Insulating sheet

Abstract

The insulating sheet according to the present invention is provided with an adhesive layer and an insulating paper that is laminated on one surface of the adhesive layer and constitutes the outermost layer, the insulating paper being a wholly aromatic polyamide paper containing wholly aromatic polyamide fibers, the adhesive layer being composed of a resin composition, and the insulating paper being a wholly aromatic polyamide paper containing wholly aromatic polyamide fibers. The temperature at which 5 mass% weight loss is confirmed by thermogravimetric differential thermal analysis (TG-DTA) is 350 DEG C or less.

Description

[0001] Cross-references to related applications

[0002] This application claims the priority of Japanese Patent Application No. 2022-126149, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to an insulating sheet.

[0004] More specifically, the present invention relates to an insulating sheet for a motor used as an insulating sheet for a driving motor of an automobile. Background Art

[0005] Conventionally, a driving motor for an automobile includes a rotor and a stator that generates a force for rotating the rotor.

[0006] The stator includes a plurality of coils, and a Lorentz force is obtained by generating a magnetic field in the plurality of coils, and the rotor is rotated by the Lorentz force.

[0007] In the drive motor as described above, the coil is composed of, for example, a plurality of segmented conductors connected to each other, and is usually used by being attached to a member in which magnetic steel plates are stacked, which is called a stator core or a rotor core.

[0008] In the drive motor as described above, the core such as the stator core and the rotor core has a plurality of slots, and the coils are respectively accommodated in the plurality of slots.

[0009] In the drive motor as described above, an insulating sheet for ensuring insulation between the coil and the inner wall surface of the slot is housed in each slot together with the coil. More specifically, the insulating sheet is housed in the slot in a state of surrounding the coil.

[0010] Furthermore, the coil surrounded by the insulating sheet is fixed in the slot by an insulating resin (eg epoxy varnish) impregnated into the slot.

[0011] For example, as described in the following patent document 1, the insulating sheet has a five-layer structure, which includes: a polyester resin layer composed of a polyester film, two paper-like sheet layers respectively arranged on the upper side and the lower side of the polyester resin layer, and two adhesive layers respectively arranged between the polyester resin layer and the paper-like sheet.

[0012] That is, the insulating sheet has a five-layer structure in which the paper-like sheet layer is arranged as a surface layer and the polyester resin layer is arranged as an inner layer.

[0013] As described in Patent Document 1 listed below, the paper-like sheet layer is composed of a paper-like sheet, and as the paper-like sheet, for example, so-called "aramid paper" containing wholly aromatic polyamide fibers as a main material is used.

[0014] Furthermore, the adhesive layer is usually formed of an adhesive containing a polyurethane resin or the like as a main component.

[0015] Prior art literature

[0016] Patent Literature

[0017] Patent Document 1: Japanese Patent Application Publication No. 2016-54629 Summary of the invention

[0018] Problem that the invention aims to solve

[0019] In recent years, there has been a growing demand for higher output of driving motors for automobiles.

[0020] Furthermore, as the output of the driving motor of the automobile increases, the insulating sheet used in the driving motor is required to have properties such as high heat resistance and high withstand voltage.

[0021] A wholly aromatic polyamide paper such as aramid paper has the property of being excellent in heat resistance, and a polyester film has the properties of being excellent in heat resistance and voltage resistance.

[0022] Therefore, as described in Patent Document 1, an insulating sheet having a wholly aromatic polyamide paper arranged on the surface layer and a polyester layer composed of a polyester film arranged on the inner layer can meet the demand for higher output.

[0023] However, in the drive motor described above, when the insulating sheet described in Patent Document 1 is used to ensure insulation between the coil and the inner wall surface of the slot, the inner wall surface of the slot reaches a high temperature when the drive motor is driven.

[0024] As described above, since the wholly aromatic polyamide paper has excellent heat resistance, even when the inner wall surface of the slot reaches a high temperature, the organic matter contained in the wholly aromatic polyamide paper is difficult to be thermally decomposed on the outer surface of the wholly aromatic polyamide paper (the surface in contact with the inner wall surface of the slot).

[0025] Therefore, the decomposed products of the organic matter are not gasified but remain on the outer surface of the wholly aromatic polyamide paper in the form of free carbon, and a conductive path caused by the free carbon is formed on the outer surface of the wholly aromatic polyamide paper.

[0026] That is, tracking may occur on the outer surface of the wholly aromatic polyamide paper.

[0027] Furthermore, even if the conductive path formed on the outer surface of the wholly aromatic polyamide paper is minute, if the output of the drive motor is further increased, tracking will be significantly generated on the outer surface of the wholly aromatic polyamide paper.

[0028] As described above, when the tracking occurs as the output of the drive motor increases, the tracking resistance of the insulating sheet deteriorates, which is not preferable.

[0029] As described above, the tracking resistance of the insulating sheet may be deteriorated even when the insulating sheet is used for purposes other than the driving motor.

[0030] However, it cannot be said that sufficient research has been conducted on suppressing the deterioration of the tracking resistance of the insulating sheet.

[0031] Therefore, an object of the present invention is to provide an insulating sheet capable of exhibiting sufficient anti-tracking properties even when wholly aromatic polyamide paper containing wholly aromatic polyamide fibers is used as insulating paper.

[0032] Solutions for solving problems

[0033] The insulating sheet of the present invention comprises an adhesive layer and insulating paper.

[0034] The insulating paper is stacked on one surface of the adhesive layer and constitutes the outermost layer.

[0035] The insulating paper is a wholly aromatic polyamide paper containing wholly aromatic polyamide fibers.

[0036] The adhesive layer is composed of a resin composition, and the temperature at which 5% weight loss is confirmed in thermogravimetric differential thermal analysis (TG-DTA) is 350° C. or less. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a cross-sectional view showing the structure of an insulating sheet according to one embodiment of the present invention.

[0038] Figure 2 This is a schematic perspective view of a stator of a driving motor of an automobile.

[0039] Figure 3 is a schematic top view of the stator core.

[0040] Figure 4 yes Figure 3 Enlarged view of part A. DETAILED DESCRIPTION

[0041] Hereinafter, one embodiment of the present invention will be described.

[0042] It should be noted that, hereinafter, one embodiment of the present invention is simply referred to as this embodiment.

[0043] The insulating sheet according to the present embodiment includes an adhesive layer and insulating paper, and the insulating paper is laminated on one surface of the adhesive layer and constitutes the outermost layer.

[0044] In the insulating sheet according to the present embodiment, the insulating paper is wholly aromatic polyamide paper containing wholly aromatic polyamide fibers.

[0045] In the insulating sheet according to the present embodiment, the adhesive layer is made of a resin composition, and the temperature at which 5% weight loss is confirmed in thermogravimetric differential thermal analysis (TG-DTA) is 350° C. or less.

[0046] The resin composition may contain an organic solvent (eg, methyl ethyl ketone (MEK)) for suspending or dissolving the resin.

[0047] That is, the resin composition may be a resin solution containing the organic solvent.

[0048] The following are listed Figure 1 The insulating sheet according to this embodiment will be described by taking the insulating sheet having a five-layer structure as shown as an example.

[0049] (Insulation Sheet)

[0050] like Figure 1 As shown, the insulating sheet 10 according to the present embodiment is formed by laminating first insulating paper 3a and second insulating paper 3b on both surfaces of a base film 1a via first adhesive layer 2a and second adhesive layer 2b, respectively.

[0051] That is, the insulating sheet 10 according to the present embodiment has a five-layer structure in which the first insulating paper 3a, the first adhesive layer 2a, the base film 1a, the second adhesive layer 2b, and the second insulating paper 3b are stacked in this order.

[0052] In the insulating sheet 10 according to the present embodiment, the first insulating paper 3a and the second insulating paper 3b constitute the outermost layer.

[0053] The insulating sheet 10 according to the present embodiment is used as an insulating sheet for a driving motor of an automobile, for example.

[0054] As the driving motor of the above-mentioned automobile, an oil-cooled driving motor can be cited.

[0055] It should be noted that the oil-cooled drive motor is a drive motor that is cooled by cooling oil such as ATF.

[0056] Examples of the automobile include a hybrid electric vehicle (HEV) and an electric vehicle (EV).

[0057] Examples of the drive motor include an HV motor, a motor generator, an AC generator, a 4WD motor, an oil pump motor, an EPS motor, a compressor motor, and a hub motor.

[0058] In the insulating sheet 10 according to the present embodiment, the first insulating paper 3a and the second insulating paper 3b are wholly aromatic polyamide papers containing wholly aromatic polyamide fibers.

[0059] The wholly aromatic polyamide paper has excellent heat resistance. Therefore, by using the wholly aromatic polyamide paper for the first insulating paper 3 a and the second insulating paper 3 b , the insulating sheet 10 according to the present embodiment can exhibit excellent heat resistance.

[0060] The wholly aromatic polyamide paper is preferably produced by a wet papermaking method using wholly aromatic polyamide fibers.

[0061] Examples of the wholly aromatic polyamide paper include paper mainly composed of wholly aromatic polyamide fibers obtained by fibrillating a polycondensate (wholly aromatic polyamide) of phenylenediamine and phthalic acid, the remainder of which is composed of benzene rings except for amide groups, and fibrillating the fiber.

[0062] As the wholly aromatic polyamide paper, for example, paper marketed by Dupont under the trade name of "Nomex (registered trademark)" can be used.

[0063] The wholly aromatic polyamide paper may or may not be surface-coated with a coating agent.

[0064] Examples of the coating agent include coating agents containing polyamide resins.

[0065] As the polyamide resin, a methoxymethylated polyamide resin in which at least a part of the amide group is methoxymethylated is preferably used.

[0066] The thickness of the first insulating paper 3 a and the second insulating paper 3 b may be 20 μm or more, 25 μm or more, or 30 μm or more.

[0067] In addition, the thickness of the first insulating paper 3a and the second insulating paper may be 250 μm or less, 10 μm or less, or 70 μm or less.

[0068] As described above, in the insulating sheet 10 according to the present embodiment, since wholly aromatic polyamide paper is used as the first insulating paper 3a and the second insulating paper 3b, the insulating sheet 10 can be endowed with high mechanical properties by setting the thickness of the first insulating paper 3a and the second insulating paper 3b to the above-mentioned numerical range.

[0069] Furthermore, by setting the thickness of the first insulating paper 3 a and the second insulating paper 3 b to be within the above-mentioned numerical range, it is possible to achieve excellent shape retainability of the insulating sheet 10 subjected to the bending process.

[0070] Furthermore, the thicknesses of the first insulating paper 3a and the second insulating paper 3b may be the same or different from each other.

[0071] The thickness of the first insulating paper 3a and the second insulating paper 3b can be determined by measuring the thickness of 10 randomly selected locations using a digital micrometer and taking the arithmetic average of the measured values.

[0072] In the insulating sheet 10 according to this embodiment, the first adhesive layer 2a can be formed by, for example, applying a resin composition on one surface of the base film 1a, and the second adhesive layer 2b can be formed by applying a resin composition on the other surface of the base film 1a.

[0073] In addition, the first adhesive layer 2a can also be formed by applying a resin composition on one surface of the first insulating paper 3a (the surface opposite to the substrate film 1a), and the second adhesive layer 2b can also be formed by applying a resin composition on one surface of the second insulating paper 3b (the surface opposite to the substrate film 1a).

[0074] The coating amount of the resin composition is preferably 10 g / m 2 Above and 20g / m 2 the following.

[0075] By setting the coating amount to 10 g / m 2 As described above, the first adhesive layer 2a and the second adhesive layer 2b have sufficient bonding strength.

[0076] In addition, by setting the coating amount to 20 g / m 2 Thereby, the first adhesive layer 2a and the second adhesive layer 2b can be formed thinly.

[0077] As described above, by forming the first adhesive layer 2 a and the second adhesive layer 2 b thinly, the thickness of the insulating sheet 10 according to the present embodiment can be reduced.

[0078] As a result, the insulating sheet 10 according to the present embodiment can be easily inserted into a narrow location.

[0079] The first adhesive layer 2a and the second adhesive layer 2b may have the same thickness or different thicknesses, but preferably have the same thickness.

[0080] The resin composition preferably contains, as the resin, an acrylic resin, a polyurethane resin, an epoxy resin, an epoxy ester resin, a polyester resin, a silicone resin or the like.

[0081] In the resin composition, as the resin, it is more preferred that the resin be contained in the acrylic resin, the polyurethane resin, or the epoxy resin, and it is particularly preferred that the resin be contained in the acrylic resin.

[0082] As the acrylic resin, for example, a homopolymer of a monomer represented by the following formula (1) or a copolymer having a structural unit based on the monomer can be used.

[0083] CH2=C(R 1 )-COOR 2 …(1)

[0084] Among them, R 1 is a hydrogen atom or a lower alkyl group, R 2 It is an alkyl group having 1 to 12 carbon atoms.

[0085] Specifically, one or more of polyacrylates such as polymethyl acrylate, polyethyl acrylate, and polybutyl acrylate (PAB); polymethacrylates such as polymethyl methacrylate, polyethyl methacrylate, and polybutyl methacrylate; and copolymers such as ethylene-acrylate copolymers, ethylene-acrylate-acrylic acid copolymers, styrene-methacrylate-acrylic acid copolymers, acrylate-vinyl chloride copolymers, acrylate-acrylic acid copolymers, methacrylate-vinyl chloride copolymers, styrene-methacrylate-butadiene copolymers, and methacrylate-acrylonitrile copolymers can be used.

[0086] Among these, polybutyl acrylate (PAB) is preferably used as the acrylic resin.

[0087] When the resin composition contains the polybutyl acrylate as the acrylic resin, the resin composition preferably contains a polyisocyanate in addition to the polybutyl acrylate.

[0088] Furthermore, as described above, in the resin composition containing the polybutyl acrylate and the polyisocyanate, the polybutyl acrylate is preferably cross-linked by the polyisocyanate.

[0089] Furthermore, in the above case, the resin composition preferably contains 3 parts by mass or more of the polyisocyanate, more preferably 10 parts by mass or more, based on 100 parts by mass of the polybutyl acrylate.

[0090] The resin composition preferably contains 25 parts by mass or less, and more preferably 20 parts by mass or less, of the polyisocyanate based on 100 parts by mass of the polybutyl acrylate.

[0091] In addition, polybutyl acrylate (PAB) may have a carboxyl group.

[0092] Furthermore, when the resin composition contains the polybutyl acrylate and the polyisocyanate, the resin composition preferably further contains terpene phenol.

[0093] In the resin composition, the polyacrylic acid and the terpene phenol are preferably cross-linked with the polyisocyanate.

[0094] In the above case, the resin composition preferably contains 1 part by mass or more and 30 parts by mass or less of the terpene phenol based on 100 parts by mass of the polybutyl acrylate.

[0095] Furthermore, the resin composition may contain an alkylphenol instead of the terpene phenol.

[0096] In the above case, the resin composition preferably contains 1 part by mass or more and 30 parts by mass or less of the alkylphenol based on 100 parts by mass of the polybutyl acrylate.

[0097] The polyurethane resin is obtained by urethane bonding reaction components including a polyol component having two or more hydroxyl groups in one molecule and a polyisocyanate component having two or more isocyanate groups in one molecule.

[0098] It should be noted that, in the present specification, the “polyurethane resin” does not refer to a “polyurethane resin” in a broad sense including a “polyurethane-urea resin”, but refers to a “polyurethane resin” that does not substantially contain a urea bond.

[0099] As the polyol component, a conventionally known polyol component used in synthesizing a polyurethane resin can be used.

[0100] Specific examples of the polyol component include polyester polyol, polyether polyol, polycarbonate polyol, and other polyols.

[0101] Specific examples of the polyester polyols include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene adipate / butylene adipate diol, polyneopentyl adipate / hexyl adipate diol, poly-3-methylpentane adipate diol, polybutylene isophthalate diol, polycaprolactone diol, poly-3-methylvalerolactone diol, and the like.

[0102] The aforementioned polyester polyol has a property of being excellent in heat resistance.

[0103] Therefore, when the resin composition includes the polyurethane resin and the polyol component of the polyurethane resin is the polyester polyol, the adhesive layer formed from the resin composition has excellent heat resistance.

[0104] Specific examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and random / block copolymers thereof.

[0105] The aforementioned polyether polyol has excellent hydrolysis resistance.

[0106] Therefore, when the resin composition contains the polyurethane resin and the polyol component of the polyurethane resin is the polyether polyol, the adhesive layer formed from the resin composition has excellent hydrolysis resistance.

[0107] Specific examples of the polycarbonate polyol include polytetramethylene carbonate diol, polypentamethylene carbonate diol, polyneopentyl carbonate diol, polyhexamethylene carbonate diol, poly(1,4-cyclohexanedimethylene carbonate) diol, and random / block copolymers thereof.

[0108] The polycarbonate polyol has properties of being excellent in heat resistance and hydrolysis resistance.

[0109] Therefore, when the resin composition contains the polyurethane resin and the polyol component of the polyurethane resin is the polycarbonate polyol, the adhesive layer formed from the resin composition has excellent heat resistance and excellent hydrolysis resistance.

[0110] Specific examples of the aforementioned other polyols include dimer diol or its hydride, polybutadiene polyol or its hydride, polyisoprene polyol or its hydride, acrylic polyol, epoxy polyol, polyether ester polyol, silicone-modified polyol, α,ω-polymethyl methacrylate diol, α,ω-polybutyl methacrylate diol, etc.

[0111] Among these, the hydrogenated product of dimer diol and the hydrogenated product of polybutadiene polyol have excellent properties of heat resistance and hydrolysis resistance, similar to the above-mentioned polycarbonate polyol.

[0112] Therefore, when the resin composition includes the polyurethane resin and the polyol component of the polyurethane resin is a hydrogenated product of the dimer diol or a hydrogenated product of the polybutadiene polyol, the adhesive layer formed from the resin composition has excellent heat resistance and hydrolysis resistance.

[0113] As the resin composition containing the polyurethane resin, that is, the urethane resin composition, a product name "TYFORCE SA-30-L" manufactured by DIC Corporation or the like can be used.

[0114] Note that "TYFORCE SA-30-L" is obtained by suspending a polyurethane resin at a predetermined concentration (15 to 25 mass%) in a mixed organic solvent of toluene (TOL) and methyl ethyl ketone (MEK) (toluene (TOL): 40 to 50 vol%, methyl ethyl ketone (MEK): 30 to 40 vol%).

[0115] As the polyisocyanate component, a conventionally known polyisocyanate component used for producing a polyurethane resin can be used.

[0116] Specific examples of the polyisocyanate component include toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 4,4'-methylenebis(phenylene isocyanate) (MDI), crude MDI or polymerized MDI, d-isocyanate, xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate, 4,4'-methylenebis(phenylene isocyanate) (MDI), and 1,5-naphthalene diisocyanate. Aromatic diisocyanates such as isocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate, and 4,4'-dibenzyl diisocyanate; aliphatic diisocyanates such as methylene diisocyanate and 1,4-tetramethylene diisocyanate; alicyclic isocyanates such as 1,4-cyclohexylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, and hydrogenated XDI; polyurethane prepolymers obtained by reacting these diisocyanates with low molecular weight polyols in a manner that the ends become isocyanates, etc.

[0117] It should be noted that the polyurethane resin can be produced by a conventionally known method for producing polyurethane.

[0118] For example, the polyurethane resin can be produced by reacting the polyol component and the polyisocyanate component by a one-step method or a multi-step method.

[0119] The one-step method and the multi-step method can be carried out usually at a temperature in the range of 20°C to 150°C, preferably 60°C to 110°C.

[0120] As the aforementioned epoxy resin, various known epoxy resins can be used, such as phenol novolac type epoxy resin, triphenylmethane type epoxy resin, cresol novolac type epoxy resin, bisphenol A type epoxy resin, modified bisphenol A type epoxy resin, bisphenol F type epoxy resin, modified bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, modified bisphenol AD ​​type epoxy resin, dicyclopentadiene type epoxy resin, biphenyl type epoxy resin, etc.

[0121] Among these, it is preferable to use the phenol novolac type epoxy resin as the epoxy resin.

[0122] The epoxy equivalent of the phenol novolac epoxy resin is preferably 150 g / eq or more, more preferably 160 g / eq or more, and even more preferably 170 g / eq or more.

[0123] The epoxy equivalent is preferably 200 g / eq or less, more preferably 190 g / eq or less, and even more preferably 180 g / eq or less.

[0124] The epoxy equivalent can be determined according to JIS K 7236.

[0125] When the resin composition includes the epoxy resin, the resin composition preferably further includes a curing agent for the epoxy resin.

[0126] Examples of the curing agent for the epoxy resin include phenolic curing agents, amine curing agents, and acid anhydride curing agents.

[0127] The phenol-based curing agent, the amine-based curing agent, and the acid anhydride-based curing agent may be used alone or in combination of two or more.

[0128] Among these, the above-mentioned phenol-based curing agents are preferably used.

[0129] Examples of the phenolic curing agent include phenol novolac resins, aralkyl phenolic resins, dicyclopentadiene-modified phenolic resins, naphthalene phenolic resins, bisphenol phenolic resins, and triphenylmethane phenolic resins.

[0130] Examples of the amine-based curing agent include diaminodiphenyl sulfone, dicyandiamide, diaminophenylmethane, and triethylenetetramine.

[0131] Examples of the acid anhydride curing agent include phthalic anhydride, trimellitic anhydride, and maleic anhydride.

[0132] In the above case, the resin composition may contain 10 parts by mass or more of the epoxy resin curing agent, 20 parts by mass or more, 30 parts by mass or more, or 40 parts by mass or more, based on 100 parts by mass of the epoxy resin.

[0133] Furthermore, in the above case, the resin composition may contain 70 parts by mass or less, 60 parts by mass or less, or 50 parts by mass or less of the epoxy resin curing agent based on 100 parts by mass of the epoxy resin.

[0134] In the above case, the resin composition may further contain a curing accelerator in addition to the curing agent for the epoxy resin.

[0135] Examples of the curing accelerator include tetraphenylphosphonium tetraphenylborate, imidazoles, triphenyl phosphate (TPP), and amine-based curing accelerators.

[0136] Examples of the amine-based curing accelerator include boron trifluoride monoethylamine and the like.

[0137] In the above case, the resin composition may contain 0.1 parts by mass or more, 0.5 parts by mass or more, 1 part by mass or more, or 2 parts by mass or more of the curing accelerator based on 100 parts by mass of the epoxy resin.

[0138] Furthermore, in the above case, the resin composition may contain 10 parts by mass or less, 7 parts by mass or less, or 4 parts by mass or less of the curing accelerator based on 100 parts by mass of the epoxy resin.

[0139] When the resin composition includes the epoxy resin, the resin composition may further include the acrylic resin in addition to the epoxy resin.

[0140] Furthermore, in the resin composition, in addition to the phenol novolac epoxy resin as the epoxy resin, it is preferred that the resin composition further comprises the polybutyl acrylate (PAB) as the acrylic resin.

[0141] In the above case, the resin composition may contain 100 parts by mass or more, 150 parts by mass or more, or 200 parts by mass or more of the acrylic resin based on 100 parts by mass of the epoxy resin.

[0142] The resin composition may contain 300 parts by mass or less, or 250 parts by mass or less, of the acrylic resin relative to 100 parts by mass of the epoxy resin.

[0143] As described above, in the insulating sheet 10 according to the present embodiment, the temperature at which the first adhesive layer 2a and the second adhesive layer 2b lose 5% by mass in thermogravimetric differential thermal analysis (TG-DTA) is 350°C or less.

[0144] Therefore, when the insulating sheet 10 according to the present embodiment is exposed to a high temperature atmosphere, in the first adhesive layer 2 a and the second adhesive layer 2 b , organic substances such as resins contained in these adhesive layers are easily thermally decomposed.

[0145] In addition, the temperature at which 5% by mass weight loss is confirmed can be determined by the method described in the examples.

[0146] The insulating sheet 10 according to the present embodiment is used, for example, in a driving motor including a rotor, a stator having a plurality of slots, and a plurality of coils accommodated in the plurality of slots to ensure insulation between the stator and the plurality of coils.

[0147] Specifically, the insulating sheet 10 according to the present embodiment is housed in the plurality of slots in a state of surrounding each of the plurality of coils, thereby ensuring insulation between the stator and the plurality of coils.

[0148] Furthermore, when the driving motor is driven, the inner surface of each of the plurality of slots reaches a high temperature.

[0149] Here, as described above, in the insulating sheet 10 according to the present embodiment, in the first adhesive layer 2 a and the second adhesive layer 2 b , organic substances such as resins contained in these adhesive layers are easily thermally decomposed.

[0150] Therefore, on the outer surface of the insulating paper (either the first insulating paper 3a or the second insulating paper 3b) that contacts the inner surfaces of each of the aforementioned multiple slots, before the organic matter contained in the insulating paper is thermally decomposed, the organic matter contained in these adhesive layers is thermally decomposed in the first adhesive layer 2a and the second adhesive layer 2b.

[0151] In this way, since the heat generated by the high temperature of the inner surfaces of the plurality of slots causes the organic matter contained in the first adhesive layer 2a and the second adhesive layer 2b to be thermally decomposed and consumed, thermal decomposition of the organic matter contained in the insulating paper is suppressed on the outer surface of the insulating paper.

[0152] Furthermore, to the extent that thermal decomposition of organic matter contained in the insulating paper is suppressed, formation of a conductive path due to free carbon on the outer surface of the insulating paper is suppressed.

[0153] Furthermore, depending on the degree to which the organic matter contained in the first adhesive layer 2a and the second adhesive layer 2b is easily thermally decomposed, the organic matter does not remain in the state of free carbon but is fully thermally decomposed into gas such as carbon dioxide.

[0154] Furthermore, since the reaction for generating gas as described above is an endothermic reaction, the endothermic reaction also takes away the heat generated on the inner surface of each of the plurality of slots.

[0155] As a result, thermal decomposition of organic matter contained in the insulating paper is also suppressed on the outer surface of the insulating paper, and thus formation of a conductive path due to free carbon on the outer surface can be further suppressed.

[0156] In summary, in the insulating sheet 10 according to the present embodiment, although the first insulating paper 3a and the second insulating paper 3b constituting the outermost layer are wholly aromatic polyamide papers, they can still exhibit sufficient tracking resistance.

[0157] The thickness of the first adhesive layer 2a and the second adhesive layer 2b is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 20 μm or more.

[0158] In addition, the thickness of the first adhesive layer 2a and the second adhesive layer 2b is preferably 40 μm or less.

[0159] The thickness of the first adhesive layer 2 a and the second adhesive layer 2 b can be measured using a digital microscope (for example, model: VHX-8000 manufactured by KEYENCE Corporation).

[0160] Specifically, it can be measured as follows.

[0161] (1) One side surface of the insulating sheet 10 is photographed using the camera provided in the digital microscope to obtain an image.

[0162] (2) Displaying the image on a display provided in the digital microscope.

[0163] (3) In the image displayed on the display, the thicknesses of the first adhesive layer 2a and the second adhesive layer 2b are calculated at 10 randomly selected locations, and the calculated thicknesses of the first adhesive layer 2a and the second adhesive layer 2b are arithmetic averaged.

[0164] In the insulating sheet 10 according to the present embodiment, the thickness of the insulating paper (the total value of the thickness of the first insulating paper 3a and the thickness of the second insulating paper 3b) is denoted as T. IP , the thickness of the adhesive layer (the total value of the thickness of the first adhesive layer 2a and the thickness of the second adhesive layer 2b) is set to T AL When the thickness T AL Relative to thickness T IP The ratio is preferably 40% or more.

[0165] Thickness T AL Relative to thickness T IP The fact that the ratio of is within the above numerical range means that in the insulating sheet 10 according to the present embodiment, the first adhesive layer 2a and the second adhesive layer 2b have sufficient thickness.

[0166] Furthermore, the fact that the first adhesive layer 2 a and the second adhesive layer 2 b have sufficient thickness means that organic substances that are easily thermally decomposed are present more sufficiently in the insulating sheet 10 according to the present embodiment.

[0167] Therefore, if the thickness T AL Relative to thickness T IP When the ratio is within the above numerical range, the thermal decomposition of the organic matter contained in the first adhesive layer 2a and the second adhesive layer 2b can be more fully performed.

[0168] As a result, on the outer surfaces of the first insulating paper 3a and the second insulating paper 3b, thermal decomposition of organic matter contained in these insulating papers can be further suppressed, and thus formation of conductive paths due to free carbon on the outer surfaces of these insulating papers can be further suppressed.

[0169] In summary, the insulating sheet 10 described in this embodiment can exert more sufficient tracking resistance.

[0170] In addition, in the insulating sheet 10 according to the present embodiment, the thickness T AL Relative to thickness T IP The ratio is more preferably 45% or more, more preferably 50% or more, more preferably 55% or more, and more preferably 60% or more.

[0171] By making the thickness T AL Relative to thickness T IPWhen the ratio is within the above numerical range, the insulating sheet 10 according to the present embodiment can exhibit more sufficient anti-tracking performance.

[0172] It should be noted that the thickness T AL Relative to thickness T IP The ratio may be 80% or less, or 70% or less.

[0173] Furthermore, in the insulating sheet 10 according to the present embodiment, the thickness (total thickness) of the insulating sheet 10 is T T When the thickness T AL Relative to thickness T T The ratio is preferably 21% or more, more preferably 22% or more, and further preferably 23% or more.

[0174] By making the thickness T AL Relative to thickness T T When the ratio is within the above numerical range, the insulating sheet 10 according to the present embodiment can exhibit more sufficient anti-tracking performance.

[0175] It should be noted that the thickness T AL Relative to thickness T T The ratio may be 30% or less, 28% or less, or 26% or less.

[0176] The first adhesive layer 2a and the second adhesive layer 2b may contain various known additives.

[0177] Examples of the additives include thickeners, dispersants, antioxidants, antioxidants, processing aids, stabilizers, defoamers, flame retardants, thickeners, pigments, and the like.

[0178] In the insulating sheet 10 according to the first embodiment, the base film 1 a is preferably a polyester film made of a polyester resin.

[0179] Examples of the polyester resin include polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, polybutylene naphthalate (PBN) resin, and polyethylene naphthalate (PEN) resin.

[0180] Among these, the polyester resin constituting the polyester film is preferably either polyethylene terephthalate (PET) resin or polyethylene naphthalate (PEN) resin.

[0181] That is, the polyester film is preferably any of a polyethylene terephthalate (PET) film and a polyethylene naphthalate (PEN) film.

[0182] Alternatively, the base film 1 a may be a polyimide (PI) film made of a polyimide (PI) resin.

[0183] When the base film 1a is a PET film or a PEN film, the film may be composed of a low-oligomer product having an oligomer content of 1% by mass or less.

[0184] Since the film is composed of a low oligomer product, the base film 1a has excellent hydrolysis resistance.

[0185] The oligomer content can be determined, for example, as follows.

[0186] (1) A roughly square film sample with a side length of about 5 cm was washed with methanol and then dried in a hot air oven at 160° C. for 1 hour to determine the initial mass (M1 (g)).

[0187] (2) The film sample is subjected to extraction treatment in boiling xylene (about 400 mL) for 48 hours using a Soxhlet extractor or the like.

[0188] (3) The mass of the film sample after the extraction treatment (M2 (g)) was measured, and the ratio of the weight loss (M1-M2) to the initial mass (M1) was calculated ((M1-M2) / M1).

[0189] Here, regarding the mass (M2 (g)) of the film sample after the extraction treatment, the weight loss cannot be accurately determined unless the xylene used in the extraction treatment is fully removed from the film sample before measurement.

[0190] Therefore, it is preferred that after the xylene extraction, the film sample is washed with water, the xylene adhering to the surface is gently wiped off, and then it is dried in a hot air oven at 160° C. for 8 hours and naturally cooled in a dryer before measurement.

[0191] The thickness of the base film 1 a is preferably 10 μm or more, more preferably 15 μm or more, and further preferably 25 μm or more.

[0192] The thickness of the base film 1 a is preferably 250 μm or less, more preferably 100 μm or less, and even more preferably 75 μm or less.

[0193] The thickness of the base film 1 a can also be measured in the same manner as the thickness of the first insulating paper 3 a and the second insulating paper 3 b .

[0194] The insulating sheet 10 according to this embodiment preferably has a 1×10 13 The volume resistivity is greater than Ω·cm, and more preferably 1×10 14 Volume resistivity above Ω·cm.

[0195] By having the above-described volume resistivity, the insulating sheet 10 according to the present embodiment can exhibit excellent electrical insulation properties.

[0196] As described above, the insulating sheet 10 according to the present embodiment can be used for a driving motor of an automobile.

[0197] Therefore, the following refers to Figures 2 to 4 Next, an example in which the insulating sheet 10 according to the present embodiment is used in a driving motor of an automobile will be described.

[0198] The drive motor includes a rotor having a permanent magnet and a stator having a coil, and includes the coil formed of a segment conductor.

[0199] Furthermore, the insulating sheet 10 according to the present embodiment is used for insulation between the coil and the core in the stator.

[0200] Figure 2 This is a perspective view of a stator 1 of a drive motor. As shown in the figure, the stator 1 has a stator core 20 and a coil 30 .

[0201] Figure 3 FIG. 1 is a top view of the stator 1 as viewed from the direction of the rotation axis (arrow AD) of the rotor (not shown). Figure 4 To express in Figure 3 The illustrated section A of the stator core 20 is a cross-sectional view showing a state where a plurality of coils 30 are housed.

[0202] As shown in these drawings, in the stator 1 , a plurality of slots 21 are formed on the inner peripheral surface side of a cylindrical stator core 20 .

[0203] The stator 1 has a stator core 20 and a plurality of coils 30 accommodated in a plurality of slots 21 formed in the stator core 20 .

[0204] The plurality of slots 21 are arranged such that each slot 21 is arranged along the rotation axis direction of the stator core 20 ( Figure 3 AD) extends in the circumferential direction of the stator core 20 ( Figure 2 The two components are arranged on the stator core 20 in a state where a predetermined interval is maintained between each other on RD).

[0205] The slot 21 is formed over the entire length of the stator core 20 in the rotation axis direction AD, and is formed on one end surface 20a ( Figure 3 An opening portion 21 b having the same shape as the cross-sectional shape of the slot 21 is formed on the upper side of the slot 21 (hereinafter also referred to as the “upper end face 20 a ”) and the other end face 20 b (hereinafter also referred to as the “lower end face 20 b ”).

[0206] In the stator core 20 , as described above, the plurality of slots 21 are parallel to each other, and therefore, the plate-like protrusions 22 are formed between the slots 21 adjacent to each other.

[0207] In the radial direction ( Figure 2 A plurality of plate-like protrusions 22 (hereinafter also referred to as “teeth 22”) are formed in a state of protruding inside (in the DD direction).

[0208] It should be noted that if Figure 3 and Figure 4 As shown, the tooth 22 has a wide portion 22 a that is widened along the circumferential direction RD of the stator core 20 at the front end portion in the protruding direction, and has a T-shaped cross-sectional shape.

[0209] Therefore, the width of the slot 21 is narrowed on the inner peripheral surface side of the stator core 20, and only a small linear opening 21a is formed.

[0210] The coil 30 is composed of a plurality of segmented conductors 31 connected to each other.

[0211] It should be noted that if Figure 2 As shown, the split conductor 31 before forming the coil is a rectangular enameled wire bent into a U-shape, and includes two leg portions 31 b and a head portion 31 a connecting the two leg portions 31 b.

[0212] The split conductor 31 has a copper wire exposed portion from which the insulation coating is peeled off at a front end portion 31 bx of the leg portion 31 b on the opposite side to the head portion 31 a .

[0213] The coil 30 is manufactured as follows: the leg 31b of the split conductor 31 is inserted from the opening 21b of the narrow slot 21 in the upper end surface 20a of the stator core 20, and the front end 31bx is exposed from the lower end surface 20b of the stator core 20, and then the leg 31b of one split conductor 31 is electrically connected to the leg 31b of another split conductor 31 at the copper wire exposed portion to form a connecting portion 31x, and then the connecting portion 31x is insulated to manufacture.

[0214] It should be noted that the two leg portions 31 b of one split conductor 31 are respectively inserted into different slots 21 .

[0215] The coil 30 is manufactured as described above, so the stator 1 has an upper coil tail end portion formed by the head 31a of the split conductor 31 on the upper end surface 20a side of the stator core 20, and has a lower coil tail end portion formed by the connecting portion 31x on the lower end surface 20b side, and the connecting portion 31x is formed by connecting the legs 31b to each other.

[0216] like Figure 4As shown, four legs 31 b of the split conductors 31 forming the coils 30 are respectively accommodated in the narrow slots 21 of the stator core 20 (one leg 31 b of four split conductors 31 is respectively accommodated), and a total of four legs 31 b are accommodated in each narrow slot 21 in a state of being arranged in a row from the inner peripheral surface side to the outer peripheral surface side.

[0217] like Figure 4 As shown, the insulating sheet 10 according to the present embodiment is inserted between the four leg portions 31 b and the inner wall surface of the slot 21 .

[0218] The insulating sheet 10 described in this embodiment is longitudinally attached along the length direction of the leg portion 31b of the split conductor 31, and is arranged in the narrow slot 21 in the form of surrounding the four leg portions 31b more than one circle, and is arranged in the narrow slot 21 so that the two end portions in the rotation axis direction AD protrude from the upper end surface 20a and the lower end surface 20b of the stator core 20 to the outside of the rotation axis direction AD.

[0219] As described above, the insulating sheet 10 according to the present embodiment is arranged in the slit 21 so as to surround the four leg portions 31 b once or more. Therefore, both ends in the surrounding direction are arranged in the slit 21 so as to overlap.

[0220] That is, in the stator 1, the overlapping portion 10d where the insulating sheets 10 according to this embodiment overlap each other is formed in the slot 21 (see Figure 4 ).

[0221] And, if Figure 4 As shown, in the stator 1 , the overlapping portion 10 d is located on the outside in the radial direction DD.

[0222] It should be noted that the portions protruding from the upper end surface 20a and the lower end surface 20b of the stator core 20 in the rotation axis direction AD may be bent toward the outside of the slot 21 in a manner that is hooked (locked) by at least one of the upper end side and the lower end side of the slot 21 .

[0223] The coil 30 surrounded by the insulating sheet 10 according to the present embodiment is fixed in the slot 21 by the insulating resin (for example, epoxy varnish) by impregnating the slot 21 with the insulating resin.

[0224] Matters disclosed in this specification include the following matters. (1)

[0226] An insulating sheet comprises an adhesive layer and insulating paper, wherein the insulating paper is laminated on one surface of the adhesive layer and constitutes an outermost layer.

[0227] The insulating paper is a wholly aromatic polyamide paper containing wholly aromatic polyamide fibers.

[0228] The adhesive layer is composed of a resin composition, and the temperature at which 5% weight loss is confirmed in thermogravimetric differential thermal analysis (TG-DTA) is 350° C. or less.

[0229] According to this configuration, the insulating sheet can exhibit sufficient anti-tracking properties. (2)

[0231] The insulating sheet according to (1) above, wherein the thickness of the insulating paper is T IP , the thickness of the adhesive layer is set to T AL When the thickness T AL Relative to thickness T IP The ratio is more than 40%.

[0232] According to this configuration, the insulating sheet can more fully exhibit anti-tracking properties. (3)

[0234] The insulating sheet according to (1) or (2), further comprising a base film on the other side of the adhesive layer.

[0235] The substrate film is a polyethylene terephthalate film or a polyethylene naphthalate film.

[0236] According to this configuration, the insulating sheet has excellent heat resistance. (4)

[0238] The insulating sheet according to any one of (1) to (3) above, wherein the adhesive layer is composed of an acrylic resin composition containing an acrylic resin.

[0239] According to this configuration, the insulating sheet can more fully exhibit anti-tracking properties.

[0240] The insulating sheet according to the present invention is not limited to the above-mentioned embodiment.

[0241] In addition, the insulating sheet according to the present invention is not limited to the above-mentioned effects.

[0242] Furthermore, the insulating sheet according to the present invention can be modified in various ways without departing from the spirit and scope of the present invention.

[0243] For example, in the above embodiment, as the insulating sheet 10, an insulating sheet having a 5-layer structure in which a first insulating paper 3a, a first adhesive layer 2a, a base film 1a, a second adhesive layer 2b and a second insulating paper 3b are stacked in sequence is described, but the insulating sheet described in the present invention is not limited to having a 5-layer structure.

[0244] The insulating sheet may have a three-layer structure in which one adhesive layer is sandwiched between two sheets of wholly aromatic polyamide paper as insulating paper from both sides.

[0245] That is, the insulating sheet according to the present invention may have a three-layer structure in which one insulating paper, an adhesive layer, and another insulating paper are laminated in this order.

[0246] Even in such a three-layered insulating sheet, the ratio of carbon atoms generated by thermal decomposition in the adhesive layer can be reduced, thereby suppressing the formation of conductive paths due to the carbon atoms on the outer surface of the wholly aromatic polyamide paper serving as the insulating paper forming the outermost layer.

[0247] In short, the insulating sheet according to the present invention may have a configuration in which a wholly aromatic polyamide paper as insulating paper is provided as an outermost layer, and the adhesive layer is laminated on one surface of the insulating paper.

[0248] Example

[0249] Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. The following Examples are provided to illustrate the present invention in more detail, but are not intended to limit the scope of the present invention.

[0250] (Example 1)

[0251] As the insulating sheet described in Example 1, a sheet (a sheet having five layers) in which layers were stacked in the following order was prepared.

[0252] Fully aromatic polyamide paper (first insulating paper. Thickness: 50μm)

[0253] Acrylic resin layer (first adhesive layer. Thickness: 30 μm)

[0254] Polyethylene terephthalate (PET) film (base film. Thickness: 75 μm)

[0255] Acrylic resin layer (second adhesive layer. Thickness: 30 μm)

[0256] Fully aromatic polyamide paper (second insulating paper. Thickness: 50 μm)

[0257] It should be noted that the thickness of the insulating sheet described in Example 1 is 235 μm.

[0258] In the insulating sheet described in Example 1, the acrylic resin layer (first adhesive layer and second adhesive layer) is formed by applying an acrylic resin solution to a thickness of 30 μm on both sides of a polyethylene terephthalate (PET) film, wherein the acrylic resin solution is obtained by suspending polybutyl acrylate (PAB), terpene phenol and polyisocyanate in an organic solvent (methyl ethyl ketone (MEK)) in a manner such that the solid content concentration becomes 27%.

[0259] The acrylic resin solution was applied to the polyethylene terephthalate (PET) film using a roll coater at a coating gap of 250 μm.

[0260] It should be noted that the viscosity of the acrylic resin solution is about 300 mPa·s.

[0261] In addition, the acrylic resin layer as the first adhesive layer and the second adhesive layer was aged at 130° C. for 24 hours.

[0262] That is, in the insulating sheet described in Example 1, the acrylic resin layer is thermally cured.

[0263] In addition, Nomex (registered trademark) paper manufactured by DuPont was used as the wholly aromatic polyamide paper, and "Melinex (registered trademark) 238" manufactured by DuPont was used as the polyethylene terephthalate (PET) film.

[0264] (Example 2)

[0265] As the insulating sheet described in Example 2, a laminated sheet having a five-layer structure was prepared in the same manner as in Example 1.

[0266] In the insulating sheet described in Example 2, the wholly aromatic polyamide paper serving as the first insulating paper and the second insulating paper is set to a paper with a thickness of 40 μm ("Nomex (registered trademark) paper" manufactured by Dupont), and the PET film serving as the base film is set to a film with a thickness of 125 μm ("Melinex (registered trademark) 238" manufactured by Dupont). Other than that, the structure is the same as that of the insulating sheet described in Example 1.

[0267] It should be noted that the thickness of the insulating sheet described in Example 2 is 265 μm.

[0268] In the insulating sheet according to Example 2, the acrylic resin layer as the first adhesive layer and the second adhesive layer were also aged under the same conditions as in Example 1.

[0269] That is, in the insulating sheet described in Example 2, the acrylic resin layer is also thermally cured.

[0270] (Example 3)

[0271] As the insulating sheet described in Example 3, a laminated sheet having a five-layer structure was prepared in the same manner as in Example 1.

[0272] The insulating sheet of Example 3 had the same configuration as that of the insulating sheet of Example 1 except that the PET film as the base film was a film having a thickness of 125 μm (trade name “Melinex (registered trademark) 238” manufactured by Dupont).

[0273] It should be noted that the thickness of the insulating sheet described in Example 3 is 285 μm.

[0274] In the insulating sheet according to Example 3, the acrylic resin layer as the first adhesive layer and the second adhesive layer were also aged under the same conditions as in Example 1.

[0275] That is, in the insulating sheet described in Example 3, the acrylic resin layer is also thermally cured.

[0276] (Example 4)

[0277] As the insulating sheet described in Example 4, a laminated sheet having a five-layer structure was prepared in the same manner as in Example 1.

[0278] The insulating sheet of Example 4 has the same structure as that of Example 1 except that the wholly aromatic polyamide paper as the first insulating paper and the second insulating paper is 80 μm thick (Nomex (registered trademark) paper manufactured by Dupont).

[0279] It should be noted that the thickness of the insulating sheet described in Example 4 is 295 μm.

[0280] In the insulating sheet according to Example 4, the acrylic resin layer as the first adhesive layer and the second adhesive layer were also aged under the same conditions as in Example 1.

[0281] That is, in the insulating sheet described in Example 4, the acrylic resin layer is also thermally cured.

[0282] (Example 5)

[0283] As the insulating sheet described in Example 5, a laminated sheet having a five-layer structure was prepared in the same manner as in Example 1.

[0284] The insulating sheet according to Example 5 had the same configuration as that of the insulating sheet according to Example 1 except that the thickness of the acrylic resin layer as the first adhesive layer and the second adhesive layer was set to 10 μm.

[0285] It should be noted that the thickness of the insulating sheet described in Example 5 is 195 μm.

[0286] In the insulating sheet described in Example 5, the acrylic resin layer is formed by applying an acrylic resin solution to a thickness of 10 μm on both sides of a polyethylene terephthalate (PET) film, wherein the acrylic resin solution is obtained by suspending polybutyl acrylate (PAB), terpene phenol and polyisocyanate in a solid content concentration of 19%.

[0287] The acrylic resin solution was applied to the polyethylene terephthalate (PET) film using a roll coater at a coating gap of 70 μm.

[0288] It should be noted that the viscosity of the acrylic resin solution is about 300 mPa·s.

[0289] In the insulating sheet according to Example 5, the acrylic resin layer as the first adhesive layer and the second adhesive layer were also aged under the same conditions as in Example 1.

[0290] That is, in the insulating sheet described in Example 5, the acrylic resin layer is also thermally cured.

[0291] (Example 6)

[0292] As the insulating sheet described in Example 6, a laminated sheet having a five-layer structure was prepared in the same manner as in Example 1.

[0293] The insulating sheet according to Example 6 had the same configuration as that of the insulating sheet according to Example 1 except that the thickness of the acrylic resin layer as the first adhesive layer and the second adhesive layer was set to 20 μm.

[0294] It should be noted that the thickness of the insulating sheet described in Example 6 is 215 μm.

[0295] In the insulating sheet described in Example 6, the acrylic resin layer is formed by applying an acrylic resin solution to a thickness of 20 μm on both sides of a polyethylene terephthalate (PET) film, wherein the acrylic resin solution is obtained by suspending polybutyl acrylate (PAB), terpene phenol and polyisocyanate in a solid content concentration of 27%.

[0296] The acrylic resin solution was applied to the polyethylene terephthalate (PET) film using a roll coater at a coating gap of 170 μm.

[0297] It should be noted that the viscosity of the acrylic resin solution is about 300 mPa·s.

[0298] In the insulating sheet according to Example 6, the acrylic resin layer as the first adhesive layer and the second adhesive layer were also aged under the same conditions as in Example 1.

[0299] That is, in the insulating sheet described in Example 6, the acrylic resin layer is also thermally cured.

[0300] (Example 7)

[0301] As the insulating sheet described in Example 7, a laminated sheet having a five-layer structure was prepared in the same manner as in Example 1.

[0302] The insulating sheet according to Example 7 had the same configuration as that of the insulating sheet according to Example 1 except that the first adhesive layer and the second adhesive layer were urethane resin layers (thickness 10 μm).

[0303] It should be noted that in the insulating sheet described in Example 7, the polyurethane resin layer (the first adhesive layer and the second adhesive layer) is formed by applying a polyurethane resin solution (product name "TYFORCE SA-30-L" manufactured by DIC Corporation) to a thickness of 10 μm on both sides of a polyethylene terephthalate (PET) film, and the polyurethane resin solution is obtained by suspending a substance obtained by urethane bonding a polyol component and an isocyanate component in an organic solvent (a mixed organic solvent of toluene (TOL) and methyl ethyl ketone (MEK)) in a manner such that the solid content concentration is 25%.

[0304] The urethane resin solution was applied to the polyethylene terephthalate (PET) film using a roll coater at a coating gap of 70 μm.

[0305] In the insulating sheet described in Example 7, the urethane adhesive layer as the first adhesive layer and the second adhesive layer was aged at 130° C. for 24 hours.

[0306] That is, in the insulating sheet described in Example 7, the urethane resin layer is thermally cured.

[0307] (Comparative Example 1)

[0308] As the insulating sheet described in Comparative Example 1, a laminated sheet having a five-layer structure was prepared in the same manner as in Example 1.

[0309] In the insulating sheet described in Comparative Example 1, the first adhesive layer and the second adhesive layer are set as a mixed resin layer (thickness 10μm) of an acrylic resin (polybutyl acrylate (PAB)) and an epoxy resin (phenol novolac type epoxy resin. The epoxy equivalent is 176g / eq~180g / eq) and a curing agent (phenol-based curing agent) of the aforementioned epoxy resin. Other than that, the structure is the same as the insulating sheet described in Example 1.

[0310] It should be noted that the thickness of the insulating sheet described in Comparative Example 1 was 195 μm.

[0311] In addition, in the insulating sheet described in Comparative Example 1, the mixed resin layer (first adhesive layer and second adhesive layer) is formed by applying a mixed resin solution to a thickness of 10 μm on both sides of a polyethylene terephthalate (PET) film, and the mixed resin solution is obtained by further adding a phenol novolac type epoxy resin, a phenolic curing agent and a curing accelerator to an organic solvent (methyl ethyl ketone (MEK)) containing polybutyl acrylate (PAB).

[0312] In addition, 140 parts by mass of the polybutyl acrylate was contained based on 100 parts by mass of the organic solvent, and 60 parts by mass of the phenol novolac-type epoxy resin was contained based on 100 parts by mass of the organic solvent.

[0313] Moreover, the phenolic curing agent is contained in an amount of 45 parts by mass and the curing accelerator is contained in an amount of 3 parts by mass based on 100 parts by mass of the phenol novolac epoxy resin.

[0314] The mixed resin solution was applied to the polyethylene terephthalate (PET) film using a roll coater at a coating gap of 70 μm.

[0315] In the insulating sheet described in Comparative Example 1, the mixed resin layer as the first adhesive layer and the second adhesive layer was aged at 130° C. for 24 hours.

[0316] That is, in the insulating sheet described in Comparative Example 1, the mixed resin layer is also thermally cured.

[0317] <Evaluation of Thermal Decomposition by Thermogravimetric Differential Thermal Analysis (TG-DTA)>

[0318] The thermal decomposition property of the adhesive layer of each example was evaluated by thermogravimetric differential thermal analysis (TG-DTA).

[0319] Specifically, the evaluation was performed according to the following procedures.

[0320] (1) The resin composition described in each example was applied to the entire surface of one side of a release paper, and then dried at 100° C. for 1 minute to prepare a release paper with an adhesive layer for each example.

[0321] In addition, coating was performed so that the thickness of the adhesive layer after drying might become 12 micrometers.

[0322] (2) The release paper with an adhesive layer of each example was placed in an oven at a predetermined temperature for a predetermined period of time to allow a curing reaction to proceed in the adhesive layer.

[0323] In addition, the release paper with an adhesive layer of each example was placed in an oven at 130° C. for 24 hours to perform a curing reaction.

[0324] After the curing reaction proceeded, the release paper was peeled off from the release paper with the adhesive layer in each example.

[0325] (3) Using a thermogravimetric differential thermal analyzer (manufactured by SII Nano Technology, model "EXSTAR6000"), the temperature was raised from room temperature (23±2°C) at a rate of 10°C / min in an atmosphere of 100 mL / min of air to obtain a TG-DTA curve of the adhesive layer described in each example after being peeled off from the release paper. The temperature at which a weight loss of 5% by mass was confirmed was read.

[0326] The temperature at which 5% weight loss was observed for the adhesive layer described in each example (5% weight loss temperature) was read, and the results are shown in Table 1 below.

[0327] <Evaluation of tracking resistance (CTI)>

[0328] The test is carried out according to the standards of the International Electrical Standards Conference, specifically IEC60112.

[0329] In detail, prepare 20 flat test samples with a size of 100mm×100mm and a thickness of 3mm or more. Place a platinum electrode on the surface of the test sample, apply a voltage between the electrodes, and drip an electrolyte (0.1% by mass ammonium chloride aqueous solution) between the electrodes at a specified interval while the voltage is applied. Continue the test until leakage tracking occurs or the number of drops reaches 100. Then, count the number of drops of electrolyte required until leakage tracking occurs. Perform 5 tests for each voltage. If the number of drops counted is more than 50 drops, it is judged to be qualified under the applied voltage. Repeat this operation at various voltages at intervals of 25V to calculate the CTI (comparative leakage tracking index).

[0330] The tracking resistance (CTI) was evaluated for each example, and the results are shown in Table 1 below.

[0331] It should be noted that the thickness T of the adhesive layer is also shown in Table 1 below. AL (T AL1 +T AL2 ) relative to the thickness of the insulating paper T IP (T IP1 +T IP2 ) ratio, and the thickness T of the adhesive layer AL Relative to the thickness T of the insulation sheet T ratio.

[0332] [Table 1]

[0333]

[0334] According to Table 1, in the insulating sheets described in the embodiments, the 5% weight loss temperature is below 350°C, and the evaluation result of the tracking resistance is above 400V. In contrast, in the insulating sheets described in Comparative Example 1, the 5% weight loss temperature is 357°C, which is higher than 350°C, and the evaluation result of the tracking resistance is 375V, which is lower than 400V.

[0335] From this result, it is considered that an insulating sheet excellent in tracking resistance can be obtained by setting the 5% weight loss temperature to 350° C. or less.

[0336] In addition, it can be seen from Table 1 that by AL Relative to thickness T IP When the ratio was set to 40% or more, the evaluation results of the tracking resistance showed high values ​​of 525 V or more (Examples 1 to 3 and Example 6).

[0337] According to this result, it can be considered that if the thickness T AL Relative to thickness T IP When the ratio of is 40% or more, an insulating sheet having more excellent tracking resistance can be obtained.

[0338] Description of Reference Numerals

[0339] 1stator, 10insulating sheet, 20stator core, 21slot, 22plate-shaped protrusion (tooth portion), 30coil, 31divided conductor,

[0340] 1a substrate film, 2a first adhesive layer, 2b second adhesive layer, 3a first insulating paper, 3b second insulating paper,

[0341] 10d overlapping portion, 20a end surface (upper end surface), 20b end surface (lower end surface), 21a linear opening portion, 21b opening portion, 22a wide portion, 31a head portion, 31b foot portion, 31bx front end portion, 31x connection portion,

[0342] AD is the rotation axis direction, DD is the radial direction, and RD is the circumferential direction.

Claims

1. An insulating sheet comprising an adhesive layer and insulating paper, wherein the insulating paper is laminated on one surface of the adhesive layer and constitutes an outermost layer, The insulating paper is a wholly aromatic polyamide paper containing wholly aromatic polyamide fibers, The adhesive layer is composed of a resin composition, and a temperature at which a weight loss of 5% by mass is confirmed in thermogravimetric differential thermal analysis (TG-DTA) is 350° C. or less.

2. The insulating sheet according to claim 1, wherein: The thickness of the insulating paper is set to T IP , the thickness of the adhesive layer is set to T AL When the thickness T AL Relative to thickness T IP The ratio is more than 40%.

3. The insulating sheet according to claim 1 or 2, wherein: A base film is further provided on the other side of the adhesive layer. The substrate film is a polyethylene terephthalate film or a polyethylene naphthalate film.

4. The insulating sheet according to claim 1 or 2, wherein: The adhesive layer is composed of an acrylic resin composition containing an acrylic resin.

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