US3100704A - Photographic materials containing carbodhmides - Google Patents

Description

United States Patent O \a Delaware lfl'o Drawing. Filed July 24, 1958, Ser. No. 750,590

17 Claims. (Cl. 96-111) This invention relates to photography, and particularly, to photographic gelatin layers and light-sensitive photographic gelatin emulsion layers containing the quaternary ammonium salts of an N,N'-d=isubstituted carbodiimide as a hardening agent.

Gelatins used in the production of photographic materials have been reacted with a variety of hardening and modifying agents such as alum, chrome alum; formaldehyde, glyoxal :or other aldehydes; keto-alcohols, nitroaldehydes, nitroureas, and the like to improve the physical characteristics of the gelatins. In all cases, however, the reagents react with the gelatin to yield a derivatized gelatin containing the reagent or a part thereof as an integral part of the gelatin structure With the result that some questionable improvement in physical properties is accompanied by an impairment of photographic properties.

It is an object of our invention to prepare hardened photographic gelatin layers, having improved physical and photographic characteristics.

Other objects will be apparent from the following description.

We have found that compositions of matter adapted to form hardened gelatin layers including gelatin silver halide emulsion layers can be prepared by using the products resulting from the addition to an aqueous gelatin solution of a small portion of a quaternary ammonium salt of an N,N-disubstituted carbodiimide. These layers have new and improved properties, display unique characteristics and differ from unreacted gelatin and silver halide emulsion layers by their melting points and photographic characteristics.

The water or alcohol soluble quaternary ammonium salts of the N,N'-d-isubstituted carbodiimdes used in accordance with this invention are characterized by the following general formulae:

wherein A represents an organic radical such as an aliphatic radical, e.g., methyl, ethyl, propyl, isopropyl, nbutyl, isobutyl, tert.-butyl, allyl, crotyl, B-hydroxyethyl, methoxy-methyl-B-bromoallyl, and the like; an aromatic radical, e.g., phenyl, tolyl, Xylyl, naphthyl, chlorophenyl, bromophenyl, iodophenyl and the like; and alicyclic radical, e.g., cyclohexyl, bornyl, menthyl and the like; and a heterocyclic radical, e.g., pyridyl, quinolyl and the and ice

like; R and R are lower alkyl radicals, e.g., methyl, ethyl, propyl, isopropyl, butyl and the like; B and B which may be alike or different represent alkylene, arylene or aralkylene radicals, e.g., propylene, phenylene, tolylene, propylphenylene and the like; X is an anion, e.g., chloride, bromide, iodide, methosulfate, ethosulfate, p-toluenesulfonate; and n is a positive integer not greater than 2.

The disubstituted carbodiimides are prepared by treating an N,N-disubstituted symmetrical or unsymmetrical thiourea, having at least one tertiary amino group, with a desulfurizing agent, particularly the oxide of a heavy metal such as lead or mercury, as described in Berichte, vol. 71, pages 1512-21; vol. 73, pages 467-477, 1114 1123; vol. 74, pages 12851296 and vol. 75, pages 100-5; Annalen, vol. 560, pages 222-231; also Journal of Organic Chemistry, vol. 21, pages 1024-6.

The N,N'-disubstituted carbodiimides with the tertiary amino group are converted into the quaternary ammonium salt by reacting them directly, or in the presence of a solvent-diluent such as ethyl acetate, chloroform, benzene, or toluene, or mixtures thereof, with a suitable quaternizing agent such as methyl bromide, ethyl bromide, methyl iodide, ethyl iodide, dimethyl sulfate, diethyl sulfate, methyl p-toluene sulfonate, ethyl p-toluene sulfonate and the like. Molar equivalents of the quaternizing agent or a slight excess thereof are employed if only one of the tertiary nitrogen atoms is to be quaternized while di-molar equivalents are used when two tertiary amino groups are to be converted into the quaternary forms. i

The following is a suggestive listing of N,N-disubstituted carbodiimides which may be employed for the purpose herein set forth: N-is opropyl-N'- 4-dimethylaminophenyl) carbodiimide ethyl p-toluenesulfonate N-phenyl-N-(4-dimethylaminophenyl)carbodiimide ethyl p-toluenesulfonate N,N-di(4-dimethylaminophenyl) carbodiimide rnonoethobromide N,N-di(4-dimethylaminophenyl) carbodiimide monoethiodide N,N'-di(4-dimethylarninophenyl)carbodiimide dimethiodide N,N-di(4-diethylaminophenyl)carbodiimide methyl ptoluenesulfonate N,N'-di(4-dipnopylaminotolyl)carbodiimide ethyl p-,

toluenesulfonate N,Nt-di(4-dimethylaminophenyl)carbodiimide mono- 'tion products.

N-isopropyl-N'- ('y-dimethylaminopropyl) carbodiimide ethobromid e N-methoxymethyl-N- (v-d imethylaminopropyl) carbodiimide ethyl p-toluenesulfonate N,N'-di-('y-pyridyl)carbodiimide monomethosulfate N,N-dl- ('y-pyridyl carbodiimide di'ethosulfate The reaction between the gelatin (bone, hide, pigskin or degraded, etc.) and the carbodiimide'can be carried out by dissolving or swelling the gelatin in water and then adding the quaternary ammonium salt of the carbodiimide in any convenient inert solvent media, preferably water, alcohol, or mixtures thereof.

The gelatin'concentration may vary over a wide range, e.g., from 0.5 to 20 percent by weight. The amount of carbodiimide quaternary ammonium salt employed in the reaction may range from gms. to 50 gms. per kg. of dry gelatin although amounts ranging from to 25 gms. of carbodiimide per kg.'of dry gelatin are preferred. The reaction temperature may be varied from 5 C. to 75 0, preferably from to 50 C., but care must be taken to avoid prolonged heating at such higher temperatures at which the gelatin becomes unstable. The

pH may be varied through the mildly acid or mildly alkaline range although a pH between 5 and 8 has been found most suitable in aqueous systems.

The gelatin solutions and photographic emulsions which have been hardened with the carbodiimide quaternary salts yield products which have valuable properties. They yieldphotographic films which have higher melting points and which are less affected by storage and processing at elevated temperatures. The viscosity of the gelatin solution containing the carbodiimide is not increased on holding prior to coating, so that no compensation must be made to correct for constantly increasing viscosities'prior to and during the coating operation. Most important is several. It will be observed that this reaction differs entirely from the type of modification of gelatin obtained by the use of conventional hardeners such as formaldehyde, keto-alcohols, etc., because the latter enter the gelatin molecule or form the cross-links which bind the gelatin molecules.

The materials obtained by our procedure can be further modified by the use of external acids such as acetic,.

butyric, stearic, or other aliphatic acids; by benzoic, toluic, or other variously substituted aromatic acids; or by alicyclic or heterocyclic carboxylic acids. These acids are caused to react with the amino groups of gelatin by the use of carbodiimides as condensing agents. The reaction is analogous to those which occur when carbodiimldes are mixed with gelatin alone, and the reaction products are assumed to have the following general formula:

Gel-NH-COR Gel-O ON wherein R and R are hydrogen or hydrocarbon radical the feature that emulsions hardened with our quaternary salts do not cause the undesirable effects known as after hardening but reach a'stabilized melting point within a few days of storage at room temperature.

Our procedure offers special advantages when applied to gelatins which contain substantial amounts of degrada- Such materials frequently have desirable photographic properties, but cannot be used commercially in view of their poor physical properties. Such gelatins can be substantially improved with our process through relinking of the degradation products to the parent gelatin molecules. More particularly, gelatin samples which conand constitutes the residue of the amine used in the reaction.

Our invention includes in one of its preferred forms the use of carbodiimide quaternary ammonium salts in conjunction with conventional gelatin hardeners such as formaldehyde, glyoxal, glycol aldehydes, diketones, halogen-substituted aldehyde acids such as mucochloric acid and mucobromic acid, formylacrylic acid, glyoxylic acid, halogen-substituted ketones such as chloroacetone,

'; dichloroacetone or dibromoacetone, hydroxy-substituted ketones such as dihydroxyacetone, amino aldehydes, nitro aldehydes, nitro alcohols and the like. In this case, the effects induced by the use of the carbodiimide quaternary ammonium salts and the effects produced by the hardeners supplement each other and are of a synergistic nature.

7 Thus, different properties may be obtained, or considertain substantial amounts of degradation products are characterized by depreciated properties, such as lowered melting points and setting points, decreased rigidity moduli (meaning the resistance of gelatin gels to deformation) increased Bloom value (measuring the resistance of the surface to penetration) as described in the Encyclopedia of Chemical Technology, vol. VII, page 151 (1951) increased brittleness and increased watersolubility. These deficiencies are ameliorated by the treatment with carbodiimides.

The reaction between the gelatin is believed to be attained in such-a way that the carbodiimide may serve solely as a condensing or cross-linking agent as illustrated by the following hypothetical general equation in which'the symbol gel represents the residue of a gelatin molecule for reasons of simplicity:

carbodiimide quaternay HaN-Gel-C 0213 HzN-Gel-O O OH 7 ammonium salt Since gelatin contains both free amine and free carboxyl groups, this type of reaction may be either an intraor intermolecular condensation. Only gelatin molecules are involved in cross-linking. Obviously, this reaction need not stop with two gelatin molecules but can involve and the carbodiimide ably lower amounts of hardening agents may be employed to achieve the desired physical properties. The reaction with formaldehyde in the presence of carbodiimide quaternary ammonium salts is believed to proceed as follows:

- HzN-Gel-OONH-Gel-COOH lumen-coon H0110 0% I HzN-GQON-Gel-GOOH The amounts of aldehyde or other organic hardener used in this combination hardening will yary between 1 and 8 grams of aldehyde per kilogram of gelatin depending on the aldehyde chosen and the degree of hardening desired. In any event the amount of organic hardener used in combination hardening Will not exceed 50 percent of that amount needed to produce the selected degree of hardening when the organic hardener is used by itself.

While the above reactions have been illustrated with respect to the carboxy and amino groups of the gelatin molecules, it should be kept in mind that these molecules contain additional functional groups such as guanidino, aliphatic or aromatic hydroXyl, mercapto or disulfide linkages which may enter new bondings in the reaction. It is, therefore, evident that the aforementioned illustrations are of an explanatory nature only andshould not be construed as limiting the invention to these mechanisms.

The following examples will serve to illustrate the previously described invention, although it is to be understood that the invention is not to be limited thereto.

Melting Melting Mg. f carbodilmide salt per g. of gel. point, 0. point, 10

days, C.

The photographic properties of the material which contained 30 milligrams of carbodii-mide salt per gram of gelatin which did not melt at 90 C. were compared with the photographic properties of an unhardened emulsion and of a formaldehyde hardened emulsion. The following results were obtained:

Fog Speed Contrast High speed negative Fresh Aged Fresh Aged Fresh Aged Unhardened 0. 19 0.26 110 03 1. 5 1. 4 Formaldehyde. 0. 17 0. 24 93 79 1. 5 1. 4 Oarbodiimide 0. 12 0. 25 135 123 1. 5 1. 4

It will be noted that the use of carbodiimide hardener increased the speed of this film by about twenty percent. The speed advantage was retained in the aged film. Other photographic properties were not affected. The film hardened with formaldehyde showed a speed loss of about 20 percent.

EXAMPLE II Example I was repeated with the exception that a 2 percent solution of N-cyclohexyl-N-(4-dimethylaminophenyl)carbodiimide ethyl p-toluenesulfoniate was used in place of the N,N-di(4-diethylaminophenyl)carbodiimide methyl p-toluenesulfonate. The following results were obtained:

Melting Melting Mg. earbodiimide/g. gel. point, 0. point,

ays,

The photographic results obtained were similar to those reported in Example 1. Contrast and fog were essentially unchanged while the speed was noticeably increased. An emulsion hardened with formaldehyde showed loss of speed, contrast and increased fog.

EXAMPLE III A high speed X-ray emulsion containing 8 percent gelatin was mixed with increasing amounts of a 2 percent aqueous solution of N-(tert.-butyl)-N'-(' -dimethylaminopropyl)carbodiimi-de ethyl p-toluenesulfonate and then coated on filmbase. fter coating, the samples were 6 stored over saturated K solution for three days. The following results were obtained:

Melting Melting Mg. earbodiimide/g. gel. point, 0. point, 3

days, C.

The photographic properties of the emulsion. containing 30 mg. of carbodiimide per gram of gelatin were compared with an unhardened type and a film hardened with formaldehyde. The following results were obtained:

Table I Fog Speed Contrast High speed negative Fresh Aged Fresh Aged Fresh Aged Unhardened type 0.10 0.16 107 110 1.7 1.4 Formaldehyde hardened- 0.11 0.17 102 85 1.6 0.6 Carbodiirnide hardened 0.12 O. 17 120 1.7 1.4

The significantly improved aging behavior of the cardodiimide hardened films with respect to speed and contrast is evident.

EXAMPLE IV Coatings were made as in Example I using both N,N'- di(4 diethylaminophenyl)carbodiirnide dimethosulfate and formaldehyde in various amounts. The following melting points were observed:

Mg. ear- Mg. torm- Melting Melting bodiirnide/ aldehyde] point, 0. point, 10

g. gel. g. gel. days, C.

0 None 34. 7 35.1 10 None 40.1 41. 5 None 1 37. 5 38. 9 None 3 37. 9 39. 3 None 6 41. 3 52. 7 10 1 39. 5 45. 7 10 3 40. 5 62. 2 10 6 50. 2 90+ It will he noted from this table that the synergistic effect resulting from the combined use of formaldehyde and carbodiimide in raising the melting point of the coating is very pronounced.

EXAMPLE V Example IV was repeated with the exception that N- cyclohexyl-N-(4-dimethylaminophenyl) carbodiimide ethyl p-toluenesulfonarte was used in place of N,N-di(4-diethylaminophenyl) carbodiirnide dimethosulfate. The following results were obtained:

Mg. ear- Mg. glyoxal/ Melting bodiimlde/ g. gel. point, G.

g. gel.

0 None 34. 9

10 None 36. 2

20 None 39. 5

30 None 40. 7

None 1 36. 4

None 2 39. 3

None 4 41. 9

Thus, a level of carbodiimide which was insufiicient by itself to appreciably harden the emulsion coating, was eifec-tive as a hardener when combined with a glyoxal which by itself was also incapable to appreciably harden the emulsion coatings. The photographic properties of 7 the film hardened with the combination of formaldehyde and carbodiimide were excellent. Even after extended storage, no loss of speed and contrast was observed, a positive indication that the undesirable photographic effects of after hardening were obviated.

.Various modifications of this invention will occur to persons skilled in the art. We, therefore, do not intend to be limited in the patent granted except as necessitated by the appended claims. For instance, in place of the formaldehyde and the glyoxal illustrated by the examples, other known hardening agents can be used.

This application is a continuation-impart of our application, Serial No. 609,529, filed September 13, 1956, now abandoned.

We claim:

1. A silver halide emulsion adapted to form a hardened layer comprising a gelatin silver halide photognaphic emulsion containing (a) a member selected from the group consisting of:

and

R2 \NB-N=C=N-B1N wherein A represents members selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, isobu-tyl, tert.-butyl, allyl, crotyl, be-tahyd-roxyethyl, methoxymethyl-beta-bronioal-lyl, phenyl, tolyl, Xylyl, naphthyl, chlorophenyl, bromophenyl, iodophenyl, cyolohexyl, bornyl, menthyl, pyridyl and quinolyl; R and R represent lower alkyls; B and B represent members selected from the group consisting of propylene, phenylene, tolylene and propylphenylene, X is an anion selected from the group consisting of chloride, bromide, iodide, methosulfate, ethosu-lf ate, p-t-oluene sulfonate and n is a positive integer not greater than 2, and (b) an organic hardener selected from the group consisting of formaldehyde, glyox'al, glycol aldehydes, diketones, mucochloric acid, mucobromic acid, formylacrylic acid, glyoxylic acid, ohloroacetone, dichloroacetone, dibromoacetone, dihydroxyacetone, amino aldehydes, nitro aldehydes and nitro alcohols.

2. A composition of matter comprising a solution of gelatin containing (a) a member selected from the group and selected from the group consisting of formaldehyde, glyoxa l, glycol aldehydes, diketones, mucochloric acid,

mucobroniic acid, formylacrylic acid, glyoxylic acid, chloroacetone, dichioroacetone, dibromoacetone, dihydroxy acetone, amino aldehydes, nitro aldehydes, and nitro alcohols.

3. A gelatin silver halide light emulsion as defined by claim 1 wherein the hardening agent of (b) is glyoxal.

4. A gelatin silver halide light emulsion as defined by claim 1 wherein the hardening agent of (b) is formaldehyde.

5. A composition of matter according to claim 2 wherein the hardening agent of (b) is formaldehyde.

6. A method of producing a hardened gelatin silver halide emulsion layer in the photographic element which comprises uniformly mixing with an aqueous gelatin silver halide emulsion a hardening amount of (a) a member selected from the group consisting of:

R2 and R2 I: NB-N=o:NBiN

wherein -A represents members selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert.-butyl, allyl, crotyl, beta-hydroxyethyl, methoxymethyl-zbeta-bromo-allyl, phenyl, tolyl, Xylyl, naphthyl, chlorophenyl, bromophenyl, iodophenyl, cyclohexyl, bornyl, menthyl, pyridyl and quinolyl; R and R represent lower alkyls; B and B represent members selected from the group consisting of propylene, phenylene, tolylene and propylphenylene, X is'an anion selected from the group consisting of chloride, bromide, iodide, methosulfate, ethosulfate, p-toluene sulfonate and n is a positive integer not greater than 2, and (b) an organic hardener selected from the group consisting of formaldehyde, glyoxal, glycol aldehydes, diketones, mucochloric acid, mucobromic acid, formylacrylic acid, glyoxylic acid, chloroacetone, dichloroacetone, dibromoacctone, dihydroxy acetone, amino aldehydes, nitro aldehydes and nitro alcohols and coating said emulsion on a support and drying the layer just formed.

7. A method according to claim 6 wherein the hardener of (=b) is formaldehyde.

8. A method according to claim 6 wherein the hardener of (b) is glyoxal.

9. A silver-halide emulsion as defined by claim 1, wherein said quaternary ammonium salt is N,N'-di(4- diethylaminophenyl)carbodiimide methyl p-toluenesuldonate.

10. A silver-halide emulsion as defined by claim 1, wherein said quaternary ammonium salt is N-cy-clohexyl- N'-(4-dimethylaminophenyl) carhodiimide ethyl p-toluenesulfonate.

11. A silver-halide emulsion as defined by claim 1, wherein said quaternary ammonium salt is N-(tert.butyl)- N ('y di-methylaminopropyl) carbodiimide ethyl p-toluenesulfonate.

12. A composition of matter as defined by claim 1, wherein said quaternary ammonium salt is N,N-di(4- diethylaminophenyl)carhodiimide methyl p-toluenesultonate.

13. A composition of matter as defined by claim 1, wherein said quaternary ammonium salt is N-cyclohexyl- N'-(4-dimethylaminophenyl)carbodiimide ethyl p-toluenesulfonate.

14. A composition of matter as defined by claim 1, wherein said quaternary ammonium salt is N-(tert.- butyl) N ('y dimethylaminopropyl)carbodiimide ethyl p-toluenesulfonate.

15. A method of producing hardened silver-halide emulsion layers as defined by claim 6, wherein said quaternary ammonium salt is N,N'-di(4-diethylaminophenyl)carhodiimide methyl p-toluenesulfonate.

16. A method of producing hardened silver-halide emulsion layers as defined by claim 6, wherein said 5 quuaternary ammonium salt is N-(tert.-buty1)-N'-(' dimethylaminopropyl)carbodiimide ethyl p-toluenesulfonate.

1 ii) 1 Referenees Cited in the file of this patent UNITED STATES PATENTS 2,288,226 Carroll et a1 June 30, 1942 2,726,162 Allen et a1. Dec. 6, 1955 2,938,892 Sheehan May 31, 1960 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,100,704 August 13, 1963 Robert F. Coles et 31.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 20, strike out "High speed negative"; column 8, lines 15 to 18, the formula should appear as shown below instead of as in the patent:

same column 8 lines 59, 63 and 6'7, for the claim reference numeral "1, each occurrence, read 2 column 9, line 6, for "quuaternary" read uaternary Signed and sealed this 30th day of June 1964.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J BRENNER Attesting Officer Commissioner of Patents

Claims (1)

1. A SILVER HALIDE EMULSION ADAPTED TO FORM A HARDENED LAYER COMPRISING A GELATIN SILVER HALIDE PHOTOGRAPHIC EMULSION CONTAINING (A) A MEMBER SELECTED FROM THE GROUP CONSISTING OF: