JPS648324B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Field of the Invention The present invention is useful in the field of photography. The first invention of this application relates to a radiation-sensitive silver halide photographic emulsion containing a dispersion medium and silver chloride grains. The second invention of this application includes a dispersion medium and silver chloride particles, and at least 50% of the total projected area of the silver chloride particles is
A radiation-sensitive halogenated photographic emulsion is comprised of tabular grains containing no internal bromide or iodide, having an average aspect ratio greater than 8:1, and having opposing parallel {111} main crystals. ,
This invention relates to a method for producing chloride and silver salt solutions by simultaneously introducing them into a dispersion medium in the presence of ammonia by a double jet method. (b) Prior Art Radiation-sensitive silver halide photographic emulsions are known and offer particular advantages. For example, it has lower negative sensitivity to the visible portion of the spectrum than other photographically useful silver halides. moreover,
Silver chloride is more soluble than other photographically useful silver halides, so development and fixing can be accomplished in a shorter time. It is well recognized by those skilled in the art that silver chloride is extremely prone to forming crystals having {100} crystal faces. In the overwhelming majority of photographic emulsions, silver chloride crystals, if present, are in the form of cubic grains. Although with some difficulty, it has been possible to change the crystalline properties of silver chloride. Claes et al.
Modification of crystal properties of Agcl (Crystal Habit
Modification of Agcl by Impurities
"Determing the Solvation", The Journal
Of Photographic Science, vol. 21,
39-50, 1973, teaches the formation of silver chloride crystals with {110} and {111} faces through the use of various grain growth modifiers. wyrsch describes the ``Sulfur Sensitization of Monosized Silver Emulsions with {111}, {110} and {100} Crystal Characteristics''.
Chloride Emulsions with {111}, {110}and
{100}Crystal Habit)'', Paper 13, International Congress of Photographic Science, pp. 122-124, 1978
disclosed a triple jet precipitation process in which silver chloride was precipitated in the presence of ammonia and small amounts of divalent cadmium ions. Control of pAg and PH in the presence of cadmium ions resulted in rhombidodecahedral {110}, octahedral {111}, and cubic {100} crystal properties. Although tabular silver bromide grains have been extensively studied, they have been mostly macro-sized and unavailable for photographic applications. Tabular grains herein refer to grains having two parallel or substantially parallel crystal faces that are substantially larger than any other single crystal face of the grain. The aspect ratio (ie, diameter to thickness ratio) of the tabular grains is substantially greater than 1:1. High aspect ratio tabular grain silver bromide emulsions were developed by Cugnac and Chateau, "Evolution of the Morpology of Silver Bromide Crystals Upon Physical Ripening".
Silver Bromide Crystals During Physical
Ripening)”, Science and Industry Photography, Vol. 33, No. 2 (1962),
Reported on pp.121-125. From 1937 to the 1950s, Eastman Kodatsu manufactured Duplicated® radiographic film products with no-screen, X-ray codes.
It was sold under the name 5133. This product had sulfur sensitized silver bromide emulsion coating layers on opposite major sides of the film support. This emulsion was not spectrally sensitized as it was intended for exposure to X-ray radiation. The tabular grains had an average aspect ratio of about 5-7:1. Tabular grains account for more than 50% of the projected area of these grains,
Nontabular grains accounted for more than 25% of the projected area. After duplicating these emulsions several times,
The emulsion with the highest average aspect ratio exhibited an average tabular grain diameter of 2.5 micrometers, an average tabular grain thickness of 0.36 micrometers, and an average aspect ratio of 7:1. Other reproductions have thicker emulsions;
The tabular grains were larger in diameter and had a smaller average aspect ratio. Although tabular grain silver iodobromide emulsions are known in the photographic industry, none are known to exhibit high average aspect ratios. Tabular silver iodobromide grains are produced by Duffin, Photographic Emulsion Chemistry, Focal Press, 1966, pp. 66-72 and Trivelli and Smith, Iodobromide Precipitation. Effect of silver iodide on the structure of series (The
Effect of Silver Iodide Upon the Structure
of Bromo-Iodide Precipitation Series),
The Photography Journal, LXXX
Volume, July 1940, pp. 285-288.
Tribelli and Smith observed a significant reduction in both grain size and aspect ratio with the introduction of iodide. Gutoff, Nucleation and Growth Rates in the Precipitation Formation of Silver Halide Photographic Emulsions.
During the Precipitation of Silver Halide
"Photographic Emulsions", Photographic Sciences and Engineering, Vol. 14, No. 4, 1970, July-August, pp. 248-
257, the preparation of silver bromide and silver iodobromide emulsions of the type prepared by single jet precipitation using a continuous precipitation apparatus is reported. Advantages in covering power and other photographic properties can be obtained by preparing silver halide emulsions in which the grains are tabular (i.e., spread out in two dimensions compared to their thickness). It is recognized that U.S. Pat. No. 4,063,951 discloses that by controlling the pAg within the range of 5.0 to 7.0 and performing double-jet precipitation techniques, 1.5
It is taught to form tabular silver halide crystals with an aspect ratio (based on edge length) of ˜7:1. No. 3 of U.S. Patent No. 4,063,951
As shown in the figure, the formed silver halide grains exhibit characteristics of {100} crystal planes, with square and rectangular major faces. Lewis U.S. Patent No.
No. 4067739 describes forming seed crystals, increasing the size of the seed crystals by Ostwald ripening in the presence of a silver halide solvent, and renucleation or Ostwald ripening while controlling pBr (the reciprocal of the logarithm of the bromide ion concentration). The preparation of single-dimensional silver halide emulsions with predominantly twinned octahedral crystals is described by completing grain growth without ripening. US Pat. No. 4,067,739 does not mention silver chloride. US Patent No.
4150994 and 4184877, UK patent no.
No. 1570581 and DE 2905655 and DE 2921077 teach the formation of flat twinned octahedral silver halide grains by using seeds of at least 90 mol % iodide. There is. Unless otherwise specified, all halide percentages herein are based on the silver present in the corresponding emulsion, grain, or grain region. For example, particles consisting of silver iodobromide containing 40 mol% iodide are also 60
Also includes mole percent bromide. Japanese Patent Publication No. 55-
No. 142329 (November 6, 1980), U.S. Patent No.
4150994, but is not limited to the use of silver iodide as the seed grain. U.S. Pat. No. 3,784,381 has a range of 5 to 9.
It is taught to prepare silver iodochloride and silver iodobromochloride emulsions by precipitating silver halide grains at a pH and a pAg of at least about 7.8. Precipitation is carried out by adding to the precipitation mixture, prior to the end of the precipitation, a weak solvent for the silver halide selected from the group consisting of ammonium chloride, ammonium nitrate and magnesium chloride. (c) Disclosure of the Invention An object of the present invention is to provide a radiation-sensitive silver halide photographic emulsion containing a dispersion medium and silver chloride grains, and a method for producing the same. This emulsion can provide improved sharpness when incorporated into multilayer photographic elements, provides a better speed-granularity relationship when optimally sensitized chemically and spectroscopically, and provides blue , can exhibit improved separation of sensitivity between the spectrally sensitized region of the spectrum and the ultraviolet region of the spectrum when incorporated into green and/or red sensitized photographic elements. In the first invention of this application, this object is achieved by a radiation-sensitive silver halide photographic emulsion of the type described above, in which at least 50% of the total projected area of said silver chloride grains contain bromide and iodide. The grains are characterized in that they are substantially free of , have an average aspect ratio greater than 8:1, and are dominated by tabular grains having opposing, parallel {111} principal crystal faces. Aspect ratio is defined as the ratio of particle diameter to thickness. In the second invention of this application, this object comprises a dispersion medium and silver chloride grains, wherein at least 50% of the total projected area of said silver chloride grains are free of bromide and iodide internally and have a ratio of 8:1. A radiation-sensitive silver halide photographic emulsion dominated by tabular grains having a large average aspect ratio and opposing parallel {111} principal crystal planes was prepared by a double-jet process with a chloride and silver salt solution. This method maintains the pAg in the dispersion medium in the range of 6.5 to 10 during the simultaneous introduction of chloride and silver salt solutions. , is characterized by maintaining the pH in the dispersion medium in the range of 8 to 10. In one preferred embodiment, the present invention is directed to substantially pure silver chloride grains having relatively high aspect ratio grains and their production. Advantages may also be obtained by incorporating the emulsions of the present invention into the disclosed image transfer film units. This image transfer film unit has a higher ratio of photographic speed to silver coverage (i.e., silver halide coverage per unit area), and a visible transfer image is achieved more quickly.
A transferred image with higher contrast can be provided with shorter development time. The radiation-sensitive emulsion of the present invention consists of a dispersion medium and tabular silver chloride grains containing neither bromide nor iodide therein. To obtain the benefits of tabular grains, the grains are preferably relatively thin and have relatively high aspect ratios. As used herein, the term "aspect ratio" means the ratio of a particle's diameter to its thickness. On the other hand, the "diameter" of a particle is defined as the diameter of a circle with an area equal to the projected area of the particle seen in a micrograph of an emulsion sample. The term "projected area" is used interchangeably with the terms "projection area" and "projective area" commonly used by those skilled in the art (see, e.g., James and Higgins, "Photograph Fundamentals
of Photographic Theory)”, Morgan &
Morgan, New York, p. 15). The tabular grains of the present invention have an average aspect ratio of greater than 8:1, preferably at least 10:1. Under optimal growth conditions, aspect ratios of 20:1 or higher are possible. Of course, the thinner the particles, the higher the aspect ratio for a given diameter. Typically, particles with a desirable aspect ratio are those with an average thickness of less than 0.80 micrometers. Typically, tabular grains have a thickness of at least 0.10 micrometer. However, in principle it is also possible to produce thinner tabular grains. At least 50%, preferably at least 75%, of the silver chloride grains in the emulsion according to the invention, based on the total projected area of the grains, are present in the form of tabular grains.
Tabular grains have opposing parallel {111} major crystal faces, typically triangular or truncated.
Surprisingly, these tabular grains appear to have the same morphology as silver bromide and silver iodobromide tabular grains. That is, the major faces and edges of the tabular grains in the emulsion of this invention are both {111}
It appears to be defined by crystal planes. The tabular silver chloride grains according to the present invention do not contain bromide or iodide. In other words,
The tabular grains consist essentially of initially formed silver chloride. The presence of bromide during grain formation, even in small amounts, interferes with the formation of the desired tabular morphology. The presence of iodide during the formation of silver chloride grains tends to reduce the resulting aspect ratio and results in the formation of a higher proportion of non-tabular grains. The requirement that the tabular grains consist essentially of silver chloride in their interior does not exclude the presence of bromide and/or iodide in the tabular grains. Once tabular silver chloride grains are formed according to the method of the present invention, other halides may be incorporated into the grains by processes well known to those skilled in the art. Techniques for forming silver halide shells are described in U.S. Pat. No. 3,367,778, U.S. Pat.
Same No. 3917485, Same No. 4150994, and Same No.
4184887, UK Patent No. 1570581 and German Patent Publication Nos. 2905655 and 2921077. Since conventional techniques for shell formation do not favor the formation of high aspect ratio tabular grains, the average aspect ratio of the emulsion decreases as shell growth proceeds. If conditions exist in the reaction vessel that favor the formation of tabular grains during shell formation, shell growth will occur primarily on the outer edges of the grains, so the aspect ratio will not be reduced.
Silver iodobromide can be precipitated in the annular region of the tabular grains without necessarily reducing the aspect ratio of the resulting grains. The tabular grain regions containing silver, chloride, and bromide are prepared during introduction of the silver, chloride, bromide, and optionally iodide salts into the reaction vessel in a molar ratio of chlorine and bromide ions of 1.6 to about 260:1. and the total concentration of halogen ions in the reaction vessel is 0.10 to 0.90.
It is formed by keeping it within a normal (defined) range. The molar ratio of silver chloride to silver bromide in the tabular grains may range from 1:99 to 2:3. High aspect ratio core-shell tabular grain emulsions can be prepared for use in forming direct reversal images. By adding both the halide and the silver salt after formation of the tabular silver chloride grains, the original grains remain intact but act as nuclei for the precipitation of additional silver halide. The resulting tabular grains are still free of both bromide and iodine ions. When bromine and/or iodine salts are added to emulsions containing tabular silver chloride grains without the addition of silver salts, the heavier halide will replace chloride in the silver chloride crystal structure. The turnover begins at the crystal surface and progresses toward the interior of the particle. It is well known that chloride ions in the silver chloride crystal lattice are replaced by bromide ions and sometimes small amounts of iodine ions. Such emulsions are known to those skilled in the art as halide-modified silver halide emulsions. Techniques for making halide modified emulsions and their uses are described in US Pat. In the present invention, less than 20 mol%, preferably less than 10%, of halide is introduced by substitution. As the level of substitution increases, the tabular morphology of the grains is reduced or even destroyed. Thus, although it is possible to replace chloride ions with bromine and/or iodine ions at or near the particle surface, the production of internal latent image-forming particles does not involve the usual extensive halide modification. do not have. In forming tabular silver chloride grains according to this invention, an aqueous dispersion medium is placed in a conventional silver halide reaction vessel. PH of the dispersion medium in the reaction vessel and
pAg is adjusted to satisfy the precipitation conditions according to this invention. PH, pCl and pAg used here
are defined as the negative logarithms of the hydrogen, chlorine, and silver ion concentrations, respectively. The range of pAg values that can be used to implement this invention is the equivalence point (pAg at which the concentrations of silver and halogen ions are stoichiometrically equal).
Since it is on the halide side, a small amount of chlorine salt aqueous solution is used initially to adjust the pAg. Then, the silver salt aqueous solution and the chlorine salt aqueous solution are simultaneously introduced into the reaction vessel. The pAg within the reaction vessel is maintained within the desired range by conventional measurement techniques and by adjusting the relative flow rates of the silver salt and chlorine salt solutions. The PH in the reaction vessel is also monitored using conventional detection techniques and kept within a predetermined range by the addition of base while the silver and chlorine salts are introduced.
Apparatus and technique for controlling pAg and PH during silver halide precipitation is disclosed in U.S. Pat. No. 3,031,304.
No. 3821002 and Claes and Peelaers, Fotographische Correspodants, 103161 (1967). It is believed that the presence of ripening agents, particularly ammonia, contributes to the formation of tabular silver chloride grains according to this invention. In order to meet the PH requirements of the precipitation process, it has been found convenient to feed the reaction vessel with aqueous ammonium hydroxide. As generally recognized, ammonia exists in an equilibrium relationship in an aqueous ammonium hydroxide solution. Ammonium hydroxide in aqueous solution may be obtained by direct addition of ammonium hydroxide or by addition of a water-soluble ammonium salt such as ammonium chloride or ammonium nitrate and an alkali metal hydroxide, such as a strong base such as sodium or potassium hydroxide. I can do it. Ammonium hydroxide is preferably added to the reaction vessel via a third jet at the same time as the silver salt and halogen salt addition. Alternatively, ammonium hydroxide may be combined with an aqueous solution of a silver salt or halide salt during the addition. Useful tabular silver chloride emulsions according to the invention include:
At normal silver chloride precipitation temperatures below about 60°C,
pAg value 6.5 to 10 (preferably 7.0 to 9.4)
range, and the pH value is between 8 and 10 (preferably
8.5 to 9.7). Of course, higher conventional precipitation temperatures can also be used, but in this case larger sized tabular grains are provided. In the best practice of this invention, pAg
is maintained in the range of 7.6 to 8.9 within the reaction vessel while introducing ammonium hydroxide into the reaction vessel in an amount sufficient to maintain the pH in the range of 8.8 to 9.5 during the introduction of the chlorine salt solution. . Optimally, the temperature of the reaction vessel is maintained in the range of 20 to 40°C. At least 50% of the silver halide precipitated by the above process is in the form of tabular grains, based on projected grain area. Preferably, at least 75% of the projected area of all grains present are in the form of tabular grains. Although small amounts of non-tabular grains are perfectly suited for many photographic applications, the proportion of tabular grains is increased to achieve the full benefits of tabular grains. The large tabular silver chloride grains are separated from the smaller non-tabular grains in the mixed grains using conventional separation techniques such as centrifugation or wet cyclones. The teaching of wet cyclone separation is published in U.S. Patent No.
It is written in No. 3326641. Other than as specifically stated above, methods for preparing tabular grain silver chloride emulsions can take a variety of conventional forms. Soluble silver salts, such as silver nitrate, can be used in the silver salt aqueous solution, while
The aqueous chlorine salt solution contains one or more water-soluble ammonium, alkali metals (e.g., sodium or urium), or alkaline earth metals (e.g.,
Chlorine salts of magnesium or calcium can be used. Silver and chlorine salt aqueous solutions have a concentration of 0.1
It can vary widely from 7.0 to 7.0 moles or more. In addition to adding silver and chloride salts to the reaction vessel, it is known to be useful for a variety of other compounds to be present in the reaction vessel during silver halide precipitation. For example, low concentrations of compounds of metals such as copper, thallium, lead, bismuth, cadmium, gold, and group noble metals can be present during precipitation of silver halide emulsions, as described in U.S. Pat.
No. 1195432, No. 1951933, No. 2448060, No. 2628167, No. 2950972, No. 3488709, No. 3737313, and Research Disclosure, Volume 134, June 1975, Section 13452. has been done. The distribution of metal dopants in the silver chloride grains can be controlled by selective placement of metal compounds in the reaction vessel or by controlled addition during the introduction of silver and chloride salts. The respective silver salts and halide salts are described in U.S. Pat. so that the distribution ratio is adjusted and the reactor contents are
To regulate PH, pCl and/or pAg,
It can be added to the reactor through surface or subsurface feed pipes using a distribution device or using gravimetric feed. U.S. Pat. No. 2,996,287;
No. 3415605, No. 3785777, No. 3785777, No. 3415605, No. 3785777, No.
4147551 and 4171224, UK Patent Application No.
2022431, DE 2555364 and DE 2556885 and Research Disclosure, Vol. 166, February 1978, Item 16662 can be used. . Research Disclosure and its predecessor Product Licensing
The Index is a publication of Industrial Opportunities Limited, PO9-1EF, Hampshire, Herband, Homewell, UK. In the preparation of tabular grain silver chloride emulsions, the dispersion medium is initially placed in the reactor. In a preferred form, the dispersion medium consists of an aqueous dispersion of a peptizer. Peptizer concentrations of 0.2 to about 10% by weight based on the total weight of emulsion components in the reactor can be employed. The concentration of peptizer in the reaction vessel is adjusted before or during particle formation.
Preferably, it is kept below about 6% by weight, based on total weight. Maintaining the peptizer concentration in the reactor less than about 6% by total weight before and during silver halide production and adding emulsion vehicle afterwards to obtain optimum coating properties. It is a common practice to adjust the emulsion vehicle concentration to a high concentration by adjusting the concentration of the emulsion vehicle. The initially formed emulsion may contain from about 5 to 50 grams of peptizer, preferably from about 10 to 30 grams, per mole of silver halide. Additional vehicle can be added later to increase its concentration per mole of silver halide.
It can be increased to a high value of 1000g.
Preferably the vehicle concentration in the final emulsion is greater than 50 grams per mole of silver halide. Preferably, the vehicle accounts for about 30 to 70 percent by weight of the emulsion layer during coating and drying during the fabrication of the photographic element. Vehicles (including both binders and peptizers) can be selected from those commonly used in the preparation of silver halide emulsions. Preferred deflocculants are hydrophilic colloids, which can be used alone or in combination with hydrophobic substances. Suitable hydrophilic substances include proteins, protein derivatives, e.g. cellulose derivatives such as cellulose esters, gelatins such as alkali-processed gelatin (cow bone or leather gelatin) or acid-processed gelatin (pig skin gelatin), e.g. acetylated Included are materials such as gelatin and gelatin derivatives such as phthalated gelatin. These and other vehicles and vehicle spreading agents are described in Research Disclosure, Vol. 176, 1978, 12
May, Item 17643, Sec. In particular, vehicle materials, including hydrophilic colloids (as well as hydrophobic materials used therewith), can be used not only in the emulsion layers of photographic elements of the present invention, but also in other layers such as overcoat layers, interlayers, and layers located below the emulsion layers. It can be blended into the layer. Grain ripening may occur during the preparation of the silver halide emulsion according to the present invention. Due to its high solubility level, silver chloride is less affected by ripeners than other silver halides. Known silver halide solvents are useful in promoting ripening. For example, the ripening agent can be incorporated in its entirety into the dispersion medium in the reactor before adding the silver and halide salts, or one or more halide salts, silver salts, or peptizers can be added. It can also be introduced into the reactor. As a further variant, the ripening agent can also be introduced independently at the halide salt and silver salt addition stages. The high aspect ratio tabular grain emulsions of this invention are preferably washed to remove soluble salts. Removal of soluble salts can be accomplished by well-known methods such as tilting, overflow, and/or cold settling and leaching, as described in Research Disclosure, Volume 176, December 1978, Section I Am 17643. This can be done using different techniques. Research Disclosure, Volume 101, September 1972,
Prior to use, the emulsion with or without sensitizer is dried and stored as described in Item 10152. In the present invention, in order to avoid an increase in the thickness of the tabular grains, a reduction in the aspect ratio, and/or an excessive increase in the diameter, cleaning is carried out at the end of ripening of the tabular grains after precipitation is completed. This is particularly advantageous. The high aspect ratio tabular grain silver halide emulsions of this invention are chemically sensitized. chemical sensitization
THJames, The Theory of the Photographic Process, 4th edition, Macmillan,
1977, pp. 67-76, and can also be carried out using research
Disclosure, Volume 120, April 1974, Item 12008, Research Disclosure, 134
Volume, June 1975, Item 13452, U.S. Patent No.
No. 1623499, No. 1673522, No. 2399083, No. 2642361, No. 3297447, No. 3297446,
Same No. 3772031, Same No. 3761267, Same No. 3857711,
No. 3565633, No. 3901714 and No. 3901714
3904415 and British Patent No. 1315755 and
pAg5~10, PH5~ as described in No. 1396696
8 and temperatures from 30 to 80 DEG C. using sulfur, selenium, tellurium, gold, platinum, palladium, iridium, osmium, rhodium, rhenium or phosphorus sensitizers or combinations of these sensitizers. Chemical sensitization is optimally performed as described in U.S. Patent No.
No. 2,642,361 in the presence of thiocyanate compounds and in the presence of sulfur-containing compounds of the type described in US Pat. Finishing (Chemical Sensitization) Can be chemically sensitized in the presence of modifiers. Finish modifiers used include azaindene, azapyridazine, azapyrimidine,
Compounds known to suppress fog and increase sensitivity in the process of chemical sensitization are used, such as benzothiazolium salts and sensitizers having a heterocyclic nucleus. Examples of finish modifiers include U.S. Pat.
2131038, 3411914, 3554757, 3565631 and 3901714, Canadian Patent No.
No. 778723 and Duffin, Photographic Emulsion Chemistry, Focal Press (1966), New York, pp. 138-
143. In addition to or in place of chemical sensitization, U.S. Pat.
Reduction sensitization can be carried out using, for example, hydrogen, as described in US Pat. No. 3,983,609, Oftedahl et al., Research Disclosure, Vol.
May, Item 13654, U.S. Patent No. 2,518,698, Id.
No. 2739060, No. 2743182, No. 2743183, No. 3026203 and No. 3361564 with reducing agents such as stannous chloride, thiourea dioxide, polyamines and amine borane; pAg (e.g. less than 5) and/or high PH
(e.g. greater than 8) treatment can be reduction sensitized. U.S. Patent No. 3917485 and
Surface chemical sensitization can be performed, including subsurface sensitization as described in No. 3,966,476. In addition to chemical sensitization, the high aspect ratio tabular grain silver chloride emulsions of this invention can be spectrally sensitized. In combination with high aspect ratio tabular grain emulsions, spectral sensitizing dyes having absorption maxima in the blue and minus blue (i.e., green and red) portions of the visible spectrum can be used. Additionally, in special applications, spectral sensitizing dyes can be used to improve spectral sensitivity beyond the visible spectrum. For example, it is possible to use infrared absorption spectral sensitizers. The emulsions of this invention can be spectrally sensitized using various dyes. Dyes used include polymethine dyes including cyanine, merocyanine, complex cyanine and complex merocyanine (i.e. tri-, tetra- and polynuclear myanine and merocyanine), oxonol, hemioxonol, styryl, merostyryl and streptocyanine. It will be done. Cyanine spectral sensitizing dyes include quinolinium, pyridinium, isoquinolinium, 3H-indolium, benz[e]indolium, oxazolium, oxazolinium, thiazolium, thiazolinium, selenazolium, selenazolinium, imidazolium, imidazolinium, benzoxazolium. From the quaternary salts of Nium, benzothiazolium, benzoselenazolium, benzimidazolium, naphthoxazolium, naphthothiazolium, naphthoselenazolium, thiazolinium, dihydronaphthothiazolium, pyrylium and imidazopyrazinium It includes two chlorinated heterocyclic nuclei connected by a methine bond, as shown in FIG. Merocyanine spectral sensitizing dyes include barbituric acid, 2-thiobarbituric acid, rhodanine, hydantoin, 2-thiohydantoin, 4-thiohydantoin, 2-pyrazolin-5-one, 2-isoxazolin-5-one, indan -1,3-dione, cyclohexane-1,3-dione, 1,3-
dioxane-4,6-dione, pyrazoline-3,
5-dione, pentane-2,4-dione, alkylsulfonylacetonitrile, malononitrile,
Isoquinolin-4-one and chroman-2,4
-Includes an acidic nucleus derived from a dione and a cyanine dye-type basic heterocyclic nucleus bonded by a methine bond. One or more spectral sensitizing dyes can be used. Dyes are known that have maximum sensitivity at wavelengths over the entire length of the visible spectrum and have a wide variety of spectral sensitivity curve shapes. The selection and relative proportions of dyes will depend on the region of the spectrum in which sensitization is desired and the shape of the spectral sensitivity curve desired. Dyes with overlapping spectral sensitivity curves often exhibit a combined shape of the curves in which the sensitivity at each wavelength in the overlapping region is approximately equal to the sum of the sensitivities of the individual dyes. Therefore, by using a combination of a plurality of dyes having different maximum sensitivities, it is possible to obtain a spectral sensitivity curve having a maximum value between the maximum sensitivities of the individual dyes. Combinations of multiple spectral sensitizing dyes can be used, thereby supersensitizing, ie, using one of the spectral sensitizing dyes alone at any concentration in a given spectral region. Cyanine spectral sensitizing dyes include quinolinium, pyridinium, isoquinolinium, 3H-indolium, benz[e]indolium, oxazolium, oxazolinium, thiazolium, thiazolinium, selenazolium, selenazolinium, imidazolium, imidazolinium, benzoxazolium. From the quaternary salts of Nium, benzothiazolium, benzoselenazolium, benzimidazolium, naphthoxazolium, naphthothiazolium, naphthoselenazolium, thiazolinium, dihydronaphthothiazolium, pyrylium and imidazopyrazinium It includes two chlorinated heterocyclic nuclei connected by a methine bond, as shown in FIG. Merocyanine spectral sensitizing dyes include barbituric acid, 2-thiobarbituric acid, rhodanine, hydantoin, 2-thiohydantoin, 4-thiohydantoin, 2-pyrazolin-5-one, 2-isoxazolin-5-one, indan -1,3-dione, cyclohexane-1,3-dione, 1,3-
dioxane-4,6-dione, pyrazoline-3,
5-dione, pentane-2,4-dione, alkylsulfonylacetonitrile, malononitrile,
Isoquinolin-4-one and chroman-2,4
-Includes an acidic nucleus derived from a dione and a cyanine dye-type basic heterocyclic nucleus bonded by a methine bond. One or more spectral sensitizing dyes can be used. Dyes are known that have maximum sensitivity at wavelengths over the entire length of the visible spectrum and have a wide variety of spectral sensitivity curve shapes. The selection and relative proportions of dyes will depend on the region of the spectrum in which sensitization is desired and the shape of the spectral sensitivity curve desired. Dyes with overlapping spectral sensitivity curves often exhibit a combined shape of the curves in which the sensitivity at each wavelength in the overlapping region is approximately equal to the sum of the sensitivities of the individual dyes. Therefore, by using a combination of a plurality of dyes having different maximum sensitivities, it is possible to obtain a spectral sensitivity curve having a maximum value between the maximum sensitivities of the individual dyes. Combinations of multiple spectral sensitizing dyes can be used, thereby supersensitizing, ie, using one of the spectral sensitizing dyes alone at any concentration in a given spectral region. Cyanine spectral sensitizing dyes include quinolinium, pyridinium, isoquinolinium, 3H-indolium, benz[e]indolium, oxazolium, oxazolinium, thiazolium, thiazolinium, selenazolium, selenazolinium, imidazolium, imidazolinium, benzoxazolium. From the quaternary salts of Nium, benzothiazolium, benzoselenazolium, benzimidazolium, naphthoxazolium, naphthothiazolium, naphthoselenazolium, thiazolinium, dihydronaphthothiazolium, pyrylium and imidazopyrazinium It contains two chlorinated heterocyclic nuclei connected by a methine bond, as shown in FIG. Merocyanine spectral sensitizing dyes include barbituric acid, 2-thiobarbituric acid, rhodanine, hydantoin, 2-thiohydantoin, 4-thiohydantoin, 2-pyrazolin-5-one, 2-isoxazolin-5-one, indan -1,3-dione, cyclohexane-1,3-dione, 1,3-
dioxane-4,6-dione, pyrazoline-3,
5-dione, pentane-2,4-dione, alkylsulfonylacetonitrile, malononitrile,
Isoquinolin-4-one and chroman-2,4
-Includes an acidic nucleus derived from a dione and a cyanine dye-type basic heterocyclic nucleus bonded by a methine bond. One or more spectral sensitizing dyes can be used. Dyes are known that have maximum sensitivity at wavelengths over the entire length of the visible spectrum and have a wide variety of spectral sensitivity curve shapes. The selection and relative proportions of dyes will depend on the region of the spectrum in which sensitization is desired and the shape of the spectral sensitivity curve desired. Dyes with overlapping spectral sensitivity curves often exhibit a combined shape of the curves in which the sensitivity at each wavelength in the overlapping region is approximately equal to the sum of the sensitivities of the individual dyes. Therefore, by using a combination of a plurality of dyes having different maximum sensitivities, it is possible to obtain a spectral sensitivity curve having a maximum value between the maximum sensitivities of the individual dyes. Combinations of multiple spectral sensitizing dyes can be used, thereby supersensitizing, ie, using one of the spectral sensitizing dyes alone at any concentration in a given spectral region. Cyanine spectral sensitizing dyes include quinolinium, pyridinium, isoquinolinium, 3H-indolium, benz[e]indolium, oxazolium, oxazolinium, thiazolium, thiazolinium, selenazolium, selenazolinium, imidazolium, imidazolinium, benzoxazolium. From the quaternary salts of Nium, benzothiazolium, benzoselenazolium, benzimidazolium, naphthoxazolium, naphthothiazolium, naphthoselenazolium, thiazolinium, dihydronaphthothiazolium, pyrylium and imidazopyrazinium It includes two chlorinated heterocyclic nuclei connected by a methine bond, as shown in FIG. Merocyanine spectral sensitizing dyes include barbituric acid, 2-thiobarbituric acid, rhodanine, hydantoin, 2-thiohydantoin, 4-thiohydantoin, 2-pyrazolin-5-one, 2-isoxazolin-5-one, indan -1,3-dione, cyclohexane-1,3-dione, 1,3-
dioxane-4,6-dione, pyrazoline-3,
5-dione, pentane-2,4-dione, alkylsulfonylacetonitrile, malononitrile,
Isoquinolin-4-one and chroman-2,4
-Includes an acidic nucleus derived from a dione and a cyanine dye-type basic heterocyclic nucleus bonded by a methine bond. One or more spectral sensitizing dyes can be used. Dyes are known that have maximum sensitivity at wavelengths over the entire length of the visible spectrum and have a wide variety of spectral sensitivity curve shapes. The selection and relative proportions of dyes will depend on the region of the spectrum in which sensitization is desired and the shape of the spectral sensitivity curve desired. Dyes with overlapping spectral sensitivity curves often exhibit a combined shape of the curves in which the sensitivity at each wavelength in the overlapping region is approximately equal to the sum of the sensitivities of the individual dyes. Therefore, by using a combination of a plurality of dyes having different maximum sensitivities, it is possible to obtain a spectral sensitivity curve having a maximum value between the maximum sensitivities of the individual dyes. Multiple spectral sensitizing dyes can be used in combination, thereby producing supersensitization, i.e. greater sensitization in a given spectral region than if one of the spectral sensitizing dyes were used alone at any concentration.
Also, greater spectral sensitization is achieved than that resulting from the additive effects of these spectral sensitizing dyes. Supersensitization consists of selected combinations of spectral sensitizing dyes and other additives such as stabilizers and antifoggants, development accelerators or inhibitors, coating aids, fluorescent brighteners, and antistatic agents. achieved by.
Some of the mechanisms and compounds that may be responsible for supersensitization are discussed in Gilman,
“Review of the supersensitization mechanism”
"Mechanisms of Supersensitization", Photographic Science and Engineering, Vol. 18, 1974, pp. 418-430. Spectral sensitizing dyes also affect emulsions in other ways. In addition, the spectral sensitizing dye is
Acts as a halogen acceptor or electron acceptor, an antifoggant or stabilizer, a development accelerator or inhibitor as disclosed in Nos. 2131038 and 3930860. Among the spectral sensitizers useful for sensitizing silver halide emulsions are Research Disclosure,
Volume 176, December 1978, Amtei 17643, Section. When iodide is used to improve spectral sensitization, it can replace the halide present on the grain surface, thereby converting the grain to a silver iodohalide grain. Amounts of dye conventionally used for spectrally sensitizing emulsion layers containing non-tabular silver halide grains can be used. To achieve the full benefits of the invention,
It is desirable to have an optimum amount of spectral sensitizing dye (ie, an amount sufficient to achieve at least 60% of the maximum photographic sensitivity achievable from the grain under the exposure conditions) on the tabular grain surfaces. The amount of dye used will vary based on the particular dye or combination of dyes used and the particle size and aspect ratio. Optimum spectral sensitization occurs when the total available surface area of the surface-sensitized silver halide grains is approximately 25 to
It is known in the photographic art that monolayer coverages equal to or greater than 100% can be achieved when using organic dyes. That is,
For example, West et al., ``The Adsorption of Sensitizing Dyes in Photographic Emulsions''
of Sensitizing Dyes in Photographic
Emulsions), Journal of Physical
Chemistry, vol. 56, p. 1065, 1952; Spence et al., “Desensitization of Sensitizing Dyes,” Journal of Physical and Colloids.
Chemistry, Volume 56, No. 6, June 1948,
pp. 1090-1103; and US Pat. No. 3,979,213. Optimal dye density levels are determined by Mees, Theory of the Photographic Process, 1942, Macmillan, pp. 1067-
1069, by the method taught in . Spectral sensitization can be performed at any stage of emulsion preparation known to be useful. Most commonly, spectral sensitization is performed subsequent to completion of chemical sensitization. However, spectral sensitization can be performed simultaneously with chemical sensitization as taught in U.S. Pat.
Alternatively, spectral sensitization can be carried out completely prior to chemical sensitization, and furthermore, spectral sensitization can be started before the completion of silver halide grain precipitate formation. US Patent No. 4225666
As taught in No. 1, the spectral sensitizing dye is introduced into the emulsion separately, i.e., a portion of the spectral sensitizing dye is present prior to chemical spectral sensitization and the remainder is present after chemical sensitization. It is possible to introduce Unlike U.S. Pat. No. 4,225,666, silver halide
Spectral sensitizing dyes can be added to the emulsion after % has been precipitated. Sensitization can be enhanced by pAg modulation, including circulation during chemical and/or spectral sensitization. Examples of pAg regulation are described in Research Disclosure, Volume 181, May 1979, Item 18155. Chemical sensitization of spectrally sensitized high aspect ratio tabular grain emulsions can be accomplished at one or more predetermined discrete edge locations of the tabular grains. By preferentially adsorbing the spectral sensitizing dye to the crystal surfaces forming the major surfaces of the tabular grains, chemical sensitization occurs at different crystal surfaces along the edges and preferably at the corners of the tabular grains. It seems that this can occur selectively. Although not necessary to achieve all advantages, the emulsions of this invention are optimally chemically and spectrally sensitized according to typical practical manufacturing methods.
That is, it is desirable to achieve a sensitivity corresponding to at least 60% of the maximum log sensitivity achieved from those particles in the sensitized spectral region under possible use and processing conditions. Here, log sensitivity means 100 (1-logE), and in this formula, E
is the exposure amount that can be expressed in meters-candle-seconds at a density of 0.1 above fog. Once the silver halide grains in the emulsion layer have been characterized, whether the emulsion layer of a given product is optimally chemically and spectrally sensitized relative to comparable products from other manufacturers can be determined by further product analysis. This can be determined by performing a performance evaluation. To achieve the sharpness benefits of the present invention, it is immaterial whether the silver halide emulsion is chemically or spectrally sensitized efficiently or inefficiently. As mentioned above, a high aspect ratio tabular grain emulsion is once produced by the precipitation method, and then washed.
Once sensitized, their preparation can be completed by incorporating commonly used photographic additives. These can then be applied in photographic applications where silver images are to be produced, for example in conventional black and white photography. Photographic elements intended to form silver images using the emulsions of this invention can be sufficiently hardened that no additional hardeners need to be incorporated during processing. This hardening can increase silver coverage compared to photographic elements that are similarly hardened and processed but use tabular grain emulsions that are nontabular or have lower aspect ratios than high aspect ratios. can. In particular, high aspect ratio tabular grain emulsion layers and other hydrophilic colloid layers of black and white photographic elements are
They can be hardened sufficiently to reduce the degree of swelling of those layers to less than 200%. where % swelling is determined by (a) maintaining the photographic element at 38°C and 50% relative humidity for 3 days, (b) measuring the layer thickness, and (c) placing the photographic element in distilled water at 20°C. Soak for 3 minutes, then
(d) Determined by measuring layer thickness changes. Although it is particularly desirable to harden photographic elements intended for the formation of silver images to such an extent that no hardening agent is required in the processing solution, the degree of hardening of the emulsions of this invention is not limited to any conventional use. It may be at a certain level. Furthermore, it is also possible to incorporate hardeners into the processing liquid, which is particularly relevant to the processing of radiographic materials, as described for example in Research Disclosure, Vol. 184, 1979, 8.
May, Item 18431, Section K. Typical compound hardeners (pre-hardeners) are researched and
Disclosure, Volume 176, December 1978, Item 17643, Section. Research Disclosure, Volume 176, 1978
By incorporating stabilizers, antifoggants, antikinks, latent image stabilizers and similar additives into the emulsion and adjacent layers prior to coating, as described in December 2013, Item 17643, The minimum density (i.e., fog) in a type emulsion coating can be increased, or the minimum density can be increased or the maximum density can be reduced in a direct positive emulsion coating. C.
EK Mees, The Theory of the
As described in The Photographic Process, 2nd edition, Macmillan, 1954, pp. 677-680.
Many of the antifoggants that are effective in emulsions can also be incorporated into developers and can be classified under a few general headings. In addition to sensitizers, hardeners, and antifoggants and stabilizers, various other commonly used photographic additives may be present. The specific selection of additives to be used depends on the characteristics of the photographic application field.
This can be easily achieved by those skilled in the art. Various useful additives are described in Research Disclosure, Vol. 176,
Listed in December 1978, Item 17643.
As described in ibid. Item 17643, para.
A fluorescent brightener can be added. Absorbing and scattering materials can also be used in separate layers of emulsions and photographic elements according to the present invention, as described in that document. Coating aids as described in Section XI and plasticizing and lubricating agents as described in Section XII may also be present. An antistatic layer may be present as described in Section 1. Methods for adding additives are described in Section 1. A matting agent can be added as described in Section 1. If desired,
Developers and development modifiers can be formulated as described in Sections and Sections XI. When photographic elements containing emulsions according to the invention are utilized in the radiographic field, emulsions and other layers of radiographic elements are specifically described in Research Disclosure, Item 18431, which is incorporated by reference above. It can be in any form. Emulsions of this invention as well as other commonly used silver halide emulsion layers, interlayers, overcoats, and subbing layers, if present in photographic elements, should be researched.
It can be coated and dried as described in Disclosure, Volume 176, December 1978, Item 17643. Properties required for a particular emulsion layer can be obtained by blending the high aspect ratio tabular grain emulsions of the present invention with each other or with conventionally used emulsions in accordance with established practice among those skilled in the art. can be satisfied. For example, by blending multiple emulsions, the characteristic curve of a photographic element can be tailored to meet a given objective.
By blending, increasing or decreasing the maximum density achieved by exposure and processing, decreasing or increasing the minimum density, and adjusting the shape of the characteristic curve between toe and shoulder. I can do it. For this purpose, the emulsion according to the present invention was published in the above-mentioned Research Disclosure, Volume 176, December 1978, as an item.
It can be blended with conventional silver halide emulsions such as those described in Section 17643. Photographic elements according to the invention, in their simplest form, include a single emulsion layer containing a high aspect ratio tabular grain silver halide emulsion according to the invention and a photographic support. Of course, more than one silver halide emulsion layer as well as overcoats, subbing layers and interlayers can be included. Instead of blending the emulsions as described above, a similar effect can be achieved by coating the emulsions to be blended as separate layers. Coating the emulsion layers separately to obtain exposure latitude is well known in the photographic art and is described by Zelikman and Levi, Making.
and Coating Photographic Emulsions Focal Press, 1964,
pp. 234-238, US Patent No. 3,663,228 and British Patent No. 923,045. Additionally, it is well known in the photographic art that photographic speed can be increased by coating fast and slow silver halide emulsions in separate layers rather than blending them. Usually, a high-speed emulsion layer is coated closer to the exposure source than a lower-speed emulsion layer. This technique can be applied to the preparation of three or more stacked emulsion layers. Such a layer configuration can also be utilized in implementing the emulsion according to the present invention. The layers of the photographic element can be coated onto a variety of supports. Typical photographic supports include polymeric films, wood fibers (e.g. paper), metal sheets and foils, glass and ceramic support elements, which depend on the adhesive properties of the support surface,
One or more subbing layers may be formed to improve antistatic properties, dimensional stability, abrasion resistance, hardness, friction properties, antihalation properties, and/or other properties. These supports are well known in the art and are described, for example, in Research Disclosure, Volume 176, December 1978, Item 17643. The emulsion layer or layers are usually coated as a continuous layer on a support having opposing planar major surfaces, but this need not be the case.
The emulsion layer can be coated as a plurality of laterally displaced layer segments onto a flat support surface. When one or more emulsion layers are used as segments, it is desirable to use a microporous support. Useful microporous supports are described in PCT Application Publication No.
W080/01614 (published August 7, 1980; corresponds to Belgian Patent No. 881513, August 1, 1980) and US Pat. No. 4,307,165. The size of the micropores is 1 to 200 micrometers in width and depth.
It can be less than 1000 micrometers.
Generally, in the field of normal black and white photography, especially when enlarging photographic images, the size of the micropores is preferably at least 4 micrometers wide and less than 200 micrometers deep, with the best size being both width and depth. Also 10 to 100 micrometers. Photographic elements employing the emulsions of this invention can be imagewise exposed by any conventional method. See Research Disclosure, Item 17643, supra. The present invention is particularly useful when imagewise exposure is carried out using electromagnetic radiation in the spectral region where the spectral sensitizer present exhibits maximum absorption. If blue, green, red or infrared exposures are to be recorded in the photographic element, a spectral sensitizer is present which absorbs in the blue, green, red or infrared portion of the spectrum. In the field of black and white images, it is desirable to orthochromatically or panchromatically sensitize photographic elements to extend sensitivity within the visible spectrum. The radiation used for exposure produced by a laser can be either incoherent (random phase) or coherent (in phase). high or low intensity exposures, intermittent or continuous exposures, exposure times over relatively short periods of minutes to milliseconds to microseconds, and solarization exposures at normal, elevated or low temperatures and/or at normal, elevated or low pressures. Both image exposure
T.H. James, The Theory of the Photographic Process, No. 4
Edition, Macmillan, 1977, Chapters 4, 6, 17, 18 and 23, within the range of useful sensitivities determined by conventional sentimentary techniques. The photosensitive silver halide contained in the photographic element is prepared in the conventional manner by combining the silver halide with an aqueous alkaline medium in the presence of an alkaline medium or developer contained in the photographic element following exposure to light. It can therefore be processed to form a visible image. Once the silver image has been formed in the photographic element, it is common practice to fix the undeveloped silver halide. The high aspect ratio tabular grain emulsion according to the present invention is particularly advantageous in that fixing can be completed in a shorter time. This allows accelerated processing. The photographic elements and techniques described above for producing silver images can be readily applied to producing color images using dyes. In perhaps the simplest technique for obtaining projectable color images, conventional dyes can be incorporated into the support of the photographic element and formation of the silver image can be carried out as described above. In the areas where the silver image is formed, the photographic element becomes substantially opaque to light, and in other areas, corresponding to the color of the support, it transmits light. Color images can be easily formed in this way. This same effect can also be achieved by using a separate dye filter layer or an element with a dye filter element and a transparent support element. Silver halide photographic elements can be used to form dye images by selective destruction or formation of dyes. The photographic elements for forming the silver image described above are found in Research Disclosure, Volume 176,
It can be used to form dye images by using a developer containing a dye image-forming agent such as a color coupler, as described in December 1978, Item 17643, Section D. In such a form, the developer includes a color developer (e.g., a primary aromatic amine) that, in its oxidized form, is capable of reacting (coupling) with the coupler to form a dye image. Dye-forming couplers can also be incorporated into photographic elements according to conventional methods. Dye-forming couplers can be incorporated in different amounts to achieve different photographic effects. For example, the concentration of coupler with respect to silver coverage can be limited to less than the amounts normally used in fast and intermediate speed emulsion layers. Dye-forming couplers are usually chosen to form subtractive primary color (ie, yellow, magenta and cyan) image dyes, and these couplers are non-diffusible colorless couplers. Dye-forming couplers with different reaction rates in single or multiple separate layers can be used to achieve the desired effect in a particular photographic application. Dye-forming couplers, by coupling, can be used as development inhibitors or accelerators, bleach accelerators, developers, silver halide solvents, toners, hardeners, fogging agents, antifoggants, competitive couplers, chemical or spectral sensitization. releases photographically useful fragments such as agents and desensitizers. Development inhibitor releasing (DIR) couplers are well known in the photographic art. They are,
Non-dye-forming compounds that release various photographically useful groups upon coupling, as well as dye-forming couplers, as described in US Pat. No. 4,248,962. DIR compounds that do not form dyes when reacted with oxidizing color developers can also be used. Additionally, oxidatively cleavable DIR compounds can be used. Relatively insensitive silver halide emulsions, such as Lippmann emulsions, were utilized as interlayers and overcoat layers to prevent or inhibit migration of development inhibitor fragments. The photographic element can be incorporated with coloring dye-forming couplers and/or competing couplers, such as colored dye-forming couplers used to form layered masks for negative color images. The photographic element can further include image dye stabilizers. These are all described in Research Disclosure, Volume 176, December 1978, Item 17643, Section. A dye image can be formed or amplified by employing a method using an oxidizing agent in the form of an inert transition metal ion complex and/or a peroxide oxidizing agent in combination with a dye image-forming reducing agent. can. Photographic elements are particularly suited for forming dye images. Dye images can be formed in photographic elements by selective destruction of dyes or dye precursors, such as silver-dye-bleach techniques. Removal of developable silver by bleaching is common practice in the art of forming dye images in silver halide photographic elements. Removal of such silver can be facilitated by incorporating bleach accelerators or precursors thereof into processing solutions or certain layers of the photographic element. In some cases, especially when amplifying dye images as described above, the amount of silver formed by development is small compared to the amount of dye produced. Silver bleaching is therefore omitted with virtually no visible effect. In still other applications, a silver image is retained and a dye image is utilized to enhance or supplement the density provided by the silver image. When increasing the density of a silver image with dyes, it is usually desirable to use a single neutral dye or a combination of dyes that can produce an overall neutral image. The products of this invention can be used to produce multicolor photographic images. Any conventional multicolor image element, generally containing at least one silver halide emulsion layer, can be improved simply by the addition or replacement of a high aspect ratio tabular grain emulsion according to the invention. The present invention is applicable to both additive and subtractive polychromatic images. First, to describe the application of the present invention to additive polychromatic images, a filter device containing internally disposed blue, green and red filter elements is used in combination with a photographic element containing an emulsion according to the present invention capable of producing a silver image. Can be used. The high aspect ratio tabular grain emulsions of this invention, which are panchromatically exposed and form one layer of a photographic element, are imagewise exposed through an additive primary filter system. When processed to produce a silver image and viewed through a filter device, a polychromatic image is seen. Such images are best viewed by projection. Therefore, both the photographic element and the filter device possess or share a transparent support. Application of the emulsions of this invention in multicolor photographic elements that produce multicolor images through the combination of subtractive primary image-forming dyes can provide particular advantages. Such photographic elements consist of a support and usually at least three sets of overlapping silver halide emulsion layers that separately record blue, green, and red light as yellow, magenta, and cyan dye images, respectively. Although only one high aspect ratio tabular grain silver chloride emulsion as described above is required, multicolor photographic elements contain at least three separate emulsions, each for recording blue, green, and red light. . The emulsions, other than the required high aspect ratio tabular grain green or red recording emulsions, may be in any conventional form. A variety of conventional emulsions are described in Research Disclosure, Item 17643, supra. If more than one emulsion layer is provided to record the blue, green and/or red portions of the spectrum, at least the more sensitive disruptor layer may contain a high aspect ratio tabular grain emulsion such as those described above. It is preferable to include. Of course, it has been found advantageous for all of the blue, green and red recording emulsion layers of a photographic element to be comprised of tabular grain emulsions, if desired. Multicolor photographic elements are often described in terms of color-forming layer units. The most common multicolor photographic elements contain three overlapping color-forming layer units, each capable of recording a different third of the spectrum, and each capable of recording complementary subtractive and primary color dye images. at least one silver halide emulsion layer that can be produced. That is, blue, green and red recording color forming layer units are used to produce yellow, magenta and cyan dye images, respectively. The dye image-forming material does not necessarily have to be present in any color-forming layer unit and can be supplied entirely from the processing solution. When the dye image-forming materials are provided in the photographic element, they may be located in one emulsion layer or in a layer located to receive oxidizing development or electron transfer agents from adjacent emulsion layers of the same color-forming layer unit. can be placed inside. Scavengers are commonly used to prevent color degradation due to migration of oxidizing developer or electron transfer agents between color-forming layer units.
Scavengers can be located within the emulsion layer itself, as taught in U.S. Pat. No. 2,937,086, and/or in intermediate layers between adjacent color-forming layer units, as described in U.S. Pat. No. 2,336,327. It can also be placed in Although each color forming layer unit can include a single emulsion layer, there are often two, three or more emulsion layers in a single color forming layer unit.
Emulsion layers with different photographic speeds are provided. If the desired layer configuration does not permit multiple multicolor emulsion layers of differing sensitivities to be arranged in a single color-forming layer unit, multiple (usually two or three) emulsion layers may be used in a single photographic element.
It is common to provide blue, green and/or red recording color forming layer units. The multicolor photographic element may be in any conventional form so long as it meets the above requirements. Gorokhovskii, Spectral Studies of the Photographic Process,
Focal Press, New York, p.211, table
Any of the six possible layer arrangements described in 27a can be employed. To explain simply and clearly, in the process of preparing conventional multicolor silver halide photographic elements, such photographic elements are sensitive to the negative blue portion of the spectrum and exposed to radiation prior to other emulsion layers. 1 or 2 to receive
A high aspect ratio tabular grain emulsion layer as described above can be provided. In most cases, it will be desirable to replace the conventional minus blue recording emulsion layer with one or more high aspect ratio tabular grain minus blue recording emulsion layers, with modifications to the layer arrangement as necessary. Other layer arrangements will become clearer with reference to the preferred examples below.

【table】

【table】

[Table] In the above, BG and R represent the conventional type of blue, green, and red recording color forming layer units, respectively, and T in front of the color forming layer unit BG or R indicates that the emulsion layer is It indicates that it contains a high aspect ratio tabular grain silver chloride emulsion as described in more detail, and the color-forming layer unit.
F before BG or R indicates that the color-forming layer unit has a higher photographic sensitivity than at least one other color-forming layer unit recording exposures in the same third of the spectrum in the same layer arrangement. color-forming layer unit B.
G. or S before R indicates that the color-forming layer unit has a lower photographic sensitivity than at least one other color-forming layer unit recording exposures in the same third of the spectrum in the same layer sequence. and IL indicates an intermediate layer containing a scavenger but substantially free of yellow filter material. The fast or slow color-forming layer units each occupy an identical third of the spectrum due to the position they occupy in the layer arrangement.
Other color-forming units that record exposures can differ in their photographic sensitivity, inherent sensitivity characteristics, or a combination of both. In the layer arrangement, the position of the support is not indicated. According to convention, the support is almost always located at a location farthest from the source of exposing radiation;
That is, it will be below the indicated layer. If the support is colorless and specular, i.e. transparent, then
It may be between the exposure source and the indicated layer. More generally, the support can be interposed between the exposure source and the color-forming layer unit for recording light to which the support is transparent. Photographic emulsions for forming multicolor images consisting of subtractive combinations of primary color dyes usually take the form of multiple superimposed layers containing dye-forming materials such as incorporated dye-forming couplers. is no longer necessary. There are three color-forming components, usually called packets, each containing a silver halide emulsion for recording light in one-third of the visible spectrum and a coupler capable of forming complementary subtractive primary color dyes. They can be put together in a single layer photographic element to produce multicolor images. Typical mixed packet multicolor photographic elements are disclosed in U.S. Pat. Nos. 2,698,794 and 2,843,489. The high aspect ratio tabular silver chloride emulsion of the present invention is
This is advantageous due to less high angle light scattering compared to non-tabular and low aspect ratio tabular grain emulsions. This can be shown quantitatively. In FIG. 5, a sample of emulsion 1 according to the present invention is shown.
It is coated on a transparent (specular) support 3 at a silver coverage of 1.08 g/m ² . Although not shown, the emulsion and support are provided with a
Preferably, it is immersed in a liquid having substantially balanced refractive indices. The emulsion layer is exposed by a parallel light source 5 at right angles to the plane of the support. Light from a light source following the path indicated by point 7 forming the optical axis strikes the emulsion layer at point A. The light passing through the support and emulsion layer is detected at a hemispherical detection surface 9.
It can be detected at a certain distance from the emulsion. A maximum intensity level of light is detected at point B, which is at the intersection of the initial optical path extension and the detection surface. An arbitrarily selected point C is shown on the detection surface in FIG. The dotted line between A and C forms an angle φ with respect to the emulsion layer, and by moving point C on the detection surface, φ can be varied from 0 to 90°. By measuring the intensity of the scattered light as a function of the angle φ, the cumulative light distribution can be determined as a function of the angle φ (this is because the light scattering around the optical axis 7 is rotationally symmetric). Background descriptions of cumulative light scattering include DePalma and Gasper;
“Determining the Optical Properties of Photographic Emulsions by Monte Carlo Method”
Photographic Emulsions by the Monte Carlo
Method)”, Photographic Science
and Engineering, Vol. 16, No. 3, May-June 1971, pp. 181-191. After determining the cumulative light distribution as a function of the angle φ at values between 0 and 90° for the emulsion 1 according to the invention, a normal The same operation was repeated using an emulsion. In comparing the cumulative light distribution as a function of angle φ for values of φ up to 70° (and in some cases up to 80° and above) for the two emulsions, the amount of scattered light is There are fewer. Therefore, the high aspect ratio tabular grain emulsions of this invention exhibit lower high angle scattering. Since high-angle light scattering causes undue reduction in image sharpness, the high aspect ratio tabular grain emulsions of the present invention in each case
This makes it possible to provide sharper images. In FIG. 5, angle θ is shown as complementary to angle φ. As defined herein, the term "collection angle" means that half of the light striking the detection surface is within the region defined by the cone formed by rotating line AC through an angle θ about its polar axis. , on the other hand, the value of the angle θ is such that half of the light hitting the detection surface hits the detection surface other than the remaining area. Although it is not intended to explain the reduced high-angle scattering properties of the high aspect ratio tabular grain emulsions of the present invention by any particular theory, it is clear that the large flat main crystals provided by the high aspect ratio tabular grains are It is believed that the orientation of the particles in the surface as well as in the coating layer provides an improvement in the observed sharpness. In particular, it has been observed that the tabular grains present in the silver halide emulsion layer are substantially parallel to the flat support surface on which the grains are placed. Thus, light directed perpendicular to the photographic element that impinges on the emulsion layer will impinge on the tabular grains substantially perpendicular to one major crystal face. The thinness of the tabular grains as well as their orientation when coated allows the high aspect ratio tabular grain emulsion layers of this invention to be substantially thinner than conventional emulsion layers, which also improves sharpness. can be given. However, the emulsion layers of this invention also exhibit improved sharpness when they are coated to the same thickness as conventional emulsion layers. In certain preferred embodiments of this invention, the high aspect ratio tabular emulsion layer is at least 1.0 micrometers, and preferably at least 2
Indicates the minimum average particle diameter in micrometers. Improved sensitivity and sharpness are both achievable as the average particle size is increased. Although the maximum effective average grain size will vary with the granularity that can be tolerated for a particular imaging application, the maximum average grain size of the high aspect ratio tabular grain emulsions of this invention is in all cases 30 microns. , preferably smaller than 10 microns, optimally larger than 10 microns. Although it is possible to obtain reduced high-angle scattering with single layer coatings of high aspect ratio tabular emulsions according to the present invention, reduced high-angle scattering is not necessarily achieved in multicolor coatings. . In certain multicolor coating formats, increased sharpness can be achieved with the high aspect ratio tabular grain emulsions of this invention. However, in other multicolor coating formats, the high aspect ratio tabular grain emulsions of this invention can actually reduce the sharpness of the underlying emulsion layer. Looking back at the layer arrangement, it can be seen that the blue recording emulsion layer is closest to the exposing radiation source, while the underlying green recording emulsion layer is the tabular grain according to the invention. This green recording emulsion layer, on the other hand, overlies the red recording emulsion layer. If the blue recording emulsion layer contains grains with average diameters in the range 0.2 to 0.6 micrometers, as is common in many non-tabular emulsions, the maximum amount of light passing through it and reaching the green and red recording emulsion layers is It will show scattering. If the light is unlucky enough to be scattered before it reaches the high aspect ratio tabular grain emulsion that forms the green recording emulsion layer, the tabular grains allow more light to pass through and reach the red recording emulsion layer than the normal emulsion. It may scatter to even higher extents. Therefore, the particular choice of emulsion and layer arrangement reduces the sharpness of the red recording emulsion layer to a greater degree than if the emulsion according to the invention were not present in the layer arrangement. become. In order to fully realize the sharpness benefits in the emulsion layers underlying the high aspect ratio tabular grain silver chloride emulsion layers of the present invention, the tabular emulsion layers must be positioned to receive light without appreciable scattering. It is preferable to let In other words, improvements in sharpness in emulsion layers underlying tabular grain emulsion layers are best realized only when the tabular grain emulsion layers are not themselves underlying turbid layers. For example, if a high aspect ratio tabular grain green recording emulsion layer is above the red recording emulsion layer and below the Lippmann emulsion layer and/or the high aspect ratio tabular grain blue recording emulsion layer of the present invention, The sharpness of the red recording emulsion layer may be improved by the presence of the overlying tabular grain emulsion layer. Quantitatively, an improvement in the sharpness of the red recording emulsion layer is obtained if the angle of gathering above the high aspect ratio tabular grain green recording emulsion layer is less than about 10°. Of course, it is immaterial whether the red recording emulsion layer itself is a high aspect ratio tabular grain emulsion layer according to this invention, as far as its influence on the sharpness of the overlying layer is concerned. In multicolor photographic elements containing superimposed color-forming units, it is preferred for sharpness advantages that at least the emulsion layer closest to the source of exposing radiation be a high aspect ratio tabular grain emulsion. . In particularly preferred embodiments, each emulsion layer that is closer to the exposing radiation source than the other image-recording emulsion layers is a high aspect ratio tabular grain emulsion layer. The layer ranking arrangement mentioned above,
, , and are examples of multicolor photographic element layer arrangements that can clearly increase the sharpness of the underlying emulsion layers. Although the advantageous effects of high aspect ratio tabular grain silver chloride grains on image sharpness in multicolor photographic elements have been specifically described with respect to multicolor photographic elements, the sharpness advantages are important in multilayer black and white photography for forming silver images. It can also be obtained in elements. It is common to divide emulsions that give black and white images into fast and slow layers. By using the high aspect ratio tabular grain emulsions of this invention in the layer closest to the exposing radiation source, the sharpness of the underlying emulsion layer will be improved. (d) Embodiment Examples The invention may be better understood by reference to the following specific examples. In each example, the contents of the reaction vessel were vigorously stirred throughout the introduction of the silver and halide salts. The term "%" means weight percent unless otherwise indicated, the term "N" indicates normality unless otherwise indicated, and all solutions are aqueous unless otherwise indicated. Example 1 Preparation of tabular grain AgCl emulsion at 30°C. 2.0 liters of bone gelatin aqueous solution (2.0% gelatin, 0.001N NH ₄ NO ₃ , solution A) was added to 7.5N ammonium hydroxide aqueous solution (solution D) at 30°C.
was added to adjust the pH to 9.05, and an aqueous bone gelatin solution (4.2% gelatin) containing ammonium chloride (2.01 mol, solution B) was added to adjust the pCl to 1.05. To solution A maintained at 30°C, pH 9.05 and pCl 1.05 (pAg 8.5), solution B and an aqueous solution of silver nitrate (2.00 mol, solution C) were added by double jet addition at a constant flow rate for 5 minutes (total Silver consumption 6.7
%). During the first 5 minutes, double-jet solutions B and C while slowing the flow rate (6 times from start to finish, i.e. 6 times more at the end than at the start).
