higher.

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