阅读说明：本技术 硅酮组合物及固化型油脂 (Silicone composition and curable grease ) 是由 水野贵瑛 小谷野茂 于 2020-03-25 设计创作，主要内容包括：提供在高比重软磁性填充材料未固化的状态下抑制沉淀且长期保存性优异的硅酮组合物及使该硅酮组合物固化而得到的固化型油脂。具有电磁波吸收性及导热性的硅酮组合物包括液状硅酮、比重4.5以上的高比重软磁性填充材料、比重4.0以下的中比重导热性填充材料以及非液状的增粘抑制防沉淀剂。另外,固化型油脂使在使用时混合使用的主剂和固化剂组合而成,是通过双组分固化型的混合而固化的双组分固化型的固化型油脂,所述主剂是本发明的硅酮组合物,液状硅酮是在末端具有乙烯基的有机聚硅氧烷,所述固化剂是本发明的硅酮组合物,液状硅酮是有机氢聚硅氧烷。(Provided are a silicone composition which suppresses precipitation in an uncured state of a high specific gravity soft magnetic filler and has excellent long-term storage stability, and a curable grease obtained by curing the silicone composition. The silicone composition having electromagnetic wave absorbability and thermal conductivity includes a liquid silicone, a high specific gravity soft magnetic filler having a specific gravity of 4.5 or more, a medium specific gravity thermal conductive filler having a specific gravity of 4.0 or less, and a non-liquid thickening-inhibiting anti-settling agent. The curable grease is a two-component curable grease which is obtained by combining a main agent and a curing agent, the main agent being the silicone composition of the present invention, the liquid silicone being an organopolysiloxane having a vinyl group at a terminal, the curing agent being the silicone composition of the present invention, and the liquid silicone being an organohydrogenpolysiloxane, and the curable grease being cured by mixing a two-component curable grease.)

1. A silicone composition, comprising:

liquid silicone;

a high specific gravity soft magnetic filler having a specific gravity of 4.5 or more;

a medium-specific gravity thermal conductive filler having a specific gravity of 4.0 or less; and

a non-liquid thickening-inhibiting anti-settling agent.

2. The silicone composition according to claim 1,

the thickening-inhibiting anti-settling agent is at least one selected from polysaccharides having a pyranose ring and nitrogen-containing polysaccharide polymers.

3. The silicone composition according to claim 1,

the viscosity-increasing and anti-settling agent is at least one selected from crystalline cellulose, powdered cellulose, starch, amylose, amylopectin, glycogen, dextrin, chitin and chitosan.

4. The silicone composition according to any one of claims 1 to 3, wherein,

the viscosity-increasing inhibition anti-settling agent is crystalline cellulose surface-coated with sodium carboxymethyl cellulose.

5. The silicone composition according to any one of claims 1 to 4, wherein,

the thickening/sedimentation inhibitor is an assembly of a plurality of crystalline cellulose particles, and has any shape of a substantially spherical shape, a particulate shape, a block shape, and an aggregated shape.

6. The silicone composition according to any one of claims 1 to 5, wherein,

the thickening-inhibiting anti-settling agent has an average particle size of 10 to 500 [ mu ] m.

7. The silicone composition according to any one of claims 1 to 6, wherein,

the repose angle of the viscosity-increasing inhibition anti-settling agent is 34-57 degrees.

8. The silicone composition according to any one of claims 1 to 7, wherein,

the high specific gravity soft magnetic filler material is at least one selected from the group consisting of ferrite, iron, and an iron-containing alloy.

9. A curable oil-and-fat composition comprising a combination of a main agent and a curing agent which are used as mixed components at the time of use, which is a two-component curable oil-and-fat composition curable by mixing of two-component curable oils,

the base silicone composition according to any one of claims 1 to 8, wherein the liquid silicone is an organopolysiloxane having a vinyl group at a terminal,

the curing agent is the silicone composition according to any one of claims 1 to 8, and the liquid silicone is an organohydrogenpolysiloxane.

Technical Field

The present invention relates to a silicone composition having electromagnetic wave absorbability and thermal conductivity, and a curable grease obtained by curing the silicone composition.

Background

In recent years, there has been an increasing demand for heat-generating electronic components to have higher density, smaller size, thinner thickness, and lighter weight. On the other hand, in order to dissipate heat generated from these electronic components, a heat dissipating body such as a heat sink is used. In order to improve the cooling effect, a heat conductive grease may be applied between the heat-generating electronic component and the radiator.

However, since the above-mentioned heat conductive grease includes silicone rubber, silicone oil, or the like, the heat conductivity is lower than that of a metal electronic component or a metal heat radiator. Therefore, a thermally conductive grease having a low viscosity and high fluidity is desired so as not to allow an air layer having extremely low thermal conductivity to enter between the electronic component and the heat sink. For the purpose of improving heat dissipation properties, for example, international publication No. 2016/103424 (patent document 1) discloses a silicone composition containing a liquid silicone, a filler that imparts an insolubilization function as a thermally conductive filler, and a non-liquid thickening-inhibiting anti-settling agent. Further, japanese patent No. 3957596 (patent document 2) discloses a thermally conductive grease composed of 5 to 20 mass% of silicone rubber; 15 to 35 mass% of organopolysiloxane containing 10 to 30 mass% of silicone oil as a component; 35 to 55 mass% of spherical alumina powder having an average particle diameter of 0.2 μm or more and less than 1.0 μm; and 30 to 50 mass% of aluminum nitride powder having an average particle diameter of 1 to 3 μm and a maximum particle diameter of 2 to 10 μm.

On the other hand, for example, a CPU used in a computer is highly required not only for high integration due to miniaturization but also for high-speed processing. High-speed processing significantly increases the operating frequency, and as a result, high-frequency components are generated. This high-frequency component becomes noise, and if noise appears on a signal of a communication line or the like, the electronic device may malfunction. Therefore, japanese patent application laid-open No. 2001-294752 (patent document 3) discloses an electromagnetic wave absorbing heat conductive silicone rubber composition comprising a soft magnetic metal powder and having a cured product with a thermal conductivity of 2.0W/m · K or more, from the viewpoint of heat dissipation and from the viewpoint of suppressing noise generated from electronic device elements such as CPUs.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2016/103424

Patent document 2: japanese patent No. 3957596

Patent document 3: japanese patent laid-open publication No. 2001 and 294752

Disclosure of Invention

Problems to be solved by the invention

Not only the CPU described above but also other electronic device elements are being highly integrated and processed at high speed. In particular, in an optical communication module which has been widely used in recent years, an ultrahigh frequency component of, for example, 10 to 20GHz, which is higher in frequency than a high frequency component (for example, 10MHz to 10GHz) generated by a CPU, is generated.

Accordingly, the present invention provides a silicone composition which suppresses the transmission of noise composed of a high-frequency component (for example, 10MHz to 10GHz) and also suppresses the transmission of noise composed of a ultrahigh-frequency component (for example, 10 to 20GHz), and which has a higher heat dissipation property than conventional silicone compositions and electromagnetic wave absorbability and thermal conductivity, and a curable grease obtained by curing the silicone composition.

Means for solving the problems

In order to achieve the above object, one aspect of the present invention is configured to have the following features.

Namely, a silicone composition according to an embodiment of the present invention includes: liquid silicone; a high specific gravity soft magnetic filler having a specific gravity of 4.5 or more; a medium-specific gravity thermal conductive filler having a specific gravity of 4.0 or less; and a non-liquid thickening-inhibiting anti-settling agent.

The silicone composition according to one embodiment of the present invention, which includes the high specific gravity soft magnetic filler having a specific gravity of 4.5 or more, can suppress not only the transmission of noise composed of high frequency components (for example, 10MHz to 10GHz) but also the transmission of noise composed of ultrahigh frequency components (for example, 10 to 20 GHz). In addition, the silicone composition according to an embodiment of the present invention includes a medium specific gravity thermal conductive filler having a specific gravity of 4.0 or less, and thus thermal conductivity is improved, and as a result, heat dissipation of the silicone composition is improved. In addition, the non-liquid thickening-inhibiting anti-settling agent included in the silicone composition according to one embodiment of the present invention can inhibit the precipitation of the high-specific-gravity soft magnetic filler and the medium-specific-gravity thermally conductive filler having a higher specific gravity than that of the liquid silicone in the silicone composition. Here, the viscosity and the compositional uniformity of the silicone composition are ensured by suppressing precipitation of the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler, and as a result, the heat dissipation can be maintained while suppressing an increase in viscosity and suppressing transmission of noise composed of a high frequency component and a ultrahigh frequency component.

In the silicone composition according to one embodiment of the present invention, the thickening-inhibiting anti-settling agent may be at least one selected from polysaccharides having a pyranose ring and nitrogen-containing polysaccharide polymers.

In the silicone composition according to one embodiment of the present invention, the viscosity-increasing suppressing anti-settling agent may be at least one selected from crystalline cellulose, powdered cellulose, starch, amylose, amylopectin, glycogen, dextrin, chitin and chitosan.

The polysaccharides, nitrogen-containing polysaccharide polymers, and the substances have a bulky structure and are insoluble in liquid silicone, which is relatively hydrophobic. Therefore, the above-mentioned polysaccharides, nitrogen-containing polysaccharide polymers and the above-mentioned substances have a function of floating in the liquid silicone. It is presumed that the polysaccharide, the nitrogen-containing polysaccharide polymer, and the substance having a low specific gravity relative to the liquid silicone are present below the high specific gravity soft magnetic filler and the medium specific gravity thermally conductive filler, respectively, thereby suppressing precipitation of the high specific gravity soft magnetic filler and the medium specific gravity thermally conductive filler. It is presumed that the viscosity and the compositional uniformity of the silicone composition are ensured by suppressing the precipitation of the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler in the silicone composition, and as a result, the increase in viscosity is suppressed.

In the silicone composition according to one embodiment of the present invention, the viscosity-increasing suppression anti-settling agent may be crystalline cellulose whose surface is coated with sodium carboxymethyl cellulose.

It is presumed that the thickening-inhibiting anti-settling agent, which is formed by coating the surface of crystalline cellulose with relatively hydrophilic sodium carboxymethyl cellulose, is insoluble in relatively hydrophobic liquid silicone. Further, since crystalline cellulose itself is bulky, it has a lower specific gravity than liquid silicone. Therefore, the crystalline cellulose surface-coated with sodium carboxymethyl cellulose has a property of floating in liquid silicone. From this, it is presumed that the precipitation of the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler having a higher specific gravity than that of the liquid silicone is suppressed by the buoyancy of the crystalline cellulose whose surface is coated with the sodium carboxymethyl cellulose. Further, it is presumed that the viscosity and the compositional uniformity of the silicone composition are ensured by suppressing the precipitation of the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler, and as a result, the increase in viscosity is suppressed.

In the silicone composition according to one embodiment of the present invention, the thickening-inhibiting anti-settling agent may be an assembly of a plurality of crystalline cellulose particles, and may be an assembly having any shape of a substantially spherical shape, a granular shape, a massive shape, and an aggregated shape.

By forming a plurality of crystalline cellulose particles into an aggregate having such a shape as described above, a thickening-inhibiting anti-settling agent having a larger volume can be obtained. Therefore, the aggregate of a plurality of crystalline cellulose particles having a larger volume has a lower specific gravity than the primary particles of crystalline cellulose. From this, it is presumed that the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler having higher specific gravity than the liquid silicone inhibit precipitation by buoyancy of the aggregate of the plurality of crystalline cellulose particles existing below them. Further, it is presumed that the viscosity and the compositional uniformity of the silicone composition are ensured by suppressing the precipitation of the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler, and as a result, the increase in viscosity is suppressed.

In the silicone composition according to one embodiment of the present invention, the thickening inhibitor/anti-settling agent may have an average particle diameter of 10 to 500 μm.

By setting the average particle diameter of the thickening-control anti-settling agent in the above range, it is possible to suppress the sedimentation of the high-specific-gravity soft magnetic filler and the medium-specific-gravity thermal conductive filler having a higher specific gravity than that of the liquid silicone. The average particle size will be described later.

In the silicone composition according to one embodiment of the present invention, the viscosity increasing inhibitor/anti-settling agent may have an angle of repose of 34 ° to 57 °.

Here, the angle of repose is determined by the size of the particle, the rounded corner of the particle, and the shape. By setting the angle of repose of the thickening-control anti-settling agent to the above range, it is possible to suppress the settling of the high-specific-gravity soft magnetic filler and the medium-specific-gravity thermal conductive filler having a higher specific gravity than the liquid silicone.

In the silicone composition according to one embodiment of the present invention, the high specific gravity soft magnetic filler may be at least one selected from the group consisting of ferrite, iron, and an iron-containing alloy.

By using at least one selected from the group consisting of ferrite, iron, and an iron-containing alloy as the high specific gravity soft magnetic filler, it is possible to suppress not only noise due to a high frequency component (for example, 10MHz to 10GHz) but also noise due to an ultrahigh frequency component (for example, 10 to 20GHz) for a long period of time.

The curable grease according to one aspect of the present invention is a two-component curable grease which is obtained by combining a main agent and a curing agent which are used by mixing at the time of use and is cured by mixing a two-component curable grease, and can be formed such that the main agent is the silicone composition according to any one of the above aspects, the liquid silicone is an organopolysiloxane having a vinyl group at a terminal, the curing agent is the silicone composition according to any one of the above aspects, and the liquid silicone is an organohydrogenpolysiloxane.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the silicone composition of one embodiment of the present invention, transmission of noise composed of not only a high-frequency component (for example, 10MHz to 10GHz) but also an ultrahigh-frequency component (for example, 10 to 20GHz) is suppressed, and heat dissipation is further excellent, as compared with conventional silicone compositions. The curable grease of the present invention suppresses transmission of noise including high-frequency components and ultrahigh-frequency components, and has more excellent heat dissipation properties than conventional heat-conductive greases.

Detailed Description

[ Silicone composition ]

The present invention will be described in detail based on embodiments. The silicone composition according to an embodiment of the present invention is characterized by including: liquid silicone; a high specific gravity soft magnetic filler having a specific gravity of 4.5 or more; a medium-specific gravity thermal conductive filler having a specific gravity of 4.0 or less; and a non-liquid thickening-inhibiting anti-settling agent. In the present specification, hereinafter, the "high specific gravity soft magnetic filler having a specific gravity of 4.5 or more" may be simply referred to as a "high specific gravity soft magnetic filler". Similarly, "a medium-specific gravity thermal conductive filler having a specific gravity of 4.0 or less" may be abbreviated as "a medium-specific gravity thermal conductive filler". In addition, the "non-liquid thickening/sedimentation inhibiting agent" may be abbreviated as "thickening/sedimentation inhibiting agent".

By including the high specific gravity soft magnetic filler having a specific gravity of 4.5 or more in the silicone composition according to one embodiment of the present invention, it is possible to suppress noise due to not only high-frequency components (for example, 10MHz to 10GHz) but also ultrahigh-frequency components (for example, 10 to 20GHz) for a long period of time. In addition, the silicone composition according to an embodiment of the present invention includes liquid silicone, and is particularly excellent in heat resistance. Further, the silicone composition according to an embodiment of the present invention includes a medium specific gravity thermal conductive filler having a specific gravity of 4.0 or less, and thus thermal conductivity is improved, and as a result, heat dissipation of the silicone composition is improved. In addition, the non-liquid thickening-inhibiting anti-settling agent included in the silicone composition according to one embodiment of the present invention can inhibit the sedimentation of the high-specific-gravity soft magnetic filler and the medium-specific-gravity thermal conductive filler having a higher specific gravity than that of the liquid silicone in the silicone composition. Further, by suppressing the precipitation of the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler, the viscosity and the compositional uniformity of the silicone composition are ensured, and as a result, the increase in viscosity is suppressed, and the heat dissipation can be maintained while suppressing the noise composed of the high frequency component and the ultrahigh frequency component for a long period of time. That is, the silicone composition according to one embodiment of the present invention is superior to conventional silicone compositions in heat dissipation and electromagnetic wave absorption, and can maintain these properties for a long period of time.

Next, the structure of the silicone composition according to one embodiment of the present invention will be described in detail.

< liquid silicone >)

First, liquid silicone is explained. The liquid silicone used in one embodiment of the present invention includes both a liquid silicone that does not have curability and a curable liquid silicone. Specific examples of the liquid silicone include: organopolysiloxanes such as dimethylpolysiloxanes and methylphenylpolysiloxanes; modified silicones substituted with reactive groups such as hydrocarbon groups, epoxy groups, acryl groups, and amino groups. The liquid silicone is not particularly limited as long as it can be used for the application of one embodiment of the present invention, but for example, an addition reaction type liquid silicone is preferable because high flexibility is desired for the application of electromagnetic wave absorption and heat dissipation. Since addition reaction type liquid silicone has a small cure shrinkage, a gap is less likely to be formed when a heat generating body such as an electronic device element and a heat radiating body such as a heat sink are embedded by curing.

Examples of the addition reaction type liquid silicone include a one-component reaction type organopolysiloxane having both a vinyl group and an H — Si group in one molecule, a two-component silicone including an organopolysiloxane having a vinyl group at a terminal or in a side chain, and an organohydrogenpolysiloxane having two or more H — Si groups at a terminal or in a side chain. For example, the trade names "KE-1057", "KE-1012-A/B", manufactured by shin-Etsu chemical Co., Ltd, "EG-4000", manufactured by Tooli Dow Corning Co., Ltd, "SL 5100", manufactured by KCC, and "SL 5152" are preferable.

When an organopolysiloxane having a vinyl group is used as the addition reaction type silicone, a silane coupling agent is used as a curing agent, and the curing agent is heated to obtain a cured product. When an organopolysiloxane having a vinyl group and an organohydrogenpolysiloxane having an H — Si group are used as the addition reaction type silicone, a platinum catalyst is used as a catalyst, and the reaction mixture is heated and cured to obtain a cured product.

Examples of the silane coupling agent include a vinyl silane coupling agent, an ammonia silane coupling agent, and an epoxy silane coupling agent, but a vinyl silane coupling agent is preferable as a reactive curing agent for liquid silicone. For example, the trade name "KBE-1003" manufactured by shin-Etsu chemical industries, Ltd is preferable.

Examples of the platinum catalyst include platinum and platinum compounds. For example, "SXR-212 CATALYST" available from shin-Etsu chemical Co., Ltd is preferable.

The amount of the silane coupling agent added is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, based on the liquid silicone, from the viewpoint of obtaining a cured product having high flexibility.

The viscosity of the liquid silicone is preferably 0.005 pas to 2 pas. When the viscosity of the liquid silicone is less than 0.005Pa · s, the liquid silicone has a low molecular weight, and therefore the molecular weight is unlikely to increase even after curing. Therefore, a cured product obtained by curing the silicone composition may become brittle. On the other hand, if the viscosity of the liquid silicone exceeds 2Pa · s, the viscosity of the silicone composition tends to increase. Thus, the amounts of the high specific gravity soft magnetic filler, the medium specific gravity thermal conductive filler, and the viscosity-increasing control anti-settling agent may be less than predetermined amounts in order to fall within a desired viscosity range of the silicone composition as a final product. As a result, a cured product (for example, a curable grease) obtained by curing the silicone composition may not have desired electromagnetic wave absorbability and thermal conductivity.

Soft magnetic filler material with high specific gravity of 4.5 or more

Next, a high specific gravity soft magnetic filler having a specific gravity of 4.5 or more will be described. The high specific gravity soft magnetic filler having a specific gravity of 4.5 or more is mainly blended in order to suppress noise composed of not only high frequency components (for example, 10MHz to 10GHz) but also ultrahigh frequency components (for example, 10 to 20 GHz). In the present specification, the specific gravity is 1.0g/cm, which is the density of the object divided by the density of water³The values obtained are reported.

The high specific gravity soft magnetic filler is not particularly limited as long as it is a filler having soft magnetism. Here, the soft magnetic property means that internal magnetization is easily matched with a magnetic field direction, that is, magnetization is easily performed with respect to a magnetic field applied from the outside. The term "hard magnetic property" refers to a property that internal magnetization is hardly generated even when an external magnetic field is applied, and a magnetic field is applied to the outside.

Examples of the high specific gravity soft magnetic filler include ferrite, iron, and an iron-containing alloy. These soft magnetic metal powders may be used alone or in combination of two or more. Examples of the iron-containing alloy include Fe-Ni (permalloy), Fe-Co, Fe-Cr, Fe-Si, Fe-Al, Fe-Cr-Si, Fe-Cr-Al, and Fe-Al-Si alloys.

The ferrite has a specific gravity of 4.5 to 6.0. The ferrite is iron oxide (Fe)₂O₃) Compound (MO. Fe) with divalent Metal Oxide (MO)₂O₃). In addition, the following are classified according to the type of the divalent metal oxide: spinel type ferrites such as Mn-Zn type, Mg-Zn type, Ni-Zn type, Cu-Zn-Mg type, Cu-Ni-Zn type, Li-Fe type, etc.; with R₃Fe₅O₁₂A garnet ferrite of YFe system or the like represented by (R is Y having a valence of 3 or a rare earth element); and Me is Fe, Ni, Co or Cu, has the formula MeO, BaO or Fe₂O₃A hexagonal lattice type ferrite of a hexagonal structure such as BaFe system.

Among them, ferrite containing Ni, Mn, Zn, Y and Ba is preferable. In particular, spinel type ferrite such as Mn-Zn system and Ni-Zn system and hexagonal lattice type ferrite such as BaFe system are preferable, and the use of these ferrites can improve the permeability.

The Ni-Zn ferrite has a general formula of (NiO) x (ZnO) y. Fe₂O₃The composition shown. However, the Ni — Zn ferrite may be a ferrite in which a part of Ni is replaced with another divalent metal such as Cu, Mg, Co, or Mn. The Ni — Zn ferrite may contain other elements within a range that does not deteriorate the original characteristics.

The Mg-Zn ferrite has a general formula of (MgO) x (ZnO) y. Fe₂O₃Composition of the representation. However, ferrite in which a part of Mg is replaced with another divalent metal such as Ni, Cu, Co, Mn, or the like may be used. The Mg — Zn ferrite may contain other elements within a range that does not deteriorate the original characteristics.

The Mn-Zn ferrite has a general formula of (MnO) x (ZnO) y. Fe₂O₃Composition of the representation. However, ferrite in which a part of Mn is substituted with another divalent metal such as Ni, Cu, Co, and Mg may be used. The Mn — Zn ferrite may contain other elements within a range that does not deteriorate the original characteristics.

The Cu-based ferrite has a general formula of (CuO) x-Fe₂O₃Composition of the representation. However, ferrite in which a part of Cu is replaced with another divalent metal such as Ni, Zn, Mg, Co, Mn, or the like may be used. The Cu-based ferrite may contain other elements within a range that does not deteriorate the original characteristics.

The ferrite used in one embodiment of the present invention can be obtained by a known method. Fe as a raw material for ferrite which is a magnetic material of these oxides₂O₃、MnO₂、MnCO₃、CuO、NiO、MgO、ZnO、Y₂O, BaO, and metal oxides, metal carbonates, and the like are typical raw materials. As a method for producing a soft magnetic ferrite, a dry method, a coprecipitation method, and a spray pyrolysis method are typical production methods.

The particle shape of the high specific gravity soft magnetic filler is not particularly limited, and examples thereof include spherical, granular, and irregular shapes, and shapes having shape anisotropy such as a needle shape, a rod shape, a flat cylindrical shape, and a hollow shape. The particle shape of the preferred high specific gravity soft magnetic filler is preferably a shape having a small shape anisotropy in order to avoid an increase in viscosity of the silicone composition contained therein, and the aspect ratio of such a high specific gravity soft magnetic filler having a small shape anisotropy is preferably 1.0 to 10.0, and more preferably 1.0 to 5.0.

The high specific gravity soft magnetic filler may be used alone or in combination of two or more kinds. The average particle diameter of the high specific gravity soft magnetic filler is a value of 50% diameter (volume average diameter MV) in the volume-based cumulative fraction measured by the laser diffraction scattering particle size distribution measuring apparatus. When the high specific gravity soft magnetic filler is flat, it is preferably 0.1 to 500 μm, and more preferably 10 to 300 μm. On the other hand, when the high specific gravity soft magnetic filler is substantially spherical, it is preferably 0.1 to 300 μm, and more preferably 10 to 200 μm. When the average particle size is smaller than this range, the effect of suppressing noise composed of a high-frequency component and a ultrahigh-frequency component is small, and when the average particle size is larger than this range, precipitation suppression is difficult to be exhibited by a non-liquid thickening-suppressing anti-settling agent described later. Further, by subjecting the surface of the high specific gravity soft magnetic filler to surface treatment such as insulating coating or silane coupling agent treatment, the dispersibility into liquid silicone can be improved, or the electromagnetic wave absorbability of the obtained silicone composition can be improved.

The average particle diameter disclosed in the present specification is measured by a laser diffraction scattering method (JISR 1629: 1997) using a laser diffraction scattering particle size distribution measuring apparatus. The average particle diameter of the powder of the "high specific gravity soft magnetic filler", the "medium specific gravity thermal conductive filler" and the "non-liquid thickening inhibitor anti-settling agent" used in the present invention was measured by the above-described measurement method.

The amount of the high specific gravity soft magnetic filler blended is preferably 200 to 1500 parts by mass, more preferably 300 to 1200 parts by mass, and still more preferably 350 to 1100 parts by mass, based on 100 parts by mass of the liquid silicone. If the amount of the high specific gravity soft magnetic filler blended is less than the above range, sufficient magnetic properties may not be obtained, and if it exceeds the above range, moldability of the silicone composition after curing may be deteriorated.

Middle specific gravity heat conductive filling material with specific gravity below 4.0

Next, a medium specific gravity thermal conductive filler having a specific gravity of 4.0 or less will be described. The specific gravity thermal conductive filler is blended mainly for the purpose of improving the heat dissipation property of the silicone composition according to one embodiment of the present invention.

Examples of the medium-specific gravity heat conductive filler having a specific gravity of 4.0 or less include aluminum, aluminum oxide, magnesium oxide, quartz, boron nitride, aluminum nitride, silicon carbide, aluminum hydroxide, graphite, and carbon fiber. The medium-specific gravity thermal conductive filler preferably has a specific gravity of 3.0 or less. Examples of the medium-specific gravity thermal conductive filler having a specific gravity of 3.0 or less include aluminum, aluminum hydroxide, quartz, graphite, and carbon fiber. The lower the specific gravity of the medium-specific gravity thermal conductive filling material is, the more difficult the medium-specific gravity thermal conductive filling material is to precipitate in the silicone composition. In the present invention, one kind of the medium specific gravity thermal conductive filler may be used alone, or two or more kinds may be used in combination.

The average particle diameter of the medium specific gravity heat conductive filler is preferably 0.3 to 200 μm. The "average particle diameter" of the medium-specific gravity thermal conductive filler was determined by using the above-mentioned JISR 1629: 1997 "average particle size" measurement method. Here, when the average particle diameter of the specific gravity thermal conductive filler is less than 0.3 μm, the viscosity of the silicone composition is significantly increased. Therefore, since the medium specific gravity thermal conductive filler material cannot be highly filled, a silicone composition having desired thermal conductivity cannot be obtained. On the other hand, when the average particle diameter of the medium-specific-gravity thermal conductive filler exceeds 200 μm, the precipitation rate may not be sufficiently reduced even if the effect of inhibiting precipitation by a non-liquid viscosity-increasing-inhibition anti-precipitation agent described later is exerted. Two or more kinds of medium specific gravity thermal conductive filler having different average particle diameters may be used in combination. The filling ratio into the silicone composition can be improved.

The shape of the medium specific gravity thermal conductive filler is preferably spherical or approximately polyhedral spherical. By forming the filler into a spherical shape or a spherical shape that is nearly polyhedral, the specific surface area of the medium specific gravity thermal conductive filler can be reduced compared to other shapes. By reducing the specific surface area of the medium-specific gravity thermal conductive filler material, even if a large-particle-diameter medium-specific gravity thermal conductive filler material is present in the entire medium-specific gravity thermal conductive filler material and the proportion thereof is increased, the fluidity of the silicone composition is difficult to be reduced. In addition, the silicone composition can be maintained at a desired viscosity and the thermal conductivity can be improved by increasing the amount of the medium-specific gravity thermal conductive filler to be blended, as the case may be.

The amount of the medium-specific-gravity thermal conductive filler is preferably in the range of 200 to 1500 parts by mass per 100 parts by mass of the liquid silicone. When the amount of the medium-specific-gravity thermally conductive filler is less than 200 parts by mass, the silicone composition cannot exhibit sufficient thermal conductivity. On the other hand, if the amount of the medium-specific-gravity thermally-conductive filler is more than 1500 parts by mass, the viscosity of the silicone composition becomes too high, and there is a fear that the coating operation of the silicone composition becomes difficult.

< non-liquid thickening-inhibiting anti-settling agent >

Next, a non-liquid thickening-inhibiting anti-settling agent will be described. The thickening-inhibiting anti-settling agent used here functions to inhibit an increase in the viscosity of the system by adding the thickening-inhibiting anti-settling agent, and to prevent the high-specific-gravity soft magnetic filler and the medium-specific-gravity thermally conductive filler from settling, particularly from settling. Unlike a general low-viscosity liquid which lowers the viscosity, a non-liquid thickening inhibitor or a non-liquid anti-setting agent exists in a non-liquid form such as a solid form or a gel form in a silicone composition prepared by blending.

Examples of the thickening-inhibiting anti-settling agent include polysaccharides having a pyranose ring and nitrogen-containing polysaccharide polymers. Specific examples of the thickening-inhibiting anti-settling agent include crystalline cellulose, powdered cellulose, starch, amylose, amylopectin, glycogen, dextrin, chitin, chitosan, and the like. Amylose has a structure in which a plurality of α -glucosyl bonds (condensation polymerization) are present, and is linear. Amylopectin has a structure in which a plurality of α -glucose linkages (condensation) are bonded, and has a branch. Glycogen has more branches. Starch has a helical conformation in which amylose is coated with amylopectin. Dextrins have a plurality of α -glucose linkages (condensation) configuration. Chitin and chitosan are linear chains having a polyglucosamine structure.

In one embodiment of the present invention, one kind of the thickening-inhibiting anti-settling agent may be used alone, or two or more kinds may be used in combination. As the polysaccharide, a cellulose-based compound is also preferable in terms of excellent moisture resistance. The thickening-inhibiting anti-settling agent used in one embodiment of the present invention is preferably crystalline cellulose whose surface is coated with sodium carboxymethyl cellulose.

In particular, crystalline cellulose is not in a liquid state, but is less likely to cause an increase in viscosity with respect to liquid silicone. Crystalline cellulose can be extracted from cellulose microcrystals obtained by depolymerizing alpha-cellulose obtained from fibrous plants as pulp with an acid. Has a plurality of crystalline regions of cellulose, molecular chains of which are densely and regularly present. As the crystalline cellulose, in addition to the cellulose directly dried to be in powder form, as described above, the cellulose dried to be in powder form after the surface is coated with a water-soluble polymer (polysaccharide, saccharide, etc.) is used. In particular, in the case of crystalline cellulose whose surface is coated with sodium carboxymethylcellulose (CMC-Na), the precipitation inhibiting effect of the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler in the liquid silicone is high because the crystalline cellulose becomes a secondary aggregate of the crystalline cellulose and has a large volume.

The crystallinity of the crystalline cellulose is preferably 70 to 90, more preferably 80 to 90. The crystallinity of cellulose is mainly affected by the raw material slurry and the production method, and powdery cellulose produced by mechanical treatment alone without acid treatment has low crystallinity. If the crystallinity is low, the time required for heating and vulcanizing becomes long, and workability deteriorates, and mechanical properties also deteriorate. When the crystallinity is 80 or more, it is confirmed that the influence on the vulcanization rate is not large.

Although the mechanism of preventing precipitation by the thickening-inhibiting anti-settling agent is not clear, the polysaccharides, nitrogen-containing polysaccharide polymers, and the substances described above all have bulky structures and do not dissolve in liquid silicone, which is relatively hydrophobic. Therefore, the above-mentioned polysaccharides, nitrogen-containing polysaccharide polymers and the above-mentioned substances have a function of floating in the liquid silicone. Thus, it is presumed that the high-specific-gravity soft magnetic filler and the medium-specific-gravity thermally conductive filler are inhibited from precipitating by the buoyancy of each of the thickening-inhibiting anti-precipitation agents, because each of the thickening-inhibiting anti-precipitation agents is present below the high-specific-gravity soft magnetic filler and the medium-specific-gravity thermally conductive filler. Further, it is presumed that the silicone composition suppresses the viscosity of the silicone composition by suppressing the precipitation of the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler, thereby ensuring the uniformity of the viscosity and composition of the silicone composition.

In addition, the thickening-inhibiting anti-settling agent may be an assembly of a plurality of crystalline cellulose particles, and may be an assembly having any shape of a substantially spherical shape, a granular shape, a massive shape, or an aggregated shape, from the viewpoint of inhibiting the precipitation of the high-specific-gravity soft magnetic filler and the medium-specific-gravity thermal conductive filler. The thickening-inhibiting anti-settling agent is an aggregate of any of the above shapes, and thus has a larger volume and a low specific gravity. Therefore, it is presumed that, in the aggregate of the plurality of crystalline cellulose particles having a low specific gravity with respect to the liquid silicone, the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler located above the aggregate of the plurality of crystalline cellulose particles are inhibited from precipitating in the liquid silicone by the buoyancy of the aggregate of the plurality of crystalline cellulose particles.

The thickening-inhibiting anti-settling agent preferably has an average particle diameter of 0.1 to 500 μm, more preferably 10 to 500 μm, and still more preferably 20 to 500 μm. The "average particle diameter" of the thickening-inhibiting anti-settling agent was determined by the method according to JISR1629 described above: 1997 "average particle size" measurement method. When the average particle diameter of the thickening-inhibiting anti-settling agent is less than 0.1 μm, the precipitation inhibition of the high specific gravity soft magnetic filler becomes insufficient in particular. On the other hand, if the average particle diameter of the thickening-inhibitor anti-settling agent exceeds 500 μm, the viscosity of the silicone composition may increase.

The angle of repose of the thickening-inhibiting anti-settling agent is preferably 34 ° to 57 °, more preferably 34 ° to 52 °, and still more preferably 34 ° to 48 °. The method for measuring the angle of repose is according to JISR 9301-2-2: 1999(ISO 902: 1976). When the angle of repose of the thickening-inhibiting anti-settling agent is less than 34 °, the powder falling rate is high, the powder flowability is good, and the workability is improved. On the other hand, if the repose angle of the thickening-control anti-settling agent exceeds 57 °, the powder flowability deteriorates, which is not preferable in terms of work.

The amount of the thickening-inhibiting anti-settling agent to be blended is preferably 1.0 to 50 parts by mass, more preferably 3.0 to 30 parts by mass, and still more preferably 5.0 to 20 parts by mass, per 100 parts by mass of the liquid silicone. If the blending amount of the thickening-inhibiting anti-settling agent is less than 2.0 parts by mass, the anti-settling effect cannot be obtained. On the other hand, if the blending amount of the thickening-inhibiting anti-settling agent exceeds 50 parts by mass, the amount of the thickening-inhibiting anti-settling agent in the silicone composition becomes excessive, and the thermal conductivity may be low. As the thickening-inhibiting anti-settling agent of the present embodiment, other powdery anti-settling agents such as fine powder silica, organically treated clay, organically treated bentonite, and the like can be used in addition to the polysaccharide having a pyranose ring and the nitrogen-containing polysaccharide polymer.

< other additional materials >

The silicone composition having the above composition can contain various additives within a range not to impair the function thereof. For example, a dispersant, a flame retardant, a coupling agent, a plasticizer, a curing retarder, an antioxidant, a colorant, a catalyst, and the like may be added as appropriate.

The above components are mixed and stirred well to obtain a silicone composition.

The viscosity of the silicone composition obtained by stirring is 30 to 700 pas at 23 ℃. When the viscosity of the silicone composition is less than 30Pa · s, the amount of the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler to be blended is small, and as a result, sufficient thermal conductivity and electromagnetic wave absorbability may not be obtained. On the other hand, if the viscosity of the silicone composition exceeds 700Pa · s, the coating operation of the silicone composition becomes difficult. The above viscosity was measured at a rotational speed of 5rpm and 10rpm and a measurement temperature of 23 ℃ by using a spindle of spindle No. SC4-14 in a viscometer (product name "BROOKFIELD rotational viscometer DV-E") as described later.

