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 that is provided on at least a portion of one or both surfaces of the electromagnetic steel sheet and contains a crosslinkable thermoplastic resin (A) and a thermoplastic resin (B) other than the crosslinkable thermoplastic resin (A), the peak temperature of the logarithmic attenuation curve measured by a rigid oscillator test in the adhesive film is 130-150 DEG C, and P1 / P2, which is the peak ratio of the peak value P1 of the logarithmic attenuation of the logarithmic attenuation curve after heating at 200 DEG C for 1 minute to the peak value P2 of the logarithmic attenuation of the logarithmic attenuation curve before heating, is 0.70-1.30.

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 disclosure asserts priority based on Japanese Patent Application No. 2023-163603 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 more than 10% by mass of 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 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, adhesive strength and magnetic properties 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 temperatures ranging from room temperature to high temperatures.

[0022] Therefore, in electromagnetic steel sheets with adhesive coatings, it is desirable to further improve the adhesive strength and magnetic properties at temperatures ranging from room temperature to 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 temperatures ranging from room temperature to 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> One aspect of this disclosure is an electromagnetic steel plate with an adhesive coating, comprising an electromagnetic steel plate and an adhesive coating, wherein the adhesive coating is disposed on at least a portion of one or both sides of the electromagnetic steel plate, and comprises a cross-linked thermoplastic resin A and a thermoplastic resin B other than the cross-linked thermoplastic resin A, wherein the peak temperature of the logarithmic decay rate curve of the adhesive coating, as determined by a rigid oscillator test, is 130~150°C, and the peak ratio of the peak value P1 of the logarithmic decay rate curve after heating at 200°C for 1 minute to the peak value P2 of the logarithmic decay rate curve before heating, i.e., P1 / P2, is 0.70~1.30.

[0027] <2> exist <1> In the aforementioned electromagnetic steel plate with adhesive coating, P2 can also be 0.07~0.30.

[0028] <3> exist <1> or <2> In the aforementioned electromagnetic steel plate with adhesive coating, the pencil hardness of the adhesive coating before heating can also be 3H~4H.

[0029] <4> exist <1> ~ <3> In any of the electromagnetic steel plates with adhesive coatings described herein, P1 may also be 0.05 to 0.25.

[0030] <5> exist <1> ~ <4> In any one of the electromagnetic steel plates with adhesive coatings, the heated pencil hardness of the adhesive coating can also be 5H to 6H.

[0031] <6> exist <1> ~ <5> In any of the electromagnetic steel sheets with adhesive coatings described herein, the crosslinked thermoplastic resin A may also be one or more resins selected from the group consisting of (meth)acrylic resins and polyester resins.

[0032] <7> In other types of laminated cores disclosed herein, multiple layers are stacked as follows: <1> ~ <6> 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.

[0033] <8> exist <7> In the aforementioned stacked iron core, the stacking factor can also be 96~98%.

[0034] <9> The other method of manufacturing an electromagnetic steel sheet with an adhesive coating disclosed herein includes the following steps: a coating step, in which an adhesive coating forming coating liquid is applied to at least a portion of one or both sides of the electromagnetic steel sheet to obtain a coated steel sheet; and a coating forming step, in which the coated steel sheet is heated to a drying temperature of 100 to 200°C at a heating rate of 6.0°C / second or less, and dried in a temperature range of 10 to 90 seconds from the drying temperature to the drying temperature -10°C, thereby forming an adhesive coating on the surface of the electromagnetic steel sheet.

[0035] <10> like <9> In the method for manufacturing an electromagnetic steel sheet with an adhesive coating, in the coating process, the coating liquid for forming the adhesive coating includes a crosslinked thermoplastic resin A and a thermoplastic resin B other than the crosslinked thermoplastic resin A, and the mass ratio of the crosslinked thermoplastic resin A to the thermoplastic resin B can also be 97 / 3 to 70 / 30.

[0036] <11> The manufacturing method of the laminated iron core of other embodiments disclosed herein includes the following steps: a coating step, in which an adhesive coating liquid is applied to at least a portion of one or both sides of an electromagnetic steel plate to obtain a coated steel plate; a coating forming step, in which the coated steel plate is heated to a drying temperature of 100-200°C at a heating rate of 6.0°C / second or less, and dried in a temperature range of 10-90 seconds from the drying temperature to -10°C to form an adhesive coating on the surface of the electromagnetic steel plate to obtain an electromagnetic steel plate with an adhesive coating; a punching step, in which the electromagnetic steel plate with an adhesive coating is punched to obtain a punched component; a lamination step, in which multiple punched components are stacked to obtain a laminate; and a bonding step, in which the laminate is heated to a pressure temperature in a temperature range of 200-300°C, and held under a pressure of 0.5-10 MPa for 1-60 minutes in the range of the pressure temperature to -10°C.

[0037] Invention Effects

[0038] 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 temperatures ranging from room temperature to high temperature, a laminated iron core using the electromagnetic steel sheet, and a method for manufacturing the same are provided. Attached Figure Description

[0039] Figure 1 This is a schematic diagram illustrating an example of an electromagnetic steel sheet with an adhesive coating according to the present disclosure.

[0040] Figure 2This is a schematic diagram illustrating an example of a laminated iron core according to the present disclosure. Detailed Implementation

[0041] The following is an explanation of this disclosure.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] In this disclosure, a combination of two or more preferred methods is a more preferred method.

[0046] In this disclosure, the amount of each component in the coating liquid for forming an adhesive film is the sum of the amounts of the multiple substances present in the coating liquid for forming an adhesive film, unless otherwise specified.

[0047] In this disclosure, "mass%" and "weight%" have the same meaning, and "parts of mass" and "parts of weight" have the same meaning.

[0048] [Electromagnetic steel sheet with adhesive coating]

[0049] 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 ).

[0050] The adhesive coating comprises a crosslinked thermoplastic resin A from the coating liquid for forming the adhesive coating and a thermoplastic resin B other than the crosslinked thermoplastic resin A.

[0051] Furthermore, the peak temperature of the logarithmic decay rate curve measured by the rigid body oscillator test in the adhesive coating is 130~150℃, and the peak ratio (P1 / P2) of the peak value P1 of the logarithmic decay rate curve after heating at 200℃ for 1 minute to the peak value P2 of the logarithmic decay rate curve before heating is 0.70~1.30.

[0052] 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.

[0053] According to the above structure, the electromagnetic steel sheet with adhesive coating disclosed herein exhibits excellent adhesive strength and magnetic properties at temperatures ranging from room temperature (25°C) to high temperature (150°C) (and also excellent magnetic properties as a laminated iron core).

[0054] The rationale is speculated as follows: By applying a cross-linking thermoplastic resin 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 thermoplastic resin B within the aforementioned logarithmic decay rate range to mitigate compressive stress, excellent magnetic properties are obtained.

[0055] The details of the electromagnetic steel sheet with adhesive coating disclosed herein will be described below.

[0056] (Electromagnetic steel sheet)

[0057] Electromagnetic steel sheets are steel sheets that are bonded and coated with a film, and there are no particular restrictions.

[0058] Electromagnetic steel sheets can be either non-oriented or oriented.

[0059] Specifically, as an electromagnetic steel sheet, for example, non-oriented electromagnetic steel sheet of JIS C 2552:2014, oriented electromagnetic steel sheet of JIS C 2553:2019, non-oriented thin electromagnetic steel sheet or oriented thin electromagnetic steel sheet of JIS C 2558:2021 can be used.

[0060] (Adhesive coating)

[0061] 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.

[0062] However, the area of ​​the adhesive coating relative to one side of the electromagnetic steel sheet (in terms of area ratio) can be set to 60% or more, 80% or more, or 100%.

[0063] [Logarithmic decay rate curve]

[0064] - Peak temperature of logarithmic decay rate -

[0065] The peak temperature of the logarithmic decay rate curve in the adhesive coating, as determined by the rigid body oscillator test, is 130~150℃.

[0066] If the peak temperature of the logarithmic decay rate curve is less than 130℃, the bond strength will decrease.

[0067] If the peak temperature of the logarithmic decay rate curve exceeds 150°C, the bonding strength is too high, the adhesive coating becomes too hard, and the magnetic properties deteriorate.

[0068] Therefore, the peak temperature of the logarithmic decay rate is set within the above-mentioned range. The peak temperature of the logarithmic decay rate is preferably 130~145℃, more preferably 130~140℃.

[0069] Here, the peak temperature of the logarithmic decay rate curve is represented in the logarithmic decay rate curve, which shows the temperature at which the logarithmic decay rate reaches its maximum value.

[0070] - Peak ratio (P1 / P2) -

[0071] The peak value ratio (P1 / P2) of the logarithmic decay rate curve after heating at 200℃ for 1 minute in the adhesive coating is 0.70~1.30 to the peak value P2 of the logarithmic decay rate curve before heating.

[0072] If the peak ratio (P1 / P2) is less than 0.70, the bond strength is too high, the bond coating becomes too hard, and the magnetic properties deteriorate.

[0073] If the peak ratio (P1 / P2) exceeds 1.30, the bond strength decreases.

[0074] Therefore, the peak ratio (P1 / P2) is set within the range described above. The peak ratio (P1 / P2) is preferably 0.80 to 1.20, more preferably 0.90 to 1.10.

[0075] Here, the peak value of the logarithmic decay rate curve represents the maximum value of the logarithmic decay rate in the logarithmic decay rate curve that represents the relationship between temperature and logarithmic decay rate.

[0076] -P1, P2-

[0077] The peak value P1 of the logarithmic decay rate curve of the adhesive coating before heating is preferably 0.07~0.30.

[0078] If P1 is less than 0.07, the adhesive strength will decrease as it cannot soften during heat pressing. If it exceeds 0.30, adhesion is likely to occur (adhesion caused by the weight of the roll material during transport).

[0079] In addition, the peak value P2 of the logarithmic decay rate curve of the adhesive coating after heating at 200°C for 1 minute is preferably 0.05~0.25.

[0080] If P2 is less than 0.05, the adhesive coating becomes too rigid, and the magnetic properties deteriorate. If it exceeds 0.25, the adhesive strength decreases.

[0081] The peak temperature, P1, P2, and peak ratio (P1 / P2) of the logarithmic decay rate curve can be adjusted according to the type and ratio of crosslinked thermoplastic resin A and thermoplastic resin B.

[0082] In addition, the peak temperature and peak ratio (P1 / P2) of the logarithmic decay rate curve can also be adjusted according to the type and amount of crosslinking agent and the coating formation conditions described later.

[0083] - Peak temperature and peak value determination method for logarithmic decay rate -

[0084] The peak temperature and peak value of the logarithmic decay rate were determined according to the rigid body oscillator test specified in ISO 12013-2:2012, using a rigid body oscillator-type physical property test apparatus. Specifically, the determination was performed as follows.

[0085] Test pieces measuring 20mm × 60mm were collected from the electromagnetic steel plate with adhesive coating of the test object.

[0086] The test piece is placed on the heating and cooling module of the rigid oscillator-type physical property testing device. The edge of the cylinder (pendulum) is placed on the adhesive coating surface (measuring surface) of the test piece.

[0087] Then, using a rigid oscillator-type physical property testing device, the pendulum was heated to a temperature ranging from room temperature to 300°C at a heating rate of 10°C / minute, and the free oscillation period and amplitude were measured. Here, the heating rate of 10°C / minute means that the temperature was measured more than once every 6.0 seconds, and the heating rate was always 10°C / minute when calculating the temperature within any 30-second interval.

[0088] Next, based on the analysis of the pendulum's free oscillation period and oscillation amplitude, the logarithmic decay rate for each measured temperature is calculated, and the logarithmic decay rate relative to the measured temperature is plotted to obtain the logarithmic decay rate curve.

[0089] In addition, the apparatus and conditions used for the measurement are as follows.

[0090] Test apparatus: A&D RPT-3000W rigid body oscillator physical property test apparatus

[0091] Rigid body oscillator: FRB-100

[0092] Connection: RBP-020

[0093] Measurement interval: 6.0 seconds

[0094] Adsorption time: 2.0 seconds

[0095] Then, the maximum value of the logarithmic decay rate in the logarithmic decay rate curve is determined. The maximum value of the logarithmic decay rate is taken as the peak value P2 of the logarithmic decay rate curve before heating.

[0096] In addition, the temperature at which the logarithmic decay rate reaches its maximum value in the logarithmic decay rate curve is determined as the peak temperature of the logarithmic decay rate.

[0097] The measurement was performed more than 5 times, and the peak value and peak temperature were set as the average of their respective values.

[0098] On the other hand, when measuring the peak value P1 of the logarithmic decay rate curve after heating, it is as follows.

[0099] Test pieces measuring 20mm × 60mm were collected from the electromagnetic steel plate with adhesive coating of the test object.

[0100] The test piece was heated to a steel plate surface temperature of 200℃ for 1 minute. After heating, the test piece was cooled to room temperature (25℃).

[0101] Next, similar to the determination of P2, a rigid body oscillator test was performed on the test piece to obtain the logarithmic decay rate curve.

[0102] Then, the maximum value of the logarithmic decay rate in the logarithmic decay rate curve is determined. The maximum value of the logarithmic decay rate is taken as the peak value P1 of the logarithmic decay rate curve after heating at 200℃ for 1 minute.

[0103] [Pencil Hardness]

[0104] The pencil hardness of the adhesive coating is preferably 3H to 4H. By setting it within this range, both hot-pressing adhesion and anti-blocking properties can be achieved.

[0105] Furthermore, the pencil hardness of the adhesive-coated pencil after heating at 200°C for 1 minute is preferably 5H to 6H. By setting it within this range, both adhesive strength and magnetic properties can be considered.

[0106] The hardness of the pencil was determined according to the method of JISK 5600-5-4:1999.

[0107] [Average thickness of adhesive coating]

[0108] The average thickness of the adhesive coating is preferably 1.0 to 6.0 μm, more preferably 1.5 to 3.0 μm.

[0109] Even when the film is thinned in such a way that the average thickness of the adhesive coating is within the range described above, the adhesive strength and magnetic properties of the electromagnetic steel sheet with adhesive coating disclosed herein are excellent.

[0110] The method for determining the average thickness of the adhesive coating is as follows.

[0111] The electromagnetic steel plate with adhesive coating of the test object is cut along the thickness direction to obtain a test piece with the cut surface as the observation surface.

[0112] 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 arithmetic mean of the thicknesses at the three locations was then calculated to determine the average thickness of the adhesive coating.

[0113] [Components of the adhesive coating]

[0114] The adhesive coating comprises crosslinked thermoplastic resin A and thermoplastic resin B other than crosslinked thermoplastic resin A.

[0115] That is, the adhesive coating is cured by heating and pressurizing, at least the crosslinking progress of the crosslinked thermoplastic resin A, and exhibits insulating properties with adhesive ability.

[0116] - Crosslinked thermoplastic resin A -

[0117] Crosslinked thermoplastic resin A is a thermoplastic resin with crosslinking groups.

[0118] In ensuring heat resistance, 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 5g per 100g of water (e.g., less than 1g).

[0119] The adhesive coating may contain only one type of crosslinked thermoplastic resin A, or it may contain two or more types.

[0120] In crosslinkable thermoplastic resin A, the crosslinking group can be either a self-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. Preferably, the crosslinking group is one that exhibits crosslinking properties upon heating.

[0121] Specifically, crosslinking groups include: N-hydroxymethyl, N-hydroxybutyl, glycidyl, alkoxymethylamide, alkoxysilyl, hydroxyl, phenolic hydroxyl, carboxyl, thiol, amino, etc.

[0122] The crosslinked thermoplastic resin A can be any of the vinyl-based and non-vinyl-based thermoplastic resins.

[0123] Examples of non-vinyl thermoplastic resins include polyester resin, polyurethane resin, polyamide resin, and phenoxy resin.

[0124] 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.

[0125] Here, "styrene monomer" refers to a monomer having a styrene skeleton (a structure in which one of the six hydrogen atoms in benzene is replaced by a vinyl group).

[0126] Furthermore, "styrene-based resin" refers to a resin in which the proportion of structural units derived from methylstyrene monomers is 50% or more by mass relative to all structural units.

[0127] Additionally, "(meth)acrylic monomers" refers to monomers containing a (meth)acryloyl group.

[0128] Furthermore, "(meth)acrylic monomers" refers to resins in which structural units derived from (meth)acrylic monomers account for more than 50% by mass relative to all structural units.

[0129] "(Meth)acrylic acid" is a term that includes both "acrylic acid" and "methacrylic acid".

[0130] In addition, "olefinic monomers" refers to monomers that have an olefin skeleton consisting of at least 3 carbon atoms and carbon-carbon double bonds.

[0131] Furthermore, "olefin monomer" refers to a resin in which the proportion of structural units derived from olefin monomers is 50% or more by mass relative to all structural units.

[0132] From the perspective of improving adhesive strength and magnetic properties, (meth)acrylic resins and polyester resins are preferred as crosslinking thermoplastic resin A.

[0133] - Content of cross-linked thermoplastic resin A -

[0134] Compared to adhesive coating, the content of crosslinked thermoplastic resin A is preferably 70% to 97% by mass, more preferably 75% to 95% by mass, and even more preferably 80% to 93% by mass.

[0135] -Thermoplastic Resin B-

[0136] Thermoplastic resin B is a thermoplastic resin other than cross-linked thermoplastic resin A.

[0137] Regarding ensuring coatability, thermoplastic resin B is preferably a water-soluble resin. Here, a water-soluble resin is defined as a resin whose solubility in water at 25°C is 5g or more per 100g of water.

[0138] The adhesive coating may contain only one thermoplastic resin B, or it may contain two or more.

[0139] Thermoplastic resin B can be any of vinyl-based thermoplastic resins and non-vinyl-based thermoplastic resins.

[0140] Examples of non-vinyl thermoplastic resins include non-vinyl resins exemplified in cross-linked thermoplastic resin A.

[0141] Examples of vinyl-based thermoplastic resins include vinyl-based resins exemplified in crosslinked thermoplastic resin A.

[0142] From the viewpoint of improving adhesive strength and magnetic properties, (meth)acrylic resins and polyester resins are preferred as thermoplastic resin B.

[0143] 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 adhesive strength and magnetic properties, a non-cross-linked thermoplastic resin is preferred.

[0144] Examples of non-crosslinked thermoplastic resins include vinyl-based and non-vinyl-based thermoplastic resins that do not have crosslinking groups, as exemplified in crosslinked thermoplastic resin A.

[0145] - Content of thermoplastic resin B -

[0146] 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 97 / 3 to 70 / 30 (A:B=97:3 to 70:30), more preferably 95 / 5 to 85 / 15, and even more preferably 95 / 5 to 90 / 10.

[0147] If the mass ratio of crosslinked thermoplastic resin A to thermoplastic resin B is 97 / 3 to 70 / 30, the bonding strength and magnetic properties are both superior.

[0148] -Other ingredients-

[0149] Adhesive coatings may also contain other components (so-called other components) as needed, without compromising their effectiveness.

[0150] In particular, the adhesive coating may also contain a crosslinking agent. Since crosslinking agents affect both adhesive strength and magnetic properties, they are a particularly preferred component.

[0151] Examples of crosslinking agents include thermosetting resins, specifically epoxy resins, phenolic resins, and amino resins (melamine resins, guanidine resins, etc.) and other polymeric crosslinking agents.

[0152] Examples of crosslinking agents include 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.).

[0153] 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.

[0154] Adhesive coatings can contain only one crosslinking agent or two or more.

[0155] -Component Analysis-

[0156] Based on the qualitative analysis of the components contained in the electromagnetic steel sheet with adhesive coating, and 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.

[0157] Analytical samples of electromagnetic steel sheets with adhesive coatings can be collected by cutting out the coated portion using a precision cutter. Alternatively, in the case of a laminated core, samples can be collected using the above method after peeling several electromagnetic steel sheets from the laminated core.

[0158] (Manufacturing method of electromagnetic steel sheet with adhesive coating)

[0159] 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.

[0160] (I) A coating process in which 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; and

[0161] (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 10~90 seconds from the drying temperature to the drying temperature -10°C, thereby forming an adhesive coating on the surface of the electromagnetic steel plate.

[0162] Each process step is explained.

[0163] —Coating process—

[0164] In the coating process, an adhesive coating liquid (hereinafter also referred to as "the coating liquid 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.

[0165] 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 water-containing medium.

[0166] In the coating liquid of this disclosure, crosslinked thermoplastic resin particles A are dispersed in a water-containing medium. Additionally, thermoplastic resin B is dissolved in a water-containing medium.

[0167] By applying the coating liquid and then drying it, an adhesive film containing crosslinked thermoplastic resin A and thermoplastic resin B is obtained.

[0168] In the coating liquid of this disclosure, the mass ratio of crosslinked thermoplastic resin A to thermoplastic resin B is preferably 97 / 3 to 70 / 30. With this formulation, the mass ratio of crosslinked thermoplastic resin A to thermoplastic resin B in the formed adhesive film also becomes 97 / 3 to 70 / 30.

[0169] There is no specific limitation on the type of water used here.

[0170] 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.

[0171] 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.

[0172] The coating liquid disclosed herein may, as needed, contain other components (so-called other components) besides those mentioned above, without impairing its effectiveness.

[0173] Other components include, for example, aqueous media other than water.

[0174] As a water-based medium other than water, examples include water-miscible organic solvents.

[0175] 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.

[0176] In addition, other components include various additives such as chain preservatives, wetting agents, and defoamers.

[0177] The coating solution disclosed herein is obtained, for example, by mixing a dispersion of crosslinked thermoplastic resin particles A and an aqueous solution of thermoplastic resin B.

[0178] As a mixing method, one example is mixing by stirring.

[0179] Stirring can be done using general stirring utensils or stirring devices.

[0180] There is no particular limitation on the stirring temperature, but it is preferably 20°C to 30°C.

[0181] The formation of an adhesive film using the coating liquid of this disclosure can be achieved by the following methods: applying the coating liquid to the surface of an electromagnetic steel sheet by a known coating method such as a roller coater or a spray coater, and then drying the coating film.

[0182] The concentration of solid components in the coating liquid is preferably 5 to 40% by mass, more preferably 10 to 25%.

[0183] —Coating process—

[0184] In the coating process, the electromagnetic steel sheet (coated steel sheet) coated with coating liquid is heated to a drying temperature (maximum temperature reached by the material) of 100~200℃ at a heating rate of less than 6.0℃ / second, and dried by holding it in the temperature range of drying temperature to (drying temperature -10℃) for 10~90 seconds, thereby forming an adhesive coating on the surface of the electromagnetic steel sheet.

[0185] The drying time (the time the material temperature is maintained at the drying temperature -10°C to the drying temperature) is preferably set to 30-90 seconds. The heating rate is the average heating rate calculated based on the time from 50°C to the drying temperature.

[0186] 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.

[0187] If the drying time exceeds 90 seconds, it becomes a disadvantage in terms of productivity.

[0188] 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.

[0189] 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.

[0190] (Layered iron core)

[0191] 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.

[0192] Here, the cured film of the adhesive coating refers to the film that has been cured by the cross-linking process of the cross-linked thermoplastic resin A in the adhesive coating and exhibits adhesive ability.

[0193] Specifically, as a laminated iron core of this disclosure, for example, a stamped electromagnetic steel plate with an adhesive coating of this disclosure can be used to make a stamped component, and the stamped component can be stacked and integrated by heating and pressurizing to obtain a laminated iron core.

[0194] The stacking factor of the laminated iron core disclosed herein is preferably 96~98%.

[0195] When manufacturing using the electromagnetic steel sheet with adhesive coating disclosed herein, high adhesive strength can be obtained even if the adhesive layer is thinned, so the stacking factor can be set to the range mentioned above.

[0196] 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 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.

[0197] 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.

[0198] 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.

[0199] The laminated iron core disclosed herein is manufactured, for example, by a manufacturing method including the following steps.

[0200] (III) The blanking process involves blanking the electromagnetic steel sheet with adhesive coating disclosed herein to obtain a blanked component;

[0201] (IV) Lamination process, wherein multiple sheets of the aforementioned stamped components are laminated to obtain a laminated body; and

[0202] (V) Bonding process: The laminate is heated to a pressure temperature in the temperature range of 200~300°C, and held for 1~60 minutes under a pressure of 0.5~10MPa within the range of the pressure temperature to the pressure temperature -10°C.

[0203] Each process step is explained.

[0204] —Punching process—

[0205] 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.

[0206] —Layering process—

[0207] 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.

[0208] — Bonding process —

[0209] In the bonding process, the laminate is heated to a pressure temperature (the highest temperature reached by the material) in the temperature range of 200~300°C, and held for 1~60 minutes under an applied pressure of 0.5~10 MPa within the range of the pressure temperature to -10°C. This allows the crosslinking of the crosslinked thermoplastic resin A in the adhesive coating to progress, causing the adhesive coating to cure. As a result, the cured adhesive coating exhibits adhesive properties, and the electromagnetic steel sheets are bonded together using the cured adhesive coating to obtain a laminated iron core.

[0210] Electromagnetic steel sheets with adhesive coatings can be bonded together by having the cured films of the sheets facing each other, or by having the cured film of one sheet facing the non-forming surface of the adhesive coating of another sheet.

[0211] When the pressure temperature is below 200℃, the curing is insufficient; when it exceeds 300℃, the resin oxidizes.

[0212] When the applied pressure is less than 0.5 MPa, unbonded areas are easily formed; when it exceeds 10 MPa, strain is generated in the steel plate.

[0213] If the holding time (the time the material temperature is maintained at the pressurized temperature -10°C to the pressurized temperature) is less than 1 minute, curing will be insufficient; if it exceeds 60 minutes, the yield will decrease. In cases with a large number of sheets stacked, the holding time is preferably 5 minutes or more, and more preferably 30 minutes or more, in order to ensure uniform heating.

[0214] (Applications of laminated iron cores)

[0215] 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.

[0216] Example

[0217] 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.

[0218] [Examples 1-8, Comparative Examples 1-9]

[0219] 1. Manufacturing of coating liquid

[0220] A coating solution with a solid content of 40% by mass was prepared by mixing an aqueous dispersion of crosslinked thermoplastic resin A particles, an aqueous solution of thermoplastic resin B, and a crosslinking agent, according to the types and amounts (parts by mass) shown in Table 1.

[0221] The amounts (parts) of crosslinked thermoplastic resin A, thermoplastic resin B, and crosslinking agent in the coating liquid are shown in Table 1.

[0222] In addition, "solid component concentration" refers to the total mass ratio of the aqueous solutions of crosslinked thermoplastic resin A and thermoplastic resin B, as well as the crosslinking agent, in the coating liquid.

[0223] In Examples 5-7, Comparative Examples 2 and 10, coating solutions containing crosslinked thermoplastic resin A, thermoplastic resin B, and a crosslinking agent were obtained.

[0224] In Examples 1-4, 8, and Comparative Examples 3-4, 9, coating solutions without crosslinking agents were obtained.

[0225] In Comparative Example 1, a coating liquid containing no thermoplastic resin B was obtained.

[0226] In Comparative Example 5, a coating liquid containing neither crosslinking thermoplastic resin A nor crosslinking agent was obtained.

[0227] In Comparative Example 6, a coating liquid containing neither thermoplastic resin B nor crosslinking agent was obtained.

[0228] In Comparative Examples 7 and 8, coating solutions without crosslinking thermoplastic resin A were obtained.

[0229] The details of the materials used, as recorded in Table 1, are shown below.

[0230] <Crosslinked thermoplastic resin A>

[0231] Crosslinked acrylic resin (1): Crosslinking group = N-hydroxymethyl; Weight average molecular weight: 180,000

[0232] Crosslinked acrylic resin (2): Crosslinked groups = glycidyl groups; weight-average molecular weight: 150,000

[0233] Crosslinked acrylic resin (3): Crosslinked groups = carboxyl groups; weight-average molecular weight: 300,000

[0234] Crosslinked acrylic resin (4): Crosslinked groups = amino; weight-average molecular weight: 80,000

[0235] Crosslinked polyester (5): Crosslinked groups = hydroxyl groups; weight-average molecular weight: 30,000

[0236] Crosslinked polyester (6): Crosslinked groups = carboxyl groups; weight-average molecular weight: 120,000

[0237] <Thermoplastic Resin B>

[0238] Acrylic resin weight average molecular weight: 50,000

[0239] Polyester resin weight average molecular weight: 160,000

[0240] Polyurethane resin weight-average molecular weight: 20,000

[0241] Phthaloyl resin weight-average molecular weight: 100,000

[0242] Crosslinking agent

[0243] Epoxy resin: Bisphenol A type, weight average molecular weight: 1000~4000

[0244] Phenolic resin: Phenolic varnish type, weight average molecular weight: 3000~5000

[0245] Amino resin: methylated benzoguanidine, weight average molecular weight: 5000~8000

[0246] In Table 1, the units of the values ​​listed in the columns for crosslinked thermoplastic resin A, thermoplastic resin B, and crosslinking agent are expressed as parts by mass. Empty columns in the columns for crosslinked thermoplastic resin A, thermoplastic resin B, and crosslinking agent indicate that materials conforming to that column were not used.

[0247] [Table 1]

[0248]

[0249] 2. Fabrication of electromagnetic steel sheets with adhesive coating

[0250] 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.

[0251] Next, the coating liquid obtained in step 1 is applied to one side of the electromagnetic steel plate, and then heated and dried at the drying temperature, drying time and heating rate shown in Table 1 to form an adhesive film with the thickness shown in Table 1.

[0252] In this way, an electromagnetic steel sheet with an adhesive coating is obtained.

[0253] [evaluate]

[0254] (Logarithmic decay rate curve)

[0255] The following parameters were measured according to the above method: the peak temperature of the logarithmic decay rate curve of the adhesive coating in the electromagnetic steel plate with adhesive coating, as determined by the rigid body oscillator test; the peak value P1 of the logarithmic decay rate curve after heating at 200°C for 1 minute; the peak value P2 of the logarithmic decay rate curve before heating; and the peak ratio of P1 and P2 (P1 / P2).

[0256] (Pencil hardness)

[0257] The pencil hardness of the adhesive coating in the electromagnet with adhesive coating in each example was determined by heating at 200°C for 1 minute and the pencil hardness before heating, in accordance with the method of JISK 5600-5-4:1999.

[0258] (Adhesive strength)

[0259] 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 to form a laminate. The laminate was 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 a laminate sample for adhesive strength testing.

[0260] The shear bond strength was determined as follows, with the steel plate at room temperature (25℃). The sample for bond strength testing was mounted on a tensile testing machine, and the shear bond strength was measured at a tensile speed of 50 mm / min.

[0261] 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.

[0262] If the bond strength is above 6.0 MPa, it is considered to have sufficient bond strength.

[0263] In addition, two 30mm × 60mm single-plate test pieces were cut from the electromagnetic steel plates with adhesive coatings in each example. The laminated samples obtained by overlapping the 30mm × 10mm ends of the two single-plate test pieces with their adhesive coatings facing each other were placed in an atmosphere of 150°C. Under the same conditions as at room temperature, the shear bond strength was measured at a steel plate temperature of 150°C.

[0264] 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℃.

[0265] If the bond strength is above 2.0 MPa, it is considered to have sufficient bond strength.

[0266] (magnetic properties)

[0267] From the example electromagnetic steel sheets with adhesive coatings, cut 55mm × 55mm single-plate test pieces. Then, overlap two single-plate test pieces with their adhesive coatings facing each other. The overlap is then 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 laminated sample.

[0268] The iron loss in the rolling direction and the rolling right angle direction of the obtained laminate sample 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.

[0269] If the iron loss is below 10.9 W / kg, it is judged to have excellent magnetic properties.

[0270] (Appearance)

[0271] Three 5mm square test pieces were cut from the electromagnetic steel sheet with adhesive coating in each example to obtain the test pieces.

[0272] 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.

[0273] Then, evaluate according to the following evaluation criteria, and classify A and B as qualified.

[0274] A: No coating defects such as cracks, fissures, or peeling were found.

[0275] B: The area with coating defects is less than 10%.

[0276] C: The area ratio of coating defects is greater than 10% but less than 30%.

[0277] D: The area ratio of coating defects is over 30%.

[0278] [Table 2]

[0279]

[0280] Based on the above results, it can be seen that in this embodiment, compared with the comparative example, the appearance, bonding strength from room temperature to high temperature, and magnetic properties are all superior.

[0281] Industrial availability

[0282] According to 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. Therefore, it has high industrial applicability.

[0283] Explanation of reference numerals in the attached figures

[0284] 10 Electromagnetic steel sheet with adhesive coating

[0285] 10A Electromagnetic Steel Sheet

[0286] 10B Adhesive Coating

[0287] 10C Adhesive Coating

[0288] 11. Punching components of electromagnetic steel sheets with adhesive coating

[0289] 100-layer laminated iron core

Claims

1. An electromagnetic steel plate with an adhesive coating, comprising: Electromagnetic steel sheet; and An adhesive coating, which is an adhesive coating disposed on at least a portion of one or both sides of the electromagnetic steel plate, comprises a cross-linked thermoplastic resin A and a thermoplastic resin B other than the cross-linked thermoplastic resin A. The peak temperature of the logarithmic decay rate curve in the adhesive coating, as determined by the rigid oscillator test, is 130~150℃. The peak ratio of the peak value P1 of the logarithmic decay rate curve after heating at 200℃ for 1 minute to the peak value P2 of the logarithmic decay rate curve before heating, i.e., P1 / P2, is 0.70~1.

30.

2. The electromagnetic steel plate with adhesive coating as described in claim 1, The value of P2 is 0.07~0.

30.

3. The electromagnetic steel plate with adhesive coating as described in claim 1, The pencil hardness of the adhesive coating before heating is 3H~4H.

4. The electromagnetic steel plate with adhesive coating as described in claim 1, The value of P1 is 0.05~0.

25.

5. The electromagnetic steel plate with adhesive coating as described in claim 1, The hardness of the heated pencil with the adhesive coating is 5H to 6H.

6. The electromagnetic steel sheet with adhesive coating as described in claim 1, The crosslinked thermoplastic resin A is one or more resins selected from the group consisting of (meth)acrylic resins and polyester resins.

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

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

9. A method for manufacturing an electromagnetic steel sheet with an adhesive coating, comprising the following steps: The 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; and 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 of 10-90 seconds from the drying temperature to -10°C to form an adhesive coating on the surface of the electromagnetic steel sheet.

10. The method for manufacturing an electromagnetic steel sheet with an adhesive coating as described in claim 9, In the coating process, the coating liquid for forming the adhesive film includes a crosslinked thermoplastic resin A and a thermoplastic resin B other than the crosslinked thermoplastic resin A, wherein the mass ratio of the crosslinked thermoplastic resin A to the thermoplastic resin B is 97 / 3 to 70 / 30.

11. A method for manufacturing a laminated iron core, comprising the following steps: The 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 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 drying it in a temperature range of 10-90 seconds from the drying temperature to -10°C, thereby forming an adhesive coating on the surface of the electromagnetic steel sheet and obtaining an electromagnetic steel sheet with an adhesive coating. 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. as well as In the bonding process, the laminate is heated to a pressure temperature in the range of 200~300℃, and held for 1~60 minutes under a pressure of 0.5~10MPa within the range of the pressure temperature to the pressure temperature -10℃.

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