JPH0266556A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a sensitive body and to improve the electrophotographic characteristics by incorporating a specified basic compd. into the photosensitive layer by 0.05-10wt.% of the total amt. of the layer. CONSTITUTION:A photosensitive layer contg. an org. photoconductor is formed on an electrically conductive substrate and a compd. represented by formula I (where X is -S-, -S-S, etc., and each of R1 and R2 is H, 1-10C alkyl, etc.) is incorporated into the photosensitive layer by 0.05-10wt.% of the total amt. of the layer. The photosensitive layer may contain a mixture of electric charge generating and transferring materials having separated functions to obtain a single layer type sensitive body or the photosensitive layer may be composed of an electric charge generating layer contg. an electric charge generating material and an electric charge transferring layer contg. an electric charge transferring material to obtain a laminate type sensitive body. Very high potential stability under corona discharge is ensured and a stable high quality image can be formed at all times.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a highly durable photosensitive layer that does not deteriorate image quality even after repeated use. Regarding photoreceptors.

[Prior Art] In recent years, many electrophotographic photoreceptors using organic compounds as photoconductors have been developed. Of these, most of the ones that have been put to practical use have a form in which the photoconductor is functionally separated into a charge-generating material and a charge-transporting material. Electrophotographic photoreceptors using such organic photoconductors are expected to further improve electrophotographic properties such as sensitivity and photoresponsivity because of their flexibility in material design, and they are also easy to form films and have high productivity. It is characterized by high

Incidentally, an electrophotographic photoreceptor is repeatedly subjected to various image forming processes in an electrophotographic apparatus, and the photoreceptor is required to exhibit stable characteristics during this process. however,
An electrophotographic photoreceptor using an organic photoconductor as described above is
When repeatedly used, it has the disadvantage that image quality deterioration such as uneven image density due to a decrease in charging ability and image blurring due to a decrease in surface resistance is likely to occur.

One possible cause of these deteriorations is the influence of corona discharge. That is, when a photoreceptor is used in a copying machine, it is constantly exposed to a corona discharge atmosphere.
It is believed that the organic photoconductor is degraded by active species such as ozone, NOx, and station 05 generated by corona discharge as copies are repeatedly performed. In particular, electrophotographic photoreceptors using organic photoconductors are often used with negative charges, but in the case of negative corona charging, the amount of ozone generated is greater than with positive charging. This is considered to be one of the factors that makes it more susceptible to deterioration than other photoreceptors used.

Conventionally, it has been proposed to add various antioxidants as a method of preventing the above-mentioned deterioration of electrophotographic photoreceptors (Japanese Unexamined Patent Publication Nos. 57-122444, 1981-1999).
120260, JP 61-156131, JP 62-105151, etc.).

[Problems to be Solved by the Invention] An object of the present invention is to eliminate the above-mentioned drawbacks by adding a specific basic compound to the photosensitive layer of an electrophotographic photoreceptor, that is, to prevent deterioration and to An object of the present invention is to provide an electrophotographic photoreceptor that does not cause any adverse effects on photographic properties.

[Means for solving the ByIA problem] The present inventors investigated the factors of such photoreceptor deterioration, and
As a result of repeated studies on improvement methods, we found that adding a specific basic compound to the photosensitive layer containing an organic photoconductor has a sufficient effect of preventing deterioration, and that it does not adversely affect other electrophotographic properties. The present invention was completed by discovering that it is possible to obtain a photoreceptor that does not cause this phenomenon.

That is, 1 the present invention provides an electrophotographic photoreceptor having a photosensitive layer containing a conductive substrate and an organic photoconductor, wherein the photosensitive layer has a general formula (wherein, X is -s --5-s --(cu2)n - or -(CH-CI()-, in which case n is O~1
R1 and R2 are hydrogen atoms, an alkyl group having from 1 to 10 carbon atoms, or an alkenyl group having from 2 to 10 carbon atoms). 0. based on the total weight of
It is characterized by containing 05 to 10%.

In the electrophotographic photoreceptor of the present invention, the photosensitive layer containing an organic photoconductor is a single-layer photoreceptor in which a functionally separated charge-generating material and a charge-transporting material are mixed, or a charge-generating material is included. It can take the form of a laminated photoreceptor in which a charge generation layer and a charge transport layer containing a charge transport material are laminated.

Charge-generating materials include pyrylium dyes, thiavirilicum dyes, phthalocyanine pigments, and anthorone m.
Organic pigments such as pigments, perylene pigments, dibenzpyrenequinone pigments, vilanthrone pigments, azo pigments, indigo pigments, and quinacridone pigments can be used.

As the charge transport material, pyrazoline type, hydrazone 51.
It is possible to use compounds such as r, tilbene type, triphenylamine type, indigo pigment, oxazole type, indole type, and tyrpazole type.

In the case of a single-layer thermal photoreceptor, the above-described charge-generating material and charge-transporting material are dispersed and dissolved in a solvent together with a suitable binder resin, and the resultant solution is applied onto a conductive substrate to form a photosensitive layer.

On the other hand, in the case of a laminated photoreceptor, (1)
Should the charge generation layer and charge transport layer be laminated in this order?

Or (11) Laminated on the charge transport layer and charge generation layer.

As a method for forming the mixed charge generation layer (1), there is a method in which the charge generation material described above is dispersed and dissolved in a solvent together with a suitable binder resin, and the resulting mixture is coated on a conductive substrate. The charge transport layer is laminated by dispersing and dissolving the charge transport material described above in a solvent together with a suitable binder resin, and coating the entire charge transport material on the charge generation layer. In the case of (1)o, it is preferable that the additive used in the present invention be contained in the charge transport layer.

On the other hand, in the case of (11) above, both layers are
) can be formed in the same way as in the case of In this case, it is preferable that the charge generation layer also contains a charge transport material. In the case of (11), the additive used in the present invention is preferably contained in the charge generation layer or in both the charge generation layer and the charge transport layer.

The additive used in the present invention is a basic compound having two pyridine rings, as shown by the above general formula. Pyridine exhibits weak basicity and can prevent deterioration of the photosensitive layer by capturing acidic deteriorating substances such as f(No. 3. HNO3) generated by corona discharge. 0.05 to 10%, preferably 0.05 to 10%, based on the total weight of the layer, charge transport layer or both).
It is 1 to 5%.

If the amount added is less than 0.005%, the desired deterioration prevention effect will not be achieved, and if it exceeds 10%, sensitivity will decrease,
A negative effect such as an increase in residual potential occurs.

In the present invention, the photosensitive layer may further contain known additives such as lubricants to reduce abrasion, surface modifiers, and plasticizers to improve flexibility.

In the present invention, the conductive substrate may be a known material commonly used in electrophotographic photoreceptors, such as a cylindrical or belt-shaped aluminum, iron, copper, or metal-deposited plastic film.

Further, in the present invention, an intermediate layer such as an adhesive layer, a barrier layer, a smooth layer, etc. can be provided between the conductive substrate and the photosensitive layer, if necessary.

[Examples] Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. In the following description, all parts are by weight.

Example 1 An aluminum cylinder with a diameter of 80 cm and a length of 360 cm was used as a conductive substrate, and a 5% methanol solution of polyamide resin (trade name: Nyaramin CM-8000, manufactured by Tsukun Co., Ltd.) was coated on it by a dipping method. Then, a subbing layer with a thickness of 0.5 μm was provided.

Next, the structural formula was formed.

Next, 10 parts of trisazo pigment represented by the structural formula, 6 parts of polyvinyl butyral resin (trade name: S-LEC BL-8, manufactured by Sekisui Chemical Co., Ltd.)
1 part and 50 parts of cyclohexane were dispersed in a sand mill apparatus using glass beads.

100 parts of methyl ether ketone was added to this dispersion, and the mixture was coated on the undercoat layer, and 10 parts of a stilbene compound represented by a 0.2μ charge generation layer and a polycarbonate resin (trade name Nipanlite L- A coating solution for a charge transport layer was prepared by dissolving 10 parts of No. 1250 (manufactured by Kanairi Kasei) in 50 parts of dichloromethane and 10 parts of monochlorobenzene. 4,
0.02 each of 4'-bipyridyl (DPy -1)
1.8 parts, 0.3 parts, 0.6 parts and 1.8 parts were applied onto the charge generation layer to form a charge transport layer having a thickness of 18μ. The photoreceptors thus prepared are referred to as photoreceptors 1, 2, 3 and 4, respectively. Further, as comparative samples, photoreceptor 5 without DP7-1 added and photoreceptor 6 with DP7-1 added in an amount of 3 parts were prepared.

These photoreceptors were installed in an electrophotographic copying machine, and their characteristics were evaluated as follows. First, the dark potential (VD) and light potential (VL) of the photoreceptor are set to -600V, respectively.
The conditions for the latent image were set to -150V. The image exposure amount at that time was determined and used as the initial sensitivity. Next, the potential was measured after 5000 sheets were continuously copied to determine the rate of decrease in VD and the increase in V.Then, the photoreceptor was left in the copying machine, and the surface potential was measured after 10 hours. did. At this time,
During the standing period, a mark was placed on the portion of the photoreceptor located directly under the corona charger, and the difference (ΔvD) from the other portion was determined. The results are shown in Part 2.

1st surface photoreceptor DP7-1 initial vDvL
Weight Sensitivity Decrease Rate Increase Δv after being left unattended
D (weight%) (lu:caste) (%>
(1(V)1 0.1 3.0
8.5 10 202 1
．． 5 3.1 5.4 15
103 3.0 3.2
4.5 20 104
9.0 3.3 4.0 3
0 105 0 3.0
30.0 10 906 15
3.5 2.2 90
5. The addition amount shown in the table is the ratio (% by weight) to the weight of the photosensitive layer to which DP7-1 was added, that is, in this case, the charge transport layer.

As is clear from Table 1, when the photoreceptor did not contain K or an additive, a significant decrease in dark area potential was observed after repeated electrophotographic processes. Furthermore, if the amount added is too large, there is a problem in that the bright area potential increases significantly. - On the other hand, in the case of a photoreceptor with an appropriate content of additives, the chargeability decreases little, and no practical problems are observed.

Example 2 As a charge generating material, 10 parts of a disazo pigment having the structural formula, 6 parts of polyvinyl butyral resin (trade name: SLEK BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 50 parts of hiscyclohexanone were dispersed in a sand mill apparatus using glass beads. Add 100% of tetrahydrofuran to this dispersion.
A charge generating layer having a thickness of 0.2 .mu.m was formed by coating on the same substrate and subbing layer as in Example 1.

Next, as a charge transport material, 8 parts of a benzcarbazole compound having the structural formula, 10 parts of a styrene-acrylic copolymer resin (trade name Estylane MS-200゜Nippon Steel Chemical Department) and 2.2''-dipyridyl (DP7) were used as charge transport materials.
-2) A solution prepared by dipping 0.36 parts into 15 parts of dichloromethane and 45 parts of heptanochlorobenzene was applied onto the charge generation layer to form a charge transport layer with a thickness of 18μ. This will be referred to as photoreceptor 7.

On the other hand, for comparison, a sample to which DP7-2 was not added was prepared, and this was designated as photoreceptor 8.

The characteristics of these photoreceptors were evaluated in the same manner as in Example 1. In addition, the initial vDvL is -650V, respectively.
, the amount of light when setting the voltage to -150V was also measured.

These results are shown in Table 2.

2nd front photoconductor Initial sensitivity VD decrease rate vL increase Δv after standing
DA (1ux-see) (%) (
V) (V)7 2.9 5
．． 4 25 108 2.8
28.2 20 90 Example 3 An undercoat layer was applied onto the substrate in the same manner as in Example 1.

Next, 15 parts of a stilbene compound with the structural formula and a polycarbonate compound? Nate resin (
A solution prepared by dissolving 10 parts of Panrye (trade name) L-1250 Teijin Kasei M) in 50 parts of zochloromethane and 10 parts of monochlorobenzene was applied onto the undercoat layer to form a charge transport layer with a thickness of 15 μm.

Then the structural formula On the other hand, a photoreceptor 10 was prepared without adding DP7-1.

These photoreceptors were positively charged to 650V.

The voltage was set to VL-+150V, and the following evaluations were conducted in the same manner as in the prior art. The results are shown in Table 3.

Table 3 5.8 35.8 Example 4 An undercoat layer was applied onto the substrate in the same manner as in Example 1.

Next, 4 parts of the disazo pigment having the structural formula, 7 parts of the stilbene compound, 10 parts of the polycarbonate resin, and 0.63 parts of ppy
-1, 150 parts of dichloromethane, 5 parts of monochlorobenzene
A paint dispersed and dissolved in Q'i5 was spray coated onto the charge transport layer to form a charge generation layer with a thickness of 5μ. This will be referred to as photoreceptor 9.

oy, t, yy 1 part of the chemical agent 10 parts of the benzcarbazole compound used in Example 2, 10 parts of polycarbanate resin (trade name Panrai L-1250 manufactured by Teijin Kasei) and 1.2 parts
- Di-2-pyrisol ethane (DP7-3) 0.3 parts was dispersed and dissolved in 60 parts of zochloromethane and 20 parts of monochlorobenzene, and a coating material was applied on the undercoat layer to 16 μm.
A thick photosensitive layer was created. This will be referred to as the photoreceptor 11. On the other hand, for comparison, a DP7-3 photosensitive layer with no additives was formed and used as photoreceptor 12.

These photoreceptors were evaluated in the same way as in Example 3, and the results are shown in Section 4.

4th Table 11 4.0 20
1512 25.5
15 100 Example 5 A photoreceptor was prepared in the same manner as in Example 1 except that a disazo pigment having the structural formula was used as the charge generating material and the compounds shown in Table 5 were used as the additives. In addition, as a comparative example, a photoreceptor without additives was formed, and this was designated as photoreceptor 13.

Table 5 Table 6 shows the results of similar evaluations of these photoreceptors.
Shown in the table.

There was no deterioration in Table 1, and images with stable high contrast and no unevenness were obtained. On the other hand, in the comparison sample Photoreceptor 5 to which no antioxidant was added, the image density decreased significantly after about 15,000 sheets of durability.

Furthermore, due to the potential drop that occurs when the printer is left at rest after copying is completed, the image becomes extremely uneven.

The structures of the additives (DP71-10) used in the above examples are summarized in Table 7.

Example 6 For photoreceptors 2.5 and 7 prepared in Examples 1 and 2, after 5000 copies were made in the characteristic evaluation described above, an additional 45000 copies were made.

As a result, the image quality of photoreceptors 2 and 7 to which antioxidant had been added was found to be higher than the initial image quality even after 500 sheets were used. It has extremely high stability and can always form stable, high-quality images.

In addition to ordinary copying machines, this electrophotographic photoreceptor can also be used in laser beam printers, LED near-syp-LCDs, etc.
l:2゜Linter It can also be used as a photoreceptor in printers that apply electrophotography, such as CRT printers.

Procedural amendment February 6, 1999 Commissioner of the Japan Patent Office Yoshi 1) Takeshi Moon 1.Display of the incident Patent Application No. 1983-216249 2. Name of the invention electrophotographic photoreceptor 3. Person who makes corrections Relationship with the incident Name 4. Agent

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor having a photosensitive layer containing a conductive substrate and an organic photoconductor, the photosensitive layer has a general formula ▲A mathematical formula, a chemical formula, a table, etc.▼ (In the formula, X is -S-, -S-S-, -(CH_2)_n
-, or -(CH=CH)_n-, in which case n
is an integer from 0 to 10, R_1 and R_2 hydrogen atoms,
Alkyl group having 1 to 10 carbon atoms or 2 to 10
0.05 to 10 carbon atoms, based on the total weight of the layer to which it is added.
An electrophotographic photoreceptor characterized by containing %.