Aluminum nitride filler, method for producing aluminum nitride filler, resin composition, and method for producing resin composition

Abstract

Provided is an aluminum nitride filler containing aluminum nitride particles and a coating (a) containing a compound (A) having a polyethyleneimine skeleton and a polyalkylene oxide chain and having a weight average molecular weight of 2,000-10,000. Also provided is a method for producing the aluminum nitride filler.

Description

Aluminum nitride filler, method for producing aluminum nitride filler, resin composition, and method for producing resin composition

[0001] The present invention relates to an aluminum nitride filler, a method for producing an aluminum nitride filler, a resin composition, and a method for producing a resin composition.

[0002] Nitride fillers have high thermal conductivity and excellent electrical insulation. Therefore, nitride fillers are promising fillers for resin compositions used in products such as heat dissipation sheets and encapsulants for electronic components. Aluminum nitride reacts with water to undergo hydrolysis, converting into aluminum hydroxide, which has low thermal conductivity. Furthermore, aluminum nitride generates corrosive ammonia during hydrolysis.

[0003] Techniques proposed for improving the moisture resistance of aluminum nitride include a method of forming a layer made of Si—Al—O—N on the surface of aluminum nitride powder (see, for example, Patent Document 1), a method of forming a coating layer on the surface of aluminum nitride powder using a silicate treatment agent and a coupling agent (see, for example, Patent Document 2), a method of treating the surface of aluminum nitride powder with a silicate treatment agent to leave organic groups on the surface of aluminum nitride powder (see, for example, Patent Document 3), a method of surface-modifying the surface of aluminum nitride particles with a specific acidic phosphate ester (see, for example, Patent Document 4), and an improved method that maintains better moisture resistance and thermal conductivity (see, for example, Patent Document 5).

[0004] The moisture-proof aluminum nitride powder of Patent Document 1 is prepared by applying a silicate ester layer to the surface of aluminum nitride powder and then firing at a high temperature of 350 to 1000°C to form a layer composed of Si-Al-O-N on the surface. The aluminum nitride powder of Patent Document 2 is subjected to surface treatment with a silicate treatment agent and a coupling agent followed by high-temperature heat treatment to form a coating layer on the surface. The aluminum nitride powder of Patent Document 3 is subjected to surface treatment with a silicate treatment agent followed by heat treatment at a temperature not exceeding 90°C, thereby leaving organic groups and improving compatibility with resins. The surface-modified particles of Patent Document 4 are aluminum nitride particles surface-modified with a specific acidic phosphate ester to improve moisture resistance. The surface-modified particles of Patent Document 5 are excellent moisture-resistant aluminum nitride particles coated with an extremely thin, uniform, and dense silica film.

[0005] Boron nitride is also used in various heat dissipation components due to its high thermal conductivity, does not have the moisture resistance problem of aluminum nitride, and is further developed for a variety of applications by taking advantage of its low dielectric constant. However, even with boron nitride, the primary particles are plate-shaped, which means that there are few active sites on which silane coupling agents can be effective, and these are localized on the edge surfaces. Therefore, when boron nitride is highly loaded, there are problems with compatibility with resins and the slurry viscosity tends to increase.

[0006] Japanese Patent No. 3446053 Japanese Patent No. 4088768 Japanese Patent No. 4804023 Japanese Patent Laid-Open Publication No. 2015-71730 International Publication No. 2020 / 040309

[0007] Conventional techniques have been widely used to improve the moisture resistance of aluminum nitride, taking advantage of its high thermal conductivity. However, there has been a problem in that the viscosity of the resulting resin composition tends to increase when aluminum nitride is mixed with an epoxy resin. In particular, aluminum nitride that has been coated with multiple layers to improve moisture resistance without reducing the inherent high thermal conductivity of aluminum nitride has a problem in that the viscosity increases more when mixed with an epoxy resin.

[0008] Furthermore, resin compositions containing aluminum nitride fillers and epoxy resins and used in products such as heat dissipation sheets and sealing materials for electronic components are required to have good adhesive strength so that they can be used in a variety of applications.

[0009] The present invention has been made in view of the above circumstances, and aims to provide an aluminum nitride filler that can suppress an increase in viscosity when mixed with an epoxy resin and can suppress a decrease in adhesive strength after curing of an epoxy resin-containing resin composition, a method for producing the aluminum nitride filler, a resin composition containing the aluminum nitride filler, and a method for producing the resin composition.

[0010] As a result of extensive research, the present inventors have found that an aluminum nitride filler having aluminum nitride particles and a coating containing a specific compound can solve the above problems, and have completed the present invention. That is, the present invention has the following features.

[0011] [1] An aluminum nitride filler comprising aluminum nitride particles and a coating (a) containing a compound (A) having a polyethyleneimine skeleton and a polyalkylene oxide chain and having a weight-average molecular weight of 2,000 or more and 10,000 or less. [2] The aluminum nitride filler according to [1] above, which contains a silicon-containing oxide coating (b). [3] The aluminum nitride filler according to [1] or [2] above, which contains an organosilicon compound coating (c) having a silanol group. [4] The aluminum nitride filler according to [3] above, in which the coating (a) and the organosilicon compound coating (c) are adjacent to each other. [5] The specific surface area (m ) of the aluminum nitride particles determined by the BET method ２ / g) ２ The compound (A) was added at 5.0 × 10 -4 g or more 5.0×10 -2 [6] The aluminum nitride filler according to any one of the above [1] to [4], wherein the specific surface area (m 2 ) of particles containing the silicon-containing oxide coating (b) and the aluminum nitride particles is less than 100 μm. ２ / g) ２The compound (A) was added at 5.0 × 10 -４ g or more 5.0×10 -２ [7] The aluminum nitride filler according to the above [2], wherein the specific surface area (m 2 ) of particles containing the silanol group-containing organosilicon compound coating (c) and the aluminum nitride particles is determined by the BET method. ２ / g) ２ The compound (A) was added at 5.0 × 10 -４ g or more 5.0×10 -２ [8] The aluminum nitride filler according to the above [3] or [4], wherein the specific surface area (m 2 ) of particles containing the silicon-containing oxide coating film (b), the silanol group-containing organosilicon compound coating film (c), and the aluminum nitride particles is determined by the BET method. ２ / g) ２ The compound (A) was added at 5.0 × 10 -4 g or more 5.0×10 -2The aluminum nitride filler according to [3] or [4] above, containing less than g. [9] A method for producing an aluminum nitride filler containing aluminum nitride particles and a coating (a) containing a compound (A) having a polyethyleneimine skeleton and a polyalkylene oxide chain and a weight-average molecular weight of 2,000 to 10,000, the method comprising a fourth step of forming the coating (a).

[10] A method for producing an aluminum nitride filler according to [9] above, comprising a first step of coating with an organosilicon compound having active hydrogen, and a second step of forming a silicon-containing oxide coating (b) by heating.

[11] A method for producing an aluminum nitride filler according to [9] or

[10] above, comprising a third step of coating with an organosilicon compound having active hydrogen by vapor deposition, and treating the coated organosilicon compound with a basic substance to form an organosilicon compound coating (c) having a silanol group.

[12] A resin composition comprising the aluminum nitride filler according to any of [1] to [8] above, and an epoxy resin.

[13] A method for producing the resin composition according to

[12] above, comprising a step I of adding and mixing the aluminum nitride filler with the epoxy resin.

[14] A method for producing the resin composition according to

[12] above, comprising a step II-1 of obtaining a composition i containing the compound (A) and the epoxy resin, and a step II-2 of adding and mixing at least one type of particle selected from aluminum nitride particles, particles containing a silicon-containing oxide coating (b) and aluminum nitride particles, particles containing an organosilicon compound coating (c) and aluminum nitride particles, and particles containing a silicon-containing oxide coating (b), an organosilicon compound coating (c), and aluminum nitride particles to the composition i.

[0012] According to the present invention, it is possible to provide an aluminum nitride filler that can suppress an increase in viscosity when mixed with an epoxy resin and can suppress a decrease in adhesive strength after curing of an epoxy resin-containing resin composition, a method for producing the aluminum nitride filler, a resin composition containing the aluminum nitride filler, and a method for producing the resin composition.

[0013] The present invention will be described in detail below. The present invention also includes any embodiment in which the details described herein are arbitrarily selected or arbitrarily combined. In this specification, preferred definitions can be selected arbitrarily, and combinations of preferred definitions are more preferable. In this specification, the expression "XX to YY" means "XX or more and YY or less." In this specification, for preferred numerical ranges (e.g., ranges of content, etc.), lower and upper limits described in stages can be independently combined. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to form "10 to 60."

[0014] In this specification, the term "50% cumulative volume particle size (D50)" refers to the particle size at which the cumulative volume of a particle size distribution is 50%. D50 is determined from the particle size distribution measured by a laser diffraction scattering method. Specifically, it can be measured using a laser diffraction / scattering particle size distribution analyzer (manufactured by Microtrac Bell Corporation, product name: Microtrac MT3300EX2) or the like.

[0015] <Aluminum Nitride Filler> The aluminum nitride filler of the present invention contains aluminum nitride particles and a coating (a) containing a compound (A) having a polyethyleneimine skeleton and a polyalkylene oxide chain and having a weight-average molecular weight of 2000 or more and 10000 or less. When the aluminum nitride filler contains the coating (a) containing the compound (A), an increase in viscosity when mixed with an epoxy resin can be suppressed, and a decrease in adhesive strength after curing of the epoxy resin-containing resin composition can be suppressed.

[0016] [Aluminum nitride particles] In the aluminum nitride filler of the present invention, the aluminum nitride particles used as a raw material can be any known product, such as a commercially available product. The method for producing the aluminum nitride particles is not particularly limited, and examples thereof include a direct nitriding method in which metallic aluminum powder is directly reacted with nitrogen or ammonia, and a reduction-nitriding method in which alumina is carbon-reduced while being heated in a nitrogen or ammonia atmosphere to simultaneously carry out a nitriding reaction.

[0017] Furthermore, the aluminum nitride particles may be particles obtained by sintering aggregates of aluminum nitride particles into granules. For example, sintered granules made from high-purity aluminum nitride particles may be preferably used.

[0018] Here, high-purity aluminum nitride particles refer to particles with a low oxygen content and a small amount of metal impurities. Specifically, for example, high-purity aluminum nitride particles with an oxygen content of 1 mass% or less and a total content of metal impurities (i.e., metal atoms other than aluminum) of 1000 mass ppm or less are suitable for obtaining higher thermal conductivity of the aluminum nitride particles contained in the aluminum nitride filler. The aluminum nitride particles can be used alone or in combination.

[0019] The oxygen content can be measured using an inorganic analyzer equipped with an oxygen infrared detector, etc. Specifically, the oxygen content can be measured using an oxygen / nitrogen / hydrogen analyzer (ONH836, manufactured by LECO Japan LLC) or the like.

[0020] The total content of metal atoms other than aluminum can be measured using an ICP (Inductively Coupled Plasma) mass spectrometer, etc. Specifically, the total content of metal atoms other than aluminum can be measured using an ICP mass spectrometer (ICPMS-2030, manufactured by Shimadzu Corporation).

[0021] The shape of the aluminum nitride particles used in the present invention is not particularly limited, and examples thereof include amorphous (crushed), spherical, elliptical, plate-like (scale-like), etc. Furthermore, when the aluminum nitride filler is dispersed and contained in the resin composition, the aluminum nitride particles may be the same type of aluminum nitride particles (single particles) having the same shape and structure, or may be a mixture of two or more different types of aluminum nitride particles having different shapes and structures mixed in various ratios.

[0022] When aluminum nitride filler is dispersed in a resin composition, the thermal conductivity of the resin composition increases as the volume ratio (filling amount) of aluminum nitride particles constituting the aluminum nitride filler to the resin composition increases. Therefore, it is preferable that the shape of the aluminum nitride particles is close to spherical, which minimizes the increase in viscosity of the resin composition due to the addition of aluminum nitride filler.

[0023] The particle size at 50% cumulative volume (D50) of the aluminum nitride particles used in the present invention is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.3 μm or more and 200.0 μm or less, even more preferably 0.4 μm or more and 100.0 μm or less, and particularly preferably 0.5 μm or more and 85.0 μm or less.

[0024] When the D50 of the aluminum nitride particles is within the above-mentioned range, even when a resin composition containing aluminum nitride filler is used as a heat dissipation material for mounting power electronic components, it becomes possible to supply a thin heat dissipation material with a minimum thickness, and the moisture resistance of the aluminum nitride filler is further improved, probably because the coating easily covers the surface of the aluminum nitride particles uniformly.

[0025] [Coating (a)] The coating (a) contained in the aluminum nitride filler of the present invention contains a compound (A) having a polyethyleneimine skeleton and a polyalkylene oxide chain and having a weight-average molecular weight of 2,000 or more and 10,000 or less. The content of compound (A) in the coating (a) is not particularly limited, but from the viewpoint of suppressing an increase in viscosity and suppressing a decrease in adhesive strength after curing of the epoxy resin-containing resin composition, it is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 98% by mass or more, and may even be 100% by mass. In other words, the coating (a) may be formed from compound (A).

[0026] The coating (a) may be formed adjacent to the aluminum nitride particles, or may be formed on the aluminum nitride particles via another layer, such as a silicon-containing oxide coating (b) or an organosilicone compound coating (c) having a silanol group, which will be described later. From the viewpoint of effectively obtaining the effects of the present invention, the coating (a) is preferably formed on the outermost layer of the aluminum nitride filler.

[0027] In addition to the compound (A), the coating (a) may contain, as necessary, a dispersant such as a surface treatment agent, a tackifier, etc. Examples of dispersants include DISPERBYK106, BYK-W9010, and BYK-P104 (all manufactured by BYK Japan KK), and FLOWLEN G700 (Kyoeisha Chemical Co., Ltd.). Examples of tackifiers include hydrogenated petroleum resin ARCON M-90 (Arakawa Chemical Industries, Ltd.), terpene resin YS RESIN TO-85, and YS POLYSTAR T80 (all manufactured by Yasuhara Chemical Co., Ltd.).

[0028] (Compound (A)) The compound (A) contained in the coating (a) contained in the aluminum nitride filler of the present invention has a polyethyleneimine skeleton and a polyalkylene oxide chain, and has a weight average molecular weight of 2,000 or more and 10,000 or less. The polyethyleneimine skeleton is an ethyleneimine (-CH ２ CH ２NH-) as a structural unit. This polyethyleneimine skeleton may branch when the hydrogen on the nitrogen is replaced by another chain of ethyleneimine, which is a structural unit. Therefore, the polyethyleneimine skeleton includes not only those having a completely linear structure but also those having a branched chain structure containing primary, secondary, and tertiary amino nitrogens. From the viewpoints of suppressing an increase in viscosity and suppressing a decrease in adhesive strength after curing of the epoxy resin-containing resin composition, the polyethyleneimine skeleton preferably has 3 to 10 nitrogen atoms per molecule.

[0029] The alkylene oxide contained in the polyalkylene oxide chain is preferably an alkylene oxide having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, oxetane, butylene oxide, tetrahydrofuran, etc. Among these, propylene oxide is preferred from the viewpoints of suppressing an increase in viscosity and suppressing a decrease in adhesive strength after curing of the epoxy resin-containing resin composition.

[0030] From the viewpoint of suppressing an increase in viscosity and suppressing a decrease in adhesive strength after curing of the epoxy resin-containing resin composition, the compound (A) preferably has 1 to 10 polyalkylene oxide chains each having 8 to 15 repeating units as a side chain.

[0031] When aluminum nitride particles or a filler containing aluminum nitride particles is mixed with an epoxy resin, the addition of a general surfactant or the like can suppress an increase in viscosity of the resulting resin composition. However, the addition of a general surfactant or the like reduces the adhesive strength at the interface between the aluminum nitride particles or the filler containing aluminum nitride particles and the epoxy resin, thereby reducing the strength of the cured product of the resulting resin composition and the adhesive strength at the phase interface. On the other hand, in the present invention, since compound (A) has a polyethyleneimine skeleton and a polyalkylene oxide chain, it can not only suppress an increase in viscosity of the resin composition, but also suppress a decrease in adhesive strength at the interface between the aluminum nitride filler and the epoxy resin, and suppress a decrease in adhesive strength at the phase interface.

[0032] The weight-average molecular weight of compound (A) is not particularly limited as long as it is 2,000 or more and 10,000 or less, but from the viewpoint of further suppressing an increase in viscosity when mixed with an epoxy resin and suppressing a decrease in adhesive strength after curing of the epoxy resin-containing resin composition, it is preferably 2,500 to 9,000, more preferably 3,000 to 7,000, and even more preferably 3,500 to 6,000. In this specification, the weight-average molecular weight is a value measured by matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS), and specifically, it can be measured by the method described in the Examples.

[0033] When the aluminum nitride filler contains aluminum nitride particles and the coating (a), the content of the compound (A) in the aluminum nitride filler is adjusted to a value that is greater than or equal to the specific surface area (m ) of the aluminum nitride particles determined by the BET method, from the viewpoint of further suppressing an increase in viscosity when mixed with an epoxy resin and suppressing a decrease in adhesive strength after curing of the epoxy resin-containing resin composition. ２ / g) ２ Preferably 5.0 x 10 -４ g or more 5.0×10 -２ g, more preferably less than 2.0 × 10 -３ g or more 4.0×10 -２ g or less, more preferably 4.0 × 10 -３ g or more 3.5×10 -２ In this specification, the specific surface area (m ２ / g) is a value measured by a nitrogen adsorption BET single-point method using a gas flow method. As an evaluation device, a Macsorb HM model-1220 manufactured by Mountech can be used.

[0034] When the aluminum nitride filler contains aluminum nitride particles, a coating (a), and a silicon-containing oxide coating (b), the content of compound (A) in the aluminum nitride filler is set to a value that is greater than the specific surface area (m ) of particles containing the silicon-containing oxide coating (b) and aluminum nitride particles, as determined by the BET method, from the viewpoint of further suppressing an increase in viscosity when mixed with an epoxy resin and suppressing a decrease in adhesive strength after curing of the epoxy resin-containing resin composition. ２ / g)２ Preferably 5.0 x 10 -４ g or more 5.0×10 -２ g, more preferably less than 2.0 × 10 -３ g or more 4.0×10 -２ g or less, more preferably 4.0 × 10 -３ g or more 3.5×10 -２ g or less.

[0035] When the aluminum nitride filler contains aluminum nitride particles, the coating (a), and the silanol group-containing organosilicon compound coating (c), the content of the compound (A) in the aluminum nitride filler is set to a value that is greater than or equal to the specific surface area (m ) of the particles containing the silanol group-containing organosilicon compound coating (c) and the aluminum nitride particles, as determined by the BET method, from the viewpoint of further suppressing an increase in viscosity when mixed with an epoxy resin and suppressing a decrease in adhesive strength after curing of the epoxy resin-containing resin composition. ２ / g) ２ Preferably 5.0 x 10 -４ g or more 5.0×10 -２ g, more preferably less than 2.0 × 10 -３ g or more 4.0×10 -２ g or less, more preferably 4.0 × 10 -３ g or more 3.5×10 -２ g or less.

[0036] When the aluminum nitride filler contains aluminum nitride particles, the coating (a), the silicon-containing oxide coating (b), and the silanol group-containing organosilicon compound coating (c), the content of compound (A) in the aluminum nitride filler is set to a value that is greater than the specific surface area (m ) of particles containing the silicon-containing oxide coating (b), the silanol group-containing organosilicon compound coating (c), and the aluminum nitride particles, as determined by the BET method, from the viewpoint of further suppressing an increase in viscosity when mixed with an epoxy resin and suppressing a decrease in adhesive strength after curing of the epoxy resin-containing resin composition. ２ / g) ２ Preferably 5.0 x 10 -４ g or more 5.0×10 -２ g, more preferably less than 2.0 × 10 -３ g or more 4.0×10-２ g or less, more preferably 4.0 × 10 -３ g or more 3.5×10 -２ g or less.

[0037] [Silicon-containing oxide coating (b)] The aluminum nitride filler of the present invention may contain a silicon-containing oxide coating (b). When the aluminum nitride filler contains the silicon-containing oxide coating (b), moisture resistance is improved. Examples of the "silicon-containing oxide" in the silicon-containing oxide coating (b) include silica and composite oxides of silicon and aluminum. In this specification, oxide also includes oxynitrides, oxycarbonitrides, etc.

[0038] The content of the silicon-containing oxide film (b) in the aluminum nitride filler is preferably 0.8×10 －５ ~2.5 x 10 －２ [SiO ２ Conversion g / m ２ ], more preferably 1.0 × 10 －４ ~2.0 x 10 －２ [SiO ２ Conversion g / m ２ ], more preferably 2.0 × 10 －４ ~1.5 x 10 －２ [SiO ２ Conversion g / m ２ The content of the silicon-containing oxide film (b) in the aluminum nitride filler was determined by multiplying the content of silicon atoms (ΔSi amount) measured by ICP emission spectroscopy by the specific surface area (m ２ / g) ２ ) can be calculated by dividing by

[0039] From the viewpoint of achieving superior moisture resistance, the silicon atom content (ΔSi amount) in the silicon-containing oxide coating (b) is preferably 20 to 2000 ppm by mass, more preferably 30 to 1950 ppm by mass, and even more preferably 40 to 1900 ppm by mass. The ΔSi amount can be measured by ICP atomic emission spectrometry.

[0040] The silicon-containing oxide coating (b) can be formed by the <Method for producing aluminum nitride filler> described below. The silicon-containing oxide coating (b) is preferably formed using the <Organic silicone compound> described below as a raw material.

[0041] From the viewpoint of further improving moisture resistance, the silicon-containing oxide coating (b) is preferably formed on the surface of the aluminum nitride particles. That is, when the aluminum nitride filler of the present invention contains the silicon-containing oxide coating (b), the aluminum nitride particles and the silicon-containing oxide coating (b) are preferably formed adjacent to each other.

[0042] [Organic silicone compound coating (c) having silanol groups] The aluminum nitride filler of the present invention may further contain an organic silicone compound coating (c) having silanol groups (hereinafter, sometimes simply referred to as "organic silicone compound coating (c)"). The organic silicone compound coating (c) has a high affinity with compound (A). Therefore, when the aluminum nitride filler contains the organic silicone compound coating (c), the interfacial adhesive strength between the aluminum nitride filler and the resin contained in the resin composition described below is improved, and when the resin composition is laminated and molded, the adhesive strength at the layer interface is improved.

[0043] The organosilicon compound coating (c) contains an organosilicon compound having a structure represented by the following formula (i):

[0044]

[0045] (In formula (i), R １ is an alkyl group having 1 to 4 carbon atoms.

[0046] The organosilicone compound containing the structure represented by the above formula (i) may be linear, cyclic, or branched.

[0047] The content of the organosilicon compound containing the structure represented by formula (i) in the organosilicon compound coating (c) is not particularly limited, but from the viewpoint of suppressing a decrease in the interfacial adhesive strength between the resin contained in the resin composition and the aluminum nitride filler, it is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 98% by mass or more, and may be 100% by mass. In other words, the organosilicon compound coating (c) may be formed from an organosilicon compound containing the structure represented by formula (i). The content of the organosilicon compound containing the structure represented by formula (i) in the organosilicon compound coating (c) can be calculated by converting the measured value by ICP atomic emission spectroscopy.

[0048] The content of the organosilicon compound coating (c) in the aluminum nitride filler is preferably 0.8×10 -５ ~2.5 x 10 -２ [SiO ２ Conversion g / m ２ ], more preferably 1.0 × 10 -４ ~2.0 x 10 -２ [SiO ２ Conversion g / m ２ ], more preferably 2.0 × 10 -４ ~1.5 x 10 -２ [SiO ２ Conversion g / m ２ The content of the organosilicon compound coating (c) can be determined in the same manner as the content of the silicon-containing oxide coating (b) in the aluminum nitride filler.

[0049] From the viewpoint of suppressing a decrease in the interfacial adhesive strength between the resin contained in the resin composition and the aluminum nitride filler, the organosilicone compound coating (c) is preferably formed adjacent to the coating (a), and from the viewpoint of effectively obtaining the effects of the present invention, it is preferably formed between the aluminum nitride particles and the coating (a). Furthermore, when the aluminum nitride filler contains a silicon-containing oxide coating (b), from the viewpoint of effectively obtaining the effects of the present invention, it is preferable that the aluminum nitride particles and the silicon-containing oxide coating (b) are adjacent to each other, that the surface of the silicon-containing oxide coating (b) opposite to the surface in contact with the aluminum nitride particles is adjacent to the organosilicone compound coating (c), and that the coating (a) is formed as the outermost layer.

[0050] <Method for producing aluminum nitride filler> The method for producing an aluminum nitride filler of the present invention is a method for producing the above-mentioned aluminum nitride filler. That is, the method for producing an aluminum nitride filler of the present invention is a method for producing an aluminum nitride filler containing aluminum nitride particles and a coating (a) containing a compound (A) having a polyethyleneimine skeleton and a polyalkylene oxide chain and having a weight-average molecular weight of 2,000 or more and 10,000 or less, and includes a fourth step of forming the coating (a).

[0051] The method for producing an aluminum nitride filler of the present invention may include, in addition to step (4), a first step of coating with an organosilicon compound having active hydrogen, a second step of forming a silicon-containing oxide film (b) by heating, or a third step of coating with an organosilicon compound having active hydrogen by vapor deposition and treating with a basic substance to form an organosilicon compound film (c) having silanol groups. The method for producing an aluminum nitride filler of the present invention may include, in addition to step (4), a first step of coating with an organosilicon compound having active hydrogen and a second step of forming a silicon-containing oxide film (b) by heating. Furthermore, the method for producing an aluminum nitride filler of the present invention may include, in addition to step (4), a first step of coating with an organosilicon compound having active hydrogen, a second step of forming a silicon-containing oxide film (b) by heating, and a third step of forming an organosilicon compound film (c) having silanol groups by treating with a basic substance. Steps (1) to (4) are described below.

[0052] [Step 1] This step is a step of coating with an organosilicon compound having active hydrogen, and is carried out to form a silicon-containing oxide coating (b). The objects to be coated with the organosilicon compound having active hydrogen are aluminum nitride particles and particles containing the silicon-containing oxide coating (b) and aluminum nitride particles.

[0053] <Organic silicone compound having active hydrogen> In the aluminum nitride filler of the present invention, the organic silicone compound having active hydrogen (hereinafter sometimes simply referred to as "organic silicone compound") used as a raw material for the silicon-containing oxide coating (b) is preferably an organic silicone compound having a structure represented by the following formula (1), which may be linear, cyclic, or branched, from the viewpoint of moisture resistance. The structure represented by the following formula (1) is a hydrogensiloxane unit in which hydrogen is directly bonded to a silicon atom.

[0054]

[0055] (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.)

[0056] In the formula (1), the alkyl group R having 1 to 4 carbon atoms is preferably a methyl group, an ethyl group, a propyl group, a t-butyl group, etc., from the viewpoint of volatilizing the silicone compound, and a methyl group is particularly preferred. In the aluminum nitride filler of the present invention, the organosilicone compound used as a raw material is, for example, an oligomer or polymer containing a structure represented by formula (1).

[0057] As the organosilicone compound, for example, at least one of a compound represented by the following formula (2) and a compound represented by the following formula (3) is suitable.

[0058]

[0059] (In formula (2), R1 and R2 each independently represent a hydrogen atom or a methyl group, at least one of R1 and R2 represents a hydrogen atom, and m represents an integer of 0 to 10.)

[0060]

[0061] (In formula (3), n is an integer of 3 to 6.)

[0062] In particular, a cyclic hydrogensiloxane oligomer in which n is 4 in formula (3) is advantageous in that it can form a uniform silicon-containing oxide coating (b) on the surface of an object to be coated. The weight-average molecular weight of the organosilicone compound containing the structure represented by formula (1) is preferably 100 to 2,000, more preferably 150 to 1,000, and even more preferably 180 to 500. It is presumed that by using an organosilicone compound containing the structure represented by formula (1) with a weight-average molecular weight within this range, it is easier to form a thin, uniform silicon-containing oxide coating (b) on the surface of an object to be coated. In formula (2), m is preferably 1.

[0063] In the first step, the method is not particularly limited as long as the surface of the object to be coated can be covered with the organosilicone compound. Examples of methods for the first step include a dry mixing method in which the organosilicone compound is added to the object to be coated by spraying or other means while stirring the object, followed by dry mixing to coat the object. Examples of powder mixing devices include a Henschel mixer, a container-rotating V-blender, a double-cone blender, a ribbon blender with mixing blades, a screw blender, a sealed rotary kiln, and stirring with a stirrer in a sealed container using a magnetic coupling. The temperature conditions in this case are not particularly limited, depending on the boiling point and vapor pressure of the organosilicone compound, but are preferably 10°C or higher and 200°C or lower, more preferably 20°C or higher and 150°C or lower, and even more preferably 40°C or higher and 100°C or lower.

[0064] Alternatively, the first step may be performed using a gas-phase adsorption method in which the vapor of an organosilicon compound, either alone or in a mixture with an inert gas such as nitrogen gas, is deposited or deposited on the surface of a stationary object to be coated. The temperature conditions in this case vary depending on the boiling point and vapor pressure of the organosilicon compound, but are preferably in the range of 10°C to 200°C, more preferably 20°C to 150°C, and even more preferably 40°C to 100°C. The treatment time is preferably 3 to 7 hours, more preferably 3.5 to 5 hours. If necessary, the system can be pressurized or depressurized (sometimes referred to as a chemical vapor deposition (CVD) method). The equipment that can be used in this case is preferably a sealed system that allows for easy replacement of the gas within the system, such as a glass container, a desiccator, or a CVD apparatus. If the object to be coated is coated with the organosilicon compound without stirring, a longer treatment time is required. However, by intermittently placing the processing container on the vibrator, it is possible to efficiently process areas where powder particles are in contact with each other and are in the shade, or powder particles that are far from the air layer above, by moving the position.

[0065] The amount of the organic silicone compound used in the first step is not particularly limited. When an organic silicone compound having a structure represented by formula (1) is used as the organic silicone compound, the coating amount of the organic silicone compound having a structure represented by formula (1) is determined by the BET method. ２ / g) ２ The coating amount is preferably 0.08 mg or more and 20.0 mg or less, more preferably 0.09 mg or more and 15.0 mg or less, and even more preferably 1.0 mg or more and 10.0 mg or less. With this amount of coating, it is possible to suppress the decrease in thermal conductivity and also to impart sufficient moisture resistance. Note that the specific surface area (m ２ / g) ２ The coating amount of the organosilicon compound containing the structure represented by formula (1) per unit area of ​​the object to be coated is calculated by multiplying the mass difference between the object to be coated before and after coating with the organosilicon compound by the specific surface area (m2) of the object to be coated, which is determined by the BET method. ２ / g) ２ ) can be calculated by dividing by

[0066] The timing of introducing the organosilicon compound may be any stage before the temperature rise, as long as the reaction amount of the organosilicon compound is maintained.

[0067] [Step 2] In this step, the aluminum nitride particles coated with the organosilicon compound, or particles containing the silicon-containing oxide coating (b) coated with the organosilicon compound and aluminum nitride particles, are heated to form the silicon-containing oxide coating (b).

[0068] The heating temperature in the second step is preferably 500° C. or higher and 900° C. or lower, more preferably 550° C. or higher and 850° C. or lower, and even more preferably 600° C. or higher and 800° C. Any general heating furnace can be used as long as it can maintain the temperature within the above range.

[0069] When the heating temperature in this second step is low, a silica coating is formed on the surface of the object to be coated, and silica-coated aluminum nitride particles can be produced. That is, the silicon-containing oxide coating (b) is formed as a silica coating. When the heating temperature in this second step is high, a coating of a complex oxide of silicon and aluminum is formed on the surface of the object to be coated, and aluminum nitride particles coated with a complex oxide of silicon and aluminum can be produced. That is, the silicon-containing oxide coating (b) is formed as a coating of a complex oxide of silicon and aluminum. It is presumed that when the temperature in the second step is high, the aluminum contained in the object to be coated comes out to the surface of the object to be coated and forms a complex oxide with the silicon derived from the organosilicon compound, forming a coating of a complex oxide of silicon and aluminum. From the viewpoint of maintaining the high thermal conductivity of aluminum nitride particles and producing aluminum nitride fillers with excellent moisture resistance, it is preferable that the silicon-containing oxide coating (b) is a silica coating.

[0070] The term "silica coated" means that the particles are coated with a thin film containing silica as the main component. However, since there is a possibility that multiple inorganic compounds exist at the interface between the coated silica and the aluminum nitride particles, when analyzed by ToF-SIMS (Time of Flight Secondary Ion Mass Spectrometry, ION-TOF, TOF.SIMS5), the recombination of secondary ions and decomposition during ionization may also occur, resulting in the formation of AlSiO ４ In some cases, segments such as ions and SiNO ions may be simultaneously detected as secondary components. The composite segments analyzed by ToF-SIMS analysis can also be defined as partial detections of aluminum nitride silica. As a rough guide, if the amount of secondary electrons from silica is greater than that of other fractions, silica can be considered to be the main component.

[0071] In an experiment to confirm the purity of silica with even greater precision, a silica film was formed on an aluminum nitride polycrystalline substrate in the same manner. The surface of the sample was measured using a photoelectron spectrometer (XPS: X-ray Photoelectron Spectroscopy, ULVAC-PHI, Quantera II). The kinetic energy of the detected Si-derived photoelectrons was almost identical to the standard peak of silica, 103.7 eV, indicating that most of the silica was SiO. ２ It is presumed that this structure is the result of the heating process. Depending on the heating temperature, organic components may remain. As long as the effects of the present invention are not impaired, it is entirely possible that organic siloxane components may be present.

[0072] The carbon atom content can be measured using a carbon / sulfur analyzer that uses a non-dispersive infrared absorption method using a tubular electric furnace. Specifically, the carbon / sulfur analyzer (Carbon Analyzer EMIA-821, manufactured by Horiba, Ltd.) can be used for the measurement.

[0073] If the heating temperature (heat treatment temperature) in the second step is 500°C or higher, the silicon-containing oxide coating (b) becomes denser and less permeable to moisture, resulting in better moisture resistance. Heating at 1000°C or lower improves thermal conductivity and moisture resistance. If the heating temperature is 500°C or higher and 1000°C or lower, the silicon-containing oxide coating (b) is uniformly formed on the surface of the object to be coated. If the heating temperature is 500°C or higher, the silicon-containing oxide coating (b) exhibits excellent insulating properties, and if the heating temperature is 1000°C or lower, it is effective in terms of energy cost.

[0074] The heating time is preferably 2 to 10 hours, more preferably 2 to 8 hours, and even more preferably 2 to 7 hours. A heat treatment time of 2 hours or more is preferred because no decomposition products of the organic group (an alkyl group having 4 or less carbon atoms) of the organosilicon compound remain and a silicon-containing oxide coating (b) with an extremely low carbon atom content can be obtained on the surface of the object to be coated. Furthermore, a heating time of 7 hours or less is preferred because the silicon-containing oxide coating (b) can be formed efficiently.

[0075] The atmosphere for the heat treatment in the second step is not particularly limited, and may be, for example, N ２ , Ar, He, or other inert gas atmosphere, ２ , CO, CH ４ The reaction may be carried out in an atmosphere containing a reducing gas such as HCl, or in an atmosphere containing oxygen gas, for example, in the atmosphere (air).

[0076] Furthermore, to further enhance moisture resistance, the first and second steps may be performed sequentially after the heat treatment in the second step. That is, the process of performing the first and second steps sequentially may be repeated. The coating method in which the surface of the object to be coated is covered with an organosilicone compound by gas-phase adsorption in the first step is preferable because it is possible to form a uniform and thin silicon-containing oxide coating (b) compared to coating methods using liquid treatment. Therefore, even if the process of performing the first and second steps sequentially is repeated multiple times, for example, about 2 to 5 times, the aluminum nitride particles can still exhibit good thermal conductivity.

[0077] On the other hand, regarding moisture resistance, a positive correlation is observed between the number of times the first step and the second step are performed in sequence and the moisture resistance, and therefore the number of times the first step and the second step are performed in sequence can be freely selected depending on the level of moisture resistance required for actual applications.

[0078] [Step 3] In this step, an organosilicon compound having active hydrogen is coated on aluminum nitride particles by vapor deposition, and then treated with a basic substance to form an organosilicon compound coating (c) having silanol groups. The organosilicon compound coating (c) may be formed adjacent to the aluminum nitride particles, or a silicon-containing oxide coating (b) may be formed on the surface of the aluminum nitride particles, and then the organosilicon compound coating (c) may be formed on the surface opposite to the surface where the silicon-containing oxide coating (b) contacts the aluminum nitride particles. That is, the organosilicon compound coating (c) may be formed on the surface of aluminum nitride particles, or on the surface of particles containing the silicon-containing oxide coating (b) and aluminum nitride particles. Furthermore, from the viewpoint of suppressing a decrease in the interfacial adhesive strength between the resin contained in the resin composition and the aluminum nitride filler, it is preferable that the organosilicon compound coating (c) be adjacent to the coating (a).

[0079] The method for coating the organosilicon compound having active hydrogen by vapor deposition in this step can be the same as the method for coating the organosilicon compound by vapor deposition in the first step. Furthermore, when the aluminum nitride filler contains a silicon-containing oxide coating (b), the organosilicon compound used in this step can be the same as or different from the organosilicon compound used in the first step. From the viewpoint of improving adhesive strength, the organosilicon compound used in this step is preferably an organosilicon compound having a structure represented by the above formula (1). Furthermore, when coating the aluminum nitride particles with an organosilicon compound having active hydrogen by vapor deposition, components other than the organosilicon compound having active hydrogen may or may not be coated. That is, the coating film coated by vapor deposition may contain components other than the organosilicon compound having active hydrogen, or may be formed from an organosilicon compound.

[0080] In this step, after the organosilicon compound is coated by vapor deposition, the -Si-H groups (active hydrogen groups) possessed by the organosilicon compound are converted to -Si-OH groups (silanol groups) by treating with a basic substance. The basic substance is not particularly limited, and may range from a weak base to a strong base, from a Bronsted base to a Lewis base, as long as an aqueous solution of a strong base that remains as a solid is not used. Examples of the basic substance include aqueous ammonia, monoethylamine, diethylamine, triethylamine, and 2-ethanolamine. From the viewpoint of ease of separation, aqueous ammonia is preferred.

[0081] The treatment with a basic substance can be carried out by immersion or vapor phase film formation.

[0082] (Immersion Method) The immersion method is a film formation method in which an organosilicon compound coated by vapor deposition is immersed in an aqueous solution of a basic substance, etc., to cause the basic substance to act on the organosilicon compound and convert -Si-H groups (active hydrogen groups) to -Si-OH groups (silanol groups). The aqueous solution of the basic substance is preferably ammonia water.

[0083] In the immersion method, the concentration of the basic substance is not particularly limited. For example, when aqueous ammonia is used as the basic substance, the concentration is preferably 0.01 N or more and 10 N or less from the viewpoint of reaction rate, and more preferably 0.1 N or more and 5 N or less, and even more preferably 0.5 N or more and 1.5 N or less, from the viewpoint of suppressing side reactions of the residual organosilicon compound and reducing the risk to the working environment.

[0084] The amount of ammonia water is not particularly limited. However, for example, when the particle diameter (D50) of the aluminum nitride particles used in the reaction is 30 μm or more and 100 μm or less, it is preferable to treat with ammonia water in an amount equal to or greater than one-third of the particle mass and equal to or less than the particle mass. Furthermore, when the particle diameter (D50) is 0.1 μm or more and less than 30 μm, it is preferable to treat with ammonia water in an amount equal to or greater than half the particle mass and equal to or less than twice the particle mass. There are no particular limitations as long as the entire particles, such as aluminum nitride particles, silicon-containing oxide coating (b), and particles containing aluminum nitride particles, are immersed in ammonia water. As the particle size decreases, the particle surface tends to become less wettable with ammonia water immediately after immersion. In such cases, it is preferable to add ethanol in an amount equal to the amount of ammonia water. The addition of ethanol improves the wettability of the particle surface with ammonia water, so further ethanol can be added while stirring. The reaction can be carried out with constant stirring, but the reaction is sufficient even under stationary conditions with intermittent hand mixing. There are no particular limitations on the container for manual mixing, but it is preferable to use a polyethylene wide-mouth bottle with a volume about twice the total volume of the contents.

[0085] The treatment temperature is preferably 20°C or higher and 60°C or lower, but since a large amount of hydrogen is generated immediately after treatment, it is preferable to start the treatment at 20°C for safety reasons.The treatment time is preferably 20 hours or higher and 30 hours or lower, and more preferably 22 hours or higher and 27 hours or lower.

[0086] After the treatment with the basic substance is completed, the residue is filtered by suction filtration using filter paper, and the residue is preferably washed thoroughly with distilled water and then with ethanol to facilitate drying. From the viewpoint of facilitating drying, the residue may be washed with acetone. Alternatively, the residue may be dried by heating at 90 to 120°C for 2 to 4 hours.

[0087] (Vapor Phase Film Formation Method) The vapor phase film formation method is a film formation method in which a basic substance is vapor-phase formed on an organosilicon compound coated by vapor deposition using an aqueous solution of a basic substance, and the basic substance is allowed to act on the organosilicon compound to convert -Si-H groups (active hydrogen groups) to -Si-OH groups (silanol groups). The aqueous solution of the basic substance is preferably ammonia water.

[0088] In the vapor-phase film-forming method, the concentration of the basic substance is not particularly limited. However, for example, when ammonia water is used as the basic substance, it is preferable to perform the process in an airtight container with a vent hole and in a location where local exhaust is possible. The concentration of ammonia water is preferably 0.01 N or more and 10.0 N or less, and more preferably 0.10 N or more and 5.0 N or less, and even more preferably 0.50 N or more and 1.50 N or less, from the viewpoint of suppressing side reactions of residual organosilicon compounds and reducing the risk to the working environment. In the case of the vapor-phase film-forming method, the reaction rate is slower than in the immersion method using ammonia water, so the treatment temperature is preferably 20°C or more and 80°C or less, more preferably 20°C or more and 70°C or less, and even more preferably 30°C or more and 60°C or less. The treatment time in the vapor-phase film-forming method using ammonia water is 24 to 48 hours when the treatment temperature is 20°C, but the treatment time can be shortened by increasing the treatment temperature. For example, when treating at 50°C, sufficient silanol groups can be introduced in 4 to 5 hours.

[0089] In this step, it is preferable to form the organosilicon compound coating (c) by a vapor phase film formation method, since this eliminates the need for filtration and drying steps and allows for efficient production.

[0090] [Step 4] In this step, a coating (a) is formed. The coating (a) is formed on aluminum nitride particles, or particles containing a silicon-containing oxide coating (b) and aluminum nitride particles, or particles containing an organosilicon compound coating (c) and aluminum nitride particles, or particles containing a silicon-containing oxide coating (b), an organosilicon compound coating (c), and aluminum nitride particles (hereinafter sometimes simply referred to as "particles"). For example, when the coating (a) is formed on aluminum nitride particles, an aluminum nitride filler containing aluminum nitride particles and the coating (a) can be produced. There are no particular restrictions on the method for forming the coating (a), but it is preferably formed by an impregnation method or an integral method, and more preferably formed by an impregnation method from the viewpoint of more effectively obtaining the effects of the present invention.

[0091] (Impregnation Method) The impregnation method is a film-forming method in which the particles are immersed in a solution containing compound (A) to form a coating (a) on the surface of these particles. Examples of solvents that can be used in the solution containing compound (A) include isopropanol, 1-methoxy-2-propanol, ethylene glycol monomethyl ether, and dioxolane. Among these, isopropanol is preferred from the viewpoints of a balance between volatility and solubility and low toxicity. The content of compound (A) in the solution containing compound (A) is preferably 8 to 30% by mass, more preferably 10 to 25% by mass, and even more preferably 15 to 20% by mass, from the viewpoint of efficiently forming coating (a).

[0092] The solution containing the compound (A) may contain components other than the compound (A).

[0093] In the impregnation method, the time for immersing the particles is preferably 10 to 60 minutes, more preferably 15 to 50 minutes, and even more preferably 20 to 40 minutes.

[0094] After immersion, the substrate may be heated at 100 to 150° C. for 1 to 3 hours to remove the solvent.

[0095] (Integral Method) The integral method is a film-forming method in which a resin such as an epoxy resin is mixed with a compound (A), and then aluminum nitride particles, or particles containing a silicon-containing oxide coating (b) and aluminum nitride particles, or particles containing an organosilicon compound coating (c) and aluminum nitride particles, or particles containing a silicon-containing oxide coating (b), an organosilicon compound coating (c), and aluminum nitride particles are added to the mixture and mixed to form a coating (a) on the surface of these particles. The resin to be mixed with compound (A) can be an epoxy resin, a phenolic resin, a phenol novolac resin, a urethane resin, an acrylic resin, an epoxy phenolic resin, an epoxy urethane resin, an epoxy acrylic resin, or the like, but epoxy-based resins are preferably used.

