WO1991019224A2

WO1991019224A2 - Color photographic materials containing polymers which improve photographic performance

Info

Publication number: WO1991019224A2
Application number: PCT/US1991/003765
Authority: WO
Inventors: Edward Schofield; Tien-Teh Chen
Original assignee: Eastman Kodak Company
Priority date: 1990-06-01
Filing date: 1991-05-30
Publication date: 1991-12-12
Also published as: EP0540533A1; WO1991019224A3; JPH05503173A

Abstract

Incorporation in a spectrally sensitized silver halide photographic element of a copolymer comprising repeating units of a methoxy- or ethoxy-containing acrylate or acrylamide and a different methoxy or ethoxy containing acrylate provides improvements with respect to one or more of sensitizing dye stain, retained silver and minimum density.

Description

COLOR PHOTOGRAPHIC MATERIALS CONTAINING POLYMERS WHICH IMPROVE PHOTOGRAPHIC PERFORMANCE

This is a continuation-in-part of U.S. Patent Application Serial No. 531,827 filed June 1, 1990.

Field of the Invention

This invention relates to color photographic materials and in particular to such materials which contain acrylate copolymers.

Background of the Invention

Color photographic elements contain a silver halide emulsion dispersed in a binder, such as gelatin, and a dye former. A usual dye former is a dye-forming coupler which typically is dispersed in a high boiling organic solvent, know as a coupler solvent. In almost all color photographic elements, silver halide grains have adsorbed thereto a spectral sensitizing dye which renders the grain sensitive to a desired region of the electromagnetic spectrum.

Over the years, the association of synthetic polymers with the various layers of color photographic elements has been suggested for a variety of purposes. Commonly such polymers have been suggested as partial or complete replacements for the gelatin binder in which the silver halide grains, are dispersed. In addition, polymers have been suggested as a means for incorporating the dye-forming coupler in the emulsion layer. In this connection, see Chen U.S. Patent

4,214,047, issued July 22, 1980. Also, various

polymers and polymer lattices have been suggested to provide other beneficial properties or performance features for photographic materials. An example of the latter is Lau et al. U.S. Patent 4,914,005 issued

April 3, 1990, which describes the use of polymers latexes containing repeating units derived from methoxyalkylyacrylates to reduce the loss of cyan image dye in materials processed in bleach solutions

containing ferric ion complexes. There exists the need for further improvements in the performance of photographic materials, in

particular with respect to one or more of the following: a) reducing the amount of sensitizing dye

remaining in the element after processing, hence reducing the amount of stain due to retained sensitizing dye; b) increasing the bleachability of silver ion; hence reducing the amount of silver

retained in the photographic element after processing; and c) reducing the increase in minimum dens ity upon keeping of the unprocessed photographic material.

Summary of the Invention

We have found that one or more of these improvements can be obtained by incorporating in a spectrally sensitized silver halide color photographic element a copolymer comprising a) repeating units derived from a methoxy- or ethoxy- containing acrylate or acrylamide monomer copolymerized with b) a different methoxy- or ethoxy-containing acrylate monomer

represented by the structure:

wherein

Z is the residue of one or more vinyl monomers, G is -O- or -NH-,

R¹ is -H or -CH ₃,

R² is -H or -CH₃, no more than one R² being -CH₃,

R³ and R⁴ are -CH₃ or -C₂H₅,

x is 15 to 90 weight percent,

y is 0 to 90 weight percent,

z is 0 to 85 weight percent, and

n is 1 to 20,

but if y=0, z must be ≥ 10.

Detailed Description of the Invention

In a preferred embodiment of this invention the repeating units represented by Z are derived from one or more acid- or salt- containing vinyl monomers.

In a particularly preferred embodiment of this

invention, one of R ³ and R⁴ is methyl and the other is ethyl group. Examples of monomers useful in preparing polymers of this invention are: methoxyethylacrylate or methacrylate, ethoxyethylacrylate or methacrylate, methoxyethoxyethylacrylate or methacrylate,

methoxyethylacrylamide or methacrylamide,

ethoxyethylacrylamide or methacrylamide, butyl

acrylate, acrylic acid, methacrylic acid,

hydroxyethylmethacrylate, hydroxyethylmethacrylamide, 2-methyl-2-[(1)-oxo-2-propenyl)amino]-1-propane

sulfonic acid, or its alkali metal salt,

polypropyleneglycol monomethacrylate,

polypropyleneglycol monomethacrylamide. The

polypropyleneglycol monomers contain from 1 to 20 glycol units.

