FIELD OF THE INVENTION
[0001] The present invention relates to a thermal recording material or heat developable
light-sensitive material. The invention also relates to a method of image formation
using a thermal recording material or heat developable light-sensitive material.
BACKGROUND OF THE INVENTION
[0002] Traditionally, various means have been used to obtain visible images, including ink
jets, electrophotography, thermal recording materials and silver halide light-sensitive
materials.
[0003] Of these means, thermal recording materials have advantages, such as easy operation
and maintenance, feasibility for reduction in equipment size and cost and low running
cost. Particularly, thermal transfer printing has recently been the subject of many
research and development activities as can satisfy the requirements for both image
quality and cost, in which a thermal transfer ribbon, comprising a support and a layer
of dispersion of dye or pigment in binder coated thereon, and recording paper are
superposed and heat according to the image information is applied to the back face
of the thermal transfer ribbon via a thermal head to record images. The thermal imaging
method using a laser beam has also recently been investigated, which is described
in an special issue "Imaging Part 2, - Current Hard Copy Printer Technology" of "Shashin
Kogyo", pp. 63-113 (published by Shashin Kogyo Shuppansha on July 20, 1988), for instance.
However, much remains unsatisfactory as to image properties, and further improvements
are desired.
[0004] On the other hand, silver halide photographic light-sensitive materials have a handling
problem of the necessity for use of liquids such as a developer, though they surpass
other image recording materials with respect to image quality. As a means of solving
this problem, what is called the heat development method has been developed, in which
exposure is followed by heat development to form images. Details of such a heat development
method are given in the proceedings of the 17th symposium of the Society of Photographic
Science and Technology of Japan titled "Discussion on Heat Developable Silver Salt
Recording System" (May 1987) . In these heat development methods, silver or dye images
are formed by heat treatment and, if necessary, pressure treatment, after imagewise
exposure of a heat developable light-sensitive material having a light-sensitive silver
halide, a binder and a reducing agent on the support. Particularly in thermal transfer
type heat developable recording materials, clearer dye images can be obtained by transferring
the formed dye image to an image receiving material. Although heat developable light-sensitive
materials offer high image quality similarly to silver halide light-sensitive materials,
the image quality level is lower than that obtained with conventional liquid processable
light-sensitive materials. With this background, further improvements are desired,
and development of positive-type heat developable light-sensitive materials is desired.
[0005] 1,3-sulfur-nitrogen-containing compounds are known to undergo cleavage reaction by
the action of silver ion. Attempts have been made to utilize this reaction for imagewise
release of reagents in photographic processing. For example, Japanese Patent Examined
Publication No. 7576/1980 describes a technology in which a 1,3-sulfur-nitrogen-containing
compound is cleaved according to the imagewise distribution of silver ion to release
a photographically useful group (hereinafter referred to as PUG), with mention of
its applicability to so-called instant photographic materials. Such photographically
useful groups include image forming dyes, their intermediates, antifogging agents
and gelatin hardeners. On the other hand, silver ions are supplied in the form of
a soluble silver complex ions by the action of a silver halide solvent. An imagewise
distribution of silver ions occurs in the unexposed portion.
[0006] Japanese Patent O.P.I. Publication No. 180548/1984 discloses a method by which a
mobile dye is imagewise formed by heating a 1,3-sulfur-nitrogen-containing compound
as a dye donator for heat developing type light-sensitive material preferably in the
presence of base.
[0007] In Examples thereof, however, it was merely shown that images are obtained by transferring
image dyes produceded by heat development to image-receiving materials in the presence
of water.
[0008] In addition, the presence of base or base precursor to the light-sensitive material
results in local formation of mobile dye during storage, which in turn poses a problem
of image quality deterioration such as increased fogging.
[0009] Also, the heat developing type light-sensitive material containing a base or base
precursor has a drawback of tendency toward maximum density reduction, though it permits
fogging reduction in the desired dye image by acceleration of silver development.
[0010] Particularly recording materials incorporating a hydrophilic binder are normally
used after being subjected to aging at a given temperature for a given period to increase
the degree of hardening. This aging is carried out at temperatures of normally 25
to 50°C, preferably 30 to 45°C for periods of normally 12 hours to 1 month, preferably
1 day to 2 weeks. In the light-sensitive material containing a 1,3-sulfur-nitrogen-containing
compound and a base or base precursor, a mobile dye forming reaction can take place
even during this storage for improvement in the degree of hardening, which leads to
a considerable tendency toward image quality deterioration such as increased fogging.
SUMMARY OF THE INVENTION
[0011] It is an object of the present invention to provide a new thermal recording material
or new heat-developable light-sensitive material which works on the basis of chemical
reaction of silver ion and 1,3-sulfur-nitrogen-containing compound.
[0012] It is another object of the present invention to provide a thermal recording material
or heat developable light-sensitive material which offers improved image quality,
particularly improvement in image discrimination.
[0013] It is still another object of the present invention to provide a new positive-type
heat-developable light-sensitive material.
[0014] It is yet another object of the present invention to provide a heat-sensitive recording
material or heat developing type light-sensitive material which undergoes little deterioration
in image quality during long-term storage.
[0015] The present inventors found that reaction takes place between an organic silver salt
and a 1,3-sulfur-nitrogen-containing compound in the presence of a thermal solvent,
and substantially in the absence of water and base, and that the use of this reaction
makes it possible to obtain a recording material accomplishing the objects described
above.
[0016] Accordingly, the objects described above have been accomplished by a recording material
wherein at least a 1,3-sulfur-nitrogen-containing compound capable of being cleaved
in the presence of silver ions or water-soluble silver complex salt, an organic silver
salt and a thermal solvent are coated on a support.
[0017] The recording material is capable of forming visible images upon imagewise heating
substantially in the absence of water and base. This recording material is embodied
as a heat developable light-sensitive material by adding a light-sensitive silver
halide. When the recording material is embodied as a heat developable light-sensitive
material, images can be formed by subjecting it to imagewise exposure, after which
or simultaneously with which it is subjected to heating substantially in the absence
of water and base.
[0018] The present invention is hereinafter described in detail.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The 1,3-sulfur-nitrogen-containing compound of the present invention is preferably
represented by the following formula 1.

wherein R₁ and R₂ independently represent a hydrogen atom, aliphatic group, aromatic
group or heterocyclic group. R₃ represents a hydrogen atom, aliphatic group, aromatic
group, heterocyclic group or acyl group. Z represents a group of non-metallic atoms
necessary to form the ring, which ring may have a substituent thereon. Z may cooperate
with S-C-N to form a condensed ring. At least one of R₁, R₂, R₃ and the substituent
on the ring formed by Z is a photographically useful group (PUG) or precursor thereof
released upon reaction of the compound of Formula 1 with a silver ion or silver complex
ion under heating. Either of R₁ and R₂ is preferably other than a hydrogen atom, and
R₃ is preferably other than a hydrogen atom.
[0020] It is therefore possible to release the desired compound by choosing an appropriate
substituent in the compound of Formula 1 and heating in the presence of an organic
silver salt. Also, the immobility (diffusion resistance) and solubility of the compound
of Formula 1 can be regulated by choosing an appropriate substituent.
[0021] Typical examples of the substituent include carboxyl, sulfo, nitro, hydroxy, halogens
such as chlorine, bromine and cyanogen, and hydrocarbon residues including aliphatic,
alicyclic and aromatic groups as well as those exemplified for Formulas 1 above. This
substituent may have an ethylenic or acetylenic group, and its carbon chain may be
interrupted by a hetero atom or hetero atom-containing group such as S, O, N, SO or
NH. This substituent may also contain a substituent such as phenylalkyl, alkyl ether,
aryl ether, carboalkoxy, carboxyl, hydroxy, sulfo, halogen, cyano, nitro or alkylamino.
[0022] Other appropriate groups include substituted or unsubstituted alkyl groups such as
methyl, ethyl, octyl and dodecyl, substituted or unsubstituted cycloalkyl groups such
as cyclohexyl, cyclopentyl and cyclooctyl, substituted or unsubstituted alkenyl groups
such as vinyl, allyl, butenyl, decenyl, octadienyl and hexatrienyl, substituted or
unsubstituted cycloalkenyl groups such as cyclopentenyl, cycloheptenyl and cyclohexadienyl,
substituted or unsubstituted alkinyl groups such as ethynyl, hexynyl and octynyl,
substituted or unsubstituted aryl groups such as phenyl, tolyl, benzyl and naphthyl,
substituted or unsubstituted heterocyclic groups such as those having a 4-, 5-, or
6-membered ring and O, N or S and derivatives thereof such as pyrrole, pyrazole, oxazole,
thiazole, imidazole, pyrimidine, piperidine, piperazine, thiophene, pyrrolidine and
azetidine.
[0023] 1,3-sulfur-nitrogen-containing compounds which are used in image recording materials
are preferably cyclic sulfur-nitrogen-containing compounds having S and N atoms in
their ring, specifically thiazolidine and benzothiazolidine. These compounds undergo
cleavage reaction at a given rate upon heating in the presence of an organic silver
to release a PUG, particularly a dye.
[0024] These compounds can be used under alkaline to acidic conditions and preferably under
neutral to acidic conditions.
[0025] With respect to the 1,3-sulfur-nitrogen-containing compound of the present invention,
the photographically useful group (PUG) or precursor thereof is preferably substituted
on the carbon atom bound to the sulfur and nitrogen atoms. In other words, one of
R₁ and R₂ or both in the compound of Formula 1 are preferably PUG. Examples of PUG
include dyes, developing inhibitors, developing accelerators, fogging agents, developing
agents, hardeners, couplers, toning agents and brightening agents.
[0026] In the present invention, the substances preferably used as PUG are dyes, developing
inhibitors and developing accelerators, with preference given to dyes.
[0027] When the dye moiety substituted as R₁ or R₂ in the compound of Formula 1 is a transferable
dye, R₃ and one or more groups substituted on the ring Z are preferably ballast groups
which substantially immobilize the compound of Formula 1.
[0028] The balast groups include ordinarily those having at least 8 carbon atoms and preferably
substituted or unsubstituted alkyl groups having 8 to 40 carbon atoms.
[0029] Here, the balast group may be a polymer residual group. In this case, the average
molecular weight of the compound represented by Formula 1 is preferably not less than
10,000.
[0030] Among the compounds represented by formula 1, preferable compounds are thiazolidine
derivatives or benzothiazolidine derivatives and especially preferable ones are thiazolidine
derivatives.
[0031] As the transferable dye released from the compounds represented by Formula 1, any
conventional dyes known by those skilled in the art including azo, azomethine, indoaniline,
oxonol, cyanine, thiazole, anthraquinone, ditriphenylmethane and triphenylmethane
dyes can be used.
[0032] It is possible to cause releasing dye precursors in place of dyes.
[0033] "Dye precursor" is a compound producing dye molecules by reacting with other molecules
or ions, or by heating, after being released.
[0035] Examples of organic silver salts which can be used for the present invention include
the silver salts of long-chain aliphatic carboxylic acid and silver salts of carboxylic
acid having a heterocyclic ring, such as silver laurate, silver myrystate, silver
palmitate, silver stearate, silver arachidonate, silver behenate and silver α-(1-phenyltetrazolethio)acetate,
and the silver salts of aromatic carboxylic acid such as silver benzoate and silver
phthalate, described in Japanese Patent Examined Publication No. 4921/1968, Japanese
Patent O.P.I. Publication Nos. 52626/1974, 141222/1977, 36224/1978 and 37610/1978,
and US Patent Nos. 3,330,633, 3,794,496 and 4,105,451, and the silver salts of compounds
having an imino group described in Japanese Patent Examined Publication Nos. 26582/1969,
12700/1970, 18416/1970 and 22185/1970, Japanese Patent O.P.I. Publication Nos. 137321/1977,
118638/1983 and 118639/1983, and US Patent No. 4,123,274.
