JPH07128896A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic photoreceptor improved in wear resistance without deteriorating electrophotographic characteristics such as chargeability, photosensitivity, dark decay, digital property or the like by providing a protective layer using an acrylic ultraviolet curing resin on the surface of photosensitive layer. CONSTITUTION:The electrophotographic photoreceptor is provided with the protective layer using the acrylic ultraviolet curing resin on the surface of the photosensitive layer made by dispersing a phthalocyanine based photoconductive compound in a binding resin. And the photoreceptor is provided with a protective layer using a mixture of a polyester resin with butylated melamine resin the surface of the photosensitive layer made by dispersing the phthalocyanine based photoconductive compound in the binding resin. The protective layer using the acrylic ultraviolet curing resin and the protective layer using the mixture of the polyester resin with the butylated melamine resin repeatingly are capable of obtaining excellent image and has excellent wear resistance even when the processes of positive charge, image exposure, development, transfer and cleaning are repeated over 30000 cycles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoconductor used in electrophotographic copying machines and printers.

[0002]

2. Description of the Related Art In electrophotographic recording used in copying machines, printers, etc., the surface of a photoconductor is charged and then exposed to form an electrostatic latent image, which is visualized by a developer (development). Then, the visible image is transferred onto paper or the like and fixed to obtain an image. After that, the photoconductor is initialized by removing the adhered toner and removing the charge, and is repeatedly used many times.

Therefore, in addition to electrophotographic characteristics such as good charging characteristics and photosensitivity and small dark decay, the electrophotographic photosensitive member has a small change with time in the above electrophotographic characteristics upon repeated use. It is required to have excellent physical properties such as printing property, abrasion resistance, and moisture resistance, and chemical resistance to ozone and the like generated during charging.

Conventionally, inorganic materials such as selenium, cadmium sulfide, and zinc sulfide have been used as electrophotographic photoreceptors, but the problems of material toxicity and digital copying machines,
Organic photoconductors have come to be widely used in order to cope with longer wavelengths of semiconductor lasers and LED light used in printers and the like. The photoconductor can be classified into a positive charging type and a negative charging type, but the positive charging type, which can reduce the amount of ozone generated during corona charging, is superior to the health protection of the user of the device. A positive type organic photoconductor is receiving much attention among organic photoconductors.

As the constitution of the positive charging type organic photoreceptor, an undercoat layer, a photosensitive layer (photoconductive layer), a protective layer, or a photosensitive layer, a protective layer, an undercoat layer, a charge transport layer, on a conductive support, A layer in which a photosensitive layer, a protective layer, or a charge transport layer, a photosensitive layer, and a protective layer are sequentially laminated is well known.

As the protective layer of the electrophotographic photoreceptor, for example, polyester resin, polycarbonate resin, polystyrene resin, polyurethane resin, epoxy resin, acrylic resin, as shown in JP-A-55-157748,
Examples thereof include those based on polyvinyl chloride resins, vinyl chloride-vinyl acetate copolymer resins, silicone resins and the like.

[0007]

However, even if the above-mentioned protective film is used, the organic photoconductor has weaker abrasion resistance than the inorganic photoconductor, and therefore, the recording paper, the transfer drum, the transfer drum, etc. Contact with the belt (when an intermediate transfer medium is used) sometimes causes defects such as scratches and peeling in the photosensitive layer.

The present invention has been made to solve the above problems, and has improved abrasion resistance without deteriorating the electrophotographic characteristics such as charging property, photosensitivity, dark decay and digital property. An object is to provide an electrophotographic photoreceptor.

[0009]

According to a first aspect of the present invention, there is provided an electrophotographic photosensitive member, in which a surface of a photosensitive layer having a phthalocyanine photoconductive compound dispersed in a binder resin is protected by an acrylic ultraviolet curing resin. It is provided with layers.

Further, in the electrophotographic photoreceptor according to claim 2 of the present invention, the surface of the photosensitive layer in which the phthalocyanine photoconductive compound is dispersed in the binder resin is protected by a mixture of a polyester resin and a butylated melamine resin. It is provided with layers.

Further, in the electrophotographic photoreceptor according to claim 3 of the present invention, the mixture amount of the polyester resin and the butylated melamine resin is 60 to 90% by weight of the polyester resin and 10 to 40% by weight of the butylated melamine resin. % Is what.

Further, in the electrophotographic photoreceptor according to claim 4 of the present invention, the thickness of each protective layer is 0.1 to 2.0 μm.

Further, in the electrophotographic photoreceptor according to claim 5 of the present invention, the surface of the photosensitive layer having a phthalocyanine photoconductive compound dispersed in a binder resin is subjected to polishing treatment with a solvent,
A protective layer is provided on the polished surface.

Further, in the electrophotographic photoreceptor according to claim 6 of the present invention, the phthalocyanine photoconductive compound is an X-type crystal of a metal-free phthalocyanine having an average particle diameter of 0.5 μm or less, and the phthalocyanine photoconductive compound is contained in the binder resin in an amount of 15 times. -40% by weight, and the thickness of the photosensitive layer is 10-30 μm.

[0015]

The protective layer made of the acrylic UV-curable resin and the protective layer made of the mixture of the polyester resin and the butylated melamine resin according to claims 1 and 2 of the present invention are positively charged,
When the steps of image exposure, development, transfer, and cleaning were repeated, a good image could be repeatedly obtained over 30,000 cycles, and the abrasion resistance was good. It was also confirmed that the electrical characteristics were comparable to those of the conventional photoconductor.

The blending amount of the above-mentioned polyester resin and butylated melamine resin is such that the polyester resin 60
~ 90 wt%, butylated melamine resin 10-40 wt%
Sufficient cure is obtained when

The thickness of each protective layer is 0.1-2.
It is necessary that the thickness be in the range of 0 μm, and if it is thinner than this range, the mechanical properties, such as printing durability, will be significantly reduced. On the other hand, when the thickness is larger than this range, the photoresponse speed becomes insufficient and the basic performance of the photoconductor is deteriorated.

The surface of the photosensitive layer in which a phthalocyanine photoconductive compound is dispersed in a binder resin is subjected to a polishing treatment with a solvent to smooth the surface, and a protective layer is provided on the polished surface. It reduces frictional resistance and improves wear resistance.

Further, the charge generating material not only has a large light absorption property, excellent heat resistance, chemical resistance and light resistance, but also has a large photoconductivity by light irradiation, that is, an electron / hole. A phthalocyanine-based photoconductive compound that is excellent in pair generation efficiency is preferably used, but among the phthalocyanine-based photoconductive compounds, an X-type crystal of a metal-free phthalocyanine that does not easily generate a coordination defect may be used. Further, the smaller the particle size of the phthalocyanine-based photoconductive compound, the better the dispersion. Further, in order for the photoconductor to function as a positive charging type photoconductor, the blending ratio of the phthalocyanine photoconductive compound needs to be 15 to 40%. Further, the film thickness of the photosensitive layer needs to be in the range of 10 to 30 μm in consideration of charge retention ability, photoresponse speed and the like.

[0020]

【Example】

Example 1. As the conductive support of the electrophotographic photoreceptor used in each of the examples of the present invention, a conductor or an insulator subjected to a conductive treatment is used. Examples of such a material include Al, Ni, Fe, Cu, Au and other metals or alloys, polyester, polycarbonate, polyimide, glass and other insulating substrates on which Al, Ag, A are formed.
Examples include a thin film of a metal such as u or a conductive material such as In ₂ O ₂ and SnO ₂ , and a paper that has been subjected to a conductive treatment. The shape of the conductive support is not particularly limited, and a drum shape, a plate shape, or a belt shape may be used if necessary.

The photoconductive layer may be provided directly on the conductive support, but in order to improve the adhesion between layers and to add a function of blocking charges, the photoconductive layer is provided before the photoconductive layer is provided. It is common to stack conductive layers.

In the positive charging type photoreceptor, a phthalocyanine photoconductive compound is usually used as a photoconductive layer in a state of being dispersed in a resin binder. As the resin binder, a good charge retention rate is obtained. A good dispersion medium of phthalocyanine is used, and from the viewpoint of ozone resistance, it is preferable that the phthalocyanine has a small amount of ionic and radical active species and does not dissolve or swell during the treatment with the reactive monomer or oligomer. For example, acrylic resins, polyester resins, urethane resins, butyral resins, and thermosetting resins obtained by thermosetting them with amino resins, isocyanate resins and the like are preferably used.

As the phthalocyanine-based photoconductive compound used for the photoconductive layer, it is preferable to use an X-type crystal of metal-free phthalocyanine. In the metal phthalocyanine, phthalocyanine is ideally coordinated with the metal to maintain electrical neutrality, but in reality, a defective portion is likely to occur and that portion is easily oxidized by ozone. On the other hand, the metal-free phthalocyanine has only a small hydrogen atom coordinated thereto and is less likely to generate a coordination defect and has ozone resistance. Further, the smaller the particle size of the phthalocyanine-based photoconductive compound, the better the dispersion. Further, the compounding ratio of the phthalocyanine photoconductive compound in the photoreceptor is 15 to 4
It needs to be 0%. This is a condition necessary for the photoconductor to function as a positive charging type photoconductor, and when it is less than this range, the photosensitivity is remarkably reduced, and when it is more than this range, it is a bulk of the photoconductor. The resistance is lowered and the charge retention ability is lowered. The most preferable range is 25 to 35% in terms of the balance between photosensitivity and charge retention ability. Further, the thickness of the photosensitive layer needs to be in the range of 10 to 30 μm. If it is thinner than this, the charge retention ability is lowered, pinholes are easily generated, and mechanical properties such as printing durability are deteriorated. It will drop significantly. On the other hand, if the thickness is thicker than this range, the photoresponse speed will be insufficient, and the amount of expensive photoconductive material used will increase, which is uneconomical. Considering the charge retention ability, the photoresponse speed, etc., the most preferable range of the film thickness is 15 to 25 μm.

Depending on the structure, a charge transport material may be added to the photoconductive layer for the purpose of improving photosensitivity. Examples of the charge transport material include heterocyclic compounds, hydrazone compounds, The compound is selected from compounds such as arylamine compounds in consideration of compatibility with the charge generation material.

The protective layer provided on the photoconductive layer is formed by diluting a resin with an appropriate solvent, applying the resin on the surface of the photosensitive layer by a dipping method, a spray method or the like and curing the resin.

Next, the first embodiment will be described more specifically. A polyamide resin layer was formed as an undercoat layer on a polished aluminum drum. Next, 567 g of X-type metal-free phthalocyanine and polyester resin 1055
g, butylated melamine resin 264g, toluene 3000
and a mixture of MEK of 9000 g were dispersed by a basket mill to prepare a dispersion liquid. This dispersion is applied on the above-mentioned polyamide layer by a dipping method,
The photosensitive layer was formed by thermosetting for 4 hours. Next, polyester resin (Mitsui Toatsu Co., Ltd., Almatex P645) 70
A protective layer having an average film thickness of 1.0 μm is formed by immersing (coating) a solution containing 30% by weight of butylated melamine resin (Mitsui Toatsu Co., Ltd., Uban 20HS) in an amount of 30% by weight diluted with toluene and heat curing. Then, a photoconductor was prototyped. Using a prototype printer, the steps of positive charging, image exposure, development, transfer, and cleaning were repeated for this photosensitive member.
It was confirmed that good images could be repeatedly obtained over 0 cycles and that the abrasion resistance was good. In addition, when the electrical characteristics such as photosensitivity, dark decay, and charge retention were tested at the initial stage and after 30,000 cycles, it was confirmed that the characteristics were comparable to those of the photoconductors used conventionally. It was The above results are shown in Table 1. In Table 1, double circles indicate good, o indicates good, and x indicates bad.

When the above-mentioned polyester resin and butylated melamine resin are blended in amounts of 60 to 90% by weight of polyester resin and 10 to 40% by weight of butylated melamine resin, sufficient curing can be obtained.

Example 2. In Example 1, the protective layer had a thickness of 1.0 μm, but in the present example, a similar protective layer was provided, and a photoreceptor having an average film thickness of 1.5 μm was prototyped. When the same test as in Example 1 was conducted, the repetition was further extended, a good image was obtained even after 30,000 cycles, and the abrasion resistance was further better than that in Example 1. It was also confirmed that the electrical characteristics were comparable to those of the conventional photoconductor, as in Example 1 (Table 1). The thickness of the protective layer is required to be in the range of 0.1 to 2.0 μm, and if it is thinner than this, mechanical properties, such as printing durability, will be significantly reduced. On the other hand, when the thickness is larger than this range, the photoresponse speed becomes insufficient and the basic performance of the photoconductor is deteriorated.

Example 3. The protective layer in Examples 1 and 2 was a mixture of polyester resin and butylated melamine resin, but in this Example, an epoxy resin is used. That is, a polyamide resin layer was formed as an undercoat layer on a ground aluminum drum, and then 567 g of X-type metal-free phthalocyanine, 1055 g of polyester resin, 264 g of butylated melamine resin, 3000 g of toluene, and ME.
A mixture consisting of K9000 g was dispersed by a basket mill to prepare a dispersion liquid. This dispersion is applied on the above-mentioned polyamide layer by a dipping method, and the temperature is 150 ° C. for 4 hours.
It was thermoset to form a photosensitive layer. Then, the epicoat # 815 made by Yuka Shell and Epomate B002 were mixed in a ratio of 2: 1 to immerse (apply) in a solution diluted with toluene and heat-cured to form a protective layer having an average film thickness of 1.0 μm. Then, a photoconductor was produced as a prototype. When this photoreceptor was tested in the same manner as in Example 1, it was confirmed that good images could be repeatedly obtained even after 30,000 cycles and that the electrical characteristics were also good (Table 1).

Example 4. In this embodiment, a urethane layer is used as the protective layer. That is, a layer of polyamide resin was formed as an undercoat layer on a polished aluminum drum, and then 567 g of X-type metal-free phthalocyanine, 1055 g of polyester resin, 264 g of butylated melamine resin,
A mixture of 3000 g of toluene and 9000 g of MEK was dispersed by a basket mill to prepare a dispersion liquid. This dispersion was applied on the above-mentioned polyamide layer by a dipping method and heat-cured at 150 ° C. for 4 hours to form a photosensitive layer. And urethane resin (Dainippon paint, V top)
Was dipped (applied) in a solution diluted with xylene and heat-cured to form a protective layer having an average film thickness of 1.0 μm, and a photoconductor was experimentally produced. When this photoreceptor was tested in the same manner as in Example 1, it was confirmed that good images could be repeatedly obtained even after 30,000 cycles and that the electrical characteristics were also good (Table 1).

Example 5. In this embodiment, an acrylic ultraviolet curing resin is used as the protective layer. That is, a polyamide resin layer was formed as an undercoat layer on a polished aluminum drum. Next, X-type metal-free phthalocyanine 56
7 g, polyester resin 1055 g, butylated melamine resin 264 g, toluene 3000 g, MEK 9000 g
The mixture consisting of was dispersed by a basket mill to prepare a dispersion liquid. This dispersion was applied on the above-mentioned polyamide layer by a dipping method and heat-cured at 150 ° C. for 4 hours to form a photosensitive layer. And ultraviolet curing type (UV curing type)
Acrylic resin (Dainippon Ink, Unidec C1-8
40) is dipped (applied) in a solution diluted with xylene,
UV-cured to form a protective layer with an average film thickness of 1.0 μm,
A photoconductor was prototyped. When this photoreceptor was tested in the same manner as in Example 1, it was confirmed that good images could be repeatedly obtained even after 30,000 cycles and that the electrical characteristics were also good (Table 1).

Example 6. In this example, another acrylic ultraviolet curable resin (made by Dainippon Ink and Unidec 17-824-9) is used as the protective layer. Others are the same as in the fifth embodiment. When this photoreceptor was tested in the same manner as in Example 1, it was confirmed that good images could be repeatedly obtained even after 30,000 cycles and that the electrical characteristics were also good (Table 1).

Example 7. In this embodiment, another acrylic ultraviolet curable resin (urethane acrylic resin (Dainippon Ink and Grandic 601)) is used as the protective layer. Others are the same as in the fifth embodiment. When this photoreceptor was tested in the same manner as in Example 1, it was confirmed that good images could be repeatedly obtained even after 30,000 cycles and that the electrical characteristics were also good (Table 1).

Example 8. In this example, before the protective layer was formed on the photosensitive layer, the surface of the photosensitive layer was polished with a solvent, and the protective layer was provided on the polished surface. That is, a layer of polyamide resin was formed as an undercoat layer on a polished aluminum drum, and then 567 g of X-type metal-free phthalocyanine, polyester resin 1055 g, and butylated melamine resin 26 were formed.
A mixture consisting of 4 g, toluene 3000 g and MEK 9000 g was dispersed by a basket mill to prepare a dispersion liquid. This dispersion was applied on the above-mentioned polyamide layer by a dipping method and heat-cured at 150 ° C. for 4 hours to form a photosensitive layer. Then, after polishing the photosensitive layer with a cloth containing a toluene solvent, a polyester resin (Mitsui Toatsu, Almatex P645) and a butylated melamine resin (Mitsui Toatsu, Uban 20HS) were diluted with toluene. It was dipped (applied) in a solution and thermally cured to form a protective layer having an average film thickness of 1.0 μm, and a photoconductor was experimentally produced. For this photoreceptor,
Repeated tests were conducted using a prototype printer, and good images were obtained even after 30,000 cycles, and the abrasion resistance was further improved (Table 1).

In this example, the protective layer is the same as in Example 1.
Although the same as that used in Example 1 was used, the abrasion resistance is improved even with the conventional protective layer.