The copolymers of this invention are free of repeating units containing dye-forming coupler moieties.

Copolymers containing methoxyethylacrylate, methoxyethylacrylamide or methacrylamide, are

especially preferred, especially when the property for which an improvement is sought is ferrous ion stability,

Highly preferred polymers useful in this invention can be represented by the structure:

wherein G, R¹ , R² and R⁴ are as defined above,

x is 35 to 85 weight percent,

y is 10 to 60 weight percent,

z¹ is 3 to 10 weight percent,

z² is 2 to 5 weight percent, and

n i s 1 to 20. The polymers useful in this invention can be prepared by known polymerization processes, such as emulsion and solution polymerization, using known starting materials. Polymers prepared by emulsion polymerization process can be mixed with gelatin and coated directly. Polymers prepared by solution

polymerization can be dispersed in two different ways. The first way is to disperse the polymer in the same way that a ballasted coupler is dispersed, with or without a coupler solvent. The thus formed dispersion is mixed with gelatin and coated. The second way is to disperse the polymer directly into water if enough units derived from ionizable monomers are present. The dispersion obtained is then mixed with gelatin and coated. A typical emulsion polymerization procedure is illustrated in the preparative example, infra.

The polymer preferably is incorporated in the element in the same layer as the silver halide

emulsion. It can be present in an amount that will vary depending upon the particular effect desired. Typically, the polymer can be present in an amount of 50 to 1000 mg per square meter or about 5 x 10³ to 4 x 10⁵ mg per weight silver. A preferred amount is between about 150 and 500 mg per square meter or about 5 x 10³ to 5 x 10⁴ mg per weight silver.

The polymers of this invention can be used with any of the silver halide emulsions employed in color photography. The silver halide can be silver bromide, silver bromoiodide, silver chloride, silver chlorobromide, or another silver halide typically used in photography. The silver halide grains can be of varying habit such as cubic, spherical or tabular.

Since tabular grains can adsorb greater amounts of sensitizing dye than grains of other habits, the present invention is particularly effective with such grains. The grains can be fine-grain or coarse-grain or of an intermediate size. The emulsions can be monodisperse, polydisperse or a combination of

monodisperse emulsions of different sizes.

The grains are spectrally sensitized with a cyanine or merocyanine dye. Typical spectral

sens itizing dyes are described in Research Disclosure, December 1989, Item No. 308119, Section IV. The present invention is particularly effective with the anionic sensitizing dyes described in the patents and applications referred to in that section.

Most commonly the silver halide emulsion contains a gelatin vehicle, although modified gelatins and other vehicles can be employed as described in

Research Disclosure. December 1989, Item No. 308119, Section IX.

The light sensitive layer in which the polymer of the present invention is contained preferably contains a dye-forming coupler compound. Couplers which form yellow dyes typically are arylacetanilides such as pivalyl acetanilides and benzolylacetanilides. Couplers which form magenta dyes typical are

pyrazolones and pyrazoloazoles such a

pyrazolotriazoles. Couplers which form cyan dyes typically are phenols and napthols. The present invention is particularly effective with cyan dye forming couplers and is especially preferred with phenolic couplers which contain substituents in the 2- and 5-positions. Suitable couplers of this type are described in U.S. Patents 3,476,563 and 4,004,929.

Photographic elements of the invention can be single color elements or multicolor elements.

Multicolor elements contain dye image-forming units sensitive to each of the three primary regions of the visible 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. In an alternative format , the emuls ions sens itive to each of the three primary regions of the spectrum can be disposed as a single segmented layer, e.g., as by the use of microvessels as described in Whitmore U. S . Patent 4 , 362 , 806 issued December 7 , 1982 .

In the following discussion of suitable materials for use in the emulsions and elements of this invention, reference will be made to Research

Disclosure, December 1989, Item 308119, published by Kenneth Mason Publications Ltd., Emsworth, Hampshire P01070Q England. This publication will be identified hereafter by the term "Research Disclosure". These couplers can be incorporated in the elements and emulsions as described in Research

Disclosure..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 stabilizers (See Research Disclosure Section VI), antistain agents and image dye stabilizers (See

Research Disclosure Section VII, paragraphs I and J), light absorbing and scattering materials (See Research Disclosure Section VIII), hardeners (see Research

Disclosure Section XI), plasticizers 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 color developing agent to reduce developable silver halide and oxidize the color developing agent. Oxidized color developing agent in turn reacts with the coupler to yield a dye. Preferred color developing agents useful in the invention are p-phenylene diamines. Especially preferred are 4-amino-N,N-diethyl-aniline

hydrochloride, 4-amino-3-methyl-N,N-diethylaniline hydrochloride, 4-amino-3-methyl-N-ethyl-N- β-(methanesulfonamido)-ethylaniline sulfate hydrate, 4-amino-3-methyl-N-ethyl-N-β-hydroxyethylaniline sulfate, 4-amino-3-β-(methanesulfonamido)ethyl- N,N-diethylaniline hydrochloride and 4-amino-N-ethyl-N- (2-methoxyethyl)-m-toluidine di-p-toluenesulfonic acid.

With negative working silver halide, the processing step described above gives 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 uniformly fogging 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 steps of bleaching, fixing, or bleach-fixing, as described above, washing and drying.

The polymers employed in this invention can be prepared by procedures known in the art and illustrated below. Typically this will be a free radical

polymerization leading to an aqueous latex polymer.

The resulting polymer typically is a high polymer having a molecular weight above about 1 x 10⁴.

In the examples which follow, polymers which illustrate the invention are as identified in Table 1, part A, which follows and comparison polymers are identified in Table 1, part B. In these tables the following abbreviation are uεed for the monomers employed: BA = Butyl acrylate

AA = Acrylic acid

MAA = methacrylic acid

NaAMP = 2-methyl-2-[(1)-oxo-2-propenyl)amino]- 1-propane sulfonic acid sodium salt

Preparative Example 1

Preparation of polymer 1-3 Co-poly(methoxyethylacrylate) (ethoxyethylacrylate) (acrylic acid)

(2-methyl-2—[(1—oxyl, 2-propenyl) amino] l-propane sulfonic acid sodium salt)

The following groups of ingredients were assembled:

group Ingredient Amount (grams) A Deionized water 260

Ammonium salts of sulfated 16.9 alkylphenoxypoly(ethyleneoxy)

ethanol-307. solid in water-4

sold by GAF Corp. as Alipal Ep-110 2-methyl-2[(l-oxyl-2- 1.2 propenol)]-l-propane sulfonic

acid sodium salt (507. solid in water)

B Ethoxyethylacrylate (M-2) 4.32

Methoxyethylacrylate (M-l) 11.71 Acrylic acid 0.87

C Ammonium

Persulfate(5T_) 8.45

E Ammonium

persulfate(5%) 8.45

Alipal EP-110 8.44

2-Methyl-2-[(1-oxyl-2- propenol)amino]-1-propane

sulfonic acid sodium salt 10.89

deionized water 8.0

F Ammonium

persulfate(5%) 8.45 The polymer was prepared as follows:

1) Group A was added to a 1 liter 4-neck, round-bottom flask equipped with a nitrogen inlet, thermometer, condensor, and a mechanical stirrer. The system was evacuated using an aspirator and filled with nitrogen. Evacuation and filling with nitrogen was repeated three times. The flask was heated to 80°C in a water bath and a nitrogen purge waε maintained during the course of the reaction.

2) The ingredients of Group B were added to the flask and stirred for several minutes. Group C was then added to initiate nucleation. After waiting about 10 minutes until the exothermic reaction had stopped, Groups D and E were added simultaneously to the flask over a period of 4 hours.

After all the monomers have been added,

Group F was added and the temperature was raised to 85°C and maintained there for 1 hour until all of the comonomers had reacted. The mixture was cooled to room temperature, and filtered. The latex polymer was purified by a DC-2 diafiltration unit to remove surfactants and electrolytes. Example 1 Reduction of Sensitizing Dye Stain

Photographic elements were prepared having the

following schematic structure:

_____________________________________________________________________

Overcoat layer:

Gelatin-5.4 g/m²

Bisvmylsulfonylmethylether hardener-95 mg/m ²

______________________________________________________________________

Light-sensitive layer:

gelatin-0.2 g/m²

0.9μ silver bromoiodide (3 weight % I, 0.9μ

equivalent circular diameter, 7.5:1 aspect

ratio)-1.6 g/m²

The silver bromoiodide grains are spectrally sensitized with 300 mg per weight silver of dye A (see below) and 515 mg per weight silver of dye B (see below). Cyan dye-forming coupler C (see below) 0.89 g/m² and Cyan dye forming coupler D (see below) 74 mg/m²

