JPH0222367B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photographic product in which a silver halide photographic light-sensitive material is sealed in a package. More specifically, the present invention relates to a method of significantly extending the life of a silver halide photographic material by setting a package for sealing the silver halide photographic material and conditions for sealing the material. Semi-permanently maintaining the photographic performance of a silver halide photographic material at the time of manufacture is a dream of those skilled in the art, and a fundamental challenge of the industry. Traditionally, deterioration of photographic performance due to long-term storage of silver halide photographic materials has been a problem.
In particular, the occurrence of fog due to an increase in the photosensitivity of a light-sensitive material shortens the life of the silver halide photographic light-sensitive material, and various proposals have been made for its improvement. For example, as a means of improvement under the condition of a relatively short storage period, it is widely known that various stabilizers are included in the photographic light-sensitive materials to suppress the occurrence of blurring, and in fact, they are effective to some extent. It was getting worse. However, adding a stabilizer to a photosensitive material is often accompanied by a decrease in other photographic properties of the photosensitive material, such as sensitivity or image density, and the effect over a long storage period is not as desired. Since it is extremely difficult to improve the photosensitive material itself, the method of improving the photosensitive material itself has not been satisfactory. At the same time, the molecular and electronic mechanisms involved in image formation in silver halide photographic materials are complex, and the causes of deterioration in photographic performance due to long-term storage are unclear. Even when it comes to measurements, the current situation is that it is not possible to solve problems using a theoretical approach. Therefore, an object of the present invention is to make it possible to maintain the photographic performance of a silver halide photographic light-sensitive material at the time of manufacture for a long period of time, and more specifically to prevent the occurrence of fog during long-term storage of the light-sensitive material. The object of the present invention is to provide a method for significantly extending the shelf life. According to the present invention, a package for a photographic light-sensitive material having a silver halide emulsion layer on a support is used, in which the oxygen partial pressure in the package is higher than the oxygen partial pressure at atmospheric pressure and 1 atm or less. It has been found that the above objects of the present invention can be achieved by the following methods. In general, in the food industry, etc., there is a technology that attempts to improve the shelf life of the food contents by sealing the contents in a package and reducing the pressure or replacing gas inside the package. It is a well-known place. However, this technique does not always give favorable results when applied to packaging of all types of contents. According to the knowledge obtained in the course of research by the present inventors, it was not possible to obtain satisfactory results even if such known techniques were applied as they were to the packaging of silver halide photographic materials. That is, when the present inventors tested the increase in fog due to long-term storage in the above-mentioned packaging form using a very basic and simplified system of silver halide photographic light-sensitive materials, most of the results showed that the packaging did not improve storage stability. I couldn't see any improvement. A method of sealing a silver halide photographic light-sensitive material in a specific package by reducing the oxygen partial pressure has already been described in JP-A-53-144727. The materials are limited to those containing photosensitive dyes, and even the method described in the above publication may not be effective when the type of photosensitive material is different, and in particular, the high-sensitivity photosensitive material targeted by the present invention may not be obtained. No effect could be expected on fogging that occurs during long-term storage of materials. However, a completely different phenomenon was observed in a package of silver halide photographic material in which the oxygen partial pressure in the package was higher than the oxygen partial pressure at atmospheric pressure and less than 1 atm. It has been clearly shown that, according to the method of the present invention, the increase in fog due to long-term storage of light-sensitive materials can be significantly suppressed, regardless of the presence or absence of light-sensitive dyes. In addition to the above methods, freezing preservation techniques can also be considered as a method for extending the storage period of silver halide photographic materials, but it is clear that the method according to the present invention is superior in terms of cost. The silver halide light-sensitive materials that can be applied to the present invention include black and white light-sensitive materials for general photography, as well as light-sensitive materials for various uses such as printing, X-rays, and radiation. Although any type of transfer-type photosensitive material may be used, an X-ray photosensitive material is most preferred. The silver halide photographic material according to the present invention will be explained below. The silver halide used in the silver halide emulsion layer of the above photographic light-sensitive material includes silver chloride, silver bromide,
