JPH01206358A - Image forming method - Google Patents

Abstract

PURPOSE:To prevent generation of interference fringe-type unequal densities (moires) and to obtain a high-quality image by providing a light scattering layer incorporated with a binder material and titanium oxide which is not subjected to a conducting treatment between a carrier generating layer and conductive base body. CONSTITUTION:The photosensitive body having the light scattering layer 7 provided between the carrier generating layer 6 and the conductive base body 1 and incorporated with the binder material and the titanium oxide which is not subjected to the conducting treatment is electrostatically charged and is then irradiated with laser light, by which an electrostatic latent image is formed thereon in the image forming method using the photosensitive body having the photosensitive layer 8 provided with a carrier transfer layer 4 on the carrier generating layer 6. Namely, the light entering the inside of the light scattering layer is scattered by the dispersion state of the titanium oxide and the phases of the exit light from the photosensitive layer 8 are not longer unified so that interferences are no longer generated. The moires are thereby prevented and the high-quality image having the uniform density is formed.

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 the photoreceptor is charged, an electrostatic latent image is formed by exposure, and the electrostatic latent image is developed with toner, and then the visible Transfer and fix the image 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 not only has electrophotographic properties such as good charging characteristics, good sensitivity, and low dark decay, but also physical properties such as stiffness resistance, abrasion resistance, and moisture resistance after repeated use. It is also required to have good 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, poly-N-
Vinylcarbazole and 2.4.7-trinitro-9-
An organic photoreceptor having a photosensitive layer containing 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. 7 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 negatively charged, it is possible to use a hole-transporting photoconductive material with good properties. This is advantageous in terms of sensitivity, etc.

In contrast, few electron-transporting materials have excellent properties or are carcinogenic, so they cannot be used. 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 photoreceptor described above, carrier injection from the conductive substrate or lower layer side tends to occur when negatively charged, as shown in FIG. 7, and as a result, the surface charge disappears microscopically, or It will decrease. Although the cause of such local carrier injection is not clear, it is thought to be due to defects or non-uniformity on the surface of the conductive substrate, non-uniformity in the charge generation layer, or the like.

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 reversal development, a toner image is formed on the exposed area (the area where the surface charge has disappeared, (L)), and the unexposed area is In the area (portion where the surface charge is retained, ■H), no ■ tone image is formed.

However, in the reversal development method, when 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, resulting in so-called fog. It becomes an image. This kind of fog is different from normal fog, and is a phenomenon that occurs when the surface charge on the photoreceptor microscopically disappears or decreases during reversal development, as described above, and is called "black spots." 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.

When developing an electrostatic latent image using the photoreceptor described above using the regular development method, the surface charge disappears and toner does not adhere to the reduced area and is not developed, so that the so-called Image defects called white spots occur.

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 4 and suppress carrier injection to the photoreceptor surface, but in this photoreceptor, there is a decrease in photosensitivity, an increase in residual potential, and an increase in IVLl. This leads to a decrease in lV=1 stability during repeated use and a decrease in temperature characteristics, and at low temperatures, the photoreceptor characteristics are greatly deteriorated, such as an increase in 1L1.

Furthermore, in recent years, semiconductor laser light sources have been used in electrophotographic copying methods, which are inexpensive, compact, and capable of direct modulation.

Gallium-aluminum-arsenic (Ga-Al-As) light emitting devices, which are currently widely used as semiconductor lasers, have an oscillation wavelength of about 750 nm or more. In order to obtain an electrophotographic photoreceptor with high sensitivity to such long wavelength light,
Many studies have been made in the past. For example, a method was considered to add a new sensitizer to a photosensitive material such as selenium or cadmium sulfide, which has high sensitivity in the visible light region, to extend the wavelength to a longer wavelength. There are problems with practical application due to insufficient environmental resistance (and toxicity).In addition, the sensitivity of many known permeable photoconductive materials is usually limited to the visible light region of 700 nm or less. Since there are few materials that have sufficient sensitivity in longer wavelength ranges, it has been difficult to use them in laser printers that use semiconductor laser light sources that are expected to be highly reliable.

Furthermore, for example, using a photoreceptor as shown in FIG.
When images are formed by irradiating body laser light, density unevenness in the form of interference fringes called moiré occurs in halftone images. Therefore, there has been a need for an image forming method that can eliminate moiré.

C1 Process leading to the invention In view of the above circumstances, the present inventor has developed an image forming method that can prevent the occurrence of moiré when using a laser light source.
Various considerations were made.

For example, it is possible to appropriately roughen the surface of the conductive substrate to prevent interference. However, this method significantly increases black spots especially in reversal development, making it impractical.

On the other hand, it is also possible to prevent interference by increasing the thickness of the carrier generation layer and increasing the absorbance within the carrier generation layer. However, such photoreceptors have a drawback in that their characteristics are insufficient, particularly in that their temperature and humidity characteristics are significantly deteriorated.

That is, when regular development is performed, under high temperature conditions, dark decay increases and the charging potential (■0, black paper potential) decreases, resulting in insufficient image density. On the other hand, at low temperatures, photocarriers are 1-ramped in the carrier generation layer, resulting in a decrease in photosensitivity and an increase in residual potential, resulting in fog on the image. On the other hand, when reversal development is performed, fog occurs on the image at high temperatures, and image density becomes insufficient at low temperatures. Furthermore, during reversal development, the occurrence of black spots becomes noticeable, which is very inconvenient.

20 OBJECTS OF THE INVENTION An object of the present invention is to prevent the occurrence of 4 degree unevenness (moiré) in the form of interference fringes when using a laser light source and to obtain a uniform image in environments such as high temperature, high temperature, low temperature and low humidity. To provide an image forming method capable of obtaining a high-quality image with no fog and high image density even in the case of an image forming apparatus, and also capable of obtaining a high-quality image with significantly suppressed image defects such as black spots. be.

E2 Structure of the Invention The present invention provides an image forming method using a photoreceptor having a photosensitive layer in which a carrier transport layer is provided on a carrier generation layer. and a step of forming an electrostatic latent image by applying a charge to a photoreceptor having a light-scattering layer containing a binder substance and non-conductively treated titanium oxide, and then irradiating it with laser light. The invention relates to an image forming method.

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

In the present invention, a photoreceptor is used in which a light scattering layer containing a binder substance and titanium oxide that has not been subjected to conductive treatment is provided between a carrier generation layer and a conductive substrate, and a laser beam is applied onto the photoreceptor. A notable feature is that an electrostatic latent image is formed by irradiation with light.

That is, it is important that by employing a photoreceptor having such a configuration, the above-mentioned moiré (density unevenness in the form of interference fringes) can be prevented and images with uniform density can be formed.

The cause of interference fringe-like density unevenness on an image is not clear, but it is thought to be as follows.

As shown in FIG. 8, when the surface of the photoreceptor shown in FIG. enters the photosensitive layer 8, is reflected by the substrate surface 1a, and is emitted as emitted light 18. At this time, the refractive index of the photosensitive layer is n
, thickness d, wavelength λ of the semiconductor laser light, and assuming that the laser light 16 is incident perpendicularly to the photosensitive layer 8, the light 1
An optical path difference of (2nd-λ/2) occurs between the light 7 and the light 18. Since laser light is coherent, light 1
7 and the light 18, and when nd is an integral multiple of λ/2, the intensity of the reflected light is maximum, that is, the intensity of the light entering the carrier transport layer 4 is minimum (according to the law of conservation of energy) ), when nd is an odd multiple of λ/4, the reflected light is minimal, that is, the light entering the interior is i large. Incidentally, due to manufacturing reasons, d has an unavoidable local unevenness of about 1 μm. Since laser light is monochromatic and coherent, d
The above-mentioned interference condition changes corresponding to the unevenness in the location, and the amount of absorption of laser light in the carrier generation layer 6 becomes uneven in the location,
It is thought that this appears as interference fringe-like unevenness in the density of the solid image.

Note that in a normal copying machine, since the light source is not monochromatic light, the width of the density unevenness in the form of interference fringes varies depending on the wavelength, and is averaged out and cannot be seen.

In contrast, according to the present invention, a light scattering layer is provided between the conductive substrate and the photosensitive layer, and this light scattering layer contains a binder substance and titanium oxide that is not subjected to 'JQ treatment. Due to the dispersion state of titanium oxide, the light that enters the light scattering layer is scattered, and the phase of the light emitted from the photosensitive layer is no longer aligned. As a result, no interference occurs, and no local unevenness in the intensity of reflected light due to interference occurs.

For the above reasons, density unevenness in the form of interference fringes can be prevented.

Moreover, it is important that such laser printers solve the technical problems essential to such printers, while also having excellent temperature and humidity characteristics (environmental resistance characteristics), and being able to provide good images even under high temperature and high humidity conditions, as well as under low temperature and low humidity conditions. It is.

That is, since devices such as printers are used for long periods of time under various conditions, they are extremely often exposed to environments such as high temperatures, low temperatures, and low humidity. In this regard, it must be said that if the carrier generation layer itself was made thicker as described in the prior art section, it would lack practicality because it would result in insufficient image density and fog.

In contrast, according to the method of the present invention, the carrier generation layer itself may be a thin film, and dark decay does not increase under high temperature and high humidity conditions, and trapping of optical carriers can be suppressed under low temperature and low humidity conditions. Therefore, the image density can be made sufficiently high, and fog does not occur on the image.

Furthermore, another notable feature is that the light scattering layer also has a charge profking function for blocking charge injection.

That is, when a photoreceptor as shown in FIG. 7 is used, carriers (holes) injected from the base 1 side easily pass through the carrier generation layer 6, forming a carrier transport layer with high hole transport properties. 4 to the surface of the photoreceptor. In other words, the carrier generation layer 6 cannot function as a barrier to local carrier injection.

On the other hand, in the present invention, since the light scattering layer contains a binder substance and titanium oxide that has not been subjected to conductive treatment, it also has a charge blocking function as a result. Therefore, by providing the light scattering layer between the conductive substrate and the carrier generation layer, it is possible to provide a barrier against local carrier injection from the conductive substrate side.
Disappearance and reduction of surface charge due to local carrier injection can be prevented.

Therefore, especially when reversal development is performed, black spots do not occur on the image (and a high quality image without image defects can be obtained, which is a remarkable effect).

Note that even in regular development, the occurrence of white spots can be suppressed.

The charge blocking effect of such a light scattering layer will be explained in detail.

That is, the electrical resistance of the light scattering layer itself is kept high by the action of the binder material and the titanium oxide that has not been subjected to conductive treatment, and therefore carrier injection from the conductive substrate side can be effectively prevented. Here, suppose R? When using titanium oxide treated with , carrier injection may be blocked, black spots will appear on the image during reversal development, and the charge processing/7 king function cannot be developed.

On the other hand, the negative photocarriers generated within the carrier generation layer during light irradiation are transported within the light scattering layer by titanium oxide that has not been subjected to conductive treatment, and are thought to be transferred to the conductive substrate. Titanium oxide is a substance that has electron conductivity, and its action imparts electron conductivity to the light scattering layer itself. Therefore, the movement of the optical carrier becomes smooth, and it becomes possible to increase the optical intensity, reduce the residual potential during repeated use, and increase the image tmK, so that a high-quality image can be provided.

When the present invention is applied to the reversal development method, especially when applied to a printer, the text area (black background area) has a smaller area (that is, the exposed area is smaller) than the white background area, and the normal This method is advantageous in terms of preventing deterioration of the photoreceptor, etc., compared to the development method.

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 light scattering layer 7 interposed therebetween, and carrier generation I! A carrier transport layer 4 is provided on top of the carrier transport layer 6 . 8 indicates a photosensitive layer.

In the photoreceptor shown in Fig. 1, an intermediate layer having a pro-noking function may be provided between the carrier generation layer and the carrier transport layer. A protective PJ (protective film) may be formed on the body surface, 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, it is incorporated into the layer in the form of a pigment.

Regarding titanium oxide that has not been subjected to conductive treatment, "not conductive treated" generally means that the specific resistance is preferably 10'Ω·1 or more.

The titanium oxide is preferably granular with an average particle size of 1 tIm or less, and more preferably 0.1 to 0.4 μm.

Here, the above-mentioned "average particle size" may be measured by directly selectively counting with an electronic U4 microscope, or may be measured from particle size distribution using a laser beam or the like. It can also be calculated as a sphere from the specific surface area. Other known methods can also be used.

Titanium oxide may be subjected to treatments other than conductive treatment, and main treatment agents include aluminum, silicon, zinc, nickel, antimony, chromium, and the like.

As a pretreatment for titanium oxide, various ions existing as impurities can be washed away, or ion exchange treatment can be performed. In addition, the particle surface is treated with a coupling agent,
It is also possible to improve the dispersibility.

The specific product name is high purity titanium oxide rCR-E.
LJ, ultrafine titanium oxide rTTO-55", sulfuric titanium oxide rR-550J, rR-630", rR-6
80J, rR-670J, rR-580'', rR-78
0J, rA-100J, rA-220'', rW-10J
, chlorinated titanium oxide rCR-50'', rCR-60J,
rCR-60-24, rcR-67'', rCR-58J
(all manufactured by Ishihara Sangyo Co., Ltd.), etc. are exemplified.

The thickness of the light scattering layer is preferably 0.1 to 5 μm,
It is more preferable that the thickness be within the range of 0.5 to 2 μm. Also, in the light scattering layer, the content ratio (weight ratio) of titanium oxide that has not been subjected to conductive treatment and the binder substance is (1:1).
It is preferably within the range of 0) to (10:l).

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 2/1 to 1/3. If it is larger than the above range, black spots etc. will appear significantly or will be likely to appear. However, if the proportion of the carrier-generating substance is too small, the light intensity etc. will be rather reduced.

The thickness of the carrier generation layer is preferably 0.05 μm or more, and more preferably within the range of 0.2 to 0.5 μm.

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 lower due to the thinner film, and the stiffness resistance 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 preferably in the form of powder particles with an average particle size of 2 μm or less, preferably 1 μm or less, and more preferably 0.5 μm. preferable.

Further, in the carrier transport layer, the carrier transport substance preferably has excellent compatibility with the binder substance. As a result, turbidity and opacity do not occur even if the amount of the binder substance is increased, so the mixing ratio with the binder substance can be set at a very wide range. The layer is uniform and stable, resulting in better sensitivity and charging characteristics, and it is possible to use a photoreceptor that can form clear images with high intensity. Furthermore, especially when used in repeated transfer type electrophotography, it is possible to achieve the effect that fatigue deterioration is less likely to occur.

Examples of binder substances that can be used in the light scattering layer and the photosensitive layer include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin,
Epoxy resin, polyurethane resin, polyester resin,
Addition polymerization type resins such as alkyd resins, polycarbonate resins, silicone resins, melamine resins, methacrylic resins, acrylic resins, polyvinylidene chloride, polystyrene, polyaddition type resins, polycondensation type resins, and two or more of these repeating units copolymer resins containing vinyl chloride-vinyl acetate copolymer resins, insulating resins such as vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, styrene-butadiene copolymer resins, vinylidene chloride-acrylonitrile copolymers Examples include polymeric organic semiconductors such as polymeric resins and N-vinylcarbazole.

In addition to the above-mentioned binder resin, the light scattering layer may also contain, for example, polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, casein, N-alkoxymethylated nylon, starch, and the like.

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 108Ω・(1) or more, preferably 1010Ω
- A transparent resin having a resistance of 1 or more Ω·cm, more preferably 10 −3 Ω·cm or more 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, silicone resin, epoxy resin, urethane resin, urea resin,
Examples include polyester resins, 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 quality of the product (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, silicone resin, or copolymer resins thereof, such as vinyl chloride-vinyl acetate-maleic anhydride. Copolymer resins, polymeric organic semiconductors such as poly-N-vinylcarbazole, and other thermoplastic resins used in electrophotographic materials can all be used.

As the carrier generating substance (CC, M), any inorganic pigment or organic pigment can be used as long as it absorbs electromagnetic waves and generates free carriers. Examples of CGM include the following.

(1) Amorphous selenium, trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, cadmium sulfide, cadmium selenide, cadmium selenide sulfide, mercury sulfide, lead sulfide,
Inorganic pigments such as zinc oxide and amorphous silicon (2) Azo pigments such as monoazo pigments, polyazo pigments, metal complex azo pigments, pyrazolone azo pigments, stilbene azo and thiazole azo pigments (3) Anthraquinone derivatives, anthorone derivatives , dibenzpyrenequinone derivatives, vilantrone derivatives,
Anthraquinone or polycyclic quinone pigments such as violanthrone derivatives and isoviolanthrone derivatives (4) - (indigoid pigments such as ndigo derivatives and thioindigo derivatives) (5) diphenylmethane pigments, triphenylmethane pigments, xanthine pigments and acridine pigments Carbonium pigments such as (6) Quinoneimine pigments such as azine pigments, oxazine pigments and thiazine pigments (7) Methine pigments such as cyanine pigments and azomethine pigments (8) Quinoline pigments (9) Nitro pigments (10) Nitroso Pigments (11) Benzoquinone and naphthoquinone pigments (12)
Naphthalimide pigments (13) Perylene pigments such as bisbenzimidazole 3J'JHL (14) Fluorenone pigments (15) Squarylium pigments (16) Azulenium compounds (17) Perylene pigments such as perylenic anhydride and perylenic acid imide Examples of preferable azo compounds and polycyclic quinone pigments will be shown below.

(I~2) (I-5) A-N=N-Ar'-CH=CH-A r2-N=N-
AA-N = N-A r'-CI = CI(
-A r''-CH=CI--A r3-N=N-
A (1-8> A=N=N-A r'-N=N-A r"-N=N-A
A-N=N-Ar'-N=N-Ar2-N=N --A
r3-N=N-A -A r'-N=N-A [However, in each of the above formulas, Ar', Ar'' and Ar'': each substituted or unsubstituted carbocyclic aromatic ring group, R1, R2, R3 and R4: Each of them is an electron-withdrawing group or a hydrogen atom, and RI and R4 are each an electron-withdrawing group (one is an electron-withdrawing group such as a cyano group, , <However, R6 and R7 are each a hydrogen atom or a substituted or unsubstituted alkyl group, R8 is a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group>, Y is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, unsubstituted alkyl group, alkoxy group,
Carboxyl group, sulfo group, substituted or unsubstituted carbamoyl group, or substituted or unsubstituted sulfamoyl group (however, when m is 2 or more, mutually different groups may be used), Z is substituted or unsubstituted Atom groups necessary to constitute a carbocyclic aromatic ring or a substituted or unsubstituted heterocyclic aromatic ring, R5 is a hydrogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted carbamoyl group, A carboxyl group or an ester group thereof, A and 4 are substituted or unsubstituted aryl groups, n is an integer of 1 or 2, and m is an integer of 0 to 4. )] In addition, polycyclic quinone pigments of the following general formula (II) group are also CGM
Can be used as

General formula [■]: (However, in this formula,
represents an integer of 0 to 4, and q represents an integer of 0 to 6. ) For squarylium pigments, see JP-A-60-25855.
There is a description in Publication No. 0, etc.

For azulenium compounds, see Japanese Patent Application No. 62-2511.
It is described in the specification of No. 88.

The carrier transport substances used in the present invention include carbazole derivatives, oxazole 3% i forms, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidasilone derivatives, imidazolidine Pg forms, bisimidazolidine derivatives,
styryl compound, hydrazone compound, pyrazoline derivative, oxacilone derivative, benzothiazole W form, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative 4 form, phenazine 33,1 form,
aminostilbene derivatives, triarylamine derivatives,
Phenylenediamine derivatives, stilhen derivatives, poly-
It may be one or more selected from N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, and the like.

Specific examples of such carrier transport substances are disclosed in Japanese Patent Application No. 1983.
-195881. The general formula is listed below.

The following general formula Cm) or (IV
) styryl compounds can be used.

-Mathical formula [■]: (However, in this -math formula, R9, RIG, ii represents a substituted or unsubstituted alkyl group, or an alkyl group, and the substituents include an alkyl group, an alkoxy group, a substituted amino group, A hydroxyl group, a halogen atom, or an aryl group is used.

ArS, Ar6: represents an i-substituted or unsubstituted aryl group, and as a substituent, an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, or an aryl group is used.

R item R12: substituted or unsubstituted aryl group,
It represents a hydrogen atom, and examples of substituents include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, and an aryl group. ) General formula [■]: However, in this formula, R13: substituted or unsubstituted aryl group, R14: hydrogen atom, halogen atom, substituted or incompatible alkyl group, alkoxy group, amino group, substituted amino group , hydroxyl group, R15: represents a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group. ) In addition, the following general formulas (V) and (V
The hydrazone compounds of l), (Vla), (VIb) or [■] can also be used.

General formula [■]: (However, in this formula, RI6 and R17: each a hydrogen atom or a halogen atom, RIB and R'9 = each a substituted or unsubstituted aryl group, Ar7: an i-substituted or unsubstituted arylene group represents.

) General formula [■] : (However, in this formula, R20 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted carbazolyl group, or a substituted or unsubstituted heterocyclic group, Rz+, RZ2 and R23 : Represents a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.) General formula (VIa): ^... (However, in this formula, R24: methyl group, ethyl group, 2-hydroxyethyl group or 2-chloroethyl group, R25: methyl group, ethyl group, benzyl group or phenyl group, R26: methyl group, ethyl group, benzyl group or phenyl group.

- Formula [: VIbl: (However, in this - format, R2? is a substituted or unsubstituted naphthyl group; R28 is a substituted or unsubstituted alkyl group,
Aralkyl group or aryl group; R29 is a hydrogen atom, an alkyl group, or an alkoxy group; R30 and R'' are substituted or unsubstituted alkyl groups, aralkyl groups, or groups that are the same or different from each other.) - Numerical formula [■]: (However, in this - format, R32: substituted or unsubstituted oryl group or substituted or unsubstituted heterocyclic group, R33: hydrogen atom, substituted or unsubstituted alkyl group, or substituted or a device-substituted aryl group, Q: represents a hydrogen atom, a halogen atom, an alkyl group, a substituted amino group, an alkoxy group, or a cyano group, sho or an integer of 1.) In addition, as a carrier transport substance, the following general formula [■ ] Pyrazoline compounds can also be used.

- Formula [■]: [However, in this - format, 1:0 or 1, R'' and R35; substituted or unsubstituted 7-aryl group, R
36: Substituted or unsubstituted aryl group or heterocyclic group, R3ff and R38: Hydrogen atom, alkyl group having 1 to 4 carbon atoms, or substituted or device-substituted aryl group or aralkyl group (However, R37 and R3a are both It is not a hydrogen atom (and when the above ! is 0, R'' is not a hydrogen atom.) Furthermore, an amine derivative of the following general formula (IX) can also be used as a carrier transporting substance.

General formula [■]: (However, in this form, Ar8.Ar9 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.

A r I Q: substituted or unsubstituted phenyl group,
Represents naphthyl group, anthryl group, fluorenyl group, and heterocyclic group, and substituents include alkyl group, alkoxy group, halogen atom, hydroxyl group, aryloxy group, aryl group, amino group, nitro group, piperidino group, morpholino group, and naphthyl group. Anthryl groups, anthryl groups and substituted amino groups are used. However, an acyl group, an alkyl group, an aryl group, or an aralkyl group is used as a substituent for the substituted amino group. ) Furthermore, a compound of the following general formula (X) can also be used as a carrier transport substance.

General formula [X]: (However, in this - format, A r l + represents a substituted or unsubstituted arylene group, R39, R", R" and R42: substituted or unsubstituted alkyl group, substituted or unsubstituted (represents a substituted aryl group or a substituted or unsubstituted aralkyl group) Furthermore, a compound of the following general formula (XI) can also be used as a carrier transport substance.

General formula (XI): [However, in this formula, R41, R'', R'' and Rsb are each a hydrogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, a benzyl group, or Aralkyl group, R4? and R48 are each a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, or an aralkyl group (provided that R4'l and R411 are jointly to form a saturated or unsaturated hydrocarbon ring having 3 to 10 carbon atoms.) R49, R5O, R5I and R52 each represent a hydrogen atom, a halogen atom, a hydroxyl group, or a substituted or unsubstituted alkyl group. group, cycloalkyl group, alkenyl group, aryl group, aralkyl group, alkoxy group, amino group, alkylamino group or 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 by discharge, and can prevent residual potential upper limit 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 four polymeric organic hemiforms, 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. .

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,
Tetrabromo phthalic anhydride, 3-nitro phthalic anhydride,
4-nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, 0-dinitrobenzene, m-dinitrobenzene, 1.3.5-) dinitrobenzene, varanitrohen dinitrile , picryl chloride, quinone chlorimide, chloranil, brumanil, 2-methylnaphthoquinone,
dichlorodicyanobara benzoquinone, anthraquinone,
Dinitroanthraquinone, trinitrofluorenone, 9
-Fluorenylidene [dicyanomethylene malonodinitrile], polynitro-9-fluorenylidene [dicyanomethylene malonodinitrile], picric acid, 0-nitrobenzoic acid, p-di-benzoic acid, 3.5 -Dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3.5-dinitrosalicylic acid, phthalic acid, mellitic acid, and one or more kinds of other compounds with high electron affinity can be mentioned.

Among these, fluorenone type, quinone type, CI! ,
Particularly preferred are benzene derivatives having electron-withdrawing substituents such as CN and No.

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.

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

(a) A method in which a binder and a solvent are added to titanium oxide that has not been subjected to conductive treatment or a carrier-generating substance, and a mixed solution is applied.

(b) Titanium oxide or carrier-generating substances that have not been subjected to conductive treatment are made into fine particles in a dispersion medium using a ball mill, homomixer, sand mill, ultrasonic disperser, attritor, etc., and Ha Ingu is added to the mixture and dispersed. method of applying a dispersion liquid.

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 melting 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 Ba Ingu. 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 it is also possible to carry out the above three methods at the same time.

As the solvent or dispersion medium used for forming the layer, n
-butylamine, diethylamine, ethylenediamine,
Isopropanolamine, triethanolamine, 1-lyethylenediamine, 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. For example, blade coating is suitable for providing layers of a few μm.

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. 5 and 6 are flow charts for implementing the method of the present invention, respectively.

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; 19 is a separation corona discharger; 12
is a fixing device that fixes the toner image transferred to the recording medium P. Reference numeral 13 denotes a static eliminator consisting of one or a combination of a static eliminator lamp and a corona discharger for static elimination, and 14 a cleaning blade or 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 performing image exposure with a semiconductor laser,
In a recording apparatus using a drum-shaped image carrier 23 like the recording apparatus shown in FIG. 2, the image exposure 24 is preferably performed by a laser beam scanner as shown in FIG.

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 rotated and scanned by a polygon mirror 43 rotated by a drive motor 42 , passes through an f-theta lens 44 , has its optical path bent by a reflecting mirror 45 , and is directed onto the surface of the image carrier 23 . It is projected to form a bright line 46. 47 is an index sensor for detecting the start of beam scanning, and 48 and 49 are cylindrical lenses for correcting the inclination angle. 50a, 50b, 5
0C is a reflecting mirror that forms 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 an image carrier 23 that is uniformly charged in advance by a charger 22.
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 heald, the image exposure can be 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
The thickness of the grain e is also regulated by the grain height regulating blade 63 during conveyance. The spike control blade 63 is made of an elastic metal plate and presses against the surface of the sleeve 61 to control the thickness of the developer being conveyed. When the developer Qeyl is consumed in the developer reservoir 66, the toner T is replenished from the toner hopper 67 by the rotation of the toner supply roller 68. 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 contacts the image carrier 23 in the development area E, so that 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 something. 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 magnet with the same or different polarity is used). Two magnetic poles may be placed close to each other.

In the above-mentioned apparatus, based on the present invention, the electrostatic latent image is charged so that LV, l is 400 to 900 ■,
and LV during reversal development, 1-IV. , 1=0~200
■. However, ■. , is a DC bias voltage applied to the sleeve 61 as a developer transport carrier facing the image carrier 23.

FIGS. 5 and 6 are flowcharts showing the process of forming an electrostatic latent image.

Figure 5 shows that an electrostatic image is formed by an electrostatic image forming method in which the exposed part of the image becomes the background part and the non-exposed part becomes an electrostatic image, and during development, toner charged to the opposite polarity is attached to the electrostatic image. This shows an example of regular development performed by This is the second
According to the copying apparatus shown in the figure, the surface of the image carrier 23 in an initial state, which has been cleaned by the cleaning device 14 and has a potential of O, is uniformly charged by the charger 22.
Image exposure 24 is performed on the charged surface so that the potential of the portion other than the electrostatic image area becomes approximately 0, and the electrostatic image obtained thereby is developed by the developing device 15, and is charged to the opposite polarity. Apply toner T.

Figure 6 shows that an electrostatic image is formed by an electrostatic image forming method in which the image exposure area is an electrostatic image with a lower potential than the background area, and development is performed using toner that is charged to the same polarity as the background area potential. It shows the process of reversal development that is carried out by the adhesion of

The image forming method of the present invention can be applied to various laser light sources such as semiconductor lasers, helium-neon, argon, helium-cadmium, and other gas lasers.

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

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.

Production of Photoconductors> First, photoconductors A to E of Examples and photoconductors a%f of Comparative Examples were produced in the following manner. That is, the manufacturing procedure for each photoreceptor is common.

First, the first layer was formed as follows.

A solution in which 100 g of carboxyl group-modified vinyl chloride-vinyl acetate copolymer resin r V M CHJ (manufactured by Union Carbide) as a binder resin was dissolved in 1200 mA of an acetone-cyclohexanone (5:1) mixed solvent was used as it was. , or by dispersing the substances (contents) shown in Table 1 below in this solution for 48 hours using a ball mill,
It was used as an undercoat coating solution or a coating solution for a light absorption layer or a light scattering layer.

Using each of these coating liquids, the surface was polished to a mirror finish.
Dip coating was applied onto an aluminum raw tube (diameter 6 (HL)) for LP-3010J (manufactured by Konica), and a subbing layer, light absorption layer, or light scattering layer of a predetermined thickness was formed as the 1N layer.However, For the photoreceptor e of the comparative example, a carrier generation layer was formed directly on the aluminum tube.For the photoreceptor f of the comparative example, the aluminum tube was made of aluminum with a surface unevenness size of 1.0 to 1.2 μm. A carrier generation layer was formed directly on the raw tube.

Next, 20 g of the carrier-generating substance represented by structural formula (1) was ground in a ball mill at 240 rpm for 18 hours, and then 20 g of polycarbonate resin "Panlite K-1300j (manufactured by Ondai Kasei Co., Ltd.) was mixed with L2-dichloroethane] 000 m
Add a solution dissolved in 1 and disperse for another 24 hours,
The obtained carrier generation layer coating liquid was dip coated on the first layer or the aluminum tube to give a film thickness of about 0.5 mm.
A carrier generation layer with a thickness of μm was formed. However, only the photoreceptor e of the comparative example had a film thickness of about 2 μm.

Furthermore, 100 g of a carrier transport substance of the following structural formula (2) and 150 g of polycarbonate resin [Niepilon Z-200J (manufactured by Mitsubishi Gas Chemical Co., Ltd.) were mixed in 1000 m of toluene.
A coating solution for a carrier transport layer obtained by dissolving the carrier transport layer in 1.5% of
It was dried for hours to form a carrier transport layer with a thickness of about 20 μm.

As described above, each of the photoreceptors A to E having the individual configurations and prescriptions shown in Table 1 was manufactured using a common manufacturing procedure.
and a~[ were produced.

(The following margins continue on the next page) <Example 1> Each of the photoreceptors A-E and a-f was mounted on a modified laser printer r L'P-3010 (manufactured by Konica), and After adjusting the grid to 600±10(V), develop bias DC-480(V)
+AC700(V) (1 kllz) was applied to perform reversal development, and the resulting image was evaluated for black spots in the white background area, moiré in the halftone dot area, and image density in the black background area.

For the evaluation of black spots, the particle size and number of black spots were measured using an image analysis device "Omnicon 3000" (manufactured by Kinsei Seisakusho Co., Ltd.), and 1 co of black spots with a diameter of 0.05N or more was determined.
Judgment was made based on the number of pieces per t. The criteria for black spot evaluation are as shown in Table-2.

Table 2 Moire is evaluated visually for the presence or absence of moire in the halftone dot area with a black ground area ratio of 30%, and ○ indicates that there is no moire.
× indicates the occurrence of moiré.

The results of image evaluation for each photoreceptor are shown in Table 3.

Table 3 From the results in the above table, it can be seen that according to the method of the present invention, good results can be obtained in terms of black spots, moiré, and image density. On the other hand, when photoreceptors a''-c having a layer containing conductive titanium oxide or a carbon blank are used instead of titanium oxide that has not been conductively treated, the potential is sufficiently Furthermore, if photoreceptor d is used, which does not contain any additives and only has a thicker undercoat layer, the black spot evaluation will be good, but the sensitivity will be very low and the image density will be low. Moiré also occurs.

On the other hand, when a photoreceptor e having a thicker CGL film or a photoreceptor f having a rougher aluminum substrate surface is used, no moiré occurs, but black spots occur significantly.

<Example 2> Photoreceptors A and D of the example and photoreceptors e and f for comparison were each mounted on a modified laser printer r LP-3010J, and were heated at 10° C. and 20% low temperature and low humidity at 30°C.
Regular development was performed at a high temperature and high humidity of 80% at 80% of the resulting image, and the resulting image was evaluated for capri in the white background area, moiré in the halftone area, and image density in the black background area.

The charging conditions are a grid voltage of -500 (V), the voltage applied to the charging wire -6 (kV), and the developing conditions are Dsd (gear between the photoreceptor and the developing sleeve) 0.
3rm, development bias DC-100 (V) +AC70
0 (V) (1 kHz).

The results of image evaluation are shown in Table 4.

Table 4 *l) Many white spots (white spots with a diameter of φo, osmm or more) were generated on the black background part.

From the above results, according to the photoconductor of the example, low temperature and low humidity,
It can be seen that in images under high temperature and high humidity conditions, the image density in the black background area can be sufficiently increased without causing fogging in the white background area, moiré in the halftone area, and white spots in the black background area.

[Brief explanation of the drawing]

Figures 1 to 6 show embodiments of the present invention. Figure 1 is a sectional view of an example of a photoreceptor used in the present invention, and Figure 2 is a schematic diagram of the configuration of an image forming apparatus. , FIG. 3 is a schematic diagram of the configuration of a laser beam scanner for image exposure, FIG. 4 is a sectional view of a main part of a developing device, and FIGS. 5 and 6 are flowcharts showing the process of image formation, respectively. FIG. 7 is a partial sectional view of a conventionally used photoreceptor. FIG. 8 is a partial cross-sectional view of a photoreceptor for explaining the cause of moiré. In addition, in the symbols shown in the drawings, 1... Conductive substrate 4... Carrier transport layer 6... Carrier generation layer 7... Light scattering layer 8... Photosensitive layer 12... ... Fixing device 13 ... Static eliminator 14 ... Cleaning device 15 ... Developing device 20 ... Pre-transfer exposure lamp 21 ... Transfer device 22 ... Charger 23 ... Image carrier 41 ... Laser 43 ... Mirror scanner 44 ... Imaging f-theta lens 48.49 ... Cylindrical lens 51 ...
Laser beam 61...Developing sleeve 62...Magnet 63...Layer thickness regulating blade 69...Bias power supply 70...Protection resistor. Agent Patent Attorney Aisaka Late stage 1 Fig. 2 Fig. 4 Fig. n Fig. 5 P2τ6i-71

Claims (1)

[Claims] 1. In an image forming method using a photoreceptor having a photosensitive layer comprising a carrier transport layer provided on a carrier generation layer, the photoreceptor is provided between the carrier generation layer and a conductive substrate and is conductively treated with a binder substance. 1. An image forming method comprising the step of charging a photoreceptor having a light scattering layer containing titanium oxide, which does not contain titanium oxide, and then forming an electrostatic latent image by irradiating the photoreceptor with laser light.