[ curing type oil ]

The curable grease according to an embodiment of the present invention is a two-component curable grease in which a base compound and a curing agent to be mixed at the time of use are combined and which is cured by mixing a two-component curable grease. The main agent is the silicone composition described above, and the liquid silicone is an organopolysiloxane having a vinyl group at an end. The curing agent is the silicone composition, and the liquid silicone is an organohydrogenpolysiloxane having two or more H-Si groups at a terminal or a side chain.

The main agent and the curing agent used for the curable oil and fat have already been described, and therefore, the description thereof is omitted here.

[ examples ] A method for producing a compound

Next, an embodiment of the present invention will be described in further detail based on examples (comparative examples).

< preparation of sample >

Sample No. 1-1：

As the liquid silicone 1, 100 parts by mass of a vinyl-terminated organopolysiloxane (specific gravity 1, trade name: KE-1012-A, manufactured by shin-Etsu chemical Co., Ltd.) as an addition reaction type liquid silicone, 760 parts by mass of a soft magnetic Ni-Zn ferrite (average particle diameter: 80 μm, specific gravity: 5.18) as a high specific gravity soft magnetic filler, 200 parts by mass of a spherical alumina 1 (average particle diameter: 4.5 μm, specific gravity: 3.94) as a medium specific gravity thermal conductive filler, 100 parts by mass of a spherical alumina 2 (average particle diameter: 3 μm, specific gravity: 3.94) and 80 parts by mass of a spherical alpha-alumina single crystal particles (average particle diameter: 0.5 μm, specific gravity: 3.94) in the form of a polyhedron and 40 parts by mass of an aluminum hydroxide (average particle diameter: 1 μm, specific gravity: 2.4) were blended, 1 part by mass of a vinyl silane coupling agent (specific gravity: 1), 0.3 part by mass of a platinum catalyst (specific gravity: 1) and 6 parts by mass of crystalline cellulose (average particle diameter: 21 μm) having a surface coated with sodium carboxymethylcellulose as the thickening-inhibiting anti-settling agent 1 were mixed by stirring with a planetary mixer to prepare a silicone composition 1A (main agent).

Samples 1 to 2：

Silicone composition 1B (curing agent) was prepared by mixing the components in the same manner as in sample 1-1 except that 100 parts by mass of an organohydrogenpolysiloxane (specific gravity 1, trade name: KE-1012-B, manufactured by shin-Etsu chemical Co., Ltd.) having two or more H-Si groups at the end, which is an addition reaction type liquid silicone, was prepared as liquid silicone 2 in place of liquid silicone 1 used in sample 1, and that no platinum catalyst was prepared.

As described later, the silicone composition 1A (main agent) of sample 1-1 and the silicone composition 1B (curing agent) of sample 1-2 were mixed and left to stand for about 24 hours to cure, and were a two-component curing type curable grease. The main agent and the curing agent are sometimes expressed as an a agent and a B agent.

Sample No. 2-1：

In sample 2-1, a silicone composition 2A was prepared in the same manner as in sample 1-1, except that the amount of "crystalline cellulose having a surface coated with sodium carboxymethylcellulose" used as the thickening-inhibiting anti-settling agent 1 in sample 1-1 was changed from 6 parts by mass to 12 parts by mass.

Sample No. 2-2：

In sample 2-2, a silicone composition 2B was prepared in the same manner as in sample 1-2, except that the amount of "crystalline cellulose having a surface coated with sodium carboxymethylcellulose" used as the thickening-inhibiting anti-settling agent 1 in sample 1-2 was changed from 6 parts by mass to 12 parts by mass.

The silicone composition 2A of sample 2-1 and the silicone composition 2B of sample 2-2 are two-component curing type curable oils and fats which are mixed and left to stand for about 24 hours to be cured, as described later.

Samples 3-1 and 4-1：

In samples 3-1 and 4-1, a vapor phase mixed oxide (SiO) was used as the thickening-inhibiting anti-settling agent 2 in place of the thickening-inhibiting anti-settling agent 1 used in sample 1-1₂With Al₂O₃Mixture of (a), trade name: AEROSIL (registered trademark) COK84, japan AEROSIL co., ltd.) was prepared at the amounts (1.7 parts by weight and 3.4 parts by weight) described in table 2, respectively, and mixed in the same manner as in sample 1-1 to prepare silicone compositions 3A and 4A.

Samples 3-2 and 4-2：

In samples 3-2 and 4-2, a vapor phase mixed oxide (SiO) was used as the thickening-inhibiting anti-settling agent 2 in place of the thickening-inhibiting anti-settling agent 1 in sample 1-2₂With Al₂O₃Mixture of (a), trade name: AEROSIL (registered trademark) COK84, manufactured by Nippon AEROSIL Co., Ltd.), and mixing them in the same manner as in sample 1-2 except that they were blended in amounts (1.7 parts by weight and 3.4 parts by weight) described in Table 2, respectively, to prepare siliconKetone compositions 3B and 4B.

The silicone compositions 3A and 4A of the samples 3-1 and 4-1 and the silicone compositions 3B and 4B of the samples 3-2 and 4-2 were two-component curing type curable oils and fats which were mixed and left to cure for about 24 hours, respectively, as described later.

Control samples 1-1 and 1-2：

With respect to control sample 1-1, silicone composition 1A' was prepared in the same manner as in sample 1-1, except that the thickening inhibitor/anti-settling agent 1 used in sample 1-1 was not added. Further, with respect to control sample 1-2, silicone composition 1B' was prepared in the same manner as in sample 1-2 except that the thickening-inhibiting anti-settling agent 1 used in sample 1-2 was not added.

The silicone composition 1A 'of the control sample 1-1 and the silicone composition 1B' of the control sample 1-2 were two-component curing type curable oils and fats which were mixed and left to stand for about 24 hours to be cured, as described later.

Samples 5-1 and 5-2：

Sample 5-1 was mixed in the same manner as in sample 1-1 except that 1 part by weight of an alkyl quaternary ammonium clay (trade name: GARAMINE-7303, manufactured by BYK Additives & Instruments) was added as a thickening-inhibiting anti-settling agent 3 in place of the thickening-inhibiting anti-settling agent 1 in sample 1-1 to prepare a silicone composition 5A.

Sample 5-2 was mixed in the same manner as in sample 1-2 except that 1 part by weight of an alkyl quaternary ammonium clay (trade name: GARAMITE-7303, manufactured by BYK Additives & Instruments) was added in place of the thickening-inhibiting anti-settling agent 1 used in sample 1-2, to prepare a silicone composition 5B.

Samples 6-1 and 6-2：

Sample 6-1 was mixed in the same manner as in sample 1-1 except that 6 parts by weight of a cellulose powder (average particle diameter: 50 μm, angle of repose: 57 ℃) in the form of elongated particles was added as the thickening-inhibiting anti-settling agent 4 in place of the thickening-inhibiting anti-settling agent 1 used in sample 1-1, to prepare a silicone composition 6A.

Sample 6-2 was mixed in the same manner as in sample 1-2 except that 6 parts by weight of a cellulose powder (average particle diameter: 50 μm, angle of repose: 57 ℃) in the form of elongated particles was added as the thickening-inhibiting anti-settling agent 4 in place of the thickening-inhibiting anti-settling agent 1 used in sample 1-2, to prepare a silicone composition 6B.

Samples 7-1 and 7-2：

Sample 7-1 was mixed in the same manner as in sample 1-1 except that 6 parts by weight of a round cellulose powder (average particle diameter: 100 μm, angle of repose: 34 ℃) was added as the thickening-inhibiting anti-settling agent 5 in place of the thickening-inhibiting anti-settling agent 1 used in sample 1, to prepare a silicone composition 7A.

Sample 7-2 was mixed in the same manner as in sample 1-2 except that 6 parts by weight of a cellulose powder (average particle diameter: 100 μm, angle of repose: 34 ℃) in a round shape was added as the thickening-inhibiting anti-settling agent 5 in place of the thickening-inhibiting anti-settling agent 1 used in sample 1-2, to prepare a silicone composition 7B.

Samples 8-1 and 8-2：

Sample 8-1 was mixed in the same manner as in sample 1-1 except that 6 parts by weight of starch (corn starch) (average particle diameter: 500 μm, angle of repose: 48 °) was added as the thickening-inhibiting anti-settling agent 6 in place of the thickening-inhibiting anti-settling agent 1 used in sample 1-1, to prepare a silicone composition 8A.

Sample 8-2 was mixed in the same manner as in sample 1-2 except that 6 parts by weight of starch (corn starch) (average particle diameter: 500 μm, angle of repose: 48 °) was added as the thickening-inhibiting anti-settling agent 6 in place of the thickening-inhibiting anti-settling agent 1 used in sample 1-2, to prepare a silicone composition 8B.

Samples 9-1 and 9-2：

Sample 9-1 was mixed in the same manner as in sample 1-1 except that 6 parts by weight of chitosan (average particle diameter: 180 μm, angle of repose: 52 ℃) was added as the thickening-inhibiting anti-settling agent 7 in place of the thickening-inhibiting anti-settling agent 1 used in sample 1-1, to prepare a silicone composition 9A.

Sample 9-2 was mixed in the same manner as in sample 1-2 except that 6 parts by weight of chitosan (average particle diameter: 180 μm, angle of repose: 52 ℃) was added as the thickening-inhibiting anti-settling agent 7 in place of the thickening-inhibiting anti-settling agent 1 used in sample 1-2, to prepare a silicone composition 9B.

The silicone compositions 5A, 6A, 7A, 8A, 9A of the samples 5-1, 6-1, 7-1, 8-1, 9-1 and the silicone compositions 5B, 6B, 7B, 8B, 9B of the samples 5-2, 6-2, 7-2, 8-2, 9-2 were mixed and left to stand for about 24 hours to cure, respectively, as described below, to form two-component curing type curable oils and fats.

Sample No. 10-1：

Sample 10-1 was mixed in the same manner as in comparative sample 1-1 except that 1400 parts by mass of martensitic stainless steel (12.5% Cr, average particle size: 10 μm, specific gravity: 7.6) as a high specific gravity soft magnetic filler 1 and 200 parts by mass of spherical alumina 3 (average particle size: 70 μm, specific gravity: 3.94), 80 parts by mass of spherical α -alumina single crystal particles (average particle size: 0.5 μm, specific gravity: 3.94) having a substantially polyhedral shape and 40 parts by mass of aluminum hydroxide (average particle size: 1 μm, specific gravity: 2.4) were used as a medium specific gravity heat conductive filler, to prepare silicone composition 10A (base compound).

Sample No. 10-2：

Sample 10-2 was mixed in the same manner as in sample 10-1 except that 100 parts by mass of an organohydrogenpolysiloxane (specific gravity 1, trade name: KE-1012-B, manufactured by shin-Etsu chemical Co., Ltd.) having two or more H — Si groups at the end as an addition reaction type liquid silicone (specific gravity 1, product name: KE-1012-B) was prepared as liquid silicone 2 instead of liquid silicone 1 used in sample 10-1, and a platinum catalyst was not prepared, to prepare silicone composition 10B (curing agent).

The silicone composition 10A (main agent) of sample 10-1 and the silicone composition 10B (curing agent) of sample 10-2 are two-component curing type curable oils and fats which are mixed and left to stand for about 24 hours to be cured, as described later.

Sample No. 11-1：

Sample 11-1 was mixed in the same manner as in sample 1-1 except that 1400 parts by mass of martensitic stainless steel (12.5% Cr, average particle size: 10 μm, specific gravity: 7.6) as a high specific gravity soft magnetic filler 1 and 200 parts by mass of spherical alumina 3 (average particle size: 70 μm, specific gravity: 3.94), 80 parts by mass of spherical α -alumina single crystal particles (average particle size: 0.5 μm, specific gravity: 3.94) having a substantially polyhedral shape and 40 parts by mass of aluminum hydroxide (average particle size: 1 μm, specific gravity: 2.4) were used as a medium specific gravity heat conductive filler, to prepare a silicone composition 11A (base compound).

Sample No. 11-2：

Sample 11-2 was mixed in the same manner as in sample 11-1 except that 100 parts by mass of an organohydrogenpolysiloxane (specific gravity 1, trade name: KE-1012-B, manufactured by shin-Etsu chemical Co., Ltd.) having two or more H — Si groups at the end as an addition reaction type liquid silicone (specific gravity 1) was prepared as liquid silicone 2 instead of liquid silicone 1 used in sample 11-1, and a platinum catalyst was not prepared, to prepare silicone composition 11B (curing agent).

The silicone composition 11A (main component) of sample 11-1 and the silicone composition 11B (curing agent) of sample 11-2 are two-component curing type curable oils and fats which are mixed and left to stand for about 24 hours to be cured, as described later.

Sample No. 12-1：

Sample 12-1 was mixed in the same manner as in comparative sample 1-1 except that 1020 parts by mass of stainless steel (3.5% Si, 4.5% Cr, insulation coating treatment product, average particle diameter: 11 μm, specific gravity: 7.2) as a Fe-Si-Cr-based iron alloy was used instead of the high specific gravity soft magnetic filler 2, to prepare a silicone composition 12A (base compound).

Sample No. 12-2：

Sample 12-2 was mixed in the same manner as in sample 12-1 except that 100 parts by mass of an organohydrogenpolysiloxane (specific gravity 1, trade name: KE-1012-B, manufactured by shin-Etsu chemical Co., Ltd.) having two or more H — Si groups at the end as addition reaction type liquid silicone (specific gravity 1, product name: KE-1012-B) was prepared as liquid silicone 2 instead of liquid silicone 1 used in sample 12-1, and no platinum catalyst was added, to prepare silicone composition 12B (curing agent).

The silicone composition 12A (main component) of sample 12-1 and the silicone composition 12B (curing agent) of sample 12-2 are two-component curing type curable oils and fats which are mixed and left to stand for about 24 hours to be cured, as described later.

Sample No. 13-1：

Sample 13-1 was mixed in the same manner as in sample 11-1 except that 1020 parts by mass of stainless steel (3.5% Si, 4.5% Cr, insulation-coated product, average particle diameter: 11 μm, specific gravity: 7.2) as a Fe-Si-Cr-based iron alloy was used instead of the high specific gravity soft magnetic filler 2, to prepare a silicone composition 13A (base compound).

Sample No. 13-2：

Sample 13-2 was mixed in the same manner as in sample 13-1 except that 100 parts by mass of an organohydrogenpolysiloxane (specific gravity 1, trade name: KE-1012-B, manufactured by shin-Etsu chemical Co., Ltd.) having two or more H — Si groups at the end as addition reaction type liquid silicone (specific gravity 1, product name: KE-1012-B) was prepared as liquid silicone 2 instead of liquid silicone 1 used in sample 13-1, and a catalyst was not prepared, to prepare silicone composition 13B (curing agent).

