JPH0615211A - Coating device - Google Patents

Abstract

PURPOSE:To stabilize a sliding bead so that an application fault is prevented from occurring by roughing the surface of a sliding face of a sliding bead coating device to a specified degree of roughness in the device which applies at least, more than a single layer of coating liquid to a continuously running support. CONSTITUTION:A sliding bead coating device designed for concurrent two-layer coat application allows coating liquids 13 of different kinds to a sliding surface 16 through a pocket 14 and a slot 15 which spread in a width direction, then reach the tip 17 of the coating device flowing down on the sliding surface 16, and finally to be applied to the surface of a web 12 which runs with a packing roll 10 through a bead (reservoir) 18. In this case, the sliding surface is roughed so that its surface roughness (average roughness of the center line) is >=0.5mum. In addition, this sliding surface is treated using a coating agent with high energy surface (the contact angle of <=40 deg. <=30 deg. and <=60 deg. with methylene iodide, ethylene glycol and distilled water, respectively).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slide bead coating device, and more particularly to improvement of coating properties.

[0002]

BACKGROUND OF THE INVENTION A slide bead coating device is capable of high speed, thin film and multi-layer simultaneous coating, and is widely used as a coating device for photographic light-sensitive materials and magnetic recording materials due to its characteristics. In this type of coating apparatus, the coating solution flows down a slide surface through a slit that extends in the width direction called a slot in the coating machine, and is fed at the tip of the coating machine (also simply referred to as edge or lip). A coating liquid reservoir called a bead is formed between the bead and the web (also called a web), and coating is performed through the bead.

In such a so-called bead coater, the stability of the beads greatly affects the stability of the coating. The stability of the bead depends on the setting of the gap between the lip and the web, the environmental conditions, the physical properties of the coating liquid, that is, the viscosity, and the surface tension. As the film thickness decreases, it becomes difficult to stabilize the beads. If the bead is unstable, a failure such as a muscle failure, a tailing failure, or a liquid shortage may occur.

In order to improve the stability of the beads, for example, a method is known in which a pressure difference is provided above and below the beads. Specifically, measures are taken such as providing a decompression chamber below the bead and pulling the bead downward to improve the stability of the bead.

Further, in order to stabilize the beads, wetting of the coating liquid and the coating device is also an important problem. As described above, the coating liquid flows down the slide surface to the tip and forms a bead between the web and the coating liquid. It becomes stable, and the wetting at the tip portion hinders the formation of the bead portion in the width direction.

In addition, when the wetness of the slide surface is not sufficient even on the actual work surface, the so-called water leader must be used to wet the slide surface in advance to improve the wettability at the beginning of the application. Come on.

Such a problem of wetting is also present in the vertical surface which contacts the bead of the coating apparatus, and in this case, rather good wetting hinders good bead formation. That is, in such a case, if the wetness is good, the coating liquid may seep out of the lip portion other than the bead and drop onto the coating film or the support to cause tailing failure or liquid dripping. Become.

[0008] For such a problem, for example,
1-57629 proposes a method of applying a water-repellent resin to the lip portion at the tip of the coating device, and Japanese Patent Application No. 4-9357 proposes a method of forming a composite plating film with a fluorine-containing resin. These are not yet fully resolved because of problems such as accuracy and scratches.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a coating apparatus capable of reducing coating failures by stabilizing beads in the slide bead coating and enabling stable coating. is there. Another object of the present invention is to provide a coating apparatus that enables stable coating without operations such as a water leader and leveling.

[0010]

The above object of the present invention is to provide a method of applying a coating solution to at least one layer on a continuously running support by using a slide bead coating device, wherein the surface of the sliding surface of the coating device is Roughness (centerline average roughness) is 0.5 μm
The coating device characterized by being roughened as described above or the sliding surface of the coating device has a high energy surface (contact angle to methylene iodide is 40 ° or less, contact angle to ethylene glycol is 30 ° or less, distilled water The contact angle with
A coating device having a surface of 60 ° or less), and / or a surface with a vertical surface roughness (center line average roughness) of 0.2 μm or less on the vertical surface of the coating device. It is achieved by a coating device characterized by being smoothed.

The present invention will be specifically described below.

FIG. 1 is a sectional view showing an example of a slide bead coating apparatus, which is a coating apparatus capable of simultaneously coating two layers. In the figure, a plurality of coating liquids 13 pass through a pocket 14 and a slot 15 extending in the width direction to reach a slide surface 16, and the coating liquid flows down the slide surface to reach a tip (also referred to as an edge or lip) 17 of a coating machine. Here, it is applied onto the running web 12 which is held by the backing roll 10 via a liquid pool called a bead 18.

The present invention is directed to the slide surface 16 and the vertical plane from the edge in such a slide bead coating apparatus.
The stability of coating property is enhanced by changing the surface property of 19.

The center line average roughness (Ra) referred to in the present invention is
It is based on the method described in Japanese Industrial Standard JIS B-0601.

In the present invention, the Ra value needs to be 0.5 μmm or more over the entire slide surface. Thereby, the wettability required for the slide surface of the coating liquid can be secured.

In the present invention, the fact that the slide surface is a high-energy surface means that the surface is well wetted by a non-polar solvent such as oil or a polar solvent such as water, and specifically, a contact angle with respect to methylene iodide. Is 40 ° or less, the contact angle with ethylene glycol is 30 ° or less, and the contact angle with distilled water is 60 ° or less.

Specific examples of the coating agent having such a high energy surface include glass coating and ceramic coating. As the glass coating, a coating method such as glass lining used for enameled can be used. Various methods have been announced for ceramic coating. For example, it is described in Industrial Materials, Vol. 30, p. 18 to p. 26, "Low Temperature Firing Ceramic Coating Agent". In the present invention, the dry plating method is preferable, but not limited to this.

By thus changing the surface property of the slide surface and improving the wettability of the coating liquid with respect to the slide surface, liquid separation does not occur on the slide surface even if the coating speed is increased, and a water reader is used beforehand. The wettability can be secured without any work such as improving the wettability of the metal surface.

Next, in the present invention, the vertical surface of the coating device in contact with the bead is made into a smooth surface having a center line average roughness of 0.2 μm or less by surface smoothing processing such as buffing and lapping.

As a result, the wettability of the vertical surface with respect to the coating solution is lowered, and the coating solution oozes out of the lip portion other than the bead due to good wetting and falls onto the coating film or the support. It is possible to avoid problems such as tailing failure and liquid dripping.

[0021]

EXAMPLES Hereinafter, the effects of the present invention will be specifically illustrated by examples.

Example 1 Coating liquid conditions Lower layer Gelatin silver halide emulsion layer Viscosity 10 cp (35
℃) Top layer containing surfactant and other usual additives Gelatin protective film layer Viscosity 12cp (35
(° C) Surfactant and other usual additives are used. Subbing layer coated with polyethylene terephthalate base Coating conditions Coating speed 120m / min wet thickness Upper layer: 20μm Lower layer: 50μm Coating device Slide bead coating device in Figure 1 A comparison was made between the roughened surface and the non-surfaced surface.

In this case, the contact angle is 23 ° for the rough surface and 68 ° for the non-rough surface, and it can be seen from the contact angle that the wettability is improved by the roughening.

Coating Results In the case of roughening, streak failure and lateral unevenness were reduced, and good coating properties were exhibited. Further, in coating, the coating liquid was directly supplied without using a water leader, but the coating liquid spreads evenly on the slide surface, and there was no need for surface leveling (work to help wet the coating liquid). Example 2 Using the same coating liquid and coating conditions as in Example 1, coating was performed when the slide surface of the coating device was set to the following conditions.

Sliding surface conditions A comparison was made between ceramic (alumina) vapor deposition and non-ceramic vapor deposition.

In this case, the contact angle is determined by ceramic vapor deposition 12
No, surface 68 ° Application result Similar results to Example 1 could be obtained.

Example 3 The sliding surface conditions were set as follows in the same manner as in Example 2.

Sliding surface conditions Comparison was made between glass coated and non-glass coated.

In this case, the contact angle was 0 ° on the glass-coated surface and 68 ° on the non-coated surface. Application result Similar to Examples 1 and 2, when a glass-coated slide surface was used, good results could be obtained.

Example 4 Under the same coating solution conditions and coating conditions as in Example 2, the conditions for the vertical plane of the coating apparatus were as follows.

Vertical Surface Conditions A comparison was made between the surface with vertical surfaces and the surface without lapping.

Surface roughness Lapping treatment 0.2 μm, contact angle 116 ° Non-lapping treatment 0.4 μm, contact angle 68 ° Application result There is no streak failure when lapping the vertical surface and good application result. I was able to get it.

[0033]

According to the present invention, in slide bead coating, coating failure is reduced by stabilizing the bead,
It has been possible to provide a coating device that enables stable coating, and further it is possible to provide a coating device that enables stable coating without operations such as a water leader and leveling.

[Brief description of drawings]

FIG. 1 is a sectional view of a slide bead coating device.

[Explanation of symbols]

 12 Web 16 Slide surface 18 Bead 19 Vertical surface

Claims (3)

[Claims] 1. A method of applying a coating solution to at least one layer using a slide bead coating device on a continuously traveling support, wherein the surface roughness (center line average roughness) of the sliding surface of the coating device is used. Is roughened to 0.5 μm or more. 2. A method of applying a coating solution to at least one layer on a continuously traveling support using a slide bead coating device, wherein the slide surface of the coating device is a high energy surface (to methylene iodide). A coating device having a contact angle of 40 ° or less, a contact angle with ethylene glycol of 30 ° or less, and a contact angle with distilled water of 60 ° or less). 3. A method of applying a coating solution to at least one layer on a continuously running support by using a slide bead coating device, wherein the surface roughness of the vertical surface of the coating device (center line average roughness) is used. Is a surface smoothing treatment of 0.2 μm or less.