Note: Descriptions are shown in the official language in which they were submitted.
FN gl5,235
~339g~5
--1--
THERMOL~BILE ACUTANCE DYES
-
This invention relates to cornpounds suitable for
use as acutance dyes in photosensitive compositions, to
the preparation of such compounds and to photosensitive
compositions containing the compounds. The invention is
particularly concerned with photothermographic compositions
of the type known as "dry silver" compositions.
Dry silver photosensitive compositions comprise
an intimate mixture of a light-sensitive silver halide~
a reducing agent for silver ions, and another silver
compound such as a silver salt of an organic acid, e.g.,
silver behenate or silver saccharine or a complexed
silver salt. The organic silver salt or complex is
substantially light-insensitive and, upon reduction, gives
a visible change. Such a mixture is usually prepared in
suspension and the resulting dispersion spread as a layer
on a suitable substrate. When dry, the layer is exposed
to a light image and thereafter a reproduction of the
image can be developed by heating the layer in the presence
of the reducing agent for silver ions such as hydroquinone
or certain substituted phenols.
It is because the exposure and development of
the layer occur without using an externally applied
developer solution, such as conventional aqueous solu-
tions, that these materials are often referred to as
dry silver light-sensitive materials. Such materials in
which minor amounts of a photosensitive sllver halide
catalyst-progenitor (the catalyst being photoinduced
silver) are associated in catalytic proximity with ma;or
. , ~ ; , ~ ~: , ; . . .
" 1~339U5
2-
amounts of a heat sensitive oxidation-reduction image
forming reaction mixture which reacts more rapidly in the
presence of the catalyst resulting upon exposure of the
silver halide are well known in the art. Examples of
such materials are described in British Patent No.
1,110,046 and in U.S. Patent Nos. 3,839,049 and 3,LI57,o75.
We believe that whenthe mixture is exposed to
light a latent image of silver is formed in the silver
halide. Thereafter, the organic silver compound can be
reduced by heating in the presence of the reducing agent,
this reduction being catalyzed image-wise by the light
exposed silver halide. By a suitable choice of temperature,
the reduction of the silver compound can be catalyzed in
the light exposed areas to give a visible darkening
while any slight reduction which occurs in the non-light
exposed areas is lnsufficient to give a marked change.
Because the silver halide acts as a catalyst-progenitor,
very small amounts of it can suffice, e.g., 0.1 to 10%
by weight of the mixture. However, large amounts, e.g.,
~0 up to 15 or even 20%~ may be desirable in some circum-
stances.
To improve the sharpness or definition of
photographic images~ a dye known as an acutance dye is
often incorporated into photosensitive compositions. To
be effective, the acutance dye will absorb at wavelengths
at which the photosensitive composition is sensitive.
The longer the path length of the light in the layer of
light sensitive composition~the greater the attenuation.
Therefore, scattered light is at-enuated or absorbed to a
- ~ . ,. . ~ . : :
- - . : .: . : : : ::
~ .. ~. . . :. . . : - :
~339~5
larger extent than light which impinges directly on a
light sensitive crystal. As a result, although the
overall speed of the composition is reduced slightly,
scattered light and other light rays which are liable to
produce a blurred image are preferen~ially absorbed. The
overall definition and sharpness of images produced in the
layer thus are increased.
An acutance dye for use in a dry silver composi-
tion is preferably heat labile, that is to say, it is
decomposed or converted by the heat development of the
dry silver composition to one or more compounds which
are colorless.
It is therefore an ob~ect of this invention to
provide dry silver compositions with acutance dyes which
absorb light at at least some of those wavelengths to
which the composition is sensitive and which are rendered
essentially colorless upon heat development of the dry
silver composition.
According to this invention there is provided a
light-sensitive composition comprising an intimate mixture
of a substantially light-insensitive silver compound
which upon reduction gives a visible change, silver
halide to provide a catalyst for this reduction, a reducing
agent for silver ions, and, as an acutance dye, a compound
in accordance with that part of the invention hereinafter
described.
According to the invention there is also
provided a compound having the general formula:
: : :, : , . :: :. :.. , - , .. .
, ~ -, : : ., : : . ;
. :;,: ,. ~,,
,: :: , :
- , : :
1~339(~
R3 R2
k / ~CH-CH~
~ =CH
R Rl R8
wherehl Rlisanla~lkyl~grOùp of from 1 to 12 carbon atoms, preferably 1 to 8
carbon atoms and more preferably 1 to 4 carbon atoms, R2 is the group
z
~ X wherein X, Y and Z are independently selected from the
group of H, N02 and CN, wi*h the proviso that at least one of X, Y, and Z
is N02. Preferably neither X nor Y is H. Preferably X, Y and Z are combina-
tions of N02 and CN or both are N02. R3, R4 and R5 are independently selected
from the group consisting of H, halogen, alkyl or alkoxy of 1 to 4 carbon
atoms, alkenyl of 2 to 4 carbon atoms, ~CH23 COOH wherein P is 0, 1, 2 or
3, -N02, -NH2, or -NHCOCH3, or any two of the adjacent groups are the atoms
necessary to form a fused on benzene ring~D represents -CH=CH-, o,-~NR7,
~ C(CH3)2, -S- -Se- or NR7, R7 represents an alkyl group of 1 to 4
carbon atoms or CH3CO-I n is 1 when k is O and k is 1 when n is 0, and m is
0, 1, 2 or 3.
The more preferred dyes of the invention are represented by the
formula:
.
-- 4 --
., ;, :: : ~ ,, . , ~ . , : ,: : " .. , :.; ,
~339~S
--5--
R8 z
R6 N~C~ X (II)
N02
2 s~ Y
rt
Rl
wherein X, Y and Z are selected from the group
o~ H, NO2, CN, perfluoroalkyl of l to 4 carbon
atoms, and halogen, with the proviso that at
least one of X, Y and Z is NO2. Preferably
neither X nor Y is H, and most preferably X
and Y are NO2 or CN, especially the oase
where both X and Y are NO2~
R6 is alkyl of l to 12 carbon atoms,
pre~erably l to 8~carbon atoms, and most
`
preferably l to 4 carbon~atoms,
7 - ~:
R is any qulnoline; dye s~ubstltuent,
preferably alkyl, alkoxy:, halogen, NO2, or
-aryl, and most preferably alkyl or alkoxy:of
l to 4 carbon atoms. There;may be more than~
one R7 group:on~the quinoline~nucleus,~and
8~
~ R is H, or~alkyl or alkoxy of l~ to~ B
carbon atoms, most preferably H or alkyl or
:
alkoxy~of l~to~3 carbon:atoms.
The substitution~of the quinoline portion of the
dyes o~ the present~:invent~lon~;is~known~in the art as
shown in DT:(W. German)~2,:2:42,761.
The~substituents R3,~R4, and~R5:~(and~R7)~may be
the same as or different from one another and each
~L~3391t~S
represents a substituent which can be present in a
cyanine dye type neterocyclic nucleus. Such substituents
are known in the art and include hydrogen or halogen,
e.g., chlorine, bromine or iodine, an alkyl or alkoxy
group containing 1 to 4 carbon atoms, an alkenyl group
containing 2 to 4 carbon atoms, -(CH2)pCOOH where p is 0,
1, 2 or 3, -NO2, -NH2, or -NHCOCH3, or any two ad~acent
groups of R3 to R5 together represent the carbon atoms
needed to complete a fused on benzene ring. Preferably
at least one, more preferably at least two, of the
substituents R3 to R5 represent hydrogen atoms. The
most preferred substituents to be represented by each of
R3 to R5 are hydrogen, chlorine or bromine atoms, or
methyl, ethyl, methoxy or ethoxy groups.
It is found that dry silver compositions con-
taining one of the above noted acutance dyes can give
excellent sharp images and that the acutance dye will be
rendered essentially colorless by the heating required to
develop the composition. This is unexpected in view of
the fact that many of these dyes are found not to be
decomposed to a colorless state when they are heated on
their own to the temperature at which the dry silver
compositions are heated for development.
The acutance dyes may be incorporated into the
dry silver compositions of the invention in an amount
from 5 x 10 to 0.1 mole of acutance dye per kilogram of
total dry solids in the composition. Preferably, however,
the dyes are incorporated in an amount of from 2 x 10 3
t~o 3 x 10 mole of acutance dye per kilogram of dry
.
- . :~ : : : : :
: : ,. ,
1133
--7--
solids in the composition.
The light-sensitive compositions of the invention
will normally be spread for use on a support, suitable
supports including, for example, paper, polymeric materials
such as polyester or polyamide ~ilm bases, and glass. The
composition will normally be prepared as a solution or
suspension which is spread as a layer on the support and
then the solvent or vehicle is evaporated to leave a dry
photosensitive layer. If desired, a coating aid or binder
such as polyvinyl butyral7 polymethyl methacrylate,
cellulose acetate~ polyvinyl acetate~ cellulose acetate-
propionate and cellulose acetate butyrate, can be
incorporated in the light-sensitive mixture.
The substantially light-insensitive silver
compound is suitably a silver salt of an organic acid or
a complexed silver salt. The organic acid may be a C12
to C29 aliphatic acid and is preferably a C16 to C~5
aliphatic acid. Examples~include silver behenate, silver
laurate, silver myristate, s31~er palmitate, and silver
stearate. Other sil~er salts of organic acids include
sil~er arachidate and silver saccharine.
The reducing agent for this substantially
light-insensitive silver compound can normally be quite
mild. Suitable examples include hydroquinone and
substituted phenols such as 1-methyl-4-hydroxy-
naphthalene, methyl gallate, catechol, phenylene diamine,
p-amino-phenol and l-phenyl-3-pyrazolidone. The
reducing agent can be incorporated into the light-
sensitive composition. Alternatively, the composition
:
- ~ :, :: .. : :, ; .- . . . .
~339~5
-- 8 --
can be placed in contact with the reducing agent after
exposure to light. For example r a light-sensitive coating
can be e~posed to a light image, placed in contact with a
layer containing the reducing agent and the image then
developed by heating. Preferably, however, the reducing
agent is incorporated in the light-sensitive composition
before this is spread on the support. Then the storage
stability of the composition can be improved by incor-
porating in the composition a small amount of a stabilizer
such as an acid stabilizer, e.g., succinic acid, benzoic
acid or salicyclic acid.
The silver halide can be present in amounts of
up to 20~ by weight of the mixture of silver compounds or
can be present in small amounts, e.g., 0.1 to 10% by
weight of the mixture of silver compounds. It can be
added as such to the substantially light-insensitive
compound or formed in s-itu by adding a soluble halide,
e.g., a mercury or sodium halide, to the substantially
light-insensitive silver compound. The silver halide
can, for example, ~y chloride, bromide or a mixture of them
and/or other silver halide.
The light-sensitive compositions o~ the invention
can include one ox more sensitizing dyes to improve their
sensitivity to parts of the spectrum other than the
shorter wavelengths. Thus dye sensitized dry silver
compositions of the present invention can contain an
additional acutance dye such as one of those described in
U.S. Patent Specification Serial No. 4,153,463
(72~Q5~Q8).
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3L~339~5
_9_
The dyes of the present invention may all be made
according to the following reaction scheme:
R4
R5~3
Rl N 7k ~ ~
C~CH-CH~mCH+F ~ X
~CH=CH ~ N2 ~
y
R4
R5 ~ R3
t-amine~ H~ + ~ ~ z
Rl N 7k ~
\~ ~C fCH-CH}mC ~X + ~-amine HF
This method is performed in the presence of a strong
tertiary amlne such as a diisopropy1ethylamine.: For
15 example, in forming ~1,4-dihydro-4-(2,4-dinitrophenyl)-
nitromethylene-l-methylquinoline (which may be also named
1,4-dihydro-1-methyl-4-(~,2,4-trinitrobenzylidene)quino-
line), one wouId react 4-nitromethyIene-l-methyl 1,4-
dihydroquinoline with 2,4-dinitrofluorobenzene in
diisopropylethylamine. Referring to the preferred
structural formula II, the~fol1owing compounds were
prepared by this method.
:
~ ~ 339~5
--10--
Melt. P. (C)
Ex. 6 8 (Decomposition
No. R R7 R X Y Temperature)
1C2H5 H H No2 No2 228-30
3 7 H H N02 No2 215
3C2H5 H H CN No2 232-4
4 CX3 H CH3 No2 No2 237-9
5C2X5 H H N02(Z) N2 230
6 CH3oCH3(4) H No2 No2 205--06
7 CH3 QCH3 H CN No2 229-31
In the table, the numbers in parentheses indicate the
position of attachment for particular substituents.
Infrared analysis and nucleus magnetic resonance analysis
confirmed the structure of each of these dyes.
Example 8
Four hundred grams of a dispersion containing
- 13 parts by weight of silver behenate in 87 parts of a
solvent composed of 67 parts by weight methylethylketone,
26 parts by welght toluene, and 7 parts by weight methyl-
isobutylketone was charged to a temperature-controlled
stirred reaction vessel at 15C. Dark room conditions
-were maintained during all subsequent work.
The following materials were added sequentially
with 20-30 minutes of stirring between separate additions.
A. 2 g of 1-methyl-2-pyrrolidinone in 6 g of
polyvinylbutyral,
B, 8 ml of 2M HBr (in ethanol) and 3.2 ml
~ of O.lM HI (in ethanol)~
C. 10 g of a copolymer derived from 91% by
weight vinylchIoride, 3% vinylacetate,
and 6% by weight vinyl alcohol polymerized
to a molecular~weight of about 23,000,
and 24 g of polyvinyl butyral,
~339~5
Do 1.8 ml of 0.5M HgBr2 tin ethanol) was
added with 5 minutes of stirring,
E 5.2 g of phthalazinone and 7.8 g of
2,6-bis-(2'-hydroxy-3~-t-butyl-5~-
methylbenzyl)-4-methylphenol,
F. 2.8 ml of a sensitizer solution having
5 mg/ml of the sensitizer in N-methyl
pyrrolidone, the sensitizer having the
formula:
= CH-CH ~
C2H5 0 >~=\
10 mg of each candidate acutance dye was
welghed into separate vessels with 3 ml of methylethyl-
ketone to dissolve or disperse the dye. 50 gram portions
of the light-sensitive dispersion formed above were com-
bined with the dye solut~ions and~to portions of methyl-
ethylketone alone as a control. All materials were
stirred for three minutes. The portions were then
allowed to stand at room temperature for 30~mlnutes, then
they were knife coated at 85 microns thickness on
polyester and dried for four minutes at 85C. Each ~
sample was topcoated with a 50 micron knife coating of a
vinylchlorlde/vinylacetate copolymer as a 5%~by weight
solution in methylethylketone.
The produced film samples were exposed at the
wavelengths indicated below through a 0.25 mm aperture
mask overlaid with a continuous denslty wedge in a
vacuum frame. This permitted an easy comparison of
image flare at equlvalent~optlcal densities after
:
-.. . . . :: ,:
S
-12-
development for 15 seconds at 12'7C in an inert fluoro-
carbon chemical bath. All dye samples had markedly less
flare than the control samples, particularly at an optical
density of 2Ø Except for the dye of Example ~, no
samples left significant visible stain after processing.
The dye of Example 8 left a magenta stain which faded
within an hour under room light. The dyes used in the
examples were as follows:
Example 8 ~ (560 nm)
10~ ~ N02
CH -N ~ C~ CN
N02
Example 9 ~ (500 nm),
~,~ N2
~\ ~
~ 7 ~ N02
N02
Example lO~ the dye of Example 1 (500 nm),
Example ll, the dye of Example 2 (500 nm),
Example 12, the dye of Example~ 5 (500 nm).
,:
,. .. .
