WO2018003950A1 - Coil for rotary electric machine, method for producing coil for rotary electric machine, mica tape, method for producing mica tape, cured product of mica tape, and insulating article - Google Patents

Abstract

This coil for a rotary electric machine comprises a coil conductor and an insulating layer arranged on the outer periphery of the coil conductor. The insulating layer includes a mica tape. The mica tape includes: a mica layer including mica; and a backing layer including a backing material and an inorganic filler. The inorganic filler includes boron nitride having a first particle-size distribution peak that is present within a range of less than or equal to 5 µm and a second particle-size distribution peak that is present within a range of greater than or equal to 6 µm.

Description

Coil for rotating electrical machine, method for manufacturing coil for rotating electrical machine, mica tape, method for manufacturing mica tape, cured product and insulator of mica tape

The present invention relates to a coil for a rotating electrical machine, a method for manufacturing a coil for a rotating electrical machine, a mica tape, a method for manufacturing a mica tape, a cured product of an mica tape, and an insulator.

A coil (hereinafter also simply referred to as a coil) used in a rotating electrical machine such as a generator or an electric motor generally has a coil conductor and an insulating layer disposed on the outer periphery of the coil conductor to insulate the coil conductor from the external environment. is doing. As a material for forming an insulating layer for insulating a member (insulator) such as a coil from an external environment, an insulating material using mica called a mica tape is known. The mica tape is generally mainly composed of a backing layer containing a backing material and a mica layer containing mica, and an insulating layer is formed by curing a resin impregnated in the mica tape.

On the other hand, in the field of generators and the like that employ an indirect cooling method in which hydrogen gas or air is cooled outside the coil, it is desired to increase the thermal conductivity of the insulating layer provided on the outside of the coil. As a technique for increasing the thermal conductivity of the insulating layer, a technique in which an inorganic filler having a high thermal conductivity is contained in the mica tape can be mentioned.

For example, Patent Document 1 discloses a mica tape in which alumina having a high thermal conductivity is filled as an inorganic filler in a mica layer. By using this mica tape, 0.32 W / (m · K) is disclosed. An insulating layer having a thermal conductivity of ˜0.36 W / (m · K) is obtained.

Patent Document 2 discloses a mica tape in which a thermal conductive layer containing an inorganic filler having a high thermal conductivity is disposed on one surface, and 0.35 W / (m · K) to 0.48 W / ( An insulating layer having a thermal conductivity of m · K) is obtained.

Patent Document 3 discloses a method in which HTC (high thermal conductivity) particles are infiltrated into a backing layer of a mica tape, and the composite tape is impregnated into the composite tape through the backing layer.

Japanese Patent Laid-Open No. 2005-199562 JP 2002-93257 A Special table 2009-532242

Although it is effective to contain an inorganic filler as a method for improving the thermal conductivity of mica tape, from the viewpoint of production cost, etc., it is a technique for suppressing the amount of inorganic filler to be used while achieving good thermal conductivity. Development is awaited.
However, the mica tape containing the inorganic filler may drop off from the mica tape. In particular, when a mica tape is wound around a coil conductor and immersed in a resin varnish for impregnation, the inorganic filler may flow out of the mica tape into the resin varnish and the amount of the inorganic filler remaining in the insulating layer may be reduced. Therefore, in order to obtain a high thermal conductivity, a large amount of the inorganic filler may be blended.
There is also a problem that the quality of the resin varnish changes due to the outflow of the inorganic filler from the mica tape into the resin varnish.

In view of the above circumstances, an object of the present invention is to provide a coil for rotating electricity having an insulating layer containing a mica tape that can suppress the dropping of the inorganic filler from the mica tape, and a method for manufacturing the same. It is an object of the present invention to provide a mica tape capable of suppressing the falling off of the inorganic filler from the mica tape, a method for producing the mica tape, a cured product of the mica tape, and an insulator using the mica tape.

Specific means for achieving the above object are as follows.
<1> a coil conductor and an insulating layer disposed on an outer periphery of the coil conductor, wherein the insulating layer includes a mica tape, and the mica tape includes a mica layer including mica, a backing material, and an inorganic filler. And the inorganic filler comprises boron nitride having a first particle size distribution peak existing in a range of 5 μm or less and a second particle size distribution peak existing in a range of 6 μm or more. Including coils for rotating electrical machines.
<2> In the mica tape, the first particle size distribution peak of the boron nitride exists in a range of 2 μm to 5 μm, and the second particle size distribution peak exists in a range of 6 μm to 10 μm. Coil for rotating electrical machines.
<3> The content of the inorganic filler in the mica tape is 20% by volume to 50% by volume of the total volume of non-volatile components excluding the mica and the backing material, according to <1> or <2> Coil for rotating electrical machines.
<4> The step of winding the mica tape around the outer periphery of the coil conductor, and the step of forming the insulating layer including the mica tape wound around the outer periphery of the coil conductor. The manufacturing method of the coil for rotary electric machines of any one of 3>.
<5> A mica layer containing mica and a backing layer containing a backing material and an inorganic filler, wherein the inorganic filler has a first particle size distribution peak existing in a range of 5 μm or less and a range of 6 μm or more. A mica tape comprising boron nitride having a second particle size distribution peak present.
<6> The mica tape according to <5>, wherein the first particle size distribution peak of the boron nitride exists in a range of 2 μm to 5 μm, and the second particle size distribution peak exists in a range of 6 μm to 10 μm.
<7> The mica tape according to <5> or <6>, wherein the content of the inorganic filler is 20% by volume to 50% by volume of the total volume of nonvolatile components excluding the mica and the backing material.
<8> A step of arranging a backing material on mica to prepare a laminate, a first particle size distribution peak existing in a range of 5 μm or less, and a second particle size distribution peak existing in a range of 6 μm or more And a step of applying a composition containing an inorganic filler containing boron nitride and a resin component to the backing material side of the laminate.
<9> The method for producing a mica tape according to claim 8, wherein the content of the inorganic filler in the composition is 20% by volume to 50% by volume of the entire nonvolatile content of the composition.
<10> The method for producing a mica tape according to <8> or <9>, wherein the viscosity at the time of application of the composition is 500 mPa · s to 3000 mPa · s.
<11> The cured product of mica tape according to any one of <5> to <7>, comprising a resin component and obtained by curing the resin component.
<12> An insulator having an insulator and an insulating layer that is a cured product of the mica tape according to <11>, which is disposed on at least a part of the surface of the insulator.

