Insulating film for motor, interphase insulating paper, slot paper, and wedge paper

Abstract

Provided is an insulating film for a motor, the film containing a resin composition comprising a 3-methyl-1-butene polymer.

Description

Motor insulating film, interphase insulating paper, slot paper, and wedge paper

[0001] The present invention relates to an insulating film for a motor, an interphase insulating paper, a slot paper, and a wedge paper.

[0002] Electric vehicles are becoming increasingly popular as an energy-efficient means of transportation. Electric vehicles are equipped with a motor generator that can selectively function as an electric motor or a generator. This motor generator consists of a cylindrical rotor, a motor stator located on its outer periphery, and a motor housing that houses the rotor. The motor stator is composed of a core material and windings. Insulating materials, such as insulating films and sheets, are used to insulate the core material from the windings or between windings of different phases. Examples of such insulating films and sheets include insulating paper, such as aramid paper made of aramid fibrid and aramid short fibers, and plastic films, such as polyphenylene sulfide film, polyimide film, polyether ether ketone film, polyethylene terephthalate film, and polyethylene naphthalate film, as well as laminated sheets of these materials. Patent Document 1 (Patent Document 1) describes an insulating sheet that is a laminate containing aramid paper.

[0003] Japanese Patent Application Laid-Open No. 2008-119999

[0004] In recent years, there has been an increasing demand for electric vehicles with high-speed charging and high output. Accordingly, insulating films and insulating sheets are required to have a low relative dielectric constant and a low dielectric loss tangent, while also being resistant to high voltages and heat generated by coils incorporated in electric motors, generators, etc., and electronic devices. However, conventional insulating films and insulating sheets have not been able to withstand both high voltages and heat generated by coils, electronic devices, etc.

[0005] In view of the current situation, an object of the present invention is to provide an insulating film for a motor that has a low relative dielectric constant and a low dielectric loss tangent, and is excellent in voltage resistance and heat resistance, as well as interphase insulating paper, slot paper, and wedge paper that include the insulating film for a motor.

[0006] As a result of intensive research to solve the above problems, the present inventors have conceived the following invention and found that the above problems can be solved.

[0007] [1] An insulating film for motors, comprising a resin composition containing a 3-methyl-1-butene polymer. [2] The insulating film for motors according to [1], wherein the 3-methyl-1-butene polymer is at least one selected from the group consisting of a 3-methyl-1-butene homopolymer and a copolymer of 3-methyl-1-butene with ethylene or an α-olefin, wherein the α-olefin is an α-olefin having 3 to 20 carbon atoms. [3] The insulating film for motors according to [2], wherein the copolymer contains structural units derived from ethylene or an α-olefin in an amount of more than 0 mol% and not more than 20 mol%. [4] The insulating film for motors according to any one of [1] to [3], wherein the comparative tracking index measured in accordance with JIS C 2134:2007 is 600 V or more. [5] The insulating film for motors according to any one of [1] to [4], wherein the thickness is 50 μm or more and 1000 μm or less. [6] The motor insulating film according to [2] above, wherein the copolymer contains more than 50 mol% and less than 100 mol% of the structural unit derived from 3-methyl-1-butene. [7] Phase insulating paper comprising the motor insulating film according to any one of [1] to [6] above. [8] Slot paper comprising the motor insulating film according to any one of [1] to [6] above. [9] Wedge paper comprising the motor insulating film according to any one of [1] to [6] above.

[0008] According to the present invention, it is possible to provide an insulating film for a motor that has a low relative dielectric constant and a low dielectric loss tangent, as well as excellent voltage resistance and heat resistance, as well as interphase insulating paper, slot paper, and wedge paper that include the insulating film for a motor.

[0009] The following is a description based on one example of an embodiment of the present invention. However, the embodiment shown below is an example for embodying the technical idea of ​​the present invention, and the present invention is not limited to the following description. In this specification, preferred embodiments are shown, but a combination of two or more of the individual preferred embodiments is also a preferred embodiment. For matters shown as numerical ranges, when there are several numerical ranges, the lower limit and upper limit can be selectively combined to form a preferred embodiment. In this specification, when a numerical range is described as "XX to YY," it means "XX or more and YY or less."

[0010] <Insulating Film for Motors> The insulating film for motors of this embodiment contains a resin composition containing a 3-methyl-1-butene polymer. The resin composition contained in the insulating film for motors contains a 3-methyl-1-butene polymer, which provides a low relative permittivity and a low dielectric loss tangent, as well as excellent voltage resistance and heat resistance. Furthermore, the insulating film for motors of this embodiment has excellent voltage resistance, making it usable even in high-voltage environments. Furthermore, because of its excellent heat resistance, it is less likely to deform even when coils incorporated in electric motors, generators, and the like, or electronic devices, generate heat, and has excellent dimensional stability. Furthermore, the 3-methyl-1-butene polymer has a relatively low specific gravity, which can contribute to weight reduction.

[0011] The insulating film for a motor of the present embodiment may be made of a resin composition, or may contain components other than the resin composition.

[0012] [Resin Composition] The resin composition of the present embodiment contains a 3-methyl-1-butene polymer.

[0013] <3-Methyl-1-butene Polymer> The 3-methyl-1-butene polymer is a polymer containing at least a structural unit derived from 3-methyl-1-butene. The 3-methyl-1-butene polymer may be a 3-methyl-1-butene homopolymer or a copolymer of 3-methyl-1-butene and an unsaturated hydrocarbon. Examples of the unsaturated hydrocarbon include ethylene and an α-olefin. In this embodiment, the α-olefin used in the 3-methyl-1-butene polymer refers to an α-olefin other than 3-methyl-1-butene. In other words, the α-olefin refers to an α-olefin other than 3-methyl-1-butene, and is also expressed as α-olefin (excluding 3-methyl-1-butene). From the viewpoint of good copolymerizability, the unsaturated hydrocarbon is preferably ethylene or an α-olefin having 3 to 20 carbon atoms. From the viewpoint of favorably exhibiting mechanical properties (adequate strength, flexibility, and impact resistance), the 3-methyl-1-butene polymer is preferably at least one selected from the group consisting of a 3-methyl-1-butene homopolymer and a copolymer of 3-methyl-1-butene with ethylene or an α-olefin having 3 to 20 carbon atoms, and more preferably a copolymer of 3-methyl-1-butene with ethylene or an α-olefin having 3 to 20 carbon atoms. A copolymer of 3-methyl-1-butene with ethylene or an α-olefin having 3 to 20 carbon atoms refers to a copolymer of 3-methyl-1-butene with ethylene or a copolymer of 3-methyl-1-butene with an α-olefin having 3 to 20 carbon atoms. Hereinafter, a copolymer of 3-methyl-1-butene with ethylene or an α-olefin will also be referred to simply as a "copolymer." The copolymer may be a random copolymer, a block copolymer, or an alternating copolymer. The method for producing the copolymer is not limited as long as it does not impair the effects of the present invention, and known copolymerization methods can be used.

[0014] When the 3-methyl-1-butene polymer is the copolymer, the content of structural units derived from ethylene or an α-olefin in 100 mol% of the copolymer is preferably more than 0 mol% and not more than 20 mol%. From the viewpoints of flexibility and impact resistance, the content of structural units derived from ethylene or an α-olefin in 100 mol% of the copolymer is more preferably 0.1 mol% or more, even more preferably 0.5 mol% or more, and still more preferably 1.0 mol% or more. From the viewpoints of voltage resistance and heat resistance, the content of structural units derived from ethylene or an α-olefin in 100 mol% of the copolymer is more preferably 15 mol% or less, even more preferably 10 mol% or less, and still more preferably 7.0 mol% or less. From these viewpoints, the content of structural units derived from ethylene or an α-olefin in 100 mol% of the copolymer is more preferably 0.1 to 15 mol%, even more preferably 0.5 to 10 mol%, still more preferably 0.5 to 7.0 mol%, and still more preferably 1.0 to 7.0 mol%. In one embodiment, the content of structural units derived from ethylene or an α-olefin in 100 mol % of the copolymer is more preferably more than 0 mol % and 10 mol % or less. The content of structural units derived from ethylene or an α-olefin in the copolymer can be determined using a Fourier transform infrared spectrophotometer (FT-IR). Specifically, it can be measured by the method described in the Examples.

[0015] When the 3-methyl-1-butene polymer is the copolymer, the content of structural units derived from 3-methyl-1-butene in 100 mol% of the copolymer is preferably more than 50 mol% and less than 100 mol%, and more preferably 80 mol% or more and less than 100 mol%. From the viewpoints of voltage resistance and heat resistance, the content of structural units derived from 3-methyl-1-butene in 100 mol% of the copolymer is preferably more than 50 mol%, more preferably 70 mol% or more, even more preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, still more preferably 92 mol% or more, and still more preferably 93 mol% or more. From the viewpoints of flexibility and impact resistance, the content of structural units derived from 3-methyl-1-butene in 100 mol% of the copolymer is more preferably 99.9 mol% or less, and even more preferably 99.5 mol% or less. From these viewpoints, the content of structural units derived from 3-methyl-1-butene in the copolymer is more preferably 85 to 99.9 mol%, even more preferably 90 to 99.5 mol%, still more preferably 92 to 99.5 mol%, and even more preferably 93 to 99.5 mol%.

[0016] From the viewpoint of favorably exhibiting the physical properties of the 3-methyl-1-butene polymer, the ethylene or α-olefin is preferably an α-olefin having 3 to 20 carbon atoms, more preferably an α-olefin having 4 to 16 carbon atoms, even more preferably an α-olefin having 4 to 12 carbon atoms, still more preferably an α-olefin having 4 to 10 carbon atoms, and still more preferably an α-olefin having 6 to 10 carbon atoms. The α-olefin having 3 to 20 carbon atoms may be linear, branched, cyclic, or may contain a cyclic moiety.

[0017] Examples of the α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, vinylcyclohexene, and vinylnorbornane. The α-olefin having 3 to 20 carbon atoms is preferably a linear α-olefin, more preferably at least one selected from the group consisting of 1-butene, 1-octene, 1-nonene, and 1-decene, even more preferably at least one selected from the group consisting of 1-octene, 1-nonene, and 1-decene, and still more preferably 1-decene. The α-olefin having 3 to 20 carbon atoms may be used alone or in combination of two or more.

[0018] The melting point of the 3-methyl-1-butene polymer is preferably 260 to 310°C. When the melting point of the 3-methyl-1-butene polymer is within the above range, the resin composition can be easily molded by injection molding or the like, and the heat resistance is improved. The melting point of the 3-methyl-1-butene polymer refers to the peak temperature measured using a differential scanning calorimeter by heating a test piece (3-methyl-1-butene polymer) from 30°C to 320°C at a rate of 10°C / min under a nitrogen flow rate (100 mL / min), holding at 320°C for 5 minutes, cooling to -70°C at 10°C / min, holding at -70°C for 5 minutes, and then heating to 320°C at a rate of 10°C / min. Specifically, the melting point can be measured by the method described in the Examples. From the viewpoint of the balance between production efficiency and heat resistance, the melting point of the 3-methyl-1-butene polymer is more preferably 270 to 305°C, even more preferably 280 to 305°C, and still more preferably 280 to 300°C.

[0019] The melt viscosity of the 3-methyl-1-butene polymer of this embodiment is preferably 10 to 1,000 Pa s. When the melt viscosity of the 3-methyl-1-butene polymer is 10 Pa s or more, the mechanical strength is further improved, and when it is 1,000 Pa s or less, good fluidity during molding is easily obtained. From the viewpoint of the balance between mechanical strength and fluidity during molding, the melt viscosity of the 3-methyl-1-butene polymer is more preferably 30 to 500 Pa s, even more preferably 50 to 300 Pa s, and still more preferably 80 to 150 Pa s. The melt viscosity of the 3-methyl-1-butene polymer of this embodiment is measured using a capillary rheometer at a barrel temperature of 320°C and a shear rate of 1,220 sec. －１ The term "capillary" refers to a value measured under the conditions of (capillary: inner diameter 1.0 mm x length 10 mm, extrusion rate 10 mm / min), and specifically can be measured by the method described in the examples.

[0020] The content of the 3-methyl-1-butene polymer in 100% by mass of the resin composition is preferably 80.0 to 99.9% by mass, more preferably 85.0 to 99.9% by mass, and even more preferably 90.0 to 99.9% by mass, from the viewpoint of obtaining an insulating film for a motor that has a lower relative dielectric constant and a lower dielectric loss tangent and is excellent in voltage resistance and heat resistance.

[0021] 3-methyl-1-butene polymers have a relatively low specific gravity and can contribute to weight reduction of insulating films for motors. Furthermore, 3-methyl-1-butene polymers do not generate harmful gases when incinerated. Furthermore, the decomposition products of 3-methyl-1-butene polymers in an inert atmosphere are low-molecular-weight hydrocarbons, making them suitable for chemical recycling.

[0022] <Alkyl Radical Scavenger> The resin composition may contain an alkyl radical scavenger from the viewpoint of exhibiting better mechanical properties. In this embodiment, the term "alkyl radical scavenger" refers to a compound that reacts with an alkyl radical derived from the 3-methyl-1-butene polymer and then stabilizes the radical, thereby suppressing a chain reaction of main chain scission initiated by the alkyl radical. From the viewpoint of exhibiting better mechanical properties, the alkyl radical scavenger preferably contains at least one compound selected from the group consisting of an acrylic phenol compound and a benzofuranone compound. One alkyl radical scavenger may be used alone, or two or more alkyl radical scavengers may be used in combination.

[0023] (Acrylphenol Compound) The acrylic phenol compound used in this embodiment can be represented by, for example, the following general formula (I).

[0024]

[0025] In general formula (I), R １ represents a hydrogen atom or a methyl group, and R ２ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ３ , R ４ , R ５ and R ６ each independently represents an alkyl group having 1 to 9 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. The alkyl group having 1 to 9 carbon atoms may be linear or branched. Examples of the alkyl group having 1 to 9 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, a 1,1-dimethylpropyl group, a 1,2-dimethylpropyl group, a 2,2-dimethylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, and an n-nonyl group. R １ is preferably a hydrogen atom. ２ is preferably a hydrogen atom or a methyl group, more preferably a methyl group.３ , R ４ , R ５ and R ６ are each independently preferably an alkyl group having 3 to 8 carbon atoms, more preferably an alkyl group having 5 carbon atoms, and even more preferably a 1,1-dimethylpropyl group.

[0026] Examples of the acrylic phenol compound represented by general formula (I) include 2,4-di-t-amyl-6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate, 2,4-di-t-butyl-6-[1-(3,5-di-t-butyl-2-hydroxyphenyl)ethyl]phenyl acrylate, and 2-t-butyl-6-[(3-t-butyl-2-hydroxy-5-methylphenyl)methyl]-4-methylphenyl acrylate. Commercially available alkyl radical scavengers may be used, and examples of the acrylic phenol compound represented by general formula (I) include those available under the trade names "Sumilizer (registered trademark) GS" and "Sumilizer (registered trademark) GM" manufactured by Sumitomo Chemical Co., Ltd.

[0027] (Benzofuranone Compound) The benzofuranone compound used in this embodiment can be represented by, for example, the following general formula (II).

[0028]

[0029] In general formula (II), R ７ and R ８ each independently represents an alkyl group having 1 to 4 carbon atoms; R ９ and R １０each independently represents an alkyl group having 1 to 9 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, and a t-butyl group. The alkyl group having 1 to 9 carbon atoms may be linear or branched. Examples of the alkyl group having 1 to 9 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, a 1,1-dimethylpropyl group, a 1,2-dimethylpropyl group, a 2,2-dimethylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, and an n-nonyl group. R ７ and R ８ are each independently preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group. ９ and R １０ are each independently preferably an alkyl group having 1 to 4 carbon atoms, more preferably a t-butyl group.

[0030] Examples of the benzofuranone compound represented by general formula (II) include 5,7-di-t-butyl-3-(3,4-di-methyl-phenyl)-3H-benzofuran-2-one, 5,7-di(t-butyl)-3-(3,4-di-propyl-phenyl)-3H-benzofuran-2-one, etc. Commercially available alkyl radical scavengers may be used, and examples of the benzofuranone compound represented by general formula (II) include "Irganox (registered trademark) HP-136" manufactured by BASF Japan Ltd. and "Revonox (registered trademark) 501" manufactured by Chitec Corporation.

[0031] (Alkyl Radical Scavenger Content) The content of the alkyl radical scavenger in the resin composition relative to 100 parts by mass of the 3-methyl-1-butene polymer is preferably 0.01 to 1.00 parts by mass. When the alkyl radical scavenger content is 0.01 parts by mass or more, the physical properties of the resin composition can be more stably maintained during melt-kneading of the resin composition. Furthermore, generation of decomposition gas during melt molding, which can result in molding defects, can be suppressed. Furthermore, when the alkyl radical scavenger content is 1.00 parts by mass or less, an insulating film for motors with more excellent mechanical properties can be easily obtained. Furthermore, impairment of the physical properties required of the resin composition, such as bleeding out of the alkyl radical scavenger or deterioration of moisture absorption, can be suppressed.

[0032] From the viewpoint of maintaining the physical properties of the resin composition more stably during melt-kneading, the content of the alkyl radical scavenger in the resin composition per 100 parts by mass of the 3-methyl-1-butene polymer is more preferably 0.02 parts by mass or more, and even more preferably 0.05 parts by mass or more. Furthermore, from the viewpoint of a balance between maintaining the stability of the physical properties of the resin composition and economic efficiency, and from the viewpoint of obtaining an insulating film for a motor having a lower dielectric constant and a lower dielectric loss tangent, the content of the alkyl radical scavenger in the resin composition per 100 parts by mass of the 3-methyl-1-butene polymer is more preferably 0.80 parts by mass or less, and even more preferably 0.70 parts by mass or less. From these viewpoints, the content of the alkyl radical scavenger in the resin composition per 100 parts by mass of the 3-methyl-1-butene polymer is more preferably 0.02 to 0.80 parts by mass, and even more preferably 0.05 to 0.70 parts by mass. When two or more alkyl radical scavengers are contained, the content of the alkyl radical scavengers refers to the total content of the alkyl radical scavengers.

[0033] <Antioxidant> The resin composition may contain an antioxidant from the viewpoint of ensuring the stability of the polymer. The antioxidant preferably contains at least one selected from the group consisting of phenolic antioxidants and phosphorus-based antioxidants. One type of antioxidant may be used alone, or two or more types may be used in combination.

[0034] (Phenol-Based Antioxidant) Examples of the phenol-based antioxidant include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris[(4-t-butyl-3-hydroxy-2,6-xylyl)methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and octaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]. Decyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, thiodiethylene-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'-hexane-1,6-diylbis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionamide], 3,3',3'',5,5',5''-hexa-t-butyl-α,α',α''-(mesitylene-2,4,6-triyl)tri-p-cresol, ethylene bis (oxyethylene)bis[3-(5-t-butyl-4-hydroxy-m-tolyl)propionate], hexamethylene-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,6-di-t-butyl-4-[4,6-bis(octylthio)-1,3,5-triazin-2-ylamino]phenol, 3,9-bis[2-(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl]-2, Examples include 4,8,10-tetraoxaspiro(5,5)undecane, 4,4',4''-(1-methylpropanyl-3-ylidene)tris(6-t-butyl-m-cresol), 6,6'-di-t-butyl-4,4'-butylidene-m-cresol, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and benzenepropionic acid 3,5-bis-(1,1-dimethylethyl)-4-hydroxy-C7-C9 branched alkyl ester.

[0035] As the phenolic antioxidant, commercially available products may be used, such as "ADEKA STAB (registered trademark) AO series" manufactured by ADEKA Corporation and "Irganox (registered trademark) series" manufactured by BASF Japan Ltd.

[0036] (Phosphorus-Based Antioxidant) Examples of the phosphorus-based antioxidant include 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, tetrakis(2,4-di-t-butyl-phenyl)-4,4′-biphenylenephosphonite, 2,2-methylenebis(4,6-di-t-butylphenyl)octylphosphite, and tris(2,4-di-t-butylphenyl)phosphite. phosphate, bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl)ethyl ester phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, di-t-butyl-m-cresyl-phosphonite, diethyl [(3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)methyl]phosphonate, tris(2,4-di-t-butylphenyl)phosphite, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene diphosphonite, 3,9-bis(octadecyoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, tris(2,4-di-t-butylphenyl)phosphite, tris(nonylphenyl)phosphite, tetra-C12-15-alkyl (propane-2,2-diylbis(4,1-phenylene))bis(phosphite), 2-ethylhexyldiphenyl phosphite, isodecyldiphenyl phosphite, trisisodecyl phosphite, triphenyl phosphite, and 3,9-bis[2,4-bis(1-methyl-1-phenylethyl)phenoxy]-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane.

[0037] As the phosphorus-based antioxidant, commercially available products may be used, and examples thereof include "ADK STAB (registered trademark) PEP series" and "ADK STAB (registered trademark) HP series" manufactured by ADEKA Corporation, "Irgafos (registered trademark) series" manufactured by BASF Japan Ltd., and "HOSTANOX (registered trademark) P-EPQ" manufactured by Clariant.

[0038] (Sulfur-Based Antioxidants) Examples of sulfur-based antioxidants include dilauryl 3,3′-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, laurylstearyl 3,3′-thiodipropionate, pentaerythritol-tetrakis-(β-lauryl-thio-propionate), 3,9-bis(2-dodecylthioethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, and the like.

[0039] (Other Antioxidants) The resin composition may contain other antioxidants besides the phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants, as long as the effects of the present invention are not impaired. Examples of antioxidants other than the phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants include amine-based antioxidants.

[0040] (Antioxidant Content) The content of the antioxidant in the resin composition relative to 100 parts by mass of the 3-methyl-1-butene polymer is preferably 0.01 parts by mass or more, more preferably 0.10 parts by mass or more, from the viewpoint of ensuring the stability of the 3-methyl-1-butene polymer, and is preferably 1.00 parts by mass or less, more preferably 0.80 parts by mass or less, from the viewpoint of the relative dielectric constant and the dielectric loss tangent. That is, the content is preferably 0.01 to 1.00 parts by mass, more preferably 0.10 to 0.80 parts by mass. When the resin composition contains two or more antioxidants, the content of the antioxidants refers to the total content of the antioxidants.

[0041] <Other Additives> The resin composition may contain additives other than the alkyl radical scavenger and the antioxidant. Examples of the other additives include antacids, fillers, light stabilizers, antistatic agents, flame retardants, pigments, polymerization inhibitors, heavy metal deactivators, UV absorbers, nucleating agents, clarifying agents, lubricants, fluorescent brighteners, rust inhibitors, and sliding agents. One of the other additives may be used alone, or two or more may be used in combination.

[0042] (Antacid Agent) From the viewpoint of suppressing deterioration due to acid components generated from residual metals and the like during melt-kneading, the resin composition preferably contains an antacid. Examples of antacid agents include barium laurate, calcium stearate, zinc stearate, magnesium stearate, aluminum stearate, zinc oleate, and magnesium 12-hydroxystearate. One type of antacid agent may be used alone, or two or more types may be used in combination.

[0043] The content of the antacid in the resin composition relative to 100 parts by mass of the 3-methyl-1-butene polymer can be determined as appropriate and may be, for example, 0.01 to 200 parts by mass, 0.01 to 2.0 parts by mass, or 0.01 to 1.0 part by mass.

[0044] (Antistatic Agent) Examples of the antistatic agent include sodium alkylsulfonate, phosphonium alkylsulfonate, and fatty acid ester hydroxyamine compounds, which are glycerin esters of stearic acid.

[0045] The content of the antistatic agent in the resin composition relative to 100 parts by mass of the 3-methyl-1-butene polymer can be determined appropriately, and may be, for example, 5 parts by mass or less.

[0046] (Filler) The resin composition may contain a filler from the viewpoint of further improving the mechanical properties of the insulating film for motors. Examples of fillers include fibrous compounds such as glass fibers, alumina fibers, resin fibers, carbon fibers, and cellulose fibers; flat compounds such as mica, talc, montmorillonite, and tabular aluminum; spherical compounds such as glass beads, shirasu balloons, and acrylic balloons; acicular compounds such as acicular metal titanates, wollastonite, acicular silica, and tin oxide; and powdered compounds such as powdered metal titanates, finely powdered wood chips, titanium oxide, calcium carbonate, silica, and alumina. These fillers may be surface-treated with, for example, a silane coupling agent. A compatibilizer may also be used to enhance the dispersibility of the filler. Among these, glass fibers are preferred from the viewpoint of further improving the mechanical properties of the insulating film for motors. One filler may be used alone, or two or more fillers may be used in combination.

[0047] The content of the filler in the resin composition relative to 100 parts by mass of the 3-methyl-1-butene polymer can be determined appropriately and may be, for example, 0.01 to 300 parts by mass or 0.1 to 100 parts by mass.

[0048] (Ultraviolet Absorber) Examples of the ultraviolet absorber include hindered amine ultraviolet absorbers such as 2,2,6,6-tetramethyl-4-piperidyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate, and 4-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)-1-(2-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)ethyl)-2,2,6,6-tetramethylpiperidine; Benzotriazole-based ultraviolet absorbers such as 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(3-t-butyl-2-hydroxy-5-methylphenyl)-5-chlorobenzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, and 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole; and benzoate-based ultraviolet absorbers such as 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate and hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate.

[0049] The content of the ultraviolet absorber in the resin composition relative to 100 parts by mass of the 3-methyl-1-butene polymer can be determined as appropriate and may be, for example, 0.001 to 5 parts by mass or 0.01 to 1 part by mass.

[0050] (Lubricant) Inorganic fine particles are generally used as the lubricant. Examples of the inorganic fine particles include particles of oxides, hydroxides, sulfides, nitrides, halides, carbonates, sulfates, acetates, phosphates, phosphites, organic carboxylates, silicates, titanates, borates, and hydrated compounds thereof, composite compounds mainly composed of these, and natural minerals, of elements of Groups 1, 2, 4, 6, 7, 8 to 10, 11, 12, 13, and 14 of the periodic table.

[0051] Examples of inorganic fine particles include Group 1 element compounds such as lithium fluoride and borax (sodium borate hydrate); Group 2 element compounds such as magnesium carbonate, magnesium phosphate, magnesium oxide (magnesiu), magnesium chloride, magnesium acetate, magnesium fluoride, magnesium titanate, magnesium silicate, magnesium silicate hydrate (talc), calcium carbonate, calcium phosphate, calcium phosphite, calcium sulfate (gypsum), calcium acetate, calcium terephthalate, calcium hydroxide, calcium silicate, calcium fluoride, calcium titanate, strontium titanate, barium titanate, zinc titanate, lanthanum titanate, bismuth titanate, lead titanate, barium carbonate, barium phosphate, barium sulfate, and barium phosphite; titanium dioxide (titania Group 4 element compounds such as titanium monoxide, titanium nitride, zirconium dioxide (zirconia), and zirconium monoxide; Group 6 element compounds such as molybdenum dioxide, molybdenum trioxide, and molybdenum sulfide; Group 7 element compounds such as manganese chloride and manganese acetate; Group 8 to 10 element compounds such as cobalt chloride and cobalt acetate; Group 11 element compounds such as cuprous iodide; Group 12 element compounds such as zinc oxide and zinc acetate; Group 13 element compounds such as aluminum oxide (alumina), aluminum hydroxide, aluminum fluoride, and aluminosilicates (alumina silicate, kaolin, and kaolinite); Group 14 element compounds such as silicon oxide (silica, silica gel), graphite, carbon, graphite, and glass; and fine particles of natural minerals such as karnalite, kainite, mica, and byrrosite. There are no particular limitations on the average particle size of the inorganic fine particles, but it is preferably 0.01 to 3 μm.

[0052] The content of the lubricant in the resin composition relative to 100 parts by mass of the 3-methyl-1-butene polymer can be determined appropriately and may be, for example, 0.001 to 5 parts by mass or 0.005 to 3 parts by mass.

[0053] <Other Resins> The resin composition may or may not contain a resin other than the 3-methyl-1-butene polymer. In order to improve the dispersibility of additives containing polar groups, the resin composition may contain other resins other than the 3-methyl-1-butene polymer, such as a vinyl acetate-ethylene copolymer or a modified polyolefin obtained by partially oxidizing a polyolefin and / or modifying it with a reactive functional group such as maleic acid. Examples of polyolefins constituting the modified polyolefin modified with a reactive functional group include polyethylene, polypropylene, and polyolefins having a structural unit of an α-olefin having 3 to 20 carbon atoms. Examples of α-olefins having 3 to 20 carbon atoms include those described above in the <3-methyl-1-butene polymer> section. These may be homopolymers or copolymers. Furthermore, these polyolefins may be high-density or low-density and may be polymerized using at least one catalyst selected from the group consisting of a Ziegler-Natta catalyst and a metallocene catalyst. Among these, the resin other than the 3-methyl-1-butene polymer is preferably at least one selected from the group consisting of polyethylene or polypropylene, more preferably at least one selected from the group consisting of modified polyethylene or modified polypropylene, more preferably at least one selected from the group consisting of modified polyethylene or modified polypropylene in which polyolefin is partially oxidized and / or modified with a reactive functional group such as maleic acid, and even more preferably maleic anhydride-modified polypropylene.

[0054] From the viewpoint of further exerting the effects of the present invention, the content of the vinyl acetate-ethylene copolymer and the modified polyolefin obtained by partially oxidizing a polyolefin and / or modifying a polyolefin with a reactive functional group such as maleic acid in the resin composition is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the 3-methyl-1-butene polymer.

[0055] Examples of resins other than vinyl acetate-ethylene copolymers and modified polyolefins in which polyolefins are partially oxidized and / or modified with reactive functional groups such as maleic acid include polyolefins such as low-density polyethylene, high-density polyethylene, linear low-density polyethylene, very low-density polyethylene, polypropylene, syndiotactic polypropylene, polybutene, and polypentene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 6 and nylon 66; ethylene-ethyl acrylate copolymers, polystyrene, syndiotactic polystyrene, polyphenylene sulfide, polyphenylene ether, polycarbonate, and thermoplastic elastomers. Examples of thermoplastic elastomers include random or block copolymers of aromatic vinyl monomers and conjugated diene monomers, such as styrene-butadiene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene block copolymers, styrene-isoprene-styrene block copolymers, and styrene-butadiene random copolymers; polyisoprene rubber; polyolefin rubbers, such as ethylene-propylene copolymers, ethylene-α-olefin copolymers, and propylene-α-olefin copolymers; diene copolymers, such as ethylene-propylene-diene copolymers, α-olefin-diene copolymers, diene copolymers, isobutylene-isoprene copolymers, and isobutylene-diene copolymers; norbornene rubbery polymers, such as copolymers of norbornene monomers and ethylene or α-olefins, terpolymers of norbornene monomers, ethylene and α-olefins, and ring-opening polymers of norbornene monomers, and hydrogenated versions of these.

[0056] In order to further improve the flexibility, bendability, and impact resistance of the insulating film for a motor, the resin composition may contain a thermoplastic elastomer, which can prevent the insulating film for a motor from cracking due to strain or impact.

[0057] From the viewpoint of impact resistance, the thermoplastic elastomer preferably has a glass transition temperature (Tg) of 40°C or lower. Some block copolymers have two or more Tg points, but they can be preferably used as long as one of the Tg points is 40°C or lower. The number-average molecular weight is preferably 10,000 or higher, more preferably 20,000 or higher, even more preferably 30,000 or higher, and preferably 200,000 or lower. A number-average molecular weight of 10,000 or higher provides superior mechanical properties, while a number-average molecular weight of 200,000 or lower facilitates production. From the viewpoint of compatibility with the 3-methyl-1-butene polymer, non-polar elastomers, i.e., those composed only of carbon and hydrogen, are preferred.

[0058] From the viewpoint of obtaining an insulating film for a motor having a low relative dielectric constant and a low dielectric loss tangent, it is preferable that the resin composition has a reduced amount of metal elements. Therefore, from the viewpoint of easily reducing the amount of metal elements, the thermoplastic elastomer is preferably a copolymer of an aromatic vinyl monomer and a conjugated diene monomer, and more preferably a block copolymer thereof. Furthermore, from the viewpoint of improving weather resistance, a hydrogenated product thereof is even more preferable.

[0059] The content of the resin other than the thermoplastic elastomer, vinyl acetate-ethylene copolymer, and modified polyolefin obtained by partially oxidizing polyolefin and / or modifying with a reactive functional group such as maleic acid in the resin composition is preferably 1 to 100 parts by mass, more preferably 2 to 50 parts by mass, and even more preferably 3 to 30 parts by mass, per 100 parts by mass of the 3-methyl-1-butene polymer. When the content is within this range, the excellent physical properties of the 3-methyl-1-butene polymer, such as withstand voltage, heat resistance, and chemical resistance, are likely to be exhibited.

[0060] <Melting Point of Resin Composition> The melting point of the resin composition of this embodiment is preferably 260 to 310°C. When the melting point of the resin composition is within the above range, molding can be facilitated and reflow heat resistance can be further improved. The melting point of the resin composition refers to the peak temperature when measured using a method similar to that used to measure the melting point of a 3-methyl-1-butene polymer. Specifically, it can be measured using the method for measuring the melting point of a 3-methyl-1-butene polymer described in the Examples. From the viewpoint of balancing production efficiency and reflow heat resistance, the melting point of the resin composition is preferably 270 to 305°C, more preferably 280 to 305°C, and even more preferably 280 to 300°C. The melting point of the resin composition of this embodiment is almost the same as that of the 3-methyl-1-butene polymer. Therefore, in this specification, the melting point of the 3-methyl-1-butene polymer can be considered to be the melting point of the resin composition.

[0061] <Method for Producing Resin Composition> The method for producing the resin composition of this embodiment is not particularly limited as long as it can produce a resin composition containing a 3-methyl-1-butene polymer. More specifically, the method for producing the resin composition includes a step of obtaining a 3-methyl-1-butene polymer and a step of obtaining a resin composition. Details of each step can be found in the sections [Step of Obtaining a 3-methyl-1-butene Polymer] and [Step of Obtaining a Resin Composition] described below.

[0062] <Dielectric Loss Tangent of Insulating Film for Motors> The dielectric loss tangent of the insulating film for motors of this embodiment refers to the dielectric loss tangent measured at a specific frequency, specifically, the dielectric loss tangent measured at a frequency of 1 kHz to 200 GHz. From the viewpoint of economic efficiency, the dielectric loss tangent at 1 kHz to 200 GHz is preferably 0.00010 or more, more preferably 0.00013 or more, and even more preferably 0.00015 or more. From the viewpoint of reducing transmission loss, the dielectric loss tangent is preferably 0.00180 or less, more preferably 0.00140 or less, even more preferably 0.00100 or less, still more preferably 0.00080 or less, and even more preferably 0.00050 or less. That is, the dielectric loss tangent at 1 kHz to 200 GHz is preferably 0.00010 to 0.00180, more preferably 0.00010 to 0.00140, even more preferably 0.00010 to 0.00100, still more preferably 0.00013 to 0.00080, and even more preferably 0.00015 to 0.00050. The dielectric loss tangent at 1 kHz to 200 GHz of an insulating film for motors refers to a value measured by a common method such as a capacitance method, a resonance method, or a frequency variation method, and can be measured specifically by the method described in the Examples. When the measurement frequency is 1 kHz to 1 GHz, measurement is preferably performed by the capacitance method. When the measurement frequency is greater than 1 GHz and up to 200 GHz, measurement is preferably performed by the resonance method or the frequency variation method, and more preferably by the frequency variation method. In one aspect, the insulating film for a motor of this embodiment has a dielectric dissipation factor at a frequency of 1 kHz, measured by a capacitance method, of preferably 0.00010 to 0.00180, more preferably 0.00010 to 0.00140, even more preferably 0.00010 to 0.00100, still more preferably 0.00013 to 0.00080, and even more preferably 0.00015 to 0.00050. In one aspect, the insulating film for a motor of this embodiment has a dielectric dissipation factor at a frequency of 1 MHz, measured by a capacitance method, of 0.00010 to 0.00180, more preferably 0.00010 to 0.00140, even more preferably 0.00010 to 0.00100, still more preferably 0.00013 to 0.00080, and even more preferably 0.00015 to 0.00050.

[0063] <Dielectric Constant of Insulating Film for Motors> The dielectric constant of the insulating film for motors of this embodiment refers to the dielectric constant measured at a specific frequency, specifically, the dielectric constant measured at a frequency of 1 kHz to 200 GHz. From the viewpoint of economy, the dielectric constant at 1 kHz to 200 GHz is preferably 0.5 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. From the viewpoint of reducing transmission loss, the dielectric constant is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.5 or less, even more preferably 3.0 or less, and even more preferably 2.5 or less. That is, the dielectric constant at 1 kHz to 200 GHz is preferably 0.5 to 5.0, more preferably 1.5 to 4.0, even more preferably 2.0 to 3.5, even more preferably 2.0 to 3.0, and even more preferably 2.0 to 2.5. The dielectric constant of the insulating film for motors at 1 kHz to 200 GHz refers to a value measured by a common technique such as a capacitance method, a resonance method, or a frequency variation method. Specifically, it can be measured by the method described in the Examples. When the measurement frequency is 1 kHz to 1 GHz, measurement is preferably performed by the capacitance method. When the measurement frequency is greater than 1 GHz and up to 200 GHz, measurement is preferably performed by the resonance method or the frequency variation method, and more preferably the frequency variation method. In one aspect, the insulating film for motors of this embodiment has a dielectric constant at 1 kHz measured by the capacitance method of preferably 0.5 to 5.0, more preferably 1.5 to 4.0, even more preferably 2.0 to 3.5, still more preferably 2.0 to 3.0, and even more preferably 2.0 to 2.5. In one aspect, the insulating film for a motor of the present embodiment has a relative dielectric constant at 1 MHz measured by a capacitance method of preferably 0.5 to 5.0, more preferably 1.5 to 4.0, even more preferably 2.0 to 3.5, still more preferably 2.0 to 3.0, and still more preferably 2.0 to 2.5.

[0064] <Comparative Tracking Index of Insulating Film for Motors> From the viewpoint of voltage resistance, the comparative tracking index of the insulator for motors of this embodiment is preferably 600 V or more, more preferably 700 V or more, and even more preferably 800 V or more. Although a higher upper limit is preferable, it may be, for example, 4.5 kV or less, 3.5 kV or less, or 2.5 kV or less. That is, it may be 600 V to 4.5 kV, 700 V to 3.5 kV, or even more preferably 800 V to 2.5 kV. When the comparative tracking index is 600 V or more, it is possible to suppress ignition that occurs when a high voltage is applied. Methods for measuring tracking resistance (comparative tracking index) include the comparative tracking index test (CTI) based on IEC 60112:2020, JIS C 2134:2007, ASTM D 3638, and UL 746A, and the inclined-plane tracking test (IPT) based on IEC 60587:2007, JIS C2136:2004, and ASTM D2303. The upper limit of the CTI test voltage is specified as 600 V, and the lower limit of the IPT test voltage is specified as 1 kV (1000 V). In other words, there is no clear provision for measuring the comparative tracking index when the test voltage is greater than 600 V and less than 1000 V. Therefore, the comparative tracking index in this specification means a value obtained by a comparative tracking index test (CTI) measured in accordance with JIS C 2134:2007 with an upper limit of the test voltage being 900 V. Specifically, it can be measured by the method described in the examples.

[0065] <Dielectric Breakdown Strength of Motor Insulating Film> From the viewpoint of voltage resistance, the dielectric breakdown strength of the motor insulating film of this embodiment is preferably 50 kV / mm or more per unit thickness, more preferably 100 kV / mm or more, and even more preferably 150 kV / mm or more. While a higher upper limit is preferable, it may be, for example, 1000 kV / mm or less, 500 kV / mm or less, or 100 kV / mm or less. That is, it may be 50 to 1000 kV / mm, 100 to 500 kV / mm, or 150 to 100 kV / mm. A dielectric breakdown strength of 50 kV / mm or more provides superior insulation even when a high voltage is applied. The dielectric breakdown strength of the motor insulating film refers to a value measured in accordance with IEC 60243-1:2013, and specifically can be measured by the method described in the examples.

[0066] <Thickness of Motor Insulating Film> From the viewpoint of insulation properties, the thickness of the motor insulating film of this embodiment is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 120 μm or more, and from the viewpoint of suppressing a decrease in motor output, it is preferably 1000 μm or less, more preferably 700 μm or less, and even more preferably 400 μm or less. That is, the thickness of the motor insulating film is preferably 50 to 1000 μm, more preferably 100 to 700 μm, and even more preferably 120 to 400 μm.

[0067] <Water Absorption Rate of Motor Insulating Film> The water absorption rate of the motor insulating film of this embodiment is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and even more preferably 0.1% by mass or less. If the water absorption rate of the motor insulating film is within the above range, the occurrence of blisters during reflow soldering can be further suppressed. In addition, storage management before reflow soldering is also facilitated. The water absorption rate of the motor insulating film refers to a value measured in accordance with JIS K 7209:2000 Method A, and specifically can be measured by the method described in the examples.

[0068] <Method for Producing Insulating Film for Motors> The method for producing an insulating film for a motor according to this embodiment is not particularly limited as long as it is a method for producing the insulating film for a motor described above. From the viewpoint of obtaining an insulating film for a motor that has a low relative dielectric constant and a low dielectric loss tangent, as well as excellent voltage resistance and heat resistance, the method for producing an insulating film for a motor preferably includes the steps of obtaining a 3-methyl-1-butene polymer and forming the resin composition to obtain the insulating film for a motor. Furthermore, when the resin composition is obtained by blending other components such as additives in addition to the 3-methyl-1-butene polymer, it is preferable to include the step of obtaining a resin composition described below. In other words, the method for producing an insulating film for a motor more preferably includes the steps of obtaining a 3-methyl-1-butene polymer, obtaining a resin composition, and forming the resin composition to obtain the insulating film for a motor.

[0069] [Step of Obtaining a 3-methyl-1-butene Polymer] In this embodiment, the step of obtaining a 3-methyl-1-butene polymer is not particularly limited as long as it is a step that allows the production of a 3-methyl-1-butene polymer. The method of obtaining a 3-methyl-1-butene polymer is not particularly limited, and the polymer can be produced using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. More specifically, the step of obtaining a 3-methyl-1-butene polymer is a step of preparing a raw material containing 3-methyl-1-butene and polymerizing this raw material to obtain a 3-methyl-1-butene polymer. A method of obtaining a 3-methyl-1-butene polymer, for example, as described in JP-A-61-103910, involves homopolymerizing 3-methyl-1-butene in the presence of a catalyst or copolymerizing 3-methyl-1-butene with the above-mentioned α-olefin to obtain a powder. In the case of homopolymerization, the raw material contains at least 3-methyl-1-butene and may further contain a catalyst. In the case of copolymerization, the raw materials contain at least 3-methyl-1-butene and ethylene or the above-mentioned α-olefin, and may further contain a catalyst. The stereoregularity of the 3-methyl-1-butene polymer may be isotactic or syndiotactic.

[0070] [Step of Obtaining Resin Composition] The step of obtaining a resin composition is a step of blending and mixing other components such as additives in addition to the 3-methyl-1-butene polymer to obtain a resin composition. Specifically, this is a step of obtaining a resin composition containing a 3-methyl-1-butene polymer and other components. The resin composition is obtained by blending the 3-methyl-1-butene polymer with the other components. The blending method is not particularly limited, and a method of melt-kneading using a twin-screw kneading extruder can be used. Furthermore, the raw materials may be dry-blended before melt-kneading. Note that when no other components are blended in addition to the 3-methyl-1-butene polymer, the resin composition consists of the 3-methyl-1-butene polymer, and there is no need to go through the step of obtaining a resin composition. Examples of the additives include those similar to those described in the above [Resin Composition], such as alkyl radical scavengers, antioxidants, antacids, fillers, light stabilizers, antistatic agents, flame retardants, pigments, polymerization inhibitors, heavy metal deactivators, ultraviolet absorbers, nucleating agents, clarifying agents, lubricants, fluorescent brighteners, rust inhibitors, and sliding agents.

[0071] <Melt-Kneading Conditions> The melt-kneading conditions are not particularly limited, but it is preferable to perform melt-kneading by injecting an inert gas into the melt-kneader or by degassing the inside of the melt-kneader under reduced pressure. In order to suppress deterioration of the physical properties of the resin composition due to oxygen and produce an insulating film for a motor with better mechanical properties, it is preferable to perform melt-kneading in an inert atmosphere or a low-oxygen state. Here, in this embodiment, the "low-oxygen state" refers to a state in which the oxygen concentration is lowered by degassing the inside of the melt-kneader under reduced pressure compared to before degassing. Alternatively, it refers to a state in which the oxygen concentration is lowered by injecting an inert gas such as nitrogen gas compared to before the injection. In the "low-oxygen state," the oxygen concentration inside the melt-kneader is preferably 5% or less, more preferably 2% or less, and even more preferably 1% or less. The oxygen concentration is measured using an oxygen concentration meter such as a diaphragm-type galvanic oxygen meter.

[0072] The method of melt-kneading by injecting an inert gas into the melt kneader may involve, for example, introducing each component into the melt kneader while injecting the inert gas, or introducing each component into the melt kneader and then injecting the inert gas to perform melt kneading. Furthermore, the inert gas may be continuously injected into the melt kneader during melt kneading. The inert gas may be injected according to the equipment of each melt kneader. For example, the inert gas may be injected from a gas supply section such as an inert gas provided in the melt kneader, from a supply section for each component provided in the melt kneader, or from a gas vent provided in the melt kneader. There are no limitations on the injection method as long as the inert gas can be injected into the entire area from the inert gas supply section to the heating section where melt kneading is performed, thereby enabling melt kneading. Examples of inert gases include nitrogen gas, helium gas, neon gas, argon gas, krypton gas, and carbon dioxide gas. Nitrogen gas is preferred from the viewpoints of availability and versatility.

[0073] The method of degassing the inside of the melt kneader under reduced pressure to melt and knead may be, for example, to add each component to the inside of the melt kneader, and then degas the inside of the melt kneader under reduced pressure to perform melt kneading. Moreover, during melt kneading, degassing the inside of the melt kneader under reduced pressure may be performed intermittently or continuously. The method of degassing the inside of the melt kneader under reduced pressure can be performed depending on the equipment provided in each melt kneader, and may be performed, for example, through a vacuum vent. When degassing under reduced pressure, the inside of the melt kneader can be placed in a vacuum state of, for example, 0.1 kPa or more and 50 kPa or less.

[0074] The melt kneader may be a single-screw extruder, a multi-screw extruder, a kneader, a Banbury mixer, or the like, which is equipped with equipment capable of melt-kneading by injecting an inert gas into the inside of the melt kneader, or equipment capable of melt-kneading by degassing the inside of the melt kneader under reduced pressure.

[0075] The melt-kneading temperature is preferably 300 to 380°C. When the melt-kneading temperature is 300°C or higher, the 3-methyl-1-butene polymer can be sufficiently melted, and additives and the like can be easily dispersed. When the melt-kneading temperature is 380°C or lower, thermal decomposition of the 3-methyl-1-butene polymer and additives can be suppressed. From the viewpoint of sufficiently dispersing the additives throughout the 3-methyl-1-butene polymer, the melt-kneading temperature is more preferably 300°C or higher, and even more preferably 310°C or higher. Furthermore, from the viewpoint of suppressing significant decomposition of the raw materials, the melt-kneading temperature is more preferably 380°C or lower, and even more preferably 360°C or lower.

[0076] The melt-kneading time can be adjusted depending on the size of the kneading apparatus, etc. For example, it may be 1 to 15 minutes, but is not limited to this numerical range of the melt-kneading time. In this embodiment, the "melt-kneading time" refers to the time during which the mixer is rotating in a batch-type kneader, and refers to the residence time of the raw materials in the apparatus in the case of a continuous extrusion-type kneader.

[0077] The rotation speed of the mixer during melt-kneading may be 80 rpm or more or 100 rpm or more, and may be 300 rpm or less or 250 rpm or less. After melt-kneading, the resin composition is removed from the melt-kneader and cooled.

[0078] [Step of Obtaining an Insulating Film for a Motor] In this embodiment, the step of obtaining an insulating film for a motor is a step of obtaining an insulating film for a motor by molding a resin composition. The molding method is not particularly limited, and a method suitable for the application may be used. The resin composition of this embodiment is thermoplastic and can be melt-molded. Therefore, injection molding, extrusion molding, pressure molding, hot press molding, etc. can be used. Among these, extrusion molding is preferred from the viewpoints of ease of manufacturing and obtaining molded products with excellent dimensional accuracy.

[0079] <Uses of Motor Insulating Film> The motor insulating film can be suitably used as a motor insulating film for home appliances, audio equipment, IT equipment, communication equipment, office automation equipment, medical equipment, healthcare equipment, business equipment, industrial equipment, and transportation equipment such as automobiles, railways, and ships. Among these, the motor insulating film is preferably used as an in-vehicle motor insulating film, more preferably as a motor insulating film for electric vehicles. The motor insulating film can be suitably used for interphase insulating paper that provides insulation between coil phases, insulators disposed in slots, i.e., slot paper, and wedge paper that seals the slot paper and slot groove openings from the inside. By incorporating the motor insulating film, the interphase insulating paper, slot paper, and wedge paper have a low relative permittivity and low dielectric loss tangent, as well as excellent voltage resistance and heat resistance. The thickness and shape of the motor insulating film can be appropriately set depending on the application.

[0080] When the insulating film for a motor is used as an insulator in a slot, i.e., as slot paper, the insulating film for a motor may have folded and / or bent portions formed in accordance with the shape of the slot. For example, the cross-sectional shape of the insulating film for a motor may be an open polygonal cross-section, a substantially U-shaped cross-section, a substantially V-shaped cross-section, or a combination thereof. Alternatively, the polygonal cross-section may have a shape with substantially curved corners.

[0081] The motor insulating film may be disposed independently in a plurality of slots in the motor stator, or may be disposed continuously (for example, in a zigzag pattern) across a plurality of slots.

[0082] When a folding portion is formed in the insulating film for a motor, the insulating film for a motor may have a folding portion formed at an angle of 50 to 150°, or may have a folding portion formed at an angle of 60 to 140°. When the insulating film for a motor has multiple folding portions, these angles may be the same or different from each other.

[0083] When a bent portion is formed in an insulating film for a motor, the insulating film for a motor may have a bent portion with a curvature radius of 1 to 100 mm in part, or a folded portion with a curvature radius of 10 to 80 mm in part. When an insulating film for a motor has multiple bent portions, the radii of curvature may be the same or different from one another.

[0084] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0085] <Measurement and Evaluation Methods> Various physical properties were measured or evaluated by the following methods.

[0086] [Content of structural units derived from comonomers] The content of structural units derived from 1-decene (comonomer), an α-olefin other than 3-methyl-1-butene, in the 3-methyl-1-butene copolymers obtained in Production Examples 1 and 2 was determined by IR measurement using an FT-IR analyzer (manufactured by Ailent Technologies, device name "Cary 600 series FTIR spectrometer") by the ATR method, as follows: Deformation vibration derived from the main chain methylene group of 3-methyl-1-butene homopolymer: 1,461 cm －１ and the bending vibration of 727 cm originating from the side chain methylene group of the α-olefin homopolymer. －１ A calibration curve was created from the ratio of the peak area of ​​each of the 3-methyl-1-butene copolymers obtained in Production Examples 1 and 2 to the peak area of ​​each of the 3-methyl-1-butene copolymers, and the proportion of each polymer added. Next, the above-mentioned IR measurement was performed on each of the 3-methyl-1-butene copolymers obtained in Production Examples 1 and 2, and the obtained measured values ​​(peak area ratios) were inserted into the above-mentioned calibration curve to determine the content of structural units derived from α-olefins other than 3-methyl-1-butene (1-decene).

[0087] [Melting Point] Using a differential scanning calorimeter ("DSC25" manufactured by TA Instruments), the polymers (3-methyl-1-butene polymers) obtained in Production Examples 1 to 3 were heated from 30° C. to 320° C. at a rate of 10° C. / min under a nitrogen flow rate (100 mL / min), held at 320° C. for 5 minutes, and then cooled to −70° C. at a rate of 10° C. / min. After holding at −70° C. for 5 minutes, the polymers were heated to 320° C. at a rate of 10° C. / min, and the peak temperature of the endothermic peak accompanying melting was measured, and this temperature was taken as the melting point.

[0088] [Melt Viscosity] The melt viscosity (Pa·s) of the polymers (3-methyl-1-butene polymers) obtained in Production Examples 1 to 3 was measured using a capillary rheometer ("Capillography 1C" manufactured by Toyo Seiki Seisaku-sho, Ltd.) at a barrel temperature of 320°C and a shear rate of 1220 sec. －１ The measurement was carried out under the following conditions: (capillary: inner diameter 1.0 mm x length 10 mm, extrusion speed 10 mm / min).

[0089] [Mechanical Strength] Test specimens (length: 150 mm, width: 25 mm, thickness: 0.5 mm) were prepared by cutting out each of the motor insulating films obtained in Examples 1 to 5. The test specimens were stored at 23°C and 49% humidity for at least 24 hours. The yield stress (MPa) of the test specimens after storage was then measured using a universal material testing machine "INSTRON 5900R-5666" (manufactured by Instron Corporation) at 23°C, 49% humidity, and a tensile speed of 100 mm / min in accordance with JIS K 7161-1:2014. Measurements were performed five times, and the average value was used and evaluated according to the following criteria. A yield stress of 27 MPa or greater was assigned an "A," and a yield stress of less than 27 MPa was assigned a "B."

[0090] [Specific Gravity] Test specimens (length: 20 mm, width: 20 mm, thickness: 0.2 mm) were prepared by cutting out each of the insulating films for motors obtained in Examples 1 to 5 and Comparative Examples 1 and 2. Using the test specimens, specific gravity was measured in accordance with Method A of JIS K 7112:1999.

[0091] [Water Absorption Rate] Test pieces (length: 20 mm, width: 20 mm, thickness: 0.2 mm) were prepared by cutting out each of the insulating films for motors obtained in Examples 1 to 5 and Comparative Examples 1 and 2. Using the test pieces, the water absorption rate was measured in accordance with Method A of JIS K 7209:2000.

[0092] [Dielectric Constant and Dielectric Loss Tangent] Test specimens (length: 60 mm, width: 60 mm, thickness: 0.2 mm) were prepared by cutting out each of the insulating films for motors obtained in Examples 1 to 5 and Comparative Examples 1 and 2. Using the test specimens and a precision LCR meter "Keysight E6980A" (manufactured by Agilent Technologies), the dielectric constant and dielectric loss tangent were measured at measurement frequencies of 1 kHz and 1 MHz by the capacitance method in accordance with JIS C 2138:2007.

[0093] [Comparative Tracking Index] The motor insulating films obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were laminated onto a film cut to a predetermined size to prepare test pieces (length: 20 mm, width: 20 mm, thickness: 3 mm). Using the test pieces and a TRACKING RESISTANCE TESTER (manufactured by Nikka Techno Service Co., Ltd.), the comparative tracking index was measured in accordance with JIS C 2134:2007. Specifically, measurement solution A (deionized water containing anhydrous ammonium chloride (NH ) of analytical reagent grade with a purity of 99.8% or higher) was added. ４ Using a test piece (prepared by dissolving approximately 0.1 mass % of HCl in the test piece and adjusting the resistivity at 23°C ± 1°C to 3.95 Ωm ± 0.05 Ωm), the voltage was varied from 400 to 900 V, and the maximum voltage at which breakdown did not occur (comparative tracking index) was measured. The tracking resistance was evaluated from the obtained comparative tracking index according to the following criteria. A comparative tracking index of 800 V or more indicates good tracking resistance. A: Comparative tracking index of 800 V or more B: Comparative tracking index of 600 V or more but less than 800 V C: The maximum voltage at which breakdown did not occur was less than 600 V

[0094] [Dielectric Breakdown Strength] Test specimens (length: 50 mm, width: 50 mm, thickness: 0.2 mm) were prepared by cutting out each of the motor insulating films obtained in Examples 1 to 5 and Comparative Examples 1 and 2. Using the test specimens and a dielectric breakdown tester "YST-243-100RHO" (manufactured by Yamayo Test Instruments, Inc.), the dielectric breakdown strength in the thickness direction of the test specimens was measured in accordance with JIS C2110:2016. Specifically, in a test tank filled with silicone oil, the test specimens were fixed between a high-voltage electrode (a 20 mm diameter bulb) and a low-voltage electrode (a 20 mm diameter bulb), and the dielectric breakdown strength was measured by applying a 50 Hz AC voltage at 150°C at a voltage rise rate of 3 kV / s. The obtained dielectric breakdown strength values ​​were evaluated according to the following criteria. Note that a dielectric breakdown strength of 150 kV / mm or more indicates good voltage resistance. A: Dielectric breakdown strength is 150 kV / mm or more B: Dielectric breakdown strength is less than 150 kV / mm C: Conductive

[0095] [Catalyst Preparation] Preparation of Titanium Catalyst Component 47.6 g (500 mmol) of anhydrous magnesium chloride, 250 mL of decane, and 234 mL (1.5 mol) of 2-ethylhexyl alcohol were heated at 130°C for 2 hours to form a homogeneous solution. The resulting homogeneous solution was cooled to room temperature (23°C) and then added dropwise over 1 hour to 2 L (18 mol) of titanium tetrachloride maintained at -20°C. After the dropwise addition was completed, the temperature of the mixture was raised to 90°C over 2 hours. Upon reaching 90°C, 11.4 mL (80 mmol) of ethyl benzoate was added and the mixture was maintained at the same temperature for 2 hours with stirring. After the 2-hour reaction, the mixture was allowed to stand and the supernatant was removed. Decane and hexane were added, and the solid component was washed three times. After that, it was resuspended in 2 L of titanium tetrachloride and again heated at 90°C for 2 hours. After the reaction was complete, the mixture was again left to stand using decane and hexane, and the supernatant was repeatedly removed, followed by thorough washing until no free titanium compound was detected in the washings. The resulting suspension was dried under reduced pressure at room temperature for 6 hours to obtain a titanium catalyst component. The composition of the resulting titanium catalyst component was 4.0% by mass of titanium, 56.0% by mass of chlorine, 17.0% by mass of magnesium, 10.4% by mass of ethyl benzoate, and 12.6% by mass of a hydrocarbon solvent consisting of decane and hexane.

[0096] [Production Example 1] Production of Copolymer (A) 8.0 kg of 3-methyl-1-butene, 0.6 kg of 1-decene, 50 g of triethylaluminum diluted with hexane to a concentration of 1 mol / L, and 4 g of the titanium catalyst component produced in the above [Catalyst Preparation] were added to a 20 L stainless steel autoclave, and a polymerization reaction was carried out at 70 °C for 4 hours. During the polymerization reaction, hydrogen was continuously fed at a rate of 40 mL / min. After 4 hours, 200 g of 3-methyl-1-butanol was injected to stop the reaction and expel excess unreacted monomer. Next, 2 kg of normal heptane was introduced, and the mixture was stirred at 60 °C for 30 minutes, after which the solids were filtered off using a pressure filter. This procedure was repeated twice, and then the solvent was changed from 2 kg of normal heptane to 3 kg of 2-propanol, and the same procedure was repeated twice. 7.7 kg of the obtained crude polymer was placed in a 50 L vessel equipped with a stirrer, followed by the addition of 8 kg of 1 mol / L hydrochloric acid and 16 kg of 2-propanol, followed by stirring for 1 hour. This suspension was filtered by vacuum filtration and washed with 10 kg of 2-propanol. This crude polymer was placed in a 50 L vessel equipped with a stirrer, followed by the addition of 20 kg of 2-propanol, followed by stirring for 1 hour. This suspension was filtered by vacuum filtration and washed with 10 kg of 2-propanol. The washed polymer obtained was dried under reduced pressure at 80°C for 2 days to obtain 3.2 kg of copolymer (A), a copolymer of 3-methyl-1-butene and 1-decene. The above-mentioned measurements were performed on the obtained copolymer (A), and the melting point was 286°C and the melt viscosity was 104 Pa s. Furthermore, the content of structural units derived from the comonomer 1-decene in copolymer (A) was 1.1 mol%.

[0097] [Production Example 2] Production of Copolymer (B) The same procedure as in Production Example 1 was carried out, except that 0.6 kg of 1-decene was changed to 3.6 kg of 1-decene, to obtain 2.8 kg of copolymer (B), a copolymer of 3-methyl-1-butene and 1-decene. When the above-mentioned measurements were carried out on the obtained copolymer (B), it was found that the melting point was 281°C and the melt viscosity was 99 Pa s. Furthermore, the content of structural units derived from the comonomer 1-decene in copolymer (B) was 6.4 mol%.

[0098] [Production Example 3] Production of homopolymer (C) The same operation as in Production Example 1 was carried out, except that 0.6 kg of 1-decene was not added, to obtain 3.3 kg of homopolymer (C), which is a homopolymer of 3-methyl-1-butene. When the above-mentioned measurements were carried out on the obtained homopolymer (C), it was found that the melting point was 305°C and the melt viscosity was 126 Pa s.

[0099] Example 1 To 100 parts by mass of the copolymer (A) obtained in Production Example 1, 0.2 parts by mass of pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] ("AO-60", manufactured by ADEKA Corporation), 0.2 parts by mass of 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane ("PEP-36", manufactured by ADEKA Corporation), 0.1 part by mass of 2,4-di-t-amyl-6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate (Sumilizer (registered trademark) GS, manufactured by Sumitomo Chemical Co., Ltd.) and 0.25 part by mass of zinc stearate (antacid) were dry blended, and then the mixture was melt-kneaded at a cylinder temperature of 320°C using a twin-screw kneading extruder KZW15-45 (manufactured by Technovel Corporation) to obtain a pellet-shaped resin composition (M1).

[0100] The resulting pellet-like resin composition (M1) was fed to a twin-screw kneading extruder "KZW15-45" (manufactured by Technovel Corporation), melt-kneaded at a cylinder temperature of 310°C, and melt-extruded into a film from a T-die. The resulting film was then cooled and solidified on a cooling roll at 110°C to obtain an insulating film for motors (P1) with a thickness of 200 μm. The evaluation results are shown in Table 1.

[0101] Example 2 100 parts by mass of the copolymer (A) obtained in Production Example 1 was dry-blended with 0.2 parts by mass of pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] ("AO-60", manufactured by ADEKA Corporation) as a phenolic antioxidant, 0.2 parts by mass of 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane ("PEP-36", manufactured by ADEKA Corporation) as a phosphorus-based antioxidant, and 0.25 parts by mass of zinc stearate (antacid), and the mixture was melt-kneaded under a nitrogen atmosphere using a twin-screw kneading extruder "KZW15-45" (manufactured by Technovel Corporation) to obtain a pellet-shaped resin composition (M2).

[0102] The resulting pellet-like resin composition (M2) was melt-kneaded under a nitrogen atmosphere at a cylinder temperature of 310°C using a twin-screw kneading extruder "KZW15-45" (manufactured by Technovel Corporation) and melt-extruded into a film from a T-die. The resulting film was then cooled and solidified on a cooling roll at 110°C to obtain an insulating film for motors (P2) with a thickness of 200 μm. The evaluation results are shown in Table 1.

[0103] Example 3 100 parts by mass of the copolymer (A) obtained in Production Example 1 was dry-blended with 0.67 parts by mass of pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] ("AO-60", manufactured by ADEKA Corporation) as a phenolic antioxidant, 1.33 parts by mass of 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane ("PEP-36", manufactured by ADEKA Corporation) as a phosphorus-based antioxidant, and 0.25 parts by mass of zinc stearate (antacid), and the mixture was melt-kneaded under an air atmosphere using a twin-screw kneading extruder "KZW15-45" (manufactured by Technovel Corporation) to obtain a pellet-shaped resin composition (M3).

[0104] The resulting pellet-like resin composition (M3) was melt-kneaded in an air atmosphere at a cylinder temperature of 310°C using a twin-screw kneading extruder "KZW15-45" (manufactured by Technovel Corporation) and melt-extruded into a film from a T-die. The resulting film was then cooled and solidified on a cooling roll at 110°C to obtain an insulating film for motors (P3) with a thickness of 200 μm. The evaluation results are shown in Table 1.

[0105] [Example 4] A resin composition (M4) and an insulating film for a motor (P4) were obtained in the same manner as in Example 1, except that the copolymer (B) obtained in Production Example 2 was used instead of the copolymer (A) in Example 1. The evaluation results are shown in Table 1.

[0106] [Example 5] A resin composition (M5) and an insulating film for a motor (P5) were obtained in the same manner as in Example 1, except that the homopolymer (C) obtained in Production Example 3 was used instead of the copolymer (A) in Example 1. The evaluation results are shown in Table 1.

[0107]

[0108] Comparative Example 1 Evaluation was carried out in the same manner as in Example 1, except that the motor insulating film (P1) was replaced with a PEEK film "APTIV1000" (manufactured by Victrex Japan Co., Ltd., thickness 200 μm, motor insulating film (Q1)). The evaluation results are shown in Table 2.

[0109] Comparative Example 2 An insulating film for a motor (Q2) having a thickness of 200 μm was obtained in the same manner as in Example 1, except that polymethylpentene "MX002O" (manufactured by Mitsui Chemicals, Inc.) was used instead of the resin composition (M1), the cylinder temperature was set to 270° C., and cooling and solidification was performed on a cooling roll at 80° C. The evaluation results of the insulating film for a motor (Q2) obtained are shown in Table 2.

[0110]

[0111] As can be seen from a comparison of Tables 1 and 2, insulating films for motors containing resin compositions containing the 3-methyl-1-butene polymer of the present invention are lightweight, have low water absorption, low relative dielectric constants and low dielectric loss tangents, and also have excellent heat resistance due to their high voltage resistance and high melting points. In particular, their excellent heat resistance allows for miniaturization. Therefore, they are suitable for use as insulating films for motors. Furthermore, in Examples 1, 4, and 5, the mechanical properties of the insulating films are further improved by including an alkyl radical scavenger in the materials.

Claims

1. An insulating film for a motor, comprising a resin composition containing a 3-methyl-1-butene polymer.

2. 2. The insulating film for motors according to claim 1, wherein the 3-methyl-1-butene polymer is at least one selected from the group consisting of a 3-methyl-1-butene homopolymer and a copolymer of 3-methyl-1-butene with ethylene or an α-olefin, and the α-olefin is an α-olefin having 3 to 20 carbon atoms.

3. 3. The insulating film for motors according to claim 2, wherein the content of the structural units derived from ethylene or an α-olefin in the copolymer is more than 0 mol % and not more than 20 mol %.

4. The insulating film for a motor according to any one of claims 1 to 3, wherein a comparative tracking index measured in accordance with JIS C 2134:2007 is 600 V or more.

5. The insulating film for a motor according to any one of claims 1 to 3, having a thickness of 50 µm or more and 1000 µm or less.

6. 3. The insulating film for motors according to claim 2, wherein the content of the structural units derived from 3-methyl-1-butene in the copolymer is more than 50 mol % and less than 100 mol %.

7. An interphase insulating paper comprising the insulating film for a motor according to any one of claims 1 to 3 or 6.

8. A slotted paper comprising the insulating film for a motor according to any one of claims 1 to 3 or 6.

9. A wedge paper comprising the insulating film for a motor according to any one of claims 1 to 3 or 6.