JPH0238582A - Electrical steel sheet with formed insulating coating film - Google Patents

Abstract

PURPOSE:To produce an electrical steel sheet having superior electric insulating property, heat resistance, weldability, corrosion resistance and adhesion by incorporating a silane coupling agent into at least one of a silicate coating film and an upper coating film. CONSTITUTION:When an upper coating film contg. one or more kinds of compds. selected among chromic acid, phosphoric acid and salts of the acids is laminated on the surface of an electrical steel sheet with a silicate coating film in-between to form an insulating coating film, a silane coupling agent is incorporated into at least one of the silicate coating film and the upper coating film and one of the films is blended with org. resin. An electrical steel sheet having superior electric insulating property, heat resistance, weldability, corrosion resistance and adhesion can be produced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrical steel sheet coated with an insulating film and used as a core material for motors, transformers, etc. The present invention relates to an electrical steel sheet formed with an insulating film that not only has good weldability but also has excellent adhesion that can withstand slitting, punching, etc.

[Prior Art] Electrical steel sheets used as second cores in motors, transformers, etc. are coated with an insulating coating to reduce eddy current loss. This film is required to have excellent not only electrical insulation properties but also corrosion resistance, punchability, weldability, heat resistance, etc.

On the other hand, the conventional methods of forming an insulating film on electrical steel sheets are: (1) applying organic resin and baking after drying; (2)
(3) A method of applying an inorganic silicate such as lithium silicate and baking after drying; (4) A method of applying an inorganic material mainly composed of chromate and baking after drying; (4) A method of applying an inorganic material mainly composed of chromate and baking after drying; This method involves applying a mixture with an organic resin, drying it, and then baking it. However, the film obtained by the method (1) above has insufficient heat resistance and weldability, and the film obtained by the method (2) above has insufficient heat resistance and weldability.
The films obtained by methods () and (3) have poor punchability. Further, although the film obtained by the method (4) above has good heat resistance and weldability, which are the drawbacks of the above (1), the insulation properties are significantly lowered by strain relief annealing.

The inventors of the present invention have conducted various studies in hopes of eliminating the drawbacks of these insulating films and developing a film that satisfies all required properties such as electrical insulation, corrosion resistance, punchability, weldability, and heat resistance. As a result, a silicate film was formed on the surface of the electrical steel sheet, and one of chromic acid, phosphate, or their salts was applied on top of the silicate film.
We have developed a composite film in which an upper layer film containing at least one type of organic resin is formed, and a composite film in which an appropriate amount of organic resin is contained in these films (Japanese Unexamined Patent Publication No. 57781/1981).

[Problems to be Solved by the Invention] The composite film disclosed in the above publication has excellent insulation properties, punchability, heat resistance, weldability, etc. due to the combined effect of the silicate film and the chromate and/or phosphate film. This makes it extremely superior compared to conventional insulating films. However, this composite film has the drawback that parts of the film peel off during slitting or punching, and it has become clear that there is still room for improvement in this respect. That is, when processing an electromagnetic steel sheet into the final core material, a wide coil is slit to a predetermined width and then punched into a predetermined shape. Strong pressure using a stabilizer (pressing plate) to keep the winding coil in place, or a holding plate (felt, cork, etc.) to apply tension to the winding coil causes force and friction to act on it.
An insulating film with poor adhesion is easily peeled off due to friction, etc., and its performance as a core material deteriorates. In addition, peeled film debris may adhere and accumulate on stabilizers, felts, etc., and may even adhere to punching tools, causing various problems such as making cleaning work troublesome.

The present invention has been made with attention to such problems, and the object is to not only satisfy all required performances such as insulation, weldability, heat resistance, and punchability, but also to meet the requirements for adhesion. The object of the present invention is to provide an electromagnetic steel sheet on which an insulating film is formed that is good and does not peel off even when subjected to slitting, punching, etc.

[Means for solving the problems] The electrical steel sheet of the present invention that can solve the above problems has the following features:
An insulating film consisting of an upper film containing one or more of chromic acid, phosphoric acid, or their salts is formed on the surface via a silicate film, or an organic resin is blended into at least one of the above-mentioned films. In the electric T111 steel plate,
The gist is that one or both of the above films contain a silane coupling agent to enhance the physical properties of the film itself, particularly the abrasion resistance, and to improve the adhesion.
In the present invention, the silicate film formed on the surface of the electrical steel sheet not only serves as a base layer for the insulating film to improve adhesion but also has a rust-preventing function for the steel sheet.
Li2O for in2.

Na2O, one of 20 types or 2 flu or more is mo,
llz ratio [5i02/(20 to Li20”Na2O+)
] It is a composite in the range of 271 to 2o/1. The reason for this is that if the molar ratio is less than 271, the silicate film tends to absorb moisture and the steel plate tends to discolor or rust. This is because, despite the effectiveness of the coupling agent, the adhesion to the electrical steel sheet tends to decrease.

The constituent materials of the upper layer film formed on the silicate film include chromic acid or its salts such as MgCa, Zn, Na, etc., and phosphoric acid or its salts such as Al, Ca, Mg, Na, etc.
Preferred examples include salts such as , and the like.

In addition, the organic resin that may be blended into the silicate film and/or the upper layer film mainly has the effect of improving the punching processability of the film, and specifically, water-soluble type or emulsion type organic resins are used. acrylic resin,
Examples include vinyl acetate resin, polyurethane resin, epoxy resin, and phenol resin. These can be used alone or in combination of two or more types if necessary. Note that the effect of improving punching property by these resins can be effectively exhibited even if the resin is contained in only one of the silicate film or the insulating film, or if the resin is contained in an appropriate amount in both films, the punching property can be improved. becomes even better. The blending amount of the organic resin is not particularly limited, and is preferably in the range of 5 to 50% by weight based on the solid content in each film.

Next, the silane coupling agent that is blended into one or both of the silicate film and the upper layer film improves the physical properties of each film itself and the adhesion between the films and the electrical steel sheet, making it easier to use during slitting and punching. It is an indispensable ingredient in preventing peeling of the film. By the way, considering the original function of the silane coupling agent,
It is thought that the silane coupling agent effectively exhibits its characteristics only when it is blended into a mixed film of silicate and organic resin. However, as will be made clear in the examples below, the effect of the silane coupling agent is not limited to the above-mentioned mixed coating, and is not limited to coatings consisting only of silicate, or chromic acid and/or phosphoric acid. It was confirmed that even when added to the upper layer film consisting only of the system, its effect was effectively exhibited and the peeling resistance of the film could be significantly improved. However, the effect of adding a silane coupling agent is most effectively exhibited when it is blended into a composite film consisting of an inorganic substance such as a silicate and an organic resin, and especially when it is added to a composite film consisting of an inorganic substance such as a silicate and an organic resin. The best adhesion can be obtained by adding a silane coupling agent to both.

The amount of the silane coupling agent to be added may be determined appropriately while taking into consideration the balance between the adhesion improvement effect and the paintability.
The most common range is 3 to 25% by weight in terms of solid content, and if the content of the silane coupling agent is less than 3% by weight, the adhesion cannot be sufficiently improved, while if it exceeds 25% by weight. In this case, the paint solution tends to increase or gel, resulting in poor painting workability.

As the silane coupling agent that exhibits such an effect, all conventionally used silane coupling agents can be freely applied, so the present invention is not particularly limited, but the most typical ones are used. is the following general formula (wherein, X is an amine group, a vinyl group, an epoxy group, a mercapto group, a halogen, etc., and
(R3 represents the same or different hydrolyzable groups such as methoxy or ethoxy groups) Examples include compounds represented by silicate solutions, chromic acid and/or phosphoric acid solutions, or Particularly preferred are those that can be uniformly mixed or dispersed with a mixed solution of organic resin and organic resin.

The method for forming the film having the above structure is not particularly limited, and for example, a single solution or a mixed solution (usually an aqueous solution or emulsion) containing the film-forming material for forming the base layer is applied onto the electrical steel sheet. After 150~
Dry and bake at about 400°C, then apply a single solution or mixed solution (usually an aqueous solution or emulsion) containing the upper layer film constituent materials, dry and bake at about the same temperature as above.
Perform baking.

[Example] Electromagnetic steel plate (1% Si
) using a roll coater to apply the film forming agent shown in Table 1 on the surface of the
It was painted and then baked. However, the baking conditions for forming the base layer containing silicate were set at 270° C. for 60 seconds, and the baking conditions for forming the insulating film constituting the upper layer film were set at 330° C. for 90 seconds. The results are shown in Table 2.

However, the meaning of each symbol shown in Table 1 is as follows.

BM403J Silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd. [γ-GlycyF xibwavir trimethoxysilane] rsII603 (J: Silane coupling agent manufactured by l--Resilicon Co., Ltd. [γ-methacryloxypropyltrimethoxysilane] rLS412GI J: Organic resin [styrene/acrylic acid ester copolymer emulsion] manufactured by Hoechst Synthesis Co., Ltd. [Movinyl DM7B5 J: Organic resin [styrene/acrylic acid ester copolymer emulsion] manufactured by Hoechst Synthesis Co., Ltd.] r to M750 J Teikoku Kagaku Sangyo The water-soluble acrylic resin manufactured by Co., Ltd. and the film performance test and evaluation methods shown in Table 2 are as follows.

“Insulation J: Evaluated by interlayer resistance (Ω·cm2/sheet) measured in accordance with JI 5-C-2550.

``Adhesion J'' Each electric steel plate with a film formed thereon is slit through a slit line, and the state of film debris adhering to the holding plate (stabilizer) and holding cloth (felt) is observed.

(Judgment) ◎；○ △・×
m square), clearance...(10%), punching oil...
・Continuous punching test was conducted by setting the conditions of [Esso 7G3 (lubricating oil manufactured by Esso)] and punching speed (300 sheets/min), and the evaluation was based on the number of sheets punched until the burr height reached 50 μm. .

Now I can get the table. As a result, product defects such as the core 24 made of electrical steel sheets (local separation of the insulation film) can be eliminated, and the number of cleaning or replacement of stabilizers and punching tools can be reduced, improving workability and productivity. It is possible to increase

As is clear from Tables 1 and 2, the films of Examples 1 to 7 in which a silane coupling agent was added to one or both of the lower layer (silicate film) and the upper layer (insulating film) were stable. It has insulating properties and an extremely high level of adhesion, and in continuous punching tests, it was possible to punch out 900,000 or 1 million sheets without any problem.

On the other hand, the film of the comparative example in which the silane coupling agent was not blended in either the lower layer or the upper layer had very poor adhesion. Even when an organic resin is contained (Comparative Examples 2 and 3), the adhesion of the film cannot be improved to a satisfactory extent.

[Effect of the invention]

Claims (2)

[Claims] (1) An electrical steel sheet in which an insulating film consisting of an upper layer film containing one or more of chromic acid, phosphoric acid, or their salts is formed on the surface of the electrical steel sheet through a silicate film, the silicate film or the upper layer An electrical steel sheet on which an insulating film with excellent adhesion is formed, characterized in that at least one of the films contains a silane coupling agent. (2) An insulating film consisting of an upper layer film containing one or more of chromic acid, phosphoric acid, or their salts is formed on the surface of the electrical steel sheet via a silicate film, and at least one of the above films contains an organic resin. An electrical steel sheet formed with an insulating film with excellent adhesion, characterized in that at least one of the above-mentioned films contains a silane coupling agent.