JP6516656B2 - Water resistant aluminum nitride powder - Google Patents

Description

  The present invention relates to water resistant aluminum nitride. In particular, it relates to an aluminum nitride powder whose good water resistance is maintained after crushing.

  In recent years, with the increase in power density of semiconductor devices, higher heat dissipation characteristics are required for heat dissipation materials.

  As a material for achieving heat dissipation of semiconductor devices, there is a series of materials called thermal interface materials, and the amount used thereof is rapidly expanding. The thermal interface material is a material for relieving the thermal resistance of the path for dissipating heat generated by the semiconductor element to the heat sink or the housing, and is used in various forms such as sheet, gel, grease, etc. ing.

  The thermal interface material is generally a composite material in which a thermally conductive filler is dispersed in a suitable resin such as an epoxy resin or a silicone resin. As the filler, silica or alumina is often used. However, the thermal conductivity of silica and alumina is only about 1 W / mK and 30 W / mK, respectively. For example, in the case of a composite material using alumina, its thermal conductivity remains at about 1 to 3 W / mK.

While further improvement in heat dissipation performance is required, a thermal interface material using a nitride-based inorganic material having high thermal conductivity as the filler is expanding market share. The development of the thermal conductivity in the nitride-based inorganic material is considered to be due to the fact that the thermal conductivity by phonon propagation is easy because the bonding strength between metal ions and anions is strong. Typically, aluminum nitride is used as the nitride-based inorganic material.
However, aluminum nitride is highly reactive with water, and particularly aluminum nitride in powder form is hydrolyzed by contact with water to form aluminum hydroxide and ammonia. Ammonia is eluted as ammonium ions, which causes the reduction of the insulation of the resin as a conductive substance. It also causes corrosion of the wiring. In an effort to improve such current situation, attempts have been made to modify the surface of aluminum nitride particles.

  For example, Patent Document 1 discloses a technique for improving water resistance by treating aluminum nitride powder with inorganic phosphoric acid. According to this method, although the water resistance of the powder is improved to some extent, the aluminum nitride particles become hydrophilic, the particles are strongly aggregated, and the viscosity characteristics are deteriorated. Powders with strong cohesiveness break apart by applying shear force etc. when blended into resin as a filler, but at that time shock is also applied to the water resistant surface coating and aluminum nitride surface with low water resistance Will be exposed.

  Patent Document 2 discloses a technique for improving water resistance by treating an aluminum nitride powder with an organic phosphoric acid compound, but the organic phosphoric acid compound is heated at 150 to 800 ° C. after the addition of the organic phosphoric acid compound. The components are decomposed, and a strongly cohesive powder as in Patent Document 1 is obtained.

  Patent Document 3 discloses a technique for further improving water resistance by performing an aluminum phosphate treatment on the surface of an aluminum nitride powder. However, even with this technique, a large amount of aluminum phosphate is required to provide sufficient water resistance, and as a result, it is difficult to obtain a powder with weak cohesiveness.

  Patent Document 4 discloses a technique for treating at least one type of phosphoric acid compound selected from the group consisting of phosphoric acid, metal salts of phosphoric acid, and organic phosphoric acids having an organic group having 12 or less carbon atoms. However, the water-resistant aluminum nitride powder obtained is also a cohesive powder, and the reduction of water resistance by crushing can not be avoided.

  In Patent Document 5, the surface of the surface phosphoric acid-treated aluminum nitride powder is further treated with an organosilicon coupling agent, an organophosphoric acid coupling agent, an organotitanium coupling agent containing a phosphate group, or the like. Techniques for improving water resistance are disclosed. According to this technology, it is expected that the function of the coupling agent will improve the water resistance. However, since it is necessary to use a considerable amount to sufficiently exhibit the function of the coupling agent, the surface coating layer of the aluminum nitride powder becomes thick, and a plurality of particles are easily aggregated through the coating layer. Furthermore, when the coupling agent treatment is carried out as described in Patent Document 5, it is possible to disperse relatively hydrophilic aluminum nitride powder and aluminum nitride powder having a phosphoric acid film in a very hydrophobic lower alkane. Become. Therefore, in the dispersion liquid, the powder is in a state of aggregation, and even if the coupling agent dispersion liquid is dropped to the liquid, the aggregation of the obtained powder can not be avoided, and a uniform water-resistant coating can not be formed.

  Any of the above methods is a method of forming a water resistant film on the aluminum nitride surface by a wet method, and even if the water resistant film can be uniformly treated on the particle surface, the solvent is removed at the end of the treatment step Drying process is required. Therefore, it is difficult to avoid aggregation during drying, and the occurrence of water resistance failure due to crushing inevitably occurs. Also, at present, there is no known method for uniformly coating all the aluminum nitride particles by a dry method without a drying step.

JP-A-2-141409 JP-A-2-141410 Unexamined-Japanese-Patent No. 2002-226207 International Publication Number WO2012 / 147999 JP-A-7-33415

  Accordingly, an object of the present invention is to provide a highly reliable water resistant aluminum nitride powder by improving the crushability while maintaining excellent water resistance by the phosphoric acid compound.

  As a result of intensive studies to achieve the above object, the inventors of the present invention coated aluminum nitride with an inorganic phosphoric acid and an organic phosphoric acid compound having a hydrocarbon group having 13 to 28 carbon atoms (hereinafter referred to as “surface It has been found that a water-resistant aluminum nitride powder capable of maintaining high water resistance and maintaining water resistance even when subjected to crushing force or physical impact from the outside is exhibited by performing “treatment”.

  Specific examples of the present invention are as described below.

[1]
An aluminum nitride powder having a surface treatment layer,
The carbon content of the surface treatment layer is 0.001 to 0.35 mass%, and the phosphorus content is 0.003 to 0.55 mass% with respect to 100 mass% of aluminum nitride powder,
The time until the pH reaches 8.5 or the electric conductivity exceeds 150 μS / cm when the powder is dry-processed by a millstone type grinder under the following conditions and kept in ion exchange water at 120 ° C. Water resistant aluminum nitride powder (water resistance) is 24 hours or more.
・ Wheel diameter: 250 mm
・ Speed of rotation: 1800 rpm
-The distance between the upper and lower two grinding wheels: 50 ± 10 times the average particle diameter d ₅₀ (unit: μm) of aluminum nitride powder [2]
The above water resistant aluminum nitride powder in which 15 to 70% by mass of the total phosphorus is eluted as inorganic phosphoric acid in a water elution test. .

  The above water resistant aluminum nitride powder can be suitably obtained by the following method.

  [4] A solution containing 0.01 to 1.6 parts by mass of an inorganic phosphoric acid and 0.002 to 0.4 parts by mass of an organic phosphoric acid compound having a hydrocarbon group having 13 to 28 carbon atoms in terms of orthophosphoric acid A method for producing a water resistant aluminum nitride powder comprising the steps of: contacting 100 parts by mass of aluminum nitride powder; and removing the solvent from the aluminum nitride, wherein the mass ratio of the inorganic phosphoric acid to the organic phosphoric acid compound is inorganic phosphorus Acid / organic phosphoric acid compound = 3 to 30. Further, according to the present invention, there is provided a resin composition comprising the water resistant aluminum nitride powder of any of [1] or [2] and a resin.

  The water resistant aluminum nitride powder of the present invention is maintained without being significantly impaired in water resistance by crushing, and therefore aluminum nitride having low water resistance during handling in the powder state and kneading operation with a resin component. The surface is never exposed and can be used with high reliability.

  The water resistant aluminum nitride powder of the present invention comprises both inorganic phosphoric acid and an organic phosphoric acid compound having a carbon number of 13 to 28 carbon atoms on the surface of particles constituting the aluminum nitride powder (hereinafter, these two When it expresses collectively, it is obtained by processing these with an inorganic phosphoric acid / organic phosphoric acid compound = 3-30 by mass ratio, and it calls "a phosphoric acid compound." By such treatment, a water resistant surface treated layer (hereinafter referred to as a water resistant film) is formed before and after the treatment described later. According to the study of the present inventors, the organic phosphoric acid compound having a carbon number of 13 to 28 carbon atoms should be adsorbed on the surface of aluminum nitride by the treatment using the above-mentioned phosphoric acid compound. However, the carbon number of the compound being adsorbed is difficult to confirm even by using NMR, IR and the like. Therefore, it specifies by the carbon content of 0.001-0.35 mass% which can be checked. The carbon content is preferably 0.006 to 0.16% by mass.

  In addition, although inorganic phosphoric acid is also adsorbed, at least a part thereof is usually eluted by a dissolution test with water, so that its presence can be confirmed. The elution amount is preferably 15 to 70% by mass in terms of the total phosphorus of the water resistant aluminum nitride powder, as compared to before elution. Although it is presumed, most of the inorganic phosphoric acid elutes in the water elution test, but it seems that some strongly bind to the aluminum nitride surface and do not elute. By the presence of the leachable inorganic phosphoric acid, even if a part of aluminum nitride is hydrolyzed and ammonia is generated, it can be retained on the particle surface as ammonium phosphate to prevent the diffusion as an ionic component. It seems to be. Here, the dissolution test using water is a test to measure the inorganic phosphoric acid dissolved in water when a mixture of 2 g of water resistant aluminum nitride powder and 100 g of ion exchanged water is allowed to stand at 120 ° C. for 24 hours. .

  Moreover, since it can not be confirmed whether the phosphorus in the surface treatment layer of water resistant aluminum nitride originates from an inorganic phosphoric acid or it is a thing by an organic phosphoric acid compound, it judges in the ratio with respect to the total phosphorus amount.

The water-resistant aluminum nitride powder of the present invention has a total phosphorus content of 0.003 to 0.55% by mass. Preferably, they are present at a ratio of 0.5 to 45 mg / m ^{2 in} terms of (PO ₄ ). It is assumed that the phosphate compound is adsorbed chemically and / or physically on the surface of the aluminum nitride particles, particularly via the aluminum oxide layer, and this adsorptive layer works as a good water-resistant film, Water resistance is maintained after disintegration. The phosphorus content of the surface treatment layer can be determined by fluorescent X-ray analysis. The said phosphorus becomes a total amount of what is derived from inorganic phosphoric acid, and what is derived from an organic phosphoric acid compound.

  The aluminum nitride powder of the present invention may be of only primary particles, may be an aggregate of aggregated primary particles, or may be in a mixed state thereof. When containing aggregates, the water resistant aluminum nitride of the present invention may be apparently granules.

  The above aggregation in the water resistant aluminum nitride powder of the present invention is weak, and by mixing with water and applying ultrasonic dispersion for several minutes, it becomes present as primary particles in water. That is, only the size (and distribution) of primary particles can be measured with a conventional laser diffraction / scattering particle size distribution analyzer, and the particle size of aggregates can not usually be measured accurately.

  One of the characteristics of the water resistant aluminum nitride powder of the present invention is that the surface treatment layer of phosphoric acid compound is formed on the newly emerging surface of the above aggregate by crushing, and a surface having low water resistance is produced. There is nothing to do. This point was manifested by breaking up the water-resistant aluminum nitride powder produced by the conventionally known method, even if the aggregation surface was not surface-treated and the water resistance was good in the state of aggregates. The new aspect is a feature of the present invention as compared to the inferior water resistance.

  Such characteristics clearly appear when the material dry-processed by a millstone type grinder under the following conditions is maintained in ion exchange water at 120 ° C.

・ Wheel diameter: 250 mm
・ Speed of rotation: 1800 rpm
-The distance between the upper and lower two grinding wheels: 50 ± 10 times the average particle diameter d ₅₀ (unit: μm) of aluminum nitride powder The above-mentioned millstone type grinder is the upper and lower two grinding wheels which can freely adjust the corner It is an apparatus of the mill type which is crushed when an input passes through a gap between two grinding wheels by rotating one grinding wheel at a high speed. The degree of crushing is determined by the diameter of the grinding wheel, the number of revolutions, and the distance between the two upper and lower grinding wheels. Crushing of the water resistant aluminum nitride powder is carried out with a millstone type grinder having a grinding wheel diameter of 250 mm and a rotation speed of 1,800 rpm. The conditions of the distance between the upper and lower two grinding wheels are changed depending on the particle diameter, and are implemented at an interval of 50 ± 10 times the average particle diameter d ₅₀ (unit: μm) of the raw material aluminum nitride powder. For example, if the raw material is a powder having an average particle diameter d ₅₀ = 5.0 μm, the grinding is performed with an interval of 200 to 300 μm.

  The water resistant aluminum nitride powder of the present invention treated under the above conditions has a pH of 8.5 or an electric conductivity of more than 150 μS / cm when held in ion-exchanged water at 120 ° C. The earlier (water resistance) is 24 hours or more. That is, the surface of the aluminum nitride powder, which is inferior in water resistance, is susceptible to hydrolysis on the surface and releases ammonium ions, so that the pH is likely to rise early and the electrical conductivity is likely to rise. The aluminum nitride powder of the present invention preferably has a water resistance of 36 hours or more.

  The above-mentioned processing conditions are determined in order to grasp with quantitativeness, and even when the rotational speed and the distance between the grinding wheels are different from each other, the conventional aluminum nitride powder exhibits a difference in water resistance. In addition, simply by using a pestle and a mortar, the water resistance can be grasped even if the crushing process is performed by hand.

  Also, as mentioned above, the aluminum nitride powder of the present invention may consist of only primary particles. Of course, when it consists only of such primary particles, no new surface will be produced even after being processed by the above-mentioned millstone type grinder (the "disruption" is not carried out), so naturally the water resistance is good (for example, The aluminum nitride powder which has once been subjected to crushing treatment of aggregates may also be the water resistant aluminum nitride powder of the present invention).

  The shape of the primary particles of the water resistant aluminum nitride powder in the present invention is not particularly limited, and may be any shape such as irregular shape, spherical shape, polyhedral shape, columnar shape, whisker shape, and flat shape. Among them, in the filler application, it is desirable to use a spherical shape having good viscosity characteristics and high reproducibility of thermal conductivity.

The particle size is also not particularly limited, but from the viewpoint of usefulness, d ₅₀ is preferably about 0.1 to 100 μm, and more preferably 0.1 to 100 μm. Note d _{50 (average} particle diameter), and wet-measured with a laser diffraction scattering type particle size distribution meter, the cumulative volume of particles have a particle diameter at 50%.

  In the present invention, it is possible to obtain aluminum nitride powder having good water resistance even after treatment with a stone mill, by using both the inorganic phosphoric acid and the organic phosphoric acid compound and further using these in a specific ratio. It has become.

  Hereinafter, a method for producing the water resistant aluminum nitride powder of the present invention as described above will be described.

[Raw material aluminum nitride powder]
As raw material aluminum nitride powder in the manufacturing method of this invention, the powdery thing manufactured by the conventionally well-known method can be used without a restriction | limiting especially. In the present invention, the aluminum nitride powder before the surface treatment is referred to as "raw aluminum nitride powder". Examples of the method for producing the raw material aluminum nitride powder in the present invention include a direct nitriding method, a reduction nitriding method, a vapor phase synthesis method and the like.

  It is preferable that the raw material aluminum nitride powder used in the production of the water resistant aluminum nitride powder of the present invention has an aluminum oxide layer on the surface in order to enhance the treatment efficiency of the water resistance treatment step described later. Specifically, it is desirable that Al—O—Al bond or Al—OH group be present on the surface of the particles constituting the raw material aluminum nitride powder. This aluminum oxide layer may be an oxide film layer formed by natural oxidation when storing the raw material aluminum nitride powder, or may be an oxide film layer formed by an oxidation treatment process performed consciously. This oxidation treatment step may be carried out in the process of producing the raw material aluminum nitride powder, or may be carried out as a separate step after producing the raw material aluminum nitride powder. For example, since the raw material aluminum nitride powder obtained by the reduction nitriding method has an oxidation treatment step in the manufacturing process for the purpose of removing carbon used at the time of reaction, an aluminum oxide layer originally exists on the surface. An oxidation treatment step may be further performed on the aluminum nitride powder obtained by the reduction nitriding method.

  When the oxidation treatment step is performed as a separate step, the conditions are as follows.

  The raw material aluminum nitride powder obtained by various methods is preferably subjected to an oxygen-containing atmosphere at a temperature of preferably 400 to 1,000 ° C., more preferably 600 to 900 ° C., preferably 10 to 600 minutes, more preferably By heating for 30 to 300 minutes, an aluminum oxide layer can be formed on the surface of the raw material aluminum nitride particles. As the oxygen-containing atmosphere, for example, oxygen, air, water vapor, carbon dioxide and the like can be used, but in the context of the object of the present invention, treatment in air, in particular under atmospheric pressure, is sufficient.

  The thickness of the above-mentioned aluminum oxide layer may be determined within a range that does not significantly reduce the thermal conductivity of the raw material aluminum nitride powder and the water-resistant aluminum nitride powder, and preferably about 0.05% to 0.2% of the particle diameter. It is a thickness.

  In the present invention, the raw material aluminum nitride powder may contain a certain amount of impurities. For example, as the sintering aid, alkaline earth, rare earth, Y, etc. may be contained with an upper limit of about 10 parts by mass. Moreover, you may contain boron nitride etc. as an upper limit with about 10 mass parts as an aggregation inhibitor.

  The shape of the primary particles of the raw material aluminum nitride in the present invention is not particularly limited, and may be any shape such as, for example, irregular shape, spherical shape, polyhedral shape, columnar shape, whisker shape, and flat shape. Among them, in the filler application, it is desirable to use a spherical shape having good viscosity characteristics and high reproducibility of thermal conductivity. The water resistant aluminum nitride powder of the present invention can be obtained by surface treatment or the like described later, but the shape of the primary particles of the raw material aluminum nitride powder becomes the shape of the primary particles constituting the water resistant aluminum nitride powder as it is.

  In the present invention, the particle diameter of the raw material aluminum nitride is appropriately determined according to the application of the water resistant aluminum nitride powder, and is not particularly limited. The average particle diameter of the raw material aluminum nitride powder in the present invention, which is a raw material, is preferably about 0.1 to 100 μm. In this order, the primary particle diameter of the raw material aluminum nitride is almost the same as the particle diameter of the primary particles constituting the water resistant aluminum nitride. When the raw material aluminum nitride powder has an aluminum oxide layer, the above particle diameter is a particle diameter including the thickness of the aluminum oxide layer. The average particle size is measured by a wet method using a laser diffraction scattering type particle size distribution meter, and the particle size (d50) at which the cumulative volume of particles is 50% is defined as the average particle size.

The BET specific surface area of the raw material aluminum nitride powder in the present invention is preferably 0.01 to ²⁰ m ² / g.

[Surface treatment agent]
<Inorganic phosphoric acid>
In the method for producing the water resistant aluminum nitride powder of the present invention, known inorganic phosphoric acids can be used without particular limitation. As inorganic phosphoric acid, orthophosphoric acid, diphosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid, phosphorous acid, hypophosphorous acid and the like can be mentioned.

  These may be used alone or in combination of two or more. In addition, the chemical state of the inorganic phosphoric acid used may be changed during the drying step or the additional drying step in the surface treatment. For example, when orthophosphoric acid carries out dehydration condensation among them, and it changes into pyrophosphoric acid and polyphosphoric acid, dehydration condensation with the phosphoric acid group or the phosphonic acid group which the below-mentioned organic phosphoric acid compound has, etc. are mentioned.

  Among the inorganic phosphoric acids listed above, orthophosphoric acid is preferable in terms of availability, storage stability, and price. Orthophosphoric acid is generally commercially available at a concentration of 75% or 85% in a liquid state containing water, and this can be suitably used.

  The amount of inorganic phosphoric acid used for surface treatment is preferably 0.01 to 1.6 parts by mass in terms of orthophosphoric acid with respect to 100 parts by mass of aluminum nitride powder. When the amount is more than 0.01 parts by mass, practically sufficient water resistance can be easily obtained. The elution amount of inorganic phosphoric acid in the above-mentioned water elution test tends to increase as the amount of inorganic phosphoric acid used increases. On the other hand, by setting the amount to 1.6 parts by mass or less, when coated on the surface of aluminum nitride particles, the water resistance of the particles themselves is high, and the thermal conductivity is reduced due to excess inorganic phosphoric acid film. It is possible to eliminate the possibility of causing problems such as deterioration of the curability during use and corrosion of the circuit due to the elution of inorganic phosphoric acid from the filler.

Furthermore, the more preferable amount of the inorganic phosphoric acid used for the surface treatment depends on the specific surface area of the aluminum nitride powder, and the larger the specific surface area, the different the amount of the inorganic phosphoric acid suitable for exhibiting water resistance. Suitable inorganic phosphate content ranges, the surface area 1 m ² per 0.05 to 2.5 parts by weight.

<Organic phosphoric acid compound>
In the production of the water resistant aluminum nitride powder of the present invention, as the organic phosphoric acid compound to be used, known organic phosphoric acid compounds having a hydrocarbon group having 13 to 28 carbon atoms can be used without particular limitation. When the hydrocarbon group has less than 12 carbon atoms, the addition effect is reduced. The carbon number is preferably 16 or more in that higher water resistance can be obtained. On the other hand, when the hydrocarbon group exceeds 28 carbon atoms, the hydrophobicity becomes too high, and phase separation from the inorganic phosphoric acid on the aluminum nitride surface tends to inhibit the formation of a water-resistant film with the inorganic phosphoric acid. The hydrocarbon group may be either an aliphatic hydrocarbon group or an aromatic ring. The hydrocarbon group may be linear or branched. The hydrocarbon chain may further contain a double bond or an oxygen atom.

  Here, the addition effect of the organic phosphoric acid compound refers to the maintenance of the crushability and water resistance of the agglomerated particles. In the surface treatment with only inorganic phosphoric acid, the particles are strongly aggregated due to hydrogen bonding between the phosphoric acid groups, and when crushed, a place with a small amount of inorganic phosphoric acid is generated, and water resistance can not be maintained. On the other hand, when inorganic phosphoric acid and an organic phosphoric acid compound are coated together, the hydrocarbon bond of the organic phosphoric acid compound suppresses inter-particle hydrogen bonding and aggregation, and crushability is improved, so that water resistance is easily maintained. It becomes a powder.

  The organic phosphoric acid compounds that can be used in the present invention are usually represented by any of the following general formulas (1) to (3). In the present invention, unless otherwise specified, the acidic phosphoric acid group (P-OH) possessed by alkylphosphonic acids, alkyl phosphoric acid esters and pyrophosphoric acid esters is referred to as "organophosphoric acid group". Also, "phosphate group" is treated as a generic term that includes both a phosphate group and a phosphonate group.

（Ｒ^１は炭素数１３〜炭素数２８の炭化水素基を表す）

(R ¹ represents a hydrocarbon group having 13 to 28 carbon atoms)

（Ｒ^２は炭素数１３〜炭素数２８の炭化水素基を表す。）

(R ² represents a hydrocarbon group having 13 to 28 carbon atoms.)

（Ｒ^３とＲ^４はそれぞれ炭化水素基を表し、Ｒ^３とＲ^４それぞれが有する炭素数の合計が１３〜２８である。）
本発明の耐水性窒化アルミニウム粉末を製造するために使用できる好適な有機リン酸化合物を具体的に例示すれば、テトラデシルホスホン酸、ヘキサデシルホスホン酸、オクタデシルホスホン酸、イコシルホスホン酸、ドコシルホスホン酸、テトラコシルホスホン酸等のアルキルホスホン酸類；テトラデシルリン酸、ヘキサデシルリン酸、オクタデシルリン酸、ジデシルリン酸、１０−メタクリロイルオキシデシルジハイドロジェンホスフェート、１２−アクリロイルオキシドデシルジハイドロジェンホスフェート、１２−メタクリロイルオキシドデシルジハイドロジェンホスフェート、１６−アクリロイルオキシヘキサデシルジハイドロジェンホスフェート、１６−メタクリロイルオキシヘキサデシルジハイドロジェンホスフェート、２０−アクリロイルオキシイコシルジハイドロジェンホスフェート、２０−メタクリロイルオキシイコシルジハイドロジェンホスフェート、ビス〔８−アクリロイルオキシオクチル〕ハイドロジェンホスフェート、ビス〔８−メタクリロイルオキシオクチル〕ハイドロジェンホスフェート、ビス〔９−アクリロイルオキシノニル〕ハイドロジェンホスフェート、ビス〔９−メタクリロイルオキシノニル〕ハイドロジェンホスフェート、ビス〔１０−アクリロイルオキシデシル〕ハイドロジェンホスフェート、ビス〔１０−メタクリロイルオキシデシル〕ハイドロジェンホスフェート等のアルキルリン酸エステル類；ピロリン酸ビスオクチル、ピロリン酸ビス〔８−アクリロイルオキシオクチル〕、ピロリン酸ビス〔８−メタクリロイルオキシオクチル〕、ピロリン酸ビス〔１０−アクリロイルオキシデシル〕、ピロリン酸ビス〔１０−メタクリロイルオキシデシル〕等のピロリン酸エステル類が挙げられる。

(R ³ and R ⁴ each represent a hydrocarbon group, and the total number of carbon atoms of R ³ and R ⁴ is 13 to 28.)
Specific examples of suitable organic phosphoric acid compounds that can be used to produce the water resistant aluminum nitride powder of the present invention include tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, icosylphosphonic acid, docosylphosphonic acid , Alkyl phosphonic acids such as tetracosyl phosphonic acid; tetradecyl phosphoric acid, hexadecyl phosphoric acid, octadecyl phosphoric acid, didecyl phosphoric acid, 10-methacryloyloxydecyl dihydrogen phosphate, 12-acryloyl oxydodecyl dihydrogen phosphate, 12 -Methacryloyl oxydodecyl dihydrogen phosphate, 16-acryloyloxy hexadecyl dihydrogen phosphate, 16-methacryloyloxy hexadecyl dihydrogen phosphate, 20 Acryloyloxyicosyl dihydrogen phosphate, 20-methacryloyloxyicosyl dihydrogen phosphate, bis [8-acryloyloxyoctyl] hydrogen phosphate, bis [8-methacryloyloxyoctyl] hydrogen phosphate, bis [9-acryloyloxy Alkyl phosphates such as nonyl! Hydrogen phosphate, bis [9-methacryloyloxynonyl] hydrogen phosphate, bis [10-acryloyloxydecyl] hydrogen phosphate, bis [10-methacryloyloxydecyl] hydrogen phosphate; Acid bisoctyl, pyrophosphate bis [8-acryloyloxyoctyl], pyrophosphate bis [8-methacryloyloxyok Le], pyrophosphate bis [10- acryloyloxydecyl] pyrophosphate esters such as pyrophosphate bis [10-methacryloyloxydecyl] and the like.

  These may be used alone or in combination of two or more. In addition, the chemical state of the organic phosphoric acid group may be changed during the drying step or the additional drying step in the process of water resistance treatment. For example, organic phosphoric acid groups or organic phosphoric acid groups and phosphoric acid groups of inorganic phosphoric acid may be dehydrated and condensed to form a polymer.

Further, among the organic phosphoric acid compounds listed above, among the compounds represented by the formula (1), from the viewpoint of heat resistance, alkyl phosphonic compounds in which R ¹ is an alkyl group are desirable. Further, from the viewpoint of imparting water resistance and improving the cohesion between particles, hexadecylphosphonic acid, octadecylphosphonic acid and eicosylphosphonic acid having long-chain hydrocarbon groups are particularly desirable.

  The amount of the organic phosphoric acid compound used for the water resistance treatment is preferably 0.002 to 0.4 parts by mass with respect to 100 parts by mass of the powder of the aluminum nitride particles. If the amount is less than 0.002 parts by mass, the addition effect is small. On the other hand, when the amount exceeds 0.4 parts by mass, the formation of a water resistant film with inorganic phosphoric acid is likely to be inhibited.

  What is important to obtain the water resistant aluminum nitride powder of the present invention is to use the above inorganic phosphoric acid and organic phosphoric acid compound in a mass ratio of inorganic phosphoric acid / organic phosphoric acid compound in the range of 3 to 30 . When the mass ratio of the organic phosphoric acid compound is 30 or more of the inorganic phosphoric acid, the addition effect of the organic phosphoric acid compound is small, and when it is less than 3, the formation of the water resistant film of the inorganic phosphoric acid is inhibited.

  Furthermore, the more preferable amount of the organic phosphoric acid compound used for the water resistance treatment depends on the specific surface area of the particles as in the inorganic phosphoric acid, and the larger the specific surface area, the more suitable the organic phosphoric acid compound to exhibit water resistance. The amount is different. The preferred range of the amount of organic phosphoric acid compound is 0.004 to 0.6 parts by mass per specific surface area.

[Embodiment of surface treatment process]
In the present invention, in order to form a uniform film, the above-mentioned phosphoric acid compound is brought into contact with the raw material aluminum nitride powder while being dissolved in a solvent. If a solvent is not used, it is treated unevenly and has a strong tendency to aggregate.

  In the present invention, after the mixture of the solvent and the phosphoric acid compound portion is brought into contact with the aluminum nitride powder, the solvent is removed, and a water-resistant coating of the phosphoric acid compound is formed on the surface of the aluminum nitride particles through the drying step. And the particles are rendered water resistant. While the solvent remains in a large amount, the phosphoric acid compound is present in both the state adsorbed on the surface of the particle and the state dissolved in the solvent. As the drying progresses and the solvent is removed, the phosphate compound suspended with the solvent is also adsorbed on the particle surface, but probably the phosphate compound physically adsorbs at random on the particle surface, resulting in an uneven state. is there. After further drying, when the solvent has almost disappeared, part or all of the adsorbed phosphate compound is reconstituted on the particle surface to form a uniform water-resistant film.

  In the surface treatment step of treating the inorganic phosphoric acid and the organic phosphoric acid compound, the inorganic phosphoric acid and the organic phosphoric acid compound may be used singly or in combination of two or more kinds.

  The surface treatment step (and / or the subsequent drying step, optionally followed by the additional heating step) of treating the inorganic phosphoric acid and the organic phosphoric acid compound is finally the inorganic phosphorus used to form the surface treatment layer. If the mass ratio of the acid to the organic phosphoric acid compound is inorganic phosphoric acid / organic phosphoric acid compound = 3 to 30, it may be carried out once or twice or more. When the surface treatment step is performed twice or more, the amount and type of each of the inorganic phosphoric acid and the organic phosphoric acid compound may be the same as or different from the first time and the second time or later. From the viewpoint of cost, it is preferable that the surface treatment process be performed once. In addition, since the powder once subjected to the surface treatment step has aggregation due to drying, it may be necessary to apply a higher energy than the first surface treatment step to disperse the powder in the solvent again.

  In the surface treatment, if inorganic phosphoric acid / organic phosphoric acid compound is in the range of 3 to 30, inorganic phosphoric acid and organic phosphoric acid compound may be treated in separate steps, but water resistance is higher. In order to obtain the property aluminum nitride powder, it is preferable to prepare a solution containing both the inorganic phosphoric acid and the organic phosphoric acid compound, and treat with this solution at one time.

<Solvent>
Depending on the choice of solvent, the hydrogen bond between the phosphoric acid compounds is stronger, the dispersion in the solvent is insufficient, and there is a possibility of adsorption as a large aggregate of phosphoric acid compounds on the particle surface. In such a case, there is a possibility that surface reconstruction is insufficient and a uniform water-resistant film can not be obtained.

  Furthermore, the present invention is characterized in that the water-resistant film is formed by both the inorganic phosphoric acid and the organic phosphoric acid compound, but depending on the combination thereof, the same substances form large aggregates in the solvent to form a film. There is also the possibility of unevenness.

  Therefore, it is desirable that the solvent dissolves the inorganic phosphoric acid and the organic phosphoric acid compound uniformly. In this case, when the inorganic phosphoric acid and the organic phosphoric acid compound are treated in separate steps, a solvent in which each is dissolved may be sufficient. For example, the solvent in which the inorganic phosphoric acid is dissolved does not dissolve the organic phosphoric acid compound. good.

  On the other hand, in the case where the inorganic phosphoric acid and the organic phosphoric acid compound are treated simultaneously, it is desirable that the inorganic phosphoric acid and the organic phosphoric acid compound can be uniformly dissolved. In particular, a solvent capable of dissolving each of the inorganic phosphoric acid and the organic phosphoric acid compound alone is desirable. If it is dissolved, the phosphate compound adheres uniformly to the particle surface and tends to form a uniform water-resistant film after the drying step.

  As a solvent used at the surface treatment process in this invention, water, alcohol, ester, ketones, ethers, nitriles etc. can be mentioned. Specific examples of such solvent include, as the above-mentioned alcohols, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol and the like; and as the above-mentioned esters, for example, methyl formate, Ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate etc. as the above ketone; eg acetone, methyl ethyl ketone etc. as the above ethers; eg dioxane, diethyl ether, ethylene glycol monomethyl ether as the above ethers Ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene Recall dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran; as nitriles, such as acetonitrile, benzonitrile and the like, can be exemplified respectively. One of these solvents may be used alone, or two or more thereof may be used in combination.

  Among the solvents listed above, alcohols, ketones and ethers are preferred as solvents which dissolve inorganic phosphoric acid and water contained therein well and also organic phosphoric acid compounds well, and alcohols are more preferred. Further, among alcohols, lower alcohols such as methanol, ethanol and isopropyl alcohol are preferable because they have low boiling points and are easy to evaporate and remove.

  In addition to the solvents listed above, a small amount of water may be added in addition to the water contained in the inorganic phosphoric acid so that the inorganic phosphoric acids do not form aggregates in the solvent. The amount of water is preferably 10% by mass or less of the total solvent.

<Preparation of Slurry>
In the surface treatment step of producing the water resistant aluminum nitride powder in the present invention, a slurry in which the raw material aluminum nitride powder is dispersed is formed in a solution in which the phosphoric acid compound is dissolved. The slurry is, for example, a method of dispersing aluminum nitride powder in a solution containing a desired phosphoric acid compound (A), a method of dissolving a phosphoric acid compound in a solvent in which aluminum nitride powder is dispersed, (B) aluminum nitride Method (C) of mixing a solvent in which the powder is dispersed and a solution containing a phosphoric acid compound (C), a method of creating the above dispersion state in the presence of both aluminum nitride powder and phosphoric acid compound in the solvent D) etc. can be obtained. A particularly preferable dispersion procedure is to prepare first a solution in which both the inorganic phosphoric acid and the organic phosphoric acid compound are uniformly dissolved in a solvent, and then mix the solution with the aluminum nitride powder by the method (A). is there. Here, "homogeneous" refers to a state in which the inorganic phosphoric acid and the organic phosphoric acid compound are dissolved in the solvent, and the transparency of the solvent is maintained as compared to that before the dissolution. Further, in any of the cases (A) to (D) mentioned above, it is preferable to maintain the above-mentioned dispersed state until a preferable contact time described later has elapsed.

  Most of the aluminum nitride particles before being mixed with the solvent are in a state of aggregation in many cases, so that only by mixing with the solvent, the phosphoric acid compound does not spread to the inside of the aggregate without sufficiently dispersing. There is a strong tendency to form a surface without a water resistant coating (1). In addition, even if the phosphate compound permeates into the gaps of the aggregates, the phosphate compound is likely to be shared among the particles (2). Furthermore, on the surface of the aggregate, the amount of the phosphate compound adsorbed to the surface of the aggregated particle is greater than the contact surface of the aggregated particles (3). If there is unevenness (1) to (3) of the water-resistant coating due to the presence of such aggregates, some physical action is added to the aluminum nitride aggregates obtained through the subsequent drying step, and the aggregation is dissolved. At the same time, the surface with a small amount of phosphoric acid compound may be exposed and the water resistance may be impaired. Even in the case where the phosphate compound is shared among the particles (2), when aggregation is released, the phosphate compound remains on only one particle and the phosphate compound is extremely low on the surface of the other particle. there is a possibility. Also in the case of (3), a surface with a small amount of phosphate compound is formed inside the aggregate. Therefore, in order to obtain high water resistance, aluminum nitride is preferably brought into contact with the phosphoric acid compound in a state of being sufficiently dispersed in a solvent.

  Examples of suitable devices for making the slurry in a highly dispersed state include, for example, collision dispersers such as a disperser, homogenizer, ultrasonic disperser, wet ball mill, wet vibration ball mill, wet bead mill, nanomizer, high pressure disperser, etc. be able to. At this time, a method in which the primary particles of aluminum nitride are crushed by applying an impact more than necessary should be avoided because there is a risk of exposing the surface without the oxide film. Among the dispersing devices, preferred are a disperser, a homogenizer, an ultrasonic disperser, and a wet ball mill.

  The contact between the aluminum nitride powder and the phosphoric acid compound in a solvent is preferably performed at a temperature of 0 to 75 ° C., more preferably 10 to 65 ° C., preferably 5 minutes to 24 hours, more preferably 10 minutes to 10 hours Do.

  100-250 mass parts is preferable with respect to 100 mass parts of aluminum nitride powder, and, as for the optimal usage-amount of a solvent, 110-160 mass parts is preferable. By setting the content to 100 parts by mass or more, the viscosity of the slurry composed of the aluminum nitride powder and the solvent can be reduced, and the dispersibility can be improved. Further, by setting the amount to 250 parts by mass or less, the solvent can be evaporated in a short time, and the cost can be reduced.

<Solvent removal and drying>
In order to obtain the water resistant aluminum nitride powder of the present invention, it is necessary to remove the solvent from the above slurry. Although the method of removing the solvent is not particularly limited, for example, the following three methods may be mentioned. The first is evaporation to dryness, which removes the solvent by drying and removes all volatile components such as the solvent and water. The second method is a two-step process in which the solvent is roughly dried and then the solvent is completely removed. The third method is a two-step process of separating the solid component and the liquid component, and then the drying step of completely removing the solvent.

  The first method can be used as long as the heating device can evaporate and remove the solvent from the slurry composed of the phosphoric acid compound and the aluminum nitride powder, specifically, a conical dryer, drum dryer, V-type dryer, vibration dryer, A rocking mixer, a nauta mixer, a ribo cone, a vacuum granulating apparatus, a vacuum emulsifying apparatus, and other stirring type vacuum drying apparatuses can be suitably used. The details of the steps up to the final drying will be described in the section of the drying step below.

  The second method can use an apparatus for volatilizing the solvent from the slurry. Specifically, a rotary evaporator, a thin film drying apparatus, a spray dryer, a drum dryer, a disk dryer, a fluid bed dryer and the like can be mentioned.

  The third method is a filtration method, and any device that separates the slurry into a solid component and a liquid component can be suitably used. Specifically, a suction filtration device, a centrifugal filtration device, a decanter, a gear type centrifuge, a pressure filtration device, a filter press, and a filtration drying device capable of carrying out filtration and drying in one unit can be mentioned. The material of the filter medium to be used, the diameter of the retained particles, the separation conditions and the like may be appropriately selected according to the method to be used and the collection rate.

  As the solvent removal method mentioned above, the first method capable of removing all the solvent in one step is preferable in view of cost. Further, as compared with the third filtration method, unevenness in the amount of phosphoric acid compound on the particle surface is less likely to occur. Thus, when the solvent is removed by the first method, it can be considered that the total amount of the inorganic phosphoric acid and the organic phosphoric acid compound used is adsorbed on the surface of the aluminum nitride.

  It is desirable that the water-resistant aluminum nitride powder of the present invention is completely removed from the water used in the inorganic phosphoric acid and the added water in addition to the solvent used in the final dry product. The presence of water between the particle surface and the phosphate and phosphonic acid groups not only makes the water-resistant film easy to peel off, but the remaining water causes hydrolysis of aluminum nitride and the generated ammonia is phosphoric acid. The combination with the base further makes the water-resistant coating brittle. Here, the final dried product refers to one having a weight reduction rate of less than 0.5% of the water resistant aluminum nitride powder immediately after the drying (measuring the weight reduction rate when dried at 120 ° C. in the atmosphere).

  Therefore, it is preferable to remove the water and dry it simultaneously with the solvent removal step or following the solvent removal step.

  Most preferably, it is a method of removing water simultaneously with the solvent removal step, and the temperature at that time is preferably 5 to 100 ° C., and more preferably 40 to 70 ° C. If the drying temperature is less than 5 ° C., the residual amount of solvent and water is large, and there is a high possibility that final drying will not be achieved. In addition, it takes time to dry, which is not desirable in the process. On the other hand, if drying is performed at 100 ° C. or more in a state in which a large amount of solvent remains, dehydration condensation of the inorganic phosphoric acids rapidly progresses, and unevenness tends to occur in the water-resistant coating on the surface of the aluminum nitride particles. As the additional heating temperature is lower, the elution amount of inorganic phosphoric acid in the above-mentioned elution test with water tends to increase. As a drying apparatus, a ventilation type dryer, a convection type dryer, a vacuum dryer, a conical dryer, a drum dryer, a V-type dryer, a vibrating dryer, a rocking mixer, a nauta mixer, a ribo cone, a vacuum granulating apparatus, a vacuum emulsification apparatus, Other stirring type vacuum drying devices can be suitably used.

  The atmosphere for the drying step is preferably under vacuum, inert gas, or dry air. Among them, in a vacuum, in which the water resistant coating is less deteriorated, in an inert gas is preferable, and in a vacuum is more preferable.

