JPH06101058A - 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 as film properties after being subjected to stress relieving anealing as well as excellent in punching properties, weldability or the like. CONSTITUTION:A steel sheet is coated with a treating agent essentially consisting of, as organic substance, one or >= two kinds among styrene, epoxy, phenol, melamine, polyester, vinyl acetate, acrylic, silicone series emulsion resin contg. at least >=50% styrene series and/or epoxy series resin and one or >=two kinds among the chromates of Al, Mg, Ca, Zn or the like, and baking is executed. In this way, the grain-oriented silicon steel sheet excellent in film properties and in which an insulated film having 0.15 to 0.6mum surface roughness by Ra value is formed and the shape of spherical projection formed on the surface by coarse-grained emulsion resin 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 insulating property but also excellent in punching property, adhesiveness, heat resistance and oil resistance, and lowers the space factor of the magnetic steel plate. It is required to have the property of not being present. Further, as a special case, when the iron core for a transformer has a self-laminating step again after being annealed like the EI core, the slipperiness of the steel sheet surface influences the work efficiency during lamination. Therefore, it is also important that the insulating coating of the product is excellent in slipperiness, scratch resistance and the like.

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 type and chromic acid type and an organic resin. In forming a mixed coating, organic resin particles are added to the treatment liquid to form an electrical insulating coating having a surface roughness of 2 to 10 μmHmax and excellent punchability and weldability. A method has been proposed in which organic resin particles are used, which 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, in Japanese Patent Laid-Open No. 61-183479, 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 are previously disclosed. A mixed solution of the added and dispersed emulsion resin solution is applied to the surface of the magnetic steel sheet and baked, and the surface of the magnetic steel sheet has a surface roughness of 0.5 to 1.5 μm and is excellent in punchability, weldability and insulation. In a method for forming an electric insulating coating, a surface treatment method for electromagnetic steel sheets has been proposed, which comprises subjecting the particles of the organic resin to a surface treatment 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 adding coarse particle resin has been obtained, the problem is that agglomeration of the resin powder at the time of adding coarse particles and the resulting non-uniformity of particles in the coating film and poor wettability to the steel sheet. for,
There is a problem that the coating properties are not stable. Furthermore, 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) on the surface of the electromagnetic steel sheet, as an organic substance, having a particle diameter of 0.5 to 3.0 μm,
At least 50 styrenic and / or epoxy resin
% Or more of styrene, epoxy, phenol, melamine, polyester, vinyl acetate, acryl, one or more kinds of silicone resins and one or more kinds of chromates such as Al, Mg, Ca and Zn. The treating agent as the main component is baked, and the surface roughness is Ra value (center line average roughness) of 0.1.
Insulating film having a thickness of 5 to 0.6 μm is formed, and the shape of spherical projections formed on the surface of the coarse particle emulsion resin is 3 μm or less in diameter and 3 μm or less in height. An excellent non-oriented electrical steel sheet, and (2) an organic substance having a particle diameter of 0.5 to 3.0 μm,
At least 50 styrenic and / or epoxy resin
% Or more of styrene, epoxy, phenol, melamine, polyester, vinyl acetate, acryl, silicone emulsion resin, or 100 parts by weight of two or more of them.
One or two or more chromate substances selected from Al, Mg, Ca, Zn and the like are used as CrO _{3 and} are 100 to 80.
30 parts by weight of 0 part by weight and one or more of boric acid and borate substances
It is a surface treatment agent for non-oriented electrical steel sheets consisting of ˜250 parts by weight.

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 replaced with a particle diameter of 0.5 to 3 which is beyond common sense as a conventional application technology of emulsion resin. A technique for applying an emulsion of coarse particles of 0.0 μm was developed. Thereby, the dispersibility of the coarse particle resin in the liquid composition and the good coatability on the steel sheet were obtained. Furthermore, a technique for applying a resin containing at least 50% or more of styrene and / or epoxy resin as a resin component has been developed. 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, punching properties before annealing, weldability, etc., which were considered unrealizable with conventional technology, were excellent, and lubricity after corrosion, corrosion resistance,
As a result of extensive research and experiments, we have succeeded in developing a technology that can satisfy all of the insulation properties.

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
It is characterized by using styrene, epoxy, phenol, melamine, polyester, vinyl acetate, acryl, and silicone emulsion resin containing 50% or more of styrene and / or epoxy resin adjusted to 3.0 μm. Secondly, as inorganic substances, Al, Mg, C
One or two or more chromate salts selected from among a, Zn, etc. per 1 part by weight of the coarse particle emulsion.
It is added and blended at a ratio of 00 to 800 parts by weight. 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 very good dispersibility with other components and forms a uniform solution phase. Therefore, styrene and /
Alternatively, the surface of the coarse-grained resin composed of a heat-resistant resin mainly containing an epoxy resin is uniformly covered with chromate, boric acid, borate, or the like. At the time of coating and baking, due to the particle size effect of the coarse-grained emulsion, it is uniformly dispersed 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 a coating composition and surface shape effect, a coating having excellent punchability and weldability is formed, and further, coarse particle emulsion particles mainly composed of styrene and / or epoxy resin covered with an inorganic component. Does not decompose or disappear even by heat treatment such as strain relief annealing due to the grain size effect and heat resistance due to the resin component, and maintains the projections due to the inorganic-organic reactant on the surface while maintaining the shape before annealing. To do. As a result, even after annealing, a coating film that is remarkably excellent in lubricity, insulation, corrosion resistance, adhesion, etc. is formed. Such an effect is not seen at all when using a normal fine particle emulsion resin,
This is a feature when heat-resistant styrene and / or epoxy-based resin having coarse particles as in the present invention is applied. In addition, the technique of adding coarse particle resin powder to fine particle emulsion resin, which is found in the prior art, does not provide the effect of stabilizing the uniformity and coating property 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.
Like m, it is a coarse particle that was not expected even by the conventional emulsion resin application technology. As its component, at least styrene and / or epoxy resin is used.
One or more of epoxy, styrene, melamine, polyester, vinyl acetate, acrylic, and silicon-based resin containing 0% or more are used. As these resins, those such as copolymers and crosslinked products of the above resin group may be used. The particle size of the emulsion resin is the most important factor in the present invention, and when the particle size is 0.5 μm or less as shown in FIG. , It is difficult to obtain the filling result of the coating. On the other hand, 3.0
When the thickness is more than μm, the surface roughness of the steel sheet after baking becomes too rough, and the space factor deteriorates as in the case of adding coarse powder particles disclosed in the prior art, or the film is not formed in the coating film in the subsequent core processing step. This is not preferable because there is a problem that the particles of (3) fall off. Further, it is also limited by problems such as sedimentation and wettability of emulsion particles or manufacturing cost. The overall superiority in terms of coating properties, workability, etc. is 0.7-1.2 μm
Is. As the resin component, at least styrene and / or
Alternatively, it is important that the above-mentioned composition resin contains 50% or more of an epoxy resin. By applying the above-described particle coarsening technique, punching properties, weldability, and the like, as well as a heat resistance improving effect during strain relief, can be remarkably obtained. Styrene and / or epoxy resin is 50% in these resin components
If the amount is less than that, it cannot be said that the heat resistance is particularly good, and it is difficult to obtain the effect of improving the lubricity, insulating property, corrosion resistance and the like after annealing.
When it is 50% or more, these remarkable improving effects are obtained. 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. When the chromate content is 100 parts by weight or less, the chromium compound for obtaining the surface coating effect of 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 effect of improving the heat resistance is increased, but the ratio of the organic components in all the coating components is decreased and the workability such as punching property is deteriorated, which is not preferable. As the chromium compound, the one having a dichromic acid composition is the best from the viewpoint of problems such as stability and solubility of the liquid,
If desired, free CrO ₃ may be added.

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 250
Since the solubility of boric acid and the boric acid compound is low when the amount is more than 10 parts by weight, the dissolution 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, etc. after annealing will be described. In the present invention, a uniform and fine spherical projection is dispersed and formed on the surface of the steel sheet by a coarse particle emulsion resin containing 50% or more of styrene and / or epoxy resin as an ingredient and an inorganic ingredient such as a chromium compound and a boric acid compound. The effect of controlling the uniform and fine surface shape of the surface cannot be obtained by the addition of the powdery coarse particle resin as in the prior art, and a film having excellent punchability and weldability can be obtained. When the styrene and / or epoxy-based component resin is made into a coarse particle emulsion having a particle size of 0.5 to 3.0 μm as the heat-resistant main component of the present invention, the heat resistance of the resin component itself is improved and the heat treatment is performed. In addition to suppressing the decomposition reaction of the resin component due to the size effect, Al, Mg, C per unit particle
The coating amount of the inorganic component such as chromate or borate such as a and Zn is increased, and the effect of further improving the heat resistance can be obtained.
Therefore, as shown in FIGS. 1A and 1B, the size of the spherical projections on the surface of the steel sheet does not change and the surface roughness does not change before and after annealing. These inorganic-organic compounds cause an appropriate filling action of the coating during the annealing period, and crack formation as seen in the conventional coating using the fine particle emulsion resin (shown in FIGS. 2 (a) and 2 (b)). Prevent. As a result, even with respect to the film characteristics after annealing, due to the shape effect, hardness, denseness, etc. of the film, as shown in FIG. It is considered that new effects that were not obtained can be obtained.

[0020]

【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
A treatment agent having an emulsion resin as a main component adjusted to μm was applied by a rubber roll type application device, and baking treatment was performed at a plate temperature of 350 ° C. The coating amount at this time was 1.2 g / m ² in terms of weight after baking. A sample was cut out from this coil, and punching property, weldability, and lubricity, corrosion resistance, and insulation property of the coating film after strain relief annealing at 750 ° C. × 2 Hr were investigated. The results are shown in Table 2.

[0021]

[Table 1]

[0022]

[Table 2]

As a result, according to the present invention, the pre-annealing properties such as punching property and weldability are good, and the coating properties after annealing are lubricity, corrosion resistance, insulation properties, etc. all in comparison with 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 (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.

[0025]

[Table 3]

[0026]

[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, and the welding is not performed. 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, the weldability and the coating properties after annealing were significantly inferior to those of the present invention. 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. The above results are all bad, and the results prove that the fine spherical projections produced by the emulsion of coarse particles produce a large effect as in the present invention.

[0029]

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 With a uniform coating composition that could not be realized at all, a coating having spherical projections uniformly and finely dispersed can be 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 a coarse particle emulsion of the present invention having a particle size of 0.
It is the photograph which shows the grain structure which observed the coating film of the steel plate surface at the time of using 8 micrometer styrene resin by SEM,
(A) shows the state before the stress relief annealing and (b) shows the state after the annealing.

FIG. 2 is a photograph showing a particle structure of a coating film on the surface of a steel sheet observed by SEM when an acrylic-vinyl acetate resin having a particle diameter of 0.2 μm is used as a comparative example, and (a) is a strain relief annealing. Before, (b) shows the state after annealing.

FIG. 3 shows the particle size of the heat resistant emulsion resin of the present invention and the scratch resistance of the steel sheet surface after annealing.

FIG. 4 is a schematic diagram of an apparatus for measuring the lubricity of a coating after annealing in FIG.

FIG. 5 is a method for measuring seizure during strain relief annealing, in which steel plates are laminated as shown in (a), and a tightening pressure of 40 kg /
After tightening at cm ² , 750 ° C × 2 Hr annealing is performed (b)
The peeling load of the steel sheet was measured with a spring balance as shown in FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyoji Hirose 1 Fuji-machi, Hirohata-ku, Himeji-shi, Hyogo Prefecture Inside Nippon Steel Works Hirohata Works (72) Inventor Kazutoshi Takeda Fuji, Hirohata-shi, Himeji-shi, Hyogo Prefecture No. 1 town Shin Nippon Steel Co., Ltd. Hirohata Works

Claims (2)

[Claims] 1. Styrene, epoxy, phenol, melamine containing at least 50% or more of either or both of a styrene-based resin and an epoxy-based resin having a particle diameter of 0.5 to 3.0 μm as an organic substance on the surface of a magnetic steel sheet. , Polyester, vinyl acetate, acrylic, silicone emulsion resin 1
, Or two or more and a treating agent containing one or more of Al, Mg, Ca, and Zn chromates as main components are applied and baked, and the surface roughness is Ra value (center line average roughness). At 0.1
An insulating film having a thickness of 5 to 0.6 μm is formed, and the shape of spherical projections formed on the surface of the coarse-grain emulsion resin has a diameter of 3 μm or less and a height of 3 μm or less. Non-oriented electrical steel sheet. 2. A particle size of 0.5 to 3.0 as the organic substance.
styrene, epoxy containing at least 50% or more of either or both of a styrene type resin and an epoxy type resin of μm,
1 or 2 or more of phenol, melamine, polyester, vinyl acetate, acrylic and silicone emulsion resin 1
Chromic acid selected from Al, Mg, Ca, Zn, or one or more kinds of chromate substances as CrO ₃ per 100 parts by weight, and 100 to 800 parts by weight of boric acid, 1 of borate substances. A surface treatment agent for non-oriented electrical steel sheets having excellent coating properties, which comprises 30 to 250 parts by weight of one kind or two or more kinds.