JP3227190B2 - Electrophotographic photoreceptor, electrophotographic apparatus and apparatus unit using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photosensitive member having a photosensitive layer containing a resin having a specific structure, an electrophotographic apparatus and a device unit employing the same.

[0002]

2. Description of the Related Art In recent years, many electrophotographic photoreceptors using an organic photoconductive substance use a relatively low molecular weight charge generating substance such as an azo pigment or a phthalocyanine pigment dispersed in an appropriate binder resin. Often. Among them, a so-called laminated electrophotographic photosensitive member in which a photosensitive layer is functionally separated into a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance has sensitivity, potential characteristics and durability. Because of its superiority, it is currently the mainstream of organic electrophotographic photoreceptors.

In such an electrophotographic photosensitive member, the carrier generation efficiency and carrier transport efficiency of the photosensitive layer, and in the case of a stacked type, the efficiency of carrier injection from the charge generation layer to the charge transport layer, etc., determine the characteristics of the photosensitive member. Factors. These factors are considered to be affected not only by the properties of the charge generating substance and the charge transporting substance, but also by the properties of the binder resin. The mechanical strength and solvent resistance have been relatively emphasized and studied. JP-A-62-30254 describes that the structure, functional group or molecular weight of a binder resin affects the electrophotographic properties such as sensitivity, potential stability and residual potential of a photoreceptor, The binder resin is recognized as a functional resin.

However, with the recent demand for higher image quality and higher durability, electrophotographic photosensitive members having more excellent electrophotographic characteristics have been studied.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photoreceptor having high sensitivity and excellent electrophotographic characteristics having stable potential characteristics and excellent residual potential characteristics even when repeatedly used.

Another object of the present invention is to provide an electrophotographic apparatus and an apparatus unit having the above-described electrophotographic photosensitive member.

[0007]

That is, the present invention relates to an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer has the following formula [I]:

[0008]

[Outside 2] Wherein R ₃ is a fluorine atom or a trifluoromethyl group
In _{and, R 1, R 2, R} 4 and R ₅ are the same or different and each represents a hydrogen atom, indicates a fluorine atom and trifluoromethyl group
You. An electrophotographic photosensitive member comprising a resin having a structure represented by the formula (1).

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

The weight average molecular weight of the polyvinyl acetal resin having a structure represented by the formula [I] used in the present invention is preferably from 10,000 to 1,000,000, and particularly preferably from 100,000 to 500,000. 000 is preferred. The degree of acetalization is preferably 50 mol% or more, and particularly preferably 70 to 90 mol%. Further, the degree of saponification of polyvinyl alcohol used as a raw material of the polyvinyl acetal resin is preferably 85% or more.

In the present invention, by using a polyvinyl acetal resin having a structure represented by the formula [I] for the photosensitive layer, remarkable improvement in sensitivity, potential stability upon repeated use and reduction in residual potential are recognized. . this is,
This is considered to be due to an improvement in carrier generation efficiency due to an electronic interaction between the charge generation substance and the above-mentioned polyvinyl acetal resin having a fluorine atom or a trifluoromethyl group as an electron-accepting substituent.

In other words, the polyvinyl acetal resin used in the present invention also acts as a kind of electron accepting substance, so that the dissociation efficiency of the carrier is promoted by the electronic interaction with the organic compound as the charge generating substance, and the recombination of the carrier. It is considered that the suppression of is effective in generating free carriers. In particular, it is considered that a fluorine atom and a trifluoromethyl group have a very high electronegativity, and the above-mentioned effects appear very remarkably.

In the following, typical examples of the polyvinyl acetal resin used in the present invention will be illustrated with respect to the acetal structure portion, but of course the present invention is not limited thereto.

[0014]

[Table 1]

[0015]

Of these, R ₁ , R ₂ , R ₄ and R ₅ are preferably hydrogen.

Next, a synthesis example of the polyvinyl acetal resin used in the present invention will be described.

(Synthesis Example) 60 ml of 1,2-dichloroethane was placed in a flask, and polyvinyl alcohol (polymerization degree: 1000, saponification degree: 98.5%, manufactured by Kuraray Co., Ltd.)
After adding 5 g and 20 g of p-fluorobenzaldehyde, 0.6 ml of concentrated hydrochloric acid was added dropwise, and the mixture was heated and stirred at a temperature of 40 to 45 ° C. for about 8 hours. After the reaction, sodium hydroxide 0.3
The reaction solution was added dropwise to a solution of g in 2 l of methanol. The precipitated resin is separated by filtration and 1,2-dichloroethane 1
The resin was dissolved in 00 ml and dropped into 2 l of methanol again to precipitate the resin. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white flocculent resin, such as Ex. 6.1 g of the polyvinyl acetal resin No. 1 was obtained. When the degree of acetalization of this resin was measured according to the method described in Japanese Industrial Standards K6728 (polyvinyl butyral test method), the degree of acetalization was 81%.

Other polyvinyl acetal resins used in the present invention can be synthesized in the same manner as described above.

In the present invention, the photosensitive layer can be a charge-generating layer containing a charge-generating substance and a charge-transporting layer containing a charge-transporting substance. It may be a single-layer type, but is preferably a laminated type photosensitive layer.

In the case of a laminate type, the polyvinyl acetal resin used in the present invention is preferably contained at least in the charge generation layer.

[0022] The content of the polyvinyl acetal resin used in the present invention is 1 to the layer containing the resin.
It is preferably 0 to 90% by weight, particularly preferably 20 to 90% by weight.
Preferably it is 50% by weight.

The polyvinyl acetal resin used in the present invention may be used together with another resin. Other resins include resins such as polyvinyl butyral, polyvinyl benzal, polyarylate, polycarbonate, polyester, phenoxy resin, acrylic resin, polyacrylamide, polyamide, polyurethane, polystyrene and acrylonitrile-styrene copolymer, or poly-N-vinyl carbazole And an organic photoconductive polymer such as polyvinyl anthracene. Further, in the present invention, a copolymer of the component represented by the formula [I] and the above-mentioned resin component can also be used.

Examples of the charge generating substance used in the present invention include azo pigments such as monoazo, bisazo and trisazo, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, indigo pigments such as indigo and thioindigo, and perylene anhydride. Products, perylene pigments such as perylene imide, polycyclic quinone pigments such as anthrone and pyrenequinone, squarium pigments, pyrylium, thiopyrylium salts, and triphenylmethane pigments.

The charge transporting substance includes an electron transporting substance and a hole transporting substance.
There are electron accepting substances such as 4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, chloranil, and tetracyanoquinodimethane, and polymers obtained by polymerizing these electron accepting substances.

Examples of the hole transport material include polycyclic aromatic compounds such as pyrene and anthracene; carbazole, indole, imidazole, oxazole, thiazole, oxadiazole, oxazole, thiazole, oxadiazole, pyrazole, pyrazoline, thiadiazole, and triazole. Heterocyclic compounds such as p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, N, N
Hydrazone compounds such as -diphenylhydrazino-3-methylidene-9-ethylarbazole; α-phenyl-4'-N, N-diphenylaminostilbene;
[4- (di-p-tolylamino) benzylidene] -5H
Styryl compounds such as -dibenzo [a, d] dicloheptene; benzidine compounds; triarylmethane compounds; triphenylamine or polymers having a group consisting of these compounds in the main chain or side chain (for example, poly-N- Vinylcarbazole, polyvinylanthracene, etc.).

The charge generation layer can be formed by applying a solution in which the above-described charge generation substance is dispersed in the above resin using an appropriate solvent on a conductive support and drying the solution. The thickness is preferably 5 μm or less, particularly preferably 0.01 to 1 μm.

The charge transport layer is stacked on or below the charge generation layer, and has a function of receiving carriers from the charge generation layer and transporting them in the presence of an electric field. The charge transport layer is formed by dissolving the above-described charge transport material in a solvent together with an appropriate binder resin as necessary and coating and drying the film. The film thickness is preferably 5 to 40 μm, and particularly preferably 15 to 40 μm.
30 μm is preferred.

The single-layer type photosensitive layer can be formed by applying a solution obtained by dispersing and dissolving the above-mentioned charge generating substance and charge transporting substance in the above-mentioned resin using a solvent on a conductive support and drying the solution. The thickness is preferably 1 to 40 μm, and particularly preferably 10 to 30 μm.

Solvents used for forming these layers include ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as cyclohexanone and methyl ethyl ketone; esters such as ethyl acetate and butyl acetate; toluene and xylene. And aromatics such as monochlorobenzene, alcohols such as methanol and ethanol, aliphatic halogenated hydrocarbons such as chloroform and methylene chloride, and amides such as N, N-dimethylformamide.

As the conductive support used in the present invention, for example, aluminum, aluminum alloy, copper, zinc, stainless steel, titanium, nickel, indium, gold and platinum are used. A support obtained by coating such a metal or alloy on a plastic (eg, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, etc.) by vacuum evaporation, or a conductive particle (eg, carbon black, silver particle, etc.) with an appropriate binder A support coated on a plastic or metal substrate together with a resin, a support in which conductive particles are impregnated in plastic or paper, or the like can be used.

Examples of the shape of the support include a sheet shape, a drum shape, and a belt shape, and it is preferable that the shape is any shape suitable for the electrophotographic photosensitive member to be applied.

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, copolymer nylon, alkoxymethylated nylon, etc.), polyurethane, aluminum oxide, etc. The thickness is preferably 5 μm or less, particularly preferably 0.1 to 3 μm.

Further, in the present invention, a resin layer or a resin layer containing conductive particles can be laminated as a protective layer on the photosensitive layer.

The above-mentioned various layers can be applied by any coating method, for example, a dipping method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method and the like.

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 applications such as RT printers, LED printers, liquid crystal printers, and laser plate making.

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

In FIG. 1, reference numeral 1 denotes a drum-type photosensitive member 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 operation exposure etc.). 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 a developing unit 4, and the developed toner image is transferred by a transfer unit 5 between the photosensitive member 1 and a transfer unit 5 from a paper feeding unit (not shown). Are sequentially transferred onto the surface of the transfer material P fed in synchronization with the transfer.

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.

The surface of the photoreceptor 1 after the image transfer is cleaned and cleaned by removing the untransferred toner by the cleaning means 6, and further subjected to a charge removal treatment by the pre-exposure means 7, and is repeatedly used for image formation.

As the uniform charging means 2 for the photosensitive member 1, a corona charging device is generally widely used. Transfer device 5
Also, corona transfer means are generally widely used. 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, a unit is formed by integrally supporting at least one of the charging unit, the developing unit, and the cleaning unit together with the photoreceptor, and the unit is detachably attached to the apparatus main body. It may be configured to be detachable. At this time, the above-described device unit may be provided with a charging unit and / or a developing unit.

When the electrophotographic apparatus is used as a copying machine or a printer, the light image exposure L involves irradiating the photosensitive member with reflected light or transmitted light from the original, or reading the original with a sensor and converting it into a signal. According to this signal, scanning of a laser beam, driving of an LED array, or driving of a liquid crystal shutter array is performed to irradiate light to a photoconductor.

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 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.

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 performs a composite processing of the image information and sequentially stores the image information in the image memory 16. Is stored. Then, when the image of at least one page is stored in the memory 16,
The image of the page is recorded. The CPU 17 is a memory 1
6, one page of image information is read out and the combined one-page image information is sent to the printer controller 18. The printer controller 18 receives 1
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 receives the next page during recording by the printer 19.

As described above, image reception and recording are performed.

Hereinafter, the present invention will be described in more detail by way of examples.

[0051]

【Example】

1. On an aluminum plate support, 5 g of a methoxymethylated nylon resin (number average molecular weight 32,000) and an alcohol-soluble copolymerized nylon resin (number average molecular weight 29,00
0) A solution in which 10 g was dissolved in 95 g of methanol was applied by a Meyer bar, and an undercoat layer having a thickness of 1 μm after drying was provided.

Next, a bisazo pigment having the following structure

[0053]

[Outside 3] 5 g is added to 90 g of cyclohexanone, and 2
Dispersed for 0 hours. Further, this liquid was added with the exemplified resin No. 1 polyvinyl acetal resin (weight average molecular weight 160,00
0) A solution in which 2 g was dissolved in 20 g of cyclohexanone was added, and the mixture was further dispersed for 2 hours.

200 g of methyl ethyl ketone was added to the dispersion.
Was added and diluted, and a film thickness of 0.1 was formed on the undercoat layer formed earlier.
The resultant was coated with a Meyer bar so as to have a thickness of 2 μm, and dried to form a charge generation layer.

Then, the following equation

[0056]

[Outside 4] Is dissolved in 40 g of monochlorobenzene, and this is coated on a charge generation layer with a Meyer bar, and dried to form a 20 μm charge transport layer. By forming, an electrophotographic photoreceptor was obtained.

The thus prepared electrophotographic photosensitive member is negatively charged by a corona discharge of -5 KV using an electrostatic copying machine tester (Model SP-428, manufactured by Kawaguchi Electric Co., Ltd.), and is darkened for 1 second. After being left at the place, the charging characteristics were evaluated by exposing to light having an illuminance of 10 lux using a halogen lamp. As the charging characteristics, a surface potential V ₀ , an exposure amount (that is, sensitivity) E _1/2 and a residual potential Vr required to attenuate the surface potential after leaving in a dark place for 1 second to １ ／ were measured. As a result, V ₀ is −700 V and E _1/2 is 1.2 lu
At x · sec, Vr was 0V.

2. Instead of the bisazo pigment used in Example 1, the following structural formula

[0059]

[Outside 5] Is used as a binder resin for a charge generation layer. Except using 5 of poly (vinyl acetal) resin (weight average molecular weight 170,000) is to produce the electrophotographic photosensitive member in the same manner as in Example 1 to evaluate charging characteristics. As a result, V ₀ was −710 V, E _1/2 was 1.3 lux · sec, and Vr was 0 V.

3. Instead of the bisazo pigment used in Example 1, the following formula

[0061]

[Outside 6] Is used, tetrahydrofuran is used as a dispersing solvent, a 1: 1 mixed solvent of cyclohexanone and tetrahydrofuran is used as a diluting solvent, and the following formula is used instead of the styryl compound.

[0062]

[Outside 7] An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the triarylamine represented by the following formula was used. As a result, V ₀ is −705 V, and E _1/2 is 0.8 lux · se.
At c, Vr was 0V.

4. Instead of the charge-generating layer dispersion used in Example 1, 350 g of tetrahydrofuran was added to 10 g of metal-free phthalocyanine. 6
Of polyvinyl acetal resin (weight average molecular weight 170,
000) was added to 50 g of tetrahydrofuran, and an electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that a dispersion liquid dispersed by a sand mill for 10 hours was used, and the charging characteristics were evaluated. As a result, V ₀ is −670 V
Where E _1/2 is 1.8 lux · sec and Vr is −30 V
Met.

5. An electrophotographic photosensitive member was prepared in the same manner as in Example 4 except that copper phthalocyanine was used instead of the metal-free phthalocyanine used in Example 4, and the charging characteristics were evaluated. As a result, V ₀ is −680 V and E _1/2 is 5.6 l
In ux · sec, Vr was −35V.

(Comparative Examples 1, 2, 3 and 4) Instead of the polyvinyl acetal resin used in Example 1, the following structural formula

[0066]

[Outside 8] (Wherein, X represents a hydrogen atom, a nitro group, a methyl group and a chlorine atom.) In the same manner as in Example 1 except that a polyvinyl acetal resin having a structure represented by the following formula (acetalization degree: 75 to 80%) was used. To prepare an electrophotographic photosensitive member, and the charging characteristics were evaluated. However, Vr was not measured. Table 1 shows the results.

[0067]

[Table 3]

Comparative Example 5 An electrophotographic photosensitive member was prepared in the same manner as in Example 4 except that the polyvinyl acetal resin used in Comparative Example 2 was used instead of the polyvinyl acetal resin used in Example 4, and the charging characteristics were evaluated. evaluated. As a result, V ₀ is −680 V and E _1/2
Was 2.3 lux · sec, and Vr was −80 V.

6. To 4 g of the bisazo pigment used in Example 1, 90 g of cyclohexanone was added and dispersed by a sand mill for 20 hours. To this dispersion, exemplified resin No. 1 polyvinyl acetal resin (weight average molecular weight 160,000) 2
A solution in which 0 g was dissolved in 300 g of tetrahydrofuran was added, and the mixture was shaken for 2 hours. Further, 40 g of the styryl compound used in Example 1 and Example Resin No. A solution obtained by dissolving 20 g of the polyvinyl acetal resin (weight average molecular weight: 160,000) in 200 g of tetrahydrofuran was added thereto, followed by shaking. The coating solution thus prepared was applied to an aluminum plate support with a Meyer bar, and dried to a film thickness of 20 μm.
To form an electrophotographic photoreceptor.

The charging characteristics of this electrophotographic photoreceptor were measured in Example 1.
Was evaluated in the same manner as described above. However, the charging is positive, and V
r was not measured. As a result, V ₀ is 710 V and E
_1/2 was 2.0 lux · sec.

7.8. And 9. The electrophotographic photoreceptor prepared in Examples 1 to 3 is a cylinder of an electrophotographic copying machine equipped with a corona charger of -6.5 kV, an exposure optical system, a developing device, a transfer charger, a charge eliminating exposure optical system, and a cleaning unit. Pasted on. Initial dark potential V _D and the light portion potential V _L respectively -700 V, set to be -200 V, 50
The variation amount ΔV _D of the dark area potential when repeatedly used 00 times
To evaluate the durability characteristics of the photoreceptor by measuring the variation amount [Delta] V _L of the light portion potential. Table 2 shows the results. Note that a negative value of the potential fluctuation indicates that the absolute value of the potential has decreased, and a positive value indicates that the absolute value of the potential has increased.

[0072]

[Table 4]

(Comparative Examples 6.7 and 8) Comparative Examples 1-4
The amount of potential fluctuation during repeated use was measured in the same manner as in Example 7 except that the electrophotographic photoreceptor prepared in the above was used. Table 3 shows the results.

[0074]

[Table 5]

10. A photoreceptor was prepared by laminating the charge generation layer and the charge transport layer of the electrophotographic photoreceptor prepared in Example 3 in reverse order, and the charging characteristics were evaluated in the same manner as in Example 1. However, the charging was positive, and Vr was not measured.
As a result, V ₀ is 700 V and E _1/2 is 1.5 lux · s.
ec.

11. The coating solution for the charge transport layer used in Example 1 was composed of 2,4,5-trinillo-9-fluorenone (5 g) and a polycarbonate resin (number average molecular weight 300,000).
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 5 g of the solution was dissolved in 50 g of tetrahydrofuran.
The charging characteristics were evaluated. However, the charging was positive, and Vr was not measured. As a result, V ₀ was 690 V and E _1/2 was 2.0 lux · sec.

[0077]

As described above, the electrophotographic photoreceptor of the present invention uses a specific polyvinyl acetal resin having a fluorine atom or a trifluoromethyl group as a binder resin for the photosensitive layer, thereby improving sensitivity and repetitive use. Characteristics with excellent potential stability can be obtained.

[Brief description of the drawings]

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

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

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Satomi Omura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (72) Inventor Masato Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-62-10651 (JP, A) JP-A-62-30254 (JP) , A)

Claims (4)

(57) [Claims] 1. An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer has the following formula [I]: Wherein R ₃ is a fluorine atom or a trifluoromethyl group
In _{and, R 1, R 2, R} 4 and R ₅ are the same or different and each represents a hydrogen atom, indicates a fluorine atom and trifluoromethyl group
You. An electrophotographic photosensitive member comprising a resin having a structure represented by the formula: Wherein said R _1, R _2, R ₄ and the electrophotographic photosensitive member according to claim 1, wherein R ₅ is a hydrogen atom. 3. An electrophotographic photosensitive member according to claim 1 or 2, an electrostatic latent image forming means, a means for developing the formed electrostatic latent image, and a means for transferring the developed image to a transfer material. An electrophotographic apparatus characterized by the following. 4. An electrophotographic photoreceptor according to claim 1, comprising a charging unit and a cleaning unit, wherein the electrophotographic photoreceptor, the charging unit and the cleaning unit are integrally supported, and are detachable from the apparatus main body. An apparatus unit, characterized in that: