US2886437A

US2886437A - Photographic emulsions sensitized with alkylene oxide polymers and quaternary ammonium compounds

Info

Publication number: US2886437A
Application number: US550495A
Authority: US
Inventors: Douglas E Piper
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1955-12-01
Filing date: 1955-12-01
Publication date: 1959-05-12
Anticipated expiration: 1976-05-12
Also published as: GB871801A; BE553031A; DE1048146B; FR1170223A

Description

2,886,437 f Patented- May-1'2, 1959"- PHOTOGRAPHIC EMULSIONS SENSITIZEDWITH- ALKYLENE OXIDE POLYMERS 'AND QUATER- NARYAMMONIUM COMPOUNDSN-x Douglas E. Piper, Rochester, N.Y., assignor .to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey ,3

No Drawing, Application December 11, 19 55 Serial him-550,495 ,1 q 20 Claims. (Cl. 96-66) This application relates to photography and particularly to sensitizing photographic emulsions.

' It is well known that silver halide emulsions may be chemically sensitized-with a variety of materials in order to increase the speed and generally the .gamma of the emulsion, as opposed to optical sensitization in which the 2,334,864 describe .the'chemical sensitization ofsilver halide emulsions with quaternary ammonium compounds.

I have.now found that the light-sensitivity of sil-J ver halide. emulsions which have been sensitized with alkylene oxide polymers not containing a quaternary ainmonium group, with and without optical sensitizing dyes, may be further increased by the use of quaternary ammonium compounds, and that this increase in sensitivity is'not accompanied by an increase in graininess. polyalkylene oxide polymers and quaternary ammonium compounds can be used in combination in several ways to produce sensitivity increases, i.e., the compounds may be added-to the emulsion, the emulsion may be tr eated with the compounds before exposure and development, or

by the addition of at least one of the compounds to the developer. Thus it is possible to produce the sensitivity increases by using one ofthe above procedures for both compounds (e.g., adding both to the emulsion before coating) or by using the compounds in different procedures (e.g., adding the polyethylene oxide to the emulsion and the quaternary ammonium salt to the developer), as which is m advantageously employed varies with the illustrated by the examples hereinafter.

The quaternary ammonium silver halide sensitizing agents useful in the invention in conjunction with the alkylene oxide polymers include a wide variety of well known quaternary ammonium salts such as disclosed in U.S. Patents 2,288,226 and 2,271,623. 7

An important group of these salts arefthe tetraalkyl quaternary ammonium salts having thegeneral formula in which X is an anion or acid radical, for example, halide, p-toluene sulfonate, alkyl sulfate or perchlorate, R, R R and R are alkyl groups of which at least one has a chain of seven or more atoms such as carbon atoms, carbon atoms plus oxygen atoms, sulfur atoms'or nitrogen atoms and ring systems, while the remaining R groups are alkyl such as methyl, ethyl, butyl, and benzyl as exemplified hereinafter.

The

- Anotherv group of the quaternary ammonium salts',.-in which the quaternary nitrogen atom is a part-of a ring system, has the general formula where X is as above and R represents a chain of at least seven atoms such asiabove; however; R may be an aralkyl group as small as fi-phenyl'ethyl, and Z represents the atoms necessary'to complete'a cyclic structure such as {a pyridyl, a-picolyl, piperidyl or m'orpholinyl nucleus. If R contains-a second quaternary nitrogen atom, a long chain may link the nitrogen atoms as in the bis-quaternary ammonium compounds tabulated hereinafterq i Examples of the quaternary ammonium salt sensitizers are'given in the following table, the compound number for each salt being'th'at utilized in the emulsion examples hereinafter. I

CompoundNoJ l um perchlorate) Quat. IILaurylpyridinium perchlorate Quat. III' Decamethylene bis (oxymethyl apicolinium perchlorate) ,Quat. IV p-Xylylene-bis-(pyridinium perchlorate):

Quat. VHexamethylene bis(oxymethylpyridinium perchlorate) p a j Quat. VIHexadecylpyridinium bromide vQuat. VII--Decamethylene bis(oxymethyldimetbylbenzylammoniumperchlorate) Quat. VIIl- Decamethylene bis(N methylpiperi-' dinium perchlorate) Quat. IXLauryl pyridinium-p-toluen sulfonate Quat. X N n tetradecyl N methylmorpholinium-p-toluene sul'fonate Quat. XI-Lauryl trimethylammonium-p-toluene sul- .fonate v Quat. XII-n -.Myristy1 trimethylammonium ptoluene sulfonate Quat. XIII Decamethylene .bis trimethylammoniumbromide a Quat..XIV,----Deeamethylene bis trieth-ylammonium perchlorate I l e Quat. XIVa Tetradecamethylene bis (pyridiniutn perchlorate) t l These quaternary ammonium compounds can'be obt'ain ed by the methods described in the above patents.

The. quantity of quaternary ammonium compound nature ofthe'quaternary. ammonium compound and with the nature-of the emulsion. Ordinarily, the most advantageous concentration has been found to be between about 50 mgs. and 5000 mgs. of the quaternary ammonium com- A pound per gram 'mole of silver halide in the emulsion,

although greater or smaller concentrations can be employed. We have found that excesses of the quaternary ammonium compound are to be avoidedsince excesses produce fog in the emulsions. The optimum range of concentration for any quaternary ammonium compound described hereinis ordinarily fairly narrow and can best be determined by employing a series 'of'concentrations of the quaternary ammonium compound separately in several batches of the same emulsion and determining the sensitivity of the several batches before and after incorporation of the quaternary, ammonium compound, in the usual-manner which is,'of course, 'well'known to those skilled in the'art. i '1 I The alkylene oxide polymers used to sensitize the l emulsions may be of various types. The alkylene oxides from which the polymers are derived contain from 2 to 4 carbonatoms, e.g.,.ethylene oxide, propylene. oxide and butylene oxide. The preparation of polymers from these compounds is described in Ellis, The Chemistry of Synthetic Resins (1935 pages 990 to 994. These compounds are also referred to as polyalkylene glycols and their use as sensitizers for silver halide emulsions is described in U.S. Patents 2,423,549 and 2,441,389. The alkylene oxide derivatives may beprepared by condensing an organic compound containing an active hydrogen atom with an alkylene oxide polymer, or by condensing the active hydrogen compound with the alkylene oxide during. the polymer-ization of the latter material.

Variousderivativesof alkylene oxides may also be used, to sensitize the emulsions, e.g.,condensation productsof alkylene oxide with organic compounds containing, an active hydrogen atom. Examples of active hydrogen organic compounds, i.e., compounds in which a hydrogenatom may be replaced by reaction of the compound with metallic sodium, methylmagnesium iodide, etc., include alcohols, amines, mercaptans, acids, amides, hydrocarbons such as acetylene, and compounds having the active hydrogen in a methylene group such as dibenzoylmethane. More specifically, we may employ condensation products of alkylene oxide with glycols such as those having from 8'- to 18 carbon atoms asdescribed in U.S. Patent 2,240,472 and British Patent 443,559 as well as condensation products of alkyl'ene oxideswith aliphatic alcohols, condensation products of alkylene oxides with aliphatic acids, e.g., lauric acid and glycine, condensation products of alkylene oxides with aliphatic amines or amides, e.g., glycine and lauryl amide, and condensation products of alkylene oxides with phenols, e.g., phenol. The preparation of these condensation products is described in U.S. Patentl,970,578. Condensation products of alkylene oxides with hexitol ring dehydration products asdescribed in U.S. Patent 2,400,532 may also be employed.

In each case the polyalkylene oxide or derivative of alkylene" oxide should have a molecular weight of at least 300'. Condensation products of ethylene oxide' with long chain alcohols, acids, amines or amides should have a molecular weight of about 700; In general, the best results are obtained with the condensation products of ethylene oxide with long'chain compounds having achain length of 12 or more carbon atoms and with ethylene oxide polymers having a molecular weight of 1500 to 4000 or more.

When employing optically sensitized emulsions the optical sensitizing dyes are advantageously employed in about their optimum concentration which ordinarily lies between about 10 mgs. and 40 mgs. of optical sensitizing dye per liter of emulsion containing about 025 gram mole of silver halide although concentrations above or below the optimum concentration can be employed.

The alkylene oxide derivatives used to sensitize the emulsions may be illustrated by the following specific examples, although our invent-ion is in no way limited to the use of these. specific compounds HOCH CH O (CH CH O ,,CH CH OH Polyethylene oxide O(CH CH O),,OH CH OH owmomoncnzornorr Di- (polyethylene-glycoxy -decane HO CH CH O (CH CH O),,CH CH OC H' Polyethylene oxide oleyl ether HO CH CH O (CH CH' O )',,CH CH 0-CO-C H Polyethylene oxide oleic ester where n'=an integer greater than about 10.

Polyethylene oxide nonyl phenol ether N methyP myri'stylamino polyethylene oxide N-rnethyL-n -dodecylaniino' polyethylene oxide optimum reaction temperature is 100 to 105 C. The

product so obtained: is. a. light amber colored waxy material; thecolor may be removed partially by treatment with charcoal in a suitable solvent.

This material is repres'ent'a'tive of anumber of condensation productsof ethylene oxide with secondary with gelatino-silver bromoiodide emulsions.

graphic Process, 1942, page 3).

amines the alkyl' chain of which should contain at least nine carbon atoms and the polyethylene oxide chain should have a molecular weight of at least 500.

The preparation of silver halide emulsions involves;

" three separate'operations: (1'), the emulsification' and digestion: o1". ripening of the: silver halide, ('2) the freeing of the emulsion: from aqueous soluble salts usually by washing, (3') the second digestion or after-ripening to obtain increased sensitivity (Mees, The Theory of the Photo The sensitizing agents may be addedat any stage, preferably after the final digestion..

The photographic emulsions which we use are of the developing-out typeand best results have been obtained- However, emulsions ofvaryinghalide content may be used.

The emulsions maybe chemically sensitized by any of the accepted procedures, in addition to or in combination with the sensitizingv with alkylene. oxide polymers. The emulsions may be digested with naturally active gelatin, or sulfur compounds may be added such as those described in Sheppard, U.S. Patents 1,574,944 and 1,623,499, and Sheppard. and Brigham, U.S. Patent 2,410,689.

The emulsions may also be treated with salts of the 9 noble metals such as ruthenium, rhodium, palladium,

iridium and platinum, all of which belong, to group VIII of: the periodic table of. elements and have an atomic weight. greater than 1.00.. Representative compounds are ammoniumc'hloropalladate, p'otassiumchloroplatinate and sodium chloropalladite, which are used forsensitizing in amounts below that which produces any substantial fog inhibition, as described: in Smith an'd TriVelli, U.S. Patent. 2,4'48,0'60 and as: anti-foggants in higher amounts, as described in Trivelli and Smith, U.S. Patents 2,566,245 and 2,566,263.

The emulsions may also be chemically sensitized with gold salts as described in Waller and Dod'd, U.S. Patent 2,399,083, or stabilizedwith goldsalts as described in Damschroder', U.S. Patent 2,597,856, and Yutzy and Leer-- makers, UZS. Patent 2,597,915. Suitable compounds are potassium chloroaurite, potassium aurithiocyanate, potassiur-n chloroaurate, auric trichloride and 2-aurosulfobenzothiazol'e methochloride.

The emulsions may also be chemically sensitized with reducing. agents such as stannous salts (Carroll, U.SL Patent 2,487,850), polyamines such as diethylene triamine (Lowe and Jones, U.S. Patent 2,518,698), polyamines such as spermine (Lowe and Allen, U.S. Patent 2,521,- 925 or bis-(fl-aminoethyl) sulfide and its watersoluble salts (Lowe and Jones, U.S. Patent 2,521,926).

The emulsions may alsobe stabilized with the mercury compounds of Allen, Byers and Murray, U.S. application Serial No. 319,611; Carroll and Murray, U.S. application Serial. No. 319,612; and Leubner and Murray, U.S. application Serial No. 319,613, all filed November 8, 1952, now U.S. Patents 2,728,663, 2,728,664 and 2,728,665 respectively, granted December 27, 1955.

Other stabilizing agents may be added to the emulsions containingthequaternary ammonium. compounds and polyalkylene oxides such as cadmium chloride, cadmium.

nitrate, cobalt nitrate, manganese chloride, manganese sulfate, zinc chloride, zinc nit-rate and zinc sulfate. 4

When using the combination of the quaternary ammonium compound and the ethylene oxide polymer for sensitizing photographic emulsions the fog was found 5 to be increased somewhat on both fresh and incubated samples of the developed emulsion. This fog was reduced to normal levels by use of an antifoggant such as an azaindene, for example, a 4-hydroxy-6-alkyl-1,3,3a,7- tetraazaindene specifically 4-hydroxy-6-methyl-l,3,3a,7- tetraazaindene and 5-carboxy 4 hydroxy-1,3,3a,7-tetraazaindene.

These and other azaindene compounds useful for this purpose are disclosed in U.S. Patent 2,716,062; and Allen' et al., U.S. application Serial No. 365,541, filed July 1, 1953, now U.S. Patent 2,735,769, granted February 21, 1956; Allen et al., U.S. application Serial No. 426,547, filed April 29, 1954, now U.S. Patent 2,743,181, granted April 24, 1956; Tinker et al., US. application Serial No. 515,785, filed June 15, 1955, now U.S. Patent 2,835,581, granted May 20, 1958; Reynolds, U.S. application Serial No. 520,120, filed July 5, 1955, now U.S. Patent 2,756,- 147, granted July 24, 1956; Carroll et al., U.S. application Serial No. 426,543, filed April 29, 1954, now U.S.

Patent 2,743,180, granted April 24, 1956; Zeitschrift fiir 78 Wiss. Phot. 47, 2-28 (1952). v

However, the speed increases are nevertheless obtained using the quaternary compounds in the absence of such antifoggants as attested by the examples hereinafter.

The following examples illustrate my invention.

In the examples the polyalkylene oxides and derivatives thereof are identified as follows, the number following each name indicating the molecular weight of the particular polyethylene oxide chain.

Compound No.: I I PEO XV-Oleyl ether polyethylene oxide 1800 PEO XVIOleic ester polyethylene oxide 1000 PEO XVII-Oleic ester polyethylene oxide 6000 PEO XVIIINony1phenol ether polyethylene oxide 1145 PEO XIX-N-methylniyristylamino polyethylene oxide 1045 PEO XXOley1 ether polyethylene oxide 1500 PEO XXIN-methyl-n-dodecylamino polyethylene oxide 1145 PEO )QGI-Polyethylene oxide. 1540 PEO XXIII-Polyethylene oxide 4000 Developer DK-:

, 6 iodide emulsion which had been digested with a sulfur compound such as disclosed in Sheppard U.S. Patent 1,574,944 and potassium chloroaurate were added the compoundsshown in thefollowing table. The emulsions were coated on a cellulose.acetatesupport in the conventional manner. Thecoatings were exposed on an East: man type Ib sensito'meter and processed for 5 minutes in Kodak Developer DK-5O having-the following composition with the results shown in the following table, speed being read as 30/E where E'is the'exposure in meter candle seconds required'to produce a density of 0.2 overfog:

Grams N-methyl-p-aminophenol sulfate 2.5 Hydroquinone 2.5 Sodium sulfite, desiccated 30.0 Sodium metaborate 10.0 Potassium bromide 0.5 Water to make 1 liter.

Grams Sample Compound per mole 30/E- Gamma Fog A 0 5,700 .91 .03 I 7,050 .87 .04 g g 9, 900 -97 .04 12,200 .90 .00 .510 13,400 1.07 .10 Quat.I 2.5

This, example readily shows the supersensitizing elfect of the combination of the polyethylene oxide with the quaternary ammonium compound. Sample .801 containing the oxide has a speed of only 9900, and sample 792 containingthe pyridinium compound has a speed of only 12,200, whereas the combination of the two in the emulsion as in sample 804 yields a speed of 13,400.

Example 2.Addition ;of. the polyethylene oxide. and

tetraazaindene to the emulsion and the quaternary ammonium salt to the developer Coatings were prepared as described in Example .1, except the emulsion contained the following addenda and 'Was processed in the following developers for the indicated times:

Grams- 5 DK-50 5 DK50+0.5 g./l. I per Quat. XIII Sample Compound mole AgX v 30/E Gamma Fog 301E Gamma Fog 0 3, 950 1.11 v .30 e400 1,18 .32 1. 0 5,700 1. 09 .30 9900 1. 10 .33 0.65 7, 050 1.13 .30 9250 1.17 .32 f3 s, 050 1.01 .32 11, 900 1.19 .32

The particular tetraazaindene used in the examples, 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene, is identified as Aza.

Example 1.Addition of the polyethylene oxide, quaternary ammonium salt and azaindene, to the emulsion before coating To samples of a panchromatic gelatin-silver bromo- Example 3.Addition of quaternary ammonium salt and 'tetraazaindene to' the emulsion and the polyethylene oxide to the developer 1 Emulsion is similarto that described in- Example, 1, containing the following addenda and exposed and processed as indicated: a

Example 4.Addition of the polyethylene oxide, quater-. nary ammonium salt and stabilizing agents to the emulsion before coating The coatings were prepared as described in Example 1', except that the emulsion contained the addenda described in the following table.. The coatings were exposed on a Ib sensitometer and processed in the devel-. oper given for the times indicated. For convenience the speeds indicated in the table are measured as 100 (Ilog 11 E), where isthe exposure in meter candle seconds required to produce a density of 0.3 above fog.

1 Gms. Compound Sample "Compound Mole in Pre- Gms./l. /E Fog in Emulsion AgX exposure. I 1

. bath.

Bis(ethoxy diethyleneglycol)succinate-Gray U.S.. patentv application, Serial No.

532,756, filed September 6, 1955.

Example 5.Addition of one or all of the polyethylene 35 oxide, the quaternary ammonium salt, and the azaindene, either to the emulsion or to the developer The. coatings were prepared as described in Example 1, except that the emulsion contained the addenda described in the following table. The. coatings were ex- 40 posed on a Ib sensitorneter and processed in the developer's" given, for the indicated times.

Example 7.Additi0n of both the polyethylene oxide and the quaternary ammonium salt to the emulsion before coating To an emulsion similar to that described in Example lythe following were added. The coatings were exposed and processed as in Example 1.

' 5' DK- 2 5' DK50=+ r 5' DK-50.+ 2 Grams 5' D1950 g./l. PEO XV g./1.Quat.l .g./1. PEO XV+ Sample Compound per 1 g./l. Quat; I

. mole AgX J 301E Fog 30/E Fog 30/E Fog ISO/E" Fog 7,700' .25 10,900 .28 15,800 .42 19,000 .43 1.7 8,850 .25 12,200 .29 10,900 .47 22,000 .48 {g 15,000 .31 15,000 as 19,500 .55 21,500 .53 15,000 .37 10,500 .09 10,500 .53 22, 500 .50

' The data can. be quickly assessed by noting that the speed values (of samples 907, 908 and 909) 7700, 10,900, 8850, 12,200 and 15,000 represent development with the Gram quaternary compound present in neither emulsion nor Sample Compound iggi 30/ amma F g developer. Agx The example clearlyil'lustrates that the quaternary ammonium compounds are highly efiective when present 1.7 7, 550 1. 25 .20 in the developer alone or together with thepolyethylene 11,400 1.10 14 oxides, for the development of emulsions tree ofl, or 9 900 27 containing either or both of these sensitizing agents. Example 6.-Additi0n of one of the polyethylene oxide, 15,000 1.11 .37

the quaternary ammonium salt, or the' azaindene' either directly to the liquid emulsion, or by means of a preexpo'sure bath of the coated film The coatings were prepared as described in Example Kodak Developer DK-50. 75

Example 8.Addition of different polyethylene oxides and quaternary ammonium salts to the emulsion before coating To an emulsion similar to that described in Example 1, the following were added. The coatings were exposed and processed as in Example 1.

The emulsions of Example 12 can, of course, contain the indicated quaternary ammonium compounds to further increase the light-sensitivity or additionally the other. sensitizing agents referred to above prior to the examples. High contrast emulsions conventionally used in the graphic arts for half-tone work and sensitized asvin Example 12 with compound XIX exhibit unusually good image quality.

The chemical sensitizing agents and other addenda which we have described may be used. in various kinds of photographic emulsions. In addition to being useful in non-optically sensitized emulsions they may also be used in orthochromatic, panchromatic and X-ray emulsions. They may be added to the emulsion before or after any sensitizing dyes which are used. Various silver salts may be used as the sensitive salt such as silver bromide, silver iodide, silver chlorideor mixed silver halides such as silver chlorobromide or'silver bromoiodide. The agents may be used in emulsions intended for color photography, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers. 7

The dispersing agent for the silver halide may be gelatin or other colloidal material such as collodion, albumin, cellulose derivatives or synthetic resins.

It will be understood that I contemplate as included within our invention all modifications and equivalents falling within. the'scope. of the appended claims.

What I claim is:

1. Av light-sensitive silver halide emulsion sensitized with a mixture of an alkylene oxide polymer selected from the class consisting of (1) polyalkylene glycols and (2) condensation products of alkylene oxide with organic compounds containing an active hydrogen atom, said alkylene oxide containing from 2 to 4 carbon atoms and said alkylene oxide polymer having a molecular weight of at least 300, and a bis-quaternary ammonium salt silver halide chemical sensitizing agent the quaternary ammonium groups of which are linked together by a chain of at least seven atoms.

2. The emulsion of claim 1 containing as a fog inhibiting agent 4-hydroxy-6-alkyl-1,3,3a,7-tetraazaindene 3. The emulsion of claim 1 in which the alkylene oxide polymer is an ethylene oxide polymer.

'4. The emulsion of claim 1 in which the alkylene oxide polymer is a polyethylene oxide oleyl ether.

5. The emulsion of claim 1 in which the quaternary ammonium salt is a tetraalkyl quaternary ammoniumsalt.

6. The emulsion of claim 1 in which the quaternary ammonium salt is one in which a quaternary nitrogen atom is a part of a ring system.

7. The emulsion of claim 1 ll'LWhiCh the quaternary ammonium salt is decamethylene a-w-bis(oxymethyl pyridinium)-perchlorate.

8. A light-sensitive silver halide emulsion containing as sensitizing agents polyethylene oxide oleyl ether and decamethylene-a-w-bis(oxymethyl pyridinium) perchlorate.

9. The emulsion, of claim 8 containing as a fog inhibiting agent 4-hydroxy-6-methyl-l,3,3a,7-tetraazaindene.

10. The method of increasing the sensitivity of a silver. halide emulsion, which comprises exposing said emulsion and developing it in the presenceof an alkylene oxide polymer selected from the class consisting of (1) polyalkylene glycols and (2) condensation products of alkylene oxide with organic compounds containing an active hydrogen atom, said alkylene oxide. containing from 2 to 4 carbon atoms and said alkylene oxide polymer having a molecular weight of at. least 300, anda bis-quaternary ammoniumsalt silver halide sensitizing agent, the quaternary ammonium groups of which are linked together by achain of at least seven atoms. 1 r

11. The process of claim 10- in which at least one of said alkylene oxide polymer and ammonium salt is present in the emulsion prior to exposure.

12. The process of claim 10 in which the alkylene oxide polymer is an ethylene oxide polymer.

13. The process of claim 10 in whichv the quaternary ammonium salt is a tetraalkyl quaternary ammonium salt.

14. The process of claim 10 in which the quaternary ammonium salt is one in which a quaternary nitrogen atom is a part of a ring system.

15. The process of claim 11 in which the polyalkylene oxide is polyethylene oxide oleyl etherand the quaternary ammonium salt isdecamethylenea-w-bis(oxymethyl pyridinium) perchlorate.

16. The process of claim 10. in which the quaternary ammonium salt is present in the solution used to develop the: emulsion.

17. The process of claim 10 in which the quaternary ammonium salt is decamethylene-a-w-bis(oxymethyl pyridinium) perchlorate present in the solution used to develop theemulsion.

18. The process of claim 10 in which the quaternary ammonium salt is decamethylene-a-w-bi's(oxymethyl pyridinium) perchlorate present in the emulsion prior to exposure.

19. The emulsion of claim 1 containing a cadmium salt as an antifogging agent.

20. The emulsion of claim 1' in which the quaternary ammonium salt is tetradecamethylene-bis(pyridinium perchlorate) References Cited in the file of this patent UNITED STATES PATENTS 2,271,623 Carroll Feb. 3, 1942 2,410,690 Smith et al Nov; 5, 1946 2,716,062 Carroll et al. Aug. 23, 1955

Claims

10. THE METHOD OF INCREASING THE SENSITIVITY OF A SILVER HALIDE EMULSION, WHICH COMPRISES EXPOSING SAID EMULSION AND DEVELOPING IT IN THE PRESENCE OF AN ALKYLENE OXIDE POLYMER SELECTED FROM THE CLASS CONSISTING OF (1) POLYALKYLENE GLYCOLS AND (2) CONDENSATION PRODUCTS OF ALKYLENE OXIDE WITH ORGANIC COMPOUNDS CONTAINING AN ACTIVE HYDROGEN ATOM, SAID ALKYLENE OXIDE CONTAINING FROM 2 TO 4 CARBON ATOMS AND SAID ALKYLENE OXIDE POLYMER HAVING A MOLECULAR WEIGHT OF AT LEAST 300, AND A BIS-QUATERNARY AMMONIUM SALT SILVER HALIDE SENSITIZING AGENT, THE QUATERNARY AMMONIUM GROUPS OF WHICH ARE LINKED TOGETHER BY A CHAIN OF AT LEAST SEVEN ATOMS.