JPH0287149A - electrophotographic photoreceptor - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor that has a photosensitive layer with excellent durability and has little deterioration in image quality due to edge reversing. Regarding photoreceptors.

[Prior Art] In recent years, many electrophotographic photoreceptors using organic compounds as photoconductors have been developed. Most of those that have been put into practical use have a form in which the photoconductor is mechanically dispersed into a charge-generating material and a charge-transporting material.

Such an electrophotographic photoreceptor using an organic photoconductor is
It is said to have the advantage of high productivity due to the good film formation properties of the photosensitive layer, and is also expected to have even better electrophotographic properties such as sensitivity and photoresponsivity due to its flexibility in material design. There is.

By the way, since an electrophotographic photoreceptor is repeatedly used in an electrophotographic apparatus and undergoes various image forming processes, the photoreceptor is required to maintain stable characteristics. However, when using an electrophotographic photoreceptor using an organic photoconductor repeatedly, it is said that image quality deterioration is likely to occur, such as a decrease in image density due to a decrease in band clarity, and image blurring due to a decrease in surface resistance. It has its drawbacks.

The influence of corona discharge is considered to be one of the causes of image deterioration. That is, when the photoreceptor is used in a copying machine, it is constantly exposed to an atmosphere of corona discharge, and as it performs green copying, it is exposed to organic light due to active species such as ozone generated by corona discharge. It is thought that the conductor deteriorates. In addition, electrophotographic photoreceptors using organic photoconductors are often used with negative charges, and in this case, negative corona charging generates more ozone than positive corona charging, so they are used with positive charges. It is thought that this type of photoreceptor deteriorates more easily than other photoreceptors.

Conventionally, it has been proposed to add various antioxidants as a method of preventing the above-mentioned deterioration of electrophotographic photoreceptors (Japanese Unexamined Patent Publications No. 57-12244'4, JP-A-58-1).
No. 20260, JP-A-61-156131,
JP-A-62-105151).

[Question 8] Accordingly, an object of the present invention is to provide an antioxidant that further improves prevention of image quality deterioration and does not adversely affect other electrophotographic properties.

[Means for Solving the Problems] According to the present invention, in an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor, the photosensitive layer contains a compound represented by the following structural formula (1) and a structural formula (1). An electrophotographic photoreceptor characterized by containing the compound represented by (2) is provided.

y.

X is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkenyl group having 1 to 10 carbon atoms] [wherein, R is a hydrogen atom or a halogen atom, and x, 1, and x4 are 1 to 1 carbon atoms;
-10 alkyl group or an alkenyl group having 2 to 10 carbon atoms] The present invention will be described in detail below.

Examples of the halogen atom represented by R in the structural formula (2) include F, CI, Br, and I.

In the present invention, the photosensitive layer containing an organic photoconductor includes a charge generation layer containing a single-layer charge generation material containing a mixture of a charge generation material and a charge transport material that are functionally separated; It takes the form of a laminate type in which a charge transport layer containing a charge transport material is laminated.

Examples of charge-generating materials include biryllium, thiopyrylium dyes, phthalocyanine pigments, anthoanthrone pigments,
Organic pigments such as perylene pigments, dibenzpyrenequinone pigments, biracitron pigments, azo pigments, indigo pigments, and quinacridone pigments are used.

As charge transport materials, pyrazoline type, stilbene type,
Triphenylamine type, benzidine type.

Oxazole-based, indole-based, carbazole-based compounds, etc. are used.

In the case of a single-layer type photoreceptor, the above-mentioned charge generating material and charge transporting material are appropriately dispersed and dissolved in a binder resin, and this is applied onto a conductive substrate to form a photosensitive layer.

Further, as a multi-layer type photoreceptor, there are two types of conductive photoreceptors: one in which a conductive layer (v1) is layered in the order of (1) a charge generation layer and a charge transport layer, or (2) one in which a charge transport layer and a charge transport layer are laminated in that order. In the case of j↓1, methods for forming the charge generation layer include a method of dispersing and dissolving the charge generation material and the binder resin in a solvent and applying the mixture, as well as methods such as vapor deposition and sputtering.The charge transport layer is A charge transport material and a binder resin are dispersed and dissolved in a solvent and then laminated on the charge generation layer.In this case, the structure represented by the structural formula (1)
.

It is preferable that the charge transport layer contains the compound represented by (2).

In the case of ■, the charge transport material and binder resin are dispersed in a solvent,
A charge transport layer is formed by dissolving and coating, and a charge generating material and a binder resin are dispersed in a solvent on the layer.

A charge generation layer is formed by dissolving and coating. At this time.

It is preferable that the charge-generating layer also contains a charge-transporting material. In this case, the compound of structural formula (1) or (2) is preferably contained in the charge-generating layer or both the charge-generating layer and the charge-transporting layer. is suitable.

In the present invention, an antioxidant having four hindered phenol groups (a compound represented by the above structural formula (1))
and an antioxidant having a benzotriazole group (a compound represented by the above structural formula (2)). These two types of antioxidants have little effect when used alone, or they exhibit sufficient effects when used together.Containing compounds of formula (1) and formula (2) The total amount is preferably 0.2 to 20% by weight, more preferably 0.5 to 15% by weight, based on the weight of the photosensitive layer (charge generation layer and/or charge transport layer in the case of a laminated type). . The content (A) of the compound of formula (1) and the formula (
The ratio (A)/(B) of the content (B) of the compound in 2) is preferably l/1 to l/0.1 (weight ratio), 01
71 to 110.3 (weight ratio) is more preferable.

If the total content is less than 0.2% by weight, the deterioration prevention effect tends to be reduced, and if it exceeds 20% by weight, it tends to cause F5 effects such as decreased sensitivity and increased residual potential.

The mechanism of preventing deterioration of the photosensitive layer by ozone and the active substances generated therewith is mainly expressed by the hindered phenol group and the benzotriazole group, but the effect is largely due to the synergistic effect of the reoxidation inhibitor.

The photosensitive layer of the present invention further includes a lubricant for reducing abrasion.
Known additives such as surface modifiers, plasticizers for improving flexibility, etc. may also be included.

Examples of the conductive substrate include known ones, such as cylindrical or belt-shaped aluminum, iron, copper, or metal-deposited plastic films. In addition, an adhesive layer, a barrier layer, an adhesive layer, a barrier layer,
Intermediate layers such as parallel layers may also be provided.

[Example] Next, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 A 5% methanol solution of polyamide resin (trade name: Ami 920M-8000, manufactured by Toshi) was applied to it by immersion, using an O7 aluminum cylinder with a diameter of 80 cm and a length of 360 layers as a conductive substrate. , an undercoat layer with a thickness of 0.5 JLm was formed.

Next, 10 parts of trisazo pigment having the following structural formula (overlapping parts, the same shall apply hereinafter) were added to polyvinyl butyral resin (trade name: S-LEC BL-
3.m (manufactured by Suikagaku Co., Ltd.)) and 50 parts of cyclohexanone were dispersed using a sand mill apparatus using 1φ glass beads.

To this dispersion, 100 parts of methyl ethyl ketone was added and applied onto the undercoat layer to form a charge generation layer with a thickness of 0.2 gm.

Next, 10 parts of a stilbene compound having the following structural formula was added to a polycarbonate resin (trade name: Penlight L-1250, manufactured by Ondai Kasei).
10 parts dichloromethane 50 parts monochlorobenzene 10 parts
A charge transport layer coating solution was prepared. Tetrakis-[methylene-3-(3', 5°
-di-tert-butyl-4'-hydroxyphenyl)
Pyrovionate comethane (THPM-1) and 2-
(2'-Hydroxy-3°, 51-di-tert-butylphenyl)benzotriazole (BZT-1) was added at a weight mixing ratio of 1/1, a total of 0.4 parts and 2.0 parts, respectively. 0.5/1 added as described above,
Further, the mixture added as described above at a mixing ratio of 1/Q and 5 was used and coated on the charge generation layer to form a charge transport layer having a thickness of 18 JLm. The photoreceptors thus produced are referred to as photoreceptors 1, 2, 3, 4, and 5.6, respectively. Furthermore, for comparison, THPM-1, BZT with a mixing ratio of 1/1 and an additive amount of 6 parts, a comparison without additives, and a comparison with THPM-1 and BZT.
Photoreceptor 7, 8, 9.10 with 2.0 parts of -1 added alone
It was created.

These photoreceptors were installed in an electrophotographic copying machine, and their characteristics were evaluated as follows. First, the dark potential of the photoreceptor (VD
) and bright area potential (Vt, ) are -650V and -15, respectively.
1tii conditions were set so that the voltage was 0V. The image exposure amount at that time was determined, and the potential after 5,000 sheets of M continuous copying was performed in row 9 using the 0th order as the initial sensitivity was determined, and the rate of decrease in VO and increase in VL were determined. After that, the photoreceptor with the part located directly under the corona i'1 electric device marked was left in the copying machine for 10 hours during the exposure time, and the surface potential of the marked part and other parts was measured, and the difference (ΔVO ) was sought. The results are shown in Table 1.

Next, photoreceptors were prepared with various additive mixing ratios and additive amounts, and similar evaluations were conducted. The results are shown in Table 2.

The addition amounts shown in the table are based on the added photosensitive layer, that is,
Here, it is the ratio to the weight of the charge transport layer.

As is clear from Tables 1 and 2, for the photoreceptor not containing the compounds of formulas (1) and (2), the dark area t was significantly reduced by repeated electrophotographic processes. Moreover, the effect was small when using only one of the compounds of Formula 1 (1) and Formula 1 (2).

On the other hand, photoreceptors with appropriate content and mixing ratio of the compound of formula (1) and compound of formula (2) are superior, with significantly less decrease in charge value, and no adverse effects in practical use were observed. Ta. Furthermore, when the amount added was 25% by weight, the bright area potential increased.

Example 2 10 parts of a disazo pigment having the following structural formula as a charge generating material.

Polyvinyl butyral resin (product name: S-LEC BX-
1, manufactured by Miki Kagaku) and 50 parts of cyclohexanone were dispersed in a sand mill apparatus using glass beads. To this dispersion, 792,100 parts of tetrahydrochloride was added and coated on the same substrate and undercoat layer as in Example 1.
, m thick charge generation layer was formed.

Next, as a charge transport material, 0.72 parts of a benzcarbazole compound (2°-hydroxy-3′, 5°-di-tert-acylphenyl)benzotriazole (BZT-2) having the following structural formula was added at a mixing ratio of 1/l. A solution prepared by dissolving 15 parts of dichloromethane and 45 parts of monochlorobenzene was applied onto the above charge generation layer to form a charge transport layer having a thickness of 18 parts m. This will be referred to as photoreceptor-21.

On the other hand, for comparison, a sample to which neither THPM-2 nor BZT-2 was added was prepared and used as the photoreceptor 22. Furthermore, a photoreceptor containing the additives shown in Table 3 was prepared as a comparative sample.

8 parts, styrene-acrylic copolymer resin (trade name: Estyrene MS-200 manufactured by Nippon Steel Chemical)>10 parts, and tetrakis-[methylene-3 (3°, 5° terL-acyl-4′-hydroxyphenyl)propylene onate comethane (THPM-2), 2-The characteristics of these photoreceptors were evaluated in the same manner as in Example 1.
The amount of light when +' V L was set to -650 V and -150 V, respectively, was also measured. These results are shown in Table 4.

Table 4 As shown in Table 4, the deterioration prevention effect of the combined use of the compounds of Formula 1 (1) and Formula 1 (2) is clear, and at the same time, the use of other antioxidants alone or in combination with other antioxidants It can be seen that either sufficient effects cannot be obtained or other negative effects are significant.

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

Next, a solution prepared by dissolving 15 parts of a stilbene compound of the following structural formula and 10 parts of BO (trade name: Panlite L-1250, manufactured by Kijin Kasei) in 50 parts of dichloromethane and 210 parts of monochlorobenza was applied onto the undercoat layer for 15 JLm. A thick charge transport layer was formed.

Next, 4 parts of a disazo pigment having the following structural formula, and 7 parts of a stixystilbene compound described in +iii.

Next, 1 part of a disazo pigment having the following structural formula, 10 parts of the bocker carbonate resin, THPM-Pl, B
0.63 parts of ZTII mixing ratio 1/1, 1 part of dichloromethane
A coating solution prepared by decomposing and dissolving 1 part in 50 parts of monochlorobenzene was spray-coated on the above-mentioned charge transfer plate, and 5 parts m
A thick charge generation layer was formed. This will be referred to as a photoreceptor 30.

On the other hand, photoreceptor 3 without adding THP) i-1 and BZT-1
1 was created. To positively charge these photoreceptors, Vo =+
The voltage was set to 650V, Vt, = +150V, and the following evaluation was conducted in the same way as in the conventional case.

The results are shown in Table-5.

Example 4 In the same manner as in Example g11, apply a lower coating on the substrate < lO part of the benzcarbazole compound used in Example 2, polycarbonate resin (trade name: Vanlite L-1250)
, manufactured by Teijin Chemicals) 10 parts, tetrakis-[methylene-3 (
3°-tert-aluminum-5'-tert-butyl-
4°-hydroxyphenylcomethane (THPM-3),
2-(2'-hydrocin-3'-tert-acyl-
A coating material dispersed and dissolved in 5'-tert-butylphenyl)benzotriazole (BZT-3), 60 parts of dichloromethane, and 20 parts of monochlorobenzene was applied onto the above undercoat layer to create a photosensitive layer with a thickness of 16 #Lm. .

This will be referred to as a photoreceptor 32. On the other hand, for comparison, THPM-3
A photosensitive layer without addition of /BZT-3 is formed, and this is used as a photoreceptor 33.

These photoreceptors were evaluated in the same way as in Example 3, and the results are also listed in Table 5.

Table 6 Table 5 Example 5 Using the compounds shown in Table 6 as antioxidants, the mixture ratio was 1/
A photoreceptor was prepared in the same manner as in Example 1, except that the amount added was 10%.

Table 6 Continued Table 7 Table 8 shows the results of similar evaluations for the photoreceptors shown in Table 7.
Shown below.

Table 8 Example 6 Regarding photoconductors 2.8 and 21 prepared in Examples 1 and 2, after 5000 copies were made in the characteristic evaluation described above,
An additional 45,000 copies were made. As a result, for the photoreceptor 2.4 to which an antioxidant was added, even after the 500-sheet durability test, there was no deterioration in image quality compared to the initial stage, and images with stable high contrast and no unevenness were obtained. On the other hand, photoreceptor 8 of the comparative sample to which no antioxidant was added
The decrease in image density became noticeable around 15,000 sheets. In addition, the potential drop that occurs when the printer is left in rest after copying is complete results in extremely uneven images.

Additives used in Examples (TIIPM-1 to 6, BZTl
The structures of ~6) are summarized in Table 9.

Table 9 (Continued) 9 (Continued) [Effects of the Invention] As described above, the electrophotographic photoreceptor of the present invention has extremely high potential stability in a corona discharge environment and always forms stable, high-quality images. Something will happen. The present electrophotographic photoreceptor can also be used as a photoreceptor for printers that apply electrophotography, such as laser beam printers, LED printers, LED printers, LCD printers, and CRT printers, in addition to ordinary copying machines.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive substrate, in which the photosensitive layer contains a compound and a structure represented by the following structural formula (1). Formula (2)
An electrophotographic photoreceptor characterized by containing a compound represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (1) [In the formula, 10 alkyl group or alkenyl group having 2 to 10 carbon atoms] ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (2) [In the formula, R is a hydrogen atom or a halogen atom, and X_3 and X_4 are carbon atoms 1 to 10 Alkyl group or carbon number 2
-10 alkenyl groups] 2. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer is a stack of a charge generation layer and a charge transport layer. 3. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer consists of a single layer containing a charge generating material and a charge transporting material. 4. Compounds represented by structural formula (1) and structural formula (2)
) The total content of the compounds represented by ) is 0.2 to 20% by weight based on the weight of the photosensitive layer contained.
The electrophotographic photoreceptor described above. 5. Ratio of the content (A) of the compound represented by structural formula (1) to the content (B) of the compound represented by structural formula (2) (
5. The electrophotographic photoreceptor according to claim 1, wherein A)/(B) is 0.1/1 to 1/0.1 (weight ratio).