May 6, 1947. A. P. H. TRIVELLI ETAL 2,419,975 INCREASING SPEED AND CONTRAST OF PHOTOGRAPHIC EMULSIONS Filed Aug. 26, 1943 H| | | | | | | | | | || | | | | | | | | | IF | | | | | | | | | | III ADRIAN PH, TRIVELLI MVILLIAM. F. SMITH INVENTORS "6 Sé. Af Patented May 6, 1947 2,419,975 UNITED STATES PATENT OFFICE 2,419,975 INCREASING SPEED AND CONTRAST OF POTOGRAPHICEMULSIONS Adrian P. H. Triveli and William F. Smith, Company,Rochester, N.Y.,Roehester, assignors N. Y., to a Eastman corporation Kodak of -New Jersey Application August 26, 1943, Serial No. 500,088 16 Claims. (Cl. 95-6) 2 This invention relates to photographic emul material but are used only to fog all of the unex Sions and particularly to a method for increas posed silverhalide. ing the Speed and cohtlast of Stich emulsions. It is an object of the present invention to pro The invention relates to the use of hydrazine vide an improved method for sensitizing photo and related compounds in a photographic proceSS. graphic silver halide emulsions. A further object Hydrazine and hydrazine derivatives have been is to provide a new method for increasing the used in photographic emulsions or developers for speed of photographic silver halide emulsions. many purposes. One Well known use of hydrazine A still further object is to provide a new method compounds in photographic emulsions is that of for increasing the contrast of photographic silver a halogen acceptor or halogen absorber. During 0 halide emulsions. A further object is to provide the exposure of a sensitive silver halide emulsion, a new method for processing photographic silver the silverhalideis thought to release halogen such halide emulsions to effect improved properties as bromine or chlorine and the sensitivity of the in the resulting image. Other objects will appear material is improved if the halogen thus released from the following description of our invention. is immediately combined With a compound which 5 These objects are accomplished by developing prevents it from recombining with silver. The an undeveloped silver halide photographic emul use of hydrazines for this purpose is described in sion, after exposure, at a pH of about 9.5 or higher Caldwell U. S. Patent 956,567. This effect of in the presence of a hydrazine, hydrazine Salt, or absorbing or accepting halogen is manifested hydrazine derivative of the general formula: only during exposure of the sensitive material. 20 The hydrazine or other compound used in this way is intended to be used tip during the exposure of the Sensitive material and it is customary to remove the unused compound prior to develop where at least two R.'s are hydrogen atoms and ment. 25 the remainder are carbon radicals, more Spe Hydrazine derivatives have also been used as cifically an aliphatic radical, -a, heterocyclic anti-foggants in sensitive emulsions. This use is radical, or a carbohyl group directly connected described in Sheppard and Wightman U.S. Patent to an aliphatic carbon atom of a carbon radical, 1,763,990. When used for this purpose, the hy a heterocyclic carbon atom of a carbon radical, drazines prevent the formation of emulsion fog 30 an oxygen atom of a carbon radical or a nitro at the time of exposure of the Sensitive material gen atom of a carbon radical. or shortly before or thereafter. They have no The drawing illustrates typical sensitometric function in the development of the exposed mate curves showing the improvement obtained by our rial. invention. Hydrazines have also been used in photographic 35 We secure an improvement in the sensitivity emulsions to increase the infra-red speed and characteristics, that is, the speed or contrast, or contrast of the material as described in Trivelli both, of photographic material by developing the and Carroll U. S. Patent 2,245,236. When used exposed material in the presence of a hydrazine in this way the hydrazines act in the infra-red or a compound related to hydrazine. It is in region of optically Sensitized material. It was not 40 portant that these compounds be present at the known that an increase in speed and contrast in time of photographic development since the effect the visible and ultra-violet regions of the spec which we obtain is a development effect. Our trum could be obtained by the use of these mate compounds may, accordingly, be added to the rials. emulsion or to the developer as long as they are Hydrazines have also been used in photographic 45 present during development of the exposed mate developers for two purposes. They have been rial. Prior users of hydrazines in the photo graphic emulsion have sought to obtain benefits used as the developing agent, and have also been from their use, during exposure of the material used in fogging second developers to render re and not during development. The only excep Versal exposure of the material unnecessary. 