JP2019162002A - Insulating material, and coil for rotary electric machine - Google Patents

Abstract

To provide an insulating material with high thermal conductivity and a coil for rotary electric machine.SOLUTION: The insulating material has an isolation layer including a mica layer and an adhesive layer laminated by a single layer each. Defining the thickness and the thermal conductivity of the mica layer as tm (micrometer) and λm(W/mK); the thickness and the thermal conductivity of the adhesive layer as tr (micrometer) and λr(W/mK); and the thickness of the isolation layer as t all, λm is 0.2-0.7 W/mK. The insulating material satisfies the following formula (1), and the coil for rotary electric machine is insulated with the insulating material.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an insulating material and a coil for a rotating electrical machine.

  In general, the generator stator coil insulating material is formed around the high voltage conductor to prevent a ground fault to the grounding portion. However, in a system configured to cool the coil from the outside by ventilation, the insulating material covering the conductor hinders cooling of the coil. For this reason, thermal deterioration of the insulating material and increase in the conductive resistance of the conductor tend to occur.

  For the formation of the insulating material, a mica tape in which a glass cloth as a base material and a mica sheet made of mica powder are bonded together with an adhesive is used. A plurality of layers of mica tape are wound around the conductor and heated and cured, so that the mica sheet layer sandwiches the adhesive and the glass cloth.

  In this configuration, in order to solve the above-described problem, a technique for filling the adhesive layer with a high thermal conductive filler has been reported. This improves the overall thermal conductivity because the heat flow flows through the high thermal conductivity filler of the adhesive layer.

  Moreover, the structure which performs a chemical bond to the interface of a highly heat conductive filler and an adhesive agent is reported. As a result, the interfacial thermal resistance is lowered to further increase the thermal conductivity.

International Publication No. 2013/73496 JP 2014-171384 A Japanese Patent Laying-Open No. 2015-231322 International Publication No. 2015-53374 US Patent Application 2012/118612

  As in the enumerated technologies, the high thermal conductivity of the insulating material is improved, but the thermal resistance ratio of the mica layer increases with the improvement of the thermal conductivity of the adhesive layer. It has become difficult to efficiently improve the thermal conductivity.

  The present invention solves the above-mentioned problem. Regarding the thermal conductivity of the insulating material, when the contribution ratio of the mica layer is equal to or higher than the contribution ratio of the adhesive layer, the thermal conductivity of the mica layer is improved and heat is efficiently obtained. The purpose is to improve conductivity.

Therefore, the insulating material according to the embodiment of the present invention is an insulating material having an insulating layer in which a mica layer and an adhesive layer are laminated one by one,
The thickness and thermal conductivity of the mica layer are tm (μm) and λm (W / mK), the thickness and thermal conductivity of the adhesive layer are tr (μm) and λr (W / mK), and the insulating layer When the thickness of the film is tall (μm),
λm is 0.2 W / mK or more and 0.7 W / mK or less,
The following formula (1) is satisfied.

  And the coil for rotary electric machines by embodiment of this invention is insulated by said insulating material, It is characterized by the above-mentioned. In particular, the coil for the rotating electrical machine according to the embodiment of the present invention is preferably a coil that is insulated by an insulating material formed by winding the insulating material according to the embodiment of the present invention around the conductor around the conductor. Included as an example.

  According to the embodiment of the present invention, an insulating material having high thermal conductivity and high durability and a coil for a rotating electrical machine can be obtained.

Sectional drawing of the insulating material by embodiment of this invention. Insulation layer thermal resistance equivalent circuit. The graph which shows the dependence of the thermal conductivity of the insulating layer explaining Example 1 on a mica layer and an adhesive bond layer.

Hereinafter, examples of the insulating material according to the present invention will be described with reference to the drawings as necessary.
FIG. 1 is a schematic cross-sectional view of an insulating material 1 according to an embodiment of the present invention.
The insulating material 1 according to the embodiment of the present invention shown in FIG. 1 has an insulating layer in which a mica layer 2 and an adhesive layer 3 are laminated one by one. The mica layer 2 can be preferably formed by a large number of foil-like mica 21, for example. The adhesive layer 3 can be preferably formed of, for example, an adhesive 31 and a fibrous substrate (particularly preferably a glass cloth) 32. Insulating properties can be further improved by overlapping a plurality of insulating materials 1 shown in FIG.

Such an edge layer material 1 can be preferably manufactured as follows.
First, a mica sheet made of fired laminated mica and a glass cloth 32 are bonded together with an adhesive 31. The adhesive 31 can contain an inorganic filler as required. The adhesive was heated at 100 ° C. to 120 ° C. for a short time and kept in a semi-cured state. This state is called a prepreg sheet. Next, this prepreg sheet is cut into an appropriate width to form a tape, which is called a prepreg mica tape.

  The thickness (tm) of the mica layer 2 is preferably 1 to 100 μm, particularly preferably 10 to 40 μm. If the thickness of the mica layer is less than 1 μm, the insulation performance in the penetration direction of the mica layer is insufficient and easily breaks down. On the other hand, if it exceeds 100 μm, the insulation performance in the penetration direction of the mica layer is excessive. Therefore, an invalid thickness is not preferable because the size of the device is increased.

  Examples of the preferable adhesive 31 in the embodiment of the present invention include an adhesive composed of a main agent and a curing agent. As the main agent, for example, a glycidyl ether resin (bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, monomer type polyfunctional epoxy resin) is preferable. Examples of the curing agent include acid anhydride curing agents (tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic acid anhydride, hydrogenated methylnadic acid anhydride. , Trialkyltetrahydrophthalic anhydride, methylcyclohexene tetracarboxylic dianhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, ethylene glycol bisanhydro trimellitate, glycerin bis (Anhydrotrimellitate) monoacetate, dodecenyl succinic anhydride, aliphatic dibasic acid polyanhydride, chlorendic anhydride) are preferred.

  The thickness (tr) of the adhesive layer is preferably 1 to 100 μm, particularly preferably 10 to 40 μm. When the thickness of the adhesive layer is less than 1 μm, the insulation performance in the penetration direction of the mica layer is insufficient and easily breaks down. On the other hand, when the thickness exceeds 100 μm, the insulation performance of the mica layer in the penetration direction is low. Excessive and invalid thickness is undesirable because it increases the size of the device.

  A glass cloth 32 can be disposed on the adhesive layer 3. This glass cloth functions as a base material for holding the mica 21 described above, and has the strength and durability of the mica layer 2, the glass cloth 32, and the adhesive layer 3 combined by adhering and holding the adhesive 31. It makes it easier to provide improved insulation.

  The adhesive layer 3 is an inorganic compound, if necessary, preferably a filler-like inorganic material selected from the group consisting of alumina, aluminum nitride, aluminum hydroxide, boron nitride, magnesia, silicon nitride and silica. Compounds can be included. This can improve, for example, thermal conductivity, mechanical properties, and the like. The inorganic filler preferably has an average particle size of 0.001 to 100 μm, particularly 1 to 50 μm. And the abundance is preferably 10 to 90% by weight, particularly preferably 40 to 80% by weight, with respect to 100% by weight of the adhesive of the adhesive layer 3. When the amount of the inorganic filler is less than 10% by weight, the obtained property improvement effect is remarkably small. On the other hand, when it exceeds 90% by weight, the flexibility of the resin layer during the prepreg mica tape is impaired. Absent.

  The thermal conductivity (λr) of the adhesive layer 3 is preferably 0.20 to 30 W / mK, particularly preferably 1 to 5 W / mK. When the thermal conductivity (λr) is less than 0.20 W / mK, the thermal conductivity of the resin itself may be lower.

  The insulating material 1 shown in FIG. 1 is, for example, taping a prepreg mica tape to a conductor having a rectangular cross section of 13 mm × 92 mm 15 times with a half wrap, and hitting a plate for molding on the outside of the taped mica tape, After fixing with a heat-shrinkable tape, it can be obtained by vacuum degassing and heat-curing at a temperature of 150 ° C. or higher in a heating furnace.

  And the insulating layer produced in said process was cut out from the conductor side surface, and it processed into the cylinder shape of diameter 55mm and thickness about 3mm, and set it as the test body. At this time, the thickness direction coincides with the lamination direction of the tapes.

  About the produced test body, the heat conductivity was measured by the stationary method using the heat conductivity measuring apparatus (HC110) made from EKO Instruments Trading Co.Ltd. At this time, the temperature of the upper and lower plates was 95 ° C and 85 ° C. The obtained thermal conductivity was 0.67 W / mK.

  Moreover, after cutting the obtained test body in the lamination direction, the cross section was polished and the cut surface was observed. In cross-sectional observation, the thickness of the mica layer and the adhesive layer was measured and found to be 32 μm and 116 μm, respectively.

Here, the thermal resistance Rall of the insulating layer 1 can be expressed as Rall = Rr + Rm because the thermal resistance Rm of the mica layer 2 and the thermal resistance Rr of the adhesive layer 3 are connected in series (FIG. 2). . The thermal resistance R is equal to the inverse of the thermal conductivity multiplied by the thickness t and divided by the area considered. Therefore, the following formula (1 ″) can be obtained by arranging the relationship of thermal resistance with thickness and thermal conductivity. The formula (1 ″) can be expressed as the following formula (1 ′). be able to.

  Here, substituting the numerical value obtained experimentally into equation (1 ″) gives FIG. 3. According to this, in the thermal conductivity of a general epoxy resin such that λr is 0.25 W / mK. , Increase in λall by increasing λm is small.

  However, as described above, when λr is increased by the technology for improving λr listed as the prior art, the increase in λall by increasing λm increases. That is, it can be said that the optimum means for increasing λall is to increase λm above a certain λr.

  Here, the amount of increase in the thermal conductivity of the insulating layer when λr becomes λr + 0.1 is A, and the amount of increase in the thermal conductivity of the insulating layer when λm becomes λm + 0.1 is B, It can be defined as a condition where B> A. For example, when λr = 0.25 W / mK and λm = 0.2 W / mK, A = 0.06 and B = 0.02 are obtained, and it is effective to increase the thermal conductivity of the adhesive layer using the conventional technology. It is. However, when λr = 1.2 W / mK and λm = 0.2 W / mK, A = 0.02 and B = 0.14, respectively, and high thermal conductivity of the mica layer is effective.

  Although it is possible to improve λall by further improving λr using conventional technology, in the method of achieving high thermal conductivity by filling high thermal conductivity filler, the toughness of the material is increased by high filling of high thermal conductivity filler. The stability as a structure tends to be deteriorated.

Furthermore, even if the thermal conductivity of the same 0.1 W / mK is improved, for example, 0.2 W having a margin for improvement over the adhesive layer that achieved 1.2 W / mK by incorporating measures such as the prior art. The improvement of the thermal conductivity of the mica layer of / mK is advantageous when used as an insulating material because the form can be maintained and the stability is high.
Therefore, when the following formula (1) is satisfied, it is effective to increase the thermal conductivity of the mica layer.

  Any method can be employed as a method for improving the thermal conductivity of the mica layer. For example, preferably, a method of forming a mica layer with mica ore which has not been paper-made can be mentioned. According to this method, the thermal conductivity of 0.67 W / mK inherent to mica can be achieved.

  Further, by using peeled mica, it is possible to achieve both the original thermal conductivity of mica and the flexibility of the mica layer.

  In addition, when using laminated mica, although the flexibility is high, the mica is cleaved, so that thermal resistance is generated at the cleavage surface, and the thermal conductivity tends to decrease. Therefore, it is preferable to chemically modify the mica surface in order to reduce the interfacial thermal resistance between the mica and the adhesive.

  Examples of the chemical modification method include a coupling treatment. For example, a treatment using a silane coupling agent is preferable. More preferably, an aminosilane coupling agent or an epoxysilane coupling agent is preferably used in consideration of a reaction with an epoxy resin often used as an adhesive for electrical insulation.

  Preferable specific examples of such an aminosilane coupling agent include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3- Examples include aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, and N-phenyl-3-aminopropyltrimethoxysilane.

  As epoxy silane coupling agents, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyl Examples thereof include diethoxysilane and 3-glycidoxypropyltriethoxysilane.

  Based on the above, the thermal conductivity of the mica layer is 0.2 W / mK or higher for the mica sheet and 0.7 W / mK or lower for the mica ore.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, additions, and the like can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Insulating material, 2 ... Mica layer, 3 ... Adhesive layer, 21 ... Foil-like mica, 31 ... Adhesive, 32 ... Glass cloth

Claims (7)

An insulating material having an insulating layer in which a mica layer and an adhesive layer are laminated one by one,
The thickness and thermal conductivity of the mica layer are tm (μm) and λm (W / mK), the thickness and thermal conductivity of the adhesive layer are tr (μm) and λr (W / mK), and the insulating layer When the thickness of the film is tall (μm),
λm is 0.2 W / mK or more and 0.7 W / mK or less,
An insulating material characterized by satisfying the following formula (1).

  The insulating material according to claim 1, wherein a glass cloth is disposed on the adhesive layer.   The insulating material according to claim 1 or 2, wherein the adhesive layer comprises an inorganic compound selected from the group consisting of alumina, aluminum nitride, aluminum hydroxide, boron nitride, magnesia, silicon nitride, and silica.   The insulating material according to any one of claims 1 to 3, wherein the adhesive forming the adhesive layer is an organic adhesive having an epoxy group.   The insulating material according to any one of claims 1 to 3, wherein the adhesive forming the adhesive layer is an organic adhesive having a hydroxyl group.   The insulating material according to any one of claims 1 to 5, wherein the mica forming the mica layer is surface-treated with an organic compound.   A coil for rotating electrical machines, which is insulated by the insulating material according to any one of claims 1 to 6.

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