JPH07295138A - Image forming method - Google Patents

Abstract

PURPOSE:To uniformize the sensitivity of a photosensitive body and obtain a stable image by setting the temperature of the photosensitive body at exposure time above the glass transition point of a binder used for the photosensitive body and below the fusion point of a thermal solvent. CONSTITUTION:An optical system consists of a semiconductor laser light source 1, a collimator lens 2, a polygon mirror 3 for beam scanning, and an f-theta lens 4 for light convergence. Light given image information by this optical system is cast on the filmy photosensitive body 6. At this time, an exposure support roll 5 is brought under the temperature control of a heater 5a and exposure is performed at a desired temperature. The exposed photosensitive body 6 is sent by a conveyor roller 7 to a thermal developing roll, where the photosensitive body is heated and developed by a surface type heat generation body 8a to obtain an output image. In this case, the temperature of the photosensitive body at the exposure time is set above the glass transition point of the binder and blow the fusion point of the thermal solvent, and consequently a reducing agent and a color tone agent which are localized at coating time and storing time are redispersed to increase the production efficiency of a latent image formed by the exposure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for obtaining an image by exposing it with light, especially a laser beam, and then developing it. It is about the method.

[0002]

2. Description of the Related Art There is a method of converting an image information signal into light and irradiating a light-sensitive material such as silver halide to output an image. Among them, narrow-bandwidth light sources such as laser light and L
When an ED or the like is used, it is possible to irradiate in a minute spot, and since the energy density is high, it is possible to output a high-speed and high-resolution image.

On the other hand, in a light-sensitive material containing silver halide as a main component, a latent image formed by irradiation with light has been conventionally developed by a wet development process. For example, Japanese Patent Publication No. 43-4924. As shown in, by the development of a heat developable material that develops by applying heat,
It has become possible to obtain images more easily and quickly.

[0004]

However, in a conventional type light-sensitive material containing silver halide as a main component, a sufficient illuminance failure caused by high-speed recording, as known as reciprocity law failure, causes a sufficient image quality. There was a problem that the concentration could not be obtained. In particular, the effect of recording an isolated dot in which adjacent pixels are not recorded is large, and as a result, even if the same energy is applied, the density of the image differs between the isolated dot and the part in which the adjacent pixel is recorded. Occurs.

When the above-mentioned heat-developable light-sensitive material is used, when the temperature at the time of exposure is low, the reducing agent or the toning agent contained in the light-sensitive layer may be locally affected by the environment during coating or storage. It is considered that this is a cause of the deterioration of the sensitivity of the photoconductor and the variation of the sensitivity.

The present invention has been made to solve the above-mentioned problems, and the sensitivity of the photosensitive member is controlled by using a heat developing type photosensitive member and heating the photosensitive member during exposure to control the temperature thereof. To obtain a good image.

[0007]

That is, the present invention provides a photoreceptor having a photothermographic layer containing at least an organic silver salt, a photosensitive silver halide, a reducing agent, a thermal solvent and a binder on a support. In the image forming method, which comprises an exposure step of irradiating light based on information to form a latent image and a developing step of developing the latent image by heating, exposing the photoreceptor in a heated state. A characteristic image forming method is provided.

It is desirable that the temperature of the photosensitive member during the exposure is adjusted to be not lower than the glass transition point of the binder used and not higher than the melting point of the hot solvent used.

That is, the temperature of the photoconductor at the time of exposure is set to a temperature not lower than the glass transition point of the binder and not higher than the melting point of the thermal solvent to redisperse the reducing agent and toning agent localized during coating and storage. It is possible to increase the efficiency of generating a latent image generated by exposure.

When the temperature of the photoconductor during exposure is below the glass transition point of the binder, the localized reducing agent and toning agent are difficult to redisperse and the image characteristics are not improved. Further, when the temperature of the photoconductor becomes equal to or higher than the melting point of the hot solvent, the photosensitivity is lowered due to a change in the adsorption state of the silver halide and the sensitizing dye. Therefore, the temperature of the photoconductor during exposure is
Controlling the temperature above the glass transition point of the binder and below the melting point of the hot solvent is effective for improving sensitivity and achieving uniform sensitivity.

The photoconductor used in the present invention will be described below.

