JPH09265194A - Electrophotographic photoreceptor and image forming method using the same - Google Patents

Abstract

(57) Abstract: ozone at a low cost, an electrophotographic photoreceptor is not affected by the oxidizing gas such as NO _X, and to provide an image forming method using the same. An intermediate layer on a conductive support, which is used in a process in which a time from charging to development is 0.5 seconds or more,
In a photoreceptor provided with a charge generation layer and a charge transport layer in this order, the oxygen gas permeability coefficient of the charge transport layer is 2.00 × 10 to
An electrophotographic photosensitive member characterized by being ¹¹ cm ³ · cm / cm ² · s · cmHg or less, and an image forming method using the same.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is ozone, in the presence of an oxidizing gas such as NO _X, in the process development is more than 0.5 seconds from the charging, superior less deterioration durability and repeated use The present invention relates to an electrophotographic photosensitive member having no image deterioration and an image forming method using the same.

[0002]

2. Description of the Related Art Conventionally, inorganic materials such as Se, CdS and ZnO have been used as photoconductive materials for electrophotographic photoreceptors, but they have problems of sensitivity, thermal stability, toxicity and the like. In recent years, electrophotographic photoreceptors using organic photoconductive materials have been actively developed, and in many copying machines and printers, electrophotographic photoreceptors using organic photoconductive materials have been installed. Has arrived.

Generally, the electrophotographic photosensitive member used in the Carlson process fulfills its function by being repeatedly subjected to the processes of charging-exposure-developing-transfer-discharging-cleaning, but these electrophotographic photosensitive members are always good. It is required to have the characteristic of being highly durable and capable of providing various images.

The same applies to an electrophotographic photosensitive member using an organic photoconductive material, which is required to have high durability and no image deterioration during repeated use. In addition, since the substance forming the photoconductor is an organic substance, ozone, N
Because it is considered deterioration by gas of O _X or the like, and also required improvement of gas resistance to these gases.

Fatigue caused by the oxidizing gas mainly causes a decrease in resistance of the photoconductor and an increase in dark decay. This increase in dark decay causes a decrease in charging potential in an actual machine.
This effect becomes remarkable when the time from charging to development is long, for example, when the time is 0.5 seconds or more as in the present invention, the density is lowered on the image and the background stain is generated at the time of reversal development.

On the other hand, in recent years, a copying machine using a process in which the time from charging to development is less than 0.5 seconds has been commercialized from the viewpoint of increasing the speed of the copying machine. However, a copying machine using these processes is expensive because it requires high speed and durability in all of paper feeding, images, fixing, etc., and the image quality is apt to deteriorate such as blurred characters. This becomes remarkable in a copying machine having a full-color image developing process using a plurality of developing devices (three or more). In this process, it is difficult to install a developing device in order to shorten the time from charging to development, and if the copying process speed is improved, the cost will be high and the characters will be blurred, color unevenness and resolution will be reduced. .

[0007]

OBJECTS OF THE INVENTION It is an object of the present invention is to provide an electrophotographic photosensitive member and an image forming method free from ozone, the effect of an oxidizing gas such as NO _X at a low cost. More specifically, NO _X, the image blur even when the image forming process was operated under ozone exposure environment, fogging, image density decrease without blurring letters, density uniformly, electrons good images are acquired It is to provide a photographic photoreceptor and an image forming method using the same.

[0008]

Means for Solving the Problems As a result of intensive studies made by the present inventors, in the process in which the time from charging to development is 0.5 seconds or more, the oxygen gas permeation coefficient of the charge transport layer is limited to limit the above problems. Therefore, the present invention has been completed by using this in a copying machine.

That is, the present invention is the following (1) to (4).

(1) In a photosensitive member comprising a conductive support, an intermediate layer, a charge generating layer, and a charge transporting layer provided in this order, which is used in a process in which the time from charging to development is 0.5 seconds or more, Oxygen gas permeability coefficient of the charge transport layer is 2.00 × 1
An electrophotographic photosensitive member characterized by having a content of 0 to ¹¹ cm ³ · cm / cm ² · s · cmHg or less.

(2) The photoconductor as described in (1) above, wherein the charge transport layer contains a biphenyl compound.

(3) The photoconductor as described in (1) above, wherein the charge transport layer contains the following compound (I).

