JP7287012B2 - Insulating film for motor and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thin-walled insulating film for motors, which is excellent in insertability by improving slipperiness, and more particularly to a film that can be suitably used as wedge paper or slot paper.

Conventionally, in motors that drive home appliances and industrial equipment, slot paper and slot groove openings are closed from the inside as an insulating film interposed between the core and the winding coil in the slots in the stator core. Wedge paper is provided.
These insulating films are usually incorporated by being inserted into slots through openings in the end face of the stator core.

In recent years, the performance of motors has improved, and there is a demand for compact and highly efficient motors. For that purpose, there is a method of increasing the lamination factor of the wound coil by thinning the insulating film, but along with this, excellent insertability of the insulating film such as wedge paper or slot paper is required.
Furthermore, since heat tends to accumulate inside the motor due to miniaturization, there are cases where the stator core or rotor core is directly immersed in the coolant.

As such an insulating film, aramid paper, which has a surface that is more slippery than ordinary resin films, etc., or a laminate in which aramid paper is laminated with a resin film via an adhesive, etc. Widely used.

However, aramid paper tends to form pinholes and the like when it is thinned compared to resin films and the like, and it is difficult to reduce the thickness while suppressing deterioration in insulation reliability.
Moreover, the aramid paper has less stiffness than a resin film of the same thickness and is easily buckled.
In addition, in the case of laminates of aramid paper and resin film, only products with aramid paper of 50 μm or more are commercially available.
Furthermore, the fibers of the aramid paper may become fuzzy when cut or inserted, and may remain inside the motor as foreign matter, causing wear on the rotor and significantly degrading motor performance.

Patent Literature 1 discloses an insulating sheet having a predetermined surface roughness, and states that the insulating sheet can have slipperiness equivalent to that of aramid paper.

JP 2009-055678 A

However, in Patent Document 1, the arithmetic mean roughness (Ra) of the insulating sheet is 0.05 μm or more and 0.1 μm or less. Although it is stated that there is, it is not disclosed quantitatively.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an insulating film for motors which is excellent in insertability and thin in thickness by improving slipperiness. be.

As a result of intensive studies, the inventors of the present invention have succeeded in obtaining an insulating film for motors that can solve the above-described problems of the prior art, and have completed the present invention.

That is, the present invention is an insulating film for motors having at least one surface with an arithmetic mean roughness (Ra) of 0.15 μm or more and 1.50 μm or less.

According to the present invention, a resin film having at least one surface with an arithmetic mean roughness (Ra) of 0.15 μm or more and 1.50 μm or less is used. With such surface roughness, the coefficient of dynamic friction with the SUS plate is low, so that excellent insertability can be obtained.
Therefore, it is possible to provide a thin insulating film for motors.
Furthermore, since the resin film does not contain fibers, it is possible to suppress the generation of foreign matter during insertion into the slot, thereby maintaining the performance of the motor.

The insulating film for motors of the present invention (hereinafter sometimes referred to as "the present film") has a surface having a surface roughness with an arithmetic mean roughness (Ra) of 0.15 μm or more and 1.50 μm or less. It is a resin film provided.

Note that both the front and back surfaces of the resin film may not necessarily have the above surface roughness, and only the surface side that contacts the winding coil or the inner wall surface has the above roughness, for example, one side has the arithmetic mean roughness (Ra) is 0.15 μm or more and 1.50 μm or less, and a resin film having a smooth surface on the other side can also be used.
A detailed description will be given below.

Although the resin film used for this film is not particularly limited, for example, engineering plastics with heat resistance of 100 degrees or more and chemical resistance to refrigerants such as oil are preferable as motors are becoming smaller and more efficient, and super engineering plastics. is more preferable.
Among them, polyetheretherketone or polyetherimide is preferable.

In addition, a resin film having a two-layer structure formed by laminating different resins, for example, polyetheretherketone is used on one side and polyetherimide is used on the other side, or three or more layers A resin film or the like having a laminated structure of can also be used as the insulating sheet.

[Polyether ether ketone]
Polyetheretherketone has a repeating unit (a-1) represented by the following structural formula (1). The repeating unit (a-1) has two ether groups and one ketone group.

The lower limit of the total number (degree of polymerization) of the repeating units (a-1) of the polyetheretherketone is preferably 10 or more, more preferably 20 or more. On the other hand, the upper limit is preferably 500 or less, and more preferably 100 or less. If the total number (degree of polymerization) of the repeating units (a-1) in the polyetheretherketone resin is in the range, the insulating film for motors of the present invention is excellent in chemical resistance, heat resistance and impact resistance. Melt moldability is excellent because the viscosity when melted is not too high.

The lower limit of the heat of crystal fusion of polyetheretherketone is preferably 20 J/g or more, more preferably 25 J/g or more, and even more preferably 30 J/g or more. On the other hand, the upper limit is preferably 60 J/g or less, more preferably 55 J/g or less, and even more preferably 50 J/g or less. As long as the heat of crystal melting of the polyetheretherketone is within the range, the insulating film for motors of the present invention is excellent in heat resistance and, in addition, requires only a small amount of thermal energy during melt-molding, resulting in excellent melt-moldability.

The lower limit of the crystal melting temperature of polyetheretherketone is preferably 300° C. or higher, more preferably 320° C. or higher, and even more preferably 340° C. or higher. On the other hand, the upper limit is preferably 400° C. or lower, more preferably 380° C. or lower, and even more preferably 360° C. or lower. As long as the crystal melting temperature of the polyetheretherketone is in the range, the insulating film for motors of the present invention is excellent in heat resistance and also excellent in melt moldability because the viscosity is not too high when melted.

The lower limit of the glass transition temperature of polyetheretherketone is preferably 120° C. or higher, more preferably 140° C. or higher. On the other hand, the upper limit is preferably 200° C. or lower, more preferably 180° C. or lower. As long as the glass transition temperature of the polyetheretherketone is in the range, the insulating film for motors of the present invention is excellent in heat resistance and excellent in melt moldability because the viscosity is not too high when melted.

Polyetheretherketone can be produced by a known production method, and a commercially available product can also be used. Examples of commercially available products include "VICTREX PEEK" series manufactured by Victrex, "KetaSpire" series manufactured by Solvay, and "VESTAKEEP" series manufactured by Daicel-Evonik.

[Polyetherimide]
Polyetherimide has a repeating unit (b-1) represented by the following structural formula (2) or a repeating unit (b-2) represented by the following structural formula (3).

In general, polyetherimides are classified according to their bonding modes, that is, meta-bonds and para-bonds, and have different mechanical properties and heat resistance.

The total number (degree of polymerization) of the repeating units (b-1) or (b-2) of the polyetherimide is preferably 10 or more, more preferably 20 or more, as the lower limit. On the other hand, the upper limit is preferably 1000 or less, more preferably 500 or less. As long as the total number (degree of polymerization) of the repeating units (b-1) or (b-2) of the polyetherimide is in the range, the insulating film for motors of the present invention is excellent in heat resistance and has a viscosity when melted. Since it is not too high, it is excellent in melt moldability.

The lower limit of the glass transition temperature of polyetherimide is preferably 140° C. or higher, more preferably 160° C. or higher, and even more preferably 180° C. or higher. On the other hand, the upper limit is preferably 300° C. or lower, more preferably 280° C. or lower, and even more preferably 260° C. or lower. As long as the glass transition temperature of the polyetherimide is within this range, the insulating film for motors of the present invention is excellent in heat resistance and also excellent in melt moldability since the viscosity is not too high when melted.

Polyetherimide can be produced by a known production method. Moreover, a commercial item can also be used. Examples of commercially available products include the "Ultem" series manufactured by Savik.

[Insulating film for motors]
This film is measured using a contact surface roughness meter, and the lower limit of the arithmetic mean roughness (Ra) is 0.15 μm or more, preferably 0.30 μm or more, and 0.50 μm or more. It is more preferable to have If the arithmetic mean roughness (Ra) of the film is less than 0.15 μm, the surface of the film is too smooth and slipperiness is poor, so the dynamic friction coefficient with the SUS plate is rather increased, and the motor core is affected. This may lead to insertability and, in turn, buckling or breakage during insertion.
On the other hand, the upper limit is 1.50 μm or less, preferably 1.20 μm or less, and more preferably 1.00 μm or less. If the arithmetic mean roughness (Ra) of the film exceeds 1.50 μm, the surface of the film is too rough, and the coefficient of dynamic friction with the SUS plate increases, and the coefficient of dynamic friction with the SUS plate increases. It is easy to insert into the body, and it may lead to buckling or breakage during insertion.

The film preferably has a coefficient of dynamic friction with a SUS plate of 0.250 or less, more preferably 0.200 or less, and 0.180 or less, measured in accordance with JIS K7125:1999. is more preferred. On the other hand, the lower limit is not particularly limited, but is preferably 0.010 or more, more preferably 0.050 or more.
If the coefficient of dynamic friction between the film and the SUS plate is in the range, the insertability into the motor core is excellent, and buckling and breakage during insertion can be prevented. By providing at least one surface with an arithmetic mean roughness (Ra) of 0.15 μm or more and 1.50 μm or less, the above characteristics can be satisfied.

The lower limit of the thickness of the present film is preferably 50 µm or more, more preferably 100 µm or more, still more preferably 150 µm or more, and particularly preferably 200 µm or more. On the other hand, the upper limit is preferably 500 µm or less, more preferably 450 µm or less, even more preferably 400 µm or less, and particularly preferably 350 µm or less. If the thickness is 50 μm or more, the film has sufficient insulation and rigidity, and can prevent current leakage during use and buckling during insertion. Also, if the thickness is 500 μm or less, the density of coils inserted into the motor core can be increased, and the motor efficiency can be maintained high.

In addition, the present film may contain various additives such as heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, antibacterial and antifungal agents, antistatic agents, lubricants, pigments, and dyes, as long as they do not impair the effects of the present invention. Additives may be included.

[Production method]
The film can be produced by general molding methods such as extrusion molding, injection molding, blow molding, vacuum molding, air pressure molding, and press molding. In each molding method, the apparatus and processing conditions are not particularly limited, but from the viewpoint of productivity and thickness control, extrusion molding, particularly the T-die method, is preferable.

The method for producing the insulating film for motors of the present invention is not particularly limited, but for example, the constituent material of the film can be obtained as a non-stretched or stretched film, and from the viewpoint of secondary workability, it can be obtained as a non-stretched film. preferable. The unstretched film is a film that is not actively stretched for the purpose of controlling the orientation of the sheet, and includes a film that is oriented when it is taken up by a cast roll in the T-die method.

In the case of a non-stretched film, for example, it can be produced by melt-kneading each constituent material, followed by extrusion molding and cooling. A known kneader such as a single-screw or twin-screw extruder can be used for melt-kneading. Molding can be carried out, for example, by extrusion using a mold such as a T-die.

When manufacturing a laminated film, a coextrusion method in which the resin composition of each layer is coextruded and laminated, an extrusion lamination method in which each layer is formed into a film and laminated, each layer is formed into a film, and these are heated. Although any thermocompression bonding method may be used for molding, co-extrusion molding is preferred from the viewpoint of productivity. The co-extrusion method includes a multi-manifold method in which the resin compositions of each layer are joined through a spinneret, a feed block method in which the resin compositions are joined through a feed block, and the like, and any of them may be used.

It is important that at least one surface of the insulating film for motors of the present invention has a surface roughness with an arithmetic average roughness (Ra) of 0.15 μm or more and 1.5 μm or less. As a method for adjusting the arithmetic mean roughness (Ra), in extrusion molding, there is a method in which a molten resin is heated to a predetermined temperature or higher, solidified on cast rolls, and shaped. At this time, the surface roughness of the resin film can be adjusted by adjusting the arithmetic surface roughness of the cast roll. The arithmetic average roughness (Ra) of the cast roll is preferably 0.15 μm or more and 1.5 μm or less.

[Usage/Mode of use]
Since the insulating film for motors of the present invention is excellent in insertability by improving the slipperiness, it is used in household appliances, audio equipment, IT equipment, communication equipment, OA equipment, medical equipment, healthcare equipment, business equipment, industrial equipment, It can be suitably used for motors for transportation equipment such as automobiles, railroads, and ships. In particular, it can be suitably used 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 to these.

1. Production of Films In Examples and Comparative Examples, the following raw materials were used to produce films having the composition shown in Table 1 below.

<Polyether ether ketone>
(A)-1: VESTAKEEP 3300G (manufactured by Daicel-Evonik, repeating unit of (a-1), crystal melting temperature = 343°C, glass transition temperature = 143°C)

<Polyetherimide>
(B)-1: Ultem 1000-1000 (manufactured by Savik, repeating unit of (b-1), glass transition temperature = 217°C)
(B)-2: Ultem CRS5001-1000 (manufactured by Savik, repeating unit of (b-2), glass transition temperature = 227°C)

(Example 1)
Polyetheretherketone (A)-1 was used as a raw material. The raw materials were melt-kneaded using a Φ40 mm single-screw extruder, continuously extruded through a T-die, and cast onto a roll having a surface roughness (Ra) of 1.05 μm to obtain a film. At this time, the temperature of the extruder for polyetheretherketone, the temperature of the extruder, and the temperature of the die were all set to 380°C.
A film having a thickness of 300 μm was prepared, and the surface roughness and dynamic friction coefficient were evaluated. These results are shown in Table 1.

(Example 2)
(A)-1 was used as the raw material for the polyetheretherketone layer (PEEK layer), and (B)-1 was used as the raw material for the polyetherimide layer (PEI layer). These were melted separately using two Φ40mm extruders. The PEEK layer is divided into halves in the feed block, laminated in the feed block in the order of PEEK layer/PEI layer/PEEK layer, extruded from a T-die to form a laminated film having a two-kind three-layer structure, and laminated. A laminate film was obtained by casting on a cast roll having a surface roughness (Ra) of 1.05 μm so that the ratio was 1/8/1 (the thickness ratio of the PEEK layer in the entire film=20%). Table 1 shows the evaluation results.

(Example 3)
A sample was prepared in the same manner as in Example 2, except that (B)-2 was used as the raw material for the polyetherimide layer (PEI layer). Table 1 shows the evaluation results.

(Example 4)
Example 1 except that polyetherimide (B)-1 was used as a raw material instead of polyetheretherketone (A)-1, and the surface roughness (Ra) of the cast roll was changed to 0.32 μm. A sample having a thickness of 175 μm was prepared in the same manner as in the above. Table 1 shows the evaluation results.

(Example 5)
A sample was prepared in the same manner as in Example 1, except that polyetherimide (B)-2 was used as a raw material instead of polyetheretherketone (A)-1. Table 1 shows the evaluation results.

(Example 6)
A sample was prepared in the same manner as in Example 5, except that the surface roughness (Ra) of the cast roll was changed to 0.32 μm. Table 1 shows the evaluation results.

(Comparative example 1)
A sample was prepared in the same manner as in Example 3, except that the surface roughness of the cast roll was changed to 0.07 μm. Table 1 shows the evaluation results.

2. Evaluation of Film Each film produced in the above examples and comparative examples was evaluated and measured for various items as follows. Here, the "longitudinal" of the film refers to the direction in which the film-like molded article is extruded from the T-die, and the "horizontal" is the direction orthogonal to this in the plane of the film.

(1) Surface roughness For each film, using a contact surface roughness tester Surf Coder ET4000A, the stylus tip radius was 0.5 mm, the measurement length was 8.0 mm, the reference length was 8.0 mm, and the cutoff value was 0.5 mm. Measurement was performed in the longitudinal direction under the conditions of 8 mm and a measurement speed of 0.2 mm/sec, and the arithmetic mean roughness (Ra) was calculated.

(2) Coefficient of dynamic friction with SUS plate
Each film was measured in the longitudinal direction using a plastic film slip tester (Intesco) in accordance with JIS K7125:1999 to evaluate the coefficient of dynamic friction with a SUS plate (stainless steel plate).

The films obtained in Examples 1 to 6 had a surface roughness (Ra) of 0.15 μm or more and a dynamic friction coefficient of 0.25 or less, showing excellent slipperiness. This effect is due to the film of the present invention having a layer of high surface roughness. Moreover, regardless of the type and thickness of the resin in the outermost layer, it can be said that the slipperiness is improved as the surface roughness increases.
On the other hand, in Comparative Example 1, the surface roughness was less than 0.15 μm, and the dynamic friction coefficient was large, so the slipperiness was also inferior.

Claims (10)

A film having a surface with an arithmetic mean roughness (Ra) of 0.29 μm or more and 1.5 μm or less on at least one side, the film containing polyetheretherketone, and a coefficient of dynamic friction between the surface and a stainless steel plate is 0.250 or less .
However, it is a production method for molding a highly heat-resistant and highly slidable film using a molding material obtained from polyetheretherketone resin, polyetherimide resin, and fluororesin, and is represented by the chemical formula [Chemical Formula 1]. A polyether ether ketone resin having a repeating unit and a polyether imide resin having a repeating unit represented by the chemical formula [Chemical 2] and having a glass transition point of 200 ° C. or higher are polyether ether ketone in the composition mass ratio A molding material obtained by adding 1 to 30 parts by mass of a fluororesin to 100 parts by mass of a resin composition containing 5 to 70% by mass of a resin and 95 to 30% by mass of a polyetherimide resin is prepared by melt-kneading, and molded. A highly heat-resistant and highly slidable film is continuously extruded from the die of the extruder using the material, and the extruded highly heat-resistant and highly slidable film is sandwiched between the pressing roll and the cooling roll. to form fine unevenness on the surface of the highly heat resistant and highly slidable film, and the arithmetic mean roughness (Ra) of the unevenness is 0.20 to 5.0 μm. Excludes films obtained by a method for producing highly slidable films.

2. The insulating film for motors according to claim 1 , having a thickness of 50 [mu]m or more and 500 [mu]m or less. 3. The insulating film for motors according to claim 1, comprising a polyetheretherketone layer and a polyetherimide layer. 4. The method for producing the insulating film for motors according to any one of claims 1 to 3, wherein the insulating film is produced by extrusion molding. A method for producing a film having at least one surface with an arithmetic mean roughness (Ra) of 0.29 μm or more and 1.5 μm or less , and having a coefficient of dynamic friction of 0.250 or less between the surface and a stainless steel plate. A method for producing an insulating film for a motor, characterized in that the film is produced by extrusion molding.
However, it is a production method for molding a highly heat-resistant and highly slidable film using a molding material obtained from polyetheretherketone resin, polyetherimide resin, and fluororesin, and is represented by the chemical formula [Chemical Formula 1]. A polyether ether ketone resin having a repeating unit and a polyether imide resin having a repeating unit represented by the chemical formula [Chemical 2] and having a glass transition point of 200 ° C. or higher are polyether ether ketone in the composition mass ratio A molding material obtained by adding 1 to 30 parts by mass of a fluororesin to 100 parts by mass of a resin composition containing 5 to 70% by mass of a resin and 95 to 30% by mass of a polyetherimide resin is prepared by melt-kneading, and molded. A highly heat-resistant and highly slidable film is continuously extruded from the die of the extruder using the material, and the extruded highly heat-resistant and highly slidable film is sandwiched between the pressing roll and the cooling roll. to form fine unevenness on the surface of the highly heat resistant and highly slidable film, and the arithmetic mean roughness (Ra) of the unevenness is 0.20 to 5.0 μm. Except for the method for producing a highly slidable film.

6. The method for producing an insulating film for motors according to claim 5, which contains polyetheretherketone or polyetherimide. The method for producing an insulating film for motors according to any one of claims 4 to 6, wherein the film is produced using a cast roll having an arithmetic mean roughness (Ra) of 0.29 µm or more and 1.5 µm or less. A wedge paper using an insulating film for a motor having at least one surface with an arithmetic mean roughness (Ra) of 0.29 μm or more and 1.5 μm or less and a coefficient of dynamic friction between the surface and a stainless steel plate of 0.250 or less. .
However, it is a production method for molding a highly heat-resistant and highly slidable film using a molding material obtained from polyetheretherketone resin, polyetherimide resin, and fluororesin, and is represented by the chemical formula [Chemical Formula 1]. A polyether ether ketone resin having a repeating unit and a polyether imide resin having a repeating unit represented by the chemical formula [Chemical 2] and having a glass transition point of 200 ° C. or higher are polyether ether ketone in the composition mass ratio A molding material obtained by adding 1 to 30 parts by mass of a fluororesin to 100 parts by mass of a resin composition containing 5 to 70% by mass of a resin and 95 to 30% by mass of a polyetherimide resin is prepared by melt-kneading, and molded. A highly heat-resistant and highly slidable film is continuously extruded from the die of the extruder using the material, and the extruded highly heat-resistant and highly slidable film is sandwiched between the pressing roll and the cooling roll. to form fine unevenness on the surface of the highly heat resistant and highly slidable film, and the arithmetic mean roughness (Ra) of the unevenness is 0.20 to 5.0 μm. Excludes films obtained by a method for producing highly slidable films.

A slot paper using an insulating film for a motor having at least one surface with an arithmetic average roughness (Ra) of 0.29 μm or more and 1.5 μm or less and a coefficient of dynamic friction between the surface and a stainless steel plate of 0.250 or less. .
However, it is a production method for molding a highly heat-resistant and highly slidable film using a molding material obtained from polyetheretherketone resin, polyetherimide resin, and fluororesin, and is represented by the chemical formula [Chemical Formula 1]. A polyether ether ketone resin having a repeating unit and a polyether imide resin having a repeating unit represented by the chemical formula [Chemical 2] and having a glass transition point of 200 ° C. or higher are polyether ether ketone in the composition mass ratio A molding material obtained by adding 1 to 30 parts by mass of a fluororesin to 100 parts by mass of a resin composition containing 5 to 70% by mass of a resin and 95 to 30% by mass of a polyetherimide resin is prepared by melt-kneading, and molded. A highly heat-resistant and highly slidable film is continuously extruded from the die of the extruder using the material, and the extruded highly heat-resistant and highly slidable film is sandwiched between the pressing roll and the cooling roll. to form fine unevenness on the surface of the highly heat resistant and highly slidable film, and the arithmetic mean roughness (Ra) of the unevenness is 0.20 to 5.0 μm. Excludes films obtained by a method for producing highly slidable films.

A motor using the insulating film for a motor according to any one of claims 1 to 3, the wedge paper according to claim 8 , or the slot paper according to claim 9 .