JPH03175454A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the occurrence of interference fringes and image defects such as scratches, blur or thin fog density by interposing a transparent intermediate layer contg. dispersed resin powder and/or resin granules between the substrate and the photosensitive layer of a sensitive body. CONSTITUTION:When an electrophotographic sensitive body 3 is irradiated with monochromatic light from the substrate 10 side in an electrophotographic device, a transparent interference preventing layer 11 contg. dispersed resin powder and/or resin granules is interposed between the electrically conductive transparent substrate 10 and the photosensitive layer 12 of the sensitive body 3. Even when the photosensitive layer 12 is electrified and irradiated with monochromatic light from the substrate 10 side, the interference preventing layer 11 irregularly reflects and scatters the monochromatic light. The occurrence of interference fringes is practically prevented and a high-grade image nearly free from image defects can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor that hardly produces interference fringes with respect to monochromatic light.

[Prior Art] It is well known that in electrophotography, a photoreceptor is charged and exposed to light to form an electrostatic latent image, and a developer is applied to the image to make it visible. This method is widely known as a plain paper copying machine.

Electrophotographic methods include electrofax method, Xerox method, and NP method (for example, Japanese Patent Publication No. 42-23910
(described in the publication) etc. are known.

The electrofax method and the Xerox method form an electrostatic image by the so-called Carlson process, which uses a photosensitive plate on which a photoconductor layer such as zinc oxide, OPc, amorphous selenium, or α-3L is formed on a support. The photoconductor surface was negatively charged by corona discharge, then the original image was irradiated to attenuate the charge in the irradiated area, and the electrostatic image that followed the light and dark pattern of the original image was developed and visualized with charged colored particles. The image is then fixed or transferred onto another support such as paper and then fixed to obtain an electrophotographic image.

The NP method uses the capacitance difference and photoconductivity between the photoconductor layer and the insulating layer used above to form an electrostatic image, and then similarly develops, transfers, and fixes the image to form an electrophotographic image. It is something that gives you an image.

Copying devices utilizing these electrophotographic methods have been developed to date.

A typical electrophotographic device has a copying process in which a latent image is formed by charging, exposing, etc. from the photosensitive layer side (outside) of a cylindrical photoreceptor or a loop-shaped endless photoreceptor. In order to downsize the apparatus and simplify the process, an apparatus has been devised in which exposure is performed from the photoreceptor support side (inside) of the photoreceptor. Examples of exposure from the photoreceptor support side include image exposure, pre-transfer exposure, pre-cleaning exposure, and static elimination exposure.

For uniform exposure of the photoreceptor, such as pre-transfer exposure, pre-cleaning exposure, or static elimination exposure, use a fluorescent lamp as a light source inside the photoreceptor.
A halogen lamp or tungsten lamp is installed, and light is applied only to the necessary areas through a slit or the like. It is also possible to use a light source such as a laser beam or an LED array where necessary.

In contrast to these exposures, in the case of so-called analog copying machines that use the reflected light from the copied original for image exposure, it becomes complicated and bulky to enter the image exposure from the support side of the photoreceptor. There is no benefit as it will lead to On the other hand, when image exposure is carried out from the support side, the image is necessarily exposed using so-called digital light such as laser light, LED array, etc. that has been subjected to electrical processing of the image.

[Problems to be Solved by the Invention] However, when performing exposure with so-called digital light such as laser light or an LED array, the laser light and L
Since ED light is monochromatic light, light interference occurs within the electrophotographic photoreceptor and at the interface of the support, resulting in potential unevenness on the electrophotographic photoreceptor. This potential unevenness is particularly problematic during image exposure, causing image defects called so-called interference fringes.

The present invention has been made in view of the above-mentioned problems, and its purpose is to eliminate almost all image defects in an electrophotographic apparatus having a process of irradiating monochromatic light from the light-transmitting conductive support side of an electrophotographic photoreceptor. An object of the present invention is to provide an electrophotographic photoreceptor that can create high-quality images that do not occur.

[Means for Solving the Problems] The present invention having the above-mentioned object provides an electrophotographic apparatus having a process of irradiating monochromatic light from the light-transmitting conductive support side of an electrophotographic photoreceptor, in which the support and the photosensitive layer of the photoreceptor are Image formation is performed using an electrophotographic photoreceptor having a light-transmissive interference canceling layer in which fine particles selected from resin powder and particles are dispersed between the photoreceptor and the photoreceptor.

Here, the material forming the intermediate layer is not limited to resin, but preferably a material that is transparent and has a large refractive index. Its Mohs hardness is lower (softer) than both the Mohs hardness of the support and the photosensitive layer.
This is very important.

Furthermore, the shape of the microscopic bodies forming the intermediate layer is not limited to powder or particles, but also includes fibrous and flake shapes.

[Function] In a copying machine equipped with the photoreceptor of the present invention, even when a charged photosensitive layer is irradiated with monochromatic light from its support side, microscopic particles dispersed between the photosensitive layer and the support are removed. As a result of the interference canceling layer consisting of diffusely reflecting and scattering monochromatic light, interference fringes are substantially not generated.

[Embodiment] Hereinafter, the present invention will be explained based on preferred embodiments.

The material of the support for the photosensitive layer used in the present invention can be selected from light-transmissive glass, resin, and the like. Preferred examples of the resin include PET (polyethylene terephthalate), PVDF (polyvinylidene fluoride), polyarylate, polysulfone, polyamide, acrylic resin, acrylonitrile resin,
Methacrylic resins, vinyl chloride resins, vinyl acetate resins, phenolic resins, epoxy resins, polyesters, alkyd resins, polycarbonates, polyurethanes, or copolymers containing two or more of the repeating units of these resins, such as styrene-butane. Gen copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, etc. may be mentioned.

The suitable shape of the support may be any of a cylindrical shape, a drum shape, or a looped endless sheet shape.

Next, conductive treatment is performed on the photosensitive layer side of the support.

Examples of the conductive treatment method include metal or conductive material vapor deposition, sputtering, plasma CVD, plating, and the like. Examples of preferred metals or conductive materials include Al, Au,
Cu, Ag, Ni, Ti, Zn, Cr, I
Examples include metals such as n, Sn, Pb, and Fe, and alloys thereof, as well as metal oxides such as ITO, 5no2, and alumite, and those doped with halogen elements such as chlorine and iodine to these metals and metal oxides. be able to.

Another method is to coat the photosensitive layer side of the support with a conductive polymer.

The conductive layer has a surface resistance of 109Ω or less, preferably 10
``The film is formed so that it is less than Ω.

The interference canceling layer provided on the conductive support is made of, for example, fine particles or fine particles of a resin or oligomer such as acrylic resin, styrene-acrylic resin, polystyrene, polyurethane, polyester, fluorinated hydrocarbon resin, polyamide, or polymethylsilsesquioxane. The powder can be formed, for example, by dispersing the powder in a binder resin layer and coating this dispersion onto a light-transmissive, electrically conductive support.

The average particle size of the fine particles or fine powder of the resin or oligomer is usually 10 μm or less, preferably 3 μm or less.

Further, the proportion contained in the binder resin is 10 to 80% by weight, preferably 20 to 60% by weight, based on the formulation.

When the average particle diameter exceeds 10 μm, image defects such as image unevenness are likely to occur. Furthermore, if the proportion of microscopic objects contained in the binder resin is less than 10%, interference fringes will not disappear, resulting in image defects. In addition, if it is 80% or more, it not only reduces the light transmittance of the intermediate layer and causes sensitivity deterioration, but also deteriorates the film formation properties of the interference canceling layer and causes marks, scratches, etc. on the copied image. This results in image defects.

As the resin component used in the interference cancellation layer of the present invention, many existing resin components can be used, but copolymerized nylon, N
-Solvent soluble polyamides such as methoxymethylated nylons, phenolic resins, polyurethanes, polyureas or polyesters are suitable.

In the present invention, the photosensitive layer may be of a laminated structure type in which a charge generation layer and a charge transport layer are functionally separated, or a single layer type having both functions.

In the case of a photoreceptor with an N-layer structure, the charge generation layer contains a charge generation substance such as an azo pigment such as Sudan red or guiampurus, a quinone pigment such as pyrenequinone or anthrone, a quinocyanine pigment, a perylene pigment, or an indigo pigment such as indigo or thioindigo. Pigments, azulenium salt pigments, phthalocyanine pigments such as copper phthalocyanine, etc. are dispersed in binder resins such as polyvinyl butyral, polystyrene, polyvinyl acetate, acrylic resins, polyvinyl pyrrolidone, ethyl cellulose, cellulose acetate butyrate, etc., and this dispersion is prepared. It can be formed by coating on the above-mentioned intermediate layer. The thickness of such a charge generation layer is usually set to 5 μm or less, preferably 0.05 to 2 μm.

The charge transport layer provided on the charge generation layer is a polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene, or phenanthrene in the main chain or side chain, or a nitrogen-containing heterocycle such as indole, carbazole, oxadiazole, or pyrazoline. If necessary, it can be formed using a coating liquid in which a charge transporting substance such as a compound of the formula formula, a hydrazone compound, a styryl compound, etc. is dissolved in a resin having film-forming properties.

Examples of resins with such film-forming properties include polyester,
Examples include polycarbonate, polymethacrylate, polystyrene, and the like.

The thickness of the charge transport layer is usually 5 to 40 μm, preferably 10 μm.
Set to ~30 μm.

Further, the laminated structure type photoreceptor may have a structure in which a charge generation layer is laminated on a charge transport layer in the reverse order of the above order.

Furthermore, in the case of a single-layer type photoreceptor, it can be formed by incorporating a charge generating substance and a charge transporting substance as described above into the resin.

Further, in the present invention, an organic photoconductive polymer layer such as polyvinylcarbazole or polyvinylanthracene, a selenium vapor deposition layer, a selenium-tellurium vapor deposition layer, an amorphous silicon layer, etc. can also be used as the photosensitive layer.

Examples actually carried out will be described below as Examples [1 to 10], but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Examples 1 to 5 and Comparative Examples 1 to 4 P with a surface of 1 m, 100 cm x 25 cm, and a thickness of 1100 u.
A1 was vapor-deposited on one side of the ET sheet to create a light-transmissive and electrically conductive support.

Next, copolymerized nylon resin (average molecular i 14000)
A paint stock solution for an interference canceling layer was prepared by dissolving 2 parts and 6 parts of N-methoxymethylated 6-nylon resin (average molecular fm 11000) in 92 parts of methanol.

Polymethylsilsesquioxane with an average particle size of 21 Lm is added to the resin content of this paint stock solution by 1% on a formulation basis.
They were added and dispersed to a content of 0.20.50.60 or 80% by weight to obtain paints for erasing dryness of Examples 1 to 5, respectively.

In addition, polymethylsilsesquioxane was added at 5.85% each.
Alternatively, they were added and dispersed to a content of 90% by weight, and used as paints for Comparative Examples 2 to 4, respectively.

The intermediate layer paint stock solution with no additives was used as the paint of Comparative Example 1.

The interference-cancelling layer coatings prepared in this way were dip-coated onto the conductive layer and dried at 100° C. for 40 minutes to form an interference-cancelling layer with a thickness of 3.0 μm.

Next, 3 parts of a disazo pigment having the following structural formula, 2 parts of polyvinylbenzal (benzal conversion rate: 80%, average molecular weight: 11,000), and 35 parts of cyclohexanone were mixed and dispersed for 12 hours using a sand mill device using glass beads with a diameter of 1 mm. A dispersion liquid for a charge generation layer was prepared by adding 60 parts of methyl ethyl ketone (MEK). This dispersion was dip coated onto each of the interference canceling layers mentioned above and dried at 80°C for 20 minutes to form a film with a thickness of 0.2 μm.
A charge generation layer of m was formed.

Next, 10 parts of a styryl compound of the following structural formula and 10 parts of polycarbonate (average molecular weight ff1460001) were dissolved in a mixed solvent consisting of 40 parts of dichloromethane and 20 parts of monochlorobenzene, and this solution was dip-coated onto the above charge generation layer. , and was dried at 120° C. for 60 minutes to form a charge generation transport layer having a thickness of 25 μm.

The thus produced photoreceptor was joined at both ends so that the photosensitive layer was on the outside to form a loop-shaped endless sheet, which was then mounted on an electrophotographic apparatus shown in FIG. The electrophotographic apparatus shown in Fig. 1 charges a photoreceptor with a -6kV corona discharge, then emits one beam of light from a semiconductor laser with a wavelength of 780 nm from the support side, and then performs toner development, transfer, cleaning, and charge removal from the support side. It performs exposure.

Development was carried out by so-called reversal development using negative toner.

Using this device, 5mm square alphabet, solid black,
Perform halftone and solid white images, and 10
A continuous durability test of 00 sheets was conducted on these photoreceptors.

As a result, when the photoreceptors of Examples 1 to 5 were used, good initial images were obtained for alphabetical, solid black, halftone, and solid white images. Furthermore, 100 consecutive
Good images could be stably obtained even in the additional durability image formation of 0 sheets.

On the other hand, in the photoreceptors of Comparative Examples 1 and 2 in which the intermediate layer did not contain polymethylsilsesquioxane or added 5% polymethylsilsesquioxane, interference fringes appeared from the initial image stage, resulting in image defects.

In addition, in the photoreceptors of Comparative Examples 3 and 4 using intermediate layers containing 85 or 90% of polymethylsilsesquioxane,
Image defects such as alphabetical image blur, halftone image unevenness, and low image density occurred from the initial image stage.

Examples 6 to 10 and Comparative Examples 5 to 7 In place of the interference canceling layer paint of Example 1, 1 part of hexamethylene diisocyanate, 13 parts of poly(oxypropylene) glycol (hydroxyl value 25 mg KOH/g), and copoly( An intermediate layer paint stock solution was prepared by dissolving 6 parts of oxypropylene)(oxyethylene)triol (hydroxyl value: 51 mg KOH/g) and 0.001 part of dibutyltin dilaurate in 80 parts of MEK. Examples 6 to 10 were added and dispersed to the solid content of this paint stock solution on an acrylic resin with an average particle size of 3 μm to a content of 10, 20, 50, 60 or 80% by weight, respectively.
It was used as a paint for the interference canceling layer.

Further, the additives were added and dispersed on an acrylic resin to a content of 5 or 90% by weight, respectively, and were prepared as paints for Comparative Examples 6 and 7, respectively.

Furthermore, a stock solution of a paint for an intermediate layer on the acrylic resin was prepared, and this was designated as Comparative Example 5.

The coating for the interference canceling layer or the intermediate layer prepared in this manner was applied by dip coating onto the above conductive layer, and then heated at 140'C for 60 minutes.
It was dried and cured for 0 minutes to form a polyurethane interference canceling layer or intermediate layer having a film thickness of 1.5 parts m.

Next, a charge generation layer and a charge transport layer were formed on each interference canceling layer or intermediate layer in the same manner as in Example 1 to produce an electrophotographic photoreceptor. The electrophotographic photoreceptor thus manufactured was mounted in the electrophotographic apparatus shown in FIG. 1 in the same manner as in Example 1, and the same tests as in Example 1 were conducted.

As a result, with the photoreceptors of Examples 6 to 10, good initial images were obtained for alphabetical, solid black, halftone, and solid white images. Furthermore, good images could be stably obtained even during continuous additional durability image production of 1000 sheets.

On the other hand, in the photoreceptors of Comparative Examples 5 and 6, in which an intermediate layer with no addition or 5% addition was used on the acrylic resin, interference fringes appeared from the initial image stage, resulting in image defects.

In addition, in the photoreceptor of Comparative Example 7 using an intermediate layer containing 90% of the acrylic resin, image defects such as alphabetical image blur, halftone image unevenness, and low image density occurred from the initial image stage.

[Effects of the Invention] The electrophotographic photoreceptor of the present invention has a light transmitting property in which resin powder and/or resin particles having an average particle size of 5 μm or less, preferably 3 μm or less are dispersed between the support of the photoreceptor and the photosensitive layer. By providing an intermediate layer, interference fringes, image scratches, and
It shows the effect of substantially eliminating image defects such as image blur or fog and low density.

Further, by using the photoreceptor of the present invention, copying machines, printers, etc. can be made smaller and lighter, and high-quality images can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an electrophotographic apparatus, showing an example in which a laser is used as an image exposure light source. FIG. 2 is a partial sectional view of the photoreceptor taken along line A-A. 1... Charger 2... Transfer charger 3... Photoreceptor 4... Developing device 5... Cleaner 6... Static elimination lamp 7... Laser light source 8... Polygon mirror 9. ... Reflection plate 10 ... Light-transmitting conductive support 11 ... Interference canceling layer 12 ... Photosensitive layer.

Claims (4)

[Claims] (1) In an electrophotographic photoreceptor using an electrophotographic process in which monochromatic light is irradiated from the light-transmitting conductive support side of the electrophotographic photoreceptor, fine particles are dispersed between the conductive support and the photosensitive layer. An electrophotographic photoreceptor comprising a light-transmitting interference canceling layer. (2) The electrophotographic photoreceptor according to claim 1, wherein the fine particles dispersed in the interference canceling layer are resin, and the weight ratio thereof is 0.1 part or more and 0.8 parts or less. (3) The electrophotographic photoreceptor according to claim 1, wherein an electrophotographic process is used in which the monochromatic light to be irradiated is laser light. (4) The electrophotographic photoreceptor according to claim 1, wherein an electrophotographic process is used in which the monochromatic light to be irradiated is LED light.