KR930003645B1 - Method for forming the insulating film of electrical steel sheets and strips - Google Patents

Abstract

The insulating film of an nonoriented electric steel plate is prepared by (a) mixing reactive oligomer and reactive monomer with the weight ratio of 7 to 4, (b) preparing insulating coating solution by adding 5-30 gm silica powder, 1-12 gm photopolymerization initiator and less than 0.5 gm organic pigment to the mixed solution of 100 gm, (c) UV irradiating to the coated steel plate, after coating uniformly the surface of the electric steel plate with the insulating solution.

Description

Electrical insulation film formation method of electrical steel sheet

The present invention relates to a method of forming an electrical insulating film on the surface of a non-oriented electrical steel sheet, and more particularly, to form an electrical insulating film by applying ultraviolet rays after coating an insulating coating solution for UV curing on the surface of the non-oriented electrical steel sheet It is about a method.

Non-oriented electrical steel sheets are used as iron cores for motors and transformers, and stress relief annealing is carried out for the purpose of stress relief annealing for the purpose of improving the magnetic properties after punching, and to reduce the heat treatment cost required for stress relief annealing. The two types are omitted and are used separately from demand.

The present invention is applied to the non-oriented electrical steel sheet to omit the stress relief annealing after punching the latter.

In general, electrical steel sheets are subjected to three types of insulating coatings of organic, inorganic, and mixed materials on their surfaces in order to suppress the generation of eddy currents and to reduce power loss.

As a technology for forming an insulating film of a conventional non-oriented electrical steel sheet, Korean Patent Nos. 25106 (Notification No. 87-2105) and No. 31208 (Notification No. 89), which have been filed and filed by the applicant in Korea. -3582) and 31.0319 (Gaz. No. 89-3583). These patents form an organic and inorganic mixed insulating film having both the advantages of an inorganic insulating film and the advantages of an organic insulating film. It is about a method.

However, the insulating film forming method proposed in the above patents has a disadvantage in that it takes a long time for drying and cooling because the film curing after coating is achieved by a heat curing method.

According to the present invention, an insulating coating can be formed in a short time by applying an ultraviolet curing treatment solution containing silica powder and an organic pigment to an electrical steel sheet and irradiating ultraviolet rays, and electrical insulation having excellent properties such as insulation, adhesion and appearance. The purpose is to form a coating on the surface of the non-oriented electrical steel sheet. Hereinafter, the present invention will be described.

The present invention relates to a method for forming an insulating coating of a non-oriented electrical steel sheet, to 5 to 30 grams of silica powder and photopolymerization initiator 1 with respect to 100 grams of a mixed solution containing a reactive oligomer and a reactive monoma in a weight ratio of 7: 4. Preparing an insulating coating solution by adding -12 grams and 0.5 grams of an organic pigment, and applying the insulating coating solution to the surface of the non-oriented electrical steel sheet in a conventional manner, and then irradiating ultraviolet rays. The present invention relates to a method for forming an electrically insulating film of an electrical steel sheet.

Hereinafter, each component and the reason for numerical limitation are demonstrated.

The reactive oligomers and reactive monomas are Acrylated Epoxy Oligomer and bifunctional Acrylic Monomer, which can react with ultraviolet rays, respectively. Since the coating property is deteriorated because the viscosity is too high as the reactive oligomer alone, reactive monomas are combined and added together for the purpose of the diluent in order to improve the applicability according to the viscosity downward. In the case of furnace 7: 4 or less, applicability | paintability is bad, and when it adds in more compounding ratio, since an applicability improvement effect is not so big, the weight compounding ratio of reactive oligomer and monoma is preferable.

The amount of the silica powder added to improve the insulation is preferably 5-30 grams per 100 grams of the mixed solution of the reactive oligomer and the reactive monoma, because the amount of the insulation is sufficient when the amount is 5 grams or less. This is because the effect cannot be obtained, and when the appearance exceeds 30 grams, the appearance appears poor.

The photopolymerization initiator is added 1-12 grams to 100 grams of the mixed solution containing a reactive oligomer and reactive monomer in a weight ratio of 7: 4, the addition time is less than 1 gram, the completion time of the coating film is delayed, more than 12 grams In addition, the fast-drying effect of these additions is almost modest, and since it is itself expensive and uneconomical, its proper addition amount is 1-12 grams.

In the case of the conventional chromium-organic resin insulating coating liquid, the surface color becomes light green as chromium is reduced from hexavalent to trivalent when forming a film, and the demand for the appearance of the product such as the surface color is increasing in demand. Although the composition of the insulating coating liquid of the present invention is different from the conventional chromium-organic resin insulating coating liquid, an additional organic pigment (Pigment) is added in order to exhibit an effect of maintaining the film color equivalent to that of conventional conventional materials. Without it becomes difficult. Therefore, it is preferable to add the organic pigment per 100 grams of reactive oligoma and monoma uniformly blended in a 7: 4 weight ratio as described above to 0.5 grams or less.

Even if a very small amount of the organic pigment is added, the desired color retention effect appears, and thus no additional lower limit is set. On the other hand, if the organic pigment is added at 0.5 grams or more, the organic pigments present in the film during UV irradiation will block UV penetration and cause uncured phenomena. Therefore, the maximum addition amount is limited to 0.5 grams. Cyanlne Green is most preferred. The coating method may be applied when applying the above-mentioned ultraviolet curing insulating coating liquid to the surface of the non-oriented electrical steel sheet, for example, it can be applied thinly and uniformly using a synthetic rubber roll.

In addition, the hardening method after application | coating is performed by the ultraviolet curing method instead of the normal thermosetting method. In this invention, a high pressure mercury lamp of 80 W / Cm is mentioned as a light source which irradiates an ultraviolet-ray.

Hereinafter, the present invention will be described in detail through examples.

EXAMPLE

To the surface of the non-oriented electrical steel sheet (0.4% Si, plate thickness: 0.5mm) of the insulating coating liquid composition as shown in Table 1 was applied thinly and uniformly with a synthetic rubber roll. The electrical coating coated with the insulating coating liquid was cured for 3 seconds in an ultraviolet curing furnace to form an electrical insulating film.

As described above, the coating properties of the tongue-thick electrical insulating film were measured, and the measurement results are shown in Table 2 below. (In addition, Comparative Example 4 was excluded from the characteristics test subject due to uncured phenomenon and poor appearance.)

TABLE 1

* HDDA (1.6Hexane Dial-Diacrylate)

** Photopolymerization initiator is a mixture of UV p36 and Irgacure 184 in a weight ratio of 5: 2.

TABLE 2

In Table 2, Insulation (Amps.) Is the storage current value when a current of 0.5V, 1.0A (amps) is input under 300PSI pressure, and adhesiveness (mm Φ) is the specimen after UV curing annealing. , 20, 30mm Φ in contact with the arc of 180 ° bent the minimum arc diameter without the film peeling, the appearance of the film is the appearance of the appearance of the result obtained by the conventional heat curing method as a visual contrast result.

As shown in Table 2, in the case of Inventive Examples 1, 2 and Comparative Example 1 to which silica powder was added, an insulation improvement effect can be obtained as compared to Comparative Examples 2 and 3, which are not added at all, and an organic pigment (Pigment) In Comparative Examples 1 and 3, which were not added at all, the surface color was transparent, whereas in Examples 1 and 2 to which the organic pigment was added, it had a good film appearance with light green color.

On the other hand, in Comparative Example 4 of Table 1 in which the silica powder and the pigment were added in excess, the appearance of the pigment was poor and the pigment was present in the coating to prevent the ultraviolet ray from penetrating into the coating. Curing phenomenon appeared.

That is, in the present invention, 1 and 2 have the characteristics that the film thickness, the insulating property, the adhesion, and the film appearance are at the same time good.

As described above, in the present invention, after coating the ultraviolet curable insulating coating liquid without adding any water, the insulating film is generated in a very short time by irradiating ultraviolet rays, and thus, unlike the conventional thermosetting method, post-processing work such as winding without separate cooling process is performed. It is made quickly and has the effect of advantageously progressing the consistent processing line.

Claims (1)

In the method of forming an insulating coating of a non-oriented electrical steel sheet, 5-30 grams of silica powder, 1-12 grams of a photopolymerization initiator, and organic based on 100 grams of a mixed solution containing a reactive oligomer and a reactive monoma in a weight ratio of 7: 4. Adding 0.5 grams or less of pigment to prepare an insulating coating solution; And uniformly applying the insulating coating liquid to the surface of the non-oriented electrical steel sheet in a conventional manner, and then irradiating an ultraviolet ray to the insulating coating solution.