JPH0661004B2 - Photoconductor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoconductor that is unlikely to cause scratches or scrapes on its surface.

BACKGROUND ART Photoreceptors used in electrophotographic copying machines and the like are rubbed against copy paper,
The surface is likely to be scratched or scraped due to rubbing with a blade. The scratches and scrapes cause development such as the generation of black spots on the copy paper and the generation of shear marks, and are important factors that control the life of the luminescent material.

These scratches and abrasions are particularly likely to occur in photoconductors obtained by binding a photoconductive material onto a conductive substrate with a binder resin, and therefore the life of these photoconductors is generally around 20,000 copies. Is. If the photoconductor has low lubricity, the blade member itself may be worn and damaged.

In order to solve the above problems, a photoconductor in which the surface of a photoconductive layer formed of a binder resin is coated with a lubricating resin layer, for example, polytetrafluoroethylene or the like to improve wear resistance has been proposed. (JP-A-58-182637). However, even these photoreceptors do not necessarily have satisfactory abrasion resistance against Al ₂ O ₃ and SiO ₂ contained in the paper powder of copy paper.

Therefore, as the surface overcoat layer, Al ₂ O ₃ or Si is used.
Surface coating having hardness equal to or higher than O ₂ ,
For example, it is possible to form SiC, SiO _2, etc., but these are not necessarily sufficient in terms of lubricity.

Problems to be Solved by the Invention The performance required for the overcoat layer for protecting the surface of the photoconductor is excellent in abrasion resistance, hard to be scratched, and good in lubricity, in addition to the characteristics of the photoconductor itself. It is necessary not to damage. For example, an overcoat layer having poor light transmittance lowers the sensitivity of the photoreceptor. Further, it is necessary to easily form a uniform thin film. Further, the overcoat layer is required to have high adhesion strength with the photoconductive layer.

It is an object of the present invention to provide a photoreceptor having an overcoat layer which satisfies these requirements.

Means for Solving the Problems The present invention provides SiO ₂ , AI ₂ O ₃ , Si ₃ N,
An overcoat layer having a thickness of 0.05 to 0.5 μm made of at least one inorganic compound selected from SiC and TiO ₂ , and a thickness of 0.05 to 0.5 made of Ta ₂ O _5.
The present invention relates to a photoconductor characterized by being sequentially laminated with a μm overcoat layer.

Ta ₂ O ₅ has a high hardness, relatively high transparency, leave enough wear resistance at a thickness that does not affect the sensitivity of the photosensitive member, by Al ₂ O _3, SiO ₂ or the like in the paper dust The photoreceptor can be protected from scratches and damages caused by rubbing with the blade. Further, since the lubricity is higher than that of the SiO ₂ film or the like, the wear resistance is further improved. The thickness of the Ta ₂ O ₅ thin film is 0.05 to
0.5 μm is suitable. If it is thinner than 0.05 μm, the function as a protective film is deteriorated, and if it is thicker than 0.5 μm, the light transmittance becomes insufficient, resulting in a decrease in sensitivity and a phenomenon such as image fog.

The Ta ₂ O ₅ overcoat layer may be any type of photoconductor, for example, a Se-based photoconductor, a Cds-based photoconductor, an OPC-based photoconductor (a photoconductor obtained by binding an organic photoconductive substance with a binder resin). ) Etc., but with particularly low abrasion resistance
A high effect can be obtained when used for the C photoconductor. However, depending on the type of binder resin used in the OPC photosensitive member, the adhesiveness of Ta ₂ O ₅ is low, and therefore peeling may occur easily. For example, even if acrylic resin, polycarbonate resin or the like widely used as a binder resin is coated with Ta ₂ O ₅ by a vacuum deposition method, a sputtering method, an ion plating method or the like, a high adhesion strength cannot be obtained.
Therefore, an inorganic compound having excellent adhesiveness to the binder resin is previously coated, and then Ta ₂ O ₅ is coated thereon. Inorganic compounds that can be used for this purpose include SiO ₂ and AI ₂
O ₃ , Si ₃ N, SiC, TiO _{2 and the} like are exemplified. These may be appropriately selected according to the type of resin. These layers have a function of protecting the surface of the photoconductor similarly to the outermost surface layer of Ta ₂ O _5, and are therefore referred to as a second overcoat layer. If the second overcoat layer is too thick, the residual potential increases,
It should be 0.5 μm or less. If the thickness of the second overcoat layer is less than 0.5 μm, the adhesion effect becomes insufficient.

The total thickness of the outermost overcoat layer and the second overcoat layer should not exceed 1 μm. Preferably the total thickness of both layers is 0.1 to 0.5 μm.

As a method for forming the overcoat layer (including the second overcoat layer), a vacuum vapor deposition method; a plasma CVD method using glow discharge, a sputtering method, an ion plating method, or the like may be used. Since the hardness of the formed thin film is insufficient, glow discharge is preferable. When glow discharge is used, high-energy ions of the compound used can be formed, and the adhesion is improved, so that a dense overcoat layer can be formed.

Further, a high-frequency ion plating method is generally adopted in the ion plating method. However, in this conventional method, glow discharge is relatively generated in the vicinity of the photoconductive layer.
In an OPC photosensitive member using an organic photoconductive material having an absorption band in the wavelength range of 00 to 500 nm, the charging layer may be damaged by light having a large wavelength range generated by glow discharge. Therefore, in such a photoreceptor, the first
As shown in the figure, the photoconductor (1) and the ionizer (7) and
(8) is provided relatively distant from each other, a deposition material such as Ta ₂ O ₅ is arranged in the vicinity of the ionization device, and vaporized particles from this evaporation source or gas from the gas introduction port is stored in the ionization device. Ionization under a direct current electric field, the ionized particles are accelerated under a direct current electric field between the above ionizer and the photoconductor,
It is advisable to employ a method such as by adhering it to the surface of the photoconductive layer of the photoconductor.

As long as the photoreceptor of the present invention has a layer of Ta ₂ O _{5 on} the outermost surface, the constitution of the lower layer is arbitrary, and various conventionally used modes can be adopted. For example, a single layer type having a single photoconductive layer, a function separation type in which the photoconductive layer is divided into a carrier generation layer and a carrier transport layer, and a photoconductor having a charge injection prevention layer between the conductive support and the photoconductive layer. It can be applied to various photoconductors.

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

Example 1 (1) Preparation of Photoconductive Paint: 50 parts by weight of copper phthalocyanine and 0.2 parts by weight of tetranitrocopper phthalocyanine were dissolved in 500 parts by weight of 98% concentrated sulfuric acid with sufficient stirring, and this was poured into 3000 parts by weight of water.
After depositing a photoconductive material composition of copper phthalocyanine and tetranitrocopper phthalocyanine, it was washed with water and dried at 120 ° C. under reduced pressure.

22.5 parts by weight of a thermosetting acrylic resin (Acrydeic A405: manufactured by Dainippon Ink Co., Ltd.) and 10 parts by weight of the obtained composition, 7.2 parts by weight of a melamine resin (Super Beckamine J820: manufactured by Dainippon Ink Co., Ltd.) , Hydrazone compounds (1)
A photoconductive coating was prepared by adding 15 parts by weight together with 70 parts by weight of methyl isobutyl ketone: cellosolve acetate (1: 1) into a ball mill pot and kneading for 48 hours.

(2) Formation of Photoconductive Layer The above coating composition was applied on an aluminum substrate so as to have a thickness of about 15 μm. This was dried and cured at 150 ° C. to form a photoconductive layer. The product itself can be used as a photoreceptor, and therefore, it was used as a comparative example in the evaluation test described below.

(3) Formation of Second Overcoat Layer SiO ₂ was deposited on the photoconductive layer using an ionization plating device as shown in FIG. 1 (schematic cross-sectional view).

