JPS62218959A - Production of photographic silver halide emulsion - Google Patents

Abstract

PURPOSE:To produce a photographic silver halide emulsion contg. flat platy silver chloride-based particles in a simpler manner with higher reproducibility by precipitating silver chloride-based silver halide particles in the presence of thiourea or a thiourea deriv. CONSTITUTION:A halide soln. is mixed with a silver salt soln. in the presence of thiourea or a thiourea deriv. to produce a silver halide emulsion contg. flat platy silver halide particles having >=5:1 average aspect ratio by at least 60% of the total projection area of all the particles in the emulsion. In the flat platy silver halide particles, >=about 50% of the silver is present as chloride and the particles have parallel {111} principal crystal faces confronting each other. The preferred average aspect ratio of the particles is >=10:1, and >=15:1 average aspect ratio can be obtd. under optimum growth conditions. The thickness of the particles is <=0.5mum, typically <=0.05mum.

Description

Detailed Description of the Invention (5) Industrial Application Field The present invention is useful in the field of photographic materials, particularly 5:
The present invention relates to a method for producing a silver halide emulsion containing tabular grains consisting entirely of silver chloride and having an average aspect ratio greater than 1.

CB) Prior Art and its Problems Silver chloride based /% silver halide photographic emulsions are known and offer particular advantages. For example, silver chloride is more soluble than other photographically useful silver halides so that development and fixing can be accomplished within a short period of time. Silver chloride-based silver iodochloride emulsions have high contrast as photolithographic materials) 1-
It has particular utility in applications that require rapid photographic processing to obtain the desired results.

Various grain shapes have been observed in silver halide photographic emulsions. With regard to the pre-A crystalline form of the silver halide grains, factors such as the presence of grain growth modifiers, the choice of double-jet or single-jet precipitation, or the presence of halides during grain precipitation can be substantially affected. This is thought to have an impact.

It is well known among those skilled in the art that silver chloride crystals tend to form cubic grains having (100) crystal faces. In the overwhelming majority of photographic emulsions, when chlorinated urine is present,
It shows the shape of a cube. Although with some difficulty, it has been possible to modify the crystalline properties of silver chloride to some extent. C1aes et al., “Crystal Custom Modification of Agct Due to Impurities Determining Solvation (Crys et al.
tal Habit Modification of
AgCtby Impurities Dete-rm
ing the 5evolution) J, The Journal of Photographic Science, 21
(110) and (111) by the use of grain growth modifiers of Cypress, Vol., pp. 39-50, 1973.
The formation of silver chloride crystals with gold faces is taught. Also, wyrsch is r (111), (110)
and (ioo) sulfur sensitization of single-sized silver chloride emulsions with crystalline properties.
on of Monosized 5ilver Chl
oride Emulsions with (111)
, (110) and (100) Crystal H
triple-precipitated St chloride in the presence of ammonia and a small amount of divalent cadmium ions discloses a jet precipitation process, but p in the presence of cadmium ions
Ag and pH measurements.

- depending on the rule, rhombic dodecahedron (110), octahedron (11
1), and cubic (ioo) crystalline characteristics occurred.

Although tabular silver halide grains have been extensively studied, these are mostly limited to silver bromide or silver iodide. As used herein, tabular grains refer to grains having two parallel or essentially parallel crystal faces that are substantially larger than any other single crystal face of the grain. The aspect ratio (ie, the ratio of diameter to thickness δ) of the tabular grains is substantially greater than 1:1. High aspect ratio tabular silver bromide emulsions are available from Cugnac and Chat.
eau), [Evolution of the Morpho of Silver Bromide Crystals During Physical Ripening]
logic of 5ilver BromideCry
stals During Physical Rip
ening) J, 3science et Industry
ries Photographiques, Vo13
3, O2 (1962), PP, 121-125.

A study on tabular silver iodobromide grains is provided by Duff-ry
(Duffin), “Chemistry of Photographic Emulsions (Photog)
rapicEmulsion Chemistry May, Focal Press, 1966, PP66-72 and Trivelli and Smith.
), “The Effect of Silver Iodide on the Structure of the Silver Bromoiodide Precipitation Series”
ide Upon the 5structure of
Silver Bromo-Iodide Preci
pitation 5eries) J, ThePhoto
graphic Journal, vol, LX
XX, 1940, PP2B5-288. As described above, the halogen composition of the tabular silver halide grains is preferably silver bromide and silver bromoiodide, and they can be produced by combining methods known in the art. For example, in an atmosphere with a pBr of 1.5 or less, silver bromide tabular grains are present at a weight of 50 or more to form 1-mu crystals, and the insect and halogen solutions are added at the same time while keeping the pBr below 1.5. The grain size, grain shape (diameter/M ratio, or aspect ratio), and grain size can be obtained by growing 1-crystals with The distribution and growth rate of particles can be controlled. Silver halide layer agents that are often used include:
Power; able to do it.

There are few reports of tabular grains made of silver chloride. JP-A-58-108525 discloses that in the presence of ammonia, chloride and! '' discloses a method for preparing radiation-sensitive silver halide photographic emulsions containing tabular cyclized silver grains by simultaneously introducing a salt solution by a double jet method. Further, JP-A-58-111937 describes a method for producing high aspect ratio silver chloride tabular grains by using a veptizer containing a thioether bond. However, the method using ammonia can only be used at a relatively high pH, and the method using a thioether bond-containing peptizer has a significant 1σ1] that requires keeping the T'H-4 low and the need to maintain the pH. 2g per
This method has some problems, such as requiring three meals a day. In order to obtain a more favorable result 1, there were constraints on raw materials such as the inability to use inexpensive sodium chloride as the chloride.

Furthermore, silver bromochloride tabular grains containing mainly bromide are disclosed in JP-A-58-111936; There were constraints such as having to use high concentrations.

In view of the above, it has been strongly desired to develop a method for producing a silver halide photographic emulsion containing tabular grains consisting entirely of silver chloride, which is simpler and has better reproducibility.

Those skilled in the art will appreciate that thiourea or its derivatives can be used as silver halide solvents! -1 is publicly known. For example, JP-A No. 53-82408, No. 55-77737, No. 5
6-57034, 58-211753, etc.

It is added during or after the precipitation of silver halide grains, during or after physical ripening, and is used to increase or reduce the total grain size of silver halide grains. However, no method has yet been disclosed in which thiourea or a derivative thereof casts some kind of shadow during grain nucleation of silver chloride grains, thereby making the grains tabular in shape.

(e) Purpose of the Invention The present inventors have worked diligently to develop a method for producing silver halide photographic emulsions containing grains mainly composed of tabular silver chloride, which is simple and has better reproducibility. As a result, it was found that a method of total precipitation of silver halide, which consists entirely of silver chloride, in the presence of thiourea and thiourea derivatives was suitable for the purpose.

Based on this knowledge, the present invention was completed.

An object of the present invention is to provide a novel method for producing a silver halide photographic emulsion containing a dispersion medium and tabular silver chloride living grains.

CD) The structure of the invention, that is, the present invention, is to mix a halide and a silver salt solution in the presence of thiourea or a thiourea derivative, and to obtain a solution in which about 50 mole or more of chloride is chloride to silver, and the ratio is greater than 5:1. When producing a silver halide emulsion in which tabular grains having a large average aspect ratio and having opposing parallel (111) main crystal faces account for at least 60% of the total grain projected area, a halogen characterized by: This is a method for producing a silver oxide photographic emulsion.

As used herein, "aspect ratio" means the ratio of a particle's diameter to its thickness. The "diameter" of a grain is defined as the diameter of a circle having an area equal to the projected area of the grain when observed under an emulsion full-optical or electron microscope. The term "total grain projected area" means the sum of the projected areas of individual grains when the emulsion is emulsified.

The tabular grains contained in the emulsion produced according to the present invention are 5
:1, preferably at least 10:1', although aspect ratios of 15:1 or more are possible under moderate growth conditions. The thickness of particles with preferred aspect ratios is less than 0.5 μm, typically at least 0.05 μm. Further, in a preferred embodiment, it is also possible to make the number smaller.

Of the silver halide grains contained in the emulsions prepared according to the invention, at least 60%, and more preferably 80%, based on the total projected area of said grains, are present in the form of tabular grains. The tabular grains typically have a triangular or hexagonal shape and have two opposing parallel [1117 major crystal faces. These tabular grains have the same morphology as the tabular grains of silver bromoiodide and silver bromoiodide. Defined by crystal plane. This fact can be easily ascertained by methods well known to our confectioners, namely, X-ray diffraction measurement of emulsion grains and crystallography.

The tabular grains of the chloride living body according to the present invention can be produced using the known Chondral method or double jet method. The silver chloride-based tabular grains defined herein are not formed in the absence of thiourea or thiourea derivatives. This thiourea or thiourea '44 is added with a halogen g solution and a silver salt solution in an amount of 10-5 to 1o-1 mol, more preferably 10 to 10 mol, per 1 mol of silver halide. It is safe to have it present in the reaction vessel at the moment of mixing and at the beginning of mixing. That is, it is an essential condition that the minimum alpha degree of thiourea or thiourea derivative necessary for tabular grain formation is present in the reaction vessel during the initial nucleation of the grains and during the subsequent growth of the grains. In addition, thiourea or thiourea derivatives can be present in the reaction vessel at least at the above-mentioned minimum degree throughout the mixing of the halogen bath and the salt solution, but it is preferable that the concentration remains constant. preferable.

Thiourea or a thiourea derivative may be introduced into the reaction vessel in accordance with a commonly used method of adding a ripening agent. That is, the required amount of thiourea or thiourea derivative may be added into the reaction vessel from the beginning, or the thiourea or thiourea derivative may be added to the reaction vessel in the same or different amount as the silver salt or halogen bath solution. It can be contained through the jet. However, the concentration necessary for producing tabular grains must be satisfied in the reaction vessel at the moment of mixing the halogen solution and the silver salt solution and at the beginning of the mixing.

Thiourea or thiourea derivatives used in the invention are disclosed in, for example, JP-A-53-82408 and JP-A-56-57.
034, 58-211753, etc. can be used. Specific examples are listed below, but the thiourea fat is not limited thereto. In addition, the total number of carbonaceous ridges of the thiourocorticoid is preferably 30 or less, more preferably 20 or less.

(11)s(13)S C84 The pAg in the reaction vessel is maintained in the range of 7-10 during particle nucleation and subsequent particle growth.

More preferably, it is maintained within the range of 7.5 to 9.0.

An aqueous solution of a water-soluble silver salt and a water bath solution of a water-soluble halide are simultaneously added into the reaction vessel by a double jet method. There are no restrictions. Examples of water bathable silver salts include silver nitrate and silver perchlorate, and as water-soluble halides, all water-soluble chlorides such as sodium chloride, potassium chloride, and ammonium chloride can be used.

Furthermore, if necessary, a water-bath bromide or a water-bath iodide commonly used by those skilled in the art may be mixed with the chloride.
The halogen composition of the halide solution is about 50 moles or more chloride, preferably at least 70 moles chloride.

The composition of the halide storage solution is directly reflected in the composition of the tabular grains produced. For example, when producing all tabular grains with a silver chloride:silver bromide molar ratio of 8=2, the molar ratio of chloride ions:accumulative ions in the norogenide bath solution used should be 8=2. There is no need to make the base ion much more sensitive to the co-system ion. The halogen composition of the emulsion base can be individually ascertained by methods known to those skilled in the art, for example by X-ray diffraction measurements.

