JP5125074B2 - Electrical steel sheet with insulating coating - Google Patents

Description

  The present invention relates to an electrical steel sheet having an insulating coating that does not contain Cr.

Insulating coatings on electrical steel sheets used for motors, transformers and the like are required to have not only interlayer resistance but also various characteristics. For example, convenience during processing, storage, stability during use, and the like. Furthermore, since electromagnetic steel sheets are used for various applications, various insulating coatings have been developed according to the applications.
For example, when a magnetic steel sheet is punched, sheared, bent, etc., the magnetic properties deteriorate due to residual strain. Therefore, in order to recover the deteriorated magnetic characteristics, strain relief tempering is often performed at about 750 to 850 ° C. In this case, the insulating coating must withstand strain relief annealing.

  Insulation coating (1) Emphasis on weldability and heat resistance, inorganic coating that can withstand strain relief annealing (in principle, does not include organic resin), (2) strain relief annealing with the aim of achieving both punchability and weldability It is roughly classified into three types: an inorganic coating containing an organic resin that can withstand heat resistance, and (3) an organic coating that cannot be subjected to strain relief annealing for special applications. Among these, as a general-purpose product, it is a film containing the inorganic substances (1) and (2) that can withstand strain relief annealing, and both contain a chromium compound in the film. In particular, the chromate-based insulating coating containing the organic resin in the type (2) is widely used because punchability can be remarkably improved as compared with the inorganic insulating coating.

For example, Patent Document 1 discloses that a dichromate aqueous solution containing at least one divalent metal has a vinyl acetate / veova (TM) ratio of 90/10 with respect to 100 parts by weight of CrO ₃ in the aqueous solution. A resin emulsion having a ratio of ˜40 / 60 is blended in a proportion of 5 to 120 parts by weight in terms of resin solids and an organic reducing agent in a proportion of 10 to 60 parts by weight to form a coating liquid. There is described an electrical steel sheet having an electrical insulating coating that is applied to the surface of a steel sheet and formed through a conventional baking process.

However, in recent years, environmental awareness has increased, and in response to this demand, products having an insulating coating that does not contain Cr have been desired in the field of electrical steel sheets.
In response to this situation, an electromagnetic steel sheet with an insulating coating that does not contain Cr has been proposed. Patent Document 2 describes a resin and a colloidal silica containing alumina-containing silica as a component as an insulating coating that does not contain Cr and has good punchability.

  Patent Document 3 discloses an aqueous solution in which 15 to 400 parts by weight or more of a water-soluble or emulsion type resin is added to 100 parts by weight of an inorganic colloidal substance composed of one or more of colloidal silica, alumina sol, and zirconia sol. An insulating coating formed by applying and baking is described.

  In Patent Document 4, a coating made of an oxide-based polymer containing at least one of Al, Si, Ti, and Zr is coated with an oxide fine particle (particle diameter of 10 to 10) of at least one of Al, Si, Ti, and Zr. Insulating coatings containing 35 to 90% by weight of 100 nm) are disclosed.

  Patent Document 5 describes an insulating coating mainly composed of a phosphate containing no chromium and containing a resin and optionally colloidal silica.

Further, Patent Document 6 discloses that 100 parts by weight of an organic resin is 5 to 100 parts by weight of phosphoric acid, 20 to 200 parts by weight of a compound such as Mn, Mg, and Al, ZrO ₂ , Al ₂ O ₃ , SiO ₂ , SnO. ₂ , 1 or 2 kinds of Sb ₂ O ₅ colloids (sols) are disclosed.
Japanese Patent Publication No. 60-36476 JP-A-10-130858 JP-A-10-46350 Japanese Patent No. 2861702 Japanese Patent No. 2944849 JP 9-316655 A

However, these electrical steel sheets with an insulating coating that do not contain Cr did not have sufficient scratch resistance as compared with the case of containing a chromium compound. In particular, at a weight per unit area of about 1.0 g / m ² or more, it was remarkably inferior to the conventional chromium-containing coat.

  The present invention has been made in view of the above circumstances, and is an insulating coating mainly composed of an inorganic material not containing Cr, and particularly after being baked at 300 ° C. or less and with respect to scratch resistance after strain relief annealing. An object is to provide an electrical steel sheet having an excellent insulating coating.

  The inventors of the present invention have intensively studied to solve the above problems. As a result, the inventors have found that when a specific amount of a resin having a specific ratio of carboxylic acid content is contained in the insulating coating, a coating with a good dispersion state is formed and a great improvement in scratch resistance is obtained.

The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] A steel sheet having an insulating coating containing Zr and P, wherein P is P / Zr = 0.50 to 2.50 in molar ratio to Zr, and the insulating coating has a solid content of 1 g. An electrical steel sheet having an insulating coating, characterized by containing 10 to 50% of a resin having a carboxylic acid group in an amount of 0.10 mol or more in terms of solid weight with respect to the total solid content of the coating.
[2] The electrical steel sheet having an insulating coating according to [1], wherein the resin is an acrylic resin and / or a copolymer thereof.

  According to the present invention, an electrical steel sheet having an insulating coating excellent in scratch resistance after baking and after strain relief annealing is obtained. In particular, the present invention exhibits its effect even at a baking temperature of 300 ° C. or less, and can be said to be an excellent invention from the viewpoint of reducing energy consumption and manufacturing cost.

The present invention is described in detail below.
The steel plate of the present invention is a steel plate having an insulating coating containing Zr and P, and P is P / Zr = 0.50 to 2.50 in molar ratio with respect to Zr. A resin having 0.10 mol or more of carboxylic acid groups in 1 g of a minute is contained in an amount of 10 to 50% in terms of solid weight based on the total solid content of the coating. The composition and the optimum content in such an insulating film are the most important requirements in the present invention. And by having the insulating film which consists of the above, especially after baking at 300 degrees C or less and after strain relief annealing, the electrical steel sheet excellent in scratch resistance will be obtained.

First, the electrical steel sheet used in the present invention will be described.
The electromagnetic steel plate (also referred to as an electric iron plate) before forming the insulating coating that can be used in the present invention is any steel plate (iron plate) adjusted to obtain a desired magnetic property by changing the specific resistance. A steel plate having such a composition may be used and is not particularly limited.

An example of the composition is given below. Since it is effective to increase the specific resistance for improving the iron loss, at least one selected from Si, Al, Mn, Cr, P, Ni, Cu and the like, which are specific resistance improving components, is added as necessary. It is preferable to do. The content of these elements may be determined according to the desired magnetic properties, but Si: about 5% by mass or less (including no addition, the same applies hereinafter), Al: about 3% by mass or less, Mn: about 1. 0% by mass or less, Cr: about 5% by mass or less, P: about 0.5% by mass or less, Ni: about 5% by mass or less, and Cu: about 5% by mass or less are common. The composition of a typical electrical steel sheet is one in which Si is added in an amount of 0.1% by mass or more. However, in the case of lower grades, the addition of Si: 0.05% by mass or more is preferable for improving the magnetic properties.
In addition, in order to improve the magnetic properties, at least one selected from an inhibitor forming element or a segregating element such as Mn, Se, S, Al, N, Bi, B, Sb and Sn may be added as necessary. it can. When adding an inhibitor-forming element or the like, it is usually preferable to contain these elements in a total amount of 0.5% by mass or less.
The balance other than the above is iron and inevitable impurities. Examples of the impurity include C, N, O, and a small amount of S that is less effective as an inhibitor. Less impurities are better, but if it is not a high-grade product, it may contain about 0.02 to 0.05% by mass of C.

  Moreover, the plate | board thickness of the electromagnetic steel plate of this invention is not specifically limited. A normal thickness of about 0.02 to 1.0 mm is preferable. Moreover, although it is a flat shape normally, the curved shape may be sufficient depending on the objective.

  In addition, the surface of the electrical steel sheet on which the insulating coating is formed may be subjected to any pretreatment such as degreasing treatment with alkali, pickling treatment with hydrochloric acid, sulfuric acid, phosphoric acid, etc., and finish annealing is performed. It may be an untreated surface as is.

  Furthermore, although it is not always necessary to form the third layer between the insulating coating and the surface of the ground iron, it may be formed as necessary. For example, in a normal manufacturing method, a metal oxide metal oxide film may be formed between the insulating film and the metal iron surface, but it may be possible to omit the trouble of removing this.

