Method for producing organosilicon-containing compound-coated aluminum nitride particles, and method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles

Abstract

To provide a method for producing organosilicon-containing compound-coated aluminum nitride particles capable of controlling the viscosity of slurry obtained by mixing with a resin monomer, and to provide a method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles capable of controlling the viscosity of slurry obtained by mixing with a resin monomer.SOLUTION: A method for producing organosilicon-containing compound-coated aluminum nitride particles includes a 1A step of coating surfaces of aluminum nitride particles with an organosilicon compound having a specific structure to obtain aluminum nitride particles coated with the organosilicon compound. Alternatively, a method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles includes a 1B step of coating a surface of silica-coated aluminum nitride particles with an organosilicon compound having a specific structure to obtain silica-coated aluminum nitride particles coated with the organosilicon compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing organosilicon-containing compound-coated aluminum nitride particles, and a method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles. Regarding. [Background technology]

[0002] Aluminum nitride has high thermal conductivity and excellent electrical insulation properties. Therefore, it is a promising filler for resin compositions used in products such as heat dissipation sheets and encapsulants for electronic components. However, aluminum nitride undergoes hydrolysis upon reaction with moisture, transforming into aluminum hydroxide, which has low thermal conductivity. Furthermore, aluminum nitride also generates corrosive ammonia during hydrolysis.

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

[0004] Techniques to improve the moisture resistance of aluminum nitride include methods for forming a layer of Si-Al-ON on the surface of aluminum nitride powder (see, for example, Patent Document 1), methods for forming a coating layer on the surface of aluminum nitride powder with a silicate treatment agent and a coupling agent (see, for example, Patent Document 2), methods for treating with a silicate treatment agent and leaving organic groups on the surface of aluminum nitride powder (see, for example, Patent Document 3), and methods for surface modifying the surface of aluminum nitride particles using a specific acidic phosphate ester (see, for example, Patent Document 4). Furthermore, improved methods that maintain even better moisture resistance and thermal conductivity have been proposed (see, for example, Patent Document 5).

[0005] The moisture-resistant aluminum nitride powder described in Patent Document 1 has a Si-Al-ON layer formed on its surface by applying a silicate ester layer to the surface of the aluminum nitride powder and then firing it at a high temperature of 350 to 1000°C. The aluminum nitride-based powder described in Patent Document 2 has a coating layer formed on its surface by surface treatment with a silicate treatment agent and a coupling agent followed by high-temperature heat treatment. The aluminum nitride powder described in Patent Document 3 has improved compatibility with resins by leaving organic groups after surface treatment with a silicate treatment agent and then heat treatment at a temperature not exceeding 90°C. The surface-modified particles described in Patent Document 4 have improved moisture resistance by surface-modifying aluminum nitride particles using a specific acidic phosphate ester. The surface-modified particles described in Patent Document 5 are excellent moisture-resistant aluminum nitride particles coated with an extremely thin, homogeneous, and dense silica film. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 3446053 [Patent Document 2] Patent No. 4088768 [Patent Document 3] Patent No. 4804023 [Patent Document 4] Japanese Patent Publication No. 2015-71730 [Patent Document 5] International Publication No. 2020 / 040309 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, while Patent Documents 1 to 5 have attempted to improve the moisture resistance of aluminum nitride powder as described above, they generally have challenges in terms of compatibility with resins and reducing the viscosity of slurries when mixed with resin monomers or oligomers. In particular, further improvements in compatibility are required when mixing aluminum nitride powder at high packing rates.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a method for producing organosilicon-containing compound-coated aluminum nitride particles in which the viscosity of the slurry obtained by mixing with a resin monomer can be controlled, and a method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles in which the viscosity of the slurry obtained by mixing with a resin monomer can be controlled. [Means for solving the problem]

[0009] As a result of diligent research by the inventors, we have found that the above problems can be solved by coating aluminum nitride particles or silica-coated aluminum nitride particles with a specific organosilicon compound using a specific method, and have completed the present invention. That is, the present invention has the following configuration.

[0010] [1] A method for producing organosilicon-containing compound coated aluminum nitride particles, comprising aluminum nitride particles and an organosilicon-containing compound coating covering the surface of the aluminum nitride particles, the method comprising a first A step of covering the surface of the aluminum nitride particles with an organosilicon compound having a structure represented by the following formula (1) to obtain the aluminum nitride particles covered with the organosilicon compound. [ka] (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.) [2] A method for producing organosilicon-containing compound-coated aluminum nitride particles according to [1], further comprising step 2A of heating the aluminum nitride particles coated with the organosilicon compound at a temperature of less than 300°C. [3]A method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles, comprising silica-coated aluminum nitride particles and an organosilicon-containing compound film covering the surface of the silica-coated aluminum nitride particles, the method comprising: covering the surface of the silica-coated aluminum nitride particles with an organosilicon compound having a structure represented by the following formula (1), and obtaining the silica-coated aluminum nitride particles covered with the organosilicon compound in a first B step, the method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles. [Chemical formula] (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.) [4] The method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles according to [3] above, further comprising a second B step of heating the silica-coated aluminum nitride particles covered with the organosilicon compound at a temperature below 300°C. [Advantages of the Invention]

[0011] According to the present invention, a method for producing organosilicon-containing compound-coated aluminum nitride particles capable of controlling the viscosity of a slurry obtained by mixing with a resin monomer, and a method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles capable of controlling the viscosity of a slurry obtained by mixing with a resin monomer can be provided. [Embodiments for Carrying out the Invention]

[0012] Hereinafter, the present invention will be described in detail. Any arbitrarily selected embodiment or any arbitrarily combined embodiment of the matters described in this specification is also included in the present invention. In this specification, the provisions defined as preferable can be arbitrarily selected, and a combination of the provisions defined as preferable can be said to be more preferable. In this specification, the description "XX to YY" means "XX or more and YY or less". In this specification, the lower and upper limits described in steps for a preferred numerical range (e.g., range of content, etc.) can be combined independently. For example, from the description "preferably 10 to 90, more preferably 30 to 60", the "preferred lower limit (10)" and the "more preferred upper limit (60)" can be combined to arrive at "10 to 60".

[0013] In this specification, "50% cumulative volume particle size (D50)" refers to the particle size at which the cumulative volume of a given particle size distribution reaches 50%. D50 is determined from the particle size distribution by laser diffraction scattering. Specifically, it can be measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac-Bell Co., Ltd., product name: Microtrac MT3300EX2), etc.

[0014] <Method for producing aluminum nitride particles coated with organosilicon-containing compounds> The present invention provides a method for producing organosilicon-containing compound-coated aluminum nitride particles, comprising aluminum nitride particles and an organosilicon-containing compound coating covering the surface of the aluminum nitride particles, characterized in that it includes a first A step of covering the surface of the aluminum nitride particles with an organosilicon compound having a structure represented by the following formula (1), thereby obtaining the aluminum nitride particles coated with the organosilicon compound. [ka] (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.)

[0015] [1st A process] In this process, the surface of aluminum nitride particles is covered with an organosilicon compound containing the structure shown in formula (1) above, thereby obtaining the aluminum nitride particles covered with the organosilicon compound.

[0016] <Aluminum Nitride Particles> In the method for producing organosilicon-containing compound-coated aluminum nitride particles of the present invention, commercially available or other known aluminum nitride particles can be used as raw materials. There are no particular limitations on the method for producing aluminum nitride particles. Examples include the direct nitriding method, which involves directly reacting metallic aluminum powder with nitrogen or ammonia, and the reductive nitriding method, which involves heating alumina under a nitrogen or ammonia atmosphere while simultaneously performing a nitriding reaction.

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

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

[0019] The oxygen content mentioned above 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, and hydrogen analyzer (ONH836: manufactured by LECO Japan LLC), etc.

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

[0021] The shape of the aluminum nitride particles used in this invention is not particularly limited, and examples include amorphous (crushed), spherical, elliptical, and plate-like (scaly). Furthermore, when organosilicon-containing compound-coated aluminum nitride particles are dispersed and included in a resin composition as a filler, only aluminum nitride particles of the same type having the same shape and structure (a single substance) may be used as the aluminum nitride particles, but it is also possible to use a mixture of aluminum nitride particles obtained by mixing two or more different types of aluminum nitride particles having different shapes and structures in various proportions.

[0022] When organosilicon-containing compound-coated aluminum nitride particles are dispersed and included in a resin composition, the higher the volume ratio (filling amount) of the aluminum nitride particles constituting the organosilicon-containing compound-coated aluminum nitride particles to the resin composition, the higher the thermal conductivity of the resin composition. Therefore, it is preferable that the shape of the aluminum nitride particles be close to a spherical shape, which minimizes the increase in viscosity of the resin composition due to the addition of organosilicon-containing compound-coated aluminum nitride particles.

[0023] There are no particular restrictions on the 50% cumulative volume particle size (D50) of the aluminum nitride particles used in the present invention, but it is preferably 0.5 μm or more, more preferably 0.5 μm to 200.0 μm, even more preferably 0.8 μm to 100.0 μm, and particularly preferably 1.0 μm to 80.0 μm.

[0024] When the D50 of the aluminum nitride particles is within the range described above, even when using a resin composition containing organosilicon-containing compound-coated aluminum nitride particles as a heat dissipation material for mounting power system electronic components, it becomes possible to supply a heat dissipation material with the minimum thickness, and the moisture resistance of the aluminum nitride particles is further improved, possibly because the coating is more likely to uniformly cover the surface of the aluminum nitride particles.

[0025] <Organosilicone compounds used for coating> In the method for producing organosilicon-containing compound-coated aluminum nitride particles of the present invention, the organosilicon compound used as a raw material for the organosilicon-containing compound coating constituting the organosilicon-containing compound-coated aluminum nitride particles is an organosilicon compound containing the structure shown in formula (1) above. It can be used without particular limitation regardless of whether it is linear, cyclic, or branched in form. The structure represented by formula (1) is a hydrogen siloxane unit in which hydrogen is directly bonded to a silicon atom.

[0026] In formula (1) above, R, which is an alkyl group having 1 to 4 carbon atoms, is preferably a methyl group, ethyl group, propyl group, t-butyl group, etc., from the viewpoint of volatilizing the silicone compound, and is particularly preferably a methyl group. In the method for producing organosilicon-containing compound-coated aluminum nitride particles of the present invention, the organosilicon compound used as a raw material is, for example, an oligomer or polymer containing the structure shown in formula (1).

[0027] As the organosilicon compound, at least one of the compounds represented by formula (2) below and the compounds represented by formula (3) below is preferred. [ka] (In formula (2), R1 and R2 are independently either a hydrogen atom or a methyl group, at least one of R1 and R2 is a hydrogen atom, and m is an integer between 0 and 10.)

[0028] [ka] (In equation (3), n is an integer between 3 and 6.)

[0029] In particular, the cyclic hydrogensiloxane oligomer in formula (3) where n is 4 is excellent in that it can form a uniform film on the surface of aluminum nitride particles. The weight-average molecular weight of the organosilicon 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 using an organosilicon compound containing the structure shown in formula (1) with a weight-average molecular weight in this range makes it easier to form a thin and uniform film on the surface of aluminum nitride particles. In formula (2), it is preferable that m is 1.

[0030] In this specification, weight-average molecular weight is the polystyrene-based weight-average molecular weight obtained by gel permeation chromatography (GPC), and specifically, it can be measured using a combination of a column (Shodex® LF-804: manufactured by Showa Denko K.K.) and a differential refractive index detector (Shodex® RI-71S: manufactured by Showa Denko K.K.).

[0031] In step 1A, the surface of the aluminum nitride particles is covered with an organosilicone compound containing the structure shown in formula (1). In step 1A, the method is not particularly limited as long as the surface of the aluminum nitride particles can be covered with an organosilicone compound containing the structure shown in formula (1). Examples of methods for step 1 include a dry mixing method in which the organosilicone compound is added by spraying or other means while stirring the raw material aluminum nitride particles using a general powder mixing apparatus, and then dry-mixed to coat the particles. Examples of powder mixing apparatuses include Henschel mixers, container-rotating V-blenders, double-cone blenders, ribbon blenders with mixing blades, screw blenders, sealed rotary kilns, and stirring using a stirrer in a sealed container with a magnetic coupling. The temperature conditions in this case are not particularly limited, depending on the boiling point and vapor pressure of the silicone compound containing the structure shown in formula (1), but 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.

[0032] Furthermore, as a method for step 1A, a gas-phase adsorption method can be used in which a vapor of an organosilicon compound containing the structure shown in formula (1), or a mixed gas with an inert gas such as nitrogen gas, is attached to or deposited onto the surface of the standing aluminum nitride particles. In this case, the temperature conditions are not particularly limited, depending on the boiling point and vapor pressure of the silicone compound containing the structure shown in formula (1), but 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. If necessary, the system can also be pressurized or depressurized. In this case, a sealed system that allows for easy replacement of the gas in the system is preferred, such as a glass container, desiccator, or CVD apparatus. When coating aluminum nitride particles with an organosilicon compound without stirring, the processing time needs to be longer. However, by intermittently placing the processing container on a vibrator, even areas where powder particles are in contact and shaded, or powder particles far from the upper air layer, can be efficiently processed by moving the position.

[0033] The amount of the organosilicon compound containing the structure shown in formula (1) used in step 1A is not particularly limited. In the aluminum nitride particles coated with the organosilicon compound containing the structure shown in formula (1) obtained in step 1A, the amount of coating with the organosilicon compound containing the structure shown in formula (1) is equal to the specific surface area (m²) of the aluminum nitride particles determined by the BET method. 2 Surface area 1 m² calculated from ( / g) 2 The amount is preferably 0.08 mg to 20.0 mg per serving, more preferably 0.09 mg to 15.0 mg, and even more preferably 1.0 mg to 10.0 mg. Furthermore, the specific surface area (m²) of the above aluminum nitride particles obtained by the BET method 2 Surface area 1 m² calculated from ( / g) 2 The amount of organic silicone compound coating per unit containing the structure shown in equation (1) is calculated by taking the mass difference of the aluminum nitride particles before and after coating with the organic silicone compound and determining the specific surface area (m²) of the aluminum nitride particles using the BET method. 2 Surface area (m²) calculated from g / g 2 It can be found by dividing by ). The specific surface area obtained from the BET method can be measured using the nitrogen adsorption BET single-point method based on gas flow. A Macsorb HM model-1210 from Mounttech can be used as the evaluation device.

[0034] [2nd A process] A method for producing organosilicon-containing compound-coated aluminum nitride particles may include a second A step in which the aluminum nitride particles coated with the organosilicon compound are further heated at a temperature of less than 300°C. In this step, it is preferable to heat-treat the aluminum nitride particles covered with the organosilicon compound obtained in step 1A at a temperature of less than 300°C. This heat treatment makes it easier to control the desired amount of active hydrogen groups remaining. The amount of active hydrogen is highest without heat treatment, and as the heating temperature increases, the amount of active hydrogen decreases, almost disappearing at temperatures above 300°C. It is thought that the active hydrogen groups react and bond with, for example, the vinyl groups of the silicone resin monomer, increasing their affinity for the silicone resin monomer and leading to a decrease in slurry viscosity. Therefore, it is presumed that particles heated at temperatures above 300°C, where the active hydrogen groups have disappeared, will become thicker due to decreased compatibility. Furthermore, while the active hydrogen groups are intended to react with the vinyl groups of the silicone resin monomer, in the case of oligomers with relatively large monomer molecular weights, there may be too many active hydrogen groups, resulting in an excessive thickening effect. In such cases, increasing the heat treatment temperature in step 2A can be used to suppress the increase in slurry viscosity or to control it to the optimal point where the slurry viscosity is minimized. The heat treatment time is preferably in the range of 30 minutes to 6 hours, more preferably in the range of 45 minutes to 4 hours, and even more preferably in the range of 1 hour to 3 hours.

[0035] <Method for producing silica-coated aluminum nitride particles coated with organosilicon-containing compounds> The present invention provides a method for producing silica-coated aluminum nitride particles coated with an organosilicon-containing compound, comprising: silica-coated aluminum nitride particles; and an organosilicon-containing compound coating covering the surface of the silica-coated aluminum nitride particles, characterized in that it includes a first B step of covering the surface of the silica-coated aluminum nitride particles with an organosilicon compound having a structure represented by the following formula (1), thereby obtaining the silica-coated aluminum nitride particles coated with the organosilicon compound. [ka] (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.)

[0036] [1B process] In this process, the surface of silica-coated aluminum nitride particles is covered with an organosilicone compound containing the structure shown in formula (1) above, thereby obtaining the silica-coated aluminum nitride particles covered with the organosilicone compound.

[0037] <Aluminum Nitride Particles> In the method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles of the present invention, the aluminum nitride particles used as raw materials can be the same as the aluminum nitride particles that constitute the organosilicon-containing compound-coated aluminum nitride particles described above.

[0038] <Silica-coated aluminum nitride particles> In the method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles of the present invention, the silica-coated aluminum nitride particles used as raw materials can be prepared using the above-mentioned aluminum nitride, for example, by the method described in International Publication No. 2020 / 040309

[0040] to

[0061] .

[0039] <Organosilicone compounds used for coating> In the method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles of the present invention, the organosilicon compound used as a raw material for the organosilicon-containing compound coating constituting the organosilicon-containing compound-coated silica-coated aluminum nitride particles is an organosilicon compound containing the structure shown in formula (1) above. It can be used without particular limitation regardless of whether it is linear, cyclic, or branched in form. The structure represented by formula (1) is a hydrogen siloxane unit in which hydrogen is directly bonded to a silicon atom.

[0040] In formula (1) above, R, which is an alkyl group having 1 to 4 carbon atoms, is preferably a methyl group, ethyl group, propyl group, t-butyl group, etc., from the viewpoint of volatilizing the silicone compound, and is particularly preferably a methyl group. In the method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles of the present invention, the organosilicon compound used as a raw material is, for example, an oligomer or polymer containing the structure shown in formula (1).

[0041] As the organosilicon compound, at least one of the compounds represented by formula (2) below and the compounds represented by formula (3) below is preferred. [ka] (In formula (2), R1 and R2 are independently either a hydrogen atom or a methyl group, at least one of R1 and R2 is a hydrogen atom, and m is an integer between 0 and 10.)

[0042] [ka] (In equation (3), n is an integer between 3 and 6.)

[0043] In particular, the cyclic hydrogensiloxane oligomer in formula (3) where n is 4 is excellent in that it can form a uniform film on the surface of aluminum nitride particles. The weight-average molecular weight of the organosilicon 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 using an organosilicon compound containing the structure shown in formula (1) with a weight-average molecular weight in this range makes it easier to form a thin and uniform film on the surface of silica-coated aluminum nitride particles. In formula (2), it is preferable that m is 1.

[0044] In this specification, weight-average molecular weight is the polystyrene-based weight-average molecular weight obtained by gel permeation chromatography (GPC), and specifically, it can be measured using a combination of a column (Shodex® LF-804: manufactured by Showa Denko K.K.) and a differential refractive index detector (Shodex® RI-71S: manufactured by Showa Denko K.K.).

[0045] In step 1B, the surface of the silica-coated aluminum nitride particles is covered with an organic silicone compound containing the structure shown in formula (1). In step 1B, the method is not particularly limited as long as the surface of the silica-coated aluminum nitride particles can be covered with an organosilicone compound containing the structure shown in formula (1). Examples of methods for step 1B include a dry mixing method in which the organosilicone compound is added by spraying or other means while stirring the raw material aluminum nitride particles using a general powder mixing apparatus, and then dry-mixed to coat the particles. Examples of powder mixing apparatuses include Henschel mixers, container-rotating V-blenders, double-cone blenders, ribbon blenders with mixing blades, screw blenders, sealed rotary kilns, and stirring using a stirrer in a sealed container with a magnetic coupling. The temperature conditions in this case are not particularly limited, depending on the boiling point and vapor pressure of the silicone compound containing the structure shown in formula (1), but a preferred temperature range is 10°C to 200°C, more preferably 20°C to 150°C, and even more preferably 40°C to 100°C.

[0046] Also, as a method for the first B step, a gas-phase adsorption method can be used in which a vapor of an organosilicon compound containing the structure represented by formula (1) alone or a mixed gas with an inert gas such as nitrogen gas is attached or deposited on the surface of the stationary silica-coated aluminum nitride particles. The temperature conditions in this case are not particularly limited depending on the boiling point and vapor pressure of the silicone compound containing the structure represented by formula (1), but the preferred temperature is 10°C or higher and 200°C or lower, more preferably 20°C or higher and 150°C or lower, and even more preferably 40°C or higher and 100°C or lower. Further, if necessary, the pressure inside the system can be increased or decreased. As a device that can be used in this case, a closed system and a device capable of easily replacing the gas inside the system are preferred. For example, a glass container, a desiccator, a CVD device, etc. can be used. When coating the aluminum nitride particles with the organosilicon compound without stirring, the treatment time needs to be taken longer. However, by intermittently placing the treatment container on a vibrator, the powder can be efficiently treated by moving the position even for the powder in the place where the powders are in contact and shaded and the powder far from the upper air layer part.

[0047] The amount of the organosilicon compound containing the structure represented by formula (1) used in the first B step is not particularly limited. In the silica-coated aluminum nitride particles covered with the organosilicon compound containing the structure represented by formula (1) obtained in the first B step, the coating amount of the organosilicon compound containing the structure represented by formula (1) is 0.08 mg or more and 20.0 mg or less per 1 m 2 calculated from the specific surface area (m 2 / g) determined by the BET method of the aluminum nitride particles, preferably in the range of 0.09 mg or more and 15.0 mg or less, and even more preferably in the range of 1.0 mg or more and 10.0 mg or less. Incidentally, per 1 m of the surface area calculated from the specific surface area (m 2 / g) determined by the BET method of the above silica-coated aluminum nitride particles 2The amount of organic silicone compound coating per unit containing the structure shown in equation (1) is calculated by taking the mass difference between the silica-coated aluminum nitride particles before and after coating with the organic silicone compound and the specific surface area (m²) of the silica-coated aluminum nitride particles obtained by the BET method. 2 Surface area (m²) calculated from g / g 2 It can be found by dividing by ). The specific surface area obtained from the BET method can be measured using the nitrogen adsorption BET single-point method based on gas flow. A Macsorb HM model-1210 from Mounttech can be used as the evaluation device.

[0048] [2nd B process] A method for producing silica-coated aluminum nitride particles coated with an organosilicon-containing compound may include a second B step in which the silica-coated aluminum nitride particles, which are covered with the organosilicon compound, are further heated at a temperature of less than 300°C. In this step, it is preferable to heat-treat the silica-coated aluminum nitride particles, which are covered with the organosilicon compound obtained in step 1B, at a temperature of less than 300°C. This heat treatment makes it easier to control the desired amount of active hydrogen groups remaining. As mentioned above, the amount of active hydrogen is highest when no heat treatment is performed, and as the heating temperature increases, the amount of active hydrogen decreases, almost disappearing at temperatures above 300°C. It is thought that the active hydrogen groups react and bond with, for example, the vinyl groups of the silicone resin monomer, increasing their affinity for the silicone resin monomer and leading to a decrease in slurry viscosity. Therefore, it is presumed that particles heated at temperatures above 300°C, where the active hydrogen groups have disappeared, will become thicker due to decreased compatibility. Furthermore, while the active hydrogen groups are intended to react with the vinyl groups of the silicone resin monomer, in the case of oligomers with relatively large monomer molecular weights, there may be too many active hydrogen groups, resulting in an increased viscosity. In such cases, increasing the heat treatment temperature in step 2B can be used to suppress the increase in slurry viscosity or to control it to the optimal point where the slurry viscosity is minimized. The heat treatment time is preferably in the range of 30 minutes to 6 hours, more preferably in the range of 45 minutes to 4 hours, and even more preferably in the range of 1 hour to 3 hours.

[0049] [Method for producing resin compositions] Aluminum nitride particles coated with organosilicon-containing compound obtained in the manufacturing method of the present invention, Alternatively, a resin composition can be produced using silica-coated aluminum nitride particles coated with an organosilicon-containing compound. That is, the method for producing a resin composition in the present invention may include a production step of producing organosilicon-containing compound-coated aluminum nitride particles using the above-mentioned method for producing organosilicon-containing compound-coated aluminum nitride particles, and a mixing step of mixing the organosilicon-containing compound-coated aluminum nitride particles with a resin, or a production step of producing organosilicon-containing compound-coated silica-coated aluminum nitride particles and a mixing step of mixing the organosilicon-containing compound-coated silica-coated aluminum nitride particles with a resin.

[0050] In the mixing step, the organosilicon-containing compound-coated aluminum nitride particles produced by the above-mentioned method for producing organosilicon-containing compound-coated aluminum nitride particles are mixed with a resin. Alternatively, the organosilicon-containing compound-coated silica-coated aluminum nitride particles produced by the above-mentioned method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles are mixed with a resin. The resin to be mixed in the mixing step is not particularly limited, but from the viewpoint of heat resistance, thermosetting resins, thermoplastic resins, or mixtures of thermosetting resins and thermoplastic resins are preferred. From the viewpoint of controlling the viscosity of the slurry, it is preferable that the thermosetting resin has functional groups that can react with active hydrogen groups (e.g., vinyl groups, allyl groups, etc.), or that such groups have been introduced into it. 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, and can be used individually or in combination of two or more types. Furthermore, a mixture of the thermosetting resin with the above-mentioned curing agent and curing accelerator may also be used. In particular, epoxy resins are preferred in terms of good heat resistance, adhesion, and electrical properties after curing, and silicone resins are preferred in applications where flexible adhesion is important.

