JPH0560866B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a method for dispersing a phthalocyanine derivative that can be used in an electrophotographic photoreceptor, particularly in a copier or a laser printer, into a binder made of an insulating polymer material. The present invention relates to a single-layer photoreceptor.

(Prior art) Electrophotography has already been published by Carlson in the US Patent No.
As disclosed in No. 2297691, this photographic method is a clever combination of photoconductivity and electrostatic phenomena, in which the surface of a photoconductive photoreceptor is made uniform by corona discharge etc. in a dark place. It is a type of image forming method that uses photoconductivity to convert an optical image into an electrostatic latent image after being charged, and then converts it into a visible image by attaching colored charged powder (toner) to it.

The basic electrical properties required of a photoreceptor in electrophotography include the ability to charge it to an appropriate potential in the dark, and the ability to quickly dissipate the charge when irradiated with light. .
Conventionally, inorganic materials such as amorphous silicon, amorphous selenium, cadmium sulfide, and zinc oxide have been widely used as photoconductor elements for such electrophotographic photoreceptors. Although these inorganic photoconductive materials have photoconductive properties, they also have drawbacks. For example, cadmium sulfide and amorphous selenium are harmful to the human body as pollutants.
Furthermore, amorphous silicon must be manufactured by vapor deposition, resulting in high manufacturing costs. In recent years, in order to eliminate the drawbacks of these inorganic photoconductive materials, research into organic photoreceptors has progressed, making use of their many advantages such as non-pollution, flexibility, ease of manufacture, and diversity in spectral sensitivity. Various organic photoreceptors have been devised and put into practical use.

Various types of photoconductive elements have been proposed for organic photoreceptors, and among them, phthalocyanine has come to be used in photoreceptors such as laser printers because it is sensitive to long wavelength light. However, these phthalocyanine organic photoreceptors are practically used as laminated photoreceptors in which a charge generation layer and a charge transport layer are separated. Since these laminated photoreceptors are used while being negatively charged by a corona discharger, the amount of ozone generated by a negative corona discharger reaches about 10 times that of a positive corona discharger. For this reason, when using continuously,
It is known that the indoor ozone concentration increases, causing problems under the Industrial Health Act. Furthermore, it has been pointed out that electrolyte is generated as a secondary product due to ozone generated in the photoreceptor, which tends to cause surface contamination and shortens the life of the photoreceptor.

By the way, since phthalocyanine is a P-type semiconductor, if it is used as a dispersion type photoreceptor, it can be used with positive charging. Therefore, many attempts have been made to use phthalocyanine as a dispersed photoreceptor. For example, JP-A-59
- Publication No. 105550 discloses a method for improving sensitivity by uniformly dispersing phthalocyanine pigments using a specific phenolic resin. In JP-A-57-185044, poly-N-vinylcarbazole and molecular weight 5000
-400,000 polyester resin mixture is used to improve sensitivity. Tokukai Akira
No. 59-15250 and Japanese Unexamined Patent Publication No. 59-219752 use a mixture of acrylic resin with a molecular weight of 2000-40000, melamine resin, etc. as a binder to improve printing durability during repeated use. Further, in JP-A-60-207145, moisture resistance is improved by using a mixture of polyester, polycarbonate, and acrylic resin as a binder.

Although each of these techniques can achieve desired effects, it is still not sufficient to provide a dispersed single-layer photoreceptor with overall excellent electrophotographic properties. For example, acrylic resin, which has traditionally been used as a binder component, has a molecular weight of 2000-
40,000, but a molecular weight of about 2,000 is liquid, and a molecular weight of 20,000 or more is difficult to dissolve in organic solvents, so the range that can be practically used as a binder is a molecular weight of 10,000-20,000. However, even if the molecular weight is within this range, the dark decay rate is large and poses a practical problem because the phthalocyanine particles are incompletely coated. A further problem is that due to the low charging ability, the charging potential decreases during repeated use. The inability to charge an electrophotographic photoreceptor is a fatal drawback.

