JPH10115890A - Curtain coating application method of photographic sensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a coating application threshold speed by specifying the coating liquid flow rate per coating application width unit length of a curtain of a free falling liquid film and executing coating application while adjusting the surface of a web to a specific temp. SOLUTION: The coating liquid is made to collide, as a free falling liquid film (curtain 5), against the surface of the continuously traveling web 3 and is applied on the web 3. At this time, the flow down rate of the coating liquid per coating application width unit length of the curtain 5 of the coating liquid is set in a range of 2.5 to 10cc/cm/sec and the coating liquid is applied on the web 3 by regulating the temp. of the surface of the web 3 to 22 to 55 deg.C. As a result, the uniform coating film may be formed without the occurrence of liquid sagging of the coating liquid and the coating application threshold speed may be improved. Static electricity is impressed on the surface of the web 3 and the surface potential of the web at the time of coating application is set at 0.1 to 0.8KV, by which the adhesive power of the coating liquid on the web surface is promoted under the electrostatic attraction by the electrostatic field acting thereon, thereby, the further stable coating application is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention particularly relates to the production of a photographic film, a photographic printing paper and the like, in which a coating solution such as a photographic emulsion is uniformly coated on a continuously running belt-shaped support (hereinafter referred to as "web"). The present invention relates to a method for producing a photographic material by curtain coating.

[0002]

2. Description of the Related Art Curtain coating technology has been conventionally applied in the production of photographic films, photographic printing papers, and the like. The basic technology of curtain coating is described, for example, in Japanese Patent Publication No. 49-24133, It is described in each gazette of JP-A-49-35447. Also, SFKistler said, "AlChE Winter Na
National Meeting "(1982) discloses the theory of curtain coating. In particular, the following three phenomena are mainly described as phenomena that control the coating speed by the curtain coating method.

[0003] (1) A phenomenon in which microbubbles are trapped between a web and a coating liquid (hereinafter referred to as an "air entrainment phenomenon"). (2) A phenomenon in which a liquid pool is generated at a contact line between the web and the coating liquid (hereinafter referred to as a "heel phenomenon"). (Especially occurring when a high coating liquid flows down) (3) A phenomenon in which the coating liquid does not adhere to the web and flies off (hereinafter referred to as "drip phenomenon", which occurs when the high coating liquid flows down as in (2) above). As an attempt to improve the coating speed limit of the curtain coating, for example, a method of applying an electrostatic field between the web and the coating liquid to increase the adhesion of the coating liquid and suppress the air entrainment phenomenon (Japanese Patent Laid-Open No. 62-197176) See, for example).

However, in recent years, the coating speed has been increased to 250 m /
As the flow rate of the coating liquid has become higher than a minute and the flow rate of the coating liquid flowing down the curtain has been increased, the problem of suppressing the coating speed by the “drip phenomenon” rather than the “air entrainment phenomenon” has become a problem. As a countermeasure, a method of suppressing the heel phenomenon by adjusting the shear viscosity of the lower layer and the upper layer of the coating liquid (Japanese Patent Laid-Open No.
No. 131549). In slide bead coating, heat treatment of the surface of the support eliminates troubles at the start of coating and enables high-speed coating and thin-layer coating. No. 61-278848.

[0005]

However, the technology described in the above-mentioned Japanese Patent Application Laid-Open No. 61-278848 does not significantly affect the coating flow rate, but the application limit is a slide bead coating in which the coating limit is an air entrainment phenomenon. In the present situation, no study has been made on the effect of suppressing the heel phenomenon and the dripping phenomenon, which are the phenomena peculiar to the curtain coating which is the object of the present invention, which is a technique relating to the stability of coating.

An object of the present invention is to cause a dripping phenomenon of a coating liquid particularly in a flow rate range of a high coating liquid flowing amount of 2.5 to 10 cc / cm / sec per unit length of a curtain coating width. It is an object of the present invention to provide a curtain coating method capable of forming a uniform coating film without any problem and improving a coating limit speed.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that under a specific condition in a specific flow rate range of a coating solution, a uniform coating film can be formed without causing a dripping phenomenon of the coating solution. Was formed, and it was found that the coating limit speed could be improved. That is, the present invention provides a curtain coating method for a photographic light-sensitive material, in which a coating liquid collides with a surface of a continuously running web as a free-falling liquid film and is applied to the coating liquid, wherein a coating width unit of the curtain of the free-falling liquid film is used. A flow rate of the coating solution per length is set in a range of 2.5 to 10 cc / cm / sec, and the temperature of the surface of the web is adjusted from 22 ° C. to 55 ° C. for coating. This is a curtain coating method.

In a preferred embodiment of the present invention, the photographic photosensitive material can be produced by applying static electricity to the web surface before or during coating in the curtain coating method.

From the standpoint of improving the coating speed limit, it is desirable that the temperature be high. However, in the production of photographic light-sensitive materials, the coated film usually needs to be cooled immediately after coating and gelled. Therefore, if the temperature is too high, the gelation of the coating film will be poor, so that the above temperature is the optimal temperature in the range of the coating liquid flowing down, and as a result, the dripping phenomenon can be effectively prevented. Seem. Also, by applying static electricity to the web surface and setting the web surface potential at the time of coating to 0.1 to 0.8 KV, the adhesion of the coating liquid to the web surface is promoted by the electrostatic attraction due to the applied electrostatic field. , Stable application becomes possible.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The coating method of the present invention will be described below with reference to the embodiment shown in FIG. The coating head 1 shown in FIG. 2 has a plurality of slits 4 communicating with each of the liquid reservoirs. The coating liquid discharged from the slits 4 slides on a slide hopper 7 and falls, thereby forming a coating liquid. The curtain 5 is formed. The curtain 5 falls and collides with a landing point 6 on the surface of the web 3 supported by the backup roll 2 and traveling at high speed (in the direction of arrow A), and the coating film 8 is formed.
Is formed. The distance between the liquid film landing point 6 of the curtain 5 and the lip (tip portion) of the slide hopper 7 is, for example, 100 mm.
And the angle α formed by the landing point 6 on the web 3 with respect to the horizontal is not particularly limited,
For example, it can be set to about 60 degrees. The present invention can be implemented using the device configured as described above. That is, as shown in FIG. 2, the coating liquid is caused to collide with the surface of the continuously running web 3 as a free-falling liquid film (curtain 5), and the coating liquid is applied onto the web 3. At this time, the flow rate of the coating liquid per unit length of the coating width of the curtain 5 is set in the range of 2.5 to 10 cc / cm / sec, and the temperature of the surface of the web 3 to which the coating liquid is to be applied is from 22 ° C. 55
Adjust to ° C and apply. Further, as a more preferred embodiment of the present invention, the web 3 is applied before or at the time of application.
It is advisable to apply static electricity to the surface of. By performing curtain coating under these conditions, a uniform coating film could be formed without causing a dripping phenomenon of the coating liquid, and the coating limit speed could be improved. Also, by applying static electricity to the web surface and setting the web surface potential at the time of coating to 0.1 to 0.8 KV, the adhesion of the coating liquid to the web surface is promoted by the electrostatic attraction due to the applied electrostatic field. And further stable coating became possible.

As a method of setting the surface temperature of the web 3 within the above range, a heat treatment may be performed before coating, or a surrounding environmental temperature may be adjusted to adjust the surface temperature of the web 3. . As a method of heat treatment of the web 3 in the present invention, a heating zone is appropriately provided in a transporting path of the support prior to coating, and hot air heated to a predetermined temperature is blown on the running web 3 to heat the web surface. how to,
Alternatively, a method of providing an infrared heating zone or a microwave oven, and radiating or dielectrically heating the web through the web 3 may be used. In addition, heating may be performed by heat transfer via a transport roller that contacts the web 3. Alternatively, various heating methods such as a method of heating through hot air or steam can be employed alone or in combination.

Further, as a method of applying static electricity to the surface of the web 3, a method of applying a high DC voltage to a discharge electrode to give a unipolar charge to the web surface by corona discharge, or a method of applying a static charge to the backup roller 2. Although there is a method by applying a DC voltage, the present invention is not limited to this, and various methods can be adopted.

[0013]

EXAMPLES According to examples in which the coating method of the present invention was carried out,
The effect of the present invention can be made clearer. Various photographic constituent layers were curtain-coated on an undercoated polyethylene-coated baryta paper to produce a multilayer color photographic paper having the following constitution. The coating step in the present invention was performed using the apparatus shown in FIG. The composition of each layer is shown below, and the numbers represent the coating amount (g / m ² ). The silver halide emulsion shows a coating amount in terms of silver.

