JPH04340539A - Silver halide emulsion - Google Patents

Abstract

PURPOSE:To obtain the silver halide emulsion contg. low-mol.wt. gelatin by allowing the production of the photographic low-mol.wt. gelatin with which the problem of powder splashing is solved and further the high-purity low-mol. wt. gelatin without fresh additives at a low cost. CONSTITUTION:High-mol.wt. gelatin is made into the low-mol.wt. gelatin in a soln. and thereafter, this gel is used for the silver halide emulsion in a soln. state without (drying-solidifying). The soln. contg. the high-mol.wt. gelatin is decomposed by heating at >=85 deg.C under >=1.06atm pressure without substantially adding the additives thereto, by which the high-mol.wt. gelatin is made into the low-mol.wt. gelatin and the high-purity low-mol.wt. gelatin soln. is obtd.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic AgX emulsion containing at least silver halide (hereinafter referred to as AgX) grains and low molecular weight gelatin, and more particularly to a method for preparing the low molecular weight gelatin.

0002

BACKGROUND OF THE INVENTION The use of low molecular weight gelatin in photographic silver halide emulsions is disclosed in, for example, JP-A No. 1-158426.
It is described in No. 2-146033 and No. 2-838. However, there are the following problems when using low molecular weight gelatin. (I) Gelatin aqueous solution whose molecular weight has been reduced by enzymatic decomposition etc. is 2
It does not gel even at low temperatures below 0°C. Therefore, the conventional gelatin manufacturing process (gelatin aqueous solution is gelatinized at low temperature, then processed into dice or noodles and dried) cannot be used. Therefore, an aqueous gelatin solution is applied onto the belt, dried, and solidified by peeling off the solid matter or by spray drying. That is, it is manufactured as a powder. However, a powder with a low specific gravity such as gelatin has the problem of being difficult to handle at a manufacturing site because it easily scatters in the air. (II) A new process for lowering the molecular weight must be added to the conventional gelatin manufacturing process, which increases costs. (III) Adding enzymes or adding acids or alkalis because of the low molecular weight increases the chance of contamination with impurities. Even if the added enzyme is inactivated by heating, it remains as an impurity, and acids and alkalis must be added for neutralization, which increases the salt concentration and increases the drying load. When deionization treatment is performed, the number of processing steps increases, and low molecular weight gelatin itself is also removed as ionic species. Therefore, the yield becomes poor and the cost increases. However, these problems are still unresolved.

0003

[Problems to be Solved by the Invention] The purpose of the present invention is to
The object of the present invention is to solve the aforementioned problems that exist when using low molecular weight gelatin for X emulsions. A further object of the present invention is to provide an AgX emulsion containing low molecular weight gelatin that eliminates the above-mentioned problems.

0004

[Means for Solving the Problems] The objects of the present invention have been achieved by the following items. (1) In a silver halide emulsion containing at least silver halide grains and low molecular weight gelatin, the low molecular weight gelatin undergoes a process of (drying → solidification) after reducing the molecular weight of high molecular weight gelatin in a solution. A silver halide emulsion characterized in that it is added in a solution state. (2) The above-mentioned (1), wherein the molecular weight reduction is achieved by thermal decomposition under a pressure of 1.06 atmospheres or more.
Silver halide emulsion as described. (3) In a silver halide emulsion having at least silver halide grains and low molecular weight gelatin, the low molecular weight gelatin heat-decomposes the high molecular weight gelatin in a solution under pressure of 1.06 atmospheres or more, and then (drying → 1. A silver halide emulsion characterized in that it is obtained through a process of solidification.

[0005] The present invention will be explained in more detail below. Low molecular weight gelatin as used in the present invention refers to gelatin molecules having a molecular weight of 2,000 to 60,000, which accounts for 30% by weight or more of the total gelatin molecules, preferably 50% by weight or more, more preferably 70% by weight or more, and even more preferably 90% by weight or more. Refers to the gelatin that occupies. The low molecular weight gelatin can be added to any step of AgX emulsion production depending on the purpose;
It can be used more preferably for the grain formation process, and can be more preferably used for the nucleation process of tabular AgX grains and untwinned AgX grains. In addition to being used in a reaction vessel for forming AgX particles, it can also be used by being added to a silver salt solution or a halogen salt solution. In particular, AgX emulsions in which parallel double-twinned tabular grains account for 90% or more of the projected area ratio, and AgX emulsions in which untwinned grains account for 95% or more of the projected area ratio.
It can be preferably used in the nucleation step of the X emulsion. For details of these, see JP-A-2-838 and JP-A-2-14.
The descriptions in No. 6033 and No. 1-158426 can be referred to. On the other hand, high molecular weight gelatin refers to conventional gelatin, preferably photographic gelatin, in which gelatin molecules with a molecular weight of 70,000 or more account for 70% by weight or more, further 85% by weight or more of the total gelatin molecules.

(A) Problems in Using Low Molecular Weight Gelatin Problems (I) and (II) mentioned in the section of the prior art have been solved by the method (1) of the present invention. That is, an aqueous solution of high-molecular-weight gelatin is prepared, and after its molecular weight is lowered by the following molecular weight-lowering treatment, it is used in a solution state for an AgX emulsion. In this case, the drying process (drying → solidification process) of low molecular weight gelatin is eliminated, and the problem of gelatin powder scattering is also eliminated. In this case, the following method can be used as a treatment for lowering the molecular weight.

[0007] ■ A method in which an enzyme is added to an aqueous solution of high molecular weight gelatin, enzymatically decomposed, and then heated to deactivate the enzyme. As the enzyme, known proteolytic enzymes can be used. For details on types of enzymes, enzymatic decomposition conditions, and heat inactivation, see Reedley, Translated by Kiyoshi Maruyama, Introduction to Enzyme Chemistry, Maruzen (1981), Edited by the Japanese Biochemical Society, Biochemistry Data Book I, Tokyo Kagaku Doujin ( (1979), R. J.
Edited by Cox, Photographic Gelati
n (photographic gelatin) II, Academic Pres.
s. London (1976), edited by Kunihiko Shimonaka, World Encyclopedia Dictionary, "Enzyme section," Heibonsha (1970) can be referred to. A specific example is pronase,
Examples include trypsin, papain, phytin, renin, chymotrypsin, and the like. When the temperature is raised to 60°C or higher, the protein portion is denatured and inactivated. Usually 10-5
Enzymatic decomposition at 0°C, preferably 20-40°C, and 60°C
As mentioned above, the enzyme is preferably inactivated at 70 to 85°C. Usually, the specific decomposition point of gelatin molecules differs depending on the type of enzyme used, but in the case of AgX emulsions, the difference is not a big problem because the main effect is low molecular weight. Since enzymes decompose only specific parts, they have the advantage that even after complete decomposition, there are few inactive components with a molecular weight of 2000 or less.

[0008] ■ Add an acid to an aqueous solution of high molecular weight gelatin to make it pH 4 or less, preferably pH 3 to 1, lower the molecular weight by an acid or hydrolysis method, or add an alkali,
A method of adjusting the pH to 10 or more, preferably pH 11 to pH 13, and lowering the molecular weight by an alkaline hydrolysis method. After reducing the molecular weight, the pH is adjusted to the desired pH by adding an alkali or acid. Since the pH of deionized alkali-treated gelatin is in the range of 4.7 to 5.1, it is usually preferable to add an acid because the purpose can be achieved with a smaller amount of addition. The acid to be added is preferably a non-halogen acid. For example, nitric acid, sulfuric acid, phosphoric acid, acetic acid, etc., with nitric acid being more preferred. When using a halogen acid, it is necessary to consider the concentration of halogen ions remaining in the solution. This is because when AgNO3 is added, AgX is generated.

■ Thermal decomposition method. When the temperature of the high molecular weight gelatin aqueous solution is raised, the rate of thermal decomposition becomes faster and the molecular weight can be reduced in a short time. In this case, the heating temperature is preferably 85°C or higher, and 1
00 to 250°C is more preferable, and even more preferably 120 to 250°C. The pressure during heating is preferably 1.0 atm or higher, more preferably 1.06 atm or higher, even more preferably 1.2 to 10 atm, and most preferably 1.5 to 6 atm. Pressurizing prevents water from boiling and evaporating, and keeps the temperature at 100℃.
It is possible to increase the value above, which is more preferable. In addition, regarding the boiling point of the gelatin solution, the following description can be used as a guide. The boiling point of a solution containing a nonvolatile substance is higher than that of a pure solvent. This is called boiling point rise. In dilute solution,
The following relationship exists between ΔT, which is the increase in the boiling point, and m, the molar concentration of the nonvolatile substance. △T=Km, in aqueous solution K=0.
52. Also, the boiling point of water under pressure PmmHg (
°C) is approximated by the following formula. Furthermore, by setting the temperature (boiling point), the vapor pressure P at that time can be determined. Boiling point = 100 +0.0367 (P-760) -0
．． 000023(P-760)2 (1)

[
[0010] This thermal decomposition method can also be used in combination with the method (2) above. That is, when used in combination, the molecular weight can be lowered in a shorter time. However, this method (2) has the advantage that the molecular weight can be reduced within a short time even under near-neutral pH conditions (ie, pH 4 to 10). Therefore, the molecular weight can be reduced within a short time even without adding any acid or alkali. In the case of deionized alkali-treated gelatin, it is preferable to lower the molecular weight at pH 4.7 to 5.1. This is because the molecular weight can be lowered while suppressing impurity contamination as much as possible. Note that any known autoclave device can be used as a reaction device for heating under pressure. Cooking pressure cookers and pressure cookers are also types of autoclave equipment. For details on the types and usage of the autoclave equipment, see Gutterman and Wieland, translated by Urushibara et al., Organic Chemistry Experiment Book, Chapter A, Kyoritsu Shuppan (1).
966), edited by Kunihiko Shimonaka, World Encyclopedia, section on "autoclave", Heibonsha (1970), edited by the Chemical Society of Japan,
New Experimental Chemistry Course 1, Basic Operations II, Chapter 5, Maruzen (19
You can refer to the description in 1975).

■ Oxidative decomposition method. Other methods for reducing the molecular weight include an oxidative decomposition method (for example, adding H2O2 or O2 and heating at pH 5 or less to decompose the bonds of gelatin molecules by oxidation). Regarding this, European Patent No. 035556
8A2 and JP-A-62-157024, and regarding the oxidizing agent, reference may be made to the description in European Patent No. 0166347B1.

[0012] Ultrasonic irradiation decomposition method. Moreover, cutting can also be performed by ultrasonic irradiation. Regarding this, see Noriichi Ito et al., Journal of the Photographic Society of Japan, Vol. 51, 490.
-494 (1988) can be referred to.

[0013] It is also possible to reduce the molecular weight by using two or more of the above methods in combination. The molecular weight may be reduced in advance under various conditions, the relationship between the conditions and the weight average molecular weight determined, and the rest may be manufactured using that relationship. The weight average molecular weight distribution of gelatin molecules in a gelatin solution can be determined by gel filtration chromatography. This is because the difference in molecular weight is determined by the difference in filtration rate, and this is measured by the spectral absorption amount (which is proportional to the amount of substance). In addition, it can also be determined by developing it on an electrophoretic chromatography developing membrane and measuring its spectral absorption. For details on these, please refer to the descriptions in Christian, translated by Masahiko Tsuchiya, Analytical Chemistry II, Chapter 5, Maruzen (1989), edited by Hiroshi Terada, Electrophoresis, Hirokawa Shoten (1989). can.

[0014] Although there is no particular restriction on the gelatin concentration at the time of reducing the molecular weight, it is more preferable to use a high concentration because a large amount of low molecular weight gelatin can be obtained in a small container. Therefore, in each case it is preferred to increase the concentration within an acceptable range. The concentration is usually preferably 3% by weight or more, and 7% by weight or more.
-60 weight% is more preferable, and 10-40 weight% is still more preferable. Among the methods (1) to (2) above, methods (1) to (2) are more preferred, and (2) is even more preferred.

After the molecular weight has been reduced in this manner, the gelatin solution is transferred to a storage tank or directly to a reaction vessel for AgX emulsion. Normally, the bottom stopper of the low molecular weight container is opened and the liquid is transferred using natural gravity, but the liquid can also be transferred using a liquid transfer pump. Regarding the transfer of the solution, reference may be made to the description in Japanese Patent Application No. 2-266615. After the liquid transfer, the container can be washed with a small amount of hot water (usually water at 25°C or higher, preferably 35 to 75°C), and the washing liquid can also be transferred and used. After cleaning the container,
You can also throw away the cleaning solution. After the washing, the next preparation of the low molecular weight gelatin solution can be started. Although the washing step can be carried out without it, it is preferable to include it since the molecular weight distribution can be narrowed. In a more preferred embodiment, the molecular weight reducing device is installed near the AgX emulsion manufacturing device, and after the molecular weight is reduced, preferably within 5 hours,
More preferably, it is used by directly transferring the liquid to an AgX emulsion manufacturing apparatus within 3 hours.

The low molecular weight gelatin solution thus produced and stored in a storage tank can be used in the following manner. 1) Ag
Used for producing X emulsion. Usually, it may be used within 2 to 3 days, preferably within 1 day, and more preferably within 8 hours after production. 2) Add preservatives such as phenol or phenol derivatives and use within the period before spoilage. Regarding preservatives, see JP-A Nos. 1-253727 and 2-287535.
No., JP-A-59-226343, JP-A No. 59-22634
Reference may be made to the descriptions in No. 4 and No. 59-228247. 3) Concentrate by vacuum dehydration and store. In the case of a low molecular weight gelatin solution, it is easy to handle because it has a low viscosity even if the concentration is high. The concentration is usually preferably 5 to 75% by weight, more preferably 10 to 60% by weight, and 15 to 50% by weight.
is even more preferable. 2) and 3) can also be used together. However, method 1) is the most preferred because it requires fewer steps and has no additives, resulting in higher purity. (B) High-purity low-molecular-weight gelatin In order to produce high-purity low-molecular-weight gelatin, it is necessary to lower the molecular weight without adding substantially anything to a high-molecular gelatin solution. Most preferably, the gelatin may be reduced in molecular weight without adding anything to a solution containing deionized, highly pure, alkali-treated high molecular weight gelatin. For this purpose, the above-mentioned thermal decomposition method under pressure is used. That is, the heating temperature is preferably 85°C or higher, more preferably 100 to 250°C, and even more preferably 120 to 250°C. The pressure during heating is preferably 1.06 atm or higher, more preferably 1.2 to 10 atm, and even more preferably 1.5 to 6 atm. For other matters, the description in section (A) above can be referred to. Although the high-purity low-molecular-weight gelatin can be used in the conventional manner (drying→solidification), it is more preferable to use it as a solution as described in section (A) above. Here, "substantially" means that the amount of acid/alkali added is within (the pH value of the gelatin-only solution ±1). Even if enzymes are added, they are inactivated by heating and are ineffective, so they are not added.

(C) Others In addition, the low molecular weight gelatin can be added to the AgX emulsion before coating in order to improve the film quality of the AgX photographic material. The content of low molecular weight gelatin in the AgX photographic emulsion containing low molecular weight gelatin of the present invention is usually 50% or less, often 30 to 0.1% by weight, and more often 15 to 0.3% by weight. For the AgX emulsion of the present invention, any combination of known techniques and known compounds described in the following documents can be used.

