JPWO2018139632A1 - Silicone hybrid polymer coated AlN filler - Google Patents

Abstract

A surface-coated AlN filler for providing a heat-resistant heat-dissipating material with little deterioration in properties such as thermal conductivity due to hydrolysis of the AlN filler surface, which can be used for a heat-dissipating member that requires high thermal conductivity, is obtained. The silicone-based hybrid polymer-coated AlN filler is a filler mainly composed of aluminum nitride whose surface is coated with a silicone-based hybrid polymer, and 5 g of the filler having an average particle size of 20 to 40 μm is added to 50 mL of ion-exchanged water. The electric conductivity of water after being held at a saturated water vapor pressure of 121 ° C. for 50 hours is 350 μS / cm or less.

Description

  The present invention relates to a filler mainly composed of aluminum nitride whose surface is coated with a silicone-based hybrid polymer (hereinafter referred to as “AlN filler”).

  Composite members (hereinafter referred to as “heat radiating members”) for the purpose of heat dissipation and heat dissipation due to their high heat conduction characteristics are widely used mainly in heavy electrical appliances and electrical products. This heat radiating member is composed of a composite material of a heat-resistant resin capable of imparting elasticity and a filler such as ceramic or metal having high thermal conductivity. In recent years, the required thermal conductivity has been increased due to higher density and integration of electronic components. Among them, there are many applications that require high electrical insulation. That is, both electrical insulation and high thermal conductivity are required. In general, those having high thermal conductivity have high electrical conductivity. Therefore, it is a contradictory required characteristic. For such a demand, ceramics such as alumina and zirconia are used, but the thermal conductivity is not a satisfactory value as compared with metal.

As ceramics having higher thermal conductivity than oxide ceramics, nitride ceramics such as aluminum nitride are used. AlN has a high insulating property and has a high thermal conductivity of 170 W · m ⁻¹ · K ⁻¹ , and thus has been widely used as a high thermal conductive insulating plate. Attempts have been made to produce functional materials having high thermal conductivity by using nitride ceramics such as AlN as fillers and blending them into various resins. AlN fillers can impart high thermal conductivity to resins that originally have low thermal conductivity. Therefore, AlN fillers can be combined with AlN fillers and resins to form heat-dissipating members and put into practical use for cooling heating elements in various fields. Has been.

However, it is known that the AlN filler used for such applications easily reacts with moisture in the atmosphere to cause hydrolysis and is decomposed into aluminum hydroxide and ammonia (AlN + 3H ₂ O → Al (OH)). ₃ + _{NH 3).} When AlN is hydrolyzed and becomes Al (OH) ₃ , the thermal conductivity is deteriorated, and high thermal conductivity cannot be imparted to the composite material. In particular, silicone resins and nylon resins used in heat conductive sheets where heat resistance is important have low gas barrier properties to block water vapor in the atmosphere, and AlN combined as a filler tends to be easily hydrolyzed. is there. Therefore, AlN is easily hydrolyzed in a resin having a low gas barrier property, and the thermal conductivity decreases with time.

  In addition, since most of the general-purpose resins perform filler mixing by melt kneading (biaxial kneading-extrusion molding) in the atmosphere and at a high temperature using solid pellets, exposure of the mixed filler to water vapor is not common. Therefore, it has been essential to stabilize the surface of the filler to be blended, particularly the AlN filler, by applying a surface treatment.

  Generally, as a water-resistant treatment agent for an AlN filler, various coupling agents such as a silane coupling agent and a phosphoric acid treatment agent are known.

  The various coupling agents provide water resistance to the AlN filler surface to some extent, improve the familiarity between the AlN filler surface and the resin, and prevent water from entering the AlN filler / resin interface. There is a certain effect in preventing sum (hydrolysis). However, since the adhesion as a film is weak and the film quality is hard, cracks and interfacial peeling are likely to occur on the surface, and the durability against stress such as the kneading process of AlN filler is insufficient, and a stable protective film can be produced. It was difficult.

  Phosphoric acid treatment agents can form a very strong water-resistant layer on the AlN filler surface, but it is very difficult to completely remove the phosphoric acid content. Since the problem of corrosion of copper wiring and the like occurs, its use is limited such as use in a place where it does not come into contact with metal.

  The most effective method is to use silicone oil and form a protective layer on the surface of the AlN filler by high-temperature baking, but the process is cumbersome, special and cannot be performed easily, and the processing cost is expensive. There has been a problem of reducing the thermal conductivity, which is a characteristic.

  In addition, various silane-based materials have been studied to further improve the problem of silane coupling agent treatment and silicone oil baking treatment. It was still difficult to obtain a stable heat dissipation material over a long period of time by uniformly dispersing it in a siloxane-based resin or an epoxy resin (Patent Documents 1 to 3).

JP 2013-091680 A JP 2011-153252 A JP 2011-153253 A

  As a method for solving the problems of the AlN filler as described above, an attempt has been made to cover the surface of the AlN filler with a silicone-based polymer and the like to suppress hydrolysis of the surface of the AlN filler. Problems still exist when coating the surface of an AlN filler with a silicone-based hybrid prepolymer prepared as the main raw material.

  The hybrid polymer obtained from the above silicone-based hybrid prepolymer has characteristics such as flexibility, water repellency, releasability, etc. of silicone resin as an organic component, and adhesiveness of alkoxysilane oligomer introduced as an inorganic component for the purpose of crosslinking. It has been proposed as a material having high heat resistance and flexibility even at a continuous use temperature of 200 ° C. or higher.

  However, even if such a silicone-based hybrid prepolymer is used, a surface treatment that does not deteriorate the filler surface is not easy. As the AlN filler, particles having a particle size of about 1 μm synthesized by a reduction nitridation method or a direct nitridation method, particles grown from several μm to about 20 μm or more, and particles having a size of about 1 μm are used as primary particles. There are particles, etc., which are dispersed in a system or aqueous solvent, additives such as binders are added as appropriate to form a slurry, and granules granulated by a spray dryer are sintered in a high-temperature nitrogen atmosphere. The obtained AlN filler has many fine irregularities on the surface, and a simple surface treatment technique cannot form a thin protective layer on the surface layer, which tends to cause non-uniform film thickness, resulting in lack of durability. It becomes a protective film.

  In particular, silicone-based hybrid prepolymers that have been developed so far generally use a relatively high molecular weight PDMS raw material for the purpose of increasing heat resistance, and thus the prepared organic-inorganic hybrid prepolymer has a high viscosity. As a result of the difficulty of uniform surface treatment to fine irregularities, hydrolysis of the AlN filler surface sufficient to maintain the high thermal conductivity of the AlN filler could not be suppressed. In addition, due to the high viscosity, there is a problem that the coating film thickness by the surface treatment is increased and the thermal conductivity is lowered.

  In order to solve the conventional problems of the AlN filler and to provide a heat radiating member excellent in heat resistance and thermal conductivity, the present invention provides the resulting hybrid polymer on the surface of the AlN filler with heat resistance and flexibility. By forming a protective layer using a silicone-based hybrid prepolymer having both, the hydrolysis of the surface of the AlN filler is suppressed, and a decrease in thermal conductivity is prevented.

  The silicone-based hybrid polymer-coated AlN filler according to the present invention is a filler mainly composed of aluminum nitride whose surface is coated with a silicone-based hybrid polymer, and has an average particle size of 20 to 40 μm with respect to 50 mL of ion-exchanged water. The conductivity of water after adding 5 g of the filler and holding it under a saturated water vapor pressure of 121 ° C. for 50 hours is 350 μS / cm or less.

  By doing so, it is possible to obtain a silicone-based hybrid polymer-coated AlN filler in which hydrolysis of the filler surface is suppressed, the thermal conductivity of the AlN filler is not impaired, and the thermal conductivity of the composite resin as a heat radiating member is not impaired. it can.

  The silicone-based hybrid polymer-coated AlN filler according to the present invention is obtained by adding 5 g of the filler having an average particle size of 20 to 40 μm to 50 mL of ion-exchanged water, and maintaining the pH of the water after being held at a saturated water vapor pressure of 121 ° C. for 50 hours. The value is preferably 10 or less.

ｍは数平均分子量（Ｍｎ）＝５００〜３，０００を満たし得る整数であり、一定の範囲の整数ｍの分子が混在する。

ｎは４〜１０の整数、Ｒは炭素数１〜３のアルキル基を示す。In the silicone-based hybrid polymer-coated AlN filler according to the present invention, the silicone-based hybrid polymer has a polydimethylsiloxane having a number average molecular weight (Mn) represented by the following general formula (1) of 500 to 3,000, A solidified product containing a reaction product of a tetraalkoxysilane oligomer represented by the following general formula (2) and / or a hydrolyzate thereof is preferable.

m is an integer capable of satisfying the number average molecular weight (Mn) = 500 to 3,000, and molecules of an integer m in a certain range are mixed.

n represents an integer of 4 to 10, and R represents an alkyl group having 1 to 3 carbon atoms.

  By doing in this way, deterioration of a filler is prevented and it becomes possible to produce a highly functional heat dissipation member.

  Such a silicone-based hybrid prepolymer has a reactive silanol group (OH group) or an alkoxy group (OR group) at the terminal or side chain. These functional groups easily react with reactive functional groups (Al—OH groups) present on the surface of the AlN filler in the presence of heat or moisture to form stable inorganic bonds (Al—O—Si—). O-). By this bond, a direct bond with the AlN surface is formed and an effect as a protective film is exhibited. Since the effect is exhibited with a relatively thin film as the intermediate protective film, the thermal conductivity does not decrease. Since the coating has a PDMS skeleton, it is flexible and relieves mechanical external stress, and hardly breaks or peels off. The bond formed between the surface of the AlN filler is thermally stable and can be stably used as a heat radiating member up to a high temperature of about 250 ° C.

  In the present specification, the number average molecular weight (Mn) indicates a molecular weight measured by gel permeation chromatography (GPC method) using polystyrene as a standard substance and tetrahydrofuran as an eluent.

  In addition, the silicone-based hybrid polymer-coated AlN filler of the present invention has many methyl groups arranged in the polymer molecular skeleton, and its high water repellency effect has the effect of preventing moisture from entering the silicone-based hybrid polymer / AlN filler interface. large. This is also one of the factors that can suppress hydrolysis of the AlN filler.

  In the silicone-based hybrid polymer-coated AlN filler according to the present invention, the number average molecular weight (Mn) of the polydimethylsiloxane represented by the general formula (1) is more preferably 600 to 2,000.

  The silicone-based hybrid polymer-coated AlN filler according to the present invention more preferably has an average particle size of 25 to 35 μm.

  In the silicone-based hybrid polymer-coated AlN filler according to the present invention, the mass ratio of the AlN filler coated on the silicone-based hybrid polymer and the silicone-based hybrid prepolymer is such that the silicone-based hybrid prepolymer 2 is 100 parts by mass of the AlN filler. It is preferable that it is -10 mass parts.

  The heat dissipation member according to the present invention includes any of the above-described silicone-based hybrid polymer-coated AlN fillers.

  As described above, according to the present invention, it is possible to provide a silicone-based hybrid polymer-coated AlN filler that exhibits high thermal conductivity and high heat resistance. Further, according to the present invention, it is possible to provide a heat dissipating member that can be used stably without being affected by the environment for a long period of time and has little change in characteristics due to the hydrolysis of the filler.

<AlN: Aluminum nitride>
Aluminum nitride, insulating and high in thermal conductivity. The primary particles synthesized by the reduction nitriding method or the direct nitriding method may be used as they are, but the granulated particles by a spray dryer or the like can be sintered and used as a so-called AlN sintered filler. In the granulation method using a spray dryer, the particle size of the granules can be controlled by adjusting the spraying conditions of the spray dryer, and as a result, an AlN sintered filler having various particle size distributions is produced. Is possible. In the present invention, the AlN filler includes a small amount of Y ₂ O ₃ added for the purpose of a sintering aid, and also includes a small amount of BN added for the purpose of particle size control.

<Silicone hybrid polymer coated AlN filler>
When an AlN filler is dispersed in a resin material to form a heat radiating member, hydrolysis of the filler is suppressed by coating with a silicone-based hybrid polymer. This inhibitory effect can be evaluated by the conductivity (change) of water when the silicone-based hybrid polymer-coated AlN filler is added to ion-exchanged water and treated under pressure by an autoclave or the like. The inventors of the present invention added 5 g of the AlN filler having an average particle size of 20 to 40 μm to 50 mL of ion-exchanged water, and the electric conductivity of water when maintained at 121 ° C. under a saturated water vapor pressure (2 atm) for 50 hours was 350 μS / If the AlN filler is dispersed in various resin materials such as silicone resin, epoxy resin, nylon resin, especially epoxy resin, and heat dissipation member is obtained, the heat conduction can be reduced. It was found that the deterioration of the property is sufficiently suppressed.

  Moreover, when the pH value of water was 10 or less by the same evaluation, it discovered that the heat radiating member by which deterioration of conductive heat property was fully suppressed was more reliably ensured.

<Silicone hybrid prepolymer>
The polydimethylsiloxane (hereinafter referred to as PDMS) used as a raw material for the silicone-based hybrid prepolymer used in the present invention has a number average molecular weight (Mn) represented by the general formula (1) of 500 to 3,000. Is preferred.

ここで、ｍは数平均分子量（Ｍｎ）＝５００〜３，０００を満たし得る整数であり、一定の範囲の整数ｍの分子が混在する。なお、両末端シラノール基（Ｓｉ−ＯＨ基）を有するＰＤＭＳを用いることが好ましいが、加水分解により容易にシラノール基になる末端アルコキシ基を有するＰＤＭＳを用いても同様の効果が見込まれる。

Here, m is an integer that can satisfy the number average molecular weight (Mn) = 500 to 3,000, and molecules of an integer m in a certain range are mixed. In addition, although it is preferable to use PDMS which has both terminal silanol groups (Si-OH group), the same effect is anticipated even if it uses PDMS which has the terminal alkoxy group which becomes a silanol group easily by hydrolysis.

  Since the viscosity of the silicone hybrid prepolymer prepared is affected by the average molecular weight of the PDMS used as a raw material, the effect of protecting the surface of nitride fillers such as AlN in silicone hybrid prepolymers prepared from high molecular weight PDMS Is difficult to express. As a result of the examination, a good surface treatment effect was obtained when the number average molecular weight (Mn) was in the range of 500 to 3,000. If the number average molecular weight (Mn) is less than 500, the resulting polymer coating is not sufficiently flexible, and the protective layer (coating) is hard, so that cracks are likely to occur, and there is a risk of peeling off from the AlN filler surface. On the other hand, when a silicone-based hybrid prepolymer prepared from PDMS having an average molecular weight exceeding 3,000 is used, it cannot follow the fine irregularities on the surface of the AlN filler due to high viscosity, making it difficult to sufficiently adhere to the surface. There is a fear. Considering the flexibility and adhesion of the protective layer (coating), the average molecular weight of PDMS is more preferably 600 to 2,000.

<Measurement of average molecular weight of polysiloxane (polydimethylsiloxane)>
The average molecular weight was measured by gel permeation chromatography (GPC method), and Mn (number average molecular weight) was defined as the average molecular weight. Polystyrene equivalent molecular weight was measured using polystyrene as a standard sample.
In addition, the polystyrene conversion molecular weight measurement by GPC method shall be performed on the following measurement conditions.
a) Measuring instrument: Tosoh HLC-8220GPC
b) Column: Tosoh TSK-gel Super H-RC 2
Three TSK-gel Super HZ2000
1 TSK-gel Super HZ4000 c) Oven temperature: 40 ° C
d) Eluent: Tetrahydrofuran (THF) 0.35 mL / min
e) Standard sample: Polystyrene f) Injection volume: 10 μL
g) Concentration: 1 wt%
h) Sample preparation: Tetrahydrofuran (THF) as a solvent was allowed to stand at room temperature for dissolution.
i) Calibration: A calibration curve was prepared using a standard sample at the time of measurement.

  What is blended as an inorganic component of the silicone-based hybrid prepolymer is an alkoxysilane oligomer represented by the general formula (2) and / or a hydrolyzate thereof.

ここで、ｎは４〜１０の整数であり、Ｒは炭素数１〜３のアルキル基より選ばれ、全て同一でも異なっていてもよい。好ましく用いられる形態は、Ｒはエチル基もしくはメチル基である。これらアルコキシ基は、一部が加水分解によってシラノール基となるため、分子内に水酸基とアルコキシ基が混在している状況が考えられる。

Here, n is an integer of 4 to 10, R is selected from an alkyl group having 1 to 3 carbon atoms, and they may all be the same or different. In a form preferably used, R is an ethyl group or a methyl group. Since some of these alkoxy groups become silanol groups by hydrolysis, a situation in which a hydroxyl group and an alkoxy group are mixed in the molecule can be considered.

  The prepared silicone-based hybrid prepolymer has a high concentration as a stock solution, and when used as it is, it becomes thick as a protective film, resulting in a decrease in thermal conductivity and aggregation of fillers. Therefore, it is desirable to appropriately dilute with a solvent and perform surface treatment. The solvent is not particularly limited as long as it is highly compatible with the silicone-based hybrid prepolymer. Toluene, xylene, tert-butyl alcohol, heptane, methyl ethyl ketone, etc. are desirable. Depending on the application and the form of the AlN filler, the silicone may be used. It is desirable to dilute the system hybrid prepolymer so that the total amount of the diluted hybrid prepolymer sol is 10 wt% or less. If the concentration is higher than that, there is a problem that the effect of sufficiently protecting the fine uneven surface of the AlN surface cannot be obtained, or the film becomes thick and the heat conduction characteristics deteriorate.

  For the surface treatment, an appropriate amount of AlN filler is blended in the silicone-based hybrid prepolymer (sol) solution diluted with the above solvent, and the AlN filler surface treatment is carried out by stirring treatment. There are no particular restrictions on the mixing method, and various methods such as stirrer stirring, mixing stirring with stirring blades, and planetary biaxial centrifugal stirring are possible. However, it is necessary to disperse the AlN filler subjected to the surface treatment sufficiently homogeneously in the diluted hybrid prepolymer to sufficiently wet the AlN surface.

  After the surface treatment, the solvent is volatilized using a rotary evaporator or the like, and the AlN filler is repeatedly dried, crushed, sintered and crushed to obtain an AlN filler surface-treated with a silicone-based hybrid polymer. In addition, since exposure of a torn surface occurs at the time of crushing, it is also desirable to repeat these series of processes several times.

[Manufacture of silicone-based hybrid prepolymers]
In the present invention, a silicone-based hybrid prepolymer is obtained by a condensation reaction of PDMS represented by the general formula (1) and a tetraalkoxysilane oligomer represented by the general formula (2) and / or a hydrolyzate thereof (hereinafter, silane oligomer). Is prepared (about 120 ° C.) in the presence of a metal compound catalyst.

  Regarding metal compound catalysts, metal organic acid salts (particularly carboxylates), alkoxides, alkylated metal compounds, acetylacetonate complexes, ethyl acetoacetate complexes, metal alkoxides in which some of the alkoxy groups are acetylacetonate or ethylacetate. Examples include metal complexes substituted with acetate. Specifically, for example, zinc octylate (zinc 2-ethylhexanoate), zirconium octylate (zirconium 2-ethylhexanoate), zirconyl octylate (2-ethylhexanoate) Zirconyl), dibutyltin diurarate, dibutyltin diacetate, dibutyltin bisacetylacetonate, tetra (2-ethylhexyl) titanate, titanium tetra n-butoxide, titanium tetraisopropoxide, titanium diisopropoxybis (ethylacetoa Tate), titanium tetraacetylacetonate, titanium di-2-ethylhexoxybis (2-ethyl-3-hydroxyhexoxide), titanium diisopropoxybis (acetylacetonate), zirconium tetra n-propoxide, zirconium tetra n -Butoxide, zirconium tetraacetylacetonate, zirconium tributoxymonoacetylacetonate, zirconium dibutoxybis (ethylacetoacetate) and the like are exemplified. Although there is no particular limitation, Sn-based catalysts such as dibutyltin diurarate, dibutyltin diacetate, and dibutyltin bisacetylacetonate are desirable in terms of reactivity and stability.

  When performing the above condensation reaction, in order to perform stable hydrolysis of the tetraalkoxysilane oligomer, the hydrolysis and condensation reaction is performed by heating in an atmosphere filled with an inert gas inside the vessel used for the reaction. It is desirable to do. Examples of the inert gas include Group 18 elements (helium, neon, argon, krypton, xenon, etc.) that are nitrogen gas and rare gases. These gases may be mixed and used. As the hydrolysis method, various methods such as dripping and spraying an appropriate amount of water and introducing water vapor can be considered. Depending on the case, a synthesis method such as sending dry air whose humidity is controlled into the synthesis container or reducing the pressure at regular intervals is also conceivable.

  The silicone-based hybrid prepolymer is obtained by subjecting a mixture containing the tetraalkoxylane oligomer and the PDMS to hydrolysis and condensation reaction in the presence of the condensation catalyst in the inert gas atmosphere. That is, the alkoxy group of the tetraalkoxylane oligomer subjected to hydrolysis becomes a silanol group, and a dehydration reaction or a dealcoholization reaction with the silanol group at the PDMS terminal proceeds in the presence of an inert gas. By using the silane oligomer, the condensation reaction between PDMS and the hydrolyzed oligomer can be performed smoothly without accelerating the single condensation that tends to occur with the silane monomer. As a result, the oligomer and the PDMS react homogeneously, and the condensation reaction proceeds smoothly.

  In obtaining the silicone-based hybrid prepolymer, it is possible to add a stabilizing solvent to a raw material liquid composed of a mixture containing the alkoxide and the PDMS in the inert gas atmosphere. Is also desired. As this stabilizing solvent, tert-butyl alcohol, heptane, toluene, xylene, methyl ethyl ketone, etc. have high compatibility, and can be used as a diluting solvent as described above.

[Combination ratio]
The blending ratio of the PDMS to the tetraalkoxysilane oligomer (PDMS / silane oligomer) is 0.05 to 5 (PDMS / silane oligomer = 1/20 to 1 / 0.2) as a molar ratio, preferably 0. 125 to 2.0 (PDMS / silane oligomer = 1/8 to 1 / 0.5), more preferably 0.25 to 1.0 (PDMS / silane oligomer = 1/4 to 1/1) It is desirable that However, it is desirable to change this blending ratio in accordance with the functional group amount of the AlN filler used. When the amount of functional groups is large, it is ideal to increase the compounding ratio of the tetraalkoxysilane oligomer within the above range. When the PDMS / oligomer molar ratio is in the above range, the dehydration condensation reaction is carried out smoothly, and gelation during or after the reaction is unlikely to occur. A stable sol with no residual is obtained.

  The molar ratio here refers to the number average molecular weight (Mn) of PDMS measured by gel permeation chromatography (GPC method) using polystyrene as a standard substance and tetrahydrofuran as an eluent, and the oligomer of tetraalkoxysilane. A molar ratio calculated based on purity and average molecular weight.

<Surface treatment of AlN filler>
The AlN filler is mixed with the hybrid prepolymer sol diluted with a solvent so that the silicone-based hybrid prepolymer is 2 to 10 parts by mass, preferably 2.5 to 6 parts by mass with respect to 100 parts by mass of the AlN filler, Stir and mix. The treatment is continued at room temperature for 5 hours or longer, desirably 10 hours or longer, more desirably 24 hours or longer. Thereafter, the solvent is removed under reduced pressure to obtain an AlN aggregate with the hybrid prepolymer attached to the surface. By heat-treating this aggregate, a highly durable AlN filler having a hybrid prepolymer cured layer formed on the surface can be obtained. Since this AlN filler is excellent in water resistance, characteristics such as thermal conductivity do not deteriorate when added to a hydrophilic resin such as an epoxy resin.

  The silicone-based hybrid polymer-coated AlN filler of the present invention is much higher in water resistance than the conventional methods using various coupling agents, silicone oils, and silicone resins, and is a metal member such as a phosphoric acid-based treatment agent. Because it does not contain any components that corrode the resin, it can also be used for hydrophilic resins such as epoxy resins, and water-absorbing resins such as silicone rubber and nylon resins, and the application and application areas are limited. Can be used without being. Furthermore, the coating film rich in flexibility does not break even in high-stress processing such as resin kneading.

The present invention will be described more specifically with reference to examples.
In the examples, “part” and “%” are based on mass (part by mass, mass%) unless otherwise specified. Further, the present invention is not limited to these examples.

<Synthesis of silicone hybrid prepolymer>
(Preparation of solution A)
A reaction vessel equipped with a stirrer, a thermometer, and a dropping line was sufficiently filled with nitrogen gas. At this time, what was manufactured with the nitrogen gas manufacturing apparatus (Japan Unix Co., Ltd. UNX-200) was used as nitrogen gas. The synthesis was performed on a scale of about 1 kg using a 2 L container.

  Next, in the reaction vessel sufficiently filled with the nitrogen gas, polydimethylsiloxane (PDMS) having silanol groups at both ends and an oligomer of tetraalkoxysilane are placed in the reaction vessel, and the synthesis vessel is heated to 120 ° C. After raising the temperature, a condensation catalyst was added, and the reaction was further stirred at 120 ° C. for 30 minutes. Thereafter, the mixture was naturally cooled to room temperature, and tert-butyl alcohol was blended as a diluent solvent to obtain Liquid A.

(Preparation of liquid B)
The tetraalkoxylane oligomer and the organometallic compound were put into a reaction vessel different from the above and stirred at room temperature to obtain a transparent liquid B.

Example 1
(Preparation of solution A-1)
Raw materials used were PDMS; Momentive's both-end silanol polydimethylsiloxane XC96-723 (number average molecular weight: Mn = 680), TEOS oligomer; Ethyl silicate, Tama Chemical Co., Ltd. silicate 40: tetraethoxysilane Oligomers (oligomer purity: 70% by mass, average molecular weight: 745), diluting solvent; tert-butyl alcohol: Wako Pure Chemical Industries, Ltd., Wako special grade, condensation catalyst; dibutyltin dilaurate, joint Using KS-1260 manufactured by Yakuhin Co., Ltd., synthesis was performed at a scale of about 1 kg. The blending amount of each raw material is as follows.

  Molar ratio: PDMS (XC96-723) is 185.6 g, TEOS oligomer (silicate 40) is 813.4 g, and the molar ratio of XC96-723 and silicate 40 oligomer is 1: 2.8. Add 1.0 g of dibutyltin dilaurate as a condensation catalyst. Contains 150 g of tert-butyl alcohol as a diluent solvent.

(Preparation of liquid B)
The raw materials used were TEOS oligomers; silicate 45 manufactured by Tama Chemical Industry Co., Ltd .: oligomers that are linear 8- to 10-mers of tetraethoxysilane (oligomer purity: 95% by mass, average molecular weight: 1282), organometallic compounds; 2-ethyl hexanoate zinc: Nikka Octix zinc 18% (molecular weight: 351.79) manufactured by Nippon Chemical Industry Co., Ltd., diluting solvent; tert-butyl alcohol. The blending amounts are as follows.

  Molar ratio: 76 g of TEOS oligomer (silicate 45) and 24 g of zinc 2-ethylhexanoate (Nikka octix zinc 18%). The molar ratio of ethylsilicate 45 to zinc 2-ethylhexanoate is 1: 1.2. 10g of tert-butyl alcohol is used as a dilution solvent.

(Preparation of surface treatment agent C-1 solution)
The whole amount of A-1 liquid and the whole quantity of B liquid were mixed and stirred, and C-1 liquid was obtained.

(Surface treatment method)
C-1 solution is added to 100 parts by mass of filler (aluminum nitride: FAN-f30 manufactured by Furukawa Denshi, average particle size of about 30 μm) so that the prepolymer becomes 3 parts by mass, and further 100 parts by mass of tert-butyl alcohol And stirred at 40 ° C. for 24 hours, and then dried under reduced pressure on a rotary evaporator to obtain a powder state. Thereafter, heat treatment was performed at 200 ° C. for 4 hours, and further pulverization was performed. The average particle diameter of the AlN filler coated with the silicone-based hybrid polymer was also about 30 μm.

  In addition, the average particle diameter was measured by a dry method using a laser diffraction particle size distribution measuring apparatus Mastersizer 3000 manufactured by Spectris Co., Ltd.

(Examples 2 to 4)
(Preparation of A-2, 3, 4 solutions)
The raw materials used were PDMS: Silent Polydimethylsiloxane XC96-723 (number average molecular weight: Mn = 680) manufactured by Momentive, TEOS oligomer; ethyl silicate, silicate 45 manufactured by Tama Chemical Industries, Ltd. Oligomers (oligomer purity: 95% by mass, average molecular weight: 1282), diluting solvent; tert-butyl alcohol: Wako Pure Chemical Industries, Ltd., Wako special grade, condensation catalyst; dibutyltin dilaurate, joint Using KS-1260 manufactured by Yakuhin Co., Ltd., synthesis was performed at a scale of about 1 kg. The blending amount of each raw material is as follows.

  Liquid A-2: molar ratio: PDMS (XC96-723) was 117.0 g, TEOS oligomer (silicate 45) was 882.4 g, and the molar ratio of pure oligomers of XC96-723 and silicate 45 was 1: 3.8. . Add 0.65 g of dibutyltin dilaurate as a condensation catalyst. Contains 150 g of tert-butyl alcohol as a diluent solvent.

  Liquid A-3: Molar ratio: PDMS (XC96-723) is 209.4 g, TEOS oligomer (silicate 45) is 789.5 g, and the molar ratio of pure XC96-723 and silicate 45 oligomer is 1: 1.9. Add 1.2 g of dibutyltin dilaurate as condensation catalyst. Contains 150 g of tert-butyl alcohol as a diluent solvent.

  Liquid A-4: Molar ratio: PDMS (XC96-723) is 150.1 g, TEOS oligomer (silicate 45) is 849.0 g, and the molar ratio of XC96-723 and silicate 45 oligomer is 1: 2.9. Add 0.8 g of dibutyltin dilaurate as a condensation catalyst. Contains 150 g of tert-butyl alcohol as a diluent solvent.

(Preparation of surface treatment agents C-2, 3, and 4)
The total amount of each of A-2, 3 and 4 and the total amount of B were mixed and stirred to obtain C-2, 3 and 4 solutions.

(Surface treatment method)
C-2, 3 and 4 liquids were added to 100 parts by mass of filler (aluminum nitride: FAN-f30 manufactured by Furukawa Electronics) so that the prepolymer would be 3 parts by mass, In addition, the mixture was stirred at 40 ° C. for 24 hours and then dried under reduced pressure using a rotary evaporator to obtain a powder state. Then, it heat-processed at 200 degreeC for 4 hours, and also performed the crushing process. The average particle diameter of the AlN filler coated with the silicone-based hybrid polymer was also about 30 μm.

(Example 5)
(Preparation of A-5 solution)
The raw materials used were PDMS; Gelest's both-end silanol polydimethylsiloxane DMS-S14 (number average molecular weight: Mn = 1,500), TEOS oligomer; Ethyl silicate, Tama Chemical Co., Ltd. silicate 45: Oligomer (oligomer purity: 95% by mass, average molecular weight: 1282), diluting solvent; tert-butyl alcohol: Wako Pure Chemical Industries, Ltd., Wako special grade, condensation catalyst; dibutyltin dilaurate Using KS-1260 manufactured by Kyodo Yakuhin Co., Ltd., synthesis was performed at a scale of about 1 kg. The blending amount of each raw material is as follows.

  Molar ratio: PDMS (DMS-S14) was 226.2 g, TEOS oligomer (silicate 45) was 773.2 g, and the molar ratio of pure oligomers of DMS-S14 and silicate 45 was 1: 3.8. Add 0.6 g of dibutyltin dilaurate as a condensation catalyst. As a diluent solvent, 150 g of tert-butyl alcohol is blended.

(Preparation of surface treatment agent C-5 solution)
The whole amount of A-5 liquid and the whole quantity of B liquid were mixed and stirred, and C-5 liquid was obtained.

(Surface treatment method)
Except that the prepolymer amount is 5 parts by mass, the filler (aluminum nitride: FAN-f30 manufactured by Furukawa Denshi) is surface-treated with the C-5 solution, as in the case of the C-1 to C-4 solutions, and the average particle diameter An AlN filler coated with a silicone-based hybrid polymer of about 30 μm was obtained.

(Comparative Example 1)
(Preparation of A-6 solution)
The raw materials used were PDMS; Gelest, both-end silanol polydimethylsiloxane DMS-S15 (number average molecular weight: Mn = 3,500), oligomer; ethyl silicate, Tama Chemical Co., Ltd. silicate 45: tetraethoxysilane Oligomers in the form of chain 8-10mers (oligomer purity: 95% by mass, average molecular weight: 1282), diluent solvent; tert-butyl alcohol: Wako Pure Chemical Industries, Ltd., Wako Special Grade, condensation catalyst; dibutyltin dilaurate, Synthesis was carried out at a scale of about 1 kg using KS-1260 manufactured by Kyodo Pharmaceutical Co., Ltd. The blending amount of each raw material is as follows.

  Molar ratio: PDMS (DMS-S15) is 405.5 g, TEOS oligomer (silicate 45) is 594.1 g, and the molar ratio of pure oligomers of DMS-S15 and silicate 45 is 1: 3.8. Add 0.4 g of dibutyltin dilaurate as condensation catalyst. As a diluent solvent, 150 g of tert-butyl alcohol is blended.

(Preparation of surface treatment agent C-6 solution)
The whole amount of A-6 liquid and the whole quantity of B liquid were mixed and stirred, and C-6 liquid was obtained.

(Surface treatment method)
Except that the amount of prepolymer is 10 parts by mass, the filler (aluminum nitride: FAN-f30 manufactured by Furukawa Electronics Co., Ltd.) is surface-treated with the C-6 solution as in the case of the C-1 to C-4 solutions, and the average particle diameter An AlN filler coated with a silicone-based hybrid polymer of about 30 μm was obtained.

(Comparative Example 2)
(Preparation of solution A-7)
PDMS; JNC double-end silanol polydimethylsiloxane FM9915 (number average molecular weight: Mn = 5,000), TEOS oligomer; ethyl silicate, Tama Chemical Co., Ltd. silicate 40: tetraethoxysilane linear 4-6 amount Oligomer (oligomer purity: 70% by mass, average molecular weight: 745), diluting solvent; tert-butyl alcohol: Wako Pure Chemical Industries, Ltd., Wako special grade, condensation catalyst; dibutyltin dilaurate, KS manufactured by Kyodo Pharmaceutical Co., Ltd. The synthesis was carried out using -1260 with a scale of about 1 kg. The blending amount of each raw material is as follows.

  Molar ratio: PDMS (FM9915) was 626.3 g, TEOS oligomer (silicate 40) was 373.3 g, and the molar ratio of FM9915 to silicate 40 oligomer was 1: 2.8. Dibutyltin dilaurate 0.5g is added as a condensation catalyst. As a diluent solvent, 150 g of tert-butyl alcohol is blended.

(Preparation of surface treatment agent C-7 solution)
The total amount of A-7 solution and the entire amount of B solution were mixed and stirred to obtain C-7 solution.

(Surface treatment method)
Similar to the case of C-1 to C-4 liquids except that the amount of prepolymer is 10 parts by mass, the filler (aluminum nitride: FAN-f30 manufactured by Furukawa Denshi) is surface-treated with liquid C-7, and the average particle diameter An AlN filler coated with a silicone-based hybrid polymer of about 30 μm was obtained.

(Comparative Example 3)
(Preparation of A-8 'solution)
PDMS; JNC's double-ended silanol polydimethylsiloxane FM9926 (number average molecular weight: Mn = 20,000), oligomer; ethyl silicate, Tama Chemical Co., Ltd. silicate 40: tetraethoxysilane linear 4- to 6-mer Oligomer (oligomer purity: 70% by mass, average molecular weight: 745), diluting solvent; tert-butyl alcohol: Wako Pure Chemical Industries, Ltd., Wako Special Grade, condensation catalyst; dibutyltin dilaurate, Kyodo Pharmaceutical Co., Ltd., KS- 1260 was used and the synthesis was performed at a scale of about 1 kg. The blending amount of each raw material is as follows.

Molar ratio: 609.1 g of PDMS (FM9926) and 90.8 g of oligomer (silicate 40), and the molar ratio of pure oligomer of silicate 40 to FM9926 is 1: 2.8. As a condensation catalyst, 0.18 g of dibutyltin dilaurate was added and 105 g of tert-butyl alcohol was added as a dilution solvent.
(Preparation of A-8 solution)
345 g of the A-7 solution used in Comparative Example 3 and 805 g of the A-8 ′ solution were mixed to prepare 1150 g of sol, which was designated as A-8 solution.

(Preparation of surface treatment agent C-8 solution)
The whole amount of A-8 liquid and the whole quantity of B liquid were mixed and stirred, and C-8 liquid was obtained.

(Surface treatment method)
Except that the amount of prepolymer is 10 parts by mass, the filler (aluminum nitride: FAN-f30 manufactured by Furukawa Electronics Co., Ltd.) is surface-treated with the C-8 solution as in the case of the C-1 to C-4 solutions, and the average particle diameter An AlN filler coated with a silicone-based hybrid polymer of about 30 μm was obtained.

(Comparative Example 4)
The surface treatment was performed only with the TEOS oligomer component, assuming that the molecular weight was low and the PDMS component was not included. The raw material used was an oligomer (oligomer purity: 95 mass%, average molecular weight: 1282) which is a linear 8- to 10-mer of TEOS oligomer: silicate 45: tetraethoxysilane manufactured by Tama Chemical Co., Ltd.

(Surface treatment method)
Add silicate 45 manufactured by Tama Chemical Industry Co., Ltd. to 10 parts by mass with respect to 100 parts by mass of filler (aluminum nitride: FAN-f30 manufactured by Furukawa Electronics), and stir while heating to obtain a dry powder state. Thereafter, a final heat treatment was performed at 200 ° C. for 4 hours to obtain an AlN filler coated with a silicone-based hybrid having an average particle size of about 30 μm.

(Comparative Examples 5-7)
Three types of aluminum nitride filler not subjected to surface treatment: H grade (average particle size 1 μm), FAN-f30 (average particle size 30 μm), FAN-f80 (average particle size 80 μm) (all manufactured by Furukawa Denshi) Prepared.

<Evaluation method>
[About pH measurement method and conductivity measurement method]
Each surface-treated AlN filler prepared in Examples 1 to 5 and Comparative Examples 1 to 4 and 5 g of each surface untreated AlN filler prepared in Comparative Examples 5 to 7 were placed in a polytetrafluoroethylene container, and 50 mL of ion-exchanged water was added. In addition, the glass container mouth was covered with aluminum foil, and the autoclave was held at 121 ° C. for 50 hours. Then, it was allowed to stand until it reached room temperature, and the pH and conductivity of the filtrate were measured.

  The pH and conductivity were obtained by measuring the water values before and after the treatment using a pH composite measuring instrument manufactured by Eutech. Tables 1 to 3 collectively show the compositions and evaluation results of Examples and Comparative Examples.

<Evaluation results>
From the measurement results of pH and conductivity, an AlN filler coated with a silicone hybrid polymer prepared by condensation reaction with a TEOS oligomer using a PDMS having a number average molecular weight of 1,500 or less as a raw material PDMS (Examples 1 to 5) ) Shows that hydrolysis is suppressed as compared with the surface-treated fillers of Comparative Examples 1 to 4. AlN fillers (Comparative Examples 1 to 3) coated with a silicone-based hybrid polymer prepared by using a raw material PDMS having a number average molecular weight of 3,500 or more have a small hydrolysis inhibiting effect. Moreover, since only the TEOS oligomer (Comparative Example 4) had insufficient film flexibility, it was equivalent to the untreated filler (Comparative Examples 5 to 7). In addition, it turned out that the influence of a particle size is not large with respect to pH change and electrical conductivity change by surface hydrolysis from the result of an untreated AlN filler.

<Evaluation of thermal conductivity of heat dissipation member>
(Evaluation 1)
As an example of a heat radiating member including a silicone-based hybrid polymer-coated AlN filler according to the present invention, a heat conductive sheet was prepared as follows. That is, an example in which 100 parts of an epoxy resin (epoxy resin Epicoat 828 manufactured by Mitsubishi Chemical Corporation) is added to a polypropylene beaker, 10 parts of a curing agent (Ajinomoto Fine Techno Curing Agent Amicure AH-154), and an average particle size of about 30 μm. 320 parts of the silicone-based hybrid polymer-coated AlN filler obtained in 3 (AlN filler: FAN-f30 manufactured by Furukawa Electronics Co., Ltd.) was added and mixed for 10 minutes with a propeller stirrer so as to be uniform. The resulting compound was kneaded for 10 minutes using a ceramic three roll mill and collected. The collected compound was sandwiched between polymethylpentene resin films and molded into a sheet shape having a size of about 100 mm × 150 mm and a thickness of 0.5 mm with a stretching roller. The molded sheet was heated in a hot air circulation dryer at 150 ° C. for 6 hours to obtain a rubber sheet-like heat conductive sheet. The thermal conductivity of this sheet was 3.0 W · m ⁻¹ · K ⁻¹ .

When the thermal conductivity of this heat conductive sheet was measured after 200 hours of PCT (pure water and sample sheet were put in an autoclave, 121 ° C. × 100% RH: 2 atm), 3.0 W · m ⁻¹ · K ^{− 1} No deterioration was observed.

(Evaluation 2)
A rubber sheet-like heat conductive sheet was obtained in the same manner as in Evaluation 1 except that the silicone-based hybrid polymer-coated AlN filler obtained in Example 2 was used as the silicone-based hybrid polymer-coated AlN filler. The thermal conductivity of this sheet was 3.0 W · m ⁻¹ · K ⁻¹ .

When the thermal conductivity of this heat conductive sheet was measured after 200 hours of PCT (pure water and sample sheet were put in an autoclave and 121 ° C. × 100% RH: 2 atm), the thermal conductivity was 2.8 W · m ⁻¹ · K ^{−. 1} Almost no deterioration was observed.

  In Evaluation 1 and Evaluation 2, thermal conductivity was measured according to ASTM D5470 using T3ster DynTIM manufactured by Mentor Graphics Japan. Samples having a diameter of 12.8 mm and a thickness of 0.35 mm, 0.5 mm, 0.6 mm, 0.7 mm, and 0.8 mm were prepared. A predetermined load was applied to the sample, and the thermal resistance value was measured from the temperature difference between the upper and lower sides (thickness direction) and the power. From the graph of thickness and thermal resistance of the above five types of samples, contact thermal resistance component and thermal resistance component of the sheet are separated, and thermal conductivity is calculated from the thermal resistance value obtained by linear approximation of the thermal resistance component of the sheet. Calculated.

[Example of change]
The present invention is not limited only to the above-described embodiments, and modifications, deletions, and additions can be made without departing from the technical idea of the present invention that can be recognized by those skilled in the art from the claims and the description of the specification. It is.

  PDMS having different molecular weight distributions may be used as long as the number average molecular weight is within the above range. For example, if PDMS with a narrow molecular weight distribution and uniform molecular weight is used, a silicone-based hybrid prepolymer with very few unreacted sites can be obtained, and excellent durability and surface water repellency can be exhibited. .

  Further, the inert gas used for atmosphere replacement of the reaction vessel may have a purity of 80% or more and a moisture content of 20% or less.

  The present invention is summarized as follows.

  (1) The silicone-based hybrid polymer-coated AlN filler according to the present invention is a filler mainly composed of aluminum nitride whose surface is coated with a silicone-based hybrid polymer, and has an average particle size of 20 with respect to 50 mL of ion-exchanged water. The conductivity of water after adding 5 g of the filler of ˜40 μm and holding it under a saturated water vapor pressure of 121 ° C. for 50 hours is 350 μS / cm or less.

  (2) The silicone-based hybrid polymer-coated AlN filler according to the present invention is obtained by adding 5 g of the filler having an average particle size of 20 to 40 μm to 50 mL of ion-exchanged water, and holding it for 50 hours under a saturated water vapor pressure of 121 ° C. It is preferable that the pH value of water is 10 or less.

ｍは数平均分子量（Ｍｎ）＝５００〜３，０００を満たし得る整数であり、一定の範囲の整数ｍの分子が混在する。

ｎは４〜１０の整数、Ｒは炭素数１〜３のアルキル基を示す。(3) In the silicone-based hybrid polymer-coated AlN filler according to the present invention, the silicone-based hybrid polymer is a polydimethyl having a number average molecular weight (Mn) represented by the following general formula (1) of 500 to 3,000. A solidified product containing a reaction product of siloxane and a tetraalkoxysilane oligomer represented by the following general formula (2) and / or a hydrolyzate thereof is preferable.

m is an integer capable of satisfying the number average molecular weight (Mn) = 500 to 3,000, and molecules of an integer m in a certain range are mixed.

n represents an integer of 4 to 10, and R represents an alkyl group having 1 to 3 carbon atoms.

  (4) In the silicone-based hybrid polymer-coated AlN filler according to the present invention, the polydimethylsiloxane represented by the general formula (1) preferably has a number average molecular weight (Mn) of 600 to 2,000.

  (5) The silicone hybrid polymer-coated AlN filler according to the present invention preferably has an average particle size of 25 to 35 μm.

  (6) In the silicone-based hybrid polymer-coated AlN filler according to the present invention, the mass ratio of the AlN filler coated on the silicone-based hybrid polymer to the silicone-based hybrid prepolymer is 100 mass parts of the AlN filler. It is preferable that it is 2-10 mass parts of prepolymers.

  (7) The heat dissipation member according to the present invention includes the silicone-based hybrid polymer-coated AlN filler according to any one of the above (1) to (6).

If the silicone hybrid polymer-coated AlN filler according to the present invention is used, it is possible to provide a heat radiating member or a functional member with less environmental impact, that is, less deterioration in characteristics such as thermal conductivity due to hydrolysis of the AlN filler surface, Highly superior material design that combines heat resistance, flexibility and high thermal conductivity is possible.

Claims (7)

  It is a filler mainly composed of aluminum nitride whose surface is coated with a silicone-based hybrid polymer, and 5 g of the filler having an average particle diameter of 20 to 40 μm is added to 50 mL of ion-exchanged water, and 50% under a saturated water vapor pressure of 121 ° C. A silicone-based hybrid polymer-coated AlN filler having a water conductivity of 350 μS / cm or less after holding for a period of time.   The silicone according to claim 1, wherein the pH value of water after adding 5 g of the filler having an average particle diameter of 20 to 40 μm to 50 mL of ion-exchanged water and holding it under a saturated water vapor pressure of 121 ° C. for 50 hours is 10 or less. -Based hybrid polymer-coated AlN filler. The silicone-based hybrid polymer is a polydimethylsiloxane having a number average molecular weight (Mn) represented by the following general formula (1) of 500 to 3,000, and a tetraalkoxysilane oligomer represented by the following general formula (2) 3. The silicone-based hybrid polymer-coated AlN filler according to claim 1 or 2, which is a solidified product containing a reaction product with and / or a hydrolyzate thereof.

m is an integer capable of satisfying the number average molecular weight (Mn) = 500 to 3,000, and molecules of an integer m in a certain range are mixed.

n represents an integer of 4 to 10, and R represents an alkyl group having 1 to 3 carbon atoms.   The silicone-based hybrid polymer-coated AlN filler according to claim 3, wherein the polydimethylsiloxane represented by the general formula (1) has a number average molecular weight (Mn) of 600 to 2,000.   The silicone-based hybrid polymer-coated AlN filler according to any one of claims 1 to 4, wherein the average particle diameter is 25 to 35 µm.   The mass ratio of the AlN filler coated on the silicone hybrid polymer and the silicone hybrid prepolymer is 2 to 10 parts by mass of the silicone hybrid prepolymer with respect to 100 parts by mass of the AlN filler. The silicone-based hybrid polymer-coated AlN filler according to any one of 5 to 5.   A heat dissipation member comprising the silicone-based hybrid polymer-coated AlN filler according to any one of claims 1 to 6.