TWI574913B - The method of granulating insulating fins and boron nitride - Google Patents

Description

Insulating heat-dissipating sheet and granulation method of boron nitride

The present invention relates to an insulating heat-dissipating sheet which is used for transferring heat to a heat-dissipating member such as an electron, a motor or a light-emitting device, and a granulation method for boron nitride used in the sheet.

Conventionally, heat conduction from a heat generating member such as an electron, a motor, or a light-emitting device to a heat-conducting member of a heat-dissipating member is required to have high thermal conductivity and insulation. A heat-conducting layer that satisfies such requirements is widely used to disperse a filler in a resin or Insulated heat sink sheet made of rubber. Here, the filler is hexagonal boron nitride (h-BN) having high thermal conductivity and insulating properties.

The crystal structure of hexagonal boron nitride is a layered structure similar to that of graphite, and its particle shape is scaly. The scaly boron nitride has a different thermal conductivity, and has high thermal conductivity in the long diameter direction and low thermal conductivity in the short diameter direction, and the difference in thermal conductivity between the long diameter direction and the short diameter direction is considered to be several times to several ten times. Therefore, by making the scaly boron nitride dispersed in the resin or the rubber in an upright state in the sheet, even if the long diameter direction of the scale-like boron nitride matches the thickness direction of the sheet, it is expected to develop the sheet thickness. The thermal conductivity of the direction is greatly improved by the insulating heat sink sheet.

However, in the method of forming into a sheet shape by a known molding method such as a calendering method, an injection molding method, an extrusion molding method, a calender molding method, a roll molding method, or a doctor blade molding method, the pressure at the time of molding or The flow causes the scaly boron nitride in the resin or the rubber to collapse in the sheet, that is, the long diameter direction of the scaly boron nitride tends to match the direction of the sheet surface. Therefore, the insulating heat-dissipating sheet obtained in this manner is excellent in thermal conductivity in the sheet surface direction. However, in the use form in which the sheet thickness direction is a heat conduction path, there is a problem in that excellent thermal conductivity cannot be sufficiently exhibited.

Then, there have been proposed a method in which the longitudinal direction of the scaly boron nitride dispersed in the resin or the rubber is aligned with the thickness direction of the sheet, that is, a method of aligning the thickness direction of the sheet in an upright state.

For example, in the Japanese Patent Publication No. 6-38460, a sheet in which the long diameter direction of the scaly boron nitride is aligned with the direction of the sheet surface is sliced in the thickness direction, thereby obtaining scaly nitridation. A heat dissipating sheet in which the long diameter direction of boron is aligned in the thickness direction.

In the patent document 2 (Japanese Patent No. 3,684,401), a sheet in which the major axis direction of the scaly boron nitride is aligned with the direction of the sheet surface is wound into a laminate, and the laminate is vertically cut. A heat dissipating sheet in which the long-diameter direction of the scaly boron nitride is aligned in the thickness direction.

In the patent document 3 (JP-A-2002-80617), a magnetic field is applied in the thickness direction of the sheet before the polymer composition containing scaly boron nitride is cured, thereby obtaining a long scaly boron nitride. A heat radiating sheet in which the magnetic field is aligned in the radial direction in parallel with the thickness direction of the sheet.

In Patent Document 4 (Japanese Patent Publication No. 6-12643), before the composition containing the organopolyoxane and the scaly boron nitride is cured, it is oscillated by an ultrasonic oscillator to obtain scaly nitridation. A heat dissipating sheet in which the long diameter direction of boron is not aligned in the direction of the sheet surface.

In the patent document 5 (JP-A-2003-60134), a heat-dissipating sheet containing 1 to 20% by mass of boron nitride secondary aggregated particles having a particle diameter of 50 μm or more is proposed. Further, it is described that the agglutination form of the secondary aggregated particles is not particularly limited, and for example, it is a natural agglutination due to van der Waals force, electrostatic force, moisture adsorption, or the like, or aggregation using an inorganic salt or a polymer substance. The agent is intentionally agglomerated by an operation such as mixing granulation, extrusion granulation, spray drying, or the like, and may be a form in which impurities such as B ₂ O ₃ generated in the production step are fixed to the grain boundary and aggregated.

In the patent document 6 (International Publication No. 2009/041300), a heat dissipating sheet containing 20% by volume or more of boron nitride secondary aggregate particles having a particle diameter of 50 μm or more has been proposed. In addition, in the secondary aggregate particles, primary particles of scaly boron nitride having an average major axis of 15 μm or less are uniformly aggregated and fired to form a spherical shape. Further, it is described that secondary aggregate particles can be obtained by agglomerating primary particles of scaly boron nitride by a known method such as a spray drying method, followed by firing and grain growth, and the firing temperature is not particularly limited. And generally about 2,000 ° C. Further, the peak intensity ratio I ₀₀₂ /I ₁₀₀ obtained by irradiating X-rays in the thickness direction of the sheet is 6 or more and 20 or less.

In Patent Document 7 (Japanese Patent No. 3461651), a mixture of boron nitride and melamine borate is fired at 1,700 to 2,200 ° C in a non-oxidizing gas atmosphere to obtain a boron nitride powder. Further, although it is not a sheet, the peak intensity ratio I ₀₀₂ /I ₁₀₀ obtained by irradiating X-rays to the boron nitride powder is 6 to 20.

In Patent Document 8 (Japanese Patent No. 4070345), boron nitride is surface-modified with an amine group-containing and mercapto group-containing decane coupling agent to obtain a heat-dissipating sheet. It is described that the heat dissipating sheet is intended to prevent moisture absorption and conduction in a high humidity state, and the decane solution and the boron nitride can be uniformly mixed using a general-purpose device such as a planetary mixer, a frame mixer, or a Shinagawa mixer, and then It is obtained by drying. Further, it is described that the amount of treatment is 0.1 to 5 parts by mass based on 100 parts by mass of boron nitride.

However, any of the methods of Japanese Patent Literatures 1 to 4 requires special equipment or complicated manufacturing steps, and thus is disadvantageous in terms of productivity or cost.

On the other hand, in the method of Japanese Patent Laid-Open No. 5, when the average long diameter of the primary particles of the scaly boron nitride constituting the secondary aggregated particles is large, the primary particles are aggregated in the same direction, and the heat-dissipating sheet is produced. In the step, when mixing, rolling, or the like is performed, the secondary aggregated particles are liable to collapse. Therefore, even if such secondary aggregated particles are aligned, the thermal conductivity in the thickness direction of the sheet cannot be sufficiently improved. Further, in the heat-dissipating sheet of Japanese Patent Laid-Open Publication No. 5, the secondary aggregated particles having a particle diameter of 50 μm or more are contained in an amount of only 1 to 20% by mass, and thus the thermal conductivity is insufficient.

In addition, in the method of the Japanese Patent Publication No. 6 to 7, the firing is performed at about 2,000 ° C so that I ₀₀₂ /I _{100 is} 6 or more and 20 or less, and the method of Japanese Patent Laid-Open No. 6 is not only in the form of scales. In the case of primary particles of boron nitride, it is necessary to have a high temperature of about 2,000 ° C in the production of secondary aggregated particles, which is disadvantageous in terms of cost. In Patent Document 7, when boron nitride is produced, it takes more time than the method for producing primary particles of scaly boron nitride, which is disadvantageous in terms of cost.

In the method of Patent Document 8, boron nitride is surface-modified by using an amine group-containing and sulfhydryl-based decane coupling agent, and in this method, only the surface of the primary particles of the scaly boron nitride is modified to cause scales. The long diameter direction of the boron nitride is aligned in the direction of the sheet surface.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 6-38460

[Patent Document 2] Japanese Patent No. 3564401

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2002-80617

[Patent Document 4] Japanese Patent Publication No. 6-12643

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2003-60134

[Patent Document 6] International Publication No. 2009/041300

[Patent Document 7] Japanese Patent No. 3461651

[Patent Document 8] Japanese Patent No. 4070345

The present invention has been made to solve the above problems, and an object thereof is to provide an insulating heat dissipating sheet and a granulation method for boron nitride used therefor, which is advantageous in productivity or cost, and thermal conductivity and electrical insulation. Excellent sex.

The present inventors have completed the present invention in order to achieve the above object, and have completed the present invention, and provided an insulating heat-dissipating sheet, a granulation method of boron nitride, and boron nitride.

[1] A method for granulating boron nitride, characterized in that boron nitride is sprayed in a fluidized layer, and a decane coupling agent having an amine group is sprayed and granulated.

[2] The granulation method of boron nitride according to [1], wherein the decane coupling agent having an amine group is sprayed in an amount of more than 5% by mass and not more than 30% by mass based on the mass of the boron nitride. .

[3] The granulation method of boron nitride according to [1] or [2], wherein the gas temperature of the gas supply to the fluidized bed is set to 50 ° C or more and less than 110 ° C.

[4] An insulating heat-dissipating sheet which causes a decane coupling agent having an amine group to have a mass of more than 5% by mass and 30% by mass relative to the mass of boron nitride by flowing boron nitride in the fluidized layer. the following amount of granulation, the resulting boron nitride dispersed in the rubber or the resin obtained by heat insulating sheet, characterized in the sheet thickness direction of the resulting X-ray irradiation in the X-ray diffraction pattern of the I-ray intensity of about 002 ₀₀₂ The peak intensity ratio I ₀₀₂ /I ₁₀₀ to the ratio of the intensity I ₁₀₀ of the 100-ray ray is 6 or more and 80 or less.

[5] An insulating heat-dissipating sheet obtained by dispersing boron nitride obtained by granulating a decane coupling agent having an organic group-containing organic group in an insulating heat-dissipating sheet composed of a polyoxyethylene rubber composition, characterized in that The peak intensity ratio I ₀₀₂ /I ₁₀₀ of the ratio of the intensity I _{002 of the 002} -ray ray and the intensity I ₁₀₀ of the ray around the X-ray diffraction pattern in the X-ray diffraction pattern to the thickness direction of the sheet is greater than 20 and 80 or less.

[6] A boron nitride powder characterized in that a decane coupling agent having an amine group is more than 5% by mass and 30 mass with respect to the mass of boron nitride while flowing boron nitride in the fluidized layer. The amount of the lower side is less than 5% by weight, and the peak intensity ratio I ₀₀₂ /I ₁₀₀ of the ratio of the intensity I ₀₀₂ of the 002-ray ray to the intensity of the 100-ray ray I _{100 in} the X-ray diffraction pattern obtained by the X-ray diffraction is 3 or more and 40 or less.

According to the present invention, it is possible to provide a heat dissipating sheet which is advantageous in productivity or cost, and which is excellent in thermal conductivity and electrical insulation.

Hereinafter, the insulating heat-dissipating sheet and boron nitride of the present invention and the granulation method thereof will be described in detail, and the present invention is not limited thereto.

In order to achieve the above-mentioned problem, the inventors of the present invention have found that it is an insulating heat-dissipating sheet obtained by dispersing boron nitride which has been subjected to granulation treatment with an amine-based decane coupling agent to a polyoxyethylene rubber composition. The scaly boron nitride dispersed in the rubber is in an upright state in the sheet, that is, the long diameter direction of the scaly boron nitride is increased in the direction in which the thickness direction of the sheet is aligned, thereby increasing the thickness direction of the sheet. The present invention has been completed by the thermal conduction of the improved insulating fins.

In this case, the granulation treatment is carried out by using boron nitride in the fluidized layer while the decane coupling agent having an amine group is more than 5% by mass and 30% by mass based on the mass of the boron nitride. The boron nitride obtained by the granulation by spraying is dispersed in various rubbers or resins, for example, polyfluorene rubber or resin, acrylic resin, etc., and X-ray diffraction is performed by irradiating X-rays in the thickness direction of the sheet. In the figure, the peak intensity ratio I ₀₀₂ /I ₁₀₀ of the ratio of the intensity I _{002 of the 002} around the ray to the intensity I ₁₀₀ of the ray is 6 to 80, preferably 10 to 80, more preferably more than 20 and 80 or less, and insulation heat dissipation. The sheet can obtain good thermal conductivity, and particularly in the case of dispersion in the polyoxyxene rubber, I ₀₀₂ /I _{100 is} preferably greater than 20 and 80 or less from the viewpoint of a rapid increase in thermal conductivity.

Further, the boron nitride used in the present invention is preferably in the form of a scaly shape, and the size thereof is preferably a long diameter of 1 to 100 μm and a short diameter of 0.05 to 50 μm. As described later, it is suitable to carry out granulation treatment.

The degree of alignment of the scaly boron nitride in the heat dissipating sheet can be evaluated using an X-ray diffraction device. Specifically, the degree of alignment may be a peak intensity ratio I ₀₀₂ / of a ratio of the intensity I _{002 of the 002} -ray ray to the intensity I ₁₀₀ of the ray around the X-ray diffraction pattern in the X-ray diffraction pattern of the heat-dissipating sheet. I ₁₀₀ for evaluation. When the ratio of the long diameter direction of the scaly boron nitride to the direction parallel to the sheet surface direction is high, the intensity ratio I ₀₀₂ /I ₁₀₀ becomes large, and the long diameter direction of the scaly boron nitride is aligned in parallel with the thickness direction of the sheet. The case of a high ratio will become smaller.

The strength ratio I ₀₀₂ /I ₁₀₀ of the heat-dissipating sheet of the polyoxyethylene rubber of the present invention is preferably in the range of 6 to 80, particularly 20 or more and 80 or less, preferably 20 or more and 60 or less, as described above. When the intensity ratio is too small, the ratio of the long diameter direction of the scaly boron nitride to the parallel direction of the thickness direction of the sheet is high, and the dielectric breakdown property may be lowered. On the other hand, when the intensity ratio is more than 80, the ratio of the long diameter direction of the scaly boron nitride to the direction parallel to the sheet surface direction is high, and a desired heat conductivity improving effect may not be obtained in the thickness direction of the sheet.

The spray liquid used in the granulation treatment is preferably a decane coupling agent without hindering the dispersibility in the polyoxyethylene rubber composition. Further, a decane coupling agent having an amine group is preferred, and boron nitride obtained by granulation is less likely to collapse during mixing, rolling, or the like in the production step of the heat-dissipating sheet. As a result, in the heat-dissipating sheet obtained by blending the granulated boron nitride, the granulated boron nitride having uniform thermal conductivity does not collapse in the heat-radiating sheet manufacturing step, and is uniformly dispersed. The thermal conductivity in the thickness direction of the sheet is increased.

The decane coupling agent having an amine group may, for example, be N-2-(aminoethyl)-3-aminopropyltrimethoxydecane, N-2-(aminoethyl)-3-aminopropyltriethoxy. Decane, 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, and the like. These decane coupling agents can be used singly or in combination.

The organopolyoxane constituting the polyoxyxylene rubber composition as the base material of the heat-dissipating sheet made of the polyoxyethylene rubber of the present invention has an average composition formula represented by the following formula (1): R _a SiO _{(4- a)/2} (1)

In the above formula (1), R is the same or different substituted or unsubstituted one-valent hydrocarbon group, preferably a hydrocarbon having 1 to 8 carbon atoms, such as an alkyl group such as a methyl group, an ethyl group or a propyl group; a vinyl group, an allyl alkenyl group, a phenyl group, a tolyl group or the like, a cycloalkyl group such as a cyclohexyl group or a cyclopentyl group, or a group thereof a chloromethyl group, a chloroethyl group, a trifluoropropyl group, a cyanoethyl group or a cyanopropyl group in which a part or all of a hydrogen atom directly bonded to a carbon atom is substituted with a halogen atom or a cyano group. It is preferably a methyl group, a phenyl group, a trifluoropropyl group or a vinyl group, and a is a positive number of 1.85 to 2.10.

The organic polyoxyalkylene is preferably a linear molecular structure, but a part of the molecule may have a molecular chain structure. Further, the organopolyoxane is preferably blocked at the end of the molecular chain with a triorganomenyl group or a hydroxyl group. The triorganosylalkyl group can be exemplified by trimethylmethanyl group, dimethylvinyl formyl group, trivinyl formyl group, methylphenylvinyl formyl group, methyl benzoyl fluorenyl group, and dimethyl group. Phenyl phenyl decyl, dimethyl hydroxymethyl decyl, and the like.

The crosslinking agent can be appropriately selected in accordance with the mechanism of the crosslinking reaction of the organopolyoxane.

In the case where the crosslinking is a radical reaction, an organic peroxide is used, and specifically, benzammonium peroxide, perchlorinated monochlorobenzamide, peroxybis 2,4-dichlorobenzamide, O-Methyl benzamidine peroxide, p-methylbenzhydryl peroxide, di(t-butyl)peroxybenzoate, dicumyl peroxide, 2,5-dimethyl-2,5 - bis(t-butylperoxy)hexane, di-peroxide (t-butyl), and the like. The organic peroxide is preferably added in an amount of 0.1 to 10 parts by mass, particularly preferably 0.2 to 5 parts by mass, per 100 parts by mass of the organopolysiloxane.

Further, in the case where the crosslinking is an addition reaction, an organic hydroquinone having two or more hydrogen atoms directly bonded to a deuterium atom in one molecule, and an effective amount (catalytic amount) as a catalyst can be used. Platinum element (preferably white) Gold) or a compound thereof. In this case, the organopolyoxane must contain two or more alkenyl groups in one molecule. In the organohydrogen polyoxyalkylene, the hydrogen atom directly bonded to the ruthenium atom is preferably contained in an amount of 0.5 to 5 times, particularly 0.6 to 3 times, relative to the alkenyl group.

Further, in the case where the crosslinking is a condensation reaction, a hydrolyzable decane or a ruthenium containing two or more, preferably three or more, hydrolyzable groups such as an alkoxy group, an ethoxy group or a fluorenyl group in one molecule is used. The alkane acts as a crosslinking agent. The blending amount is 1 to 20 parts by mass, particularly 2 to 10 parts by mass, per 100 parts by mass of the organopolysiloxane. Further, the catalyst is preferably an organometallic compound using Sn, Ti, Fe, Co or the like. In this case, both ends of the molecular chain of the organopolyoxane must be blocked with a hydroxyl group or an alkoxy group. The blending amount of the crosslinking agent can be appropriately adjusted depending on the kind of the other components or the blending ratio.

The insulating heat-dissipating sheet made of the polyoxyethylene rubber of the present invention may be blended with a reinforcing reinforcing agent, a dispersing agent, a flame retardant, and a heat-resistant aid in addition to the components of the above-mentioned boron nitride or polyoxyethylene rubber composition. Agent, organic solvent for dilution, pigment for coloring, hardening inhibitor, and the like. Further, it may contain a glass fiber cloth which becomes a skeleton at the time of molding.

The insulating heat-dissipating sheet of the present invention can be uniformly mixed by a general-purpose apparatus using a planetary mixer, a frame mixer, a Shinagawa mixer, a Banbury mixer, a three-roller, a kneader, etc., by calendering and injection molding. A well-known molding method such as an extrusion molding method, a calender molding method, a roll molding method, or a doctor blade molding method is formed into a sheet shape and then cured. The insulating heat-dissipating sheet obtained in this manner can be arbitrarily provided with an adhesive or a protective paper or film.

The boron nitride treated with the amine group-containing decane coupling agent used in the insulating heat-dissipating sheet of the present invention is nitrided by spraying and granulating the decane coupling agent by using boron nitride in the fluidized bed. The granulation method of boron is advantageous in terms of productivity or cost.

The decane coupling agent is preferably more than 5% by mass and not more than 30% by mass, and preferably from 8 to 25% by mass, based on the mass of the boron nitride. When the mass ratio is 5% by mass or less, the ratio of the long diameter direction of the scaly boron nitride to the parallel direction of the sheet surface direction is high, and the desired heat conductivity improving effect may not be obtained in the thickness direction of the sheet. On the other hand, when the mass ratio is more than 30% by mass, a thick low heat conductive layer is formed around the boron nitride, and thus the heat conductivity improving effect may not be obtained.

In order to prepare a decane solution, it is generally used by dissolving a decane coupling agent in water, or by dissolving a decane coupling agent in a lower alcohol such as methanol or ethanol, and then adding water, and then adding an organometallic compound such as acetic acid, hydrochloric acid or Sn as necessary. A hydrolysis catalyst such as a method of stirring and performing ultrasonic vibration or the like. The amine group-containing group (hereinafter collectively referred to as amino decane) has a high hydrolysis rate and does not require a catalyst. After the amino decane is dissolved in water, ultrasonic vibration is performed to prepare a decane solution.

The temperature of the gas supplied to the fluidized bed is preferably 50 ° C or more and less than 110 ° C. When the temperature is less than 50 ° C, large granules are observed everywhere, and irregularities are formed on the surface of the heat-dissipating sheet after molding, and the contact thermal resistance may become large. On the other hand, when the temperature is 110 ° C or more, the uniform dispersibility in the polyoxymethylene rubber composition may be deteriorated.

Further, the spraying speed is preferably from 0.1 to 30 g/min, preferably from 0.2 to 20 g/min, more preferably from 0.3 to 4 g/min. If it is slower than 0.1 g/min, the granulation time becomes long, which is disadvantageous in terms of cost. If it is faster than 30 g/min, the particle size distribution of the granulated powder becomes broad and it is disadvantageous.

Further, in this manner resulting boron nitride powder, which emits X-rays in the resulting X-ray diffraction pattern ray intensity around 002 and 100 about the I _002-ray intensity ratio of the peak intensity ratio I ₁₀₀ I ₀₀₂ / I _{100 is} preferably 3 to 40, preferably 6 to 20.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the method of granulating the insulating heat-dissipating sheet and boron nitride of the present invention, and the present invention is not limited thereto.

[Example 1] [Modulation of decane solution]

After dissolving 50 g of N-2-(aminoethyl)-3-aminopropyltrimethoxydecane (KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) in 200 g of water, the mixture was stirred and subjected to ultrasonic vibration to prepare 250 g of decane solution.

[Pulverization treatment of boron nitride]

In a fluidized layer granulation drying coating apparatus (MP-01) manufactured by Powrex Co., Ltd., 500 g of scaly boron nitride was placed and disposed as a spray liquid. The above decane solution was 250 g. Therefore, the decane coupling agent was disposed in an amount of 10% by mass based on the mass of the boron nitride. The granulation treatment was carried out at a spray rate of 8 g/min and a supply temperature of 80 °C.

[Modulation of heat sink sheet composition]

100 parts by mass of an organic polyoxane having 99.85 mol% of a dimethyloxane unit, 0.15 mol% of a methylvinylaluminoxane unit and an average degree of polymerization of about 8,000, and boron nitride obtained by the above granulation treatment 400 parts by mass and 3 parts by mass of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane as a crosslinking agent were dispersed in 400 parts by mass of toluene, and mixed by a planetary mixer. A heat sink sheet composition is prepared.

[Forming of heat sink sheet]

The above heat-dissipating sheet composition was applied by a doctor blade to a thickness of 0.3 mm on a PET separator, and then dried at 80 ° C for 10 minutes to prepare two pieces. The dried heat-dissipating sheet composition was placed in contact with each surface of a glass fiber cloth having a thickness of 0.05 mm, and calendered and heat-cured at a temperature of 170 ° C and a pressure of 100 kg/cm ² for 10 minutes to obtain an insulating heat-dissipating sheet. Next, it was subjected to secondary vulcanization at 200 ° C for 4 hours under normal pressure. The thickness of the obtained heat radiating sheet was 0.3 mm.

[assessment]

For the alignment of the scaly boron nitride in the heat dissipating sheet, an X-ray diffraction device is used, and the CuKα line is used to scan 2θ, 20 to 60° at 30 kV, 30 mA, and the 002 is ray around 26.9°. The peak intensity ratio I ₀₀₂ /I _{100 was} obtained from the peak intensity and the peak intensity of the 100-ray ray around 41.6°.

The thermal resistance was measured using a TO-3 type transistor. The dielectric breakdown voltage was measured by the measurement method of JIS K6249. The results are shown in Table 1.

[Embodiment 2]

In addition to the preparation of the decane solution, 30 g of N-2-(aminoethyl)-3-aminopropyltrimethoxydecane (KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in 220 g of water, and then stirred. The heat-dissipating sheet was formed in the same manner as in Example 1 except that 250 g of a decane solution was prepared by the ultrasonic vibration, and the decane coupling agent was adjusted to have a mass of 6% by mass based on the mass of the boron nitride. to evaluate.

[Example 3]

In the preparation of a decane solution, 150 g of N-2-(aminoethyl)-3-aminopropyltrimethoxydecane (KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in 100 g of water, and then stirred. Ultrasonic vibration was carried out to prepare 250 g of a decane solution, and the heat-dissipating sheet was formed in the same manner as in Example 1 except that the decane coupling agent was adjusted to have a mass of 30% by mass based on the mass of the boron nitride. to evaluate.

[Example 4]

In addition to setting the supply temperature of the granulation treatment to 50 ° C, The heat dissipating sheet was shaped and evaluated in the same manner as in Example 1.

[Example 5]

The heat radiating sheet was molded and evaluated in the same manner as in Example 1 except that the supply temperature of the granulation treatment was set to 109 °C.

[Embodiment 6]

The heat dissipating sheet was molded and evaluated in the same manner as in Example 1 except that 3-aminopropyltrimethoxydecane (KBM-903, manufactured by Shin-Etsu Chemical Co., Ltd.) was used in the preparation of the decane solution.

[Embodiment 7]

The same procedure as in Example 1 except that N-2-(aminoethyl)-3-aminopropyltriethoxydecane (KBE-603, manufactured by Shin-Etsu Chemical Co., Ltd.) was used in the preparation of the decane solution. The way the heat sink sheet is shaped and evaluated.

[Embodiment 8]

The heat dissipating sheet was molded and evaluated in the same manner as in Example 1 except that 3-aminopropyltriethoxydecane (KBE-903, manufactured by Shin-Etsu Chemical Co., Ltd.) was used in the preparation of the decane solution.

[Comparative Example 1]

In addition to the granulation treatment of boron nitride during the modulation of decane treatment, The heat dissipating sheet was shaped and evaluated in the same manner as in the first embodiment.

[Examples 9 to 13] [Modulation of decane solution]

After dissolving 100 g of N-2-(aminoethyl)-3-aminopropyltrimethoxydecane (KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) in 200 g of water, the mixture was stirred and subjected to ultrasonic vibration to prepare 300 g of decane solution.

[Bonding treatment of boron nitride]

In a fluidized bed granulation and drying coating apparatus (MP-01) manufactured by Powrex Co., Ltd., 500 g of scaly boron nitride was placed, and 250 g of the above decane solution as a spray liquid was placed. Therefore, the decane coupling agent is configured to be nitrided relative to The mass of boron is 20% by mass. The granulation treatment was carried out at a spray rate of 0.3 to 40 g/min and a supply temperature of 70 °C.

[Modulation of heat sink sheet composition]

100 parts by mass of an organic polyoxane having 99.85 mol% of a dimethyloxane unit, 0.15 mol% of a methylvinylaluminoxane unit and an average degree of polymerization of about 8,000, and boron nitride obtained by the above granulation treatment 400 parts by mass and 3 parts by mass of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane as a crosslinking agent are dispersed in 400 parts by mass of toluene and mixed by a planetary mixer. A heat sink sheet composition is prepared.

