CA1116004A - Photographic materials containing sulfonate copolymers - Google Patents

Abstract

Abstract of the Disclosure Disclosed herein are compositions useful for the preparation of flexible coatings, particularly to photographic materials, which have improved stability to organic solvents and dissolved salts. The compositions comprise an aqueous dispersion of a hydrophillic colloid and a copolymer having a glass transition temperature less than or equal to 60°C comprising: from about 50 to about 70 percent by weight of an ester of an ethylenically unsaturated carboxylic acid; from about 2 to about 18 percent by weight of an amide of an ethylenically unsaturated carboxylic acid; from about 10 to about 30 percent by weight of 2 vinyl benzene; and from about 2 to about 18 percent by weight of a sulfonate monomer having the formula

Description

This invention relates to the preparation and use Or latex copolymers o~ the acrylic type to ~rnprove the physical properties of photographic layers containing hydrophilic colloids.

Proteinaceous hydrophilic colloids are known to be userul in many connectio~s, particularly those of a photographlc nature, due to the optical clarity Or attenuated products ~hich may be prepared there~rom. Gelatin or gelatin derivatives, for example, are typical o~ the hydrophilic colloids which have been ~ound to be useful in this respect.
However, these colloids exhlbit physical properties which are objectionable in certain applications. Many o~ these objections have been met by mixing or "extending" the colloid with one or more synthetic materials such as synthetic polymers.
Exemplary of the art showing the use of polymers with colloids such as ~elatin to over~me various problems are U.S. Patent 3,411,911 (Dykstra), issued November 19, 1968; U.S. Patent 3,536,491 (Rees et al), issued October 27, 1970; U.S. Patent 3,628,957 (~ranco et al), issued December 21, 1971; U.S. Patent 3,700,456 ~Smlth), Is6ued October 24, 1972; U.S. Patent 3,745,007 ~ 6QU~

(Nagae et al), issued July 10~ 1973; U.S. Patent 3,~11,897 (Babbit et al), issued May 21, 1974; British Spectfication 1,147,139, published April 2, 1969; Britlsh Speciricatlon 1,178,177, published January 21, 1970, and British Specirication 1,351,767, published May 1, 1974.
In particular, U.S. Patents 2,739,137 (Fowler), issued March 20, 1956; 2,772,163 (Tong), issued November 27, 1956; and

2,852,386 (Tong), issued September 16, 1958 disclose thè
preparation Or hydrosols comprising aopolymers Or unsaturated aliphatic amides, acrylic acid esters and a styrene compound and their use in photographic emulsions to disperse color couplers - and to irr,prove the ~lexibility Or gelatin and like colloids.
British Patent 1,181,508, published February 18, 1970 and its addition, published February 18, 1970 relates to a gelatin extender which is a copolymer comprising two acrylic acid esters, one of which has an active methylene group in an alcohol moiety Or the este:- or a substituent and a sulioes~er monomer.
The copolymers can be crosslinked through the active methylene groups to provide stability to the gelatin binder. These polymers, however, have been shown to be susceptible to the formation Or microscopic and macroscopic agglomerates when treated with water-miscible solvents or water-soluble salts.

Sulroeste~ monomers have been copolymerized with other ethylenically unsaturated rnonomers for various purposes.
Particularly, acrylamidosulfonates have been homopolymerized and copolymerized with acrylonitriles for use as water-soluble rilms and as textile fipers, as disclosed in U.S. Pz~ents 2,983,712 ~W1lk1nson), issued May 9, 1961; 3,332,904 (~a Combe et al), issued July 25, 1967; and 3,506,707 (Miller et al), issued April 14~ 1970. ~.S. Patent 3,547,899 (Arlt et al), issued December 15, 1970 and British Specirication 1~197,323, published July 1, 1970 disclose the copolymerization Or acrylamidosulronates with a variety of monomers, inclucling alkyl esters and styrene to prepare copolymers userul as rilms and flbers showing a high degree o~ whiteness and an outstanding a~rinity ror basic dyes.
These ~e~erences teach no photographic uses for these polymers.
Many latex polymers ~hich are used as gelatin extenders, particularly those disclosed by U.S. Patents 2,739,137 (Fowler);
2,772,163 (Tong); and 2,852,386 (Tong), are susceptible to gelatin-latex agglomeration and coagulation caused by salts and organic '' solvents. This agglomeration in coating melts leads to limited melt stability, excessive rilter plugging and coatin~ derects commonly referred to as "double-ended comets". Further, due to this agglomeration, partially-used melts cannot be sent to storage for reuse at a later time. The result is considerable waste and less than opti~.um rlexibility in preparing melts and scheduling emulsion coating machines.
Hence, there is a continuing search for latex' polymers ~-hich can be used as gelatin extenders which are not susceptible to the problems disclosed hereinabove. These polymers must be stable to organic solvents and dissolved salts normally used in photographic emulsions.

In accordance ~Jith this invention, it has been round that particular sulfonate-containing latex copolylners are more stable in the presence Or organic solvents or dissolved salts when used ~th hydrophilic colloids to prepare flexible coatings than polymers previously used in the art for this purpose. In addition, the resulting polymers surprisingly impart a highly desirable increase in photographic speed and an improvement in contrast, as well as dye hue shi~ts in color photographic materials.
In one aspect of the present invention, a composition useful for the preparation of flexible coatings comprises an aqueous dispersion of a hydrophilic colloid and a copolymer having a glass transition temperature less than or equal to 60C com-prising ~rom about 50 to about 70 percent by weight of an esterof a polymerized ethylenically unsaturated carboxylic acid mono-mer; from about 2 to about 18 percent by weight of an amide of a polymerized ethylenically unsaturated carboxylic acid monomer;
from about 10 to about 30 percent by weight o~ a polymerized vinyl benzene; and from about 2 to about 18 percent by weight of a poly-merized sulfonate monomer having, prior to polymerization, the formula (I):

,~
CH2=C ( R ~ SO3X (I) such that the total amount of polymerized amide and sulfonate monomers is less than about 20 percent by weight of the total copolymer weight, wherein R is hydrogen or alkyl; Rl is selected from the group consisting of alkylene and -~-R2-; R2 is divalent amino substituted with alkyl or hydrogen, or ~H2~nO- wherein n is an integer from 0 to 5; m is either 0 or 1, and X is hydrogen or a monovalent cation.
In another aspect of the present invention, a photo-graphic element comprises a support having thereon at least one silver halide emulsion layer and at least one layer comprising an aqueous dispersion of a hydrophilic colloid and copolymer having a glass transition temperature less than or equal to 60C com-~' ., prising fxom about 50 to about 70 percent by weight of an ester of a polymerized ethylenically unsaturated carboxylic acid; rom about 2 to about 18 percent by weight of an amide of a polymerized ethylenically unsaturated carboxylic acid; from about 10 to about 30 percent by weight of a polymerized vinyl benzene; and from about 2 to about 18 percent by weight of a polymerized sulfonate monomer having, prior to polymerization, the ormula (I) described hereinabove, such that the total amount of polymerized amide and sulfonate monomers is less than about 20 percent by weight of the total polymer weight.
As described hereinabove, in one aspect of the pxesent invention, a composition useful for the preparation of flexible coatings comprises an aqueous dispersion of a hydrophilic colloid and a copolymer having a ~lass transition temperature less than or equal to 60C comprising from about 2 to about 18 percent by weight of a polymerized sulfonate monomer having, prior to poly-merization, the formula (I):
R
CH2=C~-~ R ~ S03X (I) wherein m is 0 or 1; R is hydrogen or alkyl, preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl and isomers thereof; Rl can be ~:
alkylene, preferably of from 1 to 10 carbon atoms, such as methyl-ene, ethylene, propylene, butylene, pentylene, hexylene, heptalene, octalene, nonylene, decylene and isomers thereof and can be sub~
stituted with a variety of substituents. Rl can also be -~-R2-wherein R2 is amino having the formula -N-R - wherein R is hydro- -gen or a branched or linear alkyl having from 1 to 10 carbon ;:
atoms, such as described above for R. R4 is a branched or linear 30 alkylene having from 1 to 10 carbon atoms, s~ch as described .
above for Rl. R can also be ~ . . . . .
.. . . .

r~f~

~CH2~nO- wh~rein n ls an integer from 0 to 5.
X is hydrogen or a monovalent cation, such as an alkali metal cation as exemplified by lithium, sodium, potassium, rubidium an~ the like; copper (I), and others known 'o those skilled in the art.
Exemplary o~ sulronate monomers useful in the preparation Or the copolymers described herein are sodium 2-acrylamido-2-methylpropane sulfonate~ sodium 2 acrylamido~2,Z-dimethylpropane sul~onate 3 sodium 2-methacrylamido-2-methyl~ropane sul~onate, sodium 2-methacrylamido-2,2 dimethylpropane sulfonate, 2-acrylamido-2-methylpropane sulronic acid, 2-acrylamido-2-ethylpropane sulronic acid, sodium 2-acrylamido-2-ethylpropane sulfollate, sodium vinyl sulfonate, potassium vinyl sulronate, "
sodium 2-propenyl sulfonate~ CH2=CH-C-CH20-S03Na, and the like.

As noted above, from about 50 to a~out 70 percent by weight of the copolymers use~ul in the present invention can comprise an ester of a polymerize~ ethylenically unsaturated carboxylic acid. As exemplary of such monomers may be listed: methyl acrylate, ethyl acrylate, propyl acrylateg n-butyl acrylate, and other alkyl acrylates, 2-hydroxyethyl acrylate, 2-hydroxy-propyl.acrylate and other hydroxyalkyl acrylates; methyl methacrylate~ ethyl methacrylate, propyl methacrylate, n-butyl methacrylate and other alkyl methacrylates; 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate and other hydroxyalkyl methacrylates; esters of (m- and p-vinylphenyl) acetic acid, m- and p-vinylbenzoic acid, 3-acrylamido-3-methylbutanoic acid and other ethylenically unsaturated carboxylic acids.
Preferred monomers include alkyl esters Or acrylic acid such as methyl acrylate, ethyl acrylate, propyl acrylate,

3 n-butyl acrylate and the llke.

In addition, rrom about 2 to about 18 percent by weight of the copolymers described herein can comprise an amide of an ethylenically unsaturated carboxylic acid.
Exemplary of such monomers are: acrylamide, methacryl-amide, N-isopropylacrylamide, N-(l,l-dimethyl-3-dimethyl-aminopropyl)acrylamide, N-t-butylacrylamide, diacetone-acrylamide and the like.
Further, as noted above, from about 10 to about 30 percent by weight of the copo:Lymers useful in the present invention can comprise a polymerized vinyl benzene.
Such monomers include styrene, vinyltoluene, ~-methyl~
styrene, p-bromostyrene, p~t-butylstyrene, styrene sulronic acid, sodium salt, and other substituted styrenes.
Examples of copolymers useful herein include a copolymer of n butyl acrylate (40-60 weight percent), methacrylamide (4-15 weight percent), styrene (10-30 weight percent) and sodium 2-acrylamido-2-methylpropane sulfonate (2-18 weight percent); poly(butyl acrylate-co-s~yrene-co-sodium vinyl sulfonate-co-methacrylamide) (58.8:25.2:8:8 weight ratio); and poly(methyl acrylate~
co-styrene co-sodium 2~acrylamido-2-methyl propane sul~onate-co-methacrylamide) (58.8:25.2:8:8 weight ;
ratio).
The sulfonate monomers use~ul in preparing the copolymers o~ the present invention can be obtained rrom commercial sources or prepared by the techniques disclosed in U.S. 2,983,712 (Wilkinson), issued May 9, 1961; 3,332,904 (La Combe et al), issued July 25, 1967;
and 3,506,707 (Miller et al), issued April 14, 1970.
The other monomers useful in preparing the copolymers described herein are either commercially available or prepared by methods known to those skilled in the art.

The glass transition temperatures (Tg), as used in this invention and set ~orth in this specifi-cation, unless -7a~

~ . ~

. ... ._ otherwise speciried, can be determined by di~rerentlal scannlng calorimetry as disclosed in "Techniques and Methods Or Polymer Evaluation",Vol. 2, Marcel Dek}cer~ Inc., N.Y. 1970. The glass transition temperatures Or the copolymers described herein are less than or equal to 60C, and preferably ~rom about 20C
to about +lO~C.
The molecular wei~hts Or the copolymers use~ul ir.
the present invention are subJect to wide variation, but are o~ten in the range of about 104 to about 106. These copolymers prererably have inherent viscosities (0.25 g polymer in 100 ml acetic acid at 25C) Or ~rom about 0.3 to about 0.9, and more -preferably ~rom about 0.4 to about o.6. As used herein, the term "inherent viscosity" is determined by the ~ormula ~ inh = 2.30 log ~ rel .. ..
C

wherein ~inh is th~ inherent viscosity~ ~ rel is the relative viscosity o~ acetic acid solution Or the polymer and C is the con-centration in grams (0~25) Or polymer per 100 cc o~ solution.

The latex copolymers useful in the present inventlon can be prepared by well ~nown polymerization techniques~ The preferred methods include variations Or emulsion polymerization such as batch~ semi-continuous and continuous polymerization methods. Preparation 1 shows one semi-continuous method of making the latex copolymer by premlxing the mono~,ers in a head tank with a suitable surrace active a~ent to make a rairly homo~eneous monomer mixture. This mi~ture is then added to an aqueous solution Or sur~ace active agent and catalyst in a reactor vessel. The time period ~or addition can be ~rcm 10 to 120 mlnutes, prererably 30 minutes, and is var~ed to produce dir.erent -B-physical properties in the interpolymer, such as molecular weight.
The temperature at which the polyrners described herein are prepared is subJect to wide variation since this temperature depends upon such variable reatures as the specific monomers used, duration of heating, pressure employed and llke considerations.
However, the polymerization temperature generally does not exceed about 110C, and most often it is in the range Or about 50 to about 100C. The ~ressure employed in the polymerization ls usually only su~ricient to maintain the reaction mixture in liquid ~orm, although either superatmospheric or subatmospheric pressures can be used where such is advantageous. The con-centration o~ polymer~zable monomèrs in the polymerization mixture can be varied widely ~ith concentrations up to about 100% by weight and preferably from about 20 to about 70,0 by ~reight based on the weight of the polymerizatioll mixture, being satisractory. Suitable catalysts for the polymerization reaction include, for example, from about 0.1 to about ~.0 percent by weight, based on the total monomer weight, of a free radical catalyst, such as hydrogen peroxide, a salt Or peroxydisulfate, cumene hydroperoxide, water soluble azo type initiators and the like. In redox polymerization systems conventional ingredients can be employed, such as potassium persulfate and potassium meta bisulfite and others known in the art. If desired, the polyme~ can be lsolated rrom the reaction medium by rreezing, salting out, precipitation or any other procedure suitable for this purpose.
In some instances, it may be advanta~eous to include ~rom about 0.5 to about 4 percent by weight, based on the total monomer weignt, of a surface active a~ent or compatible 3 mixtures Or such agents in the preparation Or the copolymers _g_ -of the present invention. Suitable wetting agents include the non-ionic, ionic and amphoteric types as exemplified by the polyoxyalkylene derivatives, amphoteric amino acid dispersing agents, including sulfobetaines and the like.
Such wetting agents are disclosed in U.S. Patent 2,600,831, issued June 17, 1952, U.S. Patent 2,271,623, issu~d ~ebruary 3, 1942; U.S. Patent 2,275,727, issued March 10, 19112 and U.S. Patent 2,787,604, issued April 2, 1957;
U.S. Patent 2,816,920, issued December 17, 1957 and U.S.
Patent 2,739,891, issued March 27, 1956. Commercially-available surfactants such as DuPont's Duponal~ ME and Olin Mathieson's Surfactant lOG are also useful.
The compositionsof the present invention com-prise an aqueous dispersion of a copolymer as described hereinabove and a hydrophilic colloid and preferably proteinaceous colloids. Exemplary of such colloids include:
gelatin, protein derivatives, such as carboxymethylated proteins, colloidal albumin, cellulose derivatives, poly-(vinyl pyrrolidones) and other water soluble polymers.
20 The colloid usually comprises from about 10 to about 90 weight percent of the total composition weight.
In a preferred embodiment of the present inven-tion, the described compositions additionally comprise from about 30 to about 70 weight percent of the total composi-tion weight of a light sensitive silver hallde, such as silver chloride, silver bromide, silver chlorobromide, silver iodide, silver bromoiodide, and the like and ;~ -mixtures thereof. Dispersions of the photographic silver halide and the sulfonate copolymers described herein in combinakion with a hydrophilic colloid, such as gelatin, can be made in a variety of ways. ~or example, an aqueous gelatin dispersion of the photographic silver halide can be mixed with an aqueous dispersion or solu~ion of the sulfonate copolymer. Alternatively, the photographic silver . , .
. ~ ,, , halide can be preclpitated in an aqueous dispersion or solutiono~ the copolymer with or without another colloid, depend:lng upon the dispersion charaCteristics Or the copolymer. In thls case~ a ~ater-soluble salt such as silver nitrate is admixed with a water-soluble halide such as potassium bromide in the presence of the mixture. In still another procedure, the photographic silver halide is precipitated in an agueous gelatin solution and digested in the conventional manner known to the art. Arter digestion, but prior to coating there is added ~o the emulsion an aqueous dispersion of the copolymer. rhe bulk o~ the resultlng dispersion can be increased by the addition of more o~ the copolymers and/or natural or synthetic colloids or other binding agents suitable for use in photographic silver halide emulsions. Generally, the concentration of the copolymers described herein in the compositions o~ the p esent invention will be in the range of ~rom about 10 to about 90 percent by weight, more preferably in the range o~ about ~0 to about 60 percent weight, based on the total composition weight.
Where the compositions are used in photographic elements in layers other than the silver halide emulsion layers, for example~ in filter layers, antihalation layers, antiabrasion layers, antistatic layers, barrier layers, receiving layers for diffusion transfer processes and the like, they can be used as the sole vehicle or in admixture with natural or synthetic colloids such as are mentioned hereinberore.
The compositions described herein can be coated on a wide variety of supports, includin~ rilm bases such as pol;~ethylene terephthalate, cellulose acetate butyrate, polycarbonate, polyol~rins (e.g., polyethylene, polypropylene) 3 and the like. ~hen such film bases are used, the photoeraphic product obtained can be used, ~or example, as a transparency.
Ir desired, the compositions can be coated on an opaque support such as paper, polyolerin coated paper such as polyethylene or polypropylene coated paper which can be pigmented, wlth TiO2, ror example, the electron bornbarded or exposed ko a corona discharge to promote emulsion adhesion. When such supports are used, a color photographic print may be obtained.
The emulsions conkaining the copolymers described herein can be chemically sensitized with compounds o~ the sulfur group, noble metal salts such as gold salts, reduction sensitized with reducing agents, and combinations of .
these. The emulsion layer and other layers present in photo-graphic elements made accordi.ng to this invention can be hardened with any suitable hardener. Userul con-centrations Or hardeners are related to the amount of binder used and are known to those skilled in the art. Such hardened ~ayers will have a melting point in water greater than about 65~C and pre~erably greater than 90Co The emulsion can also contain addit~onal additives, 2~ particularly those known to be beneficial in photographic emulsions; including ror example, water-miscible and water-immiscible organic solvents~ stabilizers or antifoEgants, speed increasing materials, soluble inor~anic salts~
absorbing dyes, plasticizers and :

-the like. Sensitizers which ~ive particularly ~ood results in the photographic compositions disclosed herein are the alkenylene oxide polymers which can be employed alone or in combination with other materials, such as quaternary ammonium salts, as disclosed in ~.S. Patent 2,886,437 or with mercury compounds and nitrogen containing compounds, as disclosed in U.S. Patent No. 2,751,299.
The compositions described herein can be used in various kinds of photographic compositions and elements, including direct positive silver halide emulsions, x-ray and other non-spectrally sensitized emulsions as well as in orthochromatic, panchromatic and infrared sensitive emulsions~ particularly those sensitized with merocyanine dyes, cyanine dyes, carbocyanine dyes and the like.
~urthermore, these compositions can be used in emulsions comprising color forming materials or emulsions developed by solutions containing couplers or other color generating materials. In addition, they can be used in photographic emulsions containing developers, e.g., polyhydroxy-benzenes, as well as in emulsions intended for use in diffusion transfer processes which utilize the non- ~ `
developed silver halide in the non~image areas of the negative to form a positive by dissolving thè undeveloped silver halide and precipitating it on a receiving layer in close proximity to the original silver halide emulsion layer. Such processes are described in U.S. Patent 2,352,014 (Rott), U.S. Patent 2,543,181 (Land) and U.S.
Patent 3,020,155 (Yackel et al).
The sulfonate copolymers disclosed herein are useful in photographic image-transfer film units such as in image-transfer film units as described~ for example, in U.S. Patents 2,543,181; 2,983,606; 3g227~550~ 3,227,552;

3,415,6g5; 3,415,644; 3,415,646 ~, and 3,635,707; Canadian Patent 674,082; Belgian Patents 757,959 and 757,960, both issued April 23, 1971; Brit:ish Patents 904,364 and 840,731; and German Patent 2,242,762.
The compositions of the present invention can be used in individual layers of a multilayer photographic element over a broad range of coating coverages, e.g., from about 0.001 g/m2 to about 0.5 g/m2 of support, and preferably from about 0.05 g/m2 to about 0.3 g/m2 of support.
These compositions are ~articularly useful in color reversal-type photographic elements because the latex sulfonate copolymers incorporated therein impart a desirable decrease in the brittleness of the layers and a hue shi~t o~ the dyes in the elements. By hue shift is meant that the intensity and adsorp-tion maxima of the imaging dyes in the multilayers of photographic elements are shifted with a concurrent increase in speed and contrast relative to an element having the same multilayers but with no sulfonate copolymer.
The following examples are included for a further understanding of ~he present invention.

Pre~aration 1: Poly(butyl acrylate-co-styrene-co-sodium ~ 2-acrylamido-2-methylpropane sulfonate-co-methacrylamide) (;58. _25.2:8.0:8.0-wei-ght_ratio) This polymer latex was prepared by the following procedure:
Distilled water (528 kg) and Duponol ME*~(sodium lauryl sulfate surface active agent~ (1.7 kg) were added to a reactor vessel. This solution was thoroughly purged with nitro- ;;
gen and heated to about 90C with a slight nitrogen purge. ;
A 10~ by weight a~ueous solution of sodium 2-acryl-amido-2-methylpropane sulfonate (132 kg); surfactant Duponol ME*

*Trademark of E.I. DuPont de Nemours, Inc.

X

(1.7 kg); and methacrylamide (13.3 kg) were added to a head tank with moderate stirring. Butyl acrylate (100 kg) and styrene (42.~ kg) were then added to this and the monomer emulsion in the head tank was continuously stirIed for 20 minutes.
Potassium persulfate catalyst (0.85 kg) was added to the contents in the reactor vessel and the addition Or the emulsion in the head tank was begun within 2 mlnutes rollowing the catalyst addition. The emulsion was added to the reactor continuously over a 30 minute period. ~he reactor vessel contents were kept at g2-950c during this time. Following reaction of the monomer emulsion, the reactor contents were cooled to 85C and polymerization was allowed to proceed for 30 minutes.
After reaction, the temperature was rurther lowered to 7~C and residual monomer was removed by vacuum distillation.
The resulting latex was cooled to room temperature ~nd more distilled water (538 kg) was added with stirring. The latex was discharged through cheesecloth into storage containers.
The resulting latex had a percent solids o~ 12.2.
The isolated polymer had an inherent viscosity of 0.78 measured in ace~ic acid; and a glass transition temperature o~ ~-2C.

Preparation 2: Poly(butyl acrylate-co-styrene-co-sodium vinyl sulfonate-co-~thacrylamlde) (58 8:25.2-8:8 we~ rat_o) This copolymer was prepared in a similar ~ashion as the copolymer of Preparation 1 except that sodium vlnyl sulfonate was used as the sulfonate monomer instead Or sodium 2-acrylamido-2-methylpropane sul~onate. The isolated polymer had an inherent viscosity o~ 0.49 measured ln acetlc 3 acid and a glass transition temperature of ~1C.

Preparatlon 3: Poly(Methyl acrylate-co-styrene-co-sodium 2-acrylamido-2-methylpropane sulronate-co-meth rylarnide) (58 8:25.?:8 8 wei~_t ratio) This copolymer was prepared in a similar ~ashion 25 the copolymer Or Preparation 1 except that methyl acrylate was used instead of butyl acrylate. The isolated polymer had an inherent viscosity Or 0.72 measured in acetic acid, and a glass transition ternperature Or 60C.

Example 1: Stability o~ a Composition Cornpr~sing Gelakin ar~d Poly(butyl acrylate-co-styrene-co-sodium 2-acrylamido-2-methylpropane sulfonate-co rnethacrylamide) ~58.8:25.2:8.o:8.o weight ratio) This is a comparative example sho~ing the improved stability Or a composition of the present invention over a composition outside the teaching Or this invention. Table I
shows typical latex properties and stability test results of a composition comprising the sulfonate copolymQr of Preparatlon 1 compared to the latex properties and test results of a control latex composition comprising poly(butyl acrylate-co-styrene'-co- ' m~thacry~mi~e) (58.8:25.2:16 weight ratio) as prepared by the teaching Or U.S. Patent 2,739,137 (Fowler).
Light scatter was measured by diluting each Or the latex copolymers 1:10 with distilled water~ placing the diluted latex in a 1 cm cell and measuring the apparent absorbance in a Beckman DU spectrophotometer at 546 nm.
~olerance Or the gelatin-latex compositions to a typical organic solvent used in photographic compositions, such as methanol, was measured by incubating a mixture Or 5 g gelatin, 70 ml water, 20 ml methanol and 4.3 ml latex for 4 hours at 40C and microscopically evaluating the simulated melt ror - polymer coagulat~on at 645X magnirication. A microscopic rield with a clc-ar to rlne backeround and few visible coa~l~lum particles is desired. A tolerance Or 20 percent or more alcohol ls acceptable.
Tolerance Or the compositions to dissolved inorganic salts was measured by the light scatter technique arter the speciried room temperature incubation Or samples made up Or 97.5 g latex and ~.5 g o~ a typical salt, such as potassiurn bromide. Acceptable salt tolerance is indicated by an increase in apparent absorbance Or less than 50% with no caking.

o L') Il'~ ~r d' ~r d' O .......
~ O h O O O O O O O
r~ G) 3 ~1 t~

L') L,~', O
r~
CJ O ~ r` L~) _I h O ~ ~ ' ,Q ~ o a~ s o ~1 ~ Q~ a) t~
ra ~ X X X ~ ' E~ O -_1 0 r~
V ~ ~ U U t) ~J

.
a) ~ . .
h aJ
h ~ U
O) ~ ~
E ~-- h u) O
o ra L) u ,Q ~ 11 ~ ~J h h ~ r ~ S ,C rC ,~ ~: ~ ,C
O ::5 h ) I la ~I t l O aJ tl~ ~ Ul E X ~1 .
t;'' O ~-1 o d' \D ~1 ~D L'~
.Y r-l ~ O t~ ~ I
--( ~ U ~ L~) E-~
O O ~ ~ -; :

, .

In addition, similar tests applied to poly-(butyl acrylate-co-styrene-co-3-acryloyloxypropane-1-sulfonic acid~ sodium salt-co-methacrylamide) (58.8:25.2:8:8 weight ratio), which is similar to the copolymers taught in U.S. Patent 3,411,911 of Dykstra, showed that that prior art polymer was rapidly coagulated by a 2.5% KBr solution. Other copolymers which were unstable to the KBr solution include poly(butyl acrylate-co-styrene-co-styrenesulfonic acid, sodium salt-co-methacry~amide) (58.8:25.2:8:8 weight ratio) and poly(butyl methacrylate-co-sodium 2-acrylamido-2-methylpropane sulfonate-co-methacrylamide) (84:8:8 weight ratio).
These results show that the composition of the present invention comprising a sulfonate copolymer has improved stability to alcohols and dissolved salts over the latex compositions taught in the art.

Examples 2-4: Compositions Comprising Latex Polymers Having Varying Amounts of Sodium 2-Acrylamido~2-Methylpropane Sulfonate Monomer These are comparative examples.
Latex polymers were prepared having varying amounts of sodium 2-acrylamido-2-methylpropane sulfonate and methacrylamide according to the procedure of Prepara- ~;
tion 1. Compositions comprising each copolymer were evaluated for alcohol and potassium bromide tolerance using the techniques of Example 1 and compared to a control latex composition using a copolymer taught in U.S. Patent 2,739,137, notably poly(butyl acrylate-co-styrene-co-methacrylamide) (58.8:2~.2:1~ weight ratio). The results are shown in Table II.

n o o u) u~
. . ~1~ 3 ~ ~r ~ ~ ~ ~ ~
CO :~ O r~l Q) O O O O O O O
e.) tl~

~, I o ~ O o O O O O O O
~\ .

~ ~ ,C
r~ ~ ~ O o o o ~ ,~
a, o . ~, H ~
~I) C~ ro 1` 0 ~ '3 ' 'a .q .!J O D O C o ~ ~ ~ U U U U
c~ a) ~ E
S
1~ ~ C
E~ ~ .U V
~ O ~ n,~
U~ '3 ~: ~ C O U '~ 11 0 U
C ~ C ~
O >~ C t.) O t~) h .--1 h 11; 0 ~ t~ h ~1 ~ h h ~J U Q. ~ D ~ "~ X Q, ~ S ,C .C '- ,~ ' .C
O Y ~ O ~ O
3 3 o ~ a~ ~ o ~ ~D N ~D

' , r',~ b~,~

A~a~n, these examples show the improved stability to alcohol and dissolved salt Or the composit:ions Or the present invention over the eontrol composition taught in the art. Even small amounts of sodium 2-acrylamido~2~methylpropane sulfonate in the latex produce a marked increase in the composition stabil1ty.
Salt tolerance improves with increasing amounts oI the sulronate monorner in the interpolymer as ~nd~cated by lower absorballces and no eaking.

Example 5: Stabili~_Tests for he Copolymer o _Preparation 3 This is a eomparative exam~le.
The eopolymer Or Preparation 3 exhibited improved tolerance to alcohol and salt solutions over a control copolymer eomposition of poly(butyl acrylate-co-styrene-co-sodium 2-acrylamido-2~methylpropane sulfonate) (58.8:25.2:16 weight ratio) not eontaining methacrylamide, as indicated by the test results in Table III (the lower the ab~orbance, the greater the stability). The control copolymer had unacceptable tolerance to the KBr solution, i.e., an increase in absorbanee ~ 50%

- ~d4 ~ L

R~ h X ~ ~ o O O C~ O o O O

H ~1 H O
t~ h ;~
~ O ~ , o o ~
h C-~

Q~ .
h ~--O ~ ~ ~ C~ C~ .o S h S:: rd ~ h ~1 , o (1~ ~5 h r I h (~d o td h h ~ h h L~
H ~ J Ll~ O O
X ~1 0 ~ o ~ . . . !

Claims (13)

WHAT IS CLAIMED IS:

1. A composition useful for the preparation of flexible coatings which comprises an aqueous dispersion of a hydrophilic colloid and a copolymer having a glass transition temperature less than or equal to 60°C, characterized by said copolymer comprising:
A. from about 50 to about 70 percent by weight of an ester of an ethylenically unsaturated carboxylic acid monomer;
B. from about 2 to about 18 percent by weight of an amide of an ethylenically unsaturated carboxylic acid monomer;
C. from about 10 to about 30 percent by weight of a vinyl. benzene monomer; and D. from about 2 to about 18 percent by weight of a sulfonate monomer having, prior to polymerization, the formula (I):

( I) such that the total amount of amide and sulfonate monomers is less than 20 percent by weight of the total copolymer weight, wherein R is hydrogen or alkyl; R1 is selected from the group consisting of alkylene and -C-R2-; R2 is divalent amino substituted with alkyl or hydrogen, or -(CH2)nO- wherein n is an integer from 0 to 5, m is either 0 or 1; and X is hydrogen or a mono-valent cation.

2. A photographic composition comprising an aqueous dispersion of a light sensitive silver halide, a hydrophilic colloid and a copolymer having a glass transition temperature less than or equal to 60°C
characterized by said copolymer comprising:

A. from about 50 to about 70 percent by weight of an ester of an ethylenically unsaturated carboxylic acid monomer, B. from about 2 to about 18 percent by weight of an amide of an ethylenically unsaturated carboxylic acid monomer;
C. from about 10 to about 30 percent by weight of a vinyl benzene monomer; and D. from about 2 to about 18 percent of a sulfonate monomer having, prior to polymerization, the formula (I):

(I) such that the total amount of amide and sulfonate monomers is less than 20 percent by weight of the total polymer weight, wherein R is hydrogen or alkyl; R1 is selected from the group consisting of alkylene and -?-R2-; R2 is amino substituted with alkyl or hydrogen, or -(CH2)-nO-wherein n is an integer from 0 to 5; m is either 0 or 1;
and X is hydrogen or a monovalent cation.

3. The composition of claim 2 wherein the hydrophilic colloid is gelatin.

4. The composition of claim 2 wherein the ester is an alkyl ester of acrylic acid.

5. The composition of claim 2 wherein the amide is an amide of methacrylic acid.

6. The composition of claim 2 wherein the vinyl benzene is styrene.

7. The composition of claim 2 wherein the sulfonate has the formula:
wherein R is hydrogen or methyl; R2 is amino substituted with alkyl or hydrogen; and X is an alkali metal cation.

8. A photographic composition comprising an aqueous dispersion of a light sensitive silver halide, a proteinaceous hydrophillic colloid and a copolymer having a glass transition temperature less than or equal to 60°C characterized by said copolymer comprising:
A. from about 50 to about 70 percent by weight of an alkyl ester of acrylic acid;
B. from about 2 to about 18 percent by weight of an amide of methacrylic acid;
C. from about 10 to about 36 percent by weight of styrene; and D. from about 2 to about 18 percent by weight of a sulfonate monomer having, prior to polymerization, the formula such that the total amount of amide and sulfonate monomers is less than 20 percent by weight of the total polymer weight wherein R is hydrogen or alkyl; R2 is amino substituted with alkyl or hydrogen; and X is hydrogen or an alkali metal cation.

9. The composition of claim 8 wherein the proteinaceous hydrophilic colloid is gelatin.

10. A photographic composition comprising an aqueous dispersion of a light sensitive silver halide, gelatin and a copolymer having a glass transition temperature less than or equal to 60°C characterized by said copolymer comprising:
A. from about 50 to about 70 percent by weight of butyl acrylate;
B. from about 2 to about 18 percent by weight of methacrylamide;
C. from about 10 to about 30 percent by weight of styrene; and D. from about 2 to about 18 percent by weight of sodium 2 acrylamido-2-methylpropane sulfonate, such that the total amount of amide and sulfonate monomers is less than 20 percent by weight of the total polymer weight.

11. A photographic element which comprises a support having thereon at least one silver halide emulsion layer and at least one layer comprising an aqueous dispersion of a hydrophilic colloid and a copolymer having a glass transition temperature less than or equal to 60°C characterized by said copolymer comprising:
A. from about 50 to about 70 percent by weight of an ester of an ethylenically unsaturated carboxylic acid monomer;
B. from about 2 to about 18 percent by weight of an amide of an ethylenically unsaturated carboxylic acid monomer, C. from about 10 to about 30 percent by weight of a vinyl benzene monomer; and D. from about 2 to about 18 percent by weight of a sulfonate monomer having, prior to polymerization, the formula (I):

(I) such that the total amount of amide and sulfonate monomers is less than 20 percent by weight of the total polymer weight, wherein R is hydrogen or alkyl; R1 is selected from the group consisting of alkylene and -?-R2-; R2 is amino substituted with alkyl or hydrogen, or (CH2)nO-wherein n is an integer from 0 to 5; m is either 0 or 1;
and X is hydrogen or a monovalent; cation.

12. A photographic element which comprises a support having thereon at least one silver halide emulsion layer and at least one layer comprising an aqueous dis-persion of a proteinaceous hydrophilic colloid and a copolymer having a glass transition temperature less than or equal to 60°C characterized by said copolymer compris-ing:
A. from about 50 to about 70 percent by weight of alkyl ester of acrylic acid;
B. from about 2 to about 18 percent by weight of an amide of methacrylic acid;
C. from about 10 to about 30 percent by weight of styrene; and D. from about 2 to about 18 percent by weight of a sulfonate monomer having, prior to polymerization, the formula such that the total amount of amide and sulfonate monomers is less than 20 percent by weight of the total polymer weight, wherein R is hydrogen or alkyl; R2 is amino substituted with alkyl or hydrogen, and X is hydrogen or an alkali metal cation.

13. A photographic element which comprises a support having thereon at least one silver halide emulsion layer and at least one layer comprising an aqueous dis-persion of gelatin and a copolymer having a glass transi-tion temperature less than or equal to 60°C characterized by said copolymer comprising:
A. from about 50 to about 70 percent by weight of butyl acrylate;
B. from about 2 to about 18 percent by weight of methacrylamide;
C. from about 10 to about 30 percent by weight of styrene; and D. from about 2 to about 18 percent by weight of sodium 2-acrylamido-2-methylpropane sulfonate, such that the total amount of amide and sulfonate monomers is less than 20 percent by weight of the total polymer weight.