Note: Descriptions are shown in the official language in which they were submitted.
5872
23
--1--
BACKGROUND OF THE INVENTION
Procedures for preparing photographic images in
silver by diffusion transfer principles are well known in
the art. For the formation of the positive silver images,
a latent image contained in an exposed photosensitive
silver halide emulsion is developed and almost concurrently
therewith, a soluble silver complex obtained by reaction
of a silver halide solvent with the unexposed and
undeveloped silver halide of said emulsion is transported,
at least in part, to a print-receiving element comprising,
preferably, a suitable silver-precipitating layer to form
the positive silver image.
Additive color reproduction may be produced by
exposing a photosensitive silver halide emulsion throuqh
an additive color screen having filter media or screen
elements each of an individual additive color, such as red
or green or blue, and by viewing the reversed or positive
silver image formed by transfer to a transparent print-
receiving element through the same or a similar screen
which is suitably registered with the reversed positive
image carried by the print-receiving layer.
As examples of suitable film structures for
employment in additive color photography, mention may be
made of U. S. Patent Nos. 2,861,885; 2,726,154; 2,944,894;
3,536,488; 3,615,426; 3,615,427; 3,615,428; 3,615,429; and
3,894,871.
The image-receiving elements of the present
invention are particularly suited for use in diffusion
transfer film units wherein there is contained a positive
transfer image and a negative silver image, the two images
being in separate layers on a common, transparent support
and viewed as a single, positive image. Such positive
images may be referred to for convenience as "integral
positive-negative images", and more particularly as
. ~J~
11~1223
"integral positive-negative transparencies." Examples of
film units which provide such integral positive-negative
transparencies are set forth, for example, in the above-
indicated U. S. Patents Nos. 3,536,488; 3,894,871;
3,615,426; 3,615,427; 3,615,428; and 3,615,429.
U. S. Patent No. 3,647,440, issued March 7, 1972
discloses receiving layers comprising finely divided non-
silver noble metal nuclei obtained by reducing a noble
metal salt in the presence of a colloid or binder material
with a reducing agent having a standard potential more
negative than -0.30. It is the thrust of the patent that
a reducing agent having a standard potential more negative
than -0.30 must be used in order to obtain nuclei of a
specific, usable size range. It is further illustrated that
stannous chloride, which does not fall within the standard
potential range, does not produce useful nuclei. The
binder materials disclosed include gelatin, polyvinyl
pyrrolidone, polymeric latices such as copoly (2-chloro-
ethylmethacrylateacrylic acid), a mixture of polyvinyl
alcohol and the interpolymer of n-butyl acrylate,
3-acryloyloxypropane-1-sulfonic acid, sodium salt and
2-acetoacetoxyethyl methacrylate, polyethylene latex, and
colloidal silica. The amount of colloid binder employed
ranges from about 5 to 500 mgs/ft2 (53.8-5380 mgs/m2) with
the nuclei ranging from 1 to 200 micrograms/ft2 (10.8 to
2150 mgS/m ).
Copending~appllcation Serial No. 269,685 filed
January 13, 1977 discloses and claims a receiving element
for use in an additive color photographic diffusion trans-
fer film unit which comprises a transparent supportcarrying an additive color screen and a layer comprisin~
noble metal silver-precipitating nuclei and a polymer;
wherein the nuclei are present in a level of about
0.1 - 0.3 mgs/ft (1.1-3.3 m~s/m ), and said poly~er is
Z~3
--3--
present at a level of from about 0.5 to 5 times the
coverage of said nuclei. Preferably, the noble metal is
obtained by reduction of a noble metal salt or complex,
and more preferably, the noble metal is palladium. The
preferred binder polymers are gelatin and hydroxyethyl
cellulose; gelatin at the low end of the nuclei-binder
ratio can be employed to provide good density, neutral
tone positive images in the receiving layer whereas the
preferred levels of other polymers, such as hydroxyethyl
cellulose are at the higher portions of the nuclei-binder
range.
Z~23
SUMMARY OF_THE INVENTION
The present invention is directed to a receiving
element for use in a silver diffusion transfer film unit
and comprises a transparent support carrying a layer of
noble metal silver-precipitating nu~lei in a polymeric
binder composition of either hydroxyethyl cellulose (HEC)
and gelatin or polyvinyl alcohol and gelatin. The nuclei
are present in the range of about 0.1 to 0.4 mgs/ft2
(1.1 to 4.3 mgs/m2); the qelatin at a level of about 0.05
to 1.5 mgs/ft2 t0.54 to 16.1 mgs/m2), and hydroxyethyl
cellulose at a level of about 0.1 to 7 mgs/ft2 (1.1 to
75.3 mgs/m2), or polyvinyl alcohol at a level of about
0.1 to 5 mgs/ft2 (1.1 to 53.8 mgs/m2). An excess of
hydroxyethyl cellulose or polyvinyl alcohol to gelatin
is employed. In a particularly preferred embodiment the
support also carries an additive color screen.
lZ~3
-5- `.
DETAILED DESCRIPTION OEI THE INVENTION
The aforementioned copending application Serial
No. 269,685 , discloses a nucleating layer with palladium
nuclei and a single polymer; at a low coverage of nuclei
gelatin is preferred while at a higher level of nuclei
hydroxyethyl cellulose is preferred. A large number of
other natural and synthetic binder materials are disclosed
as suitable, including polyvinyl alcohol.
A combination of hydroxethyl cellulose and
gelatin or polyvinyl alcohol and gelatin as the binder
for the nuclei has now been found which provides superior
photographic results. An excess of hydroxyethyl cellulose
or polyvinyl alcohol is employed compared to gelatin.
This is contrary to the disclosure of copending applica-
tion Serial No. 269,685 which set a limit on the binder
coverage and, in fact, disclosed the lower level of poly-
mer range as the preferred level to obtain a more neutral
- image tone. The hydroxyethyl cellulose or polyvinyl
alcohol and gelatin comprise the sole polymeric binder
matrix for the nuclei.
The novel silver-precipitating layers of the
present invention employing a binder matrix of HEC and
gelatin provide a more stable positive image. It is
believed that oxidation of the positive image silver,
which may result in silver being relocated behind the
wrong filter screen element producing a red effect in the
image, is inhibited. The silver image is also less
tangible and therefore more suitable for use in a motion
picture format where bending and transporting the film
unit is common. Significantly greater densities are
achieved compared to receiving layers of copending appli-
cation Serial No. 269,685, without deleterious effect on
speed, range or Dmin.
~`~
--6--
The novel silver-precipitating layers of this
invention employing a binder matrix of polyvinyl alcohol
and gelatin also provide a more stable postiive image,
particularly with respect to high humidity conditions,
as well as an increase in film speed.
In a preferred embodiment employing hydroxy-
ethyl cellulose, a ratio of 5 to 1 hydroxyethyl cellulose
to gelatin is employed. In a particularly preferred
embodiment, the silver-precipitating layer comprises
0.15 mgs/ft2 (1.6 mgs/m2) palladium, 0.2 mgs/ft2
(2.2 mgs/m2) gelatin and 1.0 mgs/ft2 (10.8 mgs/m2) of
hydroxyethyl cellulose. The levels are not critical and
can be used throughout the range specified. As levels of
HEC are increased, substantially no change in tone is
observed. However, at the higher levels, in additive color
film units, blue density increases at a greater rate than
red and green densities and the silver image tone thus
tends to become browner.
In a preferred embodiment employing polyvinyl
alcohol, a ratio of 4 to 1 polyvinyl alcohol to gelatin
is employed. In a particularly preferred embodiment
employing polyvinyl alcohol, the silver-precipitating la~er
comprises 0.15 mgs/ft2 (1.6 mgs/m2) of palladium,
0.2 mgs/ft2 (2.2 mgs/m2) of gelatin and 0.8 mgs/ft2
(8.6 mgs/m2) of polyvinyl alcohol.
The noble metals employed in the present inven-
tion include silver, gold, palladium and platinum. How-
ever, particularly superior results are achieved at the
specified coverages with palladium and, for convenience,
the invention will be descrihed primarily in terms of this
preferred embodiment.
Combinations of noble metals may be used as well
as single noble metals. In a preferred embodiment, noble
metal salts or complexes may be reacted with reducing metal
salts. Suitable compounds include the following:
~l~lZZ3
--7--
K2PdC14
PdC12
H2PtC16
AgN03
HAuC14
EXAMPLE 1
The following solutions were prepared:
Solution A
Water 3140O4 g.
Glacial Acetic Acid 305 g.
Gelatin (20% solution) 3.6 g.
SnC12- Z H 01.7 g.
Solution B
Water lg6 g
Hydroxyethyl cellulose 4.0 g.
Solution C
Water 1400 9.
PdC12 solution
(80~6 g HCl 166~6 9 PdC12/ 1. of solution) 28.7 g.
~; -8
Solution A was heated to 81-82C and 330 g. of
Solution C added with agitation. Addition was completed
within 5 seconds and the solution cooled to 24C with
continuing agitation. Water lost through evaporation was
replaced. 3.3 g. of 10~ alkyl phenoxypolyoxy ethanol
(sold underthe trademark PE 120 by NOPCO Chemical
Division of Diamond Shamrock Company) was added. After
mixing 5 min., 138 g. of 2-propanol as a coating aid was
added. To the combination of Solutions A & C (3472 g.)
L0 was added the quantity of Solution B to give the desired
HEC/gel ratios.
The utility of such nuclei layers is described
below.
EXAMPLE 2
A film unit was prepared comprising a trans-
parent polyester film base carrying on one surface, an
additive color screen of approximately 1500 triplets per
inch (590/cm) of red, blue and green filter screen elements
in repetitive side-by-side relationship; 328 mgs/ft2
(3530 mgs/m ) polyvinylidine chloride/polyvinyl formal
protective overcoat layer; a nucleating layer comprising
palladium nuclei with the coverages and polymers desig-
nated hereinafter; an interlayer formed by coating
1.9 mgs/ft2 (20.45 mgs/m2) gelatin, 2.3 mgs/ft2
(24.76 mgs/m2) acetic acid and 0.19 mgs/ft2 (2.05 mgs/m2)
octylphenoxy polyethoxy ethanol surfactant; a hardened
~elatino silver iodobromo emulsion (0.59~4mean diameter
grains) coated at a coverage of about 91 mgs/ft
(980 mgs/m2) of gelatin and about 150 mgs/ft2 (1615 mgs/m2)
of silver with about 7.18 mgs/ft2 (77.28 mgs/m2) propylene
glycol alginate and about 0.73 mgs/ft2 (7.86 mgs/m ) of
nonyl phenol polygycol ether (containing 9.5 moles of
ethylene oxide) panchromatically sensitized with
.
11~12~3
g
5,5' -dimethyl-9-ethyl-3,3'-bis-(3 sulfopropyl)
thiacarbocyanine triethyl-ammonium salt (0.53 m~/g Ag);
5,5' -diphenyl-9-ethyl-3,3'-bis(4-sulfobutyl) oxacarbo-
cyanine (0.75 mg/gAg); anlydro -5.6-dichloro-1,3-diethyl-
3'-(4"-sulfobutyl)-benzimidazolothiacarbocyanine
hydroxide (0.7 mg/g~g); and 3-(3-sulfopropyl)-3'-ethyl-
4,5-benzothia-thiacyanine betaine (1.0 mg/gAg); red,
green, green and blue sensitizers respectively; and the
following antihalo top coat.
ToP Coat mqs/f t (m~s/m )
Gelatin . 400 (4300)
Dow 620~ 204 (2195)
(carboxylated styrene/butadiene
copolymer latex
Dow Chemical Co~,
Midland, Michigan)
Propylene glycol alginate 25.7 (275)
Dioctyl ester of sodium 1.2 (13)
sulfosuccinate
Benzimidazole-2-thiol gold Au+l complex 5 (as gold) (54)
Daxad-ll*(polymerized sodium salts 0.38 (4.1)
of alkyl naphthalene sulfonic acid)
Manufactured by W.R. Grace & CoO
Cambridge J MA
Pyridinium bis-1,5 5.6 (60)
(1,3-diethyl-2-thio1-5-barbituric acid)
pentamethine oxanol
4-(2-chloro-4-dimethylamino 7 (75)
benzaldehyde)-l-(p-phenyl carboxylic
acid)-3-methyl pyrazolone-5
* Trade Mark
`:~
ZZ3
--10--
Processinq Composition A
heiqht %
Sodium hydroxide 9.4
hydroxyethyl cellulose 0.7
(sold by HercuLes, Inc.,
Wilmington, Delaware under the
tradename Natrosol 250HF*)
Tetramethyl reductic acid 9.0
Potassium bromide 0.6
Sodium sulfite 0.8
2-methylthiomethyl-4,6-dihydroxypyrimidine 9.0
4-aminopyrazolo-[3,4d]-pyrimidine 0.02
N-benzyl-a-picolinium bromide (50% solution) 2.9
Water 67.6
Trade Mark
--1 1--
Processing Composition B comprised Processinq
Composition A with about 3.3% by weight of sodium tetra-
borate~lO H2O.