[0096] The content of compound (A) in a mixture obtained by mixing a resin such as an epoxy resin with compound (A) is preferably 0.03 to 3.0 mass%, more preferably 0.05 to 1.5 mass%, and even more preferably 0.08 to 0.8 mass%, from the viewpoint of more effectively achieving the effects of the present invention. When the mixture obtained by mixing a resin such as an epoxy resin with compound (A) is used as a resin composition described below, the content of compound (A) in the mixture obtained by mixing a resin such as an epoxy resin with compound (A) is preferably 0.03 to 3.0 mass%, more preferably 0.05 to 1.5 mass%, and even more preferably 0.08 to 0.8 mass%, from the viewpoint of more effectively achieving the effects of the present invention.

[0097] From the viewpoint of more effectively obtaining the effects of the present invention, the amount of the particles added is an amount such that the content of the particles in the resulting resin composition is preferably 50 to 90% by mass, more preferably 55 to 85% by mass, and even more preferably 60 to 80% by mass.

[0098] When producing an aluminum nitride filler containing aluminum nitride particles, a coating (a), and a silicon-containing oxide coating (b), the method for producing the aluminum nitride filler preferably comprises a first step of coating with an organosilicon compound having active hydrogen, a second step of forming the silicon-containing oxide coating (b) by heating, and a fourth step of forming the coating (a). When producing an aluminum nitride filler containing aluminum nitride particles, a coating (a), and an organosilicon compound coating (c), the method for producing the aluminum nitride filler preferably comprises a third step of coating with an organosilicon compound having active hydrogen by vapor deposition, and treating with a basic substance to form the organosilicon compound coating (c) having silanol groups, and a fourth step of forming the coating (a). When producing an aluminum nitride filler containing aluminum nitride particles, a coating (a), a silicon-containing oxide coating (b), and an organosilicone compound coating (c), the method for producing the aluminum nitride filler preferably comprises the following steps: a first step of coating with an organosilicone compound having active hydrogen; a second step of forming the silicon-containing oxide coating (b) by heating; a third step of coating with the organosilicone compound having active hydrogen by vapor deposition, and treating with a basic substance to form the organosilicone compound coating (c) having silanol groups; and a fourth step of forming the coating (a).

[0099] <Resin composition> The resin composition of the present invention contains the aluminum nitride filler of the present invention and an epoxy resin. Since the resin composition of the present invention contains the aluminum nitride filler of the present invention, an increase in viscosity is suppressed and a decrease in adhesive strength after curing is also suppressed.

[0100] The resin composition may contain, in addition to the aluminum nitride filler of the present invention, a filler that is commonly used, such as boron nitride, alumina, silica, or zinc oxide.

[0101] Examples of epoxy resins include bifunctional glycidyl ether type epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, hydrogenated bisphenol A type epoxy resins, and biphenyl type epoxy resins; glycidyl ester type epoxy resins such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; linear aliphatic epoxy resins such as epoxidized polybutadiene and epoxidized soybean oil; heterocyclic epoxy resins such as triglycidyl isocyanurate; and N,N,N',N'-tetraglycidyl-4,4'-diazomethane. Examples of suitable epoxy resins include glycidylamine-type epoxy resins such as methylaminodiphenylmethane, N,N,N',N'-tetraglycidyl-1,3-benzenedi(methanamine), 4-(glycidyloxy)-N,N-diglycidylaniline, and 3-(glycidyloxy)-N,N-diglycidylaniline; and polyfunctional glycidyl ether-type epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, biphenyl aralkyl-type epoxy resins, naphthalene aralkyl-type epoxy resins, tetrafunctional naphthalene-type epoxy resins, and triphenylmethane-type epoxy resins. The above-mentioned epoxy resins can be used alone or in combination of two or more. The coating (a) containing compound (A) exhibits the most favorable viscosity-reducing effect when used in combination with a bisphenol A-type epoxy resin. As the resin component in the resin composition, a bisphenol A type epoxy resin may be used alone, or a bisphenol A type epoxy resin may be used in combination with an epoxy resin other than a bisphenol A type epoxy resin, or a bisphenol A type epoxy resin may be used in combination with a phenol novolac resin.

[0102] When the above-mentioned epoxy resin is used, a curing agent and a curing accelerator may be blended therein. Examples of the curing agent include alicyclic acid anhydrides such as methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and himic anhydride; aliphatic acid anhydrides such as dodecenylsuccinic anhydride; aromatic acid anhydrides such as phthalic anhydride and trimellitic anhydride; bisphenols such as bisphenol A, bisphenol F, and bisphenol S; phenol resins such as phenol-formaldehyde resin, phenol-aralkyl resin, naphthol-aralkyl resin, and phenol-dicyclopentadiene copolymer resin; and organic dihydrazides such as dicyandiamide and adipic acid dihydrazide. Examples of the curing catalyst include amines such as tris(dimethylaminomethyl)phenol, dimethylbenzylamine, 1,8-diazabicyclo(5,4,0)undecene, and derivatives thereof; and imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and derivatives thereof. These may be used alone or in combination of two or more.

[0103] The resin composition of the present invention may contain a resin other than an epoxy resin. The resin other than an epoxy resin is preferably a thermosetting resin, a thermoplastic resin, or a mixture of a thermosetting resin and a thermoplastic resin, as the resulting resin composition has excellent heat resistance. Examples of thermosetting resins include silicone resins such as polydimethylsiloxane, phenolic resins, bismaleimide resins, cyanate resins, urethane resins, (meth)acrylic resins, vinyl ester resins, unsaturated polyester resins, and polyvinyl alcohol acetal resins. These resins may be used alone or in combination of two or more. Furthermore, a mixture of a thermosetting resin with a curing agent and a curing accelerator may also be used.

[0104] Silicone resins include addition reaction-curable silicone resins, condensation reaction-curable silicone resins, and organic peroxide-curable silicone resins, and can be used alone or in combination of two or more types with different viscosities. In particular, when the resulting resin composition is used in applications where flexibility and adhesion are important, examples of silicone resins include addition reaction-curable liquid silicone resins, which do not produce by-products that can cause bubbles and the like. A cured silicone resin can be obtained by reacting an alkenyl-containing organopolysiloxane base polymer with an Si—H-containing organopolysiloxane crosslinker in the presence of a curing agent at room temperature or with heat. Specific examples of organopolysiloxane base polymers include those containing vinyl, allyl, propenyl, or hexenyl groups as alkenyl groups. Vinyl groups are particularly preferred for organopolysiloxanes. Furthermore, a platinum metal-based curing catalyst can be used as the curing catalyst, and the amount added can be adjusted to achieve the desired hardness of the cured resin.

[0105] The resin composition of the present invention may further contain, as necessary, additives such as a flexibility-imparting agent such as silicone, urethane acrylate, butyral resin, acrylic rubber, diene rubber, or a copolymer thereof, a silane coupling agent, a titanium coupling agent, an inorganic ion scavenger, a pigment, a dye, a diluent, or a solvent.

[0106] The total content of the aluminum nitride filler and fillers other than the aluminum nitride filler in the resin composition is not particularly limited as long as it is an amount that results in a desired resin composition, but is preferably 50% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 88% by mass or less, and even more preferably 70% by mass or more and 85% by mass or less. If the total content is 50% by mass or more, good heat dissipation properties can be exhibited, and if it is 90% by mass or less, good workability can be obtained when the resin composition is used.

[0107] The content of aluminum nitride filler in components (fillers) other than the resin component of the resin composition is preferably 30% by mass or more and 100% by mass or less, more preferably 40% by mass or more and 100% by mass or less, and even more preferably 50% by mass or more and 100% by mass or less, of the total content of the aluminum nitride filler and fillers other than the aluminum nitride filler. If the total content is 30% by mass or more, good heat dissipation properties can be exhibited.

[0108] The total content of the epoxy resin and resins other than the epoxy resin in the resin composition is not particularly limited as long as it is an amount that results in a desired resin composition, but is preferably 1% by mass or more and 50% by mass or less, more preferably 3% by mass or more and 40% by mass or less, and even more preferably 5% by mass or more and 30% by mass or less. If the total content is 50% by mass or less, good heat dissipation properties can be exhibited, and if it is 1% by mass or more, good workability can be obtained when the resin composition is used.

[0109] The content of the epoxy resin in the resin composition is preferably 30% by mass or more and 100% by mass or less, more preferably 35% by mass or more and 100% by mass or less, and even more preferably 40% by mass or more and 100% by mass or less, of the total content of the epoxy resin and resins other than the epoxy resin. If the total content is 30% by mass or more, an increase in viscosity when mixed with the epoxy resin can be further suppressed, and a decrease in adhesive strength after curing of the epoxy resin-containing resin composition can be suppressed.

[0110] <Method for Producing Resin Composition> The method for producing a resin composition of the present invention preferably includes the following step I, or the following steps II-1 and II-2: Step I: Adding and mixing the aluminum nitride filler with the epoxy resin Step II-1: Obtaining composition i containing the compound (A) and the epoxy resin Step II-2: Adding and mixing at least one type of particle selected from aluminum nitride particles, particles containing a silicon-containing oxide coating (b) and aluminum nitride particles, particles containing an organosilicon compound coating (c) and aluminum nitride particles, and particles containing a silicon-containing oxide coating (b), an organosilicon compound coating (c), and aluminum nitride particles Steps I, II-1, and II-2 will be described below.

[0111] [Step I] This step involves adding and mixing the aluminum nitride filler of the present invention with an epoxy resin. A resin composition can be obtained through this step. Examples of epoxy resins include those described in the above section on "Resin Composition." In this step, other components described in the above section on "Resin Composition" other than compound (A) and the epoxy resin may also be added. The mixing method is not particularly limited, and examples include a method in which the aluminum nitride filler of the present invention, epoxy resin, resins other than epoxy resins, fillers such as boron nitride, alumina, silica, and zinc oxide, and other additives are mixed together or separately using a dispersing / dissolving device such as a grinder, planetary mixer, planetary mixer, rotation / revolution mixer, kneader, or roll mill, either individually or in combination, and heated as needed to mix, dissolve, and knead the components. From the viewpoint of efficiently forming the coating (a), the method for producing a resin composition preferably includes Step I.

[0112] [Step II-1] This step is a step of obtaining composition i containing compound (A) and an epoxy resin, and composition i is obtained by mixing compound (A) with the epoxy resin. Examples of epoxy resins include the epoxy resins described above in <Resin Composition>. In this step, composition i may be obtained by adding and mixing compound (A) and other components described above in <Resin Composition> other than the epoxy resin. The mixing method in this step is not particularly limited, and examples include a method in which compound (A), the epoxy resin, a resin other than the epoxy resin, and other additives are mixed all at once or in portions using a dispersing / dissolving device such as a grinder, planetary mixer, rotation / revolution mixer, kneader, or roll mill, either alone or in appropriate combinations, and heated as necessary to mix, dissolve, and knead.

[0113] [Step II-2] This step involves adding and mixing at least one particle selected from aluminum nitride particles, particles containing a silicon-containing oxide coating (b) and aluminum nitride particles, particles containing an organosilicon compound coating (c) and aluminum nitride particles, and particles containing a silicon-containing oxide coating (b), an organosilicon compound coating (c), and aluminum nitride particles to composition i. By adding and mixing at least one particle selected from the above particles to composition i, a coating (a) can be formed on the surface of the particles. The mixing method in this step is not particularly limited, and examples include a method in which the components to be mixed are mixed all at once or in portions using a dispersing / dissolving device such as a crusher, planetary mixer, rotation / revolution mixer, kneader, or roll mill, either alone or in combination, and heated as necessary to mix, dissolve, and knead.

[0114] <Uses of Resin Composition> The resin composition obtained by Step I or the following Steps II-1 and II-2 can be formed into a sheet and reacted as necessary to form a heat dissipation sheet. The above-mentioned resin composition and heat dissipation sheet can be suitably used for adhesive applications such as semiconductor power devices and power modules.

[0115] Methods for producing a heat-dissipating sheet include molding a resin composition by sandwiching both sides between substrate films using a compression press or the like, or applying the resin composition to a substrate film using equipment such as a bar coater, screen printer, blade coater, die coater, or comma coater. Furthermore, after molding and application, the heat-dissipating sheet can also undergo additional processing steps such as solvent removal, B-staging by heating, and complete curing. As described above, various forms of heat-dissipating sheets can be obtained depending on the process, making it possible to widely adapt to the target fields of application and usage.

[0116] A solvent can be used to improve workability when applying or forming the resin composition on a substrate film. The solvent is not particularly limited, but examples thereof include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; ether solvents such as 1,4-dioxane, tetrahydrofuran, and diglyme; glycol ether solvents such as methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and diethylene glycol methyl ethyl ether; benzyl alcohol; N-methylpyrrolidone; γ-butyrolactone; ethyl acetate; and N,N-dimethylformamide, which can be used alone or in combination.

[0117] In order to form a resin composition into a sheet, sheet formability that maintains the sheet shape is required. To obtain sheet formability, a high molecular weight component can be added to the resin composition. Examples include phenoxy resin, polyimide resin, polyamide resin, polycarbodiimide resin, cyanate ester resin, (meth)acrylic resin, polyester resin, polyethylene resin, polyethersulfone resin, polyetherimide resin, polyvinyl acetal resin, urethane resin, acrylic rubber, etc. Among them, from the viewpoint of excellent heat resistance and film formability, phenoxy resin, polyimide resin, (meth)acrylic resin, acrylic rubber, cyanate ester resin, polycarbodiimide resin, etc. are preferred, and phenoxy resin, polyimide resin, (meth)acrylic resin, and acrylic rubber are more preferred. They can be used alone or as a mixture or copolymer of two or more types.

[0118] The weight average molecular weight of the high molecular weight component is preferably 10,000 or more and 100,000 or less, and more preferably 20,000 or more and 50,000 or less.

[0119] The good sheet shape with good handleability can be maintained by adding a component having a weight average molecular weight in the range described above.

[0120] The amount of the high molecular weight component added is not particularly limited, but in order to maintain the sheet properties, it is preferably 0.1% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and even more preferably 2% by mass to 10% by mass, relative to the resin composition. Note that an amount of 0.1% by mass to 20% by mass provides good handling properties and allows for the formation of a good sheet or film.

[0121] The substrate film used in the manufacture of the heat dissipation sheet is not particularly limited as long as it can withstand the process conditions such as heating and drying during manufacture, and examples include films made of polyesters having aromatic rings, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), polypropylene films, polyimide films, and polyetherimide films. The above-mentioned films may be multilayer films combining two or more types, and may have surfaces treated with a release agent such as a silicone-based release agent. The thickness of the substrate film is preferably 10 μm or more and 100 μm or less.

[0122] The thickness of the heat dissipation sheet formed on the base film is preferably 20 μm to 500 μm, more preferably 50 μm to 200 μm. A thickness of 20 μm or more allows for a heat dissipation sheet with a uniform composition, while a thickness of 500 μm or less allows for good heat dissipation.

[0123] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0124] [Weight-Average Molecular Weight] The weight-average molecular weights of compound (A) and the surface treatment agent were measured by matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS). Specifically, the measurement was performed using an "Autoflex (registered trademark) max" (manufactured by Bruker Japan) as a measuring device and a tetrahydrofuran solution containing 1 mol / L of sodium trifluoroacetate as an ionization reagent, with an accumulation count of 1,500.

[0125] [Amount of compound (A) and amount of surface treatment agent (g / m ２ ) )] Amount of compound (A) and amount of surface treatment agent (g / m ２ The specific surface area was determined by dividing the amount of compound (A) used in the examples or the amount (g) of the surface treatment agent used in the comparative examples by the BET specific surface area of ​​the particles measured by the BET single-point method using nitrogen adsorption using a specific surface area measuring device (manufactured by Mountec Co., Ltd., product name: Macsorb HM model-1210). The adsorbed gases used in measuring the specific surface area were 70% by volume of He and N. ２The particles refer to the particles used when forming the coating (a), and include aluminum nitride particles, particles containing a silicon-containing oxide coating (b) and aluminum nitride particles, particles containing an organosilicon compound coating (c) and aluminum nitride particles, or particles containing a silicon-containing oxide coating (b), an organosilicon compound coating (c), and aluminum nitride particles.

[0126] [Viscosity] The viscosity of the resin composition was measured using a flow tester (manufactured by Shimadzu Corporation, model name: "CFT-EX") under the conditions of a nozzle diameter of 2 mm and 2 mmL, at 30°C and a load of 25 kg.

[0127] [Thermal Conductivity] 20.00 g of the aluminum nitride fillers obtained in Examples 1 to 11 and Comparative Examples 6 to 11, or the aluminum nitride particles used in Comparative Example 1, or the particles obtained in Comparative Examples 2 to 5, 4.74 g of bisphenol A-type epoxy resin (trade name: YD-128, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), and 0.02 g of 2-ethyl-4-methylimidazole (trade name: 2E4MZ, manufactured by Shikoku Chemicals Corporation) as a curing agent were weighed into a container (300 mL capacity) for a planetary centrifugal mixer (trade name: Awatori Rentaro, atmospheric pressure type, ARE-310, manufactured by Thinky Corporation), and the mixture was stirred at 2000 rpm for 30 seconds using the planetary centrifugal mixer. This was then mixed manually twice to prepare a raw material for pressing. This press raw material was filled into a 30 mm x 30 mm x 0.3 mm mold, and then sandwiched between 30 μm thick copper foil on both the upper and lower surfaces, and sandwiched between 5 mm thick SUS flat plates on the sides. The mixture was press-molded at 150 ° C for 30 minutes to produce a flat plate sample with a solid volume ratio of 60% by volume. A 10 mm x 10 mm sample was cut out from this flat plate to serve as a measurement sample. Subsequently, the thermal diffusivity of the obtained measurement sample was measured using a xenon laser flash thermal diffusivity measurement device (trade name: LFA447 NanoFlash, manufactured by NETZSCH). The value calculated by multiplying the obtained thermal diffusivity by the theoretical values ​​of the specific heat and density of each measurement sample was used to determine the thermal conductivity in the thickness direction of the measurement sample.

[0128] [Materials] Table 1 shows details of the aluminum nitride particles used in the examples and comparative examples, and Table 2 shows details of the compounds used to form the coating and the compounds used to evaluate the adhesive strength.

[0129]

[0130]

[0131] Details of the alumina particles and epoxy resins used in the examples and comparative examples are as follows: AA-3: High-purity alumina (trade name: Advanced Alumina AA-3, manufactured by Sumitomo Chemical Co., Ltd., D50 = 0.40 μm) AKP-30: High-purity alumina (trade name: AKP series AKP-15, manufactured by Sumitomo Chemical Co., Ltd., D50 = 0.26 μm) Epoxy resin YD-128: Bisphenol A-type epoxy resin (trade name: YD-128, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.)

[0132] Example 1 (Production of Aluminum Nitride Filler) 0.85 g of compound a (compound (A)) (the amount that results in a content of the coating (a) in the aluminum nitride filler of 1.70 parts by mass relative to 100 parts by mass of the aluminum nitride particles I = the surface area of ​​the aluminum nitride particles I per m ２ Winning 6.3 x 10 －３ A mixed solution was prepared by dissolving 100g of aluminum nitride particles I (equivalent to 100g of aluminum nitride particles I) in 5g of isopropanol. Subsequently, 50g of aluminum nitride particles I was weighed into a 500mL evaporating dish, and the mixed solution was added in three portions, with stirring and mixing each time. After these additions, stirring, and mixing were completed in approximately 3 minutes, the mixture was cured and air-dried at room temperature for 2 hours. Thereafter, the mixture was heat-treated at 120°C for 2 hours to form a coating (a), and aluminum nitride filler X-1 was obtained.

[0133] (Production of Resin Composition) 27.00 g of aluminum nitride filler X-1 and 9.99 g of epoxy resin YD-128 were weighed into a container (volume 150 mL) for a rotation-revolution mixer (product name: Awatori Rentaro Atmospheric Pressure Type ARE-310, manufactured by Thinky Corporation), and the mixture was stirred at 2000 rpm for 30 seconds using the rotation-revolution mixer, followed by manual stirring for 20 seconds using a medicine spoon. The above stirring was repeated three times to obtain resin composition X-1. The evaluation results of the physical properties of resin composition X-1 are shown in Table 3.

[0134] [Example 2] (Production of Aluminum Nitride Filler) 27.00 g of aluminum nitride particles I were uniformly spread on a stainless steel tray and allowed to stand in a large oven with a reaction vessel capacity of 250 L. Next, 340 g of organosilicon compound (1) (trade name: 2,4,6,8-tetramethylcyclotetrasiloxane, manufactured by Tokyo Chemical Industry Co., Ltd.) in which n = 4 in formula (3) was placed in a glass Petri dish and allowed to stand in the reaction vessel, and the reaction vessel was closed. Because hydrogen gas was generated by the reaction, the reaction vessel was evacuated in advance until the oxygen concentration reached the explosion limit of 8% by volume or less, and then nitrogen gas was flowed into the reaction vessel, and the internal pressure was returned to atmospheric pressure (0.1 MPa). The reaction vessel was then heated to 80°C for 7.5 hours, and the organosilicon compound (1) was vaporized, yielding particles coated with the organosilicon compound. The obtained particles coated with the organosilicon compound were placed in an alumina crucible and heated in air at 700°C for 3 hours to obtain particles X-2 containing aluminum nitride particles and one layer of silicon-containing oxide coating (b). Subsequently, a coating (a) was formed in the same manner as in Example 1, except that particles X-2 were used instead of aluminum nitride particles I, to obtain aluminum nitride filler X-2. The compound a was added in an amount such that the content of coating (a) in the aluminum nitride filler was 1.70 parts by mass per 100 parts by mass of particles X-2 (1 m of surface area of ​​particles X-2). ２ Winning 6.3 x 10 －３ g equivalent amount) was used.

[0135] (Production of Resin Composition) Resin composition X-2 was obtained in the same manner as in Example 1, except that aluminum nitride filler X-2 was used instead of aluminum nitride filler X-1. The evaluation results of the physical properties of resin composition X-2 are shown in Table 3.

[0136] Example 3 (Production of Aluminum Nitride Filler) In Example 2, one layer of silicon-containing oxide coating (b) was formed on aluminum nitride particles I, and then another layer of silicon-containing oxide coating (b) was formed on the surface of the silicon-containing oxide coating (b) by the same procedure, thereby obtaining particles X-3 containing two layers of silicon-containing oxide coating (b). Subsequently, a coating (a) was formed in the same manner as in Example 1, except that particles X-3 were used instead of aluminum nitride particles I, thereby obtaining aluminum nitride filler X-3. Note that compound a was added in an amount such that the content of coating (a) in the aluminum nitride filler was 1.70 parts by mass per 100 parts by mass of particles X-3 (1 m of surface area of ​​particles X-3). ２ Winning 6.3 x 10 －３ g equivalent amount) was used.

[0137] (Production of Resin Composition) Resin composition X-3 was obtained in the same manner as in Example 1, except that aluminum nitride filler X-3 was used instead of aluminum nitride filler X-1. The evaluation results of the physical properties of resin composition X-3 are shown in Table 3.

[0138] Example 4 (Production of Aluminum Nitride Filler) 11.0 g of organosilicon compound (1) was placed in a φ50 glass Petri dish at the bottom of an 8 L SUS pressure vessel. Next, 200 g of aluminum nitride particles I were placed in an aluminum foil tray and placed on a SUS raised-bottom rack at the top of the 8 L SUS pressure vessel. The 8 L pressure vessel was then capped and placed in a sealed oven maintained at 80°C for 10 minutes. After depressurization, the vessel was again placed in a sealed oven maintained at 80°C for 4.5 hours for CVD treatment. Next, 200 g of 1N aqueous ammonia was placed in a 1 L polyethylene wide-mouth bottle, and the entire CVD-treated sample was added. The mixture was manually stirred every hour for the first 3 hours, and then placed in a local exhaust system at room temperature for 24 hours. The container was left unsealed during the storage period, allowing the generated hydrogen to leak through the gaps in the lid. After 24 hours, the mixture was subjected to vacuum filtration using filter paper having a roughness sufficient to retain the particle size, and the filtered cake was washed twice with distilled water and twice with ethanol. The cake was then dried at 90°C for 2 hours to form an organosilicon compound coating (c) having silanol groups, thereby obtaining particles X-4 containing the organosilicon compound coating (c). Subsequently, a coating (a) was formed in the same manner as in Example 1, except that particles X-4 were used instead of aluminum nitride particles I, thereby obtaining aluminum nitride filler X-4. The compound a was added in an amount such that the content of the coating (a) in the aluminum nitride filler was 1.70 parts by mass per 100 parts by mass of particles X-4 (1 m of surface area of ​​particles X-4). ２ Winning 6.3 x 10 －３ g equivalent amount) was used.

[0139] (Production of Resin Composition) Resin composition X-4 was obtained in the same manner as in Example 1, except that aluminum nitride filler X-4 was used instead of aluminum nitride filler X-1. The evaluation results of the physical properties of resin composition X-4 are shown in Table 3.

[0140] Example 5 (Production of Aluminum Nitride Filler) Particles X-2 containing one layer of silicon-containing oxide coating (b) were obtained in the same manner as in Example 2. Subsequently, an organosilicon compound coating (c) having a silanol group was formed in the same manner as in Example 4, except that particles X-2 were used instead of aluminum nitride particles I, to obtain particles X-5 containing the organosilicon compound coating (c). Subsequently, a coating (a) was formed in the same manner as in Example 1, except that particles X-5 were used instead of aluminum nitride particles I, to obtain aluminum nitride filler X-5. The compound a was added in an amount such that the content of the coating (a) in the aluminum nitride filler was 1.70 parts by mass per 100 parts by mass of particles X-5 (1 m of surface area of ​​particles X-5). ２ Winning 6.3 x 10 －３ g equivalent amount) was used.

[0141] (Production of Resin Composition) Resin composition X-5 was obtained in the same manner as in Example 1, except that aluminum nitride filler X-5 was used instead of aluminum nitride filler X-1. The evaluation results of the physical properties of resin composition X-5 are shown in Table 3.

[0142] Example 6 (Production of Aluminum Nitride Filler) Particles X-3 containing two layers of silicon-containing oxide coating (b) were obtained in the same manner as in Example 3. Subsequently, an organosilicon compound coating (c) having a silanol group was formed in the same manner as in Example 4, except that particles X-3 were used instead of aluminum nitride particles I, to obtain particles X-6 containing the organosilicon compound coating (c). Subsequently, a coating (a) was formed in the same manner as in Example 1, except that particles X-6 were used instead of aluminum nitride particles I, to obtain aluminum nitride filler X-6. Compound a was added in an amount such that the content of coating (a) in the aluminum nitride filler was 1.70 parts by mass per 100 parts by mass of particles X-6 (the surface area of ​​particles X-6 was 1 m ２ Winning 6.3 x 10 －３ g equivalent amount) was used.

[0143] (Production of Resin Composition) Resin composition X-6 was obtained in the same manner as in Example 1, except that aluminum nitride filler X-6 was used instead of aluminum nitride filler X-1. The evaluation results of the physical properties of resin composition X-6 are shown in Table 3.

[0144] [Example 7] (Production of Aluminum Nitride Filler) In Example 2, instead of using 0.85 g of compound a, 0.25 g (an amount such that the content of the coating (a) in the aluminum nitride filler is 0.50 parts by mass relative to 100 parts by mass of particles X-2 = 1 m of surface area of ​​particles X-2) was used. ２ Winning 1.9 x 10 －３ In the same manner as above, except that aluminum nitride filler X-7 was used (corresponding to 1000g of aluminum nitride).

[0145] (Production of Resin Composition) Resin composition X-7 was obtained in the same manner as in Example 1, except that aluminum nitride filler X-7 was used instead of aluminum nitride filler X-1. The evaluation results of the physical properties of resin composition X-7 are shown in Table 3.

[0146] [Example 8] (Production of Aluminum Nitride Filler) Particles X-8 were obtained by using aluminum nitride particles II instead of aluminum nitride particles I in Example 2. Subsequently, instead of using 0.85 g of compound a in Example 1, 0.15 g of compound b (compound (A)) was used (the amount such that the content of coating (a) in the aluminum nitride filler is 0.30 parts by mass per 100 parts by mass of particles X-8 = the amount equivalent to 1 m of the surface area of ​​particles X-8). ２ 1.2 x 10 －２ A coating (a) was formed in the same manner as above, except that particles X-8 were used instead of aluminum nitride particles I, to obtain aluminum nitride filler X-8.

[0147] (Production of Resin Composition) 20.00 g of aluminum nitride filler X-8, 12.50 g of AA-3, 10.00 g of AKP-30, and 2.50 g of epoxy resin YD-128 were weighed into a container (volume 150 mL) for a rotation / revolution mixer (product name: Awatori Rentaro Atmospheric Pressure Type ARE-310, manufactured by Thinky Corporation), and the mixture was stirred at 2000 rpm for 30 seconds using the rotation / revolution mixer, followed by manual stirring for 20 seconds using a medicine spoon. The above stirring was performed three times to obtain resin composition X-8. The evaluation results of the physical properties of resin composition X-8 are shown in Table 3.

[0148] Example 9 (Production of Aluminum Nitride Filler) Particles X-8 were obtained by the same procedure as in Example 8. Subsequently, an organosilicon compound coating (c) having a silanol group was formed in the same manner as in Example 4, except that particles X-8 were used instead of aluminum nitride particles I, to obtain particles X-9 containing the organosilicon compound coating (c). Subsequently, a coating (a) was formed in the same manner as in Example 8, except that particles X-9 were used instead of aluminum nitride particles I, to obtain aluminum nitride filler X-9. The compound a was added in an amount such that the content of the coating (a) in the aluminum nitride filler was 0.30 parts by mass per 100 parts by mass of particles X-9 (per 1 m of surface area of ​​particles X-9). ２ 1.2 x 10 －２ g equivalent amount) was used.

[0149] (Production of Resin Composition) Resin composition X-9 was obtained in the same manner as in Example 8, except that aluminum nitride filler X-9 was used instead of aluminum nitride filler X-8. The evaluation results of the physical properties of resin composition X-9 are shown in Table 3.

[0150] [Example 10] (Production of Aluminum Nitride Filler) In Example 1, 0.10 g of compound a (an amount such that the content of the coating (a) in the aluminum nitride filler is 0.20 parts by mass per 100 parts by mass of aluminum nitride III = 1 m of surface area of ​​aluminum nitride III) was used. ２ Winning 2.9 x 10 －２The aluminum nitride filler X-10 was obtained in the same manner as above, except that aluminum nitride particles III were used instead of aluminum nitride particles I to form the coating (a).

[0151] (Production of Resin Composition) Resin composition X-10 was obtained in the same manner as in Example 8, except that 17.62 g of aluminum nitride filler X-10 was used instead of aluminum nitride filler X-8, and 11.10 g of AA-3, 9.08 g of AKP-30, and 2.16 g of epoxy resin YD-128 were used. The evaluation results of the physical properties of resin composition X-10 are shown in Table 3.

[0152] [Example 11] (Production of Aluminum Nitride Filler) In Example 4, 0.10 g of compound a (an amount such that the content of the coating (a) in the aluminum nitride filler is 0.20 parts by mass per 100 parts by mass of aluminum nitride III = 1 m of surface area of ​​aluminum nitride III) was used. ２ Winning 2.9 x 10 －２ The aluminum nitride filler X-11 was obtained in the same manner as above, except that aluminum nitride particles III were used instead of aluminum nitride particles I to form the coating (a).

[0153] (Production of Resin Composition) Resin composition X-11 was obtained in the same manner as in Example 10, except that aluminum nitride filler X-11 was used instead of aluminum nitride filler X-10. The evaluation results of the physical properties of resin composition X-11 are shown in Table 3.

[0154] Example 12 9.99 g of epoxy resin YD-128 and 0.06 g of compound a (an amount such that the content of the coating (a) in the aluminum nitride filler is 0.22 parts by mass per 100 parts by mass of aluminum nitride I = 1 m of surface area of ​​aluminum nitride I) were mixed. ２ Winning 8.0 x 10 －４The resulting mixture (equivalent to 1000 g of aluminum nitride particles I) was weighed out and placed in a container (150 mL capacity) for a planetary centrifugal mixer (product name: THINKY MIXER, atmospheric pressure type, ARE-310, manufactured by THINKY CORPORATION), and stirred at 2000 rpm for 30 seconds using the planetary centrifugal mixer. 27.00 g of aluminum nitride particles I was then added, and stirring at 2000 rpm for 30 seconds was repeated three times to obtain resin composition X-12. The evaluation results of the physical properties of resin composition X-12 are shown in Table 3.

[0155] Example 13 Particles X-2 containing one layer of silicon-containing oxide coating (b) were obtained in the same manner as in Example 2. Subsequently, a resin composition X-13 was obtained in the same manner as in Example 12, except that particles X-2 were used instead of aluminum nitride particles I. The compound a was added in an amount such that the content of coating (a) in the aluminum nitride filler was 0.22 parts by mass per 100 parts by mass of particles X-2 (per 1 m of surface area of ​​particles X-2). ２ Winning 8.0 x 10 －４ The results of evaluation of the physical properties of resin composition X-13 are shown in Table 3.

[0156] Comparative Example 1 27.00 g of aluminum nitride particles I and 9.99 g of epoxy resin YD-128 were weighed into a container (150 mL capacity) for a rotation-revolution mixer (product name: Awatori Rentaro Atmospheric Pressure Type ARE-310, manufactured by Thinky Corporation), and the mixture was stirred at 2000 rpm for 30 seconds using the rotation-revolution mixer, followed by manual stirring for 20 seconds using a medicine spoon. The stirring was repeated three times to obtain resin composition Y-1. The evaluation results of the physical properties of resin composition Y-1 are shown in Table 4.

[0157] Comparative Example 2 Particles X-2 containing one layer of silicon-containing oxide coating (b) were obtained in the same manner as in Example 2. Subsequently, resin composition Y-2 was obtained in the same manner as in Comparative Example 1, except that particles X-2 were used instead of aluminum nitride particles I. The evaluation results of the physical properties of resin composition Y-2 are shown in Table 4.

[0158] Comparative Example 3 Particles X-3 containing two silicon-containing oxide coatings (b) were obtained in the same manner as in Example 3. Subsequently, resin composition Y-3 was obtained in the same manner as in Comparative Example 1, except that particles X-3 were used instead of aluminum nitride particles I. The evaluation results of the physical properties of resin composition Y-3 are shown in Table 4.

[0159] Comparative Example 4 Particles X-8 containing one layer of silicon-containing oxide coating (b) were obtained in the same manner as in Example 8. Subsequently, 20.00 g of particles X-8, 12.50 g of AA-3, 10.00 g of AKP-30, and 2.50 g of epoxy resin YD-128 were weighed into a container (150 mL capacity) for a rotation-revolution mixer (product name: Awatori Rentaro Atmospheric Pressure Type ARE-310, manufactured by Thinky Corporation). The mixture was stirred at 2000 rpm for 30 seconds using the rotation-revolution mixer, and then manually stirred for 20 seconds using a medicine spoon. The above stirring was repeated three times to obtain resin composition Y-4. The evaluation results of the physical properties of resin composition Y-4 are shown in Table 4.

[0160] Comparative Example 5 Particles Y-1 were obtained by forming one layer of silicon-containing oxide coating (b) in the same manner as in Example 2, except that aluminum nitride particles III were used instead of aluminum nitride particles I. Subsequently, 17.62 g of particles Y-1, 11.10 g of AA-3, 9.08 g of AKP-30, and 2.16 g of epoxy resin YD-128 were weighed into a container (150 mL capacity) for a rotation-revolution mixer (product name: Awatori Rentaro Atmospheric Pressure Type ARE-310, manufactured by Thinky Corporation). The mixture was stirred at 2000 rpm for 30 seconds using the rotation-revolution mixer, and then manually stirred for 20 seconds using a medicine spoon. The above stirring was repeated three times to obtain resin composition Y-5. The evaluation results of the physical properties of resin composition Y-5 are shown in Table 4.

[0161] Comparative Examples 6 to 11 Particles X-2 containing one layer of silicon-containing oxide coating (b) were obtained in Example 2. Subsequently, instead of using compound a in Example 2, 0.85 g of compounds c to h (surface treatment agents) other than compound (A) shown in Table 4 were added (an amount such that the content of coating (a′) (coating made of surface treatment agent) in the aluminum nitride filler was 1.70 parts by mass per 100 parts by mass of particles X-2 = an amount equivalent to 1 m of the surface area of ​​particles X-2). ２ Winning 6.3 x 10 －３ Aluminum nitride fillers Y-6 to Y-11 were obtained in the same manner as in Comparative Example 1, except that aluminum nitride fillers Y-6 to Y-11 were used instead of aluminum nitride particles I. Subsequently, resin compositions Y-6 to Y-11 were obtained in the same manner as in Comparative Example 1, except that aluminum nitride fillers Y-6 to Y-11 were used instead of aluminum nitride particles I. The evaluation results of the physical properties of resin compositions Y-6 to Y-11 are shown in Table 4.

[0162] Comparative Example 12 In Example 13, instead of using compound a, 0.06 g of compound g (surface treatment agent) was used (an amount such that the content of coating (a′) (coating made of surface treatment agent) in the aluminum nitride filler was 0.22 parts by mass per 100 parts by mass of particles X-2 = 1 m of surface area of ​​particles X-2). ２ Winning 8.0 x 10 －４ Aluminum nitride filler Y-12 was obtained in the same manner as above, except that an amount equivalent to 1000g of aluminum nitride was used instead of the above-mentioned filler Y-12, and then resin composition Y-12 was obtained. The evaluation results of the physical properties of resin composition Y-12 are shown in Table 4.

[0163]

[0164]

[0165] From Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, Example 8 and Comparative Example 4, and Example 10 and Comparative Example 5, it can be seen that by including a coating (a) containing compound (A) in an aluminum nitride filler, it is possible to suppress an increase in viscosity when mixed with an epoxy resin. Furthermore, it can be seen that Comparative Examples 6 to 12, which used compounds c to h that do not have a polyethyleneimine skeleton and a polyalkylene oxide chain and have a weight-average molecular weight of 2,000 to 10,000, show an increase in viscosity when mixed with an epoxy resin. Furthermore, it can be seen from Examples 1 to 11 and Comparative Examples 1 to 11 that the coating (a) containing compound (A) does not impair the inherent high thermal conductivity of aluminum nitride.

[0166] [Adhesive Strength] 1.25 g of an epoxy resin (trade name: EPPN-502H, manufactured by Nippon Kayaku Co., Ltd.), 1.25 g of a liquid high-purity epoxy resin (trade name: ZX-1059, manufactured by Nippon Steel Chemical & Material Co., Ltd.), 0.02 g of triphenylphosphine (reaction accelerator), 1.90 g of cyclohexanone, and 0.06 g of compound a were placed in a container (volume 150 mL) for a rotation-revolution mixer (manufactured by Thinky Corporation, trade name: Awatori Rentaro, atmospheric pressure type ARE-310), and the mixture was mixed and stirred once for 30 seconds at a rotation speed of 2000 rpm using the rotation-revolution mixer, to obtain a resin composition. To this was added 20.00 g of highly thermally conductive AlN filler (trade name: FAN-f50-A1, manufactured by Furukawa Denshi Co., Ltd., D50 = 50 μm), 4.06 g of high-purity alumina (trade name: Advanced Alumina AA-3, manufactured by Sumitomo Chemical Co., Ltd., D50 = 0.40 μm), and 8.11 g of high-purity alumina (trade name: Advanced Alumina AA-4, manufactured by Sumitomo Chemical Co., Ltd., D50 = 0.47 μm), and the mixture was mixed and stirred for 30 seconds at a rotation speed of 2000 rpm for a total of three times using the rotation / revolution type mixer to obtain a slurry. The resulting slurry was applied to a 12 μm-thick copper foil using an applicator with a coating gap of 350 μm. After drying at 100°C for 10 minutes, a 12 μm-thick copper foil was placed on top of the coated foil, which was then sandwiched between 38 μm polyester sheets to form a pre-press sheet. This was pressed at 180°C for 1 hour at a pressure of 5 MPa to harden it and produce a copper-clad board. Next, the polyester sheet was removed, and 10 mm-wide PET adhesive masking tape was firmly attached to the copper foil, leaving a 2-3 mm gap. This was immersed in a 9% aqueous sodium peroxide solution at 75°C for 60 minutes to dissolve the copper, then removed and thoroughly washed with distilled water. The moisture was wiped off with a laboratory wiper, and the foil was air-dried to create a 10 mm-wide strip. The PET adhesive masking tape was peeled off to prepare a peel test specimen. One end of the copper foil of the peel test piece was peeled off, and a 90-degree peeling jig was set on a desktop precision universal testing machine "Autograph AGS-X" (manufactured by Shimadzu Corporation), and the adhesive strength was measured at a peeling rate of 50 mm / min. The results are shown in Table 5. Table 5 also shows the results of measuring the adhesive strength when compounds b to g were used instead of compound a, and when compound a was not used.When compounds d to f were used, the dried slurry did not adhere to the copper foil, and the adhesive strength could not be measured.

[0167]

[0168] The results in Table 5 show that a resin composition containing either compound a or b, which is compound (A), and an epoxy resin has good adhesive strength. Therefore, it is presumed that a resin composition containing an aluminum nitride filler containing a coating (a) containing compound (A) and an epoxy resin also has good adhesive strength.

Claims

1. An aluminum nitride filler comprising aluminum nitride particles and a coating (a) containing a compound (A) having a polyethyleneimine skeleton and a polyalkylene oxide chain and having a weight average molecular weight of 2,000 or more and 10,000 or less.

2. The aluminum nitride filler according to claim 1, which contains a silicon-containing oxide coating (b).

3. The aluminum nitride filler according to claim 1 or 2, which contains a coating (c) of an organosilicon compound having a silanol group.

4. The aluminum nitride filler according to claim 3, wherein the coating (a) and the organosilicon compound coating (c) are adjacent to each other.

5. The specific surface area (m) of the aluminum nitride particles determined by the BET method ２ / g) ２ The compound (A) is added at 5.0×10 -4 g or more 5.0×10 -2 2. The aluminum nitride filler of claim 1, comprising less than 1 g.

6. The specific surface area (m2) of the particles containing the silicon-containing oxide film (b) and the aluminum nitride particles, determined by the BET method ２ / g) ２ The compound (A) is added at 5.0×10 -４ g or more 5.0×10 -２ 3. The aluminum nitride filler of claim 2, comprising less than 1 g.

7. The specific surface area (m2) of the particles containing the silanol group-containing organosilicon compound coating (c) and the aluminum nitride particles, determined by the BET method. ２ / g) ２ The compound (A) is added at 5.0×10 -４ g or more 5.0×10 -２ 4. The aluminum nitride filler of claim 3, comprising less than 1 g.

8. The specific surface area (m2) of the particles containing the silicon-containing oxide coating (b), the silanol group-containing organosilicon compound coating (c), and the aluminum nitride particles, determined by the BET method. ２ / g) ２ The compound (A) is added at 5.0×10 -4 g or more 5.0×10 -2 4. The aluminum nitride filler of claim 3, comprising less than 1 g.

9. A method for producing an aluminum nitride filler comprising aluminum nitride particles and a coating (a) containing a compound (A) having a polyethyleneimine skeleton and a polyalkylene oxide chain and a weight average molecular weight of 2,000 or more and 10,000 or less, the method comprising a fourth step of forming the coating (a).

10. A method for producing an aluminum nitride filler according to claim 9, comprising: a first step of coating with an organosilicon compound having active hydrogen; and a second step of forming a silicon-containing oxide coating film (b) by heating.

11. A method for producing an aluminum nitride filler as described in claim 9 or 10, comprising a third step of coating an organosilicon compound having active hydrogen by vapor deposition, and treating the coated organosilicon compound with a basic substance to form an organosilicon compound coating (c) having a silanol group.

12. A resin composition comprising the aluminum nitride filler according to claim 1 or 2 and an epoxy resin.

13. A method for producing a resin composition according to claim 12, comprising step I of adding and mixing said aluminum nitride filler into said epoxy resin.

14. A method for producing a resin composition according to claim 12, comprising: a step II-1 of obtaining a composition i containing the compound (A) and the epoxy resin; and a step II-2 of adding to and mixing with the composition i at least one type of particle selected from aluminum nitride particles, particles containing a silicon-containing oxide coating (b) and aluminum nitride particles, particles containing an organosilicone compound coating (c) and aluminum nitride particles, and particles containing a silicon-containing oxide coating (b), an organosilicone compound coating (c), and aluminum nitride particles.

Images