US3573913A

US3573913A - Light-sensitive silver halide materials

Info

Publication number: US3573913A
Application number: US573832A
Authority: US
Inventors: Jozef Frans Willems; Joseph Louis De Munck
Original assignee: Agfa Gevaert NV
Current assignee: Agfa Gevaert NV
Priority date: 1965-10-07
Filing date: 1966-08-22
Publication date: 1971-04-06
Anticipated expiration: 1988-04-06
Also published as: GB1107022A; BE686518A; DE1522397A1; FR1496295A; NL6612597A

Abstract

PHOTOGRAPHIC LIGHT-SENSITIVE MATERIALS ARE DESCRIBED WHICH INCLUDE A URETHAN WHICH IS THE REACTION PRODUCT OF (1) AN ALKOXY POLYETHYLENE GLYCOL ESTER OF ISOCYANATOACETIC ACID HAVING THE FORMULA

R-O-(CH2-CH2-O)N-(CH2)2-OOC-CH2-N=CO

WHEREIN

R REPRESNETS AN ALKYL RADICAL HAVING FROM 1 TO 5 CARBON ATOMS, AND N REPRESENTS AN INTEGER OF FROM 1 TO 35, AND

AN UNSUBSTITUTED, SATURATED, ALIPHATIC ALCOHOL; OR (2) AN ISOCYANATE AND AMONO-ALKYL ETHER OF POLYOXYETHYLENE GLYCOL. THESE MATERIALS UPON DEVELOPMENT WITH A HYDROQUINONE-FORMALDEHYDE-BISULPHITE DEVELOPER ARE SUBSTANTIALLY FREE OF "PEPPERS."

Description

United States Patent US. Cl. 9666.3 15 Claims ABSTRACT OF THE DISCLOSURE Photographic light-sensitive materials are described which include a urethan which is the reaction product of (1) an alkoxy polyethylene glycol ester of isocyanatoacetic acid having the formula R represents an alkyl radical having from 1 to 5 carbon atoms, and n represents an integer of from 1 to 35, and

an unsubstituted, saturated, aliphatic alcohol; or (2) an isocyanate and a mono-alkyl ether of polyoxyethylene glycol. These materials upon development with a hydroquinone-formaldehyde-bisulphite developer are substantially free of peppers.

This invention relates to novel polyoxyalkylene derivatives, photographic materials comprising such polyoxyalkylene derivatives and to the development of exposed silver halide emulsions in the presence of these derivatives.

It is known that the development of continuous tone images by means of a hydroquinone p-methyl-aminophenol developer is accelerated under the influence of polyoxyalkylene compounds having a molecular weight preferably above 1500. When, however, such polyoxyalkylene compounds are used in combination with a formaldehydehydroquinone-bisulfite developer as known from the German Pat. No. 1,141,531 filed Jan. 24, 1962 by Perutz Photowerke G.rn.'b.H., an increase of the gradation together with a desensitisation is obtained. The latter combination is found to be very suitable for the development of light-sensitive materials suited for use in the graphic art on account of the very contrasty development obtained therewith. As light-sensitive materials for the reproduction of graphic line or screen images silver chloride and silver chlorobromide emulsions are generally employed.

The quality of a developed dot screen print is judged of by the dot sharpness. As described by J.A.C. Yule, J. Franklin Institute, vol. 239, p. 223 development of graphic materials with a hydroquinoneformaldehyde bisulphite developer easily gives rise to the formation of peppers. Peppers are black spots of a very high density which are irregularly produced during the development in the areas of the light-sensitive emulsion which are rather slightly exposed.

'Ihese peppers when they are present in a high amount are markedly degrading the quality of a screen image reproduction by deforming the screen dots and/or soiling the areas which were practically not exposed. The phenomena pepper particularly arises in the case partly aerial oxidized or rather exhausted developing baths are used. Known polyoxyalkylene compounds and derivatives used as developing accelerators greatly increase the formation of peppers.

It has been found now that the development of line and/or screen images in silver chloride and silver chlorobromide emulsions with a hydroquinone-formaldehyde bisulphite developer, which is combined with a product formed by the reaction of a mono-isocyanate containing oxyalkylene groups with an alcohol or a glycol or obtained by the reaction of a mono-isocyanate or a di-isocyanate with a monoether of a polyoxyalkylene glycol, e.g. a monoalkoxy polyoxyethylene glycol, is very contrasty, yields very sharply defined screen dots and occurs with the formation of a smaller number of peppers as is the case with known polyoxyalkylene development accelerators, and furthermore can take place within a broad interval of time without harm to the image quality. Comparative tests described furtheron prove the technical progress of developer combinations according to the present invention as compared with developer combinations with known polyoxyalkylene glycols and derivatives thereof.

