JPH0297959A - Electrophotographic sensitive body and image forming method - Google Patents

Abstract

PURPOSE:To improve the sensitivity and the electrifiability of the subject body, an to suppress the reduction of the potential in the exposed and the nonexposed parts of the sensitive body even at the time of copying the large volumes of sheets by incorporating a specified dicyanovinyl compd. in the photosensitive body. CONSTITUTION:In the photosensitive body obtd. by laminating the charge generating layer 1 and a charge transfer layer 2 in this order on a substrate body 3, the layer 1 is formed by applying a dispersion dispersed a charge generating pigment having positive hole transferring property and the compd. shown by formula I in a binding resin solution, on the substrate 3. In the formula, A is a prescribed group. The compd. shown by the formula is composed of a compd. shown by formula II, etc. A 1st toner image is formed by being subjected the photosensitive body to negative electrification to perform a first image exposure, and to form its latent image and then being stuck a negative charged toner to the low potential part of the obtd. electrostatic latent image. Next, a 2nd toner image is formed by exposing the 2nd image to form its latent image, and being stuck a positive charged toner to the high potential part of the obtd. latent image. A two colored picture is formed by arranging the polarities of the both toner images to one polarity, and then transferring the toner image on the transferring material, followed by fixing the toner image on the material.

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
Problems were encountered in terms of flexibility, etc.

In recent years, in order to solve the drawbacks of inorganic photoconductive materials, research into electrophotographic photoreceptors using organic photoconductive materials has been actively progressed, and electrophotographic photoreceptors made of polyvinylcarbazole and 2,4,7-dolinitrofluorenone have been developed. Electrophotographic photoreceptors using charge transfer complexes, electrophotographic photoreceptors using eutectic complexes of pyrylium salt and alkylidene diarylene, and the like 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 cyanvinyl compound together with an electron donating charge transfer substance in the charge transport layer to prevent an increase in residual potential. There is.

(Japanese Unexamined Patent Publication No. 58-7643) 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 aims 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,
The 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 photoconductor negatively to form an electrostatic latent image, and then attach negatively charged toner to a low potential portion of the electrostatic latent image to form a toner image. An object of the present invention is to provide an electrophotographic photoreceptor suitable for use in an image forming method including a step of forming an image and 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 dicyanovinyl compound represented by the following general formula (I>).

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. Contains a pigment and a dicyanovinyl compound represented by the following general formula (I) [wherein, A represents a hydrogen atom or an alkyl group, and R3 represents a hydrogen atom, a nitro group, or an alkyl group] ), R
1 represents a hydrogen atom-nitro group, an alkyl group, an alkoxycarbonyl group, a halogen atom, an aryl group, an aryloxy group, or a cyano group. ] Hereinafter, the electrophotographic photoreceptor of the present invention will be explained.

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 retainer 8M5 is provided on the surface of the charge transport layer 3, and in FIG. A protective layer 5 is provided on the surface.

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, tin oxide-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 within a range that does not affect image quality. For example, a light absorption layer may be provided on the surface of the conductive support 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. , light scattering treatment may be performed. Light scattering treatment methods include sandblasting, liquid honing, magnetic polishing, puff polishing, belt sanding, brush polishing, steel wool, acid etching,
Alkaline 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 attached to the conductive support. In some cases, the conductive support acts as an adhesive layer to prevent the reflection of light from the conductive support.

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 gelatin can be used.

Further, the thickness of the subbing layer is 0.01 to 10, preferably 0.
．． 05-3p is suitable. Furthermore, the coating method used when providing the undercoat layer is 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, a curtain coating method, etc. be able to.

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

The charge-generating pigment used together with the dicyanovinyl compound must itself have hole-transporting properties. To determine whether a charge-generating pigment has hole-transporting properties,
The 1j constant method may be used, in which the pigment is vapor-deposited or dispersed in a resin at a high concentration and applied to the substrate to form a multilayer, which is positively or negatively charged and the optical attenuation is measured. 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.

Squareylium pigments are represented by the following general formula % formula % (wherein B and C are respectively in the following formula 1, R4 and R5 are a hydrogen atom, a hydroxyl group,
A fluorine atom, an alkyl group, N R12R13 (here, R12 and R13 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 R6 is , -NR14R15 (here, R14 and R15 each represent an alkyl group, an aryl group, or an aralkyl group), and R7 to R10 each represent a hydrogen atom, an alkyl group, an aryl group, or -CO
NHR16 (here, RlB represents an alkyl group, aryl group or aralkyl group), a halogen atom, an alkoxy group or an aryloxy group, R11 is an alkyl group,
Represents an aryl group or an aralkyl group, Z is 〉CR17R
18, -3--CR,7=CR18-(here, R1□
and R18 each represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group).Specifically, the following can be exemplified.

