JPH06246215A - Bladeless coater - Google Patents

Abstract

PURPOSE:To provide a coater with an inexpensive running cost which can feed stably a uniform coating liq. film on the surface of a web. CONSTITUTION:A coating liq. extrusion slit main body is constituted by arranging a slit lip facing to a web being wound and carried by means of a backup roll 12 and an air ejecting nozzle main body 4 for eliminating air accompanied with the web is arranged on the upstream side in the carrying direction of the web. Faces of both a coating liq. extrusion slit main body and the air ejecting nozzle main body 4 facing each other are processed into a shape so as to joint tightly together and an adjusting bolt 9 adjusting freely the gap of both parts and an actuator 6 are provided to form an air introducing flow path 18. Air flow accompanied with the web is eliminated with the air ejected from the air ejecting hole 5 and unstabilization and breakage of a coating liq. film caused by decrease in pressure from the ejection position of the air ejecting flow to the position where the extruded liq. 10 extruded from the slit nozzle is transferred on the web, is prevented from generating by the introduced air from the air flow path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coater in an iron making process, a paper making machine, a non-woven fabric coating apparatus, etc.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional coating apparatus (blade coater, post-metering type).

In the figure, a coating liquid 10 discharged from a slit nozzle 15 is transferred onto the surface of a web 11 which is wound around a backup roll 12 and conveyed.

The thickness of the transfer film 13 of the coating liquid formed on the web 11 is the scraping blade 16 for mixing air entrained by the web during transfer of the coating liquid and for measuring the coating amount and finishing the surface. In order to avoid the occurrence of coating failures such as scratches (defective coating) below, the thickness is 10 to 20 times the thickness of the coating film 14 on the web after the coating amount is measured.

A transfer coating liquid film 13 on such a web 11
The excess coating liquid 20 is scraped off by the measuring / finishing scraping blade 16 supported by the blade holder 17 provided downstream of the web 11 transfer direction, and at the same time, the coating film surface is finished smooth.

At this time, the control of the coating liquid film thickness or the coating liquid amount on the web 11 on the downstream side of the scraping blade 16 is performed by controlling the force pressing the scraping blade 16 against the web 11 and the transfer liquid film 13. It is done by controlling.

When the web 11 is permeable to paper, non-woven fabric, etc., the coating liquid permeates into the web 11 by the fluid pressure of the coating liquid generated under the blade 16.

[0008]

By the way, in the conventional method as described above, when solid matters such as pigment particles are present in the coating liquid, the tip of the scraping blade 16 is abraded over time. .

Therefore, it is necessary to adjust the pressing force of the scraping blade 16 against the web 11 and the transfer liquid film 13 and to perform maintenance such as replacement of the scraping blade 16 every time the operation is performed for a certain period of time.

The excess transfer liquid scraped off by the scraping blade 16 is recovered, recirculated and transferred again onto the web 11. During this time, the coating liquid is removed from the web 11 and transferred.
In some cases, the physical properties of the coating liquid may change due to the migration of water, changes in the concentration of volatile components, inclusion of foreign matter, inclusion of air bubbles, and the like.

Each of the problems described above occurs because a method is used in which the coating liquid is excessively transferred onto the web and the excess is scraped off.

The present invention solves the above-mentioned problems, eliminates the need to transfer the excess coating liquid, and further eliminates the transfer of the excess coating liquid to the web. Therefore, the scraping blade can be omitted. It is intended to provide a bladeless coater.

[0013]

As a structure for achieving the above object, a bladeless coater of the present invention is provided with a slit nozzle for discharging a coating liquid, which is arranged so as to face a web to be transferred, and a nozzle for the same. An air nozzle disposed on the upstream side for ejecting air toward the upstream of the web surface, a coating liquid film ejected from the slit nozzle, and a space defined by jet air ejected from the air nozzle. It is characterized by having an air introduction flow path for introducing air.

[0014]

According to the present invention, the entrained air flow on the surface of the web, which is the largest cause of the surplus coating liquid having to be transferred once onto the web as in the prior art described above, is Excessive transfer of the coating liquid is eliminated by eliminating the excess coating liquid by an air jet ejected from an air jet nozzle arranged on the upstream side of the web transfer position in the web transfer direction so as to face the air entrained with the web.

Further, the air pressure from the jet of the air jet until the coating liquid is transferred to the web is excessively lower than the atmospheric pressure, and the free surface of the coating liquid film discharged from the slit nozzle is upstream in the transfer direction. In order to prevent the liquid film from being destroyed or unstable due to the force that pulls it toward the side, in the web width direction from the position where the air jet is jetted to the position where the coating liquid is transferred onto the web. The air pressure in this region is adjusted by providing an air flow path that can uniformly introduce air.

With these, a predetermined coating liquid film can be uniformly coated on the web without the inclusion of air bubbles. Further, since it is not necessary to transfer the web of the excess coating liquid, the scraping blade is not necessary.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. This embodiment is for paper coating, and shows an example in which a coating liquid discharge slit main body and an air jet nozzle main body for web entrained air removal arranged upstream in the web transfer direction are divided.

The present invention can be similarly applied to iron making and other processes.

In FIG. 1, 1 is a backup roll 1.
The slit lips on the downstream side in the web transfer direction, which are arranged so as to face the web 11 wound around the web 2 and transferred, 2 are slit lips arranged on the upstream side in the web transfer direction of the lip 1, which are holders. It is supported by the block 3 and constitutes the coating liquid discharge slit body.

On the upstream side of the discharge slit body in the web transfer direction (the right side portion in FIG. 1), an air jet nozzle body 4 for removing entrained air from the web is arranged in a divided state.

In the case of this embodiment, the tip of the lip 2 on the upstream side in the web transfer direction of the coating liquid discharge slit body is formed so as to be parallel to the surface of the web 11 about 0.1 to 30 times the gap of the liquid discharge slit. ing.

The length of the parallel surface of the tip of the lip 2 to the web (0.1 to 30 times the slit gap) is determined by the slit clearance to be formed, the coating liquid surface tension, the viscosity, the coating liquid film flow velocity and in this region. This value is considered to be preferable for stabilizing the liquid film formed on the object to be coated, considering the atmospheric pressure and considering the contracted state of air that occurs under the actual nozzle arrangement conditions.

Further, the facing surfaces of the coating liquid discharge slit body (lip 2 in this embodiment) and the air jet jet nozzle body 4 are processed into a shape such that they are in close contact with each other, and the distance between the two bodies is small. An adjusting bolt 9 and an actuator 6 are fixedly arranged on the upper surface portions of both of them so that they can be arbitrarily adjusted.

When the discharge liquid film 10 discharged from between the slit lips 1 and 2 is unstable or destroyed by the entrained air removing air jet, the coating liquid is adjusted by the space adjusting mechanism including the actuator 6 and the space adjusting bolt 9 described above. The discharge slit main body and the air jet jet nozzle main body 4 are separated from each other, and the outside air is introduced from the gap created thereby, that is, the air introduction flow path 18 to stabilize the coating liquid film 14 on the web 11.

Reference numeral 5 denotes a rotatable air jet outlet arranged at the tip of the air jet nozzle main body 4, and the opening direction of the jet outlet is located upstream of the web transfer direction (rightward in FIG. 1). There is. Reference numeral 8 is an air jet adjusting valve.

The web entrained air flow developed on the web 11 wound around the backup roll 12 and transferred is generated by the air jet ejected from the ejection port 5 at the tip of the counter air jet nozzle body 4 for entrained air removal. Web 1
1 It is peeled from the surface.

Further, since the air jet is jetted upstream in the web transfer direction, the air in the area from the air jet outlet 5 until the discharge liquid film 10 is transferred onto the surface of the web 11 is the air jet. Due to the entrainment action, there is a tendency to flow upstream in the web transfer direction, and as a result, the air pressure in this region tends to be lower than atmospheric pressure.