The silicone composition 13A (main agent) of sample 13-1 and the silicone composition 13B (curing agent) of sample 13-2 are two-component curing type curable oils and fats which are mixed and left to stand for about 24 hours to be cured, as described later.

< various measuring methods, tests and evaluations >

Measurement of viscosity：

The viscosity (Pa. s) was measured at a measurement temperature of 23 ℃ at a rotation speed of 5rpm and 10rpm using a spindle of spindle No. SC4-14 using a viscometer (product name "BROOKFIELD rotational viscometer DV-E"). The results are shown in tables 1 to 3. In addition, in samples 10-1, 11-1, 12-1 and 13-1, only 10rpm of the rotation speed was measured, and the results are shown in Table 4.

Precipitation test and evaluation thereof:

the silicone compositions of samples 1-1 to 13-2 were filled in cylindrical containers having a diameter of 20mm and a height of 120mm to a height of 100mm, and left at rest in an environment of 60 ℃ for 1000 hours, and the state of precipitation of the filler was visually observed.

Then, the precipitation state of each sample was evaluated in 5 stages as shown below. The results are shown in tables 1 to 4.

5: completely unseparated state.

4: although not separated, the surface appeared to be smooth. (the state where the concentration of the liquid silicone on the surface was high and the granular sensation of the thermally conductive filler was small.)

3: although not separated, a thin film of liquid silicone covers the surface. (in a state where particles of the thermally conductive filler are not present on the surface.)

2: the separation is such that the liquid silicone flows out when the separation is inclined. (the liquid silicone is separated in a thickness of 1mm or more and less than 5 mm.)

1: the liquid silicone is separated in a thickness of 5mm or more.

Oil release degree：

With respect to the silicone compositions of samples 1-1 to 13-2, the silicone compositions were prepared according to JISK 2220: 2013 measure the oil release (%) after standing at 100 ℃ for 168 hours.

Thermal conductivity：

Regarding the silicone compositions of samples 1-1 to 13-2, the silicone composition ending in "-1" of the sample was designated as agent a, and the silicone composition ending in "-2" of the sample was designated as agent B, and the agent a and the agent B were mixed and left to stand at 25 ℃ for 24 hours to prepare respective cured grease mixed compositions of samples 1 to 13. Then, each composition was formed into a sheet having a thickness of 20mm to prepare a test piece for thermal conductivity measurement. For each test piece, thermal conductivity (W/m.K) was measured by a non-constant thin line heating method using a rapid thermal conductivity meter QTM-500 manufactured by Kyoto electronics industries, Ltd. The results are also shown in tables 1 to 4.

Absorption of electromagnetic waves：

Regarding the silicone compositions of the above-mentioned samples 1-1 to 9-2, the silicone composition ending with "-1" of the sample was designated as the agent a, and the silicone composition ending with "-2" of the sample was designated as the agent B, and the agent a and the agent B were mixed and left to stand at 25 ℃ for 24 hours to prepare the curable grease mixed compositions of the samples 1 to 9, respectively. Each composition was formed into a ring shape having an outer diameter of 20mm, an inner diameter of 5mm and a thickness of 8mm to prepare a test piece for magnetic permeability measurement. The relative permeability μ' of the magnetic permeability measurement test piece at a frequency of 1MHz to 1GHz was measured using an impedance material analyzer E4991A (manufactured by Keysight) and a magnetic material measuring electrode 16454A (manufactured by Keysight). Tables 1 to 3 show the relative permeability at 10 MHz.

On the other hand, regarding the silicone compositions of the above-mentioned samples 10-1 to 13-2, the silicone composition ending with "-1" of the sample was referred to as agent a, and the silicone composition ending with "-2" of the sample was referred to as agent B, and the agent a and the agent B were mixed and left to stand at 25 ℃ for 24 hours to prepare mixed compositions of the curable fats and oils of the samples 10 to 13, respectively. Then, each composition was formed into a ring shape having an outer diameter of 7mm, an inner diameter of 3mm, and a thickness of 1mm to prepare a test piece for magnetic permeability measurement. The relative permeability μ' of the magnetic permeability measuring test piece at a frequency of 100MHz to 18GHz was measured using a vector network analyzer E5071A (manufactured by Keysight corporation) and a coaxial sample holder CSH2-APC7 (manufactured by kanto electronic application and development) as a magnetic material measuring electrode. The relative permeability at 10GHz is shown in table 4.

[ TABLE 1 ]

[ TABLE 2 ]

[ TABLE 3 ]

[ TABLE 4 ]

< analysis of test results >

From the results of samples 3-1 to 4-2, when silica powder was used as the non-liquid thickening-inhibiting anti-settling agent, the viscosity increased, and the viscosity could not be measured when the amount of addition was large. The viscosity of the silicone composition immediately after the preparation showed a viscosity lowering effect in samples 1-1 to 2-2 and 6-1 to 9-2, compared with the viscosity of control samples 1-1 and 1-2. The samples 5-1 to 5-2 exhibited a slight viscosity increasing effect.

As to the effect of suppressing precipitation, it is understood that all of the samples 1-1 to 9-2 to which the thickening-inhibiting anti-settling agent was added had the effect of suppressing precipitation, considering the results of the precipitation states of the control samples 1-1 and 1-2.

As for the thermal conductivity, the two-component curable oils and fats obtained from the mixtures of samples 1-1 to 9-2 exhibited thermal conductivities comparable to those of the two-component curable oils and fats obtained from the mixtures of control samples 1-1 and 1-2 to which no thickening inhibitor was added, even when the thickening inhibitor was added.

It is found that the two-component curable type curable oil-and-fat obtained from the mixture of each of samples 1-1 to 3-2 and 6-1 to 9-2 exhibits a relative permeability comparable to that of the two-component curable type curable oil-and-fat obtained from the mixture of control samples 1-1 and 1-2 to which no thickening inhibitor is added, even when the thickening inhibitor is added. Further, when the two-component curable grease obtained from the mixture of samples 3-1 and 3-2 and the two-component curable grease obtained from the mixture of samples 4-1 and 4-2 were compared, it was found that the relative permeability decreased when the amount of the gas-phase mixed oxide added was too large. It is also found that the two-component curable type curable grease obtained from the mixture of samples 5-1 and 5-2 has a slightly lower relative permeability than the two-component curable type curable grease obtained from the mixture of control samples 1-1 and 1-2 to which no thickening inhibitor was added.

From the results of samples 10-1 to 13-2, it is found that when a martensitic stainless steel, which is an Fe-Cr system iron alloy having a larger specific gravity than the soft magnetic Ni-Zn ferrite, or a stainless steel, which is an Fe-Si-Cr system iron alloy, is used as the high specific gravity soft magnetic filler, the entire viscosity becomes high, and therefore separation is difficult to occur, and therefore the oil release degree becomes a small value, and precipitation of the filler does not occur significantly. However, it was found that by adding a thickening-inhibiting anti-settling agent, a composition free from settling can be obtained in a state in which the viscosity is slightly reduced, the viscosity does not increase, the oil release is reduced, the separation is difficult, and the separation is not achieved at all even in a settled state. From this fact, it is found that even when an iron alloy having a higher specific gravity than that of the soft magnetic Ni — Zn ferrite is used as the high specific gravity soft magnetic filler, if a thickening-inhibiting anti-settling agent is added, the precipitation of the high specific gravity soft magnetic filler and the medium specific gravity thermal conductive filler having a higher specific gravity than that of the liquid silicone in the silicone composition can be inhibited. Further, it is known that the thermal conductivity and the relative magnetic permeability do not change particularly greatly even if a thickening inhibitor is added.