[0051] Silicone resins include addition-curing type silicone resins, condensation-curing type silicone resins, and organic peroxide-curing type silicone resins, and can be used individually or in combination of two or more types with different viscosities. In particular, when the resulting resin composition is used in applications where flexibility and adhesion are important, an addition-curing type liquid silicone resin that does not produce by-products that can cause bubbles is recommended. A cured silicone resin can be obtained by reacting an organopolysiloxane having alkenyl groups as a base polymer with an organopolysiloxane having Si-H groups as a crosslinking agent at room temperature or by heating in the presence of a curing agent. Specific examples of the organopolysiloxane as a base polymer include those having vinyl groups, allyl groups, propenyl groups, hexenyl groups, etc., as alkenyl groups. Vinyl groups are particularly preferred as organopolysiloxanes. Furthermore, a platinum metal-based curing catalyst can be used as the curing catalyst, and the amount added can be adjusted to achieve the desired hardness of the cured resin.

[0052] Epoxy resins include: difunctional glucidyl 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; glucidyl ester type epoxy resins such as glycidyl hexahydrophthalate and glycidyl dimer acid; 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'-dia Examples include glucidylamine-type epoxy resins such as minodiphenylmethane, 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 epoxy resins described above can be used individually or in combination of two or more types.

[0053] When using the epoxy resin described above, a curing agent and a curing accelerator may be added. Examples of curing agents include alicyclic acid anhydrides such as methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and hymicic anhydride; aliphatic acid anhydrides such as dodecenyl succinic anhydride; aromatic acid anhydrides such as phthalic anhydride and trimellitic anhydride; bisphenols such as bisphenol A, bisphenol F, and bisphenol S; phenol resins such as phenol-formaldehyde resin, phenol-aralkyl resin, naphthol-aralkyl resin, and phenol-dicyclopentadiene copolymer resin; and organic dihydrazides such as dicyandiamide and adipic acid dihydrazide. Examples of curing catalysts include amines such as tris(dimethylaminomethyl)phenol, dimethylbenzylamine, 1,8-diazabicyclo(5,4,0)undecene and their derivatives; and imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole and their derivatives. These can be used individually or in combination of two or more types.

[0054] In the mixing process, in addition to the silicon-containing oxide-coated aluminum nitride particles or the silicon-containing oxide-coated silica-coated aluminum nitride particles, fillers such as boron nitride, alumina, silica, and zinc oxide, which are commonly used, may also be used.

[0055] In the mixing step, the amount of the above-mentioned organosilicon-containing compound-coated aluminum nitride particles and fillers other than the above-mentioned organosilicon-containing compound-coated aluminum nitride particles, or the above-mentioned organosilicon-containing compound-coated silica-coated aluminum nitride particles and fillers other than the above-mentioned organosilicon-containing compound-coated silica-coated aluminum nitride particles, should be mixed in an amount that results in the desired resin composition. The total volume content of the organosilicon-containing compound-coated aluminum nitride particles and fillers other than the organosilicon-containing compound-coated aluminum nitride particles in the resulting resin composition, or the total volume content of the organosilicon-containing compound-coated silica-coated aluminum nitride particles and fillers other than the organosilicon-containing compound-coated silica-coated aluminum nitride particles, 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, good heat dissipation can be achieved, and if it is 99% by volume or less, good workability can be obtained when using the resin composition.

[0056] The volume content of organosilicon-containing compound-coated aluminum nitride particles in the resulting resin composition is preferably 30% to 100% by volume of the total volume content of the organosilicon-containing compound-coated aluminum nitride particles and fillers other than the organosilicon-containing compound-coated aluminum nitride particles, more preferably 40% to 100% by volume, and even more preferably 50% to 100% by volume. A total volume content of 30% or more can exhibit good heat dissipation. Furthermore, the volume content of the organosilicon-containing compound-coated silica-coated aluminum nitride particles in the resulting resin composition is preferably 30% to 100% by volume of the total volume content of the organosilicon-containing compound-coated silica-coated aluminum nitride particles and fillers other than the organosilicon-containing compound-coated silica-coated aluminum nitride particles, more preferably 40% to 100% by volume, and even more preferably 50% to 100% by volume. A total volume content of 30% or more can exhibit good heat dissipation.

[0057] In the mixing process, flexibility-imparting agents such as silicone, urethane acrylate, butyral resin, acrylic rubber, diene rubber and its copolymers, silane coupling agents, titanium coupling agents, inorganic ion scavenging agents, pigments, dyes, diluents, solvents, etc., may be added as needed.

[0058] The mixing method in the mixing process is not particularly limited. For example, the organosilicon-containing compound-coated aluminum nitride particles or organosilicon-containing compound-coated silica-coated aluminum nitride particles, resin, and other additives are mixed together or separately using dispersion and dissolution equipment such as a mixer, planetary mixer, rotation / revolution mixer, kneader, and roll mill, either individually or in appropriate combinations, and heated as needed to mix, dissolve, and knead to obtain a slurry or the like.

[0059] Furthermore, the obtained resin composition can be molded into a sheet and reacted as needed to produce a heat dissipation sheet. The above-described resin composition and heat dissipation sheet can be suitably used for bonding applications such as semiconductor power devices and power modules. [Examples]

[0060] The present invention will now be specifically described with reference to examples, but the present invention is not limited in any way by these examples.