Research Disclosure (Resea)
rch Disclosure), Volume 176 (Item 17643) (December, 1978), Volume 184 (Item 18431) (August, 1979), Volume 216 (Item 21728, May, 1982), Volume 307
Volume (Item 307105, November, 1989), E. J. Birr, Stabilization of Photographic Silver Halide Emulsions.
of Photographic Silver H
Focal Press, London (1974)
The Theory of the Photo Process (ed.), T.H. James (ed.), The Theory of the Phot
Graphic Process), 4th edition, Macmillan, New York (1977
Year),

Written by P. Glafkides
, Chemistry and Physics of Photography
que Photographiques), 5th edition,
Edition da Risine Novel
'n de I'Usine Nouvelle, Paris,
Part 3 (1987), 2nd edition, Paul Montel, Paris (1957), V.L. Zelikman et al.
ikman et al. ), Making and Coating Photo
graphic emulsion), Focal P
ress1964), Hollister (K.R.Holl
ister) Journal of Imaging
Science (Journal of Imaging)
science), Volume 31, P. 148-156 (19
1987), Maskasky (J.E. Maskasky)
, Volume 30, P. 247-254 (1986), Volume 32, 160-177 (1988),

Frieser et al., eds., Fundamentals of the Silver Halide Photographic Process (Die Grundlagen Der Pho
tographischen Prozesse Mi
t Silverhalogeniden), Akademische Verlaggesellschaft (Akadem
ische Verlaggesellschaft)
, Frankfurt (1968). JCIA Monthly Report 198
4th year, December issue, P. 18-27, Journal of the Photographic Society of Japan, 4
9, 7-12 (1986), 52, 144-1
66 (1989), JP-A-59-113926-11
3928, No. 59-90841, No. 58-11193
6, 62-99751, 60-143331, 6
0-143332, 61-14630, 62-62
51, 63-220238, 63-151618,
63-281149, 59-133542, 59
-45438, 62-269958, 63-305
343, 59-142539, 62-253159

[0021] 62-220238, 62-2665
No. 38, Patent Application No. 62-263319, No. 62-2191
73, JP 1-131541, JP 2-838, JP 2-
34, 2-146033, 2-28638, 1-
297649, No. 1-183417, No. 2-1276
35, U. S. 4,636,461, 4,707,4
36, 3,761,276, 4,269,927

[
The silver halide emulsion of the present invention can be used in black and white silver halide photographic light-sensitive materials [for example, X-ray light-sensitive materials, printing light-sensitive materials,
Photographic paper, negative film, microfilm, direct positive photosensitive material, ultrafine particle dry plate photosensitive material (for LSI photomasks, shadow use, LCD masks)] color photographic photosensitive materials (e.g. negative film, photographic paper, reversal film, direct photosensitive material) It can be used for positive color sensitive materials, silver dye bleaching photography, etc.). Furthermore, it can be used in light-sensitive materials for diffusion transfer (for example, color diffusion transfer elements, silver salt diffusion transfer elements), heat-developable light-sensitive materials (black and white, color), high-density digital recording light-sensitive materials, light-sensitive materials for holography, and the like.

[0023]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples. Example 1 One liter of an aqueous gelatin solution (containing 200 g of deionized alkali-treated gelatin) was placed in an autoclave container having a capacity of 2 liters, the lid was placed, and the container was placed in a heating mantle. While shaking the device (container + mantle heater), heat the mantle heater for about 1 hour for 3 hours.
Heated to 30°C. The vapor pressure of water at 130°C is 2.
Since it is 7 kg/cm2, the internal atmospheric pressure is also close to that value. After cooling the container, the lid was opened and the gelatin solution was taken out. When a part of the gelatin solution was subjected to gel filtration chromatography, the weight average molecular weight was approximately 2.
It was 10,000.

Next, 350 ml of the low molecular weight gelatin solution, 45 g of KBr, and H2O were placed in a reaction vessel for producing an AgX emulsion.
9,650 ml of AgNO3 aqueous solution (32 g of AgNO in 100 ml) was added while stirring.
3) and KBr aqueous solution (23.2 in 100 ml)
g of KBr and 4.3 ml of the low molecular weight gelatin solution) were mixed simultaneously at 250 ml/min to 275 ml each.
was added. After 1 minute, add an aqueous gelatin solution (320 g of deionized alkali-treated gelatin, 1400 ml of H2O, p
After adding H6.5) and stirring for 2 minutes, the temperature was raised to 75°C. After the first ripening for 15 minutes, 63 ml of Ag-2 aqueous solution (100 ml contains 315 g of AgNO)
292 ml/min was added. Next, NH4 NO3 (
74 ml of NH3 (25 wt%) aqueous solution and 74 ml of NH3 (25 wt%) aqueous solution were added, and the mixture was further aged for 20 minutes. Next H
An aqueous NO3 (3N) solution was added to adjust the pH to 5.5. .

