RU2814180C1 - Coating composition for electrical steel sheet, electrical steel sheet with adhesive-coated surface and laminated core - Google Patents

Abstract

FIELD: electrical machines.

SUBSTANCE: invention relates to a coating composition for an electrical steel sheet, to an electrical steel sheet with an adhesive-coated surface, a laminated core. The coating composition contains an epoxy resin, a phenolic hardener (A) and an amine hardener (B), wherein the amine hardener (B) is an aromatic amine, and the amount of the phenolic hardener (A) is 1-40 parts by weight per 100 parts by weight of epoxy resin, and the amount of amine hardener (B) is 0.5-5 parts by mass per 100 parts by mass of epoxy resin.

EFFECT: coating composition for an electrical steel sheet, an electrical steel sheet with an adhesive-coated surface, and a laminated core that are capable of further suppressing stress deformation imparted to the electrical steel sheets and have a heat resistance high enough to maintain adhesive strength even when heat is generated from the motors.

4 cl, 7 dwg, 2 tbl

Description

TECHNICAL FIELD

[0001] The present invention relates to a coating composition for an electrical steel sheet, an electrical steel sheet with an adhesive coated surface, and a laminated core. Priority is claimed by Japanese Patent Application No. 2020-104233, filed June 17, 2020, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] Typically, in the case of laminated core assembly, such as in a motor or transformer using electrical steel sheets, unit iron cores are manufactured by cutting or blanking, and then the individual iron cores are laminated and firmly fixed by bolting, crimping, welding or gluing , thereby obtaining a laminated core. In the strong fixing method such as crimping or welding, the laminated core is subjected to mechanical deformation or thermal deformation, and therefore there are cases where the magnetic loss of the core is deteriorated.

[0003] In regard to such a problem, for example, in Patent Documents 1 to 3, bonding methods that use an insulating coating exhibiting adhesive ability under heat and/or pressure (coating composition for electrical steel sheet) have been proposed.

[List of cited documents]

[Patent Documentation]

[0004] Patent document 1: Unexamined Japanese patent application, first publication 2000-173816

Patent Document 2: PCT Application International Publication No. WO2004/070080

[Patent Document 3: Unexamined Japanese Patent Application First Publication No. 2017-011863

BRIEF DESCRIPTION OF THE INVENTION

Problems solved by the invention

[0005] Laminated cores, in which single iron cores are bonded together using insulating coatings, are not subject to mechanical or thermal deformation and are therefore superior in core magnetic loss. However, in recent years, there has been a need to further improve motor efficiency and further reduction of magnetic core losses has been required.

[0006] Reducing the thickness of electrical steel sheet has been effective in reducing magnetic loss in the core. However, since a decrease in sheet thickness is accompanied by a decrease in the Young's modulus of the electrical steel sheet, it is necessary to prevent stress deformation, which causes deterioration of the magnetic loss in the core, from being imparted to the electrical steel sheet. Additionally, applications such as electric vehicles require high heat resistance, but insulating coatings that do not impart stress deformation to electrical steel sheets are typically soft and have poor heat resistance.

[0007] The present invention has been made in view of the above-described circumstances, and the object of the present invention is to provide a coating composition for an electrical steel sheet, an electrical steel sheet with an adhesive coated surface, and a laminated core, which are capable of further suppressing stress deformation imparted to electrical steel sheets and have high enough heat resistance to maintain adhesive strength even when heat is generated from the engines.

Remedies to solve the problem

[0008] In order to solve the above problems, the present invention provides the following means.

[1] A coating composition for electrical steel sheet according to an aspect of the present invention contains an epoxy resin, a phenolic hardener (A) and one or more amine hardeners (B) selected from an aromatic amine and a dicyandiamide, wherein the amount of the phenolic hardener (A) is 1 -40 parts by mass per 100 parts by mass of epoxy resin, and the amount of amine hardeners (B) is 0.5-5 parts by mass per 100 parts by mass of epoxy resin.

[2] The coating composition for electrical steel sheet according to item [1], in which the mass ratio represented by [amount of phenolic hardener (A)]/[amount of amine hardener (B)] may be from 1 to 20.

[3] The adhesive-coated electrical steel sheet according to an aspect of the present invention has an insulating coating on the surface containing the electrical steel sheet coating composition of [1] or [2], in which the thickness is 0.65 mm or less.

[4] The laminated core in accordance with an aspect of the present invention is formed by lapping two or more electrical steel sheets with an adhesive-coated surface as in [3].

Effects of the invention

[0009] According to the above-described aspects of the present invention, it is possible to provide a coating composition for an electrical steel sheet, an electrical steel sheet with an adhesive coated surface, and a laminated core that are capable of further suppressing stress deformation imparted to the electrical steel sheets and have a heat resistance high enough to maintain adhesive strength even when heat is released from the engines.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a sectional view of a rotating electric machine including a laminated core according to the first embodiment of the present invention.

Fig. 2 is a side view of the laminated core shown in FIG. 1.

Fig. 3 is a sectional view taken along line AA in FIG. 2.

Fig. 4 is a plan view of the material for forming the laminated core shown in FIG. 1.

Fig. 5 is a sectional view taken along line BB in FIG. 4.

Fig. 6 is an enlarged view of part C of FIG. 5.

Fig. 7 is a side view of the manufacturing apparatus used to produce the laminated core shown in FIG. 1.

OPTION FOR IMPLEMENTATION OF THE INVENTION

[0011] Next, a laminated core according to an embodiment of the present invention, a rotating electric machine including the laminated core, and a material forming the laminated core will be described. In the present embodiment, as an example of a rotating electric machine, an electric motor, specifically an AC electric motor, more particularly a synchronous electric motor, and even more specifically a permanent magnet electric motor will be described. This type of electric motor is preferably used, for example, in electric vehicles.

[0012] In addition, the numeric limiting ranges expressed below using the hyphen "-" include a lower limit value and an upper limit value. Numeric values expressed with the word preceding "less" or "more" are not included in numeric ranges.

[0013] As shown in FIG. 1, the rotating electric machine 10 includes a stator 20, a rotor 30, a casing 50, and a rotating shaft 60. The stator 20 and the rotor 30 are housed in the casing 50. The stator 20 is fixed in the casing 50. In the present embodiment, the rotating electric machine 10 is used an internal rotor machine in which the rotor 30 is located radially inside the stator 20. However, as the rotating electric machine 10, an external rotor machine in which the rotor 30 is located outside the stator 20 can be used. Moreover, in the present embodiment, the rotating electric machine 10 is a three-phase AC motor with 12 poles and 18 slots. However, the number of poles, the number of slots, the number of phases and the like may be changed accordingly. The rotating electrical machine 10 can be rotated at a rotation speed of 1000 revolutions per minute (rpm) while applying an excitation current to each phase, for example, with an effective value of 10 A and a frequency of 100 Hz.

[0014] The stator 20 includes a laminated stator core 21 (hereinafter referred to as the stator core) and a winding not shown in the drawing. The stator core 21 includes an annular core back 22 and a plurality of toothed portions (teeth) 23. In the following, the direction along the central axis O of the stator core 21 (or core back 22) is referred to as the axial direction, the radial direction (the direction orthogonal to the central axis O) the stator core 21 (or the core back 22) is referred to as the radial direction, and the circumferential direction (the direction around the central axis O) of the stator core 21 (or the core back 22) is referred to as the circumferential direction.

[0015] The core back 22 is formed with an annular shape in a top view of the stator 20 when viewed in the axial direction. A plurality of teeth 23 project from the inner periphery of the core back 22 in a radially inward direction (toward the central axis O of the core back 22 in the radial direction). A plurality of teeth 23 are arranged at equal angular intervals in the circumferential direction. In the present embodiment, 18 teeth 23 are provided at every 20 degrees of a central angle about the central axis O. The plurality of teeth 23 are formed in mutually equivalent shapes and with mutually equivalent dimensions. Accordingly, the plurality of teeth 23 have mutually identical thickness dimensions. The winding is wound around the teeth 23. The winding may be a concentric winding or a distributed winding.

[0016] The rotor 30 is located radially within 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 with a circular (ring) shape and is located concentrically with the stator 20. The rotating shaft 60 is located in the rotor core 31. The rotating shaft 60 is attached to the rotor core 31. A plurality of permanent magnets 32 are attached to the rotor core 31. In the present embodiment, one set of two permanent magnets 32 forms one magnetic pole. A plurality of permanent magnets 32 are arranged at equal angular intervals in the circumferential direction. In the present embodiment, 12 sets of permanent magnets 32 (a total of 24 permanent magnets) are provided every 30 degrees of the central angle around the central axis O.

[0017] In the present embodiment, a motor with built-in magnets is adopted as the permanent magnet excited motor. The rotor core 31 is formed with a plurality of through holes 33 extending through the rotor core 31 in the axial direction. A plurality of through holes 33 are provided corresponding to the arrangement of a plurality of permanent magnets 32. Each permanent magnet 32 is attached to the rotor core 31 in a state in which it is located in a corresponding through hole 33. Attaching each permanent magnet 32 to the rotor core 31 can be realized, for example, by gluing the outer surface of the permanent magnet 32 and the inner surface of the through hole 33 by means of an adhesive. As a permanent magnet motor, a surface permanent magnet motor can be used instead of a motor with built-in magnets.

[0018] Both the stator core 21 and the rotor core 31 are laminated cores. For example, the stator core 21 is formed by laminating a plurality of electrical steel sheets 40 (electrical steel sheets with an adhesive coated surface) in the laminating direction, as shown in FIG. 2. The lamination 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 set to, for example, 250.0 mm. The inner diameter of the stator core 21 is set to, for example, 165.0 mm. The outer diameter of the rotor core 31 is set to, for example, 163.0 mm. The inner diameter of the rotor core 31 is set to, for example, 30.0 mm. However, these values are given as an example only, and the lamination thickness, outer diameter or inner diameter of the stator core 21 and the lamination 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 end portions of the teeth 23 in the stator core 21. That is, the inner diameter of the stator core 21 is the diameter of an imaginary circle inscribed in the end parts of all teeth 23.

[0019] Each of the electrical steel sheets 40 constituting the stator core 21 and the rotor core 31 is formed, for example, by stamping the material 1, as shown in FIG. 4-6, or the like. The material 1 is a steel sheet (electrical steel sheet) which serves as the base of the electrical steel sheet 40. Examples of material 1 include strip-shaped steel sheet (electrical steel strip), cut-to-length sheet or the like.

[0020] Although the subject of the current description is a laminated core, material 1 will be described below. In the present description, there is a case where the strip-shaped steel sheet that serves as the base of the electrical steel sheet 40 is referred to as material 1. There is a case where the steel sheet, formed in the form used in the laminated core by stamping the material 1 is referred to as electrical steel sheet 40.

[0021] The material 1 is handled in a state in which it is wound into a roll 1A. In the present embodiment, an isotropic electrical steel sheet is used as the material 1. As the isotropic electrical steel sheet, isotropic electrical steel strip in accordance with JIS C 2552:2014 can be used. However, as the material 1, instead of the isotropic electrical steel sheet, an anisotropic electrical steel sheet can be used. In this case, anisotropic electrical steel strip in accordance with the JIS C 2553:2019 standard can be used as an anisotropic electrical steel sheet. In addition, thin strip of isotropic electrical steel or thin strip of anisotropic electrical steel in accordance with JIS C 2558:2015 can be used.

[0022] The upper and lower limit values of the average thickness t0 of the sheet of material 1 are set, for example, as described below, taking into account the case where the material 1 is used as the electrical steel sheet 40. As the material 1 becomes thinner, the cost of manufacturing the material 1 increases. Therefore, taking into account the manufacturing cost, the lower limit value of the average thickness t0 of the sheet of 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 costs become favorable; however, in the case where the material 1 is used as the electrical steel sheet 40, the eddy current loss increases and the magnetic core loss deteriorates. Therefore, taking into account the magnetic loss in the core and the manufacturing cost, the upper limit value of the average thickness t0 of the sheet of material 1 is 0.65 mm, preferably 0.35 mm, and more preferably 0.30 mm. For example, a value of 0.20 mm may satisfy the above-described range of the average thickness t0 of the sheet of material 1.

[0023] The average thickness t0 of the sheet of material 1 includes not only the thickness of the steel base sheet 2 as described below, but also the thickness of the insulating coating 3. Moreover, the method for measuring the average thickness t0 of the sheet of material 1 is, for example, described below measurement method. For example, in the case where the material 1 is wound in the form of a roll 1A, at least a portion of the material 1 is unwound in the form of a flat sheet. In the material 1 unwound in the form of a flat sheet, a predetermined position in the longitudinal direction of the material 1 is selected (for example, a position distant from one end edge of the material 1 in the longitudinal direction by 10% of the total length of the material 1). In this selected position, the material 1 is divided into five regions in its width direction. The thickness of the sheet of material 1 is measured at four places, which become the boundaries of these five areas. The average value of the sheet thicknesses at four places can be defined as the average thickness t0 of the sheet of material 1.

[0024] Needless to say, the upper and lower limit values of the average thickness t0 of the sheet material 1 can also be used as the upper and lower limit values of the average thickness t0 of the electrical steel sheet 40. As a method for measuring the average thickness t0 of the electrical steel sheet 40, for example, the following measurement method is given. For example, the lamination thickness of a laminated core is measured at four locations at equal intervals in the circumferential direction (that is, every 90 degrees around the central axis O). Each of the fusion thicknesses measured at four places is divided by the number of laminated electrical steel sheets 40, thereby calculating the thickness per sheet. The average value of the sheet thicknesses at four places can be determined as the average thickness t0 of the electrical steel sheet 40.

[0025] As shown in FIG. 5 and fig. 6, the material 1 includes a steel base sheet 2 and insulation coatings 3. The material 1 is formed by covering both surfaces of the strip-shaped steel base sheet 2 with insulating coatings 3. In the present embodiment, most of the material 1 is formed from the steel base sheet 2 , and on the surface of the steel base sheet 2, insulating coatings 3 are applied, thinner than the steel base sheet 2.

[0026] The chemical composition of the base steel sheet 2 contains, by weight. %, from 2.5% to 4.5% Si, as described below. When the chemical composition is in this range, it is possible to set the yield strength of material 1 (electrical steel sheet 40) to, for example, 380 MPa or more and 540 MPa or less.

[0027] Si: 2.5% to 4.5%

Al: from 0.001% to 3.0%

Mn: from 0.05% to 5.0%

Rest: Fe and impurities

[0028] When the material 1 is used as the electrical steel sheet 40, the insulating coating 3 exhibits an insulating characteristic between the electrical steel sheets 40 adjacent to each other in the laminating direction. Moreover, in the present embodiment, the insulating coating 3 has adhesive ability and glues the electrical steel sheets 40 adjacent to each other in the laminating direction. The insulating coating 3 can be made in the form of a single layer or multiple layers. More specifically, for example, the insulating coating 3 may be formed as a single layer having both insulating property and adhesive property, or may be formed as a plurality of layers including an underlying insulating coating having excellent insulating property and an overlying insulating coating with excellent adhesion characteristics. The term "adhesiveness of the insulating coating 3" in the present embodiment means the ability to exhibit adhesive strength of a specified or higher value under specified temperature conditions in a laminated stack consisting of a plurality of laminated electrical steel sheets 40 with an insulating coating 3 disposed therebetween.

[0029] In the present embodiment, the insulating coatings 3 completely cover both surfaces of the steel base sheet 2 without gaps. However, some of the insulating coatings 3 may cover both surfaces of the steel base sheet 2 at a gap, provided that the above-described insulating property or adhesive ability is ensured. In other words, some of the insulation coatings 3 may be provided discontinuously on the surface of the base steel sheet 2. However, to ensure insulation performance, it is necessary that both surfaces of the base steel sheet 2 be covered with insulation coatings 3 so that both surfaces of the base steel sheet 2 were not open. Specifically, in the case where the insulating coating 3 does not have an underlying insulating coating having excellent insulating performance and is formed as a single layer having both insulating performance and adhesive ability, the insulating coating 3 must be formed over the entire surface of the base steel sheet 2 without gaps. On the contrary, in the case where the insulating coating 3 is formed as a plurality of layers including an underlying insulating coating having excellent insulating property and an overlying insulating coating having excellent adhesive property, both the insulating property and the adhesive property are satisfactory not only when the underlying insulating coating and the overlying insulating coating are formed on the entire surface of the base steel sheet 2 without gaps, but also when the underlying insulating coating is formed on the entire surface of the base steel sheet without gap, and the overlying insulating coating is provided discontinuously.

[0030] The coating composition constituting the underlying insulation coating is not particularly limited, but, for example, a conventional treatment agent such as a chromic acid-containing treatment agent or a phosphoric acid-containing treatment agent can be used.

[0031] An insulating coating having an adhesive property is formed by applying a coating composition for electrical steel sheet described below to a steel base sheet. The insulation coating having an adhesive property is, for example, an insulation coating formed as a single layer having an insulating property and an adhesive property, or an overlying insulation coating that is provided on an underlying insulation coating. The adhesive insulation coating is in an uncured state or semi-cured state (Stage B) before heat and pressure bonding during manufacture of the laminated core, and exhibits adhesiveness by heating during heat and pressure bonding, causing a curing reaction to occur.

[0032] The insulating coating 3 contains the coating composition for the electrical steel sheet of the present embodiment. The coating composition for electrical steel sheet contains an epoxy resin and an epoxy resin hardener.

[0033] The epoxy resin can be used without particular limitation, provided that the epoxy resin has two or more epoxy groups in the molecule. Examples of such epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, triphenylmethane type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, epoxy resin type glycidylamine, hydantoin-type epoxy resin, isocyanurate-type epoxy resin, acrylic acid-modified epoxy resin (epoxyacrylate), phosphorus-containing epoxy resin, halides thereof or hydrogenated products thereof (brominated epoxy resin, etc.) and the like. These epoxy resins can be used individually, or two or more epoxy resins can be used in combination.

[0034] The amount of epoxy resin is, for example, preferably 30-90 wt. %, more preferably 40-80 wt. %, and even more preferably 50-70 wt. % of the total weight of the coating composition for electrical steel sheet. When the amount of epoxy resin is equal to or greater than the above-described lower limit value, the adhesive strength of the electrical steel sheets 40 can be further enhanced. When the amount of epoxy resin is equal to the above-described upper limit value or less, stress deformation in the electrical steel sheet 40 can be further suppressed.

[0035] Epoxy resin curing agents can be classified into room temperature curing (1° C. to 30° C.), heat curing, and others (photo curing, etc.). Heat-curing epoxy resin hardener can be used as an epoxy resin hardener for adhesive coating (insulation coating). Examples of the heat-curing epoxy resin hardener include aromatic amine, phenolic hardener, acid anhydride hardener, dicyandiamide and the like.

[0036] The epoxy resin hardener of the present embodiment contains a phenolic hardener (A) and an amine hardener (B).

[0037] Examples of the phenolic curing agent (A) include phenol-novolac resin, cresol-novolac resin, bisphenol-novolac resin, triazine-modified phenol-novolac resin, phenol-resol resin, cresol-naphthol-formaldehyde condensation product and the like. Phenolic hardeners (A) can be used individually, or two or more phenolic hardeners (A) can be used in combination.

[0038] The amount of phenolic hardener (A) is 1-40 parts by mass per 100 parts by mass of epoxy resin. The lower limit of the amount of phenolic hardener (A) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and more preferably more than 15 parts by mass. In addition, the upper limit of the amount of phenolic hardener (A) is preferably 35 parts by mass or less, and more preferably 30 parts by mass or less. When the amount of phenolic hardener (A) is equal to the above-described lower limit value or more, the heat resistance of the coating composition for the electrical steel sheet can be further improved. When the amount of phenolic hardener (A) is equal to the above-described upper limit value or less, the stress deformation that is imparted to the electrical steel sheet 40 can be further suppressed.

[0039] The amine hardener (B) is one or more selected from the group consisting of an aromatic amine and a dicyandiamide. In the present embodiment, when the amine hardener (B) is used as the epoxy resin hardener, it is possible to further suppress the stress deformation that is imparted to the electrical steel sheet 40, and therefore, it is possible to significantly improve the magnetic characteristics of the electrical steel sheet 40. From this point of view, at least an aromatic amine is preferably used as the amine curing agent (B).

[0040] Examples of the aromatic amine include meta-xylylenediamine, meta-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone and the like.

[0041] Dicyandiamide is also known as a latent hardener. The latent hardener can be stably stored at room temperature when mixed with epoxy resin, and has the ability to quickly cure resin compositions under the influence of heat, light, pressure and the like. When using dicyandiamide, it is preferable to use the dicyandiamide together with a curing accelerator. Examples of the curing accelerator include tertiary amines, imidazoles, aromatic amines and the like. Amine hardeners (B) can be used individually, or two or more amine hardeners (B) can be used in combination.

[0042] The amount of amine hardener (B) is 0.5-5.0 parts by mass per 100 parts by mass of epoxy resin. The lower limit of the amount of amine hardener (B) is preferably 1.0 parts by mass or more, more preferably 2.0 parts by mass or more, and even more preferably 2.5 parts by mass or more. In addition, the upper limit of the amount of the amine curing agent (B) is preferably 4.5 parts by mass or less, and more preferably 4.0 parts by mass or less. When the amount of amine hardener (B) is equal to the above-described lower limit value or more, the stress deformation that is imparted to the electrical steel sheet 40 can be further suppressed. When the amount of amine hardener (B) is equal to the above-described upper limit value or less, the adhesive strength of the electrical steel sheet 40 can be further enhanced.

[0043] The weight ratio represented as [amount of phenolic hardener (A)]/[amount of amine hardener (B)] (hereinafter also referred to as “A/B ratio”) is preferably from 1.0 to 20.0. The A/B ratio is preferably 5.0 or more, even more preferably more than 10.0, and especially preferably more than 15.0. When the A/B ratio is within the above-described numerical range, stress deformation suppression and heat resistance can be satisfied favorably.

[0044] The epoxy resin hardener of the present embodiment may contain an epoxy resin hardener (D) other than the phenolic hardener (A) and amine hardeners (B).

[0045] Examples of other epoxy resin hardener (D) include acid anhydride hardener, aliphatic polyamine, modified amine, polyamidoamine, secondary amine, tertiary amine, imidazoles, polymer captans, hydrazide compound and the like. These other epoxy resin hardeners (D) can be used individually, or two or more epoxy resin hardeners (D) can be used in combination.

[0046] Examples of the acid anhydride curing agent include phthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl nadicanhydride, chloroendic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic acid anhydride, ethylene glycol bis(anhydrotrimellitate), anhydride methylcyclohexene-tetracarboxylic acid, trimellitic anhydride , azelaic acid polyanhydride and the like.

[0047] Examples of the aliphatic polyamine include diethylenetriamine, triethylenetetramine, dipropylene diamine, diethylaminopropylamine and the like.

[0048] Examples of polyamidoamine include polyamide resins obtained by condensation of a dicarboxylic acid and an aliphatic polyamine, and the like.

[0049] Examples of the dicarboxylic acid include succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexahydrophthalic acid and the like.

[0050] Examples of the modified amine include polyamine adduct with epoxy resin (amine adduct), ketimine and the like.

[0051] Examples of the secondary amine include piperidine and the like. Examples of the tertiary amine include N,N-dimethylpiperazine, triethylenediamine, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol and the like.

[0052] Examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitic acid and the like.

[0053] Examples of polymer captans include liquid polymer captan, polysulfide resin and the like.

[0054] Examples of the hydrazide compound include adipic acid dihydrazide, isophthalic acid dihydrazide, sebacic acid dihydrazide, salicylic acid hydrazide and the like.

[0055] The amount of the other epoxy resin hardener is preferably 3 parts by mass or less per 100 parts by mass of epoxy resin.

[0056] The coating composition for electrical steel sheet of the present embodiment may contain a component other than an epoxy resin and an epoxy resin hardener (hereinafter also referred to as an "optional component"). Examples of the optional component include a curing accelerator other than the above-described epoxy resin hardener (curing catalyst), an emulsifier, a defoamer, a leveling agent, a viscosity regulator, a preservative and the like. Examples of the emulsifier include a nonionic surfactant and the like. Examples of the defoamer include silicone-based defoamer and the like. Examples of the leveler include an acrylic resin-based leveler, a silicone-based leveler or the like. Examples of the viscosity regulator include clay-based silicate such as bentonite or hectorite and the like. Examples of the preservative include an isothiazolinone derivative preservative and the like.

[0057] In the case where the coating composition for the electrical steel sheet of the present embodiment contains an optional component, the amount of the optional component is preferably 0.01 to 5 parts by mass per 100 parts by mass of epoxy resin.

[0058] The coating composition for the electrical steel sheet of the present embodiment is applied to the electrical steel sheet and then dried, thereby obtaining an insulating coating 3. During the coating of the electrical steel sheet, the coating composition for the electrical steel sheet of the present embodiment is applied and preferably baked .

[0059] The temperature achieved during firing is, for example, preferably 120°C to 220°C, more preferably 130°C to 210°C, and even more preferably 140°C to 200°C. When the achieved temperature is equal to the above-described lower limit value or higher, the coating composition for the electrical steel sheet is sufficiently adhered to the electrical steel sheet, and peeling is suppressed. When the temperature achieved is equal to or lower than the above-described upper limit value, it is possible to suppress the curing of the epoxy resin and maintain the adhesiveness of the coating composition for the electrical steel sheet.

[0060] The burning time during firing is, for example, preferably 5-60 seconds, more preferably 10-30 seconds, and even more preferably 10-20 seconds. When the burning time is equal to the above-described lower limit value or longer, the coating composition for the electrical steel sheet is sufficiently adhered to the electrical steel sheet, and peeling is suppressed. When the burning time is equal to the above-described upper limit value or shorter, it is possible to suppress the curing of the epoxy resin and maintain the adhesiveness of the coating composition for the electrical steel sheet.

[0061] The upper and lower limit values of the average thickness t1 of the insulating coating 3 can be set, for example, as described below, taking into account the case where the material 1 is used as the electrical steel sheet 40. In the case where the material 1 is used as the electrical steel sheet 40, the average thickness t1 of the insulating coating 3 (thickness per surface of the electrical steel sheet 40 (material 1)) is adjusted so that the insulating performance and adhesive ability between laminates can be guaranteed. together with sheets of 40 electrical steel.

[0062] In the case of the insulating coating 3 made as a single layer, the average thickness t1 of the insulating coating 3 (thickness per surface of the electrical steel sheet 40 (material 1)) can be set to, for example, 1.5 μm or more and 8.0 µm or less. In the case of the insulating coating 3 made of multiple layers, the average thickness of the underlying insulating coating can be set to, for example, 0.3 μm or more and 2.5 μm or less, and is preferably 0.5 μm or more and 1. 5 microns or less. The average thickness of the overlying insulating coating can be set to, for example, 1.5 µm or more and 8.0 µm or less. As a method for measuring the average thickness t1 of the insulating coating 3 in the material 1, with the same concept of the average thickness t0 of the sheet of the material 1, the thicknesses of the insulating coating 3 are measured at a plurality of places, and the average of these thicknesses can be obtained.

[0063] The upper and lower limit values of the average thickness t1 of the insulating coating 3 in the material 1 can also be used as the upper and lower limit values of the average thickness t1 of the insulating coating 3 in the electrical steel sheet 40.

[0064] As a method for measuring the average thickness t1 of the insulating coating 3 in the electrical steel sheet 40, for example, the following measurement method is used. For example, among a plurality of electrical steel sheets forming a laminated core, an electrical steel sheet 40 located outermost in the fusion direction (the electrical steel sheet 40 whose surface is exposed in the fusion direction) is selected. On the surface of the selected electrical steel sheet 40, a predetermined position in the radial direction is selected (for example, a position exactly in the middle (center) between the inner peripheral edge and the outer peripheral edge in the electrical steel sheet 40). At the selected position, the thickness of the insulating coating 3 of the electrical steel sheet 40 is measured at four places at equal intervals in the circumferential direction (that is, every 90 degrees around the central axis O). The average value of the measured thicknesses in four places can be taken as the average thickness t1 of the insulating coating 3.

[0065] The reason for measuring the average thickness t1 of the insulating coating 3 in the electrical steel sheet 40 located outermost in the fusion direction as described above is that the insulating coating 3 is carefully obtained so that the thickness of the insulating coating 3 practically does not change with the position fusion in the direction of fusion of electrical steel sheet 40.

[0066] The electrical steel sheets 40 are manufactured by stamping the above-described material 1, and a laminated core (stator core 21 or rotor core 31) is manufactured using the electrical steel sheets 40.

[0067] Next, the laminated core will be described again. A plurality of electrical steel sheets 40 forming the stator core 21 are laminated with an insulating coating 3 disposed therebetween, as shown in FIG. 3.

[0068] The electrical steel sheets 40 adjacent to each other in the laminating direction are adhered to each other along all surfaces by the insulating coating 3. In other words, in general, the entire surface of the electrical steel sheet 40 in the laminating direction (hereinafter referred to as the first surface) forms adhesive region 41a. In this case, the electrical steel sheets 40 adjacent to each other in the direction of lamination may not adhere to each other over all surfaces. In other words, on the first surface of the electrical steel sheet 40, an adhesive region 41a and a non-adhesive region (not shown) may be present in a mixed manner.

[0069] In the present embodiment, a plurality of electrical steel sheets forming the rotor core 31 are fastened to each other by fasteners 42 (dowels) shown in FIG. 1. However, the plurality of electrical steel sheets forming the rotor core 31 may also have a laminated structure in which the electrical steel sheets are bonded with an insulating coating 3 as in the stator core 21. In addition, a laminated core such as a stator core 21 or a rotor core 31 may be formed by so-called rotary laying.

[0070] The stator core 21 is manufactured, for example, using the manufacturing apparatus 100 shown in FIG. 7. In the following, when describing the manufacturing method, the laminated core manufacturing apparatus 100 (hereinafter simply referred to as the manufacturing apparatus 100) will be described first.

[0071] In the production apparatus 100, the material 1 is gradually formed into the shape of an electrical steel sheet 40 by performing stamping multiple times at each stage while feeding in the direction of arrow F from the roll (steel sheet) 1A. In addition, the stamped electrical steel sheets 40 are laminated and pressed when heated. As a result, the electrical steel sheets 40 adjacent to each other in the laminating direction are glued together by the insulating coatings 3 (that is, the part of the insulating coating 3 that is located in the adhesive region 41a is caused to exhibit adhesive ability), and adhesion is performed.

[0072] As shown in FIG. 7, the manufacturing apparatus 100 includes a plurality of stages with stamping stations 110. The number of stages with stamping stations 110 may be two or more. Each stamping station stage 110 includes a die 111 located below the material 1 and a die 112 located above the material 1.

[0073] The production device 100 further includes a blending station 140 at a position downstream of the most recent stamping station 110. This batching station 140 includes a heating device 141, an outer shape die 142, a thermal insulation element 143, an outer shape die 144, and a spring 145. The heating device 141, the outer shape die 142, and the insulating element 143 are located below the material 1. On the other hand, the die 144 for giving the outer shape and the spring 145 are located above the material 1. The reference numeral 21 indicates the stator core.

[0074] In the production device 100 configured as described above, first, material 1 is sequentially fed from the roll 1A in the direction of arrow F in FIG. 7. In addition, stamping is sequentially performed on this material 1 through a plurality of stages with stamping stations 110. This stamping gives the shape of an electrical steel sheet 40 having a core back 22 and a plurality of those shown in FIG. 3 teeth 23 obtained in material 1. However, the material is not completely stamped at this point and therefore moves to the next step in the direction of arrow F.

[0075] In addition, finally, the material 1 is supplied to the batching station 140 and is punched out by a die 144 to give an external shape, and the punched products are blended. In this lamination, the electrical steel sheet 40 receives a certain compressive force from the spring 145. The stamping step and the laminating step that were described above are repeated sequentially, whereby a predetermined number of electrical steel sheets 40 can be laid. In addition, the laminated stack formed by stacking the electrical steel sheets 40 as described above is heated, for example, to a temperature of 200° C. by the heating device 141. This heating causes the insulating coatings 3 of the electrical steel sheets 40 adjacent to each other to adhere to each other. friend (adhesion stage).

[0076] The heating device 141 may not be located in the matrix 142 to provide external shape. That is, the electrical steel sheets 40 laminated with the outer-shaping die 142 can be taken out from the outer-shaping die 142 before being bonded to each other. In this case, the thermal insulation element 143 may not be present in the die-cutting matrix 142 to provide the external shape. Moreover, in this case, the stacked electrical steel sheets 40 before being bonded to each other can be transported or heated in a state of being held pressed on both sides in the laminating direction by a clamping device not shown in the drawing. As a result of the above steps, manufacturing of the stator core 21 is completed.

[0077] The heating temperature in the adhesion step is, for example, preferably 120°C to 250°C, more preferably 150°C to 230°C, and even more preferably 200°C to 220°C. If the heating temperature is equal to the above-described lower limit value or higher, the insulating coatings 3 are sufficiently cured, and the adhesive strength of the laminated core can be further enhanced. If the heating temperature is equal to or lower than the above-described upper limit value, thermal deterioration of the insulating coating 3 can be suppressed, and the adhesive strength of the laminated core can be further improved.

[0078] The heating time for the adhesion step depends on the size of the laminated core or the heating method, but is, for example, preferably 30-120 minutes, more preferably 45-100 minutes, and even more preferably 60-80 minutes. If the heating time is equal to the above-described lower limit value or longer, the insulating coatings 3 are sufficiently cured, and the adhesive strength of the laminated core can be further enhanced. If the heating time is equal to or shorter than the above-described upper limit value, thermal deterioration of the insulating coating 3 can be suppressed, and the adhesive strength of the laminated core can be further enhanced.

[0079] During the bonding of the insulating sheets 3 to each other, the insulating sheets 3 may be bonded to each other by pressing the laminated stack.

[0080] The pressure during pressing of the laminated stack is, for example, preferably 2-50 MPa, more preferably 3-30 MPa, and even more preferably 4-20 MPa. If the pressure during pressing of the laminated stack is equal to or higher than the above-described lower limit value, the insulating coatings 3 are sufficiently adhered to each other, and the adhesive strength of the laminated core can be further enhanced. If the pressure at the time of pressing the laminated stack is equal to or lower than the above-described upper limit value, it is possible to suppress the protrusion of the insulating coating 3 from the end portion, and the lining accuracy of the laminated core can be further improved.

[0081] The pressing time during pressing of the laminate stack is, for example, preferably 3-120 minutes, more preferably 10-100 minutes, and even more preferably 30-80 minutes. When the pressing time is equal to the above-described lower limit value or longer, the insulating coatings 3 are sufficiently adhered to each other, and the adhesive strength of the laminated core can be further enhanced. When the pressing time is equal to or shorter than the above-described upper limit value, it is possible to suppress the protrusion of the insulating coating 3 from the end portion, and the laminating accuracy of the laminate core can be further improved.

[0082] So far, one embodiment of the present invention has been described. However, the technical scope of the present invention is not limited to this embodiment only, and various modifications can be made within the spirit of the present invention.

[0083] For example, the shape of the stator core 21 is not limited to only the shape described in this embodiment. Specifically, the dimensions of the outer diameter and the inner diameter, the lamination thickness of the stator core 21, the number of slots, the size ratio of the tooth 23 between the circumferential direction and the radial direction, the size ratio in the radial direction between the tooth 23 and the core back 22 and the like can be arbitrarily designed depending on desirable characteristics of rotating electrical machines.

[0084] In the rotor 30 in this embodiment, one set of two permanent magnets 32 forms one magnetic pole, but the present invention is not limited to this variety. For example, one permanent magnet 32 may form one magnetic pole, or three or more permanent magnets 32 may form one magnetic pole.

[0085] In this embodiment, a permanent magnet electric motor has been described as an example of the rotating electric machine 10, but the structure of the rotating electric machine 10 is not limited to this, as provided by the following examples, and many different well-known structures can be used, which are not provided as illustrative examples below. In this embodiment, a permanent magnet motor has been described as an example of the rotating electric machine 10, but the present invention is not limited to this. For example, the rotating electric machine 10 may be a reluctance-type electric motor or an electromagnetic-excited electric motor (winding-type electric motor). In this embodiment, a synchronous electric motor has been described as an example of an AC motor, but the present invention is not limited to this. For example, the rotating electrical machine 10 may be an induction motor. In this embodiment, an AC electric motor has been described as an example of the rotating electric machine 10, but the present invention is not limited to this. For example, the rotating electrical machine 10 may be a DC motor. In this embodiment, an electric motor has been described as an example of the rotating electric machine 10, but the present invention is not limited to this. For example, the rotating electrical machine 10 may be an electric generator.

[0086] Additionally, it is possible to correspondingly replace any of the constituent elements in this embodiment with well-known constituent elements within the spirit of the present invention, and the above-described modification examples can be suitably combined with each other.

Examples

[0087] Next, the effect of one aspect of the present invention will be more specifically described using examples and comparative examples, but the conditions in the examples are only examples of conditions adopted to confirm the feasibility and effect of the present invention, and the present invention is not limited to the following examples. The present invention may employ a variety of conditions within the scope of the present invention, provided that the object of the present invention is achieved.

[Examples 1-9 and Comparative Examples 1-11]

[0088] Sheets of isotropic electrical steel with a thickness of 0.25 mm and a width of 100 mm were produced, consisting of, by weight. %, Si: 3.0%, Mn: 0.2%, Al: 0.5%, and the rest is Fe and impurities. The epoxy resin compositions shown in Table 1 were used as coating compositions for the electrical steel sheet.

[0089] The epoxy resin composition was applied under the firing conditions shown in Table 1 so that the thickness of the insulating coatings reached 3 μm on average. Specifically, first, a single sheet of 55 mm×55 mm was cut from an isotropic electrical steel sheet, and the single sheet was stamped into a ring mold with an outer diameter of 300 mm and an inner diameter of 240 mm. Next, the electrical steel sheet coating composition was applied to the surface of the single sheet, and then the two single sheets were overlapped and pressed together, thereby creating a laminated stack. As the pressing conditions, the temperature of the steel sheet was set to 200°C, the pressure was set to 10 MPa, and the pressing time was set to 1 hour.

<Magnetic characteristic measurement>

[0090] Magnetic performance was measured using a laminated stack in a single sheet tester based on JIS C 2556:2015. As a magnetic characteristic (magnetic property), “W 10/400” (W/kg) was assessed as magnetic losses. "W 10/400" is the magnetic loss when the frequency is 400 Hz and the maximum magnetic flux density is 1.0 Tesla. Regarding the magnetic performance evaluation criteria, in the case where W10/400 were set to 12.0 W/kg or less, and W10/400 were 12.0 W/kg or less, the magnetic performance was judged to not deteriorate (marked as "good" in Table 2).

<Measuring Adhesive Strengths>

[0091] Shear adhesive strengths were measured in the following manner. First, two single sheets with dimensions of 30 mm × 60 mm were cut from a sheet of isotropic electrical steel. Next, the coating composition for the electrical steel sheet was applied to their surfaces, and the two single sheets on which the coating composition was applied were applied so as to overlap 30 mm × 10 mm and pressed, thereby creating a measurement sample. As the pressing conditions, the temperature of the steel sheet was set to 200°C, the pressure was set to 10 MPa, and the pressing time was set to one hour. The resulting sample was stretched using a tensile tester in an atmosphere where the atmospheric temperature was 25°C, and in an atmosphere where the atmospheric temperature was 150°C, the maximum loads (N) applied before peeling two single sheets from each other were measured, and the numerical values obtained by dividing this maximum load (N) by the bonding area were taken as the adhesive strengths at the corresponding temperatures.

[0092] In Table 1, the types of individual components of the coating compositions for electrical steel sheet are as described below.

<Epoxy resins>

E1: Bisphenol A type epoxy resin

E2: Bisphenol F type epoxy resin

E3: Triphenylmethane type epoxy resin

[0093] <Phenolic hardeners (A) (hardeners A)>

A1: Phenol resol resin

A2: Phenol novolac resin

A3: Cresol-naphthol-formaldehyde condensation product

<Comparative components of hardener A>

C1: Triethylenetetramine

C2: Methylhexahydrophthalic anhydride

[0094] <Amine Hardeners (B) (Hardeners B)>

B1: Meta-xylylenediamine

B2: Diaminodiphenylmethane

B3: Dicyandiamide

<Other Epoxy Hardeners (D)>

D1: Adipic acid dihydrazide

D2: Amine adduct (melting point: 100°C, number average molecular weight: 1500)

[0095] <Optional Components>

Emulsifier: nonionic surfactant (polyoxyethylene alkyl ether)

Defoamer: Silicone based defoamer (polydimethylsilt ocean based compound type defoamer)

[0096] <Definition>

Based on the results of magnetic performance measurement and adhesion strength measurement, magnetic loss and thermal resistance were evaluated based on the following evaluation standards. Small magnetic losses mean that the stress deformation imparted to the electrical steel sheets is suppressed. The measurement results and evaluation determinations are shown in Table 2. In the table, values outside the scope of the invention are underlined.

[0097] <Evaluation Standards>

"Good": The adhesive strength at 150°C is 0.5 MPa or higher, and the magnetic loss is 12.0 W/kg or less.

“Bad”: adhesive strength at 150°C is less than 0.5 MPa, and magnetic loss is more than 12.0 W/kg.

[0100] As shown in Table 2, in Examples 1 to 9 to which the present invention was applied, the adhesive strengths at 150°C were 0.5 MPa or higher, the magnetic losses were 12.0 W/kg or less, and the determinations were "Fine".

[0101] On the other hand, in Comparative Examples 1 and 2, where the amount of phenolic hardener (A) was outside the scope of the present invention, the magnetic loss was greater than 12.0 W/kg, and the determinations were “Poor”. In Comparative Examples 3 to 6, where the amount of amine curing agent (B) was outside the scope of the present invention, the magnetic loss was greater than 12.0 W/kg and the determinations were “Poor”. In Comparative Examples 7 and 8, where an aliphatic polyamine or an acid anhydride curing agent was used instead of a phenolic hardener (A), the magnetic loss was greater than 12.0 W/kg and the determinations were “Poor”. In Comparative Examples 9 and 11, where the phenolic hardener (A) was not contained, the adhesive strengths at 150° C. were lower than 0.5 MPa and the determinations were “Poor”. In Comparative Example 10, in which the amine hardener (B) was not contained, the magnetic loss was greater than 12.0 W/kg, and the determination was "Poor".

[0102] Based on the above-described results, it has been found that according to the coating composition for the electrical steel sheet of the present invention, the stress deformation that is imparted to the electrical steel sheets is suppressed, and the heat resistance is high enough to maintain adhesive strength even when heat is generated from the motors .

[Brief description of reference items]

[0103] 10 Rotating electric machine

20 Stator

21 Glued-laminated stator core

30 Rotor

40 Electrical steel sheet

50 Casing

60 Rotating shaft

Claims (9)

1. A coating composition for electrical steel sheet, containing: epoxy resin; phenolic hardener (A); And amine hardener (B), wherein the amine hardener (B) is an aromatic amine, wherein the amount of phenolic hardener (A) is 1-40 parts by mass per 100 parts by mass of epoxy resin, and the amount of amine hardener (B) is 0.5-5 parts by mass per 100 parts by mass of epoxy resin. 2. The coating composition for electrical steel sheet according to claim 1, wherein the mass ratio represented as [amount of phenolic hardener (A)]/[amount of amine hardener (B)] is 1-20. 3. An electrical steel sheet having an adhesive-coated surface, having on the surface an insulating coating containing a coating composition for an electrical steel sheet according to claim 1 or 2, wherein the thickness of the sheet is 0.65 mm or less. 4. Laminated core formed by laminating two or more sheets of electrical steel with an adhesive-coated surface according to claim 3.

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