JPS63271355A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance photosensitivity and electric chargeability of an electrophotographic sensitive body by using an X-type metal-free phthalocyanine pigment as a charge generating material and a combination of specified compounds as a charge transfer material. CONSTITUTION:The photosensitive layer formed on a conductive supporting body contains as the charge generating material the X-type metal-free phthalocyanine and as the charge transfer material a combination of at least one of the compounds represented by formula I and at least one of the compounds represented by formula II, and in formula I, R1 is H atom, alkyl, or alkoxy group; R2 is H atom, alkyl, alkoxy group, halogen atom, or the like; and R3 is alkyl, alkoxy group, halogen atom, or the like, and in formula II, each of R4-R6 is H atom, alkyl, alkoxy group, halogen atom, or the like, thus permitting the obtained electrophotographic sensitive body to be superior in electrophotographic characteristics, such as photosensitivity, chargeability, stability of potential cycle, and residual potential, effective for various electrophotographic processes, high in flexibility, easy in manufacture, and low in cost.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor on which an electrostatic latent image is formed.

Conventional technology Conventionally, electrophotographic photoreceptors include selenium, selenium alloys,
Those using inorganic photoconductive materials such as zinc oxide and cadmium sulfide have mainly been used. However, electrophotographic photoreceptors using inorganic photoconductive materials have limited productivity, cost, and
Problems such as flexibility were common.

In recent years, in order to solve the drawbacks of inorganic photoconductive materials, research into electrophotographic photoreceptors using organic photoconductive materials has been actively conducted, and research on electrophotographic photoreceptors using organic photoconductive materials has been actively promoted. Electrophotographic photoreceptors using charge transfer complexes, electrophotographic photoreceptors using eutectic complexes of pyrylium salt and alkylidene diarylene, and the like are known.

In addition, X-type metal-free phthalocyanine pigments are α-type and β-type.
It has a higher charge generation efficiency than mold metal phthalocyanine, and its absorption extends to the long wavelength range, making it suitable as a photoreceptor for laser printers whose light source is a semiconductor laser with an emission spectrum around 800 nm. This is known, and an electrophotographic photoreceptor (Japanese Patent Publication No. 48-4338) in which it is dispersed in a binder resin is also known. Recently, electrophotographic photoreceptors have been proposed in which the functions of absorbing light and generating electric charges and transporting the generated electric charges are divided into separate materials.
i6247), for example, a laminated type containing a bisazo pigment/pyrazoline derivative has been put into practical use.

Problems to be Solved by the Invention However, electrophotographic photoreceptors using these organic photoconductive materials have low photosensitivity and are not yet satisfactory as photoreceptors. Furthermore, a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are functionally separated has not been found to be sufficiently satisfactory for practical use.

By the way, in order to obtain satisfactory electrophotographic properties in a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are functionally separated, as has been proposed in the past, 1. The charge generation material absorbs It is necessary to satisfy the following conditions: 2. The generated charge is efficiently injected into the charge transport material and transported. That is, even if condition 1 is satisfied, if condition 2 is not satisfied, satisfactory photoresponsiveness cannot be obtained.

In addition, when the electrophotographic photoreceptor is one in which a charge generation layer and a charge transport layer are laminated in this order, and light irradiation is performed from the charge transport layer side, the following conditions must be met in order to obtain high sensitivity:
It is necessary that the charge transport layer be sufficiently transparent to the light that activates the charge generation layer.

In order to create an electrophotographic photoreceptor using the above-mentioned known charge-generating materials and charge-transporting materials, it is necessary to satisfy the above-mentioned conditions, such as sensitivity, acceptance potential, potential retention, potential stability, and residual A combination of materials that satisfies all aspects, including electrophotographic properties such as potential and spectral properties, usage properties such as strength, durability, and stain resistance, and manufacturing stability and quality stability when manufactured by coating. Choosing a match is extremely difficult.

For example, many materials have been proposed that satisfy Condition 1 above, and disazo pigments such as chlordian blue are known to have relatively high charge generation efficiency, but they are used in high-speed copying machines. However, it still did not have sufficient photoresponsiveness.

Regarding the charge transport layer, even if the charge generation material generates sufficient charge, satisfactory electrophotographic properties cannot be obtained unless it is combined with a charge transport material that efficiently injects and transports the charge. It is known that the injectability in condition 2 is related to the difference in ionization potential between the charge generating material and the charge transporting material to some extent, but this is only a result between predetermined materials, and - It lacks lethality, and its relationship with electrophotographic properties has not yet been clarified. This is considered to be because the injection property largely depends on other properties of the charge generating material and the charge transporting material. And as an electrophotographic photoreceptor,
It is believed that the degree of influence of factors that affect injectability differs among various materials, and the effect of improving injectability is also not uniform.

The present invention was made in view of the above-mentioned circumstances, and by finding a combination of materials that satisfies all of the requirements for an electrophotographic photoreceptor, excellent electrophotography can be achieved. The purpose is to provide a photoreceptor.

That is, an object of the present invention is to provide an electrophotographic photoreceptor that has excellent electrophotographic properties such as photosensitivity, chargeability, potential cycle stability, and residual potential, and is effective in various electrophotographic processes.

Another object of the present invention is to provide an electrophotographic photoreceptor with high sensitivity, high flexibility, easy manufacture, and low cost.

Means for Solving the Problems The present inventors have developed an X-type metal phthagocyanin, which has high charge generation efficiency but has low mobility and is insufficient for practical use to transport the generated charges. Focusing on pigments, we conducted studies on charge transport materials that, when used in combination with this X-type metal-free phthalocyanine pigment, would yield an electrophotographic photoreceptor with excellent electrophotographic properties.As a result, we found that the following general formula ( I
The inventors have discovered that the above object can be achieved by using the compound represented by formula (II) in combination with the compound represented by general formula (II), and have completed the present invention.

The electrophotographic photoreceptor of the present invention comprises a photosensitive layer provided on a conductive support, and the photosensitive layer contains an X-type metal-free phthalocyanine pigment as a charge-generating material, and as a charge-transporting material, It is characterized by containing at least one compound represented by the following general formula (1) and at least one compound represented by the following general formula (, I[>).

(In the formula, R1 represents a hydrogen atom, an alkyl group, or an alkoxy group, R2 represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group, or a substituted amino group, and R3 represents an alkyl group, an alkoxy group, or a halogen The present invention will be described in detail below.

The X-type metal-free phthalocyanine pigment used in the present invention is disclosed in Japanese Patent Publication Nos. 44-14106 and 49-433
Refers to a metal-free phthalocyanine described in Publication No. 8 and having a crystal form defined as type X.

On the other hand, the following compounds are exemplified as compounds represented by the general formula (I).

■-+ I-2r
-3I-4 Knee 7 I
-81-el/i-8
'd Also, as the compound represented by the general formula (II>), the following are exemplified.

+1- + II-
2I+-3]-4 n-s n-ell-7
I[-8 11-91[-40 '9'''It-251-;'6 In the present invention, the X-type gold metal phthalocyanine pigment described above has the general formula (
The compounds represented by I> and (II> are contained in the photosensitive layer formed on the conductive support, but the photosensitive layer contains the third
It may have a single layer structure as shown in the figure, or it may have a functionally separated laminated structure as shown in FIGS. 1 and 2.

However, the latter is preferred in order to obtain better electrophotographic properties.

In FIG. 1, a charge generating material 2 is placed on a conductive support 1.
A charge generation layer 3 containing a charge transport material 4 is formed thereon, and a charge transport layer 5 containing a charge transport material 4 is formed thereon, and is used as a negatively charged type.

In FIG. 2, contrary to FIG. 1, a charge transport layer 5 containing a charge transport material 4 is formed on a conductive support 1, and a charge generation layer containing a charge generation material 2 is formed thereon. It is used as a positively charged type.

