Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
1999-12-30
2001-07-24
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S567000
Reexamination Certificate
active
06265145
ABSTRACT:
FIELD OF THE INVENTION
This invention is directed to the preparation of radiation sensitive silver iodochloride emulsions useful in photography, including electronic printing methods wherein information is recorded in a pixel-by-pixel mode in a radiation sensitive silver halide emulsion layer. It particularly relates to the preparation of the exterior portions of emulsion grains after formation of a maximum iodide concentration sub-surface shell surrounding a central portion.
DEFINITION OF TERMS
The term “high chloride” in referring to silver halide grains and emulsions indicates that chloride is present in a concentration of greater than 50 mole percent, based on total silver.
In referring to grains and emulsions containing two or more halides, the halides are named in order of ascending concentrations.
The term “cubic grain” is employed to indicate a grain is that bounded by six {100} crystal faces. Typically the comers and edges of the grains show some rounding due to ripening, but no identifiable crystal faces other than the six {100} crystal faces. The six {100} crystal faces form three pairs of parallel {100} crystal faces that are equidistantly spaced.
The term “cubical grain” is employed to indicate grains that are at least in part bounded by {100} crystal faces satisfying the relative orientation and spacing of cubic grains. That is, three pairs of parallel {100} crystal faces are equidistantly spaced. Cubical grains include both cubic grains and grains that have one or more additional identifiable crystal faces. For example, tetradecahedral grains having six {100} and eight {111} crystal faces are a common form of cubical grains.
The term “central portion” in referring to cubical silver halide grains refers to that portion of the grain structure that is first precipitated accounting for up to 98 percent of total precipitated silver required to form the {100 } crystal faces of the grains.
The term “dopant” is employed to indicate any material within the rock salt face centered cubic crystal lattice structure of a silver halide grain other than silver ion or halide ion.
The term “dopant band” is employed to indicate the portion of the grain formed during the time that dopant was introduced to the grain during precipitation process.
The term “normalized” molar addition rate hereinafter assigned the symbol R
n
is a measure of the intensity of rate of addition of silver salt solution to the reaction vessel in case of a double-jet precipitation process. R
n
is defined by the formula:
R
n
=Q
f
C
f
/M
where Q
f
is the volumetric rate (liters/min) of addition of silver salt solution into the reaction vessel, C
f
is the molar concentration (moles/liter) of the said solution, and M is total moles of silver halide host grains in the reaction vessel at the precise moment of above addition.
All references to the periodic table of elements periods and groups in discussing elements are based on the Periodic Table of Elements as adopted by the American Chemical Society and published in the
Chemical and Engineering News,
Feb. 4, 1985, p. 26. The term “Group VIII” is used to generically describe elements in groups 8, 9 and 10.
The term “log E” is the logarithm of exposure in lux-seconds.
Photographic speed is reported in relative log units and therefore referred to as relative log speed. 1.0 relative log speed unit is equal to 0.01 log E.
The term “contrast” or “&ggr;” is employed to indicate the slope of a line drawn from stated density points on the characteristic curve.
The term “reciprocity law failure” refers to the variation in response of an emulsion to a fixed light exposure due to variation in the specific exposure time.
Research Disclosure
is published by Kenneth Mason Publications, Ltd., Dudley House, 12 North St., Emsworth, Hampshire P010 7DQ, England.
BACKGROUND
In its most commonly practiced form silver halide photography employs a film in a camera to produce, following photographic processing, a negative image on a transparent film support. A positive image for viewing is produced by exposing a photographic print element containing one or more silver halide emulsion layers coated on a reflective white support through the negative image in the camera film, followed by photographic processing. In a relatively recent variation negative image information is retrieved by scanning and stored in digital form. The digital image information is later used to expose imagewise the emulsion layer or layers of the photographic print element.
Whereas high bromide silver halide emulsions are the overwhelming commercial choice for camera films, high chloride cubic grain emulsions are the overwhelming commercial choice for photographic print elements. It is desired in high chloride emulsions for color paper applications to obtain high photographic speed at the desired curve shape. While it has been common practice to avoid or minimize the incorporation of iodide into high chloride grains employed in color paper, it has been recently observed that silver iodochloride cubical grains can offer exceptional levels of photographic speed where iodide is incorporated in such emulsion gains in a profiled manner. Chen et. al. in U.S. Pat. No. 5,547,827; Chen et. al. in U.S. Pat. No. 5,550,013; Chen et. al. in U.S. Pat. No. 5,605,789; Chen et. al. in U.S. Pat. No. 5,726,005; Edwards et.al. in U.S. Pat. No. 5,728,516; Chen et. al. in U.S. Pat. No. 5,736,310; Budz et.al. in U.S. Pat. No. 5,783,372 and Edwards et.al. in U.S. Pat. No. 5,792,601 disclose highly sensitive silver iodochloride cubical emulsions with low levels of iodide located in the exterior portions of the grains. The interior portions of such grains can be prepared by employing any convenient high chloride cubical grain precipitation procedure. The emulsion grains thus formed then serve as hosts for further growth. Once a host grain population has been prepared, an increased concentration of iodide is introduced into the emulsion to form the region of the grains containing maximum iodide concentration. The source of iodide ion can be silver iodide grains or any iodide-releasing agent, but it is typically disclosed that iodide is preferably introduced alone as an aqueous solution of an alkali metal iodide salt. This is followed by double-jet introduction of silver nitrate and alkali metal chloride solutions at conventional molar addition rates, constant or ramped, till the exterior portion is grown to the desired size.
Chow U.S. Pat. No. 5,549,879 discloses a pulsed flow double jet technique for preparing silver halide grains. Chow discloses introducing an aqueous silver nitrate solution from a remote source by a conduit which terminates close to an adjacent inlet zone of a mixing device, which is disclosed in greater detail in
Research Disclosure,
Vol. 382, February 1996, Item 38213. Simultaneously with the introduction of the aqueous silver nitrate solution and in an opposing direction, aqueous halide solution is introduced from a remote source by a conduit which terminates close to an adjacent inlet zone of the mixing device. The mixing device is vertically disposed in a reaction vessel and attached to the end of a shaft, driven at high speed by any suitable means. The lower end of the rotating mixing device is spaced up from the bottom of the vessel, but beneath the surface of the aqueous silver halide emulsion contained within the vessel. Baffles, sufficient in number to inhibit horizontal rotation of the contents of the vessel are located around the mixing device.
Chow teaches operating the described apparatus in a “pulse flow” manner comprising the steps of: (a) providing an aqueous solution containing silver halide particles having a first grain size; (b) continuously mixing the aqueous solution containing silver halide particles; (c) simultaneously introducing a soluble silver salt solution and a soluble halide salt solution into a reaction vessel of high velocity turbulent flow confined within the aqueous solution for a ti
Budz Jerzy A.
Hendricks, III Jess B.
Jagannathan Ramesh
Jagannathan Seshadri
Mehta Rajesh V.
Anderson Andrew J.
Baxter Janet
Eastman Kodak Company
Walke Amanda C.
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