JPH08257461A - Coating apparatus - Google Patents

Abstract

PURPOSE: To surely prevent pick-up defect and to obtain a uniform coating film at a high rate by arranging a coating material feed nozzle, capable of jetting a coating material uniformly in the width direction at a specific angle from the rotational direction to the exit roll peripheral surface side of the part of a pick-up roll dipped in the coating material, in a coating material pan. CONSTITUTION: The coating material 6 in the coating material pan 5 is picked up by the pick-up roll 1, transferred to an applicator roll 2 reversely rotating with a material 4 to be coated and continuously applied on the material 4 to be coated traveling while being wound on a back-up roll 3. At this time, the coating material 6 is jetted uniformly in the roll width direction at the angle of 90-180 deg. from the roll rotational direction to the exit roll peripheral surface side of the dipped part of the pick-up roll 1 from the coating material feed nozzle 10 through a coating material feed line 12. The dynamic pressure of the jetted coating material 6 prevents the intrusion of air entrainment layer and simultaneously forms a flow line opposite to the air entrainment due to the rotation of pick-up roll 1, thus the pick-up defect over the whole width of the pick-up roll 1 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll coater type coating apparatus capable of continuously and beautifully coating a strip-shaped material to be coated such as a cold rolled steel strip at a high speed.

[0002]

2. Description of the Related Art A roll coater type coating apparatus has been widely used for continuous coating of a strip-shaped material to be coated such as a cold rolled steel strip. As a roll coater type coating device, a system shown in FIG. 11 is generally used. This system is a reverse coating system in which the rotating direction of the applicator roll is opposite to the traveling direction of the material to be coated.
Pick up (lift) with the pickup roll 1,
After defining a predetermined film thickness with the applicator roll 2,
It is transferred to the material to be coated 4 that moves along the backup roll 3, and is widely used because the equipment is simple and the control is easy.

However, this roll coating method is
When trying to increase the line speed in order to improve productivity, it is necessary to increase the number of rotations of the pickup roll 1 and the applicator roll 2 at the same time. At that time, coating defects occur depending on the respective roll peripheral speeds. To do.
One of the coating defects is that the pick-up roll 1 rotates at a high speed, the ability of the pick-up roll 1 to lift the paint is reduced, and a bamboo leaf-shaped unpainted portion parallel to the traveling direction of the workpiece 4 is generated. There is a defective pickup.

As a measure for preventing a pickup defect that occurs when the pickup roll rotates at a high speed, the following method has been conventionally proposed. For example, as shown in FIG. 12, the guide member 7 for partitioning the interior of the paint pan 5 into the pickup roll 1 side and the applicator roll 2 side has a gap between the guide surface and the peripheral surface of the pickup roll 1 approaching the applicator roll 2. A device provided in the paint pan 5 so as to extend along the roll peripheral surface of the pickup roll 1 to the contact point between the roll and the applicator roll 2 (see Japanese Patent Laid-Open No. 63-143963). , As shown in FIG. 13, the gap between the pickup roll 1 and the applicator roll 2 immediately before contact with the paint 6
14 is a device (see Japanese Patent Laid-Open No. 2-174961) in which a raising nozzle 8 for raising the coating liquid surface of the paint pan 5 along the lengthwise direction of the gap so as to be filled with As shown in the drawing, an apparatus in which the paint stream line in the paint pan 5 is uniform over the entire circumference of the pickup roll 1 and a chamber 9 is provided at the end of the paint pan 5 to make the physical properties of the lifted paint uniform (Japanese Patent Laid-Open No. Sho 63). -23135
No. 1), etc. have been proposed.

[0005]

However, each of the above-mentioned devices has the following drawbacks. That is, the means for providing the guide member 7 in the paint pan 5 for partitioning the pickup roll 1 side and the applicator roll 2 side is difficult to adjust the gap in the roll width direction when the guide member 7 is installed, and the gap is accurately set. If this is not done, the amount of coating liquid supplied will become non-uniform in the roll width direction, and this will affect the accuracy of the final coating film thickness. Further, the means for providing the raising nozzle 8 for raising the coating liquid surface in the paint pan 5 violently blows the coating liquid from the nozzle in order to lift the coating liquid from the liquid surface of the coating pan, so that the liquid surface of the coating pan is disturbed. However, there is a problem that air bubbles are caught. Further, since the means for providing the chamber 9 at the end of the paint pan 5 is intended to make the paint streamline in the paint pan 5 and the physical properties of the paint uniform, it is hardly effective in preventing pickup defects. Absent.

The present invention has been made in order to solve the above-mentioned drawbacks of the prior art, and in a reverse coat type coating apparatus, it is possible to reliably prevent pick-up defects that occur when the pick-up roll rotates at a high speed, and to make the pick-up roll uniform at a high speed. An object of the present invention is to provide a coating device that can obtain a coating film.

[0007]

The present inventors have conducted various experiments and studies on the behavior of pick-up defects caused by high-speed rotation of a pick-up roll that occurs in a conventional roll coater type coating apparatus. For example, FIG. 4 shows the result of observing the occurrence of pickup failure from below the pickup roll using a visible paint pan. 4A and 4B are schematic diagrams of a pickup failure. FIG. 4A shows the start of air entrainment, FIG. 4B shows the growth of the air entrainment layer, and FIG. 4C shows the penetration of the air entrainment layer. That is, when the pickup roll peripheral speed is low, air entrainment is not observed, but when the pickup roll peripheral speed is increased, as shown in FIG.
As shown in (a), a triangular air entrainment layer begins to be observed from the entrance side, and as the pickup roll peripheral speed increases, the air entrainment layer expands as shown in (b).
Finally, as shown in (c), the air entrainment layer reached the roll exit side, and the amount of paint lifted up was insufficient. From this result, it was found that the defective pick-up was air entrainment due to high-speed rotation of the pick-up roll.

As shown in FIG. 4 (c), the pickup roll peripheral velocity (hereinafter referred to as "limit pickup roll peripheral velocity") when the air entrainment layer generated along with the pickup roll reaches the roll outlet side. Fig. 5 shows the results of the examination of the effect of the immersion depth of the pickup roll on). From this result, it is understood that the peripheral speed of the pick-up roll increases as the immersion depth of the pick-up roll increases. In other words, it was found that the deeper the immersion depth of the pickup roll, the less likely it is that a pickup defect will occur.

Further, considering the pressure balance when the air entrainment layer reaches the bottom of the pickup roll, as shown in FIG. 6, the static pressure due to immersion of the pickup roll = ρlgh The dynamic pressure due to the movement of the air entrainment layer. = 1 / 2ρgV ² where ρl: paint density (kg / m ³ ) ρg: atmosphere gas density (kg / m ³ ) h: pickup roll immersion depth (m) V: pickup roll peripheral velocity (m / s) Become.

Here, in the conventional roll coater, if the dynamic pressure due to the movement of the air entrainment layer is greater than the static pressure due to the immersion of the pickup roll, the air entrainment layer passes through the bottom of the pickup roll and reaches the exit side. Conceivable.

Based on these results, the present inventors obtain a pressure higher than the dynamic pressure generated by the movement of the air entrainment layer that accompanies the pickup roll from the dynamic pressure caused by the flow of the coating liquid, and thus the air entrainment layer. It has been found that it is possible to prevent the entry of.

That is, according to the present invention, as a means for obtaining a pressure equal to or higher than the dynamic pressure due to the movement of the air entrainment layer, a paint supply nozzle is arranged in the paint pan, and the dynamic pressure due to the coating liquid flow is obtained by this nozzle to obtain the air. The purpose of this is to prevent the entrainment layer from entering, and the gist thereof is 90 to 90 degrees with respect to the rotation direction of the roll on the side of the roll on the exit side of the paint immersion portion of the roll.
It is characterized in that a paint supply nozzle capable of spraying paint uniformly in the roll width direction at an angle of 180 degrees is arranged in the paint pan (first invention). Further, in the same roll coater type coating apparatus, the paint jetted from the paint supply nozzle forms a streamline that is uniform in the roll width direction and that is reverse to the rotation direction of the pickup roll (second aspect). invention). Further, in a roll coater type coating apparatus, a paint supply nozzle for ejecting the paint to the peripheral surface of the pickup roll so as to form a uniform streamline in the width direction of the pickup roll in the paint pan, and the paint is supplied to the nozzle. And a discharge port for the paint in the paint pan, which is provided on the side opposite to the supply nozzle (third invention).

[0013]

In the first aspect of the invention, the dynamic pressure of the paint ejected from the paint supply nozzle is used to supplement the pressure sufficient to withstand the dynamic pressure caused by the movement of the air entrainment layer. Since the sum of the dynamic pressure of the paint and the dynamic pressure due to the movement of the air entrainment layer is greater than or equal to the dynamic pressure of the air entrainment layer, the entry of the air entrainment layer is blocked. Therefore, the paint can be sprayed uniformly in the width direction of the pickup roll. A paint supply nozzle is provided.

With respect to the spray direction of the paint, if the same direction as the peripheral speed direction of the pickup roll is 0 degree and the completely opposite direction is 180 degrees, the dynamic pressure of the sprayed paint will be air. It is necessary that the angle is 90 ° (on the vertical center line of the pickup roll) to 180 ° (parallel to the coating surface) with respect to the direction in which the entrainment layer is prevented from entering, that is, the rotation direction of the pickup roll. Therefore,
According to the present invention, the paint supply nozzle is provided on the side of the exit side roll of the part immersed in the paint at 90 to 180 with respect to the rotating direction of the roll.
It was decided to set it within the range of degrees. That is, when the spray angle of the paint is less than 90, the paint is sprayed in the entering direction of the air entrainment layer, and the dynamic pressure that can prevent the entrance of the air entrainment layer cannot be obtained. This is because when the angle is equal to or more than the angle (opposite to the air blowing direction), the spraying direction of the paint gradually deviates from the roll peripheral surface of the pickup roll, so that the effect of preventing the air entrainment layer from entering cannot be obtained. Of course, the effect of preventing the entry of the air blowing layer is maximum when the spray direction of the paint is 180 degrees.

Next, in the second aspect of the present invention, by ejecting the paint from the paint ejection nozzle to form a uniform streamline in the roll width direction, pick-up defects can be prevented in the entire width of the pick-up roll. Since the amount of paint lifted is sufficient and uniform, a beautiful coating surface can be obtained at high speed.

According to the third aspect of the present invention, a certain amount of paint can be supplied from the paint supply system to the paint jet nozzle provided to form a uniform streamline in the width direction of the pick-up roll. The amount of lifting can be made uniform in the roll width direction to make the coating thickness uniform in the width direction, and excess paint can be discharged from the paint discharge port provided on the side opposite to the paint supply nozzle, so a constant immersion depth can be achieved. Therefore, the pickup roll can be kept flowing, and flow can be generated from the exit side (lifting side) of the pickup roll to the entrance side to prevent the air entrainment layer from entering.

[0017]

【Example】

Example 1 FIG. 1 is a schematic view showing an example of the apparatus configuration of the present invention, FIG. 2 is a schematic view illustrating an installation position of a paint supply nozzle in the same apparatus, and FIG. 3 is a view illustrating a paint supply nozzle in the same apparatus. (A) is a perspective view showing a porous nozzle, (b) is a perspective view showing a slit nozzle, 10 is a paint supply nozzle, 11 is a discharge port, 12 is a paint supply system, 12-1 is a supply pump, 12-2 is a paint tank.

As shown in FIG. 3 (a), the paint supply nozzle 10 has a nozzle body 10-1 having substantially the same length as the pickup roll 1 and a plurality of ejection holes 10-2 arranged at equal intervals in the longitudinal direction. 3B, or a slit-shaped nozzle in which a slit-shaped ejection hole 10-4 is provided in a nozzle body 10-3 having substantially the same length as the pickup roll 1 is used, as shown in FIG. 3B. . Both the porous nozzle and the slit nozzle have a structure capable of uniformly ejecting the coating in the width direction of the pickup roll. Therefore, the nozzle is not limited to the porous nozzle and the slit nozzle as long as the paint can be jetted uniformly in the width direction of the pickup roll.

In the coating apparatus shown in FIG. 1, a paint supply nozzle 10 is installed on a side surface of a paint pan 5 in a direction opposite to an air entrainment layer entrance direction, and a paint supplied from a paint supply system 12 is picked up by a pickup roll. 1 for the roll surface of the exit roll of 1
It is configured to eject at an angle of 80 degrees.

In the coating apparatus, the paint in the paint pan 5 is picked up by the pick-up roll 1 and the coated material 4
And transferred to the applicator roll 2 that rotates in reverse,
The material 4 to be coated is continuously applied while being wound around the backup roll 3. At this time, the paint 6 is jetted by the paint supply system 12 from the paint supply nozzle 10 in a direction opposite to the peripheral speed direction of the pickup roll 1, and thus the dynamic pressure of the jetted paint prevents the air entrainment layer from entering. At the same time, by spraying the paint uniformly into the paint pan 5 in the roll width direction, a streamline that opposes the air entrainment accompanying the rotation of the pickup roll 1 is formed, so that the pickup roll 1 is not picked up in its entire width. Is prevented, the amount of paint lifted is sufficient and uniform, and a beautiful coating surface is obtained. Excess paint in the paint pan 5 is discharged from the discharge port 11. In addition, the replenishment of paint reduced by continuous painting is
The paint is supplied from the paint supply system 12 including the supply pump 12-1 and the paint tank 12-2.
Supplied within.

Further, as shown in FIG. 2, one or a plurality of paint supply nozzles 10 may be arranged so as to be immersed in the paint in the paint pan 5. In that case, in order to effectively utilize the effect of dynamic pressure due to the flow of the paint, the nozzle installation direction should form an angle θ (90 to 180) with respect to the direction of the pickup roll peripheral speed.
Range). The number of the paint supply nozzles 10 installed is not particularly limited, and the paint supply nozzles 10 are provided within the range of the angle θ (90 to 180 degrees) according to the size of the paint pan or the pickup roll and the scale of the coating apparatus.

Example 2 The limit pick-up roll when the slit-shaped nozzle (width 2 m, slit interval 3 × 10 ⁻³ m) shown in FIG. 3 (b) was installed (jetting direction 180 °) in the coating apparatus shown in FIG. 1. The peripheral speed is shown in FIG. 7 in comparison with the conventional coating device shown in FIG. The operating condition in this embodiment is a line speed of 90 m.
/ Min, pick-up roll immersion depth 0.03 m, paint viscosity 0.15 Pa · S, surface tension 0.06 N / m, and the material to be coated (thickness 1.0 mm) immediately after being transferred by the applicator roll. The amount of indentation between the rolls was controlled so that the coating film thickness on the strip steel) was 30 μm.

From the results shown in FIG. 7, the limit speed of the pick-up roll was about 1 m / s in the conventional apparatus, but the limit speed of the pick-up roll was significantly increased in the apparatus of the present invention. Further, the peripheral speed of the limit pickup roll was further improved with the increase of the coating material supply amount. It is presumed that this is because the dynamic pressure increases due to the increase in the speed of the paint spray from the paint supply nozzle, and the air entrainment that accompanies the applicator roll is suppressed. As a result, in the device of the present invention, not only at a low line speed but also at a high line speed, a beautiful coated surface was obtained.

Example 3 FIG. 8 shows the results of examining the effect of the spray angle (nozzle angle) of the paint supply nozzle (slit nozzle) on the peripheral speed of the pick-up roll by using the same coating apparatus as in Example 2. In this embodiment, as shown in FIG. 9, the paint spray angles θ ₁ , θ ₂ , and θ ₃ are 180 degrees, 135 degrees, and
This is the case of 90 degrees. The operating conditions were the same as in Example 2.

In the conventional apparatus, as shown in the second embodiment, the limit pickup roll speed is 1 m / s, while
In the case of the device of the present invention, it can be seen that the peripheral speed of the limit pickup roll is improved at any injection angle.
Further, the limit pick-up roll peripheral velocity increases most when the injection angle θ ₁ is 180 degrees, and then decreases in the order of 135 degrees (θ ₂ ) and 90 degrees (θ ₃ ). It is speculated that by installing the paint supply nozzle every time, a sufficient flow was formed against the air entrainment layer that enters along with the pickup roll, so that the entry could be blocked efficiently. It

Example 4 The result of examination of the flow velocity distribution in the width direction in the paint pan near the pickup roll by the same coating apparatus as in Example 2 is shown in FIG. 10 in comparison with the conventional apparatus. The supply of the paint in the conventional apparatus is performed from a supply pipe provided at the end of the side wall of the paint pan (the end of the pickup roll).

As is clear from the results shown in FIG. 10, in the case of the conventional apparatus, the flow of the paint in the paint pan has a negative velocity at both ends of the pickup roll, that is, the paint is wound from the rear to the front of the roll, and the center of the roll is in the center. Since the part shows a positive velocity, it flows very unevenly, whereas in the case of the device of the present invention, a uniform flow is formed over the entire width of the pickup roll, and this uniform flow is picked up. It shows that defects can be prevented over the entire width of the pickup roll.

[0028]

As described above, according to the apparatus of the present invention, it is possible to almost completely prevent a pickup defect due to air entrainment that occurs when the pickup roll rotates at a high speed. Even if it is difficult to make a beautiful coating with the device, it has an excellent effect that a beautiful coating with high smoothness can be applied.

[Brief description of drawings]

FIG. 1 is a schematic view showing an apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic view illustrating an installation position of a paint supply nozzle in the same apparatus.

3A and 3B are views exemplifying a paint supply nozzle in the same apparatus, wherein FIG. 3A is a perspective view showing a porous nozzle, and FIG. 3B is a perspective view showing a slit nozzle.

FIG. 4 is a schematic diagram of a pickup failure in a roll coater type coating apparatus, in which (a) is at the start of air entrainment and (b) is
Represents the growth of the air entrainment layer, and (c) represents the penetration of the air entrainment layer.

FIG. 5 is a diagram showing a relationship between a limit pick-up roll peripheral speed and a pick-up roll dipping depth in a conventional roll coater type coating apparatus.

FIG. 6 is an explanatory diagram regarding pressure balance in a paint pan of a roll coater type coating device.

FIG. 7 is a diagram showing the relationship between the peripheral speed of the pick-up roll and the amount of paint supplied in Example 2 of the present invention in comparison with a conventional apparatus.

FIG. 8 is a diagram showing the influence of the spray angle (nozzle angle) of the paint supply nozzle (slit nozzle) on the peripheral speed of the pick-up roll in the third embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a spray angle (nozzle angle) of a paint supply nozzle (slit-shaped nozzle) in Example 3 of the above.

FIG. 10 is a view showing a widthwise flow velocity distribution in a paint pan in the vicinity of a pickup roll in comparison with a conventional device.

FIG. 11 is a schematic view showing a conventional general roll coater type coating apparatus.

FIG. 12 is a schematic view showing a conventional coating apparatus in which a guide member for partitioning a pickup roll side and an applicator roll side is provided in a paint pan.

FIG. 13 is a schematic view showing a conventional coating apparatus in which a raising nozzle for raising a coating liquid surface is provided in a paint pan.

FIG. 14 is a schematic view showing a conventional coating apparatus in which a chamber is provided at the end of a paint pan.

[Explanation of symbols]

 1 Pick-up roll 2 Applicator roll 3 Backup roll 4 Material to be coated 5 Paint pan 6 Paint 10 Paint supply nozzle 11 Discharge port 12 Paint supply system 12-1 Supply pump 12-2 Paint tank

Claims (3)

[Claims] 1. A roll coater type coating apparatus, comprising:
A paint supply nozzle, which is capable of spraying the paint uniformly in the roll width direction at an angle of 90 to 180 degrees with respect to the rotation direction of the roll, is provided in the paint pan on the exit roll peripheral surface side of the pick-up roll immersed in the paint. A coating device characterized by being placed. 2. A roll coater type coating apparatus, comprising:
A coating apparatus, wherein the coating material ejected from the coating material supply nozzle is uniform in the width direction of the roll and forms a streamline that is reverse to the rotation direction of the pickup roll. 3. A roll coater type coating apparatus, comprising:
The spray nozzle includes a paint supply nozzle for spraying paint onto the peripheral surface of the pickup roll so as to form a uniform streamline in the width direction of the pickup roll in the paint pan, and a paint supply system for supplying paint to the nozzle. A coating device characterized in that a paint discharge port in the paint pan is provided on the opposite side.