Title of Invention	MAGNETIC STEEL SHEET WITH SEMI-ORGANIC INSULATION COATING FILM
Abstract	In a semi-organic insulation coating comprising an inorganic component and an organic resin a Zr compound and an Si compound containing a plate-like silica as an inorganic component are included in a ratio in a dry coating of 20 to 70 mass% of Zr compound (converted to ZrO2) and 10 to 50 mass% of Si compound containing plate-like silica (converted to SiO2) and the remainder is substantially an organic resin whereby there can be provided a magnetic steel sheet with a semi-organic insulation coating having no deterioration of corrosion resistance and water resistance without containing a chromium compound and being excellent in the powdering resistance scratch resistance sticking resistance TIG weldability and punchability but also the coating appearance.

Title of Invention

MAGNETIC STEEL SHEET WITH SEMI-ORGANIC INSULATION COATING FILM

Abstract

In a semi-organic insulation coating comprising an inorganic component and an organic resin a Zr compound and an Si compound containing a plate-like silica as an inorganic component are included in a ratio in a dry coating of 20 to 70 mass% of Zr compound (converted to ZrO2) and 10 to 50 mass% of Si compound containing plate-like silica (converted to SiO2) and the remainder is substantially an organic resin whereby there can be provided a magnetic steel sheet with a semi-organic insulation coating having no deterioration of corrosion resistance and water resistance without containing a chromium compound and being excellent in the powdering resistance scratch resistance sticking resistance TIG weldability and punchability but also the coating appearance.

