Adhesive coating composition for electrical steel sheets, electrical steel sheet laminate and method for producing the same

Abstract

The present invention provides an electromagnetic steel sheet laminate having a fusion layer that can bond (fasten) electromagnetic steel sheets together without using existing fastening methods such as welding, clamping, or interlocking. [Solution] The magnetic steel sheet adhesive coating composition of the present invention comprises a polyurethane resin and an inorganic pigment, and the inorganic pigment is contained in an amount of 20 to 150 parts by weight based on 100 parts by weight of the polyurethane resin, and the polyurethane resin is formed by reacting an aromatic diisocyanate monomer represented by the following chemical formula 1 with a polyol. TIFF2025500285000016.tif47128In the above chemical formula 1, R 1 Or R 5 One of the groups is an isocyanate group, and R 6 Or R 10 One of the groups is an isocyanate group, and R 3 and R 8 isocyanate groups at the same time are excluded.

Description

[Technical Field]

[0001] The present invention relates to an adhesive coating composition for magnetic steel sheets, an magnetic steel sheet laminate, and a method for manufacturing the same, and more particularly to an adhesive coating composition for magnetic steel sheets, an magnetic steel sheet laminate, and a method for manufacturing the same, which form a bonding layer that allows magnetic steel sheets to be bonded (fastened) without using existing fastening methods such as welding, clamping, or interlocking. Specifically, one embodiment of the present invention relates to an adhesive coating composition for magnetic steel sheets, an magnetic steel sheet laminate, and a method for manufacturing the same, which improve the adhesive strength and noise suppression properties of the magnetic steel sheet laminate by controlling the components of the bonding layer formed between the magnetic steel sheets. [Background technology]

[0002] Non-oriented electrical steel sheets are steel sheets that have uniform magnetic properties in all directions on the rolled sheet, and are widely used in motors, generator cores, electric motors, small transformers, etc. Electrical steel sheets can be divided into two types: those that require stress relief annealing (SRA) after punching to improve their magnetic properties, and those that do not require stress relief annealing if the cost loss from heat treatment is greater than the magnetic property benefits from stress relief annealing.

[0003] Insulating coatings are formed by coating during the finishing process of laminates such as the iron cores of motors and generators, electric motors, and small transformers. They typically require electrical properties that suppress eddy currents. Other requirements include continuous punching workability, adhesion resistance, and surface adhesion. Continuous punching workability refers to the ability to suppress die wear when laminating multiple sheets after punching into a desired shape to create an iron core. Adhesion resistance refers to the ability to prevent adhesion between steel sheets in an iron core after stress relief annealing, which removes processing stress from the steel sheets and restores their magnetic properties.

[0004] In addition to these basic properties, the coating solution must be easy to apply and stable enough to be used for a long time after mixing. Such an insulating coating can only be manufactured on an electrical steel sheet laminate using a separate fastening method such as welding, clamping, or interlocking. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an electrical steel sheet laminate having a fusion layer formed thereon that can bond (fasten) electrical steel sheets together without using existing fastening methods such as welding, clamping, interlocking, etc. Specifically, the present invention provides an electrical steel sheet adhesive coating composition, an electrical steel sheet laminate, and a method for manufacturing the same that improve the adhesive strength between electrical steel sheets by controlling the components of the fusion layer formed between the electrical steel sheets. [Means for solving the problem]

[0006] The adhesive coating composition for electrical steel sheets of the present invention comprises a polyurethane resin and an inorganic pigment, wherein the inorganic pigment is present in an amount of 20 to 150 parts by weight based on 100 parts by weight of the polyurethane resin, and the polyurethane resin is formed by reacting an aromatic diisocyanate monomer represented by the following Chemical Formula 1 with a polyol: TIFF0007812926000001.tif47128In the above chemical formula 1, R 1 Or R 10 are each independently hydrogen, deuterium, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C5 to C20 heteroaryl group, or an isocyanate group; R 1 Or R 5 one of which is an isocyanate group, and R 6 Or R 10 one of which is an isocyanate group, and R 3 and R 8is an isocyanate group, and L is a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C2 to C10 alkynylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C5 to C20 heteroarylene group; n is any one integer from 1 to 10.

[0007] In formula 1, R 1 Or R 5 one of which is an isocyanate, and R 6 Or R 10 one of which is an isocyanate, and R 3 and R 8 is an isocyanate, R 1 and R 10 It is further preferable to exclude the case where the isocyanate is also an isocyanate. In formula 1, R 1 Or R 5 one of which is an isocyanate, and R 6 Or R 10 one of which is an isocyanate, and R 1 Or R 5 Any one of the following and R 6 Or R 10 It is further preferable to exclude the case where any one of the groups is symmetrical about L and is simultaneously an isocyanate.

[0008] The aromatic diisocyanate monomer represented by Chemical Formula 1 is preferably one represented by Chemical Formula 2 below. TIFF0007812926000002.tif44128In the above chemical formula 2, L is a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C2 to C10 alkynylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C5 to C20 heteroarylene group. The polyol may be a compound represented by the following formula 3: TIFF0007812926000003.tif17128In the above chemical formula 3, R' is a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C5 to C20 heteroaryl group.

[0009] The polyurethane resin preferably contains 30 to 50% by weight of an aromatic diisocyanate monomer and 50 to 70% by weight of a polyol. The inorganic pigment may be one or more selected from the group consisting of barium sulfate (Ba2SO4), titanium dioxide (TiO2), clay (Al2Si2O5(OH)4), calcium carbonate (CaCO3), silica (SiO2), and talc (3MgO·4SiO2·H2O).

[0010] The electrical steel sheet adhesive coating composition of the present invention may further contain one or more members selected from the group consisting of coupling agents, wetting agents, curing agents and curing catalysts. The coupling agent is Polyurethane It may contain 0.2 to 3 parts by weight based on 100 parts by weight of the resin.

[0011] The hardener is Polyurethane It may contain 0.5 to 2 parts by weight based on 100 parts by weight of the resin. The curing catalyst is Polyurethane It is preferable that the content be 0.1 to 1 part by weight based on 100 parts by weight of the resin. The wetting agent is Polyurethane It is preferable that the content be 0.05 to 0.5 parts by weight based on 100 parts by weight of the resin.

[0012] The electrical steel sheet laminate of the present invention comprises a plurality of electrical steel sheets and a bonding layer located between the plurality of electrical steel sheets, wherein the bonding layer comprises a polyurethane resin and an inorganic pigment, the inorganic pigment comprising 20 to 150 parts by weight based on 100 parts by weight of the polyurethane resin, and the polyurethane resin is formed by reacting an aromatic diisocyanate monomer represented by the following chemical formula 1 with a polyol: TIFF0007812926000004.tif47128In the above chemical formula 1, R 1 Or R 10 are each independently hydrogen, deuterium, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C5 to C20 heteroaryl group, or an isocyanate group; R 1 Or R 5 one of which is an isocyanate group, and R 6 Or R 10 one of which is an isocyanate group, and R 3 and R 8 is an isocyanate group, L is a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C2 to C10 alkynylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C5 to C20 heteroarylene group, and n is an integer of 1 to 10.

[0013] The method for manufacturing an electrical steel sheet laminate of the present invention includes the steps of applying an adhesive coating composition to one or both sides of an electrical steel sheet, followed by curing the composition to form an adhesive coating layer, and stacking a plurality of electrical steel sheets with the adhesive coating layers formed thereon and heat-fusing them to form a fusion layer, wherein the adhesive coating composition includes a polyurethane resin and an inorganic pigment, and the inorganic pigment is present in an amount of 20 to 150 parts by weight based on 100 parts by weight of the polyurethane resin, and the polyurethane resin is formed by reacting an aromatic diisocyanate monomer represented by the following chemical formula 1 with a polyol: TIFF0007812926000005.tif47128In the above chemical formula 1, R 1 Or R 10 are each independently hydrogen, deuterium, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C5 to C20 heteroaryl group, or an isocyanate group; R 1 Or R 5 one of which is an isocyanate group, and R 6 Or R 10 one of which is an isocyanate group, and R 3 and R 8 is an isocyanate group, L is a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C2 to C10 alkynylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C5 to C20 heteroarylene group, and n is an integer of 1 to 10. [Effects of the Invention]

[0014] According to the present invention, the adhesive coating composition for electrical steel sheets of the present invention can control the components of the adhesive layer formed between electrical steel sheets, thereby improving the adhesive strength between the electrical steel sheets. According to the present invention, the adhesive coating composition for electrical steel sheets of the present invention can bond electrical steel sheets without using existing fastening methods such as welding, clamping, or interlocking, and has excellent effects in suppressing noise and vibration of the electrical steel sheet laminate. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a schematic diagram of an electromagnetic steel sheet laminate. [Figure 2] 1 is a schematic view of a cross section of an electrical steel sheet laminate according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited to these. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Thus, a first part, component, region, layer, or section described below can be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention. The terminology used herein is merely for the purpose of referring to particular embodiments and is not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. As used in the specification, the term "comprising" refers to the inclusion of certain features, regions, integers, steps, operations, elements, and / or components, and does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components. When we refer to an item as being "on" or "above" another item, it means that it is immediately on or above the other item, or there may be other items in between. In contrast, when we refer to an item as being "directly on top of" another item, there are no other items in between.

[0017] Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention pertains. Terms defined in commonly used dictionaries are additionally interpreted as having a meaning consistent with the relevant technical literature and the currently disclosed content, and are not interpreted in an ideal or very formal sense unless otherwise defined. Unless otherwise defined, the term "substituted" used herein means that at least one hydrogen atom of a compound is substituted with a C1 to C30 alkyl group, a C1 to C10 alkoxy group, a silane group, an alkylsilane group, an alkoxysilane group, or an ethyleneoxyl group. As used herein, "hetero" means an atom selected from the group consisting of N, O, S and P, unless otherwise defined. The alkyl group may be a C1 to C20 alkyl group, specifically a C1 to C6 lower alkyl group, a C7 to C10 middle alkyl group, or a C11 to C20 higher alkyl group. For example, a C1 to C4 alkyl group means that there are 1 to 4 carbon atoms in the alkyl chain, and indicates that it is selected from the group consisting of methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and t-butyl.

[0018] Typical alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily understand and practice the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments set forth herein.

[0019] The adhesive coating composition for electrical steel sheets of the present invention includes a polyurethane resin and an inorganic pigment, and the inorganic pigment is present in an amount of 20 to 150 parts by weight based on 100 parts by weight of the polyurethane resin. The polyurethane resin may be formed by reacting an aromatic diisocyanate monomer represented by the following Chemical Formula 1 with a polyol. TIFF0007812926000006.tif47128 Chemical formula 1, R 1 Or R 10 are each independently hydrogen, deuterium, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C5 to C20 heteroaryl group, or an isocyanate group; R 1 Or R 5 one of which is an isocyanate group, and R 6 Or R 10one of which is an isocyanate group, and R 3 and R 8 is an isocyanate group, L is a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C2 to C10 alkynylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C5 to C20 heteroarylene group, and n is an integer of 1 to 10.

[0020] In one embodiment of the present invention, the inorganic pigment may be included in an amount of 20 to 150 parts by weight based on 100 parts by weight of polyurethane resin. If the inorganic pigment is included too much, the adhesive layer may become too hard, resulting in poor peel adhesion, while if the polyurethane resin is included too little, the adhesive layer may become too soft, resulting in poor interlayer insulation properties. In formula 1, R 1 Or R 5 one of which is an isocyanate, and R 6 Or R 10 one of which is an isocyanate, and R 3 and R 8 is an isocyanate, R 1 and R 10 It is further preferable to exclude the case where the isocyanate is also an isocyanate.

[0021] In formula 1, R 1 Or R 5 one of which is an isocyanate, and R 6 Or R 10 one of which is an isocyanate, and R 1 Or R 5 Any one of the following and R 6 Or R 10 It is further preferable to exclude the case where any one of the groups is symmetrical about L and is simultaneously an isocyanate. In Chemical Formula 1, when isocyanate is bonded at positions symmetrical about L, the produced electrical steel sheet laminate has poor paint adhesion, peel adhesion strength, or ATF resistance, and cannot be used for self-bonding. The aromatic diisocyanate monomer represented by the above chemical formula 1 is represented by the following chemical formula 2. TIFF0007812926000007.tif44128 Chemical formula 2, L is a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C2 to C10 alkynylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C5 to C20 heteroarylene group.

[0022] The polyol may be a compound represented by the following formula 3: In Formula 3, R' is a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C5 to C20 heteroaryl group. Specifically, the polyol may be polypropylene glycol. The polyol may have a number average molecular weight of 400 to 1000 g / mol.

[0023] The polyurethane resin may contain 30 to 50 wt% aromatic diisocyanate monomer and 50 to 70 wt% polyol. If the ratio of aromatic diisocyanate monomer is too low, the high-temperature fastening strength of the polyurethane resin may decrease, while if the ratio is too high, the heat-sealing properties may decrease. If the ratio of polyol is too low, the heat-sealing properties may decrease, and if the ratio of polyol is too high, the tacky properties may cause stickiness defects during long-term storage in a coiled state.

[0024] The inorganic pigment may be one or more selected from the group consisting of barium sulfate (Ba2SO4), titanium dioxide (TiO2), clay (Al2Si2O5(OH)4), calcium carbonate (CaCO3), silica (SiO2), and talc (3MgO 4SiO2 HO). Specifically, it may be barium sulfate (Ba2SO4).

[0025] The electrical steel sheet adhesive coating composition of the present invention may further comprise one or more selected from the group consisting of coupling agents, wetting agents, curing agents and curing catalysts. The magnetic steel sheet adhesive coating composition may further include a coupling agent to strengthen the interfacial adhesion between the magnetic steel sheet 10 and the adhesive layer 20. The coupling agent may include a silane coupling agent, more specifically, one or more of a vinyl-based silane coupling agent and a methacryloxy-based silane coupling agent. Examples of vinyl-based silane coupling agents include vinyl trimethoxy silane and vinyl triethoxy silane. Examples of methacryloxy-based silane coupling agents include 3-methacryloxypropyl methyldimethoxysilane, 3-methacryloxpropyl trimethoxysilane, 3-methacryloxypropyl methyldiethoxysilane, and 3-methacryloxpropyl triethoxysilane.

[0026] The adhesive coating composition for magnetic steel sheets of the present invention may further include a silicon-based wetting agent in the adhesive coating composition to strengthen the interfacial adhesion between the magnetic steel sheet 10 and the adhesive layer 20. An example of a silicon-based wetting additive is polyether-modified polydimethylsiloxane. The wetting agent may be added to the bonding composition for magnetic steel sheets to strengthen the interfacial adhesion between the magnetic steel sheet and the adhesive layer.

[0027] The electrical steel sheet adhesive coating composition of the present invention may further include a curing agent to adjust the reactivity of the adhesive coating layer surface. The curing agent may include an aliphatic amine, aromatic amine, aminoamine, or imidazole curing agent. More specifically, a dicyandiamide curing agent may be included. The electrical steel sheet adhesive coating composition of the present invention may further contain a curing catalyst to prevent stickiness caused by uncured coating due to a rapid curing reaction during coil coating. The curing catalyst may include an imidazole-based curing catalyst.

[0028] The coupling agent of the electrical steel sheet adhesive coating composition is Polyurethane It is recommended that the amount of coupling agent be 0.2 to 3 parts by weight based on 100 parts by weight of resin. Specifically, it can be 0.2 to 1 part by weight. If the amount of coupling agent is too small, the effect of strengthening the interfacial adhesion between the electrical steel sheet and the adhesive layer may not be sufficient. If the amount of coupling agent is too large, there is a risk of precipitates forming in the adhesive coating composition due to reactions between the coupling agents. The hardener of the electrical steel sheet adhesive coating composition is PolyurethaneIt is recommended that the curing agent be included in an amount of 0.5 to 2 parts by weight based on 100 parts by weight of resin. Specifically, it can be included in an amount of 0.8 to 1.2 parts by weight. The curing agent controls the reactivity of the adhesive coating layer surface. If the curing agent content is too low, the curing reaction of the adhesive layer may be slowed, resulting in a problem of poor stickiness of the adhesive layer surface. Conversely, if the curing agent content is too high, the fastening strength after low-temperature fusion may be poor.

[0029] The curing catalyst for the magnetic steel sheet adhesive coating composition is Polyurethane It is preferable that the curing catalyst content be 0.1 to 1 part by weight based on 100 parts by weight of the resin. Specifically, it can be 0.3 to 0.8 parts by weight. If the curing catalyst content is too high, there is a risk of a problem of poor fastening strength after fusion due to an over-curing reaction, and if the curing catalyst content is too low, there is a risk of a problem of the surface of the fusion layer becoming sticky due to insufficient curing. The wetting agent of the electrical steel sheet adhesive coating composition is Polyurethane The wetting agent may be present in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the resin. Specifically, the wetting agent may be present in an amount of 0.05 to 0.15 parts by weight. If the wetting agent content is too high, excessive foaming may occur in the coating solution, resulting in coating layer defects. If the wetting agent content is too low, the coating layer may have poor wettability, resulting in coating surface defects.

[0030] In addition to the aforementioned components, the adhesive coating composition may contain a solvent to facilitate application and to disperse the components uniformly. The solvent may include water, alcohol, etc. The solvent may be Polyurethane It is preferable that the content be 1 to 20 parts by weight per 100 parts by weight of the resin.

[0031] In one embodiment of the present invention, an electrical steel sheet lamination is provided. The electrical steel sheet laminate of the present invention includes a plurality of electrical steel sheets and a bonding layer located between the plurality of electrical steel sheets. Fig. 1 shows a schematic diagram of the electrical steel sheet laminate of the present invention. As shown in Fig. 1, the configuration is such that a plurality of electrical steel sheets are laminated.

[0032] Fig. 2 shows a schematic cross-sectional view of an electrical steel sheet laminate of the present invention. As shown in Fig. 2, an electrical steel sheet laminate 100 of the present invention includes a plurality of electrical steel sheets 10 and a bonding layer 20 located between the plurality of electrical steel sheets. The electrical steel sheet laminate of the present invention is preferably a laminate in which different electrical steel sheets are heat-fused together by simply forming a fusion layer using the adhesive coating composition described above, without using existing methods such as welding, clamping, or interlocking. In this case, the laminate of electrical steel sheets has the properties of excellent high-temperature adhesiveness and high-temperature oil resistance even after heat fusion. Each component will be described in detail below.

[0033] The electrical steel sheet 10 may be a general non-oriented or oriented electrical steel sheet without any restrictions. In one embodiment of the present invention, the main configuration is to form the bonding layers 20 between a plurality of magnetic steel sheets 10 to manufacture the magnetic steel sheet laminate 100, so a detailed description of the magnetic steel sheets 10 will be omitted. The adhesive layer 20 is formed between the plurality of electromagnetic steel sheets 10, and has such a strong adhesive force that the plurality of electromagnetic steel sheets 10 can be bonded together without using existing fastening methods such as welding, clamping, or interlocking.

[0034] The adhesive layer 20 is formed by coating the surface with an adhesive coating composition, curing it to form an adhesive coating layer, stacking these, and heat-sealing them to form the adhesive layer 20. When multiple magnetic steel sheets 10 with adhesive coating layers formed thereon are stacked and heat-sealed, the resin component in the adhesive coating layer is heat-sealed to form the adhesive layer.

[0035] The fusing layer 20 of the present invention contains a polyurethane resin and an inorganic pigment. The polyurethane resin and inorganic pigment have been described in detail above with respect to the adhesive coating composition, so a repeated description will be omitted. The polyurethane resin and inorganic pigment remain intact during the fusing layer formation process. The coupling agent, curing agent, curing catalyst, and wetting additive also remain, and their content ranges may be the same as those in the adhesive coating composition. The coupling agent, curing agent, curing catalyst, and wetting additive have been described in detail above with respect to the adhesive coating composition, so a repeated description will be omitted. Therefore, the fusion layer is Polyurethane It preferably contains 100 parts by weight of resin, 0.5 parts by weight of silane coupling agent, 0.1 parts by weight of silicon-based wetting agent, 1 part by weight of dicyandiamide-based curing agent, and 0.5 parts by weight of imidazole-based curing catalyst.

[0036] The thickness of the adhesive layer 20 is preferably 5 μm to 20 μm. If the adhesive layer is too thin, the adhesive strength may decrease rapidly, while if it is too thick, defects due to stickiness may become a problem after coating and winding. More specifically, the thickness of the adhesive layer 20 is preferably 7 μm to 15 μm.

[0037] A method for manufacturing an electrical steel sheet laminate according to one embodiment of the present invention includes the steps of applying an adhesive coating composition to one or both sides of an electrical steel sheet, followed by curing the composition to form an adhesive coating layer, and stacking a plurality of electrical steel sheets with the adhesive coating layers formed thereon, and heat-fusing the stacked sheets to form a fusion layer. Each step will be described in detail below.

[0038] First, an adhesive coating composition is prepared. The adhesive coating composition has been described above, so a duplicated description will be omitted. The adhesive coating composition is then coated on the surface of the electrical steel sheet and cured to form an adhesive coating layer, which may be performed at a temperature of 150 to 250°C to cure the adhesive coating composition. A plurality of magnetic steel sheets with adhesive coating layers formed thereon are stacked and heat-sealed to form the adhesive layer 20. Through the heat-sealing step, the polymer components in the adhesive coating layer are heat-sealed to form the adhesive layer.

[0039] The heat-sealing step can be performed at a temperature of 150 to 250°C, under a pressure of 0.05 to 5.0 MPa, and for a pressurizing period of 0.1 to 120 minutes. These conditions can be satisfied independently, or two or more conditions can be satisfied simultaneously. By adjusting the temperature, pressure, and time conditions in the heat-sealing step, the electrical steel sheets can be densely heat-sealed without any gaps or organic phases between them. The heat-sealing step includes a temperature-raising step and a fusion step, and the temperature-raising rate in the temperature-raising step is preferably 10° C. / min to 1000° C. / min. While the present invention may be embodied in many different forms, it is to be understood that the invention is not limited to the embodiments set forth herein.

[0040] Experimental Example 1 A non-oriented electrical steel sheet (80 × 250 mm, 0.35 mm thick) was prepared as a blank specimen. The adhesive coating solution was applied to the top and bottom of each blank specimen using a bar coater and a roll coater to a uniform thickness, cured at a plate temperature of 200°C for 20 seconds, and then slowly cooled in air to form an adhesive coating layer. The adhesive coating solutions used contained 100 parts by weight of polyurethane resin, various amounts of barium sulfate (Ba2SO4), 0.5 parts by weight of silane coupling agent, 0.1 parts by weight of silicone-based wetting agent, 1 part by weight of dicyandiamide-based curing agent, and 0.5 parts by weight of imidazole-based curing catalyst. The polyurethane resin was prepared by reacting 40% by weight of 2,4-methylenediphenyl diisocyanate monomer with 60% by weight of polypropylene glycol with a water molecular weight of 425 g / mol based on the total weight of the polyurethane resin. The content ratios of the polyurethane resin and barium sulfate (Ba2SO4), as well as the types and content ratios of the isocyanate monomer and polyol used, are shown in Table 1 below. In addition to the polyurethane resin, the solutions contained 0.5 parts by weight of silane coupling agent, 0.1 parts by weight of silicone-based wetting agent, 1 part by weight of dicyandiamide-based curing agent, and 0.5 parts by weight of imidazole-based curing catalyst based on 100 parts by weight of polyurethane resin.

[0041] In Table 1, MDI means methylene diphenyl diisocyanate, TDI means toluene diisocyanate, and PPG means polypropylene glycol (water molecular weight 425 g / mol). The adhesive coating-coated magnetic steel sheets were stacked to a height of 20 mm and then heat-sealed at 160°C for 10 minutes under a pressure of 1.0 MPa to produce a magnetic steel sheet laminating agent. The thickness of the heat-sealed layer was approximately 10 μm. The heat-sealed laminates were evaluated based on the ratio of polyurethane resin to barium sulfate in the coating composition and the type of aromatic diisocyanate monomer used. Specifically, the coating adhesion, peel strength (T-peel, N / mm), ATF resistance, and interlayer insulation properties were evaluated and the results are shown in Table 1 below.

[0042] The methods for measuring each property are as follows. Coating adhesion measurement method: The coating adhesion measurement specimen was prepared based on ISO 1519. The coated specimen was prepared into a 30 x 300 mm sample and bent 180 degrees onto a 10 mm diameter iron cylinder. Tape was then attached to the bent portion and the coating layer was visually inspected for peeling. If peeling occurred, it was evaluated as NG, and if no peeling occurred, it was evaluated as OK. Peel adhesion strength (T-peel, N / mm): The specimen standard for measuring the peel method (T-Peel off) was prepared according to ISO 11339. Two 25 x 200 mm specimens were placed on a 25 x 150 mm 2 After bonding over an area of ​​100 mm, the unbonded area was bent 90° to prepare a T-shaped tensile specimen. The specimen prepared using the T-peel off method was fixed to upper and lower jigs with a constant force and pulled at a constant speed, measuring the tensile strength of the laminated sample using a device that measures the strength of the laminated sample. In the case of the shear method, the measured value was the point at which the interface with the minimum adhesive strength between the laminated sample interfaces fell off. The temperature of the specimen was maintained at 60°C using a heating device, and the adhesive strength was measured.

[0043] Evaluation method for ATF resistance: When a drive motor is used in an automobile, a lot of heat is generated when it rotates at high speed for a long time, and ATF (Automotive Transmission Fluid) is used to cool it. Therefore, to ensure adhesive reliability during long-term use, it is important that the adhesive strength of the laminated coil is maintained while immersed in high-temperature ATF. This is how the ATF resistance was evaluated. The laminated coil was immersed in ATF at a temperature of 150°C for 500 hours, and then the shear adhesive strength was tested. The shear adhesive strength for measuring the ATF resistance was measured using the shear strength method. Test specimens for the shear strength method were prepared according to ISO 4587. Two 25 x 100 mm test specimens were placed on a 12.5 x 25 mm test specimen. 2The specimens prepared by the shear method were fixed to upper and lower jigs with a constant force and then pulled at a constant speed using a device that measures the tensile strength of the laminated sample. In the case of the shear method, the measured value was the point at which the interface with the minimum adhesive strength fell off from the interface of the laminated sample.

[0044] Interlaminar insulation evaluation: Insulation was measured using a Franklin Insulation Tester, a single-plate test device that measures the surface insulation resistance of electrical steel sheets under a constant pressure and voltage. The current range was 0 to 1,000 amps. The insulation measurement method involved placing one test specimen on a plate so that all electrode contacts were in contact, then applying a pressure of 300 psi (20.4 atm) using a pressure device. When the test pressure was reached, the slide resistor was adjusted and the ammeter reading was taken at a voltage of 0.5 V. This was used to evaluate the interlaminar insulation value. Five specimens were evaluated for each test solution.

[0045] [Table 1]

[0046] As shown in Examples 1 to 3 in Table 1, when polyurethane resin and inorganic pigment barium sulfate (Ba2SO4) were mixed at an appropriate content ratio and 2,4'-MDI (2,4-methylenediphenyl diisocyanate) was used as the aromatic diisocyanate monomer, excellent properties were exhibited in all of the coating adhesion, ATF resistance, peel adhesion, and interlayer insulation.

[0047] Comparative Example 1 is a case where only polyurethane resin is used without mixing barium sulfate (Ba2SO4). The coating adhesion and peel adhesion strength are excellent, but the interlayer insulation properties are 50 Ω·cm 2 / lam., which indicates that the insulation quality is inferior to that required for generators and industrial motors, and that the ATF resistance characteristics are also inferior to those of the examples. Comparative Example 2 is a case where an excessively small amount of barium sulfate (Ba2SO4) was used, and the coating adhesion and peel adhesion strength were excellent, but the interlayer insulation properties were 50 Ω·cm 2 / lam., and it can be confirmed that the ATF resistance is also inferior to that of the Examples.

[0048] Comparative Example 3 was a case in which an excessively large amount of barium sulfate (Ba2SO4) was used, and although the coating adhesion and interlayer insulation properties were excellent, the peel strength was less than 2 N / mm, which was inferior to the peel strength required for generators and industrial motors, and the ATF resistance properties were also inferior to those of the Examples. In Comparative Examples 4 to 12, adhesive coating layers were prepared by changing the aromatic diisocyanate monomer in Examples 1 to 3 to a compound other than 2,4'-MDI (2,4-methylenediphenyl diisocyanate).

[0049] It can be seen that Comparative Examples 4 to 12 all exhibited poor properties, with peel adhesion strengths of less than 2 N / mm, and in particular, Comparative Examples 6, 9, and 12, which used 4,4'-MDI (4,4-methylenediphenyl diisocyanate) as the aromatic diisocyanate, exhibited poor ATF resistance compared to the Examples. Furthermore, Comparative Examples 10 to 12, which contained excessive amounts of barium sulfate (Ba2SO4), exhibited poor coating adhesion properties, with peeling occurring in coating adhesion measurements.

[0050] The present invention is not limited to the examples, and can be manufactured in various different forms, and those skilled in the art will understand that the present invention can be embodied in other specific forms without changing the technical idea or essential characteristics of the present invention. Therefore, the above-described examples should be understood to be illustrative in all respects and not limiting.

Claims

1. It contains polyurethane resin and inorganic pigment, The inorganic pigment is contained in an amount of 20 to 150 parts by weight based on 100 parts by weight of the polyurethane resin, The polyurethane resin is formed by reacting an aromatic diisocyanate monomer represented by the following chemical formula 2 with a polyol. 【Chemistry 2】 In the above formula 2, L is a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C2 to C10 alkynylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C5 to C20 heteroarylene group; n is an integer from 1 to 10.

2. 2. The adhesive coating composition for electrical steel sheets according to claim 1, wherein the polyurethane resin comprises 30 to 50 wt % of the aromatic diisocyanate monomer and 50 to 70 wt % of the polyol.

3. The inorganic pigment is barium sulfate (Ba ２ SO ４ ), titanium dioxide (TiO ２ ), Clay (Al ２ Si ２ O ５ (OH) ４ ), calcium carbonate (CaCO ３ ), silica (SiO ２ ), talc (3MgO.4SiO ２ ・H ２ 2. The adhesive coating composition for electrical steel sheets according to claim 1, wherein the composition is at least one selected from the group consisting of:

4. 2. The adhesive coating composition for electrical steel sheets according to claim 1, further comprising at least one selected from the group consisting of a coupling agent, a wetting agent, a curing agent, and a curing catalyst.

5. 5. The adhesive coating composition for electrical steel sheets according to claim 4, wherein the coupling agent is present in an amount of 0.2 to 3 parts by weight based on 100 parts by weight of the polyurethane resin.

6. 5. The adhesive coating composition for electrical steel sheets according to claim 4, wherein the curing agent is present in an amount of 0.5 to 2 parts by weight based on 100 parts by weight of the polyurethane resin.

7. 5. The adhesive coating composition for electrical steel sheets according to claim 4, wherein the curing catalyst is present in an amount of 0.1 to 1 part by weight based on 100 parts by weight of the polyurethane resin.

8. 5. The adhesive coating composition for electrical steel sheets according to claim 4, wherein the wetting agent is present in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the polyurethane resin.

9. A plurality of electromagnetic steel sheets; a bonding layer located between the plurality of electrical steel sheets, the fusion layer contains a polyurethane resin and an inorganic pigment, The inorganic pigment is contained in an amount of 20 to 150 parts by weight based on 100 parts by weight of the polyurethane resin, The polyurethane resin is formed by reacting an aromatic diisocyanate monomer represented by the following chemical formula 2 with a polyol. 【Chemistry 2】 In the above formula 2, L is a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C2 to C10 alkynylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C5 to C20 heteroarylene group; n is an integer from 1 to 10.

10. applying an adhesive coating composition to one or both sides of an electrical steel sheet and then curing the composition to form an adhesive coating layer; and stacking the plurality of magnetic steel sheets on which the adhesive coating layer is formed and heat-sealing them to form a fusion layer, The adhesive coating composition comprises a polyurethane resin and an inorganic pigment; The inorganic pigment is contained in an amount of 20 to 150 parts by weight based on 100 parts by weight of the polyurethane resin, The method for producing an electrical steel sheet laminate, wherein the polyurethane resin is formed by reacting an aromatic diisocyanate monomer represented by the following chemical formula 2 with a polyol. 【Chemistry 2】 In the above formula 2, L is a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C2 to C10 alkynylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C5 to C20 heteroarylene group; n is an integer from 1 to 10.

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