The problems with practical use of phthalocyanine as a dispersion type photoreceptor with practical sensitivity are (1) the charging potential decreases due to repeated charging and exposure; (2) There is a so-called induction period in which there is a delay in the attenuation of the surface potential immediately after light irradiation, so the phenomenon appears as if the power has decreased. (3) It is difficult to produce a dispersed coating liquid because it is difficult to disperse phthalocyanine in the coating process for producing photoreceptors. (4) Sensitivity and chargeability may deteriorate under humidity or acidic gas atmospheres. Regarding (1), (2), and (4), these are fundamental problems when used as a photoconductor, and the reason for this is that the carrier generated from the phthalocyanine is stuck at the interface between the phthalocyanine and the binder. The main causes are thought to be deterioration of the surface of the photoreceptor due to ozone and NOx generated by corona discharge during repeated charging and exposure. Incidentally, in a dispersion type photoreceptor, the layer for charge retention is located in an extremely thin portion of the surface of the photoreceptor, and the state of phthalocyanine there greatly affects charging properties and sensitivity. By the way, phthalocyanine is NOX
It is known that it is used as an adsorption sensor for adsorbing acceptor substances such as NOX. Due to these properties, if the phthalocyanine content is increased, the durability will be significantly reduced due to the adsorption of ozone and NOX generated during the electrophotographic process. However, in the actual environment in which the photoreceptor is used, there are various other harmful substances, and adsorption of these substances causes a complex contamination effect and reduces durability. There are methods to prevent these adsorptions, such as providing a protective layer on the surface of the photoreceptor or adding additives such as antioxidants, but this is essential as it impairs mechanical durability and electrostatic properties. It's not a typical thing. Essentially, the phthalocyanine in the binder must be coated to provide sufficient barrier properties, or the amount of phthalocyanine used in the binder must be reduced. However, if the binder compositions known up to now are coated with phthalocyanine or the amount of phthalocyanine is reduced, the sensitivity will decrease due to the reduction of carriers and carrier traps, and the electrostatic properties will change. Side effects such as Regarding (2), a method is known in which an electron-withdrawing substance such as dichlorobenzoquinone is added when phthalocyanine and a binder are mixed, but this method suffers from defects such as increased dark decay. In addition, manufacturing problems related to (3) include insufficient smoothness on the surface of the photosensitive layer, noise in image quality due to aggregates of phthalocyanine inside the photosensitive layer, and problems related to stability of image quality. It is.

Phthalocyanine is often used as a pigment in inks and paints, and in these applications, surfactants are used to assist in dispersion. However, in electrophotographic photoreceptors, due to electrical resistance, the use of surfactants, which are low-resistance substances, cannot be used because they result in a decrease in charging performance.

(Purpose of the Invention) The present inventors have improved the dispersion stability during the production of a photoreceptor coating liquid in a dispersed single-layer photoreceptor using phthalocyanine without using additives harmful to electrophotographic properties. The object of the present invention is to further improve and improve the above-mentioned defects in electrophotographic properties.

(Structure of the Invention) The present inventors attempted to achieve the above-mentioned object, and as a result of intensive research using a vast variety of binder compositions in combination with phthalocyanine, the present inventors found that electron-withdrawing groups such as nitro groups In electrophotographic photoreceptors whose photosensitive component is metal phthalocyanine containing The inventors have discovered that it is possible to obtain a photoreceptor with excellent durability and long life by ensuring sensitivity and improving the stability of repeated charging characteristics, leading to the present invention.

The structure of the photoreceptor according to the present invention is a single-layer photoreceptor made by dispersing phthalocyanine-based conductive powder in a binder made of a mixture of polyester resin and melamine resin.

The phthalocyanine according to the present invention is a metal-free phthalocyanine, a metal phthalocyanine, or a mixture thereof. Metal phthalocyanine metals include copper, silver, beryllium, magnesium, calcium, zinc, cadmium, beryllium, magnesium, mercury, gallium, indium, lanthanum, neodymium, titanium, tin, lead, vanadium, antimony, chromium, molybdenum, uranium, These include manganese, iron, cobalt, palladium, aluminum, silver and platinum. In addition, the central core of phthalocyanine is not a metal atom, but
It may be a metal halide having a valence of 3 or more. Furthermore, it may be a low halogenated phthalocyanine. The phthalocyanine may be obtained by any manufacturing method, and not only phthalocyanine called crude but also pigmented phthalocyanine may be used. In addition, phthalocyanine is synthesized by synthesis method, purification method,
It is known that various crystal forms can be obtained depending on the pigmentation conditions. For example, in copper phthalocyanine, α type, β type, γ type, δ type, ε type,
type, and also in metal-free phthalocyanine.
type, β type, γ type, δ type, ε type, x type, τ type, etc., but the present invention is not limited to these crystal types. However, it is preferable to use phthalocyanine which has excellent photoconductivity.
−11021, Special Publication No. 46-42511, Special Publication No. 1977-163
It is a photoconductive phthalocyanine compound described in Japanese Patent Publication No. 49-17535, Japanese Patent Publication No. 50-5059, Japanese Patent Publication No. 38543-1983, etc.

That is, in the phthalocyanine photoconductive material, the hydrogen atom of the benzene nucleus in the phthalocyanine molecule is substituted with at least one electron-withdrawing group selected from the group consisting of a nitro group, a cyano group, a halogen group, a sulfone group, and a carboxyl group. An acidic substance is preferable in order to have an affinity with the phthalocyanine derivative and the metal lid. However, acidic substances that are too strongly adsorbed usually have low electrical resistance. or,
Even if this is not the case, when phthalocyanine is coated with such a substance, it is difficult to form an electrically good interface for retaining the charge even in the electric field during charging, so when used as a photoreceptor, the charge is not maintained. In addition, long-term dispersion stability is also poor in the production of photosensitive coating liquids. Therefore, it must have appropriate acidity. As for acidity,
The acidity is preferably about the same as a carboxyl group, and
It has been found that low molecular weight polyester resins having an acid value between 2 and 30 are excellent. However, considering the shape of its molecules, low-molecular polyester resins have excellent adsorption ability to the surface of phthalocyanine particles and are characterized by excellent coverage of phthalocyanine particles. When used as a bonding material, only a mechanically very weak photosensitive layer is obtained, and it cannot be used as is. Alternatively, it can be obtained by mixing at least one of a long-term dispersion-stable cyanine and a metal-free phthalocyanine with an inorganic acid capable of forming a salt with them, such as concentrated sulfuric acid, and precipitating the mixture with water or a basic substance. Preferably, a phthalocyanine photoconductive composition is used.

The binder used for the photoreceptor has high resistance, and the carrier must move quickly without being trapped in the binder, and the carrier generated from phthalocyanine must be quickly injected into the binder. It must be. For this purpose, the contact between the phthalocyanine and the binder must be sufficient and intimate. That is, the binder used must have a high affinity with the phthalocyanine, and must sufficiently cover the phthalocyanine particles. For this purpose, it has been found that the shape of the binder molecules that is close to a linear chain and has a small molecular weight is suitable because it is easy to align and adsorb onto the surface of the phthalocyanine particles. Furthermore, if we take into account that phthalocyanine retains a basic substance as a factor that makes it easier to align and adsorb onto the surface of phthalocyanine particles, the combination of a compound with basicity can improve dispersion stability. I found that it had a big effect. These basic compounds must not disturb the adsorption relationship of polyester resin molecules oriented on the surface of the phthalocyanine particles. Furthermore, many functional groups in polyester resin molecules have excellent adsorption ability on the surface of phthalocyanine particles, contributing to the coverage, dispersibility, and electrostatic properties of the particles, and these adsorption equilibriums may be impaired. must not be We have found that melamine compounds are suitable as compounds that meet these conditions.

