JP2005015838A - Magnetic steel sheet with insulation film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic steel sheet with chromium-free insulation film excellent in powdering resistance and scratch resistance after annealing for removing the strain. <P>SOLUTION: The magnetic steel sheet with insulation film excellent in the powdering resistance contains ≥40 mass% the total content of an Al compound and Si compound in terms of Al<SB>2</SB>O<SB>3</SB>and SiO<SB>2</SB>respectively and 40-95 mass% of the ratio of the Al compound in the Al compound and the Si compound and in terms of Al<SB>2</SB>O<SB>3</SB>/(Al<SB>2</SB>O<SB>3</SB>+SiO<SB>2</SB>) further, contains resin at <50% in terms of the resin solid content/(Al<SB>2</SB>O<SB>3</SB>+SiO<SB>2</SB>+resin solid content). In the insulation film, the resin can be contained. The sheet applying the annealing for removing the strain has excellent scratch resistance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３４】
【表２】

【００３５】
実施例および比較例における評価結果（製品板の耐粉吹き性および焼鈍板の耐キズ性）を、絶縁被膜のＡｌ_２ Ｏ_３ ／（Ａｌ_２ Ｏ_３ ＋ＳｉＯ_２ ）比率との関係で図１に、樹脂固形分／（Ａｌ_２ Ｏ_３ ＋ＳｉＯ_２ ＋樹脂固形分）比率との関係で図２にそれぞれ示す。
表１、図１および図２から明らかなように、本発明の構成規定を満たす実施例は、いずれも製品板の耐粉吹き性、歪取り焼鈍前後の耐キズ性に優れている。
【００３６】
【発明の効果】
本発明により、耐粉吹き性に優れ、歪取り焼鈍後の耐キズ性にも優れるクロムフリーの絶縁被膜付き電磁鋼板が提供される。
【図面の簡単な説明】
【図１】本発明の実施例における製品板および焼鈍板の評価結果を示す図である。
【図２】本発明の実施例における製品板および焼鈍板の評価結果を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chromium-free electrical steel sheet with an insulating coating that has excellent powder blowing resistance and excellent scratch resistance after strain relief annealing.
[0002]
[Prior art]
Since electrical steel sheets are used for various applications, various insulating coatings have been developed according to the applications. For example, insulating coatings on electrical steel sheets used for motors, transformers, and the like are required not only for interlayer resistance but also for various characteristics such as convenience during processing and storage, and stability during use.
In addition, when magnetic steel sheets are subjected to punching, shearing, bending, etc., the magnetic properties deteriorate due to residual strain. In order to recover the deteriorated magnetic characteristics, the processed magnetic steel sheet is often subjected to strain relief annealing at about 750 to 850 ° C. In this case, the insulating coating must withstand strain relief annealing.
[0003]
Conventionally known insulating coatings are roughly classified into three types: (1) inorganic coatings, (2) resin-containing inorganic coatings, and (3) organic coatings. Among these, (3) is a special purpose insulating coating that cannot be subjected to strain relief annealing, but the insulating coatings (1) and (2) containing an inorganic substance are general-purpose products that can resist strain relief annealing. Among these, the resin-containing inorganic coating (2) can achieve both weldability and punchability compared to the inorganic coating (1) which places importance on weldability and heat resistance, and particularly compared with the inorganic coating (1). The punchability is remarkably excellent. In addition, the insulating film of (2) can be obtained by applying a treatment liquid containing an inorganic organic resin and an inorganic material to the surface of the magnetic steel sheet and then baking it by a conventional method, that is, by one coat and one bake. Because it is widely used. As a specific example of (2), for example, the use of a treatment liquid containing an organic reducing agent together with a vinyl acetate / veova resin emulsion in a dichromate-based aqueous solution containing a divalent metal causes generation of bad odor during welding. There is a disclosure of an insulating coating that is suppressed (see, for example, Patent Document 1).
[0004]
However, all conventional general-purpose strain relief annealing coatings include a Cr compound as an inorganic material. In recent years, due to an increase in environmental awareness, an insulating coating that does not contain Cr is desired even at the manufacturing site of an electromagnetic steel sheet or in an environment where it is used. For this reason, it is substantially free of Cr, but an insulating coating with good punchability (commonly referred to as a chromium-free insulating coating) is being sought in the same manner as conventional Cr-containing insulating coatings. Several chromium-free insulating coatings of the above type (2) containing Mo, W, Ti, Zr, Sb, etc. in the form of oxides such as silica and alumina have been proposed. Among these, as a specific example of forming an insulating film using a water-based paint containing colloidal silica and resin, a combination of colloidal silica (alumina-containing silica) and a resin having a Tg of 30 to 150 ° C. is used. There is a disclosure that an insulating film having good solvent properties can be produced by low-temperature baking (for example, see Patent Document 2).
[0005]
[Patent Document 1]
Japanese Patent Publication No. 60-36476 [Patent Document 2]
Japanese Patent Laid-Open No. 10-130858
[Problems to be solved by the invention]
Insulating coating made by applying and baking water-based paint containing colloidal silica and resin to magnetic steel sheet generates a large amount of dust on the tension pad in slit machining of magnetic steel sheet (product plate) before strain relief annealing, or strain relief annealing. When handling the plate, scratches may occur and the coating may peel off.
The present invention solves the above-mentioned problems, and in addition to being excellent in coating properties such as punching workability, in particular, it is improved in the powder blowing resistance of product plates and the scratch resistance of strain relief annealed plates. An object of the present invention is to provide an electromagnetic steel sheet with an insulating coating.
[0007]
[Means for Solving the Problems]
As a result of diligent investigations to solve the above problems, the inventors of the present invention include a specific amount of Al together with Si in a specific amount that is much larger than the amount of Al contained in ordinary colloidal silica, as will be described later. It has been found that an electrical steel sheet with an insulating coating having the coating properties as described above can be obtained. Furthermore, such an insulating film has good film characteristics, and therefore, by adding a small amount of resin, it has film characteristics such as punching workability equivalent to conventional resin-containing insulating films even if no resin is included. The present invention was completed by obtaining the knowledge that the strain relief annealed plate has good scratch resistance.
[0008]
The present invention is an electrical steel sheet having an insulating coating on the surface, wherein the insulating coating contains 40 mass% or more of the total amount of Al compound and Si compound in terms of Al ₂ O ₃ and SiO _{2 in} the total amount of the coating, and with the ratio of these Al compounds and Si Al compound in the compound is 40～95Mass% in _{Al 2 O 3 / (Al 2} O 3 + SiO 2) in terms of the resin solid content of the resin _{/ (Al} 2 O 3 + SiO _{The present} invention provides an electrical steel sheet with an insulating coating that is excellent in powder blowing resistance and scratch resistance and contained in an amount of less than 50% in terms of ( ₂ + resin solid content).
[0009]
In the electrical steel sheet with an insulating coating (a product plate before strain relief annealing), the Al compound is preferably an Al organic acid compound containing a hydroxyl group and / or a dehydration reaction product thereof.
Specifically, as the organic acid compound of Al containing a hydroxyl group, one selected from the group consisting of basic aluminum acetate, basic aluminum formate, basic aluminum lactate, basic aluminum citrate and basic aluminum tartrate or A combination of two or more is preferred.
[0010]
The Si compound is preferably colloidal silica having an average particle size of 10 nm or less.
[0011]
The present invention also provides the above-mentioned electrical steel sheet with an insulating coating (annealing plate) that has been subjected to strain relief annealing and has an insulating coating composed of Al, Si, and O elements and excellent in scratch resistance. The strain relief annealing is usually performed at 500 ° C. or higher.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the electrical steel sheet with an insulating coating according to the present invention will be specifically described based on an example of a manufacturing process thereof.
In the present invention, the electromagnetic steel plate (electric iron plate) may be a steel plate having any composition adjusted to obtain a desired magnetic characteristic by changing the specific resistance, and is not particularly limited. Moreover, the surface of the electrical steel sheet on which the insulating coating is formed may be left untreated or may be pretreated. Pretreatment is optional, but degreasing treatment with alkali or the like, and pickling treatment with hydrochloric acid, sulfuric acid, phosphoric acid or the like are preferably applied.
[0013]
An electromagnetic coating substantially free of chromium is formed on the surface of the electromagnetic steel sheet using a treatment liquid containing an Al compound and a Si compound as inorganic substances.
In order to apply and bake the treatment liquid on the steel sheet in the form of a water-based paint, the Al compound is preferably water-soluble or dispersible in a colloidal or suspended state. In the present invention, it is particularly preferable to use an Al organic acid compound containing a hydroxyl group and / or a dehydration reaction product thereof as the Al compound. Specifically, the organic acid compound of Al containing a hydroxyl group is one or two selected from the group consisting of basic aluminum acetate, basic aluminum formate, basic aluminum lactate, basic aluminum citrate and basic aluminum tartrate. The combination of the above is mentioned. If an equivalent effect is obtained, it is possible to replace the organic acid with another.
[0014]
Among these, basic aluminum acetate represented by the molecular formula Al _x (OH) _y (CH ₃ COO) _z (where x, y, and z are each 1 or more) is preferable, and particularly Al ₂ (OH) ₅ (CH ₃ COO) is preferred. This is because it can exist in a colloidal state of several nanometers from a dissolved state at the molecular level, and a fine homogeneous dispersion coating material can be formed. In the thermal analysis, since a large dehydration reaction peak is observed at about 200 to 230 ° C., a film can be formed by forming an intermolecular network by dehydration condensation. By further heating, dehydration and deacetic acid reactions occur up to about 500 ° C., and the network becomes stronger. If the temperature exceeds 500 ° C. to 625 ° C. and reaches the strain relief annealing temperature, amorphous alumina, γ-alumina or δ- It is thought that it becomes alumina and a strong film is formed.
[0015]
As the Si compound, colloidal silica is preferably applied.
Colloidal silica is an inorganic colloid mainly composed of SiO ₂ and is often amorphous. The particle diameter is preferably 20 nm or less, more preferably 10 nm or less. The smaller the particle diameter, the better the film can be formed, so the lower limit is not particularly limited. This is presumably because the finer the colloidal silica particles, the larger the surface area, and the higher the interaction with the Al compound or resin, the stronger the coating. However, the concentration of colloidal silica has to be reduced because the silica particles tend to aggregate with each other and with the Al compound as the particle size decreases. Considering these points, the particle diameter can be set to be practical.
The average particle size can be measured by the BET method (converted from the specific surface area by the adsorption method). It is also possible to substitute an average value actually measured from an electron micrograph. In addition, the said particle diameter is a particle diameter of colloidal silica itself, Comprising: The thickness of surface treating agents (Al compound etc.) is not included.
[0016]
In the present invention, the Al coating and the Si compound as described above are included in the insulating coating in amounts such that the Al ₂ O ₃ / (Al ₂ O ₃ + SiO ₂ ) conversion ratio is 40 to 95 mass%. If the ratio of the Al compound calculated above is less than 40 mass%, the basic aluminum acetate as a film-forming component is insufficient, and a sufficiently strong film is not formed. On the other hand, if it exceeds 95 mass%, the coating solution is not stable due to highly reactive basic aluminum acetate, and it becomes difficult to obtain a uniform film. The ratio of the Al compound in the total amount of the Al compound and the Si compound only needs to be within the range of the oxide conversion ratio, and the optimum ratio varies depending on the colloidal silica particle size, etc. , Preferably it is 50-85 mass%. The preferred composition is a composition close to mullite _{(3Al 2} O 3 · 2SiO ₂ Composition) Ratio 72Mass% calculated on the.
[0017]
When the Al compound and the Si compound are included in the insulating film in the above quantitative ratio, a mixture of the basic aluminum acetate represented by the above molecular formula and colloidal silica is suitable as a combination of the Al compound and the Si compound. Applicable to. When basic aluminum acetate is used for the surface modification of colloidal silica, the (−) charge on the surface of the colloidal silica is reacted with the (+) charge, and the minimum addition amount covering the surface is prescribed. Since the surface area of the basic aluminum acetate at this time varies depending on the colloidal silica particle diameter, the ratio varies depending on the colloidal silica particle diameter. For example, when the particle size of colloidal silica is 13 nm, the ratio of the Al compound is about 9%, about 13% for 9 nm, and about 21% for 5 nm.
[0018]
In the present invention, the Al compound is contained in a much larger amount than the usual silica surface treatment amount, and it should be a mixture of colloidal silica and basic aluminum acetate rather than surface treatment. That is, it is considered that basic aluminum acetate takes a form in which there are many free ones other than those adsorbed on the surface of colloidal silica. Such Al compound and Si compound are considered to be a mixture of amorphous alumina and / or γ-alumina and / or δ-alumina and silica after treatment at the strain relief annealing temperature. The combination of aluminum hydroxide and cinnabar is about 1400 ° C., and the combination of alumina sol and colloidal silica is about 1200 ° C., respectively. When used, it is presumed that it can partially become mullite or an aluminosilicate having a composition close to mullite even at a low temperature.
[0019]
Although the stabilizer for the Al compound is not particularly specified, for example, organic acids such as formic acid, acetic acid, lactic acid, propionic acid are suitably applied as the stabilizer for basic aluminum acetate. Other stabilizers may be used as long as the coating properties of the present invention are not impaired.
[0020]
In the present invention, in the insulating film, and Al compounds as described above and Si compound, _Al 2 _{O 3} and SiO ₂ in a total amount of conversion 40 mass% or more, preferably containing at least 50 mass%. When the total amount of the Al compound and the Si compound is less than 40 mass%, a sufficient network cannot be formed, and a powder blowing state is not preferable.
[0021]
In the present invention, it is desirable that the treatment liquid containing the Al compound and the Si compound for forming an insulating coating contains a resin in a specific amount or less, which will be described later. The resin may not be contained, but the inclusion of an appropriate amount tends to improve the film properties before the strain relief annealing. This is considered to be for assisting the film formation of the Al compound, preferably basic aluminum acetate, by being combined with the resin. In addition, when the temperature is higher than the decomposition temperature of the resin, for example, 300 ° C. or higher, the decomposition of the resin and the dehydration / deacetication of basic aluminum acetate proceed almost simultaneously, so that not only the primary film formation but also the secondary film formation proceeds smoothly. It is thought that there is.
[0022]
In order to obtain such an effect, it is desirable that the resin is contained in an amount of 5 mass% or more in terms of resin solid content / (Al ₂ O ₃ + SiO ₂ + resin solid content). On the other hand, if it is 50 mass% or more, the formation of the basic aluminum acetate network is inhibited, and therefore the coating tends to be brittle before and after strain relief annealing, so it is set to less than 50 mass%. More preferably, the resin amount specified above is 5 to 40 mass%.
[0023]
The resin is not particularly specified, but one or more aqueous resins (emulsions, acryl resins, alkyd resins, polyolefin resins, styrene resins, vinyl acetate resins, epoxy resins, phenol resins, urethane resins, melamine resins, etc.) It is preferable to use dispersion and water solubility. Further, it is preferable to use a resin having a glass transition point (Tg) of 30 to 150 ° C.
[0024]
In order to further improve the performance and uniformity of the coating, additives such as a surfactant and a rust preventive may be added to the treatment liquid as necessary. In this case, in order to maintain sufficient film properties, the total amount added is preferably about 10% or less with respect to the film after drying.
[0025]
A coating film is formed on the magnetic steel sheet by applying and baking the above treatment liquid containing an Al compound, Si compound, resin, and the like. As a coating method, various methods such as a roll coater, a flow coater, a spray, and a knife coater that are generally used in industry can be applied. As for the baking method, a hot air method, an infrared method, an induction heating method and the like which are usually performed can be applied.
[0026]
The adhesion amount (weight after drying) of the insulating coating on the surface of the electrical steel sheet is not particularly specified, but it is preferably 0.05 to 5 g / m ² on the surface on one side. Adhering amount is insufficient in corrosion resistance is less than 0.05 g / m ^2, whereas, when the adhesion amount is 5 g / m ^2, greater than the adhesion is lowered, paintability such blistering occurs during high temperature drying decreases Tend to. More preferably, it is 0.1-3.0 g / m < ² >. The insulating coating is usually formed on both sides, but in some cases, it may be formed only on one side.
[0027]
The magnetic steel sheet (product plate) having the insulating coating as described above is not only excellent in the coating properties during punching, but also does not generate a large amount of dust in the tension pad during slitting, and is resistant to dust blowing. Are better.
Further, the product plate of the present invention can be applied with strain relief annealing, and even when subjected to strain relief annealing, it is difficult for scratches to occur during handling of the annealed plate.
[0028]
Scratch resistance after strain relief annealing is affected by the stress relief annealing conditions, especially temperature, and the higher the temperature, the better the decomposition of the resin and the easier the film formation by basic aluminum acetate dehydration / deacetic acid reaction. An insulating coating can be formed. For this reason, it is necessary to perform strain relief annealing at a temperature of 500 ° C. or higher to decompose the resin to form a basic aluminum acetate film. By performing strain relief annealing at 500 ° C. or higher, the insulating film containing the Al compound, Si compound and, optionally, a resin, and further other additives mainly contains Al, Si and O elements, and residual C. It becomes an insulating film composed of impurities.
As a preferred strain relief annealing atmosphere, an atmosphere that is not easily oxidized, such as an N ₂ atmosphere or a DX gas atmosphere, is preferably applied. At this time, the dew point can be set high (about Dp60 ° C.). Moreover, as preferable strain relief annealing temperature, it is 700-900 degreeC, More preferably, it is 750-850 degreeC. A longer holding period of the strain relief annealing temperature is preferred, but the usual 2 hours or more is particularly preferred.
[0029]
The electrical steel sheet with an insulating coating according to the present invention that has been subjected to strain relief annealing exhibits excellent scratch resistance.
[0030]
【Example】
EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these Examples.
(Examples 1-36 and Comparative Examples 1-9)
Each treatment liquid containing the Al compound, Si compound (colloidal silica) and resin described in Table 1 in the quantitative ratio shown in Table 1 was prepared.
A basic aluminum acetate having a molecular formula of Al ₂ (OH) ₅ (CH ₃ COO) was used.
The above treatment liquid is applied to the surface of an electric iron plate (magnetic steel plate) having a thickness of 0.5 mm, a width of 150 mm, and a length of 300 mm with a roll coater, baked at a final plate temperature of 230 ° C. by direct propane gas fire, and then released. It cooled and formed the insulating film.
Table 1 shows the evaluation of the powder blowing resistance of each of the electrical steel sheets (product sheets) with an insulating film obtained above.
[0031]
<Powder resistance of product plate>
Test conditions: felt contact surface 10 × 10 mm, load: 7 kg, 40 m
Judgment criteria ◎: Almost no generation of powder ○: Slight rubbing and slight dusting △; Scratch and dusting clearly visible ×;甚 大 【0032】
The product plate was subjected to strain relief annealing at 750 ° C. for 2 hours. The scratch resistance (scratch) resistance of the annealed plate is shown in Table 1.
<Scratch resistance of annealed plate>
The shear end was reciprocated 10 times on the surface of the coating and scratched, and the degree of scratching of the coating was determined visually.
Judgment criteria ◎: Most scratches are not recognized ○: Scratch marks are slightly distinguishable △: Base iron is slightly exposed ×;
[Table 1]

[0034]
[Table 2]

[0035]
The evaluation results (powder blowing resistance of product plates and scratch resistance of annealed plates) in Examples and Comparative Examples are shown in FIG. 1 in relation to the Al ₂ O ₃ / (Al ₂ O ₃ + SiO ₂ ) ratio of the insulating coating. FIG. 2 shows the relationship between the resin solid content / (Al ₂ O ₃ + SiO ₂ + resin solid content) ratio.
As is apparent from Table 1, FIG. 1 and FIG. 2, all the examples satisfying the constitutional regulations of the present invention are excellent in the powder blowing resistance of the product plate and the scratch resistance before and after the strain relief annealing.
[0036]
【The invention's effect】
According to the present invention, there is provided a magnetic steel sheet with a chromium-free insulating coating that has excellent powder blowing resistance and excellent scratch resistance after strain relief annealing.
[Brief description of the drawings]
FIG. 1 is a diagram showing evaluation results of product plates and annealed plates in an example of the present invention.
FIG. 2 is a diagram showing evaluation results of product plates and annealed plates in examples of the present invention.

Claims (5)

An electrical steel sheet having an insulating coating on the surface, wherein the insulating coating contains 40 mass% or more of the total amount of Al compound and Si compound in terms of Al ₂ O ₃ and SiO _{2 in} the total amount of the coating, and these Al compounds And the ratio of the Al compound in the Si compound is 40 to 95 mass% in terms of Al ₂ O ₃ / (Al ₂ O ₃ + SiO ₂ ), and the resin is resin solid content / (Al ₂ O ₃ + SiO ₂ + resin solid Min) An electrical steel sheet with an insulating coating excellent in powder blowing resistance and scratch resistance, which is contained in an amount of less than 50% in terms of conversion. The electrical steel sheet with an insulating coating according to claim 1, wherein the Al compound is an Al organic acid compound containing a hydroxyl group and / or a dehydration reaction product thereof. The Al organic acid compound containing a hydroxyl group is one or a combination of two or more selected from the group consisting of basic aluminum acetate, basic aluminum formate, basic aluminum lactate, basic aluminum citrate and basic aluminum tartrate The electrical steel sheet with an insulating coating according to claim 2, which is a combination. The electrical steel sheet with an insulating coating according to any one of claims 1 to 3, wherein the Si compound is colloidal silica having an average particle diameter of 10 nm or less. The electrical steel sheet with an insulating coating according to any one of claims 1 to 4, which is made of Al, Si, and O and has an insulating coating with excellent scratch resistance and subjected to strain relief annealing.

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