Composition comprising specific boron nitride particles

Abstract

To provide a composition that can realize a heat dissipating material having improved heat conductivity.SOLUTION: One aspect of the present disclosure is a composition containing inorganic particles, and, in the composition, the inorganic particles include boron nitride particles having a maximum length of 80 μm or more and an aspect ratio of 1.5 or more, and particles other than boron nitride particles.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a composition containing specific boron nitride particles.

Background Art

[0002] In electronic components such as power devices, transistors, thyristors, and CPUs, it is necessary to efficiently remove the heat generated during use. Therefore, conventionally, a heat dissipation material containing inorganic particles having thermal conductivity and a resin has been used. For example, Patent Document 1 describes a thermally conductive grease characterized by containing 10 to 30% by mass of silicone oil having a kinematic viscosity at room temperature of 10 to 500 mm 2 / s, 40 to 60% by mass of spherical alumina fine powder having an average particle diameter of 1 μm or more and less than 3 μm, 4 to 10% by mass of aluminum nitride fine powder having an average particle diameter of 1 μm or more and less than 3 μm, and 10 to 30% by mass of spherical alumina ultrafine powder having an average particle diameter of 0.1 μm or more and less than 1 μm.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By using a plurality of types of inorganic particles in combination as in the thermally conductive grease described in Patent Document 1 above, the thermal conductivity of the heat dissipation material may be improved. However, there is still room for further improvement in such a heat dissipation material in order to obtain a better thermal conductivity.

[0005] Therefore, the main object of the present disclosure is to provide a composition capable of realizing a heat dissipation material with improved thermal conductivity.

Means for Solving the Problems

[0006] As a result of investigations by the present inventors, it has been found that by using boron nitride particles having a specific shape and other inorganic particles in combination as inorganic particles, the thermal conductivity of the resulting heat dissipation material can be further improved as compared with the case of using conventional inorganic particles in combination.

[0007] Therefore, one aspect of the present disclosure is a composition containing inorganic particles, wherein the inorganic particles include boron nitride particles having a maximum length of 80 μm or more and an aspect ratio of 1.5 or more, and particles other than the boron nitride particles.

[0008] The boron nitride particles may have an outer shell portion formed of boron nitride and a hollow portion surrounded by the outer shell portion.

[0009] The content of the boron nitride particles may be 0.5 to 10% by volume based on the total volume of the inorganic particles.

[0010] The composition may further contain a resin.

[0011] The composition may have a viscosity of 1000 Pa·s or less at 30°C and a shear rate of 10.0 s -1 -1.

[0012] The composition may be for grease.

Advantages of the Invention

[0013] According to the present disclosure, it is possible to provide a composition capable of realizing a heat dissipation material with further improved thermal conductivity.

Brief Description of the Drawings

[0014]

Figure 1

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present disclosure will be described in detail.

[0016] One embodiment of the present disclosure is a composition containing inorganic particles, wherein the inorganic particles include boron nitride particles (hereinafter also referred to as boron nitride particles A) having a maximum length of 80 μm or more and an aspect ratio of 1.5 or more, and particles other than the boron nitride particles A (hereinafter also referred to as particles B).

[0017] The composition according to one embodiment is a composition containing inorganic particles. By using the boron nitride particles A and the particles B in combination, a heat dissipation material with improved thermal conductivity can be realized as compared with the case of using conventional inorganic particles in combination (for example, when using boron nitride particles not corresponding to the boron nitride particles A and the particles B in combination). The reason is presumed to be that since the composition contains boron nitride particles having a maximum length greater than a predetermined value and an aspect ratio also greater than a predetermined value (that is, boron nitride particles having an elongated shape), the boron nitride particles are likely to form a heat transfer path with the particles B due to their shape. Therefore, this composition can be suitably used as a heat dissipation material (for example, heat dissipation grease, heat dissipation sheet).

[0018] The boron nitride particles A may be composed of a plurality of boron nitride flakes. The boron nitride flakes are formed of boron nitride and may have, for example, a flaky shape. In this case, the length in the longitudinal direction of the boron nitride flakes may be, for example, 1 μm or more and 10 μm or less. The plurality of boron nitride flakes constituting the boron nitride particles A may be physically in contact with each other or may be chemically bonded to each other.

