Note: Descriptions are shown in the official language in which they were submitted.
1~45S7S
Background of the Invention
Field of the Invention
This invention relates to certain halo stabilizer
precursors in photothermographic elements, compositions and
processes to provide improved stability. In one of its
aspects it relates to a photothermographic element comprising
(a) photosensitive silver halide in association with (b) an
oxidation-reduction image-forming combination comprising (i)
a heavy metal salt oxidizing agent with (ii) an organic
10 reducing agent, (c) a polymeric binder, and (d) a halo organic
stabilizer precursor as described. In another of its aspects
- it relates to a photothermographic composition comprising the
described stabilizer precursors. A further aspect relates to
a method of developing a stable image in a photothermographic
element comprising the described oxidation-reduction image-forming
combination with photosensitive silver halide and the described
halo organic stabilizer precursors by overall heating the
exposed photothermographic element.
j .
Description of the State of the Art
; 20 It is known to obtain an image in a photosensitive
element by so-called dry processing with heat. The photo-
thermographic element employed for providing such an image can
contain a reducing agent, a light-insensitive silver salt of -
an organic acid, such as silver behenate, as an oxidizing agent
and a low concentration of photographic silver halide. Such
photothermographic elements are described, for example, in
U.S. Patent 3,457,075 of Morgan et al, issued July 22, 1969;
; U.S. Patent 3,152,904 of Sorensen et al, issued October 13, 1964;
British Specification 1,161,777 published August 20, 1969;
U.S. Patent 3,707,377 of Tiers et al, issued December 26, 1972
as well as in Research Disclosure, January 1973, pages 16-21. ~:
- 2 -
A~
5~75
In a photothermographic material one of the main
difficulties involves post-processing stability. secause heat
developable photographic elements are suitable for so-called
dry processing with heat and are designed to eliminate a fixing
step which normally would remove undeveloped silver, it is
necessary that a means be provided for post-processing stabiliza-
tion to enable room-light handling.
Several means have been proposed to answer the need
for post-processing stability of photothermographic elements,
such as (1) washing with water to remove undeveloped silver
salts, (2) heating to release Bronstead or Lewis acid such as
HCl, fluoride or HF from incorporated compounds such as m-nitro-
benzenesulfonyl chloride, para-toluenesulfonic acid urea addition
complex of ~-acetamidobenzenediazonium fluoroborate and (3)
che~ation of the oxidizing agent with, for example, salicylaldoxime
or benzotriazole as described in U.S. Patent 3,152,904 of Sorensen
et al, issued October 13, 1964. Another method proposed for
solving the problem of post-processing instability is to provide
a photothermographic combination in which the oxidation-reduction
image-forming combination is on ~ne sheet of material and the
latent image forming photographic silver halide is on a separate
sheet. The sheets are separated after exposure such as described
in U.S. Patent 3,152,904. A further means pDoposed for stabili-
zation in~olves swabbing a 1% solution of phenylmercaptotetrazole
onto the surface of the overall heated photothermographic material
or fubbing benzotriazole into the surface of the coating. These
proposed means for stabilization are not useful for large volume
handling of heat developable photographic materials.
It has also been proposed to provide stabilized images
- 30 in heat developa~le materials by treating t~-e developed image
:~ . . . . .- .
~.: . ' ' , , ,
~ , .
i~4S875 ~
with a solution containing certain thiol or thione compound
stabilizers. This is described, for example, in U.S. Patent
; 3,617,289 of Ohkubo et al, issued November 2, 1971. One of
the compounds proposed for this solution stabilization is
l-phenyl-5-mercaptotetrazole. Unfortunately, the addition of
this compound to photographic silver compositions provides
undesired desensitization at concentrations which produce
stabilization and toning of a developed image.
Another means of stabilization of an image in a
photothermographic material is described in Belgian Patent 768,071
published July 30, 1971. Certain stabilizer precursors which
are azole thioethers or blocked azolinethiones are employed
in photothermographic materials according to the description
in these applications. An example of a stabilizer precursor -
proposed in photothermographic materials is 5-methoxycarbonyl-
thio-l-phenyltetrazole. Unfortunately, this compound does not
always provide the desired increased stability of a heat
developed image.
Another means for post-processing stabilization of
certain photothermographic materials is described in U.S.
Patent 3,707,377 of Tiers et al, issued December 26, 1972.
- Certain polyhalogenated organic oxidizing agents, such as
tetrabromobutane, are described in certain heat developable
photographic materials to provide post-processing stabilization.
Unfortunately, multihalogenated image stabilizer precursors, such
as tetrabromobutane, do not stabilize certain photothermographic
materials as efficiently as monohalo compounds. This is
illustrated by comparing the results in following Example 7
.
, .,, ~ : -: ~
,' .
,' '' .
A~ - 4 ~
-: . . .... ,. : . ,, ~ : - . . . ... .. . ... .. . . .. . . .
1~45875
with results in following Example 11. Certain monohalo
compounds can provide surprisingly improved stabilization
without providing signi~icantly decreased maximum density.
Halogenated organic compounds have been employed in
photographic materials for various purposes, such as antifoggants.
