JP4905817B1 - Curtain coater, coating liquid guide - Google Patents

Abstract

To provide a curtain coater improved so that a coating liquid can be dropped into a curtain shape having a thickness smaller than that of a conventional one without supplying a lubricating liquid.
The coating liquid 30 formed in a curtain shape is dropped onto an object to be coated 70 by discharging the coating liquid 30 from a slit-shaped coating liquid discharge port 20 extending in the width direction. At the same time, in the curtain coater that coats the object to be coated 70 with the coating liquid 30, the thickness of both end portions 31, 31 of the coating liquid 30 formed in the curtain shape is the thickness of the central portion 32. Curtain coater characterized by its large size.
[Selection] Figure 1

Description

  The present invention relates to a curtain coater for forming a coating film that is thinner than conventional ones. Moreover, it is related with the coating-liquid guidance tool for curtain coaters used in order to form a thin coating film compared with the past.

  2. Description of the Related Art A curtain coater that forms a coating film on a coating object by passing the coating object under a coating liquid dropped into a curtain shape is used.

  By the way, the thickness of the coating film applied by the curtain coater is determined by the concentration of the coating liquid, the passing speed of the coating object, and the falling flow rate (discharge amount) of the coating liquid. Therefore, it is conceivable to adjust the thickness of the coating film to a desired thickness by changing these conditions.

  First, consider adjusting the thickness of the coating film by changing the concentration of the coating solution. If the other conditions are the same, if the coating solution concentration is large, the coating thickness formed on the coating will be large, and if the coating solution concentration is small, the coating formed on the coating will be formed. The thickness is also reduced. However, if the concentration of the coating solution is changed, the physical properties such as the viscosity of the coating solution also change, so that the adjustment range is limited. In addition, depending on the nature of the solvent for adjusting the concentration of the coating liquid, there is a possibility that the characteristics may change when a specific concentration is changed. Therefore, the concentration cannot always be adjusted to a desired concentration.

  As another method, it is possible to change the moving speed of the coated object by changing the moving speed of the article delivery table, and as a result, change the thickness of the coating film. If the moving speed of the article delivery table is increased, the amount per unit area of the coating liquid falling on the article to be coated is reduced, so that the coating thickness is reduced. However, if the moving speed is excessively increased, the coating film cannot be formed in time for the moving speed, and there is a possibility that uniform coating cannot be performed.

  Therefore, it is conceivable to reduce the thickness of the coating liquid dropped into the curtain shape by changing the falling flow rate of the coating liquid. If the falling flow rate of the coating liquid is reduced, the amount of the coating liquid falling on the object to be coated is reduced, so that the coating thickness is reduced. By this method, it is possible to adjust the thickness of the coating film to be applied without changing other requirements.

However, it is known that in order to drop the coating liquid while forming a curtain shape, it is necessary to drop it at a flow rate of a certain level or more. Although it depends on the properties of the coating liquid, if the flow rate is less than 1 cm ³ / sec per cm in the width direction of the coating liquid falling into the curtain shape (hereinafter simply referred to as “width direction”), the curtain It is said that it is difficult to drop into a shape. When the flow rate of the coating liquid is excessively decreased, for example, as shown in FIG. 6, both ends 131 and 131 of the coating liquid 130 formed in a curtain shape are inward in the width direction due to the action of surface tension. Therefore, a neck-in occurs in which the size d in the width direction decreases as it goes downward. In this state, not only the coating width becomes narrow, but also the falling state of the coating liquid becomes more unstable. For example, as shown in FIG. 7, the falling shape of the coating liquid may become a comb tooth shape 135. is there. When it becomes such a shape, it becomes impossible to form a coating film.

  Therefore, Patent Document 1 and Patent Document 2 present a technique relating to an edge guide of a curtain coater for neck-in prevention provided so as to sandwich both ends of a curtain formed of a coating liquid that flows downward. Has been.

  The edge guide presented in Patent Document 1 is provided with a lubricating liquid suction chamber having a lubricating liquid suction port mainly for sucking the lubricating liquid, and below the lubricating liquid suction chamber. And a paint suction chamber having a paint suction port that is opened in the vicinity and mainly sucks the paint, and the vacuum degree of the lubricant suction chamber and the vacuum degree of the paint suction chamber are controlled separately. . With this structure, even if the lubricating liquid is sucked by the lubricating liquid suction chamber at the lower end of the groove of the edge guide and the end of the paint curtain film is separated from the edge guide, the end of the paint curtain film is sucked by the paint. By strongly sucking in the chamber, the paint curtain film will not be necked in until the paint curtain film reaches the web, and the paint curtain film will be stable and will not cause thick coating of the edge of the web coating layer. Has been claimed.

  Further, the edge guide presented in Patent Document 2 is provided with a lubricating liquid supply port near the upper end of the inner surface and a lubricating liquid suction port near the lower end of the inner surface. The band-shaped area between the mouth and the lubricating liquid inlet is coated with a hydrophilic coating, and the areas on both sides of the band-shaped area with the hydrophilic coating on the inner surface are water-repellent coating It is characterized by that. In addition, the latter can prevent the curtain film neck-in of the paint film with a smaller amount of lubricating liquid than before, and by forming a uniform and thin lubricating liquid film on the inner surface of the edge guide, the stability of the curtain film is improved, It is claimed that since the amount of the lubricating liquid is small, the suction device for collecting the lubricating liquid can be simplified and the waste paint can be reduced.

JP 2009-136752 A JP 2009-172471 A

  However, the techniques of Patent Document 1 and Patent Document 2 both attempt to prevent neck-in by supplying a lubricating liquid separately from the coating liquid. According to this configuration, since at least two systems of supply lines composed of the coating liquid and the lubricating liquid are required, the structure becomes complicated. Further, since it becomes necessary to adjust the supply amount, the flow rate management becomes complicated, so that a high skill is required for the operation of the curtain coater.

  The present invention has been made in view of such circumstances, and a curtain coater improved so that the coating liquid can be dropped into a curtain shape having a smaller thickness than the conventional one without requiring supply of a lubricating liquid. It is to provide. Moreover, it is providing the jig for curtain coaters which has the same function.

  The curtain coater according to the present invention drops the coating liquid formed in a curtain shape onto an object to be coated by discharging the coating liquid from a slit-shaped coating liquid discharge port extending in the width direction. In the curtain coater that coats the object to be coated with the coating liquid, the thickness of both ends of the coating liquid formed in the curtain shape is larger than the thickness of the central part. And

  According to the present invention, since the thickness of both ends of the coating liquid formed in the curtain shape is larger than the thickness of the central portion, the flow rate of the coating liquid at both ends is larger than that of the central portion. As a result, since the influence of the surface tension acting on both ends can be relatively reduced, the effect of pulling both ends to the center can be suppressed. Therefore, the occurrence of neck-in in which the size of the curtain shape in the width direction becomes narrower as it goes downward is suppressed.

  In the curtain coater according to the present invention, the curtain shape is preferably formed such that the size between both ends of the curtain shape is smaller than the size in the width direction of the coating liquid discharge port.

  According to the present invention, since the curtain shape is formed so that the size in the width direction of the curtain shape is smaller than the size in the width direction of the coating liquid discharge port, both ends of the coating liquid falling into the curtain shape are formed. The thickness can be easily increased as compared with the thickness of the central portion.

  In the curtain coater according to the present invention, it is preferable that the diameter of both ends of the coating liquid discharge port is larger than the diameter of the central portion.

  According to the present invention, since the diameters of both ends of the coating liquid discharge port are larger than the diameter of the central part, the flow rate of the coating liquid at both ends is larger than that of the central part.

  The curtain coater according to the present invention preferably includes a coating liquid guiding portion that guides the coating liquid discharged from both ends of the coating liquid discharge port inward in the width direction.

  According to the present invention, since the coating liquid discharged from both ends of the coating liquid discharge port is guided inward in the width direction, the guided coating liquid is supplied to both ends of the curtain shape. . As a result, the flow rate of the coating liquid at both ends is larger than that at the center. Therefore, since the influence of the surface tension acting on both ends can be made relatively small, the effect of pulling both ends to the center can be suppressed. Therefore, the occurrence of neck-in in which the size of the curtain shape in the width direction becomes narrower as it goes downward is suppressed.

  The curtain coater according to the present invention preferably further includes an edge guide disposed so as to be in contact with both ends of the coating liquid formed in a curtain shape.

  According to the present invention, the occurrence of neck-in is further suppressed by the edge guides coming into contact with both ends of the coating liquid formed in a curtain shape.

  The coating liquid guide according to the present invention is an object to be coated with the coating liquid formed in a curtain shape by discharging the coating liquid from a slit-shaped coating liquid discharge port extending in the width direction. And a curtain coater that coats the object to be coated with the coating liquid. The coating liquid guide is disposed so as to be in contact with both ends of the coating liquid formed in a curtain shape, and the coating liquid discharged from both ends of the coating liquid discharge port. Is guided to the center side.

  According to the present invention, the coating liquid formed in the curtain shape is coated by using the coating liquid guide that guides the coating liquid discharged from both ends of the coating liquid discharge port to the center side. It is possible to suppress the occurrence of neck-in in the curtain coater that drops the workpiece and coats the workpiece with a coating liquid. Moreover, if it is a curtain coater which has a structure which can arrange | position this coating-liquid guidance | induction tool, generation | occurrence | production of a neck-in can be suppressed irrespective of other structures. For example, if the coating liquid guiding tool is configured to be removable, an effect of suppressing the occurrence of neck-in can be generated as necessary.

  According to the curtain coater according to the present invention, it is possible to suppress the occurrence of neck-in in which the width of the curtain shape becomes narrower as it goes downward, so that the supply of lubricating liquid is not involved, compared to the conventional case. The coating liquid can be dropped into a curtain shape with a small thickness.

FIG. 1 is a partial cross-sectional perspective view showing the curtain coater of the first embodiment. FIG. 2 is a schematic view seen from the side of the curtain coater of the same embodiment . FIG. 3 is a front view showing a method of implementing the curtain coater of the reference form. FIG. 4 is a partial sectional perspective view showing a modified example of the curtain coater. FIG. 5 is a perspective view showing another modified example of the curtain coater. FIG. 6 is a partially sectional perspective view showing an example of a conventional curtain coater, which shows a curtain coater in which neck-in occurs. FIG. 7 is a partially sectional perspective view showing an example of a conventional curtain coater, which shows a curtain coater in which a comb-shaped coating liquid has dropped.

[First Embodiment]
Hereinafter, a curtain coater according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In the following description, the direction and direction described in FIG. 1 are used for the direction and direction.

FIG. 1 is a perspective view for explaining the outline of a curtain coater.
The curtain coater has a pump P for supplying a coating liquid, a curtain forming unit 1 for forming the coating liquid 30 supplied by the pump P into a curtain shape, and a coating to be delivered for coating an object to be coated. The product delivery table 60 is provided.

  A smooth coating liquid table 10 is formed on the upper part of the curtain forming unit 1 so that the rear side is higher than the front side. Further, the coating liquid table 10 is provided with a slit-shaped coating liquid discharge port 20 extending in the width direction. The coating liquid 30 discharged from the coating liquid discharge port 20 flows on the coating liquid table 10 while forming a film having a uniform thickness, and falls from the front end 11 of the coating liquid table 10. A curtain-shaped coating liquid 30 is formed. Since the front end portion 11 of the coating liquid table 10 is smoothly curved downward, the coating liquid 30 falls downward while forming a curtain shape without breaking the formed film shape.

  Below the front end 11 of the coating liquid table 10, a coating liquid guiding section 15 that guides the coating liquid 30 discharged from both end portions 21 and 21 of the coating liquid discharge port 20 inward in the width direction. Is provided. More specifically, the coating liquid guiding section 15 is provided with coating liquid guiding tools 50 and 50 that are separate from the curtain coater main body, below the front end 11 of the coating liquid table 10 and outside in the width direction. It is formed by arrange | positioning to each. The coating liquid guiding tool 50 has a smooth slope 51 projecting inward in the width direction from above to below, and the outer end 31 in the width direction of the curtain shape is in contact with the slope 51. Arranged. Since the coating liquid 30 at both ends 31, 31 is guided inward by dropping the curtain-shaped both ends 31, 31 along the inclined surfaces 51, 51, the width of the coating liquid discharge port 20 is increased. The size d in the width direction of the curtain shape is smaller than the size D. As a result, since the induced coating liquid falls, the thickness of the curtain-shaped end portions 31 and 31 becomes thicker than that of the central portion 32. That is, the flow rate of the coating liquid at both ends 31, 31 of the curtain shape is larger than that at the center portion 32.

As already described, in the curtain coater, if the flow rate of the coating liquid 30 is excessively reduced, neck-in occurs, and further, when the transition to the comb-shaped drop occurs, it is impossible to apply the coating. Become. This neck-in occurs because the flow rate of the coating liquid flowing at both ends of the curtain shape is small and the influence of the surface tension becomes relatively large with respect to the influence of gravity. Therefore, generation | occurrence | production can be suppressed by making the flow volume of the coating liquid 30 of the both ends 31 and 31 increase. Specifically, if the flow rates at both ends 31, 31 are equal to or higher than the flow rate at which neck-in occurs, neck-in does not occur. In this case, it is not always necessary to increase the flow rate at the center. Therefore, the neck-in does not occur even if the flow rate of the central portion 32 is lower than the flow rates of the end portions 31 and 31 (for example, a flow rate of less than 1 cm ³ / sec per 1 cm). Moreover, the comb-shaped drop does not occur. That is, by using this cartan coater, it is possible to reduce the flow rate of the central portion 32 as compared with the conventional one while suppressing the fall of the neck-in and comb teeth. As a result, a thinner coating can be achieved than in the prior art.

  An edge guide 40 is disposed below the coating liquid guiding portion 15 so as to be in contact with both end portions 31 and 31 of the coating liquid 30 formed in a curtain shape. More specifically, the edge guide 40 has a liquid contact surface 41 that is a smooth surface extending in the vertical direction, and the liquid contact surface 41 has both end portions 31, 31 in the width direction of the coating liquid 30. It is provided so that it may touch. By dropping the coating liquid 30 at both end portions 31 and 31 along the liquid contact surface 41 of the edge guide 40, the occurrence of neck-in can be further suppressed.

  Below the edge guide 40, there is provided an object delivery table 60 on which paper 70 as an object to be coated is loaded and moved in the front-rear direction. More specifically, as shown in FIGS. 2 (a) and 2 (b), the article delivery table 60 is a belt conveyor for moving the loaded paper 70 by the power of the motor. By moving the object to be coated from the rear to the front of the belt conveyor, the curtain-shaped coating liquid 30 is applied to the object to be coated, whereby a coating film 35 is formed.

Coating with this curtain coater is performed as follows.
As shown in FIG. 2A, by first operating the pump P, the coating liquid 30 is supplied to the curtain forming unit 1 from a coating liquid tank (not shown). The coating liquid 30 is discharged from the coating liquid discharge port 20, flows on the coating liquid table 10, and falls from the front end portion 11 of the coating liquid table 10. The dropped coating liquid 30 is received by the liquid receiver 80 and returned to the above-described coating liquid tank. In this state, the flow rate of the coating liquid 30 is adjusted so that the coating liquid 30 falls in a curtain shape.

  When the falling coating liquid 30 forms a curtain shape and the shape is stabilized, the flow rate of the coating liquid is further adjusted so as to obtain a flow rate at which a coating film 35 having a desired thickness can be obtained. At the same time, the supply of the paper 70 that is the object to be coated is started by operating the object delivery table 60. After confirming that both the flow rate of the coating liquid 30 and the supply of the paper 70 are stable, the curtain forming unit 1 is moved forward as indicated by the arrows.

  As shown in FIG. 2 (b), the coating liquid 30 formed in a curtain shape falls on the paper 70 by the movement of the curtain forming unit 1, so that the coating is started. By appropriately adjusting the supply speed of the paper 70 and the flow rate of the coating liquid 30, a coating film 35 having a desired thickness is formed on the paper 70. When finishing the coating, as shown by the arrow, after the curtain forming unit 1 is moved backward, the paper supply and the coating liquid supply are stopped in order.

  According to the present embodiment described above, the following effects can be obtained.

  (1) In the present embodiment, the coating liquid 30 discharged from the both end portions 21 and 21 of the coating liquid discharge port 20 is guided inward in the width direction by the action of the coating liquid guiding section 15. The induced coating liquid 30 is supplied to both end portions 31 and 31 of the curtain shape. As a result, the flow rate of the coating liquid at both end portions 31 and 31 is larger than that at the central portion 32. Therefore, since the influence of the surface tension acting on both end portions 31 and 31 can be relatively reduced, the effect of attracting both end portions 31 and 31 to the center can be suppressed. Therefore, generation | occurrence | production of the neck in which the magnitude | size of the width direction of a curtain shape becomes narrow, and the fall of a comb-tooth shape are suppressed as it goes below.

  (2) In the present embodiment, since the coating liquid guiding part 15 is realized by the separate coating liquid guiding tool 50, the occurrence of the neck-in can be suppressed as necessary. In addition, if the coating liquid guide 50 can be attached, it is possible to suppress the occurrence of the neck-in and the drop of the comb tooth shape even in a conventional curtain coater.

  (3) In this embodiment, since the curtain coater is provided with the edge guide 40 for preventing neck-in, the occurrence of neck-in and the comb tooth shape in which the width of the curtain shape becomes narrower as it goes downward. Is further suppressed.

[ Reference form]
Hereinafter, a curtain coater according to a reference embodiment of the present invention will be described with reference to FIG. In addition, since a reference form is the form which changed the form of the curtain formation part in 1st Embodiment, it attaches | subjects the same code | symbol to the part provided with the same function, and abbreviate | omits the description.

  FIG. 3 is a front view for explaining the form of the curtain forming portion 1 of the curtain coater. A smooth coating liquid table 10 is formed on the upper part of the curtain forming unit 1 so that the rear side is higher than the front side. Further, the coating liquid table 10 is provided with a slit-shaped coating liquid discharge port 20 extending in the width direction.

In this reference embodiment, the coating liquid discharge port 20 diameter r1 of the both end portions 21 and 21 than the diameter r2 of the central portion 22 is large. Therefore, the flow rate of the discharged coating liquid 30 also increases toward both ends. As a result, the thickness of the film of the coating liquid 30 formed on the coating liquid table 10 is also larger than the center portion 32, and the both end portions 31 are larger than the front end portion 11 of the coating liquid table 10. By doing so, the thickness of the curtain-shaped coating liquid 30 to be formed is larger at both end portions 31 and 31 than at the central portion 32.

According to the reference embodiment described above, the following effects can be obtained.

  (1) Since the thickness of both ends 31 and 31 of the coating liquid 30 formed in the curtain shape is larger than the thickness of the central portion 32 in the same direction, the both end portions 31 and 31 are compared with the central portion 32. The coating liquid flow rate increases. As a result, since the influence of the surface tension acting on both end portions 31 and 31 can be relatively reduced, the effect of attracting both end portions 31 and 31 to the center can be suppressed. Therefore, the occurrence of neck-in in which the size of the curtain shape in the width direction becomes narrower as it goes downward is suppressed.

In addition, you may change the said 1st Embodiment and reference form as follows.

In the first embodiment and the reference embodiment, one coating liquid discharge port 20 is provided, but a plurality of coating liquid discharge ports may be provided. For example, as shown in FIG. 4, if the curtain forming unit 1 includes two coating liquid discharge ports 20a and 20b, two layers of coating can be performed in one coating process. Even in this case, the occurrence of neck-in can be prevented by forming the curtain shape of the coating liquid 30 so that the thickness of the curtain-shaped end portions 31 and 31 is larger than the thickness of the central portion 32 in the same direction. Can be suppressed. Moreover, the curtain formation part 1 may be provided with the 3 or more coating liquid discharge outlet.

-In the above-mentioned reference form, although the coating liquid guidance | induction part 15 and the edge guide 40 are not provided, you may provide at least any. In addition to the shape of the coating liquid discharge port 20, if it has such a configuration, the effect of suppressing the occurrence of neck-in can be further increased.

In the first embodiment and the reference embodiment, the coating liquid table 10 is provided, and after the coating liquid film is formed on the coating liquid table 10, the coating liquid 30 is dropped into a curtain shape. Although the present invention is applied to a curtain coater, it may be applied to other types of curtain coaters. For example, as shown in FIG. 5, the present invention may be applied to a curtain coater that forms a curtain-shaped coating liquid 30 by dropping the coating liquid 30 directly downward from the coating liquid discharge port 20.

In the first embodiment and the reference embodiment, the coating liquid guiding unit 15 is formed by the coating liquid guiding tool 50, but may have other configurations. For example, the coating liquid guiding part 15 may be formed by extending the upper end of the edge guide 40 upward, or may be provided directly on the curtain forming part 1. In this case, since it is not necessary to use a separate coating liquid guide 50, the number of parts can be reduced. In short, as long as the coating liquid 30 discharged from the both ends 21 and 21 of the coating liquid discharge port 20 is guided inward, the same operation is performed regardless of the form of the coating liquid guiding section 15. Has an effect.

DESCRIPTION OF SYMBOLS 1 Curtain formation part 10 Coating liquid table 11 Front end part 15 Coating liquid guidance | induction part 20 Coating liquid discharge outlet 20a Coating liquid discharge outlet 20b Coating liquid discharge outlet 21 End part 22 (of coating liquid discharge outlet) Central part 30 of coating liquid discharge port Coating liquid 31 End part 32 (of coating liquid) Central part 35 (of coating liquid) Coating film 40 Edge guide 41 Liquid contact surface 50 Coating liquid guide (coating) Engineering fluid guiding part)
51 Slope 60 Workpiece delivery table 70 Paper (workpiece)
80 liquid receiver 130 coating liquid 131 end 135 comb tooth shape P pump r1 caliber r2 caliber

Claims (4)

By discharging the coating liquid from the slit-shaped coating liquid discharge port extending in the width direction, the coating liquid formed in a curtain shape is dropped onto the coating object and the coating object is In the curtain coater to be coated with the coating liquid,
The thickness of both end portions of the coating liquid formed in the curtain shape is larger than the thickness of the central portion,
The curtain shape is formed so that the size between both ends of the curtain shape is smaller than the size in the width direction of the coating liquid discharge port,
A coating liquid guide part for guiding the coating liquid discharged from both ends of the coating liquid discharge port inward in the width direction;
A curtain coater in which the coating liquid guiding part is detachable from the curtain coater body .   The curtain coater according to claim 1, wherein the diameter of both ends of the coating liquid discharge port is larger than the diameter of the central portion.   The curtain coater according to claim 1, further comprising an edge guide disposed so as to be in contact with both ends of the coating liquid formed in a curtain shape. The coating liquid formed in a curtain shape is dropped onto the object to be coated by discharging the coating liquid from the slit-shaped coating liquid discharge port extending in the width direction, and the object to be coated is Used for curtain coaters to be coated using the coating liquid,
It is detachable from the curtain coater,
A coating for guiding the coating liquid discharged from both ends of the coating liquid discharge port to the center side while being disposed in contact with both ends of the coating liquid formed in a curtain shape. Industrial fluid guide.

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