JP2679366B2 - Electrophotographic photoreceptor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, particularly an electrophotographic photoreceptor having an antireflection layer.

[Conventional technology]

Usually, an electrophotographic photosensitive member is formed by providing a photosensitive layer on a conductive substrate. As the photosensitive layer, a material having photoconductivity is generally used, and examples thereof include inorganic photoconductive materials such as Se, CdS, and ZnO and organic photoconductive materials, and recently, amorphous silicon is a photoconductive material. Has been attracting attention (for example, JP-A-54-86341). Amorphous silicon electrophotographic photoreceptors are mainly formed by the glow discharge method. This amorphous silicon-based electrophotographic photoreceptor has the advantages of high sensitivity, has an extremely hard surface, excellent printing durability, and is resistant to alteration, and thus has the advantage of a long life as a photoreceptor. .

[Problems to be solved by the invention]

By the way, an electrophotographic printer of a line scanning type with a laser beam uses a helium-type laser beam.
Gas lasers having relatively short wavelengths such as cadmium laser, argon laser, and helium-neon laser have been used, and in recent years, semiconductor lasers have come to be used. Since this semiconductor laser generally has an oscillation wavelength in a long wavelength region of 750 nm or more, an electrophotographic photoreceptor having high sensitivity characteristics in the long wavelength region is required, and various proposals have been made. There is. For example, long-wavelength sensitization has also been carried out by adding Ge to an amorphous silicon electrophotographic photoreceptor (Japanese Patent Laid-Open No. 54-54).
98588, 57-172344).

However, when an electrophotographic photosensitive member having sensitivity characteristics in these long wavelength regions is attached to a long wavelength light source, particularly a laser beam scanning type electrophotographic printer, and laser beam exposure is performed, moire is generated in the formed image. Appear,
There is a problem that an image of good quality cannot be formed.

The present invention has been made in view of such problems.

An object of the present invention is to provide an electrophotographic photoreceptor of high image quality in which the occurrence of interference fringes is prevented in a laser printer using coherent light such as an infrared semiconductor laser as a light source.

Another object of the present invention is to provide a highly durable electrophotographic photoreceptor having a photosensitive layer having high adhesiveness, mechanical strength and hardness, excellent surface smoothness and few defects.

Still another object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity, rich in colorimetric property, high charging property, low dark decay, and low residual potential after exposure.

[Means and actions for solving the problem]

In order to achieve the above-mentioned object, the inventors of the present invention have conducted extensive studies on antireflection materials, and as a result, those obtained by dispersing metal powder in an organic polymer compound or an inorganic polymer compound passed through the photosensitive layer. The present invention was found to efficiently absorb and scatter coherent light and to have an excellent antireflection function, and completed the present invention.

The electrophotographic photoreceptor of the present invention comprises at least a support and a photosensitive layer of an antireflection layer, and the antireflection layer is made of an organic polymer compound or an inorganic polymer compound in which a metal powder is dispersed.

In the electrophotographic photosensitive member of the present invention, the metal powder dispersed in the organic polymer compound or the inorganic polymer compound in the antireflection layer is a group IIA element, a group IIB element, II of the periodic table.
Elements selected from Group IA and transition elements, or 2
Alloys or mixtures of one or more elements are preferably used.

These metal powders are ambipolar in that they can flow both positive and negative charges, and the antireflection layer containing them is ambipolar and affects the residual potential of the photoconductor. Less is.

 Hereinafter, the present invention will be described in detail.

1 to 5 are schematic cross-sectional views of the electrophotographic photosensitive member of the present invention. FIG. 1 shows an example of the basic layer structure of the electrophotographic photosensitive member of the present invention, in which an antireflection layer 2 and a photosensitive layer 3 are laminated on a support 1. Second
In the figure, a surface layer is provided on the surface of the photosensitive layer. In FIG. 3, an intermediate layer 5 is provided between the antireflection layer 2 and the photosensitive layer 3, and a surface layer 4 is provided on the surface. 4 and 5, the photosensitive layer has a layer structure in which the charge generation layer 3a and the charge transport layer 3b are functionally separated. In FIG. 4, the antireflection layer 2 is formed on the support 1. ,
It has a structure in which an intermediate layer 5, a charge transport layer 3b, a charge generation layer 3a and a surface layer 4 are sequentially laminated. In FIG. 5, the charge transport layer 3b, the antireflection layer 2 and the charge are provided on a support 1. It has a structure in which the generation layer 3a and the surface layer 4 are sequentially laminated.

In the present invention, any of a conductive support and an insulating support may be used as the support. Examples of the conductive support include aluminum, stainless steel, nickel, metals such as chromium and alloys thereof, and examples of the insulating support include polyester, polyethylene, polycarbonate, polystyrene, polyamide, polymer films or sheets such as polyimide, and the like, Examples include glass and ceramics. When an insulating support is used, it is necessary that at least a surface in contact with another layer has been subjected to a conductive treatment. The conductive treatment can be performed by vapor deposition, sputtering, or ion plating of gold, silver, copper or the like in addition to the above metals.

In the electrophotographic photoreceptor of the present invention, irradiation of electromagnetic waves may be performed from the side of the support or from the side opposite to the support. In the case where the treatment is performed from the support side, the thickness of the metal layer formed by the conductive treatment may be at least enough to transmit the applied electromagnetic wave. Further, a transparent conductive film such as ITO can be used.

In the electrophotographic photosensitive member of the present invention, an antireflection layer and a photosensitive layer are formed on a support. When the photosensitive layer is divided into a charge generation layer and a charge transport layer, the antireflection layer is It may be provided between the charge generation layer and the charge transport layer.
However, when the antireflection layer is provided on the charge generation layer, the antireflection layer is not sufficiently transparent so as to sufficiently transmit electromagnetic waves (light) and reach the lower charge generation layer during exposure. However, since the antireflection layer in the invention is transparent, it can be advantageously used in such a case.

As described above, the antireflection layer is formed by dispersing metal powder in an organic polymer compound or an inorganic polymer compound.

As the metal powder, an element selected from group IIA elements, group IIB elements, group IIIA elements, and transition metals of the periodic table is used. II Be, Mg, Ca, Sr, B as group A elements
a, Ra, IIB group elements include Zn and Cd, IIIA group elements include Al, Ga, In and Tl, and the transition element Sc is the main transition element. To Cu, Y
To Ag, Hf to Au, and internal transition elements La to Lu and Ac to Lr. Among these, Al, Zn, In and main transition elements can be preferably used.

As these metal powders, those having absorption in the wavelength range of the laser used can be selected and used.

The particle size of these metal powders is preferably smaller than the film thickness of the antireflection layer, and particularly preferably 1/2 or less of the film thickness of the antireflection layer. Specifically, 50Å to 5μ
m, preferably 0.01 μm to 0.5 μm. If the particle size is smaller than 50Å, the light scattering ability is deteriorated, and if it is larger than 5 μm, the surface property on the outermost surface of the photoconductor is deteriorated, resulting in poor cleaning and poor resolution.

Further, this antireflection layer can be imparted with a function of smoothing the surface of the support, and in that case, powder having a particle size smaller than the surface roughness of the support may be used.

The organic polymer compound in the antireflection layer may be an electrically active polymer compound such as polyvinylcarbazole or an electrically inactive polymer compound. Examples of the polymer compound that can be used include polyvinyl carbazole, acrylic resin, polycarbonate resin, polyester resin, vinyl chloride resin, fluorine resin, polyurethane resin, epoxy resin, unsaturated polyester resin, polyamide resin, and polyimide resin. Among them, when forming the photosensitive layer by the plasma CVD method, a curable resin is preferable from the viewpoint of heat resistance, mechanical strength and adhesiveness.

In order to form an antireflection layer using the organic polymer compound, the metal powder is dispersed in an organic solvent solution of an organic polymer compound or a liquid organic polymer compound, and the resulting dispersion is applied. , Just dry.

Further, as the inorganic polymer compound in the antireflection layer, an inorganic polymer compound formed of a silicone resin or an organic metal compound can be used.

When the inorganic polymer compound is, for example, a liquid silicone resin, the metal powder may be dispersed therein, and the dispersion liquid may be applied and dried.

When the antireflection layer is formed by the sol-gel method, it can be formed as follows.

_{Si (OCH 3) 4, Si} (OC 2 H 5) 4, Si (OC 3 H 7) 4, Si (OC 4 H 9) 4, Al (OCH 3) 3, Al (OC 2 H 5) 3, _{al (OC 4 H 9) 3} , Ti (OC 3 H 7) 4, Zr (OC 3 H 7), Ti (OC 3 H 7) 4, Y (OC 3 H 7) 3, Y (OC 4 H 9 ) ₃ , Fe (OC ₂ H ₅ ) ₃ , Fe (OC ₃ H ₇ ) ₃ , Fe (OC ₄ H ₉ ) ₃ , Nb (OCH ₃ ) ₅ , Nb (OC ₂ H ₅ ) ₅ , Nb (OC _{3 H 7) 3, Ta (OC} 3 H 7) 5, Ta (OC 4 H 9) 4, Ti (OC 3 H 7) 4, V (OC 2 H 5) 3, V (OC 4 H 9) 3 , etc. Alcohol compounds and organometallic complexes of iron-tris (acetylacetonate), cobalt-bis (acetylacetonate), nickel-bis (acetylacetonate), copper-bis (acetylacetonate), etc. in alcohol Dissolve and hydrolyze with stirring. In the sol liquid generated by the reaction, the above metal powder is dispersed, and the obtained dispersion liquid is applied on a support by a spray method or an immersion method, and after removing the solvent, heated at 50 to 300 ° C for 1 to 24 hours. By drying, an antireflection layer mainly composed of an inorganic polymer compound can be obtained.

The ratio of the metal powder and the organic polymer compound or the inorganic polymer compound is arbitrarily determined by the particle size and resistivity of the powder, the strength of the film, and the film thickness, but usually the weight ratio is 2/98 to 90 / Ten
Is preferable. When the proportion of the metal powder is lower than 2% by weight, the antireflection function is insufficient and the residual potential is high, and when it is higher than 90% by weight, the strength of the film is lowered and the photosensitive layer is lowered. After being laminated, peeling occurs and the function as a photoreceptor cannot be achieved.

The thickness of the antireflection layer is 0.1 to 20 μm, preferably 0.2 to 10
It is set in the range of μm.

In the present invention, the antireflection layer is capable of retaining charges in the dark, and when the charges are generated in the photosensitive layer by irradiation with electromagnetic waves, the charges are quickly injected to support the support. Alternatively, charges can be transferred to the charge generation layer. Further, when the antireflection layer is provided directly on the support, even if the support is insulative, it has sufficient conductivity in the dark and can have a function as a conductive support. .

Further, in the present invention, the antireflection layer can transport both positive and negative charges, so that the photoreceptor can be used by being positively charged or negatively charged.

The photosensitive layer may be formed by forming an inorganic substance such as amorphous silicon, selenium, selenium arsenide, or selenium tellurium by a method such as CVD, vapor deposition, or sputtering. Also, phthalocyanine, Cu phthalocyanine, Al phthalocyanine, V phthalocyanine, square phosphoric acid derivative,
A low molecular weight charge transfer agent is bonded to a charge generation layer formed by vapor-depositing a colorant or pigment such as merocyanine or a bisazo dye or dispersing them in a binder resin into a thin film by a method such as dip coating or spray coating. It is possible to use a laminate of a charge transport layer formed by being dispersed in a resin.

In the present invention, when a selenium-based or a-Si-based photosensitive layer such as Se-Te is provided as an upper layer, it is advantageous in terms of abrasion resistance and abrasion resistance as compared with the case where an organic photosensitive layer is used. In particular, the a-Si photosensitive layer has a high hardness and is extremely advantageous as the outermost surface layer. Therefore, the a-Si photosensitive layer effectively functions as a surface layer from the above viewpoint.

Among them, when hydrogenated amorphous silicon, hydrogenated amorphous silicon added with germanium, or hydrogenated amorphous germanium is used, the photosensitive layer exhibits excellent mechanical and electrical characteristics. In particular, those containing silicon or germanium as a main component and containing 1 to 40 atom%, particularly 5 to 30 atom% of hydrogen are preferable.

In the present invention, since the antireflection layer can be used in either positive or negative polarity, the a-Si type photosensitive layer is most suitable as the photosensitive layer. This is because the a-Si film is formed by adding a group V element or a group III element of the periodic table of elements into the film.
Type, i-type, and p-type films can be easily formed, and when a positively charged type photoreceptor is desired, a p-type a containing a Group III element is added.
-Si photosensitive layer may be used, and when a negative charging type photoreceptor is desired, a V group element may be added or the n-type a-
The i-type a-Si photosensitive layer can be obtained by adding a trace amount of a group III element when a bipolar photosensitive material is desired. This is because the charging polarity of can be controlled.

In the present invention, as a preferable example of the photosensitive layer, the photosensitive layer is composed of a charge generation layer and a charge transport layer, and the charge generation layer and the charge transport layer are mainly composed of silicon, and hydrogen and halogen. In the case of containing at least one element selected from oxygen, nitrogen, carbon and germanium.

Hereinafter, the case where hydrogenated amorphous silicon is used as the photosensitive layer will be described as an example.

The photosensitive layer containing amorphous silicon as a main component can be formed by a known method. For example, it can be formed by glow discharge decomposition, sputtering method, ion plating method, vacuum vapor deposition method, or the like. These film forming methods are appropriately selected according to the purpose, but a method of glow discharge decomposition of silane or a silane-based gas by a plasma CVD method is preferable, and according to this method, 1 to 40 atomic% is contained in the film. A film containing hydrogen, which has a relatively high resistance and a high photosensitivity, is formed, and suitable characteristics as a photosensitive layer can be obtained.

Hereinafter, the plasma CVD method will be described as an example. Examples of the raw material gas for forming the photosensitive layer containing silicon as a main component include silanes such as silane and disilane. Further, when forming the photosensitive layer, it is possible to use a carrier gas such as hydrogen, helium, argon or neon, if necessary. A dopant gas such as diborane (B ₂ H ₆ ) or phosphine (PH ₃ ) gas can be introduced into these source gases to add impurities such as boron or phosphorus into the film. Further, for the purpose of increasing photosensitivity, an element such as halogen, carbon, oxygen or nitrogen may be contained.
Furthermore, it is also possible to add elements such as germanium and tin for the purpose of increasing the sensitivity in the long wavelength region.

The thickness of the photosensitive layer is 5 to 100 μm, preferably 10 to 70 μm
It is set in the range of m.

In the present invention, an intermediate layer may be provided between the antireflection layer and the photosensitive layer or the charge generation layer or the charge transport layer for the purpose of preventing charge injection and improving adhesiveness.

The intermediate layer can be formed by applying a solution of an organic polymer compound such as polyamide, polyimide, or polyester, or an alkoxy compound such as silicon, titanium, or zirconium, followed by drying. In addition, Si by plasma CVD
It is possible to use N _x , SiC _x , SiO _x films, SiO _x , AlO _x , ZnO _x , ZrO _x films by PVD method such as ion plating.

Further, the electrophotographic photoreceptor of the present invention may be provided with a surface protective layer in order to prevent alteration of the surface due to corona ions. Plasma CV is used as the material for the surface protection layer.
Examples thereof include silicon oxide by the method D, silicon carbide, silicon nitride, amorphous carbon, alumina oxide by the ion plating method, and a transparent organic polymer film in which an organic low molecular compound or conductive fine powder is dispersed.

〔Example〕

 Next, the present invention will be described with reference to examples.

Example 1 On a cylindrical aluminum pipe (Rmax = 0.05 μm),
Polyurethane resin (Kansai Paint Co., Ltd., Retan 4000) 50
50 parts by weight of Ni powder having an average particle size of 0.3 μm or less and 15 parts by weight of a solvent (retan thinner, manufactured by Kansai Paint Co., Ltd.) were added to the parts by weight, and mixed and dispersed for 20 hours using a ball mill to prepare a curing agent (retan curing agent 7 parts by weight of Kansai Paint Co., Ltd. was added to the solution by spray coating and dried at 150 ° C for 24 hours to give a thickness of 5
A μm antireflection layer was formed.

The aluminum pipe on which only the antireflection layer was formed was placed in the vacuum chamber of the capacitively coupled plasma CVD apparatus.
The substrate temperature was maintained at 200 ° C, and 100% silane (Si
H ₄ ) gas 100 cc / min, 100% ppm diborane (B
₂ H ₆ ) gas was flowed in at 100 cc per minute, the pressure inside the reaction tank was maintained at 0.5 Torr, and high frequency power of 13.65 MHz was applied to cause glow discharge, and the power was maintained at 100 W. Thus, a charge injection blocking layer having a film thickness of 2 μm and made of so-called p-type amorphous silicon containing hydrogen and a very small amount of boron was formed. Then, change the hydrogen diluted diborane gas to 1cc per minute,
A 20 μm photoconductive layer of so-called i-type amorphous silicon was formed.

Subsequently, the chamber was evacuated to a high vacuum, SiH ₄ 30 sccm and NH ₃ 30 sccm were introduced into the reactor and discharged at 50 W to form a 0.1 μm SiN _x film, thus preparing an electrophotographic photoreceptor.

The obtained electrophotographic photosensitive member was inserted into a semiconductor laser beam printer (XP-9, manufactured by Fuji Xerox Co., Ltd.) and subjected to a print test. As a result, a good image free of moire patterns was obtained.

Comparative Example 1 A charge injection blocking layer, a photoconductive layer and a surface layer were formed in exactly the same manner as in Example 1 without providing an antireflection layer on an aluminum support mirror-cut with Rmax = 0.05 μm. When a print test was performed using the same printer as in Example 1, a so-called moire pattern having a wood pattern appeared on the entire screen,
The image quality was significantly reduced.

Example 2 On an aluminum flat plate, 40 parts by weight of a ceramic coating agent (ceramica 1100, manufactured by Nichiban Kenkyusho Co., Ltd.) and a particle size of 0.1 to
Add 50 parts by weight of 0.5 μm copper powder and use a ball mill to 1
Mix and disperse for 00 hours, add 10 parts by weight of a curing agent, dilute the coating solution, and apply by dip coating method.
After drying for an hour, an antireflection layer having a thickness of 4 μm was formed.

On the antireflection layer, the same photosensitive layer as in Example 1 was provided to prepare a photoconductor, and a print test was carried out with a laser beam printer. As a result, a clear image free from moire was obtained.

Example 3 On an aluminum pipe having a surface roughness Rmax of 0.5 μm,
The same antireflection layer as in Example 2 was provided. The surface roughness of this antireflection layer was 0.05 μm or less in Rmax.

An electrophotographic photosensitive member was prepared by providing the same photosensitive layer as in Example 1 on this antireflection layer, and a print test was carried out by a laser beam printer. As a result, a clear image free from moire was obtained. Good images with no defects were obtained even after printing 100,000 sheets repeatedly.

Comparative Example 2 The same photosensitive layer as in Comparative Example 1 was provided on the same support as in Example 3 to prepare a photosensitive member, and a print test was performed. When a print test was performed on 10,000 sheets, a moire pattern appeared in the image, and white spots and black spots increased with repeated copying operations, resulting in a marked deterioration in image quality.

Example 4 The same antireflection layer and charge blocking layer as in Example 1 were provided on an aluminum support, and silane gas 150 sccm, ethylene gas 5 sccm, and hydrogen-diluted diborane gas were mixed on the aluminum support so that the diborane concentration was 10 ppm with respect to the silane gas. , Pressure 1.0
By processing with Torr and high-frequency power of 150 W, a charge transport layer having a film thickness of 15 μm and made of carbon-doped amorphous silicon was formed. Further, i-type amorphous silicon was formed thereon under the same conditions as in Example 1 so as to have a film thickness of 0.5 μm.
Subsequently, silane gas 160sccm, germane gas 40sccm,
Hydrogen-diluted diborane gas was mixed so that the concentration of diborane was 2 ppm with respect to the total amount, and the mixture was treated with a pressure of 1.0 Torr and a high-frequency power of 150 W to form a charge generation layer made of amorphous germanium silicon. A surface layer was provided thereon under the same conditions as in Example 1 to prepare an electrophotographic photosensitive member.

When a print test was carried out with a laser beam printer using this electrophotographic photosensitive member, a print having an excellent density contrast of an image free of moire was obtained.

〔The invention's effect〕

Since the electrophotographic photosensitive member of the present invention is provided with a layer made of an organic polymer compound or an inorganic polymer compound in which a metal powder is dispersed as an antireflection layer as described above, a printer using a coherent light such as a laser as a light source. In, the occurrence of interference fringes can be prevented and the occurrence of moire can be prevented, and a high quality image can be obtained.

[Brief description of the drawings]

1 to 5 are schematic cross-sectional views of the electrophotographic photosensitive member of the present invention. 1 ... Support, 2 ... Antireflection layer, 3 ... Photosensitive layer, 3a ...
... Charge generation layer, 3b ... Charge transport layer, 4 ... Surface layer, 5 ...
... intermediate layer.

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Claims (4)

(57) [Claims] 1. An electrophotographic photoreceptor comprising at least a support, an antireflection layer and a photosensitive layer, the antireflection layer comprising an organic polymer compound or an inorganic polymer compound in which a metal powder is dispersed. 2. A metal powder comprising an element selected from a group IIA element, a group IIB element, a group IIIA element and a transition element of the periodic table,
Alternatively, the electrophotographic photosensitive member according to claim 1, comprising an alloy or a mixture of two or more of these elements. 3. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer is mainly composed of amorphous silicon and / or amorphous germanium. 4. The photosensitive layer is composed of a charge generation layer and a charge transport layer, and the charge generation layer and the charge transport layer are mainly composed of silicon, and hydrogen, halogen, oxygen, nitrogen, carbon, The electrophotographic photosensitive member according to claim 1 or 2, wherein the electrophotographic photosensitive member contains any one element selected from germanium.