KR20000009632A - Backward coating method of non-chrome organic & inorganic substance insulating coating solution - Google Patents

Abstract

PURPOSE: A backward coating method for coating a non-chrome organic and inorganic substance insulating coating solution on the surface of a strip is provided which gives good coating and surface appearance characteristics. CONSTITUTION: In the backward coating method for coating a non-chrome organic and inorganic substance insulating coating solution on the surface of a strip which leads in between upper and lower coating rollers(16,26) by using an insulating coating apparatus(100) comprising an upper pickup roll(13) for picking up an insulating coating solution stored in an upper solution storing pan(12), an upper thickness controlling roll(14), an upper coater roll(10) contained the upper coating roller(16), the lower pickup roll(13) for picking up the insulating coating solution stored in a lower solution storing pan(22), the lower thickness controlling roll(24), and a lower coater roll(20) contained the upper coating roller(26), the non-chrome organic and inorganic substance insulating coating solution are coated on the surface of the strip in a state as follows. The specific gravity of coating solution is 1.23-1.25, a viscosity is 13-14 cps, and a temperature is 24-34°C. The upper and lower coating rollers are set up within the extent of the main speed rate of upper and lower pickup rolls(13,23) of 64-70%. The deviation between a central distance of upper and lower coating rollers(16,26) maintains within the extent of 20-21.5 mm. The lead-in strip maintains a temperature of 28-40°C and a lead-in angle(theta) of 3.0-4.5%.

Description

Reverse coating method of chromium-free and organic-based insulating coating solution

The present invention relates to a method for coating a chromium-free organic-based insulating coating solution proposed in Korean Patent Application No. 97-49228. More specifically, the present invention belongs to a reverse coating method using a chromium-free organic-based insulating coating solution on the surface of the non-oriented electrical steel sheet using a reverse coating device.

In general, non-oriented electrical steel sheet is punched and laminated, and then laminated sections are fixed and assembled by welding or the like, and are used as iron cores for motors and transformers. This iron core has a large interlayer resistance to reduce the eddy current loss, for this purpose it is advantageous that the insulating coating solution is coated on the surface of the steel sheet.

Coating of the non-oriented electrical steel sheet uses a three roll-type coater 100 as shown in FIG. The insulating coating apparatus 100, as shown in Figure 1, the upper pick-up roll 13, the upper thickness control roll 14, the upper coating roll 16 to pick up the insulating coating solution 11 stored in the upper solution storage fan 12 A lower pick-up roll 23 for picking up the insulating coating solution 21 stored in the upper coat roll 10 and the lower solution storage pan 22 including a lower thickness adjusting roll 24, and a lower coating roll 26. The lower coater roll 20 including the coater stand (coater stand) (9) is configured to be configured. 2 shows a detailed configuration of the upper coater roll 10 and the lower coater roll 20 of the insulating coater device.

In the coating apparatus, between the upper and lower coating rolls (16) and (26) of the upper and lower coat rolls (10) and (20), an electrical steel sheet (hereinafter referred to as a 'strip') 15 has a constant angle with the support roll 6 ( θ), which is referred to as a drawing angle, and the distance between the centers of the coating rolls 16 and 26 is called a deviation 8 between coating rolls, that is, an eccentricity.

Insulation coating device of the strip using the three-roll coating device is roughly divided into a reverse coating device and a forward coating device according to the driving direction of the roll. That is, as shown in Figure 2, when the strip 15 and the coating roll 16 is in contact with the reverse direction (reverse coating) if the direction of rotation of the strip 15 and the rotation direction of the coating roll 16 is configured to be reversed A) device, and if so, a forward coating device (not shown).

Again, the reverse coating apparatus is divided into 1/2 reverse coating apparatus (FIG. 3) and 1/4 reverse coating apparatus (FIG. 4) according to the amount of solution coated on the strip. That is, as shown in Figures 3 and 4, the solution in the solution storage fan 12 is buried in the pickup roll 13 and the thickness control roll 14, and the solution at this time can be seen as 1 . Subsequently, while the solution of 1 passes through the pickup roll 13 and the thickness adjusting roll, the rotation direction of the pickup roll 13 and the rotation direction of the thickness adjusting roll 14 are different from each other. 2 solutions are delivered. Up to this point the 1/2 and 1/4 reverse coating devices are identical. As shown in Figure 3, if the rotational direction of the thickness adjustment roll 14 and the rotational direction of the coating roll 16 is the same as the 1/2 solution buried in the coating roll 16 is all delivered to the coating roll 16 1 A solution of / 2 is delivered. The device thus constructed is called a 1/2 reverse coating device. On the other hand, as shown in Figure 4, when the rotational direction of the thickness control roll 14 and the rotational direction of the coating roll 16 is in the opposite direction, the 1/2 solution delivered to the coating roll 16 is delivered as a 1/4 solution, The device thus constructed is referred to as a quarter reverse coating device.

The 1/2 and 1/4 reverse coating apparatuses have been widely used for coating organic-inorganic composite coating solutions on non-oriented electrical steel sheets. Table 1 below shows an example of such an organic-inorganic complex coating solution.

Organic and inorganic complex coating solution Chemical composition (% by weight) Physical and chemical properties Remarks Calcium Chromate Cloydal Silica Resin (K382: brand name) Reducing agent (EG) importance Viscosity (cps) pH 42.0 23.2 30.0 4.8 1.21-1.22 5 ~ 8 5 ~ 7 C-6 solution

The chromate organic-inorganic complex coating solution, the problem of bubbles, storage and workability, etc. continue to be raised.

Foam is a bubble phenomenon that appears from the surface of the solution reservoir when the coating solution is continuously coated and circulated on the surface of the non-oriented electrical steel sheet. If this phenomenon continues to occur, the amount of bubbles generated increases as the coating process proceeds. There is a problem. Therefore, it is difficult to carry out continuous coating work stably for a long time because a separate work is required to artificially remove these bubbles.

In addition, shelf life refers to the stability over time that can be used again to stop the use of the solution for a certain period of time, the organic-inorganic complex coating solution is mainly used as a reducing agent of the chromic acid polyhydric alcohols, they change over time in the chromate solution There is a problem of poor storage. In particular, when the temperature becomes high or the pH value becomes low, this tendency becomes remarkable.

In addition, adverse effects on the human body due to the use of chromium, residual hexavalent chromium in the film promotes abnormal wear of the mold during punching process has a problem of shortening the life. In other words, when a reducing agent is used in the chromate solution, it is difficult to preserve the solution for a long time, and the coating becomes uneven and adhesion is inferior even when coated as it has changed over time.

Therefore, recently, a chromium-free (Cr-Free type) organic-inorganic insulating coating solution has been proposed in Korean Patent Application No. 97-49228, which improves workability such as air bubbles, storage properties, and the like.

By the way, the chromium-free organic-based insulating coating solution is excellent in foaming problems, storage properties, workability, but it was determined that the application is difficult to use the known coating method. In other words, the use solution is different from the conventional solution when applied to the strip, and in particular, because the viscosity is large and sticks when the solution is applied from the roll to the strip, it is not possible to obtain a film of the appropriate thickness and the surface is not beautiful. There was a characteristic that was not. That is, when the newly developed solution is coated by the existing method, there is a problem in that the film properties (insulation, adhesion, corrosion resistance) worsen, and in particular, the surface appearance is poor.

In general, a method of coating a coating solution on a steel sheet is not simply obtained by repeatedly carrying out coating conditions with a newly developed solution, but it is necessary to grasp the overall characteristics of the solution and to organically set coating conditions suitable for the solution characteristics. Therefore, high level of technical skills are required.

Accordingly, the present invention is to provide a coating method that can ensure excellent coating properties and surface appearance properties in consideration of the inherent surface tension of the newly developed chromium-free organic-based insulating coating solution and the viscosity characteristics when applied. .

1 is an overall configuration diagram of a general three roll type coating apparatus

Figure 2 is a detailed view of the upper and lower coating roll of Figure 1

3 to 4 is a configuration diagram of the coating roll for explaining the reverse coating method

Explanation of symbols on the main parts of the drawings

6 ... support roll 8 ......... deviation between coating rolls

9 ...... Coater stand 10, 20 ...

11, 21 .. Insulating coating solution 12, 22 ... Solution storage pan

13, 23 ... pickup roll 14, 24 ... thickness control roll

15 ... strip 16, 26 ... coating roll

The present invention for achieving the above object, the upper coater including an upper pick-up roll 13, the upper thickness control roll 14, the upper coating roll 16 to pick up the insulating coating solution stored in the upper solution storage fan 12 A lower coat roll 20 including a lower pick-up roll 23, a lower thickness adjusting roll 24, and a lower coating roll 26 to pick up the insulating coating solution stored in the roll 10 and the lower solution storage pan 22. In the reverse coating method for coating the surface of the strip introduced between the upper and lower coating rolls (16, 26) by using an insulating coating device 100 configured to include;

(a) The chromium-free organic-inorganic insulation coating solution,

A solution having a specific gravity of 1.23 to 1.25, a viscosity of 13 to 14 cps, and a temperature of 24 to 34 ° C .;

(b) the upper and lower coat rolls,

Peripheral speed ratio of the upper and lower pick-up rolls 13 and 23: 64 to 70% of the upper and lower thickness adjusting rolls 14 and 24

Circumferential speed ratio: 90 to 95%, and the circumferential speed ratio of the top and bottom coating rolls 16 and 26: 100 to 110%;

The deviation between the center distances of the upper and lower coating rolls 16 and 26 is maintained in the range of 20 to 21.5 mm;

(d) the temperature of the inlet strip 15 is in the range of 28 ~ 40 ℃,

It is configured to include coating a chromium-free organic-inorganic insulating coating solution on the surface of the strip in a state in which the inlet angle (θ) of the strip is maintained at 3.0 ~ 4.5 °.

Hereinafter, the present invention will be described in detail with reference to the drawings.

[Coating Solution]

The chromium-free organic-based insulating coating solution (hereinafter referred to as 'insulating coating solution') used in the coating method of the present invention is a solution disclosed in Korean Patent Application No. 97-49228. This solution is

(a) To 100 g of the phosphoric acid in a phosphate solution alone or in combination of monobasic magnesium salt or monobasic aluminum phosphate salt prepared by adding magnesium hydroxide or aluminum hydroxide to phosphoric acid.

(b) 13.9-70.2 g of the weight of the emulsion acrylic resin as a solid;

(c) 1.1-6.8 g of colloidal alumina by weight as solids,

(c) 0.25-1.95 g of the silane coupling agent in terms of solids,

(d) zinc nitrate is added to a content of 5.1-23.8 g,

It is composed by adjusting the concentration with water.

If the proposed solution is applied to the reverse coating as it is, it is difficult to set the reverse coating conditions that can obtain the film properties and surface appearance, in the present invention is characterized by using the specific gravity, viscosity of the solution used. This condition will be described later.

[Coating Device]

The insulation coating solution is applied to the 1/2 reverse coating device as shown in Figure 3 and the 1/4 reverse coating device as shown in FIG. As shown in FIGS. 3 and 4, the 1/2 or 1/4 reverse coating apparatus is accurate in the coating method because the advancing direction of the strip 15 and the rotation direction of the coating rolls 16 and 26 are opposite. The requirements are of paramount importance. In particular, when the viscosity is high when applied as a solution applied to the present invention, the setting of the peripheral speed ratio and the pulling angle of each roll is the most important setting factor. On the other hand, since the driving method of the reverse coating apparatus has been described above, it is omitted here.

[Coating Method]

Referring to the appropriate coating conditions of the insulating coating solution of the present invention using the reverse coating apparatus shown in Figures 3 and 4 as follows.

First, the specific gravity of the insulating coating solution according to the present invention is 1.23 ~ 1.25, the viscosity is 13 ~ 14cps, the temperature is preferably a solution in the range of 24 ~ 30 ℃.

When the specific gravity of the solution is less than 1.23 or the viscosity is less than 13 cps, the solution buried in the thickness control rolls (14, 24) during coating is thin so that a thin film is formed to lower the insulation and corrosion resistance, and in particular, the coating roll (16). There is a problem that tremors occur in the (26). In addition, when the specific gravity of the solution exceeds 1.25 or the viscosity exceeds 14 cps, it is not preferable because the coating thickness excessive phenomenon in which a wavy pattern is periodically generated from the center of the strip 15 to both ends due to the stiff insulating coating solution.

In addition, if the temperature of the insulating coating solution is maintained at less than 24 ℃ the adhesion is easily peeled off when banding, if the temperature of the solution exceeds 30 ℃ causes a problem that the viscosity of the solution is increased by rapid moisture evaporation.

The upper and lower coater rolls 10 and 20 have a circumferential speed ratio of the upper and lower pick-up rolls 13 and 23 to 64 to 70%, and a circumferential speed ratio of the upper and lower thickness control rolls 14 and 24 to 90 to 95. %, It is preferable to set the peripheral speed ratio of the top and bottom coating rolls 16 and 26 in the range of 100 to 110%, respectively.

If the circumferential speed ratio of the upper and lower pick-up rolls 13 and 23 is less than 64%, the amount of the solution to be picked up is insufficient, so that the amount of the solution transferred to the upper and lower thickness-adjusting rolls 14 and 24 is small, resulting in a thin film and insulating properties. , Corrosion resistance is poor. On the other hand, if the peripheral speed ratio of the upper and lower pickup rolls 13 and 23 exceeds 70%, there is a drawback that the coating thickness is thickly coated due to the excessively picked up coating solution.

In addition, when the circumferential speed ratio of the upper and lower thickness adjusting rolls 14 and 24 is less than 90%, the amount of the solution transferred to the coating rolls 16 and 26 is insufficient, and a thin film is formed, resulting in low insulation. On the other hand, if the circumferential speed ratio of the upper and lower thickness adjusting rolls 14 and 24 exceeds 95%, the chromic acid-free insulating coating solution delivered to the coating rolls 16 and 26 is excessive, so that a thick film is generated and uniform coating is not possible, thereby degrading weldability. Becomes a factor.

In addition, if the circumferential speed ratio of the upper and lower coating rolls 16 and 26 is less than 100%, shaking of the coater roll may occur or the coating surface may not be beautiful, while the circumferential speed ratio of the upper and lower coating rolls 16 and 26 is increased. If it exceeds 110%, the coater surface layer may be damaged or the coating roll coating layer may be torn.

On the other hand, as shown in Fig. 2, the deviation 8 between the center distances of the upper and lower coating rolls 16 and 26 is preferably maintained in the range of 20 to 21.5 mm. The reason is that if the deviation is less than 20 mm, the lower coating roll is Excessive pressing force applied to (26) causes tremor of the top and bottom coating rolls (16) and (26), which leads to a cotter roll trip (the roll shake pattern is formed in the transverse direction at the bottom of the strip (15). ). This is because if the deviation exceeds 21.5 mm, a "L" semicurvature phenomenon is caused in which the strip 15 is bent in the width direction after coating.

In addition, the temperature of the strip 15 is preferably in the range of 28 ~ 40 ℃. When the temperature of the strip 15 is less than 28 ° C., the reaction force with the insulating coating solution is remarkably lowered during cooling, and when the strip 15 enters the drying furnace 200, the surface of the strip 15 is fine due to a temperature deviation. The formation of water droplets may cause the coating layer to peel off. On the other hand, when the temperature of the strip exceeds 40 ℃, the viscosity of the coating solution is increased, which causes a rough surface of the coating solution, causing rapid moisture evaporation when the coating solution is coated on the strip, thereby peeling off the coating layer.

In addition, it is preferable to perform the coating operation while maintaining the inlet angle θ formed between the strip and the support roll 6 at 3.0 to 4.5 DEG. The reason is that when the inlet angle is less than 3.0 DEG, the tension is reduced. This is because the lower coating roll 26 is shaken excessively, and if it is larger than 4.5 °, the coating layer coated on the upper and lower portions of the strip 15 is not beautiful.

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

EXAMPLE

Insulation coating was performed on the non-oriented electrical steel strip having a thickness of about 0.5 mm by using a 1/2 reverse coating apparatus as shown in FIG. 3 and a 1/4 reverse coating apparatus as shown in FIG. 4. At this time, the insulating coating solution was used as the insulating coating solution of the present invention both the comparative example and the invention example, the solution conditions at this time was different as shown in Table 3. And, when coating with this solution, the operating conditions of the coating apparatus was as shown in Table 4 below.

division Conditions of Coating Solution importance Viscosity (cps) Solution temperature (℃) Inventive Example 1 1.23 13 28 Inventive Example 2 1.25 14 30 Comparative Example 1 1.10 ^* 10 ^* 20 ^* Comparative Example 2 1.30 ^* 16 ^* 35 ^* Comparative Example 3 1.36 ^* 20 ^* 50 ^* * Mark is outside the conditions of the present invention

Example Strip condition Deviation between coating rolls (mm) Main Speed Ratio (%) ^* Entrance angle (。) Temperature (℃) Top and bottom pick up roll Vertical thickness adjusting roll Top and bottom coating roll Inventive Example 1 3 28 20 64 90 100 Inventive Example 2 4.5 40 21.5 70 95 110 Comparative Example 3 2 ^* 20 ^* 10 ^* 64 90 60 ^* Comparative Example 4 5.5 ^* 35 22.5 ^* 80 ^* 100 ^* 120 ^* Comparative Example 5 6.5 ^* 40 24 ^* 90 ^* 110 ^* 150 ^* * The line speed (Line Speed) is 45MPM * The indication is outside the present conditions

When the insulation coating is performed under the coating conditions of Table 3 and Table 4, the shaking degree of the upper and lower rolls, the coating thickness of the coated steel sheet, and the adhesion of the coating are shown in Table 5 below. In addition, the coated specimens were taken to compare their characteristics, and the results are shown in Table 6 below.

Example Tremor of upper and lower rolls Adhesion (Peeling) Coating Thickness Inventive Example 1 Good 10 0.140 Inventive Example 2 Extremely good 10 0.145 Comparative Example 1 Bad 40 0.130 Comparative Example 2 usually 30 0.150 Comparative Example 3 Bad 50 0.170

division Before stress relief annealing Surface appearance Insulation (Amps) "L" curvature (mm) Surface roughness Corrosion resistance Weldability Inventive Example 1 Extremely good 0.10 8 0.19 Good Good Inventive Example 2 Extremely good 0.11 10 0.21 Good Good Comparative Example 1 Bad 0.95 12 0.18 Bad Good Comparative Example 2 usually 0.09 16 0.23 Good usually Comparative Example 3 Extremely poor 0.08 20 0.25 Good Bad

As shown in Table 4 and Table 5, in the case of the present invention Example (1-2), the surface appearance is extremely beautiful and the insulation after coating is good, the appearance (color, gloss) and heat resistance after stress relief annealing, insulation It was excellent and satisfied the requirements as a film.

On the contrary, in the case of the comparative example (1), since the deviation was lowered as compared to the invention example (1-2), the pressing force applied to the lower coating roll 26 was excessive, causing the coating rolls 16 and 26 to shake. This leads to a cotter roll trip. In addition, the tension (gravity) applied to the strip 15 at the inlet angle is excessive, causing the lower coating roll 26 to shake. In addition, if the circumferential speed ratio of the upper and lower coating rolls 16 and 26 is less than 100% of the line speed, vibration of the coating rolls 16 and 26 may occur or the coating surface may not be beautiful, resulting in roughness and poor corrosion resistance. Insulation is inferior.

On the other hand, when the circumferential speed ratio of the upper and lower thickness adjusting rolls 14 and 24 is less than 90%, the amount of the solution transferred to the coating rolls 16 and 26 is insufficient, and a thin film is formed, resulting in low corrosion resistance and insulation.

When the peripheral speed ratio of the upper and lower pick-up rolls 13 and 23 is less than 64%, the amount of the solution to be picked up is insufficient, so that the amount of the solution transferred to the upper and lower thickness adjusting rolls 14 and 24 is small, so that a thin film is generated, resulting in insulation and corrosion resistance. fell.

In the case of Comparative Example (2) and (3), the deviation was increased to 21.5 mm compared to the Inventive Example, resulting in "L" bending after coating. When the pulling angle is larger than 4.5 °, the coating layer coated on the upper and lower portions of the strip 15 may not be beautiful, and the surface may be rough, resulting in lower contact ratio.

On the other hand, when the peripheral speed ratio of the upper and lower coating rolls 16 and 26 exceeds 110%, the coater roll surface layer was damaged or the coater coating layer was thickly coated.

This can lead to poor weldability and a beautiful surface.

In addition, when the circumferential speed ratio of the upper and lower thickness adjusting rolls 14 and 24 exceeds 95%, the solution delivered to the coating rolls 16 and 26 is excessively coated, so that the weldability is poor and the surface appearance becomes rough and easily. This will result in the film peeling off.

When the peripheral speed ratio of the upper and lower pick-up rolls 13 and 23 exceeds 70%, the coating solution is thickly coated due to the excessive pick-up of the coating solution, resulting in poor weldability.

As described above, the present invention is able to coat the newly developed solution with a coating layer having excellent physical properties by completing the coating method that was impossible by the existing method by optimally adjusting the conditions of the chromium-free organic-based insulating coating solution and the coating operation conditions. It works.

Claims (1)

An upper coat roll (10) including an upper pick-up roll (13), an upper thickness control roll (14), and an upper coating roll (16) for picking up the insulating coating solution stored in the upper solution storage fan (12); A lower coat roll (20) including a lower pick-up roll (23), a lower thickness control roll (24), and a lower coating roll (26) for picking up the insulating coating solution stored in the pan (22). In the reverse coating method for coating the surface of the strip introduced between the upper and lower coating rolls (16, 26) by using the coating apparatus 100, a chromium-free organic base insulating coating solution, (a) The chromium-free organic-based insulating coating solution, A solution having a specific gravity of 1.23 to 1.25, a viscosity of 13 to 14 cps, and a temperature of 24 to 34 ° C .; (b) the upper and lower coat rolls, Peripheral speed ratio of the upper and lower pick-up rolls 13 and 23: 64 to 70% of the upper and lower thickness adjusting rolls 14 and 24 Circumferential speed ratio: 90 to 95%, circumferential speed ratio of the top and bottom coating rolls 16 and 26: set in the range of 100 to 110%, The deviation between the center distances of the upper and lower coating rolls 16 and 26 is maintained in the range of 20 to 21.5 mm; (d) the temperature of the inlet strip 15 is in the range of 28 ~ 40 ℃, Reverse coating method of the chromium-free organic-inorganic insulating coating solution comprising the step of coating the chromic acid free insulation coating solution on the surface of the strip in the state of maintaining the inlet angle (θ) of the strip at 3.0 ~ 4.5 °.