Thermally conductive composition

Abstract

To provide a thermally conductive composition which has high thermal conductivity, and enables production of a cured product having low viscosity immediately after production and adequate hardness.SOLUTION: A thermally conductive composition contains a resin composition, and a thermally conductive filler, wherein the resin composition contains a liquid silicone resin having viscosity at 25°C measured according to JIS Z 8803:2011 of 20 to 200,000,000 mPa s, and a polysiloxane compound having at least one hydroxyl group which is not directly bonded to a silicon atom at a terminal and no vinyl group, a mass ratio [liquid silicone resin / polysiloxane compound] of the liquid silicone resin to the polysiloxane compound is 50 / 50 or more and less than 90 / 10, a content of the thermally conductive filler is 300 to 5,000 pts.mass with respect to 100 pts.mass of the resin composition, and thermal conductivity measured according to ISO22007-2 of the cured product of the thermally conductive composition is 1.0 W / mk or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermally conductive composition. [Background technology]

[0002] In recent years, removing heat from heat-generating bodies has become a problem in a variety of fields. In particular, removing heat from heat-generating electronic components such as electronic devices, personal computers, and automotive engine control units (ECUs) and batteries has become an important issue. Recently, the amount of heat generated by heat-generating components has increased, and as a result, heat-dissipating materials with high thermal conductivity have come to be used as a heat countermeasure.

[0003] Heat dissipation materials include heat dissipation sheets made of elastomers with added thermally conductive fillers as molding materials, and potting materials made of silicone materials with added thermally conductive fillers to increase thermal conductivity as casting materials. These materials have relatively high thermal conductivities, which enable the miniaturization of heat dissipation bodies and the resulting reduction in the size and weight of electronic components, and are therefore widely used. However, with the recent increase in the amount of heat generated by heat-generating bodies, there is a demand for materials with even higher thermal conductivity.

[0004] Various methods have been proposed to solve these problems. For example, Patent Document 1 proposes a multi-part, condensation-curable, thermally conductive silicone adhesive composition that contains a polysiloxane having hydroxyl groups directly bonded to silicon atoms at both ends, a polysiloxane having trialkoxysilyl groups at both ends, at least one condensation catalyst selected from the group consisting of titanates and / or zirconates, and a thermally conductive filler.

[0005] Patent Document 2 proposes a thermally conductive silicone composition and its cured product, which uses an organopolysiloxane as the base polymer and a combination of alumina and aluminum nitride as the thermally conductive filler, the surface of which has been treated with silicone having an alkoxy group at one end. It is shown that this thermally conductive silicone composition has a high thermal conductivity of 5 W / mk, and various heat-dissipating materials are proposed, including addition reaction-curable silicone resins, condensation reaction-curable silicone resins, organic peroxide-curable silicone resins, and greases.

[0006] Furthermore, Patent Document 3 proposes heat dissipation materials including addition reaction curable silicone resins, condensation reaction curable silicone resins, greases, etc., which contain various fillers that have been surface-treated with a silicone resin having an alkoxy group at one end or a silicone resin having alkoxy groups at both ends. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2019-527276 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-210518 [Patent Document 3] US Patent Application Publication No. 2018 / 230172 Summary of the Invention [Problem to be solved by the invention]

[0008] A heat dissipation material is required to have high thermal conductivity and low viscosity immediately after production from the viewpoint of workability during molding and casting. From the same viewpoint, it is also desirable for the material to have a moderate reaction rate and excellent storage stability. Furthermore, the cured product of the heat dissipation material is required to have a moderate hardness, not too hard, so as to minimize the load on the substrate, heating element, etc.

[0009] On the other hand, in the method of Patent Document 1, the thermally conductive filler is pretreated with trialkoxysilane. Pretreatment with trialkoxysilane reduces the viscosity of the multi-part condensation-curable thermally conductive silicone adhesive composition before curing, but because trialkoxysilane also functions as a crosslinking agent, the reaction can proceed abnormally quickly, resulting in an abnormally high hardness of the cured product.

[0010] The method of Patent Document 2 uses a silicone resin with an alkoxy group at one end as a surface treatment agent for a thermally conductive filler, and this silicone resin can be said to be a silane agent in which the alkyl group portion has become a polydimethylsiloxane chain. Using this can reduce the viscosity of the thermally conductive silicone composition, but when a condensation reaction-curing silicone resin is used, it also acts as a crosslinking agent, which can lead to problems such as an abnormally fast reaction, poor storage stability, and an abnormally high hardness of the cured product.

[0011] In the method of Patent Document 3, as in the method of Patent Document 2, a silicone resin having an alkoxy group is used as a surface treatment agent for various fillers (thermally conductive fillers). Therefore, when a condensation reaction curing type silicone resin is used, there are problems such as an abnormally fast reaction, poor storage stability, and an abnormally high hardness of the cured product.

[0012] The present invention has been made in view of the above circumstances, and has an object to provide a thermally conductive composition that has high thermal conductivity, has a low viscosity immediately after production, and is capable of giving a cured product with appropriate hardness. [Means for solving the problem]

[0013] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by the following invention.

[0014] That is, the present disclosure relates to the following: [1] A thermally conductive composition comprising a resin composition and a thermally conductive filler, The resin composition comprises a liquid silicone resin having a viscosity of 20 to 200,000,000 mPa·s at 25°C as measured in accordance with JIS Z8803:2011, and a polysiloxane compound having at least one terminal hydroxyl group that is not directly bonded to a silicon atom and having no vinyl group; a mass ratio of the liquid silicone resin to the polysiloxane compound [the liquid silicone resin / the polysiloxane compound] is 50 / 50 or more and less than 90 / 10; the content of the thermally conductive filler is 300 to 5,000 parts by mass relative to 100 parts by mass of the resin composition; A thermally conductive composition, wherein a cured product of the thermally conductive composition has a thermal conductivity of 1.0 W / mk or more as measured in accordance with ISO 22007-2. [2] The thermally conductive composition according to [1] above, wherein the polysiloxane compound has, at one end of the main chain constituting the polysiloxane compound, two or more hydroxyl groups that are not directly bonded to silicon atoms. [3] The thermally conductive composition according to the above [1] or [2], wherein the polysiloxane compound is represented by the following general formula (1): [ka] (In formula (1), R 1 is an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R 2 ~R 5 are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R 6 and R 8 are each independently a hydrogen atom, a hydroxymethyl group, or a hydroxyethyl group, and R 7 is an alkyl group having 1 to 3 carbon atoms, a hydroxy group, or a phenyl group. n is an integer of 5 to 250, and m is an integer of 1 to 20. 2 and the above R 3 If there are multiple R 2 and R 3may be the same or different from each other.) [4] R 1 The thermally conductive composition according to the above [3], wherein is an alkyl group having 1 to 18 carbon atoms. [5] R 6 and R 8 are each independently a hydroxymethyl group or a hydroxyethyl group. [6] The thermally conductive composition according to any one of the above [1] to [5], wherein the liquid silicone resin is at least one selected from the group consisting of an addition reaction curable silicone resin, a condensation reaction curable silicone resin, and an organic peroxide curable silicone resin. [7] The thermally conductive composition according to any one of the above [1] to [6], wherein the content of the thermally conductive filler is 3,000 parts by mass or less per 100 parts by mass of the resin composition. [8] The thermally conductive composition according to any one of the above [1] to [7], wherein the viscosity of the liquid silicone resin measured at 25°C in accordance with JIS Z8803:2011 is 10,000,000 mPa·s or less. [9] The thermally conductive composition according to any one of the above [1] to [8], which is used for semiconductor packaging.

[10] A method for producing a thermally conductive composition, comprising mixing the thermally conductive composition according to any one of the above [1] to [9] with the liquid silicone, the polysiloxane compound, and the thermally conductive filler.

[11] A method for using a thermally conductive composition, comprising mixing the liquid silicone, the polysiloxane compound, and the thermally conductive filler, and then filling the mixture into a container.