As the organic silver salt contained in the photoconductor used in the present invention, any known organic silver salt can be used, and those which are less likely to undergo adverse changes such as coloring under room light are preferable. Specifically, "Basics of Photographic Engineering" (1st edition, Corona Publishing Co., Ltd., edited by the Photographic Society of Japan, published in 1982) non-silver salt edition, p
247, organic silver salts and triazole silver salts described in JP-A-59-55429 and the like can be used, and silver salts having low photosensitivity are preferably used. For example, aliphatic carboxylic acid, aromatic carboxylic acid, thiol or α-
It is a silver salt such as a thiocarbonyl group compound having 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. Those having an appropriate carbon number (for example, those having a carbon number of 16 to 26) are preferable. Of these, behenic acid is particularly preferable.

Examples of aromatic carboxylic acids include benzoic acid derivatives, quinolinic acid derivatives, naphthalenecarboxylic acid derivatives,
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 and the like, U.S. Pat.
The mercapto compound described in No. 274 can be mentioned.

Examples of the compound containing an imino group include benzotriazoles or their derivatives described in JP-B-44-30270 or 45-18416, such as benzotriazole, methylbenzotriazole and other alkyl-substituted benzotriazoles, and 5-chlorobenzotriazole. Such as halogen-substituted benzotriazoles, butylcarbimide benzotriazoles and other carboimide benzotriazoles, nitrobenzotriazoles described in JP-A-58-18639, sulfobenzotriazole described in JP-A-58-115638, and carboxybenzo. Representative examples include triazole or a salt thereof, hydroxybenzotriazole and the like, 1,2,4-triazole and its derivative described in US Pat. No. 4,220,709. It can be.

The amount of the organic silver salt used ^{is, 0.3g / m 2 ~30g / m} 2 when prepared to the photoreceptor, in particular 0.7
g / m ^{2 to} 15 g / m ² , and further 1.2 g / m ² to 8
g / m ² is preferred. Also, with respect to 1 mol of the organic silver salt,
The silver halide is contained in an amount of preferably 0.001 to 2 mol, more preferably 0.05 to 0.4 mol. Further, the reducing agent is preferably 0.1 mol per mol of the organic silver salt.
05 mol to 3 mol, more preferably 0.2 mol to 1.3
Molar content.

As the reducing agent, a reducing agent capable of reducing an organic silver salt to produce silver when heated in the presence of silver nuclei produced by exposing a photosensitive silver halide is used.

Examples of such reducing agents include monophenols, bisphenols, trisphenols, tetrakisphenols, mononaphthols, bisnaphthols, dihydroxynaphthalenes, sulfonamidephenols, biphenols and trihydroxynaphthalenes. , Dihydroxybenzenes, trihydroxybenzenes, tetrahydroxybenzenes, hydroxyalkyl monoethers, ascorbic acids, 3-pyrazolidones, pyrazolones, pyrazolines, sugars, phenylenediamines, hydroxyamines, reductones, hydrooxa Examples thereof include mic acids, hydrazines, hydrazides, amidoximes, N-hydroxyureas and the like. Among these, p-bisphenols, o-bisphenols, bisnaphthols, 4-substituted naphthols and the like are particularly preferable.

Generally, developers used in ordinary silver halide light-sensitive materials, specifically hydroquinone, methylhydroquinone, chlorohydroquinone, methylhydroxynaphthalene, N, N'-diethyl-p-phenylenediamine, amino Phenol, dichloroaminophenol, ascorbic acid, 1-phenyl-3-pyrazolidone and the like can be mentioned. In addition to these, 2,2 '
-Methylenebis (6-t-butyl-4-methylphenol), 4,4'-butylidenebis (6-t-butyl-4)
-Methylphenol), 4,4'-thiobis (6-t-
(Butyl-3-methylphenol), etc., and further JP-A-4
Bisnaphthol-based reducing compounds described in JP-A-6-6074, 4-benzenesulfonamidephenol-based compounds described in Belgian Patent No. 802519, or JP-A-2-210352 and JP-A3-1.
The compound etc. which are described in 35564 can be mentioned.

Examples of the silver halide include silver chloride, silver bromide, silver iodide, silver iodobromide, silver iodochloride and silver iodochlorobromide. This silver halide, particularly fine particles are effective, as a method for preparing these,
A part of the non-photosensitive organic silver salt is a silver halide forming component such as ammonium bromide, lithium bromide, sodium chloride,
Examples thereof include a method of halogenating with N-bromosuccinimide or the like to prepare a fine silver halide, a method of containing a so-called external silver halide, and the like.

A dry silver salt photosensitive element containing this external silver halide is described in, for example, Belgian Patent No. 774436. That is, a photosensitive silver halide is prepared separately from the dry silver salt photosensitive element, in other words, in the absence of an organic silver salt and a reducing agent, and then the silver halide is added to an image forming component and mixed. It is prepared by In this case silver halide (or,
The preferable content of the (silver halide-forming component) is 0.001 to 0.5 mol, and particularly preferably 0.01 to 0.3 mol per mol of the organic silver salt.

The silver halide may have a cubic shape, an octahedral shape, a tabular shape or the like, and a cubic or tabular silver halide is particularly preferable. The length of one side of the cubic silver halide crystal is preferably 0.01 to 2 μm.
m, and more preferably 0.02 to 1 μm.

The average aspect ratio of tabular silver halide is preferably 100: 1 to 3: 1 and more preferably 5.
0: 1 to 5: 1 and the particle diameter is preferably 0.
It is from 1 to 2 μm, more preferably from 0.02 to 1 μm. These may be subjected to chemical sensitization as is done for ordinary photographic emulsions. That is, sulfur sensitization, noble metal sensitization, reduction sensitization and the like can be used. Moreover, you may perform optical sensitization.

As the optical sensitization, a method using a sensitizing dye can be applied. As the sensitizing dye, cyanine dyes, merocyanine dyes, xanthene dyes and the like are preferably used.

Further, the halogen composition in the grains may have a uniform or different multiple structure. As the photosensitive silver halide, two or more kinds of silver halides having different halogen compositions, grain sizes, grain size distributions and the like may be used in combination.

The binder used when the composition of the present invention is prepared into a photoreceptor is preferably a hydrophobic or hydrophilic polymer, and is preferably transparent or translucent. Specifically, polyvinyl butyral, cellulose acetate butyrate, polymethylmethacrylate, polyvinylpyrrolidone, ethyl cellulose, cellulose acetate, polyvinyl acetate, polyvinyl alcohol, gelatin, those having a sulfobetaine repeating unit described in Canadian Patent No. 774054. Etc. can be mentioned. The glass transition point of various binders depends on the molecular weight and the degree of polymerization of polyvinyl butyral, for example.
It can be appropriately selected from 0 ° C to 95 ° C. The amount of the binder used is preferably 10: 1 to 1:10 in weight ratio with respect to the organic silver salt. More preferably, it is in the range of 4: 1 to 1: 2. The binder may be contained in a single layer, but the long-chain fatty acid silver salt and the reducing agent may be formed in multiple layers as separate layers, or a long-chain fatty acid silver salt may be further formed on the upper surface or the lower surface of the single layer containing the above components. Alternatively, it may be a multilayer provided with a layer containing a reducing agent.

In addition to the above-listed compounds, the composition of the present invention further contains a polymerizable compound, a photopolymerization initiator or a thermal polymerization initiator, and a heat diffusible dye as a dry silver salt photosensitive element. Can be prepared into a silver salt photoreceptor.

As the polymerizable compound, a compound having at least one reactive vinyl group in one molecule can be used, and examples thereof include a reactive vinyl group-containing monomer, a reactive vinyl group-containing oligomer and a reactive vinyl group-containing monomer. One or more selected from the group consisting of polymers can be used.

As the reactive vinyl group of these compounds,
In addition to styrene-based vinyl groups, acrylic acid-based vinyl groups, methacrylic acid-based vinyl groups, allyl-based vinyl groups, vinyl ethers, ester-based vinyl groups such as vinyl acetate, substituted or non-substituted vinyl groups, etc. Can be mentioned.

In the silver salt photosensitive composition for dry development of the present invention, in addition to the above, a sensitizing dye, an anti-irradiation dye,
Development accelerators, other antifoggants and the like can be added. As the sensitizing dye, a cyanine dye, a merocyanine dye, a trinuclear dye and the like are preferably used, and examples thereof include 3,3 ′.
-Dicarboxyethyl-2,2-thiocarbocyanine iodide, 3,3'-diethyl-2,2'-thiacarbocyanine iodide, 3,3'-disulfoethyl-
2,2'-thiadicarbocyanine bromide, 3,3 '
A dye such as -diethyl-2,2'-thiatricarbocyanine iodide is preferably used.

The amount of the sensitizing dye added is 1 mol of silver halide.
Against 10^-FourMole to 2x10 ^-2In moles, preferably
Is 10^-3Mol to 10^-2It is a mole.

As the irradiation preventing dye, a styryl dye, an oxazole dye, a rhodamine dye or the like is used.

In the practice of the present invention, what can be used as a development accelerator includes an alkali generator and a color tone agent. As the alkali generator, alkali metal salts of organic acids, acid salts of organic bases and the like are used. As the color toning agent, the compounds described in "Basics of Photography Industry, Non-Silver Salt Edition", page 252, lines 4 to 7 are used, and phthalazines, phthalazinones, benzoxazinediones and the like are preferable.

