JP2019034864A - Aluminum nitride-based filler - Google Patents

Abstract

To provide an aluminum nitride-based filler having high water resistance, non-catalytic poisoning property, high resin mixing capacity and the like.SOLUTION: The aluminum nitride filler in which an oxide film is formed on a surface of an aluminum nitride particle according to the present invention has a value of [A/B] of 1 to 29.9, where A (mm/g) is a measured value of a specific surface area measured by BET method and B (m/g) is a calculated value of the specific surface area calculated assuming that its shape is spherical.SELECTED DRAWING: None

Description

  The present invention relates to a novel aluminum nitride filler. More specifically, the present invention relates to an aluminum nitride-based filler that is excellent in water resistance as well as filling properties for a resin.

  Aluminum nitride is known as a material excellent in thermal conductivity, electrical insulation and the like. In order to utilize such characteristics, aluminum nitride is used in various applications. In particular, it has attracted attention as a heat conductive filler for increasing the heat conductivity of a resin. For example, resin-made electronic parts (resin products) such as semiconductor substrates are required to take measures against heat generated by electronic parts (heat dissipation means) more than ever with downsizing and higher integration of electronic devices. Yes. For this reason, various techniques for blending aluminum nitride as a filler in a resin have been proposed.

However, aluminum nitride inherently easily reacts with water. That is, it is known that aluminum nitride reacts with water to cause hydrolysis and generate ammonia as follows.
AlN + 3H ₂ O → Al (OH) ₃ + NH ₃ ↑

  Even in the case of aluminum nitride contained in the resin, there is a risk that the quality of the resin product may be deteriorated by reacting with moisture in the atmosphere and moisture in the resin.

  In addition, aluminum nitride may degrade the performance of the resin used for electronic components. For example, in silicone resins, a type of curing using a platinum catalyst is widely adopted. However, in such types of silicone resins, nitrogen contained in aluminum nitride becomes a catalyst poison, which may inhibit the curing of the silicone resin. is there.

  For this reason, attempts have been made to solve the above problems by subjecting the surface of aluminum nitride particles to surface treatment.

  For example, (a) applying a layer of silicate ester on an aluminum nitride-containing powder having aluminum nitride on at least a portion of its surface, wherein the silicate ester is a group consisting of alkyl and alkoxyalkyl groups And (b) the coated aluminum nitride-containing powder at a temperature of 350-1000 ° C., whereby the silicate ester reacts with the surface aluminum nitride, thereby forming a surface Moisture-proof aluminum nitride containing comprising heat treating for a time sufficient to cause a treated aluminum nitride-containing powder having a layer of Si-Al-O-N bonded to aluminum nitride A method for making a powder has been proposed (Patent Document 1).

  Further, at least selected from an organosilicon coupling agent, an organophosphoric coupling agent, and an organotitanium coupling agent containing a phosphate group in the molecule on an aluminum nitride powder having an aluminum oxide film or a phosphoric acid film on the surface. There is a method for producing an aluminum nitride powder having excellent water resistance, characterized in that one coupling agent is added and treated in an amount of 0.1 to 10 parts by mass per 100 parts by mass of the aluminum nitride powder (Patent Document 2).

  Furthermore, for example, water-resistant aluminum nitride containing 0.1 to 25% by weight of silicon carbide in aluminum nitride is known (Patent Document 3).

  In addition, for example, the powder is composed of composite particles in which a coating layer is formed on the surface of aluminum nitride particles, and (1) the coating layer includes Si, O, H, and an alkyl group, and (2) An aluminum nitride-based powder characterized in that the amount of organic carbon is 0.02 to 1.0% by weight has been proposed (Patent Document 4).

Special table flat 7-507760 JP-A-7-33415 JP-A-10-273306 JP 2006-290667 A

  However, even in these conventional techniques, an aluminum nitride filler having satisfactory water resistance or the like has not been obtained, and there is room for further improvement in that respect.

  Accordingly, a main object of the present invention is to provide an aluminum nitride filler that has high water resistance, non-catalytic toxicity, high filling property for resin, and the like.

  As a result of intensive studies in view of the problems of the prior art, the present inventor has found that the above object can be achieved by an aluminum nitride-based filler having a specific configuration, and has completed the present invention.

That is, the present invention relates to the following aluminum nitride filler.
1. A filler in which an oxide film is formed on the surface of aluminum nitride particles,
For the filler, the measured value of the specific surface area measured by the BET method is A (m ² / g), and the calculated value of the specific surface area calculated when the shape is spherical is B (m ² / g). In this case, the aluminum nitride filler is characterized in that the value of [A / B] is 1 to 29.9.
2. Item 2. The aluminum nitride filler according to Item 1, wherein the oxide film is at least one of silica and alumina.
3. Item 3. The aluminum nitride filler according to Item 1 or 2, wherein the average particle diameter D50 is 0.1 to 100 µm.
4). Item 4. The aluminum nitride filler according to any one of Items 1 to 3, wherein the oxide film is contained in an amount of 0.1 to 50 parts by mass with respect to 100 parts by mass of the aluminum nitride particles.
5. Item 5. A highly thermally conductive resin composition comprising the aluminum nitride filler according to any one of Items 1 to 4 and a resin component.

  ADVANTAGE OF THE INVENTION According to this invention, the aluminum nitride type filler which has high water resistance, non-catalytic toxicity, the high filling property with respect to resin, etc. can be provided.

In particular, the aluminum nitride filler of the present invention has specific physical properties by a specific manufacturing method. That is, when the measured value of the specific surface area measured by the BET method is A (m ² / g) and the calculated value of the specific surface area calculated when the shape is spherical is B (m ² / g), The value of [A / B] is within the range from 1 to a specific value. This means that the oxide film on the filler surface is formed in a smooth state with few fine irregularities, and the oxide film is formed relatively uniformly over the entire surface of the aluminum nitride particles. It also leads to. Therefore, by setting the [A / B] value within the above specific range, it is possible to obtain a higher filling property for the resin as well as high water resistance and non-catalytic toxicity.

  The filler having such characteristics can be suitably used as a filler in the resin composition. More specifically, it can be used as a filler that can impart high thermal conductivity (high heat dissipation) to the resin composition. Such a resin composition can be widely used, for example, for electronic materials / electronic parts, automobile parts, home appliances, paints / inks and the like.

1. Aluminum nitride filler The aluminum nitride filler of the present invention (the filler of the present invention) is a filler in which an oxide film is formed on the surface of aluminum nitride particles,
For the filler, the measured value of the specific surface area measured by the BET method is A (m ² / g), and the calculated value of the specific surface area calculated when the shape is spherical is B (m ² / g). The value of [A / B] is 1 to 29.9.

  The aluminum nitride particles are particles serving as the core of the filler of the present invention, and an oxide film (particularly an inorganic oxide film) is laminated on the surface thereof.

  Known or commercially available aluminum nitride particles can be used. It can also be prepared by a known production method. Therefore, for example, aluminum nitride particles (powder) obtained by a direct nitriding method, aluminum nitride particles (powder) obtained by a combustion synthesis method, aluminum nitride particles (powder) obtained by a reduction method, etc. may be used as appropriate. it can.

  The average particle diameter of the aluminum nitride particles (powder) is not limited, but it is particularly preferable that D50 when the volume distribution is measured with a laser diffraction particle size distribution meter is set within a range of 0.1 to 50 μm. . If the D50 of the aluminum nitride particles used as a raw material is less than 0.1 μm, uniform coating may be difficult. When the D50 is more than 100 μm, the specific surface area is small, so that the effect of improving the filling property tends to be difficult to obtain.

  The shape of the aluminum nitride particles is not particularly limited, and may be any shape such as a spherical shape, a scale shape, and an indefinite shape.

  The oxide coating is a surface layer that covers a part or all of the surface of the aluminum nitride particles, and it is desirable that the oxide coating covers substantially the entire surface of the aluminum nitride particles. By forming the oxide film, excellent water resistance, non-catalytic toxicity, filling property and the like can be obtained.

  As the oxide, various metal or non-metal oxides can be used. Examples thereof include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, cerium oxide and the like. These may be contained alone or in combination of two or more. Further, as described later, among the above oxides, oxides obtained by a sol-gel method can be preferably used.

  The amount of oxide film formed (coating amount) is not particularly limited as long as it can cover the entire surface of the aluminum nitride powder, and is usually 0.1 to 50 parts per 100 parts by mass of aluminum nitride particles. It is preferable to set it as about a mass part. The thickness of the surface layer may be in the range of, for example, about 1 to 200 nm, but is not particularly limited thereto.

  The average particle diameter D50 of the filler of the present invention is particularly preferably 0.1 to 100 μm, and more preferably 1 to 50 μm. When the D50 is less than 0.1 μm, the resin tends to aggregate and the amount of oil absorption increases, so that filling the resin tends to be difficult. When the above D50 exceeds 100 μm, excellent water resistance and non-catalytic toxicity effects can be obtained, but the effect of improving the filling property is hardly obtained.

BET specific surface area of the present invention the filler is not particularly limited as long as it satisfies the [A / B] values of the present invention, usually a 0.1 to 20 m ² / g approximately, in particular 0.5 to 10 m ² / g Of these, 0.5 to ⁵ m ² / g is more preferable.

In the filler of the present invention, the actual value of the specific surface area measured by the BET method is A (m ² / g), and the calculated value of the specific surface area when the shape is spherical is B (m ² / g). The value of [A / B] is from 1 to 29.9, particularly preferably from 1 to 19.9, more preferably from 1.5 to 10, of which 2 to 5 Most preferably. In the present invention, the value of [A / B] means that the lower the value in the above range, the smoother the surface of the filler of the present invention is, and it is an indicator that higher filling properties can be obtained for the resin. More specifically, the value of A is a numerical value influenced by the roughness of the surface and the size of the particle. By dividing the A value by the theoretical value B of the surface area in an ideally smooth state, the particle The degree of surface roughness can be estimated. That is, the filler having a value of [A / B] close to 1 can be filled in the resin more because the filler surface is smoother, and if the filler has the same filling amount, the resin This means that the viscosity of the composition can be kept lower.

The value B can be obtained by the calculation formula shown in Test Example 1 described later, but can also be automatically calculated by a system built in a commercially available particle size distribution measuring apparatus. For example, the value B can be calculated by using a particle size distribution measuring apparatus (trade name “MT3300EXII”, manufactured by Microtrack Bell Co., Ltd.) using a laser diffraction / scattering method. However, when the unit of the value of B is calculated as “m ² / ml” as in Test Example 1 described later, for example, it may be converted into “m ² / g” based on the specific gravity of the measurement sample. In this case, in the present invention, the specific gravity is a calculated value obtained from each theoretical density of aluminum nitride and oxide constituting the measurement sample (aluminum nitride filler).

2. Method for Producing Aluminum Nitride-Based Filler The filler of the present invention is not particularly limited as long as a predetermined metal oxide film can be formed on the surface of aluminum nitride particles as a core, but is preferably produced by a sol-gel method as described below.
That is, a) a first step of preparing a mixed solution by adding an alkoxide compound to a dispersion in which aluminum nitride particles are dispersed in a solvent; b) a step of hydrolyzing the alkoxide compound by adding an acid catalyst to the mixed solution. The filler of the present invention can be suitably produced by a method comprising two steps, c) a third step of adding a base catalyst to the mixed solution after hydrolysis, and d) a fourth step of drying the obtained reaction product. it can.

First Step In the first step, a mixed solution is prepared by adding an alkoxide compound to a dispersion in which aluminum nitride particles (powder) are dispersed in a solvent.

  The solvent used in the dispersion is not limited, but it is particularly preferable to use an aqueous solvent. As the aqueous solvent, at least one of water, a water-soluble organic solvent, and a mixed solvent thereof can be suitably used. Examples of the water-soluble organic solvent include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, t-butyl alcohol, n-butyl alcohol, isobutyl alcohol, ethyl cellosolve, butyl cellosolve, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether , Propylene glycol monopropyl ether, acetone and the like.

  The dispersion amount of the aluminum nitride particles in the dispersion can be appropriately set within a range of usually about 10 to 60% by weight, but is not limited thereto.

As an alkoxide compound, it can select suitably according to the metal seed | species (or cation seed | species) of a desired oxide film. That is, a metal alkoxide or a non-metal alkoxide represented by the general formula M (OR) _n (where M is a cation element, R is an alkyl group, and n is the oxidation number of the element) is preferably used. Can do. For example, when a silicon oxide (silica) film is formed as the oxide film, an alkoxide compound represented by Si (OR) ₄ can be preferably used. In the above general formula, M is not particularly limited, but Si, Zr, Ce, Al, or Ti is preferable. R is preferably an alkyl group having 1 to 10 carbon atoms.

  Specific examples of the alkoxide compound include tetraalkoxysilanes such as tetraethoxysilane, tetramethoxysilane and tetrapropoxysilane, tetraalkoxytitanium such as tetramethoxytitanium, tetraethoxytitanium and tetrapropoxytitanium, tetraethoxyzirconium and tetrapropoxyzirconium. And tetraalkoxy zirconium such as triisopropoxyaluminum, and trialkoxycerium such as triisopropoxycerium. As these compounds themselves, known or commercially available compounds can be used.

  Although the addition amount of an alkoxide compound can be suitably set according to the kind etc. of the alkoxide compound to be used etc., it is usually about 0.1-50 mass parts with respect to 100 mass parts of aluminum nitride particles, and is especially 1-10 mass parts. It is more preferable. Thereby, a uniform oxide film can be more reliably formed on the surface of the aluminum nitride particles.

  Preparation of the mixed solution may be carried out using a known mixing device, stirring device or the like. Specific examples include a kneader, a kneader, a rotating vessel stirrer, a stirring reaction tank, a V-shaped stirrer, a double cone stirrer, a screw mixer, a sigma mixer, a flash mixer, an airflow stirrer, a ball mill, an edge runner, etc. Is mentioned. The mixing time may be set so that each component becomes uniform, and can be set as appropriate.

Second Step In the second step, the alkoxide compound is hydrolyzed by adding an acid catalyst to the mixed solution.

  The acid catalyst is not particularly limited, and for example, in addition to inorganic acids such as phosphoric acid, nitric acid, hydrochloric acid, and phosphonic acid, organic acids such as acetic acid, oxalic acid, and citric acid can be used.

  The addition amount of the acid catalyst may be an amount sufficient to hydrolyze the alkoxide compound, and can be appropriately adjusted within a range of 0.05 to 50 g / L, for example. In this case, it is preferable that the pH of the mixed solution is usually set to 6.0 or lower.

  The acid catalyst may be added as it is, but can also be added in the form of an aqueous solution. The concentration in the case of using an aqueous solution may be set as appropriate, but may be, for example, about 0.05 to 100 g / L.

  The method for adding the acid catalyst is not particularly limited, and may be any of a method of adding the whole amount at once, a method of adding in two or more steps, a method of dropping, or the like. Moreover, when adding an acid catalyst, in order to accelerate | stimulate the hydrolysis reaction of an alkoxide compound, it is desirable to add an acid catalyst, stirring.

  In the second step, the alkoxide compound is mainly hydrolyzed in this way, but the reaction time is not limited, and it may be usually in the range of about 30 minutes to 4 hours. In addition, the temperature of the mixture in the second step is not limited, but it is generally preferable to be within a range of about 50 to 90 ° C. from the viewpoint that the hydrolysis reaction can be particularly promoted.

Third Step In the third step, a base catalyst is added to the mixed solution after hydrolysis. By adding the base catalyst, the hydrolyzed alkoxide compound is mainly condensed and deposited on the surface of the aluminum nitride particles. In the present invention, by using a base catalyst in addition to the acid catalyst, the polycondensation reaction easily proceeds in a three-dimensional direction, and as a result, a denser oxide film is formed as compared with the case where only the acid catalyst is used. As a result, it is considered that a filler having a desired [A / B] value can be produced.

  The base catalyst is not particularly limited. For example, in addition to hydroxides such as sodium hydroxide and potassium hydroxide, ammonia, triethylamine, n-butylamine, eletindiamine, monoethanolamine, diethanolamine, triethanolamine, ammonia, ethylenediamine , T-butylamine, 3-aminopropyltriethoxysilane, n-2-aminoethyl-3-aminopropyltriethoxysilane, n-2-aminoethyl-3-aminopropylmethyldimethoxysilane, urea and other nitrogen-containing compounds ( Nitrogen-containing base) and the like.

  The addition amount of the base catalyst may be an amount that allows the above reaction / precipitation to be sufficiently performed, and can be appropriately adjusted within a range of, for example, 0.05 to 100 g / L. In this case, it is preferable that the pH of the mixed solution is usually set to 8.0 or higher.

  In the third step, the hydrolyzed alkoxide compound is mainly precipitated. In this case, the reaction time is not particularly limited, and may usually be in the range of about 30 minutes to 6 hours. Moreover, the temperature of the mixture in the third step is not particularly limited, but it is generally preferable that the temperature be in the range of about 50 to 90 ° C.

Fourth Step In the fourth step, the obtained reaction product is dried in an oxidizing atmosphere.

  In the third step, the reaction product is generated as a solid content in the mixed solution. After the solid is separated by solid-liquid separation as necessary, the reaction product is dried in an oxidizing atmosphere. It ’s fine. The method for solid-liquid separation may be a known method. For example, a method such as filtration or centrifugation can be appropriately employed.

  The drying temperature is not particularly limited, but is usually within a range of 300 ° C. or less, and preferably 100 to 200 ° C. The drying atmosphere may be an oxidizing atmosphere, and for example, it can be dried in the air.

  Further, the drying time may be a time sufficient for forming an oxide film on the surface of the aluminum nitride particles, and can be appropriately set within a range of, for example, about 1 to 20 hours.

  Thus, the filler of the present invention in which the surface of aluminum nitride particles is coated with an oxide film can be obtained. That is, a) the first step of preparing a mixed solution by adding an alkoxide compound to a dispersion in which aluminum nitride particles are dispersed in a solvent; b) hydrolyzing the alkoxide compound by adding an acid catalyst to the mixed solution. A filler obtained by a method comprising a second step, c) a third step of adding a base catalyst to the mixed solution after hydrolysis, and d) a fourth step of drying the obtained reaction product is suitable as the filler of the present invention. Can be adopted.

3. Use of Aluminum Nitride-Based Filler The filler of the present invention can be used as various fillers (fillers). In particular, it can be suitably used as a filler dispersed in the resin. Since the filler of the present invention uses aluminum nitride as the core particles, it has particularly excellent thermal conductivity. For this reason, it can use suitably as a filler for providing high thermal conductivity (heat dissipation) with respect to resin. That is, this invention includes the highly heat conductive resin composition characterized by including this invention filler and a resin component.

  It does not specifically limit as resin (component), It can apply to various thermoplastic resins, thermosetting resins, etc. For example, a silicone resin, an acrylic resin, an epoxy resin, a polyester resin, a polyurethane resin, a polyvinyl acetate resin, a nitrocellulose resin, a fluorine resin, and the like can be given. Among these, the filler of the present invention can be advantageously used as a filler for a resin (for example, a silicone resin) that is polymerized and cured by a catalyst in which nitrogen of aluminum nitride becomes a catalyst poison.

  In the case of adding to the resin, the addition method is not limited. For example, a) various methods such as a method of kneading the filler of the present invention in a molten resin, b) a method of adding the filler of the present invention to a resin powder and then melt kneading. Can be adopted.

  The amount of the filler of the present invention added to the resin can be appropriately set according to the type of resin to be applied, desired thermal conductivity, and the like. For example, although 10-900 mass parts of this invention fillers can be added with respect to 100 mass parts of resin, it is not limited to this. Moreover, as a volume ratio in a resin composition, it can set suitably so that this invention filler may be about 10-80 volume%.

  Moreover, various additives can also be mix | blended in the resin composition in the range which does not prevent the effect of this invention. For example, a surfactant, a curing agent, a crosslinking agent, an ultraviolet absorber, a static eliminating agent, a thickener, a coloring material, a corrosion inhibitor, and the like can be given.

  The resin composition of the present invention can be used as various parts as a molded body. That is, this invention also includes the molded object of the resin composition of this invention. In particular, the molded article of the present invention can be suitably used as a component that requires high heat dissipation (such as a heat-resistant component or a heat dissipation material) such as an electronic component or an automotive component. As the molding method, a known method such as pressure molding or injection molding can be employed depending on the type of resin component used.

  The features of the present invention will be described more specifically with reference to the following examples and comparative examples. However, the scope of the present invention is not limited to the examples.

Example 1
500 g of aluminum nitride powder (trade name “TFZ-N02P”, manufactured by Toyo Aluminum Co., Ltd., average particle diameter D50: 2 μm) was added to 830 g of a solvent (isopropyl alcohol) and suspended. To this solvent were added 59.3 g of tetraethoxysilane diluted with 17 g of isopropyl alcohol and 1.7 g of acetic acid diluted with 51.4 g of ion-exchanged water, and the mixture was heated to 80 ° C. with vigorous stirring. One hour later, 1.7 g of acetic acid diluted with 41.2 g of ion-exchanged water was added, and the mixture was further stirred for 1 hour. Thereby, tetraethoxysilane (silane alkoxide) was hydrolyzed. Thereafter, 6.9 g of ethylenediamine diluted with 80 g of isopropyl alcohol was added dropwise over 2 hours. After the obtained reaction product was collected by filtration, the obtained solid content was dried in the atmosphere at 200 ° C. for 3 hours to obtain a sample of silica-coated aluminum nitride powder. Table 1 shows the amount of silica coated in each example and comparative example (ratio (% by weight) with respect to the aluminum nitride powder).

Example 2
A sample of silica-coated aluminum nitride powder was prepared in the same manner as in Example 1 except that 500 g of aluminum nitride powder (trade name “TFZ-N10P”, manufactured by Toyo Aluminum Co., Ltd., average particle diameter D50: 10 μm) was used as the aluminum nitride powder. Obtained.

Example 3
A sample of silica-coated aluminum nitride powder was prepared in the same manner as in Example 1 except that 500 g of aluminum nitride powder (trade name “TFZ-N15P”, manufactured by Toyo Aluminum Co., Ltd., average particle diameter D50: 15 μm) was used as the aluminum nitride powder. Obtained.

Example 4
Example 1 except that 500 g of aluminum nitride powder (trade name “TFZ-N15P”, manufactured by Toyo Aluminum Co., Ltd., average particle diameter D50: 15 μm) was used as the aluminum nitride powder, and the addition amount of tetraethoxysilane was 20.0 g. In the same manner as above, a sample of silica-coated aluminum nitride powder (filler) was obtained.

Comparative Example 1
A commercially available aluminum nitride powder (trade name “TFZ-N15P”, manufactured by Toyo Aluminum Co., Ltd., average particle diameter D50: 15 μm) was used as the powder sample of Comparative Example 1.

Comparative Example 2
A commercially available aluminum nitride powder (trade name “TFZ-A15P”, manufactured by Toyo Aluminum Co., Ltd., average particle diameter D50: 15 μm) subjected to phosphoric acid treatment was used as a powder sample of Comparative Example 2.

Comparative Example 3
A commercially available aluminum nitride powder (trade name “R15S”, manufactured by Toyo Aluminum Co., Ltd., average particle diameter D50: 15 μm) subjected to silica treatment was used as a powder sample of Comparative Example 3.

Comparative Example 4
50 g of aluminum nitride powder (trade name “TFZ-N15P”, manufactured by Toyo Aluminum Co., Ltd., average particle diameter D50: 15 μm) was dispersed in 500 mL of methanol. After adding 5.6 g of tetraethoxysilane and stirring for 5 minutes, 50 g of water and 3 g of 1N acetic acid were added and stirred for 1 hour. This was dried at 75 ° C. for 18 hours and then calcined at 600 ° C. for 1 hour. In this way, a powder sample of Comparative Example 4 was obtained.

Test example 1
The following physical properties were measured for the powder samples (fillers) in each Example and Comparative Example.

(1) Particle size The average particle size D50 is determined by measuring in an alcohol solvent using a particle size distribution measuring apparatus (trade name “MT3300EXII”, manufactured by Microtrack Bell Co., Ltd.) using a laser diffraction / scattering method. It was. The results are shown in Table 1.

(2) Specific surface area (BET)
The measured value (A) (m ² / g) of the specific surface area is 150 ° C. under a nitrogen atmosphere using a fully automatic specific surface area measuring device (trade name “Macsorb (registered trademark) HM Model-1201”, manufactured by Mountec Co., Ltd.). And it measured by BET method after pre-processing on the conditions for 120 minutes. The results are shown in Table 1.