Products which can 'be used according to the present invention are more particularly:

(a) urethans formed by allowing to react an alkoxy polyethylene glycol ester of isocyanato-acetic acid corresponding to the following formula:

R represents an alkyl radical preferably having 1 to 5 carbon atoms, and

n represents a positive integer from 1 to 35, preferably from 8 to 20,

with alcohols such as methanol, ethanol, propanol, hexadecylol, or with polyols such as ethylene glycol, glycerol etc.

(b) bisurethans formed by reaction of diisocyanates such as 2,5-diisocyanato-toluene or 1,6-diisocyanato-n-hexane with polyoxyethylene glycol ethers having a molecular weight preferably comprised between and 1000, in which one of the terminal hydroxyl groups is rendered non-reactive in respect of isocyanato groups e.g. by etherification with an alcohol having preferably 1 to 5 carbon atoms.

By way of illustration the preparation of some monoand diurethan polyoxyalkylene compounds according to the present invention will now be described. As will be appreciated, mixtures of the monoand di-urethan polyoxyalkylene compounds may be formed depending upon the proportions of the reactants.

PREPARATION 1 Urethan formed from ethanol and a methoxy polyethylene glycol isocyanato-acetate.

(a) Methoxy polyethylene glycol bromo-acetate 147 g. (0.2 mole) of methoxy polyethylene glycol (average molecular weight 750) are dissolved in 500 ccs. of benzene and 31.5 g. (0.2 mole) of bromoacetyl chloride are added to this solution whilst stirring. A nitrogen flux is conducted through the reaction mixture for eliminating the evolving hydrochloride. The reaction mixture is heated to 60 C. and boiled for 2 hours in order to eliminate all of the hydrogen chloride. Subsequently the benzene is distilled off and the residue is utilised for the preparation of:

(b) Methoxy polyethylene glycol isocyanato-acetate 1779 g. of methoxy polyethylene glycol bromo-acetate are dissolved in 4.5 litres of anhydrous ether and 162 g. of finely divided potassium isocyanate are added whilst stirring. The reaction mixture is refluxed for 40 hours. An amount of 162 g. of potassium isocyanate is added yet and refluxing is continued for 24 hours. After having been cooled, the ether layer is separated as completely as pos- 3 sible. The remaining reaction mixture is diluted with 5 litres of benzene. The precipitated potassium bromide is filtered off and the benzene filtrate is evaporated in vacuo. The residue is dried in vacuo.

CH3O(CHzCH2O)mO O CHzNI-IO OOC2H5 PREPARATION 2 Urethan formed from n-hexadecylol and methoxy polyethylene glycol isocyanato-acetate.

CH O-(CH CH O) COCH NHCOOC H -n 25 g. (0.03 mole) of methoxy polyethylene glycol isocyanato-acetate prepared as described in Preparation 1 (b) are dissolved in 100 ccs. of anhydrous benzene. Then 7.3

4 PREPARATION 5 Diurethan formed from polyethylene glycol with an average molecular weight of 1000 and methoxy polyethylene glycol isocyanato-acetate (3H2 (IJH $0 ('30 (OCI-IzCHz)raOCHa (O CHzOHzlmOCHa 25 g. (0.03 mole) of methoxy polyethylene glycol isocyanato acetate are dissolved in 100 ccs. anhydrous ben zene. Then g. of polyethylene glycol with an average molecular weight of 1000 are added and the mixture is refluxed for 2 hours on a water bath. The benzene is distilled off in vacuo. Yield: 48.5 g.

PREPARATION 6 Diurethan formed from methoxy polyethylene glycol and 2,S-diisocyanato-toluene.

150 g. (0.2 mole) of methoxy polyethylene glycol with an average molecular Weight of 750 are dissolved in 150 ccs. of anhydrous benzene. Then 17.4 g. (0.1 mole) of 2,5-diisocyanato-toluene dissolved in 50 ccs. of benzene are added. The temperature of the reaction mixture is maintained between 27 and 30 C. by cooling with ice- Water till the exothermic reaction is terminated. The reaction mixture is refluxed for another 105 minutes. The benzene is distilled off in vacuo on a Water bath at 50 C.

Yield: 155 g.

The total reaction is as follows:

no 0 omo onomo-nwmornon -om the O lTIHCOOCHzCHg (OCHzCHz) 5-OCHa g. of n-hexadecylol are added and the reaction mixture is refluxed for 2 hours on a water bath. Subsequently the benzene is distilled off in vacuo. Yield: 30.5 g.

PREPARATION 3 Diurethan formed from ethylene glycol and methoxy polyethylene glycol isocyanato-acetate.

OHQO (CH2CH20)10COCHzNHCOOfiIHz CHaO(CH2CH2O)mCOGHzNHOOO-CHz 25 g. (0.03 mole) of methoxy polyethylene glycol isocyanato-acetate prepared as described in Preparation 1 (b) are dissolved in 100 ccs. of anhydrous benzene. Then 18 g. of ethylene glycol are added and the reaction mixture is refluxed for 2 hours on a Water bath. The benzene is distilled off in vacuo. Yield: 23.5 g.

PREPARATION 4 Diurethan formed from polyethylene glycol with an average molecular weight of 300 and methoxy polyethylene glycol isocyanato-acetate 25 g. (0.03 mole) of methoxy polyethylene glycol isocyanato-acetate are dissolved in 100 ccs. of anhydrous benzene. Then 9 g. of polyethylene glycol with an average molecular weight of 300 are added and the resulting mixture is refluxed for 2 hours on a water bath. The benzene is distilled oif in vacuo. Yield: 31 g.

PREPARATION 7 Diurethan of methoxy polyethylene glycol and 1,6-di isocyanato-hexane.

150 g. (0.2 mole) of methoxy polyethylene glycol with an average molecular weight of 750 are dissolved in 150 ccs. of anhydrous benzene. Then a solution is added of 16.8 g. (0.1 mole) of 1,6-diisocyanato-hexane in 50 ccs. of anhydrous benzene. The reaction mixture is refluxed for min. The benzene is distilled 0E in vacuo on a water bath at 50 C. Yield: 166 g.

The urethans used according to the present invention can be added to the silver halide emulsions or can be incorporated into a water-permeable layer under or on top of the emulsion layer, which Water-permeable layer stand in water-permeable relationship with the emulsion layer.

Preferably the said products are added to the lightsensitive silver halide emulsions in dissolved form in water or a mixture of water and water-miscible organic solvents, which do not impair the photographic characteristics of the emulsion.

However, these products can also be incorporated into the emulsion by imbibition by treating it with a solution containing these products or by diffusion from an adjacent Water-permeable layer comprising these products.

The water-soluble urethans used according to the present invention can be added to the light-sensitive silver halide emulsion during different preparation steps of the light-sensitive material. For example they can be incorporated therein by a separate addition or they can be added as a mixture with one or more ingredients used in the formation of the silver halide grains, during the physical or chemical ripening or during another step preceding the coating of the emulsion.

The said products are preferably added to the emulsion after the chemical ripening and just before the coating of the emulsion.

The optimun amount of the urethans to be added to the emulsion depends on the very compound, on the nature of the colloid binder of the silver halide grains and on the amount and type of silver halide in the emulsion. In general, however, the above urethan products are added to the light-sensitive material in an amount of 1 mg. to 10 g. per mole of silver halide. When incorporated into the developer they are used in amounts ranging from 50 mg. to 20 g. per litre of developer. If necessary, amounts exceeding these limits can be used as well.

The increase of the dot defininition and development latitude obtained with urethan products according to the present invention can be combined with a chemical sensitisation by using in combination with the abovementioned urethan products chemical sensitising agents such as sulphur-containing compounds e.g. allyl isothio cyanate, allyl thiourea or sodium thiosulphate, reducing agents such as the tin compounds described in the Belgian patent specifications 493,464, filed Jan. 24, 1950 and 568,687, filed June 18, 1958 by Gevaert Photo-Producten N.V., the imino-amino methane sulphinic acid compounds described in the British patent specification 789,823, filed Apr. 29, 1955 by Gevaert Photo-Producten N.V. or precious metal compounds such as gold, platinum, palladium, iridium, ruthenium and rhodium compounds. The sensitising action also manifests itself, of course, when combing the above-mentioned urethan products with the sensitising compounds present by nature in gelatin.

