JP3146635B2 - Electrophotographic photoreceptor and electrophotographic apparatus provided with the electrophotographic photoreceptor - 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 an electrophotographic apparatus having the electrophotographic photoreceptor. The present invention relates to an electrophotographic apparatus provided with an electrophotographic photosensitive member.

[0002]

2. Description of the Related Art Until now, most electrophotographic photoreceptors using an organic photoconductive substance have been prepared by dispersing a relatively low molecular weight charge generating substance such as an azo pigment or a phthalocyanine pigment in an appropriate binder resin. There are many. Among them, the 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. Because it ’s good,
At present, organic electrophotographic photosensitive members have become mainstream.

[0003] In a laminated photoreceptor, the carrier generation efficiency and carrier transport efficiency of the photosensitive layer, the carrier injection efficiency from the charge generation layer to the charge transport layer, and the like are important factors that determine the characteristics of the photoreceptor. The charge generation layer is basically composed of a charge generation substance and a binder resin.
It has a significant effect on potential characteristics and durability.

On the other hand, since the charge transporting material generally has a poor film-forming property, the charge transporting layer is used together with a binder resin to form a uniform film. Therefore, also in the charge transport layer, the characteristics of the binder resin have a significant effect on the carrier transport efficiency, the carrier injection efficiency, and the like, similarly to the charge generation layer. Further, in a laminated photoreceptor in which a charge transport layer is provided on the charge generation layer, the mechanical durability largely depends on the binder resin.

It is important to efficiently inject carriers generated in the charge generation layer into the charge transport layer for improving the sensitivity. If the combination of the charge generation layer and the charge transport layer is not good, not only high sensitivity cannot be achieved, but also adverse effects such as an increase in residual potential and memory, and an increase in environmental dependence and potential fluctuation are recognized.

Polycarbonate generally has good transparency,
It has been proposed as a binder resin for the charge transport layer because it has properties such as good compatibility with the charge transport material, high electrical insulation, high withstand voltage, good mechanical durability and good friction resistance. However, polycarbonate A represented by the following structural formula, which is a typical example of polycarbonate, has the following disadvantages.

Embedded image

(1) The resin has poor solubility and exhibits good solubility in solvents of halogenated aliphatic hydrocarbons such as dichloromethane and 1,2-dichloroethane, but these halogenated aliphatic hydrocarbons are Due to the low boiling point, when a photoreceptor is manufactured using a coating liquid prepared with these solvents, the coated surface is apt to whiten. (2) Although it is partially soluble in solvents other than halogenated aliphatic hydrocarbons in tetrahydrofuran, 1,4-dioxane, cyclohexanone and a mixed solvent thereof, the stability of the solution over time is poor and the photoreceptor Not suitable for the manufacture of (3) The adhesion of the coating film is poor, and cracks tend to occur from the interface. Therefore, polycarbonate A
It is difficult to obtain satisfactory characteristics by using as a binder resin for the charge transport layer.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a more sensitive electrophotographic photosensitive member by using a specific resin as a binder resin for a charge generation layer and a charge transport layer. To provide a stable electrophotographic photoreceptor, to provide an electrophotographic photoreceptor excellent in mechanical durability and excellent in productivity, and to provide an electrophotographic apparatus provided with the electrophotographic photoreceptor. It is.

[0009]

The present invention SUMMARY OF] is an electrophotographic photosensitive member comprising a laminate type photosensitive layer and at least a charge generation layer and a charge transport layer on a conductive support, said charge-generating layer is a compound represented by the following general formula ( containing polyvinyl acetal having the structure represented by 1), and consists of an electrophotographic photoreceptor, characterized in that said charge transport layer contains a polycarbonate represented by the following general formula (2). General formula (1)

Embedded image In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ represent a hydrogen atom, a fluorine atom or a trifluoromethyl group, and may be the same or different. However, at least R ₃ represents a fluorine atom or a trifluoromethyl group. General formula (2)

Embedded image In the formula, n represents 500 to 5,000, and R ₆ , R ₇ ,
R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ and R ₁₃ represent a hydrogen atom, a halogen atom or an alkyl group.

The polyvinyl acetal represented by the general formula (1) has a weight average molecular weight of 10,000 to 1,000,000.
00, especially 100,000 to 500,000.
Is preferably within the range. The degree of acetalization is preferably at least 50 mol%, particularly preferably 70 to 90 mol%. Further, the saponification degree of polyvinyl alcohol, which is a raw material of the polyvinyl acetal, is preferably 85% or more.

In the polycarbonate (polycarbonate Z) represented by the general formula (2), R ₆ , R ₇ , R
_{8, R 9, R 10,} R 11, R 12 and fluorine atom as the halogen atom indicated by R _13, a chlorine atom, a bromine atom. Examples of the alkyl group include a methyl group, an ethyl group.

[0012]

The typical examples of the polyvinyl acetal represented by the above general formula (1) are shown in Tables 1 and 2 for the acetal structure. However, it is not limited to the following exemplary resins.

[Table 1]

[Table 2]

Synthesis Example of Polyvinyl Acetal of Resin Example 1 60 ml of 1,2-dichloroethane was placed in a flask, and polyvinyl alcohol (polymerization degree: 1,000, saponification degree: 98.5%, Co., Ltd.) After adding 3.5 g of Kuraray Co., Ltd. and 20 g of p-fluorobenzaldehyde, concentrated hydrochloric acid was added.
6 ml was dropped, and the mixture was heated and stirred at 40 to 45 ° C. for about 8 hours. After the reaction, the reaction solution was added dropwise to a solution obtained by dissolving 0.3 g of sodium hydroxide in 2 liters of methanol. The precipitated resin was separated by filtration and 1,2-dichloroethane 1
The resin was dissolved in 00 ml and dropped into 2 liters of methanol again to precipitate the resin. The precipitated resin was separated by filtration and dried under reduced pressure to obtain 6.1 g of polyvinyl acetal of Resin Example 1 as a white flocculent resin. The degree of acetalization of this resin was measured according to the method described in Japanese Industrial Standards K6728 (Testing Method for Polyvinyl Butyral). As a result, the degree of acetalization was 81%.

Other polyvinyl acetals represented by the general formula (1) can be synthesized in the same manner as described above.

Table 3 shows typical examples of the polycarbonate Z represented by the general formula (2). However, it is not limited to the following exemplary resins.

[Table 3]

The polyvinyl acetal represented by the general formula (1) is preferably contained in the charge generation layer in an amount of 10 to 90% by weight, more preferably 20 to 50% by weight.

The polyvinyl acetal represented by the general formula (1) may be used as a binder resin for the charge generation layer together with another resin in such a ratio as not to impair the object of the present invention. Other resins include polyvinyl butyral, polyvinyl benzal, polyarylate, polycarbonate
Resin, such as polyester, phenoxy resin, acrylic resin, polyamide, polyurethane, polystyrene and acrylonitrile-styrene copolymer, or
Organic conductive polymers such as poly-N-vinyl carbazole and polyvinyl anthracene are exemplified.

Examples of the charge generating substance include azo pigments such as monoazo, disazo and trisazo, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, indigo pigments such as indigo and thioindigo, perylene anhydride, perylene imide and the like. Perylene pigments, polycyclic quinone pigments such as anthantrone and pyrenequinone, squarylium pigments, pyrylium, thiopyrylium salts, and triphenylmethane pigments.

The polycarbonate Z represented by the general formula (2) has good mechanical solubility of the polycarbonate, good solubility in various solvents, and a solution of the same. Is stable against aging, and greatly contributes to productivity improvement and quality stabilization. The polycarbonate Z may be used as a binder resin for the charge transporting layer together with another resin in such a ratio as not to impair the object of the present invention. Other resins include polyvinyl butyral, polyvinyl benzal, polyarylate, polycarbonate,
Resins such as polyester, phenoxy resin, acrylic resin, polyamide, polyurethane, polystyrene, and acrylonitrile-styrene copolymer; and organic conductive polymers such as poly-N-vinyl carbazole and polyvinyl anthracene.

The charge transporting material includes an electron transporting material and a hole transporting material. Examples of the electron transporting material include 2,4,7-
There are electron accepting substances such as trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, chloranil, and tetracyanoquinodimethane, and those obtained by polymerizing these electron accepting substances.

Examples of the hole transport material include polycyclic aromatic compounds such as pyrene and anthracene, carbazole, and indo-
, Imidazole, oxazole, thiazole, oxadiazol, pyrazol, pyrazoline, thiadiazo-
And heterocyclic compounds such as p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, N, N-diphenylhydrazino-3-methylden-
Hydrazone compounds such as 9-ethylcarbazole, α
-Styryl compounds such as -phenyl-4'-N, N-diphenylaminostilbene, 5- [4- (di-p-tolylamino) benzylidene] -5H-dibenzo [a, d] dichloroheptene, benzidine compounds, and triaryl-
Methane compounds, triphenylamine or polymers having a group consisting of these compounds in the main chain or side chain
(For example, poly-N-vinyl carbazole, polyvinyl anthracene, etc.).

As the solvent, tetrahydrofuran, 1,4
-Ethers such as dioxane, ketones such as cyclohexanone and methyl ethyl ketone, esters such as ethyl acetate and butyl acetate, aromatics such as toluene, xylene and monochlorobenzene, alcohols such as methanol and ethanol. And aliphatic halogenated hydrocarbons such as chloroform and methylene chloride; and amides such as N, N-dimethylformamide.

The charge generation layer is formed by dissolving a charge generation substance together with the above-mentioned specific resin in a solvent, and applying the obtained coating solution for a charge generation layer to a thickness of 5 μm or less.
In particular, 0.01 to 1 μm is preferable. 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 the carriers in the presence of an electric field. The charge transporting layer is formed by dissolving a charge transporting substance in a solvent together with the above-mentioned specific resin, and applying the solution.

As the conductive support, for example, aluminum, aluminum alloy, copper, zinc, stainless steel, titanium, nickel, indium, gold and platinum are used. Also, plastics (for example, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, etc.) and conductive particles (for example, car-
And a support in which conductive particles are impregnated in plastic or paper, and the like.

An undercoat layer having a barrier function and an adhesive function can be provided between the conductive layer and the photosensitive layer. Subbing layer is casein, polyvinyl alcohol, nitrocellulose
, Polyamide (nylon 6, nylon 66, nylon 610, copolymer nylon, alkoxymethylated nylon, etc.), polyurethane, aluminum oxide and the like. The film thickness is 5 μm or less, particularly 0.1 to 3 μm
Is preferred.

Further, 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 are applied by, for example, immersion coating, spray coating, spinner coating, bead coating, blade coating, beam coating, or the like. -Any coating method such as a tinging method can be used.

The reason why the electrophotographic photoreceptor of the present invention exhibits high sensitivity is that the energy barrier between the charge generation layer and the charge transport layer is small, which is advantageous in terms of carrier injection, and that the carrier inside the charge transport layer is high. This is because the mobility is large.

The electrophotographic photosensitive member of the present invention is 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 and facsimile.

Further, the present invention comprises an electrophotographic apparatus provided with the electrophotographic photoreceptor of the present invention.

[0030]

Next, an electrophotographic apparatus provided with the electrophotographic photosensitive member of the present invention will be described. FIG. 1 shows a schematic configuration of a general transfer type electrophotographic apparatus using the drum type photoreceptor 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 of 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 a developing unit 4, and the developed toner image is transferred by a transfer unit 5 between a photosensitive unit 1 and a transfer unit 5 from a paper supply unit (not shown) in synchronization with the rotation of the photosensitive unit 1. It is sequentially transferred onto the surface of the transfer material P taken and fed. The transfer material P having undergone the image transfer is separated from the photoreceptor surface, introduced into the image fixing means 8 and subjected to image fixing, and is printed out as a copy (copy) outside the machine. The surface of the photoreceptor 1 after the image transfer is cleaned and cleaned by removing the untransferred toner by the cleaning unit 6, subjected to a charge removal process by the pre-exposure unit 7, and used repeatedly for image formation. As the uniform charging means 2 for the photoreceptor 1, a corona charging device is generally widely used. Also, the corona transfer means is generally widely used for the transfer device 5. 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. You may.
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 a guide means such as a rail of the apparatus body. At this time, the above-described device unit may be provided with a charging unit and / or a developing unit. The light image exposure L
When an electrophotographic apparatus is used as a copier or a printer, the reflected light or transmitted light from the original is used, or the original is read and a laser beam is scanned and the light emitting diode array is driven by this signal. Or by driving a liquid crystal shutter array.

[0032]

[0033]

【Example】

Example 1 An aluminum cylinder of φ30 mm × 346 mm was prepared as a conductive support. Next, 10 g of alcohol-soluble copolymerized nylon (number average molecular weight 29,000) and methoxymethylated nylon (number average molecular weight 32,000)
5 g was dissolved in 95 g of methanol, and the coating solution was dip-coated on the aluminum cylinder to form an undercoat layer of 0.5 μm.

Next, 10 parts of a disazo pigment having the following structural formula:

Embedded image Resin Example 1 polyvinyl acetal (number average molecular weight 60,
000) and 120 parts of cyclohexane were dispersed in a sand mill for 20 hours. This dispersion was diluted with methyl ethyl ketone to prepare a coating liquid for the charge generation layer. This coating solution was applied on the undercoat layer to form a charge generation layer having a thickness of 0.2 μm.

Next, the polycarbonate Z of Resin Example 8 was replaced with 1
0 parts and 10 parts of a triarylamine compound of the following structural formula

Embedded image The coating solution was dissolved in 70 parts of monochlorobenzene, and this coating solution was applied on the charge generation layer to form a 20 μm charge transport layer.

The electrophotographic photoreceptor thus prepared was replaced by a Canon Inc.
The apparatus was mounted on a copying machine NP2020 and evaluated for electrophotographic characteristics. The rating is the dark potential of electrophotographic characteristics _{(V D)} -70
The potential (V _L ) when the exposure was set to 0 V and exposure of 1.0 lux · sec, and the potential change after repeated use 10,000 times were measured. Table 4 shows the results. The image sample after repeated use 10,000 times was also clear.

Examples 2 to 7 Example 1 was repeated except that the polyvinyl acetal of Resin Examples 2 to 7 was used as a binder resin of the charge generation layer, and Resin Examples 8 and 9 were used as the binder resin of the charge transport layer. The electrophotographic photosensitive members of Examples 2 to 7 were prepared in the same manner as in Example 1, and the electrophotographic characteristics were evaluated in the same manner as in Example 1. Table 4 shows the results.

[Table 4]

Comparative Example 1 Example 1 was repeated except that butyral resin (trade name: SREC BL-S, manufactured by Sekisui Chemical Co., Ltd.) was used in place of the polyvinyl acetal of Resin Example 1 of Example 1. An electrophotographic photoreceptor was prepared in the same manner as in Example 1, and the electrophotographic characteristics were evaluated in the same manner as in Example 1. Table 5 shows the results.

[Table 5]

Comparative Example 2 Polycarbonate A (trade name Panlite L-1250, manufactured by Teijin Chemicals Ltd.) was used in place of polycarbonate Z when forming the charge transport layer, and dioxane was used as a solvent.
An electrophotographic photosensitive member was prepared in the same manner as in Example 1, and the electrophotographic characteristics were evaluated in the same manner as in Example 1. Table 5 shows the results. Although the electrophotographic characteristics were not largely different from those of Example 1, the solution for coating the charge transport layer using the polycarbonate A had a solution viscosity increased by a factor of 3 to 4 after 24 hours, and when left for a longer period of time, the gel was gelled. And lost liquidity. On the other hand, the solution for coating the charge transport layer using polycarbonate Z was stable even after three months, and a large difference was observed between the two in the stability of the solution. Significant superiority was also observed in the preparation of electrophotographic photoreceptors.

Comparative Examples 3 to 5 In the same manner as in Example 1 except that the following resin was used in place of the polycarbonate Z when forming the charge transporting layer of Example 1, the electron transport of Comparative Examples 3 to 5 was performed. A photoreceptor was prepared. Comparative Example 3: Acrylic-styrene copolymer (trade name: Estyrene-200, manufactured by Nippon Steel Corporation) Comparative Example 4: Polystyrene (trade name: Stylon 470, manufactured by Asahi Kasei Corporation) Comparative Example 5: Polyester (trade name) Byron 200, manufactured by Toyobo Co., Ltd.)

The prepared electrophotographic photoreceptors of Comparative Examples 3 to 5 were placed in a copying machine having the same process as in Example 1, and a durability test was conducted. Had many scars. In addition, the potential characteristics deteriorated due to the abrasion of the photoreceptor surface before and after the endurance of 3,000 times, and fog occurred in the image sample.

[0042]

The electrophotographic photoreceptor of the present invention has a remarkable effect that it has excellent properties not only in initial characteristics but also in durability, and the electrophotographic photoreceptor according to the present invention also has a remarkable effect. The above-mentioned remarkable effects are exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a general transfer type electrophotographic apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Drum type photoreceptor as an image carrier (electrophotographic photoreceptor of the present invention) 1a shaft 2 Corona charging device 3 Exposure section 4 Developing means 5 Transfer means 6 Cleaning means 7 Pre-exposure means 8 Image fixing means L Transfer material after image transfer

 ──────────────────────────────────────────────────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 (56) References JP-A-62-10651 (JP, A) JP-A-2-256057 (JP, A) JP-A-4-27957 (JP, A) JP-A-3-45960 (JP, A) A) JP-A-1-239562 (JP, A) JP-A-3-23462 (JP, A)

Claims (4)

(57) [Claims] 1. A electrophotographic photosensitive member having a lamination type photosensitive layer with at least a charge generation layer and a charge transport layer on a conductive support, said charge generation layer has a structure represented by the following general formula (1) containing polyvinyl acetal, and an electrophotographic photosensitive member, characterized in that said conductive <br/> charge transport layer contains a polycarbonate represented by the following general formula (2). General formula (1) In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ represent a hydrogen atom, a fluorine atom or a trifluoromethyl group, and may be the same or different. However, at least
R ₃ represents a fluorine atom or a trifluoromethyl group
You . General formula (2) In the formula, n represents 500 to 5,000, and R ₆ , R ₇ ,
R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ and R ₁₃ represent a hydrogen atom, a halogen atom or an alkyl group. Wherein R _1, R _2, R ₄ and R ₅ indicates a hydrogen atom or a trifluoromethyl group, _{R 3} is trifluoromethanesulfonyl
The electrophotographic photoreceptor of claim 1, wherein shows the methyl group. 3. R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂
And R ₁₃ represents a hydrogen atom or a fluorine atom.
Or the electrophotographic photosensitive member according to 2. 4. The electrophotographic apparatus comprising the electrophotographic photosensitive member according to any one of claims 1 to 3.