JPH0254272A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve durability and to decrease deterioration of image quality by repetitive use by incorporating a specific compd. into a photosensitive layer. CONSTITUTION:The compd. expressed by the formula I is incorporated into the photosensitive layer of the electrophotographic sensitive body having the photosensitive layer into which an org. photoconductor is incorporated on a conductive base body. The photosensitive layer contg. the org. photoconductor attains the form of a lamination type or the like laminated with a charge generating layer contg. a single layer type charge generating material into which a function separated charge generating material and charge transfer material are incorporated in a mixed state and a charge transfer layer contg. the charge transfer material. The laminated type photosensitive body includes the photosensitive body formed by laminating the charge generating layer and the charge transfer layer in this order or the photosensitive body formed by laminating the charge transfer material layer and the charge generating layer in this order. This compd. is incorporated into the charge transfer layer in case of the former and the compd. is incorporated into the charge generating layer or both of the charge generating layer and the charge transfer layer in case of the latter. The high-quality image having always the stable quality is formed in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor that has a photosensitive layer with excellent durability and exhibits little image quality deterioration due to repeated use. .

[Prior Art 7] In recent years, many electrophotographic photoreceptors using organic compounds as photoconductors have been developed. Of these, most of the ones that have been put into 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 said to have the advantage of high productivity due to the good film formation properties of the photosensitive layer, and are also flexible in material design, resulting in improved sensitivity and photoreceptivity. Even better electrophotographic properties such as responsiveness are expected.

By the way, since the electrophotographic photoreceptor is repeatedly subjected to various image forming processes by being used in an electrophotographic apparatus, the photoreceptor is required to maintain stable characteristics. However, electrophotographic photoreceptors using organic photoconductors have the disadvantage that, when used repeatedly, image quality deterioration such as image density decreases due to a decrease in charging ability and image blurring due to a decrease in surface resistance occurs. There is.

The influence of corona discharge is considered to be one of the causes of image deterioration. That is, when a photoreceptor is used in a copying machine, it is constantly exposed to an atmosphere of corona discharge, and as copies are repeatedly made, the organic photoconductor deteriorates due to active species such as ozone generated by corona discharge. Conceivable. 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, as a method of preventing the above-mentioned deterioration of electrophotographic photoreceptors, it has been proposed to add various oxidation inhibitors (Japanese Unexamined Patent Publications No. 57-122444 and No. 58-1202).
60, Japanese Patent Publication No. 61-156131. JP-A-62-105
151).

[Problems to be Solved by the Invention] Is the above-mentioned antioxidant capable of preventing image quality deterioration to some extent, or in practical terms, is the antioxidant even more effective? A drug is desired.

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

The present invention will be explained in detail below.

In the present invention, the photosensitive layer containing an organic photoconductor is a single-layer type containing a mixture of a charge-generating material and a charge-transporting material separated in function, a charge-generating layer containing a charge-generating material and a charge-transporting material. It takes the form of a laminate type in which a charge transport layer containing a 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, aso pigments, indigo pigments, and quinacridone pigments are used.

As charge transport materials, pyrazoline type, hydrazone type,
Stilbene series, triphenylamine series, benzidine series,
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 dispersed and dissolved in a suitable binder resin, and this is applied onto a conductive substrate to form a photosensitive layer.

In addition, as a laminated photoreceptor, (1) a charge generation layer and a charge transport layer are laminated in this order on a conductive substrate, or (2)
) A charge transport layer and a charge generation layer are laminated in this order.

In the case of (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 same, as well as a method of vapor deposition and sputtering. The charge transport layer is formed by dispersing and dissolving a charge transport material and a binder resin in a solvent and laminating it on the charge generation layer. In this case, the structural formula (
It is preferable to include the compound represented by 1) in the charge transport layer.

In the case of (2), the charge transport material and binder resin are dispersed in a solvent, dissolved, and applied! 1 to form a charge transport layer, and then a charge generation material and a binder resin are dispersed and dissolved in a solvent and coated on the layer to form a charge generation layer. At this time, it is preferable that a charge transport material is also contained in the charge generation layer. In this case, it is preferable that the compound of structural formula (1) be contained in the charge generation layer or both the charge generation layer and the charge transport layer.

The content of the compound of structural formula (1) is determined by the amount of the compound represented by structural formula (1) in the photosensitive layer (a
charge generation layer and/or charge transport layer if desired)
It is preferably in the range of 0.1 to 10% by weight, more preferably in the range of 0.3 to 5% by weight, based on the total weight. If the content is less than 0.1% by weight, the effect of preventing deterioration tends to be reduced, and if it exceeds 10% by weight, it tends to have adverse effects such as a decrease in sensitivity and an increase in residual potential.

The compound of structural formula (1) has a very high antioxidant function even when used alone, and it protects against Ol and NO generated by corona discharge.
It is also effective to use a sulfur-based or phosphorus-based secondary antioxidant that can prevent deterioration of the photosensitive layer due to x. Furthermore, the photosensitive layer of the present invention may contain known additives such as lubricants to reduce abrasion, surface modifiers, and plasticizers to improve flexibility.

Examples of the conductive substrate include known ones, such as cylindrical or belt-shaped aluminum, iron, copper, or metal-deposited plastic films. Furthermore, an intermediate layer such as an adhesive layer, a barrier layer, and a smooth layer may be provided between the substrate and the photosensitive layer, if necessary.

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

Example 1 An aluminum cylinder with a diameter of 80 mm and a length of 360 mm was used as a conductive substrate, and a 5% methanol solution of polyamide resin (trade name: Amilan CM-8000, manufactured by Toshi) was applied to this by dipping. A subbing layer with a thickness of 0.57411 was formed.

Next, 10 parts (parts by weight,
The same applies below) Part, Polycarbonate polyvinyl butyral resin (Product name: S-LEC BL-
5. 6 parts of hydrated water and 50 parts of cyclohexanone were dispersed in a sand mill using 1φ glass beads. 100 parts of methyl ethyl ketone was added to this dispersion and applied onto the undercoat layer.

A charge generation layer having a thickness of 0.28 parts w was formed.

Next, 10 parts of a stilbene compound having the following structural formula (trade name: Panlite L-1250, manufactured by Kijin Kasei) was dissolved in 50 parts of dichloromethane and 10 parts of monochlorobenzene to prepare a charge transport layer coating solution. To this coating liquid, further added 0.04 parts, 0.3 parts of the compound of the structural formula (1),
A photoreceptor was prepared by coating the above charge generation layer with 0.6 parts, 1.8 parts, and 3 parts, respectively, to form a charge transport layer having a thickness of L8 pm. The photoreceptors thus produced are referred to as photoreceptors 1, 2, 3, and 4.5, respectively.

For comparison, photoreceptor 6 was prepared without adding the compound of structural formula (1). Further, for comparison, photoreceptors to which 0.3 parts of compounds represented by the following structural formulas (8) and (B) were added instead of the compound represented by structural formula (1) were designated as photoreceptors 7 and 8, respectively.

The potential after continuous copying of 500 sheets was measured, and the rate of decrease in vo and the increase in vL were determined. Thereafter, after leaving the photoreceptor with the marked part directly under the corona charger in the copying machine for 10 hours, the surface potential of the marked part and other parts was measured, and the difference (Δv0) (hereinafter referred to as (also called hibernation memory). The results are shown in Table 1.

These photoreceptors were installed in an electrophotographic copying machine, and their characteristics were evaluated as follows. First, the dark area charge (vn
) and bright area potential (Vt, ) are -650v and -1, respectively.
The latent image conditions were set so that the voltage was 50V. The image exposure amount at that time was determined, and the initial impression was obtained.The added amount shown in the table is the ratio to the weight of the photosensitive layer to which the additive was added, that is, the charge transport layer here.

As is clear from Table 1, for the photoreceptor that does not contain the compound of structural formula (1), the absolute value of the dark area potential J51 is significantly reduced by undergoing the edge-reversing electrophotographic process.
The absolute value of the dark potential after standing was also significantly reduced. In addition, for photoreceptors containing structural formulas (A) and (B),
Although the dark area potential and the dark area potential after standing were improved to some extent, it was not sufficient, and an increase in the bright area potential was observed. On the other hand, the content of the compound of structural formula (1) is 1.5,
The photoreceptors of 3.0 and 9.0 were excellent with little decrease in charging ability, and no other practical adverse effects were observed.

Further, when the amount added was 15.0% by weight, the absolute value of the bright area potential increased.

Example 2 In the same manner as in Example 1, an undercoat layer was formed on an aluminum cylinder. Next, 15 parts of the stilbene compound used as the charge transport material in Example 1 and 10 parts of bisphenol Z type polycarbonate resin were mixed with 50 parts of dichloromethane,
A solution dissolved in 10 parts of monochlorobenzene was applied onto the undercoat layer to form a charge transport layer with a thickness of 15 ga.

Next, 4 parts of the same trisazo pigment used in Example 1,
10 parts of bisphenol Z type polycarbonate resin and 50 parts of cyclohexanone were dispersed for 20 hours using a sand mill device using 1φ glass beads (CG dispersion ■).
.

Next, polytetrafluoroethylene resin powder, a fluorine-based acrylic oligomer as a dispersant, the above-mentioned stilbene compound, and bisphenol z5 polycarbonate resin were prepared. First, 10 parts of bisphenol Z type polycarbonate resin, 4 parts of stilbene compound, and 0.15 parts of fluorine-based acrylic oligomer are dissolved in 10 parts of dichloromethane and 40 parts of monochlorobenzene.

Polytetrafluoroethylene resin powder 1 is added to the solution thus obtained.
．． 5 parts, 0.5 part of the compound of the above structural formula (1), and 0.5 part of the sulfur-based secondary antioxidant of the following structural formula (2),
C1l□C with stainless steel ball mill! 1. cOOc, +11° for 40 hours (CT dispersion ■).

A photoreceptor was manufactured by coating a mixture of CG dispersion (1) and CT dispersion (2) at a ratio of 1:1 on the charge transport layer to form a charge generation layer with a thickness of 5 ILm.

This photoreceptor was evaluated in the same manner as in Example 1 using the copying machine used in Example 1 modified to allow positive charging, and it was found that even after a durability test of 100,000 copies, there were no fluctuations in bright area potential or dark area potential. , the pause memory was small, and high-quality copies were obtained.

Example 3 An undercoat layer was formed on an aluminum cylinder in the same manner as in Example 1. Next, 1 part of a disazo pigment having the following structural formula, and 10 parts of the stilbene compound used in Example 1.

A coating solution prepared by dispersing and dissolving 10 parts of bisphenol Z type polycarbonate resin, 0.3 parts of the compound of structural formula (1), and 0.5 parts of the compound of structural formula (2) in 60 parts of dichloromethane and 20 parts of monochlorobenzene was prepared as above. A photoreceptor was prepared by coating the undercoat layer to form a photosensitive layer having a thickness of 16 g.

When this photoreceptor was evaluated in the same manner as in Example 1 using the modified copying machine used in Example 2, it was found that even after a 100,000-sheet durability test, the rest memory of bright area potential and dark area potential fluctuation was small, and high-quality copies were obtained. was gotten.

[Effect of the invention] The electrophotographic photoreceptor of the present invention is subjected to a corona discharge environment.

The stability of bright area potential, dark area potential, and potential stability such as pause memory is extremely high, and stable, high-quality images can be formed at all times. Further, the electrophotographic photoreceptor of the present invention can be used as a photoreceptor for printers that apply electrophotography, such as ordinary copying machines, laser beam printers, LED printers, LCD printers, and CRT printers.

Agent Patent Attorney Sekihei Yamashita

Claims (1)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive substrate, the photosensitive layer containing a compound represented by the following structural formula (1). An electrophotographic photoreceptor characterized by: ▲Mathematical formulas, chemical formulas, tables, etc.▼(1) 2. The electron according to claim 1, wherein the photosensitive layer is a stack of a charge generation layer and a charge transport layer. Photographic photoreceptor. 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. The electrophotographic photoreceptor according to claim 1, wherein the content of the compound represented by structural formula (1) is 0.1 to 10% by weight based on the weight of the photosensitive layer.