JPH06242562A - Color image forming method - Google Patents

Abstract

(57) [Summary] [Structure] The color image forming method of the present invention uses ink particles for electrostatic latent image development containing a photosensitive silver halide which is sensitive to light of a specific wavelength, and Fixing is performed while applying a releasable solution containing an antioxidant or an acid anhydride, and a silver adsorbent and a silver complex chloride agent to the electrostatic latent image developing ink particles. [Effect] Since a photosensitive silver halide is used,
The exposure energy can be reduced and the apparatus can be downsized. In addition, by incorporating the above-mentioned fixing step, unreacted photosensitive silver halide, organic silver salt and dye precursor, and reduced silver produced by color exposure and heating are converted into an inactive compound, so that storage It is possible to provide a color image forming method in which discoloration of an inner color image does not occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming method by electrophotography using an electrostatic latent image,
The present invention relates to a color image forming method for forming a color image by developing and transferring substantially once.

[0002]

2. Description of the Related Art Conventionally, a color image forming method using an electrostatic latent image includes a step of forming a latent image on a latent image carrier, a step of developing a latent image with color toner to visualize it, and a toner The step of transferring onto a recording medium or an intermediate transfer medium has been repeated 3 or 4 times (hereinafter referred to as a multiple transfer system). Also, as another method, JP-A-63-1397
No. 34, U.S. Pat. No. 4,654,282, etc., the latent image forming step and the developing step are repeated three or four times on the latent image carrier (hereinafter, Multiple development method). However, there is a problem in that the color image is apt to be disturbed in a plurality of transfer steps in the multiple transfer method and in a plurality of development steps in the multiple development method. Furthermore, in any of the above methods, it is necessary to install a large number of developing devices in the image forming apparatus, which hinders downsizing of the image forming apparatus.

Further, Japanese Patent Laid-Open No. 63-311364,
JP-A-2-157768, US Pat. No. 5,04
No. 5,420, Japanese Patent Application Laid-Open No. 3-229262, a process of forming an electrostatic latent image, a process of developing with developer particles that develop or decolor in different colors depending on the wavelength of irradiation light, A method including a step of exposing a visible image particle to form a desired color image has been proposed (hereinafter, referred to as a one-time developing method). In the one-time development method, a color image can be substantially formed by one-time development and transfer by electrophotography. Therefore, there is an advantage that a high-quality color image can be formed without color misregistration, and the image forming apparatus can be simplified and downsized.

Further, in JP-A-48-75223 and JP-A-57-212426, a photosensitive silver halide salt which absorbs light of a specific wavelength to form a color latent image, A photothermographic color image forming method has been proposed in which an organic silver salt, a dye precursor or the like is used as a photothermographic material, and a color is developed in a desired color tone by heating after color exposure. This method has a feature that a full-color image can be formed by performing color exposure and heating once, and all the steps can be performed by a dry method.

Further, as a method for preventing discoloration of the photothermographic material when left in the bright place, Japanese Patent Laid-Open No. 48-452.
No. 28, etc. propose a method of using a photosensitive halogenating agent that converts reduced silver produced during exposure by light exposure and color development by heating to a photosensitive silver halide salt. As another method, a method of applying a stabilizing solution containing a silver complex chlorinating agent that inactivates a photosensitive silver halide salt and an organic silver salt is disclosed in JP-B-46-5393 and JP-A-51-51. 1
It is proposed in the specification of 04826.

[0006]

As described above, the one-time development method has an advantage that a high quality color image can be formed and the image forming apparatus can be downsized as compared with the multiple transfer method and the multiple development method. However, according to the knowledge of the present inventor, there are the following essential problems.

Japanese Patent Laid-Open No. 63-311364,
JP-A-2-157768, US Pat. No. 5,04
According to the description in Japanese Patent No. 5,420, coloring or erasing of the image-developing particles is performed only by exposure energy.
Therefore, a relatively large exposure apparatus is required, and if the exposure apparatus is also cooled, there is a problem that miniaturization of the apparatus is substantially prevented.

Further, the above-mentioned Japanese Patent Application Laid-Open No. 3-229262 discloses a method of using developer particles made of the photothermographic material. This method has a high photosensitivity because the image-forming particles have a photosensitive silver halide and can reduce the exposure energy, and there are image-forming particles in the non-image area. Not visible particles,
That is, the consumption of the photothermographic material can be reduced. But,
A color image using the photothermographic material has a problem in that it develops or changes color during storage. The cause of this is, for example, yellow (hereinafter referred to as Y), magenta (hereinafter referred to as M), and cyan (hereinafter referred to as C), except that the color is changed to black after color exposure and heating. In the colored portion, the photosensitive silver halide salt, the organic silver salt and the dye precursor which did not react due to the non-color exposure remain, and in the black or Y, M and C colored portions. This is because the reduced silver produced by color exposure and heating remains. Specifically, when the color image is left in the light, discoloration occurs due to photoreduction of the remaining photosensitive silver halide salt to produce brown or black reduced silver, and further during long-term storage of the color image, This is because the remaining organic silver salt and dye precursor undergo a redox reaction due to the catalytic action of reduced silver, and the color-forming reaction in which the dye precursor becomes a dye proceeds even at room temperature. Therefore, there is a problem in that the storage stability of a color image cannot be obtained by the above-described one-time development method.