Examples of the phthalocyanine pigment include those represented by the following general formula (II).

(In the formula, R19 is a hydrogen atom, an alkyl group, an aryl group,
It represents an aralkyl group, a halogen atom, a cyano group, or a nitro group, and M is two hydrogen atoms, or Cu, N +
, Go, Fe, MnXQr, Ti, Ru, Pd, I
n, Sn, Sb, Zn, Mg, Ga, Ge, As, S
i, Hg, ++, vXu.

and Pd, D and E each represent a halogen atom or an oxygen atom, and X and y are
Each indicates O or 1. However, when M is a divalent metal atom, both X and y represent 0; when M is a trivalent metal atom, X represents 1, y represents O, and M is a tetravalent metal atom. In the case of atoms, X and y both represent 1, when M is V, D is an oxygen atom, X is 1, y represents O, and when M is ■, D and E are oxygen atoms. (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 phthalocyanine, tin. Examples include phthalocyanine, lead phthalocyanine, and halides of the above phthalocyanines.

Further, as perylene pigments, for example, the following general formula (I
V) (wherein R2
(0 represents an optionally substituted alkyl group, aryl group, or aralkyl group) Specifically, the following can be exemplified.

On the other hand, as specific examples of the dicyanovinyl compound represented by the above general formula (I>), the following can be exemplified.

Below margin N01 NO2 ■-4 ■-T Knee 8 l-9 ■-11 ■-12 Below margin ■-13 Knee 14 Knee 16 The dicyanovinyl compound represented by the above general formula (I) is
It can be synthesized according to the reaction formula below.

(In the formula, A and R1 each have the same meaning as above.) Examples thereof will be shown below.

Synthesis Example 25.0ch (135m mol) of p-nitrobenzoyl chloride was added to a 500m, Il three-bottle flask.
Aluminum chloride 20.0g (150m mol),
Add 200ml of methylene chloride, stir at -10'C under a nitrogen stream for 5 hours, then add 9.15ml of diphenylmethane.
A solution of methylene chloride (55 mmol) and methylene chloride (50 m fJ) was slowly added dropwise over about 40 minutes, and after the dropwise addition was completed, stirring was continued for 2 hours. After removing the cold bath and stirring at subtemperature for 15 hours, aluminum chloride 10. OQ (75mm
ol> was added and refluxed for 24 hours. After the reaction was completed, the mixture was cooled and poured into 300 Cl of ice, a 20% aqueous potassium hydroxide solution was added until the aluminum hydroxide was dissolved, the organic layer was separated, and the aqueous layer was further extracted with methylene chloride. After combining all the organic layers and distilling off the solvent under reduced pressure, 7% potassium hydroxide was added at 300 m J! was added and heated on a water bath at about γ0° C. for about 1 hour to decompose the acid chloride, and then the precipitate was filtered off and washed with ethyl acetate to obtain a pale yellow powder. This was further recrystallized from ethanol-methylene chloride to obtain 11.8 g (46.0%) of a compound having the following structural formula as a pale yellow powder. Melting point: 193-195°C.

500m, Il (7) 3 mouths”) -y';1
．． D D, 10.0 g (21.4 mmol) of the above compound
), malonitrile 5.7 g (85.8 mmol)
, 80 mβ of pyridine was added, and after 3 hours of centrifugation under a nitrogen stream, the lysine was distilled off under reduced pressure. The residue was dissolved in methylene chloride, washed with dilute hydrochloric acid and then water, dried over Na2SO4, purified on a short silica gel column (eluted with methylene chloride), and evaporated. The residue was recrystallized from ethyl acetate to give the above-mentioned exemplified compound (nee 2 > 5.3 t
j (44.1%) was obtained as pale pink needle-like crystals. Melting point 2
The infrared absorption spectrum at 26 to 228° C0 is shown in FIG.

Binding resins for the hole-transporting charge-generating pigment and the dicyanovinyl compound include polystyrene, silicone resin, polycarbonate resin, acrylic resin, methacrylic resin, polyester, vinyl resin, cellulose, and alkyd resin. If it is a conventionally known item, such as,
Any kind of material can be used.

In the charge generation layer of the present invention, the dicyanovinyl compound has o,
It is contained in the range of Oi to 2 equivalents, preferably O11 to 1 equivalent. If the amount of the dicyanovinyl compound is less than 0.01 equivalent, the effect on increasing photosensitivity and reducing environmental fluctuations and repetitive fluctuations in the potential of exposed/non-exposed areas will be reduced, and it will be less effective than 2 equivalents. The above range is preferable because if it is too high, the dark attenuation will greatly increase, the charging potential will decrease, and in an electrophotographic process in which toner is formed in non-exposed areas, the background area will be more likely to be fogged.

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 employed to incorporate the hole-transporting charge-generating pigment and the dicyanovinyl compound into the charge-generating layer. For example, it can be contained in the following manner. ■The hole-transporting charge-generating pigment and the dicyanovinyl compound are both added to the binder resin solvent solution and dispersed.The dispersion method is the ball mill dispersion method.
Commonly employed methods such as attritor dispersion, sand mill dispersion, and ultrasonic dispersion can be used. ■First, a hole-transporting charge-generating pigment is dispersed in a binder resin solvent solution.
A dicyanovinyl compound is added to the resulting dispersion.

(2) A hole-transporting charge-generating pigment is previously treated with a dicyanovinyl compound solution to be adsorbed thereon, and then dispersed in a binder resin solvent solution.

(2) A hole-transporting charge-generating pigment is dispersed in a solvent solution of a binder resin, and a film is formed by coating, and then the film is treated with a solution of a dicyanovinyl compound to impregnate it.

Furthermore, during this dispersion, the charge generating pigment particles have an average particle size of 3.
It is effective to use a particle size of #7 or less, preferably 0.5 particles or less.

In addition, the solvents used for dispersion include methanol,
Ethanol, n-propertool, n-butanol, benzyl 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. Can be done.

The thickness of the charge generation layer is generally set in the range of 0.505 to 50, preferably 0.1 to 2.0.

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(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'-bisulfur (3-methylphenyl) -[
Aromatic tertiary diamino compounds such as 1,1'-biphenyl]-4,4'-diamine, 3-(4'-dimethylaminophenyl)-5,6-di(4'-methoxyphenyl)
1,2,4-triazine derivatives such as -1,2,4-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 (Journal of
Imaging 5science) 29: 7-1
0 (1985), N-
Carbazole derivatives such as ethylcarbazole, poly-N
- Vinylcarbazole and its derivatives, poly γ-carbazolylethyl glutamate and its derivatives, as well as pyrene, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-biphenylanthracene, pyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin, etc. Any of the known charge transport materials can be used, but is not limited thereto. 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-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 (weight ratio) is preferable. The thickness of the charge transport layer used in the present invention is generally 5 to 50 μm, preferably 10 to 50 μm.
It is set in the range of 30/ffl.

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, examples of solvents used when forming the charge transport layer 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. Examples of conductive materials include metallocene compounds such as N,N'-dimethylferrocene, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,
Materials such as aromatic amine compounds such as [1'-phenyl]-4,4'-diamine, and metal oxides such as antimony oxide, tin oxide, titanium oxide, indium oxide, and tin oxide-antimony oxide can be used.

Further, as the binder resin used for this protective layer, known resins such as polyamide resin, polyurethane resin, polyester resin, Epoquin resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, etc. can be used. can.

The thickness of the protective layer is 0.5 to 20 #I, preferably 1 to 10
It is set in the μm range.

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, corona dischargers such as a corotron, scorotron, dicorotron, and pincorotron, charging rollers, etc. are used as means for uniformly charging the surface of the photoreceptor. 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, a toner with a negative charge polarity is selected in the case of reverse development, and a toner with a positive charge polarity is selected in the case of forward development. 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 were not transferred), and then static electricity is removed from the photoreceptor using an optional optical static eliminator or corona static eliminator, and the photoreceptor is cleaned for the next image forming process. will be prepared.

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 the low potential portion of the first electrostatic latent image is A negatively charged toner is deposited to form a first donor image, followed by a second imagewise exposure to form a second electrostatic latent image, and a high potential of the second electrostatic latent image is applied. A second toner image is formed by attaching a positively charged second toner to the area, and then, after aligning the polarities of the first and second toner images to one polarity, the first and second toner images are formed. The transfer material is superimposed on the electrophotographic photoreceptor that holds the
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. Can be done.

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 foreground 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 corresponding to the background part is reduced to approximately half of the initial charging potential. is preferred.

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.

Furthermore, since the second development is carried out on the photoreceptor on which the first toner has already been carried, 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 density of the carrier is 4.0g/Cr
Those below A are preferred.

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 can be performed using a pre-transfer charger. Since the electrophotographic photoreceptor of the present invention 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 revolution.

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 anφ and a length of 319 mm was treated by puff polishing so that the surface roughness was Ra=0.17. Next, in order to form an undercoat layer, a mixed solution having the following composition was prepared.

Polyamide resin (Laccamite 5003 manufactured by Dainippon Ink Chemical) 1 Manual laboratory methanol
5 parts by weight n-butanol 3 parts by weight water 1 Molding part The above mixture was applied by dip coating and heated at 110°C.
This was dried for 10 minutes to form a subbing layer with a thickness of 11M. A mixture of the following components was then prepared.

Type X metal-free phthalocyanine 1 part by weight dicyanovinyl compound based on pigment (Example Compound 2)
A mixture of O13 equivalent polyvinyl butyral resin (trade name: S-LEC 881, manufactured by Hosui Kagaku ■) 1 part by weight cyclohexanone 60 parts by weight was dispersed for 10 hours in a sand mill using 1rM 1φ glass beads as a dispersion medium, and the average particle size of the pigment was A 0.05 diameter dispersion was prepared. The resulting dispersion was applied onto the undercoat layer by dip coating, and dried by heating at 120°C for 10 minutes to obtain a film thickness of 0.
．． A charge generation layer of 25IIIft was formed.

Furthermore, a mixture of the following components was prepared.

N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-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 generation layer by dip coating and dried at 110° C. for 60 minutes to form a charge transport layer with a thickness of 20 mm.

The electrophotographic photoreceptor thus prepared was negatively charged using a scorotron (grid applied voltage: -300V), and then exposed to a semiconductor laser (780 nm emission) for light attenuation. After exposure, A surface electrometer probe was placed at the position after 0.3 seconds (corresponding to the position 0.6 seconds after charging), and the potential during non-exposure (VH) and the potential during exposure (V L : 30erg/ci exposure) ) was measured. Furthermore, 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 of negative charge-exposure, positive charge, and removal exposure was performed. year,
2 [) Changes in VH and V-S up to 0 cycles were measured.

This measurement was performed at 32°C and 85% l? tl; 20℃, 5
Testing was carried out under the following environments: 5% R11; and 10° C., 15% R1-1. 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 ■), and A4 size paper
After continuous printing, print only on B4 size paper, and check the density difference between the area where the A4 size paper passed and the other areas, and the background fog in each area at 32℃. Evaluation was performed under an environment of 85% RH. 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 using a V transfer corotron.

Examples 2 to 7 The amount of the dicyanovinyl compound (exemplary compound ①-2) was adjusted to 0.005 equivalents (Example 2>
, 0.01 equivalent (Example 3), 0.1 equivalent (Example 4)
), 1.0 equivalent (Example 5), 2.0 equivalent (Example 6), or 4.0 equivalent (Example 7). was created and evaluated in the same way. The results are shown in Tables 1 and 2.

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

Examples 8 to 11 Electrophotographic photoreceptors were prepared in exactly the same manner as in Example 1, except that the dicyanovinyl compound was changed to the compound shown in Table 1, and evaluated in the same manner. The results are shown in Tables 1 and 2.

An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1, except that the X-type metal-free phthalocyanine and dicyanovinyl compound shown in the following margin Examples 12 to 17 were changed to the compounds shown in Table 3. ,
Evaluation was conducted in the same manner. The results are shown in Tables 3 and 4.

Comparative Examples 2 to 7 Electrophotographic photoreceptors were prepared in exactly the same manner as Examples 12 to 17 except that no dicyanovinyl compound was added,
Evaluation was conducted in the same manner. The results are shown in Tables 3 and 4.

Examples 18 to 24 with blank spaces below A mirror-cut aluminum pipe with an outer diameter of 84#φ and a length of 310# was used as a substrate, perylene pigment (exemplified compound IV-1>) was used as a charge-generating pigment, and a dicyanovinyl compound was used as a charge-generating pigment. An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1, except that the compounds shown in Table 5 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 (Vll) and the potential during exposure (VL).
: 30erg/cffl exposure) was measured. Furthermore, after this probe, a corotron (wire applied voltage: +
5.0 KV) was placed to positively charge the battery, and then the static electricity was removed using a tungsten lamp. In this system, one cycle consists of negative charging-exposure, positive charging, and removal-exposure.
Changes in V) I and VL through the cycle were measured. This measurement was performed at 32°C, 85% RH; 20°C, 55% RH;
and 10° C. and 115% RH. The results are shown in Table 5.

Comparative Example 8 An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 18, except that the dicyanovinyl compound was not added, and evaluation was performed in the same manner. The results are shown in Table 5.

Comparative Examples 9 and 10 In Example 18, perylene pigment (exemplified compound IV-
An electrophotographic photoreceptor was prepared in exactly the same manner except that dibromoanthanthrone or the bisazo pigment represented by the following structural formula was not added in place of 1>, and evaluation was performed in the same manner. The results are shown in Table 5.

Electrophotographic photoreceptors were prepared in exactly the same manner except that blank spaces were used, and evaluations were conducted in the same manner. The results are shown in Table 5.

Comparative Examples 11 and 12 In Comparative Examples 9 and 10, dicyanovinyl compound Example 25 and Comparative Example 13 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 the position 0.6 seconds after charging), and the potential during non-exposure (VH) and the potential during exposure (V L : 20erg/
cm exposure) was measured. Furthermore, a corotron (wire applied voltage knee 5.0 KV) is placed after this probe,
It was negatively charged and then neutralized using a tungsten lamp. In this system, one cycle was negative charging-exposure, negative charging, and removal-exposure, and changes in VH and VL were measured up to 200 cycles. This measurement was carried out at 32°C and 85°C.
%R■; 20°C, 55%RH: and 10°C, 15%RH
It was conducted under each environment. The results are shown in Table 6.

Example 26 and Comparative Example 14 As a base, the surface of a mirror-cut aluminum pipe with an outer diameter of 84 mφ and a length of 310# was polished with a whetstone.
Surface roughness Ra=0.15#! It was processed so that

Next, an electrophotographic photoreceptor was produced in the same manner as in Example 1 or Comparative Example 1.

The electrophotographic photoreceptor produced in this way is transferred to a copying machine (
A two-color laser printer modified from FX2700 manufactured by Fuji Xerox ■ (Charging - Primary laser exposure - Negatively charging red toner development on exposed areas - Secondary laser exposure - Positively charging black toner development on unexposed areas - DC! (consisting of superimposed AC pre-transfer charging, transfer by applying a negative DC corotron, cleaning, and static elimination), and repeatedly printed a mixed pattern of red and black on 500 sheets of B4 size paper. Changes in print density in black areas were observed.

In the electrophotographic photoreceptor of Example 26, clear printing with no background fog was obtained in both the red and black areas, but in the electrophotographic photoreceptor of Comparative Example 14, red toner was applied to the background area as well as 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 dicyanovinyl compound represented by the general formula (I>) as described above. Compared to the case where no dicyanovinyl 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 This has an excellent effect in that the potential of the area remains stable without decreasing even when a large number of copies are made.

The electrophotographic photoreceptor of the present invention is particularly useful when applied to an electrophotographic image forming method that repeats the following operations: uniformly negatively charged, image exposure, reversal development, positively charged transfer, and static elimination, for example, when used in a laser printer, etc. In that case, the surface potential of the photoreceptor during image exposure will vary from the initial image forming operation to after a large number of image forming operations. A stable surface potential is maintained at all times without causing any problems, and therefore images with stable image density can be obtained and fogging 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.

In addition, when the above-mentioned dicyanovinyl compound is not included in the charge generation layer, 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 Fog 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-bath 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. FIG. 5 is an infrared absorption spectrum diagram of an example of a dicyanovinyl compound represented by the general formula (I>) used in the present invention. 1... Charge generation layer, 2... Charge transport layer, 3... ...Conductive support, 4. Undercoat layer, 5. Protective layer. Fig. 1 Fig. 2 Patent applicant: Agent for Fuji Xerox Co., Ltd.
Patent attorney Tsuyoshi Okibe Figure 3 Figure 4 Procedural amendment (spontaneous) July 19, 1999 Director General of the Patent Office Yoshi 1) Takeshi Moon 1, Indication of the case 1988 Patent Application No. 249741 2, Invention Name: Electrophotographic photoreceptor and image forming method 3; Relationship with the amended person case 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, Japan Contents of the amendment (1) "Electric charge" on page 9, line 10 of the specification The transport layer 3j is
charge transport layer 2". ■ Correct "magnet" in line 16 of page 10 to "grindstone". G) "Distribute," in the 13th line of page 32 is corrected to "disperse."that's all

Claims (5)

[Claims] (1) In an electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated on a support, the charge generation layer contains a hole transportable charge generation pigment in a binder resin and the following general formula ( I
) An electrophotographic photoreceptor comprising a dicyanovinyl compound represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) [In the formula, A is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, R_2 represents a hydrogen atom or an alkyl group, and R_
3 represents a hydrogen atom, a nitro group, or an alkyl group), and R_1 represents a hydrogen atom, a nitro group, an alkyl group, an alkoxycarbonyl group, a halogen atom, an aryl group, an aryloxy group, or a cyano group. ] (2) The electrophotographic photoreceptor according to claim 1, wherein the dicyanovinyl 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) 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 the 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 to transfer the toner image onto the transfer material. An image forming method characterized by: (5) 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.