[0019] From the viewpoint of more easily improving the thermal conductivity of the heat dissipation material, the maximum length of the boron nitride particles A may be 100 μm or more, 125 μm or more, 150 μm or more, 175 μm or more, 200 μm or more, 225 μm or more, 250 μm or more, 300 μm or more, or 350 μm or more. The maximum length of the boron nitride particles A may be 1000 μm or less, or 500 μm or less.

[0020] The maximum length of the boron nitride particles A means the maximum length among the straight-line distances between any two points on one boron nitride particle A when observing the boron nitride particles A with a scanning electron microscope (SEM). The measurement of the maximum length may be carried out by importing the SEM image into image analysis software (for example, "Mac-view" manufactured by Mountech Co., Ltd.).

[0021] From the viewpoint of being more likely to improve the thermal conductivity of the heat dissipation material, the aspect ratio of the boron nitride particles A may be 1.7 or more, 2.0 or more, 3.0 or more, 5.0 or more, or 7.0 or more. The aspect ratio of the boron nitride particles A may be 12.0 or less, 10.0 or less, 9.5 or less, 9.0 or less, or 8.0 or less.

[0022] The aspect ratio of the boron nitride particles A is the maximum length (the maximum length in the longitudinal direction) L of the boron nitride particles A described above A and the maximum length L A of the boron nitride particles A in the direction perpendicular to the direction (longitudinal direction) having the maximum length L (the maximum length in the short transverse direction) L B is defined as the ratio (L A / L B ). The maximum length L in the short transverse direction B can be measured in the same manner as the maximum length L in the longitudinal direction A .

[0023] Boron nitride particle A may be hollow from the viewpoint of more easily improving the thermal conductivity of the heat dissipation material, and may have an outer shell portion formed of boron nitride and a hollow portion surrounded by the outer shell portion. The hollow portion may be formed along the longitudinal direction of the boron nitride particle A, and may have an elongated shape substantially similar to the external shape of the boron nitride particle A. Further, when the boron nitride particle A is hollow, at least one of both ends in the longitudinal direction of the boron nitride particle A may be an open end, and both ends may be open ends. The open end may communicate with the above-described hollow portion. When the boron nitride particle A is hollow and at least one of both ends in the direction having the maximum length of the boron nitride particle A is an open end, if a resin or the like lighter than the boron nitride particle A is filled in the hollow portion, weight reduction of the composition can be expected. Therefore, when the boron nitride particle A has a hollow portion, even if the content on a mass basis is small compared to the case where solid boron nitride particles are used as the boron nitride particle A, a heat transfer path can be formed with the particle B. Therefore, it is considered that even if the content of the boron nitride particle A is small, the thermal conductivity of the heat dissipation material can be more easily improved.

[0024] Boron nitride particle A may have a cross section in which the area ratio of the hollow portion to the total area of the outer shell portion and the hollow portion is 5% or more. The area ratio of the hollow portion of the boron nitride particle A can be obtained by taking in a cross-sectional image (SEM image) of the boron nitride particle A into image analysis software (for example, "Mac-view" manufactured by Mountech Co., Ltd.) and calculating it. From the viewpoint of reducing the weight of the composition, boron nitride particle A may have a cross section in which the above area ratio is 10% or more, 20% or more, 30% or more, 40% or more, or 50% or more. Boron nitride particle A may have a cross section in which the above area ratio is 90% or less or 80% or less.

[0025] From the perspective of reducing the weight of the composition, the thickness of the outer shell of boron nitride particles A may be 50 μm or less, 30 μm or less, or 15 μm or less. From the perspective of easily maintaining the shape of boron nitride particles A, the thickness of the outer shell may be 1 μm or more or 3 μm or more. The thickness of the outer shell is defined as the average value of the lengths of the portions drawn on each outer shell of the straight line when a straight line with the maximum straight-line distance between any two points on the cross-section of boron nitride particles A is drawn in the observation image obtained by observing the cross-section in a direction perpendicular to the longitudinal direction of boron nitride particles A with SEM.

[0026] The external shape of boron nitride particles A may be an ellipsoid of revolution, columnar (rod-shaped), conical (such as conical), plate-shaped (flat plate-shaped, curved plate-shaped, etc.), dumbbell-shaped, etc., and may also be a bent shape. The boron nitride particles may have a branched structure that branches in two or more directions.

[0027] Boron nitride particles A may be boron nitride particles (boron nitride particles having elasticity) that return to a shape close to the original shape when the load is removed even if they are deformed by an external load. The fact that boron nitride particles A are boron nitride particles having elasticity can be confirmed, for example, by subjecting them to a loading and unloading test that includes a loading step of gradually applying a load from 0.2 mN to 20 mN at a loading rate of 0.27 mN / second in the short axis direction of boron nitride particles A and compressing them, and an unloading step of gradually unloading to 0.2 mN at an unloading rate of 0.27 mN / second in this order, and at least a part of the length of the boron nitride particles compressed in the loading step returns in the unloading step. Since boron nitride particles A being boron nitride particles having elasticity makes it easier to maintain the heat conduction path in the heat dissipation material even when used in a manner where pressure or stress is applied to the boron nitride particles, it is preferable that boron nitride particles A are boron nitride particles having elasticity. For example, when used as a heat dissipation grease used between a substrate and a heat sink, a pressure of about 0.1 to 1.0 MPa is applied when arranging the heat dissipation grease, but since boron nitride particles A are boron nitride particles having elasticity, it is considered that the heat conduction path can be maintained in the heat dissipation material even after arranging the heat dissipation grease.

[0028] The boron nitride particles A may consist essentially of only boron nitride. The fact that the boron nitride particles A consist essentially of only boron nitride can be confirmed by detecting only the peaks derived from boron nitride in X-ray diffraction measurement.

[0029] The content of the boron nitride particles A may be 0.5% by volume or more, 1% by volume or more, 1.5% by volume or more, 2% by volume or more, or 2.5% by volume or more based on the total volume of the composition. The content of the boron nitride particles A may be 50% by volume or less, 40% by volume or less, 30% by volume or less, 20% by volume or less, 10% by volume or less, 7% by volume or less, 5% by volume or less, 4% by volume or less, or 3% by volume or less based on the total volume of the composition.

[0030] The content of the boron nitride particles A may be 0.5% by volume or more, 1% by volume or more, 1.5% by volume or more, 2% by volume or more, 2.5% by volume or more, 3% by volume or more, or 3.5% by volume or more based on the total volume of the inorganic particles. The content of the boron nitride particles A may be 50% by volume or less, 40% by volume or less, 30% by volume or less, 20% by volume or less, 10% by volume or less, 7% by volume or less, 5% by volume or less, 4.5% by volume or less, or 4% by volume or less based on the total volume of the inorganic particles.

[0031] The boron nitride particles A can be obtained, for example, by a production method comprising: a step of mixing 2 to 100 parts by mass of boric acid with 100 parts by mass of boron carbide powder having an average particle diameter of 5 to 100 μm to obtain a mixture; a step of filling the carbon crucible with the mixture; a step of covering the opening of the carbon crucible with a carbon sheet, sandwiching the carbon sheet between the lid of the carbon crucible and the carbon crucible, and heating the covered carbon crucible in a resistance heating furnace under a nitrogen gas atmosphere at 1450 to 2400 °C and 0.3 to 1.0 MPa for 3 to 40 hours to generate boron nitride particles on the carbon sheet, and recovering the boron nitride particles generated on the carbon sheet. For the obtained boron nitride particles A, crushing, sieving, washing, impurity removal, drying, etc. may be appropriately performed.

[0032] Particle B may be, for example, alumina particles, boron nitride particles, aluminum nitride particles, or silicon carbide particles. The external shape of Particle B may be spherical, ellipsoidal of revolution, columnar, scaly, or the like. Particle B may be an aggregate of a plurality of particles.

[0033] The average particle diameter of Particle B may be 0.1 μm or more, 0.5 μm or more, 1 μm or more, 10 μm or more, 30 μm or more, or 50 μm or more. The average particle diameter of Particle B may be, for example, 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, or 50 μm or less. The average particle diameter of Particle B is the d50 diameter in the volume-based particle size distribution and can be measured with a laser diffraction particle size distribution measuring device.

[0034] The aspect ratio of Particle B may be 1.0 or more, 1.2 or more, 1.4 or more, or 1.5 or more. The aspect ratio of Particle B may be, for example, 10.0 or less, 8.0 or less, 6.0 or less, 4.0 or less, 2.0 or less, or 1.5 or less. The aspect ratio of Particle B is defined as the ratio (L C / L C ) of the maximum length (the maximum length in the longitudinal direction) L of Particle B to the maximum length (the maximum length in the direction perpendicular to the direction (longitudinal direction) having the maximum length L D in the direction perpendicular to the longitudinal direction) of Particle B. The maximum length L C in the longitudinal direction and the maximum length L D in the short direction of Particle B can be measured in the same manner as the maximum length L C in the longitudinal direction and the maximum length L D in the short direction of the above-mentioned boron nitride particles A. A and the maximum length L B in the short direction.

[0035] The content of Particle B may be 5% by volume or more, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, or 60% by volume or more based on the total volume of the composition. The content of Particle B may be 80% by volume or less, 75% by volume or less, 70% by volume or less, 65% by volume or less, or 60% by volume or less based on the total volume of the composition.

[0036] The content of Particle B may be 50% by volume or more, 60% by volume or more, 70% by volume or more, 80% by volume or more, 90% by volume or more, 93% by volume or more, 95% by volume or more, 95.5% by volume or more, or 96% by volume or more based on the total volume of the inorganic particles. The content of Particle B may be 99.5% by volume or less, 99% by volume or less, 98.5% by volume or less, 98% by volume or less, 97.5% by volume or less, 97% by volume or less, or 96.5% by volume or less based on the total volume of the inorganic particles.

[0037] Particle B may contain two or more types of particles that differ in at least one selected from the group consisting of composition (components constituting Particle B), average particle diameter, and aspect ratio.

[0038] The content of the inorganic particles may be 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, or 60% by volume or more based on the total volume of the composition, and may be 85% by volume or less, 80% by volume or less, 75% by volume or less, 70% by volume or less, 65% by volume or less, or 60% by volume or less.

[0039] In addition to the above inorganic particles, the composition according to one embodiment may further contain a dispersion medium for dispersing the inorganic particles. The dispersion medium may be, for example, a resin. That is, the composition may further contain a resin. The resin may be, for example, a thermosetting or photocurable resin, or a thermoplastic resin.

[0040] The resin may be, for example, a silicone resin, an epoxy resin, a silicone rubber, an acrylic resin, a phenolic resin, a melamine resin, a urea resin, an unsaturated polyester, a fluororesin, a polyimide, a polystyrene, a polyolefin, a polyamide, a polyamideimide, a polyetherimide, a polybutylene terephthalate, a polyethylene terephthalate, a polyphenylene ether, a polyphenylene sulfide, an all-aromatic polyester, a polysulfone, a liquid crystal polymer, a polyethersulfone, a polycarbonate, a maleimide-modified resin, an ABS (acrylonitrile-butadiene-styrene) resin, an AAS (acrylonitrile-acrylic rubber-styrene) resin, or an AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin. From the viewpoint of excellent heat resistance, flexibility, and adhesion to a heat sink or the like, the resin may be a silicone resin.

[0041] The silicone resin may be a silicone (a compound having a siloxane bond) having a functional group such as a vinyl group, an alkyl group, an aryl group, or a hydrosilyl group. The silicone resin may contain at least one selected from the group consisting of a silicone having a vinyl group and a silicone having a hydrosilyl group.

[0042] The weight average molecular weight of the resin may be 1000 to 1000000 or 2000 to 800000. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) and measured by conversion to polystyrene.

[0043] The content of the resin may be 15% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, or 60% by volume or more, and may be 80% by volume or less, 70% by volume or less, 60% by volume or less, 50% by volume or less, or 40% by volume or less, based on the total volume of the composition.

[0044] The dispersion medium may be a monomer. That is, the composition may further contain a monomer. The monomer may have a polymerizable carbon-carbon double bond. The monomer may have, for example, an acryloyl group, a methacryloyl group, an allyl group, a methallyl group, or a vinyl group. Examples of the monomer include acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, itaconic acid, cinnamic acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, maleic acid monocyclohexyl, fumaric acid monocyclohexyl, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether, methyl acrylate, ethyl acrylate, butyl acrylate, 2-chloroethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-chloroethyl methacrylate, 2-chloroethyl vinyl ether, vinyl benzyl chloride, vinyl chloroacetate, allyl chloroacetate, and diallyl fumarate.

[0045] The content of the monomer may be 15% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, or 60% by volume or more, based on the total mass of the composition, and may be 80% by volume or less, 70% by volume or less, 60% by volume or less, 50% by volume or less, or 40% by volume or less.

[0046] The composition may further contain a coupling agent. The coupling agent may be a silane coupling agent. The silane coupling agent may have a reactive double bond and may have a vinyl group, an allyl group, etc.

[0047] Examples of the silane coupling agent include allyl triethoxysilane, allyl chlorodimethylsilane, allyl trimethoxysilane, allyl trichlorosilane, chlorodimethylvinylsilane, diethoxymethylvinylsilane, dimethoxymethylvinylsilane, trichlorovinylsilane, vinyl trimethoxysilane, dimethylethoxyvinylsilane, and vinyl tris(2-methoxyethoxy)silane.

[0048] The content of the coupling agent may be 0.01 to 10% by mass or 0.1 to 5% by mass based on the total mass of the composition.

[0049] The composition may further contain other components. The other components may be a curing agent, a curing accelerator (curing catalyst), a wetting dispersant, a surface conditioner, an addition reaction catalyst, organic particles, a pigment, etc.

[0050] Examples of the curing agent include a phenol novolak compound, an acid anhydride, an amino compound, an imidazole compound, etc.

[0051] Examples of the curing accelerator (curing catalyst) include phosphorus-based curing accelerators such as tetraphenylphosphonium tetraphenylborate and triphenyl phosphate, imidazole-based curing accelerators such as 2-phenyl-4,5-dihydroxymethylimidazole, and amine-based curing accelerators such as boron trifluoride monoethylamine.

[0052] Examples of the wetting dispersant include phosphate esters, carboxylic acid esters, polyesters, acrylic copolymers, block copolymers, etc.

[0053] Examples of the surface conditioner include acrylic surface conditioners, silicone surface conditioners, vinyl conditioners, fluorine-based surface conditioners, etc.

[0054] The viscosity of the composition at 30 °C and a shear rate of 10.0 S -1 may be 1000 Pa·s or less, 500 Pa·s or less, 300 Pa·s or less, or 100 Pa·s or less, and may be 50 Pa·s or more. The viscosity can be measured using a rheometer (for example, "MARS3" manufactured by Thermo Fisher Scientific, "MCR92" manufactured by Anton Paar).

[0055] When the dispersion medium contains a curable component (such as a thermosetting or photocurable resin, monomer, etc.), the composition may be cured. The cured composition is also included in the composition in this specification. The method of curing the composition can be appropriately selected according to the type of the dispersion medium (resin, monomer) contained in the composition. For example, when the composition contains a silicone resin, the composition may be cured by allowing a crosslinking reaction to proceed. The composition can be cured, for example, by adding an addition reaction catalyst (such as a platinum-based catalyst) to the composition. The addition reaction catalyst may be added to the composition and heated to allow the crosslinking reaction to proceed.

[0056] The above composition can be used as a heat dissipation material (such as a heat dissipation grease, a heat dissipation sheet). The composition may be used after curing or may be used without curing.

[0057] The composition can be produced, for example, by a method for producing a composition including a step of preparing inorganic particles (boron nitride particles A and B) (preparation step) and a step of mixing the inorganic particles with a dispersion medium (mixing step). Another embodiment of the present disclosure is such a method for producing a composition.

[0058] In the mixing step, the addition amount of boron nitride particles A may be 0.5% by volume or more, 1% by volume or more, 1.5% by volume or more, 2% by volume or more, or 2.5% by volume or more, and may be 50% by volume or less, 40% by volume or less, 30% by volume or less, 20% by volume or less, 10% by volume or less, 7% by volume or less, 5% by volume or less, 4% by volume or less, or 3% by volume or less, based on the total volume of the composition.

[0059] In the mixing step, the addition amount of boron nitride particles A may be 0.5% by volume or more, 1% by volume or more, 1.5% by volume or more, 2% by volume or more, 2.5% by volume or more, 3% by volume or more, or 3.5% by volume or more, and may be 50% by volume or less, 40% by volume or less, 30% by volume or less, 20% by volume or less, 10% by volume or less, 7% by volume or less, 5% by volume or less, 4.5% by volume or less, or 4% by volume or less, based on the total volume of the inorganic particles.

[0060] In the mixing step, the addition amount of particle B may be 5% by volume or more, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, or 60% by volume or more, based on the total volume of the composition, and may be 80% by volume or less, 75% by volume or less, 70% by volume or less, 65% by volume or less, or 60% by volume or less.

[0061] In the mixing step, the addition amount of particle B may be 50% by volume or more, 60% by volume or more, 70% by volume or more, 80% by volume or more, 90% by volume or more, 93% by volume or more, 95% by volume or more, 95.5% by volume or more, or 96% by volume or more, based on the total volume of the inorganic particles, and may be 99.5% by volume or less, 99% by volume or less, 98.5% by volume or less, 98% by volume or less, 97.5% by volume or less, 97% by volume or less, or 96.5% by volume or less.

[0062] In the mixing step, the addition amount of the inorganic particles may be 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, or 60% by volume or more, based on the total volume of the composition, and may be 85% by volume or less, 80% by volume or less, 75% by volume or less, 70% by volume or less, 65% by volume or less, or 60% by volume or less.

Examples

[0063] Hereinafter, the present disclosure will be specifically described by way of examples. However, the present disclosure is not limited only to the following examples.

[0064] [Production of boron nitride particles A] 100 parts by mass of boron carbide powder having an average particle diameter of 10 μm and 9 parts by mass of boric acid were mixed, filled into a carbon crucible, the opening of the carbon crucible was covered with a carbon sheet (manufactured by NeoGraf), and the carbon sheet was fixed by sandwiching the carbon sheet between the lid of the carbon crucible and the carbon crucible. The covered carbon crucible was heated in a resistance heating furnace under a nitrogen gas atmosphere at 2000 °C and 0.85 MPa for 20 hours, and boron nitride particles were generated on the carbon sheet. An SEM image of the boron nitride particles (boron nitride particles A) recovered from the carbon sheet is shown in Fig. 1. The boron nitride particles A indicated by the arrow in Fig. 1 had a maximum length of 373 μm and an aspect ratio of 7.5.

[0065] [Loading and unloading test] Arbitrarily select 10 boron nitride particles A from the obtained boron nitride particles, and use a micro compression tester (manufactured by Shimadzu Corporation, MCT series) to gradually apply a load from 0.2 mN to 20 mN at a loading rate of 0.27 mN / second in the short axis direction of the boron nitride particles A for compression, and a unloading process of gradually unloading to 0.2 mN at a unloading rate of 0.27 mN / second. All 10 boron nitride particles A subjected to the loading and unloading test had at least a part of the length in the short axis direction of the boron nitride particles A compressed in the loading process return in the unloading process. It was confirmed by the loading and unloading test that the boron nitride particles A are boron nitride particles having elasticity.

[0066] [Manufacture of composition] In order to manufacture the composition, in addition to the above boron nitride particles A, the following raw materials were used. <Particle B> Boron nitride particles B1: Flaky boron nitride particles having a maximum length of 30 μm Boron nitride particles B2: Massive boron nitride particles having a maximum length of 85 μm and an aspect ratio of 2 or less. Alumina particles B3: Average particle diameter 45 μm, manufactured by Denka Co., Ltd., DAW45S Alumina particles B4: Average particle diameter 20 μm, manufactured by Denka Co., Ltd., DAW20 Alumina particles B5: average particle size 5 μm, manufactured by Denka Co., Ltd., DAW05 Alumina particles B6: average particle size 3 μm, manufactured by Denka Co., Ltd., DAW03 Alumina particles B7: average particle size 0.4 μm, manufactured by Denka Co., Ltd., ASFP40 Alumina particles B8: average particle size 0.5 μm, manufactured by Sumitomo Chemical Co., Ltd., AA05 Alumina particles B9: average particle size 2 μm, manufactured by Sumitomo Chemical Co., Ltd., AA2 <Dispersion medium> Silicone resin 1: silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd., KF96-100CS Silicone resin 2: silicone having vinyl groups at both ends, weight average molecular weight 25,000, manufactured by Momentive, XE14-B8530A Silicone resin 3: silicone having vinyl groups at both ends and hydrosilyl groups in the molecule, weight average molecular weight 25,000, manufactured by Momentive, XE14-B8530B Silicone resin 4: silicone having a vinyl group, weight average molecular weight 500,000, manufactured by Momentive, SRH-32 <Other components> Pigment: manufactured by Resin Color Industry Co., Ltd., Resin Black Silane coupling agent: allyltrimethoxysilane, manufactured by Dow Corning Toray Co., Ltd., Z6210

[0067] (Examples 1, 2 and Comparative Example 1) The inorganic particles shown in Table 1 and silicone resin 1 were mixed using a high-speed mixer to obtain a composition. In the composition, the content of the inorganic particles was 73% by volume, and the content of silicone resin 1 was 27% by volume. Also, the content (% by volume) of each particle based on the total volume of the inorganic particles in the obtained composition was as shown in Table 1.

[0068] [Measurement of viscosity] The viscosities of the compositions of Examples 1, 2 and Comparative Example 1 were measured using a rheometer (MARS3 manufactured by Thermo Fisher Scientific) under the following conditions. The measurement results are shown in Table 1. <Conditions> ·Measurement mode: Rotation ·Temperature: 30 °C ·Measurement jig: Φ25 parallel plate ·Gap: 1 mm ·Shear rate: 10.0 s -1

[0069] [Measurement of thermal conductivity] Using a thermal resistance measurement device (manufactured by Mentor Graphics, DynTIM), the thermal resistance values at each thickness of the compositions obtained in Example 1, Example 2, and Comparative Example 1 were measured under the following conditions. The relationship between the measured thermal resistance values and the thickness was approximated by a straight line, and the thermal conductivity was calculated from the slope of the obtained straight line and the area of the measurement part. The measurement results of the thermal conductivity are shown in Table 1. [Conditions] ·Cold plate temperature: 25 °C ·Measurement mode: Pressure control mode of Type 2 "Visco-elastic solids" (pressure: about 4 kPa) ·Thickness: 200 μm, 250 μm, 300 μm

[0070] [Table 1]

[0071] (Example 3 and Comparative Examples 2 to 4) Weighed the inorganic particles, dispersion medium, pigment, and silane coupling agent in the amounts (unit: parts by mass) shown in Table 2, kneaded them for 2 minutes at a revolution speed of 2000 rpm using a planetary mixer (manufactured by Shinki, "ARE-310" by Awatori Rentaro), then performed ink return, and further kneaded them for 2 minutes at a revolution speed of 2000 rpm using a planetary mixer to obtain a composition.

[0072] [Measurement of viscosity] The viscosities of the compositions of Example 3 and Comparative Examples 2 to 4 were measured under the following conditions using a rheometer (manufactured by Anton Paar, MCR92). The measurement results are shown in Table 2. In Table 2, V 0.1 , V 1.0 , and V 10.0 are the shear rates of 0.1 s -1, 1.0 s -1 , and 10.0 s -1 means the viscosity at that time. <Condition> · Measurement mode: Rotation · Temperature: 30 °C · Measuring jig: Φ25 parallel plate · Gap: 1 mm · Shear rate: 0.1 s -1 , 1.0 s -1 , 10.0 s -1

[0073] [Measurement of Thermal Conductivity] Using a thermal resistance measuring device (DynTIM, manufactured by Mentor Graphics), the thermal resistance values at each thickness of the compositions obtained in Example 3 and Comparative Examples 2 to 4 were measured under the following conditions. The relationship between the measured thermal resistance value and the thickness was approximated by a straight line, and the heat transfer rate was calculated from the slope of the obtained straight line and the area of the measurement part. The measurement results of the thermal conductivity are shown in Table 2. <Condition> · Cold plate temperature: 25 °C · Measurement mode: Pressure control mode of Type 2 "Visco-elastic solids" (pressure: about 4 kPa) · Thickness: 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm

[0074]

Table 2

Claims

Claim 1 A composition containing inorganic particles, wherein the inorganic particles are boron nitride particles having a maximum length of 100 μm or more and an aspect ratio of 1.5 or more and 12.0 or less, particles other than the boron nitride particles, and contain, the boron nitride particles have an outer shell portion formed of boron nitride and a hollow portion surrounded by the outer shell portion, the hollow portion is formed along the longitudinal direction of the boron nitride particles, and the average particle diameter of the particles other than the boron nitride particles is 0.1 μm or more and 200 μm or less. A composition. Claim 2 The composition according to claim 1, wherein the content of the boron nitride particles is 0.5 to 10% by volume based on the total volume of the inorganic particles. Claim 3 The composition according to claim 1 or 2, further containing a resin. Claim 4 At 30°C and a shear rate of 10.0 s －１ The composition according to any one of claims 1 to 3, having a viscosity of 1000 Pa·s or less at Claim 5 The composition according to any one of claims 1 to 4, which is for grease.

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