Film for motor insulating paper and method for manufacturing same

Abstract

The present invention provides: a film for motor insulation paper, which is excellent in terms of mechanical properties such as bending resistance and flexibility, heat resistance such as dimensional stability, and electric characteristics such as electric insulation in a well-balanced manner; and a method for manufacturing the same.　This film for motor insulation paper is melt molded from a composition that contains a thermoplastic crystalline resin and an elastomer, has a thickness of 50 μm to 1,000 μm, has a dimensional change rate of less than 10%, has the elastomer dispersed in the crystalline resin, and has a crystallinity of 95% or less with respect to the crystallinity of the crystalline resin.　(X): The dimensional change rate (%) = (1 - (L1 / L0)) × 100 In the formula, L0 represents the length of the film in the MD direction, and L1 represents the length of the film in the MD direction after being left at a temperature of 200°C for one hour.

Description

Film for motor insulating paper and its manufacturing method

[0001] The present invention relates to a film for motor insulating paper and a method for manufacturing the same.

[0002] Engineering plastics such as polyaryletherketone and polyarylene sulfide have excellent heat resistance and mechanical properties and are widely used as molding materials in various fields.

[0003] Attempts have been made to improve the performance of engineering plastics by using resin compositions. Patent Document 1 discloses a film containing an aromatic polyether ketone resin and a fluoropolymer, the fluoropolymer forming a dispersed phase, and the aromatic polyether ketone resin having a crystallinity of less than 6%. Patent Document 2 discloses a film containing a polyaryl ether ketone and a fluoroelastomer, the fluoroelastomer forming a dispersed phase. Patent Document 3 discloses a molded article of a thermoplastic resin having a specific shear stress and a fluoroelastomer dispersed in the thermoplastic resin.

[0004] International Publication No. 2022 / 030410 International Publication No. 2017 / 188280 International Publication No. 2020 / 086218

[0005] The compositions of engineering plastics such as polyaryl ether ketone and elastomers disclosed in Patent Documents 1 to 3 are said to have improved flexibility, flex resistance, and low dielectric properties, and to have excellent impact resistance and moldability. However, in molded products such as films formed from these compositions, it is difficult to achieve a good balance between mechanical properties such as flex resistance and flexibility, heat resistance properties such as dimensional stability, and electrical properties such as electrical insulation. In particular, in the case of thin films within a certain thickness range, it is difficult to achieve a good balance of these properties, and there is still room for improvement when applying these compositions to insulating paper films that constitute insulating sheets used in rotating electrical machines such as motors and generators.

[0006] The present inventors have focused on the relationship between the crystallinity of a composition of an engineering plastic such as polyaryl ether ketone and an elastomer and the crystallinity of the engineering plastic itself that constitutes such a composition, and have found that controlling the crystallinity within a predetermined range makes it possible to obtain a film that has a well-balanced combination of mechanical properties, heat resistance, and electrical properties and is highly durable, and that such a film is useful as an insulating sheet for motors, generators, etc.

[0007] An object of the present invention is to provide a film for motor insulating paper that has a good balance of mechanical properties such as bending resistance and flexibility, heat resistance such as dimensional stability, and electrical properties such as electrical insulation, and a method for producing the same. Another object of the present invention is to provide motor insulating paper that includes such a film for motor insulating paper.

[0008] The present invention has the following aspects: [1] A film for motor insulating paper, which is melt-molded from a composition containing a thermoplastic crystalline resin and an elastomer, has a thickness of 50 to 1000 μm, and has a dimensional change rate calculated by the following formula (X) of less than 10%, in which the elastomer is dispersed in the crystalline resin, and the crystallinity of the film is 95% or less relative to the crystallinity of the crystalline resin. Dimensional change rate (%) = (1 - (L １ / L ０ ))×100...(X) In formula (X), L ０ is the length of the film for motor insulating paper in the MD direction, and L １is the length in the machine direction of the film for motor insulating paper after the film for motor insulating paper has been left at 200°C for 1 hour. [2] The film for motor insulating paper according to [1], wherein the crystalline resin is at least one selected from the group consisting of polyarylsulfone, polyarylene sulfide, polyethersulfone, polyaryletherketone, and liquid crystal polyester. [3] The film for motor insulating paper according to [1] or [2], wherein the elastomer is a fluoroelastomer. [4] The film for motor insulating paper according to any of [1] to [3], wherein the content of the elastomer relative to the total of the crystalline resin and the elastomer is 1% by volume or more and 50% by volume or less. [5] The film for motor insulating paper according to any of [1] to [4], wherein the tensile modulus of elasticity is 3600 MPa or less. [6] The film for motor insulating paper according to any of [1] to [5], wherein the crystallinity of the crystalline resin is 10% by volume or more and 70% or less. [7] A film for motor insulating paper according to any one of [1] to [6], having a relative dielectric constant of less than 3.5. [8] A film for motor insulating paper according to any one of [1] to [7], having a thickness of 500 μm or less. [9] A film for motor insulating paper according to any one of [1] to [8], having an average dispersed particle size of the elastomer of less than 5.0 μm.

[10] A method for producing a film for motor insulating paper, comprising melt-molding a composition containing a thermoplastic crystalline resin and an elastomer, followed by cooling at 180°C or higher, the film having a thickness of 50 to 1000 μm, a dimensional change rate calculated by the following formula (X) of less than 10%, the elastomer being dispersed in the crystalline resin, and a crystallinity of 95% or less relative to the crystallinity of the crystalline resin. Dimensional change rate (%) = (1 - (L １ / L ０ ))×100...(X) In formula (X), L ０ is the length of the film for motor insulating paper in the MD direction, and L １is the length in the machine direction of the film for motor insulating paper after the film for motor insulating paper has been left at 200°C for 1 hour.

[11] The manufacturing method of

[10] , in which the cooling is performed from both sides of the melt-molded film.

[12] The manufacturing method of

[10] or

[11] , in which the crystalline resin is at least one selected from the group consisting of polyarylsulfone, polyarylene sulfide, polyethersulfone, polyaryletherketone, and liquid crystal polyester.

[13] The manufacturing method of any of

[10] to

[12] , in which the elastomer is a fluoroelastomer.

[14] The manufacturing method of any of

[10] to

[13] , in which the content of the elastomer relative to the total content of the crystalline resin and the elastomer is 1% by volume or more and 50% by volume or less.

[15] Motor insulating paper comprising the film for motor insulating paper of any of [1] to [9].

[0009] The present invention can provide a film for motor insulating paper that has a good balance of mechanical properties such as bending resistance and flexibility, heat resistance such as dimensional stability, and electrical properties such as electrical insulation, a method for producing the same, and motor insulating paper that includes the film for motor insulating paper.

[0010] The meanings of the terms are as follows. The "melting point" of a thermoplastic crystalline resin is the temperature corresponding to the maximum value of the melting peak when the temperature is increased at a rate of 10°C / min using a differential scanning calorimeter. The "melt viscosity" of a thermoplastic crystalline resin is measured at 320°C and a shear rate of 122 s using a capillograph (capillary length L: 10 mm, capillary inner diameter r: 1.0 mm, piston diameter D: 9.55 mm). －１ The "volume" of a thermoplastic crystalline resin or elastomer is calculated by multiplying the mass (g) of the crystalline resin or elastomer by its specific gravity (g / cm ３ The "specific gravity" of a thermoplastic crystalline resin or elastomer is a value measured at 23°C by the water displacement (suspension) method. The "Mooney viscosity (ML １＋１０The "temperature (temperature, 121°C)" is a value measured at 121°C in accordance with JIS K6300-1:2000 (corresponding international standards ISO 289-1:2005, ISO 289-2:1994). The "fluorine content" of a fluoroelastomer refers to the ratio of the mass of fluorine atoms to the total mass of all atoms constituting the fluoroelastomer. The fluorine content is calculated from the molar ratio of each unit in the fluoroelastomer determined by NMR measurement and total fluorine content measurement. The "end of the polymer main chain" refers to both the end of the main chain and the end of the branched chain. The "main chain" refers to the main carbon chain of a linear compound, meaning the trunk portion with the largest number of carbon atoms. The "unit" in a polymer refers to an atomic group based on a monomer formed by polymerization of that monomer. The unit may be a unit formed directly by the polymerization reaction, or a unit in which a portion of the unit is converted into a different structure by processing the polymer. Hereinafter, a unit based on monomer α will also be referred to simply as "monomer α unit." The use of "to" to indicate a range of values ​​means that the values ​​before and after "to" are included as the lower and upper limits. The ranges of values ​​disclosed in this specification can be combined in any way to create new ranges of values.

[0011] [Film for Motor Insulating Paper] An embodiment of the present invention relates to a film for motor insulating paper (hereinafter also referred to as "the film") that is melt-molded from a composition (hereinafter also referred to as "the composition") containing a thermoplastic crystalline resin (hereinafter also referred to as "crystalline resin") and an elastomer, has a thickness of 50 to 1000 μm, has a dimensional change rate calculated by the following formula (X) of less than 10%, the elastomer is dispersed in the crystalline resin, and has a crystallinity of 95% or less relative to the crystallinity of the crystalline resin. Dimensional change rate (%) = (1 - (L １ / L ０ ))×100...(X) In formula (X), L ０ is the length of the film in the MD direction, and L １ is the length in the MD direction of the film after it has been left at 200°C for 1 hour.

[0012] The present film exhibits a well-balanced and excellent combination of mechanical properties such as bending resistance and flexibility, heat resistance such as dimensional stability, and electrical properties such as electrical insulation. The reasons for this are not entirely clear, but are thought to be as follows: In a film melt-formed from a composition containing a crystalline resin and an elastomer, the elastomer likely functions as a crystal nucleating agent that increases the crystallization rate of the film, and is thought to tend to reduce the crystallinity of the melt-formed film relative to the crystallinity of the crystalline resin itself that constitutes the film. The present inventors have also found that this tendency is more likely to be manifested when such a composition is melt-formed into a film and then cooled at a high temperature of 180°C or higher. The elastomer remains dispersed in the crystalline resin, and the dispersed elastomer more easily functions as a crystal nucleating agent, which is thought to facilitate the reduction and convergence of the crystallinity of the present film relative to the crystallinity of the crystalline resin within a predetermined range. Therefore, it is believed that this film possesses a highly balanced combination of electrical properties such as electrical insulation while maintaining mechanical properties such as bending resistance and flexibility, and heat resistance such as dimensional stability, which are based on the crystalline resin.

[0013] The thickness of the present film is 50 to 1000 μm. The thickness of the present film is preferably 75 μm or more, more preferably 100 μm or more. The thickness of the present film is also preferably 500 μm or less, more preferably 200 μm or less. When the thickness of the present film is within the above range, mechanical properties such as strength and handleability are improved. Furthermore, even thin films of 200 μm or less have excellent heat resistance, electrical insulation properties, and mechanical properties, so the present film can be effectively used for motor insulating paper.

[0014] The dimensional change rate of the present film is preferably 5% or less, more preferably 2% or less. Also, the dimensional change rate of the present film is preferably 0% or more. When the dimensional change rate is within the above range, the present film has heat resistance.

[0015] The crystallinity of the present film is preferably 10% or more, more preferably 13% or more, and even more preferably 16% or more. The upper limit of the crystallinity of the present film is not particularly limited, but may be 80% or less, 70% or less, 50% or less, 40% or less, or 30% or less. When the crystallinity of the present film is within the above range, the mechanical properties and heat resistance characteristics are improved.

[0016] Furthermore, the ratio of the crystallinity of the present film to the crystallinity of the crystalline resin constituting the present film is 95% or less, preferably 90% or less, more preferably 80% or less, even more preferably 70% or less, and particularly preferably 60% or less. The ratio of the crystallinity of the present film to the crystallinity of the crystalline resin constituting the present film is preferably 10% or more. When the ratio of the crystallinity of the present film to the crystallinity of the crystalline resin constituting the present film is within the above range, the present film is likely to have a highly balanced electrical properties such as electrical insulation while maintaining mechanical properties and heat resistance such as dimensional stability. When the crystalline resin constituting the present film is polyaryl ether ketone, the ratio of the crystallinity of the present film is preferably 10 to 70%, more preferably 10 to 40%. When the crystalline resin constituting the present film is polyarylene sulfide, the ratio of the crystallinity of the present film is preferably 10 to 70%, more preferably 30 to 60%.

[0017] The tensile modulus of the present film is preferably 3600 MPa or less, and from the viewpoint of flexibility, it is more preferably 3550 MPa or less, even more preferably 3500 MPa or less, and even more preferably 3000 MPa or less. The lower limit of the tensile modulus of the present film is not particularly limited, but for example, 1500 MPa or more is preferable, and 2000 MPa or more is more preferable. Furthermore, the tensile modulus of the present film after being left at 200°C for 500 hours is preferably 1500 MPa or more, more preferably 2000 MPa or more, and even more preferably 2100 MPa or more. The upper limit of the tensile modulus of the present film after being left at 200°C for 500 hours is not particularly limited, but for example, 4000 MPa or less is preferable. When the tensile modulus of the present film after being left at 200°C for 500 hours is within the above range, it is likely to have heat resistance sufficient for practical use.

[0018] The dielectric constant of the present film is preferably less than 3.5, more preferably 2.5 or less. The dielectric constant of the present film is preferably 1 or greater. When the dielectric constant is within the above range, the present film has excellent heat resistance and oil resistance, and is likely to maintain electrical properties such as electrical insulation over a long period of time. Furthermore, in motor insulating paper using the present film, the inception voltage of partial discharge is likely to be increased, and as a result, the occurrence of partial discharge is likely to be suppressed.

[0019] The breakdown voltage of the present film at room temperature (23°C) is preferably 1500 kV or more, more preferably 1800 kV or more, even more preferably 2000 kV or more, and particularly preferably 2200 kV or more. The upper limit of the breakdown voltage of the present film at room temperature (23°C) is not particularly limited and may be, for example, 4000 kV or less. The breakdown voltage of the present film at 200°C is preferably 1200 kV or more, more preferably 1400 kV or more, even more preferably 1600 kV or more, and particularly preferably 1800 kV or more. The upper limit of the breakdown voltage of the present film at 200°C is not particularly limited and may be, for example, 4000 kV or less. Furthermore, the breakdown voltage of the present film after leaving it at 200°C for 500 hours is preferably 1200 kV or more, more preferably 1400 kV or more, even more preferably 1600 kV or more, and particularly preferably 1800 kV or more. The upper limit of the breakdown voltage of the present film after standing at 200°C for 500 hours is not particularly limited, but may be, for example, 4000 kV or less. The breakdown voltage is the voltage at which, when there are minute void-like defects in a film obtained by molding an engineering plastic, an electric field concentrates at that part, causing a discharge and a sudden current flow. A relatively higher breakdown voltage means that there are fewer minute void-like defects in the present film, and is therefore preferable.

[0020] The stress at break of the present film is preferably 30 MPa or more, more preferably 40 MPa or more, and even more preferably 50 MPa or more. The upper limit of the stress at break of the present film is not particularly limited, but is preferably, for example, 500 MPa or less. Furthermore, the stress at break of the present film after being left at 200°C for 500 hours is preferably 30 MPa or more, more preferably 40 MPa or more, and even more preferably 50 MPa or more. The upper limit of the stress at break of the present film after being left at 200°C for 500 hours is not particularly limited, but is preferably, for example, 500 MPa or less.

[0021] The elongation at break of the present film is preferably 10 to 250%, more preferably 40 to 250%, and even more preferably 50 to 250%. When the elongation at break of the present film is within the above range, processability is likely to be improved. Furthermore, the elongation at break of the present film after being left at 200°C for 500 hours is preferably 10 to 250%, more preferably 20 to 250%, and even more preferably 30 to 250%.

[0022] The crystalline resin constituting the present film is preferably at least one melt-moldable thermoplastic heat-resistant resin selected from the group consisting of polyarylsulfone, polyarylene sulfide (hereinafter also referred to as "PAS"), polyethersulfone, polyaryletherketone (hereinafter also referred to as "PAEK"), and liquid crystal polyester. From the viewpoints of mechanical properties and heat resistance, the crystalline resin is preferably at least one selected from the group consisting of PAS and PAEK. PAEK is preferred from the viewpoint of reducing microvoid defects in the present film. The crystalline resin may be used alone or in combination of two or more.

[0023] The PAS is preferably a polymer having the following unit (a) in an amount of 70 mol % or more based on all structural units: [-Ar-S-] (a)

[0024] In formula (a), Ar represents a divalent aromatic group having one or more benzene rings. When two or more benzene rings are present, they may be a group based on a condensed ring such as a naphthalene ring, and the two or more benzene rings may be bonded to a single bond, -O-, -S(=O) ２It may also be a group having a structure in which the bond is formed via -- or --C(.dbd.O)--.

[0025] The divalent aromatic group may have a substituent such as an alkyl group having 1 to 10 carbon atoms, a nitro group, a phenyl group, an alkoxy group having 1 to 10 carbon atoms, a carboxy group, or a metal carboxylate base (sodium salt, lithium salt, etc.).

[0026] In the PAS, the proportion of the unit (a) relative to all structural units is preferably 80 mol % or more, more preferably 85 mol % or more, and may be 100 mol % in terms of toughness.

[0027] The PAS may further have another unit other than the unit (a). Examples of the other unit include a polyfunctional unit having three or more bonds in which one or more -S- are further bonded to Ar in the unit (a). When the PAS has a polyfunctional unit as another unit, the PAS has a branched structure or a crosslinked structure.

[0028] As the PAS, either a linear PAS having a molecular structure that does not have a branched structure or a crosslinked structure, or a crosslinked PAS having a branched structure or a crosslinked structure can be used. From the viewpoint of easily improving the toughness of the present film, a linear PAS is preferred.

[0029] As the PAS, polyphenylene sulfide (PPS) in which Ar in the unit (a) is a phenylene group is more preferred from the viewpoints of mechanical properties and heat resistance.

[0030] As the PAEK, polyether ketone (PEK), polyether ether ketone (PEEK), and polyether ketone ketone (PEKK) are preferred, with PEEK being more preferred, from the viewpoints of excellent mechanical properties and heat resistance and reducing microvoid defects. One type of PAEK may be used alone, or two or more types may be used in combination.

[0031] The elastomer in the present invention is preferably a fluoroelastomer. A fluoroelastomer is a polymer containing units based on a fluoroolefin. A fluoroelastomer containing units based on at least one fluoroolefin selected from the group consisting of tetrafluoroethylene (hereinafter also referred to as "TFE"), hexafluoropropylene (hereinafter also referred to as "HFE"), vinylidene fluoride (hereinafter also referred to as "VdF"), vinyl fluoride (hereinafter also referred to as "VF"), and chlorotrifluoroethylene (hereinafter also referred to as "CTFE") is preferred. Furthermore, the fluoroelastomer is an elastic polymer that has no melting point and exhibits a storage modulus G' at 100°C and 50 cpm of 80 or more, as measured in accordance with ASTM D6204. One type of fluoroelastomer may be used alone, or two or more types may be used in combination.

[0032] Fluoroelastomer may be the fluoroelastomer that only consists of one or more units selected from the group consisting of TFE unit, HFP unit, VdF unit, VF unit and CTFE unit.Fluoroelastomer may also be the fluoroelastomer that comprises one or more units selected from the group consisting of TFE unit, HFP unit, VdF unit, VF unit and CTFE unit, and other monomer units other than TFE unit, HFP unit, VdF unit, VF unit and CTFE unit.

[0033] Other monomers include ethylene (hereinafter also referred to as "E"), propylene (hereinafter also referred to as "P"), perfluoro(alkyl vinyl ether) (hereinafter also referred to as "PAVE"), 1,2-difluoroethylene (hereinafter also referred to as "DiFE"), 1,1,2-trifluoroethylene (hereinafter also referred to as "TrFE"), 3,3,3-trifluoro-1-propylene (hereinafter also referred to as "TFP"), 1,3,3,3-tetrafluoropropylene, and 2,3,3,3-tetrafluoropropylene. Examples of PAVE include perfluoro(methyl vinyl ether) (hereinafter also referred to as "PMVE"), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether) (hereinafter also referred to as "PPVE"), and perfluoro(butyl vinyl ether).

[0034] The fluoroelastomer is preferably a fluoroelastomer having a saturated hydrocarbon segment. The saturated hydrocarbon segment is preferably present in the main chain of the fluoroelastomer. The saturated hydrocarbon segment may be the monomer unit itself that forms the fluoroelastomer, or may be included as part of the monomer unit that forms the fluoroelastomer. When the elastomer is such a fluoroelastomer, its function as a crystal nucleating agent is enhanced, and the above-mentioned mechanism of action is more likely to be exhibited.

[0035] Examples of fluoroelastomers having saturated hydrocarbon segments include TFE / P-containing copolymers (which means copolymers containing TFE units and P units; the same applies to the following descriptions) and HFP / VdF-containing copolymers. The total of the units connected by " / " is preferably 50 mol% or more of all units constituting the copolymer. For example, in the case of a TFE / P-containing copolymer, the total proportion of TFE units and P units is preferably 50 mol% or more of all units constituting the copolymer. The same applies to the copolymers exemplified below.

[0036] Examples of the TFE / P-containing copolymer include TFE / P (meaning a copolymer composed of TFE units and P units; the same applies to others), TFE / P / VF, TFE / P / VdF, TFE / P / E, TFE / P / TFP, TFE / P / PAVE, TFE / P / 1,3,3,3-tetrafluoropropylene, TFE / P / 2,3,3,3-tetrafluoropropylene, TFE / P / TrFE, TFE / P / DiFE, TFE / P / VdF / TFP, and TFE / P / VdF / PAVE. Examples of HFP / VdF-containing copolymers include HFP / VdF, TFE / VdF / HFP, TFE / VdF / HFP / TFP, TFE / VdF / HFP / PAVE, VdF / HFP / TFP, and VdF / HFP / PAVE. Examples of TFE / PAVE-containing copolymers include TFE / PAVE, TFE / PMVE, and TFE / PMVE / PPVE. Fluoroelastomer B also includes TFE / VdF / 2,3,3,3-tetrafluoropropylene-containing copolymers, VdF / PAVE-containing copolymers, VdF / 2,3,3,3-tetrafluoropropylene-containing copolymers, and E / HFP-containing copolymers.

[0037] As the fluoroelastomer, TFE / P-containing copolymer, HFP / VdF-containing copolymer, and TFE / PAVE-containing copolymer are preferred, with TFE / P, HFP / VdF (FKM), and TFE / PMVE / PPVE (FFKM) being more preferred, and TFE / P being even more preferred. Since the TFE / P-containing copolymer and the HFP / VdF-containing copolymer have hydrocarbon segments, they tend to have good dispersibility in crystalline resins. As a result, the above-mentioned functions are more likely to be exhibited. These polymers may contain units based on a fluoromonomer having a crosslinkable group, and the fluoroelastomer may be a crosslinked polymer.

[0038] The fluorine content of the fluoroelastomer is preferably from 50 to 74% by mass, more preferably from 55 to 70% by mass, which tends to improve the heat resistance, chemical resistance, and flexibility of the present film.

[0039] The storage modulus G' of the fluoroelastomer is preferably 80 to 800, more preferably 100 to 800, and even more preferably 120 to 600. The larger the storage modulus G', the larger the molecular weight of the fluoroelastomer and the higher the density of entanglement of molecular chains. When the storage modulus G' is within the above range, the film tends to have excellent mechanical properties. The storage modulus G' is a value measured in accordance with ASTM D6204 at 100°C and 50 cpm.

[0040] The number average molecular weight of the fluoroelastomer is preferably 10,000 to 1,500,000, more preferably 20,000 to 1,000,000, still more preferably 20,000 to 800,000, and particularly preferably 50,000 to 600,000. When the number average molecular weight of the fluoroelastomer is within the above range, the fluidity of the composition and the dispersibility of the fluoroelastomer in the composition are likely to be improved, and the flexibility and mechanical properties of the film are likely to be excellent.

[0041] Mooney viscosity of fluoroelastomer (ML １＋１０ , 121°C) is preferably 10 to 300, more preferably 20 to 280, and even more preferably 30 to 250. Mooney viscosity is a measure of molecular weight and is measured in accordance with JIS K6300-1:2000. A larger value indicates a larger molecular weight, and a smaller value indicates a smaller molecular weight. The Mooney viscosity (ML １＋１０ , 121°C) within the above range, the fluidity of the composition and the dispersibility of the fluoroelastomer in the composition are likely to be improved, and the flexibility and mechanical properties of the film are likely to be excellent.

[0042] The fluoroelastomer may be a commercially available product, or may be synthesized by emulsion polymerization, solution polymerization, suspension polymerization, bulk polymerization, or the like.

[0043] In order to improve the molding processability of the present composition, the fluoroelastomer may have a functional group at its terminal, which is preferably at least one selected from the group consisting of an iodine atom, an epoxy group, and a carboxylic acid anhydride group, and more preferably an iodine atom.

[0044] Here, "having a functional group at the end" means that the functional group is bonded to at least one of the end of the polymer main chain of the fluoroelastomer or a side group of the polymer main chain of the fluoroelastomer. From the viewpoint of molding processability, it is preferable that the functional group is bonded at least to the end of the polymer main chain of the fluoroelastomer.

[0045] When the fluoroelastomer has a functional group, the content thereof is not particularly limited. For example, when the fluoroelastomer has an iodine atom as the functional group, the content of the iodine atom as the functional group is preferably 0.01 to 5.0 mass%, more preferably 0.05 to 2.0 mass%, and even more preferably 0.05 to 1.0 mass%, based on the total mass of the fluoroelastomer.

[0046] The present film is formed from the present composition by melt molding. The content of the elastomer in the present film relative to the total of the crystalline resin and the elastomer is preferably 1% by volume or more and 50% by volume or less. This content is more preferably 5% by volume or more, even more preferably 10% by volume or more, even more preferably 15% by volume or more, particularly preferably 20% by volume or more, extremely preferably 25% by volume or more, and most preferably 30% by volume or more. This content is more preferably 45% by volume or less, even more preferably 40% by volume or less. When the content of the elastomer relative to the total of the crystalline resin and the elastomer is within the above range, the flexibility, heat resistance, and mechanical properties of the present film are likely to be improved.

[0047] The total volume ratio of the crystalline resin and elastomer to the entire composition is preferably 50 to 100% by volume, more preferably 60 to 99% by volume, and even more preferably 70 to 97% by volume. When the total volume ratio of the crystalline resin and elastomer to the entire composition is within the above range, the flexibility, heat resistance, and mechanical properties of the film based on the crystalline resin and elastomer, preferably the crystalline resin and fluoroelastomer, are easily exhibited.

[0048] In the present composition and film, an elastomer is dispersed in a crystalline resin. In the present film, the average dispersed particle size of the elastomer dispersed in the crystalline resin is preferably less than 5.0 μm. When the average dispersed particle size of the elastomer is less than 5.0 μm, the dispersibility of the elastomer is good. Therefore, the present film is likely to have excellent flexibility, electrical insulation, heat resistance, etc. The lower limit of the average dispersed particle size is not particularly limited, but may be, for example, 0.1 μm. The "average dispersed particle size" of the elastomer is the arithmetic average of the maximum diameters measured for 100 randomly selected domains (dispersed particles) when the cross section of the present film is observed with a scanning electron microscope (SEM).

[0049] The composition constituting the present film may further contain other components in addition to the crystalline resin and elastomer, as long as the effects of the present invention are not impaired. Examples of other components include inorganic fillers, polymer fillers, plasticizers, and flame retardants. The other components may be used alone or in combination of two or more.

[0050] Examples of inorganic fillers include glass fiber, carbon fiber, carbon black, graphite, graphene, carbon nanotubes, gypsum fiber, mica, talc, glass flakes, wollastonite, potassium titanate, aluminum borate, boron nitride, aluminum nitride, calcium carbonate, magnesium oxide, tin oxide, silicon oxide (silica), titanium oxide, barium sulfate, zinc oxide, aluminum hydroxide, magnesium hydroxide, clay, white carbon, carbon black, inorganic pigments, molybdenum disulfide, metal powder, magnetic materials, and zeolites.

[0051] Examples of the glass fiber include chopped fiber, milled fiber, and flat glass fiber having a modified cross section. In addition, glass fiber having a low dielectric constant may be used in terms of electrical properties.

[0052] Examples of carbon fibers include PAN-based carbon fibers, pitch-based isotropic carbon fibers, and pitch-based anisotropic carbon fibers. The shape of the carbon fibers can be selected from chopped fibers and milled fibers depending on the desired physical properties.

[0053] Examples of carbon black include furnace black, acetylene black, thermal black, and channel black. Among the many carbon blacks, furnace black is preferred. Examples of furnace black include HAF-LS carbon, HAF carbon, HAF-HS carbon, FEF carbon, GPF carbon, APF carbon, SRF-LM carbon, SRF-HM carbon, and MT carbon, with MT carbon being preferred.

[0054] Examples of polymer fillers include polycarbonate, polyarylate, polycaprolactone, phenoxy resin, polysulfone, polyethersulfone, polyimide, polyetherimide, polyphenylene oxide, polytetrafluoroethylene, acrylonitrile-butadiene-styrene copolymer (ABS resin), polymethyl methacrylate, polybutadiene, butadiene-styrene copolymer, ethylene-propylene-diene rubber (EPDM), butadiene-acrylonitrile copolymer, acrylic rubber, styrene-maleic anhydride copolymer, styrene-phenylmaleimide copolymer, ethylene / acrylic acid / glycidyl methacrylate copolymer, and aramid. Among the many polymer fillers, polytetrafluoroethylene is preferably used when reducing the dielectric constant and dielectric loss tangent of the film.

[0055] Examples of the plasticizer include phthalate esters and adipate esters. Examples of the flame retardant include aluminum hydroxide, magnesium hydroxide, magnesium carbonate, antimony trioxide, sodium antimonate, antimony pentoxide, phosphazene compounds, phosphate esters (triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl phenyl phosphate, 2-ethylhexyl diphenyl phosphate, etc.), ammonium polyphosphate, melamine-melam-melem polyphosphate, red phosphorus, molybdenum compounds, boric acid compounds, and polytetrafluoroethylene.

[0056] When the present composition further contains components other than the crystalline resin and the elastomer, the total amount of such other components is preferably 0.1 to 50% by volume, more preferably 1 to 40% by volume, and even more preferably 3 to 30% by volume.

[0057] The melt viscosity of the composition is preferably 100 to 1,000 Pa s, more preferably 200 to 500 Pa s, and even more preferably 300 to 420 Pa s. When the melt viscosity is within this range, the composition has high fluidity, and the composition is likely to be easily melt-formed into a film.

[0058] The composition constituting the present film can be prepared, for example, by melt-kneading a crystalline resin, an elastomer, and, if necessary, other components. When other components are contained in the present composition, the other components may be added when the crystalline resin and the elastomer are melt-kneaded, or may be added after the crystalline resin and the elastomer are melt-kneaded.

[0059] From the viewpoint of ease of handling, the elastomer before melt-kneading is preferably in a crumb state. The number average particle size of the elastomer before melt-kneading is preferably 10 mm or less, more preferably 8 mm or less, and even more preferably 6 mm or less. When the number average particle size of the elastomer before melt-kneading is within the above range, the conveyability by the screw during melt-kneading tends to be stable.

[0060] The details and preferred embodiments of the volume ratio of the crystalline resin to the elastomer in melt-kneading are the same as those described above for the volume ratio of the crystalline resin to the elastomer in the present composition. When the volume ratio of the crystalline resin and the volume ratio of the elastomer are within the above-mentioned ranges, the strand obtained during melt-kneading has little rough appearance. When the total volume ratio of the crystalline resin and the volume ratio of the elastomer is within the above-mentioned range, and the volume ratio of the crystalline resin is within the above-mentioned range, flexibility is easily exhibited.

[0061] Various devices can be used as the melt-kneading device. For example, a single-screw extruder or a twin-screw extruder is preferred, a twin-screw extruder is more preferred, and a twin-screw extruder equipped with a screw with a high kneading effect is even more preferred. As a screw with a high kneading effect, one can select one that has a sufficient kneading effect on the material to be melt-kneaded and does not apply excessive shear force. An example of the melt-kneading device is a Labo Plastomill kneader (manufactured by Toyo Seiki Seisakusho Co., Ltd.).

[0062] The crystalline resin and the elastomer may be mixed in advance and fed to the melt-kneading apparatus, or the crystalline resin and the elastomer may be fed separately to the melt-kneading apparatus. When other components are contained in the composition, the other components may be mixed in advance with either the crystalline resin or the elastomer and the other component and fed to the melt-kneading apparatus, or may be fed to the melt-kneading apparatus separately from the crystalline resin and the elastomer. Alternatively, the other components may be added after the crystalline resin and the elastomer are melt-kneaded.

[0063] The melt-kneading is preferably carried out so that an elastomer having an average dispersed particle size of less than 5.0 μm is dispersed in the crystalline resin, for example, by appropriately adjusting the melt viscosity ratio, melt-kneading temperature, extrusion shear rate, and residence time of the material to be melt-kneaded in the melt-kneading device.

[0064] The melt-kneading temperature is preferably set depending on the crystalline resin and elastomer. The melt-kneading temperature is preferably 200 to 450°C, more preferably 240 to 400°C, even more preferably 250 to 350°C, and particularly preferably 280 to 330°C. When the melt-kneading temperature is within the above range, the elastomer is easily dispersed in the crystalline resin, and coarse particles of the elastomer are less likely to remain. In addition, the elastomer is less susceptible to thermal decomposition, and is likely to have excellent heat resistance.

[0065] The extrusion shear rate in the melt-kneading is preferably set according to the melt viscosity of the material to be melt-kneaded at the melt-kneading temperature. －１ is preferred, and 10 to 2000 seconds －１More preferably, 15 to 1500 seconds －１ When the extrusion shear rate is within the above range, the elastomer is easily dispersed in the crystalline resin, and coarse particles of the elastomer are less likely to remain. In addition, the elastomer is less likely to be thermally decomposed, and heat resistance is likely to be excellent.

[0066] The residence time of the material to be melt-kneaded in the melt-kneading device is preferably 10 to 290 seconds, more preferably 20 to 240 seconds, and even more preferably 30 to 210 seconds. When the residence time of the material to be melt-kneaded in the melt-kneading device is within this range, the elastomer is easily dispersed in the crystalline resin, and coarse particles of the elastomer are less likely to remain. In addition, thermal decomposition of the elastomer is less likely to be promoted.

[0067] The melt-kneading is preferably carried out substantially in the absence of a crosslinking agent and a crosslinking aid. Melt-kneading substantially in the absence of a crosslinking agent and a crosslinking aid means melt-kneading without substantially crosslinking the elastomer in the composition. Whether the elastomer in the composition is substantially uncrosslinked can be confirmed by the flexural modulus value of the composition. If the elastomer is substantially crosslinked, the flexibility of the elastomer is lost, resulting in a flexural modulus exceeding 3.7 GPa. When melt-kneading is carried out substantially in the absence of a crosslinking agent and a crosslinking aid, the flexibility of the elastomer in the composition can be ensured.

[0068] However, the melt-kneading may be carried out in the presence of a crosslinking agent and a crosslinking aid. When the melt-kneading is carried out in the presence of a crosslinking agent and a crosslinking aid, the crosslinking agent and the crosslinking aid may be used in amounts within a range that ensures the thermoplasticity of the composition.

[0069] [Method for Manufacturing Film for Motor Insulating Paper] Another embodiment of the present invention relates to a method for manufacturing a film for motor insulating paper (hereinafter also referred to as "the manufacturing method"), in which a composition containing a thermoplastic crystalline resin and an elastomer (the composition) is melt-molded and then cooled at 180°C or higher, the thickness of the film being 50 to 1000 μm, the dimensional change rate calculated by the following formula (X) being less than 10%, the elastomer being dispersed in the crystalline resin, and the degree of crystallinity relative to the degree of crystallinity of the crystalline resin being 95% or less. Dimensional change rate (%) = (1 - (L １ / L ０ ))×100...(X) In formula (X), L ０ and L １ The details and preferred embodiments of the crystalline resin, elastomer and present composition in the present production method are the same as those of the crystalline resin, elastomer and present composition in the present film.

[0070] Examples of methods for melt-molding the composition into a film include extrusion molding using a T-die, press molding (thermoforming), and injection molding. Among these methods, extrusion molding is preferred from the viewpoint of ease of cooling after melt molding.

[0071] The cylinder temperature in the extruder is preferably 300 to 420° C., more preferably 330 to 370° C. The T-die temperature is preferably 350 to 420° C., more preferably 350 to 380° C. When the T-die temperature is within the above range, the frictional stress between the molten composition and the T-die is reduced, and decomposition of the crystalline resin and elastomer due to thermal history during molding is likely to be suppressed, and the surface smoothness of the obtained film is likely to be improved.

[0072] The extrusion shear rate in the extruder is 3 to 2500 seconds －１ is preferred, and 10 to 1000 seconds －１ More preferably, 10 to 100 seconds －１ The residence time of the composition in the extruder is preferably from 10 to 1,000 seconds, more preferably from 60 to 500 seconds.

[0073] This production method is characterized by melt-molding the composition into a film and then cooling it to 180°C or higher. By cooling the film under these conditions, the elastomer is more likely to function as a crystal nucleating agent, making it easier for the above-mentioned mechanism to manifest. As a result, the properties inherent to the crystalline resin and elastomer are more fully exhibited, resulting in a film with excellent heat resistance, electrical insulation, and dimensional stability.

[0074] The film may be cooled from one side or both sides of the melt-molded film. For example, the melt-molded film can be cooled to 180°C or higher by passing one or both sides of the film melt-molded by extrusion molding using a T-die through a metal roll having a surface temperature of 180°C or higher while contacting the metal roll.

[0075] The contact time between one or both sides of the melt-formed film and the metal roll having a surface temperature of 180°C or higher is usually preferably in the range of 10 to 100 seconds. By cooling the melt-formed film for a contact time within this range, the elastomer is maintained dispersed in the crystalline resin in the melt-formed composition, and the dispersed elastomer is likely to function as a crystal nucleating agent that increases the crystallization rate of the film. From the viewpoint of uniforming the physical properties of the resulting film and making it easier to exhibit the above-mentioned properties, it is more preferable in the present production method to cool the melt-formed film from both sides.

[0076] Particularly preferred is a film in which the crystalline resin is PPS or PEEK, the fluoroelastomer is TFE / P, HFP / VdF (FKM), or TFE / PMVE / PPVE (FFKM), the average dispersed particle size of the fluoroelastomer is less than 5.0 μm, the thickness is 50 to 1000 μm, the dimensional change rate calculated by formula (X) is less than 10%, the elastomer is dispersed in the crystalline resin, and the crystallinity relative to the crystallinity of the crystalline resin is 95% or less. Such a film has a well-balanced and excellent mechanical properties such as bending resistance and flexibility, heat resistance such as dimensional stability, and electrical properties such as electrical insulation.

[0077] The present film may be used as a composite by being combined or laminated with other materials than the present film, such as metals, glass, resins, and rubbers.

[0078] Examples of the resin include those described in International Publication No. 2015 / 182702, liquid crystal polymers, polyaryl ketones, polyethersulfones, polyphenylsulfones, polyacetals, polyurethanes, and polyamides. Examples of the polyamides include polyamide 6, polyamide 66, polyamide 46, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide 6 / 66 copolymer, polyamide 6 / 66 / 610 copolymer, polyamide MXD6, polyamide 6T, polyamide 9T, and polyamide 6 / 6T copolymer.

[0079] The present film can be particularly suitably used as a film for motor insulating paper that constitutes an insulating sheet for rotating electrical machines such as motors, generators, inverters, etc. The present invention includes motor insulating paper that includes the present film.

[0080] One application of motor insulating paper equipped with this film is as an insulating material for electric vehicle motors. As power and voltage increase to improve driving range, insulating materials for electric vehicle motors are required to have heat resistance and excellent electrical insulation properties, and this film can be used effectively.

[0081] Specifically, rotating electrical machines such as motors and generators have coils formed by winding enameled wires (windings)—thin copper wires insulated with enamel varnish—into an oval shape. Such coils are typically composed of multiple interconnected segment conductors and are mounted in a component called a stator core or rotor core, which is typically made of laminated magnetic steel plates. The stator core or rotor core has multiple slots. The coils are housed in the slots via slot liners that ensure insulation between the inner wall surfaces of the slots and the coils. Motor insulating paper equipped with the present film is particularly suitable for use as such slot liners. The present film can also be used as a film for generator insulating paper or inverter insulating paper.

[0082] The present film can also be suitably used for speaker diaphragms, plates for trauma and fractures, insulating paper such as various types of electrical insulating adhesive tapes, sealing tape for oil and natural gas pipes, release film, film for covering electric wires, flexible printed circuit boards, rigid circuit boards, coverlay, housings for electronic devices, heat-resistant rolls for office automation equipment, films for impregnating other fiber composite films, insulating tape for fixing elements in film capacitors, and electrolytic capacitors such as aluminum and tantalum.

[0083] The present film, its manufacturing method, and usage modes of the present film have been described above, but the present invention is not limited to the configurations of the above-described embodiments. For example, the present film may have any other additional configuration in addition to the configurations of the above-described embodiments, or may be replaced with any other configuration that produces a similar effect. The usage modes of the present film may have any other additional configuration in addition to the configurations of the above-described embodiments, or may be replaced with any other configuration that produces a similar effect.

[0084] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to these examples. Examples 1 to 5 and 7 to 11 are working examples, and Examples 6 and 12 are comparative examples.

[0085] [Raw Materials] Details of the raw materials used in each example are shown below.

[0086] (Thermoplastic crystalline resin) Crystalline resin A1: PEEK (manufactured by Daicel-Evonik, product name "VESTAKEEP3300G", melt viscosity: 20 Pa s (380°C / 5 kg), melting point: 340°C, specific gravity: 1.32 g / cm ３ Crystalline resin A2: PPS (linear type, Solvay Specialty Polymers product "160P", melt viscosity: 358 Pa s, melting point: 280 ° C, specific gravity: 1.34 g / cm ３ ).

[0087] (Elastomer) Elastomer B1: a fluoroelastomer having a TFE unit:P unit ratio of 56:44 and no terminal functional group, melt viscosity: 1726 Pa s, specific gravity: 1.55 g / cm ３ , Mooney viscosity (ML １＋１０ , 121°C): 100, storage modulus G': 390. Elastomer B2: a fluoroelastomer having a TFE unit:P unit ratio of 56:44 and having 0.4% by mass of iodine atoms as terminal functional groups relative to the mass of the fluoroelastomer, melt viscosity: 354 Pa s, specific gravity: 1.55 g / cm ３ , Mooney viscosity (ML １＋１０ , 121°C): 50, storage modulus G': 250).

[0088] 1. Film Production Examples [Example 1] Crystalline resin A1 and elastomer B1 were mixed in the volume ratio shown in Table 1 and then added to the base end of the screw of a twin-screw extruder (Technovel Co., Ltd., KZW32TW-45MG-NH(-1500), screw diameter: 30 mmΦ, L / D: 24) using a feeder so as to achieve a flow rate of 15.0 kg / hour. The screw rotation speed was 200 rpm, and the cylinder, die, and head temperatures were set as follows: C1 = 340°C, C2 = 360°C, C3 = 370°C, C4 = 370°C, C5 = 370°C, C6 = 370°C, AD = 350°C, and H = 360°C. The strand extruded from the die tip was air-cooled and cut with a pelletizer to obtain pellets of Composition 1. The pellets of Composition 1 were then pre-dried for 3 hours at 200°C. Composition 1 was extruded into a film using a single-screw extruder (VS-30, manufactured by Tanabe Plastics Machinery Co., Ltd.) and a 250 mm wide T-die at a cylinder temperature of 330°C to 370°C, a die temperature of 370°C, a rotation speed of 36 rpm, and a take-up speed of 1.2 m / min. The film was then cooled by passing it through metal rolls maintained at 180°C so that both sides of the film were in contact with each other, thereby obtaining a film with a thickness of 150 μm.

[0089] [Examples 2 to 6] Pellets of compositions 2 to 6 were obtained under the same conditions as in Example 1, except that the volume ratio of crystalline resin A1 and elastomer B1 was changed as shown in Table 1. When it was difficult to form strands, the compositions were water-cooled instead of air-cooled and cut with a pelletizer. Next, compositions 2 to 6 were extruded into a film under the same conditions as in Example 1, and then cooled by passing one side of the film through a metal roll maintained at the temperature shown in Table 1, thereby obtaining a film with a thickness of 150 μm.

[0090] Example 7 Crystalline resin A2 and elastomer B2 were mixed in the volume ratio shown in Table 2 and then introduced into the base end of the screw of a twin-screw extruder (Technovel Co., Ltd., KZW32TW-45MG-NH(-1500), screw diameter: 30 mmΦ, L / D: 24) using a feeder so that the flow rate was 15.0 kg / hour. The screw rotation speed was 200 rpm, and the cylinder, die, and head temperatures were set as follows: C1 = 270°C, C2 = 280°C, C3 = 290°C, C4 = 290°C, C5 = 290°C, C6 = 290°C, AD = 280°C, and H = 280°C. The strand extruded from the die tip was air-cooled and cut with a pelletizer to obtain pellets of Composition 7. The pellets of Composition 7 were then pre-dried for 3 hours at 200°C. Composition 7 was extruded into a film using a single-screw extruder (VS-30, manufactured by Tanabe Plastics Machinery Co., Ltd.) and a 250 mm wide T-die at a cylinder temperature of 290°C to 330°C, a die temperature of 290°C, a rotation speed of 33 rpm, and a take-up speed of 1.0 m / min. The film was then cooled by passing it through metal rolls maintained at 180°C so that both sides of the film came into contact with each other, thereby obtaining a film with a thickness of 150 μm.

[0091] [Examples 8 to 12] Pellets of compositions 8 to 12 were obtained under the same conditions as in Example 1, except that the volume ratio of crystalline resin A2 and elastomer B2 was changed as shown in Table 1. When it was difficult to form strands, they were water-cooled instead of air-cooled and cut using a pelletizer. Next, compositions 8 to 12 were extruded into films under the same conditions as in Example 7, except that the cylinder rotation speed of the single-screw extruder was changed to 27 rpm in Example 10, 20 rpm in Example 11, and 13.5 rpm in Example 12. Then, the films were cooled by passing them through a metal roll maintained at the temperature shown in Table 2 so that one side of the film was in contact with the metal roll, to obtain a film with a thickness of 150 μm.

[0092] 2. Film Evaluation 2-1. Dimensional Change Rate Test pieces were prepared from the films obtained in each example, and the length in the MD direction (L ０ ) and left in an oven at 200°C for 1 hour. Immediately after being taken out of the oven, the length (L １ ) was measured, and the dimensional change rate was calculated based on the following formula (X): Dimensional change rate (%) = (1 - (L１ / L ０ ))×100...(X) L ０ : Length of film test piece in MD direction L １ : Length in the MD direction of the film after leaving it at 200°C for 1 hour

[0093] 2-2. Crystallinity A differential scanning calorimeter (DSC7020, manufactured by Hitachi High-Tech Science Corporation) was used. Measurement samples were prepared from the films obtained in each example, and the temperature was raised at a rate of 10°C / min. The heat of fusion was determined from the endothermic peak area of ​​the second heating, and the crystallinity was calculated using the following formula: Crystallinity (%) = Measured heat of fusion (J / g) / Equilibrium heat of fusion (J / g).

[0094] Dumbbell-shaped test pieces as specified in ASTM D638 TYPE V were cut out from the films obtained in each example, and the tensile modulus was measured using a TENSILON (manufactured by A&D Co., Ltd., model: RTF-1350) in accordance with JIS K7161 (corresponding international standard ISO 527-1:2012) with a load cell rating of 10 kN, a chuck distance of 115 mm, and a speed of 50 mm / min.

[0095] 2-4. Breakdown voltage An impulse partial discharge tester (DWX-05PD, manufactured by Electronic Control International Co., Ltd.) was used for the measurements. The film obtained in each example was placed on a PD sensor distance of 10 cm and a φ25 flat test electrode. The device was then set to 1.5 kV at the start of the test, 3.7 kV at the end of the test, with a step of 2%, and measurements were taken at three different locations per sheet, seven times per test. The breakdown voltage was obtained as the average of the last five measurements. Measurements were performed at 23°C.

[0096] The evaluation results are shown in Tables 1 and 2.

[0097]

[0098]

[0099] The films of Examples 1 and 7 have a good balance of excellent mechanical properties, heat resistance (dimensional change rate), and electrical insulation. Examples 2, 4, and 5 show that as the elastomer content in the composition constituting the film increases, the ratio of the film's crystallinity to that of the crystalline resin A1 constituting the composition decreases, improving electrical insulation. Examples 8, 10, and 11 show that as the elastomer content in the composition constituting the film increases, the ratio of the film's crystallinity to that of the crystalline resin A2 constituting the composition decreases, reducing the dimensional change rate. The films of Examples 2 and 3 differ in the cooling temperature after melt molding of the composition, and even though the ratio of the film's crystallinity to that of the crystalline resin A1 constituting the composition is similar, the film of Example 3 has a higher dimensional change rate. A similar trend was observed for the films of Examples 8 and 9, with the film of Example 9 having a higher dimensional change rate.

[0100] 2-5. Relative Dielectric Constant Square test pieces with sides of 80 mm were cut out from each of the films obtained in Examples 1, 6, 7, and 12. Using these test pieces, the relative dielectric constants were measured at 25°C and 200°C using a Precision LCR Meter E4980A (manufactured by Agilent Technologies) in accordance with JIS C 2138 (automatic balancing bridge method) at three frequencies of 60 Hz, 1 kHz, and 1 MHz, with n (number of tests) = 2. Conductive silver paint was used for the electrodes, with a main electrode diameter of 36 mm and an annular electrode with an inner diameter of 38 mm.

[0101] 2-6. Partial Discharge Inception Voltage (PDIV) Square test pieces measuring 50 mm on a side were cut out from each of the films obtained in Examples 1, 6, 7, and 12, and the partial discharge inception voltages (PDIV) of the test pieces were measured using a partial discharge meter (model number "QM-50") manufactured by Mitsubishi Electric Wire Industries, Ltd. For the measurement, the test pieces were sandwiched between a stainless steel plate and a brass electrode, and an AC voltage was applied to the stainless steel plate and the brass electrode at a voltage increase rate of 200 Vrms / sec. The voltage value when the discharge charge amount measured by the partial discharge meter reached 100 pC was determined. PDIV was measured at 25°C and 150°C, and the PDIV measured value (relative value) at 150°C relative to the PDIV measured value at 25°C was determined. The test piece was also immersed in oil for a long period of time, and after wiping off the oil, the PDIV was measured at 25°C. The measured value after immersion in oil (relative value) to the measured value before immersion in oil was calculated and used as an index of oil resistance. The results are shown in Table 3.

[0102]

[0103] The film of the present invention has a well-balanced and excellent mechanical properties such as bending resistance and flexibility, heat resistance such as dimensional stability, and electrical properties such as electrical insulation, and is therefore suitable for use as a film for motor insulating paper constituting insulating sheets for rotating electrical machines such as motors, generators, and inverters.

[0104] This application claims priority based on Japanese Patent Application No. 2023-174235, filed on October 6, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A film for motor insulating paper, which is melt-molded from a composition containing a thermoplastic crystalline resin and an elastomer, has a thickness of 50 to 1000 μm, has a dimensional change rate calculated by the following formula (X) of less than 10%, the elastomer is dispersed in the crystalline resin, and has a crystallinity of 95% or less relative to the crystallinity of the crystalline resin. Dimensional change rate (%) = (1 - (L １ / L ０ ))×100...(X) In formula (X), L ０ is the length of the film for motor insulating paper in the MD direction, and L １ is the length in the MD direction of the film for motor insulating paper after the film for motor insulating paper is left at 200° C. for 1 hour.

2. The film for motor insulating paper according to claim 1, wherein the crystalline resin is at least one selected from the group consisting of polyarylsulfone, polyarylene sulfide, polyethersulfone, polyaryletherketone and liquid crystal polyester.

3. The film for motor insulating paper according to claim 1, wherein the elastomer is a fluoroelastomer.

4. The film for motor insulating paper according to claim 1, wherein the content of the elastomer relative to the total of the crystalline resin and the elastomer is 1 volume % or more and 50 volume % or less.

5. The film for motor insulating paper according to claim 1, having a tensile modulus of elasticity of 3600 MPa or less.

6. The film for motor insulating paper according to claim 1, wherein the crystallinity of the crystalline resin is 10% or more and 70% or less.

7. The film for motor insulating paper according to claim 1, having a relative dielectric constant of less than 3.

5.

8. The film for motor insulating paper according to claim 1, which has a thickness of 500 μm or less.

9. The film for motor insulating paper according to claim 1, wherein the average dispersed particle size of the elastomer is less than 5.0 μm.

10. A method for producing a film for motor insulating paper, comprising melt-molding a composition containing a thermoplastic crystalline resin and an elastomer, followed by cooling at 180°C or higher, the film has a thickness of 50 to 1000 μm, a dimensional change rate calculated by the following formula (X) is less than 10%, the elastomer is dispersed in the crystalline resin, and the degree of crystallinity relative to the degree of crystallinity of the crystalline resin is 95% or less. Dimensional change rate (%) = (1 - (L １ / L ０ ))×100...(X) In formula (X), L ０ is the length of the film for motor insulating paper in the MD direction, and L １ is the length in the MD direction of the film for motor insulating paper after the film for motor insulating paper is left at 200° C. for 1 hour.

11. The method of claim 10, wherein the cooling is effected from both sides of the melt-formed film.

12. The method according to claim 10, wherein the crystalline resin is at least one selected from the group consisting of polyarylsulfone, polyarylene sulfide, polyethersulfone, polyaryletherketone and liquid crystal polyester.

13. The method of claim 10, wherein the elastomer is a fluoroelastomer.

14. The method according to claim 10, wherein the content of said elastomer relative to the total content of said crystalline resin and said elastomer is 1 volume % or more and 50 volume % or less.

15. A motor insulating paper comprising the film for motor insulating paper according to any one of claims 1 to 9.

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