JPH05154436A - Coating method by roll coater - Google Patents

Abstract

PURPOSE:To provide a simple means capable of executing an uniform and fine coating free from unevenness of a coated film in one face coating or both face coating in the coating of roll-coater system. CONSTITUTION:In the coating of a belt like material with a roll coater, a leveling roll 11 (heat roll is preferably used) is pressed on an unhardened liquid coated film transferred on the surface of the belt like material 7 with an applicator roll 5 to generate a roll grain, easily smoothed by surface of the coated film and the sufficient smoothed coated film is obtained before reaching a drying furnace. And, in the case of a both face coating, vibration of the belt like material 7 at the time of back face coating is suppressed by providing the applicator roll 5 of a roll coater for back face coating in an opposite position against the leveling roll 11 with the interposed belt like material 7 and as a result, the smoothed both face coating is executed in a stable condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a belt-shaped material using a roll coater.

[0002]

2. Description of the Related Art Conventionally, a "coating method using a roll coater" has been the mainstream as a method for continuously applying a coating solution to a strip-shaped material such as a steel plate, and many related techniques have been proposed. Suggestions have also been made.

For example, FIG. 3 is a schematic view of a typical example of a conventional roll coater, in which a pickup roll 3 is arranged with a part thereof being immersed in the paint 2 contained in a paint pan 1. In addition, the metering roll 4 is attached to the "roller peripheral surface part which comes out of the paint 2 and rotates upward" of the pickup roll 3.
However, the application roll 5 is spaced apart from the metering roll 4 by a predetermined distance in the circumferential direction of the pickup roll.
, Respectively, are opposed to each other at a slight distance or in a pressed state. In addition,
The applicator roll 5 is opposed to the surface of the belt-shaped material 7 wound around the backup roll 6 and transferred.

Now, the coating on the belt-shaped material by the roll coater is performed as follows. That is, the pick-up roll 3 around which the paint 2 in the paint pan 1 is attached is in the middle of the mail.
After adjusting the amount of paint adhered by the taling roll 4,
The remaining adhered paint is transferred to the applicator roll 5. Next, the application roll with the paint transferred and attached.
The roll 5 transfers / applies the adhered paint onto the surface of the strip-shaped material 7 which is wound around the backup roll 6 and transferred. After that, the band-shaped material 7 is transferred to a drying furnace and the attached paint is dried and cured.

However, in such a roll coater type coating, as shown in FIG.
The ridge-like irregularities called "roll-eye" as shown in FIG. The rolls are caused by the instability of the paint flow between the rolls constituting the roll coater, but they remain after the drying oven and cause serious defects on the surface of the coating film. leave.

Further, in the case of coating both sides of the strip-shaped material by a roll coater type coating method, another roll is provided at the downstream position of the usual roll coater (for one side coating).
The rucotor is placed facing the backside of the strip, and this combination is used for double-sided coating, but the backside roll must be used to hold the strip-shaped material because it is necessary to protect the coated surface during backside coating. Therefore, the running belt-like material is likely to vibrate, and the unevenness as shown in FIG. 5 occurs on the back side coating film surface in the direction perpendicular to the traveling direction of the belt-like material. The defects tended to be similar to those in the eyes.

However, as Japanese Patent Publication No. 57-36024, a roll-shaped material is arranged at the same position on the front and back of the strip-shaped material, and the strip-shaped material is sandwiched between the applicator rolls of both roll coaters. There is a proposal to perform double-sided coating. Then, according to this proposal, it is considered that the vibration of the belt-shaped material at the coating position is suppressed and the above-mentioned problem is avoided, but when actually adopting this means, only the same paint on the front and back can be used, and It was difficult to paint under optimal conditions on both sides.

By the way, as a measure for preventing the occurrence of the above-mentioned "roll eye", for example, the following proposals have been made. In the proposal as Japanese Patent Application Laid-Open No. 63-143962, a roll coater structure is devised so that the transfer roll 8 is provided with a required gap in the applicator roll 5 as shown in FIG. And the transfer roll 8
, A doctor roll 9 is placed close to it with a required gap,
Further, the roll coater is constructed such that the blade 10 is in contact with the doctor roll 9 so that the cutting edge is in contact therewith. The rotation directions of the three rolls other than the pickup roll 3 and the backup roll 6 are the same.

In the roll coater proposed above, three rolls other than the pickup roll 3 and the backup roll 6 are rotated in the same direction so that the paint between the rolls is coated. At the same time as preventing the flow instability phenomenon,
The applicator roll 5 is supplied with double coating material from the pickup roll 3 and the transfer roll 8 to prevent uneven coating of the coating material and to achieve uniform coating.

However, it is generally difficult to adjust the thickness of the coating film by reverser coating in which the rolls rotate in the same direction, and when the number of rolls is large, it is not complicated to set the operating conditions. Because of the unavoidable circumstances, the above proposal cannot be said to be fully satisfactory in practice.

[0011] Further, a proposal of a roll coater for preventing roll eyes can be seen in Japanese Patent Laid-Open No. 63-143961. In this proposal, as shown in FIG. 7, "blade 10 for guiding the flowing paint flow to the application roll".
Is arranged so that the lower end is close to the surface of the applicator roll 5, and the transfer roll 8 is arranged in contact with the upper end of the blade 10, and further the transfer roll 8 is arranged.
A doctor that rotates in the same direction as the doctor
A roll coater structure in which rolls 9 are closely arranged is disclosed, and it is intended to suppress an unstable phenomenon of paint flow between the rolls and perform uniform coating.

However, this means is also disclosed in JP-A-63-143.
As in the case of the proposal of No. 962, it is difficult to control the thickness of the coating film, and the paint flows down the blade surface, so that it is impossible to apply high viscosity paint. From
After all it was not completely satisfactory.

Therefore, the object of the present invention is to coat the belt-shaped material by the roll coater method.
It was to establish a simple means that can carry out uniform and beautiful coating without causing unevenness of the coating film such as roll eyes regardless of whether the coating is on one side or both sides.

[0014]

The present invention has been completed based on the results of research by the present inventor conducted while repeating many experiments to achieve the above object,
"When applying a strip material using a roll coater, the leveling roll is pressed against the liquid coating film before curing, which was transferred to the surface of the strip material by the applicator roll. It has a major feature in that "rolled eyes having a form that is easily smoothed by the surface tension of (3) are generated on the coating film surface, and the coating film surface is sufficiently smooth by the time it reaches the drying furnace." Rolls for backside coating are placed at opposite positions sandwiching the strip-shaped material of the leveling roll.
By arranging the applicator roll of the rucotor, it is possible to suppress the vibration of the belt-shaped material at the time of coating the back surface, and thereby it is possible to perform smooth double-sided coating in a stable situation. " Is.

Here, it is preferable that the leveling roll is configured to be fixed or rotate at a required speed according to the conditions such as the type of coating material and the coating speed. To produce a smooth surface by generating "rolling rolls with a short cycle" that are more likely to be leveled by surface tension than roll rolls that cannot avoid being generated between the roll and the metering roll. Planned.

When the coating is carried out according to these methods, the leveling roll is used as a heating roll (electrothermal heating roll, etc.), and the physical properties of the coating film are controlled by heating with this leveling roll (coating film). Viscosity reduction).
Smoothing of the coating film by the action of surface tension is promoted more smoothly, which is preferable.

Hereinafter, the present invention will be described in detail with its operation based on the drawings.

1 is an explanatory view of an example of a coating method according to the present invention. The roll coater shown in FIG. 1 is not different from the conventional roll coater, and the paint 2 pulled up from the paint pan 1 by the pick-up roll 3 is an application provided in contact with the pick-up roll 3. -Transfer to the roll 5 and then the film thickness is adjusted by the metering roll 4 arranged close to the applicator roll 5, and then transferred to the strip 7 on the backup roll 6. To be done.
At this time, rolls generated between the rolls remain on the strip-shaped material.

The present invention is characterized in that the leveling roll 11 is arranged at the downstream position of the applicator roll 5. The leveling roll 11 installed so as to be in contact with the coating film on the strip-shaped material 7 is a roll generated by the applicator roll 5 or the metering roll 4 before the liquid coating surface before curing. -A roll eye having a size (cycle) different from that of the roll eye is generated.

The cycle of the roll eyes generated at this time varies depending on the number of rotations of the leveling roll 11, but if the number of rotations is properly selected, the roll eyes of a very short cycle can be generated. .. The effect of the surface tension acting on the coating film before curing becomes more remarkable as the rolling cycle becomes shorter, and the "leveling effect due to the flow of the coating film" is significantly improved to obtain a smooth coating film surface. Be done.

In this case, if a heating roll having a heating element installed therein is used as the leveling roll 11, the strip 7
As described above, it is possible to reduce the viscosity of the coating material (coating film) applied on the upper surface to improve the fluidity and further improve the leveling effect.

If back coating is also required, the coating method shown in FIG. 2 is preferably used. That is, in FIG.
It is explanatory drawing regarding the other example of the coating method which concerns on this invention, Although surface coating is implemented like the case shown in FIG. 1, the roll coater for back surface coating (The thing illustrated in FIG. (A pickup roll 3'and an applicator roll 5'applied with the paint 2'in the paint pan 1 '), the applicator roll 5'position is the strip 7 Another feature is that the back side is coated by arranging it so as to be opposed to the leveling roll 11 with sandwiching it therebetween. If the back surface is coated with such a roll arrangement, the surface of the belt-shaped material 7 is supported by the leveling roll 11, so that the belt-shaped material can be contacted with the applicator roll 5'for back surface coating. No vibration is generated in this portion of No. 7, and damage to the coating film on the already applied surface is prevented as in the case where a normal backup roll is newly installed, and coating is performed under suitable conditions. be able to.

[0022]

【Example】

Example 1 A roll coater as shown in FIG. 1 having the following respective dimensions was prepared. Applicator roll diameter: 300mm, Pickup roll diameter: 300mm, Metering roll diameter: 150mm, Backup roll diameter: 800mm, Leveling roll (10mm thick rubber lining Diameter): 150 mm.

First, without applying the leveling roll, the peripheral speed ratio of each roll is calculated as "line speed: applicator roll peripheral speed: pickup roll peripheral speed = 1: 1.4: 0.25".
, And the coating roll with static viscosity of 500 cp and surface tension of 34 dyn / cm was applied to the strip material (steel strip) by changing the line speed and film thickness. It was

At this time, the surface condition of the coating film (size of rolls) in the initial wet state and the dried state of the coating film was measured. The results are shown in Table 1.

[0025]

[Table 1]

The following can be seen from the results shown in Table 1. That is, when the conditions of line speed and film thickness are A to E, the leveling of the coating film is incomplete and rolls remain as surface defects. It occurs, and it appears as a defect on the surface of the coating film.

Then, a leveling roll was then applied, and a coating test was conducted under the same conditions as above except for the above. In this test, the number of rotations of the leveling roll was changed variously, and the condition of the coating film surface after drying was examined. At this time, the amount of the leveling roll pushed into the coating film was visually adjusted so that the roll had an appropriate amount so as not to scrape off the coating material. The test results are shown in Table 2.

[0028]

[Table 2]

As is clear from the results shown in Table 2, when the leveling roll is applied according to the present invention, the height of surface irregularities due to the rolls after drying is submicron in most conditions. It became an order, and the leveling effect was obtained so that the surface defects could not be visually observed. Further, it can be seen that the unevenness under the condition of the paint supply condition G is smoothed by applying the leveling roll to obtain a uniform coating film.

[Embodiment 2] A leveling roll having an electric heater installed therein is applied, and the surface temperature of the roll is always 5
A coating test was performed on the belt-shaped material under the same conditions as in Example 1 except that the temperature was controlled to 0 ° C. The paint used here is of the type whose viscosity decreases with increasing temperature,
When the coating temperature was around 50 ° C, it was about 1/2 of the initial viscosity at room temperature (25 ° C). Then, the surface condition of the coating film after drying was examined through this test. The test results are shown in Table 3.

[0031]

[Table 3]

As is clear from the results shown in Table 3, in the case of using the heating leveling roll, all the operating conditions were compared with the case of Example 1 using the room temperature leveling roll. It can be seen that the leveling effect is improved by 10 to 15%.

[Example 3] A roll coater as shown in Fig. 2 having the following dimensions was prepared in order to coat both sides of a strip material (steel strip). Applicator roll (both) diameter: 300mm, Pickup roll (both) diameter: 300mm, Metering roll diameter: 150mm, Backup roll diameter: 800mm, Leveling roll (Thickness 10 mm with rubber lining) Diameter: 150 mm. In addition, as shown in the figure, no metering roll was provided on the back coating roll coater.

Then, the peripheral speed ratio of each roll (both front and rear roll coaters) is defined as "line speed: applicator roll peripheral speed: pickup roll peripheral speed = 1: 1.4: 0.25". And a coating roll having a viscosity of 500 cp and a surface tension of 34 dyn / cm was applied to both sides of the strip at various line speeds with the metering roll stationary. By the way, in this test,
The comparative example data not using the level and the example data of the present invention to which the leveling roll was applied were obtained. When the leveling roll was applied, the leveling was performed as in the case of Example 1. The amount of the roll pushed into the coating film was visually adjusted so that the roll did not scratch the paint.

Table 4 shows "data comparing the unevenness of the coating film surface after drying the back surface with and without the application of the leveling roll" obtained by the above test.

[0036]

[Table 4]

As is clear from the results shown in Table 4, when the leveling roll was not applied, the unevenness of the back coating surface increased with the increase of the line speed, but the leveling roll was increased. It can be seen that when is installed, the surface irregularities hardly change at low line speeds. This is because when the leveling roll was installed, no harmful vibration of the strip material occurred at the roll coater position for back side coating even during high speed coating, and thus a smooth back side coated surface was obtained. It is due to.

[0038]

[Summary of Effects] As described above, according to the present invention, "roll eyes" which are apt to occur in the coating of the belt-shaped material by the roll coater method regardless of the one-side coating or the both-side coating.
The unevenness of the coating film surface is easily and properly suppressed, and even if high-speed coating is carried out, a smooth and beautiful coated surface can be stably realized, and industrially useful effects are brought about.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example of a coating method according to the present invention.

FIG. 2 is a diagram illustrating another example of the coating method according to the present invention.

FIG. 3 is an explanatory view of a conventional roll coater type coating method.

FIG. 4 is an explanatory diagram of rolls generated in a roll coater type coating.

FIG. 5 is an explanation regarding the uneven pattern of the coating film which occurs on the back surface when double-sided coating is performed by the roll coater method.

FIG. 6 is an explanatory view of a conventional roll coater type coating method.

FIG. 7 is an explanatory view of another conventional roll coater type coating method.

[Explanation of symbols]

 1 Paint pan 1'Paint pan 2 Paint 2'Paint 3 Pickup roll 3'Pickup roll 4 Metering roll 5 Applicator roll 5'Appliment roll 6 Backup roll 7 Strip material 8 Transfer roll 9 Doctor roll 10 Blade 11 Leveling roll

Claims (3)

[Claims] 1. A method for coating a belt-shaped material using a roll coater, wherein a leveling roll is pressed against a liquid coating film before curing which has been transferred to the surface of the belt-shaped material by an applicator roll, thereby applying the coating material. A method for coating with a roll coater, characterized in that rolls having a shape that is easily smoothed by the surface tension of the film are generated on the surface of the coating film. 2. The roll coater according to claim 1, wherein the leveling roll is a heating roll, and the physical properties of the coating film are also controlled by heating with the leveling roll. How to paint. 3. An applicator roll of a roll coater for backside coating is arranged at opposing positions sandwiching the strip-shaped material of the leveling roll, and the backside coating is also performed on the strip-shaped material.
A coating method using the roll coater according to claim 1.