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

Abstract

An object of the present invention is to provide an adhesive coating composition for magnetic steel sheets, an electromagnetic steel sheet laminate, and a method for producing the same, which improve the adhesive strength between magnetic steel sheets by controlling the components of the adhesive layer formed between magnetic steel sheets. [Solution] The present invention relates to an adhesive coating composition for magnetic steel sheets, which comprises a mixed resin of polyurethane resin and epoxy resin, the mixed resin containing 55 to 98 parts by weight of the polyurethane resin and 2 to 45 parts by weight of the epoxy resin, based on 100 parts by weight of the mixed resin, and the polyurethane resin is formed by reacting an aromatic diisocyanate monomer and a polyol, and to an magnetic steel sheet laminate and a manufacturing method thereof using the same.

Description

[Technical Field]

[0001] The present invention relates to an adhesive coating composition for magnetic steel sheets, an electromagnetic steel sheet laminate, and a manufacturing method thereof. More specifically, the present invention relates to an adhesive coating composition for magnetic steel sheets, an electromagnetic steel sheet laminate, and a manufacturing method thereof, 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, the present invention relates to an adhesive coating composition for magnetic steel sheets, an electromagnetic steel sheet laminate, and a manufacturing method thereof, 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) to improve their magnetic properties after punching, and those that do not require stress relief annealing when the cost loss from heat treatment is greater than the magnetic property benefits from stress relief annealing.

[0003] Insulating coatings are applied during the finishing process of laminates such as motor and generator cores, electric motors, and small transformers, and typically require electrical properties that suppress the generation of 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 multiple sheets are punched into a desired shape and then laminated to form an iron core. Anti-adhesion 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. In addition to these basic properties, the coating solution must also have excellent application workability and long-term usability after mixing. Such insulating coatings can only be manufactured into electrical steel sheet laminates using separate fastening methods such as welding, clamping, and interlocking. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an electrical steel sheet laminate having a bonding layer formed thereon that can bond (fasten) electrical steel sheets 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 manufacturing method thereof that improve the adhesive strength between electrical steel sheets by controlling the components of the bonding layer formed between the electrical steel sheets. [Means for solving the problem]

[0005] The adhesive coating composition for electrical steel sheets of the present invention comprises a mixed resin of polyurethane resin and epoxy resin, the mixed resin comprising 55 to 98 parts by weight of polyurethane resin and 2 to 45 parts by weight of epoxy resin, based on 100 parts by weight of the mixed resin, and the polyurethane resin is formed by reacting an aromatic diisocyanate monomer represented by the following chemical formula 1 with a polyol:

[0006] [ka]

[0007] In the above chemical formula 1, R 1 ~R 10 are each independently hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 20 carbon atoms, or an isocyanate group; R 1 ~R 5 one of which is an isocyanate group, and R6 ~R 10 one of which is an isocyanate group, and R 3 and R 8 and L are simultaneously an isocyanate group, L is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 20 carbon atoms, and n is any one integer of 1 to 10.

[0008] In chemical formula 1, R 1 ~R 5 one of which is an isocyanate, and R 6 ~R 10 one of which is an isocyanate, and R 3 and R 8 is an isocyanate, R 1 and R 10 is also an isocyanate.

[0009] In chemical formula 1, R 1 ~R 5 one of which is an isocyanate, and R 6 ~R 10 one of which is an isocyanate, and R 1 ~R 5 Any one of the following and R 6 ~R 10 It is further excluded that any one of the groups is symmetrical about L and simultaneously an isocyanate.

[0010] The aromatic diisocyanate monomer represented by Chemical Formula 1 is represented by Chemical Formula 2 below.

[0011] [ka]

[0012] In the above chemical formula 2, L is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 20 carbon atoms.

[0013] The polyol is a compound represented by the following chemical formula 3.

[0014] [ka]

[0015] In the above chemical formula 3, R' is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroaryl group having 5 to 20 carbon atoms.

[0016] The polyurethane resin contains 30 to 50% by weight of an aromatic diisocyanate monomer and 50 to 70% by weight of a polyol.

[0017] The epoxy resin has a molecular weight of 5,000 to 20,000 and a hydroxyl group value of 2 to 20 mgKOH / g.

[0018] The electrical steel sheet adhesive coating composition of the present invention further comprises one or more members selected from the group consisting of coupling agents, wetting agents, curing agents, and curing catalysts.

[0019] The coupling agent is contained in an amount of 0.2 to 3 parts by weight based on 100 parts by weight of the mixed resin.

[0020] The curing agent is contained in an amount of 0.5 to 2 parts by weight based on 100 parts by weight of the mixed resin.

[0021] The curing catalyst is contained in an amount of 0.1 to 1 part by weight based on 100 parts by weight of the mixed resin.

[0022] The wetting agent is contained in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the mixed resin.

[0023] The electromagnetic steel sheet laminate of the present invention comprises a plurality of electromagnetic steel sheets and a bonding layer located between the plurality of electromagnetic steel sheets, the bonding layer comprising a mixed resin of a polyurethane resin and an epoxy resin, the mixed resin comprising 55 to 98 parts by weight of polyurethane resin and 2 to 45 parts by weight of epoxy resin based on 100 parts by weight of the mixed resin, the polyurethane resin being formed by reacting an aromatic diisocyanate monomer represented by the following chemical formula 1 with a polyol:

[0024] [ka]

[0025] In the above chemical formula 1, R 1 ~R 10 are each independently hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 20 carbon atoms, or an isocyanate group; R 1 ~R 5 one of which is an isocyanate group, and R 6 ~R 10 one of which is an isocyanate group, and R 3 and R 8 and L are simultaneously an isocyanate group, L is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 20 carbon atoms, and n is any one integer of 1 to 10.

[0026] The method for producing 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 comprises a mixed resin of a polyurethane resin and an epoxy resin, the mixed resin comprising 55 to 98 parts by weight of polyurethane resin and 2 to 45 parts by weight of epoxy resin, based on 100 parts by weight of the mixed resin, and the polyurethane resin is formed by reacting an aromatic diisocyanate monomer represented by the following chemical formula 1 with a polyol:

[0027] [ka]

[0028] In the above chemical formula 1, R 1 ~R 10 are each independently hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 20 carbon atoms, or an isocyanate group; R 1 ~R 5 one of which is an isocyanate group, and R 6 ~R 10 one of which is an isocyanate group, and R 3 and R 8 and L are simultaneously an isocyanate group, L is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 20 carbon atoms, and n is any one integer of 1 to 10. [Effects of the Invention]

[0029] According to the present invention, the components of the adhesive layer formed between the magnetic steel sheets can be controlled to improve the adhesive strength between the magnetic steel sheets. According to the present invention, the electromagnetic steel sheets can be bonded without using existing fastening methods such as welding, clamping, and interlocking, and the noise and vibration suppression effect of the electromagnetic steel sheet laminate is more excellent. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 2 is a schematic diagram of an electromagnetic steel sheet laminate. [Figure 2] FIG. 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

[0031] Terms such as "first," "second," and "third" are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Therefore, 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 for the purpose of referring to particular embodiments only 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 this specification, the term "comprising" refers to the inclusion of specific 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 a part is referred to as being "on" or "on" another part, it means that it is directly on or above the other part, or there may be other parts between them. In contrast, when a part is referred to as being "directly on" another part, there are no other parts between them. 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 to have a meaning consistent with the relevant technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal sense unless otherwise defined.

[0032] Unless otherwise defined, the term "substituted" used herein means that at least one hydrogen atom in a compound is substituted with an alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a silane group, an alkylsilane group, an alkoxysilane group, or an ethyleneoxyl group.

[0033] As used herein, unless otherwise defined, "hetero" means an atom selected from the group consisting of N, O, S, and P.

[0034] The alkyl group may be an alkyl group having 1 to 20 carbon atoms, specifically a lower alkyl group having 1 to 6 carbon atoms, a medium alkyl group having 7 to 10 carbon atoms, or a higher alkyl group having 11 to 20 carbon atoms.

[0035] For example, a C1-C4 alkyl group means that there are from 1 to 4 carbon atoms in the alkyl chain, and is selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and t-butyl. Typical alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like.

[0036] 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, as those skilled in the art may realize, the present invention is not limited to the embodiments set forth herein.

[0037] An adhesive coating composition for electrical steel sheets according to one embodiment of the present invention comprises a mixed resin of a polyurethane resin and an epoxy resin, the mixed resin comprising 55 to 98 parts by weight of polyurethane resin and 2 to 45 parts by weight of epoxy resin, based on 100 parts by weight of the mixed resin, and the polyurethane resin may be formed by reacting an aromatic diisocyanate monomer represented by the following Chemical Formula 1 with a polyol.

[0038] [ka]

[0039] In chemical formula 1, R 1 ~R 10 are each independently hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 20 carbon atoms, or an isocyanate group; R 1 ~R 5 one of which is an isocyanate group, and R 6 ~R 10 one of which is an isocyanate group, and R 3 and R 8 and L are simultaneously an isocyanate group, L is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 20 carbon atoms, and n is any one integer of 1 to 10.

[0040] In one embodiment of the present invention, the mixed resin may contain 55 to 98 parts by weight of polyurethane resin and 2 to 45 parts by weight of epoxy resin, based on 100 parts by weight of the mixed resin. If the polyurethane resin is contained in an excessively large amount, the high-temperature adhesive strength may be poor due to a low degree of crosslinking of the mixed resin layer. If the polyurethane resin is contained in an excessively small amount, the vibration damping effect may be poor due to the low viscoelastic properties of the mixed resin layer. If the epoxy resin is contained in an excessively large amount, the vibration damping effect may be poor due to the low viscoelastic properties of the mixed resin layer, resulting from a high degree of crosslinking. If the epoxy resin is contained in an excessively small amount, the high-temperature adhesive strength may be poor due to a low degree of crosslinking of the mixed resin layer.

[0041] In chemical formula 1, R 1 ~R 5 one of which is an isocyanate, and R 6 ~R 10 one of which is an isocyanate, and R 3 and R 8 is an isocyanate, R 1 and R 10 may further be excluded when simultaneously is an isocyanate.

[0042] In chemical formula 1, R 1 ~R 5 one of which is an isocyanate, and R 6 ~R 10 one of which is an isocyanate, and R 1 ~R 5 Any one of the following and R 6 ~R 10 It may be further excluded that any one of the groups is symmetrical about L and simultaneously an isocyanate.

[0043] In Chemical Formula 1, when isocyanate is bonded at positions symmetrical with respect to L, the coating adhesion, peel adhesion, or ATF resistance of the manufactured electrical steel sheet laminate is inferior, and there is a problem that it cannot be used for self-bonding.

[0044] The aromatic diisocyanate monomer represented by Chemical Formula 1 may be one represented by Chemical Formula 2 below.

[0045] [ka]

[0046] In Chemical Formula 2, L is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 20 carbon atoms.

[0047] The polyol may be a compound represented by the following chemical formula 3:

[0048] [ka]

[0049] In Chemical Formula 3, R' is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroaryl group having 5 to 20 carbon atoms. Specifically, the polyol may be polypropylene glycol.

[0050] The polyol may have a number average molecular weight of 400 to 1000 g / mol.

[0051] The polyurethane resin may contain 30-50 wt% aromatic diisocyanate monomer and 50-70 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 it 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 it is too high, the tacky properties may cause stickiness during long-term storage in a coiled state.

[0052] The epoxy resin may have a molecular weight of 5,000 to 20,000 and a hydroxyl group value of 2 to 20 mgKOH / g.