Next, a KBr-2 aqueous solution (100 m
(containing 15 g of KBr) was added, and Ag-
2 aqueous solution (contains 20g of AgNO3 in 100ml)
and KBr-2 aqueous solution at a silver potential of -30 mV.
D. J. Added. That is, it was added for 5 minutes at 160 ml/min, and then added for 20 minutes at an initial rate of 160 ml/min and a linear flow rate acceleration of 6 ml/min. After stirring for 3 minutes, a flocculation and sedimentation agent was added, the temperature was lowered to 30°C, and the mixture was sedimented and washed with water. Next, add gelatin aqueous solution and redisperse at 40°C, pH 6.4, p
It was adjusted to Br2.6. Observation of a transmission electron micrograph of a replica of the obtained emulsion grains revealed that the average projected grain size was 1.
．． Tabular grains with a diameter of 2 μm and an average aspect ratio of 7.5 are
It occupied more than 99% of the projected area.

Next, the temperature of the emulsion was raised to 55°C, and a sodium thiosulfate aqueous solution was added at 1.6 x 10-5 mol/mol A.
Then, gold-thiocyanate complex (mixture of chloroauric acid and sodium thiocyanate in a molar ratio of 1:50) was added in an amount of 1.2 x 10-5 mol/mol AgX.
Aged for 0 minutes. Lower the temperature to 40℃ and apply antifoggant [
TAI (4-hydroxy-6-methyl-1
,3,3a,7-tetraazaindene] to 1
Only 0-3 mol/mol AgX was added, and after 10 minutes, a coating aid (sodium dodecylbenzenesulfonate) and thickener [sodium poly(4-sulfostyrene) salt] were added, and together with the gelatin protective layer, cellulose triacetate was transparent. The base was coated with 1.5 g/m2 of silver and allowed to dry. The sample was passed through an optical wedge and exposed to blue light for 10-2 seconds.
After exposure, the film was developed for 4 minutes at 20°C using a developing solution "Hyrendol" manufactured by Fuji Film Co., Ltd., and exhibited excellent photographic properties. The low molecular weight gelatin content of the AgX emulsion before coating was approximately 3.7%, taking into account the amount of gelatin that flows out when the emulsion is washed with water.

[0027]

Effect of the invention (1) In the present invention, after reducing the molecular weight of high molecular weight gelatin in a solution, (drying → solidification)
Since it is used as a solution without any drying, the drying process of the low molecular weight gelatin solution can be omitted. Therefore, costs can be reduced. (2) Since low molecular weight gelatin does not take the form of a dry powder, there is no problem of conventional powder scattering. (3) When the molecular weight is reduced by thermal decomposition under pressure, high purity low molecular weight gelatin can be obtained because the molecular weight is reduced without additives.

Claims (3)

[Claims] Claim 1: In a silver halide emulsion containing at least silver halide grains and low molecular weight gelatin, the low molecular weight gelatin is produced by a step (drying → solidification) after reducing the molecular weight of high molecular weight gelatin in a solution. A silver halide emulsion characterized in that it is added in a solution state without undergoing any process. 2. The silver halide emulsion according to claim 1, wherein the molecular weight reduction is achieved by thermal decomposition under a pressure of 1.06 atmospheres or more. 3. A silver halide emulsion comprising at least silver halide grains and low molecular weight gelatin, wherein the low molecular weight gelatin contains the high molecular weight gelatin in a solution containing 1.06
After thermal decomposition under pressure higher than atmospheric pressure (drying → solidification)
A silver halide emulsion characterized in that it is obtained by passing through the steps of.