US3539351A - Photographic gelatin hardened with an aliphatic polyoxymethylene glycol aliphatic carboxylic acid diester - Google Patents

Description

United States Patent i thee 3,539,351 Patented Nov. 10, 1970 ABSTRACT OF THE DISCLOSURE Gelatin compositions and photographic silver halide gelatin emulsions are hardened upon the alkaline activation of certain polyoxymethylene esters.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to organic materials which are particularly useful in the photographic field and to gelatin compositions containing therein a compound useful for hardening gelatin under alkaline conditions, but having little or substantially no hardening action under neutral or acidic conditions.

Description of the prior art It is desirable that a layer of gelatin in a photographic element remain on the support during processing at elevated temperatures, and this is usually done by hardening the gelatin before or during processing. Known hardening substances have been incorporated in gelatin compositions, but many of these have produced undesirable sensitometric effects when contacted with photographic emulsions, as well as producing substantially immediate hardening thus increasing processing times. Formaldehyde, for instance, has shown adverse sensitornetric characteristics in contact with certain highly sensitized photographic emulsions. Other hardeners have exhibited tendencies to fog and otherwise create objectionable sensitornetric effects. Still other hardeners produce an immediate hardening effect upon their incorporation into the photographic emulsion, or upon aging or storage.

Gates and Rees, U.S. Pat. 3,110,597, issued Nov. 12, 1963, discloses as potential gelatin hardeners, compounds containing the acyloxy moiety, which compounds affect the gelatin emulsion upon contact with liquids exhibiting an alkaline effect. This reference, however, shows only mono-oxymethylene esters which require a halogenated acid moiety. We have found that in our novel compositions containing our blocked hardening agents, polyoxymethylene diesters provide results superior to those afforded by the monooxymethylene esters.

SUMMARY OF THE INVENTION According to our invention we have now found that compositions comprising a hardenable material such as a proteinaceous material, for example, gelatin and more particularly gelatin silver halide emulsions, are satisfactorily hardened by activating certain blocked-hardeners during processing. These hardeners are aliphatic polyoxymethylene diesters which are particularly effective under alkaline conditions to harden protein and, in photographic binders, are capable of delivering rapid image formation.

DESCRIPTION OF PREFERRED EMBODIMENTS Our invention is accomplished by adding an aliphatic polyoxymethylene glycol aliphatic carboxylic acid diester to a hardenable material, for example, proteinaceous materials such as gelatin, gelatin derivatives and the like. The term gelatin as used in our invention includes not only gelatin, per se, but gelatin mixtures and derivatives as hereinafter described.

The aliphatic polyoxymethylene glycol-carboxylic acid diesters of our invention include those having the following formula:

in which R is lower alkyl (e.g. alkyl of 1 to 3 carbon atoms), or haloalkyl and n is in integer of from 2 to 20. Typical alkyl groups include methyl, ethyl, n-propyl, isopropyl, and haloalkyl groups such as chloromethyl, chlo roethyl, trichloromethyl, etc. Compounds of the above general formula can be prepared as previously described in the literature.

In accordance with this invention it has been found that our diesters can be used to treat hardenable materials such as hydrophilic colloids as exemplified by gelatin. In alkaline media the binding agents in photographic materials are hardened by the compounds of this invention. The hardening, or crosslinking, effect occurs between the hardenable material and an aliphatic polyoxymethylene glycol aliphatic carboxylic acid diester of the invention. In another aspect of this invention, we have found a method of hardening a hardenable material which comprises treating said material with a compound having the formula disclosed above. This hardenable material can comprise a layer on a support in a photographic element, for example, the layer can comprise a photographic silver halide emulsion.

The hardening effect is thus substantially delayed or blocked and appears concurrently with processing and during the image development stage. This results in a re duced time required for processing, a diminution of deleterious sensitornetric elfects and less destruction of the generated hardening substance in the alkaline processing medium. Where gelatin is used in the composition as the binding agent for photographic emulsions, a useful range of blocked hardener is from 0.5 to 10 percent, based on the weight of the gelatin. Activation of the blocked hardener occurs preferably at a pH of about 10, a useful range being about 7 to 14.

As will be understood by those skilled in the art, no essential factors exist for obtaining a suitable pH. For example, the pH can be adjusted prior to, during or after the addition of the hardening compounds to the hardenable material.

The following examples are illustrative of the invention, but other similar compounds may be used both singly, and in combination as hereinafter shown.

Although frequently obtained in mixtures, the compounds of the invention can be fractionally distilled in many cases into substantially pure esters and used as such.

Example I.A preparation of dioxymethylene diacetate is effected following the procedure described by Tomiska and Spousta, Angew. Chem. 74, 248 (1962) for reacting s-trioxane with acetic anhydride. The dioxymethylene diacetate was recovered having a boiling point of approximately 54-56 C. (0.7 mm.).

Example II.In the same procedure as shown in Example I, there is also recovered trioxymethylene diacetate, possessing a boiling point of approximately 62-63" C. (0.07 mm).

Example lII.According to an adaptation of Standinger et al., Ann. 474, (1929) a mixture of paraformaldehyde and acetic anhydride is heated at C. for approximately 1 /2 hours. The soluble portion of this product is extracted with ether, the latter then evaporated,

and the residue taken up in ethyl acetate. Upon distillation of this solution, several fractions are recovered, each of which consist chiefly of a twoor three-component mixture of polyoxymethylene diacetates.

(A) Distillation at a pot temperature of 99 C. (4n) (all of the remaining values for vacuum area in microns ,to) produce a composition consisting of approximately 14 percent tri-, 63 percent tetraand 23 percent pentaoxymethylene diacetates which is indicated by vapor phase chromatography.

(B) Continued distillation of the above solution in Example HI produces another fraction at 115 C. (4 which is found to consist of approximately 55 percent pentaand 44 percent hexaoxymethylene diacetate.

(C) Distillate fractions detected at about 152 C. (7 consist of about 45 percent hexaand 53 percent heptaoxymethylene acetates.

(D) The last distillate fraction from the reaction of Example III (above) is recovered at a pot temperature of 168 C. (4n) and is a low melting, semi-crystalline solid. Chromatographic identification means result in identifying approximately 31 percent heptaand 69 percent octaoxymethylene diactetates.

Example IV.Mono-oxymethylene diacetate is obtained by fractionation of the forerun obtained in Example III; B.P. 65 mm.).

Example V.Dodeca(oxymethylene)diacetate is ob- 4 semi-solid extracted with ether. Fractionation of the ether extracts produce several fractions, one of which proves to be his (chloroacetoxy)rnethane with a boiling point of 66-68 C. (1 n 1.4662.

The structure is confirmed by elementary analysis and by the nuclear magnetic resonance spectrum.

Example VIII.A higher boiling fraction from the ether extracts of Example VII which solidifies, is recrystallized from ether. This fractions structure is shown by elementary analysis and by nuclear magnetic resonance to be that of octa(oxyrnethylene)-bis-(chloroacetate).

It was found that similar compounds, containing the mono-oxymethylene group (where n is one) rather than the polyortymethylene ester, upon incorporation into a gelatin composition, and more particularly, a silver halide photographic gelatin emulsion, provided substantially no hardening either immediately or upon immersion in an alkaline medium.

The compounds prepared in the preceding examples were added to separate portions of a high-speed silver bromoiodide emulsion panchromatically sensitized with a cyanine dye. Each emulsion sample was coated on a cellulose acetate film support at a coverage of 432 mg. of silver and 980 mg. of gelatin per square foot. A sample of each film coating was exposed on an Eastman IB sensitomere, processed for five minutes in Kodak D-l9 developer, and dried with the following results:

Sensitometric data, fresh Percent swell Rel. Wash Compound used Percent 1 speed Gamma Fog Dev. Fix water Control 100 1. 18 13 600 390 650 Dioxymet-hylene diaeetate 6 102 1. 12 380 260 410 Trioxymethylene diacetate 6 112 1. 23 11 350 240 360 Mono-oxymethylene diaeetate 6 112 1. 11 540 350 590 Control. 100 1. 57 16 460 320 510 Mixed trl-tet-ra and pentaoxymethyleno d1- acetates 6 89 1. 43 13 360 260 410 Mixed pentaand hexaoxy-methylene diacetates 6 89 l. 37 13 380 250 400 Mixed hexaand heptaoxy-methylene diaeetates 6 94 1. 48 13 350 250 390 Mixed heptaand octaoxy-methylene diaeetates 6 100 1. 57 14 380 260 420 1 Based on weight of dried gelatin.

Similarly, other examples previously cited give the same good hardening results in the absence of deleterious sensitornetric effects.

In a similar series of experiments, in which the developer used was Kodak DK-SO, the following results were obtained:

Sensitometric data, fresh Percent swell Wash Compound used Percent 1 Speed Gamma Fog Dev Fix water Control 100 1. 22 l4 1, 400 580 910 1 147 1. 3O 14 1, 100 490 790 Dioxymethylene diacetate. 3 297 1. 27 14 960 440 670 6 95 l. 23 l4 1, 510 710 Trioxy-methylene diacetate 3 94 1. 23 13 830 360 570 6 97 1. 23 14 900 420 620 Monooxymethylene diacetate 3 1. 32 14 1, 300 540 880 6 102 1. 32 14 1, 200 490 800 1 Based on weight of dried gelatin.

Example Vl.From the ether extraction of Example V, a residue is extracted with chloroform at 25 C. Upon evaporation and recrystallization from the chloroform, a colorless solid extract is produced having a melting point of 98100 C. This solid is heptadeca(oxymethylene)diacetate (Staudinger et a1. reports 98.599.5 C. for this compound.)

Example VII.Bis(chloroacetoxy)methane is produced as folows: A mixture of 300 parts of chloroacetic anhydride and 265 parts of paraformaldehyde is heated at C. for 1 hour in a stirred autoclave. The reaction The silver halides employed in the photographic emul- 65 sions include any of the photographic silver halides, as

exemplified by silver bromide, silver chloride, silver chlorobromide, silver bromoiodide and the like. The silver halides used can be those which form latent images predominantly on the surface of the silver halide grains or those which form latent images inside the silver halide crystals such as described in U.S. =Pat. 2,592,250 of Davey and Knott issued Apr. 8, 1952.

Photographic emulsions of the present invention can contain antifogging and stabilizing agents and can be product is washed with petroleum ether and the residual 75 sensitized using any of the well-known techniques in emulsion making, for example, by digesting with naturally active gelatin or various sulfur compounds and/or gold compounds. The emulsions may be sensitized with salts of novel metals of Group VIII of the Periodic Table which have an atomic weight greater than 100. The emulsions can also be sensitized with labile selenium and noble metals as disclosed in US. Pat. 3,297,446 of Dunn issued Jan. 10, 1967. The emulsions may also contain speed-increasing addenda such as quaternary ammonium salts, polyethylene glycols, or thioether sensitizers.

The emulsions of the invention may also contain conventional additives such as gelatin plasticizers, additional hardeners and coating aids. These emulsions may be used in X-ray and other non-optically sensitized emulsions, and may also be used in ortho-chromatic, panchromatic and infrared sensitive emulsions. The additives may be added to the emulsion before or after sensitizing dyes, if any, are used.

The emulsions may be used in photographic elements intended for color photography, and thus may contain color-forming couplers, or used as emulsions to be developed by solutions containing couplers or other colorgenerating materials, or emulsions of the mixed-packet type, as disclosed in US. Pat. 2,698,794 of Godowsky issued Jan. 4, 19 55, or emulsions of the mixed-grain type, such as disclosed in US. Pat. 2,592,243 of Carroll and Hanson issued Apr. 8, 1952.

The emulsions obtained in accordance with this invention may be used in diffusion transfer processes which utilize the undeveloped silver halide in non-image areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a silver layer in close proximity to the original silver halide emulsion layer. Such processes are described in US. Pats. 2,352,014 of Rott issued June 20, 1944; 2,543,181 of Land issued Feb. 27, 1951; and 3,020,155 of Yackel et al. issued Feb. 6, 1962. The emulsions may also be used in diffusion transfer color processes which utilize a diffusion transfer of an imagewise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another.

A wide variety of emulsion vehicles and dispersing agents for silver halide grains may be employed singly or in combination with each other, for example, gelatin, colloidal albumin, cellulose derivatives and synthetic resins, such as polyvinyl compounds. The blocked hardeners of this invention are effective with polymeric substances used in combination with gelatin in photographic emulsions, or otherwise as noted in Smith application U.S. Ser. No. 525,272, filed Dec. 20, 1965 US. Pat. 3,459,790. Also, our blocked hardeners can be used with gelatin derivatives, such as those described in Yutzy and Frame US. Pat. 2,614,928, issued Oct. 21, 1952. Examples of typical colloids which may be used are poly(vinyl alcohol), hydrolyzed poly(vinyl acetate), hydrolyzed cellulose ester, water-soluble ethanolamine cellulose acetate, polyacrylamide, copolymers having a combined acrylamide content of 3-60 percent, copolymers of alkyl acrylate and acrylic acid, a vinyl alcohol copolymer containing urethane carboxylic acid groups or containing cyanoacetyl groups, or polymeric material which results from polymerizing a protein or saturated acrylated protein with a monomer having a vinyl group such as disclosed in US. Pat. 2,852,382 of Jones issued Sept. 16, 1958. Such polymeric additives may be employed as latices or hydrosols in the preparation of the photographic emulsions of our invention.

The photographic emulsions can be coated on a wide variety of supports, preferably supports which are transparent and/or flexible. Typical supports include metals such as aluminum, paper, cellulose acetate film, polyvinyl acetate film, polystyrene film, polypropylene film and other polyolefin film, polycarbonate film, polyethylene terephthalate or other polyester film and other related materials. Supports such as paper which are partially acetylated or coated with an alpha-olefin polymer particularly a polymer of an alpha-olefin containing 2-10 carbon atoms, as exemplified by polyethylene, polypropylene, ethylenebutene copolymers and the like, give good results.

Further these agents can be used in the preparation of various subbing layers for silver halide emulsions, interlayers, filter layers or in overcoat layers.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described hereinbefore and as defined in the appended claims.

We claim:

1. A gelatin containing composition comprising a hardening concentration of an aliphatic polyoxy-methylene glycol aliphatic carboxylic acid diester.

2. A gelatin composition containing in hardening concentration therein a polyoxymethylene diester having the structure:

in which R is lower alkyl being unsubstituted or containing a halogen substituent, and n is an integer of from 2 to 20.

3. A gelatin silver halide photographic emulsion comprising therein a hardening concentration of a polyoxymethylene diester having the structure:

in which R is lower alkyl being unsubstituted or containing a halogen substituent, and n is an integer of from 2 to 20.

4. The emulsion described in claim 3 wherein R is methyl and n is 2.

5. The emulsion described in claim 3 wherein R is methyl and n is 3.

6. The emulsion described in claim 3 wherein R is methyl and n is 4.

7. The emulsion described in claim 3 wherein R is methyl and n is 5.

8. The emulsion described in claim 3 wherein R is methyl and n is 6.

9. The emulsion described in claim 3 wherein R is Ris in which R is lower alkyl being unsubstituted or containing a halogen substituent, and n is an integer of from 2 to 20.

(References on following page) 7 8 References Cited NORMAN G. TORCHIN, Primary Examiner UNITED STATES PATENTS R. E. FICHTER, Assistant Examiner l. 29 3,110,597 11/1963 Gates at a 96 X Us. CL XlR 3,442,654 5/1969 Eiseman et a1 96114X 3,471,297 10/1969 Sprung 96-107 5 106-125; 260117