JPS623412B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for producing a photographic light-sensitive material, and more particularly to a method and apparatus for producing a silver halide photographic light-sensitive material having a paper support with improved curling properties. Generally, silver halide photographic materials have layers such as a silver halide emulsion layer containing gelatin as a binder or a protective colloid, a protective layer, etc., and these layers are coated on a photographic support by an air knife coating method, The coating is applied by a slide-botsper type extrusion coating method, etc., and then cooled and solidified with low-temperature air, and then supported and conveyed by a method such as hanging conveyance, horizontal conveyance, meandering conveyance, or air support conveyance, while drying air is applied. It is passed through and dried, and finally the moisture content is adjusted to a level suitable for storing silver halide photographic materials. In recent years, in order to improve productivity, there has been a demand for increased coating speeds, and along with this, there has been a demand for higher efficiency in the drying process, and rapid drying using high-temperature, low-humidity air has become necessary. However, it is known that when rapid drying is applied to a silver halide photographic light-sensitive material having a paper support, a serious quality defect occurs in that the curling properties of the light-sensitive material are significantly deteriorated. In order to improve the curling properties of silver halide photographic materials having a paper support, after the drying process has been completed, water vapor is directly sprayed onto the surface of the support opposite to the silver halide emulsion layer, and water is atomized. Conventionally, methods such as spraying, coating with an aqueous solution containing surfactant, etc. and drying have been used. It is either impossible to improve the curling properties of paper to a sufficient degree in terms of quality, or when it is possible to improve the curling properties of paper, these methods may cause problems such as paper wrinkles and blocking due to uneven moisture distribution caused by water droplets. It had drawbacks such as generating An object of the present invention is to provide a manufacturing method and apparatus capable of improving the curling properties of a silver halide photographic material having a paper support without causing defects such as paper wrinkles and blocking. Such an object of the present invention is to reduce the moisture content of the photosensitive material consisting of the coating composition and the paper support to 45% relative humidity after drying, when the liquid coating composition is coated on a paper support, cooled and solidified, and dried. This is achieved by bringing the moisture content below equilibrium and then contacting the side of the paper support opposite the coated layer with water vapor that has passed through the water vapor transmission control material. Water vapor permeation control materials used in the present invention are typically water-absorbent or hygroscopic fibers, and various cloths, papers, etc. are used. Cotton cloth is particularly preferred as these materials, but the thickness of the cotton cloth may be about 1 mm or less. The paper support according to the present invention includes baryta paper, document paper, etc. which are commonly used as photographic supports, and also includes general paper made from pulp. Various liquid coating compositions can be used for coating in the present invention. For example, silver halide emulsions containing silver halide and various photographic additives such as sensitizers, inhibitors, stabilizers, thickeners, etc., as necessary, as well as protective layers, filter layers, antihalation layers, etc. are formed. A coating composition containing physical development nuclei, and a coating liquid forming a diffusion transfer image-receiving layer containing physical development nuclei are applied. These liquid coating compositions mainly use gelatin as a protective colloid, but additives such as coating aids to facilitate coating and hardening agents to increase the physical strength of the gelatin coating are added. In the present invention, the method for drying the liquid coating composition applied onto a paper support is to blow high temperature and low humidity air onto the gelatin composition layer according to the process of a constant rate drying zone and a subsequent decreasing rate drying zone. . Above all, the dry bulb temperature is below 60℃ and the relative humidity is 20℃ throughout the drying process.
The effects of the present invention can be maximized in so-called rapid drying, in which air is blown at a concentration of 10% or less. Normally, the moisture content of the web at the end of drying is 45% to 65% relative humidity, taking into account the ability of the subsequent humidity control process.
The moisture content is adjusted to an equilibrium moisture content, and then a humidity conditioning process is performed to maintain a uniform and accurate moisture content that is optimal for preserving photographic materials within a relative humidity of 45% to 65% depending on the type of silver halide photographic material. However, in order to obtain the curl straightening effect by steam application in the present invention, the moisture content of the web at the end of drying is insufficient at the relative humidity of 45% to 65%, and the relative humidity is insufficient. Humidity 45% or less, preferably relative humidity 40%
It is essential to maintain the following so-called over-dry conditions. The steam applying step in the present invention will be explained based on the drawings. The dried web 1 passes over a steam application box 5 with the side of the paper support opposite to the coated layer facing down. Steam is continuously filled into the steam application box from a steam supply pipe 2 having a steam outlet 2'. The filled steam is led out from the exhaust port 3 by an exhaust fan (not shown) to the extent that it does not leak through the gap a between the web and the steam application box. The filled steam passes through the water vapor permeation control material 4 held by the holder and comes into contact with the web. The water vapor that comes into contact with the web is absorbed into the paper support as moisture due to the hygroscopicity of the paper support itself. The amount of moisture absorbed can be adjusted by changing the steam supply pressure and contact time depending on the type of web.
It is preferable to control the water vapor supply pressure within the range of 0.1 to 2.0 Kg/cm ² and the contact time within the range of 1 to 10 seconds. Partial excess moisture absorption and water droplet formation that occur with the normal method of directly spraying water vapor can be avoided by providing an exhaust port.
This can be effectively prevented by providing a water vapor permeation control material above the steam supply hole and exhaust port. According to the present invention, a silver halide photographic material having good curling properties can be obtained without providing a backing layer for improving curling properties, but it is optional to provide a backing layer if necessary. It is. Further, although the moisture content of the silver halide photographic light-sensitive material can be raised to a predetermined level by the steam application process itself, it is also possible to perform a humidity conditioning process in the next process. The liquid coating composition may also contain protective colloids other than gelatin, such as polyvinyl alcohol, gum arabic, cellulose derivatives, acrylamide, polyvinyl pyronon, etc., in combination with gelatin as a binder, if necessary. EXAMPLES Next, the present invention will be illustrated by examples, but the present invention is not limited thereto. Example An example using a steam applying device using cotton cloth with a thickness of about 0.5 mm as the water vapor permeation control material is shown below. Silver chlorobromide 2.7g/m ² and gelatin 8g/m ²
A silver chlorobromide emulsion layer and a protective layer containing 1.7 g/m ² of gelatin on the emulsion layer were coated in layers on 150 g/m ² baryta paper, and after cooling and solidifying, the following 4 steps were carried out.
Dry in different ways. Method A: Drying was carried out in air at a dry bulb temperature of 40° C. and a relative humidity of 20% until the moisture content was 7.7%. (Sample A). A moisture content of 7.7% corresponds to an equilibrium moisture content of 60% relative humidity. Method B: Drying was carried out in the same manner as in Method A, and then steam was applied to the anti-emulsion side of the baryta paper support for 5 seconds at a steam pressure of 0.3 kg/m ² using the steam applying apparatus shown in the figure. Method C: Dry with air at a dry bulb temperature of 40°C and a relative humidity of 20% until the moisture content is 6.6%, and then apply steam at 0.3 kg/cm ² using the steam applying device shown in the side view of the baryta paper support on the anti-emulsion side. Steam application was carried out at pressure for 5 seconds. A moisture content of 6.6% is relative to an equilibrium moisture content of 35% relative humidity. Method D: Drying was carried out in the same manner as in Method C, and then steam application was applied using the steam application device shown in the figure.
At that time, the exhaust of the steam application device was not activated and the cotton cloth was removed. Next, sample A obtained by the above methods A to D,
After keeping B, C, and D in an atmosphere with a dry bulb temperature of 20°C and a relative humidity of 60% for 24 hours, each sample was
Cut into 10 inch pieces, dry bulb temperature 20℃, relative humidity 20%,
The degree of curl (the degree of curl is expressed as the reciprocal of the radius of curvature when the unit of radius is m) was measured under conditions of 60% and 80%, and the results are shown in Table 1. .

[Table] Compared to comparative samples A and B, the curl degree of sample C according to the present invention is clearly lower under each relative humidity condition, demonstrating the effect. Comparative sample D showed the same degree of curl as sample C, but deteriorated physical quality due to water droplet adhesion and partial waving phenomenon.

[Brief explanation of the drawing]

1 and 2 show an example of the steam application device of the present invention. FIG. 1 is a cross-sectional view of the one-point intersection connecting B and B' in FIG. 2, viewed from the left, and FIG. A,
It is a cross-sectional view of the one-point intersection connecting A' when viewed from the right. FIG. 3 shows an example of a steam supply pipe having a steam blowing nozzle used in the steam applying device of the present invention. 1... Continuously running web, 2... Steam supply pipe, 2'... Steam outlet, 3... Steam exhaust port, 4... Water vapor permeation control material, 5... Steam application box.

Claims (1)

[Scope of Claims] 1. A method for producing a photographic material by coating at least one liquid coating composition on a paper support and drying the coating composition, after coating the liquid coating composition on the paper support. , the photosensitive material is dried, and the moisture content of the photosensitive material at the end of drying is reduced to 45% relative humidity equilibrium moisture content or less, and then the side of the paper support opposite to the coating layer is brought into contact with the water vapor that has passed through the water vapor permeation control material. Characteristic method for producing photographic materials. 2. In a photosensitive material manufacturing apparatus equipped with a device for coating at least one liquid coating composition on a paper support, a drying device, and a steam application device, a steam supply pipe having a steam blowing hole in the post-drying process. and a box section provided with a steam exhaust port is arranged on the opposite side of the steam permeation control material through which the web to be steamed passes.