HARDENERS FOR PHOTOGRAPHIC GELATIN
United States Patent 3868257
Compounds represented by the general formula, ##SPC1## (Wherein R is hydrogen or a methyl group and X is a lower alkylene group of 1 to 6 carbon atoms) are effective gelatin hardeners.
US Patent References:
PROCESS FOR THE HARDENING OF GELATINE
Froehlich - July 1969 - 3455892
HARDENERS FOR PHOTOGRAPHIC GELATIN
Burness et al. - January 1970 - 3490911
PROCESS FOR THE HARDENING OF GELATINE
Froehlich - July 1969 - 3455892
HARDENERS FOR PHOTOGRAPHIC GELATIN
Burness et al. - January 1970 - 3490911
Inventors:
Horii, Shoichi (Nagaokakyo, JA)
Yamada, Shoji (Nagaokakyo, JA)
Futaki, Kiyoshi (Nagaokakyo, JA)
Tanaka, Akira (Nagaokakyo, JA)
Sekido, Mamoru (Nagaokakyo, JA)
Miyazawa, Sadayuki (Nagaokakyo, JA)
Yamada, Shoji (Nagaokakyo, JA)
Futaki, Kiyoshi (Nagaokakyo, JA)
Tanaka, Akira (Nagaokakyo, JA)
Sekido, Mamoru (Nagaokakyo, JA)
Miyazawa, Sadayuki (Nagaokakyo, JA)
Application Number:
05/319025
Publication Date:
02/25/1975
Filing Date:
12/27/1972
View Patent Images:
Export Citation:
Assignee:
Mitsubishi Paper Mills, Ltd. (Tokyo, JA)
Primary Class:
Other Classes:
564/154, 530/354, 430/621, 106/154.300
International Classes:
G03C1/30; G03C1/30
Field of Search:
96/111,100 260/117 106/125
Primary Examiner:
Torchin, Norman G.
Assistant Examiner:
Louie Jr., Won H.
Attorney, Agent or Firm:
Cushman, Darby & Cushman
Claims:
What is claimed is
1. A composition of matter comprising gelatin and a hardener of the formula: ##SPC5##
2. A gelatin-silver halide photographic emulsion containing as a hardener therein a compound having the general formula: ##SPC6##
3. A gelatin-silver halide photographic emulsion for use in color photography containing a coupler and as a hardener therein a compound having the general formula: ##SPC7##
4. A composition according to claim 1, wherein the amount of the hardener is 0.1 - 20 percent by weight of gelatin based on the dry weight.
5. An emulsion according to claim 2 wherein the amount of the hardener is 0.1 - 20 percent by weight of gelatin based on the dry weight.
6. An emulsion according to claim 3 wherein the amount of the hardener is 0.1 - 20 percent by weight of gelatin based on the dry weight.
7. A method for hardening a gelatin-silver halide photographic emulsion, characterized in that a hardener having the general formula: ##SPC8## (Wherein R is a member selected from the group consisting of hydrogen and methyl group and X is a lower alkylene group of 1 to 6 carbon atoms) is allowed to be present in contact with the gelatin and hardening the gelatin with said hardener.
1. A composition of matter comprising gelatin and a hardener of the formula: ##SPC5##
2. A gelatin-silver halide photographic emulsion containing as a hardener therein a compound having the general formula: ##SPC6##
3. A gelatin-silver halide photographic emulsion for use in color photography containing a coupler and as a hardener therein a compound having the general formula: ##SPC7##
4. A composition according to claim 1, wherein the amount of the hardener is 0.1 - 20 percent by weight of gelatin based on the dry weight.
5. An emulsion according to claim 2 wherein the amount of the hardener is 0.1 - 20 percent by weight of gelatin based on the dry weight.
6. An emulsion according to claim 3 wherein the amount of the hardener is 0.1 - 20 percent by weight of gelatin based on the dry weight.
7. A method for hardening a gelatin-silver halide photographic emulsion, characterized in that a hardener having the general formula: ##SPC8## (Wherein R is a member selected from the group consisting of hydrogen and methyl group and X is a lower alkylene group of 1 to 6 carbon atoms) is allowed to be present in contact with the gelatin and hardening the gelatin with said hardener.
Description:
The present invention relates to hardeners for photographic gelatin and a method for hardening a gelatin-containing photographic layer.
It has been well known that mechanical strength of photographic layer can be increased and resistances against dissolution, swelling and separation of the layer during photographic processes can be improved by adding a gelatin hardener capable of cross linking physically or chemically with gelatin in preparation of the gelatin-containing photographic layer. A number of compounds have been proposed for gelatin hardeners. Among them, the following compounds have been known to be especially effective; i.e., formalin, mucochloric acid, addition products of formalin, nitrogen-containing heterocyclic six membered ring compounds having two or more of active halogens in the molecule for instance, 2,4-dichrolo-6-β-hydroxyethylamine-1,3,5,-triazine, compounds having active vinyl groups such as divinyl sulfone, divinyl ketone, N,N',N"-triacryloylhexahydro-1,3,5-triazine, compounds containing two or more of aziridine groups or epoxy groups in the molecule and high molecular hardeners such as dialdehyde starch, polyvinyl alcohol and maleic acid half esters of starch, etc. However, these compounds cannot provide satisfactory results in gelatin-containing photographic layer. Even formalin which has been most commonly used has many defects, e.g., the hardening is difficult to control to a desired degree due to the so called post-hardening phenomenon which means gradual hardening caused even at later stage, it tends to result in fog in emulsion and when used in color photographic emulsion, it reacts with color coupler to cause reduction in sensitivity or abnormal color coupling. Regarding other hardeners, some cause coloration of photographic layer and some cause conspicuous changes in hydrogen ion concentration of emulsion with progress of hardening to result in deterioration of photographic properties. Furthermore, some of them have pungent smell to reduce operability in preparation of are harmful for human body. Although, there are many compounds which are photographically not harmful and preferable, but many of them are expensive or require complicated procedures to apply them, e.g., they have to be dissolved in an organic solvent and then dispersed in an emulsion.
It has also been well known that hardeners having active vinyl group can be advantageously used for this purpose. For example, German Pat. No. 872,153 (1949) discloses use of divinyl sulfone, but this compound has strong irritating property and toxicity to human body. Furthermore, German Patent Publication No. 1,100,942 (1961) has proposed aromatic compounds having two or more of vinylsulfonyl groups in the molecule and U.S. Pat. No. 3,490,911 (1970) has proposed compounds having vinylsulfonylethyl groups.
The characteristics of these vinyl sulfone type hardeners are as follows: they have rapid hardening action and the so-called posthardening occurs with difficulty, the so-called over-hardening phenomenon (hardening proceeds to much and photographic emulsion film becomes keratin (becomes brittle) to damage the permeability of processing solution) occurs in low frequency; photographically undesirable actions such as fog, stain or ground, etc., less occur; and the suppression of color development or discoloration caused by reactions with color couplers are not caused. Therefore, the vinyl sulfone type hardeners are excellent in these points, but most of them are too much expensive and moreover some of them require a large amount of organic solvents in their application or the amount of addition must be limited to avoid troubles caused by change in viscosity with lapse of time. Under the circumstances, such vinyl sulfonyl compounds as easily prepared and required no specific procedure for application have been much demanded.
One object of the present invention is to provide effective hardeners for photographic gelatin and for gelatin-containing photographic emulsions. Another object of the present invention is to provide a method for effectively hardening a gelatin-containing photographic layer. Other object of the present invention will appear herein.
The inventors have found that use of the compounds represented by the following general formula can completely overcome the difficulties of the conventional hardeners. ##SPC2##
(Wherein R is hydrogen or methyl group and X is a lower alkylene group of 1 to 6 carbon atoms).
When these compounds are incorporated into gelatin-containing photographic emulsion, such undesired phenomena as photographic deteriorations such as fog, desensitization, coloration of ground, discoloration, change of hydrogen ion concentration of the emulsion, reactions with color couplers, etc., are hardly observed and these hardeners maintain rapid hardening property of the compounds having vinyl sulfonyl groups in common and moreover no so-called post-hardening phenomenon occurs. Therefore, the photographic emulsion layer can be very easily hardened to the desired degree. Furthermore, the change of viscosity of the photographic emulsion during preparation is surprisingly minor as compared with that of the case of other vinyl sulfonyl compounds being used and this is the important characteristic of the compounds used as hardeners of the present invention. These compounds have further characteristics that they are excellent in affinity with water and require no special organic solvent in their application, being different from the other conventional vinyl sulfonyl compounds. Furthermore, the compounds of the present invention are also superior to the conventional vinyl sulfonyl compounds in that they have substantially no bad effect on human body due to gasification and cause less physiological action to the skin.
It seems that most of these excellent properties of the compounds used as hardeners in the present invention which are not possessed by the conventional vinyl sulfonyl compounds are attributable to the action of amide groups in the structure. Because of the strong polarity of said group, the volatility of the compounds is restrained, the affinity to water is increased and the affinity to lipids is lost whereby the toxicity is lowered. Furthermore, since the compounds of the present invention have structure very similar to that of gelatin, there is a little difference in properties between hardened part and unhardened part of the emulsion and the photographic emulsion in which the compounds of the present invention are used shows no great difference in viscosity before and after hardening. The amount in which these hardners will ordinarily be employed will be within the range of 0.1 - 20 percent, more preferably, 2 -5 percent by weight of gelatin based on the dry weight of it. The emulsions hardened by the hardener of the present invention can 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.
Examples of the compounds especially suitable in the present invention are shown below. ##SPC3##
These compounds can be prepared, for example, by dehydrochlorination of the following compound (B). ##SPC4##
(wherein R and X are the same as defined in the compound (A) ).
Besides the above method, the compound (A) will be produced from compounds similar to the compound (B) by known methods of introducing vinyl group.
The β-chloroethyl sulfonyl groups can be introduced as follows:
α, β-Unsaturated fatty acid derivatives and β-chrolo ethane sulfinic acid are reacted to produced compounds having the said group, or hydroxyl groups of β-(β-hydroxylethylthio) fatty acid derivatives produced by reactions of β-mercaptoethanol and α,β-unsaturated fatty acid derivatives are firstly converted to the chrologroups and then its thioether bond is oxidized or firstly β-hydroxyethylthio group is oxidized to convert it into β-hydroxyethyl sulfonyl group and then hydroxyl group is chlorinated into above mentioned group.
Representative Examples of preparation of these compounds are illustrated below.
Preparation 1
β-(β-chloroethylsulfonyl) propionamide
11 g of sodium bisulfite was dissolved in 50 ml of water and the solution was kept at 5° - 10°C and added dropwise thereto with stirring were 16.3 g, of β-chloroethylsulfonyl chloride and a solution of 11 g of sodium hydroxide in 30 ml of water simultaneously over a period of 2 hours. After completion of the addition, the mixture was stirred for 30 minutes and was added thereto 10 g of 49 percent sulfuric acid for 5 minutes. The temperature was decreased to 0° - 5°C and stirring was carried out for 1 hour and thereafter the separated crystal was filtered off. To the filtrate while stirring at 5° - 10°C was added a solution of 7.1 g of acrylamide in 50 ml of water and they were preserved at cold state for 48 hours. The separated crystal was filtered and washed with a small amount of cold water and recrystallized from methanol giving 12 g of colorless crystal having a melting point of 137.5° - 138.5°C.
Preparation 2
N,n'-methylenebis-[β-(β-chloroethylsulfonyl) propionamide]
A mixture of 4 g of α-(α-chloroethylsulfonyl) propionamide obtained in Preparation 1 and 0.6 g of paraformaldehyde was heated in an oil bath at 110°C and 4 drops of concentrated sulfuric acid were added thereto. Thereafter, the bath temperature was gradually raised to 150° - 155°C and reaction was effected for 1.5 hour. After the reaction product was allowed to stand for cooling, water was added thereto and insoluble matter was filtered and recrystallized from water to obtain 2.4 g. of colorless crystalline powder having a melting point of 213.0° - 214.0°C.
Preparation 3
N,N'methylene bis-9β-(β-chloroethylsulfonyl) propionamide) was dispersed in 250 ml of dimethylformamide and added thereto with stirring was 4.44 g. of triethylamine at room temperature. The stirring was continued for 5 hours and then the undissolved matter was filtered off. To the filtrate was added 50 ml of toluene and the mixed solution was concentrated under a reduced pressure into a jelly-like product of considerably high viscosity, to which 30 ml of benzene was added to separate crystal. The crystal was filtered off and was washed with a small amount of ethanol and then was recrystallized from ethanol to obtain 5.5 g. of the desired product having a melting point of 147.0° - 148.0°C.
Elementary Analysis: for C 11 H 18 N 2 O 6 S 2
C H N ______________________________________ Calcd. (%) 39.04 5.36 8.28 Found (%) 39.15 5.47 8.11 ______________________________________
The present invention is further illustrated by the following examples of preferred embodiments thereof.
EXAMPLE 1 To 18 g. of gelatin and no-ammoniacal silver bromoiodide emulsion sulfur sensitized and silver-digested and prepared from 7.5 g. of silver nitrate was added 1 percent aqueous solution of the compound obtained in Preparation 3 in various concentrations and pH was adjusted to 6.5. Each of thus obtained samples was coated on a photographic base paper both faces of which were rendered waterproof by polyethylene coating and which contained no volatile hardening substance such as formalin at a coverage of 1.25 g./m 2 of silver in terms of silver nitrate and 3 g./m 2 of gelatin and thus coated paper was dried.
Some of these samples were stored for 2 days at room temperature and others under acceleration condition of 50°C and 80 % RH for 2 days. Thereafter, each of the samples were exposed through a step wedge, processed for 2 minutes at 20°C in Kodak D-72 (1 : 2) developer, fixed and washed with water. Sensitivity and fog density of these samples were measured. Furthermore, each sample was dipped in 4 percent aqueous solution of Na 2 CO 3 .H 2 O for 3 minutes at 20°C and then a ball point pen having a ball diameter of 1 mm was perpendicularly set on film of the sample emulsion. Then, the sample was horizontally moved at 1 cm/sec. and the minimum load of the ball point pen (referred to as film strength hereinafter) which caused detectable damages on the film of the emulsion was measured. The results are shown in the following Table 1.
Table 1 ____________________________________________________________ ______________ Concent- Samples stored for two Samples stored for two ration of days at room temperature days at 50°C and 80% RH hardeners Relative Fog con- Film Relative Fog Film (g/100g sensiti- centra- strength sensiti- density strength gelatin) vity tion (g) vity (g) ____________________________________________________________ ______________ -- 100 0.02 5 96 0.04 8 1 98 0.02 28 95 0.04 35 3 99 0.02 36 95 0.05 41 5 98 0.02 40 94 0.05 48 ____________________________________________________________ ______________
From the above Table 1, it is clearly recognized that a gelatin-containing photographic emulsion layer which was hardened in a short period of time after coating and showed no over-hardening under acceleration conditions was obtained without causing any undesirable effect on sensitivity and fog density.
Changes of viscosity of thus obtained emulsions with lapse of time were measured with the following results.
Table 2 ______________________________________ Times 1 2 5 8 16 24 hour hours hours hours hours hours ______________________________________ Viscosity of emulsions 6.6 6.7 6.7 6.6 6.8 6.8 (40°C) CPS ______________________________________
It is surprising that according to the method of the present invention, no substantial change in viscosity of emulsion is caused during storage.
EXAMPLE 2
Each of the following hardeners was added to four separate portions of the silver bromoiodide emulsion prepared in the same manner as in Example 1 in a proportion of 2 g. of the hardener per 100 g. of gelatin.
a. The compound obtained in said Preparation 3
b. Formalin
c. Hardener D II S (Trade name of a vinyl sulfon hardener manufactured by Carbic Hoechst Corp.)
d. N,N',N"-triacryloylhexahydro-1,3,5-triazine
Each of the sample emulsions was coated on the same RC base paper as used in Example 1 at a coverage of 1.25 g./m 2 of silver (in terms of silver nitrate) and 3 g./m 2 of gelatin. A sample of each film coating was then dried and cured under conditions of 20°C 58 % RH and 50°C 80 % RH each of them using saturated solution of NaBr. 2H 2 O and Kcl. Film strength of each sample was measured in the same manner as in Example 1 with the following results.
Table 3 ______________________________________ Film strength 20°C 58% RH 50°C 80% RH (g) 2 8 30 3 days days days days ______________________________________ Layer containing hardener (a) 30 32 34 38 (b) 24 36 60 84 (c) 31 32 35 40 (d) 12 20 41 78 ______________________________________
The above results indicate that when the hardener of the present invention was used, the gelatin was hardened to the desired degree in a short period of time after application and post-hardening phenomenon during storage hardly occurred.
According to these results, the rapid hardening action of the hardener of the present invention is comparable to that of the compound (c) and superior to the compound (b) as well as the compound (d).
Compound (a) can be used as a 1 percent aqueous solution, but compound (c) must be added to emulsion as 1 percent DMF solution or 1 percent dioxane solution.
EXAMPLE 3
Example 1 was repeated except that the compound obtained in Preparation 3 was replaced by compound (IV) listed before to obtain the same results as Example 1.
EXAMPLE 4
Example 1 was repeated except that the compound obtained in Preparation 3 was replaced by compound (VII) listed before to obtain the same results as those of Example 1.
EXAMPLE 5
Example 1 was repeated except that the compound obtained in Preparation 3 was replaced by compound (XIII) listed before to obtain the same results as those of Example 1.
It has been well known that mechanical strength of photographic layer can be increased and resistances against dissolution, swelling and separation of the layer during photographic processes can be improved by adding a gelatin hardener capable of cross linking physically or chemically with gelatin in preparation of the gelatin-containing photographic layer. A number of compounds have been proposed for gelatin hardeners. Among them, the following compounds have been known to be especially effective; i.e., formalin, mucochloric acid, addition products of formalin, nitrogen-containing heterocyclic six membered ring compounds having two or more of active halogens in the molecule for instance, 2,4-dichrolo-6-β-hydroxyethylamine-1,3,5,-triazine, compounds having active vinyl groups such as divinyl sulfone, divinyl ketone, N,N',N"-triacryloylhexahydro-1,3,5-triazine, compounds containing two or more of aziridine groups or epoxy groups in the molecule and high molecular hardeners such as dialdehyde starch, polyvinyl alcohol and maleic acid half esters of starch, etc. However, these compounds cannot provide satisfactory results in gelatin-containing photographic layer. Even formalin which has been most commonly used has many defects, e.g., the hardening is difficult to control to a desired degree due to the so called post-hardening phenomenon which means gradual hardening caused even at later stage, it tends to result in fog in emulsion and when used in color photographic emulsion, it reacts with color coupler to cause reduction in sensitivity or abnormal color coupling. Regarding other hardeners, some cause coloration of photographic layer and some cause conspicuous changes in hydrogen ion concentration of emulsion with progress of hardening to result in deterioration of photographic properties. Furthermore, some of them have pungent smell to reduce operability in preparation of are harmful for human body. Although, there are many compounds which are photographically not harmful and preferable, but many of them are expensive or require complicated procedures to apply them, e.g., they have to be dissolved in an organic solvent and then dispersed in an emulsion.
It has also been well known that hardeners having active vinyl group can be advantageously used for this purpose. For example, German Pat. No. 872,153 (1949) discloses use of divinyl sulfone, but this compound has strong irritating property and toxicity to human body. Furthermore, German Patent Publication No. 1,100,942 (1961) has proposed aromatic compounds having two or more of vinylsulfonyl groups in the molecule and U.S. Pat. No. 3,490,911 (1970) has proposed compounds having vinylsulfonylethyl groups.
The characteristics of these vinyl sulfone type hardeners are as follows: they have rapid hardening action and the so-called posthardening occurs with difficulty, the so-called over-hardening phenomenon (hardening proceeds to much and photographic emulsion film becomes keratin (becomes brittle) to damage the permeability of processing solution) occurs in low frequency; photographically undesirable actions such as fog, stain or ground, etc., less occur; and the suppression of color development or discoloration caused by reactions with color couplers are not caused. Therefore, the vinyl sulfone type hardeners are excellent in these points, but most of them are too much expensive and moreover some of them require a large amount of organic solvents in their application or the amount of addition must be limited to avoid troubles caused by change in viscosity with lapse of time. Under the circumstances, such vinyl sulfonyl compounds as easily prepared and required no specific procedure for application have been much demanded.
One object of the present invention is to provide effective hardeners for photographic gelatin and for gelatin-containing photographic emulsions. Another object of the present invention is to provide a method for effectively hardening a gelatin-containing photographic layer. Other object of the present invention will appear herein.
The inventors have found that use of the compounds represented by the following general formula can completely overcome the difficulties of the conventional hardeners. ##SPC2##
(Wherein R is hydrogen or methyl group and X is a lower alkylene group of 1 to 6 carbon atoms).
When these compounds are incorporated into gelatin-containing photographic emulsion, such undesired phenomena as photographic deteriorations such as fog, desensitization, coloration of ground, discoloration, change of hydrogen ion concentration of the emulsion, reactions with color couplers, etc., are hardly observed and these hardeners maintain rapid hardening property of the compounds having vinyl sulfonyl groups in common and moreover no so-called post-hardening phenomenon occurs. Therefore, the photographic emulsion layer can be very easily hardened to the desired degree. Furthermore, the change of viscosity of the photographic emulsion during preparation is surprisingly minor as compared with that of the case of other vinyl sulfonyl compounds being used and this is the important characteristic of the compounds used as hardeners of the present invention. These compounds have further characteristics that they are excellent in affinity with water and require no special organic solvent in their application, being different from the other conventional vinyl sulfonyl compounds. Furthermore, the compounds of the present invention are also superior to the conventional vinyl sulfonyl compounds in that they have substantially no bad effect on human body due to gasification and cause less physiological action to the skin.
It seems that most of these excellent properties of the compounds used as hardeners in the present invention which are not possessed by the conventional vinyl sulfonyl compounds are attributable to the action of amide groups in the structure. Because of the strong polarity of said group, the volatility of the compounds is restrained, the affinity to water is increased and the affinity to lipids is lost whereby the toxicity is lowered. Furthermore, since the compounds of the present invention have structure very similar to that of gelatin, there is a little difference in properties between hardened part and unhardened part of the emulsion and the photographic emulsion in which the compounds of the present invention are used shows no great difference in viscosity before and after hardening. The amount in which these hardners will ordinarily be employed will be within the range of 0.1 - 20 percent, more preferably, 2 -5 percent by weight of gelatin based on the dry weight of it. The emulsions hardened by the hardener of the present invention can 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.
Examples of the compounds especially suitable in the present invention are shown below. ##SPC3##
These compounds can be prepared, for example, by dehydrochlorination of the following compound (B). ##SPC4##
(wherein R and X are the same as defined in the compound (A) ).
Besides the above method, the compound (A) will be produced from compounds similar to the compound (B) by known methods of introducing vinyl group.
The β-chloroethyl sulfonyl groups can be introduced as follows:
α, β-Unsaturated fatty acid derivatives and β-chrolo ethane sulfinic acid are reacted to produced compounds having the said group, or hydroxyl groups of β-(β-hydroxylethylthio) fatty acid derivatives produced by reactions of β-mercaptoethanol and α,β-unsaturated fatty acid derivatives are firstly converted to the chrologroups and then its thioether bond is oxidized or firstly β-hydroxyethylthio group is oxidized to convert it into β-hydroxyethyl sulfonyl group and then hydroxyl group is chlorinated into above mentioned group.
Representative Examples of preparation of these compounds are illustrated below.
Preparation 1
β-(β-chloroethylsulfonyl) propionamide
11 g of sodium bisulfite was dissolved in 50 ml of water and the solution was kept at 5° - 10°C and added dropwise thereto with stirring were 16.3 g, of β-chloroethylsulfonyl chloride and a solution of 11 g of sodium hydroxide in 30 ml of water simultaneously over a period of 2 hours. After completion of the addition, the mixture was stirred for 30 minutes and was added thereto 10 g of 49 percent sulfuric acid for 5 minutes. The temperature was decreased to 0° - 5°C and stirring was carried out for 1 hour and thereafter the separated crystal was filtered off. To the filtrate while stirring at 5° - 10°C was added a solution of 7.1 g of acrylamide in 50 ml of water and they were preserved at cold state for 48 hours. The separated crystal was filtered and washed with a small amount of cold water and recrystallized from methanol giving 12 g of colorless crystal having a melting point of 137.5° - 138.5°C.
Preparation 2
N,n'-methylenebis-[β-(β-chloroethylsulfonyl) propionamide]
A mixture of 4 g of α-(α-chloroethylsulfonyl) propionamide obtained in Preparation 1 and 0.6 g of paraformaldehyde was heated in an oil bath at 110°C and 4 drops of concentrated sulfuric acid were added thereto. Thereafter, the bath temperature was gradually raised to 150° - 155°C and reaction was effected for 1.5 hour. After the reaction product was allowed to stand for cooling, water was added thereto and insoluble matter was filtered and recrystallized from water to obtain 2.4 g. of colorless crystalline powder having a melting point of 213.0° - 214.0°C.
Preparation 3
N,N'methylene bis-9β-(β-chloroethylsulfonyl) propionamide) was dispersed in 250 ml of dimethylformamide and added thereto with stirring was 4.44 g. of triethylamine at room temperature. The stirring was continued for 5 hours and then the undissolved matter was filtered off. To the filtrate was added 50 ml of toluene and the mixed solution was concentrated under a reduced pressure into a jelly-like product of considerably high viscosity, to which 30 ml of benzene was added to separate crystal. The crystal was filtered off and was washed with a small amount of ethanol and then was recrystallized from ethanol to obtain 5.5 g. of the desired product having a melting point of 147.0° - 148.0°C.
Elementary Analysis: for C 11 H 18 N 2 O 6 S 2
C H N ______________________________________ Calcd. (%) 39.04 5.36 8.28 Found (%) 39.15 5.47 8.11 ______________________________________
The present invention is further illustrated by the following examples of preferred embodiments thereof.
EXAMPLE 1 To 18 g. of gelatin and no-ammoniacal silver bromoiodide emulsion sulfur sensitized and silver-digested and prepared from 7.5 g. of silver nitrate was added 1 percent aqueous solution of the compound obtained in Preparation 3 in various concentrations and pH was adjusted to 6.5. Each of thus obtained samples was coated on a photographic base paper both faces of which were rendered waterproof by polyethylene coating and which contained no volatile hardening substance such as formalin at a coverage of 1.25 g./m 2 of silver in terms of silver nitrate and 3 g./m 2 of gelatin and thus coated paper was dried.
Some of these samples were stored for 2 days at room temperature and others under acceleration condition of 50°C and 80 % RH for 2 days. Thereafter, each of the samples were exposed through a step wedge, processed for 2 minutes at 20°C in Kodak D-72 (1 : 2) developer, fixed and washed with water. Sensitivity and fog density of these samples were measured. Furthermore, each sample was dipped in 4 percent aqueous solution of Na 2 CO 3 .H 2 O for 3 minutes at 20°C and then a ball point pen having a ball diameter of 1 mm was perpendicularly set on film of the sample emulsion. Then, the sample was horizontally moved at 1 cm/sec. and the minimum load of the ball point pen (referred to as film strength hereinafter) which caused detectable damages on the film of the emulsion was measured. The results are shown in the following Table 1.
Table 1 ____________________________________________________________ ______________ Concent- Samples stored for two Samples stored for two ration of days at room temperature days at 50°C and 80% RH hardeners Relative Fog con- Film Relative Fog Film (g/100g sensiti- centra- strength sensiti- density strength gelatin) vity tion (g) vity (g) ____________________________________________________________ ______________ -- 100 0.02 5 96 0.04 8 1 98 0.02 28 95 0.04 35 3 99 0.02 36 95 0.05 41 5 98 0.02 40 94 0.05 48 ____________________________________________________________ ______________
From the above Table 1, it is clearly recognized that a gelatin-containing photographic emulsion layer which was hardened in a short period of time after coating and showed no over-hardening under acceleration conditions was obtained without causing any undesirable effect on sensitivity and fog density.
Changes of viscosity of thus obtained emulsions with lapse of time were measured with the following results.
Table 2 ______________________________________ Times 1 2 5 8 16 24 hour hours hours hours hours hours ______________________________________ Viscosity of emulsions 6.6 6.7 6.7 6.6 6.8 6.8 (40°C) CPS ______________________________________
It is surprising that according to the method of the present invention, no substantial change in viscosity of emulsion is caused during storage.
EXAMPLE 2
Each of the following hardeners was added to four separate portions of the silver bromoiodide emulsion prepared in the same manner as in Example 1 in a proportion of 2 g. of the hardener per 100 g. of gelatin.
a. The compound obtained in said Preparation 3
b. Formalin
c. Hardener D II S (Trade name of a vinyl sulfon hardener manufactured by Carbic Hoechst Corp.)
d. N,N',N"-triacryloylhexahydro-1,3,5-triazine
Each of the sample emulsions was coated on the same RC base paper as used in Example 1 at a coverage of 1.25 g./m 2 of silver (in terms of silver nitrate) and 3 g./m 2 of gelatin. A sample of each film coating was then dried and cured under conditions of 20°C 58 % RH and 50°C 80 % RH each of them using saturated solution of NaBr. 2H 2 O and Kcl. Film strength of each sample was measured in the same manner as in Example 1 with the following results.
Table 3 ______________________________________ Film strength 20°C 58% RH 50°C 80% RH (g) 2 8 30 3 days days days days ______________________________________ Layer containing hardener (a) 30 32 34 38 (b) 24 36 60 84 (c) 31 32 35 40 (d) 12 20 41 78 ______________________________________
The above results indicate that when the hardener of the present invention was used, the gelatin was hardened to the desired degree in a short period of time after application and post-hardening phenomenon during storage hardly occurred.
According to these results, the rapid hardening action of the hardener of the present invention is comparable to that of the compound (c) and superior to the compound (b) as well as the compound (d).
Compound (a) can be used as a 1 percent aqueous solution, but compound (c) must be added to emulsion as 1 percent DMF solution or 1 percent dioxane solution.
EXAMPLE 3
Example 1 was repeated except that the compound obtained in Preparation 3 was replaced by compound (IV) listed before to obtain the same results as Example 1.
EXAMPLE 4
Example 1 was repeated except that the compound obtained in Preparation 3 was replaced by compound (VII) listed before to obtain the same results as those of Example 1.
EXAMPLE 5
Example 1 was repeated except that the compound obtained in Preparation 3 was replaced by compound (XIII) listed before to obtain the same results as those of Example 1.