BACKGROUND OF THE INVENTION
Field of the Invention
[0001] This invention relates to a cobalt(III) complex-containing photographic element which
can be made negative-working or positive-working, depending upon the nature of the
exposure given.
State of the Prior Art
[0002] Cobalt(III) complexes containing releasable ligands have been utilized in non-silver
redox reactions photoinitiated by means of photoreductants or spectral sensitizers,
as disclosed, for example, in Research Disclosure, Volumes 126 and 130, October 1974
and February 1975, Publications Nos. 12617 and 13023, respectively, published by Industrial
Opportunities Limited, Homewell, Havant Hampshire P091EF, United Kingdom. Preferred
reduction products of such a reaction are cobalt(II) and amines such as ammonia. Either
of these can in turn be used to form images, the cobalt(II) being chelated by compounds
capable of forming at least bidentate chelates, or the amines being reacted with dye
precursors,
[0003] including diazo-coupler systems, to form a dye; or the cobalt(II) or amines can be
used to bleach out preincorporated dye. Such imaging processes are disclosed in Research
Disclosure, Volume 126, October 1974, Publication No. 12617, part III. Amplification
can be achieved by using a reducing agent precursor capable of forming a reducing
agent with the aforesaid reduction products, for the reduction of remaining cobalt(III)
complexes. For example, certain of said chelating compounds for cobalt(II) form, when
chelated, a reducing agent, as described in Research Disclosure, Volume 135, July
1975, Publication No. 13505, and o-phthalaldehyde will react with ammonia to form
a reducing agent, as disclosed in Research Disclosure, Volume 158, June 1977, Publication
No. 15874. Imaging elements based upon such reactions involving cobalt(III) complexes
are useful, for example, in graphic arts as room-light handling contact films, e.g.,
as an intermediate in the preparation of printing plates.
[0004] The cobalt complex imaging elements of the prior Research Disclosure can be either
negative-working or positive-working, but the same element is not both. That is, a
separate image-forming material (e.g., a dye former) is used in those instances in
which the element is to be negative-working, compared to those instances in which
the element is positive-working (e.g., by bleaching out a pre-existing dye). It would
be highly desirable to provide an imaging element wherein the same element can be
made negative or positive working, merely by controlling the processing of the element.
[0005] A further aspect of said prior cobalt complex imaging elements is that they can develop
background print-up because the unexposed photoinitiator in the background areas causes
increased D
min (minimum density) upon handling as a result of room light activation of the photoinitiator.
To avoid print-up, a peel-apart system can be used, that is, one wherein the layer
of cobalt(III) complex relied upon for the imaging is removed from the image recording
layer. Print-up is more difficult to avoid in integral systems, particularly when
the exposed photo-reductant reduces the complex at room temperatures.
[0006] Therefore, there is a need for cobalt imaging systems which are less likely to suffer
print-up when handled in room light conditions.
[0007] Metal complexes capable of releasing amines have been used prior to this invention
to thermally activate image recording means such as diazo-coupler compositions. Examples
are disclosed in U.S. Patent Nos. 3,469,984; 3,224,878; and 2,774,669. Because of
their thermal instability, such complexes generate amines when overall heated, to
cause diazo coupling or the like. There is no disclosure in this art of means for
inhibiting such dye development.
[0008] Canadian J. Chem., Volume 54, pages 3685 through 3692 (1976), teaches that certain
cobalt com- )lexes, specifically [NH
3)
5Co(III)dimethylsul- oxide]
3+, can be inhibited against thermal reduction by the addition of equimolar concentrations
of p-.oluenesulfonic acid. No suggestion is made that uch acid can be photolytically
generated.
[0009] Patents relating to the background of image ormation using amines or cobalt complexes
include .S. Patent Nos. 2,774,669; 3,102,811; 3,469,984; ,224,878; and Japanese Patent
Publication No.74/6234. escription of the Invention
[0010] The problem of providing an imaging element utilizing a radiation-sensitive, image
precursor composition containing a cobalt(III)complex which is positive or negative-working
and which avoids undesirable print-up of non-image areas is provided in accordance
with the invention by an imaging element containing, in one or more operatively associated
layers, an energy-activatable image precursor composition comprising at least a cobalt(III)
complex having releasable ligands and an image-forming material which generates an
image in response to the release of said ligands; characterized in that said imaging
element contains, in chemical association with the image precursor composition, a
photoinhibitor compound which inhibits the release of ligands from the cobalt(III)
complex or inhibits the effect of released ligands on the image-forming material upon
exposure to activating radiation.
[0011] The imaging element of the invention can be used to form a negative or positive image
by subjecting said element to a first imagewise exposure to radiation of a wavelength
which activates either the image precursor composition or the photoinhibitor, followed
by a second uniform exposure to radiation of a wavelength which activates the component
not activated by the first exposure. Brief Description of the Drawings
Figs. 1A through 1C are schematic sectional views of an element of the invention,
each view illustrating a. step in a positive-working processing of the element in
accordance with the invention;
Figs. 2A and 2B are sectional views similar to those of Figs. 1A through 1C, wherein
a negative-working process is demonstrated; and
Fig. 3 is a sectional view similar to that of Fig. 1, but illustrating still another
embodiment, Description of the Preferred Embodiments
[0012] This invention relates to an imaging element wherein an exposure activates an image
precursor composition comprising at least a cobalt(III) complex containing releasable
ligands, to form an image, and wherein an inhibiting exposure photolytically generates
the means for inhibiting such ligand release. More specifically, it has been discovered
that a photoinhibitor such as a photolytic acid generator after suitable exposure
will inhibit the release of ligands which would otherwise occur by activating exposure
of the image precursor composition.
[0013] An "image precursor composition", as used herein, is a composition as described which
when appropriately activated by exposure, produces an image by generating either a
density or by destroying a pre-existing density. Also as used herein, the precursor
composition is "energy-activatable" if it is activatable by electromagnetic energy
of any kind in areas where it is not inhibited by an already exposed photoinhibitor
of the invention. The image precursor composition can be activated by thermal, light
or electrical exposures of the type disclosed, for example, in Research Disclosure,
Volume 147, July 1976, Publication No. 14719 depending upon the circumstances. Thermal
exposure can occur through the use of infrared radiation or convection, but preferably
it is achieved through conduction. As will be readily apparent, exposure of the image
precursor composition is achieved by an energy form, such as a range of wavelengths,
that is different from that used to activate the photoinhibitor. Generally the image
precursor composition is activated by longer wavelength energy than will activate
the photoinhibitor.
[0014] In a highly preferred form, the exposure of the image precursor composition is achieved
through the use of heat or light or both together. However, as noted, if light is
used or is present in a thermal exposure, preferably it is of a wavelength or an intensity
that does not activate the photoinhibitor. Similarly, the light exposure used to imagewise
activate the photoinhibitor to inhibit image formation can include energy of wavelengths
and intensities that are incapable of activating the image precursor composition in
preferance to the photoinhibitor, as shown in examples hereinafter described. To insure
such discrimination, filters may be used, particularly for broad-band exposures. Preferably,
if thermal energy is used to expose the image precursor composition, it is generated
in a total absence of light, such as by a hot block, hot stylus, or heated rollers
in a dark room.
[0015] As used herein,, "photoinhibitor" means a single compound or a mixture of compounds
which respond to activating radiation having a wavelength greater than about 300 nm,
to inhibit the release of ligands by the cobalt(III) complex. The photoinhibitor can
comprise one or more compounds which themselves have a sensitivity that responds to
wavelengths longer than about 300 nm, or it can comprise a compound whose sensitivity
responds only to wavelengths shorter than about 300 nm, and a spectral sensitizer
which increases the native sensitivity to beyond 300 nm.
[0016] An imaging element containing the radiation-sensitive composition of the invention
can comprise one or more operatively associated layers, with the image precursor composition
being contained in one or more of the layers. That is, the image-forming material
of the image precursor composition can either be admixed with the photoinhibitor,
or it can be in a separate, adjacent layer where it responds to the ligands which
are released by the cobalt(III) complex, as is more fully described hereafter. Thus,
the photoinhibitor and the image precursor composition are in chemical association,
that is, are either admixed together in a single layer, or are in contiguous layers
either as manufactured or as processed.
Image Precursor Composition
[0017] This composition includes at least 1) a cobalt(III) complex containing releasable
ligands and 2) an image-forming material capable of generating an image upon release
of said ligands. If the cobalt(III) complex is thermally stable, i.e., it will not
release ligands in response to an exposure which is primarily thermal in nature, then
one or more destabilizer materials preferably is included, as defined and described
hereafter.
[0018] An amplifier can also be included in the image precursor composition. As used herein,
an "amplifier" is a reducing agent precursor composition or compound which interacts
with the image precursor composition to generate additional initiators of the imaging
reaction, whereby an internal gain, usually expressed as enhanced density, is achieved
