US3060028A

US3060028A - Stabilized photographic silver halide emulsions containing iodine complexes of poly-n-vinyl-2-oxazolidinones

Info

Publication number: US3060028A
Application number: US83647A
Authority: US
Inventors: Dersch Fritz
Original assignee: General Aniline and Film Corp
Current assignee: GAF Chemicals Corp
Priority date: 1961-01-19
Filing date: 1961-01-19
Publication date: 1962-10-23
Anticipated expiration: 1979-10-23
Also published as: GB989891A

Description

3,060,028 STABHJZED PHOTOGRAPHIC SILVER HALIDE EMULSIONS CONTAINING IUDINE (30M- PLEXES F POLY-N-VINYL 2 OXAZOLIDI- NONES Fritz Dersch, Binghamton, N.Y., assignor to General Aniline & Film Corporation, New York, N.Y., a corporation of Delaware N0 Drawing. Filed Jan. 19, 1961, Ser. No. 83,647 6 Claims. (Cl. 96-66) This invention relates to light sensitive silver halide photographic emulsions stabilized with iodine complexes of poly-N-vinyl-Z-oxazolidinones and to methods of preparing such stabilized emulsions.

It is known that silver halide photographicemulsions, when stored for any length of time, becomes spontaneously developable without exposure to light. Consequently, when photographic elements containing excessively aged emulsion are exposed and developed, there is formed, even in the unexposed areas of the plate, a certain amount of developed silver. Optical opacity produced in the unexposed areas is commonly referred to as fog, and emulsions which give rise to this condition are designated as fogged emulsions.

The phenomenon of fog in photographic emulsions has engaged the attention of photographic chemists for many years. It has been studied in great detail and numerous reasons have been put forth to account for its occurrence. For instance, emulsions stored under conditions of high humidity tend to grow foggy. In fact, it is a common practice to test photographic emulsions by subjecting them to excessive humidity and/or temperature. Such information, of course, is very important, since many emulsions may encounter the aforedescribed conditions in tropical climates. Photographic fog also can be produced by exposure to chemicals, such as hydrogen, sulfide, or other reactive sulfur compounds, including strongly reducing materials, some of which may occur in the atmosphere.

A large number of substances known to the art an antifoggants and/or stabilizers have been described in the literature as being eifective in retarding fog when such entities are incorporated in light sensitive silver halide emulsions. In this connection, reference is made to the mercapto derivatives of benzothiazole, benzimidazole and other related azoles. Although these compounds have been found eifective for reducing or retarding fog buildup, there is produced a secondary efiect which manifests itself in a generally lowering of sensitivity and speed of the emulsion and in some instances may even reduce its optical or dye sensitization.

It has now been discovered that photographic light sensitive silver halide emulsions, which have been stabilized with certain poly-N-vinyl-Z-oxazolidinones in the form of their iodine complexes, remain remarkably free of any tendency toward fog build-up on storage, and yet emulsions stabilized in this manner maintain their overall photographic sensitivity. The provision of silver halide photographic emulsion stabilized or protected by the action of iodine complexes of poly-N-vinyl-Z-oxazolidinones constitute the purposes and objects of this invention.

The poly-N-vinyl-Z-oxazolidinone iodine complexes which I have discovered to be excellent antifoggant agents for silver halide emulsions are known entities and are de scribed in the chemical literature; Chem. and Engr. News, September 5, 1960 (pp. 56-57). Such compounds 3,h0,028 Patented Oct. 23, 1962 can be formulistically illustrated by the following type of general formula:

wherein n is a whole integer, the value of which is sufficient to produce a polymer having an average molecular weight of about 150,000, and R is selected from the class consisting of hydrogen and lower alkyl groups.

I have ascertained that the iodine complex of poly-N- vinyl-5-methyl-2-oxazolidinone having an average molecular weight of about 150,000 has excellent antifoggant properties for greatly retarding fog in silver halide emulsions. This particular poly-2-oxazolidinone was purchased on the open market under the trade name Devlex, and is sold under this name by the Dow Chemical Company. As the iodine complex, poly-N-vinyl-5-methyl- -oxazolidinone contains 5.1% free iodine, which is bound to the polymer molecule analogously to iodine in the familiar starch iodine complex.

The aforementioned compounds can be utilized in various ways in order to secure beneficial efiects and fog reduction. For instance, the components can be incorporated in the silver halide emulsions as ripening finals or as coating finals. Ripening finals are added during the ripening or the sensitivity increasing stage of the emulsion making process. These additions may be made before, during or after the double decomposition reaction between the soluble silver salt such as silver nitrate and the soluble halide, such as potassium bromide in the presence of a colloid carrier. By colloid carrier is intended the medium in which is contained the light sensitive silver halide salts. Typical examples of such carriers include gelatin, PVA, solubilized casein, carboxymethyl cellulose, albumin and the like.

Coating finals are customarily added to the emulsion just prior to coating on a suitable support such as glass, paper, or film, at a time when the emulsion is approaching its maximum sensitivity.

When used as a ripening final the poly-N-vinyl-Z- oxazolidinone-iodine complex is preferably used in a concentration ranging from 1 to milligrams per 0.4 mole of silver halide, and, when used as coating finals is employed in a ratio varying from 10 to 300 milligrams per 0.4 mole of silver halide. The concentration will vary with the various types of emulsion which is used and it is advisable to determine the optimum concentration from case to case. In some instances, it is desirable to apply this group of antifoggants and stabilizers in adjacent layers, e.g., in a separate undercoating layer or in the anti-abrasion gelation surface. In other cases, it may be desirable to utilize them in one or all of the processing baths or in preand postbaths.

The antifoggants as described herein can be advantageously employed in connection with any type of photographic emulsion, e.g., non-sensitized, orthochromatic, panchromatic, X-ray emulsions, paper emulsions, color emulsions or the like. It has also been ascertained that the compounds of the invention are capable of use in combination with other known antifoggants and stabilizers, as well as other photographic adjuncts such as reduction and metal and noble metal sensitizers and in combination with a hydroxy polyphenoxy derivative of the type obtained by reacting ethylene oxide with alcohol phenol amine or the like as described in U.S.P. 1,970,578.

The invention is illustrated by the following examples, but it is to be understood that the invention is not to be restricted thereto.

Example I A silver halide emulsion in gelatin containing 4% silver iodide and 96% silver bromide was prepared in a conventional manner and brought up to its maximum light sensitivity and then readied for coating. Finals were added such as sensitizing dyes, stabilizers and hardening agents. A 1.0% (by Weight) solution of the iodine complex (5.1% free iodine) of Devlex l30-previously described herein-in water was prepared and added to the emulsion as an antifoggant and stabilizer. The emulsion samples contained about 0.4 mole of silver halide. The so-prepared emulsion samples were coated on a suitable cellulose ester base and dried. Samples of these film coatings were exposed in a Type 113 sensitometer and developed in a developer of the following composition:

Grams Metol 1.5 Sodium sulfite, anhydrous 45.0 Sodium bisulfi 1.0 Hydroquinone 3.0 Sodium carbonate, monohydrated 6.0 Potassium bromide 0.80 Water to make 1.0 liter Quantity of Compound Relative Fog at Oven Oven Fog Added Speed 14 Dev. Speed at 7 Dev.

Beneficial effects in fog reduction may be obtained when solutions of polyvinyloxazolidinone iodine are incorporated in the silver halide emulsions as ripening finals or as coating finals. Ripening finals are added during the ripening or the sensitivity increasing stage of the emulsion making process. Such additions may be made before, during or after the addition of the soluble silver salt to the soluble halides in presence of a suitable colloid, such as gelatin, PVA, solubilized casein or albumin. Coating finals are added to the emulsion just prior to coating it on a suitable support (glass, paper, film) when the emulsion has nearly obtained its maximum sensitivity.

When used as ripening finals, polyvinyloxazolidinone iodine is best used in a concentration of l to 100 milligrams per 0.4 mole of silver halide and when used as coating final in a concentration of ten to 300 milligrams per 0.4 mole of silver halide. The concentration used depends very much on the type of emulsion which is used, and it is advisable to determine the optimum concentration from case to case. In some cases it is advantageous to apply PVC-iodine in adjacent layers, e.g., in a separate undercoating layer or in the antiabrasion gelatin surface. In other cases, it is desirable to apply them in one or all processing baths or in preand postbaths. PVC-iodine may be used in various kinds of photographic emulsions, e.g., non-sensitized, orthochromatic, panchromatic, X-ray emulsions, paper emulsions, color emulsions.

PVC-iodine may be used in combination with other known anti-foggants and stabilizers, also in combination with sulfur, reduction and metal, and noble metal sensitizers also in combination with polyoxyalkylenes, their derivatives and other accelerators such as polyvinylpyrrolidone (PVP) or poly-N-vinyl-2-oxazolidinone.

The iodine complex of a poly-N-vinyl-2-oxazolidinone is prepared by mixing a solution of the oxazolidinone polymer in a solvent therefor such as methanol, ethanol, or methylene chloride with a solution of iodine in a similar solvent. If desired, an aqueous solution of polyvinyl oxazolidinone may be combined with an aqueous solution of iodine such as Lugol solution followed by mixing. The resulting mixed solutions, which now contain the polyvinyloxazolidinone iodine complex, may be used directly if desired or the solutions may be reduced to a dry powder for subsequent redissolution in water. Lugol solution is known to the art and commonly comprises a solution containing 5 grams of iodine and 10 grams (U.S.P.) or 7.5 grams (B.P.C.) of potassium iodine per cc. of solvent; Hackhs Chemical Dictionary, Third Edition.

Example II The procedure of Example I was followed in this case excepting that the Devlex iodine complex was replaced by poly-N-vinyl-Z-oxazolidinone iodine complex having a molecular weight of approximately 150,000. The results were similar to those obtained in Example I.

I claim:

1. A light sensitive photographic material comprising a base and a light sensitive silver halide emulsion layer, said light sensitive material containing as an antifoggant the iodine complex of a compound represented by the following formula:

RGH--O N -dH-GH- 11 wherein n is an integer the value of which is sufiiciently high to produce an average molecular weight of about 150,000 and R is selected from the class consisting of hydrogen and lower alkyl.

2. The composition as defined in claim 1 wherein the said anti-foggant is located in the silver halide emulsion.

3. The article as defined in claim 1 wherein said antifoggant is located in the layer adjacent to said silver emulsion.

4. A light sensitive photographic material comprising a base with a light sensitive silver halide emulsion thereon, said emulsion containing as an antifoggant, the iodine complex of a compound represented by the following formula:

H3CCHGO H: N -(EH-CHz- 11 wherein n is a positive integer the value of which is sufficient to produce an average molecular weight of about 150,000.

5. The process of minimizing and preventing fog in light sensitive silver halide materials, comprising a base having a light sensitive silver halide emulsion thereon which comprises exposing said emulsion to a light image and developing said emulsion in the presence of the iodine complex of an antifoggant compound represented by the following general formula:

-dH-GH= 11 wherein n is an integer the value of which is sufficiently high to produce molecular weight of about 150,000 and R is selected from the class consisting of hydrogen and lower alkyl.

6. The process as defined in claim 5 wherein the antifoggant is represented by the following formula:

HsCCH-(JO JH-CHz n where n is an integer the value of which is sufliciently high to produce molecular weight of about 150,000.

No references cited.

Claims

5. THE PROCESS OF MINIMIZING AND PREVENTING FOR IN LIGHT SENSITIVE SILVER HALIDE MATERIALS, COMPRISING A BASE HAVING A LIGHT SENSTIVE SILVER HALIDE EMULSION THEREON WHICH COMPRISES EXPOSING SAID EMULSION TO A LIGHT IMAGE AND DEVELOPING SAID EMULSION IN THE PRESENCE OF THE IODINE COMPLEX OF AN ANTIFOGGANT COMPOUND REPRESENTED BY THE FOLLOWING GENERAL FORMULA: