Vapor-phase alumina fine particles, resin composition containing vapor-phase alumina fine particles, and method for producing vapor-phase alumina fine particles

Abstract

To provide alumina fine particles which can suppress an increase in viscosity even when added to a base material such as a resin so that the base material such as a resin can be highly filled.SOLUTION: Gas-phase method alumina fine particles have a BET specific surface area of 20 m2 / g to 200 m2 / g and a bulk density of 50 g / L to 600 g / L.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to vapor-phase alumina fine particles that can be highly filled into a substrate such as a resin, a resin composition containing vapor-phase alumina fine particles, and a method for producing vapor-phase alumina fine particles. In particular, the present invention relates to vapor-phase alumina fine particles that can be highly filled into a substrate such as a resin used as a heat dissipation material, a resin composition containing vapor-phase alumina fine particles, and a method for producing vapor-phase alumina fine particles. [Background technology]

[0002] With the increasing sophistication of electrical and electronic equipment, the amount of heat generated by modules, electronic components, and other components installed in these devices is also increasing. Since high temperatures can impair normal operation of modules, electronic components, and other heat-generating elements, efficiently cooling these elements is crucial. To effectively cool these elements, it is essential to efficiently transfer heat from the heat-generating elements to heat exchange means such as heat sinks and metal components.

[0003] For example, to improve the thermal conductivity of a resin composition, an inorganic filler with excellent thermal conductivity may be added. Therefore, it has been proposed to (a) supply 100 parts by weight of gel, (b) combine the gel with 150 to 400 parts by weight of α-alumina having a particle size of at least 74 μm (at least 10% by weight), to form a gel-α-alumina mixture, and (c) mix the mixture to obtain a thermally conductive suitable composition (Patent Document 1). In Patent Document 1, the gel and α-alumina mixture is mixed at a specific energy input of at least 10 joules / g.

[0004] Patent Document 1 proposes obtaining an α-alumina composition with high thermal conductivity while maintaining high compatibility by mixing a mixture of α-alumina and a gel substance (or a precursor or precursor component of these components) while introducing a predetermined minimum mechanical energy into the mixture. Furthermore, Patent Document 1 states that even with a large amount of α-alumina filling, it is possible to achieve the amount of α-alumina necessary to achieve excellent thermal conductivity while preventing a decrease in the elongation and flexibility of the α-alumina-filled material.

[0005] However, Patent Document 1 uses α-alumina with a particle size of at least 74 μm as the inorganic filler, which means that the particle size of the α-alumina is large. On the other hand, if the particle size of the inorganic filler is large, the distance between the inorganic filler particles packed into the substrate becomes longer. Also, the larger the particle size of the inorganic filler, the more difficult it becomes to close-pack the inorganic filler into the substrate such as resin. Therefore, in terms of the distance between inorganic filler particles and close-packing of inorganic filler, a smaller particle size of inorganic filler is preferable for high-density filling of the inorganic filler into the substrate. From the above, Patent Document 1 had room for improvement in terms of improving thermal conductivity.

[0006] On the other hand, reducing the particle size of inorganic fillers in order to shorten the distance between particles and improve close packing of inorganic fillers increases the viscosity of compositions in which inorganic fillers are added to a substrate such as a resin, making it difficult to achieve high packing of inorganic fillers. Therefore, it has been proposed to treat the surface of alumina with a silane coupling agent to achieve high packing of alumina into a substrate such as a resin (Patent Document 2).

[0007] However, in Patent Document 2, which uses alumina surface-treated with a silane coupling agent as a filler, the suppression of viscosity increase was still insufficient, and there was room for improvement in highly filling alumina into a substrate such as resin. [Prior art documents] [Patent Documents]

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] In view of the above circumstances, an object of the present invention is to provide alumina fine particles that can be highly filled in a base material such as a resin by suppressing an increase in viscosity even when added to the base material such as a resin.

Means for Solving the Problems

[0010] The gist of the configuration of the present invention is as follows. [1]Vapor-phase alumina fine particles having a BET specific surface area of 20 m , ,

[0010] ,

[0009] , / g or more and 200 m 2 / g or less and a bulk density of 50 g / L or more and 600 g / L or less. [2]The vapor-phase alumina fine particles according to [1], which are surface-treated with an organosilicon compound. <00001oo>[3]The vapor-phase alumina fine particles according to [2], having a carbon content of 0.1% by mass or more and 5.0% by mass or less. [4]The vapor-phase alumina fine particles according to [2] or [3], wherein the vapor-phase alumina fine particles are surface-treated with 1.0 part by mass or more and 30 parts by mass or less of the organosilicon compound with respect to 100 parts by mass of the vapor-phase alumina fine particles. [5]The organosilicon compound is represented by the following general formula (1) (1)R 1 n SiR 2 (4-n) (In the formula, R 1 represents a hydrocarbon group having 1 to 18 carbon atoms, and R 2represents a hydrocarbon group having 1 to 18 carbon atoms, a chlorine atom, a hydroxy group or an alkoxy group having 1 to 3 carbon atoms, and n represents an integer of 1 to 3.) The organosilicon compound represented by, hexamethyldisilazane and / or silicone oil. The gas-phase method alumina fine particles according to any one of [2] to [4]. [6] The gas-phase method alumina fine particles according to any one of [1] to [5], having an average primary particle diameter of 7.0 nm or more and 50 nm or less. [7] The gas-phase method alumina fine particles according to any one of [1] to [6], which are used as a filler for a resin material. [8] The gas-phase method alumina fine particles according to [7], wherein the resin material is a heat dissipation material. [9] A resin composition containing the gas-phase method alumina fine particles according to any one of [1] to [8].

[10] An alumina raw material is introduced into a flame and subjected to a gas-phase decomposition method to obtain gas-phase method alumina fine particles having a BET specific surface area of 20 m 2 / g or more and 200 m 2 / g or less, a gas-phase method alumina fine particle preparation step, and An organosilicon compound supply step of applying an organosilicon compound to the surface of the gas-phase method alumina fine particles, and A pulverization step of pulverizing the gas-phase method alumina fine particles to which the organosilicon compound has been applied with a pulverizer, and including, having a BET specific surface area of 20 m 2 / g or more and 200 m 2 / g or less, and a bulk density of 50 g / L or more and 600 g / L or less. A method for producing gas-phase method alumina fine particles.

[11] The method for producing gas-phase method alumina fine particles according to [1], wherein the pulverizer is a ball mill.

[0011] In the above aspect, the "BET specific surface area" means the BET specific surface area of the gas-phase method alumina fine particles before being surface-treated with an organosilicon compound in the case of the gas-phase method alumina fine particles surface-treated with an organosilicon compound.

[0012] In the above embodiment, "bulk density" refers to the density (g / L) calculated from the volume (L) and mass (g) of the alumina fine particles measured 2 minutes after gently placing a fixed amount of alumina fine particles into a measuring container of a predetermined capacity on a balance. [Effects of the Invention]

[0013] According to the gas-phase alumina fine particles of the present invention, the BET specific surface area is 20 m². 2 / g or more 200m 2 Because the amount is less than / g and the bulk density is between 50 g / L and 600 g / L, the increase in viscosity of the substrate, such as a resin, can be suppressed even when the gas-phase alumina fine particles of the present invention are added to the substrate, such as a resin, and the gas-phase alumina fine particles of the present invention can be highly packed into the substrate. Therefore, according to the embodiment of the gas-phase alumina fine particles of the present invention, for example, when the substrate, such as a resin, is used as a heat dissipation material, excellent thermal conductivity can be imparted to the substrate.

[0014] According to an embodiment of the gas-phase alumina fine particles of the present invention, surface treatment with an organosilicon compound can further suppress the increase in viscosity of a substrate such as a resin, and can further improve the amount of filling into the substrate such as a resin.

[0015] According to an embodiment of the gas-phase alumina fine particles of the present invention, by having a carbon content of 0.1% by mass or more and 5.0% by mass or less, the increase in viscosity of the substrate such as a resin can be suppressed even more reliably, and the amount of filling into the substrate such as a resin can be improved even more reliably.

[0016] According to an embodiment of the vapor-phase alumina fine particles of the present invention, by having an average primary particle diameter of 7.0 nm or more and 50 nm or less, it is possible to reliably suppress the increase in viscosity of a substrate such as a resin, shorten the distance between vapor-phase alumina fine particles, and improve the close packing of vapor-phase alumina fine particles in a substrate such as a resin. Therefore, for example, when a substrate such as a resin is used as a heat dissipation material, it is possible to impart even better thermal conductivity to the substrate such as a resin.

[0017] The present invention provides a method for producing vapor-phase alumina fine particles, which includes a crushing step in which vapor-phase alumina fine particles treated with an organosilicon compound are crushed in a pulverizer. This makes it possible to suppress the increase in viscosity of a substrate such as a resin even when vapor-phase alumina fine particles are added to a substrate such as a resin, and to produce vapor-phase alumina fine particles that can be highly packed into a substrate such as a resin.

[0018] According to the gas-phase method for producing alumina fine particles of the present invention, by using a ball mill as the pulverizer, it is possible to produce gas-phase alumina fine particles that can more reliably suppress the increase in viscosity of a substrate such as a resin, and more reliably improve the amount of filling into the substrate such as a resin. [Best Mode for Carrying Out the Invention]

[0019] First, the vapor-phase alumina fine particles of the present invention will be described in detail below. The vapor-phase alumina fine particles of the present invention have a BET specific surface area of ​​20 m². 2 / g or more 200m 2 The weight is less than or equal to / g, and the bulk density is between 50 g / L and 600 g / L. Gas-phase alumina fine particles are alumina fine particles manufactured by the gas-phase method, i.e., by flame hydrolysis. Gas-phase alumina fine particles have hydroxyl groups or hydrophobic functional groups on their surface.

[0020] The above-mentioned vapor-phase alumina fine particles can suppress the increase in viscosity of a substrate such as a resin when added to such a substrate, and can be densely packed into such a substrate. Therefore, the vapor-phase alumina fine particles of the present invention can impart excellent thermal conductivity to a substrate such as a resin when the substrate is used as a heat dissipation material.

[0021] The BET specific surface area of ​​gas-phase alumina fine particles is 20 m². 2 / g or more 200m 2 While there are no particular limitations within the range of less than / g, the lower limit is 40m, in order to more reliably and effectively fill a substrate such as resin with gas-phase alumina fine particles. 2 / g is preferred, 50m 2 / g is more preferable, 60m2 / g is particularly preferred. On the other hand, the upper limit of the BET specific surface area of ​​gas-phase alumina fine particles is 180m, in order to more reliably suppress the increase in viscosity of the substrate such as resin. 2 / g is preferred, 160m 2 / g is more preferable, 140m 2 / g is particularly preferred.

[0022] The bulk density of vapor-phase alumina fine particles is not particularly limited as long as it is within the range of 50 g / L to 600 g / L, but the lower limit is preferably 90 g / L, more preferably 120 g / L, and particularly preferably 150 g / L, from the viewpoint of more reliably suppressing the increase in viscosity of the base material such as resin. On the other hand, the upper limit of the bulk density of vapor-phase alumina fine particles is preferably 570 g / L, more preferably 540 g / L, and particularly preferably 520 g / L, from the viewpoint of the production efficiency of vapor-phase alumina fine particles.

[0023] The average primary particle diameter of vapor-phase alumina fine particles is not particularly limited, but its lower limit is preferably 7.0 nm, more preferably 8.0 nm, and especially preferably 9.0 nm, from the standpoint of reliably suppressing the viscosity increase of the substrate such as resin and achieving high packing of vapor-phase alumina fine particles. On the other hand, the upper limit of the average primary particle diameter of vapor-phase alumina fine particles is preferably 50 nm, more preferably 40 nm, and especially preferably 30 nm, from the standpoint of shortening the distance between vapor-phase alumina fine particles and improving the close packing of vapor-phase alumina fine particles in the substrate such as resin, for example, when the substrate such as resin is used as a heat dissipation material, it is possible to impart even better thermal conductivity to the substrate such as resin.

[0024] Furthermore, as will be explained later, the average primary particle size of gas-phase alumina fine particles refers to the average primary particle size of gas-phase alumina fine particles that have been surface-treated with an organosilicon compound, in cases where the gas-phase alumina fine particles have been surface-treated with an organosilicon compound.

[0025] The vapor-phase alumina nanoparticles of the present invention may be surface-treated with an organosilicon compound. That is, the vapor-phase alumina nanoparticles may be vapor-phase alumina nanoparticles whose surface has been modified with an organosilicon compound (hereinafter sometimes referred to as "organosilicon compound-modified vapor-phase alumina nanoparticles"). In this case, the organosilicon compound functions as a surface modifier for the vapor-phase alumina nanoparticles. By modifying the surface of the vapor-phase alumina nanoparticles with an organosilicon compound, the increase in viscosity of the substrate, such as a resin, to which the vapor-phase alumina nanoparticles are added can be further suppressed, and the amount of vapor-phase alumina nanoparticles filling into the substrate can be further improved. By further improving the amount of vapor-phase alumina nanoparticles filling into the substrate, such as a resin, it is possible to impart even better thermal conductivity to the substrate, such as a resin, when the substrate is used as a heat dissipation material.

[0026] One aspect of surface modification of vapor-phase alumina nanoparticles is that, for example, a portion or the entire surface of the vapor-phase alumina nanoparticles may be coated with a layer of organosilicon compound. In this case, among the organosilicon compound-modified vapor-phase alumina nanoparticles, the vapor-phase alumina nanoparticles form the core particles and the organosilicon compound forms the shell, thus the organosilicon compound-modified vapor-phase alumina nanoparticles have a core-shell structure.

[0027] Examples of organosilicon compounds that function as surface modifiers include the following general formula (1): R 1 n SiR 2 (4-n) (1) (In the formula, R 1 R represents a hydrocarbon group with 1 to 18 carbon atoms. 2 R represents a hydrocarbon group having 1 to 18 carbon atoms, a chlorine atom, a hydroxyl group, or an alkoxy group having 1 to 3 carbon atoms, preferably an alkoxy group having 1 to 2 carbon atoms, and n represents an integer from 1 to 3. Examples include organosilicon compounds represented by ). In general formula (1), R 1 It is an alkyl group consisting only of carbon and hydrogen, and does not contain heteroatoms such as nitrogen, oxygen, or phosphorus. 2When the group is an alkoxy group, the number of carbon atoms in the alkoxy group is between 1 and 3. If the number of carbon atoms in the alkoxy group is 4 or more, the reactivity decreases, requiring a long time for surface modification. Furthermore, organosilicon compounds with alkoxy groups having 4 or more carbon atoms are generally difficult to obtain industrially.

[0028] Furthermore, examples of organosilicon compounds that function as surface modifiers include hexamethyldisilazane.

[0029] Furthermore, an example of an organosilicon compound that functions as a surface modifier is silicone oil. The kinematic viscosity of silicone oil at 25°C is, for example, 0.65 mm. 2 / s~10000mm 2 One example is / s. When performing uniform surface modification on silicone oil, it is necessary to dissolve the silicone oil in a suitable solvent, and the kinematic viscosity of the silicone oil is 10,000 mm². 2 When the solvent rate exceeds 1 / s, a large excess of solvent is required for surface modification. This leads to increased process complexity and costs, as well as problems such as the tendency for agglomeration of gas-phase alumina fine particles to occur when the solvent is evaporated.

[0030] In the present invention, the method for reacting the gas-phase alumina fine particles with a surface modifier is not particularly limited, and as a general example, an ordinary surface modification method can be used. Specific examples include a method of evaporating the surface modifier and bringing it into contact with the gas-phase alumina fine particles, a method of spraying the surface modifier onto the surface of the gas-phase alumina fine particles by spraying while the gas-phase alumina fine particles are flowing (dry contact method), and a method of dissolving the surface modifier in a predetermined solvent and dispersing the gas-phase alumina fine particles in the solvent containing the dissolved surface modifier. Of these, the dry contact method is preferred in that it prevents aggregation of the gas-phase alumina fine particles and allows for uniform treatment.

[0031] The carbon content of the organosilicon compound modified vapor-phase alumina fine particles is not particularly limited, but the lower limit is preferably 0.1% by mass, and particularly preferably 0.3% by mass, in order to further suppress the increase in viscosity of the substrate such as resin and to further improve the amount of filling into the substrate such as resin. On the other hand, the upper limit of the carbon content of the organosilicon compound modified vapor-phase alumina fine particles is preferably 5.0% by mass, and particularly preferably 4.5% by mass, in order to prevent moisture from being adsorbed onto the unreacted surface modifier or contamination of other components by the unreacted surface modifier due to the presence of a large amount of unreacted surface modifier on the surface of the vapor-phase alumina fine particles caused by the presence of an excess of surface modifier.

[0032] The amount of organosilicon compound used as a surface modifier for surface treatment of gas-phase alumina fine particles is not particularly limited, but the lower limit is preferably 1.0 part by mass, more preferably 2.0 parts by mass, and particularly preferably 3.0 parts by mass per 100 parts by mass of gas-phase alumina fine particles that have not been surface-treated with an organosilicon compound, in order to further suppress the increase in viscosity of the substrate such as resin and to further improve the amount of filling into the substrate such as resin. On the other hand, the upper limit of the amount of organosilicon compound used is preferably 30 parts by mass, more preferably 25 parts by mass, and particularly preferably 20 parts by mass per 100 parts by mass of gas-phase alumina fine particles that have not been surface-treated with an organosilicon compound, in order to prevent the adsorption of moisture, etc.

[0033] Next, the present invention has a BET specific surface area of ​​20 m². 2 / g or more 200m 2 This invention describes a method for producing gas-phase alumina fine particles having a BET specific surface area of ​​20 m² or less and a bulk density of 50 g / L to 600 g / L. 2 / g or more 200m 2The method includes: a gas-phase alumina fine particle preparation step for obtaining gas-phase alumina fine particles with a particle size of 1 / g or less; an organosilicon compound supply step for applying an organosilicon compound to the surface of the gas-phase alumina fine particles; and a crushing step for crushing the gas-phase alumina fine particles to which the organosilicon compound has been applied using a crusher.

[0034] By including a crushing step in which gas-phase alumina fine particles treated with an organosilicon compound are crushed in a pulverizer, it is possible to suppress the increase in viscosity of a substrate such as a resin even when gas-phase alumina fine particles are added to a substrate such as a resin, and to produce gas-phase alumina fine particles that can be highly packed into a substrate such as a resin, i.e., gas-phase alumina fine particles having a bulk density of 50 g / L or more and 600 g / L or less.

[0035] In the vapor phase alumina fine particle preparation process, the BET specific surface area is 20 m². 2 / g or more 200m 2 Gas-phase alumina fine particles with a density of less than / g can be obtained, for example, by adjusting reaction conditions such as flame temperature, hydrogen or oxygen ratio, amount of aluminum trichloride, residual time in the flame, and length of the solidification zone.

[0036] In the organosilicon compound supply process, methods for applying the organosilicon compound to the surface of gas-phase alumina fine particles include: evaporating the organosilicon compound and bringing it into contact with the gas-phase alumina fine particles; spraying the organosilicon compound onto the surface of the gas-phase alumina fine particles by spraying or the like while the gas-phase alumina fine particles are flowing under an inert gas atmosphere and then heating them (dry contact method); and dissolving the organosilicon compound in a predetermined solvent and dispersing the gas-phase alumina fine particles in the solvent containing the dissolved organosilicon compound. Of these, the dry contact method is preferred in that it prevents aggregation of the gas-phase alumina fine particles and ensures uniform processing.

[0037] Examples of inert gases used in the dry contact process include oxygen-free gases such as nitrogen, helium, and argon. Examples of heating conditions in the dry contact process include a heat treatment temperature of 80°C to 370°C and a heating time of 15 minutes to 350 minutes.

[0038] In the crushing process, examples of crushers used include ball mills (e.g., rolling ball mills), roller mills, planetary mills, and agitation mills. Of these, ball mills are preferred because they can produce gas-phase alumina fine particles that can more reliably suppress the increase in viscosity of the base material such as resin and more reliably improve the amount of filling into the base material such as resin, that is, they can easily produce gas-phase alumina fine particles with a bulk density of 50 g / L to 600 g / L. Therefore, gas-phase alumina fine particles obtained by crushing with a ball mill are preferred as the gas-phase alumina fine particles of the present invention.

[0039] Regarding the crushing conditions in the ball mill, for example, the rotation speed of the container containing the gas-phase alumina fine particles to be crushed is preferably 30 rpm to 200 rpm, more preferably 50 rpm to 100 rpm, and particularly preferably 60 rpm to 80 rpm, in order to reliably adjust the bulk density of the gas-phase alumina fine particles to a range of 50 g / L to 600 g / L. In addition, the diameter of the balls used in the ball mill is preferably 5 mm to 30 mm, more preferably 7 mm to 20 mm, and particularly preferably 10 mm to 15 mm, in order to reliably adjust the bulk density of the gas-phase alumina fine particles to a range of 50 g / L to 600 g / L.

[0040] The vapor-phase alumina fine particles of the present invention can be used, for example, as a filler for a substrate such as a resin material.

[0041] Furthermore, applications for the resin material and other substrates include, for example, heat dissipation materials, building materials, and materials for electronic components. For example, by adding the vapor-phase alumina fine particles of the present invention as a filler to a heat dissipation material, the heat dissipation material is given excellent thermal conductivity. Therefore, by thermally connecting the heat dissipation material to which the vapor-phase alumina fine particles of the present invention are added to a heat-generating element such as a module or electronic component, the heat dissipation material can receive heat from the heat-generating element and efficiently transfer heat to a heat exchange means such as a heat sink or metal member, thereby effectively cooling the heat-generating element such as the module or electronic component.

[0042] Examples of resin materials to which vapor-phase alumina fine particles can be added include silicone resins, epoxy resins, and polyimide resins.

[0043] The amount of vapor-phase alumina fine particles added to the resin material can be appropriately selected depending on the usage conditions of the resin material, for example, 1.0 part by mass or more and 50 parts by mass or less per 100 parts by mass of the resin material is preferred, and 10 parts by mass or more and 30 parts by mass or less is particularly preferred.

[0044] As a method for preparing a resin composition containing vapor-phase alumina fine particles, for example, the vapor-phase alumina fine particles of the present invention can be added to a resin in a predetermined proportion, and then kneaded or mixed at room temperature (e.g., 10°C to 30°C) using a mixing and kneading means such as a three-roll mixer or kneader, or a stirring and mixing means such as a rotational mixer, super mixer, planetary mixer, or Trimix. [Examples]

[0045] Next, embodiments of the present invention will be described, but the present invention is not limited to the embodiments described herein unless it exceeds the spirit of the invention.

[0046] <Example 1> BET specific surface area 100m² manufactured by the gas phase method 2100 parts by mass of vapor-phase alumina fine powder (manufactured by Evonik Industries, trade name: "AEROXIDE (trademark) Alu C") was placed in a reaction vessel. Under a nitrogen atmosphere, 15 parts by mass of a silane coupling agent (manufactured by Evonik Industries, trade name: "Dynasylan (trademark) IBTMO", compound name: "isobutyltrimethoxysilane") was sprayed while stirring. The mixture was heated and stirred at 200°C for 120 minutes, then cooled to obtain vapor-phase alumina fine particles modified with organosilicon compounds. The carbon content of the obtained vapor-phase alumina fine particles was 3.1% by mass, which is greater than 0.1% by mass. The average primary particle size of the vapor-phase alumina fine particles was 13 nm.

[0047] The organosilicon compound modified vapor-phase alumina fine particles obtained as described above were crushed in a ball mill (rotation speed: 65 rpm, ball size: 14 mmφ) for 30 minutes to obtain organosilicon compound modified vapor-phase alumina fine particles with a bulk density of 96 g / L.

[0048] A sample of a resin composition containing silicone resin and organic silicon compound-modified vapor-phase alumina fine particles was prepared by filling 100 parts by mass of silicone resin (Momentive Corporation: TSE3062) with 20 parts by mass of the organosilicon compound-modified vapor-phase alumina fine particles prepared as described above. The mixture was then stirred and dispersed (2000 rpm, 2 minutes) and defoamed (2200 rpm, 1 minute) using a rotary-orbit mixer (THINKY Corporation: Awatori Rentaro ARE-310) to prepare a sample of a resin composition in which the silicone resin was filled with organosilicon compound-modified vapor-phase alumina fine particles.

[0049] <Example 2> Except for changing the crushing time in the ball mill to 180 minutes, organosilicon compound modified vapor-phase alumina fine particles were obtained in the same manner as in Example 1, and a resin composition sample was prepared. The carbon content of the obtained organosilicon compound modified vapor-phase alumina fine particles was 3.1% by mass, and the average primary particle size of the organosilicon compound modified vapor-phase alumina fine particles was 13 nm. The bulk density of the organosilicon compound modified vapor-phase alumina fine particles was 199 g / L.

[0050] <Example 3> Except for changing the crushing time in the ball mill to 300 minutes, organosilicon compound modified vapor-phase alumina fine particles were obtained in the same manner as in Example 1, and a resin composition sample was prepared. The carbon content of the obtained organosilicon compound modified vapor-phase alumina fine particles was 3.1% by mass, and the average primary particle size of the organosilicon compound modified vapor-phase alumina fine particles was 13 nm. The bulk density of the organosilicon compound modified vapor-phase alumina fine particles was 509 g / L.

[0051] <Example 4> Alumina fine powder produced by gas phase method, BET specific surface area 130 m² 2 Except for changing the alumina fine powder (manufactured by Evonik Industries, trade name: "AEROXIDE (trademark registered) Alu 130") in a weight of / g and changing the crushing time in the ball mill to 300 minutes, organosilicon compound modified vapor-phase alumina fine particles were obtained in the same manner as in Example 1, and a resin composition sample was prepared. The carbon content of the obtained organosilicon compound modified vapor-phase alumina fine particles was 4.0% by mass, and the average primary particle size of the organosilicon compound modified vapor-phase alumina fine particles was 17 nm. The bulk density of the organosilicon compound modified vapor-phase alumina fine particles was 405 g / L.

