JPH02115865A - Image forming method - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an image forming method for recording and preserving an electrostatic latent image that is wet-developed in an electrophotographic process or the like.

[Summary of the invention]

The present invention provides an image forming method in which an electrostatic latent image is formed on a film laminated on a photoreceptor, developed, and then the film is peeled off from the photoreceptor. , which aims to faithfully reproduce electrostatic latent images to form high-quality images at high speed, and to form images with high transfer efficiency at low cost.

[Prior Art] In the field of image forming technology, a method in which light is selectively irradiated onto a negatively charged photoreceptor according to an image signal and the formed electrostatic latent image is developed is generally an electrostatic method. It is called an electrophotographic process. This electrostatic electrophotographic process can be roughly divided into dry development method and wet development method.

Among these, the wet development method uses a liquid developer in which a dye or pigment as a coloring agent is dispersed in the form of fine particles in an insulating medium. According to the wet development method, it is possible to obtain gradation and resolution comparable to silver halide photography, and the weather resistance of the formed image is excellent, especially when pigments are used as colorants. , development is progressing in various fields.

[Problem to be solved by the invention]

By the way, in order to record and preserve the electrostatic latent image developed as described above in a form that can be immediately visually recognized,
It is preferable to transfer this onto a suitable transfer target. However, in the conventional wet development method, the adsorption between the colorant particles and the photoreceptor is too strong, resulting in a decrease in transfer efficiency, and the method is not necessarily suitable for the purpose of image formation in pursuit of high image quality.

On the other hand, image forming methods that do not involve transfer, such as so-called electro-fafx, have also been proposed. This is a method of directly forming an image on a transparent photoreceptor such as polyvinyl carbazole or a white photoreceptor such as ZnO. However, since the amount of aggravating dye used is naturally limited due to the need to maintain appropriate transparency or whiteness of the photoreceptor, it is difficult to improve sensitivity and there is a limit to speeding up image formation and readout. Furthermore, there are disadvantages such as the low dispersion stability of the colorant and the inability to reuse the photoreceptor due to no transfer, resulting in high costs. It is only used for limited purposes such as.

Therefore, the present invention has been proposed in view of the conventional situation, and is capable of forming high-quality images at high speed.
Moreover, it is an object of the present invention to provide an image forming method that is low cost and has extremely high transfer efficiency.

[Means to solve the problem]

In order to achieve the above-mentioned object, the image forming method of the present invention includes laminating a film that transmits at least light from an exposure light source on a photoreceptor, and forming and developing an electrostatic latent image on the film. Thereafter, in an image forming method in which the film is peeled off from the photoreceptor, a film having a contact angle with methylene iodide of 60 degrees or less is used.

The image forming method of the present invention is based on the premise that an electrostatic latent image is first formed and developed on a film laminated on a photoreceptor. First, the principles of formation and development of this electrostatic latent image will be explained with reference to FIG. For convenience, FIG.
It is shown that each process is applied sequentially to the process.

First, in a charging step, the surface of the film (8) laminated on the photoreceptor (1) is uniformly charged, for example, negatively, using a suitable charging means such as a corona discharger (2).

In the next exposure step, selective light irradiation corresponding to image information is performed using an appropriate exposure means such as semiconductor infrared laser light m (3). As a result, the negative charge disappears only in the exposed area.

Here, as the photoreceptor (1), a well-known organic photoconductor or an inorganic photoconductor can be used; for example, the organic photoconductor can be selected from a wide range of well-known materials, The one that has been put into practical use is poly-
Electrophotographic photosensitive substrate, poly-
N-vinylcarbazole sensitized with biryllium base dyes, poly-N-vinylcarbazole sensitized with cyanine dyes, electrophotographic photosensitive substrates whose main components are organic pigments such as phthalocyanine, dyes and resins, etc. An example is an electrophotographic photosensitive substrate mainly composed of a eutectic complex consisting of: On the other hand, examples of inorganic photoconductors include zinc oxide, zinc sulfide, cadmium sulfide, selenium, selenium-tellurium alloy, selenium-arsenic alloy, selenium-tellurium-arsenic alloy, amorphous silicon-based materials, etc. These may be dispersed in a suitable resin such as silicone resin, acrylic resin, or alkyd resin.

On the other hand, a film (8) laminated on the photoreceptor (1)
As such, it must be able to transmit light from the exposure light source. Therefore, it does not necessarily have to be colorless when special effects or decorative uses are envisaged. Furthermore, in the present invention, since an image is formed directly on the film, it is necessary that the film is well wetted by the developer.

In order to meet such requirements, the contact angle with respect to methylene iodide is required to be 60 degrees or less. The contact angle for methylene iodide is as shown in Figure 2.
When methylene iodide (10) is attached onto the film (9), the methylene iodide (10) and the film (
The contact angle θ is 60 degrees or more, which is the angle θ formed with the surface of the film (9) when a tangent is drawn from the contact end of the film (9) in the tangential direction of the methylene iodide (10), It has poor wettability with the developer, making it impossible to obtain high-quality images. Therefore, materials that satisfy these conditions include, for example, polyethylene 5 polyvinylidene chloride-polyvinyl chloride copolymer, polyvinyl chloride (PVC),
Polyimide, polyamide, polypropylene, etc. can be used. Further, the film used here needs to have a contact angle with respect to methylene iodide of 60 degrees or less at least at the operating temperature. Further, the film may be an insulating film or a conductive film. When the film is an insulating film, it is necessary to use a film that has a longer dark decay time than the photoreceptor.

On the other hand, in the case of a conductive film, it is necessary to use a film having a dark decay time shorter than that of the photoreceptor. Note that the dark decay time mentioned above refers to the time required for the amount of charge to decrease by half when a material charged to a certain charge is left in a dark place.

In the next developing step, the laminate of the film (8) on which the electrostatic latent image has been formed as described above and the photoreceptor (1) passes over the developing tank (4). The developer tank (4) contains a developer (7) in which positively charged colorant particles (6) are dispersed in an insulating dispersion medium (5). (6) migrates toward a negatively charged site on the film (8) and attaches thereto.

Here, as the above-mentioned insulating dispersion medium (5), various conventionally known liquids can be used, but due to the necessity of not damaging the electrostatic latent image during the development operation, a liquid with an electrical resistance of 109Ω is used.
- It is preferable to select a non-aqueous solvent with a dielectric constant of 3 cm or more and a dielectric constant of 3 or less. For example, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, polysiloxanes, etc. can be used, but -C is volatile, safe, and toxic.

Isoparaffinic petroleum solvents are preferred from the viewpoint of odor and the like. Examples of commercially available isoparaffinic petroleum solvents include Isopar G, Isopar H Isopar L, Isopar manufactured by Konso Corporation, and Shell Dull 71 manufactured by Shell Oil Company.

Furthermore, as the colorant particles (6) to be dispersed in the insulating dispersion medium (5), conventionally known inorganic pigments, organic pigments, dyes, and mixtures thereof can be used.

Examples of inorganic pigments include chromium pigments, cadmium pigments, iron pigments, cobalt pigments, ultramarine blue, and navy blue. In addition, organic pigments and dyes include Hansa Yellow (C, 1, 11680), Benzine Yellow G (
C,1,21090), benzidine orange (C,1
゜21110), Fast Red (C, 1,3708
5) , brilliant carmine 3 B (C,1,16
015-Lake), Phthalocyanine Blue (C, 1,
74160), Victoria Blue (C.

1.42595-Lake), Spirit Black (
C, 1,50415), oil blue (C, 1,743
50), Alkaline Blue (C11, 42770A),
Fast Scarlet (C, [12315), Rhodamine 6 B (C, 145160), Rhodamine Lake (C, 1, 45160-Lake), Fast Sky Blue (C, 1, 74200-Lake), Nigrosine (C, 1, 50415) ), carbon black, etc. These can be used alone or as a mixture of two or more, and those having the desired color development may be selected and used.

Alternatively, a developer prepared by dispersing a coloring agent in an electrically insulating organic compound that is solid at room temperature may be used by heating it to an appropriate temperature. Examples of the electrically insulating organic compound in this case include paraffins, waxes, and mixtures thereof, as well as polyethylene.

Crystalline polymers having long alkyl groups in side chains, such as polyacrylamide, poly-n-stearyl acrylate, or polyacrylate homopolymers or copolymers, can be used. Moreover, the above-mentioned substances can be used as the colorant particles.

When such an electrostatic latent image developer is used, it can be held on some kind of support and made into a sheet or tape form without putting it in the developing tank (4) as described above, which makes it easier to handle. The quality will further improve.

In any of the developers (7), in addition to the insulating dispersion medium (5) and colorant particles (6), a resin may be used in combination for the purpose of improving the dispersibility and fixing properties of the colorant. As such resin, known materials can be appropriately selected and used, and examples include rubbers such as butadiene rubber, styrene-butadiene rubber, cyclized rubber, and natural rubber, styrene resins, vinyltoluene resins, acrylic resins, Methacrylic resin, polyester resin, polycarbonate resin.

Synthetic resins such as polyvinyl acetate resin, rosin resin,
Examples include hydrogenated rosin resins, alkyd resins containing modified alkyds such as linseed oil-modified alkyd resins, and natural resins such as polyterpenes.

In addition, modified phenolic resins such as phenol-formalin resin, phthalate pentaerydrift, coumaron-indene resins, ester gum resins, vegetable oil polyamide resins, etc. are also useful, and polyvinyl chloride, chlorinated polypropylene, etc. halogenated hydrocarbon polymers, vinyltoluene-butadiene. Synthetic rubbers such as butadiene-isoprene, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, polymers of acrylic monomers with long chain alkyl groups such as lauryl acrylate, octyl acrylate, or other polymerizable polymers. Copolymers with Zimmer (for example, styrene-lauryl methacrylate copolymer, acrylic acid-lauryl methacrylate copolymer, etc.), polyolefins such as polyethylene, polyterpenes, etc. can also be used.

Furthermore, a charge donor is usually added to the developer,
The developer used here is no exception. The charge-donating agents used are, for example, metal salts of fatty acids such as naphthenic acid, octenoic acid, oleic acid, stearic acid, isostearic acid or lauric acid, and sulfosuccinic acid esters. metal salts, oil-soluble sulfonic acid metal salts, phosphate ester metal salts, abietic acid metal salts, aromatic carboxylic acid metal salts,
Aromatic sulfonic acid metal salts, etc.

Moreover, in order to improve the electrical charge of the colorant particles (6), S i Oz+Aj2z03. T i 01. Z'n
O.

GazOs+ Into=, GeOz, 5nOz, P
Metal oxide fine particles such as boxMgO or a mixture thereof may be added as a charge enhancer.

Finally, in the fixing process, the colorant particles (6) adhering to unnecessary areas are removed, and the electrostatic latent image is developed on the film (8) through a static elimination process.

Thereafter, the film (8) is peeled off from the photoreceptor (1). Here, if the film (8) itself has sufficient rigidity and can withstand storage and viewing on its own, it may be used as is. For example, the film (8) may be directly
Examples include use as a sheet for HP (overhead projector). Alternatively, after the film (8) is peeled off, it may be pasted onto another suitable transfer target.

In this case, if the image forming surface of the film (8) and the object to be transferred are attached in contact with each other, the film (8)
acts as a protective film, making it possible to perform so-called laminate coating simultaneously with image transfer.

Here, the material that can be used as the transfer medium may be any material that can be impregnated with the above-mentioned insulating dispersion medium to some extent, such as various papers such as natural paper, synthetic paper, cotton, linen, etc. fabrics or non-woven fabrics made of vegetable fibers and animal fibers such as silk and sheep; organic synthetic fibers such as polyamide, polyester, polyacetal and polyurethane; ceramics;
Cloth or non-woven fabric made of inorganic fibers such as carbon, metal.

Meshes made of organic polymers, polymeric foams such as polyurethane foam, etc. 0 To save in the form of ordinary documents,
From the viewpoint of improving visibility, it is preferable to use white paper or the like as the transfer target, but of course the transfer target is not limited to this.

The image forming method according to the present invention is not limited to forming a monochrome image, but can also be applied to, for example, forming a full-color image using developers of yellow, magenta, and cyan colors. In this case, the light development method may be repeated for each color developer, and the order of development may be selected depending on the type of light source used during exposure. For example, when an infrared laser is used, the order is yellow → magenta → cyan, and when ultraviolet light is used, the order is cyan → magenta → yellow. Furthermore, if necessary, inking may be done with black, and this black development may be performed at an appropriate location of the development of each color.

Since the material used has a contact angle of 60 degrees or less, it is well wetted by the developer.

Therefore, the electrostatic latent image is faithfully reproduced, thereby forming a high quality image.

If the film is removed from the photoreceptor in a state in which the electrostatic latent image has been developed, it becomes possible to record and store the film in a state where it can be immediately visually recognized. Furthermore, if this is applied to an appropriate transfer target, the transfer efficiency will be 100%, and one photoreceptor can be used any number of times.

[Effect]

In the image forming method according to the present invention, a charged charge is applied to the surface of a film laminated on a photoreceptor, and then the film is selectively exposed to light from an exposure light source according to an image signal. An electrostatic latent image is formed. and,
When a developer is attached to the electrostatic latent image, the developer migrates toward the electrical charge of the film, and selective development is performed.

At this time, the above film was applied to methylene iodide [Example] Hereinafter, specific examples to which the present invention is applied will be described.

In this example, an electrostatic latent image is formed using a photoconductor laminated with a polyethylene film, and after the electrostatic latent image is developed with a cyan developer, the polyethylene film is transferred to the photoconductor. This is an example of peeling it off and pasting it on plain paper.

The photoreceptor used in this example was prepared by placing 1 g of polyvinyl carbazole as a photosensitizer on a sheet (50 μm thick) made of modified vinyl acetate resin, and 0.0 g of cyanine dye (manufactured by Nippon Kanko Shiki Co., Ltd., trade name NK2982) as an exacerbating agent. 2 mg
A photosensitive layer N (layer thickness 200 μm) containing the following was formed. On top of this photoreceptor, a film of polyethylene (thickness: 9 μm) having a contact angle of 45 degrees with respect to methylene iodide was adhered and laminated.

Further, the developer used in this example is the aforementioned electrostatic latent image developer previously proposed by the applicant of the present application.

This was prepared as follows. First, the colorant Lionol Blue KX-Fl (manufactured by Toyo Ink Co., Ltd.) 0.6
25 g and isoparaffinic solvent (manufactured by Idemitsu Oil Co., Ltd.,
0.5 g of the product (trade name: rP 2825) was kneaded by the Zuber-Mercy method until it became a paste, and the colorant was made into small particles. Next, this paste was dispersed in another isoparaffin solvent (manufactured by Esso, trade name: Isopar H) 50id, and a dispersion treatment was performed for 12 hours in a paint shaker together with alumina beads. Furthermore, 0.5 g of a 50% toluene solution of acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., trade name FRIOI), 0.025 g of zirconium naphthenate, and 0.0 g of calcium naphthenate, which serve as charge-donating agents.
．． 025 g was added to obtain a concentrated developer. Next, an isoparaffinic solvent with a melting point of 42 to 44°C (manufactured by Esso,
A cyan electrostatic latent image developer was prepared by melting (trade name: Isopar G) 120 d at 70° C. and dispersing the above-mentioned concentrated development 1 iq5 rrrl therein.

To form an image, first, corona discharge was applied to the photoconductor laminated with polyethylene film to negatively charge the entire photoconductor, and then selective exposure was performed using a semiconductor laser to form an electrostatic latent image on the polyethylene film. 0
Next, a suitable heating means (not shown) is provided, for example, in the developing tank so as to keep the developer in a molten state.

) to develop the electrostatic latent image while heating the developer and applying a bias voltage to the developer to prevent unnecessary adhesion of colorant particles due to the residual potential in the exposed area, thereby forming an image on the polyethylene film. Formed.

The above development time was about 3 seconds. Further, the polyethylene film was peeled off from the photoreceptor through a fixing process and a static elimination process, and was attached to plain paper to transfer the image.

This ff1LL In Comparative Example 1, a film having a contact angle of 60 degrees or more with respect to methylene iodide was used as the film to be laminated on the photoreceptor, and an image was formed on the film under the same conditions as in Example 1, The image was transferred to plain paper. For the film having a contact angle of 60 degrees or more with respect to methylene iodide, polyvinylidene fluoride (contact angle 63 degrees) and polytrifluoroethylene (contact angle 71 degrees) were used.

Compared to the image obtained in Example 1, the resolution and one-level gradation were all inferior.

In addition, all of these can be pasted together with the film on plain paper.
Therefore, the transfer efficiency was 100%, and the photoreceptor could be used repeatedly.

In this embodiment, the case where a cyan monochrome image is formed has been explained, but it goes without saying that the present invention can also be applied to the formation of a full color image. The charging process, the exposure process, the developing process, and the neutralizing process are repeated for each of the three primary colors, and finally, the transfer is performed all at once. Even when full-color image formation is performed, the photoreceptor after transfer can be used repeatedly.

The image in Example 1 transferred onto plain paper as described above had high resolution and excellent gradation. On the other hand, the image obtained in Comparative Example 1 using a film with a contact angle of 60 degrees or more with respect to methylene iodide shows the above [Effect of the Invention] As is clear from the above explanation, no matter which film is used, According to the image forming method of the present invention, since a film that is well wetted by the developer is used, it is possible to faithfully reproduce the electrostatic latent image formed on the film, thereby improving gradation and It is possible to form high-quality images with excellent resolution.

Furthermore, since the film covers the surface of the image at the same time as the image is formed, it is possible to protect the image, improve recording stability, and provide special effects characterized by decorativeness such as gloss. Furthermore, since the photoreceptor after transfer can be used repeatedly, it is more economical than conventional methods such as electrofax, which do not involve transfer. Furthermore, since a full-color image can be formed at once without repeating independent transfer processes for each of the three primary colors, high-speed image formation can be achieved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining the principle of a method for developing an electrostatic latent image, which is a pre-stage of image formation. FIG. 2 is an enlarged schematic view of the main part showing the state in which methylene iodide is attached to the surface of the film. 3 ・ ・ 4 ・ ・ 5 ・ ・ 6 ・ ・ 7 ・ ・ 8.9 10 ・ Semiconductor infrared laser light source Development tank Insulating dispersion medium Colorant particles Developer... Film - Methylene iodide

Claims (1)

[Claims] laminating a film that transmits at least light from an exposure light source on the photoreceptor, forming an electrostatic latent image on the film;
An image forming method comprising peeling the film from the photoreceptor after development, the method comprising using a film having a contact angle of 60 degrees or less with respect to methylene iodide.