Film units prepared according to the above pro-
cedure were given a 16 mcs exposure with a Xenon sensi-
tometer and processed with mechanical rollers with an
0.8 mil (0.02mm) gap disposing the processing composition
between the top coat and a polyethylene terephthalate
cover sheet. The film unit was held in the dark for one
minute and then the cover sheet was removed, retaininq
the rest of the film unit together and then drying.
The hydroxyethyl cellulose polymers employed
in the present invention are sold under the trade name
NATROSOL by Hercules Inc., Wilmington, Delaware. The
numeral designates the degree of substitution and the
letters indicate the relative viscosity type, i.e.,
HH = highest and L = lowest.
A - Natrosol 250 HHP
B - Natrosol 250 L
C - Natrosol 250 H4R
D - Natrosol 250 MH
E - Natrosol 250 HHR
More details regarding the Natrosol products
may be found in the Hercules Natrosol Products Bulletin
25 855C 7/69, provided by Hercules, Inc., Wilmington, Dela-
ware
The following ta~les set ~or~h spectrll ~ata
from film units of the present invention employing in the
receiving layer 0.2 mgs/ft2 (2.15 mqs/m2) of gelatin;
30 0.15 mgs/ft2 (l.61 mgs/m2) Pd and the designated coverage
of HEC. In Table 2 the silver coverage in the emulsion
was ll0 mgs/ft2 (1180 mgs/m2) and the average mean diameter
of the grains was 0.59,~. Control A contained no HEC and
the nuclei were formed under a blanket of nitrogen,
excluding air. Control B contained no ~IEC and the nuclei
were prepared according to the procedure of Example 8 in
11~1;~2~
copending Canadian application Serial No. 324,893*. The nuclei in
Table 2 were also made according to the procedure of Example 8 in
copending application Serial No. 324,893.
The spectral data was obtained by reading the neutral
column to red, green and blue light in an automatically recording
densitometer.
*~see also United States Patent 4,204,869.
- 12 -
;23
m ~, ,~, O
X~ o
~
~ o
P; ~, ~ ,~,,~, I O
.,, ~
D~ A
I U) U~
~ m ~
o
P~
.
oo ~
o o o o o
23
--14--
~1 o o ~ o o ~ a) d' O ~D ~ Ln C~ O O O O O
) . ~o ~
m r~
X w ~1 ~ ~ ~ n u~ ~ 1` ~ ~ ~ o ~o o o o o o
~ O ~ ~ ~ ~ ~0 ~
~ ~ o o o o o
a~ . ~ ...... .. , . O ~ ~ ~ O
o
~ ~rl
U~ U~
t~ ~ m m m m m mm m m m m m m m m m m m
m o ~
~: ~ o
E~ 0~ C)
~ ~ ~J a:, ~ ~ ~~ O N d' ~D O O O O O
O ~ O O ~ D I O ~
O ~
m m m
~I ~
o o o
h ~ ~1
JJ . ~ . ~
~ 1~
O O O
-15-
In the above tables the increase in density
obtained in film units of the present invention is shown.
- It will also be seen that advantageous results, in the
form of increased densities can be obtained over a rela-
tively wide range and that the viscosity range of the
particular HEC employed is not critical.
EXAMPLE 3
Example 1 was repeated, substituting in Solution
B 4.0g of polyvinyl alcohol (Elvanol 72-5~, sold by
E. I. duPont de Nemours & Co., Wilmington, Delaware) for
the 4.0g of hydroxyethyl cellulose.
The utility of such nuclei layers is described
below.
EXAMPLE 4
A film unit was prepared in the manner described
in Example 2, employing a nucleating layer comprising
palladium nuclei with the coverages and polymers desiqnated
hereinafter.
Processing composition A of Example 2 was
employed.
Film units prepared according to the above pro-
cedure were given a 16 mcs exposure with a Xenon sensi-
tometer and processed with mechanical rollers with an
8 mil. gap disposing the processing composition between
the top coat and a polyethylene terephthalate cover sheet.
The film unit was held in the dark for l minute and then
the cover sheet was removed, retaining the rest of the
film unit together and then air drying.
* Trade Mark
11~12Z3
-16-
: TAsLE 3
Receiving Layer Coverages (mgs/ft )
Pd qelatin polvvinyl alcohol PVA/~
ratio
0.15 0.2 0.4 2/1
0.15 0.2 o.~ 4/1
0~15 0.2 1.5 8/1
0.15 0.2 3u8 20/1
llZ23
-17-
Visual examination of the projected image
showed substantial elimination of the type of imaqe
degradation which was found in film units which did not
employ the receiving layer of the present invention.
The following tables set forth spectral data
from film units of the present invention employing as
receiving layer coverages a 4/1 polyvinyl alcohol/
gelatin ratio. In Table 2 the silver coverage in the
emulsion is 150 mgs/ft2 and the average mean diameter
of the grains is 0.73~. In Table 3 the silver cover-
- age in the emulsion is 110 mgs/ft2 and the average mean
diameter of the grains is 0.59~. The controls shown
in Tables 4 and 5 contain no polyvinyl alcohol.
The spectral data was obtained by reading the
neutral column to red, green and blue light in an
automatically recording densitometer. The 0.8 green
exposure (speed) represents the wedge density that gives
a green density of 0.8 plus Dmin and is a measure of
speed.
The source of the different polyvinyl alcohols
is set forth below.
A Elvanol 72 - 60* E.I. DuPont de Nemours,
& Co., Wilmington,
Delaware
B Gelvatol 1 - 90* Monsanto Chemical Company
St. Louis, Missouri
- C Vinol 350* Air Products and Chemicals
Inc., Wayne, Indiana
* Trade Mark
?
Z3
,
--18--
TABLE 4
max/Dmin 0 . 8 Green Type
Exposure ~Speed) PVA
Red Green Blue
1.98/0.53 2.04/0.53 2 01/0.51 1.99 --
1.78/0.53 1.81/0.48 1.79/0.49 2.21 A
1~ 98/0.53 2.03/0.52 1.99/0.52 2.15 B
1 . 95/0 . 50 1 . 95/0 .4;~ 1. 95/0 .48 2 . 19 C
~l~lZ,;~3
--19--
TABLE 5
DmaX/Dmin 0.8 Green T~pe
l~ed Green Blue Exposure (Speed) PVA_
3.26io.45 3.23/0.4S 3.01/0~42 1.77 __
3.05/0.39 3,09/0.42 3,00/0.41 1082 A
3.15/0.40 3 O 15/0.39 3.08/0.39 1 ~ 84 B
3,.08/0.43 ~.13/0.45 3.02/0.42 1.~ C
~12;~3
-20-
From the above it can be seen that significantly
increased film speed is obtained.
While the present invention is defined primarily
in terms of additive color systems, it should be understood
that the novel image-receiving elements of the present
inventions are also suitable for use in black and white
silver diffusion transfer systems.
The support employed in the present invention
: is not critical. The support or film base employed may
comprise any of the various types of transparent rigid
or flexible supports, for example, glass, polymeric films
of both the synthetic type and those derived from naturally
occurring products, etc.
The additive color screen employed in the present
invention may be formed by techniques well known in the
art, e.g. ! by sequentially printing the requisite filter
patterns by photomechanical methods. An additive color
screen comprises an array of sets of colored areas or
filter elements, usually from two to four different colors,
each of said sets of colored areas being capable of trans-
mitting visible light within a color filter elements
transmits light within one of the so-called primary wave-
lengths ranges, i.e., red, green and blue. The prepara-
tion of color screens is disclosed, for example, in U.S.
Patent Nos. 3,019,124; 3,032,008; and 3,284,208.
