JPH04170549A - Electrophotosensitive material and electrophotographic device and facsimile and electrophotographing method using this material - Google Patents

Abstract

PURPOSE:To obtain reproducibility of high gradation and a picture of high quality even in the case of a high speed printer at a process speed of 150 mm/ sec or more by containing a phthalocyanine pigment in a charge generation layer. CONSTITUTION:A charge generation layer contains a phthalocyanine pigment. Since sufficiently high sensitivity is provided in the case of thus using the phthalocyanine pigment of oxytitanium phthalocyanine or the like as a charge generating material, sufficient photoresponsiveness is obtained even in use at a high process speed of 150mm/sec or more, and further by setting Vd (dark potential of sensitive material) to 700 to 1000V by an absolute value, a contrast potential can be spread to easily obtain gradation repeatability. Even in repeated use and environmental fluctuation, excellent electrophotograhic characteristic of very small potential fluctuation is provided.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, an electrophotographic apparatus equipped with the photoreceptor, and an electrophotographic method using the photoreceptor, and particularly relates to an electrophotographic method using the photoreceptor in a reversal development process. The present invention relates to an electrophotographic photoreceptor capable of producing high-quality hard copies with good gradation reproducibility, an electrophotographic apparatus equipped with the photoreceptor, and an electrophotographic method using the photoreceptor.

[Conventional technology]

In recent years, the demand for electrophotographic printers such as laser beam printers, LED printers, and LCD printers as output devices for computers, word processors, facsimile machines, etc. has been rapidly increasing, and at the same time, organic electrophotographic photoreceptors are being installed in these devices. The number of cases is increasing.

As an organic photoreceptor, a two-layer structure in which a charge generation layer and a charge transport layer are laminated in order is generally used for various reasons such as material selectivity latitude, durability, potential stability, high sensitivity, and high response. Many forms are used.

In electrophotographic printers, digital copying machines, etc., the main method is to read the image signal of the original once and then write the image signal using a laser light source, LED, etc.
Methods for reproducing the gradation of the original density include obtaining gradation by changing the dot density, and changing the bright area potential by changing the amount of laser light to change the development contrast between the development bias and the bright area potential. There is a known method of obtaining gradation by

[Problem that the invention is trying to solve]

In the former case, the gradation reproducibility is low because the size of the dots is constant. In addition, in the latter case, it was necessary to increase the development contrast in order to obtain gradation, but with conventional photoreceptors, the slope of light attenuation becomes gentle when the electric field is low, making it difficult to obtain sufficient development contrast. The problem was that I couldn't get it.

Therefore, the present invention improves the above-mentioned drawbacks, and provides an electrophotographic photoreceptor capable of producing high-quality hard copies with good gradation reproducibility in printers and fax machines using a reversal development process, and an electrophotographic photoreceptor equipped with the photoreceptor. An object of the present invention is to provide an apparatus and an electrophotographic method using the photoreceptor.

[Means to solve the problem]

That is, the present invention provides an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer laminated in order on a conductive support, wherein the charge generation layer contains a phthalocyanine pigment. an electrophotographic photoreceptor, an electrophotographic apparatus and a facsimile machine equipped with the photoreceptor, and an electrophotography using an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer laminated in this order on a conductive support and having a reversal development process. The method is characterized in that the charge generation layer contains a phthalocyanine pigment, and the dark potential of the photoreceptor in the latent image forming process is in the range of 700 to 100 V in absolute value, and the process speed is 150 min/sec or more. It is an electrophotographic method.

The present invention will be explained in detail below.

In the present invention, the dark potential of the photoreceptor (hereinafter referred to as 4) in the latent image forming process of an electrophotographic apparatus is set to 700 to 1000 V in absolute value.

■4 is generally set in the range of 600 to 700■ as an absolute value. One reason for this is that when v4 is set to 600v or less, it becomes difficult to maintain a contrast potential between v4 and the bright area potential (hereinafter referred to as If V4 was set to a high potential of 700 V or more, the slope of optical attenuation in the low potential region would worsen, so the effect of setting V4 high could not be obtained. This is especially true when the process speed is 150
It becomes even more noticeable when the speed is higher than mm/sec,
Contrast potential cannot be obtained.

However, when a phthalocyanine pigment such as oxytitanium phthalocyanine is used as a charge-generating material, the process speed is 15% because it has sufficiently high sensitivity.
Sufficient photoresponsiveness can be obtained even when used at high speeds of 0 mlsec or more, and the absolute value of v4 is 700 to 1000.
By setting it to V, the contrast potential can be expanded and gradation reproducibility can be easily obtained. Furthermore, it has excellent electrophotographic properties with extremely small potential fluctuations even after repeated use or environmental changes. Therefore, the effects of the present invention can be fully obtained without any adverse effects.

Next, specific aspects of the electrophotographic photoreceptor will be explained.

As the support having a conductive layer, the support itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indilum, gold, platinum, etc. In addition, plastics with a layer formed by vacuum evaporation of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc., supports and conductive materials made of plastic or paper impregnated with conductive particles For example, a plastic having a polymer with a chemical nature can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The subbing layer is casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
It can be formed from acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is suitably 0.1 micron to 10 micron, preferably 0.1 micron to 3 micron.

Further, it is preferable to provide a conductive layer between the support and the undercoat layer for the purpose of covering unevenness and defects on the support and preventing interference fringes due to scattering when the image input is a laser beam. This can be formed by dispersing conductive powder such as carbon black, metal particles, metal oxide, etc. in a binder resin. The thickness of the conductive layer is preferably 5 to 40 microns, more preferably 10 to 30 microns.

Next, the phthalocyanine pigment used in the charge generation layer will be explained using oxytitanium phthalocyanine as an example. Oxytitanium phthalocyanine is a compound represented by the following general formula.

(In the formula, x, , x, , x3, x are each independently C
! or Br, where n, m, l, k are each independently 0
Represents the number ~4. ) Documents related to synthesis methods and electrophotographic properties include, for example, JP-A-57-148745, JP-A-59-36254, and JP-A-59.
-44054, 59-31965, 61-2392
48, 62-67094, etc. Oxytitanium phthalocyanine obtained according to these methods is used as a charge generating material.

The charge generation layer can be formed by vapor deposition, phenolic resin, urea resin, melamine resin, epoxy resin, silicone resin, vinyl chloride-vinyl acetate copolymer, butyral resin, xylene resin, urethane resin, acrylic resin. This is carried out by dispersing oxytitanium phthalocyanine in a binder resin solution such as polycarbonate resin, polyacrylate resin, saturated polyester resin, phenoxy resin, etc., and applying the solution. The film thickness is preferably 0.05 to 10
μm, more preferably 0.1 to 3 μl.

As the charge transport material, common materials such as pyrazoline compounds, hydrazone compounds, stilbene compounds, triphenylamine compounds, benzidine compounds, and oxazole compounds can be used. A charge transport layer is formed by dissolving these in a solvent together with a binder resin similar to that used for the charge generation layer and applying the solution. The ratio of charge transport material to binder resin is preferably 1:3 to 3:1,
More preferably, the ratio is set to 1:2 to 2:1.

When the ratio of the charge transport material is less than 1:3, the charge transport ability decreases, causing a decrease in sensitivity and an increase in residual potential. On the other hand, if the amount of the charge transport material exceeds 3=1, it is not preferable because the mechanical strength of the charge transport layer decreases and the photoreceptor cannot withstand repeated use.

For forming each layer by these coatings, known coating methods such as a dipping method, a spray method, a beam method, a blade coat, a spinner coat, etc. can be used.

Next, a latent image forming process in an electrophotographic apparatus will be explained. The process of uniformly charging the photoreceptor is usually performed by corona discharge or a direct charging method in which a conductive member is brought into contact with the photoreceptor. In the present invention, the charging process includes
6 is 700-1000 V, preferably 850-100
It is set to 0V. In addition, the portion written by the laser light source as an image signal corresponding to the density of the original is Vl. Fig. 1 shows an example of the schematic configuration of a general transfer type electrophotographic apparatus using the electrophotographic photoreceptor of the present invention. Indicated.

In the figure, reference numeral 1 denotes a drum-type photoreceptor of the present invention as an image carrier, which is rotated at a predetermined circumferential speed in the direction of the arrow around an axis 1a. The photoreceptor 1 is charged by charging means 2 during its rotation process.
The peripheral surface is uniformly charged with a predetermined positive or negative potential, and then exposed to a light image by an image exposure means (not shown) in the exposure section 3 (slit exposure, laser beam scanning exposure, etc.)
receive. As a result, electrostatic latent images corresponding to the exposed images are sequentially formed on the circumferential surface of the photoreceptor.

The electrostatic latent image is then developed with toner by a developing means 4, and the toner developed image is transferred from a paper feed section (not shown) by a transfer means 5 between the photoreceptor l and the transfer means 5 in synchronization with the 10 rotations of the photoreceptor. The images are sequentially transferred onto the surface of the transferred transfer material P.

The transfer material P that has undergone the image transfer is separated from the photoreceptor surface and introduced into the image fixing means 8, where the image is fixed and a copy is produced.
will be printed out on the outside of the aircraft.

After the image has been transferred, the surface of the photoreceptor 1 is cleaned by a cleaning means 6 to remove residual toner, and is further subjected to a charge removal process by a pre-exposure means 7, and is used repeatedly for image formation.

As the uniform charging means 2 for the photoreceptor 1, a corona charging device is generally widely used. Further, for the transfer device 5, corona transfer means is generally widely used.

An electrophotographic apparatus is constructed by combining a plurality of components such as the above-mentioned photoreceptor, developing means, and cleaning means into an apparatus unit, and this unit is configured to be detachable from the apparatus main body. It's okay. For example, the photoreceptor 1 and the cleaning means 6 may be integrated into one device unit, and configured to be detachable using a guide means such as a rail of the device body. At this time, the above-mentioned device unit may include a charging means and/or a developing means.

When an electrophotographic device is used as a copying machine or a printer, light image exposure is performed by converting reflected light or transmitted light from a document, or reading the document into a signal, and using this signal to scan a laser beam, LED, This is performed by driving an array or driving a liquid crystal shutter array.

When used as a facsimile printer, the optical image exposure is exposure for printing received data. FIG. 2 is a block diagram showing an example of this case.

The controller 11 controls the image reading section 10 and the printer 19. The entire controller 11 is controlled by the CPU 17.Read data from the image reading section 1° is transmitted to the other station through the transmission circuit 13. The data received from the other station is sent to the printer 19 through the receiving circuit 12.
sent to.

Predetermined image data is stored in the image memory 16. A printer controller 18 controls a printer 19. Worker 4 is a telephone.

Image information received from the line 15 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 12, decoded by the CPU 7, and sequentially stored in the image memory 16. Ru. and at least 1
When the image information of the page is stored in the memory 16, the image of the page is recorded. CPL 117 is memory 16
One page of image information is read out from the printer controller 18, and the decoded one page of image information is sent to the printer controller 18. When the printer controller 18 receives one page of image information from the CPU 17, it controls the printer 19 to record the image information of that page.

Note that the CPU 17 is receiving the next page while the printer 19 is recording.

Images are received and recorded in the manner described above.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines but also in a wide range of electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.

〔Example〕

Next, the present invention will be explained by examples.

Synthesis of oxytitanium phthalocyanine: A mixture of 50 g of phthalodinitrile, 22.5 g of titanium tetrachloride, and 630 mA of α-chloronaphthalene was heated at 240 to 25 mA in a N2 stream.
The reaction was carried out by heating and stirring at 0°C for 4 hours. The product was filtered, and the resulting mixture of dichlorotitanium phthalocyanine and concentrated aqueous ammonia 380II11 was heated under reflux for 1 hour.

The product was washed with acetone using a Soxhlet, and 22 g
of oxytitanium phthalomucyanine was obtained.

Real JJ Tsuji 1 φ80×! The support was a 360II1m Affi cylinder. A conductive layer composed of the following materials was coated on the support by a dipping method, and heat-cured at 140'C for 130 minutes.
An 8 μm anti-scattering conductive layer was formed.

Next, polyamide resin (product name: Amilan CM-800
0, manufactured by Toshi) by dipping method.
A 1 μ-subbing layer was formed.

Next, 10 parts of oxytitanium phthalocyanine synthesized in the above synthesis example, 4 parts of polyvinyl butyral resin (trade name: S-LEC BX-1, manufactured by Block Chemical Co., Ltd.), and 200 parts of cyclohexanone were mixed using 1φ glass beads. The mixture was dispersed in a sand mill for 10 hours, 300 to 450 (appropriate) parts of tetrahydrofuran was added thereto, and the mixture was coated on the undercoat layer by a dipping method to form a charge generation layer of 0.15 μm.

Next, as a charge transport layer, 10 parts of a stilbene compound having the following structural formula and a bisphenol Z type polycarbonate resin (
(manufactured by Mitsubishi Gas Chemical) was dissolved in 45 parts of monochlorobenzene and 15 parts of dichloromethane to prepare a coating liquid.

This was applied onto the charge generation layer by a dipping method to form a charge transport layer of 26 μm.

The photoreceptor thus created was attached to a laser copying machine (CLC-1, manufactured by Canon) equipped with a semiconductor laser light source, and
Process speed 160mm/sec, V.

The charging conditions were set so that the voltage was -900V.

Further, toner development was carried out using a jumping method using a one-component negative toner, and a developing bias was set at 1,750 square meters.

The results of evaluating the printed images under these conditions are shown in the table.

1 unit ±1 The charge generation layer was coated in the same manner as in Example 1, and as a charge transport layer, 9 parts of a compound having the following structure and a styrene-acrylic copolymer resin (trade name: MS-600, manufactured by Nippon Steel Chemical Co., Ltd.) were added.
10 parts, 40 parts of monochlorobenzene, 1 part of dichloromethane
A coating solution was prepared by dissolving 2 parts. This was applied onto the charge generation layer by a dipping method to form a charge transport layer with a thickness of 25 μm.

V4=-850V using the same laser copying machine as in Example 1
Image evaluation was performed at a developing bias of -700. The results are shown in the table.

Image evaluation was carried out using the same photoreceptor as in Example 1, except that the Hokukai Kaido laser copying machine was used, the stage setting was 600 V, and the developing bias was 450 ■. The results are shown in the table.

As a result, in Examples 1 and 2, good gradation reproducibility in 10 levels was obtained for the 10-level original density pattern. On the other hand, in Comparative Example 1, (1) was set as low as -600V, so a sufficient contrast potential could not be obtained, and only six gradation reproducibility could be obtained.

Contrary ■Process speed of main laser copying machine is 320m/sec
Image evaluation was carried out in the same manner as in Example 1 using the photoreceptor of Example 1, with the 4 setting set to -8000 and the developing bias set to -650. The results are shown in the table.

1 comparison 5 I The photoreceptor was coated in the same manner as in Example 1 up to the undercoat layer.

As a charge generation layer, 10 parts 1 of the following compound, 4 parts polyvinyl butyral resin (trade name: ESLETSUKU BL-3, manufactured by Tsukiki Kagaku), and 200 parts cyclohexanone were dispersed for 50 hours in a sand mill device using 1φ glass beads. 300 to 450 (appropriate) parts of tetrahydrofuran were added to this and applied to the undercoat layer to form a charge generation layer of 0.15 μm.

The charge transport layer was provided under the same conditions as in Example 1.

Image evaluation was performed using the same surface potential settings as in Example 3.

In Example 3, up to 8 gradations out of 10 levels can be reproduced, and the effects of the present invention are fully recognized. On the other hand, in Comparative Example 2, vl was high because the photoresponsiveness of the photoreceptor was slow;
Since a sufficient contrast potential cannot be obtained, gradation reproducibility has deteriorated.

Table (image evaluation) 9.10 gradation reproduction with 10-level density pattern of original ◎ 7.8 gradation reproduction 0 4-6 gradation reproduction △ 3 gradation reproduction or less X [Effects of the invention] As described above, the present invention Electrophotographic photoreceptors and electrophotographic devices have a process speed of 1 in the reversal development process.
Even with a high-speed printer of 50 wn/sec or higher, high gradation reproducibility can be obtained and high-quality images can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a general transfer type electrophotographic apparatus. FIG. 2 is a block diagram of a facsimile machine using an electrophotographic device as a printer. 1: Photoreceptor, 2: Charging means, 3: Exposure section, 4: Developing means, 5: Transfer means, 6: Cleaning means, 7: Pre-exposure means, 8: Image fixing means. Agent Patent Attorney Johei Yamashita

Claims (6)

[Claims] (1) An electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer laminated in order on a conductive support, wherein the charge generation layer contains a phthalocyanine pigment. (2) The electrophotographic photoreceptor according to claim (1), wherein the phthalocyanine pigment is oxytitanium phthalocyanine. (3) An electrophotographic apparatus comprising the electrophotographic photoreceptor according to claim (1) or (2). (4) A facsimile machine comprising the electrophotographic photoreceptor according to claim (1) or (2) and receiving means for receiving image information from a remote terminal. (5) An electrophotographic method using an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer laminated in order on a conductive support and having a reversal development process, wherein the charge generation layer contains a phthalocyanine pigment. and the dark potential of the photoreceptor in the latent image forming process is 700 to 10 in absolute value.
Process speed is 150mm/sec in the range of 00V
An electrophotographic method characterized by the above. (6) The electrophotographic method according to claim (5), wherein the phthalocyanine pigment is oxytitanium phthalocyanine.