Polymer 1-3, see Table II below for amounts

___________________________________________________________________________

Support - Cellulose acetate

___________________________________________________________________________

The photographic elements were exposed through a neutral density step wedge and then processed using the C-41 process as described in the British Journal of Photography, 1982 Annual, pages 209-211. The amount of residual sensitizing dye A and B was determined by high pressure liquid chromotography.

It is observed from this data that the presence of Polymer 1-3 significantly reduces the amount of

sensitizing dye remaining in the photographic element upon processing. Example 2 Reduction of Sens itizing Dye Stain

Photographic elements were prepared having the

following schematic structure :

__________________________________________________________________

Overcoat layer:

Gelatin-5.4 g/m²

Bisvinylsulfonylmethylether hardener-95 mg/m²

__________________________________________________________________

Light-sensitive layer:

gelatin-0.2 g/m²

0.9μ silver bromoiodide (3 weight % I, 0.9μ

equivalent circular diameter, 7.5:1 aspect

ratio)-1.6 g/m²

The silver bromoiodide grains are spectrally sensitized with 300 mg per weight silver of dye A and 515 mg per weight silver of dye B. Cyan dye-forming coupler C 0.89 g/m² and Polymer 320 mg/m². See Table I above and Table III below for polymer identification.

_______________________________________________________________________

Support - Cellulose acetate

______________________________________________________________________

From the above, it will be seen that polymers of this invention greatly reduce the sensitizing dye stain.

Example 3 Reduction of Sensitizing Dye Stain

A series of photographic elements were prepared having the following structure:

________________________________________________________________________

Overcoat:

Gelatin-1.1 g/m²

Hardener-19 mg/m²

________________________________________________________________________

Light Sensitive Layer

Gelatin-1.5 g/m²

Silver Halide-see below Coupler-see below

Polymer I-3-(see Table IV below for amounts)

_________________________________________________________________________

Support:

Polyethylene coated paper with a gelatin overcoat.__________________________________________________________________________

Element A contained a silver chlorobromide emulsion in an amount of 0.33 g/m² silver, spectrally sensitized with 122 mg per weight silver of spectral sensitizing dye E. This element also contains 0.62 g/m² of coupler F. Element B contained a silver chlorobromide emulsion in an amount of .32 g/m² silver spectrally sensitized with 240 mg per weight silver of sensitizing dye G.

This element contained coupler H.

Element C contained a silver chlorobromide emulsion in an amount of .42 g/m² spectrally sensitized with 349 mg per weight silver of sensitizing dye I. This element contained 1.13 g/m² of yellow dye-forming coupler J. Sens. Dye E

ε

₃

These three elements were exposed to a neutral density step wedge and then processed in the EP-2 process described in The British Journal of Photography, supra. The amount of residual sensitizing dye in each of the elements was determined as in Example 1.

It is observed that presence of the polymer reduces the amount of sensitizing dye retained.

Example 4 Reduction in Keeping the Fog

A photographic element was prepared like element C described above in Example 3, except that the emulsion was a silver chloride emulsion containing .28 g/m² silver. The element was held at 49°C and 50%

relative humidity for 2 weeks. The element was then exposed and processed in the EP2 procesε described in

The British Journal of Photography, supra. The density

(D_min) in background areas, which receive no

exposure, was measured. The results are shown in

Table V below.

The above data indicates that polymers of the present invention effect a substantial reduction in fog

attributable to keeping.

Example 5 Silver Retention:

The presence of methoxyethylacrylate in the polymer has been shown in published European Patent Application

0 294 104, published December 7, 1988 to be beneficial for minimizing problems associated with leuco cyan dye formation. We have found that the presence of this monomer can aggravate retention of silver in the

element by interfering with the bleaching process. The presence of ethoxyethylacrylate in the polymer has less of an impact on retention of silver in the element. Thus, copolymers containing both methoxyethylacrylate and ethoxyethylacrylate minimize problems associated with leuco cyan dye and minimize silver dye retention. An element was prepared having the structure and

components shown in Example 2 except that the overcoat contained .2.15 g/m² of gelatin, the light-sensitive layer contained 2.2 g/m² of gelatin, the silver halide emulsion was present in an amount of 1.6 g silver/m² , the couplers employed were couplers C and D, and the polymer employed was from Table 1, as identified below in

Table VI. The elements were exposed and processed as in Example 1 above. The amount of silver retained was determined from the infra red density of the processed element.

The results are shown in Table VI.

This data shows that polymers containing

ethoxyethylacrylate have less of an impact on silver retention than do polymers containing

methoxyethylacrylate. Example 6 Ferrous Ion Stability

Photographic elements were prepared having the following schematic structure:

_______________________________________________________________________

Overcoat layer:

gelatin-5.4 g/m²

Bisvinylsulfonylmethylether hardener-95 mg/m²

_________________________________________________________________________ Light-sensitive layer:

gelatin-0.2 g/m²

0.9μ silver bromoiodide (3 weight % I, 0.9μ

equivalent circular diameter, 7.5:1 aspect

ratio)-1.6 g/m ²

The silver bromoiodide grains are spectrally sensitized with 300 mg per weight silver of sensitizing dye A and 515 mg per weight silver of sensitizing dye B. Cyan dye-forming coupler K (see below) 0.74 g/m²

Polymer 320 mg/m² (See Table I above and Table VII below for identification)

_________________________________________________________________________

Support - cellulose acetate

________________________________________________________________________

Coupler K

Ferrous ion stability is determined as follows

Coatings are exposed and processed as described in Example 1. Densitometry of processed strips is recorded.

Processed strips are immersed in Solution X (below) under a nitrogen atmosphere for 5 min., washed with water for 5 min., and the densitometry re-read.

The % density loss from D~1.0 is shown in Table VII.

Solution X: 256.8 g EDTA

220 ml cone NH₄OH

229.4 g FeSO₄

made up to 8000 ml with water

pH 5.0.

This data shows that polymers of this invention greatly improve the Fe(II) stability of cyan dye.

This invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims

What is claimed is :

1. A photographic element comprising: a spectrally sensitized silver halide emulsion, a dye forming coupler, and

a copolymer comprising a) repeating units derived from a methoxy- or ethoxy- containing acrylate, acrylamide or methacrylamide monomer copolymerized with b) a different methoxy- or ethoxy-containing acrylate monomer, represented by the structure:

wherein

Z is the residue of one or more vinyl monomers, G is -O- or -NH-,

R¹ is -H or -CH₃,

R² is -H or -CH₃, no more than one R² being -CH₃,

R³ and R⁴ are -CH₃ or -C₂H₅,

x is 15 to 90 weight percent,

y is 0 to 90 weight percent,

z is 0 to 85 weight percent, and

n is 1 to 20,

but if y=0, z must be ≥ 10.

2. A photographic element of claim 1, wherein Z comprises units derived from an acid- or salt- containing vinyl monomer.

3. A photographic element of claim 2, wherein Z is selected from units having the following

structures:

4. A photographic element of claim 1, wherein the copolymer comprises repeating units derived from a) methoxyethylacrylate

b) ethoxyethylacrylate

c) acrylic acid and

d) 2-methyl-2-((1)-oxo-2-propenyl)amino)- 1-propane sulfonic acid or its salt.

5. A photographic element of claim 1 wherein the copolymer comprises repeating units derived from a) methoxyethylacrylamide

b) ethoxyethylacrylate

c) acrylic or methacrylic acid.

6. A photographic element of claim 1 wherein the copolymer comprises repeating units derived from a) methoxyethylmethacrylamide

b) ethoxyethylacrylate

c) acrylic or methacrylic acid.

7. A photographic element of claim 1, wherein the copolymer is in the same layer as the silver halide emulsion.

8. A photographic element of claim 1, wherein the silver halide emulsion is spectrally sensitized with an amionic sensitizing dye.

9. A photographic element of claim 8, wherein the silver halide emulsion is sensitized to the red region of the visible spectrum.

10. A photographic element of claim 8, wherein the silver halide emulsion comprises tabular silver halide grains having an aspect ratio of 5:1 or greater.

11. A photographic element of claim 9, wherein the dye forming coupler is a cyan dye forming coupler.

12. A photographic element of claim 11, wherein the cyan dye forming coupler is a naphtholic cyan dye forming coupler.