JPS61204634A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and to reduce residual potential after durability test by forming an electrostatic charge generating layer contg. a specified polycyclic quinone type pigment and a charge transfer layer contg. a specified hydrazone compd. CONSTITUTION:The charge generating layer and the charge transfer layer is formed on a conductive substrate to prepare a laminated type electrophotographic sensitive body, and he charge generating layer contains the polycyclic quinone type pigments represented by formula I, and the charge transfer layer contains the hydrazone compd. This hydrazone type charge transfer material is represented by formula II in which each of R1, R2 is H, aryl, or optionally substd. heterocyclic, and each of R3, R4 is alkyl, aralkyl, aryl, or heterocyclic, each optionally substd., and R5 is a divalent org. residue. It is preferred to regulate its layer thickness to <=10mum in order to obtain sufficient light absorptivity, and as the binder to be used for forming this charge generating layer by coating, an org. photoconductor, such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, is used. the binder resin is used for the charge generating layer, preferably, in an amt. of <=80wt%, and the org. solvent to used for dissolving is alcohols, such as methanol, ethanol, or isopropanol, thus permitting the laminated type electrophotographic sensitive body high in sensitivity to be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an organic photoconductor, and particularly to an electrophotographic photoreceptor having a charge transport layer and a charge generation layer.

[Conventional technology]

Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been known so far.

On the other hand, since the discovery that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. For example, organic photoconductive polymers such as poly N-pynylcarnozole, polyvinylanthracene, carbazole, anthracene, pyrazolines, oxadiazoles,
Low-molecular organic photoconductors such as hydrazones 1, te IJ aryl alkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, or squaric acid methine dyes. Organic pigments and dyes are known. In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the range of options for selecting compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded. Photoconductive organic pigments and dyes have been proposed.

For example, US Pat. No. 4,123,270, US Pat. No. 42,476
No. 14, No. 4251613, No. 4251614, No. 4256821, No. 4260672, No. 4268596, No. 4278747, No. 429
As disclosed in Japanese Patent No. 3628, electrophotographic photoreceptors are known that use a disazo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer that is functionally separated into a charge generation layer and a charge transport layer.

Electrophotographic photoreceptors using such organic photoconductors can be produced by coating by appropriately selecting a binder, so it is possible to provide photoreceptors with extremely high productivity and at low cost. It has the advantage of being able to freely control the sensitive wavelength range.

A multilayer photoconductor obtained by laminating a charge transport layer and a charge generation layer mainly composed of a charge generation material has advantages over other single-layer photoconductors in terms of sensitivity and increased residual potential after durability tests. However, it was still not at a sufficient level.

[Problem that the invention seeks to solve]

An object of the present invention is to improve the above-mentioned drawbacks and provide a laminated electrophotographic photoreceptor with high sensitivity and extremely low residual potential even after a durability test.

The present invention aims to achieve the above object in a laminated electrophotographic photoreceptor having two layers, a charge generation layer containing a charge generation material as a main component and a charge transport layer containing a charge transport material as a main component, on a conductive support. This is achieved by using a specific polycyclic quinone pigment in the generation layer and a specific hydrazone compound in the charge transport layer.

[Means for solving problems]

The present invention provides a multilayer electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, in which the charge generation layer is composed of a layer containing a polycyclic quinone pigment represented by formula (1). The charge transport layer has the general formula (IF) (wherein R1 and R2 represent a hydrogen atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. R5 and R4 are substituted or unsubstituted heterocyclic groups). An unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted 5< represents an unsubstituted aryl group or a substituted or unsubstituted heterocyclic group. R5 represents a divalent organic residue.) This is an electrophotographic photoreceptor characterized by comprising a layer containing the hydrazo/type compound shown below.

The present invention will be explained in detail below.

In the laminated electrophotographic photoreceptor of the present invention, the charge generation layer contains as much charge generation material as possible in order to obtain sufficient absorbance, and efficiently injects generated charge carriers into the charge transport layer. Therefore, it is desirable to use a thin film layer, for example, a thin film layer having a thickness of 10 microns or less, preferably 0.01 micron to 1 micron. This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are not deactivated by recombination or trapping, but are transferred to the charge transport layer. This is due to the need for injection.

The charge generating material used in the present invention is a polycyclic quinone pigment represented by formula (I).

The charge generation layer can be formed by coating the above-mentioned pigment and, if necessary, a charge transporting material together with a suitable binder (or without a binder) on the substrate, and then forming a vapor-deposited film using a vacuum vapor deposition apparatus. You can get it by doing

The binder that can be used when forming the charge generating layer by coating can be selected from a wide variety of insulating resins and organic photoconductive polymers such as I-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin,
Polyamide, polyvinyl lysine, cellulose resin,
Examples include insulating resins such as urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is 80
Less than 40% by weight, preferably less than 40% by weight, is suitable.