The urethan products according to the present invention can also be used in combination with stabilising agents for silver halide emulsions, such as mercury compounds and the compounds described in the Belgian patent specifications 571,916 and 571,917, filed Oct. 10, 1958 by Gevaert Photo-Producten N.V., and in combination with sensitising and stabilising cadmium salts in the lightsensitive material as well as in the developer.

Water-soluble compounds, which also accelerate the development, such as those described e.g. in the British patent specification 954,205, filed June 30, 1960 by Gevaert Photo-Producten N.V. can be applied together with the urethans according to the present invention in a developing bath as well as in the light-sensitive material.

Together with the above-mentioned urethan products, derivatives of tetra-azaindenes having the following general formula can be used as fog-inhibiting compounds:

wherein each of R and R represents a hydrogen atom, an alkyl,

an aralkyl, or an aryl radical, and

R represents a hydrogen atom, an alkyl, a carboxy or an alkoxy carbonyl group.

Such compounds can be prepared shtarting from 1 mole of fl-ketoester or a a-ethoxymethylene-B-ketoester with 1 mole of a suitable 3-amino-1,2,4-triazole. By way of example of such derivatives 5-methyl-7-hydroxy-s-triazolo- (l,5-a)-pyrimidine can be mentioned.

Other agents such as hardening agents, wetting agents, plasticisers, developing agents, and optical sensitising agents can be incorporated into the emulsion in the usual way.

The urethans according to the present invention can preferably be used in the development of screen prints on silver chloride and silver bromo-chloride emulsions with a hydroquinone-formaldehyde-bisulphite developer, but they can also be used in combination with silver halide emulsions of any other type.

The following examples illustrate the invention.

EXAMPLE 1 After ripening of a green-sensitised silver chlorobromide emulsion (35 mole percent of bromide) containing 5-methyl-7-hydroxy-s-triazolo-( l,5-a)-pyrimidine and cadmium chloride, a polyoxyalkylene derivative listed in the following Table 1 is added. After the addition of the usual wetting agent, of 25% by weight of a latex-plasticiser calculated on the weight of gelatin, and of a hardening agent such as formaldehyde and glyoxal, the emulsion samples are coated in the same way on a cellulose triacetate support and dried.

The latex-plasticiser consists in a latex of a 20% by weight aqueous dispersion of poly(ethyl acrylate) prepared according to known techniques of emulsion polymerisation carrying out the polymerisation in the presence of 8% by weight calculated on the monomer of an emulsifying agent of one of the following types: the condensation product of oleic acid and methyltaurine, the sodium salt of l-aurylsulphonic acid or the sodium salt of an alkylbenzene sulphonic acid wherein the alkyl radical contains from 8 to 12 carbon atoms.

The light-sensitive material is exposed through a continuous wedge and a glass screen by means of a lightsource having a colour temperature of 37CO K. The exposure is regulated such that the wedge print of the screen embraces the beginning of dot formation as well as the disappearance of the high lights.

The development is performed at 20 C. in a developing bath having the following composition:

Water to 1000 ccs.

The appreciation of the dot definition occurs visually by comparison with standard materials, which in decreasing order of dot definition quality are indicated with the numbers 1, 2, 3 and 4.

The appreciation of the peppers occurs visually after exposure of the light-sensitive materials through a step wedge and without screen and development for 2.5 min. at 20 C. in the above-mentioned developer, which previously has been deactivated, by developing therein 0.32 sq. m. of completely exposed graphic film per liter.

The numbers 0 to 4 represent the number of peppers:

0=no peppers 1=very few 2=few 3=many (material no longer suitable for reproduction) 4=very much (useless material).

TABLE 1 D 01: definition after a development time of-- Mg. of oxyalkylenc condensation product per mole of silver halide Pep- 3 min. pers 2 min.

7 EXAMPLE 2 Example 1 is repeated with a similar type of emulsion but the polyoxyalkylene derivatives stated in Table 2 are used.

TABLE 2 Dot sharpness after a development time of- Mg. of oxyalkylene condensation product Pepper mole of silver halide 3 min. 3.5 min. pers 100 mg. of the condensation product of 1 mole of maleic anhydride and 1 mole of polyethylene glycol having an average molecular Weight of 2,000 prepared in an analogous way to preparation 3 of the British patent specification 920,637 filed May 7, 1959 by Gevaert Photo'Producten N.V 1 1 2. 5 140 mg. of the condensation product according to preparation 3 1 1 0. 9

EXAMPLE 3 Example 1 is repeated with the same emulsion type, but the polyoxyalkylene derivatives listed in Table 3 are used.

TABLE 3 Dot definition after a developing time oi Mg. of oxyalkylene condensation Pepproduct per mole of silver halide 2.5 min. 3 min. 3.5 min. pers 30 mg. oi the condensation product according to preparation 3 1 2 1. 40 mg. of the condensation product according to preparation 1 2 1 0 R represents an alkyl radical having from 1 to carbon atoms, and n represents an integer of from 1 to 35 and an unsubstituted, saturated, aliphatic mono, di or trihydric alcohol or polyethylene glycol; or (2) a monoor di-isocyanate and a mono-alkyl ether of a polyoxyethylene glycol having a molecular weight of from about 100 to 1,000, said alkyl being from 15 carbon atoms.

2. The light-sensitive material of claim 1 wherein the alcohol is an alcohol having only one hydroxy group.

3. The light-sensitive material of claim 1 wherein the alcohol is a polyol.

4. The light-sensitive material of claim 1 wherein the isocyanate is a mono-isocyanate.

5. The light-sensitive material of claim 1 wherein the isocyanate is a di-isocyanate.

6. The light-sensitive material of claim 1 wherein said emulsion layer includes silver chloride or silver chlorobromide and said urethan is reaction product (1).

7. The light-sensitive material of claim 1 wherein said emulsion layer includes silver chloride or silver chlorobromide and said urethan is the reaction product (2).

8. The light-sensitive material of claim 1 wherein said urethan is present in an amount of from 100 milligrams to 100 grams per mole of silver halide.

9. A photographic hydroquinone-formaldehyde-bi-sulphi-te developer containing a monoor (ii-urethan which is 8. the non-polymeric reaction product of (1) an alkoxy polyethylene glycol ester of isocyanato-acetic acid having the formula wherein:

R represents an alkyl radical having fro 1 to 5 carbon atoms, and

n represents an integer of from 1 to 35 and an unsubstituted, saturated, aliphatic mono, di or trihydric alcohol or polyethylene glycol; or (2) a monoor di-isocyanate and a mono-alkyl ether of polyoxyethylene glycol having a molecular weight of from about to 1,000, said alkyl being from 1-5 carbon atoms.

10. The developer of claim 9 wherein urethan is present in an amount of from 50 milligrams to 20 grams per litre.

11. A process for developing photographic materials containing a light-sensitive silver halide in which a photographic silver chloride or silver chlorobromide emulsion sutable for the production of line and screen prints is developed with a hydroquinone-formaldehyde-bisulphite developer characterized in that the development is carried out in the presence of a monoor di-urethan which is the non-polymeric reaction product of (1) an alkoxy polyethylene glycol ester of isocyanate-acetic acid having the formula R represents an alkyl radical having from 1 to 5 carbon atoms, and n represents an integer of from 1 to 35 and an unsubstituted, saturated, aliphatic mono, di, or trihydric alcohol or polyethylene glycol; or (2) a monoor di-isocyanate and a mono-alkyl ether of a polyoxyethylene glycol having a molecular weight of from about 100 to 1,000, said alkyl being from 1-5 carbon atoms. 12. The process of claim 11 wherein the alcohol is an alcohol having only one hydroxy group.

13. The process of claim 11 wherein the alcohol is a polyol.

14. The process of claim 11 wherein the development is carried out in the presence of reaction product (1).

15. The process of claim 11 wherein said urethan is reaction product (2).

References Cited UNITED STATES PATENTS 3,030,209 4/1962 Henn 9666.3 3,038,804 6/ 1962 Knox 96- 107 3,150,977 9/1964 Hart 96107 3,158,484 11/1964 Williams 96-114 3,158,484 11/1964 Willems 96--114 3,307,948 3/1967 Thiers 96--66.3 2,531,832 11/1950 Stanton 9666.3

FOREIGN PATENTS 1,122,834 11/1962 Germany. 1,305,017 8/1962 France.

NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner U.S. Cl. X.R. 9695, 107