[0061] (Example 1) [Preparation of silica-coated aluminum nitride particles] A vacuum desiccator made of 20mm thick acrylic resin with internal dimensions of 260mm x 260mm x 100mm, and divided into upper and lower sections by a partition with through holes, was used to surface-coat aluminum nitride particles. First, in the upper section of the vacuum desiccator, a particle with a cumulative volume 50% particle size (D50) of 80 μm and a specific surface area of ​​0.07 m² determined by the BET method is placed. 2 30g of aluminum nitride particles A (FAN-f80: manufactured by Furukawa Electronics Co., Ltd.) at a concentration of / g was spread evenly on a stainless steel tray and left to stand. Next, 10 g of organosilicon compound A (2,4,6,8-tetramethylcyclotetrasiloxane: manufactured by Tokyo Chemical Industry Co., Ltd.), where n=4 in equation (3), was placed in a φ1200 glass petri dish and allowed to stand in the lower section of the vacuum desiccator. Furthermore, the vacuum desiccator was sealed and CVD treatment was performed at 80°C for 8 hours using an oven. After that, the sample was transferred to an alumina crucible and heat-treated at 850°C for 6 hours to obtain silica-coated aluminum nitride particles.

[0062] [Preparation of silica-coated aluminum nitride particles coated with organosilicon-containing compounds] 200 g of silica-coated aluminum nitride particles obtained above were placed in an aluminum tray in an 8 L pressure-resistant container made of stainless steel, and set on a raised base made of stainless steel. 11.0 g of organosilicon compound A (2,4,6,8-tetramethylcyclotetrasiloxane: manufactured by Tokyo Chemical Industry Co., Ltd.), where n=4 in formula (3), was placed in a φ50 glass petri dish and then subjected to CVD treatment at 82°C for 4.5 hours in a sealed oven to obtain organosilicon-containing compound-coated silica-coated aluminum nitride particles.

[0063] (Example 2) Except for the fact that 30 g of the organosilicon-containing compound-coated silica-coated aluminum nitride particles obtained in Example 1 were further heat-treated at 100°C, organosilicon-containing compound-coated silica-coated aluminum nitride particles were obtained in the same manner as in Example 1.

[0064] (Example 3) Except for the fact that 30 g of the organosilicon-containing compound-coated silica-coated aluminum nitride particles obtained in Example 1 were further heat-treated at 150°C, organosilicon-containing compound-coated silica-coated aluminum nitride particles were obtained in the same manner as in Example 1.

[0065] (Example 4) Except for the fact that 30 g of the organosilicon-containing compound-coated silica-coated aluminum nitride particles obtained in Example 1 were further heat-treated at 200°C, organosilicon-containing compound-coated silica-coated aluminum nitride particles were obtained in the same manner as in Example 1.

[0066] (Comparative Example 1) Except for the fact that 30 g of the organosilicon-containing compound-coated silica-coated aluminum nitride particles obtained in Example 1 were further heat-treated at 300°C, organosilicon-containing compound-coated silica-coated aluminum nitride particles were obtained in the same manner as in Example 1.

[0067] (Comparative Example 2) Except for the fact that 30 g of the organosilicon-containing compound-coated silica-coated aluminum nitride particles obtained in Example 1 were further heat-treated at 650°C, organosilicon-containing compound-coated silica-coated aluminum nitride particles were obtained in the same manner as in Example 1.

[0068] (Comparative Example 3) In the acrylic desiccator used for the preparation of the silica-coated aluminum nitride particles described above, the D50 was 80 μm and the specific surface area was 0.07 m² as determined by the BET method. 2 Approximately 60 g of aluminum nitride particles A (FAN-f80: manufactured by Furukawa Electronics Co., Ltd.) at a density of / g was placed in an aluminum foil tray and set on a slatted tray. In the lower section, 10 g of an organosilicon compound (2,4,6,8-tetramethylcyclotetrasiloxane: manufactured by Tokyo Chemical Industry Co., Ltd.) with n=4 in formula (3) was placed in a glass petri dish and allowed to stand. The vacuum desiccator was then sealed and subjected to CVD treatment in an 80°C oven for 8 hours. After that, the sample was transferred to an alumina crucible and heat-treated at 650°C for 3 hours to obtain silica-coated aluminum nitride particles.

[0069] [Measurement of coating amount of organic silicone compound] The amount of coating with the organosilicon compounds in Examples 1-4 and Comparative Examples 1-3 was measured using the following procedure. (1) 10cc of a solution made by mixing 98% sulfuric acid (super premium grade, manufactured by Wako Pure Chemical Industries) and deionized water in a 2:1 ratio was placed in a 20cc Teflon container, and 0.5g of each powder immediately after CVD treatment was added thereto. (2) The Teflon container was placed in a stainless steel pressure-resistant jacket and treated at 230°C for 15 hours to completely dissolve the sample. (3) After dissolution, the solution was removed and the silicon concentration was measured using an ICP emission spectrometer (Hitachi, Ltd. PS3520 VDDII). (4) Subtract the silicon concentration of the CVD raw material and convert it to the weight of the organosilicon compound in the equivalent number of moles, divide this by the BET value of the raw material, and calculate the powder surface 1 m 2 Amount of organosilicon compound coating per unit (mg / m 2 ) was used. The results are shown in Table 1.

[0070] [Measurement of relative active hydrogen content] The relative active hydrogen content of the organosilicon-containing compound-coated silica-coated aluminum nitride particles and silica-coated aluminum nitride particles obtained in Examples 1-4 and Comparative Examples 1-3 was measured using the following procedure. (1) 30 g of silica-coated aluminum nitride particles coated with an organosilicon-containing compound, or silica-coated aluminum nitride particles, were mixed with 2.5 g of ATMS (allyltrimethylsilane) manufactured by Shin-Etsu Chemical Co., Ltd. containing 300 ppm chloroplatinic acid. The mixture was then mixed for 30 seconds at a rotation speed of 1500 rpm using a rotation / revolution mixing mixer (manufactured by Shin-Kee Co., Ltd., product name: ARE-310), followed by heat treatment at 120°C for 2 hours to react the active hydrogen groups with the allyl groups. (2) 10 cc of a solution prepared by mixing 98% sulfuric acid (super premium grade, manufactured by Wako Pure Chemical Industries) and deionized water in a 2:1 ratio was added to a 20 cc Teflon container, along with 0.5 g of the sample prepared in (1). (3) The Teflon container was placed in a stainless steel pressure-resistant jacket and treated at 230°C for 15 hours to completely dissolve the sample. (4) After dissolution, the solution was removed and the silicon concentration was measured using an ICP emission spectrometer (Hitachi PS3520 VDDII). (5) The silicon concentration of the raw materials was subtracted to calculate the silicon increase due to the ATMS reaction, and this was used as a relative guideline for the amount of active hydrogen. The results are shown in Table 1.

[0071] [Measurement of slurry flow viscosity] To obtain the slurry composition (parts by mass) shown in Table 1, the organosilicon-containing compound-coated silica-coated aluminum nitride particles obtained in Examples 1-4 and Comparative Examples 1-2, or the silica-coated aluminum nitride particles obtained in Comparative Example 3, along with alumina particles AA-3, alumina particles AKP-30, and silicone resin raw material were set in a 150 ml dedicated poly container. Using a rotation / revolution mixing mixer (manufactured by Thinky Co., Ltd., product name: ARV-310P), the mixture was stirred and mixed under reduced pressure for 30 seconds at 1500 rpm once, and 30 seconds at 2000 rpm three times to obtain a slurry. The flow viscosity of the obtained slurry was measured using a flow tester (manufactured by Shimadzu Corporation, model name: "CFT-EX") under conditions of a nozzle φ2 × 2 mm L, 30°C, and a 20 kg load. The results are shown in Table 1. Details of each component are as follows: AA-3: Advanced Alumina (Product name: Sumicorundum®, manufactured by Sumitomo Chemical Co., Ltd., D50 = 3 μm) • AKP-30: High-purity alumina (Product name: AKP-30, manufactured by Sumitomo Chemical Co., Ltd., D50 = 0.3 μm) • EG-3100(A): Silicone resin raw material (product name: DOWSIL® EG-3100, manufactured by Dow-Toray Industries, Inc.) Solution A (viscosity 420 mPa·s, mixture of vinyl oil and platinum catalyst)

[0072] [Table 1]

[0073] Examples 1 to 4 demonstrate that in the first B step of the method for producing silica-coated aluminum nitride particles coated with an organosilicon-containing compound, by depositing an organosilicon compound containing a specific structure onto the surface of the silica-coated aluminum nitride particles using the CVD method, the slurry flow viscosity can be kept low due to the presence of relative active hydrogen. Furthermore, in the second B step, by increasing the heat treatment temperature to less than 300°C, the slurry flow viscosity can be controlled, and aluminum nitride powder can be mixed with a high packing density. On the other hand, in Comparative Examples 1 and 2, it can be seen that when the heat treatment temperature is increased to 300°C or higher, the relative amount of active hydrogen becomes zero, the slurry flow viscosity increases, and it becomes impossible to mix the aluminum nitride powder at a high packing density. Furthermore, in Comparative Example 3, which does not have an organosilicon-containing compound coating on the silica-coated aluminum nitride particles, when the heat treatment conditions are the same as those of the 2B step in Comparative Example 2, the relative amount of active hydrogen becomes zero, and the slurry flow viscosity also shows a similar value.

Claims

1. A method for producing organosilicon-containing compound-coated aluminum nitride particles, comprising aluminum nitride particles and an organosilicon-containing compound coating covering the surface of the aluminum nitride particles, The first step A includes a method in which an organic silicone compound having a structure shown in the following formula (1) is coated onto the surface of the aluminum nitride particles by a gas-phase adsorption method in which the vapor of the organic silicone compound alone or a mixed gas with an inert gas is attached to or deposited onto the surface of the aluminum nitride particles while they are standing, thereby obtaining the aluminum nitride particles covered with the organic silicone compound. The process includes a second step A, in which the aluminum nitride particles covered with the organic silicone compound are further heated at a temperature of less than 300°C. A method for producing aluminum nitride particles coated with organosilicon-containing compounds. 【Chemistry 1】 (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.)

2. A method for producing silica-coated aluminum nitride particles comprising silica-coated aluminum nitride particles and an organosilicon-containing compound coating covering the surface of the silica-coated aluminum nitride particles, A method for producing silica-coated aluminum nitride particles coated with an organosilicon-containing compound, comprising a first B step of coating the surface of the silica-coated aluminum nitride particles with an organosilicon compound having a structure represented by the following formula (1) to obtain the silica-coated aluminum nitride particles coated with the organosilicon compound. 【Chemistry 2】 (In formula (1), R is an alkyl group having 1 to 4 carbon atoms.)

3. A method for producing organosilicon-containing compound-coated silica-coated aluminum nitride particles according to claim 2, further comprising a second B step of heating the silica-coated aluminum nitride particles covered with the organosilicon compound at a temperature of less than 300°C.

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