According to the present invention, there are provided a coil for rotating electricity having an insulating layer containing a mica tape that can prevent the inorganic filler from dropping off from the mica tape, and a method for manufacturing the same. Moreover, according to this invention, the mica tape which can suppress the drop-off | omission of the inorganic filler from a mica tape, the manufacturing method of a mica tape, the hardened | cured material of a mica tape, and an insulator using the same are provided.

It is a schematic sectional drawing showing an example of a structure of a mica tape. Boron nitride state (A) when both boron nitride corresponding to the first particle size distribution peak and boron nitride corresponding to the second particle size distribution peak exist, and boron nitride corresponding to the second particle size distribution peak It is a conceptual diagram showing the state (B) of boron nitride in the case where only is present. It is a graph showing the particle size distribution of the boron nitride used in the Example.

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the components (including element steps and the like) are not essential unless otherwise specified. The same applies to numerical values and ranges thereof, and the present invention is not limited thereto.

In this specification, the term “process” includes a process that is independent of other processes and includes the process if the purpose of the process is achieved even if it cannot be clearly distinguished from the other processes. It is.
In the present specification, numerical values indicated by using “to” include numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range. Good. Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.
In the present specification, the content rate or content of each component in the composition is such that when there are a plurality of substances corresponding to each component in the composition, the plurality of kinds present in the composition unless otherwise specified. It means the total content or content of substances.
In the present specification, the particle diameter of each component in the composition is a mixture of the plurality of types of particles present in the composition unless there is a specific indication when there are a plurality of types of particles corresponding to each component in the composition. Means the value of.
In this specification, the term “layer” refers to the case where the layer is formed only in a part of the region in addition to the case where the layer is formed over the entire region. Is also included.
In this specification, the term “lamination” indicates that layers are stacked, and two or more layers may be combined, or two or more layers may be detachable.

<Coils for rotating electrical machines>
The coil for a rotating electrical machine of the present embodiment has a coil conductor and an insulating layer disposed on the outer periphery of the coil conductor, and the insulating layer includes mica tape,
The mica tape has a mica layer containing mica, and a backing layer containing a backing material and an inorganic filler, and the inorganic filler has a first particle size distribution peak existing in a range of 5 μm or less, and 6 μm or more. Boron nitride having a second particle size distribution peak present in the range.

The coil for a rotating electrical machine of the present embodiment includes a first particle size distribution peak in which the mica tape forming the insulating layer exists as an inorganic filler in a range of 5 μm or less, and a second particle size distribution peak in a range of 6 μm or more. The inclusion of boron nitride having, prevents the inorganic filler from falling off. The reason for this is not clear, but boron nitride has large boron nitride particles by having a first particle size distribution peak in the range of 5 μm or less and a second particle size distribution peak in the range of 6 μm or more. When small boron nitride particles enter between the layers, the dispersibility of boron nitride in the composition (varnish) used for producing the mica tape is improved and the viscosity is lowered. It can be suppressed. Furthermore, it is considered that in the backing layer formed using a composition in which boron nitride is well dispersed, boron nitride is easily trapped by the backing material, and the inorganic filler does not easily fall off.

Details and preferred aspects of the mica tape used for forming the insulating layer of the coil of the present embodiment are the same as those of the mica tape of the present embodiment described later. Further, the material, shape, size, and the like of the coil conductor used in the coil of the present embodiment are not particularly limited, and can be selected according to the use of the coil.

<Manufacturing method of coil for rotating electrical machine>
The method for manufacturing a coil for a rotating electrical machine of the present embodiment includes a step of winding a mica tape around the outer periphery of a coil conductor, a step of forming the insulating layer including the mica tape wound around the outer periphery of the coil conductor, Have

The method of winding the mica tape around the outer periphery of the coil conductor is not particularly limited, and a usual method can be adopted.

The method for forming the insulating layer including the mica tape wound around the outer periphery of the coil conductor is not particularly limited. For example, after a mica tape is wound around a coil conductor, the mica tape is heated while being pressed (heat press), and the resin component contained in the mica tape is caused to flow out of the mica tape in advance to fill the space between the overlapping mica tapes. The resin component is then formed by a method of curing this to form an insulating layer (in the case of prepreg mica tape), and after winding the mica tape around the coil conductor, a vacuum pressure impregnation method (Vacuum Pressure Impression, VPI). Examples include a method of impregnating mica tape and curing it to form an insulating layer (in the case of dry mica tape).

<Mica tape>
The mica tape of the present embodiment has a mica layer containing mica, a backing layer containing a backing material and an inorganic filler, and the inorganic filler has a first particle size distribution peak existing in a range of 5 μm or less, And boron nitride having a second particle size distribution peak existing in a range of 6 μm or more. Boron nitride may have a particle size distribution peak other than the first particle size distribution peak and the second particle size distribution peak. Further, two or more first particle size distribution peaks may be present, and two or more second particle size distribution peaks may be present.

As a result of studies by the present inventors, it has been found that the mica tape of the present embodiment can form an insulating layer excellent in thermal conductivity while suppressing the amount of inorganic filler.
Although the reason is not clear, the present inventors consider as follows. First, it is mentioned that boron nitride contained as an inorganic filler exhibits high thermal conductivity. Furthermore, the boron nitride has a first particle size distribution peak that exists in a range of 5 μm or less and a second particle size distribution peak that exists in a range of 6 μm or more, so that small boron nitride is present between large boron nitride particles. It is considered that the dispersion of boron nitride in the composition (varnish) used for the preparation of the mica tape is improved and the viscosity is lowered, so that uneven distribution of boron nitride after coating is suppressed. It is done. Further, it is considered that boron nitride is easily trapped by the backing material in a backing layer formed using a composition in which boron nitride is well dispersed, and boron nitride is not easily dropped off.

FIG. 2 shows the state of boron nitride when both boron nitride corresponding to the first particle size distribution peak and boron nitride corresponding to the second particle size distribution peak exist, and nitridation corresponding to the second particle size distribution peak. It is a conceptual diagram showing the state of boron nitride when only boron exists.
As shown in FIG. 2A, when both boron nitride particles 7 corresponding to the first particle size distribution peak and boron nitride particles 8 corresponding to the second particle size distribution peak are present, the boron nitride is a surface. Orientation in a certain direction is suppressed, and the anisotropy of thermal conductivity tends to be reduced.
On the other hand, as shown in FIG. 2B, when only boron nitride particles 8 corresponding to the second particle size distribution peak are present, the thermal conductivity tends to be higher than that of boron nitride of the same filling amount. The boron nitride is oriented in a certain direction in the plane, and the difference in thermal conductivity between the in-plane direction and the thickness direction tends to be large and anisotropy tends to occur.
Although not shown, when only boron nitride particles 7 corresponding to the first particle size distribution peak are present, the thermal conductivity anisotropy is suppressed, but the thermal conductivity is compared with boron nitride of the same filling amount. The rate tends to be low.

From the viewpoint of improving the particle dispersibility of boron nitride, it is preferable that the first particle size distribution peak of boron nitride exists in the range of 1 μm to 4 μm and the second particle size distribution peak exists in the range of 8 μm to 11 μm. More preferably, the first particle size distribution peak is in the range of 2 μm to 3 μm, and the second particle size distribution peak is in the range of 9 μm to 10 μm.

In the present specification, when the particle size distribution peak is present in a certain range, the case where all of the peaks including the particle size distribution peak exist within the range, and the case where a part of the mountain exists outside the range. Both are included. Furthermore, in the volume-based particle size distribution curve, the first particle size distribution peak existing in the range of 5 μm or less is smaller than the second particle size distribution peak existing in the range of 6 μm or more (peak height is low). Is preferred. The second particle size distribution peak is preferably in the range of 6 μm to 100 μm.

Boron nitride preferably has a frequency at the first particle size distribution peak of 0.1% to 5%, more preferably 1% to 4%. The frequency at the second particle size distribution peak is preferably 1% to 6%, and more preferably 2% to 5%.
Boron nitride preferably has a frequency at the first particle size distribution peak / frequency value at the second particle size distribution peak of less than 1, preferably 0.9 or less, and 0.8 or less. More preferred. Further, the frequency value at the first particle size distribution peak / the frequency value at the second particle size distribution peak is preferably 0.1 or more, and more preferably 0.2 or more.

Boron nitride preferably has a particle diameter (D10) of 0.1 μm to 3 μm when the accumulation from the small diameter side of the volume-based particle size distribution curve is 10%, and preferably has a particle diameter (D50) of 50%. ) Is preferably 3 μm to 8 μm, and the particle diameter (D90) at 90% is preferably 8 μm to 100 μm. The value of D10 / D90 is preferably 0.001 to 0.333, and the value of D90-D10 is preferably 6 μm to 99 μm.

The particle size distribution peak of boron nitride can be measured by a laser diffraction method. When the laser diffraction method is used, boron nitride is introduced into pure water and dispersed with an ultrasonic disperser, and a laser diffraction / scattering particle size distribution measuring device (for example, Nikkiso Co., Ltd., “Microtrack MT3000II” is obtained from the obtained dispersion. )). When measuring the particle size distribution peak by extracting the filler from the mica tape, the filler component is extracted from the backing layer using an organic solvent and sufficiently dispersed with an ultrasonic disperser or the like. By measuring the particle size distribution of this dispersion, the particle size distribution of the filler can be measured.

FIG. 1 is a schematic cross-sectional view showing an example of the structure of the mica tape of this embodiment. As shown in FIG. 1, the mica tape may have a mica layer 6 containing mica 4 and a backing layer 5 containing a backing material 2 and an inorganic filler 1. Further, the mica layer 6 and the backing layer 5 may each contain the resin component 3. The resin component 3 may be included in both the mica layer 6 and the backing layer 5 or only in one. When the mica layer 6 (or the backing layer 5) includes the resin component 3, the resin component 3 may be included in the entire mica layer 6 (or the backing layer 5) or may be partially included.

The mica tape of this embodiment is a mica tape (prepreg mica tape) used in a method for forming an insulating layer by curing a resin component contained in a mica tape in advance after the mica tape is wound around an object to be insulated. Alternatively, it may be a mica tape (dry mica tape) used in a method of forming an insulating layer by curing a resin component impregnated after being wound around an insulator.

(Mica)
The kind of mica is not particularly limited. Examples include unfired hard mica, fired hard mica, unfired soft mica, fired soft mica, synthetic mica, and flake mica. Among these, unfired hard mica is preferable from the viewpoint of adhesion between mica and the resin component.

The particle size of mica is not particularly limited. For example, from the viewpoint of insulation, when sieving using a JIS standard sieve, the proportion of mica pieces having a particle diameter of 2.8 mm or more is preferably less than 45% by mass of the whole mica pieces, It is more preferably 30% by mass or less, and further preferably 20% by mass or less, based on the entire mica piece.

From the viewpoint of securing sufficient dielectric breakdown electric field strength, the proportion of mica pieces having a particle diameter of 0.5 mm or more when sieved using a JIS standard sieve is 40% by mass or more of the entire mica pieces. Is preferable, and it is more preferable that it is 60 mass% or more.

The JIS standard sieve conforms to JIS-Z-8801-1: 2006 and corresponds to ISO3310-1: 2000. In addition, when using ISO3310-1: 2000, it is preferable to apply the one having a square mesh shape as in JIS-Z-8801-1: 2006.

Mica may be used alone or in combination of two or more. When two or more mica are used in combination, for example, when two or more mica having the same component and different particle sizes are used, when two or more mica having the same particle size and different components are used, and the average particle size and component The case where 2 or more types of mica having different types is used is mentioned.

The amount of mica in the mica layer is not particularly limited. For example, a range of 80 g / m ² to 230 g / m ² is preferable, and a range of 100 g / m ² to 200 g / m ² is more preferable. If the amount of mica in the mica layer is 80 g / m ² or more, a decrease in insulation tends to be suppressed. If the amount of mica in the mica layer is 230 g / m ² or less, the thickness of the mica tape can be reduced, and the decrease in thermal conductivity tends to be suppressed.

(Lining material)
The type of the backing material is not particularly limited. For example, a glass cloth is mentioned. By using glass cloth as the backing material, the inorganic filler is taken in between the fibers constituting the glass cloth, and the falling of the inorganic filler tends to be suppressed. Further, the resin component penetrated between the fibers tends to be well integrated with the adjacent mica layer, and the thermal conductivity tends to be improved. Furthermore, there is a tendency that cuts, cracks and the like are less likely to occur when wound around an insulator.

When a glass cloth is used as the backing material, a part of the fiber may be an organic material. The fiber comprised in particular with an organic material is not restrict | limited, Fibers, such as an aramid, polyamide, a polyimide, polyester, are mentioned. When a part of the glass cloth is a fiber composed of an organic material, the warp, the weft, or both may be a fiber composed of an organic material.

The average thickness of the backing material is not particularly limited. For example, the thickness is preferably 30 μm to 60 μm, and more preferably 45 μm to 50 μm. When the average thickness of the backing material is 30 μm or more, it is suppressed that the backing layer becomes too thin following the thickness of the backing material when the mica tape is pressed, and a decrease in thermal conductivity is suppressed. There is a tendency. If the thickness of the backing material is 60 μm or less, the thickness of the mica tape can be suppressed, and the occurrence of breakage, cracks, and the like of the mica tape during the process of winding the mica tape around the insulator tends to be suppressed.

In this embodiment, the average thickness of the backing material is the arithmetic average value of the measured values obtained by measuring the thickness of the backing material at a total of 10 locations using a micrometer (MDC-SB, Mitutoyo Corporation). .

The backing material may be surface-treated if necessary. Examples of the surface treatment method for the backing material include treatment with a silane coupling agent.

(Inorganic filler)
The inorganic filler includes boron nitride having a first particle size distribution peak that exists in a range of 5 μm or less and a second particle size distribution peak that exists in a range of 6 μm or more. Since boron nitride exhibits higher thermal conductivity than other inorganic fillers (for example, alumina), the thermal conductivity of the insulating layer formed from the mica tape tends to be further improved. The inorganic filler may include inorganic fillers other than boron nitride such as silica and alumina. When the inorganic filler contains boron nitride and an inorganic filler other than boron nitride, the proportion of boron nitride in the inorganic filler is preferably 50% by mass or more, more preferably 70% by mass or more, and 90% by mass. More preferably, it is the above.

The type of boron nitride is not particularly limited, and examples include hexagonal boron nitride (h-BN), cubic boron nitride (c-BN), and wurtzite boron nitride. Among these, hexagonal boron nitride (h-BN) is preferable. The boron nitride may be primary particles of boron nitride formed in a scale shape or secondary particles formed by agglomeration of primary particles.

The average particle size of the inorganic filler is not particularly limited as long as it contains boron nitride having a first particle size distribution peak existing in the range of 5 μm or less and a second particle size distribution peak existing in the range of 6 μm or more. . For example, it is preferably in the range of 3 μm to 8 μm, and more preferably in the range of 5 μm to 7 μm.

The average particle size of the inorganic filler can be measured by using, for example, a laser diffraction / scattering particle size distribution measuring apparatus (Nikkiso Co., Ltd., “Microtrack MT3000II”). Specifically, an inorganic filler is introduced into pure water and then dispersed with an ultrasonic disperser. By measuring the particle size distribution of the dispersion, the particle size distribution of the inorganic filler is measured. Based on this particle size distribution, the particle size (D50) corresponding to 50% volume accumulation from the small diameter side is determined as the average particle size.

The inorganic filler preferably has an aspect ratio in the range of 1 to 10, and more preferably in the range of 1 to 9. Further, the boron nitride contained in the inorganic filler preferably has an aspect ratio in the range of 1 to 10, more preferably in the range of 1 to 9. When the aspect ratio of the inorganic filler or boron nitride is in the range of 1 to 10, the surface area where the inorganic filler or boron nitride is in contact with the resin increases, and the inorganic filler or boron nitride is more closely attached to the backing material through the resin, and the coil There is a tendency that the scattering of the inorganic filler is more suppressed when the mica tape is wound around.

For the aspect ratio of the inorganic filler or boron nitride, the ratio of the length of the major axis to the minor axis (major axis / minor axis) is measured for each of 20 representative particles, and the arithmetic average value of the obtained measured values is used.

The method for measuring the aspect ratio of the inorganic filler or boron nitride is not particularly limited. For example, a cured product of mica tape is cut in the thickness direction, and the cut surface is smoothed by ion milling, and then the cut surface obtained by depositing platinum is scanned with an electron microscope (SEM) (magnification: 3000 times). And can be measured using a micrometer.

The inorganic filler may be used alone or in combination of two or more. As a case where two or more inorganic fillers are used in combination, for example, when two or more inorganic fillers having the same component and different average particle sizes are used, two or more inorganic fillers having the same average particle size and different components are used, and A case where two or more inorganic fillers having different average particle diameters and types are used.

If necessary, the inorganic filler may be surface-treated by a coupling agent, heat treatment or light treatment.
For example, in the case of heat treatment, impurities on the surface of the inorganic filler are removed by heating the inorganic filler at an appropriate high temperature (for example, 250 ° C. to 800 ° C.) for 1 hour to 3 hours. Therefore, the affinity when the inorganic filler is mixed with the resin component is improved, and the viscosity of the composition containing the inorganic filler and the resin component is lowered and tends to be easily applied. Further, the coated surface of the composition has few smears and irregularities and tends to improve smoothness.

(Resin component)
The mica tape may contain a resin component. The kind of resin used as the resin component is not particularly limited. From the viewpoint of curing the mica tape to form the insulating layer, a curable resin is preferable, and a thermosetting resin is more preferable. Examples of the curable resin include an epoxy resin, a phenol resin, an unsaturated polyester resin, and a silicone resin. From the viewpoint of adhesion between the mica layer and the backing layer and electrical insulation, an epoxy resin is preferable.

Epoxy resins in the case of using an epoxy resin as a resin component include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolak type epoxy resin, naphthalene type epoxy resin, cycloaliphatic epoxy resin, etc. Is mentioned. Among these, from the viewpoint of heat resistance, phenol novolac type epoxy resins, bisphenol A type epoxy resins and bisphenol F type epoxy resins are preferable.

The epoxy equivalent of the epoxy resin is not particularly limited. For example, it is preferably 130 g / eq to 500 g / eq, more preferably 135 g / eq to 400 g / eq, and even more preferably 140 g / eq to 300 g / eq. The epoxy equivalent is measured by dissolving a precisely weighed epoxy resin in a solvent such as methyl ethyl ketone, adding acetic acid and a tetraethylammonium bromide acetic acid solution, and then performing potentiometric titration with a perchloric acid acetic acid standard solution. An indicator may be used for potentiometric titration.

The number average molecular weight of the resin used as the resin component is not particularly limited. For example, from the viewpoint of fluidity, it is preferably 100 to 100,000, more preferably 200 to 50,000, and still more preferably 300 to 10,000. The number average molecular weight of the resin is a value measured under the following conditions using a gel permeation chromatography method (GPC) according to a conventional method.