Monohalogenated organic antifoggants for photographic
emulsions are described, for example, in U.S. Patent 3,128,187 : ~
of Sagal et al, issued April 7, 1964; U.S. Patent 3,232,762 ~ `
of Ford et al, issued February 1, 1966; U.S. Patent 2,732,303 : ~-
10 of Morgan et al, issued January 24, 1956; U. S . Patent 2,835,581
- of Tinker et al, issued May 20, 1958 and U.S. Patent 3,271,154
of Dersch, issued September 6, 1966.
There has been a continuing need for photothermo-
graphic materials, especially photothermographic materials
- comprising an image-forming combination containing photo-
sensitive silver halide in association with an oxidation-
reduction image-forming combination comprising an oxidizing
agent comprising a silver salt Or a long-chain fatty acid
with an organic reducing agent and a polymeric binder, which
20 has improved post-processing image stability, that is reduced
background density and desired maximum density, when employing
a halogen containing stabilizer precursor. There has also
been a need to provide improved incubation antifoggants for
; such silver halide photothermographic materials.
Summary of the Invention
The described improvements are provided in a photo-
thermographic eIement or composition as described by employing
as a halogen containing organic stabilizer precursor, a
stabilizing concentration of a halo stabilizer precursor,
;
` - 5 - ~: :
- , . ..
, . ' .- , . ' ~ :, -- .,: : ' . ,
.. - . ... . . .
- ~ ~ .. ... . .
1~45875
~ especially a stabilizer precursor represented by the ~ormula:
R2
Rl _ C - X .
R3
wherein X is chloro, bromo or iodo; Rl, R2 and R3 are the
same or different and each is hydrogen, alkyl, such as alkyl
containing 1 to 10 carbon atoms including methyl~ ethyl,
propyl or octyl; hydroxyalkyl, such as hydroxyalkyl
containing l to 10 carbon atoms, including hydroxymethyl,
hydroxyethyl and hydroxyhexyl; acyloxyalkyl, such as
acyloxyalkyl containing 2 to 10 carbon atoms; nitro; nitroalkyl,
such as nitroalkyl containing 1 to 10 carbon atoms, including
nitromethyl, nitroethyl and nitropropyl; aryl, such as aryl
containing 6 to 12 carbon atoms including phenyl and naphthyl;
acyl, such as acyl of the formula R4-Co- wherein R4 is alkyl
containing l to 5 carbon atoms including methyl, ethyl, propyl ~ .
and butyl, or aryl containing 6 to 12 carbon atoms, such as ~:`
phenyl and naphthyl; amido, such as amido represented by :-~
R5 0
`. the formula 6/N - C wherein R5 and R6 are the same or :
. ~ ' :
`` different and each is hydrogen, alkyl containing l to 5 carbon
atoms, such as methyl, ethyl and propyl, phenyl or naphthyl;
20 sulfonyl represented by the formula R7 - S02- wherein R7 is :~
alkyl containing 1 to 5 carbon atoms, such as methyl, ethyl ~i :
and propyl, or aryl, such as aryl containing 6 to 12 carbon
atoms, such as phenyl, naphthyl or tolyl; and wherein,
: preferably, at least one of Rl, R2 and R3 is hydroxyalkyl, .
acyloxyalkyl, acyl, amido or sulfonyl as defined. ~lkyl,
aryl, hydroxyalkyl, acyloxy~alkyl, acyl, amido and sulfonyl : -~
: .
as employed herein include substituents on the defined groups :` `:.
which do not ad~ersely affect stabilization or desired ~
- 6 - : .
:, :
~`'''" ,
: . : ,
1l~45875
properties of photothermographic materials according to the
invention. Suitable substituents include, for example,
chloro, bromo, methoxy, phenyl, hydroxy, nitro and the like.
The described improvements are provided, for example,
in the photothermographic element comprosing a support having
thereon a layer comprising (a) photosensitive silver halide in
association with (b) an oxidation-reduction image-forming
combination comprising (i) an oxidizing agent comprising
a heavy metal salt oxidizing agent, typically a silver salt
- 10 of a long-chain fatty acid, such as silver behenate and silver
stearate with (ii) an organic reducing agent, such as a sulfon-
amidophenol reducing agent, (c) a polymeric binder for the
described layer, such as poly(vinyl butyral) and (d) a
halogenated organic stabilizer precursor as described.
Detailed Description of the Invention
: ,
A variety of halogenated organic stabilizer
precursors can be employed according to the invention to
provide improved post-processing stability without adversely
affecting desired properties of the photothermographic material.
Different tests can be employed to determine whether
compounds or materials are useful image stabilizer precursors ~ -
depending upon the particular photothermographic element and
composition, desired image, processing conditions and the like.
One test which can be employed for certain photothermographic
elements is described in the following Example 1. In this
test, the compound, after incorporation in the photothermographic -
element and after imagewise exposure and overall heating of the
element as described in Example 1, should prevent buildup of
background density or minimum density above 0.10 density unit
more than the original mlnimum density without undesired stain
and without significantly adversely affecting maximum density.