(approximately 20 minutes, consuming 93.3% of the total silver nitrate used) while holding at pCl 1.05 and 30°C. At the same time, a third jet is used to prepare solution D.
was added at a rate sufficient to maintain the pH at 9.05. 4.5 moles of silver nitrate were used to prepare this emulsion. The tabular grain AgCl emulsion obtained by this operation is shown in FIG. 1 (photograph magnified 1000 times). More than 50% of the projected area of the silver chloride grains is in the form of tabular grains. These tabular grains have a thickness of less than 0.6 micrometers and exhibit an average aspect ratio of about 10:1. Example 2 Preparation of tabular grain AgCl emulsion at 40°C. 1.0 liter of bone gelatin aqueous solution (6% gelatin, 0.1N NH ₄ NO ₃ , solution A) was added at 40°C.
The pH was adjusted to 8.8 by adding a 3.75N aqueous ammonium hydroxide solution (Solution D), and the pCl was adjusted to 1.3 by adding an ammonium chloride (2.00 mol)/ammonium hydroxide (0.2N) aqueous solution (Solution B). 40
Solution B and an aqueous silver nitrate solution (2.00 mol, solution C) were added to solution A maintained at 0.degree. At the same time, Solution D was added to Solution A through a third jet at a rate sufficient to maintain the pH at 8.8. 1.0 mole of silver nitrate was used to prepare this emulsion. The tabular grain AgCl emulsion obtained by this operation is shown in FIG. 2 (photograph magnified 500 times). Tabular silver chloride grains in the emulsion of FIG. 2 are present in a higher proportion (greater than 50% projected area) than in FIG. The average aspect ratio of these tabular grains is about 10:1. Example 3 Preparation of tabular grain AgCl emulsion at 60°C. 1.0 liter of bone gelatin in water (80% gelatin, solution A) was added with 7.5N ammonium hydroxide in water (solution D) to a pH of 8.8, and ammonium chloride (2.00 mol)/ammonium hydroxide (0.2N). Add aqueous solution (solution B) to bring the pCl to 1.3
(pAg7.3). Solution B and silver nitrate aqueous solution (2.00
mol of solution C) at a constant flow rate through a double jet until solution C runs out (approximately 25 minutes).
Added. At the same time, solution D was added to solution A at a rate sufficient to maintain the PH at 8.8. 1.0 mole of silver nitrate was used to prepare this emulsion. The tabular grain AgCl emulsion obtained by this operation is shown in FIG. 3 (photograph magnified 250 times). In FIG. 3, more than 75% of the total projected area of silver chloride grains is occupied by tabular grains. These tabular silver chloride grains have an average aspect ratio greater than 10:1. Example 4 (Comparative) Preparation of a tabular grain AgCl emulsion from 3×10 ⁻⁸ m (300 Å) diameter Ag seed grains. 1.0 liter of bone gelatin aqueous solution (6.0% gelatin, 0.1N NH ₄ NO ₃ , solution A) was adjusted to pH by adding 3.75N ammonium hydroxide aqueous solution (solution D).
8.8 and ammonium chloride (2.00 mol)/
Ammonium hydroxide (0.2N) aqueous solution (solution B)
and the addition of Ag seed particles (6.25 × 10 ^-4 mol) with a diameter of 3 × 10 ^-8 m (300 Å) to reduce the pCl to 1.3.
(pAg7.9). Solution B and an aqueous solution of silver nitrate (2.00 mol, solution C) were added to solution A maintained at 40 DEG C. and pCl 1.3 at a constant flow rate by double jet until solution C was gone (approximately 25 minutes). At the same time, Solution D was added at a rate sufficient to maintain the PH at 8.8 by means of a third jet. This emulsion was prepared using 1.0 moles of silver nitrate. The tabular grain AgCl emulsion obtained in this example is shown in Figure 4 (photograph magnified 500x). The tabular silver iodochloride grains of FIG. 4 have smaller dimensions compared to the tabular silver iodochloride grains of FIG. 2 produced at the same temperature. Also, the proportion of non-tabular grains in FIG. 4 is greater than in FIG. Example 5 Same as Example 2 except that 3.0 liters of 4.0% gelatin solution was used, the processing time was 16 minutes, 7.5 moles of ammonium hydroxide was used to maintain the pH, and a total of 3 moles of emulsion was precipitated. A tabular grain AgCl emulsion was prepared by repeating the same operation as above. After precipitation, 1.0 liter of an aqueous gelatin solution (12.0% by weight) was added and the emulsion was prepared according to the method of Yutzy and Russell, US Pat.
Cleaned by the coagulation process of No. 2614929. Then 45g of bone gelatin was added and the emulsion was adjusted to pH 5.6 and pAg 7.5 at 40°C. The resulting AgCl emulsion had an average tabular grain size of 6.3 μm, an average tabular grain thickness of 0.65 μm, and an average aspect ratio of 9.7:1, with more than 58% of the projected area occupied by tabular grains. . The emulsion was chemically sensitized with 15 mg of gold sulfide per mole of silver and then deposited on a cellulose triacetate film support at 4.3 g per square meter.
of silver and 12.9 g of gelatin per square meter. The coated layer was exposed to a 600W, 2850㎓ tungsten light source for 1 second through a 0-4.0 density continuous doublet and then incubated at 20°C in an N-methyl-p-aminophenolsulfate (Elon)-ascorbic acid surface developer. It was treated for 6 minutes. Sensitometry results are D _nio 0.10, D _nax 0.90
and gave a clear negative image with a contrast of 0.58. (e) Effects and Advantages of the Invention The radiation-sensitive silver halide photographic emulsions of the present invention provide increased sharpness when incorporated into multilayer photographic elements, and when optically and chemically and spectrally sensitized, produces a good sensitivity-granularity relationship and increases sensitivity between the spectrally sensitized region of the spectrum and the ultraviolet region of the spectrum when blue, green, and/or red sensitized and oriented in a photographic element can show the separation that has occurred. Prior to this invention, there was a need for photographic emulsions that offered the particular advantages of both silver chloride aspect ratio and grain morphology, ie, greater than 8:1. The present invention satisfies this need. The silver chloride emulsion of this invention is
Other photographic advantages such as higher maximum density and higher covering power can be provided. Depending on the particular photographic application, other photographic advantages may also be provided. The present invention also proposes advantageous methods for producing relatively high aspect ratio silver halide grains that are internally free of silver iodide and bromide. The precipitation process does not require the use of cadmium dopants or organic particle growth modifiers to establish particle morphology. Although not compatible with the practice of this invention, it is not necessary to provide seed crystals or to vary precipitation conditions to obtain high aspect ratio grains during the nucleation and growth stages of emulsion precipitation. In a preferred embodiment of the invention, the precipitation process of the invention comprises:
It is therefore operationally simpler than prior art processes for obtaining high aspect ratio silver halide grains.

[Brief explanation of the drawing]

Figures 1, 2, 3 and 4 are micrographs of silver halide emulsions. FIG. 5 is a schematic diagram for explaining the concept regarding scattering of exposure radiation. 1... Emulsion, 3... Support, 5... Parallel light source,
9...Detection surface.

Claims (1)

[Scope of Claims] 1 A particle comprising a dispersion medium and silver chloride particles, wherein at least 50% of the total projected area of the silver chloride particles does not contain bromide and iodide internally and has an average aspect ratio of greater than 8:1. 1. A radiation-sensitive silver halide photographic emulsion characterized in that it is dominated by tabular grains having a symmetrical ratio and having opposing parallel {111} major crystal faces. 2 comprising a dispersion medium and silver chloride grains, at least 50% of the total projected area of the silver chloride grains does not contain bromide or iodide therein, and has an average aspect ratio greater than 8:1; A radiation-sensitive silver halide photographic emulsion comprised of tabular grains with opposing parallel {111} major crystal faces is prepared by adding chloride and silver salt solutions simultaneously into a dispersion medium in the presence of ammonia by the double-jet method. A method for manufacturing by introducing
Maintain pAg in the range of 6.5 to 10 and PH of dispersion medium to 8.
A method characterized by holding in the range of ~10.