JP2012229317A - Transparent thermoconductive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent thermoconductive composition excellent in transparency and thermal conductivity, and capable of dealing with various applications.SOLUTION: This transparent thermoconductive composition includes a resin and a filler, where the filler comprises a thermoconductive filler having an average particle diameter of 1-100 μm and a coefficient of thermal conductivity of ≥2 W/m×K and a high refractive index filler having an average particle diameter of 1-100 nm and ≥1.8 refractive index. With such a transparent thermoconductive composition, various resins and fillers can be used according to purposes and applications, and excellent transparency and thermoconductivity can be secured. Thereby such a transparent thermoconductive composition can be used in various heat dissipation applications requiring transparency and thermoconductivity.

Description

  The present invention relates to a transparent heat conductive composition having transparency and heat conductivity.

  In recent years, power electronics technology that converts and controls electric power using a semiconductor element has been adopted in hybrid devices, high-brightness LED devices, electromagnetic induction heating devices, and the like. In the power electronics technology, in order to convert a large current into heat or the like, a material disposed in the vicinity of the semiconductor element is required to have high heat dissipation (high thermal conductivity).

  Further, in high-luminance LED devices and the like, it is required to dissipate heat not only from the non-light-emitting portion but also from the light-emitting portion.

  For example, a liquid silicone resin that is a transparent polymer composition and its curing agent are added with a refractive index adjusting agent silicone oil and a curing catalyst to form a matrix material, and in the matrix material, thermal conductivity A transparent heat conductive composition obtained by blending amorphous spherical silica as a filler has been proposed (see, for example, Patent Document 1).

JP 2010-248311 A

  However, the transparent thermal conductive composition described in the cited document 1 is excellent in transparency because the refractive index of the silicone resin is adjusted by the refractive index adjusting agent, but the resin whose refractive index can be adjusted by such a refractive index adjusting agent. In addition, since the heat conductive filler with a small difference between the resin and the refractive index is also limited, the selectivity of the resin and the heat conductive filler is poor, the diversity is inferior, and it cannot be used for various applications. There is a problem that.

  An object of the present invention is to provide a transparent heat conductive composition which is excellent in transparency and heat conductivity and can be used for various applications.

  In order to achieve the above object, the transparent thermal conductive composition of the present invention contains a resin and a filler, and the filler has an average particle diameter of 1 to 100 μm and a thermal conductivity of 2 W / m ·. It is characterized by containing a thermally conductive filler that is K or more and a high refractive index filler that has an average particle diameter of 1 to 100 nm and a refractive index of 1.8 or more.

  In addition, the transparent heat conductive composition of the present invention preferably has a haze value of more than 0% and 10% or less and a total light transmittance of 70% or more at a thickness of 100 μm.

  Moreover, in the transparent heat conductive composition of this invention, it is suitable that the content rate of the said heat conductive filler is 30-90 volume% with respect to the total amount of a transparent heat conductive composition.

  Moreover, in the transparent heat conductive composition of this invention, it is suitable that the content rate of the said high refractive index filler is 10 volume% or less with respect to the total amount of a transparent heat conductive composition.

  In the transparent heat conductive composition of the present invention, it is preferable that the high refractive index filler is at least one selected from the group consisting of titanium oxide, zirconium oxide, zinc oxide and barium titanate.

  Moreover, it is suitable for the transparent heat conductive composition of this invention to be used as a sealing material for sealing an optical semiconductor.

  According to the transparent heat conductive composition of the present invention, various resins and fillers can be used according to the purpose and application, and excellent transparency and heat conductivity can be ensured.

  Therefore, the transparent heat conductive composition of this invention can be used for the various heat dissipation use as which transparency and heat conductivity are requested | required.

  The transparent heat conductive composition of the present invention contains a resin and a filler.

  The resin can disperse the filler, that is, a dispersion medium (matrix) in which the filler is dispersed, and examples thereof include a thermosetting resin and a thermoplastic resin.

  Examples of the thermosetting resin include epoxy resins, thermosetting polyimides, phenol resins, urea resins, melamine resins, unsaturated polyester resins, diallyl phthalate resins, silicone resins, thermosetting urethane resins, and the like.

  Examples of the thermoplastic resin include polyolefin (for example, polyethylene, polypropylene, ethylene-propylene copolymer), acrylic resin (for example, polymethyl methacrylate), polyvinyl acetate, ethylene-vinyl acetate copolymer, poly Vinyl chloride, polystyrene, polyacrylonitrile, polyamide (nylon (registered trademark)), polycarbonate, polyacetal, polyethylene terephthalate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyallylsulfone, thermoplastic polyimide, heat Plastic urethane resin, polyamino bismaleimide, polyamideimide, polyetherimide, bismaleimide triazine resin, polymethylpentene, fluoride tree , Liquid crystal polymers, olefin - vinyl alcohol copolymer, ionomer, polyarylate, acrylonitrile - ethylene - Styrene copolymer, acrylonitrile - butadiene - styrene copolymer, acrylonitrile - styrene copolymer.

  The resin contains, for example, a polymer precursor (for example, a low molecular weight polymer including an oligomer) and / or a monomer in addition to the above-described components (polymerized products).

  These resins can be used alone or in combination of two or more.

  Such a resin is preferably a thermosetting resin, more preferably an epoxy resin, a thermosetting polyimide resin, or a silicone resin.

  The epoxy resin is not particularly limited, and is a known epoxy resin, specifically, for example, bisphenol type epoxy resin, novolac type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, triphenylmethane type epoxy resin, etc. Aromatic epoxy resins, for example, nitrogen-containing ring epoxy resins such as triepoxypropyl isocyanurate and hydantoin epoxy resins, and aliphatic type epoxy resins (including aliphatic alicyclic epoxy resins), glycidyl ether type epoxies Examples thereof include resins and glycidylamine type epoxy resins.

  Epoxy resins include, for example, curing agents such as imidazole compounds, amine compounds, acid anhydride compounds, amide compounds, hydrazide compounds, imidazoline compounds, phenolic compounds, urea compounds, polysulfide compounds, and further, for example, triethylenediamine. And tertiary amine compounds such as tri-2,4,6-dimethylaminomethylphenol, such as triphenylphosphine, tetraphenylphosphonium tetraphenylborate, tetra-n-butylphosphonium-o, o-diethylphosphorodithioate It is possible to prepare an epoxy resin composition by containing a curing accelerator such as a phosphorus compound such as a quaternary ammonium salt compound such as an organometallic salt compound such as a derivative thereof. In addition, the mixture ratio of a hardening | curing agent and a hardening accelerator is not restrict | limited in particular, According to the objective and a use, it sets suitably.

  Further, the curing agent and / or the curing accelerator can be prepared as a solvent solution and / or a solvent dispersion dissolved and / or dispersed with a solvent, if necessary.

  Examples of the solvent include organic solvents such as ketones such as acetone and methyl ethyl ketone (2-butanone), esters such as ethyl acetate, and amides such as N, N-dimethylformamide (DMF), and the like. . Examples of the solvent include water-based solvents such as water, for example, alcohols such as methanol, ethanol, propanol, isopropanol (2-propanol), and methoxyethanol. The solvent is preferably an organic solvent, more preferably ketones and amides.

  The thermosetting polyimide resin can be obtained, for example, by imidizing a polyamic acid resin by heating.

  The polyamic acid resin is not particularly limited. For example, an acid dianhydride (for example, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA)) and a diamine (for example, bis [4 It can be obtained by reacting with-(3-aminophenoxy) phenyl] sulfone (3-BAPS) and the like.

  In this reaction, the acid dianhydride and the diamine are reacted at a ratio that provides a substantially equimolar ratio.

  In addition, acid dianhydride and diamine are mixed with an appropriate organic solvent, for example, an organic solvent such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, at normal temperature and pressure. The polyamic acid resin solution can be obtained by reacting under a predetermined time.

  In addition, you may mix | blend an epoxy resin, a bisallyl nadic imide, a maleimide, etc. with the polyamic acid resin obtained in this way as needed.

  Examples of the silicone resin include known silicone resins, specifically, methyl silicone alkoxy oligomers, methyl phenyl silicone alkoxy oligomers, organic functional group (excluding alkoxy groups) -containing oligomers, and the like.

  In such a silicone resin, examples of the alkoxy group include a methoxy group and an ethoxy group. Moreover, as an organic functional group (except an alkoxy group), an epoxy group, an acryl group, a methacryl group, an amino group etc. are mentioned, for example.

  When the silicone resin has a plurality of alkoxy groups and / or organic functional groups (excluding alkoxy groups), they may be the same or different from each other.

  Further, the content ratio of these alkoxy groups and / or organic functional groups is appropriately set according to the purpose and application.

  In addition, as resin, it is not limited to above-described resin, Various resin can be used.

  In addition, such a resin is usually in a liquid, semi-solid state or solid state at 23 ° C., but the shape of the resin used is not particularly limited, depending on the purpose and application, It is selected appropriately.

  The refractive index of the resin is, for example, 1.4 to 2.0, preferably 1.4 to 1.8.

  The filler contains a thermally conductive filler and a high refractive index filler.

  The thermally conductive filler is, for example, a spherical, plate-like (scale-like) filler having an average particle diameter of 1 to 100 μm and a thermal conductivity of 2 W / m · K or more.

  Specifically, the average particle diameter (the maximum length in the case of plate-like particles) measured by the light scattering method of the heat conductive filler is 1 to 100 μm, preferably 10 to 180 μm, as described above. More preferably, it is 20-100 micrometers.

  Further, as described above, the thermal conductivity of the thermally conductive filler is 2 W / m · K or more, preferably 3 W / m · K or more, more preferably 5 W / m · K or more.

  Moreover, the refractive index of a heat conductive filler is 1.4-2.0, for example, Preferably, it is 1.4-1.8.

  Examples of such a thermally conductive filler include inorganic particles, and examples of the inorganic particles include carbides, nitrides, oxides, hydroxides, metals, and carbon-based materials.

  Examples of the carbide include silicon carbide, boron carbide, aluminum carbide, titanium carbide, and tungsten carbide.

  Examples of the nitride include silicon nitride, boron nitride, aluminum nitride, gallium nitride, chromium nitride, tungsten nitride, magnesium nitride, molybdenum nitride, and lithium nitride.

  Examples of the oxide include iron oxide, silicon oxide (silica), aluminum oxide (alumina), magnesium oxide (magnesia), titanium oxide, cerium oxide, and zirconium oxide. Examples of the oxide include transition metal oxides such as barium titanate, and further doped with metal ions such as indium tin oxide and antimony tin oxide.

  Examples of the hydroxide include aluminum hydroxide, calcium hydroxide, and magnesium hydroxide.

  Examples of the metal include copper, gold, nickel, tin, iron, and alloys thereof.

  Examples of the carbon-based material include carbon black, graphite, diamond, fullerene, carbon nanotube, carbon nanofiber, nanohorn, carbon microcoil, and nanocoil.

  In addition, the inorganic particles may be surface-treated by a known method with a silane coupling agent, if necessary, from the viewpoint of fluidity.

  These thermally conductive fillers can be used alone or in combination of two or more.

  Moreover, a heat conductive filler can also be prepared as a dispersion liquid of an above-described solvent as needed.

  In such a case, the solid content concentration of the thermally conductive filler is appropriately set according to the purpose and application.

  The high refractive index filler is, for example, a spherical filler having an average particle diameter of 1 to 100 nm and a refractive index of 1.8 or more.

  Specifically, the average particle diameter measured by the light scattering method of the high refractive index filler is 1 to 100 nm, preferably 1 to 80 nm, and more preferably 1 to 50 nm as described above.

  Further, as described above, the refractive index of the high refractive index filler is 1.8 or more, preferably 1.85 or more, and usually 2.7 or less.

  Examples of such a high refractive index filler include the inorganic particles described above.

  These high refractive index fillers can be used alone or in combination of two or more.

  Preferred examples of the high refractive index filler include titanium oxide, zirconium oxide, zinc oxide, and barium titanate.

  Moreover, the high refractive index filler can also be prepared as a dispersion liquid of the above-described solvent, if necessary.

  In such a case, the solid content concentration of the high refractive index filler is appropriately set according to the purpose and application.

  Moreover, in the transparent heat conductive composition, the refractive index of resin is adjusted with the high refractive index filler.

  The refractive index of the resin containing the high refractive index filler is, for example, 1.4 to 1.8, preferably 1.45 to 1.76, and the refractive index of the resin containing such a high refractive index filler and The absolute value of the difference from the refractive index of the thermally conductive filler is, for example, less than 0.05, preferably less than 0.03, more preferably less than 0.01, and particularly preferably 0.

  If the absolute value of the difference between the refractive index of the resin containing the high refractive index filler and the refractive index of the thermally conductive filler is in the above range, excellent transparency of the transparent thermally conductive composition can be ensured.

  And a transparent heat conductive composition is prepared by stirring and mixing each above-described component by a well-known method in the above-mentioned ratio.

  In the stirring and mixing, in order to mix each component efficiently, for example, a solvent can be blended with each component described above, or the resin can be melted by heating, for example.

  Examples of the solvent include the same organic solvents as described above. Further, when the above-mentioned resin, curing agent and / or curing accelerator, and filler are prepared as a solvent solution and / or a solvent dispersion, the solvent can be used without adding a solvent in the stirring and mixing. The solvent of the solution and / or the solvent dispersion can be used as it is as a mixed solvent for stirring and mixing. Alternatively, a solvent can be further added as a mixed solvent in the stirring and mixing.

  In mixing and stirring, a known dispersant can be blended as necessary.

  In addition, when a dispersing agent is mix | blended, the mixing | blending ratio is suitably set according to the objective and a use.

  Moreover, when stirring and mixing using a solvent, the solvent is removed as necessary after stirring and mixing.

  To remove the solvent, for example, it is allowed to stand at room temperature for 1 to 48 hours, for example, heated at 40 to 100 ° C. for 0.5 to 3 hours, or reduced pressure of 0.001 to 50 kPa, for example. Heat at 20-60 ° C. for 0.5-3 hours under atmosphere.

  When melting resin by heating, heating temperature is 40-150 degreeC, for example, Preferably, it is 70-140 degreeC.

  In the transparent heat conductive composition, the blending ratio of the filler (the total amount of the heat conductive filler and the high refractive index filler) is, for example, 10 to 90 mass with respect to the total amount (solid content) of the transparent heat conductive composition. %, Preferably 20 to 80% by mass, and the blending ratio of the resin is, for example, 10 to 90% by mass, preferably 20 to 80%, based on the total amount (solid content) of the transparent heat conductive composition. % By mass. Moreover, the mixture ratio of a filler is 50-300 mass parts with respect to 100 mass parts of resin, Preferably, it is also 100-300 mass parts.

  Moreover, the compounding ratio of a heat conductive filler is 10-70 mass% with respect to the total amount (solid content total amount) of a transparent heat conductive composition on a mass basis, Preferably, it is 30-60 mass%. For example, it is 10-90 volume% with respect to the total amount (solid content total amount) of a transparent heat conductive composition by volume reference, Preferably, it is 30-90 volume%.

  According to such a transparent heat conductive composition, more excellent heat conductivity can be ensured.

  The blending ratio of the high refractive index filler is, for example, 60% by mass or less, preferably 50% by mass or less, and usually 5% by mass with respect to the total amount (solid content) of the transparent heat conductive composition. For example, 15% by volume or less, preferably 12% by volume or less, more preferably 10% by volume or less with respect to the total amount (solid content) of the transparent heat conductive composition on a volume basis. It is.

  According to such a transparent heat conductive composition, more excellent transparency can be ensured.

  The thermal conductivity of the transparent heat conductive composition is, for example, 0.2 W / m · K or more, preferably 0.3 W / m · K or more, more preferably 0.5 W / m · K or more, More preferably, it is 0.6 W / m · K or more, usually 10 W / m · K or less.

  In addition, the heat conductivity of a transparent heat conductive composition is measured by the pulse heating method. In the pulse heating method, a xenon flash analyzer “LFA-447 type” (manufactured by NETZSCH) is used.

  When the transparent heat conductive composition is formed into a sheet having a thickness of 100 μm by the method described later, the haze value is, for example, more than 0% and not more than 15%, preferably more than 0% and more than 10%. Hereinafter, more preferably, it exceeds 0% and is 7% or less.

  The haze value is a ratio of the scattered light to the transmitted light when the transmitted light (parallel light) incident from the light source is scattered through the sheet-like transparent heat conductive composition, and is represented by the following formula (1). Indicated by

Haze value (%) = (scattered light amount) / (total transmitted light amount) × 100 (1)
When the haze value is within the above range, a transparent heat conductive composition having more excellent transparency can be obtained. On the other hand, when the haze value exceeds the above range, the scattered light may increase and appear cloudy.

  The haze value is measured by a haze meter (“NDH2000” manufactured by Nippon Denshoku Industries Co., Ltd. or “HM-150 type” manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K7136 (2000).

  Further, when the transparent heat conductive composition is formed into a sheet having a thickness of 100 μm, the total light transmittance thereof is, for example, 60% or more, preferably 70% or more, more preferably 75% or more. .

The total light transmittance is the ratio of the transmitted light to the incident light when the light incident from the light source (incident light) is transmitted through the sheet-like transparent heat conductive composition, and is represented by the following formula (2). It is.
Total light transmittance (%) = (transmitted light amount) / (incident light amount) × 100 (2)
When the total light transmittance is less than the above range, the optical characteristics may be deteriorated.

  In addition, total light transmittance is based on JIS K7361-1 (1997) by a haze meter (Nippon Denshoku Industries Co., Ltd., "NDH2000" or "HM-150 type" of Murakami Color Research Laboratory Co., Ltd.). Measured.

  If the haze value and the total light transmittance are within the above ranges, more excellent transparency can be ensured.

  Next, a method for forming the transparent heat conductive composition into a sheet will be described.

  When the transparent heat conductive composition is formed into a sheet, for example, after applying the transparent heat conductive composition obtained by stirring and mixing the components by the above-described method to a substrate, if necessary, Hot press.

  Specifically, for example, if necessary, the transparent heat conductive composition is hot-pressed through two release films to obtain a press sheet.

  The conditions of the hot press are that the temperature is, for example, 50 to 150 ° C., preferably 60 to 140 ° C., the pressure is, for example, 1 to 100 MPa, preferably 5 to 50 MPa, and the time is, for example, 0 .1 to 100 minutes, preferably 1 to 10 minutes.

  Further, if necessary, the transparent heat conductive composition can be vacuum hot pressed. The degree of vacuum in the vacuum hot press is, for example, 1 to 100 Pa, preferably 5 to 50 Pa, and the temperature, pressure, and time are the same as those in the above-described hot press.

  Moreover, in this method, for example, a transparent heat conductive composition is applied to each of two release films, and the two transparent heat conductive compositions are overlapped via two release films, The transparent heat conductive composition can also be hot pressed.

  Further, when the resin is a thermosetting resin, for example, after the hot pressing process, an uncured (or semi-cured (B stage state)) sheet is thermally cured to produce a cured sheet. Can do.

  The above-described hot press or dryer is used to thermally cure the sheet made of the transparent heat conductive composition. Preferably, a dryer is used. The thermosetting conditions are such that the temperature is, for example, 60 to 250 ° C., preferably 80 to 200 ° C., and the pressure is, for example, 100 MPa or less, preferably 50 MPa or less.

  Thus, the thickness of the sheet-like transparent heat conductive composition obtained is 50-1000 micrometers, for example, Preferably, it is 100-800 micrometers.

  And according to the transparent heat conductive composition of this invention, while ensuring heat conductivity with a heat conductive filler, since the refractive index of resin can be adjusted with a high refractive index filler, according to the objective and a use. Various resins and fillers can be used, and excellent transparency and thermal conductivity can be ensured.

  Therefore, the transparent heat conductive composition of this invention can be used for the various heat dissipation use as which transparency and heat conductivity are requested | required. Specifically, it can be suitably used as a sealing material for a light emitting device, particularly as a sealing material for sealing an optical semiconductor (for example, a light emitting diode such as a near ultraviolet light emitting diode or a blue light emitting diode). .

  When using a transparent heat conductive composition as a sealing material for sealing an optical semiconductor, for example, a transparent heat conductive composition is an uncured (or semi-cured (B stage state)) sheet. It is formed.

  Then, for example, one or a plurality of optical semiconductors (such as light emitting diodes) are installed on a circuit board to which electric power is supplied from the outside, and the optical semiconductor and the circuit board are electrically joined by a wire or the like. In addition, a known housing is provided on the circuit board so as to surround the optical semiconductor, and an uncured (or semi-cured (B stage state)) sheet-like transparent heat conductive composition is provided in the housing. Fill.

  At this time, the transparent thermally conductive composition is deformed by pressing, and thereby adheres to the optical semiconductor and the wire.

  In this way, the optical semiconductor can be sealed with the transparent thermally conductive composition.

  In addition, a phosphor plate, a lens, etc. are arrange | positioned as needed on a transparent heat conductive composition and a housing.

  And since such a transparent heat conductive composition is equipped with the outstanding transparency and heat conductivity, it does not block the light which arises from an optical semiconductor, and seals an optical semiconductor with the outstanding heat dissipation efficiency. Can do.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples.

Example 1
In a container equipped with a stirrer, a reflux condenser, and a nitrogen introduction tube, an aqueous dispersion of a zirconium oxide (refractive index: 1.86) having an average particle diameter of 7 nm as a high refractive index filler (trade name: NZD-3005, solid content concentration: 30 mass % Sumitomo Osaka Cement) 5.0 g, 5.0 g of methanol, 5.0 g of 2-propanol, and 1 drop of concentrated hydrochloric acid were added to adjust the pH to about 2. Next, as a surface treatment agent, a solution prepared by dissolving 0.15 g of 3-glycidoxypropyltrimethoxysilane (silane coupling agent, trade name KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) in 1 g of 2-propanol was added from the dropping funnel over 10 minutes. The solution was added dropwise and stirred with heating at 60 ° C. for 1 hour. After completion of the reaction, the reaction solution was cooled to room temperature and substituted with 2-butanone to obtain a surface-treated zirconium oxide nanoparticle dispersion (solid content concentration: 30% by mass).

  Then, 2 g of an aliphatic alicyclic epoxy resin (trade name Celoxide 2021P, epoxy equivalent: 128 to 140 g / eqiv. Manufactured by Daicel Chemical Industries) and an acid anhydride compound (curing agent: trade name Ricacid MH-700) were added to the obtained dispersion. 1.5 g of hexahydrophthalic anhydride / 4-methyl-hexahydrophthalic anhydride (manufactured by Shin Nippon Rika) was dissolved.

  Furthermore, 5 g of aluminum hydroxide (trade name H-10, thermal conductivity 5 W / m · K, refractive index 1.57, average particle diameter of about 50 μm, manufactured by Showa Denko) is added as a thermally conductive filler, and heat conductivity is obtained using a homogenizer. The filler was dispersed.

  Next, the obtained dispersion was applied to a polyethylene terephthalate base material subjected to silicone release treatment so that the film thickness after drying was 75 μm, and dried at 60 ° C. for 5 minutes.

  Thereafter, two obtained films were stacked and hot-pressed with a spacer so that the film thickness became 100 μm by a press machine heated to 100 ° C. Thereafter, the temperature was raised to 150 ° C. while being pressurized and held for 10 minutes to complete the curing reaction, whereby the transparent heat conductive composition was formed into a sheet.

  The content of the high refractive index filler (zirconium oxide) was 6% by volume and the content of the heat conductive filler (aluminum hydroxide) was 40% by volume with respect to the total amount of the transparent heat conductive composition. It was.

  And the heat conductivity of the sheet | seat of the obtained transparent heat conductive composition was 1.1 W / m * K.

  The haze value was 3.2% and the total light transmittance was 83%.

  The refractive index of the resin containing the high refractive index filler was measured to be 1.57. On the other hand, the refractive index of the resin not containing the high refractive index filler was 1.51. The refractive index of the thermally conductive filler was 1.57, and the absolute value of the difference from the refractive index of the resin containing the high refractive index filler was 0.

Example 2
As a high refractive index filler, 20 g of titanium oxide powder (refractive index 2.4 manufactured by Rutile Ishihara Sangyo) and 2 g of a dispersant (trade name Disperbyk-111 manufactured by Big Chemie) were added to 50 g of N, N-dimethylacetamide. . Next, the total amount and 50 g of zirconia beads having a diameter of 0.1 mm were placed in a glass bottle and dispersed for 2 hours with a paint shaker to obtain a dispersion of titanium oxide having an average particle diameter of 65 nm.

  A polyamic acid resin solution (bis [4- (3-aminophenoxy) phenyl] sulfone / 3,3 ′, 4 prepared in advance so as to have a solid content concentration of 35% by mass was added to 4 g of the above-described titanium oxide dispersion. , 4′-biphenyltetracarboxylic dianhydride) was added to 7.2 g with stirring to obtain a resin solution having a titanium oxide concentration of 10% by volume based on the resin.

  Next, 10 g of boron nitride (trade name PT-110, thermal conductivity: 60 W / m · K, refractive index: 1.74, average particle size: 50 μm, manufactured by Momentive Performance Materials) as a thermally conductive filler is added to the above dispersion and mixed. Using a device (TK Hibismix 2P-03 Primex), the mixture was dispersed and dispersed at 30 rpm for 30 minutes while reducing the pressure to 0.6 mmHg to prepare a dispersion (transparent thermal conductive composition). .

  Next, the obtained dispersion is applied to a glass plate so that the film thickness after drying is 100 μm, and is treated at 10 ° C. for 1 hour, 150 ° C. for 1 hour, and 250 ° C. for 1 hour to imidize. At the same time, the transparent heat conductive composition was formed into a sheet.

  The content of the high refractive index filler (titanium oxide) was 3% by volume and the content of the heat conductive filler (boron nitride) was 36% by volume with respect to the total amount of the transparent heat conductive composition. .

  And the heat conductivity of the sheet | seat of the obtained transparent heat conductive composition was 7.2 W / m * K.

  The haze value was 5.9% and the total light transmittance was 78%.

  The refractive index of the resin containing the high refractive index filler was measured to be 1.74, while the refractive index of the resin not containing the high refractive index filler was 1.71. Moreover, the refractive index of the heat conductive filler was 1.74, and the absolute value of the difference from the refractive index of the resin containing the high refractive index filler was 0.

Example 3
In a container equipped with a stirrer, a reflux condenser, and a nitrogen introduction tube, an aqueous dispersion of a zirconium oxide (refractive index: 1.86) having an average particle diameter of 7 nm as a high refractive index filler (trade name: NZD-3005, solid content concentration: 30 mass % Sumitomo Osaka Cement) 10.0 g, 2-propanol 10.0 g, methoxyethanol 2 g, and 1 drop of concentrated nitric acid were added to adjust the pH to about 2.

  Next, as a silicone resin raw material, 4 g of a methyl silicone alkoxy oligomer (trade name X-40-9225, medium molecular weight type, Shin-Etsu Chemical) and a methyl silicone alkoxy oligomer (trade name X-40-9246, high molecular weight type, Shin-Etsu Chemical) 2 g was added dropwise at 70 ° C. over 2 hours, and then the reaction temperature was raised to 100 ° C. and heated and stirred for 1 hour.

  Next, 5 g of crushed silica (trade name: SQ-H22, thermal conductivity: 2.5 W / m · K, refractive index: 1.45, average particle size: about 22 μm Hayashi Kasei) is added as a thermally conductive filler, stirred, and cooled to room temperature. The low boiling point components were removed under reduced pressure.

  Thereafter, the obtained dispersion was applied to a polyethylene terephthalate base material subjected to silicone release treatment so that the film thickness after drying was 100 μm, and dried at 100 ° C. for 1 hour. Subsequently, the transparent heat conductive composition was shape | molded in the sheet form by heating at 150 degreeC for 5 hours, and making it harden | cure.

  The content of the high refractive index filler (zirconium oxide) was 9% by volume and the content of the heat conductive filler (crushed silica) was 31% by volume with respect to the total amount of the transparent heat conductive composition. .

  And the heat conductivity of the sheet | seat of the obtained transparent heat conductive composition was 0.6 W / m * K.

  The haze value was 1.8% and the total light transmittance was 89%.

  Further, the refractive index of the resin containing the high refractive index filler was measured and found to be 1.45, while the refractive index of the resin not containing the high refractive index filler was 1.41. The refractive index of the thermally conductive filler was 1.45, and the absolute value of the difference from the refractive index of the resin containing the high refractive index filler was 0.

Comparative Example 1
A transparent heat conductive composition was prepared in the same manner as in Example 1 except that the high refractive index filler was not blended, and the transparent heat conductive composition was molded into a 100 μm sheet.

  And the heat conductivity of the sheet | seat of the obtained transparent heat conductive composition was 1.2 W / m * K.

  The haze value was 12.4% and the total light transmittance was 58%.

Comparative Example 2
A transparent heat conductive composition was prepared in the same manner as in Example 2 except that the high refractive index filler was not blended, and the transparent heat conductive composition was formed into a sheet of 100 μm.

  And the heat conductivity of the sheet | seat of the obtained transparent heat conductive composition was 6.9 W / m * K.

  The haze value was 16.4% and the total light transmittance was 11%.

Comparative Example 3
A transparent heat conductive composition was prepared in the same manner as in Example 3 except that the high refractive index filler was not blended, and the transparent heat conductive composition was formed into a 100 μm sheet.

  And the heat conductivity of the sheet | seat of the obtained transparent heat conductive composition was 0.6 W / m * K.

  The haze value was 11.4% and the total light transmittance was 62%.

Example 4
A transparent heat conductive composition was prepared and molded into a sheet (semi-solid state (B stage)) in the same manner as in Example 1 except that the heat pressing was not performed for 10 minutes.

  Next, a blue light emitting diode (trade name: C460MB290 Cree) as an optical semiconductor was sealed with the above sheet by a conventional method.

  The brightness of the blue light emitting diode was measured using a luminance meter (MCPD-3000 Otsuka Electronics).

  The light extraction efficiency was determined by comparing the luminance of the transparent heat conductive composition before sealing with 100%, and the light extraction efficiency was 170% of that before sealing. there were.

  Moreover, when the temperature at the time of light emitting diode lighting was measured with the thermography (product made from FLIR SC660 FLIR) for evaluating the thermal radiation characteristic of a blue light emitting diode, the temperature around a chip | tip was 70 degreeC.

Comparative Example 4
The optical semiconductor was sealed in the same manner as in Example 4 except that a commercially available silicone elastomer (trade name KE-1052 manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the sealing material.

  Moreover, the brightness | luminance was measured using the luminance meter (MCPD-3000 Otsuka Electronics) as the brightness of a blue light emitting diode.

  The light extraction efficiency was determined by comparing the luminance of the transparent heat conductive composition before sealing with 100%, and the light extraction efficiency was 160% of that before sealing. there were.

  Further, when the temperature at the time of lighting of the light emitting diode was measured by thermography (manufactured by FLIR SC660 FLIR) for evaluating the heat radiation characteristic of the blue light emitting diode, the temperature around the chip was about 100 ° C.

Claims (6)

Containing resin and filler,
The filler has an average particle diameter of 1 to 100 μm, a thermal conductivity of 2 W / m · K or more, an average particle diameter of 1 to 100 nm, and a refractive index of 1.8 or more. A transparent heat conductive composition comprising a high refractive index filler. At a thickness of 100 μm
The haze value exceeds 0% and is 10% or less,
The transparent heat conductive composition according to claim 1, wherein the total light transmittance is 70% or more.   The content ratio of the said heat conductive filler is 30-90 volume% with respect to the total amount of a transparent heat conductive composition, The transparent heat conductive composition of Claim 1 or 2 characterized by the above-mentioned.   The content rate of the said high refractive index filler is 10 volume% or less with respect to the total amount of a transparent heat conductive composition, The transparent heat conduction as described in any one of Claims 1-3 characterized by the above-mentioned. Sex composition.   The high refractive index filler is at least one selected from the group consisting of titanium oxide, zirconium oxide, zinc oxide, and barium titanate, according to any one of claims 1 to 4. Transparent heat conductive composition.   It is used as a sealing material for sealing an optical semiconductor, The transparent heat conductive composition as described in any one of Claims 1-5 characterized by the above-mentioned.