Adhesive resin composition-coated electromagnetic steel sheet and method for manufacturing same

Abstract

An adhesive resin composition-coated electromagnetic steel sheet comprising a steel sheet and an adhesive resin composition coating film provided to at least one surface of the steel sheet, wherein the adhesive resin composition coating film is a semi-cured object of an adhesive resin composition that contains a curing agent and an adhesive resin containing a thermosetting resin as at least a portion thereof, the maximum penetration λ of the adhesive resin composition coating film at 100-300°C as measured through a thermomechanical analysis described in JIS K 7196:2012 is not less than 3% but less than 100%, a portion of the curing agent exists in the adhesive resin composition coating film in a crystal state, and the depolarization light scattering intensity I of the adhesive resin composition coating film is 1.00×107 to 50.00×107.

Description

Adhesive resin composition coated electrical steel sheet and method for producing same

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

[0002] Iron cores used in motors and the like are assembled by punching out electromagnetic steel sheets into a predetermined shape, shearing them, and then laminating and bonding them together. A known bonding method is to use a thermosetting adhesive, which can bond the sheets together without causing processing distortion or thermal distortion, provides insulation between the laminated steel sheets, increases eddy current resistance, reduces iron loss, and also has excellent heat resistance under actual usage conditions.

[0003] The most common method for laminating and bonding magnetic steel sheets with a thermosetting adhesive is to laminate and thermocompress the magnetic steel sheets after punching and shearing them.Methods for applying a thermosetting adhesive to the magnetic steel sheet surface can be broadly divided into two types depending on the timing of application of the thermosetting adhesive.

[0004] One method is to apply a thermosetting adhesive to the magnetic steel sheets after punching. This method can be further divided into two methods: one in which the thermosetting adhesive is sprayed onto the surface of the magnetic steel sheets using a spray or the like just before shearing, and then the sheets are sheared and stacked; and one in which the laminated core is immersed in adhesive liquid after punching, shearing, and stacking are completed, and the adhesive is allowed to penetrate between the laminated magnetic steel sheets.

[0005] The other method is to apply a thermosetting adhesive to at least one surface of an electrical steel sheet in advance, dry the sheet, and then punch and shear the sheet, followed by lamination. Hereinafter, an electrical steel sheet having an adhesive resin composition coating, in which a thermosetting adhesive is applied to at least one surface of the electrical steel sheet and then dried, may be referred to as an "adhesive resin composition-coated electrical steel sheet."

[0006] Among these methods for laminating and fixing magnetic steel sheets, the latter has attracted attention in recent years because it is superior in terms of handling of adhesive application, uniformity, productivity, and the like.

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

[0008] Iron cores are manufactured by punching, shearing, laminating, and thermocompression bonding adhesive resin composition-coated electrical steel sheets. Therefore, not only is there a need for a technology for uniformly coating the adhesive resin composition film on the steel sheet surface, but there is also a need for a technology for preventing defects such as poor peeling between the steel sheets when the steel sheets are wound up and unwound into a coil and insufficient adhesive strength after thermocompression bonding.

[0009] It should be noted that, in general, the processes from the application of a thermosetting adhesive when manufacturing an adhesive resin composition-coated electrical steel sheet to the thermocompression bonding when manufacturing an iron core are not continuous. Therefore, the manufacturing process for adhesive resin composition-coated electrical steel sheets (semi-finished products) includes storage and transportation steps from the completion of drying until the start of punching. Furthermore, the storage period can be extremely long, lasting several months or more. Furthermore, steel sheets may be stored for several weeks in a ship's hold, which may be exposed to a high-temperature, humid environment of approximately 50°C during transportation. During this storage period, the adhesive resin composition coating of the adhesive resin composition-coated electrical steel sheet is in a semi-cured state (non-equilibrium state) in which the irreversible curing reaction has been stopped midway.

[0010] Therefore, adhesive resin composition-coated electrical steel sheets are very unstable. Therefore, if the adhesive is applied and dried and then stored for a long period of time in a high-temperature, humid environment, defects such as those described below (A) and (B) are likely to occur. Note that a high-temperature, humid environment refers, for example, to the environment inside a warehouse on a ship sailing near the equator, where the storage temperature is approximately 50°C. (A) Adhesive blocking: The adhesive resin undergoes a curing reaction between the surfaces of the adhesive resin composition coating during storage, resulting in adhesive bonding between the stacked and stored steel sheets. (B) Deterioration of adhesive ability: The adhesive resin composition coating undergoes excessive curing during storage. As a result, the adhesive resin does not soften sufficiently even when heated for thermocompression bonding, and is unable to penetrate the irregularities on the adherend surface, resulting in the anchoring effect not being exhibited and the adhesive ability between the laminated steel sheets being reduced.

[0011] Therefore, a technique has been disclosed that solves this instability by controlling the curing state of the adhesive resin. Patent Document 1 discloses a technique in which an adhesive resin having a Tg (glass transition temperature) or softening temperature of 60°C or higher is used to coat an electromagnetic steel sheet. By vitrifying the adhesive resin at around room temperature, it is possible to prevent stickiness of the adhesive layer surface and adhesive blocking. This technique is effective when an adhesive resin composition-coated electromagnetic steel sheet is punched and thermocompressed immediately after drying to manufacture an iron core.

[0012] Furthermore, Patent Documents 2 to 4 disclose techniques for suppressing the curing reaction at room temperature by using a latent curing agent as a curing agent for a thermosetting resin. Here, a latent curing agent is a curing agent to which latency has been imparted, as explained, for example, in Non-Patent Document 1. The latency of the curing agent makes it possible to suppress the reaction at room temperature, and by applying an external stimulus trigger such as heat, light, moisture, or pressure, the curing reaction of the thermosetting resin can be rapidly promoted.

[0013] Furthermore, Patent Documents 5 and 6 suggest that blocking during storage can be prevented by coating the magnetic steel sheet with an adhesive resin that hardens with a latent hardener.

[0014] JP 2002-260910 A JP 2020-100727 A JP 2017-031268 A JP 2014-152236 A JP 6-182296 A JP 11-162724 A

[0015] Journal of the Adhesion Society of Japan, vol. 53, No. 4 (2017), pp. 122-128

[0016] However, Patent Document 1 does not disclose a method for suppressing the curing reaction during storage of an adhesive resin composition-coated electrical steel sheet. The method of Patent Document 1 may cause adhesion-induced blocking in the general production of adhesive resin composition-coated steel sheets that involve long-term storage, and may also result in a decrease in adhesive ability during thermocompression bonding.

[0017] Patent Documents 2 to 4 disclose techniques for minimizing the reaction between the resin and the curing agent in the adhesive liquid before application to the steel sheet, and for maintaining a viscosity that facilitates application even during storage of the adhesive (storage stabilization of the adhesive liquid and prolongation of the pot life), but do not disclose anything about the stability of the adhesive resin in an adhesive resin composition-coated electrical steel sheet that has been subjected to a heating step by drying.

[0018] Patent Documents 5 and 6 do not disclose the state of the latent curing agent in the adhesive resin after heat drying. Once heated in the drying process, the curing agent often changes state and loses its latency. Therefore, unless the state of the latent curing agent in the adhesive resin composition film after drying is controlled, it is difficult to suppress the progress of the curing reaction during storage, which may result in adhesion-related 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 occurs on the order of several months at room temperature, often corresponds to a matter of minutes at the curing temperature. Therefore, if the rate at which the curing agent in the adhesive resin composition coating of the adhesive resin composition coated electrical steel sheet diffuses into the adhesive resin or the rate at which the curing agent reacts with the adhesive resin is reduced, the curing rate in the thermocompression bonding step when the sheet is used to manufacture an iron core also decreases, which can result in reduced productivity of the iron core.

