Electromagnetic steel sheet and its laminate

Abstract

An object of the present invention is to provide an electromagnetic steel sheet having a coating layer that allows the electromagnetic steel sheets to be bonded (fastened) without using existing fastening methods such as welding, clamping, or interlocking, and a laminate thereof. The electromagnetic steel sheet of the present invention includes an electromagnetic steel sheet and a polyurethane coating layer located on the electromagnetic steel sheet, and is characterized in that the polyurethane coating layer has a rebound resilience of 5 to 30%.

Description

Technical Field

[0001] Relates to electromagnetic steel sheets and laminates thereof.

Background Art

[0002] Non-oriented electromagnetic steel sheets are steel sheets with uniform magnetic properties in all directions on the rolled plate, and are widely used in cores of motors, generators, electric motors, small transformers, etc.

[0003] Electromagnetic steel sheets are classified into two forms: those that must undergo stress relief annealing (SRA) after punching to improve magnetic properties, and those that omit stress relief annealing when the cost loss due to heat treatment is greater than the magnetic property effect due to stress relief annealing.

[0004] The insulating coating is a coating applied in the finishing manufacturing process of laminates such as cores of motors, generators, electric motors, small transformers, etc., and usually requires electrical properties to suppress the generation of eddy currents. In addition, continuous punching processability, anti-adhesion property, and surface adhesion property are also required. Continuous punching processability means the ability to suppress the wear of the die when punching into a predetermined shape and then laminating a large number to form a core. The anti-adhesion property means the ability not to adhere between the core steel sheets after the stress relief annealing process of removing the processing stress of the steel sheet and restoring the magnetic properties. In addition to such basic properties, excellent coating workability of the coating solution and solution stability that can be used for a long time after blending are also required. Such an insulating coating enables the production of electromagnetic steel sheet laminates by using separate fastening methods such as welding, clamping, and interlocking.

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide an electromagnetic steel sheet and a laminate thereof having a coating layer capable of adhering (fastening) electromagnetic steel sheets without using existing fastening methods such as welding, clamping, and interlocking.

Means for Solving the Problem

[0006] An electromagnetic steel sheet according to an embodiment of the present invention includes an electromagnetic steel sheet and a polyurethane coating layer located on the electromagnetic steel sheet, and is characterized in that the rebound resilience of the polyurethane coating layer is 5 to 30%.

[0007] The polyurethane coating layer has a tensile strength of 50 to 70 MPa.

[0008] The polyurethane coating layer has an elongation rate of 150 to 250%.

[0009] The polyurethane coating layer contains organic particles, inorganic particles, or a combination thereof.

[0010] The total of organic particles, inorganic particles, or a combination thereof in the polyurethane coating layer is more than 0 and 20% by weight or less based on 100% by weight of the entire coating layer.

[0011] The polyurethane coating layer contains an adhesive resin and a bonding additive, and the adhesive resin is a polyurethane formed by the reaction of a diisocyanate monomer and a polyol.

[0012] The bonding additive is one or more selected from the group consisting of a coupling agent, a wetting agent, a curing agent, and a curing catalyst.

[0013] The diisocyanate monomer includes an aromatic diisocyanate monomer, an aliphatic diisocyanate monomer, or a mixture thereof.

[0014] The aromatic diisocyanate monomer is represented by the following Chemical Formula 1, Chemical Formula 2, or a combination thereof.

[0015]

Chemical Formula

[0016]

Chemical formula

[0017] In the chemical formula 1, R 1 ~R 10 are, independently of each other, hydrogen, deuterium, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C5-C20 heteroaryl group, or an isocyanate group, R 1 ~R 5 any one of which is an isocyanate, R 6 ~R 10 any one of which is an isocyanate, R 3 and R 8 are excluded when they are both isocyanates at the same time, L is a substituted or unsubstituted C1-C10 alkylene group, a substituted or unsubstituted C2-C10 alkynylene group, a substituted or unsubstituted C6-C20 arylene group, or a substituted or unsubstituted C5-C20 heteroarylene group, n is any integer from 1 to 10,

[0018] In the chemical formula 2, R 11 ~R 16 are, independently of each other, hydrogen, deuterium, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C5-C20 heteroaryl group, an isocyanate group, or a substituted or unsubstituted C1-C10 alkyl isocyanate group, R 11 ~R 16 at least two of which are isocyanates, or substituted or unsubstituted C1-C10 alkyl isocyanates.

[0019] The aliphatic diisocyanate monomer is represented by the following Chemical Formula 3.

[0020] [Chemical Formula] In Chemical Formula 3, R is a substituted or unsubstituted C1-C10 alkyl group or a substituted or unsubstituted C3-C12 cycloalkyl group.

[0021] The electromagnetic steel sheet laminate according to one embodiment of the present invention includes a plurality of electromagnetic steel sheets and a polyurethane coating layer positioned between the electromagnetic steel sheets, and the resilience modulus of the polyurethane coating layer is 5-30%.

[0022] The polyurethane coating layer has a tensile strength of 50-70 MPa.

[0023] The polyurethane coating layer has an elongation at break of 150-250%.

[0024] The polyurethane coating layer contains organic particles, inorganic particles, or a combination thereof.

[0025] The total of organic particles, inorganic particles, or a combination thereof in the polyurethane coating layer is more than 0 and 20% by weight or less based on 100% by weight of the entire coating layer. [Advantages of the Invention]

[0026] According to the present invention, electromagnetic steel sheets can be adhered without using existing fastening methods such as welding, clamping, and interlocking. According to the present invention, an electromagnetic steel sheet adhesive coating composition excellent in noise characteristics, vibration characteristics, tensile strength, coating adhesion, peeling characteristics, etc. can be provided. [Brief Description of the Drawings]

[0027]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0028] Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, and the present invention is not limited thereby. The present invention is defined only by the scope of the claims described below.

[0029] The present invention aims to provide a bonding composition for electromagnetic steel sheets. The adhesive coating composition described in the present invention is also a term used to indicate the bonding composition. Further, the bonding composition of the present invention is a composition capable of bonding the surfaces of two or more steel sheets, and its use is not particularly limited. For example, it may be a self-bonding composition for electromagnetic steel sheets for providing self-bonding of electromagnetic steel sheets.

[0030] In one embodiment of the present invention, an electromagnetic steel sheet and its laminate are provided. An electromagnetic steel sheet laminate according to an embodiment of the present invention includes a plurality of electromagnetic steel sheets and a polyurethane coating layer positioned between the plurality of electromagnetic steel sheets. FIG. 1 shows a schematic view of an electromagnetic steel sheet laminate according to an embodiment of the present invention. As shown in FIG. 1, a plurality of electromagnetic steel sheets are laminated.

[0031] FIG. 2 shows a schematic view of a cross section of an electromagnetic steel sheet laminate according to an embodiment of the present invention. As shown in FIG. 2, an electromagnetic steel sheet laminate 100 according to an embodiment of the present invention includes a plurality of electromagnetic steel sheets 10 and a polyurethane coating layer 30 positioned between the plurality of electromagnetic steel sheets.

[0032] An electromagnetic steel sheet laminate according to an embodiment of the present invention may be a laminate in which different electromagnetic steel sheets are heat-sealed by simply forming a polymer adhesive layer using the above-described adhesive coating composition without using existing methods such as welding, clamping, and interlocking. At this time, since the electromagnetic steel sheet laminate is used to fabricate the motor core by adhesion, physical and thermal shocks are not applied to the steel sheet like welding and interlocking. As a result, when manufacturing the motor, it has excellent motor efficiency. In addition, by adhering the entire single sheet with an adhesive, noise / vibration generated from unadhered parts can be minimized, and the ability to absorb noise can be increased, thereby improving the noise / vibration characteristics.

[0033] As the electromagnetic steel sheet 10, a general non-oriented or oriented electromagnetic steel sheet can be used without limitation. In one embodiment of the present invention, since the main configuration is to form a polyurethane coating layer 30 between a plurality of electromagnetic steel sheets 10 to manufacture the electromagnetic steel sheet laminate 100, a specific description of the electromagnetic steel sheet 10 will be omitted.

[0034] The polyurethane coating layer 30 is formed between a plurality of electromagnetic steel sheets 10 and has a strong adhesive force to the extent that the plurality of electromagnetic steel sheets 10 can be adhered without using existing fastening methods such as welding, clamping, and interlocking. The polyurethane coating layer 30 is formed by coating the surface with an adhesive coating composition, curing it to form an adhesive coating layer, and laminating and heat-sealing this layer to form the polyurethane coating layer 30.

[0035] If a plurality of electromagnetic steel sheets 10 formed with a polyurethane coating layer are laminated and heat-sealed, the resin component in the adhesive coating layer can be heat-sealed to form a polymer adhesive layer. Such a polymer adhesive layer contains an inorganic metal compound as a main component of the organic matter. In the polymer adhesive layer, the inorganic component can be uniformly dispersed in the organic matter to form a fine phase.

[0036] If the laminate is configured to satisfy such elements, a laminate (core) that can satisfy all the various characteristics currently required in the EV market can be obtained. Hereinafter, each element will be specifically described.

[0037] Polyurethane coating layer The polyurethane coating layer of an embodiment of the present invention can include an adhesive resin and a bonding additive. At this time, the adhesive resin may be a polyurethane formed by the reaction of a diisocyanate monomer and a polyol.

[0038] The diisocyanate monomer can include an aromatic diisocyanate monomer, an aliphatic diisocyanate monomer, or a mixture thereof. The aromatic diisocyanate monomer may be a monomer of the following Chemical Formula 1, 2, or a combination thereof.

[0039]

Chemical formula

[0040]

Chemical formula

[0041] In the Chemical Formula 1, R 1 ~R 10 are each independently hydrogen, deuterium, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C5-C20 heteroaryl group, or an isocyanate group, R 1 ~R 5 any one of which is isocyanate, and R 6 ~R 10 any one of which is isocyanate, L is a substituted or unsubstituted C1-C10 alkylene group, a substituted or unsubstituted C2-C10 alkynylene group, a substituted or unsubstituted C6-C20 arylene group, or a substituted or unsubstituted C5-C20 heteroarylene group, n is any integer from 1 to 10,

[0042] In the Chemical Formula 2, R 11~R 16 is, independently of one another, hydrogen, deuterium, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C5-C20 heteroaryl group, an isocyanate group, or a substituted or unsubstituted C1-C10 alkyl isocyanate group, R 11 ~R 16 At least two of which are isocyanate, or a substituted or unsubstituted C1-C10 alkyl isocyanate.

[0043] The monomer represented by the above Chemical Formula 1 is such that any one of R 1 ~R 5 is isocyanate, and any one of R 6 ~R 10 is isocyanate, and the case where R 3 and R 8 are simultaneously isocyanate is excluded, and the case where R 1 and R 10 are simultaneously isocyanate is further excluded.

[0044] The monomer represented by the above Chemical Formula 1 is such that any one of R 1 ~R 5 is isocyanate, and any one of R 6 ~R 10 is isocyanate, and the case where any one of R 1 ~R 5 and any one of R 6 ~R 10 are simultaneously isocyanate symmetrically about L can be further excluded.

[0045] Specifically, the aromatic diisocyanate monomer may be a monomer of the following Chemical Formula 3, 4, or a combination thereof.

[0046]

Chemical Formula

[0047]

Chem.

[0048] More specifically, as the aromatic isocyanate monomer, one or more selected from the group consisting of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, 2,2'-methylenediphenyl diisocyanate, 2,4'-methylenediphenyl diisocyanate, 4,4'-methylenediphenyl diisocyanate, and m-xylene diisocyanate can be used.

[0049] The aliphatic diisocyanate monomer may be a monomer represented by the following chemical formula 5.

[0050]

Chem.

[0051] The aliphatic isocyanate monomer includes one or more selected from the group consisting of hexamethylene diisocyanate (HDI), 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and hydrogenated xylene diisocyanate.

[0052] The polyurethane can contain 50 parts by weight or less of the aliphatic diisocyanate monomer with respect to 100 parts by weight in total of the diisocyanate monomers used during polymerization.

[0053] The polyol may be a polyol represented by Chemical Formula 6.

[0054] [Chemical Formula] In Chemical Formula 6, R' may be a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C5-C20 heteroaryl group.

[0055] The polyol may have a number average molecular weight of 400 to 1000 g / mol. Further, the polyol may be poly(propylene glycol).

[0056] The bonding additive may be one or more selected from the group consisting of a coupling agent, a wetting agent, a curing agent, and a curing catalyst.

[0057] The bonding coating layer can contain 0.5 parts by weight or more and 5 parts by weight or less of a coupling agent with respect to 100 parts by weight of the polyurethane resin, and the coupling agent can contain an aminosilane coupling agent. Specifically, the aminosilane coupling agent may be 3-aminopropyl trimethoxysilane. Specifically, the bonding coating layer can contain 0.5 parts by weight or more to 3 parts by weight or less of a coupling agent with respect to 100 parts by weight of the polyurethane resin.

[0058] When forming the bonding coating layer, if the aminosilane is not added or is added in an excessively small amount, the effect of improving the adhesion at the interface between the base iron and the bonding layer cannot be expected, and there may be problems such as poor peel adhesion and ATF resistance characteristics. On the other hand, if the aminosilane is added excessively, agglomeration occurs in the bonding layer, deteriorating mechanical properties such as tensile strength and elongation, and thus there may be a problem that the adhesion between the base iron and the bonding layer is not improved. Therefore, preferably, the content of the aminosilane in the bonding coating layer for the electromagnetic steel sheet is controlled within the above range.

[0059] The bonding coating layer can further contain other components that can be used in the bonding composition in addition to the adhesive polymer resin that is polyurethane and the aminosilane.

[0060] The other components are not limited as long as they are those used in a general bonding coating layer. For example, they include wetting agents, curing agents, curing catalysts, etc.

[0061] Specifically, as the wetting agent, silicone-based wetting agents are included. As an example of the silicone-based wetting additive, it may be polyether-modified polydimethylsiloxane. The wetting agent is added to the bonding coating layer to strengthen the interfacial adhesion force between the electromagnetic steel sheet and the bonding layer.

[0062] Specifically, as the curing agent, it can include aliphatic amine-based, aromatic amine-based, aminoamine-based, or imidazole-based. More specifically, dicyandiamide-based curing agents are included.

[0063] Specifically, as the curing catalyst, imidazole-based curing catalysts are included.

[0064] The bonding coating layer 200 can further contain 0.50 to 2.50 parts by weight of the curing agent with respect to 100 parts by weight of the polyurethane resin. Specifically, it can further contain 0.90 to 1.10 parts by weight of the curing agent. The curing agent plays a role in adjusting the reactivity of the bonding coating layer surface. When the content of the curing agent is excessively low, the curing reaction of the bonding layer may decrease, and there may be a problem of poor stickiness on the bonding layer surface. Conversely, when the curing agent is added excessively, the fastening force may decrease after low-temperature fusion.

[0065] The bonding coating layer can further contain 0.05 to 0.50 parts by weight of the wetting agent with respect to 100 parts by weight of the polyurethane resin. Specifically, it can further contain 0.09 to 0.11 parts by weight of the wetting agent.

[0066] The bonding coating layer can further contain 0.10 to 1.00 parts by weight of the curing catalyst with respect to 100 parts by weight of the polyurethane resin. Specifically, it can further contain 0.40 to 0.60 parts by weight of the curing catalyst.

[0067] Rebound resilience of the polyurethane coating layer The rebound resilience rate of the adhesive coating layer of the bonding product is 5% or more and 30% or less. Considering the change in the rebound resilience rate in the high-temperature driving environment of the bonding product, it is preferably 5% or more and 25% or less. More specifically, it may be 7 to 25%, or may be 7 to 15%. Products made with adhesives having a rebound resilience rate of less than 5% are excellent in vibration absorption ability, but the ATF characteristics of the motor core are reduced due to the addition of excessive inorganic particles. On the other hand, when the rebound resilience rate exceeds 30%, the vibration absorption ability decreases.

[0068] In order to control the rebound resilience rate, it can be controlled by inorganic particles contained in the soft urethane resin. The soft urethane is formed by the mixing reaction of polyol and aromatic isocyanate. Specifically, it is synthesized with a 60% content ratio of polypropylene glycol and a 40% content ratio of aromatic isocyanate mixed with MDI (Methylene Diphenyl Diisocyanate) alone or TDI (Toluene Diisocyanate).

[0069] Therefore, when the inorganic particles contain 0.1 to 20%, it can have the rebound resilience rate within the above range. The types of inorganic particles used at this time can be carbon black, silica, or a mixture thereof, etc.

[0070] The measurement of the rebound resilience rate indicates the rebound energy generated when a weight in the horizontal position is applied to a test piece in the 90-degree position as a percentage in a Digital manner. The detailed measurement standard is measured according to KS M ISO4662.

[0071] Maximum tensile strength and elongation In order to measure the mechanical physical properties of the synthesized polyurethane polymer, it was poured onto release paper, coated to a uniform thickness using an applicator, and then dried in a vacuum oven at 100 °C for 24 hours to produce a dry film. The maximum tensile strength and elongation of the film were measured at a speed of 50 mm / min using a universal testing machine in accordance with ASTM D-1708 standard.

[0072] At this time, the elongation of the urethane layer according to an embodiment of the present invention may be 150 to 250%. More specifically, it may be 110 to 170%.

[0073] When the elongation satisfies this range, there is an advantage that the workability during slitting and punching operations from the core yarn is excellent. When the elongation is 100% or less, powder due to the adhesive layer is generated in the mold during punching, resulting in mold contamination. When the elongation is 250% or more, there is a problem that it extends without being cut by the cutting machine during the slitting operation.

[0074] Also, the tensile strength of the urethane layer according to an embodiment of the present invention may be 50 to 70 MPa. More specifically, it may be 60 to 70 MPa.

[0075] When the tensile strength satisfies this range, there is an advantage that the workability during the production of the motor core by heat fusion from the core yarn is excellent. When the tensile strength is 50 MPa or less, there is a demerit of motor core contamination where the adhesive layer leaks to the outer surface of the core due to the fusion pressure during heat fusion. When the tensile strength is 70 MPa or more, there is a demerit that high pressure is required during heat fusion, resulting in a decrease in workability.

[0076] Noise characteristic evaluation To evaluate the noise characteristics generated per motor core in the drive motor, a ring type motor core was fabricated. A product with an adhesive applied to a non-oriented electromagnetic steel sheet of 0.27 mmt was used to fabricate a ring core with an outer diameter of 128 mm, an inner diameter of 90 mm, and a height of 45 mm by punching and heat fusion. The axial dynamic characteristics of the ring core fabricated in this manner were measured. Generally, in order to grasp the dynamic characteristics (natural frequency, natural mode, damping ratio) of a machine or structure, an external force (Force) is applied, and the transfer function, which is a function for obtaining the dynamic response to this force, is used. This is a function that represents the ratio of the response to the external force (F). When analyzing the response with respect to frequency, particularly when used as the frequency response function (FRF), it becomes the fundamental and most frequently used basic function for dynamic characteristic analysis. The damping property was measured by analyzing the FRF characteristics.

[0077] ATF resistance characteristic evaluation When a drive motor is used in an automobile, a large amount of heat is generated during high-speed and long-time rotation. To cool this, ATF (Automotive Transmission Fluid, a special oil for automatic transmissions) is used. Therefore, in order to ensure the adhesion reliability during long-term use, it is important that the adhesive force of the laminated coil is maintained in a state impregnated with high-temperature ATF. For this reason, the ATF resistance property was evaluated.

[0078] After impregnating the fabricated laminated coil in ATF at a temperature of 150 °C for 500 hours, the shear adhesive force was tested. The shear adhesive force for measuring the ATF resistance property was measured by the shear strength method. The specifications of the test piece for shear strength measurement were prepared based on ISO4587. Two test pieces of 25 × 100 mm were adhered at an area of 12.5 × 25 mm 2 and heat-sealed under the above conditions to prepare a test piece by the shear method.

[0079] After fixing the test piece prepared by the shear method to the upper and lower jigs (JIG) with a constant force, it was measured using a device that measures the tensile force of the laminated sample while pulling at a constant speed. At this time, in the case of the shear method, the measured value was the point where the interface with the minimum adhesive force among the interfaces of the laminated sample dropped off.

[0080] The examples and comparative examples in Table 1 below contain, based on 100 parts by weight of the bonding resin, 0.5 part by weight of a silane coupling agent, 0.1 part by weight of a silicone-based wetting agent, 1 part by weight of a dicyandiamide-based curing agent, and 0.5 part by weight of an imidazole-based curing catalyst.

[0081] The bonding resins of Examples 1 to 4 and Comparative Examples 1 to 2 in Table 1 used, as the polyurethane, a polyurethane obtained by reacting 40% by weight of the 2,4’-MDI (2,4’-methylenediphenyl diisocyanate) monomer with 60% by weight of PPG (poly(propylene glycol) (water molecular weight 425 g / mol)).

[0082] The bonding resins of Examples 5 to 7 used, as the polyurethane, polyurethanes obtained by reacting 40% by weight of 2,4-TDI, 2,2’-MDI, and 4,4’-MDI, respectively, with 60% by weight of PPG. At this time, TDI means toluene diisocyanate.

[0083] The bonding resin of Example 8 used, as the polyurethane, a polyurethane obtained by reacting 60% by weight of PPG with 40% by weight of a monomer mixture of 2,4’-MDI and HDI mixed at a ratio of 8:2. At this time, HDI means hexamethylene diisocyanate.

[0084] The epoxy resins of Comparative Examples 3 and 4 were Bisphenol A Type epoxy resins with a number average molecular weight of 10,000 g / mol and a hydroxyl value of 10 mgKOH / g.

[0085] The bonding resins of Comparative Examples 5 to 8 were mixtures of a polyurethane resin and an epoxy resin at a weight ratio of 50:50. The polyurethane resin used was the same as that used in Example 1 above, and the epoxy resin used was the same as that used in Comparative Example 3.

[0086]

Table 1

[0087] From the above results, it was confirmed that in the case of Examples 1 to 8, the rebound resilience was 5 to 30%, and they were excellent in vibration absorption evaluation characteristics and ATF resistance characteristics. In Comparative Example 1, although a urethane resin was used, in the case of not containing inorganic particles, the rebound resilience was measured to be slightly high at 40%, and it was inferior in elongation, vibration absorption characteristics, and ATF resistance characteristics.

[0088] In Comparative Example 2, although a urethane resin was used, in the case of excessively containing inorganic particles, the rebound resilience was as low as 3%, and as a result, it was inferior in elongation, vibration absorption characteristics, and ATF resistance characteristics.

[0089] In Comparative Examples 3 and 4, in the case of using an epoxy resin alone, the rebound resilience was less than 5% regardless of whether inorganic particles were contained or not, and the characteristics were also inferior.

[0090] In Comparative Examples 5 to 8, in the case of using a mixture of urethane and an epoxy resin, it was confirmed that they were inferior in vibration absorption evaluation.

[0091] As a result, in order to obtain an electromagnetic steel sheet for bonding that is excellent in both vibration absorption evaluation and ATF resistance characteristics, it can be seen that not only the content of inorganic particles in the coating layer needs to be adjusted, but also the bonding resin used must be polyurethane alone.

[0092] The present invention is not limited to the above-described examples, and can be manufactured in various different forms. Those having ordinary knowledge in the technical field to which the present invention pertains will understand that it can be implemented in other specific forms without changing the technical idea and essential features of the present invention. Therefore, it must be understood that the above-described examples are illustrative in all respects and not restrictive.

Claims

1. An electromagnetic steel sheet, and a polyurethane coating layer located on the electromagnetic steel sheet, wherein the rebound resilience of the polyurethane coating layer is 5 to 30%, the polyurethane coating layer contains inorganic particles, and the total of the inorganic particles in the polyurethane coating layer is 0.1 to 20% by weight based on 100% by weight of the entire coating layer. The electromagnetic steel sheet is characterized by this.

2. The electromagnetic steel sheet according to claim 1, wherein the polyurethane coating layer has a tensile strength of 50 to 70 MPa.

3. The electromagnetic steel sheet according to claim 1, wherein the polyurethane coating layer has an elongation at break of 150 to 250%.

4. The polyurethane coating layer contains an adhesive resin and a bonding additive, and the adhesive resin is a polyurethane formed by the reaction of a diisocyanate monomer and a polyol. The electromagnetic steel sheet according to claim 1.

5. The electromagnetic steel sheet according to claim 4, wherein the bonding additive is one or more selected from the group consisting of a coupling agent, a wetting agent, a curing agent, and a curing catalyst.

6. The electromagnetic steel sheet according to claim 4, wherein the diisocyanate monomer includes an aromatic diisocyanate monomer, an aliphatic diisocyanate monomer, or a mixture thereof.

7. The electromagnetic steel sheet according to claim 6, wherein the aromatic diisocyanate monomer is represented by the following Chemical Formula 1, Chemical Formula 2, or a combination thereof. 【Chemical 1】 【Chemical 2】 In the Chemical Formula 1, R １ ~R １０ are, independently of each other, hydrogen, deuterium, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C5-C20 heteroaryl group, or an isocyanate group, R １ ~R ５ Any one of them is an isocyanate, and R ６ ~R １０ Any one of them is an isocyanate, R ３ and R ８ are simultaneously isocyanates is excluded, L is a substituted or unsubstituted C1-C10 alkylene group, a substituted or unsubstituted C2-C10 alkynylene group, a substituted or unsubstituted C6-C20 arylene group, or a substituted or unsubstituted C5-C20 heteroarylene group, n is any integer from 1 to 10, In the Chemical Formula 2, R １１ to R １６ are, independently of one another, hydrogen, deuterium, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C5-C20 heteroaryl group, an isocyanate group, or a substituted or unsubstituted C1-C10 alkyl isocyanate group, and R １１ to R １６ at least two of which are isocyanate, or a substituted or unsubstituted C1-C10 alkyl isocyanate.

8. The electromagnetic steel sheet according to claim 6, wherein the aliphatic diisocyanate monomer is represented by the following Chemical Formula 3. 【Chemical Formula 3】 In the Chemical Formula 3, R is a substituted or unsubstituted C1-C10 alkyl group or a substituted or unsubstituted C3-C12 cycloalkyl group.

9. A plurality of electromagnetic steel sheets, and a polyurethane coating layer located between the electromagnetic steel sheets, wherein the rebound resilience of the polyurethane coating layer is 5 to 30%. The polyurethane coating layer contains inorganic particles, A laminate in which the total of the inorganic particles in the polyurethane coating layer is 0.1 to 20% by weight based on 100% by weight of the entire coating layer. **Claim 10** The laminate according to claim 9, wherein the polyurethane coating layer has a tensile strength of 50 to 70 MPa. **Claim 11** The laminate according to claim 9, wherein the polyurethane coating layer has an elongation rate of 150 to 250%.

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