RU2386725C2 - Textured electrotechnical steel plate having insulating film not containing chrome, and insulating film agent - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: textured electrotechnical steel plate has insulating film not containing chrome; at that, insulating film includes phosphate and one or more colloid substances chosen from non-organic compounds Fe, Ni, Co, Cu, Sr, and Mo containing metal elements of 0.06 to 2.10 mol per mol of one or more types of primary phosphates chosen from Al, Mg, Ca, Ni, and Co on the basis of metal ions and having the size of grains of colloid substances Fe, Ni, Co, Cu, Sr, and Mo of 50 nm or less.

EFFECT: obtaining insulating film for textured electrotechnical steel plate, which has high corrosion resistance, annealing resistance, film tension.

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Description

Field of Invention

The present invention relates to an insulating film formation technology for a textured electrical steel sheet, provides a chromium-free processing solution in more detail, and relates to a product using this and having excellent insulating film properties such as annealing resistance, film tension, insulation, adhesion, corrosion resistance and the like, and a method for forming an insulating film.

State of the art

A textured electrical steel sheet is obtained by hot rolling a silicon steel plate containing Si, for example, in an amount of 2 to 4%, annealing it, then cold rolling it once or twice or more, annealing between rolling, to obtain a final sheet thickness, then fabrication of the final product by annealing it with decarbonization, then applying a release agent for annealing, mainly containing MgO, performing the final annealing in order to cause secondary recrystallization having the Goss orientation, further e removing S, N and other impurities, forming a glass film, then applying an insulating film agent, and drying and thermally leveling the sheet.

The textured electrical steel sheet obtained in this way is usually used in electrical equipment, transformers and the like as a core material and should have a high magnetic flux density and high core losses. When a textured electrical steel sheet is used as the core of a transformer, the winding of a textured electrical steel sheet is cut, cut to predetermined distances that are continuously unwound, and laid or wound using a core processing machine to form a multi-tiered core and a tape core. In the case of a tape core, for the manufacture of a transformer, compression, annealing with stress relieving and a winding called “lacing” are performed. In this method of manufacturing a transformer, it is important that cutting, winding and processing can be performed without difficulty. In particular, it is also important in the manufacture of the tape core that the adhesion of the insulating film is excellent during cutting and winding and dust formation is excluded, as well as the ability to winding and resistance to annealing are excellent and the film performance, magnetic properties and performance are not deteriorated.

The surface of a textured electrical steel sheet film typically comprises a forsterite film formed upon completion of annealing and commonly referred to as a “glass film” and an insulating film deposited on top. According to the technology of formation of this insulating film, an elastic film containing colloidal silicon dioxide, phosphate and a chromium compound is conceived, disclosed and put into production by the inventors in Japanese Patent Publication (B2) No. 53-28375. Also, a treatment agent containing primary phosphate plus finely ground colloidal silicon dioxide with a grain size of 8 nm or less and a chromium compound are disclosed as shown in Japanese Patent Publication (A) No. 61-41778.

Moreover, Japanese Patent Publication (A) No. 3-39484 shows a technology for mixing colloidal silicon dioxide with a grain size of 20 nm or less and colloidal silicon dioxide with a grain size of 80 to 2000 nm with primary phosphates Al, Mg, Ca and Zn and a compound chromium to obtain the effect of uniform protrusion on the surface of the insulating film and improves the winding (sliding properties), resistance to annealing and film tension in the method of manufacturing a tape core. Due to this, good tension and processing ability of the core can be achieved, which provides a textured electrical steel sheet having excellent magnetic and magnetostrictive properties.

These insulating films have chromium compounds added and mixed with them, taking into account the hygroscopicity after drying the film with phosphate and the setting of the film during annealing with stress relieving.

The function of the chromium compound in the insulating film is to provide an improvement in film stickiness and film setting and tension during annealing and the like, along with the effect of filling the porous structure of the film in phosphate or film based on phosphate and colloidal silicon dioxide, and the fixing effect free phosphoric acid, which has hygroscopicity and degradability, which remains in the film and forms a stable compound of phosphoric acid and chromium after drying the insulating film. When the treatment solution uses chromic anhydride, chromate or dichromate and contains hexavalent chromium, problems arise in the production environment during coating and during waste treatment. Also, in the film after drying, when hexavalent Cr is converted to trivalent, the production environment becomes contaminated when dust is formed during the manufacture of the core. As a countermeasure against this, an insulating film agent containing no chromium compound was tested. Also, Japanese Patent Publication (B2) No. 57-9631 provides a method for forming an insulating film comprising drying a treatment solution containing 20 parts by weight of colloidal silicon dioxide as SiO ₂ , from 10 to 120 parts by weight of aluminum phosphate, from 2 to 10 parts by weight of boric acid and a total of 4 to 40 parts by weight of one or more ingredients selected from sulfates of Mg, Al, Fe, Co, Ni and Zn at 300 ° C or more.

Moreover, Japanese Patent Publication (A) No. 7-180064 discloses a treatment agent comprising a composite composition of a solid solution type hydroxide with an average grain size of 1 μm or less, represented by the general formula M ²⁺ _{1 x} M ³⁺ _x (OH) ^- _{2 + x-nu} A ^n- _y · mH ₂ O. Also, Japanese Patent Publication (A) No. 2000-178760 proposes a surface treatment agent for a textured electrical steel sheet, characterized by the addition of an organic acid salt selected from Ca, Mn, Fe, Mg, Zn, Co, Ni, Cu, B and Al of one or more salts of organic acids, in brane from formates, acetates, oxalates, tartrates, lactates, citrates, succinates, or salicylates.

All technologies are capable of demonstrating the effect of film tension and other effects. In the case of the technology proposed in Japanese Patent Publication (B2) No. 57-9631, there are problems with discoloration, insulation, corrosion resistance and the like, during annealing of added sulfates by sulfuric acid ions. The technology proposed in Japanese Patent Publication (A) No. 2000-178760 has a color tone problem due to an organic substance for dissolving metal elements and a solution stability problem. If we compare in this way with the traditional agent of the insulating film containing chromium, we can see that the film with the agent containing chromium is not effective enough.

Disclosure of invention

The present invention provides a textured electrical steel sheet having an insulating film having excellent film performance and an insulating film agent that solves problems with the production environment by incorporating an insulating film agent composition not containing a chromium compound and solves the problem of lower hygroscopicity, annealing resistance, the density and tension of the film in the absence of a chromium compound in a phosphate-based insulating film or a phosphate-based film and colloidal silicon dioxide.

The present invention has the following compositions of a textured electrical steel sheet having an insulating film not containing a chromium compound and an insulating film agent composition.

(1) A textured electrical steel sheet having an insulating film not containing chromium is characterized in that the insulating film contains phosphate and one or more inorganic compounds selected from inorganic compounds Fe, Ni, Co, Cu, Sr and Mo in an amount as metal elements, from 0.06 to 2.10 mol per 1 mol of this phosphate (based on metal ions).

(2) A textured electrical steel sheet having an insulating film not containing chromium is characterized in that the above inorganic compound Fe, Ni, Co, Cu, Sr, and Mo is one or more hydroxide, oxide, carbonate, silicate, and molybdate.

(3) A textured electrical steel sheet having an insulating film not containing chromium is also characterized by a content of from 35 to 100 parts by weight of SiO ₂ relative to 100 parts by weight of phosphate.

(4) An insulating film agent for a textured chromium-free electrical steel sheet is characterized by one or more inorganic compounds selected from inorganic compounds Fe, Ni, Co, Cu Sr, and Mo in an amount, as metal elements, from 0.06 up to 2.10 mol per 1 mol (based on metal ions) of the total content of one or more types of primary phosphates selected from Al, Mg, Ca, Ni and Co.