Next, the insulating coating of the present invention applied to the surface of the steel plate will be described.
The insulating coating of the present invention contains Zr and P as essential components, P is contained in a molar ratio of P / Zr = 0.50 to 2.50 with respect to Zr, and 0.1 g of carboxylic acid group is contained in 1 g of solid content. 10-50% of resin which has 10 mol or more is contained in conversion of solid content weight with respect to the coating-film total solid content. And the coating raw material containing these is apply | coated to the steel plate surface, and it obtains by performing a drying and / or baking process. As the coating material to be applied, an aqueous paste or liquid can be used. From the viewpoint of not increasing the coating thickness (coating adhesion amount) more than necessary and from the viewpoint of effects, it is preferable to use a liquid (aqueous liquid). In the following description, when a treatment liquid is used, in principle, liquid and pasty raw materials are also included.

Zr (Zr compound)
The insulating coating applied to the steel plate of the present invention contains a specific amount of Zr. Zr has a maximum of eight coordination numbers, and generally bonds strongly to other substances, particularly oxygen, by four bonds. For this reason, it is considered that a strong film can be formed without binding to an oxide, hydroxide, phosphate, etc. on the Fe surface and using a chromium compound.

  However, when only Zr is used as the main component of the insulating coating, the corrosion resistance is slightly inferior, and the scratch resistance after strain relief annealing tends to deteriorate greatly. This is thought to be because the network is not formed well because there are many Zr bonds, and the film becomes fragile. Therefore, the present inventors have advanced research in order to form a stronger film. As a result, it has been found that the above problem can be improved by forming a film with a combination of a specific amount of phosphate (P) and Zr.

In the present invention, examples of the Zr compound that can be used as a raw material for the insulating coating include Zr ammonium carbonate, potassium Zr carbonate, Zr sodium carbonate, Zr lithium carbonate, Zr ammonium potassium, Zr ammonium sodium carbonate, and Zr ammonium lithium carbonate. These may preferably be used alone or in combination of two or more. As Zr ammonium carbonate, (NH ₄ ) ₂ [Zr (CO ₃ ) ₂ (OH) ₂ ], (NH ₄ ) ₂ ZrO (CO ₃ ) ₂ , Zr potassium carbonate is K ₂ [Zr (CO ₃ ) ₂ (OH) ₂ ] and K ₂ ZrO (CO ₃ ) ₂ , and any of them can be suitably used.
The Zr compounds listed above contain a total of about 5% by mass or less of impurities such as Hf, Ti, or their oxides (HfO ₂ , TiO ₂ ), which are the same elements of Zr, and SiO ₂ , Fe ₂ O _3, etc. You may go out. The main impurity is Hf or HfO ₂ .

  The Zr compound may contain an alkali metal, and the content thereof is not particularly specified, but the molar ratio of the alkali metal M (K, Na, etc.) to Zr is (total amount of M) / Zr of 2.5. The following is preferable. More preferably, it is 0.2 or less. In such a range, it is considered that a good network can be formed by controlling the bonding hands of the Zr compound, and the film becomes strong. When the amount of alkali metal M is large and the molar ratio (total amount of M) / Zr exceeds 2.5, there are too few bonds and it is difficult to form a film having sufficient strength. The molar ratio (total amount of M) / Zr can be calculated from the added weight at the time of preparation. Alternatively, the abundance ratio may be taken with fluorescent X-rays.

  In the present invention, the Zr compound as a raw material for the insulating coating is preferably a water-soluble Zr compound rather than a paste-insoluble water. This is because the bond with other substances becomes strong and a denser film is formed. Here, the water-soluble one means one that dissolves in water or forms a colloid or emulsion and is stably dispersed in water.

In this specification, “converted to ZrO ₂ ” means that the content of ZrO ₂ is calculated on the assumption that all of the contained Zr forms ZrO ₂ . The same applies to the conversion of other compounds.

P (P compound)
The insulating coating applied to the steel sheet of the present invention contains a specific amount of P. P is necessary to form a film by firmly bonding with Zr. In the present invention, phosphoric acid, potassium phosphate, sodium phosphate, and the like can be used as the P compound that can be used as a raw material for the insulating coating.
P is a molar ratio of P / Zr = 0.50 to 2.50 with respect to Zr. As this ratio increases, the coating becomes stronger. However, if P / Zr is less than 0.50 or exceeds 2.50, the corrosion resistance is deteriorated. In addition, Preferably it is 0.6-1.5.
The molar ratio P / Zr can be calculated from the weight added during preparation. Further, the abundance ratio may be taken with fluorescent X-rays or the like.

In this specification, “converted to P ₂ O ₅ ” means that the content of P ₂ O ₅ is calculated on the assumption that all the contained P forms P ₂ O _5. means. Hereinafter, it is simply referred to as “P ₂ O ₅ conversion”. The same applies to the conversion of other compounds.

Resin The insulating coating of the present invention contains 10 to 50% of a resin having a carboxylic acid group of 0.10 mol or more in 1 g of solid content in terms of solid weight with respect to the total solid content of the coating. The inorganic matrix formed of P and Zr can form a uniform film with few defects (cracks) if the film is 0.1 μm or less, but if it exceeds 0.1 μm, defects will occur due to film-forming shrinkage and scratch resistance. Deteriorates. Therefore, it is conceivable to reduce the occurrence of this defect by adding a resin. However, the addition of the resin, on the contrary, often causes defects starting from the resin. Therefore, the inventors have intensively studied on the effective addition of the resin without causing defects starting from the resin. As a result, it has been found that by adding a specific amount of a resin having a specific ratio of carboxylic acid amount to the insulating film, an insulating film made of P and Zr with very few defects can be formed even with a thick film. On the other hand, if there is no carboxylic acid group or the weight of the carboxylic acid group relative to the total solid content of the coating does not satisfy a specific ratio, the resin component aggregates as shown in FIG. There may be a portion where the resin continuously exists over the interface with the base iron, which may be the starting point of the crack.
Carboxylic acid groups not only provide water solubility to the resin, but can also react with Zr to form an organic-inorganic network. Therefore, by adding a specific amount of a water-soluble resin having a specific ratio of carboxylic acid groups to the insulating coating, the dispersion state is improved and a fine particle sea-island structure can be obtained. That is, as shown in FIG. 3 (a), in the present invention, by adding a specific amount of a resin having a specific ratio of carboxylic acid groups in the insulating coating, the resin component is scattered in islands in the inorganic component. It will be in the state. And an inorganic component becomes a pumice-like shape and becomes the same thing as having essentially made the thin film. As a result, even if the coating thickness is thick, defects are extremely difficult to enter.
The ratio of the carboxylic acid group in the resin is 0.10 mol or more per 1 g of resin solid content. If the amount is less than 0.10 mol, the amount of carboxylic acid is so small that the effects of the present invention cannot be obtained. Preferably it is 0.2-0.7 mol. More preferably, it is 0.3-0.65. By using a resin having such an optimal amount of carboxylic acid groups, polyacrylic acid is approximately 0.62 and polymethacrylic acid is approximately 0.52, and these random and block copolymers allow for an arbitrary amount of carboxylic acid. Can be taken.
Moreover, the addition amount of resin needs to be 10 to 50% in solid content weight conversion (resin solid content / film total solid content) with respect to the film total solid content. If it is less than 10%, the shrinkage stress cannot be relaxed and the generation of defects cannot be suppressed. If it exceeds 50%, the pumice structure of the inorganic matrix becomes sparse and fragile.
Here, the “total solid content (weight)” of the coating is an adhesion amount after drying of the coating formed on the surface of the electrical steel sheet by a method described later. The total solid weight of the coating can be measured from the weight reduction after the coating is removed by alkali peeling.
The resin is preferably an acrylic resin and a copolymer thereof, and examples thereof include an acrylic resin, an acrylic-ethylene copolymer, a polyethylene oxide-acrylic copolymer, and a polyvinyl alcohol-acrylic copolymer. As the acrylic resin, polymethacrylic acid, polyacrylic acid, and a copolymer thereof can be used. The carboxylic acid groups of these resins may be either unneutralized or neutralized. In the case of neutralization, sodium, potassium, ammonia, amine, etc. can be used as counter ions. The molecular weight is not particularly defined, but Mw of about 500 to 1,000,000 is particularly preferable.
In addition, a resin in which a side chain in a resin having no carboxylic acid group in the skeleton is substituted with a carboxylic acid group (carboxylic acid-modified resin) can also be used as the resin of the present invention.
In addition, this invention can add another resin (resin which does not contain a carboxylic acid group) in the range which does not prevent the effect of this invention. Other resins include polyolefin resins such as polyethylene and polypropylene, polyester resins, alkyd resins, styrene resins, vinyl acetate resins, epoxy resins, phenol resins, polyester resins, urethane resins, melamine resins, etc. Resins (emulsion, dispersion, water-soluble) can be mentioned. These may be an oxidation treatment, a block copolymer, or a graft copolymer in order to improve emulsification and compatibility with other materials. The addition amount is preferably 30% or less in terms of solid weight with respect to the total solid content.

