JP2022000504A - Coating composition for electromagnetic steel sheet, electromagnetic steel sheet, laminated core and rotating electrical machinery - Google Patents

Abstract

To provide a coating composition for an electromagnetic steel sheet capable of reducing application of stress strain caused by an adhesive component, even if a sheet thickness of the electromagnetic steel sheet is thin, and obtaining heat resistance capable of securing adhesive strength, even when a motor heats up; and to provide an electromagnetic steel sheet using the same, a laminated core and a rotating electrical machinery.SOLUTION: In a coating composition for an electromagnetic steel sheet, the electromagnetic steel sheet used for a laminated core is an electromagnetic steel sheet in which the surface of a base steel sheet 2 is coated with an insulation coating 3 formed by applying the coating composition for the electromagnetic steel sheet. The coating composition for the electromagnetic steel sheet contains a cross-linked hot-melt adhesive comprising a polyester urethane resin and aromatic amine having a melting point of 50°C or higher and 200°C or lower which is a hardener, and a room temperature solidified resin having a softening temperature of 100°C or higher and 200°C or lower, and the content of the room temperature solidified resin is 50 pts. mass or more and 300 pts. mass or less to 100 pts. mass of the cross-linked hot-melt adhesive.SELECTED DRAWING: Figure 5

Description

The present invention relates to a coating composition for an electromagnetic steel sheet, an electromagnetic steel sheet, a laminated core, and a rotary electric machine.

As a core (iron core) used in a rotary electric machine, a laminated core in which a plurality of electromagnetic steel sheets are joined to each other and laminated is known. Caulking and welding are known as methods for joining electrical steel sheets to each other. In joining methods such as caulking and welding, the core iron loss tends to deteriorate because the steel sheet is subjected to mechanical strain and thermal strain. Adhesion is known as a joining method other than caulking and welding. Adhesion does not give mechanical strain or thermal strain to the steel sheet, so it is superior in core iron loss compared to caulking and welding.

On the other hand, in the joining of electromagnetic steel sheets by adhesion, stress strain is applied to the steel sheets by curing the adhesive. In recent years, further improvement in motor efficiency has been required, and further reduction in core iron loss has been required. Thinning of electrical steel sheets is effective in reducing core iron loss, but the Young's modulus of the steel sheets decreases as the sheet thickness decreases. Therefore, it is required to further reduce the stress strain that causes iron loss deterioration.

Epoxy resin has little volume change, is excellent in heat resistance, oil resistance, and chemical resistance, and is excellent as an adhesive for adhering electromagnetic steel sheets to each other. However, since it is necessary to raise the temperature to a relatively high temperature in order to cure the epoxy resin, stress is applied to the steel sheet during bonding, and iron loss may deteriorate. As an adhesive that can be adhered at a lower temperature than an epoxy resin, for example, one using a urethane resin is known (for example, Patent Documents 1 to 6). Further, a polymer adhesive layer made of baked enamel such as polyvinyl butyral and polyamide is formed on the surface of the steel plate, and a binder layer made of polyvinyl alcohol, amine and the like is arranged between the polymer adhesive layers for adhering the steel plates to each other. Is also known (Patent Document 7). However, with these adhesives and binders, it is difficult to obtain sufficient heat resistance applicable to applications exposed to high temperatures during use, such as motors for electric vehicles.

Japanese Unexamined Patent Publication No. 2017-179233 Japanese Unexamined Patent Publication No. 2017-186542 Japanese Unexamined Patent Publication No. 6-182929 Japanese Unexamined Patent Publication No. 6-271834 Japanese Unexamined Patent Publication No. 7-268501 Japanese Patent Application Laid-Open No. 2002-293864 Japanese Patent No. 6548081

The present invention uses a coating composition for electrical steel sheets, which can reduce the application of stress strain due to adhesive components even if the thickness of the electrical steel sheets is thin, and can obtain heat resistance that can secure the adhesive strength even when the motor generates heat. It is an object of the present invention to provide an electromagnetic steel sheet, a laminated core, and a rotary electric machine.

The present invention has the following configurations.
[1] A crosslinked hot melt adhesive composed of a polyester urethane resin which is a reaction product of a polyester polyol and a polyisocyanate and a curing agent, and a room temperature solidified resin are contained, and the softening point of the room temperature solidified resin is 100 ° C. A coating composition for an electromagnetic steel plate having a temperature of 200 ° C. or lower and a content of the room temperature solidified resin of 50 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the crosslinked hot melt adhesive.
[2] The coating composition for electrical steel sheets according to [1], wherein the curing agent is an aromatic amine having a melting point of 50 ° C. or higher and 200 ° C. or lower.
[3] An electromagnetic steel sheet having an insulating film on the surface coated with the coating composition for electrical steel sheets according to [1] or [2].
[4] The electromagnetic steel sheet according to [3], which has a plate thickness of 0.50 mm or less.
[5] A laminated core in which a plurality of electrical steel sheets according to [3] or [4] are laminated and bonded to each other.
[6] A rotary electric machine provided with the laminated core according to [5].

According to the present invention, a coating composition for electrical steel sheets, which can reduce the application of stress strain due to adhesive components even if the thickness of the electrical steel sheets is thin, and can obtain heat resistance that can secure the adhesive strength even when the motor generates heat. The used electromagnetic steel sheets, laminated cores and rotary electric machines can be provided.

It is sectional drawing of the rotary electric machine provided with the laminated core which concerns on 1st Embodiment of this invention. It is a side view of the laminated core. FIG. 2 is a cross-sectional view taken along the line AA of FIG. It is a top view of the material which forms the laminated core. FIG. 4 is a cross-sectional view taken along the line BB of FIG. It is an enlarged view of the part C of FIG. It is a side view of the manufacturing apparatus used for manufacturing the laminated core.

Hereinafter, with reference to the drawings, a laminated core according to an embodiment of the present invention, a rotary electric machine provided with the laminated core, and a material forming the laminated core will be described. In this embodiment, an electric motor as a rotary electric machine, specifically an AC electric motor, more specifically a synchronous electric motor, and more specifically, a permanent magnet field type electric motor will be described as an example. This type of motor is suitably adopted for, for example, an electric vehicle.

(Rotating machine 10)
As shown in FIG. 1, the rotary electric machine 10 includes a stator 20, a rotor 30, a case 50, and a rotary shaft 60. The stator 20 and the rotor 30 are housed in the case 50. The stator 20 is fixed in the case 50.
In the present embodiment, the rotary electric machine 10 adopts an inner rotor type in which the rotor 30 is located inside the stator 20 in the radial direction. However, as the rotary electric machine 10, an outer rotor type in which the rotor 30 is located outside the stator 20 may be adopted. Further, in the present embodiment, the rotary electric machine 10 is a 12-pole 18-slot three-phase AC motor. However, the number of poles, the number of slots, the number of phases, and the like can be changed as appropriate.
The rotary electric machine 10 can rotate at a rotation speed of 1000 rpm, for example, by applying an exciting current having an effective value of 10 A and a frequency of 100 Hz to each phase.

The stator 20 includes an adhesive laminated core for a stator (hereinafter referred to as a stator core) 21 and a winding not shown.
The stator core 21 includes an annular core back portion 22 and a plurality of teeth portions 23. In the following, the central axis O direction of the stator core 21 (or core back portion 22) is referred to as an axial direction, and the radial direction of the stator core 21 (or core back portion 22) (direction orthogonal to the central axis O) is referred to as a radial direction. The circumferential direction (direction that orbits around the central axis O) of the stator core 21 (or core back portion 22) is referred to as a circumferential direction.

The core back portion 22 is formed in an annular shape in a plan view of the stator 20 when viewed from the axial direction.
The plurality of tooth portions 23 project radially inward from the inner circumference of the core back portion 22 (toward the central axis O of the core back portion 22 along the radial direction). The plurality of tooth portions 23 are arranged at equal angular intervals in the circumferential direction. In the present embodiment, 18 tooth portions 23 are provided at every 20 degrees of the central angle centered on the central axis O. The plurality of tooth portions 23 are formed to have the same shape and the same size as each other. Therefore, the plurality of tooth portions 23 have the same thickness dimension as each other.
The winding is wound around the teeth portion 23. The winding may be a centralized winding or a distributed winding.

The rotor 30 is arranged radially inside the stator 20 (stator core 21). The rotor 30 includes a rotor core 31 and a plurality of permanent magnets 32.
The rotor core 31 is formed in an annular shape (annular ring) arranged coaxially with the stator 20. The rotating shaft 60 is arranged in the rotor core 31. The rotating shaft 60 is fixed to the rotor core 31.
The plurality of permanent magnets 32 are fixed to the rotor core 31. In this embodiment, a set of two permanent magnets 32 form one magnetic pole. The plurality of sets of permanent magnets 32 are arranged at equal angular intervals in the circumferential direction. In this embodiment, 12 sets (24 in total) of permanent magnets 32 are provided at every 30 degrees of the central angle centered on the central axis O.

In this embodiment, an embedded magnet type motor is adopted as a permanent magnet field type motor. The rotor core 31 is formed with a plurality of through holes 33 that penetrate the rotor core 31 in the axial direction. The plurality of through holes 33 are provided corresponding to the arrangement of the plurality of permanent magnets 32. Each permanent magnet 32 is fixed to the rotor core 31 in a state of being arranged in the corresponding through hole 33. The fixing of each permanent magnet 32 to the rotor core 31 can be realized, for example, by adhering the outer surface of the permanent magnet 32 and the inner surface of the through hole 33 with an adhesive. As the permanent magnet field type motor, a surface magnet type motor may be adopted instead of the embedded magnet type.

Both the stator core 21 and the rotor core 31 are laminated cores. For example, as shown in FIG. 2, the stator core 21 is formed by laminating a plurality of electromagnetic steel sheets 40 in the laminating direction.
The product thickness (total length along the central axis O) of each of the stator core 21 and the rotor core 31 is, for example, 50.0 mm. The outer diameter of the stator core 21 is, for example, 250.0 mm. The inner diameter of the stator core 21 is, for example, 165.0 mm. The outer diameter of the rotor core 31 is, for example, 163.0 mm. The inner diameter of the rotor core 31 is, for example, 30.0 mm. However, these values are examples, and the product thickness, outer diameter and inner diameter of the stator core 21, and the product thickness, outer diameter and inner diameter of the rotor core 31 are not limited to these values. Here, the inner diameter of the stator core 21 is based on the tip end portion of the teeth portion 23 in the stator core 21. That is, the inner diameter of the stator core 21 is the diameter of a virtual circle inscribed in the tips of all the teeth portions 23.

Each of the electromagnetic steel sheets 40 forming the stator core 21 and the rotor core 31 is formed, for example, by punching the material 1 as shown in FIGS. 4 to 6. Material 1 is a steel sheet (electrical steel sheet) that is a base material of the electromagnetic steel sheet 40. Examples of the material 1 include strip-shaped steel plates and cut plates.
Although the explanation of the laminated core is in the middle, the material 1 will be described below. In the present specification, the strip-shaped steel sheet that is the base material of the electromagnetic steel sheet 40 may be referred to as material 1. A steel sheet having a shape used for a laminated core by punching the material 1 may be referred to as an electromagnetic steel sheet 40.

(Material 1)
The material 1 is handled, for example, in a state of being wound around the coil 1A shown in FIG. 7. In this embodiment, non-oriented electrical steel sheets are used as the material 1. As the non-oriented electrical steel sheet, JIS C 2552: 2014 non-oriented electrical steel strip can be adopted. However, as the material 1, a grain-oriented electrical steel sheet may be used instead of the non-oriented electrical steel sheet. As the grain-oriented electrical steel sheet in this case, JIS C 2553: 2019 grain-oriented electrical steel strip can be adopted. Further, a non-oriented thin electromagnetic steel strip or a directional thin electromagnetic steel strip of JIS C 2558: 2015 can be adopted.

The upper and lower limit values of the average plate thickness t0 of the material 1 are set as follows, for example, in consideration of the case where the material 1 is used as the electromagnetic steel sheet 40.
As the material 1 becomes thinner, the manufacturing cost of the material 1 increases. Therefore, in consideration of the manufacturing cost, the lower limit of the average plate thickness t0 of the material 1 is 0.10 mm, preferably 0.15 mm, and more preferably 0.18 mm.
On the other hand, if the material 1 is too thick, the manufacturing cost becomes good, but when the material 1 is used as the electromagnetic steel sheet 40, the eddy current loss increases and the core iron loss deteriorates. In addition to this, since the insulating coating according to the present embodiment suppresses the generation of stress strain due to hardening, the adverse effect of the stress strain (increased iron loss) can be effectively suppressed particularly when the material 1 is thin. Therefore, considering the core iron loss and the manufacturing cost, the upper limit of the average plate thickness t0 of the material 1 is 0.65 mm, preferably 0.35 mm. Further, if the effect of suppressing stress strain is sufficiently obtained, the upper limit value is preferably 0.30 mm, more preferably 0.26 mm.
0.20 mm can be exemplified as a material that satisfies the above range of the average plate thickness t0 of the material 1.

The average plate thickness t0 of the material 1 includes not only the thickness of the base steel plate 2 described later but also the thickness of the insulating coating 3. Further, the method for measuring the average plate thickness t0 of the material 1 is, for example, the following measuring method. For example, when the material 1 is wound into the shape of the coil 1A, at least a part of the material 1 is unwound into a flat plate shape. In the material 1 unraveled into a flat plate shape, a predetermined position in the longitudinal direction of the material 1 (for example, a position 10% of the total length of the material 1 away from the longitudinal edge of the material 1) is selected. do. At this selected position, the material 1 is divided into five regions along the width direction thereof. The plate thickness of the material 1 is measured at four locations that are boundaries of these five regions. The average value of the plate thicknesses at the four locations can be set to the average plate thickness t0 of the material 1.

The upper and lower limit values of the average plate thickness t0 of the material 1 can be naturally adopted as the upper and lower limit values of the average plate thickness t0 of the electrical steel sheet 40. The method for measuring the average plate thickness t0 of the electrical steel sheet 40 is, for example, the following measuring method. For example, the thickness of the laminated core is measured at four locations (that is, every 90 degrees around the central axis O) at equal intervals in the circumferential direction. Each of the measured product thicknesses at the four locations is divided by the number of laminated electromagnetic steel sheets 40 to calculate the plate thickness per sheet. The average value of the plate thicknesses at the four locations can be set to the average plate thickness t0 of the electromagnetic steel sheet 40.

As shown in FIGS. 5 and 6, the material 1 includes a base steel plate 2 and an insulating coating 3. The material 1 is formed by covering both sides of a strip-shaped base steel plate 2 with an insulating coating 3. In the present embodiment, most of the material 1 is formed of the base steel plate 2, and the insulating film 3 thinner than the base steel plate 2 is laminated on the surface of the base steel plate 2.

The chemical composition of the base steel sheet 2 contains 2.5% to 4.5% Si in mass%, as shown below in units of mass%. By setting the chemical composition within this range, the yield strength of the material 1 (electrical steel sheet 40) can be set to, for example, 380 MPa or more and 540 MPa or less.

Si: 2.5% -4.5%
Al: 0.001% to 3.0%
Mn: 0.05% to 5.0%

When the material 1 is used as the electrical steel sheet 40, the insulating film 3 exhibits insulation performance between the electrical steel sheets 40 adjacent to each other in the stacking direction. Further, in the present embodiment, the insulating coating 3 has an adhesive ability and adheres the electromagnetic steel sheets 40 adjacent to each other in the laminating direction. The insulating coating 3 may have a single-layer structure or a multi-layer structure. More specifically, for example, the insulating coating 3 may have a single-layer structure having both insulating performance and adhesive ability, and may include a base insulating coating having excellent insulating performance and a ground insulating coating having excellent adhesive performance. It may have a multi-layer structure including.

In the present embodiment, the insulating coating 3 covers both sides of the base steel plate 2 without gaps over the entire surface. However, as long as the above-mentioned insulating performance and adhesive ability are ensured, a part of the layers of the insulating coating 3 may not cover both sides of the base steel plate 2 without gaps. In other words, a part of the layer of the insulating film 3 may be intermittently provided on the surface of the base steel sheet 2. However, in order to ensure the insulating performance, both sides of the base steel plate 2 need to be covered with the insulating film 3 so that the entire surface is not exposed. Specifically, when the insulating coating 3 does not have a base insulating coating having excellent insulating performance and has a single-layer structure having both insulating performance and adhesive ability, the insulating coating 3 has no gap over the entire surface of the base steel plate 2. Must be formed. On the other hand, when the insulating film 3 has a multi-layer structure including a base insulating film having excellent insulating performance and an upper insulating film having excellent adhesiveness, both the underlying insulating film and the upper insulating film are made of a base steel sheet. In addition to forming the base insulating film without gaps over the entire surface of No. 2, even if the underlying insulating film is formed without gaps over the entire surface of the base steel sheet and the upper ground insulating film is intermittently provided, both the insulating performance and the adhesive ability can be achieved.

The coating composition for forming the underlying insulating film is not particularly limited, and for example, a general treatment agent such as a chromic acid-containing treatment agent or a phosphate-containing treatment agent can be used.

The insulating film having adhesive ability is formed by applying a coating composition for an electromagnetic steel sheet described below on a base steel sheet. The insulating film made of the coating composition for electrical steel sheets is in an uncured or semi-cured state (B stage) before heat crimping at the time of manufacturing a laminated core, and the curing reaction proceeds by heating during heat crimping to adhere. Noh develops.

The coating composition for electrical steel sheets contains a crosslinked hot melt adhesive composed of a polyester-based urethane resin and a curing agent, and a room temperature solidified resin.

The polyester-based urethane resin is a reaction product (urethane resin) obtained by reacting a polyester polyol with a polyisocyanate. In general, urethane resin has viscoelastic properties that can be adjusted by the length of the carbon chain of the polyol, and a wide range of products from hard glass to rubber elastic regions are on the market.

Polyester polyols are superior in mechanical strength to polyether polyols. The polyester polyol is not particularly limited, and for example, a polyester-polyester type copolymer (a copolymer of butylene terephthalate and tetramethylene oxide glycol, etc.) and a polyester-polyester type copolymer (butylene terephthalate and butylene adipate) are used. Copolymer etc.) and the like. As the polyester polyol, one kind may be used alone, or two or more kinds may be used in combination.

The polyisocyanate is not particularly limited, and is, for example, tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenylenedi isocyanate, 1,4-phenylenedi isocyanate, xylyl. Range isocyanate, tetramethylxylylene diisocyanate, naphthylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, crude TDI, polymethylene polyphenylisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, hydride xylylene diisocyanate, isocyanurates thereof , Carbodiimide, burette and the like. As the polyisocyanate, one type may be used alone, or two or more types may be used in combination.

In order to heat-cure the insulating film during the production of the laminated core, the curing agent needs to have potential. Here, "the curing agent has potential" means that it has a property that the progress of the curing reaction is suppressed until the curing is started by heating. In this embodiment, an aromatic amine having a melting point (MP) of 50 ° C. or higher and 200 ° C. or lower is used as the curing agent having potential. When the MP of the aromatic amine is within the above range, both the potential and the appropriate bonding temperature range can be achieved, and the bonding strength between the electromagnetic steel sheets becomes high. The MP of the aromatic amine is preferably 60 ° C. or higher and 180 ° C. or lower.
The "melting point" is a value measured at a heating rate of 1 ° C./min by a visual method according to JIS K0064 (1992).

Specific examples of the aromatic amine include meta-phenylenediamine (MP: 62 ° C.), diaminodiethyldimethyldiphenylmethane (MP: 76 ° C.), diaminodiphenylmethane (MP: 89 ° C.), and dichlorodiaminodiphenylmethane (MP: 98 ° C.). , Trimethylenebis (4-aminobenzoate) (MP: 122-128 ° C.) and the like. As the aromatic amine, one kind may be used alone, or two or more kinds may be used in combination.

The content of the curing agent is preferably 3 parts by mass or more and 100 parts by mass or less, and more preferably 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polyester urethane resin. When the content of the curing agent is at least the lower limit of the above range, the adhesive strength between the electromagnetic steel sheets is high. When the content of the curing agent is not more than the upper limit of the above range, the pot life becomes long.

The room temperature solidified resin has a softening point of 100 ° C. or higher and 200 ° C. or lower, and can be solidified by cooling to room temperature (for example, 25 ° C.). The "softening point" refers to the melting point when the resin is a crystalline polymer and the glass transition temperature when the resin is an amorphous polymer, and conforms to JIS K6863 (1994) using a differential scanning calorimeter (DSC). It is a value measured at a heating rate of 5 ° C./min.

Specific examples of the room temperature solidified resin include rosin and rosin derivatives (hydrosin rosin, polymerized rosin, hydrogenated polymerized rosin, rosing lysellin ester, hydrogenated rosing lysellin ester, rosin pentaerythritol ester, hydrogenated rosin pentaerythritol ester, and the like. Disproportionate rosing lyserine ester, water-levelized rosin pentaerythritol ester, etc.), terpenephenol resin, hydrogenated terpenephenol resin, ketone resin, petroleum resin (aliphatic, aromatic, their copolymerization, alicyclic) Systems and their hydrogenated petroleum resins), terpene resins, hydrogenated terpene resins, kumaron-inden resins, phenolic resins, xylene resins and the like. As the room temperature solidified resin, one type may be used alone, or two or more types may be used in combination.

The softening point of the room temperature solidified resin is preferably 80 ° C. or higher and 230 ° C. or lower, and more preferably 100 ° C. or higher and 200 ° C. or lower. When the softening point of the room temperature solidified resin is at least the lower limit of the above range, the coating characteristics of the coating composition for electrical steel sheets are excellent, and heat resistance that can secure the adhesive strength even when the motor generates heat can be obtained. When the softening point of the room temperature solidified resin is not more than the upper limit of the above range, a laminated core having excellent magnetic characteristics can be formed.

The content of the room temperature solidified resin is 50 parts by mass or more and 300 parts by mass or less, and preferably 100 parts by mass or more and 180 parts by mass or less with respect to 100 parts by mass of the crosslinked hot melt adhesive. When the content of the room temperature solidified resin is at least the lower limit, a laminated core having excellent magnetic properties can be formed. When the content of the room temperature solidified resin is not more than the upper limit value, heat resistance that can guarantee the adhesive strength can be obtained even when the motor generates heat.

Hot-melt adhesives are bonded by heating and melting, and can be made solvent-free, and have the advantage of being able to significantly reduce the components that volatilize during bonding. Furthermore, various properties can be exhibited by molecular design and mixing with various resins. In the crosslinked hot melt adhesive used in this embodiment, by using a polyester urethane resin, which is characterized by high mechanical strength, as a crosslinked type, heat resistance can be obtained even after bonding and high temperature strength can be ensured, so that it can be used for motors. Will be available as. Furthermore, by mixing with a room temperature solidified resin, both core iron loss and heat resistance can be achieved. Further, by combining an aromatic amine having a potential as a curing agent, sufficient coating properties can be ensured, and low-temperature baking and low-temperature adhesion become possible.

The insulating film 3 can be formed, for example, by applying a coating composition for an electromagnetic steel sheet to the surface of a base steel sheet, drying it, and baking it.
The lower limit of the temperature reached during baking is preferably 90 ° C, more preferably 110 ° C. The upper limit of the reached temperature at the time of baking is preferably 180 ° C, more preferably 160 ° C.
The lower limit of the baking time is preferably 5 seconds, more preferably 10 seconds. The upper limit of the baking time is preferably 60 seconds, more preferably 45 seconds.

The upper and lower limit values of the average thickness t1 of the insulating film 3 are set as follows, for example, in consideration of the case where the material 1 is used as the electromagnetic steel sheet 40.
When the material 1 is used as the electrical steel sheet 40, the average thickness t1 of the insulating film 3 (thickness per one side of the electrical steel sheet 40 (material 1)) is the insulation performance and adhesive ability between the electrical steel sheets 40 laminated with each other. Adjust so that can be secured.

In the case of the single-layer insulating coating 3, the lower limit of the average thickness t1 of the insulating coating 3 is preferably 2.0 μm, more preferably 2.5 μm. On the other hand, as the insulating film 3 becomes thicker, the insulating effect saturates. Further, as the insulating film 3 becomes thicker, the proportion of the base steel sheet 2 in the laminated core decreases, and the performance as the laminated core deteriorates. Therefore, the upper limit of the average thickness t1 of the insulating coating 3 is preferably 8.0 μm, more preferably 6.0 μm.
In the case of the insulating coating 3 having a multi-layer structure, the average thickness of the underlying insulating coating can be, for example, 0.3 μm or more and 2.5 μm or less, preferably 0.5 μm or more and 1.5 μm or less. The lower limit of the average thickness of the upper insulating coating can be 2.0 μm, preferably 2.5 μm. The upper limit of the average thickness of the upper insulating coating can be 6.0 μm, preferably 4.5 μm.
The method of measuring the average thickness t1 of the insulating coating 3 in the material 1 is the same as that of the average plate thickness t0 of the material 1, and the thicknesses of the insulating coatings 3 at a plurality of locations can be obtained and obtained as the average of those thicknesses. can.

The upper and lower limit values of the average thickness t1 of the insulating coating 3 in the material 1 can be naturally adopted as the upper and lower limit values of the average thickness t1 of the insulating coating 3 in the electrical steel sheet 40. The method for measuring the average thickness t1 of the insulating coating 3 on the electrical steel sheet 40 is, for example, the following measuring method. For example, among a plurality of electrical steel sheets forming a laminated core, the electrical steel sheet 40 located on the outermost side in the laminated direction (the electrical steel sheet 40 whose surface is exposed in the laminated direction) is selected. On the surface of the selected electrical steel sheet 40, a predetermined position in the radial direction (for example, a position just intermediate (center) between the inner peripheral edge and the outer peripheral edge of the electrical steel sheet 40) is selected. At the selected positions, the thickness of the insulating coating 3 of the electrical steel sheet 40 is measured at four locations (that is, every 90 degrees around the central axis O) at equal intervals in the circumferential direction. The average value of the measured thicknesses at the four locations can be taken as the average thickness t1 of the insulating coating 3.
The reason why the average thickness t1 of the insulating coating 3 was measured on the outermost electromagnetic steel sheet 40 in the laminating direction is that the thickness of the insulating coating 3 is the laminating position along the laminating direction of the electromagnetic steel sheet 40. This is because the insulating film 3 is built so that it hardly changes.

The electromagnetic steel sheet 40 is manufactured by punching the material 1 as described above, and the adhesive core (stator core 21 and rotor core 31) is manufactured by the magnetic steel sheet 40.

(Laminating method of laminated core)
Hereinafter, the description of the laminated core will be returned. As shown in FIG. 3, the plurality of electrical steel sheets 40 forming the stator core 21 are laminated via the insulating coating 3.
The electromagnetic steel sheets 40 adjacent to each other in the stacking direction are adhered over the entire surface by the insulating coating 3. In other words, the surface of the electromagnetic steel sheet 40 facing the stacking direction (hereinafter referred to as the first surface) is the bonding region 41a over the entire surface. However, the electromagnetic steel sheets 40 adjacent to each other in the stacking direction may not be adhered over the entire surface. In other words, the adhesive region 41a and the non-adhesive region (not shown) may coexist on the first surface of the electrical steel sheet 40.

In the present embodiment, the plurality of electrical steel sheets forming the rotor core 31 are fixed to each other by the caulking 42 (dowel) shown in FIG. However, the plurality of electrical steel sheets forming the rotor core 31 may also have a laminated structure fixed by the insulating coating 3 as in the stator core 21.
Further, the laminated core such as the stator core 21 and the rotor core 31 may be formed by so-called rotating stacking.

(Manufacturing method of laminated core)
The stator core 21 is manufactured, for example, by using the manufacturing apparatus 100 shown in FIG. 7. In the following, in explaining the manufacturing method, first, the laminated core manufacturing apparatus 100 (hereinafter, simply referred to as the manufacturing apparatus 100) will be described.
In the manufacturing apparatus 100, while the material 1 is sent out from the coil 1A (hoop) in the direction of the arrow F, the material 1 is punched a plurality of times by the dies arranged on each stage to gradually form the shape of the electromagnetic steel sheet 40. go. Then, the punched electrical steel sheets 40 are laminated and pressurized while raising the temperature. As a result, the electromagnetic steel sheets 40 adjacent to each other in the laminating direction are adhered by the insulating coating 3 (that is, the portion of the insulating coating 3 located in the adhesive region 41a exerts an adhesive ability), and the adhesion is completed.

As shown in FIG. 7, the manufacturing apparatus 100 includes a plurality of stages of punching stations 110. The punching station 110 may have two stages or three or more stages. The punching station 110 of each stage includes a female die 111 arranged below the material 1 and a male die 112 arranged above the material 1.

The manufacturing apparatus 100 further includes a stacking station 140 at a position downstream of the most downstream punching station 110. The laminating station 140 includes a heating device 141, an outer peripheral punching female die 142, a heat insulating member 143, an outer peripheral punching male die 144, and a spring 145.
The heating device 141, the outer peripheral punched female die 142, and the heat insulating member 143 are arranged below the material 1. On the other hand, the outer peripheral punching die 144 and the spring 145 are arranged above the material 1. Reference numeral 21 indicates a stator core.

In the manufacturing apparatus 100 having the above-described configuration, first, the material 1 is sequentially fed from the coil 1A in the direction of the arrow F in FIG. Then, the material 1 is sequentially punched by a plurality of punching stations 110. By these punching processes, the shape of the electromagnetic steel sheet 40 having the core back portion 22 and the plurality of tooth portions 23 shown in FIG. 3 is obtained on the material 1. However, since it is not completely punched at this point, the process proceeds to the next step along the arrow F direction.

Finally, the material 1 is sent out to the laminating station 140, punched out by the outer peripheral punching die 144, and laminated with high accuracy. At the time of this laminating, the electromagnetic steel sheet 40 receives a constant pressing force by the spring 145. By sequentially repeating the punching process and the laminating process as described above, a predetermined number of electrical steel sheets 40 can be stacked. Further, the laminated core formed by stacking the electromagnetic steel sheets 40 in this way is heated to, for example, a temperature of 200 ° C. by the heating device 141. By this heating, the insulating coatings 3 of the adjacent electromagnetic steel sheets 40 are adhered to each other.
The heating device 141 may not be arranged on the outer peripheral punched female die 142. That is, before the electromagnetic steel sheets 40 laminated by the outer peripheral punched female die 142 are adhered, they may be taken out of the outer peripheral punched female die 142. In this case, the outer peripheral punched female die 142 may not have the heat insulating member 143. Further, in this case, the stacked electromagnetic steel sheets 40 before bonding may be sandwiched and held from both sides in the stacking direction by a jig (not shown), and then transported or heated.
The stator core 21 is completed by each of the above steps.

As described above, in the present invention, as a coating composition for electrical steel sheets that forms an insulating film of electrical steel sheets, a specific crosslinked hot melt adhesive and a room temperature solidified resin are combined at a specific ratio. As a result, even if the thickness of the magnetic steel sheet is thin, it is possible to suppress the application of stress strain due to the adhesive component, so that a laminated core having excellent magnetic characteristics (core iron loss) can be formed. Further, since the adhesive strength between the electromagnetic steel sheets is high and the heat resistance is excellent, it is possible to form a laminated core that can secure the adhesive strength even when the motor generates heat.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
The shape of the stator core is not limited to the form shown in the above embodiment. Specifically, the dimensions of the outer diameter and inner diameter of the stator core, the product thickness, the number of slots, the dimensional ratio between the circumferential direction and the radial direction of the tooth portion, the dimensional ratio in the radial direction between the tooth portion and the core back portion, etc. are desired. It can be arbitrarily designed according to the characteristics of the rotary electric machine.

In the rotor in the above embodiment, a set of two permanent magnets 32 form one magnetic pole, but the present invention is not limited to this. For example, one permanent magnet 32 may form one magnetic pole, or three or more permanent magnets 32 may form one magnetic pole.

In the above-described embodiment, the permanent magnet field type motor has been described as an example of the rotary electric machine, but the structure of the rotary electric machine is not limited to this as illustrated below, and various publicly known structures not further exemplified below. The structure of can also be adopted.
In the above-described embodiment, the permanent magnet field type motor has been described as an example of the rotary electric machine, but the present invention is not limited to this. For example, the rotary electric machine may be a reluctance type electric machine or an electromagnet field type electric machine (winding field type electric machine).
In the above-described embodiment, the synchronous motor has been described as an example of the AC motor, but the present invention is not limited to this. For example, the rotary electric machine may be an induction motor.
In the above-described embodiment, the AC motor has been described as an example of the motor, but the present invention is not limited to this. For example, the rotary electric machine may be a DC motor.
In the above-described embodiment, the electric machine has been described as an example of the rotary electric machine, but the present invention is not limited to this. For example, the rotary electric machine may be a generator.

In the above embodiment, the case where the laminated core according to the present invention is applied to the stator core is illustrated, but it can also be applied to the rotor core.
It is also possible to use a laminated core for a transformer instead of a rotary electric machine. In this case, it is preferable to use grain-oriented electrical steel sheets instead of grain-oriented electrical steel sheets.

In addition, it is appropriately possible to replace the constituent elements in the above-described embodiment with well-known constituent elements without departing from the spirit of the present invention, and the above-mentioned modifications may be appropriately combined.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following description.

[material]
The raw materials used are shown below.
(Polyester urethane resin)
PE1: Polyester urethane prepolymer (weight average molecular weight (Mw): 5000)
A polyester polyol (Kurare Co., Ltd.) obtained from terephthalic acid, adipic acid, and 3-methyl-1,5-pentanediol in a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler, a dropping device, and a nitrogen introduction tube. "Kurare Polyol P-2011", Mn = 2040) 500 parts by mass, dimethylolbutanoic acid 15 parts by mass, isophorone diisocyanate 100 parts by mass, and toluene 80 parts by mass were charged and reacted at 90 ° C. for 4 hours under a nitrogen atmosphere. To this, 350 parts by mass of toluene was added to obtain a polyester urethane prepolymer (Mw = 5000, molar ratio (NCO / OH) = 1: 1) solution containing an isocyanate group.

PE2: Polyester urethane prepolymer (Mw: 12000)
A polyester-based urethane prepolymer (Mw = 12000, molar ratio (NCO / OH) = 1: 1) solution containing an isocyanate group was obtained in the same manner as in PE1 except that the reaction time was changed.

PE3: Polyester urethane prepolymer (Mw: 35000)
A polyester-based urethane prepolymer (Mw = 35000, molar ratio (NCO / OH) = 1: 1) solution containing an isocyanate group was obtained in the same manner as in PE1 except that the reaction time was changed.

(Polyester urethane resin)
PO1: Polyester urethane prepolymer (Mw: 5000)
100 parts by mass of isocyanate obtained by mixing 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate at a mass ratio of 8: 2 and 600 parts by mass of polypropylene glycol were mixed at 80 ° C. for 2 hours and then at 100 ° C. for 3 hours. The reaction was carried out to obtain a polyether urethane prepolymer (Mw = 5000, molar ratio (NCO / OH) = 3: 1) solution containing an isocyanate group.

PO2: Polyester urethane prepolymer (Mw: 35000)
A polyether urethane prepolymer (Mw = 35000, molar ratio (NCO / OH) = 3: 1) solution containing an isocyanate group was obtained in the same manner as in PE1 except that the molecular weight of polypropylene glycol was changed.

(Hardener)
H1: Polytetramethylene oxide-di-p-aminobenzoate (MP: 60 ° C)
H2: 3,3'-dichloro-4,4'-diaminophenylmethane (MP: 98 ° C)
H3: Trimethylene-bis (4-aminobenzoate) (MP: 125 ° C)
G1: Xylylenediamine trimer (viscous liquid, MP: less than 0 ° C)
G2: Polytetramethylene oxide-di-p-aminobenzoate (MP: 15 ° C)
G3: Blocked isocyanate (MP: 105 ° C)
G4: dicyandiamide (MP: 210 ° C)

(Room temperature solidified resin)
R1: Rosin derivative resin (softening point: 110 ° C)
R2: Aromatic hydrocarbon resin (softening point: 140 ° C)
R3: Terpene phenol resin (softening point: 160 ° C)
R4: Novolac phenol resin (softening point: 180 ° C)

(Comparative resin)
S1: Terpene resin (softening point: 65 ° C)
S2: Rosin resin (softening point: 82 ° C)
S3: Novolac phenol resin (softening point: 230 ° C)

[Magnetic characteristics]
A non-oriented electrical steel sheet having a thickness of 0.25 mm and a width of 100 mm, which is made of Si: 3.0%, Mn: 0.2%, Al: 0.5%, and the balance is Fe and impurities in mass%, is an electromagnetic steel strip. Manufactured as. The coating composition for electrical steel sheets of each example was applied to both surfaces of the electrical steel strip and baked under the conditions shown in Table 1 to form an insulating film having an average plate thickness t1 of 3 μm.
A rectangular electromagnetic steel sheet having a size of 55 mm × 55 mm was cut out from the electrical steel strip, and 10 sheets of electrical steel sheets were laminated and bonded under the conditions of a steel sheet temperature of 180 ° C., a pressure of 10 MPa, and a pressurizing time of 1 hour to prepare a laminated core. For the obtained laminated core, the single plate magnetic characteristics in the direction perpendicular to the rolling direction and the rolling direction are measured by the single plate magnetic measurement method based on JIS C2556 (2015), and the average value of these values is the magnetic characteristic. Asked as.

[Adhesive strength]
Two rectangular steel sheets having a width of 30 mm and a length of 60 mm are cut out from the electrical steel strip manufactured in the above [magnetic characteristics] test, and the tip portions having a width of 30 mm and a length of 10 mm are overlapped with each other, and the steel plate temperature is 180. A sample was prepared by adhering at ° C., a pressure of 10 MPa, and a pressurization time of 1 hour. The ambient temperature was 25 ° C. or 150 ° C., the shear tensile strength was measured at a tensile speed of 2 mm / min, and the value divided by the adhesive area was taken as the adhesive strength (MPa).

[judgement]
For each example, the judgment was made according to the following criteria.
◯ (excellent): The adhesive strength at 25 ° C. is 5 MPa or more, the adhesive strength at 180 ° C. is 0.5 MPa or more, and the magnetic property is less than 12 W / kg.
Δ (possible): The adhesive strength at 25 ° C. is 4 MPa or more and less than 5 MPa, the adhesive strength at 180 ° C. is 0.5 MPa or more, and the magnetic property is less than 12 W / kg.
X (defective): Does not satisfy any one or more of the adhesive strength at 25 ° C. of 4 MPa or more, the adhesive strength at 180 ° C. of 0.5 MPa or more, and the magnetic property of less than 12 W / kg.

[Examples 1 to 10, Comparative Examples 1 to 11]
Each component was mixed with the composition shown in Table 1 to prepare a coating composition for electrical steel sheet.

Table 1 shows the composition of the coating composition for electrical steel sheets of each example and the baking conditions. Table 2 shows the evaluation results of each example.

As shown in Table 2, in Examples 1 to 10 in which a specific crosslinked hot melt adhesive and a room temperature solidified resin are combined at a specific ratio, the electromagnetic steel sheets are used at both normal temperature (25 ° C) and 150 ° C. The adhesive strength of the laminated core was high, and the magnetic properties of the laminated core were also excellent.
In Comparative Examples 1 to 11 which did not satisfy the conditions such as the type of urethane resin, the softening point and the content of the room temperature solidified resin, the adhesive strength and the magnetic properties at room temperature and 150 ° C. could not be compatible.

[Examples 21 to 26, Comparative Examples 21 to 26]
Next, an example of the influence of the insulating coating when the average plate thickness t0 of the material (electrical steel sheet) changes will be shown. The average thickness t1 of the insulating coating was kept constant at "3 μm", and the average plate thickness t0 of the material was changed by changing the plate thickness of the base steel plate. The raw material of the insulating coating used was the same as in Example 2 or Comparative Example 3. The base steel sheet is a non-oriented electrical steel sheet having a width of 100 mm, which is made of Si: 2.95%, Mn: 0.2%, Al: 0.4%, and the balance is Fe and impurities in mass%. did.
The various evaluation means and the like were the same as the above-mentioned [magnetic properties], [adhesive strength] and [judgment], and only the thickness of the non-oriented electrical steel sheet to be the base steel sheet was changed. The coating composition and baking conditions were the same as in Table 1 and Table 2 for Examples 21 to 25, and the same as those in Table 1 and Comparative Example 3 for Comparative Examples 21 to 25. The evaluation results of each example are shown in Table 3. The "material plate thickness t0" in Table 3 includes the average thickness t1 (3 μm) of the insulating coating.

As shown in Table 3, in both the steel sheet of the example and the steel sheet of the comparative example, the iron loss decreases as the material plate thickness t0 decreases, but the electromagnetic steel sheet having the insulating film according to the present invention has a particularly thin material plate thickness t0. In some cases, the iron loss can be suppressed to be lower than that of the electromagnetic steel sheet of the comparative example. It is considered that this is because, as described above, the insulating coating of the present invention suppresses the generation of stress strain due to curing.

According to the present invention, both magnetic properties and heat resistance can be achieved at the same time. Therefore, the industrial applicability is great.

1 ... Material, 2 ... Base steel plate, 3 ... Insulation film, 10 ... Rotating electric machine, 20 ... Stator, 21 ... Stator core, 40 ... Electromagnetic steel plate.

Claims (6)

It contains a crosslinked hot melt adhesive composed of a polyester urethane resin which is a reaction product of a polyester polyol and a polyisocyanate and a curing agent, and a room temperature solidified resin.
The softening point of the room temperature solidified resin is 100 ° C. or higher and 200 ° C. or lower.
A coating composition for electrical steel sheets, wherein the content of the room temperature solidified resin is 50 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the crosslinked hot melt adhesive. The coating composition for electrical steel sheets according to claim 1, wherein the curing agent is an aromatic amine having a melting point of 50 ° C. or higher and 200 ° C. or lower. An electromagnetic steel sheet having an insulating film coated with the coating composition for electrical steel sheets according to claim 1 or 2 on the surface. The electromagnetic steel sheet according to claim 3, wherein the sheet thickness is 0.50 mm or less. A laminated core in which a plurality of electrical steel sheets according to claim 3 or 4 are laminated and bonded to each other. A rotary electric machine provided with the laminated core according to claim 5.

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