Full Text	FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & The Patent Rules, 2003 COMPLETE SPECIFICATION 1. TITLE OF THE INVENTION: MAGNETIC STEEL SHEET WITH SEMI-ORGANIC INSULATION COATING 2. APPLICANT: Name: JFE STEEL CORPORATION Nationality: Japan. Address: 2-3, Uchisaiwai-cho 2-chome, Chiyoda-ku, Tokyo 1000011, Japan. 3. PREAMBLE TO THE DESCRIPTION: The following specification particularly describes the invention and the manner in which it is to be performed: 2 SPECIFICATION TECHNICAL FIELD [0001] This invention relates to a magnetic steel sheet with a semi-organic insulation coating which has no deterioration of corrosion resistance and water resistance without containing a chromium compound and is excellent in the powdering resistance, scratch resistance, sticking resistance, TIG weldability and punchability but also the uniformity of coating appearance after annealing. BACKGROUND ART [0002] An insulation coating of a magnetic steel sheet used for motors, transformers and the like is required to have various properties such as not only interlaminar resistance but also convenience in working, storage, stability in use and so on. Since the magnetic steel sheet is used in a variety of applications, it is attempted to develop various insulation coatings depending upon the application. When the magnetic steel sheet is subjected to punching, shearing, bending or the like, magnetic properties are deteriorated due to residual strain, so that stress relief annealing at a temperature of about 700 to 800°C is frequently conducted for solving this problem. In this case, therefore, the insulation coating must be resistant to the stress relief annealing. [0003] The Insulation coatings are roughly classified into three types: (1) an inorganic coating placing great importance on weldability and heat resistance, and being resistant to stress relief annealing; (2) a resin-containing inorganic coating aiming at an establishment of punchability and weldability, and being resistant to stress relief annealing (i.e., semiorganic coating); and (3) an organic coating being unable to be subjected to stress relief annealing in a special application, but the coatings containing an inorganic component as shown in the above items (1) and (2) are resistant to the stress relief annealing as general-purpose product, and they contain a chromium compound. [0004] Particularly, chromate-based insulation coating of type (2) can dramatically improve the punchability in a 1-coat and 1-bake production as compared with the inorganic insulation coating and are widely used. For example, in Patent Document 1 is disclosed a magnetic steel sheet having an electrical insulation coating obtained by applying a treating solution, which is formed by compounding a dichromate-based aqueous solution containing at least one 3 divalent metal with 5-120 parts by weight as a solid content of a resin emulsion having a ratio of vinyl acetate/VeoVA as an organic resin of 90/10 to 40/60 and 10-60 parts by weight of an organic reducing agent based on 100 parts by weight of CrO3 in the aqueous solution, onto a surface of a base iron sheet and then subjecting to baking according to the usual manner. [0005] However, environmental awareness is rising in recent years, and hence products having an insulation coating free of chromium compound are demanded by consumers even in the field of magnetic steel sheets. [0006] There are developed magnetic steel sheets with an insulation coating containing no chromium compound. For example, as an insulation coating containing no chromium but having a good punchability are described ones containing a resin and colloidal silica (alumina-containing silica) in Patent Document 2. Also, an insulation coating comprising one or more of colloidal silica, alumina sol and zirconia sol and containing a water soluble or emulsion resin is described in Patent Document 3, and an insulation coating composed mainly of a phosphate containing no chromium and containing a resin is described in Patent Document 4. [0007] However, these magnetic steel sheets with the insulation coatings containing no chromium have problems that the bond between inorganic substances is relatively weak and the corrosion resistance is poor as compared with those containing a chromium compound. Also, when back tension is applied by rubbing the steel sheet surface with a felt in slit working (by using a tension pad), the occurrence of powdering comes into question. Furthermore, there is a problem that the coating becomes weaker after the stress relief annealing and is easily scratched. [0008] For instance, the above problems can not be solved by simply using one or more of colloidal silica, alumina sol and zirconia sol in the method of Patent Document 3. Also, sufficient investigations are not made with respect to the case of mixing these components in combination and at a specific ratio. Furthermore, in the case of a phosphate coating with a composition containing no chromium as described in Patent Document 4, sticking occurs and the water resistance tends to be deteriorated. These problems are apt to be easily caused in the baking at a relatively low temperature of not higher than 300°C, and the occurrence becomes particularly remarkable at a temperature of not higher than 200°C. Meanwhile, the baking temperature should be as low as possible from a viewpoint of the reduction of energy consumption and production cost, and so on. [0009] In addition, when using the methods described in Patent Documents 5 and 6, i.e. when using a coating comprising a polysiloxane polymer obtained by 4 copolymerizing polysiloxane with various organic resins and an inorganic compound such as silica, silicate or the like , there are problems that blowholes occur in the TIG welding, and that a spotted pattern occurs after annealing depending on the kind of the steel. PRIOR ART DOCUMENTS PATENT DOCUMENT [0010] Patent Document 1: JP-B-S60-36476 Patent Document 2: JP-A-H10-130858 Patent Document 3: JP-A-H10-46350 Patent Document 4: Japanese Patent No. 2944849 Patent Document 5: JP-A-2007-197820 Patent Document 6: JP-A-2007-197824 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION [0011] Therefore, the inventors have made various studies in order to solve the above problems, and found out that the above problems can be advantageously solved by compositely including a Zr compound and an Si compound containing a plate-like silica, or further a B compound as an inorganic component in the semi-organic coating. The invention is based on the above finding. [0012] More specifically, the summary and construction of the invention are as follows. 1. A magnetic steel sheet provided on its surface with a semi-organic insulation coating comprising an inorganic component and an organic resin, characterized in that the inorganic component of the coating comprises a Zr compound and an Si compound containing a plate-like silica as a ratio in a dry coating of 20-70 mass% of Zr compound (converted to ZrO2) and 10-50 mass% of Si compound containing a plate-like silica (converted to SiO2), and the remainder of the coating is the organic resin. [0013] 2. The magnetic steel sheet with a semi-organic insulation coating according to the item 1, wherein the plate-like silica has an average particle size of 10 to 600 nm. [0014] 3. The magnetic steel sheet with a semi-organic insulation coating according to the item 1 or 2, wherein the plate-like silica has an aspect ratio (average length/average thickness ratio) of 2 to 400. [0015] 4. The magnetic steel sheet with a semi-organic insulation coating according to any one of the items 1 to 3, wherein the inorganic component further 5 contains a B compound as a ratio in a dry coating of 0.1-5 mass% of B compound (converted at B2O3 ). [0016] 5. The magnetic steel sheet with a semi-organic insulation coating according to any one of the items 1 to 4, wherein the coating further contains not more than 30 mass% in total of one or more selected from a nitric acid compound (converted to NO3), a silane coupling agent (converted to a solid content) and a phosphorus compound (converted to P2O5) as a ratio in a dry coating. [0017] In other words, the invention is a magnetic steel sheet provided on its surface with a semi-organic insulation coating comprising an inorganic component and an organic resin, wherein as the inorganic component is included (1) a Zr compound and an Si compound containing a plate-like silica as a ratio in a dry coating of 20-70 mass% of Zr compound (converted to ZrO2) and 10-50 mass% of Si compound containing plate-like silica (converted to SiO2); (2) if necessary, a B compound as a ratio in a dry coating of 0.1-5 mass% of B compound (converted to B2O3); and (3) if necessary, not more than 30 mass% in total of one or more selected from a nitric acid compound (converted to NO3), a silane coupling agent (converted to a solid content) and a phosphorus compound (converted to P2O5) as a ratio in a dry coating, the remainder of the coating is substantially the organic resin (i.e., with an allowance of containing impurities and known additives), and moreover, preferably, the average particle size of the plate-like silica is 10 to 600 nm and/or the aspect ratio (average length/average thickness ratio) of the plate-like silica is 2 to 400. EFFECT OF THE INVENTION [0018] According to the invention, there can be provided a magnetic steel sheet with a semi-organic insulation coating which is excellent in various properties such as powdering resistance, scratch resistance, sticking resistance, TIG weldability and punchability, and has no deterioration of water resistance and corrosion resistance without containing a chromium compound, but also is excellent in the uniformity of coating appearance after annealing. BRIEF DESCRIPTION OF THE DRAWING [0019] FIG.1 is photographs showing coating appearance after stress relief annealing in comparison. BEST MODE FOR CARRYING OUT THE INVENTION [0020] The invention will be specifically described below. First, the reasons why the compounding ratio of the Zr compound and Si compound containing plate-like silica, and further B compound as the inorganic 6 component of the semi-organic coating in the invention is limited to the above range will be described. Moreover, it should be noted that mass % of these components is the ratio in a dry coating. [0021] Zr compound: 20 to 70 mass% as converted to ZrO2 The Zr compound has a strong bonding force to oxygen and can be strongly bonded to an oxide, a hydroxide and the like on the Fe surface. Also, since the Zr compound has three or more chemical bonds, a strong coating can be formed by forming a network between mutual Zrs or between Zr and other inorganic compound without using chromium. However, when the ratio of the Zr compound in the dry coating is less than 20 mass% as converted to ZrO2, not only the adhesion property, corrosion resistance and powdering resistance are deteriorated, but also the deterioration of appearance after annealing due to an Si compound occurs. On the other hand, when it exceeds 70 mass%, the corrosion resistance and powdering resistance are deteriorated, and also the scratch resistance on the surface of the sheet after the stress relief annealing is deteriorated. Therefore, the amount of the Zr compound is limited to a range of 20 to 70 mass% as converted to ZrO2. [0022] As such a Zr compound are mentioned, for example, zirconium acetate, zirconium propionate, zirconium oxychloride, zirconium nitrate, zirconium ammonium carbonate, zirconium potassium carbonate, zirconium hydroxychloride, zirconium sulfate, zirconium phosphate, zirconium sodium phosphate, zirconium potassium hexafluoride, tetra-n-propoxy-zirconium, tetra-n-butoxy-zirconium, zirconium tetraacetylacetonate, zirconium tributoxy acetylacetonate, zirconium tributoxy stearate, and so on. They may be used alone or in a combination of two or more. [0023] Si compound containing plate-like silica: 10 to 50 mass% as converted to SiO2 The plate-like silica according to the invention is also called as leaf-like silica or scale-like silica, and has a layered silicate structure formed by laminating many SiO2 thin layers, and is mostly non-crystalline or microcrystalline. Such a plate-like silica is excellent in the inhibitive performance of permeating corrosive substance due to the layered form, excellent in the adhesion property due to the presence of many hydroxyl groups, and excellent in the slidability due to the flexibility as compared with a commonly-used silica particle, for example, colloidal silica or the like. Therefore, it is more effective in the improvement of corrosion resistance and punchability. The plate-like silica can be obtained by preparing agglomerated particles of laminated primary particles of the thin layers, and pulverizing these agglomerated particles. 7 Here, the average particle size of the plate-like silica is preferably about 10 to 600 nm. More preferably, it is within a range of 100 to 450 nm. In addition, the aspect ratio (length/thickness ratio) of the plate-like silica is preferably about 2 to 400. More preferably, it is within a range of 10 to 100. [0024] Moreover, since the plate-like silica tends to be laminated by orienting parallel to the surface of the steel sheet, the length (length in the longitudinal direction) of the plate-like silica can be determined by observing the surface of the coating with SEM (Scanning Electron Microscope). Also, the thickness of the plate-like silica can be determined by observing the cross section of frozen fracture, FIB (focused ion beam) or the like with SEM. Therefore, the length and the thickness of the plate-like silica are measured at several places by SEM observation, and the aspect ratio (average length/average thickness ratio) is determined from an average of these measured values. Moreover, when silica is oval or polygonal, the average particle size in the sheet plane and the average thickness in the cross section are similarly measured at several places by SEM observation, and the aspect ratio is determined by (average particle size) / (average thickness). [0025] As the Si compounds other than the plate-like silica may be mentioned colloidal silica, fumed silica, alkoxysilane, siloxane and the like. They contributes to the improvement of corrosion resistance, and adhesion property after stress relief annealing. Generally, colloidal silica and fumed silica are spherical or an ellipsoidal body with an aspect ratio of less than 2, while alkoxysilane and siloxane are amorphous. When the compounding ratio of the plate-like silica in the whole of the Si compound is less than 50 mass%, good corrosion resistance and punchability as aimed in the invention cannot be obtained, so that the compounding ratio of the plate-like silica is preferable to be not less than 50 mass%. Of course, all of the Si compounds may be plate-like silica. A particularly preferable range is 50 to 100 mass%. Moreover, the compounding ratio of the plate-like silica can be determined, for example, by measuring SiO2 amount (B) in the plate-like silica region and SiO2 amount (A) in the other regions at the FIB cross section and calculating B / (A+B) × 100. Furthermore, the SiO2 amount in each region can be determined from the average Si concentration and the area of the region measured by EDS (Energy Dispersion Spectroscopy) and the like. [0026] The aforementioned Si compound containing the plate-like silica is useful in solving the problems caused when the Zr compound is added alone. More specifically, although the use of the Zr compound alone tends to deteriorate the corrosion resistance and powdering resistance and considerably deteriorate the scratch resistance on a stress 8 relief annealed steel sheet, the powdering resistance and scratch resistance can be largely improved by compounding proper amount of the Si compound. Here, when the amount of the Si compound included in the dry coating is less than 10 mass% as converted to SiO2, sufficient corrosion resistance cannot be obtained, while when it exceeds 50 mass%, the powdering resistance is deteriorated, and also the scratch resistance on the stress relief annealed steel sheet is deteriorated, so that the amount of the Si compound is limited to a range of 10 to 50 mass%. [0027] In the invention, a B compound may be further included as the inorganic component in addition to the aforementioned Zr compound and the Si compound containing the plate-like silica. B compound: 0.1 to 5 mass% as converted to B2O3 The B compound advantageously contributes to solve the problems caused when the Zr compound is added alone. That is, when the Zr compound is added alone, a tendency of deteriorating the corrosion resistance and powdering resistance and considerably deteriorating the scratch resistance on the stress relief annealed steel sheet is seen. The reason is assumed due to the fact that when the Zr compound is used alone, the volume constriction is large in the baking and hence coating cracking easily occurs, and a place of exposing the substrate is partially caused. In contrast, when a proper amount of the B compound is compounded to the Zr compound, the coating cracking caused in the case of using the Zr compound alone can be effectively mitigated to considerably improve the powdering resistance. When the ratio of the B compound in the dry coating is not less than 0.1 mass% as converted to B2O3, the addition effect is exerted, while when it is not more than 5 mass%, unreacted substances do not remain in the coating, and adhesive between the coatings (i.e. a defect of fusing the coatings to each other) after stress