JP7466465B2 - Insulating material for rotating electrical machines and rotating electrical machines - Google Patents

Description

The present invention relates to an insulating material for rotating electric machines that can maintain the insulation properties of motors (electric motors) and generators and prevent short circuits, etc., and to a rotating electric machine.

In recent years, due to growing awareness of environmental issues, the development of transportation that runs on motors such as electric vehicles (EVs), hybrid vehicles (HVs), hybrid electric vehicles (HEVs), plug-in hybrid vehicles (PHVs), fuel cell vehicles (FCVs), electric vehicles, or electric locomotives has been in the spotlight. The motors used in these transportation systems, which are rotating electrical machines, have been made smaller, more powerful, and more efficient, but this has led to a rapid increase in the trend toward higher voltages and currents. Therefore, the insulating sheets used in such motors are required to have higher electrical and mechanical properties, lower water absorption, and excellent heat resistance than ever before.

Examples of insulating sheets used in motors include: (1) slot material that is manually inserted between the inner wall surface of a stator slot and the conductive winding housed in the slot to ensure insulation between the conductive winding and the stator core (see Patent Document 1); (2) wedges that are attached to block the entrance of the stator core to prevent the conductive winding from falling off (see Patent Document 2); and (3) interphase insulating sheets that are interposed between conductive windings of different phases in three-phase AC motors, etc. (see Patent Document 3).

Specific insulating sheets that have been proposed and implemented for use in motors include fully aromatic aramid resin fiber sheets (manufactured by DuPont Teijin Advanced Paper: product name: Nomex paper), insulating paper made of polyether ether ketone fibers (see Patent Document 4), resin fiber sheets made of polyester resin fiber sheets such as polyethylene terephthalate resin fibers and polybutylene naphthalate resin fibers, polyester films made of polyethylene terephthalate resin films and polyethylene naphthalate resin films, polyphenylene sulfide resin films made of biaxially oriented polyphenylene sulfide resin films (see Patent Document 5) and non-oriented polyphenylene sulfide resin sheets (see Patent Document 6), or resin sheets.

JP 2018-74672 A Japanese Patent Application Laid-Open No. 7-222387 JP 2012-170248 A Japanese Patent Application Laid-Open No. 1-298300 Japanese Patent Application Laid-Open No. 55-35459 Japanese Patent Application Laid-Open No. 56-34426

The insulating sheets used in conventional motors, such as those made of fully aromatic aramid resin fiber sheets, polyether ether ketone fibers, and polyester resin fiber sheets, have high motor oil impregnation and slipperiness, and are expected to improve workability when inserting them into the slots.

However, in recent years, there has been a demand for motors to be compact, high-output, and highly efficient, and so there is a demand to increase the proportion of conductive windings. In this regard, resin fiber sheets have poorer electrical properties than resin sheets, so it is more difficult to make them thinner than resin sheets, and so it is more difficult to increase the proportion of conductive windings than resin sheets.

In addition, resin fiber sheets have a high water absorption rate, so their electrical properties, such as dielectric properties and dielectric strength, are easily affected by environmental changes in temperature and humidity, and are highly frequency-dependent, which is undesirable. Furthermore, if the resin fiber sheet has through holes such as pinholes, the electrical properties (dielectric strength) at the locations where the through holes are formed will decrease. Furthermore, if the resin fiber sheet has internal voids (air bubbles), partial discharges may occur at low voltages at the locations where the bubbles are present.

On the other hand, polyester-based insulating sheets such as polyethylene terephthalate resin and polyethylene naphthalate resin have poor heat resistance and are classified as Class E (maximum allowable temperature: 120°C) in the heat resistance classification of IEC Publication 85 (1984). Therefore, they cannot be used for motors of electric vehicles, hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles, etc., which require Class F (maximum allowable temperature: 155°C) in the same heat resistance classification.

In addition, although biaxially oriented polyphenylene sulfide resin films and non-oriented polyphenylene sulfide resin films satisfy the heat resistance classifications of IEC Publication 85 (1984), Class F (maximum allowable temperature: 155°C) and Class H (maximum allowable temperature: 180°C), their tensile elongation at break is small and their toughness is poor, so when they are processed into slot material or wedges and inserted into slots, problems arise in that they break, crack, or tear.

In addition, in the past, in order to improve the electrical insulation of fully aromatic aramid fiber sheets, aramid-polyester laminates obtained by directly thermally bonding aramid paper formed into a paper-like shape mainly from aramid fibrids and aramid short fibers to a polyester-based resin film (see Japanese Patent No. 4607826), and laminates obtained by bonding an aramid fiber sheet or aramid fiber paper to a polyphenylene phenylene sulfide resin film without using an adhesive have been developed and proposed (see Japanese Patent No. 4402734, see JP 2011-140151 A).

However, although aramid-polyester film laminates can improve the insulating properties of aramid paper, the heat resistance of the polyester film is poor, making it difficult to use in Class F. In addition, the hydrolysis resistance is also poor, making it difficult to say that it is suitable for use in high-temperature, high-humidity environments. Furthermore, polyester film has problems with chemical resistance.

In addition, a laminate consisting of an aramid fiber sheet or aramid fiber paper and a polyphenylene sulfide resin film can improve the toughness of the non-oriented polyphenylene sulfide resin sheet or polyphenylene sulfide resin film, but the adhesion between the aramid fiber sheet or aramid fiber paper and the polyphenylene sulfide resin film is insufficient, resulting in delamination and problems with adhesion.

The present invention has been made in consideration of the above, and aims to provide an insulating material for rotating electric machines and a rotating electric machine that can increase the occupancy rate of conductive windings and also provide excellent electrical insulation properties, low dielectric properties, high rigidity, high toughness, low water absorption, high heat resistance, chemical resistance, etc.

After extensive research, the inventors focused on the excellent properties of polyarylene ether ketone resins and completed the present invention. Polyarylene ether ketone (also called aromatic polyether ketone, PAEK) resins are thermoplastic crystalline resins that have excellent electrical properties, mechanical properties, heat resistance, chemical resistance, radiation resistance, hydrolysis resistance, low water absorption, and recyclability. In view of these excellent properties, polyarylene ether ketone resins have been proposed for use and are being used in a wide range of fields, including the automotive field, energy field, semiconductor field, medical field, and aerospace.

In order to solve the above problems, the present invention provides a polyarylene ether ketone resin sheet that is melt extruded to prevent short circuits in rotating electrical machines ,
The polyarylene ether ketone resin sheet has a relative crystallinity of 95% or more and 100% or less , a thickness of 100 μm or more and 750 μm or less, and a glass transition point of 150° C. or more and 180° C. or less ,
The electrical properties of the polyarylene ether ketone resin sheet are a dielectric breakdown strength in silicone oil of 9 kV or more, a dielectric breakdown strength per unit thickness in silicone oil of 50 kV/mm or more and 400 kV/mm or less , a relative dielectric constant at a frequency of 1 GHz of 1.5 or more and 3.1 or less , and a dielectric dissipation factor of 0.0001 or more and 0.007 or less,
The mechanical properties of the polyarylene ether ketone resin sheet are a tensile modulus of 3500 N/mm2 ^or more and 4700 N/mm2 ^or less , a maximum tensile strength of 100 N/mm2 ^or more, and a tensile elongation at break of 200% or more ;
The polyarylene ether ketone resin sheet is characterized in that its water absorption rate at 23°C is 0.7% or less .

The insulating polyarylene ether ketone resin sheet is preferably a polyether ether ketone resin sheet.

In addition, a substantially U-shaped polyarylene ether ketone resin sheet that houses a conductive winding can be inserted into a slot formed in at least one of the stator and rotor of a rotating electric machine, and this polyarylene ether ketone resin sheet can be used as an insulating wall member interposed between the slot and the conductive winding.

Furthermore, a polyarylene ether ketone resin sheet having a thickness of 50 μm or more and 1000 μm or less can be used as a partition member that partitions the inside of the wall member into a plurality of sections.
Furthermore, a polyarylene ether ketone resin sheet having a thickness of 50 μm or more and 1000 μm or less can be used as a covering member that covers the opening of the wall member.

In order to solve the above problems, the present invention is characterized in that a rotating electric machine includes the insulating material for a rotating electric machine according to claim 1, 2, or 3 .

Here, the polyarylene ether ketone resin sheet in the claims does not particularly matter whether it is transparent, opaque, translucent, unstretched, uniaxially stretched, or biaxially stretched. This polyarylene ether ketone resin sheet includes both polyarylene ether ketone resin sheets and polyarylene ether ketone resin films. In addition, the polyarylene ether ketone resin sheet may be one sheet or multiple sheets.

When manufacturing insulating material for rotating electrical machines, a molding material containing polyarylene ether ketone resin is melt-kneaded, and the molding material is extruded into a polyarylene ether ketone resin sheet using a die of a molding machine, and the polyarylene ether ketone resin sheet is cooled by contacting it with a cooling roll. Rotating electrical machines include at least various motors (electric motors) and generators. The slots may be recessed into the stator or rotor of the rotating electrical machine, or may be recessed into both the stator and the rotor.

According to the present invention, a polyarylene ether ketone resin sheet having excellent electrical properties is selected and its thickness is set to 100 μm or more and 750 μm or less , so that the insulating material can be made thinner and the occupancy rate of the conductive winding can be increased. In addition, since the polyarylene ether ketone resin sheet of the insulating material has a low water absorption rate, the electrical properties such as the dielectric properties and dielectric strength are not easily affected by environmental changes such as temperature and humidity, and it is possible to prevent the frequency dependence from becoming large.

In addition, the insulating polyarylene ether ketone resin sheet has excellent electrical insulation properties, which can suppress the deterioration of electrical properties and reduce the risk of partial discharge occurring at low voltages. In addition, the polyarylene ether ketone resin sheet has excellent heat resistance and recyclability, making it possible to use it for rotating electric machines such as electric vehicles, hybrid vehicles, plug-in hybrid vehicles, and fuel cell vehicles. Furthermore, the polyarylene ether ketone resin sheet has excellent mechanical properties, so even if it is inserted as a wall member into the slot of a rotating electric machine, it can suppress the breakage, cracking, and tearing of the wall member.

According to the present invention, since the polyarylene ether ketone resin sheet is adopted as an insulating material for a rotating electric machine, it is possible to obtain excellent electrical properties, mechanical properties, heat resistance, chemical resistance, radiation resistance, hydrolysis resistance, low water absorption, recyclability, and the like. In addition, since the relative crystallinity of the polyarylene ether ketone resin sheet is 95% or more and 100% or less , and the heat resistance is sufficient, it is possible to prevent deformation, cracking, or dimensional changes caused by heat generated by a motor. In addition, since the rigidity of the polyarylene ether ketone resin sheet is sufficient, it is possible to eliminate the risk of buckling when inserted into a slot of a core. In addition, since the thickness of the polyarylene ether ketone resin sheet is 100 μm or more and 750 μm or less , it is possible to increase the occupancy rate of the conductive winding while preventing the deterioration of the electrical insulation of the polyarylene ether ketone resin sheet.
In addition, since the glass transition point of the polyarylene ether ketone resin sheet is 150°C or more and 180°C or less, it is expected that the heat resistance can be maintained, and when the polyarylene ether ketone resin sheet is extruded, it is possible to reduce costs without requiring special extrusion molding equipment. In addition, it is possible to eliminate the risk of limiting the extruder that can be used. In addition, the electrical properties of the polyarylene ether ketone resin sheet are a dielectric breakdown strength of 9 kV or more in silicone oil, a dielectric breakdown strength per unit thickness in silicone oil of 50 kV/mm or more and 400 kV/mm or less , a relative dielectric constant at a frequency of 1 GHz of 1.5 to 3.1 , and a dielectric loss tangent of 0.0001 to 0.007, so that dielectric breakdown due to surge voltage and thermal decomposition due to self-heating of the polyarylene ether ketone resin sheet are prevented, and it is easy to realize high current and high voltage for rotating electric machines.

Furthermore, in electric vehicles, hybrid vehicles, plug-in hybrid vehicles, and the like, which require higher driving voltages, insulation breakdown due to surge voltages and insulation deterioration of the conductive windings due to partial discharges can lead to a reduction in the voltage withstand life of the rotating electric machine, posing a major problem. However, by selecting a polyarylene ether ketone resin sheet having the above-mentioned electrical properties, it becomes easy to ensure a high level of insulation in the motors of electric vehicles, hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles, and the like.
In addition, since the polyarylene ether ketone resin sheet has a maximum tensile strength of 100 N/mm2 ^or more and a tensile elongation at break of 200% or more, sufficient toughness is ensured in the polyarylene ether ketone resin sheet, and it is possible to prevent problems such as breakage, cracking, and tearing when the polyarylene ether ketone resin sheet is inserted as a wall member into a slot of a rotating electric machine. Furthermore, since the water absorption rate of the polyarylene ether ketone resin sheet at 23°C is 0.7% or less , it is possible to maintain excellent electrical properties even if the rotating electric machine is used in a high humidity environment.

According to the invention described in claim 2, since the polyarylene ether ketone resin sheet is a polyether ether ketone resin sheet, the moldability and availability of the resin sheet can be improved, and the manufacturing cost can be reduced.

According to the invention described in claim 3 , a polyarylene ether ketone resin sheet having a thickness of 50 μm or more and 1000 μm or less is formed into at least a substantially U-shape and used as a wall member interposed between the slot and the conductive winding, thereby making it possible to increase the occupancy rate of the conductive winding and also to obtain excellent electrical insulation, low dielectric properties, high rigidity, high toughness, low water absorption, high heat resistance, chemical resistance, etc.
According to the fourth aspect of the present invention , it is possible to prevent deterioration of the insulation of the stator and rotor of a rotating electric machine, and to effectively prevent failures such as a sudden stop of the rotating electric machine.

1 is a cross-sectional view illustrating an embodiment of an insulating material for a rotating electric machine and a rotating electric machine according to the present invention; 1 is a perspective explanatory view showing a stator core and slots, and an insulating material in an embodiment of an insulating material for a rotating electric machine according to the present invention and a rotating electric machine according to the present invention; 1 is a perspective explanatory view showing a schematic view of a core and slots of a stator in an embodiment of a rotating electric machine according to the present invention; 1 is an explanatory diagram illustrating a polyarylene ether ketone resin sheet according to an embodiment of an insulating material for a rotating electric machine according to the present invention; 1 is an overall explanatory diagram illustrating a schematic view of a polyarylene ether ketone resin sheet manufacturing apparatus in an embodiment of a manufacturing method for an insulating material for a rotating electric machine according to the present invention; FIG. 4 is a cross-sectional explanatory view showing a schematic diagram of a second embodiment of an insulating material for a rotating electric machine and a rotating electric machine according to the present invention.

A preferred embodiment of the present invention will now be described with reference to the drawings. In this embodiment, the insulating material for a rotating electric machine is an insulating material in which a plurality of slots 5 are recessed into the stator 3 of a rotating electric machine 1 and an insulating material 10 for a conductive winding 7 is inserted into each slot 5, as shown in Figures 1 to 5. The insulating material 10 is a thermoplastic polyarylene ether ketone resin sheet 11, and this polyarylene ether ketone resin sheet 11 is used as a wall member 14 interposed between the slot 5 and the plurality of conductive windings 7.

As partially shown in Figures 1 to 3, a rotating electric machine 1 is composed of a motor 2 for an electric vehicle or a hybrid vehicle, and a stator 3 that surrounds and rotates a rotor is installed on the inner periphery of a housing. The stator 3 has a cylindrical core 4 that is fitted to a rotatable rotor, and a plurality of conductive windings 7 that are housed in the core 4. A plurality of slots 5 are formed in a line in the circumferential direction of the inner periphery of the core 4 that faces the rotor, and a plurality of conductive windings 7 that generate a magnetic field are wound in each of the slots 5 and indirectly housed therein.

As shown in Figures 1 to 3, the core 4 of the stator 3 is formed by laminating iron cores made of multiple silicon steel sheets or the like, or is integrally molded, in order to reduce the effects of eddy currents. Each slot 5 is recessed to form an approximately U-shape, with its opening 6 directed toward the center of the core 4 and its bottom formed as a flat or curved surface. The opening 6 of this slot 5 is formed narrower than the bottom as necessary to prevent the polyarylene ether ketone resin sheet 11, which is the insulating material 10, from popping out or falling off. Each conductive winding 7 is mainly made of distributed-wound round copper wire, but if it is desired to improve the winding density, a rectangular copper wire with a rectangular (square) cross section is used.

As shown in Figures 1, 2, and 4, the polyarylene ether ketone resin sheet 11, which is the insulating material 10, is bent into a flexible, approximately U-shaped planar shape and is detachably inserted into the slot 5 with its opening 12 facing the center of the core 4 to directly accommodate the multiple conductive windings 7. The polyarylene ether ketone resin sheet 11 is used as the insulating material 10 because the use of the polyarylene ether ketone resin sheet 11 can improve electrical properties, mechanical properties, heat resistance, chemical resistance, radiation resistance, hydrolysis resistance, low water absorption, recyclability, etc. The upper and lower end portions 13 of the polyarylene ether ketone resin sheet 11 in Figure 2 are folded back outward and engage with the peripheral portions of the slot 5 on the front and back sides of the core 4 to prevent misalignment and falling off.

