JP2003080151A - Coating method and coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new coating method capable of applying a thin layer even at a high speed, and a coating apparatus adapted thereto. SOLUTION: When a liquid coating composition is applied to a web, it is preliminarily applied in a coating amount excessive with respect to a set coating amount and the excessive liquid coating composition is sucked and removed while air is blown against a coating surface to adjust the set coating amount.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a photographic film
Photosensitive materials such as photographic paper and photoengraving materials, magnetic recording materials such as magnetic recording tape, pressure sensitive recording paper, heat sensitive recording paper, etc.
Regarding the improvement of the step of applying a liquid coating composition (hereinafter also referred to as a coating liquid) to a continuous flexible support (hereinafter referred to as “web”) that continuously runs in the production of an inkjet recording sheet, more specifically The present invention relates to a processing device for thinning.

[0002]

2. Description of the Related Art In the coating process as described above, a pre-weighing type coating method using a slide bead, a curtain coater, a slot die, etc., and a post-weighing type coating method in which weighing is performed after excessive coating using a wire bar, a blade, an air knife, etc. The scheme is commonly used. To improve productivity in recent years, coaters have been sped up and coating solutions have been concentrated. Therefore, high-speed, thin-layer coating with a lower coating amount than ever has been required.

However, the pre-weighing type coating method requires a coating amount of at least 40 g / m ² . Further, there has been a limit to the process effort to further reduce the minimum coating amount in the pre-metering coating system. With the post-weighing type coating method, by increasing the speed of the coater and concentrating the coating liquid,
Problems with high-speed / thin layering such as occurrence of coating failure such as bubbles in the coating device and streaks due to sticking of the coating liquid during thinning processing in the post-weighing section, and installation of a removal device due to scattering of the coating liquid. was there.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a novel coating method and coating apparatus capable of performing thin layer coating at high speed.

[0005]

The above objects of the present invention have been achieved by the following coating method and coating apparatus. 1) When the liquid coating composition is applied to the web, the excess coating amount is applied in advance with respect to the set coating amount, and the excess liquid coating composition is sucked and removed while the gas is blown to the coating surface to set the coating amount. It is to provide a coating method characterized by adjusting

2) Using the above coating method, the viscosity is 5 cP.
It is an object of the present invention to provide a coating method characterized by adjusting the following liquid coating composition so that a set coating amount is 30 ml / m ² or less.

3) A liquid coating composition supply device for applying an excess amount of the liquid coating composition to a set coating amount on the web, and the excess amount on the downstream side of the liquid coating composition supply device in the web conveying direction. It is an object of the present invention to provide a coating apparatus having means for sucking and removing an excess liquid coating composition while spraying a gas on the applied liquid coating composition.

4) To provide a coating apparatus characterized in that the liquid coating composition supply apparatus is provided with means for sucking and removing the excess liquid coating composition while spraying the gas. is there.

5) A coating apparatus characterized in that the liquid coating composition supply apparatus and a means for sucking and removing the excess liquid coating composition while spraying the gas are provided separately. To do.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The coating method of the present invention mainly comprises adjusting the coating amount by blowing off the liquid coating composition after overcoating with a gas and sucking. A coating apparatus for carrying out the coating method of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a side sectional view showing an embodiment of the coating apparatus of the present invention. FIG. 2 is a side sectional view showing another embodiment of the coating apparatus of the present invention. FIG. 3 is an enlarged side sectional view of means for sucking and removing the excess liquid coating composition while blowing gas.

In FIG. 1, a coating layer of the liquid coating composition 5 is formed over the entire width of the web 2 which is continuously in contact with the backup roll 1 by the liquid coating composition supply device 3 in an amount more than the set coating amount. To be done. Subsequently, the liquid coating composition 5 excessively applied at a set coating amount by means of a suction nozzle 7 having a gas blowing nozzle 9 for sucking and removing the excess liquid coating composition while blowing gas. The excess coating layer portion of is removed by suction to adjust to the set coating amount 51. The coating apparatus of FIG. 1 is a liquid coating composition supply apparatus 3
A suction nozzle 7 having a gas blowing nozzle 9 is integrally attached to. The suction nozzle 7 having the gas blowing nozzle 9 will be described in detail with reference to FIG.

As the liquid coating composition supplying device 3, a slot die coating device such as an extrusion or fountain is suitable. A decompression device 4 is generally attached to the liquid coating composition supply device 3. In the present invention, the liquid coating composition supply device 3 is also constructed with a suction nozzle 7 attached thereto, and the liquid coating composition supply device 3,
The gaps between the web 2 and the liquid contacting portions of the decompression device 4 and the suction nozzle 7 can be individually adjusted.

In FIG. 2, a coating layer of the liquid coating composition 5 is formed over the entire width of the web 2 which is in continuous contact with the backup roll 1 by the liquid coating composition supply device 3 in an amount more than the set coating amount. To be done. Then, by a suction nozzle 7 having a gas blowing nozzle 9 over the entire width of the web 2 which is in contact with the backup roll 6 and continuously runs,
The excess coating layer portion of the liquid coating composition 5 which is over-coated from the set coating amount is removed by suction to adjust to the set coating amount 51.

As the liquid coating composition supplying device 3, a slot die such as an extrusion or fountain, a dip, or a wire bar coating device is suitable. In FIG. 2, the continuously running web is over-coated with the liquid coating composition supply device 3 by the backup roll 1, and then the over-coated part is sucked and removed by the suction nozzle 7 having the gas spray nozzle 9 by the backup roll 6. However, the present invention is not limited to this and the liquid coating composition supply device 3 and the suction nozzle 7 may be arranged on the backup roll 1.

In FIG. 3, the web 2 running continuously.
Over the entire width thereof, a coating layer of the liquid coating composition 5 over-coated with the set coating amount is formed, and the suction nozzle 7 according to the present invention attached to the entire width direction of the web 2 sucks and removes the excess coating portion. Then, the set coating amount 51 is adjusted. A blowing nozzle 9 for blowing gas toward the web 2 is attached to the tip of the suction nozzle 7 with an inclination angle θ with respect to the web 2. A part of the liquid coating composition 5 excessively coated with respect to the set coating amount is peeled off from the web 2 by the blowing nozzle 9 that blows out gas toward the web 2, and is sucked from the tip of the suction nozzle 8 to set. Application amount 51
Adjusted to. The sucked liquid coating composition is discharged from a pipe attached above the suction nozzle 8 by an exhaust device (not shown).

In FIG. 3, the tips of the suction nozzle 8 and the blow-out nozzle 9 for blowing out the gas are separated from the web 2 by a distance A from the web 2 so as not to directly hit the web 2 and the liquid coating composition 5 which is over-coated with the set coating amount. Is installed in. The distance A needs to be slightly changed depending on the coating amount of the liquid coating composition 5, but is about 0.2 mm to 2 mm, more preferably 0.3 mm.
mm to 1 mm is preferable.

The blowing nozzle 9 for blowing the gas is preferably mounted so as to be blown in the direction opposite to the web traveling direction 10. Angle θ between blowing nozzle 9 and web 2
Is 10 when the suction nozzle 7 with respect to the web 2 is vertical.
The angle is about 70 ° to 70 °, more preferably 20 ° to 60 °. The suction nozzle 7 is 60 ° to 10 ° with respect to the web 2.
It is preferably about 0 °, more preferably 70 ° to 90 °. The viscosity of the coating liquid is 5 cp or less, preferably 3 cp or less,
It is suitable when the wet coating amount is 30 ml / m ² or less.

[0018]

EXAMPLES Examples will be given below to clarify the effects of the present invention. However, the present invention is not limited to the examples described below.

As the support, a polyethylene resin-coated paper coated with a silver halide emulsion and dried is used.
A coating solution containing physical development nuclei was applied. The width of the support is 1500 mm and the coating width is 1490 mm. The coating speed is 250 m / min. Set application amount is 10, 20, 30 ml
/ M ² . Viscosity is 5 cP.

Example 1 The coating apparatus of the present invention used the coating apparatus shown in FIG. 2 in which the liquid coating composition supplying apparatus 3 and the suction nozzle 7 are separately installed.

Comparative Example 1 As a comparative example, a coating apparatus comprising a fountain nozzle and an air knife shown in FIG. 4 was used. A fountain nozzle 31 forms a coating layer of the liquid coating composition 5 over-coated over the entire width of the continuously running web 2 by a fountain nozzle 31 and is scraped off by an air knife 21 to adjust to a set coating amount 51. It is a device.

The experimental results are shown in Table 1. In addition, ○ in Table 1
Indicates uniform application without application failure, × indicates occurrence of bubble or streak failure. According to the present invention, it can be seen that excellent coating properties, which have not been obtained in the past, are exhibited in the high speed and thin layer regions. In the conventional method such as the comparative example, a coating failure such as bubbles or streaks occurs when the excessive coating portion is scraped off, and a clean coating surface cannot be obtained. Therefore,
It was confirmed that it is preferable to use the coating apparatus of the present invention.

[0023]

[Table 1]

[0024]

As is clear from the above, by the method of suction removal of the liquid coating composition according to the present invention, high speed coating /
It enables thin layer coating and improves productivity and quality.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a coating apparatus of the present invention.

FIG. 2 is a side sectional view showing another aspect of the coating apparatus of the present invention.

FIG. 3 is an enlarged side cross-sectional view of means for sucking and removing the excess liquid coating composition while blowing gas.

FIG. 4 is a side cross-sectional view of a conventional coating apparatus including a fountain nozzle and an air knife.

[Explanation of symbols]

1 backup roll 2 web 3 Liquid coating composition supply device 4 decompression device 5 Liquid coating composition 6 backup roll 8 suction nozzles 9 blowing nozzle 10 Web traveling direction 51 Set coating amount θ Inclination angle of the blowing nozzle with respect to the web

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B41M 5/00 B41M 5/00 B 4F042 5/26 G03C 1/74 5D112 G03C 1/74 G11B 5/84 Z G11B 5/84 B41M 5/18 B F term (reference) 2H023 EA00 EA01 2H026 AA07 HH05 2H086 BA02 BA15 4D075 AC04 AC59 AC60 AC84 AC92 BB57Z CA47 DA04 DC27 EA45 4F041 AA12 AB02 BA51 BA15 CC11 BA22 BA31 BA12 BA09 4F042 GA25

Claims (5)

[Claims] 1. When applying a liquid coating composition to a web, an excess coating amount is applied in advance with respect to a set coating amount, and a surplus liquid coating composition is removed by suction while blowing a gas onto a coating surface, A coating method characterized by adjusting to a set coating amount. 2. The coating method according to claim 1, wherein a liquid coating composition having a viscosity of 5 cP or less is adjusted so that a set coating amount is 30 ml / m ² or less. 3. A liquid coating composition supply device for applying an excessive amount of a liquid coating composition to a web with respect to a set coating amount, and the excess amount on the downstream side of the liquid coating composition supply device in the web conveying direction. A coating apparatus comprising means for sucking and removing excess liquid coating composition while spraying gas onto the coated liquid coating composition. 4. The coating apparatus according to claim 3, wherein the liquid coating composition supply apparatus is provided with means for sucking and removing the excess liquid coating composition while blowing the gas. 5. The coating apparatus according to claim 3, wherein the liquid coating composition supply apparatus and a means for sucking and removing the excess liquid coating composition while spraying the gas are separately installed.