[0020] As mentioned above, the manufacturing process from the application of a thermosetting adhesive when manufacturing an adhesive resin composition-coated electrical steel sheet (semi-finished product) to the thermocompression bonding when manufacturing an iron core (finished product) is generally not continuous. Therefore, during the period from obtaining the adhesive resin composition-coated electrical steel sheet (from the completion of drying of the adhesive) 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 strength during storage (especially during long-term storage) has been an issue. In addition, the thermocompression bonding process when manufacturing an iron core using an adhesive resin composition-coated electrical steel sheet must be able to cure in a short time, enabling efficient production of iron cores.

[0021] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an adhesive resin composition-coated electrical steel sheet that can prevent adhesive blocking and a decrease in adhesive ability even when stored for a long period of time after the adhesive has been applied and dried, and that allows the adhesive resin composition coating to harden in a short time during the thermocompression bonding step when manufacturing an iron core.

[0022] The present invention has been made to solve the above-mentioned problems, and is summarized as follows: an adhesive resin composition coated electrical steel sheet and a method for producing 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, 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, wherein the adhesive resin composition coating has a maximum penetration λ of 3% or more and less than 100% at 100 to 300°C as measured by thermomechanical analysis according to JIS K 7196:2012, wherein a portion of the curing agent is present in a crystalline state in the adhesive resin composition coating, and wherein the depolarized light scattering intensity I of the adhesive resin composition coating is 1.00 x 10 ７ ~50.00 x 10 ７ An adhesive resin composition coated electrical steel sheet.

[0024] (2) The depolarized light scattering intensity I of the adhesive resin composition film is 1.20 × 10 ７ ~18.00 x 10 ７The adhesive resin composition coated electrical steel sheet according to (1) above,

[0025] (3) The adhesive resin composition coated electrical steel sheet according to (1) or (2) above, wherein the adhesive resin composition coating has a softening start temperature Tss of 50°C or higher and a maximum penetration λ of 15% or higher at 100 to 300°C, as measured by thermomechanical analysis according to JIS K 7196:2012.

[0026] (4) The adhesive resin composition-coated electrical steel sheet according to any one of (1) to (3) above, wherein the thermosetting resin comprises at least one resin selected from the group consisting of epoxy resin, acrylic resin, urethane resin, and unsaturated polyester resin.

[0027] (5) The adhesive resin composition-coated electrical steel sheet according to any one of (1) to (4) above, wherein the curing agent comprises at least one selected from the group consisting of an amine-based curing agent, an amide-based curing agent, and an imidazole-based curing agent.

[0028] (6) A method for producing an adhesive resin composition-coated electrical steel sheet according to any one of (1) to (4) above, comprising: an application step of applying a liquid thermosetting adhesive containing the adhesive resin and the curing agent to at least one surface of the steel sheet; and a heat-dry-solidification step of heating the steel sheet coated with the thermosetting adhesive and then cooling it to form an adhesive resin composition coating on the surface of the steel sheet, wherein the heating temperature in the heat-dry-solidification step is a temperature T within a temperature range of 100 to 250°C, and the heating time in the heat-dry-solidification step satisfies the following formula (i): 0.8≦t / t ０ ≦18.0 (i) where the meanings of the symbols in the formula (i) are as follows: t: heating time in the heating, drying and solidifying step t ０ : the time required to form an adhesive resin composition coating having a softening starting temperature of 50°C when the thermosetting adhesive is dried at the temperature T

[0029] (7) The glass transition temperature Tg of the adhesive resin ｕｃThe method for producing an adhesive resin composition-coated electrical steel sheet according to (6) above, wherein the temperature T in the heating, drying and solidifying step is 30°C or higher, the heating temperature in the heating, drying and solidifying step is a temperature T in the range of 100 to 190°C, and the heating time in the heating, drying and solidifying step satisfies the following formula (ii): 1.3≦t / t ０ ≦15.0 (ii) where the meanings of the symbols in the formula (ii) are as follows: t: heating time in the heating, drying and solidifying step; ０ : the time required to form an adhesive resin composition coating having a softening starting temperature of 50°C when the thermosetting adhesive is dried at the temperature T

[0030] (8) The method for producing an adhesive resin composition-coated electrical steel sheet according to (6) or (7) above, wherein the adhesive resin contains 50 mass% or more of a thermosetting resin selected from the group consisting of epoxy resin, acrylic resin, urethane resin, and unsaturated polyester resin, based on the total amount of the adhesive resin.

[0031] (9) The method for producing an adhesive resin composition-coated electrical steel sheet according to any one of (6) to (8) above, wherein the curing agent comprises at least one selected from an amine-based curing agent, an amide-based curing agent, and an imidazole-based curing agent.

[0032] According to the present invention, an adhesive resin composition-coated electrical steel sheet can be obtained that can prevent adhesive blocking and deterioration of adhesive ability even when stored for a long period of time after the adhesive has been applied and dried, and that can cure the adhesive resin composition coating in a short time during thermocompression bonding.

[0033] 1 is a diagram for explaining a method for measuring the depolarized light scattering intensity I of an adhesive resin composition film. FIG. 2 is a diagram for explaining a method for analyzing the softening start temperature Tss and the maximum penetration λ of an adhesive resin composition film.

[0034] The present invention will be described in detail below, in the order of the viewpoint, specific embodiments based on the viewpoint, and usage. However, the explanation of the constituent elements described below is an example (typical example) of the embodiment of the present invention, and the present invention is not limited to the following content unless the gist of the present invention is changed.

[0035] <Points of View of the Present Invention> (Control Guidelines) In order to solve the above-mentioned problems, the present inventors conducted the following studies.

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

[0037] Therefore, the present inventors have focused on the following points and carried out investigations to prevent adhesion blocking and a decrease in adhesive ability during storage.

[0038] 1) Elementary process of the slow curing reaction First, the slow curing reaction in the adhesive resin composition coating during storage of adhesive resin composition-coated electrical steel sheets can be broken down into the following three elementary processes: (a) Dissolution of the curing 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 the adhesive resin composition-coated electrical steel sheet, it is necessary to reduce either the dissolution rate, diffusion rate, or reaction activity of the curing agent.

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

[0041] First, the disadvantages of suppressing the slow curing reaction by focusing on (b) and (c) are as follows. To suppress the slow curing reaction within the adhesive resin composition coating by suppressing the diffusion of the curing agent into the adhesive resin (b) and the collision and reaction of the curing agent with the adhesive resin molecules (c), respectively, requires suppressing the thermal mobility of the adhesive resin phase molecules and increasing the activation energy of the curing reaction at room temperature. However, the former requires increasing 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, the latter often also slows the curing reaction rate of the adhesive resin composition coating during thermocompression bonding, impairing iron core productivity.

[0042] On the other hand, focusing on (a), the benefits of leaving a certain amount of curing agent in a crystalline state are as follows: The dissolution of the curing agent in (a) can be controlled by changing the state of the curing agent, and the changes in state between crystallization and dissolution of the curing agent are thermodynamically reversible. Therefore, even if the crystals dissolve due to heating, they can be precipitated by appropriately heating and cooling during heating, drying, and solidification. Furthermore, the crystallized curing agent can remain stable in the adhesive resin composition coating at room temperature without dissolving. Therefore, if a certain amount of curing agent remains in a crystalline state in the adhesive resin composition coating 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 reactivity of the adhesive resin phase molecules, even if these are controlled as described above for short-time curing during the thermocompression bonding process, the slow curing reaction can be stably suppressed during storage.

