JPH09120109A - Radiographic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photographic element using starch as a deflocculant. SOLUTION: This photographic element consists of a transparent film base body and a first emulsion layer unit and a second emulsion layer unit applied on the surfaces of the supporting body opposite to each other. Each of the emulsion layer unit contains at least one kind of a radiation-sensitive emulsion containing silver halide particles, a sensitizing dye adsorbing to the surface of the silver halide particles, a binder for the silver halide particles and a hydrophilic colloid vehicle which acts as a deflocculant. The silver halide particles has >50mol% bromide content and <4mol% iodide content based on the amt. of silver and includes planer particles having 111} principal plane by >50% area of the total projection area of particles. The part of the vehicle which acts at least as a deflocculant is hydrophilic colloid produced from water- dispersible cationic starch.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improvements in radiographic elements. More specifically, the present invention relates to a high bromide {1
11} Radiographic elements using tabular grain silver halide emulsions. The term "radiographic element" means an X-ray pattern recording element. These include indirect radiographic elements that use an intensifying screen to absorb X-rays and emit a corresponding light pattern for recording on the radiographic element.

The term "double-sided coating" means a radiographic element containing an image recording unit on each side of the x-ray transparent support facing away from it. Thus, dual-coated radiographic elements are quite different from "double-coated" or "triple-coated" photographic elements which contain multiple silver halide emulsion layers on only one side of the support. The term "equivalent circular diameter" or "ECD" is used to indicate the diameter of a circle that has the same projected area as a silver halide grain.

The term "aspect ratio" means the ratio of grain ECD to grain thickness (t). The term "flatness"
Is defined as ECD / t ^{2 where} ECD and t are both units of measurement in microns (μm). The term "tabular grain" refers to a grain having two parallel crystal faces that are significantly larger than the remaining crystal faces and an aspect ratio of at least 2.

The term "tabular grain emulsion" means an emulsion in which tabular grains account for greater than 50 percent of total grain projected area. The term "high bromide" in relation to grains and emulsions indicates that bromide is present in a concentration of greater than 50 mole percent, based on total silver. For grains and emulsions containing more than one halide, the halides are named in order of increasing concentration.

The term "{111} tabular" is used to refer to tabular grains and tabular grain emulsions in which the tabular grains have {111} major faces. The terms "hydrophilic colloid vehicle" and "vehicle" mean the hydrophilic colloid peptizers and binders present in silver halide emulsions. The terms "selected vehicle" and "selected peptizer" are used to indicate a vehicle or peptizer derived from a water dispersible cationic starch.

The term "cation" in relation to starch indicates that the starch molecule has a net positive charge at the pH of its intended use. The term "oxidized" in relation to starch means that, on average, at least one α-D-glucopyranose repeat unit per starch molecule has two ring positions.
Figure 4 shows a starch that has been opened by cleavage of the carbon-carbon bond at positions 3 and 3.

The term "water dispersible" in relation to cationic starch means that after boiling the cationic starch in water for 30 minutes, it causes at least 1.0% by weight of the total cationic starch to reach at least colloidal levels. It indicates that it is dispersed and contained. The term "intermediate chalcogen" refers to sulfur, selenium and / or tellurium.

[0008]

BACKGROUND OF THE INVENTION Radiation-sensitive silver halide emulsions used in radiographic elements are:
It comprises a dispersion medium and silver halide microcrystals commonly referred to as "grains". Precipitation of the particles from the aqueous medium prevents the hydrophilic colloid peptizer from adsorbing on the particle surface and agglomerating the particles. Subsequently, the binder is added to the emulsion, and after coating, the emulsion is dried. The peptizer and binder are collectively referred to as the emulsion vehicle.

Gelatin and gelatin derivatives form the bulk of the remainder of the peptizer and vehicle in the overwhelming majority of silver halide radiographic elements. For gelatin, see The Theory of by Mees.
From the description of the He Photographic Process, Rev., Macmillan, 1951, pages 48 and 49: "Gelatin is a substance with a remarkable history; its nature and its future trends are Gelatin is very similar to glue, at the beginning of the AD, Plin
Y wrote, "The glue is made from bull skin." This is described equally easily by today's authors as "a dry soup or consomme of some animal waste." The glue making process has been known for a long time and consists essentially of bovine and porcine skin clippings or boiling bones. The resulting juice is filtered, cooled and solidified into a jelly form. This jelly, when cut and dried on a net, becomes a glue sheet or gelatin sheet, depending on the raw materials and manufacturing method selected. In the production of glue, the extraction is continued until the final yield is obtained from the material; in the case of gelatin, the extraction is stopped earlier and is carried out at a lower temperature, so that gelatin has the specific strength of glue. There are no components that are adhesive but non-jellifying. Thus, glue is distinguished by its adhesiveness; gelatin is distinguished by its cohesiveness, which favors the formation of strong jellies.

Photographic gelatin is generally manufactured from cheek strips and pastes as well as selected calf hides and ears. Pig skin is used in the manufacture of certain gelatins, and larger quantities are made from bone. The substance of the skin that actually provides gelatin is collagen. Collagen
It constitutes about 35% of the dermis of fresh calf hide. The corresponding tissue obtained from the bone is called bone quality. Raw materials are selected not only for good structural quality, but also for the absence of bacterial degradation. In the preparatory stage of extraction, loose meat and debris with blood are washed out beforehand. Hair, fat and large amounts of albuminous substances are removed by immersing the raw material in lime water containing suspended lime. Free lime continues to show a rejuvenating effect on the solution, keeping the bath at a suitable alkalinity.
After this operation, gelatin is extracted by decalcification with dilute acid, washing and boiling. Several "boilers" were prepared with increasing temperature and usually the last extraction product is not used in photographic gelatin. The crude gelatin solution is filtered, concentrated if necessary, cooled to set, divided and dried to flakes. The residue after gelatin extraction is mainly composed of elastin and reticuline, and contains some keratin and albumin.

Gelatin may be prepared by acid-treating a raw material without using lime. The raw material is treated with dilute acid (pH 4.0) for 1-2 months, washed thoroughly, and gelatin is extracted. This gelatin has different properties from gelatin produced by lime treatment. In addition to collagen and ossein, which are to be extracted in the production of gelatin, other substances are naturally involved. For example, J
by Ames, The Theory of the P
photographic Process, 4th edition, M
Acmillan, 1977, p. 51, describes: "Collagen is generally the major protein component in tissue, but is always a non-collagen protein, mucopolysaccharide, polynucleic acid and lipid. Are associated with various "substrates" such as. For the production of photographic gelatin, it is desirable to remove them almost completely. In addition to the complexity of the composition, changes in the composition of the diet of the animals that provide the ingredients also result in composition variations. The most commonly known example of this was ultimately attributed to a reduction in the sulfur content of lots of purchased gelatin, the 1882 Eastman Dry Plate Company.
Is a forced suspension produced by.

Given the time, effort, complexity and cost involved in gelatin production, it is surprising that past research efforts have been directed at replacing gelatin used in photographic emulsions and other film layers. is not. However, by 1970, the desperate hope of finding a generally acceptable alternative to gelatin was abandoned. A number of alternative substances were identified as useful as peptizers, but all were found to a limited extent. Of these, cellulosics are clearly the most commonly known, but their use is limited because of the insolubility of cellulosic materials and the denaturation required to be effective in peptization. ing.

Research Disclosure
e, Volume 365, September 1994, Item 3654.
4, Section II, "Vehicles, vehicle extenders, vehicle-like additives and vehicle-related additives, A. Gelatin and hydrophilic colloid peptizers (Vehicles, ve)
single extenders, vehicle-1
ike addenda and vehicle r
elated addenda, A .; Gelatin
and hydrophilic colloid
Peptizers), paragraph (1) has the following description: "(1) The photographic silver halide emulsion layers and other layers on the photographic element can contain various colloids, alone or in combination, as vehicles. Such hydrophilic substances include natural substances such as proteins, protein derivatives, cellulose derivatives such as cellulose esters,
Gelatin, for example, alkali-treated gelatin (porcine skin gelatin), gelatin derivative, for example, acetylated gelatin, phthalated gelatin, etc., polysaccharides, for example, dextran, gum arabic, zein, casein, pectin, collagen derivative, collodion, agar- There are agar, arrowroot, albumin, etc. This description is for Research Disclosure
e, Volume 176, December 1978, Item 1764.
3, section IX. "Vehicles and vehicle ext
enders) ", paragraph A. Research Disclosure
Kenneth Mason Publicatic at Dudley House, North Street, Emsworth 12 Hampshire P010 7DQ, United Kingdom
Published by ons.

In the 1980's there were significant advances in radiographic elements containing silver halide emulsions. U.S. Pat. No. 4,425,425 (Abbott et al.) Disclosed reduced crossover in double coated radiographic elements using spectrally sensitized high (> 8) aspect ratio tabular grain emulsions. U.S. Pat. No. 4,425,426 (Abbo
tt et al.) extended these considerations to radiographic elements using thin (<0.2 μm) intermediate (5-8) aspect ratio tabular grain emulsions. U.S. Pat. No. 4,414,30
No. 4 (Dickerson et al.) Was derived from the consideration that, unlike emulsions conventionally used in radiographic elements, tabular grain emulsions exhibit high covering power characteristics with minimal effect of increased hardening of the emulsion vehicle. Discloses a radiographic element containing a fully precured tabular grain emulsion. Based on these advantages of dual-coated radiographic elements, conversion to tabular grain emulsions has occurred in industry.

Abbott et al. And Dicker described above
Son's description of high bromide {111} tabular grain emulsions incorporates the vehicle disclosure of Research Disclosure, Item 17643, in the exact same terms. Only gelatino-peptizers are actually shown in the examples. Despite the assumption that the choice of normal vehicle is still adequate for tabular grain emulsions, some confirmation was made that the choice of certain peptizers was particularly advantageous for tabular grain emulsions. . U.S. Pat. No. 4,40
0,463 (Maskasky) disclosed combining synthetic peptizers with adenine to produce high (> 50 mole%) chloride tabular grain emulsions. Later, U.S. Pat. Nos. 4,713,320 and 4,713,323 (Maskasky) showed that high bromide and high chloride tabular grain emulsions could be improved by treating gelatin with an oxidizing agent. .

US Pat. No. 5,284,744 (Mas
Kasky) teaches the use of potato starch as a deflocculant in the preparation of cubic grain silver halide emulsions, showing that potato starch has a low absorption in the wavelength range 200-400 nm compared to gelatin. It was Maskasky (US Pat. No. 5,284,74
No. 4) does not disclose tabular grain emulsions.

Despite the advances made in the industry to enable tabular grain emulsions in double coated radiographic elements, some are unique to double coated radiographic elements and some are halogen. There remains a problem that is common to all elements using silver halide emulsions. While some of these problems have been desperately pursued to find a solution, other problems have received little attention recently and have been taken as an inevitable limitation of silver halide emulsions.

It has been found advantageous for silver halide emulsions for photographic use to reduce tabular grain thicknesses to the lowest levels that can be reliably obtained. Therefore, recent interest has been directed to ultrathin (thickness <0.07 μm) tabular grain emulsions. In radiographs, the minimum average tabular grain thickness is generally about 0.1 μm. The thicker tabular grains in the radiograph are dictated by the warmer images that occur as the tabular grain thickness decreases. In medical diagnostic imaging, which is a major application for dual-coated radiographic elements, radiologists
I like "cold" radiography. Thermal imaging has been an obstacle to realizing the benefits of tabular grain emulsions having average grain thicknesses of less than 0.1 µm. Inclusion of ultrathin tabular grains in a dual-coated radiographic element increases the surface-to-volume ratio of the tabular grains, permitting the use of higher levels of spectral sensitizing dye per unit of silver, thereby increasing crossover. Is reduced.

The cost and inconvenience of producing gelatin and gelatin-derived vehicles has generally become acceptable, as no alternatives beyond these have been found despite centuries of research. It was
Conventional peptizers derived from gelatin, cellulose and starch exhibit viscosity levels well above that of water when used as aqueous peptizers in forming silver halide emulsions.

Further, the temperature is lowered to room temperature (nominal 20
(° C), the viscosity increases significantly, which is why
Precipitation of silver halide emulsions typically begins in the temperature range of 30-90 ° C. The elevated viscosity levels imparted by these peptizers hinder the reactant mixing to obtain uniform grain characteristics, even at the elevated temperatures used for silver halide precipitation. For example, high viscosity counteracts uniform mixing on a microscale (micromixing), which is essential for nucleation and growth of uniform particles. The non-uniformity of grain nucleation and, to a lesser extent, the non-uniformity of growth is due to the inclusion of grains with different shape and size and in the case of multiple halide co-precipitation, co-precipitation of grains with different halide internal distributions. Provides polydispersity.

On a macro scale, increasing viscosity levels make it difficult to scale up silver halide precipitation to a volume convenient for manufacturing purposes. As the viscosity level increases, it becomes difficult to continue the desired level of bulk mixing of the reactants as the total volume of the reaction vessel increases. Naturally-derived peptizer polymers contain a mixture of various molecules of different weights and structures, not all of which are well suited for emulsion preparation. Moreover, peptizers undergo changes based on the source of the material, and their composition may change over time, even when obtained from a single commercial source. Undesirable effects may occur in both physical properties such as turbidity and sensitometric properties such as fog.

It is generally accepted that it is necessary to carry out chemical sensitization with any one or a combination of intermediate chalcogens (ie sulfur, selenium and / or tellurium), noble metals (eg gold) or reduction sensitizations. ing. At least about 5 to get maximum acceptable photographic sensitivity everywhere
Heating to 0 ° C. is common and the maximum temperature is limited only by the ambient vapor pressure (eg, complete evaporation of water). At these elevated temperatures grain ripening is accelerated. This can have various undesirable effects depending on the nature of the grains present in the emulsion and the intended end use.
For example, ripening rounded grain edges and corners of non-destructive grains completely removes the smaller grains and destroys useful grain properties (eg, aging leads to undesirable thickening of tabular grains). ). Ultra-thin (thickness <0.07μ, especially sensitive to unwanted aging)
m) Tabular grain emulsions which may exhibit an average grain thickness increase of greater than 30% (and more) when ripening occurs at normal chemical sensitization temperatures. In addition, high temperatures during grain precipitation can accelerate undesirable ripening and can compromise desired grain properties.

Finally, it was found that starch, which has been conventionally investigated as a peptizer, is obviously inferior in peptizing action. Further, the above-mentioned US Pat. No. 5,
Conventional starch peptizers such as those shown in 274,644 (Maskasky) favor the formation of grains having {100} crystal faces, while high bromide tabular grains are practical. It requires a {111} plane in the form which has been found to be suitable.