[0036] Examples of silver salts having an imino group include benzotriazole silver, which
may be substituted or not. Typical examples of substituted benzotriazole silver include
alkyl-substituted benzotriazole silver, alkylamidobenzotriazole silver, alkylsulfamoylbenzotriazole
silver, halogen-substituted benzotriazole silver salts, alkoxybenzotriazole silver,
5-nitrobenzotriazole silver, 5-aminobenzotriazole silver, 4-hydroxybenzotriazole silver,
5-carboxybenzotriazole silver, 4-sulfobenzotriazole silver and 5-sulfobenzotriazole
silver.
[0037] Examples of other silver salts having an imino group include imidazole silver, benzimidazole
silver, 2-methylbenzimidazole silver, 6-nitrobenzimidazole silver, pyrazole silver,
urazol silver, 1,2,4-triazole silver, 1H-tetrazole silver, 3-amino-5-benzylthio-1,2,4-triazole
silver, saccharin silver, phthalazinone silver and phthalimide silver, and silver
salts of mercapto compound such as 2-mercaptobenzoxazole silver, mercaptooxadiazole
silver, 2-mercaptobenzothiazole silver, 2-mercaptobenzimidazole silver, 3-mercapto-4-phenyl-1,2,4-triazole
silver, 1-phenyl-5-mercaptotetrazole silver, 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene
silver and 5-methyl-7-hydroxy-1,2,2,4,6-pentazaindene silver.
[0038] Examples also include the silver salts of carboxylic acid which decarboxylate at
high temperatures described in Japanese Patent O.P.I. Publication No. 211454/1985
and the silver salts of acetylene derivative described in Japanese Patent O.P.I. Publication
Nos. 226744/1986 and 231542/1986.
[0039] Silver complex compounds having a stability constant of 4.5 to 10.0 as described
in Japanese Patent O.P.I. Publication No. 31728/1977 and silver salts of imidazolinethione
as described in US Patent No. 4,168,980 can also be used.
[0040] Of the organic silver salts mentioned above, silver salts of compounds having an
imino group, particularly silver salts of benzotriazole derivatives are preferred,
with more preference given to silver salts of benzotriazole, 5-methylbenzotriazole
and derivatives thereof, sulfobenzotriazole and N-alkylsulfamoylbenzotriazole.
[0041] Other known organic silver salts can be used in the recording material of the present
invention.
[0042] The organic silver salts described above may be used singly or in combination. They
may be used as such after removing soluble salts in an aqueous solution of hydrophilic
colloid such as gelatin, or may be used as fine grains of solid obtained by mechanical
pulverization and dispersion of the organic silver salt after its isolation. The amount
of organic silver salt used is normally 0.01 to 20 g, preferably 0.1 to 5 g per m²
of recording material.
[0043] For the purpose of acceleration of the reaction of 1,3-sulfur-nitrogen-containing
compound and organic silver salt taking place upon heating, promotion of the transfer
of the dye formed and other purposes, it is preferable to add a thermal solvent (hot
melting substance) to the recording material of the present invention. The thermal
solvent is a compound which liquifies upon heating and acts to accelerate the image
formation. It is preferably in a solid state at normal temperature, and its melting
point is preferably 70 to 170°C. For use for the present invention, the thermal solvent
preferably has the following nature.
[0044] Occurs as a white solid at normal temperature and becomes colorless and transparent
upon melting.
[0045] The heating volatility is minimum.
[0046] Examples of thermal solvents which can be used for the present invention include
the compounds described in US Patent Nos. 3,347,675, 3,438,776, 3,666,477 and 3,667,959,
RD No. 17643 and Japanese Patent O.P.I. Publication Nos. 19525/1976, 24829/1978, 60223/1978,
118640/1983, 198038/1983, 68730/1984, 84236/1984, 229556/1984, 14241/1985, 191251/1985,
232547/1985, 52643/1986, 42153/1987, 44737/1987, 78554/1987, 136645/1987, 139545/1987,
53548/1988, 161446/1988, 224751/1989, 227150/1989, 863/1990, 120739/1990 and 123354/1990.
[0047] Thermal solvents which are preferably used in the recording material of the present
invention are described below.
[0048] The thermal solvent preferably has an i/o value of not less than 0.5 and not more
than 4. Here, the i/o value indicates the degree of organicity or inorganicity of
compounds, calculated by the method described in "Kagaku no Ryoiki", vol. 11, pp.
719-725 (1957), published by Nankodo Shuppan.
[0049] Compounds which are more preferably used as thermal solvents for the present invention
are represented by the following formula 2.

wherein hyd represents a group whose π value is -0.9 to -1.9 (π value is a parameter
indicating hydrophobicity; the values used were obtained from "Kagaku no Ryoiki",
supple. No. 122, "Yakubutsu no Kozo Kassei Sokan" (Nankodo), pp. 96-103.
[0050] Examples of groups preferred for hyd include -NHCOCH₃, -CH₂OH, -NHSO₂CH₃, -CONHCH₃,
-NHCONH₂, -CONH₂, -NHCSNH₂, -SO₂CH₃, -CH₂CONH₂, -SO₂NH₂; -OCONH₂, -OCH₂CONH₂ and -N(SO₂CH₃)₂.
[0051] R₄ through R₈ in Formula 2 can be selected according to the hyd group so that the
i/o value of the compound falls in the range from 1 to 3. Examples of R₄ through R₈
include hydrogen atoms, and alkyl groups, aryl groups, alkoxy groups, aryloxy groups,
alkoxycarbonyl groups, acyloxy groups and halogen atoms which may have various substituents.
[0052] Of the compounds represented by Formula 2, thermal solvents which are solid at room
temperature and sparingly water-soluble are preferred.
[0054] When added to a recording material comprising a plurality of layers, these thermal
solvents may be added to any structural layer. The thermal solvent for the present
invention is added at ratios of preferably 10 to 500% by weight, more preferably 20
to 250% by weight of the total amount of binder in the recording material. The thermal
solvent of the present invention is added preferably as a suspension of fine particles
in an aqueous colloidal medium using a ball mill, sand mill or another means.
[0055] The thermal solvents for the present invention may be used in combination of two
or more kinds.
[0056] The recording material of the present invention is embodied by coating on a support
a composition comprising a 1,3-sulfur-nitrogen-containing compound, an organic silver
salt and a thermal solvent along with a binder.
[0057] When using the recording material of the present invention as a thermal recording
material, the desired compound can be formed by heating the coating product using
a thermal head or a condensed laser beam or the like to cause reaction between a 1,3-sulfur-nitrogen-containing
compound above and silver ion at the heated portion.
[0058] Imagewise heating makes imagewise formation of the desired compound possible. For
example, introducing a dye or a group capable of becoming a dye intermediate to a
substituent makes imagewise distribution of the dye. In short, a dye image can be
formed, which has a potential for application to a thermal image forming material.
[0059] The recording material of the present invention can be embodied as a thermal transfer
recording material when the 1,3-sulfur-nitrogen-containing compound of the present
invention is a non-diffusible dye and the product of reaction with organic silver
salt is a diffusible dye.
[0060] The thermal transfer recording material of the present invention comprises a support
and a thermal transfer layer formed thereon which contains the composition of the
present invention. The 1,3-sulfur-nitrogen-containing compound content in the thermal
transfer layer is preferably 0.05 to 10 g per m² of support.
[0061] The thermal transfer layer can be formed by dissolving in a solvent one or more kinds
of the 1,3-sulfur-nitrogen-containing compound of the present invention along with
a binder or dispersing them in a dispersant in the form of fine grains to yield an
ink solution for thermal transfer layer formation, and coating and drying the ink
on the support. The dry thickness of the thermal transfer layer is preferably 0.1
to 10 µm.
[0062] Examples of preferred binders include solvent-soluble polymers such as acrylic resin,
methacrylic resin, polystyrene, polycarbonate, polysulfone, polyether sulfone, polyvinylbutyral,
polyvinylacetal, nitrocellulose and ethyl cellulose. These binders may be used singly
or in combination, and may be used in dispersion in latex as well as in solution in
organic solvent.
[0063] The amount of binder used is preferably 0.1 to 20 g per m² of support. Examples of
such organic solvents include alcohols such as ethanol and propanol, cellosolves such
as methyl cellosolve, aromatic compounds such as toluene and xylene, esters such as
acetates, ketones such as acetone and methyl ethyl ketone and ethers such as tetrahydrofuran
and dioxane.
[0064] Any material can be used for the support, as long as it is dimensionally stable and
endures heating by thermal head etc. upon recording. Examples of preferred materials
include thin papers such as condenser paper and glassine paper, and heat stable plastic
films such as those of polyethylene terephthalate, polyamide and polycarbonate. The
thickness of the support is preferably 2 to 30 µm, and the support preferably has
a subbing layer comprising a polymer selected for the purpose of improving the binder
adhesion and preventing dye transfer and deposition on the support. Moreover, the
back face (the side opposite to the thermal transfer layer) of the support may have
a slipping layer for the prevention of head cohesion to the support.
[0065] For applying the thermal transfer recording material relating to the present invention
to a thermal recording material permitting full-color image recording, it is preferable
to repeatedly coat on a support a total of three layers, namely a magenta thermal
transfer layer containing a magenta image forming thermally-diffusible dye, a cyan
thermal transfer layer containing a cyan image forming thermally-diffusible dye and
a yellow thermal transfer layer containing a yellow image forming thermally-diffusible
dye. A total of four layers, namely a thermal transfer layer containing a black image
forming substance and the three layers described above may be repeatedly coated on
the same surface.
[0066] On the other hand, the recording material of the present invention is embodied as
a light-sensitive thermal recording material by adding a light-sensitive-containing
material to a composition comprising a 1,3-sulfur-nitrogen-containing compound, an
organic silver salt and a thermal solvent and coating the mixture along with a binder
on the support. In such a material, image recording is achieved optically, wherein
images are formed upon uniform heating. This type of materials are referred to as
heat developable light-sensitive materials.
[0067] The heat developable light-sensitive material relating to the present invention is
described below.
[0068] In the heat developable light-sensitive material relating to the present invention,
a light-sensitive silver halide is used as the light-sensitive material.
[0069] The organic silver salt described above is reduced with a reducing agent as described
below under heating conditions. This reaction is accelerated by so-called latent images
formed on the exposed fine grains of silver halide. In other words, in the heat developable
light-sensitive material, the organic silver salt undergoes reduction in the exposed
portion. Taking place concurrently with this reaction, the reaction of 1,3-sulfur-nitrogen-containing
compound and organic silver salt is suppressed in the exposed portion.
[0070] Consequently, it is possible to cause the reaction of 1,3-sulfur-nitrogen-containing
compound and organic silver salt selectively in the unexposed portion, i.e., reverse-imagewise
formation of the desired compound is possible.
[0071] This principle is applicable to the formation of positive images, for instance.
[0072] When embodying the present invention as a transfer type heat developable light-sensitive
material, for instance, dye transfer occurs in the unexposed portion provided that
a dye or a group capable of becoming a dye intermediate is introduced to the substituent
for the 1,3-sulfur-nitrogen-containing compound and made non-diffusible and allowed
to form a diffusible dye or dye intermediate after reaction with organic silver salt,
i.e., positive images can be formed.
[0073] The compound released in the reverse-imagewise manner is not necessarily a dye; it
may be any PUG, such as a developing inhibitor, fogging agent, developing agent, hardener,
developing accelerator or brightening agent for controlling the image formed.
[0074] Examples of binders which can be used in the heat developable type light-sensitive
material of the present invention include the binders described in Japanese Patent
O.P.I. Publication No. 863/1990, line 14, upper right column, through line 10, lower
left column, page 10, including preferable combinations thereof. More preference is
given to gelatin, polyvinyl pyrrolidone and combinations thereof.
[0075] With respect to the silver halide reducing agent, dye providing substance and additive,
binder support, image receiving material, constituting the heat developable light-sensitive
material, exposure and development, any material or means can be used. Examples thereof
are given in Japanese Patent Application Nos. 256079/1989 (pp. 14-47) and 158931/1990
(pp. 13-41), filed by the present applicants.
[0076] Any known conventional light-sensitive silver halide can be used in the heat developable
light-sensitive material of the present invention. Examples of such light-sensitive
silver halides include silver chloride, silver bromide, silver iodobromide, silver
chlorobromide and silver chloroiodobromide.
[0077] The reducing agent used in the heat developable light-sensitive material of the present
invention is selected as appropriate out of the known conventional reducing agents
in use for heat developable light-sensitive materials according to the developing
mechanism and dye formation or release mechanism. The reducing agent referred here
includes reducing agent precursors which release a reducing agent upon heat development.
[0078] The heat developable light-sensitive material of the present invention is used as
a black-and-white or color light-sensitive material. When it is used as a color light-sensitive
material, a dye-providing material is used.
[0079] Although it is of course possible to use the 1,3-sulfur-nitrogen-containing compound
of the present invention as a dye-providing material as stated above, it may be used
in combination with other dye-providing materials. The 1,3-sulfur-nitrogen-containing
compound may be designed to release a photographically useful compound other than
a dye and may be used to form a color image in the presence of other dye-providing
materials.
[0080] Examples of such dye-providing materials include the diffusible dye forming couplers
described in Japanese Patent O.P.I. Publication Nos. 44737/1987, 129852/1987 and 169158/1987
and Japanese Patent Application No. 200859/1989, the leuko dye described in Japanese
Patent O.P.I. Publication No. 88254/1986 and the azo dyes used for the heat developable
dye bleaching method described in US Patent No. 4,235,957. It is preferable to use
a dye-providing material which forms or releases a diffusible dye, with more preference
given to a compound which forms a diffusible dye upon coupling reaction.
[0081] In addition to the substances described above, the heat developable light-sensitive
material of the present invention may incorporate various additives as necessary.
[0082] The heat developable light-sensitive material of the present invention contains (a)
a 1,3-sulfur-nitrogen-containing compound, (b) an organic silver salt, (c) a reducing
agent, and (d) a light-sensitive silver halide. When it is used as a color light-sensitive
material, it further contains (e) a dye-providing material, which may be identical
to (a) or (c). These substances may be contained in a single photographic component
layer or in two or more layers. Specifically, it is possible to add the components
(a), (b) and (d) to a single layer and the component (c) to an adjoining layer, or
to add (b), (c) and (d) to a single layer and (a) to another layer.
[0083] Two or more light-sensitive layers may have substantially the same kind of color
sensitivity, which layers may be prepared as low and high speed layers, respectively.
[0084] When using the heat developable light-sensitive material of the present invention
as a full-color recording material, it usually has three light-sensitive layers with
different kinds of color sensitivity, in which respective dyes with different hues
are formed or released upon heat development. In this case, it is the common practice
that the blue-sensitive layer (B) contains a yellow dye (Y), the green-sensitive layer
(G) contains a magenta dye (M) and the red-sensitive layer (R) contains a cyan dye
(C), i.e. (B-Y)-(G-M)-(R-C), but the present invention is not limited to these combinations,
i.e., any combination is acceptable. Specifically, possible combinations include (B-C)-(G-M)-(R-Y)
and (infrared-sensitive layer-C)-(G-Y)-(R-M).
[0085] These layers may take any configuration, including the layer configurations of R-G-B,
G-R-B, R-G-infrared and G-R-infrared as arranged from the support side.
[0086] The heat developable light-sensitive material of the present invention may be provided
with non-light-sensitive layers such as subbing layers, interlayers, protective layers,
filter layers, backing layers and peeling layers as well as light-sensitive layers.
[0087] When using the heat developable light-sensitive material of the present invention
for the dye transfer method, it is preferable to use an image receiving material.
The image receiving material comprises a support and an image receiving layer capable
of dye reception formed thereon, but the support itself may also serve as an image
receiving layer with such capability.
[0088] The heat developable light-sensitive material of the present invention can be so-called
a mono-sheet type heat developable light-sensitive material wherein a light-sensitive
layer and an image receiving layer have previously been laminated on the same support
as described in RD No. 15108 and Japanese Patent O.P.I. Publication Nos. 198458/1982,
207250/1982 and 80148/1986 and other publications.
[0089] The image receiving material for the present invention may incorporate various known
additives. Examples of such additives include antistaining agents, UV absorbents,
brightening agents, image stabilizers, developing accelerators, antifogging agents,
pH regulators (e.g., acids, acid precursors), thermal solvents, organic fluorine compounds,
oil drops, surfactants, hardeners, matting agents, antifungal agents and various metal
ions.
[0090] The heat developable light-sensitive material of the present invention can be exposed
to light in accordance with known exposure means suitable to the color sensitivity
of the light-sensitive material.
[0091] Examples of usable exposure light sources include tungsten lamps, halogen lamps,
xenon lamps, mercury lamps, CRT light sources, FO-CRT light sources, light emitting
diodes and laser sources (e.g., gas laser, dye laser, YAG laser, semiconductor laser),
all of which may be used singly or in combination. It is also possible to use light
sources comprising a combination of semiconductor laser and SHG element (second harmonic
wave generating element). Also, phosphors excited by electron beams, X-rays, γ-rays
or α-rays can also be used as light sources for exposure.
[0092] In the heat development of the heat developable light-sensitive material of the present
invention, a known heating means can be used; for example, it may be brought into
contact with a heated heat block, surface heater, heat roller or heat drum, it may
be passed through a hot atmosphere, it may be heated using high frequency wave heating,
and it may be heated with the Joule heat generated by supplying current to a heat
generating electroconductive material like a carbon black layer on the back face of
the light-sensitive material or image receiving material.
[0093] Heating for image formation using a recording material relating to the invention
(heat-sensitive recording material or heat developing type light-sensitive material)
is carried out substantially in the absence of water and base.
[0094] Hereinafter, the advantageous feature of the present invention will be illustrated
by exemplifying a transfer-type heat developable light-sensitive material containing
1-3-sulfur-nitrogen-containing compound as a dye-providing substance.
[0095] In other words, neither water nor base is externally added for this heating, nor
does the recording material itself contain a base or base precursor. When a hydrophilic
binder such as gelatin is used in the recording material or image-receiving material,
a trace amount of water is retained therein because of equilibrium with the atmosphere;
this condition is also included in "substantially in the absence of water" in the
present invention.
[0096] When the recording material containing a 1,3-sulfur-nitrogen-containing compound
contains a base or base precursor, a cleavage reaction of the 1,3-sulfur-nitrogen-containing
compound proceeds and results in image quality deterioration during long-term storage
or high-temperature or high-humidity storage of the recording material. Particularly
when the 1,3-sulfur-nitrogen-containing compound releases a dye, a problem of increased
fogging is posed.
[0097] When a base or base precursor exists during heating, imagewise regulation of the
reaction is difficult and image quality deterioration occurs. For example, when the
1,3-sulfur-nitrogen-containing compound releases a dye, fogging is markedly suppressed
as a result of acceleration of silver development by the base, but maximum density
reduction is also considerable.
[0098] Hitherto, 1,3-sulfur-nitrogen-containing compounds have been known to be used in
the presence of base. However, in the present invention, the presence of base is unnecessary,
on the contrary, the relationship between fog and maximum density improves significantly
because 1) reaction is carried out at high temperatures, and 2) the reaction is accelerated
by the presence of a thermal solvent.
[0099] The advantageous effects of the present invention can be ahieved especially noticeably
when the formation of image dyes by heat development and the transfer thereof to the
image-receiving material are conducted substantially not in the presence of water.
[0100] In the present invention, it is preferable to employ a hydrophobic polymer in an
image-receiving layer of the image-receiving material.
[0101] As hydrophobic polymers, polyvinyl chloride, polycarbonates, polyesters, polyarylates
and polystyrene are preferable, and polyvinyl chloride is especially preferable.
[0102] When a hydrophilic binder is used in the recording material of the present invention,
it is preferable to set the film surface pH of the recording layer at not more than
8.0, more preferably not more than 7.0 at 25°C. The film surface pH of the recording
layer is preferably kept within the above-mentioned range both before, during and
after heating for image formation.
[0103] Here, the film surface pH of the recording layer can easily be measured by dropwise
adding a small amount of pure water onto the surface of the recording layer and applying
a flat pH electrode thereon. The pure water used for this purpose is ion exchange
water or distilled water whose pH is 5 to 8 and whose electroconductivity is not more
than 1 µs/cm at 25°C. Specifically, a microsyringe is used to dropwise add about 10
µl of the pure water onto the surface of the light-sensitive layer, and a flat electrode
is applied thereto to obtain measurements.
EXAMPLES
[0104] The present invention is hereinafter described in more detail by means of the following
examples, but the invention is not by any means limited by them.
Example 1
Preparation of organic silver salt emulsion
[0105] While keeping a temperature of 50°C, to an aqueous solution (OA-1) containing 300
g of modified gelatin wherein over 90% of the amino groups have been substituted by
phenylcarbamoyl groups, 2400 ml of deionized water, 9.18 g of benzotriazole and 51
ml of 28% aqueous ammonia, 1420 ml of another aqueous solution (OB-2) containing 250
g of benzotriazole and 169 ml of 28% aqueous ammonia and 1420 ml of still another
aqueous solution (OC-1) containing 360 g of silver nitrate and 336 ml of 28% aqueous
ammonia were added at constant flow rate by the double jet precipitation method using
the mixer agitator described in Japanese Patent O.P.I. Publication Nos. 92523/1982
and 92524/1982. During the mixing process, pH and pAg were kept constant at 9.3 and
11, respectively. After completion of addition, a 20% aqueous solution of 60 g of
modified gelatin wherein over 90% of the amino groups have been substituted by phenylcarbamoyl
groups. Subsequently, 56% acetic acid was added to reach a pH level of 5.5. After
precipitation, the dissolved excess soluble salts were removed.
[0106] Further, 4800 ml of deionized water was added, and a 10% aqueous solution of potassium
hydroxide was added to reach a pH level of 6.0. After 5 minutes of dispersion, a 20%
aqueous solution of 30 g of the modified gelatin described above was added. Subsequently,
3.5 N sulfuric acid was added to reach a pH level of 4.5. After precipitation, the
dissolved excess soluble salts were removed. After adjusting to a pH level of 6.0
and adding 0.45 g of the following compound ST-1, deionized water was added to reach
a total quantity of 2520 ml, followed by 30 minutes of dispersion at 50°C to yield
an organic silver salt emulsion.

Preparation of thermal solvent dispersion 1
[0107] Using an alumina ball mill, 25 g of the following thermal solvent TS-12 was dispersed
in 100 ml of a 0.5% aqueous solution of polyvinylpyrrolidone containing 0.04 g of
surfactant 1 (Alkanol XC, produced by Du-Pont) to yield 120 ml of a dispersion.

Preparation of 1,3-sulfur-nitrogen-containing compound dispersion 1
[0108] Using an alumina ball mill, 12 g of the compound 37 of the present invention was
dispersed in 100 ml of a 1.5% aqueous solution of polyvinyl alcohol containing 0.01
g of surfactant 1 (Alkanol XC, produced by Du-Pont) to yield 120 ml of a dispersion.
Preparation of recording material 1
[0109] The following recording material was prepared using the organic silver salt dispersion,
thermal solvent dispersion and 1,3-sulfur-nitrogen-containing compound dispersion
prepared above.
Gelatin |
3.6 g/m² |
Compound 37 of the present invention |
1.3 g/m² |
Silver benzotriazole |
0.68 g/m² (as silver) |
Thermal solvent TS-12 |
6.0 g/m² |
Polyvinyl alcohol |
0.13 g/m² |
[0110] The support used was a latex-subbed transparent polyethylene terephthalate film having
a thickness of 100 µm.
Preparation of recording material 2
[0112] A recording material 2 was prepared in the same manner as with recording material
1 except that silver benzotriazole was not used.
Evaluation
[0113] The recording materials 1 and 2 thus obtained were heated by keeping in contact with
a 120°C metal plate for 60 seconds, followed by extraction with a 10:1 mixed solvent
of dimethylformamide and water, after which thin-layer chromatography (developing
solvent: CHCl₃:MeOH=8:2) for evaluation. The recording material 1, which contained
silver benzotriazole, yielded a diffusible dye released from the compound 37 of the
present invention, while the recording material 2 yielded an unchanged form of the
compound 37 of the present invention. It can therefore be said that the use of the
recording material of the present invention and a heating means such as a thermal
head makes it possible to provide a thermal recording material and a method of image
formation using it.
Example 2
[0114] Recording materials 1 (b) and 2 (b) were prepared in the same manner as in Example
1 except that the compound 37 of the present invention was replaced with the compound
38 of the present invention for the recording material 1 (b) and silver benzotriazole
was not used for the recording material 2 (b).
[0115] Heating was followed by extraction in the same manner as in Example 1, and evaluation
was made by thin-layer chromatography (developing solvent: hexane:ethyl acetate =
1:2). The results obtained were similar to those obtained in Example 1.
[0116] The recording materials 1 (b) and 2 (b) were heated at 120°C for 60 seconds and then
uniformly sprayed with a solution of 1% o-dianisidine in acetic acid. The recording
material 1 (b) developed an orange color, while the recording material 2 (b) remained
colorless. When the compound (38) was heated in the presence of benzotriazole silver,
a thiazolizing ring was presumably cleaved to form a diffusible aldehyde compound.
Example 3
[0117] Recording materials 3 through 19 were prepared in the same manner as in Example 1
except that the thermal solvent TS-12 used in Example 1 was replaced with the thermal
solvents listed in Table 1 below.
[0118] The recording materials 1 through 19 thus obtained were heated by keeping them in
contact with a 120°C hot metal plate for 45 seconds, followed by extraction using
the same solvent as in Example 1 and evaluation by thin-layer chromatography.
[0119] The results obtained are given in Table 1. The figures for reactivity in Table 1
were obtained on the basis of the size and density of the spots of the compound of
the present invention and a diffusible dye resulted from reaction with silver ions
on the thin-layer chromatograms. The relationship between reactivity and corresponding
spots on thin-layer chromatograms are as follows.
Reactivity (condition of the spot of the compound of the present invention or corresponding
aldehyde derivative)
5: The spot of the compound of the present invention disappeared; the diffusible dye
alone is present.
4: A thin spot of the compound of the present invention remains; almost the entire
spot is assigned to the diffusible dye.
3: The compound of the present invention and the diffusible dye each account for nearly
50%.
2: Almost the entire spot is assigned to the compound of the present invention; the
contribution of the diffusible dye is very small.
1: The spot of the compound of the present invention alone is present; no diffusible
dye formation noted.
Table 1
Recording material |
Hot melting substance |
Reactivity |
1 |
TS-12 |
5 |
2 |
TS-12 |
1 |
3 |
TS-1 |
3 |
4 |
TS-3 |
3 |
5 |
TS-4 |
3 |
6 |
TS-5 |
4 |
7 |
TS-6 |
4 |
8 |
TS-7 |
3 |
9 |
TS-8 |
4 |
10 |
TS-9 |
4 |
11 |
TS-10 |
4 |
12 |
TS-11 |
4 |
13 |
TS-14 |
5 |
14 |
TS-16 |
4 |
15 |
TS-17 |
4 |
16 |
TS-18 |
4 |
17 |
TS-19 |
4 |
18 |
TS-20 |
4 |
19 |
TS-21 |
4 |
Example 4
[0120] A recording material 20 was prepared with the organic silver salt dispersion, thermal
solvent dispersion and 1,3-sulfur-nitrogen-containing compound dispersion prepared
in Example 1 and a monodispersed silver iodobromide grain emulsion with an average
grain size of 0.25 µm chemically sensitized with sodium thiosulfate and the following
reducing agent 1. The amounts of these components used per m² are as follows.
Gelatin |
3.6 g |
Compound 37 of the present invention |
1.3 g |
Silver benzotriazole |
0.68 g (as silver) |
Thermal solvent TS-12 |
6.0 g |
Polyvinyl alcohol |
0.13 g |
Silver iodobromide |
0.45 g (as silver) |
Reducing agent 1 |
1.02 g |
[0121] The support used was a latex-subbed transparent polyethylene terephthalate film having
a thickness of 100 µm.
[0122] A recording material 20 (b) was prepared in the same manner as above except that
the compound 37 of the present invention was replaced with the compound 38 of the
present invention. The recording materials 20 (a) and 20 (b) were subjected to exposure
using a tungsten lamp as the light source. Exposed and unexposed recording materials
20 (a) and 20 (b) were heated, extracted and evaluated by thin-layer chromatography
in the same manner as in Examples 1 and 2. The exposed samples yielded an evidently
smaller amount of diffusible compounds corresponding to the compounds 37 and 38 of
the present invention in comparison with the unexposed samples.
[0123] It can therefore be said that the present invention makes it possible to suggest
the potential of the present invention for embodiment as a heat developable light-sensitive
material.

Example 5
Preparation of a 1,3-sulfur-nitrogen-containing compound dispersion- 2
[0124] 1,3-sulfur-nitrogen-containing compound of the present invention, as shown in Table
2 and 180 mg of tricrezylphosphate were dissolved in 1.2 ml of ethylacetate. Then,
the solution was mixed with 6.5 ml of an aqueous solution containing 132 mg of the
aforesaid surfactant and 150 mg of gelatin. Then, the mixed solution was emulsified
and dispersed with a supersonic homogenizer. After that, ethylacetate was distilled
off therefrom and deionized water was added to make 10 g in total. Thus, solutions
each containing therein 1,3-sulfur-nitrogen-containing compound were prepared.
Table 2
Compound |
Addition amount (mg) |
(41) |
672 |
(42) |
318 |
(45) |
612 |
(47) |
360 |
(58) |
491 |
(65) |
716 |
Preparation of a reducing agent dispersion
[0125] A Dimezone-dispersing solution was prepared by dispersing the mixture of 5.0 g of
Dimezone (1-phenyl-4,4-dimethyl-3-pyrazolidone), 5.0 ml of 5 weight % aqueous solution
of the above-mentioned surfactant-1 and 40 ml of ion-exchanged water by means of an
alumina ball mill. In the same manner as above except that Dimezone was replaced with
dimezone-S (4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone), a Dimezone-S dispersion
was prepared.
Preparation of heat developable light-sensitive material
[0126] Using dispersion prepared as above, an organic silver salt emulsion prepared in Example-1
(silver benzotriazole), a thermal solvent dispersion (TS-12) and a silver iodobromide
emulsion (an iodide content of 2 mol %), heat developable light-sensitive materials
101 and 102 were prepared.
[0127] An emulsion layer was coated on a 180 µm-thick PET support having thereon a subbed
layer, and dried. The coating amount of each compound in the emulsion layer is shown
as follows:
Gelatin |
3.0 g/m² |
Polyvinyl pyrrolidone |
0.02 g/m² |
Thermal solvent TS-12 |
1.5 g/m² |
1,3-Sulfur-nitrogen compounds as described in Table 3 |
Dimezone |
2.0 mmol/m² |
Silver iodobromide |
2.0 mmol/m² |
Silver benzotriazole |
1.0 mmol/m² |
1,2,4-Triazole |
24 mmol/m² |
Glyoxal |
0.06 g/m² |
[0128] In coating an emulsion layer, a small amount of the above-mentioned surfactant-1
and a small amount of Zonyl FSN (produced by Du Pont) were added as coating aids.
Preparation of an image-receiving material
[0129] On a baryta paper support for photographic use of 150 g/m², polyvinyl chloride of
12 g/m² was coated so that an image-receiving material was prepared.
Evaluation
[0130] By the use of a Xenon flash lamp, heat developable light-sensitive materials 101
and 102 were subjected to partial exposure for 10⁻³ seconds. Then, each of them was
superposed on an image-receiving material, and, they were heated uniformly for 60
seconds while being kept in contact with a metallic heat plate at 120 °C with a pressure
of 2 kg/cm².
[0131] After cooling, when the light-sensitive material was separated from the image-receiving
material, a positive type yellow image was obtained on the image-receiving layer.
[0132] The reflection density of the image was measured using a reflection densitometer
PDA-65 (produced by Konica). Results are shown in Table 3.
Table 3
Light-sensitive material |
Kind and added amount of 1,3-sulfur-nitrogen compound |
Reflective density |
|
|
Unexposed portion |
Exposed portion |
101 |
(41) 0.5 mmol/m² |
1.08 |
0.67 |
102 |
(45) 0.5.mmol/m² |
0.51 |
0.31 |
Example 6
[0133] Using an organic silver salt emulsion prepared in Example-1 (silver benzotriazole),
a thermal solvent-dispersion (TS-12), 1,3-sulfur-nitrogen-containing compound dispersion
prepared in Example 5, a reducing agent dispersion and a silver iodobromide emulsion
(an iodide content of 2 mol %), heat developable light-sensitive materials 201 through
207 having 2-layer constitution were prepared.
[0134] The first layer (layer-1) was coated on a 180 µm-thick PET support having thereon
a subbed layer, and dried. Then, the second layer (layer-2) was coated thereon and
dried.
[0135] Coating amount of each compound in the first layer and the second layer is shown
below.
[0136] In coating the first layer and the second layer, a small amount of the above-mentioned
surfactant-1 and a small amount of Zonyl FSN (produced by Du Pont) were added as coating
aids.
Layer-1 |
Gelatin |
2.0 g/m² |
Thermal solvent TS-12 |
Amount described in Table 4 |
Polyvinyl pyrrolidone |
0.02 g/m² |
1,3-Sulfur-nitrogen-containing compound, as described in Table 4 |
Layer-2 |
Gelatin |
3.0 g/m² |
Polyvinyl pyrrolidone |
0.02 g/m² |
Thermal solvent TS-12 |
1.5 g/m² |
Reducing agent, as described in Table 4 |
Silver iodobromide |
Amount described in Table 4 |
Silver benzotriazole |
Amount described in Table 4 |
1,2,4-Triazole |
24.0 mmol/m² |
Glyoxal |
0.1 g/m² |

[0137] Heat developable light-sensitive materials 201 through 206 were subjected to light
exposure and heat-developing in the same manner as in Example 5, provided that the
conditions of heating were changed as shown in Table 4.
[0138] After cooling, when the light-sensitive material was separated from the image-receiving
material, a positive-type yellow or magenta image was obtained on the image-receiving
material.