In the dry silver salt photoreceptor of the present invention, a protective layer may be provided on a layer in which the above-mentioned various compounds are provided in a single layer or multiple layers. As the protective layer, various polymers are used,
Triacetate cellulose, diacetate cellulose,
Polyvinyl alcohol, gelatin, etc. are used.

In the present invention, the support of the photosensitive element may be a synthetic resin film of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, cellulose acetate or the like, synthetic paper, paper coated with a synthetic resin film of polyethylene or the like, art. Paper, paper such as photographic barrier paper, or metal plate (foil) such as aluminum,
By a usual method, a synthetic resin film having a metal vapor deposition film, a glass plate and the like can be mentioned.

Examples of the thermal solvent include aliphatic carboxylic acids, aromatic carboxylic acids, thiols, thiocarbonyl compounds having α-hydrogen, and imino group-containing compounds. As the aliphatic carboxylic acid, acetic acid (melting point 16.6
℃, the temperature in parentheses below indicates the melting point), butyric acid (-5.3
℃), succinic acid (188 ℃), sebacic acid (134
℃), adipic acid (153 ℃), oleic acid (13
C), linoleic acid (-5 C), linolenic acid (-11
℃), tartaric acid (205 ℃), palmitic acid (63 ℃),
There are stearic acid (72 ° C.), behenic acid (82 ° C.) and the like, but generally, the smaller the carbon number, the more unstable the silver salt.
Compounds having a range of 8) are preferred. Aromatic carboxylic acids include benzoic acid derivatives, xylinonic acid derivatives, naphthalenecarboxylic acid derivatives, salicylic acid derivatives, gallic acid (258 ° C), tannic acid, phthalic acid (234 ° C), phenylacetic acid derivatives, pyromellitic acid (279 ° C). ) Etc.

Examples of the thiocarbonyl compound having 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 and the like, U.S. Pat.
The mercapto compound described in No. 274 can be mentioned.

Examples of the compound containing an imino group include JP-B-44-30270 and JP-B-45-1841.
No. 6, benzotriazole or its derivatives, for example, alkyl-substituted benzotriazoles such as benzotriazole and methylbenzotriazole, halogen-substituted benzotriazoles such as 5-chlorobenzotriazole, and carboximidobenzotriazoles such as butylcarbimidobenzotriazole. , JP-A-58-118
639 gazette, nitrobenzotriazoles described in JP-A-58-115638, sulfobenzotriazole, carboxybenzotriazole or salts thereof, hydroxybenzotriazole, etc., described in U.S. Pat. No. 4,220,709. 2,4-triazole, 1H-tetrazole, carbazole, saccharin,
Representative examples include imidazole and its derivatives. These organic silver oxide compounds should occupy about 5 to 70% by weight of the image forming layer, but the ratio is preferably 10 to 60% by weight, more preferably 20% by weight.
˜55 wt%.

[0040]

The present invention will be described in detail below with reference to the drawings. <Embodiment 1> FIG. 1 is a schematic view illustrating an image forming method of the present invention. The optical system used in this image forming method is a semiconductor laser light source 1, a collimator lens 2, a polygon mirror 3 for beam scanning, and a focusing f-θ lens 1.
Consists of. Light having image information is applied to the film-shaped photoconductor 6 by this optical system. At this time, the temperature of the exposure supporting roll 5 is controlled by the heater 5a so that the exposure supporting roll 5 can be exposed at a desired temperature. The exposed photoconductor 6 is sent to the heat developing roll 8 by the carrying roll 7, where it is heat-developed by the sheet heating element 8a and an image is output.

The light-sensitive material used in this embodiment is a heat-developable photosensitive material containing silver halide as a main component. The sectional view is shown in FIG. Thickness 1 as support 20
80 μm polyethylene terephthalate was used. Two
Reference numeral 1 is an easy-adhesion layer for making it difficult for the support 20 and the photosensitive layer 22 to separate from each other, and an acrylic resin was used. Photosensitive layer 22
Has a thickness of about 10 μm and has the following composition.

Binder: Polyvinyl butyral 4.3 parts Silver halide: Silver bromide (particle size 60 Å) 0.3 parts Organic silver: Silver behenate 3.2 parts Thermal solvent: Behenic acid 1.6 parts Reducing agent: 2,2'-Methylenebis (6-t-butyl-4-methylphenol) 2.5 parts Toning agent: Phthalazinone 0.3 parts Fogging agent: Homophthalic acid 0.5 parts Sensitizing dye: Formula having the following structure [ Compound of I] 0.03 part However, the above-mentioned [part] indication shows the weight part (the following is the same).

[0043]

[Chemical 1] A protective layer 23 is made of polyvinyl alcohol and has a thickness of 2 μm.

This photoreceptor was exposed from the protective layer side.

The temperature of the photoconductor during exposure was controlled to 70 ° C. The glass transition point of polyvinyl butyral used as a binder is about 55 ° C, and the melting point of behenic acid used as a thermal solvent is about 82 ° C.

The photosensitive characteristics obtained under the above conditions are shown by the solid line in FIG. In FIG. D. Indicates optical density.

As comparative data, the temperature of the photoconductor is 30 ° C.
And the photosensitivity at 120 ° C. are also shown by the broken line and the dotted line, respectively.

The exposure conditions were as follows.

Semiconductor laser: oscillation wavelength 680 nm,
Power 2 mW (sensitive material surface) Beam diameter: 20 (main scanning direction) × 40 (sub scanning direction) μm Pixel clock: 6 MHz Resolution: 1200 dpi Thermal development was carried out at 120 ° C. for 10 seconds.

That is, by exposing and developing the temperature of the photoconductor at 70 ° C., which is a temperature not lower than the glass transition point of the binder and not higher than the melting point of the thermal solvent, it is necessary to start up the photoconductor (starting to increase the density). Exposure energy),
It can be seen that the maximum concentration is also rising. <Embodiment 2> The exposure unit shown in FIG.
Exposure was carried out while heating to ° C. In FIG. 4, the photoconductor is heated by the sheet heating element 10 via the black felt 11 for antireflection and heat diffusion. The photoconductors used in this example are as follows.

Support: PET (thickness 100 μm) Easy adhesion layer: Acrylic resin (thickness 5 μm) Composition of photosensitive layer: Binder: Polyvinyl butyral 4.3 parts Silver halide: Silver bromide (particle size 60 angstrom) 0.3 parts Organic silver: Silver stearate 3.2 parts Thermal solvent: Stearic acid 1.6 parts Reducing agent: 2,2'-methylenebis (6-t-burtyl-4-methylphenol) 2.5 parts Toning agent : Phtharazinone 0.3 part Antifoggant: Homophthalic acid 0.5 part Sensitizing dye: Compound of formula [II] having the following structure 0.03 part

[0052]

[Chemical 2] This photoreceptor was exposed from the protective layer side. The exposure conditions at this time are as follows.

Semiconductor laser: oscillation wavelength 780 nm,
Power 2 mW (sensitive material surface) Beam diameter: 17 (main scanning direction) × 35 (sub scanning direction) μm Pixel clock: 6 MHz Resolution: 1200 dpi Thermal development was conducted at 110 ° C. for 10 seconds.

The binder had a glass transition point of about 55 ° C., stearic acid used as a heat solvent had a melting point of about 72 ° C., and the temperature of the photoreceptor during exposure was set at 65 ° C. for exposure. , A good image was obtained.

[0055]

As described above, the sensitivity of the photoconductor is increased by setting the temperature at the time of exposure of the photoconductor to the glass transition point of the binder used for the photoconductor or more and the melting point of the thermal solvent or less, It also has the effect of becoming uniform. As a result, stable images can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating an image forming method for carrying out the present invention.

FIG. 2 is a cross-sectional view illustrating a photoconductor used in the present invention.

FIG. 3 is a graph illustrating a sensitivity curve obtained in Example 1.

FIG. 4 is a schematic diagram illustrating an exposure device used in Example 2.

[Explanation of symbols]

 1 Light Source 2 Collimator Lens 3 Polygon Mirror 4 f-θ Lens 5 Exposure Support Roll 5a Heating Heater 6 Photoreceptor 7 Conveyor Roll 8 Thermal Development Roll 8a Sheet Heater 9 Photoreceptor Supply Roll 10 Sheet Heater 11 Felt 12 stage 13 stage feed motor 14 mirror 20 support 21 easy adhesion layer 22 photosensitive layer 23 protective layer

Claims (2)

[Claims] 1. A photoreceptor having a heat-developable photosensitive layer containing at least an organic silver salt, a photosensitive silver halide, a reducing agent, a thermal solvent and a binder on a support is irradiated with light based on image information. An image forming method comprising an exposure step of forming a latent image and a developing step of developing the latent image by heating the latent image, wherein the photosensitive member is exposed in a heated state. 2. The image forming method according to claim 1, wherein the temperature of the photosensitive member at the time of exposure is not lower than the glass transition point of the binder used and not higher than the melting point of the hot solvent used.