JP6431316B2 - Insulation sheet for motor - Google Patents

Description

  The present invention relates to an insulating sheet for a motor, and more particularly to an insulating sheet provided in a motor that conveys a refrigerant.

  Conventionally, a motor serving as a driving force for home appliances, industrial equipment, etc. is interposed between a slot insulation sheet interposed between a core and a winding coil in a stator core slot, and between winding coils of different phases. Various insulating sheets such as an interphase insulating sheet, a wedge sheet that closes the opening of the slot groove from the inside, and a bus bar insulating sheet that insulates the bus bar are provided.

This type of motor insulation sheet is provided in the motor in a shape suitable for each purpose. For example, in the case of the slot insulation sheet, a strip longer than the slot groove is generally used. In order to correspond to the inner surface shape of the slot groove, a bent sheet is used so that the cross section has a U-shape.
In addition, the slot insulating sheet is generally provided in the motor in such a manner that both end portions protrude outward from both end surfaces of the stator core in the rotation axis direction of the motor. There is a process called “cuff fold” that turns back to the opposite side of the winding coil.

  Therefore, the insulating sheet for motors is required not only to have excellent insulating properties but also to have excellent flexibility so as not to cause cracking due to bending or the like.

By the way, in recent years, alternative chlorofluorocarbons having a low ozone depletion coefficient have been adopted as refrigerants in refrigeration / refrigeration equipment, air conditioning equipment, etc., and alternative chlorofluorocarbon refrigerants containing difluoromethane such as HFC32 and HFC410a have been widely adopted. ing.
In the air conditioner, the refrigerant is circulated by a hermetic compressor, and a motor serving as the conveyance power of the refrigerant in the hermetic compressor is used in a state of being in contact with the refrigerant.
In addition, a compressor that uses this type of alternative chlorofluorocarbon refrigerant in a refrigeration cycle tends to have a higher temperature during operation than a compressor that uses chlorofluorocarbon refrigerant.
Therefore, heat resistance is required for members constituting this type of compressor, and as shown in Patent Document 1 below, a polyethylene terephthalate film has been conventionally used as an insulating sheet for a motor.

JP-A-9-100300

Polyester resin films such as polyethylene terephthalate resin films (PET films) usually contain low molecular weight components such as monomers and oligomers, so when used in motor insulating sheets used in situations where they come into contact with alternative chlorofluorocarbon refrigerants, There is a risk that low molecular weight components may be extracted by alternative chlorofluorocarbon refrigerants.
In addition, a film called “low oligomer product” having a low molecular weight component content lower than that of a general polyester resin film is commercially available.
However, such low molecular weight components have a plasticizer function with respect to the polyester resin.
For this reason, films called “low oligomer products” tend to be inferior in properties such as tensile elongation at break compared to general-purpose films, and simply using a film with a low content of low molecular weight components for motor insulating sheets. In the bending process, there is a possibility that cracks and cracks are likely to occur in the bent portion.
In addition, even if it is a general purpose polyester resin film containing a low molecular weight component to some extent, if the low molecular weight component is extracted by a refrigerant as described above, the flexibility may be lost.
The insulating sheet for a motor after the low molecular weight component has been extracted by the refrigerant in this way may cause cracks or cracks in the bent portion due to a temperature cycle accompanying operation / stop of the motor, vibration during operation, etc. is there.

For this reason, the conventional motor insulating sheet is not suitable for use in a state where the insulating sheet for the alternative chlorofluorocarbon refrigerant is in contact with the alternative chlorofluorocarbon refrigerant.
This invention makes it a subject to provide the insulating sheet for motors suitable for being used in the state which touches the said alternative CFC refrigerant in the motor which conveys an alternative CFC refrigerant in view of the above points.

As a result of intensive studies by the present inventor, it is possible to suppress the stress concentration at the bent portion by providing the motor insulating sheet with a laminated structure in which two polyester resin films are bonded together by a resin composition. It was found that it is effective for suppressing cracks and cracks.
In addition, the present inventor made a polyester resin in an intermediate layer between the polyester resin films formed by the resin composition by making the resin composition for bonding the polyester resin film low in elasticity to the polyester resin film. The point which can suppress that a co-crack with a film arises was discovered, and it came to complete this invention.

  That is, the present invention is an insulating sheet for a motor provided in a motor that conveys an alternative chlorofluorocarbon refrigerant in order to solve the above-described problem, and two polyester resin films are bonded by a thermoplastic resin composition, It has a laminated structure of three or more layers including two film layers made of the polyester resin film and an intermediate layer made of the thermoplastic resin composition, and is used in a state where the film layer is in contact with the alternative chlorofluorocarbon refrigerant. And the insulating sheet for motors whose said thermoplastic resin composition is lower elastic modulus than the said polyester resin film is provided.

  According to the present invention, an insulating sheet for a motor that exhibits excellent heat resistance and hydrolysis resistance while being used in a situation where it comes into contact with an alternative chlorofluorocarbon refrigerant, and is less likely to be cracked or cracked at a bent portion or the like. Can be obtained.

The schematic front view which showed the lamination sheet for forming the insulating sheet for motors of one Embodiment. The schematic sectional drawing which showed the laminated structure of the laminated sheet shown in FIG. Schematic which showed an example of the manufacturing method of a lamination sheet. Schematic front view illustrating a method of forming an insulating sheet for a motor by bending a laminated sheet The schematic perspective view which showed one use condition of the insulating sheet for motors (slot insulating sheet). The schematic perspective view which showed the method of the cut-through test.

Hereinafter, an embodiment of the present invention relating to an insulating sheet for motors will be described by taking a slot insulating sheet as an example.
The slot insulating sheet of this embodiment is provided in a motor for transporting a refrigerant that performs heat transport in a refrigeration / refrigeration system or an air conditioning system, and is used in a state of being in contact with the refrigerant.
The slot insulating sheet of this embodiment is used in a state in which a flat laminated sheet is bent to have a three-dimensional shape.
First, a laminated sheet used for forming a slot insulating sheet will be described with reference to FIGS.

The laminated sheet 1 of the present embodiment has a three-layer structure as shown in the figure, and the shape in a front view is a horizontally long rectangle.
Specifically, the laminated sheet 1 is formed by bonding two polyester resin films with a thermoplastic resin composition, and from the two film layers 10 and 20 made of the polyester resin film and the thermoplastic resin composition. It has a three-layer structure with the intermediate layer 30.
As described above, the slot insulating sheet of the present embodiment has a three-layer structure.
Therefore, when the slot insulating sheet of this embodiment is compared with the thing of the same thickness, the ratio for which the polyester resin film accounts is reduced compared with the conventional thing formed entirely with the polyester resin film.
That is, in the slot insulating sheet of this embodiment, the content of the low molecular weight substance derived from the polyester resin film is reduced as compared with the conventional slot insulating sheet.
Therefore, the slot insulating sheet of the present embodiment uses the thermoplastic resin composition having a lower content of low molecular weight material than the polyester resin film for forming the intermediate layer 30, thereby containing the low molecular weight material as a whole sheet. The amount will be reduced compared to conventional slot insulation sheets.

A film layer 10 (hereinafter also referred to as “first film layer 10”) disposed on one side of both surfaces of the laminated sheet 1 and a film layer 20 (hereinafter referred to as “second film layer”) disposed on the other side. 20 ”), the higher the thickness, the higher electrical insulation can be exhibited with respect to the slot insulation sheet.
On the other hand, when the thickness of the film layers 10 and 20 is increased, the laminated sheet 1 not only increases the content of the low molecular weight substance, but also reduces the workability in the bending process. There is a risk of making it difficult to manufacture.
Therefore, the film layers 10 and 20 are preferably formed of a polyester resin film having a predetermined thickness excellent in electrical insulation.
More specifically, the film layers 10 and 20 have a volume resistivity defined by JIS C2151-2006 (A method, b condition (standard condition B in Table 1 of IEC60212: 23 ° C., 50% RH)) of 1 ×. It is preferably formed of a polyester resin film having a thickness of 10 μm to 100 μm and having an electric insulation of 10 ¹² Ω · cm or more.
In addition, the upper limit value of the volume resistivity of the polyester resin film is usually about 1 × 10 ¹⁸ Ω · cm.

Examples of the polyester resin film include a polyethylene terephthalate resin film (PET), a polybutylene terephthalate resin film (PBT), a polytrimethylene terephthalate resin film (PTT), a polyethylene naphthalate resin film (PEN), and a polybutylene naphthalate resin. A film (PBN), a polylactic acid resin film (PLA), etc. are mentioned.
These polyester resin films may be so-called “low oligomer products” or so-called “general-purpose products”.
The polyester resin film may be subjected to a surface treatment so as to improve the adhesiveness with the thermoplastic resin composition constituting the intermediate layer 30.

Among them, various grades related to oligomer content and surface treatment are available at relatively low cost, and the design can be easily changed according to the required characteristics for motor insulation sheets, as well as heat resistance and hydrolysis resistance. The polyester resin film forming the first film layer 10 and the second film layer 20 is preferably either a polyethylene terephthalate resin film or a polyethylene naphthalate resin film.
In particular, the polyethylene naphthalate resin film is preferably used for forming at least one of the first film layer 10 and the second film layer 20 in that it has high heat resistance and hydrolysis resistance.

It is important that the intermediate layer 30 is formed of a resin composition having a lower elastic modulus than the polyester resin film.
Moreover, it is preferable that the said intermediate | middle layer 30 is comprised with a resin composition with few generation | occurrence | production amounts of the extract by an alternative CFC refrigerant | coolant compared with the polyester resin film which comprises a film layer.
That is, examples of the resin constituting the intermediate layer 30 include a polyamide resin (PA6, PA66, PA610, PA46, PA6T, PA9T, etc.), a polyphenylene ether resin (m-PPE, PPE / PA alloy), a polysulfone resin, a polysulfone resin, and the like. Examples include ether sulfone resins and polyetherimide resins.

The “elastic modulus” when comparing the polyester resin film and the thermoplastic resin composition constituting the intermediate layer 30 means a tensile elastic modulus, for example, a value obtained as follows. To do.
(Measurement method of elastic modulus)
The “elastic modulus” can be obtained in accordance with the “tensile elastic modulus” measurement method in JIS K7161, for example, a sample having a width of 15 mm × a length of 250 mm is prepared and pulled so that the distance between chucks is 180 mm. It can be calculated as follows using the initial linear portion of the “tensile stress-strain curve” obtained by setting the tester and conducting a tensile test at a tensile speed of 200 mm / min.

Elastic modulus = Δσ / Δε

(However, “Δε” is a “strain difference” between two points in the straight section of the “tensile stress-strain curve”, specifically 1%. “Δσ” is a difference between the two points. "Stress difference".)

In addition, when the polyester resin film from which a tensile elasticity modulus differs is used for the 1st film layer 10 and the 2nd film layer 20, the said intermediate | middle layer 30 should just be a elasticity modulus lower than at least one, and with respect to both It is preferable that the elastic modulus is low.
The polyester resin film preferably has a modulus of elasticity of 3000 MPa to 6000 MPa as described above, and the thermoplastic resin composition preferably has a modulus of elasticity of 1500 MPa to 3000 MPa.
Moreover, it is preferable that the elasticity modulus of the said thermoplastic resin composition when the elasticity modulus of the said polyester resin film is 100% is 25%-80%.
When a polyester resin film having different tensile elastic modulus is used for the first film layer 10 and the second film layer 20, the intermediate layer 30 has an elastic modulus of 25% to 80% with respect to at least one. It is preferable that the elastic modulus is 25% to 80% with respect to both.

The intermediate layer 30 preferably has a volume resistivity of 1 × 10 ¹² Ω · cm to 1 × 10 ¹⁸ Ω · cm, and is formed of a polyamide resin composition in order to exhibit heat resistance comparable to that of a polyester resin film. It is preferable to make it. The intermediate layer 30 is preferably formed to a thickness of 10 μm to 100 μm by the polyamide resin composition.
The polyamide resin composition forming the intermediate layer 30 preferably has heat resistance equal to or higher than that of the polyester resin film forming the film layers 10 and 20 and is excellent in toughness.
The polyamide resin composition forming the intermediate layer 30 may contain an aromatic polyamide resin from the viewpoint of heat resistance.
However, if the intermediate layer 30 is made of only an aromatic polyamide resin as the resin to be contained in the polyamide resin composition, there is a possibility that excellent toughness may not be exhibited, and sufficient adhesion with the film layers 10 and 20 is sufficient. There is a possibility that the characteristic will not be exhibited.
For this reason, the polyamide resin composition preferably contains not only an aromatic polyamide resin but also a phenoxy resin having an epoxy group at the molecular end.

As the aromatic polyamide resin, for example, an aromatic polyamide that is polymerized by dehydration condensation of a diamine and a dicarboxylic acid and that uses an aromatic diamine or dicarboxylic acid can be used.
Examples of the diamine include aliphatic diamine, alicyclic diamine, and aromatic diamine. Examples of the aliphatic diamine or alicyclic diamine include those represented by the following general formula (1). It is done.

In addition, “R ¹ ” in the above formula (1) represents an aliphatic or alicyclic alkyl represented by C _n H _2n (n = 6 to 12).

As this diamine, it is particularly preferable to use a mixture of hexamethylene diamine and 2-methylpentamethylene diamine because they can exhibit excellent characteristics even at high temperatures.
Moreover, xylylenediamine etc. can be used as aromatic diamine.

  As the dicarboxylic acid, aliphatic dicarboxylic acid, alicyclic dicarboxylic acid, aromatic dicarboxylic acid and the like can be used. Examples of the aliphatic dicarboxylic acid or alicyclic dicarboxylic acid include the following general formula (2). What is represented.

In the above formula, “R ² ” represents an aliphatic or alicyclic alkyl represented by C _n H _2n (n = 4 to 25).

Examples of the aromatic dicarboxylic acid include terephthalic acid, methyl terephthalic acid, and naphthalenedicarboxylic acid.
As the aromatic dicarboxylic acid, it is particularly preferable to employ a mixture of terephthalic acid and isophthalic acid in order to make the intermediate layer 30 exhibit excellent characteristics even at high temperatures.
In the aromatic polyamide resin, these diamines and dicarboxylic acids may be used alone or in a plurality of types.
Furthermore, the aromatic polyamide resin may be a modified product containing components other than diamine and dicarboxylic acid, if necessary.

  Examples of the phenoxy resin having an epoxy group (hereinafter, also referred to as “epoxy group-containing phenoxy resin”) include those represented by the following general formula (3).

In the general formula (3), “R ³ ” and “R ⁴ ” represent a terminal group, and at least one is an epoxy group.

As this phenoxy resin provided with the epoxy group, those having a weight average molecular weight (Mw) of 10,000 to 80,000 can be used.
The weight average molecular weight (Mw) is measured by the GPC method, for example, under the following conditions.
Standard reagent: TSK standard polystyrene (A-500, A-2500, F-1, F-4,
F-20, F-128; manufactured by Tosoh Corporation)
Solvent: THF
Column: GF-1G7B + GF-7MHQ (manufactured by Showa Denko)

In addition, the weight average molecular weight (Mw) of the phenoxy resin is 15000 in that it has good compatibility with the aromatic polyamide resin and can be easily dispersed, and the flowability at the time of heat melting of the polyamide resin composition can be improved. It is preferably ˜60000.
The reason why the weight average molecular weight of the phenoxy resin is preferably in the above range is that it is difficult to adopt a method using a T-die as described later as a method for producing the laminated sheet 1 of the present embodiment.
That is, when the weight-average molecular weight of the phenoxy resin is less than 15000, the polyamide resin composition is melted by heat to bond the polyester resin film, and bubbles are generated when trying to extrude the molten resin from a T die or the like. There is a possibility that voids are generated in the intermediate layer 30 due to being easily caught.
On the other hand, when the weight average molecular weight of the phenoxy resin exceeds 50000, the flowability of the molten resin is insufficient, and it may be difficult to extrude from a T die or the like.
Therefore, the weight average molecular weight of the phenoxy resin is preferably within the above range.

The epoxy group-containing phenoxy resin has an epoxy equivalent because it can more effectively suppress the flowability of the polyamide resin composition and can improve the mechanical properties of the polyamide resin composition when mixed with an aromatic polyamide. It is preferable that it is 10,000 g / eq or more and 30000 g / eq or less.
In addition, the said epoxy equivalent intends the value calculated | required by JISK7236.

In the polyamide resin composition of the present embodiment, the ratio of the epoxy group-containing phenoxy resin in the total of the aromatic polyamide resin and the epoxy group-containing phenoxy resin is preferably 30% by mass or more and 50% by mass or less.
It is preferable that the blending amount of the epoxy group-containing phenoxy resin blended in the polyamide resin composition is in such a range, when the ratio is less than 30% by mass, the flowability of the polyamide resin composition is suppressed. This is because if the ratio exceeds 50% by mass, the polyamide resin composition may not exhibit sufficient properties such as excellent heat resistance and moist heat resistance of the aromatic polyamide resin. .
In addition to such points, in the case where physical properties such as elongation and tensile strength of the polyamide resin composition can be enhanced, the ratio of the epoxy group-containing phenoxy resin is more than 35% by mass and 45% by mass or less. preferable.

The polyamide resin composition can contain components other than the aromatic polyamide resin and the epoxy group-containing phenoxy resin, and can further contain other resins and various additives other than the resin.
Other components that can be included in the polyamide resin composition in addition to the aromatic polyamide resin and the epoxy group-containing phenoxy resin include, for example, alkylphenol resins, alkylphenol-acetylene resins, xylene resins, coumarone-indene resins, terpenes Resin, tackifiers such as rosin, bromine compounds such as polybromodiphenyl oxide and tetrabromobisphenol A, halogenated flame retardants such as chlorinated paraffin and perchlorocyclodecane, phosphorous esters such as phosphate esters and halogenated phosphate esters Flame retardants, hydrated metal compounds such as aluminum hydroxide and magnesium hydroxide, flame retardants such as antimony trioxide and boron compounds, phenolic, phosphorus and sulfur antioxidants, heat stabilizers, light stabilizers UV absorber, sliding , Pigments, crosslinking agents, crosslinking aids, silane coupling agents, titanate coupling agents, and other common plastic compounding chemicals, silica, clay, calcium carbonate, aluminum oxide, magnesium oxide, boron nitride, silicon nitride, nitriding Examples include inorganic fillers such as aluminum.

The polyamide resin composition contains 0.1 to 5 parts by mass of montmorillonite having a particle size of nanometer level or 0.6 mm Kevlar with respect to a total of 100 parts by mass of the aromatic polyamide resin and the epoxy group-containing phenoxy resin. High strength can be achieved.
In the polyamide resin composition, triallyl isocyanate, tetra-n-butoxy titanium, or tris (2,3-epoxypropyl) isocyanate is added in a total of 100 parts by mass of the aromatic polyamide resin and the epoxy group-containing phenoxy resin. On the other hand, it is possible to increase the strength by containing 0.1 to 5 parts by mass.
This triallyl isocyanate is commercially available from Nippon Kasei Co., Ltd. under the trade name “TAIC”, and tetra-n-butoxy titanium is commercially available from Nippon Soda Co., Ltd. under the trade name “B-1”. As tris (2,3-epoxypropyl) isocyanate, a commercially available product under the trade name “TEPIC-G” from Nissan Chemical Co., Ltd. can be used.

If the polyamide resin composition contains a large amount of a low molecular weight substance as another component, the amount of the extract from the intermediate layer 30 by the alternative CFC refrigerant may be increased.
Further, in such a case, the polyamide resin composition may contaminate an alternative chlorofluorocarbon refrigerant with a low molecular weight substance and cause a decrease in function in the heat transport.
Accordingly, the polyamide resin composition preferably contains a total of 95% by mass or more of the aromatic polyamide resin and the epoxy group-containing phenoxy resin, and a total of 98% by mass or more of the aromatic polyamide resin and the epoxy group-containing phenoxy resin. It is more preferable that the total amount of the aromatic polyamide resin and the epoxy group-containing phenoxy resin is 99% by mass or more.
That is, it is preferable that the components of the polyamide resin composition are substantially only an aromatic polyamide resin and an epoxy group-containing phenoxy resin.

  In producing the laminated sheet 1, the polyamide resin composition is in a state of a molten mixture by a general kneading device such as a kneader, a pressure kneader, a kneading roll, a Banbury mixer, a single screw extruder, a twin screw extruder, or the like. By making it, it can utilize for bonding of the two polyester resin films.

More specifically, in order to form the laminated sheet 1, for example, a manufacturing method using equipment as shown in FIG. 3 can be employed.
The equipment illustrated in FIG. 3 includes a first roll 10R in which a polyester resin film for forming the first film layer 10 is wound up in a roll shape, and a long belt-like polyester resin film from the first roll 10R. The first roll 10R is fed as a first raw material sheet 10s, and a second roll 20R in which a polyester resin film for forming the second film layer 20 is wound into a roll is provided. A second sending machine 20x for sending a long belt-like polyester resin film as a second raw material sheet 20s is provided.
The facility also includes an extruder 50 for extruding a molten polyamide resin composition into a sheet between the first raw material sheet 10s and the second raw material sheet 20s, and a molten polyamide resin composition. A pair of squeezing rollers 61 and 62 for correcting the thickness of a laminate (laminated sheet) sandwiched between two polyester resin films (first and second raw material sheets) and cooling the polyamide resin composition are provided. A diaphragm device 60 is provided.
Further, the facility includes a winder 1x that winds the long strip-shaped laminated sheet 1s having a predetermined thickness by the squeezing device 60.

When producing a laminated sheet with the said equipment, the said intermediate | middle layer 30 will be formed with the polyamide resin composition of the molten state extruded from the said extruder 50. FIG.
The thickness of the intermediate layer 30 is usually determined by the distance between the squeezing rollers 61 and 62.
That is, the thickness of the laminated sheet 1 s after passing through the squeezing rollers 61 and 62 is normally the width of the gap provided between the squeezing rollers 61 and 62.
When the width of the gap between the squeezing rollers 61 and 62 is “T0”, the thickness of the first raw material sheet 10s is “T1”, and the thickness of the second raw material sheet 10s is “T2”, the thickness of the intermediate layer 30 is “T0”. − (T1 + T2) ”.
Therefore, the first film layer 10, the second film layer 20, and the intermediate layer 30 constituting the laminated sheet 1 are composed of two polyester resin films used as a raw material sheet and the two polyester resin films as a polyamide. It can adjust to desired thickness by the condition setting at the time of bonding with a resin composition.

The laminated sheet 1 produced as described above is bent so that a crease is formed at a position indicated by a broken line in FIG. 4 to obtain a slot insulating sheet 100 as shown in FIG. be able to.
The slot insulating sheet 100 shown in FIG. 5 has a body portion 101 accommodated in the slot groove of the stator core of the motor, and the end surface of the core in the motor rotation axis direction when the body portion 101 is accommodated in the slot groove. Folded portions 102 and 103 projecting outward are provided.
The slot insulating sheet 100 is formed with the body portion 101 so that a cross-sectional shape when cut along a plane orthogonal to the rotation axis direction of the motor is a “U” shape. The folded portions 102 and 103 are provided in a so-called “cuff fold” state on one end side and the other end side of the body portion 101, respectively.
The folded portions 102 and 103 are portions formed by folding the laminated sheet 1 so that creases are formed along the broken lines “a1” and “a2” in FIG. 4, respectively.
That is, the slot insulating sheet 100 shown in FIG. 5 is, for example, a broken line opposite to the folded direction after the laminated sheet 1 shown in FIG. 4 is folded in the same direction along “a1” and “a2”. It is produced by bending the laminated sheet 1 at an angle of about 90 degrees along “b1” and “b2”.

In a conventional slot insulating sheet made of only a polyester film, cracks and cracks are likely to occur at the fold, and careful work is required for such folding processing.
On the other hand, in the slot insulating sheet 100 of the present embodiment, the intermediate layer 30 is formed of a polyamide resin composition having excellent toughness and excellent adhesion to the first film layer 10 and the second film layer 20. The stress concentration that the first film layer 10 and the second film layer 20 receive at the fold during the bending process is alleviated by the presence of the intermediate layer 30, and cracks and cracks are prevented from being generated.
Therefore, although it has higher heat resistance than PET film, etc., it is harder than PET film, so it is easy to cause cracking during bending, and it can be bent into a complicated shape like a slot insulation sheet alone. A PEN film or the like that has been difficult to employ as a material for forming a motor insulating sheet can be suitably used as a material for forming the first film layer 10 and the second film layer 20.

Even if the PET film has a tendency to be inferior in tensile elongation at break than a general grade film such as a low oligomer product having an oligomer content of 1% by mass or less, the first film layer 10 and the second film layer 20 It can be suitably used as a forming material.
In addition, about oligomer content, such as PET film, for example, after the film sample of the magnitude | size about 5 cm in a square is wash | cleaned with methanol, this film sample is dried for 1 hour in a 160 degreeC hot-air oven, and is initial stage. After obtaining the mass (M1 (g)), the film sample was extracted with boiling xylene (about 400 ml) using a Soxhlet extractor or the like for 48 hours, and the mass (M2 (g)) of the film sample after extraction was calculated. It can be determined by measuring and calculating the ratio of mass reduction (M1-M2) to initial mass (M1) ((M1-M2) / M1).
Here, the mass (M2 (g)) of the film sample after extraction cannot be accurately determined unless the xylene used for extraction is sufficiently removed from the film sample and measured. It is preferable to measure the sample after washing the sample with water and wiping off the xylene adhering to the surface, followed by further drying in a hot air oven at 160 ° C. for 8 hours and allowing to cool in a desiccator.

  For this reason, the slot insulating sheet 100 according to the present embodiment is used in a high-temperature environment in a motor for transporting an alternative chlorofluorocarbon refrigerant such as a hermetic compressor in a refrigeration / freezing device or an air conditioning device, and the first film layer 10 In addition, when the second film layer 20 is used in a state of being in contact with the alternative chlorofluorocarbon refrigerant, insulation reliability can be ensured and contamination of the refrigerant can be prevented.

As this alternative chlorofluorocarbon refrigerant, for example, HFC23 (R23), HFC32 (R32), HFC125 (R125), HFC134a (R134a), HFC143a (R143a), HFC152a (R152a), HFC410a (R410a: HFC32 / HFC125 = 50) / 50), HFC407c (R407c: HFC32 / HFC125 / HFC134a = 23/25/52) and the like.
Among these, the slot insulating sheet of the present embodiment can exhibit the above functions more remarkably in applications where it comes into contact with an alternative chlorofluorocarbon refrigerant containing difluoromethane (HFC32).

  Such a function is exhibited not only when the slot insulating sheet includes only three layers of the first film layer 10 / the intermediate layer 30 / the second film layer 20, but for example, the first film layer 10 having a laminated structure of four or more layers with one or more other layers outside, and having a laminated structure of four or more layers with one or more other layers outside the second film layer 20 The same is true for those having a laminated structure of five or more layers, each having one or more other layers outside the first film layer 10 and the second film layer 20.

  In addition, this function is exhibited not only when the motor insulation sheet is a slot insulation sheet that is cuff-folded, but also when the slot insulation sheet is simply folded into a “U” shape. The same applies to the case where the motor insulating sheet is other than the slot insulating sheet, such as the interphase insulating sheet, the bus bar insulating sheet, and the wedge insulating sheet for closing the opening of the slot.

That is, the motor insulating sheet of the present invention is not limited to the slot insulating sheet used in a specific form.
In other words, motor insulating sheets other than those described above are also within the intended scope of the present invention.

  Further, even if the matter is not exemplified in the above, as long as the effect of the present invention is not significantly impaired, the known technical matters in the structure and manufacturing method of the motor insulating sheet are the same as those of the present invention. It can be used for motor insulation sheets.

EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.
First, samples as shown in the following table were prepared and evaluated as described later.
In addition, No. About 1, 2, and 6, it produced by the method as shown in FIG.
That is, a resin composition heated and melted between two belt-like PEN (PET) films was extruded, and the two PEN (PET) films were bonded together with this resin composition.
No. For 3 and 4, commercially available resin films were used as they were.
Furthermore, no. No. 5 was prepared by forming an adhesive layer on both sides of a PET film and sandwiching it with PEN films from both sides.

(Evaluation)
(Oligomer extraction amount)
For each sample, the oligomer content was measured by the method described above.

(Moisture and heat resistance test)
A plurality of 15 mm × 250 mm strip samples were cut out from each sample, and a pressure cooker test (PCT) was performed under the conditions of 120 ° C., relative humidity 100%, and atmospheric pressure 0.2 MPa.
For the initial strip-shaped sample and the strip-shaped sample after PCT (50 hours, 100 hours, 150 hours, 200 hours), a tensile test based on JIS K7127 (tensile speed 200 mm / min, marked line distance 100 mm, chuck distance 100 mm) ).
The initial tensile strength was taken as 100%, and the residual ratio of tensile strength after PCT was determined.

(Cut-through test: see Fig. 6)
A 20 mm × 100 mm strip sample (TP) was cut out from each sample.
A stainless steel plate (SP) larger than the strip sample (TP) was prepared, and this was placed flat, and the strip sample (TP) was placed so as not to protrude from the steel plate (SP). .
A straight knife (KC) was set on the upper side of the strip-shaped sample (TP) so that the cutting edge (R = 0.1 mm) faced downward.
Further, the knife (KC) was set so that the cutting edge crossed the strip sample (TP) in the width direction at the center in the length direction of the strip sample (TP).
The cutting edge was applied to the upper surface of the strip-shaped sample (TP), a downward load (F) was applied, and the maximum load required to tear the strip-shaped sample (TP) was measured.

  The above evaluation results are shown in Table 2 below.

  From the above evaluation results, it can be seen that according to the present invention, a motor insulating sheet suitable for being used in a state of being in contact with the alternative chlorofluorocarbon refrigerant in a motor for conveying the alternative chlorofluorocarbon refrigerant is provided.

  1: laminated sheet, 10: first film layer, 20: second film layer, 30: intermediate layer, 100: slot insulating sheet (insulating sheet for motor)

Claims (4)

An insulating sheet for a motor provided in a motor for conveying an alternative chlorofluorocarbon refrigerant,
Two polyester resin films are bonded by a thermoplastic resin composition, and a laminated structure of three or more layers including two film layers made of the polyester resin film and an intermediate layer made of the thermoplastic resin composition. has, Ri low modulus der than and the thermoplastic resin composition used in a state in which the film layer is in contact with the CFC refrigerant the polyester resin film,
Insulating sheet for the intermediate layer Ru nonporous layer der motor.   The polyester resin film is a polyethylene naphthalate resin film or a polyethylene terephthalate resin film having an oligomer content of 1% by mass or less, and the thermoplastic resin composition is an aromatic polyamide resin and an epoxy group at the molecular end. The motor insulating sheet according to claim 1, which is a polyamide resin composition containing a phenoxy resin.   The insulating sheet for motor according to claim 1, wherein the alternative chlorofluorocarbon refrigerant contains difluoromethane.   4. The slot insulation sheet used in a slot of a stator core of the motor and used for insulation between the stator core and a winding coil accommodated in the slot. 5. The insulation sheet for motors as described.

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