JPH07256183A - Coating applicator - Google Patents

Abstract

PURPOSE:To prevent a coating liquid applied on a web from being splashed from the front surface of the web at the time of transporting the web. CONSTITUTION:An air floatation 8 for curving and guiding the web 1 in such a manner that the front surface side of the web comes to the inner side of an arc is installed in a position between a backing roll 2 and a guide roll 7 in the upstream side position thereof. A coating applicator 5 for applying the coating liquid 4 on the front surface of the web 1 is disposed between the air floatation 8 and the guide roll 7. A blade 6 is disposed in the position where the web 1 is run along the backing roll 2. The air floatation 8 has the arc- shaped front surface, has an air cell 10 on the inner side and has many air holes 9 on the front surface. The web 1 is floated and is so curved that the front surface side comes to the inner side by the air ejected out of the air holes 9 of the air floatation 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus used for producing a coated paper by applying a coating liquid on the surface of a web such as a base paper produced in a paper manufacturing factory.

[0002]

2. Description of the Related Art In many cases, base paper produced in a paper mill is processed paper as a product that meets a required purpose.
Among these processed papers, coated papers are manufactured by the operation of applying a coating liquid on the surface of the paper for the purpose of improving the properties of the surface of the paper. There is.

In a conventional coating apparatus, as shown in FIG. 4, a web 1 as a base paper is wound around a backing roll 2 along a lower surface side thereof, and the web 1 is backed by guide rolls 3 on an upstream side and a downstream side. 2 so as to be conveyed, and at a position below the backing roll 2,
A coating device 5 for coating the coating liquid 4 on the surface of the web 1 along the backing roll 2 is provided, and the coating liquid 4 coated on the surface of the web 1 is provided at a position downstream of the coating device 5. A blade 6 for scraping off the surplus portion to form a film of the coating liquid 4 having a required thickness on the surface of the web 1.
A structure in which is provided is generally adopted.

[0004]

However, the surface of the web 1 conveyed along the backing roll 2 is outside the arc of curvature of the backing roll 2, and the coating liquid 4 is applied to the web surface outside of this arc. In the conventional coating apparatus for coating the surface of the web 1 which is subjected to high speed coating (1000 m / min or more), centrifugal force is generated by increasing the peripheral speed of the backing roll 2 and increasing the speed. The coating liquid 4 applied by the coating device 5 may be splashed outward before reaching the blade 6 at the downstream side, resulting in a non-uniform coating state or a defect such as a pinhole. is there.

The centrifugal force generated by the rotation of the backing roll 2 is represented by F = K · v ² / r, where F: centrifugal force v: roll peripheral speed r: roll radius K: proportional constant.

Conventionally, an increase in the centrifugal force F was prevented by increasing the radius r of the backing roll 2, but this has not been a sufficient solution.

Therefore, the present invention is intended to prevent uneven coating by preventing the coating liquid from being spattered by centrifugal force when the web is conveyed.

[0008]

In order to solve the above-mentioned problems, the present invention applies a coating liquid to a web surface with a coating device and then scrapes off an excess of the coating liquid on the web surface with a scraping machine. Air that is connected to the air supply source on the inside of the arc so that the entire length corresponds to the width of the web and the surface has an arc surface with a required radius of curvature so that the surface side of the web is inside the arc until it falls. An air floatation, which has a chamber and has a large number of air holes formed in the arc surface, is installed on the front surface side of the web, and the web is conveyed along the non-contact state on the surface of the air floatation. The configuration is as described above.

Further, between a coating device for coating the web surface with the coating liquid and a scraping device provided facing the backing roll for scraping off the excess coating liquid applied on the web. The web may be linear.

The scraper may be a blade or a nip roll instead of the blade.

[0011]

When the air is ejected from the air holes on the surface of the air floatation, the web is curved and conveyed along the arc surface of the web without the surface contacting the air floatation. The coating liquid applied to the surface of the web will be pressed against the surface of the web by the centrifugal force when the web is passed through the surface of the airflotation. The adhesiveness to is increased.
Further, the coating material applied to the web is not blown off by the centrifugal force. As a result, the excessive amount of the coating liquid is scraped off by the scraping machine on the downstream side, so that a uniform coating thickness can be obtained.

When the web is linearly formed between the coating device and the scraping machine, since the curvature is zero, the coating liquid is prevented from being spattered by the centrifugal force when the web is conveyed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1A and 1B show an embodiment of the present invention, in which a plurality of guide rolls 3 for guiding the web 1 conveyed from the upstream side and a backing roll 2 are arranged. In the configuration that has been made, the backing roll 2 and
In order to bend the surface side of the web 1 between the guide roll 7 arranged at the upstream side position and the inside of the arc, the surface is formed into an arc surface having a required radius of curvature and the air chamber 10 is formed inside the arc surface. In addition, a large number of air holes 9 are formed on the surface of the arc surface
A semi-cylindrical air floatation 8 is installed, an air supply pipe 11 for supplying compressed air to the air chamber 10 of the air flowtion 8 is connected, and a large number of air holes on the surface of the air flowtion 8 are installed. By ejecting air from the web 9, the web 1 to be transported is transported along the surface of the air floatation 8 in a non-contact state. Further, a coating device 5 for coating the coating liquid 4 on the surface of the web 1 is installed between the guide roll 7 and the air floatation 8, and the surface side of the web 1 along the backing roll 2 is further installed. The blade 6 is positioned as a scraping machine at the position, and the surplus portion of the coating liquid 4 applied on the surface of the web is scraped off by the blade 6 so that a uniform coating thickness is obtained. Reference numeral 12 is a color pan for collecting the paint scraped off by the blade 6.

When the coating liquid 4 is applied to the surface of the web 1 by the coating device 5, the web 1 coated with the coating liquid is conveyed and is moved along the arcuate surface of the surface of the air floatation 8 to form the surface of the web 1. The sheet is conveyed while being bent with a required curvature so that the inside becomes inside. At this time, since high-pressure air is ejected from the large number of air holes 9 on the surface of the airflotation 8, the web 1 can pass through without contacting the airflotation 8. As a result, the coating liquid 4 applied to the surface of the web is not blown off by the centrifugal force as in the conventional case, but on the contrary, since the coated surface is directed toward the inside of the arc, the centrifugal force acts on the web. 1 receives a force in a direction such that it is pressed against the surface of the web 1, the adhesion to the web 1 is enhanced, and pinholes and the like can be prevented, and the permeability of the coating liquid 4 into the web 1 is also increased. Therefore, the coating amount can be increased and the coating amount can be increased.

FIG. 2 shows another embodiment of the present invention.
A nip roll 13 is arranged in place of the blade 6 as a scraping device in FIG. 1 (a), and the excess amount of the coating liquid 4 on the surface of the web 1 is scraped off by the nip roll 13 and other configurations. Is the same as that shown in FIG.

The embodiment shown in FIG. 2 can also achieve the same effects as those shown in FIG.

Next, FIG. 3 shows still another embodiment of the present invention, in which a guide roll 7 for guiding the web 1 linearly to the backing roll 2 is arranged at a position upstream of the backing roll 2. The coating liquid 4 is applied to the surface of the web 1 by the coating device 5 while being wound around the guide roll 7 and then linearly guided to the backing roll 2 at the position of the backing roll 2. The blade 6 serving as a scraping machine scrapes off the excess coating liquid 4.

In the embodiment shown in FIG. 3, since the web 1 is conveyed linearly between the portion where the coating liquid 4 is applied to the surface of the web 1 by the coating device 5 and the portion where the coating liquid 4 is scraped off by the blade 6, When the web 1 is conveyed, the coating liquid 4 is not blown off by centrifugal force, and it is carried to the position of the blade 6 in a state of being uniformly applied. Will not occur.

The air floatation 8 shown in the embodiments of FIGS. 1 and 2 may have slits provided in the direction perpendicular to the web instead of the air holes 9, for example.

[0021]

As described above, according to the coating apparatus of the present invention, from the time when the coating solution is applied to the web surface by the coating apparatus until the excess of the coating solution on the web surface is scraped off. An airflotion is formed on the front side of the web by forming the arcuate surface so that the surface of the web is on the inside of the arc and by forming a large number of air holes on the surface, and the web is contactless. Since it is conveyed along the surface of the web, (i) the centrifugal force when the web is conveyed does not cause the coating liquid to fly, and (ii) the centrifugal force when the web is conveyed. Since the coating liquid is urged in the direction of being pressed against the web surface, the higher the speed, the higher the adhesion between the web and the coating liquid, and the prevention of coating spots and pinholes. (Iii) Centrifugal force Reversely to keep the web and coating liquid The diameter of the backing roll can be made smaller compared to the conventional case where the diameter of the backing roll is made large to prevent the increase of centrifugal force, so that the cost can be reduced accordingly. Even if the web is conveyed linearly between the coating device and the scraping machine instead of the method using air flotation, it is possible to obtain excellent effects such as It is possible to obtain an excellent effect that coating unevenness, pinholes and the like on the web surface can be prevented without causing the coating liquid to fly off by centrifugal force.

[Brief description of drawings]

FIG. 1 shows an embodiment of a coating apparatus of the present invention,
(A) is a schematic side view, (B) is a perspective view of the air flow in (A).

FIG. 2 is a schematic side view showing another embodiment of the coating apparatus of the present invention.

FIG. 3 is a schematic side view showing still another embodiment of the coating apparatus of the present invention.

FIG. 4 is a schematic side view of a conventional coating apparatus.

[Explanation of symbols]

 1 Web 2 Backing Roll 3 Guide Roll 4 Coating Liquid 5 Coating Device 6 Blade (Scraping Machine) 7 Guide Roll 8 Air Flotation 9 Air Hole 10 Air Chamber 13 Nip Roll (Scraping Machine)

Claims (2)

[Claims] 1. The surface side of the web is inside the arc between the time when the coating liquid is applied to the web surface by a coating device and the time when the excess coating liquid on the web surface is scraped off by a scraping machine. , The entire length corresponds to the width dimension of the web and the surface is an arc surface having a required radius of curvature, and an air chamber connected to an air supply source is provided inside the arc surface, and a large number of air holes are formed in the arc surface. The coating apparatus is characterized in that the air floatation is formed on the surface side of the web, and the web is conveyed along the surface of the air flow in a non-contact state. 2. The web is applied between the time when the coating liquid is applied to the web surface by a coating device and the time when the excess amount of the coating liquid on the web surface is scraped off by a scraping machine provided facing the backing roll. It has a structure in which a web wound around a guide roll on the upstream side of the backing roll is linearly guided to the backing roll so as to be linear, and a coating device is arranged on the surface side of the web that is linearly conveyed. A coating device characterized in that