Gelatin is used as a dispersion medium for silver halide grains.

4 gelatin vj, colloidal albumin, casein,
Cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, g-ten, sodium alginate,
Starch derivatives, etc., synthetic hydrophilic colloids, such as polyvinyl alcohol, polyN-vinylpyrrolidone, polyacrylic copolymers, polyacrylamide, or derivatives thereof, etc., and these dispersion media may be used as necessary. Compatible mixtures of two or more of the following can be used, such as a co-merger of acrylamide, acuvinyl limic acid and mefumadazole.

Furthermore, pA during nucleation and growth of tabular grains
Conditions other than g, such as p)i+1 in the reaction vessel and 1M degrees, are not particularly limited, but the pH value is preferably about 2 to about 9, particularly 5 to 8.

The temperature is suitably in the range of about 30°C to about 90°C, and particularly preferably in the range of 35°C to 80°C.

Although the pH value and temperature may be changed during nucleation and growth of tabular grains, keeping them at constant values gives more favorable results.

After mixing the halogen solution and the silver salt solution, the emulsion is desalted by a method known to those skilled in the art, and can be chemically and spectral sensitized if necessary.

Hereinafter, in order to clarify the effects of non-invention, examples will be given and specifically explained, but non-invention is not limited to these.

Old) Examples The present invention will be further explained according to the following examples. On each side, the contents in the reaction vessel were vigorously stirred during the introduction of the silver and halide salts.

Unless otherwise specified, all solutions are water bog solutions and rMJ
indicates mole gold once.

(Example 1) (Comparison) 12 each of 2M solution of AgNO3 and 2M bath solution of NaCl
0 Biao was added to a 400rnt 8% gelatin bath solution for 40 minutes using a metering bong so that the pAg was maintained at 8.0. During this time, the temperature was maintained at 50° C. and the pR was maintained at 7.0. When the produced particles were observed using a one-child imitation technique, the shape of the particles was as follows: (Due to the large excess of rogen, some of the corners of the particles were somewhat rounded). pAg'
The results were the same even when the i8.0 or higher conditions were used, and tabular grains were not produced using only silver salt solution and chloride solution. (Example 2) 8% gelatin solution was placed in a 1400 dk reaction vessel, A g N Os solution and 2 M NaCtrlWW (0
,005M of exemplified compound (3)) and 3 g/
Add and mix at min for 40 minutes. During mixing, the pAg in the reaction vessel was maintained at 8.0. Temperature: 50°C, p)i: 6.
It was kept at 4. The tabular grain characteristics of the resulting emulsion were as shown in Table 1.

(Example 3) (Comparative) 8% gelatin solution was placed in a 400rnti reaction vessel and p
Ag 8.0% & degree 50℃, p) 16.4,
2M AgNOs bath solution and 2M NaC2 bath akmm2m
Mixed for 1 minute at t/min. Thereafter, 2 M
Instead of the ON aC2 solution, it was simultaneously mixed with a 2M AgNO3 solution at a flow rate of 3ml/ml for 40 minutes. While mixing.

The pAg gold in the reaction vessel was maintained at 8.0, the temperature at 50° C., and p)i at 6.4. Most of the obtained chlorinated grains were non-tabular grains.

As can be seen from Examples 1 to 3, the presence of a thiourea derivative is essential for the production of silver chloride tabular grains, and the minimum amount of time necessary for the production of tabular grains is the mixing of a halogen solution and a silver salt solution. It must be filled instantaneously and at the beginning of mixing, in other words at the time of the first nucleation of the particles.

(Example 4) 400-tL of gelatin solution (6% gelatin) was
Keep at 0°C. Exemplary compounds of OIM (3M including lla-
pAg 'i 7.8 using KcL solution of υ-1m
Mother liquor A was obtained. A 2M KcL solution containing 0.005M of Exemplified Compound (1) and a 2M silver nitrate solution were added to this mother liquor by a double jet at a constant flow rate (5 d/mi).
n) for 30 minutes. During the addition, the temperature of mother liquor A was 40
C, p)1 was maintained at 7 and O, pAg at 7.8. The grain characteristics of the obtained emulsion are shown in Table 1.

(Example 5) Example compound (5) was substituted for example compound (1) in Example 4.
) was used to prepare an emulsion. The grain characteristics of the emulsion obtained are shown in Table 1.

(Example 6) A 400-gelatin solution (8% gelatin) was kept at 50°C and 0. NaCt containing OIM exemplary compound (11)
The pAgi was adjusted to 8.5 using solution (3M)'i (
Mother liquor B). While maintaining the temperature at 50°C and pH 5, add 2M NaC containing 0.01M exemplified compound (11) to mother liquor B.
L solution and 2M AgNO3 solution were added by double jet at constant flow rate (3tnvmin) for 1 minute.

Then increase the addition rate (from start to finish 5
2M AgN03 solution was added until 300-fold was consumed. The grain characteristics of the obtained emulsion are shown in Table 1.

(Example 7) 8% gelatin solution was placed in a 400 d'i reaction vessel, 0,
2M0NaCA containing OOIM exemplary compound (17)'
Using the solution, pAg! After adjusting to 8.5, 2M
Ag 1'J 05 solution 240- and 2M NaCA solution (containing 0,001M exemplified compound (17)) 240-
- was added over 40 minutes using a metering pump. During the addition, the pA-g in the reaction vessel was kept at 85, the temperature at 50°C, and p
It was maintained at ut-6,4. The grain characteristics of the obtained emulsion are shown in Table 1.

(Example 8) In place of the Kct solution used in Example 4, Ct:Br=8
:2 Mixed solution of NaCL solution and KBr solution Kongoi, F
mAg l9. An emulsion was prepared under the same conditions as in Example 4 except that the temperature was maintained at O. The grain characteristics of the obtained emulsion are shown in Table 1. In addition, the chromogen composition of these tabular grains was investigated by 2X-ray diffraction and was found to be Ct:Br=8:2.
The composition of the halogen solution used was directly reflected in the halogen composition of the emulsion grains.

(Example 9) 2M AgN0. solution and 710gen solution (2M NaCl solution tL120- and 2M0KBr solution 1
2M! :t-addition,ttrimono,C2:Br=1:1)
and were simultaneously mixed for 60 minutes at a flow rate of 4 ml/min. During mixing, the pAg 'i in the reaction vessel was maintained at 9.5, the temperature at 55° C., and the pH at 7.0. The grain characteristics of the obtained emulsion are shown in Table 1.

(Margin below) As can be seen from the above results, the present invention made it possible to easily produce a silver halide photographic emulsion consisting mostly of tabular grains mainly composed of silver chloride with a high aspect ratio and with good reproducibility. .

4. Effects of the Invention According to the present invention, a more advantageous method than the conventional method for producing tabular grains mainly composed of silver chloride and having a high aspect ratio has been proposed. The present invention is operationally simpler than prior art processes for obtaining high aspect ratio, entirely chloride-based tabular grains.

Although not compatible with the practice of the present invention, in order to obtain tabular grains, there is no need to prepare seed crystals, and precipitation conditions 'f during the nucleation and growth process of emulsion precipitation.
There is no need to convert r:f, and there is almost no change in the pH in the reaction vessel during this time, so the third jet for pH maintenance is substantially unnecessary.

Claims (1)

[Claims] (1) A halide and silver salt solution are mixed in the presence of thiourea or a thiourea derivative, and approximately 50%
Tabular silver halide grains containing at least mol % chloride and having an average aspect ratio greater than 5:1 and having opposing parallel {111} major crystal faces account for at least 60% of the total grain projected area. A method for producing a silver halide photographic emulsion, which comprises producing a silver halide emulsion that accounts for %.