JPS63287574A - Method and equipment for coating - Google Patents

Abstract

PURPOSE:To prepare a uniform film thickness by supporting both ends of film- like coating liquid with supplementary liquid discharging along the flowing film of the coating liquid in a jet state with an angle in the outside direction when film-like coating liquid is struck against a supporting body to be coated. CONSTITUTION:One or more kinds of film-like coating liquids 11-13 is struck against a supporting body 2 to be coated. Then, both ends of the film-like coating liquid are supported by supplementary liquids 5a, 5b which spout in a jet state along the effluent film of said coating liquid with an angle theta to the outside direction. As a result, even though a curtain film is high or an edge guide is not applied, no local thick coats occur on both side edge parts in the web direction and it is possible to obtain a constant and stable coating film.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a coating method and apparatus.

In particular, in the production of recording materials such as photographic light-sensitive materials such as photographic film and photographic paper, and magnetic recording materials such as magnetic recording tape, a continuously running long strip-shaped support (hereinafter referred to as a "web") is used.
This relates to a method of applying a coating liquid such as a photographic emulsion or a magnetic agent to a surface ().

More specifically, the present invention relates to a method and apparatus for applying one or more types of coating liquid in the form of a thin film by colliding with a support to be coated.

[Conventional technology]

Among the methods of applying a thin film of coating solution by colliding with a support, a typical method is the curtain coating method.

The curtain coating method is a method in which a free-falling curtain made of one or more coating liquids is formed and the curtain is made to collide with the object to be coated to form a coating film on the object. However, due to the demand for improved coating quality, high-precision coating is gradually required, and in recent years Japanese Patent Publications No. 49-24133 and No. 49
As disclosed in Japanese Patent No. 35447, attempts have been made to apply the curtain coating method to fields where precision is particularly required, such as the production of photographic materials.

The method disclosed in Japanese Patent Publication Nos. 49-24133 and 49-35447 involves supplying one or more coating liquids between two edge guides using a slide type or extrusion type liquid injection device. This method forms a thin, free-falling curtain that is applied to a continuously running web. The reason why the coating liquid is supplied between the two edge guides is to regulate the coating width and to stabilize the curtain film.

When coating is performed using such a fixed edge guide, if the coating liquid leaves the part supported by the edge guide even slightly, the coating liquid contracts. As shown, coating liquids 11, 12, 13
It has been found that when the coating film is applied to the surface of the web 2, the thickness of the coating film at both side edges in the width direction of the web is thicker than that at the center.

Such a phenomenon has been observed even when the clearance between the lower end of the edge guide and the web is reduced to almost zero.

This phenomenon occurs in addition to the general flow contraction caused by interfacial tension, etc.
When a fixed edge guide is used, an uneven distribution of the falling speed of the coating liquid near the edge guide inevitably occurs. In other words, the falling speed of the coating liquid near the edge guide is lower than the falling speed of the coating liquid at the center of the curtain film. Due to the phenomenon that the liquid falling speed is small (that is, the falling momentum is small), it is not possible to break through the air layer adhering to the web, and when a certain amount of liquid accumulates in the contraction flow (momentum increases). It can be assumed that this is because it is coated.

In order to solve the above-mentioned drawbacks, the method and apparatus disclosed in Japanese Patent Publication No. 58-37866 is such that both ends of the coating liquid film are cut at the lower end of the nozzle guide, as shown in FIGS. 4 and 5. It was supported by a liquid (auxiliary liquid) that was jetted out in the same direction as the outflow direction.

That is, in FIGS. 3 and 4, the coating liquid 21 is fed by an extrusion type liquid injector 24 by a bomb (+@not shown), and is passed through the slot 24S to the edge guide 23a,
23b. The edge guides 23a and 23b are made of a member having a smooth surface and a clear water surface property, such as a stainless steel plate, one end of which is in close contact with the tip of the slot 24S of the liquid injector 24, and the other end is located a little from the top surface of the backup roll 25. The curtain film 21 of the coating liquid 21 flowing down from the slot 24S is provided so as to come to the open positions d-1 to d-5.
C is held from the width direction and the coating width is regulated. Below the edge guides 23a and 23b is a pipe 2 with a small inner diameter.
6a and 26b are embedded in the edge guides 23a and 23b, respectively. The rear ends of the pipes 26a and 26b are jet/
& (auxiliary liquid) supply tank (not shown), jet liquid (auxiliary liquid) discharge ports 26ha and 26hb at the tip thereof coincide with the flow direction of the curtain membrane 21c, and the center of the hole of the auxiliary liquid discharge port is in the curtain membrane. It is provided so as to be located approximately on the side edge of 21C.

The auxiliary liquid 27 is connected to the auxiliary liquid discharge ports 2'6 ha and 26 h.
b is discharged in a jet form along the side edge of the curtain 1121c, and is applied onto the web 2 while supporting the curtain film 21C.

As described above, the flow rate of the coating liquid 21 is actively increased by the auxiliary liquid 27, so that the curtain film 21C is applied from the lower ends of the edge guides 23a and 23b to the surface of the web 2 without contracting. It is.

The auxiliary liquid 27 supplied to the pipes 26a and 26b varies depending on the properties of the coating liquid 21 used, but is generally a fluid that does not impair the original physical properties of the coating liquid 21, and is a fluid that does not impair the original physical properties of the coating liquid 21. A liquid is selected that has a surface tension sufficient to hold the side edges of the liquid.

[Problem that the invention seeks to solve]

However, when using the above method and apparatus, as the height of the curtain film increases or as the distance from the tip of the edge guide to the top surface of the application roll increases, the flow velocity of the auxiliary liquid discharged in a jet stream increases. This has resulted in the disadvantage that the flow rate of the coating liquid is relaxed by the flow rate of the coating liquid film, and the surface tension of the coating liquid causes contracture flow in the curtain film, resulting in localized thick coating areas at both edges in the width direction of the web.

The present invention eliminates the above-mentioned drawbacks of conventional coating methods, and even if the height of the curtain film is increased or without using an edge guide, uniform coating is achieved without local thick coating on both edges in the width direction of the web. The purpose of the present invention is to provide a coating method that allows a stable film thickness to be obtained.

Another object of the invention is to provide an apparatus for carrying out the above method.

c. Means for Solving Problems] The present invention provides a first aspect of the present invention, which provides a coating method in which one or more coating liquids in the form of a thin film are applied by colliding with a support to be coated. A second invention is a coating method characterized in that both ends of the coating liquid are supported by an auxiliary liquid which is discharged in a jet shape outward at an angle along the outflow film of the coating liquid. In a device that applies two or more types of coating liquids by colliding with the support to be coated, an auxiliary liquid injection is provided at the tip of the lip of the liquid injection device at an angle outward along the outflow membrane of the coating liquid. This is a coating device characterized by having a hole and provided with a liquid injection means for discharging an auxiliary liquid in a jet form from the liquid injection hole.

In the present invention, the fact that both ends of the "R peritoneal coating solution are angled outwardly along the outflow membrane of the coating solution" means that
Regardless of the tip of each part of the liquid injector or the tip of the edge guide, it is preferable to have an angle outward with respect to the direction in which the thin film-like coating liquid flows out, specifically in the range of t3° to L45°. is preferably in the range of L5° to t20°.

Furthermore, the flow rate of the auxiliary liquid used in the present invention, which is discharged in the form of a jet, varies from 2 m/sec to 50 m/sec depending on the length of the outflow membrane.
Used in the sin range.

Furthermore, as the auxiliary liquid used in the present invention, water is generally used, but in particular, as a liquid that satisfies both the sufficient support of the curtain film and the reduction of the drying load of the coating film, water is used.
For example, alcohol aqueous solutions such as methanol and ethanol, or lower alkyl acetates such as ethyl acetate and butyl acetate, ethyl propionate, secondary butyl alcohol, methyl isobutyl ketone, β-ethoxyethyl acetate, methyl cellosolve acetate, etc. have a boiling point of about 30 Preferably, the solution is a volatile solution such as a low-boiling organic solvent having a temperature of 150°C to 150°C.

It goes without saying that such an auxiliary liquid should not impair the physical properties of the coating liquid used, that is, the quality of the coating film, and therefore should be appropriately selected depending on the type of coating liquid.

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic front view of a curtain coating device showing an embodiment of the present invention, and FIG. 2 is a side view thereof.

In FIGS. 1 and 2, the coating liquid 11, 12, 13 is applied to the slide popper type liquid injector 3 at the pump P1°P2. P3
The liquid is fed into the manifold 8°9.10, passes through the slots 14 and 15.16, and becomes a thin film coating liquid, flows down the slide surface 17, and is sequentially overlapped to form a multilayer thin film coating liquid. The liquid reaches each part 18 of the slide hopper injector 3 and flows vertically down from each part 18 onto the support 2 to be coated to form the curtain film 6.

Auxiliary liquid 5 is supplied from a tank (not shown) to pumps P4a and P4.
b, jets are jetted outward at an angle θ from the auxiliary liquid injection holes 7a and 7b provided at the tip of each part 18 of the slide hopper type liquid injection device 3 along the curtain film 6, which is a falling film of the coating liquid. The left and right sides of the curtain membrane 6 are supported as jet auxiliary liquids 5a and 5b.

Curtain membrane 6 supported on the left and right by jet auxiliary liquids 5a and 5b
is the support to be coated, which is conveyed by a back-up roll l. It is applied by colliding with the web 2.

In this case, the jet auxiliary liquids 5a and 5b play the role of edge guides, are liquids that do not impair the original physical properties of the coating liquid 11, 12, 13 used, and protect the side edges of the curtain film 6. A liquid is used that has sufficient surface tension to hold it. For example, when the coating liquid 1 is an aqueous gelatin solution, a volatile solution such as a methanol aqueous solution is particularly effective as the auxiliary liquid in that it reduces the drying load.

Although the above description is based on one embodiment of the present invention, the present invention is not limited to this embodiment and can be modified as described below.

That is, in the embodiment described above, the free-falling curtain is formed using a slide hopper type liquid injector, but the present invention is not limited to this, and an extrusion type liquid injector disclosed in Japanese Patent Publication No. 51-39264 may be used. You can also do that. Furthermore, the method is not necessarily limited to the curtain coating method, but can also be applied to a method in which a thin film coating liquid is applied by colliding with the web to be coated, as disclosed in Fig. 2 of Japanese Patent Application No. 52-31351. can do.

Furthermore, the number of coating liquids that are allowed to collide with the support is not limited to one type, and two or more types of coating liquids may be supplied in a superimposed relationship.

Although the coating liquid used in the present invention is not particularly limited, it can be particularly suitably used in the production of photographic light-sensitive materials, magnetic recording materials, and pressure-sensitive copying paper.

When the present invention is used in the production of photographic light-sensitive materials, the manufacturing method, composition, necessary additives, web material, various treatments, etc. of the photographic coating solution are described in Japanese Patent Publication No. 49-14130 and Japanese Patent Publication No. 49-241.
All of the materials disclosed in No. 33 and No. 49-35447 can be used. Here, as a coating liquid for photography,
It includes not only light-sensitive ones such as photographic emulsions, but also all kinds of coating liquids used in the production of photographic light-sensitive materials, such as undercoat coating liquids, anti-halation coating liquids, and back-up coating liquids.

When the present invention is used to manufacture magnetic recording materials, the manufacturing method, composition, necessary additives, web material, various treatments, etc. of the coating liquid for magnetic recording materials are disclosed in Japanese Patent Application No. 154491/1982. Everything is available for use. The coating liquid for magnetic recording materials includes all coating liquids used in the production of magnetic recording materials, such as magnetic coating liquids and backcoat coating liquids.

In addition, when the coating method according to the present invention is applied to the production of magnetic recording materials, an orientation device is provided in the thin film portion made of the coating liquid to improve the orientation and the stability of the thin film made of the coating liquid. Although it is necessary to set specific implementation conditions for the magnetic coating liquid and magnetic recording material, all of the conditions disclosed in Japanese Patent Application No. 51-96675 can be used for this purpose.

When the present invention is used to manufacture pressure-sensitive copying paper, the manufacturing method, composition, necessary additives, web material, various treatments, etc. of the pressure-sensitive copying paper liquid are disclosed in Japanese Patent Application No. 76743/1982. Everything provided can be used.

Coating liquid for pressure-sensitive copying paper includes all coating liquids used in the production of pressure-sensitive copying paper, such as coating liquids containing microcapsules as a main component and coating liquids containing a color developer as a main component. It will be done.

Furthermore, if the coating method according to the present invention is to be applied to the production of pressure-sensitive copying paper, it is necessary to set specific implementation conditions for the coating liquid for pressure-sensitive copying paper, but this is disclosed in Japanese Patent Application No. 51-76.
The material disclosed in No. 743 can be used.

[For production]

The present invention provides a method of applying one or more types of coating liquid in the form of an i-film by colliding with a support to be coated, in which both ends of the coating liquid in the form of a thin film are directed outwardly along the outflow film of the coating liquid. By supporting the auxiliary liquid discharged in a jet shape with an angle to the side, the flow velocity at the side edge of the coating liquid outflow membrane is increased, and the direction of the auxiliary liquid is angled outward.
The outflow velocity distribution of the coating liquid outflow membrane is made uniform in the width direction, and the outflow membrane is initially expanded outward, and then contracts to the width of the coating liquid and is applied onto the support.

Therefore, the surface tension distribution is made uniform by the above-mentioned expansion and contraction, and thickly coated areas can be eliminated. Furthermore, even if the curtain film becomes higher, or even if the distance from the tip of the edge guide to the top surface of the application roll is increased (even if the edge guide is removed), the angle and amount of the auxiliary liquid jet should be adjusted according to the height. This can prevent liquid film contraction and local thick coating.

It can also be used to control the coating width on the support by adjusting the angle and jetting amount of the auxiliary liquid.

〔Example〕

Examples will be given to further clarify the effects of the present invention.

Example 1 A comparative experiment between the coating method according to the present invention and a conventional coating method was conducted using a coating liquid having the composition and physical properties shown in Table 1. Coating of 150 cc/% (wet dip state) onto a 100 μm thick, medium 18C11 polyethylene terephthalate film being conveyed at a speed of 200 m/min by the slide Hof bar type curtain coating device shown in Figures 1 and 2. It was applied in quantity.

Here, the height of the curtain film is 20 cm, and the coating width is 15 cm.
Then, an auxiliary liquid injection hole with an inner diameter of 0.17n was inserted at both ends of the thin film-like coating liquid in the outward direction along the falling film of the coating liquid.
It was tilted and installed at the tip of the lip of a slide hopper type Giesser, and water was pumped as an auxiliary liquid from this auxiliary liquid injection hole at a flow rate of 10 cc/min.During the coating operation, a force τ-ten film was applied to the web. When we observed the coating process, we found that the width was the same as the width regulated by the guide plate of the slide hopper type curtain giesser.Also, after the coating film was sufficiently gelled with cold air, it was coated using the usual method. After drying, the thickness was measured using a thickness needle, and as a result, virtually no localized thick coating was observed.

Table 1 Example-2 When an aqueous solution of 50% methanol was used instead of water as the auxiliary liquid in Example-1, the same results as in Example-1 were obtained, and the same results as in Example-1 were obtained. When gelling and drying was performed using the same method as in 1, it was confirmed that the time required for drying the coating film was shortened by an average of 15% compared to the case with water.

Comparative Example In Examples 1 and 2, when the auxiliary liquid was applied by discharging the auxiliary liquid by setting the auxiliary liquid injection holes at both ends of the thin coating liquid in the same direction as the outflow direction of the coating liquid, the width of the curtain film was About 5 Bm flowed in the area in contact with the film, and local thick coating of about 1.3 times the predetermined coating thickness occurred continuously.

〔Effect of the invention〕

The present invention provides a coating method in which one or more coating liquids in the form of a thin film are applied by colliding with a support to be coated, in which both ends of the coating liquid in the form of a thin film are moved in an outward direction along the outflow film of the coating liquid film. By using a method characterized by supporting liquid with an auxiliary liquid discharged in a jet form at an angle to the surface of the coating roll, and a device embodying the method, even when the height of the curtain film is increased, the coating roll can be coated from the tip of the edge guide to the top surface of the coating roll. Even if the distance was increased, the surface tension of the coating solution did not cause contractions and localized thick coatings at both ends.

In addition, it is now possible to form a uniform film and obtain a uniform coating thickness without using the edge guides conventionally used in the curtain coating method, simplifying the process and increasing yield. did it.

In addition, by carrying out the present invention, an edge guide is provided at the start of coating, thereby minimizing the thick coating of parts, and preventing contamination and malfunctions in the process due to undrying. At the same time, it was found that the failures that occurred in the conventional method, where the web was cut due to the joint contacting the edge guide when passing through the joint, were completely eliminated.

[Brief explanation of drawings]

Fig. 1 is a schematic front view of a curtain coating device showing one embodiment of the present invention, Fig. 2 is a schematic side view thereof, Fig. 3 is a cross-sectional view of a coating film produced by a conventional coating method, and Fig. 4 is a schematic front view of a curtain coating device showing an embodiment of the present invention. 5 is a schematic front view of a device that supports both ends of a coating liquid film at the lower end of an edge guide by a liquid jetted out in the same direction as the outflow direction of the coating liquid film, and FIG. 5 is a schematic side view of FIG. 4. . ■... Backup roll 2... Web 3... Slide hopper type pourer 4... Guide plate 5... Auxiliary liquid 5a, 5b... Jet auxiliary liquid 6... Curtain film 7a , 7b... Auxiliary liquid injection hole 8, 9. 10... Manifold 11.12.13... Coating liquid 14.15.16... Slot 17... Slide surface 18... Main part 21... Coating liquid 21C... Curtain film 22. ...Backup rolls 23a, 23b...Edge guide 24...Extrusion type liquid injector 243...Slot 25...Bank up rolls 26a, 26b...Pipe 26ha, 26hb...Auxiliary liquid discharge Exit 27...
Auxiliary liquid (and 3 other people) Figure 1 Figure 2 Figure 3 Figure 4 Procedure 1] Positive (q February 1986)

Claims (4)

[Claims] (1) In a method of applying one or more types of coating liquid in the form of a thin film by colliding with the support to be coated, both ends of the coating liquid in the form of a thin film are directed outward along the outflow film of the coating liquid. A coating method characterized by supporting with an auxiliary liquid discharged in the form of a jet at an angle. (2) The coating method according to claim 1, wherein the auxiliary liquid discharged in a jet form has volatility. (3) In a device that applies one or more types of coating liquid in the form of a thin film by colliding with the support to be coated, the tip of the lip of the liquid injection device is angled outwardly along the outflow film of the coating liquid. 1. A coating device comprising: an auxiliary liquid injection hole having an auxiliary liquid injection hole; and a liquid injection means for discharging the auxiliary liquid in a jet form from the liquid injection hole. (4) The coating according to claim 1, 2 or 3, wherein the angle of the coating liquid in the liquid injection hole in the outward direction along the falling film is ∠5° to ∠20°. Method and apparatus.