Electromagnetic steel sheet with adhesive film, laminated iron core, and method for producing same

Abstract

This electromagnetic steel sheet with an adhesive film has an electromagnetic steel sheet and an adhesive film provided on at least a portion of one or both surfaces of the electromagnetic steel sheet, and is characterized in that: the adhesive film contains a crosslinkable thermoplastic resin A and a thermoplastic resin B other than the crosslinkable thermoplastic resin A, and has a glass transition temperature of 45-80 DEG C; and the melt flow rate at 100 DEG C is 1-25 g / 10 min.

Description

Technical Field

[0001] This disclosure relates to electromagnetic steel sheets with adhesive coatings, laminated iron cores, and methods for manufacturing the same.

[0002] This application claims priority based on Japanese Patent Application No. 2023-163609, filed on September 26, 2023, the contents of which are incorporated herein by reference. Background Technology

[0003] Traditionally, the iron cores used in rotating motors and other applications were constructed using a "stacked iron core" made by layering multiple electromagnetic steel plates. These multiple electromagnetic steel plates were fixed together by methods such as welding, riveting, bolting, and bonding.

[0004] However, in the process of fixing multiple electromagnetic steel plates using welding, riveting, and bolting, mechanical stress, thermal stress, and interlayer short circuits are easily generated during processing. As a result, the magnetic properties of the electromagnetic steel plates deteriorate, making it difficult to fully utilize the performance of the laminated iron core.

[0005] On the other hand, in the fixing of multiple electromagnetic steel plates using an adhesive method, electromagnetic steel plates with an adhesive coating are used. By heating and pressurizing, the adhesive coating is cured to exhibit adhesive ability, thereby bonding multiple electromagnetic steel plates together.

[0006] In the fixing of multiple electromagnetic steel sheets using an adhesive coating, mechanical stress, thermal stress, and interlayer short circuits are less likely to occur during processing. Therefore, the magnetic properties of the electromagnetic steel sheet are less likely to deteriorate, and the performance of the laminated iron core can be fully utilized.

[0007] Based on these advantages, various techniques for fixing multiple laminated steel plates using adhesive methods were studied.

[0008] For example, Patent Document 1 discloses "an electromagnetic steel plate with a surface coating for bonding, characterized in that it is an electromagnetic steel plate having an insulating coating on its surface that exerts its bonding ability by heating and / or pressurizing, wherein the coating is a mixture of epoxy resin or epoxy resin modifier with a glass transition temperature (Tg) of 80°C to 150°C, epoxy resin curing agent, and particulate polymer with a particle size of 0.01μm to 0.5μm."

[0009] In addition, Patent Document 2 discloses "an electromagnetic steel plate laminate, characterized in that it comprises a plurality of electromagnetic steel plates and a welding layer located between the plurality of electromagnetic steel plates, the welding layer comprising a polyethylene acrylate containing repeating units represented by the following chemical formula 1 and repeating units represented by the following chemical formula 2, the polyethylene acrylate containing 65 to 90% by weight of repeating units represented by the following chemical formula 1 and 10 to 35% by weight of repeating units represented by the following chemical formula 2".

[0010] In addition, Patent Document 3 discloses "a laminated electromagnetic steel plate comprising an electromagnetic steel plate and an adhesive insulating film, wherein the adhesive insulating film is disposed on at least one side of the electromagnetic steel plate and has a Marton hardness (HM) of 50 or more and less than 500".

[0011] In addition, Patent Document 4 discloses "an electromagnetic steel strip or electromagnetic steel plate, characterized in that it is an electromagnetic steel strip or electromagnetic steel plate having at least one thermosetting sintered enamel coating on one of its planes, wherein the thermosetting sintered enamel coating comprises an epoxy resin main component, at least one curing agent and at least one filler, wherein the filler of the sintered enamel coating comprises a metal carbonate, a metal sulfate, a metal sulfide, a metal silicate or a metal phosphate, or any mixture thereof."

[0012] In addition, Patent Document 5 discloses "an electromagnetic steel plate with an insulating coating, which is an electromagnetic steel plate having a heat-resistant adhesive insulating coating on one or both sides, wherein the heat-resistant adhesive insulating coating contains 10% by mass or more of a polycarbonate urea resin with a softening point of 20 to 200°C and 10 to 1000 parts by mass of phenolic resin relative to 100 parts by mass of the polycarbonate urea resin".

[0013] Prior art literature

[0014] Patent documents

[0015] Patent Document 1: International Publication No. 2004 / 070080

[0016] Patent Document 2: Japanese Patent Publication No. 2023-508140

[0017] Patent Document 3: International Publication No. 2016 / 017132

[0018] Patent Document 4: Japanese Patent Publication No. 2018-518591

[0019] Patent Document 5: Japanese Patent Application Publication No. 2017-179233 Summary of the Invention

[0020] The technical problem that the invention aims to solve

[0021] However, according to patent documents 1-5, in existing technologies, increasing the adhesive strength of the adhesive coating results in a decrease in the magnetic properties of the electromagnetic steel sheet. Therefore, the adhesive strength of the adhesive coating and the magnetic properties of the electromagnetic steel sheet are contradictory and difficult to balance. In particular, it is necessary to ensure the adhesive strength of the electromagnetic steel sheet with the adhesive coating at both room temperature and high temperature.

[0022] Therefore, it is desirable to further improve the bonding strength and magnetic properties of electromagnetic steel sheets with adhesive coatings at both room temperature and high temperature.

[0023] The subject of this disclosure is to provide an electromagnetic steel sheet with an adhesive coating that has excellent bonding strength and magnetic properties at both room temperature and high temperature, a laminated iron core using the electromagnetic steel sheet, and a method for manufacturing the same.

[0024] Technical means for solving technical problems

[0025] The specific means used to solve technical problems include the following methods.

[0026] [1] An electromagnetic steel plate with an adhesive coating, comprising:

[0027] Electromagnetic steel sheet; and

[0028] An adhesive coating is applied to at least a portion of one or both sides of the electromagnetic steel plate.

[0029] The adhesive coating comprises a crosslinked thermoplastic resin A and a thermoplastic resin B other than the crosslinked thermoplastic resin A.

[0030] The glass transition temperature is 45–80℃, and the melt flow rate at 100℃ is 1.0–25 g / 10 min.

[0031] [2] The electromagnetic steel sheet with adhesive coating as described in [1] above, wherein the crosslinked thermoplastic resin A is one or more of (meth)acrylic resin and polyester resin.

[0032] [3] The electromagnetic steel sheet with adhesive coating as described in [1] above, wherein the mass ratio of the crosslinked thermoplastic resin A to the thermoplastic resin B is 97 / 3 to 70 / 30.

[0033] [4] A stacked iron core, comprising stacked multiple electromagnetic steel plates with adhesive coatings as described in any one of [1] to [3] above, wherein the electromagnetic steel plates are bonded together by the curing film of the adhesive coating.

[0034] [5] A method for manufacturing an electromagnetic steel sheet with an adhesive coating is a method for manufacturing an electromagnetic steel sheet with an adhesive coating as described in any one of [1] to [4] above.

[0035] A coating liquid is applied to at least a portion of one or both sides of an electromagnetic steel sheet to form a coating film. The coating liquid contains particles of the crosslinked thermoplastic resin A and thermoplastic resin B other than the crosslinked thermoplastic resin A. The mass ratio of the crosslinked thermoplastic resin A to the thermoplastic resin B is 60 / 40 to 97 / 3.

[0036] The coated film is dried to form the adhesive coating.

[0037] [6] A method for manufacturing a laminated iron core is the method for manufacturing a laminated iron core as described in [4] above.

[0038] The electromagnetic steel plates with adhesive coatings are sandwiched between each other to form a laminate.

[0039] The laminate is heated and pressurized to cure the adhesive coating, forming the cured film.

[0040] Invention Effects

[0041] According to this disclosure, an electromagnetic steel sheet with an adhesive coating that exhibits excellent bonding strength and magnetic properties at both room temperature and high temperature, a laminated iron core using the electromagnetic steel sheet, and a method for manufacturing the same are provided. Attached Figure Description

[0042] Figure 1 This is a schematic diagram illustrating an example of an electromagnetic steel sheet with an adhesive coating according to the present disclosure.

[0043] Figure 2 This is a schematic diagram illustrating an example of a laminated iron core according to the present disclosure. Detailed Implementation

[0044] The following is an explanation of this disclosure.

[0045] The description of the requirements described below is sometimes based on representative embodiments of this disclosure, but this disclosure is not limited to such embodiments, and appropriate modifications can be made to implement it within the scope of the purpose of this disclosure.

[0046] In this disclosure, the numerical range represented by "~" means that the values ​​recorded before and after "~" are respectively the lower limit and the upper limit.

[0047] Within the numerical ranges described in this disclosure, the upper or lower limit of a certain numerical range can be replaced by the upper or lower limit of other numerical ranges described in different stages. Furthermore, within the numerical ranges described in this disclosure, the upper or lower limit of a certain numerical range can be replaced by the values ​​shown in the embodiments.

[0048] In this disclosure, a combination of two or more preferred methods is a more preferred method.

[0049] In this disclosure, "mass%" and "weight" have the same meaning, and "parts of mass" and "parts of weight" have the same meaning.

[0050] [Electromagnetic steel sheet with adhesive coating]

[0051] The electromagnetic steel plate with adhesive coating disclosed herein has an electromagnetic steel plate and an adhesive coating disposed on at least a portion of one or both sides of the electromagnetic steel plate (see reference). Figure 1 ).

[0052] The adhesive coating comprises a crosslinked thermoplastic resin A and a thermoplastic resin B other than the crosslinked thermoplastic resin A.

[0053] Furthermore, the glass transition temperature of the adhesive coating is 45–80°C, and the melt flow rate at 100°C is 1.0–25 g / 10 min.

[0054] Here, Figure 1 In the diagram, 10 represents an electromagnetic steel sheet with an adhesive coating, 10A represents an electromagnetic steel sheet, and 10B and 10C represent adhesive coatings.

[0055] The electromagnetic steel sheet with adhesive coating disclosed herein exhibits excellent bonding strength and magnetic properties at both room temperature and high temperature due to the aforementioned structure.

[0056] The reasoning is as follows: When fabricating a laminated core by bonding electromagnetic steel sheets with an adhesive coating, stress is imparted to the electromagnetic steel sheets due to the volume shrinkage of the organic resin. This stress deteriorates the iron loss of the electromagnetic steel sheets. However, when driven by a motor installed on the laminated core, the electromagnetic steel sheets heat up, thereby reducing stress and lowering (improving) the iron loss. Therefore, the organic resin, which becomes fluid with increasing temperature, can improve the magnetic properties of the laminated core. However, if the fluidity is too high due to temperature rise, the bond strength at high temperatures decreases. Consequently, the bonding force between the laminated electromagnetic steel sheets decreases, sometimes resulting in vibration or noise. Furthermore, in harsh conditions, there may be misalignment between the steel sheets, leading to contact between the rotor and stator.

[0057] Therefore, by including specific organic resins in the adhesive coating and specifying the melt flow rate at 100°C as a flowability indicator, appropriate flowability can be ensured, while taking into account both magnetic properties and adhesive strength at both room temperature and high temperature.

[0058] The details of the electromagnetic steel sheet with adhesive coating disclosed herein will be described below.

[0059] (Electromagnetic steel sheet)

[0060] Electromagnetic steel sheets are steel sheets formed by bonding and coating, and there are no particular restrictions. Electromagnetic steel sheets can be either non-oriented or oriented.

[0061] Specifically, as an electromagnetic steel sheet, for example, a steel sheet obtained by cutting oriented electromagnetic steel strips of JIS C 2552:2014, oriented electromagnetic steel strips of JIS C 2553:2019, non-oriented thin electromagnetic steel strips of JIS C 2558:2021, or oriented thin electromagnetic steel strips to a predetermined length can be used.

[0062] (Adhesive coating)

[0063] The adhesive coating is applied to at least a portion of one or both sides of the electromagnetic steel plate (refer to...). Figure 1 That is, the adhesive coating can be applied to one or both sides of the electromagnetic steel plate, or it can be applied to one or both sides of the electromagnetic steel plate in a staggered pattern (an alternating arrangement that shifts upwards, downwards, leftwards, and rightwards).

[0064] However, the area of ​​the adhesive coating relative to one side of the electromagnetic steel sheet is preferably set to 60% or more, 80% or more, or 100%.

[0065] [Glass transition temperature]

[0066] The glass transition temperature of the adhesive coating is 45–80℃.

[0067] When the glass transition temperature of the adhesive coating is less than 45°C, the adhesive strength at room temperature and / or high temperature decreases.

[0068] When the glass transition temperature of the adhesive coating exceeds 80°C, the weldability of the organic resin used decreases and its coatability deteriorates. As a result, the adhesive strength at room temperature decreases or the magnetic properties deteriorate.

[0069] Therefore, the glass transition temperature of the adhesive coating is set within the above-mentioned range. The glass transition temperature of the adhesive coating is preferably 50°C or higher. Furthermore, the glass transition temperature of the adhesive coating is preferably 75°C or lower, more preferably 70°C or lower.

[0070] The glass transition temperature of the adhesive coating can be adjusted according to the type and mass ratio of crosslinked thermoplastic resin A and thermoplastic resin B.

[0071] Furthermore, the glass transition temperature of the adhesive coating can be adjusted according to the type and amount of crosslinking agent described later.

[0072] The glass transition temperature of the adhesive coating was determined according to the following method.

[0073] The adhesive coating on the electromagnetic steel sheet being tested is mechanically scraped off using a cutter or similar tool. The moisture from the scraped-off adhesive coating is removed, and the resulting material is granulated to obtain the test sample.

[0074] For the test sample, the glass transition temperature was determined using a differential scanning calorimeter (DSC) according to JIS K 7121:1987, with a test temperature range of -90 to 100 °C, a heating rate of 10 °C / min, and an empty sample pan as the standard substance.

[0075] The glass transition temperature of the adhesive coating is obtained by measuring the temperature of the intersection point of the straight line extending the baseline from the low-temperature side to the high-temperature side in the DSC curve obtained by a differential scanning calorimeter, and the tangent line drawn from the point where the slope of the curve is the largest in the stepwise change of the glass transition.

[0076] [Mel flow rate]

[0077] The melt flow rate of the adhesive coating at 100°C is 1.0–25 g / 10 min.

[0078] When the melt flow rate of the adhesive coating at 100°C is less than 1.0 g / 10 min, the adhesive strength is too high, the adhesive coating becomes too hard, and the magnetic properties deteriorate.

[0079] When the melt flow rate of the adhesive coating at 100°C exceeds 25 g / 10 min, the adhesive strength decreases. Furthermore, the magnetic properties deteriorate.

[0080] Therefore, the melt flow rate of the adhesive coating at 100°C is set within the above-mentioned range. The melt flow rate of the adhesive coating at 100°C is preferably 3.0 g / 10 min or more, more preferably 5.0 g / 10 min or more. Furthermore, the melt flow rate of the adhesive coating at 100°C is preferably 20 g / 10 min or less, more preferably 15 g / 10 min or less.

[0081] The melt flow rate of the adhesive coating at 100°C can be adjusted according to the type and mass ratio of crosslinked thermoplastic resin A and thermoplastic resin B.

[0082] Furthermore, the melt flow rate of the adhesive coating can also be adjusted by the type and amount of crosslinking agent described later.

[0083] The melt flow rate of the adhesive coating at 100°C was determined by the following method.

[0084] The adhesive coating on the electromagnetic steel sheet being tested is mechanically scraped off using a cutter or similar tool. The moisture from the scraped-off adhesive coating is removed, and the resulting material is granulated to obtain the test sample.

[0085] For the test samples, an MFR measuring device was used, according to JIS K 7210-1:2014, under the conditions of a load of 1 kg and a test temperature of 100 °C, to cut samples extruded from a die with a diameter of 1 mm in 10 minutes and measure their weight. Thus, the melt flow rate of the adhesive coating at 100 °C was obtained.

[0086] [Average thickness of adhesive coating]

[0087] The average thickness of the adhesive coating is preferably 1.0 to 6.0 μm. More preferably, the average thickness of the adhesive coating is 1.5 μm or more, or 2.0 μm or more. Furthermore, the average thickness of the adhesive coating is more preferably 4.0 μm or less, or 3.0 μm or less.

[0088] In the electromagnetic steel sheet with adhesive coating disclosed herein, even when the average thickness of the adhesive coating is thin and the film is 1.0 to 6.0 μm, the adhesive strength and magnetic properties at both room temperature and high temperature are excellent.

[0089] The method for determining the average thickness of the adhesive coating is as follows.

[0090] The electromagnetic steel plate with an adhesive coating is cut along the thickness direction to obtain a test piece with the cut surface as the observation surface.

[0091] The thickness of the adhesive coating was measured at three arbitrary locations on the observation surface of the test piece using a scanning electron microscope (SEM). The average thickness of the adhesive coating was obtained by arithmetically averaging the thicknesses at these three locations. Furthermore, the adhesive coating and the electromagnetic steel sheet can be easily distinguished based on differences in brightness; the layer located in the center of the sheet thickness direction is considered the electromagnetic steel sheet, while the layers located on the surface and back side of the sheet thickness direction are considered the adhesive coating.

[0092] [Components of the adhesive coating]

[0093] The adhesive coating comprises crosslinked thermoplastic resin A and thermoplastic resin B other than crosslinked thermoplastic resin A.

[0094] The adhesive coating is a coating that exhibits adhesive properties and insulation, which is cured by heating and pressurizing, at least through the crosslinking progress of crosslinked thermoplastic resin A.

[0095] - Crosslinked thermoplastic resin A -

[0096] Crosslinked thermoplastic resin A is a thermoplastic resin with crosslinking groups.

[0097] The crosslinked thermoplastic resin A is preferably a water-insoluble resin. Here, a water-insoluble resin refers to a resin that is insoluble in water or has low solubility in water. Specifically, a water-insoluble resin is a resin whose solubility in water at 25°C is less than 1g per 100g of water.

[0098] The crosslinked thermoplastic resin A is preferably dispersed in particulate form in an adhesive coating in which thermoplastic resin B is used as the base resin.

[0099] Furthermore, the adhesive coating may contain only one type of crosslinked thermoplastic resin A, or it may contain two or more types.

[0100] In crosslinked thermoplastic resin A, the crosslinking group can be either a crosslinking group that can crosslink even in the absence of a crosslinking agent (i.e., a self-crosslinking group that crosslinks by reacting with each other), or a crosslinking group that can crosslink by reacting with a crosslinking agent.

[0101] Furthermore, the crosslinking group is preferably a group that can exhibit crosslinking properties when heated.

[0102] Specifically, crosslinking groups include: N-hydroxymethyl, N-hydroxybutyl, glycidyl, alkoxymethylamide, alkoxysilyl, hydroxyl, phenolic hydroxyl, carboxyl, thiol, amino, etc.

[0103] The crosslinked thermoplastic resin A can be any of the vinyl-based and non-vinyl-based thermoplastic resins.

[0104] Examples of non-vinyl thermoplastic resins include: polyester resins, polyurethane resins, polyamide resins, phenoxy resins, styrene resins, (meth)acrylic resins, and polyolefin resins.

[0105] Examples of vinyl-based thermoplastic resins include homopolymers of monomers such as styrene-based monomers (e.g., styrene, p-chlorostyrene, α-methylstyrene), (meth)acrylic acid monomers (e.g., (meth)acrylic acid, (meth)acrylic acid alkyl esters), and olefin monomers (e.g., ethylene, propylene, butadiene), or copolymers of two or more of these monomers.

[0106] "Styrene monomers" refers to monomers that have a styrene skeleton (a structure in which one of the six hydrogen atoms in benzene is replaced by a vinyl group).

[0107] "Styrene-based resin" refers to a resin in which the proportion of structural units derived from methylstyrene monomers is more than 50% by mass relative to all structural units.

[0108] "(Meth)acrylic monomers" refers to monomers containing a (meth)acryloyl group.

[0109] "(Meth)acrylic monomers" refers to resins in which structural units derived from (meth)acrylic monomers account for more than 50% by mass of all structural units.

[0110] "(Meth)acrylic acid" is a term that includes both "acrylic acid" and "methacrylic acid".

[0111] "Olefin monomers" refers to monomers that have an olefin skeleton consisting of at least 3 carbon atoms and carbon-carbon double bonds.

[0112] "Olefin monomers" refers to resins in which structural units derived from olefin monomers account for more than 50% by mass of all structural units.

[0113] From the viewpoint of improving adhesive strength and magnetic properties, one or more of (meth)acrylic resins and polyester resins are preferred as crosslinking thermoplastic resin A.

[0114] - Content of cross-linked thermoplastic resin A -

[0115] Compared to adhesive coating, the content of crosslinked thermoplastic resin A is preferably 60% to 95% by mass, more preferably 65% ​​to 90% by mass, and even more preferably 75% to 90% by mass.

[0116] -Thermoplastic Resin B-

[0117] Thermoplastic resin B is a thermoplastic resin other than cross-linked thermoplastic resin A.

[0118] Thermoplastic resin B is preferably a water-soluble resin. Here, water-soluble resin refers to a resin whose solubility in water at 25°C is 5g or more per 100g of water.

[0119] Furthermore, the adhesive coating may contain only one thermoplastic resin B, or it may contain two or more.

[0120] Thermoplastic resin B can be any of vinyl-based thermoplastic resins and non-vinyl-based thermoplastic resins.

[0121] Examples of non-vinyl thermoplastic resins include non-vinyl resins exemplified in cross-linked thermoplastic resin A.

[0122] Examples of vinyl-based thermoplastic resins include vinyl-based resins exemplified in crosslinked thermoplastic resin A.

[0123] From the viewpoint of improving adhesive strength and magnetic properties, at least one of (meth)acrylic resin and polyester resin is preferred as thermoplastic resin B.

[0124] Here, thermoplastic resin B can be either a cross-linked thermoplastic resin or a non-cross-linked thermoplastic resin, but from the viewpoint of improving magnetic properties, a non-cross-linked thermoplastic resin is preferred.

[0125] As a non-crosslinked thermoplastic resin, one can cite resins that do not have crosslinking groups as exemplified in crosslinked thermoplastic resin A.

[0126] - Content of thermoplastic resin B -

[0127] Thermoplastic resin B preferably contains a specified amount relative to crosslinked thermoplastic resin A in the adhesive coating. Specifically, the mass ratio of crosslinked thermoplastic resin A to thermoplastic resin B (content of crosslinked thermoplastic resin A / content of thermoplastic resin B) is preferably 95 / 5 to 85 / 15, more preferably 95 / 5 to 90 / 10.

[0128] If the mass ratio of crosslinked thermoplastic resin A to thermoplastic resin B is 95 / 5 to 85 / 15, the bonding strength and magnetic properties are both superior.

[0129] -Other ingredients-

[0130] Adhesive coatings may also contain other components (so-called other components) as needed, without compromising their effectiveness.

[0131] In particular, the adhesive coating may also contain a crosslinking agent. Crosslinking agents are a particularly preferred component because they have a positive effect on both adhesive strength and magnetic properties.

[0132] Examples of crosslinking agents include thermosetting resins, specifically high molecular weight crosslinking agents such as epoxy resins, phenolic resins, and amino resins (melamine resins, guanidine resins, etc.), as well as low molecular weight crosslinking agents composed of monomers or oligomers such as isocyanate compounds, polyol compounds, epoxy compounds, phenolic compounds, and amino compounds (melamine compounds, guanidine compounds, etc.).

[0133] The content of the crosslinking agent is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, relative to the adhesive coating.

[0134] Adhesive coatings can contain only one crosslinking agent or two or more.

[0135] The composition of the adhesive coating was determined by weight-average molecular weight using GPC, and further determined by functional group analysis using FT-IR.

[0136] The weight-average molecular weight of the adhesive coating components was determined by GPC (Gel Permeation Chromatography). The composition of the adhesive coating was determined based on the molecular weight distribution obtained from GPC.

[0137] The measurement conditions are as follows.

[0138] Measurement apparatus: High-speed GPC (HLC-8220GPC, manufactured by Tosoh Co., Ltd.)

[0139] Detector: Differential Refractive Index Detector (RI) (the device registered as HLC-8220, manufactured by Tosoh Co., Ltd.)

[0140] Pillars: 4 TSK-gel GMHXL (manufactured by Tosoh Co., Ltd.)

[0141] Column temperature: 40℃

[0142] Eluent: Tetrahydrofuran

[0143] Injection volume of sample solution: 100 μL

[0144] Flow rate: 0.8 mL / min

[0145] The functional groups of the adhesive coating components were analyzed using FT-IR (Fourier transform infrared spectrometer). The obtained spectra were converted into a form similar to conventional absorbance spectra using Kramers-Kronig resolution. The functional groups were then identified based on the obtained absorbance spectra.

[0146] The measurement conditions are as follows.

[0147] Measurement device: Spot light 400 (manufactured by Perkin Elmer)

[0148] Measurement method: Orthographic reflection method (background: gold plating)

[0149] Resolution: 2cm －1

[0150] Scans: 16

[0151] As a component of the adhesive coating, for example, in the case of a crosslinked thermoplastic resin A containing a (meth)acrylic resin, the weight-average molecular weight is 80,000 to 300,000, and N-hydroxymethyl, glycidyl, carboxyl or amino groups are detected.

[0152] In the case of crosslinked thermoplastic resin A containing polyester resin, the weight-average molecular weight is 30,000 to 120,000, and hydroxyl or carboxyl groups are detected.

[0153] When using thermoplastic resin B, the weight-average molecular weight is 10,000 to 100,000, and carboxyl or hydroxyl functional groups are detected.

[0154] (Manufacturing method of electromagnetic steel sheet with adhesive coating)

[0155] (Methods for forming adhesive coatings)

[0156] The adhesive coating is formed by applying an adhesive coating forming liquid (hereinafter also referred to as "the coating liquid of the present disclosure") to at least a portion of one or both sides of an electromagnetic steel sheet and allowing the coating film to dry.

[0157] Furthermore, in this disclosure, the amount of each component in the coating liquid for forming an adhesive film is the total amount of the aforementioned multiple substances present in the coating liquid for forming an adhesive film, unless otherwise specified.

[0158] The coating liquid disclosed herein may contain, for example, particles of cross-linked thermoplastic resin A (hereinafter also referred to as "cross-linked thermoplastic resin particles A"), thermoplastic resin B, and a medium containing water.

[0159] In the coating liquid of this disclosure, crosslinked thermoplastic resin particles A exist in a state of dispersion in a medium containing water.

[0160] Furthermore, thermoplastic resin B exists in a state of being dissolved in a medium containing water.

[0161] In the coating solution, the mass ratio of crosslinked thermoplastic resin A to thermoplastic resin B is 60 / 40 to 97 / 3. By using a coating solution containing crosslinked thermoplastic resin A and thermoplastic resin B in this mass ratio, the aforementioned adhesive coating can be formed.

[0162] There is no specific limitation on the type of water used here.

[0163] As for water, distilled water, deionized water (also known as "ion-exchanged water"), and pure water are preferred, for example, from the viewpoint of having fewer impurities.

[0164] The water content is preferably 35% to 50% by mass, more preferably 40% to 45% by mass, relative to the total mass of the coating liquid.

[0165] The coating liquid disclosed herein may, as needed, contain other components (so-called other components) besides those mentioned above, without impairing its effectiveness.

[0166] Other components include, for example, aqueous media other than water.

[0167] As a water-based medium other than water, examples include water-miscible organic solvents.

[0168] Examples of water-miscible organic solvents include: monohydric alcohols such as methanol and ethanol; polyhydric alcohols such as glycerol, ethylene glycol, and propylene glycol; and diol derivatives such as ethylene glycol monoethyl ether and propylene glycol monobutyl ether.

[0169] In addition, other components include various additives such as chain preservatives, wetting agents, and defoamers.

[0170] The coating liquid disclosed herein is obtained, for example, by mixing a dispersion formed by dispersing crosslinked thermoplastic resin particles A in water with an aqueous solution of thermoplastic resin B.

[0171] As a mixing method, one example is mixing by stirring.

[0172] Stirring can be done using general stirring utensils or stirring devices.

[0173] There is no particular limitation on the stirring temperature, but it is preferably 20°C to 30°C.

[0174] The formation of an adhesive film using the coating liquid disclosed herein can be achieved by the following methods: applying the coating liquid to the surface of an electromagnetic steel sheet using a known coating method such as a roller coater or a spray coater, and then drying the coating film.

[0175] The concentration of solid components in the coating liquid is preferably 5 to 40% by mass, more preferably 10 to 25%.

[0176] The preferred drying temperature is 100–200℃, and the preferred drying time is 10–90 seconds.

[0177] The drying method is preferably a heating furnace similar to a photocopying furnace, but it can also be a hot air furnace or other methods.

[0178] (Layered iron core)

[0179] The present invention discloses a laminated iron core having multiple electromagnetic steel plates with adhesive coatings laminated thereon, wherein the electromagnetic steel plates are bonded together by the curing film of the adhesive coating.

[0180] Here, the cured film of the adhesive coating refers to the film that exhibits adhesive ability, formed by heating and pressurizing the laminated electromagnetic steel plates with adhesive coatings, which cures the cross-linking of the cross-linked thermoplastic resin A in the adhesive coating.

[0181] Whether the adhesive coating has cured can be determined using the following methods.

[0182] Two 30mm × 60mm single-layer test pieces were cut from an electromagnetic steel sheet with an adhesive coating. The 30mm × 10mm ends of the two single-layer test pieces were overlapped with their adhesive coatings facing each other. The laminate was heated and pressurized at a steel plate temperature of 250℃, a pressure of 2MPa, and a heating and pressurization time of 1 minute to obtain a sample for adhesive strength testing.

[0183] The tensile shear bond strength was determined at room temperature (25℃) on the steel plate. The sample for bond strength determination was mounted on a tensile testing machine, and the tensile shear bond strength was determined at a tensile speed of 50 mm / min.

[0184] The value obtained by dividing the tensile shear bond strength by the bond area of ​​the two veneer test pieces is taken as the room temperature bond strength.

[0185] If the bonding strength at room temperature is above 5.0 MPa, it can be determined that the bonding strength is sufficient at room temperature, and the adhesive coating has been cured.

[0186] Specifically, as a laminated iron core of this disclosure, for example, a laminated iron core is formed by punching out an electromagnetic steel plate with an adhesive coating to make a punching component, stacking the punching component, heating and pressurizing it to form an integral laminated iron core.

[0187] Figure 2 This is a schematic diagram illustrating an example of a laminated iron core according to the present disclosure. For example... Figure 2 As shown, the laminated iron core 100 (stator 100) is formed by connecting eight stamping members 11 with adhesive coatings on the electromagnetic steel plates into a ring shape, and stacking the stamping members 11 connected into a ring shape into eight layers to form a laminated body 13.

[0188] The punching member 11 for the electromagnetic steel sheet with adhesive coating punches the electromagnetic steel sheet with adhesive coating and has an arc-shaped yoke 17 and a toothed part 15 that protrudes radially inward from the inner circumference of the yoke 17.

[0189] Furthermore, the laminated iron core 100 is not limited to Figure 2 The shape, number, and number of layers of the punching members 11 that form the stacked iron core 100 can be designed according to the purpose.

[0190] (Manufacturing method of laminated iron core)

[0191] The laminated iron core disclosed herein is manufactured, for example, by the following method.

[0192] First, the electromagnetic steel plates with adhesive coatings disclosed herein are stacked in such a way that the adhesive coatings are spaced apart between each other.

[0193] The laminate of electromagnetic steel sheets with adhesive coating is heated and pressurized, causing the cross-linking of the cross-linked thermoplastic resin A in the adhesive coating to proceed, thus curing the adhesive coating. The cured adhesive coating then exerts its adhesive properties, bonding the electromagnetic steel sheets together.

[0194] Through these operations, the stacked iron core of this disclosure is obtained.

[0195] In addition, the electromagnetic steel sheets with adhesive coatings can be bonded to each other by the cured films of the adhesive coatings of the electromagnetic steel sheets facing each other, or the cured film of the adhesive coating of one electromagnetic steel sheet can be bonded to the side of another electromagnetic steel sheet that does not have an adhesive coating.

[0196] The preferred heating temperature is 200–300℃, the preferred pressure is 0.5–10 MPa, and the preferred heating and pressurizing time is 30–60 minutes.

[0197] (Applications of laminated iron cores)

[0198] The laminated iron core disclosed herein can be used as an iron core (i.e., iron core) for use in rotating motors and the like.

[0199] Example

[0200] The coating liquid of this disclosure will be described in more detail below through examples. This disclosure is not limited to the following examples without departing from its spirit.

[0201] [Examples 1-8, Comparative Examples 1-11]

[0202] 1. Manufacturing of coating liquid

[0203] A coating solution with a solid content of 40% by mass is prepared by mixing an aqueous dispersion of crosslinked thermoplastic resin particles A, an aqueous solution of thermoplastic resin B, and a crosslinking agent, according to the types and amounts (parts by mass) shown in Tables 1A and 1B.

[0204] The amounts (parts by mass) of crosslinked thermoplastic resin particles A, thermoplastic resin B, and crosslinking agent in the coating liquid are shown in Tables 1A and 1B. Empty columns in the tables indicate materials not conforming to that column were not used. Furthermore, underlines in the tables indicate items outside the scope of this disclosure.

[0205] In addition, the so-called "solid component concentration" refers to the total mass ratio of the aqueous solution of crosslinked thermoplastic resin particles A and thermoplastic resin B, and the crosslinking agent to the coating liquid.

[0206] Furthermore, in Examples 1-4, 8, and Comparative Examples 3-4, 7-10, coating solutions that do not contain crosslinking agents were obtained.

[0207] In Comparative Example 1, a coating liquid that did not contain thermoplastic resin B and crosslinking agent was obtained.

[0208] In Comparative Example 5, a coating liquid that did not contain crosslinked thermoplastic resin particles A and a crosslinking agent was obtained.

[0209] In Comparative Example 6, a coating liquid that did not contain thermoplastic resin B was obtained.

[0210] In Comparative Example 11, a coating liquid that did not contain cross-linked thermoplastic resin particles A was obtained.

[0211] 2. Fabrication of electromagnetic steel sheets with adhesive coating

[0212] First, non-oriented electromagnetic steel sheets were prepared: by mass percentage, Si: 3.0%, Mn: 0.2%, Al: 0.5%, with the remainder consisting of Fe and impurities, thickness: 0.25mm, width: 100mm.

[0213] Next, the obtained coating liquid is applied to the entire single side of the electromagnetic steel plate, and then heated at the drying temperature and drying time shown in Table 1A and Table 1B to dry the coating film, forming an adhesive film with an average thickness shown in Table 1A and Table 1B.

[0214] In this way, an electromagnetic steel sheet with an adhesive coating was obtained.

[0215] [evaluate]

[0216] (Glass transition temperature, melt flow rate)

[0217] The glass transition temperature (Tg) and melt flow rate (MFR) of the adhesive coating in the electromagnetic steel sheet with adhesive coating in each example were determined according to the methods described above.

[0218] (Adhesive strength)

[0219] Two 30mm × 60mm single-layer test pieces were cut from the electromagnet steel sheets with adhesive coatings in each example. The 30mm × 10mm ends of the two single-layer test pieces were overlapped with their adhesive coatings facing each other. The laminate was heated and pressurized under the conditions of steel sheet temperature: 250℃, pressure: 2MPa, and heating and pressurizing time: 1 minute to obtain samples for adhesive strength testing.

[0220] The tensile shear bond strength was determined as follows, with the steel plate at room temperature (25℃). The sample for bond strength determination was mounted on a tensile testing machine, and the tensile shear bond strength was measured at a tensile speed of 50 mm / min.

[0221] Then, the value obtained by dividing the tensile shear bond strength by the bond area of ​​the two veneer test pieces is taken as the room temperature bond strength.

[0222] In addition, a sample for measuring the bonding strength is set in an atmosphere of 150°C. In a state where the steel plate temperature is 150°C, the tensile shear bonding strength is measured by the same method as described above.

[0223] The value obtained by dividing the value of the tensile shear bonding strength thus obtained by the bonding area of two single-plate test pieces is taken as the bonding strength at 150°C.

[0224] When the room temperature bonding strength exceeds 5.0 MPa and the bonding strength at 150°C exceeds 0.5 MPa, it is judged that the bonding strengths at room temperature and high temperature are excellent and judged as qualified. On the other hand, when either one is not satisfied, it is judged that the bonding strengths at room temperature and high temperature are deteriorated and judged as unqualified.

[0225] (Magnetic properties)

[0226] Single-plate test pieces with a size of 55 mm × 55 mm are cut out from the electromagnetic steel plates with bonding films of each example. Then, two single-plate test pieces are overlapped with their bonding films facing each other. The overlapped body is heated and pressed under the conditions of a steel plate temperature of 250°C, a pressing force of 2 MPa, and a heating and pressing time of 1 minute to obtain a laminated body sample.

[0227] The iron losses in the rolling direction and the direction perpendicular to the rolling direction of the obtained laminated body sample are measured by the single-plate magnetic measurement method specified in JIS 2556: 2C15, and the average value of the iron losses in the rolling direction and the direction perpendicular to the rolling direction is obtained.

[0228] When the average value of the obtained iron losses is 11.0 W / kg or less, it is judged that the magnetic properties are excellent and judged as qualified. On the other hand, when the average value of the obtained iron losses exceeds 11.0 W / kg, it is judged that the iron losses are not excellent and judged as unqualified.

[0229] (Appearance)

[0230] Three test pieces with a side length of 5 mm are cut out from the electromagnetic steel plates with bonding films of each example to obtain test pieces.

[0231] Three places on the surface of the bonding film of each test piece are observed with a scanning electron microscope at a magnification of 100 times. The total number of observation fields is nine fields. <000047�>Then, the evaluation is carried out according to the following evaluation criteria, and S and A are regarded as qualified.

[0233] S: No film defects such as cracks, fissures, or peeling are found at all.

[0234] A: The area ratio of the film defects is 10% or less.

[0235] B: The area ratio of coating defects exceeds 10% but is less than 30%.

[0236] C: The area ratio of coating defects is over 30%.

[0237] The detailed information on the materials used, as recorded in Table 1, is shown below.

[0238] <Cross-linked thermoplastic resin A>

[0239] Crosslinked acrylic resin (1): Crosslinking group = N-hydroxymethyl, Tg = 70℃, weight-average molecular weight = 200,000

[0240] Crosslinked acrylic resin (2): Crosslinking group = glycidyl group, Tg = 50℃, weight-average molecular weight = 150,000

[0241] Crosslinked acrylic resin (3): Crosslinking group = carboxyl group, Tg = 55℃, weight-average molecular weight = 120,000

[0242] Crosslinked acrylic resin (4): Crosslinking group = amino, Tg = 85℃, weight-average molecular weight = 80,000

[0243] Crosslinked polyester resin (5): Crosslinking group = hydroxyl, Tg = 60℃, weight-average molecular weight = 50,000

[0244] Crosslinked polyester resin (6): Crosslinking group = carboxyl group, Tg = 85℃, weight-average molecular weight = 30,000

[0245] Crosslinked acrylic resin (7): Crosslinking group = glycidyl group, Tg = 30℃, weight-average molecular weight = 300,000

[0246] Crosslinked polyester resin (8): Crosslinking group = carboxyl group, Tg = 100℃, weight-average molecular weight = 20,000

[0247] <Thermoplastic Resin B>

[0248] Acrylic resin (1): Tg = 60℃, weight-average molecular weight = 180,000

[0249] Acrylic resin (2): Tg = 0℃, weight-average molecular weight = 250,000

[0250] Polyester resin: Tg = 70℃, weight-average molecular weight = 80,000

[0251] Polyurethane resin: Tg = 75℃, weight-average molecular weight = 20,000

[0252] Phenoxy resin (1): Tg = 80℃, weight-average molecular weight = 400,000

[0253] Phenoxy resin (2): Tg = 10℃, weight-average molecular weight = 280,000

[0254] <Cross-linking agent>

[0255] Epoxy resin: Bisphenol A type, weight average molecular weight = 1000-4000

[0256] Phenolic resin: Phenolic varnish type, weight average molecular weight = 3000-5000

[0257] Amino resin: methylated benzoguanidine, weight average molecular weight = 5000–8000

[0258] [Table 1A]

[0259]

[0260] [Table 1B]

[0261]

[0262] [Table 2]

[0263]

[0264] Based on the above results, it can be seen that in this embodiment, compared with the comparative example, the bonding strength and magnetic properties at both room temperature and high temperature are excellent.

[0265] Industrial availability

[0266] According to this disclosure, an electromagnetic steel sheet with an adhesive coating that exhibits excellent bonding strength and magnetic properties at both room temperature and high temperature, a laminated iron core using the electromagnetic steel sheet, and a method for manufacturing the same are provided.

[0267] Explanation of reference numerals in the attached figures

[0268] 10 Electromagnetic steel sheet with adhesive coating

[0269] 10A Electromagnetic Steel Sheet

[0270] 10B Adhesive Coating

[0271] 10C Adhesive Coating

[0272] 11. Punching parts for electromagnetic steel sheets with adhesive coating

[0273] 100-layer laminated iron core

Claims

1. An electromagnetic steel plate with an adhesive coating, comprising: Electromagnetic steel sheet; and An adhesive coating is applied to at least a portion of one or both sides of the electromagnetic steel plate. The adhesive coating comprises a crosslinked thermoplastic resin A and a thermoplastic resin B other than the crosslinked thermoplastic resin A. The glass transition temperature is 45–80℃, and the melt flow rate at 100℃ is 1.0–25 g / 10 min.

2. The electromagnetic steel plate with adhesive coating as described in claim 1, The crosslinked thermoplastic resin A is one or more of (meth)acrylic resins and polyester resins.

3. The electromagnetic steel plate with adhesive coating as described in claim 1, The mass ratio of the crosslinked thermoplastic resin A to the thermoplastic resin B is 97 / 3 to 70 / 30.

4. A layered iron core, Multiple electromagnetic steel plates with adhesive coatings as described in any one of claims 1 to 3 are stacked together, and the electromagnetic steel plates are bonded to each other by the cured film of the adhesive coating.

5. A method for manufacturing an electromagnetic steel sheet with an adhesive coating, as described in any one of claims 1 to 4. A coating liquid is applied to at least a portion of one or both sides of an electromagnetic steel sheet to form a coating film. The coating liquid contains particles of the crosslinked thermoplastic resin A and thermoplastic resin B other than the crosslinked thermoplastic resin A. The mass ratio of the crosslinked thermoplastic resin A to the thermoplastic resin B is 60 / 40 to 97 / 3. The coated film is dried to form the adhesive coating.

6. A method for manufacturing a laminated iron core, as described in claim 4. The electromagnetic steel plates with adhesive coatings are stacked between each other, thereby forming a laminate. The laminate is heated and pressurized to cure the adhesive coating and form the cured film.

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