JPH01287570A - Electrophotographic sensitive body and image forming method - Google Patents

Abstract

PURPOSE:To improve sensitivity and chargeability of an electrophotographic sensitive body and to stabilize photosensitivity and charge potential against variation of environment, by incorporating a charge generating pigment having hole transfer characteristic and a specified cyanovinyl compd. into a binder resin in a charge generating layer. CONSTITUTION:In an electrophotographic sensitive body comprising a successively laminated charge generating layer and charge transfer layer on a base body 3, a charge generating pigment having hole transfer characteristic and a cyanovinyl compd. expressed by the formula I are incorporated into a binder resin in the charge generating layer 1. In the formula I, A is an aromatic group or a heterocyclic group, both may be substituted; X is a hydrogen (H), atom, or a halogen atom; R1 is a cyano group, alkoxycarbonyl group, etc.; R2 is an H atom, alkyl group, or cyano group; n is zero of 1; m is 1 or 2. Thus, an electrophotographic sensitive body having good chargeability, high photosensitivity, stable photosensitivity and charge potential against variation of environment is obtd. wherein the potential of the exposed part and the unexposed part are stable even after copying many sheets of the electrophotographic sensitive body.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor and an image forming method using the same, and in particular, to an electrophotographic photoreceptor and an image forming method using the same. The present invention relates to an electrophotographic photoreceptor.

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

In recent years, to solve the shortcomings of inorganic photoconductive materials. Research into electrophotographic photoreceptors using organic photoconductive materials has been actively progressing, and electrophotographic photoreceptors using charge transfer complexes consisting of polyvinylcarbazole and 2,4,7-dolinitrofluorenone, pyrylium salts and alkylidene diamide Electrophotographic photoreceptors using eutectic complexes with arylene are known.

Recently, electrophotographic photoreceptors have been proposed in which the functions of absorbing light and generating electric charges and transporting the generated electric charges are divided into separate materials. A laminated type containing the same material has been proposed. (For example, see JP-A-58-16247.) Furthermore, in recent years, it has been proposed to include a cyanovinyl compound together with an electron donating charge transfer substance in the charge transport layer to prevent an increase in residual potential. .

(Japanese Unexamined Patent Publication No. 58-7643 @ Publication) Problems to be Solved by the Invention However, electrophotographic photoreceptors using these organic photoconductive materials have low photosensitivity and are not yet sufficient as photoreceptors. There wasn't. Further, a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are functionally separated has not yet been sufficiently satisfactory for practical use.

That is, even in the conventionally proposed multilayer electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated on a support, the photosensitivity is still insufficient, and the photosensitivity and charging potential are insufficient. There have been problems in that the potential changes greatly due to environmental changes and that potential cycle fluctuations between exposed and non-exposed areas are large.

Such problems can also be seen in the normal process of developing unexposed areas on a photoreceptor with toner and then transferring the toner image to a transfer material such as paper, but this is especially true when the photoreceptor is uniformly negative. This is particularly noticeable in image forming methods that include the steps of charging to form an electrostatic latent image, developing to form a toner image, and applying positive charges during transfer. In other words, the electric potential of the exposed and non-exposed areas of the photoreceptor causes wide cyclical fluctuations, resulting in a marked difference in the density of the transferred image between the initial image and the image after multiple copies, or If fog occurs on the image, or if you change the size of the transfer paper to a larger size after copying a large number of copies, the transfer density may be high on the portion of the transfer paper that corresponds to the width difference of the transfer paper. However, there were some disadvantages such as fogging and fogging.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to solve the above-mentioned problems in the conventional technology.

That is, the object of the present invention is to have good chargeability, high photosensitivity,
An object of the present invention is to provide an electrophotographic photoreceptor whose photosensitivity and charging potential are stable against environmental changes, and whose potentials in exposed and non-exposed areas are stable even when a large number of copies are made.

Another object of the present invention is to uniformly charge a photoreceptor negatively to form an electrostatic latent image, and then apply negatively charged toner to a low potential portion of the electrostatic latent image to form a toner image. Another object of the present invention is to provide an electrophotographic photoreceptor suitable for use in an image forming method that includes a step of performing transfer by applying a charge of a certain polarity.

Still another object of the present invention is to uniformly charge a photoreceptor negatively;
After forming an electrostatic latent image, negatively charged toner is attached to the low potential part of the electrostatic latent image to form a toner image, and the process is transferred by applying a charge of a certain polarity. It is an object of the present invention to provide an electrophotographic image forming method that, when applied to a photographic process, can obtain an image with uniform image density without causing large cyclical fluctuations in the potential of exposed and non-exposed areas.

Means and Effects for Solving the Problems The above-mentioned object of the present invention is to provide an electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated on a support, in which the charge generation layer is formed in a binder resin. This can be achieved by using a material containing a pore-transporting charge-generating pigment and a cyanovinyl compound represented by the following general formula (1).

That is, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated on a support, in which the charge generation layer has hole transporting charge generation in a binder resin. It is characterized by containing a pigment and a cyanovinyl compound represented by the following general formula (I).

(In the formula, A represents an optionally substituted aromatic group or an optionally substituted heterocyclic group, X represents a hydrogen atom or a halogen atom, and R1 represents a cyano group (however, when n=1 may be an aryl group), an alkoxycarbonyl group, an aryloxycarbonyl group, an aminocarbonyl group, an acyl group, an optionally substituted benzoyl group, or an optionally substituted phenyl group, and R2 is a hydrogen atom or an alkyl group. or diazi group, n represents O or 1, m is 1
or 2) The electrophotographic photoreceptor of the present invention will be described below.

1 to 4 are schematic cross-sectional views showing the laminated structure of the electrophotographic photoreceptor of the present invention. In FIG. 1, a charge generation layer 1 and a charge transport layer 2 are sequentially provided on a conductive support 3. In FIG. 2, the conductive support 3
An undercoat layer 4 is provided between the charge generating layer 1 and the charge generating layer 1 . Third
In the figure, a protective layer 5 is provided on the surface of the charge transport layer 3, and in FIG. 4, a subbing layer 4 is provided between the conductive support 3 and the charge generation layer 1, and the charge transport layer A protective layer 5 is provided on the surface of 2.

Next, each layer constituting the electrophotographic photoreceptor of the present invention will be explained.

Conductive supports include aluminum, copper, iron, zinc,
Drums of metal such as nickel, and aluminum, copper, gold, silver, platinum, on sheets, paper, plastic or glass.
Deposit metals such as palladium, titanium, nickel-chromium, stainless steel, copper-indium, conductive metal compounds such as indium oxide and tin oxide, laminate metal foil, or deposit carbon black, oxide, etc. Known materials such as drum-shaped, sheet-shaped, plate-shaped materials can be used, which are conductive-treated by dispersing indium, wrinkled tin-antimony oxide powder, metal powder, etc. in a binder resin and applying the coating.

Further, if necessary, the surface of the conductive support can be subjected to various treatments as long as the image quality is not affected. for example,
For the purpose of preventing interference fringes that occur when the surface is subjected to oxidation treatment, chemical treatment, coloring treatment, or when coherent light such as laser light is used for image exposure, the surface of the conductive support is coated with
A light absorption layer may be provided or a light scattering treatment may be performed. Light scattering treatment methods include sandblasting, liquid honing, magnetic polishing, puff polishing, belt sanding,
Brush polishing method, steel wool method, etching method, alkali etching method, electrochemical etching method, etc. can be used.

Further, a subbing layer may be further provided between the conductive support and the charge generation layer. This subbing layer prevents the injection of charge from the conductive support to the photosensitive layer when the photosensitive layer consisting of a laminated structure is charged, and also holds the photosensitive layer adhesively aligned with the conductive support. Depending on the case, the conductive support acts as a contact layer to prevent reflection of light.

Binder resins used for this undercoat layer include polyethylene, polypropylene, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate, polyurethane, polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, Vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, water-soluble polyester, nitrocellulose, casein,
Known resins such as pyratine can be used.

The thickness of the subbing layer is suitably 0.01 to 10 .mu.m, preferably 0.05 to 3 .mu.m. Furthermore, coating methods used when providing an undercoat layer include blade coating method, Mayer bar coating method, spray coating method,
Conventional methods such as dip coating, bead coating, air knife coating, curtain coating, etc. can be used.

In the present invention, the charge-generating layer constituting the photosensitive layer on the conductive support contains a hole-transporting charge-generating pigment, a cyanovinyl compound represented by the above general formula (I>), and a binder resin.

The charge generating pigment used with the cyanovinyl compound is
It is necessary that the material itself has hole transport properties. To determine whether a charge-generating pigment has hole-transporting properties, the pigment is vapor-deposited or dispersed in a resin at a high concentration and applied to a substrate to create a multilayer, which is then positively or negatively charged. It is sufficient to use a determination method that measures optical attenuation. In the present invention, “
The term "hole-transporting charge-generating pigment" refers to a pigment that exhibits greater optical attenuation when positively charged than when negatively charged in the above determination method.

In the present invention, the hole-transporting charge-generating pigment includes:
Squareylium pigments, phthalocyanine pigments, perylene pigments, etc. can be used.

The square aryllium pigment has the following general formula % formula % [wherein R8 and R9 are a hydrogen atom, a hydroxyl group,
Fluorine atom, alkyl group, -NR16R1□ (where R
16 and R17 each represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkylcarbonyl group, or an arylcarbonyl group), an alkoxy group, or an aryloxy group, and R10 is -NR18R19 (here, R18 and R19 are , each representing an alkyl group, an aryl group, or an aralkyl group), and R11 to R1
4 each represents one hydrogen atom, an alkyl group, an aryl group,
-CONHR2゜ (here, R20 represents an alkyl group, aryl group, or aralkyl group), a halogen atom, an alkoxy group, or an aryloxy group, R15 represents an alkyl group, an aryl group, or an aralkyl group, and Z is 〉CR
21R22, -5-1-CR21-CR22- (herein, R21 and R22 each represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group); For example, the following can be exemplified.

■zu 〇- m-410- CH30CH3 As a phthalocyanine pigment, the following general formula % formula % (wherein, R23 is a hydrogen atom, an alkyl group, an aryl group,
represents an aralkyl group, a halogen atom, a cyano group, or a nitro group, M is two hydrogen atoms, or Cu, Ni
, Co, Fe, Mn, Cr, Ti, Ru, Pd, I
n, Sn, Sb, Zn, MQ, Ga, ae, AS,
represents a metal atom selected from si, HCI, T;, v, u, and Pd, D and F each represent a halogen atom or an oxygen atom, and X and y each represent O or 1.
shows. However, when M is a divalent metal atom, both X and y represent O, and when M is a trivalent metal atom, X
is 1, y represents O, and when M is a tetravalent metal atom, X
and y both represent 1, when M is V, A is an oxygen atom, X is 1, y represents O, and when M is V, A and B
is an oxygen atom, and X and y both represent 1) Specifically, for example, metal-free phthalocyanine, copper phthalocyanine, vanadyl phthalocyanine, titanyl phthalocyanine, aluminum phthalocyanine, gallium phthalocyanine, indium phthalocyanine, thallium phthalocyanine, silicon phthalocyanine, germanium Examples include phthalocyanine, tin phthalocyanine, lead phthalocyanine, and halides of the above phthalocyanines.

Further, as perylene pigments, for example, the following general formula (V
) can be mentioned.

(In the formula, R24 is an optionally substituted alkyl group,
(representing an aryl group or an aralkyl group), specifically, the following can be exemplified.

(J IJ On the other hand, as the cyanovinyl compound represented by the above general formula (I>), a compound represented by the following general formula (II) can be preferably used.

(In the formula, R2 represents a hydrogen atom, an alkyl group, or a cyano group, and R to R7 each represent a hydrogen atom, an alkyl group,
represents an alkoxy group, an aryloxy group, an aryl group, an alkenyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group, a halogen atom, a cyano group, or a nitro group, or two adjacent to each other Indicates the atomic group necessary for bonding together to form an aromatic ring or a heterocycle. ) Specific examples of the cyanovinyl compound represented by the above general formula (I) include the following.

Knee 7 I-8 Knee 1
8 ρ distribution U~ Knee wing ON Knee 46 ■-47 Knee 50 Knee 51 ■-52 ■-54 ■-56 o2 ■-φ ■-Knee l-85 Knee 67 I-brocade ■-〇9 Knee 10 Knee 11 Above Binding resins for the hole-transporting charge-generating pigment and the above cyanovinyl compound include polystyrene, silicone resin, polycarbonate resin, acrylic resin, methacrylic resin, polyester, vinyl resin, cellulose, alkyd resin, etc. Any conventionally known material can be used.

In the charge generation layer of the present invention, the cyanovinyl compound has a ratio of 0.01 to
It is contained in an amount of 2 equivalents, preferably 0.1 to 1 equivalent. If the amount of the cyanovinyl compound is less than o, oi, the effect on the above-mentioned increase in photosensitivity and reduction of environmental fluctuations and repeated fluctuations in the potential of exposed/unexposed areas will be reduced, and if the amount is higher than 2 equivalents, In this case, the dark decay greatly increases, the charging potential decreases, and in an electrophotographic process in which toner is formed in non-exposed areas, the background area tends to be fogged, so the above range is preferable.

Further, the hole transporting charge generating pigment is preferably blended in an amount of 0.1 to 10 parts by weight per 1 part by weight of the binder resin.

Various methods can be used to incorporate the hole-transporting charge-generating pigment and the cyanovinyl compound into the charge-generating layer. For example, it can be contained in the following manner. ■Add a hole-transporting charge-generating pigment and a cyanovinyl compound together into a binder resin solvent solution and disperse them. Dispersion methods include ball mill dispersion, attritor dispersion, sand mill dispersion, and ultrasonic dispersion. Any commonly employed method can be used. (2) First, a hole-transporting charge-generating pigment is dispersed in a solvent solution of a binder resin, and a cyanovinyl compound is added to the resulting dispersion. (2) A hole-transporting charge-generating pigment is previously treated with a solution of a cyanovinyl compound to be adsorbed thereon, and then dispersed in a solvent solution of a binder resin. ■After dispersing the hole-transporting charge-generating pigment in a binder resin solvent solution and coating it to form a film,
The coating is treated and impregnated with a solution of a cyanovinyl compound.

Furthermore, during this dispersion, the charge generating pigment particles have an average particle size of 3.
It is effective to make the particle size less than μm, preferably less than 0.5 m.

In addition, the solvents used for dispersion include methanol,
Ethanol, n-propertool, n-butanol, pencil alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone,
Common organic solvents such as methyl acetate, dioxane, tetrahydrofuran, methylene chloride, and chloroform can be used alone or in combination of two or more.

As the coating method used when providing the charge generation layer, a conventional method such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method may be used. I can do it.

The thickness of the charge generation layer is generally set in the range of 0.05 to 5JIM1, preferably 0.1 to 2.0μs.

The charge transport layer in the electrophotographic photoreceptor of the present invention is formed by containing a charge transport material in a suitable binder resin. As charge transport materials, oxadiazole derivatives such as 2.5-bis(p-diethylaminophenyl)-1,3,,4-oxadiazole, 1.3.5-triphenyl-pyrazoline, 1-[pyridyl -(2)] Pyrazoline derivatives such as -3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, aromatic tertiary amine compounds such as triphenylamine and dibenzylaniline, N, N' -bis-(3-methylphenyl)-[
Aromatic tertiary diamino compounds such as 1,1'-biphenyl]-4,4'-diamine, 3-(4'-dimethylaminophenyl)-5,6-di(4'-methoxyphenyl)-1, 1,2,4-triazine derivatives such as 2,4-triazine, 4-diethylaminobenzaldehyde-1,
Hydrazone derivatives such as 1'-diphenylhydrazone, 2
-quinazoline derivatives such as phenyl-4-styrylquinazoline, benzofuran derivatives such as 6-hydroxy-2,3-di(p-methoxyphenyl)benzofuran, p-(2
, 2-diphenylvinyl)-N,N-diphenylaniline and other α-stilbene derivatives, “Journal of Imaging Science J
Imaging 5science) 29 Near ~ 10
(1985), carbazole derivatives such as N-ethylcarbazole, poly-N-
Vinyl carbazole and its derivatives, poly γ-carbazolylethyl glutamate and its derivatives, and also pyrene,
Known charge transport materials such as polyvinylpyrene, polygonylanthracene, polygonylacridine, poly-9-biphenylanthracene, pyrene-formaldehyde resin, and ethylcarbazole-formaldehyde resin can be used, but are not limited to these. isn't it. Further, these charge transport materials can be used alone or in combination of two or more kinds.

Further, as the binder resin, polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, vinyl chloride resin, vinylidene chloride resin, polystyrene resin, polyvinyl acetal resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, etc. Polymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene alkyd resin, poly-N
- Known resins such as vinyl carbazole can be used, but are not limited thereto. Further, these binder resins can be used alone or in combination of two or more types.

The blending ratio of the charge transport material and the binder resin is 10:1 to 1.
:5 (jutan ratio) is preferable. The thickness of the charge transport layer used in the present invention is generally 5 to 50 mm, preferably 10 to 3 mm.
It is set in the immediate range of 0.

As a coating method for forming the charge transport layer, conventional methods such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, and a curtain coating method can be used.

Furthermore, the solvents used when providing the charge transport box include aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene, ketones such as acetone and 2-butanone, and methylene chloride, chloroform, and ethylene chloride. Common organic solvents such as halogenated aliphatic hydrocarbons, cyclic or linear ethers such as tetrahydrofuran and ethyl ether can be used alone or in combination of two or more.

In the electrophotographic photoreceptor of the present invention, a protective layer may be provided on the charge transport layer, if necessary. This protective layer is used to prevent chemical deterioration of the charge transport layer when the photosensitive layer having a laminated structure is charged, and to improve the mechanical strength of the photosensitive layer.

This protective layer is formed by containing a conductive material in a suitable binder resin. N as a conductive material.

Metallocene compounds such as N'-dimethylferrocene, N,
Aromatic amino compounds such as N'-diphenyl-N, N'-bis(3-methylphenyl)-[1,1'-phenyl]-4°4'-diamine, antimony oxide, tin oxide,
Materials such as metal oxides such as titanium oxide, indium oxide, and tin oxide-antimony oxide can be used. In addition, as binding resins used for this protective layer, polyamide resins,
Known resins such as poly, urethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, and polyacrylamide resin can be used.

The thickness of the protective layer is 0.5-20uIr11, preferably 1-20uIr11
The range is set to 10 μm.

The electrophotographic photoreceptor of the present invention can be used in known electrophotographic image forming methods. In other words, it can be used in an image forming method that includes the steps of uniformly negatively charging the surface of a photoreceptor, performing imagewise exposure to form an electrostatic latent image, and developing it with charged toner particles. A copy image with image density can be obtained.

However, the electrophotographic photoreceptor of the present invention is particularly suitable for use in the following image forming method of forming an image by a so-called reversal development method.

That is, after the surface of the electrophotographic photoreceptor is uniformly negatively charged, an electrostatic latent image is formed by imagewise exposure, and the low potential area (exposed area) of the electrostatic latent image is negatively charged. A toner image is formed by attaching toner, a transfer material is placed on an electrophotographic photoreceptor that holds the formed toner image, and a positive charge is applied from the back side of the transfer material to transfer the toner image onto the transfer material. It is particularly suitable for an image forming method comprising:

To explain the image forming method to which the electrophotographic photoreceptor of the present invention is applied, means for uniformly charging the surface of the photoreceptor include a corona discharger such as a corotron, a scorotron, a dicorotron, a pin corotron, and a charging roller. etc. can be used. The initial charging potential is preferably set in the range of -700 to -200V.

Image exposure means include an illumination optical system consisting of an illumination lamp and an imaging optical system, a laser exposure optical system consisting of a laser beam generation source and a laser beam deflector, an LED array, a liquid crystal light valve, a vacuum fluorescent tube array, and an optical fiber array. , a leading wave tube array, or the like can be used, but it is preferable to use a light source that emits light with a wavelength in the spectral sensitivity region of the photoreceptor.

The electrostatic latent image formed by imagewise exposure is developed using a developer to form a toner image. As the developer, a two-component developer consisting of carrier and toner or a one-component developer consisting only of toner can be used. The toner particles may be magnetic toner containing magnetic powder inside, or non-magnetic toner. During development, a developing machine having a developer carrier carrying the developer is used to bring the toner particles close to or in contact with the electrostatic latent image.
Toner particles are selectively deposited depending on the potential of the electrostatic latent image.

In this case, depending on the charging polarity of the toner, the toner either adheres to the low potential area (exposed area) of the electrostatic latent image on the photoconductor (reversal development) or to the high potential area (unexposed area) (positive development). transfer and development), but these can be carried out by selecting the charging polarity of the toner. Since the electrophotographic photoreceptor of the present invention is essentially negatively chargeable, in the case of reverse development, a toner with negative charge polarity is selected, and in the case of forward development, a toner with positive charge polarity is selected. toner is selected.

During development, a bias voltage can be applied between the support of the electrophotographic photoreceptor and the developer carrier. As the bias voltage, a DC voltage or an AC voltage superimposed on a DC voltage can be used. Particularly when performing reversal development, it is necessary to apply a bias voltage equal to or lower than the potential of the non-exposed area.

