JP3337747B2 - Electrophotographic photoreceptor and electrophotographic apparatus having the same - 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 photoreceptor, and more particularly to an electrophotographic photoreceptor capable of obtaining a high-quality image in an electrophotographic apparatus having a direct charge transfer means.

[0002] The present invention also relates to an electrophotographic apparatus having the above electrophotographic photosensitive member.

[0003]

2. Description of the Related Art As a charging member in an electrophotographic apparatus,
Conventionally used corona chargers have a problem that the photoreceptor is deteriorated by ozone generated at the time of discharge, and an electrophotographic apparatus employing a direct charging method as an alternative means is being put to practical use. It has become In this method, charging is performed by applying a voltage to a low-resistance member in contact with an electrophotographic photosensitive member.

In the case where transfer charging is performed by direct charging, there is a problem that a central portion of a toner image to be transferred easily remains on a photosensitive member. This is a so-called "hollow-out" phenomenon of the toner image, and causes a reduction in image quality.

It is considered that this hollowing occurs because the charging member presses the toner image formed on the surface of the photoconductor to the photoconductor via the transfer material. As means for improving this, studies have been made in terms of the toner prescription and the transfer process, but they are not always sufficient, and harmful effects cannot be avoided.

[0006]

That is, an object of the present invention is to provide an electrophotographic photoreceptor and an electrophotographic apparatus which can improve the above-mentioned drawbacks and greatly improve the void phenomenon of a toner image in a direct charge transfer system. Aim.

[0007]

That is, the present invention relates to an electrophotographic photosensitive member used in an electrophotographic apparatus having a transfer means for transferring a toner image to a transfer material by direct charging.
The electrophotographic photoreceptor has a charge generation layer on a conductive support,
An electrophotographic photosensitive member having a transport layer and a surface layer in this order.
Thus, the charge transport layer comprises a charge transport material and polycarbonate.
And the surface layer is made of a powder and powder of a fluoropolymer.
Containing polycarbonate, which is an electrophotographic photosensitive member, wherein the contact angle for water of the surface of the electrophotographic photosensitive member is less than 110 °.

Further, the present invention is an electrophotographic apparatus having the above electrophotographic photosensitive member.

In order to reduce the void in the toner image, for example, in the development process, it is necessary to optimize the thickness of the developed toner layer, the fluidity of the toner, and the like. On the transfer process side, there are factors such as the contact pressure of the charging member against the photoconductor, the rush angle of the transfer material, and the peripheral speed difference between the charging member and the photoconductor. However, as described above, there are problems that the effects are insufficient only by these conditions, and that harmful effects cannot be avoided.

On the other hand, from the viewpoint of the photoreceptor, the present inventors have found that the releasability of the surface on which a toner image is formed has a particularly large effect in the case of direct charge transfer. That is, it was found that when the releasability of the photoreceptor surface was 110 ° or more in terms of the contact angle with water, excellent transfer characteristics were exhibited, and there was a great effect on hollowing out.

The present invention is effective when the surface of the photoreceptor is mainly composed of a polymer binder.

As means for imparting releasability to such a surface layer, a resin having a low surface energy is used for the resin constituting the film, an additive for imparting water / oil repellency is added, And dispersing the material having releasability into a powdery state.

[0013] Te present invention smell, fluoropolymer, e.g., polytetrafluoroethylene, dispersed powder, such as polyvinylidene fluoride are preferred.

Next, an example of a specific embodiment of the electrophotographic photosensitive member will be described.

The photoreceptor of the present invention has a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material. The charge generating layer and the charge transporting layer are laminated in this order from the support side. , Ru further Monodea provided with a protective layer thereon.

As the conductive support, aluminum,
Examples thereof include metals such as stainless steel, plastics provided with a conductive layer, paper, and the like, and examples of the shape include a cylindrical shape and a film shape.

An undercoat layer having a barrier function and an adhesive function can be provided between the support and the photosensitive layer. The undercoat layer is used for improving the adhesiveness of the photosensitive layer, improving the coating property, protecting the support, covering defects on the support, improving the charge injection property from the support, protecting the photosensitive layer from electrical breakdown, etc. Form. Examples of the material for the undercoat layer include polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide,
Ethyl cellulose, polyamide, copolymerized nylon, ethylene-acrylic acid copolymer and the like are known. These are each dissolved in a suitable solvent and applied on a support.
Its thickness is about 0.1 to 2.0 μm.

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

The charge generation layer is provided on the undercoat layer. Examples of the charge generation layer include those formed by coating an inorganic photoconductor such as amorphous silicon or selenium with a binder as necessary, forming the coating, or forming by vacuum evaporation. In the case of an organic material, one or two or more kinds of charge generating materials such as azo pigments, quinone pigments, perylene pigments and phthalocyanine pigments can be deposited or dispersed together with a suitable binder, and formed by coating. .

The charge transport layer is formed by dissolving a charge transport material in a solvent together with a binder. Examples of organic charge transport materials include hydrazone-based compounds, stilbene-based compounds,
Pyrazoline compounds, oxazole compounds, triarylamine compounds and the like can be mentioned. These charge transport materials can be used alone or in combination of two or more.

The binder of the charge transport layer of the present invention is polycarbonate.

The thickness of the charge transport layer is 5 to 50 μm, preferably 10 to 30 μm, and the weight ratio of the charge transport material to the binder is 5: 1 to 1: 5, preferably 3: 1 to 1 : 3
It is about.

On the charge transport layer, the contact angle with water is 1
A surface layer of 10 ° or more is provided. The composition is poly
A powder of, for example, polytetrafluoroethylene is dispersed in carbonate . The amount of such a low surface energy imparting agent to be added to the entire surface layer is 10 to 100% by weight, preferably 20 to 50% by weight. If the amount is less than 10% by weight, the effect of the present invention may be insufficient,
If it exceeds 00% by weight, the film strength of the surface layer tends to decrease, so that the durability in repeated use may decrease. If necessary, a charge transporting material may be added to improve the potential characteristics.

The contact angle was measured using a contact angle meter CA-DS, Kyowa Interface Chemical Co., Ltd.

FIG. 1 shows a schematic configuration example of an electrophotographic apparatus using the electrophotographic photosensitive member of the present invention.

In FIG. 1, reference numeral 1 denotes a drum type photosensitive member of the present invention as an image carrier, which is driven to rotate around an axis 1a in a direction indicated by an arrow at a predetermined peripheral speed. The photoreceptor 1 is uniformly charged with a predetermined positive or negative potential on its peripheral surface by a charging means 2 during the rotation process, and then, in an exposure section 3, a light image exposure L (slit exposure / Laser beam scanning exposure). As a result, an electrostatic latent image corresponding to the exposure image is sequentially formed on the peripheral surface of the photoconductor.

The electrostatic latent image is then developed with toner by developing means 4, and the developed toner image is transferred by a transfer means 5 from a paper feeding unit (not shown) to the photosensitive body 1 between the photosensitive body 1 and the transfer means 5. The transfer material P is sequentially transferred onto the surface of the transfer material P which is synchronously taken out and fed.

The transfer material P which has undergone the image transfer is separated from the photoreceptor surface, introduced into the image fixing means 8 and subjected to image fixing to be printed out as a copy (copy) outside the machine.

The surface of the photoreceptor 1 after the image is transferred is cleaned by a cleaning unit 6 to remove the untransferred toner, and is further subjected to a static elimination process by a pre-exposure unit 7 to be used repeatedly for image formation.

As the uniform charging means 2 for the photoreceptor 1, a corona charging device is generally widely used, but a direct charging device in which a charging member is brought into contact as described above is also used. Further, since the transfer device 5 is a direct charging system in the present invention,
Here, a conductive roller is pressed against the photoconductor. As an electrophotographic apparatus, a plurality of components such as the above-described photoreceptor, developing means, and cleaning means are integrally connected as an apparatus unit, and this unit is configured to be detachable from the apparatus body. May be. For example, the photoreceptor 1 and the cleaning means 6 may be integrated into one apparatus unit, and may be configured to be detachable using guide means such as rails of the apparatus body. At this time, the above-described device unit may be provided with a charging unit and / or a developing unit.

In the case where the electrophotographic apparatus is used as a copier or a printer, the light image exposure L is performed by scanning a laser beam on the basis of the signal reflected from or transmitted from the original or a read signal of the original. Or by driving an LED array or a liquid crystal shutter array.

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

The controller 11 controls the image reading unit 10 and the printer 19. The whole controller 11 is CP
It is controlled by U17. The read data from the image reading unit 10 is transmitted to the partner station through the transmission circuit 13. Data received from the partner station is sent to the printer 19 through the receiving circuit 12. The image memory 16 stores predetermined image data. The printer controller 18 controls a printer 19. 14 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 and then decoded by the CPU 17, and is sequentially stored in the image memory 16. Is stored. When the image information of at least one page is stored in the memory 16, the image of the page is recorded. The CPU 17 reads one page of image information from the memory 16 and sends the decoded one page of image information to the printer controller 18. Upon receiving the image information of one page from the CPU 17, the printer controller 18 controls the printer 19 to record the image information of the page.

The CPU 17 receives the next page during recording by the printer 19.

As described above, image reception and recording are performed.

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,
RT printer, LED printer, LCD printer,
It can be widely used in electrophotographic applications such as laser plate making.

[0038]

Next, the present invention will be described with reference to examples.

Example 1 A coating composed of the following materials was applied on a support of an Al cylinder having a diameter of 30 mm and 260 mm by an immersion method.
The composition was thermally cured at 30 ° C. for 30 minutes to form an 18 μm conductive layer.

Conductive pigment: Tin oxide / antimony oxide coating Treated titanium oxide: 10 parts (parts by weight, hereinafter the same) Resistance adjusting pigment: Titanium oxide: 10 parts Binder resin: phenolic resin: 10 parts Leveling agent: silicone oil ... 0.001 part Solvent: methanol / methyl cellosolve = 1/1 ... 20 parts Next, 3 parts of N-methoxymethylated nylon and 3 parts of copolymerized nylon are mixed with 65 parts of methanol and 30 parts of n-butanol. 0.5μ by applying the solution dissolved in
m undercoat layer was formed.

Next, 4 parts of an azo pigment having the following structural formula:

[0042]

Embedded image

After 2 parts of a polyvinyl butyral resin and 80 parts of cyclohexanone were dispersed in a sand mill using φ1 mm glass beads for 6 hours, 100 parts of THF was added to obtain a dispersion for a charge generation layer. This was applied on the undercoat layer by an immersion method to form a 0.2 μm charge generation layer.

Next, 10 parts of the following charge transporting material

[0045]

Embedded image

10 parts of a polycarbonate Z resin were dissolved in 50 parts of monochlorobenzene and 10 parts of dichloromethane.
This paint is applied on the charge generation layer by the dipping method,
A 0 μm charge transport layer was formed.

Next, 2.5 parts of polytetrafluoroethylene powder was dispersed in monochlorobenzene together with 5.5 parts of a polycarbonate Z resin, and 2 parts of the above-described charge transport material were dissolved therein. This was applied on the charge transport layer by a spray method to form a 3 μm surface layer.

The photosensitive member thus obtained was mounted on a laser beam printer LBP-NX (manufactured by Canon Inc.), and the image was evaluated. In this printer, transfer is performed by bringing a conductive rubber roller into contact with a photosensitive member at a total pressure of 1400 g and applying a DC bias of 2 KV between the roller and the photosensitive member.

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1, except that the thickness of the charge transport layer was 23 μm and no surface layer was provided. Images of the obtained photoreceptors were similarly evaluated.
Table 1 shows the results.

The evaluation of the void was made by measuring the toner concealing rate in the character image (alphabet), and ranking was performed. As is clear from these results, the photoreceptor of the present invention has a remarkable effect on hollowing out.

Example 2 A conductive layer and an undercoat layer were provided in the same manner as in Example 1 on a support of an Al cylinder having a diameter of 30 mm and 346 mm. Next, 4 parts of an azo pigment having the following structural formula,

[0052]

Embedded image

After 2 parts of a polyvinyl butyral resin and 80 parts of cyclohexanone were dispersed in a sand mill using φ1 mm glass beads for 6 hours, 100 parts of THF was added to obtain a dispersion for a charge generation layer. This was applied on the undercoat layer by an immersion method to form a 0.2 μm charge generation layer.

Next, 10 parts of the following charge transporting material

[0055]

Embedded image

10 parts of a polycarbonate Z resin were dissolved in 50 parts of monochlorobenzene and 10 parts of dichloromethane.
This paint is applied on the charge generation layer by the dipping method,
A 2 μm charge transport layer was formed.

Next, 3 parts of polytetrafluoroethylene powder were dispersed in monochlorobenzene together with 5 parts of polycarbonate Z resin, and 2 parts of the above-described charge transporting material were dissolved therein. This is applied on the charge transport layer by a spray method,
A μm surface layer was formed.

The obtained photoreceptor was transferred to a plain paper copying machine NP-2.
The evaluation was carried out by mounting the transfer mechanism 020 on a roller modified to the same roller transfer system as the printer used in Example 1. Table 1 shows the results.

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[Table 1]

[0069]

The photoreceptor of the present invention, as a photoreceptor used in a direct charge transfer type electrophotographic apparatus, can provide a high quality image with few voids.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus of the present invention.

FIG. 2 is a block diagram of a facsimile using the electrophotographic apparatus as a printer.

[Description of Signs] 1 Photoconductor 2 Charging means 3 Exposure unit 4 Developing means 5 Transfer means 6 Cleaning means 7 Pre-exposure means 8 Image fixing 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 Hideyuki Ainoya 3-30-2 Shimomaruko, Ota-ku, Tokyo No. Canon Inc. (72) Inventor Hidetoshi Hirano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A 1-243067 (JP, A) JP-A 4- 130486 (JP, A) JP-A-63-43162 (JP, A) JP-A-4-181963 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/05 G03G 5 / 147 G03G 15/16

Claims (2)

(57) [Claims] An electrophotographic photosensitive member used in an electrophotographic apparatus having a transfer means for transferring a toner image to a transfer material by direct charging, wherein the electrophotographic photosensitive member is provided on a conductive support.
An electrode having a charge generation layer, a charge transport layer and a surface layer in this order.
An electrophotographic photoreceptor, wherein the charge transport layer comprises a charge transport material and
And polycarbonate, and the surface layer is a fluorine-containing poly
Containing powder and polycarbonate mer, the electrophotographic photosensitive member, wherein the contact angle for water of the electrophotographic <br/> photoconductor surface is 110 ° or more. 2. An electrophotographic apparatus comprising: a transfer unit for transferring a toner image to a transfer material by direct charging; and an electrophotographic photosensitive member according to claim 1.