U.S. patent number 3,620,728 [Application Number 04/883,358] was granted by the patent office on 1971-11-16 for receiving sheet for diffusion transfer processes.
This patent grant is currently assigned to Eastman Kodak Company, Rochester, NY. Invention is credited to David Alan Cottingham.
United States Patent |
3,620,728 |
|
November 16, 1971 |
RECEIVING SHEET FOR DIFFUSION TRANSFER PROCESSES
Abstract
A receiving sheet for diffusion transfer processes wherein the
image-receiving layer contains as the binding agent a mixture of an
alkali metal salt of carboxymethyl cellulose and a propylene glycol
ether-substituted methyl ether of cellulose and a process for using
the receiving sheet. The novel mixture of binders provides an
improved positive which effects more rapid image-transfer, better
tone and combines ease of sandwich separation with immediate dry
feel. 10 Claims, No Drawings
Inventors: |
David Alan Cottingham
(Northwood, GB2) |
Assignee: |
Eastman Kodak Company, Rochester,
NY (N/A)
|
Family
ID: |
10098137 |
Appl.
No.: |
04/883,358 |
Filed: |
December 8, 1969 |
Foreign Application Priority Data
|
|
|
|
|
Apr 3, 1969 [GB3] |
|
|
17,609/69 |
|
Current U.S.
Class: |
430/232; 430/247;
430/231 |
Current CPC
Class: |
G03C
8/56 (20130101) |
Current International
Class: |
G03C
8/00 (20060101); G03C 8/56 (20060101); G03c
005/54 () |
Field of
Search: |
;96/29,114.3,113 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Norman G. Torchin
Assistant Examiner: John L. Goodrow
Attorney, Agent or Firm: W. H. J. Kline B. D. Wiese H. E.
Byers
Claims
1. A diffusion transfer receiving sheet comprised of a support, an
image-receiving layer on said support, said image-receiving layer
being comprised of a colloid binding agent composition comprised of
about 20 to about 50 percent by weight of an alkali metal salt of
carboxymethyl cellulose and about 80 to about 50 percent by weight
of a propylene glycol ether-substituted methyl ether of cellulose
containing about 28 to 30 percent methoxyl groups and about 7 to 12
percent propylene glycol ether
2. The receiving sheet of claim 1 wherein the image-receiving
layer
3. The receiving sheet of claim 2 wherein the silver precipitating
agent is
4. The receiving sheet of claim 3 wherein the heavy metal sulfide
is nickel
5. The receiving sheet of claim 1 wherein the alkali metal salt
of
6. The receiving sheet of claim 1 wherein said image-receiving
layer
Description
This invention relates to an improved reception sheet for the
direct production of positive photographic images by silver and
color diffusion transfer process and a method of using the
reception sheet.
In the silver salt diffusion transfer process a positive image is
transferred by chemical means from an exposed silver halide layer
carried by a binding medium such as gelatin to an image-receiving
layer comprised of a binding medium usually carrying a
silver-precipitating agent. Both the silver halide layer and
image-receiving layer are usually supported and are commonly
referred to in the diffusion transfer art as the negative sheet and
positive sheet, respectively. Transfer of the image is effected by
bringing the silver halide layer into contact with the reception
layer while both layers are moistened with a processing solution
which develops the exposed silver halide and at the same time
dissolves the nonexposed silver halide. The dissolved silver halide
diffuses the reception layer where it is reduced to a positive
image under the activity of the precipitating agent present in the
reception layer.
In color diffusion transfer processes, a photosensitive element
including a silver halide emulsion layer is exposed to create
therein a latent image which is developed and concurrent with and
under the control of this development an imagewise distribution of
mobile color-providing substances is formed. At least a portion of
these color-providing substances is transferred through the
processing solution to the image-receiving layer to form a colored
image thereon.
The photosensitive and reception layers contacted in these transfer
processes must be left together for a short period of time to
complete transfer of the image-forming components through the
processing solution to the reception layer. It has been found that
contact of the two layers for too great a time period frequently
presents separation difficulties.
Attempts have been made to alleviate this difficulty as, for
instance, by the process described in British Pat. No. 687,751
wherein an improvement in separation is obtained by using in the
layers brought together a nongelatin binding agent in one of the
layers and a gelatin binding agent in the other layer. Other ways
of facilitating separation of the sheets is by the use of silica in
or on the reception layer and by use of cellulose ethers as the
binding agents as disclosed, for instance, in British Pat. No.
703,312. Unfortunately, certain cellulose ethers such as sodium
carboxymethyl cellulose, when used as the sole binder in the layers
do not produce a stable receiving layer. Consequently, when these
materials are employed, they are usually used in admixture with
another binder such as gelatin. Even with this combination,
however, separation of the layers becomes difficult at times in
excess of approximately 1 minute after sandwiching. More often than
not, substitution of binding agents known for their easy release,
although performing this function satisfactorily, adversely effect
other desirable properties of the reception layer.
It is an object of the present invention, therefore, to provide a
diffusion transfer receiving sheet improved in the length of time
in which it can be readily separated from a silver-halide
containing layer with which it is sandwiched.
Another object of the invention is to provide a reception sheet
which when separated from a negative sheet with which it has been
sandwiched exhibits excellent dry feel when separated and which may
be written on with a ballpoint pen immediately after sandwich
separation.
A further object is to provide an economical receiving sheet which
can be readily separated after 1 minute of sandwich of the positive
and negative sheets and a process of using the receiving sheet.
Another object of the invention is to provide a receiving sheet
which when used in conjunction with a negative yields a more rapid
image-transfer, better tone and combines ease of sandwich
separation with immediate dry feel.
These and other objects of the invention are obtained by a
diffusion transfer receiving sheet comprised of a support, and
image-receiving layer on said support, the image-receiving layer
being comprised of a colloid binding agent composition comprising
about 20 to 50 percent by weight of an alkali metal salt of
carboxymethyl cellulose and 50 to 80 percent by weight of a
propylene glycol ether-substituted methyl ether of cellulose
containing about 28 to 30 percent of methoxyl groups and about 7 to
12 percent of propylene glycol ether substitution by weight. The
percentages of the cellulose ether components in the binding agent
composition are on a solids basis while the percentages of the
methoxy and propylene glycol ether-substituted groups are based on
the weight of the substituted methyl ether of cellulose.
DETAILED DESCRIPTION OF THE INVENTION
The alkali metal carboxymethyl cellulose component of the mixed
colloid binder of the invention is a water-soluble material which
may be prepared, for instance, by the procedure described in U.S.
Pat. Nos. 2,618,609; 2,607,772 or 2,667,480. The preferred alkali
metal carboxymethyl cellulose is sodium carboxymethyl cellulose but
other alkali metal derivatives such as potassium, lithium and the
like may be used.
The propylene glycol ether-substituted methyl ether of cellulose
which constitutes the second essential ingredient of the mixed
colloid binding agent of the invention likewise may be prepared by
a variety of methods known to the art. It is commercially available
as Methocel 60 H.G.
Precipitating agents are preferably included in the image-receiving
layer of the receiving sheet used in silver halide diffusion
transfer processes. Suitable precipitating agents include metallic
sulfides and selenides, these terms being understood to include the
selenosulfides, the polysulfides and the polyselenides. The
preferred precipitating agents are the heavy metal sulfides, e.g.,
of zinc, chromium, gallium, iron, cadmium, cobalt, nickel, lead,
antimony, bismuth, silver, cerium, arsenic, copper; and the heavy
metal selenides, e.g., of lead, zinc, antimony, and nickel. Also
suitable as precipitating agents are heavy metals such as silver,
gold, platinum, palladium and mercury. The silver precipitating
agents are provided in the receiving layer in a highly dispersed
condition, preferably as colloidal particles. The silver
precipitating agent is employed in the receiving sheet in small
concentrations. Concentrations of about 2 .+-. 10.sup..sup.-5
gram-moles for each square foot of the surface area of the
receiving sheet have proved adequate.
Advantageously, particles of silica, preferably in colloidal form,
are also present in the image-receiving layer along with the
precipitating agent. Although the essentially pure forms of silica
such as silica aerogel give best results, it is possible to use
particles of less pure silicas such as, for instance, silicas
derived from kieselguhr, diatomaceous earth, infusorial earth, etc.
The amount of silica employed is generally substantially greater
than the silver precipitating agent used.
If desired, other ingredients commonly provided in the
image-receiving layers such as antifoaming agents, coatability
improvers, etc. may be added as is well known in the art. Also, in
addition to the alkali metal carboxymethyl cellulose and the
propylene glycol ether-substituted methyl ether of cellulose
components, there may be included in the binding agent composition
other known binding agents of the art, as long as they are used in
concentrations that do not have a deleterious effect upon the
advantageous results obtained by the novel colloid binding agent
mixture of the invention. Illustrative of such binding agents are
polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose,
partially hydrolyzed polyvinyl acetate, polyvinyl pyrrolidone and
the like.
The image-receiving layer of the invention containing the novel
binder composition can be prepared and applied to suitable supports
by any of the known procedures and techniques of the art. A
particularly desirable method involves preparing an aqueous
dispersion of the silica particles to which there is added
effective quantity of one or more of a suitable sulfide
ion-capturing salt such as a nitrate, borate, chloride, sulfate,
acetate, etc., of any of the following metals: nickel, lead, iron
cobalt, and the like. Thereafter, an equimolar quantity of a
soluble sulfide is added. The anions of sulfide and the cations of
the ion-capturing salt combine to precipitate from the solution as
insoluble crystals of the metal sulfide thereby producing a
dispersion of the insoluble sulfide in the silica. The mixed
colloid binding agent of the invention in water is then added to
the silica-metal sulfide dispersion and the resulting mixture then
coated on a suitable sheet support by any of the conventional
methods of the art.
Supports upon which the image-receiving layer may be disposed
include by way of example, paper, cellulose nitrate film, cellulose
acetate film, polyvinyl acetal film, polystyrene film,
polyethyleneterephthalate film, polyethylene film, polypropylene
film, polyethylene-coated paper, polypropylene-coated paper, and
the like.
The silver halide layer utilized in conjunction with novel
receiving sheets of the invention can be any of the conventional
negative-type developing emulsions. Typical silver halides include
silver chloride, silver bromide, silver bromoiodide, silver
chloroiodide, silver chlorobromoiodide, and the like. Mixtures of
more than one of such silver halides can be utilized. In accordance
with the usual practice, such silver halide emulsions can contain,
for instance, spectral sensitizers, speed-increasing addenda,
hardeners, coating aids, plasticizers, antifoggants, and similar
conventional emulsion addenda. Developing agents may be
incorporated into the silver halide emulsion, if desired, or can be
contained in a contiguous layer. The silver halide layers may be
coated on a variety of supports of the type described above for the
image-receiving sheets.
Typically, the photographic processing liquid layer in the silver
salt diffusion transfer systems, through which the image-forming
component is transferred, is a viscous, aqueous alkaline solution
of a silver halide developer, a silver halide solvent for reaction
with the unexposed portions of a photosensitive layer and, if
desired, a thickening agent.
Suitable silver halide developing agents include hydroquinone,
substituted-hydroquinones, etc., such as those substituted in the
2, 3, 5 or 6 position carbon atoms or any combinations of these
with lower alkyl groups such as methyl, ethyl, propyl, butyl, etc.,
lower alkoxy groups, halogen groups such as chlorine, bromine,
fluorine and other groups commonly used as substituents;
resorcinol, catechol, ascorbic and isoascorbic acid, preferably in
the form of its alkaline metal salt; the 3-pyrazolidones such as
are described in U.S. Pat. No. 2,875,048 Haist et al.; the
aminophenols such as p-aminophenol, N-methylaminophenol, etc.;
developing agents containing an amino group usually in the form of
the hydrochloride or the sulfate, and the like.
Illustrative of typical silver halide solvents are the
water-soluble thiosulfates such as sodium, potassium, and ammonium
thiosulfates; the alkali thiocyanates, alkyl selenocyanates,
thioglycerol, aminoethanediols, p,p'-di-thia-suberic acid, etc. The
preferred silver halide solvents are the thiosulfates. Other
addenda commonly employed in alkaline processing compositions for
diffusion transfer processes may be included in the processing
liquid, if desired. The addenda include, for instance, restrainers
such as potassium bromide, stain preventives such as alkaline metal
sulfites, sequestering agents such as ethylenediaminetetraacetic
acid, 1,3-diamino- 2 -propanoltetraacetic acid, etc.
Thickening agents commonly employed in the processing compositions
include, for instance, hydroxyethyl cellulose or carboxymethyl
cellulose. Thickened processing compositions usually have a
viscosity of at least 5,000 c.p.s. to 100,000 or even 200,00
c.p.s.
As examples of color diffusion transfer processes may be mentioned
the processes disclosed in U.S. Pat. No. 2,983,606 wherein dye
developers (i.e., compounds which contain in the same molecule both
the chromophoric system of a dye and also a silver halide
developing function) are the color-providing substances, the
processes disclosed in U.S. Pat. No. 2,674,049 wherein color
developers are employed to develop the latent image and color
couplers are the color-providing substances and the processes
disclosed in U.S. Pat. No. 2,774,668 and U.S. Pat. No. 3,087,817
wherein complete, preformed dyes are used as color-providing
substances.
The following examples are included to further illustrate the
present invention.
EXAMPLE I
Precipitating nuclei are made in the presence of colloidal silica
by adding mixture B to mixture A, both identified below, with
vigorous agitation. ##SPC1##
The resulting solution is then coated onto paper which has been
clay- or baryta-coated in the normal way with an applicator roller
and air-knife in an amount of 0.3 liter per square meter of paper
whereupon the layer is dried rapidly with hot air. The
image-receiving sheet obtained is laid upon a silver halide
emulsion layer of an imagewise-exposed, light-sensitive material
prepared by coating a gelatin silver chloride emulsion containing
hydroquinone and 1-phenyl-3 -pyrazolidone on a paper support. Both
materials are then passed through a developing solution and
immediately thereafter the image-receiving layer and the
light-sensitive layer are squeezed into close contact to form a
sandwich. The resulting sandwich is found to be readily separable
at times up to 2 minutes. Moreover, the separated positive
image-receiving sheet exhibits an excellent dry feel and may be
written upon with a ballpoint pen directly after sandwich
separation. The density of the transfer image is found to be very
good. Upon rapid separation, that is, separation under ten seconds,
a dark-gray tone is obtained, and separation after 10or more
seconds provides good black image.
EXAMPLE II
Example I is repeated substituting gelatin for the Methocel 60 H.G.
The results are as follows: Separation of the sandwich is very
difficult after 1 minute of sandwiching. On rapid separation, that
is, under 10 seconds, a brown tone rather than a dark-gray tone is
obtained. The dry feel of the separated positive sheet is inferior
to that exhibited by that of example I at similar sandwich
times.
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.
* * * * *