JP3385192B2 - Surface treatment agent for non-oriented electrical steel sheet with excellent coating properties and coating formation method using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating film containing no chromium compound in a non-oriented electrical steel sheet and a method for forming the same, and has excellent film properties such as punchability, weldability, adhesion and slipperiness. In particular, the present invention relates to an insulating coating agent for non-oriented electrical steel sheets which is excellent in touch resistance and seizure resistance during annealing, and a method for forming an insulating coating using the same.

[0002]

2. Description of the Related Art As is well known, when a non-oriented electrical steel sheet is used for an iron core of a motor or a transformer, it is punched into a predetermined shape, strain relief annealing is performed, and a predetermined number of sheets are stacked and welded, caulked or bonded. It is used as a laminated iron core. Normal,
The surface of this non-oriented electrical steel sheet is subjected to an electric insulating film treatment. This insulating film has punching property, weldability, touch resistance, adhesion, high space factor in addition to insulation, seizure resistance during annealing, touch resistance after annealing, adhesion, Excellent slipperiness is important for obtaining good core characteristics and workability.

Conventionally, inorganic, organic, or inorganic-organic mixed coatings have been applied as the insulating coating agent depending on the use conditions and purpose. The inorganic coating has excellent heat resistance and slipperiness after strain relief annealing, but has poor punchability. on the other hand,
In the case of an organic coating, punching and adhesion are excellent, but the coating is decomposed and destroyed by annealing, and the adhesion of the coating after annealing is poor and it cannot be used. Inorganic-organic mixed coating agents have been developed to solve these drawbacks and are most commonly used at present. Japanese Patent Sho 50-1
No. 5013 discloses excellent space factor and adhesion by forming a film with a treatment liquid containing a dichromate and an organic resin emulsion such as vinyl acetate, butadiene-styrene copolymer, acrylic resin as a main component. A film forming method has been proposed in which good film performance can be maintained even if strain relief annealing is performed while maintaining the above. Further, Japanese Patent Application Laid-Open No. 5-78855 proposes a coating agent similar to that of the present invention, which does not contain a chromium compound. According to the above publication, an aqueous solution containing Al phosphate and a synthetic resin emulsion of PH1 to 3 are mixed in such a manner that the non-volatile content of both is defined, and further, a crosslinked body having an average particle diameter of 5 to 15 μm in the above aqueous solution. A coating composition in which a resin powder is added is proposed, and it is described that the treatment is performed at a heating temperature of 250 to 500 ° C. Further, in the above publication, the stability of the liquid in an acidic mixed liquid is described as the purpose of using the resin emulsions of PH1 to 3, and the formation of irregularities on the surface for the purpose of adding the coarse particle powder resin improves the air permeability during welding. The effect of improving the weldability is described.

Further, in JP-A-6-330338, phosphoric acid A is used as a similar chromium-free treatment agent.
A method of forming an insulating film has been proposed which has 100 parts by weight and 1 to 300 parts by weight of an emulsion resin having a particle diameter of 0.3 to 3.0 μm as main components. According to this publication, the heat-resistant coarse-grain emulsion resin and the spherical shape effect on the surface of the coating provide a high space factor, excellent weldability, punchability and adhesion, and excellent slipperiness and corrosion resistance after annealing. It is shown.

[0005]

In the treatment of the above-mentioned conventionally proposed inorganic-organic mixed coating agent of the phosphoric acid Al-emulsion resin system containing no chromium compound, the free PO ₄ in the coating film is used. There are problems that hygroscopicity is likely to occur, stickiness and corrosion resistance are deteriorated, and that the film fusion property during annealing is inferior to the conventional chromium compound-containing film.

[0006]

