JP3323375B2 - Electrical insulation coating method for electrical steel sheet with high space factor and excellent weldability, radiation resistance, and punchability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating an electrical insulating film of a magnetic steel sheet having a high space factor, excellent punching properties, excellent weldability, and excellent radiation resistance.

[0002]

2. Description of the Related Art When a non-oriented electrical steel sheet is used as a laminated core (iron core) of a transformer, a motor, or the like, a predetermined number of sheets are continuously punched, then a predetermined number of sheets are welded,
It is fixed by caulking or bonding to form a laminated iron core.

[0003] Generally, an electrical insulating film is formed on the surface of a non-oriented electrical steel sheet. This insulating film requires various film properties such as corrosion resistance, weldability, adhesion, heat resistance, etc., in addition to insulation properties. In particular, it is required that the space factor, punching property, and adhesion be excellent. Is done. Furthermore, when an iron core is used as an electrode or the like of a particle accelerator, the laminated iron core is also exposed to radiation for a long period of time, so that the insulating film is also required to have excellent radiation resistance.

Heretofore, as an electrical insulating film of a non-oriented electrical steel sheet, an inorganic, organic, or inorganic-organic mixed electrical insulating film has been known. However, inorganic insulating films are organic,
Compared to the inorganic-organic mixed insulating film, it has excellent radiation resistance and weldability, but is inferior in punchability. Further, organic insulating films and inorganic-organic mixed insulating films have excellent punching properties and adhesion, but are inferior in radiation resistance and weldability.

[0005] Inorganic-organic mixed insulating films are disclosed in
No. 6744, a phosphoric acid type or a chromic acid type is added to the surface of a steel sheet having a roughness of 20 Hr.m.sμinch or more.
There has been proposed an electromagnetic steel sheet for a laminated iron core having a mixed coating of a seed and an organic resin and having excellent punching properties and weldability. Japanese Patent Publication No. 49-19078 discloses a punching property in which a magnetic steel sheet has a coating having a surface roughness of 2 μHmax or more in which one or two of phosphoric acid and chromic acid and an organic resin are mixed. Electromagnetic steel sheets for laminated iron cores having excellent weldability have been proposed.

In recent years, there has been a strong demand for miniaturization and weight reduction of electric devices such as motors and transformers. For this reason, it is also required that laminated iron cores have good efficiency, which greatly affects efficiency. Moments are required. In addition, electromagnetic steel sheets for laminated iron cores used in radiation handling devices such as particle accelerators have not only a high space factor, excellent punching properties and weldability, but also characteristics that are not easily deteriorated by radiation irradiation, that is, resistance to radiation. It is necessary that radioactivity be excellent.

[0007]

However, the non-oriented electrical steel sheet having an electrical insulating film having excellent film characteristics disclosed in Japanese Patent Publication Nos. 49-6744 and 49-19078 is occupied by space occupation. Rate and radiation resistance. That is, when the non-oriented electrical steel sheet is used for an iron core such as a transformer as described above, after punching into a predetermined shape,
A predetermined number of sheets are stacked and usually fixed by welding to form a laminated iron core. In the method disclosed in the above-mentioned JP-B-49-6744 and JP-B-49-19078, an organic resin is compounded. It improves the punching properties and further improves the weldability by imparting roughness to the steel sheet surface.

However, in any of the methods, there is a problem that the space factor decreases due to an increase in the surface roughness, and the magnetic characteristics of the laminated iron core deteriorate. In addition, since organic resin is more susceptible to radiation irradiation damage than inorganic materials, non-oriented electrical steel sheets used for laminated iron cores used in radiation handling facilities such as particle accelerators have traditionally used inorganic insulating coatings. Has been given. However, the inorganic insulating film has a problem that the punching property is inferior as described above.

The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have applied a processing solution in which a polyfunctional epoxy resin is blended in a specific ratio to a chromic acid-based solution to a specific surface roughness or less. It has been found that such problems can be solved by drying, and the present invention has been completed.

[0010]

The present invention for solving the above problems is as follows. That is, a ferrite having three or more epoxy groups in the main skeleton per one part by weight of a metal chromate salt (in terms of CrO ₃ ) is formed on the surface of a magnetic steel sheet.
Nol novolak type, ortho-cresol novolak type epoxy resin emulsion (in terms of resin solid content)
After a processing liquid mainly containing 01 to 5.0 parts by weight is applied thinly and uniformly, the surface roughness is Ra (center line average roughness) of 1.
This is a method for treating an electrical insulating film of an electromagnetic steel sheet having a high space factor characterized by baking to 0 μm or less, and having excellent punching properties, weldability, and radiation resistance.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the contents of the present invention will be described in detail. (Inorganic compound used in the present invention) Chromic acid metal salt in the present invention is calcium, magnesium, zinc or other dichromate or chromic anhydride calcium, magnesium,
In the present invention, a divalent oxide, hydroxide or carbonate such as zinc or the like, in which one or more selected from the above metal salts are dissolved is used. In order to stabilize the treatment liquid, it is preferable to dissolve one or more of divalent metal oxides, hydroxides, and carbonates in a substantially saturated state or a supersaturated state.

[0012] [invention in use to Rue epoxy resin emulsion] Usually, typical epoxy resin which was reacted with bisphenol A and epichlorohydrin, have a 2 groups epoxy groups per molecule, bisphenol A type bifunctional is a epoxy resin, and the Rue port <br/> carboxymethyl resin emulsion be used in the present invention, an organic resin having a main skeleton monomer or highly reactive epoxy group or 3 groups in the oligomer molecule called Is emulsified. Examples of such a type of epoxy resin include a phenol novolak type and an orthocresol novolak type.

The development of epoxy resins has been remarkably progressed in recent years. In the process, various modifications have been carried out according to the purpose of use, and an extremely large variety of epoxy resins have been developed. It is essential that the epoxy resin has three or more epoxy groups in the main skeleton, and ordinary bifunctional epoxy resins cannot obtain predetermined characteristics.

The method of emulsification is not particularly limited.
These epoxy resins are produced by a usual emulsification method in the presence of an emulsifier. Alternatively, a self-dispersion type in which a hydrophilic group such as a hydroxyl group is introduced into the epoxy resin skeleton may be used.

[Blending ratio] A polyfunctional epoxy resin emulsion (converted to resin solid content) is used in an amount of 0.01 to 5.0 per 1 part by weight of a metal chromate (converted to CrO ₃ ).
The reason for limiting to parts by weight is that if it is less than 0.01, sufficient punching properties and adhesion of the film itself cannot be obtained, and if it is more than 5.0, the stability of the processing solution is inferior, and the viscosity increases, A uniform film cannot be obtained easily. It is essential that the treatment liquid in the present invention contains the two components described above. In addition, a reducing agent such as ethylene glycol, a glass forming agent such as boric acid and colloidal silica, a nonionic interface A dispersibility improver such as an activator may be added.

[Treatment method] This is a method of applying and baking a treatment liquid. A predetermined amount of the treatment liquid is applied by a roll coater or the like.
It is only necessary to bake at a baking temperature of 0 ° C. to 700 ° C. for a short time.

[Amount of Coating] The amount of the insulating film formed on the surface of the magnetic steel sheet is not particularly limited, but may be 0.5 g / m ^{2 to} 5 g.
/ Range of m ² is not sufficient punching property can be obtained in less than suitable and 0.5 g / m ^2, whereas at the time of coating and drying exceeds 5 g / m ² there is a risk of peeling of the insulating film, the space factor Is also inferior.

[Surface Roughness] In the present invention, the surface roughness is defined as Ra
(Center line average roughness) is limited to 1.0 μm or less.
This is because when the thickness is 1.0 μm or more, the space factor significantly decreases, and the efficiency of the laminated iron core is inferior. Above 49
In the method disclosed in JP-A-19078, a decrease in the space factor is inevitable to impart roughness to the steel sheet surface in order to improve the weldability, but in the present invention, it will be described in the section of [Action]. For that reason, it is not necessary to impart roughness, and a high space factor can be obtained. Although some means for controlling the surface roughness are known, in the present invention, the surface roughness of 1.0 μm or less is achieved by controlling the surface roughness of the steel sheet itself.

As described above, the organic resin emulsion used in the present invention is a polyfunctional epoxy resin emulsion, and the amount of the organic resin emulsion is based on 1 part by weight of a metal chromate salt (in terms of CrO ₃ ). The surface roughness is limited to 0.01 to 5.0 parts by weight, and the surface roughness is limited to 1.0 μm or less in terms of Ra (center line average roughness). Under these conditions, an electrical insulating film having a high space factor and extremely excellent punching properties, weldability and radiation resistance can be obtained.

[0020]

According to the present invention, the main skeleton is used as an emulsion resin.
By using an epoxy resin having three or more epoxy groups, excellent punching properties are maintained as characteristics of the organic-inorganic mixed film. Furthermore, this epoxy resin is excellent in heat resistance, and it is presumed that even when exposed to a high temperature during welding, generation of welding gas due to decomposition of the resin is small, and generation of blow holes is suppressed.

Therefore, the surface roughness is small and the distance between the plates of the laminated iron core is small, so that the welding gas generated when welding the conventional organic / inorganic mixed film is not sufficiently dissipated, and a small gap that generates a blow hole is generated. Therefore, it is considered that the welding gas is satisfactorily dissipated and exhibits excellent weldability.

Although the reason why the present invention improves the radiation resistance is not well understood, the epoxy resin itself is an organic resin having excellent radiation resistance. It is presumed that the radiation resistance of the entire film is improved by improving the characteristics of the organic resin having a low value.

[0023]

Next, examples of the present invention and comparative examples will be described.
Electrical steel sheet (containing 2.0% Si, thickness 0.5 mm, Example 1
, 2 and Comparative Examples 1 to 3 were each coated with the treatment liquid shown in Table 1 on the surface having a surface roughness Ra of 0.40 μm, and Comparative Examples 4 and 5 were squeezed with a rubber roll. It baked for 60 seconds in the annealing furnace set to ° C. Note that the resin emulsion concentration was all 50%.

[0024]

[Table 1]

Table 2 shows the results of the above Examples and Comparative Examples. As is clear from Table 2, according to this example, an electrical insulating film having a high space factor, excellent punching properties, and radiation resistance was obtained.

[0026]

[Table 2]

[Evaluation of radiation resistance]
Irradiation with β-rays was performed, and the deterioration of the insulating film was evaluated based on the change in gloss before and after the irradiation.

[0028]

As described in detail above, according to the method of the present invention, it is possible to obtain an electrical steel sheet having an electrical insulating film having a high space factor and excellent punching properties and radiation resistance.

Claims (1)

(57) [Claims] A metal chromate (C)
₃ parts or more in the main skeleton per 1 part by weight (in terms of rO ₃ )
Phenol novolak type having epoxy group above, or
A socresol novolak type epoxy resin emulsion (converted to resin solid content) is applied thinly and uniformly to a processing solution containing 0.01 to 5.0 parts by weight as a main component, and then the surface roughness is Ra (center line average roughness). Has a high space factor characterized by baking to 1.0 μm or less in
An electrical insulation coating treatment method for electromagnetic steel sheets with excellent radiation resistance.