Such a polyarylene ether ketone resin sheet 11 is inserted into the slot 5 of the core 4 and positioned to house multiple conductive windings 7. This housing allows the sheet to be interposed as a wall member 14 between the inner surface of the slot 5 and the multiple conductive windings 7, separating the slot 5 from the multiple conductive windings 7 and functioning to ensure insulation between them.

Specific examples of the polyarylene ether ketone resin sheet 11 include a polyether ketone (PEK) resin sheet, a polyether ether ketone (PEEK) resin sheet, a polyether ketone ketone (PEKK) resin sheet, a polyether ether ketone ketone (PEEKK) resin sheet, and a polyether ketone ether ketone ketone (PEKEKK) resin sheet. Although any of these resin sheets can be used as the insulating material 10, a polyether ether ketone resin sheet is optimal from the standpoints of availability, ease of molding, manufacturing costs, and the like.

In order to realize high current and high voltage in the rotating electric machine 1, the electrical properties (electrical insulation) of the polyarylene ether ketone resin sheet 11 are preferably such that the dielectric breakdown voltage in the silicone oil is 7 kV or more, the dielectric breakdown strength, which is the dielectric breakdown voltage per unit thickness of the silicone oil, is 40 kV/mm or more, the relative dielectric constant at a frequency of 1 GHz is 3.1 or less, and the dielectric tangent is 0.01 or less.

The mechanical properties of the polyarylene ether ketone resin sheet 11 are preferably a tensile modulus of 3000 N/mm2 or more, a maximum tensile strength of 80 N/ ^{mm2 or} more, and a tensile elongation at break of 80% or more in order to improve rigidity and toughness. The water absorption rate at 23°C is preferably 1.0% or less in order to maintain excellent electrical properties even in a high humidity environment. Furthermore, the thickness is preferably 50 μm or more and 1000 μm or less in order to increase the occupancy rate of the conductive winding 7 while preventing a decrease in the electrical insulation of the polyarylene ether ketone resin sheet 11.

The relative crystallinity of the polyarylene ether ketone resin sheet 11 is 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 100%. This is because if the relative crystallinity of the polyarylene ether ketone resin sheet 11 is less than 80%, the heat resistance is insufficient, and the heat generated by the motor 2 may cause the wall member 14 to deform, crack, or change in dimension. In addition, the tensile modulus of the polyarylene ether ketone resin sheet 11 is low and the rigidity is insufficient, so there is a risk of buckling when the wall member 14 is inserted into the slot 5 of the core 4.

The crystallization of the polyarylene ether ketone resin sheet 11 can be expressed by the relative crystallinity. The relative crystallinity of the polyarylene ether ketone resin sheet 11 is calculated by the following formula based on the results of thermal analysis measured at a heating rate of 10° C./min using a differential scanning calorimeter.
Relative crystallinity (%)={1-(ΔHc/ΔHm)}×100
ΔHc: Heat of recrystallization peak (J / g)
ΔHm: Heat of crystal melting peak (J / g)

From the viewpoint of maintaining heat resistance, the glass transition point of the polyarylene ether ketone resin sheet 11 is 140°C or higher, preferably 145°C or higher, more preferably 150°C or higher, and even more preferably 155°C or higher. The upper limit of the glass transition point of the polyarylene ether ketone resin sheet 11 is not particularly limited, but in practice it is 180°C or lower. This is because if the glass transition point temperature exceeds 180°C, when the polyarylene ether ketone resin sheet 11 is extruded, the extrusion molding temperature exceeds 450°C, requiring special equipment for the extrusion molding equipment, which leads to high costs. In addition, the extruder that can be used is limited.

The glass transition point of the polyarylene ether ketone resin sheet 11 is the peak temperature of the loss modulus (E'') curve in the temperature change of the dynamic viscoelasticity measurement. The peak temperature of the loss modulus (E'') of the polyarylene ether ketone resin sheet 11 is in the above range in the extrusion direction and the width direction (perpendicular to the extrusion direction).

Now, the polyarylene ether ketone resin, which is the molding material M of the polyarylene ether ketone resin sheet 11, is a crystalline resin consisting of an arylene group, an ether group, and a carbonyl group, and examples of such resins include those described in Japanese Patent Publication No. 5709878 and Japanese Patent Publication No. 5847522. Specific examples of this polyarylene ether ketone resin include, for example, a polyether ether ketone (PEEK) resin having a chemical structure represented by chemical formula (1), a polyether ketone (PEK) resin having a chemical structure represented by chemical formula (2), a polyether ketone ketone (PEKK) resin having a chemical structure represented by chemical formula (3), a polyether ether ketone ketone (PEEKK) resin having a chemical structure represented by chemical formula (4), or a polyether ketone ether ketone ketone (PEKEKK) resin having a chemical structure represented by chemical formula (5).

The polyarylene ether ketone resin may be used alone or in a mixture of two or more types. The polyarylene ether ketone resin may also be a copolymer having two or more chemical structures represented by chemical formulas (1) to (5). The polyarylene ether ketone resin is usually used in a form suitable for molding, such as a powder, granule, or pellet form. Among these polyarylene ether ketone resins, polyether ether ketone resin and polyether ketone ketone resin are preferred in terms of moldability of the resin sheet. More preferably, polyether ether ketone resin is optimal in terms of ease of availability and cost.

Specific examples of polyether ether ketone resins include the Victrex Powder series, the Victrex Granules series (product name manufactured by Victrex), the VestaKeep series (product name manufactured by Daicel-Evonik), and the KetaSpire PEEK series (product name manufactured by Solvay Specialty Polymers). Specific examples of polyether ketone ketone resins include the KEPSTAN series (product name manufactured by Arkema).

The molding material M contains at least a polyarylene ether ketone resin, but in addition to this polyarylene ether ketone resin, polyimide resins such as polyimide (PI) resin, polyamideimide (PAI) resin, and polyetherimide (PEI) resin, polyamide 4T (PA4T) resin, polyamide 6T (PA6T) resin, modified polyamide 6T (modified PA6T) resin, polyamide 9T (PA9T) resin, polyamide 10T (PA10T) resin, polyamide 11T (PA11T) resin, polyamide 6 (PA6) resin, polyamide 66 (PA66) resin, and polyamide 46 (PA46) resin, polyamide resins such as polysulfone (PSU) resin, polyethersulfone (PES) resin, and polyphenylene sulfone (PPSU) resin, polyphenylene sulfide (PPS) resin, polyphenylene sulfide ketone resin, and polyphenylene sulfide ketone resin may also be used, provided that the characteristics of the present invention are not impaired. Polyarylene sulfide resins such as polyphenylene sulfide ketone sulfone resin, polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polyethylene naphthalate (PEN) resin and other polyester resins, polytetrafluoroethylene (PTFE) resin, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin, tetrafluoroethylene-hexafluoropropyl copolymer (FEP) resin, tetrafluoroethylene-ethylene copolymer (ETFE) resin, polychlorotrifluoroethylene (PCTFE) resin, polyvinylidene fluoride (PVdF) resin, fluorine resins such as vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resin, polycarbonate (PC) resin, polyarylate (PAR) resin, liquid crystal polymer (LCP), etc. are added as necessary.

In addition to the above resins, antioxidants, light stabilizers, ultraviolet absorbers, plasticizers, lubricants, flame retardants, antistatic agents, heat resistance enhancers, inorganic compounds, organic compounds, etc. may be selectively added to the molding material M within the limits that do not impair the characteristics of the present invention.

By using the polyarylene ether ketone resin of the molding material M, the polyarylene ether ketone resin sheet 11 is manufactured into a resin sheet having a thickness of 50 μm or more and 1000 μm or less. The polyarylene ether ketone resin sheet 11 can be manufactured by known manufacturing methods such as melt extrusion molding, calendar molding, or casting, but from the viewpoint of handling and simplification of equipment, it is preferable to continuously extrude the sheet by melt extrusion molding.

Here, the melt extrusion molding method is a method of melt-kneading a molding material M using a melt extruder 20 of a manufacturing apparatus as shown in Figure 5, and continuously extruding a polyarylene ether ketone resin sheet 11 from a T-die 23 of the melt extruder 20 to manufacture the polyarylene ether ketone resin sheet 11.

The manufacturing apparatus for the polyarylene ether ketone resin sheet 11 is not particularly limited, but is an apparatus for manufacturing the polyarylene ether ketone resin sheet 11 using a molding material M containing polyarylene ether ketone resin, and is configured to include a melt extrusion molding machine 20 that melts and kneads the molding material M, a T-shaped die 23 that is attached to the melt extrusion molding machine 20 and extrudes the polyarylene ether ketone resin sheet 11, a cooling roll 26 that cools the polyarylene ether ketone resin sheet 11 extruded from the T-shaped die 23, a pair of pressure rolls 27 that contact the polyarylene ether ketone resin sheet 11 extruded from the T-shaped die 23 and press them against the cooling roll 26, and a winder 28 that winds up the polyarylene ether ketone resin sheet 11 cooled by the cooling roll 26.

The melt extrusion molding machine 20 is, for example, a single-screw extrusion molding machine or a twin-screw extrusion molding machine, and functions to melt and knead the input molding material M. A raw material inlet 21 for the molding material M is installed at the upper rear of the melt extrusion molding machine 20, and an inert gas supply pipe 22 is connected to this raw material inlet 21, which supplies an inert gas such as helium gas, neon gas, argon gas, krypton gas, nitrogen gas, carbon dioxide gas, etc. (see arrow in Figure 5) as needed. The inflow of the inert gas through this inert gas supply pipe 22 effectively prevents oxidative deterioration and oxygen cross-linking of the molding material M.

The temperature of the polyarylene ether ketone resin during melt kneading in the melt extrusion molding machine 20 is not particularly limited as long as it is a temperature at which the polyarylene ether ketone resin can be melted and does not decompose, but it is preferably in the range of not less than the melting point of the polyarylene ether ketone resin but not more than the thermal decomposition temperature of the polyarylene ether ketone resin.

Specifically, the range is preferably 320°C or higher and 450°C or lower, more preferably 360°C or higher and 420°C or lower, and even more preferably 380°C or higher and 400°C or lower. This is because if the temperature is lower than the melting point of the polyarylene ether ketone resin, the molding material M containing the polyarylene ether ketone resin cannot be melt extrusion molded, and conversely, if the temperature exceeds the thermal decomposition temperature, the polyarylene ether ketone resin may be violently decomposed.

The T-die 23 is attached to the tip of the melt extrusion molding machine 20 via a connecting pipe 24, and functions to mold the molten molding material M into a strip-shaped polyarylene ether ketone resin sheet 11 and continuously extrude it downward. A gear pump 25 attached to the connecting pipe 24 is located upstream of the T-die 23, and this gear pump 25 transfers the molding material M to the T-die 23 at a constant speed and with high precision. A filter (not shown) is selectively installed between the T-die 23 and the gear pump 25 for the purpose of separating gel or foreign matter from the molten molding material M.

The temperature during extrusion of the T-die 23 is adjusted to a range between the melting point of the polyarylene ether ketone resin and the thermal decomposition temperature of the polyarylene ether ketone resin, specifically, 320°C to 450°C, preferably 360°C to 420°C, and more preferably 380°C to 400°C. This is because if the temperature is below the melting point of the polyarylene ether ketone resin, it becomes difficult to melt extrude the molding material M containing the polyarylene ether ketone resin, and conversely, if the temperature exceeds the thermal decomposition temperature, the polyarylene ether ketone resin may decompose violently.

The cooling roll 26 is, for example, a metal roll with a larger diameter than the pair of pressure rolls 27, and is rotatably supported below the T-die 23 to clamp the extruded polyarylene ether ketone resin sheet 11 between itself and the pressure roll 27. Together with the pressure roll 27, the polyarylene ether ketone resin sheet 11 is cooled in a short period of time while controlling its thickness within a predetermined range.

The cooling roll 26, like the pair of pressure-bonding rolls 27, is adjusted to a temperature range of not less than the glass transition point of the polyarylene ether ketone resin sheet 11 + 20°C and not more than the melting point of the polyarylene ether ketone resin sheet 11, preferably not less than the glass transition point of the polyarylene ether ketone resin sheet 11 + 30°C and not more than the glass transition point of the polyarylene ether ketone resin sheet 11 + 150°C, more preferably not less than the glass transition point of the polyarylene ether ketone resin sheet 11 + 50°C and not more than the glass transition point of the polyarylene ether ketone resin sheet 11 + 100°C, and even more preferably not less than the glass transition point of the polyarylene ether ketone resin sheet 11 + 60°C and not more than the glass transition point of the polyarylene ether ketone resin sheet 11 + 90°C, and is in sliding contact with the polyarylene ether ketone resin sheet 11.

The temperature of the cooling roll 26 is adjusted to a temperature range of the glass transition point of the polyarylene ether ketone resin sheet 11 plus 20°C and less than the melting point of the polyarylene ether ketone resin sheet 11 so that the relative crystallinity of the polyarylene ether ketone resin sheet 11 is adjusted to 80% or more.

To explain this point, if the temperature of the cooling roll 26 is less than the glass transition point + 20°C of the polyarylene ether ketone resin sheet 11, the relative crystallinity of the polyarylene ether ketone resin sheet 11 will be less than 80%, and the heat generated by the motor 2 may cause the wall member 14 to deform, crack, or change in size. In addition, the tensile modulus of the polyarylene ether ketone resin sheet 11 is small and the rigidity is insufficient, so that when the wall member 14 is inserted into the slot 5 of the stator 3, it may buckle. On the other hand, if the temperature of the cooling roll 26 is equal to or higher than the melting point of the polyarylene ether ketone resin sheet 11, the polyarylene ether ketone resin sheet 11 may stick to the cooling roll 26 during the production of the polyarylene ether ketone resin sheet 11 and break.

The method for adjusting the temperature or cooling the cooling roll 26 is not particularly limited, but examples include methods using a heat medium such as air, water, or oil, or methods using an electric heater or dielectric heating.

A pair of pressure rolls 27 are rotatably supported below the T-die 23 so as to sandwich the cooling roll 26. Between the pair of pressure rolls 27 and the winding tube 29 of the winding machine 28 located downstream of the pair of pressure rolls 27, a slit blade 30 that forms a slit on the side of the polyarylene ether ketone resin sheet 11 is at least vertically movable and between the slit blade 30 and the winding machine 28, a required number of tension rolls 31 are rotatably supported to apply tension to the polyarylene ether ketone resin sheet 11 for smooth winding.

To improve the adhesion between the polyarylene ether ketone resin sheet 11 and the cooling roll 26, the peripheral surface of each pressure roll 27 is coated with a rubber layer such as at least natural rubber, isoprene rubber, butadiene rubber, norbornene rubber, acrylonitrile butadiene rubber, nitrile rubber, urethane rubber, silicone rubber, or fluororubber as necessary, and inorganic compounds such as silica or alumina are selectively added to this rubber layer. Of these, it is preferable to use silicone rubber or fluororubber, which have excellent heat resistance.

The pressure roller 27 may be a metal elastic roller with a metal surface, if necessary. When this metal elastic roller is used, it is possible to form a polyarylene ether ketone resin sheet 11 with a smooth surface. Specific examples of this metal elastic roller include a metal sleeve roller, an air roller (manufactured by Dymco: product name), and a UF roller (manufactured by Hitachi Zosen: product name).

Similar to the cooling roll 26, such a pair of pressure-bonding rolls 27 is adjusted to a temperature range of not less than the glass transition point of the polyarylene ether ketone resin sheet 11 + 20°C and not more than the melting point of the polyarylene ether ketone resin sheet 11, preferably not less than the glass transition point of the polyarylene ether ketone resin sheet 11 + 30°C and not more than the glass transition point of the polyarylene ether ketone resin sheet 11 + 150°C, more preferably not less than the glass transition point of the polyarylene ether ketone resin sheet 11 + 50°C and not more than the glass transition point of the polyarylene ether ketone resin sheet 11 + 100°C, and even more preferably not less than the glass transition point of the polyarylene ether ketone resin sheet 11 + 60°C and not more than the glass transition point of the polyarylene ether ketone resin sheet 11 + 90°C, and is pressed against the polyarylene ether ketone resin sheet 11.

The temperature of the pressure roller 27 is adjusted to the relevant temperature range in order to adjust the relative crystallization of the polyarylene ether ketone resin sheet 11 to 80% or more. That is, if the temperature of the pressure roller 27 is less than the [glass transition point + 20°C] of the polyarylene ether ketone resin sheet 11, the relative crystallization of the polyarylene ether ketone resin sheet 11 will be less than 80%, and the wall member 14 will be deformed, cracked, or its dimensions will change due to the heat generated by the motor 2. In addition, the rigidity of the polyarylene ether ketone resin sheet 11 will be insufficient, and there is a risk of buckling when inserted into the slot 5 of the core 4. On the other hand, if the temperature of the pressure roller 27 is equal to or higher than the melting point of the polyarylene ether ketone resin sheet 11, the polyarylene ether ketone resin sheet 11 will stick to the cooling roller 26 during the production of the polyarylene ether ketone resin sheet 11, and there is a risk of breakage.

As with the cooling roll 26, the temperature adjustment and cooling methods for the pressure roll 27 are not limited, and examples include methods using a heat medium such as air, water, oil, etc., or an electric heater or dielectric heating.

In the above configuration, when manufacturing a polyarylene ether ketone resin sheet 11 for a rotating electric machine 1, first, molding material M is charged into the raw material inlet 21 of the melt extrusion molding machine 20, and the molding material M is melt-kneaded, and the polyarylene ether ketone resin sheet 11 is continuously extruded into a strip shape from the T-die 23. At this time, the moisture content of the polyarylene ether ketone resin before melt-kneading is adjusted to 2000 ppm or less, preferably 1000 ppm or less, more preferably 500 ppm or less, and even more preferably 300 ppm or less.

This is because if the water content of the polyarylene ether ketone resin before melt-kneading exceeds 2000 ppm, the polyarylene ether ketone resin may foam. The lower limit of the water content of the polyarylene ether ketone resin before melt-kneading is not particularly limited, but is preferably 100 ppm or more.

Once the polyarylene ether ketone resin sheet 11 is extruded, it is wound sequentially around a cooling roll 26, a pair of pressure rolls 27, a tension roll 31, and the winding tube 29 of the winding machine 28. The polyarylene ether ketone resin sheet 11 is then rubbed against the cooling roll 26 to cool it for a short period of time. Both sides of the polyarylene ether ketone resin sheet 11 are then cut with a slit blade 30 to arrange the sheet into a neat shape, and the sheet is then wound sequentially around the winding tube 29 of the winding machine 28 to produce a polyarylene ether resin sheet for a rotating electric motor 1.

At this time, the relative crystallinity and storage modulus (E') of the polyarylene ether ketone resin sheet 11 can be adjusted by immediately cooling the polyarylene ether ketone resin sheet 11 extruded from the T-die 23. In addition, as a method for adhering the polyarylene ether ketone resin sheet 11 to the cooling roll 26, from the viewpoints of handling and simplification of equipment, it is preferable to adopt a touch roll method in which the polyarylene ether ketone resin sheet 11 is pressed against the cooling roll 26 by a pressure roll 27 to adhere to it.

The contact time between the polyarylene ether ketone resin sheet 11 and the cooling roll 26 is not particularly limited, but from the viewpoint of instantly cooling the polyarylene ether ketone resin sheet 11, it is optimal to set the contact time to 0.1 seconds or more and 120 seconds or less, preferably 0.5 seconds or more and 60 seconds or less, and more preferably 1 second or more and 30 seconds or less.

The surface of the polyarylene ether ketone resin sheet 11 may be left as it is, but fine irregularities can be formed to a degree that does not lose the effect of the present invention, thereby reducing the coefficient of friction of the surface. Examples of methods for forming the fine irregularities include (1) melt-kneading the polyarylene ether ketone resin with a melt extrusion molding machine 20, extruding the melt-kneaded polyarylene ether ketone resin from a T-die 23 onto a cooling roll 26 having fine irregularities on its circumferential surface, and sandwiching the polyarylene ether ketone resin sheet 11 between the T-die 23 and the cooling roll 26 to form fine irregularities, (2) spraying fine inorganic compounds such as zirconia, glass, and stainless steel, polycarbonate resin, polyamide resin, or organic compounds such as plant seeds onto the polyarylene ether ketone resin sheet 11 to form fine irregularities, and (3) press-molding the polyarylene ether ketone resin sheet 11 with a mold having fine irregularities to form fine irregularities.

Of these methods, method (1) is optimal from the standpoint of simplifying the equipment, the accuracy of the size of the unevenness, the uniformity of the unevenness formation, or the ease of forming the unevenness, and the continuous formation of the unevenness.

To explain the formation method of (1) in more detail, there are (1-1) a method in which polyarylene ether ketone resin is discharged from the T-die 23 of the melt extrusion molding machine 20 onto a cooling roll 26 having fine irregularities on its peripheral surface, and the discharged material is sandwiched between the cooling roll 26 and a pressure roll 27 having fine irregularities on its peripheral surface, and molded simultaneously with the melt extrusion molding of the polyarylene ether ketone resin sheet 11, and (1-2) a method in which the molded polyarylene ether ketone resin sheet 11 is sandwiched between a cooling roll 26 having fine irregularities on its peripheral surface and a pressure roll 27 having fine irregularities on its peripheral surface, and irregularities are formed. Among these, the formation method of (1-1) is the most suitable from the viewpoint of simplifying the equipment.

The dielectric breakdown voltage of the produced polyarylene ether ketone resin sheet in silicone oil is 7 kV or more, preferably 9 kV or more, and more preferably 10 kV or more. The dielectric breakdown strength, which is the dielectric breakdown voltage per unit thickness of the produced polyarylene ether ketone resin sheet 11 in silicone oil, is 40 kV/mm or more, preferably 50 kV/mm or more, and more preferably 60 kV/mm or more and 400 kV/mm or less. This is because if the dielectric breakdown strength per unit thickness of the polyarylene ether ketone resin sheet 11 in silicone oil is less than 40 kV/mm, there is a risk of dielectric breakdown due to surge voltage when the polyarylene ether ketone resin sheet 11 is used as the insulating material 10.

The relative dielectric constant of the polyarylene ether ketone resin sheet 11 at 23°C and a frequency of 1 GHz is 3.1 or less, preferably 3.05 or less, but in practice is 1.5 to 3.1. This is because if the relative dielectric constant of the polyarylene ether ketone resin sheet 11 at a frequency of 1 GHz exceeds 3.1, the partial discharge inception voltage, which is the initial phenomenon of dielectric breakdown, cannot be sufficiently increased, making it difficult to prevent dielectric breakdown due to surge voltage.

The dielectric tangent of the polyarylene ether ketone resin sheet 11 at 23°C and a frequency of 1 GHz is 0.01 or less, preferably 0.007 or less, more preferably 0.005 or less, and even more preferably 0.003 or less. This is because if the dielectric tangent at 1 GHz is 0.01 or less, it is possible to prevent the polyarylene ether ketone resin sheet 11 from melting or thermally decomposing due to self-heating. The lower limit of this dielectric tangent is not limited, but is practically 0.0001 or more.

The tensile modulus of the polyarylene ether ketone resin sheet 11 is 3000 N/mm ² or more, preferably 3300 N/mm ² or more and 5000 N/mm ² or less, more preferably 3500 N/mm ² or more and 4700 N/mm ² or less, and even more preferably 4000 N/mm ² or more and 4500 N/mm ² or less. This is because, when the tensile modulus of the polyarylene ether ketone resin sheet 11 is less than 3000 N/mm ² , the rigidity becomes insufficient, and there is a risk of buckling when the polyarylene ether ketone resin sheet 11 is processed into the wall member 14 and inserted into the slot 5. In addition, when the tensile modulus of the polyarylene ether ketone resin sheet 11 exceeds 5000 N/mm ² , it takes a long time to mold the polyarylene ether ketone resin sheet 11, and cost reduction cannot be expected.

The polyarylene ether ketone resin sheet 11 has a maximum tensile strength of 80 N/ ^mm2 or more, preferably 90 N/ ^mm2 or more, and more preferably 100 N/ ^mm2 or more. The tensile elongation at break is 80% or more, preferably 100% or more, and more preferably 200% or more. This is because, when the maximum tensile strength is less than 80 N/ ^mm2 and the elongation at break is less than 80%, the polyether ether ketone resin sheet does not have sufficient toughness, and therefore, when inserted into the slot 5 as the wall member 14, problems such as breakage, cracking, and tearing may occur.

The water absorption rate of the polyarylene ether ketone resin sheet 11 is 1.0% or less at a temperature of 23°C, but is preferably 0.7% or less, and more preferably 0.5% or less. This is because when the water absorption rate at 23°C is 1.0% or less, high electrical insulation can be maintained even in a high temperature and humidity environment. The lower the water absorption rate of this polyarylene ether ketone resin sheet 11 at 23°C, the more preferable it is, but in practical use, it is 0% or more.

The thickness of the polyarylene ether ketone resin sheet 11 varies depending on the size of the core 4 and the shape of the slot 5, but is preferably 50 μm to 1000 μm, preferably 100 μm to 750 μm, more preferably 125 μm to 500 μm, and even more preferably 150 μm to 300 μm. This is because if the thickness of the polyarylene ether ketone resin sheet 11 is less than 50 μm, sufficient electrical insulation cannot be obtained, and conversely, if the thickness of the polyarylene ether ketone resin sheet 11 exceeds 1000 μm, the occupancy rate of the conductive winding 7 in the slot 5 decreases, causing problems in miniaturizing the motor 2 and increasing its output.

According to the above configuration, the insulating material 10 is not a resin fiber sheet, but a polyarylene ether ketone resin sheet 11 with excellent electrical properties, and the thickness is set to 50 μm or more and 1000 μm or less, so that it can be made thinner and the occupancy rate of the conductive winding 7 can be increased. In addition, since the polyarylene ether ketone resin sheet 11 has a low water absorption rate, the electrical insulating properties such as the dielectric properties and dielectric strength are not easily affected by environmental changes such as temperature and humidity, and it is possible to effectively prevent frequency dependence from increasing.

In addition, the polyarylene ether ketone resin sheet 11 has excellent electrical insulation properties, which can suppress deterioration of electrical characteristics and effectively eliminate the risk of partial discharge occurring at low voltages. In addition, the polyarylene ether ketone resin sheet 11 has excellent heat resistance and chemical resistance, which can be used to insulate the motor 2 of electric vehicles, hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles, etc.

In addition, since the polyarylene ether ketone resin sheet 11 has excellent mechanical properties, even if it is inserted as the wall member 14 into the slot 5 of the core 4, it is expected that the wall member 14 will be largely prevented from breaking, cracking, splitting, etc. Furthermore, since the polyarylene ether ketone resin sheet 11 has excellent sliding properties, it can contribute to automating the work of inserting the wall member 14 into the slot 5 of the core 4, and in this case, it is expected that the work time can be greatly reduced compared to manual work.

Next, Figure 6 shows a second embodiment of the present invention, in which the insulating material 10 is a polyarylene ether ketone resin sheet 11 having a thickness of 50 μm or more and 1000 μm or less, and this polyarylene ether ketone resin sheet 11 is used as a wall member 14, as a partition member 15 that divides the inside of the wall member 14 into multiple sections, and as a covering member 16 that fits and covers the opening 12 of the wall member 14.

For example, when the motor 2 is a polyphase AC motor, the partition members 15 are formed into a dish-shaped cross section and attached to the inside of the wall member 14 in the required number, and function as interphase insulating paper to ensure insulation between each phase of the conductive winding 7. The covering member 16 is formed into a dish-shaped cross section, for example, and prevents the conductive winding 7 from protruding from inside the wall member 14 to the outside. The other parts are the same as those in the above embodiment, so their explanation will be omitted.

In this embodiment, the same effects as those of the above embodiment can be expected, and it is clear that it is possible to ensure insulation between each phase of a multi-phase coil and prevent the conductive winding 7 from protruding from within the wall member 14 while maintaining electrical insulation.

In the above embodiment, multiple slots 5 are recessed into the stator 3 of the rotating electric machine 1, but multiple slots 5 may be recessed into the rotor of the rotating electric machine 1, and a polyarylene ether ketone resin sheet 11 of the insulating material 10 may be inserted into each slot 5. In addition, in the above embodiment, the polyarylene ether ketone resin sheet 11 is simply shown, but this is not limited thereto, and for example, a resin fiber sheet may be laminated and bonded to one or both sides of the polyarylene ether ketone resin sheet 11.

In addition, when it is desired to obtain excellent oil impregnation and slipperiness, a pair of upper and lower resin fiber sheets can be provided in a multi-layer structure on both the front and back sides of the polyarylene ether ketone resin sheet 11. In this case, examples of the resin fiber sheets include resin sheets of crystalline thermoplastic resins with a melting point of 250°C or higher, amorphous thermoplastic resins with a glass transition point of 200°C or higher, or thermosetting resins.

Specific examples of crystalline thermoplastic resins having a melting point of 250°C are preferably polyimide (PI) resin, semi-aromatic polyamide resins such as polyamide 4T (PA4T) resin, polyamide 6T (PA6T) resin, modified polyamide 6T (modified PA6T) resin, polyamide 9T (PA9T) resin, and polyamide 10T (PA10T) resin, polyarylene sulfide resins such as polyphenylene sulfide (PPS) resin, polyphenylene sulfide ketone resin, polyphenylene sulfide sulfone resin, and polyphenylene sulfide ketone sulfone resin, polyether ketone (PEK) resin, and poly Examples of the non-crystalline thermoplastic resin having a glass transition temperature of 200° C. or higher include polyarylene ether ketone resins such as polyether ether ketone (PEEK) resin, polyether ketone ketone (PEKK) resin, polyether ether ketone ketone (PEEKK) resin, or polyether ketone ether ketone ketone (PEKEKK) resin, polyester resin, fluororesin such as polytetrafluoroethylene (PTFE) resin, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin, and tetrafluoroethylene-hexafluoropropyl copolymer (FEP) resin, liquid crystal polymer (LCP), etc. Specific examples of the non-crystalline thermoplastic resin having a glass transition temperature of 200° C. or higher include polyimide resins such as polyetherimide (PEI) resin, polysulfone resins such as polysulfone (PSU) resin, polyethersulfone (PES) resin, and polyphenylenesulfone (PPSU) resin, and polyarylate (PAR) resin, etc.

Specific examples of thermosetting resins include polyimide resins such as polyamideimide (PI) resins, epoxy resins, phenolic resins, silicone resins, and wholly aromatic aramid resins. Among these resins, crystalline thermoplastic resins or thermosetting resins are preferred from the viewpoint of chemical resistance. More preferably, polyarylene ether ketone resins are suitable for improving adhesion with polyarylene ether ketone resins, and even more preferably, polyether ether ketone resins are optimal in terms of ease of availability and cost.

EXAMPLES Hereinafter, examples of the insulating material for a rotating electrical machine according to the present invention will be described together with comparative examples.
Example 1
First, in order to manufacture an insulating material for a motor, a commercially available polyether ether ketone resin (manufactured by Solvay Specialty Polymers, product name: KetaSpire PEEK KT-851NL SP (hereinafter abbreviated as "KT-851NL SP")) was prepared as a polyarylene ether ketone resin, and this polyether ether ketone resin was dried for 12 hours or more in a dehumidified hot air dryer heated to 160°C.

After drying the polyether ether ketone resin, it was confirmed that the moisture content of the dried polyether ether ketone resin was 300 ppm or less. The polyether ether ketone resin was then set in a φ40 mm single-screw melt extruder equipped with a 900 mm wide T-die and melt-kneaded. This melt-kneaded polyether ether ketone resin was then continuously extruded from the T-die of the single-screw melt extruder to form a ribbon-shaped resin sheet made of polyether ether ketone resin, which is an insulating material.

The moisture content of the polyether ether ketone resin was measured by Karl Fischer titration using a trace moisture analyzer (manufactured by Mitsubishi Chemical Corporation, product name: CA-100 type). The single-screw melt extruder had an L/D ratio of 32, a compression ratio of 2.5, and a full-flight screw type screw.

The temperature of the single-screw melt extruder was adjusted to 380-400°C, the temperature of the T-die to 400°C, and the temperature of the connecting pipe connecting these single-screw melt extruders to the T-die to 400°C. The temperature of the molten polyether ether ketone resin was measured by measuring the resin temperature at the inlet of the T-die, which was found to be 397°C. When the polyether ether ketone resin was fed into the single-screw extruder, nitrogen gas was supplied at 18 L/min through an inert gas supply pipe.

After the polyether ether ketone resin sheet was extruded in this manner, both ends of the continuous polyether ether ketone resin sheet were cut with a slit blade and sequentially wound around a winding tube of a winding machine to produce a resin sheet 100 m long and 650 mm wide. At this time, the resin sheet was sequentially wound around a 210°C cooling roll with irregularities on the circumferential surface, a pair of pressure rolls made of silicone rubber, and a 6-inch winding tube located downstream of these, and was sandwiched between the cooling roll and the pressure roll. At this time, the surface temperature of the pressure roll was measured with a non-contact thermometer and was found to be 216°C.

Once the resin sheet, which is an insulating material for motors, was obtained, the sheet thickness, water absorption rate, relative crystallinity, mechanical properties, electrical properties, and long-term heat resistance of the resin sheet were measured, and the results are shown in Table 1. The mechanical properties were evaluated in terms of maximum tensile strength, tensile elongation at break, and tensile modulus. The electrical properties were evaluated in terms of breakdown voltage, breakdown strength, relative dielectric constant, and dielectric tangent. The breakdown voltage and breakdown strength were evaluated in silicone oil at temperatures of 23°C and 200°C.

The long-term heat resistance of the resin sheet was evaluated by placing the resin sheet in a hot air oven heated to 200°C and leaving it for 1000 hours, and measuring the mechanical and electrical properties before and after leaving it. The mechanical properties were evaluated in terms of maximum tensile strength, tensile elongation at break, and tensile modulus. The electrical properties were evaluated in terms of breakdown voltage, breakdown strength, dielectric constant, and dielectric dissipation factor.

The thickness of the resin sheet was measured using a micrometer (manufactured by Mitutoyo Corporation, product name: Coolant Proof Micrometer, code MDC-25PJ). The thickness was measured at 10 arbitrary points in the width direction (perpendicular to the extrusion direction) of the polyarylene ether ketone resin sheet, and the average value was taken as the sheet thickness.

Water Absorption of Resin Sheet The water absorption of the resin sheet was measured in accordance with JIS K 7209 Method A. The immersion time was 24 hours. The measurement was performed using three test pieces, and the average value of the measured values was taken as the water absorption.

Relative crystallinity of resin sheet The relative crystallinity of the resin sheet was measured by weighing about 8 mg of a measurement sample from the resin sheet and using a differential scanning calorimeter (manufactured by SII Nanotechnologies, Inc., product name: EXSTAR7000 series X-DSC7000) at a heating rate of 10° C./min and a measurement temperature range of 20° C. to 380° C. The crystallinity was calculated using the following formula from the heat quantity (J/g) of the crystal melting peak and the heat quantity (J/g) of the recrystallization peak obtained at this time.

Relative crystallinity (%)={1-(ΔHc/ΔHm)}×100
Here, ΔHc represents the heat quantity (J/g) of the recrystallization peak of the resin sheet when the temperature is increased at 10° C./min, and ΔHm represents the heat quantity (J/g) of the crystalline melting peak of the resin sheet when the temperature is increased at 10° C./min.

Mechanical properties of resin sheet The mechanical properties of the resin sheet were evaluated by the maximum tensile strength, tensile elongation at break, and tensile modulus at 23 ° C. The mechanical properties were measured in the extrusion direction and the width direction (perpendicular to the extrusion direction). The measurement was performed in accordance with JIS K 7127 under the conditions of a tensile speed of 50 mm/min, a temperature of 23 ° C. ± 2 ° C., and a relative humidity of 50 RH ± 5% RH. The maximum tensile strength, tensile elongation at break, and tensile modulus were measured five times, and the average values were taken as the maximum tensile strength, tensile elongation at break, and tensile modulus.

The dielectric breakdown voltage and dielectric breakdown strength of the resin sheet The dielectric breakdown voltage and dielectric breakdown strength of the resin sheet in silicone oil at temperatures of 23°C and 200°C were measured in accordance with IEC 60243-1. Specifically, the dielectric breakdown voltage and dielectric breakdown strength were measured in silicone oil by a temperature rise method (short-time method), with alternating current (50 Hz), temperatures of 23°C±2°C and 200°C, and the electrode shape was a cylinder with an upper electrode of φ25 mm and height of 25 mm, and a lower electrode serving as a base of φ25 mm and height of 25 mm. The dielectric breakdown voltage was measured five times, and the average value was taken as the dielectric breakdown voltage. The voltage rise rate is shown in Table 2.

The dielectric breakdown strength was calculated by measuring the sheet thickness at the location where the dielectric breakdown voltage was to be measured before measuring the dielectric breakdown voltage, and then dividing the dielectric breakdown voltage by the sheet thickness after measuring the dielectric breakdown voltage.

The dielectric constant and dielectric loss tangent of the resin sheet The dielectric constant and dielectric loss tangent of the resin sheet at a frequency of 1 GHz and a temperature of 23°C were measured by a cavity resonator perturbation method with reference to ASTM D2520. The network analyzer used was a PNA-L network analyzer N5230A (product name, manufactured by Agilent Technologies), and the cavity resonator used was a cavity resonator for 1 GHz; CP431 (product name, manufactured by Kanto Electronics Application Development). The dielectric constant and dielectric loss tangent were measured in an environment with a temperature of 23°C ± 1°C and a humidity of 50% RH ± 5% RH. The dielectric constant and dielectric loss tangent were measured twice, and the average values were taken as the dielectric constant and dielectric loss tangent.

- Long-term heat resistance (mechanical properties) of resin sheets
The mechanical properties of the resin sheet in the long-term heat resistance were evaluated by placing the resin sheet in a hot air oven at a temperature of 200° C. and leaving it for 1000 hours, evaluating the mechanical properties before and after leaving it, and judging the long-term heat resistance according to the following criteria. The mechanical properties were evaluated by the maximum tensile strength, tensile elongation at break, and tensile modulus. The mechanical properties were measured in the extrusion direction and the width direction (perpendicular to the extrusion direction). The measurement was performed in accordance with JIS K 7127 under the conditions of a tensile speed of 50 mm/min, a temperature of 23° C.±2° C., and a relative humidity of 50% RH±5% RH. The maximum tensile strength, tensile elongation at break, and tensile modulus were measured five times, and the average values were taken as the maximum tensile strength, tensile elongation at break, and tensile modulus.

Long-term heat resistance of mechanical properties = |(X1-X0)/X0 x 100|
X1: Measured value after standing still X0: Measured value before standing still [criteria]
◎: The rate of change is 10% or less. ○: The rate of change is between 10% and 20%.

- Long-term heat resistance (electrical properties) of resin sheets
The dielectric breakdown voltage and dielectric breakdown strength in the long-term heat resistance of the resin sheet were measured by placing the resin sheet in a hot air oven at a temperature of 200° C. and leaving it for 1000 hours, evaluating the dielectric breakdown voltage and dielectric breakdown strength before and after leaving it, and judging the long-term heat resistance according to the following criteria. The dielectric breakdown voltage and dielectric breakdown strength of the resin sheet in silicone oil at a temperature of 23° C. were measured in accordance with IEC 60243-1. Specifically, the measurements were performed in silicone oil using a temperature rise method (short-time method), with AC (50 Hz), a temperature of 23° C.±2° C., and an upper electrode cylindrical with a diameter of 25 mm and a height of 25 mm, and a lower electrode serving as a base cylindrical with a diameter of 25 mm and a height of 25 mm.

The dielectric breakdown voltage was measured five times, and the average value was used as the dielectric breakdown voltage. The voltage rise rate is shown in Table 2. In addition, the dielectric breakdown strength was calculated by measuring the sheet thickness at the point where the dielectric breakdown voltage was to be measured before measuring the dielectric breakdown voltage, and then dividing the dielectric breakdown voltage by the sheet thickness after measuring the dielectric breakdown voltage.

Dielectric breakdown strength and rate of change in dielectric breakdown strength = |(X1-X0)/X0 x 100|
X1: Measured value after standing still X0: Measured value before standing still [criteria]
◎: The rate of change is 10% or less. ○: The rate of change is between 10% and 20%.

- Long-term heat resistance of resin sheets (relative dielectric constant and dielectric tangent)
The dielectric constant and dielectric loss tangent in the long-term heat resistance of the resin sheet were evaluated by placing the resin sheet in a hot air oven at a temperature of 200°C and leaving it for 1000 hours, evaluating the dielectric constant and dielectric loss tangent before and after leaving it, and judging the long-term heat resistance according to the following criteria. The dielectric constant and dielectric loss tangent of the resin sheet at a frequency of 1 GHz and a temperature of 23°C were measured by a cavity resonator perturbation method with reference to ASTM D2520. The network analyzer used was a PNA-L network analyzer N5230A [product name, manufactured by Agilent Technologies], and the cavity resonator used was a cavity resonator for 1 GHz; CP431 [product name, manufactured by Kanto Electronics Application Development Co., Ltd.].

The measurements of the dielectric constant and the dielectric loss tangent were carried out in an environment of temperature: 23°C ± 1°C and humidity: 50% RH ± 5% RH. The dielectric constant and the dielectric loss tangent were measured five times, and the average values were used as the dielectric constant and the dielectric loss tangent.

Rate of change of dielectric constant and dielectric tangent = |(X1-X0)/X0 x 100|
X1: Measured value after standing still X0: Measured value before standing still [criteria]
◎: The rate of change is 10% or less. ○: The rate of change is between 10% and 20%.

Example 2
In order to manufacture an insulating material for a motor, the commercially available polyether ether ketone resin used in Example 1 was prepared as the polyarylene ether ketone resin, and a resin sheet made of polyether ether ketone resin was formed into a strip shape by the same method as in Example 1. After the resin sheet was formed into a strip shape, the sheet thickness, water absorption rate, relative crystallinity, mechanical properties, and electrical properties of the resin sheet were measured, and the measurement results are shown in Table 1. The temperature of the molten polyether ether ketone resin was measured by measuring the resin temperature at the inlet of the T-die, and was found to be 397°C. In addition, the surface temperature of the pressure roll was measured with a non-contact thermometer and found to be 213°C.

Example 3
As the polyarylene ether ketone resin, the commercially available polyether ether ketone resin used in Example 1 was prepared, and a resin sheet made of the polyether ether ketone resin was formed into a strip shape by the same method as in Example 1. After the resin sheet was formed into a strip shape, the sheet thickness, water absorption rate, relative crystallinity, mechanical properties, and electrical properties of the extrusion-molded resin sheet were measured, and the measurement results are shown in Table 1.

The temperature of the molten polyether ether ketone resin was measured at the entrance of the T-die, and was found to be 398°C. The cooling roll was also changed to 230°C. The temperature of the pressure roll was measured with a non-contact thermometer and was found to be 235°C.

Comparative Example 1
A commercially available wholly aromatic polyaramid fiber sheet (manufactured by DuPont Teijin Advanced Paper, product name: Nomex paper type 410, nominal thickness: 0.13 mm) was prepared as a wholly aromatic polyaramid fiber sheet for use as an insulating material for motors, and the sheet thickness, water absorption rate, mechanical properties, electrical insulation properties, and long-term heat resistance of this wholly aromatic polyaramid fiber sheet were measured in the same manner as in Example 1, and the measurement results are shown in Table 3. The longitudinal direction of the wholly aromatic polyaramid fiber sheet was the extrusion direction, and the transverse direction was the width direction (direction perpendicular to the extrusion direction).

In addition, when the wholly aromatic polyamide resin sheet was measured using a differential scanning calorimeter at a heating rate of 10°C/min over a measurement temperature range of 20°C to 380°C, no crystalline melting peak was observed, so the relative crystallinity was not calculated.

Comparative Example 2
A commercially available wholly aromatic polyaramid fiber sheet (manufactured by DuPont Teijin Advanced Paper, product name: Nomex paper type 410, nominal thickness: 0.25 mm) was prepared as a wholly aromatic polyaramid fiber sheet for insulating material, and the sheet thickness, water absorption rate, mechanical properties, electrical insulation properties, and long-term heat resistance of this wholly aromatic polyaramid fiber sheet were measured in the same manner as in Example 1, and the measurement results are shown in Table 3. The longitudinal direction of the wholly aromatic polyaramid fiber sheet was the extrusion direction, and the transverse direction was the width direction (direction perpendicular to the extrusion direction).

In addition, when the wholly aromatic polyamide resin sheet was measured using a differential scanning calorimeter at a heating rate of 10°C/min over a measurement temperature range of 20°C to 380°C, no crystalline melting peak was observed, so the relative crystallinity was not calculated.

[Results]
The mechanical properties of the resin sheet, which is the insulating material in each embodiment, are such that the tensile modulus is 3500 N/ ^mm2 or more, and the resin sheet is highly rigid, so that if the resin sheet is processed into a wall member, a partition member, or a covering member and inserted into the slot of a stator core, buckling can be prevented. In addition, the resin sheet in each embodiment has extremely high toughness, with a maximum tensile strength of 100 N/ ^mm2 or more and a tensile elongation at break of 200% or more, so that if the resin sheet is processed into a wall member, a partition member, or a covering member and inserted into the slot of a stator core, problems such as breakage, cracking, and tearing can be prevented in advance.

The water absorption rate of the resin sheet, which is the insulating material in each embodiment, was 1.0% or less, specifically 0.7% or less, at a temperature of 23°C. Therefore, even if the motor is used in a high temperature and humidity environment, the electrical properties such as dielectric breakdown strength, dielectric breakdown strength, dielectric constant, and dielectric loss tangent can be maintained.

The electrical insulation properties of the resin sheets of each embodiment in silicone oil at 23°C and 200°C are: breakdown voltage of 9 kV or more, breakdown strength (breakdown voltage per unit thickness) of 50 kV/mm or more, and relative dielectric constant at 23°C of 3.0 or less, so they are presumed to have excellent performance in preventing breakdown due to surge voltage. In addition, since the dielectric tangent is 0.003 or less, it is expected that melting and thermal decomposition due to self-heating will be eliminated.

The long-term heat resistance of the resin sheets of each embodiment was such that the rate of change in mechanical properties was 20% or less and the rate of change in electrical insulation was 10% or less before and after being placed in a hot air oven at 200°C. Therefore, by using the resin sheets of the embodiments in motors, excellent long-term heat resistance can be expected.

In contrast, the mechanical properties of the wholly aromatic polyaramid fiber sheets of each Comparative Example were such that the tensile elongation at break was less than 80%, which was problematic in terms of toughness, and the tensile modulus in the width direction was less than 3500 N/ ^mm2 , which was insufficient in terms of rigidity. Therefore, when the wholly aromatic polyaramid fiber sheets are processed into wall members, partition members, or covering members and inserted into the slots of the stator core, it is presumed that there is a considerable risk of buckling. In addition, the water absorption rate of the wholly aromatic polyaramid fiber sheets of each Comparative Example was extremely high at 10% or more, so it is presumed that the electrical insulation may be significantly affected by the usage environment.

In addition, the electrical insulation of the fully aromatic polyaramid fiber sheets of each comparative example is 40 kV/mm or less in terms of dielectric breakdown strength, which is the dielectric breakdown voltage per unit thickness, so it is presumed that problems with dielectric breakdown due to surge voltage will occur. Furthermore, the fully aromatic polyaramid fiber sheets of each comparative example have a dielectric loss tangent of 0.019 or more, so there is a risk of melting or thermal decomposition due to self-heating.

The insulating material for rotating electric machines and the rotating electric machine of the present invention are used in the manufacturing fields of electricity, electronics, automobiles, railway vehicles, etc.

Reference Signs List 1 Rotating electric machine 2 Motor 3 Stator 4 Core 5 Slot 7 Conductive winding 10 Insulating material 11 Polyarylene ether ketone resin sheet 14 Wall member 15 Partition member 16 Covering member 20 Melt extrusion molding machine 23 T-die (die)
26 Cooling roll 27 Pressure roll 28 Winder M Molding material

Claims (4)

An insulating material for a rotating electric machine, which is made of a polyarylene ether ketone resin sheet that is melt-extruded to prevent a short circuit in a rotating electric machine ,
The polyarylene ether ketone resin sheet has a relative crystallinity of 95% or more and 100% or less , a thickness of 100 μm or more and 750 μm or less, and a glass transition point of 150° C. or more and 180° C. or less ,
The electrical properties of the polyarylene ether ketone resin sheet are a dielectric breakdown strength in silicone oil of 9 kV or more, a dielectric breakdown strength per unit thickness in silicone oil of 50 kV/mm or more and 400 kV/mm or less , a relative dielectric constant at a frequency of 1 GHz of 1.5 or more and 3.1 or less , and a dielectric dissipation factor of 0.0001 or more and 0.007 or less,
The mechanical properties of the polyarylene ether ketone resin sheet are a tensile modulus of 3500 N/mm2 ^or more and 4700 N/mm2 ^or less , a maximum tensile strength of 100 N/mm2 ^or more, and a tensile elongation at break of 200% or more ;
1. An insulating material for a rotating electrical machine, comprising a polyarylene ether ketone resin sheet, the polyarylene ether ketone resin sheet having a water absorption rate of 0.7% or less at 23°C. The insulating material for rotating electrical machines according to claim 1, wherein the polyarylene ether ketone resin sheet of the insulating material is a polyether ether ketone resin sheet. The insulating material for rotating electrical machines according to claim 1 or 2, in which a substantially U-shaped polyarylene ether ketone resin sheet that houses a conductive winding is inserted into a slot formed in at least one of the stator and rotor of a rotating electrical machine, and the polyarylene ether ketone resin sheet is used as an insulating wall member interposed between the slot and the conductive winding. A rotating electric machine comprising the insulating material for rotating electric machines according to claim 1, 2, or 3.

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