JP3276567B2 - Insulating coating agent having excellent coating characteristics and method for producing grain-oriented electrical steel sheet using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain-oriented electrical steel sheet insulating coating agent for improving the coating properties such as tension imparting properties, insulation properties and adhesion, and magnetic properties, and a directionality with excellent coating properties using the same. The present invention relates to a method for manufacturing an electromagnetic steel sheet.

[0002]

2. Description of the Related Art Grain-oriented electrical steel sheets, for example, contain
% Of the slab is hot-rolled, annealed and then cold rolled once or twice with annealing to obtain a final sheet thickness, then decarburized annealing to perform primary recrystallization and an oxide layer mainly composed of SiO _{2 on the} steel sheet surface. After formation, an annealing separator containing MgO as a main component is applied, and a final finish annealing is applied to develop secondary recrystallization having a Goss orientation and remove impurities such as S and N, and at the same time, to form a glass film. Do. Next, a coating agent for an insulating film is applied, and baking and heat flattening are simultaneously performed to obtain a final product.

[0003] The grain-oriented electrical steel sheet thus obtained is mainly used as an iron core material for electrical equipment and transformers, and is required to have a high magnetic flux density and a low iron loss value. Further, when the grain-oriented electrical steel sheet is used as a transformer core, in the case of a wound core, the hoop slit into a predetermined size is cut and wound while being continuously unwound at a high speed.
After performing winding work called lacing through compression molding and strain relief annealing, it is put into a case and made into a transformer. In the case of a stacked iron core, the slit hoop is cut into a predetermined size, then, if necessary, is subjected to strain relief annealing, and is wound to perform a winding operation to obtain an iron core. In this iron core processing step, for example, in the case of a wound iron core, high-speed continuous processing can be performed smoothly, and the core after molding does not have irregularities on the end face or the lap portion, and it is important that the shape is excellent, For this purpose, it is important that the surface of the steel sheet has excellent slipperiness and scratch resistance. In addition, it is important that there is no seizure between the steel sheet coatings during the annealing and that the lacing operation can be performed easily from the viewpoint of improving the core processing efficiency and preventing deterioration of the coating performance and magnetic properties.

[0004] Since the properties of the insulating film of the grain-oriented electrical steel sheet greatly affect these problems, high tensile strength, which is excellent in winding workability, heat resistance, and adhesion, and excellent in improving iron loss, magnetostriction, and the like. There is a strong demand for the development of insulating films. As a means for improving the workability of the transformer core and the magnetic properties, an application material for forming an insulating film has been improved. Japanese Patent Application Laid-Open No. 61-41778 discloses that as a coating agent, a primary phosphate such as Mg or Al and ultrafine colloidal silica having a particle diameter of 8 nm or less are used as main components, and one or two types of chromate or chromate are used. A technique has been disclosed in which a mixed liquid composed of at least one kind is applied to a steel sheet after finish annealing and baked to improve the slipperiness of an insulating film formed on the surface of the steel sheet. Japanese Patent Application Laid-Open No. 7-180064 discloses a new technique by the present inventors, such as M 2 ⁺ _{1 -X} M ³⁺ (O
_{H) 2 + X-ny Ay} n- · mH 2 O in formula average particle size 1μm or less of the solid solution type composite metal hydroxide composition represented by a directional electromagnetic steel sheet for coating have been proposed. The former achieves an improvement in slipperiness and an improvement in seizure resistance by smoothing the film surface with ultrafine colloidal silica and improving the fixing ability of free phosphoric acid by increasing the particle surface area. The latter shows that the new film composition having no Cr compound has a film tension superior to that of the conventional phosphate and colloidal silica main component film and excellent film adhesion.

[0005]

In these prior arts, in the former case, the film tension is determined by the compounding ratio of the primary phosphate and the colloidal silica, and its improvement is limited, and the adhesion of the film is limited. Further, it is desired to further improve the seizure property during strain relief annealing. In the latter, since a large amount of boric acid or phosphoric acid is required as an anion substance or an additive in the film forming reaction, it is necessary to improve seizure resistance during annealing, moisture absorption, and the like. It is desired to further improve the film-forming ability in order to improve corrosion resistance, surface smoothness, and heat resistance in strain relief annealing.

[0006]

SUMMARY OF THE INVENTION The present inventors have found that an insulating film containing a composite metal hydroxide as a main component as described above requires a considerable amount of an anionic substance and an additive for vitrification of the film. The improvement of the liquid composition, the improvement of the liquid production conditions, and the baking conditions were examined. As a result, 2
By compounding a fixed amount of a monovalent metal hydroxide with a monovalent and trivalent composite metal hydroxide, the ability of the insulating coating to form a film is significantly improved. As a result, it has been found that the compounding ratio of boric acid, phosphoric acid, etc., which is a film forming aid, is suppressed, and that an insulating film having good surface properties and film performance can be obtained at a lower temperature and in a shorter time even during baking treatment. Was completed.

That is, the present invention provides the following (1) and (2). _{^{(1) M 2+ 1-X}} M 1+ x1 M 3+ x2 (OH) 2 + X-ny A ny · m
An insulating film agent for grain-oriented electrical steel sheets having excellent film properties, characterized by having a solid solution type composite metal hydroxide composition represented by the general formula of H ₂ O. _{^{(2) M 2+ 1-X}} M 1+ x1 M 3+ x2 (OH) 2 + X-ny A ny · m
Solid solution composite metal hydroxide 10 represented by the general formula of H ₂ O
An insulating coating agent in which 10 to 500 parts by weight of one or more of boric acid, phosphoric acid, silicic acid, chromic acid, borate, silicate, chromate, hydroxide, and oxide is added to 0 part by weight. .

(3) M 2 ⁺ _{1 -X} M ¹⁺ _x1 M ³⁺ _x2 (OH)
To _{^{2 + X-ny A ny ·}} mH 2 Formula solid solution type composite metal hydroxide 100 parts by weight represented by the O, boric acid, phosphoric acid, silicic acid,
Apply an insulating coating agent aqueous solution containing 10 to 500 parts by weight of one or more of chromic acid, borate, silicate, chromate, hydroxide, and oxide to the steel sheet surface after the final finish annealing. A method for producing a grain-oriented electrical steel sheet having excellent film properties, comprising baking at 600 to 1000 ° C.

However, M ¹⁺ ; monovalent metal such as Li, K, Na, etc. M ²⁺ ; Be, Mg, Ca, Ba, Sr, Sn, Mn, F
e, Co, Ni, Cu, Zn, and other divalent metals M ³⁺ ; Al, Fe, Cr, Co, Sb, Bi, In,
B, Ga, 3-valent metals such as Ti ^{A n-; OH -, F -} , Cl -, Br -, CO 3 2-, SO
_{^{4 2-, SiO 3 2 -,}} HPO 4 2-, CrO 4 2-, (CH 3
^{COO) -, Fe (CN)} 6 3-, BO 3 n -valent anion of ^3-like X = x1 + x2, 0 < X <1.0, 0 <y <2.
0, m; number of molecules of interlayer water

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The types of the inorganic compounds used in the present invention are as follows. In the present invention, a composite hydroxide composed of a divalent metal element, a trivalent metal element and a monovalent metal element is applied and baked on a steel sheet as a sol-like aqueous solution. The form of the ^{_{hydroxide, M 2+ 1- X M 1+ x1}} M 3+ x2 (OH) 2 + X-ny A ny
· MH represented by ₂ O. Basic composition M ²⁺ _1-X M ¹⁺ _x1 M ³⁺ _x2
The divalent metal element applied to (OH) _{2 + X-ny} is Be, M
g, Ca, Ba, Sr, Sn, Mn, Fe, Co, N
i, Cu, Zn, etc., and trivalent metals such as Al, F
e, Cr, Co, Sb, Bi, In, B, Ga, and Ti, and monovalent metals for promoting the reaction include Li, N
a, K, etc.

The crystal structure thus obtained is a layered structure composed of two types of layers, a positively charged basic layer similar to brucite, and a negatively charged intermediate layer composed of anions and interlayer water. These include those in which monovalent and divalent hydroxides are simultaneously dissolved in a trivalent hydroxide. Examples of such a substance include a trivalent hydroxide in which monovalent and divalent hydroxides are dissolved, and a divalent hydroxide in which monovalent and trivalent hydroxides are dissolved. Or both of them are used. In these solid-solution type composite hydroxide substances, the effects of the anion substance and interlayer water act synergistically mainly due to solid solution, and secondarily, a high reaction which cannot be obtained with a simple hydroxide substance. And low melting point. At this time, the composite of the monovalent metal hydroxide further increases the effect of lowering the melting point. For this reason, compared with the case of divalent and trivalent composite hydroxides, there is an effect that the amount of additives such as an anionic substance and boric acid can be reduced. Further, a high-strength film having excellent surface properties can be formed stably even at a low temperature and short-time baking condition.

[0012] In addition, these coating agents can arbitrarily select a coating material having a low thermal expansion coefficient and a high elongation characteristic, which are important for the development of tension as compared with the conventional phosphate-colloidal silica-chromate coating. There are advantages. Therefore, an insulating film having a higher tensile strength can be formed as compared with a conventional film agent. The composition of the treating agent used in the present invention is as follows.

In the present invention, when a composite hydroxide of a monovalent, divalent or trivalent metal is used as a basic component of the insulating coating agent, a monovalent metal contained in a certain amount and an anionic group in the hydroxide structure thereof are contained. Thereby, a remarkable effect of lowering the melting point can be obtained. In addition, when boric acid, phosphoric acid, or the like is used as an additive, the presence of the monovalent alkali metal element reacts at the time of baking, has an effect of stably fixing them, and improves heat resistance and moisture absorption. Furthermore,
Although the reason is not clear, when a monovalent metal is contained in the composite hydroxide, surface oxidation in the baking process tends to be suppressed. The amount of the monovalent metal hydroxide is not particularly limited, but is preferably 20% or less as a proportion of the total hydroxide. This is because there is a limit to the solid solution, and if the ratio of the hydroxide of the monovalent metal is too large, the corrosion resistance of the film is lowered or the film tension is lowered depending on the conditions of the baking treatment. .

The anionic substance in the composite hydroxide structure has the effect of lowering the melting point and, when added with another reaction accelerator such as boric acid, has the property of being easily replaced and stably incorporated into the structure. It also acts to stabilize additives. For this composite hydroxide, for the purpose of further improving the adhesion and facilitating the film formation industrially, boric acid, phosphoric acid, silicic acid, chromic acid,
One or more of borate, phosphate, silicate, chromate, hydroxide, and oxide may be blended in an amount of 10 to 500 parts by weight based on 100 parts by weight of the composite hydroxide material. desirable. Addition of these compounds further promotes lowering the temperature and shortening the time of the insulating film forming reaction. Further, the sealing property of the film is improved, the oxidation of the steel sheet surface during the film formation is suppressed, and the adhesion is improved. The mixing ratio of these additives is 10
If the amount is less than parts by weight, such an effect becomes extremely small.
On the other hand, if it exceeds 500 parts by weight, the film tension may decrease, or the surface of the film may become sticky or heat-resistant due to hygroscopicity due to excessive boric acid, phosphoric acid, silicic acid, chromate, borate, phosphate, silicate, chromate, etc. And the seizure during strain relief annealing occur.

As a method of applying and baking a processing solution, a processing agent is diluted to an appropriate concentration with water in a continuous line, applied in a predetermined amount by a roll coater, and then subjected to baking at 600 to 1000 ° C. for a short time. If the baking temperature is lower than 600 ° C., it takes time to vitrify the composite hydroxide,
There is a problem in industrial use. Also, the thermal expansion of the steel sheet during baking is insufficient, and the film tension is reduced. On the other hand, 1000
If the temperature exceeds ℃, it is difficult to control the elongation of the steel sheet during baking in a continuous furnace. In consideration of the development of tension and productivity, the most preferable conditions are 750 to 95.
0 ° C.

The treating agent of the present invention is applied to a grain-oriented electrical steel sheet subjected to final annealing. In this case, there are four cases. First, when applied on the glass film after final annealing,
The second is to apply the product to the glass film with another insulating film applied and baked, the third is to apply the insulating film agent of the present invention and then apply another insulating film agent after baking, and the fourth is finishing The treatment agent of the present invention is applied and baked after suppressing the formation of a glass film during annealing or removing the surface film by pickling or the like after finish annealing. In these various cases, it is preferable to perform light acid washing as a preliminary treatment before the insulating film treatment or to sufficiently coat with water and then apply the coating in order to obtain uniform coatability. Depending on these applications, the film is formed by controlling the amount of the film agent applied, the tension in the baking furnace of the steel sheet, the heat cycle, and the like.

In the present invention, monovalent,
A composite hydroxide of fine particles made of a divalent or trivalent metal element and boric acid, phosphoric acid, silicic acid,
By adding chromic acid and / or their metal salts, hydroxides, oxides, etc., an insulating film is formed by baking at 600 to 1000 ° C. for a short time. At this time, the composite of the monovalent metal hydroxide plays a large role in forming the film at a low temperature in a short time, making it uniform, and stabilizing the surface properties. The insulating film thus obtained is dense and excellent in corrosion resistance, adhesion, insulation, heat resistance, space factor and the like. Furthermore, in the present invention, depending on the selection of additives, it is possible to use a composition that does not use phosphoric acid or a chromium compound, which has been used as a main component of a conventional insulating film, so that the film can be removed in the iron core processing step. A film can be formed without any problem of working environment contamination.

Another advantage of the composite hydroxide main component film of the present invention is the stabilization of anionic substances and additives. The composite hydroxide has such a property that these anionic substances and additive substances can be easily incorporated into the film structure, so that the hygroscopicity of the additives and the fusion property in strain relief annealing can be extremely reduced.

[0019]

【Example】

<Example 1> A slab of a high magnetic flux density grain-oriented electrical steel sheet was treated by a known method by hot rolling, hot-rolled sheet annealing, pickling, and cold rolling to obtain a cold-rolled sheet having a final sheet thickness of 0.225 mm. This coil,
N ₂ 25% + H ₂ 75%, dew point 840 in an atmosphere of 65 ° C.
Decarburization annealing was performed at 120C for 120 seconds. Then, Mg01
After applying and drying an annealing separator having a composition of 00 parts by weight, 5 parts by weight of TiO _{2 and} 0.3 parts by weight of sodium borate, 1200 ° C.
The final finish annealing of × 20Hr was performed, secondary recrystallization, purification and glass film formation were performed, and used as a starting material.

The coil is washed with water to remove excess Mg on the surface.
O was removed, and after 2% H ₂ SO ₄ , light pickling at a liquid temperature of 80 ° C. for 10 seconds, an aqueous solution in which boric acid was blended with the composite hydroxide and the main component sol of the anionic substance in Table 1 Was applied so that the weight after baking was 3 g / m ² , dried in a continuous furnace, and treated at 850 ° C. for 30 seconds. Table 2 shows the film properties and magnetic properties in this test.

[0021]

[Table 1]

[0022]

[Table 2]

As a result, all of the films according to the present invention formed a high-tensile, glossy and transparent glass film, the film surface was smooth, and the adhesion was good. On the other hand, the composite hydroxide sol of Comparative Example 2 containing no monovalent metal hydroxide
In the case of a composite hydroxide of a trivalent metal and a trivalent metal, there was a tendency that the vitrification was slightly insufficient, the gloss was slightly dull, and the adhesion and the film tension were slightly inferior to those of the film of the present invention.
In addition, the comparative material using phosphate-colloidal silica resulted in significantly worse results than the present invention in terms of adhesion positiveness, film tension, and magnetism.

Example 2 C in weight%; 0.050%,
Si: 3.35%, Mn: 0.11%, Al: 0.03
125% of a slab containing 3%, S: 0.007%, and N: 0.0075%, with the balance being iron and unavoidable impurities.
After heating at 0 ° C., hot rolling, hot-rolled sheet annealing, pickling, and cold rolling were performed by known methods to give a final sheet thickness of 0.22 mm. Then
840 ° C. × 120 seconds, N ₂ 25% + H as atmosphere gas
₂ 75% dew point After decarburizing annealing at 60 ° C, N ₂ 25% + H ₂ 75
Nitriding treatment was performed in% NH ₃ so that the N content in the steel was 210 ppm. 100% by weight of Mg0 + BiCl3
3% annealing separator is applied, 1200 ° C x 20
A final annealing of Hr was performed to produce a high magnetic flux density oriented electrical steel sheet material without a glass coating.

This steel sheet was prepared by adding 2% of H ₂ SO ₄ and a liquid temperature of 80 ° C. ×
After 15 seconds of light pickling, monovalent, 2-valent as shown in Table 3
A treating agent in which boric acid was blended with a complex oxide composed of a trivalent metal and trivalent metal was applied so as to have a weight of 5.0 g / m ² after baking, followed by baking at 850 ° C. for 30 seconds. Next, the sample was taken out, irradiated with laser at intervals of 5 mm in a direction perpendicular to the rolling direction, and subjected to magnetic domain refining treatment to evaluate magnetic properties and film properties. Table 4 shows the results.

[0026]

[Table 3]

[0027]

[Table 4]

As a result of this test, any of the composite hydroxides containing the monovalent metal hydroxide of the present invention had excellent surface properties such as gloss, transparency and surface roughness of the film, and The adhesion and film tension were extremely excellent, and the magnetic properties were also good. On the other hand, in the case of the composite hydroxide composed of only divalent and trivalent metals of the comparative example, the film characteristics were considerably inferior to those of the present invention, and the magnetic characteristics tended to be slightly inferior as in the examples.
Further, in the case of the coating film made of phosphate-colloidal silica, the results were inferior to those of the present invention in terms of adhesion, coating tension, and magnetic properties.

[0029]

According to the present invention, a grain-oriented electrical steel sheet having an insulating film having good surface properties, high tension and excellent adhesion can be produced.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Osamu Tanaka 59 Nippon Steel Plant Design Co., Ltd., 46 Ohara Nakahara, Tobata-ku, Kitakyushu-shi, Fukuoka (56) Reference JP-A 8-35014 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) C23C 22/00-22/86

Claims (3)

(57) [Claims] 1. M ²⁺ _1-X M ¹⁺ _x1 M ³⁺ _x2 (OH) _{2 + X-ny} A
oriented electrical steel sheet insulating coating agent having excellent film properties, which is a solid solution-type composite metal hydroxide composition represented by the general formula ^n- _y · mH ₂ O. However, a monovalent metal selected from M ¹⁺ ; Li, K, and Na M ²⁺ ; Be, Mg, Ca, Ba, Sr, Sn, Mn, F
e, a divalent metal M ³⁺ selected from Co, Ni, Cu, Zn and the like; Al, Fe, Cr, Co, Sb, Bi, In,
B, Ga, 3-valent metal selected from among ^{Ti A n-; OH -, F} -, Cl -, Br -, CO 3 2-, SO
_{^{4 2-, SiO 3 2 -,}} HPO 4 2-, CrO 4 2-, (CH 3
^{COO) -, Fe (CN)} 6 3-, BO 3 n -valent anion of ^3-like X = x1 + x2, 0 < X <1.0, 0 <y <2.
0, m; number of molecules of interlayer water 2. M 2 ⁺ _{1 -X} M ¹⁺ _x1 M ³⁺ _x2 (OH) _{2 + X-ny} A
to _^n-y · mH ₂ Formula solid solution type composite metal hydroxide 100 parts by weight represented by the O, boric acid, phosphoric acid, silicic acid, chromic acid, borates, silicates, chromates, hydroxides And an insulating coating agent containing 10 to 500 parts by weight of one or more oxides. However, a monovalent metal selected from M ¹⁺ ; Li, K, and Na M ²⁺ ; Be, Mg, Ca, Ba, Sr, Sn, Mn, F
e, a divalent metal M ³⁺ selected from Co, Ni, Cu, Zn and the like; Al, Fe, Cr, Co, Sb, Bi, In,
B, Ga, 3-valent metal selected from among ^{Ti A n-; OH -, F} -, Cl -, Br -, CO 3 2-, SO
_{^{4 2-, SiO 3 2 -,}} HPO 4 2-, CrO 4 2-, (CH 3
^{COO) -, Fe (CN)} 6 3-, BO 3 n -valent anion of ^3-like X = x1 + x2, 0 < X <1.0, 0 <y <2.
0, m; number of molecules of interlayer water 3. M 2 ⁺ _{1 -X} M ¹⁺ _x1 M ³⁺ _x2 (OH) _{2 + X-ny} A
to _^n-y · mH ₂ Formula solid solution type composite metal hydroxide 100 parts by weight represented by the O, boric acid, phosphoric acid, silicic acid, chromic acid, borates, silicates, chromates, hydroxides A film characteristic characterized by applying an aqueous solution of an insulating coating agent containing 10 to 500 parts by weight of one or more oxides added to the steel sheet surface after the final annealing and baking at 600 to 1000 ° C. Manufacturing method of magnetic steel sheet with excellent direction. However, a monovalent metal selected from M ¹⁺ ; Li, K, and Na M ²⁺ ; Be, Mg, Ca, Ba, Sr, Sn, Mn, F
e, a divalent metal M ³⁺ selected from Co, Ni, Cu, Zn and the like; Al, Fe, Cr, Co, Sb, Bi, In,
B, Ga, 3-valent metal selected from among ^{Ti A n-; OH -, F} -, Cl -, Br -, CO 3 2-, SO
_{^{4 2-, SiO 3 2 -,}} HPO 4 2-, CrO 4 2-, (CH 3
^{COO) -, Fe (CN)} 6 3-, BO 3 n -valent anion of ^3-like X = x1 + x2, 0 < X <1.0, 0 <y <2.
0, m; number of molecules of interlayer water