[0013]

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(Wherein R ₁ represents a lower alkyl group,
R ₂ and R ₃ represent the same or different, substituted or unsubstituted methylene group or ethylene group, and Ar ₁ and Ar ₂ represent the same or different, substituted or unsubstituted aryl group. l is 0
4, m represents an integer of 0 to 2, and n represents an integer of 0 to 2, m + n is 2 or more, and l + m + n is an integer of 6 or less. Moreover, the unsubstituted site of the benzene ring represents a hydrogen atom. (4) Full-color image developing step by three or more developing devices arranged in the circumferential direction of the electrophotographic photosensitive member according to (1), and charging in the developing step in at least one or more developing devices. An image forming method characterized in that the time from developing to developing is 0.5 seconds or more.

Hereinafter, the present invention will be described in detail.

In the present invention, the time from charging to development being 0.5 seconds or more means that an electrophotographic photoreceptor is used and image formation including a series of steps including charging, exposure, development, transfer and cleaning. In the process, it means that the time from charging to development is 0.5 seconds or more.

The electroconductive support constituting the electrophotographic photosensitive member of the present invention has electroconductivity having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, aluminum, nickel, chromium, nichrome, copper, gold, silver. , Metal such as platinum, metal oxide such as tin oxide and indium oxide, coated on film or cylindrical plastic or paper by vapor deposition or sputtering, or plate of aluminum, aluminum alloy, nickel, stainless steel, etc. Also, after forming them into a raw tube by a method such as extrusion or drawing, a tube that has been surface-treated by cutting, superfinishing, polishing or the like can be used. In addition, JP-A-52-36016
The endless nickel belt and the endless stainless belt disclosed in the publication can also be used as the conductive support.

In addition to the above, a support obtained by dispersing conductive powder in a suitable binder resin and coating it on the support can also be used as the conductive support of the present invention.

Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, conductive titanium oxide, conductive tin oxide and ITO. Examples include metal oxide powder.

The binder resin used at the same time includes polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate. Copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal,
Polyvinyltoluene, poly-N-vinylcarbazole,
Examples thereof include thermoplastic resins such as acrylic resins, silicone resins, epoxy resins, melamine resins, urethane resins, phenol resins and alkyd resins, and thermosetting resins or photocurable resins. Such a conductive layer may be prepared by combining these conductive powders and a binder resin with a suitable solvent such as THF, MDC,
It can be provided by dispersing in MEK, toluene, etc. and applying.

Further, a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, or Teflon on a suitable cylindrical substrate is electrically conductive. Those provided with a layer can also be favorably used as the conductive support of the present invention.

Next, the charge generating layer and the charge transporting layer which are provided on the conductive support in the order of the charge generating layer and the charge transporting layer will be described.

The charge generating layer may be formed of only the charge generating substance or may be formed by dispersing the charge generating substance in the binder resin. Therefore, the charge generation layer is formed by dispersing these components in a suitable solvent by using a ball mill, an attritor, a sand mill, ultrasonic waves or the like, coating this on a conductive support or an intermediate layer, and drying. It

Examples of the charge generating substance used in the charge generating layer include phthalocyanine pigments such as titanyl phthalocyanine, vanadyl phthalocyanine, copper phthalocyanine, hydroxygallium phthalocyanine and metal-free phthalocyanine, monoazo pigments, bisazo pigments, asymmetric disazo pigments, trisazo pigments, Azo pigments such as tetraazo pigments, pyrrolopyrrole pigments, anthraquinone pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, squarium pigments, Se alloys, and other known materials can be used.

As the binder resin used in the charge generation layer, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polyvinylcarbazole, polyacrylamide, polyvinyl are used. Examples thereof include benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol and polyvinyl pyrrolidone.

The amount of the binder resin is appropriately 0 to 500 parts by weight, preferably 10 to 300 parts by weight, based on 100 parts by weight of the charge generating substance.

The thickness of the charge generation layer is 0.01-5 μm.
m, preferably 0.1 to 2 μm.

As the solvent used here, isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane,
Examples include toluene, xylene, ligroin, and the like.

As the coating method of the coating liquid, a dip coating method, spray coating, bead coating, nozzle coating, spinner coating, ring coating or the like can be used.

The charge-transporting layer can be formed by dissolving or dispersing the charge-transporting substance and the binder resin in a suitable solvent, coating the resultant on the charge-generating layer, and drying. Also,
If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.

The charge transport material includes a hole transport material and an electron transport material.

Examples of the electron transport material include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,
4,8-Trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene-4
-One, 1,3,7-trinitrodibenzothiophene-
Examples thereof include electron-accepting substances such as 5,5-dioxide and benzoquinone derivatives.

As the hole transport material, poly-N-vinylcarbazole and its derivative, poly-γ-carbazolylethylglutamate and its derivative, pyrene-formaldehyde condensate and its derivative, polyvinylpyrene, polyvinylphenanthrene, polysilane, Oxazole derivative, oxadiazole derivative, imidazole derivative, monoarylamine derivative, diarylamine derivative, triarylamine derivative, stilbene derivative,
α-phenylstilbene derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9
-Styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, and other known materials. These charge transport materials may be used alone or in combination of two or more.

As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, poly Vinyl acetate, polyvinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, Urethane resin,
Phenol resin, alkyd resin, JP-A-5-1582
Examples include thermoplastic or thermosetting resins such as various polycarbonate copolymers described in JP-A No. 50 and JP-A-6-51544.

The amount of the charge transport material is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin.
Parts by weight are appropriate.

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

As the solvent used here, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, dichloromethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.

In the present invention, a plasticizer in the charge transport layer,
A leveling agent and an antioxidant may be added.

As the plasticizer, those used as general plasticizers for resins such as cibutyl phthalate and dioctyl phthalate can be used as they are, and the amount thereof is 0 to 30 parts by weight with respect to 100 parts by weight of the binder resin. Some parts are appropriate.

As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain can be used, and the amount thereof is 100 parts by weight of the binder resin. On the other hand, 0 to 1 part by weight is suitable.

As the antioxidant, antioxidants such as hindered phenol compounds, sulfur compounds, phosphorus compounds, hindered amine compounds, pyridine derivatives, piperidine derivatives, morpholine derivatives and hydroquinone compounds can be used. The suitable amount is about 0 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

Further, in the electrophotographic photosensitive member, it is possible to provide an intermediate layer between the conductive support and the charge generating layer.

As the intermediate layer, a resin containing a resin as a main component or a resin containing a fine powder pigment such as a metal oxide can be used. Considering that the photosensitive layer is coated with a solvent on the intermediate layer, it is desirable that these resins have a high solvent resistance to general organic solvents. Examples of such resins include polyvinyl alcohol, casein, water-soluble resins such as sodium polyacrylate, copolymer nylon, alcohol-soluble resins such as methoxymethylated nylon, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-anhydrous. Maleic acid copolymer, ethylene-based resin such as ethylene-vinyl acetate-methacrylic acid copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-based resin such as vinyl chloride-vinyl acetate-maleic anhydride copolymer, Curable resins that form a three-dimensional network structure such as cellulose derivative resins, polyurethane, melamine resins, phenol resins, alkyd-melamine resins, acrylic-melamine resins, silicone resins, silicone-alkyd resins, epoxy resins, polyisocyanate compounds, etc. Can be mentioned.

Fine powder pigments of metal oxides such as titanium oxide, aluminum oxide, silica, zirconium oxide, tin oxide and indium oxide may be added to the intermediate layer in order to prevent moire and reduce residual potential. .

Further, as the intermediate layer of the present invention, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, a titanyl chelate compound, a zirconium chelate compound, a titanyl alkoxide compound, and an organic titanyl compound can also be used.

These intermediate layers can be formed by coating the resin by dissolving the resin with a suitable solvent or dispersing the fine powder of the metal oxide in the resin.

As the solvent used here, isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane,
Examples include toluene, xylene, ligroin, and the like.

As the coating method of the coating liquid, a dip coating method, a spray coating method, a bead coating method, a nozzle coating method, a spinner coating method, a ring coating method and the like can be used.

In addition, the intermediate layer of the present invention comprises Al ₂ O ₃
Provided by anodic oxidation, organic substances such as polyparaxylylene, SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂
Those provided with an inorganic substance such as by a vacuum thin film forming method can also be favorably used.

A suitable thickness of the intermediate layer is 0 to 10 μm.

The biphenyl compounds used in the present invention are shown below, but the present invention is not limited to these specific examples.

Biphenyl, 2-methylbiphenyl, 3-
Methylbiphenyl, 4-methylbiphenyl, 2-ethylbiphenyl, 3-ethylbiphenyl, 2,3-dimethylbiphenyl, 2,4-dimethylbiphenyl, 2,5-dimethylbiphenyl, 2,6-dimethylbiphenyl, 2,
2'-dimethylbiphenyl, 2,3'-dimethylbiphenyl, 3,5-dimethylbiphenyl, 3,3'-dimethylbiphenyl, 3,4'-dimethylbiphenyl, 2-propylbiphenyl, 4-propylbiphenyl, 2-isopropyl Biphenyl, 3-isopropyl biphenyl, 4
-Isopropylbiphenyl, 2-ethyl-5-methylbiphenyl, 2,4,6-trimethylbiphenyl, 2,
4,3′-trimethylbiphenyl, 2,5,3′-trimethylbiphenyl, 2,5,4′-trimethylbiphenyl, 2,6,2′-trimethylbiphenyl, 3,5,5
4'-trimethylbiphenyl, 2-butylbiphenyl,
4-butylbiphenyl, 2-sec-butylbiphenyl, 4-sec-butylbiphenyl, 2-isobutylbiphenyl, 2-tert-butylbiphenyl, 3-te
rt-butylbiphenyl, 4-tert-butylbiphenyl, 2,2'-diethylbiphenyl, 3,3'-diethylbiphenyl, 4,4'-diethylbiphenyl, 2,
3,2 ', 3'-tetramethylbiphenyl, 2,6
2 ', 6'-tetramethylbiphenyl, 3,4,3',
4'-tetramethylbiphenyl, 3,5,3 ', 5'-
Tetramethylbiphenyl, 4-hexylbiphenyl,
4,4'-dipropylbiphenyl, 2,2'-diisopropylbiphenyl, 4,4'-diisopropylbiphenyl, 2,4,6,2 ', 4', 6'-hexamethylbiphenyl, 4,4'-dibutyl Biphenyl, 2,5-di-
tert-butylbiphenyl, 2,2'-di-tert
-Butyl-biphenyl, 4,4'-di-tert-butyl-biphenyl, 2,3,5,6,2 ', 3', 5 ',
6'-octamethylbiphenyl, 4,4'-di-ter
t-pentylbiphenyl, hydrogenated terphenyl, o-terphenyl, m-terphenyl, p-benzylbiphenyl, 5'-methyl-m-terphenyl, 4-phenylbibenzyl, 4'5'-dimethyl-m- Terphenyl,
4 ', 6'-dimethyl-m-terphenyl, 1-ethyl-4-benzylbiphenyl, 4-propyl-m-terphenyl, 3', 4 ', 6'-trimethyl-o-terphenyl, 2', 4 ', 5'-trimethyl-m-terphenyl, 2', 4 ', 6'-trimethyl-m-terphenyl, 4-ethyl-4'-phenethyl-biphenyl, 3-
Pentyl-m-terphenyl, 2-methoxybiphenyl, 2-ethoxybiphenyl, 2-propoxybiphenyl, 2-phenoxybiphenyl, 2-benzyloxybiphenyl, 3-methoxybiphenyl, 4-methoxybiphenyl, 4-ethoxybiphenyl, 4- Propoxybiphenyl, 4-isopropoxybiphenyl, 4-butoxybiphenyl, 4-pentyloxybiphenyl, 4-phenoxybiphenyl, 4-m-triloxybiphenyl, 4-p
-Triloxybiphenyl, 4-benzyloxybiphenyl, 4'-methoxy-3-methylbiphenyl, 4-methoxy-4'-methyl-biphenyl, 4-cyclohexyloxymethylbiphenyl, 2-ethyl-5-methoxybiphenyl, 4 ' -Methoxy-3,4-dimethylbiphenyl, 3'-methoxy-o-terphenyl, 4'-methoxy-o-terphenyl, 5-benzyl-2-methoxy-
Biphenyl, 4-benzyl-4'-methoxybiphenyl, 4- [α-methoxybenzyl] biphenyl and the like can be mentioned.

In the compound of the general formula (I) used in the present invention, in the formula, the lower alkyl group for R ₁ is
Examples thereof include a methyl group and an ethyl group, and a lower alkyl group having 1 to 6 carbon atoms is preferable. R ₂ and R ₃ are methylene groups,
An ethylene group, and the substituent thereof is an alkyl group such as a methyl group or an ethyl group, an aralkyl group such as a benzyl group,
An aryl group such as a phenyl group may be mentioned, and R ₂ and R ₃ may be the same or different. Further, examples of the aryl group of Ar ₁ and Ar ₂ include a phenyl group, a biphenyl group, a naphthyl group, and the like, and the substituent thereof is an alkyl group such as a methyl group, an ethyl group, and a propyl group, and an aralkyl group such as a benzyl group. And Ar ₁ and Ar ₂ may be the same or different.

Specific examples of the compound represented by the above general formula (I) are shown below, but the present invention is not limited to these specific examples.

[0055]

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[0056]

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[0057]

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[0058]

[Chemical 6]

[0059]

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[0060]

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[0061]

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[0062]

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[0063]

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[0064]

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[0065]

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[0066]

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[0067]

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The compound represented by the above general formula (I) of the present invention is prepared by, for example, dissolving a corresponding chloroalkyl derivative and a hydrocarbon in nitromethane, and stirring the mixture under a nitrogen stream to obtain ZnC.
It can be obtained by adding a catalyst such as l ₂ or ZnCl ₃ and reacting at a constant temperature.

The reason why the biphenyl compound of the present invention and the compound represented by the general formula (I) are effective in improving gas resistance is not clear, but the biphenyl compound and the general formula (I) By containing the compound represented by the formula (4) in the photoconductor, it is possible to reduce the minute voids present in the photoconductor and to reduce the gas permeability to gases such as ozone and NO _x. Conceivable. Further, the same reason can be considered for the reason why it is effective in improving potential fluctuation and image deterioration during repeated use, but in addition, by improving the compatibility between the constituent substances used in the photoconductor, It is considered that this is also due to the fact that it has an effect of suppressing the formation of agglomerates that cause defects and concealing image defect sites.

Next, the case where the time from charging to development is 0.5 seconds or more according to the present invention will be described.

The image forming process using the electrophotographic photosensitive member according to the present invention is not limited to the color process, but is particularly remarkable in the color process. As a typical example, the case of using the color process will be described below.

As a color process in electrophotography, there are "electrophotographic process technology" (Trikeps P. 23).
7-P. 241) as described in CC
D, a process of using a semiconductor laser for writing and using a rotary type developing device to superimpose one color on the transfer paper,
For example, a process in which a photoconductor and a transfer member are arranged side by side using an analog exposure system, a process in which a belt photoconductor is used, and a toner image is superposed on a transfer paper by switchback can be cited. In addition, after the color toner images are superposed on the transfer body, the process of collectively transferring them on the transfer paper, the process of superposing the color toner images on the photoconductor and then collectively transferring them on the transfer paper, and the process units are arranged in parallel, Process of sequentially transferring on transfer paper sent by transfer belt, process unit arranged in parallel and superposing on the transfer belt one after another, transfer to transfer paper, charger around photoconductor,
Examples include a process in which a plurality of sets of an image exposure system and a developing device are arranged, toner images are superposed on a photoconductor, and then transferred to a transfer paper.

In these processes, since there are a plurality of developing units, there are problems that the monochrome process does not have. That is, for example, in the image forming method of (4) above, in the case of a process having one photoconductor and one charger and a plurality of developing units, the time from charging to developing differs depending on the position of the developing unit. Cause

On the other hand, during the operation of the copying machine, there is a risk of being affected by oxidizing gas such as ozone or NO _x , and more specifically, it has a great influence on the process from charging to development.

Ozone may be generated from the corona charger in the copying machine, and NO _x gas may be generated from the corona charger in the copying machine, but kerosene, light oil, heavy oil, etc. It is also generated when burning petroleum-based fuels. For example, when a heating device that burns kerosene in a closed room is used, the NO _x concentration rises when ventilation is insufficient, and when the intake and exhaust are insufficient even in the copying machine. _X concentration increases.

From charging to development in the above copying process,
To reduce the effect of the above gases on the process,
(1) suppressing the gas concentration low, (2) shortening the time from charging to development, (3) in the case of a laminate type photoreceptor having a charge generation layer and a charge transport layer on a support, ozone in the charge transport layer on the surface, to have a gas barrier property and the like for the gas to at least a charge transport layer in order to suppress the permeation and diffusion of the NO _X such oxidizing gas is considered as a countermeasure.

However, there is a limit to suppressing the gas concentration in the above (1). Also, there is a limit to the reduction of the time from charging to development in (2). That is, in the electrophotographic color process, especially in the process in which each of the above-mentioned photoconductor and charger is provided and a plurality of developing units are provided, the time from charging to developing differs depending on each developing unit. There is a limit to shortening the time from charging to development for the developing unit.

Therefore, as in the present invention, even if the time from the charging to the development is longer than a certain length, the cost is high, the image is free of character blurring, and the density is high.
In particular, a full color image can be provided.

Therefore, in the present invention, in addition to the above (2), the measure for gas permeability of (3) is combined. Specifically, in order to provide the charge transport layer with an oxidizing gas barrier property such as ozone and NO _x , the charge transport oxygen gas permeability coefficient is 2.00 × 10 to ¹¹ cm ³ · cm / cm ² · s.
A good image is formed by using an electrophotographic photosensitive member having a cmHg or less.

[0080]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to Examples and the like.

Example 1 40 parts by weight of titanium oxide (TM-1, manufactured by Fuji Titanium Industry Co., Ltd.), alkyd resin (Beckolite M6401-50-
S (solid content 50%): 6 parts by weight of Dainippon Ink and Chemicals, melamine resin (G821-60 (solid content 60%):
A mixture of 4 parts by weight of Dainippon Ink and Chemicals, Inc. and 50 parts by weight of methyl ethyl ketone was dispersed in a ball mill for 78 hours to prepare a coating liquid for the intermediate layer. This is total length 346m
m, inner diameter 114 mm, outer diameter 120 mm, dip-coated on an aluminum drum, and dried at 130 ° C. for 20 minutes to obtain a film thickness of 3.5.
A μm intermediate layer was prepared.

Next, 10 parts by weight of the trisazo pigment represented by the following structural formula (II) was added to 115 parts by weight of cyclohexanone and dispersed for 2 hours, and then polybutyral (BM
-S: Sekisui Chemical Co., Ltd.) 4 parts by weight of 322 parts by weight of cyclohexanone and 229 parts by weight of methyl ethyl ketone were added and dissolved, and the mixture was stirred to prepare a coating liquid for the charge generation layer. This is applied onto the intermediate layer by dip coating,
It was dried at 0 ° C. for 20 minutes to form a charge generation layer having a film thickness of 0.2 μm.

Next, 6.2 parts by weight of the charge transport material represented by the following structural formula (III), 0.8 part by weight of the bisbenzylbenzene derivative represented by the following structural formula (IV), and polycarbonate (TS-2050). (Viscosity average molecular weight 50,000): Teijin Chemicals Ltd.) 10 parts by weight, 2,5-di-tert-butylhydroquinone 0.014 parts by weight, silicone oil (KF)
-50: manufactured by Shin-Etsu Chemical Co., Ltd.) 0.002 parts by weight was dissolved in 117 parts by weight of dichloromethane to prepare a coating liquid for the charge transport layer. This is applied onto the charge generation layer by dip coating,
By drying at 0 ° C. for 20 minutes, a charge transport layer having a film thickness of 28 μm was formed to obtain an electrophotographic photoreceptor.

[0084]

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<Measurement of Oxygen Permeability Coefficient of Charge Transport Layer> The coating liquid for charge transport layer used in the preparation of the photosensitive drum was 100
Blade coating on PET with a thickness of μm,
Minute, then dry at 110 ° C for 20 minutes, and after cooling P
The charge transport layer resin film was peeled off from ET to obtain a 28 μm film.

Then, using oxygen equivalent to JIS K 1101, measurement temperature: 23 ± 0.5 ° C., test pressure: 760
mmHg, transmission area: 38.46 cm ² (φ70 mm)
Under the measurement conditions described above, a differential pressure detection type gas permeation test according to JIS K 7126 was carried out using a measuring machine: Model M-C3 manufactured by Toyo Seiki Co., Ltd. to obtain an oxygen gas permeation coefficient.

<Image evaluation in which the time from charging to development is regulated in an oxidizing gas (NO _x ) atmosphere> The electrophotographic photosensitive drum is set on a pre-tail 550 (manufactured by Ricoh Co., Ltd.) and a blue heater ( Operate the Dainichi blue heater model FM152), and in the environment where the NO _x concentration near the pre-tail 550, especially near the intake port is set to 5 ppm, the pre-tail is set to 1.0 second from the charging to the development of the yellow part. Operate A3 paper (RICOPY PPC paper TYPE6200A3)
Then, 99 full-color continuous copies were made, and the image condition was visually confirmed.

Examples 2 to 4 In preparing the coating liquid for the charge transport layer in Example 1, the above (IV)
The dibenzylbenzene derivative represented by
Preparation of electrophotographic photosensitive member except that 5, 1.0, 2.0 parts by weight and the charge transporting material represented by the formula (III) were prepared as 6.5, 6.0, 5.0 parts by weight, respectively. In the same manner as in Example 1, image evaluation in which the time from charging to development was defined in a NO _x atmosphere and oxygen gas permeation coefficient of the charge transport layer resin film were measured.

Examples 5, 6 Preparation of a photoconductor was carried out in the same manner as in Example 1 except that the pre-tail 550 and the time from charging to development during operation were 0.5 seconds and 1.5 seconds, respectively. , Image evaluation in which the time from charging to development in a NO _x atmosphere was specified, and oxygen gas permeability coefficient of the charge transport layer was measured.

Example 7 Except that the bisbenzylbenzene derivative represented by the formula (IV) was changed to the biphenyl compound represented by the following structural formula (V) when the coating liquid for the charge transport layer was prepared in Example 1. The production of the electrophotographic photosensitive member, the image evaluation in which the time from charging to development in the NO _X atmosphere was regulated, and the oxygen gas permeation coefficient of the charge transport layer were measured in the same manner as in Example 1.

[0091]

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Example 8 In preparing the coating liquid for the charge transport layer in Example 1, the bisbenzylbenzene derivative represented by the formula (IV) was replaced with the biphenyl compound represented by the structural formula (V) to obtain 1.5. The amount of the charge transport material represented by the formula (III) is 7.0 parts by weight.
Production of the electrophotographic photosensitive member, image evaluation in which the time from charging to development in a NO _x atmosphere was regulated, and oxygen gas permeability coefficient of the charge transport layer were measured in the same manner as in Example 1 except that the weight part was used.

Examples 9 to 11 In preparing the coating liquid for the charge transport layer in Example 1, the bisbenzylbenzene derivative represented by the formula (IV) was converted into the following structural formula (V
Preparation of an electrophotographic photoreceptor, oxygen in the charge transport layer except that the bisbenzylbenzene derivative shown in I) was changed to 1.0 part by weight and the charge transport material represented by the formula (III) was changed to 6.0 parts by weight. The gas permeation coefficient was measured in the same manner as in Example 1, and the image evaluation in which the time from charging to development in the NO _x atmosphere was specified was in Examples 9, 10 and 11, 0.5 seconds and 1.0 seconds, respectively. , 1.5 seconds.

[0094]

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Examples 12 to 14 In preparing the coating liquid for the charge transport layer in Examples 9 to 11, the bisbenzylbenzene derivative represented by the formula (VI) was changed to the bisbenzylbenzene derivative represented by the following structural formula (VII). Except for changing the conditions, the production of the electrophotographic photosensitive member, the image evaluation in which the time from charging to development in the NO _X atmosphere was regulated, and the oxygen gas permeation coefficient of the charge transport layer were measured in the same manner as in Examples 9 to 11.

[0096]

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Examples 15 to 17 In preparing the coating liquid for the charge transport layer in Examples 9 to 11, the bisbenzylbenzene derivative represented by the formula (VI) was changed to the bisbenzylbenzene derivative represented by the following structural formula (VIII). Except for changing the conditions, the production of the electrophotographic photosensitive member, the image evaluation in which the time from charging to development in the NO _X atmosphere was regulated, and the oxygen gas permeation coefficient of the charge transport layer were measured in the same manner as in Examples 9 to 11.

[0098]

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Examples 18 to 20 In preparing the coating solutions for the charge transport layer in Examples 9 to 11, the bisbenzylbenzene derivative represented by the formula (VI) was changed to the biphenyl compound represented by the following structural formula (IX). Other than the above, the production of the electrophotographic photosensitive member, the image evaluation in which the time from charging to development in the NO _x atmosphere was regulated, and the oxygen gas permeation coefficient of the charge transport layer were measured in the same manner as in Examples 10 to 12.

[0100]

[Chemical 21]

Comparative Example 1 In Example 1, the time from charging to development was 0.3 seconds, and when the coating solution for the charge transport layer was prepared, the bisbenzylbenzene derivative represented by the above (IV) was not added. An electrophotographic photosensitive member was prepared except that the charge-transporting substance represented by (III) was prepared in an amount of 0.7 parts by weight, image evaluation in which the time from charging to development in a NO _x atmosphere was specified, and oxygen-permeation of charge-transporting layer. Coefficient measurement was performed in the same manner as in Example 1.

Comparative Examples 2 and 3 Except that in Comparative Example 1, the pretail 550 and the time from charging to development during operation were 0.5 seconds and 1.5 seconds, respectively.
In the same manner as in Comparative Example 1, an electrophotographic photosensitive member was prepared, image evaluation was performed in which the time from charging to development in a NO _x atmosphere was specified, and oxygen gas permeability coefficient of the charge transport layer was measured.

Comparative Example 4 In preparing the coating liquid for the charge transport layer in Example 1, the above (I
V) is added to the charge transporting material represented by the formula (III) in 7.0 parts by weight without adding the bisbenzylbenzene derivative represented by the formula (V), and polycarbonate is TS-20 manufactured by Teijin Chemicals Ltd.
Similarly Preparation of photoreceptor except for changing the Teijin Kasei Co., Ltd. pearlite K-1300 from 50 to Example 1, image evaluation which defines the time from the charging under NO _X atmosphere until development, the charge transport layer oxygen gas The transmission coefficient was measured.

Comparative Examples 5 and 6 Photosensitive members were prepared in the same manner as in Example 1 except that the time from charging to development when the pre-tail 550 was operated was 0.2 seconds and 0.4 seconds, respectively. Image evaluation in which the time from charging to development in a NO _x atmosphere was specified, and the oxygen gas permeability coefficient of the charge transport layer was measured.

Table 1 shows a list of the operating conditions of the examples and comparative examples carried out as described above. The oxygen gas permeation coefficient of each charge transport layer resin film and the time from charging to development in a NO _x atmosphere are specified. Table 2 shows the image evaluation results.

In Table 1, the time from charging to development is the time from charging to yellow (Y) development.

[0107]

[Table 1]

[0108]

[Table 2]

[0109]

As described above, according to the present invention, a good image can be obtained, gas resistance is excellent, durability by repeated use is excellent, and image density reduction and background fog are caused even after repeated use. It is a high-performance electrophotographic photosensitive member having no image defects such as the above and an image forming method using the same, and is extremely excellent in practical value.

Claims (4)

[Claims] 1. An intermediate layer on a conductive support, which is used in a process in which a time from charging to development is 0.5 seconds or more,
In a photoreceptor provided with a charge generation layer and a charge transport layer in this order, the oxygen gas permeability coefficient of the charge transport layer is 2.00 × 10 to
An electrophotographic photosensitive member characterized by having a density of ¹¹ cm ³ · cm / cm ² · s · cmHg or less. 2. The photoreceptor according to claim 1, wherein the charge transport layer contains a biphenyl compound. 3. The photoconductor according to claim 1, wherein the charge transport layer contains the following compound (I). Embedded image (In the formula, R ₁ represents a lower alkyl group, R ₂ and R ₃ represent the same or different, substituted or unsubstituted methylene groups or ethylene groups, and Ar ₁ and Ar ₂ are the same or different, substituted or unsubstituted Represents an aryl group of 1 is 0 to 4, m is 0
2, n represents an integer of 0 to 2, m + n is 2 or more, l +
m + n is an integer of 6 or less. Moreover, the unsubstituted site of the benzene ring represents a hydrogen atom. ) 4. An electrophotographic photosensitive member according to claim 1, comprising a full-color image developing step by three or more developing devices arranged in the circumferential direction, and charging in the developing step in at least one or more developing devices. An image forming method characterized in that the time from developing to developing is 0.5 seconds or more.