[0043] Next, a specific embodiment 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 a steel sheet and 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 containing at least a part of a thermosetting resin and a curing agent, and wherein the adhesive resin composition coating has a maximum penetration λ of 3% or more and less than 100% at 100 to 300°C as measured by thermomechanical analysis according to JIS K 7196:2012, a part of the curing agent is present in a crystalline state in the adhesive resin composition coating, and the adhesive resin composition coating has a depolarized light scattering intensity I of 1.00 × 10 ７ ~50.00 x 10 ７ The present invention relates to an adhesive resin composition-coated electrical steel sheet (hereinafter, may be referred to as "the adhesive resin composition-coated electrical steel sheet of the present invention").

[0045] By adopting such a configuration, the following effects can be obtained during storage of the adhesive resin composition-coated electrical steel sheet of the present invention and during each step of thermocompression bonding.

[0046] The following effects are achieved during storage: Prevention of adhesive performance degradation and adhesive blocking: Because 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, dissolution of the curing agent in the adhesive resin can be suppressed during storage of the adhesive resin composition-coated electrical steel sheet. As a result, diffusion and migration 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 interface between adhesive resin composition coatings when adhesive resin composition-coated electrical steel sheets are stacked together, for example by being wound into a coil. This suppresses slow curing reactions within the adhesive resin composition coating and reactions between the adhesive resin composition coating and the adherend during storage, preventing adhesive performance degradation and adhesive blocking.

[0047] The thermocompression bonding process provides the following benefits: Rapid curing of the adhesive resin composition film during thermocompression bonding: By dissolving the curing agent remaining in a crystalline state during storage during thermocompression bonding, diffusion into the adhesive resin is promoted, enabling the adhesive resin composition film to cure in a short time. Furthermore, the crystalline state prevents dissolution of the curing agent, thereby suppressing the slow curing reaction within the adhesive resin composition film during storage. Therefore, a catalyst and / or accelerator that accelerates the reaction activation energy can be used in combination. Adding these may achieve both rapid curing of the adhesive resin composition film during thermocompression bonding and suppression of the slow curing reaction within the adhesive resin composition film during storage of the adhesive resin composition-coated electrical steel sheet. The use of a catalyst and / or accelerator that accelerates the reaction activation energy is not essential.

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

[0049] [Adhesive resin composition coating] 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 comprising an adhesive resin and a curing agent. An adhesive resin composition coating comprising a semi-cured product of a thermosetting adhesive resin composition can exhibit adhesive properties when heated and pressurized, so that adhesive resin composition-coated magnetic steel sheets can be bonded to each other by stacking and thermocompression bonding adhesive resin composition-coated magnetic steel sheets.

[0050] [Adhesive Resin Composition] The adhesive resin composition comprises an adhesive resin containing at least a thermosetting resin in part and a curing agent. The adhesive resin composition in the adhesive resin composition coating is in a semi-cured state where curing has progressed partially.

[0051] [Adhesive Resin] The adhesive resin exhibits thermosetting properties and therefore contains at least a thermosetting resin. As described above, the adhesive resin composition consists of an adhesive resin containing at least a thermosetting resin and a curing agent. Therefore, the adhesive resin refers to the components of the adhesive resin composition excluding the curing agent (unreacted curing agent). The thermosetting resin is a resin that undergoes three-dimensional polymer crosslinking and hardens when heated during use, possibly with the aid of a catalyst. In the adhesive resin composition coating, a portion of the thermosetting resin has undergone a crosslinking reaction with the curing agent, and the remainder remains unreacted.

[0052] [Curing 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 the curing agent crystallizes at room temperature. That is, a portion of the curing agent is present in a crystalline state in the adhesive resin composition coating. The curing agent used in the present invention may be any agent that can crystallize at room temperature and can exist in a crystalline state in the adhesive resin composition coating. Only a curing agent that can crystallize at room temperature may be used, or a curing agent that can crystallize at room temperature and a curing agent that does not crystallize at room temperature may be used in combination. Note that the curing agent in the adhesive resin composition coating refers to the unreacted curing agent component that has not reacted with the thermosetting resin.

[0053] In the present invention, whether or not a portion of the curing agent is present in a crystalline state in the adhesive resin composition coating is determined using a polarizing microscope. Because curing agent crystals have optical anisotropy, they appear bright when observed through polarizing filters arranged in a crossed Nicol configuration. On the other hand, because the adhesive resin is optically isotropic, they appear dark. Therefore, by using this difference, it is possible to distinguish between the adhesive resin phase, which is primarily composed of adhesive resin other than the curing agent crystals, and the curing agent crystals. Specifically, the adhesive resin composition coating coating on the steel sheet is observed in a cross section parallel to the steel sheet surface using a polarizing microscope. More specifically, examples of polarizing microscopes include an Olympus BX53M microscope or a Nikon LV150N upright microscope.

[0054] A polarizing filter (e.g., Olympus U-AN360-3, U-POTP3, etc.) is set in a crossed Nicol position, and observation is performed at 100 to 800 magnifications. The magnification can be appropriately selected within this range depending on the ease of identifying the curing agent crystal image. When a bright phase is observed, it is determined that a portion of the curing agent is present in a crystalline state in the adhesive resin composition coating.

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

[0056] [Amount of crystalline curing agent in adhesive resin composition film] The adhesive resin composition-coated electrical steel sheet of the present invention contains a certain amount of crystalline curing agent (curing agent crystals) in the adhesive resin composition film. The appropriate range of the residual amount of curing agent crystals in the adhesive resin composition film can be determined by the light scattering intensity utilizing the optical anisotropy of the curing agent crystals, i.e., the depolarized light (Hv) scattering intensity I. In the adhesive resin composition-coated electrical steel sheet of the present invention, the depolarized light scattering intensity (light amount) I of the adhesive resin composition film is 1.00 × 10 ７ ~50.00 x 10 ７ is.

[0057] Here, the depolarized light scattering intensity I of the adhesive resin composition coating is the depolarized light scattering intensity I measured on a 0.15 mm thick cover glass (e.g., cover glass No. 1 manufactured by Matsunami Glass Industry Co., Ltd.) that has been ultrasonically washed with detergent for 5 minutes or more. ０ (integrated value of the amount of light scattered at scattering angles from 0° to 22°) was measured, and the depolarized light scattering intensity measurement value I １ I ０ The normalized value, that is, I = I １ / I ０ is.

[0058] Depolarized light scattering intensity I is 1.00 x 10 ７If the depolarized light scattering intensity I is less than 50.00×10, most of the curing agent will dissolve and diffuse, making it impossible to suppress the slow curing reaction during storage, and it will be impossible to cure the adhesive resin composition film in a short time during thermocompression bonding. ７ If the curing agent is added in excess of 100 ppm, the curing reaction rate of the adhesive resin composition film is too slow, and the curing reaction does not proceed within a short time during thermocompression bonding. Furthermore, if an excess of curing agent is added, the depolarized light scattering intensity I also becomes excessive, and in this case, the strength and toughness of the adhesive resin composition film may be reduced.

[0059] From the viewpoint of ensuring adhesive blocking resistance and achieving short-time curing, the depolarized light scattering intensity I of the adhesive resin composition film is 1.05 × 10 ７ ~25.00 x 10 ７ is preferred, and 1.20 × 10 ７ ~18.00 x 10 ７ is more preferred.

[0060] The depolarized light scattering intensity I of the adhesive resin composition film can be measured by peeling the adhesive resin composition film from the steel plate and using a known light scattering intensity measurement method, specifically, using a light scattering measurement device equipped with a CCD camera (e.g., PP-1000 manufactured by Otsuka Electronics Co., Ltd.) that uses a He—Ne laser (λ=632.8 nm) as a light source and can set a polarizing filter in a crossed Nicol configuration. FIG. 1 is a diagram illustrating a method for measuring the depolarized light scattering intensity I of the adhesive resin composition film. As shown in FIG. 1, the adhesive resin composition film as a sample is placed between a light-emitter polarizing filter and a light-receiver 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 a two-dimensional detector (CCD camera).