relief annealing (sticking) does not occur, so that the amount of the B compound is preferable to be within a range of 0.1 to 5 mass% as converted to B2O3. [0028] As the B compounds are mentioned boric acid, orthoboric acid, metaboric acid, tetraboric acid, sodium metaborate, sodium tetraborate and the like. They may be used alone or in a combination of two or more. However, it is not limited to them, and may include, for example, a compound dissolving in water to generate a boric ion, and also the boric ion may be polymerized in a linear or a cyclic state. [0029] In the invention, in addition to the aforementioned inorganic components, one or more selected from a nitric acid compound, a silane coupling agent and a phosphorous compound described below can be further included in the dry coating at a ratio of not more than 30 mass% in total. Moreover, the ratios of the nitric acid 9 compound, silane coupling agent and phosphorous compound in the dry coating are represented by a value converted to NO3 (nitric acid compound), a value converted to a solid content (silane coupling agent) and a value converted to P2O5 (phosphorous compound), respectively. The nitric acid compound, silane coupling agent and phosphorous compound effectively contribute to the improvement of corrosion resistance. When the ratio in the dry coating is not more than 30 mass% in total, unreacted substances do not remain in the coating and the water resistance is not deteriorated, so that the content is preferable to be not more than 30 mass% in total. In order to sufficiently develop the effect of these components, it is preferable to include these components at a ratio of not less than 1 mass% in the dry coating. [0030] In the invention, nitric acid-based or nitrous acid-based compounds and further hydrates thereof as shown below are advantageously suitable as the nitric acid compound. -Nitric acid-based: nitric acid (HNO3), potassium nitrate (KNO3), sodium nitrate (NaNO3), ammonium nitrate (NH4NO3), calcium nitrate (Ca(NO3)2), silver nitrate (AgNO3), iron (II) nitrate (Fe(NO3)2), iron (III) nitrate (Fe(NO3)3), copper (II) nitrate (Cu(NO3)2), barium nitrate (Ba(NO3)2), aluminum nitrate (Al(NO3)3), magnesium nitrate (Mg(NO3)2), zinc nitrate (Zn(NO3)2), nickel (II) nitrate (Ni(NO3)2), zirconium nitrate (ZrO(NO3)2). -Nitrous acid-based: nitrous acid (HNO2), potassium nitrite, calcium nitrite, silver nitrite, sodium nitrite, barium nitrite, ethyl nitrite, isoamyl nitrite, isobutyl nitrite, isopropyl nitrite, tbutyl nitrite, n-butyl nitrite, n-propyl nitrite. [0031] As the silane coupling agent are advantageously suitable those shown below. -Vinyl-based: vinyl trichlorosilane, vinyl trimethoxysilane, vinyl triethoxysilane. -Epoxy-based: 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropylmethyl diethoxysilane, 3-glycidoxypropyl triethoxysilane. -Styryl-based: p-styryl trimethoxysilane. -Methacryloxy-based: 3-methacryloxy propylmethyl dimethoxysilane, 3-methacryloxy propyl 10 trimethoxysilane, 3-methacryloxy propylmethyl diethoxysilane, 3-methacryloxy propyl triethoxysilane. -Acryloxy-based: 3-acryloxy propyl trimethoxysilane. -Amino-based: N-2-(aminoethyl)-3-aminopropylmethyl dimethoxysilane, N-2- (aminoethyl)-3-aminopropyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3- triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine and a partial hydrolyzate thereof, N-phenyl-3-aminopropyl trimethoxysilane, hydrochloride of N-(vinylbenzyl)-2- aminoethyl-3-aminopropyl trimethoxysilane, special aminosilanes. -Ureido-based: 3-ureidopropyl triethoxysilane. -Chloropropyl-based: 3-chloropropyl trimethoxysilane. -Mercapto-based: 3-mercaptopropylmethyl dimethoxysilane, 3-mercaptopropyl trimethoxysilane. -Polysulfide-based: bis(triethoxysilylpropyl)tetrasulfide. -Isocyanate-based: 3-isocyanatepropyl triethoxysilane. [0032] Furthermore, phosphoric acid and phosphates as shown below are advantageously suitable as the phosphorous compound. -Phosphoric acid: orthophosphoric acid, phosphoric acid anhydride, linear polyphosphoric acid, cyclic metaphosphoric acid. -Phosphate: Magnesium phosphate, aluminum phosphate, calcium phosphate, zinc phosphate. [0033] In the invention, Hf, HfO2, TiO2, Fe2O3 and so on may be incorporated into the inorganic component as an impurity. However, a problem does not particularly occurs when the total amount of these impurities is not more than 1 mass% in the dry coating. [0034] In the invention, it is preferable that the organic resin is compounded at a ratio of 5 to 40 mass% so as to render the content of the inorganic component as 11 mentioned above in the dry coating into 60 to 95 mass%. In the invention, the organic resin is not particularly limited and any of known ones conventionally used are advantageously suitable. The organic resin includes, for example, aqueous resins (emulsion, dispersion, water soluble) of acryl resin, alkyd resin, polyolefin resin, styrene resin, vinyl acetate resin, epoxy resin, phenol resin, polyester resin, urethane resin, melamine resin and so on. Emulsions of acryl resin and ethylene acrylate resin are particularly preferable. [0035] The organic resins effectively contribute to the improvement of the corrosion resistance, scratch resistance and punchability. When the compounding ratio in the dry coating is not less than 5 mass%, the addition effect is large, while when it is not more than 40 mass%, the scratch resistance after stress relief annealing and TIG weldability are not deteriorated, so that the compounding ratio of the organic resin is preferable to be about 5 to 40 mass% as converted to a solid content. [0036] It should be noted that the ratio in the dry coating refers to a ratio of each component in a coating formed on a surface of a steel sheet by applying a treating solution containing the aforementioned components onto the steel sheet, and drying by baking. It can also be determined from residual components (solid content) after drying the treating solution at 180°C for 30 minutes. [0037] Furthermore, the invention does not interrupt the inclusion of additives usually used and other inorganic or organic compounds in addition to the aforementioned components. The additive is added for further enhancing performances and uniformity of the insulation coating, and includes a surfactant, an antirust agent, a lubricant, an antioxidant and the like. Moreover, the amount of the additive compounded in the dry coating is preferable to be not more than about 10 mass% from a viewpoint of the maintaining of sufficient coating properties. [0038] In the invention, the magnetic steel sheet as a starting material is not particularly limited, and any known ones are suitable. That is, any of so-called soft (magnetic) iron sheets (electric iron sheets) having a high magnetic flux density, common cold-rolled steel sheets such as SPPC and the like, non-oriented magnetic steel sheets containing Si and/or Al for increasing specific electrical resistance and so on are advantageously suitable for reducing iron loss. Particularly, it is preferable to use a steel sheet containing about 0.1 to 10 mass% of Si or (Si + Al) and/or a steel sheet having an iron loss W15/50 of not more than about 7 W/kg. [0039] Next, the method for forming the insulation coating will be described. 12 In the invention, a pretreatment of a magnetic steel sheet as a starting material is not particularly defined. More specifically, the steel sheet may be untreated, but it is advantageous to be subjected to a degreasing treatment with alkali or the like and a pickling treatment with hydrochloric acid, sulfuric acid, phosphoric acid or the like. Then, to the surface of this magnetic steel sheet is applied a treating solution formed by compounding a Zr compound and an Si compound containing a plate-like silica, and optionally a B compound and optionally one or more selected from a nitric acid compound, a silane coupling agent and a phosphorous compound, and, if necessary, an additive and the like together with an organic resin at given ratios and then baked to form an insulation coating. As a method for coating the treating solution for insulation coatings are applicable various methods usually and industrially used such as roll coater, flow coater, spray, knife coater and so on. Also, as the baking method are possible a hot air type, an infrared type, an induction heating type and the like as generally conducted. The baking temperature may be a normal level, and may be about 150 to 350°C as a maximum reaching temperature on the steel sheet. [0040] The magnetic steel sheet with an insulation coating according to the invention can remove strain due to punching, for example, by subjecting to stress relief annealing. As a preferable stress relief annealing atmosphere is applied an atmosphere hardly oxidizing iron such as N2 atmosphere, DX gas atmosphere or the like. Here, the corrosion resistance can be further improved by setting a dew point high, for example Dp: about 5 to 60°C to slightly oxidize the surface and cut end surface. Also, the stress relief annealing temperature is preferably 700 to 900°C, more preferably 700 to 800°C. The holding time of the stress relief annealing temperature is preferably longer, and more preferably not shorter than 2 hours. [0041] The amount of the insulation coating adhered is not particularly limited, but is preferably about 0.05 to 5 g/m2 per side. The coating amount or the total solid content mass of the insulation coating according to the invention can be measured from weight reduction after the removal of the coating through dissolving with alkali. If the coating amount is small, it can be determined by using a standard sample having a known coating amount and measuring a relationship between a detection intensity of Zr or Si by a fluorescent X-ray analysis and the coating amount per coating composition and converting the fluorescent X-ray analyzed intensity of Zr or Si into a coating amount depending upon the coating composition based on this calibration curve. When the coating amount is not less than 0.05 g/m2, the insulation property can be satisfied with the corrosion resistance, while when it is not more than 5 g/m2, not only 13 the adhesion property is improved, but also blistering is not caused in the coat baking, and the deterioration of coatability is not incurred. More preferably, it is 0.1 to 3.0 g/m2. Although it is preferable to form insulation coatings on the both sides of the steel sheet, the coating may be formed on only one side depending on the purpose. In addition, the coating is formed on only one side and another insulation coating may be formed on the other side depending on the purpose. EXAMPLES [0042] Although the effect of the invention will be concretely described based on examples below, the invention is not limited to these examples. Example 1 A treating solution is prepared by adding a Zr compound and an Si compound containing a plate-like silica and further a nitric acid compound, a silane coupling agent, a phosphorus compound and an additive to a deionized water together with an organic resin so that components of an insulation coating after drying are shown in Tables 1-1 and 1-2. Moreover, the addition concentration to the deionized water is 50g/l. Each of these treating solutions is applied to a surface of a test piece with a size of 150 mm in width and 300 mm in length cut out from a magnetic steel sheet [A230 (JIS C 2552 (2000))] of 0.5 mm in thickness by means of a roll coater, baked in a hot air baking oven at a baking temperature (temperature arriving in steel sheet) shown in Tables 1-1 and 1-2, and then allowed to cool to room temperature to form insulation coatings on the both sides. [0043] The results examined on the corrosion resistance and powdering resistance of the thus obtained magnetic steel sheets with semi-insulation coatings are shown in Table 2. Further, the scratch resistance after the steel sheets are subjected to stress relief annealing in a nitrogen atmosphere at 750°C for 2 hours, the scratch resistance, sticking resistance, TIG weldability, punchability, water resistance, and appearance after stress relief annealing are examined to obtain results also shown in Table 2. [0044] Moreover, types of the Zr compound are shown in Table 3, types of the Si compound are shown in Table 4, types of the phosphorous compound and nitric acid compound are shown in Table 5, types of the silane coupling agent are shown in Table 6, and types of the organic resin are shown in Table 7. [0045] Also, the evaluation method for each property is as follows. The humidity cabinet test (50°C, relative humidity ≥ 98%) is conducted to 14 the test piece, and a rate of developing red rust after 48 hours is visually observed and evaluated as an area ratio. (Criteria) ☆: red rust area ratio less than 5 % ◎: red rust area ratio not less than 5 % but less than 15 % ○: red rust area ratio not less than 15 % but less than 40 % △: red rust area ratio not less than 40 % but less than 60 % ×: red rust area ratio not less than 60 % [0046] Test conditions; Felt contact face width: 20 mm × 10 mm, load: 0.4 MPa (3.8 kg/cm2), 100 times of simple reciprocation on a coating surface. Scratch marks after the test are visually observed to evaluate an exfoliated state and a powdered state of the coating. (Criteria) ◎: coating residual ratio any scratch mark is hardly observed ○: coating residual ratio slight scratch marks and slight powdering are observed △: coating residual ratio abrasion of the coating progresses, and scratch marks and powdering are clearly observed ×: coating residual ratio reach to expose an iron substrate, and powdering dust is severe [0047] The surface of the sample annealed under test condition of holding in an N2 atmosphere at 750°C for 2 hours is scratched by a steel sheet shear edge to judge the degrees of scratch and powdering. (Criteria) ◎: any occurrence of scratch and powdering is hardly observed ○: slight scratch marks and slight powdering are observed △: scratch marks and powdering are clearly observed ×: reach to expose an iron substrate, and scratch dust is severe [0048] 10 test sample sheets with 50 mm square are stacked and annealed in a nitrogen atmosphere at 750°C for 2 hours while applying a load: 20 kPa (200 g/cm2). Then, 500 g of weight is dropped on the test samples (steel sheets) to measure a drop height when the test sample sheets are divided into five pieces. (Criteria) 15 ◎: not more than 10 cm ○: more than 10 cm but not more than 15 cm △: more than 15 cm but not more than 30 cm ×: more than 30 cm [0049] The test samples are laminated under a pressure of 9.8 MPa (100 kgf/cm2) so as to have a thickness of 30 mm, and an end face portion thereof (length 30 mm) is subjected to TIG welding under the following conditions: -welding current: 120 A -Ar gas flow rate: 6 liter/min -welding speed: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 cm/min (Criteria) Relative merits are judged by the welding speed satisfying the number of blowholes of not more than 5 per bead. ◎: not less than 60 cm/min ○: not less than 40 cm/min but less than 60 cm/min △: not less than 20 cm/min but less than 40 cm/min ×: less than 20 cm/min [0050] The test sample is subjected to punching with a 15 mm steel dice until a burr height reaches to 50 μm, and the evaluation is represented by the number of punchings. (Criteria) ◎: not less than 1,200,000 times ○: not less than 500,000 times but less than 1,200,000 times △: not less than 100,000 times but less than 500,000 times ×: less than 100,000 times [0051] The test sample is exposed in a steam above a boiling water for 30 minutes to observe an appearance change. (Criteria) ◎: no change ○: slight change of color is visually observed △: clear change of color is visually observed ×: coating dissolved [0052] 16 An appearance of a steel sheet is visually observed by holding the test sample in an N2 atmosphere at 750°C for 2 hours and then cooling to room temperature. (Criteria) ◎: appearance after annealing is completely uniform as shown in FIG.1(a) ○: unevenness in appearance after annealing as shown in FIG.1(b) △: spotted pattern in appearance after annealing as shown in FIG.1(c) ×: remarkable spotted pattern in appearance after annealing as shown in FIG.1(d) 17 [0053] Table 1-1 Table1-1 Type in Table 3 Addition amount (converted to ZrO2)(mass%) Type* in Table 4 Addition amount (converted to SiO2)(mass%) Type in Table 5 Addition amount (converted to P2O5%)(mass%) Type in Table 5 Addition amount (converted to NO3)(mass%) Type in Table 6 Addition amount (converted to solid content)(mass%) 1 Z1 60 S2(100) 22 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 1 2 Z1 50 S2(80) 22 - 0 - 0 - 0 R1 28 250 0.3 Invention Example 2 3 Z1 70 S2(100) 12 - 0 - 0 - 0 R1 18 250 0.4 Invention Example 3 4 Z1 55 S2(50) 15 - 0 - 0 - 0 R1 38 250 0.5 Invention Example 4 5 Z1 57 S2(70) 35 - 0 - 0 - 0 R1 8 250 0.5 Invention Example 5 6 Z2 50 S2(80) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 6 7 Z3 50 S2(50) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 7 8 Z4 50 S2(40) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 8 9 Z5 50 S2(30) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 9 10 Z6 50 S2(20) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 10 11 Z1 50 S1(100) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 11 12 Z1 50 S3(80) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 12 13 Z1 50 S4(80) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 13 14 Z1 40 S2(100) 22 P1 30 - 0 - 0 R1 8 250 0.5 Invention Example 14 15 Z1 40 S2(50) 22 P2 30 - 0 - 0 R1 8 250 0.5 Invention Example 15 16 Z1 40 S2(100) 22 - 0 N1 30 - 0 R1 8 250 0.5 Invention Example 16 17 Z1 40 S2(50) 22 - 0 N1 30 - 0 R1 8 250 0.5 Invention Example 17 18 Z1 40 S2(80) 22 - 0 - 0 C11 30 R1 8 250 0.5 Invention Example 18 Inside ( ) shows the ratio (mass%) of plate-like silica in Si compound. The remainder is S0 (colloidal silica). No. Components of insulation coating Baking temperature (C) Coating amount of insulation coating (g/m2) Compounding amount in dry coating (mass%) Remarks Inorganic component Arbitrary addition component Organic resin Zr compound Si compound Phosphorus compound Nitric acid compound Silane coupling agent type in Table 7 18 [0054] Table 1-2 Table1-2 Type in Table 3 Addition amount (converted to ZrO2)(mass%) Type in Table 4 Addition amount (converted to SiO2)(mass%) Type in Table 5 Addition amount (converted to P2O5)(mass%) Type in Table 5 Addition amount (converted to NO3)(mass%) Type in Table 6 Addition amount (converted to solid content)(mass%) 19 Z1 40 S2(80) 22 - 0 - 0 C12 30 R1 8 250 0.5 Invention Example 19 20 Z1 40 S2(80) 22 - 0 - 0 C13 30 R1 8 250 0.5 Invention Example 20 21 Z1 50 S2(100) 32 - 0 - 0 - 0 R1 18 250 0.03 Invention Example 21 22 Z1 50 S2(100) 32 - 0 - 0 - 0 R1 18 250 5 Invention Example 22 23 Z1 50 S2(80) 32 - 0 - 0 - 0 R2 18 250 0.5 Invention Example 23 24 Z1 50 S2(80) 32 - 0 - 0 - 0 R3 18 250 0.5 Invention Example 24 25 Z1 50 S2(80) 32 - 0 - 0 - 0 R4 18 250 0.5 Invention Example 25 26 Z1 10 S2(80) 32 - 0 - 0 - 0 R1 58 250 0.3 Comparative Example 1 27 Z1 80 S2(80) 12 - 0 - 0 - 0 R1 8 250 0.4 Comparative Example 2 28 Z1 50 S2(80) 5 - 0 - 0 - 0 R1 45 250 0.5 Comparative Example 3 29 Z1 32 S2(80) 60 - 0 - 0 - 0 R1 8 250 0.5 Comparative Example 4 30 Z1 30 S2(100) 12 P1 50 - 0 - 0 R1 8 250 0.5 Comparative Example 5 31 Z1 30 S2(50) 12 P2 50 - 0 - 0 R1 8 250 0.5 Comparative Example 6 32 Z1 30 S2(100) 12 - 0 N1 50 - 0 R1 8 250 0.5 Comparative Example 7 33 Z1 30 S2(50) 12 - 0 N2 50 - 0 R1 8 250 0.5 Comparative Example 8 34 Z1 30 S2(100) 12 - 0 - 0 C11 50 R1 8 250 0.5 Comparative Example 9 35 Z1 30 S2(100) 12 - 0 - 0 C12 50 R1 8 250 0.5 Comparative Example 10 36 Z1 30 S2(100) 12 - 0 - 0 C13 50 R1 8 250 0.5 Comparative Example 11 37 Z1 50 only SO 42 - 0 - 0 - 0 R1 8 250 0.5 Comparative Example 12 Inside ( ) shows a ratio (mass%) of plate-like silica in Si compound. The remainder is S0 (colloidal silica). No. Components of insulation coating Baking temperatur e (C) Coating amount of insulation coating (g/m2) Compounding amount in dry coating (mass%) Remarks Inorganic components Arbitrary addition components Organic resin Zr compound Si compound Phosphorus compound Nitric acid compound Silane coupling agent Type in Table 7 19 [0055] Table 2 Table 2 Corrosion resistance Powdering resistance Scratch resistance after annealing Sticking resistance TIG weldability Punchability Water resistance Appearance after annealing 1 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 1 2 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 2 3 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 3 4 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 4 5 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 5 6 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 6 7 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 7 8 ◯ ◯ ◎ ◎ ◎ ◯ ◎ ◎ Invention Example 8 9 ◯ ◯ ◎ ◎ ◎ ◯ ◎ ◎ Invention Example 9 10 ◯ ◯ ◎ ◎ ◎ ◯ ◎ ◎ Invention Example 10 11 ◯ ◯ ◎ ◎ ◎ ◯ ◎ ◎ Invention Example 11 12 ◯ ◯ ◎ ◎ ◎ ◯ ◎ ◎ Invention Example 12 13 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 13 14 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 14 15 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 15 16 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 16 17 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 17 18 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 18 19 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 19 20 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 20 21 ◯ ◯ ◯ ◎ ◎ ◯ ◯ ◎ Invention Example 21 22 ◎ ◯ ◯ ◎ ◯ ◎ ◎ ◯ Invention Example 22 23 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 23 24 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 24 25 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 25 26 × × × ◎ × ◎ ◎ × Comparative Example 1 27 × × × ◎ ◎ ◎ ◎ ◎ Comparative Example 2 28 △ △ △ ◎ △ ◎ ◎ ◎ Comparative Example 3 29 △ × × ◎ ◎ △ ◎ ◎ Comparative Example 4 30 △ △ △ ◎ ◎ ◎ △ ◎ Comparative Example 5 31 △ △ △ ◎ ◎ △ × △ Comparative Example 6 32 △ △ △ ◎ ◎ ◎ × ◎ Comparative Example 7 33 △ △ △ ◎ ◎ △ × △ Comparative Example 8 34 △ △ △ ◎ ◎ ◎ × ◎ Comparative Example 9 35 △ △ △ ◎ ◎ ◎ × ◎ Comparative Example 10 36 △ △ △ ◎ ◎ ◎ × ◎ Comparative Example 11 37 × △ △ ◯ ◎ × × × Comparative Example 12 No. Coating properties Remarks 20 [0056] Table 3 Symbol Name Chemical formula Manufacturer Trade name Z1 Ammonium zirconium carbonate (NH4)2[Zr(CO3)2(OH2)] Daiichi Kigenso Kagaku Co., Ltd. Zircosol AC-20 Z2 Potassium zirconium carbonate K2[Zr(CO3)2(OH2)] Nippon Light Metal Co., Ltd. Zirmel 1000 Z3 Zirconium acetate (CH3CO2)nZr Daiichi Kigenso Kagaku Co., Ltd. Zircosol ZA-20 Z4 Zirconium sulfate H2Zr(OH)2(SO4)2 Nippon Light Metal Co., Ltd. - Z5 Zirconium nitrate ZrO(NO3)2 Nippon Light Metal Co., Ltd. - Z6 Potassium zirconium hexafluoride K2ZrF6 Mitsubishi Materials Electronic Chemicals Co., Ltd. - [0057] Table 4 Symbol Content S0 Colloidal silica with average particle size: 13 nm S1 Plate-like silica with average particle size: 50 nm, aspect ratio: 2 S2 Plate-like silica with average particle size: 200 nm, aspect ratio: 10 S3 Plate-like silica with average particle size: 600 nm, aspect ratio: 400 S4 Plate-like silica with average particle size: 300 nm, aspect ratio: 20 21 [0058] Table 5 Symbol Name Chemical formula P1 Orthophosphoric acid H3PO4 P2 Ammonium phosphate (NH4)3PO4 N1 Nickel nitrate Ni(NO3)2∙6H2O N2 Zirconium nitrate ZrO(NO3)2 [0059] Table 6 Symbol Name CI1 Vinyltrimethoxysilane CI2 3-glycidoxypropyltrimethoxysilane CI3 N-2-(aminoethyl)-3- aminopropylmethyldimethoxysilane [0060] Table 7 Symbol Name Manufacturer Trade name R1 Epoxy resin ADEKA Corporation ADEKA RESIN EM R2 Polyester resin TOYOBO Co., Ltd. Vylonal MD1200 R3 Acryl resin DIC Corporation VONCOAT CP6140 R4 Urethane resin ADEKA Corporation ADEKA BONTIGHTER HUX [0061] As shown in Table 2, all of the magnetic steel sheets with a semi-organic insulation coating obtained according to the invention are excellent in not only the corrosion resistance and powdering resistance but also the scratch resistance after stress relief annealing, sticking resistance, TIG weldability, punchability and water resistance, and further excellent in the appearance after stress relief annealing. On the other hand, Comparative Examples 1 and 2, wherein the amount of Zr compound is out of the adequate range, are particularly poor in the corrosion resistance, powdering resistance and scratch resistance after annealing. Comparative Example 1 is also poor in the TIG weldability and appearance after annealing. 22 Also, Comparative Example 3, wherein the amount of Si compound is less than the lower limit, is poor in the corrosion resistance, powdering resistance, scratch resistance after annealing and TIG weldability, while Comparative Example 4, wherein the amount of Si compound is more than the upper limit, is particularly poor in the powdering resistance and scratch resistance after annealing. Furthermore, all of Comparative Examples 5 to 11 containing an amount of nitric acid compound or silane coupling agent or phosphorous compound exceeding over the adequate range are poor in the corrosion resistance, powdering resistance, scratch resistance after annealing and water resistance. Moreover, Comparative Example 12 using only colloidal silica without plate-like silica as an Si compound is particularly poor in the corrosion resistance, punchability, water resistance and appearance after annealing, and is also not as good as Inventive Examples in the powdering resistance and scratch resistance after annealing. [0062] Example 2 A treating solution is prepared by adding a Zr compound, a B compound and a Si compound containing a plate-like silica, and further a nitric acid compound, a silane coupling agent, a phosphorous compound or an additive to a deionized water together with an organic resin so that components of an insulation coating after drying are shown in Tables 8-1 and 8-2. Moreover, the addition concentration to the deionized water is 50g/l. Each of these treating solutions is applied onto surfaces of a test piece with a size of 150 mm in width and 300 mm in length, which is cut out from a magnetic steel sheet [A230 (JIS C 2552 (2000))] of 0.5 mm in thickness, by means of a roll coater, baked in a hot air baking oven at a baking temperature (maximum reaching temperature on steel sheet) shown in Tables 8-1 and 8-2, and then allowed to cool to room temperature to form insulation coatings on the both sides. [0063] The results examined on the corrosion resistance and powdering resistance of the thus obtained magnetic steel sheet with semi-insulation coatings are shown in Table 9. Further, the scratch resistance the steel sheets are subjected to stress relief annealing in a nitrogen atmosphere at 750°C for 2 hours, the scratch resistance, sticking resistance, TIG weldability, punchability, water resistance, and appearance after stress relief annealing are examined to obtain results also shown in Table 9. Moreover, the type of the B compound is shown in Table 10. Also, the evaluation method for each property is the same as Example 1. 23 [0064] Table 8-1 Table 8-1 Type in Table 3 Addition amount (converted to ZrO2)(mass%) Type in Table 10 Addition amount (converted to B2O3)(mass%) Type in Table 4 Addition amount (converted to SiO2)(mass%) Type in Table 5 Addition amount (converted to P2O5%)(mass%) Type in Table 5 Addition amount (converted to NO3)(mass%) Type in Table 6 Addition amount (converted to solid content)(mass%) 1 Z1 50 B1 2 S2(100) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 1 2 Z1 20 B1 2 S2(80) 50 - 0 - 0 - 0 R1 28 250 0.3 Invention Example 2 3 Z1 70 B1 2 S2(100) 10 - 0 - 0 - 0 R1 18 250 0.4 Invention Example 3 4 Z1 50 B1 0.1 S2(50) 30 - 0 - 0 - 0 R1 19.9 250 0.6 Invention Example 4 5 Z1 50 B1 5 S2(70) 30 - 0 - 0 - 0 R1 15 250 0.2 Invention Example 5 6 Z1 50 B1 2 S2(80) 10 - 0 - 0 - 0 R1 38 250 0.5 Invention Example 6 7 Z1 40 B1 2 S2(50) 48 - 0 - 0 - 0 R1 10 250 0.5 Invention Example 7 8 Z2 50 B1 2 S2(40) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 8 9 Z3 50 B1 2 S2(30) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 9 10 Z4 50 B1 2 S2(20) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 10 11 Z5 50 B1 2 S2(100) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 11 12 Z6 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 12 13 Z1 50 B1 2 S1(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 13 14 Z1 50 B1 2 S3(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 14 15 Z1 50 B1 2 S4(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 15 16 Z1 40 B1 2 S2(100) 18 P1 30 - 0 - 0 R1 10 250 0.5 Invention Example 16 17 Z1 40 B1 2 S2(50) 18 P2 30 - 0 - 0 R1 10 250 0.5 Invention Example 17 18 Z1 40 B1 2 S2(100) 18 - 0 N1 30 - 0 R1 10 250 0.5 Invention Example 18 19 Z1 40 B1 2 S2(50) 18 - 0 N2 30 - 0 R1 10 250 0.5 Invention Example 19 20 Z1 40 B1 2 S2(80) 18 - 0 - 0 C11 30 R1 10 250 0.5 Invention Example 20 Inside ( ) shows the ratio (mass%) of plate-like silica in Si compound. The remainder is S0 (colloidal silica). No. Components of insulation coating Baking temperature (C) Coating amount of insulation coating (g/m2) type in Table 7 Compounding amount in dry coating (mass%) Remarks Inorganic component Arbitrary addition component Organic resin Zr compound B compound Si compound Phosphorus compound Nitric acid compound Silane coupling agent 24 [0065] Table 8-2 Table 8-2 Type in Table 3 Addition amount (converted to ZrO2)(mass%) Type in Table 10 Addition amount (converted to B2O3)(mass%) Type in Table 4 Addition amount (converted to SiO2)(mass%) Type in Table 5 Addition amount (converted to P2O5%)(mass%) Type in Table 5 Addition amount (converted to NO3)(mass%) Type in Table 6 Addition amount (converted to solid content)(mass%) 21 Z1 38 B1 2 S2(80) 20 - 0 - 0 C12 30 R1 10 250 0.5 Invention Example 21 22 Z1 38 B1 2 S2(80) 20 - 0 - 0 C13 30 R1 10 250 0.5 Invention Example 22 23 Z1 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 0.03 Invention Example 23 24 Z1 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 5 Invention Example 24 25 Z1 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 25 26 Z1 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 26 27 Z1 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention Example 27 28 Z1 10 B1 2 S2(80) 30 - 0 - 0 - 0 R1 58 250 0.3 Comparative Example 1 29 Z1 78 B1 2 S2(80) 10 - 0 - 0 - 0 R1 10 250 0.4 Comparative Example 2 30 Z1 50 B1 10 S2(100) 30 - 0 - 0 - 0 R1 10 250 0.2 Comparative Example 3 31 Z1 50 B1 2 S2(80) 3 - 0 - 0 - 0 R1 45 250 0.5 Comparative Example 4 32 Z1 28 B1 2 S2(80) 60 - 0 - 0 - 0 R1 10 250 0.5 Comparative Example 5 33 Z1 28 B1 2 S2(100) 10 P1 50 - 0 - 0 R1 10 250 0.5 Comparative Example 6 34 Z1 28 B1 2 S2(50) 10 P2 50 - 0 - 0 R1 10 250 0.5 Comparative Example 7 35 Z1 28 B1 2 S2(100) 10 - 0 N1 50 - 0 R1 10 250 0.5 Comparative Example 8 36 Z1 28 B1 2 S2(50) 10 - 0 N1 50 - 0 R1 10 250 0.5 Comparative Example 9 37 Z1 28 B1 2 S2(80) 10 - 0 - 0 C11 50 R1 10 250 0.5 Comparative Example 10 38 Z1 28 B1 2 S2(80) 10 - 0 - 0 C12 50 R1 10 250 0.5 Comparative Example 11 39 Z1 28 B1 2 S2(80) 10 - 0 - 0 C13 50 R1 10 250 0,5 Comparative Example 12 40 Z1 30 B1 10 only SO 50 - 0 - 0 - 0 R1 10 250 0.5 Comparative Example 13 *Inside ( ) shows the ratio (mass%) of plate-like silica in Si compound. The remainder is S0 (colloidal silica). No. Components of insulation coating Baking temperature (C) Coating amount of insulation coating (g/m2) type in Table 7 Compounding amount in dry coating (mass%) Remarks Inorganic component Arbitrary addition component Organic resin Zr compound B compound Si compound Phosphorus compound Nitric acid compound Silane coupling agent 25 [0066] Table 9 Table 9 Corrosion resistance Powdering resistance Scratch resistance after annealing Sticking resistance TIG weldability Punchability Water resistance Appearance after annealing 26 [0067] Table 10 Symbol Name Chemical formula B1 Boric acid H3BO3 [0068] As shown in Table 9, all of the magnetic steel sheets with a semi-organic insulation coating obtained according to the invention are excellent in not only the corrosion resistance and powdering resistance but also the scratch resistance after stress relief annealing, sticking resistance, TIG weldability, punchability and water resistance, and further excellent in the appearance after stress relief annealing. On the other hand, Comparative Examples 1 and 2, wherein the amount of Zr compound is out of the adequate range, are particularly poor in the corrosion resistance, powdering resistance and scratch resistance after annealing. Comparative Example 1 is also poor in the TIG weldability and appearance after annealing. Also, Comparative Example 3, wherein the amount of B compound is more than the upper limit, is particularly poor in the sticking resistance. Comparative Example 4, wherein the amount of Si compound is less than the lower limit, is poor in the corrosion resistance and TIG weldability, while Comparative Example 5, wherein the amount of Si compound is more than the upper limit, is particularly poor in the powdering resistance and scratch resistance after annealing. Furthermore, all of Comparative Examples 6 to 12 containing an amount of nitric acid compound or silane coupling agent or phosphorous compound exceeding over the adequate range are poor in the corrosion resistance and water resistance. Moreover, Comparative Example 13 using only colloidal silica without plate-like silica as an Si compound is particularly poor in the corrosion resistance, water resistance and appearance after annealing, and is also not as good as Inventive Examples in the powdering resistance, scratch resistance after annealing, sticking resistance and punchability. 27 We claim: 1. A magnetic steel sheet provided on its surface with a semi-organic insulation coating comprising an inorganic component and an organic resin, characterized in that the inorganic component of the coating comprises a Zr compound and an Si compound containing a plate-like silica as a ratio in a dry coating of 20-70 mass% of Zr compound (converted to ZrO2) and 10-50 mass% of Si compound containing a plate-like silica (converted to SiO2), and the remainder of the coating is the organic resin. 2. The magnetic steel sheet with a semi-organic insulation coating according to claim 1, wherein the plate-like silica has an average particle size of 10 to 600 nm. 3. The magnetic steel sheet with a semi-organic insulation coating according to claim 1 or 2, wherein the plate-like silica has an aspect ratio (average length/average thickness ratio) of 2 to 400. 4. The magnetic steel sheet with a semi-organic insulation coating according to any one of claims 1 to 3, wherein the inorganic component further contains a B compound as a ratio in a dry coating of 0.1-5 mass% of B compound (converted at B2O3 ). 5. The magnetic steel sheet with a semi-organic insulation coating according to any one of claims 1 to 4, wherein the coating further contains not more than 30 mass% in total of one or more selected from a nitric acid compound (converted to NO3), a silane coupling agent (converted to a solid content) and a phosphorus compound (converted to P2O5) as a ratio in a dry coating.

Full Text

FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
& The Patent Rules, 2003
COMPLETE SPECIFICATION

1. TITLE OF THE INVENTION:
MAGNETIC STEEL SHEET WITH SEMI-ORGANIC INSULATION COATING
2. APPLICANT:
Name: JFE STEEL CORPORATION
Nationality: Japan.
Address: 2-3, Uchisaiwai-cho 2-chome, Chiyoda-ku, Tokyo 1000011, Japan.

3. PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in
which it is to be performed:
2

SPECIFICATION

TECHNICAL FIELD
[0001] This invention relates to a magnetic steel sheet with a semi-organic
insulation coating which has no deterioration of corrosion resistance and water
resistance without containing a chromium compound and is excellent in the powdering
resistance, scratch resistance, sticking resistance, TIG weldability and punchability but
also the uniformity of coating appearance after annealing.

BACKGROUND ART
[0002] An insulation coating of a magnetic steel sheet used for motors,
transformers and the like is required to have various properties such as not only
interlaminar resistance but also convenience in working, storage, stability in use and so
on. Since the magnetic steel sheet is used in a variety of applications, it is attempted to
develop various insulation coatings depending upon the application. When the
magnetic steel sheet is subjected to punching, shearing, bending or the like, magnetic
properties are deteriorated due to residual strain, so that stress relief annealing at a
temperature of about 700 to 800°C is frequently conducted for solving this problem.
In this case, therefore, the insulation coating must be resistant to the stress relief
annealing.
[0003] The Insulation coatings are roughly classified into three types:
(1) an inorganic coating placing great importance on weldability and heat
resistance, and being resistant to stress relief annealing;
(2) a resin-containing inorganic coating aiming at an establishment of
punchability and weldability, and being resistant to stress relief annealing (i.e., semiorganic
coating); and
(3) an organic coating being unable to be subjected to stress relief
annealing in a special application, but the coatings containing an inorganic component
as shown in the above items (1) and (2) are resistant to the stress relief annealing as
general-purpose product, and they contain a chromium compound.
[0004] Particularly, chromate-based insulation coating of type (2) can dramatically
improve the punchability in a 1-coat and 1-bake production as compared with the
inorganic insulation coating and are widely used.
For example, in Patent Document 1 is disclosed a magnetic steel sheet
having an electrical insulation coating obtained by applying a treating solution, which is
formed by compounding a dichromate-based aqueous solution containing at least one
3
divalent metal with 5-120 parts by weight as a solid content of a resin emulsion having
a ratio of vinyl acetate/VeoVA as an organic resin of 90/10 to 40/60 and 10-60 parts by
weight of an organic reducing agent based on 100 parts by weight of CrO3 in the
aqueous solution, onto a surface of a base iron sheet and then subjecting to baking
according to the usual manner.
[0005] However, environmental awareness is rising in recent years, and hence
products having an insulation coating free of chromium compound are demanded by
consumers even in the field of magnetic steel sheets.
[0006] There are developed magnetic steel sheets with an insulation coating
containing no chromium compound. For example, as an insulation coating containing
no chromium but having a good punchability are described ones containing a resin and
colloidal silica (alumina-containing silica) in Patent Document 2. Also, an insulation
coating comprising one or more of colloidal silica, alumina sol and zirconia sol and
containing a water soluble or emulsion resin is described in Patent Document 3, and an
insulation coating composed mainly of a phosphate containing no chromium and
containing a resin is described in Patent Document 4.
[0007] However, these magnetic steel sheets with the insulation coatings containing
no chromium have problems that the bond between inorganic substances is relatively
weak and the corrosion resistance is poor as compared with those containing a
chromium compound. Also, when back tension is applied by rubbing the steel sheet
surface with a felt in slit working (by using a tension pad), the occurrence of powdering
comes into question. Furthermore, there is a problem that the coating becomes weaker
after the stress relief annealing and is easily scratched.
[0008] For instance, the above problems can not be solved by simply using one or
more of colloidal silica, alumina sol and zirconia sol in the method of Patent Document
3. Also, sufficient investigations are not made with respect to the case of mixing these
components in combination and at a specific ratio. Furthermore, in the case of a
phosphate coating with a composition containing no chromium as described in Patent
Document 4, sticking occurs and the water resistance tends to be deteriorated.
These problems are apt to be easily caused in the baking at a relatively low
temperature of not higher than 300°C, and the occurrence becomes particularly
remarkable at a temperature of not higher than 200°C. Meanwhile, the baking
temperature should be as low as possible from a viewpoint of the reduction of energy
consumption and production cost, and so on.
[0009] In addition, when using the methods described in Patent Documents 5 and 6,
i.e. when using a coating comprising a polysiloxane polymer obtained by
4
copolymerizing polysiloxane with various organic resins and an inorganic compound
such as silica, silicate or the like , there are problems that blowholes occur in the TIG
welding, and that a spotted pattern occurs after annealing depending on the kind of the
steel.
PRIOR ART DOCUMENTS
PATENT DOCUMENT
[0010] Patent Document 1: JP-B-S60-36476
Patent Document 2: JP-A-H10-130858
Patent Document 3: JP-A-H10-46350
Patent Document 4: Japanese Patent No. 2944849
Patent Document 5: JP-A-2007-197820
Patent Document 6: JP-A-2007-197824
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0011] Therefore, the inventors have made various studies in order to solve the
above problems, and found out that the above problems can be advantageously solved
by compositely including a Zr compound and an Si compound containing a plate-like
silica, or further a B compound as an inorganic component in the semi-organic coating.
The invention is based on the above finding.
[0012] More specifically, the summary and construction of the invention are as
follows.
1. A magnetic steel sheet provided on its surface with a semi-organic
insulation coating comprising an inorganic component and an organic resin,
characterized in that the inorganic component of the coating comprises a Zr compound
and an Si compound containing a plate-like silica as a ratio in a dry coating of 20-70
mass% of Zr compound (converted to ZrO2) and 10-50 mass% of Si compound
containing a plate-like silica (converted to SiO2), and the remainder of the coating is the
organic resin.
[0013] 2. The magnetic steel sheet with a semi-organic insulation coating
according to the item 1, wherein the plate-like silica has an average particle size of 10 to
600 nm.
[0014] 3. The magnetic steel sheet with a semi-organic insulation coating
according to the item 1 or 2, wherein the plate-like silica has an aspect ratio (average
length/average thickness ratio) of 2 to 400.
[0015] 4. The magnetic steel sheet with a semi-organic insulation coating
according to any one of the items 1 to 3, wherein the inorganic component further
5
contains a B compound as a ratio in a dry coating of 0.1-5 mass% of B compound
(converted at B2O3 ).
[0016] 5. The magnetic steel sheet with a semi-organic insulation coating
according to any one of the items 1 to 4, wherein the coating further contains not more
than 30 mass% in total of one or more selected from a nitric acid compound (converted
to NO3), a silane coupling agent (converted to a solid content) and a phosphorus
compound (converted to P2O5) as a ratio in a dry coating.
[0017] In other words, the invention is a magnetic steel sheet provided on its
surface with a semi-organic insulation coating comprising an inorganic component and
an organic resin, wherein as the inorganic component is included
(1) a Zr compound and an Si compound containing a plate-like silica as a ratio in a
dry coating of 20-70 mass% of Zr compound (converted to ZrO2) and 10-50 mass% of
Si compound containing plate-like silica (converted to SiO2);
(2) if necessary, a B compound as a ratio in a dry coating of 0.1-5 mass% of B
compound (converted to B2O3); and
(3) if necessary, not more than 30 mass% in total of one or more selected from a nitric
acid compound (converted to NO3), a silane coupling agent (converted to a solid
content) and a phosphorus compound (converted to P2O5) as a ratio in a dry coating,
the remainder of the coating is substantially the organic resin (i.e., with an allowance of
containing impurities and known additives), and moreover, preferably,
the average particle size of the plate-like silica is 10 to 600 nm and/or the aspect ratio
(average length/average thickness ratio) of the plate-like silica is 2 to 400.
EFFECT OF THE INVENTION
[0018] According to the invention, there can be provided a magnetic steel sheet
with a semi-organic insulation coating which is excellent in various properties such as
powdering resistance, scratch resistance, sticking resistance, TIG weldability and
punchability, and has no deterioration of water resistance and corrosion resistance
without containing a chromium compound, but also is excellent in the uniformity of
coating appearance after annealing.
BRIEF DESCRIPTION OF THE DRAWING
[0019] FIG.1 is photographs showing coating appearance after stress relief
annealing in comparison.
BEST MODE FOR CARRYING OUT THE INVENTION
[0020] The invention will be specifically described below.
First, the reasons why the compounding ratio of the Zr compound and Si
compound containing plate-like silica, and further B compound as the inorganic
6
component of the semi-organic coating in the invention is limited to the above range
will be described. Moreover, it should be noted that mass % of these components is
the ratio in a dry coating.
[0021] Zr compound: 20 to 70 mass% as converted to ZrO2
The Zr compound has a strong bonding force to oxygen and can be strongly
bonded to an oxide, a hydroxide and the like on the Fe surface. Also, since the Zr
compound has three or more chemical bonds, a strong coating can be formed by
forming a network between mutual Zrs or between Zr and other inorganic compound
without using chromium. However, when the ratio of the Zr compound in the dry
coating is less than 20 mass% as converted to ZrO2, not only the adhesion property,
corrosion resistance and powdering resistance are deteriorated, but also the deterioration
of appearance after annealing due to an Si compound occurs. On the other hand, when
it exceeds 70 mass%, the corrosion resistance and powdering resistance are deteriorated,
and also the scratch resistance on the surface of the sheet after the stress relief annealing
is deteriorated. Therefore, the amount of the Zr compound is limited to a range of 20
to 70 mass% as converted to ZrO2.
[0022] As such a Zr compound are mentioned, for example, zirconium acetate,
zirconium propionate, zirconium oxychloride, zirconium nitrate, zirconium ammonium
carbonate, zirconium potassium carbonate, zirconium hydroxychloride, zirconium
sulfate, zirconium phosphate, zirconium sodium phosphate, zirconium potassium
hexafluoride, tetra-n-propoxy-zirconium, tetra-n-butoxy-zirconium, zirconium tetraacetylacetonate,
zirconium tributoxy acetylacetonate, zirconium tributoxy stearate, and
so on. They may be used alone or in a combination of two or more.
[0023] Si compound containing plate-like silica: 10 to 50 mass% as converted to
SiO2
The plate-like silica according to the invention is also called as leaf-like
silica or scale-like silica, and has a layered silicate structure formed by laminating many
SiO2 thin layers, and is mostly non-crystalline or microcrystalline. Such a plate-like
silica is excellent in the inhibitive performance of permeating corrosive substance due
to the layered form, excellent in the adhesion property due to the presence of many
hydroxyl groups, and excellent in the slidability due to the flexibility as compared with
a commonly-used silica particle, for example, colloidal silica or the like. Therefore, it
is more effective in the improvement of corrosion resistance and punchability.
The plate-like silica can be obtained by preparing agglomerated particles of
laminated primary particles of the thin layers, and pulverizing these agglomerated
particles.
7
Here, the average particle size of the plate-like silica is preferably about 10
to 600 nm. More preferably, it is within a range of 100 to 450 nm. In addition, the
aspect ratio (length/thickness ratio) of the plate-like silica is preferably about 2 to 400.
More preferably, it is within a range of 10 to 100.
[0024] Moreover, since the plate-like silica tends to be laminated by orienting
parallel to the surface of the steel sheet, the length (length in the longitudinal direction)
of the plate-like silica can be determined by observing the surface of the coating with
SEM (Scanning Electron Microscope). Also, the thickness of the plate-like silica can
be determined by observing the cross section of frozen fracture, FIB (focused ion beam)
or the like with SEM. Therefore, the length and the thickness of the plate-like silica
are measured at several places by SEM observation, and the aspect ratio (average
length/average thickness ratio) is determined from an average of these measured values.
Moreover, when silica is oval or polygonal, the average particle size in the
sheet plane and the average thickness in the cross section are similarly measured at
several places by SEM observation, and the aspect ratio is determined by (average
particle size) / (average thickness).
[0025] As the Si compounds other than the plate-like silica may be mentioned
colloidal silica, fumed silica, alkoxysilane, siloxane and the like. They contributes to
the improvement of corrosion resistance, and adhesion property after stress relief
annealing. Generally, colloidal silica and fumed silica are spherical or an ellipsoidal
body with an aspect ratio of less than 2, while alkoxysilane and siloxane are amorphous.
When the compounding ratio of the plate-like silica in the whole of the Si
compound is less than 50 mass%, good corrosion resistance and punchability as aimed
in the invention cannot be obtained, so that the compounding ratio of the plate-like
silica is preferable to be not less than 50 mass%. Of course, all of the Si compounds
may be plate-like silica. A particularly preferable range is 50 to 100 mass%.
Moreover, the compounding ratio of the plate-like silica can be determined,
for example, by measuring SiO2 amount (B) in the plate-like silica region and SiO2
amount (A) in the other regions at the FIB cross section and calculating B / (A+B) ×