As Comparative Example 1, a photoconductor in which the protective layer was changed to a conventionally used silicone resin, and as Comparative Example 2 was made a trial photoconductor in which the protective layer was changed to a conventionally used polycarbonate resin. Then, the test was conducted in the same manner as in each of the above examples. Table 1 also shows the results of Comparative Examples 1 and 2. The electrical characteristics of Comparative Example 1 at the initial stage were almost the same as those of the Examples. However, it was confirmed that the repeated image had a background fog before 2000 cycles and a good image could not be obtained, and the repeated cycle had only half of that of the example, and a good result was not obtained. In Comparative Example 2, the electrical characteristics were similar at the initial stage. Further, after 30,000 cycles, the dark decay increased and the characteristics deteriorated. In addition, the repeated image was a good image with slight thinning up to 20000 cycles, but ground fog occurred before reaching 30,000 cycles, and a good image could not be obtained.

[0037]

[Table 1]

[0038]

INDUSTRIAL APPLICABILITY As described above, in a photoreceptor comprising a photosensitive layer in which a phthalocyanine photoconductive compound is dispersed in a binder resin, a protective layer made of an acrylic ultraviolet curing resin or a polyester resin and butyl is formed on the photosensitive layer. By forming the protective layer of the mixture of the modified melamine resin, it is possible to obtain an electrophotographic photoreceptor having excellent abrasion resistance in repeated use.

In the case where the protective layer is formed of a mixture of a polyester resin and a butylated melamine resin, a blending amount of 60 to 90% by weight of the polyester resin and 10 to 40% by weight of the butylated melamine resin is sufficient. Hardness is obtained.

Further, the film thickness of each of the above-mentioned protective layers is 0.1 to 2.
When the thickness is 0 μm, excellent printing durability and photoresponsiveness can be obtained.

Further, in a photoreceptor comprising a photosensitive layer in which a phthalocyanine-based photoconductive compound is dispersed in a binder resin, the surface of the photosensitive layer is subjected to polishing treatment with a solvent, and a protective layer is formed on the polished surface, thereby repeating the process. An electrophotographic photoreceptor having excellent wear resistance in use can be obtained.

Further, the phthalocyanine-based photoconductive compound used in the photosensitive layer is an X-type crystal of metal-free phthalocyanine having an average particle size of 0.5 μm or less, and 1 in the binder resin.
5 to 40% by weight is dispersed, and the thickness of the photosensitive layer is 10 to 30 μm.
The ozone resistance, photosensitivity, charge retention ability,
Excellent printing durability and light response speed can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Enmanji Koei 8-1-1 Tsukaguchi Honmachi, Amagasaki City Mitsubishi Electric Corporation Material Device Research Center (72) Inventor Wei Nagae 8-1-1 Tsukaguchi Honmachi, Amagasaki No. Mitsubishi Electric Corporation Material Devices Research Laboratory (72) Inventor Kasuko Wakita 8-1-1 Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corporation Materials Device Research Center

Claims (6)

[Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer in which a phthalocyanine photoconductive compound is dispersed in a binder resin, wherein a protective layer made of an acrylic ultraviolet curable resin is provided on the surface of the photosensitive layer. A photoconductor for electrophotography. 2. A photoreceptor for electrophotography comprising a photosensitive layer in which a phthalocyanine photoconductive compound is dispersed in a binder resin, wherein a protective layer made of a mixture of a polyester resin and a butylated melamine resin is provided on the surface of the photosensitive layer. An electrophotographic photoreceptor characterized by the following. 3. The mixture of the polyester resin and the butylated melamine resin according to claim 2, wherein the blending amount is 60 to 90% by weight of the polyester resin and 10 to butylated melamine resin.
An electrophotographic photosensitive member characterized by being 40% by weight. 4. The electrophotographic photosensitive member according to claim 1, wherein the protective layer has a thickness of 0.1 to 2.
An electrophotographic photosensitive member characterized by having a thickness of 0 μm. 5. An electrophotographic photoreceptor comprising a photosensitive layer in which a phthalocyanine photoconductive compound is dispersed in a binder resin, wherein the surface of the photosensitive layer is polished with a solvent,
An electrophotographic photosensitive member comprising a protective layer provided on a polished surface. 6. The phthalocyanine-based photoconductive compound according to claim 1, which is an X-type crystal of a metal-free phthalocyanine having an average particle size of 0.5 μm or less, and is contained in a binder resin in an amount of 15 to 40% by weight. Dispersed, photosensitive layer thickness is 1
An electrophotographic photoconductor characterized by having a thickness of 0 to 30 μm.