Thermosoftening thermally conductive silicone composition and cured product

Abstract

The present invention provides a thermosoftening thermally conductive silicone composition which contains: (A) a phenyl-modified organopolysiloxane that has two or more alkenyl groups in each molecule and has a kinematic viscosity of 100-100,000 mm2 / s at 25°C, while containing no T unit; (B) an organohydrogenpolysiloxane that has at least two hydrosilyl groups at molecular chain terminals; (C) one or more compounds that are selected from among an organopolysiloxane having a hydrolyzable functional group and an alkoxysilane compound represented by a specific formula; (D) one or more thermally conductive fillers that are selected from the group consisting of a metal, a metal oxide, a metal hydroxide, and a metal nitride; and (E) a platinum group metal catalyst. The present invention thereby provides: a thermosoftening thermally conductive silicone composition which does not contain a thermoplastic silicone resin having a T unit and which has excellent thermosoftening properties; and a cured product. The present invention also provides a cured product of a thermosoftening thermally conductive silicone composition, the cured product having excellent reworkability.

Description

Thermosoftening, thermally conductive silicone composition and cured product

[0001] The present invention relates to a thermosoftening, thermally conductive silicone composition and a cured product.

[0002] Electronic components such as CPUs, which are highly integrated circuits, experience a significant decrease in performance due to heat generation during use. To solve this problem, heat dissipation materials are used to improve heat transfer efficiency by being introduced into the air layer between the heat-generating and cooling parts. Among these, silicone heat dissipation materials are widely used in various fields due to their high heat resistance, weather resistance, and electrical insulation properties derived from silicone. Furthermore, in recent years, as electronic devices have become smaller and more highly integrated, it has become important to cool the generated heat more efficiently, thus requiring heat dissipation materials with higher thermal conductivity.

[0003] In recent years, phase-change heat dissipation materials (phase-change materials) that are solid at room temperature and soften when heated have been proposed. Phase-change materials are mounted between electronic components and heat sinks, and when heated, the softened phase-change material conforms to the warping and unevenness of the electronic components and heat sink, significantly reducing the interfacial contact thermal resistance and improving heat dissipation characteristics.

[0004] It is known that a common phase-change material uses α-olefin resins or paraffin waxes as resin components, and by compounding these with a thermally conductive filler, the phase-change function is achieved (Patent Document 1). However, these organic compound-based phase-change materials have problems such as poor heat resistance and flame retardancy.

[0005] On the other hand, silicone is known as a material with excellent heat resistance and flame retardancy, and many phase-change materials using silicone as a resin component have been reported. In fact, it is known that heat dissipation members consisting of thermoplastic silicone resin and a thermally conductive filler have improved heat resistance and flame retardancy (Patent Document 2). The resin component of the above-mentioned silicone-based phase-change material uses thermoplastic silicone resin having a T unit. However, because thermoplastic silicone resin is highly tacky, conventional silicone-based phase-change materials have the problem of poor reworkability. In recent years, there has been a demand for heat dissipation materials that can be easily attached and detached from the viewpoint of workability and handling.

[0006] Japanese Patent Publication No. 2000-509209, International Publication No. 2002 / 091465

[0007] The present invention aims to provide a thermoplastic, thermally conductive silicone composition and cured product with excellent thermal softening properties, which does not contain a thermoplastic silicone resin having T units. Furthermore, it aims to provide a cured product of a thermoplastic, thermally conductive silicone composition with excellent reworkability.

[0008] To solve the above problems, the present invention provides a thermosoftening, thermally conductive silicone composition comprising the following components (A) to (E): (A) Having two or more alkenyl groups in one molecule and having a kinematic viscosity of 100 to 100,000 mm at 25°C ２ / s and R' １ SiO ３／２ Phenyl-modified organopolysiloxane (in the formula R') that does not contain units (T units) １ (A) is a substituted or unsubstituted monovalent hydrocarbon group. (A): 100 parts by mass, (B) an organohydrogenpolysiloxane having at least two hydrosilyl groups at the molecular chain ends: in an amount such that the number of moles of hydrosilyl groups in component (B) is 0.1 to 3 moles per mole of alkenyl groups in component (A), (C) one or more selected from organopolysiloxanes having hydrolyzable functional groups and alkoxysilane compounds represented by the following general formula (2): 10 to 1,000 parts by mass, R ３ｂ R ４ ｃ Si(OR ５ ) ４－ｂ－ｃ (2) (In the formula, R ３ is independently an alkyl group having 6 to 15 carbon atoms, R ４ is independently a monovalent hydrocarbon group having 1 to 15 carbon atoms, R ５ is independently an alkyl group having 1 to 6 carbon atoms, b is an integer of 1 to 3, c is an integer of 0 to 2, provided that b + c is an integer of 1 to 3.) (D) One or more kinds of thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, and metal nitrides: an amount that becomes 10 to 97% by mass based on the whole composition, and (E) a platinum group metal catalyst: 0.01 to 1,000 ppm on a mass basis in terms of platinum group metal atoms with respect to the mass of the component (A).

[0009] For such a thermoplastic thermally conductive silicone composition, a thermoplastic thermally conductive silicone composition excellent in thermoplasticity and not containing a thermoplastic silicone resin having a T unit can be obtained. Further, a cured product of such a thermoplastic thermally conductive silicone composition is excellent in reworkability.

[0010] Further, in the present invention, it is preferable that the organopolysiloxane having a hydrolyzable functional group as the component (C) is represented by the following general formula (1). (In the formula, R １ is independently an aromatic hydrocarbon group having 6 to 10 carbon atoms or independently an alkyl group having 1 to 10 carbon atoms, R ２ is an alkyl group having 1 to 4 carbon atoms. a is 2 or 3, and n is an integer of 2 ≤ n ≤ 60. However, it contains 1% or more of an aromatic hydrocarbon group having 6 to 10 carbon atoms.)

[0011] Such a structure is preferable as the organopolysiloxane having a hydrolyzable functional group.

[0012] Further, in the present invention, it is preferable that the thermoplastic thermally conductive silicone composition further contains a non-reactive phenyl-modified organopolysiloxane as the component (F).

[0013] The thermosoftening, thermally conductive silicone composition of the present invention may contain such components.

[0014] In this case, it is preferable that the (F) component is contained in an amount of 1 to 500 parts by mass per 100 parts by mass of the (A) component.

[0015] With this amount of component (F), the viscosity of the composition and its cured product can be reduced without reducing processability.

[0016] Furthermore, in the present invention, it is preferable that the viscosity of the thermosoftening, thermally conductive silicone composition at 80°C is 50% or less of the viscosity at 40°C, i.e., (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.5.

[0017] Such a thermosoftening, thermally conductive silicone composition has sufficient thermosoftening properties.

[0018] Furthermore, the present invention provides a heat-softening, heat-conducting silicone cured product, which is a heat-softening, heat-conducting silicone composition described above that has been cured.

[0019] With such a thermosoftening, thermally conductive silicone cured product, it is possible to obtain a thermosoftening, thermally conductive silicone cured product with excellent thermosoftening properties that does not contain thermoplastic silicone resin having T units. Furthermore, it is possible to obtain a thermosoftening, thermally conductive silicone cured product with excellent reworkability.

[0020] In this case, it is preferable that the viscosity of the heat-softening, heat-conductive silicone cured product at 80°C is 70% or less of the viscosity at 40°C, i.e., (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.7.

[0021] Such a heat-softening, heat-conductive silicone cured product has sufficient heat-softening properties.

[0022] As described above, the thermosoftening, thermally conductive silicone composition and cured product of the present invention exhibit excellent thermosoftening properties. Furthermore, the cured product of the thermosoftening, thermally conductive silicone composition of the present invention exhibits excellent reworkability.

[0023] As described above, there was a need for the development of a thermoplastic, thermally conductive silicone composition and cured product with excellent thermal softening properties that does not contain thermoplastic silicone resin having T units.

[0024] As a result of diligent research into the above problems, the inventors of the present invention have found that a thermo-softening, thermally conductive silicone composition containing the following components (A) to (E) can solve the above problems, and have completed the present invention.

[0025] In other words, the present invention is a thermosoftening, thermally conductive silicone composition comprising the following components (A) to (E): (A) Having two or more alkenyl groups in one molecule and having a kinematic viscosity of 100 to 100,000 mm at 25°C ２ / s and R' １ SiO ３／２ Phenyl-modified organopolysiloxane (in the formula R') that does not contain units (T units) １ (A) is a substituted or unsubstituted monovalent hydrocarbon group. (A): 100 parts by mass, (B) an organohydrogenpolysiloxane having at least two hydrosilyl groups at the molecular chain ends: in an amount such that the number of moles of hydrosilyl groups in component (B) is 0.1 to 3 moles per mole of alkenyl groups in component (A), (C) one or more selected from organopolysiloxanes having hydrolyzable functional groups and alkoxysilane compounds represented by the following general formula (2): 10 to 1,000 parts by mass, R ３ ｂ R ４ ｃ Si ( OR ５ ) ４－ｂ－ｃ (2) (wherein, R ３ R is an alkyl group having 6 to 15 carbon atoms, ４ R is an independent monovalent hydrocarbon group having 1 to 15 carbon atoms. ５(A) is an alkyl group having 1 to 6 carbon atoms independently, b is an integer from 1 to 3, c is an integer from 0 to 2, except that b + c is an integer from 1 to 3. (D) One or more thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, and metal nitrides: in an amount of 10 to 97% by mass of the whole composition, and (E) Platinum group metal catalyst: 0.01 to 1,000 ppm on a mass basis converted to platinum group metal atoms relative to the mass of component (A).

[0026] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0027] [Thermo-softening, thermally conductive silicone composition] The present invention is a thermo-softening, thermally conductive silicone composition comprising the following components (A) to (E). It may also contain the following component (F) and other components as needed. Each component will be described in detail below.

[0028] [(A) Phenyl-modified organopolysiloxane] Component (A) has two or more alkenyl groups in the molecule, preferably 2 to 10, more preferably 2 to 5, and has a kinematic viscosity of 100 to 100,000 mm at 25°C. ２ It is a phenyl-modified organopolysiloxane that is / s, and R' １ SiO ３／２ Does not contain units (T units) (R' in the formula) １ (This is a substituted or unsubstituted monovalent hydrocarbon group.)