It is preferable to select a solvent that dissolves these resins from a range of v, which varies depending on the type of resin, and a solvent that does not dissolve the underlying charge generation layer or undercoat layer. Specific organic solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and dimethylsulfoxide. sulfoxides such as tetrahydrofuran, dioxane, ethylene glycol, trimethyl ether, esters such as methyl acetate, ethyl acetate, aliphatic halodane such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichlorethylene, etc. Hydrocarbons or aromatic compounds such as benzene, toluene, xylene, ligroin, monochlorobenzene, and dichlorobenzenato can be used.

Coating methods include dip coating method, spray coach ink method, spinner coating method, peed coating method,
This can be carried out using a coating method such as a Mayer coating method, a blade coating method, a roller coating method, or a curtain coating method. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying can be carried out at 30° C. to 200° C. for a period of 5 minutes to 2 hours, either stationary or with air blowing.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and receiving charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. have. At this time, this charge transport layer may be laminated on or under the charge generation layer. However, since the charge transport layer is laminated on the charge generation layer, there is less deterioration of the surface of the photoreceptor during repeated durability, and furthermore, by selecting the binder in the charge transport layer, it is better. This is desirable in that it allows the formation of a photoreceptor surface with a uniform surface.

The substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport substance) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The term "electromagnetic waves" as used herein includes the broad definition of "light rays" including γ-rays, X-rays, far-infrared rays, and the like. When the photosensitive wavelength range of the charge transport layer is coincident with that of the charge generation layer, charge carriers generated in both layers trap each other, resulting in a decrease in sensitivity.

The charge transport substance used in the present invention is a hydrazone compound represented by general formula (n).

(In the formula, R1 and R2 represent a hydrogen atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted atom ring group. R3 and R4 represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, (R5 represents a divalent organic residue.) This hydrazone compound can be used as a charge transport substance under the above conditions. It has excellent properties, especially in terms of sensitivity and durability.

Typical hydrazicine compounds represented by the general formula (It) used in the present invention are illustrated in Table 1.

Further, in the present invention, the above-mentioned hydrazone compound used in the charge transport layer can be added to the charge generation layer, and the sensitizing effect thereof becomes even more remarkable.

When adding a charge transport material to the charge generation layer, the hydrazone compound should be 10 times or less (weight ratio), preferably 0.01 to 1 times (weight ratio) of the charge generation material to achieve high sensitivity, low residual potential, and repeatability. This is appropriate from the viewpoint of return stability.

To form a charge transport layer containing a hydrazone compound, a film can be formed by selecting an appropriate binder. Examples of resins that can be used as binders include acrylic resin, polyacrylate, polyester, and polycarp.
Nate? Listyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer,
Polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, ? Insulating resins such as lyamide and chlorinated rubber, or organic photoconductive materials such as poly-IJ-N-pynylcarnogzole, polyvinylanthracene, and polyvinylpyrene? Rimmer can be mentioned.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Typically it is 5 microns to 30 microns, with a preferred range of 8 microns to 20 microns. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a substrate having a conductive layer, that is, a conductive support. As the substrate having a conductive layer, the substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, dichloride, indium, gold, platinum, etc. In addition, a glass material (e.g., Riki-bon black, silver particles, etc.) having a layer formed by vacuum evaporation of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. is also suitable. A substrate coated on plastic with a binder, a substrate made of plastic or paper impregnated with conductive particles, a glass material containing a conductive polymer, etc. can be used.

A subbing layer having a rear function and an adhesive function can also be provided between the conductive layer and the photosensitive layer. Subbing layer C, casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66,
It can be formed from nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is suitably 0.1 to 40 microns, preferably 0.1 to 3 microns.

When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material in the charge transport layer is an electron transport material, it is necessary to positively charge the surface of the charge transport layer. When exposed to light after being charged, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the surface and neutralize the positive charge, causing the surface potential to attenuate and creating static between the unexposed area and the exposed area. Electrocontrast occurs. A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be directly fixed, or the toner can be transferred to paper, glass film, etc. and then developed and fixed.

Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or known methods, and are not limited to specific ones.

On the other hand, when the charge transport material consists of a hole transport material, it is necessary to charge the surface of the charge transport layer negatively. When exposed to light after charging, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. After that, it reaches the surface and neutralizes the negative charges, resulting in attenuation of the surface potential and an electrostatic contrast between it and the unexposed area.

During development, it is necessary to use a positively charged toner, contrary to the case where an electron transport material is used.

The electrophotographic photoreceptor according to the present invention is subject to deterioration due to ultraviolet rays, ozone, etc., stains due to oil, etc., scratches due to cutting powder of metal, etc., and exposure to hot water due to photoreceptor contact members such as developing members, transfer members, and cleaning members. A protective layer may be further provided on the charge generation layer or the charge transport layer for the purpose of preventing scratching and scratching. To form an electrostatic latent image on this protective layer,
It is desirable that the surface resistivity is 1011Ω or more.

The protective layer used in the present invention includes polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer The photosensitive layer can be formed by dissolving a resin such as the like in an appropriate organic solvent and coating the photosensitive layer and drying it.

Additionally, additives such as ultraviolet absorbers may be added to the resin liquid at a rate of 0.
The range is from 0.05 to 20 microns, particularly preferably from 0.2 to 5 microns.

Hereinafter, the present invention will be explained according to examples.

Example 1 Ammonia aqueous solution of casein (casein 11.2, 9, 28% ammonia water 1y1)
Water 222! IL1 was applied by a coating method and dried to form a subbing layer with a coating weight of 1.0 jiil/m2.

Next, 1 part by weight of the charge-generating material represented by formula (1), butyral goza (S-LEC BM-2:41 Suikagaku Co., Ltd. M)
) and 30 parts by weight of Improvil alcohol were dispersed for 4 hours using a Goal Mill disperser. This dispersion was applied onto the previously formed subbing layer by a dip coating method and dried to form a charge generation layer. The film thickness at this time was 0.3μ. Next, 1 part by weight of P-diethylaminobenzaldehyde-N-phenyl-α-su7tylhydrazone, which is Compound A (1) in Table 1, and polysulfo/resin (P1700
:Union carbide t+11m 'l 1 t4#
6 parts by weight of 1m J-monochlorpensef were mixed and dissolved by stirring with a stirrer.

This liquid was applied onto the charge generation layer by dip coating and dried to form a charge transport layer. The film thickness at this time is 1
It was 2μ.

Corona discharge of -5 kV was applied to the photoreceptor thus prepared. The surface potential at the time of (initial potential Vo) was measured.

Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay Vs). The sensitivity is determined by the exposure amount (E(72
tuxttee).

These results were as follows.

vo knee sss delt V5 knee 560 melt El/2: 5゜4 tuxHsec Examples 2-1
0 A photoreceptor was prepared in exactly the same manner as in Example 1, except that the compounds shown in Table 1 were used in place of the compound A (1) used in Example 1, and the characteristics of this photoreceptor were determined. was measured. These results are shown in Table 2.

Table 2 2 2 585 570
5. 63 3 590 575
6.24 4 595
585 6.45 5 580
565 5.76 6
585 570 5.47 7
575 560 5.58
8 570 555 5.99
9 580 565 5.8
10 10 575 560
6.3 Comparative Examples 1 to 6 Photoreceptors were prepared in exactly the same manner except that the charge transport materials shown in Table 3 were used in place of the hydrazone compound used in Example 1. The charging characteristics are shown in Table 4.

Table 3 Comparative Example Comparative Charge Comparative Charge Transport Material Structural Formula Transport Material MuC2H.

■ Table 4 m comparison example Comparative charge Vo (V) Vs (-V)
E+# Transport fj-A
tux-serel 1 5
90 565 7.42 2
580 550 7.03 3
590 565 7.64
4 605 580 8.15
5 585 560 7
．． 26 6 580 555
7.6 As is clear from the results of Examples and Comparative Examples, the laminated photoreceptor of the present invention is similar to the photoreceptors A1 to A6 of Comparative Examples.
It can be seen that a photoreceptor with extremely high sensitivity was obtained. Further, the photoreceptors of Examples 1 to 3 were used in a copying machine (NP-15
02: Image output using Canon Inc.)
Repeated 000 times. As a result, both photoreceptors had 200
Good quality images were obtained even after 00 repetitions. As a result, it can be seen that the photoreceptor of the present invention has extremely excellent durability.

〔Effect of the invention〕

As is clear from the above, the present invention uses a specific polynomial quinone-based pigment as a charge-generating material in the charge-generating layer and a specific hydrazone-based compound in the charge transport layer, thereby achieving extremely high sensitivity compared to conventional ones. This made it possible to provide a laminated electrophotographic photoreceptor.

Claims (2)

[Claims] (1) In a laminated photographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, the charge generation layer has the formula (
I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼It consists of a layer containing a polycyclic quinone pigment represented by (I), and the charge transport layer is the general formula (II).▲There are mathematical formulas, chemical formulas, tables, etc.▼(II ) (In the formula, R_1 and R_2 represent a hydrogen atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. R_3 and R_4 represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group) group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group.R_5 represents a divalent organic residue). Photographic photoreceptor. (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).