- 7 -
.
~1~
- - . :
~ . : . . : :
11~45875
It is believed that the described halo organic
compounds are precursors of the moiety, compound or material
which, is formed and combines with silver ions or silver
atoms to prevent undesired instability due to room-light
exposure. However, the exact mechanism of stabilization is
not fully understood. The stabilizer precursors according
to the invention are compounds which do not prevent a redox
reaction upon imagewise exposure and heat-processing of the
described photothermographic materials, but the stabilizing
10 moiety or material formed prevents background discoloration
of the unexposed regions of the photothermographic material
due to room-light exposure.
Many of the described halo organic compounds ~-
according to the invention provide reduced fog in a photo-
thermographic material as described prior to imagewise
exposure of the photothermographic material. The described
halo compounds thus provide antifoggant action. The antifoggant
action is provided in the photothermographic material under
incubation conditions, i.e., conditions of temperatures and
- 20 humidities above normal storage temperatures and humidities.
Many of the described monohalo organic compounds are termed
incubation antifoggants for photothermographic materials as ;~-
described.
One class of useful stabilizer precursors according
to the invention comprises an alpha-monohaloketone represented
by the formula: -~
R8 _ CH - C - R9
X O , ~
wherein X is chIoro, bromo or iodo; R8 is hydrogen, alkyl
containing 1 to 10 carbon atoms, such as methyl, ethyl, propyl,
butyl, pentyl or octyl, acyl containing 1 to 10 carbon atoms,
such as acetyl, propionyl, butyryl and pentanoyl, and aryl
.. ~
~ ~ .
.. . .
.. .. . .
1(~4S875
containing 6 to 12 carbon atoms, such as phenyl and naphthyl;
R9 is amino, alkyl containing 1 to 10 carbon atoms, as described,
and aryl containing 6 to 12 carbon atoms, such as phenyl and
naphthyl.
Another class of stabilizer precursors according to
the invention comprises a monohalo sulfonyl compound represented
by the formula: R11
R - S02 - CH - R
wherein R12 is aryl, such as aryl containing 6 to 12 carbon
atoms, such as phenyl, tolyl or naphthyl; R11 is chloro, bromo
or iodo; R12 is hydrogen, alkyl, such as alkyl containing 1 to ; :
5 carbon atoms, including methyl, ethyl and propyl; amido, :
such as amido represented by the formula
13
-C0-N \ 14 wherein R13 and R14 are the same or different
and each is alkyl containing 1 to 5 carbon atoms, phenyl, .
tolyl or hydrogen.
Another class of stabilizer precursors according
to the invention comprises a monohalo-nitro lower alkane
stabilizer precursor, such as a monohalo-nitro lower alkane . -
represented by the formula:
N02
R 5 - (CH2)n - C - (CH2)m - R16
wherein X is chloro, bromo or iodo; m and n are each 1 to 5;
R15 and R16 are the same or different and each is hydroxyl, an
ester or a sulfonyl group represented by the formulae:
O O
- C - o - R17 " 17 or - S - R17
O
wherein R17 is aryl, such as aryl containing 6 to 12 carbon
atoms, including phenyl, tolyl and naphthyl, or alkyl, such
g_
. , . . ~. .
, :
104587S
as alkyl containing 1 to 5 carbon atoms, including methyl,
ethyl, propyl and butyl.
Useful stabilizer precursors as described include
the following compounds:
2-bromo-2-phenylsul~onylacetamide
2-bromoacetophenone
-chloro-~-nitrotoluene
2-bromo-2-phenylacetophenone
2-bromo-1,3-diphenyl-1,3-propanedione
a-bromo-2,5-dimethoxyacetophenone
a-bromo-y-nitro-~-phenylbutyrophenone
2-bromo-2-~-tolylsulfonylacetamide
" :
a-iodo-y-nitro-~-phenylbutyrophenone
a-bromo-_-nitrotoluene
2-bromo-4'-phenylacetophenone ~ -
2-chloro-4'-phenylacetophenone
a-bromo-m-nitrotoluene ~ ~
2-bromo-2-nitro-1,3-propanediol ~ ~-
1,3-dibenzoyloxy-2-bromo-2-nitropropane ~ ~
- 20 2-bromo-2-nitromethylene bis(phenylcarbonate) ~ -
The compound 1,3-dibenzoyloxy-2-bromo-2-nitropropane
is also known as 1,3-(2-bromo-2-nitro-trimethylene)dibenzoate.
The described halogenated organic stabilizer
precursors can be prepared by methods known in the art. For
example, the parent organic compound can be halogenated employing,
for example, bromine or chlorine. The resulting halogenated
compounds can be purified, if desired, employing purification
procedures known in the art.
The described halogenated organic compound
30 stabilizer precursors of the invention are useful in a variety
of photothermographic materials.
The useful concentration of stabilizer precursor
according to the invention will depend upon different factors
1045875
such as the particular photothermographic element, processing
tem~eratures, particular components of the photothermographic
element, desired image, desired image stability, whether the
stabilizer precursor is to be used to provide incubation anti-
foggant activity or post-processing stabiliz~tion activity and
the like. A useful concentration of stabilizer precursor
according to the invention is about 0.01 moles to about 1.0 moles
of the stabilizer precursor per mole of total silver in the
photothermographic material. An especially useful concentration
range is about 0.05 moles to about 0.5 moles of the described
stabilizer precursor per mole of total silver in the photothermo-
graphic element. When combinations of stabilizer precursors are
employed according to the invention, the total concentration of
stabilizer precursors is within the described concentration
range. The optimum concentration useful can be determined based
on the described factors.
Typical photothermographic materials in which the
stabilizer precursors of the invention are useful are described,
for example, in U.S. Patent 3,457,075 of Morgan et al, issued
July 22, 1969; U.S. Patent 3,152,904 of Sorensen et al, issued
October 13, 1964; U.S. Patent 3,429,706 of Shepard et al, issued
February 25, 1969; U.S. Patent 3,672,904 of deMauriac, issued
June 27, 1972 and Research Disclosure, January, 1973, pages
16-21.
The stabilizer precursors of the invention are especially
useful in photothermographic materials comprising (a) an oxida-
tion-reduction image-forming com~înation comprising (i~ silver
behenate, with (ii~ a sulfonamido~henol reducing agent, (b)
photosensitive silver halide, (c~ a poly(vinyl butyral) binder,
a spectral sensitizing dye, and a toning agent (also known as
1t~45875
an activator-toning agent) comprising succinimide or N-hydroxy-l,
8-naphthalimide. Such a photothermographic material in the
absence of the stabilizer precursors of the invention is de-
scribed, for example, in Research Disclosure, January, 1973, ~;
pages 16-21.
An especially useful embodiment of the invention is a
photothermographic element comprising a support having thereon
a layer comprising (a~ an oxidation-reduction image-forming
combination comprising (~) silver behenate with (ii) a sulfon-
amidophenol reducing agent, (b) photosensitive silver halide,(c~ a polymeric binder, (d) a ~pectral sensitizing dye, (e) a
toning agent, such as succinLmide or N-hydroxy-1,8-naphthalimide, ~ -
and ~f~ a sta~ilizing concentration of alpha-bromo-gamma-nitro-
beta-phenylbutyrophenone, 2-bromo-2-~-tolyl-sulfonylacetamide,
2-chloro-4'-phenylacetophenone, 2-bromo-2-nitro-1,3-propanediol,
1,3-dibenzoyloxy-2-bromo-2-nitropropane, or alpha-chloro-~-
nitrotoluene.
The described photothermographic materials according
to the invention comprise a photosensitive component which is ~ -
photosensitive silver halide. In the photothermographic materials ~ -
it is believed that the photographic silver halide or a component
resulting from the photographic silver halide acts as a catalyst `~
for the described oxidation-reduction image-forming combination.
A typical concentration range of photo~ensitive silver halide is
from about 0.01 mole to about 20.0 moles of photosensitive silver
halide per mole of silver salt oxidizing agent, for example, per
mole of silver behenate. Other photosensitive silver salts can !
be used in combination ~ith the photosensitive silver halide if
desired. Useful photosensitive silver salts include silver-dye
complexes. Preferred photosensitive silver halides~are silver
chloride, silver bromide, silver bromo~odide, silver chlorobromo-
iodide or mixtures thereof~ Very fine~grain photosensitive
: " ' -
-12- ~
. .
.. .. . . - .: - : .
. . . .. : - ~, .
.. . . . .. . . . . .. .
1~45875
silver halide is especially useful although ooarse or fine-grain '~
photosensitive silver halide can be employed if desired. The
photosensitive silver halide can be prepared ~y any of the
procedures known in the photographic art. Such procedures and
forms of photosensitive silver halide are described, for example,
in the Product Licensing Index, Volume 92, December 1971, publi-
cation 9232 on page 107, paragraph I. The photosensitive silver
halide according to the invention can be unwashed or washed, can
be chemically sensitized, can be protected against the production
o fog and stabilized against loss of sensiti-vity' =
during keeping, as described in the above Product Licensing Index
publication.
The photothermographic elements and compositions accord-
ing to the invention comprise an oxidation-reduction image-
forming combination which contains a heavy metal salt oxidizing
agent, typically a silver salt of a long-chain fatty acid. Such
heavy metal salt oxidizing agents are resistant to darkening
-i upon illumination. Typically useful silver salts of long-chain -
fatty acids are those containing about 17 to 30 car~on atoms.
Compounds which are useful silver salt oxidizing agents include:
silver behenate, silver stearate, silver oleate, silver laurate,
- silver hydroxystearate, silver caprate, silver myristate and
silver palmitate. Silver salts which are not silver salts of
long-chain fatty acids are useful heavy metal salt oxidizing
agents. Such silver salt oxidizing agents which arè useful
include, for example, silver benzoate, silver benzotriazole,
silver te~ephthalate, silver phthalate and the like. Non-silver
heavy metal salt oxidizing agents that are useful are, for
example, gold stearate, mercury behenate, gold behenate and the
like. Combinations of heav~ metal salt oxidizing agents aan be
used ~f desired.
104587S
The described photothermographic elements and composi-
tions can comprise various reducing agents. Suitable reducing
agents which can be employed with the described stabilizer pre-
cursors include substituted phenols and naphthols, for example,
bis-beta naphthols. Suitable bis-beta-naphthols include, for
example, 2,2~-dihydroxy~ binaphthyl, 6,6l-dibromo-2,2'-
dihydroxy~ binaphthyl, 6,6'-dinitro-2,2'-dihydroxy-1,1'-
binaphthyl and/or bis-(2-~ydroxy~l-naphthyl) methane. Other
reducing agents which can be employed in photothermographic
elements, according to the invention, include polyhydroxybenzenes
such as hydroquinone, alkyl-substituted hydroquinones such as
tertiary butylhydroquinone, methylhydroquinone, 2,5-dimethyl-
hydroquinone and 2,6-dimethylhydroquinone; catechols and
pyrogallols, chloro-subs~ituted hydroquinones such as chloro-
hydroquinone or dichlorohydroquinone; alko~y-substituted hydro-
quinone such as methoxyhydroquinone or ethoxyhydroquinone;
aminophenol reducing agents, such as 2,4~diaminophenols and
methylaminophenols; ascorbic acid reducing agents such as
ascorbic acid, ascorbic acid ketals and ascorbic acid derivatives;
20 hydroxylamine reducing agents; 3-pyrazolidone reducing agents
such as l-phenyl-3-pyrazolidone and 4-methyl-4-~ydroxymethyl-1-
phenyl-3-pyrazolidone and the like. Combinations of reducing
agents can be employed if desired.
Especially useful reducing agents which can be employed
in the photothermographic materials according to the invention
are sulfonamidophenol reducing agents as described in Research
Disclosure, January, 1973, pages 16-21. One especially useful
class of sulfonamidophenol reducing agents is represented by
- the formula: R5 ~ R4 ~ ~
3Q ~ ~ -
NHSO2-R
-14
.- . :. - . , . . : . : . . . . .. . .:
'' ' ' '' , ' ' ,' '" '" ~' , ' ~ ' ', '" ' ' ~' ;
.
1~45875
wherein R6 is phenyl, naphthyl, methylphenyl, thienyl, quinolinyl,
thiazyl, or alkyl containing 1 to 4 carbon atoms, such as methyl,
ethyl, propyl or butyl; R4 is hydrogen, R6SO2NH-, alkoxy con-
taining 1 to 4 carbon atoms, such as methoxy, ethoxy, propoxy
and butoxy, bromine or chlorine; R5 is hydrogen, ~romine, -
chlorine, alkyl containing 1 to 4 carbon atoms, as described, or
alkoxy containing 1 to 4 carbon atoms, such as methoxy, ethoxy
and propoxy. R , R and/~r R can contain substituent groups
which do not adversely affect the reducing properties of the
described sulfonamidophenol reducing agents or the desired
sensitometric properties of the photothermographic elements
and materials of the invention. Examples of substituent groups
which can be present are alkyl containing 1 to 3 carbon atoms
such as methyl, ethyl and propyl, chlorine, bromine and phenyl.
In some cases, it is desirable to avoid an amino group as a
substituent. The amino group, in some cases, provides an overly
active reducing agent.
It is desirable, in some cases, to employ a so-called
tonin~ agent, also known as an activator-toning agent, in the
photothermographic materials of the invention. Useful toning
agents are described, for example, in Belgian Patent 766,590
issued June 15, 1971 and in Research Disclosure, January, 1973,
pages 16-21. Combinations of toning agents can be empl~yed in
the photothermographic materials according to the invention if
desired. Typical toning agents include, for example, phthalimide, ~ -
N-hydroxyphthalimide, N-potassium phthalimide, succinimide,
N-hydroxy-1,8-naphthalimide, and N-hydroxysuccinimide. In some
cases other toning agents can be employed such as 1-(2H)-
phthalazinone and 2-acetylphthalazinone and the like. Combina-
tions of toning ag~nts can be employed if desired.
A combination or mixture of stab~llzer precursors canalso ~e used in the photothermographic materialfi of the invention.
,15~
- . - . . . . . .
. .
104587S
In addition to combinations of stabilizers within
the described formula according to the invention, other
image stabilizers or stabilizer precursors can in some cases
be employed with the stabilizer precursors of the invention.
Typical stabilizer precursors which can be employed in com-
bination with the stabilizer precursors of the invention
include, for example, azole thioethers and blocked azoline
thione stabilizer precursors as described in Belgian Patent
768,071 issued July 30, 1971.
A photothermographic element or composition as
10 described according to the invention can contain various
colloids and polymers alone or in combination as vehicles,
binding agents and in various layers. Suitable materials
; can be hydrophobic or hydrophilic. They are transparent
or translucent and include both naturally-occurring substances
such as proteins, for example, gelatin, gelatin derivatives,
cellulose derivatives, polysaccharides such as dextran, gum
; arabic and the like; and synthetic polymeric substances such
as water soluble polyvinyl compounds like poly(vinyl pyrrolidone),
acrylamide polymers and the like. Other synthetic polymeric
compounds which can be employed include dispersed vinyl compounds
such as in latex form and particularly those which increase
dimensional stability of photographic materials. Effective
polymers include water-insoluble polymers of alkyl acrylates
and methacrylates, acrylic acid, sulfoalkyl acrylates, meth-
acrylates and those which have crosslinking sites which
facilitate hardening or curing as well as those having
recurring sulfobetaine units as described in Canadian Patent 774,054.
Especially useful high molecular weight materials and resins
include poly(vinyl butyral), cellulose acetate butyrate,
3 poly(methyl methacrylate), poly(vinyl pyrrolidone), ethyl-
- 16 -
,~ A,!,
.; ~. .. : .
. . . . . . . . . . .
1C~45875
cellulose, poly(styrene), polytvinyl chloride), chlorinated
rubber, poly(isobutylene), butadiene-styrene copolymers, vinyl
chloride-vinyl acetate copolymers, copolymers of vinyl acetate,
vinyl chloride and maleic acid and poly~vinyl alcohol).
The useful concentration of reducing agent according
to the invention will vary depending upon the particular photo-
graphic element, desired image, processing conditions, particular
stabilizer precursor employed and the like. A useful concentra-
tion of reducing agent is typically from about 0.2 mole to about
2,0 moles of reducing agent per mole of photosensitive salt.
A useful concentration of reducing agent in relationship to
ox;dizing agent, such as silver behenate or silver stearate, is
t~pically from about 0.01 mole to about 20 moles of reducing
agent per mole of silver salt of a long-chain fatty acid, such
as per mole of silver behenate, in the photothermographic
material. Reducing agents can be employed in combination. When
combinations are employed, the total concentration of reducing
agent is typically within the described concentration range.
Photothermographic materials according to the invention
can contain development modifiers that function as speed- ~-
;` increasing compounds, hardeners, antistatic layers, plasticizers
:
and lubricants, coating aids, brighteners, spectral sensitizing
dyes, absorbing and filter dyes, also as described in the
Product Licensing Index, Volume 92, December, 1971, publication
9232, pages 107-110.
T~e photothermographic elements according to the
invention can comprise a wide variety of supports. Typical
supports include cellulose nitrate film, cellulose ester film,
poly(vinyl acetal~ film, poly(styrene) film, poly(ethylene
terephthalate) film, pol~(carbonate~ film, polyester films as
''. ~'.:
' ' ; ' ~''
-17-
':, : -
,
: :
lQ45875
described in U.S. Patent 3,725,070 of Hamb et al, issued April
3, 1973 and U.S. Patent 3,634,089 of Hamb, issued January 11,
1~72 and related films or resinous materials, as well as glass,
paper, metal and the like supports which can withstand the
processing temperatures employed according to the invention.
Typically a flexible support is employed.
The photothermographic compositions and other composi-
tions according to the invention can be coated on a suitable
support by various coating procedures including dip coating,
air knife coating, curtain coating or extrusion coating using
hoppers such as described in U.S. Patent 2,681,294 of Beguin
issued June 15, 1954. If desired, two or more layers can be
coated simultaneously such as described in U.S. Patent 2,761,791
- of Russell issued September 4, 1956 and British Patent 837,095.
` Spectral sensitizing dyes can be used in the described
- photothermographic elements and compositions of the invention
to confer additional sensitivity to the elements and compositions -~
of the invention. Useful sensitizing dyes are described, for
example, in the Product Licensing Index, Volume 92, December,
~ 20 1971, publication 9232, pages 107-110, paragraph XV.
After imagewise exposure of the photothermographic
element according to the invention, typically to visible light,
the resulting latent image can be developed merely by overall
heating the element to moderately elevated temperatures. This
overall heating merely involves heating the described element
to a temperature within the range of from about 80C. to about ;
250C. such as for about 0.5 to about 60 seconds. By increasing
or decreasing the length of time of heating, a higher or lower
temperature within the described range can be employed depending
upon the desired image, particular stabilizer precursor, partic-
ular reducing agent, and the like. Typically, a lQwer processing
~18~
.. ~.
11;~45875
temperature is desired. A preferred processing temperature
range is from about 115C. to about 175C. A developed image
is typically produced ~ithin several seconds, such as from
about 0.5 seconds to about 60 seconds.
Any suitable means can be used for providing the
desired processing tempera~ure range. The heating means can
be a simple hot plate, iron, roller or the like.
Processing is usually carried out under ambient condi-
tions of presaure and humidity. conditions outside normal
atmospheric pressure and humidity can be employed if desired.
The described stabilizer precursor according to the
- invention can be in any suitable location in the photothermo-
graphic material according to the invention which provides the
desired stabilized image. If desired, one or more of the
components of the photothermographic element according to the
invention can be in one or more layers of the element. For
- example, in some cases, it can beddesirable to include certain
percentages of the reducing agent, toner, image stabilizer
precursor and/or other addenda in a protective layer over the
photothermographic element. This in some cases can reduce
migration of certain addenda in the layers of the photothermo-
graphic element.
The following examples are included for a further
understanding of the invention.
EXa~ple 1
This is a comparative example. ~ -
A ~ilver behenate-behenic acid dispersion (I) is
prepared by ball-milling the following components for 64 hours:
silver behenate 168
behenic acid64 g -~
, .
-19-
.... ... ,, . ., ., .. , , ,. ". . ,
.: . . - : :. :
- . . : ., ~ . .; : .: . : : : : .
1~45875
poly(vinyl butyral) 120 g
acetone-toluene (1:1 by volume) 2 liters
The following addenda are combined with 7 ml of the
above-identified dispersion (I), mixed thoroughly and then
coated on a suitable paper support at 0.86 g Ag/m2 and 2.5 g
poly(vinyl butyral)/m2.
Poly(vinyl butyral)-silver bromoiodide 11 ml
emulsion 3 l./mole Ag, 100 g
polymer/mole Ag, 6 mole % iodide
Acetone solution containing 10% by 12 ml ~
weight 2,6-dichloro-4-benzenesulfon- -
amidophenol
Acetone-toluene-methanol solution 11 ml
(1:1:1 by volume) containing 0.5%
by weight N-hydroxy-1,8-naphthalimide
Acetone 12 ml
The material is also overcoated with the following ;
composition at 0.95 g cellulose acetate/m2.
cellulose acetate 20.0 g
~ 20 colloidal siiica (CAB-0-SIL, 2.0 g
- which is a trademark of and
produced by Cabot Co., U.S.A.)
acetone-dichloromethane (1:1 by 800 ml
volume) -
~- The dried element is exposed imagewise to tungsten
light for four seconds and then heat-processed by contacting the
element with a metal block heated to 140C for two seconds.
After a sensitometric curve is obtained of the freshly
processed sample, the coating is sub~ected to roomlight (about
3 50-60 ft.-candles from a white fluorescent bulb) for 1,2,
4, 24, 48, and 144 hours, respectively. After each time
interval a new sensitometric curve is plotted from the
processed sample. The Dmin and Dmax values are listed in
following Table I.
- 20 -
- . . .. . , .:
- - . . .
' ~ ' '.'' ' : ' '. '' :: '
1045875
Examples 2-5
Examples 2-5 are like Example l except that the coatings
now contain the concentration of ~-bromo-~-nitro-~-phenylbutyro-
phenone listed in following Table I. These coatings are image-
~ise exposed, heat processed and subjected to the roomlight
handling as described for Example l. The results are given in
following Table I.
::
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: , . . :.... ..
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o ~ o
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O . . :
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q) ~ tn ~ : ' ''
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O C~00U~~.D '' '
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~r t~ ~ ~ ~ ~ "~: ,,
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.,_1
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., s~ o oo C~ ~ o
p~ :C ~
rl ~ o o o o o
.~ ~
.~ o o~ o ~ o ~'
o o o o o
. :
.hî O ~ 0~ ~ o
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~ ~ o
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.~ f`~ N
O ~D
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Examples 6~
The procedure described in Example 1 is repeated except
that the concentration of the compounds listed in following
Table II is added to the described photothermographic composi-
tion before coating. The results are given in Table II.
2a
.
'~ .
j 30 ~
.
;~ .,:,.: `' '
-23-
1~45875
X ,1~D ~ ~ O a~
~ ~ ~ ~ o
o ~_,~ ~ ~ ~ . .
,~ oo o o o o
~ O co ao
~,,~ ~ ~ ~,
X
~r o o o o o o
a~o ~ x ~ a~
~`:1 N ~`I ~
~ ~ O O O O O O
`1! ~1 ~D~r~ ~D Otl 0
~3 ~ ~
E-~ ~r o o o o o o
I S~ ~ O ~ o
~ ~ ~ ~ N ~`I t~l
rl ~
~ ~ O O O O O O
H ~
D C ~ N~`I ~ ~ ~1
. ~!q ~1 O O g
E~ ~ co co o o
h o o o o o O ~,C
' ~: O ~
0 ~0
U~ O
` ~ O ~ 11 1` ~ N 1` ~r O ~
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I o O O O O
., I o I . .
O ~ .~:
N O ~ O * *. * * ,4 0 N . `: .
S * * * * # I I ' ' -
~ P:~ X ~ N 1
P~ X
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.
24 :
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- ' ' : '
1045875
The results in Table II illustrate that 1,2,3,4-
tetrabromobutane does not stabilize the above-described photo-
thermographic material of Example 1 as efficiently as the
monohalogenated compounds H and M.
Examples 12-14
._
These examples are approximately an equimolar comparison
(0.4 mole/mole total Ag) between compound M and 1,2,3,4-tetra-
bromobutane. The coatings are imagewise exposed, heat-processed
and tested as described in Example 1. Table III lists the
1~ sensitometric results.
~
~ -
.,.- :: .
.
-25- ~
: . . ., . . .. . , , ,,, .,
. ~
1045875
13 N ~`J ~`1
O O O
~1 o ~ I
I .
~r . .
~ O O
~1
C ~
er O O O
s~ t~
.C ~
~`I o o o
,,:
H ~J
HS: ~1 ~D ep
. `. H. e~ t~l tN ~
~ _l O O O
. ..
. ~ ~O ~ ~ .:
,m ~1 _I ~ ..
O O O '`'
` , . . . ~: .
- ~ `'.. :
0 ~ ~ U~
O
I
~ l I O O
000
., ~U~ ,.
N O ~I Q~
~' ~ C) ~ 0 3 N
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--26-
.
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~45875
:
Examples 15-27
Results similar to those of Example 2 are provided
;when the stabilizer precursor compound of Examples 2-5 is
replaced with the following compounds.
Example 15
2-bromo-2-phenylsulfonylacetamide
[~S02CHBr~?ONH2
Example 16
2-bromoacetophenone
~ C OC H2 Br
~: '
Example l?
~-~hloro-~-nitrotoluene -~
~H2Cl
1~ .~
NO2
Example 1 a
2,4'-Dibromoacetophenone :~
COCH2Br
:
, :' ~ ~ ' ' '~ ,
Br
-:
E ~ 19 -~
: . ,
2-bromo-2-phenylacetophenone
30~ ~HBrCO ~
' ,' . ,.
.. -, ,: , ., :
: . '
1~45875
Example 2~
2-bromo-1,3-diphenyl-1,3-propanedione
~ COCHBrCO
Example 21
~-Bromo-2,5-dimethoxyacetophenone
3 ~ OCH2Br
~ OCH3
: Example 22
~,
2-Bromo-2-~-tolylsulfonylacetamide
: -~
3 ~ so2cHBr
Example 23 ::
a-Iodo-Y-nitro-~-phenylbutyrophenone ~'
: N02CH2 Cl HCHICOC6H5 :
20 C6H5
Examp~e 24
~-Bromo-~-ni~rotoluene
CH2Br '- .
o
Example 25 2
2-Bromo-4'-phenylacetophenone
<~ COCH2Br ,~
.
-28-
"
1(14S875
Example 26
~-Bromo-m-nitrotoluene
CH2Br
~ `NO2
EXample 27
:
2-~romo-2-nitro-1,3-propanediol ~ :
N2
.:
HOCH2-C-CH2OH
lr
Example 28 ~ :
1,3-dibenzoyloxy-2-bromo-2-nitropropane : I
O NO2 O
~ COCH2 - C CH2(~
Example 29 ~ ;~
O NO O
11 1 li ~'
. SC2 COC~2 - C - CH20C - C2H5
.,, :
Another advantage which the described stabilizer
~ 20
- precursors provide in silver.halide photothermographic materials ;~ -
is that they provide enhanced shelf-life or incubation stability :
: at elevated temperatures.
Examp~es 30-33 ;
A silver behenate dispersion is prepared by mixing
the following components in a Waring Blender and then passing
the dispersion twice through a Manton-Gaulin Homogenizer at :
` 4~000 p8i;
... .
` silver behenate .55 g
,~- - . ., . -.
poly(vinylbutyral) 15 g
: 30
meth~lisobut~l ketone 500 ml
A photot~ermographic material is prepared by combining
-2~- .
,.
1~4S875
the following addenda and coating on an unsubbed polyethylene
terephthalate film support at 10.76 mg Ag/dm :
silver behenate ~ispersion160 ml
(preparation described above)
acetone solution containing 7.5% by 18.4 ml
weight succinimide
acetone solution containing 14~ by 37 ml
weight poly(vinylbutyral)
pol~vinylbutyral)~silver bromide 74 ml
emulsion ~90 g polymer/mole Ag,
3 l/mole Ag)
The above element is also overcoated with poly~4,4'-
(hexahydro-4,7-methanoindan-5-ylidene)diphenylene carbonate]
at a coverage of 11.84 mg/dm .
The dried element is exposed sensitometrically for
10 3 sec. with a Mark VII exposing device marketed by Edgerton,
Germeshausen and Grier, Inc. and then overall heated ~or 5
seconds at 135C. Another sam~le of the same film is stored
for 1 week at 37.8C/50% relative humidity, exposed for 10 3
seconds and heat-processed for 5 seconds at 135C. The
sensitometric data is shown in the following Table IV.
2 Examples 31-33 are like Example 30 except that the
film materials now contain 0.0035 mole, 0.0105 mole and 0.0350
mole of 2-bromo-2-p-tolylsulfonylacetamide (Example 22) per
mole ~f total silver, respectively. The materials are tested
in the same manner as described in Example 30. See Table IV ~ -
for the sensitometric date.
-
.
-30
. -
~45875 :
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a~ .Y -~ Q 1
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., ~ .
., : '.
O~D -
., ~ ~~ ~ ~ ,, .
~ .. . . ~ ..
O o o ~ -.
a
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~ ~ o
o o a~
a~ o _I ~o co o
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a.~ . .
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a~ ~ . .
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1~)45875
The above results demonstrate that the monohalogenated ~-
compou~ds can also function as incubation stabilizer precursors.
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.
'
! -
. , .
~ 20
'
~: ~
': '
-32-
~;:
. . ~ .
