JPH06101057A - Non-oriented silicon steel sheet excellent in film property and surface treating agent for the steel sheet - Google Patents

Abstract

PURPOSE:To provide a non-oriented silicon steel sheet excellent in lubricity, corrosion resistance, insulating properties or the like after being subjected to stress relieving annealing as well as excellent in punching properties, weldability or the like, and to provide a treating agent therefor. CONSTITUTION:A steel sheet is coated with a treating agent essentially consisting of, as organic substance, one or >= two kinds among epoxy, styrene, phenol, melamine, polyester, vinyl acetate, acrylic, silicone series emulsion resin with 0.5 to 3.0mum grain size and one or >= two kinds among the chromates of Al, Mg, Ca, Zn or the like, and a coating-baking is executed. In this way, the non-oriented silicon steel sheet in which an insulated film having 0.15 to 0.6mum surface roughness by Ra value (average roughness in the center line) is formed and the shape of spherical projection formed on the surface by coarse- grained emulsion is regulated to <=3mum diameter and <=3mum height can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to punchability, weldability,
The present invention relates to a non-oriented electrical steel sheet having excellent film characteristics such as occupation ratio before annealing, and excellent properties such as lubricity, insulation and corrosion resistance of the film after annealing, and a surface treatment agent for the steel sheet.

[0002]

2. Description of the Related Art An electromagnetic steel sheet is used after the surface of the steel sheet is treated with an insulating coating and baked to reduce iron loss due to eddy currents. The core of motors or transformers that use electromagnetic steel sheets is manufactured by slitting electromagnetic steel sheets or strips to a specified width and then punching or cutting them continuously into an iron core shape and stacking them, and then welding or caulking the edges of this laminate. It is manufactured by the process of fixing. The iron core is then subjected to strain relief annealing in a temperature range of 700 to 800 ° C., if necessary, and then wound, and inserted into a case to be a final product.

Therefore, the insulating coating formed on the surface of the magnetic steel sheet is not only excellent in insulation, but also excellent in punchability, adhesion, heat resistance, and oil resistance, and reduces the space factor of the magnetic steel sheet. It is required to have characteristics such as not existing. As a special case, in the case of a transformer iron core, for example, when there is a re-lamination step after annealing like an EI core, the workability during lamination is affected by the slipperiness of the steel sheet surface, so It is also important to have excellent slipperiness and scratch resistance.

Various methods for forming an insulating coating have been proposed in order to satisfy these characteristics required for the insulating coating. Generally, 1) an all inorganic component type coating agent containing phosphate or chromate as a main component is used, and 2) a semi-organic component type coating agent based on chromate and containing an organic resin is added. There are three types, that is, the one used, and the one using a coating agent of the total organic component type consisting of the entire amount of the organic substance. When the all-inorganic coating agent of 1) is used, it is possible to obtain a magnetic steel sheet having excellent heat resistance and weldability, but the punching property and the adhesion are remarkably poor. When the all-organic coating agent of 3) is used, it is possible to obtain a magnetic steel sheet having good punchability and adhesiveness, but there is a problem that heat resistance and weldability are poor. It is proposed to use the semi-organic component type coating agent of 2) to complement the above-mentioned drawbacks.

Furthermore, recently, measures for improving the above various insulating film forming methods have been proposed. For example, as a method for controlling the surface shape of a steel plate punched or cut into a predetermined shape, Japanese Patent Laid-Open No. 52-33846 discloses one or more kinds of phosphoric acid-based and chromic acid-based materials and an organic resin. In forming the mixed coating, the organic resin particles are added to the treatment liquid to form an electric insulating coating having a surface roughness of 2 to 10 μmHmax and excellent punchability and weldability. A method has been proposed in which the organic resin particles (1) are added to a conventional emulsion resin in advance, uniformly dispersed, mixed with an inorganic substance, and coated and baked on the surface of a steel sheet. Thereby, the surface roughness becomes rough, the air permeability at the time of welding is improved, and good weldability is obtained.

Further, JP-A-61-183479 discloses an inorganic solution consisting of one or more kinds of phosphoric acid type and chromic acid type, and an organic resin particle powder having a particle diameter of 2 to 50 μm. A mixture with an emulsion resin solution that has been added and dispersed in advance is applied to the surface of a magnetic steel sheet and baked, and the surface of the magnetic steel sheet has a surface roughness of 0.5 to 1.5 μm, which is excellent in punchability, weldability, and insulation. In the method for forming an electric insulating coating, a method for surface treatment of electromagnetic steel sheet has been proposed, characterized in that the particles of the organic resin are surface-treated with a dispersibility improver before being added to the emulsion resin solution. .
It is stated that this makes it possible to obtain a non-oriented electrical steel sheet having good punchability and excellent weldability and heat resistance.

Further, Japanese Patent Laid-Open No. 3-240970 discloses a method for producing a non-oriented electrical steel sheet having excellent coating properties after strain relief annealing, in which 100 parts by weight of CrO ₃ and Al, M are used.
Acrylic, styrene, vinyl acetate and / or a copolymer thereof in which one or more oxides selected from g, Ca and Zn are adjusted to 20 to 40 parts by weight and the particle diameter is adjusted to 0.2 to 0.5 μm. 10 to 60 parts by weight of a fine particle emulsion solution of one or two or more kinds of resin consisting of, methylmethacrylate, polyacrylonitrile, polystyrene, cellulose, silicone, melamine, the particle diameter of which is adjusted to 1 to 50 μm.
It is disclosed that one or two or more of phenol, poval resin and / or a copolymer or cross-linked product thereof is applied in an amount of 2 to 30 parts by weight. As a result, punchability, weldability, and the like are excellent, particularly lubricity after strain relief annealing is excellent, and further, insulation and corrosion resistance are remarkably excellent.

However, in these conventional techniques, a fine particle emulsion resin having a particle diameter of 0.3 μm or less is used as a base resin, and any of them is used as a coarse particle resin to obtain surface roughness. A powdered resin having a coarse particle diameter is used for. Therefore, although the effect of the addition of the coarse particle resin has been obtained, the characteristics of the coating film are deteriorated due to the agglomeration of the resin powder at the time of the addition of the coarse particles and the non-uniformity and the poor wettability of the particles in the coating film. There is an unstable problem. Further, in order to improve heat resistance, weldability, etc., it is necessary to add a considerably large amount of coarse particle resin. As a result, the space factor may be significantly reduced and the coating appearance may be deteriorated.

From such a situation, regarding the semi-organic coating made of the organic-inorganic component, the surface shape is stably controlled, the punchability and the weldability are good, and the heat resistance of the coating is improved. Products having excellent lubricity, corrosion resistance, insulation, etc. after annealing are strongly desired by iron core processing manufacturers.

[0010]

DISCLOSURE OF THE INVENTION The present invention relates to a magnetic steel sheet which is excellent in the uniformity and adhesion of coating film components and whose surface shape is controlled by a coarse-grain emulsion resin. Non-oriented electrical steel sheet and its surface treatment applied to obtain its non-oriented electrical steel sheet, which have excellent properties such as punching property, weldability, sticking property, lubricity, scratch resistance, corrosion resistance, and insulation property. The purpose is to provide an agent.

[0011]

The gist of the present invention is as follows. That is, (1) one or more of epoxy, styrene, phenol, melamine, polyester, vinyl acetate, acryl, and silicone resin having a particle diameter of 0.5 to 3.0 μm as an organic substance on the surface of the electromagnetic steel sheet. And a treating agent containing at least one of chromates such as Al, Mg, Ca, and Zn as a main component are baked, and the surface roughness is an Ra value (center line roughness) of 0.15 to 0. A non-oriented electrical steel sheet having a 6 μm insulating coating formed thereon and a spherical projection formed on the surface of the coarse particle emulsion resin having a diameter of 3 μm or less and a height of 3 μm or less, and (2) As an organic substance, a particle size of 0.5 to
One or two or more 100 parts by weight of 3.0 μm of epoxy, styrene, phenol, melamine, polyester, vinyl acetate, acryl, silicone emulsion resin, A
Non-directionality consisting of 100 to 800 parts by weight of a chromate material selected from 1, 1, Mg, Ca, Zn, etc. as CrO ₃ and 30 to 250 parts by weight of one or more boric acid and borate materials. It is a surface treatment agent for electromagnetic steel sheets.

The present invention will be described in detail below. The inventors of the present invention, as a need of consumers who perform iron core processing using a non-oriented electrical steel sheet in recent years, are disadvantages when using a conventional organic-inorganic coating treatment agent, weldability and after annealing. Enormous experiments and research were conducted to improve the film lubricity and corrosion resistance of the film. As a result, we have succeeded in developing a technology that can solve all of the above-mentioned problems among customers of organic-inorganic coating treatment agents, which could not be solved even by the conventional improvement technology. That is, in the present invention,
As a base resin, a fine particle emulsion resin having a particle diameter of about 0.2 μm, which has been applied in the prior art, is used, and the particle diameter is 0.5 to 3.0 μm, which has not been considered in the conventional technology of using an emulsion resin. We have developed an application technology for emulsions with different particle sizes. Thereby, the uniformity of the liquid composition and the good coatability on the steel sheet were obtained. This has led to the realization of a technique capable of stably obtaining a uniform spherical projection shape as well as the uniformity and adhesion of the coating composition on the steel sheet after the baking treatment. As a result, an enormous amount of research and experiments have been conducted on technologies that are excellent in punchability before annealing, weldability, etc., and that can satisfy lubricity, corrosion resistance, insulation, etc. As a result, it has been successfully developed.

The first feature of the present invention is that the organic resin
In the inorganic component, as an organic resin, a particle size of 0.5 to
Epoxy, styrene, phenol, adjusted to 3.0μ
It is characterized by using melamine, polyester, vinyl acetate, acrylic, and silicone emulsion resin. Second
As an inorganic substance, one or more chromates selected from Al, Mg, Ca, Zn and the like are added and blended in a ratio of 100 to 800 parts by weight with respect to 100 parts by weight of the coarse particle emulsion. . As the third component, one or more kinds of boric acid and borate are added and blended in an amount of 30 to 250 parts by weight with respect to 100 parts by weight of the coarse particle emulsion. In these mixed liquids, the coarse particle emulsion resin of the present invention has a very good dispersibility with other components and forms a uniform solution phase. Therefore, the surface of the heat-resistant emulsion coarse-grain resin is uniformly covered with chromate and borate.
Then, at the time of coating and baking, the particle diameter of the coarse-grain emulsion is hardened to uniformly disperse it on the surface of the steel sheet to form fine projections in which the organic resin is wrapped with an inorganic component.

Due to such coating composition and surface shape effect, a coating having excellent punchability and weldability is formed, and the coarse particle emulsion resin covered with an inorganic component is subjected to heat treatment such as strain relief annealing. It does not decompose or disappear, and maintains the shape before annealing while maintaining the protrusions by the inorganic-organic reaction product on the surface. As a result, a film having excellent lubricity, insulating properties, corrosion resistance, adhesion, etc. is formed even after annealing. Such an effect is not seen at all when a normal fine particle emulsion resin is used, and is a characteristic when a coarse particle heat resistant resin as in the present invention is applied. The technique of applying coarse particle resin powder to the emulsion resin cannot obtain the uniformity, coatability and curing stability of the coating film as in the present invention.

The reason why it is preferable to limit the kind of the processing liquid used in the present invention, the mixing ratio and the processing conditions within the above ranges is as follows. The coarse particle emulsion, which is one of the main components applied to the present invention, has a particle size of 0.5 to 3.0 μm.
It is a coarse particle like m which was not expected in the prior art. As the component, one kind or two kinds or more of epoxy, styrene, melamine, polyester, vinyl acetate, acryl and silicone resin is used. As these resins, copolymers, cross-linked products and the like may be used.
Thus, the particle size of the emulsion resin is the most important factor in the present invention, and as shown in FIG.
When the thickness is less than μm, it is difficult to obtain the results of uniform spherical projections on the surface, the improvement of heat resistance, and the filling of the coating as in the present invention. On the other hand, when it exceeds 3.0 μm, the surface roughness of the steel sheet after baking becomes too rough, and the space factor is deteriorated as in the case of adding coarse powder particles disclosed in the prior art, or the iron core after the iron core is deteriorated. This is not preferable because there is a problem that particles in the coating film fall off in the processing step. Further, it is also limited by the problems of sedimentation and wettability of emulsion particles. It is 0.7 to 1.2 μm that is comprehensively excellent in terms of coating properties, workability, and the like.
As the resin component, the above-mentioned composition is suitable, and by applying the technique of coarsening particles, punching property, weldability and the like, as well as the effect of improving heat resistance during strain relief, can be obtained remarkably.
Other than these resin components, the above-mentioned improvement effect cannot be obtained even by applying the coarse-grain emulsion resin technique of the present invention.

Next, as the chromate used as the inorganic component, one or more chromates selected from Al, Mg, Ca, Zn and the like are CrO ₃ per 100 parts by weight of the resin component. As 100 parts by weight to 800 parts by weight. If the amount of the chromate is 100 parts by weight or less, the thickness of the chromate for obtaining the effect of coating the organic resin is insufficient, and sufficient heat resistance cannot be obtained even in the coarse particle emulsion technique of the present invention. On the other hand, if the amount is more than 800 parts by weight, the heat resistance is improved, but the organic content in all the coating components is reduced, and the workability such as punchability is deteriorated, which is not preferable. As the chromium compound, a compound having a dichromic acid composition is most preferable in view of problems such as stability and solubility of the liquid, and free CrO ₃ may be added if necessary.

Boric acid and borate are added in an amount of 30 to 250 parts by weight per 100 parts by weight of the resin emulsion. These act as a vitrification agent and a filler for the coating film, and the coating film can be densified and have a good appearance. If the addition amount is 30 parts by weight or less, these film densification effects cannot be obtained, while if the addition amount is 25
When the amount is 0 parts by weight or more, the solubility of these boric acid and boric acid compound is low, so that the dissolved state becomes unstable, which affects the appearance of the coating film and makes it difficult to control the solution. In applying the coating agent of the present invention, in order to improve the wettability of the emulsion resin, a surface active agent, a wettability improver, a reduction enhancer of a chromium compound and the like may be added for treatment.

Next, the reason why the present invention has the effects of excellent punchability, excellent welding characteristics, and excellent film lubricity, insulation, corrosion resistance and the like after annealing will be described. In the present invention, a coarse particle emulsion resin and a chromium compound,
Uniform and fine spherical projections are dispersed and formed on the surface of the steel sheet by an inorganic component such as a boric acid compound. This uniform and fine surface shape control effect of the surface cannot be obtained by the addition of the powdery coarse particle resin as in the prior art.
A film having good weldability can be obtained. Further, when the heat-resistant component resin of the present invention is a coarse particle emulsion of 0.5 to 3.0 μm, the decomposition reaction of the resin component during heat treatment is suppressed by the size effect, and A per unit particle is
It is possible to obtain the effect of further improving the heat resistance by increasing the coating amount of an inorganic component such as a chromate such as 1, Mg, Ca, Zn or borate. FIG. 1 (a) shows a surface state before and after annealing when a styrene resin having a particle diameter of 0.8 μm is used as the coarse particle emulsion of the present invention, and FIG. 1 (b) shows an acryl having a particle diameter of 0.2 μm as a comparative example. The surface state before and after annealing when using a vinyl acetate resin is shown in a photograph observed by SEM, but as is clear by comparing the two, in the present invention, the size of the spherical projections on the surface of the steel sheet is before and after annealing. It does not change and the surface roughness does not change. These inorganic-organic compounds cause an appropriate filling action of the coating during the annealing period, and prevent the occurrence of cracks as seen in the conventional coating using the fine particle emulsion resin. As a result, even in the film properties after annealing, due to the film shape effect, hardness, denseness, etc.,
It is considered that new effects such as the lubricity of the coating, the insulating property and the corrosion resistance, which cannot be obtained by the conventional organic-inorganic coating, can be obtained.

[0019]

【Example】

[Example 1] A non-oriented electrical steel sheet coil having a plate thickness of 0.5 mm, which was heat-treated by a known method, had a composition shown in Table 1 having a particle size of 1
Applying a treatment agent, whose main component is emulsion resin, adjusted to μm, with a rubber roll type coating device, and a plate temperature of 350 ° C.
It was baked in. The coating amount at this time was 1.5 g / m ² in weight after baking. A sample is cut out from this coil and punched, welded and 750 ° C x 2 hours
The lubricity, corrosion resistance, and insulation properties of the film after strain relief annealing were investigated. The results are shown in Table 2.

[0020]

[Table 1]

[0021]

[Table 2]

As a result, the one according to the present invention has good pre-annealing properties such as punchability and weldability, and the coating properties after annealing are lubricity, corrosion resistance, insulation properties, etc. all in comparison with those of the comparative examples. Good results have been obtained. Particularly, when the amount of dichromate is 300 parts by weight or more with respect to 100 parts by weight of the resin component, a remarkable improvement effect was observed.

[Example 2] In the same manner as in Example 1, the plate thickness after finish annealing was 0.5 mm (the surface roughness Ra value of the original plate was 0.1).
As shown in Table 3, a coil of non-oriented electrical steel sheet of 3) is coated with a coating agent consisting of dichromate and boric acid, a resin in which the particle size of emulsion resin is changed, and baked at a plate temperature of 350 ° C. Made product. A sample was cut out from this steel sheet, and the film characteristics were investigated in the same manner as in Example 1. The results are shown in Table 4.

[0024]

[Table 3]

[0025]

[Table 4]

As a result, in the case of the present invention, the surface roughness is controlled according to the particle size of the base emulsion resin, and the roughness before annealing and the roughness after annealing hardly change in any of the cases. Good results were obtained with respect to the heat resistance, the lubricity of the film after annealing, the seizure resistance, and the like. On the other hand, when the conventional fine particle emulsion of Comparative Example 1 was used, both the weldability and the coating properties after annealing were higher than those of the present invention.
The result was remarkably inferior. Further, the comparative example 2 in which the roughness of the original plate is roughened and the conventional fine particle emulsion-based treatment agent is applied also has some effect on the weldability, but the lubricity and the seizure resistance after annealing are obtained. Etc. are all bad,
The result proves that the fine spherical projections produced by the emulsion of coarse particles as in the present invention produce a great effect.

[0027]

In the treatment agent and product to which the heat-resistant coarse particle emulsion and the inorganic component system of the present invention are applied, the technique of adding the conventional fine particle emulsion resin and the coarse particle powder resin as the heat resistance improver A film having a uniform film composition, which was not seen in the above, and having spherical projections uniformly and finely dispersed is obtained. The coating composition and the shape effect are matched to achieve both the properties before and after annealing. In particular, a product having excellent lubricity, scratch resistance, and corrosion resistance of the film after annealing can be obtained.

[Brief description of drawings]

FIG. 1 shows the state of the coating film on the steel sheet surface before and after strain relief annealing by SE.
3A is a photograph showing a grain structure observed in M, (a) is a surface state before and after annealing when a styrene resin having a grain diameter of 0.8 μm is used as a coarse grain emulsion of the present invention,
(B) shows the surface state before and after annealing when the acryl-vinyl acetate resin having a particle diameter of 0.2 μm of the comparative example is used.

FIG. 2 shows the particle diameter of the heat-resistant emulsion resin of the present invention and the scratch resistance of the steel sheet surface after annealing.

FIG. 3 is a schematic diagram of an apparatus for measuring the lubricity of a coating after annealing in FIG.

FIG. 4 is a method for measuring seizability during strain relief annealing, in which (a) is a state in which a laminated steel sheet is annealed after being tightened, (b)
FIG. 6 is a diagram showing a state in which a peeling load of a steel plate is measured by a spring balance.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kikuji Hirose 1 Fuji-machi, Hirohata-ku, Himeji-shi, Hyogo Shin Nippon Steel Corp. Hirohata Works

Claims (2)

[Claims] 1. One or two kinds of epoxy, styrene, phenol, melamine, polyester, vinyl acetate, acryl, and silicone emulsion resin having a particle diameter of 0.5 to 3.0 μm as an organic substance on the surface of a magnetic steel sheet. Above and Al, M
A treatment agent containing at least one of g, Ca, and Zn chromate as a main component is applied and baked, and the surface roughness is an Ra value (center line average roughness) of 0.15 to 0.6 μm. Insulating coating is formed, and the shape of spherical projections formed on the surface by emulsion resin has a diameter of 3 μm or less and a height of 3 μm.
A non-oriented electrical steel sheet having excellent coating properties, characterized by being m or less. 2. A particle size of 0.5 to 3.0 as the organic substance.
Al, M to 100 parts by weight of one or two or more kinds of μm epoxy, styrene, phenol, melamine, polyester, vinyl acetate, acrylic, silicone emulsion resin
Chromate material selected from g, Ca, Zn is Cr
A surface treatment agent for non-oriented electrical steel sheet having excellent coating properties, which comprises 100 to 800 parts by weight of O ₃ and 30 to 250 parts by weight of one or more of boric acid and borate substances.