(5) An insulating film agent for a textured chromium-free electrical steel sheet is also characterized by the content of colloidal silicon dioxide in an amount, as a solid equivalent content, from 35 to 100 parts by weight relative to 100 parts by weight of the above phosphate.

(6) An insulating film agent for a textured electrical steel sheet having a chromium-free insulating film, characterized in that the above inorganic compound Fe, Ni, Co, Cu, Sr and Mo is one of or more hydroxide, oxide, carbonate, silicate and molybdate.

(7) An insulating film agent for a textured chromium-free electrical steel sheet is characterized in that the above hydroxide, oxide, carbonate, silicate or molybdate Fe, Ni, Co, Cu, Sr and Mo are a colloidal substance, stable as an aqueous solution .

(8) An insulating film agent for a textured chromium-free electrical steel sheet is characterized in that the colloidal substance is in the form of a single colloidal compound, a composite colloid of SiO ₂ or Al ₂ O ₃ or the like, or a mixture thereof.

(9) An insulating film agent for a textured chromium-free electrical steel sheet is characterized in that the colloidal substance has a grain size of 500 nm or less.

Brief Description of the Drawings

Figure 1 A, figure 1 B and figure 1 C are illustrations showing the method and results of evaluating the resistance of the film to annealing during annealing with stress relieving.

Figure 2 is an illustration showing the results of the assessment of setting during annealing with stress relieving in the case of adding and mixing with colloidal iron hydroxide (grain size 10 nm).

The best embodiment of the invention

The present invention describes a chromium-free composition in a conventional stretch type of insulating film, mainly containing a phosphate or phosphate element and colloidal silicon dioxide and a chromium compound. The film composition also eliminates defects in traditional compositions, of which chromium is excluded and which mainly contain phosphate or phosphate and silicon dioxide, i.e. hygroscopicity (stickiness and rusting) after drying of the film and a decrease in film tension due to setting after annealing with stress relieving and porosity films. As a result, by adding inorganic compounds Fe, Ni, Co, Cu, Sr and Mo to the component of the tension type film, mainly containing phosphate and phosphate and colloidal silicon dioxide, with elements from 0.06 to 2.10 mol. % relative to 1 mole of phosphate. The problem was solved in the traditional exclusion of chromium and the goal was achieved in terminating the insulating film agent with excellent corrosion resistance, annealing resistance, adhesion, sliding, insulation and the like, and excellent magnetic and magnetostrictive properties and processing method. It should be noted that in the present invention, “1 mol of phosphate” and “1 mol of primary phosphate” means 1 mol in the case of considering cations forming pairs with PO ₄ ^3- , НРО ₄ ^2- and Н ₂ РО ^4- (including not only ions metals, but also ammonium ions and the like) as a standard.

In the present invention, a textured electrical steel sheet finally processed by annealing is used as a starting material. Excess annealing release agent is removed, the sheet is lightly etched, then the surface of the steel sheet is coated with an insulating film solution and the sheet is dried.

The insulating film of the present invention is primarily characterized by the composition of the insulating film of the product.

First, the present invention is applied when the main ingredient is phosphate only and when phosphate and colloidal silicon dioxide are the main ingredients. In particular, the latter case where phosphate and colloidal silicon dioxide are the main ingredients in a chromium-free composition, the film structure after drying is porous. The hygroscopicity and setting during annealing are increased and a decrease in film tension is detected, so that a very large improvement effect can be obtained. If the content of colloidal silicon dioxide is less than 35 parts by weight, the film surface becomes white and opaque and a film with transparency and gloss cannot be obtained, the film tension effect is lost, and good magnetism and the effect of improving magnetostriction cannot be obtained. On the other hand, with a content of more than 100 parts by mass, when the hygroscopic stability and annealing resistance are improved, the effect of film tension is lost.

When using phosphate, primary phosphate is preferred. In particular, primary phosphates of Al, Mg, Ca, Ni and Co are preferred.

