JPH11152579A - Surface treating agent for nonoriented silicon steel and formation of coating using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the hygroscopicity in insulated coating of low temp. baked coating of an Al phosphate-emulsion resin series free from chromium and its bakability at the time of annealing. SOLUTION: This surface treating agent for a nonoriented silicon steel sheet excellent in coating characteristics is composed of 6 to 42 pts.wt. emulsion resin and 0.5 to 10 pts.wt. OH-contg. organic compd. as additives to 100 pts.wt. Al primary phosphate expressed in terms of a solid content. As the OH-contg. organic compd, one or >= two kinds selected from monohydric alcohols, polyhydric alochols and polyvinyl alcohols are added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for forming an insulating film not containing a chromium compound, and relates to a weldability, an adhesion, and the like.
The present invention relates to an insulating coating agent for non-oriented electrical steel sheets having excellent film properties such as slipperiness and, in particular, excellent corrosion resistance, punching properties, and seizure resistance during annealing, and a method for forming an insulating film 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, then subjected to strain relief annealing, stacked in a predetermined number, and welded, caulked or bonded. It is regarded as a stacked iron core. Normal,
The surface of the non-oriented electrical steel sheet is subjected to an electrical insulating film treatment. This insulation film has excellent corrosion resistance, punching properties, weldability, adhesion, high space factor, as well as insulation, seizure resistance during annealing, corrosion resistance after annealing, adhesion, and slipperiness. It is important to obtain good core properties and workability.

Heretofore, inorganic, organic, and inorganic-organic mixed films have been applied as insulating film agents according to the use conditions and purposes. The inorganic coating has excellent heat resistance and slipperiness after strain relief annealing, but is inferior in punchability. on the other hand,
In the case of an organic film, the punching property and adhesion are excellent, but the film is decomposed and destroyed by annealing, and the adhesion of the film after annealing is poor and cannot be used. An inorganic-organic mixed film agent has been developed to solve each of these disadvantages and is currently most commonly used. 50-1
Japanese Patent No. 5013 discloses an excellent space factor and adhesion by forming a film with a processing solution containing a dichromate and an organic resin emulsion such as vinyl acetate, butadiene-styrene copolymer, and an acrylic resin as main components. A film forming method has been proposed which can maintain good film performance even when performing strain relief annealing.

On the other hand, Japanese Patent Application Laid-Open No. 5-78855 proposes a film agent containing no chromium compound as a component system different from the above-mentioned invention. According to the above publication, phosphoric acid A
l, and an aqueous solution obtained by mixing a synthetic resin emulsion of PH1 to PH3 with a non-volatile content of both, and further adding a crosslinked resin powder having an average particle diameter of 5 to 15 μm to the aqueous solution. It is described that a coating composition is formed at a heating temperature of 250 to 500 ° C. as a coating condition. In this invention, the use of the resin emulsion of PH1 to 3 is described as the stability of the solution in an acidic mixed solution, and the purpose of adding coarse-grained powder resin is to form irregularities on the surface to improve air permeability during welding. It describes the effect of improving weldability.

Japanese Patent Application Laid-Open No. 6-330338 discloses that
As a similar chromium-free treating agent, a method of forming an insulating film mainly comprising 100 parts by weight of aluminum phosphate and 1 to 300 parts by weight of an emulsion resin having a particle diameter of 0.3 to 3.0 μm has been proposed. . According to the present invention, the heat-resistant coarse-grain emulsion resin and the spherical shape effect of the film surface maintain a high space factor, excellent weldability, punchability and adhesion, and provide excellent slipperiness and corrosion resistance after annealing. It is shown.

[0006]

In the treatment of the inorganic-organic mixed coating agent based on the Al-emulsion resin containing no chromium compound, which has been conventionally proposed, moisture absorption due to free PO ₄ in the coating is reduced. There is a problem that it is likely to occur and the corrosion resistance is inferior, the punching property is inferior, and the film fusing property at the time of annealing is inferior to the conventional chromium compound-containing film.

The present invention has been devised to improve the hygroscopicity (corrosiveness), punching property, and seizure resistance during annealing of a phosphoric acid Al-emulsion resin-based insulating film containing no chromium compound. is there. Accordingly, an object of the present invention is to provide an insulating film treating agent capable of obtaining corrosion resistance, punching property and annealing resistance equal to or higher than that of a conventional chromium compound-containing film treating agent, and a method of forming the film.

[0008]

The gist of the present invention is as follows. (1) 6 to 42 parts by weight of an emulsion resin in terms of solids and 0.5 to 1 of an organic compound containing OH as an additive, based on 100 parts by weight of aluminum phosphate as solids.
5% by weight surface treatment agent for non-oriented electrical steel sheet with excellent film properties. (2) As the OH-containing organic compound, one or more selected from a monohydric alcohol, a polyhydric alcohol, and a phenolic organic polymer are added. Excellent surface treatment agent for non-oriented electrical steel sheets. (3) As the OH-containing organic compound, one or two selected from butyl alcohol, cyclohexanol, furfuryl alcohol, phenol, benzyl alcohol, ethylene glycol, propylene glycol, hexylene glycol, glycerin, polyvinyl alcohol, and polyvinyl butyral The surface treatment agent for non-oriented electrical steel sheets according to (1) or (2), characterized by adding the above. (4) Acrylic, styrene,
(1) characterized by one or more selected from vinyl acetate, polyethylene, polypropylene, polyamide, polycarbonate, melamine, phenol, polyurethane, alkyd, isocyanate, and epoxy
(2) or (3) The surface treating agent for non-oriented electrical steel sheets having excellent film properties. (5) After uniformly applying the surface treating agent for non-oriented electrical steel sheets according to (1), (2), (3) or (4) to a continuously annealed steel sheet, baking at 170 to 300 ° C. A method for forming a film on a non-oriented electrical steel sheet having excellent film characteristics characterized by the following.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have argued that the disadvantages of the film properties of an Al-emulsion resin main component film are poor moisture absorption and punching properties after baking and poor seizure resistance during annealing. To solve the problem, we worked on improving the liquid composition and baking conditions.

As a result, by adding an organic compound containing an OH group at a fixed ratio to the composition of the aluminum phosphate-emulsion resin system, a conventional film not containing a chromium compound containing aluminum phosphate as a main component is obtained. Solved the drawbacks of the agent treatment, and succeeded in completing the present invention, which can significantly improve not only weldability, adhesion, and slipperiness, but also, in particular, corrosion resistance, annealing resistance, and punchability. The details will be described below.

In the application of the present invention, as a starting material, a non-oriented electrical steel sheet material that has been finally rolled is treated on a steel sheet surface that has been degreased and continuously annealed in a continuous line. The present invention is characterized by its treatment composition. That is,
Al phosphate is used as the phosphate, and a solution prepared by mixing 6 to 42 parts by weight of the emulsion resin with respect to 100 parts by weight is used as a base solution, and the organic compound containing OH is further contained in a range of 0.5 to 15 parts by weight. Is added.

The Al phosphate used in the present invention includes:
Al primary phosphate is used by the reaction of phosphoric acid with Al ₂ O ₃ or Al (OH) ₃ . Primary phosphoric acid A referred to in the present invention
l 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 has a composition of Al (H ₂ PO ₄ ) ₃ which is usually called primary phosphoric acid Al. An aqueous solution of the compound. 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 preparing the treatment solution, first, an aluminum phosphate is diluted with an appropriate amount of water, an emulsion resin is added, and an OH-containing organic compound is added. In particular, acrylic resin, styrene, vinyl acetate, polyethylene, polypropylene, polyamide, polycarbonate, melamine, phenol, polyurethane,
1 selected from alkyd, isocyanate and epoxy
It is desirable to use one or more species. Of course, these polymers and crosslinked products can also be used. These resins are stabilized as emulsion resins by a special particle growth reaction and an emulsification method. These emulsion resins can be industrially easily and inexpensively manufactured, and at the above-mentioned mixing ratio, a film having excellent appearance, denseness, excellent weldability and excellent slipperiness can be formed by low-temperature baking. .

The OH-containing organic compounds as important additives in the present invention include monohydric alcohols, polyhydric alcohols,
Phenolic organic polymer (copolymer may be 10)
0.5 to 15 parts by weight is added to 0 parts by weight of Al phosphate. In addition, as the OH-containing organic substance at this time,
It is desirable that one or more selected from butyl alcohol, cyclohexanol, furfuryl alcohol, phenol, benzyl alcohol, ethylene glycol, propylene glycol, hexylene glycol, glycerin, polyvinyl alcohol and polyvinyl butyral be added. When these are added, the liquid 1
In the case of polyhydric alcohols and polyhydric alcohols, direct phosphoric acid A
1 and the emulsion resin, and the mixture is stirred and adjusted. On the other hand, in the case of a phenolic organic polymer such as polyvinyl alcohol as a powder resin, for example, it is desirable to dissolve it in advance using warm water or hot water and gradually add it with stirring.

As more preferable conditions, polyhydric alcohols and phenolic organic polymers are more excellent in terms of stability during baking. In particular, when polyvinyl alcohol was added in a certain amount or more, good results were obtained in the film properties before and after annealing. The surface treatment agent of the present invention may optionally contain other additives such as a colloidal substance such as SiO ₂ , Al ₂ O ₃ and ZrO ₂ and a vitrification agent such as H ₃ PO ₃ and NaSiO _3. Can be included.

The treatment agent thus adjusted is applied and dried and baked by controlling the amount of application in an annealing line using a coating roll. The amount of application is determined according to the intended use of the product to be 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 excellent in film performance and appearance can be formed. Dry baking conditions include baking at a plate temperature of 170 to 300 ° C.

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, phosphoric acid A
1, the mixing ratio of the emulsion resin and the OH-containing organic compound of the additive is important. First, the ratio between the aluminum phosphate and the emulsion resin is important for determining basic properties such as weldability, punching properties, heat resistance, and adhesion. If the solid content is less than 6 parts by weight of the emulsion resin with respect to 100 parts by weight of the aluminum phosphate, the concentration of organic C in the surface layer of the film after baking is low, and the punching property is adversely affected. On the other hand, when the content exceeds 42 parts by weight, the resin concentration in the coating film is increased and the punching property is improved, but the welding property and the adhesion after annealing are reduced, so that it is limited.

The OH-containing organic compound, which is the most characteristic feature of the present invention, has a function of stabilizing free phosphoric acid and a function of increasing the concentration of organic carbon in the film surface layer after baking. OH
The compound is 0.5 to 15 parts by weight per 100 parts by weight of Al phosphate.
It is added in parts by weight. If the amount is less than 0.5 part by weight, the free reaction of fixing PO _{4 in} the film is weak, and the effect of improving the seizure during annealing is not sufficient. In addition, no effect of increasing the organic C concentration in the coating layer, particularly in the vicinity of the surface layer, is observed, and the effect of improving the punching property does not occur. On the other hand, when the amount is more than 15 parts by weight, discoloration occurs or a glossy and beautiful surface appearance cannot be obtained depending on the printing conditions. In extreme cases, stickiness due to the added organic substance itself may be generated, and the adhesion after annealing is deteriorated, which is limited. When the content is in the range of 0.5 to 15 parts by weight, good improvements in film performance such as appearance, moisture absorption resistance, punching properties, and annealing resistance can be obtained. However, considering the stability in weldability, heat resistance, adhesion after annealing, etc.,
The most preferred range is from 1.0 to 4.5 parts by weight.

The concentration of the treatment liquid adjusted as described above is adjusted with water, applied to the steel sheet surface after continuous annealing using a coating roll or the like, and dried and baked at a sheet temperature of 170 to 300 ° C. . In the present invention, by adding an OH-containing organic compound, free phosphoric acid and Al phosphate can be more stabilized. For this reason, compared with the case where it is not added, baking at a lower temperature is possible, and the energy consumption can be reduced. The plate temperature during drying is 170 ° C
If the amount is less than the above range, a sufficient hygroscopicity and the effect of preventing seizure during annealing cannot be obtained even with the additives of the present invention. On the other hand, 30
If the temperature exceeds 0 ° C., depending on the type of the resin component or the additive, uneven burning of the organic component may occur, resulting in poor appearance due to discoloration of the film. In addition, the concentration of the organic C film, particularly on the surface of the film, decreases, and the punching property decreases, which is not preferable.

[0020]

Next, the reasons for improving the film performance according to the present invention will be described. Although the reason why the present invention suppresses the hygroscopicity and prevents the seizure during annealing is not clear, an esterification reaction occurs due to the reaction between OH in the OH-containing organic substance and free PO ₄ of the aluminum phosphate. _It is considered that No. ₄ is stabilized and the effect of improving moisture absorption resistance and annealing resistance is obtained.
In order to improve the punching property, organic C in the coating layer, especially the surface layer
It is considered that by increasing the concentration and more uniformly filling the space between the emulsion resins with the organic substance, the lubrication effect at the time of punching can be improved, and the improvement effect can be obtained.

[0021]

EXAMPLES Example 1 A non-oriented electrical steel sheet coil having a thickness of 0.5 mm manufactured by a known method was finally annealed in a continuous line. Next, as shown in Table 1 in the same line, a treating agent obtained by adding an OH-containing organic compound to an aqueous solution of the main component of the phosphate-Al-emulsion resin was applied using a coating roll, and a sheet temperature of 2%.
A baking treatment was performed at 30 ° C. The coating amount at this time was 1 g / m ² in weight after baking.

Thereafter, a sample was cut out from the product coil, and the film characteristics were investigated.

[0023]

[Table 1]

[0024]

[Table 2]

However, the coating properties in the table were measured as follows. * 1) Touch resistance A: A sample was hung in the atmosphere of 50 ° C. and a humidity of 98%, and the surface condition after elapse of 7 days was evaluated. * 2) Punching performance: Number of punching times until the steel die, clearance 5%, and burrow height reach 50 μm. * 3) Weldability: current 120A, electrode Th-W (2.4mmφ), Ar flow 6l
/ min. Results of TIG welding with a tightening pressure of 50 kg / cm ² and a speed of 100 cm / min. * 4) annealing _{conditions: 750 ℃, 2Hr, N 2} 100%. * 5) Toughness B: Rust generation after standing at 30 ° C, 90 days, humidity 80%. * 6) Seizure: 30 × 40 mm steel plates 1 and 2 as shown in FIG.
As shown in FIG. 1 (a), the steel plates are laminated so that the longitudinal directions thereof are alternately perpendicular to each other, and tightened at a tightening pressure of 40 kg / cm ² as shown in FIG. 1 (b). After the annealing in ₂ , the seizure force of the steel sheet was measured by a spring balance 4 as shown in FIG. Reference numeral 3 in FIG. 1 is a dummy plate.

As a result of this test, when the treatment agent to which the OH compound of the present invention was added was applied, the surface appearance was glossy and better than when the treatment agent without the addition was applied. Regarding the characteristics of the coating film, in the examples before the annealing, no rust was generated on the surface in any of the examples of the present invention, and a better result was obtained in the punching test than in the case where no OH compound was added. Also, in the properties after annealing, in the examples of the present invention, no rust was generated, and the seizure during annealing was considerably improved as compared with the comparative material.

Example 2 A non-oriented electrical steel sheet coil having a 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 line as in Example 1, a treatment agent obtained by changing the amount of the OH-containing organic compound added to the aqueous solution of the main component of the Al-emulsion phosphate resin using a coating roll was used. It was applied and baked at a plate temperature of 250 ° C. The amount of coating at this time is 1.5
g / m ² .

Thereafter, a sample was cut out from the product coil, and the film characteristics were investigated. Table 4 shows the results.

[0029]

[Table 3]

[0030]

[Table 4]

As a result of the test, when the organic compound containing OH of the present invention was added, no rust occurred before and after annealing as in Example 1, and the seizure during annealing was significantly improved.
In addition, excellent punching results were obtained as compared with the case where the OH-containing organic compound was not added. These tendencies were more excellent when the amount of the OH-containing compound added was large within the range of the present invention. However, when the addition amount of the OH compound is too large as in Comparative Example 1 (20 parts by weight based on 100 parts by weight of Al phosphate in terms of solid content), rust is slightly observed and the weldability is poor. It became. Example 3 A 0.5 mm thick non-oriented electrical steel sheet coil manufactured by a known method was finally annealed in a continuous line. Next, the composition used in the present invention 3 of Example 2 was applied and baked at a plate temperature of 150 to 320 ° C. as shown in Table 5. The amount of coating at this time is 1.2 g / m2 in weight after baking.
Adjusted to ² .

Thereafter, a sample was cut out from the product coil, and the film characteristics were investigated. Table 6 shows the results.

[0033]

[Table 5]

[0034]

[Table 6]

As a result of this experiment, even when the treating agent of the present invention was used, when the baking temperature was too low, especially before annealing, rust was often generated due to moisture absorption. In addition, the weldability and the seizure resistance during annealing tended to be poor. On the other hand, when the baking temperature was too high at 350 ° C., the film surface appearance turned brown and the gloss was dull and poor. In the film properties, the corrosion resistance was slightly inferior, and the punching properties tended to decrease.

[0036]

According to the present invention, the addition of an OH-containing organic compound improves the moisture absorption resistance after baking, and the seizure resistance of the insulation film during strain relief annealing, in an aluminum phosphate-based emulsion resin-based insulating film. A strong improvement in sexuality is obtained. Furthermore, the present invention provides a technique for producing a non-oriented electrical steel sheet having excellent film properties, which can improve the punching property by improving the organic component distribution on the film surface.

Thus, the good problem is solved, and a non-oriented electrical steel sheet having a stable and good film performance can be obtained more comprehensively than when a conventional film agent containing no chromium compound is applied.

[Brief description of the drawings]

FIG. 1 Burn-in (fusion) of a film during strain relief annealing
It is a method of evaluating sex.

Continuing on the front page (72) Inventor Kenji Sachi 1 Fujimachi, Hirohata-ku, Himeji-shi, Hyogo Nippon Steel Corporation Hirohata Works (72) Inventor Yoshihiro Arita 1-1 Tobata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka New Nippon Steel Corporation Yawata Works (72) Inventor Osamu Tanaka 59 Nippon Steel Plant Design Co., Ltd.

Claims (5)

[Claims] 1. An emulsion resin of 6 to 42 in terms of solid content, based on 100 parts by weight of aluminum phosphate monobasic in terms of solid content.
0.1 parts by weight of an organic compound containing OH as an additive.
A surface treating agent for non-oriented electrical steel sheets, comprising 5 to 15 parts by weight. 2. The organic compound containing OH, wherein one or more selected from monohydric alcohols, polyhydric alcohols, and phenol organic polymers are added. Surface treatment agent for non-oriented electrical steel sheets. 3. Organic compounds containing OH include butyl alcohol, cyclohexanol, furfuryl alcohol, phenol, benzyl alcohol, ethylene glycol, propylene glycol, hexylene glycol,
The surface treating agent for non-oriented electrical steel sheets according to claim 2, wherein one or more kinds selected from glycerin, polyvinyl alcohol and polyvinyl butyral are added. 4. An emulsion resin comprising acryl, styrene, vinyl acetate, polyethylene, polypropylene, polyamide, polycarbonate, melamine, phenol,
The surface treating agent for a non-oriented electrical steel sheet according to claim 1, wherein the surface treating agent is one or more selected from polyurethane, alkyd, isocyanate, and epoxy. 5. The method according to claim 1, wherein the surface treatment agent for non-oriented electrical steel sheets is uniformly applied to a steel sheet that has been annealed continuously, and then baked at 170 to 300 ° C. A method for forming a film on a non-oriented electrical steel sheet.