Adhesive resin composition coated electrical steel sheet and method for manufacturing the same

Abstract

The present invention provides an adhesive resin composition coated electrical steel sheet that can prevent adhesive blocking and deterioration of adhesive performance even when stored for a long period of time after adhesive application and drying, and that can cure the adhesive resin composition coating in a short time during the heat-compression bonding process when manufacturing the iron core. [Solution] An adhesive resin composition coated electromagnetic steel sheet having an adhesive resin composition coating on at least one surface of the steel sheet, wherein the adhesive resin composition coating is a semi-cured product of an adhesive resin composition comprising an adhesive resin and a curing agent, at least in part of which is a thermosetting resin, the maximum penetration λ of the adhesive resin composition coating at 100 to 300°C measured by thermomechanical analysis as described in JIS K 7196:2012 is 3% or more and less than 100%, a portion of the curing agent is present in the adhesive resin composition coating in a crystalline state, and the depolarized light scattering intensity I of the adhesive resin composition coating is 1.00 × 10⁻⁶ 7 ~50.00 x 10 7 This is an electrical steel sheet coated with an adhesive resin composition.

Description

[Technical Field]

[0001] The present invention relates to an adhesive resin composition-coated electrical steel sheet and a method for manufacturing the same. [Background technology]

[0002] The iron cores used in motors and other applications are assembled by punching out electrical steel sheets into a predetermined shape, shearing them, laminating them, and then fixing them together. A known fixing method involves using a thermosetting adhesive, which allows for fixing without causing processing or thermal distortion, insulates the laminated steel sheets to increase eddy current resistance and reduce iron loss, and also exhibits excellent heat resistance in actual operating environments.

[0003] A common method for laminating and fixing electrical steel sheets with thermosetting adhesives is to punch and shear the sheets before laminating and heat-pressing them. Furthermore, methods for applying thermosetting adhesives to the surface of electrical steel sheets can be broadly divided into two categories based on the timing of adhesive application.

[0004] One method involves applying a thermosetting adhesive to the electrical steel sheet after punching. This method can be further divided into two types: one in which the thermosetting adhesive is sprayed onto the surface of the electrical steel sheet immediately before shearing, followed by shearing and lamination; and another in which, after punching, shearing, and lamination are completed, the laminated core is immersed in adhesive solution to allow it to penetrate between the laminated electrical steel sheets.

[0005] The other method involves applying and drying a thermosetting adhesive to at least one surface of the electrical steel sheet beforehand, then punching and shearing it, and finally laminating it. Hereinafter, an electrical steel sheet having an adhesive resin composition coating, obtained by applying and drying a thermosetting adhesive to at least one surface of the electrical steel sheet, may be referred to as an "adhesive resin composition coated electrical steel sheet."

[0006] Among the methods for laminating and bonding these electrical steel sheets, the latter has been attracting attention in recent years because it is superior in terms of adhesive application handling, uniformity, and productivity.

[0007] In the latter method, first, an adhesive resin composition coated electromagnetic steel sheet (semi-finished product) is obtained, which has a semi-cured adhesive resin composition coating on the surface of the electromagnetic steel sheet, with the curing reaction of the thermosetting adhesive stopped midway. Then, an iron core (finished product) is manufactured using this. The adhesive resin composition coated electromagnetic steel sheet is manufactured by applying and heating a thermosetting adhesive, which is based on a mixture of thermosetting adhesive resin and a curing agent, to the surface of a wide electromagnetic steel sheet. The manufactured adhesive resin composition coated electromagnetic steel sheet is wound into a coil and stored. Furthermore, the adhesive resin composition coated electromagnetic steel sheet may be unwound from the coil, slit to the punching width, wound into a coil again, and stored again.

[0008] The core is manufactured by punching out, shearing, laminating, and heat-pressing electrical steel sheets coated with an adhesive resin composition. Therefore, not only is a technique required to uniformly coat the surface of the steel sheet with the adhesive resin composition, but also a technique to prevent defects such as poor separation of the steel sheets when winding or unwinding the steel sheets into a coil, and insufficient adhesive strength after heat-pressing.

[0009] It is important to note that, generally, the processes from the application of thermosetting adhesive to the heat-compression bonding during the manufacture of the core are not continuous. Therefore, the manufacturing process of adhesive-coated electrical steel sheets (semi-finished products) includes storage and transportation between the completion of drying and the start of die-cutting. Furthermore, the storage period can be very long, sometimes several months or more. In addition, the steel sheets may be stored for several weeks in the cargo hold of a ship, where the temperature can reach around 50°C and the environment is humid. During this storage period, the adhesive-coated electrical steel sheet is in a semi-cured state (non-equilibrium state) where the irreversible curing reaction has been stopped midway.

[0010] Therefore, electrical steel sheets coated with adhesive resin composition are very unstable. Consequently, if stored for a long period of time in a high-temperature, humid environment after adhesive application and drying, defects such as (A) and (B) below are likely to occur. Note that a high-temperature, humid environment refers to, for example, the environment inside the warehouse of a ship sailing near the equator, where the storage temperature is around 50°C. (A) Subsequent blocking: During the storage period, the curing reaction of the adhesive resin proceeds between the surfaces of the adhesive resin composition film, and the laminated steel plates are adhesively joined. (B) Decrease in adhesion ability: During the storage period, the curing of the adhesive resin composition film proceeds excessively. As a result, even when heated for thermocompression bonding, the adhesive resin does not soften sufficiently, and the adhesive resin cannot penetrate into the unevenness of the adherent surface, so the anchor effect cannot be exhibited, and the adhesion ability between the laminated steel plates decreases.

[0011] Therefore, a technique for controlling the curing state of the adhesive resin to solve the instability has been disclosed. Patent Document 1 discloses a technique of coating an electromagnetic steel sheet with an adhesive resin having a Tg (glass transition temperature) or softening temperature of 60°C or higher of the adhesive resin that coats the electromagnetic steel sheet. By vitrifying the adhesive resin near room temperature, stickiness on the surface of the adhesive layer can be prevented, and adhesive blocking can be prevented. This technique is effective when manufacturing a core by punching and thermocompression bonding the adhesive resin composition-coated electromagnetic steel sheet immediately after drying.

[0012] In addition, Patent Documents 2 to 4 disclose a technique of using a latent curing agent as a curing agent for a thermosetting resin to suppress the curing reaction at room temperature. Here, the latent curing agent is, for example, a curing agent that imparts latency to the curing agent, as also explained in Non-Patent Document 1. Due to the latency of the curing agent, the reaction at room temperature can be suppressed, and by giving an external stimulus trigger such as heat, light, moisture, pressure, etc., the curing reaction of the thermosetting resin can be rapidly advanced.

[0013] Furthermore, Patent Documents 5 to 6 suggest that blocking during storage can be prevented by coating an electromagnetic steel sheet with an adhesive resin cured with a latent curing agent.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Patent Document 2

[0015] [Non-Patent Document 1] Journal of the Adhesion Society of Japan, vol.53, No.4(2017), pp.122-128 [Overview of the Initiative] [Problems that the invention aims to solve]

[0016] However, Patent Document 1 does not disclose a method for suppressing the curing reaction of adhesive resin composition-coated electrical steel sheets during storage. The method in Patent Document 1 may cause adhesion-induced blocking in the general manufacturing of adhesive resin composition-coated steel sheets that are stored for long periods, and may also reduce the adhesive performance during heat compression bonding.

[0017] Patent documents 2 to 4 disclose techniques for minimizing the reaction between the resin and the hardener in the adhesive liquid before application to the steel sheet and maintaining a viscosity that facilitates application even during storage of the adhesive (stabilization of adhesive liquid storage and extension of pot life). However, they do not disclose the stability of the adhesive resin in electrical steel sheets coated with the adhesive resin composition after passing through a heating process due to drying.

[0018] Patent documents 5 and 6 do not disclose the state of the latent curing agent in the adhesive resin after heat drying. Curing agents that have been heated once during the drying process often change state and lose their latent properties. Therefore, if the state of the latent curing agent in the adhesive resin composition film after drying is not controlled, it is difficult to suppress the progress of the curing reaction during storage, which can lead to adhesion-induced blocking and a decrease in adhesive ability.

[0019] Furthermore, the diffusion of the curing agent into the adhesive resin and its reaction with the adhesive resin, which occur on the order of several months at room temperature, often correspond to a matter of minutes at the curing temperature. Therefore, if the diffusion rate of the curing agent into the adhesive resin, or the reaction rate with the adhesive resin, is reduced in the adhesive resin composition coating of an adhesive resin composition coated electrical steel sheet, the curing rate in the thermocompression bonding process when manufacturing iron cores using this material will also decrease, sometimes leading to a reduction in the productivity of the iron cores.

[0020] As mentioned above, generally, the manufacturing process from the application of thermosetting adhesive when producing adhesive resin composition coated electrical steel sheets (semi-finished products) to the thermocompression bonding when producing iron cores (finished products) is not continuous. Therefore, during the period from obtaining the adhesive resin composition coated electrical steel sheet (from the completion of adhesive drying) to the start of punching, the adhesive resin composition coating is stored in a semi-cured (non-equilibrium) state in which the irreversible curing reaction is stopped midway. As a result, preventing blocking and deterioration of adhesive ability during the storage period (especially during long-term storage) has been a challenge. In addition, in the thermocompression bonding process when producing iron cores using adhesive resin composition coated electrical steel sheets, it was also necessary to be able to cure in a short time and produce iron cores efficiently.

[0021] This invention has been made in view of these circumstances, and aims to provide an adhesive resin composition coated electromagnetic steel sheet that can prevent adhesive blocking and deterioration of adhesive ability even when stored for a long period of time after adhesive application and drying, and that can cure the adhesive resin composition coating in a short time during the heat compression bonding process when manufacturing the iron core. [Means for solving the problem]

[0022] This invention was made to solve the above problems, and its gist is the following adhesive resin composition-coated electrical steel sheet and method for manufacturing the same.

