JPH01158468A - Image forming method - Google Patents

Abstract

PURPOSE:To obtain a uniform image having a high image density and high quality by applying an electrostatic charge which is 400V-900V in the absolute value of an electrostatic charge potential to a specific photosensitive body, then forming an electrostatic latent image thereon by exposing, then by subjecting the image to a reversal development with the DC bias voltage having the absolute value lower than the absolute value of the electrostatic charge potential. CONSTITUTION:The photosensitive body having a carrier generating layer 6 in which a phthalocyanine compd. is incorporated as a carrier generating material and a charge blocking layer 7 in which polyvinyl butyral and/or polyvinyl formal is incorporated is used. After the electrostatic charge having 400V-900V absolute value of the electrostatic charge potential is applied to this photosensitive body, the electrostatic latent image is formed thereon by exposing and thereafter, the DC bias voltage having the absolute value lower by 0-200V than the absolute value of the charge potential is impressed thereto to execute the reversal development of the electrostatic latent image. The uniform image having the high image density and the high quantity is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an image forming method, and particularly to an electrophotographic copying method.

In the electrophotographic copying method of the prior art Carlson method, after the surface of a photoreceptor is charged, an electrostatic latent image is formed by exposure, and the electrostatic latent image is developed with toner. Transfer and fix onto paper, etc. At the same time, the photoreceptor is subjected to removal of adhered toner, neutralization of static electricity, and surface cleaning, and is used repeatedly over a long period of time.

Therefore, as an electrophotographic photoreceptor, it is important to not only have electrophotographic properties such as good charging characteristics, good sensitivity, and low dark decay, but also physical properties such as printing durability, abrasion resistance, and moisture resistance after repeated use. It is also required to have good physical properties and resistance to ozone generated during corona discharge, ultraviolet rays during exposure, etc. (environmental resistance).

Conventionally, as electrophotographic photoreceptors, inorganic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductive substance such as selenium, zinc oxide, or cadmium sulfide have been widely used.

On the other hand, the use of various organic photoconductive substances as materials for photosensitive layers of electrophotographic photoreceptors has been actively developed and researched in recent years.

For example, in Japanese Patent Publication No. 50-10496, Bo IJ
An organic photoreceptor having a photosensitive layer containing -N-vinylcarbazole and 2,4,7-dolinitro-9-fluorenone is described. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability.

In order to improve these drawbacks, attempts have been made to develop organic photoreceptors with high sensitivity and durability by assigning the carrier generation function and carrier transport function to different substances in the photosensitive layer. ing. In such so-called function-separated type electrophotographic photoreceptors, substances that exhibit each function can be selected from a wide range of materials, so it is relatively easy to produce electrophotographic photoreceptors with arbitrary characteristics. Is possible. Therefore, it is expected that organic photoreceptors with high sensitivity and durability can be obtained.

FIG. 8 shows a functionally separated electrophotographic photoreceptor using such an organic photoconductive substance.

This electrophotographic photoreceptor has a structure in which a carrier generation layer 6 and a carrier transport layer 4 are sequentially laminated on a conductive substrate 1, and is used for negative charging. That is, the photosensitive layer 8 is composed of the carrier generation layer 6 and the carrier transport layer 4.

In an electrophotographic photoreceptor having the above-mentioned layer structure, since the mobility of holes is higher than that of electrons when used with negative charging, it is possible to use photoconductive materials with hole transport properties that have good properties. This is advantageous in terms of sensitivity, etc.

In contrast, few electron-transporting materials have excellent properties or are carcinogenic, making them unsuitable for use. For this reason, the above-mentioned photoreceptor is used for negative charging. In this case, it is advantageous to use a material with a high hole transport ability in order to achieve high sensitivity.

However, in the above-described photoreceptor, carrier injection from the conductive substrate or lower layer side tends to occur when negatively charged as shown in FIG. 8, and as a result, the surface charge disappears microscopically, or It will decrease. The occurrence of such local carrier injection. .

The cause of this is not clear, but it is thought to be due to defects or non-uniformity on the surface of the conductive substrate or non-uniformity in the charge generation layer.

Such local carrier injection causes the following problems.

In other words, recently, reversal development has been widely adopted in printers that involve digital processing, but in the reversal development method, a toner image is formed in the exposed area (the area where the surface charge has disappeared, vL), and the toner image is formed in the unexposed area. No toner image is formed on (portion where surface charge is retained, vH).

However, in the reversal development method, if the surface charge microscopically disappears or decreases in the unexposed area due to carrier injection from the substrate or lower layer as described above, toner is developed in that area, and the so-called capri It becomes an image. This kind of capri is different from normal capri, and as mentioned above, it is a phenomenon that occurs when the surface charge on the photoreceptor disappears or decreases microscopically during reversal development, and is called "black spot". There is. These black spots are caused by toner locally adhering to the white background, so they are much more noticeable than when the black background is white, and they significantly reduce the quality of the image, and are inappropriate image defects. be.

As a way to solve these problems, the carrier transport layer 4
In this case, it is conceivable to reduce the content of carrier transport material (hereinafter sometimes referred to as CTM) or change the type of CTM or binder resin. All of these are intended to reduce the hole transport ability of the carrier transport layer 40 to suppress carrier injection into the photoreceptor surface, but in this photoreceptor, the photosensitivity decreases, the residual potential increases, the 1, which causes a decrease in 1vL1 stability during repeated use, and also causes a decrease in temperature characteristics, and at low temperatures, the photoreceptor characteristics are greatly deteriorated, such as an increase in +V and +.

There is also a method of reducing the content of the carrier-generating substance to the binder resin in the carrier-generating layer 6, but this results in a decrease in photosensitivity and an increase in 1V, resulting in insufficient image density.

Furthermore, it is conceivable to provide an undercoat layer between the conductive substrate 1 and the carrier generation layer 6, which has a function of shielding charge injection. Depending on the type of carrier-generating substance, the carrier-generating substance may aggregate, resulting in poor coating, resulting in an increase in black spots, a decrease in image density, and even image unevenness, resulting in significant inconvenience.

On the other hand, as a countermeasure from a process perspective, it is possible to increase the difference between the charging potential vH and the bias voltage vb0, but this does not mean that the potential v1 of the exposed area and the bias voltage vbc
Since the difference between the two images becomes smaller, the image density decreases.

As described above, there has been no known photoreceptor that eliminates image defects such as black spots and has good photoreceptor characteristics, and a technical solution to these mutually contradictory problems has been desired.

Furthermore, in recent years, semiconductor laser light sources have been used in electrophotographic copying methods, which are inexpensive, compact, and capable of direct modulation. Currently, gallium-aluminum-arsenic (Ga-A) is widely used in semiconductor lasers.
The lasing wavelength of the l-As)-based light emitting device is 750 nm.
It is more than a certain degree. Many studies have been made in the past in order to obtain electrophotographic photoreceptors that are highly sensitive to such long wavelength light. For example, it has been considered to add a sensitizer to photosensitive materials such as selenium and cadmium sulfide, which have high sensitivity in the visible light region, to extend the wavelength to a longer wavelength. Environmental resistance is not sufficient,
It is also toxic and has problems in practical application. Furthermore, the sensitivity of many known organic photoconductive materials is usually 700 nm.
Since there are few materials that are limited to the visible light region of m or less and have sufficient sensitivity to wavelengths longer than this, it has been difficult to use them in laser printers that use semiconductor laser light sources that are expected to be highly reliable.

Technological systems using such laser beams and the like are expected to be applied to printers, which is why the emergence of a useful image forming method using reversal development is desired.

C0 Purpose of the invention, 5
゜An object of the present invention is to provide an image forming method that can significantly reduce image defects such as black spots and obtain high-quality, uniform images with high image density in the reversal development method where black spots are likely to occur. It is in.

20 Structure of the invention and its effects The present invention provides an image forming method using a photoreceptor having a photosensitive layer provided with a carrier transport layer on a carrier generation layer, in which (a) a phthalocyanine compound is a carrier generation substance. ( b), the absolute value of the charged potential on this photoreceptor is 400V to 9
After applying a charge of 00V, an electrostatic latent image is formed by exposure, and then the absolute value of the charged potential is 0~200V.
The present invention relates to an image forming method characterized in that reverse development of the electrostatic latent image is performed by applying a DC bias voltage having a low absolute value.

However, the charging potential and the DC bias voltage have the same sign.

The present invention is characterized in that a phthalocyanine compound is contained in the carrier generation layer, and the material of the charge blocking layer provided between the carrier generation layer and the conductive substrate is specified.

That is, by providing a charge blocking layer between the conductive substrate and the carrier generation layer, it is possible to prevent the occurrence of black spots during reversal development. The reason for this is not clear, but -
He can be considered like a famous doctor.

That is, in the conventional photoreceptor as shown in FIG.
Carriers (holes) injected from the substrate 1 side easily pass through the carrier generation layer 6 and reach the surface of the photoreceptor via the carrier transport layer 4 having high hole transport properties. In other words, the carrier generation layer 6 cannot function as a barrier to local carrier injection.

In contrast, in the present invention, by providing a charge blocking layer between the substrate and the carrier generation layer, it is possible to provide a barrier against local carrier injection from the conductive substrate side. It is thought that this can prevent the loss and decrease of surface charge caused by Therefore, when reversal development is performed, no black spots are produced on the image, and a remarkable effect can be achieved in that a high-quality image without image defects can be obtained.

However, what is important here is the selection of the carrier generating substance and the material of the charge blocking layer, and the combination of the two.

That is, since the carrier generation layer is formed by coating directly on the charge blocking layer and is itself extremely thin, depending on the combination of the carrier generation substance and the material of the charge blocking layer, the carrier generation substance may aggregate or This is extremely inconvenient because coating defects occur, black spots increase significantly, photosensitivity decreases, and image unevenness occurs.

However, when it comes to selecting a suitable combination that will not cause coating defects from among the countless existing polymeric materials and numerous carrier-generating substances, there is no uniform selection method. The reality is that we have no choice but to determine a good combination through repeated experiments.

Here, as a result of various studies, the present inventor selected a combination of the above-described phthalocyanine compound and polyvinyl butyral and/or polyvinyl formal,
It has been found that very good results can be obtained.

That is, the above-mentioned phthalocyanine compound has excellent photosensitivity, and by using this compound as a carrier generating substance, the potential stability during repeated use of the photoreceptor is improved, there is less memory development, and there is less residual potential. and stable. Moreover, since this azo compound has high sensitivity in a long wavelength region, it is possible to provide a high-performance photoreceptor that is particularly suitable for image forming methods by reversal development using a semiconductor laser as a light source.

Furthermore, by containing polyvinyl butyral and/or polyvinyl formal in the charge blocking layer, the above phthalocyanine compound does not aggregate during coating formation of the carrier generation layer, and therefore black spots and image unevenness can be prevented during reversal development. At the same time, the phthalocyanine compound is uniformly dispersed in the carrier generation layer, and the inherent photosensitivity of the phthalocyanine compound can be exhibited without hindering it. Therefore, a high quality and uniform image can be provided, and the image density can also be increased.

Furthermore, what should be noted in the present invention is that since the present invention is limited to the above-mentioned range, if the defect as described above is set to 900V, the film thickness of the photosensitive layer becomes large, which reduces the sensitivity. Undesirable. In addition, in the present invention, lV
It is also important that lV, I-IVDal, which is the difference between , That is, IVHl-IV-0l<O
In the case of V, Capri occurs and Teshimai, Mata, 1vH
1-I VDOI > 200 VIF), carrier-attached N (in the case of a two-component developer) or adhesion of toner of opposite polarity (in the case of a bipolar-component developer) will occur.

According to the present invention, 1vH1=400 to 900
v (preferably 500-700V'), and 1VIIl-1vD, l = O ~ 200V <mt
Therefore, performing reversal development under these conditions is an essential condition to maintain high sensitivity and obtain good images with high image quality and no black spots. be.

Moreover, since it is based on the inversion method, especially when applied to a printer, the area of the character area (black background area) is smaller than the white background area (that is, the exposure surface area is smaller).
This method is advantageous in terms of preventing deterioration of the photoreceptor, etc., compared to the regular development method.

As described above, according to the present invention, by specifically selecting the type of carrier-generating substance and the material of the charge blocking layer, black spots, image unevenness, etc.
Carrier adhesion and fogging can be prevented, and high-quality images with uniform image density can be provided.

FIG. 1 illustrates a general configuration of a photoreceptor, such as an electrophotographic photoreceptor, used in the present invention.

In the photoreceptor shown in FIG. 1, a carrier generation layer 6 is provided on a conductive substrate 1 with a charge blocking layer 7 interposed therebetween.
A carrier transport layer 4 is provided on the carrier generation layer 6. 8 indicates a photosensitive layer.

In the photoreceptor shown in FIG. 1, an intermediate layer having a blocking function or the like may be provided between the carrier generation layer and the carrier transport layer. Further, a protective layer (protective film) may be formed on the surface of the photoreceptor in order to improve printing durability, for example, a synthetic resin film may be coated.

Generally, in the carrier generation layer, a particulate carrier generation substance and a carrier transport substance are bound together by a binder substance≦that is, they are dispersed in the layer in the form of a pigment.

Next, the phthalocyanine compound used as a carrier generating substance in the present invention will be described.

That is, it is known that phthalocyanine compounds, which are one type of organic photoconductive materials, have a photosensitive range expanded to a long wavelength range compared to other compounds. Various crystalline forms of phthalocyanine compounds have been discovered in the process of converting the α-7 thalocyanine compound into the stable crystalline β-type phthalocyanine compound. Examples of these phthalocyanine compounds exhibiting photoconductivity include those described in Japanese Patent Publication No. 49-4338.
X-type metal-free phthalocyanine compounds described in JP-A-58-182639 and JP-A-60-19151, τ, τ', η, η'-ya metal-free phthalocyanine compounds, patent applications In addition to the phthalocyanine compounds described in Sho 61-295784, various metal phthalocyanine compounds are exemplified.

For example, a patent application was filed in 1983 for titanyl phthalocyanine compounds.
There is one described in the specification of No. 2-241938.

In addition, *yyvt is exemplified as a phthalocyanine compound particularly suitable for semiconductor lasers.

(The following is a blank space, continued on the next page) The specific product names of the phthalocyanine exemplified compound polyvinyl butyral are Denka Butyral $4,000 and Denka Butyral $3,000.
(manufactured by Denki Kagaku Kogyo Co., Ltd.), XYHL (Union Carbide 1i), S-LEC BM-2, S-LEC BM
-8, S-LEC BM-1, S-LEC BL-1, S-LEC BL-3, S-LEC BL-8, S-LEC BL
-7, S-LEC BX-L, S-LEC BH-3 (manufactured by Block Chemical Industry Co., Ltd.), and the like.

Specific trade names of polyvinyl formal include the "Denka Formal" series (manufactured by Denki Kagaku Kogyo Co., Ltd.) such as "Denka Formal $20J".

In the carrier generation layer, the content ratio of the carrier generation substance to the binder substance is preferably 3/1 to 1/10, more preferably 3/1 to 1/3. When the content ratio of the carrier-generating substance is larger than the above range, black spots and the like appear significantly or tend to appear. However, if the proportion of the carrier-generating substance is too small, the photosensitivity, etc. will actually decrease.5゜The thickness of the carrier-generating layer is preferably 0.1 μm or more, and is within the range of 0.2 to 5 μm. It is more preferable.

The thickness of the carrier transport layer is preferably 10 μm or more.

The thickness of the entire photosensitive layer is preferably within the range of 10 to 40 μm, and more preferably within the range of 15 to 30 μm. If the film thickness is smaller than the above range, the charging potential will be low due to the thinness, and the printing durability will also tend to decrease. Furthermore, if the film thickness is larger than the above range, the residual potential will increase on the contrary, and the same phenomenon as described above will occur when the carrier generation layer is too thick, making it difficult to obtain sufficient transport performance. Therefore, the residual potential tends to increase during repeated use.

It is also possible to include a carrier transport substance in the carrier generation layer.

When a photosensitive layer is formed by dispersing a granular carrier-generating substance, the carrier-generating substance is in the form of powder with an average particle size of 2 μm or less, preferably 1 μm or less, and more preferably 0.5 μm or less. is preferred. Further, in the carrier transport layer, the carrier transport substance preferably has excellent compatibility with the binder substance.

Since K does not cause turbidity or opacity even if the amount of K is increased relative to the binder material, the mixing ratio with the binder material can be set at a very wide range. The generation layer is uniform and stable, resulting in better sensitivity and charging characteristics.
Further, a photoreceptor 5' capable of forming clear images with high sensitivity can be obtained.

Furthermore, especially when used in repeated transfer type electrophotography, it is possible to achieve the effect that fatigue deterioration is less likely to occur.

The thickness of the charge blocking layer is preferably within the range of 0.05 to 2 μm, more preferably 0.1 to 0.5 μm.

In the present invention, it is also possible to use one or more other carrier-generating substances together with the phthalocyanine compound. Carrier pigments that can be used together, cyanine dyes,
Examples include azulenium compounds.