The present invention has been devised to improve the hygroscopicity and the seizure resistance during annealing of an aluminum phosphate-emulsion resin type insulating film containing no chromium compound. Accordingly, an object of the present invention is to provide an insulating film treating agent and a film forming treatment method thereof which can obtain corrosion resistance and annealing resistance equal to or higher than those of conventional chromium compound-containing film treating agents, and has the following features. (1) 0.5 to 100 parts by weight of monobasic aluminum phosphate in terms of solid content, 6 to 56 parts by weight of emulsion resin and 0.5 as an additive, an organic acid salt selected from Al, Mg, Ca, and Zn.
A surface treatment agent for non-oriented electrical steel sheet, containing 10 to 10 parts by weight and having excellent coating properties. (2) The organic acid salt selected from Al, Mg, Ca, Zn contains one or more kinds selected from formate, acetate, citrate, succinate, and tartrate. Surface treatment agent for non-oriented electrical steel sheets with excellent coating properties. (3) The emulsion resin contains one or two selected from acrylic, styrene, vinyl acetate, polyethylene, polypropylene, polyamide, polycarbonate, melamine, phenol, polyurethane, alkyd, isocyanate and epoxy (1) or (2) ) A surface treatment agent for non-oriented electrical steel sheet, which has excellent coating properties as described above. (4) Emulsion resin 6 was added to 100 parts by weight of aluminum monophosphate in terms of solid content on the surface of the continuously annealed steel sheet.
~ 56 parts by weight and an organic acid salt selected from Al, Mg, Ca, Zn as an additive in an amount of 0.5 to 10 parts by weight.
A method for forming a coating on a non-oriented electrical steel sheet having excellent coating characteristics, which comprises performing a baking treatment at 0 to 300 ° C. (5) A non-directional electromagnetic agent in which the organic acid salt selected from Al, Mg, Ca, Zn contains one or more kinds selected from formate, acetate, citrate, succinate, and tartrate. (4) A method for forming a coating film on a non-oriented electrical steel sheet, which is a surface treatment agent for steel sheet and has excellent coating properties. (6) For non-oriented electrical steel sheets in which the emulsion resin contains one or two selected from acrylic, styrene, vinyl acetate, polyethylene, polypropylene, polyamide, polycarbonate, melamine, phenol, polyurethane, alkyd, isocyanate and epoxy. A method for forming a coating on a non-oriented electrical steel sheet having excellent coating characteristics according to (4) or (5), which is a surface treatment agent.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have developed a liquid to solve the problems of hygroscopicity after seizure of the coating and seizure during strain relief annealing, which were the drawbacks of the coating properties of the Al phosphate emulsion main component coating. We worked on improving the composition and baking conditions. As a result, with respect to the main component composition of the primary phosphoric acid Al-emulsion resin system, Al, Mg, Ca, Zn
By adding one or more organic acid salt compounds selected from formates, acetates, citrates, succinates, and tartrates selected from Solves the drawbacks of the coating agent treatment that does not contain compounds, and can significantly improve not only weldability, punchability, adhesion, and slipperiness, but especially corrosion resistance and seizure resistance in strain relief annealing. We have succeeded in developing a surface treatment agent for non-oriented electrical steel sheets and a method for forming non-oriented electrical steel sheet coatings using the same. The present invention will be described in detail below.

In the application of the present invention, as a starting material, the final rolled non-oriented electrical steel sheet material is subjected to degreasing and continuous annealing in a continuous line to treat the surface of the steel sheet. The present invention is characterized by the composition of the treating agent.
That is, the phosphates of the main component is used is phosphate monobasic Al, the primary phosphate Al: 100 parts by weight of the emulsion resin: 6-56 parts by weight blended liquid based solution, further Al, The organic acid salt of Mg, Ca, Zn is 0.5 to
It is added in the range of 10 parts by weight.

Emulsion resins include acrylic, styrene, vinyl acetate, polyethylene, polypropylene,
One or more selected from polyamide, polycarbonate, melamine, phenol, polyurethane, alkyd, isocyanate and epoxy are used. Further, of course, these polymers and crosslinked products can be used. These resins are stabilized as emulsion resins by a special particle growth reaction and emulsification method. The mixed coating with the primary aluminum phosphate using these emulsion resins forms a coating excellent in appearance, denseness, weldability, adhesiveness, slipperiness, etc. within the above-mentioned blending range.

As the organic acid salt compound which is an important additive in the present invention, one or more kinds selected from formate, acetate, citrate, succinate and tartrate are primary phosphate A.
1 : 0.5 to 10 parts by weight is added to 100 parts by weight. When adding the organic acid salt, it is desirable to first prepare the organic acid salt substance as an aqueous solution with water or warm water in advance, and gradually add the main component solution while stirring. More preferable conditions are Al, M in terms of solution stability.
It is better to raise the ratio of the organic acid salt to some extent than to stoichiometrically balance the molar ratio of the metal element such as g, Ca, Zn and the organic acid. When the amount of the organic acid salt is increased to about 1.1 to 1.5, it tends to be more stable without being affected by the stability of the treatment agent and the coating work conditions.

The treatment agent thus prepared is applied and dried and baked by controlling the application amount in an annealing line using a coating roll. The coating amount is determined according to the intended use of the product to which it is applied. In the case of the agent of the present invention, if the weight after baking is 0.5 to 4.0 g / m ² , a film having excellent film performance and appearance can be formed. As a dry baking condition, a baking process is performed at a plate temperature of 170 to 300 ° C. to obtain a product.

Next, the reasons for limitation in the present invention will be described. In the liquid composition of the insulating film agent of the present invention, the mixing ratio of the primary phosphoric acid Al, the emulsion resin and the organic acid salt compound of the additive is important. First, the ratio of Al primary phosphate and emulsion resin is important for determining the basic performance such as weldability, punchability, heat resistance and adhesion. Primary phosphate by solids weight Al: relative to 100 parts by weight, an organic C of coating the surface layer after baking is less than emulsion resin 6 parts by weight
Low density adversely affects punchability, while 56
If it exceeds 5 parts by weight, the resin concentration in the coating increases and the punching property improves, but since the weldability and the adhesion after annealing decrease, it is limited to 6 to 56 parts by weight.

The most characteristic organic acid salt compound of the present invention has a stabilizing effect of free phosphoric acid and an effect of enhancing seizure resistance during annealing, and the latter improving effect is particularly remarkable. Organic acid salt primary phosphate Al: is added in an amount of 6-56 0.5-10 parts by weight to parts by weight: 100 parts by weight of the emulsion resin. If it is less than 0.5 part by weight, the fixing reaction of free PO _{4 in} the coating is weak and the effect of improving the seizure property during annealing is not sufficient. On the other hand, if it exceeds 10 parts by weight, the pH of the liquid is affected to cause precipitation of the additive or a glossy and beautiful surface appearance cannot be obtained. In an extreme case, the added organic acid salt itself may cause roughness of the coating surface. Further, since the adhesiveness after annealing is deteriorated, the addition amount of the organic acid compound is limited. When the amount of the above-mentioned organic acid compound added is in the range of 0.5 to 10 parts by weight, good film performance improvements such as appearance, moisture absorption resistance, punching resistance and annealing resistance can be obtained. However, considering stability in terms of weldability, heat resistance, adhesion after annealing, etc., the most preferable range is 1.0 to 8.0 parts by weight.

The treatment liquid thus prepared is adjusted in its concentration with water and applied to the steel sheet surface after continuous annealing using a coating roll or the like, and then the plate temperature is 170 to 30.
It is dried and baked at 0 ° C. The addition of organic acid salt in the present invention, more free phosphoric acid and the stabilization of the primary phosphate Al is obtained. Therefore, it is possible to perform baking at a lower temperature as compared with the case where no organic acid salt is added. However, if the temperature is lower than 170 ° C., sufficient hygroscopicity and seizure prevention effect during annealing cannot be obtained even with the additive of the present invention. On the other hand, if the temperature exceeds 300 ° C., the organic component may be unevenly burned depending on the type of the resin component or the additive, and the appearance may be deteriorated due to the discoloration of the coating, which is not preferable because the appearance, the adhesion, the punchability, etc. may be deteriorated. .

Next, the reasons for improving the coating performance according to the present invention will be described. Although it is not clear why the present invention suppresses hygroscopicity and seizure during annealing, Al, Mg, Ca, and Zn in the organic acid salt are free PO ₄ produced by Al primary phosphate. It is considered that it reacts to form a more stable phosphate compound and suppresses the hygroscopicity of the coating film after baking. Further, during annealing, Al, Mg, Ca, in the thermally decomposed organic acid salt, It is considered that Zn or the like binds to the phosphoric acid component in the coating film, stabilizes, and has the effect of suppressing the fusion action due to the phosphoric acid component.

In the present invention, the evaluation of the seizure (fusion) property of the film in the strain relief annealing was carried out by the method shown in FIG. 1a shows the laminated state of the samples, FIG. 1b shows the clamped state of the laminated samples, and FIG. 1c shows the measured state. As a specific evaluation method, samples cut out in a sample size of 30 mm × 40 mm are alternately laminated one by one such that the longitudinal direction of the sample is at a right angle as shown in a, and the bolt tightening pressure is as shown in b: Tighten at 40 kg / mm ² , and then stack and tighten this laminated body at 750 ° C x ₂ Hr, N ₂ 100%, DP1
After annealing under the annealing condition of 0 ° C., the seizure state is measured by measuring the peeling force with a spring balance as shown in c.

[0017]

EXAMPLES <Example 1> A non-oriented electrical steel sheet coil having a sheet thickness of 0.5 mm manufactured by a known method was finally annealed in a continuous line. Then, as shown in Table 1 on the same line, a treatment agent obtained by adding an organic acid salt to an aqueous solution of a primary phosphoric acid Al-emulsion resin main component is applied using a coating roll, and a plate temperature of 200 is applied.
A baking process was performed at ° C. The coating amount at this time was 1 g / m ² in terms of weight after baking.

After that, a sample was cut out from this product coil, and the film characteristics were investigated. The results are shown in Table 2.

