JPS5888074A - Continuous coating method of web with joint part - Google Patents

Abstract

PURPOSE:To enable to perform excellent continuous coating work without the need to pretreat a joint part, by drawing a coating head apart from the surface of a web to a certain degree such that an applying liquid does not become disjoint from the surface when the joint part between the webs is passing through coating beads, and returning the coating head when the joint part has passed. CONSTITUTION:In applying the beads of an applying liquid 4 to running webs 3, 3 with a joint part 5, a coating head 2 is shifted to such a degree that the applying liquid 4 does not become disjoined from the surfaces of the webs, e.g. about 500-2,500mum, along a direction opposite to a coating roll 1 when the joint part 5 between the webs is passing through the coating beads. When the joint part 5 has passed, the coating head 2 is rapidly returned to its original position. Consequently, splashes of bubbles, uneven application of paint, disturbance in the layer of the applying liquid, etc. can be effectively eliminated without the need to pretreat the joint part between the webs.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of applying a coating liquid to a running web,
In particular, the present invention relates to a method of continuously applying a coating liquid to a web having joints using the B-P coating method.

In the photographic industry, photographic materials such as photographic film and photographic paper are produced by coating various materials including silver halide emulsions on long strip-shaped supports (hereinafter referred to as webs) such as polyethylene terephthalate film, Nonolighter paper, or double-sided polyethylene coated paper. Manufactured by applying one or more layers of photographic coating fluid. The manufacture of these photographic materials is usually continuous coating to increase production efficiency and reduce costs. However, the length of the web that serves as a support for photographic materials is generally limited, and it is common practice to make the web into a long length using a joining tape or the like for continuous coating.

When joining webs using a joining tape, the trailing end of one web is usually butted against the leading end of the other web, and one or both sides of the web are joined using the joining tape. So-called butt joining is often performed, and when joining only one side with a joining tape, it is advantageous for the coating to apply the joining tape to the side to which the coating liquid is applied.

However, when a coating liquid is continuously applied to a nib having such a joint, various problems occur. 1st
The figure shows the coating situation using the Sly P hopper type bead coating device! However, the distance α between the web surface where coating bead R is formed and the tip of hotlet A is usually 80
When the joint part of the web passes through the coating bead forming part, for example, if the joining tape is attached only to the surface of the web, the web surface will instantly change as shown in Figure 2. The distance between the bonding tape surface (in this case) and the tip of the hopper becomes narrower by the thickness of the tape, and the coating thickness of the coating liquid becomes irregular.Also, when two or more layers of coating liquid are coated simultaneously, In addition, when the joint passes through the joint, the adhesive and dirt adhering to the joint tape, as well as the generation of bubbles due to the inclusion of air, cause the web surface to be coated with the coating liquid to be vertically damaged. There is a drawback that streak-like uneven coating occurs over a considerable length.

These webs with coating defects have no commercial value and are disposed of, but as the amount of discarded webs increases, productivity decreases and manufacturing costs increase. .

In Figures 1 and 2, 1 is a coating roll, 2
13 is a web running in the direction of the arrow, 4 is a coating liquid, and 5 is a joining tape.

As a method of improving the above-mentioned defects when passing through the joint, it is proposed to apply some treatments to the joint of the web in advance, as disclosed in, for example, Japanese Patent Publication No. 47-42725, No. 48-4871, Japanese Patent Application Laid-open No. 52-81727, etc. Although this method has some effects, it is not expected to produce a satisfactory large effect, and it is complicated by the need to pre-treat the joints of the webs.

On the other hand, as a method that does not require pretreatment of the web joint, coating is interrupted by pulling the hopper ξ− away from the coating roll just before the web joint passes through the coating bead, and after the joint passes, the hopper is returned to its original position. There is a method of returning to the position and applying the coating, but this method has the following problems. One of them is that when the hopper is pulled away and the coating is interrupted, during this interruption, the coating liquid is removed as shown in Figure 8. The coating liquid flows down the front wall of hopper ξ-, and the coating liquid adheres to the front wall of hopper ξ-, and over time, the composition of this adhered coating liquid, which dries and solidifies, peels off from the front wall of hopper ξ-. While forming a coating bead P, the bead portion comes into contact with the flowing coating liquid, causing uneven coating. The other one is that when you start coating again after discontinuing coating,
Bubbles and so-called "slips" (a phenomenon in which the coating liquid is repelled by the web surface t and does not stick partially) may occur, and the same disturbances and uneven coating of the coating layer as at the beginning of coating may occur. Also, during the interruption of coating, loss of web and coating liquid occurs.

The object of the invention is to eliminate the need for pre-treatment of web joints;
Moreover, the present invention provides a continuous coating method that can effectively reduce bubble peeling, coating unevenness, and disturbance of the coating liquid layer even when the joint portion of the web passes through the coating beer r.

The object of the present invention is to slightly separate the hopper from the coating roll (see Figure 4) so that the coating bead P is not separated from the web surface just before the joint of the web passes through the coating bead P. and the joint surface of the web, that is, the surface of the joint tape, is approximately the same or larger than the distance when coating the web surface other than the joint, and after the web joint passes through the coating bead y, This is achieved by returning Hola A- to its original position.

That is, the present invention provides a method for applying a coating liquid to a web having a running joint part using the P-P coating method, in which when the joint part of the web passes through the coating bee P, the coating liquid is applied to the web surface to the extent that it does not separate from the web surface. A coating method characterized in that the coating spatula P is moved in the opposite direction of the coating roll, and after the joint has passed, the coating head is moved again in the direction of the coating roll and returned to its original position, and the coating is continued. be. The shorter the time from when the coating spatula r is moved until it is returned to its original position, the less loss of coating occurs, so it is preferable.

Typical methods for applying P-P in the present invention include a method using a slide P hot-hole or an extrusion hopper.

In the present invention, the coating head is moved slightly when passing the coating bead at the web joint, but during that movement, the distance between the hopper tip and the joint tape surface at the joint is equal to that when coating the web surface other than the joint. The spacing is approximately the same or more than that, and the coating liquid does not leak from the web surface. This range varies depending on the viscosity of the coating liquid, etc., but the preferred range for carrying out the present invention is about 500 to 2,500.
μ, more preferably about 700 to 1.500 μ.

The coating liquid applied to the present invention is a light-sensitive inder containing natural or synthetic polymers such as silver halide photographic emulsions and organic polymer compounds such as gelatin, polyvinyl alcohol, and styrene-maleic anhydride copolymers. Various anionic, cationic, 4-tine, and nonionic surfactants are usually added to various non-photosensitive liquid fabric compositions as coating aids.

These coating liquids can be used on general paper, so-called Nono lighter paper whose surface is coated with Nonolium sulfate, polyethylene double-sided coated paper, polyethylene terephthalate film, polystyrene film,
It is coated on a web such as a polypropylene film in the form of one layer or a laminate of two or more layers.

In carrying out the present invention, a joint detection means is provided on the web travel path before the web reaches the coating head P, and based on this detection signal, when the joint reaches just before the coating head, By providing the coating spatula P actuating means so that the coating head is automatically activated, even high-speed coating can be carried out properly.

Next, the present invention will be explained in detail, but the present invention is not limited thereto.

Example Using a type 1 P-P coating device on the sliver shown in Figure 1, corona discharge treatment was applied to one side of a paper web whose both sides were coated with polyethylene, and then the coating liquid shown below was applied to that side by the following method. Coated in multiple layers at the same time. The support used was a 100 μm thick bonding tape with only one side of the coated side bonded butt-bonded. The coating speed was 60 m4, and the distance between the tip and the surface of the support was 850 μm.

Bottom layer: blue-sensitive gelatin containing yellow coupler
Silver halide emulsion. Wet coverage: 40 shoulders.

2nd layer: gelatin aqueous solution. Wet coverage: 15ha.

8th layer: green-sensitive gelatin containing magenta sol
Silver halide emulsion. Wet coverage: 85 pa.

Top layer: gelatin aqueous solution. Wet coverage: 15ha.

Incidentally, these coating liquids contained an appropriate amount of surfactant as a coating aid.

(Invention) 20c where the joint of the support passes through the coating bead
I moved the hole/e- instantly in front of the WL to make the distance between the tip of the hole and the joint tape surface 1,200μ, and immediately after passing the joint, I returned the hole to its original position. Although some disturbances occurred between the coated layers, continuous coating was carried out smoothly.

(Comparison 1) Continuous coating was carried out by passing the hopper through the support joint without moving the hopper at all, and immediately inspecting the coated area after the joint, streaky coating unevenness was discovered. As a countermeasure, we lowered the hopper to the rear, temporarily stopped coating, cleaned the tip of the hopper, removed the cause of the uneven coating, and then started coating again. It took a considerable amount of time to discover streaky uneven coating after passing through the joint, and bubbles, repelling, and uneven coating occurred for a while when coating was restarted. Also, stop the application and
During cleaning of the tip, the running web and the supplied coating fluid are lost.

(Comparison 2) 20c where the joint part of the support passes through the coating bee P
IrL front f hot zo-20. , the coating was temporarily interrupted by moving the hopper backwards, and immediately after passing the joint, the hopper was returned to its original position and continued coating was performed. When it was returned, bubbles, repellency, and uneven coating occurred, and it took time to return to a stable state of 1 original.

The table below shows the amount of discarded coated web and the web loss (ie, the web that passed through without being coated) caused by the above-mentioned inventive and comparative coating methods.

From the above results, it is clear that compared to the comparison, the amount of discarded coated web when passing through the joint is extremely small, and there is no web loss, so it is effective in improving productivity and reducing costs! be.

[Brief explanation of drawings]

Figures 1 to 4 show the coating situation using a slide hole/ξ-type B-P coating device. Figure 1 is a schematic diagram showing the normal coating situation, and Figure 2 is a comparison. 1.8th
Comparison 2 and FIG. 4 are schematic diagrams showing the coating situation of the embodiment of the present invention. 1...Coating roll 2...Coating spatula P 8.3'...Web 4...Coating fluid 5...Joining tape 1st F ! ! i Figure 3

Claims (1)

[Claims] (1) In a method of applying a coating liquid to a web having a running joint part using the bee Y coating method, when the joint part of the web passes through the coating bead P, the coating bead part 1
The coating head is moved in the opposite direction of the coating roll to the extent that the coating liquid does not separate from the web surface, and after passing the joint, the coating head is moved in the direction of the coating roll and returned to its original position to continue coating. A coating method characterized by: