Method for producing nitride filler coated with organosilicon-containing compound having silanol groups, and method for producing silica-coated nitride filler coated with organosilicon-containing compound having silanol groups

Abstract

Provided are a method for producing a nitride filler coated with an organosilicon-containing compound and having a silanol group and a method for producing a silica-coated nitride filler coated with an organosilicon-containing compound and having a silanol group, with which it becomes possible to control the reduction in viscosity of a slurry obtained by mixing with a resin monomer.　The method for producing a nitride filler coated with an organosilicon-containing compound and having a silanol group includes: a step 1A in which the surface of a nitride filler is coated with an organic silicone compound containing a specific structure to produce a nitride filler coated with an organosilicon-containing compound; and a step 2A in which the surface of the nitride filler coated with an organosilicon-containing compound is treated with a specific basic substance to produce a nitride filler coated with an organosilicon-containing compound and having a silanol group on the surface thereof. Alternatively, the method includes a step 1P in which the surface of a nitride filler is coated by treating the nitride filler with an organic silicone compound and a basic substance simultaneously while allowing both of the organic silicone compound and the basic substance to coexist in the same atmosphere, thereby producing a nitride filler coated with an organosilicon-containing compound and having a silanol group on the surface thereof.

Description

[Technical Field]

[0001] The present invention relates to a nitride filler coated with an organosilicon-containing compound having silanol groups and a method for producing the same, and to a silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups and a method for producing the same. [Background technology]

[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 moisture to undergo hydrolysis, transforming into aluminum hydroxide, which has low thermal conductivity. Furthermore, aluminum nitride generates corrosive ammonia during hydrolysis.

[0003] The hydrolysis of aluminum nitride also progresses due to moisture in the atmosphere. Therefore, products containing aluminum nitride may not only experience a decrease in moisture resistance and thermal conductivity under high temperature and humidity conditions, but may also experience corrosion due to the ammonia generated by the hydrolysis of aluminum nitride, raising concerns about performance degradation.

[0004] Techniques for improving the moisture resistance of aluminum nitride include a method of forming a layer made of Si-Al-ON 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).

[0005] The moisture-proof aluminum nitride powder of Patent Document 1 is produced 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 made of Si-Al-ON on the surface. The aluminum nitride powder of Patent Document 2 is surface-treated 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 surface-treated with a silicate treatment agent, followed by heat treatment at a temperature not exceeding 90°C, which leaves organic groups and improves compatibility with resins. The surface-modified particles in Patent Document 4 are aluminum nitride particles whose surface has been modified with a specific acidic phosphate ester, thereby improving moisture resistance. The surface-modified particles in Patent Document 5 are aluminum nitride particles with excellent moisture resistance that are coated with an extremely thin, uniform, and dense silica film.

[0006] 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 also being developed for a variety of applications due to 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, it can have problems with compatibility with resins and can easily result in high slurry viscosity. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 3446053 [Patent Document 2] Patent No. 4088768 [Patent Document 3] Patent No. 4804023 [Patent Document 4] Japanese Patent Application Laid-Open No. 2015-71730 [Patent Document 5] International Publication No. 2020 / 040309 Summary of the Invention [Problem to be solved by the invention]

[0008] However, aluminum nitride powder or moisture-resistant silica-coated aluminum nitride powder has problems with compatibility with silicone resins and reducing the viscosity of silicone monomer slurries. Further improvement in compatibility is required, particularly when attempting to compound aluminum nitride powder at high loadings. In particular, in the case of Patent Document 5, which can maintain high thermal conductivity and achieve excellent moisture resistance, a further reduction in the slurry viscosity is required. Furthermore, because the primary particles of boron nitride are plate-shaped, the slurry viscosity increases significantly, especially at high filling rates, and silane coupling agent treatment using standard processes does not achieve sufficient slurry viscosity reduction. In other words, the true value of a heat-dissipating filler is evaluated based on the product of two properties: the thermal properties of the powder itself and how highly it can be loaded into resin while maintaining moldability. Therefore, the slurry viscosity reduction effect is a property that is just as important as thermal properties.

[0009] The present invention has been made in view of the above circumstances, and aims to provide a method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups, which makes it possible to control the reduction in the viscosity of the slurry obtained by mixing with a resin monomer, and a method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups. [Means for solving the problem]

[0010] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by using a specific organosilicone compound and a specific basic substance and coating them on the surface of a nitride filler or a silica-coated nitride filler by a specific method, and have completed the present invention. That is, the present invention has the following features.

[0011] [1] A method for producing a nitride filler coated with an organosilicon-containing compound having a silanol group, comprising: a nitride filler; and an organosilicon-containing compound coating film covering the surface of the nitride filler and having a silanol group on the surface, The method includes a step 1A of covering the surface of the nitride filler with an organosilicon compound having a structure represented by the following general formula (1) to obtain an organosilicon-containing compound-coated nitride filler covered with the organosilicon compound, and a step 2A of treating the surface of the organosilicon-containing compound-coated nitride filler with a basic substance to obtain an organosilicon-containing compound-coated nitride filler having silanol groups on the surface, or A method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups, comprising a first process P in which an organosilicon compound having a structure represented by the following general formula (1) and a basic substance are allowed to coexist in the same atmosphere, the organosilicon compound and the basic substance are treated simultaneously, and the surface of the nitride filler is covered, thereby obtaining an organosilicon-containing compound-coated nitride filler having silanol groups on the surface. [ka] (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.) [2] The method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to [1] above, wherein in step 2A, the basic substance is aqueous ammonia, and the treatment is carried out by immersion in the aqueous ammonia. [3] The method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to [1] above, wherein in step 2A, the basic substance is aqueous ammonia, and the treatment is carried out by chemical vapor deposition (CVD). [4] The method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to the above [1], wherein in the first step P, the basic substance is aqueous ammonia, and the treatment is carried out simultaneously with the organosilicon compound by chemical vapor deposition (CVD). [5] The method for producing a nitride filler coated with an organosilicon-containing compound having a silanol group according to any one of [1] to [4] above, wherein the nitride filler is aluminum nitride particles or boron nitride particles. [6] A method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to the above [5], wherein the aluminum nitride particles have a particle size (D50) of 50% of the cumulative volume of 0.1 μm or more and 200 μm or less. [7] A method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to any one of the above [1] to [6], in which a surface treatment agent is attached to the surface of the nitride filler coated with an organosilicon-containing compound having silanol groups by reaction or interaction. [8] The method for producing a nitride filler coated with an organosilicon-containing compound having a silanol group according to [7] above, wherein the surface treatment agent is a silane coupling agent. [9] A nitride filler and a surface of the nitride filler that covers the surface and has a density of 0.5 to 2.1 particles / nm 2 and a coating of an organosilicon-containing compound having silanol groups present at an average surface density of 1000 to 15000.

[10] The nitride filler coated with an organosilicon-containing compound having silanol groups according to [9] above, further comprising a surface treatment agent on the surface of the nitride filler coated with an organosilicon-containing compound having silanol groups.

[11] The nitride filler coated with an organosilicon-containing compound having a silanol group according to the above

[10] , wherein the surface treatment agent is a silane coupling agent.

[12] A method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group, comprising: a silica-coated nitride filler; and an organosilicon-containing compound coating film covering the surface of the silica-coated nitride filler and having a silanol group on the surface, the method comprising: The method comprises a step 1B of covering the surface of the silica-coated nitride filler with an organosilicon compound having a structure represented by the following general formula (1) to obtain an organosilicon-containing compound-coated silica-coated nitride filler coated with the organosilicon compound, and a step 2B of treating the surface of the organosilicon-containing compound-coated silica-coated nitride filler with a basic substance to obtain an organosilicon-containing compound-coated silica-coated nitride filler having silanol groups on its surface: Or, A method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups, comprising step 1Q of simultaneously treating an organosilicon compound having a structure represented by the following general formula (1) with a basic substance in the same atmosphere to coat the surface of the silica-coated nitride filler and obtain a silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups on the surface. [ka] (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.)

[13] The method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to

[12] above, wherein in step 2B, the basic substance is aqueous ammonia, and the treatment is carried out by immersion in the aqueous ammonia.

[14] The method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to

[12] above, wherein in step 2B, the basic substance is aqueous ammonia, and the treatment is carried out by a chemical vapor deposition (CVD) method.

[15] A method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to

[12] above, wherein in step 1Q, the basic substance is aqueous ammonia, and the treatment is carried out simultaneously with the organosilicon compound by chemical vapor deposition (CVD).

[16] The method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to any one of

[12] to

[15] above, wherein the nitride filler is aluminum nitride particles or boron nitride particles.

[17] A method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to the above

[16] , wherein the 50% cumulative volume particle size (D50) of the aluminum nitride particles is 0.1 μm or more and 200 μm or less.

[18] A method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to any one of the above

[12] to

[17] , in which a surface treatment agent is attached to the surface of the silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group by reaction or interaction.

[19] The method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to

[18] above, wherein the surface treatment agent is a silane coupling agent.

[20] A silica-coated nitride filler, and a silica-coated nitride filler having a surface covering the silica-coated nitride filler and a density of 0.5 to 2.1 particles / nm 2 and a coating of an organosilicon-containing compound having silanol groups present at an average surface density of 1000 to 15000.

[21] The silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to

[20] above, further comprising a surface treatment agent on the surface of the silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group.

[22] The silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to

[21] above, wherein the surface treatment agent is a silane coupling agent. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups, and a method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups, which makes it possible to control the reduction in the viscosity of the slurry obtained by mixing with a resin monomer. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below. The present invention also includes any selected or combined embodiment of the matters described in this specification. In this specification, preferred definitions can be selected arbitrarily, and combinations of preferred definitions can be considered more preferred. 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.), the 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 film formation methods in the "gas film formation method" and "gas simultaneous film formation method" relating to the treatment of basic substances include film formation methods by chemical vapor deposition (CVD).

[0015] 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 can be 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.

[0016] <Method for producing nitride filler coated with organosilicon-containing compound having silanol groups> The method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups of the present invention comprises a nitride filler and an organosilicon-containing compound coating film covering the surface of the nitride filler and having silanol groups on the surface thereof, and includes the steps of: The method includes a step 1A of covering the surface of the nitride filler with an organosilicon compound having a structure represented by the following general formula (1) to obtain an organosilicon-containing compound-coated nitride filler covered with the organosilicon compound, and a step 2A of treating the surface of the organosilicon-containing compound-coated nitride filler with a basic substance to obtain an organosilicon-containing compound-coated nitride filler having silanol groups on its surface: Or, The method is characterized by including a first process P in which an organosilicon compound having a structure represented by the following general formula (1) and a basic substance are allowed to coexist in the same atmosphere, the organosilicon compound and the basic substance are treated simultaneously, and the surface of the nitride filler is covered, thereby obtaining an organosilicon-containing compound-coated nitride filler having silanol groups on the surface. [ka] (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.)

[0017] [1st A process] This step is a step of covering the surface of a nitride filler with an organosilicon compound containing the structure represented by the above formula (1) to obtain the nitride filler covered with the organosilicon compound.

[0018] <Nitride filler> In the method of the present invention for producing a nitride filler coated with an organosilicon-containing compound having silanol groups, examples of nitride fillers used as raw materials include aluminum nitride, boron nitride, and silicon nitride. Among these, aluminum nitride and boron nitride are preferred from the viewpoint of having high thermal conductivity and being suitable as a filler for resin compositions.

[0019] (aluminum nitride particles) In the method of producing the nitride filler coated with an organosilicon-containing compound having silanol groups 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 aluminum nitride particles is not particularly limited, and examples thereof include a direct nitridation method in which metallic aluminum powder is directly reacted with nitrogen or ammonia, and a reduction-nitridation method in which alumina is carbon-reduced while being heated in a nitrogen or ammonia atmosphere to simultaneously carry out a nitriding reaction.

[0020] 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.

[0021] Here, the 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 organosilicon-containing compound-coated aluminum nitride particles. The aluminum nitride particles can be used alone or in combination.

[0022] The oxygen content can be measured using an inorganic analyzer equipped with an infrared detector for oxygen detection. Specifically, the oxygen content can be measured using an oxygen / nitrogen / hydrogen analyzer (ONH836: manufactured by LECO Japan LLC) or the like.

[0023] 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).

[0024] 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, etc. Furthermore, when the organosilicon-containing compound-coated aluminum nitride particles are dispersed and contained in a resin composition as a filler, 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.

[0025] When aluminum nitride particles coated with an organosilicon-containing compound having silanol groups are dispersed in a resin composition, the greater the volume ratio (filling amount) of aluminum nitride particles constituting the aluminum nitride particles coated with an organosilicon-containing compound having silanol groups to the resin composition, the higher the thermal conductivity of the resin composition.Therefore, the shape of the aluminum nitride particles is preferably close to spherical, which minimizes the increase in viscosity of the resin composition due to the addition of the aluminum nitride particles coated with an organosilicon-containing compound.

[0026] The cumulative volume 50% particle size (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.

[0027] When the D50 of the aluminum nitride particles is within the above-mentioned range, even when a resin composition containing aluminum nitride particles coated with an organosilicon-containing compound is used as a heat dissipation material to be mounted on power electronic components, it becomes possible to provide a thin heat dissipation material with a minimum thickness, and the moisture resistance of the aluminum nitride particles is further improved, probably because the coating easily coats the surface of the aluminum nitride particles uniformly.

[0028] (boron nitride particles) In the method of producing a nitride filler coated with an organosilicon-containing compound having silanol groups of the present invention, the boron nitride particles used as a raw material can be any known product, such as a commercially available product. There are no particular limitations on the method for producing boron nitride particles, and examples include (a) a method of directly nitriding boron using nitrogen, ammonia, etc., (b) a method of reacting a boron halide with ammonia or an ammonium salt, (c) a method of reducing and nitriding a boron compound such as boric acid or boron oxide by reacting it with a nitrogen-containing compound such as melamine at a temperature of about 800°C, and (d) a method of reducing and nitriding a boron compound by heating a boron compound and a carbon source to a high temperature of 1600°C or higher in a nitrogen atmosphere. Of these, method (d) can use low-cost raw materials and is the most preferred method for producing boron nitride. For example, commercially available products include UHP-1K (manufactured by Resonac, Inc., D50: 8.5 μm), UHP-2 (manufactured by Resonac, Inc., D50: 10.5 μm), and UHP-S2 (manufactured by Resonac, Inc., D50: 1.0 μm).

[0029] <Organic silicone compounds used for coating> In the method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups of the present invention, the organosilicon compound used as a raw material for the organosilicon-containing compound coating that constitutes the nitride filler coated with an organosilicon-containing compound having silanol groups is an organosilicon compound having a structure represented by the above formula (1). It can be used without particular restrictions, regardless of whether it is linear, cyclic, or branched. The structure represented by formula (1) is a hydrogensiloxane unit in which hydrogen is directly bonded to a silicon atom.

[0030] In the above 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 method of producing an organosilicon-containing compound-coated nitride filler having silanol groups of the present invention, the organosilicon compound used as a raw material is, for example, an oligomer or polymer containing the structure represented by formula (1).

[0031] 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. [ka] (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.)

[0032] [ka] (In formula (3), n is an integer of 3 to 6.)

[0033] In particular, a cyclic hydrogensiloxane oligomer in which n is 4 in the above formula (3) is excellent in that it can form a uniform coating on the surface of aluminum nitride particles. The weight-average molecular weight of the organosilicone compound containing the structure shown in formula (1) is preferably 100 or more and 2000 or less, more preferably 150 or more and 1000 or less, and even more preferably 180 or more and 500 or less. It is presumed that by using an organosilicone compound containing the structure shown in formula (1) with a weight-average molecular weight within this range, it is easy to form a thin and uniform coating on the surface of the nitride filler.

[0034] In this specification, the weight-average molecular weight is a weight-average molecular weight in terms of polystyrene measured using gel permeation chromatography (GPC), and specifically, it can be measured using a combination of a column (Shodex (registered trademark) LF-804, manufactured by Resonac Corporation) and a differential refractive index detector (Shodex (registered trademark) RI-71S, manufactured by Resonac Corporation).

[0035] In step 1A, the surface of the nitride filler is covered with an organosilicone compound containing the structure represented by formula (1) above. In Step 1A, the method is not particularly limited as long as the surface of the nitride filler can be coated with an organosilicon compound having the structure represented by Formula (1). Examples of methods for Step 1A include a dry mixing method in which an organosilicon compound is added to the raw nitride filler by spraying or other means while stirring the nitride filler, followed by dry mixing to coat the nitride filler. 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 magnetically coupled stirrer in a sealed container. The temperature conditions in this case are not particularly limited, depending on the boiling point and vapor pressure of the silicone compound having the structure represented by Formula (1). A preferred temperature is 10°C to 200°C, more preferably 20°C to 150°C, and even more preferably 40°C to 100°C.

[0036] Alternatively, step 1A can be performed using a gas-phase adsorption method in which the vapor of an organosilicon compound having the structure represented by formula (1), either alone or in a mixture with an inert gas such as nitrogen gas, is deposited or deposited on the surface of a stationary nitride filler. The temperature conditions in this case vary depending on the boiling point and vapor pressure of the silicone compound having the structure represented by formula (1), but are preferably 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 can easily replace the gas within the system, such as a CVD apparatus using a glass container or a desiccator. If the nitride filler 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.

[0037] The amount of the organosilicon compound containing the structure represented by formula (1) used in step 1A is not particularly limited. In the nitride filler coated with the organosilicon compound containing the structure represented by formula (1) obtained in step 1A, the coating amount of the organosilicon compound containing the structure represented by formula (1) is determined by the BET method of the nitride filler. 2 / g) to calculate the surface area of ​​1m 2 The range 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. The specific surface area (m 2 / g) to calculate the surface area of ​​1m 2The coating amount of the organosilicon compound containing the structure represented by formula (1) per unit area of ​​the nitride filler was calculated by multiplying the mass difference between the nitride filler before and after coating with the organosilicon compound by the specific surface area (m2) of the nitride filler determined by the BET method. 2 Surface area (m2) calculated from 2 ) can be found by dividing by The specific surface area determined by the BET method can be measured by a nitrogen adsorption BET single-point method using a gas flow method. The evaluation device used can be a Macsorb HM model-1210 manufactured by Mountech.

[0038] [2nd A process] This step is a step in which the surface of the organosilicon-containing compound-coated nitride filler obtained in step 1A is treated with a basic substance to obtain an organosilicon-containing compound-coated nitride filler having silanol groups on its surface. Specifically, this is a process in which the surface of the organosilicon-containing compound-coated nitride filler obtained in step 1A is reacted with a basic substance to convert -Si-H groups (active hydrogen groups) into -Si-OH groups (silanol groups).

[0039] 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, and examples include aqueous ammonia, monoethylamine, diethylamine, triethylamine, 2-ethanolamine, etc. From the viewpoint of ease of separation, aqueous ammonia is preferred.

[0040] The treatment is carried out by a dipping method or a vapor phase deposition method.

[0041] (Immersion method) The immersion method is a film-forming method in which the organosilicon-containing compound-coated nitride filler obtained in step 1A is immersed in an aqueous solution of a basic substance, etc., and the basic substance acts on the surface of the organosilicon-containing compound-coated nitride filler, converting -Si-H groups (active hydrogen groups) to -Si-OH groups (silanol groups).

[0042] It is preferable that the basic substance in Step 2A is aqueous ammonia, and the treatment is carried out by immersion in the aqueous ammonia.

[0043] 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 residual organosilicon compounds and reducing the risk to the working environment. There are no particular restrictions on the amount of ammonia water, but 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 of at least one-third the particle mass but not more than the same mass as the particle mass. Also, 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 of at least half the particle mass but not more than twice the particle mass. There are no particular limitations as long as the entire particles are immersed in ammonia water. As the particle size becomes smaller, the particle surface tends to be 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 wetting of the particle surface with the ammonia water, so further ethanol can be added while stirring. The reaction can be carried out with constant stirring, but it also works well with intermittent hand-mixing and static conditions. There are no particular restrictions on the container used for hand-mixing, but it is preferable to use a polyethylene wide-mouth bottle with a volume about twice the total volume of the contents. The treatment temperature is preferably between 20°C and 60°C, but since a large amount of hydrogen is generated immediately after treatment, it is preferable to start treatment at 20°C for safety reasons. The treatment time is preferably 20 hours or more and 30 hours or less, and more preferably 22 hours or more and 27 hours or less. After the treatment with the basic substance is complete, the residue is filtered by suction filtration using filter paper. The filter cake is thoroughly washed with distilled water and then washed with ethanol to facilitate drying. Final washing with acetone speeds drying. The filter cake is dried at 90°C for 2 hours to obtain, for example, aluminum nitride particles coated with an organosilicon-containing compound having silanol groups on the surface or silica-coated aluminum nitride particles coated with an organosilicon-containing compound having silanol groups on the surface.

[0044] (vapor phase deposition method) The vapor phase film formation method is a film formation method in which an aqueous solution of a basic substance is vapor-phase formed on the organosilicon-containing compound-coated nitride filler obtained in step 1A, and the basic substance is allowed to act on the surface of the organosilicon-containing compound-coated nitride filler, thereby converting -Si-H groups (active hydrogen groups) to -Si-OH groups (silanol groups).

[0045] It is preferable that the basic substance in the step 2A is aqueous ammonia, and the treatment is carried out by a vapor phase film formation method.

[0046] In the vapor phase film formation method, the concentration of the basic substance is not particularly limited, but for example, when ammonia water is used as the basic substance, it is preferable to open a gas vent hole in the airtight container and place it in a location where local exhaust can be performed.The concentration of ammonia water is preferably 0.01N or more and 10.0N or less, more preferably 0.10N or more and 5.0N or less, and even more preferably 0.50N or more and 1.50N or less, from the viewpoint of suppressing the side reaction of residual organosilicon compounds and reducing the risk of working environment. In the case of the vapor phase film formation method, the reaction rate is slower than in the immersion method using aqueous ammonia, so the treatment temperature is preferably 20°C or higher and 80°C or lower, more preferably 20°C or higher and 70°C or lower, and even more preferably 30°C or higher and 60°C or lower. The treatment time for vapor phase film formation using aqueous ammonia 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 treatment is performed at 50°C, sufficient silanol groups can be introduced in 4 to 5 hours.

[0047] [1st P process] This step involves bringing an organosilicon compound containing the structure represented by general formula (1) and the basic substance into the same atmosphere, treating the organosilicon compound and the basic substance simultaneously, and covering the surface of a nitride filler to obtain an organosilicon-containing compound-coated nitride filler having silanol groups on its surface.

[0048] The treatment uses a vapor-phase simultaneous deposition method.

[0049] (Vapor phase simultaneous deposition method) The vapor-phase simultaneous film-forming method is a method in which the organosilicon compound and the basic substance are allowed to coexist in the same atmosphere, and the organosilicon compound having the structure represented by general formula (1) and the basic substance are treated simultaneously to convert -Si-H groups (active hydrogen groups) of the organosilicon compound on the surface of the nitride filler to -Si-OH groups (silanol groups).

[0050] In the first P step, ammonia water, which is a volatile basic substance, is used to supply moisture essential for the reaction, so it is preferable that the basic substance in the first P step is ammonia water and that the treatment is carried out by a vapor-phase simultaneous film formation method.

[0051] In the simultaneous vapor-phase film-forming method, the concentration of the basic substance is not particularly limited, but for example, when ammonia water is used as the basic substance, it is preferable to open a gas vent hole in the airtight container and place it in a location where local exhaust can be performed.The concentration of ammonia water is preferably 0.01N or more and 10.0N or less, more preferably 0.10N or more and 5.0N or less from the viewpoint of suppressing the side reaction of residual organosilicon compounds and reducing the risk of working environment, and even more preferably 0.50N or more and 1.50N or less. In the case of the vapor-phase simultaneous film-forming method, the processing temperature is preferably 40°C or higher and 65°C or lower, more preferably 45°C or higher and 65°C or lower, and even more preferably 50°C or higher and 65°C or lower, although this depends on the boiling point and vapor pressure of the silicone compound containing the structure represented by formula (1). The treatment time depends on the treatment temperature, but is preferably 3 to 12 hours, more preferably 4 to 10 hours, and even more preferably 5 to 7 hours. If the concentration and temperature are outside these ranges, the reaction time becomes too long or the reaction becomes too vigorous, which is not preferred. After the vapor-phase simultaneous film-forming method is completed, it is preferable to dry the film at 90° C. for 2 hours.

[0052] <Method for producing silica-coated nitride filler particles coated with organosilicon-containing compound having silanol groups> The method for producing silica-coated nitride filler particles coated with an organosilicon-containing compound having silanol groups of the present invention is a method for producing silica-coated nitride filler particles coated with an organosilicon-containing compound having silanol groups, the method comprising: a silica-coated nitride filler; and an organosilicon-containing compound coating film covering the surface of the silica-coated nitride filler and having silanol groups on the surface thereof, The method comprises a step 1B of covering the surface of the silica-coated nitride filler with an organosilicon compound having a structure represented by the following general formula (1) to obtain an organosilicon-containing compound-coated silica-coated nitride filler coated with the organosilicon compound, and a step 2B of treating the surface of the organosilicon-containing compound-coated silica-coated nitride filler with a basic substance to obtain an organosilicon-containing compound-coated silica-coated nitride filler having silanol groups on its surface: Or, The method is characterized by including a 1Q step in which an organosilicon compound having a structure represented by the following general formula (1) and a basic substance are allowed to coexist in the same atmosphere, the organosilicon compound and the basic substance are treated simultaneously to cover the surface of the silica-coated nitride filler, and an organosilicon-containing compound-coated silica-coated nitride filler having silanol groups on the surface is obtained. [ka] (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.)

[0053] [1B process] This step is a step of covering the surface of a silica-coated nitride filler with an organosilicon compound containing the structure represented by the above formula (1) to obtain the silica-coated nitride filler covered with the organosilicon compound.

[0054] (Silica-coated aluminum nitride particles) In the method for producing silica-coated nitride filler particles coated with an organosilicon-containing compound having silanol groups of the present invention, the silica-coated aluminum nitride particles used as a raw material are prepared using the above-mentioned aluminum nitride, for example, using the method described in

[0040] to

[0061] of WO 2020 / 040309.

[0055] (Silica-coated boron nitride particles) In the method for producing silica-coated nitride filler particles coated with an organosilicon-containing compound having silanol groups of the present invention, the silica-coated boron nitride particles used as a raw material are prepared using the above-mentioned boron nitride, for example, using the method described in

[0040] to

[0061] of International Publication No. 2020 / 040309.

[0056] <Organic silicone compounds used for coating> In the method for producing silica-coated nitride filler particles coated with an organosilicon-containing compound having silanol groups according to the present invention, the organosilicon compound used as the raw material for the organosilicon-containing compound coating that constitutes the organosilicon-containing compound-coated silica-coated nitride filler particles is an organosilicon compound having a structure represented by the above formula (1). It can be used without particular restrictions, regardless of whether it is linear, cyclic, or branched. The structure represented by formula (1) is a hydrogensiloxane unit in which hydrogen is directly bonded to a silicon atom.

[0057] In the above formula (1), as the alkyl group R having 1 to 4 carbon atoms, from the viewpoint of volatilizing the silicone compound, a methyl group, an ethyl group, a propyl group, a t-butyl group, etc. are preferred, and a methyl group is particularly preferred. In the method of producing organosilicon-containing compound-coated silica-coated nitride filler particles having silanol groups of the present invention, the organosilicon compound used as a raw material is, for example, an oligomer or polymer containing a structure represented by formula (1).

[0058] 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. [ka] (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.)

[0059] [ka] (In formula (3), n is an integer of 3 to 6.)

[0060] In particular, a cyclic hydrogensiloxane oligomer in which n is 4 in the above formula (3) is excellent in that it can form a uniform coating on the surface of aluminum nitride particles. The weight-average molecular weight of the organosilicone compound containing the structure shown in formula (1) is preferably 100 to 2000, more preferably 150 to 1000, and even more preferably 180 to 500. It is presumed that by using an organosilicone compound containing the structure shown in formula (1) with a weight-average molecular weight within this range, it is easy to form a thin and uniform coating on the surface of silica-coated nitride filler particles. In addition, it is preferable that m in formula (2) is 1.

[0061] In step 1B, the surface of the silica-coated nitride filler is covered with an organosilicone compound containing the structure represented by formula (1) above. In Step 1B, the surface of the silica-coated nitride filler can be coated with an organosilicon compound having the structure represented by Formula (1). Examples of methods for Step 1B include a dry mixing method in which an organosilicon compound is added by spraying or the like while stirring the raw silica-coated nitride filler using a general powder mixer, followed by dry mixing to coat the filler. Examples of powder mixers 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 magnetically coupled stirrer in a sealed container. The temperature conditions in this case depend on the boiling point and vapor pressure of the silicone compound having the structure represented by Formula (1), and are not particularly limited. A preferred temperature is 10°C to 200°C, more preferably 20°C to 150°C, and even more preferably 40°C to 100°C.

[0062] Alternatively, step 1B can be performed using a gas-phase adsorption method in which vapor of an organosilicon compound containing the structure represented by formula (1), either alone or in a mixture with an inert gas such as nitrogen gas, is deposited or evaporated onto the surface of a stationary silica-coated nitride filler. The temperature conditions in this case vary depending on the boiling point and vapor pressure of the silicone compound containing the structure represented by formula (1), but are preferably 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. The system can be pressurized or depressurized as needed (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 can easily replace the gas within the system, such as a glass container, a desiccator, or a CVD apparatus. If the silica-coated nitride filler 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.

[0063] The amount of the organosilicon compound containing the structure represented by formula (1) used in step 1B is not particularly limited. In the silica-coated nitride filler coated with the organosilicon compound containing the structure represented by formula (1) obtained in step 1B, the coating amount of the organosilicon compound containing the structure represented by formula (1) is determined by the BET method. 2 / g) to calculate the surface area of ​​1m 2 The coating weight 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. If the coating weight is too high, the thermal conductivity will decrease, and conversely, if it is too low, the moisture resistance will be insufficient. The specific surface area (m 2 / g) to calculate the surface area of ​​1m 2 The coating amount of the organosilicon compound containing the structure represented by formula (1) per silica-coated nitride filler was calculated by multiplying the mass difference between the silica-coated nitride filler before and after coating with the organosilicon compound by the specific surface area (m ) of the silica-coated nitride filler determined by the BET method. 2 Surface area (m2) calculated from 2 ) can be found by dividing by The specific surface area determined by the BET method can be measured by a nitrogen adsorption BET single-point method using a gas flow method. The evaluation device used can be a Macsorb HM model-1210 manufactured by Mountech.

[0064] [2nd B process] In this step, the surface of the organosilicon-containing compound-coated silica-coated nitride filler obtained in step 1B is treated with a basic substance to obtain an organosilicon-containing compound-coated silica-coated nitride filler having silanol groups on its surface. Specifically, this is a process in which the surface of the organosilicon-containing compound-coated silica-coated nitride filler obtained in step 1B is reacted with a basic substance to convert -Si-H groups (active hydrogen groups) into -Si-OH groups (silanol groups). As the basic substance, the same substances as those in Step 2A can be used, and the preferred basic substances etc. are also the same.

[0065] The treatment is carried out by using a dipping method or a vapor phase film formation method, similarly to the step 2A.

[0066] (Immersion method) The immersion method is a film-forming method in which the organosilicon-containing compound-coated silica-coated nitride filler obtained in step 1B is immersed in an aqueous solution of a basic substance, etc., to allow the basic substance to act on the surface of the organosilicon-containing compound-coated silica-coated nitride filler, converting -Si-H groups (active hydrogen groups) to -Si-OH groups (silanol groups), as shown in the following formula (Z): [ka]

[0067] It is preferable that the basic substance in Step 2B is aqueous ammonia, and the treatment is carried out by immersion in the aqueous ammonia.

[0068] In the immersion method, the concentration of the basic substance is not particularly limited. For example, when ammonia water is used as the basic substance, the concentration is preferably 0.01 N or more and 10.0 N or less from the viewpoint of reaction rate, 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. Regarding the amount of ammonia water, for example, when the particle diameter (D50) of the silica-coated 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 of at least one-third the particle mass but not more than the same mass as the particle mass. Also, 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 of at least half the particle mass but not more than twice the particle mass. There are no particular restrictions as long as approximately one-third of the particle surface area is immersed in the ammonia water. As the particle size decreases, the particle surface tends to become less wettable with the 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 the ammonia water, so further ethanol can be added while stirring. The reaction can be carried out with constant stirring, but is also sufficient under stationary conditions with intermittent hand mixing. There are no particular restrictions on the container for hand mixing, but it is preferable to use a polyethylene wide-mouth bottle with a volume approximately twice the total volume of the contents. The treatment temperature is preferably between 20°C and 60°C, but since a large amount of hydrogen is generated immediately after treatment, it is preferable to start treatment at 20°C for safety reasons. The treatment time is preferably 20 hours or more and 30 hours or less, and more preferably 22 hours or more and 27 hours or less. After the basic substance treatment is complete, the residue is filtered by suction filtration using filter paper. The filter cake is thoroughly washed with distilled water, then washed with ethanol to facilitate drying. A final wash with acetone speeds up drying. The filter cake is dried at 90°C for 2 hours to obtain, for example, silica-coated aluminum nitride particles coated with an organosilicon-containing compound having silanol groups on the surface.

[0069] (vapor phase deposition method) The vapor phase film formation method is a film formation method in which an aqueous solution of a basic substance is vapor-phase formed on the silica-coated nitride filler coated with an organosilicon-containing compound obtained in step 1B, and the basic substance acts on the surface of the silica-coated nitride filler coated with the organosilicon-containing compound, thereby converting -Si-H groups (active hydrogen groups) into -Si-OH groups (silanol groups), as shown in formula (Z).

[0070] It is preferable that the basic substance in the step 2B is aqueous ammonia, and the treatment is carried out by a vapor phase film formation method.

[0071] In the vapor phase film formation method, the concentration of the basic substance is not particularly limited, but for example, when ammonia water is used as the basic substance, it is preferable to carry out the process in an airtight container with a gas vent hole opened and in a location where local exhaust is possible. The concentration of ammonia water is preferably 0.01N or more and 10.N or less, more preferably 0.1N or more and 5N or less, and even more preferably 0.5N or more and 1.5N or less, from the viewpoint of suppressing side reactions of residual organosilicon compounds and reducing working environment risks. In the case of the vapor phase film formation method, the reaction rate is slower than in the immersion method using aqueous ammonia, so the treatment temperature is preferably 20°C or higher and 80°C or lower, more preferably 20°C or higher and 70°C or lower, and even more preferably 30°C or higher and 60°C or lower. The treatment time for the vapor phase film formation method using aqueous ammonia is about 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 treatment is performed at 50°C, sufficient silanol groups can be introduced in about 4 to 5 hours. After the base treatment is completed, it is preferable to dry the material at 90°C for 2 hours.

[0072] [1st Q process] This process involves bringing an organosilicon compound containing the structure represented by general formula (1) and the basic substance into the same atmosphere, treating the organosilicon compound and the basic substance simultaneously to coat the surface of the silica-coated nitride filler, thereby obtaining an organosilicon-containing compound-coated silica-coated nitride filler having silanol groups on its surface.

[0073] The treatment uses a vapor-phase simultaneous deposition method.

[0074] (Vapor phase simultaneous deposition method) The vapor-phase simultaneous film-forming method is a method in which the organosilicon compound and the basic substance are allowed to coexist in the same atmosphere, the organosilicon compound having the structure represented by general formula (1) and the basic substance are treated simultaneously, and the -Si-H groups (active hydrogen groups) of the organosilicon compound are converted to -Si-OH groups (silanol groups) on the surface of the silica-coated nitride filler to form a film.

[0075] In the first Q step, ammonia water, which is a volatile basic substance, is used to supply moisture essential for the reaction, so that it is preferable that the basic substance in the first Q step is ammonia water and that the treatment is carried out by a vapor-phase simultaneous film-forming method.

[0076] In the simultaneous vapor-phase film-forming method, the concentration of the basic substance is not particularly limited, but for example, when ammonia water is used as the basic substance, it is preferable to open a gas vent hole in the airtight container and place it in a location where local exhaust can be performed.The concentration of ammonia water is preferably 0.01N or more and 10.0N or less, more preferably 0.10N or more and 5.0N or less from the viewpoint of suppressing the side reaction of residual organosilicon compounds and reducing the risk of working environment, and even more preferably 0.50N or more and 1.50N or less. In the case of the vapor-phase simultaneous film-forming method, the processing temperature is preferably 40°C or higher and 65°C or lower, more preferably 45°C or higher and 65°C or lower, and even more preferably 50°C or higher and 65°C or lower, although this depends on the boiling point and vapor pressure of the silicone compound containing the structure represented by formula (1). The treatment time depends on the treatment temperature, but is preferably 3 hours or more and 12 hours or less, more preferably 4 hours or more and 10 hours or less, and even more preferably 5 hours or more and 7 hours or less. After the vapor-phase simultaneous film-forming method is completed, it is preferable to dry the film at 90° C. for 2 hours.

[0077] (Surface treatment agent) It is preferred that the surface treatment agent adheres to the surface of the nitride filler coated with an organosilicon-containing compound having a silanol group or the silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group obtained in the present invention through reaction or interaction.

[0078] The surface treatment agent may be a silane coupling agent, a compound having one or more groups selected from the group consisting of an amino group, a carboxyl group, and an epoxy group, or a modified silicone oil. Of these, a silane coupling agent is preferably used.

[0079] The silane coupling agent may be any known compound as long as it has a hydrolyzable substituent such as a halogen atom or an alkoxy group on the silicon atom. For example, vinyltrichlorosilane, vinyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane (manufactured by Shin-Etsu Silicones Co., Ltd., KBM-3103), n-dodecyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, hexamethyldisilazane (manufactured by Shin-Etsu Silicones Co., Ltd., SZ-31), etc. are preferably used. These silane coupling agents may be used alone or in combination.

[0080] As the compound having one or more groups selected from the group consisting of an amino group, a carboxyl group, and an epoxy group, a compound that is easily adsorbed to or reacts with the surface of each nitride filler due to the action of these groups is preferred, and known compounds can be used. For example, 1,2-epoxyhexane, 1,2-epoxydodecane, n-hexylamine, n-dodecylamine, pn-hexylaniline, n-hexylcarboxylic acid, n-dodecylcarboxylic acid, pn-hexylbenzoic acid, and the like are preferred.

[0081] Modified silicone oils include KF-105, KF-101, KF-102, X-22-173DX, KF-393, KF-864, KF-8012, KF-857, X-22-3667, X-22-162A, and X-22-3701E (all manufactured by Shin-Etsu Chemical Co., Ltd.), TSF4700, TSF4701, TSF4702, TSF4703, TSF4730*, TSF4770, and TSE30. 70 (all manufactured by Momentive), SF8417, BY16-828, BY16-849, BY16-892, BY16-853, BY16-837, SF8411, BY16-875, BY16-855, SF8421, SF8418, BY16-874 (all manufactured by DuPont Toray Specialty Materials), and the like are preferred, and these can be used alone or in combination.

[0082] There are no particular limitations on the method for coating the nitride filler coated with an organosilicon-containing compound having a silanol group or the silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group with these compounds, and any known method can be used. For example, there is the direct method, in which the filler is surface treated beforehand. Direct methods include the dry method, impregnation method, and integral method. The dry method involves dripping a chemical onto the filler and stirring and mixing, and in some cases evaporating and drying the solvent that diluted the chemical and reaction by-products. The impregnation method involves immersing the filler in a solution of the surface treatment agent, stirring and mixing, filtering, and then evaporating and drying the solvent and reaction by-products. The integral method involves adding the surface treatment agent when kneading with the polymer. The processing equipment includes a Henschel mixer, a Nauta mixer, etc., the mixing equipment includes a kneader, a planetary mixer, etc., and the drying may be performed by oven drying, natural drying, or other known methods.

[0083] The amount of silane coupling agent coated on the nitride filler coated with an organosilicon-containing compound having a silanol group or the silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group is preferably 0.05% to 10.0% by mass relative to the nitride filler or silica-coated nitride filler. By setting the amount to 0.05% by mass or more, the coating effect is easily achieved. By setting the amount to 10.0% by mass or less, the content of unreacted silane coupling agent, etc. is reduced, and less of it remains as impurities. The charging ratio of the silane coupling agent is preferably 0.5 to 180 times, more preferably 1.0 to 120 times, and even more preferably 2.0 to 100 times, from the viewpoint of reducing the viscosity of the slurry flow and preventing the filler from agglomerating due to unreacted silane coupling agent. The charging ratio of the silane coupling agent indicates the charging ratio when the charging amount calculated from the BET specific surface area of ​​the nitride filler and the minimum coating area of ​​the silane coupling agent is set to 1. The minimum coating area of ​​the silane coupling agent was calculated using the following formula based on the molecular weight of the silane coupling agent. Minimum coverage area [m 2 / g] = 6.02 × 10 23 x13x10 -20 / Molecular weight of silane coupling agent

[0084] [Method for producing resin composition] A resin composition can be produced by using a nitride filler coated with an organosilicon-containing compound having silanol groups, which has been surface-treated on the nitride filler coated with an organosilicon-containing compound having silanol groups obtained by the production method of the present invention, or a silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups, which has been surface-treated on the silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups. That is, the method for producing a resin composition in the present invention may include a production step of producing a nitride filler coated with an organosilicon-containing compound having silanol groups by the above-mentioned method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups or a method for producing a surface-treated nitride filler coated with an organosilicon-containing compound having silanol groups, a production step of producing a nitride filler coated with an organosilicon-containing compound having surface-treated silanol groups, and a mixing step of mixing the surface-treated nitride filler coated with an organosilicon-containing compound having silanol groups with a resin. Alternatively, the method for producing a resin composition in the present invention may include a production step of producing a silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups by the above-mentioned method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups, or a method for producing a surface-treated silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups, a production step of producing a silica-coated nitride filler coated with an organosilicon-containing compound having surface-treated silanol groups, and a mixing step of mixing the surface-treated silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups with a resin.

[0085] In the mixing step, the surface-treated organosilicon-containing compound-coated nitride filler having silanol groups, which is produced by the method for producing the surface-treated organosilicon-containing compound-coated nitride filler having silanol groups, is mixed with a resin. Alternatively, in the mixing step, a silica-coated nitride filler coated with an organosilicon-containing compound having a surface-treated silanol group, which is produced by the method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a surface-treated silanol group, is mixed with a resin. The resin to be mixed in the mixing step is not particularly limited, but from the viewpoint of heat resistance, examples include thermosetting resins, thermoplastic resins, or mixtures of thermosetting resins and thermoplastic resins. A thermosetting resin having a functional group (e.g., a vinyl group, an allyl group, etc.) capable of reacting with an active hydrogen group, or having such a group introduced therein, is preferred from the viewpoint of controlling the viscosity of the slurry. Examples of such thermosetting resins include silicone resins such as polydimethylsiloxane, epoxy resins, phenolic resins, bismaleimide resins, cyanate resins, urethane resins, (meth)acrylic resins, vinyl ester resins, unsaturated polyester resins, and polyvinyl alcohol acetal resins. These resins can be used alone or in combination of two or more. Furthermore, a mixture of a thermosetting resin with the above-mentioned curing agent and curing accelerator may also be used. Epoxy resins are particularly preferred due to their excellent heat resistance, adhesiveness, and electrical properties after curing, while silicone resins are preferred for applications where flexibility and adhesion are important.

[0086] 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 with two or more 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, platinum metal-based curing catalysts can be used, and the amount added can be adjusted to achieve the desired hardness of the cured resin.

[0087] Examples of epoxy resins include bifunctional glycidyl ether type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, and biphenyl type epoxy resin; 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.

[0088] When the above-mentioned epoxy resin is used, a curing agent and a curing accelerator may be blended therein. Examples of curing agents 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; phenolic 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 curing catalysts 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.

[0089] In the mixing step, in addition to the above-mentioned nitride filler coated with an organosilicon-containing compound having a silanol group or the above-mentioned silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group, a commonly used filler such as alumina, silica, zinc oxide, etc. may also be used in combination.

[0090] In the mixing step, the filler other than the surface-treated organosilicon-containing compound-coated nitride filler having a silanol group and the surface-treated organosilicon-containing compound-coated nitride filler having a silanol group, or the surface-treated organosilicon-containing compound-coated silica-coated nitride filler having a silanol group and the surface-treated organosilicon-containing compound-coated silica-coated nitride filler having a silanol group, may be mixed in an amount sufficient to produce a desired resin composition. The total volume content of fillers other than the surface-treated silanol-containing organosilicon-containing compound-coated nitride filler and the surface-treated silanol-containing organosilicon-containing compound-coated nitride filler in the obtained resin composition, or the total volume content of fillers other than the surface-treated silanol-containing organosilicon-containing compound-coated silica-coated nitride filler and the surface-treated silanol-containing organosilicon-containing compound-coated silica-coated nitride filler, is preferably 50% by volume or more and 99% by volume or less, more preferably 60% by volume or more and 97% by volume or less, and even more preferably 70% by volume or more and 95% by volume or less. If the total volume content is 50% by volume or more, it can exhibit good heat dissipation properties, and if it is 99% by volume or less, it can obtain good workability when using the resin composition.

[0091] The volume content of the surface-treated silanol-containing organosilicon-containing compound-coated nitride filler in the resulting resin composition is preferably 30% to 100% by volume, more preferably 40% to 100% by volume, and even more preferably 50% to 100% by volume of the total volume content of the surface-treated silanol-containing organosilicon-containing compound-coated nitride filler and fillers other than the surface-treated silanol-containing organosilicon-containing compound-coated nitride filler. A total volume content of 30% or more can exhibit good heat dissipation properties. In addition, the content by volume of the surface-treated silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group in the resulting resin composition is preferably 30% by volume or more and 100% by volume or less of the total content by volume of the silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group and the fillers other than the surface-treated silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group, more preferably 40% by volume or more and 100% by volume or less, and even more preferably 50% by volume or more and 100% by volume or less. A total content by volume of 30% by volume or more can exhibit good heat dissipation properties.

[0092] In the mixing step, flexibility-imparting agents such as silicone, urethane acrylate, butyral resin, acrylic rubber, diene rubber and copolymers thereof, silane coupling agents, titanium coupling agents, inorganic ion scavenger agents, pigments, dyes, diluents, solvents, etc. may also be added as needed.

[0093] The mixing method in the mixing step is not particularly limited, and examples include a method in which a surface-treated organosilicon-containing compound-coated nitride filler having silanol groups, or a surface-treated organosilicon-containing compound-coated silica-coated nitride filler having silanol groups, a resin, other additives, etc. are mixed together or divided into portions, and mixed, dissolved, and kneaded using a dispersing / dissolving device such as a grinder, planetary mixer, rotation-revolution mixer, kneader, or roll mill, either alone or in appropriate combinations, with heating as necessary, to obtain a slurry, etc.

[0094] The resin composition thus obtained can be formed into a sheet and, if necessary, reacted to form a heat-dissipating sheet. The resin composition and heat-dissipating sheet described above can be suitably used for adhesive applications such as semiconductor power devices and power modules.

[0095] <Nitride filler coated with organosilicon-containing compound having silanol groups> The nitride filler coated with an organosilicon-containing compound having silanol groups of the present invention comprises a nitride filler and an organosilicon-containing compound that covers the surface of the nitride filler and has a density of 0.5 to 2.1 / nm 2 and an organosilicon-containing compound coating having silanol groups present at an average surface density of 1000 nm to 1000 nm.

[0096] (average surface density of silanol groups) The average surface density of the silanol groups on the nitride filler coated with the organosilicon-containing compound having silanol groups is 0.5 to 2.1 / nm 2 0.5 particles / nm 2If the density is less than this, a sufficient slurry viscosity reduction effect cannot be obtained. The maximum number of silanol groups that can be introduced is largely determined by the type of organosilicon material used in CVD, but even if the treatment temperature is set to 50°C or higher or the treatment time is extended in order to increase the reaction rate, the density will not exceed 2.1 / nm. 2 It will never exceed. The average surface density of silanol groups is preferably 0.6 to 2.1 / nm from the viewpoint of obtaining a sufficient slurry viscosity reducing effect. 2 and more preferably 0.7 to 2.1 particles / nm 2 is. The average surface density of silanol groups can be reduced by subjecting the organosilicon material to heat treatment at a temperature between 150°C and 250°C for two hours after CVD treatment and before treatment with ammonia water. The temperature and time can be freely set based on the cumulative amount of heat exposure, but as a guideline, an average surface density of silanol groups of 1.3 / nm is achieved after two hours at 150°C. 2 It can be reduced to about two-thirds by heating at 200°C for two hours, and to about one-quarter by heating at 200°C for two hours. In the present invention, the average surface density of silanol groups on the nitride filler coated with an organosilicon-containing compound having silanol groups can be measured, for example, by the method described in the examples below.

[0097] It is preferable that the surface of the nitride filler coated with an organosilicon-containing compound having a silanol group is further provided with a surface treatment agent.

[0098] The surface treatment agent may be a silane coupling agent, a compound having one or more groups selected from the group consisting of an amino group, a carboxyl group, and an epoxy group, or a modified silicone oil. Among these, the surface treatment agent is preferably a silane coupling agent in view of reactivity with the silanol groups on the surface of the nitride filler coated with an organosilicon-containing compound having silanol groups.

[0099] The amount of silane coupling agent or the like coated on the nitride filler coated with an organosilicon-containing compound having a silanol group is preferably 0.05% by mass to 5.0% by mass relative to the nitride filler coated with an organosilicon-containing compound having a silanol group. By setting the amount to 0.05% by mass or more, the coating effect is easily obtained. By setting the amount to 5.0% by mass or less, the content of unreacted silane coupling agent or the like is reduced, and less of it remains as an impurity.

[0100] <Silica-coated nitride filler coated with organosilicon-containing compound having silanol groups> The silica-coated nitride filler of the present invention is a silica-coated nitride filler and a silica-coated nitride filler having an organosilicon-containing compound coated with silanol groups, the silica-coated nitride filler and a silica-coated nitride filler having an organosilicon-containing compound coated with silanol groups and ... 2 and an organosilicon-containing compound coating having silanol groups present at an average surface density of 1000 nm to 1000 nm.

[0101] (average surface density of silanol groups) The average surface density of the silanol groups on the organosilicon-containing compound-coated silica-coated nitride filler having silanol groups is 0.5 to 2.1 / nm 2 0.5 particles / nm 2 If the density is less than this, a sufficient slurry viscosity reduction effect cannot be obtained. The maximum number of silanol groups that can be introduced is largely determined by the type of organosilicon material used in CVD, but even if the treatment temperature is set to 50°C or higher or the treatment time is extended in order to increase the reaction rate, the density will not exceed 2.1 / nm. 2 It will never exceed. The average surface density of silanol groups is preferably 0.6 to 2.1 / nm from the viewpoint of obtaining a sufficient slurry viscosity reducing effect. 2 and more preferably 0.7 to 2.1 particles / nm 2 is. The average surface density of silanol groups can be reduced by subjecting the organosilicon material to heat treatment at a temperature between 150°C and 250°C for two hours after CVD treatment and before treatment with ammonia water. The temperature and time can be freely set based on the cumulative amount of heat exposure, but as a guideline, an average surface density of silanol groups of 1.3 / nm is achieved after two hours at 150°C. 2 It can be reduced to about two-thirds by heating at 200°C for two hours, and to about one-quarter by heating at 200°C for two hours. In the present invention, the average surface density of silanol groups on the organosilicon-containing compound-coated silica-coated nitride filler having silanol groups can be measured, for example, by the method described in the examples below.

