JPS61292148A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and to extremely reduce residual potential even after durability test by incorporating a specified polycyclic quinone type pigment in an electrostatic charge generating layer, and a specified hydrazone derivative in a charge transfer layer. CONSTITUTION:A laminate type electrophotographic sensitive body is prepared by forming on a conductive substrate the charge generating layer containing the polycyclic quinone type pigment represented by structural formula (I), and the charge transfer layer containing the hydrazone derivative represented by general formula (II) in which R1, R2 are each H, halogen, nitro, alkoxy, aryloxy, or amino; R3, R4 are each alkyl or aryl; and each of R5, R6, R7, R8 is H, halogen, nitro, alkyl, alkoxy, aryloxy, acyl, or amino. When the charge transfer material is added to the charge generating layer, it is suitable to add the hydrazone derivative in an amount of <=10 times, preferably, 0.01-1 time the weight of the charge generating material from the viewpoints of high sensitivity, low residual potential, and stability against repeated uses.

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 generation layer and a charge transport layer.

[Prior Art] Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been known. 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-vinylcarbazole and polyvinylanthracene, low-molecular organic photoconductors such as carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, and polyarylalkane, and phthalocyanine pigments. Organic pigments and dyes such as , azo pigments, cyanine pigments, polycyclic pigments, perylene pigments, indigo dyes, thioindigo dyes, and squaric acid methine dyes are known. especially,
Organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in the appropriate wavelength range has been expanded, so there are many photoconductive materials. Organic pigments and dyes have been proposed.

For example, US Patent No. 4123270, US Patent No. 424761
No. 4, No. 4251613, No. 4251614,
Same No. 4256821, Same No. 4260672, Same No. 4
No. 268596, No. 4278747, No. 4293
As disclosed in No. 628, etc., 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.

An electrophotographic photoreceptor using such an organic photoconductor can be produced by coating by appropriately selecting a binder, so it is possible to provide an extremely highly productive and inexpensive photoreceptor.
Moreover, it has the advantage that the sensitive wavelength range can be freely controlled by selecting the organic pigment.

A multilayer photoreceptor obtained by laminating a charge transport layer and a charge generation layer mainly composed of a charge generation material has a higher sensitivity and a lower residual potential after durability tests than other single layer photoreceptors.
Although it is advantageous in terms of promotions, etc., it is still not at a sufficient level.

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

[Means and effects for solving the problems] The present invention achieves the above object by forming 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 charge generation layer and a specific hydrazone compound in the charge transport layer in a laminated electrophotographic photoreceptor having two layers.

The present invention provides a laminated 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 comprised of a layer containing a polycyclic quinone pigment of structural formula (I). , the charge transport layer is a hydrazone compound represented by the general formula (II) (wherein R5 and RY represent a hydrogen atom, a halogen atom, a nitro group, an alkoxy group, a substituted or unsubstituted amino group, provided that R1 and At least one of R2 is a substituted amino group or an alkoxy group.R3 and Machi represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group.However, at least one of R3 and Machi is a substituted or unsubstituted aryl group. It is an unsubstituted aryl group. Also, R3 and R
+ may complete the nitrogen-containing heterocycle. R,, R6, R7
and R♂ is a hydrogen atom.

halogen atom, nitro group, substituted or unsubstituted alkyl group, alkoxy group, substituted or unsubstituted aryloxy group, substituted or unsubstituted acyl group, or substituted or unsubstituted amino group) It consists of an electrophotographic photoreceptor characterized by:

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 in order to efficiently inject the generated charge carriers into the charge transport layer. to a thin film layer, e.g. 1OIL
Hereinafter, it is preferable to use a thin film layer having a thickness of preferably 0°01-1 g.

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 injected into the charge transport layer without being deactivated by recombination or trapping. This is due to the need to do so.

The charge generating material used in the present invention is a polycyclic bovine non-based pigment represented by the structural formula.

The charge generation layer can be formed by coating the above-mentioned pigment and, if necessary, a charge transport material together with a suitable binder (or without a binder) on a substrate, or by forming a vapor deposited film using a vacuum vapor deposition device. can be obtained by

The binder that can be used in forming the charge generating layer by coating T can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

Preferably, polyvinyl butyral, polyarylate (
polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol,
Insulating resins such as polyvinylpyrrolidone can be mentioned.

The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

The solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the above-mentioned charge transport layer or undercoat layer.

Specific organic solvents include methanol, ethanol,
Alcohols such as isopropanol, ketones such as acetone, methyl ethyl ketone, cyclohexanone, N, N
-dimethylformamide, N.

Amides such as N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate,
Chloroform, methylene chloride, dichloroethylene, 4m
Aliphatic halogenated hydrocarbons such as carbon dioxide and trichloroethylene, or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using a coating method such as a Mayer bar 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 a temperature of 30 to 200° C. for a period of 5 minutes to 2 hours, either stationary or with ventilation.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and taking 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.

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 matches or overlaps that of the charge generation layer, charge carriers generated in both layers are trapped in phase η, resulting in a decrease in sensitivity.

The charge transport substance used in the present invention has the general formula (II)
It is a hydrazone compound represented by

(In the formula, R1 and R2 represent a hydrogen atom, a halogen atom, a nitro group, an alkoxy group, or a substituted or unsubstituted amine group. However, at least one of R1 and R2L is a substituted amino group or an alkoxy group. □ and R+ represent a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.However, at least one of R3 and Machi is a substituted or unsubstituted aryl group.
3 and Machi may complete the nitrogen-containing heterocycle. R,,Rj,
R7 and Re represent a hydrogen atom, a halogen atom, a nitro group, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted amino group ).

This hydrazone compound satisfies the above-mentioned conditions as a charge transport material, and has excellent properties particularly in terms of sensitivity and durability.

Representative examples of the hydrazone compounds used in the present invention are shown below.

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

When a charge transporting material is added to the charge generation layer, the hydrazone compound is preferably 10 times or less (weight ratio), preferably 0.01 to 1 times (weight ratio) of the charge generation material, to provide high sensitivity, low residual potential, This is appropriate from the viewpoint of repeated stability.

To form a charge transport layer containing the above hydrazone compound, a film can be formed by selecting an appropriate binder.

Resins that can be used as binders include, for example, acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, etc. Insulating resin or poly-N-vinylcarbazole,
Organic photoconductive polymers such as polyvinylanthracene and polyvinylpyrene may be mentioned.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary.

Generally it is 5 to 30 l, but the preferred range is 8 to 2
It is 0 sutra.

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 -L of a substrate having a conductive layer.

As the substrate having the conductive layer, materials that are conductive themselves such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used. In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, Polyfluorinated ethylene, etc.), conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic with a suitable binder, substrates made of plastic or paper impregnated with conductive particles, and plastics with conductive polymers. etc. can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer.

The undercoat layer is casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon,
Alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is 0.1 to 40. , preferably 0.1~
3 is appropriate.

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, the surface of the charge transport layer must be positively charged. When exposed to light after being charged, electrons generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, causing a decrease in surface potential and creating an electrostatic charge between the exposed area and the unexposed area. Contrast occurs.

A visible image is obtained by developing the electrostatic latent image thus formed with a negatively charged toner.

This can be directly fixed, or the toner image can be transferred to paper, plastic 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, and then visually imaged and fixed.

The type of developer, the developing method, and the fixing method may be any known ones or methods, and are not limited to specific ones or methods.

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

In contrast to the case where an electron transport material is used, it is necessary to use a positively charged toner in the developing section.

The electrophotographic photoreceptor according to the present invention suffers from deterioration due to ultraviolet rays, ozone, etc., dirt from oil, etc., scratches from metal chips, etc., and damage to the photoreceptor from photoreceptor contact members such as developing members, transfer members, and cleaning members. A protective layer may be further provided on the charge generation layer-F for the purpose of preventing scratching.

In order to form an electrostatic latent image on this protective layer, it is desirable that the surface resistivity is 10ゝゝΩ or more -L.

The protective layer used in the present invention is made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-
It can be formed by applying a solution prepared by dissolving a resin such as an acrylic acid copolymer or a styrene-acrylonitrile copolymer in a suitable organic solvent onto one of the photosensitive layers and drying it.

Moreover, additives such as ultraviolet absorbers can be added to the resin liquid.

At this time, the thickness of the protective layer is generally in the range of 0.05 to 20 mm, preferably 0.2 to 5 mm.

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

Example 1 An ammonia aqueous solution of casein (2 g of casein 11, 28% ammonia Ig, 222 ml of water) was coated on an aluminum cylinder by dip coating, and dried to form a subbing layer of 11.0 g/m. Formed.

Next, a single layer of charge generating material of structural formula (I).

Butyral resin (Eslec BM-2, manufactured by Miki Kagaku ■)
1 part by weight and 30 parts by weight of isopropyl alcohol were dispersed for 4 hours using a ball mill disperser.

This dispersion was applied to one of the previously formed subbing layers by a dip coating method and dried to form a charge generation layer. The film thickness was 0.3.

Next, compound 1 of the above-mentioned hydrazone compound example (1) weight 1. 1 part of polysulfone (P1700, manufactured by Union Carbide) and 6 parts by weight of monochlorobenzene 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.

This film thickness was 12 mm.

A corona discharge of 15 KV was applied to the photoreceptor thus prepared.

The surface potential at this time (initial potential V6) was measured.

Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay V).

Sensitivity was evaluated by measuring the amount of exposure (E 1/21ux, 5ec) required to attenuate the potential W after dark decay to 1/2.

These results were as follows.

Va mini-595, V: -585V.

E 1/2 Near, Olux, sec Examples 2 to 5 Examples 2 to 5 except that hydrazone compound examples (2) to (5) were used in place of hydrazone compound example (1) used in Example 1, respectively. A photoreceptor was prepared in exactly the same manner as in Example 1, and the characteristics of this photoreceptor were measured.

These results are shown below.

'IJI! U Side hole 1 Vo -V V -V E
1/2 lux 5ec2 (2) 8
00 590 8.83 (3) 8
00 585 7.44 (4) 6
05 595 7.25 (5) 61
0 800 7.8 Comparative Examples 1 to 6 Comparative Examples 1 to 6 were carried out in exactly the same manner except that the following comparative charge transport substances (1) to (6) were used in place of the hydrazone compound used in Example 1. A photoreceptor was prepared and its charging characteristics were measured.

H Charging characteristics 1 (1) E105 580 9
．． 22 (2) 590 570
8.113 (3) 585 585
11.04 (4) El15
51115 9.75 (5) BO
G 575 111.18 (6)
5135 585 13.3 As is clear from the results of Examples and Comparative Examples, the laminated photoreceptor of the present invention has the following properties:
It can be seen that a photoreceptor with extremely high sensitivity was obtained compared to the photoreceptors of Comparative Examples 1 to 6.

Further, the photoreceptors of Examples 1 to 5 were manufactured by Canon Corporation, N
Image production was repeated 20,000 times using a P-1502 copying machine.

As a result, good quality images were obtained even after repeating the test 20,000 times with each photoreceptor, indicating that the photoreceptor of the present invention has extremely excellent durability.

[Effects of the Invention] As is clear from the above, the present invention uses a specific polycyclic quinone pigment as a charge generation material in the charge generation layer, and (1) uses a specific hydrazone compound in the charge transport layer. This makes it possible to provide a laminated electrophotographic photoreceptor with extremely high sensitivity compared to conventional ones.

Claims (2)

[Claims] (1) In a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, the charge generation layer consists of a layer containing a polycyclic quinone pigment of structural formula (I), and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) Hydrazone compounds whose charge transport layer is represented by the general formula (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) (In the formula, R_1 and R_2 are hydrogen atoms , halogen atom,
It represents a nitro group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted amino group. However, at least one of R_1 and R_2 is a substituted amino group or an alkoxy group. R_3 and R_4 represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. However, at least one of R_3 and R_4 is a substituted or unsubstituted aryl group. Further, R_3 and R_4 may complete a nitrogen-containing heterocycle. R_5, R_6, R_7 and R_8 are hydrogen atoms, halogen atoms, nitro groups, substituted or unsubstituted alkyl groups,
It represents an alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted amino group. ) An electrophotographic photoreceptor comprising a layer containing: (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).