Silver halide photographic material

Details Silver halide photographic material Silver halide photographic material

2000-01-06

2002-12-31

Baxter, Janet (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Radiation sensitive product

Silver compound sensitizer containing

C430S569000, C430S586000, C430S599000

Reexamination Certificate

active

06500607

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a silver halide (hereinafter referred to as “AgX”) photographic material which is useful in the field of photography, and particularly relates to a photographic material improved in sensitivity and image quality.
BACKGROUND OF THE INVENTION
It has been required to further improve sensitivity and image quality of photographic materials. When tabular AgX grains are used in photographic materials, the main planes of tabular grains are oriented in parallel to the support, leading to the thinning of the AgX emulsion layer. The improvement of sharpness and speed-up of development have been contrived by making use of this property. There is a maleficent effect of image quality deterioration due to light reflection by interrelation between a tabular grain and an incident light. However, further improvement of sensitivity and image quality has been required by dissolving this problem.
Coherence of the thickness of a tabular grain and a monochromatic light is described in
Research Disclosure
, No. 25330, May (1985), but there is no description with respect to the specific way of improvement by making use of that characteristic.
There are disclosed in JP-A-6-43605 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) the fact that the thickness of the tabular grain in the photosensitive layer farthermost from the exposure light source makes the light reflection in the photosensitive spectrum region of the emulsion the smallest, and the embodiment of also making the thicknesses of the tabular grain in other photosensitive layers optimal in the photosensitive wavelength region of the photosensitive layer to make the light reflection the smallest, but the improving effect of sensitivity and image quality is small only with these embodiments.
When reflection occurs by the incident light from a dispersion medium layer to an AgX layer, in general, the electric field vector of the incident wave and the electric field vector of the reflected wave are in opposite directions and they offset each other, as a result, the light strength on the vicinity of the interface weakens. There is hence the disutility that the light absorption amount of the sensitizing dye adsorbed onto the interface is inhibited, and the improvement of this disutility is also demanded.
The image quality variation of a red-sensitive layer by changing the location of the red-sensitive layer in a color photographic material comprising a blue-sensitive layer, a green-sensitive layer and a red-sensitive layer is described in
Journal of Imaging Science and Technology
, Vol. 38, pp. 32 to 35 (1994). If the location of a red-sensitive layer is changed, however, the image qualities of other photosensitive layers are deteriorated and the entire color balance also lowers, which produces a disadvantageous result.
Addition of TiO
2
particles having a primary particle diameter of from 1 to 100 nm to a photo-insensitive layer as a UV absorber is disclosed in JP-A-10-62904, U.S. Pat. Nos. 5,731,136 and 5,736,308. They propose to use TiO
2
particles which are not deteriorated with the lapse of time as a UV absorber in place of conventional organic UV absorbers which are deteriorated with aging, and to use TiO
2
particles in a layer nearer to the light source than the color image-forming layer. They also propose to use as the TiO
2
those described in Gunter Buxbaum,
Industrial Inorganic Pigments
, pp. 227 to 228, VCH Weinheim, Tokyo (1993). These particles certainly comprise small primary particles, but they are particles in which 90 mol % or more of the entire particles are occupied by particles comprising 30 or more primary particles which are three dimensionally agglomerated with one another and having three dimensional structure. They are inappropriate particles for the object of the present invention. Further, the foregoing patents do not aim to inhibit light scattering of AgX grains by increasing the refractive index of the binder in a photosensitive layer, so that this technique is different from the object of the present invention.
A technique of mixing a colloidal silica to an AgX emulsion layer to improve a pressure characteristic is disclosed in JP-A-4-241551 and JP-A-5-53237, and a technique of super-rapid low replenishing development process is disclosed in JP-A-9-269560. However, the refractive index of the foregoing colloidal silica to the light having a wavelength of 500 nm is lower than that of gelatin (1.546), therefore, this technique cannot make the refractive index of a dispersion medium layer high.
On the other hand, a silver halide photographic material containing TiO
2
fine particles in the emulsion layer is disclosed in EP-A-930532 but this technique is different from the technique of the present invention in the point that the above photographic material is not subjected to desilvering processing after development.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a silver halide photographic material which is further improved in sensitivity and image quality.
The above object of the present invention has been achieved by the following items (i.e., the following embodiments and preferred embodiments of the present invention).
(I) Embodiments of the Present Invention
(1) A silver halide photographic material comprising a support having provided thereon at least one silver halide emulsion layer, wherein the silver halide emulsion layer contains, in the dispersion medium phase of the emulsion, one or more kinds (preferably from 1 to 20 kinds, and more preferably from 2 to 10 kinds) of inorganic fine particles having a refractive index of from 1.62 to 3.30(preferably from 1.70 to 3.30, and more preferably from 1.80 to 3.10) to the light having a wavelength of 500 nm, the total weight of the fine particles contained in the unit volume of the dispersion medium phase is from 1.0 to 95 wt % (preferably from 5 to 90 wt %, and more preferably from 15 to 70 wt %), the dispersion medium phase containing the fine particles is substantially transparent to the photosensitive peak wavelength light of the emulsion layer, and the photographic material is exposed and processed in the development process comprising at least a developing step and a fixing step. The silver halide photographic material preferably has the refractive index of the dispersion medium phase to the light having a wavelength of 500 nm higher by 0.05 to 0.90(preferably from 0.12 to 0.90, and more preferably from 0.20 to 0.90) than the refractive index of the time when the dispersion medium phase does not contain the inorganic fine particles, the light reflection strength of the emulsion layer to the photosensitive peak wavelength light of the emulsion layer is reduced due to the presence of the fine particles to 0.0 to 95% (preferably from 0.0 to70%, and more preferably from 2.0 to 40%) of the light reflection strength of the time when the emulsion layer does not contain the inorganic fine particles, and the below-described Z
1
value of the entire photographic image finally obtained through all the steps of development process is from 0.0 to 0.70 (preferably from 0.0 to 0.20, more preferably from 0.0 to 0.0S, and most preferably from 0.0 to 0.010).
Z
1
=[(the molar rate of the silver halide remaining in the finally obtained entire photographic image)/(the molar rate of the silver halide remaining in the entire photographic image obtained after development alone)]
(2) The silver halide photographic material as described in the above item (1), wherein from 50 to 100% (preferably from 80 to 100%, and more preferably from 95 to 100%) of the total projected area of the silver halide grains in the at least one silver halide emulsion layer are tabular grains having an aspect ratio (diameter/thickness) of from 2.0 to 300 ( preferably from 4.0 to 300, and more preferably from 4.0 to 100), a thickness of from 0.01 to 0.50 &mgr;m (preferably from 0.01 to 0.30 &mgr;m), and a diameter of from 0.1 to 30 &mgr;m (preferably from 0.1 to 10

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