JP3509475B2 - Non-oriented electrical steel sheet with insulating coating with excellent seizure resistance and slip resistance after strain relief annealing - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic material that exhibits excellent slip properties even when stress relief annealing is performed without the fusion of the steel sheets in stress relief annealing of a non-oriented electrical steel sheet cut or punched into a predetermined shape. -A non-oriented electrical steel sheet having an insulating coating of an organic mixed composition.

[0002]

2. Description of the Related Art Non-oriented electrical steel sheets used for iron cores of motors and electric equipment are formed by forming an electric insulation coating on the surface of the steel sheet, slitting it into a predetermined width, then punching it into an iron core shape, and then laminating it. The end face is fixed by TIG welding or caulking and assembled. Further, strain relief annealing may be performed at a temperature of 700 to 800 ° C. in order to remove iron loss deterioration due to work strain and improve the magnetic flux density by improving the crystal structure. Therefore, the insulating coating of the non-oriented electrical steel sheet is required to have many properties such as adhesion, corrosion resistance, punchability, weldability and heat resistance, as well as excellent electrical insulation. In addition, when there is a laminating operation after performing stress relief annealing like an EI iron core, it is important that the steel sheets do not fuse even if annealed and excellent in slipperiness.

Conventionally, insulating coatings of various compositions have been developed and improved in order to satisfy these required characteristics. Among them, it has been found that the punching property is remarkably improved by the use of an organic resin, and recently, a chromate, a phosphate, or an inorganic colloidal composition capable of forming a film at a low temperature as a main ingredient is used as a water-soluble resin or an emulsion. Insulating coatings of inorganic-organic mixed composition in which a resin is mixed are most often used.

However, since the insulating film of the above-mentioned mixed composition has a heat resistant temperature of about 400 ° C. of organic substances, it is 700 to 80 like the strain relief annealing in the consumer of electromagnetic steel sheets.
When annealed at a high temperature of 0 ° C., the organic substances in the coating are burned off and a porous coating structure is formed. Therefore, after annealing, important coating properties such as electrical insulation, corrosion resistance, and slip properties of the steel sheet as an insulating coating of the electromagnetic steel sheet are lost.

Although the inorganic-organic mixed coating obtained by adding the water-soluble resin or emulsion resin to the chromate salt, phosphate salt, or inorganic colloidal solution as described above is excellent in punching property of steel sheet, it is subjected to strain relief annealing. In this case, there is a fundamental problem that the coating properties are extremely deteriorated, and improvement of the coating has been strongly desired.

[0006]

As means for improving the annealing resistance of the above mixed coating, Japanese Patent Publication No. 55-1348 discloses phosphoric acid, chromic acid, boric acid, a water-soluble organic compound having a thio bond, and alum. There is disclosed a method of applying a treatment liquid mixed with the magnetic steel sheet. In addition, JP-A-5-
Japanese Patent No. 65663 discloses that a treatment liquid containing chromate and an emulsion resin as main components contains Si having a particle diameter of 1 to 30 μm.
An insulating coating treatment method is disclosed in which a colloidal inorganic substance such as O ₂ , Al ₂ O ₃ , TiO ₂ , and ZrO ₂ is added.
These prior arts utilize the heat resistance of the inorganic composition with respect to the annealing temperature. Although the seizure resistance and the deterioration of the electrical insulation due to the strain relief annealing can be prevented, the punchability is poor. or,
The slip property after the stress relief annealing was not expected.
Therefore, a method has been proposed in which a powder resin is added in order to improve punchability, weldability, and slipperiness.

For example, Japanese Patent Laid-Open No. 3-240970 discloses a chromate or phosphate aqueous solution in which a fine particle emulsion resin having a particle size of 0.2 to 0.5 μm and a coarse particle resin having a particle size of 1 to 50 μm are mixed. How to apply. JP-A-4-218
No. 677, a spherical resin powder having a particle diameter of 2 to 20 μm is added to an emulsion resin compounding treatment liquid containing a chromate as a main component, and a surface roughness of Ra = 0.3 to 0.5 μm is provided on the surface of the magnetic steel sheet. It is a method of treating an insulating film. In these methods, the coarse-grained resin on the coating surface remains as carbon fiber-like projections after annealing by adding the coarse-grained resin,
Although it is intended to prevent seizure of the steel sheet and improve the slip property, the carbon fiber-like projections on the coating surface have weak adhesion and are easily peeled off during the laminating work of the EI iron core. Therefore, the laminated EI piece has a problem that many scratches are generated on the surface of the coating film, and the electrical insulating property and the corrosion resistance are impaired.

As described above, in the prior art, there has been proposed a method of adding a new inorganic composition or a coarse-grained resin to an inorganic-organic mixed coating containing an organic composition. Of the electrical steel sheet and deterioration of the electrical insulation and corrosion resistance due to the occurrence of scratches after annealing and it did not satisfy the requirements of the manufacturers of electrical steel sheets. Therefore, the present invention, in the inorganic-organic mixed coating, has a coating excellent in seizure resistance during strain relief annealing and slip resistance during iron core processing, preventing the occurrence of the above coating defects without impairing the conventional coating performance. It is intended to provide a non-oriented electrical steel sheet.

[0009]

In order to prevent a coating defect newly generated by adding a coarse-grained resin, the inventors of the present invention adhere to the coating surface after annealing without deteriorating punchability. However, we considered that it would be effective to develop an additive that does not easily come off, and conducted various studies on the composition, morphology, and amount of additive. As a result, by adding a small amount of fine powder having the characteristics of inorganic substances and the properties of organic substances, which will be described in detail later, it has lubricity peculiar to organic resin in the punching process stage before annealing, and it is peculiar to inorganic substances after stress relief annealing. It has heat resistance, and the additive adheres to the film during the strain relief annealing process, without causing the occurrence of new film defects of electrical insulation and corrosion resistance, which were the drawbacks of the prior art, and it has seizure resistance. The inventors have found that the slip property is improved and have completed the present invention.

That is, the gist of the present invention is that an inorganic-organic mixed coating film containing at least one selected from chromic acid compounds and phosphoric acid compounds and an organic composition as a basic component has a film thickness of 0 after drying. 1 to 20% by weight of silicone resin of spherical monodisperse fine particles having an average particle diameter of 0.5 to 3.0 times
It is a non-oriented electrical steel sheet having a contained insulating coating.

Another aspect of the present invention is to use an inorganic-organic mixed coating containing an inorganic colloid composition and an organic composition as basic components without using chromic acid or a phosphoric acid compound as a main component, and to adjust the film thickness after drying. It is a non-oriented electrical steel sheet having an insulating coating containing 1 to 20% by weight of a spherical monodisperse fine particle silicone resin having an average particle diameter of 0.5 to 3.0 times. In any of the above cases, the thickness of the insulating coating after drying is 0.1 to 3.0 μm.
It is preferably within the range of m.

[0012]

[Action]

(Silicone resin used in the present invention) The feature of the present invention is that a non-oriented electrical steel sheet having an inorganic-organic mixed coating is punched into a predetermined shape, and then steel sheet produced in the process of strain relief annealing at a temperature of 700 to 800 ° C. In order to prevent deterioration of the slip property due to mutual fusion and resin thermal decomposition, spherical silicone resin fine particles having excellent heat resistance are contained in the coating film.

This silicone resin is ≡Si-O-Si≡
It has a three-dimensional network structure with a siloxane bond as a skeleton, and has the advantages of organic and inorganic substances such as excellent lubricity, heat resistance, and chemical resistance. Therefore, the coating film has improved lubricity, and the punchability of the steel sheet acts advantageously. Moreover, even when the treatment liquid is prepared, it is not altered or decomposed even if it is mixed with a strong acid such as chromate or phosphate, and the specific gravity is relatively smaller than that of the inorganic fine powder (SG1.3). Precipitation does not occur in the liquid and the liquid is easy to manage. The greatest feature is the heat resistance peculiar to siloxane, and the strain relief annealing temperature of 700-
It does not melt at a temperature of 800 ° C., and the weight loss is only about 10%. Therefore, even if strain relief annealing is applied, the silicone resin powder remains in the film as a sintered body of silica and is firmly bonded, so it does not peel off during the iron core lamination process after annealing, so it is not electrically isolated. It is possible to alleviate the drawbacks of conventional inorganic powder additions such as deterioration of corrosion resistance and deterioration of corrosion resistance and coating defects newly generated by addition of coarse-grain resin.

The silicone resin particles used in the present invention are spherical monodisperse type fine particles, have a comparatively smooth surface with no angular surface, and form uniform single particles instead of agglomerates. Is. In particular, a spherical shape is preferable in terms of punching property and slip property after annealing. The coating containing such fine particles of silicone resin has a surface shape with fine irregularities, and since the shape is maintained even after annealing, it is possible to prevent fusion of the steel sheets during the annealing process, and also to prevent slippage after annealing. Can be improved.

FIG. 1 shows a plate thickness of 0.
A finish plate of 5 mm non-oriented electrical steel sheet that has been subjected to finish annealing, to which spherical silicone resin powders having different particle diameters in the range of 0.3 to 45 μm are added, and the following treatment liquid is applied by a rubber roll to reach the plate. It was baked at a temperature of 300 ° C. The obtained film was subjected to strain relief annealing at 750 ° C. in dry (Dry) N ₂ , and then the slip property and the dust resistance were investigated by the method described later,
The values are shown for the particle size / film thickness of the silicone resin. The film thickness after coating and drying was 0.7 to 1.3 μm with respect to the target film thickness of 1.0 μm as the average film thickness of the portion where the silicone resin did not protrude on the surface as observed by light microscopy.

Treatment liquid (numerical values are weight% as coating solid content) Magnesium dichromate 45 wt% Vinyl acetate / Veova emulsion resin 25 wt% Ethylene glycol 8 wt% Boric acid 12 wt% Silicone resin powder 10 wt%

The preferred range of the particle size of the silicone resin is 0.5 to 3.0 times, preferably 1.0 to 2.0 times the film thickness,
If the particle size is smaller than 0.5 times, it is difficult to obtain a fine uneven coating, and the effect of improving the slipperiness after annealing is small. However, if the particle size becomes larger than 3 times the film thickness, the surface roughness becomes large and the space factor decreases, and the adhesive force of the particles becomes weak, so that the tension pad property during slit processing and after stress relief annealing It is not preferable because dusting is likely to occur in the iron core laminating process. This phenomenon was similarly observed in resin mixed coatings composed of a phosphoric acid compound other than the above or an inorganic colloid composition.

FIG. 2 is based on the following inorganic colloidal composition and organic composition in which the same finish-annealed cut plate as above is used and the addition amount of spherical silicone resin powder having a particle size of 0.5 μm is changed. A treatment liquid containing no chromic acid or phosphoric acid compound as a main component is coated with a rubber roll to a film thickness target of 0.4 μm, baked at an ultimate plate temperature of 200 ° C., and then dried with DryN ₂
This is the result of conducting the strain relief annealing at 750 ° C. in the inside and examining the slip property and the adhesion of the coating by the method described later. When the amount of silicone resin in the coating is less than 1% by weight, the coating having excellent slipperiness of the present invention cannot be obtained. However, if the addition amount exceeds 20%, the adhesion of the coating film becomes poor, and the sliding property does not show any further improvement effect.
The range is 20, preferably 5 to 20% by weight.

Treatment liquid (numerical values are values as coating solid content) Colloidal silica: 100 parts by weight Water-soluble acrylic: 100 parts by weight Silicone resin: Particle diameter 0.5 μm, content in coating 0-30% by weight

It is important that the spherical fine particles of the silicone resin are added in a monodispersed state in the coating film, and in the state where agglomerated particles are formed, spot-like adhesion defects locally occur and the surroundings thereof are present. Corrosion resistance deteriorates due to cracking of the coating. In order to disperse uniformly in the coating film, it is advisable to mix and stir with a water-soluble resin or emulsion resin in advance, and after uniformly dispersing, add to the chromate salt, phosphate salt or inorganic colloid solution of the inorganic composition. If the dispersion is still insufficient, it may be added after the aqueous dispersion treatment with ultrasonic waves using an anionic surfactant or a nonionic surfactant before mixing with the aqueous resin or emulsion resin. As the spherical silicone resin, for example, the trade name "TOSPEARL" manufactured by Toshiba Silicone Co., Ltd. can be used.

[0021]

DETAILED DESCRIPTION OF THE INVENTION

(Inorganic composition used in the present invention) Chromic acid-based compounds and phosphoric acid-based compounds as an inorganic composition which is a main component of a coating film constituent are oxides and hydroxides of Mg, Ca, Al, Zn, K and the like. , An aqueous solution in which one or more carbonates are dissolved in chromic acid or phosphoric acid, and the chromic acid compound and the phosphoric acid compound can be used alone or as a mixture of both. In the case of a treatment liquid mainly containing a chromic acid compound, polyhydric alcohols such as glycerin, ethylene glycol and sucrose may be added as a reducing agent for chromic acid in order to insolubilize the coating film. On the other hand, in the case of using a treatment solution mainly containing a phosphate compound, a trace amount of nitrate or a nonionic surfactant (described in Japanese Patent Publication No. 6-99813) is used in order to lower the temperature of the phosphate coating film formation reaction. You may add.

The inorganic colloidal composition is Si, Al, T
It is a commercially available colloidal solution of i, Zr oxide. The colloidal solution may be an acidic type or an alkaline type depending on the kind of the stabilizer of the colloid composition, but any type can be used as long as there is no problem in compatibility with the water-soluble resin or the emulsion resin. The particle size of the oxide is not particularly specified, and is 5 to 100 of a commercially available product.
Those having a size of μm can be advantageously used. If the particle size is larger than this, the content of alkali metal, sulfate, etc. increases due to the increased amount of the stabilizer, and the corrosion resistance of the coating film deteriorates, which is not preferable.

(Organic Composition Used in the Present Invention) As the second composition constituent component of the organic composition, one or more of an aqueous resin, a dispersion resin and an emulsion resin is used as a mixture with the inorganic composition. The type of resin is not particularly limited and is widely used in the prior art. For example, thermoplastic resin such as vinyl acetate resin, Veova (abbreviation of Versatech acid vinyl ester) resin, acrylic resin, polystyrene resin, polyester resin, polyethylene resin, and thermosetting resin such as phenol resin, epoxy resin, amino resin, etc. are used. it can. The content is not particularly limited, but with respect to the inorganic composition in the coating, if the content is small, the punchability is poor, and if it is excessive, the corrosion resistance and adhesion after annealing are poor, so the content is suitable. In the case of 100 parts by weight (solid content) of the inorganic composition, the organic composition is in the range of 10 to 150 parts by weight.

(Amount of Coating) The thickness of the insulating coating formed on the surface of the steel sheet after drying is limited to the range of 0.1 to 3 μm. If the film thickness is less than 0.1 μm, sufficient punching properties cannot be obtained, and as described above, the effect of improving the coating film of the present invention is to control the particle diameter and film thickness of the silicone resin to obtain a fine projection-like surface shape. Since the film of No. 1 is formed and the seizure resistance and the slip property after annealing are improved, if the film thickness becomes too thin, an appropriate surface shape cannot be created and its effect decreases. Further, if the film thickness exceeds 3.0 μm, the adhesion of the film deteriorates, which is not preferable. The film thickness is a cross-sectional film thickness obtained by observing with a light microscope, and is an average film thickness of a flat portion where the silicone resin does not project on the surface.

(Treatment Method) The treatment liquid is applied and baked by applying a predetermined amount of the treatment liquid using a roll coater or the like. The silicone resin in the treatment liquid has a true specific gravity of about 1.3, which is not so different from the specific gravity of the treatment liquid, so that no special stirring is required. It suffices to perform baking in a temperature range of 150 to 400 ° C. for a short time by using an electric furnace, a hot air oven, or the like. In the case of a treatment liquid having an inorganic colloid composition that can be baked at a low temperature, if the baking temperature is less than 150 ° C, the baking may be insufficient, and water remaining in the coating film may cause rust. On the other hand, in the case of the chromic acid-based composition and the phosphoric acid-based composition, stickiness is likely to occur. Therefore, when baking this composition at a low temperature, it is preferable to increase the amount of the reaction accelerator. When the plate temperature is 400 ° C. or higher, thermal decomposition of the organic composition proceeds, and punchability may deteriorate. Although the reasons for limiting the constituent requirements and effects in the present invention have been described above, boric acid may be added to the treatment liquid of the present invention as an adhesion improver for the film after annealing.

[0026]

EXAMPLES The present invention will be described below based on examples. (Example 1) A non-oriented electrical steel sheet having a plate thickness of 0.5 mm treated by a known method was subjected to finish annealing, and a spherical silicone resin having different particle diameters shown in Table 1 was used. The amount added was changed in the treatment liquid and the mixture was applied with a rubber roll.
Subsequently, the plate was baked at an ultimate plate temperature of 290 ° C. The film thickness of the coating is adjusted to 0 when dried by adjusting the amount of reduction of the rubber roll and the specific gravity of the treatment liquid.
The range was 2 to 4.0 μ. A sample was cut out from the steel plate after the baking and subjected to strain relief annealing at 750 ° C. × ₂ Hr in DryN ₂ to examine the film characteristics. The results are shown in Table 1. The details of each performance evaluation method are as follows. Slip is rated as ◯ or above, and otherwise is rated as Δ or above.

Treatment Liquid Composition Magnesium Dichromate 50 g Acrylic-Styrene-Epoxy Resin 20 g Ethylene Glycol 17 g Boric Acid 13 g As is apparent from Table 1, the examples of the present invention are both interlayer resistance after strain relief annealing as compared with the comparative examples. , Adhesion, seizure resistance,
It is a magnetic steel sheet having an insulating coating excellent in slipperiness and corrosion resistance.

Interlayer resistance The interlaminar resistance was measured according to JIS method 2. ◎: Over 20 Ω-cm / sheet ○: 5-20 Ω-cm / sheet Δ: 2-5 Ω-cm / sheet ×: 2 Ω-cm / sheet

Adhesion was evaluated by a film peeling rate after a 180 ° bending-back test at 20 mmφ. ⊚: No peeling ○: Less than 20% peeling Δ: 20% peeling less than 40% peeling ×: 40% peeling-all peeling

Seizure resistance 10 sheets of 50 mm square steel sheets are stacked and loaded (200 kgf /
cm ² ), after annealing at 750 ° C. for 2 hours in a nitrogen atmosphere, 500 g of the weight was dropped on the steel plate and the drop height when dividing into 5 parts was investigated. ◎: Less than 10 cm ○: 10 to less than 15 cm △: 15 to 30 cm ×: more than 30 cm

Sliding property 3 cm × 3 c in which shear burrs have been removed from the surface of the steel sheet after annealing.
A vertical load of 200 g is applied to the same steel plate of m and 160 cm /
The coefficient of kinetic friction when moving at a speed of min was evaluated. ⊚: Dynamic friction coefficient is less than 0.4 ○: 0.4 to less than 0.5 Δ: 0.5 to less than 0.6 ×: more than 0.6

Corrosion Resistance After the annealed steel plate was cut into 50 × 100 mm, it was evaluated by the red rust area ratio after 14 days of constant temperature and humidity test (50 ° C., relative humidity 80%). ◎: 0 to less than 20% ○: 20 to less than 40% △: 40 to less than 60% ×: 60 to 100%

Resistance to dusting A vertical load of 500 g was applied to the same 5 cm square steel plate from which shear burrs had been removed on the annealed steel plate surface, and the weight change rate before and after 10 reciprocations was evaluated. ◎: Less than 0.005% ○: 0.005 to less than 0.05% △: 0.05 to less than 0.1% ×: 0.1% or more

(Example 2) In the same manner as in Example 1, a base treatment liquid having an inorganic-organic mixed composition shown in Table 2 was coated with treatment agents having different addition amounts of true spherical silicone resin fine particles according to the present invention. It was applied with a roll and baked in a hot air oven. A sample was cut from this steel sheet and placed in DryN ₂ for 7
Strain relief annealing was performed at 50 ° C. for 2 hours, and the film characteristics were examined.
The film characteristics were investigated in the same manner as in Example 1. The results are shown in Table 3. Similar to Example 1, the coating film containing the silicone resin fine particles of the present invention is superior in seizure resistance after annealing, slipperiness, and interlayer resistance as compared with Comparative Example in which the silicone resin is not contained, and also in adhesion and corrosion resistance. I got good results.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[0038]

The present invention is constructed as described above, and has a film which also has the required performance as an insulating film for electromagnetic steel sheets, and is subjected to strain relief annealing for motors, transformers and the like. It can be widely used as a magnetic steel sheet, including its intended use.

[Brief description of drawings]

FIG. 1 is a diagram showing the slipperiness and dust resistance of a coating film after stress relief annealing with respect to the particle diameter / film thickness ratio of a silicone resin.

FIG. 2 is a diagram showing the relationship between the content of silicone resin particles and the slipperiness and adhesion of an annealed coating.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-240970 (JP, A) JP-A-6-101057 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 22/00 C22C 38/00 303 C23C 22/28 C23C 22/32

Claims (3)

(57) [Claims] 1. An inorganic compound containing at least one selected from a chromic acid compound and a phosphoric acid compound and an organic composition as a basic component.
After strain relief annealing, the organic mixed coating contains 1 to 20% by weight of a spherical monodispersed fine particle silicone resin having an average particle diameter of 0.5 to 3.0 times the film thickness after drying. Non-oriented electrical steel sheet with an insulating coating with excellent seizure resistance and slip resistance. 2. In an inorganic-organic mixed coating comprising an inorganic colloidal composition and an organic composition as basic components, a film thickness of 0.
An insulating coating having excellent seizure resistance and slip resistance after stress relief annealing, characterized by containing 1 to 20% by weight of spherical monodisperse fine particles of silicone resin having an average particle diameter of 5 to 3.0 times. Non-oriented electrical steel sheet having. 3. The film thickness of the insulating coating after drying is 0.1.
The non-oriented electrical steel sheet according to claim 1 or 2, wherein the non-oriented electrical steel sheet has a thickness within the range of 3 to 3 µm.