compared to that which results without the amplifier. Preferably, the initiators so
generated are amines, and a highly useful example of an amplifier for generating such
additional amine initiators is phthalaldehyde. The reason for such preference is that
phthalaldehyde also functions as an image-forming material, as is hereinafter described.
Alternatively, the amplifiers can be compounds which chelate with the cobalt(II) produced
from cobalt(III). Such chelating compounds contain conjugated 7r-bonding systems capable
of forming with such cobalt(II), additional reducing agents for remaining cobalt(III)
complexes. Typical amplifiers of this class, and necessary restrictions concerning
pKa values of the anions that can be used in the cobalt(III) complex in such circumstances,
are described in Research Disclosure, Volume 135, July 1975, Publication No. 13505,
the details of which are expressly incorporated herein by reference.
[0019] Any cobalt(III) complex containing releasable ligands and which is thermally stable
at room temperature will function in this invention, whether or not it is thermally
stable within the processing temperatures used. Such complexes on occasion have been
described as being "inert". See, e.g., U.S. Patent No. 3,862,842, Columns 5 and 6.
However, the ability of such complexes to remain stable, i.e., retain their original
ligands when stored by themselves or in a neutral solution at room temperature until
a chemically or thermally initiated reduction to cobalt(II) takes place, is so well
known that the term "inert" will not be applied herein.
[0020] Such cobalt(III) complexes feature a molecule having a cobalt atom or ion surrounded
by a group of atoms, ions or other molecules which are generically referred to as
ligands. The cobalt atom or ion in the center of these complexes is a Lewis acid while
the ligands are Lewis bases. While it is known that cobalt is capable of forming complexes
in both its divalent and trivalent forms, trivalent cobalt complexes, i.e., cobalt(III)
complexes, are employed in the practice of this invention, since the ligands are relatively
tenaciously held in these complexes. and released when the cobalt is reduced to the
(II) state.
[0021] Preferred cobalt(III) complexes useful in the practice of this invention are those
having a coordination number of 6. A wide variety of ligands,« can be used with cobalt(III)
to form a cobalt (III) complex. The one of choice will depend upon whether the image-forming
material described hereinafter relies upon amines to generate a dye or the destruction
of dye, or upon the chelation of cobalt(II) to form a dye density. In the latter case,
amine ligands or non-amine ligands can be used, whereas in the former case amine ligands
are preferred as the source of initiators for the image-forming reaction. Useful amine
ligands include, e.g., methylamine, ethylamine, ammines, and amino acids such as glyci-
nato. As used herein, "ammine" refers to ammonia specifically, when functioning as
a ligand, whereas "amine" is used to indicate the broader class noted above. Highly
useful with all the embodiments of the image precursor composition hereinafter described
are the ammine complexes.. The other amine complexes achieve best results when used
with particular destabilizer materials hereinafter described, for example, photoreductants.
[0022] The cobalt(III) complexes useful in the practice of this invention can be neutral
compounds which are entirely free of either anions or cations. As used herein, "anion"
refers to non-ligand anions, unless otherwise stated. The cobalt(III) complexes can
also include one or more cations and anions as determined by the charge neutralization
rule. Useful cations are those which produce readily soluble cobalt(III) complexes,
such as alkali metals and quaternary ammonium cations.
[0023] A wide variety of anions can be used, and the choise depends in part on whether or
not an amplifier is used which requires that the element be free of anions of acids
having pKa values greater than about 3.5. Otherwise, the choice of anions is significant
only to the extent that it determines whether or not the complex is thermally stable
when heated to the temperature at which the composition or element is processed. As
used herein, "thermally unstable" means that the complex decomposes at the temperature
in question sufficiently to release enough ligands to start the intended reaction
of the image precursor composition, as described herein. If a thermally unstable complex
is used with the image-forming material alone as the image precursor composition,
the complex is preferably unstable only at temperatures greater than about 100°C.
If a thermally stable complex is to be used with a destabilizer material, the complex
is preferably stable at temperatures at least as high as 130°C.
[0024] The anions which tend to render the complex thermally unstable include those that
decompose readily to a radical, such as trichloroacetate; those forming unstable heavy
metal salts, such as azido; and those which are themselves reducing agents, such as
2,5-dihydroxy-benzoate; N,N-dimethyl-dithiocarbamate; and I-phenyl-tetrazolyl-5-thiolate.
[0026] Except for the special condition of thermal instability noted above, any anion can
be selected if an anion is necessary for charge neutralization, provided the anion
is compatible. As used herein, anions are considered "compatible" if they do not spontaneously
cause a reduction of cobalt(III) complex at room temperature. As noted, a complex
does not require anions if it is already neutral.
[0027] The following Table II is a partial list of particularly preferred cobalt(III) complex
within the scope of the invention. The suffix (U) designates those which are thermally
unstable above about 100°C.
TABLE II -- COBALT(III) COMPLEXES
[0028]
hexa-ammine cobalt(III) benzilate
hexa-ammine cobalt(III) thiocyanate
hexa-ammine cobalt(III) trifluoroacetate
chloropenta-ammine cobalt(III) perchlorate
bromopenta-ammine cobalt(III) perchlorate
aquopenta-ammine cobalt(III) perchlorate
bis(methylamine) tetra-ammine cobalt(III)
hexafluorophosphate
bis(dimeth lglyoxime)bispyridine
cobalt(III)trichloroacetate (U)
bis(dimethylglyoxime)ethylaquo cobalt(III)
cobalt(III) acetylacetonate
tris(2,2'-bipyridyl)cobalt(III)
perchlorate
aquopenta(methylamine) cobalt(III) nitrate (U)
chloropenta(ethylamine) cobalt(III) perfluorobutyrate (U)
trinitrotris-ammine cobalt(III)
trinitrotris(methylamine) cobalt(III) (U)
p-superoxodeca-ammine dicobalt(III)
perchlorate (U)
penta-ammine carbonato cobalt(III) perchlorate
tris(glycinato) cobalt(III)
[0029] The image-forming material of the image precursor composition can comprise compounds
or compositions in addition to the cobalt(III) complex and destabilizer material,
if any, or it can be the same compound as is used as a destabilizer material. It can
be a dye-forming material, or a dye which is bleachable. Examples of dye-forming materials
which also comprise destabilizer materials used to interact with the cobalt(III) complex,
as discussed hereinafter, include 4-methoxynaphthol, which forms a blue dye when oxidized,
and protonated diamine destabilizer material which when associated with a conventional
color coupler will form a dye when it is oxidized by the reduction of the cobalt(III)
complex. Examples of image-forming materials used in addition to a destabilizer material
include phthalaldehyde, also used as an amplifier; an ammonia-bleachable or color-alterable
dye (cyanine dyes, styryl dyes, rhodamine dyes, azo dyes, and pyrylium dyes); a dye-
precursor such as ninhydrin; or a diazo-coupler system. Details of these examples
are set forth in Research Disclosure, Volume 126, October 1974, Publication No. 12617,
Part III, noted above. Still another alternative is to admix with the cobalt(III)
complex, chelating compounds which will react with cobalt(II) to form a dye.
[0030] Ammonia-bleachable image-forming materials will,of course, produce an absence of
dye in the exposed areas. As will be readily apparent, ammonia-bleachable, image-forming
materials and color-alterable image-forming materials, when incorporated into an element,
preferably are used in a separate adjacent layer that is associated with the photoinhibitor
layer after the latter is exposed.
[0031] As noted above, the image precursor composition includes destabilizer materials in
those instances wherein the cobalt(III) complex is thermally stable. As is implied
by the term, destabilizer materials are those which render the otherwise thermally
stable cobalt(III) complex susceptible to release of the ligands when appropriately
exposed. The exact mechanism by which these destabilizer materials, cause the release
of the ligands from the cobalt complex is not understood in most instances, other
than that such release does occur and cobalt(II) is produced, except where inhibited
by the photoinhibitor photoproducts. Because the mechanism of these destabilizer materials
is largely uncertain, the subclasses under which various examples fall are uncertain
and not necessarily mutually exclusive. To be useful, the destabilizer materials must
be compatible with the cobalt(III) complex. Usually, this is not a problem, "compatible
destabilizer materia:ls" being used here to mean materials that do not interfere with
the complex, such as by precipitating it or by spontaneously reducing it.
[0032] Examples of destabilizer materials useful with the complex include organo-metallics
such as ferrocene and 1,1-dimethylferrocene, and tricarbonyls such as N,N-dimethylaniline
chromium tricarbonyl, as well as organic materials, and may or may not require an
amplifier such as phthalaldehyde. For example, destabilizer materials comprising 4-phenyl
catechol and quinone photoreductants, hereinafter described, do not require the use
of an amplifier compound. Other destabilizer materials will not release the ligands,
when appropriately exposed,, in amounts sufficient to generate observable dye in the
same or an adjacent layer without the presence of an amplifier such as phthalaldehyde.
Still other destabilizer materials may release sufficient ligands to cause some dye
formation, and at least some of these destabilizer materials can achieve much higher
density if an amplifier is included. Therefore, in many of the embodiments of the
invention, phthalaldehyde comprises part of the image precursor composition, for preferred
results, whether or not it actually is required to produce observable results.
[0033] The behavior of phthalaldehyde in an image precursor composition appears to involve,
in the preferred embodiments, the formation with ammonia of an adduct which is a reducing
agent (see structure A in equation 1 below). The adduct itself causes reduction of
remaining cobalt(III) complex and releases more ligands. Such release produces an
internal gain.

The initial NH
3 comes from the cobalt(III) complex on exposure, either because of its own thermal
instability, or because of activation by a destabilizer material, by one of several
mechanisms described hereafter. Phthalaldehydealso forms a dye imaging material, oligomer
(B), in addition to its amplifying function as a reducing agent precursor for cobalt(III).
Further explanation can be found in DoMinh et al, "Reactions of Phthalaldehyde with
Ammonia and Amines", J. Or
g. Chem. Vol. 42, Dec. 23, 1977, p. 4217. Useful destabilizer materials are the following
thermally responsive organic materials and equivalents thereof:
(a) 4-Phenyl catechol.
(b) Sulfonamidophenols and naphthols such as 4-phenylsulfonamido-2,6-dichlorophenol
and 4-phenylsulfonamido-2-methyl-l-naphthol.
(c) Other aromatic alcohols such as 4-methoxynaphthol and 1,4-dihydroxynaphthalene.
(d) Pyrazolidones such as 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone
and the like.
(e) Acids having the formula:

wherein:
[0034] Z represents from about 4 to about 8 carbon atoms necessary to complete 1 or more
aromatic or cycloalkyl ring such as a benzene, a naphthalene or a cyclohexane ring.
[0035] Suitable examples of such acids include, for example, phthalamic acid, 2-carboxy-cyclohexylcarboxyamide
and amine salts thereof, including 2-carboxy-cyclohexylcarboxyamide triethanolamine
salt, and the like.
(f) Ureas having the formula:

wherein: T represents S or 0; and R represents a hydrogen atom, an o-hydroxyphenyl
group or an o-carbamoylphenyl group. Suitable compounds include: Urea, thiourea, 2-hydroxyphenyl
urea and the like.
(g) Salts having the formula:

wherein:
M represents a carbon or nitrogen atom
T' represents a chemical bond or an alkylene group containing from 1 to 3 carbon atoms,
and Z1 represents from about 4 to about 6 nonmetallic atoms necessary to form an aromatic
carbocyclic or heterocyclic ring.
Suitable examples of such salts including 1-(β-aminoethyl)-2-imidazolidinone trichloroacetate,
2-amino-2-thiazoline trichloroacetate, anilinium trichloroacetate and the like.
(h) Morpholine precursors having the formula:

wherein: Z2 represents from about 4 to about 8 non-metallic atoms required to complete one or
more heterocyclic rings; one example of such precursors being 3,3-bis(morphilino)oxindole.
(i) Aminimides in polymeric or simple compound form containing the structure:

including, for example, (N-methypiperidine) 1-naphthoylimide; (trialkylamine) cinnamimides;
bis(dialkyl-2-hydroxypropylamine) adipimides; (dialkyl-2-hydroxypropylamine) palmitimides
or laurimides; bis(trialkylamine) sebacimides or azelamides; 2,2'-(p-phenylenebis-β-acryloyl)-bis-[1-hydroxypropyl-1,1-dimethylhydrazinium]
dihydroxide bis(inner salt); and polymers having a repeating unit of the formula:

polymers having repeating units with pendant aminimide groups of the formula:

those described in U.S. Patent No. 4,016,340, issued April 5, 1977, and in Research
Disclosure, Vol. 157, May 1977, Publication Nos. 15732, 15733 and 15776; (trialkylamine)
arylimides such as (trimethylamine) benzimide and(trimethylamine) naphthimide, including
arylimides substituted with hydroxy, lower alkyl or nitro; and trialkylamine aryl
sulfonimides such as trimethylamine-p-toluenesulfonimide.
.(j) Amido-triazoles having the formula:

wherein:
R represents a hydrogen atom or an alkyl group having from 1 to about 5 carbon atoms,
such as methyl, ethyl, iso-propyl and the like;
R2 and R3 either both represent hydrogen atoms or taken together form an aromatic, a cycloalkyl
or a heterocyclic ring; and
Z3 represents from 4 to 8 nonmetallic atoms necessary to complete one or more substituted
or unsubstituted aromatic ring.
Such amido-triazoles including, for example, 5-methyl-1-(2)-N-(phenylcarbamoyl)benzotriazole,
5, 6-dichloro-1-(2)-N-(dimethyl carbamoyl) benzotirazole.
(k) Thiolate precursors having the formula:

wherein:
R4 is lower alkyl containing from 1 to 5 carbon atoms, for example, methyl, ethyl, propyl
and the like;
R5 is carbamoyl or an unsubstituted heterocyclic or aromatic ring or a substituted aromatic
ring containing from about 6 to 8 nonmetallic ring atoms, for example, 2-pyridyl,
phenyl, 4-nitrophenyl and the like; and
Z4 is the nonmetallic atoms required to complete a substituted or unsubstituted heterocyclic
ring containing from about 4 to about 9 atoms. Examples of such precursors include
thiazolidines, such as 2-methyl-2-carboxamidothiazolidine, substituted benzothiazolines
such as 2-methyl-2-[2-pyridyl]-benzothiazoline and 2-methyl-2-[4-nitrophenyl]-benzothiazoline.
(1) Blocked mercaptotetrazoles having the formula:

wherein:
R6 represents a hydrogen atom or a phenyl group and,
R7 represents a heat-removable group selected from the group consisting of:






(m) Cyclic imides having the structure:

wherein:
Z5 represents the non-metallic atoms necessary to complete one or more heterocyclic
rings, and,
R8 and R9 are the same or different and each represents a carbonyl or methylidyne group. Such
cyclic imides include, for example, succinimide, hydantoin and substituted hydantoin,
phthalimide, oxazolinedione and the like.
(n) Barbiturates such as 5-n-butylbarbituric acid, and those having the structure:
wherein:

R10 represents a hydrogen atom or an alkyl group having from 1 to 5 carbon atoms, such
as methyl, ethyl, propyl and the like;
R11 represents a hydrogen atom or an alkyl group having from 1 to 5 carbon atoms such
as methyl, ethyl, propyl, n-butyl and the like; and
R12 represents an alkyl group having from 1 to 5 carbon atoms, such as methyl, ethyl,
peopyl, and the like, or an aralkyl group such as benzyl; and
(o) Protonated arylene diamines having the structure:

wherein:
Ar represents a substituted or unsubstituted arylene group containing from 6 to about
20 carbon atoms,
R13 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms,
m is 2 or 3, and,
n' and n" are each 1, 2 or 3; provided that the sum of n' and n" is 3. Useful protonated
p-phenylene diamines include those which are characterized by the loss of the extra
proton when heated, creating the unprotonated form which undergoes a redox reaction
with the cobalt(III) complex.
(p) Polymers having repeating units with the structure:

wherein:
R14 represents an organic polymer chain;
R represents an organic moiety or a carbon-to-carbon bond;
Ar is arylene including substitued arylene, such as phenylene and naphthylene, wherein
the substituents, if any, are electron withdrawing groups such as nitro, sulfoalkyl
containing from 1 to 5 carbom atoms, halogen such as chloride, fluoride and the like,
and substituted alkyl such as trihalo- substituted methyl; and
R16 represents a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms.
[0036] All of the preceding destabilizers induce the release of the ligands from the cobalt(III)
complex in the presence of heat. As noted, they may or may not require the presence
of an amplifier-dye former such as phthalaldehyde. Some of them, such as destabilizer
materials (a) through (d), are quite clearly reducing agents per se. Some like destabilizer
material (k) are heat-responsive reducing agent precursors. Some, such as destabilizer
material (e) and others are heat-responsive amine precursors. They are particularly
useful with amine-responsive reducing agents and reducing agent precursors such as
phthalaldehyde that form reducing agents in the presence of amines. Some such as destabilizer
materials (h), (i) and (j) are believed to be base precursors which form a base in
the presence of heat. Destabilizer materials (a) through (d) which are direct reducing
agents do not require the presence of an amplifier such as phthalaldehyde, although
an amplifier is effective to increase the speed of an element or composition of the
invention which incorporates these compounds.
[0037] Quinone photoreductants are yet another class of destabilizer materials which are
useful in inducing the release of amines from the cobalt
[0038] complex. The quinones which are particularly useful as photoreductants include ortho-
and para-benzo- quinones and ortho- and para-naphthoquinones. phenanthrenequinones
and anthraquinones. The quinones may be unsubstituted or incorporate any substituent
or combination of substituents that does not interfere with the conversion of the
quinone to the corresponding reducing agent. A variety of such substituents are known
in the art and include, but are not limited to, primary, secondary and tertiary alkyl,
alkenyl and alkynyl, aryl, alkoxy, aryloxy, alkoxyalkyl, acyloxyalkyl, aryloxyalkyl,
aroyloxyalkyl, aryloxy- alkoxy, alkylcarbonyl, carboxy, primary and secondary amino,
aminoalkyl, amidoalkyl, anilino, piperidino, pyrrolidino, morpholino, nitro, halide
and other similar substituents. Aryl substituents are preferably phenyl substituents.
Alkyl, alkenyl and alkynyl substituents, whether present as sole substituents or in
combination with other atoms, typically contain 20 or fewer (preferably 6 or fewer)
carbon atoms.
[0039] A preferred class of photoreductants are internal hydrogen source quinones; that
is, quinones incorporating labile hydrogen atoms. These quinones are more easily photo-reduced
than quinones which do not incorporate labile hydrogen atoms.
[0040] Particularly preferred internal hydrogen source quinones are 5,8-dihydro-l,4-naphthoquinones
having.at least one hydrogen atom in each of the 5-and 8-ring positions. Other preferred
incorporated hydrogen source quinones are those which have a hydrogen atom bonded
to a carbon atom to which is also bonded the oxygen atom of an oxy substituent or
a nitrogen atom of an amine substituent with the further provision that the carbon-to-hydrogen
bond is the third or fourth bond removed from at least one quinone carbonyl doubled
bond. As employed in the discussion of photoreductants herein, the term "amine substituent"
is inclusive of amide and imine substituents.
[0041] Further details and a list of useful quinone photoreductants of the type described
above are set forth in Research Disclosure, Volume 126, October 1974, Publication
No. 12617, published by Industrial Opportunities Limited, Homewell, Havant Hampshire
P091EF, United Kingdom, the contents of which are hereby expressly incorporated by
reference. Still others which can be used include 2-isopropoxy-3-chloro-1,4-naphthoquinone
and 2-isopropoxy-1,4-anthraquinone.
[0042] As noted above, photoreductants do not require the use of an amplifier, but such
a use gives improved results.
[0043] It will be appreciated from the foregoing that, unlike the other reducing agent precursors
or other destabilizer materials described heretofore, the quinone photoreductants
rely upon a light exposure between about 300 nm and about 700 nm to form the reducing
agent which reduces the cobalt(III) complex. It is to be noted that thermal irradiation
is not needed, after the light exposure, to cause the redox reaction to take place.
However, an additional thermal exposure can be used to drive the reaction to completion.
Furthermore, heat is desirable to insure the formation of dye B described above. The
activity of some of the above described destabilizers, particularly those that respond
to thermal radiation, can be enhanced by the addition of a dodecanamide.
Photoinhibitor
[0044] Photoinhibitors which are sensitive to radiation longer than 300 nm are selected
because the plastic film supports for the imaging elements and the optical glass in
the exposing system absorb radiation shorter than 300 nm. However, photoinhibitors
which are sensitive only to radiation shorter than 300 nm are useful in conjunction
with spectral sensitizers. Such UV-sensitive photoinhibitors include carbon tetrabromide,
2-tribromomethyl sul- fonylbenzothiazole, 2-bromo-2-tosylacetamide, 2,2-dibromo-2-phenyl-sulfonylacetamide,
s-tribromoethanol and 2-bromo-2-nitro-l,3-trimethylene glycol dibenzoate. Useful spectral
sensitizers include rhodamine, carbocyanine and cyanine dyes, Eosin and Erythrosin,
triphenylmethane dyes, thiazine dyes, anthroquinonoid dyes and styryl dyes. Specific
examples of such sensitizers are disclosed in Yamada et al U.S. Patent No. 3,503,745.
[0045] Preferred embodiments are those in which the photoinhibitor comprises a composition
free of accompanying spectral sensitizers. Highly useful examples of such photoinhibitors
are photolytic acid generators, although it is not known whether all photolytic acid
generators will function as photoinhibitors. 0-nitrobenzaldehyde is a known photolytic
acid generator which is not useful because it complexes with cobalt, and is therefore
incompatible in the composition of the invention. Therefore, only those photolytic
acid generators are useful which are capable of inhibiting the release of amines without
interfering with the desired reaction in some other way.
[0046] Any photoinhibitor having the desired property of inhibiting the release of amines
in response to an exposure, can be utilized. Where the mixture of image precursor
composition and photoinhibitor is intended to be used as a dry coating composition,
it is preferable that the photoinhibitor be capable of being coated without extensive
volatilization. Where a photoinhibitor is to be used with a photoreductant, each of
the two photoresponsive compounds are selected so that their wavelengths of maximum
absorption do not overlap appreciably.
[0047] Examples of useful photoinhibitor compounds are photolytic acid generators having
an inherent sensitivity to radiation of a wavelength longer than about 300 nm., including
the following materials as well as equivalents thereof:
(a) heterocyclic compounds containing at least one trihalogenated methyl group, preferably
those with a chromophore substituent, such chromophores being any unsaturated substituent
which imparts color to the compound, for example, those disclosed in U.S. Patent No.
3,987,037;
(b) o-nitroacetanilides;
(c) anthranilium salts such as those having the structure:

wherein:
R17 represents a hydrogen atom, a phenyl group or an alkyl group containing from 1 to
about 4 carbon atoms, such as methyl, ethyl, isopropyl and the like;
R18 represents an alkyl group containing from 1 to about 4 carbon atoms, such as methyl,
ethyl, isopropyl and the like, or a 1-adamantyl group;
R19 represents a hydrogen or a halogen atom such as chloride, bromide or the like; Z
represents

or

and
R20 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; and

is a suitable anion. Useful examples include N-methyl-3-phenyl-2,1-benzisoxazolium
perchlorate and N-methyl-3-phenyl-2,1-benzisoxazolium fluorosulfonate; and
(d) other halogenated organic compounds such as idoform and the like. Highly preferred
class (a) photoinhibitors are those having the formula:

wherein:
E represents a hydrogen atom, a methyl or trihalomethyl group;
R21 represents a hydrogen atom or an alkoxy group having from 1 to 5 carbon atoms, such
as methoxy, ethoxy and the like;
R22 represents a hydrogen or a halogen atom such as chloride, fluoride and the like,
a nitro group or an alkyl, dialkylamino, or alkoxy group containing from 1 to 5 carbon
atoms in the alkyl portion such as methyl, ethyl, isopropyl and the like;
R23 represents a hydrogen atom or an alkoxy group having from 1 to 5 carbon atoms, or
together with R24 comprises the non-metallic atoms necessary to complete an aromatic ring;
R24 represents a hydrogen atom or together with R23 comprises the non-metallic atoms necessary to complete an aromatic ring; Z7 represents the non-metallic atoms necessary to complete one or more substituted or
unsubstituted heterocyclic rings containing from 6 to 10 atoms, such as S-triazine,
quinoline, quinoxaline, pyrazine, pyrimidine, and the like.
m" is 0, 1 or 2; and
X" represents a halogen atom such as chloride, bromide, and the like. Particularly
useful examples include S-triazines having the formula:

wherein:
X", R21, R22, R23, and R24 are as defined above, and
Y is the same or different from X" and is selected from the group consisting of halogen
and hydrogen, at least one of X" and Y being halogen. Class (b) photoinhibitors are
highly preferred which have the formula:

wherein:
R25 represents an alkyl group having from 1 to 3 carbon atoms, an aralkyl group having
from 7 to 8 carbon atoms, such as benzyl, phenethyl and the like, or when taken together
with R26, the atoms necessary to complete a fused heterocyclic ring such as indole and the
like;
R26 represents a halogen atom such as chlorine, bromine and the like, or together with
R25 it forms a fused heterocyclic ring;
R27 represents a hydrogen atom or an alkoxy group having from 1 to 3 carbon atoms, such
as methoxy, ethoxy and the like; and
X"' represents a halogen atom such as a chlorine, bromine or flourine atom.
[0048] The following Table I is a partial listing of useful photoinhibitors of the invention:

Elements
[0049] In the simplest form of the invention an imaging element comprises a support coated
with a single layer containing an image precursor composition and a photoinhibitor
as described above. Alternatively, the image precursor composition and the photoinhibitor
can be divided into a plurality of integral layers. Alternatively the outermost layer
can be coated on a separate support and disposed in reactable association subsequently,
such as after exposure of the photoinhibitor composition. For example, the image-forming
material can be included either as an integral portion of the element of the invention,
or it can be subsequently associated therewith as a separate image-recording layer.
In those embodiments wherein the image-forming material is an integral part of the
element, it can either be admixed with the image precursor (cobalt(III) complex) preferably
as a dye-forming material, or it can be in a separate, adjacent layer. In those embodiments
wherein it is admixed with the cobalt(III) complex, it is highly preferred that the
image-forming material is also an amplifier, such as phthalaldehyde which also functions
as a reducing agent precursor.
[0050] Yet another alternative is to imbibe the photoinhibitor into the image precursor
composition, such as by spraying or otherwise applying a solution of the photoinhibitor
to the element already containing the precursor composition.
[0051] Preferably the image precursor composition and photoinhibitor are contained in a
layer or layers coated onto a support. Any conventional photographic support can be
used in the practice of this invention. Typical supports include transparent supports,
such as film supports and glass supports, as well as opaque supports, such as metal
and photographic paper supports. The support can be either rigid or flexible. The
most common photographic supports for most applications are paper and transparent
film supports. Suitable exemplary supports are disclosed in Product Licensing Index,
Volume 92, December 1971, Publication No. 9232, at page 108, and Research Disclosure,
Volume 134, June 1975, Publication No. 13455, published by Industrial Opportunities
Limited, Homewell, Havant Hampshire P091EF, United Kingdom. The support can incorporate
one or more subbing layers for the purpose of altering its surface properties so as
to enhance the adhesion of the radiation-sensitive coating to the support.
[0052] A binder can be included in the radiation-sensitive composition layer. Any binder
compatible with cobalt(III) complexes can be used, for example, the binders listed
in the aforesaid Publication No. 12617 of Research Disclosure, expecially paragraph
I(D), the details of which are expressly incorporated herein by reference. Typical
of such binders are acetates, cellulose compounds, vinyl polymers, polyacrylates and
polyesters. In those embodiments relying upon phthalaldehyde as the dye-forming material
and/or as an amplifier, it is preferred that the binder be selected which will maximize
the minimum neutral densities produced during exposure and development. Highly preferred
examples of such binders include certain polysulfonamides, for example, poly(ethylene-co-l,4-cyclohexylenedimethylene-l-methyl-2,4-benzenedisulfonamide)
and poly(ethylene- co-hexamethylene-l-methyl-2,4-benzenedisulfonamide), and poly(methacrylonitrile).
[0053] The coating solvent selected will, of course, depend upon the makeup of the composition,
including the binder if any. Typical preferred solvents which can be used alone or
in combination are lower alkanols, such as methanol, ethanol, isopropanol, t-butanol
and the like; ketones, such as methylethyl ketone, acetone and the like; water; ethers,
such as tetra-- hydrofuran, and the like; acetonitrile; dimethyl sulfoxide, dimethylformamide
and chlorinated hydrocarbon solvents which are not effective as acid generators, because
they volatize out of the coating. The proportions of the non-binder reactants forming
the composition to be coated on the imaging element can vary widely, depending upon
which materials are being used.
[0054] A useful range of coating coverage of cobalt(III) complex is between about 5 and
about 50 mg/dm .
[0055] Since a cobalt(III) complex is always present, the molar amounts of other components
are expressed per mole of complex. Thus, if destabilizer materials are incorporated
in the composition in addition to cobalt(III) complex, they can vary widely such as
from 0.004 moles of ferrocene to 5 moles of other destabilizers per mole of complex.
For example, 5-n-butylbarbituric acid can be present in an amount of between about
0.005 moles and about 5 moles per mole of the complex. The photoinhibitor can be present
in an amount from 0.005 to 2.5 moles per mole of cobalt(III) complex. For example,
2,4-bis (trichloromethyl)-6-(p-anisyl)-s-trizaine can be present in those amounts.
[0056] Typically, the energy sensitive composition is coated onto the support in a solution
by such means as whirler coating, brushing, doctor-blade coating, hopper coating and
the like. Thereafter, the solvent is evaporated. Other exemplary coating procedures
are set forth in the Product Licensing Index, Volume 92, December 1971, Publication
No. 9232, at page 109, published by Industrial Opportunities Limited, Homewell, Havant
Hampshire P091EF, United Kingdom. Addenda such as coating aids and plasticizers can
be incorporated into the coating composition.
[0057] In certain instances, an overcoat for the radiation-sensitive layer of the element
can provide improved handling characteristics, and can help to retain otherwise volatile
components. Useful examples include crosslinked gelatin overcoats crosslinked with
a crosslinking agent such as hexamethoxy methyl melamine, and polymers having the
recurring units:

wherein:
R28 represents a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms;
R29 represents an alkylene group having from 1 to 3 carbon atoms;
R30 represents an alkyl group having from 1 to 3 carbon atoms;
m' is 1 or 0;
Z8 represents from 3 to 8 non-metallic atoms necessary to complete one or more saturated
or unsaturated heterocyclic ring;
D represents -NH- or -0-; and
x, y, z and z' represent weight percents of the recurring units of the polymer and




[0058] The preferred form of the overcoat is a dual coating first of gelatin crosslinked
as noted, and as a final coat, a layer of cellulose acetate having an acetyl content
of 19 weight percent and an ash content of 0.04 weight percent.
[0059] Further details of the imaging element, and the process of use, can be understood
by reference to the drawings. In Fig. lA, element 10 comprises a support 12 and a
layer 14 containing, in admixture, an energy-activatable image precursor composition
designated by wavy lines, a photoinhibitor, and an image-forming material such as
a dye-forming material. The element is exposed through an image 18 to radiation which
activates the photoinhibitor, preferably light, designated by arrows 16. The radiation
activates the photoinhibitor in portions 20 and 22 of Fig. 1B to inhibit the image
precursor composition, as indicated by the absence of wavy lines, but not in the unexposed
portion 24.
[0060] Imaging elements containing light-activatable photoreductants are usable even though
they also contain light-activatable photoinhibitors because the photoinhibitors are
generally activated more rapidly than the photoreductants. Generally the photoinhibitors
are activated by shorter wavelength radiation than the photoreductants. Therefore
it may be desirable to interpose an optional filter 25, shown in phanton in Fig. lA,
which transmits shorter wavelength radiation 16 that activates the photoinhibitor
but does not transmit longer wavelength radiation that activates the photoreductant.
For example, if the photoinhibitor is iodoform and the image precursor composition
includes a quinone photo- reductant, a "Wratten 18A" filter, manufactured by Eastman
Kodak Company, can be used. Wratten' is a trade mark
[0061] Thereafter, as shown in Fig. 1B, the entire element 10 is given a uniform exposure
to thermal radiation or light which activates the image precursor composition as indicated
by arrows 26. If the image precursor composition contains a photoreductant, the uniform
exposure is to light and it is necessary to prevent the photoinhibitor in portion
24 from responding. A preferred method for accomplishing this is the interposition
of a suitable filter 28, shown in phanton in Fig. lB. Such a filter is selected to
cut off the light wavelengths which are necessary for the photo-activation of the
photoinhibitor, and to transmit the wavelengths, usually longer, useful in activating
the photoreductant. For example, if the photoinhibitor is iodoform and the image precursor
composition includes a quinone photoreductant, a "Wratten 2A" filter can be used.
[0062] The effect of the uniform exposure of the image precursor composition is to generate
a dye in portion 24, Fig. 1C, and none in the inhibited portions 20 and 22, thus rendering
element 10 positive-working. The dye is schematically shown by the superimposed straight
lines.
[0063] For example, the presently preferred embodiment features phthalaldehyde as an amplifier
and dye-forming material incorporated in layer 14, along with an s-triazine photoinhibitor
such as 2,4- bis(trichloromethyl)-6-(p-anisyl)-s-triazine, hexa-ammine cobalt(III)
trifluoroacetate complex and either 5-butylbarbituric acid or diphenylhydantoin destabilizer
material. Imagewise exposure to light activates the photoinhibitcr. A subsequent overall
thermal exposure, such as at 150°C for the barbituric acid and 130°C for the hydantoin,
causes reduction of the complex, release of ammonia, formation of the adduct of phthalaldehyde
further reduction of remaining cobalt (III) complex, release of more ammonia, and
amplified dye formation.
[0064] Alternatively, the image-forming material of the image precursor composition, which
can be, for example, phthalaldehyde as noted above, can be disposed in an adjacent
layer 30, shown in phanton in Figs. 1B and 1C. As shown, layer 30 can be positioned
as an overlay in contact with element 10 after the imagewise exposure as shown in
Fig. lA, or. alternatively, it can be overcoated onto layer 14 as an integral portion
of element 10. In either case the uniform exposure which activates the image precursor
composition, arrows 26, will develop the release of NH
3 ligands in portion 24 only. The NH
3 ligands will migrate to portion 32 of the layer 30 as shown by arrows 34, where either
a dye is formed or a preincorporated dye is bleached or altered in color. Thereafter,
layer 30 can be removed from or retained on, element 10.
[0065] In Fig. 2A, the same element as in Fig. 1A is given a different treatment to render
it negative-working. Specifically, the same identical element, regardless of the image
precursor composition used, is rendered negative-working merely by changing the exposure
sequence. That is, the process step effectuated by imagewise exposure is now an exposure
capable of activating the image precursor composition rather than the photoinhibitor.
Parts similar to those previously described bear the same reference numerals to which
the distinguishing suffixes "a" are added. For purposes of comparing this negative-working
mode to the positive-working mode previously discussed, it is again assumed that the
image-forming material of the image precursor composition is a dye-forming material.
Thus, element 10a comprises the same coating 14a on support 12a as described before.
However, imagewise exposure (arrows 16a) through image 18a must not activate the photoinhibitor.
If exposure 16a is thermal, only the image precursor composition is activated. In
such instance, image 18a is selected so as not to significantly reradiate in the "dark"
areas. If however, exposure 16a is broadband light radiation, it preferably passes
through a suitable filter 28a, shown in phantom, selected to prevent transmission
of radiation sufficient to activate the photoinhibitor, but to allow transmission
of radiation sufficient to activate the image precursor composition. As noted before,
a "Wratten 2A" filter is effective if the photoinhibitor is iodoform and the image
precursor composition contains a quinone photo- reductant destabilizer. In the case
where a photo- reductant destabilizer material is used, an optional subsequent thermal
exposure can be included.. Dye imagewise develops in areas 20a and 22a, Fig. 2B.
[0066] The element is then given overall exposure, arrows 26a of Fig. 2B, to radiation which
activates the photoinhibitor to prevent background printup. As in the case of the
imagewise exposure step of Fig. lA, it may be desirable in some instances to interpose
a suitable filter 25a, shown in phantom, to insure that the exposure 26a does not
activate the image precursor composition.
[0067] As in the case of the process shown in Figs. 1B and 1C, the negative image can be
formed instead in an adjacent layer, not shown, by transfer of ligands thereto from
layer 14a.
[0068] If the photoinhibitor includes a compound having a response only to radiation of
wavelengths shorter than about 300 nm. and a spectral sensitizer, as described above,
it is contemplated that the composition and/or element of the invention is one in
which the photoinhibitor and the image precursor composition each occupy two separate
but adjacent layers 40 and 50, element 10b of Fig. 3. In this manner, the spectral
sensitizer will sensitize only the photoinhibitor and not also the cobalt(III) complex
or the destabilizer material, so that photoinitiation of the inhibitor will not also
act to activate the image precursor composition. If the photoinhibitor does not inherently
produce a volatile acid capable of being readily transferred to the layer containing
the image precursor composition, for the inhibition step, the photoinhibitor layer
can optionally include sodium trifluoroacetate, to produce in the presence of the
nonvolatile acid generated by the photoinhibitor, trifluoroacetic acid which is sufficiently
volatile.
Examples
Examples 1-3 - Use of Organo-Metallic Destabilizer
[0069] Stock solution A was prepared by dissolving 265 mg of the cobalt complex, hexaamminecobalt(III)
trifluoroacetate, 535 mg of phthalaldehyde as amplifier and image-former and 30 mg
of 2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine as photoinhibitor in 2 g
of acetone. To this solution was added 10 g of a 20% solution of the binder poly(ethylene-co-
hexamethylene-1-methyl-2,4-benzenedisulfonamide) in 1:1 acetone/methylethylketone.
[0070] Solution B was prepared by dissolving 4 mg of the destabilizer ferrocene (dicyclopentadienyl
iron) in 6 g of acetone. Solution C was prepared by dissolving 4 mg of the destabilizer
1,1-dimethylferrocene in 6 g of acetone. Solution D was prepared by dissolving 10
mg of the destabilizer N,N-dimethylaniline chromium tricarbonyl in 6 g of acetone.
[0071] To 1.0 g of stock solution A was added O.lg of solution B to form the coating solution
for Example 1. This solution was then coated with a 100-micron doctor blade on a subbed
poly(ethylene terephthalate) support, dried, and overcoated with a 5% aqueous solution
of poly(acrylamido-co-N-vinyl-2-pyrrolidinone-co-2-acetoacetoxyethylmethacrylate using
a 50-micron doctor blade, and dried. After drying, the film was exposed through a
silver negative for about 8 seconds to the light from a 400 watt medium pressure mercury
arc lamp in an IBM Microcopier IID exposing apparatus and dye-developed by heating,
face up, for five seconds on a heated block at 160°C. A high density, positive image
resulted. Similar results were obtained when solutions C and D were substituted for
solution B to make the coating solutions for Examples 2 and 3.
Example 4 - 4-Phenvl Catechol as A Destabilizer Material Without Phthalaldehyde
[0072] 20 mg of [Co(NH
3)
6](CF'
3CO
2)
3, 7 mg of the destabilizer, 4-phenyl catechol and 16 mg of iodoform as the photoinhibitor
were dissolved in 700 mg of acetone. 1.4 g of a 15 percent solution of cellulose acetate
butyrate, as binder, in acetone were added and the resulting solution was coated with
a 100 micron doctor blade on a subbed poly(ethylene terephthalate) support. This film
was exposed for 8 seconds through a 0.3 log E silver step tablet in a copying apparatus
containing a 400-watt-medi-um pressure mercury arc lamp (commercially available as
a Micro Master Diazo T.M. Copier). The exposed film was placed in face-to-face contact
with a diazo-coupler recording element as an image forming layer (commercially available
from Eastman Kodak Company under the trade name Kodak Diazo Type M) and the sandwich
was passed twice through a set of rollers heated to 140°C at a speed of 12.7 cm per
minute. A positive bluish image of the step tablet was produced with minimum densities
of 0.07 and maximum densities of 0.5, when read using red light.
Examples 5-6 - Use of Sulfonamidophenyls and Naphthols as Destabilizer Materials
[0073] The following composition was prepared:

To identical 4.0 g portions of the above solution were added respective 12.0 mg portions
of the following sulfonamidophenol destabilizers:
Example 5
4-phenylsulfonamido-2,6-dichlorophenol
Example 6
4-phenylsulfonamido-2-methyl-l-naphthol
[0074] The resulting solutions were then coated with a 150-micron doctor blade on subbed
poly(ethylene terephthalate) support, dried and then overcoated with a 4.7% aqueous
solution of poly(acrylamido-CoN-vinyl-2 pyrrolidinone-Co-2-acetoacetoxy methacrylate
copolymer (50:45:5 by weight) containing 0.05% Surfactant lOG, a nonylphenoxyglycerol
coating aid, with a 50-micron doctor blade.
[0075] Samples of the dried coatings were then exposed for about two seconds through a 0.15
log E step tablet in an IBM Microcopier IID exposing apparatus. Processing for a 7.3
second contact time at 150-155°C in a Canon Kal-Developer Model 360 VC resulted in
positive images for each coating.
[0076] Further coating samples were similarly exposed and dye-developed for ten seconds,
face up, on a hot block. The neutral D-max obtained as a function of process temperature
follows:

Example 7 - Other Naphthol Destabilizer Materials
A solution was prepared by dissolving
[0077] 200 m
g of [Co(NH
3)
6] (CF

CO
2)
3, 400 mg of the amplifier and image-former phthalaldehyde, and 200 mg of 2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine
as photoinhibitor in 2 g of acetone. To this solution were added 8 g of a 20% solution
of the binder poly(ethylene-co-hexamethylene-l-methyl-2,4-benzenedisulfonamide) in
acetone.
[0078] In 2 g of this solution was dissolved 1 mg of the destabilizer, 4-methoxynaphthol.
This solution was coated with a 100 micron doctor-blade on subbed poly(ethylene terephthalate)support,
dried, and then overcoated with a 5% aqueous solution of the overcoat polymer of Example
1 using a 50 micron doctor blade. After drying, the film was exposed and dye-developed
in the manner described in Example 1, to give a neutral positive image with a D-max
of 2.7 and a D-min of 0.08.
Example 8 - A Pyrazolidone as a Destabilizer
Material
[0079] The following composition was prepared:

To a 3.8 g portion of this composition was added 6.5 mg of 4-hydroxy-methyl--4-methyl-1-phenyl-3-pyrazolidone.
[0080] The resulting solution was then coated with a 150-micron doctor blade on a subbed
poly-(ethylene terephthalate) support, and dried. The coating was overcoated with
a 5% aqueous solution of the overcoat polymer of Example 1 containing 0.05% Surfactant
lOG with a 50-micron doctor blade.
[0081] A sample of the dried coating was then exposed for about 16 seconds through a 0.15
log E step tablet to the light from a medium pressure mercury arc lamp in an IBM Microcopier
IID exposing apparatus and heat processed for a 5.5-second contact time at 150°C in
a Canon Kal-Developer, Model 360 VC. A positive image with neutral D-max of about
2.73 and a brownish D-min of 0.21 was obtained.
Example 9 - Another Pyrazolidone Destabilizer A solution was prepared by dissolving
[0082] 20
0 m
g of [Co(NH
3)
6 ](CF
3·CO
2)
3, 400 mg of phthalaldehyde (amplifier and image-former), and 200 mg of the photoinhibitor
2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine in 2 g cf acetone. To this solution
were added 8 g of a 20% solution of the binder poly(ethylene-co-hexamethylene-l-methyl-2,4-benzenedisulfonamide)
in acetone.
[0083] In 2 g of the above solution was dissolved 1 mg of 4,4-dimethyl-1-phenyl-3-pyrazolidone.
This solution was coated with a 4-mil doctor blade on subbed poly(ethylene terephthalate)
support, dried, and then overcoated with a 5% aqueous solution of the overcoat polymer
of Example 1 using a 50-micron doctor blade. After drying again, the film was exposed
through a silver negative for about 8 seconds in an IBM microcopier IID exposing apparatus
and heat-processed, face up, for five seconds on a 160°C hot block to give a neutral
positive image with a D-max of 3.0 and a D-min of 0.05.
Example 10 - Acids as Destabilizer Materials
[0084] An image precursor composition solution was prepared for Example 10 comprising 400
mg of [Co(NH
3)
6 7 (CF
3.CO
2)
3, 800 mg of phthalaldehyde as amplifier and image-former, 200 mg of N,N-bis(2-hydroxyethyl)
dodecanamide as destabilizer enhancer, and 40 mg of 2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine
as photoinhibitor in 20 gms of 20% poly(ethylene-co-l,4-cyclohexylenedimethylene-l-methyl-2,4-benzenedisulfonamide
(binder) in acetone.
[0085] To two grams of this solution was added 4 mg of phthalamic acid, and the solution
was then coated on subbed poly(ethylene terephthalate) with a 100-micron coating knife.
A 50-micron overcoat of the overcoat polymer of Example 1 (5% in water) was then applied
after drying. The resulting film was exposed for 8 seconds in an IBM Microcopier IID
exposing device through a 0.3 log E step tablet and heated for 5 seconds, face up,
on a 160°C hot block. A positive neutral image with a D-max/D-min ratio of 2.0/0.06
was produced.
Example 11
[0086] Example 10 was repeated except that 4 mg of the destabilizer, 2-carboxycyclohexylamide
was used in place of the phthalamic acid. A positive image was produced having D-max/D-min
ratio of 2.1/0.06.
Example 12 - A Urea as a Destabilizer Material
[0087] A solution of an image precursor composition was prepared by dissolving 266 mg of
[Co(NH
3)
6] (CF
3·CO
2)
3 and 534 mg phthalaldehyde as amplifier and image-former in 2 g of acetone and adding
to this 10 g of a 20% solution of the binder, poly(ethylene- co-1,4-cyclohexylenedimethylene-1-methyl-2,4-benzene-
disulfonamide) in acetone.
[0088] In 2 g of this solution, were dissolved 8 mg of iodoform as photoinhibitor and 5
mg of 1-(2-hydroxyphenyl)urea as destabilizer. This solution was coated with a 100-micron
doctor blade and overcoated with a 5% aqueous solution of the overcoat polymer of
Example 1 using a 50-micron doctor blade. The film was dried and exposed through a
silver negative for 8 seconds on a Microcopier IID and dye-developed by heating, face
up, for 5 seconds on a 160°C hot block to produce a neutral positive image with a
maximum density of 2.8.
Example 13
[0089] Example 12 was repeated except that the photoinhibitor iodoform was replaced with
1 mg of

The film was exposed through a silver negative for 7 seconds to a 650-watt incandescent
light source (commercially available under the trade name Nashua 120 Multi-Spectrum
Copier). When dye-developed by the process described in Example 10, a neutral positive
image with a maximum density of 2.3 was produced. Example 14 - Salts as Destabilizer
Materials
[0090] In 3.8 g of a 13.6% solution of the binder, poly(ethylene-co-1,4-cyclohexylenedimethylene-l-methyl-2,4-benzenedisulfonamide)
in acetone were dissolved
66.
4 mg of [Co(NH
3)
6 7 (CF
3·CO
2)
3, 120 mg of the image-former o-phthalaldehyde; 9.9 mg of the photoinhibitor, 2,4-bis(trichloromethyl)-6-(p-anisyl)-s-Triazine;
26 mg of N,N-bis(2-hydroxyethyl) dodecanamide as destabilizer enhancer; and 12 mg
of SF-1066 surfactant (from General Electric). To this solution was added 9.6 mg of
1-β-aminoethyl)-2-imidazolidione trichloroacetate as destabilizer and the resulting
solution was coated with a 150-micron doctor blade on subbed poly(ethylene terephthalate)
support. This coating was then overcoated with a 4.5% solution of the overcoat polymer
of Example 1 in water with 0.06% lOG surfactant coating aid using a 50-micron doctor
blade.
[0091] The dried coating was exposed for 2 seconds through a 0.15 log E step tablet using
a Micro Master Diazo T.M. Copier and dye-developed by heating, face up, in a 150°C
Canon Kal-Developer, Model 360 VC for 5.5 seconds. A brownish positive image having
a D-max of 0.98 and a D-min of 0.17 to blue light was obtained.
[0092] It is believed that the destabilizer underwent the following thermal decomposition
to generate an amine:

Examples 15 - 16
[0093] In Example 15, Example 14 was repeated except that the destabilizer material comprised
2-amino-2-thiazoline trichloroacetate. Example 16 was a repetition of Example 14 except
the destabilizer material was anilinium trichloroacetate. Both of these produced a
satisfactory positive image. Example 17 - Use of a Morpholine Precursor Destabilizer
Material
[0094] In 78 g of acetone were dissolved 15.9 g of the binder, poly(ethylene-co-1,4-cyclohexylenedimethylene-l-methyl-2,4-benzenedisulfonamide);
650 mg of N,N-bis(2-hydroxyethyl) dodecanamide as
destabilizer enhancer; 1.66 g of [Co(NH
3)
6] (CF
3·
C0
2)
3; 17 mg of 2,4-bis (trichloromethyl)-6-(p-methoxystyryl)-s-triazine as photoinhibitor;
250 mg of the photoinhibitor, 2,4-bis(trichloromethyl)-6- •-(p-anisyl)-s-triazine;
3.0 g of o-phthalaldehyde as amplifier and image-former; and 800 mg of SF-1066 surfactant
(General Electric). To 3.8 g of this solution were added 3.2 mg of the destabilizer,
3,3-bis(morphilino)oxindole. The resulting solution was coated with a 150-micron doctor
blade on subbed poly(ethylene terephthalate) support, dried, and subsequently overcoated
with a 4.5% solution of the overcoat polymer of Example 1 in water with 0.05% lOG
surfactant coating aid using a 50-micron doctor blade.
[0095] The dried coating was exposed for 8 seconds through a 0.15 log E silver step tablet
using the Micro Master Diazo T.M. Copier and dye developed by heating, face up, on
a 150°C hot block. A neutral positive image having a D-max of 2.56 and D-min of 0.06
was obtained.
Examples 18-27 - Aminimides as Destabilizer Materials
[0096] A solution of an image precursor composition was prepared as follows:

[0097] To 10.0 g samples of the preceding solution were added the aminimides of Table III.
A separate control was prepared using the destabilizer, 5.,5-diphenylhydantoin in
place of the aminimide.

[0098] After mixing the resulting solutions, handcoatings were made utilizing a 150-micron
wet laydown upon a transparent, subbed, poly(ethylene terephthalate( support). The
coatings were appropriately dried and then overcoated with a 50-micron wet laydown
of 4.5% aqueous solution of the overcoat polymer of Example 1 containing 0.6% 10G
surfactant and dried. Coating samples were sensitometrically exposed in an IBM Microcopier
IID exposing unit and dye-developed by heating, face up, for 5 to 10 seconds in a
150°C Canon Kalfile processor. All samples and the control developed black dye in
the non-image areas and remained clear in the exposed areas, and thus were positive-working.
Example 18 was 1.2 log E slower and 0.3 higher in neutral D-max than the control which
exhibited a D-max of 2.6.
[0099] It was further found that Example 18 gave a substantial improvement over the control
in processing, or development, latitude.
Examples 28-31 - Use of Triazole Destabilizer Materials
[0100] In 81.5 g of acetone were dissolved 11.1 g of poly(ethylene-co-l,4-cyclohexylenedimethylene-l-methyl-2,4-benzenedisulfonamide)
(binder), 748 mg of N,N-bis(2-hydroxyethyl)dodecanamide (destabilizer enhancer), 1.73
g of [Co(NH
3)
6 ](CF
3·CO
2)
3,
19.
6 mg of 2,4-bis(trichloromethyl)-6-(p-methoxystyryl)-s-triazine (photoinhibitor), 288
mg of 2,4-bis(trichloromethyl)-6-(p-anisyl)-s-triazine (photoinhibitor), 3.46 g of
o-phthalaldehyde (image-former) and 920 mg of SF-1066 surfactant (obtained from General
Electric).
Example 28
[0101] To 4.0 g of this solution were added 9.5 mg of the destabilizer 5-methyl-l(2)-N-(anilinocarbonyl)
benzotriazole, having the formula:

the anilinocarbonyl group being a thermally releasable blocking group.
[0102] The resulting solution was coated with a 150-micron doctor blade on a subbed poly(ethylene
terephthalate) support, dried and then overcoated with a 4.7% solution of the overcoat
polymer of Example 1 in water containing 0.05% lOG surfactant coating aid, using a
50-micron doctor blade.
[0103] The dried coating was then exposed for 2 seconds through a 0.15 log E silver step
tablet using a Micro Master Diazo T.M. Copier and dye-developed by heating, face up,
on a 160°C hot block. A brownish, positive image having a D-max of 1.30 and D-min
of 0.58 to blue light was obtained.
[0104] Examples 29-31 were the same as Example 28, with approximately the same results,
except that the destabilizer materials were:

Example 32 - Thiolate Precursor Destabilizer Material
[0105] 8.2 mg of 2-methyl-2-¡2-pyridY17-5-chloro- benzothiazoline (destabilizer); 24.7 mg
of N,N-bis-(2-hydroxyethyl)-dodecanamide (destabilizer enhancer); 63.1 mg of [Co(NH
3)
6] (CF
3.C
02)
3; 0.7 m
g of 2,4-bis(trichloromethyl)-6-[p-methoxystyryl]-s-triazine (photoinhibitor); 9.5
mg of 2,4-bis(trichloromethyl)-6-[p-anisyl]-s-triazine (photoinhibitor); 114.4 mg
of phthalaldehyde (image-former); and 30.4 mg of SF-1066 surfactant were added to
3.6 g of 17% poly(ethylene-co-l,4-cyclohexylene-dimethylene-l-methyl-2,4-benzenedisulfonamide)
(binder) in acetone. This solution was coated with a 150-micron doctor blade on subbed
poly(ethylene terephthalate) support and dried. This image precursor composition layer
was then overcoated with a 5% solution of poly(acrylamide-co-N-vinyl-2-pyrollidone-co-2-acetoacetoxyethylmethacrylate)
in water with 0.05% surfactant lOG coating aid using a 50-micron doctor blade and
dried. A sample of the film coating was exposed through a silver negative for 8 seconds
on an IBM Microcopier IID device and dye-developed by heating in a 155°C Canon Kal-developer,
model 360 VC for 5.5 seconds. A black, positive image with a neutral D-min of 0.12
and a D-max of 3.2 was produced.
Examples 33 - 35
[0106] Example 32 was repeated except that the destabilizer material was, respectively,
2-methyl-2-carboxamidothiazolidine, 2-methyl-2-[2-pyridyl]benzo- thiazoline, and 2-methyl-2-L4-nitropheny17benzothia-
zoline. When tested at equivalent chemical levels and similar exposure and processing
conditions, these materials also yielded satisfactory results.
Example 36 - Use of a Blocked Mercaptotetrazole as a Destabilizer Material
[0107] 0.037 moles of 1-phenyl-[3-(4-toluenesulfonyl)propionyloxy7-5 mercaptotetrazole(See
Table IV), 29.9 mg of N,N-bis(2-hydroxyethyl) dodecanamide as
destabilizer enhancer, 69.0 mg of [Co(NH
3)
6] CF
3· CO
2)
3, 0.8 mg of the photoinhibitor 2,4-bis(trichloromethyl)-6-[p-methoxystyryl]-s-triazine,
11.5 mg of the photoinhibitor 2,4-bis(trichloromethyl)-6-¿
-p-anisyl7-s-triazine, 138.5 mg of phthalaldehyde as amplifier and dye-former, and
36.8 mg of SF-1066 surfactant were added to 3.7 g of 12% poly(ethylene- co-1,4-cyclohexylene-dimethylene-1-methyl-2,4-benzenedisulfonamide)(binder)
in acetone. This solution was coated with a 150-micron doctor blade on a subbed poly(ethylene
terephthalate) support and dried. This basecoat was then overcoated with a 4.7% solution
of the overcoat polymer of Example 1 in water with a 0.05% surfactant lOG coating
aid using a 50-micron doctor blade and dried. A sample of the film coating was exposed
through a silver negative for 2 seconds on an IBM Microcopier IID device and dye-developed
by heating on a 170°C hot block for 10 seconds, support side down. A positive image
was produced with a D-min of 0.19 and a D-max of 0.90.
Examples 37 - 41
[0108] Example 36 was repeated except that equivalent amounts of the blocked mercaptotetrazoles
listed in Table IV were substituted for that of Example 36. When similarly exposed
and processed, the elements of Examples 37-41 produced comparable results.

Example 42 - Use of a Cyclic Imide as the Destabilizer Material
[0109] In 2 g of a 20% solution of poly(ethylene-co-l,4-cyclohexylene-dimethylene-l-methyl-2,4-benzenedisul-
fonamide) (binder) in 95:5 acetone:H
20 were dissolved 40 m
g of [Co(NH
3)
6](CF
3·CO
2)
3, 48 mg o-phthalaldehyde (amplifier and image-former), 5 mg of succinimide as destabilizer,
and 30 mg of iodoform as photoinhibitor. This solution was coated with a 100-micron
doctor blade on a subbed poly(ethylene terephthalate) support. This film was exposed
through a silver negative for 0.5 seconds on an IBM microcopier IID device and dye-developed
by heating for 10 seconds face-up on a 145°C hot block. A black positive image with
a neutral density D-max of 1.4 and a D-min of 0.04 was formed.
Example 43
[0110] In 10 gms of a 20% solution of the binder, poly(ethylene-co-1,4-cyclohexylene-dimethylene-1-methyl-2,4-benzenedisulfonamide)
in acetone were dissolved 200 mg of [Co(NH
3)
6 7 (CF
3·CO
2)
3,
400 mg phthalaldehyde (image-former), 25 mg 5,5-diphenylhydantoin (destabilizer) and 20
mg 2,6-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine (photoinhibitor). This solution
was coated as in Example 42 and aged for one week to allow sensitometry to stabilize.
A sample was exposed through a silver negative for four seconds in the IBM Micropier
IID device. Ten seconds dye-development by heating on a 140°C hot block produced a
black positive image with a D-max of 2.05 and a D-min of 0.05.
Example 44 - Use of a Barbiturate as a Destabilizer Material
[0111] A stock solution was prepared by adding 798 mg of [Co(NH
3)
6 _7 (CF
3·CO
2)
3, 1.6 g of phthalaldehyde image-former, and 60 mg of 2,4-bis(trichloromethyl)-6-p-anisyl-s-triazine
photoinhibitor to 30 g of 20% solution of poly(ethylene-co-1,4-cyclohexylenedimethylene-1-methyl-2,4-benzenedisulfonamide)
in acetone.
[0112] In 1 g of acetone were dissolved 3 mg of 5-n-butylbarbituric acid. 0.1 g of this
solution was then added to 1.0 g of the stock solution, coated, overcoated, exposed,
and processed as in Example 7 to give a positive image with a D-max of 3.0 and a D-min
of 0.1.
ExamDle 45 - Use of a Quinone Photoreductant as a Destabilizer Material
[0113] 75
mg of [Co(NH
3)
6] (CF
3·CO
2)
3 and 60 m
g of 2-(N-ethyl-N-benzylamino)-3-chloro-1,4-naphthoquinone, a photoreductant, were
dissolved in 1.7 g of 2-methoxyethanol. To this solution, 3.4 g of a 15 percent solution
of cellulose acetate butyrate in acetone was added to form a stock solution.
[0114] A quantity of 40 mg of iodoform was dissolved in 1 g of chloroform. To this solution,
a quantity of 2 g of the above stock solution was added. The resulting solution was
coated with a 100-micron doctor blade on a subbed poly(ethylene terephthalate) support.
[0115] A sample of this film was exposed for 2 minutes through a silver test object on a
U.V. exposing device, available commercially as a Canon Kalfile Printer 340VC. This
exposure imagewise generated inhibitor. The film was then given an overall 30- second
exposure to tungsten light using a Hashua 120 Multi-Spectrum Copier to photogenerate
reductant. The exposed film was placed in face-to-face contact with a diazo recording
element (commercially available under the trade name Kodak Diazo Type M) and the sandwich
was passed twice at 76.2 cm per minute through a set of rollers heated to a temperature
of 100°C. A positive image was developed with a maximum density of 1.0 and a minimum
density of 0.07 measured in red light. (The heating step was used to increase the
dye-development reaction initiated by the overall exposure.)
Examples 46-47 - Using a Quinone Photoreductant to be Either Positive- or Negative-Working
[0116] In 1 g of dioxane were dissolved 120 mg of iodoform (photoinhibitor) and 25 mg of
the destabilizer 2-dibenzylamino-3-chloro-1,4-naphthoquinone. To this solution was
added a second solution consisting of 120 mg of [Co(NH
3)
6 7 (C
F3.C
02)
3 and 166 mg phthalaldehyde (image-former) in a 20% solution of the binder poly(ethylene-co-1,4-cyclohexylenedimethylene-l-methyl-2,4-benzenedisulfonamide)
in 95:5 by volume acetone:H
20. This solution was coated with a 100-micron doctor blade on subbed poly(ethylene
terephthalate) support and overcoated with a 10% solution of (copolyester 1,1,3-trimethyl-5-carboxy-3-(p-carboxyphenyl)indan
bisphenol A) in toluene.
[0117] A dried coating was exposed to visible light for 0.5 seconds on an IBM Microcopier
IID device through a silver negative and a Wratten 2A filter which removes ultraviolet
radiation. Upon heating for 15 seconds face-up on a 140°C hot block, a dense black
negative image was formed.
[0118] Example 47 comprised a repetition of Example 46, except that the element was exposed
for 6 seconds on an IBM Microcopier IID through a silver negative and a Wratten 34
filter which passes ultraviolet radiation, followed by a 0.5 seconds dye-development
exposure through a Wratten 2A filter. Fifteen seconds of heating face-up on a 140°C
hot block developed a dense positive image. Comparative Examples (C.E.)
C.E.No. 1
[0119] Example 13 was repeated except that anilinium methenebisulfonyl acetate was tested
as a potential destabilizer material. This was found to be incompatible inasmuch as
it caused precipitation of the cobalt(III) complex.
C.E. Nos. 2 and 3
[0120] Example 11 was repeated except that the urea of Example 11 was replaced by, respectively,

or

[0121] No image discrimination was found in either example, demonstrating that these compounds
are not acceptable destabilizer materials.