JP2944849B2 - Method for producing non-oriented electrical steel sheet with extremely good coating properties - 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 an electromagnetic steel sheet which maintains a high space factor and excellent weldability, punching properties and adhesion, and exhibits excellent slip properties after strain relief annealing. It is.

[0002]

2. Description of the Related Art As is well known, when non-oriented electrical steel sheets are used for iron cores such as motors and transformers, they are punched into a predetermined shape and then subjected to strain relief annealing. It is made into an iron core by bonding or the like. Usually, an electrical insulating coating is formed on the surface of the non-oriented electrical steel sheet. This insulating coating is not only insulating,
Various coating properties such as corrosion resistance, weldability, adhesion, and heat resistance are required, and particularly, excellent space factor, punching property, and adhesion are required. In addition, it is important not only that the insulating property is maintained after the strain relief annealing, but also that the corrosion resistance is excellent. Furthermore, in recent years, a steel sheet having good slipperiness after strain relief annealing has been required due to the problem of lamination of the iron core.

Conventionally, inorganic, organic, and mixed inorganic-organic insulating films have been known as electric insulating films for non-oriented electrical steel sheets. However, the inorganic insulating coating film has excellent heat resistance and slipperiness after strain relief annealing, but is inferior in punching properties, as compared with organic or inorganic-organic mixed systems. On the other hand, the organic insulating coating has excellent punching properties and adhesion, but the coating is decomposed and destroyed by the strain relief annealing, and the adhesiveness after strain relief is poor, so that it cannot be used. As the inorganic-organic mixed insulating coating, Japanese Patent Publication No. 50-15013 discloses a treatment solution containing a dichromate and an organic resin emulsion such as vinyl acetate, butadiene-styrene copolymer, and acrylic resin as main components. A method of forming an insulating film is proposed that maintains a high space factor, excellent adhesion, punching properties, etc. by forming an insulating film by using it, and obtains fairly good film characteristics even after performing strain relief annealing. Have been.

[0004]

By the way, the non-oriented electrical steel sheet having an electrical insulating coating having excellent coating properties disclosed in Japanese Patent Publication No. 50-15013 is characterized in that it has a sliding property after strain relief annealing. The properties and heat resistance are not sufficient, and further improvement has been desired. As described above, when using a non-oriented electrical steel sheet for an iron core of a motor or the like, after punching into a predetermined shape, performing strain relief annealing, stacking a predetermined number of pieces, welding, caulking or fixing by bonding or the like. Although it is considered to be an iron core, this manufacturing process has recently
It is important that the steel sheet after the strain relief annealing has good slipperiness on the guide during the laminating process and good slipperiness between the steel sheets after automation is advanced. If the slipperiness is poor, the steel sheet does not move smoothly on the guide during the manufacturing process, the steel sheet surface is scratched, or the coating peels off. on the other hand,
When the cross section of a predetermined number of punched plates is adjusted by an automatic straightening machine at the time of lamination on an iron core, if the slipperiness is poor, the cross section of the punched plate is damaged or the hip is broken. In addition, due to the problem of insufficient heat resistance, deterioration of iron core characteristics due to rust during use of the annealed material also becomes a problem.

Further, these conventional insulating coatings for non-oriented electrical steel sheets use a chromium compound as a coating component as seen in the use of dichromate. For this reason, in recent years, in which the environmental problem is severe in the manufacturing process of the magnetic steel sheet or the consumer of the magnetic steel sheet, development of an insulating coating treatment technology that does not contain a chromium compound has been demanded.

The present invention provides an electric insulating coating having excellent coating properties disclosed in the above-mentioned Japanese Patent Publication No. 50-15013 by using a treating solution containing no chromium compound and improving an inorganic component and an organic resin component. An object of the present invention is to provide a processing method that solves the difficulties found in non-oriented electrical steel sheets having a high space factor and provides excellent weldability, punchability, and excellent slip properties after strain relief annealing.

[0007]

SUMMARY OF THE INVENTION The inventors of the present invention have found that in the case of the above-mentioned conventional insulating coating formed of a chromate-emulsion type resin, the insulating coating component deteriorates due to strain relief annealing. It was found that the slip property after annealing was reduced. In addition, in the iron core processing process at the customer, the chromate film was focused on the importance of the development of the chromeless film in improving the working environment. Therefore, the present inventors have conducted research on the emulsion resin and the film structure. As a result, instead of the conventional chromic acid-based inorganic substance, Al phosphate was used as a main component, and the particle diameter of the emulsion resin was 0.5.
By using a special emulsion resin of up to 3.0 µm, it is chrome-less and has excellent heat resistance in strain relief annealing,
The present inventors have found that the corrosion resistance and the slipperiness are remarkably improved, and completed the present invention.

That is, the gist of the present invention is as follows. (1) As a main component, 100 parts by weight of a first phosphate solution of Al and 1 to 300 parts by weight of an organic resin emulsion having a particle diameter of 0.5 to 3.0 μm are converted into a solid content on the surface of an electromagnetic steel sheet. A method for producing a non-oriented electrical steel sheet having extremely good coating characteristics, characterized in that a treatment liquid is uniformly applied and then baked. (2) 100 parts by weight of a first phosphate solution of Al, 1 to 20 parts by weight of boric acid and 1 to 50 parts by weight of colloidal silica, and a particle size of 0 to 100 parts by weight in terms of solid content on the surface of the magnetic steel sheet. It was uniformly apply the treatment solution mainly composed of an organic resin emulsion 1-300 parts by weight of .5 ～3.0Myuemu, characterized in that the baking, the production of very good non-oriented electrical steel sheet coating properties Method. (3) In the above (1) and (2), the organic resin emulsion is formed of acrylic, polystyrene, vinyl acetate, silicon, polyethylene, polypropylene, polyamide,
A method for treating an insulative coating of a non-oriented electrical steel sheet having extremely good coating characteristics, characterized in that at least one selected from the group consisting of polycarbonate, melamine, phenol, polyurethane, alkyd, isocyanate and epoxy resin is used.

Hereinafter, the contents of the present invention will be described in detail. [Inorganic compound used in the present invention] Al phosphate plays an important role as a film forming agent having excellent heat resistance. Further, when mixed with another coating agent, it has a large function as a binder and has a large ability to form a film at a low temperature, so that it is used as a main component in the present invention. The primary phosphate of Al referred to in the present invention is a reaction product of an Al compound such as Al (OH) ₃ or Al ₂ O ₃ and phosphoric acid (H ₃ PO ₄ ), and is usually called primary aluminum phosphate. It is an aqueous solution of a compound having a composition of Al (H ₂ PO ₄ ) ₃ . At this time, the molar ratio of Al ₂ O ₃ / H ₃ PO ₄ in the solution is 0.13 to 0.20. If the molar ratio is smaller than 0.13, the amount of free phosphoric acid increases, so that the seizure at the time of strain relief annealing increases and the hygroscopicity increases, which is not preferable. This is not preferable because the properties deteriorate and precipitation occurs in a solution. In the present invention, one or two kinds of boric acid (H ₃ BO ₃ ), colloidal silica and the like are used as necessary. Both boric acid and colloidal silica increase the heat resistance of the coating, in addition to increasing the density of the vitrified coating, increasing the surface gloss, and the like.

[Resin Emulsion Used in the Present Invention] In the present invention, a resin emulsion having a particle size of 0.5 to 3.0 μm is used. The types of emulsion resins include acrylic, polystyrene, polypropylene, polyarimide,
Resins such as polycarbonate, melamine, phenol, polyurethane, alkyd, isocyanate, and epoxy can be used. Emulsions of these resins by an ordinary emulsification method in the presence of an emulsifier, and those having a particle size of 0.5 to 3.0 μm can be used in the present invention.
Particularly, among these, when an epoxy resin, a styrene resin, a phenol resin, and an acrylic resin are used, extremely excellent coating properties can be obtained. Particle size 0.5 μ
If it is less than m, the effects of the shape effect of the fine spherical projections formed on the coating surface by the mixture with the phosphate, such as the improvement of the weldability, the insulation, the slipperiness, and the heat resistance, cannot be obtained. On the other hand, 3 [mu] m stability is poor of the particles in ultra the solution is limited to become industrially difficult to use.

[Blending ratio] The water-dispersible emulsion resin is added in an amount of 1 to 300 parts by weight based on 100 parts by weight of aluminum phosphate.
If the amount is less than 1 part by weight, sufficient punching properties and a dense surface film, gloss, etc. of the film itself cannot be obtained, while if it exceeds 300 parts by weight, the film peels off during strain relief annealing. This causes insufficient heat resistance.
In addition, the corrosion resistance after annealing and the lubricating properties of the coating deteriorate. The boric acid added as an inorganic component is monobasic Al phosphate;
It is 1 to 20 parts by weight with respect to 0 parts by weight. When the amount of boric acid is less than 1 part by weight, effects such as densification of the coating and improvement in heat resistance are not obtained. If the amount is more than 20 parts by weight, the solubility is low, so that precipitation occurs in a solution, and the heat resistance, insulation properties, and surface appearance improving effects are limited. Colloidal silica is 1 to 50 parts by weight with respect to 100 parts by weight of Al monophosphate.
If the amount is less than 1 part by weight, there is no effect of improving the densification and heat resistance of the film as in the case of boric acid. Absent. By these additives, the film properties such as the appearance, adhesion, heat resistance, insulation and corrosion resistance of the film are improved, and in particular, the effect of preventing seizure in strain relief annealing is large.

[Treatment method] The treatment solution is applied and baked by diluting the treatment solution to an appropriate concentration with water, applying a predetermined amount by a roll coater, and performing a short-time baking treatment at a baking temperature of 200 to 700 ° C.

[Amount of Coating] Next, the amount of the insulating film formed on the surface of the magnetic steel sheet is not particularly limited.
A range of 3 g / m ² is appropriate. That is, 0.5 g /
If it is less than m ² , sufficient punching properties cannot be obtained, and good results in terms of insulation properties, lubricity and the like are difficult to obtain. on the other hand,
If it exceeds 3.0 g / m ² , there is a risk of peeling of the insulating film during the strain relief annealing, and the space factor is poor, which is not desirable.

As described above, the resin emulsion used in the present invention has a particle size of 0.5 to 3.0 μm, and the addition amount thereof is 1 to 3 parts by weight per 100 parts by weight of aluminum phosphate.
It is limited to 00 parts by weight. Under these conditions, an electrical insulating film having a high space factor and excellent in weldability, punching properties, adhesion, heat resistance, and slipperiness after strain removal can be obtained.

[0015]

According to the present invention, by using Al primary phosphoric acid, boric acid, and colloidal silica as the inorganic components, a dense,
An insulating film with good adhesion and good heat resistance is formed. Further, in the present invention, the emulsion resin has a particle diameter of 0.5 to 3.
By using 0 μm resin, many very fine spherical projections are formed on the surface of the coating. It has been confirmed that many of these fine projections exist after the strain relief annealing.
According to the present invention, as a mechanism for improving the weldability, insulating properties after annealing, slipperiness, adhesion, corrosion resistance, etc., as described above, primary phosphoric acid Al, boric acid, good film properties due to inorganic components of colloidal silica, It can be inferred that the shape effect of the fine spherical projections created by the coarse particle emulsion matches and the improvement effect is obtained.

[0016]

[Embodiment 1] Next, an embodiment of the present invention will be described. As shown in Table 1, a non-oriented electrical steel sheet coil having a thickness of 0.5 mm after finish annealing, treated by a known method,
Then, a treating agent containing a component obtained by adding an emulsion resin having a particle diameter of 0.5 μm as a main component was applied by a coating apparatus of a rubber roll type, and baked at a plate temperature of 300 ° C. The coating amount at this time was 1.5 g / m @ 2 in weight after baking. A sample was cut out from this coil and a sample that had been subjected to a strain relief annealing at 750 ° C. × 2 Hr, and the film characteristics were investigated. Tables 2 and 3 show the results of a comparative example (Mg chromate + boric acid as an inorganic component) treated in the same manner as in the above examples.
Shown in As is clear from Tables 2 and 3, according to the present invention,
An electrical insulating film having a high space factor and excellent punching properties, adhesion properties and slip properties was obtained.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

Example 2 In the same manner as in Example 1, a 0.5 mm steel sheet after finish annealing
And a mixed solution of emulsion resins with different particle systems was applied and baked at a plate temperature of 250 ° C. The coating amount at this time was 1.2 g / m ² in terms of the weight after baking.
A sample was cut out from this coil and a sample that had been subjected to a strain relief annealing at 750 ° C. × 2 Hr, and the coating characteristics were investigated. Tables 5 and 6 show the results of Comparative Examples (Mg chromate + boric acid as inorganic components) treated in the same manner as in the examples.
As in Example 1, in the present invention, an electrical insulating film having a high space factor, excellent punchability, weldability, adhesion, and slipperiness as compared with Comparative Examples was obtained.

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6]

[Method of Measuring Slip Property] A commercially available surface property measuring instrument was used for measuring the slip property. Measurement condition is vertical load 100
g and a moving speed of 20 mm / s using a φ10 mm hard ball
ec. went in air. The sample was evaluated as acceptable if the coating did not peel off or had no flaws on the surface after repeated reciprocal rubbing 10 times, and the sample was rejected if the hard ball ball was caught or the flaws occurred on the coating surface.

[0025]

According to the present invention, a coating agent containing no chromium compound provides an electric power having a high space factor, excellent punchability, weldability, adhesion, slipperiness, etc. in the film properties before and after annealing. An electromagnetic steel sheet having an insulating coating is obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-169567 (JP, A) JP-A-3-240970 (JP, A) JP-A-61-183479 (JP, A) JP-A-54-1979 143737 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 22/00 C21D 9/46 501 H01F 1/16

Claims (3)

(57) [Claims] 1. A method according to claim 1, wherein the surface of the magnetic steel sheet is 100 parts by weight of a first phosphate solution of Al in terms of solid content, and has a particle diameter of 0.5 to 3.
A method for producing a non-oriented electrical steel sheet having extremely good coating properties, comprising uniformly applying a treatment liquid containing 1 to 300 parts by weight of an organic resin emulsion of 0 μm as a main component, followed by baking. 2. A method according to claim 1, wherein 100 parts by weight of a first phosphate solution of Al, 1 to 20 parts by weight of boric acid, 1 to 50 parts by weight of colloidal silica, or both, and A non-oriented electrical steel sheet having extremely good coating properties, characterized in that a treatment liquid containing 1 to 300 parts by weight of an organic resin emulsion having a diameter of 0.5 to 3.0 μm is uniformly applied and then baked. Production method. 3. The organic resin emulsion comprises one or more of acrylic, polystyrene, vinyl acetate, silicone, polyethylene, polypropylene, polyamide, polycarbonate, melamine, phenol, polyurethane, alkyd, isocyanate, and epoxy resin. 3. The method according to claim 1, wherein the non-oriented electrical steel sheet has an extremely good coating property.