The carrier transport substances used in the present invention include carbazole derivatives, oxazole derivatives, oxadiazole derivatives,
Thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidasilone derivatives,
imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives,
Oxacylone derivatives, benzothiazole derivatives, penzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, apolyridine derivatives, phenazine rust conductors, aminostilbene derivatives, triarylamine derivatives, phenylenediamine rust conductors, stilbene derivatives, poly-N-vinyl carbazole, Poly-1-vinylpyrene, poly-9
- One or two or more selected from vinylanthracene etc.
- It is described in the specification of No. 195881. The general formula is listed below.

The following general formula (1) or (II) as a carrier transport substance
) styryl compounds can be used.

- Formula [I]: (However, in this formula, R', R represents a substituted or unsubstituted alkyl group or aryl group, and substituents include an alkyl group, an alkoxy group, a substituted amine group, a hydroxyl group, a halogen group, etc.) Atom, aryl group is used.

Ar %Ar: represents a substituted or unsubstituted aryl group, and the substituent includes an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, and an aryl group.

R, R: Represents a substituted or unsubstituted oryl group or a hydrogen atom, and as a substituent, an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, or an oryl group is used. ) General formula [■]: (However, in this formula, R: substituted or unsubstituted aryl group, R: hydrogen atom,
Halogen atom, substituted or unsubstituted alkyl group, alkoxy group, amino group, substituted amino group, hydroxyl group, R7: represents substituted or unsubstituted aryl group, substituted or unsubstituted heterocyclic group. ) Also, as a carrier transport substance, the following general formula (1) (M)
, (P/a), (ml/b) or [v] hydrazone compounds can also be used.

General formula [■]: (However, in this formula, R8 and R9: each a hydrogen atom or) ・Rogen atom, (10 and R11: each a substituted or unsubstituted aryl group, Ar': a substituted or unsubstituted aryl group) represents an arylene group) General formula [■]: (However, in this formula, R: substituted or unsubstituted arylene group, substituted or unsubstituted carbazolyl group, or substituted or unsubstituted heterocyclic group) (R, R: hydrogen atom, alkyl group, substituted or RL< represents an unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.) General formula (Wa): (However, in this formula , R16: Methyl group, ethyl group, 2-hydroxyethyl group, or 2-chloroethyl group, R17: Methyl group, ethyl group, benzyl group, or phenyl group, R18: Methyl group, ethyl group, benzyl group, or phenyl group. .

General formula (IVb): (However, in this general formula, R1? is a substituted or unsubstituted naphthyl group; R20 is a substituted or unsubstituted alkyl group, aralkyl group, or aryol group; R21 is a hydrogen atom, an alkyl group group or alkoxy group; R22 and R25 are the same or different groups consisting of a substituted or unsubstituted alkyl group, aralkyl group, or aryl group.) General formula [V]: (However, in this general formula, R24: Substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group, R25: Hydrogen atom, substituted or unsubstituted alkyl group, or substituted or unsubstituted aryl group, Q: Hydrogen atom, halogen atom, alkyl group, substituted An amino group, an alkoxy group, or a cyano group, s represents an integer of 20 or 1.) A pyrazoline compound represented by the following general formula (M) can also be used as a carrier transport substance.

- Numerical formula [■]: (However, in this general formula, !: 0 or 1, R26 and R27: substituted or unsubstituted aryl group, R = substituent or unsubstituted aryl group or heterocyclic group , R2? and R: a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group or aralkyl group (however, both R29 and 130 are not hydrogen atoms, and the above l is When R29 is 0, R29 is not a hydrogen atom.) Furthermore, an amine derivative of the following general formula [■] can also be used as a carrier transport substance.

General formula [■]: (However, in this general formula, Ar', Ar5: represents a substituted or unsubstituted phenyl group, and a halogen atom, an alkyl group, a nitro group, or an alkoxy group is used as a substituent.

Ar, substituted or unsubstituted phenyl group, naphthyl group,
Represents an anthryl group, a fluorenyl group, and a heterocyclic group, and substituents include an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, an aryloxy group, an aryl group, an amino group, a nitro group, a piperidino group, a morpholino group, a naphthyl group, and anthryl. and substituted amino groups. However, an acyl group, alkyl group, aryl group, or aralkyl group is used as a substituent for the substituted amino group. ) Furthermore, a compound of the following general formula [■] can also be used as a carrier transport substance.

General formula [■]: R-N-Ar -N-Rs2 '34'! ! S RR (However, in this formula, Ar: represents a substituted or unsubstituted arylene group, R51, R52, R" and R": a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.) Furthermore, a compound of the following general formula (K) can also be used as a carrier transport substance.

General formula [■]: (However, CIF) - In the formula, Has, R5! , R'' and Rs8 are each a hydrogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, a benzyl group, or an aralkyl group, and R and R are each a hydrogen atom, a substituted or unsubstituted Number of carbon atoms: 1-4o
alkyl group, cycloalkyl group, alkenyl group, cycloalkenyl group, aryl group or aralkyl group (however, R
and R may jointly form a saturated or unsaturated hydrocarbon ring having 3 to 10 carbon atoms. ) R, R%R and R are each a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, an amino group, an alkyl group. It is an amino group or an arylamino group. ] An antioxidant can be contained in the carrier transport layer and the carrier generation layer. This can suppress the influence of ozone generated during discharge, and can prevent an increase in residual potential and a decrease in charged potential during repeated use.

Examples of the antioxidant include hindered phenol, hindered amine, paraphenylene diamine, aryl alkane, hydroquinone, spirochroman, spiroindanone and derivatives thereof, organic sulfur compounds, organic phosphorus compounds, and the like.

These specific compounds are disclosed in Japanese Patent Application No. 61-1628.
No. 66, No. 61-188975, No. 61-19587
No. 8, No. 61-157644, No. 61-195879
No. 61-162867, No. 61-204469, No. 61-217493, No. 61-217492, and No. 61-221541.

A polymeric organic semiconductor can also be included in the photosensitive layer.

Among these polymeric organic semiconductors, poly-N-vinylcarbazole or its derivatives are highly effective and are preferably used. Such poly-N-vinylcarbazole derivatives are those in which all or part of the carbazole ring in the repeating unit is substituted with various substituents, such as an alkyl group, a nitro group, an amino group, a hydroxy group, or a halogen atom. be.

Furthermore, at least one type of electron-accepting substance can be contained in the photosensitive layer for the purpose of improving sensitivity, reducing residual potential or fatigue during repeated use, and the like.

Electron-accepting substances that can be used in the photoreceptor of the present invention include:
For example, succinic anhydride, maleic anhydride, dibromaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride, 4
-Nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene,
1,3.5-trinitrobenzene, varanitrobenzonitrile, picryl chloride, quinone chlorimide, chloranil, chloranil, 2-methylnaphthoquinone, dichlorodicyanobarabenzoquinone, anthraquinone, dinitroanthraquinone, trinitrofluorenone, 9-fluorenylide - [dicyanomethylene malonodinitrile], polynitro-9-fluorenylidene [dicyanomethylene malonodinitrile], hyfuric acid, O-nitrobenzoic acid, 0-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluoro Benzoic acid, 5-nitrosalcylic acid,
3,5-dinitrosalicylic acid, phthalic acid, mellitic acid,
One or more types of other compounds with high electron affinity can be mentioned.

Among these, fluorenone type, quinone type, and CI.

Particularly preferred are benzene derivatives having electron-withdrawing substituents such as CN and NO2.

Furthermore, silicone oil or a fluorine-based surfactant may be present as a surface modifier. Further, an ammonium compound may be contained as a durability improver.

Furthermore, an ultraviolet absorber may be used. Preferred ultraviolet absorbers include nitrogen-containing compounds such as benzoic acid, stilbene compounds and derivatives thereof, triazole compounds, imidazole compounds, triazine compounds, coumarin compounds, oxadiazole compounds, thiazole compounds and derivatives thereof.

Examples of binder resins that can be used for the constituent layers of the photoreceptor include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, polyester resin, alkyd resin, polycarbonate resin, and melamine resin. , addition polymer resins such as methacrylic resins, acrylic resins, polyvinylidene chloride, and polystyrene, polyaddition resins, polycondensation resins, copolymer resins containing two or more of these repeating units, vinyl chloride-acetic acid Insulating resins such as vinyl copolymer resins, styrene-butadiene copolymer resins, vinylidene chloride-acrylonitrile copolymer resins, etc.
Further examples include polymeric organic semiconductors such as N-vinylcarbazole.

The above binders can be used alone or as a mixture of two or more.

As a binder for the protective layer provided as necessary,
Volume resistance 10 Ω・1 or more, preferably 1010 Ω・
A transparent resin having a resistance of 1 or more Ω, more preferably 10 Ω, is used. Further, the binder may be a resin that is cured by light or heat, and examples of the resin that is cured by light or heat include thermosetting acrylic resin, epoxy resin, urethane resin, urea resin, polyester resin,
Examples include alkyd resins, melamine resins, photocurable cinnamic acid resins, and copolymerized or condensed resins thereof, as well as all other photocurable or thermosetting resins used in electrophotographic materials. If necessary, the protective layer may contain less than 50% by weight of a thermoplastic resin for the purpose of improving processability and physical properties (preventing cracks, imparting flexibility, etc.). Such thermoplastic resins include, for example, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polycarbonate resin, or copolymer resins thereof, and poly-N-vinylcarbaso resin.
All of the thermoplastic resins used in electrophotographic materials, such as polymeric organic semiconductors such as y, etc., can be used.

The carrier generation layer can be provided by the following method.

(a) A method in which a binder and a solvent are added to a carrier-generating substance, mixed and dissolved, and a solution is applied.

(b) A method in which a carrier-generating substance, etc. is made into fine particles in a dispersion medium using a ball mill, a homomixer, a sand mill, an ultrasonic disperser, an attritor, etc., and a binder is added, mixed and dispersed, and the resulting dispersion is applied.

Dispersing the particles under the action of ultrasound in these methods allows for homogeneous dispersion.

Further, the carrier transport layer can be formed by applying and drying the above-mentioned carrier transport substance alone or by dissolving and dispersing it together with the above-mentioned binder resin.

In this case, when a carrier transport substance is contained in the carrier generation layer, the carrier transport substance is dissolved or dispersed in the solution (a) or the dispersion liquid (b) in advance, that is, in the carrier generation layer. There is a method of adding a carrier transport substance. In this case, it is preferable that the amount of the carrier transport substance added is within the range of 1 to 100 parts by weight per 100 parts by weight of the binder. Alternatively, there is a method in which a solution containing a carrier transport substance is applied onto the carrier generation layer, and the carrier generation layer is swollen or partially dissolved to diffuse the carrier transport substance into the carrier generation layer. When this method is adopted, it is not necessary to add a carrier transporting substance to the carrier generation layer as described above, but the above-mentioned Niga method may be carried out at the same time.

As the solvent or dispersion medium used for forming the layer, n
-butylamine, diethylamine, ethylenediamine,
Isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone,
Benzene, toluene, xylene, chloroform, 1,2
- Dichloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide and the like.

The photosensitive layer, undercoat layer, intermediate layer, protective layer, etc. can be provided by, for example, blade coating, dip coating, spray coating, roll coating, spiral coating, or the like.

The conductive substrate can be formed by applying a conductive thin layer made of a metal plate, a metal drum, a conductive polymer, a conductive compound such as indium oxide, or a metal such as aluminum, palladium, or gold to paper by means such as coating, vapor deposition, or lamination. , a material provided on a substrate such as a plastic film is used.

Next, preferred embodiments of the present invention will be described.

