JPH0815809A - Image forming medium and image forming method using same - Google Patents

Abstract

PURPOSE:To provide the image forming medium and the image forming method using this medium both superior in fog restraint, raw stock storage stability, and light discoloration restraint. CONSTITUTION:The image forming medium contains at least an organic silver salt, a reducing agent, and a dihalogenated olefin, or in addition to these components, further, photosensitive silver halide or a photosensitive silver halide forming agent in a recording layer on a support, and thus image forming medium is imagewisely heated or imagewisely exposed and heated to form an image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming medium on which an image is formed by a redox reaction and an image forming method using the image forming medium.

[0002]

2. Description of the Related Art Recently, various recording materials have been researched and developed in the field of information recording, medical field, etc., and put to practical use in response to social demands such as diversification and increase of information, resource saving and pollution-free. Has been done. Among them, the thermal recording material is
(1) A single color image is recorded by simply heating and no complicated developing process is required, (2) Manufacture using a relatively simple and compact device, (3) Maintenance cost is low Widely used by

However, the thermal recording system using the thermal head has limitations in high-speed control of heating and cooling of the heating element and high density of the heating element due to the structure of the thermal head, and therefore, further high-speed recording and high-speed recording are possible. It was difficult to record density and high image quality.

In order to solve this drawback, it has been proposed to use a laser beam to perform thermal recording on a thermal recording material in a non-contact, high speed and high density manner (for example, Japanese Patent Laid-Open No. 50-23617). JP-A-54-12114
No. 0, JP 57-11090 A, JP 58.
-94494, JP-A-62-56195, etc.). However, since the thermosensitive coloring layer generally does not easily absorb light in the visible and near-infrared regions, there is a problem that the thermal energy required for coloring cannot be obtained unless the output of the laser is considerably increased.

On the other hand, as a method capable of high-speed recording, high-density recording, and high-quality recording even with a low-output laser, Japanese Patent Publication Nos. 43-4921 and 43-4924,
JP-B-44-26582 and JP-A-46-607.
There is known a method of forming an image by optical writing and thermal development disclosed in Japanese Patent Publication No. 4 or the like. This image forming method uses a photosensitive silver halide in a catalytic amount and a non-photosensitive organic silver salt as an image forming material. Further, Japanese Patent Application Laid-Open No. 48-97523 describes a method of forming an image by giving a heat-developable light-sensitive material containing no silver halide to heat it so as to activate the heat-developable light-sensitive material. .

[0006]

In the conventional method of forming an image by heat, fog (discoloration in the non-image area) is apt to occur, and for this reason, there is a problem in Japanese Patent Application Laid-Open No. 47-11113 and U.S. Pat. No. 3,589. No. 903, it is described that a small amount of a compound that gives a mercury (II) ion is used to prevent fog.

However, as is well known, mercury compounds are toxic, and there have been problems in using mercury compounds as antifoggants. Thus, as non-toxic, US Pat. No. 4,055,432 discloses dicarbonyl-substituted imides,
JP-A-49-10724 discloses N-chlorosuccinimide and N-bromosuccinimide.
No. 126421 discloses halogenated compounds, US Pat. No. 4,212,937 combines nitrogen-containing organic bases with halogen molecules or organic halomids, and US Pat. No. 4,152,160 discloses various compounds. Carboxylic acids such as benzoic acid and phthalic acid having substituents of However, all of these antifoggants have insufficient antifoggant ability, and some of them deteriorate light resistance, so that they are not satisfactory. In particular,
Conventional antifoggants deteriorate when left in high temperature and high humidity for a long time.

The present invention has been made in view of the above circumstances, and provides an image forming medium excellent in suppression of fog, stability in raw storage, and suppression of printing (discoloration) due to light, and an image forming method using the same. The purpose is to do.

[0009]

The image forming medium of the present invention contains at least an organic silver salt, a reducing agent, and a dihalogen-substituted olefin in a recording layer on a support.
Alternatively, the recording layer further contains a photosensitive silver halide or a photosensitive silver halide forming agent in addition to the above components.

