JPH01219754A - Photosensitive body - Google Patents

Abstract

PURPOSE:To facilitate adjustment of volume resistivity of a surface protective layer and to obtain a photosensitive body having high abrasion resistance, moisture resistance, ozone resistance, etc., by laminating a photoconductive layer and a surface protective layer on an electroconductive substrate of an electrophotographic sensitive body, coating an alumina sol on the surface protective layer, and forming a surface protective layer by calcining the coated alumina sol. CONSTITUTION:An Al pipe 1 fitted to a surface of a cylinder having a revolutional axis 1a in the center is used as a supporting body of an electroconductive body of an electrophotographic sensitive body. Amorphous selenized As is coated by vapor deposition with a vacuum deposition device on the surface of the Al pipe 1 to form thus a photoconductive layer 2. Then, a surface protective layer 3 is formed on the electroconductive layer 2 to prepare thus a photosensitive body 4. An alumina sol prepd. by diluting, if necessary, an alumina sol with water or with a mixture of water with alcohol, is applied in the stage of forming the protective layer 3 to the surface of the electroconductive layer 2 by coating, etc. Thus, a protective layer 3 is formed by calcining the coated alumina sol at high temp.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a photoreceptor used in electrophotography, etc., which is formed by laminating at least a photoconductive layer and a surface protection layer on a conductive support. This relates to photoreceptors.

[Prior art and its problems] Conventionally, in photoreceptors used in electrophotography, inorganic photoconductive materials such as selenium, cadmium sulfide, zinc oxide, and amorphous silicon have been used as photoconductive materials constituting the photoconductive layer. conductive materials, polyvinyl carbazole, phthalocyanine, trinitrofluorein, bisazo pigments.

Organic photoconductive materials such as hydrazone were commonly used.

However, regardless of whether the above-mentioned inorganic or organic photoconductive materials are used for the photoconductive layer, if such a photoconductive layer is exposed on the surface of the photoreceptor, However, when this photoreceptor is repeatedly used over a long period of time, the surface of the photoconductive layer is affected in various ways, and its characteristics gradually deteriorate.

For example, when a corona charger or the like repeatedly discharges the surface of the photoconductive layer in order to charge the photoreceptor, ozone and nitrogen oxides generated at this time cause crystallization near the surface of the photoconductive layer. There is a problem in that the basic characteristics of photoreceptors such as charge retention ability and sensitivity are deteriorated due to the photoreceptor's basic properties such as charge retention ability and sensitivity.

In addition, the surface of the photoconductive layer may be damaged during the cleaning process, which removes residual toner adhering to the surface of the photoconductive layer after transfer using a fur brush or blade cleaner that rubs against the surface of the photoconductive layer. In addition, there were problems such as the photoconductive layer being gradually scraped away and becoming thinner, resulting in deterioration of the function of the photoconductive layer. In particular, when a blade cleaner that presses the surface of the photoconductive layer is used, a so-called filming phenomenon occurs in which toner is embedded in the surface of the photoconductive layer, further shortening the life of the photoreceptor.

Therefore, in order to improve these problems, conventionally, a surface protection layer called a so-called protective layer or an electrically insulating layer has been provided on the surface of the photoconductive layer.

Here, in providing such a surface protective layer,
In order to prevent the residual potential on the photoreceptor from increasing,
Usually, it is necessary to adjust the volume resistivity to 10 9 to 10 13 Ω·Ω.

For this reason, in the past, as such a surface protective layer, -ffl is made of a metal oxide such as tin oxide and antimony oxide in a binder resin, as shown in JP-A-57-128344. A film containing a metal filler was formed on the photoconductive layer E.

However, the volume resistivity of the surface protective layer is increased to 109 by incorporating a filler of metal oxide, typically tin oxide-antimony oxide, which usually has a resistivity of 105 Ω or less.
When adjusting to ~1013 Ω・cm, it is difficult to control the appearance of the filler to be included, and it is very difficult to form a surface protective layer with an appropriate volume resistivity, which tends to increase the residual potential. If the film thickness is made thinner in order to reduce the thickness, there is also the problem that it cannot function satisfactorily as a surface protective layer.

Furthermore, such conventional surface protective layers are not sufficient in terms of abrasion resistance, moisture resistance, ozone resistance, etc., and if the photoreceptor is used repeatedly over a long period of time, this surface protective layer will gradually wear off. There is also a problem in that the function of the surface protective layer and, by extension, the function of the photoreceptor deteriorates as the surface protective layer becomes thinner and thinner.

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and has a surface protective layer that is easy to adjust volume resistivity, and has abrasion resistance, moisture resistance, and ozone resistance. The present invention provides a photoreceptor with excellent electrophotographic properties in general, especially stability over time, etc. by providing the photoreceptor with excellent properties in these respects.

[Means for Solving the Problems] In the present invention, in a photoreceptor in which at least a photoconductive layer and a surface protection layer are laminated on a conductive support,
To form the surface protective layer, alumina sol was applied and fired to form the surface protective layer.

The conductive support used here may be any commonly used one, such as a drum-shaped or plate-shaped one made of aluminum or aluminum alloy, etc.
Various types can be used.

The photoconductive layer to be formed on this conductive support can also be formed by a conventionally commonly used method, and the photoconductive material used for this photoconductive layer can also be Either inorganic or organic photoconductive materials can be used, such as. Furthermore, it is also possible to separate the functions of this photoconductive layer and make this photoconductive layer a laminated type in which a charge generation layer and a charge transport layer are laminated.

Regarding the photoconductive materials used in the photoconductive layer, in order to suppress the decrease in sensitivity due to ozone generated during corona discharge, etc., selenium such as Nicelene trioxide, selenium-tellurium, and various amorphous seleniums are used. It is preferable to use a type material.

Next, to form a surface protective layer on the photoconductive layer, the alumina sol is diluted with water or a water-alcohol mixture as necessary, and then diluted with water or a water-alcohol mixture, and then subjected to a dipping method, a spray method, a spinner method, or a blade method.

After coating on the photoconductive layer using various coating methods such as roller method and Mayer bar method, it is dried at high temperature to precipitate polymerized particles of aluminum compounds such as aluminum hydroxide and aluminum oxide. Do it like this.

The aluminum sol used here contains an appropriate amount of alumina hydrate (boehmite type) consisting of a colloid with an appropriate particle size, and has a milky white color in which polymer particles of (AI-0) are dispersed with acidic anions as a stabilizer. Make sure to use a liquid with a certain viscosity. The colloidal particle size of this alumina hydrate is adjusted to maintain a stable water dispersion state.
It is desirable to use particles with a particle size of 10 to 1000 particles. In addition, if the amount of this alumina hydrate is too small, it will not function sufficiently as a surface protective layer.
On the other hand, if this amount is too large, the stability of the colloidal solution will deteriorate and it will tend to settle, and there is also the risk of causing an increase in the residual potential in the surface protective layer.
~20% by weight.

After coating such an aluminum sol on the photoconductive layer, drying is carried out at a high temperature of 100°C or higher in order to change the state from a sol to a gel. It is necessary to carry out the process at a temperature that does not change.

In addition, regarding the thickness of this surface protective layer, if it is made too thin, it may be easily worn away by cleaning, etc. On the other hand, if it is made too thick, there is a risk that residual potential may accumulate and increase. Thickness 0.5-5μm
It is preferable to keep it at a certain level.

In addition, in such a surface protective layer, in order to adjust the volume resistivity, it is also possible to add a conductive filler as needed, and this conductive filler includes, for example, tin oxide.

Zinc oxide, indium oxide, titanium oxide, iron powder, etc. can be used. In addition to this, hydroxyl groups are added to adjust its volume resistivity.

It is also possible to add an organic polymer having a polar group such as an amine group or a carboxyl group, or to add a surfactant such as a quaternary ammonium salt or a phosphate ester.

[Function] In a photoreceptor in which at least a photoconductive layer and a surface protective layer are laminated on a conductive support in this way, when forming the surface protective layer, alumina sol is applied and baked, resulting in a smooth and smooth surface. A surface protective layer made of a fine alumina film that has excellent abrasion resistance, moisture resistance, and ozone resistance can now be obtained.

Further, the volume resistivity of this surface protective layer can be easily adjusted, and the increase in residual potential can also be easily suppressed.

Furthermore, since the alumina sol used to form this surface protective layer is an aqueous dispersion, it can be processed into a thin film and smoothed, and it is also easy to handle, making it easy to form the surface protective layer. become.

[Example] Next, specific examples of the present invention will be described, and comparative examples will be given to clarify that the photoreceptor according to the example of the present invention is superior.

In this example, as shown in FIG. 1, a cylindrical aluminum tube (1) having a rotating shaft (1a) at the center was used as the conductive support.

A photoconductive layer (2) is then formed on the surface of the aluminum tube (1).
A known vacuum evaporation device is used to form the
A photoconductive layer (2) was formed by evaporating and depositing amorphous arsenic selenide on the surface of this aluminum tube (1) using a vacuum evaporation method. The photoconductive layer (2) can also be formed by a sputtering method, an ion blasting method, or other generally known PVD methods.

Next, in forming the surface protective layer (3) on this photoconductive layer (2), 7% by weight of alumina hydrate particles having a particle shape of 1000 x 100 particles are used as alumina sol.
A coating solution having a viscosity of 20 CPS was prepared by diluting this feather-like alumina sol (Nialumina Silu 200, manufactured by Nissan Chemical Company, Ltd.) with methanol.

This coating solution is then applied to the photoconductive layer (
2) After coating on top, dry at 160°C for 3 hours in a constant temperature bath to form a surface protective layer (3
), and a photoconductive layer (2) and a surface protective layer (3) are laminated on the surface of an aluminum tube (1).
I got it.

Note that the volume resistivity of the surface protective layer (3) formed as described above was approximately 10<13>Ω·Ω.

Example 2 - In this example as well, a photoconductive layer (2) was formed on the surface of an aluminum tube (1) in the same manner as in Example 1 above.

To form the surface protective layer (3) on this photoconductive layer (2), an alumina sol containing 5% by weight of alumina hydrate (manufactured by Kuyoken Fine Chemicals: Alumina Clear Sol) was used. A tin oxide-antimony oxide solid solution (manufactured by Mitsubishi Metals ■: T-1) was added as a conductive filler at a ratio of 5% by weight, and after dispersing them by a known method, this was sprayed. The photoconductive layer (2)-A was coated.

Thereafter, as in the case of Example 1 above, this was dried in a constant temperature bath at 160°C for 3 hours until the average film thickness was 3.
．． A surface protective layer (3) of 5 μm was formed. The volume resistivity of the surface protective layer (3) thus formed is as follows:
It was about 101Ω・am.

Supervision 1 Eclipse Also in this comparative example, in the same way as each example described in ■,
A photoconductive layer (2) was formed on the surface of the aluminum tube (1).

In this comparative example, the above photoconductive layer (2)
To form the surface protective layer (3) on top, 100 parts by weight of polycarbonate resin and a tin oxide-antimony oxide mixture with a particle size of 0.1 μm (manufactured by Mitsubishi Metals Co., Ltd.: T-1>
Grind 40 parts by weight and 210 parts by weight of trichloroef.
After dispersing, this was used to form a 2 μm thick surface protection layer (3) on the surface of the photoconductive layer (2).The volume resistivity of the surface protection layer (3) thus formed was as follows: IQI
The variation was 1Ω・cm.

In addition, in this comparative example, the surface smoothness of the surface protection layer deteriorated due to the low resistance filler, and it was also difficult to adjust the volume resistivity. In addition, for this reason, the surface protective layer has poor charge retention when charged, and charges are injected into the photoconductive layer, which tends to impair resolution.

Next, the photoreceptors of Examples 1 and 2 and Comparative Examples formed as described above were mounted in a copying machine, and a normal electrophotographic process consisting of positive corona discharge, exposure, development, transfer/separation, and erasing was carried out. I decided to do it.

For each photoconductor, when the number of copies is 0 and when the number of copies is 10
The charge potential and residual potential 1 image quality after copying 100,000 copies were measured, as well as the amount of decrease in the thickness of the surface protective layer after copying 100,000 copies, and the results are summarized in Table 1 below. In the same table, good image quality is indicated by ◯, slightly degraded image quality is indicated by Δ, and poor image quality is indicated by ×.

Table 1 As is clear from the results, each of the photoconductors according to the examples of the present invention, like the photoconductor of the comparative example, showed a significant increase in residual potential and a decrease in image quality after copying 100,000 copies. Furthermore, the surface protective layer will not be scratched and thinned by cleaning or the like.

As a result, the characteristics of each photoreceptor according to the embodiments of the present invention do not change even when used for a long time, and stable images can be obtained over a long period of time.

[Effects of the Invention] As detailed above, in the photoreceptor according to the present invention, in forming the surface protective layer on the photoconductive layer, alumina sol is applied and then baked to form the surface protective layer. As a result, the volume resistivity can be easily adjusted, the increase in residual potential can be easily suppressed, and a surface protective layer with excellent wear resistance, moisture resistance, ozone resistance, etc. can be obtained. Now you can.

As a result, the photoreceptor according to the present invention has the best electrophotographic properties, and in particular, even when used for a long time, its properties do not change, making it possible to obtain stable images over a long period of time. .

[Brief explanation of the drawing]

FIGS. 1 and 2 are a perspective view and a sectional view of photoreceptors according to an example of the present invention and a comparative example. (1)...Aluminum tube (conductive support) (2)...
...Photoconductive layer (3)...Surface protective layer (4)...
・Photoreceptor

Claims (1)

[Claims] 1. A photoreceptor comprising at least a photoconductive layer and a surface protective layer laminated on a conductive support, characterized in that the surface protective layer is formed by applying alumina sol and firing the same. photoreceptor.