JPH0675416A - Electrophotographic sensitive body, and electrophotographic device and device unit using that electrophotographic body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having excellent electrophotographic characteristics with which an excellent picture image is stably obtd. even the photosensitive body is repeately used, and to provide an electrophotographic device and a device unit using this electrophotographic sensitive body. CONSTITUTION:This electrophotographic sensitive body has a photosensitive layer containing a binder resin and a surface layer containing resin particles containing fluorine atoms, charge transfer material, and binder resin. Both binder resins in the surface layer and the photosensitive layer have the same structural component. The binder resin in the surface layer has 50000-160000 number average mol.wt., while the binder resin in the photosensitive layer has 10000-50000 number average mol.wt. Further, the number average mol.wt. of the binder resin in the surface layer is twice or more as that of the binder resin in the photosensitive layer. The electrophotographic device and the device unit uses this electrophotographic sensitive body.

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 having a specific surface layer. The present invention also relates to an electrophotographic apparatus and apparatus unit having the above electrophotographic photosensitive member.

[0002]

2. Description of the Related Art Needless to say, an electrophotographic photosensitive member has required sensitivity, electric characteristics and optical characteristics according to an electrophotographic process to be applied, but further, the photosensitive member is repeatedly used. Are required to have durability against electric and mechanical external forces such as charging, development, transfer and cleaning. Specifically, durability against scratches and scratches on the surface of the photoconductor due to rubbing and deterioration of the photoconductor due to ozone and NOx is required. In addition, it is also necessary to have an excellent cleaning property in order to prevent toner from adhering to the surface of the photoconductor.

In order to satisfy such characteristics, it is known to provide a surface protective layer containing a resin as a main component on the photosensitive layer. For example, JP-A-62-272228 proposes to improve mechanical properties and potential stability by adding fluorine resin particles and a charge transport material to a protective layer.

On the other hand, in general, a film formed by using a resin having a small molecular weight has good adhesion to other layers, but has a low hardness and tends to have poor durability. On the other hand, since a film formed using a resin having a large molecular weight tends to have a large internal stress, when a layer having a relatively large thickness such as a photosensitive layer is formed, cracks may occur in the film, The film itself becomes fragile.

With the recent demand for higher image quality and higher durability, electrophotographic photoreceptors having better electrophotographic characteristics and better durability have been investigated.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member which has excellent electrophotographic characteristics and which can stably obtain an excellent image even when it is repeatedly used. .

The present invention also provides an electrophotographic apparatus and an apparatus unit having the electrophotographic photosensitive member.

[0008]

That is, the present invention is an electrophotographic photosensitive member having a photosensitive layer on a conductive support and a surface layer on the photosensitive layer, wherein the photosensitive layer generates a charge. In the electrophotographic photoreceptor containing a substance, a charge transporting substance and a binder resin, and the surface layer containing fluorine atom-containing resin particles, a charge transporting substance and the binder resin, the constitution of the binder resin contained in the surface layer And the binder resin contained in the photosensitive layer has the same constituents, and the binder resin contained in the surface layer is 50,00.
The number of binder resins having a number average molecular weight of 0 to 160,000, the binder resin contained in the photosensitive layer having a number average molecular weight of 10,000 to 50,000, and the surface layer containing An electrophotographic photosensitive member characterized in that the average molecular weight is at least twice the number average molecular weight of the binder resin contained in the photosensitive layer.

The present invention is also an electrophotographic apparatus and apparatus unit having the electrophotographic photosensitive member.

In the present invention, since the constituent components of the resin contained in the surface layer and the constituent components of the resin contained in the photosensitive layer are the same, as compared with the case where different kinds of resins are used in the respective layers, Since the interface between the surface layer and the photosensitive layer does not occur,
Adhesion between both layers is high, distortion is unlikely to occur, it is possible to use a high molecular weight resin for the surface layer, durability can be significantly improved and carrier traps at the interface are also very small Therefore, the electrical characteristics can be improved.

On the other hand, in the present invention, since the number average molecular weight of the resin contained in the surface layer is more than twice the number average molecular weight of the resin contained in the photosensitive layer, an appropriate interface is formed, so that the charge between both layers is charged. Migration of transport materials and the like is less likely to occur, a very uniform surface layer and photosensitive layer can be formed, and as a result, a superior image can be obtained. If the amount is less than twice, the layers will be too compatible with each other and the surface condition of the layers will become non-uniform, and the non-uniformity of the potential characteristics and the increase of the residual potential due to migration of the charge-transporting substance are likely to occur. .

Further, in the present invention, since the surface layer contains Teflon, it is possible to provide an electrophotographic photoreceptor having high surface lubricity and extremely excellent durability.

The photosensitive layer of the electrophotographic photoreceptor of the present invention contains a charge-generating substance, a charge-transporting substance and a binder resin, but a so-called single layer type containing the charge-generating substance and the charge-transporting substance in the same layer. And a charge-generating layer containing a charge-generating substance and a charge-transporting layer containing a charge-transporting substance. The laminated type further includes a conductive support, a type having a charge generation layer and a charge transport layer in this order, and a conductive support,
It is classified into a type having a charge transport layer and a charge generation layer. In the present invention, the laminated type, particularly the type in which the charge transport layer is laminated on the charge generation layer, is most preferable.

When the photosensitive layer is of a laminated type, the charge generation layer comprises an inorganic charge generation material such as selenium, selenium-tellurium and amorphous silicon; pyrylium dye, thiapyrylium dye, azulenium dye, thiacyanine dye and quinocyanine dye. Cationic dyes such as dyes; Squarium salt dyes; Phthalocyanine pigments; Antoanthrone pigments; Polybenzquinone pigments such as dibenzpyrenequinone pigments and pyrantrone pigments; Indigo pigments; Quinacridone pigments and azo pigments A material selected from the above is contained as a charge generating substance. These can be used alone or in combination. The charge generation layer may be formed as a vapor deposition layer on a conductive support by a vacuum vapor deposition device, or a liquid in which the above charge generation substance is dispersed in a binder resin using an appropriate solvent is applied and dried. Can be formed as a coating layer.

As the binder resin, a wide range of insulating resins such as polyvinyl butyral, polyarylate (polycondensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, polyvinyl acetate, acrylic resin, polyacrylamide, Examples thereof include resins such as polyamide, cellulosic resin, urethane resin, epoxy resin and polyvinyl alcohol.
Mention may also be made of organic photoconductive resins such as N-vinylcarbazole and polyvinylpyrene. The proportion of the binder resin in the charge generation layer is preferably 90% by weight or less, and particularly preferably 50% by weight or less, based on the total weight of the charge generation layer. However, in the case of the type in which the charge generation layer is formed on the charge transport layer, the charge generation layer must contain a binder resin, and the ratio thereof is 10% by weight based on the total weight of the charge generation layer. Or more is preferable,
It is particularly preferably 30% by weight or more.

The thickness of the charge generation layer is 0.001 to
It is preferably 6 μm, particularly 0.01 to 1 μm
Is preferred.

The charge transport layer comprises a polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene and phenanthrene in the main chain or side chain; a nitrogen-containing ring compound such as indole, carbazole, oxadiazole and pyrazoline; hydrazone compound. And a styryl compound or other charge-transporting substance are dissolved in a binder resin using a suitable solvent, and the resultant is formed by coating and drying.

Examples of the binder resin that can be used include polyarylate, polysulfone, polyamide, acrylic resin, acrylonitrol resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester, alkyd resin, and polycarbonate. , Polyurethane, styrene-butadiene copolymer, styrene-acrylic copolymer, styrene-acrylonitrile copolymer and styrene-maleic acid copolymer. In addition to such an insulating resin, an organic photoconductive polymer such as polyvinylcarbazole, polyvinylanthracene or polyvinylpyrene can also be used. Of these, acrylic resins, methacrylic resins, polycarbonates and styrene-acrylic copolymers are particularly preferred. The compounding ratio of the binder resin and the charge transport material is preferably 20 to 80% by weight of the charge transport material with respect to the total weight of the charge transport layer.
It is particularly preferably 30 to 70% by weight.

The thickness of the charge transport layer is 10 to 35 μm.
It is preferably m, and particularly preferably 15 to 30 μm.

When the photosensitive layer is of a single layer type, a liquid obtained by dispersing and dissolving the above-mentioned charge generating substance and charge transporting substance in the above-mentioned binder resin is coated on a conductive support and dried. Can be formed.

At this time, the thickness of the photosensitive layer is 10 to 35 μm.
Is preferable, and particularly preferably 15 to 30 μm.

In the present invention, whichever type of photosensitive layer is used, the number average molecular weight of the binder resin contained in the layer in contact with the surface layer is 10,000 to 50,0.
00, preferably 15,000 to 40,000.

On the other hand, the surface layer of the electrophotographic photosensitive member of the present invention contains fluorine-containing resin particles, a charge transport substance and a binder resin.

As such fluorine atom-containing resin particles,
Polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polydichlorodifluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer Examples thereof include a combination and a tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer. These resin particles can be used alone or in combination of two or more kinds. The molecular weight is the number average molecular weight,
It is preferably 3,000 to 5,000,000, and particularly preferably 10,000 to 3,000,000. The average particle size is 0.01 to 10 μm.
Is preferable, and particularly preferably 0.05 to 2.0 μm.

In the present invention, it is preferable that the surface layer contains a large amount of the above resin particles from the viewpoint of improving lubricity, but in order to minimize the scattering of light by the resin particles, the surface layer should contain as little as possible. Preferably.
Specifically, the resin particles account for 30 to 7 relative to the total weight of the surface layer.
It is preferably 0% by weight, particularly preferably 40 to 65% by weight.

The charge transport material contained in the surface layer is as follows.
The same as those contained in the photosensitive layer can be mentioned.

The binder resin contained in the surface layer may be the same as the binder resin contained in the photosensitive layer. In the present invention, the binder resin contained in the surface layer has a constituent component of the surface layer. Is the same as the constituent component of the binder resin contained in the photosensitive layer in contact with, and has a molecular weight of 50 in terms of number average molecular weight,
000 to 160,000, preferably 60,000
It is 0 to 100,000. Furthermore, in the present invention,
It is at least twice the number average molecular weight of the binder resin contained in the photosensitive layer in contact with the surface layer. Considering the distortion of the interface between the surface layer and the photosensitive layer, and cracks in the surface layer, the number average molecular weight of the resin contained in the surface layer is the number average molecular weight of the resin contained in the photosensitive layer in contact with the surface layer. It is preferably 6 times or less. Incidentally, when the resin is a copolymer, the constituent components of the resin indicate a plurality of monomer units contained in the copolymer, and the copolymerization ratio of the resin contained in the surface layer and the resin contained in the photosensitive layer. The copolymerization ratios of the above may be the same or different, but the same is more preferable.

For the surface layer in the present invention, a liquid obtained by dispersing and dissolving the above-mentioned fluorine atom-containing resin particles and the charge transporting substance in the above-mentioned binder resin using a suitable solvent is coated on the photosensitive layer and dried. Can be formed by
The film thickness is preferably 0.05 to 10 μm, and particularly preferably 0.5 to 8 μm.

Examples of the conductive support used in the present invention include aluminum, aluminum alloys, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold and platinum. In addition, a plastic (for example, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, and the like) coated with such a metal or alloy by a vacuum deposition method and conductive particles (for example, carbon black and silver particles) are appropriately bonded. It is possible to use the above-mentioned plastic, a support coated on a metal or alloy support, or a support obtained by impregnating plastic or paper with conductive particles together with the resin. Examples of the shape of the support include a drum shape, a sheet shape, and a belt shape, but it is preferable that the shape is most suitable for the electrophotographic apparatus to be applied.

In the present invention, a layer containing a resin as a main component, a so-called subbing layer, may be provided between the conductive support and the photosensitive layer. The undercoat layer has the function of controlling the injection of carriers from the conductive support and improving the adhesion between the support and the photosensitive layer. The undercoat layer is mainly made of resin, but may contain the above-mentioned metals, alloys, their oxides, salts and surfactants. Specific examples of the resin used for the undercoat layer include polyester, polyurethane, polyarylate, polyethylene, polystyrene, polybutadiene, polycarbonate, polyamide, polypropylene, polyimide, phenol resin, acrylic resin, silicone resin, epoxy resin, urea resin, allyl. resin,
Examples thereof include alkyd resin, polyamide-imide, nylon, polysulfone, polyallyl ether, polyacetal and butyral resin. The film thickness is 0.05-7μ
It is preferably m, and particularly preferably 0.1 to 2 μm.

Examples of the method for applying the various layers described above include a dip coating method, a spray coating method, a beam coating method, a spinner coating method, a roller coating method, a Mayer bar coating method and a blade coating method.

The electrophotographic photoreceptor of the present invention can be applied to general electrophotographic apparatuses such as copying machines, laser printers, LED printers and liquid crystal shutter type printers.
Further, it can be widely applied to devices such as displays, recording, light printing, plate making and facsimiles to which electrophotographic technology is applied.

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

In the figure, reference numeral 1 denotes a drum type photosensitive member as an image bearing member, which is rotationally driven around a shaft 1a in a direction of an arrow at a predetermined peripheral speed. The photosensitive member 1 receives uniform charging of a positive or negative predetermined potential on the peripheral surface of the photosensitive member 1 by the charging unit 2 during its rotation process, and then an optical image exposure L (slit exposure) by an image exposing unit (not shown) in the exposure unit 3.・ Receive laser beam scanning exposure. As a result, electrostatic latent images corresponding to the exposed image are sequentially formed on the peripheral surface of the photoconductor.

The electrostatic latent image is then toner-developed by the developing means 4, and the toner-developed image is synchronized with the rotation of the photoconductor 1 between the photoconductor 1 and the transfer means 5 from a paper feeding section (not shown). The transfer material P is sequentially transferred to the transferred and fed transfer material P.

The transfer material P which has received the image transfer is separated from the surface of the photoconductor and is introduced into the image fixing means 8 where it is subjected to the image fixing and printed out as a copy.

After the image transfer, the surface of the photoconductor 1 is cleaned by the cleaning means 6 to remove the residual toner after transfer, and is further discharged by the pre-exposure means 7 to be repeatedly used for image formation. It

As the uniform charging means 2 for the photosensitive member 1, a corona charging device is generally widely used. In addition, the transfer device 5
Corona transfer means are also widely used. In the present invention, among the above-described components such as the photoconductor, the developing unit, and the cleaning unit, a plurality of components are integrally combined and configured as an apparatus unit, and this unit is configured to be detachable from the apparatus main body. May be. For example, at least one of a charging unit, a developing unit, and a cleaning unit is integrally supported together with a photoconductor to form a unit, which is a detachable single unit in the main body of the apparatus and a guide unit such as a rail of the main body of the apparatus is used. It may be detachable.

When the electrophotographic apparatus is used as a copying machine or a printer, the light image exposure L irradiates the photoconductor with reflected light or transmitted light from the original, or the original is read by a sensor and converted into a signal. According to this signal, the laser beam is scanned, the LED array is driven, or the liquid crystal shutter array is driven to irradiate the photoconductor with light.

When used as a facsimile printer, the optical image exposure L becomes an exposure for printing the 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 CP
It is controlled by U17. The read data from the image reading unit is transmitted to the partner station through the transmission circuit 13. The data received from the partner station is sent to the printer 19 through the receiving circuit 12. Predetermined image data is stored in the image memory. The printer controller 18 is the printer 1
9 is controlled. 14 is a telephone.

The image received from the line 15 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 12, and then the CPU 17 decodes the image information and sequentially processes the image memory 16. Stored in. Then, when at least one page of image is stored in the memory 16,
The image of that page is recorded. CPU 17 is a memory 1
The image information of one page is read from 6 and the decoded image information of one page is sent to the printer controller 18. The printer controller 18 is the one from the CPU 17.
When the image information of the page is received, the printer 19 is controlled to record the image information of the page.

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

Images are received and recorded as described above.

[0045]

【Example】

Example 1 10 parts by weight of nylon (M-4000, manufactured by Toray Industries, Inc.), 100 parts by weight of methanol and 90 parts of isopropanol
By dipping the solution dissolved in the mixed solution of 1 part by weight onto an aluminum cylinder having an outer diameter of 80 mm, a wall thickness of 1.5 mm and a length of 363 mm, and drying at 90 ° C. for 20 minutes, a film thickness of 2.0 μm is obtained. A pull layer was formed.

Next, a trisazo pigment 1 represented by the following formula
0 parts by weight,

[0047]

[Outer 1] A solution for charge generation layer was obtained by adding 5 parts by weight of polycarbonate (bisphenol A type, number average molecular weight of 20,000) to 600 parts by weight of cyclohexanone and dispersing using a sand mill. This solution was applied onto the undercoat layer by dip coating and dried at 120 ° C. for 20 minutes to form a charge generation layer having a film thickness of 0.15 μm.

Then, 20 parts by weight of a compound represented by the following formula:

[0049]

[Outside 2] And polycarbonate (bisphenol Z type, number average molecular weight 16,000) 20 parts by weight with chlorobenzene 800
A solution for a charge transport layer was obtained by dissolving in a weight part using a ball mill. This solution was applied onto the charge generation layer by dip coating and dried at 130 ° C. for 90 minutes to form a charge generation layer having a thickness of 18 μm.

Next, 10 parts by weight of polytetrafluoroethylene particles (Lubron L-2, manufactured by Daikin Industries, Ltd.) were added to polycarbonate (bisphenol Z type, Mn8).
5,000) 10 parts by weight and 5 parts by weight of a compound represented by the following formula

[0051]

[Outside 3] Was added to a solution of 450 parts by weight of dichloromethane,
A surface layer solution was obtained by dispersing with a sand mill. This solution is applied onto the charge transport layer by dip coating.
By drying at 0 ℃ for 30 minutes, the film thickness becomes 2.0μ.
m surface layer was formed.

The electrophotographic photosensitive member thus obtained was mounted on a full-color copying machine (CLC-500, manufactured by Canon Inc.), and a durability test of 20,000 images was carried out.
The evaluation of the electric potential characteristics is performed in the dark part potential (V
_D ), bright part potential ( _VL ) and residual potential (Vr: potential after pre-exposure) were compared. In addition, the obtained image was visually evaluated. The dark part potential and the light part potential in the initial stage were set to -700V and -200V, respectively. The results are shown in Table 1.

Examples 2 to 5 and Comparative Examples 1 to 3 An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the resins used in the charge transport layer and the surface layer had the number average molecular weights shown in Table 1. Created and evaluated. The results are shown in Table 1.

Comparative Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the surface layer was not provided and the thickness of the charge transport layer was 20 μm.
evaluated. The results are shown in Table 1.

[0055]

[Table 1]

Example 6 The resin contained in the charge transport layer and the surface layer was polymethylmethacrylate, and each had a number average molecular weight of 25,000.
And an electrophotographic photosensitive member were prepared and evaluated in the same manner as in Example 1 except that the amount was 100,000. The results are shown in Table 2.

Examples 7 to 10 and Comparative Examples 5 to 7 Electrophotographic photoreceptors were prepared in the same manner as in Example 6 except that the resins used in the charge transport layer and the surface layer had the number average molecular weights shown in Table 2. Created and evaluated. The results are shown in Table 2.

[0058]

[Table 2]

Example 11 The resin contained in the charge transport layer and the surface layer was represented by the following formula.

[0060]

[Outside 4] Styrene-methylmethacrylate copolymer represented by
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the value was set to 10,000. The results are shown in Table 3.

Examples 12 to 15, Comparative Examples 8 and 9 An electrophotographic photosensitive member was prepared in the same manner as in Example 11 except that the resins used in the charge transport layer and the surface layer had the number average molecular weights shown in Table 3. Created and evaluated. The results are shown in Table 3.

Comparative Example 10 An electrophotographic photosensitive member was prepared in the same manner as in Example 11 except that polytetrafluoroethylene particles were not used.
evaluated. The results are shown in Table 3.

[0063]

[Table 3]

[0064]

As described above, according to the present invention, an electrophotographic photosensitive member having excellent electrophotographic characteristics and capable of stably obtaining an excellent image even when repeatedly used, and the electrophotographic photosensitive member It is possible to provide an electrophotographic apparatus and an apparatus unit having the above.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus having an electrophotographic photosensitive member of the present invention.

FIG. 2 is a diagram showing an example of a block diagram of a facsimile having the electrophotographic photosensitive member of the present invention.

[Explanation of symbols]

 1 Electrophotographic Photoreceptor of the Present Invention 1a Axis 2 Charging Means 3 Exposure Unit 4 Developing Means 5 Transfer Means 6 Cleaning Means 7 Pre-Exposure Means 8 Image Fixing Means L Optical Image Exposure P Transfer Materials 10 Image Reading Parts 11 Controllers 12 Reception Circuits 13 Transmission circuit 14 Telephone 15 Line 16 Image memory 17 CPU 18 Printer controller 19 Printer

Claims (6)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support and a surface layer on the photosensitive layer, wherein the photosensitive layer comprises a charge generating substance, a charge transporting substance and a binder resin. In the electrophotographic photoreceptor, the surface layer of which contains fluorine atom-containing resin particles, a charge-transporting substance and a binder resin, wherein the constituent components of the binder resin of the surface layer and the binder of the photosensitive layer are contained. The constituent components of the resin are the same, and the binder resin contained in the surface layer is 50,000 to 160,
The number average molecular weight of the binder resin contained in the photosensitive layer is 10,000 to 50,000, and the number average molecular weight of the binder resin contained in the surface layer is An electrophotographic photosensitive member characterized by having a number average molecular weight of at least twice the binder resin contained in the photosensitive layer. 2. The number average molecular weight of the binder resin contained in the surface layer is 60,000 to 100,000, and the number average molecular weight of the binder resin contained in the photosensitive layer is 15,000 to 40,
The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is 000. 3. The electrophotographic photosensitive member according to claim 1, wherein the number average molecular weight of the binder resin contained in the surface layer is 6 times or less the number average molecular weight of the binder resin contained in the photosensitive layer. 4. The electrophotography according to claim 1, wherein the photosensitive layer has a charge generation layer and a charge transport layer, the charge generation layer is provided on the conductive support, and the charge transport layer is provided on the charge generation layer. Photoconductor. 5. The electrophotographic photosensitive member according to claim 1, comprising means for forming an electrostatic latent image, means for developing the formed electrostatic latent image, and means for transferring the developed image to a transfer material. An electrophotographic device characterized in that 6. The electrophotographic photosensitive member according to claim 1, and at least one unit selected from the group consisting of a charging unit, a developing unit and a cleaning unit are integrally supported,
The device unit is detachable from the device body.