(Layer Structure) The composition of each layer is shown below. The numbers represent the coating amount (g / m ² ). The silver halide emulsion represents a coating amount in terms of silver. First layer (blue-sensitive emulsion layer) Silver chlorobromide emulsion (cubic, average particle size 0.79, silver bromide 0.3 mol%) 0.27 gelatin 1.22 yellow coupler (ExY) 0.79 color image stabilizer (Cpd) -1) 0.08 Color image stabilizer (Cpd-2) 0.04 Color image stabilizer (Cpd-3) 0.08 Color image stabilizer (Cpd-5) 0.01 Solvent (Solv-1) 0.0. 13 Solvent (Solv-5) 0.13

Second layer (color mixture preventing layer) Gelatin 0.90 Color mixture inhibitor (Cpd-4) 0.08 Solvent (Solv-1) 0.10 Solvent (Solv-2) 0.15 Solvent (Solv-3) 0.12 Color image stabilizer (Cpd-7) 0.12 Solvent (Solv-8) 0.03

Third layer (green-sensitive emulsion layer) Silver chlorobromide emulsion (cubic, average particle size 0.79, silver bromide 0.3 mol%) 0.13 gelatin 1.45 magenta coupler (ExM) 0.16 ultraviolet absorber (UV-2) 0.16 Color image stabilizer (Cpd-2) 0.03 Color image stabilizer (Cpd-4) 0.03 Color image stabilizer (Cpd-5) 0.10 Color image stabilizer (Cpd) -6) 0.01 Color image stabilizer (Cpd-7) 0.08 Color image stabilizer (Cpd-8) 0.01 Color image stabilizer (Cpd-10) 0.02 Color image stabilizer (Cpd-16) ) 0.02 Solvent (Solv-3) 0.13 Solvent (Solv-4) 0.39 Solvent (Solv-6) 0.26

Fourth layer (color mixture preventing layer) Gelatin 0.68 Color mixture inhibitor (Cpd-4) 0.06 Solvent (Solv-1) 0.07 Solvent (Solv-2) 0.11 Solvent (Solv-3) 0.09 Color image stabilizer (Cpd-7) 0.09 Solvent (Solv-8) 0.02

Fifth layer (red-sensitive emulsion layer) Silver chlorobromide emulsion (cubic, average grain size 0.43 μm, silver bromide 0.8 mol%) 0.18 gelatin 0.80 cyan coupler (ExC) 0.33 ultraviolet absorption Agent (UV-2) 0.18 Color image stabilizer (Cpd-1) 0.33 Color image stabilizer (Cpd-2) 0.03 Color image stabilizer (Cpd-6) 0.01 Color image stabilizer ( Cpd-8) 0.01 Color image stabilizer (Cpd-9) 0.02 Color image stabilizer (Cpd-10) 0.01 Color image stabilizer (Cpd-15) 0.04 Solvent (Solv-1) 0 .01 Solvent (Solv-7) 0.22

Sixth layer (ultraviolet absorbing layer) Gelatin 0.48 Ultraviolet absorbing agent (UV-1) 0.38 Color image stabilizer (Cpd-5) 0.01 Color image stabilizer (Cpd-7) 0.05 Solvent (Solv-10) 0.03 Solvent (Solv-9) 0.03 Stabilizer (Cpd-14) 0.03

Seventh layer (protective layer) Gelatin 0.90 Acrylic modified copolymer of polyvinyl alcohol (degree of modification 17%) 0.05 Liquid paraffin 0.02 Color image stabilizer (Cpd-11) 0.01

[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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[0026]

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The flow rate of the coating solution per unit width of the free-falling coating solution film is q = q without changing the coating amount of the composition of each layer.
3,4,5,6 [cc / m / s] was prepared by adding water, sodium polystyrene sulfonate was added as a thickener, and the viscosity of the lowermost layer was 20 cp (shear rate 10 [1 / se].
c]), the other layers have an average viscosity of 50 cp (shear rate 10 [1
/ sec]). The distance between the lip of the slide hopper for curtain coating and the liquid film landing point was kept at 100 mm, and the angle between the landing point on the web and the horizontal was set at 60 degrees. Table 1 shows the change in the limit coating speed when the web surface temperature (the web surface temperature is a value on the backup roller) was changed. In addition, when the flow rate of the coating is 4 cc / cm / sec, as shown in FIG. 1, when the web surface temperature is adjusted to 22 ° C. or more, the coating limit speed is greatly improved, and the coating is performed stably without any unevenness. It is particularly desirable that the temperature be 30 ° C. or higher,
The results are shown in Table 1 (Examples 1 to 8).

[0028]

[Table 1]

Next, the same coating liquid was used to adjust the viscosity of the lowermost layer to 90 cp.
(Shear rate 10 [1 / sec]), as a result of the same application, the same result can be obtained even if the viscosity of the lowermost layer is increased, as shown in Examples 9 to 11 in Table 2. Turned out as shown.

[0030]

[Table 2]

Further, when the static electricity is applied to the web and the web surface potential at the time of coating is set to 0.4 KV or 0.7 KV, and the coating is performed, as shown in Examples 12 to 17 in Table 3, the limit coating speed is further increased. You can see that it is higher.

[0032]

[Table 3]

Another embodiment will be described. On the undercoated cellulose triacetate film web, each layer having the composition shown below was coated simultaneously in multiple layers or divided twice to prepare a sample as a multilayer color photosensitive material. The composition of each layer is shown below.

(Composition of photosensitive layer) The coating amount is expressed in g / m ² of silver for silver halide and colloidal silver, and g for couplers, additives and gelatin.
/ M ² , and the sensitizing dye was represented by the number of moles per mole of silver halide in the same layer.

First Layer (Antihalation Layer) Black Colloidal Silver 0.2 Gelatin 1.3 Colored Coupler C-1 0.06 UV Absorber UV-1 0.1 UV Absorber UV-2 0.2 Dispersed Oil Oil -1 0.01 Dispersed oil Oil-2 0.01

Second Layer (Intermediate Layer) Fine Particle Silver Bromide (Average Particle Size 0.07 μ) 0.15 Gelatin 1.0 Colored Coupler C-2 0.02 Dispersed Oil Oil-1 0.1

Third layer (first red-sensitive emulsion layer) Silver iodobromide emulsion (2 mol% of silver iodide, average particle size 0.3 μ) 0.4 gelatin 0.6 sensitizing dye I 1.0 × 10 ^-4 sensitizing dye II 3.0 × 10 ^-4 sensitizing dye III 1.0 × 10 ^-5 Coupler C-3 0.06 Coupler C-4 0.06 Coupler C-8 0.04 Coupler C-20 .03 Dispersed Oil Oil-1 0.03 Dispersed Oil Oil-3 0.012

Fourth layer (second red-sensitive emulsion layer) Silver iodobromide emulsion (5 mol% of silver iodide, average particle size of 0.5 μm) 0.7 Sensitizing dye I 1.0 × 10 ^-4 Dye II 3.0 × 10 ^-4 Sensitizing dye III 1.0 × 10 ^-5 Coupler C-3 0.24 Coupler C-4 0.24 Coupler C-8 0.04 Coupler C-2 0.04 Dispersed oil Oil-1 0.15 Dispersed oil Oil-3 0.02

Fifth layer (third red-sensitive emulsion layer) Silver iodobromide emulsion (10 mol% of silver iodide, average particle size 0.7 μ) 1.0 Gelatin 1.0 Sensitizing dye I 1.0 × 10 ^-4 Sensitizing dye II 3.0 × 10 ^-4 Sensitizing dye III 1.0 × 10 ^-5 Coupler C-6 0.05 Gapler C-7 0.10 Dispersed oil Oii-1 0.01 Dispersed oil Oil- 2 0.05

Sixth layer (intermediate layer) Gelatin 1.0 Compound Cpd-A 0.03 Dispersed oil Oil-1 0.05

Seventh Layer (First Green Sensitive Emulsion Layer) Silver iodobromide emulsion (4 mol% of silver iodide, average particle size 0.3 μ) 0.30 Sensitizing dye IV 5.0 × 10 ^-4 Dye VI 0.3 × 10 ^-4 Sensitizing dye V 2.0 × 10 ^-4 Gelatin 1.0 Coupler C-9 0.2 Coupler C-5 0.03 Gambler C-1 0.03 Dispersed oil Oil-1 0.5

Eighth layer (second green-sensitive emulsion layer) Silver iodobromide emulsion (5 mol% of silver iodide, average particle size 0.5 μ) 0.4 Sensitizing dye IV 5.0 × 10 ^-4 Dye V 2.0 × 10 ^-4 Sensitizing dye VI 0.3 × 10 ^-4 Coupler C-9 0.25 Coupler C-1 0.03 Coupler C-10 0.015 Coupler C-5 0.01 Dispersed oil Oil-1 0.2

Ninth layer (third green-sensitive emulsion layer) Silver iodobromide emulsion (silver iodide 6 mol%, average particle size 07 μ) 0.85 gelatin 1.0 sensitizing dye VII 3.5 × 10 ^-4 Sensitizing dye VIII 1.4 × 10 ^-4 Coupler C-11 0.01 Coupler C-12 0.03 Coupler C-13 0.20 Coupler C-1 0.02 Coupler C-15 0.02 Dispersed oil Oil- 1 0.20 Dispersed oil Oil-2 0.05

Tenth layer (yellow filter layer) Gelatin 1.2 Yellow colloidal silver 0.08 Compound Cpd-B 0.1 Dispersed oil Oil-1 0.3

Eleventh layer (first blue-sensitive emulsion layer) Monodisperse silver bromide sweat (4 mol% silver iodide, average particle size 0.3 μm) 0.4 Gelatin 1.0 Sensitizing dye IX 2.0 × 10 ^-4 Coupler C-14 0.9 Coupler C-5 0.07 Dispersed oil Oil-1 0.2

12th layer (second blue-sensitive emulsion layer) Silver iodobromide emulsion (silver iodide 10 mol%, average particle size 1.5 μ) 0.5 gelatin 0.6 sensitizing dye IX 1.0 × 10 ^-4 Coupler C-14 0.25 Dispersed oil Oil-1 0.07

13th layer (first protective layer) Gelatin 0.8 UV absorber UV-1 0.1 UV absorber UV-2 0.2 Dispersed oil Oil-1 0.01 Dispersed oil Oil-2 0.01

Fourteenth Layer (Second Protective Layer) Fine Particle Silver Bromide (Average Particle Size 0.07 μ) 0.5 Gelatin 0.45 Polymethyl Methacrylate Particles (1.5 μm Diameter) 0.2 Hardener H- 1 0.4 Formaldehyde Scavenger S-1 0.5 Formaldehyde Scavenger S-2 0.5 In addition to the above components, a gelatin hardener, a gelatin preservative / antifungal agent, and a surfactant were added to each layer. The chemical formulas of the ultraviolet absorbent, dispersing oil, coupler, sensitizing dye and the like of each layer composition are shown in the attached table.

[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0054]

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[0055]

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[0056]

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[0057]

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[0058]

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In the case of simultaneous coating of all layers, the viscosity of the lowermost layer is 30 cp.
(Shear rate 10 [1 / sec]), the other layers have an average viscosity of 7
0 cp (shear rate 10 [1 / sec])
The flow rate per unit width of the free-fall coating liquid film was q = 7,10 in the case of multiple layers at the same time without changing the coating amount of the composition of each layer.
Water was prepared so as to be equivalent to [cc / m / s]. Table 4 shows the results.

In the case of the two-split coating, the viscosity of the lowermost layer, that is, the first layer and the seventh layer, is set to 30 cp (shear speed 10 [1/1).
sec]), and the other layers were adjusted to have an average viscosity of 70 cp (shear rate 10 [1 / sec]). Table 5 shows the results.

The distance between the lip portion of the slide hopper and the liquid film landing point for curtain coating was maintained at 200 mm, and the angle between the horizontal position of the landing point on the web and the horizontal was set at 60 degrees. When the web surface temperature (the web surface temperature is a value on the backup roller) was changed, the change in the limit coating speed was improved as shown in Tables 4 and 5 in Examples 18 to 23.

[0062]

[Table 4]

[0063]

[Table 5]

[0064]

As described above, according to the coating method of the present invention, the dripping phenomenon occurs in a high flow rate range of 2.5 to 10 cc / cm / sec of the coating liquid flowing down per unit length of the coating width of the curtain. Thus, it was possible to provide a curtain coating method in which the behavior of the curtain could be stabilized without causing the generation of a coating, a uniform coating film having no coating unevenness was formed, and the coating limit speed was improved.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a web surface temperature and a limit coating speed under a constant coating flow rate in a curtain coating method.

FIG. 2 is a perspective view showing a main part in one embodiment of the curtain coating method of the present invention.

[Explanation of symbols]

 Reference Signs List 1 coating head 2 backup roll 3 web 4 slit 5 curtain 6 curtain landing point 7 slide hopper 8 coating film

Claims (2)

[Claims] 1. A curtain coating method for a photographic light-sensitive material, wherein a coating liquid collides with a surface of a continuously running web as a free-falling liquid film and is applied to the coating liquid. A curtain for a photographic light-sensitive material, wherein a coating solution flow rate per contact is in a range of 2.5 to 10 cc / cm / sec, and a temperature of a surface of the web is adjusted from 22 ° C. to 55 ° C. for coating. Coating method. 2. The method according to claim 1, wherein static electricity is applied to the surface of the web before or during application, and the surface potential of the web during application is set to 0.1 to 0.8 KV. Curtain coating method for photographic photosensitive materials.