The image forming method of the present invention is to form an image on the above image forming medium by imagewise heating, or imagewise exposure and heating.

The present invention will be described in detail below. In the following description, "part" means "part by weight".

The image forming medium of the present invention has a recording layer containing at least an organic silver salt, a reducing agent and an antifoggant on a support.

In the present invention, a dihalogen-substituted olefin is used as an antifoggant. The dihalogen-substituted olefin used in the present invention may be a cis-olefin or a trans-olefin. Further, the dihalogen-substituted olefin is preferably one in which a halogen atom is bonded to each of the two carbons linked by a double bond. These two halogen atoms may be the same or different. The halogen atom is preferably bromine, iodine or chlorine.

The substituent bonded to the same carbon atom as the halogen atom is preferably, for example, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group or an alkyl group.

The dihalogen-substituted olefin used in the present invention is particularly preferably a cis or trans olefin represented by the following general formula (1).

[0016]

[Outside 2] (In the formula (1), X ₁ and X ₂ represent a halogen atom. R
₁ and R ₂ represent a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group or an alkyl group. ) The substituent bonded to the aryl group has, for example, 1 carbon atom.
To 20 alkyl groups, nitrile groups, nitro groups, alkoxy groups, and halogen atoms such as bromine, chlorine, iodine and fluorine are preferable. Examples of the alkyl group having 1 to 20 carbon atoms include linear alkyl groups such as methyl, ethyl, propyl, octyl, nonyl and behenyl groups, and branched alkyl groups such as isopropyl, isobutyl and isopentyl.

Preferred substituted or unsubstituted aryl groups are, for example, phenyl, naphthyl, anthranyl,
2-nitrophenyl, 2,3-dinitrophenyl, 4-
Nitrophenyl, 3,4-dinitrophenyl, 4-alkylphenyl, 3-alkylphenyl, 2-cyanophenyl, 3-cyanophenyl, 4-cyanophenyl, 3-
Methoxyphenyl, 4-methoxyphenyl, 4-trifluoromethyl, 2-halogen-substituted phenyl, 3-halogen-substituted phenyl, 4-halogen-substituted phenyl, 2,3-
Examples thereof include halogen-substituted phenyl and 3,4-halogen-substituted phenyl.

Examples of the substituted or unsubstituted heterocyclic group include pyridyl, pyridazinyl, quinolyl, indoyl,
Furyl, thienyl, pyrrolyl, imidazoyl, isothiazoyl, isoxazoyl and the like are preferable.

The alkyl group has, for example, 1 to 2 carbon atoms.
A straight chain or branched alkyl group of 0 is preferred. Such examples include straight chains such as methyl, ethyl, propyl, pentyl, octyl, nolyl and behenyl, isopropyl,
Examples thereof include branched alkyl groups such as isobutyl and isopentyl, and aralkyl groups such as benzyl group.

The dihalogen-substituted olefin compound used in the present invention is, for example, Chemistry Lette.
r, 1984 , 1969 etc., and can be easily synthesized.

Preferred examples of the dihalogen-substituted olefin used in the present invention are shown below.

Α, β-dibromostilbene, α, β-dibromo-4,4'-dinitrostilbene, α, β-dibromo-4,4'-dicyanostilbene, α, β-dibromo-2,2 ', 4. 4'-tetracyanostilbene,
α, β-dibromo-4,4′-di-t-butylstilbene, α, β-dibromo-4,4′-dichlorostilbene, α, β, 4-4′-tetrabromostilbene, α,
β-dibromo-4,4′-difluorostilbene, α,
β-dibromo-2,2 ′, 4,4′-tetrachlorostilbene, 1,2-dibromo-di (3-pyridazinyl) ethylene, 1,2-dibromo-di (4-pyrimidinyl) ethylene, α, β- Dichlorostilbene, α, β-dichloro-4,4′-dinitrostilbene, α, β-dichloro-4,4′-dicyanostilbene, α, β-dichloro-
2,2 ', 4,4'-tetracyanostilbene, α, β
-Dichloro-4,4'-di-t-butylstilbene,
α, β-dichloro-4,4′-dichlorostilbene,
α, β, 4,4'-tetrachlorostilbene, α, β-
Dichloro-4,4'-difluorostilbene, α, β-
Dichloro-2,2 ', 4,4'-tetrachlorostilbene, 1,2-chloro-di (3-pyridazinyl) ethylene, 1,2-dichloro-di (4-pyrimidinyl) ethylene, 1,2-dichloro- Di (2-naphthyl) ethylene,
1,2-dibromo-di (2-naphthyl) ethylene, 1,
2-dibromo-di (2-benzothiazoyl) ethylene,
1,2-dichloro-di (2-benzothiazoyl) ethylene, 1,2-dibromo-di (2-benzoxazoyl)
Ethylene, 1,2-dichloro-di (2-benzoxazoyl) ethylene, 1,2-dibromo-di (2-thienyl) ethylene, 1,2-dichloro-di (2-thienyl)
Ethylene, 1,4-diphenyl-2,3-dibromo-2
-Butene, 3,4-dibromo-3-heptene, 4,5-
Dibromo-4-octene, 2-ethyl-3,4-dibromo-octene, 1,4-diphenyl-2,3-dichloro-2-butene.

The antifoggant used in the present invention has a stable antifoggant function and does not deteriorate even under severe environmental conditions. Therefore, the image forming medium of the present invention does not cause fog even after long-term raw storage (preservation in an unused state).

As the organic silver salt, "basics of photographic engineering"
(The Photographic Society of Japan, Corona Co., Ltd., Tokyo, 1st edition, 1
982) Non-silver salt edition P247 and JP-A-59-55
It is possible to use the organic silver salts and triazole silver salts described in JP-A No. 429, etc., and it is preferable to use silver salts having low photosensitivity. For example, it is a silver salt of an aliphatic carboxylic acid, an aromatic carboxylic acid, a thiol, a thiocarbonyl compound having α-hydrogen, and an imino group-containing compound.

As the aliphatic carboxylic acid, acetic acid, butyric acid,
There are succinic acid, sebacic acid, adipic acid, oleic acid, linoleic acid, linolenic acid, tartaric acid, palmitic acid, stearic acid, behenic acid, etc., but generally, the smaller the carbon number, the more unstable the silver salt. Therefore, a compound having an appropriate carbon number (for example, a carbon number in the range of 15 to 28) is preferable.

As the aromatic carboxylic acid, benzoic acid derivative, quinolinic acid derivative, naphthalenecarboxylic acid derivative,
Salicylic acid derivative, gallic acid, tannic acid, phthalic acid,
Examples include phenylacetic acid derivatives and pyromellitic acid.

Examples of the thiocarbonyl compound having a thiol or α-hydrogen include 3-mercapto-4-phenyl-1,2,4-triazole, 2-mercaptobenzimidazole, 2-mercapto-5-aminothiadiazole and 2-mercapto. Benzothiazole, S-alkyl thioglycolic acid (alkyl group having 12 to 23 carbon atoms),
Dithiocarboxylic acids such as dithioacetic acid, thioamides such as thiostearoamide, 5-carboxy-1-methyl-2-phenyl-4-thiopyridone, mercaptotriazine, 2-mercaptobenzoxazole, mercaptooxathiazole or 3-amino- 5-benzylthio-
1,2,4-triazole, US Pat.
The mercapto compound described in No. 3,274 can be mentioned.

Examples of the compound containing an imino group include JP-B-44-30270 and JP-B-45-18416.
Benzotriazole or its derivative described in Japanese Patent Publication No.
For example, alkyl-substituted benzotriazoles such as benzotriazole and methylbenzotriazole, halogen-substituted benzotriazoles such as 5-chlorobenzotriazole, carboimide benzotriazoles such as butylcarbimidobenzotriazole, and JP-A-58-118.
No. 6,220,709, such as nitrobenzotriazoles described in JP-A-639, sulfobenzotriazole, carboxybenzotriazole or a salt thereof described in JP-A-58-115638, and hydroxybenzotriazole. Typical examples include 2,4-triazole, 1H-tetrazole, carbazole, saccharin, imidazole and derivatives thereof.

As the reducing agent, all materials (preferably organic materials) capable of reducing silver ions to metallic silver can be used.

Examples of such reducing agents include monophenols, bisphenols, trisphenols, tetrakisphenols, mononaphthols, bisnaphthols, hydroxynaphthalenes, sulfonamidephenols, biphenols and trihydroxynaphthalenes. ,
Dihydroxybenzenes, trihydroxybenzenes,
Tetrahydroxybenzenes, hydroxyalkyl monoethers, ascorbins, 3-pyrazolidones, pyrazolones, pyrazolines, sugars, phenylenediamines, hydroxyamines, reductones, hydrooxamic acids, hydrazines, hydrazides, amides Examples thereof include oximes and N-hydroxyureas.
Among these, p-bisphenols, o-bisphenols, bisnaphthols, 4-substituted naphthols and the like are particularly preferable. Further, the reducing agent described in JP-A-3-135564 is also preferably used.

The recording layer preferably contains an appropriate binder for the purpose of improving the coating property and dispersibility of the recording layer. Examples of binders include cellulose esters such as nitrocellulose, cellulose phosphate, cellulose sulfate, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose myristate, cellulose palmitate, acetic acid / cellulose propionate, and acetic acid / butyrate cellulose. Ethers of cellulose such as methyl cellulose, ethyl cellulose, propyl cellulose and butyl cellulose; vinyl polymers such as polystyrene, polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol and polyvinyl pyrrolidone; styrene-ptadiene copolymer , Styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, etc. Polymers like; polymethyl methacrylate, polymethyl acrylate, polybutyl acrylate, polyacrylic acid, polymethacrylic acid, polyacrylamide, acrylic polymers such polyacrylonitrile, polyesters such as polyethylene terephthalate;
Poly (4,4-isopropylidene-diphenylene-co-
1,4-cyclohexylene dimethylene carbonate),
Poly (ethylenedioxy-3,3'-phenylene thiocarbonate), poly (4,4'-isopropylidene-diphenylene carbonate-co-terephthalate), poly (4,4-isopropylidene-diphenylene carbonate), Poly (4,4'-sec-butylidenephenylene carbonate), poly (4,4'-isopropylidene-
Polyphenylene polymers such as diphenylene carbonate-block-oxyethylene); polyamides; polyimides; epoxy polymers; phenolic polymers;
Polyolefins such as polyethylene, polypropylene and chlorinated polyethylene; and natural or synthetic resins such as gelatin.

Particularly, polyvinyl acetals such as polyvinyl butyral and polyvinyl formal, and vinyl copolymers such as vinyl chloride vinyl acetate copolymer are preferable.

In the image forming medium of the present invention, the preferable compounding ratio of each component is as follows.

The content of the organic silver salt is 5 to the recording layer.
70% by weight, more preferably 10 to 60% by weight, particularly preferably 20 to 50% by weight. Even when the recording layer is composed of multiple layers as described later, the content of the organic silver salt is the above value for all recording layers.

The content of the reducing agent is preferably 0.05 to 3 mol, more preferably 0.2 to 2 mol, based on 1 mol of the organic silver salt.

The content of the dihalogen-substituted olefin is preferably 0.001 to 0.5 mol, more preferably 0.005 to 0.2 mol, based on 1 mol of the organic silver salt.

The amount of the binder contained as necessary is preferably 0.5 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, relative to 1 part by weight of the organic silver salt.

To further improve the sensitivity and image quality, a photosensitive silver halide may be contained in the recording layer so that writing can be performed by light.

Examples of the photosensitive silver halide include silver chloride, silver bromide, silver chlorobromide, silver iodobromide, silver chloroiodobromide and the like.

As a method for preparing these silver halides, a part of the silver oxide compound is halogenated with a photosensitive silver halide-forming component such as ammonium bromide, lithium bromide, sodium chloride or N-bromosuccinimide. And a so-called external silver halide is contained.

The shape of these silver halide crystals may be cubic, octahedral, or tabular, but cubic or tabular silver halide is particularly preferred. The length of one side of the cubic silver halide crystal is preferably 0.01 to 2 μm, more preferably 0.02 to 1.3 μm.

These silver halides may be subjected to chemical sensitization as in a usual photographic emulsion. That is, sulfur sensitization, noble metal sensitization, reduction sensitization and the like can be used.

Further, these silver halides may contain Ir. Its content is 1 per mol of silver halide.
It is preferably from 10 ⁸ to 1 × 10 ^-4 mol, more preferably from 1 × 10 ^-7 to 1 × 10 ^-6 mol. The Ir content is 20% by weight, preferably 10% by weight, on the shell side of the silver halide crystal.

Further, these silver halides may have a multiple structure in which the halogen composition in the grain is uniform or different, and two or more kinds of silver halides having different halogen composition, grain size, grain size distribution, etc. You may use together.

The preferable content of the photosensitive silver halide, which is optionally contained, is 0.001 to 1 mol per mol of the organic silver salt.
2 mol, especially 0.05 to 1 mol is preferred.

A photosensitive silver halide forming agent (for example, a halogen compound such as tetrabutylammonium bromide, N-bromosuccinimide, bromine or iodine) may be used in place of the photosensitive silver halide, in which case silver halide formation is carried out. The content of the agent can be considered as in the case of silver halide.

The recording layer may contain a sensitizing dye such as a cyanine dye or a merocyanine dye. When a sensitizing dye is contained, the content is 1 × 10 ^-7 to 1 per mol of the organic silver salt.
× 10 ^-2 mol is preferable.

In the present invention, various compounds can be added to the recording layer.

The image forming medium of the present invention may contain a toning agent, if desired. Examples of the toning agent include phthalazinone or a derivative thereof described in U.S. Pat. No. 3,080,254, cyclic imides described in JP-A-46-6074, and phthalazinone compound described in JP-A-50-32927. Etc. can be mentioned.

The image forming medium of the present invention may contain an organic acid, if necessary, in order to improve the color tone of the image and the stability after the image is formed. In particular, a long chain fatty acid is used alone or in combination. It is preferably contained.

The image forming medium of the present invention may contain an anti-coloring agent, if necessary, in order to prevent coloring of the non-image area due to light after image formation. As the coloring preventing agent, for example, compounds described in JP-A No. 61-129642 are preferable.

The image forming medium of the present invention may further contain a development accelerator, if necessary. Preferred development accelerators include alkali metal salt compounds of fatty acids described in JP-B No. 64-8809.

The image forming medium of the present invention may contain an antistatic agent, if necessary. As an antistatic agent,
A fluorinated surfactant can be used, or a combination of a fluorinated surfactant and a nonionic surfactant described in JP-A No. 64-24245 can be used.

In the image forming medium of the present invention, if necessary, an ultraviolet absorber, an anti-irradiation dye, a matting agent,
A fluorescent whitening agent or the like can be contained.

In the image forming medium of the present invention, if necessary, an N-haloamide compound described in JP-A-49-90118, a sulfinic acid or a salt thereof described in JP-A-50-123331, and JP-A- 2-Thiouracils described in JP-A-51-3223, rosins and terpenes described in JP-A-51-57435, oxazoline compounds described in JP-A-51-2431, and JP-A-51-122.
Other thermal antifoggants such as benzotriazoles and benzenethiosulfonic acids described in JP-A No. 430, and mercaptotetrazoles described in JP-A No. 51-6016 may be contained.

Examples of the support include synthetic resin films of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, cellulose acetate, etc., synthetic paper, paper coated with synthetic resin films of polyethylene, art paper, photographic bariter paper, etc. Paper, a metal plate (foil) such as aluminum, a synthetic resin film having a metal vapor deposition film, or a glass plate.

Further, in order to increase the transparency of the image forming medium, increase the image density, improve the raw storability and, in some cases, the heat resistance of the image forming medium, a protective layer may be provided on the heat-sensitive recording layer. Can be provided. The suitable thickness of the protective layer is 1 to 20 μm. If it is thinner than this, the above effects are lost, and if it is too thick, there is no special advantage and only the cost is increased. The polymer used for the protective layer is preferably heat resistant, colorless, and easily soluble in a solvent, for example, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer (preferably 50 mol% vinyl chloride). Above), polyvinyl butyral, polystyrene, polymethyl methacrylate, benzyl cellulose, ethyl cellulose, cellulose acetate butyrate, cellulose diacetate, cellulose triacetate,
Polyvinylidene chloride, chlorinated polypropylene, polyvinylpyrrolidone, cellulose propionate, polyvinyl formal, polycarbonate, cellulose acetate propionate, gelatin, gelatin derivatives such as phthalated gelatin, acrylamide polymer, polyisobutylene, butadiene-styrene copolymer (any (Monomer ratio), polyvinyl alcohol, etc. can be mentioned.
In addition to these binders, colloidal silica may be contained in the protective layer.

Preferred polymers for the protective layer are those having a heat resistance of 115 ° C. or higher and a refractive index of 1.45 or higher at 20 ° C.

In the image forming medium of the present invention, a recording layer can be formed on the support as a single layer or multiple layers. When the recording layer has a multilayer structure, it is preferable that the recording layer has a layer containing an organic silver salt and an antifoggant and a layer containing a reducing agent.

When each layer having various functions such as a recording layer and a protective layer is separately formed in the image forming medium of the present invention, each of these layers can be coated by various coating methods. Examples of the method for forming each layer include a dipping method, an air knife method, a curtain coating method, a gravure coating method, a doctor coating method, and US Pat. No. 2,681,294.
There is an extrusion coating method using a hopper described in the specification. If desired, two or more layers can be coated simultaneously.

Next, a method of forming an image using the image forming medium of the present invention will be described.

When the image forming medium of the present invention is imagewise heated by using a thermal head or a laser beam, an oxidation-reduction reaction proceeds to form an image. The energy amount of the laser beam is preferably 0.5 mJ / cm ² or more on the medium surface. The heating temperature by the thermal head is 140 ~
It is preferably 250 ° C, more preferably 150 to 220 ° C. The heating time by the thermal head is preferably 0.01 to 2 seconds.

When an image is formed using a laser beam, the image forming medium of the present invention may contain a photothermal conversion material capable of efficiently converting light energy into heat energy. As such a light-heat conversion material, for example, inorganic metals or organic facial dyes are preferable, and a wavelength of 600 n is particularly preferable.
Those that absorb light of m or more are preferable.

As the inorganic metals used for the photothermal conversion material, for example, carbon black, silicate and the like are preferable.
Examples of organic facial dyes include polymethine dyes, azulene dyes, pyrylium dyes, merocyanine dyes, cyanine dyes, rhodamine dyes, naphthoquinone dyes, phthalocyanine dyes, fluorene dyes, aminium dyes, diimonium dyes, azo pigments, perylene pigments, metal chelate compounds. Etc. are preferred.

When the photothermal conversion material is contained, the content of the photothermal conversion material is preferably 0.1 to 30% by weight based on the recording layer.

On the other hand, the image forming medium of the present invention containing a silver halide or a silver halide forming component exhibits good photosensitivity and heat developability. That is, for the image forming medium of the present invention,
When exposure according to a desired image is performed with an appropriate light source, silver nuclei are first generated to form a latent image. Further, if this is appropriately heated, an image corresponding to the image exposure is developed by the redox reaction. As the light source in this case, for example, a semiconductor laser or LED light can be used.
The exposure speed is 1 × 10 ⁻³ sec / dot to 1
Even if the exposure time is up to × 10 ^-7 sec / dot, a practical optical density can be obtained without causing reciprocity law failure, but front sub-exposure or post-sub-exposure may be performed as necessary.

There are various means for heat-developing the image forming medium of the present invention containing a silver halide or a silver halide-forming component. For example, a photoreceptor may be brought into contact with a simple heating plate or a heated drum. May be brought into contact with, or may be passed through a heated space in some cases. Moreover, you may heat by a high frequency heating or a laser beam. The heating temperature is 70 to 160 ° C, and further 90 to
150 ° C is suitable, and more preferably 100 to 140
° C. By extending or shortening the heating time,
It is possible to perform heat development at a higher or lower temperature within the above temperature range. The developing time is usually 1 to 60 seconds, preferably 3 to 20 seconds. Since the heat development is performed with low energy, the end-exposed portion is not discolored.

[0068]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

Example 1 A polyethylene terephthalate (PET) film having a thickness of 25 μm was used as a support.

An aluminum layer having a thickness of 0.1 μm was formed on this support by vacuum deposition. Then,
A solution consisting of 50 parts of methyl ethyl ketone, 50 parts of toluene and 5 parts of vinyl chloride-vinyl acetate-maleic acid copolymer (manufactured by Nippon Zeon Co., Ltd.) on the aluminum layer was dried to a thickness of 0.5 μm using a wire bar. Was applied to form a primer layer.

Further, 3 parts of a 5.0% by weight solution of α, β-dibromo-4,4'-difluorostilbene in acetone was added to a solution having the following composition on the primer layer per 1 m ² . Was coated so that the amount of silver was 2.4 g to form a recording layer.

Silver behenate 1.0 part Behenic acid 0.5 part 2,2′-methylenebis (6-t-butyl-4-methylphenol) 1. 0 part Vinyl chloride-vinyl acetate copolymer 2.5 parts 1,3-pentadiene polymer 0.2 parts Tetrahydrofuran 12.0 parts

Further, vinyl acetate resin (number average degree of polymerization: 500
A 10% ethyl acetate solution of 0) was applied onto the recording layer so as to have a dry film thickness of 1 μm to form a protective layer, and an image forming medium of the present invention was obtained.

The image-forming medium thus obtained was recorded with a heat-sensitive evaluation machine (TH-PMD manufactured by Okura Electric Co., Ltd.),
The optical densities of the heated part and the non-heated part were measured with a Macbeth densitometer (RD-914 type manufactured by Macbeth Co.). The optical density was measured immediately after the image forming medium was prepared and after the image forming medium was prepared.
The test was performed for 72 hours (raw preservation test) in an environment of 0 ° C. and 80% RH. A voltage was applied to the thermal head of the heat-sensitive evaluation machine under the condition of 24V-2mS. The measurement results are shown in Table 1.

The image-forming medium obtained as described above was allowed to stand for 7 days without direct recording in a place exposed to direct sunlight, and the degree of discoloration of the image-forming medium was measured by the above Macbeth densitometer ( Light resistance test). The measurement results are shown in Table 1.

[Examples 2 and 3 and Comparative Example 1] The following compounds were added in place of α, β-dibromo-4,4′-difluorostilbene of Example 1, and the other components were the same as in Example 1. An image forming medium was prepared. An image forming medium was prepared in the same manner as in Example 1 except that α, β-dibromo-4,4′-difluorostilbene was not added (Comparative Example 1).

Example 2 1,4-diphenyl-2,3
-Dibromo-2-butene Example 3 1,2-Dibromo-di (2-benzothiazoyl) ethylene

The same measurement as in Example 1 was performed on each of the image forming media thus obtained. The measurement results are shown in Table 1.

[0079]

[Table 1]

Example 4 An image forming medium of the present invention was obtained in the same manner as in Example 1 except that 0.5 part of the following photothermal conversion material was added to the coating liquid for the recording layer prepared in Example 1. It was

[0081]

[Outside 3]

The thus-obtained image forming medium was recorded with a semiconductor laser having a wavelength of 780 nm, and the optical density of the heated portion and the non-heated portion was measured in the same manner as in Example 1. The exposure speed of the semiconductor laser was 1 msec / dot.
The energy of the semiconductor laser was 50 mJ / mm ^{2 on the} surface of the image forming medium. The measurement results are shown in Table 2.

A light resistance test was conducted on this image forming medium in the same manner as in Example 1. The results are shown in Table 2.

[0084]

[Table 2]

Example 5 A light and heat sensitive composition having the following composition was prepared under safe light.

Polyvinyl butyral 5.0 parts Silver behenate 2.5 parts Behenic acid 2.0 parts Silver bromide 0.2 parts 2,2′-Methylenebis (6-t-butyl-4-methylphenol) 1.0 Part Phthalazinone 1.0 part xylene 30 parts n-butanol 30 parts

The above silver bromide has a crystal fraction index of [10
0] cubic crystal, and the average length of one side of the crystal was 0.07 μm.

This composition contains the above-mentioned α, β-dibromo-
A recording layer was prepared by adding 3 parts of a 5.0 wt% acetone solution of 4,4′-dicyanostilbene onto a PET film support having a thickness of 25 μm so that the dry film thickness was 10 μm, and A polyvinyl alcohol layer having a dry film thickness of 2 μm was applied as a protective layer on the recording layer to obtain an image forming medium of the present invention.

The image forming medium thus obtained was irradiated with light using a tungsten light source. Light irradiation was performed through a mask with an exposure amount of 15000 lux seconds. After the light irradiation, the image forming medium was heated at 120 ° C. for 10 seconds for thermal development.

With respect to the image forming medium on which an image was formed in this way, the optical densities of the exposed part and the unexposed part were measured using a transmission / reflection combined color densitometer (NLM-STD-Tr, manufactured by Narumi Shokai). The measurement of the optical density was carried out immediately after the image forming medium was prepared and after it was left in an environment of 50 ° C. and 80% RH for 72 hours (raw preservation test). The measurement results are shown in Table 3.

The image-forming medium obtained as described above was placed under a fluorescent lamp for 1 hour without recording, and the degree of discoloration of the image-forming medium was measured with the above-mentioned transmission / reflection color densitometer ( Light resistance test). The measurement results are shown in Table 3.

[Examples 6 and 7, Comparative Examples 2 and 3] Example 5
An image forming medium was prepared in the same manner as in Example 5, except that the following compounds were added instead of α, β-dibromo-4,4′-dicyanostilbene. An image forming medium was prepared in the same manner as in Example 5 except that α, β-dibromo-4,4′-dicyanostilbene was not added (Comparative Example 2). Further, 1 part of mercuric bromide (5.0 wt% methanol solution) was added in place of α, β-dibromo-4,4′-dicyanostilbene, and otherwise the same as in Example 5 to form an image forming medium. Was prepared (Comparative Example 3).

Example 6 α, β-dibromo-4,4 '
-Dinitrostilbene Example 7 α, β-dichloro-4,4'-dicyanostilbene

The same measurement as in Example 5 was performed on each of the image forming media thus obtained. The measurement results are shown in Table 3.

[0095]

[Table 3]

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INDUSTRIAL APPLICABILITY As described above, the present invention is excellent in suppression of fog, stability in raw storage, and suppression of printout (discoloration) due to light.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motokazu Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (7)

[Claims] 1. An image forming medium containing at least an organic silver salt, a reducing agent, and a dihalogen-substituted olefin in a recording layer on a support. 2. The image forming medium according to claim 1, wherein the dihalogen-substituted olefin has a halogen atom bonded to each of two carbons connected by a double bond. 3. The image forming medium according to claim 2, wherein the substituent bonded to the same carbon as the halogen atom is a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, or an alkyl group. 4. The image forming medium according to claim 1, wherein the dihalogen-substituted olefin is a cis or trans olefin represented by the following general formula (1). [Outside 1] (In the formula (1), X ₁ and X ₂ represent a halogen atom. R
₁ and R ₂ represent a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group or an alkyl group. ) 5. The image forming medium according to claim 1, wherein the recording layer further contains a photosensitive silver halide or a photosensitive silver halide forming agent. 6. An image forming method, wherein the image forming medium according to claim 1 is imagewise heated to form an image. 7. An image forming method comprising forming an image by performing image exposure and heating on the image forming medium according to claim 5.