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

Abstract

The present invention provides an adhesive coating composition for magnetic steel sheets, an electromagnetic steel sheet laminate, and a method for manufacturing the same, which are used to form a bonding layer that can bond (fasten) magnetic steel sheets without using existing fastening methods such as welding, clamping, interlocking, etc. More specifically, the present invention provides an adhesive coating composition for magnetic steel sheets, an electromagnetic steel sheet laminate, and a method for manufacturing the same, which improve the adhesive strength between magnetic steel sheets by controlling the components of the bonding layer formed between the magnetic steel sheets. [Solution] The adhesive coating composition for electrical steel sheets of the present invention comprises a mixed resin of a urethane resin and an epoxy resin, wherein the urethane resin comprises repeating units represented by Chemical Formula 1 and Chemical Formula 2, and the mixed resin contains 20 to 80 parts by weight of the urethane resin and 20 to 80 parts by weight of the epoxy resin, based on 100 parts by weight of the mixed resin, and the urethane resin comprises repeating units represented by Chemical Formula 3 and Chemical Formula 2 below.

Description

[Technical Field]

[0001] The present invention relates to an adhesive coating composition for magnetic steel sheets, an magnetic steel sheet laminate, and a manufacturing method thereof. More particularly, the present invention relates to an adhesive coating composition for magnetic steel sheets, an magnetic steel sheet laminate, and a manufacturing method thereof, which form a bonding layer that can bond (fasten) magnetic steel sheets without using existing fastening methods such as welding, clamping, or interlocking, and further, which control the components of the bonding layer formed between the magnetic steel sheets, thereby improving the adhesive strength and noise suppression properties of the magnetic steel sheet laminate. [Background technology]

[0002] Non-oriented electrical steel sheet is a steel sheet with uniform magnetic properties in all directions on the rolled sheet, and is 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 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 for motor and generator cores, electric motors, small transformers, etc., 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 a large number of sheets are punched into a predetermined 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 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]

[0004] The present invention provides an adhesive coating composition for electrical steel sheets, an electrical steel sheet laminate, and a method for manufacturing the same. Specifically, the present invention provides an adhesive coating composition for electrical steel sheets, an electrical steel sheet laminate, and a method for manufacturing the same, which form a bonding layer that can bond (fasten) electrical steel sheets without using existing fastening methods such as welding, clamping, or interlocking. More specifically, the present invention provides an adhesive coating composition for electrical steel sheets, an electrical steel sheet laminate, and a method for manufacturing the same, which 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 a urethane resin and an epoxy resin, and the urethane resin comprises repeating units represented by the following Chemical Formula 1 and the following Chemical Formula 2.

[0006] [ka]

[0007] [ka] (In the above Chemical Formula 1 and Chemical Formula 2, R 1 L each independently represents 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, a hydroxy group, or a halogen atom. 1 , L 2 , L 3 represents a single bond or a divalent linking group. n represents an integer of 1 to 50.

[0008] Based on 100 parts by weight of the mixed resin, the urethane resin may be contained in an amount of 20 to 80 parts by weight, and the epoxy resin may be contained in an amount of 20 to 80 parts by weight. The urethane resin may include repeating units represented by the following Chemical Formula 3 and Chemical Formula 2.

[0009] [ka] (In the above-mentioned Chemical Formula 3, R 1 L each independently represents 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, a hydroxy group, or a halogen atom. 1 represents a single bond or a divalent linking group.

[0010] The urethane resin may be formed by reacting a diisocyanate monomer with a polyol represented by the following chemical formula 4.

[0011] [ka] (In the above-mentioned Chemical Formula 4, L 2 , L 3 represents a single bond or a divalent linking group. n represents an integer of 1 to 50.

[0012] The diisocyanate monomer may include an aromatic diisocyanate monomer. The aromatic diisocyanate monomer may be a compound represented by the following chemical formula 5:

[0013] [ka] (In the above-mentioned Chemical Formula 5, R 1 ~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, a hydroxy group, a halogen element, or an isocyanate group; At least one of R1 to R5 is an isocyanate group, At least one of R6 to R10 is an isocyanate group, The case where R3 and R8 are simultaneously isocyanate groups is excluded. 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.

[0014] The epoxy resin may have a number average molecular weight of 5,000 to 20,000 and a hydroxyl group value of 2 to 20 mgKOH / g.

[0015] 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 coupling agent can be contained in an amount of 0.2 to 3 parts by weight based on 100 parts by weight of the mixed resin. The curing agent can be contained in an amount of 0.5 to 2 parts by weight based on 100 parts by weight of the mixed resin. The curing catalyst may be contained in an amount of 0.1 to 1 part by weight based on 100 parts by weight of the mixed resin. The wetting agent may be contained in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the mixed resin.

[0016] 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, the bonding layer including a mixed resin of a urethane resin and an epoxy resin, and the urethane resin including repeating units represented by the following chemical formula 1 and the following chemical formula 2.

[0017] [ka]

[0018] [ka] (In the above Chemical Formula 1 and Chemical Formula 2, R 1L each independently represents 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, a hydroxy group, or a halogen atom. 1 , L 2 , L 3 represents a single bond or a divalent linking group. n represents an integer of 1 to 50.

[0019] The fusion layer may contain 20 to 80 parts by weight of urethane resin and 20 to 80 parts by weight of epoxy resin based on 100 parts by weight of the mixed resin. 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 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 them to form a fusion layer. [Effects of the Invention]

[0020] 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. Furthermore, 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 even more excellent. Furthermore, by using a urethane resin with a specific chemical structure, the adhesive strength is excellent even in an automobile transmission oil environment. [Brief explanation of the drawings]

[0021] [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 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] 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 may 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 form includes the plural form unless the context clearly dictates otherwise. As used in the specification, the meaning of "comprising" embodies 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.

[0023] When a part is referred to as being "on" another part, it may be directly on top of the other part, or there may be other parts between them. In contrast, when a part is referred to as being "directly on top" of 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.

[0024] In this specification, unless otherwise defined, the term "substituted" means that at least one hydrogen in the 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, and specifically may be a C1 to C6 lower alkyl group, a C7 to C10 medium alkyl group, or a C11 to C20 higher alkyl group. For example, a C1-C4 alkyl group means that there are 1 to 4 carbon atoms in the alkyl chain, which indicates that the alkyl group 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.

[0025] 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 the present invention may be embodied in many different forms, it is not limited to the embodiments set forth herein. The electrical steel sheet adhesive coating composition of the present invention comprises a mixed resin of a urethane resin and an epoxy resin.

[0026] Each component will be explained below. First, the urethane resin serves to lower the degree of crosslinking of the mixed resin and to enhance the viscoelastic properties. In the present invention, the coating adhesion, peel adhesion strength, and ATF resistance of the manufactured electrical steel sheet laminate can be improved by including a urethane resin having a specific chemical structure. Specifically, the urethane resin includes repeating units represented by the following chemical formula 1 and the following chemical formula 2.

[0027] [ka]

[0028] [ka] (In the above Chemical Formula 1 and Chemical Formula 2, R 1L each independently represents 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, a hydroxy group, or a halogen atom. 1 , L 2 , L 3 represents a single bond or a divalent linking group. n represents an integer of 1 to 50.

[0029] Chemical formula 1 is a chemical structure derived from aromatic diisocyanate, which is used as a raw material in the synthesis of urethane resin. The structure of Chemical Formula 1 can improve heat resistance due to the hardness provided by the two benzene ring structures in the aromatic diisocyanate. In chemical formula 1, R 1 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, a hydroxy group, or a halogen element. 1 is connected to the interior of the benzene ring, which means that it is substituted at any of the six substitution positions of the benzene ring. 1 may each independently be hydrogen, deuterium, or a substituted or unsubstituted C1 to C10 alkyl group. 1 may each independently be hydrogen or deuterium.

[0030] In chemical formula 1, L 1 represents a single bond or a divalent linking group. Specifically, the divalent linking group may be one or more of 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, a substituted or unsubstituted C5 to C20 heteroarylene group, -O-, -(CO)-, -S-, -N-, and P-. More specifically, L 1may be 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. 1 may be a substituted or unsubstituted C1 to C10 alkylene group. Specifically, the repeating unit of Chemical Formula 1 may be represented as Chemical Formula 3 below.

[0031] [ka] (In the above-mentioned Chemical Formula 3, R 1 L each independently represents 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, a hydroxy group, or a halogen atom. 1 represents a single bond or a divalent linking group.

[0032] As shown in Chemical Formula 3, the linking group L 1 By not bonding the -NCOO- group and the linking groups to other repeating units to symmetrical positions on the two benzene rings, the coating adhesion, peel adhesion strength, or ATF resistance of the produced electrical steel sheet laminate can be further improved. In chemical formula 3, R 1 and L 1 is the same as that explained in the above-mentioned Chemical Formula 1, so a duplicate explanation will be omitted.

[0033] The repeating unit of Chemical Formula 1 may be contained in the urethane resin in an amount of 20 to 50% by weight. If the repeating unit of Chemical Formula 1 is too small, the high-temperature fastening strength of the urethane resin may decrease, while if it is too large, the thermal fusion property may decrease. More specifically, the repeating unit of Chemical Formula 1 may be contained in the urethane resin in an amount of 30 to 40% by weight. The ratio of the repeating unit of Chemical Formula 1 can be adjusted by the ratio of the aromatic diisocyanate monomer added during the production of the urethane resin.

[0034] Chemical formula 2 is a chemical structure derived from polyol, which is used as a raw material in the synthesis of urethane resin. The structure of Chemical Formula 2 improves heat fusion properties due to the increased flexibility of the numerous -COO- and O- structures. In chemical formula 2, L 2 and L 3 are each independently a single bond or a divalent linking group. Specifically, the divalent linking group may be one or more of 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, a substituted or unsubstituted C5 to C20 heteroarylene group, -O-, -(CO)-, -S-, -N-, and P-. More specifically, L 1 may be 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. 1 may be a substituted or unsubstituted C1 to C10 alkylene group. n may be an integer of 1 to 50. If n is too large, problems may arise in terms of heat resistance. More specifically, n may be an integer of 1 to 20.

[0035] The repeating unit of Chemical Formula 2 may be contained in the urethane resin in an amount of 50 to 80% by weight. If the repeating unit of Chemical Formula 2 is too small, the problem of reduced thermal fusion may occur. If the repeating unit of Chemical Formula 2 is too large, the problem of reduced high-temperature fastening strength of the urethane resin may occur. More specifically, the repeating unit of Chemical Formula 2 may be contained in the urethane resin in an amount of 60 to 70% by weight. The ratio of the repeating unit of Chemical Formula 2 can be adjusted by the ratio of polyol added during the production of the urethane resin. The urethane resin may be formed by reacting a diisocyanate monomer with a polyol represented by the following chemical formula 4:

[0036] [ka] (In the above-mentioned Chemical Formula 4, L 2 , L 3 represents a single bond or a divalent linking group. n represents an integer of 1 to 50.

[0037] The polyol of Chemical Formula 4 has been explained in connection with the explanation of the repeating unit of Chemical Formula 2 in the urethane resin, so a duplicate explanation will be omitted. 2 , L 3 and n are the same as those in the description of Chemical Formula 2. The polyol may have a number average molecular weight of 400 to 1000 g / mol. If the molecular weight is too small, problems may arise in terms of heat fusion. If the molecular weight is too large, problems may arise in terms of heat resistance. More specifically, the number average molecular weight of the polyol may be 500 to 800. The aromatic diisocyanate monomer may be a compound represented by the following chemical formula 5:

[0038] [ka] (In the above-mentioned Chemical Formula 5, R 1 ~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, a hydroxy group, a halogen element, or an isocyanate group; At least one of R1 to R5 is an isocyanate group, At least one of R6 to R10 is an isocyanate group, The case where R3 and R8 are simultaneously isocyanate groups is excluded. 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.

[0039] The aromatic diisocyanate of Chemical Formula 5 has been explained in relation to the explanation of the repeating unit of Chemical Formula 1 of the urethane resin, so a duplicate explanation will be omitted. 1 ~R 10 is R in chemical formula 1 1 The L in Chemical Formula 5 is the same as the L in Chemical Formula 1. 1 This is the same as the description above. The aromatic diisocyanate monomer may be represented by the following formula 6:

[0040] [ka] (In 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.) More specifically, L may be a substituted or unsubstituted C1 to C10 alkylene group.

[0041] More specifically, L may be a methylene group. The aromatic diisocyanate monomer may be methylene diphenyl diisocyanate.

[0042] The urethane resin may be included in an amount of 20 to 80 parts by weight based on 100 parts by weight of the mixed resin. If the amount of urethane resin is too small, the vibration suppression effect may be reduced due to the low viscoelasticity of the mixed resin layer. If the amount of urethane resin is too large, the high-temperature adhesive strength may be reduced due to the low degree of crosslinking of the mixed resin layer. More specifically, the urethane resin may be included in an amount of 30 to 70 parts by weight based on 100 parts by weight of the mixed resin. In the present invention, an epoxy resin is used together with the urethane resin, and the epoxy resin serves to increase the degree of crosslinking and improve high-temperature adhesive strength.

[0043] The epoxy resin is not particularly limited, but may include one or more of bisphenol A type epoxy resin, bisphenol E type epoxy resin, alicyclic epoxy, and aliphatic polyglycidyl type epoxy. The epoxy resin may have a number average molecular weight of 1,000 to 20,000 and a hydroxyl group value of 2 to 20 mgKOH / g. Epoxy resins with appropriate molecular weights and hydroxyl group values ​​are advantageous in terms of heat fusion properties and heat resistance. More specifically, the number average molecular weight may be 5,000 to 15,000 and the hydroxyl group value may be 5 to 15 mgKOH / g.

[0044] 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 of the present invention may further contain 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 an epoxy-based silane coupling agent and an amino-based silane coupling agent. More specific examples include 2(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltriethoxysilane, and 3-aminopropyltrimethoxysilane. When a coupling agent is further included, it can be included in an amount of 0.2 to 3 parts by weight based on 100 parts by weight of the mixed resin. 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 sufficiently obtained. If the amount of coupling agent is too large, a precipitate may occur in the adhesive coating composition due to a reaction between the coupling agents. Specifically, it can be included in an amount of 0.2 to 1 part by weight.

[0045] The adhesive coating composition for magnetic steel sheets of the present invention may further include a silicone-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 the silicone-based wetting additive may be polyether-modified polydimethylsiloxane. The wetting agent can be added to the bonding composition for magnetic steel sheets to strengthen the interfacial adhesion between the magnetic steel sheet and the adhesive layer.

[0046] In the electrical steel sheet adhesive coating composition of the present invention, the wetting agent may be contained in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the mixed resin. If the amount of wetting agent is too high, problems such as defects in the coating layer due to excessive bubbles in the coating solution may occur, while if the amount of wetting agent is too low, problems such as defects on the coating surface due to reduced wettability of the coating layer may occur. Specifically, the amount of wetting agent may be 0.05 to 0.15 parts by weight.

[0047] 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.

[0048] The electrical steel sheet adhesive coating composition of the present invention may contain 1 to 10 parts by weight of a curing agent based on 100 parts by weight of the mixed resin. 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. Specifically, the curing agent may contain 1 to 5 parts by weight.

[0049] The electrical steel sheet adhesive coating composition of the present invention may further include a curing catalyst to prevent stickiness due to uncured coating caused by a rapid curing reaction during coil coating. The curing catalyst may include an imidazole-based curing catalyst. The electrical steel sheet adhesive coating composition of the present invention may contain 0.1 to 5 parts by weight of a curing catalyst based on 100 parts by weight of the mixed resin. If the curing catalyst content is too high, an over-curing reaction may occur, resulting in a deterioration in fastening strength after fusion. If the curing catalyst content is too low, an under-curing reaction may occur, resulting in a sticky surface on the fusion layer. Specifically, the curing catalyst may be contained in an amount of 0.5 to 3 parts by weight.

[0050] In addition to the above-mentioned 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 contained in an amount of 200 to 2000 parts by weight per 100 parts by weight of the mixed resin. The present invention provides an electrical steel sheet laminate. 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 electrical steel sheet laminate has a configuration in which a plurality of electrical steel sheets are stacked.

[0051] A schematic cross-sectional view of an electrical steel sheet laminate of the present invention is shown in Figure 2. As shown in Figure 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 may be a laminate in which different electrical steel sheets are heat-fused together by simply forming a bonding layer using the adhesive coating composition described above, without using existing methods such as welding, clamping, or interlocking. In this case, the laminate of magnetic steel sheets has excellent high-temperature adhesiveness and high-temperature oil resistance even after heat fusion.

[0052] Each component will be described in detail below. General non-oriented or grain-oriented electrical steel sheets can be used without any restrictions as the electrical steel sheets 10. Since the main configuration of the present invention is to form a fusion layer 20 between a plurality of electrical steel sheets 10 to produce an electrical steel sheet laminate 100, a detailed description of the electrical steel sheets 10 will be omitted. More specifically, the electrical steel sheets 10 can be non-oriented electrical steel sheets.

[0053] The adhesive layer 20 is formed between the plurality of electromagnetic steel sheets 10, and has such strong adhesive strength that the plurality of electromagnetic steel sheets 10 can be bonded together without using existing fastening methods such as welding, clamping, or interlocking. 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.

[0054] In the present invention, the adhesive layer 20 comprises a mixed resin of a urethane resin and an epoxy resin. The urethane resin, the epoxy resin, and the mixed resin thereof have been described in detail in connection with the adhesive coating composition, and therefore a repeated description will be omitted. The chemical structures and ratios of the urethane resin and the epoxy resin remain unchanged during the process of forming the adhesive layer. 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 in connection with the adhesive coating composition, and therefore a repeated description will be omitted.

[0055] The fusion layer 20 may contain 20 to 80 parts by weight of urethane resin and 20 to 80 parts by weight of epoxy resin based on 100 parts by weight of the mixed resin. The adhesive layer 20 may further include 0.2 to 3 parts by weight of a coupling agent, 0.05 to 0.5 parts by weight of a wetting agent, 0.5 to 2 parts by weight of a curing agent, and 0.1 to 1 part by weight of a 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 1 μm to 3 μm.

[0056] In the present invention, the electrical steel sheet laminate has improved paint adhesion, peel adhesion, and ATF resistance. When a drive motor is used in an automobile, a lot of heat is generated during long-term rotation at high speed, and ATF (Automotive Transmission Fluid) is used to cool the heat. 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. 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 the stacked sheets to form a fusion layer. Each step will be explained in detail below.

[0057] First, an adhesive coating composition is prepared. The adhesive coating composition has been described above, so a duplicate 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 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 a fusion layer 20. Through the heat-sealing step, the polymer components in the adhesive coating layers are heat-sealed to form a fusion layer.

[0058] 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. The above conditions may be satisfied independently, or two or more conditions may 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 tightly 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 may be 10° C. / min to 1000° C. / min.

[0059] 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.

[0060] 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 pieces were cured at a sheet temperature of 200°C for 20 seconds and then slowly cooled in air to form an adhesive coating layer. 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 (3-glycidoxypropyltriethoxysilane), 0.1 parts by weight of a silicone-based wetting agent (polyether-modified siloxane), 1 part by weight of a dicyandiamide-based curing agent (adipic acid dihydrazide), and 0.5 parts by weight of an imidazole-based curing catalyst (1,2 dimethylimidazole).

[0061] The polyurethane resin was prepared by reacting 40% by weight of 2,4-methylenediphenyldiisocyanate monomer with 60% by weight of polyethylene carbonate diol having a molecular weight of 425 g / mol, based on the total weight of the polyurethane resin. The epoxy resin used was a bisphenol A-based epoxy resin with a molecular weight of 10,000 and a hydroxyl value of 10 mgKOH / g. The content ratio of the polyurethane resin and epoxy resin used, and the types and content ratio of the isocyanate monomer and polyol used in producing the polyurethane resin are as shown in Table 1 below.

[0062] In Table 1, MDI means methylene diphenyl diisocyanate, TDI means toluene diisocyanate, and PCD means polyethylene carbonate diol (number 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 0.5 MPa to produce a magnetic steel sheet laminate. The thickness of the heat-sealed layer was approximately 3 μm. The heat-sealed laminates were evaluated based on the mixing ratio of the mixed resins in the coating composition and the type of aromatic diisocyanate monomer used. Specifically, the coating adhesion, peel adhesion (T-peel, N / mm), ATF resistance, and high-temperature adhesion were evaluated, and the results are shown in Table 1 below.

[0063] The methods for measuring each property are as follows. Coating adhesion measurement method: Test specimens for coating adhesion measurement were prepared based on ISO 1519. The coated test specimens were prepared as 30 x 300 mm samples, which were then bent 180 degrees onto a 10 mm diameter iron cylinder. Tape was then applied to the bent area, and the coating layer was visually inspected for peeling. If peeling occurred, the test specimen was rated as NG, and if no peeling occurred, it was judged as OK.

[0064] Peel adhesion strength (T-peel, N / mm): The test specimen for the peel method (T-Peel off) measurement was prepared according to ISO 11339. Two 25 x 200 mm test specimens were placed on a 25 x 150 mm2 After bonding over an area of ​​100 mm, the unbonded area was bent 90° to prepare a T-shaped tensile test specimen. The test 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, using a device to measure 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 smallest adhesive strength among the interfaces of the laminated sample fell off. The temperature of the test specimen was maintained at 60°C using a heating device, and the adhesive strength was measured.

[0065] ATF resistance evaluation method: The manufactured laminated coil was immersed in ATF (SP4M-1) at a temperature of 160°C for 1000 hours, and then the shear adhesive strength was tested. The shear adhesive strength for measuring the ATF resistance was measured by the shear strength method. The test specimen for the shear strength measurement was prepared in accordance with ISO 4587. Two 25 x 100 mm test specimens were placed on a 12.5 x 25 mm 2 The specimens prepared by the shear method were fixed to upper and lower jigs with a constant force and 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 smallest adhesive strength among the interfaces of the laminated sample fell off.

[0066] High-temperature adhesive strength evaluation: Shear adhesive strength for measuring high-temperature adhesive strength was measured using the shear strength method. The test specimen standard for shear method measurement was prepared based on ISO 4587. Two 25 x 100 mm test specimens were cut into 12.5 x 25 mm pieces using the coating agent. 2The shear test specimens were prepared by heat fusing under the conditions described above. The test specimens prepared by the shear test were placed in a tensile machine with a heating furnace at a high ambient temperature, fixed to upper and lower jigs with a constant force, and pulled at a constant speed using a device to measure the tensile strength of the laminated sample. In the case of the shear test, the measured value was the point at which the interface with the smallest adhesive strength between the laminated sample interfaces fell off. The temperature of the test specimen was maintained at 180°C using a heating device, and the adhesive strength was measured.

[0067] [Table 1]

[0068] 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 coating adhesion, peel adhesion, ATF resistance, and high-temperature adhesion. Comparative Example 1 is a case where only urethane resin is used without mixing epoxy resin. In this case, the peel adhesion strength is excellent, but the high temperature adhesion strength and ATF resistance properties show values ​​of less than 1 MPa, indicating deterioration. Comparative Example 2 is a case where only epoxy resin is used without mixing urethane resin. In this case, the high temperature adhesive strength and ATF resistance properties are excellent, but the peel adhesive strength is less than 0.5, confirming that the adhesive strength has deteriorated. In Comparative Examples 3 to 11, adhesive coating layers were produced by changing the aromatic diisocyanate monomer in Examples 1 to 3 to a compound other than 4'-MDI (2,4-methylenediphenyl diisocyanate).

[0069] In the case of Comparative Examples 3, 6 and 9, 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 it was confirmed that the peel adhesion was inferior to that of the Examples. In the cases of Comparative Examples 4, 7 and 10, in which 2,2'-MDI (2,2-methylenediphenyl diisocyanate) was used as the aromatic diisocyanate, the coating adhesion, ATF resistance and high temperature adhesion were good, but it was confirmed that the peel adhesion was inferior to that of the Examples. In the case of Comparative Examples 5, 8, and 11, in which 4,4'-MDI (4,4-methylenediphenyl diisocyanate) was used as the aromatic diisocyanate, the coating adhesion and high-temperature adhesion were good, but it was confirmed that the peel adhesion and ATF resistance properties were inferior to those of the Examples.

[0070] Comparative Example 12 is an example in which polypropylene glycol was used as the polyol compound. Although the coating adhesion, peel adhesion strength, and ATF resistance properties were good, it was confirmed that the high-temperature adhesion strength was deteriorated. 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, it should be understood that the above-described examples are illustrative in all respects and not limiting. [Explanation of symbols]

[0071] 10 Electrical steel sheet 20 Fusion layer 100 electromagnetic steel sheet laminate,

Claims

1. It contains a mixed resin of urethane resin and epoxy resin, The urethane resin comprises repeating units represented by the following formula 1 and formula 2: 【Chemistry 1】 【Chemistry 2】 (In the above Chemical Formula 1 and Chemical Formula 2, R １ L each independently represents 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, a hydroxy group, or a halogen atom. １ , L ２ , L ３ represents a single bond or a divalent linking group, and n represents an integer of 1 to 50.

2. 2. The adhesive coating composition for an electrical steel sheet according to claim 1, wherein the urethane resin is present in an amount of 20 to 80 parts by weight and the epoxy resin is present in an amount of 20 to 80 parts by weight, based on 100 parts by weight of the mixed resin.

3. 2. The adhesive coating composition for an electrical steel sheet according to claim 1, wherein the urethane resin comprises repeating units represented by the following Formula 3 and Formula 2: 【Transformation 3】 (In the above chemical formula 3, R １ L each independently represents 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, a hydroxy group, or a halogen atom. １ represents a single bond or a divalent linking group.

4. 2. The adhesive coating composition for electrical steel sheets according to claim 1, wherein the urethane resin is formed by reacting a diisocyanate monomer with a polyol represented by the following chemical formula 4: 【Chemistry 4】 (In the above chemical formula 4, L ２ , L ３ represents a single bond or a divalent linking group, and n represents an integer of 1 to 50.

5. The electrical steel sheet adhesive coating composition according to claim 4 , wherein the diisocyanate monomer comprises an aromatic diisocyanate monomer.

6. 6. The adhesive coating composition for electrical steel sheets according to claim 5, wherein the aromatic diisocyanate monomer is a compound represented by the following chemical formula 5: 【Transformation 5】 (In the above chemical formula 5, R １ ~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, a hydroxy group, a halogen element, or an isocyanate group; At least one of R1 to R5 is an isocyanate group, At least one of R6 to R10 is an isocyanate group, The case where R3 and R8 are simultaneously an isocyanate group is excluded. 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.

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

8. 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.

9. 9. The adhesive coating composition for electrical steel sheets according to claim 8, 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.

10. 9. The adhesive coating composition for electrical steel sheets according to claim 8, 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.

11. 9. The adhesive coating composition for electrical steel sheets according to claim 8, 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.

12. 9. The adhesive coating composition for electrical steel sheets according to claim 8, 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.

13. A plurality of electromagnetic steel sheets; a bonding layer located between the plurality of electrical steel sheets, the fusion layer contains a mixed resin of a urethane resin and an epoxy resin, The urethane resin contains repeating units represented by the following chemical formula 1 and the following chemical formula 2. 【Chemistry 1】 【Chemistry 2】 (In the above Chemical Formula 1 and Chemical Formula 2, R １ L each independently represents 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, a hydroxy group, or a halogen atom. １ , L ２ , L ３ represents a single bond or a divalent linking group, and n represents an integer of 1 to 50.

14. The electromagnetic steel sheet laminate according to claim 13, wherein the fusion layer contains 20 to 80 parts by weight of the urethane resin and 20 to 80 parts by weight of the epoxy resin, based on 100 parts by weight of the mixed resin.

15. applying the adhesive coating composition of claim 1 to one or both sides of an electrical steel sheet and curing the composition to form an adhesive coating layer; a step of laminating a plurality of the magnetic steel sheets having the adhesive coating layer thereon and heat-sealing the laminate to form a fusion layer.

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