[0001] This invention relates to acidic adhesive compositions which are useful in the image-recording
field. In particular, it relates to mask adhesive compositions which provide high
strength bonds in image-forming elements while greatly improving border quality around
image areas. This invention also relates to image-recording elements and particularly
to self-processing film units, containing such adhesive compositions.
[0002] Image-recording elements having a mask that forms a border and includes, at least
in part, a latent or visible image, are well known in the photographic art. Typical
elements of this type are self-processing photographic products which are generally
referred to in the photographic art as diffusion transfer, image transfer or instant
photographic film units.
[0003] In some of these units, an image-receiving layer provides a viewable image and can
be separated from an image-recording layer(s) after processing. In others, the image-receiving
layer(s) can remain permanently attached and integral with the image-recording layer
and layers ancillary thereto when a transparent support is employed on the viewing
side of the unit. After exposure of the film unit, an alkaline processing composition
permeates the various layers to initiate development of the exposed image-recording
layers. This processing composition can be introduced from outside the film unit or
from a container or rupturable pouch associated with the film unit. In most instances,
conventional darkroom processes and after-treatments, such as washing and stabilization
are not needed to provide an acceptable image since the film unit is fully self processing.
[0004] In a typical self-processing photographic film unit the mask is a thin framing means
which is bonded to layers or components above and below it with various adhesives.
For example, U.S. Patent 3,256,090 issued June 14, 1966, describes the use of encapsulated,
low-strength adhesives to temporarily bond the mask to an image-receiving layer while
acidic polyester mask adhesives that provide permanent bonds in film units are described
in U.S. Patent 4,097,282 issued June 27, 1978, and non-acidic polyester mask adhesives
are described in U.S. Patent 4,113,493 issued September 12, 1978. The mask provides
a border around an aperture which is adapted to receive the alkaline processing composition.
The border also defines an image, or picture area. Usually, the mask is located between
and around the edges of two components of the film unit (e.g. cover sheet and photosensitive
element) to provide a space or cavity between the components for the processing composition.
The edge of the mask around the aperture restricts the processing composition to the
image area and confines the resulting image to such area.
[0005] It has been the aim of workers in the photographic art to improve border quality
in image-recording elements, particularly the self-processing film units described
herein. Border quality denotes relative freedom from visible imperfections in the
border around the aperture. Such imperfections include lines, spots, stains and dye
deposits. Unfortunately, these workers have had very limited success in improving
border quality since a modification that may remove one imperfection may amplify another.
The addition of various materials to various layers of the film unit to reduce imperfections
is not always possible because such materials may cause sensitometric problems. Some
imperfections are caused by manufacturing procedures which cannot be adequately modified
to remove the imperfections.
[0006] A serious imperfection often found in the borders of prior art self-processing film
units is known as "border bleed". This imperfection causes the border to appear colored
(e.g. cyan) instead of white and to blend into the image area. Border bleed is believed
to result from the lateral migration of color- forming dyes or dye-providing materials
(e.g. dye releasers) from the image area into the border during or after processing
of image-recording layers. Such migration is accelerated when a film unit is subjected
to elevated temperatures (e.g. 30-60°C) or high humidity after processing for extended
periods of time.
[0007] Another imperfection observed in some film units after processing has begun is known
as "dark edge line". This imperfection is a single or series of parallel dark lines,
continuous or segmented, in the border at the edge of the image area. Dark edge line
apparently forms in the following way. When alkaline processing composition is introduced
into the image area, some of it moves laterally in the image-recording layers into
the border "under" the mask. Dyes are caused to be released by the composition as
it moves into the border. These dyes diffuse to the image-receiving layer and form
objectionable darkened deposits (e.g. dark lines) in the border at the edge of the
image area.
[0008] Dark edge line is intensified by the presence of air (in the form of "pockets" or
"bubbles") which can occur at the border-image area interface. Oxygen within the bubbles
causes dye to be released. This dye diffuses to the image-receiving layer and forms
dye deposits. The aforementioned air pockets or bubbles can result from nucleation
of bubbles at the mask-mask adhesive interface, or from voids in the adhesive. Bubble
nucleation and voids can result from nonuniform sealing between mask and image-recording
layers which often occurs during conventional manufacturing operations. Air bubbles
can also result when the manufactured film units are subjected to stress in handling,
shipping and use (e.g. twisting, bending, etc.). Such stressful conditions are very
difficult to monitor and control, especially after the film units are in the hands
of consumers.
[0009] The dark edge line imperfection becomes more pronounced when image development is
allowed to or necessarily proceeds for relatively longer periods of time (e.g. in
winter time or in colder climates). Yet such long development times may be desirable
or necessary in certain situations with certain image-recording materials.
[0010] Some reduction in border bleed has been achieved by adding certain acidic terpolymers
to gelatin interlayers or titanium dioxide reflective layers of self-processing photographic
film units, as described in Research Disclosure, publication 19146, March, 1980 (published
by Industrial Opportunities, Ltd., Homewell, Havant Hampshire P09 1 EF United Kingdom).
However, this reference fails to teach or suggest the present invention which provides
an improvement in overall border quality by simultaneously and significantly reducing
both border bleed and dark edge line imperfections. Moreover, we have determined that
positioning terpolymers in interlayers or reflective layers as described in the Research
Disclosure publication can undesirably lengthen access time, i.e. the time required
for image formation.
[0011] From the foregoing discussion, it is clear that there is a significant problem with
imperfections in the borders of image-recording materials (e.g. self-processing film
units). An improvement in border quality, particularly with regard to border bleed
and dark edge line, would obviously enhance the aesthetic qualities of processed film
units (i.e. finished prints) while permitting extended development or storage time
of unprocessed film units.
[0012] The present invention provides image-recording elements which exhibit excellent border
quality. This is achieved by the use of a new mask adhesive composition which simultaneously
provides high strength permanent bonds and improved border quality. This composition
is an acidic polymeric adhesive composition characterized in that it comprises a polymeric
acidic component having at least three milliequivalents of acid per gram of such component,
and a substantially immobile, blocked photographic development restrainer or a substantially
immobile, blocked competing photographic developer.
[0013] The image-recording elements of this invention which exhibit excellent border quality
comprise:
1) a support
2) a plurality of layers including an image-recording layer having an image area adapted
to be processed by an alkaline processing composition, and
3) a mask providing an aperture adapted to receive the qlkaline processing composition
and a border which defines the image area.
[0014] The mask is permanently bonded directly or indirectly to the image-recording layer
by a high strength adhesive composition which is disposed within the border and is
subject to contact with the alkaline processing composition.
[0015] This element is characterized in that the adhesive composition comprises a polymeric
acidic component that is adapted to neutralize the alkaline processing composition
in the border and has at least 3 milliequivalents to acid per gram of the acid component,
and a substantially immobile, blocked photographic development restrainer or a substantially
immobile, blocked competing photographic developer.
[0016] In self-processing image-recording elements prepared according to this invention,
the plurality of layers referred to in the preceding description can include an image-receiving
layer, as described herein.
Figure 1 is a front plan view of a self-processing film unit of this invention, partly
cut away to show a portion of the inner construction.
Figure 2 is a rear plan view of the film unit illustrated in Figure 1, partly cut
away to show portions of the inner construction.
Figure 3 is an exaggerated partial, sectional view taken along line 3-3 of Figure
2.
Figure 4 is a perspective view of equipment which does not form a part of this invention
but is used to determine bond strengths of adhesives adhering a mask and another material
as described in the following Examples.
[0017] As previously indicated, an essential ingredient of the adhesive compositions of
this invention is a polymeric acidic component which has at least 3 milliequivalents
of acid per gram of component. This component includes one or more acidic polymers.
As used herein the term "acidic polymer" refers to a polymer having acid groups, such
as carboxy, sulfo, phosphono or sulfino groups. Many such acidic polymers are known,
as described for example, in U.S. Patent 3,362,819 issued January 9, 1968, and Research
Disclosure, publication 13525, July, 1975 (published by Industrial Opportunities,
Ltd., Homewell, Havant Hampshire, P09 1 EF United Kingdom).
[0018] The acidic polymers useful in practicing this invention are typically condensation
or addition polymers which have the desired adhesive and neutralizing capabilities.
The adhesive compositions exhibit a bond seal strength of at least 441 N/m (450 g/cm),
and preferably at least 578 N/m (590 g/cm), as measured by performing 180° peel tests
on a commercially available Instron (trade mark) Tensile Tester, Model 1101 or 1130
(Instron Corp. of Canton, Mass., U.S.A.). Adhered samples for peel tests are prepared
in advance by sealing a mask material to various substrates such as a photosensitive
element, using heat and pressure. A more detailed description of the peel tests and
equipment used is given hereinafter immediately preceding the Examples.
[0019] The adhesive compositions of this invention are preferably used as mask adhesives
in image-recording elements where these adhesives are open or exposed to contact with
alkaline processing compositions. In other words, the mask adhesives are subject to
contact with the alkaline processing compositions during processing of the image area.
[0020] The acidic polymers useful in this invention generally have inherent viscosities
in the range of from 0.3 to 1.5, and preferably from 0.35 to 1.0, as measured at 25°C
in a suitable solvent, such as dioxane or a pH 5 buffer solution, at a concentration
of 0.25 g/dl of solution. For example, the inherent viscosities of poly(n-butyl acrylate-co-acrylic
acid) (30:70 weight ratio) and poly(n-butyl acrylate-co-2-acrylamido-2-methylpropane-sulfonic
acid) (25:75 weight ratio) used in the following Examples to illustrate the invention
were in the range of 0.55-0.75 in dioxane and 0.33-0.5 in a pH 5 buffer solution,
respectively. As used herein, inherent viscosity is determined by the formula:

where (η) is the inherent viscosity, ηµ is the relative viscosity, i.e. the viscosity
of a solution of the polymer in the solvent divided by the viscosity of the solvent
in the same units, and c is the concentration in grams of polymer per 100 ml. of solution.
[0021] A class of acidic polymers useful in this invention comprises from 5 to 90 percent,
often 45 to 85 percent, by weight, of units derived from one or more acidic monomers
of the formula (I):

wherein each of m and n is 0 or 1. Each of R and R
1 is hydrogen; methyl; halo, e.g. fluoro, chloro or bromo; or a monovalent acidic radical,
e.g. carboxy. Preferably, each of R and R
1 is hydrogen or methyl, and most preferably, each is hydrogen.
[0022] R
2 is oxy, carbonyl, carbonyloxy or carbonylimino. R
3 is a divalent aliphatic, alicyclic or aromatic radical containing carbon and hydrogen,
and optionally, oxygen atoms. More preferably, R
3 is a divalent hydrocarbon, typically of 1 to 20 carbon atoms, such as alkylene, arylene,
cycloalkylene, arylene- alkylene, alkylenearylene or arylenebisalkylene. Specifically,
R
3 can be alkylene, typically of 1 to 12 carbon atoms, such as methylene, ethylene,
propylene, 2,2-dimethyl-1,3-propylene, 1,1-dimethylethylene, 2-methyl-1,3-propylene
or decylene; or arylene, typically of 6 to 18 carbon atoms, such as phenylene, naphthylene
or xylylene.
[0023] R
4 is a monovalent acid radical, such as carboxy, sulfo, phosphono or sulfino; alkyl,
typically of 1 to 6 carbon atoms, e.g. methyl, 2-methylpropyl or hexyl; or alkoxycarbonyl,
typically of 2 to 7 carbon atoms, e.g. methoxycarbonyl. When R
4 is alkyl or alkoxycarbonyl, at least one of R or R
1 is a monovalent acid radical, such as carboxy.
[0024] Acidic monomers which are useful in the practice of this invention are acrylic acid,
methacrylic acid, aconitic acid, acryloyloxypropionic acid, citraconic acid, chlorofumaric
acid, fumaric acid, itaconic acid, maleic acid, a-methyl glutaric acid, crotonic acid,
2-acrylamido-2-methylpropanesulfonic acid, 2-methylacrylamido-2-methylpropane-sulfonic
acid, 3-acryloyloxy-butanesulfonic acid, vinylsulfonic acid, methacryloyloxyethyl-l-sulfonic
acid and p-styrene sulfonic acid. The acidic monomers useful herein are commercially
available or can be readily prepared by suitable techniques known to a person of ordinary
skill in the art.
[0025] In addition, the acidic polymers described hereinbefore can comprise from 10 to 95
percent, often 15 to 55 percent, by weight, of units derived from one or more additional
polymerizable, ethylenically unsaturated monomers. Any such monomer or monomers can
be used as long as the resulting acidic polymer has the neutralizing and adhesive
capabilities which have been described previously in this specification. The additional
monomer(s) can provide crosslinking capability to the polymer if desired.
[0026] Typical additional ethylenically unsaturated monomers are represented by the formula
(II):

wherein p is 0 or 1. Each of R
5 and R
6 is hydrogen, methyl or halo, e.g. fluoro, chloro or bromo. R
7 is carbonyl, carbonyloxy or carbonylimino.
[0027] R
s is hydrogen or a monovalent aliphatic, alicyclic or aromatic radical containing carbon
and hydrogen, and optionally, oxygen atoms provided, however, when R
s is hydrogen and p is 1, R
7 is carbonylimino. Preferably, R
s is a monovalent hydrocarbon, typically of 1 to 20 carbon atoms, such as alkyl, including
aralkyl, aryl including alkaryl, allyl or cycloalkyl. Most preferably, R
s is alkyl, typically of 1 to 12 carbon atoms, such as methyl, ethyl, isopropyl, n-butyl,
decyl or lauryl.
[0028] Exemplary monomers having formula (II) are n-butyl acrylate, trans-1,2-dichloroethylene,
2-norbornylmethyl methacrylate, ethyl 2-chloromethacrylate, methyl acrylate, n-lauryl
methacrylate, N-isopropylacrylamide, acrylamide and vinyl acetate. These monomers
are commercially available or can be readily prepared by suitable techniques known
to a person of ordinary skill in the art.
[0029] In practicing this invention, it is advantageous to use an adhesive composition comprising
an acidic polymer in which the acidic monomer units of the formula (I) are derived
from the class of sulfo-containing monomers having the formula (III):

wherein each of Rg and R
10 is hydrogen, methyl or halo; e.g. fluoro, chloro or bromo; R11 is oxy or imino; and
R
12 is alkylene, typically of 1 to 12 carbon atoms, e.g. methylene, ethylene, propylene,
trimethylene, 1,1-dimethytethytene, 2,2-dimethyl-1,3-propylene, 2-methyl-1,3-propylene
or decylene or arylene, typically of 6 to 18 carbon atoms, such as phenylene, naphthylene
of xylylene. In comparison to the other acidic polymers described herein, these sulfo-containing
polymers provide adhesives that exhibit a significant decrease in heat sealing temperatures
without sacrificing the excellent border quality and bond strengths described herein.
This provides an improvement in heat sealing latitude which enables a user to achieve
marked reductions in manufacturing costs. For example, expensive changes in existing
sealing equipment are avoided. Also, such sulfo-containing polymeric adhesive compositions
make it possible for a user to seal less heat resistant materials. Further, and of
great significance to our energy-conscious society, one who uses these adhesive compositions
needs less energy for sealing operations. Moreover, the aforementioned improvement
in heat sealing latitude was quite unexpected since the sulfo-containing polymers
useful in this invention have considerably higher glass transition temperatures (Tg)
than acidic polymers, such as the carboxy-containing polymers described herein. In
view of this higher Tg, the sulfo-containing polymers would be expected to be sealed
at relatively higher temperatures. Yet, just the opposite is the case. As illustrated
in the following examples, particularly Examples 4 and 5; the adhesive compositions
containing sulfo-containing polymers as described herein, can be sealed at temperatures
which are significantly lower than the sealing temperatures used with compositions
containing other acidic polymers, e.g. carboxy-containing polymers. As used herein,
Tg can be determined by differential scanning colorimetry, as disclosed in Techniques
and Methods of Polymer Evaluation, Vol. 2, Marcel Dekker, Inc. N.Y. 1970.
[0030] Examples of monomers of formula (III) are 2-acrylamido-2-methylpropanesulfonic acid,
2-methacrylamido-2-methylpropane-sulfonic acid, 2-acrylamidoethanesulfonic acid, 3-acryloyloxy-
butanesulonic acid, 3-acryloyloxypropanesulfonic acid and 2-acryloyloxyethanesulfonic
acid. These and similar sulfo-containing monomers are commercially available or can
be readily prepared by suitable techniques known to a person of ordinary skill in
the art.
[0031] As previously indicated, acidic polymers useful in the adhesive compositions of this
invention can comprise units derived from two or more acidic monomers. A particularly
useful acidic polymer of this type has units derived from a carboxy-containing monomer
and a sulfo-containing monomer of formula (III). In such a polymer, it is preferred
that from 5 to 50 percent, by weight, of the units be derived from the sulfo-containing
monomers of formula (III). Examples of suitable sulfo-containing polymers of this
type comprise:
(a) from 5 to 50 percent, by weight, of units derived from a sulfo-containing monomer
of formula (III) described hereinabove;
(b) from 10 to 85 percent, by weight, of units derived from a carboxy-containing polymerizable
ethylenically unsaturated monomer; and
(c) from 10 to 40 percent, by weight, of an additional polymerizable ethylenically
unsaturated monomer, such as of formula (II) described hereinabove.
[0032] Representative acidic polymers useful in this invention are poly(methyl acrylate-co-acrylic
acid), poly(n-butyl acrylate-co-acrylic acid), poly(vinyl acetate-co-acrylic acid),
poly(n-lauryl methacrylate-co-acrylic acid), poly(n-butyl methacrylate-co-3-methacryloyloxypropanesulfonic
acid), poly(N-isopropylacrylamide-co-acrylic acid), poly(methyl methacrylate-co-n-butyl
acrylate-co-acrylic acid), poly(n-butyl acrylate-co-2-acrylamido-2-methylpropanesulfonic
acid) and poly(n-butyl acrylate-co-acrylic acid-co-2-acrylamido-2-methylpropanesulfonic
acid) poly(ethyl methacrylate-co-acrylamide-co-2-acrylamido-2-methylpropanesulfonic
acid), and poly(N-isopropylacrylamide-co-2-acrylamidoethanesulfonic acid).
[0033] The polymeric acidic component described herein can be a mixture of acidic polymers,
such as preferably, a mixture of one or more sulfo-containing polymers and one or
more carboxy-containing polymers, e.g. a carboxy-containing linear addition polymer.
Typical sulfo-containing polymers are those having units derived from one or more
monomers offormula (III). Such mixtures can contain from 1 to 99 weight percent, and
preferably from 30 to 80 weight percent of the sulfo-containing polymer(s), based
on total polymeric acidic component weight. A preferred mixture of acid polymers which
can be used in practicing this invention is a mixture of poly(n-butyl acrylate-co-acrylic
acid) with poly(n-butyl acrylate-co-2-acrylamido-2-methylpropanesulfonic acid).
[0034] The polymerization conditions which can be used for making polymers useful in this
invention are those commonly employed in condensation and addition polymerization
techniques known in the art. For the preferred addition polymers, these techniques
include suspension and solution techniques. In these techniques, polymerization temperature
is subject to wide variation as it depends upon several variables, but it is generally
in the range of from 20° to 120°C. The pressure employed in the polymerization, if
any, is usually only sufficient to maintain the reaction mixture in liquid form. The
polymerization can be carried out in a suitable vehicle, for example, in water or
mixtures of water with water miscible solvents, e.g. methanol, ethanol, propanol,
isopropanol or butanol, or in an organic solvent or in mixtures of organic solvents,
e.g. N,N-dimethylformamide, acetone, dimethyl sulfoxide, tetrahydrofuran or methoxyethanol.
Generally, the concentration of polymer in solution or suspension is up to 40%, by
weight, and preferably from 10 to 25%, by weight, based on the total weight. Suitable
catalysts include free radical catalysts, e.g. hydrogen peroxide, cumene hydroperoxide
or water-soluble azo type initiators. Suitable non-ionic, ionic and amphoteric surface
active agents can be used if desired. In redox polymerization systems, the conventional
ingredients can be employed. If desired, the polymer can be isolated from the reaction
medium by freezing, salting out, precipitation or any other suitable procedure.
[0035] The concentration of polymeric acidic component in the adhesive compositions of this
invention is generally in the range of from 70 to 96 percent and preferably, from
80 to 90 percent, by weight. In a dried adhesive layer of from 0.002 to 0.013 mm (0.1
to 0.5 mils) thick, the coverage of polymeric acidic component is generally from 2
to 12 g/m
2 (0.2-1.2 g/ft
2), and preferably from 3 to 7 g/m
2 (0.3-0.65 g/ft
2), of surface area. Although the polymeric acid component of the adhesive composition
must have at least 3 milliequivalents of acid per gram, such component preferably
has 3 to 12 milliequivalents of acid per gram. Accordingly, the specific polymeric
acids employed to illustrate the invention in the following Examples had acid contents
in the latter range. For example, the acid content of the poly(n-butyl-acrylate-co-acrylic
acid) (30:70 weight ratio) was 9.7 milliequivalents of acid per gram and the acid
content of the poly(n-butyl acrylate-co-2-acrylamido-2-methylpropanesulfonic acid)
(25:75 weight ratio) was 3.6 milliequivalents per gram.
[0036] The adhesive compositions of this invention also comprise, as essential ingredients,
a substantially immobile, blocked photographic development restrainer, a substantially
immobile, blocked competing photographic developer or mixtures of either or both.
[0037] Photographic development restrainers are known to be useful to restrain photographic
development. The restrainers useful in this invention are "blocked", meaning they
have a built-in blocking group which prevents activation of the restraining function
before contact with the processing composition. The restrainers useful in this invention
can have any suitable blocking group. Typically, when a blocked photographic development
restrainer is subjected to an alkaline environment, such as an alkaline photographic
processing composition, the blocking moieties are cleaved, providing activated photographic
development restrainers.
[0038] The restrainers useful in this invention are also "substantially immobile", meaning
they are immobilized to prevent their migration, to any appreciable extent, out of
the mask adhesive into other layers such as image-recording layers prior to their
activation. One conventional way of immobilizing the restrainer is to attach a ballasting
group. In some restrainers, the blocking group can also serve as a ballasting group.
[0039] Any suitable substantially immobile, blocked photographic development restrainer
can be used in practicing this invention, including those described in Research Disclosure,
publication 15162, p. 84, Column 1, November, 1976 (published by Industrial Opportunities,
Ltd., Homewell, Havant Hampshire, P09 1 EF, United Kingdom). Typical restrainers are
those described in U.S. Patent 4,009,029 issued February 22, 1977. Such restrainers
are represented by the formula (IV):

wherein R
i. is hydrogen, alkyl or substituted alkyl, typically of 1 to 8 cabron atoms, e.g. methyl,
ethyl, chloromethyl, isopropyl or hexyl, aryl or substituted aryl typically of 6 to
12 carbon atoms, e.g. phenyl, xylyl or naphthyl; and Z comprises the nonmetallic atoms
necessary to complete a 5- or 6-membered substituted or unsubstituted heterocyclic
ring. These heterocyclic rings can be single rings as opposed to fused or condensed
rings in which the atoms are members of more than one heterocyclic ring. Typical heterocyclic
nitrogen moieties represented by formula (IV) include triazoles (e.g. 1,2,4-triazoles)
benzimidazoles, pyrimidines, monoazoles (e.g. benzoxazoles or benzothiazoles) and
tetrazoles. The sub- stitutents which can be present on the alkyl, aryl or 5- or 6-membered
heterocyclic ring are subject to wide variation and naturally include those which
are known to those skilled in the art (or can be easily determined by simple experimentation)
to be substantially free of deleterious photographic effects. A detailed description
of specific substituents is clearly not essential for an understanding of this invention.
However, it appears appropriate to mention that such substituents can be hydrocarbon,
for example, alkyl or aryl or they can be non-hydrocarbon such as halogen or alkoxy.
Most preferably, the blocked development restrainers useful in this invention contain
a tetrazole nucleus, such as a phenyl- substituted tetrazole nucleus. One such preferred
substantially immobile, blocked development restrainer is 5-(2-cyanoethylthio)-l-phenyltetrazole.
[0040] Competing photographic developers are well known in the photographic art to develop
silver without causing dye release. Like the substantially immobile, blocked restrainers
discussed hereinabove, the competing photographic developers useful in this invention
are both substantially "immobile" and "blocked". In this form, they will not migrate
and will not be activated until contact with the processing composition.
[0041] Any suitable substantially immobile, blocked competing developer can be used in this
invention. Examples of suitable compounds are those described in U.S. Patent 4,201,578,
issued May 6, 1980. Upon contact with an alkaline processing composition, the ester
groups of these competing developers hydrolyze allowing the resulting hydroquinone
to take part in development. The described competing developers are represented by
the formula (V):

wherein G is hydrogen, -COR,
4 or ―SO
2R
14, and preferably hydrogen; and G' is ―COR
14 or ―SO
2R
14, and preferably -COR
14. R
14 is alkyl or substituted alkyl, typically of 1 to 20 carbon atoms, e.g. methyl, chloromethyl,
ethyl, isopropyl, t-butyl, decyl or lauryl; aryl or substituted aryl, typically of
6 to 12 carbon atoms, e.g. phenyl, xylyl or naphthyl as long as the compound can be
hydrolyzed to the corresponding hydroquinone. Preferably, R
14 is alkyl.
[0042] Y is hydrogen; alkyl or substituted alkyl, typically of 1 to 6 carbon atoms, e.g.
methyl, ethyl, isopropyl or t-butyl; alkoxy or substituted alkoxy, typically of 1
to 6 carbon atoms, e.g. methoxy or ethoxy; aryl or substituted aryl, typically of
6 to 8 carbon atoms, e.g. phenyl, m-tolyl or p-methoxyphenyl as long as the compound
will diffuse at a sufficient rate when the acyl or sulfonyl group or groups are hydrolyzed.
Preferably, Y is alkyl. The substituents which can be present on the alkyl, alkoxy
and aryl radicals in these competing developers are the same type as those present
on the alkyl and aryl radicals in the development restrainers. Accordingly, specific
substituents are those which do not cause any significant deleterious photographic
effects as exemplified by hydrocarbon radicals such as alkyl and aryl and non-hydrocarbon
radicals such as halogen and alkoxy.
[0043] Useful substantially immobile, blocked competing photographic developers include
hydroquinone diacetate, hydroquinone monohexanoate, hydroquinone monoacetate, t-butylhydroquinone
monoacetate, hydroquinone monobenzoate, p-methylsuEfonyloxyphenol, and p-tolylsulfonyloxyphenol.
A preferred compound is t-butylhydroquinone monoacetate.
[0044] The substantially immobile, blocked photographic development restrainer or substantially
immobile, blocked competing photographic developer is generally present in the adhesive
compositions of this invention in a concentration in the range of from 2 to 20 percent,
and preferably, from 5 to 10 percent, by weight based on total composition weight.
In a dried adhesive layer of from 0.002 to 0.013 mm (0.1 to 0.5 mils) thick, the coverage
of such blocked compounds is generally from 0.1 to 2 g/
M2 (10-200 mg/ft
2), and preferably from 0.15 to 0.75 g/m
2 (15-70 mg/ft
2), of surface area.
[0045] The adhesive compositions can also comprise various addenda commonly used in the
art to enhance bond strength, improve coatability, prevent sticking of the coated
material in roll form and provide surface texture and reflection properties. Typical
addenda include dyes, pigments, fillers, binders, polymer modifiers and waxes. Preferably,
the compositions comprise silica, generally in an amount to provide coverage of from
0.2 to 0.7 g/m
2 (20-65 mg/ft
2) of surface area. Examples of suitable adhesive compositions include:
1. Poly(n-butyl acrylate-co-acrylic acid), 5-(2-cyanoethylthio)-1-phenyltetrazole
and silica.
2. Poly(n-butyl acrylate-co-acrylic acid), poly(n-butyl acrylate-co-2-acrylamido-2-methylpropanesulfonic
acid), 5-(2-cyanoethylthio)-1-phenyltetrazole and silica. The weight ratio of the
carboxy-containing polymer to the sulfo-containing polymer in this composition is
preferably in the range of from 50:50 to 70:30.
3. Poly(n-butyl acrylate-co-acrylic acid-co-2-acrylamido-2-methylpropanesulfonic acid),
5-(2-cyano- ethylthio)-1-phenyltetrazole and silica.
[0046] The adhesive compositions described herein are formulated by any convenient method
of mixing whereby an acidic polymeric component, a substantially immobile, blocked
photographic development restrainer and/or a substantially immobile, blocked competing
photographic developer and any other desired addenda are mixed at ambient temperature
in a suitable organic solvent (depending upon boiling point) such as methanol or dimethylformamide,
at from 10 to 40 percent solids. A specific technique for formulating an adhesive
composition of this invention involves initially forming a solution of acidic polymer
e.g., poly(n-butyl acrylate-co-acrylic acid) in methanol at ambient temperature. A
separate solution of substantially immobile blocked development restrainer e.g. 5-(2-cyanoethylthio)-1-phenyltetrazole
is then formed by placing the restrainer in a common solvent, heating for a few minutes
at a temperature of approximately 120°C. to completely dissolve the restrainer and
then cooling to ambient temperature. The two solutions are then combined using high
agitation while adding silica to form the adhesive composition.
[0047] The adhesive compositions of this invention can be used in a wide variety of self-processing
image-recording film units, and particularly in self-processing photographic film
units. Typical formats of such film units are disclosed, for example, in U.S. Patents
2,543,181; 2,983,606; 3,362,819; 3,415,644; 3,415,646; 3,647,437; 3,635,707; 3,756,815;
Canadian Patents 674,082 and 928,559; and Research Disclosure, publication 17643,
paragraph XXIII, p. 30, December, 1978 (published by Industrial Opportunities, Ltd.,
Homewell, Havant Hampshire, P09 1 EF, United Kingdom). Preferred self-processing photographic
products are of the type described in U.S. Patents 4,042,395 issued August 16, 1977,
4,061,496 issued December 6, 1977, and 4,190,447 issued February 26, 1980. A typical
self-processing film unit has a photosensitive element, a cover sheet and a mask comprising
an aperture adapted to receive the processing composition. The photosensitive element
often comprises at least one image-recording layer and an image-receiving layer. The
mask is bonded to the photosensitive element by the adhesive composition of this invention.
Preferably, the film units comprise one or more radiation-sensitive, image-recording
layers and associated dye-providing layers.
[0048] In addition, such film units can also contain other layers, e.g. neutralizing layers,
timing layers, barrier layers, reflective layers, opaque layers, spacer layers, interlayers
and the like. The film units can be treated with an alkaline processing composition
to effect or initiate development. This processing composition can be supplied by
external means or by an internal means, such as a container or rupturable pouch containing
the processing composition, which is part of the film unit, as described, for example,
in U.S. Patent 4,188,219 issued February 12, 1980. In addition, the film units can
have means for collecting excess processing composition such as a trap element.
[0049] In general, the alkaline processing composition contains a developing agent, although
the composition can also be simply an alkaline solution when the developing agent
is elsewhere in the film unit. In the latter case, the alkaline solution activates
the incorporated developing agent.
[0050] The image-recording elements of this invention do not necessarily contain an image-receiving
layer. Such elements are not diffusion or image transfer film units. These elements
can be used alone for recording and viewing an image or as part of a self-processing
film unit. Typically, such an element comprises a support, a plurality of layers,
including an image-recording layer, e.g., a photosensitive silver halide layer, and
a mask. The adhesive composition of this invention is used to bond the mask to the
image-recording layer or an intervening layer.
[0051] A detailed description of the components of the photographic products described hereinbefore
and processes for using them are given in Research Disclosure, publication 15162,
November, 1976 (published by Industrial Opportunities, Ltd., Homewell, Havant Hampshire,
P09 1 EF, United Kingdom).
[0052] In bonding the mask to an appropriate layer in the elements and film units of this
invention, the acidic adhesive composition can be coated in one or more layers to
give the desired adhesive and photographic results. The acidic adhesive composition
can be used to directly or indirectly bond the mask to the image-recording layer.
For example, there may be intervening layers or other adhesives between the acidic
adhesive composition and the mask or between the acidic adhesive composition and the
image-recording layer. Within the meaning of this disclosure, such masks are permanently
bonded to such image recording layers. As used herein "permanently bonded" means that
the bonded layers and mask remain adhered together during ordinary usage. This is
opposed to "temporary bonds" that allow layers to be peeled apart for usage.
[0053] The mask is sometimes made of a material, e.g. a polyester, such as poly(ethylene
terephthalate), an organic-coated polymeric film or a laminate of a polymeric film,
metal foil and paper, to which the acidic adhesive composition does not readily adhere.
In such instances, it is advantageous to coat the mask with one or more "primers"
or subbing layers which improve adhesion between the mask and the adhesive composition
of this invention. Such priming is known and suitable primers include polyesters which
can be coated out of organic solvents such as toluene, tetrahydrofuran, dioxane or
chlorinated hydrocarbons.
[0054] A preferred primer for use in film units of this invention is a two-layer laminate.
This laminate comprises a polyester, such as poly[ethylene-co-tetramethylene (72.5:27.5,
molar ratio) azelate-co-terephthalate (47.5:52.5, molar ratio)], coated on the mask,
and poly(ethylene-co-vinyl acetate) coated on the polyester. The adhesive composition
of this invention is applied to the poly(ethylene-co-vinyl acetate).
[0055] Figures 1-3 illustrate a self-processing photographic film unit of the present invention.
Referring to Figures 1 and 2, film unit 10 comprises support 12 which has a textured
or glossy, substantially planar outer surface which forms the entire front or viewing
surface of film unit 10. Support 12 is provided with an image-receiving layer 42,
one or more reflective layers 44, one or more opaque layers 46 and one or more radiation-sensitive
image-recording layers 14, e.g. photographic silver halide layers, to form photosensitive
element 11 (see Figure 3). The visible image occupies the image area indicated by
dashed rectangle 16. The border occupies the area outside dashed rectangle 16.
[0056] Covering film 19 is provided with one or more neutralizing layers 48 and one or more
timing layers 50 to form cover sheet 18 (see Figure 3). Cover sheet 18 is arranged
in superposition with and connected to support 12 with intermediate sheet 20 and spacer
rails 30 and 32. Preferably, support 12 and cover sheet 18 are transparent to actinic
radiation so that film unit 10 can be exposed to actinic radiation from the side illustrated
in Figure 2 and viewed from the side illustrated in Figure 1.
[0057] Film unit 10 has a container or rupturable pouch 22 which can be of any suitable
type known in the art. Pouch 22 carries a suitable alkaline processing composition
capable of reacting with portions of radiation-sensitive, image-recording layer(s)
14 to produce a visible image. When appropriate pressure is applied to pouch 22, the
processing composition is discharged and spread between image-recording layer(s) 14
and cover sheet 18 in a manner known in the art. At the end of film unit 10, opposite
pouch 22, is trap element 24 having enough volume to receive and hold excess processing
composition.
[0058] Intermediate sheet 20 is a unitary, multifunction sheet member which extends between
and couples together support 12 and cover sheet 18. It also provides mask 26 which
forms exposure aperture 28. Further, intermediate sheet 20 provides pouch attaching
cover 34 and trap cover 36.
[0059] Mask 26 and spacer rails 30 and 32 provide requisite spacing between radiation-sensitive,
image-recording layer(s) 14 and cover sheet 18 for the alkaline processing composition.
Preferably, mask 26 and spacer rails 30 and 32 are opaque to actinic radiation. This
opacity can be provided either with opacifying agents in the mask and spacer rails
themselves or with an opaque layer coated thereon.
[0060] Referring to Figure 3, photosensitive element 11 comprises transparent support 12
which has thereon, in sequence, image-receiving layer 42, light reflecting layer 44,
opaque layer 46 and radiation-sensitive, image-recording layer(s) 14. Mask 26 is bonded
to element 11 with acidic adhesive 40. Primer layer(s) 38 provide(s) improved adhesion
between mask 26 and acidic adhesive 40. Acidic adhesive 40 is open to exposure to
alkaline processing composition when that composition is introduced into cavity 52
between layers 14 and 50. Spacer rail 32 is adhered to cover sheet 18 and mask 26
by any suitable ahesive (not shown) known in the art, such as a poly(ethylene-co-vinyl
acetate)-based adhesive. Alternatively, cover sheet 18 can be self-adhering to spacer
rail 32. Transparent cover sheet 18 comprises transparent covering film 19, which
has thereon, in sequence, acid neutralizing layer 48 and timing layer(s) 50.
[0061] Evaluation of the bond strength of the adhesive compositions of this invention was
made using the following procedure and equipment.
Preparation of peel samples
[0062] Poly(ethylene terephthalate) mask coated with the appropriate primer(s) and adhesive
compositions of this invention, and various substrates to which the mask was to be
bonded were cut into sample pieces 2.54x5.4 cm in size. Each mask sample was bonded
to a substrate sample at one end to form a peel sample between two heated jaws at
138 kPa (20 psi) jaw pressure and various jaw temperatures for 0.4 second. The sealed
area was 2.54x0.76 cm in size.
Post bond conditioning
[0063] Bonds were tested at different intervals after sealing to determine the effects of
aging on the strength of the adhesive compositions.
[0064] In the "fresh" test, peel samples were placed in a 24°C/50% relative humidity environment
for from 4 to 24 hours prior to peel tests under these conditions.
[0065] In the "one week natural aging" test, peel samples were placed in a 24°C/50% relative
humidity environment for one week prior to peel tests under these conditions.
[0066] In the "four day, 49°C/10% RH" test, peel samples were placed in a 49°C/10% relative
humidity environment for 4 days prior to peel tests at 24°C and 50% relative humidity.
[0067] In the "one day, 32°C/90% RH" test, peel samples were placed in a 32°C/90% relative
humidity environment for at least 24 hours prior to peel tests under these conditions.
Peel tests
[0068] Peel tests of the samples were performed with a commercially-available Instron Tensile
Tester (Instron Corp, of Canton, Mass., U.S.A.) in the following manner. Referring
to Figure 4, the entire substrate 100 of a peel sample was adhered to a vertical mounting
plate 102 on crosshead 104 with double adhesive pressure sensitive tape. The unsealed
end of the mask 106 was opened away from substrate 100 by 180° and fixed in pneumatic
jaws 108.
[0069] Crosshead 104 was then pulled downward away from jaws 108 at a rate of 25.4 cm/min.
The force required to break the seal between mask 106 and substrate 100 was recorded.
[0070] The following examples illustrate the practice of the present invention.
Examples 1 and 2
Bond seal strengths of adhesive compositions
[0071] These examples illustrate the bond seal strengths of two adhesive compositions of
this invention. These compositions were used to bond a poly(ethylene terephthalate)
mask to various substrates. The poly(ethylene terephthalate) mask was coated with
two primer layers prior to being coated with the adhesive composition. The first primer
layer was a coating of a polyester, poly[ethylene-co-tetramethylene (72.5:27.5, molar
ratio) azelate-co-terephthalate (47.5:52.5, molar ratio)], and the second layer was
a coating of a commercially available poly(ethylene-co-vinyl acetate)-based adhesive.
[0072] The adhesive composition of Example 1 comprised poly(n-butyl acrylate-co-2-acrylamido-2-methylpropanesulfonic
acid) 25:75 weight ratio) (0.1 g), poly(n-butyl acrylate-co-acrylic acid) (30:70 weight
ratio) (0.1 g) and 5-(2-cyanoethylthio)-l-phenyltetrazole (25 mg).
[0073] The adhesive composition of Example 2 was poly(n-butyl acrylate-co-2-acrylamido-2-methylpropanesulfonic
acid) (25:75 weight ratio) (0.2 g) and 5-(2-cyanoethylthio)-1-phenyltetrazole (25
g).
[0074] Each adhesive composition was coated over the primer layers at a coverage of about
2.25 g/m
2.
[0075] The substrate materials listed in Table I were as follows: A=typical gelatin-containing
silver halide emulsion layer of a photosensitive element of the type described in
Example 2 of U.S. Patent 4,061,496 issued December 6, 1977; B=typical timing layer
of poly(acrylonitrile-co-vinylidene chloride-co-acrylic acid); C=cellulose acetate
film; and D=polystyrene film.
[0076] The conditions of sealing and the resulting fresh bond seal strengths are listed
in Table I below. The data listed therein clearly illustrates that the adhesive compositions
provided high strength permanent bonds (greater than 441 N/m (450 g/cm)) at several
sealing temperatures when used to bond the primed mask to a gelatin-containing layer
and a timing layer. The adhesive compositions did not effectively bond directly to
cellulose acetate and polystyrene. However, the adhesive compositions form satisfactory
bonds with the cellulose acetate and polystyrene films when appropriate adhesion promoting
coatings are used.

Example 3
Bond seal strengths of adhesive composition
[0077] An adhesive composition of this invention was used to bond a primed mask of the type
described in Examples 1 and 2 hereinbefore to a conventional gelatin-containing overcoat
layer of a photosensitive element of the type described in Example 2 of U.S. Patent
4,061,496 issued December 6, 1977. The bond seal strength of this composition was
then determined in the manner described in Examples 1 and 2 hereinbefore except that
the coverage of acidic adhesive was 6.1 g/m
2.
[0078] The adhesive composition comprised poly(n-butyl acrylate-co-acrylic acid) (30:70
weight ratio) (5.6 g) and 5-(2-cyanoethylthio)-I-phenyltetrazole (490 mg). The conditions
of sealing and the resulting bond seal strengths under various keeping conditions
are listed in Table II hereinafter. The data from Table 11 illustrates that this adhesive
composition has high bond strength under most conditions when sealed at conventional
sealing temperatures. The bond strengths appear to increase with age and are advantageously
high at high use temperature and humidity conditions.

Examples 4 and 5
Heat sealability comparisons
[0079] As previously indicated herein; in this invention the sulfo-containing polymers provide
a significant decrease in heat sealing temperatures and improved heat sealing latitude
in comparison to other acidic polymers. This advantage is illustrated by this example
which is a comparison of three acidic components useful in this invention.
[0080] Each polymeric acid component was used to bond a primed mask of the type described
in Examples 1 and 2 hereinbefore to a gelatin-containing overcoat layer of a photosensitive
element of the type described in Example 2 of U.S. Patent 4,061,496 issued December
6, 1977. The bond seal strengths of each component were then determined in the manner
described in Examples 1 and 2 hereinbefore except that the coverage of component was
6.1
91m
2.
[0081] The component of Example 4 was poly(n-butyl acrylate-co-2-acrylamido-2-methylpropanesulfonic
acid) (25:75 weight ratio). The component of Example 5 was a 40:60 weight ratio mixture
of poly(n-butyl acrylate-co-2-acrylamido-2-methylpropanesulfonic acid) (25:75 weight
ratio) and poly-(n-butyl acrylate-co-acrylic acid) (30:70 weight ratio). A control
component contained poly(n-butyl acrylate-co-acrylic acid) (30:70 weight ratio).
[0082] The conditions of sealing (seal temperatures) and the resulting bond seal strengths
under various keeping conditions are listed in Table III hereinafter. The data from
Table III show that the sulfo-containing polymers of Examples 4 and 5 which are useful
in the adhesive compositions of this invention can be sealed over a broader range
of sealing temperatures (and particularly at lower sealing temperatures) compared
to the Control component while retaining their strength over most keeping conditions.
As shown in Table III, adhesive strength was lost by Example 4 after prolonged exposure
to extremely high humidity.

Examples 6-13
Bond seal strengths and photographic effects of adhesive compositions
I. Bond seal strengths
[0083] Several adhesive compositions of this invention were used to bond a primed mask of
the type described in Examples 1 and 2 hereinbefore to a gelatin-containing overcoat
layer of a photosensitive element of the type described in Example 2 of U.S. Patent
4,061,496, issued December 6, 1977. The bond seal strengths of these compositions
were determined in the manner described in Examples 1 and 2 hereinbefore except that
the coverage of acidic adhesive was 6.1 g/m
2. For comparison purposes, a known adhesive composition comprising non-acidic poly-(ethylene-co-vinyl
acetate) and designated Control A was similarly tested.
[0084] The adhesive composition of Example 6 comprised poly(n-butyl acrylate-co-2-acrylamido-2-methyl
propanesulfonic acid) (25:75 weight ratio) (5.2 g), 5-(2-cyanoethylthio)-1-phenyltetrazole
(420 mg) and silica (520 mg). The composition of Example 7 was similar except the
acidic polymer component was a 37.5:62.5 mixture (by weight) of poly(n-butyl acrylate-co-acrylic
acid) (30:70 weight ratio), and poly(n-butyl acrylate-co-2-acrylamido-2-methylpropanesulfonic
acid) (25:75 weight ratio). Examples 8, 9 and 10 were similar to Example 7 except
that the polymer mixtures were present in 50:50, 62.5:37.5 and 60:40 weight ratios,
respectively.
[0085] Examples 11-13 were similar to Example 6 except that poly(n-butyl acrylate-co-2-acrylamido-2-methylpropane
sulfonic acid-co-acrylic acid) was used instead of the copolymer. These terpolymers
were prepared from the appropriate monomers in weight ratios of 30:35:35, 30:31.5:38.5
and 30:28:42 for Examples 11-13, respectively.
[0086] The conditions of sealing and the resulting bond seal strengths under various keeping
conditions are listed in Table IV below. All of the adhesive compositions, including
the control provided high strength bonds over most keeping conditions. As shown in
Table IV, adhesive strength was lost in Examples 6-8 after prolonged exposure to extremely
high humidity.

II. Photographic effects
[0087] Several diffusion transfer film units of the type described in Example 1 of U.S.
Patent 4,061,496, issued December 6, 1977, were prepared. Several different adhesive
compositions were used to bond a primed mask of the type described in Examples 1 and
2 hereinabove to the gelatin-containing overcoat (referenced layer 12 in that Example)
of the photosensitive element. Each film unit was exposed to a test object and a processing
composition was spread between the photosensitive element and the cover sheet by a
pair of juxtaposed pressure rollers at either 16° or 22°C.
[0088] Some of the film units so exposed and processed were evaluated for border bleed.
These film units were subjected to a 60°C/40% R.H. environment for 16 hours. The amount
of border bleed was determined by measuring the increase in red, green and blue densities
with a conventional densitometer in the normally white borders of the film units.
The sensitometric data are listed in Table V below.
[0089] An evaluation of dark edge line is also presented in Table V.
[0090] In the data presented in Table V for dark edge line, an evaluation of 4 or less is
good and means that very little of that defect was observed. An evaluation of 5 or
6 is fair, but acceptable in quality. An evaluation of greater than 6 is poor and
indicates that dark edge line was so prominent that the image would likely be unacceptable
to users.

[0091] The data listed in Table V shows that the adhesive compositions of this invention,
when used as mask adhesives in self-processing film units, greatly improve border
quality in those film units. The improvement in border bleed is most prominently seen
in the reduction of red density since most border bleed is attributable to undesired
migration of cyan dye. That is, border bleed generally shows up as a cyan color in
the border. Density increases in the green and blue regions of the spectrum are also
reduced in most cases. The adhesive compositions of this invention also provide marked
reduction in dark edge line over the control adhesives at both processing temperatures
but especially at the lower processing temperature when dark edge line is usually
more prominent. The film units of this invention were consistently evaluated as 6
or less, and many units were evaluated as 4 or less.
[0092] Considering the data presented in Tables IV and V together, it is apparent that the
control mask adhesives provided high strength bonds, but were severely dificient in
photographic properties (i.e. exhibited significant border defects). In contrast,
the mask adhesives of this invention provide the needed high bond strengths while
significantly reducing defects in the border.