<Additional heating>
Also, additional heat treatment may be added to the final dried product obtained after the drying step. The additional heating has the effect of strengthening the bond between the phosphoric acid compound and the aluminum nitride surface, and the desorption of the phosphoric acid compound from the surface is less likely to occur. In addition, there is also an effect that the phosphoric acid group or phosphonic acid group of the phosphoric acid compound is dehydrated and condensed to separate water molecules. As a result, the water resistant coating becomes stronger, and the storage stability of the water resistant aluminum nitride powder can be enhanced.

  The temperature of the additional heating is carried out above the temperature of the drying step carried out in the previous step. As a specific temperature, 70-250 degreeC is preferable and 80-150 degreeC is more preferable. Below 70 ° C., the effect of additional heating is small. On the other hand, if the temperature exceeds 250 ° C., the water-resistant films are dehydrated and condensed among the particles, whereby the particles are aggregated, and the aggregation of the water-resistant films also occurs. Therefore, unevenness of the water-resistant coating is generated, and when aggregation of aggregated particles is broken by crushing or the like, a portion with less water-resistant coating is easily exposed. Moreover, although a phosphoric acid group and a phosphonic acid group part may change by dehydration etc. by additional heating, heating at the temperature which the organic group which an organic phosphoric acid compound has is not decomposed is desirable. The detachment of hydrocarbon chains by decomposition adversely affects the water resistance and the cohesion of particles.

  Additional heating devices include a ventilation dryer, a convection dryer, a vacuum dryer, a conical dryer, a drum dryer, a V-type dryer, a vibrating dryer, a rocking mixer, a nauta mixer, a ribo cone, a vacuum granulator, and a vacuum emulsification device. Other stirring type vacuum drying devices can be suitably used.

  The atmosphere for additional heating is preferably under vacuum, inert gas, or dry air. Among them, in vacuum, in which the water-resistant coating is less deteriorated, in inert gas is preferable, and in vacuum is more preferable.

<Crushing process>
The water resistant aluminum nitride powder of the present invention is obtained by drying (and additional heating) as described above, but the obtained aluminum nitride powder is a powder having a large amount of agglomerated particles. More specifically, it is a mixture of primary particles and aggregates of primary particles (mostly agglomerated particles) (first water resistant aluminum nitride powder of the present invention). It is preferable that the powder containing such large agglomerated particles is crushed as it has poor operability as a powder and may not be sufficiently dispersed when it is kneaded with a resin.

  The second water-resistant aluminum nitride powder of the present invention obtained by crushing tends to aggregate due to hydrogen bonding, and there is a possibility that reaggregation may occur even if the aggregation is broken, but the reaggregate is hard after drying of the solvent. It is easier to loosen compared to aggregation, and there is no need for additional crushing.

  The method of crushing is preferably dry crushing. It is also desirable to use a relatively mild method that breaks up the aggregates originally formed by drying the slurry. When implemented under an apparatus condition that primary particles or primary particles are firmly sintered and secondary particles having grain boundaries exist, the particle surface without a water resistant film may be exposed, which may cause water resistance failure. There is. The atmosphere of the crushing process is preferably in the air or in an inert gas. Also, the humidity of the atmosphere is preferably not too high, specifically, the humidity is less than 70%, more preferably less than 55%.

Examples of the disintegrating apparatus include dry type disintegrating apparatuses such as a stone mill type grinder, a grinding mill, a cutter mill, a hammer mill and a pin mill. Among them, it is preferable to use a stone mill-type attritor, which can crush aggregates in a short time, and has few crushing unevenness. In addition, coarse particles may be removed by a vibrating sieve or the like after coarse crushing. When using a mill-type attritor, good results can be obtained by using a rotational speed of 500 to 3000 rpm and a distance between the upper and lower two wheels of 30 to ₂₀₀ times the average particle diameter d ₅₀ (unit: μm) of aluminum nitride powder. It is easy to obtain. The diameter of the grindstone may be determined appropriately in accordance with the amount of the first aluminum nitride powder to be crushed.

[Composite material for heat dissipation]
The water resistant aluminum nitride particles obtained by the method of the present invention can be suitably used as a heat radiating composite material by mixing it with a resin.

  As a resin which can be used here, any of a thermoplastic resin and a thermosetting resin can be illustrated. Examples of the thermoplastic resin include polyethylene, polypropylene, ethylene-propylene copolymer, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyacetal, fluororesin (Eg polyvinylidene fluoride, polytetrafluoroethylene etc.), polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, ABS resin, polyphenylene ether (PPE) resin, Modified PPE resin, aliphatic polyamide, aromatic polyamide, polyimide, polyamide imide, polymethacrylic acid, polymethacrylic acid ester (eg polymethacrylic acid) (Eg methyl), polyacrylic acid, polyacrylic ester (eg methyl polyacrylate), polycarbonate, polyphenylene sulfide, polysulfone, polyether sulfone, polyether nitrile, polyether nitrile, polyether ketone, polyether ether ketone, poly ketone, liquid crystal polymer Examples of the thermosetting resin include epoxy resin, acrylic resin, urethane resin, silicone resin, phenol resin, imide resin, thermosetting modified PPE, thermosetting PPE and the like. .

  As a use of the composite material for heat dissipation manufactured using the water-resistant aluminum nitride powder obtained by the method of the present invention, for example, the efficiency of heat generation from semiconductor parts mounted on home appliances, automobiles, notebook personal computers, etc. The material of the thermal radiation member for dissipating heat well can be mentioned. As specific examples of these, for example, a heat release grease, a heat release gel, a heat release sheet, a phase change sheet, an adhesive and the like can be mentioned. The above-mentioned composite material can also be used as an insulating layer used for a metal base board, a printed circuit board, a flexible board, etc. besides these, a semiconductor sealing agent, an underfill, a case, a radiation fin etc.

Hereinafter, the present invention will be more specifically described by way of examples, but the present invention is not limited to these examples.

  The various physical-property measuring methods in this invention are as follows, respectively.

<Average particle size>
The particle diameter of a liquid prepared by dispersing a water resistant aluminum nitride powder at a concentration of 1% by mass in ethanol and dispersing by ultrasonic irradiation for 10 minutes is measured using a laser diffraction scattering type particle size distribution analyzer. In the volume frequency distribution of particle diameter, the value d ₅₀ of the particle diameter at which the cumulative value of volume frequency is 50% is taken as the average particle diameter (median diameter).

<Fluorescent X-ray analysis>
The phosphorus content of the water resistant aluminum nitride powder was measured by a fluorescent X-ray analyzer. The aluminum nitride powder was packed into an aluminum ring with a diameter of 10 mm and pressed for 1 second under pressure 1 ton. The press body was fixed to a jig for fluorescent X-ray analysis, and measurement was performed in a vacuum mode using a fluorescent X-ray analyzer (ZSX Primus II manufactured by Rigaku Corporation, radiation source: Cu-Kα).

<Carbon analysis>
The carbon content of the aluminum nitride powder before the water resistance treatment and the aluminum nitride powder after the water resistance treatment (water resistant aluminum nitride powder) was measured by a carbon analyzer (for example, EMIA-110 manufactured by Horiba, Ltd.). The powder was burned at 1350 ° C. in an oxygen stream until no carbon dioxide gas was generated, and the carbon content of each powder was quantified from the amount of carbon dioxide generated. From the following formula, the carbon content derived from the surface treatment layer of the water resistant aluminum nitride powder was calculated.

Carbon content derived from surface treatment layer (mass%) = (A−B) × 100 / C
A: Carbon amount (mass) after surface treatment
B: Carbon amount (mass) before surface treatment
C: Mass of aluminum nitride powder after surface treatment

<Crushing process>
The water resistant aluminum nitride is crushed using a stone mill type grinder (Supermach Coroider MKZA10-15J, manufactured by Masaki Kogyo Co., Ltd., grinding wheel diameter φ 250 mm, use of alumina non-porous grinding stone MKG-A). The rotational speed of the grindstone is 1800 rpm, and the distance between the upper and lower two grindstones is changed depending on the particle diameter, and the distance is 50 ± 10 times the average particle diameter d ₅₀ (unit: μm) of the raw material aluminum nitride powder. In addition, the crushing process is carried out at 23 ° C. and at a humidity of 50 ± 10%.

<Water resistance test>
Investigate water resistance of water resistant aluminum nitride powder before and after crushing. Place 2 g of water resistant aluminum nitride powder and 100 g of ion exchanged water in a 120 mL polytetrafluoroethylene sealed container (PFA pressure resistant jar, Freon Industrial Co., Ltd.) and allow to stand at 120 ° C. 6 hours, 12 hours The pH of the water after and after 24 hours was measured with pH paper. At this time, it was judged that the water resistance was lost when the pH value became 8.5 or more. At the same time, the conductivity of the supernatant was measured, and it was judged that the water resistance was lost if the conductivity exceeded 100 μS / cm, even if the pH was less than 8.5. Time to loss of water resistance is less than 6 hours (<6), 6 hours or more and less than 12 hours (> 6), 12 hours or more and less than 24 hours (> 12), 24 hours or more and less than 36 hours (> 24), 36 hours It classified into five steps above (> 36), and made this water resistant time.

<Dissolution test>
2 g of water-resistant aluminum nitride powder and 100 g of ion-exchanged water were placed in a 120 ml polytetrafluoroethylene sealed container (PFA pressure-resistant jar, Freon Industrial Co., Ltd.), allowed to stand at 120 ° C., and then cooled to room temperature. The turbid water was centrifuged and the supernatant was discarded. The remaining powder was dried to a water content of 0.5% by mass or less, and the obtained powder was analyzed by fluorescent X-ray analysis to measure the amount of residual phosphorus after elution. Moreover, the content phosphorus of the aluminum nitride before the elution test was also measured, and the carbon content derived from the surface treatment layer of the water resistant aluminum nitride powder was calculated from the following equation.

Amount of phosphorus eluted in water (%) = (A−B) × 100 / A
A: Phosphorus content of aluminum nitride powder before dissolution test (mass)
B: Phosphorus content of aluminum nitride powder after dissolution test (mass)

  In addition, the solubility to the water of a C13 or more organic phosphoric acid compound is 1/5 or less of inorganic phosphoric acid at room temperature. Furthermore, since the inorganic phosphoric acid and the organic phosphoric acid compound contained in the water resistant aluminum nitride in the present invention are inorganic phosphoric acid / organic phosphoric acid compound = 3 to 30, the organic phosphoric acid in the amount of phosphorus detected in the elution test is organic phosphoric acid The proportion of the compound is at most 1/15 of that of inorganic phosphoric acid. Therefore, most of the amount of phosphorus detected in the dissolution test is derived from inorganic phosphate.

  The raw material aluminum nitride, the inorganic phosphoric acid, the organic phosphoric acid compound, and the solvent used in Examples and Comparative Examples are as follows.

<Raw material aluminum nitride>
A1: Aluminum nitride (average particle size 1.2 μm, specific surface area 2.6 m ² / g)
A2: aluminum nitride (average particle diameter 4.9 μm, specific surface area 0.64 m ² / g)
A3: Aluminum nitride (average particle size 29.4 μm, specific surface area 0.20 m ² / g)
A4: Aluminum nitride (average particle size 50.7 μm, specific surface area 0.15 m ² / g)
A5: Aluminum nitride (average particle size 82.3 μm, specific surface area 0.09 m ² / g)

<Inorganic phosphoric acid>
P1: phosphoric acid (orthophosphoric acid; 85% Wako Pure Chemical Industries, Ltd.)
<Organic phosphoric acid compound>
6B: phenylphosphonic acid (Wako Pure Chemical Industries, 95%)
8P: Octyldihydroxylphosphonic acid (Sigma-Aldrich, 97%)
10P: decylphosphonic acid (Sigma-Aldrich, 97%)
12P: dodecyl phosphonic acid (Alfa-Aesar, 95%)
14P: tetradecylphosphonic acid (Sigma-Aldrich, 97%)
16 P: Hexadecylphosphonic acid (Sigma-Aldrich, 97%)
18 P: Octadecylphosphonic acid (Sigma-Aldrich, 97%)
12PO: mono-n-dodecyl phosphate (lauryl phosphate (Toho Chemical Industry))
18 PO: a mixture of mono-n-octadecyl phosphoric acid and di- (n-octadecyl) phosphoric acid (Johoku Chemical Industry)
18 POE: A mixture of mono-n-oleyl phosphate and di- (n-oleyl) phosphate oleyl phosphate (Tokyo Chemical Industry,> 95%)
24PO: a mixture of mono-n-tetracosyl phosphate and di- (n-tetracosyl) phosphate (Johoku Chemical Industry)
・ 2DPO: didecyl phosphate (Tokyo Chemical Industry,> 95%)

<Solvent>
-IPA: isopropyl alcohol (Wako Pure Chemical Industries, special grade)
・ Hexane (Wako Pure Chemical Industries, special grade)
Examples are shown below. The surface treatment conditions are shown in Table 1.

Example 1
500 g of aluminum nitride powder A1, 3.55 g of inorganic phosphoric acid P1, 0.5 g of organic phosphoric acid compound 14P, and 600 g of IPA were added to a 1 L glass beaker and mixed with a stirring blade. Subsequently, ultrasonic waves were applied for 1 hour with an ultrasonic bath while stirring. Thereafter, it was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in vacuum to obtain granular water resistant aluminum nitride powder (first water resistant aluminum nitride powder). The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder (second water resistant aluminum nitride powder) after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 2
A granular water-resistant aluminum nitride powder was obtained in the same manner as in Example 1 except that 0.5 g of the organic phosphoric acid compound 16P was used instead of the organic phosphoric acid compound 14P. Granular powder was crushed and subjected to a water resistance test on the powder before and after crushing. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 3
Granular water-resistant aluminum nitride powder was obtained in the same manner as in Example 1 except that 0.5 g of organic phosphoric acid compound 18P was used instead of organic phosphoric acid compound 14P. Granular powder was crushed, and a water resistance test was carried out on the crushed powder. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 4
A granular water-resistant aluminum nitride powder was obtained in the same manner as in Example 1 except that 0.5 g of the organic phosphoric acid compound 18PO was used instead of the organic phosphoric acid compound 14P. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 5
Granular water-resistant aluminum nitride powder was obtained in the same manner as in Example 1 except that 0.5 g of the organic phosphoric acid compound 18POE was used instead of the organic phosphoric acid compound 14P. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 6
Granular water-resistant aluminum nitride powder was obtained in the same manner as in Example 1 except that 0.5 g of the organic phosphoric acid compound 24PO was used instead of the organic phosphoric acid compound 14P. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 7
Granular water-resistant aluminum nitride powder was obtained in the same manner as in Example 1 except that 0.5 g of organic phosphoric acid compound 2DPO was used instead of organic phosphoric acid compound 14P. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 8
A granular water-resistant aluminum nitride powder was obtained in the same manner as in Example 1 except that 0.2 g of the organic phosphoric acid compound 18P was used instead of the organic phosphoric acid compound 14P. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. The results of carbon analysis and phosphorus content analysis of the powder after the single crushing process are shown in Table 2. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 9
A granular water-resistant aluminum nitride powder was obtained in the same manner as in Example 1 except that 0.75 g of the organic phosphoric acid compound 18P was used instead of the organic phosphoric acid compound 14P. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of particle size distribution measurement and carbon analysis and phosphorus content analysis for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 10
A granular water-resistant aluminum nitride powder was obtained in the same manner as in Example 1, except that 1.0 g of the organic phosphoric acid compound 18P was used instead of the organic phosphoric acid compound 14P. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of particle size distribution measurement and carbon analysis and phosphorus content analysis for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 11
500 g of aluminum nitride powder A2, 2.75 g of inorganic phosphoric acid P1, 0.3 g of organic phosphoric acid compound 18P, and 600 g of IPA were added to a 1 L glass beaker and mixed with a stirring blade. Subsequently, ultrasonic waves were applied for 1 hour with an ultrasonic bath while stirring. Thereafter, it was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in a vacuum to obtain granular water resistant aluminum nitride powder. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 12
500 g of aluminum nitride powder A3, 1.45 g of inorganic phosphoric acid P1, 0.1 g of organic phosphoric acid compound 18P, and 600 g of IPA were added to a 1 L glass beaker and mixed with a stirring blade. Subsequently, ultrasonic waves were applied for 1 hour with an ultrasonic bath while stirring. Thereafter, it was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in a vacuum to obtain granular water resistant aluminum nitride powder. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 13
500 g of aluminum nitride powder A4, 0.9 g of inorganic phosphoric acid P1, 0.05 g of organic phosphoric acid compound 18P, and 600 g of IPA were placed in a 1 L glass beaker and mixed with a stirring blade. Subsequently, ultrasonic waves were applied for 1 hour with an ultrasonic bath while stirring. Thereafter, it was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in a vacuum to obtain granular water resistant aluminum nitride powder. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 14
500 g of aluminum nitride powder A5, 0.55 g of inorganic phosphoric acid P1, 0.04 g of organic phosphoric acid compound 18P, and 600 g of IPA were added to a 1 L glass beaker and mixed with a stirring blade. Subsequently, ultrasonic waves were applied for 1 hour with an ultrasonic bath while stirring. Thereafter, it was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in a vacuum to obtain granular water resistant aluminum nitride powder. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 15
Granular water-resistant aluminum nitride powder was obtained in the same manner as in Example 3 except that heating was additionally performed for 3 h with a vacuum dryer at 250 ° C. for 3 h instead of additional heating at 120 ° C. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 16
500 g of aluminum nitride powder A1, 3.55 g of inorganic phosphoric acid P1, and 600 g of IPA were placed in a 1 L glass beaker and mixed with a stirring blade. Subsequently, ultrasonic waves were applied for 1 hour with an ultrasonic bath while stirring. Thereafter, it was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in vacuum to obtain granular powder.

  500 g of the obtained inorganic phosphoric acid-treated powder was placed in a 1000 ml eggplant flask, and then 600 ml of IPA in which 0.5 g of organic phosphoric acid compound 18P was dissolved was added. Stirring was performed with a stirring blade, and ultrasonic waves were applied for 1 hour with an ultrasonic bath. Thereafter, it was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in vacuum to obtain granular powder. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Example 17
500 g of aluminum nitride powder A1, 3.55 g of inorganic phosphoric acid P1, and 600 g of IPA were placed in a 1 L glass beaker and mixed with a stirring blade. Subsequently, ultrasonic waves were applied for 1 hour with an ultrasonic bath while stirring. Thereafter, it was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in vacuum to obtain granular powder.

  500 g of the obtained inorganic phosphoric acid-treated powder was placed in a 1000 ml eggplant flask, and 600 ml of IPA in which 0.5 g of organic phosphoric acid compound 18 POE was dissolved was further added. Stirring was performed with a stirring blade and ultrasonic waves were applied for 1 hour with an ultrasonic bath. Thereafter, it was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in vacuum to obtain granular powder. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Comparative Example 1
Granular powder was obtained in the same manner as in Example 1 except that the organic phosphoric acid compound was not used. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Comparative example 2
A granular powder was obtained in the same manner as in Example 1 except that 0.5 g of 6P was used instead of the organic phosphoric acid compound 14P. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Comparative example 3
A granular powder was obtained in the same manner as in Example 1 except that 0.5 g of 10P was used instead of the organic phosphoric acid compound 14P. After cooling, the granular powder was crushed and the water resistance test was performed on the powder before and after the crushing and removal. The results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Comparative example 4
A granular powder was obtained in the same manner as in Example 1 except that 0.5 g of 12PO was used instead of the organic phosphoric acid compound 14P. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Comparative example 5
A granular powder was obtained in the same manner as in Example 1, except that 0.1 g of the organic phosphoric acid compound 18P was used instead of the organic phosphoric acid compound 14P. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. The results of carbon analysis and phosphorus content analysis of the powder after the single crushing process are shown in Table 2. The average particle size was the same as that of the raw material AlN before and after crushing.

Comparative example 6
Granular powder was obtained in the same manner as in Example 1 except that 3.0 g of organic phosphoric acid compound 18P was used instead of organic phosphoric acid compound 14P. Granular powder was crushed in an agate mortar in the atmosphere, and a water resistance test was performed on the powder before and after crushing. The water resistance test results are shown in Table 2. The results of carbon analysis and phosphorus content analysis of the powder after the single crushing process are shown in Table 2. The average particle size was the same as that of the raw material AlN before and after crushing.

Comparative example 7
Granules were prepared in the same manner as in Example 1 except that 16 g of inorganic phosphoric acid P1 was used instead of inorganic phosphoric acid P1 and 3.55 g, and 18 P and 0.5 g were used instead of organic phosphoric acid compound 14P and 0.5 g. Powder was obtained. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

Comparative Example 8
500 g of aluminum nitride powder A1, 3.55 g of inorganic phosphoric acid P1, and 600 g of IPA were placed in a 1 L glass beaker and mixed with a stirring blade. Subsequently, ultrasonic waves were applied for 1 hour with an ultrasonic bath while stirring. Thereafter, it was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in vacuum to obtain granular powder.

  50 g of the obtained inorganic phosphate-treated powder was placed in a 500 ml Erlenmeyer flask, and 200 ml of hexane was further added. The mixture was stirred with a stirring blade and heated to 60 ° C. In a separate container, 0.5 g of organic phosphoric acid compound 18POE, 12.5 g of hexane, and 12.5 g of IPA were added, and a solution in which 18 POE was dissolved was prepared. This solution was added dropwise to the stirred inorganic phosphoric acid-treated powder in hexane over 10 minutes. The obtained suspension was dried under reduced pressure at 50 ° C. using a rotary evaporator to obtain a semi-dried powder. Further, it was dried for 12 h in a vacuum dryer at 50 ° C., and then heated for an additional 3 h in a vacuum dryer at 120 ° C. Thereafter, it was allowed to cool in vacuum to obtain granular powder. The granular powder was crushed and the water resistance test was carried out on the powder before and after the crushing and removal. The water resistance test results are shown in Table 2. In addition, Table 2 shows the results of carbon analysis, phosphorus content analysis and dissolution test for the powder after the single crushing process. The average particle size was the same as that of the raw material AlN before and after crushing.

  As apparent from Table 2, the water resistant aluminum nitride particles described in Examples 1 to 17 exhibited water resistance of 24 hours or more after the crushing treatment. On the other hand, in Comparative Examples 1 to 6, the water resistance was shown for 24 hours or more before the crushing treatment, but the water resistance could be maintained for less than 24 hours after the crushing treatment. In Comparative Example 7, an excessive amount of phosphoric acid was present, and the electrical conductivity was too high in the water resistance test. In Comparative Example 8, although the lower alkane hexane was used as the solvent and the organic phosphoric acid compound was treated in a large amount, even the sample before the crushing treatment did not have water resistance for 24 hours.

Claims (7)

It is an aluminum nitride powder which has a surface treatment layer, The carbon content of the surface treatment layer is 0.001 to 0.35 mass% with respect to 100 mass% of the aluminum nitride powder, and the phosphorus content is 0.003 to 0.55% by mass,
The time until the pH reaches 8.5 or the electric conductivity exceeds 150 μS / cm when the powder is dry-processed by a millstone type grinder under the following conditions and kept in ion exchange water at 120 ° C. Water resistant aluminum nitride powder (water resistance) is 24 hours or more.
・ Wheel diameter: 250 mm
・ Speed of rotation: 1800 rpm
-The distance between the upper and lower two grinding wheels: 50 ± 10 times the average particle diameter d ₅₀ (unit: μm) of aluminum nitride powder   The water-resistant aluminum nitride powder according to claim 1, wherein 15 to 70% by mass of the total phosphorus is eluted as inorganic phosphoric acid in a water elution test.   A solution containing 0.01 to 1.6 parts by mass of an inorganic phosphoric acid and 0.002 to 0.4 parts by mass of an organic phosphoric acid compound having a hydrocarbon group having 13 to 28 carbon atoms in terms of orthophosphoric acid; It is a manufacturing method of water resistant aluminum nitride powder which has a process of making a slurry contact by contacting 100 mass parts of aluminum nitride powder, and a process of removing a solvent from the slurry, which is a mass ratio of inorganic phosphoric acid and organic phosphoric acid compound. The method for producing a water resistant aluminum nitride powder according to claim 1 or 2, wherein the inorganic phosphoric acid / organic phosphoric acid compound is 3 to 30.   The manufacturing method of the water-resistant aluminum nitride powder of Claim 3 whose organic phosphoric acid compound which has a C13-C28 hydrocarbon group is an alkyl phosphonic acid.   The method for producing a water resistant aluminum nitride powder according to claim 3 or 4, wherein the solution containing the inorganic phosphoric acid and the organic phosphoric acid compound is a homogeneous solution.   The method for producing a water resistant aluminum nitride powder according to claim 1 or 2, wherein the water resistant aluminum nitride powder obtained by the method according to any one of claims 3 to 5 is crushed.   A resin composition comprising the water resistant aluminum nitride powder according to claim 1 and a resin.