JPH0582938B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an electrophotographic photoreceptor. More specifically, the present invention relates to an electrophotographic photoreceptor containing a novel compound as a charge transport substance in a photosensitive layer on a conductive support. [Prior Art] Conventionally, inorganic photosensitive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used as photosensitive materials for electrophotographic photoreceptors. However, photoreceptors using these photosensitive materials do not fully satisfy the performance requirements for electrophotographic photoreceptors, such as sensitivity, photostability, moisture resistance, and durability. For example, a photoreceptor using a selenium-based material has excellent sensitivity, but the characteristics of the photoreceptor tend to deteriorate due to crystallization due to heat or adhesion of dirt. Also,
Since it is manufactured by vacuum deposition, it is expensive, and it also has many drawbacks, such as being difficult to process into a belt because it is not flexible. Photoreceptors using cadmium sulfide-based materials have problems with moisture resistance and durability, and photoreceptors using zinc oxide have problems with durability. In order to overcome the drawbacks of photoreceptors using these inorganic photosensitive materials, various studies have been made on photoreceptors using organic photosensitive materials. In recent years, among photoreceptors developed to improve the above-mentioned drawbacks, a functionally separated photoreceptor in which charge generation function and charge transport function are shared by separate substances has been attracting attention. In this functionally separated photoreceptor, materials having respective functions can be selected from a wide range of materials and combined, so it is possible to create a photoreceptor with high sensitivity and high durability. The characteristics required of the charge transport material contained in an electrophotographic photoreceptor are (1) a sufficiently high ability to accept the charge generated by the charge generation material, (2) the ability to rapidly transport the received charge, (3) Sufficient charge transport should be carried out even in low electrolysis conditions, and no charge should remain. Furthermore, the photoreceptor is required to be stable against light, heat, etc. received during the repeated steps of charging, exposure, and transfer during copying, and to be durable enough to produce copied images with good reproducibility that are faithful to the original image. Various compounds have been proposed as charge transport materials. For example, poly-N-vinylcaribazole has long been known as a photoconductive material.
Products using this material as a charge transport material have been put to practical use, but they themselves lack flexibility, are brittle, and are prone to cracking, resulting in poor durability against repeated use. Furthermore, when it is used in combination with a binder to improve flexibility, it has the disadvantage of poor electrophotographic properties. On the other hand, since low molecular weight compounds generally do not have film properties, they are usually mixed with a binder in an arbitrary composition to form a photosensitive layer. Many charge transport materials have been proposed as low molecular weight compounds. For example, hydrazone compounds have high sensitivity as charge transport materials;
No. 52064, JP-A-57-58156, JP-A-58-58157
It is stated in the official gazette such as No. However, there are problems with decomposition due to ozone generated during corona charging, and stability against light and heat.Although the initial performance is excellent, repeated use causes a decrease in charge retention ability or accumulation of residual potential.
The resulting image had reduced contrast or had a lot of fog. Although many other charge transport materials have been proposed, the current situation is that none of them practically satisfies the required performance as an electrophotographic photoreceptor, and the development of an even better photoreceptor has been desired. [Means for Solving the Problems] The present inventors have made extensive studies to solve the above problems, and as a result, the general formula ()

[Formula, Y is a hydrogen atom, an alkyl group, an alkoxy group, or

[Formula], R ₁ and R ₂ are optionally substituted alkyl groups, aralkyl groups, or aryl groups, and R ₁ and R ₂ may be bonded together to form a ring with the nitrogen atom. X is an oxygen atom or a sulfur atom. n is an integer of 0 or 1. The present inventors have discovered that a compound represented by the following formula can provide an electrophotographic photoreceptor having excellent properties such as high sensitivity and high durability, and have arrived at the present invention. Although the relationship between the molecular structure of charge transport materials and photoconductive performance has not yet been fully elucidated, the compound of the present invention has the following structure.

It is characterized by having the following formula: (wherein, It can be assumed that That is, the present invention provides a photosensitive layer on a conductive support having the general formula ()

[Formula, Y is a hydrogen atom, an alkyl group, an alkoxy group, or

[Formula], R ₁ and R ₂ represent an optionally substituted alkyl group, aralkyl group, or aryl group, and R ₁ and R ₂ may be bonded together to form a nitrogen atom. X represents an oxygen atom or a sulfur atom. n is an integer of 0 or 1. ) This is an electrophotographic photoreceptor characterized by containing a compound represented by the following. In Y of the general formula (), examples of the alkyl group include a methyl group, ethyl group, and propyl group; examples of the alkoxy group include a methoxy group and an ethoxy group; and as R ₁ and R ₂ ,
Examples include alkyl groups such as methyl group and ethyl group, aralkyl groups such as benzyl group and phenethyl group, and aryl groups such as phenyl group and naphthyl group. Examples of the group in which R ₁ and R ₂ combine to form a ring together with a nitrogen atom include a pyrrolidino group and a piperidino group. As Y

A substituted amino group represented by the formula is preferred because it exhibits high sensitivity. More specific compounds that can be used in the present invention are shown in Table 1, but the compounds that can be used in the present invention are not limited to these. The compound represented by the above general formula () can be synthesized by a conventional method. For example, general formula ()

[Formula] (In the formula, X is the same as the general formula (). Q is -
P ⁺ (—R ₃ ) ₃・Z ^- or −PO (OR ₄ ) ₂ . Here R ₃ is a phenyl group or a lower alkyl group,
Z ^- is a halogen ion or BF ₄ ^- , and R ₄ is a lower alkyl group. ) In the presence of a base, a phosphorus derivative represented by the general formula ()

It can be obtained by reacting an aldehyde compound represented by the formula: (wherein Y and n are the same as in the general formula ()).

[Action and effect]

The electrophotographic photoreceptor of the present invention has high sensitivity and excellent performance that does not deteriorate with repeated use by using the compound represented by the general formula () as a charge transport material. [Example] The present invention will be specifically described below with reference to Examples, but the embodiments of the present invention are not limited thereto. Production Example 1 Synthesis of Exemplified Compound No. 4 Represented by the following structural formula in 50 ml of tetrahydrofuran

[Formula] Suspend 2.2g of the compound, n-butyllithium
Add 4 ml of 1.5N hexane solution dropwise at -78°C,
Stirred for 1 hour. p-dimethylaminocinnamaldehyde 0.9g
A solution prepared by dissolving . 200 ml of saturated aqueous ammonium chloride solution was added, and the mixture was extracted with 200 ml of chloroform, washed with water, dried over magnesium sulfate, and concentrated. The residue was recrystallized from benzene/n-hexane to obtain orange crystals. (Melting point: 127-129°C) The obtained compound was designated as Exemplified Compound No. by elemental analysis.
It was confirmed that it was 4. Elemental analysis value (%) Actual value C 84.87 H 6.22 N 4.08 Calculated value C 84.96 H 6.17 N 4.13 Production example 2 Synthesis of exemplified compound No. 10 3.1 g of compound represented by the following structural formula

To 100 ml of a tetrahydrofuran solution of [Formula], 8 ml of a 1.5N hexane solution of n-butyllithium was added dropwise at -78°C, and the mixture was stirred for 30 minutes. p-tolualdehyde at the same temperature
After 1.2 g was added dropwise and stirred for 20 minutes, the temperature was raised to room temperature and further stirred for 2 hours. After adding 1 ml of methanol and concentrating under reduced pressure, 100 ml of water was added and extracted with 100 ml of chloroform. After dehydration over anhydrous magnesium sulfate, it was concentrated under reduced pressure, and the residue was recrystallized from methanol to obtain yellow crystals. (Melting point 128-129℃) The obtained compound was found to be an exemplified compound based on the elemental analysis value.
I confirmed that it was No.10. Elemental analysis value (%) Actual value C 83.92 H 5.30 S 10.70 Calculated value C 84.00 H 5.33 S 10.67 Example 1 0.5 g of polyester resin (manufactured by Toyobo, trade name "Vylon 200"), disazo dye represented by the following structural formula 0.5g

[ka] (However, A in the formula is

[Chemical formula] and Ph is a phenyl group. ) and 50 g of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied using a wire bar onto a conductive support made of a polyester film laminated with aluminum foil, and dried at 80°C for 20 minutes to form a powder of about 0.5 μm. A charge generation layer was formed. On this charge generation layer, exemplified compound No. 41g, polyester resin (trade name "Vylon 200" manufactured by Toyobo)
A solution of 1 g dissolved in 10 g of chloroform was applied using a wire bar, dried at 80°C for 30 minutes, and the thickness was approx.
A charge transport layer having a thickness of 18 μm was formed to produce a laminated photoreceptor shown in FIG. Using an electrostatic copying paper tester (Model EPA-8100 manufactured by Kawaguchi Electric Seisakusho Co., Ltd.), the voltage applied to the photoreceptor was
Charge it with a 6KV corona discharge, measure the surface potential V ₀ at that time, leave it in a dark place for 2 seconds, measure the surface potential V ₂ at that time, and then apply a halogen lamp with the surface illuminance of the photoreceptor at 51ux. (color temperature
2856〓) and the surface potential becomes 1/2 of V ₂ .
Measure the time to
sec) was calculated. Also, the surface potential after 10 seconds of light irradiation
V ₁₂ or residual potential was measured. Furthermore, the charging exposure operation was repeated 1000 times. Example 2 Disazo dye represented by the following structural formula

[ka] (However, B in the formula is

[Formula] is. ) was used as the charge generating substance, a photoreceptor was prepared in the same manner as in Example 1, and the same measurements were carried out. Example 3 A photoreceptor was produced in the same manner as in Example 1 except that τ-type phthalocyanine was used as the charge generating substance,
Similar measurements were made. The measurement results of Examples 1 to 3 are shown in Table-2.

[Table] Example 4 The photoreceptor produced in Example 1 was attached to a commercially available electrophotographic copying machine to make copies, and even on the 10,000th copy, clear images without fogging that were faithful to the original were obtained. Examples 5 to 10 Exemplary compounds No. 1, 2, 6, and
Photoreceptors were prepared in the same manner as in Example 1 using Samples No. 9 and No. 10, respectively, and the same measurements were performed, and good performance was obtained. As described above, it can be said that the electrophotographic photoreceptor using the compound of the present invention has high sensitivity and stable performance even after repeated use, and is also excellent in durability.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing an example of the structure of an electrophotographic photoreceptor. In FIGS. 1 and 2, the respective symbols are as follows. 1... Conductive support, 2... Charge generating substance,
3...Charge transport material, 4,4'...Photosensitive layer, 5...
...Charge transport layer, 6...Charge generation layer.

Claims (1)

[Claims] 1 A photosensitive layer on a conductive support is formed by the general formula () [Chemical formula] (wherein, Y is a hydrogen atom, an alkyl group, an alkoxy _{group or} It is an optionally substituted alkyl group, aralkyl group, or aryl group, and R ₁ and R ₂ may be combined to form a ring with a nitrogen atom. X is an oxygen atom or a sulfur atom. n is 0 or an integer of 1.) An electrophotographic photoreceptor comprising a compound represented by: