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. The adhesive film contains (meth) acrylic resin particles A and a water-soluble (meth) acrylic resin B. The (meth) acrylic resin particles A contain structural units derived from a monomer having a self-crosslinkable group, and the weight-average molecular weight of the adhesive film is 150,000-250,000.

Description

Technical Field

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

[0002] This application claims priority based on Japanese Patent Application No. 2023-163616, 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 curable enamel coating on one of its planes, wherein the thermosetting curable enamel coating comprises an epoxy resin main component, at least one curing agent and at least one filler, wherein the filler of the curing 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 polycarbonate polyurethane 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 polyurethane 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 the existing technology, increasing the adhesive strength of the adhesive coating results in a decrease in the magnetic properties of the electromagnetic steel sheet. That is, 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 required 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 technical means used to solve technical problems include the following methods.

[0026] <1> One aspect of this disclosure is an electromagnetic steel plate with an adhesive coating, comprising an electromagnetic steel plate and an adhesive coating disposed on at least a portion of one or both sides of the electromagnetic steel plate.

[0027] The adhesive coating comprises (meth)acrylic resin particles A and water-soluble (meth)acrylic resin B, wherein the (meth)acrylic resin particles A contain structural units derived from monomers having self-crosslinking groups.

[0028] The weight-average molecular weight of the adhesive coating is 150,000 to 250,000.

[0029] <2> In the above <1> In an electromagnetic steel plate with an adhesive coating, the weight-average molecular weight of the soluble components of the adhesive coating after heating it at 200°C for 5 minutes can also be 50,000 to 100,000.

[0030] <3> In the above <1> or <2> In the electromagnetic steel sheet with an adhesive coating, the water-soluble (meth)acrylic resin B can be a (meth)acrylic resin containing structural units derived from monomers with self-crosslinking groups.

[0031] <4> In the above <1> ~ <3> In any of the electromagnetic steel plates with adhesive coatings, the mass ratio of the (meth)acrylic resin particles A to the mass ratio of the water-soluble (meth)acrylic resin B can be 95 / 5 to 85 / 15.

[0032] <5> In the above <1> ~ <4> In any one of the electromagnetic steel plates with an adhesive coating, the self-crosslinking groups of the (meth)acrylic resin particles A may also be at least one selected from the group consisting of N-hydroxymethyl, N-hydroxybutyl and glycidyl groups.

[0033] <6> One embodiment of this disclosure is a stacked iron core, comprising multiple layers as described above. <1> ~ <5> The electromagnetic steel sheet with adhesive coating as described in any one of the claims, wherein the electromagnetic steel sheets are bonded together by the curing film of the adhesive coating.

[0034] <7> The above <6> The stacking factor of the laminated iron core can also be 96~98%.

[0035] <8> One method of manufacturing an electromagnetic steel sheet with an adhesive coating disclosed herein is as described above. <1> A method for manufacturing an electromagnetic steel sheet with an adhesive coating, comprising:

[0036] A coating process involves applying an adhesive coating liquid to at least a portion of one or both sides of an electromagnetic steel sheet to obtain a coated steel sheet. The adhesive coating liquid comprises (meth)acrylic resin particles A and a water-soluble (meth)acrylic resin B. The (meth)acrylic resin particles A contain structural units derived from monomers having self-crosslinking groups.

[0037] The coating process involves heating the coated steel sheet to a drying temperature of 100-200°C at a heating rate of less than 6.0°C / second, and then drying it in a temperature range from the drying temperature to -10°C for 10-90 seconds to form an adhesive coating on the surface of the electromagnetic steel sheet.

[0038] <9> In the above <8> In the method for manufacturing an electromagnetic steel sheet with an adhesive coating, the mass ratio of the (meth)acrylic resin particles A in the coating liquid for forming the adhesive coating to the mass ratio of the water-soluble (meth)acrylic resin B can also be 95 / 5 to 85 / 15.

[0039] <10> One method for manufacturing a laminated iron core disclosed herein is as described above. <6> The manufacturing method of the laminated iron core has the following characteristics:

[0040] The blanking process involves blanking the electromagnetic steel sheet with the adhesive coating to obtain a blanked component;

[0041] The lamination process involves stacking multiple sheets of the punched components to obtain a laminated body; and

[0042] In the bonding process, the laminate is heated to a pressure temperature in the range of 200~300℃, and held at a pressure of 0.5~10MPa for 30~60 minutes within the range of the pressure temperature to the pressure temperature -10℃, thereby curing the adhesive coating to form the cured film.

[0043] Invention Effects

[0044] According to the above-described manner of 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

[0045] Figure 1 This is a schematic diagram illustrating an example of an electromagnetic steel sheet with an adhesive coating according to the present disclosure.

[0046] Figure 2 This is a schematic diagram illustrating an example of a laminated iron core according to the present disclosure. Detailed Implementation

[0047] The following is an explanation of this disclosure.

[0048] 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.

[0049] 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.

[0050] Within the numerical ranges described in this disclosure, the upper or lower limit value recorded within a certain numerical range can be replaced by the upper or lower limit value of other numerical ranges described in different stages. Furthermore, within the numerical ranges described in this disclosure, the upper or lower limit value recorded within a certain numerical range can also be replaced by the value shown in the embodiments.

[0051] In this disclosure, a combination of two or more preferred methods is a more preferred method.

[0052] In this disclosure, the amount of each component in the coating composition for laminated steel sheets is the sum of the amounts of the multiple substances present in the coating composition for laminated steel sheets unless otherwise specified.

[0053] In this disclosure, "(meth)acrylic monomer" refers to a monomer having a (meth)acryloyl group.

[0054] In this disclosure, "(meth)acrylic resin" refers to a resin containing structural units derived from (meth)acrylic monomers, wherein the proportion of structural units derived from (meth)acrylic monomers is 50% or more by mass.

[0055] In this disclosure, "(meth)acrylic acid" is a term that includes both "acrylic acid" and "methacrylic acid", "(meth)acrylate" is a term that includes both "acrylate" and "methacrylate", "(meth)acryloyl" is a term that includes both "acryloyl" and "methacryloyl", and "(meth)acrylamide" is a term that includes both "acrylamide" and "methacrylamide".

[0056] In this disclosure, “n-” means positive, “i-” means different, “s-” means second, and “t-” means uncle.

[0057] In this disclosure, "mass%" and "weight" have the same meaning, and "parts of mass" and "parts of weight" have the same meaning.

[0058] In this disclosure, the term "process" is not only used for independent processes, but also for processes that cannot be clearly distinguished from other processes, as long as the desired goal of the process is achieved.

[0059] [Electromagnetic steel sheet with adhesive coating]

[0060] 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 ).

[0061] The adhesive coating comprises (meth)acrylic resin particles A and water-soluble (meth)acrylic resin B, wherein (meth)acrylic resin particles A contain structural units derived from monomers having self-crosslinking groups.

[0062] Furthermore, the weight-average molecular weight of the adhesive coating is 150,000 to 250,000, and the weight-average molecular weight of the soluble components of the adhesive coating after heating it at 200°C for 5 minutes is 50,000 to 100,000.

[0063] 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.

[0064] The electromagnetic steel sheet with adhesive coating disclosed herein exhibits excellent appearance, bonding strength at both room temperature and high temperature, and magnetic properties based on the aforementioned structure (its magnetic properties as a laminated iron core are also excellent). Furthermore, in this disclosure, "room temperature" refers to 25°C, and "high temperature" refers to 150°C.

[0065] The rationale is speculated as follows: By applying (meth)acrylic resin particles A with self-crosslinking groups to improve the rigidity of the molecular chain, excellent adhesive strength is achieved from room temperature to high temperature. Furthermore, by applying water-soluble (meth)acrylic resin B within the aforementioned molecular weight range to alleviate compressive stress, excellent magnetic properties are obtained.

[0066] The following is a detailed description of the electromagnetic steel sheet with adhesive coating disclosed herein.

[0067] (Electromagnetic steel sheet)

[0068] Electromagnetic steel sheets are steel sheets that are bonded and coated with a film, and there are no particular restrictions.

[0069] Electromagnetic steel sheets can be either non-oriented or oriented.

[0070] Specifically, as an electromagnetic steel sheet, for example, an electromagnetic steel sheet can be made by cutting a non-oriented electromagnetic steel strip of JIS C 2552:2014, an oriented electromagnetic steel strip of JIS C 2553:2019, a non-oriented thin electromagnetic steel strip of JIS C 2558:2021, or an oriented thin electromagnetic steel strip into a specified length.

[0071] (Adhesive coating)

[0072] 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 (alternating staggered arrangement in the up, down, left and right directions).

[0073] Among them, the area of ​​the adhesive coating relative to one side of the electromagnetic steel plate is preferably set to more than 60%, more than 80%, or 100%.

[0074] [Weight-average molecular weight of adhesive coatings and their soluble components]

[0075] The weight-average molecular weight of the adhesive coating is 150,000 to 250,000.

[0076] If the weight-average molecular weight of the adhesive coating is less than 150,000, the adhesive strength cannot be adequately guaranteed. Furthermore, the appearance will deteriorate.

[0077] If the weight-average molecular weight of the adhesive coating exceeds 250,000, the adhesive coating becomes too rigid and its magnetic properties deteriorate.

[0078] Therefore, the weight-average molecular weight of the adhesive coating is set within the above-mentioned range. The weight-average molecular weight of the adhesive coating is preferably 170,000 or more, more preferably 180,000 or more. Furthermore, the weight-average molecular weight of the adhesive coating is preferably 230,000 or less, more preferably 220,000 or less.

[0079] The weight-average molecular weight of the adhesive coating can be set to a desired value by adjusting the polymerization temperature, polymerization time, type and amount of polymerization initiator, and type and amount of chain transfer agent during the manufacturing of each resin.

[0080] Here, "weight-average molecular weight of the adhesive coating" refers to the weight-average molecular weight of the adhesive coating in its untreated state (without heating or other treatments). Furthermore, hereinafter, the weight-average molecular weight of the adhesive coating will also be referred to as "weight-average molecular weight of the adhesive coating before heating".

[0081] The weight-average molecular weight of the soluble components of the adhesive coating after heating at 200°C for 5 minutes (hereinafter also referred to as "weight-average molecular weight of the soluble components of the heated adhesive coating") is 50,000 to 100,000.

[0082] If the weight-average molecular weight of the soluble components in the adhesive coating is above 100,000 after heating, the adhesive strength cannot be adequately guaranteed. In particular, if the adhesive coating is soft, the adhesive strength deteriorates at high temperatures.

[0083] If the weight-average molecular weight of the soluble components of the adhesive coating is less than 50,000 after heating, gelation will progress and the adhesive coating will become too hard, resulting in deterioration of magnetic properties.

[0084] Therefore, the weight-average molecular weight of the soluble components in the heated adhesive coating is set within the above-mentioned range. Preferably, the weight-average molecular weight of the soluble components in the heated adhesive coating is 60,000 or more, more preferably 70,000 or more. Preferably, the weight-average molecular weight of the soluble components in the heated adhesive coating is 90,000 or less.

[0085] The weight-average molecular weight of the soluble components in the heated adhesive coating can be set to a desired value by adjusting the polymerization temperature, polymerization time, type and amount of polymerization initiator, and type and amount of chain transfer agent during the manufacturing of each resin.

[0086] The weight-average molecular weight (Mw) of the adhesive coating before heating and the weight-average molecular weight (Mw) of the soluble components of the adhesive coating after heating were determined as follows.

[0087] First, solution A for Mw determination with adhesive coating before heating is obtained as described below. Adhesive-coated sheets are collected from the electromagnetic steel plate with adhesive coating of the test object.

[0088] On the other hand, as described below, a solution B for determining the soluble components of the heated adhesive coating was obtained. The electromagnetic steel plate with the adhesive coating was heated to a surface temperature of 200°C, and then heated for five minutes after reaching 200°C. Afterwards, it was cooled to room temperature (25°C). An adhesive coating sheet was collected from the heated electromagnetic steel plate with the adhesive coating.

[0089] The weight-average molecular weight was determined using solution A for determining the Mw of the film bonded before heating and solution B for determining the Mw of the soluble components of the film bonded after heating, according to the following (1)~(2).

[0090] (1) Using the adhesive film and tetrahydrofuran obtained above, a sample solution with a solid content concentration of 0.2% by mass was obtained. Here, "solid content concentration" refers to the mass ratio of the resin or soluble component in the sample solution.

[0091] (2) Using gel permeation chromatography (GPC), under the following conditions, the weight-average molecular weight of the soluble components of the adhesive coating before heating and the adhesive coating after heating were determined as the standard polystyrene conversion value.

[0092] ~Conditions~

[0093] Measurement apparatus: High-speed GPC [Model: HLC-8220 GPC, manufactured by Tosoh Corporation]

[0094] Detector: Differential refractometer (RI) [Assembled in HLC-8220, manufactured by Tosoh Corporation]

[0095] Columns: Use 4 TSKgel GMH XL [Tosoh Corporation]

[0096] Column temperature: 40℃

[0097] Eluent: Tetrahydrofuran

[0098] Injection volume of sample solution: 100 μL

[0099] Flow rate: 0.8 mL / min

[0100] (Average thickness of adhesive coating)

[0101] 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.

[0102] In the electromagnetic steel sheet with adhesive coating disclosed herein, even when the average thickness of the adhesive coating is 1.0 to 6.0 μm, the adhesive strength and magnetic properties at both room temperature and high temperature are excellent.

[0103] The method for determining the average thickness of the adhesive coating is as follows.

[0104] The electromagnetic steel plate with adhesive coating is cut along its thickness to obtain a test piece with the cut surface as the observation surface.

[0105] The test specimen was observed using a scanning electron microscope (SEM), and the thickness of the adhesive coating was measured at three arbitrary locations. The thicknesses at these three locations were then arithmetically averaged to determine the average thickness of the adhesive coating. Furthermore, the adhesive coating and the electromagnet steel sheet could be easily distinguished based on differences in brightness when observing the reflected electron images. The layer located in the center of the sheet along its thickness direction was considered the electromagnet steel sheet, while the layers located on the surface and back sides along the sheet thickness direction were considered the adhesive coating.

[0106] (Components of the adhesive coating)

[0107] The adhesive coating comprises (meth)acrylic resin particles A (hereinafter also referred to as "specific (meth)acrylic resin particles A") containing structural units derived from monomers having self-crosslinking groups and water-soluble (meth)acrylic resin B.

[0108] The adhesive coating is cured by heating and pressurizing, at least by the crosslinking progress of specific (meth)acrylic resin particles A, thereby exhibiting an insulating coating with adhesive properties.

[0109] [Specific (meth)acrylic resin particles A]

[0110] The specific (meth)acrylic resin particle A contains structural units derived from monomers having self-crosslinking groups. Specifically, the specific (meth)acrylic resin particle A contains structural units derived from monomers having carboxyl groups and structural units derived from monomers having self-crosslinking groups.

[0111] The adhesive coating may contain only one specific (meth)acrylic resin particle A, or it may contain two or more.

[0112] <Structural units derived from monomers containing carboxyl groups>

[0113] The specific (meth)acrylic resin particles A preferably contain structural units derived from monomers having carboxyl groups in a proportion of 1% by mass or more and less than 20% by mass relative to all structural units.

[0114] In this disclosure, "structural unit from a monomer having a carboxyl group" refers to a structural unit formed by the addition polymerization of a monomer having a carboxyl group.

[0115] As a monomer having a carboxyl group, for example, a monomer having at least one carboxyl group and one olefinic unsaturated group in a molecule can be cited.

[0116] As an olefinic unsaturated group, there are no particular limitations; examples include vinyl, allyl, vinylphenyl, (meth)acrylamido, and (meth)acryloyl.

[0117] As an olefinic unsaturated group, (meth)acryloyl is preferred.

[0118] Specific examples of monomers having a carboxyl group include: (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, pentenediaic acid, citraconic acid, ω-carboxyl-polycaprolactone mono(meth)acrylate [e.g., ω-carboxyl-polycaprolactone (n≒2) monoacrylate] and succinic acid derivatives (e.g., 2-acryloyloxyethyl-succinic acid).

[0119] As a monomer having a carboxyl group, a (meth)acrylic acid monomer having a carboxyl group is preferred, (meth)acrylic acid is more preferred, and methacrylic acid is even more preferred.

[0120] The specific (meth)acrylic resin particles A may contain only one structural unit from a monomer with a carboxyl group, or they may contain two or more structural units.

[0121] The content of structural units derived from carboxyl-containing monomers in specific (meth)acrylic resin particles A is preferably 1% by mass or more and less than 20% by mass relative to all structural units of specific (meth)acrylic resin particles A.

[0122] If the content of structural units derived from carboxyl-containing monomers in a specific (meth)acrylic resin particle A is 1% by mass or more relative to all structural units of the specific (meth)acrylic resin particle A, it tends to have excellent appearance, adhesive strength, and magnetic properties. From this viewpoint, the content of structural units derived from carboxyl-containing monomers in the specific (meth)acrylic resin particle A relative to all structural units of the specific (meth)acrylic resin particle A is preferably 3% by mass or more, more preferably 5% by mass or more, further preferably 8% by mass or more, and particularly preferably 10% by mass or more.

[0123] <Structural units derived from monomers with self-crosslinking groups>

[0124] The specific (meth)acrylic resin particles A preferably contain structural units derived from monomers having self-crosslinking groups in a proportion of 0.1% to 7% by mass relative to all structural units.

[0125] In this disclosure, "structural unit from a monomer having a self-crosslinking group" refers to a structural unit formed by the addition polymerization of a monomer having a self-crosslinking group.

[0126] In this disclosure, "self-crosslinking" refers to the property of being able to crosslink even in the absence of a crosslinking agent.

[0127] The self-crosslinking groups in this disclosure can exhibit self-crosslinking properties upon heating.

[0128] The temperature at which self-crosslinking groups exhibit self-crosslinking properties varies depending on the type of self-crosslinking group.

[0129] Self-crosslinking groups only need to exhibit self-crosslinking properties at the temperature at which the electromagnetic steel sheets are bonded together; there is no particular limitation on the temperature at which self-crosslinking groups exhibit self-crosslinking properties.

[0130] Specific examples of self-crosslinking groups include N-hydroxymethyl, N-hydroxybutyl, glycidyl, and alkoxymethylamide.

[0131] As a self-crosslinking group, it is preferably at least one selected from the group consisting of N-hydroxymethyl, N-hydroxybutyl, and glycidyl groups.

[0132] Specific examples of monomers having self-crosslinking groups include N-hydroxyalkyl (meth)acrylamide, N,N-dihydroxyalkyl (meth)acrylamide, glycidyl (meth)acrylate, and N-alkoxymethyl (meth)acrylamide.

[0133] Examples of N-hydroxyalkyl (meth)acrylamides include N-hydroxymethylacrylamide (NMAM), N-hydroxybutylacrylamide (NBMA), and hydroxyethylacrylamide (HEAA).

[0134] Examples of N,N-dihydroxyalkyl (meth)acrylamides include, for instance, dihydroxymethyl (meth)acrylamide.

[0135] Examples of N-alkoxymethyl (meth)acrylamides include N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, and N-butoxymethyl (meth)acrylamide.

[0136] As a monomer having a self-crosslinking group, it is preferably at least one selected from the group consisting of N-hydroxymethylacrylamide (NMAM), N-hydroxybutylacrylamide (NBMA), and hydroxyethylacrylamide (HEAA), more preferably hydroxyethylacrylamide (HEAA).

[0137] The specific (meth)acrylic resin particles A may contain only one structural unit from a monomer with a self-crosslinking group, or they may contain two or more structural units.

[0138] The content of structural units derived from monomers having self-crosslinking groups in specific (meth)acrylic resin particles A is preferably 0.1% by mass or more and 7% by mass or less relative to all structural units of specific (meth)acrylic resin particles A.

[0139] The content of structural units derived from monomers with self-crosslinking groups in specific (meth)acrylic resin particles A can be in a range of 0.1% to 6% by mass, 0.1% to 5% by mass, 1% to 7% by mass, 1.5% to 6% by mass, or 1.9% to 5% by mass in a certain manner.

[0140] <Structural units derived from (meth)acrylate alkyl ester monomers>

[0141] The specific (meth)acrylic resin particles A preferably contain structural units derived from (meth)acrylic alkyl ester monomers.

[0142] In this disclosure, "structural unit derived from (meth)acrylate alkyl ester monomer" refers to a structural unit formed by the addition polymerization of (meth)acrylate alkyl ester monomer. Furthermore, the "(meth)acrylate alkyl ester monomer" in a specific (meth)acrylate resin particle A does not include monomers that are monomers having a carboxyl group or monomers that are monomers having a self-crosslinking group.

[0143] There are no particular restrictions on the types of (meth)acrylate alkyl ester monomers.

[0144] Alkyl methacrylate monomers can be either alkyl acrylate monomers or alkyl methacrylate monomers.

[0145] The alkyl group in the (meth)acrylate monomer can be either unsubstituted or substituent (excluding carboxyl groups, self-crosslinking groups, and hydroxyl groups), but is preferably unsubstituted.

[0146] The alkyl group in the (meth)acrylate monomer can be any one of straight-chain, branched, or cyclic.

[0147] The number of carbon atoms in the alkyl group of the (meth)acrylate monomer is preferably 1 to 18, more preferably 1 to 12, and even more preferably 1 to 8.

[0148] Specific examples of alkyl methacrylate monomers include: methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, n-decyl methacrylate, stearyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, and isobornyl methacrylate.

[0149] As an alkyl acrylate monomer, it is preferably selected from at least one of the groups consisting of n-butyl acrylate, methyl methacrylate and 2-ethylhexyl acrylate.

[0150] <Structural units from other monomers>

[0151] A specific (meth)acrylic resin particle A may also contain structural units from any of the monomers that do not belong to the group consisting of a monomer having a carboxyl group, a monomer having a self-crosslinking group, and a (meth)acrylic alkyl ester monomer (so-called other monomers).

[0152] In this disclosure, "structural unit from other monomers" refers to a structural unit formed by the addition polymerization of other monomers.

[0153] As structural units derived from other monomers, such as those derived from styrene, if a particular (meth)acrylic resin particle A contains structural units derived from styrene, it is possible to impart gloss to the formed adhesive coating.

[0154] In addition, structural units derived from other monomers can be exemplified by: structural units derived from (meth)acrylates having aromatic rings, such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; structural units derived from (meth)acrylate alkoxyalkyl esters, such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; structural units derived from vinyl cyanide, such as acrylonitrile and methacrylonitrile; and structural units derived from vinyl esters, such as vinyl formate, vinyl acetate, vinyl propionate, and vinyl tert-carbonate.

[0155] When a specific (meth)acrylic resin particle A contains structural units from other monomers, it may contain only one type of structural unit from other monomers or more than two types.

[0156] When a particular (meth)acrylic resin particle A contains structural units from other monomers, the content of the structural units from other monomers can be appropriately set within a range that does not impair the effect of the coating composition disclosed herein.

[0157] <<Content of Specific (Meth) Acrylic Resin Particle A>>

[0158] The content of specific (meth)acrylic resin particles A is not particularly limited, but is preferably 85% to 95% by mass, more preferably 87% to 93% by mass, and even more preferably 89% to 91% by mass relative to the adhesive coating.

[0159] [Water-soluble (meth)acrylic resin B]

[0160] The adhesive coating contains water-soluble (meth)acrylic resin B.

[0161] The adhesive coating may contain only one water-soluble (meth)acrylic resin B, or it may contain two or more.

[0162] Here, "water-soluble (meth)acrylic resin B" refers to a (meth)acrylic resin with a solubility of more than 50 mg per 100 g of water at 25°C.

[0163] <Structural units derived from monomers with self-crosslinking groups>

[0164] Water-soluble (meth)acrylic resin B may also contain structural units derived from monomers with self-crosslinking groups.

[0165] If water-soluble (meth)acrylic resin B contains structural units derived from monomers with self-crosslinking groups, it tends to have excellent adhesive strength at high temperatures.

[0166] Furthermore, water-soluble (meth)acrylic resin B may also be free of structural units derived from monomers possessing self-crosslinking groups. That is, water-soluble (meth)acrylic resin B may also be a non-crosslinking resin.

[0167] Specific examples of self-crosslinking groups in water-soluble (meth)acrylic resin B are the same as specific examples of self-crosslinking groups in specific (meth)acrylic resin particles A.

[0168] As a self-crosslinking group, it is preferably at least one selected from the group consisting of N-hydroxymethyl, N-hydroxybutyl, and glycidyl groups.

[0169] Specific examples of monomers having self-crosslinking groups in water-soluble (meth)acrylic resin B are the same as specific examples of monomers having self-crosslinking groups in specific (meth)acrylic resin particles A.

[0170] As a monomer having a self-crosslinking group, it is preferably at least one selected from N-hydroxymethylacrylamide (NMAM) and hydroxyethylacrylamide (HEAA).

[0171] When water-soluble (meth)acrylic resin B contains structural units derived from monomers with self-crosslinking groups, it may contain only one type of structural unit derived from a monomer with self-crosslinking groups, or it may contain two or more types of structural units.

[0172] When the water-soluble (meth)acrylic resin B contains structural units from monomers having self-crosslinking groups, the content of structural units from monomers having self-crosslinking groups is not particularly limited. For example, relative to all structural units of the water-soluble (meth)acrylic resin B, it is preferably 0.1% to 10.0% by mass, more preferably 1.0% to 5.0% by mass, and even more preferably 1.5% to 2.0% by mass.

[0173] If the content of structural units from monomers having self-crosslinking groups in the water-soluble (meth)acrylic resin B is within the above range relative to all structural units of the water-soluble (meth)acrylic resin B, the resulting adhesive coating tends to exhibit higher adhesive strength under high-temperature conditions when fixing electromagnetic steel sheets to each other.

[0174] <Structural units from monomers containing hydroxyl groups>

[0175] Water-soluble (meth)acrylic resin B preferably contains structural units derived from monomers having hydroxyl groups.

[0176] In this disclosure, "structural unit from a monomer having a hydroxyl group" refers to a structural unit formed by the addition polymerization of a monomer having a hydroxyl group. Furthermore, in this disclosure, the hydroxyl group constituting part of a self-crosslinking group is not included in the hydroxyl group of the monomer having a hydroxyl group.

[0177] As a monomer having a hydroxyl group, for example, a monomer having at least one hydroxyl group and one olefinic unsaturated group in a molecule can be cited.

[0178] As an olefinic unsaturated group, there are no particular limitations; examples include vinyl, allyl, vinylphenyl, (meth)acrylamido, and (meth)acryloyl.

[0179] As an olefinic unsaturated group, (meth)acryloyl is preferred.

[0180] Specific examples of monomers containing hydroxyl groups include: 2-(meth)acrylate hydroxyethyl ester, 2-hydroxypropyl acrylate (meth)acrylate, 3-hydroxypropyl acrylate (meth)acrylate, 4-hydroxybutyl acrylate (meth)acrylate, 6-hydroxyhexyl acrylate (meth)acrylate, 10-hydroxydecyl acrylate (meth)acrylate, 12-hydroxylauryl acrylate (meth)acrylate, 3-methyl-3-hydroxybutyl acrylate (meth)acrylate, 1,1-dimethyl-3-hydroxybutyl acrylate (meth)acrylate, 1,3-dimethyl-3-hydroxybutyl acrylate (meth)acrylate, 2,2,4-trimethyl-3-hydroxypentyl acrylate (meth)acrylate, 2-ethyl-3-hydroxyhexyl acrylate (meth)acrylate, glyceryl mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, and poly(ethylene glycol-propylene glycol) mono(meth)acrylate.

[0181] As a monomer having hydroxyl groups, hydroxyalkyl (meth)acrylate is preferred, hydroxyalkyl (meth)acrylate having 2 to 4 carbon atoms is more preferred, 2-hydroxyethyl (meth)acrylate is even more preferred, and 2-hydroxyethyl methacrylate is particularly preferred.

[0182] Water-soluble (meth)acrylic resin B, when containing structural units from monomers having hydroxyl groups, may contain only one type of structural unit from a monomer having hydroxyl groups, or it may contain two or more types of structural units.

[0183] When the water-soluble (meth)acrylic resin B contains structural units from monomers having hydroxyl groups, the content of structural units from monomers having hydroxyl groups is not particularly limited. For example, relative to all structural units of the water-soluble (meth)acrylic resin B, it is preferably 5% to 30% by mass, more preferably 10% to 25% by mass, and even more preferably 15% to 25% by mass.

[0184] If the content of structural units derived from monomers with hydroxyl groups in water-soluble (meth)acrylic resin B is 5% by mass or more relative to all structural units of water-soluble (meth)acrylic resin B, it tends to have excellent appearance, adhesive strength and magnetic properties.

[0185] If the content of structural units from monomers having hydroxyl groups in water-soluble (meth)acrylic resin B is less than 30% by mass relative to all structural units of water-soluble (meth)acrylic resin B, then water-soluble (meth)acrylic resin B tends to have better manufacturing stability.

[0186] <Structural units derived from (meth)acrylate alkyl ester monomers>

[0187] Water-soluble (meth)acrylic resin B preferably contains structural units derived from alkyl (meth)acrylic acid ester monomers.

[0188] Furthermore, the "(meth)acrylate alkyl ester monomer" in water-soluble (meth)acrylate resin B does not include monomers that are monomers with self-crosslinking groups or monomers that are monomers with hydroxyl groups.

[0189] There are no particular restrictions on the types of (meth)acrylate alkyl ester monomers.

[0190] Alkyl methacrylate monomers can be either alkyl acrylate monomers or alkyl methacrylate monomers.

[0191] The alkyl group in the (meth)acrylate monomer can be either unsubstituted or substituent (excluding carboxyl groups, self-crosslinking groups, and hydroxyl groups), but is preferably unsubstituted.

[0192] The alkyl group in the (meth)acrylate monomer can be any one of straight-chain, branched, or cyclic.

[0193] The number of carbon atoms in the alkyl group of the (meth)acrylate monomer is preferably 1 to 12, more preferably 1 to 8, and even more preferably 1 to 4.

[0194] Specific examples of alkyl methacrylate monomers in water-soluble (meth)acrylate resin B are the same as specific examples of alkyl methacrylate monomers in specific (meth)acrylate resin particles A.

[0195] From the viewpoint of water solubility, the (meth)acrylate alkyl ester monomer preferably contains at least one selected from the group consisting of n-butyl acrylate, methyl methacrylate and ethyl acrylate, more preferably contains at least one selected from methyl methacrylate and ethyl acrylate, and even more preferably contains methyl methacrylate.

[0196] The water-soluble (meth)acrylic resin B contains structural units derived from alkyl methacrylate monomers. It may contain only one type of structural unit derived from alkyl methacrylate monomers or more than two types.

[0197] When the water-soluble (meth)acrylic resin B contains structural units derived from alkyl methacrylate monomers, the content of structural units derived from alkyl methacrylate monomers in the water-soluble (meth)acrylic resin B is not particularly limited. For example, it is preferably 40% to 90% by mass, more preferably 40% to 80% by mass, and even more preferably 40% to 70% by mass relative to all structural units of the water-soluble (meth)acrylic resin B.

[0198] <Structural units from other monomers>

[0199] Water-soluble (meth)acrylic resin B may also contain structural units from any of the monomers that do not belong to the group of self-crosslinking monomers, monomers with hydroxyl groups, and (meth)acrylic alkyl ester monomers (so-called other monomers).

[0200] Structural units derived from other monomers include, for example, structural units derived from (meth)acrylates with aromatic rings, such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; structural units derived from (meth)acrylate alkoxyalkyl esters, such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; structural units derived from vinyl cyanide, such as acrylonitrile and methacrylonitrile; and structural units derived from vinyl esters, such as vinyl formate, vinyl acetate, vinyl propionate, and vinyl tert-carbonate.

[0201] Water-soluble (meth)acrylic resin B may contain only one type of structural unit from other monomers, or it may contain two or more types of structural units from other monomers.

[0202] When the water-soluble (meth)acrylic resin B contains structural units from other monomers, the content of the structural units from other monomers can be appropriately set within a range that does not impair the effect of the coating composition disclosed herein.

[0203] <<Content of water-soluble (meth)acrylic resin B>>

[0204] Regarding the content of water-soluble (meth)acrylic resin B in the adhesive coating, the preferred ratio of the mass of specific (meth)acrylic resin particles A to the mass of water-soluble (meth)acrylic resin B ([mass of specific (meth)acrylic resin particles A / mass of water-soluble (meth)acrylic resin B]) is 95 / 5 to 85 / 15.

[0205] If the mass ratio of a specific (meth)acrylic resin particle A to the mass ratio of a water-soluble (meth)acrylic resin B is 95 / 5 to 85 / 15, it tends to have excellent appearance, adhesive strength, and magnetic properties. From this point of view, the mass ratio of a specific (meth)acrylic resin particle A to the mass ratio of a water-soluble (meth)acrylic resin B is preferably 95 / 5 to 90 / 10.

[0206] [Other ingredients]

[0207] The adhesive coating may also contain other components (so-called other components) as needed, without compromising its effectiveness.

[0208] Based on the qualitative analysis of the components contained in the adhesive coating of the electromagnetic steel sheet with adhesive coating or the laminated iron core obtained by stacking electromagnetic steel sheets with adhesive coating, the weight distribution of fragments based on TOFMS can be performed to estimate the component ratio.

[0209] Analytical samples of electromagnetic steel sheets with adhesive coatings can be collected by cutting out the coated portion using a precision cutter. Alternatively, in cases where a laminated core has been formed, samples can be collected using the same method after peeling several electromagnetic steel sheets from the laminated core.

[0210] (Manufacturing method of electromagnetic steel sheet with adhesive coating)

[0211] (Methods for forming adhesive coatings)

[0212] The electromagnetic steel sheet with adhesive coating disclosed herein is independent of the manufacturing method. As long as it has the above-mentioned features, it can perform its function. However, it can be obtained, for example, by a manufacturing method including the following steps.

[0213] (I) Coating process, wherein an adhesive coating liquid is applied to at least a portion of one or both sides of an electromagnetic steel sheet to obtain a coated steel sheet.

[0214] (II) The coating process involves heating the coated steel plate to a drying temperature of 100~200°C at a heating rate of less than 6.0°C / second, and drying it in a temperature range of 10~60 seconds from the drying temperature to the drying temperature -10°C, thereby forming an adhesive coating on the surface of the electromagnetic steel plate.

[0215] 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.

[0216] Each process step is explained.

[0217] —Coating process—

[0218] In the coating process, an adhesive coating liquid (hereinafter also referred to as "the coating liquid of this disclosure" or "the coating composition of this disclosure") is applied to at least a portion of one or both sides of the electromagnetic steel sheet to obtain a coated steel sheet.

[0219] The coating liquid (coating composition) disclosed herein comprises (meth)acrylic resin particles A, water-soluble (meth)acrylic resin B, and a water-containing medium.

[0220] In the coating liquid of this disclosure, specific (meth)acrylic resin particles A exist in a state of dispersion in a water-containing medium.

[0221] In addition, water-soluble (meth)acrylic resin B exists in a state of being dissolved in a water-containing medium.

[0222] By applying such a coating liquid and then allowing it to dry, the adhesive coating of this embodiment described above is obtained.

[0223] [water]

[0224] The coating solution disclosed herein contains water.

[0225] There are no specific restrictions on the type of water.

[0226] 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.

[0227] The water content in the coating liquid disclosed herein is not particularly limited, but is preferably 35% to 50% by mass, more preferably 40% to 45% by mass, relative to the total mass of the coating composition.

[0228] [Other ingredients]

[0229] The coating liquid disclosed herein may, as needed, contain other components (so-called other components) besides those mentioned above, without impairing its effectiveness.

[0230] Other components include, for example, aqueous media other than water.

[0231] As a water-based medium other than water, examples include water-miscible organic solvents.

[0232] 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.

[0233] In addition, other components include various additives such as preservatives, wetting agents, and defoamers.

[0234] [Method for manufacturing coating liquid]

[0235] The method for manufacturing the coating liquid disclosed herein is not particularly limited.

[0236] The coating liquid disclosed herein can be manufactured, for example, by mixing a dispersion of a specific (meth)acrylic resin particle A with an aqueous solution of a water-soluble (meth)acrylic resin B.

[0237] There are no particular restrictions on the mixing method.

[0238] As a mixing method, one example is mixing by stirring.

[0239] Stirring can be done using general stirring utensils or stirring devices.

[0240] There is no particular limitation on the stirring temperature, but it is preferably 20°C to 30°C.

[0241] —Adhesive coating process—

[0242] In the coating process, an adhesive coating is formed on the surface of the electromagnetic steel sheet by heating the coated steel sheet (coated steel sheet) with coating liquid at a heating rate of less than 6.0℃ / second to a drying temperature of 100~200℃ (the maximum temperature reached by the material), and then drying it in the temperature range of drying temperature to (drying temperature -10℃) for 10~90 seconds.

[0243] The drying time (the time the material temperature is maintained at the drying temperature -10℃ to the drying temperature) is preferably set to 30~60 seconds. The heating rate is calculated based on the time until the drying temperature (the highest temperature the material can reach).

[0244] If the drying temperature exceeds 200°C, there is a risk of resin oxidation. If the drying temperature is below 100°C or the drying time is less than 10 seconds, the resin will not dry sufficiently.

[0245] If the drying time exceeds 90 seconds, it becomes a disadvantage in terms of productivity.

[0246] Furthermore, if the heating rate exceeds 6.0°C / second, the film cannot be properly manufactured, resulting in insufficient adhesive strength. It is generally believed that slowing down the heating rate requires extending the furnace length or reducing the production line speed, which is not preferable in terms of equipment constraints and productivity. However, in the manufacturing method of the electromagnetic steel sheet with adhesive coating in this embodiment, based on the novel insight that the above-mentioned effect is obtained by slowing down the heating rate, the heating rate is actually slowed down.

[0247] The formation of an adhesive coating using a coating liquid disclosed herein can be exemplified by applying the coating liquid to the surface of an electromagnetic steel sheet using known coating methods such as roller coating or spray coating, followed by drying.

[0248] The concentration of solid components in the coating liquid is preferably 5 to 40% by mass, more preferably 10 to 25% by mass.

[0249] The preferred drying method is a heating furnace using irradiation, but it can also be a hot air furnace or other methods.

[0250] [Laminated iron core]

[0251] 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.

[0252] Here, the cured film of the adhesive coating refers to a film that exhibits adhesive ability by heating and pressurizing the stacked electromagnetic steel plates with the adhesive coating, thereby promoting the cross-linking of the (meth)acrylic resin particles A in the adhesive coating.

[0253] Specifically, as a laminated iron core of this disclosure, for example, a laminated iron core can be formed by punching out an electromagnetic steel plate with an adhesive coating as disclosed in this disclosure, making a punched component, stacking the punched component, and integrating it by heating and pressurizing.

[0254] The stacking factor of the laminated iron core disclosed herein is preferably 96~98%.

[0255] Figure 2This 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 is formed by connecting eight stamping members 11 with adhesive coatings to form a ring, and stacking the connected ring-shaped stamping members 11 into eight layers to form a laminated body 13.

[0256] 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.

[0257] 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 shown can be designed according to the purpose.

[0258] (Manufacturing method of laminated iron core)

[0259] The laminated iron core disclosed herein is manufactured, for example, through the following processes.

[0260] (III) The blanking process involves blanking the electromagnetic steel sheet with adhesive coating disclosed herein to obtain a blanked component.

[0261] (IV) Lamination process: multiple sheets of the punched components are laminated to obtain a laminate.

[0262] (V) Bonding process: The laminate is heated to a temperature range of 200~300°C and held at a pressure of 0.5~10MPa for 30~60 minutes within the range of the pressure temperature to the pressure temperature -10°C.

[0263] Each process step is explained.

[0264] —Punching process—

[0265] In the blanking process, an electromagnetic steel sheet with an adhesive coating is blanked to obtain a component with a specified shape (a blanked component). There are no restrictions on the blanking method.

[0266] —Layering process—

[0267] In the lamination process, the punched components are stacked with an adhesive coating spaced between each other on electromagnetic steel sheets. This results in a laminated body.

[0268] — Bonding process —

[0269] In the bonding process, the laminate is heated to a pressure temperature (the highest temperature the material can reach) in the range of 200~300°C, and held at a pressure of 0.5~10 MPa for 30~60 minutes within the range of the pressure temperature to -10°C. This causes the cross-linking of the (meth)acrylic resin particles A in the adhesive coating to progress, resulting in the curing of the adhesive coating. The cured adhesive coating then exhibits adhesive properties, bonding the electromagnetic steel sheets together.

[0270] Based on these operations, the stacked iron core of this disclosure is obtained.

[0271] Electromagnetic steel sheets with adhesive coatings can be bonded to each other by having the cured adhesive coatings of the sheets facing each other, or by having the cured adhesive coating of one sheet facing the uncoated side of another sheet.

[0272] The preferred pressurization temperature is 200~300℃, the preferred pressurization pressure is 0.5~10MPa, and the preferred holding time is 30~60 minutes.

[0273] (Applications of laminated iron cores)

[0274] 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.

[0275] Example

[0276] The coating compositions of this disclosure are described in more detail below through examples. This disclosure is not limited to the following examples without departing from its spirit.

[0277] [Example 1]

[0278] 1. Manufacturing of (meth)acrylic resin particles A

[0279] In a stainless steel container, place 56 parts by weight of n-butyl acrylate [n-BA; alkyl acrylate monomer], 168 parts by weight of methyl methacrylate [MMA; alkyl methacrylate monomer], 128 parts by weight of styrene [St; other monomers], 40 parts by weight of methacrylic acid [MMA; monomer with carboxyl groups], and 8 parts by weight of hydroxyethyl acrylamide [HEAA; monomer with self-crosslinking groups] and mix them to prepare a monomer mixture.

[0280] Next, in another stainless steel container, 172.0 parts by weight of deionized water, 2.7 parts by weight of NOIGEN (registered trademark) EA-197D [Daiichi Kogyo Pharmaceutical Co., Ltd.] as a nonionic surfactant, 4.1 parts by weight of EMULGEN (registered trademark) A-60 [Kao Corporation], and 2.7 parts by weight of NEOPELEX (registered trademark) G-65 [Kao Corporation] as an anionic surfactant were added and stirred to dissolve the surfactants, thus preparing an aqueous surfactant solution.

[0281] Next, the monomer mixture prepared above was slowly added to the surfactant aqueous solution while stirring with a stirrer to emulsify it, thus preparing a pre-emulsion. This pre-emulsion was then used for polymerization.

[0282] Polymerization was carried out in a constant temperature bath in a 7L (liters; the same applies below) flask equipped with a reflux cooling tube, a stirring device, a nitrogen inlet tube, a pre-emulsion droplet pump [trade name: HIGH SERA PUMP V-10, manufactured by IWAKI Co., Ltd.], and a polymerization initiator addition device [trade name: metering pump MP-2000, manufactured by Tokyo Riko Machinery Co., Ltd.]. Specifically, polymerization was carried out as follows.

[0283] Add 162.4 parts by weight of deionized water to the flask, then add a portion (17.5 parts by weight) of the pre-emulsion prepared above. Purge nitrogen into the flask at a flow rate of 300 ml / min while stirring at an arbitrary rotation speed [Standard condition: 240 rpm (revolutions per minute); the same applies below)], allowing the internal temperature of the flask to rise to an arbitrary reaction temperature [Standard condition: 62°C]. After the internal temperature stabilizes, add 2.3 parts by weight of 24% ammonium persulfate aqueous solution [polymerization initiator] and 2.3 parts by weight of 20% sodium bisulfite aqueous solution [reducing agent], adjusting the nitrogen flow rate to 50 ml / min. Once the temperature inside the flask has risen, add the remaining pre-emulsion (564 parts by weight) dropwise over 270 minutes, and then add 63.4 parts by weight of 2.4% ammonium persulfate aqueous solution [polymerization initiator] and 63.4 parts by weight of 2.0% sodium bisulfite aqueous solution [reducing agent] dropwise over 360 minutes. Thirty minutes after the addition of ammonium persulfate aqueous solution and sodium bisulfite, 6.4 parts by mass of 6.9% tert-butyl hydrogen peroxide aqueous solution [polymerization initiator] and 6.4 parts by mass of 4.4% sodium hydroxymethanesulfinate aqueous solution [reducing agent] were added dropwise over 30 minutes. After 150 minutes from the end of the pre-emulsion addition, the mixture was cooled to 30°C, thus ending the polymerization reaction.

[0284] An aqueous dispersion of (meth)acrylic resin particles A was obtained by adding 1.3 parts by weight of a preservative [trade name: TOP SIDE350, manufactured by Permachem Asia Co., Ltd.] and a wetting agent [trade name: SURFYNOL (registered trademark) 440, manufactured by Nissin Chemical Industry Co., Ltd.] to an emulsified polymer obtained by polymerization reaction.

[0285] 2. Manufacturing of water-soluble (meth)acrylic resin B

[0286] In a stainless steel container, 126 parts by weight of methyl methacrylate [MMA; alkyl methacrylate monomer], 48 parts by weight of ethyl acrylate [EA; alkyl methacrylate monomer], 60 parts by weight of acrylic acid [AA; a monomer with a carboxyl group], 60 parts by weight of 2-hydroxyethyl methacrylate [2HEMA; a monomer with a hydroxyl group], and 6 parts by weight of hydroxyethyl acrylamide [HEAA; a monomer with a self-crosslinking group] are placed and mixed to prepare a monomer mixture.

[0287] Next, in another stainless steel container, 121.0 parts by weight of deionized water and 4.5 parts by weight of LATEMUL (registered trademark) E-118B [Kao Corporation] as an anionic surfactant were added and stirred to dissolve them, thus preparing an aqueous surfactant solution.

[0288] Next, the monomer mixture prepared above was slowly added to the surfactant aqueous solution while stirring with a stirrer to emulsify it, thus preparing a pre-emulsion. This pre-emulsion was then used for polymerization.

[0289] Polymerization is carried out in a constant temperature bath in a 7L flask equipped with a reflux cooling tube, a stirring device, a nitrogen inlet tube, a pre-emulsion droplet pump [trade name: HIGH SERA PUMP V-10, manufactured by IWAKI Co., Ltd.], and a polymerization initiator addition device [trade name: metering pump MP-2000, manufactured by Tokyo Riko Machinery Co., Ltd.]. Specifically, polymerization is carried out as follows.

[0290] Add 415 parts by weight of deionized water and 7.0 parts by weight of LATEMUL (registered trademark) E-118B [Kao Corporation] as an anionic surfactant to the flask, followed by 8.5 parts by weight of the pre-emulsion prepared above. Purge nitrogen gas into the flask at a flow rate of 300 ml / min, stirring at an arbitrary speed [standard condition: 150 rpm] while raising the internal temperature of the flask to an arbitrary reaction temperature [standard condition: 60°C]. Then add 1.0 part by weight of 69.0% by weight tert-butyl hydrogen peroxide aqueous solution [polymerization initiator] and 2.5 parts by weight of 10.0% by weight sodium hydroxymethanesulfinate aqueous solution [reducing agent]. After the internal temperature stabilizes, adjust the nitrogen flow rate to 50 ml / min. After adjustment, the remaining pre-emulsion (456.6 parts by mass) was added dropwise over 180 minutes, while simultaneously adding 24.5 parts by mass of 6.9% tert-butyl hydrogen peroxide aqueous solution [polymerization initiator], 24.5 parts by mass of 1.2% sodium hydroxymethanesulfinate aqueous solution [reducing agent], and 39.6 parts by mass of 14.7% 2-mercaptoethanol [chain transfer agent] over 180 minutes to obtain an aqueous dispersion of (meth)acrylic resin particles. 58 parts by mass of 25.0% ammonia water (alkaline aqueous solution) were added to the obtained aqueous dispersion of (meth)acrylic resin particles to dissolve the (meth)acrylic resin particles in water, yielding water-soluble (meth)acrylic resin B.

[0291] 3. Manufacturing of coating liquid (coating composition)

[0292] 300.0 parts by weight of an aqueous dispersion of (meth)acrylic resin particles A (137.1 parts by weight as solids) and 48.1 parts by weight of an aqueous solution of water-soluble (meth)acrylic resin B (15.2 parts by weight as solids) were mixed, and an appropriate amount of deionized water was added to obtain a coating solution with a solids concentration of 43.5% by weight.

[0293] The "solids concentration" mentioned here refers to the total mass ratio of (meth)acrylic resin particles A and water-soluble (meth)acrylic resin B in the coating composition. The same applies to the coating liquids manufactured below.

[0294] 4. Fabrication of electromagnetic steel sheets with adhesive coating

[0295] First, prepare a non-oriented electromagnetic steel sheet with a thickness of 0.25 mm and a width of 100 mm, by mass percentage: Si: 3.0%, Mn: 0.2%, Al: 0.5%, with the remainder consisting of Fe and impurities.

[0296] Next, after applying the coating liquid to one side of the electromagnetic steel plate, the electromagnetic steel plate is heated at a heating rate of 5.0℃ / second until the surface temperature of the steel plate reaches 170℃ and held for 60 seconds to allow the coating film to dry, forming an adhesive film with a thickness of 3μm.

[0297] In this way, an electromagnetic steel sheet with an adhesive coating is obtained.

[0298] [Examples 2-8, Comparative Examples 1-6]

[0299] Except that the monomer compositions of (meth)acrylic resin particles A and water-soluble (meth)acrylic resin B are respectively set to the monomer compositions shown in Table 1, and the mass ratio [A / B] of (meth)acrylic resin particles A to water-soluble (meth)acrylic resin B is set to the mass ratio shown in Table 1, the same operation as in Example 1 was performed to obtain a coating composition with a solid content concentration of 43.5% by mass.

[0300] Then, using the obtained coating composition, an electromagnetic steel sheet with an adhesive coating was obtained in the same manner as in Example 1.

[0301] Furthermore, in Comparative Example 5, a coating composition without (meth)acrylic resin particles A was obtained.

[0302] In addition, in Comparative Example 6, a coating composition that does not contain water-soluble (meth)acrylic resin B was obtained.

[0303] [evaluate]

[0304] (Weight-average molecular weight (Mw) of the adhesive coating before heating and weight-average molecular weight (Mw) of the soluble components of the adhesive coating after heating)

[0305] The weight-average molecular weight (Mw) of the adhesive coating before heating and the weight-average molecular weight (Mw) of the soluble components of the adhesive coating after heating in the electromagnetic steel sheets with adhesive coatings in each example were determined according to the above method.

[0306] (Adhesive strength)

[0307] Two 30mm × 60mm veneer test pieces were cut from the electromagnet steel sheets with adhesive coatings in each example. The 30mm × 10mm ends of the two veneer test pieces were overlapped with their adhesive coatings facing each other. The two overlapping veneer test pieces were heated and pressurized at a temperature of 250°C, a pressure of 2MPa, and a holding time (heating and pressurizing) of 1 minute to obtain the adhesive plate for bonding strength testing.

[0308] The shear bond strength was measured as follows when the steel plate was at room temperature (25℃).

[0309] —Tensile testing apparatus—

[0310] • Automatic plotter AGS-10kNX (Shimadzu Corporation)

[0311] —Measurement conditions—

[0312] • Tensile method: Shear tensile test

[0313] • Tensile temperature: 25℃

[0314] • Stretching speed: 50mm / minute

[0315] The tensile test was performed with n=5 until fracture, and the average of the maximum strength until fracture was taken as the shear bond strength.

[0316] Then, the value obtained by dividing the shear bond strength by the bonding area of ​​the two veneer test pieces is taken as the room temperature bond strength.

[0317] If the bond strength is above 6.0 MPa, it is considered to have sufficient bond strength.

[0318] In addition, two 30mm×60mm single-plate test pieces were cut from the electromagnetic steel plates with adhesive coatings in each example. The adhesive plates were overlapped with their 30mm×10mm ends facing each other with their adhesive coatings facing each other. The adhesive plates were placed in an atmosphere of 150°C. Under the same conditions as at room temperature, the shear bond strength was measured with the steel plate temperature at 150°C.

[0319] Then, the value obtained by dividing the shear bond strength by the bonding area of ​​the two veneer test pieces is taken as the bond strength at 150℃.

[0320] If the bond strength is above 2.0 MPa, it is considered to have sufficient bond strength.

[0321] (magnetic properties)

[0322] Two 55mm x 55mm single-layer test pieces were cut from the electromagnet steel sheet with adhesive coating in each example. Then, the two single-layer test pieces were overlapped with their adhesive coatings facing each other. The two overlapping single-layer test pieces were heated and pressurized at a temperature of 250°C, a pressure of 2MPa, and a holding time (heating and pressurizing) of 1 minute to obtain the bonded board.

[0323] The iron loss in the rolling direction and the rolling right angle direction of the obtained laminated samples was measured by the single-plate magnetic determination method specified in JIS 2556:2015, and the average value of the iron loss W10 / 400 in the rolling direction and the rolling right angle direction was calculated.

[0324] If the iron loss is below 10.9 W / kg, it is judged to have excellent magnetic properties.

[0325] (Appearance)

[0326] Three 5mm square test pieces were cut from the electromagnetic steel sheet with adhesive coating in each example to obtain the test pieces.

[0327] Three areas on the adhesive coating surface of each test piece were observed using a scanning electron microscope at 100x magnification. A total of nine fields of view were observed.

[0328] Then, evaluate according to the following evaluation criteria, and classify A and B as qualified.

[0329] A: No coating defects such as cracks, fissures, or peeling were found.

[0330] B: The area with coating defects is less than 10%.

[0331] C: The area ratio of coating defects is greater than 10% but less than 30%.

[0332] D: The area ratio of coating defects is over 30%.

[0333] The details of the abbreviations for each of the monomers listed in Table 1 are as follows.

[0334] <Monomers with self-crosslinking groups>

[0335] “NMAM”: N-hydroxymethylacrylamide

[0336] “NBMA”: N-hydroxybutylacrylamide

[0337] Monomers with self-crosslinking groups and hydroxyl groups

[0338] "HEAA": Hydroxyethylacrylamide

[0339] <Monomers with carboxyl groups>

[0340] “MAA”: Methacrylic acid

[0341] “AA”: Acrylic acid

[0342] <Monomers with hydroxyl groups>

[0343] “2HEMA”: 2-Hydroxyethyl methacrylate

[0344] <(meth)acrylate alkyl ester monomer>

[0345] “n-BA”: n-Butyl acrylate

[0346] “MMA”: Methyl methacrylate

[0347] “2EHA”: 2-Ethylhexyl acrylate

[0348] “EA”: Ethyl acrylate

[0349] <Other Individuals>

[0350] "St": Styrene

[0351] In Table 1, an empty column in the column for the composition of a single component means that no single component matching that column has been used.

[0352] In Table 1, the values ​​recorded in the column for monomer composition are all converted values ​​of solid components (parts by mass).

[0353] [Table 1]

[0354]

[0355] [Table 2]

[0356]

[0357] Based on the above results, it can be seen that in this embodiment, compared with the comparative example, the appearance, bonding strength at room temperature to high temperature, and magnetic properties are all superior.

[0358] Industrial availability

[0359] According to the above-described manner of this disclosure, an electromagnetic steel sheet with an adhesive coating, exhibiting excellent bonding strength and magnetic properties from room temperature to high temperature, a laminated iron core using the electromagnetic steel sheet, and a method for manufacturing the same are provided.

[0360] Explanation of reference numerals in the attached figures

[0361] 10 Electromagnetic steel sheet with adhesive coating

[0362] 10A Electromagnetic Steel Sheet

[0363] 10B Adhesive Coating

[0364] 10C Adhesive Coating

[0365] 11. Punching components of electromagnetic steel sheets with adhesive coating

[0366] 100-layer laminated iron core

Claims

1. An electromagnetic steel plate with an adhesive coating, comprising: Electromagnetic steel sheet; and An adhesive coating is provided on at least a portion of one or both sides of the electromagnetic steel plate. The adhesive coating comprises (meth)acrylic resin particles A and water-soluble (meth)acrylic resin B, wherein the (meth)acrylic resin particles A contain structural units derived from monomers having self-crosslinking groups. The weight-average molecular weight of the adhesive coating is 150,000 to 250,000.

2. The electromagnetic steel plate with adhesive coating as described in claim 1, The weight-average molecular weight of the soluble components of the adhesive coating after heating at 200°C for 5 minutes is 50,000 to 100,000.

3. The electromagnetic steel plate with adhesive coating as described in claim 1, The water-soluble (meth)acrylic resin B is a (meth)acrylic resin containing structural units derived from monomers with self-crosslinking groups.

4. The electromagnetic steel plate with adhesive coating as described in claim 1, The mass ratio of the (meth)acrylic resin particles A to the mass ratio of the water-soluble (meth)acrylic resin B is 95 / 5 to 85 / 15.

5. The electromagnetic steel plate with adhesive coating as described in claim 1, The self-crosslinking group of the (meth)acrylic resin particle A is selected from at least one group consisting of N-hydroxymethyl, N-hydroxybutyl and glycidyl groups.

6. A layered iron core, It has multiple electromagnetic steel plates with adhesive coatings as described in any one of claims 1 to 5 stacked together, and the electromagnetic steel plates are bonded to each other by the curing film of the adhesive coating.

7. The laminated iron core as described in claim 6, The stacking factor is 96-98%.

8. A method for manufacturing an electromagnetic steel sheet with an adhesive coating, as described in claim 1, comprising: A coating process involves applying an adhesive coating liquid to at least a portion of one or both sides of an electromagnetic steel sheet to obtain a coated steel sheet. The adhesive coating liquid comprises (meth)acrylic resin particles A and a water-soluble (meth)acrylic resin B. The (meth)acrylic resin particles A contain structural units derived from monomers having self-crosslinking groups. The coating process involves heating the coated steel sheet to a drying temperature of 100-200°C at a heating rate of less than 6.0°C / second, and then drying it in a temperature range from the drying temperature to -10°C for 10-90 seconds to form an adhesive coating on the surface of the electromagnetic steel sheet.

9. The method for manufacturing an electromagnetic steel sheet with an adhesive coating as described in claim 8, characterized in that, The mass ratio of the (meth)acrylic resin particles A in the coating liquid for forming the adhesive film to the mass ratio of the water-soluble (meth)acrylic resin B is 95 / 5 to 85 / 15.

10. A method for manufacturing a laminated iron core, as described in claim 6, comprising: The blanking process involves blanking the electromagnetic steel sheet with the adhesive coating to obtain a blanked component; The lamination process involves stacking multiple sheets of the punched components to obtain a laminated body; and In the bonding process, the laminate is heated to a pressure temperature in the range of 200~300℃, and held at a pressure of 0.5~10MPa for 30~60 minutes within the range of the pressure temperature to the pressure temperature -10℃, thereby curing the adhesive coating to form the cured film.

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