JPH11179276A - Drying method using non-contact web conveyor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the web drying method using a contactless web conveyor by which the curling of the selvage (side end in width direction) of the web is prevented only by setting the shape and capacity of a nozzle. SOLUTION: A gas blowoff nozzle 2 is alternately arranged above and below a web 1 in the traveling direction of the continuously conveyed web 1, the web is continuously waved and conveyed by this contactless web conveyor 5, and the coating soln. applied on the web 1 is dried. The nozzle 2 has a slit gas blowoff port 3 on both ends in the width direction of the web 1, the width of the blowoff port 3 is controlled to 3-10 mm, and the velocity of the gas blown from the port 3 is adjusted to 20-60 m/sec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drying a web coated with a coating solution using an apparatus capable of transporting the web in a non-contact manner.

[0002]

2. Description of the Related Art In general, as a method for transporting a web such as a plastic film or paper, an apparatus using a roller has been often used. However, in the case of conveyance by a roller, the roller and the web come into contact with each other, so that depending on the conveyance condition, scratches, wrinkles and the like may occur, and the web may be damaged.

Particularly, in a photographic light-sensitive material, generation of scratches and wrinkles on the light-sensitive surface (the surface coated with the emulsion layer) is fatal.
Therefore, in such a case, generally, a gas blowing nozzle is arranged so as to sandwich both sides of the web in the traveling direction of the web,
A drying method using a non-contact transport device that continuously floats and transports a web in a traveling direction by gas ejected from the gas blowing nozzle toward the web is often used.

However, when a web coated with a coating liquid on one or both sides is transported and dried, a phenomenon has occurred in which the web is curled as the coating liquid dries due to gas blowing. When such a curl is generated on the web, the web being transported flaps, and the web surface may be scratched, resulting in a defective product. In particular, when a photographic light-sensitive material is produced, when a silver halide emulsion layer using gelatin as a binder, a protective layer, or a backing layer is applied to a web having a thickness of 200 μm or less and dried, curling is likely to occur.

[0005] In a transfer method using a non-contact transfer device, a method for preventing curling of a web is disclosed in Japanese Unexamined Patent Publication No. Hei.
No. 123662 discloses that, in the vicinity of the inside of the concave portion of the curl at both ends of the web, the web is inclined in a direction perpendicular to the traveling direction of the web and perpendicularly or outwardly to the width direction of the web,
There is disclosed a non-contact web drying apparatus including an air nozzle for blowing curl correction air and an air supply device for supplying drying air or air under another condition to the air nozzle.

[0006] However, the above-mentioned prior art has a problem that the installation of an air nozzle is required separately, which complicates the apparatus and increases the equipment cost.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and uses only the form of the nozzle and the air flow rate to determine the edge of the web (the end in the width direction) at the time of conveyance. An object of the present invention is to provide a method for drying a web using a web non-contact transfer device capable of preventing curling.

[0008]

According to a first aspect of the present invention, a gas blowing nozzle is arranged alternately in the direction of travel of a continuously conveyed web so that the gas is blown in the direction of travel of the web. In a method of drying a coating liquid applied to a web using a web non-contact transfer device that floats and transfers in a continuous wave form, the nozzle is provided in the width direction of the web before and after in the transfer direction of the web. It has a slit-shaped gas outlet, the width of the gas outlet is 3 mm or more and 10 mm or less, and the wind velocity of the gas blown out from the slit-shaped gas outlet is 20 m / sec or more and 60 m or more.
/ Sec or less.

According to a second aspect of the present invention, in the drying method using the web non-contact transfer device according to the first aspect, the width of the gas outlet provided in the gas outlet nozzle is 4 mm or more and 6 m or more.
m or less.

According to a third aspect of the present invention, in the drying method using the web non-contact transfer device according to the first aspect, the air velocity of the gas blown from the gas blowout port provided in the gas blowout nozzle is 30 m / sec or more. It is characterized by being 50 m / sec or less.

According to a fourth aspect of the present invention, in the drying method using the web non-contact transport device according to the first, second or third aspect, the coating liquid is a coating liquid containing a hydrophilic polymer compound. Features.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is effective in a step of applying a silver halide emulsion layer, a protective layer, an undercoat layer or a back coat layer and drying the same when producing a photographic light-sensitive material. Usually, these coating liquids contain a hydrophilic polymer compound as a binder. As the hydrophilic polymer compound, gelatin is generally used, but in addition, albumin, proteins such as casein, hydroxyethyl cellulose, cellulose derivatives such as carboxymethyl cellulose, alginic acid, polysaccharides such as starch, polyvinyl alcohol, polyvinyl pyrrolidone, and poly A homopolymer or a copolymer such as acrylic acid and polyacrylamide is used. Hereinafter, an embodiment of a web drying method using a web non-contact transfer device according to the present invention will be described with reference to the drawings.

FIG. 1 shows a state in which the web 1 is conveyed in a non-contact manner while being dried by the web non-contact conveying device 5. The web 1 is a paper support having a coating liquid applied on one or both sides. Above and below the web 1, gas blowing nozzles 2 are arranged alternately with respect to the traveling direction of the web 1. A gas such as air is blown upward from a gas blowing nozzle 2 provided below the web 1, and a gas such as air is blown downward from a gas blowing nozzle 2 provided above the web 1. Thus, the web 1 is floated in a wave shape and transported in the direction of the arrow in the figure while maintaining the balance by the gas ejected from the upper and lower gas blowing nozzles 2.

The gas blowing nozzle 2 has a substantially rectangular parallelepiped shape as shown in FIG. The gas blowing nozzles 2 are provided with gas blowing slits 3 at both front and rear corners of the web 1 in the transport direction (the direction of the arrow in the figure). The gas blowing slit 3 is linearly provided in the width direction of the web 1 with a width of several millimeters. The gas blowing slit 3 is provided on the chamfered upper side of the corner of the gas blowing nozzle 2, and the air blown from the gas blowing slit 3 is blown upward. The web 1 is wound around a core (not shown), is given a certain tension, is floated by air blown from upper and lower gas blowing nozzles 2 and 2, and is conveyed.

As the air supplied to the gas blowing nozzle 2, dry air may be supplied by a fan, or may be supplied by a separately provided air compressor or the like.

A standard type of web non-contact transfer device generally used has a gas blowing nozzle with a slit width of 2 mm.
Those having a nozzle interval of 250 mm are often used.
A drying experiment was performed on the conventional web contactless transport device and the web contactless transport device according to the present invention under the following conditions to compare them.

In this comparative experiment, the support had a thickness of 10
A 0 μm paper coated on both sides with a polyethylene resin was used. With 10% gelatin solution as a coating solution, the coating amount of gelatin coating weight 8 g / m ^2, coating speed 150 meters /
Minutes.

The web non-contact transfer device according to the present invention is of a high air volume type and has a gas blowing nozzle having a slit width of 4 mm.
mm, and the nozzle interval was 500 mm.

As a non-contact web transfer device to be compared, a generally used standard type device having a gas discharge nozzle having a slit width of 2 mm and a nozzle interval of 250 mm was used.

The experiment was conducted at a stage where the gas velocity from the gas blowing nozzle was 20 m / sec and 30 m / sec, respectively. Table 1 shows the results.

[0021]

[Table 1]

From the above results, it is clear that the drying method using the web non-contact transfer device according to the present invention has a wind speed of 20 m / sec and a speed of 3 m / s.
No curling occurred on the web at both 0 m / sec.
Further, in the conventional drying method using the web non-contact transfer device, the web was curled at both the wind speeds of 20 m / sec and 30 m / sec.

As a result, in the drying method using the web non-contact transfer device according to the present invention, no curling occurred under any conditions.

As described above, according to the embodiment of the present invention, the slit width is increased and the wind pressure applied to the web is increased as compared with the conventional drying method using a web non-contact transfer device. At 20 m / sec or more, it became possible to prevent the occurrence of curl.

If only the prevention of curl generated on the web is considered, it is possible to reduce the curl generation rate by increasing the slit width. However, the larger the slit width, the more the same air volume can be obtained. Conflicting results such as reduced drying efficiency occur. In the present invention,
The slit width and the wind speed are limited as described above in order to prevent curl while minimizing a decrease in drying efficiency. That is, according to the present invention, it is undeniable that the drying efficiency is slightly reduced, but it is possible to prevent the curl from occurring on the web and improve the product yield.

The wind speed can be applied from 20 m / sec to 60 m / sec, preferably from 30 m / sec to 50 m / sec.
/ Sec. The slit width can be applied from 3 mm to 10 mm, but is preferably from 4 mm to 6 mm. The nozzle interval needs to be changed depending on how much the air volume is sent to the drying zone, and can be appropriately changed depending on the wind speed.

Further, the illustrated gas blowing nozzle 2 and the gas blowing port 3 are only examples, and are not limited to these shapes, and the design can be changed as appropriate. The web in the present invention is paper, plastic film,
Resin coated paper, synthetic paper and the like are included. further,
In the above-described embodiment, an example has been described in which only two gas blowing nozzles 2 are provided on the web transport path. However, the number is not particularly limited, and the design can be changed as needed.

[0028]

According to the first aspect of the present invention, the gas blowing nozzles are arranged alternately in the upper and lower directions in the traveling direction of the continuously transported web, and the web is transported while floating in a continuous wave shape in the traveling direction. In the drying method using the web non-contact transport device, the nozzle has a slit-shaped gas outlet provided in the width direction of the web before and after the web transport direction, and the width of the gas outlet is 3 mm or more. Since the wind speed of the gas blown from the slit-shaped gas blowout port is 20 mm / sec or more and 60 m / sec or less, it is possible to prevent the web from curling by using a nozzle having a simple structure. Thus, it is possible to provide a drying method using a non-contact transfer device which can reduce the cost.

According to the second aspect of the present invention, in the web drying method according to the first aspect, the width of the gas outlet provided in the gas outlet nozzle is set to 4 mm or more and 6 mm or less, so that the web drying method can be more effectively performed. The curl of the web can be prevented.

According to a third aspect of the present invention, in the method for drying a web according to the first aspect, the wind speed of the gas blown from the gas blowout port provided in the gas blowout nozzle is set to 30 m.
By setting the speed to not less than / m and not more than 50 m / sec, it is possible to more effectively prevent the curl of the web.

According to the invention described in claim 4, claim 1,
In the method for drying a web according to claim 1 or 2, the curling of the web can be prevented even if the coating liquid is a coating liquid containing a hydrophilic polymer compound.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a web non-contact transfer device to which the present invention can be applied.

FIG. 2 is a perspective view showing an example of a nozzle that can be used in the web non-contact transfer device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Web 2 Gas blowing nozzle 3 Gas blowing port 5 Web non-contact transfer device

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI D21H 19/12 D21H 1/06 F26B 13/20 1/38

Claims (5)

[Claims] 1. A web non-contact transfer device in which gas blowing nozzles are arranged alternately in the upper and lower directions of the direction of travel of a continuously conveyed web, and float and convey the web in a continuous wave direction. In the method of drying the coating liquid applied to the above, the nozzle has a slit-shaped gas outlet provided in the width direction of the web before and after in the transport direction of the web, and the width of the gas outlet is 3 mm or more. 10 mm or less, and
A drying method using a web non-contact transfer device, wherein the air velocity of the gas blown from the slit-shaped gas blowing port is set to 20 m / sec or more and 60 m / sec or less. 2. The drying method according to claim 1, wherein the width of the gas outlet provided in the gas blowing nozzle is 4 mm or more and 6 mm or less. 3. The air velocity of a gas blown from a gas outlet provided in the gas blowing nozzle is 30 m / sec or more.
The drying method according to claim 1, wherein the drying speed is not more than m / sec. 4. The coating liquid according to claim 1, wherein the coating liquid is a coating liquid containing a hydrophilic polymer compound.
A drying method using the web non-contact transfer device according to 1. 5. The drying method according to claim 1, wherein the web is a support in which both sides of a paper are coated with a polyethylene resin.