[0019]

[Table 1]

[0020]

[Table 2]

As shown in Table 2, when the organic acid salt of the present invention was used as an additive and applied, the surface appearance was glossy and good. On the other hand, in Comparative Example 4 in which the organic acid salt was excessively added, the graininess which is considered to be caused by the precipitate was generated and the appearance was somewhat problematic. Regarding the coating properties, in the properties before annealing, in all of the present invention, good results were obtained without rusting as compared with the case where no organic acid salt was added. Also, in the characteristics after annealing, no rust was generated in the present invention, and the result was that the seizure property during annealing was significantly improved compared to the comparative material.
On the other hand, in the comparative example in which the organic acid salt was not added, the image sticking property was large and the film was defective. <Example 2> A non-oriented electrical steel sheet coil having a plate thickness of 0.5 mm manufactured by a known method was finally annealed in a continuous line. Then, as shown in Table 3 in the same as the line in Example 1, the
One processing agent and the organic acid salt is added by changing the added amount of the aqueous solution of phosphoric acid Al- emulsion resin main component was coated with a coating roll, sheet temperature shown in Table 3 150-3
A baking process was performed at 30 ° C. The coating amount at this time was 1.5 g / m ² in weight after baking. After this, a sample was cut from this product coil and investigated for coating properties. The results are shown in Table 4.

[0022]

[Table 3]

[0023]

[Table 4]

As shown in Table 4, even when the treating agent of the present invention is used, if the baking temperature is too low at 150 ° C.,
There is no problem in the appearance after baking, but it has a high hygroscopicity and many rusts were seen. Further, the weldability was slightly inferior, and the seizure resistance during annealing tended to be extremely inferior. On the other hand, when the baking temperature was too high at 330 ° C., the surface appearance of the coating was discolored to dark brown and the gloss was dull, which was unsatisfactory. In addition, the coating properties were slightly inferior in corrosion resistance and the punchability tended to be considerably lowered.

However, in the baking temperature range of the present invention, 210
All of those baked at ~ 290 ° C exhibited good appearance and coating performance, and particularly good results were obtained at 210 ~ 250 ° C.

[0026]

EFFECTS OF THE INVENTION According to the present invention, in the primary phosphoric acid Al-emulsion resin type insulating film, the addition of an organic acid salt improves the moisture absorption resistance after baking, and the resistance of the insulating film during strain relief annealing is improved. A significant improvement in seizure is obtained. Further, by optimizing the baking conditions, the concentration of organic components on the coating surface can be increased, and it becomes possible to manufacture a non-oriented electrical steel sheet having excellent coating characteristics such as punchability.

[Brief description of drawings]

FIG. 1 Image sticking (fusion) in strain relief annealing
It is a figure which shows the evaluation method of sex.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-41913 (JP, A) JP-A-7-180064 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 22/00-22/86 C21D 9/46 501 H01F 1/18

Claims (6)

(57) [Claims] 1. An emulsion comprising 6 to 56 parts by weight of an emulsion resin and 0.5 to 0.5 parts by weight of an organic acid salt selected from Al, Mg, Ca, and Zn as an additive with respect to 100 parts by weight of monobasic aluminum phosphate in terms of solid content. A surface treatment agent for non-oriented electrical steel sheet having excellent coating properties, characterized by containing 10 parts by weight. 2. The organic acid salt selected from Al, Mg, Ca and Zn contains one or more kinds selected from formate, acetate, citrate, succinate and tartrate. The surface treatment agent for non-oriented electrical steel sheet according to claim 1, which is excellent in coating properties. 3. The emulsion resin is acrylic, styrene, vinyl acetate, polyethylene, polypropylene, polyamide, polycarbonate, melamine, phenol,
The surface treating agent for non-oriented electrical steel sheets having excellent coating properties according to claim 1 or 2, which contains one or two selected from polyurethane, alkyd, isocyanate and epoxy. 4. On the surface of a steel sheet that has been continuously annealed, 6 to 56 parts by weight of emulsion resin and Al, Mg, C as additives with respect to 100 parts by weight of primary aluminum phosphate in terms of solid content.
A surface treatment agent for non-oriented electrical steel sheet containing 0.5 to 10 parts by weight of an organic acid salt selected from a and Zn is uniformly applied, and then baked at 170 to 300 ° C. A method for forming a coating on a non-oriented electrical steel sheet having excellent coating properties. 5. The non-oriented material wherein the organic acid salt selected from Al, Mg, Ca and Zn contains one or more kinds selected from formate, acetate, citrate, succinate and tartrate. 5. A method for forming a coating film on a non-oriented electrical steel sheet having excellent coating properties according to claim 4, which is a surface treatment agent for a non-oriented electrical steel sheet. 6. The emulsion resin is acrylic, styrene, vinyl acetate, polyethylene, polypropylene, polyamide, polycarbonate, melamine, phenol,
6. A surface treatment agent for non-oriented electrical steel sheet, containing one or two selected from polyurethane, alkyd, isocyanate and epoxy.
A method for forming a coating on a non-oriented electrical steel sheet having excellent coating characteristics as described above.