(3) Calculated value of specific surface area calculated when the shape is spherical The calculated value (CS) (m ² / ml) of the surface area per volume calculated when the shape is spherical is the predetermined particle diameter Is a value obtained by dividing a value Σ (a _i × d _i ) obtained by integrating the representative diameter d _i in the range and the particle surface area a _i of the powder sample distributed in the range by the sum Σa _i of the surface areas of the particles. It calculates based on following formula (1) using an area average diameter (MA).
CS = 6 / MA (1)
(However, MA = {Σ (a _i × d _i )} / Σa _i )
The value obtained by dividing the CS value by the specific gravity (g / ml) of the powder sample (the value converted into the specific surface area based on weight) is B (m ² / g), and the specific surface area is A (m ² / g). ) And the value of [A / B] was determined. The results are shown in Table 1.
In this case, the calculated value calculated | required based on the theoretical density of the aluminum nitride and silicon dioxide which comprise a filler was used for the said specific gravity. For example, since the specific gravity of the filler of Example 1 is 100 parts by mass of aluminum nitride and 3 parts by mass of silicon dioxide, [theoretical density of aluminum nitride 3.26 × (100/103)] + [theoretical density of silicon dioxide 2 .65 × (3/100]) = about 3.24. And since the CS value of the filler of Example 1 is 4.75 m < ² > / mL, it will be 4.75 / 3.24 = about 1.47 m < ² > / g. Therefore, [A / B] value = 3.8 / 1.47 = about 2.6.

(4) Catalytic toxicity In order to evaluate catalytic toxicity to platinum catalyst, silicone resin (trade name “KE-1013”, manufactured by Shin-Etsu Chemical Co., Ltd.) and each powder sample were blended at a volume ratio of 1: 1, and the rotation The mixture was stirred and mixed for 5 minutes using a revolutionary mixer (trade name “Mazerustar”, Kurashiki Boseki Co., Ltd.). The obtained mixture was sandwiched between release sheets and heated at 100 ° C. for 1 hour to cure the resin.
After the resin was cured, it was confirmed whether the resin could be removed from the release sheet. “No” (no catalyst poison) when the uncured resin does not adhere to the release sheet, and “Yes” (with catalyst poison) when the uncured resin sticks to the release sheet. . The results are shown in Table 1.

(5) Viscosity In order to evaluate the filling properties of each powder sample into the resin, a resin composition containing a silicone resin (trade name “KE-1013”, manufactured by Shin-Etsu Chemical Co., Ltd.) and each powder sample is prepared, The viscosity was measured.
Specifically, the above-mentioned silicone resin and each powder sample are blended at a volume ratio of 1: 1, and stirred and degassed for 5 minutes using a rotating and rotating mixer (trade name “Mazerustar”, Kurashiki Boseki Co., Ltd.). It was. With respect to the obtained resin composition, the viscosity was measured under the conditions of 1 rpm and 25 ° C. using a cone plate viscometer (trade name “DV2T”, manufactured by BROOKFIELD). The volume of the resin composition was 1.0 mL. The results are shown in Table 1.

(6) Water resistance 10 g of powder sample and 90 g of ion-exchanged water are put into a glass container (capacity 100 mL), and after sealing the glass container, it is allowed to stand in a constant temperature bath at 40 ° C., and the change in pH over time is observed. did. The results are shown in Table 2.

  As is clear from these results, the fillers of the examples in which the value of [A / B] is in a predetermined range (particularly in the range of 2 to 4) are non-catalytic toxicity comparative examples 3 to 4. It can be seen that the viscosity of the resin composition can be kept low and more excellent water resistance can be exhibited.

Claims (5)

A filler in which an oxide film is formed on the surface of aluminum nitride particles,
For the filler, the measured value of the specific surface area measured by the BET method is A (m ² / g), and the calculated value of the specific surface area calculated when the shape is spherical is B (m ² / g). In this case, the aluminum nitride filler is characterized in that the value of [A / B] is 1 to 29.9. The aluminum nitride filler according to claim 1, wherein the oxide film is at least one of silica and alumina. The aluminum nitride filler according to claim 1 or 2, wherein the average particle diameter D50 is 0.1 to 100 µm. The aluminum oxide filler according to any one of claims 1 to 3, wherein the oxide film is contained in an amount of 0.1 to 50 parts by mass with respect to 100 parts by mass of the aluminum nitride particles. A highly thermally conductive resin composition comprising the aluminum nitride filler according to any one of claims 1 to 4 and a resin component.