The discharge liquid film 10 discharged from the coating liquid discharge slit is the upstream side in the web transfer direction due to the difference in air pressure between the upstream side and the downstream side (atmospheric pressure) in the web transfer direction with the liquid film 10 interposed therebetween. It shows a tendency to bend.

In order to prevent the liquid film 10 from being broken (film breakage) and the occurrence of unstable flow when the liquid film 10 is bent as described above, the lips 1 and 2 forming the coating liquid discharge slits. Among these, a flat portion is formed so that the tip of the upstream lip 2 in the web transfer direction is parallel to the surface of the web 11 by 0.1 to 30 times the gap of the liquid discharge slit.

The air introducing passage 18 controlled by the interval adjusting mechanism allows uniform introduction of air in the web width direction from the air jet ejection position to the position where the coating liquid is transferred onto the web 11. The pressure in this area is adjusted by this.

The arrangement position of the coating apparatus and the discharging direction of the coating solution are not particularly limited around the backup roll.

Next, FIG. 2 shows an embodiment in which the present invention is combined with the conventional coating method shown in FIG. The same parts as those in FIGS. 1 and 3 are designated by the same reference numerals, and detailed description thereof will be omitted. In addition, 19 is a weir.

When such a method is adopted, a conventional blade coater is used in the first-stage coating section to utilize the high fluid pressure generated under the blade to apply the coating solution 10 to the web 11
It is possible to easily apply the apparatus of the embodiment of the present invention as the second stage coating section (surface layer coating) without permeating the inside and drying the coating liquid film.

At this time, since the second-step coating portion is completely out of contact with the surface of the first-step coating layer, the web of the second-step coating portion is not so contacted as compared with the case of using the conventional technique for the second-step coating portion. Problems such as wrinkling due to swelling and mixing of the first-stage coating liquid into the second-stage scraping surplus liquid can be solved, and handling becomes extremely easy.
At the same time, space and energy costs can be reduced.

As a typical example of the coating liquid described in each of the above-mentioned examples, when it is used for coated paper, 100 (pigment such as clay and calcium carbonate) to binder (SB latex, starch, CMC, etc.) 18 parts, 0.5 parts by weight of a dispersant, etc. as a main component into a slurry of 58 to 65% by weight, for a general A2 class coating liquid, and in the case of colored steel sheets, the heating residue is 60 to 80% by weight. Examples include organic paints.

Although the embodiments of the present invention have been briefly described above, the present invention is not limited to the above embodiments, and various design changes can be made within the scope of the technical idea of the present invention. It belongs to the technical scope of the invention.

[0037]

As described above, the bladeless coater of the present invention has the following effects. (1) A uniform coating liquid can be stably supplied onto the web surface.

(2) The web is not in contact with the coating device,
Unlike conventional scraping blades, there are no parts that require replacement or maintenance, and running costs are low.

(3) Since the excess coating liquid is not recirculated, the liquid is not deteriorated and the yield is good.

(4) It is relatively easy to implement.

[Brief description of drawings]

FIG. 1 is a sectional view of a bladeless coater according to an embodiment of the present invention.

FIG. 2 is a wet multi-layer coating diagram in which the apparatus of one embodiment of the present invention and the conventional apparatus are combined.

FIG. 3 is an operation explanatory view showing an example of a conventional blade coater.

[Explanation of symbols]

 1 Downstream slit lip 2 Upstream slit lip 3 Holder block 4 Air jet nozzle body 5 Air jet nozzle 6 Actuator 8 Air jet adjusting valve 9 Spacing adjusting bolt 10 Discharge liquid film 11 Web 12 Backup roll 14 Coating liquid film 16 Scratch Removal blade 17 Blade holder 18 Air introduction passageway 19 Weir plate 20 Excess coating liquid

Claims (1)

[Claims] 1. A slit nozzle for discharging a coating liquid, which is arranged to face a web to be transferred, and an air nozzle which is arranged on the upstream side of the nozzle and jets air toward the upstream side of the web surface. A bladeless coater comprising an air introduction flow path for introducing air into a space defined by a coating liquid film discharged from the slit nozzle and jet air ejected from the air nozzle.