[0053] The electrical steel sheet adhesive coating composition according to one embodiment of the present invention may further include at least one selected from the group consisting of a coupling agent, a wetting agent, a curing agent, and a curing catalyst.

[0054] The magnetic steel sheet adhesive coating composition according to one embodiment of the present invention 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, and more specifically, may include at least one of a vinyl silane coupling agent and a methacryloxy silane coupling agent. Examples of the vinyl silane coupling agent include vinyl trimethoxy silane and vinyl triethoxy silane. Methacryloxy-based silane coupling agents can include 3-methacryloxypropyl methyldimethoxysilane, 3-methacryloxpropyl trimethoxysilane, 3-methacryloxypropyl methyldiethoxysilane, and 3-methacryloxypropyl triethoxysilane.

[0055] The magnetic steel sheet adhesive coating composition according to one embodiment 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 magnetic steel sheet bonding composition to strengthen the interfacial adhesion between the magnetic steel sheet and the adhesive layer.

[0056] The electrical steel sheet adhesive coating composition according to one embodiment 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.

[0057] The electrical steel sheet adhesive coating composition according to one embodiment of the present invention may further include a curing catalyst to prevent stickiness due to a rapid curing reaction during coil coating. The curing catalyst may include an imidazole-based curing catalyst.

[0058] The magnetic steel sheet adhesive coating composition according to one embodiment of the present invention may contain 0.2 to 3 parts by weight of the coupling agent based on 100 parts by weight of the mixed resin. Specifically, it may contain 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 magnetic steel sheet and the adhesive layer may not be sufficient. If the amount of coupling agent is too large, a precipitate may be formed in the adhesive coating composition due to a reaction between the coupling agents.

[0059] In an embodiment of the present invention, the adhesive coating composition for electrical steel sheets may contain 0.5 to 2 parts by weight of the curing agent based on 100 parts by weight of the mixed resin. Specifically, 0.8 to 1.2 parts by weight of the curing agent may be included. The curing agent functions to adjust 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 reduced, resulting in a sticky adhesive layer surface. Conversely, if the curing agent content is too high, the fastening strength may be reduced after low-temperature welding.

[0060] The magnetic steel sheet adhesive coating composition according to one embodiment of the present invention may contain 0.1 to 1 part by weight of the curing catalyst based on 100 parts by weight of the mixed resin. Specifically, it may contain 0.3 to 0.8 parts by weight. If the curing catalyst content is too high, an over-curing reaction may occur, resulting in poor fastening strength after fusion. If the curing catalyst content is too low, the adhesive layer may not harden, resulting in a sticky surface.

[0061] The adhesive coating composition for electrical steel sheets according to one embodiment of the present invention may contain 0.05 to 0.5 parts by weight of the wetting agent, based on 100 parts by weight of the mixed resin. Specifically, the wetting agent may contain 0.05 to 0.15 parts by weight. If the amount of wetting agent is too high, excessive bubbles may be generated in the coating solution, resulting in defects in the coating layer. If the amount of wetting agent is too low, the wettability of the coating layer may be reduced, resulting in defects on the coating surface.

[0062] In addition to the above components, the adhesive coating composition may contain a solvent to facilitate application and uniformly disperse the components. Examples of the solvent include water, alcohol, etc. The solvent may be included in an amount of 1 to 20 parts by weight per 100 parts by weight of the mixed resin.

[0063] In one embodiment of the present invention, an electrical steel sheet lamination is provided. An electrical steel sheet laminate according to one embodiment 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 an electrical steel sheet laminate according to one embodiment of the present invention. As shown in Fig. 1, the electrical steel sheet laminate has a configuration in which a plurality of electrical steel sheets are stacked.

[0064] Fig. 2 shows a schematic cross-sectional view of an electrical steel sheet laminate according to an embodiment of the present invention. As shown in Fig. 2, an electrical steel sheet laminate 100 according to an embodiment 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.

[0065] The electrical steel sheet laminate according to one embodiment of the present invention may be a laminate in which different electrical steel sheets are heat-fused together by simply forming a bonding layer using the above-described adhesive coating composition, without using existing methods such as welding, clamping, or interlocking.

[0066] In this case, the laminate of magnetic steel sheets has excellent high-temperature adhesiveness and high-temperature oil resistance even after heat fusion.

[0067] Each component will be described in detail below. General non-oriented or oriented electrical steel sheets can be used without any restrictions as the electrical steel sheets 10. In one embodiment of the present invention, the main configuration is to form a fusion layer 20 between a plurality of electrical steel sheets 10 to manufacture an electrical steel sheet laminate 100, so a detailed description of the electrical steel sheets 10 will be omitted.

[0068] The adhesive layer 20 is formed between the plurality of magnetic steel sheets 10 and has such a strong adhesive force that the plurality of magnetic steel sheets 10 can be bonded together without using existing fastening methods such as welding, clamping, or interlocking.

[0069] The adhesive layer 20 is formed by coating the surface with an adhesive coating composition, curing it to form an adhesive coating layer, and then stacking and heat-sealing the layers 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.

[0070] In one embodiment of the present invention, the adhesive layer 20 comprises a mixed resin of polyurethane resin and epoxy resin. The polyurethane resin, epoxy resin, and mixed resin thereof have been described in detail above in connection with the adhesive coating composition, so a duplicated description will be omitted. The mixed resin of polyurethane resin and epoxy resin remains intact during the adhesive 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 in connection with the adhesive coating composition, so a duplicated description will be omitted.

[0071] Therefore, the adhesive layer may include 100 parts by weight of mixed 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. The thickness of the adhesive layer 20 may be 1 μm to 8 μm. If the adhesive layer is too thin, the adhesive strength may decrease rapidly, and 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 may be 4 μm to 6 μm.

[0072] 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, and 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-sealing the stacked electrical steel sheets to form a fusion layer.

[0073] Each step will be explained in detail below. First, an adhesive coating composition is prepared. The adhesive coating composition has been described above, so a duplicated description will be omitted. Next, the adhesive coating composition is coated on the surface of the electrical steel sheet and then cured to form an adhesive coating layer, which can be performed at a temperature of 150 to 250°C to cure the adhesive coating composition.

[0074] A plurality of magnetic steel sheets having 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. The heat-sealing step can be performed under conditions of a temperature of 150 to 250°C, a pressure of 0.05 to 5.0 MPa, and a pressurizing time of 0.1 to 120 minutes. Each of 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 in this way, the electrical steel sheets can be heat-sealed densely 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 may be 10° C. / min to 1000° C. / min.

[0075] Although the present invention may be embodied in many different forms and is not limited to the embodiments set forth herein, the present invention will be described in detail below so that those skilled in the art can easily practice the present invention. [Example]

[0076] Experimental Example 1 Non-oriented electrical steel sheets (50 x 50 mm, 0.35 mm thick) were prepared as test pieces. The adhesive coating solution was applied to the top and bottom of each test piece using a bar coater and a roll coater to a uniform thickness. The test piece was cured at a sheet temperature of 200°C for 20 seconds, and then gradually cooled in air to form an adhesive coating layer.

[0077] The adhesive coating solution used contained 100 parts by weight of a mixed resin of polyurethane resin and epoxy resin, 0.5 parts by weight of a silane coupling agent, 0.1 parts by weight of a silicone-based wetting agent, 1 part by weight of a dicyandiamide-based curing agent, and 0.5 parts by weight of an 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 epoxy resin used had a molecular weight of 1,000-20,000 and a hydroxyl value of 2-20 mgKOH / g. The content ratios of the polyurethane resin and epoxy resin used, as well as the types and content ratios of the isocyanate monomer and polyol used in the polyurethane resin preparation, are shown in Table 1 below. 。

[0078] In Table 1, MDI means methylene diphenyl diisocyanate, TDI means toluene diisocyanate, and PPG means polypropylene glycol (molecular weight 425 g / mol).

[0079] 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 0.5 MPa to produce a magnetic steel sheet laminate. After heat-sealing, the thickness of the fused layer was approximately 6 μm. The heat-sealed laminates were evaluated based on the mixing ratio of the resins in the coating composition and the type of aromatic diisocyanate monomer used. Specifically, the coating adhesion, peel strength (T-peel, N / mm), ATF resistance, damping ratio, and high-temperature adhesion were evaluated and the results are shown in Table 1 below.

[0080] The methods for measuring each property are as follows.

[0081] Coating adhesion measurement method: The coating adhesion test specimen was prepared based on ISO 1519. The coated specimen was prepared as a sample of 30 x 300 mm and bent 180 degrees onto a 10 mm diameter iron cylinder. Tape was then attached to the bent part 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.

[0082] Peel adhesion strength (T-peel, N / mm): The specimen specifications for the T-Peel off measurement were prepared according to ISO 11339. Two 25 x 200 mm specimens were placed on a 25 x 150 mm 2 After bonding the area, the unbonded area was bent 90° to prepare a T-shaped tensile test piece.

[0083] The specimens prepared using the T-Peel off method were fixed to the upper and lower jigs with a constant force and pulled at a constant speed, and the tensile strength of the laminated sample was measured using a device that measures this. In the case of the shear method, the measured value was the point at which the interface with the smallest adhesive strength among the interfaces of the laminated sample fell off. The temperature of the specimen was maintained at 60°C using a heating device, and the adhesive strength was measured.

[0084] ATF resistance evaluation method: 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. Therefore, ATF resistance was evaluated. The manufactured 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 ATF resistance was measured using the shear strength method. The specimen standard for shear method measurement was prepared in accordance with ISO 4587. Two 25 x 100 mm specimens were combined into a 12.5 x 25 mm specimen. 2A shear test specimen was prepared by heat fusing under the conditions of bonding an area of ​​100 mm. The test specimen prepared by the shear test was fixed to the 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 test, the measured value was the point where the interface with the minimum adhesive strength among the interfaces of the laminated sample fell off.

[0085] Noise suppression characteristic evaluation: A ring-type motor core was manufactured to evaluate the noise characteristics generated by the motor core in the drive motor. A ring core with an outer diameter of 128 mm, an inner diameter of 90 mm, and a height of 45 mm was manufactured by punching and heat-sealing a 0.27 mm non-oriented electrical steel sheet coated with a coating agent. The axial dynamic characteristics of the ring core manufactured in this way were measured. To understand the dynamic characteristics (natural frequency, natural mode, damping ratio) of a machine or structure, a transfer function is typically used, which applies an external force and determines the dynamic response to it. This function indicates the ratio of the response to an external force (F). When analyzing frequency as a response, it is called the frequency response function (FRF), and is the most commonly used basic function for interpreting dynamic characteristics. The damping ratio was measured through this FRF characteristic analysis. The higher the damping ratio, the better the vibration absorption and the less vibration and noise are generated.

[0086] High temperature adhesive strength evaluation: Shear adhesive strength for measuring high temperature adhesive strength was measured using the shear strength method. The specimen specifications for shear method measurement were prepared according to ISO 4587. Two 25 x 100 mm specimens were cut into 12.5 x 25 mm pieces using the coating agent. 2The shear method specimens were prepared by heat fusing under the conditions described above. The specimens prepared by the shear method were placed in a tensile machine with a heating furnace at a high ambient temperature, and then fixed to upper and lower jigs with a constant force. The tensile strength of the laminated sample was measured using a device that pulled the laminated sample at a constant speed. 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 160°C using a heating device, and the adhesive strength was measured.

[0087] [Table 1]

[0088] As shown in Table 1, when polyurethane resin and epoxy resin were mixed at an appropriate content ratio as in Examples 1 to 3 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, peel adhesion, ATF resistance, vibration absorption, and high-temperature adhesion.

[0089] Comparative Example 1 is a case where only polyurethane resin is used without mixing epoxy resin, and although the coating adhesion, peel adhesion strength, and vibration absorption properties are excellent, the high temperature adhesion strength is inferior, showing a value of less than 1 MPa, and the ATF resistance properties are also inferior.

[0090] Comparative Example 2 is a case where only epoxy resin is used without mixing polyurethane resin. It has excellent coating adhesion, ATF resistance, and high-temperature adhesion, but poor peel adhesion and a damping ratio of less than 0.03, indicating poor noise and vibration suppression effects.

[0091] Comparative Example 3 has a low polyurethane resin content and a high epoxy resin content, and it can be seen that the coating adhesion, ATF resistance, and high-temperature adhesion are excellent, but the peel adhesion and vibration absorption are poor.

[0092] 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).

[0093] In the case of Comparative Examples 4, 7, and 10, in which 2,4'-TDI (2,4-toluene diisocyanate) was used as the aromatic diisocyanate, the coating adhesion, ATF resistance, and high-temperature adhesion were good, but the peel adhesion and vibration absorption were inferior to those of the Examples.

[0094] In the cases of Comparative Examples 5, 8, and 11, in which 2,2'-MDI (2,2-methylene diphenyl diisocyanate) was used as the aromatic diisocyanate, the coating adhesion, ATF resistance, and high-temperature adhesion were good, but the peel adhesion and vibration absorption were inferior to those of the Examples.

[0095] In the case of Comparative Examples 6, 9, and 12, in which 4,4'-MDI (4,4-methylenediphenyl diisocyanate) was used as the aromatic diisocyanate, the coating adhesion, vibration absorption, and high-temperature adhesion were good, but the peel adhesion and ATF resistance were inferior to those of the Examples.

[0096] The present invention is not limited to the examples, and can be manufactured in various different forms, and a person skilled in the art to which the present invention pertains can understand that the present invention can be embodied in other specific forms without changing the technical idea or essential features of the present invention. Therefore, it should be understood that the above-described examples are illustrative in all respects and not limiting.

Claims

1. It contains a mixed resin of polyurethane resin and epoxy resin, The mixed resin includes 55 to 98 parts by weight of the polyurethane resin and 2 to 45 parts by weight of the epoxy resin, based on 100 parts by weight of the mixed resin; The polyurethane resin is formed by reacting an aromatic diisocyanate monomer represented by the following formula 2 with a polyol. 【Chemistry 2】 In the above chemical formula 2, L is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 20 carbon atoms; 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 contains 30 to 50 wt % of the aromatic diisocyanate monomer and 50 to 70 wt % of the polyol.

3. 2. The adhesive coating composition for electrical steel sheets according to claim 1, wherein the epoxy resin has a molecular weight of 5,000 to 20,000 and a hydroxyl value of 2 to 20 mgKOH / g.

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 mixed 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 mixed 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 mixed 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 mixed resin.

9. A plurality of electrical steel sheets; and a bonding layer located between the plurality of electrical steel sheets, The fusion layer contains a mixed resin of a polyurethane resin and an epoxy resin, The mixed resin includes 55 to 98 parts by weight of the polyurethane resin and 2 to 45 parts by weight of the epoxy resin, based on 100 parts by weight of the mixed 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 chemical formula 2, L is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 20 carbon atoms; 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 a plurality of the magnetic steel sheets on which the adhesive coating layer is formed, and heat-sealing the stacked magnetic steel sheets to form an adhesive layer; The adhesive coating composition comprises a mixed resin of a polyurethane resin and an epoxy resin, The mixed resin includes 55 to 98 parts by weight of the polyurethane resin and 2 to 45 parts by weight of the epoxy resin, based on 100 parts by weight of the mixed 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 chemical formula 2, L is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 20 carbon atoms; n is an integer from 1 to 10.

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