[0102] It is preferable that the surface of the silanol group-containing organosilicon-containing compound-coated silica-coated nitride filler further be provided with a surface treatment agent.

[0103] The surface treatment agent may be a silane coupling agent, a compound having one or more groups selected from the group consisting of an amino group, a carboxyl group, and an epoxy group, or a modified silicone oil. Among these, the surface treatment agent is preferably a silane coupling agent in view of reactivity with the silanol groups on the surface of the silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups.

[0104] The amount of silane coupling agent or the like coated on the silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group is preferably 0.05% by mass to 5.0% by mass relative to the silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group. By setting the amount to 0.05% by mass or more, the coating effect is easily obtained. By setting the amount to 5.0% by mass or less, the content of unreacted silane coupling agent or the like is reduced, and less of it remains as an impurity. [Example]

[0105] 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.

[0106] [Preparation of silica-coated aluminum nitride particles] The surface coating of aluminum nitride particles A was carried out using a vacuum desiccator made of acrylic resin with a thickness of 20 mm, internal dimensions of 260 mm x 260 mm x 100 mm, and a structure divided into two levels, upper and lower, by a partition with through holes. First, place a sample with a cumulative volume 50% particle size (D50) of 80 μm and a specific surface area (BET method) of 0.08 m on the top shelf of a vacuum desiccator. 2 200 g of aluminum nitride particles A (FAN-f80-A1, manufactured by Furukawa Denshi Co., Ltd.) with a mass of 1 / g was uniformly spread on a stainless steel tray and allowed to stand. Next, 20 g of organosilicon compound A (2,4,6,8-tetramethylcyclotetrasiloxane (D4H): manufactured by Tokyo Chemical Industry Co., Ltd.), where n = 4 in formula (3), was placed in a φ120 glass Petri dish in the lower part of the vacuum desiccator and allowed to stand. The vacuum desiccator was then sealed, and a CVD treatment was carried out in an oven at 80°C for 8 hours. The sample was then transferred to an alumina crucible and heat-treated at 850°C for 6 hours to obtain silica-coated aluminum nitride particles A. In the above, aluminum nitride particles A are used, each having a cumulative volume 50% particle size (D50) of 1.0 μm and a specific surface area by the BET method of 2.4 m 2 Silica-coated aluminum nitride particles B were obtained in the same manner as above, except that the aluminum nitride particles B (TFZ-N01P: manufactured by Toyo Aluminum Co., Ltd.) were used and the heat treatment at 850°C for 6 hours was changed to the heat treatment at 700°C for 3 hours.

[0107] Example 1 [Preparation of silanol-group-introduced silica-coated aluminum nitride particles (dipping method) and surface treatment] 11.0 g of 2,4,6,8-tetramethylcyclotetrasiloxane (D4H) was placed in a φ50 glass Petri dish at the bottom of an 8 L SUS pressure vessel. Next, 200 g of the silica-coated aluminum nitride particles A were placed in an aluminum foil tray, which was then 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 subjected to CVD treatment for 4.5 hours in a sealed oven maintained at 80°C (D4H concentration: D4H partial pressure 1.30 × 10 4 Pa (80°C) [CVD1 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 bottle was manually stirred every hour for the first three hours, and then left to stand in a local exhaust system at room temperature for 24 hours. The bottle was left unsealed during the standing period, allowing the evolved hydrogen to leak through the gap in the lid. After 24 hours, the bottle was vacuum filtered using filter paper with a coarseness sufficient to maintain the particle size. The filter cake was washed twice with distilled water and twice with ethanol, and then dried at 90°C for two hours to obtain silica-coated aluminum nitride particles A with silanol groups introduced (immersion method). Next, 100 parts by mass of silica-coated aluminum nitride particles A having silanol groups introduced therein were mixed with 2.4 parts by mass of a silane coupling agent (KBM-3103: decyltrimethoxysilane, manufactured by Shin-Etsu Silicones Co., Ltd.) by impregnation, and the silica-coated aluminum nitride particles A having silanol groups introduced therein were subjected to a surface treatment (SC1 treatment). The silane coupling agent was added at a ratio of 90. The mixture was then left to dry at room temperature for 2 hours, and then heat-treated in a dryer at 120°C for 2 hours, thereby obtaining a sample of silica-coated aluminum nitride particles A having silanol groups introduced therein and surface-treated with the silane coupling agent. The charging ratio of the silane coupling agent indicates the charging ratio when the charging amount calculated from the BET specific surface area of ​​aluminum nitride particles A and the minimum coating area of ​​the silane coupling agent is taken as 1. The minimum coating area of ​​the silane coupling agent was calculated using the following formula based on the molecular weight of the silane coupling agent. Minimum coverage area [m2 / g] = 6.02 × 10 23 x13x10 -20 / Molecular weight of silane coupling agent Table 3 shows the CVD treatment conditions, Table 4 shows the basic substance treatment conditions, and Table 5 shows the silane coupling agent treatment conditions in Example 1, Examples 2 to 11 described below, and Comparative Examples 1 to 11 described below.

[0108] Example 2 In Example 1, the CVD treatment conditions were 80°C, 1 hour, and the D4H concentration was 8.12 x 10 2 A sample of silica-coated aluminum nitride particles A was obtained by surface-treating silica-coated aluminum nitride particles A having silanol groups introduced therein with a silane coupling agent in the same manner as in Example 1, except that the temperature was changed to Pa (80°C) [CVD2 treatment].

[0109] Example 3 In Example 1, the CVD treatment conditions were 80°C, 1 hour, and the D4H concentration was 2.03 x 10 2 A sample of silica-coated aluminum nitride particles A was obtained by surface-treating silica-coated aluminum nitride particles A having silanol groups introduced therein with a silane coupling agent in the same manner as in Example 1, except that the temperature was changed to Pa (80°C) [CVD3 treatment].

[0110] Example 4 In Example 1, 100 ml of 1N aqueous ammonia and 100 ml of ethanol were placed in a 1 L polyethylene wide-mouth bottle, and the entire amount of the CVD-treated sample was added thereto. The mixture was manually stirred every hour for the first 3 hours, and then allowed to stand at room temperature for 24 hours in a local exhaust ventilation facility. In the same manner as in Example 1, a sample of silica-coated aluminum nitride particles A in which silanol groups had been introduced and surface-treated with a silane coupling agent was obtained.

[0111] Example 5 [Preparation of Silica-Coated Aluminum Nitride Particles with Silanol Groups (Vapor-Phase Deposition Method) and Surface Treatment] 11.0 g of 2,4,6,8-tetramethylcyclotetrasiloxane (D4H) was placed in a φ50 glass Petri dish at the bottom (lowest level) of an 8 L SUS pressure-resistant container. Next, 200 g of the silica-coated aluminum nitride particles A were placed in an aluminum foil tray, which was then placed on a SUS raised-bottom rack at the top of the 8 L SUS pressure-resistant container. The 8 L pressure-resistant container was then covered with a lid and placed in an oven maintained at 80°C in a sealed state for 10 minutes. After depressurization, the container was again subjected to CVD treatment for 4 hours in an oven maintained at 80°C in a sealed state. (D4H concentration: D4H partial pressure 1.30 x 10 4 Pa (80°C) [CVD4 treatment]. Next, the φ50 glass Petri dish containing the D4H-treated silica-coated aluminum nitride particles A that had been set at the bottom (lowest level) of the 8 L pressure-resistant vessel was removed, and instead, 20 g of 1 N ammonia water was placed in a φ120 glass Petri dish and set at the bottom (lowest level) of the 8 L pressure-resistant vessel. The φ50 glass Petri dish containing the D4H-treated silica-coated aluminum nitride particles A was then set back on top. The Petri dish was left to stand at room temperature for 24 hours with the lid on and one pressure relief hole open, and the sample was removed and dried at 90°C for 2 hours to obtain silica-coated aluminum nitride particles A into which silanol groups had been introduced (vapor-phase deposition method). Next, 100 parts by mass of silica-coated aluminum nitride particles A having silanol groups introduced therein were mixed with 2.4 parts by mass of a silane coupling agent (KBM-3103: decyltrimethoxysilane, manufactured by Shin-Etsu Silicones Co., Ltd.) by impregnation, and surface treatment was carried out (SC1 treatment). The silane coupling agent was added at a ratio of 90. After that, the mixture was left to stand at room temperature for 2 hours to dry, and then heat-treated in a dryer at 120°C for 2 hours to obtain a sample of silica-coated aluminum nitride particles A having silanol groups introduced therein, surface-treated with a silane coupling agent.

[0112] Example 6 In Example 1, a sample of silica-coated aluminum nitride particles A was obtained by surface-treating silica-coated aluminum nitride particles A having silanol groups introduced thereinto with a silane coupling agent in the same manner as in Example 1, except that the CVD treatment conditions were 80°C for 4 hours [CVD4 treatment], the silane coupling agent treatment conditions were a silane coupling agent (SZ-31: hexamethyldisilazane, manufactured by Shin-Etsu Silicones Co., Ltd.) (SC2 treatment), and the silane coupling agent loading ratio was 5.

[0113] Example 7 [Preparation of silanol-containing silica-coated aluminum nitride particles (vapor-phase simultaneous deposition method) and surface treatment] A φ50 glass Petri dish containing 3.0 g of 2,4,6,8-tetramethylcyclotetrasiloxane (D4H) and a φ120 glass Petri dish containing 20 g of 1N aqueous ammonia were placed at the bottom of an 8 L stainless steel pressure vessel. 200 g of the silica-coated aluminum nitride particles A were placed in a φ150 glass Petri dish and placed on a SUS raised-bottom rack at the top of an 8 L SUS pressure vessel. The 8 L pressure vessel was then covered with a lid and allowed to stand in a sealed oven maintained at 60°C for 10 minutes. After depressurization, the vessel was again subjected to CVD treatment for 4 hours in a sealed oven maintained at 60°C (D4H concentration: D4H partial pressure 7.66 × 10 2 Pa (60°C) [CVD5 processing] (vapor phase simultaneous film formation method). Next, 100 parts by mass of silica-coated aluminum nitride particles A having silanol groups introduced therein were mixed with 2.4 parts by mass of a silane coupling agent (KBM-3103: decyltrimethoxysilane, manufactured by Shin-Etsu Silicones Co., Ltd.) by impregnation, and surface treatment was carried out (SC1 treatment). The silane coupling agent was added at a ratio of 90. After that, the mixture was left to stand at room temperature for 2 hours to dry, and then heat-treated in a dryer at 120°C for 2 hours to obtain a sample of silica-coated aluminum nitride particles A having silanol groups introduced therein, surface-treated with a silane coupling agent.

[0114] Example 8 In Example 5, a sample of silica-coated aluminum nitride particles A was obtained by surface-treating silica-coated aluminum nitride particles A having silanol groups introduced therein with a silane coupling agent in the same manner as in Example 5, except that the ammonia treatment temperature was 50°C and the treatment time was 4 hours.

[0115] Example 9 In Example 5, the same procedure as in Example 5 was repeated except that silica-coated aluminum nitride particles A were replaced with silica-coated aluminum nitride particles B, the ammonia treatment temperature was changed to 50°C, the treatment time was changed to 4 hours, and the silane coupling agent loading ratio was changed to 2, thereby obtaining a sample of silica-coated aluminum nitride particles B in which silanol groups had been introduced and surface-treated with a silane coupling agent.

[0116] Example 10 In Example 5, silica-coated aluminum nitride particles A were prepared using a 50% cumulative volume particle size (D50) of 8.5 μm and a specific surface area (BET method) of 4 m 2 The same procedure as in Example 5 was carried out except that the ammonia treatment temperature was 50°C, the treatment time was 4 hours, and the loading ratio of the silane coupling agent was 2, to obtain a sample of boron nitride particles A in which silanol groups had been introduced and the surface of the silane coupling agent had been treated.

[0117] Example 11 In Example 5, silica-coated aluminum nitride particles A were prepared using a particle size (D50) of 1.0 μm at 50% cumulative volume and a specific surface area (BET method) of 9 m. 2 The same procedure as in Example 5 was carried out except that the ammonia treatment temperature was 50°C, the treatment time was 4 hours, and the loading ratio of the silane coupling agent was 2, to obtain a sample of boron nitride particles B in which silanol groups had been introduced and the surface of the silane coupling agent had been treated.

[0118] Example 12 A sample of silica-coated aluminum nitride particles A having silanol groups introduced therein was obtained in the same manner as in Example 8, except that the silane coupling agent treatment was not carried out.

[0119] (Comparative Example 1) The same procedure as in Example 1 was carried out except that the CVD treatment and ammonia treatment were not carried out, to obtain a sample of silica-coated aluminum nitride particles A in which the silica-coated aluminum nitride particles A were surface-treated with a silane coupling agent.

[0120] (Comparative Example 2) The same procedure as in Example 1 was carried out except that the ammonia treatment was not carried out, to obtain a sample of silica-coated aluminum nitride particles A in which the silica-coated aluminum nitride particles A were surface-treated with a silane coupling agent.

[0121] (Comparative Example 3) In Example 1, the silica-coated aluminum nitride particles A were changed to aluminum nitride particles A, and the same procedure as in Example 1 was repeated except that the CVD treatment and ammonia treatment were not performed, thereby obtaining a sample of aluminum nitride particles A in which the aluminum nitride particles A were surface-treated with a silane coupling agent.

[0122] Comparative Example 4 Silica-coated aluminum nitride particles A were prepared in Example 1 without the CVD treatment and ammonia treatment, and without the silane coupling agent treatment due to the integral method.

[0123] (Comparative Example 5) The same procedures as in Example 1 were carried out except that the CVD treatment and ammonia treatment were not carried out, the mixing method of the silane coupling agent was changed from the impregnation method to a dry mixing method, and the charging ratio of the silane coupling agent was changed to 3, thereby obtaining a sample of silica-coated aluminum nitride particles A in which silica-coated aluminum nitride particles A were surface-treated with a silane coupling agent.

[0124] (Comparative Example 6) In Example 1, the CVD treatment and ammonia treatment were not performed, the silane coupling agent was changed from KBM-3103 to SZ-31, and the charging ratio of the silane coupling agent was changed to 5. The same procedure as in Example 1 was repeated to obtain a sample of silica-coated aluminum nitride particles A in which silica-coated aluminum nitride particles A were surface-treated with a silane coupling agent.

[0125] (Comparative Example 7) In Example 1, the same procedure as in Example 1 was repeated except that the ammonia treatment was not performed, the silane coupling agent was changed from KBM-3103 to SZ-31, and the charging ratio of the silane coupling agent was changed to 5, thereby obtaining a sample of silica-coated aluminum nitride particles A in which silica-coated aluminum nitride particles A were surface-treated with a silane coupling agent.

[0126] (Comparative Example 8) A sample was obtained in the same manner as in Example 9, except that the silica-coated aluminum nitride particles B were used without being subjected to the CVD treatment, ammonia treatment, or silane coupling agent treatment.

[0127] (Comparative Example 9) In Example 1, the silica-coated aluminum nitride particles A were treated with silica-coated aluminum nitride particles B without CVD treatment or ammonia treatment, and the charging ratio of the silane coupling agent was set to 2. The same procedure as in Example 1 was repeated to obtain a sample of silica-coated aluminum nitride particles B, in which the silica-coated aluminum nitride particles A were surface-treated with a silane coupling agent.

[0128] (Comparative Example 10) In Example 1, the silica-coated aluminum nitride particles A were not subjected to the CVD treatment or ammonia treatment of the boron nitride particles A, and the charging ratio of the silane coupling agent was set to 2. The same procedure as in Example 1 was repeated to obtain a sample of boron particles A in which the boron nitride particles A were surface-treated with a silane coupling agent.

[0129] (Comparative Example 11) In Example 1, the silica-coated aluminum nitride particles A were treated with boron nitride particles B without CVD treatment or ammonia treatment, and the charging ratio of the silane coupling agent was set to 2. The same procedure as in Example 1 was repeated to obtain a sample of boron nitride particles B in which the boron nitride particles B were surface-treated with a silane coupling agent.

[0130] [Measurement of carbon atom content (ΔT-C)] The carbon atom content of the samples obtained in the examples and comparative examples was measured using a carbon / sulfur analyzer (Carbon Analyzer EMIA-821, manufactured by Horiba, Ltd.) that uses a tubular electric furnace and non-dispersive infrared absorption method. Samples were measured before and after (silanol group introduction and subsequent surface treatment). The carbon increment (mass%) during the silanol group introduction and subsequent surface treatment processes was taken as ΔT-C. The carbon increment value was used as a guide for the amount of surface treatment agent attached. The results are shown in Tables 1 and 2.

[0131] [Measurement of slurry flow viscosity] Examples 1 to 8, 12 and Comparative Examples 1 to 3, 5 to 7 Each of the particles obtained in Examples 1-8, 12, and Comparative Examples 1-3, 5-7, aluminum nitride particles TFZ-S30P, alumina particles AA-3, alumina particles AA-18, zinc oxide HD-01, silicone oil TSF458-50, and silicone resin raw material EG-3100(A) were placed in a 150 ml dedicated plastic container to obtain the slurry compositions (parts by mass) listed in Tables 1 and 2. The mixture was stirred and mixed using a planetary-rotating mixer (Thinky Corporation, product name: ARV-310P) at 1500 rpm for 30 seconds six times and at 2000 rpm for 30 seconds three times while reducing the pressure to obtain slurries. The flow viscosity of the resulting slurries was measured using a flow tester (Shimadzu Corporation, model name: "CFT-EX") with a nozzle diameter of 2 mm and a pressure of 2 mm at 30°C and a load of 40 kg. The results are shown in Tables 1 and 2. Details of each component are as follows: TFZ-S30P: Insulating aluminum nitride thermally conductive filler (product name: Toyal Tech Filler, manufactured by Toyo Aluminum Co., Ltd., D50 = 30 μm) AA-3: High-purity alumina (trade name: Advanced Alumina (registered trademark), manufactured by Sumitomo Chemical Co., Ltd., D50 = 3 μm) AA-18: High-purity alumina (product name: Advanced Alumina, manufactured by Sumitomo Chemical Co., Ltd., D50 = 18 μm) HD-01: Zinc oxide (product name: developed product, manufactured by Hakusui Tech Co., Ltd., D50=0.5μm) TSF458-50: Heat-resistant oil (product name: Straight silicone oil, manufactured by Momentive Corporation) EG-3100(A): Liquid A of silicone resin raw material (trade name: DOWSIL (registered trademark) EG-3100, manufactured by Dow-Toray Industries, Inc.) (viscosity 420 mPa·s, mixture of vinyl oil and platinum catalyst) Comparative Example 4 Of the slurry compositions (parts by mass) listed in Table 2, the liquid components, silicone resin raw material EG-3100(A) and silicone oil TSF458-50, and a quantity of silane coupling agent KBM3103 three times the amount required to cover 43.6 parts of nitride filler calculated from the minimum coverage area listed in Example 1, were placed in a 150 ml dedicated plastic container, and stirred once for 30 seconds at a rotation / revolution mixer (manufactured by Thinky Corporation, product name: ARV-310P) at a rotation speed of 2000 rpm. To this mixture were added the particles of Comparative Example 4, aluminum nitride particles TFZ-S30P, alumina particles AA-3, alumina particles AA-18, and zinc oxide HD-01 to obtain the slurry composition (parts by mass) shown in Table 2. Using a rotation-revolution mixer (Thinky Corporation, product name: ARV-310P), the mixture was stirred and mixed at 1500 rpm for 30 seconds six times and at 2000 rpm for 30 seconds three times while reducing the pressure to obtain a slurry. The flow viscosity of the resulting slurry was measured using a flow tester (Shimadzu Corporation, model name: "CFT-EX") with a nozzle diameter of 2 mm and a pressure of 2 mm at 30°C under a load of 40 kg. The results are shown in Table 2. The details of each component in Comparative Example 4 were the same as those described in Examples 1 to 8 and 12 and Comparative Examples 1 to 3 and 5 to 7.

[0132] Example 9 and Comparative Examples 8 to 9 Each of the particles obtained in Example 9 and Comparative Examples 8-9, high-purity alumina AKP-30, and silicone resin raw material EG-3100(A) were placed in a 150 ml dedicated plastic container to obtain the slurry compositions (parts by mass) listed in Tables 1 and 2. The mixture was stirred and mixed under reduced pressure using a planetary centrifugal mixer (Thinky Corporation, product name: ARV-310P) at 1500 rpm for 30 seconds six times and at 2000 rpm for 30 seconds three times to obtain a slurry. The flow viscosity of the resulting slurry was measured using a flow tester (Shimadzu Corporation, model name: "CFT-EX") with a nozzle diameter of 2 mm and pressure of 2 mm, at 30°C, and under a load of 40 kg. The results are shown in Tables 1 and 2. Details of each component are as follows: AKP-30: High-purity alumina (product name: AKP series, manufactured by Sumitomo Chemical Co., Ltd., D50 = 0.26 μm) EG-3100(A): Liquid A of silicone resin raw material (trade name: DOWSIL (registered trademark) EG-3100, manufactured by Dow-Toray Industries, Inc.) (viscosity 420 mPa·s, mixture of vinyl oil and platinum catalyst)

[0133] Example 10 and Comparative Example 10 Each of the particles obtained in Example 10 and Comparative Example 10 and silicone oil (product name: KF-96-1000cs, manufactured by Shin-Etsu Chemical Co., Ltd.) were placed in a 150 ml dedicated plastic container so as to obtain the slurry compositions (parts by mass) listed in Tables 1 and 2. The mixture was stirred and mixed under reduced pressure using a planetary centrifugal mixer (manufactured by Thinky Corporation, product name: ARV-310P) at 1500 rpm for 30 seconds once and at 2000 rpm for 30 seconds twice to obtain a slurry. The flow viscosity of the resulting slurry was measured using a flow tester (manufactured by Shimadzu Corporation, model name: "CFT-EX") with a nozzle diameter of 0.5 mm and a pressure of 1 mm at 30°C under an 80 kg load. The results are shown in Tables 1 and 2.

[0134] Example 11 and Comparative Example 11 Each of the particles obtained in Example 11 and Comparative Example 11 and silicone oil (product name: KF-96-1000cs, manufactured by Shin-Etsu Chemical Co., Ltd.) were placed in a 150 ml dedicated plastic container so as to obtain the slurry composition (parts by mass) shown in Tables 1 and 2. Using a planetary centrifugal mixer (manufactured by Thinky Corporation, product name: ARV-310P), the mixture was stirred and mixed at 1500 rpm for 30 seconds three times while reducing the pressure to obtain a slurry. The flow viscosity of the resulting slurry was measured using a flow tester (manufactured by Shimadzu Corporation, model name: "CFT-EX") with a nozzle diameter of 0.5 mm and a diameter of 1 mm, at 30°C, and under a load of 60 kg. The results are shown in Tables 1 and 2.

[0135] [Measurement of the average surface density of silanol groups] The average surface density of silanol groups of each sample obtained in the Examples and Comparative Examples was measured as follows. First, 1 g of sample was uniformly dispersed in a solution consisting of 25 ml of chloroform and 2 ml of pyridine. Next, 0.1 mg of trifluoroacetic anhydride was added to the resulting dispersion and stirred at 20°C for 1 hour, and then at 40°C for 2 hours to allow for a sufficient reaction. After that, the solid was filtered off and dried at 120°C for 2 hours. The sample after the above treatment was subjected to X-ray photoelectron spectroscopy using a photoelectron spectrometer (model: JPS-9030, manufactured by JEOL Ltd.) to quantify the fluorine atoms. From the number of moles present, the number of silanol groups per unit area was calculated as the average surface density of silanol groups (number / nm 2 The results are shown in Tables 1 and 2.

[0136] [Table 1]

[0137] [Table 2]

[0138] [Table 3]

[0139] [Table 4]

[0140] [Table 5]

[0141] In Examples 1 to 9 (using aluminum nitride particles as the nitride filler), in step 2A of the manufacturing method for nitride fillers coated with organosilicon-containing compounds having silanol groups, or in step 2B of the manufacturing method for silica-coated nitride fillers coated with organosilicon-containing compounds having silanol groups, the immersion method, vapor phase film formation method, or vapor phase simultaneous film formation method was carried out as a basic substance treatment method, and then surface treatment was carried out, thereby coating the nitride filler surface uniformly with more surface treatment agent, thereby controlling the slurry flow viscosity low and enabling the nitride filler to be mixed at a high filling rate. On the other hand, in Comparative Examples 1 to 9, which do not employ at least the immersion method, the vapor-phase film-forming method, or the vapor-phase simultaneous film-forming method as a basic substance treatment method (do not have silanol groups), even when surface treatment is performed, the slurry flow viscosity is high and cannot be controlled low, and it is therefore not possible to mix nitride filler at a high filling rate. Furthermore, compared to Examples 10 and 11 (using boron nitride particles as nitride filler) in which treatment with an organic silicone compound was followed by vapor deposition using a basic substance, Comparative Examples 10 and 11 in which untreated boron nitride was used had a high slurry viscosity, and it was found that the nitride filler could not be mixed at a high filling rate. Furthermore, it is clear that the average surface density of silanol groups on the surfaces of the fillers (filler types) in Examples 1 to 11 is higher than the average surface density of silanol groups on the surfaces of the fillers (filler types) in Comparative Examples 1 to 11. The silanol groups on the filler surface are likely to bond with the silane coupling agent through condensation, which is presumed to efficiently bring out the inherent performance of the silane coupling agent and contribute to reducing the slurry flow viscosity.

Claims

1. A method for producing a nitride filler coated with an organosilicon-containing compound having a silanol group, the method comprising: a nitride filler; and an organosilicon-containing compound coating film covering the surface of the nitride filler and having a silanol group on the surface, the method comprising: The method includes a step 1A of covering the surface of the nitride filler with an organosilicon compound having a structure represented by the following general formula (1) to obtain an organosilicon-containing compound-coated nitride filler covered with the organosilicon compound, and a step 2A of treating the surface of the organosilicon-containing compound-coated nitride filler with a basic substance to obtain an organosilicon-containing compound-coated nitride filler having silanol groups on its surface: Or, A method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups, comprising a first process P in which an organosilicon compound having a structure represented by the following general formula (1) and a basic substance are allowed to coexist in the same atmosphere, the organosilicon compound and the basic substance are treated simultaneously, and the surface of the nitride filler is covered, thereby obtaining an organosilicon-containing compound-coated nitride filler having silanol groups on the surface. 【Chemistry 1】 (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.)

2. 2. The method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to claim 1, wherein in step 2A, the basic substance is aqueous ammonia, and the treatment is carried out by immersion in the aqueous ammonia.

3. 2. The method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to claim 1, wherein in step 2A, the basic substance is aqueous ammonia, and the treatment is carried out by a chemical vapor deposition (CVD) method.

4. 2. The method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to claim 1, wherein in the first P step, the basic substance is aqueous ammonia, and the treatment is carried out simultaneously with the organosilicon compound by chemical vapor deposition (CVD).

5. 2. The method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to claim 1, wherein the nitride filler is aluminum nitride particles or boron nitride particles.

6. 6. The method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to claim 5, wherein the aluminum nitride particles have a particle size (D50) of 0.1 μm or more and 200 μm or less in terms of cumulative volume 50%.

7. 2. The method for producing a nitride filler coated with an organosilicon-containing compound having silanol groups according to claim 1, wherein a surface treatment agent is attached to the surface of the nitride filler coated with an organosilicon-containing compound having silanol groups by reaction or interaction.

8. 8. The method for producing a nitride filler coated with an organosilicon-containing compound having a silanol group according to claim 7, wherein the surface treatment agent is a silane coupling agent.

9. a nitride filler, and a surface of the nitride filler that covers the surface of the nitride filler and has a density of 0.5 to 2.1 particles / nm ２ and a coating of an organosilicon-containing compound having silanol groups present at an average surface density of 1000 to 15000.

10. 10. The nitride filler coated with an organosilicon-containing compound having silanol groups according to claim 9, further comprising a surface treatment agent on the surface of the nitride filler coated with an organosilicon-containing compound having silanol groups.

11. 11. The nitride filler coated with an organosilicon-containing compound having a silanol group according to claim 10, wherein the surface treatment agent is a silane coupling agent.

12. A method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups, the method comprising: a silica-coated nitride filler; and an organosilicon-containing compound coating film covering the surface of the silica-coated nitride filler and having silanol groups on the surface, the method comprising: The method comprises a first step B of covering the surface of the silica-coated nitride filler with an organosilicon compound having a structure represented by the following general formula (1) to obtain an organosilicon-containing compound-coated silica-coated nitride filler coated with the organosilicon compound, and a second step B of treating the surface of the organosilicon-containing compound-coated silica-coated nitride filler with a basic substance to obtain an organosilicon-containing compound-coated silica-coated nitride filler having silanol groups on its surface: Or, A method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having silanol groups, comprising the step of: bringing an organosilicon compound having a structure represented by the following general formula (1) and a basic substance into the same atmosphere; treating the organosilicon compound and the basic substance simultaneously; covering the surface of the silica-coated nitride filler; and obtaining an organosilicon-containing compound-coated silica-coated nitride filler having silanol groups on its surface. 【Chemistry 2】 (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.)

13. 13. The method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to claim 12, wherein in step 2B, the basic substance is aqueous ammonia, and the treatment is carried out by immersion in the aqueous ammonia.

14. 13. The method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to claim 12, wherein in step 2B, the basic substance is aqueous ammonia, and the treatment is carried out by a chemical vapor deposition (CVD) method.

15. 13. The method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to claim 12, wherein in the first Q step, the basic substance is aqueous ammonia, and the treatment is carried out simultaneously with the organosilicon compound by chemical vapor deposition (CVD).

16. 13. The method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to claim 12, wherein the silica-coated nitride filler is silica-coated aluminum nitride particles or silica-coated boron nitride particles.

17. A method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group as described in claim 16, wherein the cumulative volume 50% particle size (D50) of the silica-coated aluminum nitride particles is 0.1 μm or more and 200 μm or less.

18. 13. A method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to claim 12, wherein a surface treatment agent is attached to the surface of the silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group by reaction or interaction.

19. 19. The method for producing a silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to claim 18, wherein the surface treatment agent is a silane coupling agent.

20. a silica-coated nitride filler; and a silica-coated nitride filler having a surface covering the silica-coated nitride filler and a surface having 0.5 to 2.1 particles / nm ２ and a coating of an organosilicon-containing compound having silanol groups present at an average surface density of 1000 to 15000.

21. The silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to claim 20, further comprising a surface treatment agent on the surface of the silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group.

22. 22. The silica-coated nitride filler coated with an organosilicon-containing compound having a silanol group according to claim 21, wherein the surface treatment agent is a silane coupling agent.

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