[0052] <Example 5> Except for replacing the silane coupling agent isobutyltrimethoxysilane with 15 parts by mass of hexamethyldisilazane (HMDS) and changing the crushing treatment time in the ball mill to 300 minutes, organosilicon compound modified vapor-phase alumina fine particles were obtained in the same manner as in Example 1, and a resin composition sample was prepared. The carbon content of the obtained organosilicon compound modified vapor-phase alumina fine particles was 1.5% by mass, and the average primary particle size of the organosilicon compound modified vapor-phase alumina fine particles was 13 nm. The bulk density of the organosilicon compound modified vapor-phase alumina fine particles was 495 g / L.

[0053] <Comparative Example 1> BET with a specific surface area of ​​100 m², manufactured by a gas-phase method without modification with organosilicon compounds or crushing treatment. 220 parts by mass of vapor-phase alumina fine powder (manufactured by Evonik Industries, trade name: "AEROXIDE (trademark registered) Alu C", hereinafter referred to as "untreated vapor-phase alumina fine powder") was filled into 100 parts by mass of silicone resin (manufactured by Momentive: TSE3062), and the mixture was stirred and dispersed (2000 rpm, 2 minutes) and defoamed (2200 rpm, 1 minute) using a rotary-orbit mixer (manufactured by THINKY: Awatori Rentaro ARE-310) to prepare a resin composition sample in which the silicone resin was filled with the above untreated vapor-phase alumina fine particles. The average primary particle size of the untreated vapor-phase alumina fine powder was 13 nm and the bulk density was 40 g / L.

[0054] <Comparative Example 2> A resin composition sample was prepared using the same procedure as in Example 1, except that the organosilicon compound modified vapor-phase alumina fine particles were not subjected to crushing treatment. The carbon content of the obtained organosilicon compound modified vapor-phase alumina fine particles was 3.1% by mass, and the average primary particle size of the organosilicon compound modified vapor-phase alumina fine particles was 13 nm. The bulk density of the organosilicon compound modified vapor-phase alumina fine particles was 41 g / L.

[0055] <Comparative Example 3> BET specific surface area 4.6m 2 20 parts by mass of alumina microparticles (Sumitomo Chemical Co., Ltd., product name: [AA-04]) weighing 1 / g were filled into 100 parts by mass of silicone resin (Momentive Corporation: TSE3062). The mixture was then stirred and dispersed (2000 rpm, 2 minutes) and defoamed (2200 rpm, 1 minute) using a rotational mixer (THINKY Corporation: Awatori Rentaro ARE-310) to prepare a resin composition sample in which the above alumina microparticles were filled into the silicone resin. The average primary particle size of the above alumina fine powder was 470 nm and the bulk density was 673 g / L.

[0056] The measurement methods for each item are as follows:

[0057] [Method for measuring the bulk density of alumina microparticles] Using an electronic balance, a fixed amount of alumina microparticles was gently placed into a graduated cylinder, and after 2 minutes, the volume (L) and mass (g) of the alumina microparticles were measured. From these measurements, the bulk density (g / L) was calculated.

[0058] [Method for measuring the carbon content of alumina microparticles] The following measurements were taken using a carbon analyzer (manufactured by Sumika Analysis Center Co., Ltd., product name: SUMIGRAPH NC-22). Detector conditions: "INJ / DET" = 100°C, "COL" = 70°C Gas flow rate: O2 = 350 ml / min, He = 80 ml / min

[0059] [Method for measuring the average primary particle size of alumina microparticles] The results were obtained by analyzing images taken with a transmission electron microscope. Specifically, 50 images were taken with different fields of view, and the average primary particle size of 2500 alumina microparticles was analyzed using image analysis and calculated as the average by number of particles.

[0060] [Method for measuring the viscosity of resin composition samples] For resin composition samples immediately after preparation and resin composition samples one week after preparation, the following measurements were taken using a rheometer (Anton Paar: MCR-300) at a temperature of 23°C for 0.1 seconds. -1 ~100s -1 0.1s when measuring steady flow viscosity at shear rate -1 The viscosity was measured as a constant value. In addition, the relative viscosity of the resin composition sample immediately after preparation was evaluated compared to Comparative Example 1.

[0061] Table 1 below shows the BET specific surface area, bulk density, type of surface treatment agent, and viscosity (viscosity immediately after preparation), relative viscosity, and viscosity after one week of the resin composition samples for Examples 1-5 and Comparative Examples 1-3 described above.

[0062] [Table 1]

[0063] From Table 1 above, the BET specific surface area is 20m². 2 / g or more 200m 2 In resin composition samples filled with gas-phase alumina microparticles from Examples 1-5, which have a bulk density of 50 g / L to 600 g / L and are surface-treated with an organosilicon compound, viscosity increase was suppressed both immediately after preparation and one week later. Therefore, it was found that gas-phase alumina microparticles from Examples 1-5 can be highly packed into substrates such as resins. In particular, in Examples 2-5, which have a bulk density of 199 g / L or more, viscosity increase was suppressed even more effectively, and in Examples 3-5, which have a bulk density of 405 g / L or more, an even better viscosity increase suppression effect was obtained.

[0064] On the other hand, in Comparative Example 1, where untreated vapor-phase alumina fine powder was filled into the resin, the bulk density of the vapor-phase alumina fine particles was 40 g / L, and the viscosity increased significantly immediately after the preparation of the resin composition sample. Furthermore, in Comparative Example 1, the viscosity increased even further one week after the preparation of the resin composition sample, making viscosity measurement impossible. In Comparative Example 2, where the organosilicon compound modified vapor-phase alumina fine particles were not crushed, the bulk density was 41 g / L, and the viscosity increased both immediately after the preparation of the resin composition sample and one week later, although not to the same extent as in Comparative Example 1. In Comparative Example 3, where the bulk density was 673 g / L, the viscosity also increased both immediately after the preparation of the resin composition sample and one week later, although not to the same extent as in Comparative Example 1. [Industrial applicability]

[0065] The vapor-phase alumina fine particles of the present invention can suppress the increase in viscosity when added to a substrate such as a resin, allowing for high-density filling of the substrate. Therefore, they can be applied in a wide range of fields, and are particularly valuable in fields such as fillers for heat dissipation materials.

Claims

1. A resin composition containing vapor-phase alumina fine particles, The resin composition contains a resin material selected from the group consisting of silicone resin, epoxy resin, and polyimide resin. The aforementioned gas-phase alumina fine particles are The surface is treated with an organosilicon compound. The gas-phase alumina fine particles before surface treatment with the organosilicon compound have a BET specific surface area of ​​20 m² / g or more and 200 m² / g or less, and The bulk density of the vapor-phase alumina fine particles after surface treatment with the organosilicon compound is 90 g / L or more and 600 g / L or less. The aforementioned resin composition.

2. The resin composition according to claim 1, wherein the carbon content of the gas-phase alumina fine particles is 0.1% by mass or more and 5.0% by mass or less.

3. The resin composition according to claim 1 or 2, wherein the vapor-phase alumina fine particles are surface-treated with 1.0 part by mass or more and 30 parts by mass or less of the organosilicon compound, relative to 100 parts by mass of the vapor-phase alumina fine particles before surface treatment with the organosilicon compound.

4. The organosilicon compound is defined by the following general formula (1) (1)R １ ｎ SiR ２ （４－ｎ） (In the formula, R １ R represents a hydrocarbon group having 1 to 18 carbon atoms. ２ The resin composition according to any one of claims 1 to 3, wherein n is an organosilicon compound represented by ), hexamethyldisilazane, and / or silicone oil.

5. The resin composition according to any one of claims 1 to 4, wherein the average primary particle size of the vapor-phase alumina fine particles is 7.0 nm or more and 50 nm or less.

6. Alumina raw material is introduced into a flame and subjected to gas-phase decomposition, resulting in a BET specific surface area of ​​20 m². ２ / g or more 200m ２ A process for preparing gas-phase alumina fine particles to obtain gas-phase alumina fine particles with a density of less than / g, An organosilicon compound supply step is performed by applying an organosilicon compound to the surface of the aforementioned gas-phase alumina fine particles, A crushing step is performed in which the gas-phase alumina fine particles to which the organosilicon compound has been applied are crushed in a pulverizer to obtain a bulk density of 90 g / L or more and 600 g / L or less. A method for producing alumina fine particles using a gas phase method, including the method described above.

7. The method for producing alumina fine particles by gas phase according to claim 6, wherein the pulverizer is a ball mill.

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