WO2013140620A1

WO2013140620A1 - Curtain coater

Info

Publication number: WO2013140620A1
Application number: PCT/JP2012/057585
Authority: WO
Inventors: 敏弘片野; 弘幸河野; 明男平野; 忠佐々; 克己石塚
Original assignee: フォイトパテントゲゼルシャフトミットベシュレンクテルハフツング
Priority date: 2012-03-23
Filing date: 2012-03-23
Publication date: 2013-09-26

Abstract

Provided is a curtain coater capable of forming a curtain film that is uniform in the transverse direction even when the coating is made to flow downward at a low flow rate with the curtain coater. A curtain coater (1), which is formed to be long in the transverse direction of a substrate (60) that is to be coated, which has a coating chamber (10) that extends in said transverse direction, in which a coating (30) for coating is supplied into the coating chamber (10), and which is provided with a curtain coater head (2) that causes the coating to flow downward as a curtain film (12). The curtain coater is provided with a guide plate (24), which guides a low viscosity liquid (40) with a viscosity lower than the coating (30) to the vicinity of the substrate (60) while in contact with the low viscosity liquid (40).

Description

Curtain coating machine

The present invention relates to a curtain coating machine for applying a paint to a substrate by flowing a paint into a curtain film.

Conventionally, a curtain coating machine (DF (Direct Fountain) coater) for forming a coating film on a tape-like substrate such as paper is known. This curtain coating machine smoothly guides the defoamed paint supplied to the head for the curtain coating machine to the lower nozzle part without stagnation, and the nozzle part rectifies the flow of paint uniformly in the width direction. Flow down from the nozzle tip. The paint that has flowed down is formed into a uniform and stable curtain film shape, and is supplied onto a substrate that travels at a high speed (see, for example, Patent Document 1).

JP 2000-210607 A

The above curtain coating machine is excellent in that it can be applied at high speed without using wasteful paint. However, when the coating material is caused to flow down at a low flow rate, it is difficult to form a curtain film that is uniform in the width direction at, for example, about 3 L / min / m or less. Further, since an air flow is generated in the curtain film when the substrate is run at a high speed, it is difficult to maintain the curtain shape by the air flow when the flow rate is low.

On the other hand, there is also known a die coater for applying the nozzle portion close to the substrate. In this die coater, since the paint sprayed from the nozzle directly hits the substrate, it can be applied without forming the curtain film described above, but due to the problem of the paint stretch rate, it can only be applied at very low speeds. There is.

The present invention has been made in view of the above-described circumstances, and is a curtain coating machine capable of forming a uniform curtain film in the width direction even when the paint is allowed to flow down at a low flow rate with the curtain coating machine. It is for providing.

In order to solve the above-described problems, the present invention has a paint chamber which is formed in a long shape along the width direction of a substrate to be coated and extends in the width direction. In a curtain coating machine provided with a curtain coating machine head that flows down the paint in the form of a curtain film, the low viscosity liquid is brought into contact with a low viscosity liquid having a viscosity lower than that of the paint. A guide plate is provided for guiding to the vicinity of the substrate.

Also, a low-viscosity liquid chamber can be provided inside the curtain coating machine head for storing the low-viscosity liquid and flowing it downward.

Furthermore, the low-viscosity liquid may be a dilute solution obtained by diluting the paint, an aqueous solution such as a surfactant, or water.

In the curtain coating machine according to the present invention, a guide plate is provided for guiding the low viscosity liquid to the vicinity of the base material while being in contact with the low viscosity liquid having a viscosity lower than that of the paint. A paint curtain film can be formed on the opposite side of the curtain film. Therefore, the curtain film can flow down in a state where the viscosity resistance is low as compared with the case where the paint is in direct contact with the guide plate. As a result, the deceleration phenomenon of the paint at the interface between the curtain and the plate due to viscous resistance is reduced, and the curtain becomes close to free fall. Accordingly, the curtain film can be accelerated to an appropriate speed, defects such as coating film skip can be prevented, and coating can be performed while traveling at a higher speed. In addition, since the paint near the interface is hardly decelerated, there is no speed difference between the paint near the interface and the surface side, and the phenomenon of the curtain undulating can be prevented. Furthermore, for example, even at a low flow rate of less than 3 L / min / m, since a uniform curtain film is formed in the width direction, the coating film to be coated on the substrate can be made thin.
Also, compared to a normal curtain coating machine (without a guide plate), the vertical lower part of the paint is guided by the guide plate, so the curtain film is disturbed by the air current when the substrate is run at high speed. There is no.

It is the perspective view which looked at the curtain coating machine which concerns on embodiment of this invention from upper diagonally upper direction, Comprising: The right side part is shown with the cross section. It is a front view of the curtain coating machine which concerns on embodiment of this invention, Comprising: The state which is not flowing down the coating material and dilution liquid is shown. FIG. 3 is a side cross-sectional view taken along the line AA in FIG. 2 and shows a state in which a coating material and a diluent are flowing down. It is an expanded sectional view of the part which attached the guide plate of FIG.

Hereinafter, a curtain coating machine according to an embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a perspective view of a curtain coating machine 1 according to an embodiment of the present invention as viewed obliquely from above and shows a right side in section. 2 is a front view of the curtain coating machine 1, FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 4 is an enlarged cross-sectional view of a portion where the guide plate is attached in FIG. In addition, the top / bottom / left / right, the front / rear direction, and the width direction used in the following description refer to directions when the curtain coating machine 1 of FIG.

As shown in FIG. 1, the curtain coating machine 1 includes a curtain coating machine head 2 (hereinafter referred to as a head 2) that extends in the left-right direction (the width direction of the coated paper 60). As shown in FIGS. 1 and 3, the head 2 is provided with two chambers, a paint chamber 10 and a diluent chamber 20. These

chambers

10 and 20 have a semicircular cross section, and are provided continuously in the extending direction (left and right direction and width direction) of the head 2.

As shown in FIGS. 1 and 3, the paint chamber 10 is formed by assembling a paint-side main body 13 located on the front side and a triangular intermediate portion 14 with fixing bolts 15 (see FIGS. 1 and 2). Front and rear walls are configured. Similarly, the diluent chamber 20 is configured with front and rear wall portions by assembling the diluent side main body portion 23 and the intermediate portion 14 located on the back side with fixing bolts (not shown).

Further, side walls 5 are respectively provided on both sides of the paint chamber 10 and the diluent chamber 20 as shown in FIG. The side wall 5 is formed in a flat plate shape and closes the semicircular side portions of the

respective chambers

10 and 20. The side wall portion 5 is detachably attached to the paint side main body portion 13, the intermediate portion 14, and the diluent side main body portion 23 by fixing bolts 6. Thereby, each

chamber

10 and 20 comprises the sealed chamber. In addition, the side wall 5 is provided with supply pipes 3 and 4, which will be described in detail later, in a manner communicating with the

chambers

10 and 20.

The curtain coating machine 1 includes a supply tank (not shown) in which the paint 30 is stored, a defoaming machine (not shown) that removes bubbles in the paint 30, a circulation pump (not shown), and the like. Is provided. The paint chamber 10 is connected to these via the supply pipe 3 (see FIG. 2), and the paint 30 described above is supplied into the paint chamber 10.

Similarly, the curtain coating machine 1 is also provided with a supply tank (not shown) for supplying the diluent 40 to the diluent chamber 20. The diluent chamber 20 is connected to these via the supply pipe 4 (see FIG. 2), and the diluent 40 described above is supplied into the diluent chamber 20.

A nozzle 11 is formed on the lower side of the paint chamber 10. The nozzle 11 extends from the paint chamber 10 toward the rear obliquely lower side, and the paint 30 naturally flows down. The flow rate of the paint 30 that naturally flows down from the nozzle 11 is adjusted by the gap between the nozzles 11, and the curtain film 12 of the paint 30 that is uniform in the left-right direction of the head 2 is formed.

On the other hand, on the lower side of the diluent chamber 20, a nozzle 21 extending from the diluent chamber 20 toward the vertically lower side and allowing the diluent 40 to naturally flow down is formed. The flow rate of the diluent 40 that naturally flows down from the nozzle 21 is adjusted by the gap between the nozzles 21, and the curtain film 22 of the diluent 40 that is uniform in the left-right direction of the head 2 is formed.

The nozzle 11 extending from the paint chamber 10 and the nozzle 21 extending from the diluent chamber 20 are joined at their lower ends G as shown in FIGS. Therefore, the paint 30 and the diluting liquid 40 that flow down join each other at the lower end G. The coating material 30 and the dilution liquid 40 will be described later in detail, but will form two layers without being mixed with each other.

Further, a guide plate 24 is provided so as to extend below the diluent side main body portion 23 (a mode in which the diluent side main body portion 23 extends downward). The guide plate 24 is provided over the entire length of the head 2 in the left-right direction.

As shown in FIG. 4, the surface 24 c of the guide plate 24 is formed to be flush with the surface 22 c of the lip portion 22 in a state where the guide plate 24 is attached to the lip portion 22. As a result, the diluent 40 in the diluent chamber 20 flows downward while contacting the surface 22c at the lip 22 and, after flowing down from the lip 22, contacts the surface 24c of the guide plate 24. It will flow down without resistance.

Further, the lower side of the guide plate 24 extends to the vicinity of the coated paper 60 as shown in FIG. As a result, the guide plate 24 guides the diluent 40 to the vicinity of the coated paper 60, and the airflow generated when the coated paper 60 is fed in the B direction at high speed hits the

curtain films

12 and 22, and the curtain film. 12 and 22 are not disturbed.

Next, the effect | action of the curtain coating machine 1 which concerns on embodiment of this invention is demonstrated.
The coating material 30 stored in the coating chamber 10 and the diluent 40 stored in the diluent chamber 20 naturally flow down from the

nozzles

11 and 21 simultaneously with their own weight.

At this time, the diluent 40 contacts the surface 24c of the guide plate 24 and flows downward along the surface 24c to form the curtain film 22 of the diluent 40.
On the other hand, the coating material 30 contacts the surface 22c of the curtain film 22 of the diluent 40 and flows down along the surface 22c to form the curtain film 12 of the coating material 30.

That is, the curtain film 22 of the diluent 40 and the curtain film 12 of the coating material 30 flow down while constituting two layers without being mixed together.

Here, the above-described paint 30 is a paint generally used in the curtain coating machine 1 and has a viscosity as low as possible so that the curtain film 12 can be formed when it flows down. On the other hand, as the dilution liquid 40, for example, a dilution obtained by diluting the paint 40 with water or the like is used. Alternatively, it may be water or a surfactant solution. That is, as the dilution liquid 40, a liquid having a lower viscosity than the paint 30 is used. Therefore, the above-described coating material 30 flows down along the surface 22c of the low-viscosity diluent 40, and the coating material 30 has a higher viscosity than the diluent 40. Therefore, the coating material 30 is separated into two layers without mixing each other. It will flow down as it is.

In addition, since the diluent 40 has a low viscosity, the viscosity resistance is low when it comes into contact with the surface 24c of the guide plate 24 as compared with the paint 30. Therefore, in the absence of the diluent 40, when the coating material 30 and the surface 24c of the guide plate 24 come into contact with each other, the viscosity resistance increases, and the curtain film cannot be accelerated to an appropriate speed. Therefore, by interposing the diluent 40 between the surface 24c of the guide plate 24 and the coating material 30, the curtain end speed is appropriately controlled so that coating defects such as coating film skip do not occur.

Then, the coating material 30 and the diluent 40 flow down onto the coated paper 60 that travels at a high speed in a state where the two-layered structure is left and right, and a coating film surface is formed on the coated paper 60. The coated paper 60 after coating is dried in a drying process that is a subsequent process. At this time, as described above, since the diluent 40 is a solution obtained by thinning the paint 30 or water, only the paint 30 remains on the coated paper 60 after drying in the drying process. Therefore, the same quality as the case where it coats using only the coating material 30 is ensured on the coating surface.

According to the curtain coating machine 1 according to the embodiment of the present invention, the guide plate 24 that guides the diluted solution to the vicinity of the coated paper 60 while being in contact with the diluted solution 40 having a viscosity lower than that of the paint 30 is provided. Therefore, the curtain film 12 of the paint 30 can be formed on the opposite side of the dilution liquid 40 across the curtain film 22. Therefore, compared with the case where the coating material 30 is in direct contact with the guide plate 24, the curtain film 12 can be caused to flow down with a low viscous resistance. As a result, even if the paint 30 from the paint chamber 10 is flowed at a low flow rate, the curtain film 12 that is uniform in the width direction and has high stability can be formed.

Further, at the time of the conventional low flow rate, the paint 30 sometimes drops in the form of water droplets instead of the curtain film 12, but since the curtain film 12 can be formed at a low flow rate, the curtain can be formed. The coating flow rate can be reduced. Moreover, the coating film applied on the coated paper 60 can be thinned. In addition to this, the coated paper 60 can be coated at a higher speed as compared with the case of coating with a die coater.

That is, the reason why the die coater can be applied only at a low speed is that the termination speed of the paint film and the blowing speed are equal, so that acceleration due to free fall of the paint is not performed. For this reason, at a high speed, the stretch rate of the film becomes too large, the film cannot follow the stretch, and a phenomenon that the film is cut off occurs, resulting in a defect. On the other hand, since the conventional curtain system is accelerated by free fall, it is suitable for coating at a higher speed, but has a disadvantage that a curtain film cannot be formed with a low coating amount. The curtain coating machine 1 according to the embodiment of the present invention satisfies both of these merits.

Furthermore, in the conventional curtain coating machine, in order to prevent the curtain film from being disturbed by the traveling air current of the coated paper 60, an air cut device may be additionally provided in the vicinity of the curtain film. By providing, it is possible to prevent the curtain film 12 from being disturbed, so that it is not necessary to provide an air cut device.

Moreover, since the diluent chamber 40 is provided in the curtain coating machine head 2 to store the diluent 40 and flow downward, not only the paint 30 but also the diluent is provided in the head 10. 40 can also be stored and flowed down.

The curtain coating machine 1 according to the embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and various modifications and changes can be made based on the technical idea of the present invention. Is possible.

For example, in the present embodiment, it is described that the coating is performed on the coated paper 60 such as paper or cardboard, but the present invention is not limited to this. For example, the present invention can also be applied when a film is formed on a base material other than paper such as a plastic film.

In this embodiment, the head 10 is provided with one paint chamber 10 and one diluent chamber 20, but a plurality of them may be provided to cope with multicolor printing.

Furthermore, in the present embodiment, the diluent chamber 20 for storing the diluent 40 is provided inside the head 10, but may be configured separately from the head 10.

1 Curtain coating machine 2 Curtain coating machine head (head)
3, 4 Supply pipe 5 Side wall part 6 Fixing bolt 10 Paint chamber 11 Nozzle 12 Paint curtain film 13 Paint side main body part 14 Intermediate part 15 Fixing bolt 20 Diluent chamber (low viscosity liquid chamber)
21 Nozzle 22 Diluted liquid curtain film 23 Diluted liquid side main body 24 Guide plate 30 Paint 40 Diluted liquid (low viscosity liquid)
60 coated paper (base material)
G Lower end

Claims

The paint chamber is formed in a length along the width direction of the substrate to be coated, and extends in the width direction. In curtain coating machine equipped with a head for curtain coating machine that flows down the paint,
A curtain coating machine provided with a guide plate that guides the low-viscosity liquid to the vicinity of the substrate while in contact with the low-viscosity liquid having a viscosity lower than that of the paint.
The curtain coating machine according to claim 1, wherein a low-viscosity liquid chamber for storing the low-viscosity liquid and flowing it downward is provided inside the curtain coating machine head.
The curtain coating machine according to claim 1 or 2, wherein the low-viscosity liquid is a diluted liquid or water in which the paint is diluted.