JPS6314444B2 - - Google Patents

Description

[Detailed description of the invention]

A. Industrial technical field The present invention relates to a novel thermally conductive material having electrical insulation properties and a method for manufacturing the same. B. Summary of the Invention The present invention relates to a novel thermally conductive material that is electrically insulating and has good thermal conductivity. C. Prior art Thermal conductive materials that have electrical insulation properties include mica board, aluminum oxide, mylar board (polyethylene terephthalate film), beryllium oxide,
Boron nitride has been used. Since these materials lack flexibility, they may break during processing or cause dielectric breakdown. Furthermore, in order to improve contact, it was necessary to use heat dissipating grease. In response to this, recently a thermally conductive material made by kneading boron nitride into silicone rubber has been developed as a thermally conductive material that is flexible and has electrical insulation properties. D. Problems to be Solved by the Invention However, this material does not necessarily have sufficient properties in other respects and has the following problems. That is, (1) a large amount of inorganic filler is mixed, resulting in a decrease in flexibility. (2) Because the polymer is two-dimensionally bonded, mechanical strength is low and elongation is low. (3) Electrical insulation cannot be improved. (4) Material costs are high. That is what it is. E. Means for Solving the Problems The inventors worked to develop a new thermally conductive material that is electrically insulating and has good thermal conductivity. A thermally conductive electrical insulating material comprising a polymer made of resin, a crosslinking agent of organometallic alkoxide, and an inorganic filler of aluminum oxide or aluminum hydroxide has been achieved. F Function The thermally conductive electrical insulating material of the present invention consists of a polymer serving as a base material of the material, an organometallic alkoxide crosslinking agent, and an inorganic filler. −
Thermoplastic resins with OH groups, e.g. It is preferable to use On the other hand, as a crosslinking agent to be used separately, it is effective to use an organometallic alkoxide in which a metal is bonded to an alkoxy group, which is a monovalent atomic group in which oxygen is bonded to the terminal of an alkyl group, and the general formula is: Al(OR) ₃ , Ti(OR) ₄ , Zr(OR) ₄ or Ge
(OR) ₄ (R is C ₁ to C ₄ -CH ₃ , -C ₂ H ₅ , -C ₃ H ₇ , -
Examples include alkyl groups consisting of C ₄ H ₉ or phenyl groups). Specifically, Al(OCH(CH3) ₂ ) ₃ , _Al
( _OC4H9 ) ₃ , Al _{( OC2H5} ) _{3 ,} Ti( _OC4H9 ) _{4 ,} Zr
(OC ₄ H ₉ ) ₄ etc. were proved to be effective according to the embodiments of the present invention. In this invention, an inorganic filler is added to the product obtained by crosslinking the above-mentioned polymer with an organometallic alkoxide. Or aluminum hydroxide is preferable. In constructing a thermally conductive electrically insulating material according to the present invention, each component can be blended in the following ratio. That is, it is preferable that the thermoplastic resin polymer having an -OH group in its molecular chain be present in an amount of 20 to 49% by weight in the thermally conductive electrical insulating material. Furthermore, if the amount of organometallic alkoxide used as a crosslinking agent is less than 1% (by weight), sufficient strength will not be obtained due to insufficient crosslinking, whereas if it exceeds 10% (by weight), excessive crosslinking will often occur. Therefore, amounts within the range of approximately 1 to 10% by weight are generally used. As for inorganic fillers, their content is 50% by weight
If the amount is less than 50 to 80% by weight, sufficient thermal conductivity cannot be obtained, and if the amount exceeds 80% by weight, it becomes difficult to sufficiently knead the reaction product of the polymer and the organometallic. It is preferable that By blending each in accordance with the above-mentioned grounds, a highly thermally conductive electrically insulating material with electrically insulating properties capable of exhibiting the desired effects can be obtained. The thermally conductive electrical insulating material of the present invention is produced by charging a polymer such as polyvinyl alcohol, polyvinyl butyler, or phenoxy resin in an amount equivalent to 20 to 49% by weight into a reaction vessel through which nitrogen gas is passed, depending on the properties of the polymer. , heat and melt at 100 to 220°C, and gradually add an organic metal alkoxide such as Ti(OR) ₄ , Al(OR) ₃ , Ge(OR) ₄ or the like in an amount equivalent to 1 to 10% by weight as a crosslinking agent while stirring. Let it react for 20-30 minutes. In this case, if the amount of crosslinking agent added exceeds 10%, for example, about 15% (by weight), the reaction product will become gelled due to excessive crosslinking, which is not preferable. Next, the reaction product is taken out from the reaction vessel, and the reaction product and the aforementioned aluminum oxide or aluminum hydroxide are charged into a conventional kneader together with 50 to 80% by weight at 110 to 220°C for 10 to 20 minutes. A molding material is obtained by kneading. This product is molded into the desired shape using a known molding machine.
Specifically, it is possible to manufacture a thermally conductive electrical insulating material by molding it into a sheet having an appropriate thickness using, for example, calendering equipment. G. Examples Hereinafter, the manufacturing method and characteristic values of the thermally conductive electrically insulating material of the present invention will be described with specific examples. Example 1 Polyvinyl butyral (electrochemistry: Denka Butyral #2000L) 30% by weight,
Commercially available Al〔OCH
5% by weight of (CH ₃ ) ₂ ] ₃ and aluminum hydroxide (Showa Light Metal Hygilite H) as inorganic filler.
-231) was prepared, and Denka Butyral #2000L was put into a reaction vessel through which nitrogen gas was passed, and the Al
[OCH(CH ₃ ) ₂ ] ₃ was gradually added and the reaction was carried out for about 30 minutes. Next, the reaction product was taken out and put into a pressure kneader together with Hygilite H-321 as an inorganic filler,
Kneading was carried out at 150° C. and a pressure of 5 kg/cm ² for 10 minutes. After kneading, a 0.3 mm thick sheet was created using calender equipment (manufactured by Nippon Roll, 14 inch inverted L type).
The characteristic values as a thermally conductive material were determined and are shown in Table 1. Example 2 25% by weight of polyvinyl alcohol (Poval C-17 manufactured by Shin-Etsu Chemical Co., Ltd.) was used as a polymer to serve as a base material, 5% by weight of commercially available Al(OC ₄ H ₉ ) ₃ as an organometallic alkoxide, and aluminum oxide ( A material consisting of 70% by weight of AL-13 (manufactured by Showa Light Metal) was prepared. Shin-Etsu Bobal C-17 was placed in a reaction vessel through which nitrogen gas was passed in the same manner as in Example 1, and Al(OC ₄ H ₉ ) ₃ was gradually added while stirring under pressure at 110°C, and the reaction was continued for about 20 minutes. After that, it was charged into a pressure kneader together with aluminum oxide and kneaded for 10 minutes at 130°C. A sheet was prepared in the same manner as in Example 1, and its characteristic values as a thermally conductive material were determined. are shown in Table 1. Example 3 Same as Example 1 using 35% by weight of phenoxy resin (manufactured by Union Carbide Co., USA) as the base polymer, 5% by weight of commercially available Al(OC ₂ H ₅ ) ₃ as the organometallic alkoxide, and the same as in Example 1 as the inorganic filler. Components with a blending ratio of 60% by weight of aluminum oxide were put into a reaction vessel through which nitrogen gas was passed, similar to that in Example 1, and heated and melted at 200°C, and the organometallic alkoxide was gradually added while stirring. After carrying out the reaction for about 30 minutes, the reaction product together with aluminum oxide was charged into a pressure kneader similar to that in Example 1, and
After kneading at ℃ for 15 minutes, a sheet was prepared in the same manner as in Example 1, and its characteristic values as a thermally conductive material were determined.
The results are shown in Table 1. Example 4 25% by weight of polyvinyl alcohol (Electrochemical Denka Poval K-17) as a polymer, Ti (OC ₄ H ₉ ) ₄ (Nippon Soda B-1) as an organometallic alkoxide
5% by weight and 70% by weight of aluminum hydroxide (Showa Light Metal AL-13) as an inorganic filler. The organic metal alkoxide Ti(OC ₄ H ₉ ) ₄ was gradually added in an amount equivalent to 5% by weight while melting and stirring at 130°C. After stirring for about 30 minutes, the reaction product was taken out and mixed with aluminum hydroxide (70% by weight) in Example 1.
The mixture was placed in a pressure kneader similar to the above, and kneaded at 150°C for 15 minutes. After kneading, a sheet was prepared in the same manner as in Example 1, and its characteristic values as a thermally conductive material were determined. The results are shown in Table 1. Example 5 The polymer was the same polyvinyl butyral 30 weight 5 as in Example 1, and Zr as the organometallic alkoxide.
(OC ₄ H ₉ ) ₄ (Nippon Soda TBZR) 5% by weight, and the same inorganic filler as in Example 2, 65% by weight of aluminum oxide, and the polyvinyl butyral (30% by weight) as in Example 1. Pour into a similar reaction vessel through which nitrogen gas is passed, melt at 150℃,
While stirring, 5% by weight of Zr(OC ₄ H ₉ ) ₄ was gradually added. After about 30 minutes of reaction, the product was taken out and put into the same pressure kneader as in Example 1 together with 65% by weight of aluminum oxide and kneaded at 180°C for 15 minutes.
A sheet was prepared in the same manner as above, and its characteristic values as a thermally conductive material were determined. The results are shown in Table 1. Comparative Example 1 A reaction vessel was prepared in which the same polyvinyl alcohol as in Example 4 was passed through nitrogen gas as in Example 1, with the intention of producing 15% by weight of polymer, 15% by weight of organometallic alkoxide, and 70% by weight of inorganic filler. Pour the equivalent of 15% by weight of the material into the container, and while melting and stirring at 120℃, form the organic metal alkoxide.
Gradually drop Al(OCH(CH3) ₂ ) _{3 to} 10% by weight of the material.
After adding the same amount for 10 minutes, we investigated the reaction situation and found that it was impossible to make a sheet because it had turned into a gel. Comparative Example 2 A reaction vessel in which the same polyvinyl butyral as in Example 1 was used as the polymer and nitrogen gas was passed through it as in Example 1 was used to prepare a product with 15% by weight of polymer, 15% by weight of organometallic alkoxide, and 20% by weight of inorganic filler. Pour the equivalent of 15% by weight of the material into the container and melt at 130℃.
Al as organometallic alkoxide while stirring
(OC ₄ H ₉ ) ₃ was gradually added dropwise to add 15% by weight of the material over a period of 10 minutes, and the reaction status was examined. As a result, it was found that the mixture had become gelatinous, making it impossible to prepare a sheet. Comparative Example 3 It was planned to produce a product with the same composition as Comparative Examples 1 and 2, so the same phenoxy resin as in Example 3 was placed in a reaction vessel in which nitrogen gas was passed as in Example 1.
Al(OC ₂ H ₅ ) ₃ was added as an organometallic alkoxide and melted at 200°C with stirring.
After gradually adding the equivalent of 15% by weight over 15 minutes, the reaction status was examined and it was found that it had turned into a gel, making it impossible to make a sheet. The following Table 1 shows the characteristic values of the sheets as thermally conductive electrical insulating materials prepared in Examples 1 to 5 above and comparative values of conventional materials made of silicone rubber kneaded with boron nitride or the like. In Table 1, the compositions of Conventional Examples 1 and 2 are as follows. Conventional example 1 Silicone rubber 35wt% Alumina oxide 65wt% Conventional example 2 Silicone rubber 30wt% Boron nitride 70wt%

[Table] H Effects of the Invention As is clear from the above-mentioned Table 1, the thermally conductive electrical insulating material according to the present invention has a three-dimensional network structure formed by crosslinking a polymer with an organometallic alkoxide. The electrical dielectric strength, mechanical strength, and elongation of the material are improved, and the material is less expensive than silicone rubber and boron nitride-based thermally conductive materials.

Claims (1)

[Claims] 1. 20 to 49% by weight of a thermoplastic resin polymer having -OH groups in its molecular chain, 1 to 10% by weight of an organometallic alkoxide crosslinking agent, and an inorganic material such as aluminum oxide or aluminum hydroxide. 50-80 fillings
% by weight. 2. The thermally conductive electrically insulating material according to claim 1, wherein the polymer is made of polyvinyl alcohol, polyvinyl butyral, or phenoxy resin. 3 The organometallic alkoxide is Al(OR) ₃ , Ti
(OR) ₄ , Zr(OR) ₄ or Ge(OR) ₄ , and R in the molecular formula is a C ₁ to C ₄ alkyl group or a phenyl group, according to claim 1 thermally conductive electrical insulation material. 4 A type of polymer consisting of a thermoplastic resin having an -OH group in the molecular chain selected from polyvinyl alcohol, polyvinyl butyral, or phenoxy resin is heated and melted in a reaction vessel through which nitrogen gas is passed, and while stirring, Al(OR) is formed. ₃ , Ti(OR) ₄ , Zr(OR) ₄ , or Ge(OR) ₄ (wherein R in the molecular formula is a _C1 to _C4 alkyl group or phenyl group) is reacted by addition. 1. A method for producing a thermally conductive electrical insulating material, which comprises pressurizing and kneading a reaction product and aluminum oxide or aluminum hydroxide together. 5. The method for producing a thermally conductive electrically insulating material according to claim 4, wherein the reaction temperature between the organometallic alkoxide and the polymer is 100 to 220°C, and the kneading is carried out under pressure at 110 to 220°C. .