The insulating film of a product of textured electrical steel sheet is characterized by an insulating film agent having an insulating film containing from 0.06 to 2.10 moles of one or more compounds of Fe, Ni, Co, Cu, Sr and Mo as the corresponding metal elements relative to one mole of phosphate . Inventors engaged in extensive research and experiments on compounds exhibiting a Cr substituting effect, and as a result have discovered that the compounds Fe, Ni, Co, Cu, Sr and Mo are effective in filling the porous structure of phosphate and easily bind to free phosphoric acid to effect stabilizing phosphoric acid, in particular that the Fe compound exhibits an extremely excellent effect.

If the content of Fe, Ni, Co, Cu, Sr, and Mo compounds is less than 0.06 mol as the corresponding metal elements with respect to 1 mole of phosphate, the effects of filling the porous structure in the phosphate film and suppressing hygroscopicity and setting during annealing are insufficient. When the content is greater than 2.10 mol, the effects of improvement and film tension become extreme. A preferred range of these metal elements is from 0.5 to 1.5 mol.

In the case of a compound of Fe, Ni, Co, Cu, Sr and Mo in the film components, one or more hydroxide, oxide, carbonate, silicate and molybdate are added. In the case of adding hydroxide, oxide, carbonate, silicate and molybdate or the like, the filling action occurs during the drying of the insulating film, and the effect of fixing free phosphates occurs during drying and during the annealing with stress relieving. The best results were obtained with the addition of hydroxide. Hydroxide is easily destroyed during drying or annealing with stress relief, fills the film and reacts with the free components of phosphate, stabilizing them.

Then, in the case of an aqueous solution of hydroxide, oxide, carbonate, silicate or molybdate of Fe, Ni, Co, Cu, Sr and Mo or the like, an improvement effect can be obtained when a colloidal substance is applied. In the case of a colloidal solution, a solution of the siloxane structure is obtained in the case of colloidal silicon dioxide and a solution having excellent dispersion and stability of the solution is obtained using fine particles. In the case of mixing these colloidal substances, an extremely homogeneous dispersion forms in the above stock solution; during drying, an extremely excellent effect is observed when filling and stabilizing free phosphates.

In the case of a colloidal substance, there are methods for adding solutions of single colloidal substances or solutions of composite colloidal substances coated only on surface particles of SiO ₂ or Al ₂ O ₃ . Good results can be obtained in both cases. In the case of this type of colloidal substance, both the method of adding single colloidal substances of hydroxides, oxides, carbonates, silicates, molybdates and the like, and the method of composite colloidal substances with SiO ₂ or Al ₂ O _{3 can be used} . In the case of the colloidal substance of the present invention, the most outstanding effect is obtained in the case of hydroxides, in particular colloidal Fe hydroxide.

In the case of a colloidal substance, when the grain size is 500 nm or less, an excellent effect of filling the film and stabilizing free phosphates is obtained. In particular, when the size is 50 nm or less, more preferably 15 nm or less, an outstanding superior improvement effect is obtained compared to a crystalline compound prepared in a conventional wet manner.

The treatment agent prepared in this way is coated with a solid line using a coating roller while controlling the amount of coating, and dried after coating at 350 ° C. or higher. The amount of coating depends on the thickness of the steel sheet used and on the purpose of the product. If the film agent is from 2 to 10 g / m ² , a textured electrical steel sheet is obtained having excellent film performance and appearance, of course, magnetic and magnetostrictive properties.

The coating and drying conditions of the insulating film agent are not limited, but a coating and coating roller is preferably used, which is then dried at a temperature of 350 ° C. or higher. If the drying temperature is below 350 ° C, the reaction with the hydroxide, oxide, carbonate, silicate and molybdate of Fe, Ni, Co, Cu, Sr and Mo added to the primary phosphate does not proceed sufficiently, which reduces the properties of the film. When processing the product in order to separate the areas with a laser, with the effect of improving the magnetic properties, a temperature range from 350 ° C to 450 ° C is preferred. However, in order to exploit the difference in thermal expansion during drying as in a conventional textured electrical steel sheet to obtain a sufficient tension effect, corrosion resistance, and annealing resistance, drying at 750-900 ° C is necessary. The drying temperature is preferably 800 ° C or higher, more preferably 830 ° C or higher.

The hydroxide, oxide, carbonate, silicate and molybdate of Fe, Ni, Co, Cu, Sr and Mo and the like, uniformly distributed in the solution, are destroyed during the drying process and fill in the porous defects that arise in the case of only phosphate or phosphate and colloidal silicon dioxide. Strong, stable phosphate compounds are also formed, whereby the effect of improving film compaction, preventing hygroscopicity and film tension can be realized. In particular, this improvement effect is large in the case of the colloidal shape of the finely divided grains, possibly due to the aforementioned increase and homogenization of the reaction zone.

During the application of the agent of the present invention containing materials that do not form a glass film upon final annealing, a steel sheet is obtained in which the formation of glass is prevented. In this case, an annealing release agent or the so-called “glass-free materials” are used, from which the glass film has been removed by etching.

Example 1

Samples are cut from a winding of a textured electrical steel sheet with a high magnetic flux density, with a sheet thickness of 0.23 mm, containing a steel sheet, after finishing processing having a glass film on its surface, washed with water, then subjected to stress annealing at 850 ° C within 4 hours. Then the samples were slightly etched in an aqueous solution of 2% H ₂ SO ₄ at 85 ° C for 15 seconds, then coated with treatment agents, which vary depending on the addition of Fe, Ni, Co and Sr compounds, as shown in Table 1, c using a coating roller, the mass after drying is 5 g / m ² and dried at 850 ° C for 30 seconds. After that, the samples are cut from the sheets of the product and examined for the properties of the film. The results are shown in table 2.

It should be noted that “resistance to annealing” in table 2 means the value obtained by applying cut samples of the product sheet, as in FIG. 1A, fixing the stack as 1B, then annealing it at 850 ° C for 4 hours (in N ₂ , dew point 10 ° C), then by measuring the peeling force of the product sheet with a spring balance, as in FIG.

Table 1 50% primary phosphate ^{(* 1)} 20% colloidal silicon dioxide (size: 7 nm) Additives (number of moles per 1 mole of phosphate) Example 1 Mg phosphate (25 ml) + Al phosphate (25 ml) 100 ss Iron hydroxide, 0.15 Example 2 “ “ ", 1.00 Example 3 “ “ Nickel hydroxide, 1.00 Example 4 “ “ Strontium Carbonate 1.00 Example 5 “ “ Cobalt oxide, 1.00 Example 6 “ “ Sodium Molybdate 1.00 Comp. Example 1 “ “ Iron hydroxide, 0.05 Comp. Example 2 “ “ Iron hydroxide, 5.00 Comp. Example 3 “ “ No additives Compare example 4 50 cc Al phosphate +120 cc 20% colloidal silicon dioxide (5 nm) +6 g CrO ₃ (Japanese Patent Publication (A) No. 61-41778) (* 1) 25 ml of 50 wt.% Solutions of Mg phosphate: MgO and H ₃ PO ₄ mixed in a molar ratio of 0.45: 1, and phosphate A1: Al ₂ O ₃ and H ₃ PO ₄ mixed in a molar ratio of 0 , 16: 1, and mixed in equal amounts

table 2 Adhesion ^{(* 2)} Corrosion Resistance ^{(* 3)} Resistance to annealing (g / 9 cm ² ) Film tension (kg / mm ² ) Magnetic properties B ₈ (T) W _17/50 (w / kg) Etc. one Very good: no peeling Very good: no rust, good 150 0.80 1.93 0.83 Etc. 2 Very good: " Very good: no rust, good twenty 0.85 1.94 0.80 Etc. 3 Very good: " Very good: no rust, good one hundred 0.80 1.94 0.83 Etc. four Very good: " Very good: no rust, good 130 0.79 1.93 0.83 Etc. 5 Very good: " Good: slight rust 170 0.75 1.94 0.84 Etc. 6 Very good: " Very good: no rust, good 120 0.78 1.94 0.83 Wed pr. 1 Very good: " Very good: no rust, good 80 0.70 1.93 0.86 Wed pr. 2 Good: some peeling Good: slight rust thirty 0.68 1.93 0.86 Wed pr 3 Good: some peeling Medium: rust on a mostly clean surface 950 0.55 1.93 0.88 Wed pr 4 Very good: " Very good: no rust, good 70 0.82 1.93 0.83 (* 2) The insulating film is dried, then bent 20 mmF and express the estimated adhesion (* 3) Assessment of rust after 24 hours at 50 ° C and a humidity of 98% or more in the atmosphere

As a result of these experiments, when adding the compounds Fe, Ni, Co, SR, and Mo of the present invention, the hygroscopicity and resistance to annealing of the film after drying were significantly improved compared to the examples of non-addition of additives, and film properties were obtained that did not differ from comparative example 4 containing the traditional compound chromium. In particular, the effect of improving the characteristics of the film can be obtained by adding the compound Fe. However, when the amount of added iron hydroxide is small, the effect is weak, while if it is excessive, solution stability, corrosion resistance, film tension, etc. bad, that is, the characteristics of the film are bad.

Example 2

Samples are cut from the winding of a textured electrical steel sheet with a high magnetic flux density, with a sheet thickness of 0.23 mm, as in example 1, washed with water, then subjected to stress annealing at 850 ° C for 4 hours. Then the samples were slightly etched in an aqueous solution of 2% H ₂ SO ₄ at 75 ° C for 15 seconds. The steel sheets are coated with processing agents containing solutions that vary depending on the grain size of the colloidal solutions of Fe and Ni hydroxides, as additives, as shown in Table 3, using a coating roller, the mass after drying is 5 g / m ² , and dried at 850 ° C for 30 seconds. After that, the samples are cut from the sheets of the product and examined for the properties of the film. The results are shown in table 4.

Table 3 50% primary phosphate ^{(* 1)} 20% colloidal silicon dioxide (size: 7 nm) Additives (number of moles per 1 mole of phosphate) Example 7 Mg phosphate (25 ml) + Al phosphate (25 ml) 100 ss Iron hydroxide (10 nm), 0.15 Example 8 “ “ Iron hydroxide (10 nm), 0.50 Example 9 “ “ Iron hydroxide (10 nm), 1.25 Example 10 “ “ SiO ₂ - Iron hydroxide (10 nm) ^{(* 4)} , 0.25 Example 11 “ “ SiO ₂ - Iron hydroxide (10 nm), 0.50 Example 12 “ “ SiO ₂ - Iron hydroxide (800 nm), 0.50 Example 13 “ “ Nickel hydroxide (10 nm), 0.50 Example 14 “ “ Nickel hydroxide (10 nm), 1.25 Example 15 Iron hydroxide (350 nm), 1.25 Example 16 Nickel hydroxide (500 nm), 1.25 Compare example 5 No additives Comp. Example 6 50 cc Al phosphate +120 cc 20% colloidal silicon dioxide (5 nm) +6 g CrO ₃ (Japanese Patent Publication (A) No. 61-41778) (* 4) Composite colloidal solution of SiO ₂ , on the surface of which iron hydroxide is formed by a mass ratio of 3: 1 The numbers in () indicate the grain size of the composite

Table 4 Adhesion ^{(* 2)} Corrosion Resistance ^{(* 3)} Resistance to annealing (g / 9 cm ² ) Film tension (kg / mm ² ) Magnetic properties B ₈ (T) W _17/50 (w / kg) Example 7 Very good: no peeling Good: slight rust 80 0.81 1.94 0.82 Example 8 Very good: " Very good: no rust, good thirty 0.84 1.93 0.80 Example 9 Very good: " Good: slight rust 10 0.82 1.94 0.79 Etc. 10 Very good: no peeling Very good: no rust, good 90 0.81 1.94 0.81 Example 11 Very good: " Very good: no rust, good 10 0.85 1.94 0.78 Example 12 Very good: " Very good: no rust, good one hundred 0.78 1.93 0.84 Example 13 Very good: " Very good: no rust, good 40 0.80 1.93 0.83 Example 14 Very good: " Very good: no rust, good twenty 0.78 1.94 0.84 Example 15 Good: some peeling Medium: rust on a mostly clean surface 350 0.75 1.93 0.85 Example 16 Very good: " Very good: no rust, good 400 0.72 1.93 0.86 Compare example 5 Good: some peeling Medium: rust on a mostly clean surface 1000 0.56 1.93 0.87 Comp. Example 6 Very good: " Very good: no rust, good 90 0.80 1.94 0.82

As a result of these experiments, in the case of adding the compound obtained by preparing the Fe and Ni hydroxides of the present invention as a colloidal solution, a significant effect of improving corrosion resistance and annealing resistance can be obtained. Compared to the example of incorporation of a traditional chromium compound, films with a magnetic property are obtained. Also, when using a composite colloidal substance prepared from SiO ₂ , on the surface of which iron hydroxide is provided as a composite substance as a colloidal substance, the same effect is obtained by adding a single colloidal substance. In contrast to this, in the non-addition example of the colloidal solution of the inorganic compound of comparative example 5, as in example 1, the result of corrosion resistance and annealing resistance was extremely low. Also, in the case of adding a colloid with a large grain size of colloidal substances, as in examples 12, 15 and 16, although the improvement effect can be seen, but it is not significant.

Example 3

The same experimental procedure as in Example 2 is used to measure annealing resistance when the amount of addition of colloidal iron hydroxide solution (10 nm) is changed relative to 100 ml of a primary solution of primary phosphate Al; 25 ml + primary phosphate Mg; 25 ml + 20% colloidal silicon dioxide (7 nm) in a molar ratio relative to phosphate from 0 to 2.5. The results are shown in FIG. By adding 0.06 mol or more of iron hydroxide per 1 mol of phosphate, the peeling force can be significantly reduced.

Industrial applicability

According to the present invention, by adding the compounds of hydroxides, oxides, carbonates, silicates and molybdates of Fe, Ni, Co, Cu, Sr, Mo to a phosphate-based tension film not containing a chromium compound, the corrosion resistance of the film after drying is improved and can be obtained significant effect of improving setting resistance during annealing with stress relieving. In particular, a significant effect is observed upon the addition of a finely divided colloidal substance Fe.

Claims (5)

1. Textured electrical steel sheet having an insulating film that does not contain chromium, characterized in that the insulating film contains phosphate and one or more colloidal substances selected from inorganic compounds Fe, Ni, Co, Cu, Sr and Mo containing metal elements from 0.06 to 2.10 mol per mol of this phosphate calculated on metal ions and having grain sizes of colloidal substances Fe, Ni, Co, Cu, Sr and Mo of 50 nm or less. 2. Textured electrical steel sheet according to claim 1, characterized in that the insulating film contains from 35 to 100 wt. including SiO ₂ relative to 100 wt. including phosphate. 3. An insulating film for textured electrical steel sheet that does not contain chromium, which contains phosphate and one or more colloidal substances Fe, Ni, Co, Cu, Sr and Mo, containing metal elements from 0.06 to 2.10 mol per mol of one or more types of primary phosphates selected from Al, Mg, Ca, Ni and Co, calculated on metal ions and having a grain size of colloidal substances Fe, Ni, Co, Cu, Sr and Mo of 50 nm or less. 4. The insulating film according to claim 3, characterized in that it contains colloidal silicon dioxide in the equivalent of a solid substance from 35 to 100 wt. hours relative to 100 wt. including specified phosphate. 5. The insulating film according to claim 3 or 4, characterized in that the colloidal substance has the form of a single colloidal compound, a composite colloid SiO ₂ or
Al ₂ O ₃ or mixtures thereof.

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