JP2577622B2 - Web coating device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for floatingly supporting a web (belt-shaped flexible support) to apply a coating liquid to a very uniform film thickness.

More specifically, the surface opposite to the coated surface of the photographic photosensitive material or the like is continuously run while floating and supported.
The present invention relates to an apparatus for applying one or more kinds of application liquids, and more particularly to a web application apparatus suitable for performing continuous double-side application.

[Conventional technology]

Conventionally, as a double-sided coating technology of the support, various means,
Methods are known.

For example, a method in which a coating is applied to one surface of a support, gelled, and then the gelled surface is brought into direct contact with a supporting roll to continuously apply the coating to the opposite surface (Japanese Patent Publication No. 48-44171). A method in which a support is levitated by ejecting gas from a roll surface having a slit to apply the coating by pressing the tip of a coating machine (coater) against the support (Japanese Patent Publication No. 49-17853).
No.) are known.

However, in the above prior art, even if there is a slight dust or scratch on the support roll that supports the gelled surface, the gelled application surface is disturbed, and a part of the coating layer adheres to the roll. The same is true even if it remains, and maintenance is extremely difficult.

Even if the frequency of the support roll slightly deviates from the transport speed of the support, the gelled coating layer is also greatly disturbed.

Also, with the technique described in Japanese Patent Publication No. 49-17853, if the width of the support increases, the floating amount difference in the width direction of the support increases, and the tip of the coating machine cannot be pressed evenly against the support. It is difficult to obtain a uniform coating layer over the entire surface of the support.

Since no consideration is given to vibrating the support before and after the coating machine, coating unevenness is likely to occur.

Since this method is a method of pressing a coating machine, there is a drawback that a bead coating method such as a slide hopper generally used for coating a photographic light-sensitive material cannot be applied.

For this reason, the present inventors consider a coater and a gas ejector at a position substantially opposite to each other with a continuously running support interposed therebetween, and eject gas from the gas ejector toward the support. Thus, a coating method and an apparatus for performing coating by the coater while floating and supporting the support have been proposed and put to practical use (Japanese Patent Application No. 56-175801).

[Problems to be solved by the invention]

In the above-mentioned conventional technology, it is completely unknown how the bead gap (the interval between the coater and the web) changes in the coating process and how it affects the state of the molten film.

That is, when the web is applied by floating and supported by a gas ejector, the beat gap changes depending on various conditions such as the thickness, hardness, and tension of the web, and as a result, the state of the coating film may also change. Known empirically. Therefore, the position of the coater has been adjusted according to the type of web, but there are many factors depending on the skill of the skilled worker, and there has been a problem that quick and accurate adjustment cannot be performed during web application. For this reason, the occurrence of coating failure due to the change in the bead gap cannot be avoided, and this has caused a decrease in productivity and yield.

SUMMARY OF THE INVENTION In view of the above, it is a first object of the present invention to provide a web coating apparatus capable of detecting a change in a bead gap accurately and in real time. It is a second object of the present invention to provide a web coating apparatus capable of changing a coater position at any time according to a change in a bead gap and maintaining an optimum coating state.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a coater and a gas ejector at positions substantially opposite to each other with a continuously running web interposed therebetween. In a web coating apparatus which performs coating by the coater while floating and supporting the web by ejecting gas from the container toward the web, a web holding surface portion of the gas ejector includes a space between the coater and the gas ejector. And a plurality of sensors for measuring the distance between the jetting device and the web are provided in the width direction of the web so that a change in bead gap can be directly detected in real time.

Further, a driving means for moving the coater forward and backward according to the output of the sensor is provided in the coater, and a drive system capable of automatically controlling the position of the coater according to a change in the bead gap is configured.

〔Example〕

Hereinafter, the present invention will be described with reference to an embodiment shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the entire structure of the coating apparatus of the present invention, FIG. 2 is a horizontal sectional view showing the relationship between a gap sensor, a coater, a web, and a gas ejector, and FIG. Is a block diagram showing the configuration of a drive system, FIG. 4 is a perspective view of a bead gap, FIG. 5 is a cross-sectional view showing another example of a gas ejector, and FIG. 6 is a gas ejector using a porous body. It is sectional drawing which shows the example of.

In the figure, reference numeral 1 denotes a first coater, 2 denotes a second coater, and the first and second coaters 1 and 2 are an introduction portion D of the web 3.
Respectively provided in this order on the _first and derivation unit D _2. Further, the coaters 1 and 2 respectively have spring slits 1a, 1b, and 2a,
2b, the two-layer coating can be performed by the coating liquid L flowing out from the slits 1a, 1b and 2a, 2b. That is, the first coater 1, web 3 in the vicinity of inlet portion D ₁
On the surface 3a of the second coater 2 web 3 in the vicinity of derivation unit D ₂
The coating liquid L is applied to the rear surface 3b of the web 3 so that the web 3 can be coated on both sides. The second coater 2 is provided with a roller R or a suitable sliding means, and can be moved forward and backward by a driving means 17 described later.

The web 3 is supported in contact with an auxiliary roller 4 and
After being carried into D ₁ , it is wrapped around while being contacted and supported by the main roller 5, passes near the front and rear first coater 1, is coated on the surface 3 a by the coater 1, and is conveyed to the cool air zone 6. Has become. 7, 8 are decompression chambers.
Is used to stabilize the transfer of the coating liquid L to the web surface by appropriately sucking a beat (a coating liquid cross-linked from the coater to the web surface) composed of the coating liquid L of each of the coaters 1 and 2. It is. The chamber 7 is lower bead gap B ₁ of the first coater 1, the chamber 8 are provided on the lower side of the bead gap B ₂ of the second coater 2.

The cold air zone 6 is for cooling the coating liquid L applied to the front surface 3a of the web 3 to promote gelation, and is cooled by contacting and supporting the back surface 3b (uncoated surface) of the web 3. Roller group 9 for conveying while moving, and the surface 3a of the web 3
A small hole (or) slit group 10 for cooling by applying cold air to the (applied surface). The temperature in the cool air zone 6 is determined by the coating conditions (temperature of the coating liquid L, thickness of the coating film, coating speed, etc.).
In general, the temperature of the web 3 when it leaves the cold air zone 6 and is conveyed to the second coater 2 is 2 to 15 ° C., although it depends on the web running conditions (web temperature, web thickness, web running speed, etc.).
It is adjusted to be back and forth.

Numeral 11 denotes a gas ejector. The ejector 11 floats and supports the web 3 to protect the front surface 3a (the already coated surface) of the web 3 and wraps the web 3 in the vicinity of the second coater 2, and the back surface 3b (uncoated surface)
For applying the coating liquid L to the substrate. That is, a large number of minute ejection holes F are provided on the web holding surface 11a of the outer shell of the gas ejector 11, and are ejected toward the surface 3a of the gas web 3 in the ejector 11, and the web is applied while being coated by the coater 2. 3
Can be levitated and conveyed (FIG. 4).

Are web gap sensors, and the gap sensors 12, 12, ... are gas ejectors facing the second coater 2.
A plurality of locations (four locations in FIG. 2) are provided in the outer shell at appropriate locations along the width direction. The sensor 12 is a gas ejector 11
For measuring the gap between the surface of the web and the web 3.
The distance between the web 3 and the gas ejector 11 can be measured by a non-contact method. Although an optical distance sensor is used in this embodiment, for example, a capacitance sensor or an ultrasonic sensor may be used.

13, 13, ... are coater gap sensors.
, 3,... Are located at appropriate places on the outer shell of the gas ejector 11 facing the second coater 2 and adjacent to the sensors 12, 12,.
At a plurality of locations in the width direction. The sensor 13 is
This is for measuring the distance between the gas ejector 11 and the second coater 2. In this example, an eddy current type distance sensor is used. However, for example, a web such as a capacitance type sensor or a discharge line type sensor is damaged. Anything can be used as long as it can measure the gap between the coater and the gas ejector without using it.

The outputs of the sensors 12 and 13 are output to a signal processing unit 14 and an arithmetic processing unit 15.
After the processing, the data is stored in the memory 16 as appropriate.

Reference numeral 17 denotes a drive unit, which is a drive system for adjusting the position of the second coater 2 in accordance with the outputs of the sensors 12 and 13, and is a servomotor device that can be electrically controlled. (Fig. 3). That is, the drive unit 17 digitizes the outputs of the sensors 12 and 13 by the signal processing unit 14, and then moves the position of the second coater 2 forward and backward as appropriate in accordance with the command value calculated by the arithmetic processing unit 15 by a predetermined algorithm. controlled by, and to be able to maintain the bead gap B ₂ to the optimum state. The driving means 17 may be configured to move back and forth by, for example, a voice coil type actuator or an electrostrictive actuator. Furthermore, it may be configured to be controlled appropriately disposed to bead gap B ₂ by bending the coated side edge of the coater 2 a plurality of driving means.

Thus, the web 3 of the double-sided uncoated is carried into the inlet portion D ₁ supported in contact with the auxiliary roller 4, wraparound in the vicinity of the first coater 1 while being in contact supported by the main rollers 4, gush gush slit 1a, a 1b The coating liquid L is applied to the surface 3a in two layers. Next, the web 3 is contact-supported and conveyed by conveying rollers 9 while receiving the cool air from the small hole group 10 in the cool air zone 6, and cooled to about 2 to 15 ° C.
Transported to The back surface 3b is applied by the second coater 2 to the web 3 in which the front surface 3a in the applied state is floated and supported on the web holding surface 11a of the ejector 11. Here, the web 3 varies depending on various conditions such as a variation in tension of the web 3, a variation in ejection pressure of the gas ejector 11, and a variation in pressure in the decompression chambers 7 and 8.
When the distance between the web 3 and the gas ejector 11 and / or the distance between the web 3 and the coater 2 change, the change is output by the gap sensors 12 and 13 accurately and in real time. Next, the outputs of the sensors 12 and 13 are written to the memory 17 via the signal processing unit 14 and the arithmetic processing unit 15, and the command is output to the driving means 16 to control the position of the second coater 2 to the optimum position.
However, the movement of the coater 2 is controlled within a range that does not exceed a predetermined speed and frequency, because if it is performed suddenly, it will adversely affect the coating. As a result, the bead gap B ₂ is always maintained at an optimum state regardless of a change in application conditions. Then, the web 3 which is uniformly coated on both sides are derived from the deriving unit D _2, conveyed sided coating process is finished to the cooling and drying process.

The gas used for levitation support in the present invention is N ₂
Anything that does not pose a safety problem, such as gas or air, may be used, but air is most commonly used. The coated web applied to the opposite surface in the floating support portion is then transferred to a non-contact drying zone after the coating layer is gelled while applying cold air to both surfaces in a non-contact state in a cold air zone (not shown). . Even if the substrate to be coated fluctuates (or vibrates) in the direction perpendicular to the running direction in the non-contact gelling portion or the non-contact drying zone, it is not absorbed and propagated in the floating support portion, and It turned out that application was possible.

The web to be used in the present invention may be a plastic film such as polyethylene terephthalate or cellulose triacetate, or a web for photographic photosensitive materials such as paper. Further, the material constituting the curved surface of the floating support portion is not particularly limited, and any material can be used as long as it can withstand the internal pressure of the hollow portion, but brass steel or stainless steel having a hard chrome plating on its surface is desirable,
When providing the through holes as in this case, a plastic material such as bakelite or acrylic resin can be used in consideration of the ease of drilling.

Further, in practicing the present invention, in order to prevent the gas from colliding with the coating layer to be gelled in the floating support portion and to prevent the coating layer from being disturbed by the dynamic pressure of the gas, just before entering the floating support portion. It is desirable to raise the gel strength of the coating layer by setting the temperature of the coating layer to 2 to 15 ° C.

Although the present invention has been described above, the embodiment of the present invention is not limited to this, and the gas ejector has a continuous curved surface to maintain a high static pressure in the gap with the web in the floating support portion. Any shape can be used as long as the gas can be ejected and the conditions of the present invention are satisfied. The outer shape is a roll shape, and the portion that allows the gas to pass from the inside to the outside of the gas ejector must be a through hole. Instead, a coating device having a gas ejector of various configurations may be used. For example, the type of the gas ejector may be a semi-cylindrical or elliptical cylinder, or only the floating support portion as shown in FIG. 5 showing another example of the gas ejector may have a curvature on the outer surface, and the other may be flat. It may be a shape composed of On the other hand, the part that allows the gas supplied to the inside of the gas ejector to pass to the outside plays a major role in passing the gas and giving a pressure loss. As long as this condition is satisfied, any type may be used. In the case of forming a through-hole, the shape may be a round hole or a polygonal hole, and as shown in FIG. It may be of a type that forms the outer shell of the gas ejector of the non-contact support portion. Further, it is also possible to constitute the gas ejector from the gas inlet to the outer surface of the non-contact support portion, without making the gas ejector hollow, as described above.

In addition, as a method of coating on one side and the other side of the web to be coated, a conventionally known method such as a bead coating method or an extrude coating method can be used.

〔The invention's effect〕

As described above, according to the present invention, a coater and a gas ejector are disposed at positions substantially opposite to each other across a continuously running web, and gas is ejected from the gas ejector toward the web. Thus, in a web coating apparatus that performs coating by the coater while floatingly supporting the web, a distance between the coater and the ejector and a distance between the ejector and the web are measured on a web holding surface portion of the gas ejector. Since a plurality of gap sensors are provided in the width direction of the web, the relationship between the bead gap and the coating failure can be grasped numerically accurately and in real time. Therefore, if the output of the gap sensor corresponding to the web application position is stored in the memory,
The defective part of the product web can be easily estimated, which contributes to quality control and yield improvement.

Further, the optimum coater position is determined by appropriately processing the output of the sensor, and if the coater is moved by the driving means in accordance with the command, the bead gap can always be controlled to the optimum interval, and the coating state is always maintained in the optimum state. be able to. As a result, various excellent effects can be achieved by stabilizing the coating process, improving the coating quality, and automating the work of adjusting the beat gap.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the entire structure of the coating apparatus of the present invention, FIG. 2 is a horizontal sectional view showing the relationship between a gap sensor, a coater, a web, and a gas ejector, and FIG. Is a block diagram showing the configuration of a drive system, FIG. 4 is a perspective view of a bead gap, FIG. 5 is a cross-sectional view showing another example of a gas ejector, and FIG. 6 is a gas ejector using a porous body. It is sectional drawing which shows the example of. 1 ... First coater 2 ... Second coater 3 ... Web 3a ... Web surface 3b ... Web back surface 4 ... Auxiliary roller 5 ... Main roller 6 ... Cool air zone 7, 8 ... Decompression chamber 9 ... … Conveying roller group 10… Slit group 11… Gas ejector 11a… Web holding surface 11b… Non-web holding surface 12… Web gap sensor 13… Coater gap sensor 14… Signal processing unit 15… Calculation processor 16 ...... memory 17 ...... driving means D ₁ ...... introduction portion D ₂ ...... derivation unit B _1, B ₂ ...... bead gap F ...... fine ejection holes P ...... porous body

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Tomohide Mizukoshi 1 Konica Sakuracho, Hino-shi, Tokyo Inside Konica Corporation (56) References JP-A-59-162977 (JP, A) JP-A-63-4870 ( JP, A)

Claims (2)

(57) [Claims] 1. A coater and a gas ejector are disposed at positions substantially opposite to each other with a continuously running web therebetween.
In a web coating apparatus in which a gas is ejected from the gas ejector toward the web to perform application by the coater while supporting the web in a floating manner, the coater and the ejector are provided on a web holding surface portion of the gas ejector. A web coating apparatus, wherein a plurality of sensors for measuring the distance between the containers and the distance between the jetting device and the web are provided at a plurality of positions in the width direction of the web. 2. A web coating apparatus according to claim 1, wherein said coater is provided with a driving means for moving the coater forward and backward in accordance with the output of said sensor.