JP3504882B2 - Thermally conductive and electrically insulating silicone composition and silicone molding using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silicone composition having thermal conductivity and electrical insulation,
A heat conductive / electrically insulating silicone composition used as a heat conductive part such as an electric part, a part for electric insulation, and the like.
The present invention relates to a silicone molded product .

[0002]

2. Description of the Related Art Electronic parts such as transistors, diodes and transformers generate heat when they are used, and the heat may deteriorate the performance of the electronic parts. Therefore, a radiator is attached to the electronic components that generate heat. However, since the heat radiator is often made of metal, it is not preferable to directly mount the electronic component because of problems such as electric leakage. Therefore, it has been used by sandwiching mica insulating plate, heat conductive grease, polyester, etc. between the electric parts and the radiator, but it is difficult to handle and has low thermal conductivity, and it has satisfactory performance. It wasn't a thing. In order to improve these, as proposed in Japanese Patent Publication No. 19525/1982, rubber has a thermal conductivity such as boron nitride.
There is an example in which an electrically insulating filler is added to improve the thermal conductivity. Recently, in order to improve the adhesion between the heat generating element and the radiator, a gel type, which has a considerably low rubber hardness, as proposed in JP-A-6-155517, has been widely used.

[0003]

However, in recent years, due to the miniaturization and high integration of electric circuits and the high heat generation of the heat generating element itself, even if a heat conductive silicone gel composition is used, no heat countermeasure can be taken. The cases are increasing. Therefore, there are quite a few cases in which the grease reverts to being used a long time ago and grease is used. However, there is a problem that the grease is difficult to handle.

In order to solve the above-mentioned conventional problems, the present invention deals with a heat-conductive / electrically-insulating silicone composition which is about the same as a heat-conductive silicone gel currently on the market and has thermal properties comparable to grease, and Silicone molding used
It is to provide things .

[0005]

In order to achieve the above object, the heat conductive / electrically insulating silicone composition of the present invention contains the following silicone resins A and B, wherein the silicone resin B is 100 parts by weight. 1 to 1 of silicone resin A
A varnish mixed at a ratio of 000 parts by weight was prepared, and 5 parts by weight of the thermally conductive filler (component C) was added to 100 parts by weight of the varnish.
It is characterized in that the compound is a mixture of ˜1200 parts by weight. Silicone resin A: Silicone resin having a three-dimensional stitch structure, which is solid at room temperature and has a heat softening temperature of 60 to 115 ° C.
Range of thermoplastic silicone resins. Silicone resin B: A wax-like silicone resin which is a linear alkyl-modified silicone having a structural formula represented by the following formula (Formula 2).

[0006]

[Chemical 2]

[0007] By doing so, a heat conductive / electrically insulating silicone composition which is handled at the level of the currently commercially available heat conductive silicone gel and has thermal characteristics similar to those of grease, and a product using the same are provided. can do.

In the silicone composition, it is preferable to further mix the following components D to I in the following composition ratio with respect to 100 parts by weight of the varnish. Component D: Heat storage material 0-600 parts by weight Component E: Plasticizer 0-30 parts by weight Component F: Reinforcing agent 0-50 parts by weight Component G: Platinum-based compound 0-10 parts by weight Component H: Silane coupling agent 0- 10 parts by weight Component I: Vulcanizing agent 0 to 10 parts by weight

[0009] The silicone moldings of the present invention, also the formation of the silicone composition into a film or sheet
Of. The film shape or the sheet shape is convenient, for example, to be sandwiched between the heat generating element and the heat absorber. Film or sheet moldings are extruded moldings,
It can be formed by a solventless coated molded product or a dispersion coated molded product.

Further, it is preferable that the silicone molded product is solid at room temperature and is softened when the heat generating element is operating so that the space between the heat generating element and the heat absorber is filled without any gap. For example, the thermally conductive / electrically insulating silicone molded product is solid at room temperature for easy handling, and is softened when the heat generating element is operating to fill the gap between the heat generating element and the heat absorbing body without any gap. At the same time, since the thickness of the thermally conductive / electrically insulating silicone molding between the heat generating element and the heat absorber is considerably thin, the thermal resistance value can be considerably reduced.

The silicone molded product preferably has a viscosity when softened in the range of 500 to 1,000,000 cP. The silicone molded product preferably has a pressure-sensitive adhesive layer formed on the surface of the film-shaped or sheet-shaped molded product.

The silicone molded product is preferably processed into a film or a sheet by laminating a heat conductive silicone composition and a knitted fabric, a film or a metal foil. For example, the thermally conductive / electrically insulating silicone composition can be made into a thermally conductive silicone composition, a knitted woven fabric, a film, a metal foil and a two-layer or three-layer sheet, or a film. In particular, when applied to a glass cloth reinforced thermally conductive silicone molded product having a rough surface, the effect of further reducing the thermal resistance value can be obtained.

Further, it is preferable that a release paper or a release film is attached to the surface of the silicone molded product as a carrier. For example, in the case of a thermally conductive / electrically insulating silicone molded product , a release paper or a release film can be used as a carrier, which can facilitate post-processing such as profile punching. Also,
By selecting the release paper or the release film, the release can be easily performed, so that the handling can be considerably simplified.

Further, the silicone molded product is preferably a film-shaped or sheet-shaped product wound into a reel. In this way, the assembly process can be automated.

[0015]

Embodiments of the present invention will be described below. The heat conductive / electrically insulating silicone composition of the present invention is a silicone resin having a three-dimensional stitch structure at room temperature with respect to 100 parts by weight of the wax-like linear alkyl-modified silicone represented by the formula (Formula 2). Then, it is solid and mixed with 1 to 1000 parts by weight of a thermoplastic silicone resin having a heat softening temperature of 60 to 115 ° C. to form a varnish, and at least Component C is added and mixed to 100 parts by weight of the varnish, preferably It is constituted by adding and mixing the components D to I in the following composition ratios. Component C: Thermally conductive filler 5 to 1200 parts by weight Component D: Heat storage material 0 to 600 parts by weight Component E: Plasticizer 0 to 30 parts by weight Component F: Reinforcing agent 0 to 50 parts by weight Component G: Platinum-based compound 0 10 parts by weight Component H: 0 to 10 parts by weight of silane coupling agent Component I: 0 to 10 parts by weight of vulcanizing agent

The silicone resin having a three-dimensional stitch structure is preferably a thermoplastic silicone resin which is solid at room temperature and has a heat softening temperature in the range of 60 to 115 ° C.

In the wax-like linear alkyl-modified silicone represented by the above formula (Formula 2), a in the structural formula is 20 to 4
It is preferably in the range of 0, more preferably 26 to 3
The range is 5. R includes an alkyl group having 1 to 6 carbon atoms, a hydroxyl group, an amino group, a carboxyl group, a phenyl group, a vinyl group, a trifluoromethyl group, and the like, and a methyl group is preferable. The melting point is preferably about 50 ° C. If it is too low, handling of the product will be poor in the summer, which is a problem.

A silicone resin having a three-dimensional stitch structure, which is solid at room temperature and has a heat softening temperature of 60 to 11, based on 100 parts by weight of a wax-like linear alkyl-modified silicone.
The thermoplastic silicone resin in the range of 5 ° C is 1 to 100
It is preferable to mix 0 parts by weight. Here, when the softening temperature of the product itself is raised, it is a silicone resin having a three-dimensional stitch structure, which is solid at room temperature and has a thermal softening temperature of 60.
The blending ratio of the thermoplastic silicone resin in the range of ˜115 ° C. may be increased, and when the softening temperature is lowered, the blending ratio is decreased. A thermoplastic silicone resin having a three-dimensional structure and being solid at room temperature and having a heat softening temperature in the range of 60 to 115 ° C. must be added to maintain the shape of the product.

The thermally conductive filler to be added includes aluminum nitride, boron nitride, silicon nitride, etc. as the nitride, silicon carbide, titanium carbide, boron carbide, etc. as the carbide, and basic metal oxide as the metal oxide. Are aluminum oxide, magnesium oxide, zinc oxide, calcium oxide, zirconium oxide and the like, and if the above-mentioned filler is used, one kind or a mixture of two or more kinds is also suitably used.

The particle shape of these thermally conductive fillers may be either spherical or flaky. The weight average particle diameter is preferably in the range of 0.5 to 100 μm. The ratio of the basic metal oxide to the nitride or the carbide is preferably 0 to 120 parts by weight with respect to 1 part by weight of the nitride or the carbide.

Further, the combination of a nitride or a carbide and a basic metal oxide includes one kind of a basic metal oxide such as boron nitride and aluminum oxide, one kind of a nitride or a carbide, or boron nitride and an aluminum oxide, or an oxide. Like magnesium, two kinds of basic metal oxides and one kind of nitride or carbide may be used, or various combinations such as nitride and carbide alone may be used.

The basic metal oxide may be treated with a silane coupling agent. Examples of the coupling agent include a silane coupling agent, a titanium coupling agent, and an aluminum coupling agent, and any of them may be used. The preferred amount of the coupling agent added is 0.
It is from 05 to 2% by weight. Examples of the silane coupling agent include γ-methacryloxypropyltrimethoxysilane.

Further, with respect to 100 parts by weight of the wax-like linear alkyl-modified silicone represented by the above formula (Formula 2), it is a silicone resin having a three-dimensional stitch structure and is solid at room temperature and has a heat softening temperature of 60. The addition amount of the heat conductive filler is 5 to 100 parts by weight of the varnish mixed with 1 to 1000 parts by weight of the thermoplastic silicone resin in the range of to 115 ° C.
1200 parts by weight is preferred.

The heat storage body includes paraffin type, nitrate type, acetate type, thiosulfate type and the like, and one kind or a mixture of two or more kinds is preferably used. Examples of paraffins include liquid paraffin, nitrates such as sodium nitrate, and acetates such as sodium acetate.
Examples of the thiosulfate system include sodium thiosulfate.

A typical example of the plasticizer is silicone oil, which may be added if necessary. Specific examples include dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, fluorosilicone oil and modified silicone oil.

Reinforcing agents include reinforcing silica, quartz, calcium carbonate, polytetrafluoroethylene and the like, which may be added if necessary.

The present invention relates to chloroplatinic acid for imparting flame retardancy,
One or a mixture of two or more platinum compounds such as alcohol-modified chloroplatinic acid, platinum olefin complex, methylpolyvinylsiloxane platinum complex and the like are preferably used. Further, as the flame retardant aid, there are iron oxide, titanium oxide, carbon black, aluminum hydroxide, magnesium hydroxide and the like, and one kind or a mixture of two or more kinds is preferably used.

The vulcanizing agent of the present invention may be vulcanized with a thermally conductive / electrically insulating silicone composition if necessary.
At this time, the vulcanization can be easily performed by using a vulcanizing agent used for vulcanizing a general silicone rubber.

The above-mentioned thermally conductive / electrically insulating silicone composition is preferably processed into a sheet or film so that it can be used by being sandwiched between a heating element and a heat absorber. Sheet and film molding can be processed by extrusion molding, solventless coating, and dispersion coating. A coating is preferable, and a solventless coating is particularly preferable because it is liquid when heated.

The pressure-sensitive adhesive applied to the above-mentioned thermally conductive / electrically insulating silicone sheet is preferably a silicone-based pressure-sensitive adhesive. Further, tackiness may be imparted by utilizing the viscosity of high-viscosity silicone oil.

[0031]

EXAMPLES The present invention will be described in more detail with reference to the following examples. (Example 1) 10 parts by weight of a silicone resin having a three-dimensional knit structure and the straight chain alkyl-modified silicone of the above formula (Formula 2), wherein a is 27, R is a methyl group, m is 25, and n is A varnish was prepared by mixing 90 parts by weight of the wax-like silicone resin of No. 5 above. A thermally conductive and electrically insulating silicone composition was prepared by adding 200 parts by weight of alumina to 100 parts by weight of this varnish. Toluene: 30 parts by weight was added to 100 parts by weight of this composition and dissolved, and polyethylene terephthalate (P
ET) coated on a film. Then, it was dried to prepare a film-like thermally conductive and electrically insulating silicone sheet having a thickness of 0.25 mm.

Example 2 Alumina 2 was added to 100 parts by weight of the varnish produced in Example 1.
A thermally conductive and electrically insulating silicone composition was prepared by adding 00 parts by weight and 30 parts by weight of sodium nitrate. This was applied onto a PET film in the same manner as in Example 1 and dried. As a result, a film-like thermally conductive / electrically insulating silicone sheet having a thickness of 0.25 mm could be prepared.

Example 3 A varnish was prepared by blending 30 parts by weight of a silicone resin having a three-dimensional stitch structure and 70 parts by weight of the linear alkyl-modified silicone resin of the formula (Formula 2) used in Example 1. To 100 parts by weight of this varnish, 200 parts by weight of alumina and 30 parts by weight of sodium nitrate were added to prepare a heat conductive / electrically insulating silicone composition. This was dissolved in toluene, coated on a PET film with a doctor plate, and dried. As a result, a film-like thermally conductive / electrically insulating silicone sheet having a thickness of 0.25 mm could be prepared.

Example 4 A varnish containing 30 parts by weight of a silicone resin having a three-dimensional stitch structure and 70 parts by weight of a linear alkyl-modified silicone resin of the formula (Formula 2) used in Example 1 was added to 200 parts by weight of alumina. Part, and 30 parts by weight of sodium nitrate were added to prepare a thermally conductive and electrically insulating silicone composition. This was dissolved in toluene, coated on PET with a doctor plate, and dried. As a result, a film-like thermally conductive / electrically insulating silicone sheet having a thickness of 0.25 mm could be prepared. One side of this sheet was treated with an adhesive to give tack.

Example 5 A varnish containing 30 parts by weight of a silicone resin having a three-dimensional stitch structure and 70 parts by weight of a straight chain alkyl-modified silicone resin of the formula (Formula 2) used in Example 1 was mixed with alumina : 200
A thermally conductive and electrically insulating silicone composition was prepared by adding 30 parts by weight of sodium nitrate. This was dissolved in toluene and coated on a glass cloth with a doctor plate. As a result, a film-like thermally conductive / electrically insulating silicone sheet having a thickness of 0.25 mm could be prepared.

(Comparative Example 1) 100 parts by weight of a liquid silicone elastomer "SH-4" (manufactured by Toray Dow Corning Silicone Co., Ltd.) was mixed with 30 parts by weight of aluminum oxide to prepare a liquid heat conductive grease. It was created.

Comparative Example 2 A compound was obtained by adding 300 parts by weight of aluminum oxide to 100 parts by weight of a liquid silicone elastomer "JCR6101" (manufactured by Toray Dow Corning Silicone Co., Ltd.) and kneading. This compound was coated on a glass cloth with a doctor plate and vulcanized to prepare a heat conductive silicone gel tape.

The results of Examples 1 to 5 and Comparative Examples 1 and 2 are summarized in Table 1.

[0039]

[Table 1]

From the above Table 1, the sheets prepared from the thermally conductive / electrically insulating silicone composition of the embodiment of the present invention are heat conductive / electrically insulating silicone compositions utilizing the heat of the heating element. Because of the softening, the adhesion between the heat generating element and the heat absorber is considerably improved, and the heat is efficiently transferred. Therefore, the thermal resistance value is considerably reduced. Moreover, since it is solid when heat is not applied, it is easy to handle (handle).

On the other hand, in Comparative Example 1, since it is a grease, the handling property is inferior. In Comparative Example 2, a heat-generating element and a heat-absorbing body are used as compared with the sheet produced from the thermally conductive / electrically insulating silicone composition of the present invention. The adhesiveness of
The thermal resistance value was large.

[0042]

As described above, according to the present invention, a silicone composition having high thermal conductivity and electrical insulation is obtained, and a product obtained by molding the silicone composition into a sheet, a film or the like has excellent handleability. It is possible to provide a heat conductive / electrically insulating silicone molded product having excellent thermal characteristics as good as grease. Also,
Roughness of the product surface can be absorbed by applying the above-mentioned thermally conductive and electrically insulating silicone molded product sheet to thermally conductive silicone rubber reinforced with glass cloth, etc.
Further, the efficiency of heat conduction can be improved.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI H01B 3/46 H01B 3/46 G 17/56 17/56 A // (C08L 83/04 C08L 83:08 83:08) ( 56) Reference JP 10-110179 (JP, A) JP 11-246884 (JP, A) JP 51-55870 (JP, A) JP 50-105573 (JP, A) JP 10-67910 (JP, A) JP 2000-63873 (JP, A) JP 2000-109373 (JP, A) JP 11-49958 (JP, A) JP 3-162493 (JP, A) ) JP-A-4-328163 (JP, A) JP-A-1-215855 (JP, A) JP-A-10-189838 (JP, A) JP 2000-509209 (JP, A) US Pat. A) US Pat. No. 5,904,966 (US, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 83/00-83/16 H01B 3/46 H01B 17/56 C10M 16 9/00-169/06 CA (STN) REGISTRY (STN)

Claims (10)

(57) [Claims] 1. A silicone resin comprising the following silicone resins A and B:
A silicone resin B is mixed in a proportion of 1 to 1000 parts by weight with respect to 100 parts by weight of the silicone resin B, and 5 to 1200 parts by weight of a thermally conductive filler (component C) is mixed into 100 parts by weight of the varnish. A thermally conductive and electrically insulating silicone composition, characterized in that it is a compound. Silicone resin A: a thermoplastic silicone resin which has a three-dimensional stitch structure, is solid at room temperature, and has a heat softening temperature in the range of 60 to 115 ° C. Silicone resin B: a wax-like silicone resin which is a linear alkyl-modified silicone represented by the following formula (Formula 1). [Chemical 1] 2. The heat conductive / electrically insulating silicone composition according to claim 1, wherein 100 parts by weight of the varnish are further mixed with the following components D to I at the following composition ratios. Component D: Heat storage material 0-600 parts by weight Component E: Plasticizer 0-30 parts by weight Component F: Reinforcing agent 0-50 parts by weight Component G: Platinum-based compound 0-10 parts by weight Component H: Silane coupling agent 0- 10 parts by weight Component I: Vulcanizing agent 0 to 10 parts by weight Wherein the silicone composition according to claim 1 or 2 is formed into a film or sheet
A silicone molded product characterized by: 4. The silicone molded product according to claim 3, wherein the film or sheet molded product is at least one selected from an extrusion molded product, a solventless coating molded product and a dispersion coating molded product . 5. The silicone molded product according to claim 3, which is solid at room temperature and is softened when the heating element is operating to fill the gap between the heating element and the heat absorber without any gap. 6. The softening viscosity is 500 to 1,000,0.
The silicone molding according to claim 5, which is in the range of 00 cP.
Thing . 7. The series according to claim 3, wherein a pressure-sensitive adhesive layer is formed on the surface of the film-shaped or sheet-shaped molded product.
Cone moldings . 8. A film formed by laminating a thermally conductive silicone composition and a knitted cloth, film or metal foil,
Sheet according to any one of claims 3-7 which was processed into a sheet
Recone molding . 9. The silicone molded product according to claim 3 , wherein a release paper or a release film is adhered to the surface as a carrier. 10. The silicon dioxide according to claim 3, wherein the film-shaped or sheet-shaped material is wound into a reel.
Molded product .