In the present invention, by using a low-molecular-weight melamine resin in combination, many functional groups of the polyester resin molecules are adsorbed to the phthalocyanine particles and are involved in coating the phthalocyanine particles, but some of the terminals of the polyester resin molecules By heating the carboxyl group or hydroxyl group with the butylated methylol group of the melamine resin, a condensation reaction is caused, and crosslinking is effected to obtain a strong photosensitive layer. In addition, when this binder resin composition is used, it not only improves the dispersibility of phthalocyanine, but also reduces the amount of phthalocyanine used by 40% compared to conventional binder resins. It was found that it was possible to reduce the amount by about %. The hardness of the photoreceptor surface was 2H on a pencil scale. This means that the surface hardness of the multilayer organic photoreceptors currently in practical use is from B on the pencil hardness scale.
It is recognized that it is much harder than HB. This increases the resistance to mechanical frictional forces that the photoreceptor receives during development, cleaning, and transfer. Furthermore, as a result of the well-dispersed state, the surface smoothness of the photoreceptor improves, resulting in improved image quality.The fact that the phthalocyanine particles are sufficiently coated with the resin even under various environments results in a more significant improvement in environmental resistance. Admitted.

Raw materials for the polyester resin used as the binder resin in the present invention include aromatic saturated acids such as phthalic anhydride and terephthalic acid, aliphatic saturated acids such as hexadrophthalic anhydride, succinic acid, and azelaic acid, and maleic anhydride. At least one type of unsaturated acid such as an acid is used as a polybasic acid component, and at least one type of diols such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol are used as a polyhydric alcohol component to undergo a condensation reaction, and the molecular weight is 500−5000, acid value is 2−
30 is appropriate.

Although a condensate of melamine and formalin can be used as the low-molecular melamine resin, an ether compound made of butyl alcohol is preferred from the viewpoint of compatibility with the polyester resin. It is not preferable that the molecular weight of the polyester resin exceeds an appropriate range because it impairs its compatibility with the melamine resin.

Regarding the blending ratio of polyester resin and melamine resin, the solid content ratio is 10-50 parts by weight of melamine resin per 100 parts by weight of polyester resin. As the amount of melamine resin increases, the hardness of the coating increases, but the curing speed decreases. As the amount of phthalocyanine increases, the sensitivity improves, but the dark decay increases, making it difficult to retain charge and impractical, so the solid content of the binder increases. The amount of phthalocyanine relative to 100 parts by weight is selected in the range of 12 to 50 parts by weight, but from the viewpoint of environmental friendliness, dispersibility, and mechanical strength, 12 to 30 parts by weight is preferable.

The present invention involves uniformly dispersing the above-mentioned phthalocyanine photoconductive powder, polyester resin, and melamine resin in a solution in a solvent such as cyclohexanone, ethyl acetate, or cellosolve at a predetermined ratio, and applying the resulting coating liquid to a conductive substrate. It is completed by applying it on top and letting it dry. The thickness of the photosensitive layer is preferably 5-30 microns. Drying conditions are 100℃
Preferably, the heating time is 10 minutes to 30 minutes under heating at -180°C. If the drying is insufficient, the dark resistance decreases and the chargeability is impaired, and if the drying is performed at excessively high temperatures, the chargeability decreases.

In order to use the composition according to the present invention as an electrophotographic photoreceptor, the composition is uniformly dispersed together with a binder resin, a solvent, etc. using a kneading/dispersing machine such as a ball mill or attritor, and then coated on a conductive support. to form a photosensitive layer. As for the coating method, if necessary, add a solvent to the photoconductive composition to adjust the viscosity, and use an air doctor coater, blade coater, rod coater, reverse roll coater, spray coater, hot coater, squeeze coater, dip coater, etc. Forms a film. After coating, the photoconductive layer is dried using a suitable drying device until it accepts a sufficient electrical charge.

The support used in the electrophotographic photoreceptor of the present invention may be any support as long as it is endowed with conductivity, and any type of conductive layer conventionally used may be used. Specifically, metals such as aluminum, copper, stainless steel, and brass;
Examples include plastics on which alumite, indium oxide, tin oxide, etc. are vapor-deposited or laminated, and conductive particles such as carbon black, tin particles, and aluminum particles dispersed therein. Moreover, the shape may be on a sheet or other shapes.
In addition, when using the electrophotographic photoreceptor according to the present invention, the light source may be a normal halogen lamp, etc., or a light source with low sensitivity.
Since the wavelength is 750 nm or more, laser light such as a gallium-aluminum-arsenic semiconductor laser (oscillation wavelength 780 nm) can also be used.

A detailed explanation will be given below using examples.

Example 1 222 parts of phthalic anhydride (parts by weight are omitted below), 49 parts of maleic anhydride, and 233 parts of diethylene glycol were heated and reacted in a nitrogen gas atmosphere, and the reaction was continued until the acid value reached 15. The obtained polyester resin was a pale yellow brittle solid resin with a molecular weight of about 3,000.

Separately, thoroughly stir 40 parts of copper phthalocyanine and 0.5 part of tetranitrocopper phthalocyanine in 500 parts of 98% concentrated sulfuric acid.
Dissolve while stirring. Pour the dissolved solution into 5000 parts of water to precipitate a composition of copper phthalocyanine and tetranitrocopper phthalocyanine, and then filter and wash with water.
A photoconductive powder was obtained by drying at 120°C under reduced pressure.

12.6 parts of polyester resin, melamine resin (Supervecamine-109-65 manufactured by Dainippon Ink Chemical Co., Ltd.)
A composition consisting of 5.0 parts of copper phthalocyanine, 4 parts of copper phthalocyanine prepared above, and 75 parts of cyclohexanone was kneaded in a magnetic ball mill for 24 hours to obtain a photoconductive coating liquid. Next, it was coated on an 80-micron thick aluminum foil to a dry film thickness of 15 microns, and heated at 130°C for 30 minutes.
It was dried by heating for a minute to obtain an electrophotographic photoreceptor.

The maximum surface potential of this photoreceptor is +1200 volts, and since it is practically used at about +600 volts, the charging capacity has sufficient margin. The dark decay rate is 7% after 5 seconds, and the half-value sensitivity is 3 lux. seconds, the residual potential is
It was 20 volts. repeated charging and exposure,
There was almost no change in the charging potential after 10,000 cycles.
In addition, almost no change in sensitivity was observed.

Example 2 222 parts of phthalic anhydride (parts by weight are omitted below), 49 parts of maleic anhydride, and 269.5 parts of diethylene glycol were heated and reacted in a nitrogen gas atmosphere,
The reaction was continued until the acid value reached 7. The obtained polyester resin was a pale yellow brittle solid resin with a molecular weight of about 3,200.

Next, copper phthalocyanine 4 obtained in Example 1
12.6 parts of polyester resin, melamine resin (Supervecamine-109-65 manufactured by Dainippon Ink Chemical Co., Ltd.)
A composition consisting of 5.0 parts of copper phthalocyanine, 4 parts of copper phthalocyanine prepared above, and 75 parts of cyclohexanone was kneaded in a magnetic ball mill for 24 hours to obtain a photoconductive coating liquid. Next, it was coated on an 80-micron thick aluminum foil to a dry film thickness of 15 microns, and heated at 130°C for 30 minutes.
It was dried by heating for a minute to obtain an electrophotographic photoreceptor.

The maximum surface potential of this photoreceptor is +1150 volts, and it is practically used at about +600 volts, so the charging capacity has sufficient margin. Dark decay rate after 5 seconds
6.5%, half-value sensitivity is 3.1 lux. seconds, the residual potential was 22 volts. repeated charging and exposure,
There was almost no change in the charging potential after 10,000 cycles.
In addition, almost no change in sensitivity was observed.

Example 3 222 parts of phthalic anhydride (parts by weight are omitted below), 98 parts of maleic anhydride, and 233 parts of diethylene glycol were heated and reacted in a nitrogen gas atmosphere, and the reaction was continued until the acid value reached 25. The obtained polyester resin was a pale yellow brittle solid resin with a molecular weight of about 2,500.

Next, copper phthalocyanine 4 obtained in Example 1
12.6 parts of polyester resin, melamine resin (Supervecamine-109-65 manufactured by Dainippon Ink Chemical Co., Ltd.)
A composition consisting of 5.0 parts of copper phthalocyanine, 4 parts of copper phthalocyanine prepared above, and 75 parts of cyclohexanone was kneaded in a magnetic ball mill for 24 hours to obtain a photoconductive coating liquid. Next, it was coated on an 80-micron thick aluminum foil to a dry film thickness of 15 microns, and heated at 130°C for 30 minutes.
It was dried by heating for a minute to obtain an electrophotographic photoreceptor.

The maximum surface potential of this photoreceptor is +1100 volts, and since it is practically used at about +600 volts, the charging capacity has sufficient margin. The dark decay rate is 8% after 5 seconds, and the half-value sensitivity is 2.9 Lux. seconds, the residual potential was 18 volts. repeated charging and exposure,
There was almost no change in the charging potential after 10,000 cycles.
Moreover, almost no change in sensitivity was observed.

Example 4 4 parts of the copper phthalocyanine obtained in Example 1, 21 parts of a commercially available polyester resin (Almatex 645 manufactured by Mitsui Toatsu Co., Ltd.) having an acid value of 3-7 and a molecular weight of about 4000,
Melamine resin (Yuban 20HS manufactured by Mitsui Toatsu Co., Ltd.) 4.6
A photoconductive coating liquid was obtained by kneading a composition consisting of 1.5 parts and 65 parts of cyclohexanone in a magnetic ball mill for 24 hours. Next, it was coated onto an 80-micron thick aluminum foil to a dry film thickness of 15 microns, and heated to 150°C.
The electrophotographic photoreceptor was dried by heating for 20 minutes. The surface hardness of the photoreceptor was 2H on a pencil hardness scale. It also had excellent wear resistance. The maximum surface potential of this photoreceptor is +K100 volts, and since it is practically used at about +600 volts, the charging capacity has sufficient margin. The dark decay rate is 9% after 5 seconds, and the half-value sensitivity is 3.5 Lux. seconds, the residual potential was 20 volts. After 10,000 repetitions of charging and exposure, the charging potential hardly changed. Moreover, almost no change in sensitivity was observed.

Comparative Example 1 4 parts of phthalocyanine obtained in Example 1, acrylic resin (Alumatex 762LV55A Mitsui Toatsu Co., Ltd.)
A photoconductive coating liquid was obtained by kneading a composition consisting of 20.6 parts of melamine resin (Yuban 20HS manufactured by Mitsui Toatsu Co., Ltd.), 5.8 parts of melamine resin (manufactured by Mitsui Toatsu Co., Ltd.), and 60 parts of cyclohexanone for 24 hours in a magnetic ball mill. Next, it was coated onto an 80 micron aluminum foil to a dry film thickness of 15 microns, and dried by heating at 150° C. for 30 minutes to obtain an electrophotographic photoreceptor. The maximum charging potential of this photoreceptor is +800 volts, the dark decay rate is 20% after 5 seconds, and the half-value sensitivity is 4 lux. It was hot in seconds. After 500 repetitions of charging exposure, the charging potential decreased to 50% of the initial value.

Comparative Example 2 222 parts of phthalic anhydride (parts by weight are shown, omitted below), 49 parts of maleic anhydride, and 462 parts of diethylene glycol were heated and reacted in a nitrogen gas atmosphere, and the reaction was continued until the acid value reached 1.5. The obtained polyester resin was a pale yellow brittle solid resin with a molecular weight of about 1800.

Next, copper phthalocyanine 4 obtained in Example 1
12.6 parts of polyester resin, melamine resin (Supervecamine-109-65 manufactured by Dainippon Ink Chemical Co., Ltd.)
A composition consisting of 5.0 parts of copper phthalocyanine, 4 parts of copper phthalocyanine prepared above, and 75 parts of cyclohexanone was kneaded in a magnetic ball mill for 24 hours to obtain a photoconductive coating liquid. Next, it was coated on an 80-micron thick aluminum foil to a dry film thickness of 15 microns, and heated at 130°C for 30 minutes.
It was dried by heating for a minute to obtain an electrophotographic photoreceptor.

The maximum surface potential of this photoreceptor is +1000 volts, and it is practically used at about +600 volts, so the charging ability has sufficient margin. The dark decay rate is 9% after 5 seconds, and the half-value sensitivity is 2.8 Lux. seconds, the residual potential was 18 volts. However, after repeated charging and exposure, the initial charging potential was about half that after about 2000 times, which was insufficient for practical use.

Comparative Example 3 222 parts of phthalic anhydride (parts by weight are omitted below), 196 parts of maleic anhydride, and 233 parts of diethylene glycol were heated and reacted in a nitrogen gas atmosphere, and the reaction was continued until the acid value reached 35. The obtained polyester resin was a pale yellow brittle solid resin with a molecular weight of about 4,000.

Next, copper phthalocyanine 4 obtained in Example 1
12.6 parts of polyester resin, melamine resin (Supervecamine-109-65 manufactured by Dainippon Ink Chemical Co., Ltd.)
A composition consisting of 5.0 parts of copper phthalocyanine, 4 parts of copper phthalocyanine prepared above, and 75 parts of cyclohexanone was kneaded in a magnetic ball mill for 24 hours to obtain a photoconductive coating liquid. The dry film thickness was then deposited on an 80 chrome aluminum foil.
It was coated to a thickness of 15 microns and dried by heating at 130°C for 30 minutes to obtain an electrophotographic photoreceptor.

The maximum surface potential of this photoreceptor was +490 volts, which was insufficient for practical use.

(Effects of the Invention) In the present invention, since the phthalocyanine photoconductive powder has an electron-withdrawing group in the molecule, the so-called induction phenomenon due to the delay in light attenuation described above does not easily occur, and the polyester used as the binder Sensitivity is guaranteed through the mutually complementary dispersion effects of the resin and melamine resin, so photoreceptors manufactured using the previously developed phthalocyanine and binder have excellent sensitivity and require repeated operations many times during charging and exposure. There is almost no change in the charging potential even after use, and the high surface hardness provides high mechanical strength and excellent wear resistance.Also, since the phthalocyanine particles are sufficiently coated with the binder, it has excellent resistance to wear. An electrophotographic photoreceptor was obtained which has excellent environmental properties and surface smoothness, and which has greatly improved the drawbacks of conventional single-layer photoreceptors.

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor provided with a dispersed photosensitive layer, a polyester having a molecular weight of 500 to 5000 and an acid value of 2 to 30 as a binder for dispersing phthalocyanine-based photoconductive powder. A phthalocyanine electrophotographic photoreceptor characterized in that it uses a mixture of a resin and a melamine resin that is heat-crosslinked. 2. A phthalocyanine derivative in which the phthalocyanine-based photoconductive powder has a phthalocyanine and a benzene nucleus of the phthalocyanine molecule substituted with at least one electron-withdrawing group selected from a nitro group, a cyano group, a halogen group, a sulfone group, and a carboxyl group. The electrophotographic photoreceptor according to claim 1, which is selected from the following.