[0023] (1) An adhesive resin composition coated electrical steel sheet having a steel sheet and an adhesive resin composition coating on at least one surface of the steel sheet, The aforementioned adhesive resin composition coating is a semi-cured product of an adhesive resin composition comprising an adhesive resin and a curing agent, at least in part, which include a thermosetting resin. The maximum penetration λ of the adhesive resin composition coating at 100-300°C, as measured by thermomechanical analysis as described in JIS K 7196:2012, is 3% or more and less than 100%. A portion of the curing agent is present in the adhesive resin composition film in a crystalline state. The depolarized light scattering intensity I of the adhesive resin composition coating is 1.00 × 10 7 ~50.00 x 10 7 That is, Adhesive resin composition coated electrical steel sheet.

[0024] (2) The depolarized light scattering intensity I of the adhesive resin composition coating is 1.20 × 10 7 ~18.00 x 10 7 That is, Electrical steel sheet coated with the adhesive resin composition described in (1) above.

[0025] (3) The softening onset temperature Tss of the adhesive resin composition coating, as measured by thermomechanical analysis as described in JIS K 7196:2012, is 50°C or higher, and the maximum penetration λ at 100-300°C is 15% or higher. Electromagnetic steel sheet coated with the adhesive resin composition described in (1) or (2) above.

[0026] (4) The thermosetting resin comprises one or more selected from epoxy resin, acrylic resin, urethane resin and unsaturated polyester resin. An electrical steel sheet coated with an adhesive resin composition as described in any of (1) to (3) above.

[0027] (5) The curing agent comprises one or more selected from amine-based curing agents, amide-based curing agents, and imidazole-based curing agents. An electrical steel sheet coated with an adhesive resin composition as described in any of (1) to (4) above.

[0028] (6) A method for manufacturing an electrical steel sheet coated with an adhesive resin composition as described in any of (1) to (4) above, A coating step of applying a liquid thermosetting adhesive containing the adhesive resin and the curing agent to at least one surface of the steel plate, The process includes a heating, drying, and solidification step in which the steel plate to which the thermosetting adhesive has been applied is heated, then cooled to form an adhesive resin composition film on the surface of the steel plate. The heating temperature in the aforementioned heating, drying, and solidification step is a temperature T within the temperature range of 100 to 250°C. The heating time in the aforementioned heating, drying, and solidification step satisfies the following equation (i): A method for manufacturing an electrical steel sheet coated with an adhesive resin composition. 0.8 ≤ t / t0 ≤ 18.0 ···(i) However, the meaning of each symbol in equation (i) above is as follows: t: Heating time in the heating, drying, and solidification step. t0: The time required to form an adhesive resin composition film with a softening start temperature of 50°C when the thermosetting adhesive is dried at the temperature T.

[0029] (7) Glass transition temperature Tg of the adhesive resin uc The temperature is 30℃ or higher. The heating temperature in the aforementioned heating, drying, and solidification step is a temperature T within the range of 100 to 190°C. The heating time in the aforementioned heating, drying, and solidification step satisfies the following equation (ii): A method for manufacturing an electrical steel sheet coated with the adhesive resin composition described in (6) above. 1.3 ≤ t / t0 ≤ 15.0 ···(ii) However, the meaning of each symbol in equation (ii) above is as follows: t: Heating time in the heating, drying, and solidification step. t0: The time required to form an adhesive resin composition film with a softening start temperature of 50°C when the thermosetting adhesive is dried at the temperature T.

[0030] (8) The adhesive resin contains 50% by mass or more of a thermosetting resin, which is one or more selected from epoxy resin, acrylic resin, urethane resin, and unsaturated polyester resin, relative to the total amount of the adhesive resin. A method for manufacturing an electrical steel sheet coated with the adhesive resin composition described in (6) or (7) above.

[0031] (9) The curing agent comprises one or more selected from amine-based curing agents, amide-based curing agents, and imidazole-based curing agents. Any of the above (6) through (8) A method for manufacturing an electrical steel sheet coated with the adhesive resin composition described above. [Effects of the Invention]

[0032] According to the present invention, an adhesive resin composition coated electrical steel sheet can be obtained that prevents adhesive blocking and deterioration of adhesive performance even when stored for a long period of time after adhesive application and drying, and that allows the adhesive resin composition coating to harden in a short time when heat-pressed. [Brief explanation of the drawing]

[0033] [Figure 1] This diagram illustrates a method for measuring the depolarized light scattering intensity I of an adhesive resin composition coating. [Figure 2] This figure illustrates a method for analyzing the softening onset temperature Tss and maximum penetration depth λ of an adhesive resin composition coating. [Modes for carrying out the invention]

[0034] The details of the present invention will be described below in the order of the focus, specific embodiments based thereon, and methods of use. However, the description of the constituent elements described below is just one example (representative example) of an embodiment of the present invention, and the present invention is not limited to the following unless its gist is changed.

[0035] <The key concept of this invention> (Control Guidelines) To solve the above problems, the inventors conducted the following studies.

[0036] When steel sheets coated with an adhesive resin composition are stored for a long period (e.g., several months) in a high-temperature, humid environment, the curing agent diffuses into the adhesive resin within the adhesive resin composition coating, and a slow curing reaction (hereinafter referred to as "slow curing reaction") proceeds within the coating. Therefore, if the slow curing reaction within the adhesive resin composition coating during storage is not suppressed, it is difficult to prevent adhesive blocking and a decrease in adhesive performance due to excessive curing of the adhesive resin composition coating. On the other hand, if the reaction rate of the curing reaction of the adhesive resin composition coating is too slow, the curing reaction will not proceed quickly during thermocompression bonding. As a result, the productivity of the iron core decreases.

[0037] Therefore, the inventors focused on and investigated the following points in order to prevent adhesive blocking and deterioration of adhesive performance during storage.

[0038] 1) Elementary processes of the slow hardening reaction First, the slow curing reaction within the adhesive resin coating of an adhesive resin-coated electrical steel sheet during storage can be broken down into the following three elementary processes. (a) Dissolution of the hardening agent (b) Diffusion of the curing agent into the adhesive resin (c) Collision and reaction of the curing agent with the adhesive resin molecules

[0039] Therefore, in order to suppress the progress of the slow curing reaction within the adhesive resin composition coating during storage of electrical steel sheets coated with adhesive resin composition, it is necessary to reduce either the dissolution rate, diffusion rate, or reaction activity of the curing agent.

[0040] In view of the following points, the present invention suppresses the dissolution of the curing agent in (a) and inhibits the slow curing reaction. Specifically, the slow curing reaction is inhibited by using a curing agent that crystallizes at least partially at room temperature, and by leaving a certain amount of the crystalline curing agent (hereinafter sometimes referred to as "curing agent crystals") in the adhesive resin composition coating.

[0041] First, focusing on (b) and (c), the disadvantages of suppressing the slow hardening reaction are as follows: To suppress the slow curing reaction within the adhesive resin composition film by inhibiting the diffusion of the curing agent in (b) into the adhesive resin and the collision and reaction of the curing agent in (c) with the adhesive resin molecules, it is necessary to suppress the thermal mobility of the adhesive resin phase molecules and increase the activation energy of the curing reaction at room temperature, respectively. However, the former requires raising the crystallization temperature or glass transition temperature (Tg) of the adhesive resin. As a result, the diffusion of the curing agent slows down even during thermocompression bonding, requiring thermocompression bonding at higher temperatures. Furthermore, in the latter case, the curing reaction rate of the adhesive resin composition film during thermocompression bonding also slows down in many cases, impairing the productivity of the iron core.

[0042] On the other hand, focusing on (a), the advantages of leaving a certain amount of hardener in a crystalline state are as follows: The dissolution of the curing agent in (a) can be controlled by the change in the state of the curing agent, and since the crystallization and dissolution states of the curing agent are thermodynamically reversible, if heating and cooling are performed appropriately during heating, drying, and solidification, crystals can be precipitated even if they dissolve due to heating. Furthermore, the crystallized curing agent can stably exist in the adhesive resin composition film without dissolving at room temperature. Therefore, if a certain amount of curing agent remains in a crystalline state in the adhesive resin composition film coated on the electrical steel sheet, the slow curing reaction can be stably suppressed. In addition, since solubility can be controlled independently of the thermal mobility and reaction activity of the adhesive resin phase molecules, even if the aforementioned controls are applied to these for short-time curing in the thermocompression bonding process, the slow curing reaction can be stably suppressed during storage.

[0043] Next, specific embodiments will be described.

[0044] <Adhesive resin composition coated electrical steel sheet> The present invention relates to an adhesive resin composition coated electrical steel sheet having an adhesive resin composition coating on at least one surface of a steel sheet, wherein the adhesive resin composition coating is a semi-cured product of an adhesive resin composition comprising an adhesive resin containing at least a portion of a thermosetting resin and a curing agent, the maximum penetration λ of the adhesive resin composition coating at 100 to 300°C measured by thermomechanical analysis as described in JIS K 7196:2012 is 3% or more and less than 100%, a portion of the curing agent is present in the adhesive resin composition coating in a crystalline state, and the depolarized light scattering intensity I of the adhesive resin composition coating is 1.00 × 10⁻⁶ 7 ~50.00 x 10 7 This invention relates to an adhesive resin composition-coated electrical steel sheet (hereinafter sometimes referred to as "the adhesive resin composition-coated electrical steel sheet of the present invention").

[0045] With this configuration, the following effects can be obtained during storage and during the heat-pressing process of the electrical steel sheet coated with the adhesive resin composition of the present invention.

[0046] The following effects can be obtained during storage: • Prevention of reduced adhesive strength and adhesive blocking: Since a certain amount of curing agent is present in the adhesive resin composition coating in a crystalline state that is difficult to dissolve in the adhesive resin, the dissolution of the curing agent into the adhesive resin can be suppressed during the storage period of the adhesive resin composition coated electrical steel sheet. As a result, diffusion and movement of the curing agent can be suppressed within the adhesive resin composition coating, at the interface between the adhesive resin composition coating and the steel sheet, and at the interfaces between adhesive resin composition coatings when adhesive resin composition coated electrical steel sheets are stacked, such as by winding them into a coil. This suppresses slow curing reactions within the adhesive resin composition coating during storage, as well as reactions between the adhesive resin composition coating and the adherend, thereby preventing a decrease in adhesive performance and adhesive blocking.

[0047] The following effects can be obtained in the heat-pressing process. • Rapid curing of the adhesive resin composition film during heat-press bonding: By dissolving the curing agent that remains in a crystalline state during storage during thermal bonding, diffusion into the adhesive resin is promoted, enabling the curing of the adhesive resin composition film in a short time. Furthermore, maintaining the crystalline state inhibits the dissolution of the curing agent, thereby suppressing the slow curing reaction within the adhesive resin composition film during storage. Therefore, it is possible to use this product in combination with a catalyst and / or accelerator that promotes the reaction activation energy. By adding these, it may be possible to achieve both the rapid curing of the adhesive resin composition film during thermal bonding and the suppression of the slow curing reaction within the adhesive resin composition film during the storage period of the adhesive resin composition coated electrical steel sheet. Furthermore, the use of catalysts and / or accelerators to enhance the reaction activation energy is not essential.

[0048] [Steel plate] The steel sheet (sometimes referred to as "electromagnetic steel sheet") excluding the adhesive resin composition coating in the adhesive resin composition coated electromagnetic steel sheet of the present invention is not particularly limited and any known steel sheet can be used.

[0049] [Adhesive resin composition film] The adhesive resin composition coating is a layer formed on at least one surface of a steel sheet, and is a semi-cured product of an adhesive resin composition consisting of an adhesive resin and a curing agent. Since the adhesive resin composition coating, which consists of a semi-cured product of a thermosetting adhesive resin composition, can exhibit adhesive properties by heating and pressurizing, adhesive resin composition coated electromagnetic steel sheets can be bonded to each other by laminating them and heat-pressing them together.

[0050] [Adhesive resin composition] The adhesive resin composition consists of an adhesive resin containing at least a portion of a thermosetting resin and a curing agent. The adhesive resin composition in the adhesive resin composition coating is in a semi-cured state in which partial curing has progressed.

[0051] [Adhesive resin] Adhesive resins exhibit thermosetting properties and therefore contain at least a portion of a thermosetting resin. As described above, an adhesive resin composition consists of an adhesive resin containing at least a portion of a thermosetting resin and a curing agent. Therefore, the term "adhesive resin" refers to the component of the adhesive resin composition excluding the curing agent (unreacted curing agent). Thermosetting resins are resins that harden upon heating during use, sometimes with the added action of a catalyst, by crosslinking a three-dimensional polymer. In the adhesive resin composition coating, a portion of the thermosetting resin has crosslinked with the curing agent, while the remainder exists in an unreacted state.

[0052] [Hardening agent] The curing agent contained in the adhesive resin composition is a compound that reacts with functional groups contained in the thermosetting resin to form a three-dimensional structure and cure the adhesive resin composition, and at least a portion of it crystallizes at room temperature. That is, a portion of the curing agent exists in a crystalline state in the adhesive resin composition film. The curing agent used in the present invention only needs to include a curing agent that can crystallize at room temperature and in which a portion of it can exist in a crystalline state in the adhesive resin composition film. Either only a curing agent that can crystallize at room temperature is used, or a curing agent that can crystallize at room temperature and a curing agent that does not crystallize at room temperature are used in combination. Note that the curing agent in the adhesive resin composition film refers to the unreacted curing agent component that has not reacted with the thermosetting resin.

[0053] In this invention, whether or not a portion of the curing agent is present in a crystalline state within the adhesive resin composition coating is determined using a polarizing microscope. Since the curing agent crystals are optically anisotropic, they appear bright when observed through a polarizing filter arranged in crossed nicols. On the other hand, the adhesive resin is optically isotropic, so it appears dark. Therefore, by using this difference, the adhesive resin phase, which mainly consists of the adhesive resin other than the curing agent crystals, can be separated from the curing agent crystals. Specifically, the adhesive resin composition coating covering the steel plate is observed with a polarizing microscope in a cross section parallel to the surface of the steel plate. More specifically, as polarizing microscopes, examples include the Olympus BX53M or the Nikon LV150N upright microscope.

[0054] Set a polarizing filter (for example, U-AN360-3, U-POTP3 manufactured by Olympus Corporation, etc.) in a cross Nicol and observe it at 100 to 800 times magnification. Note that the magnification can be appropriately selected within this range according to the ease of identifying the curing agent crystal image. And when a bright phase is observed, it is determined that a part of the curing agent exists in the adhesive resin composition film in a crystalline state.

[0055] [Semi-cured product] The adhesive resin composition for forming the adhesive resin composition film is a semi-cured product in which curing has partially progressed. A semi-cured product is a state in which the curing of the adhesive resin composition has not progressed to 100%. In the present invention, whether it is in a semi-cured state is determined using the maximum penetration described later as an index. Specifically, if the maximum penetration measured by thermomechanical analysis described in JIS K 7196:2012 is 3% or more and less than 100%, it is determined to be in a semi-cured state.

[0056] [Amount of curing agent in crystalline state in adhesive resin composition film] The electromagnetic steel sheet coated with the adhesive resin composition of the present invention contains a certain amount of a curing agent (curing agent crystal) in a crystalline state in the adhesive resin composition film. The appropriate range of the residual amount of the curing agent crystal in the adhesive resin composition film can be defined by the light scattering intensity using the optical anisotropy of the curing agent crystal, that is, the depolarized light (Hv) scattering intensity I. In the electromagnetic steel sheet coated with the adhesive resin composition of the present invention, the depolarized light scattering intensity (light quantity) I of the adhesive resin composition film is 1.00×10 7 ~50.00×10 7 is.

[0057] Here, the depolarized light scattering intensity I of the adhesive resin composition film is the measured value I0 (integrated value of the light quantity from a scattering angle of 0° to 22°) of the depolarized light scattering intensity of a 0.15 mm thick cover glass (for example, cover glass No. 1 manufactured by Matsunami Glass Industry Co., Ltd.) ultrasonically cleaned with a detergent for 5 minutes or more, and the measured value I1 of the depolarized light scattering intensity of the adhesive resin composition film is normalized by I0, that is, I = I1 / I0.

[0058] When the depolarized light scattering intensity I is 1.00×107 If the value is less than 50.00 × 10⁻¹⁰, most of the curing agent will dissolve and diffuse, failing to suppress the slow curing reaction during storage, and preventing the adhesive resin composition film from curing quickly during heat bonding. On the other hand, if the depolarized light scattering intensity I is 50.00 × 10⁻¹⁰, then most of the curing agent will dissolve and diffuse, failing to suppress the slow curing reaction during storage, and preventing the adhesive resin composition film from curing quickly during heat bonding. 7 In the case of excessive curing agent, the reaction rate of the curing reaction of the adhesive resin composition film is too slow, preventing the curing reaction from progressing quickly during thermal bonding. Furthermore, if excess curing agent is added, the depolarized light scattering intensity I becomes excessive, which may reduce the strength and toughness of the adhesive resin composition film.

[0059] From the viewpoint of ensuring resistance to adhesive blocking and achieving rapid curing, the depolarized light scattering intensity I of the adhesive resin composition coating is set to 1.05 × 10⁻⁶. 7 ~25.00 x 10 7 Preferably, 1.20 × 10 7 ~18.00 x 10 7 This is preferable.

[0060] The depolarized light scattering intensity I of an adhesive resin composition coating can be measured by peeling the adhesive resin composition coating from a steel plate and using a known light scattering intensity measurement method, specifically a light scattering measurement device equipped with a CCD camera that can set a polarizing filter in crossed nicols using a He-Ne laser (λ=632.8nm) as the light source (for example, the PP-1000 manufactured by Otsuka Electronics Co., Ltd.). Figure 1 is a diagram illustrating the method for measuring the depolarized light scattering intensity I of an adhesive resin composition coating. As shown in Figure 1, the adhesive resin composition coating, which is the sample, is set between the light-emitting polarizing filter and the light-receiving polarizing filter, and the amount of light at a predetermined scattering angle (θ) can be measured by adjusting the distance (L) between the sample and the two-dimensional detector (CCD camera).

[0061] One specific method for removing the adhesive resin composition coating from a steel sheet is to immerse the coated electrical steel sheet in a liquid that dissolves the steel sheet, such as an acid like hydrochloric acid or nitric acid, or an alkaline solution like sodium hydroxide, adjusted to a concentration that does not affect the adhesive resin composition coating. This dissolves the steel sheet and peels the adhesive resin composition coating from the surface. Alternatively, the coating may be removed by mechanically cutting the steel sheet. Here, "affecting the adhesive resin composition coating" refers to altering the coating by dissolving the hardener crystals or decomposing the adhesive resin. However, the method is not limited to these, as long as it can be removed without affecting the adhesive resin composition coating as described above.

[0062] Given the components and composition of the adhesive resin composition coating, as well as the conditions for the application and heat-drying / solidification process on the steel plate, a cast film of the adhesive resin composition may be prepared with the same thickness as the steel plate coating and subjected to the same amount of heat input as in the heat-drying / solidification process, and the depolarized light scattering intensity I of this cast film may be used as a substitute.

[0063] [Softening onset temperature Tss and maximum penetration depth λ] The adhesive resin composition coating preferably has a softening onset temperature Tss of 50°C or higher, measured in the penetration mode of a thermomechanical analyzer (TMA) in accordance with JIS K 7196:2012, and a maximum penetration degree λ of 15% or higher at 100-300°C. An adhesive resin composition coating that satisfies such a softening onset temperature and maximum penetration degree λ is in a moderately cured state and provides the following effects.

[0064] By setting the softening start temperature Tss to 50°C or higher, adhesive blocking during storage of the resulting adhesive resin composition-coated electrical steel sheet can be prevented, further enhancing the effects of suppressing adhesive blocking and preventing a decrease in adhesive performance. The upper limit of the softening start temperature Tss is not particularly limited, but 100°C or lower is preferred. If the softening start temperature Tss exceeds 100°C, the adhesive resin composition coating remains hard even in a semi-cured state, which can slow the diffusion rate of the curing agent into the adhesive resin during the heat-compression bonding process, making short-time curing difficult. Alternatively, heat-compression bonding at high temperatures exceeding 250°C may be required during the heat-compression bonding process, leading to prolonged heating and cooling and reduced productivity.

[0065] By setting the maximum penetration depth λ to 15% or more, excessive hardening of the adhesive resin composition coating can be further prevented, resulting in an adhesive resin composition coating that is easier to soften during heat bonding.

[0066] To sufficiently soften the adhesive resin composition film during heat bonding, the maximum penetration degree λ is preferably 30% or more, more preferably 60% or more. Furthermore, if the maximum penetration degree λ exceeds 95%, the degree of curing of the adhesive resin composition film is too low, the adhesive resin composition film becomes soft, and the adhesive resin composition may flow out during heat bonding. Therefore, it is desirable to set the upper limit of the maximum penetration degree λ to 95% or less, more preferably 80% or less.

[0067] Therefore, the adhesive resin composition coating preferably has a maximum penetration degree λ of 15 to 95% and a softening start temperature Tss of 50 to 100°C, more preferably has a maximum penetration degree λ of 30 to 90% and a softening start temperature Tss of 50 to 100°C, and even more preferably has a maximum penetration degree λ of 60 to 80% and a softening start temperature Tss of 50 to 100°C.

[0068] Here, the softening initiation temperature Tss and the maximum penetration depth λ will be explained. Figure 2 is a diagram illustrating the analysis method for the softening initiation temperature Tss and the maximum penetration depth λ of an adhesive resin composition coating. The TMA curve shown in Figure 2 is a typical TMA curve of an adhesive resin composition coating in the present invention. The TMA curve can be obtained by measuring the adhesive resin composition coating that covers the steel plate, except for measuring the TMA curve itself, according to the method of JIS K 7196:2012. The softening initiation temperature Tss is defined in the TMA curve as shown in Figure 2, at the intersection of a line extended from the low-temperature side of the straight portion below the point where the needle (indenter) begins to penetrate to the high-temperature side, and a line extended from the tangent to the point where the needle penetration speed is maximum to the low-temperature side.

[0069] The maximum penetration depth λ is defined as the percentage of the value obtained by dividing the maximum needle penetration length (μm) by the thickness of the adhesive resin composition coating (μm) ((maximum needle penetration length / thickness of adhesive resin composition coating) × 100). The maximum needle penetration length (μm) can be determined from the TMA curve as shown in Figure 2. The measurement is performed in a 100% N2 atmosphere, with a heating rate of 15°C / min, an applied pressure of 0.6~2.0 MPa, and a tip diameter of 0.5~1.0 mm. The thickness of the adhesive resin composition coating can be measured by cutting a cross-section of the adhesive resin composition coated electrical steel sheet and observing it under a microscope.

[0070] [Glass transition temperature (Tg) of uncured adhesive resin] The glass transition temperature Tg(Tg) of the adhesive resin contained in the uncured, liquid thermosetting adhesive before curing. uc ), preferably 30°C or higher. Tg of the adhesive resin uc If the temperature is below 30°C, depending on the desired softening start temperature of the adhesive resin composition film (glass transition temperature at the start of softening, Tss), a large amount of heat must be input during the heating, drying, and solidification process after applying the adhesive to the steel plate to form an adhesive resin composition film with a desired softening start temperature (e.g., 50°C or higher), thereby curing a considerable amount of the thermosetting adhesive resin composition. To achieve this, it is necessary to dissolve a large portion of the curing agent during heating, drying, and solidification and diffuse it into the adhesive resin composition film, making it difficult to retain a certain amount of curing agent in a crystalline state within the adhesive resin composition film.

[0071] Also, the Tg of the adhesive resin uc The temperature is preferably 80°C or lower. The Tg of the adhesive resin. uc If the temperature exceeds 80°C, the viscosity of the adhesive applied to the steel plate becomes too high, making uniform application difficult.

[0072] Note that the Tg of the adhesive resin uc The composition (components and formulation) of the adhesive resin coating the steel plate can be determined by nuclear magnetic resonance or pyrolysis gas chromatography, and the result can be calculated using the following formula (Fox's formula).

[0073]

number

[0074] Here, ω i This is the mixing ratio (weight ratio) of component i, and Tg i is the glass transition temperature or softening start temperature of component i. Tg of each component i i This can be determined using a differential scanning calorimeter (DSC) or thermomechanical analyzer (TMA) by known Tg or softening onset temperature measurement methods, such as those conforming to JIS K 7121:2012 or JIS K 7196:2012. Alternatively, known values ​​listed in manufacturer catalogs, such as those found at https: / / www.nscm.nipponsteel.com / epoxy / ec.html (as of April 2022), may be used.

[0075] Furthermore, the hardener does not actually vitrify, and the Tg of the adhesive resin uc Because the effect on the Tg of the adhesive resin composition is small, uc Measure the Tg of the adhesive resin and use this to determine the Tg of the adhesive resin. uc This may also be done. The Tg of the adhesive resin composition ucThe composition (components and formulation) of the adhesive resin composition can be determined by nuclear magnetic resonance or pyrolysis gas chromatography, a measurement sample of the same composition is prepared, and the Tg can be determined using a differential scanning calorimeter (DSC) according to the method in accordance with JIS K 7121:2012. The measurement sample can be prepared, for example, by the method described in the examples. Specifically, the adhesive resin composition is diluted with an appropriate solvent to prepare a liquid thermosetting adhesive. This liquid thermosetting adhesive is cast onto a glass plate and then vacuum-dried to produce a cast film. The Tg (intermediate glass transition temperature) is measured using the prepared cast film according to the method in accordance with JIS K 7121:2012, and this is used as the Tg of the adhesive resin composition. uc It can be done.

[0076] [Thermosetting resin] Specific examples of thermosetting resins include cross-linked resins such as epoxy resins, thermosetting acrylic resins, urethane resins, unsaturated polyester resins, phenolic resins, melamine resins, urea resins, and thermosetting polyimide resins. In the present invention, these resins can be used individually or in combination of two or more types.

[0077] [Epoxy resin] Epoxy resins are resins containing two or more epoxy groups, and these resins can be crosslinked with a suitable curing agent to create a three-dimensional structure and then cured. Examples of epoxy resins containing epoxy groups include bisphenol-based (bisphenol A type, bisphenol F type, bisphenol AD ​​type), naphthalene-based, and cardo-based epoxy resins.

[0078] [Thermosetting acrylic resin] Examples of thermosetting acrylic resins include copolymers of acrylic acid esters or methacrylic acid esters with acrylic monomers having reactive functional groups such as hydroxyl groups, amino groups, N-methylol, N-alkoxymethyl carboxide, allyl groups, and epoxy groups. Specifically, examples include copolymers of methyl acrylate or methyl methacrylate with one or more acrylic monomers having reactive functional groups such as acrylic acid, methacrylic acid, acrylamide, N-methylolacrylamide, N-(methoxymethyl)acrylamide, allyl methacrylate, acrylic glycidyl ether, and glycidyl methacrylate. Thermosetting acrylic resins can be crosslinked by utilizing the self-reactivity of reactive functional groups, or by crosslinking and curing through the reaction of reactive functional groups with curing agents such as amines.

[0079] [Urethane resin] Examples of urethane resins include resins composed of polyfunctional isocyanate compounds and residues of hydroxyl group-containing compounds. Specifically, these include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane isocyanate, and polymethylene polyphenylene polyisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate and xylene isocyanate, or mixtures thereof, and resins composed of residues of hydroxyl group-containing compounds such as polyether polyols, polyester polyols, polyacrylate polyols, and polycarbonate polyols. Urethane resins can be crosslinked and cured by reaction with curing agents such as isocyanate-based curing agents or polyol-based curing agents.

[0080] [Unsaturated polyester resin] Examples of unsaturated polyester resins include dehydration condensates of compounds in which unsaturated dibasic acids such as maleic anhydride, fumaric acid, and itaconic acid, or a portion thereof, are substituted with saturated dibasic acids such as phthalic anhydride, isophthalic acid, and terephthalic acid, and compounds in which dihydric alcohols such as ethylene glycol, diethylene glycol, and propylene glycol, or a portion thereof, are substituted with polyhydric alcohols such as glycerin and pentaerythritol. Unsaturated polyester resins can be crosslinked and cured by reaction with curing agents such as isocyanate-based curing agents.

[0081] [Other thermosetting resins] Examples of phenolic resins include resins having two or more phenols (phenol, cresol, etc.) in the resin. For example, resins consisting of residues of phenols and formaldehydes or aldehydes include phenol novolac resins, cresol novolac resins, cresol naphthol formaldehyde polycondensates, and triphenylmethane-type polyfunctional phenyl resins. Phenol aralkyl resins are also included. Examples of melamine resins include alkyl etherified melamine resins and their substituted derivatives. Examples of urea resins include ethylene urea resins. Examples of thermosetting polyimide resins include resins consisting of residues of polycarboxylic acid dianhydrides and diamine compounds. Specifically, thermosetting polyimide resins such as maleimide polymers, bismaleimide polymers, aminobismaleimide polymers, and bismaleimide triazine polymers are included. These resins can also be cured by crosslinking reactions with curing agents.

[0082] [Suitable examples of thermosetting resins] Among the thermosetting resins mentioned above, glass transition temperature Tg ucBecause there are many options for achieving temperatures above 30°C, the curing reaction at high temperatures is rapid, and the dispersion state of the curing agent is easy to manufacture, it is preferable that the thermosetting resin contains one or more selected from the group consisting of epoxy resins, acrylic resins, urethane resins, and unsaturated polyester resins. Among these, from the standpoint of economy, versatility, and handling, it is most preferable that the thermosetting resin contains epoxy resin.

[0083] [Suitable examples of adhesive resins included in thermosetting adhesives] The adhesive resin contains one or more thermosetting resins selected from the group consisting of epoxy resins, acrylic resins, urethane resins, and unsaturated polyester resins, and it is preferable that the total content of these thermosetting resins (total mass of these thermosetting resins / mass of adhesive resin (total amount) × 100 (%)) is 50% by mass or more. Adhesives containing less than 50% by mass of these thermosetting resins may not be able to fully utilize the properties of these thermosetting resins. Among these, adhesive resins containing 50% by mass or more of epoxy resin are most preferred in terms of economy, versatility, and handling.

[0084] The adhesive resin may include a thermosetting resin, and even if it consists of a thermosetting resin, it may also contain organic or inorganic components other than thermosetting resins. For example, it may contain thermoplastic resins; impact modifiers such as core-shell rubber and natural rubber; curing accelerators such as dimethylurea, boron trifluoride, and triphenylphosphine; modifiers for known epoxy resins; reaction control agents (such as catalysts); surfactants; rust inhibitors; lubricants; antioxidants; defoamers; coloring pigments, etc.

[0085] [Examples of hardeners] Examples of curing agents include amine-based, amide-based, imidazole-based, acid anhydride-based, phenol-based, and catalytic curing agents. In the present invention, for example, it is possible to select a crystalline curing agent that crystallizes at room temperature from the following specific examples, either alone or in combination of two or more types.

[0086] [Amine-based curing agent] Examples of amine-based curing agents include, but are not limited to, aliphatic amines, aromatic amines, and guanidine compounds.

[0087] [Aliphatic amines] Examples of aliphatic amines, though not limited to those listed below, include diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, m-xylenediamine, trimethylhexamethylenediamine, 2-methylpentamethylenediamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, 1,2-diaminocyclohexane, benzoylamine, methylcyclohexylamine, and diazabicycloundecene.

[0088] [Aromatic amines] Aromatic amines include, but are not limited to, diaminodiphenylmethane, m-phenylenediamine, diaminodiphenylsulfone (DDS), diethyltoluenediamine, trimethylenebis(4-aminobenzoate), polytetramethylene oxide-di-p-aminobenzoate, methylaniline, and dimethylaniline.

[0089] [Guanidine compounds] Examples of guanidine compounds include, but are not limited to, dicyandiamide (DICY, cyanoguanidine) and its derivatives, methylguanidine, ethylguanidine, propylguanidine, butylguanidine, dimethylguanidine, trimethylguanidine, phenylguanidine, diphenylguanidine, and toluylguanidine.

[0090] [Amid-based hardener] Examples of amide-based curing agents include, but are not limited to, amine-based curing agents to which acid anhydrides have been added, or hydrazide compounds.

[0091] [Hydrazide compounds] Examples of hydrazide compounds include, but are not limited to, succinate dihydrazide, adipic acid dihydrazide, phthalate dihydrazide, isophthalate dihydrazide, terephthalate dihydrazide, p-oxybenzoic acid hydrazide, salicylic acid hydrazide, phenylaminopropionic acid hydrazide, and maleate dihydrazide.

[0092] [Imidazole-based curing agent] Examples of imidazole-based curing agents include imidazole-isocyanuric acid compounds, diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine (2MZ-AZINE), 1-cyanoethyl-2-ethyl-4-methylimidazole (CEMI), 2-ethyl-4-methylimidazole, and 2-undecylimidazole (C 11 Examples include Z).

[0093] [Acid anhydride curing agent] Examples of acid anhydride-based curing agents include, but are not limited to, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0094] [Phenol-based curing agent] Examples of phenolic curing agents include, but are not limited to, phenol novolac resins, cresol novolac resins, phenol aralkyl resins, cresol aralkyl resins, naphthol aralkyl resins, biphenyl-modified phenol resins, biphenyl-modified phenol aralkyl resins, dicyclopentadiene-modified phenol resins, aminotriazine-modified phenol resins, naphthol novolac resins, naphthol-phenol cocondensed novolac resins, naphthol-cresol cocondensed novolac resins, and allyl acrylic phenol resins.

[0095] [Catalytic curing agent] Examples of catalytic curing agents include, but are not limited to, cationic thermosetting catalysts, BF3-amine complexes, and 1,8-diazabicyclo[5.4.0]undeca-7-ene.

[0096] The curing reaction rate of the adhesive resin composition film during heat-pressure bonding is fast, and the short curing time of the adhesive resin composition film is relatively easy to achieve. Therefore, it is preferable that the curing agent contains one or more crystalline curing agents selected from the group consisting of amine-based curing agents, amide-based curing agents, and imidazole-based curing agents. In particular, it is preferable to include one or more crystalline curing agents selected from the group consisting of aromatic amines, guanidine compounds, amide-based curing agents, and imidazole-based curing agents, as this allows for a higher temperature at which the curing reaction of the resin composition film proceeds most easily. By using such curing agents, a difference can be made between the storage temperature of the adhesive resin composition coated electrical steel sheet and the heating temperature during heat-pressure bonding, making it easier to control the heating rate during heat-pressure bonding. For ease of handling and versatility, it is most preferable that the curing agent contains one or more selected from the group consisting of dicyandiamide (DICY), diaminodiphenyl sulfone (DDS), and diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine (2MZ-AZINE).

[0097] Furthermore, the adhesive resin composition coating of the electrical steel sheet coated with the adhesive resin composition of the present invention only requires that the above-mentioned specific amount of curing agent be present in a crystalline state, and the types of adhesive resin and curing agent are not limited to the above examples.

[0098] [Thickness of electrical steel sheet coated with adhesive resin composition] The thickness of the adhesive resin composition-coated electrical steel sheet of the present invention can be, for example, 0.10 mm or more and 0.50 mm or less. This is merely the thickness range of commonly available and known adhesive resin composition-coated electrical steel sheets, and the present invention is also applicable to adhesive resin composition-coated electrical steel sheets outside this range.

[0099] [Film thickness of adhesive resin composition coating] The thickness of the adhesive resin composition coating in the electrical steel sheet coated with the adhesive resin composition of the present invention is not particularly limited, but can be, for example, 2 to 10 μm. If it is less than 2 μm, it cannot penetrate sufficiently into the surface irregularities of the adherend, and the anchoring effect is difficult to exhibit. If it is greater than 10 μm, the volume ratio of the adhesive resin composition coating to the laminated core becomes too large, which may reduce the magnetic properties of the laminated core.

[0100] <Manufacturing method> This invention describes a method for manufacturing an adhesive resin composition-coated electrical steel sheet that is preferable to the adhesive resin composition coating and achieves both good blocking suppression ability and sufficient adhesive ability. However, the manufacturing method for the adhesive resin composition-coated electrical steel sheet of the present invention is not limited to the method described below.

[0101] The present invention provides a method for manufacturing an adhesive resin composition-coated electrical steel sheet, comprising: an adhesive application step of applying a liquid thermosetting adhesive containing an adhesive resin and a curing agent to at least one surface of a steel sheet; and a heat drying and solidification step of heating the steel sheet coated with the thermosetting adhesive and then cooling it to form an adhesive resin composition film on the surface of the steel sheet.

[0102] [Adhesive application process] The adhesive application process involves applying a liquid thermosetting adhesive, which contains an adhesive resin and a curing agent, to at least one surface of the steel plate.

[0103] [Thermosetting adhesive] A thermosetting adhesive that can be used in the manufacture of electrical steel sheets coated with an adhesive resin composition is a liquid substance containing an adhesive resin and a curing agent. Depending on the composition of the adhesive resin composition film (semi-cured product) to be formed, in addition to the thermosetting resin and curing agent, it may also contain a thermoplastic resin; an impact modifier such as core-shell rubber or natural rubber; a curing accelerator such as dimethylurea, boron trifluoride, or triphenylphosphine; a known epoxy resin modifier; a reaction control agent (such as a catalyst); a surfactant; a rust inhibitor; a lubricant; an antioxidant; an antifoaming agent; a coloring pigment, etc.

[0104] Thermosetting adhesives can be used as is if the adhesive resin composition constituting the adhesive resin composition film is in an uncured, liquid state. However, if it is not liquid, or if the viscosity needs to be adjusted, a solvent is added to create a liquid composition containing the adhesive resin composition and the solvent. Suitable solvents include aromatic hydrocarbon solvents such as benzene, toluene, and xylene; alicyclic hydrocarbon solvents such as cyclohexane; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone (anone), and tetrahydrofuran (THF); and halogenated solvents such as methylene chloride, dichloroethane, and chloroform.

[0105] Thermosetting adhesives can be used as a liquid consisting of an adhesive resin composition (the adhesive resin composition itself), a liquid obtained by diluting the adhesive resin composition with a solvent, or a liquid obtained by dispersing the adhesive resin composition in an emulsion in a solvent. Thermosetting adhesives may be a one-component type in which the adhesive resin and curing agent are mixed during the manufacturing process, or a two-component type in which the adhesive resin and curing agent are stored separately and mixed immediately before application.

[0106] The viscosity of the thermosetting adhesive is preferably between 100 and 1500 mPas. If the viscosity is less than 100 mPas, it is difficult to apply the adhesive resin composition to the desired thickness. On the other hand, if the viscosity exceeds 1500 mPas, uniform application and application in a short time become difficult, thickness variations occur in the width and length directions, and productivity further deteriorates.

[0107] The adhesive resin composition constituting the adhesive resin coating is as described above. From the viewpoint of versatility, cost, and performance diversity, the thermosetting adhesive preferably contains epoxy resin. Furthermore, the thermosetting adhesive preferably contains 50% by mass or more of thermosetting resin, and more preferably contains 50% by mass or more of epoxy resin. The curing agent preferably contains one or more selected from the group consisting of amine-based curing agents, amide-based curing agents, and imidazole-based curing agents. For example, a thermosetting adhesive containing one or more selected from the group consisting of amine-based curing agents, amide-based curing agents, and imidazole-based curing agents, and containing 50% by mass or more of epoxy resin is preferred. The ratio of thermosetting resin to curing agent can be appropriately adjusted depending on the type of thermosetting resin and curing agent, but for example, the functional group equivalent of the curing agent can be 0.8 to 1.2 relative to the functional group equivalent of the thermosetting resin.

[0108] The thermosetting adhesive is preferably a dispersion containing at least some of the curing agent, and the particle size of the curing agent crystals dispersed in the thermosetting adhesive is preferably 2 to 20 μm. If the particle size of the curing agent crystals is less than 2 μm, handling becomes difficult, and at the same time, all of the curing agent often dissolves due to heating during the heating, drying, and solidification process. In this case, the unreacted curing agent that did not react with the thermosetting resin due to heating is difficult to recrystallize even if it becomes supercooled during the cooling process following the heating, drying, and solidification step, because there are no nucleation sites for the curing agent crystals. For this reason, it may be difficult to leave a predetermined amount of curing agent in a crystalline state on the adhesive resin composition film. Furthermore, if the particle size is greater than 20 μm, it is difficult to form the adhesive resin composition film on the surface of the steel plate as a thin film of 10 μm or less.

[0109] (Adhesive application method) The specific application method for thermosetting adhesives is not particularly limited and is appropriately selected according to the properties of the thermosetting adhesive. For example, it can be done using methods such as the roll coater method, gravure coater method, air doctor coater method, blade coater method, knife coater method, rod coater method, kiss coater method, bead coater method, cast coater method, rotary screen method, immersion coating method in which the steel plate is coated while immersed in liquid thermosetting adhesive, and slot orifice coater method in which the liquid thermosetting adhesive is dropped onto the steel plate from an orifice to coat it.

[0110] In addition to these methods, the process can also be carried out using curtain coating, spray coating (which uses the principle of atomization to spray liquid thermosetting adhesive in a mist), inkjet, and electrodeposition coating methods.

[0111] [Heating drying solidification process] The heating, drying, and solidification process involves heating a steel plate coated with a thermosetting adhesive, followed by cooling, to form an adhesive resin composition film on the surface of the steel plate. Heating causes a reaction between a portion of the thermosetting resin and a portion of the curing agent in the adhesive applied to the steel plate surface, resulting in the formation of a semi-cured adhesive resin composition. Furthermore, when using a thermosetting adhesive containing a solvent, heating causes a reaction between a portion of the thermosetting resin and a portion of the curing agent, while the solvent in the adhesive evaporates, further forming a semi-cured adhesive resin composition. Additionally, a portion of the curing agent may not dissolve during heating or may recrystallize upon cooling after heating. This results in the formation of an adhesive resin composition film in which a predetermined amount of curing agent is dispersed in a crystalline state.

[0112] (Heating method) For heating (baking), known heating and drying (baking) methods can be used, including hot air drying, induction heating, infrared heating, and vacuum heating.

[0113] As a result of the inventors' studies, it was found that controlling the heating (drying) conditions, specifically the heating temperature (T) and heating time, is extremely important in order to keep the depolarized light scattering intensity I of the adhesive resin composition coating within the above-mentioned range. Specifically, the heating temperature T should be within the temperature range of 100 to 250°C, and the heating time should be controlled to satisfy the following equation (i), depending on the type of thermosetting adhesive used. 0.8 ≤ t / t0 ≤ 18.0 ···(i) However, the meaning of each symbol in equation (i) above is as follows: t: Heating time in the heating, drying, and solidification process t0: The time required to form an adhesive resin composition film with a softening onset temperature (Tss) of 50°C when drying a thermosetting adhesive at temperature T.

[0114] By setting t / t0 to 0.8 or higher, the depolarized light scattering intensity I is increased to 50.00 × 10⁻⁶. 7 The following can be achieved. Furthermore, by setting t / t0 to 18.0 or less, the depolarized light scattering intensity I can be set to 1.00 × 10⁻⁶. 7 The above can be applied. Here, time t0 is determined as follows: First, a thermosetting adhesive is applied to the surface of the steel plate. Then, it is heated at temperature T for various times, and the Tss of the adhesive resin composition film formed on the steel plate is measured by the method described above. From the measurement results, the heating time required to make Tss = 50°C at heating temperature T is determined, and this is defined as t0.

[0115] (Cooling method) After heating a steel plate coated with a thermosetting adhesive, known cooling methods can be used for cooling. Air cooling, water cooling, mist cooling, and laminar flow cooling can all be used in combination, and some can be used intermittently. A cooling rate of 1 to 600°C / min is preferred. If the cooling rate is less than 1°C / min, the curing reaction of the adhesive resin composition proceeds during cooling, making it difficult to leave a predetermined amount of curing agent crystals, or an adhesive resin composition film with a maximum penetration λ of less than 15% may be formed. On the other hand, if the cooling rate exceeds 600°C / min, the cooling rate becomes uneven depending on the area, and thermal stress generated from the difference in linear expansion coefficients between the steel plate and the adhesive resin concentrates in the rapidly cooled areas, which may reduce the magnetic properties of the steel plate.

[0116] <Suitable manufacturing method> Furthermore, the depolarized light scattering intensity I is set to 1.20 × 10⁻⁶ 7 ~18.00 x 10 7 Therefore, in order to ensure resistance to adhesive blocking and achieve short curing time, the Tg of the adhesive resin uc It is preferable to set the temperature to 30°C or higher, set the heating temperature in the heating, drying, and solidification process to a temperature T within the range of 100 to 190°C, and control the heating time to satisfy the following equation (ii) according to the type of thermosetting adhesive used. 1.3 ≤ t / t0 ≤ 15.0 ···(ii) However, the meaning of each symbol in equation (ii) above is as follows: t: Heating time in the heating, drying, and solidification process t0: The time required to form an adhesive resin composition film with a softening onset temperature (Tss) of 50°C when drying a thermosetting adhesive at temperature T.

[0117] If the softening start temperature Tss is to be 70°C or higher, it is preferable that t / t0 be 2.0 or higher, and if the softening start temperature Tss is to be 70°C or higher, it is preferable that t / t0 be 8.0 or lower. Furthermore, if the maximum penetration depth λ is to be 20% or higher, it is preferable that t / t0 be 8.0 or lower.

[0118] <How to use> (Storage method for electrical steel sheet coated with adhesive resin composition) The adhesive resin composition-coated electrical steel sheet of the present invention can be stored at room temperature and humidity without strict temperature and humidity control because the curing agent remains in an appropriate amount in a crystalline state within the adhesive resin composition coating. Furthermore, even when transported by ship, adhesive blocking and bonding blockage can be prevented, and a decrease in adhesive performance can be suppressed. Therefore, it can be stored using known steel sheet storage methods. Specifically, the adhesive resin composition-coated electrical steel sheet can be wound into a coil, cut into sheets and laminated, and then packaged in paper or resin, or stored at room temperature and humidity without packaging. For longer-term storage, it can also be stored at low temperatures in a refrigerator or freezer.

[0119] <Manufacturing of iron cores> The adhesive resin composition-coated electrical steel sheet of the present invention can be used in the manufacture of an iron core. For example, the adhesive resin composition-coated electrical steel sheet of the present invention can be punched and sheared, laminated, and then the laminated bodies can be heat-pressed to manufacture an iron core. The iron core may also be called an adhesive core or motor core.

[0120] (Punching and shearing method) It is possible to process and laminate the materials using known punching and shearing methods. Specifically, the adhesive resin-coated electrical steel sheet is continuously fed into a die from a coiled adhesive resin-coated electrical steel sheet. At this time, processing oil is sprayed onto the adhesive resin-coated electrical steel sheet just before it is loaded into the die. Then, the adhesive resin-coated electrical steel sheet is punched out multiple times sequentially into the desired shape while being fed into the die, and shearing is performed once all the desired shapes have been processed. Finally, the sheared adhesive resin-coated electrical steel sheet is dropped into a receiver in the die and laminated.

[0121] (Heat-press method) It is possible to press and bond an iron core made of laminated adhesive resin composition-coated electromagnetic steel sheets within a mold, or to remove the iron core made of laminated adhesive resin composition-coated electromagnetic steel sheets from the mold and place it in a heating device for pressurization. Known heating methods can be applied. Specifically, methods such as hot air heating using the heat flow of hot air from an oven, electrical resistance heating using resistance heating, low-frequency / high-frequency induction heating using induction power, and infrared light heating such as near-infrared and far-infrared using radiant heat can be employed. Among these, heating with a near-infrared heater is preferred. Heating with a near-infrared heater has a fast heater response speed and can heat with high energy density, allowing the iron core to be heated at high speed. As a result, it becomes relatively easy to raise the temperature of the iron core to the curing temperature without significantly advancing the curing of the semi-cured adhesive resin composition that constitutes the adhesive resin composition coating.

[0122] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless its essence is changed. [Examples]

[0123] <Test material> [Steel plate] A non-oriented electrical steel sheet with a thickness of 0.35 mm was used. [Thermosetting adhesive] Table 1 shows the raw materials used in the thermosetting adhesive. Table 2 shows the composition of the adhesive resin. The values ​​in Table 2 represent the amount (parts by mass) of each raw material relative to 100 parts by mass of the total epoxy resin.

[0124] [Table 1]

[0125] [Table 2]

[0126] <Formulation of adhesive resin compositions, manufacture of thermosetting adhesives> A resin raw material, additives, curing agent, and curing accelerator were prepared using the compositions shown in Table 2 to obtain an adhesive resin composition. Then, a solvent was added to the adhesive resin composition so that the solid content concentration in the liquid was 40% by mass, and the mixture was stirred and mixed at room temperature for 3 hours to obtain a thermosetting adhesive. The numbers of the thermosetting adhesives shown in Tables 3 to 5 correspond to the numbers of the adhesive resin compositions shown in Table 2.

[0127] <Tg uc Measurement > After casting the thermosetting adhesive onto a glass plate, it was placed in a desiccator and dried under atmospheric pressure for 24 hours. Subsequently, it was vacuum-dried at room temperature for 48 hours to remove the solvent. Following vacuum drying, the cast film was recovered from the glass plate and heated at 5°C / min using a differential scanning calorimeter (DSC) (Hitachi High-Tech Science Corporation). The glass transition temperature Tg (midpoint glass transition temperature) in the uncured state was measured in accordance with JIS K 7121:2012. The results are shown in Table 2.

[0128] <Example 1> <Manufacture of electrical steel sheet coated with adhesive resin composition> After cleaning the surface of a 220 x 200 mm non-oriented electrical steel sheet with acetone, thermosetting adhesive 1 was applied to the surface (200 x 200 mm) of the non-oriented electrical steel sheet using a roll coater (manufactured by Furnace Co., Ltd.) to a film thickness of 4.5 μm after drying. After application, it was dried at 140°C for 2.5 minutes to remove the solvent, forming an adhesive resin composition film. Furthermore, after drying, cooling water was sprayed onto the steel sheet surface and cooled to room temperature to obtain an electrical steel sheet coated with the adhesive resin composition. The steel sheet temperature was measured by attaching a thermocouple to the adhesive margin on the surface of the steel sheet.

[0129] <Examples 2-14> An adhesive resin composition-coated electromagnetic steel sheet was obtained in the same manner as in Example 1, except that the thermosetting adhesive and drying conditions shown in Tables 3 to 5 were used.

[0130] <Confirmation of the hardening agent in its crystalline state> Immediately after drying, the electrical steel sheets coated with the adhesive resin composition were observed using a polarizing microscope in the manner described above to determine whether a portion of the curing agent was present in the adhesive resin composition coating in a crystalline state. As a result, with the exception of Comparative Example 2 described later, it was confirmed that a portion of the curing agent was present in the adhesive resin composition coating in a crystalline state.

[0131] <Measurement of light scattering intensity> Immediately after drying, the electrical steel sheet coated with the adhesive resin composition was immersed in hydrochloric acid to dissolve the steel sheet portion and remove the adhesive resin composition coating.

[0132] Furthermore, for comparative study, cast films were also prepared. On the surface of a 220 x 200 mm biaxially oriented PET film (75 μm thick, manufactured by Unitika Ltd.), the thermosetting adhesive of each example was applied (4.5 μm thick) to a 200 x 200 mm area using a roll coater (manufactured by Furnace Co., Ltd.). After application, the films were dried under the same conditions as the adhesive resin composition-coated electrical steel sheets of each example, and the solvent was removed to form an adhesive resin composition film. After drying, the PET film was immersed in cooling water and cooled to room temperature, and then the adhesive resin composition film was peeled off the PET film.

[0133] The depolarized light scattering intensity (I0 and I1, respectively, the integral value of scattered light at scattering angles from 0° to 22°) of adhesive resin composition coatings sampled from Matsunami Glass Industry Co., Ltd.'s Cover Glass No. 1, as well as from adhesive resin composition-coated electromagnetic steel sheets and cast films, was measured using a light scattering analyzer (PP-1000, manufactured by Otsuka Electronics Co., Ltd., with the distance (L) between the sample and the 2D detector set to 20 cm). From these measurements, I = I1 / I0 was calculated and defined as the depolarized light scattering intensity I of the adhesive resin composition coating. Note that I0 and I1 were both the average values ​​of three samples.

[0134] Tables 3-5 show the depolarized light scattering intensity I of the calculated adhesive resin composition coatings. In the tables, the measured values ​​for adhesive resin composition coatings taken from adhesive resin composition coated electrical steel sheets are shown in the "Steel Sheet" column, and the measured values ​​for adhesive resin composition coatings taken from cast films are shown in the "PET" column.

[0135] <Measurement of Tss, λ, and t0> Specimens were cut out from the electromagnetic steel sheet coated with the adhesive resin composition immediately after drying and embedded in an epoxy resin. After the epoxy resin hardened, it was polished to obtain a smooth cross-section of the steel sheet. The cross-section of the steel sheet was observed under a microscope to measure the thickness of the adhesive resin composition film. Further, a 7×7 mm specimen was cut out, placed in a sample tube for the needle penetration mode of a thermomechanical analyzer (TMA, manufactured by Hitachi High-Tech Science Corporation) with the adhesive-coated surface facing up, and heated in the needle penetration mode from -50°C to 300°C at 5°C / min. Then, the penetration length of the TMA probe needle into the adhesive resin composition film coated on the steel sheet surface was measured. Based on this data, Tss was determined. Also, based on this data, the maximum value of the needle penetration length was obtained, and λ was calculated. The results are shown in Tables 3 to 5.

[0136] Furthermore, electromagnetic steel sheets coated with a thermosetting adhesive on the surface so that the film thickness after drying was 4.5 μm were prepared as samples with the drying time varied at 140°C. The needle penetration length into the adhesive resin composition film was measured in the TMA needle penetration mode under the same conditions, and the correlation between the drying time and Tss when dried at the temperatures shown in Tables 3 to 5 was determined. Then, from this data, the time t0 when Tss of the adhesive resin composition film reached 50°C was determined. The results are shown in Tables 3 to 5.

[0137] <Adhesive blocking test> Two 50×50 mm electromagnetic steel sheets coated with the adhesive resin composition immediately after drying were cut out and laminated so that the adhesive surfaces overlapped by 40×50 mm. The laminated steel sheets were pressed at 8 MPa for 30 minutes at 50°C. After unloading, a precision spring scale was used to measure the tensile shear adhesive strength between the adhesive surfaces and evaluated according to the following evaluation criteria. The greater the adhesive blocking between the resin layers of the adhesive composition, the greater the tensile shear adhesive strength. Therefore, the adhesive blocking resistance was evaluated with the following scores (in the order of A>B>C>D, with a preventive effect). The measurement was performed 5 times each. A: 0.1 kPa or less, B: more than 0.1 kPa and 0.5 kPa or less, C: more than 0.5 kPa and 1 kPa or less, D: more than 1 kPa

[0138] <Adhesive blocking test> Two 50 x 50 mm sheets of electrical steel coated with an adhesive resin composition were cut immediately after drying and laminated so that the adhesive surfaces overlapped by 40 x 50 mm. The laminated steel sheets were placed in an oven (relative humidity 90%) set to a temperature of 50°C while being pressurized at 8 MPa for 12 weeks. After 12 weeks, the laminated steel sheets were removed from the oven and unloaded. After unloading, the tensile shear adhesive strength between the adhesive surfaces was measured using a precision spring scale. If adhesive blocking progresses between the adhesive resin layers during storage, the tensile shear adhesive strength will increase. Therefore, the resistance to adhesive blocking was evaluated using the following scoring system (A > B > C > D in order of effectiveness). Each measurement was performed 5 times. A: 0.1kPa or less, B: More than 0.1kPa and less than 0.5kPa, C: More than 0.5kPa and less than 1kPa, D: More than 1kPa

[0139] <Short curing time in the thermocompression bonding process> Two 100 x 25 mm sheets of adhesive resin-coated electrical steel were cut immediately after drying, and laminated so that the adhesive surfaces overlapped by 25 x 25 mm. The laminated steel sheets were heated to 200°C at a rate of 5°C / second while being pressurized at 1 MPa, and held at 200°C for 1 minute. After cooling to room temperature, the tensile shear adhesive strength before storage was measured in accordance with JIS K 6850:1999 (adhesive strength immediately after drying). Furthermore, the same tensile shear adhesive strength test was performed using electrical steel sheets coated with adhesive resin that had been stored in an oven at 50°C for 12 weeks (relative humidity 90%), and the tensile shear adhesive strength after storage was measured (adhesive strength after storage). Each measurement was performed five times. A: 10 MPa or more, B: 5 MPa or more but less than 10 MPa, C: 1 MPa or more but less than 5 MPa, D: less than 1 MPa

[0140] [Table 3]

[0141] [Table 4]

[0142] [Table 5]

[0143] <Comparative Examples 1-3> An adhesive resin composition-coated electrical steel sheet was obtained in the same manner as in Example 1, except that the thermosetting adhesive and drying conditions shown in Table 6 were used.

[0144] Using the obtained adhesive resin composition-coated electrical steel sheets, Tss, λ, and light scattering intensity were measured in the same manner as in Examples 1 to 14. Furthermore, adhesive blocking tests, bonding blocking tests, and the feasibility of short-time curing in the thermocompression bonding process were evaluated.

[0145] [Table 6]

[0146] <Comparative Example 4> A high molecular weight epoxy prepolymer (Mn=6000) was prepared using bisphenol A type epoxy (Epicote 828, manufactured by Mitsubishi Chemical Corporation) in accordance with Example 43 of Japanese Patent Publication No. 11-162724. Next, an acrylic resin (mass ratio: 174 / 87 / 29) consisting of methacrylic acid, styrene, and ethyl acrylate was polymerized. 267 parts of the high molecular weight epoxy prepolymer and 200 parts of the acrylic resin were dissolved in a solvent, and then an amine-based catalyst (diethylaminoethanol) was added and the mixture was stirred at 105°C for 3 hours. Deionized water was then added over 30 minutes to obtain an emulsion with a solid content of 25%. To this emulsion, 5 parts of phenol resin (bisphenol A resol type phenol resin) and 20 parts of DICY were added per 100 parts of the resin in the emulsion to obtain an epoxy emulsion adhesive (thermosetting adhesive 6). Then, the thermosetting adhesive 6 was applied to the surface of the electrical steel sheet using a bar coater, dried at 200°C for 10 minutes within the sheet temperature range described in paragraph 0057 of the published patent application, and cooled to obtain an electrical steel sheet coated with the adhesive resin composition.

[0147] Using the obtained adhesive resin composition-coated electromagnetic steel sheets, Tss, λ, and light scattering intensity were measured in the same manner as in Examples 1 to 14. Furthermore, adhesive blocking tests and the feasibility of short-time curing in the thermocompression bonding process were evaluated. As a result, the light scattering intensity was approximately <1 × 10⁻⁶. 6 As with Comparative Examples 2 and 3, the resistance to adhesive blocking and the adhesive strength after storage were both rated D.

[0148] <Result> Examples 1 to 14 show that an electrical steel sheet coated with an adhesive resin composition film consisting of a semi-cured product of the adhesive resin composition, with the amount of curing agent crystals controlled to a predetermined amount, suppresses adhesive blocking and bonding blocking even when stored for a long period in a high-temperature, humid environment, and can harden quickly in the thermocompression bonding process to exhibit adhesive strength.

[0149] On the other hand, Comparative Example 1 shows that if the light scattering intensity falls below the upper limit, sufficient adhesive strength cannot be obtained even if heat-pressed immediately after drying. This is presumed to be due to curing agent crystals remaining in the adhesive resin composition coating even after heat-pressing. Comparative Examples 2-4 show that if the light scattering intensity falls below the lower limit, adhesive blocking occurs during storage, and the adhesive strength after storage also decreases. This is presumed to be due to the curing agent, which dissolved during drying, undergoing a slow curing reaction during storage. Furthermore, Comparative Example 4 shows that even when manufactured using known adhesives and known methods, it is not easy to manufacture the adhesive resin composition coated electromagnetic steel sheet of the present invention. Moreover, since it is outside the scope of the components of the present invention, adhesive blocking occurs during storage, similar to Comparative Examples 2 and 3, and the adhesive strength after storage also decreases.

[0150] From a comparison of Examples 1, 2, and 8 with other examples, the light scattering intensity was 18.60 × 10⁻¹⁴. 7 In the above cases, the adhesive strength immediately after drying is slightly low. Furthermore, in Examples 1, 2, and 8, the adhesive strength after storage is also slightly low. This is presumed to be because some curing agent crystals remain in the adhesive resin composition film even after heat bonding, and these crystals act as a starting point for a decrease in strength, resulting in a decrease in adhesive strength.

[0151] Furthermore, a comparison of Examples 5, 10, 11, and 14 with other examples showed that the light scattering intensity was 1.00 × 10⁻⁶. 7 ~1.10×107 However, the adhesive blocking resistance tends to deteriorate slightly. This is presumed to be due to a slow curing reaction occurring between the adhesive resin composition coatings during storage, caused by the curing agent dissolved during the heat drying and solidification process.

[0152] Furthermore, comparing Examples 5 and 6, although the Tss is the same, the adhesive blocking resistance is better in Example 6 than in Example 5. This is presumed to be due to the following: In Example 5, the Tg of the adhesive resin composition 2 used was uc While the temperature of the adhesive resin composition 1 used in Example 6 was less than 30°C, in Example 6, the Tg of the adhesive resin composition 1 used was uc The temperature is above 30°C. As a result, more heat input was applied in Example 5 to bring Tss to 80°C during the heating, drying, and solidification process. Consequently, it is presumed that more curing agent dissolved in Example 5 during the heating, drying, and solidification process. In fact, the area ratio of curing agent crystals is also smaller in Example 5. Therefore, it is presumed that in Example 5, where more curing agent dissolved, the slow curing reaction proceeded more easily during storage, resulting in slightly inferior adhesive blocking resistance.

[0153] Furthermore, a comparison of Example 1 with Examples 2-4, 6, 7, 9, and 14 shows that the adhesive resin composition-coated electrical steel sheet dried at 140°C for less than 1.1 × t0 hours exhibits poor resistance to adhesive blocking. This is presumed to be due to the adhesive resin composition not being sufficiently cured after drying. Moreover, a comparison of Example 14 with Examples 2-4, 6, 7, and 9 shows that the adhesive resin composition-coated electrical steel sheet dried at 140°C for 15.0 × t0 hours exhibits superior resistance to adhesive blocking. This is presumed to be due to the dissolution of the curing agent crystals during the heat drying and solidification process, and the subsequent slow curing reaction caused by the dissolved curing agent during storage, when dried for more than 15.0 × t0 hours. [Industrial applicability]

[0154] According to the present invention, an adhesive resin composition coated electrical steel sheet can be obtained that prevents adhesive blocking and deterioration of adhesive performance even when stored for a long period of time after adhesive application and drying, and that allows the adhesive resin composition coating to harden in a short time during heat-press bonding. Therefore, the adhesive resin coated electrical steel sheet of the present invention can be suitably used as a material for iron cores (stators, rotors, etc.) of motors in home appliances (air conditioners, vacuum cleaners, audio equipment, etc.) and automobiles (HV, EV).

Claims

1. An adhesive resin composition coated electrical steel sheet having a steel sheet and an adhesive resin composition coating on at least one surface of the steel sheet, The aforementioned adhesive resin composition coating is a semi-cured product of an adhesive resin composition comprising an adhesive resin and a curing agent, at least in part, which include a thermosetting resin. The maximum penetration λ of the adhesive resin composition coating at 100 to 300°C, as measured by thermomechanical analysis as described in JIS K 7196:2012, is 3% or more and less than 100%. A portion of the curing agent is present in the adhesive resin composition film in a crystalline state. The depolarized light scattering intensity I of the adhesive resin composition coating is 1.00 × 10 ７ ~50.00 x 10 ７ That is, Adhesive resin composition coated electrical steel sheet.

2. The depolarized light scattering intensity I of the adhesive resin composition coating is 1.20 × 10 ７ ~18.00 x 10 ７ That is, An electrical steel sheet coated with the adhesive resin composition according to claim 1.

3. The softening onset temperature Tss of the adhesive resin composition coating, as measured by thermomechanical analysis as described in JIS K 7196:2012, is 50°C or higher, and the maximum penetration λ at 100-300°C is 15% or higher. An electrical steel sheet coated with the adhesive resin composition according to claim 1.

4. The thermosetting resin comprises one or more selected from epoxy resins, acrylic resins, urethane resins, and unsaturated polyester resins. An electrical steel sheet coated with the adhesive resin composition according to claim 1.

5. The curing agent comprises one or more selected from amine-based curing agents, amide-based curing agents, and imidazole-based curing agents. An electrical steel sheet coated with an adhesive resin composition according to any one of claims 1 to 4.

6. A method for manufacturing an electrical steel sheet coated with an adhesive resin composition according to any one of claims 1 to 4, A coating step of applying a liquid thermosetting adhesive containing the adhesive resin and the curing agent to at least one surface of the steel plate, The process includes a heating, drying, and solidification step in which the steel plate to which the thermosetting adhesive has been applied is heated, then cooled to form an adhesive resin composition film on the surface of the steel plate. The heating temperature in the aforementioned heating, drying, and solidification step is a temperature T within the range of 100 to 250°C. The heating time in the aforementioned heating, drying, and solidification step satisfies the following equation (i): A method for manufacturing an electrical steel sheet coated with an adhesive resin composition. 0.8≦t / t ０ ≦18.0 ・・・(i) However, the meaning of each symbol in equation (i) above is as follows: t: Heating time in the heating, drying, and solidification step. t ０ : The time required to form an adhesive resin composition film with a softening start temperature of 50°C when the thermosetting adhesive is dried at the aforementioned temperature T.

7. Glass transition temperature Tg of the adhesive resin ｕｃ The temperature is 30°C or higher. The heating temperature in the aforementioned heating, drying, and solidification step is a temperature T within the range of 100 to 180°C. The heating time in the aforementioned heating, drying, and solidification step satisfies the following equation (ii): A method for manufacturing an electrical steel sheet coated with an adhesive resin composition according to claim 6. .3≦t4 ０ ≦.... ・・・(ii) However, the meaning of each symbol in equation (ii) above is as follows: t: Heating time in the heating, drying, and solidification step. t ０ : Time required to form a coating of the adhesive resin composition having a softening start temperature of 50 °C when drying the thermosetting adhesive at the temperature T

8. The adhesive resin contains 50% by mass or more of a thermosetting resin, which is one or more selected from epoxy resin, acrylic resin, urethane resin, and unsaturated polyester resin, relative to the total amount of the adhesive resin. A method for manufacturing an electrical steel sheet coated with an adhesive resin composition according to claim 6.

9. The curing agent comprises one or more selected from amine-based curing agents, amide-based curing agents, and imidazole-based curing agents. A method for manufacturing an electrical steel sheet coated with an adhesive resin composition according to claim 6.

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