These include silver chlorobromide, silver iodobromide, silver chloroiodobromide, and other well-known substances. These silver halide grains may be large or small, and their crystals may be normal or twin crystals, and any ratio of [100] planes to [111] planes can be used. Further, the crystal structure of the silver halide grains may be any layered structure, and may be either an internal latent image type or a surface latent image type, and the method for producing the silver halide grains is a commonly used known method. You can use . Next, binders for the emulsion layer of the light-sensitive material include gelatin, colloidal albumin, agar, gum arabic, alginic acid, partially saponified cellulose acetate, carboxymethyl cellulose, and synthetic binders such as polyvinyl alcohol and polyvinyl alcohol. Acrylamide, poly N-vinylpyrrolidone, etc. are used, but gelatin derivatives, gelatin graft copolymers, etc. are also widely used. Two or more of these binders can also be used in combination, if necessary. On the other hand, as a support for the photosensitive material according to the present invention, films, laminated paper, baryta paper, other metals, glass plates, and various other materials can be used depending on the purpose. Further, the emulsion layer of the above-mentioned light-sensitive material may contain various sensitizing dyes or desensitizing dyes. The package used in the present invention may have any shape as long as it can seal the silver halide photographic light-sensitive material, and is generally a cylindrical or prismatic container or a heat-sealed package. A typical example is packaging bags made from plastic. In the present invention, the most important thing is that the oxygen partial pressure in the package is greater than the oxygen partial pressure at atmospheric pressure and 1
By sealing the photosensitive material in the package under conditions such that the temperature is below atmospheric pressure, the oxygen partial pressure during the sealing process is also important, but the oxygen partial pressure during storage of the photosensitive material is always kept under the above conditions. It is important that the In general, atmospheric pressure means 1 atm, and the partial pressure of oxygen in the atmosphere is usually 1/5.
It is known that atmospheric pressure. The oxygen partial pressure in the package can be adjusted to 1/5 to 1 atm by reducing the pressure inside the package and sealing in oxygen. Note that a method may also be used in which a predetermined amount of an oxygen generating agent is placed inside the package during sealing, and after the package is sealed, the oxygen partial pressure conditions within the package are adjusted. Normally, whether the oxygen partial pressure is within a specified range is verified by measuring the total pressure of the gas inside the package, removing the gas inside, and measuring the gas composition using a mass spectrometer, etc. Bye. As oxygen gas filling packaging methods, there are known vacuum type gas displacement packaging and gas flash type gas displacement packaging. In the present invention, any of the vacuum type, nozzle gas filling type, chamber gas filling type, and pillow type gas flush type can be effectively used. In the present invention, the oxygen partial pressure at which the effect can be obtained is preferably 1/4 atmosphere or more, but even more favorable effects can be expected when it is 9/10 atmosphere or more. Materials for the packaging body used in the present invention include metal foils and glass such as aluminum, tinplate, lead, and iron, which are commonly used as packaging containers, or polyethylene, polypropylene, polystyrene, polyester, polyvinyl chloride, and polyvinylidene chloride. Examples include synthetic resins such as nylon, Teflon, and polycarbonate, synthetic resin foils with aluminum vapor-deposited, and other composite materials such as metal foils of 7μ or more, synthetic resin foils, and paper. The important criteria for selecting materials for these packages is that the oxygen permeability of the package should be 1×10 ^-4 cc/cm ²・24hrs・atm or less at 20°C and 0% relative humidity. The material and combination of materials should be selected in such a manner that the material and the combination of materials should be selected in such a manner that the oxygen permeability of the package should be selected to be close to zero. The oxygen permeability of the package is almost 0 when the oxygen permeability is 1×10 ^-5 cc/cm ²・24hrs・atm or less, and the package containing the photosensitive material is not stored for a long period of time ( This means that the rate of decrease in oxygen partial pressure in the package after storage (1 year 6 months to 2 years) is within 5% of the oxygen partial pressure at the start of storage. Considering these selection criteria, it is most effective to use metal, glass, or a composite material using metal as the package. The amount of oxygen permeation Q is expressed by the following equation. That is, Q=〓(P ₁ − P ₂ )/・a・t Here, the thickness of the package, a is the surface area of the package, t is time, and P ₁ and P ₂ are the oxygen partial pressures outside and inside the package. and 〓 is the oxygen permeability coefficient. In the present invention, oxygen permeability refers to (〓/), and its unit is cc/cm ² ·24hrs ·atm. That is, it is expressed as the number of cc of oxygen that passes through a material with a pressure difference of 1 atm and a surface area of 1 cm ² in one day. From Fitzke's equation, the gas volume inside the package (V _c )
and pressure (P _c ) do not change during long-term storage,
The relationship between the change in oxygen partial pressure inside the package (dP ₂ ) with respect to the change in time (dt) is derived from the following equation.
That is, _dP2 /dt= _〓Pca / _Vc ( _p1 - _p2 ) When this is solved, the oxygen partial pressure inside the package after storage for t days is expressed by the following equation. That is, Here, P ₀ is the oxygen partial pressure inside the package at the start of long-term storage. Also, since P ₁ is the oxygen partial pressure in atmospheric pressure, it is 0.2, and P _c is 1, so the following equation is obtained.
That is, Using this formula, it is possible to store at any oxygen partial pressure for any period of time. For example, plastic film (processing and application)
Edited by Plastic Film Research Group (Gihodo) P173
From Table 4.14, find 〓(cccm/ ^cm2・24hrs・atm), and calculate the thickness of the package (), internal gas volume (V _c ),
The surface area (a) is determined as shown in the following figure.

[Packaging conditions 2]

Another one of the above samples was placed in the same packaging material as in Packaging Condition-1 and sealed under the same conditions as Packaging Material 1, including an oxygen partial pressure of 1/4 atm and a nitrogen partial pressure of 3/4 atm. [Packaging Condition 3] Another one of the above samples was placed in the same packaging material as Packaging Condition-1, and the oxygen partial pressure was 49/50 atm, and the nitrogen partial pressure was 1/50.
The air pressure and other conditions were the same as in packaging condition 1 and sealed. [Packaging condition 4] The other packaging material is a low-density polyethylene can with a thickness of 0.5 mm and the same surface area and internal volume as packaging condition 1 (relative humidity 0%, oxygen permeability at 20°C: 2.4 × 10 ^-2
cc/cm ² .24 hrs.atm), and after putting another one of the above samples into this polyethylene can, it was sealed and packaged under the same air conditions as packaging condition-1. In addition, the polyethylene can has a cap part and a cylindrical body part that are fitted together with screws,
The mating threads and valleys are filled with silicone compound. [Packaging Condition 5] Another one of the above materials was placed in the same packaging material as in Packaging Condition-4 and sealed under the same conditions as Packaging Condition-2. [Packaging Condition 6] Another one of the above samples was placed in the same packaging material as in Packaging Condition-4 and sealed under the same conditions as Packaging Condition-3. The sample obtained in the above manner was brought to atmospheric pressure (1 atm).
The film was left in an air-conditioned room at 30° C. and 55% relative humidity for 1 hour and 2 years, and then exposed and developed using the method described below. In other words, the maximum wavelength of generation is 530 to 550 nm.
In an X-ray imaging device with a fluorescent intensifying plate of
After irradiating X-rays at 100KVP, 100mA, for 0.10 seconds through an aluminum wedge, a general automatic developing machine for 90 seconds of X-ray processing (QX- manufactured by Konishiroku Photo Industry Co., Ltd.) was used.
1200). The obtained silver image was checked for fog using a transmission densitometer (manufactured by Konishiroku Photo Industry Co., Ltd.).
Sensitivity was determined. The results obtained are shown in Table 1 below. Note that the sensitivity is expressed as a relative value with the sensitivity immediately after preparation of each sample as 100.

【table】

[Packaging conditions 1]

A composite film consisting of kraft paper (60μ thick), aluminum (9μ thick), and low-density polyethylene (50μ thick) blackened with carbon black (relative humidity 0%, oxygen permeability 0 c.c. at 20°C) from the outside. / ^cm2・
24hrs・ATM) 3-side seal packaging bag (surface area: 1920
One of the above samples was placed in air at 23° C. and 55% relative humidity in a chamber (cm ² , internal volume 900 cm ³ ), and then sealed with a heat seal. [Packaging Condition 2] In the same packaging bag as Packaging Condition-1, oxygen partial pressure is 9/10 atm, nitrogen partial pressure is 1/10 atm, other conditions are the same as Packaging Condition-1, and another one of the above samples is placed. and sealed it. [Packaging conditions 3] Composite film made of vinylidene chloride (2 mm thick) and low density polyethylene (40 μ thick) (relative humidity 0)
%, oxygen permeability at 30℃ is 1×10 ^-5 cc/cm ²・
Another one of the above samples was placed in a 3-side sealed packaging bag (surface area and internal volume are the same as packaging condition 1) of a 24hrs ATM) under the same conditions as packaging condition 1, and the bag was sealed with a heat seal. [Packaging Condition 4] The remaining sample was placed in the same package as Packaging Condition-3 under the same conditions as Packaging Condition-2, and the package was sealed with a heat seal. After storing the sample obtained as above at atmospheric pressure (1 atm) and room temperature for 1 hour and 1 year and 6 months, the sample was opened and the maximum wavelength of generation was 300~
The sample was sandwiched from both sides with a 400 nm fluorescent intensifying screen and exposed to X-rays at 80 KVP and 200 mA for 0.05 seconds through an aluminum wedge using an X-ray imaging device.
Development and density measurements were performed in the same manner as above, and fog and sensitivity were determined. The results obtained are shown in Table 2 below. Note that the display of sensitivity is the same as in Example-1.

[Table] As is clear from Table 2 above, sample No. 2, which meets the conditions of the present invention and is sealed in a package made of a composite material with an oxygen permeability of 0, has a higher fog increase than other samples. I found that progress was very slow. Furthermore, even if the oxygen permeability is not 0, it is possible to delay the increase in fog as in sample No. 4 by selecting a resin composite material with low air permeability as shown in this example. I understood. Example 3 A silver chloroiodobromide emulsion containing 0.4 mol % of silver iodide and 25 mol % of silver bromide was prepared by a double jet method to prepare an emulsion for ultra-high contrast printing photosensitive material. The resulting emulsion had silver halide grains with an average grain size of 0.3μ, and a grain size of 80%.
The above silver halide grains had a cubic system with [100] faces. After gold sensitization and sulfur sensitization to this emulsion, the following sensitizing dyes (A) and (B) were added together in mg per mol of silver halide, and then 4-
Stabilization was achieved by adding 0.5 g of hydroxy-6-methyl-1,3,3a,7-tetrazaindene, followed by 1.5 g of saponin, 50 mg of polyethylene oxide (molecular weight 2000), and 400 mg of mucochloric acid per mole of silver halide. Sample emulsions were prepared by sequential addition. (Sensitizing dye A) (Sensitizing dye B) Next, this sample emulsion was applied to a subbed polyethylene terephthalate film base and dried. This sample was divided and packaged under the following conditions. The surface area and internal volume of the packaging bag are the same as in Example 2.
That is, a three-sided sealed packaging bag made of a composite film made of nylon (40μ thick), aluminum (7μ thick), and polyethylene blackened with carbon black (40μ thick) (at 20°C and relative humidity 0%, the oxygen permeability is
After putting one of the above samples into a container (cc/cm ² .24 hrs.atm), it was sealed by heat sealing at a temperature of 23° C. and a relative humidity of 51% and oxygen partial pressure being the same as that of the atmosphere. In addition, as another packaging condition, after putting another one of the above samples into the same packaging bag, the temperature and relative humidity are the same, the oxygen partial pressure is 9/10 atm, the nitrogen partial pressure is 1/10.
It was sealed by heat sealing under atmospheric pressure conditions. The packaged sample obtained in this way was left at room temperature under atmospheric pressure (1 atm) for 2 years, then opened and exposed to a light source with a color temperature of 5400K, illumination intensity of 64 lux for 0.02 seconds, KS
Wedge exposure was performed using a Type-1 sensitometer (manufactured by Konishiroku Photo Industry Co., Ltd.). Next, it was developed for 1.5 minutes at 20°C with a developer containing metol and hydroquinone as main ingredients.
After fixing, washing with water, and drying, characteristic curves of each sample were determined using a Sakura PDA-60 densitometer, and fog and sensitivity were measured. The results are shown in Table 3 below. Note that the sensitivity display was the same as in Example-1.

[Table] As is clear from Table 3 above, packaging samples with increased oxygen partial pressure have less increase in fog due to storage.
It was found that there was only a slight decrease in sensitivity and that it exhibited excellent stability. Separately from the above development, the wedge-exposed, unsealed sample was processed using a roller conveyance type automatic developer (Sakura G-17 automatic developer) at a developer temperature of 27°C using an infectious developer containing hydroquinone as the main ingredient.
Development was performed for 2 minutes. Measure the density of each sample, and calculate the fog, sensitivity, and density at the foot of the characteristic curve (base density + fog density +
The slope of the straight line connecting density 0.05) and density 0.5, that is, the contrast of the low density part of the characteristic curve was measured. The results are shown in Table 4 below. Note that the sensitivity was displayed in the same manner as in Example-1.

[Table] As is clear from Table 4 above, even when processed with an infectious developer, the fog, sensitivity, and contrast deterioration in low-density areas of the samples stored under the packaging conditions of the present invention are the same as those in normal packaging. It was found that there were very few compared to

Claims (1)

[Claims] 1 A photographic product obtained by sealing a silver halide black-and-white photographic material having a silver halide emulsion layer on a support in a package, in which the oxygen partial pressure in the package is equal to or less than the oxygen partial pressure at atmospheric pressure. A photographic product characterized by being larger and having a pressure of 1 atm or less.