Note: Descriptions are shown in the official language in which they were submitted.
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-
4--
~'
.,
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
--5--
~ . . . . .
.. . . .
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
-1 O-
. , .
. ~ ,,
,
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
:
-12-
-
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
- 13 -
~,
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.
-14-
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
-16-
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.
-19-
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 ~
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~J U Q. ~ D ~ "~ X Q, ~ S ,C .C '- ,~ ' .C
O Y ~ O ~ O
3 3 o ~ a~ ~ o ~ ~D N ~D
'
,
--20--
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%
-21-
- ~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
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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 ~ . . . !
-22-
