U.S. patent number 3,747,223 [Application Number 05/103,860] was granted by the patent office on 1973-07-24 for chemical composition and process.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to Paul W. Faulhaber.
United States Patent |
3,747,223 |
Faulhaber |
July 24, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
CHEMICAL COMPOSITION AND PROCESS
Abstract
A flexible, liquid permeable, drying element, such as a thin
coating, containing an organic desiccant, typically with a
synthetic, polymeric binding agent, is used for removing a liquid,
such as water, from a permeable solid, such as from one or more
layers of a photographic element containing water. For instance, a
thin coating of an organic desiccant, such as a mixture of ethylene
oxide polymers, removes a large percentage of the water from a wet
photographic emulsion layer. An inorganic desiccant and/or other
addenda can be present in the thin coating.
Inventors: |
Faulhaber; Paul W. (Rochester,
NY) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
|
Family
ID: |
26800942 |
Appl.
No.: |
05/103,860 |
Filed: |
January 4, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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693139 |
Dec 26, 1967 |
3591411 |
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Current U.S.
Class: |
34/353 |
Current CPC
Class: |
G03C
11/16 (20130101); B01J 20/00 (20130101); B01J
20/28042 (20130101); B41M 7/02 (20130101); B01J
20/2803 (20130101); G03D 15/00 (20130101) |
Current International
Class: |
B41M
7/02 (20060101); B41M 7/00 (20060101); B01J
20/28 (20060101); B01J 20/00 (20060101); G03D
15/00 (20060101); G03C 11/00 (20060101); G03C
11/16 (20060101); F26b 003/00 () |
Field of
Search: |
;34/9,95 |
References Cited
[Referenced By]
U.S. Patent Documents
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3384971 |
May 1968 |
Thomas, Jr. et al. |
|
Primary Examiner: Camby; John J.
Parent Case Text
This is a division of application Ser. No. 693,139, filed Dec. 26,
1967, now U.S. Pat. No. 3,591,411.
Claims
I claim:
1. In a process for removing a diffusible liquid from a permeable
solid containing said liquid by contacting said permeable solid
with a solid material which removes said liquid from said permeable
solid, the improvement comprising contacting said permeable solid
with a flexible, liquid permeable, drying element comprising a
solid coating containing as an organic desiccant poly(ethylene
oxide) having an average molecular weight of from about 190 to
about 20,000.
2. A process as in claim 1 wherein said permeable solid is a
photographic element.
3. A process as in claim 1 wherein said diffusible liquid is
water.
4. A process as in claim 1 wherein said solid coating comprises a
mixture of a poly(ethylene oxide) having an average molecular
weight of about 190 to about 20,000 and a high molecular weight
poly(ethylene oxide).
5. A process as in claim 1 wherein at least about 60 percent by
weight of said liquid is removed from said permeable solid
containing said liquid in about 1 to about 60 seconds at about
20.degree.C.
6. A process for removing moisture from a moist photographic
element comprising contacting said element with a solid coating
comprising a high molecular weight poly(alkylene oxide) having an
average molecular weight of at least about 100,000.
7. A process as in claim 6 wherein said solid coating comprises a
mixture of (a) poly(ethylene oxide) having an average molecular
weight of about 190 to about 20,000 and (b) high molecular weight,
highly crystalline poly(ethylene oxide) having an average molecular
weight between about 100,000 and about 5,000,000.
8. A process as in claim 7 wherein moisture is removed from a moist
photographic element by contacting said element for up to about 60
seconds under ambient conditions of temperature, pressure and
humidity with a paper support having a solid coating comprising
said mixture about 0.01 to about 1.0 millimeters thick to remove at
least about 90 percent by weight of said moisture.
Description
This invention relates to removing liquids from permeable solid
materials containing such liquids. In one of its aspects, it
relates to removing diffusible liquid, such as water, from liquid
permeable solid materials, such as a moist layer of a photographic
element. In another of its aspects, it relates to drying a moist
colloid coating by contacting the moist coating with a supported or
unsupported coating containing an organic desiccant.
Two methods have generally been employed heretofore for removing
liquids from permeable solids containing such liquids. In one
method, liquid is removed by evaporation, for example, by a
combination of heating the solid and/or reducing the pressure
around the solid material. In the second method, the solid material
is immersed in an extractant, such as removing moisture from a
moist photographic element by immersing the moist element in an
extractant as set out in U. S. Pat. No. 2,150,757 -- Bodine, issued
Mar. 4, 1939.
These methods have not been satisfactory in many cases, especially
for removing moisture from photographic elements, since they
require costly equipment, such as apparatus for forcing heated air
over the solid material, required excessive time, often leave
undesirable residue on the solid dried, make the elements
susceptible to accumulation of dust, and/or cause undesirable
changes in the material dried.
In the case of photographic elements, it has been usual practice to
process such elements after exposure in solutions or processing
baths which produce a wet or moist product. It has been necessary
in such cases to wait, often for many minutes, for the film, paper,
or the like, to dry before further processing or handling, such as
contact printing, can be carried out. This time can be reduced by
forced air drying at elevated temperatures but this method has not
been entirely satisfactory for removing diffusible liquid from a
photographic element in a matter of seconds without undesired
affects to the element.
Drying of photographic elements processed without use of
conventional processing baths and where inspection of the processed
element as soon as possible is desirable has been especially
important. For example, in aerial reconnaissance, in radiology, and
the like, it is necessary to have the processed photographic
element in dry condition as soon as possible to determine results,
to determine whether another exposure should be made, and/or for
other purposes. One method which has been advantageous in
decreasing the time from exposure to finished product, without the
use of conventional processing baths, employs a wet or moist
absorbent web containing processing compounds, typically a
monobath, which is contacted with the exposed element for a desired
length of time. This method and means for carrying out the method
are set out, for example, in U.S. Pat. 3,179,517 -- Tregillus et
al., issued Apr. 20, 1965. One disadvantage of this method,
however, is that the resulting processed photographic element is
moist, as in other processes, after the film and web are separated
and usually must be dried in some manner. Efforts to dry such a
photographic element have included application of a powdered
inorganic drying agent, such as barium oxide, calcium chloride,
activated alumina, and the like, dusted over the surface of the
moist element or located on the surface opposite the film of a
protective porous web which is contacted with the moist film. This
is disclosed in British Pat. No. 1,012,391, issued sued Dec. 8,
1965. In the case where the inorganic drying agent is dusted over
the surface of the moist photographic element, undesired adherence
of the inorganic drying agent to the surface of the element can
occur. On the other hand, when the moist photographic element is
contacted with a semi-permeable membrane which in turn is contacted
with an inorganic drying agent, additional means can be required
for contacting the semi-permeable membrane with the inorganic
drying agent and removal of moisture can be less efficient than in
the case of direct contact of the inorganic drying agent with the
moist element.
No process or means has been completely satisfactory heretofore for
eliminating the costly air drying steps and apparatus employed for
removing moisture or other liquids from a moist layer of a
photographic element with direct contact of drying means on the
layer.
Accordingly, an object of the invention is to provide novel means
for rapidly removing liquid, such as water, from a permeable solid,
such as a layer of a photographic element, containing such liquid
without undesired changes in the solid.
Another object is to provide a novel composition for removing a
liquid, such as water, from a permeable solid, such as a
photographic emulsion coating, by contact of the composition with
the permeable solid.
A further object is the provision of a means for rapidly removing
diffusible liquid, such as water, from a photographic element
without leaving undesirable residue on and/or in the element.
The invention, accordingly, comprises means, compositions and
processes for rapidly removing liquid from a permeable solid
material containing such liquid by contacting, preferably directly
contacting, such permeable solid material with a flexible, liquid
permeable, drying element comprising a solid coating containing an
organic disiccant, without leaving undesirable residue and without
adverse effects to the solid material.
One embodiment of the invention, accordingly, comprises a flexible,
liquid permeable, drying element comprising an organic desiccant in
a synthetic polymeric binding agent different from said organic
desiccant, e.g. having higher molecular weight or being different
in composition.
This flexible, liquid permeable, drying element has the properties
of (a) removing liquid from a permeable solid material containing
such liquid when the drying element and permeable solid material
are in contact, and (b) after contact, leaving little residue on
the permeable solid material.
Another embodiment comprises a flexible, liquid permeable, drying
element which is a substrate having on at least one surface a thin,
adherent, liquid permeable coating of an organic desiccant in a
synthetic polymeric binding agent different from said organic
desiccant.
A drying element of the invention typically has the property of
transferring no more than about 20 milligrams per square foot of
both said organic desiccant and said binding agent to a wet gelatin
coating upon contact with said coating for up to about 6 seconds.
It also typically has the property of removing at least about 60
percent, for instance, more than about 85 percent, by weight of
water from a wet gelatin layer coated on a substrate upon
contacting said layer for a period of no more than about 60 seconds
with said drying element.
For instance, a drying element according to the invention can
comprise a support, typically a flexible support, having a solid,
polymeric coating comprising an organic desiccant, which is a
poly(alkylene oxide), with a polymeric binding agent different,
e.g. having higher molecular weight or being different in
composition, from said organic desiccant. An especially useful
drying element, according to the invention, comprises a flexible
support having a solid, polymeric coating comprising a poly
(ethylene oxide) having an average molecular weight of about 190 to
about 20,000 with a high molecular weight poly(ethylene oxide)
binder, e.g. having an average molecular weight of about 100,000 to
about 5,000,000 or more. An especially useful drying element
according to the invention comprising a flexible support, such as
paper or a polyethylene terephthalate film, having a thin adherent
coating of about 10 percent by weight poly(ethylene oxide) having
an average molecular weight of about 6,000 to about 7,500 with
about 90 percent by weight of high molecular weight poly(ethylene
oxide) e.g. having an average molecular weight of about 100,000 to
about 5,000,000, can remove at least about 90 percent by weight of
the water from a moist gelatin layer coated on a substrate upon
contacting said layer for a period of no more than about 60 seconds
with said drying element.
The material comprising the organic desiccant and/or binder, if one
is used, need not be present only on the surface of the support, if
one is employed. It can be present in and/or on the support. For
example, part of the organic desiccant in the case of a
poly(alkylene oxide) and/or binder can be present in the support.
The entire amount of these materials can be in the support or the
entire amount can be on the surface of the support if desired.
Also, if desired, one or more of such materials can be coated on
one or more sides of a support, including the edges in the case of
paper or film, for instance.
In some cases, a coating, according to the invention, has
sufficient strength that a support is not needed. Accordingly, the
word coating as employed herein is intended to include both
supported and unsupported coatings. Unsupported coatings include,
for example, self-supporting webs, sheets, films, tape, and the
like. Use of a support is often advantageous, serving as a
reservoir for liquid removed from the permeable solid. For
instance, a paper support coated with a polymeric coating according
to the invention can hold a significant amount of moisture more
than the coating alone.
Any suitable coating thickness can be employed. The coating
thickness can vary over a wide range depending upon the material to
be dried, the composition of the coating, the type of support if
one is employed, the amount and type of liquid to be removed from
the permeable solid material, and the like. A suitable thickness
comprises about 0.001 millimeter to about 1.0 millimeter, typically
about 0.01 to about 0.5 millimeter, but a thickness outside this
range can be used.
A wide range of binders can be employed in and/or on the drying
elements of the invention. In general, any binding agent can be
employed with the organic desiccant of the invention which provides
a solid coating, under ambient conditions, and which does not
adversely affect the properties of the drying element, e.g. does
not hinder liquid removal properties of the drying element and
leaves little or no undesirable residue on the material from which
liquid is removed.
The binder can be a desiccant. That is, if desired, both the
organic desiccant and the binder can effect removal of liquid from
a permeable solid containing such liquid. The organic desiccant
can, but need not be, the same as the binder. For instance, in the
case of poly(ethylene oxide), if the poly (ethylene oxide) is
sufficiently solid, e.g. has sufficiently high molecular weight,
under ambient conditions, it need not be employed in combination
with a binder, such as a poly(ethylene oxide) having an average
molecular weight of about 100,000 to about 5,000,000. In this case,
the organic desiccant can be used alone without a binder.
If a poly(ethylene oxide) having an average molecular weight of
about 190 to about 20,000 is employed as the organic desiccant
according to the invention, it is usually desirable, and often
necessary to employ a binder therewith, such as a binder which is a
poly(ethylene oxide) having an average molecular weight of about
100,000 to about 5,000,000. The presence of the binder can aid in
prevention of transfer of undesired residue to the material from
which liquid is removed, such as transfer of undesired
concentrations of poly(ethylene oxide) to a layer of a photographic
element from which water is removed. It can also aid in the removal
of liquid.
The binder can be employed in any suitable concentration depending
on the components of the drying element, the support, if one is
employed, the material from which liquid is to be removed, the
conditions under which liquid is to be removed, and the like.
Usually about 10 percent by weight to about 95 percent by weight
binder in a coating according to the invention is sufficient. In
the case of a coating containing about 10 percent by weight of a
poly (ethylene oxide) having an average molecular weight of about
6,000 to about 7,500 about 90 percent by weight of a poly-ethylene
oxide) having an average molecular weight of about 100,000 to about
5,000,000 is especially suitable as a binder where moisture is to
be removed from a moist layer of a photographic element.
Typical binders include polymeric binders, for example, natural and
synthetic polymers. Polymers as employed herein includes
homopolymers, copolymers, terpolymers, and other polymeric
materials as well as mixtures thereof. It includes polymeric
materials. Mixtures of two or more binders can be employed in a
wide range of ratios. The polymeric binder must be sufficiently
solid and must have sufficient film forming properties to form
coatings with an organic desiccant according to the invention.
Examples of typical binders include natural and synthetic resins,
such as poly(ethylene oxide) having an average molecular weight of
about 100,000 to about 5,000,000; polyvinyl alcohol; poly(acrylic
acid esters), e.g., poly(methylmethacrylate); carboxyl derivatives
of cellulose; vegetable gums; cellulose esters; polyvinyl ethers,
and silicones.
Examples of suitable materials which can be employed in the
practice of the invention as binders and/or as organic desiccants
are disclosed, for example, in French Pat. No. 1,482,699, issued
Apr. 17, 1967. Specific examples of materials which can be employed
in the practice of the invention as binders and/or as organic
desiccants, depending on the properties described, are as
follows:
1. Poly(ethylene oxide), usually available as mixtures having an
average molecular weight of about 900 to about 20,000. Compounds of
this type are available under the trade name, Carbowax, from Union
Carbide Corporation, New York, New York.
2. Poly(ethylene oxide), having a molecular weight of at least
about 100,000 and having a narrow melting point range, e.g. about
65.degree.C. Compounds of this type are commercially available
under the trade name, Polyox, from Union Carbide Corporation, New
York, New York.
3. Poly(acrylamide) and related polyamides, such as those having an
average molecular weight of at least about 900, e.g. 900 to
5000.
4. Polyvinylpyrrolidones, such as those having an average molecular
weight of at least about 900, e.g. about 900 to about 40,000 or
more.
5. Alkylene oxide-silicone copolymers. Compounds of this type are
available from the Union Carbide Corporation, New York, New York
under the trade name, Silicone Polymers L-250, L-530, and the
like.
6. Ethylene oxide-propylene oxide copolymers in which the ethylene
oxide comprises at least 40 percent by weight of the copolymer,
such as those having an average molecular weight of at least about
900, e.g. about 900 to about 20,000. Compounds of this type are
available under the trade name Pluronic from Wyandotte Chemical
Company, Wyandotte, Michigan.
7. Polyvinyl glycols, such as those having an average molecular
weight of at least about 900, e.g. about 900 to 9,000.
8. Urethane resins, such as those having an average molecular
weight of at least about 900. Compounds of this type are available,
for instance, from the Dow Chemical Company, Midland, Michigan
under the trade name, Voranol.
9. Polyacryloxy sulfonic acids, such as those having an average
molecular weight of at least about 900. Compounds of this type can
remove water from layers of a photographic element, i.e. they can
be an organic desiccant and/or a binder according to the
invention.
10. Vinyl ether-maleic anhydride copolymers, such as those having
an average molecular weight of at least about 900. Compounds of
this type are available from General Aniline and Film Corporation,
New York, New York, under the trade name, Gantrez Resin AN-119.
11. Copolymers of acrylamide with 2-acetoacetoxyethyl methacrylate,
e.g. those containing 90% by weight acrylamide.
While various polymeric coatings can be used for removing
diffusible liquid according to the invention, especially poly
(ethylene oxide), having an average molecular weight of about 190
to about 5,000,000 are especially suitable, for instance, (a)
alone, (b) as a binder, (c) part of a mixture of binders or (d)
part of a mixture of drying agents and binders.
High molecular weight poly(alkylene oxide) as employed herein means
such compounds having an average molecular weight well above
20,000, e.g. above the highest average molecular weight of
poly(ethylene oxide) sold under the trade name, Carbowax, by the
Union Carbide Corporation, New York, New York, and typically at
least about 100,000, e.g. about 100,000 to about 5,000,000 or
more.
Highly crystalline, as employed herein, means that the polymer in
the solid state has a sharp melting point, e.g. about 65.degree.C.
for high molecular weight poly(ethylene oxides). The degree of
crystallinity can typically be measured using nuclear magnetic
resonsance techniques.
A coating of the invention can contain an inorganic desiccant. Any
suitable inorganic desiccant can be employed which does not
adversely affect the material dried, does not leave an undesirable
residue and does not adversely affect the removal of liquid by the
coating of the invention. For example, the inorganic desiccant set
out in British Pat. No. 1,012,391 or inorganic drying agents known
in the art as molecular sieve materials can be employed in
combination with an organic desiccant of the invention. Suitable
molecular sieve materials are discribed, for example, in an article
by Rene Petit (University of Paris), in Chim. Anal. (Paris), Volume
47, No. 12, pages 643 to 656 (1965).
The addition of molecular sieve materials according to the
invention can produce an advantageous reduction in possibly
undesirable adhesion of a coating of the invention to the materials
from which diffusible liquid is to be removed. For example, the
addition of a crystalline alumino silicate molecular sieve material
to a coating of the invention can produce a pronounced decrease in
adhesion of a coating of the invention to a photographic element.
The concentration of inorganic desiccant and/or method of
preparation of a coating according to the invention containing an
inorganic desiccant can vary depending upon components in the
coating, the material to be dried, the type of support, if one is
employed, and the like. In general, less than about 90 percent by
weight, e.g. about 0.01 percent to about 50 percent by weight of
the total coating is inorganic drying agent. The inorganic drying
agent can be admixed in a coating composition before coating on a
suitable support, if one is employed, can be applied to or prepared
in the support before application of other components of the
coating can be applied in a separate layer or can be applied in any
suitable manner.
The invention is useful for drying and/or removing diffusible
liquid from a wide range of permeable solid materials containing
such liquid. For instance, the elements, compositions and processes
of the invention can be used for drying or removing liquid
from:
a. textile fibers and/or fabrics, such as removing moistrue from
moist natural or synthetic fibers;
b. coatings of various types, such as removing moisture from a
moist gelatino coating; or
c. inked or printed surfaces, such as surfaces where ordinary ink
blotters are useful. In removing diffusible liquids from such
materials, it is important that the material to be dried be
intimately contacted with the materials according to the invention
which effect removal of the liquid.
A semi-permeable membrane material, such as a thin sheet of
cellophane, can be used between the permeable material from which
diffusible liquid is to be removed and a coating according to the
invention, if desired. The semi-permeable membrane material can be
applied to the permeable material to be dried and/or to the coating
according to the invention. The semi-permeable membrane can also
prevent undesired transfer of materials to a coating of the
invention or to the support containing the coating.
A coating according to the invention can be employed more than
once. For instance, a single solid coating comprising a mixture of
a poly(ethylene oxide) having a molecular weight of about 190 to
about 20,000 with poly(ethylene oxide) having an average molecular
weight of 100,000 to 5,000,000, about 1.0 to about 4.0 mils thick
on a paper support can be employed for removing more than 90
percent by weight of the water from at least six pieces of moist
photographic film using a contact time of less than two minutes for
each piece of film.
In general, any diffusible liquid can be removed from a permeable
solid according to the invention which is more strongly attracted
to a drying element of the invention than said permeable solid when
the drying element and permeable solid are intimately contacted.
Suitable diffusible liquids include, for example, water, methanol,
liquid lower alkyl amines, such as ethyl amine, and lower alkanol
amines, such as ethanol amine and propanol amine.
The theory by which diffusible liquids are removed according to the
invention is not understood. However, it is believed that in the
case of a poly(ethylene oxide), the diffusible liquid forms
hydrogen bonds with the poly(ethylene oxide). Hydrogen bonding
between materials is described, for example, in The Hydrogen Bond
by Pimental and McClellan, W. H. Freeman and Company, San
Francisco, 1960.
Various addenda can be present in and/or on the coating and/or a
support, if one is employed, according to the invention, especially
those known to be beneficial in photographic elements, compositions
and processes. The materials from which the diffusible liquid is
removed can also contain such addenda. The types of addenda and
suitable concentrations can be determined by those skilled in the
art. Suitable addenda include, for example, hardeners, such as
those set out in British Pat. No. 974,317; buffers, such as various
sulfonamides and boraxes; coating aids; plasticizers;
speed-increasing addenda; stabilizing agents and the like.
It has also been found that various sugars, e.g. sucrose and
dextrose, can be included in a coating of the invention. The amount
which is suitable can vary depending on the coating components, the
solid material from which liquid is to be removed, and the like.
For example, a composition which can be employed for preparing a
coating for drying a moist photographic element comprises about 1
to about 1,000 grams of sucrose and/or dextrose per liter of
coating composition.
In contacting material from which liquid is to be removed and a
solid coating containing an organic desiccant according to the
invention a wide range of pressure can be emloyed. It is not
necessary, and often undeisrable, to employ high pressure in
contacting the materials according to the invention, e.g. pressures
or more than about 50 kilograms per square centimeter can be
undesired. Any suitable means can be employed for contacting the
materials, e.g. in the case of a photographic element it is
suitable to pass the photographic element and the drying element of
the invention between rollers, or to place the photographic element
on a stationary solid surface and press the drying element onto the
element.
The time required for removal of diffusible liquid from a permeable
solid can vary depending on many factors, such as the materials to
be dried, the amount and type of liquid to be removed, the
components of the coating employed for removing the liquid, and the
like. In general, coatings according to the invention can remove a
diffusible liquid from a permeable solid, such as a layer of a
photographic element, containing the liquid in less than about 120
seconds, e.g. about 1 to about 60 seconds. For instance, a typical
coating according to the invention comprising a mixture of a
poly(ethylene oxide) having a molecular weight of about 6,000 to
7,500 with a high molecular weight, highly crystalline
poly(ethylene oxide) can remove more than 90 percent of the water
in a moist photographic element under ambient conditions, e.g. a
temperature of about 20.degree.C. to about 30.degree.C., in less
than 60 seconds, and usually in a fraction of a second up to 15
seconds. If necessary, however, longer time of contact between the
drying element of the invention and the material from which liquid
is to be removed can be employed.
The temperatures, pressures, and humidities which are suitable for
use according to the invention can vary over wide ranges. Usually
ambient temperature, pressure and humidity are suitable; however,
in some cases it can be desirable to use and/or store the coatings
of the invention under controlled conditions, for example, to avoid
unnecessary premature take-up of moisture from the air when the
coating is to be employed to remove water from a moist photographic
element under conditions of high humidity and/or temperature, e.g.
under tropical conditions.
A drying element of the invention can be stored and/or packaged in
any suitable containger, e.g. in foil and/or plastic wrappers,
which are air and/or moisture tight, before use.
Any support, if one is emloyed, can be used for a coating of the
invention and such a support can be in any suitable shape or form.
These include those commonly employed in the photographic art, such
as films, including cellulose acetate films, polyester films, such
as polyethylene terephthalate films, polyvinyl acetal films,
polystyrene films, polycarbonate films, and related materials,
papers, e.g. paper supports coated with resinous materials, e.g.,
coated with polyethylene, polypropylene, and/or ethylene-butene
copolymers, glass, fabrics, metal and the like. Supports in the
form of webs or tapes can be used, for example. Supports which act
as a reservoir for diffusible liquid removed are especially
suitable. For this reason, absorbent fibrous materials formed from,
for example, textile or glass fibers, paper and/or similar water
absorbent supports can be especially useful.
A drying element and/or process of the invention is useful for
rapidly removing diffusible liquid from a wide variety of
photographic elements containing such liquid. For example, it can
be used for removing water from any suitable photographic element
in a moist condition.
Photographic elements employed in the practice of the invention
contain a layer comprising any of the known water permeable binding
materials suitable for photographic purposes. These includes, for
example, gelatin, cellulose derivatives, polymerized vinyl
compounds, as well as mixtures of such binding agents. These
binding agents can contain water insoluble polymers, such as
polymerized ethylenically unsaturated compounds, e.g. polymers of
acrylates and methacrylates.
The photographic elements which can be dried according to the
invention include, among others, those which contain a photographic
silver salt emulsion, e.g. a silver halide gelatino emulsion layer,
or a non-silver halide emulsion. These can be non-spectrally
sensitized emulsions, such as x-ray type emulsions, or they can be
orthochromatic, panchromatic, infra-red sensitive, and the like
emulsions containing spectral sensitizing dyes, such as described
in U. S. Pat. Nos. 2,526,632 and 2,503,776. Spectral sensitiziers
which can be used include cyanines, merocyanines, styryls and
hemicyacanines.
For example, the invention can be employed for removing diffusible
liquid, such as water, from layers of photographic elements used
for color photography, e.g. it can be used for drying films and/or
prints used in color photography, such as emulsions containing
color-forming couplers or emulsions developed by solutions
containing couplers or other color generating materials; emulsions
of the mixed-packet type, such as described in U. S. Pat. No.
2,698,794 of Godowsky, issued Jan. 9, 1955; or emulsions of the
mixed grain type, such as described in U. S. Pat. Nos. 2,592,243 of
Carroll and Hanson.
The drying element and/or processes of the invention can be used in
processing emulsions intended for use in diffusion transfer
processes which utilize undeveloped silver salts in the non-image
areas of the negative to form a positive by dissolving the
undeveloped silver salts and precipitating them on a receiving
layer in close proximity to the original silver salt emulsion
layer. Such processes are desribed, for example, in U.S. Pat. No.
3,020,155 of Yackel et al., issued Feb. 6, 1962; U. S. Pat. Nos.
2,584,029, issued Jan. 29, 1952; 2,698,236, issued Dec. 28, 1954;
and 2,543,181, issued Feb. 27, 1951, of E. H. Land and U. S. Pat.
No. 2,352,014 of Rott, issued June 20, 1944. The invention can also
be used in color transfer processes which utilize the diffusion
transfer of developer, coupler or dye, from a light sensitive layer
to a second layer, such as described in U. S. Pat. No. 2,559,643 of
Land, issued July 10, 1951; U.S. Pat. No. 2,698,798, issued Jan. 4,
1955; U. S. Pat. No. 2,756,142 of Yutzy, issued July 24, 1956; U.S.
Pat. No. 3,252,915 of Weyerts et al., issued May 31, 1966; and U.S.
Pat. No. 3,227,550 of Whitman et al, issued Jan. 4, 1966.
The invention can be used in processing emulsions used in
lithography, preparation of direct prints, or in colloid transfer
processes as well as in processing of elements using monobath
processes, such as described in U.S. Pat. No. 2,875,048 of Haist et
al, issued Feb. 24, 1959, and web-type processing such as described
in U. S. Pat. No. 3,179,517 of Tregillus et al. It can also be used
in so-called stabilization processing, such as processing an
element containing an incorporated developer through an activator
bath containing a thiocyanate stabilizer, as described, for
example, in British Pat. No. 1,061,892, issued Mar. 15, 1967, or in
an article titled "Stabilization Processing of Films and Papers" by
H. D. Russell, E. C. Yackel and J. S. Bruce, P.S.A. Journal,
August, 1950, pages 59-62.
The drying elements and/or processes of the invention can be
employed in the production of layers of liquid permeable solid
materials. For instance, the flexible, liquid permeable, drying
elements and processes of the invention can be employed in the
production of layers of unexposed photographic elements whih
require removal of water and/or other suitable liquid at some
stage. A typical process according to the invention for the
production of a layer of a photographic element accordingly
comprises applying a hydrophilic colloid coating to a substrate,
the resulting coating containing water and/or other suitable
liquid, and subsequently contacting the hydrophilic colloid coating
with a flexible, liquid permeable, drying element comprising an
organic desiccant, to remove a substantial portion of the water
and/or other suitable liquid from the hydrophilic colloid
coating.
A wide range of coating methods and conditions can be employed for
preparing the coatings from which liquids, e.g. water, can be
removed according to the invention. In general, coating methods,
compositions, and conditions commonly employed in the photographic
art can be employed.
A typical method for production of a raw photographic emulsion
layer comprises applying a coating of a photographic emulsion to a
substrate, setting the resulting coating, such as by chilling or
fuming with ammonia in the case of gelatino emulsion coatings, and
contacting the resulting coating with a flexible, liquid permeable,
drying element comprising an organic desiccant. For instance, a
raw, wet, photographic emulsion coating can be contacted with a
solid, flexible, coating comprising an organic desiccant, such as
contacted with a supported or unsupported coating containing a
poly(ethylene oxide) and/or one of the organic desiccants
described, to remove a substantial portion of the water from the
raw photographic emulsion coating.
The raw photographic emulsion coating can be contacted using
essentially the same conditions and time of contact as employed for
contacting exposed and processed, wet photographic elements to
effect removal of water.
One of the useful characteristics of a coating of the invention is
that in removing diffusible liquid from a permeable solid, certain
solid materials dissolved in the diffusible liquid are also
substantially removed from the permeable solid. For example,
certain compounds in a photographic element containing a diffusible
liquid can be removed from the element with the diffusible liquid
according to the invention. These compounds in the case of a
photographic element processed with one or more aqueous processing
solutions, e.g. a monobath, a stabilizer bath or a bath causing
some of the compounds in the element to become water soluble, such
as silver halide solvents, are usually water soluble. When the
moist element containing such compounds is contacted with a drying
element according to the invention these compounds are removed from
the element with the water removed. For instance, in processing a
photographic element using web processing techniques as set out,
for example, in U. S. Pat. No. 3,179,517 of Iregillus et al.,
certain processing agents are present in the moist processed
element. A significant amount of these processing agents and other
water soluble compounds formed in processing, such as a water
soluble complex formed between unexposed silver halide and a silver
halide solvent, are removed from the element when a coating
according to the invention is contacted with the moist processed
element. The concentrations and types of compounds removed from the
moist photographic element can vary over a wide range and will
depend on many factors such as the type of element, the type of
processing carried out, the coating according to the invention
employed, and the like.
A wide variety of coating compositions and means for applying them
can be employed for preparing the coatings of the invention. In
general, any composition, coating means or coating process which
provides an adherent coating, having the desired thickness, the
desired amounts of components, and the desired liquid removal
properties can be employed. It is often advantageous to employ an
organic solvent in the coating composition. Any organic solvent is
suitable which provides the desired coating and can be selected by
those skilled in the coating art. Aqueous solvents have been found
especially useful, such as mixtures of water and a water miscible
alcohol, e.g. methanol or acetonitrile.
An especially suitable coating composition comprises a mixture
of
a. about 70 percent to about 90 percent by weight of the total
composition solvent, comprising about 10 percent to about 20
percent by volume water and about 70 percent to about 90 perent by
volume water miscible organic solvent, e.g. water miscible alcohol
such as methanol, and
b. about 10 percent to about 20 percent by weight of the total
composition solids soluble in the said solvent comprising about 50
to 100 percent by weight water soluble, high molecular weight,
highly crystalline poly(alkylene oxide), e.g. poly(ethylene oxide),
and 0 to 50 percent by weight poly(alkylene oxide) having a
molecular weight of about 190 to about 20,000, e.g. poly (ethylene
oxide). For example, a coating composition within the scope of this
embodiment comprises a mixture of:
1. about 85 percent by weight solvent comprising about 15 percent
by volume water and about 85% by volume methanol, and
2. about 15 percent by weight solids, comprising about 10 percent
by weight poly(ethylene oxide) having an average molecular weight
of about 6,000 to 7,500 and a high molecular weight, highly
crystalline poly(ethylene oxide). Such compositions are typically
viscous mixtures.
Another embodiment of the invention is in a process for removing a
diffusible liquid from a permeable solid containing said liquid by
contacting said permeable solid with a solid material which removes
said liquid from said permeable solid, the improvement comprising
contacting said permeable solid with a flexible, liquid permeable,
drying element comprising a solid coating containing an organic
desiccant.
According to the invention, any method of and/or means for
contacting the permeable solid containing the diffusible liquid and
the solid coating of the invention can be used which provides the
desired removal of liquid from the permeable solid. A coating of
the invention can, for example, be on a flat, vertical, horizontal,
or angular surface, on a continuous web, or it can be on a drum or
cylinder, such as one which rotates, which contacts the permeable
solid, e.g. a moist photographic element. It is important, however,
that the method and means employed provide intimate contact. One
method which is suitable comprises wrapping a flexible support,
e.g. a paper web, coated on one or both sides with a coating
according to the invention, on a common core with a moist
photographic element, e.g. a roll of moist photographic film.
The amount of solid coating per square foot suitable according to
the invention can vary over wide ranges depending on the components
of the coating, the material to be dried and the like. A coating
consisting of, for example, about 3 grams to about 30 grams,
typically about 4 to about 10 grams per square foot, in and/or on a
suport, if one is used, can be suitable for removing moisture from
a moist photographic element.
A typical process within this embodiment comprises removing
moisture from a moist photographic element by contacting said
element with a solid coating comprising a mixture of a
poly(ethylene oxide) having an average molecular weight of about
190 to about 20,000 and a high molecular weight poly(ethylene
oxide), e.g. a poly(ethylene oxide) having an average molecular
weight of about 100,000 to about 5,000,000. In such a process at
least about 60 percent by weight, and typically at least about 85
percent by weight, of water is removed from said element in about 1
to about 60 seconds at about 20.degree. C.
For example, moisture can be removed from a moist photographic
element by contacting said element for up to about 60 seconds under
ambient conditions of temperature, pressure and humidity with a
drying element which is a paper or film support having a solid
coating comprising a mixture of poly(alkylene oxide) having an
average molecular weight of about 190 to about 20,000 with a high
molecular weight poly(alkylene oxide) about 0.01 millimeter to
about 1.0 millimeters thick to remove at least about 90 percent by
weight of said moisture from said element.
The drying element and processes of the invention are especially
useful in a method of processing an exposed photographic element
comprising contacting said element with a matrix such as a liquid
permeable film or sheet of paper, containing a monobath, such as
described in The Monobath Manual by Grant M. Haist, 1966, to
produce the desired image and drying the resulting moist element by
contacting said element with a solid coating comprising about 10
percent by weight poly(ethylene oxide) and about 90 percent by
weight polymeric binder, for instance, by contacting said element
with a solid coating comprising about 10 percent by weight poly
(ethylene oxide) having an average molecular weight of about 6,000
to about 7,500 with about 90 percent by weight of high molecular
weight poly(ethylene oxide).
The invention is further illustrated in the following examples.
Unless otherwise indicated, percentages employed herein are by
weight.
EXAMPLE 1
This example illustrates removing moisture from a processed, moist
photographic film according to the invention.
A piece of photographic film containing a medium grain silver
bromoiodide gelatino emulsion layer on a polyethylene terephthalate
support is exposed imagewise to light. The film is 35 mm. wide and
25.4 centimeters long. The exposed film is processed using
conventional silver halide developer and stabilizer baths, i.e.
Kodak D-85 developer and Kodak F-5 Fixer. It is then washed for
several minutes in water after which water on the surface of the
film is removed by wiping.
A so-called drying tape, i.e. a paper support containing a coating
according to the invention, is placed in intimate contact with the
moist film under room conditions, i.e. about 21.degree.C. and about
50 percent relative humidity, for 15 seconds by pressing the drying
tape on the emulsion side of the film.
The drying tape in this example is a paper support about 0.1
millimeter thick having a 0.114 millimeter solid coating of a
mixture of 10 percent by weight poly(ethylene oxide) having an
average molecular weight of about 6,000 to 7,500 (Carbowax 6,000,
produced by Union Carbide Corporation, New York, New York) with 90
percent by weight poly(ethylene oxide) having an average molecular
weight of about 600,000 (Polyox WSR-N-3000, produced by Union
Carbide Corporation, New York, New York). The coating is prepared
by coating a composition consisting of a viscous aqueous methanol
solution of the poly(ethylene oxide) compounds on the paper support
with a doctor blade.
At least 90 percent of the moisture is removed from the moist film
and no poly(ethylene oxide) residue is observable on the film
employing this procedure and coating according to the
invention.
EXAMPLE 2
This example illustrates removing moisture from a photographic film
according to the invention which is processed using web processing
according to U. S. Pat. No. 3,179,517 of Tregillus et al, issued
Apr. 20, 1965.
A processing web is prepared by soaking a hydrolyzed cellulose
acetate film support in a 0.1 percent gold chloride solution for 3
minutes and then in a 0.2 percent solution of
N-methyl-p-amino-phenol sulfate. It is washed 5 minutes in water
and then soaked for minutes in a solution comprising:
1-phenyl-3-pyrazolidone 1.0 gram hydroquinone 10.0 grams
2-dimethylaminoethanol-SO.sub.2 addition product (20 mol percent
SO.sub.2) 174.0 grams sodium thiosulfate peutahydrate 2.0 grams
water to make 1 liter
The excess liquid on the surface of the resulting processing web is
removed with a squeegee.
A so-called drying tape is prepared as set out in Example 1.
A piece of photographic film having a medium grain siver
bromoiodide gelatino emulsion having a total thickness in dry
condition of 108 microns is exposed imagewise to light. It is then
rolled in contact with the described processing web for a few
minutes until full development of the exposed film occurs. The film
and processing web are then peeled apart.
The resulting moist film having a total thickness of 130 microns is
then contacted with the described drying tape for 15 seconds. This
produces a film which is substantially dry and has no poly(ethylene
oxide) residue observable on the film.
EXAMPLE 3
This example illustrates drying of a photographic film using a
coating and process of the invention.
A photographic film containing a medium grain silver bromoiodide
gelatino emulsion layer, prehardened during manufacture, is exposed
imagewise to light. It is then processed in processing solutions
and apparatus as described in U. S. Pat. No. 3,179,517 -- Tregillus
et al., issued Apr. 20, 1965. The film is washed in water at about
20.degree.C. for a period of 2 minutes. It is removed from the
water, each surface wiped to remove surface moisture, and placed on
a clean, dry, smooth, polished metal surface.
A drying tape is prepared as described in Example 1, containing a
coating 0.114 millimeter thick consisting of 50 percent by weight
poly(ethylene oxide) having an average molecular weight of about
1,300 to about 1,600 (Carbowax 1540, produced by Union Carbide
Corporation, New York, New York) and 50 percent by weight highly
crystalline poly(ethylene oxide) having an average molecular weight
of about 600,000 (Polyox WSR-N-3000) is pressed onto the moist
film.
Within 15 seconds at least 95 percent of the moisture in the film
is removed. No observable poly(ethylene oxide) residue is left on
the film after the drying tape is removed from the film.
EXAMPLE 4
The procedure set out in Example 3 is repeated with the exception
of using a coating 0.127 millimeter thick consisting of 100 percent
high molecular weight poly(ethylene oxide) (Polyox WSR-N-4000,
produced by Union Carbide Corporation, New York, New York) having a
melting point of about 65.degree.C. on the paper support.
Substantially the same results are obtained as in Example 3.
EXAMPLE 5
The procedure set out in Example 3 is repeated with the exception
of using a coating 0.152 millimeters thick consisting of 50 percent
by weight poly(ethylene oxide) having an average molecular weight
of 6,000 to 7,500 (Carbowax 6000) and 50 percent by weight poly
(ethylene oxide) having an average molecular weight of about
600,000 (Polyox WSR-N-3000) on the paper support.
Substantially the same results are obtained as in Example 3.
EXAMPLE 6
The procedure set out in Example 3 is repeated with the exception
of using a coating 0.152 millimeter thick consisting of 50 percent
by weight poly(ethylene oxide) having an average molecular weight
of 380 to 420 (Carbowax 400, produced by Union Carbide Corporation,
New York, New York) and 50 percent by weight poly(ethylene oxide)
having an average molecular weight of about 600,000 (Polyox
WSR-N-3000) on the paper support.
Substantially the same results are obtained as in Example 3.
EXAMPLE 7
The procedure set out in Example 3 is repeated with the exception
of using a coating 0.152 millimeter thick consisting of 50 percent
by weight poly(ethylene oxide) having an average molecular weight
of 570 to 630 (Carbowax 600, produced by Union Carbide Corporation,
New York, New York) and 50 percent by weight poly(ethylene oxide)
having an average molecular weight of about 600,000 (Polyox
WSR-N-3000) on the paper support.
Substantially the same results are obtained as in Example 3.
EXAMPLE 8
The procedure set out in Example 3 is repeated with the exception
of using a coating 0.114 millimeter thick consisting of 100% by
weight highly crystalline poly(ethylene oxide) having an average
molecular weight of about 600,000 (Polyox WSR-N-3000) on the paper
support.
Substantially the same results are obtained as in Example 3.
EXAMPLE 9
The procedure set out in Example 3 is repeated with the exception
of using a coating 0.140 millimeter thick consisting of 25% by
weight poly(ethylene oxide) having an average molecular weight of
570 to 630 (Carbowax 600) and 75 percent by weight high molecular
weight, highly crystalline poly(ethylene oxide) (Polyox WSR-N-3000)
on the paper support.
Within 5 seconds at least 90 percent of the moisture in the film is
removed. No observable residue is left on the film.
EXAMPLE 10
This example illustrates the use of sugars, such as sucrose, in the
practice of the invention.
The procedure set out in Example 3 is repeated with the exception
of using a coating 0.203 millimeter thick consisting of 50 percent
by weight ordinary table sugar, i.e. sucrose, and 50 percent by
weight high molecular weight, highly crystalline poly(ethylene
oxide) (Polyox WSR-N-3000) on the paper support.
Within 5 seconds at least 90 percent of the moisture in the film is
removed.
EXAMPLE 11
This example illustrates the use of sugars in the practice of the
invention.
The procedure set out in Example 3 is repeated using a coating
0.229 millimeter thick consisting of 10 percent by weight poly
(ethylene oxide) having an average molecular weight of about 6,000
to 7,500 (Carbowax 6000), 45 percent by weight high molecular
weight highly crystalline poly(ethylene oxide) (Polyox WSR-750,
produced by Union Carbide Corporation, New York, New York) and 45
percent by weight ordinary table sugar, i.e. sucrose, on the paper
support.
About 90 percent of the moisture in the film is removed within
about 5 seconds.
EXAMPLE 12
The procedure set out in Example 3 is repeated using a coating
0.127 millimeter thick consisting of 6 percent by weight poly
(ethylene oxide) having an average molecular weight of 6,000 to
7,500 with 94 percent by weight poly(ethylene oxide) having an
average molecular weight of about 300,000 (Polyox WSR-N-750) on the
paper support.
Substantially the same results are obtained as in Example 3.
EXAMPLE 13
The procedure set out in Example 3 is repeated using a coating
0.107 millimeter thick consisting of 100 percent by weight poly
(ethylene oxide) having an average molecular weight of about
4,000,000 (Polyox WSR-301, produced by Union Carbide Corporation,
New York, New York) on the paper support.
At least 90 percent of the moisture in the film is removed within
30 seconds.
EXAMPLE 14
The procedure set out in Example 3 is repeated using a coating
0.127 millimeter thick consisting of 10 percent by weight poly
(ethylene oxide) having an average molecular weight of about 6,000
to 7,500 (Carbowax 6000) and 90 percent by weight poly(ethylene
oxide) having an average molecular weight of about 200,000 (Polyox
WSR-35, produced by Union Carbide Corporation, New York, New York)
on the paper support.
At least 90 percent of the moisture in the film is removed within 5
seconds.
EXAMPLE 15
The procedure set out in Example 3 is repeated using a coating
0.178 millimeters thick consisting of 100 percent poly(ethylene
oxide) having an average molecular weight of about 200,000 (Polyox
WSR-35) on the paper support.
At least 90 percent of the moisture in the film is removed within 5
seconds.
EXAMPLE 16
This example illustrates the use of an inorganic desiccant in a
coating according to the invention.
The procedure set out in Example 3 is repeated with the exception
of using a coating consisting of 10 percent by weight poly
(ethylene oxide) having an average molecular weight of about 6,000
to 7,500 (Carbowax 6000), 85 percent by weight poly(ethylene oxide)
having a molecular weight of about 600,000 (Polyox WSR-N-3000 ) and
5 percent by weight crystalline alumino silicate molecular sieve
material on the paper support.
At least 90 percent of the moisture in the film is removed within 5
seconds. Also, increased moisture capacity as well as decreased
adhesion between the film and drying tape are observed in
comparison to coatings not containing the molecular sieve
material.
EXAMPLE 17
This example illustrates the use of a semi-permeable membrane
between a material from which diffusible liquid is to be removed
and a polymeric coating in the practice of the invention.
The procedure set out in Example 3 is repeated with the exception
that a strip of moisture permeable cellophane about 30 centimeters
long, about 8.25 centimeters wide and about 0.1 mm. thick is soaked
in water and, after removing surface moisture, applied between the
moist film and drying tape before the drying tape and moist film
are pressed together. Also, a coating consisting of 56 percent by
weight poly(ethylene oxide) having a molecular weight of about
1,300 to about 1,600 (Carbowax 1,540) and 18 percent by weight
poly(ethylene oxide) having a molecular weight of 600,000 (Polyox
WSR-N-3000) is used on the paper support. Some of this mixture is
absorbed into the paper support. The polymer content in and on the
paper support is 4.9 grams per square foot.
About 84 percent of the moisture is removed from the film within 60
seconds.
EXAMPLE 18
This example illustrates the use of a semi-permeable membrane in
the practice of the invention.
A drying tape is impregnated with a highly crystalline
poly(ethylene oxide) having a molecular weight of about 600,000
(Polyox WSR-N-3000) by soaking a paper support in an aqueous
solution consisting of 2 grams of the poly(ethylene oxide) per
liter of water. The resulting support is allowed to dry under room
conditions producing a paper support containing 18.7 grams of the
poly(ethylene oxide) per square foot. Use of this drying tape as
set out in Example 3 with a semi-permeable layer of cellophane
between the moist film and drying tape as set out in Example 17
removes at least 90 percent of the moisture from the film within 60
seconds.
EXAMPLE 19
The procedure set out in Example 18 is repeated with the exception
that an overcoat consisting of a mixture of 70 percent by weight
poly(ethylene oxide) having a molecular weight of 570 to 630
(Carbowax 600, produced by Union Carbide Corporation, New York, New
York) is applied to the drying tape to produce a total
poly(ethylene oxide) content in and on the drying tape of 27.0
grams per square foot.
substantially the same results are obtained as in Example 18. In
this example, without the cellophane between the drying tape and
the moist film, a noticeable residue remains on the film after
removal of moisture.
EXAMPLE 20
This is a comparative example comparing use of a polymeric coating
of the invention for drying a gelatino emulsion in production of a
photographic film to air drying an identical emulsion.
A high contrast photographic silver chlorobromide gelatino emulsion
is coated on a polyethylene terephthalate support at the rate of
351 milligrams of silver per square foot and 347 milligrams of
gelatin per square foot. The emulsion is chill set and divided into
two equal parts, (A) and (B).
Part (A) is contacted with a drying tape consisting of a paper
support containing about 7.5 grams per square foot of a mixture of
10 percent by weight poly(ethylene oxide) having a molecular weight
of about 6,000 to 7,500 (Carbowax 6000) and 90 percent by weight
poly(ethylene oxide) having a molecular weight of about 600,000
(Polyox WSR-N-3000) in and/or on the support. The coating on the
support is about 0.004 millimeter thick. After 15 seconds, the
drying tape is removed. The gelatino emulsion is dry to the
touch.
Part (B) is air dried using forced air drying at about room
temperature. The time required to dry the film is about 5
minutes.
After drying, both (A) and (B) are exposed 5 seconds to a standard
step wedge, developed in Kodak D-85 Developer, fixed in Kodak F-5
Fixer, washed in water, and air dried. Part (A) has a 0.52 log E
speed loss compared to Part (B) and the surface appears slightly
reticulated.
EXAMPLE 21
A solution of 10 percent by weight highly crystalline poly
(ethylene oxide) having a molecular weight of about 600,000 (Polyox
WSR-N-3000) in acetonitrile is coated on a paper support at the
rate of 6.0 grams per square foot and allowed to dry at room
temperature. Some of the poly(ethylene oxide) is absorbed into the
paper. An aqueous 6 percent by weight gelatin solution is coated on
a polyethylene terephthalate support at the rate of 498 milligrams
of gelatin per square foot. The resulting coating is contacted for
15 seconds with a drying tape as described in Example 20. After
removing the drying tape, the gelatin coating is dry.
EXAMPLE 22
A multilayer photographic film containing gelatino silver halide
emulsion, red, green and blue sensitive layers (Kodak Ektachrome-X
film) is soaked in water for several minutes until the emulsion
layers are swollen, i.e. from a total support and emulsion
thickness in a dry condition of 152 microns to a total thickness of
242 microns. The surface moisture is removed by wiping. The
resulting moist film is contacted with a drying tape consisting of
a paper support having a coating 0.064 millimeters thick consisting
of 7.5 grams per square foot of a mixture of 10 percent by weight
poly(ethylene oxide) having a molecular weight of about 6,000 to
7,500 (Carbowax 6000) and 90 percent by weight poly (ethylene
oxide) having a molecular weight of about 600,000 (Polyox
WSR-N-3000). Within 60 seconds, at least 90 percent of the moisture
is removed from the moist film, i.e. the total thickness of the
support and emulsion layer is 157 microns. No noticeable residue
remains on the film.
EXAMPLE 23
The procedure set out in Example 22 is repeated with the exception
that a coating 0.051 millimeter thick consisting of 10 percent by
weight poly(ethylene oxide) having an average molecular weight of
6,000 to 7,500 (Carbowax 6000) and 90 percent by weight of a
copolymer of acrylamide with 2-acetoacetoxyethyl methacrylate
containing 90 percent by weight acrylamide is on the paper support.
Substantially the same results are obtained as in Example 22.
EXAMPLE 24
Several lines of blue ink are placed with a conventional ink pen on
a piece of conventional writing paper. A drying tape as described
in Example 22 is contacted with the paper by pressing the drying
tape over the portion of the paper containing the ink lines while
the ink is still moist. The drying tape effects drying of the ink
within less than 5 seconds without leaving noticeable residue on
the writing paper or distorting the lines.
EXAMPLE 25
This example illustrates use of a multilayer polymeric coating in
the practice of the invention.
The procedure set out in Example 3 is repeated with the exception
that an initial coating consisting of 10 percent by weight
poly(ethylene oxide) having a molecular weight of about 6,000 to
7,500 (Carbowax 6000), 75 percent by weight poly(ethylene oxide)
having a molecular weight of about 600,000 (Polyox WSR-N-3000) and
15 percent by weight crystalline alumino silicate molecular sieve
material is applied to the paper support and allowed to dry
followed by application of an overcoat, about the same thickness as
the initial coating, consisting of 10 percent by weight
poly(ethylene oxide) having a molecular weight of about 6,000 to
7,500 (Carbowax 6000) and 90 percent by weight poly(ethylene oxide)
having a molecular weight of about 600,000 (Polyox WSR-N-3000).
At least 90 percent of the moisture in the moist film is removed
within 15 seconds.
The invention has been described in detail with particular
reference to preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention as described hereinabove and
as defined in the appended claims.
* * * * *