JP5115029B2 - High thermal conductive insulation and paper, coil bobbin and electric motor - Google Patents

Description

  The present invention relates to a high thermal conductivity insulating material for promoting heat dissipation from a heat source such as an electrical component, an electronic component, and an apparatus thereof and ensuring insulation, an insulating paper and a coil bobbin formed from the high thermal conductivity insulating material Further, the present invention relates to an electric motor having the insulating paper or coil bobbin.

  Recently, along with the progress of high density, miniaturization, and high output of electrical parts, electronic parts and devices composed of those parts, the amount of heat generated from these parts, coils incorporated in the equipment and semiconductors has also increased. One of the major issues is how to dissipate this heat.

  Conventionally, a heat conductive material in which a filler having thermal conductivity such as silicon carbide is dispersed in a polymer base material such as silicon rubber or EPDM is manufactured, and this is placed in contact with a heat source such as the above-mentioned parts or device. In addition, the heat dissipation from the heat source has been improved by interposing between the heat sink in which the above-described components are accommodated and the components.

  However, in the heat conductive material in which the filler is dispersed in the polymer matrix described above, it is difficult to fill the filler in the manufacturing process, and the moldability is deteriorated even when the filler is filled, and the mechanical strength of the molded product is reduced. It was a problem that was low. FIG. 3a shows a heat conductive insulating material in which a polymer a is filled with a large-diameter filler b.

  In addition, as disclosed in Patent Documents 1 to 3, there is a technique in which a thermal conductive material having an increased thermal conductivity can be obtained by dispersing two kinds of fillers having different particle sizes in the polymer base material. In this heat conductive material, the viscosity at the time of melting becomes large, and the moldability is remarkably lowered. This is schematically shown in FIG. 3b, and is a heat conductive insulating material in which a large-diameter filler b,... And a small-diameter filler c,.

  Further, as shown in FIG. 3c, fillers b,... Are dispersed in polymer base material a, and fillers b, b are connected by a low melting alloy d (for example, a tin alloy) to form a heat conduction path. There is also a technique for increasing the thermal conductivity, but in this case, the thermal conductive material itself conducts electricity, and therefore cannot be applied to insulation applications.

JP 2001-139733 A JP 2001-339019 A JP 2003-197833 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a highly heat-conductive insulating material having high heat dissipation performance and excellent moldability while ensuring insulation.

  In order to achieve the above object, the high thermal conductive insulating material according to the present invention has an aggregate in which a relatively small sized filler is aggregated around a relatively large sized filler dispersed in the polymer base material. It is characterized by being.

  Here, the filler has a spherical shape or other various shapes, and the shape is not limited. In addition, aggregates composed of relatively large fillers (coarse fillers) and relatively small fillers (fine fillers) include two types of filler aggregates of different sizes, Three or more different filler aggregates may be used. For example, it is a form in which a plurality of second-largest fillers agglomerate on the outer periphery side of the largest-size filler, and a minimum-size filler agglomerates on the outer periphery side of the maximum-size filler to form an aggregate. . In addition, when the relatively large filler is spherical or substantially spherical, the particle size can be generated to about 1 to 100 μm, and the particle size of the small size filler can be generated to about 0.1 to 10 μm. .

  One method of producing fillers with different dimensions is to produce a filler with a large size in advance, crush a part of this to produce a small size filler, and classify both. As another method, There is also a method in which a small-sized filler serving as a core is first generated, and a large-sized filler is generated while being chemically controlled.

  After producing relatively large and small sized fillers, the above-mentioned aggregates can be produced by mixing them together.

Here, the polymer base material can be selected from any one of silicon, nylon (registered trademark) , PP (polypropylene), PPS (polyphenylene sulfide), and LCP (liquid crystal polymer), and the filler is silicon carbide, silicon nitride, boron nitride. , Silica, aluminum oxide, aluminum nitride, magnesium oxide, or a mixture thereof. Since these materials are relatively inexpensive and easily available, they are suitable for the high thermal conductive insulating material of the present invention.

  According to the high thermal conductive insulating material of the present invention, the aggregate formed by agglomerating relatively small sized fillers around the relatively large sized fillers is dispersed in the polymer base material, so that Such an effect is obtained.

  The first effect is that the heat transfer efficiency between the polymer and the filler can be increased without increasing the filling amount of the filler or increasing the size of the filler. This is specified as a result of the analysis by the present inventors, and when compared with an insulating material in which a conventional uniform coarse filler is dispersed in a polymer, it is necessary to obtain an equal amount of heat transfer between fillers. The distance can be increased, which means that the filler loading can be reduced. Since the filler filling amount can be reduced, the moldability can be enhanced, and the multiple filling makes it easy for the aggregate to be unevenly distributed in the polymer, and the problem that this unevenly distributed portion becomes a weak part of the member strength can be solved at the same time. it can.

  The second effect is that the aggregate has a grain structure in which small-sized fillers protrude randomly from the outer periphery of large-sized fillers, so that the heat transfer direction has any one direction (anisotropic). There are many different directions (isotropic). In the insulating material having a conventional fibrous filler, it is difficult to obtain a desired thermal conductivity when the orientation direction and the heat transfer direction are different.

  The third effect is that the aggregate has the above-described structure, so that a small-sized filler can be embedded in the polymer to exert an anchor effect, and as a result, the interfacial strength between the polymer and the filler aggregate is increased. Thus, the mechanical strength of the insulating material can be increased.

  The high thermal conductive insulating material of the present invention described above has high formability in addition to high insulation and high heat dissipation. As its application, it is suitable for slot insulation paper and interphase insulation paper in a stator core of an electric motor, or a coil bobbin mounted on a stator tooth in a posture in which a coil is wound. It is particularly suitable for a drive motor for a hybrid vehicle and an electric vehicle that are demanding higher performance.

  As can be understood from the above description, according to the present invention, a heat conductive insulating material having high insulation and high heat dissipation, high mechanical strength and excellent moldability can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged schematic diagram of the internal structure of the high thermal conductive insulating material of the present invention. FIG. 2 is a simplified heat transfer model used in the analysis for calculating the minimum separation between fillers, and FIG. 3b and 3c are comparative example models, respectively.

  FIG. 1 is a diagram schematically showing the internal structure of a high thermal conductive insulating material. The high thermal conductive insulating material has a structure in which a large number of aggregates 4,... Are dispersed inside the polymer base material 1, and the aggregate 4 has a plurality of arbitrary shapes on the outer peripheral surface of the coarse filler 2 having an arbitrary shape. The fine fillers 3,...

  Here, the polymer base material 1 is formed of any one of silicon, nylon, PP (polypropylene), PPS (polyphenylene sulfide), and LCP (liquid crystal polymer), and the coarse filler 2 and the fine filler constituting the aggregate 4 3 is produced from any one of silicon carbide, silicon nitride, boron nitride, silica, aluminum oxide, aluminum nitride, magnesium oxide, or a mixture thereof.

  The coarse filler 2 and the fine filler 3 are first produced after the coarse filler 2 is produced, and a part of the coarse filler 2 is crushed and subdivided and classified to produce the fine filler 3 having a predetermined size. Aggregates 4 can be produced by mixing these coarse fillers 2 and fine fillers 3 together.

[Analysis and results for calculating minimum spacing between fillers]
The inventors of the present invention simply modeled the heat conductive insulating material of the present invention having the structure shown in FIG. 1, the conventional heat conductive insulating material shown in FIG. 3b, and the conventional heat conductive insulating material shown in FIG. 3c, respectively. (In order, Example, Comparative Example 1, Comparative Example 2), the minimum separation required to obtain an equal amount of heat transfer was determined by analysis. If the minimum separation is long, the amount of filling filler required is small, and the moldability can be improved. Moreover, it means that there is room to be able to be filled with more fillers when higher heat dissipation is required because the amount of fillers is small. The analysis was performed with a simple heat transfer model in a one-dimensional direction in a steady heat transfer state, and both coarse filler and fine filler were spherical. Furthermore, the heat source side is set to 150 ° C. and the heat dissipation side is set to 50 ° C.

  The analysis models of Examples and Comparative Examples 1 and 2 are shown in FIGS.

In the table, X is the spacing between fillers, L is the spacing between coarse fillers, Q (= ΔT / ΣR) is the amount of heat transfer, ΔT is the temperature difference between the heat source side and the heat dissipation side, and R is Heat transfer distance / (heat conductivity × heat transfer area). Furthermore, the thermal conductivity of the polymer is set to 0.3 (W / mK), the electrothermal area is set to 1 (μm ² ), and ΔT is set to 100 (K) (150-50 (K)).

  From Table 1, it was specified that the minimum spacing of the coarse filler to obtain an equal amount of heat transfer was the longest in the example (L = 60 μm), and therefore, the amount of filler could be reduced as compared with Comparative Examples 1 and 2. .

  Also, from this analysis result, since the minimum separation of the coarse filler in the example is the longest, the possibility of steric hindrance during filler filling is the lowest, and the possibility of molding failure due to viscosity hindrance is the lowest Was identified. In addition, it is obvious that an anchor effect by the fine filler embedded in the polymer can be expected, and a heat conductive insulating material having excellent mechanical strength as compared with the comparative example can be obtained.

  The above-described highly heat-conductive insulating material of the present invention can provide a heat-conductive insulating material that is excellent in insulation, heat dissipation and mechanical strength, and further excellent in moldability.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

It is the schematic diagram which expanded the internal structure of the high heat conductive insulating material of this invention. It is the simple heat transfer model used in the analysis which calculates the minimum separation between fillers, (a) is an example model, (b), (c) is a comparative example model, respectively. (A), (b), (c) is the schematic diagram which expanded the internal structure of the conventional heat conductive insulating material.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Polymer base material, 2 ... Coarse filler (relatively large filler), 3 ... Fine filler (relatively small filler), 4 ... Aggregate

Claims (6)

  A highly heat-conductive insulating material, characterized in that aggregates formed by agglomerating relatively small-sized fillers around relatively large-sized fillers are dispersed in a polymer base material. The polymer base material is made of any one of silicon, nylon (registered trademark) , PP (polypropylene), PPS (polyphenylene sulfide), and LCP (liquid crystal polymer), and the filler is silicon carbide, silicon nitride, boron nitride, silica. The high heat conductive insulating material according to claim 1, comprising any one of aluminum oxide, aluminum nitride, and magnesium oxide, or a mixture thereof.   Insulating paper formed by the high thermal conductive insulating material according to claim 1.   A coil bobbin formed of the high thermal conductive insulating material according to claim 1.   An electric motor to which the insulating paper according to claim 3 is applied as slot insulating paper or interphase insulating paper.   An electric motor in which a coil is wound around the coil bobbin according to claim 4 and mounted on a stator tooth.

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