50 tion is the Trivelli and Carroll U. S. Patent When used in this way they do not affect the speed 2,245,236, referred to above, and in this case the or contrast of the material. Since the effective effect is limited to the red alad infra-red region speed and contrast are deterrained by the original of the spectrum. When the hydrazines employed development, the hydrazines in the second de in the prior art have been incorporated in the veloper do not affect these characteristics of the 55 developing Solution, they have been used either 2,419,975 3 as the developing agent or as the fogging agent 12. in a reversal developer and would not effect an improvement in sensitometric properties of the No-C-NHNHHC) photographic material. p-Nitrophenylhydrazine hydrochloride The following classes of compounds have been 5 13, found suitable for use according to our invention: ey -sul ISO Hydrazines of the general formula: K CY - O a-Methyl-a-pheny hydrazine sulfate in which R, is hydrogen, an acid ester group or a Hydrazides (acyl hydrazines) having the gen heterocyclic group. The following compounds eral formula: illustrate this class. 1. NHNH2.2EIC) Hydrazine hydrochloride 5 2. NENHO where R is an alkyl radical or a chemical bond to Hydrazine hydrate a similar radical and R' is an aryl radical. 3. NH2NEICO OCEI. Ethylhydrazine carbonate 20 14 l, 4. A/ C-NHN c? Yohic ONEN OO a-Acethydrazide pyridinium chloride YN 25 2-benzothiazolylhydrazine 5. n 30 c? CICONNIC O-K X 2-quinolyhydrazine 6-Benzoylacethydrazidopyridinium chloride 6. NHNH C 35 16, ?--se ONEINH O). l N 2d–{ X 4-hydrazinoquinaldine CE The product made, by adding ethyl chloro 7. 40 acetate to 2-phenyl pyrimidazole, followed by treatment with hydrazine. The structure is preSunably as given ? NEINE 17. CoNHNH, Na - * 2-pyridylhydrazine 45 { >NC N CONNE Alkyl or aryl hydrazines of the general formula: Yir R Malonyl dihydrazide pyridinium bromide 8. NE-NE-R O NH-NY N 50 R where R and R are alkyl or aryl groupS. n The following compounds illustrate this group: of YoHoN ONENE-X X 8. 55 B-Phenylacethydrazidopyridinium chloride Ho-(D-NHNH, HCI 19. CH p-Hydroxyphenylhydrazine HCl { X-CH-)-CH,C ONNE Cl 9. CH3 &H, Y-NH.H Cl 60 Benzyl-dimethyl-acethydrazido-ammonium chloride Ch? 20. CONHNH as Dimethyl hydrazine hydrochloride of, 10. 65 Yo ONEINH No-K X-NHNL, Malonic acid dihydrazide NO 21. CONN 2,4-dinitrophenylhydrazine ONNE 11. 70 Oxalic acid dihydrazide N-NEHC 22. CH-CONHNH d-c ONEINE {X-ri, &B-c ONNE a-Benzyl-a-phenylhydrazine hydrochloride 75 Aconitic acid trihydrazide 2,419,975 6 Typical compounds are as follows: K O-H-conHNE, 84 . &H,- CONHN Phenylsuccinic dihydrazide 5 Semicarbazides, carbohydrazides and amino ah, biurets having the formula: of YoH,conENEconHN=c Chs RY--NHNH, 10 The acetone derivative of 26 R? 35 r 2 where R is hydrogen and R' is hydrogen, NH2 which may or may not be substituted, an aryl 15 CHs GHs t radical, or a carboxylic acid amide radical. c? YoHooNHN=5 (-NHN.coon? Yo 24. NHCONHNH2.HCl The diacetyl-derivative of #14 Semicarbazide-hydrochloride 36. ZN 25. NEINEICONEINEI.HCl 20 Carbohydrazidehydrochloride l c? YoHooNHN=CHCHOHOHOHCHOHCHOHCH-OH 26. The glucose derivative of #4 25 37. C3 CH SN M. N. Cl CHCONEINHCONHNH KD-CH-)-cisconHN=c(w bH, YoH. :Cl Acetcarbohydrazide pyridinium chloride 30 Acetone-derivative of #19 The increase in sensitivity or contrast which We obtain by the introduction of hydrazines to 27. ? the emulsion or developer, whether as water soluble or as Water-insoluble compounds increases X conHNHOONHNE, 35 considerably With increase in pH of the developer. Bir YC t The pH of the developer used with our materials CONHNHCONHNH should be about 9.5 or higher. With a developer having a pH of 12.8, the use of hydrazine in a Malonyl-dicarbohydrazido pyridinium bromide silver chlorobromide emulsion produces a strong 28. 40 effect by which the gamma can be increased from 3 to a gamma of iO or higher. With some emul NNEC oNH-O-C) Sions a gamma, as high as 24 has been obtained. 4-(p-chlorophenyl)-semicarbazide Speed increase Without gamma increase, Speed increase with gamma increase and gamma in 29. NaNHCONH- 45 crease without speed increase have been observed. In addition to pH, the pAg or silver ion con &H, centration, of the emulsions to which an active compound is added, is an important factor in 4-(o-tolyl)-semicarbazide controlling the effect which we obtain. Higher 30. 50 silver ion concentrations tend in general to in NENECONH- - Cl crease the effect as do high pH's. It is also important not to add carbonyl hardening agents s to the emulsion.