JP2891360B2 - 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 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 web double-sided coating technology, various means,
Methods are known.

For example, a method in which a web is coated on one side and gelled, and then the gelled side is directly contacted with a supporting roll and continuously coated on the opposite side (Japanese Patent Publication No. 48-44171). Alternatively, a gas is ejected from a rolled surface with slits to lift the web, and the coating machine (coater)
By pressing the tip of the web onto the web (Japanese Patent Publication No. 49-
No. 17853).

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.

If the peripheral speed of the support roll slightly deviates from the web transport speed, the gelled coating layer is also greatly disturbed.

Also, in the technique described in Japanese Patent Publication No. 49-17853, when the width of the web is large, the difference in the floating amount in the width direction of the web becomes large, and the tip of the coating machine cannot be pressed evenly on the web. It is difficult to obtain a uniform coating amount over a wide range.

Since no consideration is given to suppressing the vibration of the web 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 have provided a coating unit in which a coater and a gas ejector are disposed substantially opposite to each other with a continuously running web interposed therebetween, and eject a gas from the gas ejector to generate a web. A method and an apparatus for applying a coating while supporting the surface of the web have been proposed, and have been put to practical use mainly for double-sided web application (Japanese Patent Application No. 56-175801).

[Problems to be solved by the invention]

However, in the above-described conventional apparatus, when the web has a certain width or more, the flying height distribution in the width direction of the web floating and supported by the gas ejector changes, and the bead gap becomes non-uniform. In some cases, the film thickness fluctuated or coating unevenness occurred.

That is, if the distribution of the static pressure generated in the gap between the web and the gas ejector in the width direction (hereinafter referred to as "back pressure distribution") is ideally maintained, the web supported by the gas ejector is supported by the fourth condition.
As shown in FIG. 9A, the flying height in the width direction is symmetrical, and the flying height can be made substantially uniform. However, the running position in the width direction of the web changes relatively easily due to a small difference in the shape of the web mainly due to manufacturing conditions. On the other hand, since the back pressure distribution greatly changes due to a change in the running position of the web on the gas ejector and the front and rear of the web in the width direction, the flying height in the width direction is shown in FIGS. A significant change in the distribution occurs.
As a result, the bead gap becomes non-uniform, causing a variation in coating film thickness and coating unevenness.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a web coating apparatus capable of always maintaining a constant flying height distribution in a width direction even when a web disturbance in a floating supporting state is applied.

[Means for solving the problem]

In order to achieve the above object, the present invention includes a coating unit provided with a coater and a gas ejector at positions substantially opposite to each other across a continuously running web, and ejects gas from the gas ejector. In a web coating apparatus for performing coating while floatingly supporting the web, at least one of a front portion and a rear portion of the coating section is provided, and a baffle guide for regulating a gas ejector and a running position of the web on the gas ejector is provided. A web running position adjusting means comprising a plate is provided.

〔Example〕

Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing the overall configuration of the web application apparatus of the present application, and FIG. 2 is a case where a traveling position adjusting means is a binaural guide plate of a web on a gas ejector provided at a rear portion of an application section. FIG. 3 is a perspective view of the vicinity of the application section, and FIG. 3 is a perspective view of the vicinity of the application section when the traveling position adjusting means is a web support roll.

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. The coaters 1 and 2 are provided with spring slits 1a and 1b and 2a and 2b, respectively, so that two-layer coating can be performed by the coating liquid L that springs from the spring slits 1a and 1b and 2a and 2b.

That is, the first coater 1 forms an application section T ₁ where the application liquid L is applied to the surface 3 a of the web 3 near the introduction section D ₁ to form a coating film.
The second coater 2 constitutes the coating section T ₂ which forms a coating film on the back surface 3b of the web 3 in the vicinity of derivation unit D ₂ respectively, are configured to be implemented on both sides coating of the web 3.

The web 3 is supported in contact with an auxiliary roller 4 and
After being carried into D ₁ , it is wrapped around by being contacted and supported by the main roller 5, and when passing near the first coater 1, the coater 1
And is conveyed to the cool air zone 6.

Reference numerals 7 and 8 decompress chambers, and the decompression chambers 7 and 8 appropriately aspirate a bead of the coating solution L (a coating solution cross-linked from the coater to the web surface) from each of the coaters 1 and 2, and apply the coating solution L to the coating solution. This is for stabilizing the transfer to the web surface. Of the decompression chamber 7,8, the one chamber 7 and the lower side of the bead gap B ₁ of the first coater 1, the other chamber 8 respectively 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 surface 3a of the web 3 to promote gelation of the coating film,
A conveying roller group 9 for conveying while cooling by supporting the back surface 3b (uncoated surface) of the web 3 in contact, and a front surface of the web 3
Small holes (or) for cooling by applying cool air to 3a (the already applied surface)
And a slit group 10. The temperature in the cool air zone 6 depends on the coating conditions (temperature of the coating liquid L, thickness of the coating film, coating speed, etc.) and web running conditions (web temperature, web thickness, web running speed, etc.). The temperature of the web 3 when it is conveyed to the second coater 2 after exiting the cold air zone 6
It is adjusted to be around 10 ° C.

Reference numeral 11 denotes a gas ejector. The gas ejector 11 floats and supports the web 3 around the second coater 2 to form a coating film of the coating liquid L on the back surface 3b (uncoated surface). It is for. That is, the web holding surface 11a of the outer shell of the gas ejector 11 is formed of a smooth cylindrical surface, and the gas inside the gas ejector 11 is transferred to the surface 3a of the web 3 through the minute gas ejection holes F provided on the surface. The coating is performed by the coater 2 while protecting the surface 3a (the already applied surface) of the web 3 so that the web 3 can be floated and conveyed. The non-web holding surface 11b facing the web holding surface 11a does not need to be a cylindrical surface, and may not include the minute gas ejection holes F.

Wherein at least one front or rear of the coating section T ₂ are, position adjusting means 12 for adjusting the travel position in the width direction of the web 3 is provided. The position adjusting means 12,
It is possible to prevent the web 3 during the floating traveling from being displaced in the width direction in the vicinity of the coating portion, leading to a change in the back pressure distribution and falling into an uneven floating state as shown in FIGS. 4 (b) and 4 (c). It is for doing. Although various configurations of the position adjusting means 12 are conceivable, as shown in FIG. 2, both ears of the web 3 are guided on a gas ejector 11 ′ provided separately from the coating section to adjust the running position of the web. It may be configured as binaural guide plates 121, 121 'for regulating, or as shown in FIG.
A web supporting roll 12 composed of a gas ejector whose angle can be adjusted in a direction in which it is not parallel to 11 ′ (direction of arrow II ′).
It may be configured as 2,123.

That is, in FIG. 2, both ears guide plates 121 and 121 'are disposed on the gas ejector to be slightly wider than the web 3, provided at a rear portion of the coating section T ₂ second coater 2 (downstream side) , Can move on the gas ejector 11 'in the width direction of the web 3 (the direction of the arrow ロ'). According to the flying height distribution of the web 3, the binaural guide plates 121 and 121 'can guide and restrict the ear position of the web 3 by the side walls 121a and 121a' so as to eliminate the non-uniform state of the flying height. ing.

Here, various methods for monitoring the flying height distribution of the web 3 can be considered. For example, the web holding surface 11 of the gas ejector 11 can be monitored.
In a, a plurality of non-contact sensors (not shown) for measuring the gap with the web 3 may be provided at appropriate places in the width direction.

In addition, guide plates 121, 12
The direction to move 1 'is from the larger flying height to the smaller flying height.How much to move should be determined by collecting actual measurement data and referring to it, and gradually guiding while monitoring the flying height It may be determined in such a manner that the movement is stopped when the flying height is balanced by moving the plate.

As described above, if the gap sensor and the arithmetic processing unit are combined, the moving positions of the guide plates 121 and 121 'are configured as an automatic control system. In FIG. 2,
Reference numeral 13 denotes a web support roll composed of a gas ejector.

In the third diagram, the web support rolls 122 composed of gas ejector is provided at a rear portion of the coating section T _2, tilting the support roller 122 to gas ejector 11, the web in accordance with the tilt angle It moves in the width direction, the relationship between the running position of the web in the width direction on and before and after the gas ejector 11 is changed, the back pressure distribution is adjusted, and the non-uniform state of the flying height is eliminated. It is supposed to be. That is, web 3
Tries to run in a direction perpendicular to the center axis of the support roll 122, so that if the center axis is inclined, the running direction will be changed left and right.

In order to further ensure the interaction between the web supporting roll 122 and the web 3, it is preferable that the web holding angle θ of the web supporting roll 122 be 90 ° or more. The automatic control system may be configured by appropriately combining the inclination angle of the web support roll 122 with respect to the gas ejector 11 with a gap sensor and an arithmetic processing unit as in the case of the guide plates 121 and 121 '.

In some cases, placing the web support rolls 123 as a position adjusting means 12 to the front (upstream side) of the coated portion T _2. In this case, a contact roll may be used depending on the state of the application surface. This web support roll 123 is also a gas ejector 11
The angle can be adjusted in a non-parallel direction (the direction of the arrow c-a '). In short, any configuration is possible as long as the running position of the web in the width direction can be changed before and after the center of the gas ejector 11. However, when the contact type roll is used, the surface 3a which is the coated surface of the web 3 cannot be supported, and the interaction between the roll and the web is so strong that the web winding phenomenon or the web vibration is not caused. It is desirable to consider the adjustment of the hugging angle.

The gas used for levitation support by the gas ejector (including the support roll used as the web position adjusting means 12) may be any gas such as N ₂ gas, air, or the like, as long as there is no problem with safety. There is air.

The coated web is coated on the opposite surface in the floating support portion, then passes after the coating layer was gelled while applying cold air to both sides in a state of non-contact at cold zone (not shown), a lead portion D ₂ No It is conveyed to the contact drying zone. Even if the coated web 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 absorbed by the floating support portion. As a result, uniform application is possible without propagation.

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 the conveying roller 9 while receiving the cool air from the small hole group 10 in the cool air zone 6, and the web 3 is heated to 10 °
It is cooled back and forth and transported to the gas ejector 11. The back surface 3b is applied by the second coater 2 to the web 3 in which the surface 3a in the already applied state is floated and supported by the gas ejected from the gas ejection hole F of the web holding surface 11a of the gas ejector 11.
At this time, the balance of the flying height distribution of the web 3 may be lost due to the bias of the back pressure distribution on the web holding surface 11a. However, the flying height distribution is appropriately corrected by the web position adjusting means. That is, both ear guide plates 121, 12 of the web
The web 3 is moved to the appropriate position in the width direction by moving the 1 'in the width direction to adjust the position, or by adjusting the angles of the rolls 122 and 123 formed of gas ejectors in a direction non-parallel to the gas ejector 11. Is done.

As a result, the flying height distribution also not occur changes uniformly from maintained bead gap B _1, B ₂ is always uniform coating condition, the web 3 that has been uniformly applied to both surfaces is derived from the deriving unit D _2, It is transported to the cooling / drying step, and the double-sided coating step is completed.

In addition, as a web to be used in the present invention, a plastic film such as polyethylene terephthalate or cellulose triacetate, or a web for photographic photosensitive materials such as paper can be used.

There is no particular limitation on the material constituting the curved surface of the floating support portion, and any material can be used as long as it can withstand the internal pressure of the hollow portion. Brass steel or stainless steel with hard chrome plating on the surface is desirable. When providing the through holes as in the case, a plastic material such as bakelite or acrylic resin can be used in consideration of the ease of drilling.

In practicing the present invention, the gas collides with the gelled coating layer in the floating support portion, but enters the floating support portion in order to prevent the coating layer from being disturbed by the dynamic pressure of the gas. The temperature of the coating layer immediately before is 10 ° C
It is desirable to increase the gel strength of the coating layer by lowering it back and forth.

Although the embodiment has been described above, the embodiment of the present invention is not limited to this, and the gas ejector has a continuous curved surface as the outer surface of the floating support portion in the gap between the web and the web to maintain a high static pressure. However, any gas can be ejected from the curved surface as long as the condition of the present invention is satisfied.

That is, the outer shape does not need to be a roll, and the portion that allows gas to pass from the inside to the outside of the gas ejector does not need to be a through hole, and may be a coating apparatus provided with a gas ejector of another configuration. For example, the shape of the gas ejector may be a semi-cylindrical shape or an elliptic cylindrical shape, or only the floating support portion may have a curvature on the outer surface, and the other may have a flat shape.

On the other hand, the section through which the gas supplied to the inside of the gas ejector passes to the outside plays a major role in passing the gas and providing pressure loss. Alternatively, a type in which a porous body P of a sinterable metal or the like forms the outer wall of the gas ejector of the floating support portion may be used.

Further, it is also possible to make the gas ejector from the gas inlet to the outer surface of the floating support portion, without making the gas ejector hollow, by the porous body as described above.

〔The invention's effect〕

As described above, the present invention includes a coating unit provided with a coater and a gas ejector at positions substantially opposite to each other with a continuously running web interposed therebetween, and ejects gas from the gas ejector to remove the web. In a web coating apparatus that performs coating while supporting the device in a floating manner, the web coating device includes a gas ejector and a binaural guide plate that regulates a running position of the web on the gas ejector, in the vicinity of at least one of a front portion and a rear portion of the coating portion. Since the web running position adjusting means is provided, it is possible to arbitrarily adjust the web running position in the vicinity of the coating section. For this reason, by maintaining a uniform bead gap by optimizing the web floating amount, a coating film having a uniform thickness and surface state is realized, which has a great effect on high quality web and stable production. Things.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the overall configuration of the web application apparatus of the present application, and FIG. 2 is a case where a traveling position adjusting means is a binaural guide plate of a web on a gas ejector provided at a rear portion of an application section. FIG. 3 is a perspective view of the vicinity of the application section when the travel position adjusting means is a web support roll, and FIG. 4 is an explanatory view showing a change in the flying height due to a positional displacement of the web travel in the conventional apparatus. It is. 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 rollers 10… Small holes 11… Gas ejector 11a… Web holding surface 11b… Non-web holding surface 12… Position adjusting means 121,121 ' ₁ ... Introducing section D ₂ ... Outgoing section B ₁ , B ₂ ... Bead gap T ₁ , T ₂ ... Coating section L... Coating liquid F.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-63164 (JP, A) JP-A-62-163773 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B05C 5/00-5/04 B05D 1/00-7/26

Claims (1)

(57) [Claims] 1. A coating section provided with a coater and a gas ejector at positions substantially opposite to each other with a continuously running web interposed therebetween, and the gas ejector ejects gas to float and support the web. In a web coating apparatus which performs coating while performing web coating, a web running including a gas ejector and a binaural guide plate for regulating a running position of the web on the gas ejector is provided near at least one of a front portion and a rear portion of the coating portion. A web coating device comprising a position adjusting means.