JPS61297145A - Method of forming organic insulating film consisting of water-soluble resin of electromagnetic steel plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention relates to a method for producing an insulating coating on an electrical steel sheet, and in particular to a method for producing an organic insulating coating made of a water-soluble resin on an electrical steel sheet with excellent adhesion. be.

``Prior Art'' Generally, electromagnetic steel sheets used for the iron cores of motors and transformers for home appliances are continuously punched, laminated, and welded at the edges. In this punching process, if the adhesion of the insulating film is poor, problems such as peeling of the insulating film, seizing of the powder, shortening of the life of the die, and hindrance to work due to powder generation occur.

The insulation coating is applied after continuous annealing.

As shown in FIG. 3, the annealing furnace 1. The electromagnetic steel sheet 2 which has been annealed after passing through the cooling zone 3 is sent to the coated steel sheet cooling device 4 where it is brought to a predetermined temperature and then coated with insulation paint using a coating roll.

The coating device includes a coating roll 8. It consists of a metering opening/luer, a pickup roll 6, and a paint saucer 5.

The manufacturing process for electrical steel sheets that produced the above-mentioned insulating coating generally requires a long time from continuous annealing to application. etc., contact with the seed roll may cause foreign matter to adhere or become dirty, resulting in poor adhesion.

Furthermore, the insulation coating on electrical steel sheets is a very thin coating in order to lower the space factor.

To apply a thin and uniform insulation coating to the surface of a steel plate.

It is necessary to keep the viscosity of the paint as low as possible so that it spreads well on the surface of the steel plate.

However, if it takes a long time to apply, the temperature of the steel plate will drop to room temperature, and some paints may lack leveling properties even when applied to the surface of the steel plate, resulting in uneven coating, and in areas where the film is thick.
It has the disadvantage of poor adhesion.

The usual method of reducing the viscosity of paint to ensure leveling properties is to dilute it with an organic solvent, but this method is rarely used for coating insulation coatings on electrical steel sheets due to fire hazards and pollution concerns. Not put into practice.

The method currently employed is to dilute a water-soluble paint with water, apply it to a steel plate, and bake it to form an insulating coating.

Furthermore, as shown in JP-A No. 56-031477, a method has been proposed in which a water-insoluble coating resin and a coating roll are heated to 150 to 350°C. Replacement and maintenance of coating roll.

There are problems with workability such as changing paint.

``Problems to be Solved by the Invention'' However, the method of applying the water-soluble paint diluted with water as described in Tokage is also described as a comparative example in the aforementioned Japanese Patent Application Laid-Open No. 56-031477. However, after application, it is necessary to hold the coating in a hot air oven for a predetermined period of time, which has the disadvantage that a large amount of energy is required to remove water and harden the film.

This was developed in view of the following circumstances: ``Means for solving problems'' and ``Action 1: The present invention is described'', and its gist is that an organic coating made of a water-soluble resin is applied by electromagnetic coating via a coating roll. In a method for forming an insulating coating on electrical steel sheets, which is applied to the surface of a steel sheet and heated and baked, the temperature of the steel sheet before application is set to 60 to 1
By controlling the temperature to 00° C., an insulating coating with excellent adhesion due to the residual heat burning effect can be obtained by reducing the thermal load caused by baking after coating.

In other words, the present inventor has found that applying it to a high-temperature plate and baking it to dry it promotes drying and has an effect on adhesion, although it is slightly removed from the boundary between the sticky coating and the steel plate from the coating surface. From the perspective of reducing the heating load after coating, we shortened the time until the continuous annealing line in the continuous annealing line for electrical steel sheets, and used the residual heat of the steel plate during the cooling process after continuous annealing as energy for paint baking. We explored the conditions under which this would be possible.

As a result, in the conventional manufacturing process, the steel plate temperature before coating was 40°C or less, but after continuous annealing.

It was found that by shortening the time until application, it was possible to easily maintain a steel plate temperature of 60°C or higher before coating, and when the steel plate temperature was 60°C or higher, the viscosity of the paint decreased before coating, improving leveling performance. However, it was also found that uneven coating was eliminated and the coating could be applied uniformly to the surface of the steel plate.

At this time, the commonly used inexpensive coating roll 8 is 1
If the temperature exceeds 00°C, the service life will be shortened over time, so the upper limit of the temperature of the steel sheet before coating was set at 100°C.

Therefore, if the steel plate temperature exceeds 100°C, use the steel plate cooling device 4 before coating to reduce the temperature to the optimum temperature of 60 to 100°C.
control.

As mentioned above, the results of examining the correlation between the steel plate temperature before coating and adhesion, as well as the steel plate temperature before coating and the surface roughness of the coating, were first examined.
It is shown in the figure and FIG.

From Figure 1, when the steel plate temperature is 60℃ or higher, the adhesion is 10
It is clear that 0% passes the test, and it is also clear from Fig. 2 that a good result of Ra<0.4 μm is obtained when the steel plate temperature is 60°C or higher.

As a matter of course, the residual heat of the steel sheet acts on the coating and baking process, so that the heating load for baking after coating was reduced.

From the above, 1) the present invention has 2 no problems with workability;

Water-soluble organic coatings can be applied at relatively low plate temperatures and without heating the paint or application roll.

It was discovered that the adhesive has excellent adhesion.

"Example" An electrical steel sheet containing 3.2% Si was cold rolled to a thickness of Q, 5 mm.

This cold-rolled electrical steel sheet was heated at 900°C x 50°C in a continuous annealing furnace 1.
After annealing in an atmosphere of sec N2 (75) → -H2 (25), the temperature of the steel plate before coating was controlled at 60°C, and after baking a paint having the following composition (A) on the steel plate surface with a coating roll 8. The coating was applied so that the film thickness was 2.0 μm, and baking was performed after coating.

As a result, when the steel plate temperature before coating is 60°C, I(l
Even when bent by 180° at nφ, there was no peeling and the adhesion was excellent. When the coating thickness exceeded 5 μm, the peeling phenomenon became noticeable.

Composition [A]: Alxodo resin 45g: Melamine resin 55g Water 250g A comparative example is described below.

An electrical steel sheet containing 3.2% Si was cold rolled to a thickness of 0.5 m.

This cold-rolled electrical steel sheet was heated at 900°C x 50°C in a continuous annealing furnace 1.
After annealing in an atmosphere of sec N2 (75) → -H2 (25), the temperature of the steel plate before coating is controlled at 30°C, and the coating thickness of the coating after baking with the coating roll 8 is applied to the steel plate surface with the composition [A]. Apply so that the thickness is 2.0 μm.

After coating, baking was performed.

As a result, when the steel plate temperature before coating is 30℃, 10m■φ
When I bent it 180 degrees, a part came out that peeled off.

``Effect of the invention'' As described above, according to the present invention, the temperature of the steel plate before coating can be reduced to 6
By controlling the temperature between 0 and 100°C, the surface roughness of the coating after coating and baking is reduced compared to the conventional Ra≧0.4ttm.
Ra < 0.4 μm, and the leveling properties of the coating film are improved.
Second, the space factor was improved, adhesion defects were completely eliminated, and the heating load for baking after coating was reduced.

[Brief explanation of drawings]

Figures 1 and 2 serve as condition setting materials for the present invention and show the study results; a correlation graph between the steel plate temperature before coating and adhesion; a correlation graph between the steel plate temperature before coating and the surface roughness of the coating; and Figure 3: is an explanatory diagram of a continuous annealing line for electrical steel sheets. 1... Annealing furnace, 2... Electrical steel sheet, 3... Cooling zone. 4. Pre-coating steel plate cooling device, 5. Paint tray, 6.
... Pink up roll, 7... Metering roll, 8... Application roll. Sky's tormentor ω solicitation

Claims (1)

[Claims] In a method for producing an insulating film on an electrical steel sheet in which an organic film made of a water-soluble resin is applied to the surface of an electrical steel sheet via a coating roll and then heated and baked, the temperature of the steel sheet before application is set at 60 to 100°C.
A method for producing an organic insulating coating made of water-cooled resin on an electrical steel sheet, characterized in that an insulating coating with excellent adhesion is obtained by controlling the residual heat seizure effect.