Prior art for solving this problem is disclosed in Japanese Patent Laid-Open No. 48-52228 and Japanese Patent Publication No. 46-539.
No. 3, Japanese Patent Laid-Open No. 51-104826, and the like.

The method described in Japanese Patent Application Laid-Open No. 48-45228 discloses a method of using a photosensitive halogenating agent which emits halogen upon exposure to light, and reduced silver produced during exposure to light and color development by heating. Discoloration is prevented by using a photosensitive silver halide. However, in this method, since the photosensitive halogenating agent is sequentially consumed, when it is exhausted, the photosensitive silver halide salt is exposed to light to produce brown or black reduced silver, resulting in discoloration of the image. This also occurs, and this also catalyzes the coloring reaction of the dye precursor to cause coloration / discoloration of the stored image, which makes it difficult to store the image for a long time.

The methods described in Japanese Patent Publication No. 46-5393 and Japanese Patent Application Laid-Open No. 51-104826 described above are such that a photosensitive silver halide salt and organic silver are dissolved in a solvent such as water or alcohol. A stabilizing solution in which a silver complex chlorinating agent for complexing silver ions of salt is dissolved is applied to a color image to complex silver ions to prevent discoloration when left in the light. However, this method requires a separate solvent removing step, and thus has a problem in that the apparatus cannot be downsized.

Further, in any of the above-mentioned methods, only the discoloration of the photosensitive silver halide salt and the organic silver salt due to being left in the bright place is prevented, and the remaining reduced silver remains. It does not prevent the reaction that catalyzes the coloring reaction of the dye precursor. Therefore, there is a problem in that long-term storage stabilization of a color image cannot be realized by either method.

Therefore, the present invention solves the problems of these prior arts, and a high-quality color image that does not deteriorate even after long-term storage can be obtained, and a color image that can be downsized at low running cost. It is intended to provide a forming method.

[0014]

The color image forming method of the present invention comprises a photosensitive silver halide salt which absorbs light of a specific wavelength to form a color latent image and a silver ion which is heated to reduce silver ions. In a color image forming method using an electrostatic latent image developing ink particle containing a dye precursor that oxidizes and develops color, in the step of developing a color latent image generated by color exposure to a desired color tone by heating. Then, amines,
At least one silver adsorbent selected from quinones and phenols and compounds having a skeleton structure of any of colorless antioxidants, triazole, benzimidazole, mercaptotetrazole, and tetraazaindene, both before and after oxidation. While supplying a releasable solution in which at least one silver complex chlorinating agent selected from compounds having a functional group of alkylthioureas and thionamide is dissolved from the heat and pressure supplying member to the electrostatic latent image developing ink particles. It is characterized in that heat and pressure are applied at the same time to perform heat fixing on the recording medium.

Further, the color image forming method of the present invention comprises a photosensitive silver halide salt which absorbs light of a specific wavelength to form a color latent image and a dye precursor which develops a color while reducing silver ions by heating. In the color image forming method using the electrostatic latent image developing ink particles containing, following the step of developing a color latent image generated by color exposure to a desired color tone by heating, an acid anhydride, an aldehyde, At least one color-free coupler selected from compounds having a functional group of either isocyanate or epoxy, triazole, benzimidazole, mercaptotetrazole,
Dissolved at least one silver adsorbent selected from compounds having a skeleton structure of tetraazaindene, and at least one silver complex chlorinating agent selected from compounds having functional groups of alkylthioureas and thionamides It is characterized in that heat and pressure are applied at the same time to perform thermal fixing on the recording medium while supplying the releasing solution from the thermal pressure supplying member to the ink particles for electrostatic latent image development.

[0016]

The present invention comprises a photosensitive silver halide salt capable of obtaining high sensitivity to form a color latent image by color exposure, a color image by heating, an antioxidant or a non-coloring coupler, and silver adsorption. Agent, silver complex chlorination agent, unreacted photosensitive silver halide salt, organic silver salt and dye precursor, reduced silver produced by color exposure and heating is converted to an inactive compound for electrostatic latent image visualization Ink particles are used to form a color image by an electrostatic latent image forming step, a developing step, a color latent image forming step, a transferring step, a heat developing step, and a fixing step.

Further, a releasable solution containing an antioxidant or a non-color coupler, a silver complex chlorinating agent, and a silver adsorbent is added from the heat and pressure member to the electrostatic latent image developing ink particles in association with the fixing step. , The photosensitive silver halide, the organic silver salt, the reduced silver, and the dye precursor are all converted into inactive compounds after the color image formation. Therefore, the present invention makes it possible to obtain a high-quality color image which does not deteriorate even after long-term storage, and substantially uses an electrophotographic method by using the photothermographic material as a material for electrostatic latent image developing ink particles. By performing color image formation by developing and transferring once, the exposure energy can be reduced and the apparatus can be downsized.

In electrophotographic toner fixing, a releasable solution is generally supplied in order to prevent fusion of the molten toner and the heat and pressure supply member. Colorless couplers selected from the above-mentioned amines, quinones, phenols and colorless antioxidants before or after oxidation or compounds having any functional group of acid anhydride, aldehyde, isocyanate and epoxy. , A silver adsorbent selected from compounds having a skeleton structure of any one of triazole, benzimidazole, mercaptotetrazole, and tetraazaindene, and a silver complex chlorinating agent selected from a compound having a functional group of alkylthioureas and thionamide By using the releasing solution, the photosensitive silver halide, the organic silver salt, the reduced silver and the dye precursor can be converted into an inactive compound, and the solvent need not be removed after the conversion. The long-term storage stability of the color image can be realized without losing the merit of the dry method.

The present invention will be described in detail below with reference to examples.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic view of an apparatus using the color image forming method of the present invention. An apparatus using the color image forming method of the present invention includes a charging unit 1, an image exposing unit 2, a developing unit 3, a color exposing unit 4, a transfer unit 5, a heat developing unit 6, a fixing unit 7, a cleaning unit 8 and a latent image. It comprises a carrier 9. The process of forming a color image using this apparatus is as described below.

As the latent image carrier 9, selenium, selenium-
Tellurium, arsenic-selenium, cadmium sulfide, zinc oxide, titanium oxide, inorganic electrophotographic photoreceptors such as amorphous silicon, polyvinylcarbazole, phthalocyanine, azo pigments, hydrazine, phenylamine and the like containing organic electrophotographic photoreceptor, or The dielectric layer used in the ionography method can be used in the form of a drum or sheet. The latent image carrier 9 is charged by the charging means 1 to perform uniform charging. Here, a corona charger, a charging roller, or the like can be used as the charging unit 1 and the transfer unit 5 described later, but since the material of the electrostatic latent image developing ink particles 10 is easily deteriorated by ozone, the charging roller or the like is used. It is more preferable to use the device aiming at ozone-free.

In the case of electrophotography, the image exposure means 2 performs image exposure of a color image with a laser diode (hereinafter referred to as LD), a liquid crystal shutter (hereinafter referred to as LCS), an LED and the like. The light carriers are generated by the exposure to cancel the charged electric charge, and an electrostatic latent image composed of a charged portion and a charge disappeared portion formed by the exposure is formed. Image exposure is exposure that includes a binary signal indicating only the presence or absence of an image or a signal indicating the gradation of an image. The exposure of the binary signal is performed by turning on / off the light irradiation by the image exposure unit 2. The exposure including the signal indicating the gradation of the image is performed by controlling the exposure time per pixel, the exposure intensity, and the number of exposure pulses. Further, in the ionography method, an electrostatic latent image is formed by controlling the ion flow from the ion flow electrode.

The developing means 3 attaches the charged electrostatic latent image developing ink particles 10 to the charge disappearing portion on the latent image carrier 9 to visualize the latent image to form a preliminary developing image. To do. Ink particles 10 for electrostatic latent image development used here
Is a toner characteristic used in a latent image recording method such as an electrophotographic method or an ionography method, and has a characteristic that a desired color tone is developed by color exposure by a color exposure unit 4 and heating by a thermal development unit 6 described later. Yes, it is exposed to light of a specific wavelength, for example, red (hereinafter, R), green (hereinafter, G), or blue (hereinafter, B), which are three primary colors for additive color mixing. In addition, ink particles for electrostatic latent image development that heat and develop any of the three primary colors Y, M, and C for subtractive color mixing are used for three colors.
In this case, if the combination of photosensitivity and coloring is (sensitized color, developed color), (R, C), (G, M),
(B, Y), and these three types of ink particles for electrostatic latent image development are uniformly mixed and used for development.

Color exposure of the color image is performed on the preliminary visible image by the color exposure means 4. In the color-exposed preliminary development image, only the electrostatic latent image development ink particles 10 having sensitivity to the wavelength of the color exposure form a color latent image. Color exposure means 4
The exposure device used in the electrophotographic method of the device used in the image exposure device 2 can be used in the same manner as the device used for the image exposure device 2, but it emits light at three different wavelengths in order to include a color signal in the exposure. It is composed of an LD, an LED, and an LCS that is a combination of three color filters.

The transfer means 5 applies a charge having a polarity opposite to that of the electrostatic latent image developing ink particles 10 from the back surface of the recording medium 11 by a charging means such as a corona charger or a charging roller, and transfers it by using electrostatic attraction. I do. Regarding the transfer timing, there are the following two methods. First, there is a case where an inorganic / organic electrophotographic photoreceptor is used as the latent image carrier 9. In this case, the electrostatic latent image developing ink particles 10 are transferred onto the recording medium 11 before being subjected to color development by heating by the heat developing means 6 described later. The other is a case where a dielectric layer for an ionography method is used as the latent image carrier 9. In this case, the heat developing means 6 described later is arranged between the color exposing means 4 and the transferring means 5, and the electrostatic latent image developing ink particles 10 are provided.
After heat-developing the latent image on the latent image carrier 9, the recording medium 11
Transfer to the top.

The heat developing means 6 is carried out by heating from the back surface of the recording medium 11 using a heat roller, a halogen lamp or the like, and heats the electrostatic latent image developing ink particles 10 on the recording medium 11 to obtain a desired image. Makes the color develop. At this time, only the electrostatic latent image developing ink particles 10 on which the color latent image is formed develops color, and the preliminary developing image becomes a color image.

The fixing means 7 is, more specifically, the releasable solution 15
It comprises a releasable solution supply means 12 such as felt impregnated with, a heat roller 13, and a pressure roller 14. The schematic diagram is shown in FIG. The releasable solution 15 is supplied to the electrostatic latent image developing ink particles 10 from the releasable solution supply means 12 via the heat roller 13 of the heat pressure applying member. Then, the photosensitive silver halide salt, the organic silver salt, the reduced silver, and the dye precursor are converted into an inactive compound to prevent the subsequent redox reaction. At the same time, the heat roller 13 and the pressure roller 14 simultaneously apply heat and pressure to melt and bond the ink particles 10 for electrostatic latent image development. Further, the releasing solution 15 prevents offset of transfer of a part of the electrostatic latent image developing ink particles 10 to the heat roller 13 during fixing.

Here, the devices used for the heat developing means 6 and the fixing means 7 may be the same. A schematic diagram thereof is shown in FIG. A heat roller or the like used in the heat developing unit 6 is used as the heat roller 13 of the fixing unit 7, and the releasable solution supply unit 12 is arranged on the pressure roller 14.
Further, the heat roller 13 is replaced with the pressure roller 1.
When the recording medium 11 is made larger than 4, the electrostatic latent image developing ink particles 10 are heated and colored before the recording medium 11 contacts the heat roller 13 and the pressure roller 14. Since the releasable solution 15 attached to the roller 13 is removed by the cleaning pad 16 made of felt or the like, a color image can be formed without competition between heat coloring and inactivation. As described above, the color development of the ink particles 10 for electrostatic latent image development on which a color latent image is formed is performed by heating, the subsequent thermal pressure fixing on the recording medium 11, and the releasable solution 15 via the pressure roller 14. Can be applied by the same apparatus, and by consolidating the heat sources into one unit, the power consumption can be reduced and the image forming apparatus can be further downsized.

The electrostatic latent image developing ink particles 10 used in the present invention are toner materials used in a latent image recording method such as a conventional electrophotographic method, an ionography method, a magnetography method, and the like. -75223 publication,
It can be prepared by combining the photothermographic materials described in JP-A-57-212426, etc., but the material and toner composition of the ink particles for electrostatic latent image development are optimum for the present invention. The manufacturing method is as follows.

The electrostatic latent image developing ink particles are composed of a photosensitive silver halide salt, a wavelength sensitizing dye, an organic silver salt, a dye precursor, a charge control agent, a flow control agent and a binder resin.

As the photosensitive silver halide salt, single crystals of silver chloride, silver bromide, silver iodide, and mixed crystals thereof are used.
Further, gold-sensitized or sulfide-sensitized crystals can also be used. It is also possible to synthesize and use it on the surface of an organic silver salt as described in JP-A-48-45228.

The wavelength sensitizing dye is added in order to impart photosensitivity to light other than the light-sensitive wavelength unique to the photosensitive silver halide, and a cyanine or merocyanine dye can be used. Specifically, cyanine dyes, merocyanine dyes, styryl dyes, hemicyanine dyes, triphenylmethane dyes, xanthene dyes, and oxonol dyes can be used. Wavelength sensitization is performed by mixing a dye solution in which these dyes are dissolved with a photosensitive silver halide salt and adsorbing the dye on the surface of the photosensitive silver halide salt crystal.

As the organic silver salt, fatty acid silver salts such as silver stearate and silver behenate, and imino silver compounds such as saccharin silver and phthalazinone silver can be used. The fatty acid silver salts can also be used as a mixture with the same type of fatty acid.

The dye precursor is a material that oxidizes itself by causing an oxidation-reduction reaction with an organic silver salt by heating in the presence of reduced silver produced by color-sensitizing a photosensitive silver halide salt. Oxidative coloring leuco dye, which oxidizes to develop its own color,
Alternatively, a secondary color-developing agent comprising a reducing agent and a color coupler, which are oxidized to form a dye by coupling reaction with the color coupler, is used.

The coloring mechanism when an oxidative coloring leuco dye is used as the dye precursor is as follows. First, when color exposure corresponding to a color image is performed by the color exposure means 4, the photosensitive silver halide salt is exposed to light having a specific wavelength and photoreduced to produce reduced silver. Then, when it is heated together with the organic silver salt by the heat developing means 6, a redox reaction occurs between the organic silver salt and the oxidative color forming leuco dye by using the produced reduced silver as a catalyst, and the oxidative color forming leuco dye is oxidized to give a dye. And develop color. The mechanism proceeds as shown below. Silver ions released from the organic silver salt are adsorbed on the reduced silver to form silver ion clusters. The silver ion clusters are reduced by the reduction of the oxidative coloring leuco dye, and the oxidative coloring leuco dye itself is oxidized to become a dye. In this manner, the adsorption of silver ions on the reduced silver and the redox reaction of the oxidative coloring leuco dye occur repeatedly, and the dyes are sequentially produced to color the electrostatic latent image developing ink particles 10. The color development reaction that occurs in this step does not proceed because only the color-exposed ink particles proceed, and the ink particles that are not color-exposed do not generate reduced silver that adsorbs silver ions. As the oxidative color-forming leuco dye exhibiting the above-mentioned reaction, a reduced form (leuco form) of a thiazine-based, oxazine-based, indoaniline-based, diazine-based, lactone-based, diphenol-based, or benzylidene-based dye can be used.

The coloring mechanism when a secondary color developing agent comprising a reducing agent and a color forming coupler is used as a dye precursor will be described below. First, when color exposure corresponding to a color image is performed by the color exposure means 4, the photosensitive silver halide salt is exposed to light having a specific wavelength and photoreduced to produce reduced silver. Thereafter, the heat developing means 6 together with the organic silver salt is used.
When heated with, a redox reaction occurs between the organic silver salt and the reducing agent using the produced reduced silver as a catalyst to oxidize the reducing agent. Subsequently, the oxidized form of the reducing agent undergoes a coupling reaction with the color-forming coupler to form a dye and develop color. The mechanism described above proceeds as follows. Silver ions released from the organic silver salt are adsorbed on the reduced silver to form silver ion clusters. When the reducing agent reduces this, the silver ion clusters are reduced and the reducing agent itself is oxidized. Then, the coupling reaction with the color forming coupler,
It forms a pigment and develops color. In this manner, the adsorption of silver ions on the reduced silver and the redox reaction of the reducing agent repeatedly occur, and the dyes are sequentially produced to develop the electrostatic latent image developing ink particles. The color development reaction that occurs in this step does not proceed because only the exposed ink particles proceed, and the unexposed ink particles do not generate reduced silver that adsorbs silver ions. As the reducing agent for the secondary color developing agent exhibiting the above-mentioned reaction, p is
Derivatives of phenylenediamine and derivatives of p-aminophenol can be used. As the color coupler, an acylacetylamide type, a pyrazolane type, an indazolone type, a phenol type, a naphthol type, a hydroxynaphthamide type or the like can be used.

The charge control agent is added in order to control the chargeability of the ink particles for electrostatic latent image development and to stably perform preliminary development image formation. Organic metal complex salts, organic salts such as alkylammonium salts, and high molecular weight carboxylic acids can be used. However, since they function on the surface of the ink particles for electrostatic latent image development, they function as photosensitive silver halide salts and wavelength sensitization. It is selected from those having high transparency so as not to impair the photosensitivity of the dye.

The flow control agent is used for controlling / improving the flowability of the ink particles for electrostatic latent image development, and includes titanium oxide, oxides such as silica, nitrides, sulfides, polyfluorovinylidene, etc. Fine powder of fluororesins is used.

The binder resin is used for mixing and binding the above-mentioned materials, and is a vinyl ester derivative polymer such as polyvinyl acetate or vinyl polypropionate, methyl polyacrylate, butyl polyacrylate, polymethacryl. Methyl acid, polybutyl methacrylate, polyacrylonitrile, polyacrylamide and other acrylate and methacrylate derivative polymers, polystyrene, styrene derivative polymers such as polydivinylbenzene, polyvinyl ether, polyvinyl ether and other vinyl ether polymers, polyvinyl methyl ketone , Vinyl methyl ketone polymers such as polyvinyl methyl ethyl ketone, addition-polymerization polymers such as polyvinyl pyrrolidone, and nitrogen-containing vinyl derivative polymers such as polyvinyl indole, and these 2
Copolymers, cross-linked products, and mixtures of at least one kind are used. Furthermore, condensation-type polymers such as polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate, polyurethane resins and epoxy resins, and these 2
It is possible to use one or more copolymers, cross-linked products and mixtures.

The composition of the electrostatic latent image developing ink particles is particles having a particle size of 1 to 50 μm, preferably 5 to 25 μm, in which the above materials are dispersed in a binder resin.

The electrostatic latent image developing ink particles can be produced by applying a method known as a method for producing an electrophotographic toner. For example,
A method of dispersing and kneading the material of the ink particles for electrostatic latent image development in a solvent in which a binder resin is dissolved, and removing the solvent by a drying method such as spray drying to form a powder. A method in which the material of the ink particles for image formation is dispersed in a monomer solution of a binder resin, fine particles having a particle size of several μm are synthesized by a dispersion polymerization method, and the fine particles are aggregated to a predetermined particle diameter by a granulation method. And the like.

The releasing solution of the present invention comprises at least one releasing agent selected from an antioxidant or a colorless coupler, a silver complex chlorinating agent, a silver adsorbent and a polysiloxane, a halogen-modified polysiloxane, glycerin and a wax. It consists of molds.

When the antioxidant is present together with the unreacted oxidative coloring leuco dye, it oxidizes itself more rapidly than the oxidative coloring leuco dye and prevents the oxidative coloring of the oxidative coloring leuco dye. It is selected from the group consisting of quinones, quinones, and phenols that are colorless both before and after oxidation.
Specifically, phenyl-α-naphthylamine, phenyl-
β-naphthylamine, N, N′-diphenyl-p-phenylenediamine, N-phenyl-N′-cyclohexyl-p-phenylenediamine, N-isopropyl-N′-
Amines such as phenyl-p-phenylenediamine,
Quinones such as 2,5-t-butylhydroquinone, 2,
6-di-t-butyl-p-cresol, styrenated phenol, 2,2'-methylenebis- (4-methyl-6-
There are phenols such as t-butylphenol).

The non-color-developing coupler is a compound which is separately bonded to the unreacted reducing agent and the color-forming coupler to prevent color formation due to the coupling reaction between the reductant and the color-forming coupler.
Among the color-free couplers, as reducing agents, there are isocyanates such as hexamethylene diisocyanate and tolylene diisocyanate, and epoxies such as epoxyethylbenzene, epoxyoctadecane, epoxyoctane, and N- (2,3-epoxypropyl) phthalimide. ,
For color couplers, there are acid anhydrides such as phthalic anhydride, trimellitic anhydride and propionic anhydride, and aldehydes such as benzyl aldehyde and salicyl aldehyde.

The silver complex chlorinating agent is a compound for complexing silver ions of photosensitive silver halide salts and organic silver salts to convert them into inactive compounds, and is selected from compounds having a functional group of alkylthioureas and thionamide. To be done. For more information,
N, N'-dibutylthiourea, 1,3-diethyl-2-
Thiourea, N, N'-diisopropylthiourea, 1,3
-Dimethylthiourea, benzotriazole-2-thione, 4-methyl-4-thiazolin-2-thione, triazolidine-2-thione and the like.

The silver adsorbent adsorbs on the surface of reduced silver produced by color exposure and heating to convert the reduced silver into an inactive compound, and includes triazole, benzimidazole,
It is selected from compounds having a skeleton structure of either mercaptotetrazole or tetraazaindene. Specifically, benzotriazole, nitrobenzimidazole,
1-phenyl-5-mercaptotetrazole, 7-hydroxy-5-alkyl-1,3,4,7a-tetraazaindene and the like.

The releasable solution is prepared by mixing a silver complex chlorinating agent, a silver adsorbent and an antioxidant, or a silver complex chlorinating agent, a silver adsorbent and a colorless coupler with a release agent. It is desirable that the silver complex chloride agent, the silver adsorbent, the antioxidant and the colorless coupler are dissolved in a release agent, but if they are melt-mixed with the electrostatic latent image developing ink particles, the release agent is used. It is also possible to use it by uniformly dispersing it in the agent.

The present invention will be described in more detail by the following examples.

[Example 1] (Preparation of ink particles for developing electrostatic latent image) 50 g of a silver behenate / behenic acid (molar ratio 1: 1) mixture and 1500 g of a toluene / methyl ethyl ketone mixed solution (weight ratio 1: 1) Calcium bromide / methanol (5% solution) in a dispersion consisting of
A silver behenate / silver bromide dispersion was prepared by adding 10 ml. 0.5 ml of rhodanine / methanol (0.1% solution) as a merocyanine R wavelength sensitizing dye was added to this dispersion liquid.
100 g of polyester resin, 35 g of benzoylleucomethylene blue which is an oxidative coloring leuco dye as a C coloring dye precursor, and 0.5 ml of nickel nitrate / methanol (1%) as an oxidation aid of a dye precursor were sequentially added while being dissolved. Further, it was dried and pulverized by a spray drying method.

2 g of zinc stearate as a charge control agent,
The whole amount of the fine powder was added to a dispersion solution of 48 g of polyvinyl butyral and 2000 g of methanol and dried by a spray dry method.
(3 nm) was externally added and classified by a mechanochemical method to prepare ink particles for electrostatic latent image development.

By the same manufacturing method, ink particles for electrostatic latent image development comprising a G wavelength sensitizing dye and an M coloring oxidative coloring leuco dye, and a static image comprising a B wavelength sensitizing dye and a Y coloring oxidative coloring leuco dye. Ink particles for developing a latent image were prepared.

These three types of ink particles were uniformly mixed, and an electrostatic latent image developing ink particle mixed powder for forming a full-color image by exposing to the entire wavelength region of visible light was prepared.

The above-mentioned preparations were all carried out under a safe light in which silver bromide sensitized by wavelength was not exposed.

(Preparation of Releasing Solution) As a material for the releasing solution, a silver complex chlorinating agent, a silver adsorbent, an antioxidant and a releasing agent were used. 20 g of N, N′-diisopropylthiourea as a silver complex chloride agent and benzotriazole 20 as a silver adsorbent
g, 20 g of hydroquinone as an antioxidant and 1000 g of a polysiloxane phenyl derivative as a releasing agent were mixed, and then dispersed and dissolved by a ball mill to prepare a releasing solution.

A color image was formed according to the image forming method shown in FIG. 1 using the electrostatic latent image developing ink particle mixed powder and the releasing solution prepared as described above.

The color image thus obtained was allowed to stand on a surface of the image under a fluorescent lamp of 500 lux for 3 months, and the degree of discoloration was examined. The effect of inactivating the silver halide salt, the organic silver salt, the reduced silver and the oxidative coloring leuco dye was confirmed.

Comparative Example 1 Using the three types of electrostatic latent image developing ink particles prepared in Example 1, a color image was formed according to the image forming method shown in FIG. However, only the releasing agent was used in the releasing solution used in the fixing step.

The color image thus obtained was left under a fluorescent lamp of 500 lux for 3 months on the image surface, and the degree of discoloration was examined.
It turned brown.

Example 2 (Preparation of Ink Particles for Developing Electrostatic Latent Image) Three types of ink particles for developing electrostatic latent image were prepared with the same composition as in Example 1.
However, a secondary color developing agent comprising a reducing agent and a color forming coupler was used as the dye precursor. As the reducing agent, p-phenylenediamine, as the color-forming coupler, α-acylacetamides for Y color development, and for M color development, 5-
Pyrazolones and α-naphthols for C color development were used.

The three types of electrostatic latent image developing ink particles thus obtained are uniformly mixed and exposed to the entire wavelength region of visible light to form a full-color image. An ink particle mixed powder for use was prepared.

(Preparation of Releasing Solution) As a material for the releasing agent solution, a silver complex chlorinating agent, a silver adsorbent, a colorless coupler and a releasing agent were used. 1,3-Diethyl-2-silver complex chloride
Thiourea 20 g, 1-phenyl-5-mercaptotetrazole 20 g as a silver adsorbent, epoxy octadecane 30 g as a non-coloring coupler for a reducing agent, phthalic anhydride 15 g and benzyl aldehyde 5 g as a non-coloring coupler for a color forming coupler, release Using 1000 g of the polysiloxane phenyl derivative as an agent, these were mixed, and then dispersed and dissolved by a ball mill to prepare a releasable solution.

A color image was formed according to the image forming method shown in FIG. 1 using the electrostatic latent image developing ink particle mixed powder prepared as described above and the releasing solution.

The color image thus obtained was allowed to stand on the surface of the image under a fluorescent lamp of 500 lux for 3 months and the degree of discoloration was examined. The effect of deactivating the silver halide salt, the organic silver salt, the reduced silver, the reducing agent and the color forming coupler was confirmed.

Comparative Example 2 Using the three types of electrostatic latent image developing ink particles prepared in Example 2, a color image was formed according to the image forming method shown in FIG. However, the releasing solution used in the fixing step was the same as in Comparative Example 1.

The color image thus obtained was left under a fluorescent lamp of 500 lux on the image surface for 3 months, and the degree of discoloration was examined.
It turned brown.

[0066]

As described above, according to the present invention, a photosensitive silver halide salt that absorbs light of a specific wavelength to form a color latent image and a silver ion is reduced by heating to oxidize itself. In the color image forming method using the electrostatic latent image developing ink particles containing a dye precursor that develops color, the step of developing the color latent image generated by color exposure to a desired color tone by heating is continued. At least 1 selected from amines, quinones, phenols and compounds having a skeleton structure of any one of colorless antioxidants, triazole, benzimidazole, mercaptotetrazole, and tetraazaindene, both before and after oxidation.
Ink for developing an electrostatic latent image from a heat pressure supply member with a releasable solution containing at least one silver complex chlorinating agent selected from compounds having functional groups of silver adsorbents, alkylthioureas and thionamides While supplying heat to the grains, heat and pressure are applied at the same time to perform heat fixing on the recording medium, or a photosensitive silver halide salt that absorbs light of a specific wavelength to form a color latent image and silver ions by heating. In a color image forming method using an electrostatic latent image developing ink particle containing a dye precursor that develops a color while reducing, a step of heating the color latent image generated by color exposure to a desired color tone Then, at least one color-free coupler selected from compounds having a functional group of any one of acid anhydride, aldehyde, isocyanate, and epoxy, the silver adsorbent, and the silver complex. By supplying heat and pressure to the recording medium at the same time while supplying the releasing solution in which the agent is dissolved to the ink particles for electrostatic latent image development from the heat and pressure supplying member, the electrostatic latent image is formed. Since the photosensitive silver halide is used for the ink particles for image development, the exposure energy can be reduced and the apparatus can be downsized. Further, a step of fixing the electrostatic latent image developing ink particles on the recording medium while applying a releasing solution containing the antioxidant or the non-color-forming coupler, the silver complex chloride agent and the silver adsorbent. Incorporation converts unreacted photosensitive silver halide salt, organic silver salt and dye precursor, and reduced silver produced by color exposure and heating into an inactive compound, so that the color image can be stored even after long-term storage. It has become possible to provide a color image forming method in which discoloration does not occur.

The color image forming method of the present invention can be widely applied to other than the apparatus by the color image forming method using an electrostatic latent image, such as a printer, a copying machine and a facsimile.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus using a color image forming method of the present invention.

FIG. 2 shows an apparatus using the color image forming method of the present invention,
FIG. 3 is an enlarged schematic view of an apparatus used as a fixing unit.

FIG. 3 shows an apparatus using the color image forming method of the present invention,
FIG. 3 is an enlarged schematic view of an apparatus used as a fixing unit.

[Explanation of symbols]

 1 Charging Means 2 Image Signal Exposure Means 3 Developing Means 4 Color Signal Exposure Means 5 Transfer Means 6 Thermal Developing Means 7 Fixing Means 8 Cleaning Means 9 Latent Image Carriers 10 Electrostatic Latent Image Visual Ink Particles 11 Recording Medium 12 Releasing Supplying means 13 Heat roller 14 Pressure roller 15 Releasing solution 16 Cleaning pad

Claims (2)

[Claims] 1. A photosensitive silver halide salt that absorbs light of a specific wavelength to form a color latent image, and a dye precursor that oxidizes itself and develops a color while reducing silver ions by heating. In a color image forming method using ink particles for electrostatic latent image development, following the step of developing a color latent image generated by color exposure to a desired color tone by heating, selected from amines, quinones, and phenols Of at least one silver adsorbent selected from compounds having a skeleton structure of triazole, benzimidazole, mercaptotetrazole, or tetraazaindene, which are colorless before and after oxidation, alkylthioureas, and thionamide A mold release solution in which at least one silver complex chlorinating agent selected from a compound having a functional group is dissolved is electrostatically discharged from the heat pressure supply member. A color image forming method, characterized in that heat and pressure are simultaneously applied while being supplied to the latent image developing ink particles to perform heat fixing on a recording medium. 2. An electrostatic latent image developer comprising a photosensitive silver halide salt which absorbs light of a specific wavelength to form a color latent image and a dye precursor which develops a color while reducing silver ions by heating. In the color image forming method using the image-forming ink particles, subsequent to the step of developing a color latent image generated by color exposure to a desired color tone by heating, an acid anhydride, an aldehyde, an isocyanate, or any functional group of epoxy At least one color-free coupler selected from compounds having ## STR3 ## and at least one silver adsorbent selected from compounds having a skeleton structure of triazole, benzimidazole, mercaptotetrazole or tetraazaindene, alkylthio Dissolution of at least one silver complex chlorinating agent selected from compounds having a functional group of ureas and thionamide A color image forming method, characterized in that heat and pressure are simultaneously applied to a recording medium so as to perform heat fixing while supplying a moldable solution from the heat and pressure supplying member to the electrostatic latent image developing ink particles.