[0024]

According to one aspect of the present invention, there is provided a transparent film support and a first emulsion layer unit and a second emulsion layer unit coated on opposite sides of the support, respectively. Each of the emulsion layer units (a) has a bromide content of more than 50 mol% and an iodide content of less than 4 mol% based on silver, and the tabular grains having {111} major faces represent the total grain projected area. Silver halide grains accounting for more than 50%, (b) a spectral sensitizing dye adsorbed on the surface of the silver halide grains, and (c) hydrophilic acting as a binder and a peptizer for the silver halide grains. A radiographic element comprising at least one radiation-sensitive emulsion comprising a hydrophilic colloid vehicle, wherein at least the portion of the vehicle that acts as a peptizer is a hydrophilic colloid derived from a water-dispersible cationic starch. Radiographic elements are provided, characterized in that it.

Quite surprisingly, cationic starch is more suitable for producing high bromide {111} tabular grain emulsions than non-cationic starch, and the presence of cationic starch in place of gelatin results in imaging surfaces. It has been found that the advantages of Cationic starch has lower viscosity levels than previously used to make tabular grain emulsions, and oxidation of cationic starch further reduces viscosity. The reduced viscosity facilitates uniform mixing. Both micro-mixing, which controls the particle composition, average particle size and dispersibility, and bulk-mixing, which scales up precipitation to a convenient manufacturing scale, are preferred due to the reduction in viscosity allowed by cationic starch peptizers. to be influenced. Precise control of grain nucleation, including monodispersion of grain nuclei, is particularly important for successfully obtaining tabular grain emulsions and improving their properties.

Higher imaging sensitivities can be achieved with cationic starch under comparable levels of chemical sensitization.
Alternatively, the temperature during chemical sensitization of the cationic starch peptized tabular grain emulsion can be lowered to achieve imaging sensitivities comparable to or better than gelatin peptized emulsions. Reducing the temperature has the advantage of preventing tabular grains from undesired ripening during chemical sensitization.

The oxidized cationic starch allows emulsion precipitation at ambient temperature. Furthermore, oxidized cationic starch generally enables chemical sensitization at a lower temperature than cationic starch. The construction of a dual-coated radiographic element can be understood generally with reference to FIG. FIG. 1 illustrates a dual coated radiographic element 100 according to the present invention as a set of light emission intensifying screens 20.
1 shows the assembly located between 1 and 202. The radiographic element comprises a typically bluish transparent film support 101 capable of transmitting both light and X-rays (exposing the radiographic element). The film support is provided with undercoat layers 103 and 105, if necessary, to facilitate the adhesion of the coating layers. If necessary, crossover-reducing hydrophilic colloid layers 111 and 113 are provided on the first and second main surfaces 107 and 109 of the support formed by the subbing layer, respectively. Emulsion layer units 115 and 117 comprising one or more hydrophilic colloid layers including at least one silver halide emulsion layer are provided on the crossover reducing layer. Optionally, but preferably, hydrophilic colloid protective overcoat layer 119.
And 121 are provided on the emulsion layer unit.

In use, the assembly is imagewise exposed to x-rays. The X-rays are mainly intensifying screens 201 and 202 that promptly emit light directly related to the X-ray exposure dose.
Is absorbed by The light emitted by the screen 201 mainly exposes the emulsion layer units 115, whereas the light emitted by the screen 202 mainly emits the emulsion layer units 11.
7 is exposed. Following imagewise exposure, the radiographic element is separated from the intensifying screen and processed (developed, fixed and washed) to produce a silver image in each of the emulsion layer units.
The two superimposed silver images appear as a single radiographic image when viewed in a transparent light box.

To obtain the highest possible level of imaging performance, each emulsion layer should contain at least one high bromide {11
1} It contains a tabular grain emulsion. To increase light absorption by grains that make up the emulsion and to reduce image sharpness reducing crossover (light transmission from the intensifying screen on one side of the support to the emulsion layer on the other side of the support) Then, at least one spectral sensitizing dye is adsorbed on the grain surface. The optional crossover reduction layer typically contains microcrystalline dye particles to further reduce crossover. Microcrystalline dye particles are selected for decolorization during processing so that the silver image can be viewed by transmission.

A water-permeable hydrophilic colloid vehicle is used for the protective overcoat, emulsion layer and crossover reducing layer so that the processing liquid can penetrate into these layers. In the protective overcoat and crossover reduction layer, the sole function of the vehicle is to act as a binder. In the emulsion layer, the vehicle serves both as a binder to hold the coating together and as a peptizer for the silver halide grains.

The unique features of the radiographic elements of this invention are:
Of the hydrophilic colloids that make up the radiographic element,
At least a portion of the high bromide {111} tabular grain emulsion used as a peptizer is derived from a water-dispersible cationic starch. The term "starch" includes both native starch and modified derivatives such as dextrinized, hydrolyzed, oxidized, alkylated, hydroxyalkylated, acetylated or fractionated starch.

The starch can also be derived from corn starch, wheat starch, potato starch, tapioca starch, sago starch, rice starch, waxy corn starch or high amylose corn starch. Starch generally comprises two structurally distinct polysaccharides, α-amylose and amylopectin. Both comprise α-D-glucopyranose units. In α-amylose, α-D-glucopyranose units form 1,4-long chain polymers. The repeating unit takes the following form:

[0033]

Embedded image

In amylopectin, the repeating unit 1,
In addition to 4-bonding, branching of the chain at the 6-position (-CH ₂ OH above)
The site of the radical) is also apparent, resulting in a branched polymer.
The repeating units of starch and cellulose are diastereoisomers that impart different overall geometries to the molecule.
The α-anomers found in starch and represented by formula I above are polymers capable of crystallizing and having some degree of hydrogen bonding between repeating units in adjacent molecules (not to the same extent as β-anomeric repeating units of cellulose and cellulose derivatives). Is obtained. The polymer molecules formed by the β-anomer show strong hydrogen bonds between adjacent molecules, resulting in a mass of polymer molecules and much higher crystallinity. Starches and starch derivatives, which lack the alignment of substituents favoring the strong intermolecular bonds found in cellulose repeat units, disperse in water much more easily.

The water dispersible starch used in the practice of this invention is cationic, ie it contains an overall net positive charge when dispersed in water. Starch is usually made cationic by esterifying or etherifying at one or more free hydroxyl sites to attach a cation substituent to the α-D-glucopyranose unit. Reactive cation donating reagents typically contain primary, secondary or tertiary amino groups (which can subsequently be protonated to their cationic form under the intended conditions of use) or quaternary ammonium, sulfonium or phosphonium groups. Including.

To be useful as a peptizer, the cationic starch must be water dispersible. Many starches disperse in water when heated to temperatures below boiling for a short time (eg, 5-30 minutes). High shear mixing also facilitates starch dispersion. The presence of cationic substituents increases the polarity of the starch molecule and facilitates dispersion. The starch molecules are preferably at least colloidally dispersed, ideally at the molecular level, i.e.
Dissolve.

The following patents describe water dispersible cationic starches within the scope of this invention:
* US Patent No. 2,989,520 (Rutenberger
g.), U.S. Pat. No. 3,017,294 (Meise).
l), U.S. Pat. No. 3,051,700 (Elizer
Et al., U.S. Pat. No. 3,077,469 (Assolo).
s), U.S. Pat. No. 3,136,646 (Elizer)
, * US Patent No. 3,219,518 (Barbe
r *), * US Pat. No. 3,320,080 (Mazz
Arella et al.), US Pat. No. 3,320,118 (Black et al.), US Pat. No. 3,243,426 (Caesar et al.), US Pat. No. 3,336,292 (Kirby), US Pat. 354, 034 (J
arowenko), US Pat. No. 3,422,087 (Caesar), * US Pat. No. 3,467,608 (Dishburger et al.), * US Pat.
7,647 (Beaninga et al.), U.S. Pat.
671,310 (Brown et al.), U.S. Pat. No. 3,7.
06,584 (Cescato et al.), U.S. Pat.
737,370 (Jarowenko et al.), * US Patent 3,770,472 (Jarowenko), US Patent 3,842,005 (Moser et al.), US Patent 4,060,683 (Tessler), U.S. Pat. No. 4,127,563 (Rankin et al.), U.S. Pat. No. 4,613,407 (Huchette et al.),
U.S. Pat. No. 4,964,915 (Blixt et al.), *
US Pat. No. 5,227,481 (Tsai et al.) And *
U.S. Pat. No. 5,349,089 (Tsai et al.).

A specifically preferred form of starch is that which has been oxidized before (after the patent marked with * above) or after the addition of cationic substituents. This oxidation is achieved by treating the starch with a strong oxidant. Both hypochlorite (ClO ⁻ ) or periodate (IO ₄ ⁻ ) have been extensively used and studied in the preparation of commercial starch derivatives and are preferred. Although any convenient counterion can be used, preferred counterions are those that are well compatible with the preparation of silver halide emulsions such as alkali and alkaline earth cations, most commonly sodium and potassium. Or it is calcium.

When the oxidizing agent opens the α-D-glucopyranose ring, the oxidation sites are the 2nd and 3rd carbon atoms constituting the α-D-glucopyranose ring. The 2- and 3-position groups are commonly referred to as "glycol groups."

[0040]

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The carbon-carbon bond between glycol groups is replaced in the following way:

[0042]

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(In the formula, R represents an atom that completes an aldehyde group or a carboxyl group). Hypochlorite oxidation of starch is widely used industrially. A small amount of hypochlorite (chlorine <0.1% by weight, based on total starch) is used to modify the impurities in the starch, most notably to bleach the colored impurities. These low levels of starch modification are minor and, at best, affect only the polymer chain terminal aldehyde groups, not the α-D-glucopyranose repeating unit itself. At the level of oxidation that affects the α-D-glucopyranose repeat unit, hypochlorite is 2
Affecting the 3-, 6-, and 6-positions, lower levels of oxidation form aldehyde groups, and higher levels of oxidation form carboxyl groups. Oxidation is performed at weakly acidic or alkaline pH (eg> 5-11). The oxidation reaction is exothermic and requires cooling of the reaction mixture. Temperature 4
It is preferably maintained below 5 ° C. It is known that the use of a hypobromite oxidant gives results similar to those of hypochlorite.

Hypochlorite oxidation is catalyzed by the presence of bromide ions. It is usually used as a dispersion medium for high bromide silver halide emulsions in order to avoid accidental reduction of silver ions (fogging) by precipitating silver halide emulsions in the presence of an excess of the halides than the theoretical amount. Contains bromide ion. That is, it is specifically contemplated to add the bromide ion to the starch before carrying out the oxidation step at a concentration known to be useful in the precipitation of silver halide emulsions.

US Pat. No. 3,706,584 (Ces
discloses a method for the hypochlorite oxidation of cationic starch. Sodium bromate, sodium chlorite and calcium hypochlorite are listed as alternatives to sodium hypochlorite. The hypochlorite oxidation of starch is further taught in the following references: R.S. L. Whistler, E.I. G. FIG. Link
e and S. Kazeniac, "Action of
Alkaline Hypochloriteon C
orn Starch Amylose and Me
thyl 4-O-Methyl-D-glucopy
ransides ", Journal Amer.
Chem. Soc. , Vol. 78, pp. 4704-47
09 (1956), R.A. L. Whistler and R.M. Schweiger, "Oxidation of
Amylopectin with Hypochl
orite at Different Hydro
en Ion Concentrations ”, Jo
internal Amer. Chem. Soc. , Seventh
9, pages 6460-6464 (1957), J. Am.
Schmorak, D.M. Mejzler and M.M. Lew
in, “A Kinetic Study of the
Mild Oxidation of Where
Starch by Sodium Hypochlo
Ride in the Alkaline pH R
angle ”, Journal of Polymer
Science, Volume XLIX, pages 203-216 (1961), J. Mol. Schmorak and M.D. Lew
in, “The Chemical and Phys
eco-chemical Properties o
f Where Starch with Alkal
in Sodium Hypochlorite ”,
Journal of Polymer Science
e: Part A, Volume 1, pages 2601 to 2620 (1963), K.S. F. Patel, H.M. U. Meh
ta and H.A. C. Srivastava, “Kinet
icsand Mechanism of Oxida
tion of Starch with Sodiu
m Hypochlorite ”, Journalof
Applied Polymer Science,
Vol. 18, pp. 389-399 (1974), R.S.
L. Whistler, J .; N. Bemiller and E.I. F. Pashall, Starch: Chemi
story and Technology, Chapter X, S
tarch Derivatives: Product
ion and Uses, II. Hypochlor
ite-Oxidized Starches, No. 31
Pages 5 to 323, Academic Press, 19
1984 and O.I. B. Wurxburg, Modify
d Starches: Properties and
Uses, III. Oxidized or Hyp
ochlorite-Modified Starch
es, pages 23-28 and 245-246, C
RC Press (1986). The hypochlorite oxidation is usually carried out using soluble salts, but alternatively:
M. E. FIG. McKillican and C.I. B. Purve
s, "Estimation of Carboxy
1, Aldehyde and Ketone Gro
ups in Hypochlorous Acid
Oxystarches ", Can. J. Chem.,
Free acids as described in Volumes 312-321 (1954) can also be used.

Periodate oxidants are of particular importance because they are known to be very selective. The periodate oxidant produces starch dialdehyde by the reaction shown in formula (II) above without significant oxidation at the 6-carbon atom. Unlike hypochlorite oxidation, periodate oxidation does not produce a carboxyl group and does not produce oxidation at the 6-position. US Pat. No. 3,251,826 (M
(Ehlretter) discloses the use of periodic acid to produce starch dialdehyde followed by modification to the cationic form. Also, Mehltrette
r discloses the use of periodate and soluble salts of chlorine as oxidants. The periodate oxidation of starch is further taught in the following references: V. C. Barry and P.M. W. D. Mitche
ll, "Properties of Periodat
e-oxidized Polysaccharide
s. Part II. The Structure o
f some Nitrogen-containin
g Polymers ", Journal Amer.
Chem. Soc. , 1953, pp. 3631-36.
P. 35, p. J. Borchert and J. Mirz
a, “Cationic Dispersions o
f Dialdehyde Starch I.F. The
ory and Preparation ", Tapp
i, Vol. 47, No. 9, 525-528 (196
4 years), J. E. FIG. McCormick, “Proper
ties of Periodate-oxide
d Polysaccharides. Part VI
I. The Structure of Nitrog
en-containing Derivatives
as deduced from a Study o
f Monosaccharide Analogue
s ", Journal Amer. Chem. So
c. , Pages 2121 to 2127 (1966), and O.I. B. Wurzburg, Modified Sta
rches: Properties and Use
s, III. Oxidized or Hypoch
lorite-Modified Starches,
Pages 28-29, CRC Press (1986
Year).

Starch oxidation by electrolysis is described in F. F.
Farley and R.F. M. Hixon, “Oxidat
ion of Raw Starch Granule
sby Electrolysis in Alkal
ine Sodium Chloride Solut
Ion ", Ind. Eng. Chem., 34, 677-681 (1942).

Depending on the choice of oxidizing agent used, one or more soluble salts may be released during the oxidation process. The soluble salts correspond to those normally present during silver halide precipitation,
If they are similar, the soluble salt need not be separated from the oxidized starch prior to silver halide precipitation. Also, of course, the soluble salt can be separated from the oxidized cationic starch prior to precipitation using any conventional separation method. For example, excess halide can be removed in excess of the amount desired to be present during grain precipitation. As a simple alternative, the solute and dissolved salt may simply be decanted from the oxidized cationic starch particles. Another preferred alternative is washing under conditions that do not solubilize the oxidized cationic starch. Even if the oxidized cationic starch is dispersed in the solute during oxidation, it can be separated using conventional ultrafiltration due to the large molecular size separation between the oxidized cationic starch and the soluble salt by-product of oxidation.

The carboxyl group formed by oxidation is
It takes the form of -C (O) OH, but if desired, the carboxyl group can be further treated with -C (O) OR '.
(In the formula, R ′ represents an atom constituting a salt or an ester)
Can take the form of. The organic component added by esterification preferably has 1 to 6 carbon atoms, and optimally has 1 to 3 carbon atoms.

The intended minimum degree of oxidation is that required to reduce the viscosity of the starch. It is generally accepted that opening the α-D-glucopyranose ring in the starch molecule disrupts the linear helix shape of the repeating unit, thereby reducing the solution viscosity (see the cited document). It is contemplated that on average at least one α-D-glucopyranose repeat unit per starch polymer is ring-opened in the oxidation step. When the number of opened α-D-glucopyranose rings is as small as 2 or 3 per polymer, it has a great effect on the ability of the starch polymer to maintain the linear helical shape. Generally, it is preferred that at least 1% of the glucopyranose rings be opened by oxidation.

Preferably, the viscosity of the cationic starch is reduced by oxidation to less than 4 times the viscosity of water (less than 400%) at the starch concentration used for silver halide precipitation.
This reduction in viscosity can be achieved at much lower levels of oxidation, but with 9% of the α-D-glucopyranose repeating units.
Starch oxidation of less than 0% has been reported (Wur above).
zburg, page 29). However, it is preferable to avoid the oxidation proceeding beyond the level generally required for viscosity reduction, as excess oxidation increases chain cleavage. Typically a convenient range of oxidation is α-D
-3 to 50% of the glucopyranose rings are open.

The water-dispersible cationic starch is present during precipitation of the high bromide {111} tabular grains (during nucleation and grain formation or grain growth). Preferably the precipitation is carried out using water dispersible cationic starch in place of all conventional gelatino-peptizers. When the selected cationic starch peptizer is used in place of a conventional gelatin peptizer, the concentration and time of addition (single or multiple) of the selected peptizer are different from those with gelatin peptizer. Can be similar.

Furthermore, it was unexpectedly found that higher concentrations of selected peptizers could be used for emulsion precipitation. For example, all of the selected peptizers needed to prepare the emulsion via a chemical sensitization step can be present in the reaction vessel prior to grain nucleation. This has the advantage that the deflocculating agent need not be added after tabular grain emulsion precipitation has begun. Generally, it is preferred that 1 to 500 g (most preferably 5 to 100 g) of the selected peptizer be present in the reaction vessel prior to tabular grain nucleation per mole of silver to be precipitated.

On the other hand, the presence of a peptizer is not required during grain nucleation and, if desired, the addition of a selected peptizer is added to avoid tabular grain agglomeration. That the addition of a peptizer can be postponed until the particle growth has progressed to the point where is actually needed, US Pat.
Of course, it is well known as shown in No. 34,012 (Mignot).

The high bromide {111} tabular grain emulsion preparation process via completion of tabular grain growth need only use the selected peptizer in place of the conventional gelatin peptizer. The following high bromide {111} tabular grain emulsion precipitation methods are given as specific examples of precipitation methods useful in the practice of this invention subject to the selected peptizer modifications described above: US Pat. , 414, 310 (Dauben
Diek et al.), US Pat. No. 4,425,426 (Ab
bottom et al., U.S. Pat. No. 4,434,226 (Wi
Lgus et al.), US Pat. No. 4,435,501 (Ma
Skasky), U.S. Pat. No. 4,439,520 (K
ofron), US Pat. No. 4,433,048 (S
Olberg et al.), U.S. Pat. No. 4,504,570 (Evans et al.), U.S. Pat. No. 4,647,528 (Yamada et al.), U.S. Pat. No. 4,672,027 (Dau).
bendiek et al.), U.S. Pat. No. 4,693,964 (Daubendiek et al.), U.S. Pat. No. 4,665.
012 (Sugimoto et al.), US Pat. No. 4,67
2,027 (Daubendiek et al.), US Pat. No. 4,679,745 (Yamada et al.), US Pat.
3,964 (Daubendiek et al.), U.S. Pat. No. 4,713,320 (Maskasky et al.), U.S. Pat. No. 4,722,886 (Nottorf), U.S. Pat. No. 4,755,456 (Sugimoto), U.S.A. Patent No. 4,775,617 (Goda), US Patent No. 4,797,354 (Saito et al.), US Patent No. 4,80.
1,522 (Ellis), US Pat.
461 (Ikeda et al.), U.S. Pat. No. 4,835,095 (Ohashi et al.), U.S. Pat. No. 4,835,322 (Makino et al.), U.S. Pat. No. 4,914,014 (Dauben).
Diek et al.), US Pat. No. 4,962,015 (Ai
da, etc.), US Pat. No. 4,985,350 (Ikeda et al.), US Pat. No. 5,061,609 (Piggin
Et al., US Pat. No. 5,061,616 (Piggin
Et al., US Pat. No. 5,147,771 (Tsaur).
Et al., U.S. Pat. No. 5,147,772 (Tsaur).
Et al., US Pat. No. 5,147,773 (Tsaur).
, U.S. Pat. No. 5,171,659 (Tsaur).
Et al., U.S. Pat. No. 5,210,013 (Tsaur
Et al., US Pat. No. 5,250,403 (Antoni).
ades et al.), US Pat. No. 5,272,048 (Ki
M., et al., US Pat. No. 5,310,644 (Delto
n), U.S. Pat. No. 5,314,793 (Chang)
Et al., US Pat. No. 5,334,469 (Sutton)
Et al., U.S. Pat. No. 5,334,495 (Black).
Et al., US Pat. No. 5,358,840 (Chaffe
e.) and US Pat. No. 5,372,927 (Delta).
on).

The high bromide {111} tabular grain emulsions formed preferably contain greater than 50 mole% bromide and up to 4 mole% iodide, based on silver, with the balance halide being chloride. . Silver bromide, silver iodobromide, silver chlorobromide, silver iodochlorobromide, silver chloroiodobromide tabular grain emulsions are specifically contemplated. Chloride is preferably present in a concentration of 30 mol% or less. The iodide concentration is limited because of the increased processing time due to the presence of iodide.

In all examples, tabular grains account for greater than 50 percent of total grain projected area and preferably account for the largest proportion of total grain projected area that can be conveniently achieved. Preferably at least 70%, most preferably at least 90% and optimally substantially all of the total grain projected area (<9
7%) is accounted for by high bromide tabular grains. The average grain ECD of the high bromide {111} tabular grain emulsions can be any conventional value in the range of 10 μm or less, which is generally acceptable as the maximum average grain size compatible with radiographic imaging. In practice, the tabular grain emulsions of this invention typically have an average ECD of about 0.5 to 5.0.
It is in the range of μm.

The tabular grains generally have an average thickness of less than 0.3 μm, and most preferably less than 0.2 μm. When the emulsions use gelatin and gelatin derivative peptizers as binders, the minimum average tabular grain thickness, which is desirable to hold cold-tone images, is preferably about 0.1 .mu.m. With the exception of the image tones described above, the benefits tabular grains impart to emulsions generally increase as the average aspect ratio or tabularity of the tabular grain emulsion increases. Aspect ratio (ECD / t) and flatness (E
Both CD / t ² ) increase as the average tabular grain thickness decreases. Therefore, it is generally required that the thickness of tabular grains be as small as possible for the intended use. The average aspect ratio of the tabular grains is preferably greater than 5, and most preferably greater than 8, unless otherwise specified for particular applications. The tabular grain average aspect ratio can be up to 100 or more, but is typically in the range of about 12-80. A tabularity of> 25 is generally preferred.

Conventional dopants are described in the above-referenced patents and Research Disclosure, Item 36544, Section I. Emulsion grains and their preparation, D. Particle denaturing conditions and preparation, paragraph (3),
(4) and (5) (Section I. Emuls
ion grains and ther prep
aration, D.A. Grain modifying
conditions and adjustment
s, paragraph (3), (4) and (5))
, Tabular grains can be included during precipitation. Research Disclosu
Re, Volume 367, November 1994, Item 367.
It is specifically contemplated that the tabular grains contain shallow electron trap site donating (SET) dopants as disclosed in US Pat.

It is also contemplated that the silver salt can be epitaxially grown on the tabular grains during the precipitation process. Epitaxial deposition of tabular grains on the edges and / or corners is described in US Pat. No. 4,435,501 (Ma, supra).
Skasky). In a particularly preferred embodiment, the high chloride silver halide epitaxy is particularly preferably present at the edge, most preferably confined to the corner adjacent sites on the tabular grains.

Epitaxy on host tabular grains is
While capable of serving as a sensitizer itself, the emulsions of the present invention may be chemically sensitized in the absence of gelatin or a gelatin derivative using one or a combination of noble metals, intermediate chalcogens and reduction chemical sensitization methods. When sensitized, it shows an unexpected enhancement of sensitivity with or without epitaxy. The usual chemical sensitization by these methods is carried out by the above-mentioned Research D
isclosure, item 36544, section IV. Chemical sensitization
ations). All of these sensitizations are applicable to the practice of this invention, except for those sensitizations that specifically require the presence of gelatin (eg, active gelatin sensitization). It is preferred to use noble metals (typically gold) and intermediate chalcogens (typically sulfur) and most preferably a combination of both to prepare the emulsions of this invention for photography.

Between the emulsion precipitation and the chemical sensitization, which is a step that is preferably completed before adding the gelatin or gelatin derivative to the emulsion, the emulsion is washed to obtain soluble reaction by-products (eg alkali and / or alkali). It is common to remove earth cations and nitrate anions). If desired, US Pat. No. 4,334,012 (Migno
Emulsion washing can be combined with emulsion precipitation using ultrafiltration during precipitation as taught by t). Alternatively, washing the emulsion by diafiltration after precipitation but before chemical sensitization can be carried out using Research Di
Sclossure, Volume 102, October 1972, Item 10208, Hagemeier et al., Research.
rch Disclosure, Volume 131, 1975
March, Item 13122, Bonnet, Res
search Disclosure, Vol. 135, 19
July 1975, Item 13577, Berg et al., Using a semi-permeable membrane as described in German Patent Publication No. 2,436,461 and US Pat. No. 2,495,918 (Bolton), or US Pat. It can be carried out by using an ion exchange resin as described in US Pat. No. 3,782,953 (Maley) and US Pat. No. 2,827,428 (Noble). Washing by these techniques does not have the potential to remove selected peptizers, as ion removal is inherently limited to removal of solute ions of much lower molecular weight than the selected peptizer.

A specifically preferred method of chemical sensitization is a sulfur-containing ripening agent and an intermediate chalcogen (typically sulfur).
And a combination with a noble metal (typically gold) chemical sensitizer. Intended sulfur-containing ripening agents are described in US Pat. No. 3,271,157 (McBride), US Pat. No. 3,574,628 (Jones) and US Pat. No. 3,737,313 (Rosenrants et al.). There are thioethers that are used. A preferred sulfur-containing ripening agent is U.S. Pat. No. 2,222,264.
The thiocyanates described in U.S. Pat. Nos. (Nietz et al.), U.S. Pat. No. 2,448,534 (Lowe et al.) And U.S. Pat. A preferred class of intermediate chalcogen sensitizers are those disclosed in US Pat. Nos. 4,749,646 and 4,81.
Tetra-substituted intermediate chalcogen ureas of the type disclosed in 0,626 (Herz et al.). Preferred compounds include those of the formula:

[0064]

Embedded image

(In the formula, X is sulfur, selenium or tellurium; R ₁ , R ₂ , R ₃ and R ₄ are each independently an alkylene group, a cycloalkylene group, an alkarylene group,
R ₁ , R ₂ , R ₃ and R ₄ together with the nitrogen atom to which they represent an aralkylene or heterocyclic arylene group complete a 5- to 7-membered heterocycle; and A ₁ ,
A ₂ , A ₃ and A ₄ each independently represent a group containing hydrogen or an acidic group, provided that at least one of A ₁ R _{1 to} A ₄ is present via a carbon chain having 1 to 6 carbon atoms. R ₄ contains an acidic group attached to the urea nitrogen).

X is preferably sulfur, and A ₁ R ₁ ~
A ₄ R ₄ is preferably methyl, or carboxymethyl in which the carboxy group can be in the acid or salt form.
A specifically preferred tetra-substituted thiourea sensitizer is 1,3-
It is dicaboxymethyl-1,3-dimethylthiourea. A preferred gold sensitizer is US Pat. No. 5,049,48.
It is a gold (I) compound disclosed in No. 5 (Deaton). These compounds include those represented by the formula: AuL ₂ ⁺ X ⁻ or AuL (L ¹ ) ⁺ X ⁻ (IV) where L is a mesoionic compound and X is an anion. L ¹ is a Lewis acid donor).

In another preferred embodiment of the invention, the compound of formula III
Sulfur sensitizers such as those of formula IV and / or gold sensitizers such as those of formula IV, US Pat. No. 4,378,42
2- [N- (2-alkynyl) amino]-disclosed by No. 6 and No. 4,451,557 (Lok et al.).
It is intended to use the reduction sensitizers, which are meta-calcoazoles, alone or in combination.

A preferred 2- [N- (2-alkynyl) amino] -meta-calcoazole can be represented by formula V:

[0069]

Embedded image

(Wherein X is O, S or Se; R ₁
Is (Va) hydrogen or (Vb) alkyl or substituted alkyl or aryl or substituted aryl; Y ₁ and Y ₂ are independently hydrogen, an alkyl group or an aromatic nucleus or together carbon, oxygen, selenium. And the atoms necessary to complete an aromatic or alicyclic ring containing atoms selected from nitrogen atoms.

The compound represented by the formula V is effective when it is present in the heating step (finishing) which generally causes chemical sensitization (Vb type gives very high sensitivity and latent image stability. Is very good). It is contemplated that the emulsions of this invention are spectrally sensitized even when the emulsions are used in photography in the spectral region where tabular grains exhibit significant intrinsic sensitivity. Adsorption of the spectral sensitizing dye significantly reduces crossover. Furthermore, the highest achievable imaging efficiency is obtained when the preferred green emission intensifying screen is used in combination with a spectral sensitizing dye having a peak absorption corresponding to the peak emission band of the intensifying screen. Spectral sensitization is most commonly performed after chemical sensitization, but spectral sensitizing dyes are added earlier than grain nucleation, added before grain nucleation, and added before grain nucleation. Is advantageous. U.S. Pat. No. 4,439,520 (Kofron
Et al.) Disclose the advantage of "dye in finish" sensitization by introducing a spectral sensitizing dye into the emulsion prior to the heating step (finishing) that results in chemical sensitization. U.S. Pat. No. 4,435,501
(Masksky) teaches the use of agglomerated spectral sensitizing dyes, especially green and red cyanine absorbing dyes, as site directors for epitaxial deposition. These dyes are present in the emulsion before the chemical sensitizing finishing step. A much broader range of spectral sensitizing dyes can be used when the spectral sensitizing dye present in the finish need not act as a site director for silver salt epitaxy. The spectral sensitizing dyes disclosed by Kofron et al., In particular the blue spectral sensitizing dyes whose structures are shown, and their longer chain methine chain analogues, which exhibit maximum absorption in the green and red parts of the spectrum, are Particularly preferred for inclusion in the tabular grain emulsions of the invention. A more general compilation of useful spectral sensitizing dyes is Research Di.
sclossure, item 36544, section V.6. Spectral sensitization and desensitization (Spectral sensi)
Tization and Desensitization
Ion).

In a particularly preferred embodiment of the invention, the spectral sensitizing dye acts as a site director and / or is present in the finish, but the only spectral sensitizing dye that must be fulfilled in the emulsions of the invention. The required function is to increase the sensitivity of the emulsion to at least one region of the spectrum. Thus, spectral sensitizing dyes can be added to the emulsions according to the invention after chemical sensitization is complete, if desired.

Additional vehicle is added to the emulsions of this invention, either after chemical sensitization and before coating.
Conventional vehicles and related emulsion ingredients are found in Research above.
hDisclosure, Item 36544, Section II. Vehicles, vehicle extenders, vehicle-like additives and vehicle-related additives (Vehicles, veh
icle extenders, vehicle-li
ke addenda and vehicle re
later added). Also, hydrophilic colloid binders for protective overcoats and crossover reducing layers can be selected from conventional vehicles. The layer can be cured to facilitate rapid processing using conventional techniques. When the cationic starch is only present in the emulsion layer as a peptizer, its concentration is too low to have any effect on hardening. Common hardeners are found in Research Disclosure, Item 36544, Section II, B.I. Hardener (Har
denders). When starch is used as a binder, acceptable cold-conditioning images can be achieved with tabular grain thicknesses much less than 0.1 .mu.m, and ultrathin tabular grain emulsions, ie, tabular grains having an average thickness of .0. It is specifically contemplated to use starch as a binder in the case of emulsions that are less than 07 μm.

It has been found that replacing the gelatin and gelatin derivatives used as binders in the emulsion layer with starch improves the radiographic element by shifting the developed silver image to a cooler (preferred) image. The same cationic starch as described above used as a peptizer can also be used as a binder for the emulsion layer,
And for convenience, it can be used with other hydrophilic colloid layers if desired. However, it is not required that the starch be cationic in order to obtain a cooler image.

When starch is used as the binder, it can be hardened using conventional starch cross-linking agents. The most widely used cross-linking agent for starch is epichlorohydrin. Other known cross-linking agents include β, β'-dichlorodiethyl ether; dibasic organic acids reacted under conditions such that both carboxyl groups esterify the hydroxyl groups of starch; phosphorus oxychloride; trimeta. Phosphate; mixed anhydride of acetic acid and di- or tribasic carboxylic acid; vinyl sulfone; diepoxide; cyanuric chloride; hexahydro-1,3,5-trisacryloyl-s-triazine; hexamethylene diisocyanate; toluene 2,4-diisocyanate; N, N-dimethylene-bisacrylamide; N, N'-bis (hydroxymethyl) ethyleneurea; phosgene; tripolyphosphate; mixed carbonic acid-carboxylic acid anhydrides; carbonic acid and polybasic carboxylic acid imidazolides; polybasic carboxylic acid imidazo Lithium salt; guar of polycarboxylic acid Esters of propionic acid; derivative and an aldehyde (e.g., formaldehyde, acetaldehyde and acrolein) and the like. These and similar crosslinkers are described in US Pat.
113,034 (Rowland et al.), US Pat. No. 2,328,537 (Felton et al.), US Pat. No. 2,417,611 (Pierson), US Pat. No. 2,461,139 (Caldwell), US Patent No. 2,469,957 (Fenn), US Patent No. 2,
524,400 (Schoene et al.), U.S. Pat. No. 2,626,257 (Caldwell et al.), U.S. Pat. No. 2,438,855, 2,801,242,
No. 2,852,393 and No. 2,938,901 (Kerr et al.), US Pat. No. 2,929,811 (H
ofreiter et al.), US Pat. No. 2,989,521.
No. 2 (Senti et al.), US Pat. No. 2,977,356 (Commerford et al.), US Pat.
220 (Gerwitz), US Pat. No. 2,910,
467 (Wimmer), US Pat. No. 3,035,0
No. 45 and No. 3,086,971 (Trimmell
Et al., U.S. Pat. No. 3,001,985 (Sowell
Et al., U.S. Pat. No. 3,069,410 (Smith
Et al., U.S. Pat. No. 3,376,287 (Jarowe.
nko et al.), US Pat. Nos. 3,549,618 and 3,705,046 (Speakman), US Pat. No. 3,553,195 (Jarowenko), US Pat. Nos. 3,699,095 and 3 , 728, 332
(Tessler et al.) And U.S. Pat. No. 4,020,
No. 272 and No. 4,098,997 (Tessle
r). The use of hardeners of the type having two or more active olefin groups (a preferred type of hardener for gelatin and gelatin derivatives) is shown in the examples below.

Except for the starch replacements described above, the radiographic elements of this invention can take any convenient conventional form. The following patents disclose the construction of conventional radiographic elements: RE-1 US Pat. No. 4,414,304 (Dickerson) RE-2 US Pat. No. 4,425,425 (Abbott et al.) RE -3 U.S. Patent No. 4,425,426 (Abbott et al.) RE-4 U.S. Patent No. 4,803,150 (Kelly et al.) RE-5 U.S. Patent No. 4,900,652 (Kelly et al.) RE-6 U.S. Pat. No. 4,994,355 (Dickerson et al.) RE-7 U.S. Pat. No. 4,997,750 (Dickerson et al.) RE-8 U.S. Pat. No. 5,021,327 (Bunch et al.) RE-9 U.S. Patent No. 5,041,364 (Childrens et al.) RE-10 US Pat. No. 5,108,881 (Dickerson et al.) RE-11 US Pat. No. 5,252,442 (Tsaur et al.) RE-12 US Pat. No. 5,252,443 (Dickerson et al.) RE-13 US Pat. No. 5,259,016 (Steklenski et al.) RE-14 US Patent No. 5,391,469 (Dickerson) Common radiographic element components are Research Di
Sclossure, Volume 184, August 1979, Item 18431, particularly as summarized below: I. Emulsion stabilizer, antifoggant and antikink agent (Em
ulsion stabilizers, Antifo
ggants and Antikinking Ag
ents) III. Antistatic agent / layer (Antistatic Ag)
ents / Layers) IV. Overcoat layer (Overcoat Layer)
rs) V. Crossover exposure control (Cross-Over E
xpose Control) IX. X-ray screen / phosphor (X-Ray Screen
ens / Phosphors) X. Spectral sensitization (Spectral Sensitiza)
section) XII. Film support (Film Support)
s) The photographic element features summarized in the following sections of Research Disclosure, Item 36544, are also applicable to radiographic element constructions: Spectral sensitization and desensitization A. Sensitizing dye (Spectra
l sensitization and desen
Situation A. Sensitizing
dyes) VII. Antifoggants and stabilizers (Antifogga)
nts and stabilizers) IX. Coating physical property additive (Coating phys)
iCal property modifying a
ddenda) A. Coating aids B. Plasticizers and lubricants (Plasticizers an
d Lubricants) C.I. Antistatic Agent D. Matting agents

[0077]

EXAMPLES The present invention can be better understood with reference to the following specific examples. Unless stated otherwise, all weight percentages (wt%) are on a total weight basis. Examples 1-17 These examples demonstrate the precipitation of tabular grain emulsions with cationic starch from different plant sources including various potato and grain sources. The starch was chosen to have a wide range of nitrogen and phosphorus contents. Changes in emulsion precipitation conditions are also shown. Of particular importance is to show that all of the cationic starch used throughout the precipitation can be added before grain nucleation. Example 1: AgIBr (3 mol% I) tabular grain emulsion prepared with cationic potato starch Cationic potato starch (AE Stanley Manufacturi, Decatur, IL)
STA-LOK (trademark) 400) 8 obtained from ng company
A starch solution was prepared by boiling a stirred mixture of 0 g, 27 mmol of NaBr, and distilled water (the amount needed to bring the total to 4 liters) for 30 minutes. The cationic starch was a mixture of 21% amylose and 79% amylopectin, containing 0.33% by weight nitrogen in the form of a quaternary trimethylammonium alkyl starch ether and 0.13% by weight natural phosphorus. .. The cationic starch had an average molecular weight of 2200000. The resulting solution was cooled to 35 ° C., readjusted to 4 liters with distilled water, and the pH adjusted to 5.5. Add 2 M A to the starch solution at 35 ° C that was placed in a reaction vessel and vigorously stirred.
The gNO ₃ solution was added at 100 ml / min for 0.2 minutes.
At the same time, a salt solution of 1.94 M NaBr and 0.06 MKI was first added at 100 ml / min, followed by a pBr of 2.2.
Added at the flow rate required to maintain 1. Then, after stopping the addition of the solution, 25 ml of a 2M NaBr solution was rapidly added, and the temperature of the content in the reaction vessel was raised to 60 ° C. at a temperature rising rate of 5 ° C./3 minutes. At 60 ° C., the AgNO ₃ solution was added at 10 ml / min for 1 minute, and the total addition rate was 1.
It was accelerated to 50 ml / min for 30 minutes until the addition of 00 liters. The salt solution was added simultaneously at the rate required to maintain a constant pBr of 1.76. The resulting tabular grain emulsion was washed by diafiltration at 40 ° C to a pBr of 3.38.

The tabular grain population of the resulting tabular grain emulsion had an average equivalent circular diameter of 1.2 μm and an average thickness of 0.06 μm.
m, and the average aspect ratio was 20. The tabular grain population accounted for 92% of the total projected area of the emulsion grains. The diameter variation coefficient of the emulsion grains was 18%. Example 2: AgIBr (3 mol% I) tabular grain emulsion prepared with cationic corn starch 2.7 mmol of NaBr and 0.31 wt% nitrogen content.
Cationic hybrid corn starch with 0.00 wt% phosphorus content (National Starch and Chemi, Bridgewater, NJ
CATO (trademark) 235) 8.0 obtained from Cal Co.
While stirring 400 g of an aqueous mixture containing 30 g
A starch solution was prepared by boiling for minutes.

The resulting solution was cooled to 35 ° C. and readjusted to 400 g with distilled water. 2M AgN was added to a starch solution having a pH of 5.5 at 35 ° C, which was placed in a reaction vessel and vigorously stirred.
The O ₃ solution was added at a constant rate of 10 ml / min. At the same time, a salt solution of 1.94 M NaBr and 0.06 M KI was added initially at 10 ml / min, followed by the flow rate required to maintain pBr at 2.21. After 0.2 minutes, the addition of the solution was stopped, 2.5 ml of a 2M NaBr solution was rapidly added, and the temperature of the contents of the reaction vessel was raised to 60 ° C at a heating rate of 5 ° C / 3 minutes. At 60 ° C., AgNO ₃ solution was added at 1.0 ml / min for 1 minute, and the addition rate was 1 in total.
30 minutes before adding 00 ml of AgNO ₃ solution, 5
Accelerated to ml / min. The salt solution was added simultaneously at the rate required to maintain a constant pBr of 1.76.

The tabular grain population of the resulting emulsion comprised tabular grains having an average equivalent circular diameter of 1.6 μm, an average thickness of 0.06 μm and an average aspect ratio of 27. The tabular grain population is 85% of the total projected area of the emulsion grains.
Was occupied. Example 3: AgIBr (3 mol% I) tabular grain emulsion prepared with cationic amphoteric potato starch. The starch used was quaternary trimethylammonium alkyl starch ether (0.36 wt% nitrogen) and orthophosphate (phosphorus). 0.70 wt%) cationic amphoteric potato starch containing both substituents (Western Polymer, Moses Lake, WA).
The emulsion of this example was prepared in the same manner as in Example 2 except that it was Wespol A (trademark) obtained from Company r.

The tabular grain population of the resulting emulsion comprised tabular grains having an average equivalent circular diameter of 1.7 μm, an average thickness of 0.05 μm and an average aspect ratio of 34. Tabular grain population is 95% of total projected area of emulsion grains.
Was occupied. Example 4: AgIBr (3 mol% I) tabular grain emulsion prepared using cationic amphoteric potato starch This example emulsion was prepared in the same manner as in Example 3 except that precipitation was stopped after adding 50 ml of AgNO ₃ solution. Was prepared.

The tabular grain population of the resulting emulsion comprised tabular grains having an average equivalent circular diameter of 1.0 μm, an average thickness of 0.045 μm and an average aspect ratio of 25. The tabular grain population is 95% of the total projected area of the emulsion grains.
Accounted for%. Example 5: Cationic potato starch and pH 2.0
AgIBr (3 mol% I) tabular grain emulsions prepared with the aid of a cationic potato starch (STA-LOK ™).
The emulsion of this example was prepared in the same manner as in Example 2 except that the emulsion was 400).

The tabular grain population of the resulting emulsion comprised tabular grains having an average equivalent circular diameter of 1.5 μm, an average thickness of 0.06 μm and an average aspect ratio of 22. The tabular grain population is 80% of the total projected area of the emulsion grains.
Was occupied. Example 6: AgIBr (3 mol% I) tabular grain emulsion prepared with cationic corn starch An emulsion was precipitated at pH 6.0 and the starch used was in the form of a quaternary trimethyl ammonium alkyl starch ether. Cationic waxy maize starch (AE Stanley Ma) composed of 0.36% by weight nitrogen, 0.06% by weight phosphorus, and 100% amylopectin derivatized to have an average molecular weight of 324,000.
STA-LOK obtained from Nufacturing
The emulsion of this example was prepared in the same manner as in Example 2 except that it was (trademark) 180).

The tabular grain population of the resulting emulsion was comprised of tabular grains having an average equivalent circular diameter of 1.6 μm, an average thickness of 0.06 μm and an average aspect ratio of 27. The tabular grain population is 91% of the total projected area of the emulsion grains.
Was occupied. Example 7: AgBr tabular grain emulsion prepared by adding 94% of cationic potato starch after grain nucleation Aqueous mixture containing 3.75 mmol of NaBr and 8.0 g of cationic potato starch STA-LOK ™ 400. A starch solution was prepared by boiling 200 g with stirring for 30 minutes.

12.5 g of starch solution (0.5 starch
g), 387.5 g of distilled water and 2.2 mmol of NaBr were placed in a reaction vessel with vigorous stirring (pH 6.0,
35 ° C.), 2M AgNO ₃ solution was added at a constant rate of 10 ml / min. At the same time, add 2.5M NaBr solution
After the initial addition at 10 ml / min, the pBr was added at the flow rate required to maintain 2.21. After 0.2 minutes, the addition of the solution was stopped, 2.5 ml of 2M NaBr was rapidly added, and the temperature of the contents of the reaction vessel was raised to 60 ° C at a heating rate of 5 ° C / 3 minutes. At 60 ° C., the above starch solution 18
7.5 g (7.5 g of starch) were added and the pH was adjusted to 6.0.
To maintain this value for the rest of the precipitation.
₃ solution was added at 1.0 ml / min for 3 minutes and N
The aBr solution was added simultaneously at the rate required to maintain pBr at 1.76. After that, the addition of the NaBr solution was stopped, but the addition of AgNO ₃ was continued at 1.0 ml / min until the pBr reached 2.00. Then, AgNO ₃ was added at 0.05 ml / min, and the NaBr solution was added at a rate necessary to maintain pBr 2.00 until the addition amount became 0.20 mol of total silver.

The tabular grain population of the resulting emulsion comprised tabular grains having an average equivalent circular diameter of 1.0 μm, an average thickness of 0.055 μm and an average aspect ratio of 18. The tabular grain population is 90% of the total projected area of the emulsion grains.
Accounted for%. Example 8: AgIBr (3 mol% I) tabular grain emulsion prepared with cationic amphoteric corn starch. The starch used was quaternary trimethyl ammonium alkyl starch ether (0.34 wt% nitrogen) and orthophosphate (phosphorus). 1.15 wt%) cationic amphoteric corn starch containing both (A.E.
The emulsion of this example was prepared in the same manner as in Example 2 except that it was STA-LOK (trademark) 356) obtained from Stanley Manufacturing Co. Cationic amphoteric starch is a mixture of 28% amylose and 72% amylopectin with an average molecular weight of 486,000.
Met.

The tabular grain population of the resulting emulsion was comprised of tabular grains having an average equivalent circular diameter of 1.6 μm, an average thickness of 0.07 μm and an average aspect ratio of 23. The tabular grain population is 80% of the total projected area of the emulsion grains.
Was occupied. Example 9: AgBr tabular grain emulsion prepared with cationic potato starch Cationic potato starch (STA-LOK ™).
400) 8.0 g and 6.75 mM NaBr solution (3
5 ° C., pH 6.0) with vigorous stirring were added to a reaction vessel 400 g, was added 2M AgNO ₃ solution at 10 ml / min. At the same time, a 2M NaBr solution was added initially at 10 ml / min, followed by the flow rate required to maintain pBr at 2.21. After 0.2 minutes, the addition of the solution was stopped, 2.5 ml of 2M NaBr was added rapidly, and the temperature was raised to 60 ° C at a heating rate of 5 ° C / 3 minutes. 60 ° C
Then, after adding AgNO ₃ solution at 1.0 ml / min for 1 minute,
After accelerating the addition rate to 5 ml / min in 30 minutes, this rate was maintained until a total of 200 ml AgNO ₃ solution was added. The salt solution was added simultaneously at the rate required to maintain a constant pBr of 1.76.

The tabular grain population of the resulting emulsion comprised tabular grains having an average equivalent circular diameter of 2.2 μm, an average thickness of 0.08 μm and an average aspect ratio of 28. The tabular grain population is 85% of the total projected area of the emulsion grains.
Was occupied. Example 10: AgIBr (3 mol% I) Tabular Grain Emulsion with Protonated Tertiary Aminoalkyl (Cation) Corn Starch The starch used was the corn starch (National Starch and Chem) that was obtained.
CATO-SIZE ™ 6 obtained from ical
An emulsion of this example was prepared in the same manner as in Example 2 except that 9) was derivatized to contain tertiary aminoalkyl starch ether, 0.25% by weight of nitrogen, and 0.06% by weight of phosphorus. At pH 5.5, the tertiary amino groups were protonated to make the starch cationic.

The tabular grain population of the resulting emulsion comprised tabular grains having an average equivalent circular diameter of 1.2 μm, an average thickness of 0.08 μm and an average aspect ratio of 15. The tabular grain population is 55% of the total projected area of the emulsion grains.
Was occupied. Example 11: pH with cationic potato starch
5.5 AgIBr (3 mol% I) prepared at 80 ° C
Tabular grain emulsion The used starch is cationic potato starch (ST
A-LOK (trademark) 400) and a temperature of 80 ° C.
The emulsion of this example was prepared in the same manner as in Example 2 except that the temperature was raised (instead of 60 ° C.).

The tabular grain population of the resulting emulsion comprised tabular grains having an average equivalent circular diameter of 1.7 μm, an average thickness of 0.07 μm and an average aspect ratio of 24. The tabular grain population is 80% of the total projected area of the emulsion grains.
Was occupied. Example 12: AgIBr (3 mol% I) tabular grain emulsion prepared with cationic corn starch. The starch used was 0.26% by weight nitrogen and 0.0% phosphorus.
An emulsion of this example was prepared in the same manner as in Example 2 except that it was a cationic corn starch (CATO (trademark) 25) containing 0% by weight.

The tabular grain population of the resulting emulsion comprised tabular grains having an average equivalent circular diameter of 1.2 μm, an average thickness of 0.07 μm and an average aspect ratio of 17. The tabular grain population is 65% of the total projected area of the emulsion grains.
Was occupied. Example 13: AgIBr (3 mol% I) Tabular Grain Emulsion Prepared with Cationic Corn Starch The starch used was 0.15% by weight nitrogen and 0.0% phosphorus.
Cationic corn starch containing 0% by weight (ADM CornPro, Clinton, Iowa)
Clinton 788 obtained from Cessing
The emulsion of this example was prepared in the same manner as in Example 2 except that (trademark) was used.

The tabular grain population of the resulting emulsion was comprised of tabular grains having an average equivalent circular diameter of 1.0 μm, an average thickness of 0.08 μm and an average aspect ratio of 13. The tabular grain population is 60% of the total projected area of the emulsion grains.
Was occupied. Example 14: AgIBr (3 mol% I) Tabular Grain Emulsion Prepared with Cationic Wheat Starch The starch used was the cationic wheat starch obtained (ADM / Og from Montreal, Quebec, Canada).
K-MEGA (trademark) 53 obtained from ilvie
An emulsion of this example was prepared in the same manner as in Example 2 except that S) was derivatized with a quaternary amine. The degree of substitution is 0.050, which corresponds to 0.41% by weight of nitrogen.
Phosphorus was measured by spectrophotometry to be 0.07% by weight.

The tabular grain population of the resulting emulsion was comprised of tabular grains having an average equivalent circular diameter of 1.5 μm, an average thickness of 0.08 μm and an average aspect ratio of 19. The tabular grain population is 85% of the total projected area of the emulsion grains.
Was occupied. Example 15 AgBr Tabular Grain Emulsion Prepared with Cationic Potato Starch 400 g of an aqueous mixture containing 2.7 mmol of NaBr and 8.0 g of cationic potato starch STA-LOK ™ 400 is boiled for 30 minutes with stirring. To prepare a starch solution.

The obtained solution was cooled to 35 ° C. and readjusted to 400 g with distilled water. Starch solution (35 ℃, pH
6.0) in a reaction vessel and 2M with vigorous stirring
AgNO ₃ solution was added at a constant rate of 10 ml / min. At the same time, a 2M NaBr solution was added initially at 10 ml / min and then at the flow rate required to maintain pBr at 2.21. After 0.2 minutes, stop adding the solution and stop
2.5 ml of NaBr was rapidly added, and the temperature of the contents of the reaction vessel was raised to 50 ° C. at a heating rate of 5 ° C./3 minutes.
The pH was adjusted to 6.0 at 50 ° C. and the AgNO ₃ solution was adjusted to 1.
After 1 minute addition at 0 ml / min, the addition rate was 5 minutes in 30 minutes.
After accelerating to ml / min, this speed was adjusted to 20 total AgNO ₃ solution.
Hold until adding 0 ml. Salt solution at constant pBr
Simultaneous additions were made at the rate required to maintain 1.76.

The tabular grain population of the resulting emulsion was comprised of tabular grains having an average equivalent circular diameter of 1.2 μm, an average thickness of 0.10 μm and an average aspect ratio of 12. The tabular grain population is 70% of the total projected area of the emulsion grains.
Was occupied. Example 16: AgIBr (3 mol% I) Tabular Grain Emulsion Prepared with High Nitrogen Cationic Potato Starch A solution of high nitrogen cationic potato starch was added to We.
stern Polymer Corporation
Supplied by The starch was 1.10 wt% nitrogen and 0.25 wt% natural phosphorus.

Starch solution 40 containing 8 g starch
To g, 360 g of distilled water and 2.7 mmol of NaBr were added. This solution was placed in a reaction vessel and used to precipitate the emulsion of this example by the method described in Example 2.
The tabular grain population of the resulting emulsion had an average equivalent circular diameter of 1.
2 μm, average thickness 0.09 μm, average aspect ratio 13
The tabular grains are as follows. The tabular grain population accounted for 80% of the total projected area of the emulsion grains. Example 17 AgBr Tabular Grain Emulsion Prepared with Cationic Potato Starch 400 g of an aqueous mixture containing 2.7 mmol of NaBr and 8.0 g of cationic potato starch STA-LOK ™ 400 is boiled for 30 minutes with stirring. To prepare a starch solution.

The solution obtained is cooled to 35 ° C. and distilled water is added.
Readjusted to 400 g. Starch solution (35 ℃, pH
6.0) in a reaction vessel and 2M with vigorous stirring
 AgNO_ThreeAdd the solution at a constant rate of 10 ml / min
Was. At the same time, 2.5M NaBr salt solution was added to the first 10
Necessary to maintain pBr at 2.21 after addition at ml / min.
It was added at the required flow rate. Stop adding solution after 0.2 minutes
Then, rapidly add 2.5 ml of 2M NaBr, and
Raise the temperature of the contents of the container to 60 ° C at a heating rate of 5 ° C / 3 minutes.
Raised. Adjust the pH to 6.0 at 60 ℃, AgNO_Three
After adding the solution at 1.0 ml / min for 1 minute, change the flow rate to 30
After accelerating to 5 ml / min in minutes, change this speed to AgNO _ThreeSolution
Hold until a total of 200 ml was added. Constant salt solution
Simultaneous addition at the rate required to maintain pBr 1.76
did. Next, the addition of the NaBr solution was stopped and AgNO_Three
The solution flow rate was reduced to 1 ml / min. pBr is 2.28
When the temperature reaches the point p, the flow of the NaBr solution is restarted and the p
Br was maintained. After growing for 60 minutes with this pBr, pBr
Was adjusted to 3.04 and this value was adjusted to 0.53
I kept it until I got it.

The tabular grain population of the resulting emulsion was comprised of tabular grains having an average equivalent circular diameter of 2.0 μm, an average thickness of 0.14 μm and an average aspect ratio of 14. The tabular grain population is 85% of the total projected area of the emulsion grains.
Was occupied. Controls 18-22 These examples show that the selection of non-cationic starch as the peptizer results in poor tabular grain preparation. Control Example 18: AgIBr (3 mol% I) Nontabular Grain Emulsion Prepared with Water Soluble Carboxylated (Non-Cationic) Corn Starch The starch used was the corn starch (National Starch and Chem)
FILMKOTE ™ 5 obtained from ical
An emulsion of this example was prepared in the same manner as in Example 2 except that 4) was derivatized to contain a carboxylate group. The nitrogen content was 0.06% by weight in nature.

A non-tabular grain emulsion was obtained. Control Example 19: AgIB prepared with water soluble orthophosphate derivatized (non-cationic) potato starch
r (3 mol% I) non-tabular grain emulsion Performed except that the starch used was orthophosphate derivatized potato starch (0.03 wt% natural nitrogen) and orthophosphate substituents (0.66 wt% phosphorus). The emulsion of this example was prepared in the same manner as in Example 2. This sample was obtained from Western Polymer.

A non-tabular grain emulsion was obtained. Control Example 20: AgIB prepared with water soluble hydroxypropyl substituted (non-cationic) corn starch
r (3 mol% I) Non-tabular grain emulsion Starch (AE Stanley Manufa)
STARPOL ™ obtained from Cturing
530) is a hydroxypropyl-substituted corn starch (0.06 wt% natural nitrogen and 0.12 wt% phosphorus).
The emulsion of this example was prepared in the same manner as in Example 2 except that

A non-tabular grain emulsion was obtained. Control Emulsion 21: AgIBr (3 mol% I) non-tabular grain emulsion prepared with water soluble (non-cationic) potato starch Starch used (Sigma, St. Louis, MO)
a SOLUBLE obtained from a Chemical Company
Potato Starch has processed and purified water-soluble potato starch (0.04% by weight nitrogen and 0.1% phosphorus).
The emulsion of this example was prepared in the same manner as in Example 2 except that the amount was 06% by weight.

A non-tabular grain emulsion was obtained. Control Example 22: AgIBr (3 mol% I) non-tabular grain emulsion prepared with water soluble (non-cationic) wheat starch Starch used (Superg obtained from ADM / Ogilvie, Montreal, Quebec, Canada)
The emulsion of this example was prepared in the same manner as in Example 2 except that EL (trademark) 1400) was a water-soluble non-cationic wheat starch.

A non-tabular grain emulsion was obtained. Control Example 23: AgIBr (3 mol% I) Nontabular Grain Emulsion Prepared with Grain Protein Zein This example shows that grain protein zein does not act as a peptizer. What added 8.0 g of zein (obtained from Sigma Chemical Co.) to 400 g of distilled water containing 2.7 mmol of NaBr was put in a reaction vessel and boiled for 60 minutes while stirring. Most of the zein did not appear to dissolve. The mixture was filtered and the filtrate was used as a starch solution to precipitate silver halide using the same conditions as in Example 2.

The precipitation produced large agglomerates of nontabular grains. Controls 24-27 These examples show that tabular grains do not precipitate when a non-cationic starch-like material is selected as the peptizer. Control Example 24: AgIBr (3 mol% I) Nontabular Grain Emulsion Prepared with Noncationic Polysaccharide Dextran Polysaccharide Dextran with a Molecular Weight of about 500,000 (Sigma Chemical, St. Louis, Mo.)
The emulsion of this example was prepared in the same manner as in Example 2 except that (available from Al Co., Ltd.) was used.

Precipitation produced large agglomerates of tabular grains. Dextran was unable to deflocculate silver halide grains. Control Example 25: AgIBr (3 mol% I) non-tabular grain emulsion prepared with non-cationic polysaccharide agar The polysaccharide used was agar (purified product, ash <2%, Sigma
a Chemical product) was prepared in the same manner as in Example 2 to prepare the emulsion of this example.

The precipitation produced tabular grains which separated into large lumps. Agar was a poor peptizer for silver halide grains. Control Example 26: AgIBr (3 mol% I) non-tabular grain emulsion prepared with non-cationic polysaccharide pectin The polysaccharide used was pectin (Si from citrus fruit).
The emulsion of this example was prepared in the same manner as in Example 2 except that it was obtained from Gma Chemical Co.).

A non-tabular grain emulsion was obtained. Control Example 27: AgIBr (3 mol% I) non-tabular grain emulsion prepared with non-cationic polysaccharide gum arabic The polysaccharide used was gum arabic with a molecular weight of about 250,000 (obtained from Sigma Chemical Company). The emulsion of this example was prepared in the same manner as in example 2 except for the above.

A non-tabular grain emulsion was obtained. Controls 28-30 These examples confirm that the above experimental conditions for making tabular grain emulsions with cationic starch do not work well with gelatin. Gelatin is a well-known peptizer used for precipitation of tabular grain emulsions, but if all of the peptizers are added before the grain nucleation shown above using cationic starch, precipitation of tabular grain emulsions occurs. Was hampered. Control Example 28: AgIBr (3 mol% I) tabular grain emulsion prepared using gelatin as a peptizer This example emulsion was prepared in the same manner as in Example 2 except that oxidized bone gelatin was used instead of starch. Was prepared.

The tabular grain population of the resulting emulsion was comprised of tabular grains having an average equivalent circular diameter of 2.2 μm, an average thickness of 0.07 μm and an average aspect ratio of 31. The tabular grain population is 60% of the total projected area of the emulsion grains.
(Lower than 85% in Example 2). Control Example 29: AgIBr (3 mol% I) non-tabular grain emulsion prepared using gelatin as a deflocculating agent. The emulsion of this example was prepared.

The tabular grain population of the resulting emulsion was composed of tabular grains having an average equivalent circular diameter of 2.0 μm, an average thickness of 0.06 μm and an average aspect ratio of 33. Tabular grain population is 30% of total projected area of emulsion grains
Only occupied. Control Example 30: AgBr non-tabular grain emulsion prepared using gelatin as a peptizer Example except that oxidized bone gelatin was used instead of starch and the precipitation growth temperature was 60 ° C instead of 50 ° C. This Example emulsion was prepared in the same manner as in 2.

The tabular grain population of the resulting emulsion was comprised of tabular grains having an average equivalent circular diameter of 3.2 μm, an average thickness of 0.07 μm and an average aspect ratio of 46. Tabular grain population is 30% of total projected area of emulsion grains
Only occupied. Control Example 31: AgIBr (2.7 mol% I) Tabular Grain Emulsion The tabular grain thickness is equal to or less than the tabular grain emulsion precipitated with the cationic starch described in Example 1 and the tabular grains are the same. The emulsion of this example was prepared in bone gelatin using the usual procedure preferred to form tabular grain emulsions to provide emulsions of equal or small projected area.

The emulsion was diafiltration washed to a pBr of 3.38 at 40 ° C. The tabular grains had an average equivalent circular diameter of 2.45 μm, an average thickness of 0.06 μm, and an average aspect ratio of 41. The tabular grain population accounted for 95% of the total projected area of the emulsion grains. Table 1 Summary of emulsions ─────────────────────────────────── Total grain projection plane Occupy in tabular area Example Nitrogen Phosphorus tabular grain tabular grains (control) Peptizer Cation (wt%) (wt%) Presence rate (%) 1 Potato starch Yes 0.33 0.13 ^a Yes 92 2 Hybrid corn de Yes 0.31 0.00 Yes 85 Numbung 3 Potato Starch Yes 0.36 0.70 Yes 95 4 Potato starch Yes 0.36 0.70 Yes 95 5 Potato starch Yes 0.33 0.13 ^a Yes 80 6 Waxy corn Yes 0.36 0.06 ^a Yes 91 Starch 7 Potato starch Yes 0.33 0.13 ^a Yes 90 8 Potato starch Yes 0.34 1.15 Yes 80 9 Potato starch Yes 0.33 0.13 ^a Yes 85 10 Corn starch Yes Yes 0.25 0.03 ^a Yes 55 11 Potato starch Yes 0.33 0.13 ^a Yes 80 12 Corn starch Yes 0.26 0.00 Yes 65 13 Corn starch Yes 0.15 0.00 Yes 60 14 Wheat starch Yes 0.41 ^b 0.07 ^a Yes 85 15 Potato starch Yes 0.33 0.13 ^a Yes 70 16 Potato starch Yes 1.10 0.25 ^a Yes 80 17 Potato starch Yes 0.33 0.13 ^a Yes 85 (18) Corn starch No 0.06 ^a 0.00 No 0 (19) Potato starch None 0.03 ^a 0.66 None 0 (20) Corn starch None 0.06 ^a 0.00 None 0 (21) Potato starch None 0.04 ^a 0.06 None 0 (22) Wheat starch None NM NM None 0 (23) Zein None NM NM NM No 0 (24) Dextran No NM NM No 0 (25) Agar No NM NM No 0 (26) Pectin No NM NM No 0 (27) Gum Arabic No NM NM No 0 (28) Gelatin NA NA NA Yes 60 (29) ) Gelatin NA NA NA Yes 30 (30) Gelatin NA NA NA Yes 30 (31) Gelatin NA NA NA Yes 95 a: Natural component b: Calculated from the degree of substitution NM: Not measured NA: Not applicable Example 32: Senshi Totometry comparison 4 emulsions The samples were compared.

The tabular grain emulsion of Example 1 precipitated in the presence of cationic starch was divided into 3 parts to give 3 samples. The two parts were not further processed until sensitized ("Example 1 STA" and "Example 1 STA-Spectral"). The samples were identical, but the latter sample was only spectrally sensitized instead of chemically and spectrally sensitized, like the rest of the emulsion samples.

Third Part "Example 1 GEL" (0.8
(1 mol) was added with 20 g of bone gelatin added to 100 ml of distilled water. The purpose of adding gelatin was to show the effect of gelatin added as a vehicle after precipitation as usual and before chemical sensitization. A fourth emulsion sample was deposited on bone gelatin using conventional silver iodobromide (2.7
Mol% I) tabular grains (Control 31). The purpose of this sample was to compare the properties of emulsions precipitated in the presence of gelatin to emulsions precipitated in the absence of gelatin and sensitized in the presence or absence of gelatin.

An emulsion sample of 0.035 mol (see Table II below) was stirred at 40 ° C. with stirring at 2.5 mmol / mol A.
g NaSCN, 0.22 mmol / mol Ag benzothiazolium salt, 1.5 mmol / mol Ag anhydro-5,5′-dichloro-3,3′-bis (3-sulfopropyl) thiacyanine hydroxy. And triethylammonium salt and 0.08 mmol / mol Ag 1- (3
A solution containing -acetamidophenyl) -5-mercaptotetrazole and sodium salt was added sequentially. pH
Was adjusted to 5.9. Then, 0.023 mmol / mol Ag of 2-propargylaminobenzoxazole,
0.036 mmol / mol Ag of 1,3-dicarboxymethyl-1,3-dimethyl-2-thiourea and 0.0
A solution of 14 mmol / mol Ag of bis (1,3,5-trimethyl-1,2,4-triazolium-3-thiolate) gold (I) tetrafluoroborate was added sequentially. The mixture is heated to 55 ° C. at a heating rate of 5 ° C./3 minutes, 5
Hold at 5 ° C for 15 minutes. After cooling to 40 ° C., a solution of 5-bromo-4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene 1.68 mmol / mol Ag was added. Example 1 Only for STA-Spectral,
Spectral sensitizing dye was added. The sensitized emulsion thus obtained was mixed with gelatin, a yellow dye-forming coupler dispersion, a surfactant and a hardener to give 0.84 g / m 2 on a transparent support.
Coated with ² silver, 1.7 g / m ² yellow dye forming coupler and 3.5 g / m ² bone gelatin.

The coating was exposed to blue light for 0.02 seconds through a 0-4.0 log density graduated step tablet and processed in a Kodak Flexicolor C-41, color negative process with a development time of 3 minutes and 15 seconds. The results are summarized in Table II. Table II ───────────────────────────── emulsion sensitized 0.2 than midscale Dmin D _max D _min relative sensitivity on contrast Control Example 31 3.03 0.08 2.01 100 Example 1 GEL 2.86 0.09 1.79 115 Example 1 STA 3.18 0.13 2.08 204 Example 1 0.70 0.05 1.69 -11 STA-Spectral Control Example 31 (Normal particles precipitated in the presence of gelatin) Tabular grain emulsions) were used as a sensitivity standard. The Example 1 GEL precipitated in the presence of cationic starch, but with gelatin added prior to chemical sensitization, showed a sensitivity of 15 relative sensitivity units higher than that of Control Example 31. That is, Example 1 GEL had 0.15 log E (1
5 Relative sensitivity unit = 0.15 log E (where, E was high in exposure amount (unit: lux · second). This is advantageous in terms of sensitivity of 0.15 log E (1/2 stop)). Unlike gelatin, it was unexpected that precipitation in the presence of cationic starch would provide this significant sensitivity advantage.

Quite surprisingly, Example 1 STA gave a great advantage in terms of sensitivity. This emulsion, precipitated and sensitized in the absence of gelatin, was 1.04 log E higher than Control Example 31. In other words, it was 10 times faster than the regular Control 31 emulsion. Example 1 STA-Spectral was used to show that, apart from the chemical sensitizer, the cationic starch itself does not impart the observed sensitivity. Example 1 STA-
Spectral was 111 relative sensitivity units (1.11 log E) lower than Control 31. From this it can be concluded that cationic starch has in some respects a better interaction between the chemical sensitizer and the grain surface than is normally achieved by using gelatin as a peptizer. Example 33: Testing of Starch Retained After Washing A coating of Example 1 STA prepared by the method described in Example 32 was coated with an active proteolytic enzyme (Miles Labs HT Co., Elkhart, IN). -Pr
The gelatin was decomposed by treatment with a 0.2 wt% solution of oteolytic 200) at 35 ° C. for 30 minutes. The emulsion grains were washed twice with distilled water and investigated by infrared spectrophotometry. The infrared absorption spectrum of the starch was clearly observed and it was found that the starch remained in the constant part of the emulsion and was not removed by washing. Example 34: Peptizer Viscosity Comparison CS STA-LOK (TM) 400 8g and NaBr2.
A 2 wt% cationic starch solution (CS) was prepared by boiling a mixture of 7 mmol and distilled water in an amount necessary to make the whole 400 ml with stirring for 30 minutes. The solution was sonicated for 3 minutes. The resulting solution was cooled to 40 ° C., readjusted to 400 ml with distilled water, sonicated for 3 minutes and adjusted to pH 6.0.

GEL 2% by weight gelatin solution (GEL) using bone gelatin
Was prepared. To this 4 liters, 27 mmol of NaBr was added and the pH was adjusted to 6.0 at 40 ° C. Water, CS
The kinematic viscosity of the solution and the GEL solution were measured at various temperatures. The results are shown below.

[0119] X = Unable to test because the solution solidified.

The viscosity data show that the cationic starch had a low viscosity at low temperatures, while the gelatin solution solidified. For this reason, cationic starch is particularly useful for silver halide grain nucleation and / or growth at temperatures below 25 ° C. Examples 35-44C These examples demonstrate the benefits obtained by using oxidized cationic starch as a peptizer. The subscript “C” is used to indicate that the comparative example does not satisfy the requirements of the present invention. The acronyms "OCS", "CS" and "GEL" are used to indicate oxidized cationic starch (OCS), non-oxidized cationic starch (CS) and gelatin (GEL).

Preparation of Oxidized Cationic Starch The mixture of 80 g of OCS-1 cationic potato starch, 27 mmol of NaBr, and distilled water in an amount necessary to bring the total amount to 4 liters was boiled for 30 minutes while stirring to give the oxidized cation starch. A starch solution (OCS-1) was prepared. Starch (STA-LOK ™ 400) is an A. E. FIG. Staley Ma
Obtained from Nufacturing, a mixture of 21% amylose and 79% amylopectin, 0.33% by weight nitrogen in the form of a quaternary trimethylammonium alkyl starch ether and 0.13% natural phosphorus.
It was a weight% and the average molecular weight was 2200000.

The resulting solution was cooled to 40 ° C., readjusted to 4 liters with distilled water and the pH was adjusted to 7.9 with solid NaHCO ₃ (1.2 g required). While stirring
Dilute H with 50 ml of NaOCl solution (containing 5% by weight of chlorine)
The pH was maintained at 6.5-7.5 by addition with NO _3. Then the pH was adjusted to 7. with saturated NaHCO ₃ solution.
Adjusted to 75. The stirred solution was heated at 40 ° C. for 2 hours. The pH of this solution was adjusted to 5.5. Comparison of Peptizer Viscosity A 2 wt% solution of oxidized cationic starch (OCS-2) was prepared in the same manner as above except that the final pH of the OCS-2 solution was adjusted to 6.0 (instead of 5.5). did.

CS-1 STA-LOK ™ 400 8 g and NaBr2.
A 2 wt% solution of cationic starch (CS-1) was prepared by boiling a mixture of 7 mmol and distilled water in an amount necessary to bring the total to 400 ml with stirring for 30 minutes. The resulting solution is cooled to 40 ° C. and distilled water to 4
Readjust to 00 ml, sonicate for 3 minutes, adjust pH to 6.0
Was adjusted.

GEL-1 A 2% by weight gelatin solution (GEL-
1) was prepared. To this 4 liters, 27 mmol of NaBr was added and the pH was adjusted to 6.0 at 40 ° C. The kinematic viscosities of these three solutions were measured at various temperatures. The results are shown in Table IV.

[0125] X: The solution solidified.

The viscosity data show that the oxidized cationic starch has the lowest viscosity at low temperatures (below about 25 ° C.). Due to this low viscosity, nucleation of silver halide grains and / or
Alternatively, it is desirable to grow at a temperature below 25 ° C. Example 35: AgIBr (3 mol% I) Ultrathin Tabular Grain Emulsion Prepared Using Oxidized Cationic Potato Starch 4 liters of oxidized cationic starch solution (OCS-1) are placed in a reaction vessel and vigorously stirred at 35 ° C. While 2M
AgNO ₃ solution was added at 100 ml / min for 0.2 minutes. At the same time, 1.94M NaBr and 0.06M K
The salt solution of I was added initially at 100 ml / min and then at the flow rate required to maintain pBr at 2.21. After that, the addition of the solution was stopped, and 25 ml of 2M NaBr solution was added.
Is added rapidly to raise the temperature of the contents of the reaction vessel to a heating rate of 5
The temperature was raised to 60 ° C in 3 ° C / 3 minutes. AgNO at 60 ° C
After adding ₃ solutions at 10 ml / min for 1 minute, change the flow rate to 30
After accelerating to 40 ml / min in minutes, this rate was maintained until the total silver addition amount was 2 mol. Iodide-containing salt solution,
Simultaneous additions were made at the rate required to maintain a constant pBr of 1.76. The resulting tabular grain emulsion was washed by diafiltration at 40 ° C. to give pBr 3.38.

Tabular grains have a mean equivalent circular diameter (ECD)
It contained tabular grains having a thickness of 1.1 μm, an average thickness of 0.05 μm, and an average aspect ratio of 22. The tabular grain population accounted for 95% of the total projected area of the emulsion grains. The diameter variation coefficient of the emulsion grains was 21%. Example 36: Using oxidized cationic starch and pBr
AgIBr (3 mol% I) ultrathin tabular grain emulsion grown at 2.0 400 g of oxidized cationic starch solution (OCS-1) was placed in a reaction vessel, and 2M AgNO was added with vigorous stirring at 35 ° C. and pH 6.0. _{The 3} solutions were added at a constant rate of 10 ml / min. At the same time, 1.94M NaBr and 0.06M
KI salt solution was initially added at 10 ml / min and then pBr
Was added at the flow rate required to maintain 2.21. 0.
After 2 minutes, the addition of the solution was stopped and the 2M NaBr solution 2.
5 ml was quickly added, and the temperature of the contents of the reaction vessel was raised to 60 ° C at a heating rate of 5 ° C / 3 minutes. pH 6.0
And kept at this value for the rest of the precipitation. At 60 ° C,
AgNO ₃ solution was added at 1.0 ml / min, and the salt solution was added at the rate required to maintain a pBr of 1.76. After performing precipitation for 3 minutes with this pBr, the inflow of the salt solution was stopped until pBr reached 2.00. Next, the flow rate of the AgNO ₃ solution was adjusted so that the total amount of silver added was 0.
It was accelerated to a rate of 20 ml which would reach 4 ml / min in 60 minutes. The iodide-containing salt solution was added to pBr
It was added at the rate needed to hold it at 2.00.

The tabular grain population of the resulting emulsion was composed of ultrathin tabular grains having an average equivalent circular diameter of 1.7 μm, an average thickness of 0.055 μm and an average aspect ratio of 31. The tabular grain population accounted for 95% of the total projected area of the emulsion grains. Example 37: AgIBr (3 mol% I) ultrathin tabular grain emulsion In the same manner as described in Example 36, except that the precipitation was stopped after the total amount of the AgNO ₃ solution added reached 0.10 mol. The emulsion of this example was prepared.

The tabular grain population of the resulting emulsion was comprised of ultrathin tabular grains having an average equivalent circular diameter of 1.2 μm, an average thickness of 0.040 μm and an average aspect ratio of 30. The tabular grain population accounted for 95% of the total projected area of the emulsion grains. Example 38: Using oxidized cationic starch and pBr
AgIBr (3 mol% I) ultrathin tabular grain emulsion grown at 1.5 400 g of oxidized cationic starch solution (OCS-1) was placed in a reaction vessel and stirred at 35 ° C. and pH 6.0 with 2M AgNO. _{The 3} solutions were added at a constant rate of 10 ml / min. At the same time, 1.94M NaBr and 0.06M
KI salt solution was initially added at 10 ml / min and then pBr
Was added at the flow rate required to maintain 2.21. 0.
After 2 minutes, the addition of the solution was stopped and the 2M NaBr solution 2.
5 ml was quickly added, and the temperature of the contents of the reaction vessel was raised to 60 ° C at a heating rate of 5 ° C / 3 minutes. pH 6.0
And kept at this value for the rest of the precipitation. At 60 ° C,
AgNO ₃ solution was added at 1.0 ml / min, and the salt solution was added at the rate required to maintain a pBr of 1.76. After performing precipitation for 3 minutes with this pBr, the inflow of silver and salt solutions was stopped, and 2.0M NaBr solution 2.75 was added.
ml was added. Next, the flow rate of the AgNO ₃ solution was changed to 4 m in 60 minutes until the total amount of silver added reached 0.20 mol.
Accelerated at a speed that would reach 1 / min. The iodide-containing salt solution was added at the rate required to maintain pBr1.5.

The tabular grain population of the resulting emulsion was composed of ultrathin tabular grains having an average equivalent circular diameter of 3.0 μm, an average thickness of 0.05 μm and an average aspect ratio of 60. The tabular grain population is 9% of the total projected area of the emulsion grains.
It accounted for 5%. Example 39: AgIBr (3 mol% I) Ultrathin Tabular Grain Emulsion The same as described in Example 38 except that the precipitation was stopped after the total amount of the AgNO ₃ solution added reached 0.10 mol. The emulsion of this example was prepared.

The tabular grain population of the resulting emulsion was comprised of ultrathin tabular grains having an average equivalent circular diameter of 1.5 μm, an average thickness of 0.040 μm and an average aspect ratio of 38. The tabular grain population accounted for 98% of the total projected area of the emulsion grains. Example 40: AgIBr (3 mol% I) Ultrathin Tabular Grain Emulsion Prepared by Low Temperature Grain Nucleation Using Oxidized Cationic Starch 400 g of oxidized cationic starch solution (OCS-1) was placed in a reaction vessel at 13 [deg.] C, pH6. vigorous stirring in 2.0, was added 2M AgNO ₃ solution at a constant rate 10 ml / min. At the same time, 1.94M NaBr and 0.06M
KI salt solution was initially added at 10 ml / min and then pBr
Was added at the flow rate required to maintain 2.21. 0.
After 2 minutes, the addition of the solution was stopped and the 2M NaBr solution 2.
5 ml was rapidly added, and the temperature of the contents of the reaction vessel was raised to 50 ° C at a heating rate of 5 ° C / 3 minutes. pH 6.0
And kept at this value for the rest of the precipitation. At 50 ° C
AgNO ₃ solution was added at 1.0 ml / min, and the salt solution was added at the rate required to maintain a pBr of 1.76. After performing precipitation with this pBr for 3 minutes, AgNO
The flow rate of solution ₃ was accelerated to 4 ml / min in 60 minutes and kept at this rate until the total amount of silver added was 0.40 mol. The iodide-containing salt solution was added at the rate required to maintain a pBr of 1.76.

The resulting tabular grain population of the ultrathin tabular grain emulsion had an average equivalent circular diameter of 1.8 μm and an average thickness of 0.06.
It contained ultra-thin tabular grains having a micrometer and an average aspect ratio of 30. The tabular grain population accounted for 95% of the total projected area of the emulsion grains. Example 41: AgIBr (3 mol% I) ultrathin tabular grain emulsion prepared by low temperature grain nucleation using oxidized cationic starch, except that precipitation was stopped after the total amount of silver added reached 0.20 mol. The emulsion of this example was prepared in the same manner as in Example 40.

The tabular grain population of the resulting emulsion comprised ultrathin tabular grains having an average equivalent circular diameter of 1.3 μm, an average thickness of 0.045 μm and an average aspect ratio of 29. The tabular grain population accounted for 98% of the total projected area of the emulsion grains. Example 42: AgIBr (3 mol% I) Ultrathin Tabular Grain Emulsion Prepared by Low Temperature Grain Nucleation Using Oxidized Cationic Starch Precipitation was stopped after the total amount of AgNO ₃ solution was 0.10 mol. The emulsion of this example was prepared in the same manner as in Example 40 except that the above was performed.

The tabular grain population of the resulting emulsion was comprised of ultrathin tabular grains having an average equivalent circular diameter of 1.0 μm, an average thickness of 0.040 μm and an average aspect ratio of 25. The tabular grain population accounted for 98% of the total projected area of the emulsion grains. Example 43: AgIBr (3 mol% I) Ultrathin Tabular Grain Emulsion Prepared by Low Temperature Grain Nucleation Using Oxidized Cationic Starch Precipitation was stopped after the total amount of AgNO ₃ solution added reached 0.05 mol. The emulsion of this example was prepared in the same manner as in Example 40 except that the above was performed.

The average thickness was measured by scanning 195 tabular grains using atomic force microscopy to obtain the average tabular grain + adsorbed starch thickness. Measured starch thickness 0.
0030 μm (sum of both sides) was subtracted from this value. The corrected average thickness was 0.034 μm. The area-weighted equivalent circular diameter was 0.70 μm. The average aspect ratio was 21. The tabular grain population accounted for 98% of the total projected area of the emulsion grains. Example 44C: AgI with oxidized non-cationic starch
Attempts to Prepare Br (3 mol% I) Ultrathin Tabular Grain Emulsions The starch used was Sigma, St. Louis, MO.
a Emulsion of this example was prepared in the same manner as in Example 38 except that it was a soluble potato starch obtained from Chemical Company. The starch was oxidized using a method similar to that used for the starch of Example 38.

An agglomerate of three-dimensional particles was obtained. No tabular grains or separate three-dimensional grains were observed. This oxidized non-cationic starch has high bromide ion concentrations commonly used to make tabular grain emulsions, especially Example 3
Bromide concentration (pBr
= 1.5), the silver halide grains could not be released. Example 45: Sensitometric comparison The purpose of this example is to show the effect of various peptizers and peptizer combinations on photographic performance.

Emulsions were prepared by selecting five kinds of peptizers to be introduced before chemical sensitization. GEL only Control 31 emulsion was used. Gelatin was the only peptizer present before chemical sensitization. CS + GEL Example 1 emulsion was used. Non-oxidized cationic starch (CS) was present at the time of precipitation. Before chemical sensitization, 25 g of bone gelatin was added per mol of silver.

CS only The emulsion of Example 1 was used. Prior to chemical sensitization, only non-oxidized cationic starch (CS) was present. OCS + GEL The Example 35 emulsion prepared using oxidized cationic starch as a peptizer was modified by adding 25 g of bone gelatin per mole of silver before chemical sensitization.

OCS Only The Example 35 emulsion was used. Prior to chemical sensitization, only oxidized cationic starch (OCS) was present. Chemical sensitization 0.035 mol of emulsion sample (see Table IV below) at 40 ° C
With stirring at 2.5 mmol / mol Ag NaSCN, 0.22 mmol / mol Ag benzothiazolium salt, 1.5 mmol / mol Ag anhydro-.
5,5'-dichloro-3,3'-bis (3-sulfopropyl) thiacyanine hydroxide, triethylammonium salt and 0.08 mmol / mol Ag 1- (3-acetamidophenyl) -5-mercaptotetrazole,
The solution containing the sodium salt was added sequentially. The pH was adjusted to 5.9. Next, 0.023 mmol / mol A
g 2-propargylaminobenzoxazole (reduction sensitizer with R in Table IV below), 0.036 mmol / mol Ag 1,3-dicarboxymethyl-1,3
-Dimethyl-2-thiourea (sulfur sensitizer with S in Table IV below) and 0.014 mmol / mol Ag
Of a solution of bis (1,3,5-trimethyl-1,2,4-triazolium-3-thiolate) gold (I) tetrafluoroborate (Au-sensitized gold sensitizer in Table IV below). The combinations were added sequentially. The mixture was heated to a temperature shown in Table IV below at a heating rate of 5 ° C./3 minutes,
Hold at this temperature for 15 minutes. Cool to 40 ° C.,
Bromo-4-hydroxy-6-methyl-1,3,3a,
A solution of 7-tetraazaindene 1.68 mmol / mol Ag was added.

The blue spectral / chemically sensitized emulsion thus obtained was mixed with gelatin, a yellow dye-forming coupler dispersion, a surfactant and a hardener to give 0.84 g / m 2 on a transparent support.
Coated with ² silver, 1.7 g / m ² yellow dye forming coupler and 3.5 g / m ² bone gelatin. 0 to the coating film
Exposure to blue light for 0.02 seconds through a 4.0 log density graduated step tablet, Kodak Flexi
Color C-41 was developed in a color negative process with a development time of 3 minutes and 15 seconds.

The results are summarized in Table V. GEL O
The NLY sample (S + Au + R sensitized at 55 ° C.) was used as a sensitivity standard, and the relative sensitivity measured at a density 0.2 higher than the minimum density (Dmin) was set to 100. Relative sensitivity 10
Each relative sensitivity unit difference between 0 and the stated relative sensitivity is 0.
01logE (where E is the exposure dose (unit: lux / second)
). For example, CS + GEL is GEL O
An exposure dose of 0.15 log E less was required to reach a reference density of 0.2 above Dmin above NLY.

Table V Ultrathin Tabular Grain Emulsion Sensitization ─────────────────────────────── Central Scale Sensitization Temperature Rucon Sample Sensitizer (℃) Dmax Dmin Trust Relative sensitivity GEL only S + Au + R 55 3.03 0.08 2.01 100 CS + GEL S + Au + R 55 2.86 0.09 1.79 115 CS + GEL S + Au + R 65 3.12 0.12 1.95 198 CS only S + Au 45 1.03 0.04 1.70 12 CS only S + Au + R 45 1.55 0.05 1.71 46 CS only S + Au + R 55 3.18 0.13 2.08 204 OCS + GEL S + Au 45 1.73 0.05 2.58 23 OCS + GEL S + Au + R 45 1.93 0.05 2.40 37 OCS only S + Au 45 3.09 0.14 2.05 192 OCS only S + Au 50 3.13 0.21 2.01 203 Table V shows that after sensitization, at relatively low temperatures (45 ° C and 50 ° C) and 2-propargyl. The photographic sensitivity of OCS ONLY sensitized without aminobenzoxazole (R) is higher than that of other emulsions sensitized at the same low temperature.
Was much better even when was added to increase sensitivity. GELONLY, CS + due to the presence of gelatin
The effective sensitizing ability of GEL and OCS + GEL was significantly inhibited. Only by using higher temperatures for chemical sensitization did these control emulsions approach the photographic speed of OCS ONLY sensitized at 45 ° C and 50 ° C. S +
OCS ONLY sensitized with Au at 45 ° C. was 1.8 log E higher than similarly sensitized CS ONLY. This indicates that lower sensitization temperatures can be employed with oxidized cationic starch as the only peptizer.

It was found that when these ultrathin tabular grains were sensitized at a temperature above 50 ° C., the grain thickness was remarkably increased. In the ultrathin tabular grain emulsion of Example 1 above,
Both OCS and OCS + GEL were used. The average thickness of the ultrathin tabular grains before chemical sensitization was 0.050 μm. A comparison of average ultrathin tabular grain thickness before and after chemical sensitization for 15 minutes at various temperatures is summarized in Table VI below.

[0144] N. A. = Not applicable, thickness is the thickness before chemical sensitization.

Table VI shows OCS ONLY at 45 ° C., 5
Sensitization at 0 ℃ and 55 ℃ and OCS + GEL 65 ℃
The results of sensitization are shown below. About OCS + GEL, 65
A temperature of ° C was chosen. This is due to the lowest chemical sensitization temperature observed to obtain sensitivity levels comparable to OCS ONLY. After chemical sensitization at 65 ° C., the average thickness of the tabular grains obtained is no longer than <0.07 μm, ie
It wasn't very thin anymore. Therefore, the advantage of ultrathin tabular grain emulsion thickness has been lost. Examples 46-48 These examples demonstrate the performance of emulsions in radiographic film constructions. Example 46 Emulsion A (SXR) Chemical Sensitization 0.035 mol of the emulsion of Example 1 was stirred therein at 40 ° C. while adding 2.5 mmol / mol Ag NaSCN,
Benzothiazolium salt of 0.22 mmol / mol Ag,
1.5 mmol / mol Ag anhydro-5,5'-dichloro-3,3'-bis (3-sulfopropyl) thiacyanine hydroxide, triethylammonium salt and 0.08 mmol / mol Ag 1- (3. A solution containing -acetamidophenyl) -5-mercaptotetrazole and sodium salt was added sequentially. The pH was adjusted to 5.9. Next, 0.023 mmol / mol Ag of 2-propargylaminobenzoxazole and 0.036 mmol / mol Ag of 1,3-dicarboxymethyl-1,3-.
Dimethyl-2-thiourea and 0.014 mmol / mol Ag of bis (1,3,5-trimethyl-1,2,4-
A solution of triazolium-3-thiolate) gold (I) tetrafluoroborate was added sequentially. The mixture was heated to 55 ° C at a heating rate of 5 ° C / 3 minutes and held at this temperature for 15 minutes. After cooling to 40 ° C., a solution of 5-bromo-4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene 1.68 mmol / mol Ag was added.

Film Coatings Coatings AI Nati, Bridgewater, NJ
Anionic starch FILMKOTE ™ 54, obtained from onal Starch and Chemical Company, is approximately 25% amylose and 7 amylopectin.
Corn starch consisting of 5% and treated with octenyl succinic anhydride.

To 2 g of FILMKOTE ™ 54 was added 19 g of distilled water and the mixture was boiled for 30 minutes with stirring. Weight was returned to 21 g. pH at 40 ° C 5.
Adjusted to 9. Thereafter, Emulsion A (SXR) 5.8 mmol, bis (vinylsulfonyl) methane hardener 0.16 g
The containing solution, surfactant and distilled water required to bring the total to 42 g were added. The mixture was hand coated onto a gelatin subbed cellulose acetate film support with an expected laydown of 1.5 g silver / m ² and 4.3 g / m ² starch. No gelatin was present in the emulsion layer.

Coating film AII 5% bone gelatin solution 20 adjusted to pH 5.9 at 40 ° C. 20
To g, 5.8 mmol of Emulsion A (SXR), a solution containing 0.036 g of a bis (vinylsulfonyl) methane hardener, a surfactant, and distilled water in an amount necessary for bringing the total amount to 42 g were added. The mixture was coated by hand on a cellulose acetate film support with an expected coat weight of 1.5 g / m ² silver and 4.3 g / m ² gelatin.

Comparison of sensitometry After being stored for 2 weeks and acted with a hardener, the coating film AI and the coating film AII were white for 0.02 seconds through a 0-4.0 density graduated TESUP tablet. Exposed to light. The exposed film was processed as follows using a commercial Kodak RP X-Omat rapid processor: Development 2 at 40 ° C.
Fixing at 40 ° C. for 12 seconds, washing at 40 ° C. for 8 seconds and drying at 65 ° C. for 20 seconds.

The coating film AI has Dmax of 1.08 and Dmin.
It was 0.37, relative sensitivity (above Dmin of 0.2) 89, and intermediate scale contrast 0.51. Coating film A
II was Dmax 1.81, Dmin 0.68, relative sensitivity (0.2 above Dmin) 100, and intermediate scale contrast 0.52. Comparison of image color tone The color tone of the silver image obtained by exposing and processing the radiographic element was evaluated by the following method.

The visible transmitted light absorption spectrum was analyzed by Hitac
hi Model U-3410 spectrophotometer (Hitachi Instru, Danbury, CT)
(commercially available from Ments, Inc.) was used to record through a silver image area of uniform optical density. Next, the color of each region is determined by comparing the energy spectrum of the sample with a constant light and CIE.
(Commission International
de l'Eclairage or Intern
national Commission on Illu
mination) was defined by calculating CIE tristimulus values in combination with the standard color function. Standard illuminant used was the CIE light D _{6 5} representing an average daylight. CIE LAB values of b ^* were obtained by mathematical transformation.

B^*The values indicate a yellow-blue balance, warm
Or, it is a good measure of cold image tone. b ^*Change of about 0.7
Is generally detectable when observed with the unaided human eye.
Acceptable as a discrimination threshold. b^*Increase in positive value of
Is that the temperature control (yellow hue) of the image is increased.
b^*Negative value shifts and negative value increases
Tone (blue hue) shift to silver image or cold tone (blue color)
Phase) shows a silver image.

Tonal value (b ^* ) obtained for each coating
Was measured at a density of 1.0 on the film sample. The results are summarized in Table VII. From the b ^* values shown in Table VII, the film coating using starch as the vehicle only had a much better image tone than the coating using gelatin as the binder part of the vehicle.

From the 1500 times optical micrograph of the low density portion of the image, the developed silver of the coating AI had a rod-like to thread-like shape, while the developed silver of the coating AII had a spherical to irregular shape. It was considered that the difference in color tone of the image was observed due to this difference in shape. Example 47 Emulsion-hardener mixture mixed with gelatin-coated Esta
This example was carried out in the same manner as the coating film AI except that the expected coating amount of silver of 3.0 g / m ² and starch of 8.6 g / m ² were manually coated on both surfaces of the r (trademark) poly (ethylene terephthalate) film support. An example coating was created. No gelatin was present in the emulsion layer.

The obtained double coated radiographic film was
It was exposed and processed as in Example 48. The color tone value b ^* obtained by measuring at a density of 1.0 was 2.44. Example 48 Emulsion B: AgBr Tabular Grain Emulsion Prepared with Cationic Potato Starch 40 g of STA-LOK (TM) 400 and NaBr2.
A cationic starch solution was prepared by boiling a mixture of 7 millimoles and distilled water in an amount necessary to bring the total to 4 liters for 30 minutes with stirring. The resulting solution was cooled to 35 ° C., readjusted to 4 liters with distilled water, and the pH adjusted to 6.0.

Add the starch solution at 35 ° C. to the reaction vessel
While stirring vigorously, 2.0M AgNO was added there._ThreeDissolution
The liquid was added at 100 ml / min for 0.2 minutes. at the same time,
Add 2.5M NaBr solution at 100 ml / min first
Then added at the flow rate required to maintain pBr at 2.21.
did. Then the solution addition was stopped and 2.0 M NaBr was added.
Add 25 ml of solution rapidly and adjust the temperature of the contents of the reaction vessel.
Was raised to 60 ° C. at a heating rate of 5 ° C./3 minutes. pH
It was adjusted to 6.0 and kept at this value for the duration of precipitation. 6
AgNO at 0 ° C_ThreeAdd the solution at 10 ml / min, 2.
Required to maintain 5M NaBr solution at pBr 1.76.
It was added at the required rate. Precipitation was carried out for 3 minutes with this pBr
Then, the inflow of the 2.5M NaBr solution was changed to pBr of 2.00.
It stopped until it reached. AgNO_ThreeStop adding solution
, STA-LOK (trademark) 40040 g, and NaBr
10 millimoles and the amount necessary to make 1 liter
A solution consisting of distilled water is boiled at 60 ° C for 30 minutes to react.
Added to container. AgNO _ThreeFlow rate of solution is 10ml / min
Restart at, accelerate to 40 ml / min in 60 minutes, and then A
gNO_ThreeDo this until the total amount of solution added reaches 2 liters.
Flow rate was maintained. NaBr solution, pBr 2.00
Was added at the rate required to maintain. Next, AgNO
_Three10m until the solution reaches pBr of 3.04
After adding at 1 / min, add NaBr solution at the same time.
PBr was maintained for 20 minutes. The total amount of silver added is 4.53
Mole was added.

The resulting tabular grain emulsion was washed by diafiltration at 40 ° C. The tabular grains had an average equivalent circular diameter of 1.3 μm, an average thickness of 0.08 μm, and an average aspect ratio of 16. The tabular grain population accounted for 95% of the total projected area of the emulsion grains. Emulsion B (SX): Chemical Sensitization Emulsion B was chemically sensitized and spectrally sensitized to green light.
For sensitization, potassium tetrachloroaurate, sodium thiocyanate, sodium thiosulfate, potassium selenocyanate, 350 mg / Ag mol of potassium iodide and anhydro-5,5′-dichloro-9-ethyl-3,3′-diamine. −
(3-Sulfopropyl) oxacarbocyanine hydroxide and triethylamine salt were used.

Coating of film Coating BI was formed in the same manner as coating AI except that Emulsion B (SX) was used. No gelatin was present in the emulsion layer. Coating BII A coating was formed in the same manner as Coating AII except that Emulsion B (SX) was used.

Image Tone Comparison These two thin coatings were exposed and processed in the same manner as Coatings AI and AII. The obtained tone value b ^* is
The film samples were measured at a density of 0.9. The result
Shown in Table VIII. Table VIII ──────────────── Coating Film Coating Vehicle b * BI Starch 1.22 BII Gelatin 2.47 As can be seen from Table VIII, the b ^* values are shown in Table VI. Smaller than listed. All other matters being equal, the thicker the tabular grain emulsion, the lower the b ^* value (the better the X-ray image color tone).
The emulsion coated with starch as the sole vehicle (Coating BI) had a significantly lower b ^* value (improved image tone) than when coated with the same emulsion with gelatin present as a binder.

The preferred embodiments of the present invention will be described below item by item. (1) A transparent film support, and a first emulsion layer unit and a second emulsion layer unit coated on the opposite surface of the support, respectively, each of the emulsion layer units having a bromide content of 50 based on silver. Silver halide grains having a molar ratio of more than mol% and an iodide content of less than 4 mol% and tabular grains having {111} major faces accounting for more than 50% of the total grain projected area;
A radiograph comprising at least one radiation-sensitive emulsion containing a spectral sensitizing dye adsorbed on the surface of the silver halide grain and a hydrophilic colloid vehicle which acts as a binder and a peptizer for the silver halide grain. A radiographic element, characterized in that at least the portion of the vehicle that acts as a peptizer is a hydrophilic colloid derived from a water dispersible cationic starch.

(2) The radiographic element according to (1), further characterized in that the cationic starch comprises α-amylose. (3) The radiographic element according to (1), further characterized in that the cationic starch comprises amylopectin. (4) The starch according to any one of (1) to (3), further characterized in that the starch contains a protonated amine component and a cation component selected from quaternary ammonium, sulfonium and phosphonium components. Radiographic elements.

(5) The cationic starch has 1st and 4th positions.
The radiographic element according to any one of (1) to (4), further characterized by containing an α-D-glucopyranose repeating unit having a bond at the position. (6) It is further characterized in that the cationic starch further contains a 6-position bond in a part of the α-D-glucopyranose repeating unit to form a branched polymer structure (5).
The radiographic element described in.

(7) The radiographic element according to any one of (1) to (6), further characterized in that the cationic starch is oxidized. (8) The oxidized cationic starch is further characterized in that it contains α-D-glucopyranose repeating units and, on average, at least one oxidized α-D-glucopyranose unit per starch molecule ( The radiographic element according to 7).

(9) The radiographic element according to (8), further characterized in that 3 to 50% of the α-D-glucopyranose units are ring-opened by oxidation. (10) It is further characterized in that the cationic starch is dispersed to at least a colloid level.
The radiographic element according to any one of (9).

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an assembly consisting of a dual-coated radiographic element mounted between two intensifying screens.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] September 24, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name]

[Correction method] Change

[Correction contents]

GEL 2% by weight gelatin solution (GEL) using bone gelatin
Was prepared. To this 4 liters, 27 mmol of NaBr was added and the pH was adjusted to 6.0 at 40 ° C. Water, CS
The viscosities of the solutions and GEL solutions were measured at various temperatures.
The results are shown below.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0119

[Correction method] Change

[Correction contents]

[0119] X = Unable to test because the solution solidified.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0124

[Correction method] Change

[Correction contents]

GEL-1 A 2% by weight gelatin solution (GEL-
1) was prepared. To this 4 liters, 27 mmol of NaBr was added and the pH was adjusted to 6.0 at 40 ° C. The viscosities of these three solutions were measured at various temperatures. The results are shown in Table IV.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0125

[Correction method] Change

[Correction contents]

[0125] X: The solution solidified.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03C 1/035 G03C 1/035 G 1/46 1/46

Claims (1)

[Claims] 1. A transparent film support, and a first emulsion layer unit and a second emulsion layer unit respectively coated on the opposite surface of the support, each of the emulsion layer units having a bromide content based on silver. Is more than 50 mol% and the iodide content is less than 4 mol%, {1
11} The tabular grains having major faces have a total grain projected area of 50
% Silver halide grains, a spectral sensitizing dye adsorbed on the surface of the silver halide grains, and a hydrophilic colloid vehicle that acts as a binder and a peptizer for the silver halide grains. A radiographic element comprising a type of radiation-sensitive emulsion, characterized in that at least the portion of the vehicle that acts as a peptizer is a hydrophilic colloid derived from a water-dispersible cationic starch. .