US3443951A - Photographic light-sensitive materials containing phosphoric acid ester of aliphatic polyols - Google Patents

Description

United States Patent i 3,443,951 PHOTOGRAPHIC LIGHT-SENSITIVE MATERIALS CONTAINING PHOSPHORIC ACID ESTER OF ALIPHATIC POLYOLS Jozef Willems, Wilrijk-Antwerp, Edwin Frans Hendricx, Boechout, Robrecht Julius Thiers, Brasschaat, and Jozef Jan Onghena, Heverlee, Belgium, assignors to Gevaert- Agfa N.V., Mortsel, Belgium, a Belgian company No Drawing. Filed June 30, 1965, Ser. No. 468,614 Claims priority, application Great Britain, July 2, 1964, 27,346/ 64 Int. Cl. G03c 1/34 U.S. CI. 96-94 7 Claims ABSTRACT OF THE DISCLOSURE The formation of spots in radiation-sensitive silver halide material due to the presence of particles of heavy metals, compounds of heavy metals and the corrosion products of such metals or the compounds inhibited by the incorporation in the material of at least one watersoluble phosphoric acid ester of an aliphatic polyol, which per molecule contains at least two phosphoric acid groups from the class of the primary and secondary phosphoric acid groups. Preferably, the polyol is an aliphatic hydrocarbon polyol.

This invention relates to photographic light-sensitive silver halide materials containing compounds which prevent the formation of spots by the presence of particles of heavy metals and/or heavy metal compounds.

Although an utmost care is taken in the manufacture of light-sensitive material, it is diflicult to avoid completely the setting down of particles of heavy metals, such as iron particles, or of compounds of heavy metals, such as rust particles, onto the light-sensitive material. Said particles generally originate from the wearing and the corrosion of the coating machines, but also traces of these metals or metal compounds are sometimes present in the photochemicals used or may be present in the support such as a support of paper, film and glass upon which the light-senstive emulsion is coated.

Said metal particles or particles of metal compounds are harmful particularly because they are chemically reactive, which means that they exert a secondary action upon the light-sensitive emulsion layer and aggravate the faults which are caused by the presence of said particles and which are mostly invisible by the unaided eye in such a way that according to the nature of the particle and the kind of the emulsion applied, light and dark spots become visible after treating the exposed lightsensitive material in the photographic baths.

The metal particles in the photographic layers can be affected and the corrosion products formed can diffuse away from the central nucleus. These corrosion products can exert a sensitizing or descnsitizing action on the emulsion so that after the normal bath-treatment the photographic material shows black and white spots respectively. Furthermore most of these metals or their compounds can act as reductors and cause a spontaneous development which leads to black spots. On the contrary, other influences such as affection of the latent image and hindrance of the development lead to white spots. In

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all these cases the resulting spot is always larger than the dust particle which is the cause of this undesired phenomenon. This can easily be checked, e.g., by bleaching out with a usual bleaching agent the silver from the material showing the black spot. Nearly always the black spot disappears but in the centre a very small nucleus remains which can only be seen by enlarging.

Also fine metal particles or dust consisting of metal compounds which are present in a nonlight-sensitive adjacent layer exert an equally disadvantageous influence on the upperor underlying light-sensitive layer. The harmful corrosion products of the metal particles or the dissolved ingredients of the metal compounds indeed can reach by diffusion the light-sensitive layer to cause the above-mentioned faults.

Hitherto many compounds have already been proposed to prevent this formation of spots or at least to reduce such formation to a great extent. All these compounds, however, show one or more of the following disadvantages: an insufficient activity, an activity only in determined emulsions and in a well determined rather small pH range, and the occasioning of secondary effects on the silver halide emulsion layer such as desensitisation, fog formation and colouration. Also the phosphoric acid derivatives proposed as spot inhibiting compounds show these disadvantages. The phosphoric acid derivatives proposed hitherto are mainly alkali metaphosphates, alkali tripolyphosphates and alkali hexametaphosphates either or not mixed with alkali pyrophosphates. The primary and secondary alkylor aryl-phosphates and acid alkylor aryl-pyrophosphates incorporated into the light-sensitive silver halide material do not even show any spotinhibiting action at all.

In the circumstances, it was very surprising to state that the formation of spots can practically completely be avoided when in at least one Water-permeable layer lying at the same side of the support as the light-sensitive silver halide emulsion layer and/or in the support itself, at least one water-soluble phosphoric acid ester of an aliphatic polyol is present which contains per molecule at least two phosphoric acid groups from the class of the primary and secondary phosphoric acid groups. These primary and secondary phosphoric acid groups can likewise be present in their salt form such as sodium, potassium or "ammonium salts or as amines.

These phosphoric acid esters are active in all kinds of light-sensitive silver halide materials regardless of the pH and the sensitivity of the silver halide emulsion layer; moreover, they also appear to exert an antistatic and fog-depressing action on the light-sensitive material.

The phosphoric acid esters used according to the present invention can be prepared in different ways. It is necessary during this preparation to choose the mutual molar proportions of the reagents in such a way that always two or more primary or secondary phosphoric acid groups are introduced per molecule of aliphatic polyol. It can be determined in a simple way by potentiometric titration of the said functions present whether this has occurred.

A first method of preparation is the reaction of aliphatic polyols with phosphorus pentoxide. Herein mixtures of different compounds are formed which contain primary and/or secondary phosphoric acid groups. Moreover, polyphosphate structures are built as well.

There is also the possibility that when two hydroxyl functions are in favourable position, cyclic phosphoric acid esters are formed.

Appropriate phosphoric acid esters can also be prepared by phosphorylation of aliphatic polyols with phosphorus oxychloride followed by hydrolysis of the acid chloride formed as an intermediate product.

Other processes for the preparation of appropriate phosphoric acid esters are transesterification reactions for instance of monoalkyl phosphates with aliphatic polyols.

Also A. J. Kirby (Chem. and Ind. 47 (1963), 1877), describes a process for the preparation of phosphoric acid esters which are appropriate for being applied according to the present invention, viz., a reaction of phosphorous acid and iodine with polyols.

Aliphatic polyols which are appropriate for the preparation of the said phosphoric acid esters are among others carbohydrates such as glucose, mannitol, sorbitol, glycerine, 1,4-butanediol, 1,2,4-butanetriol 1,2,6-hexanetriol, pentaerythritol, 2,4-dihydroxy-3-(hydroxymethyl)- pentane, 1,1,l-tris(hydroxymethy1)-propane and 4-hydroxy-2- (hydroxymethyl)-n-amy1 alcohol.

The compounds used according to the present invention can be present in difierent concentrations in the support, e.g., a paper support of the light-sensitive material and/ or in at least one of the water-permeable layers lying at the same side of the support as the light-sensitive silver halide emulsion layer. Said concentrations depend among others on the compound chosen and the nature of the layer wherein the compound is present. Preferably the compounds according to the present invention are present in the light-sensitive silver halide emulsion layer itself and this in the most widely varying concentrations ranging from some mg. to and more g. per sq. m. of light-sensitive material. For the case the compounds are not present in the light-sensitive layer but in another layer, they are nevertheless active since they dilfuse into said light-sensitive layer.

The phosphoric acid esters according to the present invention usually are first dissolved, e.g., in water. The support can then be soaked with such solution for the case that the compounds applied according to the present invention are incorporated into the support. If, however, the compounds are incorporated into a waterpermeable layer, in most cases their solution is added to the coating composition of the respective layer or layers.

In a photographic material, the compounds used according to the present invention have the advantage that they do not impair at all the pursued photographic properties, such as, e.g., contrast, sensitivity and stability. Consequently, these compounds can be incorporated into high-sensitive as well as into low-sensitive emulsions, into high-contrast as well as into low-contrast emulsions, into acid as well as into alkaline emulsions.

A further advantage is that the compounds according to the invention do not impair at all the other products used in the manufacture of light-sensitive materials such as dispersing agents, colour couplers, surface-active agents, optical bleaching agents, antioxidising agents, sensitisers, fog-inhibiting agents, stabilisers, hardeners or plasticisers.

As a result, the compounds according to this invention can be used in all kinds of photographic negative and positive material, such as, e.g., printing material, X- ray film, graphic material, infrared-sensitive silver halide material and material for the application of the silver complex diffusion transfer process. Also in photographic light-sensitive material not containing silver halide, or in photographic nonlight-sensitive material the phosphoric acid esters described can successfully he used for avoiding spots caused by particles of heavy metal compounds.

The following preparations and examples illustrate the present invention.

4 PRODUCT l.REACTION PRODUCT OF SORBI- TOL AND PHOSPHORUS PENTOXIDE A mixture of g. (0.42 mol) of phosphorus pentoxide, 91 g. (0.47 mol) or anhydrous sorbitol and 500 cc. of diethyl ether is refluxed for 7 h. on a water bath, whilst stirring. After standing overnight, the white crystalline reaction product is sucked oil. Yield: 150 g. The reaction product is hygroscospic and an aqueous solution thereof reacts as a strong acid.

PRODUCT 2.REACTION PRODUCT OF SORBITOL AND (MONO)ETHYLDIHYDROGEN PHOS- PHATE: SORBITOL HEXAKIS(DIHYDROGEN) PHOSPHATE 151 mg. (1.14 mols) of (mono)ethyldihydrogen phosphate, 18.2 g. (0.09 mol) of sorbitol and a little magnesium powder are heated in a flask on an oil bath, whilst the reaction mass is stirred under nitrogen. The theoretically calculated amount of ethanol is distilled 01f. Meanwhile the temperature of the oil bath has been increased to 200 C. The excess of (mono)ethyldihydrogen phosphate is removed by washing the reaction mass with anhydrous diethyl ether. The residue is placed under vacuum on a boiling water bath and thereafter cooled down to room temperature and dissolved in methanol. This solution is filtered over active carbon, and the methanol is distilled off under reduced pressure on a water 'bath at 40 to 50 C. Yield: 42.5 g. The reaction product is a viscous oil which reacts as an acid.

PRODUCT 3.REACTION PRODUCT OF GLYC- ERINE AND PHOSPHORUS PENTOXIDE 276 g. (2.82 mols) of dried glycerin are added in 3 times to a mixture of 59 g. (0.42 mol) of phosphorus pentoxide in 500 cc. of anhydrous diethyl ether at 150 C. The reaction is relatively exothermic. After adding all glycerine and refluxing for 2 h. on the water bath, the diethyl ether is decanted and the reaction product obtained is dried under vacuum. Yield: 320 g. The reaction product is a viscous oil which reacts as a strong acid.

PRODUCT 4.--REACTION PRODUCT OF GLUCOSE AND PHOSPHORUS PENTOXIDE A mixture of 50 g. (0.35 mol) of phosphorus pentoxide, g. (0.47 mol) of glucose and 500 cc. of diethyl ether is refluxed for 7 h. in a flask on a water bath, whilst thoroughly stirring. After standing overnight, the reaction product is sucked off. Yield: 138 g. The reaction product is hygroscopic and an aqueous solution thereof reacts as a strong acid.

PRODUCT 5.3,9 DIHYDROXY 2,4,8,l0 TETRA OXA-3,9-DIPHOSPHASPIRO[5,5+UNDECANE-3,9- DIOXIDE /OCH: CHzO\ R /i O OCH: OHaO O This product is prepared as described in J. Org. Chem. 28 (1963), 1608-1612.

PRODUCT 6.-PENTAERYTHRITOL TETRAKIS (DI-HYDROGEN PHOSPHATE) HO (T) (T) OH P-OCH: CHaOP HO OH HO OH P-O CH: CH:OP

l.\ HO O O OH This product is prepared as described in the U.S. patent specification 2,583,549, filed Apr. 25, 1950, by G. C. Daul and I. R. Reid.

Example 1 A not yet quite dry adhesive layer applied to a cellulose triacetate support, is dusted with finely divided iron powder. A strip A of this treated support is coated with a high-sensitive panchromatically sensitized silver bromide emulsion. A strip B of this treated support is coated with the same silver bromide emulsion to which, however, per kg. of emulsion 1 g. of product 1 was added. After driving these two test strips are exposed in such a way that after developing for 9 min. at room temperature, fixing and rinsing, a density of 0.6 is obtained. For development a solution of the following composition is used:

Water 800 Monomethyl-p-aminophenol sulphate g 2 Sodium sulphite (cryst.) g 200 Hydroquinone g 4 Borax g 2 Water to 1000 cc.

After development, both strips A and B are rinsed for some seconds and then fixed for min. in a solution of the following composition:

Sodium thiosulphate g 200 Potassium metabisulphite g 25 Water to 1000 cc.

The strips are then rised for 30 minutes in running water and finally dried. The strips A shows numerous black spots whereas the strip B prepared according to the invention shows a uniform appearance and the same density all over its surface.

Eample 2 Example 1 is repeated but instead of adding product 1 to the emulsion ready for coating, a same amount of product 3 is added thereto.

Example 3 A strip of crude paper A is coated with a barytalayer of the following composition:

50% aqueous barium sulphate suspension kg 2 10% aqueous gelatin solution cc 1000 Very finely divided metal powder, originating from the coating machine g 0.5

Water cc 800 Monomethyl-p-aminophenol sulphate g 1.5 Sodium sulphite (cryst.) g 50 Hydroquinone g 6 Sodium carbonate (cryst.) g 100 Potassium bromide g 1 Water to 1000 cc.

After rinsing for 5 sec., fixing for 10 min. in a solution as described in Example 1, rinsing for 1 hour in running water, and drying, the developed paper strip A displays numerous white spots each showing in the center the applied metal particle, whereas the strip B prepared according to the invention shows a uniform appearance and has the same density all over its surface.

Example 4 A strip of baryta-coated paper A is prepared as in Example 3. A strip B is prepared in the same way with the same baryta composition to which, however, per kg. 5 g. of product 5 were added. Both baryta-coated strips are coated with a silver chlorobromide emulsion which on development gives a warm brown image tone. After developing, fixing and rinsing as in Example 3, numerous white spots are observed on the paper strip A, whereas the strip B prepared according to the invention shows a uniform appearance and possesses the same density all over its surface.

Example 5 A strip of crude photographic paper is coated with a baryta layer of the following composition:

50% aqueous barium sulphate suspension kg 2 10% aqueous gelatin solution cc 1000 The half A of this baryta-coated strip is coated with a light-sensitive contrasty silver bromide emulsion which contains iron powder. After drying, this strip is exposed in such a way that after developing for seconds, fixing and rinsing it shows a density of 0.6 For development a solution is used as that described in Example 3. The paper strip is rinsed for 5 sec., fixed for 10 min. in a solution as described in Eample 1, rinsed for 1 hour in running water and dried. The paper strip shows numerous white spots.

If to the light-sensitive emulsion, however, 3 g. of product 6 are added per kg. and if this emulsion is then coated on the half B of the baryta-coated strip the latter shows after a further treatment as for the half A a uniform appearance without white spots.

Example 6 Example 5 is repeated but product 6 is replaced by 4 g. of product 1.

Example 7 Example 5 is repeated but product 6 is replaced by 4 g. of product 2.

Example 8 Example 5 is repeated but product 6 is replaced by 4 g. of product 3.

Example 9 Example 5 is repeated but product 6 is replaced by 4 g. of product 4.

Example 10 Example 5 is repeated but product 6 is replaced by 4 g. of product 5.

We claim:

1. Photographic silver halide material sensitive to electromagnetic radiation comprising a support and a silver halide layer thereon, said material having incorporated therein at least one water-soluble phosphoric acid ester of an aliphatic polyol, which per molecule contains at least two phosphoric acid groups from the class of the primary and secondary phosphoric acid groups, said acid groups being in the form of the free acid or the water-soluble salts thereof.

2. Photographic light-sensitive silver halide material according to claim 1, wherein the water-soluble phosphoric acid ester is present in the light-sensitive silver halide emulsion layer.

3. The material of claim 1 wherein said polyol is an aliphatic hydrocarbon polyol.

4. The material of claim 1 including at least one waterpermeable layer in water-permeable relationship with said halide layer on the same side of the support as said halide layer, said phosphoric acid ester being present in said water-permeable layer.

5. The method of inhibiting the formation in silver halide material sensitive to electromagnetic radiation of spots caused by the presence of particles of heavy metals, compounds of heavy metals and the corrosion products thereof which comprises the step of incorporating in said material at least one water-soluble phosphoric acid ester of an aliphatic polyol, which per molecule contains at least two phosphoric acid groups from the class of the primary and secondary phosphoric acid groups, said acid groups being in the form of the free acid or the water-soluble salts thereof.

6. The method according to claim 5, wherein the Watersoluble phosphoric acid ester is present in the light-sensitive silver halide emulsion layer itself.

aliphatic hydrocarbon polyol.

References Cited UNITED STATES PATENTS 3,169,863 2/1965 Grabhofer et al 96-107 3,258,338 6/ 1966 Claeys et a1. 96-94 3,332,777 7/1967 Groh-Molnar 96-94 I. TRAVIS BROWN, Primary Examiner.

US. Cl. X.R. 96-85, 87, 109