JP5895690B2 - Method for producing organic modified inorganic filler, organic modified inorganic filler, and thermally conductive silicone composition - Google Patents

Description

  The present invention relates to a method for producing an organically modified inorganic filler capable of improving fluidity when filled into various resins to obtain a resin composition, an organically modified inorganic filler produced by the production method, and The present invention relates to a heat conductive silicone composition using the organically modified inorganic filler.

  Many electronic components generate heat during use, which may reduce the performance of the electronic components. For this reason, a heat radiator such as a heat sink is attached to the electronic component. However, since the heat radiator is often a metal, the electronic component and the heat radiator are not closely adhered. In order to solve this problem, a method has been proposed in which a heat conductive resin composition is interposed between an electronic component and a heat dissipator to improve adhesion and efficiently release heat. However, in recent years, the performance of electronic components has been remarkably improved, and the amount of heat generation has been steadily increasing. Accordingly, there has been a further demand for higher thermal conductivity of the thermally conductive resin composition.

  In order to improve the thermal conductivity of the thermally conductive resin composition, it is necessary to fill a large amount of the thermally conductive inorganic filler. In order to fill a large amount of the thermally conductive inorganic filler, it is essential to increase the affinity between the thermally conductive inorganic filler and the resin. For example, the surface of the thermally conductive inorganic filler is modified with an organosilicon compound. A method for improving the dispersibility is proposed. Specifically, a proposal for modifying with an alkoxy group-containing siloxane (Japanese Patent Laid-Open No. 2004-262972 (Patent Document 1)), a proposal for modifying with an alkylalkoxysilane (Japanese Patent Laid-Open No. 11-209618 (Patent Document 2)) Patent No. 4514164 (Patent Document 3)). However, in Patent Document 1, it is necessary to use two specific organopolysiloxanes for surface modification of the inorganic filler, and the fluidity of the composition is not sufficiently improved. In Patent Documents 2 and 3, hexyltrimethoxysilane or the like is used, and there is a limit to improving the fluidity of the composition.

  In addition, a method of modifying the surface of an inorganic filler with an organic modifier having a functional group such as a carboxyl group, an amino group, or a hydroxyl group using water in a supercritical state or a subcritical state as a reaction field without using an organosilicon compound Has been proposed (Japanese Patent Laid-Open No. 2011-122030 (Patent Document 4)). As shown in Patent Document 4, a technique for modifying the surface of an inorganic filler using water in a supercritical state or a subcritical state as a reaction field dramatically improves the affinity between the inorganic filler and the resin. It has attracted attention in recent years. However, in Patent Document 4, if the organic modifier used for this purpose has a silanol group or a functional group that hydrolyzes to generate a silanol group, the effect tends to decrease due to the condensation reaction between the silanol groups. Organic modifiers are limited to those having no silanol groups or functional groups that hydrolyze to form silanol groups.

JP 2004-262972 A Japanese Patent Laid-Open No. 11-209618 Japanese Patent No. 4514164 JP 2011-122030 A

  The present invention has been made in view of the above circumstances. Even when an inorganic filler and an organic compound having a silanol group or a functional group that hydrolyzes to generate a silanol group are used, the resin, for example, an organopolysiloxane composition is used. Method for producing organic modified inorganic filler capable of efficiently improving fluidity of composition when filled, organic modified inorganic filler produced by the production method, and organic modified inorganic filler It aims at providing a heat conductive silicone composition.

In order to achieve the above object, the present invention provides the following method for producing an organically modified inorganic filler, an organically modified inorganic filler, and a thermally conductive silicone composition.
[1] Using water in a supercritical state or subcritical state at a temperature of 200 to 450 ° C. and a pressure of 10 to 40 MPa as a reaction field, an inorganic filler, CH ₃ — (CH ₂ ) _n —Si (CH ₃ ) ₂ — OH (n is an integer of 9), CH ₃ — (CH ₂ ) _n —Si (CH ₃ ) ₂ —OCH ₃ (n is an integer of 9), CH ₃ — (CH ₂ ) _n —Si (CH ₃ ) ₂ It is characterized by mixing and reacting with at least one organic compound selected from the group consisting of —NH—Si (CH ₃ ) ₂ — (CH ₂ ) _n —CH ₃ (n is an integer of 9). Manufacturing method of organic modified inorganic filler.
[2] The organically modified inorganic filler according to [1], wherein the inorganic filler is made of at least one material selected from the group consisting of metals, metal oxides, metal nitrides, metal carbides, and carbon allotropes. Manufacturing method.
[3] The inorganic filler is selected from aluminum, silver, copper, metallic silicon, alumina, zinc oxide, magnesium oxide, silicon dioxide, aluminum hydroxide, aluminum nitride, boron nitride, silicon carbide, diamond, graphite, and carbon nanotube. The manufacturing method of the organic modified inorganic filler as described in [2] which consists of at least 1 or more types of materials.
[4] The method for producing an organically modified inorganic filler according to [3], wherein the inorganic filler is made of alumina.

[ 5 ] A thermally conductive silicone comprising a step of producing an organic modified inorganic filler by the production method according to any one of [1] to [4], and mixing the obtained organic modified inorganic filler with an organopolysiloxane. A method for producing the composition.

  According to the present invention, water in a supercritical or subcritical state at a predetermined temperature and pressure is used as a reaction field, and has a thermally conductive inorganic filler and a functional group that generates a silanol group by hydrolysis or silanol group. By efficiently reacting a predetermined organic compound, it is possible to produce an organic modified inorganic filler capable of improving the fluidity of the composition when filled into a resin, and further using the organic modified inorganic filler. A thermally conductive silicone composition having excellent fluidity can be provided.

It is a figure which shows the measurement result by FT-IR of Example 1. FIG. It is a figure which shows the measurement result by TG-DTA of Example 1. FIG. It is a figure which shows the measurement result by FT-IR of Example 2. FIG. It is a figure which shows the measurement result by TG-DTA of Example 2. It is a figure which shows the measurement result by FT-IR of Example 3. It is a figure which shows the measurement result by TG-DTA of Example 3.

Embodiments of the present invention will be described below.
[Organic modified inorganic filler]
The organically modified inorganic filler according to the present invention is obtained by using water in a supercritical state or subcritical state at a temperature of 200 to 450 ° C. and a pressure of 10 to 40 MPa as a reaction field, and with an inorganic filler and a silanol group or hydrolyzing. A predetermined organic compound having a functional group that generates a silanol group is mixed and reacted.

Here, as the predetermined organic compound used for modifying the surface of the inorganic filler, R ₃ —Si—OR ′ and R ₃ —Si—NH—Si—R ₃ (R are the same or different aliphatic groups) An alicyclic or aromatic monovalent hydrocarbon group, and the monovalent hydrocarbon group may contain a hetero atom, and R 'is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms). It is at least one organic compound selected from the group.

In this case, the monovalent hydrocarbon group is preferably a group having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, a linear or branched alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group. And a group in which some or all of the hydrogen atoms of these groups are substituted with a halogen atom, a cyano group, or the like. Examples of such an organic compound include CH ₃ — (CH ₂ ) _n —Si (CH ₃ ) ₂ —OH (n is an integer of 0 to 9), CH ₃ — (CH ₂ ) _n —Si (CH ₃ ) _2. -OCH ₃ (n is an integer from 0 to _{9), CH 3 - (CH 2} ) n -Si (CH 3) 2 -NH-Si (CH 3) 2 - (CH 2) n -CH 3 (n is 0 It is particularly preferable that the organic compound is at least one organic compound selected from the group consisting of an integer of ˜9.

  In the present invention, as the organic compound, for example, a silane compound having only one silanol group in the molecule, a silane compound in which only one silanol group is generated in the molecule by hydrolysis, or a silazane compound is used. By suppressing the condensation reaction between groups and using supercritical water or subcritical water as a reaction field, the surface of the thermally conductive inorganic filler is efficiently modified.

  The thermally conductive inorganic filler used in the present invention is preferably made of at least one material selected from the group consisting of metals, metal oxides, metal nitrides, metal carbides, and allotropes of carbon. , Aluminum, silver, copper, metal silicon, alumina, zinc oxide, magnesium oxide, silicon dioxide, aluminum hydroxide, aluminum nitride, boron nitride, silicon carbide, diamond, graphite, carbon nanotube, etc., especially alumina or zinc oxide Is preferred.

  If the average particle size of the thermally conductive inorganic filler is less than 0.1 μm, the viscosity as the thermally conductive silicone composition may be high and the extensibility may be poor, and if it is greater than 300 μm, the thermally conductive silicone composition Since the uniformity of the object may be poor, the range of 0.1 to 300 μm is preferable, and the range of 0.1 to 200 μm is more preferable. The shape of the inorganic filler may be indefinite, spherical or any shape. In addition, an average particle diameter can be calculated | required as a mass average value (or median diameter) in the particle size distribution measurement by a laser beam diffraction method, for example.

[Method for producing organically modified inorganic filler]
The method for producing an organically modified inorganic filler according to the present invention uses the water in a supercritical state or subcritical state as a reaction field, and generates the silanol group by hydrolysis with the above-described thermally conductive inorganic filler. A predetermined organic compound having a functional group is mixed and reacted.

  Here, the high temperature and high pressure conditions for bringing water into a supercritical state or a subcritical state are specifically 200 to 450 ° C, preferably 250 to 450 ° C, more preferably 300 to 400 ° C. If the temperature is less than 200 ° C., the supercritical state or subcritical state necessary for the reaction of the present invention is not achieved, and if it exceeds 450 ° C., the condensation reaction between silanol groups is promoted, which is not suitable. Moreover, a pressure is 10-40 Mpa, Preferably it is 25-40 Mpa, More preferably, it is 30-35 Mpa. If the pressure is less than 10 MPa, the supercritical state or subcritical state necessary for the reaction of the present invention is not achieved, and if it exceeds 40 MPa, the condensation reaction between silanol groups is promoted, which is not suitable.

  Further, the apparatus for realizing the reaction field is not particularly limited as long as it is an apparatus that can achieve high-temperature and high-pressure conditions for bringing water into a supercritical state or a subcritical state, and is a device that is widely known to those skilled in the art. For example, either a batch type apparatus or a flow type apparatus can be used.

As an example of the production method of the present invention, for example, an inorganic filler is dispersed in pure water at an arbitrary concentration into a reaction path through which pure water in a supercritical state or a subcritical state flows at a predetermined temperature and pressure. The slurry and the organic compound having a silanol group or a functional group that hydrolyzes to generate a silanol group are added and mixed, respectively, and the mixture is recovered after cooling. The amount of the organic compound added at this time is an amount necessary for modifying the entire surface of the inorganic filler with an organic substance derived from the organic compound. At this time, an acid and a base for adjusting the pH of the reaction system may be added.
Next, the collected liquid mixture is subjected to solid-liquid separation using a high-speed cooling centrifuge, ethanol is added to the separated solid content, and solid-liquid separation is performed again using a high-speed cooling centrifuge to remove unreacted organic compounds. The target organic modified inorganic filler can be obtained by removing and drying the solid content at a high temperature.

  According to the production method of the present invention, by using water in a supercritical state or a subcritical state as a reaction field, the above-described organic compound having a silanol group or an organic compound having a functional group that is hydrolyzed to generate a silanol group The hydrolyzed product reacts with a functional group such as a hydroxyl group present on the surface of the inorganic filler, thereby chemically bonding the organic compound and the inorganic filler, so that the surface of the inorganic filler is efficiently made of the organic compound. Can be modified.

When the FT-IR (Fourier transform infrared spectroscopic analysis) is measured for the organically modified inorganic filler thus produced, a peak suggesting the presence of an alkyl group is observed in the vicinity of a wave number of 2900 cm ⁻¹ . In addition, when TG-DTA (Thermogravimetry-Differential Thermal Analysis) is measured, a weight loss is hardly observed up to a measurement temperature of about 300 ° C., but a gradual weight loss is observed in a temperature region of 300 ° C. or higher. . From these results, it is inferred that a certain amount of organic compounds are present on the surface of the produced organic modified inorganic filler, and that they are chemically bonded to the surface of the inorganic filler. Moreover, when the organic modified inorganic filler thus prepared is filled into the organopolysiloxane composition, the fluidity can be improved as compared with the case where the same amount of the inorganic filler not subjected to organic modification is filled. Is possible.

[Heat conductive silicone composition]
The heat conductive silicone composition of this invention contains (A) organopolysiloxane and (B) the organic modification inorganic filler of this invention.

  Here, components of the heat conductive silicone composition of the present invention are adjusted according to the purpose, and are used as a heat conductive grease composition and an addition-curing type heat conductive silicone composition.

(Thermal conductive grease composition)
Among the thermally conductive silicone compositions of the present invention, the thermally conductive grease composition includes at least a silicone oil such as dimethylpolysiloxane and methylphenylpolysiloxane and the organic modified inorganic filler of the present invention. Yes, for example, 100 to 1,000 parts by mass of an organically modified inorganic filler is blended with 100 parts by mass of silicone oil.

(Addition-curable thermal conductive silicone composition)
Among the thermally conductive silicone compositions of the present invention, the addition-curable thermal conductive silicone composition is composed of conventionally known components except for the inorganic filler. Examples of the composition are as follows.
(A) Organopolysiloxane having at least two alkenyl groups in the molecule: 100 parts by mass
(B) Organically modified inorganic filler of the present invention: 200 to 3,000 parts by mass,
(C) Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to a silicon atom: 0.1 to 0.1 mol of the number of moles of the alkenyl group derived from the component (a). 5.0 times the amount,
(D) Platinum group metal-based curing catalyst: 0.1 to 500 ppm in terms of platinum group element with respect to component (a).

In this compositional example, the alkenyl group-containing organopolysiloxane of component (a) is generally composed of a repeating main part of the diorganosiloxane unit, but this is a part of the molecular structure. In addition, a branched structure may be included, and a cyclic structure may be used, but a linear diorganopolysiloxane is preferable from the viewpoint of physical properties such as mechanical strength of a cured product. Moreover, kinematic viscosity at 25 ° C. This organopolysiloxane is usually, 10~100,000mm ² / s, particularly preferably from 500~50,000mm ² / s. If the viscosity is too low, the storage stability of the resulting composition will be poor, and if it is too high, the extensibility of the resulting composition may be poor. The kinematic viscosity is a value when using an Ostwald viscometer.

  The organohydrogenpolysiloxane of component (c) is an organohydrogenpolysiloxane having a hydrogen atom (Si—H group) directly bonded to 2 or more, preferably 2 to 100 silicon atoms on average in one molecule. It is a component that acts as a crosslinking agent for component (a). That is, it is added by a hydrosilylation reaction promoted by a platinum group metal-based curing catalyst of component (d) and an alkenyl group in component (a) and an alkenyl group in component (c). Gives a dimensional network structure.

The platinum group metal-based curing catalyst of component (d) is a catalyst for promoting the addition reaction of the alkenyl group derived from component (a) and the Si—H group derived from component (c), and is used for the hydrosilylation reaction. Well-known catalysts are mentioned as the catalyst to be used. Specific examples thereof include platinum group metals such as platinum (including platinum black), rhodium and palladium, H ₂ PtCl ₄ · mH ₂ O, H ₂ PtCl ₆ · mH ₂ O, NaHPtCl ₆ · mH ₂ O. , KaHPtCl ₆ · mH ₂ O, Na ₂ PtCl ₆ · mH ₂ O, K ₂ PtCl ₄ · mH ₂ O, PtCl ₄ · mH ₂ O, PtCl ₂ , Na ₂ HPtCl ₄ · mH ₂ O (where, m is an integer of 0 to 6, preferably 0 or 6.) Chloroplatinic acid, chloroplatinic acid and chloroplatinate, alcohol-modified chloroplatinic acid (US Pat. No. 3,220,972) ), Complex of chloroplatinic acid and olefin (see US Pat. Nos. 3,159,601, 3,159,662, and 3,775,452), platinum black Platinum group gold such as palladium Genus supported on a support such as alumina, silica, carbon, rhodium-olefin complex, chlorotris (triphenylphosphine) rhodium (Wilkinson catalyst), platinum chloride, chloroplatinic acid or chloroplatinate and vinyl group-containing siloxane In particular, a complex with a vinyl group-containing cyclic siloxane may be mentioned.
In addition to the above components, reaction control agents, viscosity modifiers, and the like may be added.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated, this invention is not limited to these Examples.

Alumina AL-47-1 (product name, Showa Denko KK, center particle size 0.9 μm) as inorganic filler, decyldimethylmethoxysilane (CH ₃ — (CH ₂ ) ₉ —Si (CH ₃ ) as organic compound _2- OCH ₃ ) was used to produce organic modified inorganic fillers under the following conditions (Examples 1 to 3).

[Example 1]
3 ml of a slurry in which 30% by mass of alumina is dispersed in pure water in a reaction apparatus (manufactured by ITEC Co., Ltd., MOMI ultra mini) in which pure water in a supercritical state of 380 ° C. and 31 MPa flows at 9 ml / min. / Min and decyldimethylmethoxysilane were mixed and reacted at a flow rate of 0.5 ml / min, and the organically modified alumina slurry was recovered after cooling. Using a high-speed cooling centrifuge (HimacCR22GIII, manufactured by Hitachi Koki Co., Ltd.), solid-liquid separation is performed under conditions of 10,000 rpm, 10 ° C., and 10 minutes, and ethanol is added to the separated solids and washed again. Solid-liquid separation was performed to remove unreacted organic compounds, and the solid content was dried at 150 ° C. for 4 hours to obtain organically modified alumina.

The measurement result of FT-IR of the obtained organic modified alumina is shown in FIG. 1, and the measurement result of TG-DTA is shown in FIG. In FIG. 1, since a peak suggesting the presence of an alkyl group was observed in the vicinity of 2,900 cm ⁻¹ , it is considered that the surface of alumina was modified with a hydrolyzate of decyldimethylmethoxysilane. Further, in FIG. 2, almost no weight reduction was observed up to about 300 ° C., and weight reduction was observed in the temperature range of 300 ° C. or higher. Therefore, in organically modified alumina, a hydrolyzate of decyldimethylmethoxysilane was present on the alumina surface. It is thought to be chemically bonded.

[Example 2]
3 ml of a slurry in which 30% by mass of alumina is dispersed in pure water in a reaction apparatus (manufactured by ITEC Co., Ltd., MOMI ultra-mini) in which pure water in a subcritical state of 340 ° C. and 31 MPa flows at 9 ml / min. / Min and decyldimethylmethoxysilane were mixed and reacted at a flow rate of 0.5 ml / min, and the organically modified alumina slurry was recovered after cooling. By treating this in the same manner as in Example 1, organically modified alumina was obtained.

The measurement result of FT-IR of the obtained organic modified alumina is shown in FIG. 3, and the measurement result of TG-DTA is shown in FIG. In FIG. 3, since a peak suggesting the presence of an alkyl group was observed in the vicinity of 2,900 cm ⁻¹ , it is considered that the surface of alumina was modified with a hydrolyzate of decyldimethylmethoxysilane. Further, in FIG. 4, almost no weight reduction was observed up to about 300 ° C., and weight reduction was observed in the temperature region of 300 ° C. or higher. Therefore, in organically modified alumina, a hydrolyzate of decyldimethylmethoxysilane was present on the alumina surface. It is thought to be chemically bonded.

[Example 3]
3 ml of slurry in which 30% by mass of alumina is dispersed in pure water in a reactor (made by ITEC Co., Ltd., MOMI ultra-mini) in which pure water in a subcritical state of 200 ° C. and 31 MPa flows at 9 ml / min. / Min and decyldimethylmethoxysilane were mixed and reacted at a flow rate of 0.5 ml / min, and the organically modified alumina slurry was recovered after cooling. By treating this in the same manner as in Example 1, organically modified alumina was obtained.

The measurement result of FT-IR of the obtained organic modified alumina is shown in FIG. 5, and the measurement result of TG-DTA is shown in FIG. In FIG. 5, although the intensity was weaker than that in FIGS. 1 and 3, a peak suggesting the presence of an alkyl group was observed in the vicinity of 2,900 cm.sup.- ¹ , so that the surface of alumina was hydrolyzed by decyldimethylmethoxysilane. It is thought that it is modified with a thing. Further, in FIG. 6, almost no weight reduction was observed up to about 300 ° C., and weight reduction was observed in a temperature region of 300 ° C. or higher. Therefore, in organically modified alumina, a hydrolyzate of decyldimethylmethoxysilane was present on the alumina surface. It is thought to be chemically bonded.

Next, 50 parts by mass of the organic modified alumina of Examples 1 to 3 obtained as described above and 10 parts by mass of dimethyl silicone oil KF96-30,000 cs (product name, manufactured by Shin-Etsu Chemical Co., Ltd.) were rotated. -Mixing at room temperature using a revolutionary mixer (product name: Awatori Nertaro, manufactured by Shinky Co., Ltd.), a heat conductive grease was prepared. Further, as Comparative Example 1, the alumina was used as it was without organic modification, and a heat conductive grease was prepared under the same conditions as in Examples 1 to 3 except that .

About the obtained heat conductive grease, using a rotary viscometer (manufactured by Thermo Fisher Scientific Co., Ltd., HAAKE RotoVisco 1), the viscosity (25 ° C.) at a shear rate of 1 s ⁻¹ is measured, and thereby organic The filling property of the modified inorganic filler into silicone oil was evaluated. Moreover, the thermal conductivity of the thermally conductive grease was measured using a thermal conductivity meter (manufactured by Kyoto Electronics Industry Co., Ltd., TPA-501).

Table 1 shows the results of using alumina as the inorganic filler.
Compared to Comparative Example 1, the viscosity of the thermally conductive greases of Examples 1 to 3 is reduced, that is, it can be said that the filling properties of the inorganic filler into the silicone oil are improved in Examples 1 to 3. In particular, in Examples 1 and 2, the effect of improving the filling property was remarkable.

Claims (5)

Using water in a supercritical or subcritical state at a temperature of 200 to 450 ° C. and a pressure of 10 to 40 MPa as a reaction field, an inorganic filler and CH ₃ — (CH ₂ ) _n —Si (CH ₃ ) ₂ —OH (n is an integer of _{9), CH 3 - (CH} 2) n -Si (CH 3) 2 -OCH 3 (n is 9 _{integer), CH 3 - (CH 2} ) n -Si (CH 3) 2 -NH- Organic modified inorganic, characterized by mixing and reacting with at least one organic compound selected from the group consisting of Si (CH ₃ ) ₂ — (CH ₂ ) _n —CH ₃ (n is an integer of 9) A method for producing a filler.   The method for producing an organically modified inorganic filler according to claim 1, wherein the inorganic filler is made of at least one material selected from the group consisting of an allotrope of metal, metal oxide, metal nitride, metal carbide, and carbon. .   The inorganic filler is at least one selected from aluminum, silver, copper, metallic silicon, alumina, zinc oxide, magnesium oxide, silicon dioxide, aluminum hydroxide, aluminum nitride, boron nitride, silicon carbide, diamond, graphite, and carbon nanotube. The manufacturing method of the organic modified inorganic filler of Claim 2 which consists of a material more than a seed | species.   The method for producing an organically modified inorganic filler according to claim 3, wherein the inorganic filler is made of alumina. A thermally conductive silicone composition comprising a step of producing an organic modified inorganic filler by the production method according to any one of claims 1 to 4 and mixing the obtained organic modified inorganic filler with an organopolysiloxane . Manufacturing method .

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