[12] A method for using a thermally conductive composition, comprising filling the liquid silicone, the polysiloxane compound, and the thermally conductive filler separately into a container and then using the composition. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a thermally conductive composition that has high thermal conductivity, has a low viscosity immediately after production, and is capable of giving a cured product with appropriate hardness. DETAILED DESCRIPTION OF THE INVENTION

[0016] The definitions of terms and expressions used in this specification are given below. The viscosity of the liquid silicone resin at 25°C is a value measured in accordance with JIS Z8803:2011 using a rotational viscometer (for example, manufactured by Toki Sangyo Co., Ltd., product name: TVB-10, rotor No. 3) at a rotational speed of 20 rpm. The term "polysiloxane compound having at least one hydroxyl group at its terminal that is not directly bonded to a silicon atom and having no vinyl group" refers to a compound that has at least one hydroxyl group at one terminal of the main chain that constitutes the polysiloxane compound that is not directly bonded to a silicon atom of the polysiloxane compound, and that has no vinyl groups not only at the terminals but also in the main chain that constitutes the polysiloxane compound. The weight average molecular weight (Mw) means the weight average molecular weight measured by gel permeation chromatography (GPC) in terms of polystyrene. The thermal conductivity of the cured product of the thermally conductive composition is a value measured in accordance with ISO22007-2 using a hot disc method thermal property measuring device (manufactured by Kyoto Electronics Manufacturing Co., Ltd., trade name: TPS 2500 S). For preferred ranges (e.g., ranges of content, etc.), the lower and upper limits described in stages can be independently combined. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to form "10 to 60." The viscosity of the thermally conductive composition immediately after production refers to the viscosity up to 5 minutes after production of the thermally conductive composition.

[0017] [Thermal conductive composition] The thermally conductive composition of this embodiment includes a resin composition and a thermally conductive filler. The resin composition includes a liquid silicone resin having a viscosity of 20 to 200,000,000 mPa·s at 25°C as measured in accordance with JIS Z8803:2011, and a polysiloxane compound having at least one terminal hydroxyl group not directly bonded to a silicon atom and no vinyl group, wherein the mass ratio of the liquid silicone resin to the polysiloxane compound [liquid silicone resin / polysiloxane compound] is 50 / 50 or more and less than 90 / 10. The content of the thermally conductive filler is 300 to 5,000 parts by mass per 100 parts by mass of the resin composition. The cured product of the thermally conductive composition has a thermal conductivity of 1.0 W / mK or more as measured in accordance with ISO 22007-2.

[0018] The thermally conductive composition of the present embodiment contains a resin composition that includes a predetermined liquid silicone resin and a predetermined polysiloxane compound, so that the viscosity immediately after production is low and a cured product with appropriate hardness can be obtained. The reason for this is not clear, but is thought to be as follows. It is believed that the hydroxyl groups of the polysiloxane compound, which has at least one hydroxyl group at its terminal that is not directly bonded to a silicon atom, and the hydroxyl groups of the thermally conductive filler interact with each other through intermolecular forces, hydrogen bonds, etc., and as a result, the interaction between the thermally conductive fillers via the hydroxyl groups decreases, resulting in a decrease in the viscosity and hardness of the resin composition.

[0019] <Resin composition> The resin composition of this embodiment contains a liquid silicone resin having a viscosity of 20 to 200,000,000 mPa·s at 25°C as measured in accordance with JIS Z8803:2011, and a polysiloxane compound having at least one terminal hydroxyl group that is not directly bonded to a silicon atom and no vinyl groups. The mass ratio of the liquid silicone resin to the polysiloxane compound in the resin composition [liquid silicone resin / polysiloxane compound] is 50 / 50 or greater and less than 90 / 10.

[0020] The content of the resin composition in the thermally conductive composition of this embodiment is preferably 1.0 mass% or more and 30.0 mass% or less, more preferably 2.0 mass% or more and 20.0 mass% or less, and even more preferably 3 mass% or more and 15 mass% or less, based on the total amount of the thermally conductive composition. When the content of the liquid silicone resin is 1.0 mass% or more, the thermally conductive filler can be kneaded with the liquid resin, and when it is 30.0 mass% or less, high thermal conductivity can be imparted.

[0021] (liquid silicone resin) The liquid silicone resin used in this embodiment has a viscosity of 20 to 200,000,000 mPa·s at 25°C as measured in accordance with JIS Z8803: 2011. Here, the liquid silicone resin refers to a silicone resin that is liquid or has fluidity at room temperature (25°C). If the viscosity is 20 mPa·s or more, the thermal stability is excellent, and if it is 200,000,000 mPa·s or less, a high loading of thermally conductive filler is possible. From these viewpoints, the viscosity is preferably 25 to 20,000,000 mPa·s, more preferably 30 to 10,000,000 mPa·s, and even more preferably 35 to 5,000,000 mPa·s.

[0022] The liquid silicone resin is not particularly limited as long as its viscosity at 25° C. is within the above range, and examples thereof include resins having an organopolysiloxane structure as the main chain. Resins with an organopolysiloxane structure as the main chain include curable silicone resins and non-curable silicone resins. Examples of curable silicone resins include addition reaction curable silicone resins, condensation reaction curable silicone resins, and organic peroxide curable silicone resins. Curable silicone resins filled with thermally conductive fillers can be used as heat-dissipating sheets and heat-dissipating gels. Non-curable silicone resins are organopolysiloxanes whose base polymers do not contain curable functional groups such as alkenyl groups, and are also called non-reactive silicone oils. The most common example is dimethyl silicone oil, which can be used as heat-dissipating grease and heat-dissipating putty when filled with thermally conductive fillers. The silicone oil may be alkyl-modified silicone oil. In this specification, silicone oil refers to a silicone resin that has a relatively low degree of polymerization and is oily at room temperature (25° C.).

[0023] When the liquid silicone resin is a curable silicone resin, it may have a functional group other than the curable functional group.

[0024] In this embodiment, the liquid silicone resin is preferably a curable silicone resin, in order to lower the viscosity immediately after production and to obtain a cured product with a more appropriate hardness, that is, at least one type selected from the group consisting of addition reaction curable silicone resins, condensation reaction curable silicone resins, and organic peroxide curable silicone resins.

[0025] An addition reaction curable silicone resin (also simply referred to as an addition type silicone resin) is a resin that cures when an addition reaction occurs in an alkenyl group contained as a reactive functional group. Examples of addition-type silicone resins include organopolysiloxanes having alkenyl groups, such as vinyl groups, allyl groups, propenyl groups, butenyl groups, pentenyl groups, hexenyl groups, heptenyl groups, and octenyl groups, at the ends and / or side chains of the molecule.

[0026] Condensation reaction curing type silicone resin (also simply referred to as condensation type silicone resin) is a resin that cures by undergoing hydrolysis and causing a condensation reaction, and has hydroxyl groups directly bonded to silicon atoms. Examples of condensation type silicone resins include resins obtained by hydrolysis and condensation reactions of methyltrichlorosilane, methyltrimethoxysilane, methyltriethoxysilane, tetrachlorosilane, tetramethoxysilane, tetraethoxysilane, and the like.

[0027] Organic peroxide-curing silicone resin (also simply referred to as peroxide-type silicone resin) is a resin in which radicals generated from the organic peroxide crosslinking agent abstract hydrogen from the Si-CH3 groups of the peroxide-type silicone resin, and the resulting Si-CH2 radicals bond with each other, causing a crosslinking reaction to occur. Examples of peroxide type silicone resins include organopolysiloxanes having dimethylsiloxane as a main constituent unit.

[0028] In this embodiment, the liquid silicone resin is not particularly limited, but from the viewpoint of ease of control of the reaction rate and improved storage stability, it is preferable that the liquid silicone resin contains a condensation type silicone resin.

[0029] When the resin composition of this embodiment contains at least one liquid silicone resin selected from an addition type silicone resin and a peroxide type silicone resin, the mass ratio of the liquid silicone resin to the polysiloxane compound [liquid silicone resin / polysiloxane compound] is preferably 88 / 12 or less, more preferably 86 / 14 or less, and even more preferably 84 / 16 or less, from the viewpoint of obtaining a cured product with a more appropriate hardness, and is preferably 55 / 45 or more, more preferably 60 / 40 or more, and even more preferably 65 / 35 or more, from the viewpoint of achieving a lower viscosity immediately after production.

[0030] When a condensation type silicone resin is contained as the liquid silicone resin, the mass ratio of the liquid silicone resin to the polysiloxane compound in the resin composition of this embodiment [the liquid silicone resin / the polysiloxane compound] is preferably 85 / 15 or less, more preferably 80 / 20 or less, from the viewpoint of obtaining a cured product with a more appropriate hardness, and is preferably 55 / 45 or more, more preferably 60 / 40 or more, from the viewpoint of achieving a lower viscosity immediately after production.

[0031] The liquid silicone resin may be used alone or in combination of two or more.

[0032] (Polysiloxane compound) The polysiloxane compound of this embodiment has at least one hydroxyl group at its terminal that is not directly bonded to a silicon atom, and does not have a vinyl group. The polysiloxane compound is not particularly limited as long as it has at least one hydroxyl group at its terminal that is not directly bonded to a silicon atom and does not have a vinyl group. However, from the viewpoint of lowering the viscosity immediately after production and obtaining a cured product with more appropriate hardness, it is preferable that the polysiloxane compound has at least two hydroxyl groups at one terminal of the main chain that is not directly bonded to a silicon atom. From the same viewpoint, it is also preferable that the polysiloxane compound does not have a hydroxyl group at the other terminal that is not directly bonded to a silicon atom, other than the terminal that has at least one hydroxyl group that is not directly bonded to a silicon atom. That is, the polysiloxane compound preferably has at least one hydroxyl group that is not directly bonded to a silicon atom at one end of the main chain that constitutes the polysiloxane compound, and has no hydroxyl groups that are not directly bonded to a silicon atom at the other end, and more preferably has at least two hydroxyl groups that are not directly bonded to a silicon atom at one end of the main chain, and has no hydroxyl groups that are not directly bonded to a silicon atom at the other end.

[0033] The weight-average molecular weight (Mw) of the polysiloxane compound is preferably 1,000 or more, more preferably 5,000 or more, and even more preferably 10,000 or more, from the viewpoint of obtaining a cured product with an appropriate hardness, and is preferably 20,000 or less, more preferably 18,000 or less, and even more preferably 17,000 or less, from the viewpoint of keeping the viscosity low immediately after production and of achieving a high loading of thermally conductive filler.

[0034] In one aspect of this embodiment, the polysiloxane compound is preferably a compound represented by the following general formula (1).

[0035] [ka]

[0036] In formula (1), R 1 is an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R 2 ~R 5 are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R 6 and R 8 are each independently a hydrogen atom, a hydroxymethyl group, or a hydroxyethyl group, and R 7 is an alkyl group having 1 to 3 carbon atoms, a hydroxy group, or a phenyl group. n is an integer of 5 to 250, and m is an integer of 1 to 20. 2 and the above R 3 If there are multiple R 2 and R 3 may be the same or different from each other.

[0037] R 1 From the viewpoint of lowering the viscosity immediately after production and obtaining a cured product with more appropriate hardness, the alkyl group is preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, even more preferably an alkyl group having 1 to 5 carbon atoms, and even more preferably a butyl group.

[0038] R 2 ~R 5and are each independently preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, even more preferably an alkyl group having 1 to 5 carbon atoms, and even more preferably a methyl group, from the viewpoint of lowering the viscosity immediately after production and obtaining a cured product with more appropriate hardness.

[0039] R 6 and R 8 and are each independently preferably a hydroxymethyl group or a hydroxyethyl group, more preferably a hydroxymethyl group, from the viewpoint of lowering the viscosity immediately after production and obtaining a cured product with more appropriate hardness.

[0040] R 7 is preferably an alkyl group having 1 to 3 carbon atoms, more preferably an ethyl group, from the viewpoint of lowering the viscosity immediately after production and obtaining a cured product with more appropriate hardness.

[0041] When the liquid silicone resin contains at least one selected from an addition type silicone resin and a condensation type silicone resin, n is preferably 5 to 80, more preferably 8 to 70, from the viewpoint of lowering the viscosity immediately after production and obtaining a cured product with a more appropriate hardness. When the liquid silicone resin contains a peroxide type silicone resin, n is preferably 50 to 250, more preferably 60 to 230, from the viewpoint of lowering the viscosity immediately after production and obtaining a cured product with a more appropriate hardness.

[0042] When the liquid silicone resin contains at least one selected from an addition type silicone resin and a condensation type silicone resin, m is preferably 1 to 20, more preferably 1 to 10, from the viewpoint of lowering the viscosity immediately after production and obtaining a cured product with more appropriate hardness.

[0043] <Thermal conductive filler> The content of the thermally conductive filler in the thermally conductive composition of this embodiment is 300 to 5,000 parts by mass relative to 100 parts by mass of the resin composition. From the viewpoint of obtaining a thermally conductive composition with higher thermal conductivity, the content of the thermally conductive filler in the thermally conductive composition is preferably 500 parts by mass or more, more preferably 600 parts by mass or more, and even more preferably 700 parts by mass or more relative to 100 parts by mass of the resin composition. From the viewpoint of uniformly kneading the thermally conductive filler with the liquid silicone resin, the content is preferably 4,000 parts by mass or less, more preferably 3,000 parts by mass or less, and even more preferably 2,000 parts by mass or less.

[0044] The thermally conductive filler used in this embodiment has the function of transferring heat generated from electronic components etc. to the outside of the system, and examples thereof include metals, metal nitrides, metal oxides, metal carbides, metal hydroxides, etc. The thermally conductive fillers may be used alone or in combination of two or more. From the viewpoint of high thermal conductivity and insulating properties, the thermally conductive filler is preferably a metal nitride or a metal oxide, and a metal nitride and a metal oxide may be used in combination. Examples of metal nitrides include boron nitride, aluminum nitride, silicon nitride, etc. Among these, aluminum nitride is preferred from the viewpoint of high thermal conductivity and high fillability in resin. Examples of metal oxides include zinc oxide, alumina, magnesium oxide, silicon dioxide, iron oxide, etc. Among these, alumina is preferred from the viewpoints of high thermal conductivity, availability of a wide range of particle sizes, and high flexibility in combination with metal nitrides.

[0045] The particle size at 50% cumulative volume in the particle size distribution of the thermally conductive filler as determined by a laser diffraction scattering method (hereinafter referred to as D50) is preferably 0.2 μm or more and 200 μm or less, more preferably 0.5 μm or more and 100 μm or less, and even more preferably 1.0 μm or more and 50 μm or less, from the viewpoints of adjusting the thickness of the thermally conductive material and of ease of handling when kneading the thermally conductive filler into the liquid resin. The D50 of the thermally conductive filler can be measured using a particle size analyzer, specifically by the method described in the examples.

[0046] (aluminum nitride) Known aluminum nitride products such as commercially available products can be used. The aluminum nitride may be obtained by any production method, such as a direct nitriding method in which metallic aluminum powder is directly reacted with nitrogen or ammonia, or a reduction-nitriding method in which alumina is subjected to carbon reduction while being heated in a nitrogen or ammonia atmosphere to simultaneously carry out a nitriding reaction.

[0047] The shape of the aluminum nitride is not particularly limited, and examples thereof include amorphous (crushed), spherical, elliptical, and plate-like (scale-like) shapes. Furthermore, the particle size (D50) at 50% cumulative volume in the particle size distribution of aluminum nitride measured by laser diffraction scattering method is preferably 0.2 μm or more and 200 μm or less, more preferably 10 μm or more and 100 μm or less, and even more preferably 10 μm or more and 50 μm or less.

[0048] From the viewpoint of improving moisture resistance, it is preferable that the aluminum nitride has a silicon-containing oxide coating on its surface. That is, the aluminum nitride is preferably surface-treated. The silicon-containing oxide coating may cover part or all of the surface of the aluminum nitride, but it is preferable that the silicon-containing oxide coating covers the entire surface of the aluminum nitride. Since aluminum nitride has excellent thermal conductivity, aluminum nitride having a silicon-containing oxide coating on the surface (hereinafter also referred to as silicon-containing oxide-coated aluminum nitride) also has excellent thermal conductivity. The "silicon-containing oxide" in the silicon-containing oxide coating and silicon-containing oxide-coated aluminum nitride particles includes silica and oxides containing silicon and aluminum.

[0049] The silicon-containing oxide-coated aluminum nitride has a coverage of the silicon-containing oxide coating covering the surface of the aluminum nitride, as determined by LEIS analysis, of preferably 70% to 100%, more preferably 70% to 95%, even more preferably 72% to 90%, and particularly preferably 74% to 85%. A coverage of 70% to 100% provides superior moisture resistance. A coverage exceeding 95% may result in reduced thermal conductivity.

[0050] The coverage (%) of the silicon-containing oxide film (SiO2) covering the surface of aluminum nitride, as determined by LEIS (Low Energy Ion Scattering) analysis, can be calculated using the following formula: (S Al (AlN)-S Al (AlN+SiO2)) / S Al (AlN) x 100 In the above formula, S Al (AlN) is the area of ​​the Al peak of aluminum nitride, and S Al (AlN+SiO2) is the area of ​​the Al peak of aluminum nitride coated with silicon-containing oxide. The area of ​​the Al peak can be determined by analysis using low-energy ion scattering (LEIS), a measurement method that uses an ion source and a rare gas as a probe. LEIS is an analytical technique that uses rare gases of several keV as incident ions, and is an evaluation method that enables compositional analysis of the outermost surface (Reference: The TRC News 201610-04 (October 2016)).

[0051] A method for forming a silicon-containing oxide coating on the surface of aluminum nitride includes, for example, a first step of covering the surface of aluminum nitride with a siloxane compound having a structure represented by the following formula (2), and a second step of heating the aluminum nitride covered with the siloxane compound at a temperature of 300°C or higher and 800°C or lower.

[0052] [ka]

[0053] In formula (2), R 9 is an alkyl group having four or fewer carbon atoms.

[0054] The structure represented by formula (2) is a hydrogensiloxane structural unit having a Si-H bond. 9 is an alkyl group having 4 or less carbon atoms, that is, a methyl group, an ethyl group, a propyl group, or a butyl group, preferably a methyl group, an ethyl group, an isopropyl group, or a t-butyl group, and more preferably a methyl group.

[0055] The siloxane compound is preferably an oligomer or polymer containing a structure represented by formula (2) as a repeating unit. The siloxane compound may be linear, branched, or cyclic. From the viewpoint of facilitating the formation of a silicon-containing oxide coating film with a uniform thickness, the weight-average molecular weight of the siloxane compound is preferably 100 to 2,000, more preferably 150 to 1,000, and even more preferably 180 to 500. The weight-average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0056] As the siloxane compound, a compound represented by the following formula (3) and / or a compound represented by the following formula (4) are preferably used.

[0057] [ka]

[0058] In formula (3), R 10 and R 11 are each independently a hydrogen atom or a methyl group, and R 10 and R 11 At least one of the following is a hydrogen atom. 1 is an integer of 0 to 10, preferably 1 to 5, and more preferably 1.

[0059] [ka]

[0060] In formula (4), k is an integer of 3 to 6, preferably 3 to 5, and more preferably 4.

[0061] As the siloxane compound, a cyclic hydrogen siloxane oligomer in which n is 4 in formula (4) is particularly preferred from the viewpoint of ease of forming a good silicon-containing oxide coating.

[0062] In the first step, the surface of the aluminum nitride is covered with a siloxane compound containing the structure represented by the formula (2). In the first step, the method is not particularly limited as long as the surface of the aluminum nitride can be covered with a siloxane compound containing the structure represented by formula (2). Examples of the method for the first step include a dry mixing method in which a typical powder mixer is used to add the siloxane compound by spraying while stirring the raw material aluminum nitride, and then dry mixing to coat the surface. Examples of the powder mixer include a Henschel mixer (manufactured by Nippon Coke & Engineering Co., Ltd.), a container-rotating V-blender, a double-cone blender, a ribbon blender with mixing blades, a screw-type blender, a sealed rotary kiln, and stirring with a stirrer in a sealed container using a magnetic coupling. The temperature condition is not particularly limited, but is preferably in the range of 10°C or higher and 200°C or lower, more preferably 20°C or higher and 150°C or lower, and even more preferably 40°C or higher and 100°C or lower.

[0063] Alternatively, a gas-phase adsorption method can be used in which the vapor of the siloxane compound alone or a mixed gas with an inert gas such as nitrogen gas is deposited or evaporated onto the surface of stationary aluminum nitride. The temperature conditions are not particularly limited, but are preferably in the range of 10°C to 200°C, more preferably 20°C to 150°C, and even more preferably 40°C to 100°C. If necessary, the system can also be pressurized or depressurized. The device that can be used in this case is preferably a sealed system that can easily replace the gas within the system, such as a glass container, a desiccator, or a CVD device.

[0064] The amount of the siloxane compound used in the first step is not particularly limited. In the aluminum nitride coated with the siloxane compound obtained in the first step, the amount of the siloxane compound coated is determined by the BET method. 2 / g) to calculate the surface area of ​​1m 2 The coating amount of the siloxane compound is preferably in the range of 0.1 mg to 1.0 mg, more preferably in the range of 0.2 mg to 0.8 mg, and even more preferably in the range of 0.3 mg to 0.6 mg. When the coating amount of the siloxane compound is within the above range, aluminum nitride having a silicon-containing oxide coating with a uniform thickness can be obtained. The specific surface area (m) of the aluminum nitride was determined by the BET method. 2 / g) to calculate the surface area of ​​1m 2 The amount of the siloxane compound coated per unit area was calculated by multiplying the mass difference between aluminum nitride before and after coating with the siloxane compound by the specific surface area (m ) of aluminum nitride determined by the BET method. 2 Surface area (m2) calculated from 2 ) can be found by dividing by

[0065] The specific surface area determined by the BET method can be measured by the nitrogen adsorption BET single-point method using a gas flow method. The evaluation device used can be a Macsorb HM model-1210 manufactured by Mountech.

[0066] In the second step, the aluminum nitride coated with the siloxane compound obtained in the first step is heated at a temperature of 300°C or higher and 850°C or lower. This allows a silicon-containing oxide coating to be formed on the surface of the aluminum nitride. The heating temperature is more preferably 400°C or higher, and even more preferably 500°C or higher.

[0067] The heating time is preferably 30 minutes to 6 hours, more preferably 45 minutes to 4 hours, and even more preferably 1 hour to 2 hours, from the viewpoint of ensuring sufficient reaction time and efficiently forming a good silicon-containing oxide coating. The heat treatment is preferably carried out in an atmosphere containing oxygen gas, for example, in the atmosphere (air).

[0068] After the heat treatment in the second step, the aluminum nitride particles coated with silicon-containing oxide may be partially fused together. In such cases, the particles can be crushed using a general crusher such as a roller mill, hammer mill, jet mill, or ball mill to obtain aluminum nitride coated with silicon-containing oxide that is free from adhesion and aggregation.

[0069] Furthermore, after the second step is completed, the first step and the second step may be carried out in order. That is, the process of carrying out the first step and the second step in order may be repeated.

[0070] (alumina) Alumina has excellent thermal conductivity and moisture resistance. The alumina is preferably α-alumina (α-Al2O3). In addition to α-alumina, γ-alumina, θ-alumina, δ-alumina, etc. may also be included. Known alumina such as commercially available products can be used. Known alumina such as commercially available products are available in a wide variety of particle sizes and shapes, allowing the optimum alumina to be selected, and are also inexpensive. The alumina may be obtained by any method, such as thermal decomposition of ammonium alum, thermal decomposition of ammonium aluminum carbonate, underwater spark discharge of aluminum, gas phase oxidation, and hydrolysis of aluminum alkoxide.

[0071] The shape of the alumina is not particularly limited, and examples thereof include amorphous (crushed), spherical, rounded, and polyhedral shapes. Furthermore, the particle size (D50) at 50% cumulative volume in the particle size distribution of alumina as determined by laser diffraction scattering method is not particularly limited, but is preferably 0.1 μm or more and 50 μm or less.

[0072] For example, in the case of alumina, it is preferable to perform a surface treatment from the viewpoint of obtaining a cured product having a more appropriate hardness. Examples of surface treatment methods include a method of treating the surface of alumina with a silane coupling agent. Examples of silane coupling agents include butyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, and hexadecyltrimethoxysilane. Among these, from the viewpoint of obtaining a cured product having a more appropriate hardness, octyltrimethoxysilane, decyltrimethoxysilane, and hexadecyltrimethoxysilane are preferred, with decyltrimethoxysilane being more preferred. The silane coupling agents may be used alone or in combination of two or more.

[0073] The amount of the silane coupling agent used is preferably 0.01 to 10 parts by mass, more preferably 0.02 to 5 parts by mass, per 100 parts by mass of alumina. By using the silane coupling agent within this range, the surface treatment of the alumina can be performed sufficiently.

[0074] A typical method for treating alumina with a silane coupling agent is to dry mix the raw material alumina by adding the silane coupling agent by spraying while stirring the raw material alumina using a general powder mixer. Examples of the powder mixer include a Henschel mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) and a Spartan Mixer (manufactured by Dalton Co., Ltd.).

[0075] In the treatment of the alumina with the silane coupling agent, after mixing, heat treatment is preferably carried out at a temperature of 100 to 140° C. for 1 to 5 hours, and more preferably at a temperature of 110 to 130° C. for 2 to 4 hours.

[0076] From the viewpoint of increasing thermal conductivity, the total content of aluminum nitride and alumina contained in the thermally conductive filler is preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably 100% by mass.

[0077] The thermally conductive filler may have different particle sizes. For example, by using alumina with a small particle size (e.g., D50 of 0.1 μm to 50 μm) and aluminum nitride with a larger particle size than alumina (e.g., D50 of 10 μm to 100 μm), the amount of thermally conductive powder (mass %) loaded in the thermally conductive composition can be increased, thereby increasing the thermal conductivity of the thermally conductive composition.

[0078] The content of the thermally conductive filler is preferably 70.0% by mass or more and 99.0% by mass or less, more preferably 75.0% by mass or more and 99.0% by mass or less, and even more preferably 80% by mass or more and 98% by mass or less, based on the total amount of the thermally conductive composition of this embodiment. When the content of the thermally conductive powder is 70.0% by mass or more, the thermal conductivity of the thermally conductive composition can be increased, and when it is 99.0% by mass or less, the thermally conductive filler can be kneaded with the liquid silicone resin.

[0079] In addition to the above components, the thermally conductive composition of the present embodiment may contain additives such as crosslinking agents, reaction accelerators, retarders, heat resistance agents, flame retardants, pigments, plasticizers, inorganic ion scavengers, pigments, dyes, and diluents, as needed, within limits that do not impair the effects of the present invention.

[0080] The content of the additive in the thermally conductive composition is preferably 0 parts by mass or more and 200 parts by mass or less relative to 100 parts by mass of the resin composition of this embodiment. The content of the additive in the thermally conductive composition is preferably 0% by mass or more and 20% by mass or less based on the total amount of the thermally conductive composition of this embodiment.

[0081] <Crosslinking agent> The thermally conductive composition of the present embodiment may contain a crosslinking agent from the viewpoint of obtaining a cured product with a more appropriate hardness. When the liquid silicone resin contains an addition type silicone resin, examples of the crosslinking agent include polydimethylhydrosiloxane having a silicon-hydrogen bond, and when the liquid silicone resin contains a condensation type silicone resin, examples of the crosslinking agent include trialkoxysilane, dialkoxysilane, and the like, which are typified by silane coupling agents having two or more alkoxy groups. These may be used alone or in combination of two or more. When the liquid silicone resin in the thermally conductive composition of the present embodiment contains a condensation type silicone resin, it is preferable that the composition contain a crosslinking agent.

[0082] When the liquid silicone resin contains an addition type silicone resin, it is preferable to use an addition type silicone resin represented by the following formula (5) in combination with a crosslinking agent represented by the following formula (6).

[0083] [ka]

[0084] In formula (5), R 12 and R 19 are each independently an alkenyl group, preferably a vinyl group or an allyl group. R 13 ~R 18 are each independently an alkyl group having 1 to 8 carbon atoms or a phenyl group, and are preferably a methyl group. o is an integer from 10 to 1,000.

[0085] [ka]

[0086] In formula (6), R 20 and R 21 are each independently an alkyl group having 1 to 8 carbon atoms or a phenyl group, and more preferably a methyl group. It is preferred that p is 0 to 1,000, q is 0 to 100, and p / q is 0 to 100.

[0087] When the liquid silicone resin contains a condensation type silicone resin, it is preferable to use a condensation type silicone resin represented by the following formula (7) in combination with at least one crosslinking agent selected from the group consisting of tetraalkoxysilane, trialkoxysilane, dialkoxysilane, trialkoxyalkene at both ends, alkyltriacetoxysilane, alkenyltriacetoxysilane, silicones having alkoxy groups at both ends, silicones having an alkoxy group at one end, partial hydrolysates of the above compounds, and two or more hydrolysates different from the above compounds.

[0088] [ka]

[0089] In formula (7), R 22 ~R 27 are each independently an alkyl group having 1 to 8 carbon atoms or a phenyl group, and are preferably a methyl group or a phenyl group. r is between 10 and 500.

[0090] When the liquid silicone resin contains a peroxide type silicone resin, it is preferable to use a liquid silicone resin represented by the following formula (8) in combination with an organic peroxide as a crosslinking agent.

[0091] [ka]

[0092] In formula (8), R 28 and R 35 are each independently an alkyl group having 1 to 8 carbon atoms, an alkenyl group, or a hydroxyl group, preferably an alkenyl group, and more preferably a vinyl group. R 29 ~R 34 is a methyl group or a phenyl group, preferably a methyl group. s is between 600 and 3000.

[0093] Examples of the organic peroxides include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dicumyl peroxide, 2,5-dimethyl-bis(2,5-t-butylperoxy)hexane, di-t-butyl peroxide, t-butyl perbenzoate, and 1,1-bis(t-butylperoxycarboxy)hexane. Among these, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, and o-methylbenzoyl peroxide are preferred from the viewpoint of the possibility of extrusion processing.

[0094] The content of the crosslinking agent in the thermally conductive composition is preferably 0.001% by mass or more and 10% by mass or less, more preferably 0.01% by mass or more and 5% by mass or less, and even more preferably 0.1% by mass or more and 1% by mass or less, relative to the total amount of the thermally conductive composition of this embodiment.

[0095] <Reaction accelerator> The thermally conductive composition of the present embodiment may contain a reaction accelerator. When the liquid silicone resin contains an addition type silicone resin, examples of the reaction accelerator include platinum catalysts, such as chloroplatinic acid, alcohol-modified platinum, and siloxane-modified platinum. When the liquid silicone resin contains a condensation type silicone resin, examples of the reaction accelerator include organometallic compounds, tertiary amine compounds, etc. Examples of organometallic compounds include organotin compounds, organotitanium compounds, organoaluminum compounds, organozirconium compounds, organobismuth compounds, organotungsten compounds, organomolybdenum compounds, organocobaltate compounds, organozinc compounds, organopotassium compounds, and organoiron compounds. When the liquid silicone resin contains a peroxide type silicone resin, examples of the reaction accelerator include an amine compound and an organic cobalt acid. The reaction accelerator may be used alone or in combination of two or more kinds. It is preferable to select a compound and an amount of the reaction accelerator that are appropriate for the reaction mechanism.

[0096] The content of the reaction accelerator in the thermally conductive composition is preferably 0 part by mass or more and 1 part by mass or less relative to 100 parts by mass of the resin composition of this embodiment. The content of the reaction accelerator in the thermally conductive composition is preferably 0% by mass or more and 1% by mass or less based on the total amount of the thermally conductive composition of this embodiment.

[0097] <Retarder> The thermally conductive composition of the present embodiment may include a retarder. When the liquid silicone resin contains an addition type silicone resin, examples of the retarder include acetylene alcohol, etc. Specific examples of acetylene alcohol include 2-methyl-3-butyn-2-ol and ethynylcyclohexanol. When the liquid silicone resin contains a condensation type silicone resin, examples of the retarder include low molecular weight siloxanes having hydroxyl groups at both ends. When the liquid silicone resin contains a peroxide type silicone resin, examples of the retarder include hydroquinones, such as 4-tert-butylphenol. The reaction accelerator may be used alone or in combination of two or more kinds. It is preferable to select a compound and an amount of the reaction accelerator that are appropriate for the reaction mechanism.

[0098] The content of the retarder in the thermally conductive composition is preferably 0 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the resin composition of this embodiment. The content of the retarder in the thermally conductive composition is preferably 0% by mass or more and 1% by mass or less based on the total amount of the thermally conductive composition of this embodiment.

[0099] The viscosity of the thermally conductive composition of this embodiment immediately after production is preferably 50 Pa·s or more and 2,000 Pa·s or less, more preferably 100 Pa·s or more and 1,500 Pa·s or less, and even more preferably 150 Pa·s or more and 1,000 Pa·s or less. The viscosity can be measured using a flow viscometer according to a method in accordance with JIS K7210:2014, and specifically, can be measured by the method described in the examples.

[0100] The consistency of the thermally conductive composition of this embodiment is preferably 250 or more and 400 or less, and more preferably 260 or more and 350 or less. In this specification, consistency is an index showing the softness of a thermally conductive composition, and a larger value indicates a softer thermally conductive composition, i.e., a lower viscosity. The consistency can be measured by a method in accordance with JIS K2220:2013, and specifically, can be measured by the method described in the examples.

[0101] [Method for producing thermally conductive composition] The method for producing the thermally conductive composition is not particularly limited, but the composition can be obtained, for example, by supplying the liquid silicone resin, the polysiloxane, the thermally conductive filler, and various additives, which are blended as needed, all at once or in portions, to a dispersing / dissolving device, and mixing, dissolving, and kneading while heating as needed. Examples of dispersing / dissolving devices include a mortar, a planetary mixer, a rotation / revolution mixer, a kneader, and a roll mill.

[0102] [Cured product of thermally conductive composition] The thermal conductivity of a cured product of the thermally conductive composition of this embodiment, measured in accordance with ISO 22007-2, is 1.0 W / mK or more. From the viewpoint of efficiently removing heat from the heat-generating element, the thermal conductivity is preferably 3 W / mK or more, more preferably 5.0 W / mK or more, and even more preferably 12 W / mK or more. From the viewpoint of viscosity, i.e., coatability and processability, the thermal conductivity is preferably 12 W / mK or less, more preferably 10 W / mK or less, and even more preferably 8 W / mK or less.

[0103] When the thermally conductive composition of this embodiment contains an addition type silicone resin, the cured product of the thermally conductive composition has a C hardness, measured in accordance with the hardness test (type C) of JIS K7312:1996, of preferably 20 to 75, more preferably 25 to 70, and even more preferably 30 to 65. When the C hardness is within the above range, the cured product can have an appropriate hardness. Specifically, the C hardness can be measured by the method described in the examples. The cured product for measuring the C hardness can be prepared by the method described in the Examples containing an addition type silicone resin.

[0104] When the thermally conductive composition of this embodiment contains a condensation type silicone resin or a peroxide type silicone resin, the cured product of the thermally conductive composition has an A hardness, measured in accordance with the hardness test (Type A) of JIS K7312:1996, of preferably 20 to 100, more preferably 25 to 97, and even more preferably 30 to 95. When the A hardness is within the above range, the cured product can have an appropriate hardness. Specifically, the A hardness can be measured by the method described in the examples. In addition, the cured product for measuring the A hardness of the thermally conductive composition containing a condensation type silicone resin can be prepared by the method described in the examples containing the condensation type silicone resin. Furthermore, in the thermally conductive composition containing a peroxide type silicone resin, the cured product for measuring the A hardness can be prepared by the method described in the examples containing the peroxide type silicone resin.

[0105] [Method for producing a cured product of a thermally conductive composition] The cured product of the thermally conductive composition of this embodiment can be obtained by, for example, curing the thermally conductive composition at room temperature (25° C.), by heating, or by moisture. When the liquid silicone resin contains an addition type silicone resin, a cured product can be obtained by reacting the resin at room temperature (25°C) or by heating. When the thermally conductive composition is cured by heating, the heating is preferably carried out at a temperature of 50°C to 150°C for 5 minutes to 2 hours, and more preferably at a temperature of 60°C to 120°C for 10 minutes to 1 hour.

[0106] When the liquid silicone resin contains a condensation type silicone resin, a cured product can be obtained by reacting the resin at room temperature (25°C) or by heating. When the thermally conductive composition is cured by heating, the heating is preferably carried out at a temperature of 50°C to 150°C for 5 minutes to 2 hours, and more preferably at a temperature of 60°C to 120°C for 10 minutes to 1 hour.

[0107] When the liquid silicone resin contains a peroxide-type silicone resin, a cured product can be obtained by reacting the resin at room temperature (25°C) or by heating. When the thermally conductive composition is cured by heating, the composition is preferably cured by first vulcanization at a temperature of 50°C to 150°C, preferably 60°C to 120°C, for 5 minutes to 2 hours, preferably 10 minutes to 1 hour, followed by second vulcanization at a temperature of 100°C to 250°C, preferably 150°C to 230°C, for 1 hour to 10 hours, preferably 2 hours to 6 hours. The first vulcanization is preferably carried out at a pressure of 0.1 to 1.0 MPa.

[0108] [Method of using the thermally conductive composition] In one aspect of this embodiment, the thermally conductive composition of this embodiment may be prepared by mixing the liquid silicone, the polysiloxane compound, and the thermally conductive filler, and then filling the mixture into a container. In another aspect of this embodiment, the thermally conductive composition of this embodiment may be used after the liquid silicone, the polysiloxane compound, and the thermally conductive filler are each individually filled into a container.

[0109] The thermally conductive composition of the present embodiment has a low viscosity immediately after production and can give a cured product with appropriate hardness. Therefore, the composition is suitable for use in heat-generating electronic components such as ECUs and batteries for electronic devices, personal computers, and automobiles, and is particularly suitable for use in semiconductor packages. [Example]

[0110] EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0111] [Raw material compound] Details of the raw material compounds used in Production Examples A-1 to A-4, Production Examples B-1 and B-2, Examples 1 to 14, and Comparative Examples 1 to 20 are as follows.

[0112] (Metal oxide (thermally conductive filler)) Filler A-1 (alumina): AES-12, manufactured by Sumitomo Chemical Co., Ltd., average particle size: 0.5 μm, specific surface area (BET method): 5.8 m 2 / g Filler A-2 (alumina): BAK-5, manufactured by Shanghai Baizu Co., Ltd., average particle size: 5 μm, specific surface area (BET method): 0.36 m 2 / g Filler A-3 (alumina): High-purity alumina AKP-30, manufactured by Sumitomo Chemical Co., Ltd., average particle size: 0.3 μm, specific surface area (BET method): 7.0 m 2 / g Filler A-4 (Alumina) Advanced Alumina AA-03, manufactured by Sumitomo Chemical Co., Ltd., average particle size: 3.0 μm, specific surface area (BET method): 0.5 m 2 / g Filler A-5 (alumina): Alumina AL45H, manufactured by Showa Denko K.K., average particle size: 3.0 μm, specific surface area (BET method): 1.2 m 2 / g Filler A-6 (alumina): Rounded alumina AS-05, manufactured by Showa Denko K.K., average particle size: 45 μm, specific surface area (BET method): 0.1 m 2 / g

[0113] (alkoxysilane) Alkoxysilane 1: KBM-3103C (decyltrimethoxysilane), manufactured by Shin-Etsu Chemical Co., Ltd. Alkoxysilane 2: Dynasylan® 9116 (hexadecyltrimethoxysilane), Evonik Japan Co., Ltd.

[0114] (Metal nitride (thermally conductive filler)) Filler B-1 (aluminum nitride): Toyalnite TFZ-S60X, manufactured by Toyo Aluminum Co., Ltd., average particle size: 55 μm, specific surface area (BET method): 0.1 m 2 / g, ground Filler B-2 (aluminum nitride): Toyalnite TFZ-N15P, manufactured by Toyo Aluminum Co., Ltd., average particle size: 15 μm, specific surface area (BET method): 0.9 m2 / g, ground Filler B-3 (aluminum nitride): FAN-f80-A1, manufactured by Furukawa Electronics Co., Ltd., average particle size: 76 μm, specific surface area (BET method): 0.05 m 2 / g, granular

[0115] (Siloxane compounds) Siloxane compound 1 (D4H): 1,3,5,7-tetramethylcyclotetrasiloxane, Tokyo Chemical Industry Co., Ltd.

[0116] (liquid silicone resin) Addition silicone resin 1: DOWSIL TM EG-3100 (vinyl group-containing dimethyl silicone rubber), manufactured by Dow Toray Co., Ltd., viscosity at 25°C: 320 mPa·s Condensation type silicone resin 1: XP1465 (polysiloxane with hydroxyl groups at both ends), manufactured by JNC Corporation, weight average molecular weight: 14,000, viscosity at 25°C: 230 mPa·s Condensation type silicone resin 2: FM-9915 (polysiloxane with hydroxyl groups at both ends), manufactured by JNC Corporation, weight average molecular weight: 3700, viscosity at 25°C: 63 mPa·s Peroxide-type silicone resin 1: TSE201, manufactured by Momentive Corporation, weight-average molecular weight: 800,000, viscosity at 25°C: 1,000,000 mPa·s or more and 3,000,000 mPa·s or less

[0117] (Polysiloxane compound) Polysiloxane compound 1: a compound represented by the following formula (9) (diol-terminated polysiloxane, n in the following formula (9) is 5 to 250), weight average molecular weight: 5,000, viscosity at 25°C: 80 to 160 mPa s [ka] Polysiloxane compound 2: a compound represented by the above formula (9) (diol-terminated polysiloxane, n in the above formula (9) is 5 to 250), weight average molecular weight: 15,000, viscosity at 25°C: 300 to 700 mPa s Polysiloxane compound 3: KF96-100cs (dimethyl silicone oil, no hydroxyl groups at the terminals), Shin-Etsu Chemical Co., Ltd., weight average molecular weight: 6000, viscosity at 25°C: 96.5 mPa·s Polysiloxane compound 4: KF96-500cs (dimethyl silicone oil, no hydroxyl groups at the terminals), Shin-Etsu Chemical Co., Ltd., weight average molecular weight: 17300, viscosity at 25°C: 96.5 mPa·s

[0118] (Crosslinking agent) Crosslinker 1: TSL8123N (methyltriethoxysilane), manufactured by Momentive Crosslinker 2: HTS-M (hexyltrimethoxysilane), manufactured by JNC Corporation

[0119] (plasticizer) Plasticizer 1: TSF458-50 (polydimethylsiloxane), manufactured by Momentive, viscosity 50 mPa·s

[0120] (catalyst) Catalyst 1: Neostan S-1 (reaction product of alkyltin salt and silicate), manufactured by Nitto Kasei Co., Ltd. Catalyst 2: Orgatix TC-100 (titanium acetylacetonate), Matsumoto Fine Chemical Co., Ltd.

[0121] (organic peroxide) Vulcanizing agent (curing agent): TC-1 (benzoyl peroxide), manufactured by Momentive (additives) KN320 (iron tetroxide, pigment), manufactured by Toda Kogyo Co., Ltd.

[0122] [Surface treatment of thermally conductive filler] The thermally conductive fillers (fillers A-1 to A-4) which are metal oxides and the thermally conductive fillers (fillers B-1 to A-4) which are metal nitrides were subjected to surface treatment. The average particle size and specific surface area of ​​the metal oxide and metal nitride were measured by the following measurement methods. (1) Average particle size The particle size was determined from the particle size at which the cumulative volume reached 50% (50% particle size D50) in the particle size distribution measured using a laser diffraction particle size distribution analyzer (manufactured by Microtrac-Bell Corporation, product name: MT3300EXII). In this specification, the term "volume cumulative particle size D50" refers to the particle size at which the cumulative volume value for a certain particle size distribution is 50%, and is a value calculated from the particle size at which the cumulative volume is 50% (50% particle size D50) in the particle size distribution measured using the laser diffraction particle size distribution analyzer.

[0123] (2) Specific surface area The specific surface area was measured by the BET single-point method using nitrogen adsorption using a specific surface area measuring device (manufactured by Mountec Co., Ltd., trade name: Macsorb MS30).

[0124] <Metal oxide surface treatment> The surface treatment of the metal oxide was carried out in the following Production Examples A-1 to A-4.

[0125] (Manufacturing example A-1) The minimum coverage area of ​​alkoxysilane 1 (298 m) was calculated by multiplying 100 parts by mass of filler A-1 by the specific surface area of ​​filler A-1. 2 The value (1.95 parts by mass) obtained by dividing by the specific surface area of ​​Filler 1 (g) was measured and added as the content of alkoxysilane 1. 5 parts by mass of ethanol was added per 100 parts by mass of Filler A-1. Further, half the amount (0.97 parts by mass) of water obtained by multiplying 100 parts by mass of Filler A-1 by the specific surface area of ​​Filler 1 and dividing by the minimum coverage area of ​​alkoxysilane 1 was added as a chemical. This was added to Filler A-1, and the mixture was stirred and mixed at 1000 rpm for 30 seconds using a rotation-revolution mixer (Thinky Corporation, product name: ARV-310P). This process was repeated four times and then air-dried. Next, the mixture was heated at 120°C for 2 hours in a hot air circulating oven and then cooled to obtain a treated Filler A-1 surface-treated with alkoxysilane 1.

[0126] (Manufacturing example A-2) In Production Example A-1, Filler A-2 was used instead of Filler A-1, and the minimum coverage area of ​​Alkoxysilane 1 (298 m) was calculated by multiplying 100 parts by mass of Filler A-2 by the specific surface area of ​​Filler A-2. 2 The value (0.12 parts by mass) obtained by dividing by the specific surface area of ​​Filler 2 (g) was measured and added as the content of alkoxysilane 1, 5 parts by mass of ethanol was added per 100 parts by mass of Filler A-2, and half the amount (0.06 parts by mass) of the value obtained by multiplying 100 parts by mass of Filler A-2 by the specific surface area of ​​Filler 2 and dividing the result by the minimum coverage area of ​​alkoxysilane 1 was added as a chemical, and treated filler A-2, surface-treated with alkoxysilane 1, was obtained by the same procedure as above, except that this was added to filler A-2.

[0127] (Manufacturing example A-3) The minimum coverage area of ​​alkoxysilane 2 (226 m) was calculated by multiplying 100 parts by mass of filler A-3 by the specific surface area of ​​filler A-3. 2 The value (3.10 parts by mass) obtained by dividing by the specific surface area of ​​Filler A-3 (g) was measured and added as the content of alkoxysilane 2. 5 parts by mass of ethanol was added per 100 parts by mass of Filler A-3. Further, half the amount (1.55 parts by mass) of water obtained by multiplying 100 parts by mass of Filler A-3 by the specific surface area of ​​Filler A-3 and dividing the result by the minimum coverage area of ​​alkoxysilane 2 was added as a chemical. This was added to Filler A-3, and the mixture was stirred and mixed at 1000 rpm for 30 seconds using a rotation-revolution mixer (Thinky Corporation, product name: ARV-310P). This process was repeated four times and then air-dried. Next, the mixture was heated at 120°C for 2 hours in a hot air circulating oven and then cooled to obtain Filler A-3 surface-treated with alkoxysilane 2.

[0128] (Manufacturing example A-4) In Production Example A-3, Filler A-4 was used instead of Filler A-3, and 100 parts by mass of Filler A-4 was multiplied by the specific surface area of ​​Filler A-4 to obtain the minimum coverage area of ​​Alkoxysilane 2 (226 m 2The value (0.22 parts by mass) obtained by dividing by the specific surface area of ​​filler A-4 (g) was measured and added as the content of alkoxysilane 2, 5 parts by mass of ethanol was added per 100 parts by mass of filler A-4, and half the amount (0.11 parts by mass) of the value obtained by multiplying 100 parts by mass of filler A-4 by the specific surface area of ​​filler A-4 and dividing the result by the minimum coverage area of ​​alkoxysilane 2 was added to filler A-4. Treated filler A-4, surface-treated with alkoxysilane 2, was obtained by the same procedure as above, except that this was added to filler A-4.

[0129] <Surface treatment of metal nitride> The surface treatment of the metal nitride was carried out in the following Production Examples B-1 and B-2.

[0130] (Production Examples B-1 and B-2) A 20mm thick acrylic resin vacuum desiccator with internal dimensions of 260mm x 260mm x 100mm and divided into three sections by a perforated partition was used. 200g of fillers B-1 and B-2 were placed on the upper section, evenly spread on an aluminum stainless steel tray, and allowed to stand. Next, 10g of siloxane compound 1 was placed in a glass Petri dish and allowed to stand in the lower section of the vacuum desiccator. The vacuum desiccator was then closed and heated in an oven at 80°C for 30 hours. Safety precautions were taken, such as venting hydrogen gas generated by the reaction through the release valve attached to the vacuum desiccator. Next, the samples were removed from the desiccator and placed in an alumina crucible. The D4H-adhered fillers B-1 and B-2 were heat-treated in air at 700°C for 3 hours to obtain silicon-containing oxide-coated aluminum nitrides, i.e., silicon-containing oxide-coated aluminum nitrides B-1 and B-2.

[0131] (Manufacturing example B-3) A 20mm thick acrylic resin vacuum desiccator with internal dimensions of 260mm x 260mm x 100mm and divided into three sections by a perforated partition was used. 200g of filler B-3 was placed on the top section, evenly spread on an aluminum stainless steel tray, and allowed to stand. Next, 10g of siloxane compound 1 was placed in a glass petri dish and allowed to stand in the bottom section of the vacuum desiccator. The vacuum desiccator was then closed and heated in an oven at 80°C for 30 hours. Safety precautions were taken, such as venting hydrogen gas generated by the reaction through the release valve attached to the vacuum desiccator. Next, the sample was removed from the desiccator and placed in an alumina crucible. The D4H-adhered filler B-3 was heat-treated in air at 800°C for 3 hours to obtain silicon-containing oxide-coated aluminum nitride, silicon-containing oxide-coated aluminum nitride B-3.

[0132] Example 1 85 parts by mass of addition type silicone resin 1, 15 parts by mass of polysiloxane compound 1, 400 parts by mass of treated filler A-1, and 500 parts by mass of treated filler A-2 were added to a planetary centrifugal mixer (Thinky Corporation, product name: ARV-310P) and stirred and mixed at 2000 rpm for 30 seconds under reduced pressure. Subsequently, after cooling to room temperature (25°C), 800 parts by mass of silicon-containing oxide-coated aluminum nitride B-1 were added and stirred and mixed at 2000 rpm for 30 seconds to obtain the thermally conductive composition of Example 1.

[0133] <Examples 2 to 4 and Comparative Examples 1 and 2> Thermally conductive compositions of Examples 2 to 4 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the types and amounts of each component were changed as shown in Table 1.

[0134] <Example 5> 85 parts by mass of condensation type silicone resin 1, 15 parts by mass of polysiloxane compound 1, 520 parts by mass of filler A-5, and 520 parts by mass of filler A-6 were dried in an oven at 100°C for 30 minutes and then stirred at 2000 rpm for 30 seconds using a planetary centrifugal mixer (Thinky Corporation, product name: ARV-310P). After cooling to room temperature (25°C), 4 parts by mass of crosslinker 2 were added, and the mixture was degassed and stirred at 2000 rpm for 30 seconds using a planetary centrifugal mixer. After cooling to room temperature (25°C), 4 parts by mass of catalyst 2 (TC-100) were added, and the mixture was degassed and stirred at 2000 rpm for 30 seconds using a planetary centrifugal mixer to obtain the thermally conductive composition of Example 5.

[0135] <Examples 6 to 15 and Comparative Examples 3 to 9> The thermally conductive compositions of each example and comparative example were obtained in the same manner as in Example 5, except that the types and amounts of each component were changed as shown in Tables 2 to 4.

[0136] Example 16 80 parts by mass of peroxide-type silicone resin 1, 20 parts by mass of polysiloxane compound 2, 200 parts by mass of treated filler A-3, 250 parts by mass of treated filler A-4, 2 parts by mass of additive (iron trioxide), and 5 parts by mass of organic peroxide (TC-1) were added to a planetary centrifugal mixer (Thinky Corporation, product name: ARV-310P) and stirred at 2000 rpm for 30 seconds under reduced pressure. After cooling to room temperature (25°C), 400 parts by mass of silicon-containing oxide-coated aluminum nitride B-2 were added and degassed and stirred at 2000 rpm for 30 seconds to obtain the thermally conductive composition of Example 16.

[0137] <Example 17 and Comparative Examples 10 to 12> The thermally conductive compositions of the examples and comparative examples were obtained in the same manner as in Example 16, except that the types and amounts of each component were changed as shown in Table 5. In addition, in Comparative Example 12, since the composition did not contain a polysiloxane compound having at least one hydroxyl group at its terminal that is not directly bonded to a silicon atom, the viscosity of the composition did not decrease sufficiently, and the thermally conductive filler could not be filled (mixed with the thermally conductive filler).

[0138] [Preparation of test specimens (cured products)] (1) Cured Products of the Thermally Conductive Compositions of Examples 1 to 4 and Comparative Examples 1 and 2 The degassed thermally conductive composition was poured onto a 0.1 mm thick polyester film that had been treated with a fluorine release agent, and then covered with a 0.1 mm thick polyester film to prevent air from getting mixed in. The composition was then formed using a rolling mill, cured at 100°C for 15 minutes, and left to stand at room temperature (23°C) for one day, after which a 2 mm thick sheet was produced. This sheet was cut into 20 mm wide strips, and three of these were stacked to form test specimens (80 mm long, 20 mm wide, 6 mm thick) for each Example and Comparative Example.

[0139] (2) Cured Products of the Thermally Conductive Compositions of Examples 5 to 15 and Comparative Examples 3 to 9 A 0.1 mm thick polyester film that had been subjected to a fluorine release treatment was placed in a mold with a diameter of 45 mm and a thickness of 6 mm. The degassed thermally conductive composition was poured into it without trapping any air, and the surface was smoothed with a spatula. After that, the composition was left in a thermostatic chamber at a temperature of 23±2°C and a humidity of 50±10% RH for one week to obtain test pieces (diameter 45 mm, thickness 6 mm) for each example and comparative example.

[0140] (3) Cured Products of the Thermally Conductive Compositions of Examples 16 to 17 and Comparative Examples 10 to 12 A 0.1 mm thick polyester film that had been treated with a fluorine release agent was placed in a mold with a diameter of 45 mm and a thickness of 6 mm. The degassed thermally conductive composition was poured into the mold without allowing air to enter, and a 0.1 mm thick polyester film was then placed on top without allowing air to enter. The resulting mixture was sandwiched between aluminum plates and subjected to primary vulcanization at 120°C for 30 minutes under 0.5 MPa in a press, followed by secondary vulcanization at 200°C for 4 hours in a hot air circulating oven, to obtain test specimens (45 mm diameter, 6 mm thick) for each of the Examples and Comparative Examples.

[0141] [Measurement evaluation] The properties of the thermally conductive compositions obtained in each of the examples and comparative examples, and test pieces of the cured products thereof, were measured under the following measurement conditions. The results are shown in Tables 1 to 5.

[0142] (1) Viscosity The viscosity of the thermally conductive composition immediately after production (~5 minutes after production) was measured in accordance with JIS K7210:2014 using a flow viscometer (GFT-100EX, manufactured by Shimadzu Corporation) under conditions of a temperature of 30°C, a die hole diameter of 1.0 mm, and a test force of 40 (weight of 7.8 kg).

[0143] (2)Hardness For the test pieces that were cured products of the thermally conductive compositions obtained in Examples 1 to 4 and Comparative Examples 1 and 2, the Asker C hardness was measured using a rubber hardness tester (Kobunshi Keiki Co., Ltd., product name: Asker Rubber Hardness Tester Type C) in accordance with JIS K7312:1996. For the test pieces which were cured products of the thermally conductive compositions obtained in Examples 5 to 17 and Comparative Examples 3 to 12, the Asker A hardness was measured using a rubber hardness tester (manufactured by Kobunshi Keiki Co., Ltd., product name: Asker Rubber Hardness Tester Type A) in accordance with JIS K7312:1996.

[0144] (3) Thermal conductivity The thermal conductivity of the test piece was measured using a hot disk method thermophysical property measuring device (manufactured by Kyoto Electronics Manufacturing Co., Ltd., trade name: TPS 2500 S) in accordance with ISO22007-2.

[0145] (4) Tuck-free time A 0.1 mm thick polyester film that had been treated with a fluorine release agent was prepared and placed in a mold with a diameter of 45 mm and a thickness of 6 mm. The degassed thermally conductive composition was poured into it without trapping any air, and the surface was smoothed with a spatula. The film was then placed in a thermostatic chamber at a temperature of 23±2°C and a humidity of 50±10%RH, and the time until the surface lost its tack was measured every 15 minutes or every 5 minutes. The tack-free time is an index of quick drying, and the longer the tack-free time, the slower the reaction rate.

[0146] (5) Consistency The consistency of the thermally conductive resin composition was measured by the ¼ cone penetration as defined in JIS K2220:2013 using an automatic penetration tester (RPM-101, manufactured by Rigo Co., Ltd.).

[0147] [Table 1]

[0148] [Table 2]

[0149] [Table 3]

[0150] [Table 4]

[0151] [Table 5]

[0152] A comparison between the Examples and Comparative Examples shows that when the thermally conductive composition contains a polysiloxane compound having a hydroxyl group at its terminal, it is possible to obtain a cured product that has low viscosity immediately after production and appropriate hardness.

Claims

1. A thermally conductive composition comprising a resin composition and a thermally conductive filler, The resin composition contains a liquid silicone resin (excluding the compound represented by general formula (1)) having a viscosity of 20 to 200,000,000 mPa s at 25°C as measured in accordance with JIS Z8803:2011, a polysiloxane compound represented by the following general formula (1), and an organic peroxide as a crosslinking agent: The liquid silicone resin contains an organic peroxide-curable silicone resin represented by the following formula (8): a mass ratio of the liquid silicone resin to the polysiloxane compound [the liquid silicone resin / the polysiloxane compound] is 50 / 50 or more and less than 90 / 10, the content of the thermally conductive filler is 300 to 5,000 parts by mass relative to 100 parts by mass of the resin composition; A thermally conductive composition, wherein a cured product of the thermally conductive composition has a thermal conductivity of 1.0 W / mK or more as measured in accordance with ISO 22007-2. 【Chemistry 1】 In formula (1), R 1 is an alkyl group having 1 to 18 carbon atoms or a phenyl group; R 2 to R 5 are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group; R 6 and R 8 are each independently a hydroxymethyl group or a hydroxyethyl group; and R 7 is an alkyl group having 1 to 3 carbon atoms, a hydroxy group, or a phenyl group. n is 5 to 250, and m is 1 to 20. When a plurality of R 2s and R 3s are present, the plurality of R 2s and R 3s may be the same or different from each other. In formula (8), R 28 and R 35 are each independently an alkyl group having 1 to 8 carbon atoms, an alkenyl group, or a hydroxyl group. R 29 to R 34 are each a methyl group or a phenyl group. s is 600 to 3000.

2. The R １ The thermally conductive composition according to claim 1, wherein is an alkyl group having 1 to 18 carbon atoms.

3. The thermally conductive composition according to claim 1, wherein R 28 and R 35 are alkenyl groups.

4. The thermally conductive composition according to claim 1, wherein R 29 to R 34 are methyl groups.

5. The thermally conductive composition described in claim 1, wherein the organic peroxide is at least one selected from the group consisting of benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, and o-methylbenzoyl peroxide.

6. The thermally conductive composition according to claim 1 , wherein the content of the thermally conductive filler is 3,000 parts by mass or less relative to 100 parts by mass of the resin composition.

7. 2. The thermally conductive composition according to claim 1, wherein the liquid silicone resin has a viscosity at 25°C measured in accordance with JIS Z8803:2011 of 10,000,000 mPa·s or less.

8. The thermally conductive composition according to any one of claims 1 to 7, which is used for semiconductor packaging.

9. A method for producing a thermally conductive composition, comprising mixing the thermally conductive composition according to any one of claims 1 to 7 with the liquid silicone, the polysiloxane compound, and the thermally conductive filler.

10. 8. A method for using the thermally conductive composition according to claim 1, wherein the liquid silicone, the polysiloxane compound, and the thermally conductive filler are mixed together, and then the mixture is filled into a container for use.

11. 8. A method for using the thermally conductive composition according to claim 1, wherein the liquid silicone, the polysiloxane compound, and the thermally conductive filler are each filled separately into a container and then used.

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