JP4283652B2 - Aqueous surface treatment liquid for electrical steel sheet, method for producing electrical steel sheet with insulation film using the same, and electrical steel sheet with insulation film - Google Patents

Description

  The present invention relates to an electrical steel sheet used for an iron core of a transformer or a rotary machine used in industrial electrical equipment, and more particularly to an electrical steel sheet with an insulating film excellent in rust prevention of a buttocks and a manufacturing method thereof. It is.

  Electrical steel sheets are used as iron core materials for electric devices such as motors and transformers. When using an electrical steel sheet as an iron core for electrical equipment, the electrical steel sheet provided with an insulating film is punched into a predetermined shape, laminated, and then subjected to welding or caulking. In some cases, after the electromagnetic steel sheet is punched, strain relief annealing is performed to improve magnetic properties.

  Electrical steel sheets are manufactured as coils in steel manufacturers by coating an insulating film consisting of inorganic components such as dichromate and phosphate and organic resin emulsions, and then in the slitting process in electrical equipment manufacturers or slitting contractors. A punching process, a welding / caulking process, a cutting process, and the like are performed to obtain a product. As described above, since the electromagnetic steel sheet undergoes many processes until commercialization, there are cases where slag and handling slag (hereinafter, scouring and handling sushi are simply referred to as sushi) enter the insulating film on the steel sheet surface. There is a problem that rust may be generated from such wrinkles as a starting point during storage, resulting in a decrease in product quality.

  There have been some studies on the scratch resistance and rust resistance of insulating coatings used in electrical steel sheets. Regarding scratch resistance, for example, in Patent Document 1, chromic acid, dichromic acid, an organic resin having a Tg in the range of 10 ° C. to 100 ° C., and a predetermined amount of an organic reducing agent are disclosed in Patent Document 1. There is disclosed a method for improving the scratch resistance of an insulating film by containing. Further, Patent Document 2 improves the punchability and the adhesion at the time of slitting by adding Si and / or Ti-based coupling agent in the range of 0.1 to 5% by weight in the insulating film component. A method for improving the scratch resistance of an insulating film is disclosed.

  However, in the above-described invention, although there is an effect of making the insulating film difficult to be scratched, there is no description about the rust preventive property of the buttocks in the event of a crack.

  Moreover, about the rust prevention property of an electromagnetic steel sheet, it is reported by the nonpatent literature 1 that the surface oxide film composition and Si content in steel which are between an original plate and an insulating film influence rust prevention property. . According to this, when the Si content in the steel is low, or when a surface oxide film containing more Si, Al, and Mn that is annealed at a high dew point is formed, the antirust property is excellent. However, in the present situation where manufacturing is performed with various steel components and annealing conditions (many of which are continuous annealing) according to the grade of the electrical steel sheet, intentionally ensuring favorable annealing conditions for rust prevention properties. However, there is a problem that it is difficult to secure the magnetic characteristics that are the original characteristics of the electrical steel sheet and to consider the production aspect.

  Furthermore, Patent Document 3 discloses a method for improving rust prevention by appropriately controlling the residual amount of the organic reducing agent in the insulating film in the electrical steel sheet having the insulating film containing chromate. ing. However, in order to properly control the residual amount of the organic reducing agent, it takes time for water cooling to exceed the water cooling of the products currently in production, which has a problem of adversely affecting productivity. . Moreover, since improvement of product quality is requested | required now compared with those days, higher level rust prevention property is calculated | required.

Japanese Patent No. 3109203 JP-A-3-243780 JP 2000-192249 A Iron and steel S246 (1977) p. 246 Yoshitaka Hirosaki Kazuo Nakamura

  The present invention has been made in view of the above problems, and insulation generated on the insulating film surface and the insulating film surface without changing the annealing conditions of the electrical steel sheet or the inorganic component and organic resin component in the insulating film. Aqueous surface treatment solution for electrical steel sheet used for forming an insulation film of an electrical steel sheet with an insulation film having excellent rust prevention properties at the coating heel, a method for producing an electrical steel sheet with an insulation film using the same, and an insulation film The main purpose is to provide a magnetic steel sheet with a core.

  In order to achieve the above object, the present inventors have examined the addition of a rust preventive agent in the insulating film in order to obtain excellent rust prevention properties in the insulating film collar of the electromagnetic steel sheet with an insulating film. A rust inhibitor was added to a conventional aqueous surface treatment solution for electrical steel sheets containing an inorganic component that is mainly effective for insulation and an organic resin emulsion that is mainly effective for punchability. The antirust property of the electrical steel sheet with an insulating film was evaluated. In addition, the stability (gelation, precipitation, foaming, etc.) of the aqueous surface treatment solution for electrical steel sheets as a chemical solution was also investigated.

  As a result, it is an indispensable requirement for use in the aqueous surface treatment liquid for electrical steel sheets (1) Disperse or dissolve in the aqueous surface treatment liquid for electrical steel sheets, (2) have aging stability of chemicals, (3) Insulating coating As a rust inhibitor satisfying the three items of having thermal stability at the time of baking when forming a rust inhibitor, a rust inhibitor containing at least one of S, N and P having an unshared electron pair was found. Further, among them, a cyclic compound having a mercapto group has been found to be suitable as a rust inhibitor, and the present invention has been completed.

  That is, the present invention is an aqueous steel sheet surface treatment solution containing an inorganic component, an organic resin emulsion, and a rust preventive agent, wherein the rust preventive agent is at least one of S, N, and P having an unshared electron pair. An aqueous steel surface treatment solution for an electrical steel sheet characterized by containing any of the above is provided.

  According to the present invention, since the insulating film is formed using the aqueous surface treatment liquid for an electromagnetic steel sheet having the rust preventive agent as described above, the electromagnetic steel sheet with the insulating film having the insulating film is excellent in rust prevention. It can be. Therefore, without changing the manufacturing conditions of the electrical steel sheet with an insulating film, or the inorganic components contained in the aqueous surface treatment liquid for the electrical steel sheet, the organic resin emulsion, etc., it is possible to form an insulating film having rust resistance, This has the advantage that the choice of materials to be used is widened.

  In the said invention, it is preferable that the said rust preventive agent is a cyclic compound which has a mercapto group. When an insulating film is formed on a magnetic steel sheet using the aqueous surface treatment liquid for the magnetic steel sheet according to the present invention, iron ions that are inevitably eluted from the corroded magnetic steel sheet even if the insulating film is corroded and the magnetic steel sheet corrodes. This is because the mercapto group and the mercapto group form an insoluble salt, so that a dense precipitation film can be formed on the surface of the electrical steel sheet, and the rust prevention can be improved. Moreover, since a cyclic compound is hard to change in quality at high temperature, it can make it excellent in rust prevention property even after forming an insulating film.

  Moreover, in the said invention, it is preferable that the cyclic compound which has the said mercapto group is contained within the range of 0.005 weight%-1 weight% in conversion of dry solid content in the said aqueous | water-based surface treatment liquid for electrical steel sheets. . If the content is less than the above range, sufficient rust prevention properties may not be obtained.If the content exceeds the above range, the rust prevention properties are saturated and not only disadvantageous in cost. This is because the water resistance and rust resistance may be lowered.

  Furthermore, in the said invention, it is preferable that pH of the said aqueous | water-based surface treatment liquid for electromagnetic steel sheets exists in the range of 6.5-10.0. This is because the cyclic compound having the mercapto group can be stably dissolved in a larger amount when the pH is in the above range.

  In the present invention, the inorganic component is preferably at least one selected from the group consisting of chromic acid, chromate, silicic acid, silicate, boric acid, and borate. This is because by containing these inorganic components, pH adjustment can be performed relatively easily when preparing the aqueous surface treatment liquid for electrical steel sheet of the present invention.

  The present invention also provides an electrical steel sheet with an insulating film, characterized by having an insulating film forming step of forming an insulating film by applying and baking the aqueous surface treatment liquid for an electromagnetic steel sheet on the magnetic steel sheet. Provide a method.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical steel sheet with an insulating film excellent in rust prevention property can be manufactured by forming an insulating film on an electrical steel sheet using the said aqueous | water-based surface treatment liquid for electrical steel sheets. Therefore, it is possible to produce a rust-proof electrical steel sheet without changing the production conditions of the electrical steel sheet with an insulation film or the inorganic components and organic resin emulsions contained in the aqueous surface treatment liquid for electrical steel sheets. This has the advantage that the choice of materials to be used is widened.

  In the said invention, it is preferable not to perform water cooling after baking the said aqueous | water-based surface treatment liquid for electromagnetic steel sheets in the said insulating-film formation process, or to perform water cooling so that water cooling time may be 10 seconds or less. This is because if the water cooling time is longer than the above range, the rust inhibitor contained in the aqueous surface treatment liquid for electromagnetic steel sheets may be eluted in water, and sufficient rust prevention properties may not be obtained.

The present invention is also an electrical steel sheet with an insulating film having an insulating film containing an inorganic component, an organic resin component, and a rust inhibitor, and the electrical steel sheet with an insulating film is heated at 700 ° C. for 2 hours. Insulation characterized in that seizure and cracking of the insulating film are not observed, and the interlayer resistance measured by the interlayer resistance measuring method of JIS C 2550 is 1 Ω · cm ² / sheet or more. A coated electrical steel sheet is provided.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as an electromagnetic steel plate with an insulating film excellent in rust prevention property because an insulating film has a rust preventive agent and has predetermined heat resistance and insulation.

The present invention also relates to an electrical steel sheet with an insulating film having an insulating film containing an inorganic component, an organic resin component, and S (sulfur), and the electrical steel sheet with an insulating film is heated at 700 ° C. for 2 hours. However, seizure and cracking of the insulating film are not recognized, and the interlayer resistance measured by the interlayer resistance measuring method of JIS C 2550 is 1 Ω · cm ² / sheet or more. An electrical steel sheet with an insulating film is provided.

  Moreover, in the said invention, it is preferable that said S (sulfur) comprises a mercapto group. Even if the insulating film of the magnetic steel sheet with an insulating film of the present invention inevitably gets wrinkled and the magnetic steel sheet corrodes in a corrosive environment, the iron ions eluted from the magnetic steel sheet and the mercapto group are insoluble in this case. This is because it is considered that a dense precipitation film can be formed on the surface of the electromagnetic steel sheet and the rust prevention can be improved.

  According to the present invention, the water-based surface treatment liquid for an electromagnetic steel sheet used for forming the insulating film has a predetermined rust preventive agent, so that the manufacturing conditions of the electromagnetic steel sheet with the insulating film or the water-based surface treatment liquid for the magnetic steel sheet Without changing the inorganic component, organic resin emulsion, etc. contained in the insulating film, an insulating film having excellent rust prevention can be formed on the surface of the insulating film and the part of the insulating film generated on the surface of the insulating film. Therefore, an electromagnetic steel sheet with an insulating film excellent in rust prevention can be obtained, which is industrially useful.

  The present invention includes an aqueous surface treatment solution for an electrical steel sheet, a method for producing an electrical steel sheet with an insulating film using the same, and an electrical steel sheet with an insulating film. Hereinafter, each will be described in detail.

A. First, the aqueous surface treatment liquid for electrical steel sheets according to the present invention will be described.

  The aqueous surface treatment liquid for electrical steel sheets of the present invention contains an inorganic component, an organic resin emulsion, and a rust preventive agent, and the rust preventive agent is at least one of S, N, and P having an unshared electron pair. It contains.

  When an insulating film is formed on an electromagnetic steel sheet using the aqueous surface treatment solution for an electromagnetic steel sheet according to the present invention, excellent rust preventive properties can be obtained at the surface of the insulating film and the insulating film ridge generated on the surface of the insulating film.

  Here, the rust preventive agent contains at least one of S, N and P having an unshared electron pair, so that the rust preventive of the insulating film formed using the aqueous surface treatment liquid for electrical steel sheets of the present invention. The mechanism for improving the performance is not clear, but is considered as follows.

  That is, when the insulating film is inevitably creased and the steel sheet is corroded in a corrosive environment and the iron ions are eluted, the iron ions and the rust preventive S, N or P unshared electron pairs By bonding, a dense insulating film is formed on the surface of the electrical steel sheet, so that the rust prevention property is considered to be improved. For example, when the rust inhibitor has a mercapto group (-SH), the mercapto group (-SH) and iron ions form an insoluble salt, and this insoluble salt forms a dense precipitate film on the surface of the electrical steel sheet. is there. Further, it is considered that the rust preventive agent S, N or P unshared electron pair directly adsorbed to the surface of the magnetic steel sheet to form an insulating film contributes to the improvement of rust prevention. Therefore, when an insulating film is formed on a magnetic steel sheet using the aqueous surface treatment solution for an electromagnetic steel sheet of the present invention, it is possible to produce an electromagnetic steel sheet with an insulating film having excellent rust prevention properties.

  Conventionally, the rust prevention is improved by changing the types and amounts of inorganic components, organic resin emulsions, and organic reducing agents for reducing chromic acid, or the steel composition and annealing conditions of electrical steel sheets. However, in the present invention, it is possible to improve rust prevention without changing each of the above components, or the steel composition or annealing conditions of the electrical steel sheet, so that the aqueous surface treatment liquid for electrical steel sheet can be used. There is also an advantage that the choice of materials to be used is widened.

  Examples of the aqueous surface treatment liquid for electrical steel sheets according to the present invention include Japanese Patent No. 3109203, Japanese Patent Laid-Open No. 2000-192249, and “Iron and Steel” vol. 66 (7) (1980) p. 1000-1009 Aqueous surface treatment solution for electrical steel sheet mainly comprising at least one of chromic acid or chromate and an organic resin emulsion as disclosed in Motoharu Nakamura et al., Disclosed in JP-A-10-128903. Aqueous surface treatment liquid for electrical steel sheet mainly composed of silica and organic resin emulsion, and an aqueous surface for electrical steel sheet mainly composed of phosphate as disclosed in JP-A-6-330338 A processing liquid etc. are mentioned.

In the present invention, among the above, the water-based surface treatment liquid for electrical steel sheet mainly composed of at least one of chromic acid or chromate and the organic resin emulsion, and the water for electrical steel sheet mainly composed of silica and the organic resin emulsion. A system surface treatment liquid can be suitably used. This is because such an aqueous surface treatment liquid for electrical steel sheet is relatively easy to adjust pH. On the other hand, the aqueous surface treatment liquid for electrical steel sheets mainly composed of phosphate is often acidic, and as described later, the rust inhibitor may be stably dissolved and difficult to dissolve. It is necessary to select.
Hereinafter, each component of such an aqueous surface treatment liquid for electrical steel sheets will be described.

1. Inorganic component The inorganic component used in the present invention is not particularly limited as long as it is generally used in an aqueous surface treatment solution for electrical steel sheets for forming an insulating film. For example, a metal oxide or a metal oxide Or the like can be used. Specific examples include chromic acid, chromate, silicic acid, silicate, boric acid, borate, phosphoric acid, phosphate, silica, alumina, and the like. Moreover, you may use these inorganic components in combination of 1 type, or 2 or more types.

  In the present invention, among the above, at least one selected from the group consisting of chromic acid, chromate, silicic acid, silicate, boric acid, borate, and silica is used as the inorganic component. Is preferred. In particular, it is preferable to use at least one selected from the group consisting of chromic acid, chromate, silicic acid, silicate, boric acid, and borate. By containing these inorganic components, the pH adjustment of the aqueous surface treatment liquid for electrical steel sheet according to the present invention can be performed relatively easily as will be described later.

  In the present invention, chromic acid includes chromic acid and dichromic acid, and chromate includes chromate and dichromate.

As the above-mentioned chromic acid and chromates, other chromic acid represented by _{CrO 3, Al, Mg, Ba} , Ca, chromate such as Zn can be used. The same applies to the silicic acid and silicate, and the boric acid and borate.

  Further, as the above silica, a commercially available silica molecule (anion), generally called alkali silicate, in a form in which alkali metal or ammonia is neutralized, can be used. . Of these, lithium silicate and ammonium silicate are preferably used from the viewpoint of rust prevention. Further, in place of alkali silicate, colloidal silica, vapor phase silica or the like can be used.

  Moreover, as said alumina, colloidal alumina etc. can be used.

  When forming an insulating film excellent in heat resistance using the aqueous surface treatment solution for electrical steel sheets of the present invention, boric acid, borate, colloidal silica, vapor phase silica, colloidal alumina, etc. are used as the inorganic component. It is preferable to use it.

  The content of the inorganic component varies depending on the type of inorganic component, the type of organic resin emulsion described below, and the type of rust inhibitor, but 2% by weight in terms of dry solids in the aqueous surface treatment solution for electrical steel sheets. It is preferably contained within a range of ˜40% by weight, preferably within a range of 4% by weight to 30% by weight, particularly within a range of 6% by weight to 20% by weight. When the content of the inorganic component is less than the above range, in the electrical steel sheet with an insulating film having the insulating film formed using the aqueous surface treatment liquid for electrical steel sheet of the present invention, heat resistance and insulation may be insufficient. Because. In addition, when the content of the inorganic component is larger than the above range, the rust preventive property is saturated in the electrical steel sheet with an insulating film having the insulating film formed using the aqueous surface treatment liquid for the electrical steel sheet of the present invention, and the inorganic component is This is because if the content is large in the insulating film, the shrinkage force of the insulating film during dehydration and curing becomes too large, and the film properties may be deteriorated.

  In addition, in this invention, content by dry solid content conversion means content in the dry solid content of the aqueous | water-based surface treatment liquid for electrical steel sheets.

2. Next, the organic resin emulsion used in the present invention will be described. As the organic resin emulsion used in the present invention, an organic resin that is generally used in an aqueous surface treatment liquid for electrical steel sheets for forming an insulating film can be used. For example, acrylic resins such as acrylic resins, acrylic styrene resins, acrylic-ethylene resins, acrylic-propylene resins, acrylic-silicone resins, copolymers containing acrylic resins, urethane resins, vinyl acetate resins, epoxy resins Fluorine resin, melamine resin, phenol resin, polyester resin, silicon resin, and the like can be used. These organic resins may be used alone or in combination of two or more. In the present invention, among the above, acrylic resins and copolymers containing acrylic resins can be suitably used.

  In the present invention, as described later, since the aqueous surface treatment liquid for electrical steel sheets is preferably adjusted to have a predetermined pH, the organic resin emulsion is stable in a predetermined pH range. It is preferable to use what is.

  Here, in the present invention, the organic resin emulsion means organic resin fine particles dispersed in the aqueous surface treatment liquid for electrical steel sheet of the present invention.

  The particle size of the organic resin emulsion is preferably in the range of 0.05 μm to 1.0 μm. This is because when the particle size of the organic resin emulsion is larger than the above range, the stability in the aqueous surface treatment liquid for electrical steel sheets may be insufficient. Further, when the particle size is smaller than the above range, in the electrical steel sheet with an insulating film having an insulating film formed using the aqueous surface treatment liquid for electrical steel sheet of the present invention, the punchability may be reduced, and This is because a small diameter is difficult to obtain industrially and is disadvantageous in cost. Furthermore, when the emphasis is on the caulking property, it is preferable to use a material having a relatively small particle size, while when the emphasis is on slipperiness, it is preferable to use a material having a relatively large particle size. . As described above, the particle size of the organic resin emulsion may be appropriately selected in consideration of cost and chemical solution stability. For example, when the caulking property is important, the particle size is within a range of 0.1 μm to 0.5 μm. Is preferable, and in particular, it is preferable to be within a range of 0.1 μm to 0.3 μm.

  The content of the organic resin emulsion varies depending on the kind of the inorganic component, the kind of the organic resin emulsion, and the kind of the rust inhibitor described later, but in terms of dry solid content, with respect to 100 parts by weight of the inorganic component. It is preferably in the range of 1 to 50 parts by weight, particularly in the range of 5 to 35 parts by weight. When the content of the organic resin emulsion is less than the above range, in the electrical steel sheet with an insulating film having the insulating film formed using the aqueous surface treatment liquid for the electrical steel sheet of the present invention, the punchability may be lowered, and contained It is because heat resistance may fall when there is much quantity exceeding the said range.

3. Next, the rust inhibitor used in the present invention will be described. In the present invention, the rust preventive agent contains at least one of S, N and P having an unshared electron pair.

  When an insulating film is formed on a magnetic steel sheet using the aqueous surface treatment liquid for magnetic steel sheet of the present invention, the rust inhibitor contains at least one of S, N and P having an unshared electron pair, which is unavoidable. Even when the insulating film is wrinkled and the electrical steel sheet is corroded in a corrosive environment, the iron ions eluted from the corroded electrical steel sheet and the rust preventive S, N or P unshared electron pair , And a dense insulating film is formed on the surface of the electromagnetic steel sheet, which is considered to improve rust prevention.

  As such a rust preventive agent, as long as it contains at least one of S, N and P elements having an unshared electron pair, even if it is an inorganic rust preventive agent, an organic rust preventive agent It may be. For example, organic rust inhibitors include aliphatic hydrocarbons, aromatic hydrocarbons, aliphatic cyclic hydrocarbons or heterocyclic hydrocarbons as the basic skeleton, mercapto groups, sulfo groups, sulfonyl groups, sulfino groups, sulfinyl groups. A compound having at least one of substituents having S, N, and P elements such as a group, a thiocarboxyl group, a dithiocarboxyl group, a nitro group, an amino group, an amide group, a nitrile group, and a phosphono group; A compound having at least one of S, N and P elements in the basic skeleton of an aromatic cyclic hydrocarbon or heterocyclic hydrocarbon; within the basic skeleton of an aromatic hydrocarbon, aliphatic cyclic hydrocarbon or heterocyclic hydrocarbon A compound having at least one of S, N and P elements, which is a mercapto group, a sulfo group, a sulfonyl group, a sulfino group, Finiru group, thiocarboxyl group, dithiocarboxyl group, and a nitro group, an amino group, an amide group, a nitrile group, S such as a phosphono group, a compound having at least one substituent having N and P elements.

  In the present invention, among these, those having a mercapto group are preferable. As described above, even if the magnetic steel sheet is inevitably corroded by the insulating film, the iron ions eluted from the magnetic steel sheet and the mercapto group form an insoluble salt. This is because the salt forms a dense precipitate film on the surface of the magnetic steel sheet, and therefore can be excellent in rust prevention.

  Furthermore, in the present invention, a cyclic compound having a mercapto group is particularly preferable. Since cyclic compounds are less susceptible to alteration at higher temperatures compared to linear compound rust preventives, even after an insulating film is formed using the aqueous surface treatment liquid for electrical steel sheets of the present invention, sufficient prevention is achieved. This is because rustability can be obtained. In addition, when forming a precipitation film with an insoluble salt or an adsorption film on the surface of an electromagnetic steel sheet, it is considered that the rust preventive agent has a cyclic structure, so that the shielding effect is increased and the rust prevention performance is advantageously improved. Because.

  As such a cyclic compound having a mercapto group, a compound having a mercapto group and having a basic skeleton of an aromatic hydrocarbon, an aliphatic cyclic hydrocarbon or a heterocyclic hydrocarbon, and a mercapto group having an aromatic And compounds having at least one of S, N and P elements in the basic skeleton of the aromatic hydrocarbon, aliphatic cyclic hydrocarbon or heterocyclic hydrocarbon. Among them, in the present invention, a thiadiazole having a mercapto group and a triazole having a mercapto group are preferable. Specifically, 2,5-dimercaptothiadiazole, 3-methylmercapto-5-mercapto-1,2,4-thiadiazole, 2-mercapto-5-methyl-1,3,4-thiadiazole, 2-amino- 5-mercapto-1,3,4-thiadiazole, 3-mercapto-1,2,4-triazole, 3,5-dimercapto-1,2,4-triazole, 3-amino-5-mercapto-1,2, 4-triazole, 3-propyl-4-amino-5-mercapto-1,2,4-triazole and the like can be mentioned.

  The content of the rust inhibitor varies depending on the kind of the inorganic component, the kind of the organic resin emulsion, and the kind of the rust inhibitor, but is 0.0. It is preferably in the range of 005 wt% to 1 wt%, especially in the range of 0.05 wt% to 0.3 wt%, particularly in the range of 0.08 wt% to 0.2 wt%. In the case where the content is less than the above range, in the electrical steel sheet with an insulating film having the insulating film formed using the aqueous surface treatment liquid for electrical steel sheet of the present invention, there is a possibility that sufficient rust preventive property may not be obtained. is there. In addition, when the content exceeds the above range, the electrical steel sheet with an insulating film having an insulating film formed using the aqueous surface treatment solution for an electrical steel sheet of the present invention is saturated in rust prevention and disadvantageous in cost. This is because the water resistance and rust resistance of the insulating film may be reduced.

  In the present invention, the rust inhibitor is preferably water-soluble. Specifically, the solubility of the rust preventive agent in water is preferably 10 ppm or more, particularly 100 ppm or more at 20 ° C. This is because if the solubility is smaller than the above range, sufficient antirust property may not be obtained.

4). Others In the present invention, when the rust inhibitor is a cyclic compound having a mercapto group, the pH of the aqueous surface treatment liquid for electrical steel sheet is in the range of 6.5 to 10.0, particularly in the range of 7 to 9, particularly It is preferably within the range of 7-8. This is because the cyclic compound having a mercapto group can be stably dissolved in a larger amount when the pH of the aqueous surface treatment liquid for electrical steel sheet is in the above range.

  Moreover, in this invention, in order to improve stability of the said organic resin emulsion, you may add surfactant according to each component of the aqueous | water-based surface treatment liquid for electrical steel sheets. However, it is preferable to use a surfactant-free (soap-free) surfactant because it may adversely affect the coating workability due to foaming.

  Furthermore, in the present invention, when chromic acid is used as the inorganic component, for example, a reducing agent for reducing chromic acid may be added. By using a reducing agent, chromic acid can be reduced from hexavalent chromium to trivalent chromium. After applying an aqueous surface treatment solution for electrical steel sheets containing such a reducing agent, baking is performed. This is because an insulating film substantially containing no valent chromium can be obtained. If hexavalent chromium remains in the insulating film, water resistance and rust resistance may be reduced.

  As such a reducing agent, an alcoholic compound generally used as a reducing agent can be used. For example, ethylene glycol, methanol, glycerin, ethanol, 1,4-butanediol, 1,2,3,4-butanetetrol, polyethylene glycol and the like can be mentioned.

The amount of the reducing agent added is within the range of 10 to 100 parts by weight per 100 parts by weight in terms of chromic acid (CrO ₃ ) contained in chromic acid and chromate, especially 20 to 50 parts by weight. It is preferable to be within the range. The reducing agent is oxidized in the order of alcohol compound, organic acid, carbon dioxide and water, but some of the reducing agent is not completely oxidized and may remain as an organic acid. Since the remaining organic acid may deteriorate the rust prevention property of the insulating film collar, it is preferable that the residual amount of the organic acid is small. Therefore, in view of the rust prevention property of the insulating film formed using the aqueous surface treatment solution for electrical steel sheets of the present invention, it is preferable that the organic acid and its anion remaining in the insulating film are small. It is preferable to reduce the addition amount of the reducing agent while taking into consideration the baking conditions and the equipment capacity when forming.

  In the present invention, a metal oxide or hydroxide may be contained as an alkali for neutralizing the inorganic component. This is because, for example, when chromic acid is used as the inorganic component, the metal hydroxide has an effect of neutralizing chromic acid and stabilizing the organic resin emulsion. As such a metal hydroxide, oxides or hydroxides such as Al, Mg, Ba, Ca, Zn, and Li can be used. In general, Mg salt and Li salt are often used. These metal oxides or hydroxides are included in the inorganic component.

  Furthermore, when silica is used as the inorganic component, it may contain a weak acid component. When a commercially available product generally called alkali silicate is used as silica, the pH of the commercially available product is often 12 or more. By containing the weak acid component, the alkali silicate is neutralized and the organic resin emulsion is stabilized. Because it does. Examples of such weak acid components include acetic acid and boric acid. Of these weak acid components, those that volatilize and decompose such as acetic acid are not included in the inorganic component, but boric acid and the like are included in the inorganic component.

  Moreover, water is suitable as a solvent used for the aqueous | water-based surface treatment liquid for electrical steel sheets of this invention. However, in order to stabilize the organic resin emulsion, for example, an organic solvent such as alcohol or cellosolve may be included as required.

Here, the preparation method of the aqueous | water-based surface treatment liquid for electrical steel sheets of this invention is demonstrated.
First, a case where dichromate is mainly used as an inorganic component will be described as an example.

  Magnesium hydroxide is added to the dichromic acid aqueous solution to obtain a solution having a molar ratio of Mg / Cr = 0.5. At this time, calcium hydroxide may be used in place of part or all of the magnesium hydroxide. Next, an alkali is added to the aqueous solution to adjust the pH to about 7.5. At this time, if lithium hydroxide is used as the alkali, an insulating film having higher rust prevention property can be formed. A cyclic compound having a mercapto group is dissolved in the aqueous solution adjusted in pH as described above, and an organic resin emulsion is further added. Thereby, the water-system surface treatment liquid for electromagnetic steel sheets is obtained.

  When chromic acid is used as the inorganic component, ethylene glycol or glycerin may be added as a chromic acid reducing agent. Furthermore, when forming an insulating film having heat resistance, boric acid, colloidal silica, and vapor phase silica may be added.

  Next, a case where silica (alkali silicate) is mainly used as an inorganic component will be described as an example.

  Since the pH of commercial products of alkali silicate is often pH 12 or more as it is, a cyclic compound having a mercapto group after the pH is lowered by adding or diluting a weak acid component (for example, acetic acid or boric acid). A compound is added, and the organic resin emulsion is further dissolved to prepare an aqueous surface treatment solution for electrical steel sheets.

  Moreover, when forming the insulating film excellent in heat resistance, or adjusting pH, boric acid or a borate can also be used as an inorganic component. Furthermore, when using for the magnetic steel sheet with an insulation film which has heat resistance, you may add inorganic components, such as colloidal silica and colloidal alumina.

  In this invention, what used the phosphate as an inorganic component other than the aqueous | water-based surface treatment liquid for electromagnetic steel plates mentioned above is mentioned. However, the aqueous surface treatment solution for electrical steel sheets using phosphate as an inorganic component can only be obtained in the form of a first phosphate aqueous solution, and the solution becomes acidic, so it is weakly alkaline and easily dissolved stably. There may be a problem that the cyclic compound having a mercapto group is not easily dissolved stably. Therefore, when phosphate is used as the inorganic component, it is necessary to select a preferable rust inhibitor.

  Further, the concentration of the dry solid content in the aqueous surface treatment solution for electrical steel sheets of the present invention varies depending on the type of each component, but is within the range of 3 to 30% by weight, particularly 5 to 25% by weight. In particular, it is preferable to be within the range of 10% by weight to 20% by weight. The concentration may be appropriately adjusted by a coating method when the aqueous surface treatment solution for electrical steel sheets of the present invention is applied on the electrical steel sheet, but if the concentration is too low, the aqueous system for electrical steel sheets per unit area at the time of coating is used. This is because the amount of the surface treatment liquid increases and it is difficult to obtain a beautiful appearance. On the other hand, if the concentration is too high, the stability as a chemical liquid may be impaired.

  In the present invention, the dry solid content in the aqueous surface treatment liquid for electrical steel sheet refers to a component remaining after drying the aqueous surface treatment liquid for electrical steel sheet.

B. Next, the manufacturing method of the electrical steel sheet with an insulating film of the present invention will be described.

  The manufacturing method of the electrical steel sheet with an insulating film of the present invention includes an insulating film forming step of forming the insulating film by applying the above-described aqueous surface treatment liquid for electrical steel sheet onto the electrical steel sheet and baking it.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical steel sheet with an insulating film excellent in rust prevention property can be manufactured by forming an insulating film on an electrical steel sheet using the said aqueous | water-based surface treatment liquid for electrical steel sheets.

  In general, the method for producing an electrical steel sheet with an insulating film includes a slab heating process, a hot rolling process, a hot-rolled sheet annealing process, a cold rolling process, a continuous annealing process, and an insulating film forming process. In the present invention, among the above steps, the insulating film forming step is a step of forming the insulating film by applying the aqueous surface treatment liquid for electromagnetic steel sheet on the steel sheet and baking it. It is. Accordingly, the other steps can be performed by generally used methods and conditions.

  Hereinafter, the insulating film formation process in the manufacturing method of the electrical steel sheet with an insulating film of the present invention and the electrical steel sheet with an insulating film manufactured according to the present invention will be described.

1. Insulating film forming step In the method for producing an electromagnetic steel sheet with an insulating film of the present invention, an insulating film forming step is performed in which the above-described aqueous surface treatment liquid for an electromagnetic steel sheet is applied onto the electromagnetic steel sheet and baked to form an insulating film. .

  ADVANTAGE OF THE INVENTION According to this invention, the electrical steel sheet with an insulating film excellent in rust prevention property can be manufactured by forming an insulating film on an electrical steel sheet using the said aqueous | water-based surface treatment liquid for electrical steel sheets.

  In addition, since it is the same as that of what was described in the "A. Aqueous surface treatment liquid for electrical steel sheets" mentioned above about the aqueous surface treatment liquid for electrical steel sheets used for this process, description here is abbreviate | omitted.

  The method for applying the aqueous surface treatment liquid for an electromagnetic steel sheet may be any method that can be applied to the surface of the electromagnetic steel sheet, and examples thereof include roll coating, spray coating, curtain coating, and the like.

  Moreover, the said aqueous surface treatment liquid for electromagnetic steel plates may be apply | coated only to the single side | surface of an electromagnetic steel plate, and may be applied to both surfaces.

Further, the coating amount, in the range of 0.2g ^{/ m 2} ~4.0g ^/ m 2 on a dry solid basis, is preferably. This is because when the coating amount is less than the above range, the antirust property may be inferior or the insulating property may be insufficient. On the other hand, when the coating amount exceeds the above range, the adhesion between the electromagnetic steel sheet aqueous surface treatment liquid and the electromagnetic steel sheet may be reduced. In consideration of adhesion to the aqueous surface-treating liquid and the electromagnetic steel sheet for magnetic steel, it is preferred that the amount of coating among the above, in the range of ^{0.5g / m 2 ~2.0g / m 2} . Further, the coating amount and to consider the rust resistance is preferably better slightly ^more, preferably in the range of ^{1.0g / m 2 ~2.0g / m 2} .

  In addition, when an insulating film is formed on both surfaces of a magnetic steel sheet, the coating amount is an amount per one surface.

  As a baking temperature at the time of baking the said aqueous | water-based surface treatment liquid for electromagnetic steel plates, it is preferable to exist in the range of 150 to 350 degreeC in the highest ultimate temperature of an electromagnetic steel plate. When the baking temperature is smaller than the above range, when forming the insulating film, the dehydration reaction and condensation reaction of each component contained in the aqueous surface treatment liquid for electrical steel sheets may not sufficiently proceed, and the water resistance is This is because there is a risk of lowering. Moreover, when chromic acid or chromate is used as an inorganic component in the aqueous surface treatment liquid for electrical steel sheets, the reduction reaction of chromic acid may not proceed sufficiently. On the other hand, when the baking temperature is larger than the above range, the organic resin emulsion or the organic rust preventive agent contained in the aqueous surface treatment liquid for electromagnetic steel sheets may be deteriorated or deteriorated. . In the present invention, from the viewpoint of the thermal stability of the organic resin emulsion and the heat resistance of the organic rust preventive agent, the baking temperature may be in the range of 150 ° C to 300 ° C in the above range. preferable.

  The baking time may be determined comprehensively from the size, length and productivity of the baking furnace and the performance of the insulating film. Specifically, it is preferably within a range of 5 seconds to 120 seconds, and more preferably within a range of 10 seconds to 60 seconds. This is because if the baking time is shorter than the above range, the rust prevention property of the insulating film or the adhesion between the electromagnetic steel sheet and the aqueous surface treatment liquid for the electromagnetic steel sheet may be lowered. Further, if the baking time is longer than the above range, productivity may be adversely affected.

  Usually, in the insulating film forming process, after baking the aqueous surface treatment liquid for an electromagnetic steel sheet, it is often rapidly cooled with water in order to suppress meandering and deformation of the electromagnetic steel sheet or damage to a rubber roll or the like. In the present invention, when the water cooling time is lengthened, the rust preventive agent contained in the aqueous surface treatment liquid for electromagnetic steel sheets may be eluted in water, so that the rust preventive property is not necessarily improved. Therefore, in the present invention, it is preferable not to perform water cooling if possible. When water cooling is performed, the water cooling time is preferably 10 seconds or less, and more preferably 5 seconds or less.

2. Next, the electrical steel sheet with an insulating film manufactured by the method for manufacturing the electrical steel sheet with an insulating film of the present invention will be described. The electrical steel sheet with an insulating film produced by the method for producing an electrical steel sheet with an insulating film of the present invention is obtained by forming an insulating film on the electrical steel sheet using the surface water-based surface treatment liquid for the electrical steel sheet. It is.

  According to the present invention, even when the surface water-based surface treatment liquid for electrical steel sheet contains a predetermined rust preventive agent, the magnetic steel sheet is inevitably corroded into the insulating film and corroded in the corrosive environment. Since the iron ions eluted from the corroded magnetic steel sheet and S, N or P of the rust preventive agent are combined to form a dense insulating film on the surface of the magnetic steel sheet, an insulating film with excellent rust resistance is provided. An electromagnetic steel sheet can be obtained.

  In addition, regarding the electromagnetic steel sheet and the insulating film in the electromagnetic steel sheet with an insulating film manufactured by the method for manufacturing the electromagnetic steel sheet with an insulating film of the present invention, the same as described in “C. Therefore, the description here is omitted.

C. Next, the electromagnetic steel sheet with an insulating film of the present invention will be described.

The electrical steel sheet with an insulating film of the present invention can be divided into two modes. As a 1st aspect, it is an electrical steel sheet with an insulation film which has an insulation film containing an inorganic component, an organic resin component, and a rust preventive agent, Comprising: It has predetermined heat resistance and insulation. Moreover, as a 2nd aspect, it is an electrical steel sheet with an insulating film which has an insulating film containing an inorganic component, an organic resin component, and S (sulfur), Comprising: It has predetermined heat resistance and insulation.
Each aspect will be described below.

1. 1st aspect First, the 1st aspect of the electromagnetic steel plate with an insulating film of this invention is demonstrated. A first aspect of the electrical steel sheet with an insulating film of the present invention is an electrical steel sheet with an insulating film having an insulating film containing an inorganic component, an organic resin component, and a rust inhibitor, and the heat resistance and the insulating properties are predetermined. It is within the range.

  According to this aspect, when the insulating film contains a rust preventive agent, excellent rust preventive properties can be obtained at the surface of the insulating film and the part of the insulating film generated on the surface of the insulating film. In addition, conventionally, by changing the type and amount of inorganic components, organic resin components, and organic reducing agents for reducing chromic acid, or the steel composition and annealing conditions of the electrical steel sheet, the rust prevention of the insulating film However, in the present invention, it is possible to improve rust prevention without changing each component in the insulating film as described above or the steel composition or annealing conditions of the electrical steel sheet. In addition, when manufacturing an electrical steel sheet with an insulating film, there is an advantage that the choice of materials to be used is widened. Furthermore, since it has predetermined heat resistance and insulation, rust prevention can be improved efficiently.

  In this embodiment, the heat resistance of the electrical steel sheet with an insulating film is that seizure and cracking of the insulating film are not observed even after heating at 700 ° C. for 2 hours.

  Here, the heat resistance is evaluated by carrying out soaking annealing for 2 hours in a nitrogen atmosphere at a predetermined temperature in which two electromagnetic steel sheets with insulating films are stacked. In the electrical steel sheet with an insulating film of this embodiment, no seizure occurs between the electrical steel sheets with an insulating film even after soaking at 700 ° C., and there is no cracking or missing of the insulating film. However, there is no significant peeling of the insulating film. In this embodiment, it is preferable that the above-mentioned phenomenon does not occur even in soaking at 750 ° C.

In this embodiment, the insulating property of the electrical steel sheet with an insulating film is that the interlayer resistance measured by the interlayer resistance measuring method of JIS C 2550 is 1 Ω · cm ² / sheet or more. Among these, in this embodiment, the interlayer resistance is preferably 5 Ω · cm ² / sheet or more, particularly preferably 10 Ω · cm ² / sheet or more.

  Furthermore, the punchability of the electrical steel sheet with an insulating film according to this aspect is different depending on the steel component of the electrical steel sheet, the component of the insulating film, and the manufacturing conditions, but it is sufficient that the punchability as a general electrical steel sheet is satisfied. . For example, a 15 mm square blank may be punched with a 5% clearance mold made of SKD11, and the increase in the flash height may not be seen extremely. In particular, if the number of times of punching until the flash height reaches 50 μm is 1 million times or more in the above-described punchability evaluation method, it can be used without any problem.

Furthermore, as described above, the weldability of the electrical steel sheet with an insulating coating according to the present embodiment varies depending on the steel component of the electrical steel sheet, the component of the insulating coating, and the manufacturing conditions, but the weldability as a general electrical steel sheet. As long as For example, TIG welding may be performed on the end surfaces of two superposed electromagnetic steel sheets with an insulating film, and a blow hole may not be generated in the weld bead portion at a welding speed of 60 mm / min or more.
Hereinafter, each structure of such an electromagnetic steel sheet with an insulating film will be described.

(1) Electrical steel sheet The electrical steel sheet used for the electrical steel sheet with an insulating film of the present embodiment is not particularly limited, and may generally be composed of steel components contained in the electrical steel sheet. Examples of the steel component include Si, Mn, P, Al, S, N, V and the like used for improving magnetic properties and other performances. The balance of the electrical steel sheet is substantially made of Fe and inevitable impurities.

  As a kind of electromagnetic steel sheet, non-directionality is common, but either unidirectional or bi-directional may be used.

  Moreover, in order to form a uniform insulating film on the electromagnetic steel sheet, pretreatment such as pickling, alkali cleaning, and brushing may be performed.

(2) Insulating film Next, the insulating film used in this embodiment will be described. In this embodiment, the insulating film contains an inorganic component, an organic resin component, and a rust inhibitor.

According to this aspect, when the insulating film contains a rust preventive agent, excellent rust preventive properties can be obtained at the surface of the insulating film and the part of the insulating film generated on the surface of the insulating film.
Hereinafter, each component of such an insulating film will be described.

(I) Inorganic component As an inorganic component used for this aspect, the thing similar to what was described in the column of the inorganic component of "A. Aqueous surface treatment liquid for electrical steel sheets" mentioned above can be used.

  As content of the said inorganic component, although it changes also with the kind of inorganic component, the kind of organic resin component mentioned later, and the kind of rust preventive agent, in the range of 2 to 40 weight% in an insulating film, Preferably It is preferably in the range of 4 to 30% by weight, particularly in the range of 6 to 20% by weight. This is because if the content of the inorganic component is less than the above range, the heat resistance and insulation of the insulating film may be insufficient. Moreover, when there is more content of an inorganic component than the said range, while rust prevention property is saturated, there exists a possibility that film | membrane property may worsen for shrinkage | contraction at the time of spin-drying | dehydration.

  The content of the inorganic component may be a value calculated from the amount of the inorganic component contained in the aqueous surface treatment liquid for electrical steel sheet used when forming the insulating film, and is obtained by analyzing the insulating film. It may be a value. Examples of the method for analyzing the insulating film include a method in which the insulating film is dissolved by alkali melting and then quantified by emission analysis.

(Ii) Organic resin component Next, the organic resin component used in this embodiment will be described. As an organic resin component used in this embodiment, an organic resin generally used for an insulating film can be used. As such an organic resin, the same organic resin as that described in the column of the organic resin emulsion of “A. Aqueous surface treatment liquid for electromagnetic steel sheet” described above can be used.

  As content of the said organic resin component, although it changes also with the kind of said inorganic component, the kind of organic resin component, and the kind of rust preventive agent mentioned later, 1 weight part-50 weight with respect to 100 weight part of said inorganic components. It is preferably within the range of 5 parts by weight to 35 parts by weight. This is because if the content of the organic resin component is less than the above range, the punchability may be reduced, and if the content exceeds the above range, the heat resistance may be reduced.

  The content of the organic resin component may be a value calculated from the amount of the organic resin component contained in the aqueous surface treatment liquid for electrical steel sheet used when forming the insulating film. It is good also as an obtained value. Examples of the method for analyzing the insulating film include a method in which the insulating film is isolated by acid dipping or the like and quantified by temperature rising gas analysis or the like. In addition, a sample for a calibration curve is prepared in advance, and a nondestructive method using an infrared absorption spectrum or the like can also be used.

(Iii) Rust preventive agent Next, the rust preventive agent used in this embodiment will be described. As the rust preventive agent used in this embodiment, the same rust preventive agent as described in the column of the rust preventive agent of “A. Aqueous surface treatment liquid for magnetic steel sheet” described above can be used.

The content of the rust inhibitor varies depending on the kind of the inorganic component, the kind of the organic resin component, and the kind of the rust inhibitor, but in the insulating film, 0.005% by weight to 1% by weight,
Among these, 0.05% by weight to 0.3% by weight is preferable. This is because if the content of the rust inhibitor is less than the above range, there is a possibility that sufficient rust prevention properties may not be obtained. Moreover, when there is much content exceeding the said range, it is because not only rust prevention property is saturated and it is disadvantageous in cost, but the water resistance and rust prevention property of an insulating film may fall.

  The content of the rust inhibitor may be a value calculated from the amount of the rust inhibitor contained in the aqueous surface treatment liquid for electrical steel sheet used when forming the insulation film. It is good also as an obtained value.

(Iv) Others In this aspect, the insulating film may be formed only on one side of the electromagnetic steel sheet, or may be formed on both surfaces of the electromagnetic steel sheet.

Further, the adhesion amount to the electromagnetic steel sheet insulating coating is preferably in the range of 0.2g ^{/ m 2} ~4.0g ^/ m 2 as the total coating weight. This is because when the amount of the insulating film deposited is less than the above range, the antirust property may be inferior or the insulating property may be insufficient. On the other hand, when the adhesion amount of the insulating film is larger than the above range, the adhesion between the insulating film and the electrical steel sheet may be lowered. In consideration of adhesion to the insulating and electrical steel sheet, it is preferred coating weight of the insulation coating among the above, in the range of ^{0.5g / m 2 ~2.0g / m 2} . Further, the adhesion amount of rust resistance of the insulating coating consider preferably better slightly more, and particularly preferably in the range of ^{1.0g / m 2 ~2.0g / m 2} .

  In addition, when an insulating film is formed on both surfaces of a magnetic steel sheet, the amount of the insulating film attached is the amount per one surface.

2. 2nd aspect Next, the 2nd aspect of the electromagnetic steel plate with an insulating film of this invention is demonstrated. A second aspect of the electrical steel sheet with an insulating film of the present invention is an electrical steel sheet with an insulating film having an insulating film containing an inorganic component, an organic resin component, and S (sulfur), and has a predetermined heat resistance and insulating property. It is what has.

  Hereinafter, each structure of such an electromagnetic steel sheet with an insulating film will be described. In addition, regarding the characteristics such as heat resistance and insulation properties of the electrical steel sheet with an insulating film and the electrical steel sheet in this aspect are the same as those in the first aspect described above, description thereof is omitted here.

(1) Insulating film In this aspect, an insulating film contains an inorganic component, an organic resin component, and S (sulfur).

  Hereinafter, each component of the insulating film will be described. Note that the inorganic component and the organic resin component are the same as those in the first aspect described above, and thus the description thereof is omitted here.

(I) S (sulfur)
This embodiment is characterized in that S is contained in the insulating film.

  In this embodiment, it is preferable that S constitutes a mercapto group. In this case, the compound having a mercapto group is preferably contained in the insulating film. Even if the insulation film of the electrical steel sheet with an insulation film of the present invention is inevitably wrinkled and the electrical steel sheet is corroded in a corrosive environment, the iron ions eluted from the corroded electrical steel sheet and the mercapto group ( This is because -SH) forms an insoluble salt, and this insoluble salt forms a dense precipitate film on the surface of the magnetic steel sheet, so that rust prevention can be improved.

  In addition, about the compound which has a mercapto group, since it is the same as that of what was described in the column of the antirust agent of "A. aqueous | water-based surface treatment liquid for electrical steel sheets" mentioned above, description here is abbreviate | omitted.

  Here, the fact that S (sulfur) is contained in the insulating film can be measured using, for example, fluorescent X-rays.

(Ii) Others In this embodiment, the insulating film may be formed only on one side of the electromagnetic steel sheet, or may be formed on both sides.

  In addition, since it is the same as that of the 1st aspect mentioned above regarding the adhesion amount of an insulating film, description here is abbreviate | omitted.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

[Examples 1 to 16]
As the electrical steel sheet, a steel sheet having the composition shown in Table 1 was subjected to cold rolling to a thickness of 0.5 mm, and then annealed at 800 ° C. for 15 seconds in a 50% hydrogen + 50% nitrogen atmosphere. A steel plate was used.

  After applying the following aqueous surface treatment liquid for an electromagnetic steel sheet to both surfaces of the electromagnetic steel sheet, it was baked at a maximum temperature of 300 ° C. for 30 seconds and then allowed to cool to room temperature. Thereby, an electromagnetic steel sheet with an insulating film was obtained.

(Preparation of aqueous surface treatment solution for electrical steel sheets)
Magnesium hydroxide was added to the dichromic acid aqueous solution to prepare 800 g of an aqueous solution in which 140 g of magnesium dichromate (Mg / Cr molar ratio = 0.5) was dissolved in water. In this aqueous solution, 28 g of boric acid and 20 g of ethylene glycol were dissolved, and further 2 g of a nonionic pluronic surfactant having a solid concentration of 50% by weight was dissolved. Next, lithium hydroxide was added to the aqueous solution to adjust the pH to 7.5. The amount of lithium hydroxide added was 30 g. Furthermore, 2,5-dimercaptothiadiazole (MTD) was dissolved in an arbitrary amount within a range of 0.002 g to 3.5 g. To the above solution, 42 g of an acrylic styrene emulsion dispersion having a solid concentration of 50% by weight as a solid content was added and stirred. Furthermore, water was added to 1000 g to prepare an aqueous surface treatment liquid for electrical steel sheets.

  It was found that the solid content concentration of the obtained aqueous surface treatment liquid for electrical steel sheets was 16% by weight after measurement after drying the aqueous surface treatment liquid for electrical steel sheets at 150 ° C. for 2 hours.

  In addition, solid content concentration here shows content of the component (dry solid content) which dried after the water-system surface treatment liquid for electrical steel sheets.

[Example 17]
An electrical steel sheet with an insulating coating was prepared in the same manner as in Examples 1 to 16, except that an aqueous surface treatment solution for electrical steel sheet in which 0.4 g of phosphonic acid was dissolved was used instead of 2,5-dimercaptothiadiazole (MTD). Was made.

[Comparative Example 1]
Magnetic steel sheets with insulating coatings were produced in the same manner as in Examples 1 to 16, except that 2,5-dimercaptothiadiazole (MTD) was not added to the aqueous surface treatment liquid for magnetic steel sheets.

[Comparative Examples 2 and 3]
Insulating film in the same manner as in Examples 1 to 16, except that instead of 2,5-dimercaptothiadiazole (MTD), 0.4 g of vanadic acid or molybdic acid was used, an aqueous surface treatment solution for electrical steel sheets was used. An attached magnetic steel sheet was produced.

  It shows in Table 2 about the electromagnetic steel plate with an insulating film of the said Examples 1-17 and Comparative Examples 1-3.

[Examples 18 to 29]
Using the same magnetic steel sheets as in Examples 1 to 16, the following aqueous surface treatment liquid for magnetic steel sheets was applied to both surfaces of the magnetic steel sheets, and then baked at a maximum temperature of 280 ° C. for 45 seconds. Further, after baking, it was quickly cooled with water. At this time, the water cooling time was changed within the range of 0 to 25 seconds. Thereby, an electromagnetic steel sheet with an insulating film was obtained.

(Preparation of aqueous surface treatment solution for electrical steel sheets)
To 500 g of an aqueous lithium silicate solution (SiO ₂ / Li ₂ O = 4.5) having a solid content concentration of 20% by weight, 300 g of ion-exchanged water was added and dissolved. A 10% aqueous acetic acid solution was added to this aqueous solution to adjust the pH to 9.5. Next, 5 g of boric acid was dissolved in the aqueous solution, and 2 g of a nonionic pluronic surfactant having a solid concentration of 50% by weight was dissolved. Further, 3,5-dimercapto-1,2,4-triazole (MTA) is dissolved in an arbitrary amount within a range of 0.06 g to 0.5 g, and an acrylic styrene emulsion dispersion having a solid content concentration of 50% by weight is dissolved. Was added and stirred. Water was added to the above solution to 1000 g to prepare an aqueous surface treatment solution for electrical steel sheets.

  It was found that the solid content concentration of the obtained aqueous surface treatment liquid for electrical steel sheets was 12% by weight by measuring the aqueous surface treatment liquid for electrical steel sheets after drying at 150 ° C. for 2 hours.

  In addition, solid content concentration here shows content of the component (dry solid content) which dried after the water-system surface treatment liquid for electrical steel sheets.

[Examples 30 to 33]
Instead of 3,5-dimercapto-1,2,4-triazole (MTA), an aqueous surface treatment solution for electrical steel sheet in which 0.7 g or 1.5 g of phosphonic acid was dissolved was used, and the water cooling time was 0 second to An electrical steel sheet with an insulating film was produced in the same manner as in Examples 18 to 29 except that the time was within the range of 10 seconds.

[Comparative Examples 4 to 7]
Instead of 3,5-dimercapto-1,2,4-triazole (MTA), a water-cooling time of 0 to 10 seconds was used using an aqueous surface treatment solution for electrical steel sheets in which 0.5 g or 1 g of vanadic acid was dissolved. An electrical steel sheet with an insulating film was produced in the same manner as in Examples 18 to 29, except that the thickness was within the range.

  Table 3 shows the electrical steel sheets with insulating coatings of Examples 18 to 33 and Comparative Examples 4 to 7.

[Evaluation]
The following evaluation was performed about the electrical steel sheet with an insulating film of Examples 1-33 and Comparative Examples 1-7. The evaluation results are shown in Table 2 and Table 3.

(Chemical solution stability)
100 ml of the aqueous surface treatment solution for electrical steel sheets was collected in a beaker, put in a commercially available homomixer, stirred for 10 minutes at 10000 rpm, and after 5 minutes, the foamed state of the aqueous surface treatment liquid for electrical steel sheets and generation of solid matter The condition was investigated. In addition, (double-circle) and (circle) were made favorable.
A: Foaming has disappeared. There is no solid matter.
○: Foaming remains. There is no solid matter.
Δ: Foaming remains. There is a solid.
X: Gelled.

(Amount of insulation coating)
Using a fluorescent X-ray apparatus, the amount of Cr deposited on the insulating coating surface (in the case of Mg dichromate insulating coating) or the amount of Si deposited (in the case of lithium silicate insulating coating) was measured. From this value, the amount of Cr or Si in the aqueous surface treatment solution for electrical steel sheets was converted into the amount of the insulating film deposited using the ratio of the total solid content.