In FIG. 3, a photoconductive layer 6 is formed on a conductive support 1, and a charge generating material 2 is provided in the photoconductive layer.
and charge transport material 4 are contained in a mixed state. This material can be used either positively or negatively charged, but a positively charged one is preferred.

The conductive support used in the present invention is a metal plate, metal drum, or metal foil made of aluminum, nickel, chromium, stainless steel, etc., and aluminum, titanium, nickel, chromium, SUS, gold, vanadium, tin oxide, or Examples include a plastic film provided with a thin film of indium, ITO, etc., or paper or plastic film coated with or impregnated with a conductivity imparting agent.

The charge generation layer is formed by dispersing an X-type metal-free phthalocyanine pigment in a binder resin solution and coating the solution. As the dispersion means, commonly used ones such as a ball mill, roll mill, sand mill, attritor, etc. can be used. The compounding ratio of the X-type metal-free phthalocyanine pigment and the binder resin is 4Q:1 to 1:10. Preferably 20:1-1
:3. If the ratio of the X-type metal-free phthalocyanine pigment is too high, the stability of the coating solution will decrease, and if it is too low, the sensitivity will decrease, so it is desirable to keep it within the above range. Further, as the solvent for the binder resin, any solvent can be used as long as it is soluble and can be applied, but it is desirable to select a solvent that has good pigment dispersibility.

Further, a plurality of solvents may be used in combination.

Examples of the binder resin include well-known ones such as polycarbonate, polystyrene, polyester, polyvinyl butyral, methacrylic acid ester polymer or copolymer, vinyl acetate polymer or copolymer, cellulose ester or ether, polybutadiene, polyurethane, and epoxy resin. etc. are used. A plurality of these may be used in combination.

The particle size of the X-type metal-free phthalocyanine pigment after dispersion is 1
It is preferably less than μm. If the particle size is too large, it may cause a decrease in the stability of the paint, poor image quality, etc.

The thickness of the charge generation layer ranges from 0.01μTrt to 5μ,
Preferably it is about 0.03 μTrL to 2 μm.

If the film thickness is larger than the above range, problems such as a decrease in chargeability, an increase in dark decay, and a decrease in repetition stability will occur, and if it is smaller, the sensitivity will decrease.

The charge transport layer is formed by dispersing at least one compound represented by the general formula (I>) and at least one compound represented by the general formula (II) in a film-forming resin. Although both compounds can be used in any mixing ratio, it is preferable to use them in approximately equal amounts.

In addition, the blending ratio of these two compounds and resin is 5:1 to 5:1.
The ratio is 1:5, preferably 3:1 to 1:3. If the former ratio is too high, the mechanical strength of the charge transport layer will decrease, and if it is too low, the sensitivity will decrease, so it is desirable to keep it within the above range.

The film-forming resin is a resin that is used to prevent film formation because the compound itself does not have film-forming properties, and is highly compatible with the compound and has high film-forming properties. I don't care what I am. Examples of resins that can be used include polycarbonate, polyacrylate, polyester, polystyrene, styrene-acrylonitrile copolymer, polysulfone, polymethacrylate, styrene-methacrylate copolymer, and vinyl polymer.

The charge transport layer is prepared by dissolving the compound and resin in a solvent,
Formed by coating. The solvent used varies depending on the resin, but the following solvents may be used as long as they can dissolve both the compound and the resin.

The thickness of the charge transport layer is preferably about 5 to 50 μm.

In the electrophotographic photoreceptor of the present invention, it is often preferable to provide a barrier layer between the photosensitive layer and the conductive support. The barrier layer is effective in preventing unnecessary charge from being injected from the support, and has the effect of increasing the chargeability of the photosensitive layer and improving image quality. Furthermore, it also has the effect of improving the adhesion between the photosensitive layer and the conductive support. Materials constituting the barrier layer include polyvinyl alcohol, polyvinylpyrrolidone, polyvinylpyridine, cellulose ethers, cellulose esters, polyamide, polyurethane, cavin, gelatin, polyglutamic acid, starch, starch acetate, aminostarch, polyacrylate, Examples include polyacrylamide, silane coupling agents, zirconium chelates, and titanium chelates.

The resistivity of these materials is preferably about 10 5 to 10 14 Ω·cm. The thickness of the barrier layer is set to about 0.01 to 2 μm.

Furthermore, if necessary, a protective layer may be provided on the photosensitive layer. This protective layer is used to prevent chemical deterioration of the photosensitive layer having a laminated structure during charging and to improve the mechanical strength of the photosensitive layer.

The protective layer is formed by containing a conductive material in a suitable binder. As the conductive material, metallocene compounds such as N,N=-dimethylferrocene, N,N'-diphenyl-N,N--bis-(3-methylphenyl)-[
Materials such as aromatic amino compounds such as 1,1"-biphenyl]-4,4"-diamine, metal oxides such as antimony oxide, tin oxide, titanium oxide, indium rat, and tin oxide-antimony oxide may be used. However, it is not limited to these. Further, as the binder resin used for this protective layer, known resins such as polyamide resin, polyurethane, polyester resin, epoxy resin, polyketone resin, polycarbonate, polyvinyl ketone resin, polystyrene, polyacrylamide resin, etc. can be used.
It is not limited to these.

This protective layer has an electrical resistance of 109 to 1014 Ω・c
It is preferable to configure it so that it becomes m. electrical resistance is 1
If it exceeds 0.014 Ωcm, the residual potential will increase, resulting in copies with a lot of fog, and 109 Ω.CI! If it is less than that, the image will become blurred and the resolution will decrease. Furthermore, this protective layer must be constructed so as not to substantially obstruct the passage of light used for imagewise exposure.

The thickness of the protective layer used in the present invention is 0.5 to 20μ
, preferably in the range of 1 to 10μ.

This protective layer can be formed by a commonly used coating method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, or a curtain coating method.

According to the present invention, as a charge transport material, the above general formula (1
) and at least one compound represented by the above general formula (II>), the charge generation efficiency is high, but the charge transportability is low;
It is presumed that the defect of the X-type non-metallic phthalocyanine, which had a substantially low sensitivity, namely, the low charge transport ability, is compensated for, and an electrophotographic photoreceptor having a substantially high sensitivity can be obtained.

Example Hereinafter, the present invention will be explained by examples.

Example 1 1 part by weight of an X-type metal-free phthalocyanine pigment, 10 parts by weight of a 10% by weight cyclohexanone solution of polyvinyl butyral resin (B-90: Mitsubishi Sensanto Kasei ■), and 60 parts by weight of cyclohexanone were mixed into 5 parts by weight using a grinder mill.
The resulting dispersion was applied to an aluminum sheet using an applicator and dried at 120° C. for 10 minutes to form a charge generation layer. When the film thickness was measured, it was 0.4 μm. Next, 3 parts by weight of each of the exemplary compounds 1-36 and 1-19 and 4 parts by weight of polycarbonate resin (trade name: Lexan 145° manufactured by GE; molecular weight 35,000/40,000) were dissolved in 40 parts by weight of dichloromethane. In addition to the obtained solution, the obtained coating liquid was applied onto the charge generation layer using an applicator to form a charge transport layer. After drying at 120″C for 1 hour,
When the film thickness was measured, it was found to be 21 μm.

The electrophotographic photoreceptor sheet produced in this way was
It was wrapped around a φ aluminum pipe and evaluated using an electrophotographic property evaluation device as follows.

First, the photoreceptor was charged so that the inflow current was 110 μA, and the surface potential was measured 1 second after charging, and VpO (volt) was measured.
And so. Thereafter, static electricity was removed using a tungsten lamp, and the potential after static electricity removal was measured, and this was defined as the residual potential VR. This operation was repeated 100 times to examine repeat stability.

Next, the charging current was adjusted so that VPO was -800V, and 800 nm monochromatic light was exposed to IE at 0.3 seconds after charging.
(erg/crit) and after exposure 09
The potential at 7 seconds (1 second after charging) was measured, and the decay rate of the potential from VPO was calculated as dV/dE. The results are shown in Table 1.

Comparative example 1 Polycarbonate (Bisphenol Z type.

A coating liquid was prepared by dissolving 10 parts by weight of 130,000 molecules in 40 parts by weight of monochlorobenzene, adding 1 part by weight of X-type metal-free phthalocyanine thereto, and dispersing for 2 hours using a paint shaker.

This coating solution was applied onto an aluminum sheet using a wire bar and dried to form a photoconductive layer having a thickness of 19 μm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Comparative Examples 2 and 3 As the charge transport material, each of the exemplified compounds Ni36 and I[-19 used in Example 1 was used alone. That is, 3 parts by weight of one of these compounds and a polycarbonate resin (trade name: NILEXAN 145, made by GE; molecular weight 35,000-40,000 > 4 parts by weight) were dissolved in 28 parts by weight of dichloromethane, and the resulting coating solution was used in Example An electrophotographic photoreceptor sheet was prepared by coating the charge generation layer formed in the same manner as in Example 1.The obtained electrophotographic sheet was evaluated in the same manner as in Example 1.The results are shown in Table 1. Shown below.

Comparative Example 4 Except for using Exemplary Compound Ni 2 as the charge transport material,
An electrophotographic photoreceptor sheet was produced in the same manner as in Comparative Example 2, and evaluated in the same manner.

The results are shown in Table 1. Note that the combination of charge generation material and charge transport material in this comparative example is disclosed in Japanese Patent Application Laid-Open No. 58-16
It is the same as that disclosed in Publication No. 2478.

Examples 2 to 4 Electrophotographic photoreceptor sheets were prepared in the same manner as in Example 1, except that the combinations of compounds shown in Table 1 were used as charge transport materials, and evaluations were performed in the same manner.

The results are shown in Table 1.

Table 1 ← 1■ From the results in Table 1, it can be seen that in the case of the present invention in which the compounds represented by general formulas (1) and (II) are used in combination, the Light sensitivity (dV/dE)
It can be seen that the chargeability and charging property (VPO2>) are improved.

Effects of the Invention In the present invention, as is clear from the comparison between Examples and Comparative Examples, an X-type metal-free phthalocyanine pigment is used as a charge-generating material, and a compound represented by general formula (I) is used as a charge-transporting material. By using both of the compounds represented by general formula (II) in combination, the photosensitivity of the photoconductive layer using the X-type metal-free phthalocyanine pigment increases, and when both of the above compounds are used alone The effect is that the photosensitivity and chargeability of the electrophotographic photoreceptor are improved. Further, the electrophotographic photoreceptor of the present invention is excellent in potential cycle stability and residual potential, and is highly flexible and easy to manufacture.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are schematic diagrams for explaining the structure of the electrophotographic photoreceptor of the present invention, respectively. DESCRIPTION OF SYMBOLS 1... Conductive support body, 2... Charge generating material, 3...
- Charge generation layer, 4... Charge transport material, 5... Charge transport layer, 6... Photoconductive layer. Patent applicant Fuji Xerox Co., Ltd. Agent
Patent Attorney Tsuyoshi Watanabe Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive support, the photosensitive layer contains an X-type metal-free phthalocyanine pigment as a charge-generating material, and as a charge-transporting material, the photosensitive layer has the following general formula: An electrophotographic photoreceptor comprising at least one compound represented by (I) and at least one compound represented by the following general formula (II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R_1 represents a hydrogen atom, an alkyl group, or an alkoxy group, and R_2 represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group, or a substituted amino group, and R_3 represents an alkyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group, or a substituted amino group) ▲There are numerical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R_4, R_5, and R_6 are each (Represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group, or a substituted amino group.) (2) A charge generation layer containing an X-type metal-free phthalocyanine pigment on a conductive support, and at least one compound each of the compound represented by the above general formula (I) and the above general formula (II). 2. The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is formed by sequentially laminating charge transport layers containing two charge transport layers.