[0029] The main chain is preferably composed of diorganosiloxane units, R' １ SiO ３／２ Units (T units) are not included (R' in the formula) １ (The group is a substituted or unsubstituted monovalent hydrocarbon group.) Preferably, it is a linear organopolysiloxane.

[0030] The alkenyl group is preferably an alkenyl group having 2 to 8 carbon atoms, and more preferably an alkenyl group having 2 to 6 carbon atoms. Examples include vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, and octenyl group. The vinyl group is particularly preferred. The alkenyl group may be bonded to a silicon atom at the end of the molecular chain, to a silicon atom in the middle of the molecular chain, or to both.

[0031] Furthermore, the phenyl-modified organopolysiloxane of component (A) preferably has 0.0000001 to 0.005 mol / g, particularly 0.00001 to 0.005 mol / g of alkenyl groups per molecule.

[0032] Furthermore, component (A) has a phenyl group. The amount of phenyl groups in one molecule is preferably 5 to 100%, and more preferably 20 to 100%, of the siloxane units containing a phenyl group per total siloxane unit. If the amount of phenyl groups in one molecule is within the above range relative to the total siloxane units, the thermal softening properties of the thermosoftening thermal conductive silicone composition and the cured product will be good.

[0033] Furthermore, the phenyl group may be contained in either the terminal or side chain, but it is preferable that the phenyl group be contained only in the side chain.

[0034] Furthermore, from the viewpoint of viscosity, groups other than the alkenyl group and phenyl group are preferably alkyl groups having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 8 carbon atoms. Examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, etc. Some of these alkyl groups may be used in which some of the hydrogen atoms are substituted with halogen atoms. Methyl groups are particularly preferred as alkyl groups.

[0035] Furthermore, the phenyl-modified organopolysiloxane of component (A) has a kinematic viscosity of 100 to 100,000 mm² at 25°C. ２The kinematic viscosity is / s. In this invention, the kinematic viscosity is the value measured by an Ostwald viscometer as described in JIS Z8803:2011. The kinematic viscosity is preferably 300 to 20,000 mm². ２ / s, and more preferably 500 to 10,000 mm ２ It is / s. The kinematic viscosity is 100 mm ２ If the value is less than / s, the phenyl modification rate becomes too small, which is undesirable. Also, if the kinematic viscosity is 100,000 mmHg ２ If the value exceeds / s, it becomes difficult to handle the thermo-softening, thermally conductive silicone composition, which is undesirable.

[0036] The phenyl-modified organopolysiloxanes described above may be used alone or in combination of two or more types.

[0037] [(B) Organohydrogenpolysiloxane] Component (B) is an organohydrogenpolysiloxane having at least two hydrosilyl groups at the ends of its molecular chain. Preferably, it is an organohydrogenpolysiloxane having two hydrosilyl groups at the ends of its molecular chain and preferably 0 to 10, more preferably 0 to 4, hydrosilyl groups in its side chain. Preferably, there is one hydrosilyl group at each of the two ends of the molecular chain.

[0038] Component (B) can be used if it can undergo an addition reaction with the alkenyl group of component (A) in the presence of the platinum group metal catalyst (E) described later to form a sylalkylene structure.

[0039] (B) The molecular structure of component (B) is not particularly limited as long as it has the above properties, and examples include a linear structure, a branched chain structure, or a linear structure having a partially branched or cyclic structure. A linear structure is preferred.

[0040] Component (B) has a kinematic viscosity at 25°C, preferably 1 to 1,000 mm². ２ / s, more preferably 10-100 mm ２ The kinematic viscosity is 1 mm². ２ If the temperature is above / s, the physical properties of the thermosoftening, thermally conductive silicone composition will be good, and 1,000 mm ２If the value is less than or equal to / s, the extensibility of the thermosoftening, thermally conductive silicone composition will be sufficient.

[0041] The organic group bonded to the silicon atom of component (B) preferably includes a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms, and preferably does not include groups that have hydrosilylation reactivity, such as alkenyl groups or alkynyl groups.

[0042] Furthermore, groups other than the monovalent aromatic hydrocarbon group are preferably alkyl groups, more preferably alkyl groups having 1 to 12 carbon atoms, and more preferably alkyl groups having 1 to 10 carbon atoms. Examples include methyl groups, ethyl groups, propyl groups, butyl groups, hexyl groups, and dodecyl groups. It is also possible to use alkyl groups in which some of the hydrogen atoms are substituted with halogen atoms. Among these, the methyl group is preferred.

[0043] (B) Component may be used alone or in combination of two or more types.

[0044] The amount of component (B) is such that the number of moles of hydrosilyl groups in component (B) is 0.1 to 3 moles, preferably 0.5 to 3 moles, and more preferably 0.7 to 2 moles, per mole of alkenyl groups in component (A). If the amount of component (B) is less than the lower limit, the addition reaction will not proceed sufficiently, and crosslinking will be insufficient. If it exceeds the upper limit, the crosslinking structure may become non-uniform, or the long-term stability of the heat-softening, heat-conductive silicone composition may deteriorate.

[0045] [(C) Compounds having hydrolyzable functional groups] Component (C) is one or more selected from organopolysiloxanes having hydrolyzable functional groups and alkoxysilane compounds represented by the following general formula (2).

[0046] It is preferable that the organopolysiloxane having a hydrolyzable functional group of component (C) is represented by the following general formula (1). (In the formula, R １ R is independently an aromatic hydrocarbon group having 6 to 10 carbon atoms, or independently an alkyl group having 1 to 10 carbon atoms. ２(where a is an alkyl group having 1 to 4 carbon atoms; a is 2 or 3, and n is an integer between 2 and 60; provided that it contains 1% or more of an aromatic hydrocarbon group having 6 to 10 carbon atoms.)

[0047] In the above general formula (1), R １ R is independently a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms, or independently an alkyl group having 1 to 10 carbon atoms. １ Specific examples include aryl groups such as phenyl, tolyl, xyl, and mesityl groups, and alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, octyl, nonyl, and decyl groups. Among these, phenyl and methyl groups are preferred from the viewpoint of ease of synthesis.

[0048] In the above general formula (1), R ２ R is an alkyl group having 1 to 4 carbon atoms, preferably 1 to 2 carbon atoms. ２ Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, and tert-butyl groups. Among these, methyl and ethyl groups are particularly preferred from the viewpoint of hydrolysis of organopolysiloxanes having hydrolyzable functional groups. In addition, in the above general formula (1), a is an integer of 2 or 3, and is preferably 3.

[0049] In the above general formula (1), n ​​is an integer between 2 ≤ n ≤ 60, preferably 9 ≤ n ≤ 30, and more preferably 12 ≤ n ≤ 18. Within this range, it is preferable because it exhibits good compatibility with component (A), which is a phenyl-modified organopolysiloxane, and component (B), which is an organohydrogenpolysiloxane.

[0050] In the above general formula (1), the content of aromatic hydrocarbon groups having 6 to 10 carbon atoms is 1% or more, preferably 3% or more.

[0051] Alkoxysilane compounds are represented by the following general formula (2). ３ ｂ R ４ ｃ Si ( OR ５ ) ４－ｂ－ｃ (2) (wherein, R３ R is an alkyl group having 6 to 15 carbon atoms, ４ R is an independent monovalent hydrocarbon group having 1 to 15 carbon atoms. ５ (where b is an alkyl group having 1 to 6 carbon atoms, b is an integer from 1 to 3, c is an integer from 0 to 2, and b + c is an integer from 1 to 3.)

[0052] In the above general formula (2), R ３ Examples of alkyl groups having 6 to 15 carbon atoms represented by this R include hexyl, octyl, nonyl, decyl, dodecyl, and tetradecyl groups. ３ If the number of carbon atoms in the alkyl group represented by is outside the range of 6 to 15, the wettability of component (A) will be insufficient, resulting in poor handling.

[0053] In the above general formula (2), R ４ Examples of monovalent hydrocarbon groups represented by include alkyl groups having 1 to 5 carbon atoms, preferably 1 to 3; aryl groups having 6 to 15 carbon atoms, preferably 6 to 12; and aralkyl groups having 7 to 15 carbon atoms, preferably 7 to 12. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, and neopentyl groups. Examples of aryl groups include phenyl, tolyl, xylyl, naphthyl, and biphenylyl groups. Examples of aralkyl groups include benzyl, phenylethyl, phenylpropyl, and methylbenzyl groups. Among these, methyl, ethyl, propyl, and phenyl groups are preferred.

[0054] In the above general formula (2), R ５ Examples of C1-C6 alkyl groups represented by include methyl, ethyl, propyl, butyl, and hexyl groups.

[0055] The amount of component (C) is 10 to 1,000 parts by mass, preferably 10 to 500 parts by mass, per 100 parts by mass of component (A). If the amount is less than 10 parts by mass, the phase inversion properties will be significantly reduced, and if it exceeds 1,000 parts by mass, the processability will be poor.

[0056] [(D) Thermally conductive filler] Component (D) is one or more thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, and metal nitrides. Examples include aluminum, silver, alumina (aluminum oxide), zinc oxide, magnesium oxide, silicon dioxide, cerium oxide, iron oxide, aluminum hydroxide, cerium hydroxide, aluminum nitride, boron nitride, etc. These can be used individually or in appropriate combinations of two or more, and it is preferable that they are a combination of large particle components and small particle components.

[0057] If the average particle size of the large particle components is 0.1 μm or larger, the viscosity of the resulting composition will not become too high, and the processability will not decrease. Furthermore, if it is 100 μm or less, the resulting composition will not become non-uniform, and there is no risk of oil bleeding or a decrease in compressibility. Therefore, a range of 0.1 to 100 μm is preferred, and a range of 1 to 75 μm is more preferred.

[0058] Furthermore, if the average particle size of the small particle components is 0.01 μm or larger, the viscosity of the resulting composition will not become too high, nor will the processability decrease. On the other hand, if it is less than 10 μm, there is no risk of the resulting composition becoming non-uniform, and a range of 0.01 μm to less than 10 μm is preferred, with a range of 0.1 to 4 μm being more preferred.

[0059] The ratio of large particles to small particles is not particularly limited, but a range of 9:1 to 1:9 (mass ratio) is preferred. Furthermore, the shape of the large and small particles is not particularly limited, and can be spherical, irregular, needle-shaped, etc. Irregular shape refers to any shape that has not undergone intentional spheroidizing treatment such as melting or granulation.

[0060] The average particle size can be determined, for example, as the volume-based average value (or median diameter) in particle size distribution measurement using laser diffraction.

[0061] The amount of component (D) is 10 to 97% by mass of the total composition, preferably 20 to 95% by mass, more preferably 30 to 95% by mass, and even more preferably 50 to 95% by mass. If the amount is greater than 97% by mass, the viscosity of the composition increases and the processability decreases. Also, if the amount is less than 10% by mass, the thermal conductivity becomes poor.

[0062] [(E) Platinum Group Metal Catalyst] Component (E) is a platinum group metal catalyst that functions to promote the addition reaction of the components described above. Conventional platinum group metal catalysts used in addition reactions can be used. Examples include platinum-based, palladium-based, and rhodium-based catalysts, but platinum or platinum compounds, which are relatively easy to obtain, are preferred. Examples include elemental platinum, platinum black, chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, and platinum coordination compounds. A single platinum group metal catalyst or a combination of two or more may be used.

[0063] The amount of component (E) is 0.01 to 1,000 ppm, preferably 10 to 1,000 ppm, based on the mass of platinum group metal atoms relative to the mass of component (A). If the amount of catalyst is less than the lower limit, the catalytic effect may not be obtained. Conversely, exceeding the upper limit does not increase the catalytic effect and is uneconomical, so it is undesirable.

[0064] [(F) Non-reactive phenyl-modified organopolysiloxane] In addition to the above components, a non-reactive phenyl-modified organopolysiloxane that does not undergo hydrosilylation reactions with components (A) and (B) or condensation reactions with component (C) may be used. That is, it is preferable that the heat-softening, heat-conductive silicone composition further contains a non-reactive phenyl-modified organopolysiloxane as component (F). The molecular structure of the non-reactive phenyl-modified organopolysiloxane is not particularly limited as long as it has the above properties, and examples include a linear structure, a branched structure, or a linear structure having a partially branched or cyclic structure. A linear structure is preferred.

[0065] Furthermore, component (F) has a phenyl group. The amount of phenyl groups in one molecule is preferably 10 to 100%, and more preferably 30 to 100%, of the number of siloxane units containing a phenyl group per side-chain siloxane unit. If the amount of phenyl groups in one molecule is 10% or more relative to the side-chain siloxane units, the change in viscosity at temperature of the thermo-softening, thermo-conductive silicone composition and the cured product is favorable.

[0066] Furthermore, from the viewpoint of viscosity, groups other than the phenyl group are preferably alkyl groups having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 8 carbon atoms. Examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, etc. It is also possible to use alkyl groups in which some of the hydrogen atoms are substituted with halogen atoms. Among alkyl groups, the methyl group is particularly preferred.

[0067] Furthermore, non-reactive phenyl-modified organopolysiloxanes have a kinematic viscosity of 100 to 100,000 mmHg at 25°C. ２ It is preferably / s, and more preferably 300 to 10,000 mm ２ / s, and more preferably 500 to 5,000 mm ２ It is / s. The kinematic viscosity is 100 mm ２ A value of 1 / s or higher is preferable because it indicates a sufficient phenyl modification rate. Also, a kinematic viscosity of 100,000 mm² is preferable. ２ A value of / s or less is preferable because it facilitates the handling of the thermosoftening, thermally conductive silicone composition.

[0068] The amount of component (F) is preferably 1 to 500 parts by mass, and more preferably 10 to 100 parts by mass, per 100 parts by mass of component (A). Such an amount is preferable because it allows for a reduction in viscosity of the composition and its cured product without reducing processability.

[0069] Component (F) may be used alone or in combination of two or more types.

[0070] [Other Components] Depending on the purpose and effects of the present invention, other components may be further added to the heat-softening, heat-conductive silicone composition of the present invention. For example, optional components such as hydrosilylation reaction regulators, heat-resistant improvers such as iron oxide, viscosity modifiers such as silica, and mold release agents may be added.

[0071] The viscosity of the thermosoftening, thermally conductive silicone composition of the present invention at 80°C is preferably 50% or less of the viscosity at 40°C, i.e., (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.5, and more preferably (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.3. If (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.5, the thermosoftening properties are sufficient. There is no particular lower limit, but for example, the viscosity of the thermosoftening, thermally conductive silicone composition of the present invention at 80°C can be 5% or more of the viscosity at 40°C, i.e., (viscosity at 80°C) / (viscosity at 40°C) ≥ 0.05.

[0072] The viscosity of the thermosoftening, thermally conductive silicone composition at 80°C and at 40°C was determined, for example, using a shear viscometer: HAAKE MARS40 Rheometer (manufactured by Thermo Fisher Scientific) (rotation speed 10s). －１ The values ​​measured by ) can be used.

[0073] [Manufacturing Process for Thermoflexible Thermal Conductive Silicone Composition] The manufacturing method for the thermoflexible thermal conductive silicone composition according to the present invention will now be described. The manufacturing method for the thermoflexible thermal conductive silicone composition according to the present invention is not particularly limited.

[0074] One method of mixing the above-mentioned components (A) to (E), and component (F) and other components as needed, is to use a mixer such as a rotation / revolution type mixer (product name: Awatori Rentaro, manufactured by THINKY Co., Ltd.), Trimix, Twinmix, Planetary Mixer (all manufactured by Inoue Seisakusho Co., Ltd.), Ultra Mixer (Mizuho Industries Co., Ltd.), or Hibiscus Disper Mix (Tokushu Kika Kogyo Co., Ltd.). Alternatively, all components may be mixed at once, or one or more components may be mixed in several stages.

[0075] In the present invention, it is preferable to first mix components (A), (C), and (D) at room temperature, and then mix in components (B) and (E), and component (F) and other components if present. Heating may be performed if necessary.

[0076] [Heat-softening thermally conductive silicone cured product] The present invention also provides a heat-softening thermally conductive silicone cured product which is obtained by curing the heat-softening thermally conductive silicone composition described above.

[0077] The heat-softening, thermally conductive silicone cured product of the present invention is heat-softening, similar to the heat-softening, thermally conductive silicone composition, and preferably has a viscosity at 80°C of 70% or less of the viscosity at 40°C, i.e., (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.7, more preferably (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.5, and even more preferably (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.3. If (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.7, the heat-softening properties are sufficient. There is no particular lower limit, but for example, the viscosity of the heat-softening, thermally conductive silicone cured product of the present invention at 80°C can be 5% or more of the viscosity at 40°C, i.e., (viscosity at 80°C) / (viscosity at 40°C) ≥ 0.05.

[0078] The viscosity of the heat-softening, heat-conducting silicone cured product at 80°C and at 40°C was measured using, for example, a shear viscometer: HAAKE MARS40 Rheometer (manufactured by Thermo Fisher Scientific) (rotation speed 10s). －１ The values ​​measured by ) can be used.

[0079] [Manufacturing Process for Heat-Softening Thermally Conductive Silicone Cured Products] The heat-softening thermally conductive silicone cured product of the present invention can be obtained by heating the heat-softening thermally conductive silicone composition of the present invention at a temperature of typically 40 to 180°C, preferably 60 to 150°C, and more preferably 80 to 120°C, which causes a hydrosilylation reaction between component (A) and component (B).

[0080] The present invention will be specifically described below using examples and comparative examples, but the present invention is not limited to these. The kinematic viscosity is the value measured using an Ostwald viscometer as described in JIS Z8803:2011.

[0081] Preparation of a heat-softening, heat-conductive silicone composition The components (A) to (F) used in the following examples and comparative examples are shown below. Me represents a methyl group, Ph represents a phenyl group, and Vi represents a vinyl group.

[0082] (A) Component (A-1): A component with a kinematic viscosity of 2,000 mm², represented by the following formula. ２ ・s －１ Phenyl-modified organopolysiloxane (phenyl modification rate: 66%)

[0083] (A-2): The kinematic viscosity is 700 mm, as expressed by the following formula. ２ ・s －１ Phenyl-modified organopolysiloxane (phenyl modification rate: 23%)

[0084] (A-3): The kinematic viscosity is 600 mm, as expressed by the following formula. ２ ・s ―１ organopolysiloxane

[0085] (A-4): Silicone resin D represented by the following formula ２５ T Φ ５５ D Ｖｉ ２０ However, D is Me ２ SiO ２／２ , T Φ PhSiO ３／２ , D Ｖｉ is ViMeSiO ２／２ That is the case.

[0086] (B) Component (B-1): Represented by the following formula, with a kinematic viscosity of 4 mm ２ ・s －１ Phenyl-modified organohydrogenpolysiloxane having hydrosilyl groups at both ends of the molecular chain.

[0087] (B-2): The kinematic viscosity is 20 mm, as expressed by the following formula.２ - s －１ Phenyl-modified organohydrogenpolysiloxane having hydrosilyl groups at both ends and side chains of the molecular chain

[0088] (B-3): Phenyl-modified organohydrogenpolysiloxane having a hydrosilyl group in the side chain, represented by the following formula and having a kinematic viscosity of 20 mm ２ - s －１ Phenyl-modified organohydrogenpolysiloxane having a hydrosilyl group in the side chain

[0089] Component (C) (C-1): Hydrolyzable organopolysiloxane represented by the following formula (aromatic hydrocarbon group content: 8.3%)

[0090] (C-2): Decyltrimethoxysilane represented by the following formula

[0091] Component (D) The average particle diameter of the thermal conductivity filler of component (D) was measured by a particle size distribution measuring device MT3000II (manufactured by Microtrac Bell Co., Ltd.). (D-1): Spherical aluminum powder (average particle diameter: 0.3 μm) (D-2): Spherical aluminum powder (average particle diameter: 12 μm) (D-3): Amorphous zinc oxide powder (average particle diameter: 1 μm)

[0092] Component (E) (E-1) 5% platinum chloride acid 2-ethylhexanol solution

[0093] Component (F) (F-1) Phenyl-modified organosiloxane represented by the following formula and having a kinematic viscosity of 380 mm ２ - s －１ Phenyl-modified organosiloxane

[0094] [Manufacturing Method] Thermoplastic Thermally Conductive Silicone Composition and Cured Product The components (A) to (F) were mixed as follows to obtain the compositions and cured products of the examples and comparative examples. The components (A), (C), (D), and (F) were weighed according to the composition ratios (parts by mass) shown in Table 1 and placed in a metal kettle of a planetary mixer (manufactured by Inoue Manufacturing Co., Ltd.). After stirring at room temperature and 30 rpm for 1 hour, the component (E) was added, and stirring was carried out at room temperature and 30 rpm for 30 minutes. Further, the component (B) was added, and stirring was carried out at room temperature and 30 rpm for 20 minutes to obtain a composition. Thereafter, after stirring at 100 °C and 30 rpm for 1 hour and then cooling to room temperature, a cured product was obtained.

[0095] [Evaluation Method] Thermoplasticity The obtained compositions and cured products were used to measure the viscosity at a rotation speed of 10 s using a viscosity and viscoelasticity measuring device (trade name: MARS40 (manufactured by Thermo Fisher Scientific K.K.)). －１ The measurement conditions were using a parallel plate at 40 °C and 80 °C, and the gap was 0.3 mm. The value indicating thermoplasticity is represented by (viscosity at 80 °C) / (viscosity at 40 °C). The results are shown in Table 1.

[0096] Thickness and Thermal Resistance of Thermoplastic Thermally Conductive Silicone Cured Product after Heat Pressure Bonding The thermoplastic thermally conductive silicone cured product was applied to an aluminum plate so that the thickness became 200 μm, and an aluminum plate was laminated from above, and the above thermoplastic thermally conductive silicone cured product was sandwiched between two aluminum plates. The thermoplastic thermally conductive silicone cured product sandwiched between two aluminum plates was heated at 80 °C for 60 minutes while applying a pressure of 137.9 kPa with a clip or the like. After cooling to room temperature, the thickness of the thermoplastic thermally conductive silicone cured product sandwiched between two aluminum plates was measured. For the thickness measurement, a micrometer (manufactured by Mitutoyo Corporation, model: M802-25VA) was used. Also, the thermal resistance of the thermoplastic thermally conductive silicone cured product was measured using a laser flash measuring machine (manufactured by NETZSCH, LFA467 HyperFlash). The results are shown in Table 1. The thickness of the thermoplastic thermally conductive silicone cured product in the present invention after heat pressure bonding is preferably 100 μm or less, and the thermal resistance is preferably 50 mm ２ ·K / W or less, more preferably 20 mm ２It is below kW.

[0097] [Reworkability] Wipeability The cured material obtained was applied to a thickness of 200 μm and attached to a module or aluminum plate, and left to stand for 24 hours. After that, the cured material was wiped off with a plastic spatula or paper towel without using a solvent, and evaluated as follows. The results are shown in Table 1. ○: Can be wiped off without a solvent ×: Cannot be wiped off without a solvent

[0098] In the table, the composition of each component is given in parts by mass.

[0099] As shown in Examples 1 to 5, compositions using a phenyl-modified organopolysiloxane without T units as component (A) and an organohydrogenpolysiloxane having two hydrosilyl groups at the terminal as component (B), and their cured products, exhibited thermal softening properties. Furthermore, they were found to be able to be wiped off without the use of solvents and to have excellent reworkability.

[0100] On the other hand, as in Comparative Example 1, when an organohydrogenpolysiloxane having hydrosilyl groups only in the side chains was used for component (B), the cured product was hard and its compressibility decreased. Furthermore, when the cured product was molded into a 200 μm sheet, the sheet was brittle and difficult to handle. As in Comparative Example 2, when an organopolysiloxane without phenyl groups was used for component (A), the composition and cured product showed almost no thermal softening properties. This is thought to be due to the small thermal expansion coefficient of dimethyl silicone. As in Comparative Example 3, when a thermoplastic silicone resin having T units was used for component (A), the composition showed thermal softening properties similar to Example 1, but it was found that wiping without solvent was difficult and reworkability decreased. This is thought to be due to the high tackiness derived from the silicone resin when using thermoplastic silicone resin.

[0101] From the above results, it was found that the heat-softening, heat-conductive silicone cured product according to the present invention exhibits heat softening properties comparable to those of a thermoplastic silicone resin having T units, and is superior to that of a thermoplastic silicone resin in terms of reworkability. Therefore, the heat-softening, heat-conductive silicone composition and cured product of the present invention, which do not contain a thermoplastic silicone resin, can become a novel heat-softening material.

[0102] This specification includes the following embodiments: [1] A thermosoftening, thermally conductive silicone composition characterized by comprising the following components (A) to (E): (A) Having two or more alkenyl groups in one molecule and having a kinematic viscosity of 100 to 100,000 mm at 25°C ２ / s and R' １ SiO ３／２ Phenyl-modified organopolysiloxane (in the formula R') that does not contain units (T units) １ (A) is a substituted or unsubstituted monovalent hydrocarbon group. (A): 100 parts by mass, (B) an organohydrogenpolysiloxane having at least two hydrosilyl groups at the molecular chain ends: in an amount such that the number of moles of hydrosilyl groups in component (B) is 0.1 to 3 moles per mole of alkenyl groups in component (A), (C) one or more selected from organopolysiloxanes having hydrolyzable functional groups and alkoxysilane compounds represented by the following general formula (2): 10 to 1,000 parts by mass, R ３ ｂ R ４ ｃ Si ( OR ５ ) ４－ｂ－ｃ (2) (wherein, R ３ R is an alkyl group having 6 to 15 carbon atoms, ４ R is an independent monovalent hydrocarbon group having 1 to 15 carbon atoms. ５(A) is an alkyl group having 1 to 6 carbon atoms independently, b is an integer from 1 to 3, c is an integer from 0 to 2, except that b + c is an integer from 1 to 3. (D) One or more thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, and metal nitrides: in an amount of 10 to 97% by mass of the whole composition, and (E) Platinum group metal catalyst: 0.01 to 1,000 ppm on a mass basis converted to platinum group metal atoms with respect to the mass of component (A). [2] The thermally softening thermally conductive silicone composition of [1] above, characterized in that the organopolysiloxane having a hydrolyzable functional group of component (C) is represented by the following general formula (1). (In the formula, R １ R is independently an aromatic hydrocarbon group having 6 to 10 carbon atoms, or independently an alkyl group having 1 to 10 carbon atoms. ２ (a) is an alkyl group having 1 to 4 carbon atoms. a is 2 or 3, and n is an integer between 2 and 60. (However, it contains 1% or more of an aromatic hydrocarbon group having 6 to 10 carbon atoms.) [3]: The thermosoftening thermoconductive silicone composition according to [1] or [2] above, characterized in that the thermosoftening thermoconductive silicone composition further contains a nonreactive phenyl-modified organopolysiloxane as component (F). [4]: ​​The thermosoftening thermoconductive silicone composition according to [3] above, characterized in that it contains component (F) in an amount of 1 to 500 parts by mass per 100 parts by mass of component (A). [5]: The thermosoftening thermoconductive silicone composition according to any one of [1] to [4] above, characterized in that the viscosity of the thermosoftening thermoconductive silicone composition at 80°C is 50% or less of the viscosity at 40°C, i.e., satisfies (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.5. [6]: A heat-softening, heat-conducting silicone cured product characterized in that it is a cured heat-softening, heat-conducting silicone composition obtained from any one of the above [1] to [5]. [7]: The heat-softening, heat-conducting silicone cured product according to [6], characterized in that the viscosity of the heat-softening, heat-conducting silicone cured product at 80°C is 70% or less of the viscosity at 40°C, i.e., (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.7.

[0103] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. A thermoplastic thermally conductive silicone composition, characterized by comprising the following components (A) to (E). (A) A phenyl-modified organopolysiloxane having two or more alkenyl groups in one molecule and a kinematic viscosity at 25°C of 100 to 100,000 mm ２ / s and not containing R’ １ SiO ３／２ units (T units) (where R’ １ is a substituted or unsubstituted monovalent hydrocarbon group): 100 parts by mass, (B) An organohydrogenpolysiloxane having at least two hydrosilyl groups at the molecular chain ends: an amount such that the molar number of hydrosilyl groups in component (B) is 0.1 to 3 moles with respect to 1 mole of the alkenyl groups in component (A), (C) One or more selected from organopolysiloxanes having hydrolyzable functional groups and alkoxysilane compounds represented by the following general formula (2): 10 to 1,000 parts by mass, R ３ ｂ R ４ ｃ Si(OR ５ ) ４－ｂ－ｃ (2) (In the formula, R ３ is independently an alkyl group having 6 to 15 carbon atoms, R ４ is independently a monovalent hydrocarbon group having 1 to 15 carbon atoms, R ５ is independently an alkyl group having 1 to 6 carbon atoms, b is an integer of 1 to 3, c is an integer of 0 to 2, provided that b + c is an integer of 1 to 3.) (D) One or more thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, and metal nitrides: an amount of 10 to 97% by mass based on the whole composition, and (E) A platinum group metal catalyst: 0.01 to 1,000 ppm on a mass basis in terms of platinum group metal atoms with respect to the mass of component (A).

2. The thermosoftening, thermally conductive silicone composition according to claim 1, characterized in that the organopolysiloxane having a hydrolyzable functional group of component (C) is represented by the following general formula (1). (In the formula, R １ R is independently an aromatic hydrocarbon group having 6 to 10 carbon atoms, or independently an alkyl group having 1 to 10 carbon atoms. ２ (where a is an alkyl group having 1 to 4 carbon atoms; a is 2 or 3, and n is an integer between 2 and 60; provided that it contains 1% or more of an aromatic hydrocarbon group having 6 to 10 carbon atoms.) 3. The thermosoftening, thermally conductive silicone composition according to claim 1, characterized in that the thermosoftening, thermally conductive silicone composition further contains a non-reactive phenyl-modified organopolysiloxane as component (F).

4. The thermosoftening, thermally conductive silicone composition according to claim 3, characterized in that it contains 1 to 500 parts by mass of component (F) per 100 parts by mass of component (A).

5. The thermosoftening, thermally conductive silicone composition according to claim 1, characterized in that the viscosity of the thermosoftening, thermally conductive silicone composition at 80°C is 50% or less of the viscosity at 40°C, i.e., (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.

5.

6. A heat-softening, heat-conducting silicone cured product, characterized in that it is a heat-softening, heat-conducting silicone composition according to any one of claims 1 to 5 that has been cured.

7. The heat-softening, heat-conducting silicone cured product according to claim 6, characterized in that the viscosity of the heat-softening, heat-conducting silicone cured product at 80°C is 70% or less of the viscosity at 40°C, i.e., (viscosity at 80°C) / (viscosity at 40°C) ≤ 0.7.

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