(water resistant)
The magnetic steel sheet with an insulating film was cut out to 70 mm × 150 mm, the end face was sealed with a polyester tape, immersed in hot water at 50 ° C. for 8 hours, and the immersed part and the non-immersed part were visually evaluated. In addition, (double-circle) and (circle) were made favorable.
(Double-circle): There is no difference in a state by an immersion part and a non-immersion part.
○: The immersion part was slightly whitened.
(Triangle | delta): Red rust generate | occur | produced in a part of immersion part.
X: Red rust occurred on the entire surface of the immersion part.

(Adhesion)
The magnetic steel sheet with an insulating film was cut out to 50 mm × 150 mm, the magnetic steel sheet with an insulating film was bent along a round bar of φ2 mm, φ4 mm, and φ6 mm, and a tape peeling test was performed on the bent outer side. The insulating film on the tape surface was visually evaluated. In addition, (double-circle) and (circle) were made favorable.
A: The insulating film did not peel at all.
○: There was a peeled insulating film on the φ2 mm round bar, but it was not peeled off on the φ4 mm and φ6 mm round bars.
Δ: There was an insulating film peeled off on the round bars of φ2 mm and φ4 mm, but it was not peeled off on the round bar of φ6 mm.
X: There was an insulating film peeled off at all.

(Stone rust prevention test)
A magnetic steel sheet 3 with an insulating film having an electromagnetic steel sheet 1 and an insulating film 2 as shown in FIG. 1 (a) is cut out to 70 mm × 150 mm, and the length is formed on the surface of the insulating film 2 as shown in FIG. 1 (b). Five 50 mm ridges 4 were attached. Moreover, the depth of the ridge 4 was set to a depth until the electromagnetic steel sheet 1 was reached. At this time, only the insulating film on one side of the electrical steel sheet with the insulating film was wrinkled. As shown in FIG. 1 (c), the electromagnetic steel sheet with an insulating film is overlapped with two electromagnetic steel sheets 5 with no wrinkles, and three sheets are stacked, and four corners are clipped, A set was made. This electrical steel sheet set was exposed to a constant temperature and humidity chamber adjusted to 50 ° C. and 95% RH for 100 hours. After the exposure, the magnetic steel sheet assembly was opened, and the number of rust generated around the buttock was counted. Counting was performed on five wrinkles, and the average value was calculated. From this average value, the buttocks rust prevention property was evaluated as follows. In addition, (double-circle) and (circle) were made favorable.

<Rust prevention evaluation criteria>
個数 Number of rust generated per 50 mm 疵 Average value of 5: Number of rust is within 3 ○: Number of rust is within 10 △: Number of rust is within 30 ×: Number of rust is 31 Xx: The number of rust is 51 or more

(Heat-resistant)
Two sheets of magnetic steel sheets with an insulating film having a width of 30 mm and a length of 280 mm were stacked and subjected to soaking for 2 hours under a predetermined temperature and nitrogen atmosphere. The following evaluations were made based on the soaking annealing temperature at which the specimens did not seize after soaking, there was no cracking or missing of the insulating film, and there was no significant peeling of the insulating film in the tape peeling test. did.
A: 800 ° C. or higher ○: 700 ° C. or higher and lower than 800 ° C. ×: lower than 700 ° C.

(Insulation)
The interlayer resistance was measured by the interlayer resistance measuring method specified in JIS C 2550, and the average value of all 10 measured values was measured.
◎: 10 Ω · cm ² / sheet or more ○: 1 Ω · cm ² / sheet or more ×: 1 Ω · cm ² / sheet or less

  As shown in Table 2, in the magnetic steel sheets with insulating coatings of Examples 4 to 15, the content of the rust inhibitor was an appropriate amount, and the buttock rust resistance was good. Among them, the electrical steel sheets with insulating coatings of Examples 6 to 10 had an appropriate amount of the rust preventive agent, and were particularly excellent in the balance of the buttock rust preventive property, water resistance, adhesion, heat resistance and insulation. . Moreover, since the electrical steel sheet with an insulation film of Examples 1-3 has little content of a rust preventive agent, a buttock rust prevention property is somewhat inferior, and the electrical steel sheet with an insulation film of Examples 14-16 is anti-corrosion. Due to the high content of rusting agent, water resistance was slightly degraded. Furthermore, in the rust preventive agent used in Example 17, the buttocks rust preventive property was slightly poor. On the other hand, the magnetic steel sheet with an insulating film of Comparative Example 1 had a poor rust preventive property due to the absence of a rust inhibitor. In addition, the rust preventive agent used in Comparative Examples 2 and 3 could not obtain the buttock rust preventive property.

  In addition, as shown in Table 3, the electrical steel sheets with insulating coatings of Examples 18 to 29 had an appropriate amount of addition of the rust inhibitor and good buttock rust prevention properties. Among them, the electrical steel sheets with insulating films of Examples 18 to 20, 22, 23, and 26 to 28 have a particularly short balance of rust prevention, water resistance, adhesion, heat resistance, and insulation properties because of a short water cooling time. It was excellent. Moreover, in the rust preventive agent used in Examples 30 to 33, the buttock rust preventive property was slightly inferior. On the other hand, with the rust preventive agent used in Comparative Examples 4 to 7, the buttock rust preventive property was not obtained.

It is explanatory drawing for demonstrating a buttocks rust prevention test.

Claims (10)

An aqueous surface treatment liquid for electrical steel sheets containing an inorganic component, an organic resin emulsion, and a rust inhibitor,
The inorganic component comprises a silicate or an alkali silicate;
The rust inhibitor, S having an unshared electron pair, are those containing at least one of N and P, and you characterized electrical steel plates aqueous surface to be a cyclic compound having a mercapto group Treatment liquid.   The aqueous surface treatment solution for an electrical steel sheet according to claim 1, wherein the silicate or alkali silicate is lithium silicate. The water for electrical steel sheets according to claim 1 or 2 , wherein the cyclic compound having a mercapto group is 2,5-dimercaptothiadiazole or 3,5-dimercapto-1,2,4-triazole. Surface treatment solution. Wherein the cyclic compound having a mercapto group, claim 1, characterized in that contained in the range of 0.005% to 1% by weight on a dry solid basis on the aqueous surface-treating liquid for magnetic steel The aqueous surface treatment liquid for electrical steel sheets according to any one of claims 3 to 5. The aqueous surface treatment solution for an electrical steel sheet according to claim 4 , wherein the pH is in the range of 6.5 to 10.0. An insulating film forming step of forming an insulating film by applying and baking the aqueous surface treatment liquid for an electromagnetic steel sheet according to any one of claims 1 to 5 on the electromagnetic steel sheet. A method for producing an electrical steel sheet with an insulating film. Wherein the insulating film forming step, after baking the electrical steel sheet for aqueous surface treatment solution and does not water cooled, or according to claim 6 in which the water cooling time and performing the water cooling such that less than 10 seconds A method for producing an electrical steel sheet with an insulating film. An electrical steel sheet with an insulating film having an insulating film containing an inorganic component including an silicate or an alkali silicate, an organic resin component, and a rust inhibitor,
The electrical steel sheet with an insulating film is one in which seizure and cracking of the insulating film are not recognized even after heating at 700 ° C. for 2 hours, and the interlayer is measured by the interlayer resistance measuring method of JIS C 2550. Resistance is 1 Ω · cm ² / sheet or more,
The rust inhibitor, insulation film having an electromagnetic steel sheet you being a cyclic compound having a mercapto group. An electrical steel sheet with an insulating film having an insulating film containing an inorganic component containing a silicate or an alkali silicate, an organic resin component, and S (sulfur),
The electrical steel sheet with an insulating film is one in which seizure and cracking of the insulating film are not recognized even after heating at 700 ° C. for 2 hours, and the interlayer is measured by the interlayer resistance measuring method of JIS C 2550. Resistance is 1 Ω · cm ² / sheet or more,
The S (sulfur) is, insulation film having an electromagnetic steel sheet you wherein a is derived from cyclic compounds having a mercapto group. The silicate or alkali silicate is lithium silicate, and the cyclic compound having a mercapto group is 2,5-dimercaptothiadiazole or 3,5-dimercapto-1,2,4-triazole. The electrical steel sheet with an insulating film according to claim 8 or claim 9 .

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