First, the cylindrical photosensitive drum (1) obtained above was fixed to the upper part of the vacuum container (2) on a horizontal sample mounting shaft (4) rotated by a drive motor (3). The drum (1) was attached and rotated by the drive motor (3) so that the attachment was uniform over the entire surface. On the other hand, SiO ₂ is housed in a grounded copper crucible (5) provided in the lower part of the vacuum container (2) and heated to a high temperature by an electron gun (6) provided in the vicinity of the copper crucible (5). To be evaporated. At this time, when the generated thermoelectrons rush into the ionization electrode (7) (a positive voltage is applied by the voltage source (8)) provided in the vicinity of the copper crucible (5), they collide with vaporized particles and Let the particles be positively charged ionic particles. The vaporized particles are accelerated in ionization by thermoelectrons generated from a thermoelectron emission electrode (14) (comprising a tungsten filament) provided between the copper crucible (5) and the ionization electrode (7). The ion particles are accelerated toward the photoconductor drum (1) by a DC electric field formed between the ionization electrode (7) and the photoconductor drum (1) to which a negative voltage is applied by the voltage source (9). , Adhere to the surface of the photoconductor. Since the surface of the photoconductor is heated by the heater (15) arranged in the vicinity of this (of course, it is heated to a temperature that does not adversely affect the photoconductor), the film growth property on the surface of the photoconductor is improved. To do. The vacuum container (2)
Is provided with a gas introduction system (10), which is used when a film is formed by a chemical reaction on the surface of the photoconductor with the introduced gas. Further, the thermionic emission electrode (14) and the heater (15) may not be provided.

The conditions adopted in the above operation were as follows.

Electron beam: 100mA Ionization voltage: 10V / mm Degree of vacuum: 1 × 10 ^-4 torr Distance between copper crucible and photoconductor: 80cm Substrate voltage (photoconductor): -800V Thermoelectron emission (tungsten filament φmm, 2600 ° K) 8V-60A Substrate temperature (photoreceptor surface temperature heated by heater (15) at 150 ° C.): time: 3 minutes Under the above conditions, a photoreceptor having a SiO ₂ second overcoat layer having a thickness of 0.2 μm was obtained. . This photoreceptor was subjected to the evaluation test described later for comparison.

(4) Formation of Ta ₂ O ₅ surface overcoat layer: Ta ₂ O ₅ was applied to the outermost surface under the following conditions, using the same apparatus as that in which the second overcoat layer was provided.

Electron beam: 200mA Ionization voltage: 10V / mm Vacuum degree: 1 × 10 ^-4 torr Distance between copper crucible and photoconductor: 80cm Substrate voltage (photoconductor): -800V Thermionic emission (tungsten filament φ1mm, 2600 ° K) 8V-60A Substrate temperature: 150 ° C. Time: 2 minutes The obtained photoreceptor of the present invention has a photoconductive layer (12) and a second overcoat layer (12) on a conductive support (11) as shown in FIG. 1
3), and a 0.15 μm Ta ₂ O ₅ overcoat layer (14).

(5) Evaluation Test of Photoreceptor On the conventional photoreceptor (photoreceptor A) having no overcoat layer, photoreceptor (receptor B) having SiO ₂ second overcoat layer and SiO _{2 obtained} above. A photoconductor having the Ta ₂ O ₅ surface overcoat layer (photoconductor of the present invention) was attached to an EP350E copying machine manufactured by Minolta Camera Co., Ltd., and an actual copying test was carried out to make the following evaluations.

Cleanability: Judgment was made based on the number of black spots generated when 2000 sheets were copied.

Blade durability: The number of copies until the blade becomes abnormal.

Occurrence of scratches on the photoconductor: The number of copies until the photoconductor is scratched.

The above results are shown in Table-1.

EFFECTS OF THE INVENTION The photoreceptor of the present invention has a highly hard Ta ₂ O ₅ overcoat layer having excellent lubricity and adhesiveness on the outermost surface, resulting in blade scratches, abrasion due to friction with copy paper, blade damage, etc. Is less likely to occur and the cleaning property is high.

[Brief description of drawings]

FIG. 1 is an example of an apparatus for producing the photoconductor of the present invention, and FIG. 2 is a schematic sectional view of the photoconductor of the present invention. (1) ... Photosensitive drum, (2) ... Vacuum container, (8) ... Ionizing electrode, (10) ... Gas introduction system, (11) ... Conductive support, (12) ... Photoconductive layer, (13) … Second overcoat layer, (14)… Overcoat layer.

Claims (1)

[Claims] 1. SiO ₂ , AI ₂ O ₃ , and Si ₃ on the photoconductive layer.
At least one selected from N, SiC and TiO _2.
0.05-0.5 μm thick overcoat layer made of one kind of inorganic compound and Ta ₂ O ₅ thickness 0.05-
A photoreceptor comprising a 0.5 μm overcoat layer sequentially laminated.