CN115668698A

CN115668698A - Film for motor, and method for manufacturing film for motor

Info

Publication number: CN115668698A
Application number: CN202180038420.7A
Authority: CN
Inventors: 大崎桂史; 莲池真保
Original assignee: Mitsubishi Chemical Corp
Current assignee: Mitsubishi Chemical Corp
Priority date: 2020-05-27
Filing date: 2021-05-26
Publication date: 2023-01-31
Also published as: JP2021188047A; WO2021241632A1

Abstract

A thin film for a motor, which has excellent insertion properties into a motor core or the like by improving sliding properties and is made thin, is provided, which is a resin film having a tensile elastic modulus of 2500MPa or more and a compressive strength of 50 to 1300N, and has an arithmetic average roughness (Ra) of more than 0.1 [ mu ] m on at least one surface.

Description

Film for motor, and method for manufacturing film for motor

Technical Field

The present invention relates to a thin film for a motor, which has excellent insertion properties by improving sliding properties, and particularly relates to a thin film that can be suitably used as wedge paper or slot paper.

Background

In motors that are driving forces for home appliances, industrial equipment, and the like, slot paper (slot paper) and wedge paper (wedge paper) that closes the slot opening from the inside have been conventionally provided as insulating films that are sandwiched between a core and a winding coil in a slot in a stator core. These insulating films are usually assembled by being inserted into slots from openings in the end faces of the stator core.

In recent years, the performance of motors has been improved, and in particular, small-sized and high-efficiency motors have been required. Therefore, a method of thinning an insulating film and increasing a space factor of a wound coil is sometimes adopted, and accordingly, a thin film is required for an insulating film such as a wedge paper or a slot paper, and further, excellent insertion property is required.

Further, since heat is likely to be accumulated in the motor due to downsizing, the refrigerant may be directly impregnated into the stator core or the rotor core, and chemical resistance to the refrigerant or the like is also required in addition to heat resistance.

As such an insulating film, aramid paper having surface properties superior to those of general resin films and the like, a laminate obtained by laminating aramid paper and a resin film with an adhesive, and the like are widely used.

However, aramid paper is more likely to be thinned than resin films and the like, and thus, it is difficult to reduce the thickness while suppressing a decrease in insulation reliability.

Further, since aramid paper has no hardness and is easily buckled compared to a resin film having the same thickness, if the aramid paper is thinned, buckling may occur when the aramid paper is inserted into a groove.

In addition, since a laminate of aramid paper and a resin film is originally commercially available as a product of only 50 μm or more, when a plurality of sheets are laminated, the thickness becomes large, usually about several hundreds of μm, and it is difficult to use the laminate for a small-sized and high-efficiency motor.

Further, the fibers of the aramid paper may be fluffed when cut or inserted, and remain inside the motor as foreign matter, thereby causing abrasion of the rotor and significantly reducing the motor performance.

As a method for solving these problems, for example, patent document 1 discloses an insulating sheet having a predetermined surface roughness, and describes that the insulating sheet can have a slidability equivalent to that of aramid paper. Further, it describes: the arithmetic average roughness (Ra) of the insulating sheet is 0.05 μm or more and 0.1 μm or less, and when the arithmetic average roughness (Ra) deviates from the above range, the slidability is poor and the insertability may be lowered.

Documents of the prior art

Patent literature

Patent document 1: japanese laid-open patent publication No. 2009-055678

Disclosure of Invention

Problems to be solved by the invention

Focusing on the arithmetic average roughness (Ra), the present inventors have further studied and found that: the thickness and hardness of the film are related to the roughness of the surface of the film, and for example, with a thickness of the degree described in the example of patent document 1, even if the slidability is not a problem when actually inserting the film into the motor, the slidability described in patent document 1 is insufficient when the thickness is further reduced or when a film using a resin having low hardness is desired to be inserted into the motor.

The present invention has been made under such circumstances, and provides a film for a motor, which has improved slidability and thus has excellent insertion properties.

Means for solving the problems

As a result of intensive studies, the present inventors have succeeded in obtaining a thin film for a motor capable of solving the above-mentioned problems of the prior art by imparting specific surface properties to the surface of a thin film having a specific thickness and a specific compressive strength.

Namely, the present invention provides the following [1] to [14].

[1] A film for a motor, which is a resin film having a tensile modulus of elasticity of 2500MPa or more and a compressive strength of 50 to 1300N, and at least one surface of which has an arithmetic average roughness (Ra) of more than 0.1 [ mu ] m.

[2] A film for a motor, which is a resin film having a tensile elastic modulus of 2500MPa or more and a thickness of less than 300 μm, and at least one surface of which has an arithmetic average roughness (Ra) of more than 0.1 μm.

[3] The film for a motor according to [1] or [2], wherein the arithmetic average roughness (Ra) is 2 μm or less.

[4] The film for a motor according to any one of [1] to [3], wherein an arithmetic average height (Sa) of at least one surface of the film is 0.1 to 3 μm.

[5] The film for a motor according to any one of [1] to [4], wherein a maximum height roughness (Rz) of at least one surface of the film is1 to 10 μm.

[6] The thin film for a motor according to any one of [1] to [5], wherein a maximum height (Sz) of at least one surface of the thin film is 1.5 to 30 μm.

[7] The film for a motor according to any one of [1] to [6], wherein the film contains at least 1 material selected from the group consisting of polyether ether ketone and polyetherimide.

[8] The film for a motor according to any one of [1] to [7], wherein a coefficient of dynamic friction between at least one surface of the film and a stainless steel plate is 0.28 or less.

[9] The film for a motor according to any one of [1] to [8], wherein a static friction coefficient between at least one surface of the film and a stainless steel plate is 0.42 or less.

[10] The thin film for a motor according to any one of [1] to [9], wherein the number of folding endurance is 50 or more at a thickness of 100 μm.

[11] The film for a motor according to any one of [1] to [10], which is a wedge-shaped paper.

[12] The film for a motor according to any one of [1] to [10], which is a slot paper.

[13] A motor using the film for a motor according to any one of [1] to [12 ].

[14] The method for producing a film for a motor according to any one of [1] to [12], wherein the film is produced by extrusion molding using a casting roll having an arithmetic average roughness (Ra) of 0.1 to 2 μm.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a film for a motor having excellent insertion properties can be provided despite being a resin film having low hardness and being at least one of thin and thin.

Drawings

Fig. 1 is a conceptual perspective view for explaining the insertion test.

Detailed Description

The present invention is not limited to the embodiments described below as long as the invention does not depart from the gist thereof.

The compressive strength in the present invention means: values measured according to JIS P8126:2015 by the method described in the examples below.

The arithmetic average roughness (Ra) and the maximum height roughness (Rz) in the present invention mean: measured by the method described in the examples below using a contact surface roughness meter in accordance with JIS B0601: 2013.

The arithmetic mean height (Sa) and the maximum height (Sz) in the present invention are: the values measured by the method described in the examples below using a white interference microscope.

The dynamic friction coefficient and the static friction coefficient in the invention refer to: the measured values were obtained by the methods described in examples described later with reference to JIS K7125: 1999.

In the present invention, "film" means a film which is not distinguished from "sheet" and includes the film.

In the present invention, unless otherwise specified, the expression "X to Y" (X and Y are arbitrary numbers) includes the meaning of "X to Y inclusive" and includes the meanings of "preferably greater than X" and "preferably less than Y".

In the present invention, the meaning of "preferably more than X" is included in the case of "X or more" (X is an arbitrary number) unless otherwise specified, and the meaning of "preferably less than Y" is included in the case of "Y or less" (Y is an arbitrary number) unless otherwise specified.

In the present invention, the "main component" is the largest component in the object, and is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass, particularly preferably 80% by mass or more, and most preferably 90% by mass or more in the object.

A film for a motor according to an embodiment of the present invention (hereinafter, may be referred to as "the present film") is a resin film having a tensile elastic modulus of 2500MPa or more, a compressive strength of 50 to 1300N, and a thickness of less than 300 μm, and has a surface having a surface roughness with an arithmetic average roughness (Ra) of more than 0.1 μm on at least one surface. The film is a film for a motor, and therefore, is generally an insulator.

That is, the present film according to one embodiment of the present invention has a tensile elastic modulus of 2500MPa or more, a compressive strength of 50 to 1300N, and an arithmetic average roughness (Ra) of at least one surface of the film exceeding 0.1. Mu.m.

The present film according to another embodiment of the present invention has a tensile elastic modulus of 2500MPa or more, a thickness of less than 300 μm, and an arithmetic average roughness (Ra) of at least one surface of more than 0.1. Mu.m, and preferably further has the above-mentioned specific compressive strength.

The front and back surfaces of the resin film are not necessarily required to have the surface roughness, and a resin film in which the arithmetic average roughness (Ra) on one surface side exceeds 0.1 μm and the surface on the other surface side is smoothly formed may be used so that only the surface side in contact with the wound coil or the inner wall surface has the roughness.

The following description is made in detail.

[ Material Components of resin film ]

The resin material of the resin film used in the present film is not particularly limited, and for example, engineering plastics having heat resistance of 100 ℃ or higher and chemical resistance against refrigerants such as oil and the like are preferable, and super engineering plastics are more preferable, as the motor is downsized and highly efficient, and the present film preferably does not contain 5 mass% or more of a fluororesin, more preferably does not contain 3 mass% or more, further preferably does not contain 1 mass% or more, and particularly preferably does not substantially contain the fluororesin, from the viewpoint of reducing the amount of generation of pollution, corrosion, and decomposition gas in manufacturing facilities such as an extruder.

Specific examples thereof include polyaryletherketones such as polyetheretherketone, polyetherketoneketone, polyetherketone, polyetherketoneetherketoneketone, polyaryletherketoneketone, polyaryletheretherketone, polyetheretherketoneketone, and polyaryletherketoneketone; polyether imide, polyether imide sulfone, polyamide, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, polyarylate, polysulfone, polyether sulfone, polyamide imide, polyimide, polymethylpentene, a liquid crystal polymer and the like, and these may be used singly or in combination of two or more, and as one layer, it is preferable to use singly or as a main component.

Among them, polyether ether ketone and polyether imide are suitable.

The present film may be a single layer or a multilayer, and in the case of a multilayer, the present film may be: a resin film having a two-layer structure in which, for example, polyether ether ketone is used for one layer and different resins are laminated using polyether imide or the like for the other layer; or a resin film having a laminated structure of 3 or more layers.

(polyetheretherketone)

The polyether ether ketone may be a resin having at least two ether groups and a ketone group as a structural unit, and preferably has a repeating unit represented by the following general formula (1) in view of excellent thermal stability, melt moldability, rigidity, chemical resistance, impact resistance, and durability.

(in the general formula (1), ar ¹ ～Ar ³ Each independently represents an arylene group having 6 to 24 carbon atoms and each optionally has a substituent

In the above general formula (1), ar ¹ ～Ar ³ The arylene groups in (a) may be different from each other, preferably the same. MakingIs the aforementioned Ar ¹ ～Ar ³ Examples of the arylene group in (b) include phenylene and biphenylene. Among them, phenylene group is preferable, and p-phenylene group is more preferable.

As the aforementioned Ar ¹ ～Ar ³ The arylene group (b) may have a substituent, and examples thereof include an alkyl group having 1 to 20 carbon atoms such as a methyl group and an ethyl group; alkoxy groups having 1 to 20 carbon atoms such as methoxy and ethoxy. In Ar, the following is ¹ ～Ar ³ When the substituent is present, the number of the substituent is not particularly limited.

Among them, polyether ketones having a repeating unit (a-1) represented by the following structural formula (2) are preferable from the viewpoints of thermal stability, melt moldability, rigidity, chemical resistance, impact resistance, and durability. The repeating unit (a-1) has two ether groups and one ketone group.

The total number of the repeating units of the polyether ether ketone represented by the formulae (1) and (2) (n: polymerization degree of the formulae (1) and (2)) is preferably 10 or more, and more preferably 20 or more. On the other hand, it is preferably 500 or less, more preferably 300 or less, and particularly preferably 100 or less. When the total number of repeating units (polymerization degree) of the polyether ether ketone is in this range, the film tends to have excellent chemical resistance, heat resistance and impact resistance, and also to have excellent melt moldability because the viscosity at the time of melting is not excessively high.

The number average molecular weight of polyether ether ketone is preferably 10000 or more, more preferably 12000 or more, further preferably 14000 or more, and particularly preferably 16000 or more. On the other hand, 35000 or less is preferable, 32000 or less is more preferable, 30000 or less is further preferable, and 28000 or less is particularly preferable. When the number average molecular weight of the polyether ether ketone is in this range, the film tends to have excellent chemical resistance, heat resistance and impact resistance, and also to have excellent melt moldability because the viscosity at the time of melting is not excessively high.

The number average molecular weight of polyether ether ketone can be determined as follows: an amorphous film of polyetheretherketone is dissolved in pentafluorophenol at 100 ℃ for 60 minutes, cooled naturally, and then chloroform at room temperature (23 ℃) is added to the solution, and the resulting sample solution is measured by gel permeation chromatography. The number average molecular weight can be determined by using pentafluorophenol/chloroform =1/2 (mass ratio) as an eluent and converting the column temperature of 40 ℃ to standard polystyrene.

The heat of fusion of the crystal of polyetheretherketone is preferably 20J/g or more, more preferably 25J/g or more, further preferably 30J/g or more, and particularly preferably 35J/g or more. On the other hand, it is preferably 60J/g or less, more preferably 55J/g or less, and further preferably 50J/g or less. When the heat of fusion of the crystal of polyetheretherketone is in this range, the film tends to have excellent heat resistance and to have low heat energy applied during melt molding, and thus the film tends to have excellent melt moldability.

The crystal melting temperature of polyether ether ketone is preferably 300 ℃ or higher, more preferably 320 ℃ or higher, further preferably 330 ℃ or higher, particularly preferably 335 ℃ or higher, and most preferably 340 ℃ or higher. On the other hand, the upper limit is preferably 400 ℃ or lower, more preferably 380 ℃ or lower, and still more preferably 360 ℃ or lower. When the crystal melting temperature of polyether ether ketone is in this range, the film tends to have excellent heat resistance and to have excellent melt moldability because the viscosity at the time of melting is not excessively high.

The glass transition temperature of polyetheretherketone is preferably 120 ℃ or higher, more preferably 130 ℃ or higher, and further preferably 140 ℃ or higher. On the other hand, it is preferably 200 ℃ or lower, more preferably 190 ℃ or lower, and still more preferably 180 ℃ or lower. When the glass transition temperature of polyether ether ketone is in this range, the film tends to have excellent heat resistance and to have excellent melt moldability because the viscosity at the time of melting is not excessively high.

The heat of fusion of the crystals in the present invention can be determined as follows: the temperature was raised in accordance with JIS K7122:2012 by using a differential scanning calorimeter (for example, pyris1 DSC manufactured by Perkin Elmer Co., ltd.) under the conditions of a temperature range of 25 to 400 ℃ and a heating rate of 10 ℃/min, and the temperature was determined from the area of the melting peak of the detected DSC curve.

The crystal melting temperature in the present invention can be determined as follows: according to JIS K7121:2012, the temperature was raised using a differential scanning calorimeter (for example, pyris1 DSC manufactured by Perkin Elmer Co., ltd.) under the conditions of a temperature range of 25 to 400 ℃ and a heating rate of 10 ℃/min, and the temperature was determined from the peak top temperature of the melting peak of the detected DSC curve.

The glass transition temperature in the present invention can be determined as follows: the temperature was raised in a temperature range of 25 to 400 ℃ at a heating rate of 10 ℃/min using a differential scanning calorimeter (for example, pyris1 DSC manufactured by Perkin Elmer Co., ltd.) in accordance with JIS K7121:2012, and the temperature was determined from the detected DSC curve.

The polyether ether ketone can be produced by a known production method, and a commercially available product can be used. Examples of commercially available products include "VICTREX PEEK" series manufactured by VICTREX, "ketspiral" series manufactured by Solvay, and "vestakep" series manufactured by Daicel Evonik.

(polyether imide)

The polyether imide is not particularly limited, and a polyether imide having a repeating unit represented by the following general formula (3) is preferably used.

(in the general formula (3), Y ¹ ～Y ⁶ Each independently represents a hydrogen atom, an alkyl group or an alkoxy group, ar ⁷ ～Ar ⁹ Each independently represents an arylene group having 6 to 24 carbon atoms which may have a substituent, X ¹ Represents a single bond, or-O-, -SO ₂ -, -S-, -C (= O) -or a divalent aliphatic hydrocarbon group. )

In the above general formula (3), ar ⁷ ～Ar ⁹ The arylene groups in (a) may be different from each other, preferably the same. As Ar ⁷ ～Ar ⁹ Arylene of (2), particularlyExamples thereof include phenylene and biphenylene, and among these, phenylene is preferred.

As Ar ⁷ ～Ar ⁹ Examples of the substituent optionally contained in the arylene group of (a) include an alkyl group having 1 to 20 carbon atoms such as a methyl group and an ethyl group; alkoxy groups having 1 to 20 carbon atoms such as methoxy and ethoxy. At Ar ⁷ ～Ar ⁹ When the substituent is present, the number of the substituent is not particularly limited.

Among these, from the viewpoint of mechanical properties, thermal stability and melt moldability, the repeating unit represented by the general formula (3) contained in the polyetherimide more preferably has a repeating unit (b-1) represented by the following structural formula (4) or a repeating unit (b-2) represented by the following structural formula (5).

Generally, polyetherimides are classified into structures according to the difference in bonding system, i.e., the difference between meta-bonding and para-bonding, and are different from each other in mechanical properties and heat resistance.

The total number of repeating units represented by the formulae (3) to (5) (n: polymerization degree of the formulae (3) to (5)) in the polyether imide is preferably 10 or more, more preferably 20 or more. On the other hand, the upper limit is preferably 1000 or less, more preferably 700 or less, and further preferably 500 or less. When the total number (polymerization degree) of the repeating units represented by the formulae (3) to (5) in the polyether imide is in this range, the film tends to have excellent heat resistance and to have excellent melt moldability because the viscosity at the time of melting is not excessively high.

The number average molecular weight of the polyetherimide measured by gel permeation chromatography is preferably 15000 or more, more preferably 20000 or more, further preferably 22000 or more, particularly preferably 24000 or more. On the other hand, it is preferably 50000 or less, more preferably 45000 or less, still more preferably 40000 or less, and particularly preferably 38000 or less. When the number average molecular weight of the polyether imide is within this range, the film tends to have excellent chemical resistance, heat resistance and impact resistance, and also to have excellent melt moldability because the viscosity at the time of melting is not excessively high.

The glass transition temperature of the polyether imide is preferably 140 ℃ or higher, more preferably 160 ℃ or higher, still more preferably 180 ℃ or higher, and particularly preferably 200 ℃ or higher. On the other hand, it is preferably 300 ℃ or lower, more preferably 280 ℃ or lower, and still more preferably 260 ℃ or lower. When the glass transition temperature of the polyetherimide is in this range, the film tends to have excellent heat resistance and to have excellent melt moldability because the viscosity at the time of melting is not excessively high.

The polyetherimide can be produced by a known production method. Further, commercially available products may be used. Examples of commercially available products include "Ultem" series manufactured by Sabic, inc.

The polyether ether ketone and the polyether imide are preferably main components of the film. That is, the content is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more of the entire film.

The film may contain various additives such as a heat stabilizer, an antioxidant, an ultraviolet absorber, a light stabilizer, an antibacterial/antifungal agent, an antistatic agent, a lubricant, a pigment, and a dye, within a range not to impair the effects of the present invention. Among these, from the viewpoint of the number of folding times, the present film preferably does not contain 1 mass% or more of inorganic particles such as silica, more preferably does not contain 0.5 mass% or more, still more preferably does not contain 0.1 mass% or more, and preferably does not substantially contain.

[ production method ]

The present film can be produced by a general molding method, for example, extrusion molding, injection molding, blow molding, vacuum molding, pressure-air molding, pressure molding, or the like. In each molding method, the apparatus and the processing conditions are not particularly limited, but extrusion molding is preferable from the viewpoint of productivity and thickness control, and T-die method is particularly preferable.

The method for producing the film is not particularly limited, and for example, the constituent material of the film may be obtained in the form of an unstretched film or a stretched film, and is preferably obtained in the form of an unstretched film from the viewpoint of secondary processability. The non-stretched film means: films that are not actively stretched for the purpose of controlling sheet orientation also include films that are oriented by the T-die method when drawn with casting rolls.

In the case of an unstretched film, for example, the film can be produced by melt-kneading the respective constituent materials, followed by extrusion molding and cooling. The melt kneading may be performed using a known kneader such as a single-screw extruder or a twin-screw extruder. The molding can be performed by, for example, extrusion molding using a die such as a T-die.

In the case of producing a laminated film, the laminating method is not particularly limited, and molding can be performed by any of the following methods: for example, a coextrusion method in which the resin compositions of the respective layers are coextruded and laminated; an extrusion lamination method in which each layer is formed into a film shape and laminated; the thermal compression bonding method in which the layers are formed into a film and they are thermally compressed is preferably a method of molding by coextrusion from the viewpoint of productivity. The coextrusion method comprises the following steps: the multi-manifold method in which the resin compositions of the respective layers join at the pipe head, the feed block method in which the resin compositions join at the feed block, and the like can be used.

The film is important: the surface has a surface roughness with an arithmetic average roughness (Ra) of more than 0.1 μm on at least one surface. The method for adjusting the arithmetic average roughness (Ra) is not particularly limited, and various methods such as transfer treatment such as emboss roller transfer, embossed tape transfer, embossed film transfer, blast treatment, shot blasting, etching, engraving, surface crystallization, and the like can be used. Among them, from the viewpoint of easily forming surface irregularities continuously and uniformly while extruding a molten resin in a film form, a method of roughening a surface by casting a film-form molten resin on a casting roll is preferable. In this case, the surface roughness of the resin film can be adjusted by adjusting the arithmetic average roughness (Ra) of the casting roll. The arithmetic mean roughness (Ra) of the casting roll is preferably 0.1 μm or more, more preferably more than 0.1. Mu.m, still more preferably 0.5 μm or more, and still more preferably 0.7 μm or more. Further, it is preferably 2 μm or less, more preferably 1.7 μm or less, and further preferably 1.5 μm or less.

[ film for Motor ]

The present film has a surface having a surface roughness with an arithmetic average roughness (Ra) of more than 0.1 μm on at least one surface, and both the front and back surfaces of the film are not necessarily the surface roughness described above, but from the viewpoint of insertability into a motor core or the like, it is preferably provided on both surfaces.

The film has an arithmetic average roughness (Ra) of more than 0.1 μm as measured in accordance with JIS B0601:2013 using a contact surface roughness meter. Preferably 0.15 μm or more, more preferably 0.2 μm or more, further preferably 0.3 μm or more, and particularly preferably 0.5 μm or more. If the arithmetic average roughness (Ra) of the present film is equal to or more than the lower limit value, the surface of the present film is not excessively smooth and has an appropriate roughness, so that there is an advantage that the slidability is good, and for example, the insertability into the motor core is improved, and further the problem of buckling or breaking at the time of insertion is less likely to occur.

On the other hand, the arithmetic average roughness (Ra) is preferably 2 μm or less, more preferably 1.7 μm or less, still more preferably 1.5 μm or less, and particularly preferably 1.2 μm or less. By setting the arithmetic average roughness (Ra) of the present film to be equal to or less than the upper limit value, there is an advantage that the following problems are less likely to occur: in the film conveyance during the production, slippage, misalignment, twisting, wrinkling, etc. occur on the conveyance roller, or winding misalignment of the roll occurs due to excessive slippage between the films.

The film preferably has a surface having a surface roughness with a maximum height roughness (Rz) of 1 to 10 μm, more preferably 1.5 μm or more, further preferably 2 μm or more, particularly preferably 3 μm or more, and more preferably 9 μm or less, further preferably 8 μm or less, and particularly preferably 7 μm or less, measured by a contact surface roughness meter in accordance with JIS B0601:2013, on at least one surface. When the maximum height roughness (Rz) is in this range, the insertion property into a motor core or the like is excellent, and further, buckling and breaking at the time of insertion tend to be easily prevented.

The film preferably has a surface having a surface roughness of 0.1 to 3 μm in arithmetic average height (Sa) measured by a white interference microscope on at least one surface, more preferably 0.15 μm or more, further preferably 0.25 μm or more, particularly preferably 0.3 μm or more, further preferably 2.5 μm or less, further preferably 2 μm or less, and particularly preferably 1.5 μm or less. If the arithmetic average height (Sa) is within this range, the insertion property into the motor core or the like is excellent, and further, buckling and breakage during insertion tend to be easily prevented.

The film preferably has a surface having a surface roughness of 1.5 to 30 μm in maximum height (Sz) measured by a white interference microscope on at least one surface, more preferably 2 μm or more, further preferably 3 μm or more, and on the other hand, more preferably 28 μm or less, further preferably 25 μm or less, and particularly preferably 20 μm or less. If the maximum height (Sz) is within this range, the insertion properties into the motor core and the like are excellent, and buckling and breakage during insertion tend to be easily prevented.

The compressive strength of the present film measured in accordance with JIS P8126:2015 is preferably 50 to 1300N, more preferably 60N or more, further preferably 70N or more, particularly preferably 80N or more, on the other hand, more preferably 1200N or less, further preferably 1100N or less, particularly preferably 1050N or less. When the compressive strength is in this range, buckling and breakage at the time of insertion into the motor core or the like can be prevented, and the insertion property into the motor core or the like tends to be excellent.

The thickness of the film is preferably 100 μm as measured in accordance with JIS P8115:2001, and the number of folding endurance times in the extrusion direction (MD) of the film is preferably 50 or more, more preferably 60 or more, further preferably 100 or more, and particularly preferably 150 or more. When the number of folding times is within this range, the film tends to be less likely to break even when repeatedly deformed, and to be easily formed into a tough film.

The film preferably has a tensile elastic modulus of 2500MPa or more in the extrusion direction (MD) of the film, as measured at a stretching speed of 5 mm/min and 23 ℃. More preferably 2600MPa or more, still more preferably 2800MPa or more, and particularly preferably 3000MPa or more. When the tensile elastic modulus of the present film is not less than the lower limit, the film tends to have excellent rigidity and to be easily handled even when the film is thin. The tensile modulus of elasticity is preferably 10000MPa or less, more preferably 7500MPa or less, and still more preferably 5000MPa or less. When the tensile elastic modulus is not more than the above upper limit, appropriate flexibility is imparted to the film, and insertion into a motor core or the like is facilitated, which is preferable.

The film has a coefficient of kinetic friction with a stainless steel plate, as measured in accordance with JIS K7125:1999, of preferably 0.28 or less, more preferably 0.26 or less, and still more preferably 0.25 or less, on at least one side of the film. On the other hand, it is preferably 0.01 or more, and more preferably 0.05 or more.

When the coefficient of dynamic friction between the film and the stainless steel plate is in this range, the film is excellent in insertion properties into a motor core or the like, and further tends to be easily prevented from buckling or breaking during insertion.

The film has a static friction coefficient, as measured according to JIS K7125:1999, between at least one surface of the film and a stainless steel plate of preferably 0.42 or less, more preferably 0.40 or less, still more preferably 0.38 or less, and particularly preferably 0.36 or less. On the other hand, it is preferably 0.01 or more, and more preferably 0.05 or more.

When the film has a coefficient of static friction with a stainless steel plate in this range, the film is excellent in insertion properties into a motor core or the like, and is likely to be easily prevented from buckling or breaking during insertion.

The volume porosity of the present film is preferably less than 20%, more preferably 10% or less, further preferably 5% or less, particularly preferably 1% or less, and particularly preferably substantially free of voids. Such a range of the volume porosity is preferable because the decrease in heat conduction is suppressed and the cooling efficiency tends to be further improved. The volume porosity can be calculated by using the specific gravities of the film and the raw material resin used for the film.

The thickness of the film is preferably 30 μm or more, more preferably 50 μm or more, further preferably 80 μm or more, and particularly preferably 100 μm or more. On the other hand, it is preferably 400 μm or less, more preferably 300 μm or less, still more preferably less than 300 μm, yet more preferably 250 μm or less, particularly preferably 220 μm or less, and most preferably 200 μm or less. When the thickness is not less than the lower limit, the film has sufficient insulation and rigidity, and tends to be easily prevented from current leakage during use and buckling during insertion. Further, if the thickness is equal to or less than the upper limit value, the density of the coil inserted into the motor core or the like can be increased, and the motor efficiency tends to be maintained high.

The film is a resin film having at least one of a compressive strength of 50 to 1300N and a thickness of less than 300 [ mu ] m, and a tensile elastic modulus of 2500MPa or more, and the arithmetic average roughness (Ra) of at least one surface thereof exceeds 0.1 [ mu ] m, and therefore, even a resin film having a small difference in hardness or thickness is excellent in insertion property into a motor core.

The film may be a single layer or a multilayer, and when at least one of a polyether ether ketone layer and a polyether imide layer is used, the total thickness of the polyether ether ketone layer and the polyether imide layer is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, and most preferably 100% of the entire film.

In the case of using a multilayer of a polyether ether ketone layer and a polyetherimide layer, the thickness ratio of the polyether ether ketone layer/the polyetherimide layer is preferably 1/9 to 5/5, more preferably 1/9 to 4/6, and still more preferably 2/8 to 3/7.

In the case of using a multilayer film of a polyether ether ketone layer and a polyetherimide layer, the film may contain layers other than the polyether ether ketone layer and the polyetherimide layer described above within a range not to impair the effects of the present invention.

[ use/mode of use ]

The film is excellent in insertion property into a motor core or the like by improving slidability, and therefore can be suitably used for motors for home electric appliances, audio equipment, IT equipment, communication equipment, office automation equipment, medical equipment, health management equipment, business equipment, industrial equipment, transportation equipment such as automobiles, trains, and ships, and the like. Particularly suitable for use as wedge paper or slot paper.

Examples

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

1. Manufacture of films

In examples and comparative examples, films having the blend compositions shown in table 1 below were produced using the following raw materials.

[ polyether Ether ketone ]

(A) -1: VESTAKEEP 3300G (manufactured by Daicel Evonik company, a repeating unit of (a-1), polymerization degree n =59, number average molecular weight =17000, crystal melting temperature =343 ℃, heat of crystal melting =41J/G, glass transition temperature =143 ℃)

[ polyetherimide ]

(B) -1: ultem 1000-1000 (repeating unit of (b-1), degree of polymerization n =57, number average molecular weight =34000, glass transition temperature =217 ℃ manufactured by Sabic corporation)

(B) -2: ultem CRS5001-1000 (repeating unit of (b-2), degree of polymerization n =47, number average molecular weight =27700, glass transition temperature =227 ℃ manufactured by Sabic Co.)

< example 1>

Each of (A) -1 and (B) -1 was used as a material for a polyether ether ketone layer (PEEK layer) and a polyether imide layer (PEI layer), respectively. Two single screw extruders of 40mm diameter (380 ℃ on the PEEK side and 380 ℃ on the PEI side) were used to melt them separately. The PEEK layers were divided into half in each feed block, and laminated in the feed block in the order of PEEK layer/PEI layer/PEEK layer to prepare a laminated film composed of two three layers, and the laminated film was extruded from a T die (die head temperature 380 ℃) so that the lamination ratio was 1/8/1 (thickness ratio of PEEK layer in the entire film = 20%), to obtain a laminated film having a thickness of 100 μm. Here, one surface of the film was roughened by casting on a casting roll having an arithmetic average roughness (Ra) of 1.05 μm.

< example 2>

As the raw material, (B) -2 of polyetherimide was used. The raw materials were melt-kneaded using a single-screw extruder having a diameter of 40mm, continuously extruded from a T-die, and cast on a casting roll having an arithmetic mean roughness (Ra) of 1.05. Mu.m, to obtain a single-layer film having a thickness of 100. Mu.m. The extruder temperature and the pipe head temperature at this time were both 380 ℃.

< example 3>

A single-layer film having a thickness of 200 μm was obtained in the same manner as in example 2, except that (A) -1 of polyether ether ketone was used as a raw material and that the extruder temperature and the pipe head temperature were 380 ℃.

< comparative example 1>

A laminated film having a thickness of 100 μm was obtained in the same manner as in example 1, except that the arithmetic average roughness (Ra) of the casting roll was 0.07. Mu.m.

< reference example 1>

A laminated film was obtained in the same manner as in example 1, except that polyetherimide (B) -2 was used as a raw material for the polyetherimide layer (PEI layer) and the thickness of the laminated film was 300 μm.

< reference example 2>

A laminated film was obtained in the same manner as in example 1 except that polyetherimide (B) -2 was used as a raw material for the polyetherimide layer (PEI layer), the arithmetic average roughness (Ra) of the casting roll was 0.07. Mu.m, and the thickness of the laminated film was 300. Mu.m.

The films of examples, comparative examples and reference examples obtained by the above-described methods were evaluated for the arithmetic average roughness (Ra), the maximum height roughness (Rz), the arithmetic average height (Sa), the maximum height (Sz), the compressive strength, the folding endurance, the tensile modulus, the coefficient of dynamic friction, the coefficient of static friction and the insertability, which are described below. The direction in which the film-like molded article is extruded from the T-die is referred to as the "longitudinal direction" of the film, and the direction perpendicular thereto in the film plane is referred to as the "transverse direction" of the film.

The evaluation results are shown in table 1.

2. Evaluation of film

(1) Arithmetic average roughness (Ra), maximum height roughness (Rz)

The film was measured on the roughened surface side using a contact surface roughness meter Surf code ET4000A (sakaguchi research corporation) under the conditions of a stylus tip radius of 0.5mm, a measurement length of 8.0mm, a reference length of 8.0mm, a cut-off value of 0.8mm, and a measurement speed of 0.2 mm/sec in the longitudinal direction of the film, and an arithmetic average roughness (Ra) and a maximum height roughness (Rz) were calculated.

(2) Arithmetic mean height (Sa), maximum height (Sz)

The surface of the film on the roughened side was measured using a white interference microscope (manufactured by BRUKER) under conditions of an eyepiece magnification of 1.0 times, an objective magnification of 20 times, and a measurement region of 235. Mu. M in the vertical direction by 313. Mu.m in the horizontal direction, and subjected to smoothing processing using a Gaussian function, and then an arithmetic mean height (Sa) and a maximum height (Sz) were calculated.

(3) Compressive strength

First, in a test piece supporting tool including a block (outer frame) having a cylindrical recess and a detachable disk (inner frame), the disk is attached to the block to form a circular groove, and a test piece is held in the groove to support the test piece. The concave portion of the block had an inner diameter of 49.8mm and a depth of 6.35mm, and the outer diameter of the disk was 49.6mm in the case of a film thickness of 100 μm, 49.5mm in the case of a film thickness of 200 μm, and 49.3mm in the case of a film thickness of 300 μm. In addition, the thickness of the disc was 6.35mm.

The test piece was punched out into a strip shape by using a punching blade having a width of 12.7mm (longitudinal direction of the film) and a length of 157mm (transverse direction of the film), the test piece was rolled up into a circle along the longitudinal direction, and when the ends overlapped when the test piece was placed in the groove of the test piece supporting tool, an excess amount was cut off.

After the test piece was placed on the test piece support jig, the test piece was run until the test piece was flattened by using a precision universal tester Autograph AG-X (manufactured by Shimadzu corporation), and the maximum compressive force at the time of flattening was measured as the compressive strength.

(4) Number of times of folding endurance

For each thin film having a thickness of 100 μm, the number of folding endurance was measured in the longitudinal direction of the thin film using an MIT bending fatigue tester (manufactured by Toyo Seiki Seisaku-Sho Ltd.) in accordance with JIS P8115: 2001. In example 3 and reference examples 1 and 2, films having a thickness of 100 μm for measuring the folding endurance were separately produced and measured in the same manner, with the same lamination ratio.

(5) Modulus of elasticity in tension

For each film, a short test piece having a length of 400mm and a width of 5mm was prepared, and the tensile elastic modulus (MPa) was measured in the machine direction of the film using a tensile compression tester 205 type (manufactured by INTESCO corporation) under the conditions of an atmospheric temperature of 23 ℃, an inter-jig distance of 300mm, and a tensile speed of 5 mm/min.

(6) Coefficient of dynamic friction and coefficient of static friction with stainless steel plate

The test piece was cut out from the roughened surface of the film. With reference to JIS K7125:1999, the surface of the test piece on the roughened side was kept in contact with the stainless steel plate for 15 seconds before the start of the test, and then measured in the longitudinal direction under the following conditions to evaluate the coefficient of dynamic friction and the coefficient of static friction with the stainless steel plate.

An apparatus: plastic film sliding tester (INTESCO Co., ltd.)

A slide: total mass 200g (contact area is a square with 63mm on one side)

Contact area: 40cm ²

Test speed: 100 mm/min

Temperature: 23 +/-2 deg.C

Relative humidity: 50% +/-10%

(7) Insertion property

A test piece having a width of 235mm (transverse direction of the film) and a length of 210mm (longitudinal direction of the film) was cut out from the film, and the end of the film was fixed with a tape, thereby producing a cylindrical test piece 1 having an inner diameter of 75mm and a length of 210mm as shown in FIG. 1. The test piece 1 was produced such that the inside of the cylinder was a roughened surface (when used in an actual product, the motor copper wire side is also a roughened surface in general).

A plastic lid 2 having a length of 66mm, an inner diameter of a cylinder part of 75mm and a head diameter of 99mm was attached to one end of a test piece 1, and placed on an iron plate 3. Next, a weight 4 made of an iron material having a bottom surface of 30mm × 75mm and a mass of 1057g was set on the cylindrical test piece 1 at the other end of the test piece 1, and the weight 4 was fixed by a fixing tool 5 so as not to move in the longitudinal direction of the test piece 1. The test piece 1 was pressed in the longitudinal direction (arrow direction) from the end to which the lid member 2 was attached, and the case where the test piece 1 was moved by 50mm or more was regarded as insertion property × (very good), and the case where buckling or breaking occurred before the movement by 50mm or more was regarded as insertion property × (bad).

[ Table 1]

The films obtained in examples 1 to 3 had an arithmetic average roughness (Ra) of more than 0.1. Mu.m, and were excellent in insertion properties. This effect is achieved by the film of the present invention having a surface with a large arithmetic average roughness (Ra) disposed on at least one surface. Further, a motor obtained by using such a film having excellent insertion property is excellent in motor performance.

On the other hand, comparative example 1 had an arithmetic average roughness (Ra) of 0.1 μm or less, and the coefficient of dynamic friction and the coefficient of static friction were large, and the insertability was also poor.

Both reference examples 1 and 2 were films having high compressive strength and large thickness. Therefore, the following steps are carried out: in such a thin film, the problem of insertability is not easily caused even if the arithmetic average roughness (Ra) exceeds 0.1 μm (reference example 1) or falls below 0.1 μm (reference example 2).

In the above embodiments, specific embodiments of the present invention have been described, but the above embodiments are merely illustrative and are not to be construed as limiting. Various modifications apparent to those skilled in the art should be considered to fall within the scope of the present invention.

Industrial applicability

The film for a motor of the present invention is excellent in insertability into a motor core or the like, and therefore, is widely used for motors for home electric appliances, audio equipment, IT equipment, communication equipment, office automation equipment, medical equipment, health management equipment, business equipment, industrial equipment, transportation equipment such as automobiles, trains, and ships, and the like.

Description of the symbol mark

1. Test piece

2. Cover material

3. Iron plate

4. Weight(s)

5. Fixing tool

Claims

1. A film for a motor, which is a resin film having a tensile modulus of elasticity of 2500MPa or more and a compressive strength of 50 to 1300N, and at least one surface of which has an arithmetic average roughness (Ra) of more than 0.1 [ mu ] m.

2. A film for a motor, which is a resin film having a tensile modulus of elasticity of 2500MPa or more and a thickness of less than 300 μm, and at least one surface of which has an arithmetic average roughness (Ra) of more than 0.1 μm.

3. The film for a motor according to claim 1 or 2, wherein the arithmetic average roughness (Ra) is 2 μm or less.

4. The film for a motor according to any one of claims 1 to 3, wherein an arithmetic mean height (Sa) of at least one surface of the film is 0.1 to 3 μm.

5. The film for the motor according to any one of claims 1 to 4, wherein the maximum height roughness (Rz) of at least one surface of the film is1 to 10 μm.

6. The film for a motor according to any one of claims 1 to 5, wherein the maximum height (Sz) of at least one surface of the film is 1.5 to 30 μm.

7. The film for the motor according to any one of claims 1 to 6, wherein at least 1 selected from the group consisting of polyether ether ketone and polyetherimide is contained as a material of the film.

8. The film for a motor according to any one of claims 1 to 7, wherein a coefficient of dynamic friction between at least one surface of the film and the stainless steel plate is 0.28 or less.

9. The film for a motor according to any one of claims 1 to 8, wherein a static friction coefficient between at least one surface of the film and the stainless steel plate is 0.42 or less.

10. The film for a motor according to any one of claims 1 to 9, which has a folding endurance of 50 or more times when the thickness is 100 μm.

11. The film for a motor according to any one of claims 1 to 10, which is a wedge-shaped paper.

12. A film for an electrical machine according to any one of claims 1 to 10 which is a slot paper.

13. A motor using the film for a motor according to any one of claims 1 to 12.

14. The method for producing a film for a motor according to any one of claims 1 to 12, wherein the film is produced by extrusion molding using a casting roll having an arithmetic average roughness (Ra) of 0.1 to 2 μm.