FIG. 2 is a schematic diagram of the configuration of an example of a recording device that implements the method of the present invention, FIG. 3 is a diagram of a schematic configuration of a laser beam scanner for image exposure, and FIG. 4 is a partial cross-section diagram of an example of a developing device. FIG. 5 is a flow chart for implementing the method of the present invention.

In the apparatus shown in FIG. 2, 23 is a drum-shaped image carrier which has a photosensitive layer made of the above-mentioned organic photoconductive substance and rotates in the direction of the arrow; 22 is a main charger that uniformly charges the surface of the image carrier 23; 24 is an image exposure device, and 15 is a developing device. 20 is a pre-transfer exposure lamp provided as necessary to facilitate the transfer of the toner image formed on the image carrier 23 onto the recording medium P, 21 is a transfer device, and 19 is a corona discharger for separation. , 12
is a fixing device that fixes the toner image transferred to the recording medium P. Reference numeral 13 has a static eliminator consisting of one or a combination of a static eliminator lamp and a corona discharger for static elimination, and 14 has a cleaning blade or a fur brush for removing residual toner on the surface of the image carrier 23 after the image has been transferred. It is a cleaning device.

When the image exposure is performed using a semiconductor laser, in the case of a recording device that uses a drum-shaped image carrier 23 like the recording device shown in FIG. 2, the image exposure 24 is performed using a laser beam scanner as shown in FIG. 3. Preferably.

The operation of the laser beam scanner shown in FIG. 3 will be described next.

The laser beam generated by the semiconductor laser 41 is transmitted to a polygon mirror 43&c rotated by a drive motor 42.
It is rotated and scanned by the mirror 45 through the fa lens 44.
The light path is bent by the light beam and projected onto the surface of the image carrier 23 to form a bright line 46.

Reference numeral 47 is an index lens for detecting the start of beam scanning, and reference numerals 48 and 49 are cylindrical lenses for correcting the inclination angle. Reflecting mirrors 50a, 50b, and 50C form a beam scanning optical path and a beam detection optical path.

When scanning is started, the beam is detected by the index sensor 47, and modulation of the beam by a signal is started by a modulation section (not shown). The modulated beam is applied to the image carrier 2 which is uniformly charged in advance by a charger 22&C.
3. Scan above. A latent image is formed on the drum surface by the main scanning by the laser beam 51 and the sub-scanning by the rotation of the image carrier 23.

Further, in a recording apparatus in which the image carrier can take a flat state such as a belt shape, the image exposure can be a flash exposure.

As the developing device 15, one having a structure as shown in FIG. 4 is preferably used. In FIG. 4, the developer De is conveyed in the direction of arrow G as the magnetic roll 62 rotates in the direction of arrow F and the sleeve 61 rotates in the direction of arrow G. Developer D
e is the thickness t due to the spike control blade 63 during conveyance.
is regulated.

The spike control blade 63 is made of an elastic metal plate and has a sleeve 610.
Press the surface to control the thickness of the developer being transported. Stirring blocks 17 and -65 are provided in the developer reservoir 66 to sufficiently stir the developer De, and when the developer De in the developer reservoir 66 is consumed, the toner supply roller 68 is turned off. Toner hopper 67 by rotating
Toner T is replenished from. A DC power supply 69 that applies a developing bias to the sleeve 61 and a protective resistor 70 are connected in series. Further, the sleeve 61 and the image carrier 23 are arranged facing each other with a gap d in between, and the developer comes into contact with the image carrier 23 in the development area E, as shown in t)d.

In the figure, the developing sleeve 61 and the magnet body 62 are indicated by the arrow G-
Although it is shown that the developing sleeve 61 rotates in the F direction, even if the developing sleeve 61 is fixed, the magnet body 62 is fixed, or the developing sleeve 61 and the magnet body 62 rotate in the same direction. It may be five. When the magnet body 62 is fixed, normally, in order to make the magnetic flux density of the magnetic pole facing the image carrier 23 larger than the magnetic flux density of other magnetic poles, the magnetization is strengthened or a magnetic pole of the same or different polarity is used. The two magnetic poles may be placed close to each other.

In the above-described apparatus, according to the present invention, one of the electrostatic latent images
Charge it so that V voltage is 400 to 900V, and then turn it on.
) During reverse development 1V111-IVDol = 0 to 20
Set it to 0V. However, v. is a DC bias voltage applied to the sleeve 61 as a developer transport carrier facing the image carrier 23. It is preferable to superimpose an AC bias voltage on the DC bias voltage. At this time, the effective value of the AC bias voltage is preferably 0.5 kV to 4 kV, and 0.5 kV to 4 kV.
1 KHz to IMk is preferred.

The method of the present invention as shown in FIG. 5 can be carried out using the recording apparatus as described above.

Figure 5 shows that an electrostatic image is formed by the electrostatic image formation method in which the image exposure area has a lower potential than the background area, and development charges the electrostatic image to the same polarity as the background area potential. The example shown in FIG. 5 when the recording apparatus shown in FIG. 2 is used will be explained.

First, the surface of the image carrier 23 in an initial state, which has been neutralized by the static eliminator 13 and cleaned by the cleaning device 14 and has a potential of 0, is uniformly charged by the charger 22. Image exposure 24 is projected onto the charged surface to perform image exposure such that the potential of the electrostatic image portion becomes approximately O, and the obtained electrostatic image is developed by a developer 15 (toner T)K.

The image forming method of the present invention can be applied to various light sources such as a nitrogen lamp, a tungsten lamp, an LED (light emitting diode), a gas laser such as helium-neon, argon, helium-cadmium, etc., and a semiconductor laser.

The image forming method of the present invention has a wide variety of applications such as electrophotographic copying machines and printers.

E. Examples Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited thereby, and of course includes other embodiments with various modifications.

