JPS6228739A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain high sensitivity and superior durability by using a specified polycylic quinone pigment as a charge generating material in a charge generating layer and incorporating a specified hydrazone compound into a charge transferring layer. CONSTITUTION:A polycyclic quinone pigment represented by formula I is incorporated into the charge generating layer of the laminate type electrophotographic sensitive body, and a hydrazone compound represented by formula II [where each of R1 and R2 is H, halogen, nitro, (un)substituted aryloxy, alkoxy or substituted amino; one or more between R1 and R2 are substituted amino or alkoxy; each of R3 and R4 is (un)substituted alkyl or aryl; one or more between R3 and R4 are aryl; R3 and R4 may bond to each other to form a heterocyclic ring contg. N; and each of R5-R8 is H, halogen, nitro, (un)substituted alkyl, alkoxy, aryloxy, acyl or amino] is incorporated into the charge transferring layer. The resulting laminate type sensitive body has high sensitivity and superior durability. The hydrazone compound represented by the formula II may also be incorporated into the charge generating layer so as to produce a further remarkable sensitizing effect.

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-vinylcarbazole, polyvinylanthracene, carbazole,
Anthracene, pyrazolines, oxadiazoles, hydrazones,? Organic pigments and dyes such as low-molecular organic photoconductors such as realyl alkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and squaric acid methine dyes are used. It is known that organic pigments and dyes that exhibit photoconductivity are easier to synthesize than inorganic materials, and the range of variations in which compounds that exhibit photoconductivity in an appropriate wavelength range can be selected has been expanded. Because of this,
A number of photoconductive organic pigments 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 control the entire photosensitive wavelength range at will.

The laminated photoreceptor, which is obtained by laminating a charge transport layer and a charge generation layer mainly composed of a charge generation material, is different from other single layer photoreceptors due to its sensitivity and increased residual potential after durability tests. Although it was advantageous, it was still not at a sufficient level.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION 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 consists of a layer containing a polycyclic quinone pigment expressed in a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, and the charge transport layer has the general formula (TI ) 3R4 (wherein R4 and R2 are a hydrogen atom, a halogen atom,
A nitro group, an aryloxy group which may have a substituent, and an alkoxy group indicate a substituted amine group.

However, at least one of R4 and R2 is an amine group or an alkoxy group. R3 and R4 each represent an aryl group, as many as i argyl groups which may have substituents. However, at least one of R3p and R4 is an aryl group. Further, R3 and R4 may be combined to form a nitrogen-containing heterostructure. R5, R6, R.

and R8 each represent a hydrogen atom, a rhodane atom, a nitro group, an alkyl group which may have a substituent, an alkoxy group, an aryloxy group, an acyl group, or an amino group.

) This is an electrophotographic photoreceptor characterized by comprising a layer containing a hydrazone compound represented 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 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 transported by recombination or trapping without being deactivated. This is due to the need to inject into the layer.

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 to form the charge generating W1 by coating can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarnofsol, polyvinylanthracene, and privinylpyrene. Preferably polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and 7-talic acid, etc.)
, polycarbonate, polyester, phenoxy resin,
Examples include insulating resins such as polyvinyl acetate, acrylic resin, polyacrylamide resin, polyvinyl pyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is
It is suitable that the weight is less than 40% by weight, preferably less than 40% by weight.

The solvent for dissolving these resins varies depending on the ffI of the resin, and it is preferable to select a solvent that does not completely dissolve the charge generation layer or undercoat layer. Specific organic solvents include alcohols such as methanol, ethanol and ingropanol; ketones such as a7tone, methyl ethyl ketone and cyclohexanone; amides such as N,N-dimethylformamide and N,N-dimethylacetamide;
Sulfoxides such as dimethyl nulphoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, and fats such as chloroform, methylene chloride, dichlorobenzene, carbon tetrachloride, and trichloroethylene. In the case of rhodinized hydrocarbons, benzene, toluene,
Aromatic compounds such as 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 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 ventilation.

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 in surface trenches. I have 2. 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" used herein includes the broad definition of "light rays" including r-rays, X-rays, far-infrared rays, and the like. When the photosensitive wavelength range of the charge transport layer coincides with or overlaps 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 the general formula (ff).

(In the formula R1p R2t R3P R4y R5t R6
p R7p RB is as described above), where the alkoxy group is preferably an alkoxy group having lower alkyl. Examples of the substituted amino group include dimethylamino, diethylamino, dibenzylamino, and the like.

The alkyl group is preferably a lower alkyl group, and the aryl group is exemplified by phenyl, diphenyl, naphthyl, and the like. Examples of the nitrogen-containing heterocycle include pyrrolidino, piperidino, and morpholino. Also, an alkyl group,
The aryl group, aryloxy group, acyl, and amino group may be further substituted with other substituents such as halogen, a, v-kyl, aryl, and the like.

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

Table 1 shows typical hydrazone compounds represented by the general formula (IF) used in the present invention.

Table 1 & Table 1b 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 transporting 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 substance 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. Resins that can be used as binders include, for example, acrylic resins, polyacrylates, polyesters, polycarbonates, polystyrenes, acrylonitrile-styrene copolymers, acrylonitrile-butadiene copolymers,
Examples include insulating resins such as polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, and chlorinated rubber, and organic photoconductive polymers such as -so-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

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 has a conductive 'f! It is provided on a substrate having one layer, ie a conductive support. Examples of the substrate having a conductive layer include those whose substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium,
Molybdenum, chromium, titanium, nickel, indium,
Gold, platinum, etc. can be used, and in addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. can be used to form a six-layer glass film by vacuum deposition (e.g., carbon black, A substrate in which plastic is coated with silver particles (silver particles, etc.) together with a suitable binder, a substrate in which plastic or paper is impregnated with conductive particles, a plastic having a conductive polymer, etc. can be used.

An undercoat flt having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The undercoat layer is made of 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 suitably 0.1 micron to 40 micron, preferably 0.1 micron to 3 micron.

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 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 the extreme R 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, and when exposed to light after charging, the holes generated in A in the charge generation layer transport charges in the exposed area. It is injected into the layer and then reaches the surface to neutralize the negative charges, resulting in a decay of the surface potential and an electrostatic contrast with the unexposed areas.

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., dirt due to oil, etc., scratches due to cutting powder of metal, etc., and damage to the photoreceptor due to photoreceptor contact members such as developing members, transfer members, cleaning members, etc. A protective layer may be further provided on the charge generation layer or the charge transport layer for the purpose of preventing 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 teribinyl butyral, polyester, polycarnate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane 1, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer. The photosensitive layer can be formed by dissolving a resin such as the following in an appropriate organic solvent and coating the photosensitive layer with the solution 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 0.05~
20 microns, particularly preferably in the range 0.2 to 5 microns.

Hereinafter, the present invention will be explained according to examples. ◇Example 1 Casein ammonia 71 on aluminum cylinder
i (casein 11.2%, 28% ammonia water 151'
- 222 mA of water) was coated with 100 mA of water and dried to form the entire undercoat layer with a coating amount of 100 mA.

Next, 1 part by weight of the charge generating substance represented by formula (1), butyral resin (S-LEC BM-2: Sekisui Chemical Co., Ltd. M)
) 1 part by weight and 30 parts by weight of Improvil alcohol were dispersed for 4 hours after dispersing with Lumyl. This dispersion was applied onto the previously formed subbing layer by a dip coating method and dried to form a charge generating layer. The film thickness at this time is 0.3μ
Met. Next, 1 part by weight of the hydrazone compound of Compound A (1) in Table 1, 1 part by weight of I-lysulfone resin (P1700: manufactured by Union Carbide) and 6 parts by weight of monochlorobenzene.
Parts by weight 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 was 12.5μ.

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

Further, the total surface potential of this photoreceptor after being left in a dark place for t-5 seconds was measured (dark decay V5).

Sensitivity was evaluated by measuring the exposure i (E1/21uX -5ee )' required for dark decay to decay to the postpotential v5't-v.

These results were less than the following.

Vo: -605 volts V5: -595 volts E1/2: 5.81ux11selc Examples 2 to 7 The compounds shown in Table 1 were used in place of the compound & (1) used in Example 1. 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 in Table 2.

Table 2 Examples Compound A V. (-V) V5 (-V)
E, /2 lux -5ec2 2 600 590
5.7 3 3 590 580 G, 2 4 4 600 590 6.0 5 5 610 600 6.4 6 6 620 610 6.6 7 7 615 605 6.3 Comparative Examples 1 to 6 Hydrazone used in Example 1 Photoreceptors were prepared in exactly the same manner except that the charge transporting substances shown in Table 3 were used in place of the compounds. The charging characteristics are shown in Table 4.

Table 3 Table 4 Comparative example Comparative charge Vcl (-V) V, (-V)
E, /21ux-sec transport material shop 1 1 590 565 7.
32 2 580 555 7.
13 3 590 570 7.
64 4 610 590 8.
65 5 595 565 7.
86 6 600 570 7.
As is clear from the results of Example 5 and Comparative Example, it can be seen that the thin layer type photoreceptor of the present invention has a much higher sensitivity than the Al-coated photoreceptor 6 of Comparative Example. Further, using the photoconductors of Examples 1 to 3 using a copying machine (NP-150z, manufactured by Canon Inc.), images were repeatedly produced 120,000 times. the result.

Good quality images were obtained for both photoreceptors even after repeating 20,000 times. 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 polyquinone-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 makes it possible to provide a laminated electrophotographic photoreceptor with high

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 halogen atom, a nitro group, an aryloxy group that may have a substituent, an alkoxy group, or a substituted 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 an alkyl group or an aryl group that may have a substituent.However, at least one of R_3 and R_4 is an aryl group.Also, R_3 and R_4 are Together, they may form a nitrogen-containing heterocycle. R_5, R_6, R_7 and R_8 each represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group which may have a substituent, an alkoxy group, an aryloxy group , representing an acyl group or an amino group.) An electrophotographic photoreceptor comprising a layer containing a hydrazone compound represented by: (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).