The toner image formed by development can be transferred to a transfer material by any method. As a transfer means,
In addition to the above-mentioned corona charger, a transfer roll to which a transfer voltage is applied, a pressure roll, etc. can be used, but electric field transfer, which uses a corona discharger to transfer by applying a charge from the back side of the transfer material, is particularly effective. be. For example, negatively charged toner particles formed by reverse development are suitably transferred onto the transfer material by applying positive corona discharge from the back side of the transfer material.

After the transfer is completed, if necessary, the photoreceptor is cleaned of residual toner images (toner images that have not been transferred), and then static electricity is removed using an optional optical static eliminator or corona static eliminator,
It is prepared for the next image forming process.

Further, the electrophotographic photoreceptor of the present invention can also be suitably used in a so-called one-pass multicolor image forming method.

For example, after the surface of an electrophotographic photoreceptor is uniformly negatively charged, a first image exposure is performed to form a first electrostatic latent image, and a low potential portion of the first electrostatic latent image is formed. A first toner image is formed by depositing negatively charged toner on the surface of the toner, a second imagewise exposure is performed to form a second electrostatic latent image, and the height of the second electrostatic latent image is increased. A second toner image is formed by depositing positively charged second toner on the potential portion, and then, after aligning the polarities of the first and second toner images to one polarity, the first and second toner images are Transfer material is superimposed on the electrophotographic photoreceptor that holds the image,
Suitable for use in an image forming method comprising applying charges of polarity opposite to the polarities of the first and second toner images from the back side of the transfer material and transferring the first and second toner images onto the transfer material. I can do it.

In the one-pass multicolor image forming method described above, the same means as described above can be used as the means for uniformly negatively charging the photoreceptor, the image exposure means, the developing means, and the transfer means.

First, the surface of the photoreceptor is uniformly negatively charged, and then a first image exposure is performed. The first image exposure employs image area exposure in which a portion corresponding to the image area is exposed. The formed first electrostatic latent image is developed using a first developer to form a first toner image, but in this case, a bias voltage lower in potential than the initial charging potential is applied. Using a developer carrier, negatively charged first toner is attached to a low potential area (exposed area) of the first electrostatic latent image to form a first toner image.

Next, a second image exposure is performed, and in the second image exposure, a background portion exposure is employed in which a portion corresponding to a non-image portion is exposed. Moreover, the light source used for the second image exposure is
The light intensity is made weaker than that used for the first image exposure, and the exposure is performed so that the potential of the photoreceptor reaching the background area is reduced to approximately half of the initial charging potential. It is preferable to do so.

Next, the parts that were not exposed in the second image exposure (the second
A positively charged second toner is applied to the image area (in the image exposure). In this case, it is preferable to perform development by carrying the second toner on a developer carrying member to which a bias voltage higher than the potential of the photoreceptor corresponding to the background portion is applied.

In addition, since the second development is carried out on the photoreceptor on which the first toner is already supported, so-called overlapping development, there may be image disturbance of the first toner image or damage caused by the second developing machine carrying the first toner. In order to prevent the toner from being mixed into the toner, it is preferable to use a two-component developer consisting of toner and a negatively chargeable low-density carrier in the second development. Also, the carrier density is a, OQ/cy
It is preferable that it is less than or equal to t.

After forming the first and second toner images on the photoreceptor, these toner images are transferred onto a transfer material.

In this case, since these toners are charged with opposite polarities, it is necessary to align them to one of the polarities. In order to align the polarity, corona discharge using a transfer in charger can be used. The electrophotographic photoreceptor of the present invention includes:
Since the toner is negatively charged, it is preferable that the toner has a positive polarity. For pre-transfer charging, it is preferable to use an alternating current voltage on which a positive direct current voltage is superimposed.

Next, a transfer material is superimposed on the toner image on the photoreceptor, and the polarity opposite to that of the toner image is applied from the back side of the transfer material. A potential is applied to transfer the toner image onto the transfer material. In this case, it is preferable to use a negative DC voltage as the transfer potential.

Image formation is performed as described above, and the first toner and second toner can be selected from appropriate colors. For example, if the electrophotographic photoreceptor is drum-shaped, the drum A two-color image can be obtained during one rotation.

EXAMPLES Hereinafter, the electrophotographic photoreceptor of the present invention and an image forming method using the same will be explained with reference to examples.

Example 1 The surface of a mirror-cut aluminum pipe with an outer diameter of 40 mm and a diameter of 319 ax (7) was treated by puff polishing so that the surface roughness was Ra = 0.17. Then,
In order to form the undercoat layer, a mixed solution having the following composition was prepared.

Polyamide resin (Laccamite 5003 manufactured by Dainippon Ink Chemical v/J) 1 part by weight methanol
5 parts by weight n-butanol 3
Heavy” product description 1
Parts by weight The above mixture was applied by dip coating to give 11 parts by weight.
It was dried at 0°C for 10 minutes to form a subbing layer with a thickness of 11IIri.

A mixture of the following components was then prepared.

X-type metal-free phthalocyanine 1 part by weight cyanovinyl compound
) 0.3 equivalent polyvinyl butyral resin (trade name: S-LEC 881, manufactured by Sekisui Chemical ■) A mixture of 60 parts by weight of 1-layer cyclohexanone was dispersed for 10 hours using a sand mill using 1-diameter glass beads as a dispersion medium. A dispersion liquid having a pigment average particle size of about 0.05 μm was prepared. The resulting dispersion was applied onto the undercoat layer by dip coating, and heated and smoked at 120°C for 10 minutes to obtain a film thickness of 0.
A charge generation layer of 251Im was formed.

Furthermore, a mixture of the following components was prepared.

N,N'-diphenyl-N,N'-bis(3-methylphenyl)-N,1'-biphenyl)-4,4-diamine 2 parts by weight Polycarbonate resin (bisphenol type) 3 parts by weight Monochlorobenzene 20 parts by weight This mixture was coated on the charge generating layer by dip coating method and coated at 60°C at IIO'C.
It was dried for a minute to form a charge transport layer with a thickness of 20#I.

The electrophotographic photoreceptor thus prepared was negatively charged using a scorotron (grid applied voltage: -300V), and then exposed to light with a semiconductor laser (780 nm oscillation) to attenuate the light. Place the surface electrometer probe at the position after .3 seconds (corresponding to the position 0.6 seconds after charging), and compare the potential during non-exposure (VH) and the potential during exposure (V L : 30er(]/cn). exposure) was measured.

Further, a corotron (wire applied voltage: +5.0 KV) was placed after this probe to positively charge it, and then the charge was removed using a tungsten lamp. In this system, one cycle consisted of negative charging-exposure, positive charging, and removal-exposure, and changes in VH and VL were measured up to 200 cycles. This measurement was performed at 32°C, 85% RH: 20°C, 55%
R11; and under each environment of 10° C. and 15% RH.

The results are shown in Table 1.

In addition, the above electrophotographic photoreceptor was installed in a laser printer (product name: XP-11, manufactured by Fuji Xerox U), and an A4
After printing 500 sheets continuously on A4 size paper, print only on B4 size paper, and check the density difference between the area where A4 size paper passed and the other areas, and the background fog in each area. About, 32℃, 85%R
Evaluation was made under H environment. The results are shown in Table 2 below.

Note that this laser printer uses negative polarity magnetic component toner as the developer, and has a DC+4.8
The toner image attached to the exposed area was transferred by a KV transfer corotron.

Examples 2 to 7 The amount of the cyanovinyl compound (Exemplary Compound 14) was adjusted to 0.005 equivalent m (Example 2>
, 0.01 equivffl (J used IM3), 0.1 equiv m ('ltMglJ4), i, o equivalent (Example 5
), 2.0 equivalents (Example 6) or 4.0 equivalents (Example 7), electrophotographic photoreceptors were prepared in exactly the same manner as in Example 1, and evaluated in the same manner. The results are shown in Tables 1 and 2.

Comparative Example 1 Example 1 except that no cyanovinyl compound was added.
An electrophotographic photoreceptor was prepared in exactly the same manner as above, and evaluated in the same manner. The results are shown in Tables 1 and 2.

Examples 8 to 14 Electrophotographic photoreceptors were prepared in exactly the same manner as in Example 1, except that the cyanovinyl compound was changed to the compound shown in Table 1, and evaluation was performed in the same manner. The results are shown in Tables 1 and 2.
Shown in the table.

Examples 15-21 Except that the X-type metal-free phthalocyanine and cyanovinyl compound in Example 1 were changed to the compounds shown in Table 3,
An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1, and evaluated in the same manner. The results are shown in Tables 3 and 4.

Comparative Examples 2-8 Example 1 except that no cyanovinyl compound was added
An electrophotographic photoreceptor was prepared in exactly the same manner as above, and evaluated in the same manner. The results are shown in Tables 3 and 4.

Examples 22 to 29 A mirror-cut aluminum pipe with an outer diameter of 84 #φ and a length of 310 M was used as the substrate, perylene content (exemplified compound v-1) was used as the charge-generating pigment, and No. 5 was used as the cyanovinyl compound. An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1, except that the compounds shown in the table were used.

The electrophotographic photoreceptor thus prepared was negatively charged using a scorotron (grid applied voltage: -300V), and then a halogen lamp (550n
The light is attenuated by exposure using an interference filter with a central wavelength of m, and the position after 0.3 seconds (after charging,
Place the surface electrometer probe at the position corresponding to the position after 0.6 seconds, and compare the potential during non-exposure (VH>) and the potential during exposure (VL:
30erg/rn exposure). Furthermore, after this probe, a corotron (wire applied voltage: +5.0
KV) was placed and positively charged, and then static electricity was removed using a tungsten lamp. In this system, negatively charged −
One cycle consisted of exposure, positive charging, and removal, and changes in VH and VL were measured up to 200 cycles. This measurement is
32°C, 85% RH: 20°C, 55% R11: and 1
The test was carried out under each environment of 0'0115% RH. The results are shown in Table 5.

Comparative Example 9 An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 22, except that the cyanovinyl compound was not added, and evaluation was performed in the same manner. The results are shown in Table 5.

Comparative Examples 10 and 11 In Example 22, perylene pigment (exemplified compound v-1
Electrophotographic photoreceptors were prepared in exactly the same manner except that dibromoanthanthrone or a bisazo pigment represented by the following structural formula was used in place of ), and evaluations were conducted in the same manner. The results are shown in Table 5.

Comparative Examples 12 and 13 Electrophotographic photoreceptors were prepared in exactly the same manner as in Examples 10 and 11, except that no cyanovinyl compound was added, and evaluated in the same manner. The results are shown in Table 5.

Example 30 and Comparative Example 14 Using the electrophotographic photoreceptors prepared in Example 1 and Comparative Example 1, a scorotron (grid applied voltage: -30
0V), and then imagewise exposed to a semiconductor laser (780 nm oscillation) to attenuate the light.
A surface electrometer probe was placed at a position 0.3 seconds after exposure (corresponding to a position 0.6 seconds after charging), and the potential during non-exposure (Vll>) and the potential during exposure (VL: 20erg
/cm exposure) was measured. Furthermore, after this probe,
A corotron (wire applied voltage: 5.0 KV) was placed to negatively charge the sample, and then the charge was removed using a tungsten lamp. In this system, negative charge-exposure-negative charge-removal exposure is considered as one cycle, and Vl up to 200 cycles.
and the change in V[ was measured. This measurement was carried out at 32°C and 85°C.
%Rtl: 20°C155%R11; and 10'C
The test was carried out under each environment of 115% R1-1. The results are shown in Table 6.

Table 6 Example 31 and Comparative Example 15 The base body had an outer diameter of 84 #φ and a length of 310 mm. The surface of the mirror-cut aluminum pipe is polished with a whetstone.
The treatment was performed so that the surface roughness was Ra=0.1511Ir1. Next, an electrophotographic photoreceptor was produced in the same manner as in Example 1 or Comparative Example 1.

The electrophotographic photoreceptor created in this way is transferred to a copying machine (
FX2700, manufactured by Fuji Xerox ■) modified two-color laser printer (electronic electricity - Next laser exposure - Negatively charging red toner development on exposed areas - Secondary laser exposure - Positively charging black toner development on unexposed areas) - AC with positive DC superimposed
Pre-transfer charging - Transfer by applying negative DC corotron - Cleaning - Repeated static elimination), and repeat a red and black mixed pattern 50 times on B4 size paper.
0 sheets were printed and changes in print density in red and black areas were observed.

In the electrophotographic photoreceptor of Example 31, clear printing with no fog in the background area was achieved in both red and black areas, but in the electrophotographic photoreceptor of Comparative Example 15, red toner was printed in the background area as well as in the number of continuous sheets. Fog started to increase, the red print started to get thicker, and the black print became thinner.

Effects of the Invention The electrophotographic photoreceptor of the present invention has a charge generating layer containing a hole transporting charge generating pigment in a binder resin and a cyanovinyl compound represented by the above general formula (1), as described above. Compared to the case where no cyanovinyl compound is added, the sensitivity is improved, the charging property is good, the photosensitivity and charging potential are stable against environmental changes, and the exposed and non-exposed areas are It has an excellent effect that the potential is stable without decreasing even when a large number of copies are made.

The electrophotographic photoreceptor of the present invention is particularly applicable to an electrophotographic image forming method that repeats the following operations: negative charge, image exposure, reversal development, positive charge transfer, and charge removal, for example, in a laser printer, etc. It is suitable for use in cases where the surface potential of the photoreceptor used for image exposure is constant, from the initial image forming operation to after repeated image forming operations many times. There is no potential drop associated with this, and a stable surface potential is always maintained. Therefore, images with stable image density can be obtained.
Furthermore, the occurrence of fog can be suppressed.

In addition, even if the transfer paper is changed to a wider size one after repeating the image forming operation many times, the transfer density will not increase in the area corresponding to the width difference of the transfer paper, and therefore the background It is possible to obtain images with uniform density without fogging.

Note that when the charge generation layer does not contain the cyanovinyl compound, the potential of the exposed and non-exposed areas gradually decreases with repeated image forming operations, the image density gradually increases, and the background area becomes foggy. occurs. Also, if you change the transfer paper to a wider size after repeating the image forming operation many times, you may notice an increase in image density and fog in the background area of the transfer paper in the area corresponding to the width difference. It will be done.

Furthermore, the electrophotographic photoreceptor of the present invention can also be applied to a so-called one-pass multicolor image forming method.

[Brief explanation of the drawing]

1 to 4 are schematic cross-sectional views for explaining the structure of the electrophotographic photoreceptor of the present invention, respectively. DESCRIPTION OF SYMBOLS 1... Charge generation layer, 2... Charge transport layer, 3... Conductive support, 4... Subbing layer, 5... Protective layer. Patent applicant Fuji Pilots Co., Ltd. Agent
Patent attorney Tsuyoshi Seibu Figure 1 Figure 3 Figure 4 Procedural amendment (voluntary) July 19, 1999 Director General of the Patent Office Yoshi 1) Takeshi Moon 1, Indication of the case 1988 Patent Application No. 116856 2 , Title of the invention Electrophotographic photoreceptor and image forming method 3, Relationship to the case of the person making the amendment Patent applicant address 3-3-5 Akasaka, Minato-ku, Tokyo Name (
549) Fuji Xerox Co., Ltd., Representative: Yotabe Kobayashi 4, Agent address: 1-8-5-6 Kanda Nishiki-cho, Chiyoda-ku, Tokyo 101 Contents of amendment (l) Amend the "Scope of Claims" as shown in the attached sheet do. ■ Correct "ni." in the fourth line of page 5 of the specification to "ni,". (2) Correct "charge transport layer 2" in line 7 of page 10 to "charge transport layer 3" 4) Correct "magnet" in line 13 of page 11 to "grindstone". ■ Correct "indicate]" on page 15, line 17 of the same page to "indicate)". (Correct rAJ on the 4th line of page 25 of 61 to rDJ. ■ “A and B” on the 6th line of page 25 of the same year are changed to “D and E”.
Correct to. ■ "Consideration" in lines 19-20 of page 53 is "considerable"
Correct to. ■ Correct the "content" in the 4th line of page 66 to "pigment". Above [Attachment] 2. Claims (1) An electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer sequentially laminated on a support, wherein the charge generation layer has a hole transport property in a binder resin. charge-generating pigment and the following general formula (1)
An electrophotographic photoreceptor comprising a cyanovinyl compound represented by: (In the formula, A represents an optionally substituted aromatic group or an optionally substituted heterocyclic group, X represents a hydrogen atom or a halogen atom, and R1 represents a cyano group (however, when n-1 may be an aryl group), an alkoxycarbonyl group, an aryloxycarbonyl group, an aminocarbonyl group, an acyl group, an optionally substituted benzoyl group, or an optionally substituted phenyl group, and R2 is a hydrogen atom or an alkyl group. or represents a cyano group, n represents 0 or 1, and m represents 1
or 2) (2) The electrophotographic photoreceptor according to claim 1, wherein the cyanovinyl compound is contained in an amount of 0.01 to 2 equivalents based on the hole-transporting charge-generating pigment. (2) The electrophotographic photoreceptor according to claim 1, wherein the hole-transporting charge-generating pigment is a phthalocyanine pigment, a square aryllium pigment, or a perylene pigment. (4) The cyanovinyl compound has the following general formula (II)
An electrophotographic compound according to claim 1, which is a compound represented by (wherein R2 represents a hydrogen atom, an alkyl group or a cyano group,
R to R7 are each a hydrogen atom, an alkyl group, an alkoxy group, an aryloxy group, an aryl group, an alkenyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group, a halogen atom, a cyano group, or Indicates a nitro group, or an atomic group necessary for two adjacent groups to bond to form an aromatic ring or a heterocycle. ) ■ After the surface of the electrophotographic photoreceptor according to claim 1 is uniformly negatively charged, imagewise exposure is performed to form an electrostatic latent image, and the low potential portions of the electrostatic latent image are negatively charged. A toner image is formed by adhering toner, a transfer material is superimposed on an electrophotographic photoreceptor that holds the toner image, and a positive charge is applied from the back side of the transfer material,
An image forming method characterized by transferring a toner image onto a transfer material. (e) After the surface of the electrophotographic photoreceptor according to claim 1 is uniformly negatively charged, a first image exposure is performed to form a first electrostatic latent image, and the first electrostatic latent image is A first toner image is formed by depositing negatively charged toner on the low potential portion of the toner, and then
A second image exposure is performed to form a second electrostatic latent image, and a positively charged second toner is attached to a high potential portion of the second electrostatic latent image to form a second toner image. After forming and aligning the polarities of the first and second toner images to one polarity, a transfer material is superimposed on the electrophotographic photoreceptor holding the first and second toner images, and the back side of the transfer material is An image forming method characterized in that the first and second toner images are transferred onto a transfer material by applying charges having polarities opposite to those of the first and second toner images.

Claims (1)

[Scope of Claims] (1) In an electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer sequentially laminated on a support, the charge generation layer contains a hole transporting charge generation pigment in a binder resin. and the following general formula ( I
) An electrophotographic photoreceptor comprising a cyanovinyl compound represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, A represents an optionally substituted aromatic group or an optionally substituted heterocyclic group, and X represents a hydrogen atom or a halogen atom. , R_1 is a cyano group (however, when n=1, it may be an aryl group), an alkoxycarbonyl group, an aryloxycarbonyl group, an aminocarbonyl group, an acyl group, an optionally substituted benzoyl group, or an optionally substituted benzoyl group. represents a good phenyl group, R_2 represents a hydrogen atom, an alkyl group or a cyano group, n represents 0 or 1, m
1 or 2) (2) The electrophotographic photoreceptor according to claim 1, wherein the cyanovinyl compound is contained in an amount of 0.01 to 2 equivalents based on the hole-transporting charge-generating pigment. (3) The electrophotographic photoreceptor according to claim 1, wherein the hole-transporting charge-generating pigment is a phthalocyanine pigment, a squareryllium pigment, or a perylene pigment. (4) The electrophotographic photoreceptor according to claim 1, wherein the cyanovinyl compound is a compound represented by the following general formula (II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R_2 represents a hydrogen atom, an alkyl group, or a cyano group, and R_3 to R_7 each represent a hydrogen atom, an alkyl group, an alkoxy group, an aryloxy group, or an aryl group. group, alkenyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylcarbonyloxy group, arylcarbonyloxy group, halogen atom, cyano group or nitro group, or two adjacent groups are bonded to form an aromatic ring or (5) After uniformly negatively charging the surface of the electrophotographic photoreceptor according to claim 1, imagewise exposure is performed to form an electrostatic latent image. Then, a negatively charged toner is attached to the low potential portion of the electrostatic latent image to form a toner image, a transfer material is superimposed on the electrophotographic photoreceptor that holds the toner image, and a transfer material is applied from the back side of the transfer material. An image forming method characterized by applying a positive charge and transferring a toner image onto a transfer material. (6) After the surface of the electrophotographic photoreceptor according to claim 1 is uniformly negatively charged, a first image exposure is performed to form a first electrostatic latent image, and the first electrostatic latent image is formed. A first toner image is formed by depositing negatively charged toner on the low potential portions of the image;
A second image exposure is performed to form a second electrostatic latent image, and a positively charged second toner is attached to a high potential portion of the second electrostatic latent image to form a second toner image. After forming and aligning the polarities of the first and second toner images to one polarity, a transfer material is superimposed on the electrophotographic photoreceptor holding the first and second toner images, and the back side of the transfer material is An image forming method characterized in that the first and second toner images are transferred onto a transfer material by applying charges having polarities opposite to those of the first and second toner images.