JP2014157783A - Electrical insulation sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrical insulation sheet with less deterioration of electrical insulation properties, capable of sufficiently deforming following winding-up onto an electrical conductor, and also capable of maintaining a wound-up state even if kept under comparatively high temperature after wound-up.SOLUTION: An electrical insulation sheet includes a resin layer having a sheet-like resin composition including a resin and an inorganic filler. In the resin layer, a product of its thickness and modulus of elongation is 250 MPa mm or lower, and an insulation life of the resin layer is 200 seconds or longer at applied voltage of 25 kV/mm.

Description

  The present invention relates to an electrical insulating sheet.

  2. Description of the Related Art Conventionally, various types of sheets for electrical insulation are known. For example, a sheet that is bent and processed three-dimensionally is known.

As this type of electrical insulating sheet, for example, a sheet in which an aromatic polyamide paper and a polyester film are laminated is known (Patent Document 1).
The above-mentioned sheet for electrical insulation is, for example, bent into a cylindrical shape and processed three-dimensionally, and an electric conductor as an electric conductor is wound around the processed cylinder and used in a motor or the like.

  Since the above sheet for electrical insulation includes an aromatic polyamide paper and a polyester film, it is excellent in electrical insulation. Moreover, such a sheet for electrical insulation is less likely to be deteriorated by heat accompanying current flowing through the electric wire as the electrical conductor, and is less likely to deteriorate in electrical insulation over time.

JP 2008-263704 A

  By the way, as an electric conductor for flowing an electric current, not only an electric wire but plate-like things, such as a bus bar, are known. Therefore, it is desired to use an electrical insulating sheet wrapped around a plate-like electrical conductor.

However, the above-mentioned sheet for electrical insulation in which an aromatic polyamide paper and a polyester film as described in Patent Document 1 are laminated, for example, when wound around a plate-like electrical conductor, It has a problem that it cannot always be sufficiently deformed following the shape.
In addition, although the above-mentioned sheet for electrical insulation has little decrease in electrical insulation over time, when it is placed at a relatively high temperature after winding, the deformed state after winding cannot always be maintained, and the electric conductor And a problem that a space may be generated between the electrical insulating sheet and the electrical conductor.
When a current flows through the electrical conductor with a space between the electrical insulating sheet and the electrical conductor, a discharge phenomenon occurs between the electrical insulating sheet and the electrical conductor, and the electrical insulation is caused by the discharge. The sheet for use deteriorates and the strength of the sheet for electrical insulation decreases.

  The present invention has been made in view of the above-mentioned problems and the like, the decrease in electrical insulation is reduced, and it can be sufficiently deformed following winding around an electric conductor, and compared after winding. It is an object of the present invention to provide an electrical insulating sheet that can maintain a wound state even when placed under a high temperature.

  The sheet for electrical insulation of the present invention comprises a resin layer in which a resin composition containing a resin and an inorganic filler is formed into a sheet shape, and the product of the thickness of the resin layer and the tensile elastic modulus is 250 MPa · mm or less. The insulating life of the resin layer at an applied voltage of 25 kV / mm is 200 seconds or longer.

  In the electrical insulating sheet of the present invention, the resin is at least one selected from the group consisting of a polysulfone resin, a polyarylene sulfide resin, a polyimide resin, and a polyamide resin, and the inorganic filler is a metal hydroxide. Or it is preferable that it contains a metal carbonate.

  In the sheet for electrical insulation of the present invention, the isoelectric point of the inorganic filler is preferably 7 or more.

  In the sheet for electrical insulation of the present invention, the inorganic filler preferably has an average particle size of 500 nm or less.

  In the electrical insulating sheet of the present invention, it is preferable that the metal hydroxide or the metal carbonate causes an endothermic decomposition reaction at a temperature exceeding 330 ° C.

  The sheet for electrical insulation of the present invention preferably further comprises a sheet-like adhesive layer having adhesiveness than the resin layer, and the adhesive layer is preferably disposed on at least one side of the resin layer.

  In the electrical insulating sheet of the present invention, the adhesive layer is at least one selected from the group consisting of acrylic resins, rubber resins, silicone resins, polyester resins, polyurethane resins, and epoxy resins. It is preferable to contain.

  The electrical insulation sheet of the present invention preferably has a product of thickness and tensile elastic modulus of 350 MPa · mm or less, and an insulation life of 200 seconds or more at an applied voltage of 25 kV / mm.

  The electrical insulating sheet of the present invention is preferably used by being wound around a bus bar.

  The electrical insulating sheet of the present invention is preferably used by being wound around a bus bar in a converter or an inverter.

  The electrical insulating sheet according to the present invention has less deterioration in electrical insulation, and can be sufficiently deformed following winding around an electric conductor, and can be placed at a relatively high temperature after winding. There is an effect that the wound state can be maintained.

Sectional drawing which showed typically the cross section which cut | disconnected the sheet | seat for electrical insulation provided only with the resin layer in the thickness direction. Sectional drawing which showed typically the cross section which cut | disconnected the sheet | seat for electrical insulation provided with the resin layer and the adhesion layer in the thickness direction. The figure which represented the mode of evaluation of the sheet | seat for electrical insulation typically.

  Hereinafter, an embodiment of an electrical insulating sheet according to the present invention will be described with reference to the drawings. FIG.1 and FIG.2 is sectional drawing which showed typically the cross section which cut | disconnected the sheet | seat for electrical insulation of this embodiment in the thickness direction.

  The sheet for electrical insulation 1 of this embodiment includes a resin layer 2 in which a resin composition containing a resin and an inorganic filler is formed into a sheet shape, and the product of the thickness of the resin layer 2 and the tensile elastic modulus is 250 MPa · The insulation life of the resin layer 2 at an applied voltage of 25 kV / mm is 200 seconds or longer.

Since the product of the thickness of the resin layer and the tensile elastic modulus is 250 MPa · mm or less, the electrical insulating sheet 1 can be sufficiently deformed as it is wound around the electrical conductor. Moreover, the electrically insulating sheet 1 can maintain the wound state even when placed at a relatively high temperature after being wound.
In addition, since the electrical insulation sheet 1 has an insulation life of 200 seconds or more at an applied voltage of 25 kV / mm of the resin layer 2, there is little decrease in electrical insulation.

The shape of the resin layer 2 is not particularly limited as long as it is formed in a sheet shape.
The thickness of the resin layer 2 is not particularly limited, and is usually 1 μm to 500 μm.
The thickness of the resin layer 2 is measured using a dial gauge. Further, the thickness of the resin layer 2 is determined by the average value of the five measured values in the resin layer 2.

The tensile elastic modulus of the resin layer 2 is usually 500 to 5000 MPa.
The tensile elastic modulus of the resin layer 2 is preferably 800 MPa or more, and more preferably 1000 MPa or more. When the tensile elastic modulus of the resin layer 2 is 500 MPa or more, there is an advantage that the strength of the electrical insulating sheet becomes more sufficient.
The tensile elastic modulus of the resin layer 2 is preferably 4500 MPa or less, and more preferably 4000 MPa or less. When the tensile elastic modulus of the resin layer 2 is 5000 MPa or less, there is an advantage that the electrical insulating sheet can be more sufficiently deformed as it is wound around a covering object such as an electrical conductor.

  The tensile elastic modulus of the resin layer 2 is measured in accordance with JIS K7161 at 23 ° C. under a tensile speed of 200 mm / min and a tensile line of 50 mm.

The tensile elastic modulus of the resin layer 2 can be increased, for example, by increasing the mass ratio of the inorganic filler to the resin in the resin composition. On the other hand, the tensile elastic modulus of the resin layer 2 can be reduced, for example, by lowering the mass ratio of the inorganic filler to the resin in the resin composition.
Moreover, the tensile elastic modulus of the resin layer 2 can be increased, for example, by increasing the mass ratio of a crystalline resin (polyamide resin or the like) in the resin composition, or by stretching the resin layer 2.

The product of the thickness of the resin layer 2 and the tensile elastic modulus is preferably 200 MPa · mm or less, and more preferably 150 MPa · mm or less. There exists an advantage that the sheet | seat for electrical insulation can deform | transform more fully because the product of the thickness of the resin layer 2 and a tensile elasticity modulus is 200 Mpa * mm or less.
The product of the thickness of the resin layer 2 and the tensile elastic modulus is usually 100 MPa · mm or more.

The insulation life of the resin layer 2 at an applied voltage of 25 kV / mm is preferably 250 seconds or more, and more preferably 300 seconds or more. When the insulation life is 250 seconds or more, there is an advantage that the electrical insulation is less deteriorated.
The insulation life of the resin layer 2 at an applied voltage of 25 kV / mm is usually 2000 seconds or less.

  The insulation life of the resin layer 2 is measured at an applied voltage of 25 kV / mm, and specifically measured by the method described in the examples.

  The insulation life of the resin layer 2 can be lengthened, for example, by increasing the mass ratio of the inorganic filler to the resin in the resin composition.

  The resin blended in the resin composition is preferably at least one selected from the group consisting of a polysulfone resin, a polyarylene sulfide resin, a polyimide resin, and a polyamide resin.

The polysulfone resin is a thermoplastic resin having a molecular structure including a plurality of sulfonyl groups (—SO ₂ —).
Examples of the polysulfone resin include a polyethersulfone resin further including a plurality of ether bonds (—O—) in the molecule, or a polyphenylsulfone resin further including a plurality of aromatic hydrocarbons in the molecule. Moreover, as this polysulfone resin, the polyether polyphenyl sulfone resin which further contains a some ether bond and a some aromatic hydrocarbon in a molecule | numerator is mentioned.

  As the polysulfone resin, the polysulfone resin is more excellent in moldability of the resin composition, and the heat resistance of the resin layer 2 molded with the resin composition is more excellent. The ether sulfone resin or the polyphenyl sulfone resin is preferable, and the polyether polyphenyl sulfone (PES) resin is more preferable.

  As said polyether polyphenyl sulfone (PES) resin, what has the molecular structure of following formula (1) is preferable.

  As said polyether polyphenyl sulfone resin, what is marketed is employ | adopted, for example. Examples of commercially available polyether polyphenylsulfone resins include “Ultrazone E series” manufactured by BASF, “Radel A series” manufactured by Solvay, and “Sumika Excel series” manufactured by Sumitomo Chemical. .

  The polyarylene sulfide resin is a thermoplastic resin having a plurality of arylene groups and a plurality of sulfide bonds in the molecule. The arylene group is a divalent group of arene (monocyclic or polycyclic aromatic hydrocarbon). Specific examples of the arylene group include a phenylene group, a naphthylene group, an anthrylene group, a phenanthrylene group, and a pyrenylene group.

  The polyarylene sulfide resin is preferably a polyphenylene sulfide (PPS) resin having a plurality of phenylene groups and a plurality of sulfide bonds (—S—) in the molecule. When the polyarylene sulfide resin is a polyphenylene sulfide (PPS) resin, there is an advantage that the electrical insulation of the resin layer 2 becomes more excellent.

The polyimide resin is a thermoplastic resin having a plurality of imide bonds in the molecule.
As the polyimide resin, a polyetherimide (PEI) resin having a plurality of aromatic hydrocarbons, imide bonds and ether bonds in the molecule, or a thermoplastic having a plurality of imide bonds and a plurality of amide bonds in the molecule. Polyamideimide resin is preferred.

  The polyamide resin is a thermoplastic resin obtained by polymerizing at least a polyamine compound and a polycarboxylic acid compound by dehydration condensation.

  Examples of the polyamide resin include a polyamide resin having an aromatic hydrocarbon in the molecule and an aliphatic polyamide resin having only an aliphatic hydrocarbon as a hydrocarbon in the molecule. Especially, the polyamide resin which has an aromatic hydrocarbon in a molecule | numerator is preferable at the point that the resin layer 2 can become what was excellent in heat resistance, while being excellent in electrical insulation.

The polyamide resin having an aromatic hydrocarbon in the molecule includes an aromatic polyamide resin having only an aromatic hydrocarbon as a hydrocarbon in the molecule, an aliphatic hydrocarbon and an aromatic hydrocarbon as a hydrocarbon in the molecule. Examples thereof include semi-aromatic polyamide resins having both.
As the polyamide resin having an aromatic hydrocarbon in the molecule, the semi-aromatic polyamide resin is preferable in that the resin layer 2 can have excellent mechanical strength while being excellent in electrical insulation.

Specific examples of the polyamine compound used in the polymerization of the polyamide resin include a diamine compound.
Examples of the diamine compound include aliphatic diamines containing linear or branched hydrocarbon groups, alicyclic diamines containing cyclic saturated hydrocarbon groups, and aromatic diamines containing aromatic hydrocarbon groups. .

Examples of the aliphatic diamine, the alicyclic diamine, or the aromatic diamine include those represented by the following formula (2). R ₁ in the following formula (2) represents an aliphatic hydrocarbon group having 4 to 12 carbon atoms or an alicyclic hydrocarbon group having 4 to 12 carbon atoms including a cyclic saturated hydrocarbon, or Represents a hydrocarbon group containing an aromatic ring.
H ₂ N—R ₁ —NH ₂ (2)

As the aliphatic diamine, nonanediamine having 9 carbon atoms in R ₁ in formula (2) is preferable in that the resin composition can be more excellent in mechanical strength, and 1,9-nonanediamine and A mixture of 2-methyl-1,8-octanediamine is more preferable.
Examples of the aromatic diamine include phenylenediamine and xylylenediamine.

Specific examples of the polycarboxylic acid compound used in the polymerization of the polyamide resin include a dicarboxylic acid compound.
Examples of the dicarboxylic acid compound include an aliphatic dicarboxylic acid containing a linear or branched hydrocarbon group, an alicyclic dicarboxylic acid containing a cyclic saturated hydrocarbon group, and an aromatic dicarboxylic acid containing an aromatic hydrocarbon group. Etc.

Examples of the aliphatic dicarboxylic acid, the alicyclic dicarboxylic acid, or the aromatic dicarboxylic acid include those represented by the following formula (3). R ₂ in the following formula (3) represents an aliphatic hydrocarbon group having 4 to 25 carbon atoms, or an alicyclic hydrocarbon group having 4 to 12 carbon atoms including a cyclic saturated hydrocarbon, or Represents a hydrocarbon group containing an aromatic ring.
_{HOOC-R 2 -COOH ··· (3} )

Examples of the aliphatic dicarboxylic acid include adipic acid and sebacic acid.
Examples of the aromatic dicarboxylic acid include terephthalic acid, methyl terephthalic acid, and naphthalene dicarboxylic acid. As the aromatic dicarboxylic acid, terephthalic acid can be used because the heat resistance of the polyamide resin can be further improved. Acid is preferred.

  The polyamide resin may be one obtained by polymerizing one kind of diamine compound and one kind of dicarboxylic acid compound, or may be one obtained by polymerizing a combination of plural kinds of each compound. Good. Further, if necessary, a material obtained by further polymerizing a compound other than the diamine compound and the dicarboxylic acid compound may be used.

  As described above, the polyamide resin is preferably the semi-aromatic polyamide resin. As the semi-aromatic polyamide resin, an aliphatic diamine as a diamine compound and an aromatic dicarboxylic acid as a dicarboxylic acid compound are polymerized. More preferred are those obtained by polymerizing nonanediamine as an aliphatic diamine and terephthalic acid as an aromatic dicarboxylic acid (PA9T).

  As said polyamide resin, what is marketed is employ | adopted, for example. Specifically, examples of commercially available polyamide resins include “Genester” series manufactured by Kuraray Co., Ltd.

The resin composition preferably contains 50% by mass or more, preferably 60% by mass or more, of at least one thermoplastic resin selected from the group consisting of a polysulfone resin, a polyarylene sulfide resin, a polyimide resin, and a polyamide resin. It is more preferable. When the resin composition contains such a thermoplastic resin in an amount of 50% by mass or more, there is an advantage that the resin layer 2 is more easily deformed and the modification accompanying the winding of the resin layer 2 is easier.
The resin composition preferably includes 90% by mass or less of at least one thermoplastic resin selected from the group consisting of polysulfone resin, polyarylene sulfide resin, polyimide resin, and polyamide resin, and 85% by mass. It is more preferable to include the following. When the resin composition contains 90% by mass or less of such a thermoplastic resin, the mechanical strength of the resin layer 2 is further improved, and there is an advantage that the deterioration of insulation due to discharge in the resin layer 2 is further suppressed.

The resin composition preferably contains 5% by mass or more of the polyamide resin, more preferably 10% by mass or more. When the resin composition contains 5% by mass or more of the polyamide resin, there is an advantage that the mechanical strength and creeping insulation of the resin layer 2 can be further improved.
Moreover, it is preferable that the said resin composition contains the said polyamide resin 50 mass% or less, It is more preferable that 40 mass% or less is included, It is further more preferable that 30 mass% or less is included. When the resin composition contains 50% by mass or less of the polyamide resin, there is an advantage that the discharge deterioration of the resin layer 2 is further suppressed.

  The resin composition preferably includes the polysulfone resin and the polyamide resin in a mass ratio of polysulfone resin / polyamide resin = 60/40 to 90/10. By including the polysulfone resin and the polyamide resin at a mass ratio in such a range, there is an advantage that the mechanical strength and heat resistance of the resin layer 2 become more excellent.

The resin composition may contain other thermoplastic resins in addition to the thermoplastic resins described above.
As the other thermoplastic resin, for example, a polyacetal (POM) resin having a plurality of oxymethylene (—CH ₂ O—) groups in the molecule; a basic structure of an aromatic hydrocarbon-ether bond is repeated in the molecule. Polyphenylene oxide (PPO) resin such as polyphenylene ether (PPE) resin; aromatic polyether ketone (PEK) in which the basic structure of aromatic hydrocarbon-ether bond-aromatic hydrocarbon-ketone bond is repeated in the molecule ) Resin; Aromatic polyether ketone (PEEK) resin in which the basic structure of aromatic hydrocarbon-ether bond-aromatic hydrocarbon-ether bond-aromatic hydrocarbon-ketone bond is repeated in the molecule; polyethylene, polypropylene Polyolefin resins such as polycycloolefins; acrylonitrile and butadiene Aromatic-containing vinyl resins such as copolymers with ABS (ABS resin); Polyester resins such as polyethylene naphthalate (PEN) resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin; Polycarbonate (PC) Resin; liquid crystal polymer (LCP); thermoplastic elastomer resin and the like.

  The said inorganic filler is an inorganic compound by which the insulation lifetime of the resin layer 2 is lengthened by mix | blending with the said resin composition rather than the time of not containing an inorganic filler.

When a relatively high voltage is applied to the electrical insulating sheet, a discharge phenomenon (hereinafter also referred to as partial discharge) may occur in a part of the resin composition constituting the resin layer 2. The charged particles generated by the partial discharge can collide with the molecular chains of the resin contained in the resin composition to break the molecular chains, or thermally decompose the molecular chains by heat accompanying the collision. Moreover, ozone is generated by partial discharge, and the ozone can cause deterioration of the resin contained in the resin composition. Along with such a phenomenon, it is considered that the fracture path extends in the resin layer 2 and the electrical insulation of the resin layer 2 can be lowered.
On the other hand, since the resin composition of the resin layer 2 includes an inorganic filler, the above-described elongation of the fracture path can be hindered by the individual inorganic filler. Therefore, the resin layer 2 can be less deteriorated in electrical insulation.

In the resin layer 2, it is preferable that an average particle diameter of the inorganic filler is 500 nm or less.
When the average particle diameter of the inorganic filler in the resin layer 2 is 500 nm or less, the number of inorganic fillers per unit mass of the inorganic filler is relatively large. As the number of inorganic fillers increases, the elongation of the fracture path described above is more easily prevented by the individual inorganic fillers.
Therefore, when the average particle diameter of the inorganic filler is 500 nm or less, the electrical insulating sheet can be less deteriorated in electrical insulation.

  The average particle diameter of the inorganic filler is preferably 10 nm or more. When the average particle size is 10 nm or more, there is an advantage that the aggregation of the inorganic filler in the resin composition is further suppressed and the inorganic filler is more easily dispersed in the resin composition.

The average particle diameter of the inorganic filler is a value determined by the following method.
That is, the average particle diameter of the inorganic filler is the primary particle diameter of 1000 inorganic fillers in an observation image (magnification: 10,000 times) obtained with a scanning electron microscope (Hitachi High-Tech, product name “S-3400N”). Calculate by averaging. Specifically, the observation image is obtained by analyzing the horizontal ferret diameter by image analysis software (product name “A image kun” manufactured by Asahi Kasei Engineers), and determining and averaging the horizontal ferret diameter of each inorganic filler.
In order to obtain an observation image, an inorganic filler is dispersed in acetone so as to have a concentration of 0.1% by mass, and a dispersion is prepared. After the dispersion is dropped onto a glass plate, the acetone is evaporated and dried. A sample is prepared. And the average particle diameter of an inorganic filler is calculated | required by observing this sample for observation.

The inorganic filler preferably contains a metal hydroxide or a metal carbonate. When the inorganic filler contains a metal hydroxide or a metal carbonate, deterioration of the resin composition is suppressed even under high temperature conditions due to application of voltage.
Specifically, when the metal hydroxide exceeds a predetermined temperature, the metal hydroxide decomposes by releasing water molecules while absorbing heat. Similarly, when the metal carbonate exceeds a predetermined temperature, it dissociates by releasing carbon dioxide while absorbing heat. As described above, when the metal hydroxide and the metal carbonate exceed a predetermined temperature, they undergo an endothermic decomposition reaction that decomposes while absorbing heat. Therefore, when an inorganic filler containing a metal hydroxide or metal carbonate is present in the resin composition, the temperature rises due to an endothermic decomposition reaction of the metal hydroxide or metal carbonate under a high temperature condition exceeding a predetermined temperature. Is suppressed. Thereby, deterioration by the heat | fever of the resin layer 2 shape | molded with the resin composition is suppressed, and the fall of the electrical insulation of the resin layer 2 accompanying a heat deterioration will become few. Therefore, the electrical insulating sheet of the present embodiment can be less deteriorated in electrical insulation by employing an inorganic filler containing a metal hydroxide or a metal carbonate.

The metal hydroxide or the metal carbonate preferably undergoes an endothermic decomposition reaction at a temperature exceeding 330 ° C. Since the metal hydroxide or the metal carbonate causes an endothermic decomposition reaction at a predetermined temperature exceeding 330 ° C., there is an advantage that a decrease in electrical insulation of the resin layer 2 can be further reduced.
Specifically, in the production of the resin layer 2, the above-described resin and inorganic filler are usually heated and mixed at a temperature of 280 to 320 ° C. Therefore, a metal hydroxide or metal carbonate that undergoes an endothermic decomposition reaction at a temperature exceeding 330 ° C. does not cause an endothermic decomposition reaction even in the above temperature range in production. And the temperature at which the temperature of a part of the resin composition constituting the resin layer 2 exceeds 330 ° C. and causes an endothermic decomposition reaction of the metal hydroxide or metal carbonate due to the voltage at the time of use of the sheet for electrical insulation. If it becomes above, a metal hydroxide or metal carbonate will raise | generate an endothermic decomposition reaction, and a temperature rise will be suppressed. That is, as the endothermic decomposition reaction occurs, the temperature rise of the resin composition is suppressed, and the thermal deterioration of the resin composition is suppressed. As described above, the electrical insulating sheet according to the present embodiment reduces the electrical insulating property by adopting an inorganic filler containing a metal hydroxide or a metal carbonate that undergoes an endothermic decomposition reaction at a predetermined temperature exceeding 330 ° C. Can be less.

  The metal hydroxide or the metal carbonate usually undergoes an endothermic decomposition reaction at a temperature of 800 ° C. or lower.

The temperature at which the endothermic decomposition reaction occurs is determined by measurement by differential thermal-thermogravimetric analysis (TG-DTA).
Specifically, differential thermal-thermogravimetric analysis is performed on the metal hydroxide or metal carbonate while heating at a rate of temperature increase of 10 ° C./min under an inert gas stream. Then, the temperature at which an endothermic peak begins to occur in the differential thermal analysis is observed, and the temperature at which weight reduction starts in the thermogravimetric analysis is observed. From the results, the temperature at which weight loss starts in thermogravimetric analysis is defined as the temperature at which the endothermic decomposition reaction occurs.

More specifically, for example, magnesium hydroxide as a metal hydroxide starts to generate an endothermic peak from 340 ° C. in a differential thermal-thermogravimetric analysis (TG-DTA) under the above conditions. A vertex appears. Magnesium hydroxide begins to lose weight at 340 ° C. Therefore, the temperature at which magnesium hydroxide undergoes an endothermic decomposition reaction is 340 ° C.
Thus, magnesium hydroxide begins to undergo an endothermic decomposition reaction from 340 ° C., decomposes while absorbing heat, and releases water molecules having a relatively large heat capacity.

  If the metal hydroxide or the metal carbonate is a hydrate, in differential thermal-thermogravimetric analysis (TG-DTA), the weight loss due to desorption of hydrated water molecules is regarded as an endothermic decomposition reaction. Not considered.

In the electrical insulating sheet 1 of this embodiment, when at least a polyamide resin is employed as the resin, the isoelectric point of the inorganic filler is preferably 7 or more, more preferably 8 or more, 9 More preferably, it is the above. When the isoelectric point is 7 or more, there is an advantage that the dispersibility of the inorganic filler in the resin composition is further improved.
Further, when at least a polyamide resin is employed as the resin, it is preferable that the inorganic filler has an isoelectric point of 12 or less. When the isoelectric point is 12 or less, there is an advantage that the dispersibility of the inorganic filler in the resin composition is further improved.

Regarding the relationship between the isoelectric point of the inorganic filler and the dispersibility of the inorganic filler in the resin composition, the surface charge state of the inorganic filler with the isoelectric point of the inorganic filler as an index, and the polyamide that can be contained in the resin composition This can be explained based on the interaction with the amide bond of the resin.
Specifically, the inorganic filler usually has a hydroxyl group that is a polar group on the surface. And the aspect of a hydroxyl group changes according to the surrounding pH environment in an inorganic filler. Specifically, assuming that the inorganic filler is present in water, when the pH of the water is lower than the isoelectric point of the inorganic filler, the form of the hydroxyl group on the surface of the inorganic filler changes and the surface charge becomes positive. On the other hand, when the pH of water is higher than the isoelectric point of the inorganic filler, the surface charge of the inorganic filler becomes negative. Thus, the surface charge of the inorganic filler can vary depending on the surrounding pH environment.
In the resin composition, not only the inorganic filler but also the polyamide resin is present in a dispersed state. Since the polyamide resin has an amide bond, it has a relatively high polarity and exhibits neutral to weak basicity.

In the state where the polyamide resin and the inorganic filler coexist, the inorganic filler exists in a neutral to weakly basic environment due to the polyamide resin, and the surface of the inorganic filler is positively charged by the isoelectric point of the inorganic filler. It can be negatively charged or uncharged. Therefore, an inorganic filler having an isoelectric point of about 2 is positively charged in the presence of a neutral to weakly basic polyamide resin, while an inorganic filler having an isoelectric point of about 8 is neutral to In the presence of a polyamide resin exhibiting weak basicity, the surface may be hardly charged. An inorganic filler having an isoelectric point of about 11 can be negatively charged on the surface in the presence of a polyamide resin, but the difference between the weak basicity exhibited by the polyamide resin and the isoelectric point is relatively small. Therefore, an inorganic filler having an isoelectric point of about 11 is considered to be in a relatively weak charged state even when charged.
From this, when the isoelectric point of the inorganic filler is 7 or more (alkali side), the inorganic filler in the coexistence with the polyamide resin can have a relatively small surface charge. Therefore, the polarity of the inorganic filler due to the surface charge becomes relatively small, and the interaction (hydrogen bond or the like) caused by the polarity of the inorganic filler and the polarity of the polyamide resin can be further reduced. That is, the ionic bond between the inorganic filler and the polyamide resin can be suppressed. Therefore, adsorption of the inorganic filler to the polyamide resin in the resin composition is suppressed, and as a result, the dispersibility of the inorganic filler becomes more excellent.

  The isoelectric point of the inorganic filler is measured according to JIS R1638 “4.1 Electrophoresis b) Electrophoretic Laser Doppler Method”.

The hardness of the inorganic filler is not particularly limited, but is preferably 7 or less in Mohs hardness.
The Mohs hardness is determined by evaluating using 10 kinds of standard minerals. Specifically, the standard mineral is scratched with an inorganic filler to check whether the standard mineral is damaged. That is, the standard mineral is sequentially changed from the standard mineral having the lowest hardness to the standard mineral having the highest hardness, and the hardness of the standard mineral causing the scratch is defined as the Mohs hardness.

The metal hydroxide is preferably magnesium hydroxide, calcium hydroxide, or barium hydroxide. When the metal hydroxide is magnesium hydroxide, calcium hydroxide, or barium hydroxide, there is an advantage that a decrease in electrical insulation of the resin layer 2 molded from the resin composition can be further reduced.
The temperature at which the endothermic decomposition reaction of magnesium hydroxide occurs is 340 ° C., the temperature at which the endothermic decomposition reaction of calcium hydroxide occurs is 580 ° C., and the temperature at which the endothermic decomposition reaction of barium hydroxide occurs is 780 ° C. It is.

The metal carbonate is preferably calcium carbonate or magnesium carbonate. When the metal carbonate is calcium carbonate or magnesium carbonate, there is an advantage that the electrical insulating property of the resin layer 2 molded with the resin composition can be further reduced.
The temperature at which the endothermic decomposition reaction of calcium carbonate occurs is 600 ° C., and the temperature at which the endothermic decomposition reaction of magnesium carbonate (anhydride) occurs is 500 ° C.

The content of the inorganic filler in the resin composition is preferably 1% by mass or more, and more preferably 4% by mass or more. The content of the inorganic filler in the resin composition is preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 6% by mass or less.
When the content ratio of the inorganic filler is 1% by mass or more, there is an advantage that the decrease in electrical insulation of the resin layer 2 molded from the resin composition can be reduced. Moreover, when the content rate of an inorganic filler is 20 mass% or less, there exists an advantage that the mechanical strength of a resin composition can become more excellent.

  The ratio of the resin and the inorganic filler in the resin composition is preferably 1 to 10 parts by mass, more preferably 3 to 7 parts by mass with respect to 100 parts by mass of the resin. When the inorganic filler is 1 to 10 parts by mass with respect to 100 parts by mass of the resin, the decrease in the electrical insulation of the electrical insulating sheet is reduced, and the electrical insulating sheet follows the winding around the electrical conductor. The advantage is that it can be more fully deformed.

In the resin layer 2, it is preferable that aggregation of inorganic fillers in the resin composition is suppressed. That is, the aggregation degree of the aggregated particles of the inorganic filler in the resin layer 2 is preferably 500 nm or less, and more preferably 350 nm or less.
When the agglomeration degree of the agglomerated particles of the inorganic filler is 500 nm or less, there is an advantage that the elongation of the fracture path due to the voltage as described above is further suppressed, and the electrical insulation property of the electrical insulation sheet is further reduced. Moreover, since the aggregation degree of the aggregated particle of an inorganic filler is 500 nm or less, the aggregated particle becomes relatively small. Therefore, there is an advantage that the resin composition starting from the aggregated particle is hardly broken. That is, there is an advantage that the mechanical strength of the resin layer 2, specifically, the tear resistance of the resin layer 2 becomes better.

The degree of aggregation of the above-described inorganic filler aggregated particles in the resin layer 2 is determined by the following method.
That is, the resin layer 2 is cut in the thickness direction along the MD direction, and the cross section thereof is observed with a scanning electron microscope (manufactured by Hitachi High-Tech Co., Ltd., device name “S-3400N”). obtain. Further, the image data is analyzed by image analysis software (product name “A Image-kun”, manufactured by Asahi Kasei Engineers).
Specifically, the degree of aggregation of the aggregated particles of the inorganic filler is measured by the method described in the examples.
In addition, the aggregation degree of the aggregated particles of the inorganic filler in the resin composition is different from the measurement method of the average particle diameter of the inorganic filler, and therefore the average particle diameter (average primary particle diameter) of the inorganic filler is not necessarily larger. Is not limited.

The inorganic filler may be subjected to a surface treatment.
Examples of the surface treatment agent for the surface treatment include organic silane compounds. Examples of the organic silane compound include vinyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, p-styryltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, Examples include 3-acryloxypropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. For example, 0.01 to 5 parts by weight of the surface treatment agent can be used with respect to 100 parts by weight of the inorganic filler that is not surface-treated.

Various additives may be blended in the resin composition constituting the resin layer 2.
Examples of the additives include alkylphenol resins, alkylphenol-acetylene resins, xylene resins, coumarone-indene resins, terpene resins, rosin and other tackifiers, brominated flame retardants such as polybromodiphenyl oxide and tetrabromobisphenol A, Chlorinated flame retardants such as chlorinated paraffin and perchlorocyclodecane, phosphorus flame retardants such as phosphate esters and halogenated phosphate esters, boron flame retardants, oxide flame retardants such as antimony trioxide, phenolic, Inorganic fillers including phosphorous and sulfur antioxidants, silica, clay, aluminum oxide, magnesium oxide, boron nitride, silicon nitride, or aluminum nitride, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, pigments , Crosslinking agent, crosslinking aid, silane coupling agent, titanate Including general plastic compounding ingredients such as coupling agents and the like. Moreover, aromatic polyamide fibers, montmorillonite having a particle size of several nm to several hundred nm, and the like can be mentioned. These additives may be contained in the resin composition, for example, 0.1 to 5% by mass.

  As shown in FIG. 2, the electrical insulating sheet 1 of the present embodiment further includes a sheet-like adhesive layer 3 that is more adhesive than the resin layer 2, and the adhesive layer 3 includes at least the resin layer 2. It is preferable to arrange on one side, and more preferably on the outermost surface.

  The adhesiveness of the adhesive layer 3 is higher than that of the resin layer 2. The adhesiveness is measured according to JIS Z0237 “Testing method for adhesive tape / adhesive sheet” (14 inclined ball tack).

As shown in FIG. 2, the adhesive layer 3 may be disposed only on one side of the electrical insulating sheet 1, or may be disposed on both sides of the electrical insulating sheet 1.
Since the electrical insulating sheet 1 includes the adhesive layer 3 on the outermost surface, there is an advantage that the adhesive layer 3 can be attached so as to be in contact with the electric conductor.

The thickness of the said adhesion layer 3 is 5-200 micrometers normally.
The thickness of the adhesive layer 3 is preferably 10 μm or more. When the thickness is 10 μm or more, there is an advantage that the adhesiveness of the adhesive layer 3 becomes more excellent.
The thickness of the adhesive layer 3 is preferably 100 μm or less. When the thickness is 100 μm or less, there is an advantage that the adhesive described later can be prevented from protruding from the adhesive layer in a relatively high temperature environment.

The pressure-sensitive adhesive layer 3 includes at least a pressure-sensitive adhesive containing a general polymer.
The pressure-sensitive adhesive contains an acrylic pressure-sensitive adhesive containing an acrylic polymer having (meth) acrylic acid ester as a basic structural unit, a rubber-based pressure-sensitive adhesive containing an elastomeric polymer such as synthetic rubber and natural rubber, and a silicone polymer. Silicone pressure sensitive adhesive, polyester pressure sensitive adhesive containing polyester polymer, polyurethane pressure sensitive adhesive containing polyurethane polymer, and the like.
As the pressure-sensitive adhesive, the acrylic pressure-sensitive adhesive is preferable in that it has excellent adhesion characteristics and weather resistance.

The pressure-sensitive adhesive layer 3 preferably contains a cross-linking agent that can cross-link the polymer in the pressure-sensitive adhesive in that the pressure-sensitive adhesive strength and durability are more excellent.
Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, a melamine crosslinking agent, an oxazoline crosslinking agent, a carbodiimide crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent.

  The adhesive layer 3 is rosin resin, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, copolymer petroleum resin, alicyclic in that adhesive strength and durability are further improved. It is preferable to further include a tackifying resin such as a group petroleum resin, a xylene resin, or an elastomer resin.

  In addition to the above-mentioned pressure-sensitive adhesive and crosslinking agent, the pressure-sensitive adhesive layer 3 is made of rubber, such as flame retardant, dispersant, anti-aging agent, antioxidant, processing aid, stabilizer, antifoaming agent, thickener, pigment, In addition, general additives added to plastics may be included as appropriate as long as the effects of the present invention are not impaired.

  The sheet for electrical insulation 1 of the present embodiment includes, for example, a sheet-like base material disposed between the resin layer 2 and the adhesive layer 3, and between the base material and the resin layer 2, You may further provide the layer comprised similarly to the said adhesion layer 3. As shown in FIG.

Examples of the substrate include paper-based substrates such as paper; fiber-based substrates such as cloths, unemployed cloths, and nets; metal-based substrates such as metal foils and metal plates; plastic-based substrates such as plastic films. Rubber base materials such as rubber sheets; foam base materials such as foam sheets; and the like.
Moreover, as said base material, the laminated base material etc. which laminated | stacked said base material are mentioned. As the laminated base material, those including at least the plastic base material such as a laminate of a plurality of the plastic base materials are preferable.

  Examples of the material of the plastic base material include olefins containing α-olefin as a monomer component such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), and the like. Resin: Polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT); polyvinyl chloride (PVC) resin; vinyl acetate resin; polyphenylene sulfide (PPS) resin Examples thereof include polyamide resins such as polyamide and wholly aromatic polyamide; polyimide resins; polyether ether ketone (PEEK) resins. As the material for the plastic base material, one kind may be used alone, or two or more kinds may be used in combination.

The thickness of the electrical insulating sheet 1 is usually 1 μm to 1000 μm.
The thickness of the electrical insulating sheet 1 is preferably 25 μm or more, and more preferably 50 μm or more. When the thickness is 25 μm or more, there is an advantage that the electrical insulation of the electrical insulating sheet 1 becomes more excellent.
The thickness of the electrical insulating sheet 1 is preferably 300 μm or less, and more preferably 200 μm or less. When the thickness is 300 μm or less, there is an advantage that the follow-up property of the electric insulating sheet 1 to the electric conductor becomes more excellent.
The thickness of the electrical insulating sheet 1 is measured in the same manner as the thickness of the resin layer 2.

In the electrical insulating sheet 1, the product of the thickness and the tensile elastic modulus is preferably 350 MPa · mm or less, and more preferably 250 MPa · mm or less.
The product of the thickness of the electrical insulating sheet 1 and the tensile elastic modulus is usually 100 MPa · mm or more.
In addition, the tensile elasticity modulus in the sheet | seat 1 for electrical insulation is measured by the method similar to the method mentioned above.

The insulation life of the electrical insulation sheet 1 at an applied voltage of 25 kV / mm is preferably 200 seconds or more, and more preferably 300 seconds or more.
The insulation life of the electrical insulation sheet 1 at an applied voltage of 25 kV / mm is usually 2000 seconds or less.

  Next, a method for manufacturing the electrical insulating sheet 1 will be described.

The electrical insulating sheet 1 can be manufactured by a general method.
For example, the resin composition for molding the resin layer 2 can be prepared by mixing the above-described resin, inorganic filler, and if necessary, an additive while appropriately heating by a general method. Specifically, the resin composition can be prepared by, for example, mixing using a general mixing means such as a kneader, a pressure kneader, a kneading roll, a Banbury mixer, a twin screw extruder.
And the resin layer 2 is producible by extruding the resin composition prepared as mentioned above to a sheet form with the extruder which attached the T-die, for example. Or the resin layer 2 is producible by shape | molding a resin composition in a sheet form with an injection molding machine.
In this way, an electrical insulating sheet provided with only the resin layer 2 can be manufactured.

Moreover, the electrical insulating sheet 1 further provided with the adhesive layer 3 is prepared by, for example, applying an adhesive solution containing a solvent and an adhesive to one side of the resin layer 2 and volatilizing the solvent to produce the adhesive layer 3. Can be manufactured.
Or the sheet | seat 1 for electrical insulation further provided with the adhesion layer 3 can manufacture by employ | adopting a commercially available adhesive tape as the adhesion layer 3, and affixing a commercially available adhesive tape on the single side | surface side of the resin layer 2, for example. it can.

Since the electrical insulating sheet 1 has electrical insulation, it is used for electrical insulation. Specifically, the electrical insulation sheet 1 is used, for example, wound around a covering object.
The covering object is usually an electric conductor having a relatively low electric resistance. Examples of the conductor include metal plate-like bodies such as bus bars.
That is, the electrical insulation sheet 1 is used by being wound around a bus bar in a converter, an inverter, a transformer, or the like.

The sheet for electrical insulation of the present embodiment is as illustrated above, but the present invention is not limited to the sheet for electrical insulation illustrated above.
Moreover, the various aspects used in a general electrical insulation sheet can be employed within a range that does not impair the effects of the present invention.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

Using the raw materials shown below, a resin composition was prepared, and the resin composition was molded into a sheet shape to prepare a resin layer of an electrical insulating sheet.
・ Polysulfone resin:
Polyether polyphenylsulfone resin (PES) resin containing a plurality of sulfonyl groups and further containing a plurality of ether bonds and a plurality of aromatic hydrocarbons (product name “Ultrazone E2000” manufactured by BASF)
・ Polyamide resin:
Polyamide (PA) resin containing terephthalic acid units and nonanediamine units (PA9T Kuraray Co., Ltd., trade name “Genesta N1000A”)
・ Inorganic filler (Material: Magnesium hydroxide, Shape: Plate)
(Product name “MGZ-3” manufactured by Sakai Chemical Industry Co., Ltd.) Average particle size: 100 nm
Isoelectric point-12, endothermic decomposition start temperature -340 ° C
・ Inorganic filler (material: calcium carbonate, shape: rectangular parallelepiped)
(Product name “CALCIES” manufactured by Kamishima Chemical Co., Ltd.) Average particle size 60 nm
Isoelectric point -9, endothermic decomposition start temperature -600 ° C

-Adhesive tape Adhesive layer thickness 50 μm (Nitto Denko product name “No. 5915” Adhesive layer is composed of acrylic adhesive)

Example 1
Using a biaxial kneader (manufactured by Technobel), PES resin and PA resin were mixed (dry blended) at 300 ° C. so that the mass ratio of PES / PA = 80/20, and this resin mixture and hydroxylated Magnesium was further mixed at a mass ratio of resin mixture / magnesium hydroxide = 96/4 to prepare a resin composition.
Subsequently, the resin composition was molded into a sheet having a thickness of 100 μm at 300 ° C. by extrusion molding to produce a resin layer.
Thus, the sheet | seat (width 15cm x length 10m) provided only with the resin layer was manufactured.

(Example 2)
A sheet was produced in the same manner as in Example 1 except that the resin mixture and magnesium hydroxide were mixed so that the mass ratio of resin mixture / magnesium hydroxide = 94/6.

(Example 3)
Example 1 except that calcium carbonate is used in place of magnesium hydroxide as the inorganic filler, and the resin mixture and magnesium hydroxide are mixed so that the mass ratio of resin mixture / magnesium hydroxide = 94/6. A sheet was produced in the same manner as described above.

Example 4
A sheet (150 μm thick) provided with a resin layer and an adhesive layer was produced by applying the above-mentioned adhesive tape to one side of the resin layer produced in Example 1.

(Example 5)
A sheet (150 μm thick) provided with a resin layer and an adhesive layer was produced by applying the above-mentioned adhesive tape to one side of the resin layer produced in Example 2.

(Example 6)
A sheet (150 μm thick) provided with a resin layer and an adhesive layer was produced by applying the above-mentioned adhesive tape to one side of the resin layer produced in Example 3.

(Comparative Example 1)
Instead of the resin layer, a 210 μm-thick resin film (product name “NTN222” manufactured by Nitto Shinko Co., Ltd., a composite film of wholly aromatic polyamide paper and PET film) was prepared. The physical properties of such a film are as shown in Table 1.

(Comparative Example 2)
Instead of the resin layer, paper having a thickness of 185 μm (product name “NomexT410” wholly aromatic polyamide paper manufactured by DuPont) was prepared. The physical properties of such a film are as shown in Table 1.

(Comparative Example 3)
Instead of the resin layer, a resin film having a thickness of 125 μm (product name “Kapton” polyimide resin film manufactured by DuPont) was prepared. The physical properties of such a film are as shown in Table 1.

(Comparative Example 4)
Instead of the resin layer, a resin film having a thickness of 100 μm (product name “Teonex” polyethylene naphthalate resin film manufactured by Teijin DuPont) was prepared. The physical properties of such a film are as shown in Table 1.

(Comparative Examples 5-8)
Each sheet | seat was produced by affixing said adhesive tape on the single side | surface of the film or paper of Comparative Examples 1-4, respectively.

<Measurement of tensile modulus>
In accordance with JIS K7161, the tensile elastic modulus was measured at 23 ° C. under the tensile condition of 200 mm / min and the marked line of 50 mm.

<Measurement of electrical insulation life>
About the sheet | seat manufactured in each Example, and the film of each comparative example, the time to a dielectric breakdown was measured using the pressure | voltage resistant tester (The Tokyo Seimitsu company make, the high frequency pressure | voltage resistant tester "TSH-510").
Specifically, the frequency was 10 kHz, the applied voltage was 25 kV / mm, and a cylindrical electrode with a diameter of 25 mm was used as the electrode. The measurement temperature was 20 ° C.
After measuring 10 points on the measurement sample, a Weibull distribution of breakdown time was created, and the time when the cumulative occurrence probability was 63.2% was defined as the average insulation life time. And this average insulation life time was made into the electrical insulation life.

<Evaluation of winding follow-up (evaluation of deformability during winding)>
A test sample having a size of 25 mm (longitudinal direction) × 20 mm was cut from the film of each example sheet and each comparative example. This test sample was wound along the width direction of a hard copper plate (20 mm width × 1 mm thickness × 150 mm length).
Specifically, the test sample was wound so that the longitudinal direction of the test sample was along the width direction of the hard copper plate. More specifically, the test sample was wound by winding so as to cross in the width direction on one surface side of the hard copper plate and further folding back so that the length of 4 mm was in contact with the other surface side. A schematic diagram of the wound state is shown in FIG.
And according to the following reference | standard, the ease of bending of the folding | turning part of the sample for a test was confirmed visually.
○: The bent portion easily deforms following the shape of the hard copper plate. Δ: The bent portion deforms following the shape of the hard copper plate, but is difficult to bend. No (a gap is formed between the hard copper plate and the test sample at the bent part)

<Evaluation when observing the state after placing under high temperature after winding>
Each of the test samples was wound around a hard copper plate in the same manner as in the above “evaluation of winding follow-up”, and a load of 2 kg was applied in the thickness direction of the hard copper plate in the wound state. Thereafter, a test sample wound around a hard copper plate was allowed to stand at 120 ° C. for 24 hours so that the folded 4 mm long portion was on the upper side.
And according to the following reference | standard, the state in the 4 mm length part turned back was confirmed visually.
○: The folded portion is in contact with the hard copper plate. △: A portion of the folded portion is separated from the hard copper plate (a part is lifted).
×: The entire folded portion is separated from the hard copper plate

  Tables 1 and 2 show the thickness and tensile modulus of elasticity in each example and each comparative example, and the above evaluation results.

  As can be understood from the above results, the electrical insulating sheets of the examples have less reduction in electrical insulation, and can be sufficiently deformed following the winding around the electrical conductor, and can be wound. Even if it is later placed at a relatively high temperature, the wound state can be maintained.

  The electrical insulation sheet of the present invention can be suitably used as an electrical insulation sheet that requires electrical insulation, workability, and appropriate mechanical strength. Specifically, the electrical insulation sheet of the present invention is suitable for applications such as an electrical insulation member used by being wound around a bus bar in a converter or an inverter, for example.

1: Sheet for electrical insulation, 2: Resin layer, 3: Adhesive layer.

Claims (10)

  A resin layer containing a resin composition containing a resin and an inorganic filler is provided. The product of the thickness of the resin layer and the tensile modulus is 250 MPa · mm or less, and the applied voltage of the resin layer is 25 kV / An insulating sheet having an insulation life in mm of 200 seconds or longer.   The resin is at least one selected from the group consisting of a polysulfone resin, a polyarylene sulfide resin, a polyimide resin, and a polyamide resin, and the inorganic filler contains a metal hydroxide or a metal carbonate. The sheet for electrical insulation according to claim 1.   The sheet for electrical insulation according to claim 1 or 2, wherein the inorganic filler has an average particle size of 500 nm or less.   The electrical insulating sheet according to any one of claims 1 to 3, wherein the inorganic filler has an isoelectric point of 7 or more.   The sheet for electrical insulation according to any one of claims 2 to 4, wherein the metal hydroxide or the metal carbonate undergoes an endothermic decomposition reaction at a temperature exceeding 330 ° C.   The sheet-like adhesive layer which has adhesiveness rather than the said resin layer is further provided, and this adhesive layer is distribute | arranged to the at least single side | surface side of the said resin layer. Sheet.   The said adhesion layer contains at least 1 sort (s) selected from the group which consists of acrylic resin, rubber resin, silicone resin, polyester resin, polyurethane resin, and epoxy resin for electrical insulation of Claim 6. Sheet.   The sheet for electrical insulation according to claim 6 or 7, wherein the product of thickness and tensile elastic modulus is 350 MPa · mm or less, and the insulation life at an applied voltage of 25 kV / mm is 200 seconds or more.   The electrical insulation sheet according to any one of claims 1 to 8, which is used by being wound around a bus bar.   The sheet | seat for electrical insulation of any one of Claims 1-9 used by being wound around the bus bar in a converter or an inverter.

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