<Synthesis of phthalocyanine compound> First, prior to the examples, a synthesis example of a metal-free phthalocyanine compound A having the properties shown in FIGS. 6 and 7, a synthesis example of a τ-type metal-free phthalocyanine compound, and a synthesis example of titanyl phthalocyanine. shows.

(Synthesis example of metal-free phthalocyanine compound A) 50Ii of lithium phthalocyanine is added to 600 dK of concentrated sulfuric acid with sufficient stirring at 0°C. The mixture is then stirred at this temperature for 2 hours.

The resulting solution is then filtered through a coarse sintered glass funnel and poured slowly into 4 liters of ice and water with stirring. After standing for several hours, the mixture is filtered and the resulting mass is washed with water until neutral. The mass is then finally washed several times with methanol and dried in air. This dried powder is 24
It is extracted with an acetate in a time-continuous extractor and dried in air to give a blue powder.

In the above the precipitation is repeated to ensure a salt residue for lithium. A blue powder of 30.51i was thus obtained. The X-ray diffraction pattern of the obtained product was consistent with the X-ray diffraction pattern of the α-ya phthalocyanine compound described in previously published materials.

The metal-free α-type phthalocyanine compound 30II thus obtained at 5 Kt was charged into a porcelain ball mill with an internal volume of 900 m filled with 13/16 inch diameter balls and milled at about 80 rIm for 164 hours. Thereafter, 200 mJ of an organic solvent such as tetrahydrofuran or 1,2-dichloroethane was added to the ball mill, and milling was carried out again for 24 hours. The organic solvent was removed from the dispersion after milling and the dispersion was dried to obtain a thermometallic phthalocyanine compound No. 28,211. (Synthesis example of τ-type metal-free phthalocyanine) A metal-free phthalocyanine compound produced by α (Monolite Fast Pull GS manufactured by ICI) was extracted and purified three times with heated dimethyl formaldehyde.

Through this operation, the purified product was transferred to the β form. Next, a portion of this β-type metal-free 7-talocyanine compound is dissolved in concentrated sulfuric acid, and this solution is poured into ice water to re-precipitate.
It was transferred to α type. This reprecipitate was washed with aqueous ammonia, methanol, etc., and then dried at 10°C. Next, the α metal-free phthalocyanine compound purified above was placed in a sand mill together with a grinding aid and a dispersant, and the temperature was 100±20°C.
The mixture was kneaded for 15 to 25 hours. This operation changed the crystal form to 7.
After confirming that it has transferred to the surface, take it out from the container, thoroughly remove the grinding aid and dispersant with water and methanol, etc., and dry it to obtain blue crystals of τ-type metal-free phthalocyanine with a clear bluish tinge. Ta.

(Synthesis example of titanyl phthalocyanine) A mixture of phthalodinitrile 401i, titanium tetrachloride 1811, and α-chloronaphthalene 500id was heated and stirred at 240 to 250° C. for 3 hours under a nitrogen stream to complete the reaction. Thereafter, it was filtered to obtain the product dichlorotitanium phthalocyanine. A mixture of the obtained dichlorotitanium phthalocyanine and 300 tnl of concentrated ammonia water was heated under reflux for 1 hour to obtain titanyl phthalocyanine 1811, which was the target product. The product was thoroughly washed with acetone using a Soxhlet extractor.

Mass spectrometry analysis of this product revealed that the main component was titanyl phthalocyanine (M 576) and a small amount of chlorinated titanyl phthalocyanine (M 610).

<Manufacture of Photoreceptors> Photoreceptors A to M of Examples and photoreceptors a to d of Comparative Examples were manufactured by performing 5&C as described below. That is, the manufacturing procedure for each photoreceptor is common.

A charge blocking layer coating solution obtained by dissolving the predetermined binder resin 2ON shown in Table 2 in 1000au of tetrahydrofuran was used as rKONIcA U-Bix1550.
Aluminum base drum (diameter 8
0) K dip was applied to form a charge blocking layer of a predetermined thickness.

Next, a predetermined amount of carrier generating substance (CGM) shown in Table 2 was prepared.
) was ground in a magnetic ball mill for 18 hours at 4 Or-, then 1,300 J (manufactured by Yojin Kasei Co., Ltd.) of polycarbonate "Panlite" was mixed with 1,2-dichloroethane (1,000 g).
- was added and dispersed for another 24 hours, and the resulting carrier generation layer coating solution was dip coated on the charge blocking layer, and the PZB ratio (carrier generation substance/weight of binder) shown in Table 2 was applied. A carrier generation layer having a ratio) was obtained.

However, for the photoreceptor cK of the comparative example, a charge blocking layer was not provided, and a carrier generation layer was formed directly on the conductive substrate.

Furthermore, 112.5 g of the carrier transport substance shown in (5) below and 150 g of polycarbonate resin "Europine Z-200J (manufactured by Mitsubishi Gas Chemical Co., Ltd.) were mixed with 1,2-dichloroethane 1
0001117! The resulting solution was dip-coated onto the carrier generation layer and dried at a temperature of 90° C. for 1 hour to form a carrier transport layer, resulting in a photosensitive layer having a thickness of about 20 μm.

As described above, each of the photoconductors A to M and a to d, each having an individual configuration and prescription, is manufactured using a common manufacturing procedure.
was manufactured.

That is, in each photoreceptor, the material of the charge blocking layer,
The carrier-generating substances and the like are changed from each other.

CGM (1) Metal-free phthalocyanine compound A CGM (2) τ-type metal-free phthalocyanine CGM (3) Said titanyl phthalocyanine CGM (4) Carrier transport substance (5) Resin (S) Polyester resin "Vylon 2000J (manufactured by Toyobo Co., Ltd.) Resin (T) Vinyl chloride-vinyl acetate copolymer resinrVYH)tJ(
(manufactured by Union Carbide) Resin (X) Polyvinyl butyral rXYHLJ (manufactured by Union Carbide) Resin (Y) Polyvinyl butyral resin "S-LEC BH-3J (manufactured by Tanemizu Kagaku Kogyo) Resin (Z) Polyvinyl formal resin "Tenka Formal #30J
(manufactured by Denki Kagaku Kogyo Co., Ltd.) Example 1 and Comparative Example 1 Each of the photoreceptors of the Example and Comparative Example was tested using rKON ICA U-Bix 1550J (manufactured by Denki Kagaku Kogyo Co., Ltd.), which uses a semiconductor laser as a light source.
:ff manufactured by Nirikisha) installed on a modified machine, vH is 1600±1
Adjust the grid voltage so that it is 0 (V)K, and set the developing via 7! Reverse development was carried out at f-480 (V), and the black spots on the white background part of the copied image, the image density of the black background part (corresponding to the white background part of the original image) 1) max, the coating properties of the carrier generation layer, and the image defects were checked. evaluated.

In addition, the evaluation of Kuropochi was performed using the image analysis device "Omnicon 30".
00 type" (manufactured by Takasu Seisakusho Co., Ltd.) to measure the particle size and number of black spots, and the number of black spots with a diameter of 0.05 mm or more was 1.
Judgment was made based on the number of pieces per cIla.

The criteria for evaluating black spots are as shown in Table-IK.

Note that if the black spot determination result is ◎, ○, or Δ, it is practical, but if it is × or XX, it is not suitable for practical use.

Regarding the good or bad coating properties of the carrier generation layer, please refer to the following 5.
[did. That is, the relative falling speed of the liquid level during dip coating of the carrier generation layer (CGL) was kept constant (0.5 cm).
/5ec) and 100cd when applying CGL!
Measure the amount of CGM attached per (ldgo), and this is 2*
/dm'' without grooves was considered to be a coating failure.

Further, regarding image defects, presence or absence of density unevenness in the solid black portion of the copied image was visually confirmed, and regarding agglomeration of the carrier generation layer, density unevenness of the carrier generation layer was visually confirmed.

The results of black spot evaluation on each photoreceptor are shown in Section 2 below.

(The following is a margin, continued on the next page) From the results shown in Table 2, it is clear that when copying images are formed based on the image forming method of the present invention, black spots are significantly reduced, image density unevenness does not occur, and images are It can be seen that the density can be increased and uniform and high quality images can be obtained.

Example 2 and Comparative Example 2 Reverse development was performed in the same manner as in Example 1 (or Comparative Example 1) under the conditions shown in Cloth-3 below, and black spots, image density of the black background part of the copied image, /Dmax, and carrier adhesion were And I saw fog. However, regarding carrier adhesion, O represents no adhesion, and x represents occurrence of adhesion.

(Margin below, continued on next page) Table-3 After copying rice 10 times [it became impossible to charge up to 950V].

From this result, the following is clear.

For photoconductor A: If IVHl < 400V, the image density is insufficient.

IVHI-1vDO1> 200vteha # y') y
Attached tr occurred.

IVHI　IVDOI　(OV Teha full surface capri generation.

For photoconductor d: Black spots occur and the image density is insufficient.

[Brief explanation of the drawing]

1 to 7 show embodiments of the present invention, FIG. 1 is a $#i sectional view of a photoreceptor used in the present invention, FIG. 2 is a schematic diagram of the configuration of an image forming apparatus, Figure 3 is a schematic diagram of the configuration of a laser beam scanner for self-exposure, Figure 4 is a sectional view of the main parts of a developing device, Figure 5 is a flowchart showing the process of image formation, and Figure 6 is a diagram of a thermal metal phthalocyanide compound. X@Diffraction Spectrum Figure 7 is a near-infrared absorption spectrum diagram of a metal-free phthalocyanine compound. FIG. 8 is a partial sectional view of a conventionally used photoreceptor. In addition, in the symbols shown in the drawings, 1... Conductive substrate 4... Carrier transport layer 6... Carrier generation layer 7... ......Charge blocking layer 8...
...Photosensitive layer 12...Fuser 13...Static eliminator 14...Cleaning device 15...
...Developer 20...Pre-transfer exposure lamp 21...
...Transfer device 22...Charger 23...Image carrier 41...Racer 43... ...Mirror scanner 44...
...F-θ lens for imaging 48.49...Cylindrical lens 51...Laser beam 61...Modern sleeve 62... ...... Magnet body 63 ...... Layer thickness regulation blade 69 ...
. . . Bias power supply 70 . . . Protection resistor. Representative Patent Attorney Hiroshi Aisaka Figure 1 Figure 5 Figure 8 2θ (JI 11 degrees) husband ,
4.7; 1. Indication of the case 1986 Patent Separate Section No. 317840 2. Name of the invention Image forming method 3. Person making the amendment Relationship to the case Patent applicant address 1-26 Nishi-Shinjuku, Shinjuku-ku, Tokyo 2nd name name
(127) Konica Co., Ltd. 4, Agent address: FINH Building, 2-4-11 Shibasaki-cho, Tachikawa-shi, Tokyo Column 6 of the detailed description of the invention in the specification, Contents of amendment (1), Line 1, page 19 of the specification the eyes
1- or more-

Claims (1)

[Claims] 1. An image forming method using a photoreceptor having a photosensitive layer having a carrier transport layer provided on a carrier generation layer, (a) a phthalocyanine compound is contained as a carrier generation substance. (b) using a photoreceptor having a carrier generation layer and a charge blocking layer provided between the carrier generation layer and the conductive substrate and containing polyvinyl butyral and/or polyvinyl formal; The absolute value of the potential charged on the body is 400V ~ 9
After applying a charge of 00 V, an electrostatic latent image is formed by exposure, and then the voltage is 0 to 200 V lower than the absolute value of the charged potential.
An image forming method characterized in that reversal development of the electrostatic latent image is performed by applying a DC bias voltage having a low absolute value of V.