US3361565A - Silver halide photographic element containing a polyanionic color former and a gelatin antiabrasion layer - Google Patents

Description

United States Patent 3,361,565 SILVER HALIDE PHOTOGRAPHIC ELEMENT CON- TAINING A POLYANIONIC COLOR FORMER AND A GELATIN ANTIABRASION LAYER Jacob Quentin Umberger, Holmdel, N.J., assignor to E. I. du Pout de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Ian. 21, 1964, Ser. No. 339,112 11 Claims. (Cl. 96-74) ABSTRACT OF THE DISCLOSURE A multicolor photographic element having (1) differentially sensitized silver halide emulsion layers containing color formers one of which is a polyanionic color former, the layers having an integral thickness, 6, of not more than 12.5 microns and (2) a gelatin antiabrasion layer containing an organic plasticizer having an O atom doubly bonded to C, P or S and free from H atoms more acidic than pK =19, a boiling point above 200 C., a melting point below 40 C. and soluble in water to at least 0.5 g. per liter.

This invention relates to color photography and more particularly to multicolor elements for chromogenic development.

Multilayer color films containing polymeric colorformers have been proposed and these have been found to yield the thinnest emulsion layers of any integral coupler system. Such multilayer color films are disclosed in assignees copending application of Chu et al., Ser. No. 113,100, filed May 29, 1961, now US. Patent 3,211,552. Such films, however, have suffered from brittleness of the color-forming layers in dry atmospheres or climates. In addition to the ionizable groups, another contributor to this brittleness is the amide linkage, CONH, by which the coupler group is attached, directly or indirectly, to the polymer backbone. Normally, atmospheric moisture or water molecules are believed adsorbed to such polar sites but, in dry atmospheres, loss of adsorbed water frees these sites to set up a 3-dimensional network of intermolecular hydrogen bonds which prevents the free rotation around chemical bonds necessary for plastic flexing and bending.

An object of this invention is to provide improved multilayer elements for chromogenic development. Another object is to provide multilayer color films for chromogenic development which have both high resolving power values and the processing simplicity of integral coupler emulsions. A more specific object is to provide such films having improved flexibility, especially at low relative humidities. Yet another object is to provide a simpler means of adding plasticizing materials without causing coating and sensitometric defects and without requiring the use of special equipment. Still further objects will be apparent from the following:

The improved multicolor elements of this invention comprise a support bearing 1) a plurality [preferably three] of differentially sensitized silver halide emulsion layers, each adapted to record images from light in a different region (e.g., primary color region) of the visible 3,361,565 Patented Jan. 2, was

spectrum and containing a color former having at least one nucleus capable of forming a dye selected from the group consisting of quinoneirnine, azomethine and azo dyes upon color coupling development of the exposed element, and gelatin or a mixture of gelatin and another polymeric binding agent (e.g., a vinyl addition polymer) for the silver halide crystals, and coated over said plurality of emulsion layers (2) a gelatin antiabrasion layer containing an organic plasticizer having an oxygen atom in the molecule which is doubly bonded to carbon, phosphorus or sulfur, and being free from hydrogen atoms more acidic than pK,,-=l9 and having (a) a boiling point above 200 C., (b) a melting point below 40 C., and (c) a solubility in water of at least 0.5 and preferably more than 3.0 g. per liter at 25 C. The binding agent and color former can be the same, i.e., a polymeric color former, preferably polyionic. The support preferably does not absorb the plasticizer. Preferred supports embody meltcast, oriented polyester, e.g., polyethylene terephthalate and polycarbonate films.

Preferably, the gelatin antiabrasion layer will also comprise a colloidal dispersion of a low-melting, noniouized, water-insoluble, synthetic, vinyl addition polymer, preferably an acrylic acid or methacrylic acid methyl or ethyl ester, in the form of a soft gel-like solid at room temperature. Other auxiliary layers (i.e., antihalation, separator and filter layers) may also contain a plasticizer and/or a colloid dispersion of vinyl addition polymer as defined above. The polymer, which may be in the plasticized state, should have a second order transition temperature (glass transition temperature) of 0 C. or below.

In exemplification of the invention, a hydrophobic film support, e.g. cellulose acetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetatebutyrate, etc., or a superpolymer such as nylon, polyvinyl chloride, polyester, e.g., polyethylene terephthalate, polycarbonate, etc., glass, wood, paper, etc., suitably subbed to provide proper adhesion with layers to be coated thereon, is coated on one surface with an antihalation layer comprising gelatin in which there is dispersed colloidal silver capable of absorbing light of all visible wave lengths. Coated in order on the antihalation layer are a gelatino-silver halide emulsion layer sensitive to blue and red light and containing a polyanionic cyan color-former, a gelatin separator layer, a gelatino-silver halide emulsion layer sensitive to blue and green light and containing a polyanionic magenta color-former, a gelatin layer containing a blue light-absorbing material, e.g yellow colloidal silver, a gelatino-silver halide emulsion layer sensitive to blue light and containing a polyanionic yellow color-former. Finally, there is coated an antiabrasion layer from an aqueous coating solution comprising gelatin, a plasticizer as described above, e.g. triethyl phosphate, a colloidal dispersion of a vinyl polymer (polyethyl acrylate), a gelatin hardening agent such as chrome alum and a non-ionic surfactant. The antiabrasion coating solution contain 2% by weight gelatin, 3% by weight plasticizer and 2% by weight vinyl polymer.

In the above-mentioned Chu et al. application, there are discolored color-formers, emulsion formulations, coated elements and processing procedures suitable for use in this invention with the exception that the simple gelatin antiabrasion layer of that reference is to be replaced with an antiabrasion layer comprising the high boiling plasticizer and, optionally, the dispersion of a vinyl polymer as described above. A dispersion of a vinyl polymer may also be added to the silver halide layers and/or one or more of the non-photosensitive layers e.g., the antihalation layer as disclosed in assignees copending application, Firestine and Stevenson, U.S. Ser. No. 183,759, filed Mar. 30, 1962, abandoned Jan. 17, 1965.

The light-sensitive emulsion layers may be arranged with respect to the support in other manners and with other arrangements of spectral sensitivities and colorformers as is known in the art. Suitable other layer arrangements are disclosed in US. Patents 2,397,864, 2,927,019, 2,927,024, and U5. 2,997,338. However, the advantages of the thin emulsion layers of this invention will be most appreciated in a configuration in which the uppermost light-sensitive layer contains a yellow colorformer.

Suitable plasticizers are disclosed in an article by Alan S. Haisser in Modern Plastics Encyclopedia, 1963 Issue, vol. 40, No. 1A (September 1962), pages 456-457, fol- .lowed (pages 460-478) by a Plasticizers Chart. Any

of the plasticizers listed in this chart and conforming to the above characteristicsthigh boiling point, water-soluble, containing a doubly-bonded oxygen, etc.) are suitable. for inclusion in the compositions and elements of this invention. Other suitable plasticizers having the prescribed characteristics are disclosed in the book Plasticizers by D. N. Buttrey, 2nd edition, 1957, Cleaver- Hume Press, Ltd., London. Since the'antiabrasion over- .coating should contain a sufiicient quantity of a watersoluble plasticizer to diffuse throughout all layers of the film element, the plasticizer should have at least the minimum solubility specified. Thus many common plasticizers which have a solubility of less than 0.5 g./liter would be unsatisfactory in this invention, e.g. tricresyl phosphate, dimethyl sebacate, dioctyl phthalate, triethylene glycol di-2-ethylhexoate and ethyl phthalyl ethyl glycolate.

Other compounds, normally referred to as plasticizers, e.g. glycerine, diethylene glycol and triethylene glycol, should more properly be considered as humectants. These compounds do not themselves act strongly as plasticizers but they absorb water from the air and it is this absorbed water which acts as a plasticizer.,0bviously, such compounds are ineffective in fiexibilizing films if there is little or no water in the air, i.e. under conditions of low relative humidity. Furthermore, it has been found that these humectants cause problems such as poor emulsion aging stability under storage at high relative humidity. These compounds do not contain the required doublybonded oxygen atom of the present invention.

The preferred vinyl polymer to be added as a dispersion to the photographic emulsions is polyethyl acrylate. Its preparation using disodium-N-tallow-B-iminodipropionate as a dispersing agent, is described in Procedure A of assignees copending application, Nottorf, Ser. No. 94,989, filed Mar. 13, 1961 (US. Patent 3,142,568, July 28, 1964). In that same application there are disclosed a number of other suitable vinyl polymers, dispersed with various amphoteric dispersing agents. Although a wide variety of polymeric vinyl compounds are useful, the preferred compound is an acrylic acid methyl or ethyl ester taken from the group consisting of a homopolymer of an acrylic acid ester, a homopolymer of an a-hydrocarbon substituted acrylic acid ester and a copolymer of said acrylic acid esters, said copolymer containing at least 90% by weight of units of said acrylic acid esters. In general, the ionic dispersing agents are preferred for use in preparing the polymeric dispersions since they tend to form more stable dispersions than the nonionic agents. These preferred ionic dispersing agents in addition to the above-disclosed amphoteric agents, also include anionic dispersing agents such as disclosed 4 a as being useful in preparing vinyl polymer dispersions in assignees Nottorf application, Ser. No. 134,109, filed Aug. 28, 1961, now US. Patent 3,325,286, i.e. an ionic dispersing agent represented by the formula:

carbon atoms, e.g. 8 to 18 carbon atoms, and an organic radical of the formula IU-O-(O 01120132 wherein R is a branched chain alkyl radical of at least 4 carbon atoms, e.g. 4 to 12 carbon atoms, and n is a number of 1 to 12 and B is a radical selected from the group consisting of O -SO M and -O CO M where M is a cation selected from the group consisting of ammonium and an alkali or alkaline earth metal, e.g., lithium, sodium, potassium, rubidium and cesium, and m is 0 or 1.

Cationic dispersing agents are useful but less preferred because they may have a tendency to react with anionic color-formers. Also useful, but less preferred, are the nonionic dispersing agents since they may form somewhat less stable dispersions. Mixtures of any of the above-discussed dispersing agents may be particularly useful under certain circumstances. Whatever dispersing agent is employed, it

is desirable that the dispersion be prepared in such a mannet that the average particle Size does not exceed one micron, e.g., according to the procedures described in either of the above Nottorf applications.

In the above Chu et al. application, there is considerable emphasis on the importance of thinness of the emul- V sion layers in order to achieve superior results in terms of resolution, definition, etc. As disclosed in that application, it is desired that the integral emulsion thickness (6) not exceed 12.5 microns, preferably 7.6 to 12.5 microns, and that the effective color-forming equivalent weigh of the binder not exceed 1750, preferably 500-1750. The thickness value, 6, was originally defined in an article by I. Eggert and W. Grossman, The Resolving Power of Three- Layer Color-Films, Naturwissenchaften 39, No. 6, 132- 133 (1952), as the distance from the surface of the outermost photosensitive layer to one-third into the innermost photosensitive layer. The effective color-forming equivalent weight is defined in detail in the above Chu et al. ap-' plication but, briefly, is a measure of the efficiency of the total binder-color-former system in yielding thin color emulsion layers, defined as the quotient obtained when color-former equivalent weight is divided by the fraction of the total binder comprised of color-former. In the present invention, it is desirable to maintain the above ranges of thickness (6) and effective equivalent weight, even with the addition of plasticizers and vinyl polymer dispersions. It is significant to note that the addition of latex plus plasticizer to the abrasion and/ or non-halation layers does not increase the value of 5 appreciably.

The novel elements of this invention are particularly applicable to negative and reversal color films Whichare designed for exposure in a camera. In the case of color reversal films, the blue-sensitive layer should be outermost, and the remaining silver halide layers adapted to record in the red and green regions of the spectrum being disposed in any order and preferablyall on the same side of the support. The color-formers in the blue, green and red regions of the spectrum, in general, should yield dyes upon development complementary incolor to the utilized sensitivity of the respective silver halide emulsion layers.

The invention will be further illustrated, but is: not ill? tended to be limited to the following examples.

Example I Polyethylene terephthalate film 0.0045 inch in thickness having a vinylidene chloride copolymer l'ay'er'on one sur- 7 5 face, as described in Example IV of U.S. 2,779,684, was provided with a thin gelatin layer serving as a second substratum. This film base was then coated with aqueous dispersions as described in Table A in the order shown to form a color reversal film with the yellow emulsion outermost.

This G-layered film was now over-coated in separate sections with various antiabrasion layers comprising wator/ethanol (90/ 10 by volume) solutions of gelatin in 2% by weight concentration and the following plasticizers in 3% by volume concentration: (a) triethyl phosphate, (b) triethyl citrate, (c) glyceryl triacetate, (d) bis-(methoxyethyl) adipate. A control coating was also made without of the flexibilizing materials added to the experimental films produced any photographically deleterious effects.

Example II A six-layered color film was prepared which was identical with Example I except the support was cellulose triacetate of 0.0052 inch thickness having a thin gelatin anchoring substratum. Over separate sections of this film were coated antiabrasion layers similar to Example I in gelatin, hardener, and surfactant content and containing 3 parts of various high-boiling organic liquids per 2 parts of gelatin by weight. The films were tested at room tem- TABLE A Color Colloidal Gelatin PEA 1 Former Silver mgJdm. mg./dm. mgJdm. mgJdm.

Antihalation layer 11. 1 3. 7 3. 4 Cyan layer 2 11. 10. 5 7 6 Separator layer. 18. 0 1. 5 Magenta layer 12.9 5 7 6 0 Yellow filter layer 10. 0 l. 5 Yellow layer 4 5. 7 6 2 17. 3

1 Polyethyl acrylate (dry weight) obtained from the aqueous dispersion described in Examp e 1 The cyan color-former is a 1:1 copolymer of Hi ydroxy-N-(beta-vinyl-oxyethyl) -2-naphthamide and maleic anhydride as described in Example I of assignees copending application of Umberger, Ser. N 0. 113,101, filed May 29, 1961, refiled as continuation-impart application Ser. No. 419,227, Dec. 17, 1964 (U.S.P. 3.299,013, Jan. 17, 1967).

a The magenta color-former is a 1/1.25/0.75 copolymer of 1-phenyl-3'methaorylamido-5- pyrazolonelacrylic acid/acrylamide as described in Example V of assignees copending application, Firestine and Umberger, Ser. N 0. 21,959, filed Apr. 13, 1960 (U.S.P. 3,163,625,

Dec. 29, 1964) 4 The yellow color-former is a polyaniou benzoylacetanilide prepared by transacetalization of 100 parts of low viscosity 99% hydrolyzed polyvinyl alcohol with 120 parts of a-benzoyl acetamidobenzaldehyde ethylene glycol acetal and 50 parts of o-suliobenzaldehyde in an ethanol-water reaction medium with p-toluenesulfonlc acid to pH 1.7 as acetalization catalyst to yield a color-former of 775 equivalent Weight.

plasticizer, i.e., from 2% gelatin solution only. Chrome alum and non-ionic surfactants, e.g., saponin, were also present in these coating compositions. The temperatures of the solutions were 95-100 F. at coating and the coating speed adjusted so as to obtain a coating wgt. of dry gelatin of about 10 to mg./dm.

After drying and seasoning under ordinary room conditions for several weeks the coatings were subjected to the wedge-brittleness test described by P. Z. Adelstein in Journal of Photographic Science and Engineering, vol. 1, No. 2, October 1957, pages 63-68, in a room held at 10% relative humidity (RH). Also measured was the curl expressed in diopters, viz., the reciprocal of the radius of curvature measured in meters.

TABLE B Coating Emulsion Crack Curl Diopters Identification Diameter, inches perature as in Example I and the following results were obtained:

TABLE C pl ti i Emulsion crack diameter 0% RH, inches Triethyl phosphate 0.29 Propylene carbonate 0.31 N,N-dimethylcaproamide 0.39 Bis (Z-methoxyethyl) adipate 0.33 Dimethyl phthalate 0.35 Triacetin 0.35 Control (gel only) 0.40

A few of the films of the above set were again tested at 10% relative humidity but at 225 F. temperature compared with the previous room temperature tests.

TABLE D Plasticizer: gl f igff 3352* F., inches Triethyl phosphate 0.52

Triacetin 0.53

Control (gel only) 0.64

Example III A six-layered color film like that of Example II was made. However, the alcohol content of the antiabrasion layer coating composition was increased in order to dissolve plasticizers of lower water solubility than in the previous examples. In preparing the antiabrasion coating compositions, 15 parts by volume of the plasticizers were dissolved in 150 parts by volume ethanol and added slowly with stirring to 200 parts by volume of 4.5% aqueous gelatin solution (at 125 F.) containing the usual hardener and surfactants. The coating temperature was F. and coating speed 10 ft./min. From the following table, recording film testing as in Example I, it will be seen that some very water soluble materials, e.g., triethyl phosphate, have been included withless water-soluble plasticizers.

TABLE E Emulsion Plasticizer Crack Diam- Curl star at Diopters at RH, inches 10% RH Triethyl phosphate 0. 22 10 Tributyl phosphate 1 0. 23 23 Triacetin 0. 40 23 Dirnethyl phthalate 0.33 13 Bis-(methoxyethyl) adipate 0.37 17 Trichloroethyl phosphate 0.33 10 Acetyl triethylcitrate. 0. 39 13 Triethyl citrate 0.35 13 Butyl levulinate- 0. 31 13 Dimethyl adipate 0. 34 18 Diethyl adipate 0. 38 13 Bis-(methoxyethyl) phthalate 0.35 13 Adiponitrile 0.33 17 0. 35 13 1 0.37 33 Control (gel only) 0. 41 33 Control (no antiabrasion layer) 0.43

1 Phase separation. Curl in diopters is defined as the reciprocal radius of curvature in meters.

Additional coatings of antiabrasion layer were made and tested in the same manner as for Table E as shown in the following table.

TABLE F Plasticizer:

Emulsion crack diameter at 10% RH, inches Triethyleneglycol diacetate 0.39 Triethyleneglycol dipropionate 0.33 N-acetylmorphol-ine 0.39 l-acetylpiperidine 0.40 N-methylformanilide 0.40 Diethylethoxyrnethylene malonate 0.30 Alkylated phosphate ester (Vircol 189) 0.31 Polyethylene glycol (600) dibenzoate 0.29 T etramethylene cyclic sulfone 0.37 Control (gel only) 0.42 40 Example IV Coatings similar to those of Example 111 were placed in an oven at 125 F. overnight and then retested as in Example I for emulsion flexibility.

' TABLE G Plasticizer. 3 32 35 g g e Control (no antiabrasion layer) 0.51 0.34

Tn'ethyl phosphate Tributyl phosphate 0.31 Triacetin 0.42 Dimethyl phthalate 0.38 Bis-(methoxyet-hyl) adipate z- 0.35 Trichloroethyl phosphate 0.38 Acetyl triethyl citrate 0.39 Triethyl critrate 0.40 Butyl levulinate 0.35 Dimethyl adipate 0.40 Diethyl adipate 0.38 Bis-(methoxyethyl) phthalate 0.38 Adiponitrile 0.39 Diethyl succinate 0.41 Dibutyl adipate (phase separation) 0.42 Triethylene glycol diacetate Q. 0.33 Triethylene glycol dipropionate 0.46 N-acetyl morpholine 0.35 l-acetyl piperidine 0.35 Diethyl ethylphosphonate 0.38 N-methylformanilide 0.40 Diethyl ethoxymethylene malonate 0.30 V-ircol l89-'allk=yl phosphate ester 0:31 Propylene carbonate 0.41 Polyethylene glycol (600) dibenzoate 0.24 Tetramethylene cyclic sulfone 0.46

Control (gelatin only) 0.47

8 Example V It was discovered that plasticizers such as tributyl phosphate could be conveniently incorporated into antiabrasion layers by normal stirring in the presence of dispersed polyethyl acrylate in an aqueous gelatin solution. This is considered an important discovery because of the greater permanence of some of the less water soluble materials. Very insoluble materials, e.g., trioctyl phosphate or dibutyl phthalate could not be completely incorporated into the dispersed vinyl polymer/gelatin sys= tern, however.

4 To 6000 ml. of a 5% by weight aqueous gelatin solution there were added:

270 ml. of a 3.3% by weight chrome alum solution, 3 g. of silicone lubricant,

915 g. of polyethyl acrylate dispersion containing 30% by weight polyethyl acrylate and about 2.77% by weight amphoteric dispersing agent, prepared by emulsion polymerization as described in Procedure A of assignees.

surfactants.

The pH was adjusted to pH 6.0-6.2 at F. Portions of 375 ml. each were measured 15 ml. of the plasticizers of plasticizer mixtures tabulated below, dissolved in 60 ml. ethyl alcohol. Water was then added to each portion to make a total of 600 ml. The solutions were then skim coated at 1-0 ft./min. at 95 F. as antiabrasion layers over sections of the sixlayer color film of Example 11. The flexibility of these films was superior to those wherein the antiabrasion coating contained plasticizer alone and less water-soluble plasticizers, e.g., tributyl phosphate, were uniformly distributed in the coating. 2

In the above table the abbreviations have the following meaning:

PEA-:polyethyl acrylate dispersion TEP=triethyl phosphate TBP=tributyl phosphate TA=triacetin DMP=dimethyl phthalate BMEA=bis-(methoxyethyl) adipate TCEP=trichlorethyl phosphate AT EC=acetyl triethyl citrate Numbers in parentheses following the abbreviations indicate relative parts by volume.

and to each were added 9 Example VI TABLE 3' Additions to Emulsion antiabrasion layer: crack dia. inch Control (without abrasion layer) 0.44 TEP+PEA 0.20 TBP-l-PEA 0.22 TA+PEA 0.29 DMP-l-PEA 0.27 BMEA-i-PEA 0.27 TC-EP-i-PET 0.24 ATEC-l-PEA 0.35 DEEMM-i-PEA 0.35 Vircol 189 phosphate ester-l-PEA 0.36 PEGDB-f-PEA 0.18 TEGDA-l-P-EA 0.24 DEEP+PEA 0.20 TEC+PEA 0.33

The above table contains abbreviations as explained in Example V in addition to the following new abbreviations:

DEEMM:diethylethoxymethylene malonate Vircol 189 phosphate ester=ethylene oxide addition product of alkyl hydrogen phosphates as described in U.S.P. 2,990,421 PEGDB=polyethyleneglycol dibenzoate prepared from polyethylene oxide having a molecular weight of 600 TEGDA=triethyleneglycol diacetate DEEP=diethyl ethyl phosphonate TEC=triethyl citrate Example VII Experiments similar to Example V were performed employing, as before, 15 ml. plasticizer but with 100 ml.

ethanol to aid solution of the plasticizers, some of which proved too insoluble as will be seen.

*Trioctyl phosphate (/2 +TBP /2 +PEA 0.38 Trioctyl phosphate /s +PEGDB /3 +TBP /s)+PEA 0.37

The preceding table contains abbreviations as explained in Examples V and VI. An asterisk is used where an oily surface was observed, indicating that one or more of the plasticizers were too insoluble to enter the polyethyl acrylate latex particles. Flexols 4G0, A26, and 3GH behaved similarly in producing coatings with oily surfaces due to insuflicient water solubility for use in the present invention.

Flexol 460 is polyethylene glycol di-(2-ethylhexoate) Flexol A26 is di-(Z-ethylhexyl) adipate Flexol 3GH is triethyleneglycol di-(Z-ethylbutyrate) Example VIII Emulsion additives such as dispersion of soft vinyl polymer and plasticizers can, in lengthy contact with a liquid photographic emulsion, produce undesired sensitometric effects and coating disturbances. Accordingly, two multilayer color films were made in which only polymeric compatible color couplers were present with the usual gelatin and silver halide in the emulsion layers. One film, A, was made as a three-layer structure, i.e., emulsions containing cyan, magenta, and yellow color-formers were coated in that order on polyethylene glycol terephthalate film base of 0.0045 inch thickness. The second film, B, was made similarly to A but in a laminated structure with nonphotographic flexibilizing layers comprising gelatin, dispersed polyethyl acrylate and plasticizer intercalated between the cyan and magenta emulsions, and between the magenta and yellow emulsions, and coated as an antiabrasion layer. Film A cracked at 0.67" while film B cracked at 0.45", an obvious increase in flexibility.

The flexibilizing interlayer composition was prepared by combining 4000 g. of a 5% aqueous gelatin solution with 180 ml. of a 3.3% chrome alum solution at F. To this was added 610 g. of a polyethylacrylate dispersion (as described in Example V) along with saponin and t-CaHrr-QWCHzCHg) 10-011 surfactants. The pH was adjusted with 3 N NaOH solution to 6.0 to 6.2 at 100 F. To this was added slowly with stirring a mixture of:

The flexibilizing interlayer was skim-coated at 100 F. and 10 ft./min. coating speed to give a gelatin coating weight of approximately 20 milligrams per square decimeter.

The following examples illustrate the use of color formers other than those of the polyanionic type and the use of a thick plasticizer/gelatin/polyethyl acrylate latex abrasion layer which was improved flexibility characteristics and the additional advantages given below.

Example IX A color film was prepared similarly to that described in Example H but with omission of the 6th layer, i.e., the outer blue-sensitive yellow-coupling emulsion layer. This film was then coated in four separate sections as follows:

Emulsion Ooatmg Antiabrasion Layer Crack Dia. at 10% RH a 30 rng./dm. gelatin, 60 rug/Gm. PEA latex, 0.33 inch.

0.9 rngjdm. chrome alum plus surfactants. b Same as (a) plus 12 mg./drn. of triaeetin. 0.25 inch. 0 Saufie 1gas (a) plus 12 mg./dm. of tributyl phos- 0.20 inch.

p a e. d Same as (a) plus 12 IngJdm. of dimethyl 0.24.

phthalate. e None 0.45.

Polyetbyl aerylate (dry weight) obtained from the aqueous dispersion described in Example V.

The above coatings were cut into 10" and aged in contact with each other for at F. Coating (a), when processed, showed a mottled surface which was interpreted as due to tackiness of the anti-abrasion coat. Coatings (b), (c) and (d) showed x 35 mm. strips about 50 hours Example II but employing containing plasticizer to 1 l very good gloss and freedom from mottle due, it is believed, to the surprising action of the plasticizers in preventing latex tackiness.

Coatings (a) through (e) were exposed through photographic step wedges both with and without a Wratten No. 29 red filter on the same 35 mm. x strip. The exposed strips were then processed according to the procedure of five minutes first development at 75 F. for coating (e) and five minutes first development at 80 F. for coatings (a), (b), (c) and (d). It was observed that the gel. latex layer contributed wet-toughness to the films as shown by the freedom of coatings (a) through (d) from haze and reticulation compared with coating (e). Also, it was observed that the interimage development eifect to remove cyan dye from red areas was increased by the gel. latex outer layer. This could be seen in normal use of a color reversal film as resulting in brighter and better reproduction of reds.

Example X To demonstrate the usefulness of gel-latex overcoats for all types of integral couplers, e.g., polymeric, soaplike or dispersed lipophilic couplers, a 4-layer film similar to the first four coated layers of the 6-layer film of Example H was prepared. Also, the polymeric cyan coupler of that film was replaced by a non-diffusing coupler of the formula:

. S OsNa- Over a section of this 4-layer film was coated a layer as follows:

After drying, this film was exposed and processed as in Example IX. It was observed that the original 4-layer film showed processing haze and edge-frilling of the emulsion when processed at 80 F. and that the over-coating prevented such defects and led to increased interimage developments or masking efiects.

Other suitable color formers which can be substituted in similar amount for the color former of Examples IX and X are described in U.S. patents listed below-and described therein and in U.S. Patents 2,179,238 and 2,186,849;

The advantages of the elements described in Examples IX and X are:

(a) The thick antiabrasion layer of gelatin plus polyethyl acrylate promotes desirable interimage development or masking effects,

(b) The antiabrasion layers also permit higher temperature processing without occurrence of haze, reticulation and edge-frilling, and

(c) The addition of a high-boiling carbonyl groupthe gelatin polyethyl acrylate antiabrasion layer prevents tackiness and lap-to-lap sticking of rolls of the resulting film elements.

The preferred photographic elements have a hydrophobic organic polymer film base that is dimensionally stable and is provided with a vinylidene chloride copolymer coating on each surface. Suitable polyester filrn bases are described in Alles et al. U.S. Patent 2,627,088.

In addition to preventing undesired sensitometric effects, the use of a combination of plasticizers and dispersed vinyl polymer in the interlayer removes thickness 12 from the emulsion layers and adds to the separator layers which may reduce interlayer color contamination and possibly increase desirable interlayer development masking effects.

Elements made up of integral coupler emulsions obviously become more susceptible to interlayer color contamination (particularly the contamination due to migration of oxidized developer during the color development step) as the separator layers become thinner. It has been found that this color contamination can be efiectively reduced by the addition of a competing coupler, e.g., a phenol that forms a soluble removable dye on coupling (such as citrazinic acid). In particular, it has been found that larger concentrations of sodium sulfite and citrazinic acid are especially effective in combination with the polymeric binder-color-formers in reducing interlayer color contamination caused by migration of oxidized developer and by migration of color-former molecules. The films in which the vinyl polymer dispersion is removed from the emulsion and placed instead in the separate layers tend to show reduced contamination due to increased thickness of the separator layers. This, of course, does not increase the over-all film thickness since the light-sensitive emulsion layers are made correspondingly thinner by the absence of these materials.

lthough this invention is particularly applicable to' negative and reversal color films which are designed for exposure in a camera, it is also useful in other color films, which may have other than the conventional layer arrangements. The thin layers made possible by this invention can be used advantageously in negative, positive or reversal color films which may be for cine or still use,

in transparencies, prints for viewing by reflected light, intermediate films, etc.

The invention, moreover, is not limited to the specific light-sensitive material described in the above detailed examples. Various other simple and mixed silver halides may be used as the light-sensitive materials in like manner. Mixtures of silver bromides, chlorides, and/or iodides can be made from mixtures of soluble salts of these halides in like manner. Other useful soluble halides include calcium bromide, potassium iodide, sodium and potassium chlorides and iodides, etc.

It is apparent from the foregoing that materials at the lower end of the solubility range of this invention such as tributyl phosphate can be stirred into aqueous dispersion of soft vinyl polymers to obtain uniform coatings without use of high-speed stirrers. However, it is found that addition of a part of the emulsion gelatin to the aqueous dispersion prior to addition of plasticizer (in alcohol solution) is preferred to minimize any aggregation. This easily prepared mixture of tributyl phosphate, aqueous polymer dispersion, and aqueous gelatin can be added to any aqueous photographic emulsion. Such easily prepared mixtures of plasticizers of water solubility from 0.5 to 10 g. per liter at room temperature, e.g., dimethyl phthalate, with soft polymer aqueous dispersion are particularly advantageous from the viewpoint of resistance to loss by evaporation or water leaching compared with some of'the more Water soluble materials of the prior art, e.g., triet'nyleneglycol diacetate, used alone.

This invention has been exemplified in terms of emulous similarity between color-formers of the type disclosed in the Chu et al., application and the above nonpolymeric color-formers in that both have ionizable groups and weighting groups. Fundamental considerations indicate that interaction and compatibility with gelatin occurs via said ionizable groups. Both types of couplers have such ionizable groups (carboxyl and/or sulfonate) and inherently contribute to brittleness in multilayer films and, therefore, films containing both types of color-formers may be significantly improved in a similar manner. 11- lustrative of the similarity of these two types of colorformers is the fact that the viscosity of an aqueous gelatin solution will be increased considerably by the addition of an aqueous solution of either of these types of color-formers. In contrast, no increase in viscosity of aqueous gelatin solutions is observed upon addition of that large class of color-formers of the lipophilic or organic solvent-soluble type such as disclosed in US Patents 2,108,602 and 2,126,337 and which are free of carboxyl or sulfonate groups.

The color-formers used in accordance with the invention are of high molecular weight, essentially colorless and contain as an active dye-forming or color-former nucleus, a structure of the formula:

which is a general structure of the color'coupling nucleus in an enol form.

The foregoing nuclei are found in the reactive methylene dye intermediates and in aromatic hydroxyl compounds and includes the reactive ethenol groups. These groups occur in phenols, naphthols, acylacetamides, cyanoacetyls, beta-ketoesters, pyrazolones, homophthalimides, coumaranones, indoxyls, thioindoxyls, and indazolones. Useful color-formers including those of this structure are described in US. Patents 2,758,029, 2,927,019, 2,927,024, 2,997,388, 3,070,442, in each of the patents listed therein and in the applications referred to above.

Inert ingredients, e.g., pigments, colloidal silver, matting agents, etc. may be present in all of the element layers including the support. The element may also contain chemical sensitizers, optical sensitizers, coating aids, anti-foggants, non-halation dyes and pigments, brightening agents as known to the art, etc.

With this invention it is possible to combine in a single multilayer color photographic element the advantages of the integral color-former structure (ease of processing) with the advantages of superior sharpness, definition, resolution, etc., normally associated with a non-integral color-former structure. The advantages of sharpness, etc., are not inherent in the non-integral color-former structure except inasmuch as it has been impossible, prior to the present invention, to achieve, in a satisfactory mannet, the same thinness of emulsion layers in elements containing integral color-formers.

The outstanding advantage of this invention is the improvement in flexibility attained without sacrifice in the thinness or consequent loss in resolution and sharpness. Furthermore, the improvement in flexibility is retained even at very low relative humidities since the plasticizers of this invention do not require the presence of atmospheric moisture to be effective. Other advantages of the elements of this invention include improved toughness, particularly when wet, whereby the elements are able to undergo treatment in aqueous processing solutions with excellent resistance to abrasion. With their good flexibility, the emulsions have little tendency to crack, even at low relative humidity. Mounted transparencies, prepared from these elements after exposure and photographic processing, possess a unique superiority in projection in that they do not pop due to the heat of the pro ection lamp; thus the annoying requirement of changing the focus of the projection lens is eliminated. The tendency of this film to curl at the edges has been reduced to a low level.

I claim:

1. A multicolor photographic element comprising a support bearing (1) a plurality of differentially sensitized silver halide emulsion layers, each layer being adapted to record an image from light in a difierent primary color region of the visible spectrum and containing a color former having at least one nucleus capable of forming a dye selected from the group consisting of quinoneimine, azomethine and azo dyes upon color coupling development of a silver salt image and gelatin, the color former in at least one of said layers being a gelatin-compatible, polyanionic vinyl addition polymer containing a plurality of color-forming nuclei capable of forming an aforesaid dye, said emulsion layers having an integral thickness, 6, of not more than 12.5 microns, and coated over said plurality of emulsion layers,

(2) a gelatin antiabrasion layer containing an organic plasticizer having an oxygen atom in its molecule which is doubly bonded to an atom selected from the group consisting of carbon, phosphorus and sulfur and being free from hydrogen atoms more acidic than pK =19 and having (a) a boiling point above 200 C., (b) -a melting point below 40 C., and (c) a solubility in water of at least 0.5 g. per liter at 25 C.

2. An element according to claim 1 wherein the gelatin antiabrasion layer contains a vinyl addition polymer.

3. An element according to claim 1 wherein said support embodies a melt-cast, oriented polymer film that does not absorb the plasticizer, is transparent to visible light and there is an antihalation layer between the support and the emulsion layers.

4. An element according to claim 1 wherein said element comprises three silver halide emulsion layers sensitive, respectively, to the blue, green and red regions of the spectrum.

5. An element according to claim 1 wherein said element comprises a light filter stratum which absorbs blue light and three light-sensitive silver halide emulsion layers sensitive, respectively, to the blue, green and red regions of the spectrum.

6. A multicolor support bearing (1) a plurality of differentially sensitized silver halide emulsion layers, each adapted to record images from light in a difierent primary color region of the visible spectrum and containing a water-permeable binder comprising gelatin and a gelatin-compatible polyanionic color-forming vinyl addition polymer acting as a co-binder for said silver halide crystals and containing a plurality of color-forming nuclei capable of forming a dye selected from the group consisting of quinoneimine, azomethine and azo dyes upon color-coupling development of a silver salt image, said nuclei being connected to the polyvinyl chain through an amide group, said emulsion layers having an integral thickness, 6, of not more than 12.5 microns and coated over said plurality of emulsion layers (2) a gelatin antiabrasion layer containing an organic plasticizer having an oxygen atom in its molecule which is doubly bonded to an atom selected from the group consisting of carbon, phosphorus and sulfur and being free from hydrogen atoms more acidic than pK =19 and having (a) a boiling point above 200 C., (b) a melting point below 40 C., and (c) a solubility in water of at least 0.5 g. per liter at 25 C.

7. An element according to claim 6 wherein said support is a hydrophobic film base transparent to visible light photographic element comprising a 5 55 and has an antihalation layer between the support and the emulsion layers.

8. An element according to claim 6 wherein said element comprises three silver halide emulsion layers sensitive, respectively, to the blue, green and red regions of the spectrum.

9. An element according to claim 6 wherein said element comprises a light filter stratum which absorbs blue light and three light-sensitive silver halide emulsion layers sensitive, respectively, to the blue, green and red regions of the spectrum and each color former yields a dye which is complementary in color to the utilized sensitivity of the respective layer.

10. An element according to claim 6 wherein the gelatin antiabrasion layer contains a vinyl addition polymer.

15 11. An element according to claim 10 wherein said vinyl addition polymer is polyethyl acrylate.

References Cited 7 UNITED STATES PATENTS 2,633,423 3/1953 Bower et a1. 96 87 3,178,288 4/1965 Orinik 96-87 3,211,552 10/1965 Chu et a1. 96-22 OTHER REFERENCES Zelikman et al.: Making and Coating Photographic Emulsions, The Focal Press, New York, pages 14-16 and 273-5 (1964).

J. TRAVIS BROWN, Primary Examiner,