[0061] A specific method for peeling the adhesive resin composition coating from the steel sheet involves immersing the adhesive resin composition-coated electrical steel sheet in a solution that dissolves the steel sheet, for example, an acid such as hydrochloric acid or nitric acid, or an alkaline solution such as sodium hydroxide, adjusted to a concentration that does not affect the adhesive resin composition coating. The steel sheet is then dissolved to peel the adhesive resin composition coating from the surface. Alternatively, the steel sheet may be mechanically cut to remove the adhesive resin composition coating. Here, "affecting the adhesive resin composition coating" refers to dissolving the curing agent crystals in the adhesive resin composition coating or decomposing the adhesive resin, thereby altering the adhesive resin composition coating. The method is not limited to these, as long as it can be peeled without affecting the adhesive resin composition coating as described above.

[0062] When the components and composition of the adhesive resin composition coating and the conditions for the steps of applying it to the steel plate and heating, drying, and solidifying it are given, a cast film of the adhesive resin composition having the same thickness as the steel plate coating and having been given the same amount of heat input as in the heating, drying, and solidifying step may be produced, 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 λ] The adhesive resin composition coating preferably has a softening onset temperature Tss of 50° C. or higher, as measured in the penetration mode of a thermomechanical analyzer (TMA) in accordance with JIS K 7196: 2012, and a maximum penetration λ of 15% or higher at 100 to 300° C. An adhesive resin composition coating that satisfies these softening onset temperatures and maximum penetration λ is in a state in which curing has progressed appropriately, and the following effects are obtained.

[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 reducing deterioration in adhesive ability. The upper limit of the softening start temperature Tss is not particularly limited, but is preferably 100°C or lower. If the softening start temperature Tss exceeds 100°C, the adhesive resin composition coating is hard even in a semi-cured state, which can slow the diffusion rate of the curing agent into the adhesive resin during the thermocompression bonding process and make short-term curing difficult. Alternatively, the thermocompression bonding process requires high temperatures of over 250°C, which can prolong heating and cooling times and reduce productivity.

[0065] By setting the maximum penetration λ to 15% or more, excessive hardening of the adhesive resin composition coating can be prevented, and the adhesive resin composition coating can be made to be more easily softened during thermocompression bonding.

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

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

[0068] Here, the softening onset temperature Tss and the maximum penetration λ will be described. FIG. 2 is a diagram illustrating a method for analyzing the softening onset temperature Tss and the maximum penetration λ of an adhesive resin composition film. The TMA curve shown in FIG. 2 is a typical TMA curve of an adhesive resin composition film of the present invention. The TMA curve can be obtained by measuring according to the method of JIS K 7196:2012, except that the adhesive resin composition film coated on a steel sheet is measured. As shown in FIG. 2, the softening onset temperature Tss is defined as the intersection of a line extending from the straight line on the lower temperature side where the needle (indenter) begins to penetrate toward the higher temperature side on the TMA curve, and a line extending from the tangent to the part where the needle penetration speed is maximum toward the lower temperature side.

[0069] The maximum needle penetration λ is defined as a percentage of the maximum needle penetration length (μm) divided by the thickness (μm) of the adhesive resin composition film ((maximum needle penetration length / thickness of adhesive resin composition film) × 100). The maximum needle penetration length (μm) can be determined from the TMA curve as shown in Figure 2. Note that the measurement was performed at 100% N. ２The adhesive resin composition coating thickness can be measured by cutting out a cross section of the adhesive resin composition-coated electrical steel sheet and observing it under a microscope.

[0070] [Glass transition temperature Tg of adhesive resin when uncured] The glass transition temperature Tg (Tg ｕｃ ) is preferably 30°C or higher. ｕｃ If the softening temperature is less than 30°C, depending on the softening onset temperature (glass transition temperature at the onset of softening, Tss) of the desired adhesive resin composition film, a large amount of heat must be input during heating, drying, and solidification after the adhesive is applied to the steel sheet, and a considerable amount of the thermosetting adhesive resin composition must be cured in order to form an adhesive resin composition film with a desired softening onset temperature (for example, 50°C or higher). To achieve this, it is necessary to dissolve most of the curing agent during heating, drying, and solidification and to diffuse it into the adhesive resin composition film, and it may be difficult to leave a certain amount of the curing agent in a crystalline state in the adhesive resin composition film.

[0071] In addition, the Tg of the adhesive resin ｕｃ The Tg of the adhesive resin is preferably 80°C or less. ｕｃ If the temperature exceeds 80°C, the viscosity of the adhesive applied to the steel sheet will be too high, making it difficult to apply the adhesive uniformly.

[0072] The Tg of the adhesive resin ｕｃ can be calculated from the following formula (Fox's formula) by identifying the composition (ingredients and blending) of the adhesive resin coating the steel sheet by nuclear magnetic resonance or pyrolysis gas chromatography.

[0073]

[0074] where ω i is the blending ratio (weight ratio) of component i, and Tg i is the glass transition temperature or softening onset temperature of component i. iIt can be determined by a known Tg or softening onset temperature measurement method, such as a method conforming to JIS K 7121:2012 or JIS K 7196:2012, using a differential scanning calorimeter (DSC) or a thermomechanical analyzer (TMA). Also, known values ​​described in manufacturer catalogs such as https: / / www.nscm.nipponsteel.com / epoxy / ec.html (as of April 2022) may be used.

[0075] The curing agent does not substantially vitrify, and the Tg of the adhesive resin ｕｃ Since the influence on the Tg of the adhesive resin composition is small, ｕｃ This is used as the Tg of the adhesive resin. ｕｃ The Tg of the adhesive resin composition ｕｃ The Tg can be determined by identifying the composition (components and blending) of the adhesive resin composition using nuclear magnetic resonance or pyrolysis gas chromatography, preparing a measurement sample with the same composition, and using a differential scanning calorimeter (DSC) according to a method in accordance with JIS K 7121:2012. The measurement sample can be prepared, for example, by a method described in the Examples. Specifically, the adhesive resin composition is appropriately diluted with a solvent to prepare a liquid thermosetting adhesive. This liquid thermosetting adhesive is cast on a glass plate and then vacuum-dried to prepare a cast film. The Tg (midpoint glass transition temperature) of the prepared cast film is measured according to a method in accordance with JIS K 7121:2012, and this is used as the Tg of the adhesive resin composition. ｕｃ This can be done.

[0076] [Thermosetting Resin] Specific examples of thermosetting resins include crosslinked 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 alone or in combination of two or more.

[0077] [Epoxy Resin] Epoxy resin is a resin containing two or more epoxy groups, which can be crosslinked with an appropriate curing agent to form a three-dimensional structure and harden. Examples of epoxy group-containing resins include bisphenol-based (bisphenol A, bisphenol F, bisphenol AD), naphthalene-based, and cardo-skeleton 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-alkoxymethylcarboxylate, allyl groups, and epoxy groups. Specific 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 the reactive functional groups, or crosslinked and cured by the reaction of the reactive functional groups with curing agents such as amines.

[0079] [Urethane Resin] Examples of urethane resins include resins composed of residues of polyfunctional isocyanate compounds and hydroxyl group-containing compounds. Specific examples include resins composed of 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 residues of hydroxyl group-containing compounds such as polyether polyol, polyester polyol, polyacrylate polyol, and polycarbonate polyol. Urethane resins can be crosslinked and cured by reaction with a curing agent such as an isocyanate-based curing agent or a polyol-based curing agent.

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

[0081] [Other Thermosetting Resins] Phenolic resins include resins containing two or more phenols (e.g., phenol, cresol, etc.). Examples include resins composed of residues of phenols and formaldehydes or aldehydes. Specific examples include phenol novolac resins, cresol novolac resins, cresol naphthol formaldehyde polycondensates, and triphenylmethane-type polyfunctional phenyl resins. Phenol aralkyl resins are also included. Melamine resins include alkyl-etherified melamine resins and their substituted derivatives. Urea resins include ethylene urea resins. Thermosetting polyimide resins include resins composed of residues of polycarboxylic dianhydrides and diamine compounds. Specific examples include thermosetting polyimide resins such as maleimide polymers, bismaleimide polymers, aminobismaleimide polymers, and bismaleimide triazine polymers. These resins can also be cured by crosslinking with a curing agent.

[0082] [Suitable Examples of Thermosetting Resins] Among the above thermosetting resins, those having a glass transition temperature Tg ｕｃ The thermosetting resin preferably contains one or more selected from the group consisting of epoxy resin, acrylic resin, urethane resin, and unsaturated polyester resin, because there are many options for achieving a temperature of 30° C. or higher, the curing reaction is rapid at high temperatures, and the curing agent is easily dispersed. Among these, it is most preferable that the thermosetting resin contains an epoxy resin, from the viewpoints of economy, versatility, and ease of handling.

[0083] [Suitable examples of adhesive resins contained 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 the total content (total mass of these thermosetting resins / mass (total) of adhesive resins x 100 (%)) is preferably 50 mass% or more. Adhesive resins containing less than 50 mass% of these thermosetting resins may not be able to fully utilize the properties of these thermosetting resins. Among these, adhesive resins containing 50 mass% or more of epoxy resin are most preferred in terms of economy, versatility, and ease of handling.

[0084] The adhesive resin may contain a thermosetting resin, and may also contain organic or inorganic components other than the thermosetting resin. For example, the adhesive resin may 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; an anti-rust agent; a lubricant; an antioxidant; an anti-foaming agent; a coloring pigment, etc.

[0085] [Examples of Curing Agents] Specific examples of curing agents include amine-based, amide-based, imidazole-based, acid anhydride-based, phenol-based, catalyst-based, etc. 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 the amine-based curing agent include, but are not limited to, aliphatic amines, aromatic amines, and guanidine compounds.

[0087] [Aliphatic Amines] Examples of aliphatic amines include, but are not limited to, 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 Amine] Examples of aromatic amines include, but are not limited to, diaminodiphenylmethane, m-phenylenediamine, diaminodiphenylsulfone (DDS), diethyltoluenediamine, trimethylenebis(4-aminobenzoate), polytetramethyleneoxide-di-p-aminobenzoate, methylaniline, and dimethylaniline.

[0089] [Guanidine Compound] 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] [Amide-Based Curing Agent] The amide-based curing agent is not limited to the following, but examples thereof include an amine-based curing agent to which an acid anhydride is added, and a hydrazide-based compound.

[0091] [Hydrazide Compounds] Examples of hydrazide compounds include, but are not limited to, succinic acid dihydrazide, adipic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, p-oxybenzoic acid hydrazide, salicylic acid hydrazide, phenylaminopropionic acid hydrazide, and maleic acid 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 (CEMI). 11 Z) and the like.

[0093] [Acid Anhydride Curing Agent] Examples of acid anhydride 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 phenol-based 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 co-condensed novolac resins, naphthol-cresol co-condensed 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]undec-7-ene.

[0096] The curing agent preferably 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, because this allows for a fast curing reaction rate of the adhesive resin composition coating during thermocompression bonding, thereby enabling relatively easy curing of the adhesive resin composition coating in a short time. Among these, 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 are preferred, because this increases the temperature at which the curing reaction of the resin composition coating most easily proceeds. The use of such curing agents allows for a difference between the storage temperature of the adhesive resin composition-coated electrical steel sheet and the heating temperature during thermocompression bonding, making it easier to control the temperature rise rate during thermocompression bonding. From the perspectives of ease of handling and versatility, the curing agent most preferably 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] It should be noted that the adhesive resin composition coating of the adhesive resin composition-coated electrical steel sheet of the present invention only needs to contain the above-mentioned specific amount of curing agent in a crystalline state, and the types of adhesive resin and curing agent are not limited to those examples given above.

[0098] [Thickness of Adhesive Resin Composition-Coated Electrical Steel Sheet] 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. Note that this is simply the thickness range of commonly available 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 film thickness of the adhesive resin composition coating in the adhesive resin composition-coated electrical steel sheet 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 will not be able to sufficiently penetrate into the surface irregularities of the adherend, making it difficult to exhibit an anchoring effect. If it exceeds 10 μm, the volume ratio of the adhesive resin composition coating to the laminated core will be too high, and the magnetic properties of the laminated core may be reduced.

[0100]

[0033] <Production Method> A method for producing an adhesive resin composition-coated electrical steel sheet that uses a preferred adhesive resin composition coating and achieves both good blocking suppression and sufficient adhesion will be described below. However, the method for producing an adhesive resin composition-coated electrical steel sheet of the present invention is not limited to the production method described below.

[0101] The method for producing an adhesive resin composition-coated electrical steel sheet of the present invention can be a production method 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 heating, drying and solidification step of heating the steel sheet to which the thermosetting adhesive has been applied and then cooling it to form an adhesive resin composition coating on the surface of the steel sheet.

[0102] [Adhesive Application Step] The adhesive application step is a step of applying a liquid thermosetting adhesive containing an adhesive resin and a curing agent to at least one surface of the steel plate.

[0103] [Thermosetting Adhesive] The thermosetting adhesive that can be used in the production of an adhesive resin composition-coated electrical steel sheet is a liquid containing an adhesive resin and a curing agent, and may contain, in addition to the thermosetting resin and curing agent, a thermoplastic resin; impact modifiers such as core-shell rubber and natural rubber; curing accelerators such as dimethylurea, boron trifluoride, and triphenylphosphine; known epoxy resin modifiers; reaction control agents (such as catalysts); surfactants; rust inhibitors; lubricants; antioxidants; antifoaming agents; coloring pigments, etc., depending on the composition of the adhesive resin composition coating (semi-cured product) to be formed.

[0104] The thermosetting adhesive can be used as is if the adhesive resin composition that constitutes the adhesive resin composition coating is liquid in an uncured state, but if it is not liquid or if it is necessary to adjust the viscosity, a solvent is added to use it as a liquid composition containing the adhesive resin composition and the solvent. Examples of solvents that can be used 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] The thermosetting adhesive can be used as a liquid consisting of the adhesive resin composition (the adhesive resin composition itself), a liquid obtained by diluting the adhesive resin composition with a solvent, a liquid obtained by dispersing the adhesive resin composition in an emulsion state in a solvent, etc. The thermosetting adhesive may be a one-component type in which the adhesive resin and the curing agent are mixed during the manufacturing stage of the thermosetting adhesive, or a two-component type in which the adhesive resin and the curing agent are stored separately and mixed immediately before application.

[0106] The viscosity of the thermosetting adhesive is preferably 100 to 1500 mPas. If the viscosity is less than 100 mPas, it is difficult to apply the adhesive resin composition to a desired thickness. On the other hand, if the viscosity exceeds 1500 mPas, it is difficult to apply the adhesive composition uniformly and in a short time, and thickness unevenness occurs in the width and length directions, further reducing productivity.

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

[0108] The thermosetting adhesive is preferably a dispersion in which at least a portion of the curing agent is dispersed, 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 is difficult, and the entire curing agent often dissolves due to the heat applied during the heat-drying and solidification process. In this case, the unreacted curing agent that did not react with the thermosetting resin due to the heat is unlikely to recrystallize even if it becomes supercooled during the cooling process following the heat-drying and solidification process, due to the absence of nucleating curing agent crystals. For this reason, it may be difficult to retain a predetermined amount of curing agent in a crystalline state in the adhesive resin composition film. Furthermore, if the particle size exceeds 20 μm, it is difficult to form a thin adhesive resin composition film of 10 μm or less on the surface of the steel sheet.

[0109] (Adhesive Application Method) The specific application method of the thermosetting adhesive is appropriately selected according to the properties of the thermosetting adhesive and is not particularly limited. For example, the application method can be performed by a roll coater method, a gravure coater method, an air doctor coater method, a blade coater method, a knife coater method, a rod coater method, a kiss coater method, a bead coater method, a cast coater method, a rotary screen method, a dip coating method in which a steel sheet is coated while immersed in a liquid thermosetting adhesive, or a slot orifice coater method in which a liquid thermosetting adhesive is dropped onto a steel sheet through an orifice to coat it.

[0110] In addition to these, other methods such as curtain coating, spray coating in which a liquid thermosetting adhesive is sprayed in mist using the principle of an atomizer, ink jet coating, and electrodeposition coating can also be used.

[0111] [Heat, Dry, and Solidify Process] The heat, dry, and solidify process is a process in which a steel sheet coated with a thermosetting adhesive is heated and then cooled to form an adhesive resin composition coating on the surface of the steel sheet. By heating, a portion of the thermosetting resin and a portion of the curing agent in the thermosetting adhesive coated on the steel sheet surface react and harden, forming a semi-cured adhesive resin composition. When a solvent-containing thermosetting adhesive is used, by heating, a portion of the thermosetting resin and a portion of the curing agent react, and the solvent in the thermosetting adhesive evaporates, forming a semi-cured adhesive resin composition. Furthermore, a portion of the curing agent may not dissolve during heating or may recrystallize upon cooling after heating. This results in an adhesive resin composition coating in which a predetermined amount of curing agent is dispersed in a crystalline state.

[0112] (Heating Method) As the heating (baking) method, known heating and drying (baking) methods can be used, such as hot air drying, induction heating, infrared heating, and vacuum heating.

[0113] As a result of investigations conducted by the present inventors, it was found that in order to keep the depolarized light scattering intensity I of the adhesive resin composition film within the above-mentioned range, it is extremely important to control the heating (drying) conditions of the heating temperature (T) and heating time. Specifically, it is necessary to set the heating temperature T within the temperature range of 100 to 250°C, and to control the heating time according to the type of thermosetting adhesive used so as to satisfy the following formula (i): 0.8≦t / t ０ ≦18.0 (i) where the meanings of the symbols in the formula (i) are as follows: t: heating time in the heating, drying and solidifying step t ０ : The time required to form an adhesive resin composition coating having a softening starting temperature (Tss) of 50°C when the thermosetting adhesive is dried at temperature T

[0114] t / t ０ By making the value of the depolarized light scattering intensity I equal to or greater than 0.8, the depolarized light scattering intensity I can be increased to 50.00×10 ７ The following can be set: ０ By making the value of the depolarized light scattering intensity I equal to or less than 1.00×10 ７ Here, the time t ０is determined as follows: First, a thermosetting adhesive is applied to the surface of a steel sheet. Then, the steel sheet is heated at a temperature T for various times, and the Tss of the adhesive resin composition film formed on the steel sheet is measured by the method described above. From the measurement results, the heating time required to achieve Tss = 50°C at the heating temperature T is calculated, and this is called t ０ Let's say.

[0115] (Cooling Method) After heating the steel sheet coated with a thermosetting adhesive, any known cooling method can be used. Air cooling, water cooling, mist cooling, or laminar flow cooling can all be used in combination, and some of these methods can be used intermittently. The cooling rate is preferably 1 to 600°C / min. If the cooling rate is less than 1°C / min, the curing reaction of the adhesive resin composition progresses during cooling, making it difficult to leave a predetermined amount of curing agent crystals, or forming an adhesive resin composition coating with a maximum penetration λ of less than 15%. On the other hand, if the cooling rate exceeds 600°C / min, the cooling rate becomes uneven across different regions, and thermal stress resulting from the difference in linear expansion coefficients between the steel sheet and the adhesive resin is concentrated in the rapidly cooled region, potentially resulting in a deterioration in the magnetic properties of the steel sheet.

[0116] <Preferred Manufacturing Method> Furthermore, the depolarized light scattering intensity I is 1.20 × 10 ７ ~18.00 x 10 ７ In order to ensure the adhesive blocking resistance and achieve short-time curing, the Tg of the adhesive resin is ｕｃ is set to 30°C or higher, the heating temperature in the heating, drying and solidifying step is set to a temperature T within the temperature range of 100 to 190°C, and the heating time is controlled depending on the type of thermosetting adhesive used so as to satisfy the following formula (ii): 1.3≦t / t ０ ≦15.0 (ii) where the meanings of the symbols in the formula (ii) are as follows: t: heating time in the heating, drying and solidifying step t ０ : The time required to form an adhesive resin composition coating having a softening starting temperature (Tss) of 50°C when the thermosetting adhesive is dried at temperature T

[0117] If you want to make the softening starting temperature Tss 70°C or higher, t / t ０is preferably 2.0 or more, and when it is desired to set the softening starting temperature Tss to 70°C or more, t / t ０ It is preferable that t / t is 8.0 or less. ０ is preferably 8.0 or less.

[0118] <Method of Use> (Method of Storage of Adhesive Resin Composition-Coated Magnetic Steel Sheet) Because the adhesive resin composition-coated magnetic steel sheet of the present invention has an appropriate amount of curing agent remaining in a crystalline state within the adhesive resin composition coating, it can be stored at room temperature and humidity without strict temperature and humidity control. Furthermore, even when transported by ship, adhesive blocking and adhesive blocking can be prevented, and deterioration of adhesive ability can be suppressed. Therefore, it can be stored using known steel sheet storage methods. Specifically, the adhesive resin composition-coated magnetic steel sheet can be wound into a coil or cut into sheets and laminated, and stored at room temperature and humidity, either packaged in paper or resin, or unpackaged. For longer storage periods, it can also be stored at low temperatures in a refrigerator or freezer.

[0119] <Manufacturing of Iron Core> The adhesive resin composition-coated electrical steel sheet of the present invention can be used to manufacture an iron core. For example, the adhesive resin composition-coated electrical steel sheet of the present invention is punched and sheared, laminated, and then thermocompression-bonded to manufacture an iron core. The iron core is also sometimes called an adhesive core, a motor core, etc.

[0120] (Punching and shearing method) The adhesive resin composition-coated electromagnetic steel sheets can be processed and laminated using known punching and shearing methods. Specifically, adhesive resin composition-coated electromagnetic steel sheets are continuously fed into a mold from a coil-shaped adhesive resin composition-coated electromagnetic steel sheet. At this time, processing oil is sprayed onto the adhesive resin composition-coated electromagnetic steel sheets just before they are loaded into the mold. Then, while feeding the adhesive resin composition-coated electromagnetic steel sheets into the mold, they are punched into desired shapes multiple times in sequence, and when all the desired shapes have been processed, they are sheared. Then, the sheared adhesive resin composition-coated electromagnetic steel sheets are dropped into a receiver in the mold and laminated, for example.

[0121] (Thermocompression bonding method) An iron core made of laminated adhesive resin composition-coated electromagnetic steel sheets can be pressure-bonded in a mold, or the iron core made of laminated adhesive resin composition-coated electromagnetic steel sheets can be removed from the mold and placed in a heating device for pressure application. Known heating methods can be used for heating. Specifically, methods that can be used include hot air heating using a hot air heat flow from an oven or the like, electrical resistance heating using resistance heating, low-frequency or high-frequency induction heating using induction power, and infrared heating using radiant heat (near-infrared or far-infrared). Among these, heating using a near-infrared heater is preferred. Heating using a near-infrared heater has a fast heater response speed and can heat with a high energy density, allowing the iron core to be heated rapidly. As a result, it is relatively easy to heat the iron core to the curing temperature without significantly promoting 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 as long as the gist of the present invention is not changed.

[0123] <Test Materials> [Steel Plate] A non-oriented electrical steel plate with a thickness of 0.35 mm was used. [Thermosetting Adhesive] The raw materials used in the thermosetting adhesive are shown in Table 1. The formulation of the adhesive resin composition is shown in Table 2. The values ​​shown in Table 2 are the blending amounts (parts by mass) of each raw material when the total amount of epoxy resin is 100 parts by mass.

[0124]

[0125]

[0126] <Formulation of adhesive resin composition, production of thermosetting adhesive> An adhesive resin composition was prepared by blending resin raw materials, additives, curing agents, and curing accelerators according to the compositions shown in Table 2. A solvent was then added to the adhesive resin composition so that the solids concentration in the liquid was 40 mass %, and the resulting 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 ｕｃMeasurement of Tg (midpoint glass transition temperature)> The thermosetting adhesive was cast onto a glass plate and then placed in a desiccator for 24 hours and dried at normal pressure. This was followed by a further 48 hours of vacuum drying at room temperature to remove the solvent. After vacuum drying, the cast film was recovered from the glass plate and heated at 5°C / min using a differential scanning calorimeter (DSC) (manufactured by Hitachi High-Tech Science Corporation) to measure the glass transition temperature (Tg) (midpoint glass transition temperature) in the uncured state in accordance with JIS K 7121:2012. The results are shown in Table 2.

[0128] Example 1: Manufacturing of Adhesive Resin Composition-Coated Electrical Steel Sheet 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 of the non-oriented electrical steel sheet (200 x 200 mm) using a roll coater (manufactured by Furnace Co., Ltd.) so that the film thickness after drying was 4.5 μm. After application, the sheet was dried at 140°C for 2.5 minutes to remove the solvent, forming an adhesive resin composition coating. After drying, cooling water was sprayed onto the steel sheet surface and the sheet was cooled to room temperature to obtain an adhesive resin composition-coated electrical steel sheet. The steel sheet temperature was measured using a thermocouple attached to the overlap portion of the steel sheet surface.

[0129] Examples 2 to 14 Adhesive resin composition-coated electrical steel sheets were obtained in the same manner as in Example 1, except that the thermosetting adhesives and drying conditions shown in Tables 3 to 5 were used.

[0130] <Confirmation of crystalline curing agent> The adhesive resin composition-coated electrical steel sheets immediately after drying were observed using a polarizing microscope using the method described above to determine whether a portion of the curing agent was present in a crystalline state in the adhesive resin composition coating. As a result, it was confirmed that a portion of the curing agent was present in a crystalline state in the adhesive resin composition coating, except for Comparative Example 2 described below.

[0131] <Measurement of Light Scattering Intensity> Immediately after drying, the adhesive resin composition coated magnetic steel sheet was immersed in hydrochloric acid to dissolve the steel sheet portion and peel off the adhesive resin composition coating.

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

[0133] The depolarized light scattering intensity (I ) of the adhesive resin composition coating film collected from the cover glass No. 1 manufactured by Matsunami Glass Industry Co., Ltd., and the adhesive resin composition coated electromagnetic steel sheet and cast film, respectively, was measured. ０ , I １ , the integral value of the amount of scattered light at scattering angles of 0° to 22°) was measured using a light scattering measuring device (PP-1000 manufactured by Otsuka Electronics Co., Ltd., with the distance (L) between the sample and the two-dimensional detector set to 20 cm). From this measurement value, I = I １ / I ０ was calculated and designated as the depolarized light scattering intensity I of the adhesive resin composition film. ０ and I １ Both values ​​were the average of three samples.

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

[0135] <Tss, λ, t ０Measurement of adhesive resin composition coating thickness> Test specimens were cut from the adhesive resin composition-coated electrical steel sheet immediately after drying and embedded in epoxy resin. After the epoxy resin cured, the steel sheet was polished to obtain a smooth cross section. The steel sheet cross section was observed under a microscope, and the thickness of the adhesive resin composition coating was measured. Furthermore, a 7 x 7 mm test specimen was cut out and placed in a sample tube for the penetration mode of a thermomechanical analyzer (TMA, manufactured by Hitachi High-Tech Science Corporation) with the adhesive-coated surface facing up. The specimen was heated in the penetration mode from -50°C to 300°C at a rate of 5°C / min. The penetration depth of the TMA probe needle into the adhesive resin composition coating coated on the steel sheet surface was then measured. Tss was calculated based on this data. Furthermore, the maximum needle penetration depth was determined based on this data, and λ was calculated. The results are shown in Tables 3 to 5.

[0136] Furthermore, samples were prepared by applying a thermosetting adhesive to the surface of an electromagnetic steel sheet so that the film thickness after drying would be 4.5 μm, and drying times were varied at 140°C. The needle penetration length into the adhesive resin composition film was measured under the same conditions using a TMA penetration mode, and the correlation between drying time and Tss was determined when drying was performed at the temperatures shown in Tables 3 to 5. From this data, the time t ０ The results are shown in Tables 3 to 5.

[0137] <Adhesive Blocking Test> Two 50 x 50 mm adhesive resin composition-coated electrical steel sheets were cut immediately after drying and stacked so that the adhesive surfaces overlapped by 40 x 50 mm. The stacked steel sheets were pressurized at 50°C at 8 MPa for 30 minutes. After unloading, a precision spring balance was used to measure the tensile shear bond strength between the adhesive surfaces and evaluated according to the following criteria. The greater the adhesive blocking between the adhesive composition resin layers, the greater the tensile shear bond strength. Therefore, the adhesive blocking resistance was evaluated using the following scale (A>B>C>D indicates prevention effect). Each measurement was performed five times. 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 adhesive resin composition-coated electrical steel sheets were cut immediately after drying and laminated so that the adhesive surfaces overlapped by 40 x 50 mm. The laminated steel sheets were pressurized at 8 MPa and placed in an oven (relative humidity 90%) set to a sheet temperature of 50°C for 12 weeks. After 12 weeks, the laminated steel sheets were removed from the oven and unloaded. After unloading, the tensile shear bond strength between the adhesive surfaces was measured using a precision spring balance. As adhesive blocking between the adhesive composition resin layers progressed during storage, the tensile shear bond strength increased. Therefore, the adhesive blocking resistance was evaluated using the following scale (A>B>C>D indicates prevention effect). Measurements were performed five times for each. A: 0.1 kPa or less, B: more than 0.1 kPa and less than 0.5 kPa, C: more than 0.5 kPa and less than 1 kPa, D: more than 1 kPa.

[0139] <Short-time curing in thermocompression bonding process> Two 100 x 25 mm adhesive resin composition-coated electrical steel sheets were cut immediately after drying and stacked so that the adhesive surfaces overlapped by 25 x 25 mm. The stacked steel sheets were pressurized at 1 MPa, heated to 200 °C at 5 °C / s, and held at 200 °C for 1 minute. After cooling to room temperature, the tensile shear bond strength before storage was measured in accordance with JIS K 6850:1999 (adhesion strength immediately after drying). Furthermore, a similar tensile shear bond strength test was performed using adhesive resin composition-coated electrical steel sheets stored in an oven (relative humidity 90%) at 50 °C for 12 weeks, and the tensile shear bond strength after storage was measured (adhesion 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]

[0141]

[0142]

[0143] Comparative Examples 1 to 3 Adhesive resin composition-coated electrical steel sheets were 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, and further, an adhesive blocking test, an adhesion blocking test, and the possibility of short-time curing in the thermocompression bonding step were evaluated.