100. Furthermore, the SiO2 amount in each region can be determined from the average
Si concentration and the area of the region measured by EDS (Energy Dispersion
Spectroscopy) and the like.
[0026] The aforementioned Si compound containing the plate-like silica is useful in
solving the problems caused when the Zr compound is added alone. More specifically,
although the use of the Zr compound alone tends to deteriorate the corrosion resistance
and powdering resistance and considerably deteriorate the scratch resistance on a stress
8
relief annealed steel sheet, the powdering resistance and scratch resistance can be
largely improved by compounding proper amount of the Si compound.
Here, when the amount of the Si compound included in the dry coating is
less than 10 mass% as converted to SiO2, sufficient corrosion resistance cannot be
obtained, while when it exceeds 50 mass%, the powdering resistance is deteriorated,
and also the scratch resistance on the stress relief annealed steel sheet is deteriorated, so
that the amount of the Si compound is limited to a range of 10 to 50 mass%.
[0027] In the invention, a B compound may be further included as the inorganic
component in addition to the aforementioned Zr compound and the Si compound
containing the plate-like silica.
B compound: 0.1 to 5 mass% as converted to B2O3
The B compound advantageously contributes to solve the problems caused
when the Zr compound is added alone. That is, when the Zr compound is added alone,
a tendency of deteriorating the corrosion resistance and powdering resistance and
considerably deteriorating the scratch resistance on the stress relief annealed steel sheet
is seen. The reason is assumed due to the fact that when the Zr compound is used
alone, the volume constriction is large in the baking and hence coating cracking easily
occurs, and a place of exposing the substrate is partially caused.
In contrast, when a proper amount of the B compound is compounded to the
Zr compound, the coating cracking caused in the case of using the Zr compound alone
can be effectively mitigated to considerably improve the powdering resistance.
When the ratio of the B compound in the dry coating is not less than 0.1
mass% as converted to B2O3, the addition effect is exerted, while when it is not more
than 5 mass%, unreacted substances do not remain in the coating, and adhesive between
the coatings (i.e. a defect of fusing the coatings to each other) after stress relief
annealing (sticking) does not occur, so that the amount of the B compound is preferable
to be within a range of 0.1 to 5 mass% as converted to B2O3.
[0028] As the B compounds are mentioned boric acid, orthoboric acid, metaboric
acid, tetraboric acid, sodium metaborate, sodium tetraborate and the like. They may be
used alone or in a combination of two or more. However, it is not limited to them, and
may include, for example, a compound dissolving in water to generate a boric ion, and
also the boric ion may be polymerized in a linear or a cyclic state.
[0029] In the invention, in addition to the aforementioned inorganic components,
one or more selected from a nitric acid compound, a silane coupling agent and a
phosphorous compound described below can be further included in the dry coating at a
ratio of not more than 30 mass% in total. Moreover, the ratios of the nitric acid
9
compound, silane coupling agent and phosphorous compound in the dry coating are
represented by a value converted to NO3 (nitric acid compound), a value converted to a
solid content (silane coupling agent) and a value converted to P2O5 (phosphorous
compound), respectively.
The nitric acid compound, silane coupling agent and phosphorous
compound effectively contribute to the improvement of corrosion resistance. When
the ratio in the dry coating is not more than 30 mass% in total, unreacted substances do
not remain in the coating and the water resistance is not deteriorated, so that the content
is preferable to be not more than 30 mass% in total. In order to sufficiently develop
the effect of these components, it is preferable to include these components at a ratio of
not less than 1 mass% in the dry coating.
[0030] In the invention, nitric acid-based or nitrous acid-based compounds and
further hydrates thereof as shown below are advantageously suitable as the nitric acid
compound.
-Nitric acid-based:
nitric acid (HNO3), potassium nitrate (KNO3), sodium nitrate (NaNO3),
ammonium nitrate (NH4NO3), calcium nitrate (Ca(NO3)2), silver nitrate (AgNO3), iron
(II) nitrate (Fe(NO3)2), iron (III) nitrate (Fe(NO3)3), copper (II) nitrate (Cu(NO3)2),
barium nitrate (Ba(NO3)2), aluminum nitrate (Al(NO3)3), magnesium nitrate
(Mg(NO3)2), zinc nitrate (Zn(NO3)2), nickel (II) nitrate (Ni(NO3)2), zirconium nitrate
(ZrO(NO3)2).
-Nitrous acid-based:
nitrous acid (HNO2), potassium nitrite, calcium nitrite, silver nitrite, sodium
nitrite, barium nitrite, ethyl nitrite, isoamyl nitrite, isobutyl nitrite, isopropyl nitrite, tbutyl
nitrite, n-butyl nitrite, n-propyl nitrite.
[0031] As the silane coupling agent are advantageously suitable those shown below.
-Vinyl-based:
vinyl trichlorosilane, vinyl trimethoxysilane, vinyl triethoxysilane.
-Epoxy-based:
2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-glycidoxypropyl
trimethoxysilane, 3-glycidoxypropylmethyl diethoxysilane, 3-glycidoxypropyl
triethoxysilane.
-Styryl-based:
p-styryl trimethoxysilane.
-Methacryloxy-based:
3-methacryloxy propylmethyl dimethoxysilane, 3-methacryloxy propyl
10
trimethoxysilane, 3-methacryloxy propylmethyl diethoxysilane, 3-methacryloxy propyl
triethoxysilane.
-Acryloxy-based:
3-acryloxy propyl trimethoxysilane.
-Amino-based:
N-2-(aminoethyl)-3-aminopropylmethyl dimethoxysilane, N-2-
(aminoethyl)-3-aminopropyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropyl
triethoxysilane, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-
triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine and a partial hydrolyzate thereof,
N-phenyl-3-aminopropyl trimethoxysilane, hydrochloride of N-(vinylbenzyl)-2-
aminoethyl-3-aminopropyl trimethoxysilane, special aminosilanes.
-Ureido-based:
3-ureidopropyl triethoxysilane.
-Chloropropyl-based:
3-chloropropyl trimethoxysilane.
-Mercapto-based:
3-mercaptopropylmethyl dimethoxysilane, 3-mercaptopropyl
trimethoxysilane.
-Polysulfide-based:
bis(triethoxysilylpropyl)tetrasulfide.
-Isocyanate-based:
3-isocyanatepropyl triethoxysilane.
[0032] Furthermore, phosphoric acid and phosphates as shown below are
advantageously suitable as the phosphorous compound.
-Phosphoric acid:
orthophosphoric acid, phosphoric acid anhydride, linear polyphosphoric
acid, cyclic metaphosphoric acid.
-Phosphate:
Magnesium phosphate, aluminum phosphate, calcium phosphate, zinc
phosphate.
[0033] In the invention, Hf, HfO2, TiO2, Fe2O3 and so on may be incorporated into
the inorganic component as an impurity. However, a problem does not particularly
occurs when the total amount of these impurities is not more than 1 mass% in the dry
coating.
[0034] In the invention, it is preferable that the organic resin is compounded at a
ratio of 5 to 40 mass% so as to render the content of the inorganic component as
11
mentioned above in the dry coating into 60 to 95 mass%.
In the invention, the organic resin is not particularly limited and any of
known ones conventionally used are advantageously suitable. The organic resin
includes, for example, aqueous resins (emulsion, dispersion, water soluble) of acryl
resin, alkyd resin, polyolefin resin, styrene resin, vinyl acetate resin, epoxy resin, phenol
resin, polyester resin, urethane resin, melamine resin and so on. Emulsions of acryl
resin and ethylene acrylate resin are particularly preferable.
[0035] The organic resins effectively contribute to the improvement of the
corrosion resistance, scratch resistance and punchability. When the compounding ratio
in the dry coating is not less than 5 mass%, the addition effect is large, while when it is
not more than 40 mass%, the scratch resistance after stress relief annealing and TIG
weldability are not deteriorated, so that the compounding ratio of the organic resin is
preferable to be about 5 to 40 mass% as converted to a solid content.
[0036] It should be noted that the ratio in the dry coating refers to a ratio of each
component in a coating formed on a surface of a steel sheet by applying a treating
solution containing the aforementioned components onto the steel sheet, and drying by
baking. It can also be determined from residual components (solid content) after
drying the treating solution at 180°C for 30 minutes.
[0037] Furthermore, the invention does not interrupt the inclusion of additives
usually used and other inorganic or organic compounds in addition to the
aforementioned components.
The additive is added for further enhancing performances and uniformity of
the insulation coating, and includes a surfactant, an antirust agent, a lubricant, an
antioxidant and the like. Moreover, the amount of the additive compounded in the dry
coating is preferable to be not more than about 10 mass% from a viewpoint of the
maintaining of sufficient coating properties.
[0038] In the invention, the magnetic steel sheet as a starting material is not
particularly limited, and any known ones are suitable.
That is, any of so-called soft (magnetic) iron sheets (electric iron sheets)
having a high magnetic flux density, common cold-rolled steel sheets such as SPPC and
the like, non-oriented magnetic steel sheets containing Si and/or Al for increasing
specific electrical resistance and so on are advantageously suitable for reducing iron
loss. Particularly, it is preferable to use a steel sheet containing about 0.1 to 10 mass%
of Si or (Si + Al) and/or a steel sheet having an iron loss W15/50 of not more than about 7
W/kg.
[0039] Next, the method for forming the insulation coating will be described.
12
In the invention, a pretreatment of a magnetic steel sheet as a starting
material is not particularly defined. More specifically, the steel sheet may be untreated,
but it is advantageous to be subjected to a degreasing treatment with alkali or the like
and a pickling treatment with hydrochloric acid, sulfuric acid, phosphoric acid or the
like.
Then, to the surface of this magnetic steel sheet is applied a treating solution
formed by compounding a Zr compound and an Si compound containing a plate-like
silica, and optionally a B compound and optionally one or more selected from a nitric
acid compound, a silane coupling agent and a phosphorous compound, and, if necessary,
an additive and the like together with an organic resin at given ratios and then baked to
form an insulation coating. As a method for coating the treating solution for insulation
coatings are applicable various methods usually and industrially used such as roll coater,
flow coater, spray, knife coater and so on. Also, as the baking method are possible a
hot air type, an infrared type, an induction heating type and the like as generally
conducted. The baking temperature may be a normal level, and may be about 150 to
350°C as a maximum reaching temperature on the steel sheet.
[0040] The magnetic steel sheet with an insulation coating according to the
invention can remove strain due to punching, for example, by subjecting to stress relief
annealing. As a preferable stress relief annealing atmosphere is applied an atmosphere
hardly oxidizing iron such as N2 atmosphere, DX gas atmosphere or the like. Here, the
corrosion resistance can be further improved by setting a dew point high, for example
Dp: about 5 to 60°C to slightly oxidize the surface and cut end surface. Also, the
stress relief annealing temperature is preferably 700 to 900°C, more preferably 700 to
800°C. The holding time of the stress relief annealing temperature is preferably longer,
and more preferably not shorter than 2 hours.
[0041] The amount of the insulation coating adhered is not particularly limited, but
is preferably about 0.05 to 5 g/m2 per side. The coating amount or the total solid
content mass of the insulation coating according to the invention can be measured from
weight reduction after the removal of the coating through dissolving with alkali. If the
coating amount is small, it can be determined by using a standard sample having a
known coating amount and measuring a relationship between a detection intensity of Zr
or Si by a fluorescent X-ray analysis and the coating amount per coating composition
and converting the fluorescent X-ray analyzed intensity of Zr or Si into a coating
amount depending upon the coating composition based on this calibration curve.
When the coating amount is not less than 0.05 g/m2, the insulation property can be
satisfied with the corrosion resistance, while when it is not more than 5 g/m2, not only
13
the adhesion property is improved, but also blistering is not caused in the coat baking,
and the deterioration of coatability is not incurred. More preferably, it is 0.1 to 3.0
g/m2. Although it is preferable to form insulation coatings on the both sides of the
steel sheet, the coating may be formed on only one side depending on the purpose. In
addition, the coating is formed on only one side and another insulation coating may be
formed on the other side depending on the purpose.
EXAMPLES
[0042] Although the effect of the invention will be concretely described based on
examples below, the invention is not limited to these examples.
Example 1
A treating solution is prepared by adding a Zr compound and an Si
compound containing a plate-like silica and further a nitric acid compound, a silane
coupling agent, a phosphorus compound and an additive to a deionized water together
with an organic resin so that components of an insulation coating after drying are shown
in Tables 1-1 and 1-2. Moreover, the addition concentration to the deionized water is
50g/l.
Each of these treating solutions is applied to a surface of a test piece with a
size of 150 mm in width and 300 mm in length cut out from a magnetic steel sheet
[A230 (JIS C 2552 (2000))] of 0.5 mm in thickness by means of a roll coater, baked in a
hot air baking oven at a baking temperature (temperature arriving in steel sheet) shown
in Tables 1-1 and 1-2, and then allowed to cool to room temperature to form insulation
coatings on the both sides.
[0043] The results examined on the corrosion resistance and powdering resistance
of the thus obtained magnetic steel sheets with semi-insulation coatings are shown in
Table 2.
Further, the scratch resistance after the steel sheets are subjected to stress
relief annealing in a nitrogen atmosphere at 750°C for 2 hours, the scratch resistance,
sticking resistance, TIG weldability, punchability, water resistance, and appearance
after stress relief annealing are examined to obtain results also shown in Table 2.
[0044] Moreover, types of the Zr compound are shown in Table 3, types of the Si
compound are shown in Table 4, types of the phosphorous compound and nitric acid
compound are shown in Table 5, types of the silane coupling agent are shown in Table 6,
and types of the organic resin are shown in Table 7.
[0045] Also, the evaluation method for each property is as follows.

The humidity cabinet test (50°C, relative humidity ≥ 98%) is conducted to
14
the test piece, and a rate of developing red rust after 48 hours is visually observed and
evaluated as an area ratio.
(Criteria)
☆: red rust area ratio less than 5 %
◎: red rust area ratio not less than 5 % but less than 15 %
○: red rust area ratio not less than 15 % but less than 40 %
△: red rust area ratio not less than 40 % but less than 60 %
×: red rust area ratio not less than 60 %
[0046]
Test conditions; Felt contact face width: 20 mm × 10 mm, load: 0.4 MPa
(3.8 kg/cm2), 100 times of simple reciprocation on a coating surface. Scratch marks
after the test are visually observed to evaluate an exfoliated state and a powdered state
of the coating.
(Criteria)
◎: coating residual ratio any scratch mark is hardly observed
○: coating residual ratio slight scratch marks and slight powdering are
observed
△: coating residual ratio abrasion of the coating progresses, and scratch
marks and powdering are clearly observed
×: coating residual ratio reach to expose an iron substrate, and powdering
dust is severe
[0047]
The surface of the sample annealed under test condition of holding in an N2
atmosphere at 750°C for 2 hours is scratched by a steel sheet shear edge to judge the
degrees of scratch and powdering.
(Criteria)
◎: any occurrence of scratch and powdering is hardly observed
○: slight scratch marks and slight powdering are observed
△: scratch marks and powdering are clearly observed
×: reach to expose an iron substrate, and scratch dust is severe
[0048]
10 test sample sheets with 50 mm square are stacked and annealed in a
nitrogen atmosphere at 750°C for 2 hours while applying a load: 20 kPa (200 g/cm2).
Then, 500 g of weight is dropped on the test samples (steel sheets) to measure a drop
height when the test sample sheets are divided into five pieces.
(Criteria)
15
◎: not more than 10 cm
○: more than 10 cm but not more than 15 cm
△: more than 15 cm but not more than 30 cm
×: more than 30 cm
[0049]
The test samples are laminated under a pressure of 9.8 MPa (100 kgf/cm2)
so as to have a thickness of 30 mm, and an end face portion thereof (length 30 mm) is
subjected to TIG welding under the following conditions:
-welding current: 120 A
-Ar gas flow rate: 6 liter/min
-welding speed: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 cm/min
(Criteria)
Relative merits are judged by the welding speed satisfying the number of
blowholes of not more than 5 per bead.
◎: not less than 60 cm/min
○: not less than 40 cm/min but less than 60 cm/min
△: not less than 20 cm/min but less than 40 cm/min
×: less than 20 cm/min
[0050]
The test sample is subjected to punching with a 15 mm steel dice until a
burr height reaches to 50 μm, and the evaluation is represented by the number of
punchings.
(Criteria)
◎: not less than 1,200,000 times
○: not less than 500,000 times but less than 1,200,000 times
△: not less than 100,000 times but less than 500,000 times
×: less than 100,000 times
[0051]
The test sample is exposed in a steam above a boiling water for 30 minutes
to observe an appearance change.
(Criteria)
◎: no change
○: slight change of color is visually observed
△: clear change of color is visually observed
×: coating dissolved
[0052]
16
An appearance of a steel sheet is visually observed by holding the test
sample in an N2 atmosphere at 750°C for 2 hours and then cooling to room temperature.
(Criteria)
◎: appearance after annealing is completely uniform as shown in FIG.1(a)
○: unevenness in appearance after annealing as shown in FIG.1(b)
△: spotted pattern in appearance after annealing as shown in FIG.1(c)
×: remarkable spotted pattern in appearance after annealing as shown in
FIG.1(d)
17
[0053] Table 1-1
Table1-1
Type in
Table 3
Addition
amount
(converted to
ZrO2)(mass%)
Type* in
Table 4
Addition
amount
(converted to
SiO2)(mass%)
Type in
Table 5
Addition amount
(converted to
P2O5%)(mass%)
Type in
Table 5
Addition
amount
(converted to
NO3)(mass%)
Type in
Table 6
Addition amount
(converted to
solid
content)(mass%)
1 Z1 60 S2(100) 22 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 1
2 Z1 50 S2(80) 22 - 0 - 0 - 0 R1 28 250 0.3 Invention
Example 2
3 Z1 70 S2(100) 12 - 0 - 0 - 0 R1 18 250 0.4 Invention
Example 3
4 Z1 55 S2(50) 15 - 0 - 0 - 0 R1 38 250 0.5 Invention
Example 4
5 Z1 57 S2(70) 35 - 0 - 0 - 0 R1 8 250 0.5 Invention
Example 5
6 Z2 50 S2(80) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 6
7 Z3 50 S2(50) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 7
8 Z4 50 S2(40) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 8
9 Z5 50 S2(30) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 9
10 Z6 50 S2(20) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 10
11 Z1 50 S1(100) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 11
12 Z1 50 S3(80) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 12
13 Z1 50 S4(80) 32 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 13
14 Z1 40 S2(100) 22 P1 30 - 0 - 0 R1 8 250 0.5 Invention
Example 14
15 Z1 40 S2(50) 22 P2 30 - 0 - 0 R1 8 250 0.5 Invention
Example 15
16 Z1 40 S2(100) 22 - 0 N1 30 - 0 R1 8 250 0.5 Invention
Example 16
17 Z1 40 S2(50) 22 - 0 N1 30 - 0 R1 8 250 0.5 Invention
Example 17
18 Z1 40 S2(80) 22 - 0 - 0 C11 30 R1 8 250 0.5 Invention
Example 18
*Inside ( ) shows the ratio (mass%) of plate-like silica in Si compound. The remainder is S0 (colloidal silica).
No. Components of insulation coating Baking
temperature
(C)
Coating
amount of
insulation
coating (g/m2)
Compounding
amount in dry
coating
(mass%)
Remarks
Inorganic component Arbitrary addition component Organic resin
Zr compound Si compound Phosphorus compound Nitric acid compound Silane coupling agent type in
Table 7
18
[0054] Table 1-2
Table1-2
Type in
Table 3
Addition
amount
(converted to
ZrO2)(mass%)
Type* in
Table 4
Addition
amount
(converted to
SiO2)(mass%)
Type in
Table 5
Addition amount
(converted to
P2O5)(mass%)
Type in
Table 5
Addition
amount
(converted to
NO3)(mass%)
Type in
Table 6
Addition amount
(converted to
solid
content)(mass%)
19 Z1 40 S2(80) 22 - 0 - 0 C12 30 R1 8 250 0.5 Invention
Example 19
20 Z1 40 S2(80) 22 - 0 - 0 C13 30 R1 8 250 0.5 Invention
Example 20
21 Z1 50 S2(100) 32 - 0 - 0 - 0 R1 18 250 0.03 Invention
Example 21
22 Z1 50 S2(100) 32 - 0 - 0 - 0 R1 18 250 5 Invention
Example 22
23 Z1 50 S2(80) 32 - 0 - 0 - 0 R2 18 250 0.5 Invention
Example 23
24 Z1 50 S2(80) 32 - 0 - 0 - 0 R3 18 250 0.5 Invention
Example 24
25 Z1 50 S2(80) 32 - 0 - 0 - 0 R4 18 250 0.5 Invention
Example 25
26 Z1 10 S2(80) 32 - 0 - 0 - 0 R1 58 250 0.3 Comparative
Example 1
27 Z1 80 S2(80) 12 - 0 - 0 - 0 R1 8 250 0.4 Comparative
Example 2
28 Z1 50 S2(80) 5 - 0 - 0 - 0 R1 45 250 0.5 Comparative
Example 3
29 Z1 32 S2(80) 60 - 0 - 0 - 0 R1 8 250 0.5 Comparative
Example 4
30 Z1 30 S2(100) 12 P1 50 - 0 - 0 R1 8 250 0.5 Comparative
Example 5
31 Z1 30 S2(50) 12 P2 50 - 0 - 0 R1 8 250 0.5 Comparative
Example 6
32 Z1 30 S2(100) 12 - 0 N1 50 - 0 R1 8 250 0.5 Comparative
Example 7
33 Z1 30 S2(50) 12 - 0 N2 50 - 0 R1 8 250 0.5 Comparative
Example 8
34 Z1 30 S2(100) 12 - 0 - 0 C11 50 R1 8 250 0.5 Comparative
Example 9
35 Z1 30 S2(100) 12 - 0 - 0 C12 50 R1 8 250 0.5 Comparative
Example 10
36 Z1 30 S2(100) 12 - 0 - 0 C13 50 R1 8 250 0.5 Comparative
Example 11
37 Z1 50 only SO 42 - 0 - 0 - 0 R1 8 250 0.5 Comparative
Example 12
*Inside ( ) shows a ratio (mass%) of plate-like silica in Si compound. The remainder is S0 (colloidal silica).
No. Components of insulation coating Baking
temperatur
e (C)
Coating
amount of
insulation
coating
(g/m2)
Compounding
amount in dry
coating (mass%)
Remarks
Inorganic components Arbitrary addition components Organic resin
Zr compound Si compound Phosphorus compound Nitric acid compound Silane coupling agent Type in
Table 7
19
[0055] Table 2
Table 2
Corrosion
resistance
Powdering
resistance
Scratch
resistance after
annealing
Sticking
resistance
TIG
weldability
Punchability Water
resistance
Appearance
after
annealing
1 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 1
2 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 2
3 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 3
4 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 4
5 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 5
6 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 6
7 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 7
8 ◯ ◯ ◎ ◎ ◎ ◯ ◎ ◎ Invention Example 8
9 ◯ ◯ ◎ ◎ ◎ ◯ ◎ ◎ Invention Example 9
10 ◯ ◯ ◎ ◎ ◎ ◯ ◎ ◎ Invention Example 10
11 ◯ ◯ ◎ ◎ ◎ ◯ ◎ ◎ Invention Example 11
12 ◯ ◯ ◎ ◎ ◎ ◯ ◎ ◎ Invention Example 12
13 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 13
14 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 14
15 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 15
16 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 16
17 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 17
18 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 18
19 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 19
20 ☆ ◯ ◎ ◎ ◎ ◎ ◯ ◎ Invention Example 20
21 ◯ ◯ ◯ ◎ ◎ ◯ ◯ ◎ Invention Example 21
22 ◎ ◯ ◯ ◎ ◯ ◎ ◎ ◯ Invention Example 22
23 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 23
24 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 24
25 ◎ ◯ ◎ ◎ ◎ ◎ ◎ ◎ Invention Example 25
26 × × × ◎ × ◎ ◎ × Comparative Example 1
27 × × × ◎ ◎ ◎ ◎ ◎ Comparative Example 2
28 △ △ △ ◎ △ ◎ ◎ ◎ Comparative Example 3
29 △ × × ◎ ◎ △ ◎ ◎ Comparative Example 4
30 △ △ △ ◎ ◎ ◎ △ ◎ Comparative Example 5
31 △ △ △ ◎ ◎ △ × △ Comparative Example 6
32 △ △ △ ◎ ◎ ◎ × ◎ Comparative Example 7
33 △ △ △ ◎ ◎ △ × △ Comparative Example 8
34 △ △ △ ◎ ◎ ◎ × ◎ Comparative Example 9
35 △ △ △ ◎ ◎ ◎ × ◎ Comparative Example 10
36 △ △ △ ◎ ◎ ◎ × ◎ Comparative Example 11
37 × △ △ ◯ ◎ × × × Comparative Example 12
No. Coating properties Remarks
20
[0056] Table 3
Symbol Name Chemical formula Manufacturer Trade
name
Z1 Ammonium
zirconium
carbonate
(NH4)2[Zr(CO3)2(OH2)] Daiichi Kigenso
Kagaku Co., Ltd.
Zircosol
AC-20
Z2 Potassium
zirconium
carbonate
K2[Zr(CO3)2(OH2)] Nippon Light
Metal Co., Ltd.
Zirmel
1000
Z3 Zirconium acetate (CH3CO2)nZr Daiichi Kigenso
Kagaku Co., Ltd.
Zircosol
ZA-20
Z4 Zirconium sulfate H2Zr(OH)2(SO4)2 Nippon Light
Metal Co., Ltd.
-
Z5 Zirconium nitrate ZrO(NO3)2 Nippon Light
Metal Co., Ltd.
-
Z6 Potassium
zirconium
hexafluoride
K2ZrF6 Mitsubishi
Materials
Electronic
Chemicals Co.,
Ltd.
-
[0057] Table 4
Symbol Content
S0 Colloidal silica with average particle size: 13 nm
S1 Plate-like silica with average particle size: 50 nm,
aspect ratio: 2
S2 Plate-like silica with average particle size: 200 nm,
aspect ratio: 10
S3 Plate-like silica with average particle size: 600 nm,
aspect ratio: 400
S4 Plate-like silica with average particle size: 300 nm,
aspect ratio: 20
21
[0058] Table 5
Symbol Name Chemical formula
P1 Orthophosphoric acid H3PO4
P2 Ammonium phosphate (NH4)3PO4
N1 Nickel nitrate Ni(NO3)2∙6H2O
N2 Zirconium nitrate ZrO(NO3)2
[0059] Table 6
Symbol Name
CI1 Vinyltrimethoxysilane
CI2 3-glycidoxypropyltrimethoxysilane
CI3 N-2-(aminoethyl)-3-
aminopropylmethyldimethoxysilane
[0060] Table 7
Symbol Name Manufacturer Trade name
R1 Epoxy resin ADEKA
Corporation
ADEKA RESIN EM
R2 Polyester
resin
TOYOBO Co., Ltd. Vylonal MD1200
R3 Acryl resin DIC Corporation VONCOAT CP6140
R4 Urethane
resin
ADEKA
Corporation
ADEKA BONTIGHTER HUX
[0061] As shown in Table 2, all of the magnetic steel sheets with a semi-organic
insulation coating obtained according to the invention are excellent in not only the
corrosion resistance and powdering resistance but also the scratch resistance after stress
relief annealing, sticking resistance, TIG weldability, punchability and water resistance,
and further excellent in the appearance after stress relief annealing.
On the other hand, Comparative Examples 1 and 2, wherein the amount of
Zr compound is out of the adequate range, are particularly poor in the corrosion
resistance, powdering resistance and scratch resistance after annealing. Comparative
Example 1 is also poor in the TIG weldability and appearance after annealing.
22
Also, Comparative Example 3, wherein the amount of Si compound is less
than the lower limit, is poor in the corrosion resistance, powdering resistance, scratch
resistance after annealing and TIG weldability, while Comparative Example 4, wherein
the amount of Si compound is more than the upper limit, is particularly poor in the
powdering resistance and scratch resistance after annealing.
Furthermore, all of Comparative Examples 5 to 11 containing an amount of
nitric acid compound or silane coupling agent or phosphorous compound exceeding
over the adequate range are poor in the corrosion resistance, powdering resistance,
scratch resistance after annealing and water resistance.
Moreover, Comparative Example 12 using only colloidal silica without
plate-like silica as an Si compound is particularly poor in the corrosion resistance,
punchability, water resistance and appearance after annealing, and is also not as good as
Inventive Examples in the powdering resistance and scratch resistance after annealing.
[0062] Example 2
A treating solution is prepared by adding a Zr compound, a B compound
and a Si compound containing a plate-like silica, and further a nitric acid compound, a
silane coupling agent, a phosphorous compound or an additive to a deionized water
together with an organic resin so that components of an insulation coating after drying
are shown in Tables 8-1 and 8-2. Moreover, the addition concentration to the
deionized water is 50g/l.
Each of these treating solutions is applied onto surfaces of a test piece with
a size of 150 mm in width and 300 mm in length, which is cut out from a magnetic steel
sheet [A230 (JIS C 2552 (2000))] of 0.5 mm in thickness, by means of a roll coater,
baked in a hot air baking oven at a baking temperature (maximum reaching temperature
on steel sheet) shown in Tables 8-1 and 8-2, and then allowed to cool to room
temperature to form insulation coatings on the both sides.
[0063] The results examined on the corrosion resistance and powdering resistance
of the thus obtained magnetic steel sheet with semi-insulation coatings are shown in
Table 9.
Further, the scratch resistance the steel sheets are subjected to stress relief
annealing in a nitrogen atmosphere at 750°C for 2 hours, the scratch resistance, sticking
resistance, TIG weldability, punchability, water resistance, and appearance after stress
relief annealing are examined to obtain results also shown in Table 9.
Moreover, the type of the B compound is shown in Table 10.
Also, the evaluation method for each property is the same as Example 1.
23
[0064] Table 8-1
Table 8-1
Type in
Table 3
Addition
amount
(converted to
ZrO2)(mass%)
Type in
Table 10
Addition
amount
(converted to
B2O3)(mass%)
Type* in
Table 4
Addition
amount
(converted to
SiO2)(mass%)
Type in
Table 5
Addition amount
(converted to
P2O5%)(mass%)
Type in
Table 5
Addition
amount
(converted to
NO3)(mass%)
Type in
Table 6
Addition amount
(converted to
solid
content)(mass%)
1 Z1 50 B1 2 S2(100) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 1
2 Z1 20 B1 2 S2(80) 50 - 0 - 0 - 0 R1 28 250 0.3 Invention
Example 2
3 Z1 70 B1 2 S2(100) 10 - 0 - 0 - 0 R1 18 250 0.4 Invention
Example 3
4 Z1 50 B1 0.1 S2(50) 30 - 0 - 0 - 0 R1 19.9 250 0.6 Invention
Example 4
5 Z1 50 B1 5 S2(70) 30 - 0 - 0 - 0 R1 15 250 0.2 Invention
Example 5
6 Z1 50 B1 2 S2(80) 10 - 0 - 0 - 0 R1 38 250 0.5 Invention
Example 6
7 Z1 40 B1 2 S2(50) 48 - 0 - 0 - 0 R1 10 250 0.5 Invention
Example 7
8 Z2 50 B1 2 S2(40) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 8
9 Z3 50 B1 2 S2(30) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 9
10 Z4 50 B1 2 S2(20) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 10
11 Z5 50 B1 2 S2(100) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 11
12 Z6 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 12
13 Z1 50 B1 2 S1(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 13
14 Z1 50 B1 2 S3(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 14
15 Z1 50 B1 2 S4(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 15
16 Z1 40 B1 2 S2(100) 18 P1 30 - 0 - 0 R1 10 250 0.5 Invention
Example 16
17 Z1 40 B1 2 S2(50) 18 P2 30 - 0 - 0 R1 10 250 0.5 Invention
Example 17
18 Z1 40 B1 2 S2(100) 18 - 0 N1 30 - 0 R1 10 250 0.5 Invention
Example 18
19 Z1 40 B1 2 S2(50) 18 - 0 N2 30 - 0 R1 10 250 0.5 Invention
Example 19
20 Z1 40 B1 2 S2(80) 18 - 0 - 0 C11 30 R1 10 250 0.5 Invention
Example 20
*Inside ( ) shows the ratio (mass%) of plate-like silica in Si compound. The remainder is S0 (colloidal silica).
No. Components of insulation coating Baking
temperature
(C)
Coating
amount of
insulation
coating
(g/m2)
type in
Table
7
Compounding
amount in dry
coating
(mass%)
Remarks
Inorganic component Arbitrary addition component Organic resin
Zr compound B compound Si compound Phosphorus compound Nitric acid compound Silane coupling agent
24
[0065] Table 8-2
Table 8-2
Type in
Table 3
Addition
amount
(converted to
ZrO2)(mass%)
Type in
Table 10
Addition
amount
(converted to
B2O3)(mass%)
Type* in
Table 4
Addition
amount
(converted to
SiO2)(mass%)
Type in
Table 5
Addition amount
(converted to
P2O5%)(mass%)
Type
in
Table
5
Addition amount
(converted to
NO3)(mass%)
Type
in
Table
6
Addition amount
(converted to
solid
content)(mass%)
21 Z1 38 B1 2 S2(80) 20 - 0 - 0 C12 30 R1 10 250 0.5 Invention
Example 21
22 Z1 38 B1 2 S2(80) 20 - 0 - 0 C13 30 R1 10 250 0.5 Invention
Example 22
23 Z1 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 0.03 Invention
Example 23
24 Z1 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 5 Invention
Example 24
25 Z1 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 25
26 Z1 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 26
27 Z1 50 B1 2 S2(80) 30 - 0 - 0 - 0 R1 18 250 0.5 Invention
Example 27
28 Z1 10 B1 2 S2(80) 30 - 0 - 0 - 0 R1 58 250 0.3 Comparative
Example 1
29 Z1 78 B1 2 S2(80) 10 - 0 - 0 - 0 R1 10 250 0.4 Comparative
Example 2
30 Z1 50 B1 10 S2(100) 30 - 0 - 0 - 0 R1 10 250 0.2 Comparative
Example 3
31 Z1 50 B1 2 S2(80) 3 - 0 - 0 - 0 R1 45 250 0.5 Comparative
Example 4
32 Z1 28 B1 2 S2(80) 60 - 0 - 0 - 0 R1 10 250 0.5 Comparative
Example 5
33 Z1 28 B1 2 S2(100) 10 P1 50 - 0 - 0 R1 10 250 0.5 Comparative
Example 6
34 Z1 28 B1 2 S2(50) 10 P2 50 - 0 - 0 R1 10 250 0.5 Comparative
Example 7
35 Z1 28 B1 2 S2(100) 10 - 0 N1 50 - 0 R1 10 250 0.5 Comparative
Example 8
36 Z1 28 B1 2 S2(50) 10 - 0 N1 50 - 0 R1 10 250 0.5 Comparative
Example 9
37 Z1 28 B1 2 S2(80) 10 - 0 - 0 C11 50 R1 10 250 0.5 Comparative
Example 10
38 Z1 28 B1 2 S2(80) 10 - 0 - 0 C12 50 R1 10 250 0.5 Comparative
Example 11
39 Z1 28 B1 2 S2(80) 10 - 0 - 0 C13 50 R1 10 250 0,5 Comparative
Example 12
40 Z1 30 B1 10 only SO 50 - 0 - 0 - 0 R1 10 250 0.5 Comparative
Example 13
*Inside ( ) shows the ratio (mass%) of plate-like silica in Si compound. The remainder is S0 (colloidal silica).
No. Components of insulation coating Baking
temperature (C)
Coating amount
of insulation
coating (g/m2) type in
Table 7
Compounding
amount in dry
coating (mass%)
Remarks
Inorganic component Arbitrary addition component Organic resin
Zr compound B compound Si compound Phosphorus compound Nitric acid compound Silane coupling agent
25
[0066] Table 9
Table 9
Corrosion
resistance
Powdering
resistance
Scratch
resistance after
annealing
Sticking
resistance
TIG
weldability
Punchability Water
resistance
Appearance
after
annealing
26
[0067] Table 10
Symbol Name Chemical formula
B1 Boric acid H3BO3
[0068] As shown in Table 9, all of the magnetic steel sheets with a semi-organic
insulation coating obtained according to the invention are excellent in not only the
corrosion resistance and powdering resistance but also the scratch resistance after stress
relief annealing, sticking resistance, TIG weldability, punchability and water resistance,
and further excellent in the appearance after stress relief annealing.
On the other hand, Comparative Examples 1 and 2, wherein the amount of
Zr compound is out of the adequate range, are particularly poor in the corrosion
resistance, powdering resistance and scratch resistance after annealing. Comparative
Example 1 is also poor in the TIG weldability and appearance after annealing.
Also, Comparative Example 3, wherein the amount of B compound is more
than the upper limit, is particularly poor in the sticking resistance.
Comparative Example 4, wherein the amount of Si compound is less than
the lower limit, is poor in the corrosion resistance and TIG weldability, while
Comparative Example 5, wherein the amount of Si compound is more than the upper
limit, is particularly poor in the powdering resistance and scratch resistance after
annealing.
Furthermore, all of Comparative Examples 6 to 12 containing an amount of
nitric acid compound or silane coupling agent or phosphorous compound exceeding
over the adequate range are poor in the corrosion resistance and water resistance.
Moreover, Comparative Example 13 using only colloidal silica without
plate-like silica as an Si compound is particularly poor in the corrosion resistance, water
resistance and appearance after annealing, and is also not as good as Inventive
Examples in the powdering resistance, scratch resistance after annealing, sticking
resistance and punchability.
27
We claim:
1. A magnetic steel sheet provided on its surface with a semi-organic
insulation coating comprising an inorganic component and an organic resin,
characterized in that the inorganic component of the coating comprises a Zr compound
and an Si compound containing a plate-like silica as a ratio in a dry coating of 20-70
mass% of Zr compound (converted to ZrO2) and 10-50 mass% of Si compound
containing a plate-like silica (converted to SiO2), and the remainder of the coating is the
organic resin.
2. The magnetic steel sheet with a semi-organic insulation coating
according to claim 1, wherein the plate-like silica has an average particle size of 10 to
600 nm.
3. The magnetic steel sheet with a semi-organic insulation coating
according to claim 1 or 2, wherein the plate-like silica has an aspect ratio (average
length/average thickness ratio) of 2 to 400.
4. The magnetic steel sheet with a semi-organic insulation coating
according to any one of claims 1 to 3, wherein the inorganic component further contains
a B compound as a ratio in a dry coating of 0.1-5 mass% of B compound (converted at
B2O3 ).
5. The magnetic steel sheet with a semi-organic insulation coating
according to any one of claims 1 to 4, wherein the coating further contains not more
than 30 mass% in total of one or more selected from a nitric acid compound (converted
to NO3), a silane coupling agent (converted to a solid content) and a phosphorus
compound (converted to P2O5) as a ratio in a dry coating.

