US2732316A

US2732316A - Hardening of gelatin

Info

Publication number: US2732316A
Authority: US
Priority date: 1952-12-03
Publication date: 1956-01-24
Anticipated expiration: 1973-01-24
Also published as: FR1088876A; GB749326A

Description

United States Patent HARDENING 0F GELATIN George July, Edward Bowes Knott, and Felix Pollak, Wealdstone, Harrow, England, assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey 1 5N0 Drawing. Application December 3, 1952,

Serial No. 323,924

7 Claims. (Cl. 117-62) This invention relates to the hardening of gelatin particularly in photographic emulsions with 1:3-dihydroxymethylbenzimidazol-Z-ones.

In the case of gelatin which is to be treated with aqueous solutions, as exemplified by photographic emulsions which are treated with'processing solutions, it is particularly desirable that the gelatin have properties whereby it is resistant to the effects of the aqueous solution. It is a particular advantage if the gelatin material is not only resistant to water at normal temperature but to water at elevated temperatures because in the case of photographic emulsions resistance to hot water would permit the hot processing of the gelatin emulsion thus shortening the time for the processing operations.

One object of our invention is to provide a gelatin which is resistant to the effect of water at elevated temperature. Another object of our invention is to provide gelatin photographic emulsions which may be hot processed without break down of the physical structure thereof. A further object of our invention is to provide compositions of gelatin in which a small amount of a 1:3- dihydroxymethylbenzimidazol-Z-one is present therein. Other objects of our invention will appear herein.

We have found that when gelatin is treated with a 1:3- dihydroxymethylbenzimidazol-Z-one, or any gelatin layers or photographic gelatin emulsion layers are treated with a 1:3-dihydroxymethylbenzimidazol-2-one, the resulting product is resistant to the effect of hot water or of hot aqueous processing solutions and that in the case of photographic emulsions so treated higher speed and gamma are obtained than with emulsions not so treated and having equal fog characteristics or where equal development times are used higher speed and gamma and lower fog characteristics are obtained than for emulsions not so treated. We have found that gelatin hardened in accordance with our invention is useful either in color photography or in black-and-white photography.

The hardeners which are-employed in accordance with our invention have the structural formula:

(IJH2OH Where R is either hydrogen, alkylor a halogen substituent. Qompoundsof this type may be prepared as illustrated by the following examples.

Example 1 benzimidazol-Z'fo'ne was obtained melting at 163-464 C.

$332,316 C6 Patented Jan. 24, 1956 Example 2 i 2 parts of 5-methylbenzimidazol-2-one was mixed with 10 parts of water and 5 parts of 40% formalin and the mixture was slowly warmed so as to dissolve the solid material therein. The solution thus formed was filtered and cooled to 0 C. which resulted in the formation of pale orange, sandy crystals. These crystals were separated from the liquid and recrystallized from hot water. 2 parts of 1:3-di(hydroxymethyl)-5-methyl-benzimidazol- 2-one melting at 176-178 C. was obtained.

In the carrying out of our invention the gelatin may be hardened either by incorporating hardener directly in the gelatin, or layers of gelatin which have been coated out onto a support may be treated with a solution of the hardener so as to impart a hardening eflect thereto. The hardening action on the gelatin in accordance with our invention takes place to the best effect at a pH value of at least 8. Although the hardener in accordance with our invention modifies the properties of the gelatin when employed therewith in any proportion, we have found that amounts of the hardener within the range of .1-10% based on the weight of the gelatin are the most desirable in carrying out the hardening of gelatin in accordance with our invention. In the compounds'employed for hardening in accordance with our invention the benzene ring therein may either be unsubstituted except for the imidazole ring thereon or an alkyl or halogen substituent may be present on the benzene ring. If an alkyl group is the substituent on the ring it is desirable that it be selected from those alkyls which have 1-4 carbon atoms such as methyl, ethyl, isopropyl or the like. If a halogen substituent is employed this substituent is most desirably chlorine although the hardening action on the gelatin treated therewith will be efiective if some other halogen substituent such as bromine or fluorine is used.

The following examples illustrate the hardening of gelatin in accordance with our invention:

Example 3 A strip of photographic film having three layers of a gelatin emulsion thereon each sensitive to a different color such as is employed in color photography was immersed for 4 minutes at F. in a solution consisting of 1 gram of 1:3-dihydroxymethylbenzimidazol-Z-one, 15 grams of sodium sulfate, 100 cc. of Water and a sodium borate-boric acid buffer to maintain the solution at a pH of 9. After immersing the film strip for the specified time it was rinsed in water at 100 F. for two minutes and thendeveloped at 100 F. The film strip was subjected to washing with water having a temperature of F..and no change occurred in the emulsion layer. 1

' Example 4 v The procedure of Example 3 .was repeated except that the hardening solution was maintained at a pH of 8 and the film was dried first and then subjected to photographic processing. The resulting film strip was subjected to a washing with Water having a temperature of 160 F. and no change was. found to occur in the emulsion layer.

Example 5 The procedure of Example 4 was repeated but with the addition that after drying the film it was immersed in a solution in Water of resorcinol 04%) and resorcylic aldehyde A very hard film was obtained. In proceeding according to the above examples it was found that when the layers were processed according to Examples 4' and 5 that the resulting emulsion layers had similar photographic properties and a high photographic density was obtained thereby.' It was also noted in these examples that the'speed of the yellow layer was not as great as in the case of those emulsions which had not been subjected to such hardening. However, this lowering of speed could readily be compensated for by increasing the first development time. In many cases the speed reduction ofthe yellow layer is of advantagc such as in those color processes which sufrer from a too rapid deyelopment of the yellow layer. The hardening of the emulsion layer as describedin Example 3 gave good results and was fully equivalent to that obtained with formalin hardening but with the additional advantage, however, t a n t e e pit o m n er q wa in wa r ft t tm n t he f m n n q uq s' e .h e fog in the ye wla s he a inthe sa s 19 th ,.,fi m strip harde i sq id qen i h ,Q iavent q n s oa ingre l s T ellq na s sime re them uetharde ned in accordance with our invention and that hardened with formalin.

Control Test Solution (formalin) Hardening time 1 min. 4 min. sec. 40 sec.

Development time 4 4 4 4 F 0.21 0.21 0. 0.27 2.35 2:20 :2. 18 2. 09 1. 03 0. 95 0. 80 0. 74 8 8 8 8 0. 31 0. 42 0.50 0. 66 2. 35 2. 26 2. 16 1. 96 1. 64 L26 1.17 1.00

s it the ef fn h rf a m nt times the emulsion hardened in accordance with our invention exhibited higher speed and gamma andlower fog than in the case of the forrnalin hardened emulsion. V I c I We have also found that the hardeners referred to above are efiective for hardening gelatin when incorporated in compositions thereof as illustrated by the following examples:

Exainple 6 Three samples of a gelatin-silver halide negative emulsion were taken and in two of those samples hardeners in accordance with our invention were incorporated. The melting point of the emulsion was increased by those additions as shown by the following:

901 melting point of untreated emulsion.

146 melting point of the emulsion to which has been added 4 gram of l:3-di(hydroxymethyl)-beniimida- ZoI-Z-one perliter of emulsion. I c H 207 F. melting point of emulsion containing 1 gram of 1 ;3-di(hydroxymethyl)-benzirnidazol-2-one per liter of emulsion.

Upon coating out of the emulsionandsubjec ting thesame to incubation the hardening thereof is still further increased.

ramble"? fast negative chlorobromide gelatin emiilsion was taken and one sam ple was untreated and two samples Example 8 16 mm. film having thereon a highly sensitive emulsion was immersed in a solution for two minutes having the following composition:

0.3 part of 1:3-di(hydroiiymethyl)-5-methylbenzimidazol-2-one 15 parts of NazSO4 2 parts of NaaCOaHaQ W Water to make parts.

The film after hardening in this solution at lOOf F. for two minutes was washed with water for one minute and then processed in a hydroquinonem'etol type developer for 4, 8 and 16 minutes. The film after processing was examined and was found to bew'e'll hardened for each of the various development times which were used. This hardening compound was also employed to treat photographic film of the color type having three layers of differcnt color sensitivities thereon. It was found that the resulting product had excellent hardness and fog was kept to a minimum.

We claim:

1. A composition of gelatin and a compound having the structural formula crnon -N (2117011 R being a substituent selected from the group consisting of hydrogen, lower alkyl chlorine, bromine and fluorine.

2. A composition of gelatin and l'z3-dihydroxymethylbenzimidazol-2-one.

3. A composition of gelatin and 1:3-dihydroxymethyl- S-rne'thyl benzimidazol-Z-one.

4. A method of hardening a gelatin layer which comprises immersing the layer in an aqueous solution of a compound having the structural formula (IZHaOH -N (ijHaOH R being a substitiient selected from the group consisting of hydrogen, lower alk'yl chlorine, bromine and fluorine. 5. method of hardening a gelatin layer which comprises immersing the layer in an aqueous solution of 1:3- dihydroxymethyI benZimidaZoI-Z one.

6. Arnethod of hardening a gelatin layer which coinprises incorporating in an aqueous gelatin composition 21 small'proporti0n of a compound having the structural formula:

prises incorporating in "anfaque'ous gelatin composition a small proportion of l:3 dihydroirymethyl benzirnidazol- 2-one and coating out'the resulting composition onto 11 support therefor.

hars ness Cited'inthe file of t h ispate'nt UNITED STATES PATENTS

Claims

4. A METHOD OF HARDENING A GELATIN LAYER WHICH COMPRISES IMMERSING THE LAYER IN AN AQUEOUS SOLUTION OF A COMPOUND HAVING THE STRUCTURAL FORMULA