JPH01164953A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an excellent sensitivity even to a short wave side wavelength region and to obviate accumulation of residual potential and deterioration of electrostatic chargeability by incorporating a specific azo pigment in an electric charge generating layer. CONSTITUTION:The azo pigment expressed by the formula I is used in the charge generating layer. In the formula I, A denotes the formula II, etc. In the formula II, X denotes an arm. ring such as benzene ring, naphthalene ring, a heterocycle such as indole ring, carbazole ring or benzofuran ring or the substitution products thereof; Ar1 denotes an arom. ring such as benzene ring, naphthalene ring or heterocycle such as dibenzofuran or the substitution products thereof; R1 denotes a hydrogen atom., lower alkyl group, etc. The electrophotographic sensitive body which exhibits the excellent sensitivity even to the short wave side wavelength region, obviates the accumulation of the residual potential and the deterioration of the electrostatic chargeability and has the excellent durability is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to an improvement in an electrophotographic photoreceptor having a layer in which a charge generating substance is dispersed.

[Prior Art] Electrophotographic photoreceptors have been known that are provided with a charge generation layer containing a charge generation substance and various resins.

Examples of this include polyvinyl butyral (Japanese Patent Application Laid-open No. 58-105154), fatty acid cellulose ester (
JP-A No. 58-166353), acrylic resin with Tg of 70°C or less and an acid value of 10 to 40 (JP-A No. 58-1920)
No. 40), a mixture of a resin with a Tq of 70°C or lower and a resin with a Tg of 75°C or higher (JP-A-58-193549@)
, Chinoku JP-A-56-1, in which a less compatible resin-solvent system is added to the charge-generating substance-resin-solvent system and redispersed.
No. 2646), polyvinylpyrrolidone (JP-A-56-1
13140) and polyvinyl formal resin (Japanese Unexamined Patent Publication No. 61-235844).

However, conventionally known photoreceptors have a problem in that sensitivity and chargeability against pre-exposure fatigue vary depending on the mixing ratio of the charge generating substance and the binder resin.

In other words, the sensitivity of conventional photoreceptors can be increased by reducing the time between use of the binder resin with respect to the charge-generating substance, but the charging performance deteriorates significantly due to pre-exposure fatigue, and conversely, the use of the binder resin with respect to the charge-generating substance is If the amount is increased, it is possible to suppress a decrease in chargeability due to pre-exposure fatigue, but this includes the problem that the sensitivity decreases considerably.

Furthermore, in recent years, organic photoreceptors, particularly negatively charged photoreceptors in which a charge generation layer and a charge transfer layer are successively laminated on a support, have been widely used. This photoreceptor generates more ozone than the positively charged type, and therefore the surface of the photoreceptor is susceptible to chemical changes, resulting in blurred images and increased residual potential.

In addition, light yellow to light yellow compounds such as hydrazone compounds, pyrazoline compounds, oxazole compounds, and styryl compounds are used in the charge transfer layer.
Since a yellow hole transfer material is used, short wavelength light, such as blue light of 500 nm or less, is absorbed by this charge transfer layer, and such a photoreceptor has the disadvantage of extremely weak sensitivity in the short wavelength range. . This decrease in sensitivity is significant for blue light, and therefore the light attenuation effect cannot be achieved unless the amount of light is increased. However, increasing the amount of light in this manner causes a problem in that fatigue accumulates on the photoreceptor and its durability decreases.

On the other hand, in a positively charged photoreceptor in which a charge transfer layer and a charge generation layer are laminated in that order, the charge generation layer becomes the surface layer, and the surface layer wears out due to repeated processes of charging, exposure, development, transfer, and cleaning. and its durability decreases.

As a method to eliminate these drawbacks, a method of increasing the thickness of the charge generation layer has been proposed (Japanese Patent Laid-Open No. 59-22
4846, JP-A-59-174849), this method has the disadvantage that residual potential accumulates due to carrier traps in the charge generation layer and charging properties deteriorate.

[Objective] It is an object of the present invention to provide an electrophotographic photoreceptor that exhibits excellent sensitivity even in the short wavelength range, does not accumulate residual potential or deteriorate chargeability, and has excellent durability. purpose.

[Structure] According to the present invention, in an electrophotographic photoreceptor in which a charge transfer layer, a charge generation layer, an intermediate layer, and a protective layer are sequentially provided on a conductive support, the charge generation layer contains an azozoic acid compound represented by the following general formula. An electrophotographic photoreceptor characterized by using a pigment is provided.

゛・8 PA″ “′ 0CH3 (Here, Aromatic rings such as naphthalene rings, heterocycles such as dibenzofuran, or substituted products thereof, Ar2 and Ar3 are aromatic rings such as benzene rings and naphthalene rings, or substituted products thereof, R1 and R3 are hydrogen atoms, lower alkyl groups, phenyl R2 represents a lower alkyl group, a carboxyl group, or an ester thereof. ] Next, each constituent material used in the present invention will be explained.

The conductive support is intended to supply charges of opposite polarity to the charged charges to the substrate side, and has an electrical resistance of 1.
08 Ωcm or less and can withstand the film forming conditions of the undercoat layer for the charge generation layer and the charge transfer material. Examples of these are AI, Ni, Cr, Z
n, electrically conductive metals and alloys such as stainless steel, inorganic insulating materials such as glass and ceramics, and polyester, polyimide, phenolic resin, nylon resin,
The surface of organic insulating materials such as paper is coated with AI, Ni, Cr,
Examples include those coated with an electrically conductive substance such as Zn, stainless steel, carbon, SnO, In2O3, etc. and subjected to conductive treatment.

The charge transfer layer can be formed by dissolving or dispersing a charge transfer substance and a resin binder in a suitable solvent, coating the solution on a conductive substrate, and drying the solution. Furthermore, a plasticizer, a leveling agent, etc. can be added if necessary.

Charge transfer substances include poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives, and imidazole. M4 form, triphenylamine derivative, 9-(p-diedylaminostyryl)anthracene, 1,1-bis-(4-dibenzylaminophenyl)propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenyl Examples include electron-donating substances such as stilbene derivatives.

Examples of the resin binder include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and polystyrene used in the charge generation layer. Polymer, polyvinyl acetate, polyvinylidene chloride, polyacrylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal,
polyvinyltoluene, poly-N-vinylcarbazole,
Examples include thermoplastic or thermosetting resins such as acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.

As the solvent at this time, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, styrene chloride, etc. can be used.

The thickness of the charge transport layer is 5 to 40 μm, preferably 10 to 40 μm.
Approximately 25 μm is appropriate.

The charge generation layer of the present invention contains an azo pigment represented by the following general formula (I>).

0CH3 (here, X is an aromatic ring such as a benzene ring or a naphthalene ring,
Heterocycles such as indole rings, carbazole rings, benzofuran rings or substituted products thereof; Ar+ is aromatic rings such as benzene rings and naphthalene rings; heterocycles such as dibenzofuran or substituted products thereof; Arz and Ar3 are benzene rings , aromatic@rings such as naphthalene rings or substituted products thereof, R
1 and R3 represent a hydrogen atom, a lower alkyl group, a phenyl group, or a substituted product thereof, and R2 represents a lower alkyl group, a carboxyl group, or an ester thereof. ] Specific examples of the compounds of the general formula used in the present invention are shown below in terms of structural formulas.

−＋N lie
. Φ
NC%J
F5 size
Dimensions of 111~
jN N N
〜ΦN
ωN N
He■ 0 M”
M's
e+>35-d
6-V
Dimension -N +1' lie Dimension on the verge
size ω
[F] Rope
@1?
φ of C
”-FJψ
Nono +e
punishment ωω
Φ 1.0
The Φ charge generation layer is prepared by adding the azo pigment to a suitable solvent, pulverizing and dispersing it using a method such as a ball mill, an attritor, or a motion mill, and applying the resulting dispersion onto the charge generation layer and drying it. It can be formed by

Examples of solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohequilinone, amides such as dimethylformamide and dimethyl sulfamide, tetrahydrofuran, dioxane,
Ethers such as ethylene glycol monoalkyl ether and ethylene glycol dialkyl ether, esters such as methyl acetate, ethyl acetate, and butyl acetate, aliphatic halogenated hydrocarbons such as methylene chloride and dichloroethane, aromatics such as benzene, toluene, and xylene. Examples of the hydrocarbons include group hydrocarbons, halogenated aromatic hydrocarbons such as monochlorobenzene, and these may be used alone or as a mixture of two or more.

Application methods include dip coating, spray coating, spinner coating, bead coating, wire bar coating, blade coating, roller coating, curtain coating, and screen printing. Conventionally known methods can be mentioned. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying can be carried out at a temperature of 30 to 200° C. for a period of from 5 minutes to 2 hours, either stationary or under ventilation.

In the present invention, the charge generation layer may contain a binder resin, but it is desirable not to contain it if possible. This is because the presence of the binder resin inhibits the mobility of generated charge carriers and also causes an increase in residual potential.

The thickness of the charge generation layer is O,OS~2μm, preferably 0.1μm.
~1 μm.

In the present invention, an intermediate layer is provided on the charge generation layer as a layer for preventing charge injection due to corona charging.

Since the resin used for the intermediate layer is provided on the fine particle thin layer of the charge generation layer, if it has good compatibility with the charge transfer layer resin and the charge generation layer binder resin, it will penetrate into the layer and the interface will become unclear. As a result, the injection of surface charges becomes severe, so it is necessary to select a resin for the intermediate layer that has poor compatibility with the layer.

Therefore, it is necessary that the solubility parameter with the layer-forming resin reaches 0.2 or more. These resins include polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, polyacrylic acid, polyhydroxyalkyl methacrylate, polyhydroxyalkyl acrylate, polyvinyl alcohol, polyamide, cellulose derivatives, phenolic resin, polyethylene oxide, polyethylene glycol, polyvinyl ether, etc. It is dissolved in an alcohol-based, cellosolve-based, ketone, ester, nityl, or aromatic solvent or mixed solvent and coated on the charge generation layer with a film thickness of o, oi to 5 μm, preferably 0.05 to 1 μm.
Coat with m.

Further, in the present invention, it is necessary to provide a protective layer on the intermediate layer in order to improve wear resistance, damage resistance, etc.

Protective layer resins include ABS resin, AC3 resin, olefin vinyl copolymer resin, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide,
Polyamideimide, polyarylate, polyallylsulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene,
Examples include polyethylene terephthalate, polyimide, methacrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polybrene, AS resin, butadiene-styrene resin, polyurethane, polyvinyl chloride, polyvinylidene chloride, and epoxy resin.

In addition, from the viewpoint of wear resistance, polytetrafluoroethylene resin, fluorine resin, and silicone resin can be added as additives to lower the friction coefficient and improve wear resistance and scratch resistance. Abrasion resistance can also be improved by dispersing inorganic compounds such as tin oxide and potassium titanate in the resin. The thickness of this surface protective layer is 0.5 to 10 μm,
Preferably it is 1 to 5 μm.

[Effect] Since the electrophotographic photoreceptor of the present invention has the above configuration,
It exhibits excellent sensitivity even in the short wavelength range, and has excellent durability without accumulation of residual potential or deterioration of charging performance.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that both parts and percentages are based on weight.

Example 1 The following solution was prepared in an 80φ340 stroke aluminum cylinder, coated by dipping, and dried at 120° C. for 20 minutes to form a charge transfer layer of 20 μm.

Polycarbonate resin 340Q (C-
140Q Teijin) Dichloromethane 32()OCJ
Silicone oil (KF-50 manufactured by Shin-Etsu Chemical Co., Ltd.) 0.
Next, the following charge generation layer forming solution was prepared and applied by spraying, and dried at 120° C. for 20 minutes to form a charge generation layer of 0.4 μm.

No. 1 disazo pigment...
...30g polyvinyl butyral (XYIILU
(manufactured by CC)...30(]cyclohexanone
......400Q was ground and dispersed in a ball mill for 48 hours, and cyclohexanone/MEK = 1/1.
A weight ratio of 500q was added and after dispersion for 2 hours, a coating liquid was prepared.

Next, the following solution was prepared and applied by spraying at 120°C.
, and dried for 10 minutes to provide a 0.4 μm intermediate layer.

Polyamide (CM-8000 manufactured by Toshisha) ・・・・・・
・・・1g methanol ・・・・・・
・・・7q Butanol ・・・
...2g Next, the following dispersion was prepared, coated by a spray method, and dried at 120°C for 20 minutes to form a 4 μm protective layer.

Styrene: Methyl methacrylate: 2-hydroxyethyl methacrylate = 3:5:2 (weighted) copolymer
・・・・・・・・・4qsno
x <Made by Sumitomo Cement) ・・・・・・・・・6q
Toluene ・・・・・・・・・
30g MEK・・・・・・
...5qn-butanol ...
...5q was ground and dispersed in a ball mill for 72 hours, and red-downed to a solid content of 2% with cellosolve acetate. This contains an isocyanate compound (Sumidur 1 (
T1 Sumitomo Bayer Urethane) 3q was added to prepare a coating liquid.

This photoreceptor was rotated at 11,000 rpm in a dark place +
5 was applied with a voltage of V and charged for 20 seconds. The value at that time was taken as vm, and the potential after 20 seconds of discharge was taken as VO, and the dark decay rate VO/Vllll was determined. After that, 2
6Lux tungsten light with slit width 611II11
It was irradiated from E1/2 (Lu
x・sec) Also, the exposure amount reduced to 1/10 is E 1 /
10 (LUX-SeC). The potential 30 seconds after the start of exposure was defined as VR.

The durability test was carried out using a Ricoh FT-5510, and the quenching lamp was equipped with a filter that cuts light of 460 nm or less. Charging is dark area potential 800V, light area potential 8
The charger and lamp light intensity were adjusted to 0V. The results are shown in Table 1 below.

Examples 2 to 10 Photoreceptors were prepared in accordance with the photoreceptor manufacturing method of Example 1, except that disazo pigments with the numbers shown in 1 below were used in place of the disazo pigments No. 1 and 1 in Example 1, respectively. The same measurements as in Example 1 were carried out on the photoconductor of
The result was 1q.

Comparative Example 1 A charge transfer layer, a charge generation layer, and an intermediate layer were provided in the same manner as in Example 1. Further, no protective layer was provided. The results are shown in Table-2.

Comparative Example 2 A charge transfer layer and a charge generation layer were provided in the same manner as in Example 1, but a protective layer was provided without providing an intermediate layer. The results are shown in Table-2.

Example 11 250 parts of polycarbonate (C-1400 made by Kandai) 2 were placed in an aluminum cylinder with an outer diameter of 80φ and a length of 340111 m.
80 parts, silicone oil (manufactured by Shin-Etsu Chemical, F-50)
0.5 part was dissolved in 1700 parts of tetrahydrofuran.

This solution was coated on the charge generation layer by a dipping method and heated to 120°C.
After drying for 30 minutes, a charge transfer layer with a thickness of 20 μm was provided.

The charge generation layer forming liquid used in Example 1 was applied onto the charge transfer layer by a spray method to form a charge generation layer having a thickness of 0.4 μm. After a rough layer of 0.2 μm of ethyl cellulose was provided on the charge generation layer, the following protective layer was provided with a thickness of 4 μm.

Polyurethane (273H, manufactured by Nippon Polyurethane Co., Ltd.) (s
, p value 10. O) ・・・・・・・・・
4qSnOX (manufactured by Sumitomo Cement Co., Ltd.) ・・・・・・
...6q cyclohexanone ...
...100 (J was ground and dispersed in a ball mill for 72 hours,
The coating solution was prepared by letting down with TI-(F). The results are shown in Table 3.

Examples 12 to 15 Photoreceptors were produced in the same manner as in Example 11 using the disazo pigments shown in Table 3 below. The results are shown in Table-3.

As described above, the photoreceptor of the present invention provides a highly durable and highly sensitive photoreceptor with little variation in electrical properties.

Claims (1)

[Claims] (1) An electrophotographic photoreceptor in which a charge transfer layer, a charge generation layer, an intermediate layer, and a protective layer are sequentially provided on a conductive support, characterized in that an azo pigment represented by the following general formula is used in the charge generation layer. A photoreceptor for electrophotography. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [However, for A, there are ▲mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (Here, X is an aromatic ring such as a benzene ring or a naphthalene ring,
A hetero ring such as an indole ring, a carbazole ring, a benzofuran ring or a substituted product thereof, Ar_1 is a benzene ring,
Aromatic rings such as naphthalene rings, hetero rings such as dibenzofuran, or substituted products thereof, Ar_2 and Ar_3 are aromatic rings such as benzene rings and naphthalene rings, or substituted products thereof, R_1 and R_3 are hydrogen atoms, lower alkyl groups, phenyl groups or a substituted product thereof, R_2 represents a lower alkyl group, a carboxyl group, or an ester thereof). ]