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Patent Number

277889

Indian Patent Application Number

2787/MUMNP/2012

PG Journal Number

51/2016

Publication Date

09-Dec-2016

Grant Date

05-Dec-2016

Date of Filing

14-Dec-2012

Name of Patentee

JFE STEEL CORPORATION

Applicant Address

2-3 Uchisaiwai-cho 2-chome Chiyoda-ku Tokyo 1000011 Japan.

Inventors:

#	Inventor's Name	Inventor's Address
1	SASHI Kazumichi	c/o Intellectual Property Dept. JFE STEEL CORPORATION 2-3 Uchisaiwai-cho 2-chome Chiyoda-ku Tokyo 1000011 Japan.
2	OGATA Hiroyuki	c/o Intellectual Property Dept. JFE STEEL CORPORATION 2-3 Uchisaiwai-cho 2-chome Chiyoda-ku Tokyo 1000011 Japan.
3	TADA Chiyoko	c/o Intellectual Property Dept. JFE STEEL CORPORATION 2-3 Uchisaiwai-cho 2-chome Chiyoda-ku Tokyo 1000011 Japan.
4	NAKAGAWA Nobuko	c/o Intellectual Property Dept. JFE STEEL CORPORATION 2-3 Uchisaiwai-cho 2-chome Chiyoda-ku Tokyo 1000011 Japan.
5	FUJIBAYASHI Nobue	c/o Intellectual Property Dept. JFE STEEL CORPORATION 2-3 Uchisaiwai-cho 2-chome Chiyoda-ku Tokyo 1000011 Japan.
6	SHIGEKUNI Tomofumi	c/o Intellectual Property Dept. JFE STEEL CORPORATION 2-3 Uchisaiwai-cho 2-chome Chiyoda-ku Tokyo 1000011 Japan.
7	SASAKI Kenichi	c/o Intellectual Property Dept. JFE STEEL CORPORATION 2-3 Uchisaiwai-cho 2-chome Chiyoda-ku Tokyo 1000011 Japan.

PCT International Classification Number

C23C22/00,B32B15/08

PCT International Application Number

PCT/JP2011/004123

PCT International Filing date

2011-07-21

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2010-165380	2010-07-22	Japan