〔Measurement condition〕
Pump: L-6000 (Hitachi, Ltd.)
Column: TSKgel (registered trademark) G4000HHR + G3000HHR + G2000HXL (Tosoh Corporation)
Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran (without chromatography stabilizer, Wako Pure Chemical Industries, Ltd.)
Sample concentration: 5 g / L (tetrahydrofuran soluble component)
Injection volume: 100 μL
Flow rate: 1.0 mL / min Detector: Differential refractometer (RI-8020, Tosoh Corporation)
Molecular weight calibration reference material: Standard polystyrene Data processor: GPC-8020 (Tosoh Corporation)

When the mica tape contains a curable resin as a resin component, a curing agent may be included as a resin component. The curing agent is not particularly limited and can be appropriately selected depending on the type of the curable resin. A hardening | curing agent may be used individually by 1 type, or may use 2 or more types together.
When the curable resin is an epoxy resin, the curing agent can be appropriately selected from curing agents usually used as a curing agent for epoxy resins. Specific examples include amine curing agents such as dicyandiamide and aromatic diamine; phenol resin curing agents such as phenol novolac and cresol novolac; acid anhydride curing agents such as alicyclic acid anhydrides and the like. When the curable resin is an epoxy resin, the ratio of the curing agent to the epoxy resin should be 0.8 to 1.2 in terms of equivalent ratio (curing agent / epoxy resin) from the viewpoint of curability and electrical characteristics of the cured product To preferred.

(Curing catalyst)
When the mica tape includes a curable resin as a resin component, a curing catalyst may be included for the purpose of accelerating the curing reaction of the curable resin. The curing catalyst is not particularly limited, and can be selected according to the type of the curable resin and the curing agent used as necessary. Specific examples of the curing catalyst include tertiary amine compounds such as trimethylamine, imidazole compounds such as 2-methylimidazole and 2-methyl-4-ethylimidazole, organometallic salts such as tin, zinc and cobalt, boron trifluoride. Examples include amine complexes of Lewis acids such as monoethylamine, and organic phosphorus compounds such as organic phosphine compounds. A hardening accelerator may be used individually by 1 type, or may use 2 or more types together.
When the mica tape contains a curing catalyst, the content is not particularly limited. For example, when an epoxy resin is used as the resin component, the content of the curing catalyst is generally in the range of 0.01% by mass to 5% by mass with respect to the total amount of the epoxy resin and the curing agent included as necessary. is there.

(Other ingredients)
The mica tape may contain other components other than the components described above as necessary. Examples of other components include coupling agents, antioxidants, anti-aging agents, stabilizers, flame retardants, and thickeners. When a mica tape contains these components, the content is not particularly limited.

<Overall configuration of mica tape>
The mica tape of this embodiment has a mica layer containing mica and a backing layer containing a backing material and boron nitride, and may have other layers as necessary. Examples of the other layer include a protective layer (protective film) provided on the outermost surface of the mica tape.

The average thickness of the mica tape (the total thickness of the mica layer and the backing layer) is not particularly limited. For example, the average thickness of the mica tape may be 400 μm or less, preferably 350 μm or less, and more preferably 300 μm or less.

When the mica tape is used as a prepreg mica tape, the average thickness of the mica tape is preferably 300 μm or less and more preferably 290 μm or less from the viewpoint of easy winding of the mica tape. From the viewpoint of electrical insulation, the average thickness of the mica tape is preferably 120 μm or more, more preferably 150 μm or more, and further preferably 160 μm or more.

When the mica tape is used as a dry mica tape, the average thickness of the mica tape is preferably 220 μm or less and more preferably 190 μm or less from the viewpoint of ease of winding the mica tape. From the viewpoint of electrical insulation, the average thickness of the mica tape is preferably 120 μm or more, more preferably 150 μm or more, and further preferably 180 μm or more.

The average thickness of the mica layer is not particularly limited. From the viewpoint of ease of winding the mica tape, the average thickness of the mica layer is preferably 180 μm or less, and more preferably 170 μm or less. From the viewpoint of electrical insulation, the average thickness of the mica layer is preferably 80 μm or more, and more preferably 90 μm or more.

The average thickness of the backing layer is not particularly limited. From the viewpoint of ease of winding the mica tape, the average thickness of the backing layer is preferably 60 μm or less, and more preferably 50 μm or less. From the viewpoint of the strength of the mica tape, the average thickness of the backing layer is preferably 10 μm or more, and more preferably 20 μm or more.

In this embodiment, the average thickness of the mica tape (the total thickness of the mica layer and the backing layer) was measured at a total of 10 locations using a micrometer (MDC-SB, Mitutoyo Corporation). The arithmetic average value of the measured values obtained is used.

In the present embodiment, the thickness of the mica layer and the backing layer in the mica tape is determined by measuring the thickness of the mica layer and the backing layer in the cross section of the mica tape with a micrometer of a stereomicroscope (for example, Olympus Corporation “BX51”). Observe 3 points and use the arithmetic average.

The content of the inorganic filler in the nonvolatile content excluding mica and the backing material of the mica tape is not particularly limited. For example, it is preferably 20% by volume to 50% by volume and more preferably 25% by volume to 35% by volume of the total volume of non-volatile components excluding mica and the backing material. When the content of the inorganic filler is 20% by volume or more of the total volume of nonvolatile components excluding mica and the backing material, the thermal conductivity of the insulating layer formed from the mica tape tends to be further improved. When the content of the inorganic filler is 50% by volume or less of the total volume of non-volatile components excluding mica and the backing material, filling of the inorganic filler into the resin component tends to be facilitated.

The content of non-volatile components excluding mica and the backing material in the total mass of the mica layer and the backing layer of the mica tape is not particularly limited. For example, it is preferably 5% by mass to 45% by mass of the total mass of the mica layer and the backing layer, more preferably 10% by mass to 30% by mass, and further preferably 15% by mass to 20% by mass. preferable. When the content of nonvolatile components excluding mica and the backing material is 5% by mass or more of the total mass of the mica layer and the backing layer, the thermal conductivity tends to be more effectively improved. When the non-volatile content excluding mica and the backing material is 45% by mass or less of the total mass of the mica layer and the backing layer, an increase in the thickness of the mica tape tends to be suppressed. In addition, varnish impregnation tends to proceed during the production of mica tape.

The content of the resin component in the nonvolatile content excluding mica and the backing material of the mica tape is not particularly limited. For example, it is preferably 35% by mass to 70% by mass, more preferably 50% by mass to 65% by mass, and more preferably 55% by mass to 60% by mass with respect to the total mass of the nonvolatile content excluding mica and the backing material. More preferably. When the content of the resin component is 35% by mass or more of the total mass of nonvolatile components excluding mica and the backing material, the adhesion between the backing layer and the mica layer tends to be improved. When the content of the resin component is 70% by mass or less of the total nonvolatile content excluding mica and the backing material, the thermal conductivity tends to be improved.

The content of the resin component in the mica tape is not particularly limited and can be selected according to the use of the mica tape. For example, the content of the resin component may be 40% by mass or less of the total mass of the mica layer and the backing layer, and is preferably 5% by mass to 33% by mass.

When the mica tape is used as a prepreg mica tape, the content of the resin component is preferably 25% by mass to 33% by mass of the total mass of the mica layer and the backing layer, for example, 25% by mass to 30% by mass. It is more preferable that When the content of the resin component is 25% by mass or more of the total mass of the mica layer and the backing layer, the mica from the mica tape and, if necessary, the falling off (powder off) of the inorganic filler are suppressed, and the insulator As a result of the occurrence of cracks, cuts, wrinkles, and the like of the mica tape when the mica tape is wound around, the insulation reliability and the thermal conductivity tend to be suppressed. On the other hand, when the content of the resin component is 33% by mass or less of the total mass of the mica layer and the backing layer, an increase in the thickness of the mica tape is suppressed and good winding properties tend to be maintained. Furthermore, the resin component tends to be prevented from dropping beyond the volume necessary to fill the gap between the overlapping mica tapes with the mica tape wound around the insulator. As a result, generation of voids is reduced, and a decrease in insulation reliability tends to be suppressed.

When the mica tape is used as a dry mica tape, the content of the resin component in the mica tape is preferably 5% by mass to 15% by mass of the total mass of the mica layer and the backing layer, for example, 5% by mass. More preferably, it is ˜12% by mass, and further preferably 8% by mass to 10% by mass. When the content of the resin component is 5% by mass or more of the total mass of the mica layer and the backing layer, the adhesion between the backing layer and the mica layer tends to be sufficiently secured. On the other hand, when the content of the resin component is 15% by mass or less of the total mass of the mica layer and the backing layer, high thermal conductivity tends to be achieved.

In this embodiment, the content rate of the resin component in the mica tape is calculated by the following method, for example.
The mica tape cut to a size of 30 mm in width and 50 mm in length is heated in an electric furnace at 600 ° C. for 2 hours, and the mass reduction rate (%) before and after heating is obtained by the following formula. The above process is performed three times, and an arithmetic average value of the obtained values is obtained.
Content of resin component = {(mass before heating−mass after heating) / mass before heating} × 100

When the mica tape is used as a dry mica tape, the content of the resin component in the mica layer is preferably 15% by mass or less of the total mass of the mica layer, and more preferably 10% by mass or less. More preferably, it is 5 mass% or less, and it is especially preferable that it is 0 mass%.

The mica layer preferably contains substantially no inorganic filler other than mica. Specifically, the content of the inorganic filler other than mica in the mica layer is preferably 3% by mass or less, more preferably 2% by mass or less, and more preferably 1% by mass or less of the total mass of the mica layer. More preferably, it is particularly preferably 0% by mass.

From the viewpoint of suppressing a decrease in thermal conductivity, it is preferable that the mica layer does not substantially contain fibrites. Specifically, the content of fibrils in the mica layer is preferably 1% by mass or less of the total mass of the mica layer, more preferably 0.5% by mass or less, and 0.1% by mass. The following is more preferable, and 0% by mass is particularly preferable. In this specification, the fibrit is a fibrous substance mixed so that the mica layer can stand on its own, and examples thereof include organic fibers such as polyamide and polyimide, and inorganic fibers such as glass fibers.

<Mica tape manufacturing method>
The mica tape of this embodiment may be manufactured through any process, and conventionally known manufacturing methods can be applied.

As an example of a method for producing mica tape, a step of preparing a laminate by arranging a backing material on mica paper, a first particle size distribution peak existing in a range of 5 μm or less, and a range of 6 μm or more exist. A step of applying a composition (varnish) containing an inorganic filler containing boron nitride having a second particle size distribution peak and a resin component to the backing material side of the laminate. It is done.

The details and preferred embodiments of the mica, backing material, inorganic filler and resin component used in the above method, and the produced mica tape are as described above. The mica paper is a sheet-like object formed by collecting mica pieces.

If necessary, the composition may contain a solvent. By including the solvent, the viscosity of the composition is lowered, and the inorganic filler tends to be easily mixed. The type of the solvent is not particularly limited, and can be selected from commonly used organic solvents. Specific examples include methyl ethyl ketone, toluene, methanol, cyclohexanone and the like. A solvent may be used individually by 1 type, or may use 2 or more types together.

The content of the inorganic filler in the composition is not particularly limited. For example, it is preferably 20% by volume to 90% by volume, and more preferably 25% by volume to 35% by volume of the total nonvolatile content (components excluding the solvent) of the composition. When the content of the inorganic filler is 20% by volume or more of the entire nonvolatile content of the composition, the thermal conductivity of the insulating layer formed using mica tape tends to be further improved. When the content of the inorganic filler is 90% by volume or less of the entire nonvolatile content of the composition, the mixing property of the inorganic filler and the resin component tends to be improved.

The viscosity at the time of application of the composition is not particularly limited. For example, it is preferably 500 mPa · s to 3000 mPa · s. The viscosity at the time of application of the composition is a temperature of the composition when the composition is applied to the backing material, and is a value measured using an E-type viscometer under a condition of 50 revolutions / minute (rpm). The application of the composition can be performed, for example, by applying the composition to the backing material using a roll coater or the like.

It is preferable to apply the composition so that the composition applied to the backing material oozes out to the other surface side of the backing material and penetrates all or part of the mica paper. In this case, even if it is not a fibrotic mixed paper, the mica paper can easily become independent and is not easily collapsed. By using mica paper that does not contain fibrites, the thermal conductivity tends to be improved.

The mica tape of this embodiment can be used, for example, for forming an insulating layer provided on the outer periphery of an insulator such as a coil conductor used for a rotating electrical machine coil or the like.

<Hardened mica tape>
The cured product of the mica tape of this embodiment is obtained by curing the mica tape described above. More specifically, it is obtained by curing a resin component contained in a mica tape. The curing method is not particularly limited, and can be selected from ordinary methods.

<Insulator>
The insulator of this embodiment includes an insulator and an insulating layer that is a cured product of the mica tape of this embodiment that is disposed on at least a part of the surface of the insulator. The method for forming the insulating layer using the mica tape of the present embodiment is not particularly limited, and conventionally known production methods can be applied. For example, after winding mica tape around an insulator, heat it while applying pressure to the mica tape (heat press), and let the resin component contained in the mica tape flow out of the mica tape in advance and overlap between the overlapping mica tapes. A resin component is formed by filling and curing an insulating layer (in the case of a prepreg mica tape), winding a mica tape around an insulator, and then applying a vacuum pressure impregnation (VPI). A method of impregnating a mica tape and curing the same to form an insulating layer (in the case of dry mica tape).

When the insulating layer is formed by the vacuum pressure impregnation method, the resin component impregnated into the mica tape is not particularly limited. For example, what contains epoxy resins, such as a bisphenol A type epoxy resin, and hardening | curing agents, such as an alicyclic acid anhydride, is mentioned. For the impregnation method of the resin component in the vacuum pressure impregnation method, the curing conditions after the impregnation, the ratio of the epoxy resin and the curing agent, etc., conventionally known methods, known conditions and the like can be referred to.

The kind of insulator to be insulated is not particularly limited, and examples thereof include metal materials (copper, etc.) having shapes such as coils, rods, and plates. Specific examples of the insulator include a coil conductor of a coil for a rotating electrical machine.

By using the mica tape of this embodiment, an insulating layer exhibiting high thermal conductivity can be formed. Therefore, when the insulator of this embodiment is a coil, when cooling the coil, a hydrogen cooling method or an air cooling method should be adopted even for a coil of a scale that conventionally employs a direct water cooling method. As a result, the coil structure can be simplified.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples.

<Example 1>
(1) Production of mica paper Unfired hard mica was dispersed in water to form mica particles, and the mica was made with a paper machine to produce mica paper having a mica amount of 140 g / m ² .

(2) Preparation of boron nitride-containing varnish 13.1% by mass of a bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, “Epicoat 828”) as a resin component and zinc (II) acetylacetonate (Junsei Co., Ltd.) as a curing catalyst ) 3.3% by mass and 46.0% by mass of methyl ethyl ketone (Wako Pure Chemical Industries, Ltd.) as a solvent were mixed. Thereafter, 37.6% by mass of boron nitride (Electrochemical Industry Co., Ltd.) having a particle size distribution peak in the range of 2 μm to 3 μm and in the range of 7 μm to 9 μm is added and stirred, and boron nitride containing boron nitride as an inorganic filler A containing varnish was prepared. The particle size distribution of the boron nitride used is shown in FIG. The particle size distribution of boron nitride was D10 = 2.9 μm, D50 = 6.5 μm, D90 = 13.0 μm.
The particle size distribution of boron nitride was measured by a laser diffraction method using Nikkiso Co., Ltd. “Microtrack MT3000II”). Specifically, 10 mg of boron nitride was added to 50 mg of pure water and dispersed by shaking for 10 minutes. 20 ml was injected into the cell and measured at 25 ° C. The refractive index of water was 1.333, and the refractive index of boron nitride was 2.17.
The ratio by mass of the epoxy resin and the curing catalyst in the boron nitride-containing varnish (epoxy resin: curing catalyst) was 97: 3.
As the viscosity at the time of application of the obtained boron nitride-containing varnish, the viscosity (mPa · s) at 25 ° C. and 50 revolutions / minute (rpm) was measured using an E-type viscometer. The results are shown in Table 1.

(3) Production of mica tape A glass cloth (Soyo Co., Ltd., “WEA 03G 103”, total volume of interstices: 24.4 cm ³ / m ² ) is laminated on mica paper and prepared on the glass cloth. The boron nitride-containing varnish was applied using a roll coater. The application was performed so that the resin component penetrated into the mica paper under the glass cloth. After drying, the laminate of mica paper and glass cloth was cut to a width of 30 mm to produce a mica tape having a mica layer and a backing layer.
The average thickness of the obtained mica tape was measured at 10 points using a micrometer (Mitutoyo Co., Ltd., “MDC-SB”) and obtained as the arithmetic average value. The results are shown in Table 1.

(4) Production of laminated cured product of mica tape The above mica tape was layered on 25 layers and immersed in an impregnating varnish, and the impregnating varnish was infiltrated into the mica tape by a vacuum impregnation method. Thereafter, the resin component was cured by heat pressing at 130 ° C. for 2 hours and then at 190 ° C. for 2 hours to prepare a laminated cured product. At this time, the presence or absence of boron nitride outflow was visually confirmed, and no visible outflow occurred.
As the impregnating varnish, bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, “Epicoat 828”) and a curing agent (Hitachi Chemical Co., Ltd., “HN-5500”, methylhexahydrophthalic anhydride) are used on a mass basis. What was mixed in 1 was used.
About the produced laminated cured product, thermal conductivity (W / (m · K)) was measured using a thermal conductivity measuring device (Hideko Seiki Co., Ltd., “HC-110”). The results are shown in Table 1.

(5) Measurement of the amount of boron nitride in mica tape The mica tape is heated in an electric furnace at 600 ° C. for 2 hours, and the mass of the resin component as a decrease from the mass before and after the heating, and the inorganic as the residual The mass of the components (boron nitride, mica and glass cloth) was calculated. Furthermore, the amount of boron nitride was calculated by subtracting the mass of the mica and glass cloth used for the production of the mica tape from the mass of the remaining portion. The results are shown in Table 1.

<Example 2>
(1) Production of mica paper Unfired hard mica was dispersed in water to form mica particles, and the paper was made with a paper machine to produce mica paper having a mica amount of 180 g / m ² .

(2) Preparation of boron nitride-containing varnish Epoxy novolak resin (Dow Chemical Japan Co., Ltd., trade name “D.N.438” (“D.N.” is a registered trademark)) 36 as a resin component 0.7% by mass, 1.1% by mass of boron trifluoride monoethylamine (Wako Pure Chemical Industries, Ltd.) as a curing accelerator, and 31.1% by mass of methyl ethyl ketone (Wako Pure Chemical Industries, Ltd.) as a solvent did. Thereafter, 31.1% by mass of boron nitride (Electrochemical Co., Ltd.) having a particle size distribution peak in the range of 2 μm to 3 μm and in the range of 7 μm to 9 μm was added and further mixed to prepare a boron nitride-containing varnish. The particle size distribution of boron nitride was D10 = 1.1 μm, D50 = 5.2 μm, and D90 = 14.5 μm.

(3) Production of mica tape A glass cloth (Soyo Co., Ltd., “WEA 03G 103”, total volume of interstices: 24.4 cm ³ / m ² ) is laminated on mica paper and prepared on the glass cloth. The boron nitride-containing varnish was applied using a roll coater. The application was performed so that the resin component penetrated into the mica paper under the glass cloth. After drying, the laminate of mica paper and glass cloth was cut to a width of 30 mm to produce a mica tape having a mica layer and a backing layer.
About the obtained mica tape, it carried out similarly to Example 1, and measured average thickness. The results are shown in Table 1.

(4) Production of laminated cured product of mica tape The produced mica tape was stacked on 16 layers, and heat-pressed at 170 ° C. for 1 hour to cure the resin component, thereby producing a laminated cured product. At this time, the presence or absence of boron nitride outflow was visually confirmed, and no visible outflow occurred.
About the obtained laminated hardened | cured material, it carried out similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

<Comparative Example 1>
As the boron nitride used for the preparation of the boron nitride-containing varnish, a mica tape and laminate curing were carried out in the same manner as in Example 1 except that boron nitride having a particle size distribution peak of only 6 μm (Electrochemical Co., Ltd.) was used. A product was prepared and evaluated. The results are shown in Table 1.
Moreover, when the presence or absence of outflow of boron nitride into the impregnating varnish during vacuum impregnation was visually confirmed, the impregnating varnish became cloudy and outflow of boron nitride occurred.

<Comparative example 2>
A mica tape was prepared in the same manner as in Example 2 except that boron nitride (electrochemical industry) having a particle size distribution peak of only 6 μm was used as the boron nitride used for the preparation of the boron nitride-containing varnish. And evaluated. The results are shown in Table 1.
Further, when the mica tape was produced, uneven coating and resin loss occurred, resulting in a non-uniform tape. When a 16-layer laminated cured product of mica tape was produced, the presence or absence of outflow of boron nitride was visually confirmed. As a result, the varnish extruded by the press became cloudy and outflow of boron nitride occurred.

<Comparative Example 3>
Mica tape and lamination hardening were carried out in the same manner as in Example 1 except that boron nitride (Electrochemical Industry Co., Ltd.) having a particle size distribution peak of only 2 μm was used as boron nitride used for the preparation of the boron nitride-containing varnish. A product was prepared and evaluated. The results are shown in Table 1.
Moreover, when the presence or absence of outflow of boron nitride into the impregnating varnish during vacuum impregnation was visually confirmed, the impregnating varnish became cloudy and outflow of boron nitride occurred.

<Comparative example 4>
A mica tape was prepared in the same manner as in Example 2 except that boron nitride (electrochemical industry) having a particle size distribution peak of only 6 μm was used as the boron nitride used for the preparation of the boron nitride-containing varnish. And evaluated. The results are shown in Table 1.
Further, when the mica tape was produced, uneven coating and resin loss occurred, resulting in a non-uniform tape. When a 16-layer laminated cured product of mica tape was produced, the presence or absence of outflow of boron nitride was visually confirmed. As a result, the varnish extruded by the press became cloudy and outflow of boron nitride occurred.

As shown in Table 1, Example 1 using boron nitride having a first particle size distribution peak existing in a range of 5 μm or less and a second particle size distribution peak present in a range of 7 μm or more is a particle size distribution. Good thermal conductivity was achieved even with a small amount of boron nitride as compared with Comparative Example 1 using boron nitride having a peak only at 6 μm. On the other hand, Example 2 using boron nitride having a first particle size distribution peak existing in a range of 5 μm or less and a second particle size distribution peak present in a range of 6 μm or more has a particle size distribution peak of 6 μm. Thermal conductivity was significantly improved with the same amount of boron nitride as in Comparative Example 2 using only boron nitride.

Furthermore, in Comparative Examples 1 and 2, boron nitride flowed into the varnish, whereas in Examples 1 and 2, almost no outflow was observed. The reason for this is that the viscosity of the varnish containing boron nitride prepared in Examples 1 and 2 is lower than that of Comparative Examples 1 and 2 and uneven coating is less likely to occur, so the distribution of nitride filler in the backing layer is uneven. It is conceivable that the nitride filler is sufficiently taken into the backing layer.

From the above, it has been found that according to the present invention, it is possible to form an insulating layer while suppressing the falling off of the inorganic filler from the mica tape. As a result, it was found that an insulating layer having excellent thermal conductivity can be formed while suppressing the amount of inorganic filler.

1 Inorganic filler 2 Backing material 3 Resin component 4 Mica 5 Backing layer 6 Mica layer 7 Boron nitride particles corresponding to the first particle size distribution peak 8 Boron nitride particles corresponding to the second particle size distribution peak

Claims (12)

1. A coil conductor; and an insulating layer disposed on an outer periphery of the coil conductor, wherein the insulating layer includes a mica tape, and the mica tape includes a mica layer including mica, and a backing including a backing material and an inorganic filler. The inorganic filler comprises boron nitride having a first particle size distribution peak present in a range of 5 μm or less and a second particle size distribution peak present in a range of 6 μm or more. Electric coil.
2. 2. The rotating electrical machine according to claim 1, wherein in the mica tape, the first particle size distribution peak of the boron nitride exists in a range of 2 μm to 5 μm, and the second particle size distribution peak exists in a range of 6 μm to 10 μm. coil.
3. 3. The rotating electrical machine according to claim 1, wherein the content of the inorganic filler in the mica tape is 20% by volume to 50% by volume of a total volume of non-volatile components excluding the mica and the backing material. coil.
4. Winding the mica tape around the outer circumference of the coil conductor;
   The method for manufacturing a coil for a rotating electrical machine according to any one of claims 1 to 3, further comprising: forming the insulating layer including the mica tape wound around the outer periphery of the coil conductor.
5. A mica layer containing mica, and a backing layer containing a backing material and an inorganic filler, wherein the inorganic filler has a first particle size distribution peak existing in a range of 5 μm or less and a first particle size distribution peak existing in a range of 6 μm or more. A mica tape comprising boron nitride having a second particle size distribution peak.
6. 6. The mica tape according to claim 5, wherein the first particle size distribution peak of the boron nitride exists in a range of 2 μm to 5 μm, and the second particle size distribution peak exists in a range of 6 μm to 10 μm.
7. The mica tape according to claim 5 or 6, wherein the content of the inorganic filler is 20% by volume to 50% by volume of the total volume of non-volatile components excluding the mica and the backing material.
8. Arranging the backing material on mica and preparing a laminate;
   A composition comprising an inorganic filler containing boron nitride having a first particle size distribution peak present in a range of 5 μm or less and a second particle size distribution peak present in a range of 6 μm or more, and a resin component. And a step of applying to the backing material side of the laminate.
9. The method for producing a mica tape according to claim 8, wherein the content of the inorganic filler in the composition is 20% by volume to 50% by volume of the entire nonvolatile content of the composition.
10. The method for producing mica tape according to claim 8 or 9, wherein the viscosity at the time of application of the composition is 500 mPa · s to 3000 mPa · s.
11. The cured product of mica tape according to any one of claims 5 to 7, comprising a resin component and obtained by curing the resin component.
12. An insulator having an insulator and an insulating layer that is a cured product of the mica tape according to claim 11 disposed on at least a part of a surface of the insulator.

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