[0145]

[0146] Comparative Example 4: A high molecular weight epoxy prepolymer (Mn = 6000) was prepared using bisphenol A epoxy (Epicoat 828 manufactured by Mitsubishi Chemical Corporation) in accordance with Example 43 of JP-A-11-162724. Next, an acrylic resin consisting of methacrylic acid, styrene, and ethyl acrylate (mass ratio: 174 / 87 / 29) was polymerized. 200 parts of the acrylic resin were dissolved in 267 parts of the high molecular weight epoxy prepolymer in a solvent, and then an amine 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 solids content of 25%. 5 parts of phenolic resin (bisphenol A resol type phenolic resin) and 20 parts of DICY were added to the emulsion per 100 parts of the resin in the emulsion to obtain an epoxy emulsion adhesive (thermosetting adhesive 6). The thermosetting adhesive 6 was then applied to the surface of the electrical steel sheet using a bar coater, dried for 10 minutes at 200°C within the sheet temperature range described in paragraph 0057 of the published patent application, and cooled to obtain an adhesive resin composition-coated electrical steel sheet.

[0147] Using the resulting 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, and an adhesive blocking test was also conducted, and the possibility of short-time curing in the thermocompression bonding step was evaluated. As a result, the light scattering intensity was approximately <1 × 10 6 As in Comparative Examples 2 and 3, the adhesive blocking resistance and adhesive strength after storage were D.

[0148] <Results> From Examples 1 to 14, it was found that magnetic steel sheets coated with an adhesive resin composition film made of a semi-cured product of the adhesive resin composition, in which the amount of curing agent crystals was controlled to a predetermined amount, were able to suppress adhesive blocking and adhesive blocking even when stored for a long period of time in a high-temperature, humid environment, and were able to cure in a short time during the thermocompression bonding process and exhibit adhesive strength.

[0149] On the other hand, Comparative Example 1 shows that when the light scattering intensity is outside the upper limit, sufficient adhesive strength cannot be obtained even when thermocompression-bonded immediately after drying. This is presumably due to the presence of curing agent crystals remaining in the adhesive resin composition coating even after thermocompression-bonding. Comparative Examples 2 to 4 show that when the light scattering intensity is outside the lower limit, adhesive blocking occurs during storage and adhesive strength after storage also decreases. This is presumably due to the curing agent dissolved during drying undergoing a slow curing reaction during storage. Furthermore, Comparative Example 4 shows that the adhesive resin composition-coated electrical steel sheet of the present invention cannot be easily manufactured using a known adhesive and a known method. Furthermore, because the components are outside the range of the present invention, adhesive blocking occurs during storage and adhesive strength after storage also decreases, as in Comparative Examples 2 and 3.

[0150] From a comparison of Examples 1, 2, and 8 with other Examples, it was found that the light scattering intensity was 18.60 × 10 ７ In the above cases, the adhesive strength immediately after drying was slightly low. Furthermore, in Examples 1, 2, and 8, the adhesive strength after storage was also slightly low. This is presumably because some curing agent crystals remained in the adhesive resin composition film even after thermocompression bonding, and these crystals became the starting point for the decrease in strength, causing the decrease in adhesive strength.

[0151] Furthermore, from a comparison of Examples 5, 10, 11, and 14 with other Examples, it was found that the light scattering intensity was 1.00×10 ７ ~1.10 x 10 ７ The adhesive blocking resistance tends to be slightly deteriorated in the case of the adhesive resin composition coated with the curing agent dissolved in the heating, drying and solidification process. This is presumably due to the slow curing reaction between the adhesive resin composition coatings progressing during storage.

[0152] Furthermore, when Examples 5 and 6 are compared, although Tss is the same, Example 6 has better adhesion blocking resistance than Example 5. This is presumably due to the following. In Example 5, the Tg ｕｃ In Example 6, the Tg of the adhesive resin composition 1 used was less than 30°C. ｕｃis 30°C or higher. As a result, in order to make Tss 80°C in the heating, drying, and solidification step, a greater heat input is applied in Example 5. As a result, it is presumed that a greater amount of the curing agent in Example 5 dissolved in the heating, drying, and solidification step. In fact, the area ratio of the curing agent crystals is also smaller in Example 5. Therefore, it is presumed that in Example 5, where a greater amount of the curing agent was dissolved, a slow curing reaction was more likely to proceed during storage, resulting in slightly inferior adhesive blocking resistance.

[0153] Furthermore, from a comparison of Example 1 with Examples 2 to 4, 6, 7, 9, and 14, it was found that the heat resistance was 1.1×t at 140°C. ０ The adhesive resin composition coated electrical steel sheets dried in less than 15.0 × t hours were inferior in adhesive blocking resistance. This is presumably due to the adhesive resin composition not being sufficiently cured after drying. Furthermore, a comparison of Example 14 with Examples 2 to 4, 6, 7, and 9 shows that the adhesive resin composition was not sufficiently cured after drying at 140°C for 15.0 × t hours. ０ The adhesive resin composition coated electrical steel sheet dried within 15.0×t hours has excellent adhesive blocking resistance. ０ When the sample was dried for more than 1 hour, the dissolution of the hardener crystals proceeded during the heating, drying and solidification process, and it is presumed that this was due to the slow hardening reaction caused by the hardener that had dissolved during storage.

[0154] According to the present invention, an adhesive resin composition-coated electrical steel sheet can be obtained that can prevent adhesive blocking and a decrease in 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 thermocompression 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.) for home appliances (air conditioners, vacuum cleaners, audio equipment, etc.) and motors for automobiles (HVs, EVs, etc.).

Claims

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

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

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

4. The thermosetting resin includes at least one selected from an epoxy resin, an acrylic resin, a urethane resin, and an unsaturated polyester resin. An adhesive resin composition-coated electrical steel sheet according to claim 1 .

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

6. A method for producing an adhesive resin composition coated electrical steel sheet according to any one of claims 1 to 4, comprising the steps of: a coating step of coating a liquid thermosetting adhesive containing the adhesive resin and the curing agent on at least one surface of the steel plate; and a heating, drying and solidification process in which the steel plate coated with the thermosetting adhesive is heated and then cooled to form an adhesive resin composition coating on the surface of the steel plate. The heating temperature in the heating, drying and solidifying step is a temperature T in the range of 100 to 250° C., The heating time in the heating, drying and solidifying step satisfies the following formula (i): A method for manufacturing an electrical steel sheet coated with an adhesive resin composition. 0.8≦t / t ０ ≦18.0 ・・・(i) In the above formula (i), the meanings of the symbols are as follows: t: heating time in the heating, drying and solidifying step t ０ : the time required to form an adhesive resin composition coating having a softening starting temperature of 50° C. when the thermosetting adhesive is dried at the temperature T

7. The glass transition temperature Tg of the adhesive resin ｕｃ is 30° C. or higher, The heating temperature in the heating, drying and solidifying step is a temperature T in the range of 100 to 180° C., The heating time in the heating, drying and solidifying step satisfies the following formula (ii): A method for producing an adhesive resin composition-coated electrical steel sheet according to claim 6. .3ttt ０ ≦.... ・・・(ii) In the above formula (ii), the meanings of the symbols are as follows: t: heating time in the heating, drying and solidifying step t ０ : the time required to form an adhesive resin composition coating having a softening starting temperature of 50° C. when the thermosetting adhesive is dried at the temperature T

8. The adhesive resin contains at least one thermosetting resin selected from an epoxy resin, an acrylic resin, a urethane resin, and an unsaturated polyester resin in an amount of at least 50 mass% based on the total amount of the adhesive resin. A method for producing an adhesive resin composition-coated electrical steel sheet according to claim 6.

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