JP3191166B2 - Application method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of coating stability by a slide hopper coating machine.

[0002]

BACKGROUND OF THE INVENTION A slide hopper coating machine is characterized by being capable of multi-layer simultaneous coating, and is therefore widely used especially for coating requiring high speed and thin film coating such as a silver halide photographic light-sensitive material. .

FIG. 1 is a sectional view showing the structure of an example of such a slide hopper coating machine.

FIG. 1 shows two layers. For example, when a protective layer is coated simultaneously with an emulsion layer of a light-sensitive material, an emulsion 9a and a protective film 9b are fed from a slot 4 to a slide surface 5 through a pipe. These liquids flow down in an overlapping manner to reach the coating machine lip 6. Here, the emulsion layer and the protective layer are simultaneously coated on the web while forming a liquid pool called a bead 13 between the web and the web 7 which is a long support that runs while being held by the coating backup roll 1.

[0005] Such a coating method is generally called slide bead coating, and the stability of the bead has a very large effect for stable coating. If the bead is not stable, a vertical streak failure or the like may occur, and in severe cases, the coating solution may run out.

For this reason, a method of providing a pressure difference above and below the bead is used. Specifically, it is a method of stabilizing the bead by pulling the bead downward by decompression as in the decompression device 3 of FIG.

Various factors are involved in stabilizing a bead. For example, the accuracy of the gap between the web and the lip portion (also referred to as bead gap), the physical properties of the coating liquid, especially in the case of simultaneous application of a plurality of coating liquids, the relationship between the mutual physical properties, the precision of pressure reduction, and the like.

[0008] For coaters, stabilization of the bead gap is particularly important. Recently, the necessity of improving productivity has tended to widen the coating width, and it has been a very difficult problem to maintain accuracy over the entire coating width.

It is needless to say that the accuracy of manufacturing the coating machine is important for stabilizing the bead gap, but the maintenance of the coating machine also has a great effect.

In the case of coating a light-sensitive material, generally, a sol-like coating layer applied to perform coating by utilizing a sol-gel change of gelatin is immediately exposed to a cool air called a set, and this is exposed to the surroundings of the coating machine. It also has some influence on the environmental temperature. For this reason, special attention must be paid to the temperature control of the coating machine.

Conventionally, warm water is circulated in the coating machine to keep the temperature, but at present it is not enough to maintain the bead gap accuracy.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the gap accuracy of a bead in a slide hopper coating and to provide a coating method with improved coating accuracy and a stable coating method.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a slide bead coating apparatus for applying a coating liquid to a continuously running web by a slide hopper coating machine. The material constituting the chamber is the same as the slide hopper body,
It is also achieved by a coating method characterized by keeping the gantry warm. Hereinafter, the present invention will be described specifically.

As a specific example of coating by a slide hopper coating machine, coating of a silver halide photographic light-sensitive material is given.
Coating speed of 100 m / min or more, coating width of 150 cm or more, and simultaneous coating of 6 layers or more are possible. Examples of conditions in this case are, for example, when the wet film thickness of one layer is about 20 μm and the bead gap is about 150 μm There is. As can be seen from this example, the coating is fairly precise, and therefore, very high bead gap accuracy is required.

For this reason, in the temperature maintenance management, it is desired to improve the accuracy of the heat retaining temperature by any means.

The decompression chamber is usually fixed to the slide hopper body via bolts and the like. When applying a coating liquid higher than room temperature, the decompression chamber itself thermally expands due to heat conduction from the slide hopper body. It has been found that if both are made of the same material, the change in the bead gap in long-time long coating can be suppressed by making the linear expansion coefficients uniform.

The material of the gantry is preferably the same as that of the slide hopper body for the same reason.

In addition, the frame of the slide hopper was not particularly kept warm in the past, but it has been found that the temperature of the frame is also effectively kept for the above-mentioned highly accurate temperature control.

A heat retaining pipe 12 is provided in a slide hopper base 11 shown in FIG. The gantry 11 is a set of two units and is supported at two points at symmetric positions in the width direction of the slide hopper. The way of the pedestal heat retaining pipe is not limited to the method of FIG.

In FIG. 1, reference numeral 10 denotes a heat retaining pipe of the slide hopper body.

[0021]

EXAMPLES The effects of the present invention will now be illustrated by examples.

Example 1 A slide hopper type coating machine shown in FIG. 1 for three layers was used.

(Layer Structure) A high-sensitivity green-sensitive emulsion layer Em1, a low-sensitivity green-sensitive emulsion layer Em2, and a protective layer were coated in this order from the side closer to the web. Emulsions are used for ordinary color light-sensitive materials and contain magenta couplers.

The web used was a web in which a red-sensitive photosensitive layer containing a cyan coupler was coated on a triacetyl cellulose base.

(Coating conditions) Coating speed: 100 m / min, Coater decompression 30 mmaq, Coater gap 150 μm Em 1 layer Wet thickness 20 μm, Viscosity 10 cp Em 2 layer Wet thickness 30 μm, Viscosity 15 cp Protective layer Wet thickness 20 μm, Viscosity 18 cp It measured at 38 degreeC with the field viscometer.

The application temperature of the slide hopper is 38 ° C.
Water was passed through.

(Materials of Coating Machine) Two types of slide hopper bodies and decompression chambers having the following different materials were prepared. (1) 18Cr-8Ni chromium nickel steel (linear expansion coefficient 16.
(7 × 10 ^-6 / ℃) (2) 25Cr-20Ni chromium nickel steel (linear expansion coefficient 14.
4 × 10 ^-6 / ° C) Combine the slide hopper body and the decompression chamber with the above two materials, apply for about 20 hours with the above layer structure, and check the number of longitudinal streak coating failures from the beads over time. It was measured. From the above results, in Nos. 1 and 4 where the same material was used for the slide hopper body and the decompression chamber, No. 1 where different materials were used.
The frequency of occurrence of muscles is extremely low as compared with the cases of 2 and 3, and this tendency is remarkable over time.

Example 2 A slide hopper type coating machine shown in FIG. 1 for three layers was used.

(Layer Structure) A high-sensitivity blue-sensitive emulsion layer Em3, a low-sensitivity blue-sensitive emulsion layer Em4, and a protective layer were coated in this order from the side closer to the web. Emulsions are used for ordinary color light-sensitive materials and contain a yellow coupler.

The web used was one coated with a red-sensitive emulsion layer containing a cyan coupler and a green-sensitive emulsion layer containing a magenta coupler on a triacetyl cellulose base.

(Coating conditions) Coating speed: 80 m / min, Coater decompression 30 mmaq, Coater gap 150 μm Em 3 layers Wet thickness 20 μm, viscosity 10 cp Em 4 layers Wet thickness 30 μm, viscosity 15 cp Protective layer Wet thickness 30 μm, viscosity 18 cp However, the viscosity is Brook It measured at 38 degreeC with the field viscometer.

The application temperature of the slide hopper is 38 ° C.
Water was passed through.

(Materials of Coating Machine) Two types of slide hopper bodies and decompression chambers having different materials (1) and (2) were prepared. Further, the coating machine stand was combined with the presence or absence of heat keeping at 38 ° C. by the method of FIG.
The number of occurrences of longitudinal streak failures was measured in the same manner as described above. The results are shown below.

No. 5 6 7 8 9 10 11 12 Main unit (1) (2) (1) (2) (1) (2) (1) (2) Decompression chamber (1) (1) (1) ( 1) (2) (2) (2) (2) Heat insulation of gantry Yes Yes No No Yes Yes No No Time (hours) 0 0 0 0 0 0 0 0 0 5 0 0 5 6 0 0 7 4 10 0 0 10 9 0 0 11 12 15 0 1 17 16 0 0 15 18 20 0 1 20 18 1 0 19 23 Based on the above results, the materials of the main body and the decompression chamber are the same as No. 5 and 10, and the stand is kept warm. In this case, the results were extremely excellent. After that, although the materials were different as in Nos. 6 and 9, the effect of maintaining the gantry was excellent. On the other hand, even if the material is the same or different, No. 7,
8, 11, and 12 are inferior.

[0035]

According to the present invention, in the slide hopper coating, the bead gap accuracy can be improved, and the coating accuracy can be improved and a stable coating method can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration sectional view of a slide hopper coating machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Application backup roll 2 Slide hopper main body 3 Decompression chamber 4 Slot 5 Slide surface 6 Lip part 7 Web 9 Coating liquid 9a Emulsion liquid 9b Protective film liquid 10 Slide hopper main body heat-retaining pipe 11 Slide hopper gantry 12 Heat insulation tubing 13 Bead

Claims (2)

(57) [Claims] In a slide bead application for applying a coating liquid to a continuously running web by a slide hopper coating machine, a material constituting a decompression chamber for maintaining a bead is the same as that of the slide hopper body. Coating method. 2. A slide base for supporting a slide hopper main body in a slide bead coating for applying a coating liquid to a continuously running web by a slide hopper coating machine .
A coating material which is the same as the material of the slide hopper body .