JPH01961A - electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] A surface protective layer suitable for forming good images.

That is, amorphous carbon containing hydrogen and fluorine (hereinafter referred to as a)
The present invention relates to an electrophotographic photoreceptor that has both high moisture resistance and high hardness by specifying the amount of F/C in a film (referred to as -C:F:H).

[Conventional technology]

Conventionally, S e and CdS have been used as electrophotographic photoreceptors.
.

Inorganic photoconductive material such as AszSea or PVK-TNF
Organic photoconductive materials, such as those typified by, are used. Although these materials have extremely excellent electrophotographic properties, it cannot be said that their mechanical properties necessarily satisfy the required specifications. In contrast, amorphous silicon photoreceptors have excellent properties in both photoconductivity and mechanical properties. However, the only drawback is poor moisture resistance. The reason for this is that hydrophilic SiOx (x=1 to 2) is generated on the surface of the photoreceptor due to ozone generated during corona charging. Due to the high hardness of the surface, it cannot be removed even with fur brushes, magnetic brushes, etc., and the S on the surface increases with repeated corona charging.
i Ox production increases. Therefore, in order to improve moisture resistance, it is necessary to minimize the amount of SiOx produced. Therefore, a method of making the surface non-Si may be considered. Based on this point of view, there is a method using amorphous carbon as seen in Japanese Patent Application Laid-Open No. 61-94056. However, amorphous carbon (a-Cor A-C'
:') I) C= due to ozone generated during corona charging
It is easy to form a carbonyl group of 0, making it easy to get wet with water.

For corona charging, a film containing elements with stronger bonding force than an amorphous carbon film is required.

On the other hand, the patent using C-F bond is USP 4,582,7
As shown in No. 69, when simply using an a-C:F:H film, films with various bζ composition ratios (F/C) can be considered. F
When /C is small, C=0 is formed due to ozone generated during corona charging, similar to an a-c (or a-C:H) film, and it becomes easy to wet with water. Therefore, unless an appropriate F/C is specified, the reproducibility of preventing image blurring will be poor and it cannot be put to practical use.

[Problem that the invention seeks to solve]

The conventional technology has not sufficiently dealt with the reaction product, which has an adverse effect under high humidity, such as the formation of SiOx by corona. An object of the present invention is to provide an electrophotographic photoreceptor whose surface is protected with a compound of C, F, and H, thereby preventing oxidation due to corona and having high moisture resistance.

[Means for solving problems]

Since the a-C:F:H film formed on the surface of the photoreceptor is not easily oxidized even during corona charging, the surface can be maintained highly water-repellent even under high humidity, and images without blurring can be produced.

Further, by setting the F/C atomic ratio to 0.4 or more and 2 or less, high humidity resistance and corona resistance were significantly improved.

In the present invention, it is highly desirable that the surface protective film contains 30 atomic % or less of silicon.

This increases hardness and improves durability. The silicon content is particularly preferably in the range of 5 to 20 JI%.

[Effect]

As a means of making the surface water repellent, there is a CFa plasma treatment method. but.

When this method is applied to this material, the surface is etched. Therefore, in the present invention, H2 was added to the CFa plasma to combine C, F, and H decomposed in the plasma. By producing a highly water-repellent a-C:F:H film on the surface of the photoreceptor, it is possible to create a photoreceptor that does not blur.

〔Example〕

Example (1) Crystalline Si plate and glass plate (Corning 7059) as substrates
The film was formed using a radio wave (13,56 MHz) discharge device. The reaction gas is CF4, +H2 mixed gas ratio (X=H2/(CF4+Hz)) from O to 1.0.
changed to. The reaction gas pressure was ITorr, the discharge voltage was 50 W, the substrate temperature was 200° C., and the substrate was placed on the ground electrode. FIG. 1 shows the relationship between gas ratio (X) and film formation rate. As can be seen from this figure, when X<0.1, the substrate is etched at a negative film formation rate. However, when X≧0.1, the film is formed on the substrate at a positive film formation rate. FIG. 2 shows the relationship between the corona irradiation time and the contact angle with water for the a-C:F:H film prepared with X≧0.1. Corona irradiation was performed using an electrostatic recorder (SSV-II) manufactured by Kawaguchi Electric at +5.5 KV and room temperature (
As can be seen from Figure 0, which was performed at 23℃) and 50 to 60% RH, the contact angle decreases with corona irradiation time no matter which gas ratio is used, but the rate of decrease increases as the gas mixture ratio increases. I know what will happen. Therefore, a-C:F:H
A laminated photoreceptor with a film as a surface protective layer was prepared and a printing experiment was conducted. The printer used for printing is a semiconductor laser (780
nm) is used. Print density was measured as image evaluation. Note that printing was performed at 25° C. and 80% RH under high humidity.

The photoreceptor film structure used in the experiment is as shown in Figure 3.
a-SiC on top drum: H (0.5 μm)/a-Si
:H(B)(30μm)/a-8iGe(0.5μm
) was laminated, and then a 0.5 μmM a-C:F:H film was applied as a surface protective layer. The results of repeated printing are shown in FIG. In either case.

This is the result of printing every 5 hours of corona irradiation. As can be seen from this figure, there was no decrease in print density even after 15 hours of corona irradiation in the drums manufactured with a gas ratio of 0.1 to 0.5. However, drums made with a gas ratio of 0.7 or higher were irradiated with corona for 15 hours.
Afterwards, image blurring occurred and the print density decreased to about 0.8. Therefore, next, a-C:F:H was prepared with various gas ratios.
The F/C ratio of the film was analyzed using photoelectron spectroscopy (XPS).

The results are shown in Figure 5. F/C decreases parabolically with respect to gas ratio. From Figures 4 and 5, F/
It can be seen that C is 0.4 or more and 2.0 or less.

On the other hand, CF n (n = 1 t
2.3) Considered binding. FIG. 6 shows an example of a film prepared with X=O,l analyzed by photoelectron spectroscopy (XPS). When the spectrum seen near the binding energy of 285 eV is divided into peaks, as shown in the figure, C-C and C-Fn(n
=1.2.3) It can be seen that a bond exists.

Among these bonds, the best bond is CFz. That is, C-Fz has a two-dimensional chain structure, while C-Fs means the end point of the C-C bond.

When C-F z, the probability that the C-C bond can take the diamond bond state increases. Therefore, the surface hardness of the a-C:F:H film increases.

Example (2) This time, the substrate microwave (2.45 GHz) is emitted! An experiment similar to Example (1) was conducted in the apparatus.

The microwave discharge output was 160 W, and the sample was set at a position 1301 below the cavity to prevent the sample from being directly exposed to the discharge sphere. As in Example 1, the film formation mode was set at X≧0.1. . This film also had a
-C:F:H film was found by XPS analysis. In image evaluation of a photosensitive drum using this film as a surface protective layer, the same effect as in Example 1 was obtained with F/C≧0.4.

Example (3) Next, hydrogen fluoride carbon gas containing H was used as a reaction gas. An example is CHFa gas. In this case, no matter which discharge device of Example (1) or (2) is used, the gas ratio (Y = Hz/ (Hz + CHF a)) is Y =
The film is deposited at a deposition rate ranging from 0 to positive. The results are shown in FIG. 7. Furthermore, in the image evaluation of an electrophotographic photoreceptor using this film as a surface protective layer, the same effect as in Example 1 was obtained when F/C≧0°4.

From Examples 1 and 2.3, if a fluorocarbon-based gas containing F is used as a fluorine source during film formation, F in the film can be reduced regardless of the type of fluorine.
It has been found that image deletion can be prevented by specifying the amount of /C. Therefore, in a-C:F:H system pus with an F/C content of 0.4 or more, this membrane contains P, N, O,
Even if B or the like is doped up to a maximum of 10 at %, the effects of the present invention will not be interfered with. Further, the amount of hydrogen as bonded hydrogen is usually about 0.5 to 1 oat%, and even if this hydrogen has a positive effect on the effects of the present invention, it will not cause any harm.

This is clear from the fact that the aC:H film is also effective against image deletion.

Example (4) Si was added to the a-C:F:H film, and changes in the contact angle due to the amount of Si and corona irradiation were investigated. Based on the zero image evaluation, if the lower limit of the contact angle was set to 45°, even after 15 hours of corona irradiation. 40-45
The amount of Si that maintains the temperature above 30at is shown by curve a in Figure 8.
% or less. This is because Si becomes Sin due to corona irradiation.

(x = 0 to 2), the contact angle substantially maintains the required minimum value as long as there is a highly water-repellent C-F bond and the conditions of F/C≧0.4 are satisfied. It means that.

Example (5) When the cause was devised, it was found by xPS analysis that SiH decreased and SiO generation increased. Therefore, it is best to use a bond with a larger bond energy than SiH, such as @SiF or SiC, which can be expected to improve the contact angle by preventing the formation of SiO. S in place of S i H4 gas as a reaction gas during film fabrication.
i When produced using F4 gas, a-C:F:H
It has been found that the Si incorporated into the film forms SiF bonds or SiC bonds. Therefore, the relationship between the contact angle after corona irradiation and the amount of Si added was determined under the same conditions as in Example (4). The results are shown in the curve in Figure 8. As can be seen from this figure, a higher contact angle can be obtained than in Example (4). In this case, it is understood that the amount of Si can be added up to 30 at%. Adding Si in this manner improves surface hardness and increases durability.

[Effects of the Invention] According to the present invention, a corona-resistant and moisture-resistant photoreceptor can be produced with good reproducibility, and as a specific effect, a printer or a copying machine that maintains high printing quality even under high humidity can be provided.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing the relationship between film formation rate and gas ratio. Figure 2 is a characteristic diagram showing the relationship between contact angle and corona irradiation time.
Figure 3 is a cross-sectional view showing the photoreceptor film structure, Figure 4 is a characteristic diagram showing the relationship between print density and corona irradiation time, and Figure 5 is F/
A characteristic diagram showing the relationship between C and gas ratio. FIG. 6 is a characteristic diagram showing the C1s spectrum, FIG. 7 is a characteristic diagram showing the relationship between film formation rate and gas ratio, and FIG. 8 is a characteristic diagram showing the relationship between contact angle and Si amount. 1... AQ substrate, 2... Blocking layer, 3...
Charge transport area 1 concave 2nd bacterium os to ts corona layer I facing v'% (h) Fig. 4 ugly eye; corona 4 o'clock 1 season () L) Leather 51. ¥1 Oθ, / 0,3 θ, so, 't
θ, 9th force strikes and 6th mouth 2'? 5 ZqO2B5 280 Yoshishin Keikoberu (eV) 70 rate 8 figure

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a photoconductive layer made of amorphous silicon and a support for the photoconductive layer, an amorphous carbon film containing hydrogen and fluorine on the outermost surface of the photoreceptor. 1. An electrophotographic photoreceptor characterized in that the film has an atomic ratio of F/C of 0.4 or more and 2 or less. 2. An electrophotographic photoreceptor comprising a photoconductive layer made of amorphous silicon and a support for the photoconductive layer, having an amorphous carbon film containing hydrogen, fluorine, and silicon on the outermost surface of the photoreceptor, The amount of silicon in the film is 30
An electrophotographic photoreceptor characterized in that the F/C atomic ratio is 0.4 or more and 2 or less. 3. Electrophotography according to claim 2, characterized in that silicon is bonded in the state of Si-F and/or Si-C in the amorphous carbon film containing hydrogen, fluorine, and silicon. Photoreceptor.