  From the above, the present invention can achieve the desired characteristics with the electromagnetic steel sheet having the insulating coating made of Zr, P, and the resin, but does not impair the effects of the present invention in addition to the above contents. Within the range, the following additives, other inorganic compounds, and organic compounds can be contained in the insulating coating for the purpose shown below.

Additives In order to further improve the performance and uniformity of the coating, the insulating coating of the present invention is optionally provided with a surfactant (nonionic, cationic, anionic surfactant; silicone surfactant; acetylenic diol). ), Rust preventives (amine-based, non-amine-based rust preventives, etc.), boric acid, silane coupling agents (aminosilane, epoxysilane, etc.), and organic and inorganic additives such as lubricants (wax, etc.) be able to. As these additives, known ones that are applied to conventionally known chromate-based insulating coatings and non-chromate insulating coatings that have been proposed so far can be used.
When these additives are used, in order to maintain sufficient film properties, it is preferable that the content be about 10% or less with respect to the total solid weight of the insulating film of the present invention.

Other inorganic compounds and organic compounds The insulating coating of the present invention may contain other inorganic compounds and / or organic compounds to the extent that the effects of the present invention are not impaired. For example, another oxide sol can be added as long as the liquid stability can be secured. Examples of the oxide sol include alumina sol, iron sol, titania sol, tin sol, cerium sol, antimony sol, tungsten sol, and molybdenum sol.
In addition, this invention aims at obtaining a favorable film characteristic, without adding a chromium compound. Therefore, it is preferable that the insulating coating of the present invention substantially does not contain Cr from the viewpoint of preventing environmental contamination from the manufacturing process and products. The amount of chromium allowed as an impurity is preferably 0.1% or less in terms of CrO ₃ with respect to the total solid weight of the insulating coating.
The insulating coating of the present invention can contain a Si compound to the extent that the effects of the present invention are not impaired. Colloidal silica is preferably applied as the Si compound contained in the treatment liquid. Colloidal silica is an inorganic colloid mainly composed of SiO ₂ and is often amorphous. The particle diameter of colloidal silica is preferably 200 nm or less, more preferably 100 nm or less. Although the lower limit is not particularly limited, it is considered that when the content is ultrafine, even if the content is the same, the entire surface area becomes large, so that the interaction with other components increases and the strength of the coating increases. In addition, when the particle diameter is small, aggregation is likely to occur between the silica particles and other components, so the colloidal silica concentration should be adjusted to a low level. Conversely, the particle size may be set to a practically suitable particle size from a desired concentration.
In addition, an average particle diameter can be measured by BET method (converted from the specific surface area by an adsorption method). It is also possible to substitute an average value (in terms of sphere diameter) actually measured from an electron micrograph.
It is desirable that the Si compound used in the present invention does not contain other metal elements at an impurity level or more. Other possible impurities are preferably Na ₂ O: 5% or less, Cl: 5% or less, and SO4: 3% or less with respect to the SiO ₂ equivalent weight.

Next, the manufacturing method of the electrical steel sheet which has an insulating film of this invention is demonstrated.
<Method for producing insulating coating>
A method for producing the insulating coating of the present invention on the surface of the electromagnetic steel sheet will be described.
The pretreatment of the electrical steel sheet used as the starting material of the present invention is not particularly defined. After finish annealing, untreated or washed with water, degreasing treatment such as alkali, and pickling treatment such as hydrochloric acid, sulfuric acid and phosphoric acid are preferably applied. And the processing liquid containing the said Zr compound, the said P compound, the said resin, and the said additive etc. as needed further is apply | coated on this electromagnetic steel plate. Thereafter, an insulating coating is formed by subjecting the magnetic steel sheet coated with the treatment liquid to a baking treatment as necessary.
As a method for applying the insulating coating, a method using various facilities such as a roll coater, a flow coater, a spray, and a knife coater, which are generally used in industry, can be applied. In addition, a hot air method, an infrared heating method, an induction heating method, or the like, which is usually performed, is also possible for the baking method. Although the baking temperature should just be a normal level, 100 to 350 degreeC is preferable. A more preferable range is 150 ° C. or higher and 300 ° C. or lower.

Distortion annealing The electrical steel sheet with an insulating coating of the present invention can be subjected to strain relief annealing to remove, for example, distortion caused by punching. As a preferable strain relief annealing atmosphere, an atmosphere in which iron is not easily oxidized, such as an N ₂ atmosphere or a DX gas atmosphere, is applied. However, there is an advantage in slight oxidation, and in the above atmosphere, the dew point is high, for example, Dp: set to about 5 to 60 ° C., and the corrosion resistance can be further improved by slightly oxidizing the surface and the cut end face.
A preferred strain relief annealing temperature is 600 ° C. or higher and 900 ° C. or lower. A more preferred lower limit is 650 ° C., more preferably 700 ° C. or more. Furthermore, it is more preferable to set the temperature around 750 ° C. or 750 ° C. or higher. On the other hand, a more preferable upper limit is 850 ° C. The holding time in strain relief annealing is preferably longer, but more preferably 2 hours or longer.

Amount of insulating coating attached The amount of insulating coating attached is not particularly specified, but is preferably 0.01 g / m ² or more and 5 g / m ² or less in total per side. In addition, the amount of adhesion, ie, the measurement of the total solid content in the insulating coating of the present invention, can be measured from the weight reduction after removal of the coating by alkali peeling. Moreover, when there is little adhesion amount, you may measure using a fluorescent X ray. In this case, it is preferable to calculate the adhesion amount using a calibration curve created using the alkali peeling method.
If the adhesion amount is less than 0.01 g / m ² , corrosion resistance and insulation may be insufficient. Moreover, when the adhesion amount exceeds 5 g / m ² , workability in coating may be deteriorated. More preferably, it is 0.1 g / m ² or more and 3.0 g / m ² or less. Even more preferably, it is 0.2 g / m ² or more and 2.5 g / m ² or less.
The coating and insulating coating of the present invention are preferably on both sides of the steel sheet, but depending on the purpose, only one side may be used. That is, depending on the purpose, only one surface may be applied, and the other surface may be another insulating coating, or the other surface may not be provided with an insulating coating.

Second insulation coating (upper coating)
The surface of the insulating coating of the present invention (hereinafter referred to as “undercoat”) can further have a second insulating coating (hereinafter referred to as “upper layer”) having a component different from that of the undercoat.
Here, at least one layer of the upper layer film may be formed on the surface of the base film, but two or more layers may be formed. Although it is not necessary to specifically limit each upper layer coating composition, it is preferable that Cr is not included substantially for the same reason as the base coating.
The upper layer film of the present invention can be produced by the same method as that for the undercoat film. That is, an upper layer film can be manufactured on the surface of the base film manufactured by the above method by a similar method. It should be noted that when the electromagnetic steel sheet on which the upper layer film of the present invention is formed is subjected to strain relief annealing, it may be the same as the annealing method when only the base film is formed.
The amount of the coating on the upper layer coating is arbitrary, but the amount of the base coating is 0.001 to 1.0 g / m ² and the amount of the upper coating is 0.04 to 4.0 g / m 2. ² is preferable. Within this range, the base coating becomes a thin insulating coating, and cracks that are considered to cause corrosion resistance deterioration are particularly difficult to enter. Adhesion amount of the underlying coating, more preferably to 0.005 g / ^{m 2} or more, and even more preferably to a 0.01 g / ^{m 2} or more. Moreover, it is more preferable to set it as 0.2 g / m < ² > or less.
On the other hand, the addition of the upper layer film is very useful for ensuring insulation, and it is preferable to apply a thicker film, for example, 0.2 g / m ² or more in order to seal scratches and defects in the base film.
In addition, the effect which improves an external appearance is seen by setting it as the thin base treatment. When the upper layer is applied after applying the base, it is considered that the Fe elution of the steel sheet, which is likely to occur with the aqueous treatment liquid, is suppressed and the appearance is improved.

Hereinafter, although the effect of the present invention is concretely explained based on an example, the present invention is not limited to these examples.
A P compound, a Zr compound, and a resin were added to deionized water so as to have an insulating coating composition shown in Table 1, and each treatment solution for the first layer (single layer coating or base coating) was prepared. Here, the total amount of P ₂ O ₅ , ZrO ₂ conversion amount, and resin solid content weight was adjusted to be a treatment liquid added with 80 g / l with respect to the amount of deionized water.
Next, each of these treatment liquids was applied by a roll coater to the surface of a test piece cut into a size of 150 mm in width and 300 mm in length from a 0.5 mm thick electromagnetic steel sheet (Si: 0.25% by mass), After baking at an ultimate temperature of 230 ° C. by direct heating with propane gas, it was allowed to cool at room temperature to form an insulating coating. The basis weight was 1.6 g / m ² per side.
The electromagnetic steel sheet having the insulating coating obtained as described above was evaluated for scratch resistance by the following method.
<Scratch resistance after baking (product plate) and after strain relief annealing>
The surface of the sample was scratched with an edge made by shearing the same steel plate, and the degree of scratches and powder blowing was judged.
Furthermore, the surface of the sample that had been subjected to strain relief annealing while being held at 750 ° C. for 2 hours in an N ₂ atmosphere was subjected to the same method as described above, and scratch resistance was evaluated according to the same criteria.
(Criteria)
A: Scratch and powder generation are hardly observed B; Slight rubbing and slight dusting are observed C; Rubing and dusting are clearly visible D; The results obtained from the above are shown in Table 1, FIG. 1 and FIG. 2 together with the experimental conditions. In Table 1, A: A, B: B, C: A, D: X.

As is apparent from Table 1, the present invention example is excellent in scratch resistance in both the product plate and the strain relief annealed plate. On the other hand, in the comparative example, both the product plate and the strain relief annealed plate are inferior in scratch resistance.
FIG. 1 is a graph showing the effect of the amount of carboxylic acid (horizontal axis) of the resin added to the insulating coating on scratch resistance (vertical axis). From FIG. 1, the proportion of carboxylic acid groups in the resin is When the amount is 0.20 mol / g or more, the scratch resistance is も し く は or ○, and it can be seen that it is good.
Fig. 2 is a graph showing the effect of the amount of resin added to the insulating coating (both carboxylic acid content is 0.10 mol / g or more) (horizontal axis) on scratch resistance (vertical axis). Further, it can be seen that when the amount of the resin added is 10 to 50%, the scratch resistance is ◎ or も し く は, which is good.

  Although it is an insulating film mainly composed of an inorganic material that does not contain Cr, it has performance equivalent to or better than that of a Cr-containing insulating film, such as scratch resistance, and is expected to be used in a variety of applications, particularly in motors and transformers. Is done.

It is a figure which shows the influence which the carboxylic acid amount (horizontal axis) of the resin added to an insulating film has on scratch resistance (vertical axis). Example 1 It is a figure which shows the influence which the addition amount (horizontal axis) of resin (the amount of carboxylic acid is 0.10 mol / g or more) added to the insulating coating has on the scratch resistance (vertical axis). Example 1 It is a figure which shows the dispersion state of resin in the insulating film of the example of this invention and a comparative example.

Claims (2)

A steel sheet having an insulating coating containing Zr and P,
P is a molar ratio of P / Zr = 0.50-2.50 with respect to Zr,
An insulating coating comprising 10 to 50% of a resin having a carboxylic acid group of 0.10 mol or more in 1 g of solid content in terms of solid content weight based on the total solid content in the insulating coating. Having electrical steel sheet.   The electrical steel sheet having an insulating coating according to claim 1, wherein the resin is an acrylic resin and / or a copolymer thereof.

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