[Forming of heat sink sheet]

The above heat-dissipating sheet composition was applied by a doctor blade to a thickness of 0.3 mm on a PET separator, and then dried at 80 ° C for 10 minutes to prepare two pieces. The dried heat-dissipating sheet composition was placed in contact with each surface of a glass fiber cloth having a thickness of 0.05 mm, and calendered and heat-cured at a temperature of 170 ° C and a pressure of 100 kg/cm ² for 10 minutes to obtain an insulating heat-dissipating sheet. Next, it was subjected to secondary vulcanization at 200 ° C for 4 hours under normal pressure. The thickness of the obtained heat radiating sheet was 0.3 mm.

[assessment]

Regarding the orientation of the boron nitride powder obtained by granulation, the powder is filled into a glass test cell, using an X-ray diffraction device, with a CuK α line and at 30 kV, 30 mA, 2 θ, scanning range 20 to 60 °, the peak intensity ratio I ₀₀₂ /I _{100 was} obtained from the peak intensity of the 002 ray around 26.9° and the peak intensity of the 100 ray around 41.6°.

The formed heat dissipation sheet was used to measure the thermal resistance and the dielectric breakdown voltage. The thermal resistance was measured using a TO-3 type transistor. The dielectric breakdown voltage was measured in accordance with the measurement method of JIS K6249. The results are shown in Table 2.

Claims (6)

A granulation method of boron nitride, characterized in that a boron hydride coupling agent having an amine group is dissolved in water or a decane solution obtained by dissolving in a lower alcohol and adding water while flowing boron nitride in a fluidized bed. It is granulated by spraying. The granulation method of boron nitride according to claim 1, wherein the decane coupling agent having an amine group is sprayed in an amount of more than 5% by mass and not more than 30% by mass based on the mass of the boron nitride. The granulation method of boron nitride according to claim 1 or 2, wherein the gas supply to the fluidized bed is set to a temperature of 50 ° C or more and less than 110 ° C. A method for producing an insulating heat dissipating sheet, comprising: flowing a boron nitride in a fluidized layer while dissolving a decane coupling agent having an amine group in water or dissolving in a lower alcohol and adding water to form a decane solution; a step of obtaining boron nitride by using granules having an amine group-containing decane coupling agent in an amount of more than 5% by mass and 30% by mass or less based on the mass of boron nitride, and dispersing the obtained boron nitride in rubber or A method for producing an insulating heat-dissipating sheet in the step of resin, characterized in that a peak intensity ratio of a ratio of an intensity I ₀₀₂ of a 002-ray ray and an intensity of a 100-ray ray to an intensity I ₁₀₀ in an X-ray diffraction pattern obtained by irradiating X-rays in a thickness direction of a sheet I ₀₀₂ /I ₁₀₀ is 6 or more and 80 or less. A method for producing an insulating heat-dissipating sheet, comprising: flowing a boron nitride in a fluidized layer while dissolving a decane coupling agent having an amine group in water or dissolving in a lower alcohol and adding water to form a decane solution; A method for producing an insulating heat-dissipating sheet obtained by a step of granulating a boron nitride and a step of dispersing the obtained boron nitride in a polyoxyxene rubber composition, characterized in that X-rays are obtained by irradiating X-rays in the thickness direction of the sheet. The peak intensity ratio I ₀₀₂ /I ₁₀₀ of the ratio of the intensity I _{002 of the 002} -ray ray to the intensity I ₁₀₀ of the ray in the shot is greater than 20 and 80 or less. A method for producing a boron nitride powder, comprising: a decane solution obtained by dissolving a decane coupling agent having an amine group in water or dissolving in a lower alcohol and adding water while flowing boron nitride in the fluidized bed; A method for producing a boron nitride powder by a step of performing spray granulation with an amount of the decane coupling agent having an amine group in an amount of more than 5% by mass and 30% by mass or less based on the mass of the boron nitride. The peak intensity ratio I ₀₀₂ /I ₁₀₀ of the ratio of the intensity I _{002 of the 002} -ray ray and the intensity I ₁₀₀ of the ray around the X-ray diffraction pattern in the X-ray diffraction pattern is 3 or more and 40 or less.