JP3184708B2 - Electrophotographic photoreceptor, process cartridge having the electrophotographic photoreceptor, and electrophotographic apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member which is charged by a direct charging means and contains a specific resin. The present invention also relates to a process cartridge and an electrophotographic apparatus having the charging unit and the electrophotographic photosensitive member.

[0002]

2. Description of the Related Art When an image is obtained by performing basic processes such as charging, exposure, development, transfer, fixing and cleaning on an electrophotographic photoreceptor, most of the charging processes have conventionally employed a high voltage (DC5 to DC5) on a metal wire. 8 kV) was applied, and charging was performed by the generated corona, which was a so-called corona charging method. However, in this method, a corona product such as ozone or NOx adheres to the surface of the photoreceptor, an image is blurred due to deterioration of the photoconductive layer itself, an image is blurred, or an image is white due to a stain on the wire. And black streaks may occur. In particular, photoconductors in which the photosensitive layer contains an organic photoconductor have lower chemical stability than photoconductors that use inorganic photoconductors such as selenium and amorphous silicon. A reaction (mainly an oxidation reaction) occurs and tends to deteriorate.

In corona charging, only 5% to 30% of the current flowing to the photoreceptor flows, and most of the current flows to the shield plate, and the charging means is inefficient in terms of electric power.

[0004] As a method of solving such a problem,
JP-A-57-178267, JP-A-56-104
351; JP-A-58-40566; JP-A-58-139156; JP-A-58-150975.
A so-called direct charging method of charging a photoconductor by applying a voltage to a charging member in contact with the surface of the photoconductor without using a corona discharger has been proposed in Japanese Patent Application Laid-Open No. H11-163873. Specifically, a charging member such as a conductive elastic roller is brought into contact with the surface of the photoconductor, and a DC voltage of about 1 to 2 kV is externally applied to the charging member to charge the surface of the photoconductor to a predetermined potential. Things.

However, the direct charging method has a problem that charging tends to be non-uniform. The non-uniformity of the charging is not uniform in each part of the photoreceptor surface, spot-like, or a length of 2 to 200 mm in the longitudinal direction of the photoreceptor,
It causes streak-like charging unevenness with a width of about 0.5 mm or less, and causes white spots and white streaks (phenomena in which white spots and streaks appear on a solid black image) that occur in the case of the normal development method, or the reverse development method. Image defects such as black spots and black streaks (phenomena in which black spots and streaks appear in a solid white image) occur.

In order to improve the uniformity of charging,
A method has been proposed in which a pulsating voltage in which an _AC voltage (VAC) is superimposed on a DC voltage ( _VDC ) is applied to a charging member (JP-A-63-149668). In this case, in order to maintain the uniformity of charging and prevent image defects such as white spots and white streaks or black spots and black streaks, the superimposed AC voltage has a peak-to-peak potential difference (V _PP ) Is necessary.

[0007]

However, in order to prevent image defects, as the superimposed AC voltage is increased, the maximum applied voltage of the pulsating voltage is also increased. Discharge breakdown is more likely to occur. In particular, when the photoconductor is a photoconductor using an organic photoconductor having a low withstand voltage, dielectric breakdown is very likely to occur. In this case, in the normal development method, an image becomes white in the longitudinal direction of the contact portion, and in the reversal development method, a black band occurs.

Moreover, superimposing a V _AC, since the charging member multiplied by the frequency is to contact the electrophotographic photosensitive member, noise was also generated during charging. In addition, an excessive amount of an AC current flows through the electrophotographic photosensitive member, causing electrical deterioration such as an increase in a residual potential, partially damaging the surface of the photosensitive member, and attaching toner and the like to the portion. So-called fusing sometimes occurred.

[0009] Therefore, although method of applying only the V _DC without superimposing V _AC have been reviewed and remains still the problem that nonuniformity of charging as described above.

In addition, with the recent improvement in image quality, the capacity inside the photoreceptor changes due to transfer charging, causing a problem of a so-called transfer memory in which the sensitivity changes depending on whether or not transfer charging has been performed. I have.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor which is free from spot-like or streak-like charging unevenness and has a small potential fluctuation.

Another object of the present invention is to provide an electrophotographic photosensitive member having a small transfer memory.

It is a further object of the present invention to provide a process cartridge and an electrophotographic apparatus having the above electrophotographic photosensitive member and charging means.

[0014]

That is, the present invention relates to an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer has a charge generation layer and a charge transport layer,
The layer is low in isopropylidene and cyclohexylidene
An electrophotographic photosensitive member containing a polycarbonate resin having one of the above structures and being charged by applying only a DC voltage to a charging member in contact with the surface of the electrophotographic photosensitive member.

Further, the present invention is a process cartridge and an electrophotographic apparatus having the above electrophotographic photosensitive member and charging means.

FIG. 1 shows an example of the arrangement of the electrophotographic photosensitive member of the present invention and a charging means. As shown in the figure, the charging member 1 is in contact with the electrophotographic photosensitive member 2 and is connected to an external power source 3.
, The photosensitive member 2 is charged.

The charging member used in the present invention may be any known charging member, and examples thereof include a roller, as shown in FIG. 1, a blade, a brush and a belt. When the charging member is a roller or a blade, a conductive resin such as a metal or an alloy, or a resin that has been subjected to a conductive treatment such as dispersing a carbon black, a metal and a metal oxide, or the like is molded. It can be prepared by drying after coating. Examples of the brush include a magnetic brush using magnetic particles and a fur brush using a brush made of the above-described conductive resin or a resin subjected to conductive treatment.

FIG. 2 shows a specific example of a charging unit for pressing a charging member against a photosensitive member. The roller-shaped charging member 1 can be pressed against the photosensitive member by the action of a spring 5 via a fulcrum 4, and a metal core 6 at the center of the charging member 1 is supplied with a voltage by a contacting power supply brush 7. You. Reference numeral 8 denotes a power receiving connector from the main body, and 9 denotes a support for supporting the charging member 1 to be mounted on the main body along the main body-side guide rail.

FIG. 3 shows an example of the structure of the electrophotographic photosensitive member of the present invention. In the figure, photosensitive layer 1 is placed on conductive support 10.
The photosensitive layer 11 has a charge generation layer 13 containing a charge generation material 12 dispersed in a binder resin and a charge transport layer 14 containing a charge transport material (not shown). In the present invention, the charge transport layer 14 may be stacked on the charge generation layer 13 or may be stacked below the charge generation layer 13, but may be stacked on the charge generation layer in terms of mechanical durability and the like. Is preferred.

Examples of the charge generating substance used in the present invention include pyrylium dyes, thiopyrylium dyes, phthalocyanine pigments, anthantrone pigments, dibenzopyrenequinone pigments, pyratron pigments, azo pigments, indigo pigments, and the like. And quinacridone pigments and quinocyanine dyes. The charge generation layer is obtained by well dispersing the charge generation substance together with a polycarbonate resin and a solvent in an amount of 0.5 to 4 times by a method such as a homogenizer, an ultrasonic wave, a ball mill, a vibration ball mill, a sand mill, an attritor and a roll mill. It is formed by applying the dried dispersion and drying. The thickness is preferably 5 μm or less, particularly preferably 0.01 to 1 μm.

Preferred specific examples of the polycarbonate resin used in the present invention are shown below, but the present invention is not limited thereto. In the examples, n and m indicate the degree of polymerization (molar ratio).

[0022]

[Outside 1]

[0023]

[Outside 2]

The weight average molecular weight of the polycarbonate resin used in the present invention is from 10,000 to 1,000,000.
0, preferably 20,000 to 50
Preferably it is 000.

Examples of the charge transport material used in the present invention include hydrazone compounds, pyrazoline compounds, styryl compounds, oxazole compounds, thiazole compounds, triarylmethane compounds and polyarylalkane compounds.

The charge transport layer 14 is generally formed by applying a solution obtained by dissolving the above-described charge transport material and binder resin in a solvent, followed by drying. The mixing ratio of the charge transport material and the binder resin is about 2: 1 to 1: 2. The thickness of the charge transport layer is preferably from 5 to 30 μm, particularly preferably from 10 to 25 μm.

The binder resin used to form the charge transport layer 14 includes acrylic resin, styrene resin, polyester, polycarbonate resin, polyacrylate, polysulfone, polyphenylene oxide, epoxy resin, polyurethane resin, alkyd resin and non-aqueous resin. Although a saturated resin and the like can be mentioned, in the present invention, a resin having the same monomer unit as the polycarbonate resin used for the charge generation layer is particularly preferable. Further, the weight average molecular weight of the binder resin is preferably from 10,000 to 1,000,000, and particularly preferably from 15,000 to 100,000.

Further, an antioxidant, an ultraviolet absorber, a plasticizer or a known charge transporting substance can be added to the charge transporting layer, if necessary.

Examples of the conductive support used in the present invention include the following.

(1) Aluminum, aluminum alloy,
Metals and alloys such as stainless steel and copper.

(2) Aluminum, on a non-conductive support such as glass, resin and paper or the conductive support of the above (1)
Thin films formed by vapor deposition or lamination of metals and alloys such as aluminum alloy, palladium, rhodium, gold and platinum.

(3) On a non-conductive support such as glass, resin and paper or the conductive support of (1) or (2),
One formed by depositing a conductive substance such as a conductive polymer, tin oxide and indium oxide, or one formed by applying and drying a solution in which these conductive substances are dispersed in an appropriate binder resin.

The conductive support may be in the form of a drum,
Examples thereof include a sheet shape and a belt shape, and it is preferable that the shape is most suitable for the applied electrophotographic apparatus.

In the present invention, an undercoat layer having a barrier function and an adhesive function may be provided between the conductive support and the photosensitive layer. The undercoat layer can be formed of casein, polyvinyl alcohol, nitrocellulose, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, and the like), polyurethane, aluminum oxide, and the like. The thickness of the undercoat layer is 5μ
m, particularly preferably 0.1 to 3 μm.

Further, in the present invention, in order to protect the photosensitive layer from external mechanical and chemical adverse effects, a resin layer as a protective layer, a resin layer containing conductive particles and a charge transporting substance, or the like is used. It can also be provided on a layer.

Examples of the coating method for forming the above-mentioned various layers by coating include a dip coating method, a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, and a blade coating method.

The electrophotographic photosensitive member of the present invention can be used not only for an electrophotographic copying machine but also for a laser beam printer,
It can be widely used in electrophotographic application fields such as CRT printers, LED printers, facsimile machines and electrophotographic plate making systems.

Next, the electrophotographic apparatus of the present invention will be specifically described.

FIG. 4 shows an example of the configuration of the electrophotographic apparatus of the present invention. This apparatus includes a roller-shaped charging member 1, an image exposing unit 15, a developing unit 16, a sheet feeding roller and sheet feeding guide 17, a transfer band unit 18, a cleaning unit 19, and a pre-exposure unit on the peripheral surface of the electrophotographic photosensitive member 2. 20 are arranged.
In the image forming method, first, a DC voltage is applied to the charging member 1 which is arranged in contact with the electrophotographic photosensitive member 2, and the photosensitive member 2 is charged.
Is charged, and an image corresponding to the original is image-exposed on the photoreceptor 2 by the image exposure means 15 to form an electrostatic latent image. Next, the electrostatic latent image on the photoconductor 2 is developed (visualized) by attaching toner to the photoconductor 2 by the developing unit 16.
I do. Further, the toner image formed on the photosensitive member 2 is transferred by a transfer charger 18 onto a transfer material such as paper supplied through a paper feed roller and a paper feed guide 17, and is not transferred to the transfer material by a cleaning unit 19. The remaining toner remaining on the photoconductor 2 is collected. If residual charges remain inside the photoconductor, it is preferable that the photoconductor 2 is exposed to light by the pre-exposure means 20 to eliminate the charge. On the other hand, the transfer material on which the toner image has been formed is sent to a fixing unit (not shown) by a transport unit (not shown), and the toner image is fixed. In this electrophotographic apparatus, the light source of the image exposure means 15 can use halogen light, fluorescent light, laser light, or the like. Other auxiliary processes may be added as needed.

In the present invention, the above-described electrophotographic photosensitive member 2, charging member 1, developing means 16 and cleaning means 1
9 and the like, a plurality of components may be integrally connected as a process cartridge, and the process cartridge may be configured to be detachable from an image forming apparatus main body such as a copying machine or a laser beam printer. . For example, at least one of the charging member 1, the developing unit 16 and the cleaning unit 19 may be integrally supported together with the photoreceptor to form a cartridge, and the process cartridge may be detachable from the apparatus main body by using a guide unit such as a rail of the apparatus main body. Good.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0042]

【Example】

Example 1 A 5% methanol solution of a polyamide resin (trade name: Amilan CM8000, manufactured by Toray Co., Ltd.) was applied on an aluminum cylinder of φ30 mm × 350 mm by an immersion method.
An undercoat layer having a thickness of m was provided.

Next, the following formula:

[0044]

[Outside 3] Of a bisazo pigment represented by the following formula (10 parts by weight, the same applies hereinafter), 10 parts of a polycarbonate resin (Exemplary Compound No. 1, weight average molecular weight of 28,000) and 60 parts of cyclohexane in a sand mill using 1φ glass beads.
Dispersed for 0 hours. To this dispersion was added methyl ethyl ketone 100
The resulting solution was applied on the undercoat layer and dried to form a charge generation layer. The film thickness is 0.12 μm
Met.

Next, the following formula:

[0046]

[Outside 4] 7 parts of a triarylamine compound represented by

[0047]

[Outside 5] 3 parts of a styryl compound represented by a polycarbonate resin (Exemplary Compound No. 1, weight average molecular weight 28,000)
Dissolved in 10 parts and 60 parts of monochlorobenzene. This solution was applied on the charge generation layer and dried to form a charge transport layer. The film thickness after drying was 25 μm.

The obtained electrophotographic photosensitive member was manufactured by Canon NP.
It was attached to -6030. First, a halftone original having a reflection density of 0.45 was placed on an original table with a Macbeth reflection densitometer (manufactured by Macbeth) by applying a DC voltage of -700 V to the charging roller from the outside, and an image was formed. The obtained image was visually observed, and five or more streaks caused by non-uniform charging on the image in the image area for one rotation of the drum were evaluated as x, and 4 to 1 were evaluated as △. And

Further, in this state, the original is changed (the printing rate is 3%).
(Character pattern of about) Performs continuous image output of 10,000 sheets, at the start and at the last bright part potential (hereinafter abbreviated as _VL )
Were measured, | the end of the V _L | - | was V _L the amount of change with | V _L at the start.

Further, V _L when development and transfer were not performed
The absolute value of the difference between _{VL and} when only development was not performed was taken as the transfer memory amount.

Table 2 shows the results.

Examples 2 to 12 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the binder resin for the charge generation layer and the binder resin for the charge transport layer in Example 1 were changed to those shown in Table 1. Was created and evaluated.

In Table 1, Mw indicates a weight average molecular weight.

[0054]

[Table 1]

Examples 13 to 15 In place of the azo pigment of Example 1, X-ray diffraction of CuKα at 9.0 °, 14.2 °, and 2 ° ± 0.2 ° diffraction angles 2θ ± 0.2 °.
Electrophotographic photosensitive members were prepared and evaluated in the same manner as in Examples 1 to 3, except that oxytitanium phthalocyanine having strong peaks at 3.9 ° and 27.1 ° was used. However,
Laserjet III-Si (manufactured by Hewlett-Packard) is used as an electrophotographic apparatus, a halftone document in which black and white are repeated one dot at a time is used as a halftone document, and one dot black and 100 dots are used as a document for continuous image output. A manuscript in which white horizontal lines of dots were repeated was used.

Table 2 shows the results.

Example 16 An undercoat layer was formed on an aluminum cylinder in the same manner as in Example 1 except that the order of the charge generation layer and the charge transport layer was reversed.
The charge transport layer and the charge generation layer were formed in this order. However,
The thickness of the charge generation layer was 0.5 μm.

Further, the following formula

[0059]

[Outside 6] A solution obtained by mixing 25 parts of an acrylic curable monomer, 2.0 parts of 2-methylthioxanthone and 300 parts of toluene is spray-coated on the charge generation layer, dried, and then dried with a high-pressure mercury lamp at 800 mW / cm ² . 20 in light intensity
The protective layer was formed by irradiating ultraviolet rays for 2 seconds. The thickness was 2.0 μm.

The obtained electrophotographic photosensitive member was evaluated in the same manner as in Example 1. However, the charging polarity was positive.

Table 2 shows the results.

Comparative Examples 1-4 Polyvinyl butyral (weight average molecular weight 100,000, butyralization degree 65%) and polymethyl methacrylate (polymethyl methacrylate) were used in place of the polycarbonate resin as the binder resin of the charge generation layer of Example 1. Weight average molecular weight 47,000),
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1, except that a phenoxy resin (weight average molecular weight 30,000) and a cellulose resin (weight average molecular weight 60,000) were used.

Comparative Example 5 An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 13 except that the binder resin of the charge generation layer of Example 13 was changed to that of Comparative Example 1.

Table 2 shows the results.

Comparative Examples 6 and 7 Example 1 except that an AC voltage having a peak-to-peak potential difference of 1.8 kV and a frequency of 400 Hz was superposed on the charging member in addition to the DC voltage.
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Examples 13 and 13.

Table 2 shows the results. Although no streaks due to non-uniform charging were observed in the image after the continuous image formation, image defects due to fusion of the toner occurred.

[0067]

[Table 2]

[0068]

As described above, according to the present invention, an electrophotographic photoreceptor which does not easily cause spot-like or streak-like charging unevenness, has small potential fluctuation, and has a small transfer memory,
A process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of the arrangement of an electrophotographic photosensitive member and a charging unit of the present invention.

FIG. 2 is a diagram illustrating an example of a charging unit for pressing a charging member against an electrophotographic photosensitive member.

FIG. 3 is a diagram illustrating an example of a configuration of an electrophotographic photosensitive member of the present invention.

FIG. 4 is a diagram illustrating an example of the configuration of an electrophotographic apparatus according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 charging member 2 electrophotographic photosensitive member 3 external power supply 4 fulcrum 5 spring 6 cored bar 7 power supply brush 8 power receiving connector 9 support 10 conductive support 11 photosensitive layer 12 charge generating material 13 charge generating layer 14 charge transport layer 15 image exposure Means 16 Developing means 17 Paper feed roller and paper feed guide 18 Transfer charging means 19 Cleaning means 20 Pre-exposure means

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yama ▲ saki ▼ Toshi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hidetoshi Hirano 3-30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Mayumi Kimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-7-225486 (JP, A) JP-A-6- 186758 (JP, A) JP-A-6-75390 (JP, A) JP-A-5-289371 (JP, A) JP-A-4-368956 (JP, A) JP-A-5-45915 (JP, A) JP-A-4-360148 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/05

Claims (6)

(57) [Claims] 1. An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer comprises a charge generation layer and a charge transport.
Layer, wherein the charge generation layer is
It contains a polycarbonate resin having at least one structure of hexylidene, and is charged by applying only a DC voltage to a charging member in contact with the surface of the electrophotographic photosensitive member. Electrophotographic photoreceptor. 2. The electrophotographic photoconductor according to claim 1, wherein the electrophotographic photoconductor has a charge generation layer on a conductive support, and has a charge transport layer on the charge generation layer. 3. An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer comprises a charge generation layer and a charge transport.
Layer, wherein the charge generation layer is
An electrophotographic photosensitive member containing a polycarbonate resin having at least one structure of hexylidene, and being charged by applying only a DC voltage to a charging member in contact with the surface of the electrophotographic photosensitive member, And a process cartridge, wherein at least one means selected from the group consisting of a charging means having a charging member, a developing means and a cleaning means is integrally supported and is detachable from the main body of the electrophotographic apparatus. 4. The process cartridge according to claim 3, wherein said electrophotographic photosensitive member has a charge generation layer on a conductive support, and has a charge transport layer on said charge generation layer. 5. An electrophotographic apparatus having an electrophotographic photosensitive member, a charging unit having a charging member, an image exposing unit, a developing unit and a transfer unit, wherein the electrophotographic photosensitive member has a photosensitive layer on a conductive support. A photoreceptor, wherein the photosensitive layer is
A charge generation layer and a charge transport layer, wherein the charge generation layer
At least one of propylidene and cyclohexylidene
The charging member contacts the surface of the electrophotographic photoreceptor,
An electrophotographic apparatus, wherein the electrophotographic photosensitive member is charged by applying only the electrophotographic photosensitive member. 6. The electrophotographic apparatus according to claim 5, wherein the electrophotographic photosensitive member has a charge generation layer on a conductive support, and has a charge transport layer on the charge generation layer.