US3857710A - High contrast, high capacity monobath processing method and composition for monochrome film - Google Patents

Abstract

Improved monobath processing methods and compositions yielding high contrast and low fog in monochrome silver halide emulsion films while possessing high processing capacity. The monobath compositions contain two alkali agents and have a maximum of 40 grams of anhydrous sodium sulphite preservative per 1,000 milliliters of solvent. The invention is particularly advantageous for applications wherein film is used to record instrument data-readouts.

Description

United States Patent [191 Speers Dec. 31, 1974 HIGH CONTRAST, HIGH CAPACITY MONOBATH PROCESSING METHOD AND [73] Assignee: General Film Development Corporation, Southport, Conn.

[22] Filed: Dec. 22, 1972 [21] Appl. No.: 317,763

[52] US. Cl. 96/61 M, 96/66 R, 96/66 HD, 96/66.3

[51] Int. Cl G036 5/38, G03c 5/30 [58] Field of Search.... 96/61 M, 66 R, 66.3, 66 HD [56] References Cited UNITED STATES PATENTS 3,017,270 1/1962 Tregillus et a1. 96/61 M 3,220,838 11/1965 Humphlett et a1. 96/61 M 3,240,603 3/ 1966 Schuler et a]. 96/61 M 3,615,513 10/1971 Haist et a1. 3,705,806 12/1972 Sykes et a1. 96/61 M Primary ExaminerMary F. Kelley Attorney, Agent, or Firm-Bryan, Parmelee, Johnson 8L Bollinger 5 7 ABSTRACT Improved monobath processing methods and compositions yielding-high contrast and low fog in monochrome silver halide emulsion films while possessing high processing capacity. The monobath compositions contain two alkali agents and have a maximum of 40 grams of anhydrous sodium sulphite preservative per 1,000 milliliters of solvent. The invention is particularly advantageous for applications wherein film is used to record instrument data-readouts.

2 Claims, No Drawings HIGH CONTRAST, HIGH CAPACITY MONOBATH PROCESSING METHOD AND COMPOSITION FOR MONOCIIROME FILM BACKGROUND OF THE INVENTION This invention relates to combined developer-fixer photographic processing compositions, commonly known as monobaths, for monochrome silver halide emulsion films and, more particularly, to monobath compositions producing high contrast images while exhibiting a high processing capacity.

An increasingly commercially important use of monochrome film of the silver halide type is for recording and preserving data information. Thus, these films are often used to record the readings of instrument dials, number registers, cathode ray tube displays, medical instrumentation displays and the like. In these and other applications it is often desirable for inspecting personnel to be able to examine the film as soon as possible after exposure for recording purposes. Therefore, in these instances, it is preferable that the film be processed in as short a time as possible. Additionally, since the instruments photographed and inspecting personnel are often situated in commercial installations such as factories, plants, hospitals, and the like, it is frequently necessary that the film be processed on site, under ordinary conditions, in as convenient and trouble free manner as possible. Moreover, the exposed film should produce an image of high quality with good grain structure and contrast and little or no fog so that an accurate and readily comprehensible reproduction of the instrument readout is provided and preserved.

Conventional processing of such instrument recording film would require a three or four-step photographic processing cycle that involves a developing solution, a stop bath, at fixing solution and a final wash. With conventional chemistry, the total processing time easily consumes 10 to 30 minutes not including an additionaltime for washing. Although conventional time can be shortened by heating the solutions to accelerate developing and fixing, such heating necessarily requires close monitoring of time and temperature. In addition, high temperature processing reduces the active life of the developer and increases the danger of fog in the finished product. Additives such as anti-fogging compounds, hardeners and substances which reduce the swelling of the film gelatin arising from change of processing parameters to increase speed can be added to conventional formulas. However, these result in increased costs, complexity of the solution and nevertheless often fail to satisfactorily reduce chemical fog and frequently reduce developer life.

The present invention finds particular utilization in processing monochrome silver halide emulsion films normally used in instrumentation applications by providing monobath compositions which exhibit a high capacity for development and short processing time while producing high contrast with little or no fog. Monobaths have been commercially available from time to time, however, many are withdrawn because of various shortcomings of the processing solutions. A comprehensive discussion of monobaths, including representative formulations, is presented in Monobath Manual, Grant Haist, Morgan & Morgan, Inc., Hastings-on- Hudson, New York (1966). In my copending applications, Ser. No. 233,787, filed Mar. 10, 1972 now U.S. Pat. No. 3,819,378 for Fine Grain High Speed Photographic Processing Monobath Composition and Method, and Ser. No. 240,275, filed Mar. 31, 1972 now U.S. Pat. No. 3,806,344 for Three Component Developer Photographic Processing Monobath composition and Method, I described generally the photographic processing behaviour of monobath compositions and the dependence of improved characteristics I and behaviour of the monobath upon the total composition of solution rathen than upon the individual components. The reader is referred to those applications, and those general observations are incorporated herein for reference, for background information which will be of assistance in understanding the improved monobath composition and method of the present invention. The monobath composition and method of the present invention is yet a further improvement in monobaths and monobath processing and is characterized by faster processing time, higher contrast in the developed image and a reduced tendency to produce fog.

