JPH06277616A - Method for coating - Google Patents

Abstract

PURPOSE:To provide a method for coating wherein an effective width of a coating liq. can be obtd. and there exists no possibility of inferior drying caused by liq. standing on the edges of a resin in a method for coating wherein the coating liq. is excessively fed on an edge seal supporting body and it is adjusted to a specified amt. of coating by means of a metering bar. CONSTITUTION:After a coating liq. is excessively fed on a continuously running web 5, the coating liq. on the web 5 is sucked and removed by means of a nozzle 1 set just before a metering bar 2 and on the coated side. It is possible thereby to provide stably a part where the coating liq. is substantially uncoated on the edge part of the web and to prevent staining of a paper roll after a dryer and trouble of blocking after winding caused by inferior drying due to liq. standing from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous long belt-shaped flexible support (hereinafter abbreviated as "web") in the production of photographic film, photographic paper and other photographic light-sensitive materials.
In particular, the present invention relates to a method for applying a coating liquid, and more specifically, to a coating method for providing a portion on the edge of the web where the coating liquid is not substantially applied.

[0002]

2. Description of the Related Art Conventionally, as a photographic support (hereinafter abbreviated as "support"), so-called baryta paper has been used in which a baryta layer mainly containing barium sulfate is coated on one side of paper. In order to automate and speed up the developing process, waterproof photographic printing paper coated with hydrophobic polyolefin resin on both sides of the stencil has come to be used, and nowadays it occupies most of the support.

Conventionally, a support coated with a hydrophobic polyolefin resin has been provided for a photographic emulsion coating step after laminating the base paper with the polyolefin resin and slitting the base paper into a predetermined product width. However, in recent years, the edge of the base paper is used as the base paper in the polyolefin resin laminating process in order to prevent contamination with paper powder in the photographic emulsion coating process and to reduce and reuse the waste in the slit parts in the support manufacturing process. It is possible to manufacture a support (hereinafter abbreviated as "shield edge base") that is coated from both sides of the base material, slits only the polyolefin layer, and seals the edges of the base paper with the front and back polyolefin layers. Has come to be demanded from both sides.

A photographic printing paper using a support coated with a hydrophobic polyolefin resin (hereinafter abbreviated as "printing paper") usually has a curl property on the surface opposite to the surface coated with a photosensitive layer. A back coat layer is usually provided for the purpose of improvement, imparting antistatic properties, and the like. This backcoat layer is usually applied in a high concentration and in a thin layer in order to improve productivity by high-speed processing, and various coating methods are known, one of which is an excessive coating solution. After feeding to the web, there is a method in which a metering bar such as a wire bar measures the coating amount to a predetermined amount.

In the coating step of this coating method, the width of the coating liquid after being measured on the web is wider than the width of the coating liquid supplied to the web due to the action of the metering means by the metalling bar and the surface tension of the coating liquid. . In addition, when the tension in the width direction of the web when measuring the coating liquid is not uniform and the tension of the edge portion is low, the edge portion is partially thickly coated, and in the subsequent drying step, poor drying of the thickly coated portion occurs. Therefore, excessive drying conditions must be set as a whole, leading to a reduction in energy efficiency.

In particular, as a measure against the above-mentioned paper dust, in the shield edge base in which the edges of the base paper are completely covered with the resin that covers the front and back sides of the base paper, a portion formed only by the polyolefin resin layer at the edge (hereinafter referred to as "resin ear"). Is, of course, thinner than the part containing the base paper, has low rigidity, and is not stiff.Therefore, after measuring the coating liquid with the metalling bar, excess coating liquid adheres to the resin ears. In addition, the resin ears corresponding to the edges of the base paper are likely to collect liquid, and the rolls after the dryer are contaminated due to poor drying of this part, and blocking after winding has occurred.

As a method of removing the thick coating on the edge,
As described in U.S. Pat. No. 2,899,339, a diluting liquid or a jet stream of a solvent or a spray liquid is supplied from the outer peripheral portion of the L-shaped tube having a double structure, and suction is performed together with the coating liquid from the central portion. The method of removal has been reported. Further, Japanese Patent Laid-Open No. 56-73579 and Japanese Utility Model Laid-Open No. 60-49949 describe a method of sucking and removing a thick coating portion by almost the same method. However, in these methods, when the position of the suction nozzle is outside the position of the edge of the web, the coating liquid wraps around to the opposite side of the coating surface and contaminates the backup roll, thereby deteriorating the quality of the product. Will end up. Further, it is impossible to completely eliminate the liquid pool in the resin edge portion corresponding to the edge portion of the base paper by these methods.

[0008] As a method of eliminating the thick coating portion, the actual construction of Sho 63-
Japanese Patent No. 136765 discloses a processing device having a function of cleaning a backup roll. However, when it is applied to the shield edge base, it is unavoidable that the cleaning liquid accumulates in the resin edge part corresponding to the edge of the base paper, which also causes poor drying of the edge part and contaminates the paper roll after the dryer. Become.

Further, the width of the coating liquid obtained after being measured by the metering bar is determined by the support in order to prevent thick coating on the resin ears without removing a part of the coating liquid on the web. It is conceivable to control the width of the coating liquid supplied to the web so that the width becomes less than or equal to However, in this method, the coating width varies depending on the amount of the coating liquid supplied to the web and the like, and in many cases a stable predetermined coating width cannot be obtained, resulting in lack of operational stability.

[0010]

The present invention is effective in a coating method in which a coating liquid is excessively supplied onto a shield edge strip-shaped flexible support and then a predetermined coating amount is adjusted by a metering bar. An object of the present invention is to provide a coating method in which the width of the coating liquid can be obtained and a portion which is not coated on the resin ear portion can be left uncoated stably.

[0011]

According to the present invention, after excessively supplying the coating liquid to a shield edge strip-shaped flexible support that continuously runs, the coating liquid on the support is fixed by a metaling bar.
In a coating method for measuring to a predetermined coating amount, in order to stably provide a portion where the coating liquid is not substantially coated on the edge of the support, a nozzle provided immediately before the metering bar on the coated side is used to remove excess It is achieved by sucking and removing the coating liquid.

The details of the present invention will be described below.
FIG. 1 is a side view showing an example of a metalling unit according to the configuration of the present invention. The coating liquid suction nozzle 1 installed adjacently on the upstream side of the metalling bar 2 in the web running direction sucks and removes the coating liquid at the edge of the web. The coating liquid suction nozzle in the present invention may have a double pipe structure which has been conventionally used, but in order to suck and remove the coating liquid efficiently, the tip diameter is 1.0 to 5. 0m
A nozzle of about m is preferable. If the suction nozzle is smaller than 1 mm, foreign matter is apt to be clogged in the nozzle, and the unpainted portion is liable to be variable due to a reduction in suction efficiency. Further, when the nozzle diameter exceeds 5 mm, the suction pressure tends to become unstable, and the uncoated width becomes uneven due to pressure fluctuation, and when it becomes poor, coating unevenness occurs. The nozzle opening may be slit-shaped or circular.

The position of the nozzle may be adjusted so that it does not come into contact with the surface of the web.
A position of about 5 to 2.0 mm is preferable. If the width is less than 0.5 mm, the fluctuation of the continuously running shield edge strip-shaped flexible support becomes large to some extent. For example, in the case of water-resistant polyolefin resin-coated paper, as a result of the nozzle scraping the support, polyolefin lees are generated. , It adheres to the nozzle as foreign matter, significantly reduces the suction ability, and there is no uncoated portion.In the worst case, the liquid flows to the opposite side of the coated surface of the support, thick coating portion occurs, paper after dryer Not only does this cause contamination of the rolls, significantly lowering the quality, but it also reduces the productivity due to the cleaning work of the paper rolls.

FIG. 2 is a front view showing the installation position of the suction nozzle in the present invention. The nozzle 1 is installed immediately in front of the metering bar 2 along the line traveling direction. In addition, the nozzle 1 extends from the end of the paper base to the width direction of the continuously running shield edge strip-shaped flexible support, that is, in the direction perpendicular to the line running direction, with the edge portion of the paper base of the web as a base point. It is preferable to install it within a range of 10 mm inside. Particularly, the preferable nozzle installation position is in the range of 0 to 5 mm from the end of the paper substrate. If the nozzle is installed on the base paper base side more than 10 mm from the paper base end, the unpainted area becomes large and it becomes uneconomical.
The coating liquid may be supplied from the end of the paper substrate to the resin ear side due to fluctuations in the shield edge strip-shaped flexible support that continuously runs, and the coating liquid accumulates in the resin ear portion, causing poor drying, and after the dryer. Will contaminate the paper roll. Also, if the nozzle is installed from the end of the paper base to the resin ear, the resin ear is thinner than the paper base, has low rigidity, and is not stiff, so it is not possible to remove the excess coating liquid with the metalling bar. In addition, liquid liquor is liable to be generated in the resin edge portion, which causes contamination of the paper roll after the dryer due to poor drying of this portion and blocking failure after winding.

In order to more effectively carry out the coating method of the present invention, when the coating solution is excessively supplied to the web, the coating width is made narrower than the width of the web so that the coating solution does not adhere to the resin ears. Preferably. In the present invention, as a method of supplying the coating liquid to the web, an existing coating device such as a gravure roll system, a roll coating system, a slide hopper system, a die system can be used. As the metalling system, a system in which tension is applied to the metalling bar as shown in FIG. 1 or a rod coater system in which a coating rod is pressed against a web supported by a backup roll can be adopted. Further, as the metalling bar, either a plain coating rod or a wire bar wound with a wire can be used.

The web in the present invention includes all kinds of webs such as plastic film, metal foil, synthetic paper and coated paper in addition to the above-mentioned hydrophobic polyolefin resin coated paper. As the polyolefin resin for the hydrophobic polyolefin resin-coated paper, two or more kinds of homopolymers such as low-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, polybutene and polypentene, or ethylene-propylene copolymer can be used. Copolymers of olefins and mixtures thereof can be used. In this hydrophobic polyolefin resin,
White pigments such as titanium oxide, zinc oxide, talc, calcium carbonate, stearic acid amide, fatty acid amides such as arachidic acid amide, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zirconium stearate, sodium palmitate, Fatty acid metal salts such as calcium palmitate and sodium laurate, tetrakis (methylene-3
(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) methane, 2,6-di-tert
-Antioxidants such as butyl-4-methylphenol, blue pigments and dyes such as cobalt blue, ultramarine blue, cerulean blue and phthalocyanine blue, magenta pigments and dyes such as cobalt violet, fast violet and manganese violet, bis (tert-butyl) Benzoxazole) thiophene, bis (methylbenzoxazole) naphthalene and other optical brighteners, UV absorbers such as Tinubin 320, Tinuvin 326, Tinuvin 328 manufactured by Ciba-Geigy can do.

As the plastic film, polyolefin (eg polyethylene, polypropylene), polystyrene, polyvinyl chloride, polyacrylic acid ester,
Homopolymers or copolymers of linear polyesters (eg polyethylene terephthalate), polycarbonates, polyamides (eg nylon), cellulose acetates (eg cellulose triacetate), polyacrylonitrile and the like, and mixtures thereof can be used.

The coating solution used in the present invention is gelatin, polyvinylpyrrolidone, polyvinyl alcohol, sodium polystyrene sulfonate, styrene-maleic anhydride copolymer, styrene-acrylic acid ester-methacrylic acid copolymer, sulfate ester compound of polysaccharide. Aqueous solution of hydrophilic polymer compound such as, cellulose ester, polyvinyl acetal, polyvinyl chloride, polyvinylidene chloride, polystyrene, acrylic resin, an organic solvent solution of a phenol resin as a binder solution, if necessary, a surfactant, a pigment, Additives such as dyes and effect agents can be included.

The coating amount of the coating liquid in the present invention is not particularly limited, but in order to efficiently suck and remove the coating liquid, it is 1 to 200 g / m ² at the time of supplying to the web, and 0.1 after being weighed. It is preferably about 80 to 80 g / m ² .

[0020]

[Operation] After the coating liquid is excessively supplied to the shield edge strip-shaped flexible support that continuously runs, the metaling bar
When a nozzle is installed on the opposite side of the coated surface to suck and remove excess coating liquid, the resin ears are thinner than the paper substrate and have low rigidity and no stiffness, so with a metaling bar Excessive coating liquid cannot be removed, and liquid pooling easily occurs between the resin edge and the end of the paper substrate. Cause blocking failures. For this reason, in order to prevent the occurrence of liquid pool, the nozzle provided immediately before the metaling bar on the coated surface side sucks and removes the excess coating liquid, and the coating liquid is substantially coated on the edge of the support. By providing a stable part, the paper roll contamination after the dryer due to poor drying,
Blocking failure after winding can be prevented.

[0021]

EXAMPLES The present invention will be described below in detail with reference to specific examples, but it goes without saying that the present invention is not limited to these examples. (Examples 1 to 4 and Comparative Example 1) A gravure method is used as a device for supplying a coating liquid to a web, and a coating amount is measured with a wire bar. Shield edge polyethylene coated paper with gelatin as binder, solid content 1
A coating solution of 0%, a viscosity of 10 cps, and a surface tension of 30 dyne / cm was supplied at a coating speed of 150 m / min by a gravure roll with a coating width shown in Table 1 at 10 g / m ^2, and the coating amount was 2 g / m with a plane bar. ^It was applied so as to be ² . At that time, application was performed by providing a suction nozzle inward from the end of the resin ear as shown in FIGS.
The results are shown in Table 1.

(Comparative Examples 2 to 4) Under the same conditions as in Examples,
As shown in FIGS. 3 and 4, the suction nozzle was installed by installing the nozzle on the side opposite to the surface coated with the coating liquid. The results are also shown in Table 1.

[0023]

[Table 1]

[0024]

According to the present invention, an effective coating liquid width can be obtained in the coating method in which the coating liquid is excessively supplied onto the shield edge support and then the coating amount is adjusted to a predetermined coating amount with a bar. Moreover, it is possible to provide a coating method that does not cause thick coating on the resin ear portion.

[0025]

[Brief description of drawings]

FIG. 1 is a side view of a metalling portion showing an example of an embodiment of the present invention.

FIG. 2 is a front view schematically showing an installation position of a suction nozzle according to the present invention.

FIG. 3 is a side view of a metalling portion showing an example of a comparative example, in which a nozzle is provided on the opposite side of the metabar.

FIG. 4 is a front view showing an installation position in a width direction of a support body of a suction nozzle, which is an example of a comparative example, and the nozzle is right above a resin ear.

[Explanation of symbols]

1 Coating Liquid Suction Nozzle 2 Metalling Bar 3 Metalling Bar Support 4 Coating Liquid Suction Tube 5 Web 6 Coating Liquid 7 Shield Edge Polyolefin Resin Coated Paper Resin Ear Part 8 Shield Edge Polyolefin Resin Coated Paper Paper Base Terminal Part 9 Coating Station liquid suction opening

Claims (1)

[Claims] 1. A coating method in which a coating liquid is excessively supplied to a continuously running shield edge strip-shaped flexible support, and then the coating liquid on the support is metered to a predetermined coating amount by a metering bar. The coating is characterized by sucking and removing the excess coating liquid with a nozzle provided immediately before the metering bar on the coated side in order to provide a portion where the coating liquid is not substantially coated on the edge of the support. Method.