GB2280276A

GB2280276A - Photographic colour element

Info

Publication number: GB2280276A
Application number: GB9315372A
Authority: GB
Inventors: David Neil Rogers
Original assignee: Kodak Ltd
Current assignee: Kodak Ltd
Priority date: 1993-07-24
Filing date: 1993-07-24
Publication date: 1995-01-25
Anticipated expiration: 2013-07-24
Also published as: GB9315372D0; GB2280276B

Abstract

A photographic photosensitive multicolour negative film element comprising a film support coated with an antihalation layer upon which is coated red-, green- and blue-sensitive emulsion layers and which film further contains at least one developer inhibitor-releasing compound wherein the red-sensitive emulsion layer contains less than 2.5 g/m<2> silver, the total silver coating weight is less than 8 g/m<2> (as silver) and wherein the antihalation layer contains a material that will trap developer inhibitor fragments e.g. a hydroquinones, Lippmann emulsions or Carey Lea silver.

Description

PHOTOGRAPHIC COLOUR ELEMENT This invention relates to photographic colour elements and, in particular, to colour elements having improved granularity.

There is a constant need, especially in the field of colour negative films, to improve performance.

Colour negative films typically comprise a support bearing (starting from the outermost layer) a yellow dye image-forming unit comprised of at least one bluesensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler, a blue light-absorbing layer, at least one magenta dye imageforming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, at least one cyan dye image-forming unit comprising at least one redsensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler and an antihalation layer.

One way of improving sharpness is to reduce the amount of silver in the red-sensitive image-forming unit.

This will reduce the thickness of the red-sensitive emulsion layers. However, it is not possible to do this without paying a penalty in some other sensitometric property, in particular, it leads to an increased gamma normalised granularity position.

The present invention provides a colour negative film having improved sharpness due to a lower silver laydown in the red-sensitive emulsion layer unit but without any loss in gamma normalised granularity.

According to the present invention there is provided a photographic photosensitive multicolour negative film element comprising a film support coated with an antihalation layer upon which is coated red-, green- and blue-sensitive emulsion layer units and which film further contains at least one developer inhibitorreleasing compound wherein the red-sensitive emulsion layer unit contains less than 2.5 g/m2 silver, the total silver coating weight is less than 8 g/m2 (as silver) and wherein the antihalation layer contains a material that will trap developer inhibitor fragments.

The advantage of the present invention is that lower silver laydown levels can be achieved without any change in the gamma normalised granularity position.

The red-sensitive emulsion layer unit preferably contains up to 2 g/m2 silver, particularly from 0.5 to 2 g/m2 silver.

The preferred total silver coating weight is from 3 to 7 g/m2 and particularly from 6 to 6.5 g/m2.

The antihalation layer traditionally comprises grey metallic silver but it may also comprise a dye or mixture of dyes. The material that will trap developer inhibitor fragments may, for example, be Carey Lea silver (yellow colloidal silver), oxidised developer scavengers, for example hydroquinones or Lippmann emulsions (very fine grain silver halide emulsions). The amount of such developer inhibitor fragment-trapping material may be from 10 to 750 preferably from 20 to 500 and especially from 50 to 300 mg/m2.

It is believed that only a small fraction of the total concentration of inhibitor fragments are trapped by the method of the present invention. The remaining fragments can therefore still diffuse into the upper layers and fulfil the necessary interimage requirements.

In the accompanying drawings Fig 1 and Fig 2 represent the results of Example 1 being plots of red gamma normalised granularity and red MTF respectively.

Typically, the present emulsion layer units of the present multicolour materials also contain dye imageforming couplers associated with the silver halide emulsions. As used herein, the term "associated with" signifies that the coupler is incorporated in the silver halide emulsion layer or in a layer adjacent thereto where, during processing, it is capable of reacting with silver halide development products.

Multicolour elements contain dye image-forming units sensitive to each of the three primary regions of the spectrum. Each unit can be comprised of a single emulsion layer or of multiple emulsion layers sensitive to a given region of the spectrum. The layers of the element, including the layers of the image-forming units, can be arranged in various orders as known in the art.

A typical multicolour photographic element comprises a support bearing yellow, magenta and cyan dye imageforming units comprising at least one blue-, green- or red-sensitive silver halide emulsion layer having associated therewith at least one yellow, magenta or cyan dye-forming coupler respectively. The element can contain additional layers, such as filter and barrier layers.

In the following discussion of suitable materials for use in the elements of this invention, reference will be made to Research Disclosure Item 308119, December 1989 published by Kenneth Mason Publications, Emsworth, Hants, United Kingdom. This publication will be identified hereafter as "Research Disclosure".

The silver halide emulsion employed in the elements of this invention can be either negativeworking or positive-working. Suitable emulsions and their preparation are described in Research Disclosure Sections I and II and the publications cited therein.

Suitable vehicles for the emulsion layers and other layers of elements of this invention are described in Research Disclosure Section IX and the publications cited therein.

The elements of the invention can include additional couplers as described in Research Disclosure Section VII, paragraphs F G and H and the publications cited therein.

The couplers of this invention and any additional couplers can be incorporated in the elements and emulsions as described in Research Disclosures of Section VII, paragraph C and the publications cited therein.

The photographic elements of this invention or individual layers thereof, can contain brighteners (see Research Disclosure Section V), antifoggants and stabilisers (see Research Disclosure Section VI), antistain agents and image dye stabiliser (see Research Disclosure Section VII, paragraphs I and J), light absorbing and scattering materials (see Research Disclosure Section VIII), hardeners (see Research Disclosure Section X), plasticisers and lubricants (see Research Disclosure Section XII), antistatic agents (see Research Disclosure Section XIII), matting agents (see Research Disclosure Section XVI) and development modifiers (see Research Disclosure Section XXI).

The photographic elements can be coated on a variety of supports as described in Research Disclosure Section XVII and the references described therein.

Photographic elements can be exposed to actinic radiation, typically in the visible region of the spectrum, to form a latent image as described in Research Disclosure Section XVIII and then processed to form a visible dye image as described in Research Disclosure Section XIX. Processing to form a visible dye image includes the step of contacting the element with a colour developing agent to reduce developable silver halide and oxidise the colour developing agent. Oxidised colour developing agent in turn reacts with the coupler to yield a dye.

Preferred colour developing agents are pphenylene diamines. Especially preferred are 4-amino-3methyl-N,N-diethylaniline hydrochloride, 4-amino-3 methyl-N-ethyl-N-b-(methanesulphonamido) ethylaniline sulphate hydrate, 4-amino-3-methyl-N- ethyl-N-bhydroxyethylaniline sulphate, 4-amino-3-b (methanesulphonamido) ethyl-N, N-diethylaniline hydrochloride and 4-amino-N-ethyl-N-(2-methoxy- ethyl)m-toluidine di-p-toluene sulphonate.

With negative-working silver halide emulsions this processing step leads to a negative image. To obtain a positive (or reversal) image, this step can be preceded by development with a non-chromogenic developing agent to develop exposed silver halide, but not form dye, and then uniform fogging of the element to render unexposed silver halide developable. Alternatively, a direct positive emulsion can be employed to obtain a positive image.

Development is followed by the conventional steps of bleaching, fixing, or bleach-fixing, to remove silver and silver halide, washing and drying.

The following Example is included for a better understanding of the invention.

EXAMPLE 1 A photographic material of the following structure was prepared. The figures represent laydown in g/m2, emulsion laydowns being the amount of silver coated.

Overcoat layer Gelatin 1.20 Matt Beads 0.01 Blue-sensitive emulsion layer unit Gelatin 1.9 Blend of three blue-sensitised emulsions (Ag) 0.84 Coupler 1 1.00 Coupler 2 0.09 Bis vinylsulphonylmethyl ether (hardener) 0.25 Yellow filter layer Gelatin 1.0 Yellow Lippmann emulsion 0.06 Green sensitised emulsion layer unit Gelatin 3.0 Blend of three green-sensitised emulsions (Ag) 1.50 Coupler 3 0.95 Coupler 4 0.33 Interlayer Gelatin 1.00 Red sensitised emulsion layer unit Gelatin 3.10 Blend of three red-sensitised emulsions 2.00 (Ag) Coupler 5 0.10 Coupler 6 0.02 Coupler 7 1.00 Antihalation layer Gelatin 2.4 Yellow Lippmann emulsion (Ag) 0.30 ////// SUPPORT ////// The couplers used are as follows: Coupler 1

Coupler 2

Coupler 3

Coupler 4

Coupler 5

Coupler 6

Coupler 7

A control photographic material was also coated which contained 0.3 g/m2 grey silver instead of the Lippman emulsion in the antihalation layer.

The material was exposed to a test step wedge and processed by the following process at 38 "C: 1. Colour developer 3.25 mins 2. Bleach 4.33 mins 3. Wash 1.08 mins 4. Fix 4.33 mins 5. Stabilise 1.08 mins Colour developer Sodium hexametaphosphate 2.0 g Sodium sulphite (anhy) 4.25 g Potassium bromide 1.5 g Hydroxylamine sulphate 2.0 g 4-(N-ethyl-N-2-hydroxyethyl)-2methylphenylenediamine 4.75 g Water to 1.0 litre pH = 10.1 Bleach Sodium iron(III) ethylenediaminetetra-acetic acid 100.0 g Ammonium bromide 150.0 g Acetic acid 6.0 ml Water to 1.0 litre Fixer Ammonium thiosulphate 120.0 g Sodium sulphite (anhy) 20.0 g Potassium metabisulphite 20.0 g Water to 1.0 litre Stabiliser Formaldehyde (36% soln) 6.0 ml Water to 1.0 litre.

The results are shown in figs 1 and 2 of the accompanying drawings. The sharpness and granularity figures are for a 35mm film system.

Fig 1 shows D/logE and red gamma normalised granularity curves (white light exposure) relative to the control coating while Fig 2 shows the red MTF curve (white light exposure) relative to the control coating. The loss of 2.4 AMT (acutance) is compensated for by the gain of 4 grain units. This loss in sharpness is significant but less than the gain in sharpness caused by silver laydown reduction in the upper layers.

Claims

CLAIMS:

1. A photographic photosensitive multicolour negative film element comprising a film support coated with an antihalation layer upon which is coated red-, green- and blue-sensitive emulsion layer units and which film further contains at least one developer inhibitorreleasing compound wherein the red-sensitive emulsion layer unit contains less than 2.5 g/m2 silver, the total silver coating weight is less than 8 g/m2 (as silver) and wherein the antihalation layer contains a material that will trap developer inhibitor fragments.

2. A photographic negative film as claimed in claim 1 in which the red-sensitive emulsion layer unit contains up to 2 g silver/m2

3. A photographic negative film as claimed in claim 1 or 2 in which the total silver coating weight is from 3 to 7 g/m2 (as silver).

4 A photographic negative film as claimed in any of claims 1-3 in which the material that will trap developer inhibitor fragments is a hydroquinone or a Lippmann emulsion.

5. A photographic negative film as claimed in any of claims 1-4 in which the material that will trap developer inhibitor fragments is present in am amount of from 10 to 750 mg/m2.

6. A photographic negative film as claimed in any of claims 1-5 in which the material that will trap developer inhibitor fragments is present in am amount of from 20 to 500 mg/m2.

7. A photographic negative film as claimed in any of claims 1-6 in which the material that will trap developer inhibitor fragments is present in am amount of from 50 to 300 mg/m2.