SUMMARY OF THE INVENTION The monobath processing method and compositions of this invention achieve high contrast images in monochrome silver halide emulsion films by providing a monobath containing both strong and weak alkali agents while limiting the amount of anhydrous sodium sulphite preservative to a maximum of 40 grams per 1,000 milliliters of solvent. By providing such a composition, an image of higher contrast and reduced fog is obtained while fast processing time is maintained. Sludge and sediment may be kept low through the presence of additives thus providing the solution with a long shelf and processing life.

Thus, it is an object of this invention to provide a high contrast, high capacity monobath for silver halide emulsion monochrome films. A further object of the invention is the provision of a monobath composition having improved resistance to oxidation and sediment formation, resulting in increased processing life and long shelf life.

High contrast is particularly advantageous in silver halide films used to record instrument data, especially so printed copies may then be readily made by conventional electrostatic methods. Further, in instrumentation applications, it is desirable to process the films rapidly for quick visual readout and as conveniently as possible so that they may be done on site either manually or in machines with a minimum number of steps and preferably under ambient room temperature conditions.

Thus, it is yet a further object to this invention to provide a monochrome silver halide film monobath processing method and composition which permits convenient and efficient high speed processing, either manually or by machine, of films used in instrument recording applications. Further objects and advantages of the invention will be apparent from the preferred embodiments thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The monobath processing method and compositions according to this invention depart from the suggested formulations of other experimenters. In the conventional approach to monobath formulations, the developer concentration is upwards of five times the amount required for a developer-only solution used in the conventional multi-step processing method. At the same time, the pH is raised with a strong alkali such as sodium or potassium hydroxide and the fixer, usually sodium thiosulphate, concentration is kept low in order to yield the desired contrast. However, this approach results in longer processing time since increasing the sodium thiosulphate fixer content to reduce the time required for full processing undesirably reduces the contrast of the film. Additionally, most formulators of monobath processing solutions teach the inclusion of the preservative sodium sulphite in an approximate amount of 50 grams anhydrous sodium sulphite per 1,000 mulliliters of solvent, such as water, in those monobaths where the developer, such as hydroquinone (1,4-dihydroxybenzene), content is in excess. of 25 grams per 1,000 milliliters.

In the monobath compositions of the present invention, 40 grams anhydrous sodium sulphite per 1,000 milliliters water is the maximum amount of preservative, while 25 grams per 1,000 milliliters is preferred. The amount of hydroquinone does not exceed 25 grams per 1,000 milliliters water, while the preferred amount is lower.

l have found that monobaths having the following compositions have excellent keeping and exhaustion properties, produce little or no fog and are resistant to the formation of sludge or sediment even after extensive use for processing. The monobath composition according to this invention is as follows:

The amount of anhydrous sodium sulphite used in the formula should be kept below 40 grams per 1,000 milliliters of solvent in order to preserve the high contrast and sharpness desired in the film image. The sodium sulphite not only inhibits the atmospheric oxidation of the developing agents but also plays an important part in the developing process by helping to remove products which would otherwise interfere with the controlled developing process. ln this instance, since the primary developer is hydroquinone, the sulphite combines with quinone which is the oxidation product of hydroquinone to form a sulphonate which is a colorless, water soluble by-product that has little or not effect upon the course of development. Bisulphites can be substituted for the sulphite, along with a corresponding increase in the amount of alkali, however, such is to be done only in cases where it is desirable to concentrate the solution or to prepare the composition in two separate solutions.

Hydroquinone is the preferred developer since it is clean working and non-staining and gives high contrast under rapid working conditions. l'lydroquinone maintains itself well in solution and has a slow exhaustion rate. When used in the amounts given above, it is not especially temperature sensitive thus permitting a wider latitude to the use of the monobath under ambient conditions such as room temperature. phenidone is included as a second developer in small amounts because it is superadditive with the hydroquinone, keeps well, has low toxicity and is fast working. Metol (lhydroxy-4-methylaminobenzene) may be substituted for phenidone if the latter is not available, however, this increases the oxidation susceptibility of the composition and there is a greater tendency to produce excessive fog.

The presence of two alkali constituents in the monobath compositions of this invention is an important feature. The strong or caustic alkali such as sodium or potassium hydroxide provides energetic action giving more rapid development and reduces the amount of alkali required. However, too much caustic alkali yields a solution of poor-keeping qualities. The use of a second alkali of the carbonate type, such as sodium or potassium carbonate, permits the use of less caustic alkali and at the same time preserves the useful life of the monobath composition over a greater length of time and reduces its exhaustion rate. The amount of alkali preferred is as given above, however increasing the amount will provide greater contrast while decreasing amount will decrease the contrast.

The amount of sodium thiosulphate included in the composition is dependent upon the speed of clearing desired and the gamma'range required. Increasing the amount of this fixing constituent speeds clearing but reduces the gamma range and the reverse holds. Since the gamma value of the film will be fixed by the composition in the monobath, best results are obtained using thepreferred amounts set forth above.

Benzotriazole'is included in the composition as an anti-fogging agent which does not affect other properties of the developer. This compound id particularly effective against fogging at elevated temperatures and with extended processing times. Nitrobenzimidazole can be substituted for the benzotriazole, if desired. These agents are preferred over other anti-foggants such as potassium bromide or potassium iodide since the latter exhibit a restraining action on the developers. Sludge and sediment in the solution can be restricted by adding to the composition EDTA Tetrasodium Salt, such as that available under the name Versene. While the former is preferred, also used may be sodium hexametaphosphate or ethylenediaminetetraacetic acid.

All constituents set forth herein are commercially available and the photographic grade should be used unless other grades meet the required degree of purity. The water should be distilled, and preferably deionized, water.

The following specific examples of monobath compositions of this invention will process monochrome silver halide film with a little of no fog and high contrast in the image being obtained. These monobath solutions are resistant to the formation of sludge and sediment even after processing up to 10 rolls of -136 film of Kodak PLUS-X type in twenty ounces of solution.

EXAMPLE LCominued films at normal room temperature to obtain a high contrast, low fog image, consisting essentially of the follow- Malerial Amount iriigleflonstltuents 1n the proportionate weight amounts Phenidone 0.5 g. g Benzotriazole 0.5 g. 5 EDTA Tetrasodium Salt 1.5 g. g Sodium Thiosulphate 110 g. Material Parts by Weight Water 1000-1005 Anhydrous Sodium Sulphite 15-40 Hydroquinone 9-25 EXAMPLE 2 10 Sodium or Potassium Hydroxide 3-8 Anhydrous Sodium or Potassium Carbonate 2-10 Material Amount Phenidone 0.1-0.8

Benzotriazole 0-2 EDTA Tetrasodium Salt 0.5-3 Water 1000 ml.* Anhydrous Sodium Sulphite 25 g. sodlum Thmsulphate 50425 Hydroquinone g. 15 Sodium Hydroxide 6.5 g Anhydrous Sodium Carbonate 7.5 g Phenidone 04 g 2. A method for efficiently and permanently record Benzotriazole 0.6 g mg an instrument reading occurring at a particular inggf g g zg g stant and making the reading nearly immediately availp g able in a form intelligently perceptible to the human Depending on the processing temperature, 1000 milliliters of water constitutes eye comprising, exposing a monochrome silver halide moomos grams emulsion film to the reading to obtain an image thereof,

immersing the film in a monobath photographic propependntig on the i the above cfomposltglons l cessing solution for approximately four to five minutes qulre pre erred delle Opment.nme of our We m at normal room temperature, the monobath composimes with fresh splutlon and hghtly longel wlth tion consisting essentially of the following constituents ously used solutions. These times may be increased or in the to Ortionate Wei ht amounts iverr decreased by varying the fixer content. Recommended p p g g developing temperature is between 25 to 40C. Lower temperatures increase, and higher temperatures de- Material P ns by Weight crease the processing time. The compositions will process films of Kodak PLUS-X and Kodak TRI-X types, mjg Sodium Sulphite {2925 as well as high contrast copy films X-ray film instru- Hydroquinone 9-25 mentation films. Because of their versatility these comiz g g i gggfi fxt mggg fs Carbonate 3:? positions can be used to process films on site immediphenidone 0 g ately after they have been used to photograph mstrugE g r San 8- B l' "lent fFadlngs' Sodium Thiosulphate 50-125 I claim: 1. A high capacity, high contrast monobath solution and obtaining a high contrast, low fog image thereon. for photographic processing of silver halide emulsion

Claims (2)

1. A HIGH CAPACITY, HIGH CONTRAST MONOBATH SOLUTION FOR PHOTOGRAPHIC PROCESSING OF SILVER HALIDE EMULSION FILMS AT NORMAL ROOM TEMPERATURE TO OBTAIN A HIGH CONTRAST, LOW FOG IMAGE, CONSISTING ESSENTIALLY OF THE FOLLOWING CONSISTUENTS IN THE PROPORTIONATE WEIGHT AMOUNT GIVEN: MATERIAL PARTS BY WEIGHT

2. A method for efficiently and permanently recording an instrument reading occurring at a particular instant and making the reading nearly immediately available in a form intelligently perceptible to the human eye comprising, exposing a monochrome silver halide emulsion film to the reading to obtain an image thereof, immersing the film in a monobath photographic processing solution for approximately four to five minutes at normal room temperature, the monobath composition consisting essentially of the following constituents in the proportionate weight amounts given: