JP3137723B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member containing an organic photoconductive substance.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic photoreceptor having a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate, the photoreceptor has the following structural formula (III) as a binder resin.
The polycarbonate resin which consists of a repeating unit shown by these is used.

[0003]

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[0004] The photosensitive layer is generally formed by dissolving and dispersing in an organic solvent such as tetrahydrofuran, methylene chloride, ethylene chloride, toluene, xylene, benzene, dioxane and the like, coating the conductive substrate and drying by heating.

In such a photoconductor, the developing layer or the cleaning section is rubbed by a developer or a cleaning member, and if used repeatedly for a long time, the photosensitive layer is scratched and the initial print quality is lost.

Accordingly, attention has been paid to a polycarbonate resin comprising a repeating unit represented by the formula (II) which is more excellent in mechanical properties such as abrasion resistance, tensile rupture strength and creep characteristics than a polycarbonate resin comprising a repeating unit represented by the formula (III). Have been.

[0007]

However, a polycarbonate resin comprising a repeating unit represented by the formula (II) has a gas permeability about half that of a polycarbonate resin comprising a repeating unit represented by the formula (III) (see Table 1). Therefore, when the photosensitive layer is dissolved and dispersed in an organic solvent under the same conditions, and coated on the conductive substrate by heating and drying, the amount of the residual solvent in the photosensitive layer increases (sometimes 10 times or more). ), The electrostatic properties such as residual potential and sensitivity are degraded.

For this reason, in order to increase the drying processing capacity, measures such as newly introducing drying equipment or increasing the processing time in the drying process have been taken. Will increase.

[0009]

[Table 1]

Notes 1. 1. L-1250 is a polycarbonate resin comprising a repeating unit represented by the formula (III). TS-2050 is a polycarbonate resin comprising a repeating unit represented by the formula (II). An object of the present invention is to improve the above-mentioned disadvantages by using a polycarbonate resin comprising a repeating unit represented by the formula (II). Under the same drying conditions as the polycarbonate resin composed of the repeating unit shown, the same as the polycarbonate resin composed of the repeating unit represented by the formula (III),
Another object of the present invention is to provide a highly reliable electrophotographic photoreceptor which does not cause deterioration of electrostatic characteristics such as residual potential and sensitivity with a residual solvent amount less than that, and can be manufactured at the same or lower production cost.

[0011]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that it is effective to include a specific benzophenone derivative in a specific amount in a photosensitive layer, and have reached the present invention.

Namely, the present invention provides an electrophotographic photosensitive member comprising successively a charge transport layer containing a charge-generating layer and a charge transporting substance and a binder resin containing a charge generating material on a conductive substrate, the charge The transport substance

Embedded image Wherein the charge transport layer is formed by adding a benzophenone derivative represented by the following structural formula (I) to 100 parts by weight of the binder resin.
An electrophotographic photoreceptor characterized by containing about 50 parts by weight.

[0013]

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Wherein R ₁ and R ₁ ′ represent a hydrogen atom, a hydroxyl group, a carboxyl group, a cyclohexyl group, an acetyl group, an aryl group, an aralkyl group or an alkyl group having 1 to 5 carbon atoms. . However, the charge transport material is
Hydrazone compound represented by the following formula, stilbene compound
Except when.

Embedded image The benzophenone derivative represented by the above formula (I) can be used in various ratios as long as the electrostatic characteristics are not deteriorated, and the benzophenone derivative is used in an amount of 2 to 50 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the binder resin. When 30 parts by weight is used, the balance between the electrostatic characteristics and the effect of reducing the residual solvent is good.

The benzophenone derivatives may be used alone or in combination of two or more. Examples of the benzophenone derivative represented by the general formula (I) include benzophenone, benzoylbenzoic acid, methylbenzophenone, dimethylbenzophenone, hydroxybenzophenone, dihydroxybenzophenone, methoxybenzophenone, dimethoxybenzophenone, and bis (dimethylamino) benzophenone. It is not limited to these compounds.

These benzophenone derivatives have the formula (II)
It is considered that the gas permeability is increased by penetrating between the molecules of the polycarbonate resin composed of the repeating unit represented by and widening the molecular spacing. Therefore, even under the same drying conditions, the amount of residual solvent is significantly reduced as compared with the photosensitive layer containing no benzophenone derivative.

In the present invention, it is important to incorporate a benzophenone derivative into the photosensitive layer as described above.
The charge generation material, charge transport material, conductive substrate, and the like are not particularly limited. As the binder resin, the above formula (I
Although a polycarbonate resin having (I) is particularly preferred, the present invention is not limited to this, and other binder resins can be used.

[0018]

The present invention will be described below in detail with reference to examples.

Example 1 A photosensitive layer was provided on a conductive substrate having a 500 μm thick Al layer formed on a 75 μm-thick polyethylene terephthalate film by a vacuum evaporation method as described below. Produced.

Trisazo pigment (compound 1) (manufactured by Ricoh) 15.0 g Butyral resin (XYHL: manufactured by UCC) 5.0 g Cyclohexanone (manufactured by Kanto Kagaku) 150 g of a mixture consisting of a glass pot and agate having a size of 10 mmφ After ball milling for 48 hours using a ball, 300 g of cyclohexanone was added and milling was further performed for 1 hour. Cyclohexanone was further added to the milling solution to prepare a charge generation layer coating solution having a solid content concentration of 2 wt%, and a charge generation layer having a thickness of 0.2 μm was provided.

Subsequently, a coating liquid for a charge transport layer having the following composition was nozzle-coated on the charge generation layer and dried at 130 ° C. for 6 minutes to form a charge transport layer having a thickness of 20 μm to form a photosensitive layer. .

Charge transport substance (compound 2) (manufactured by Ricoh) 9 g Polycarbonate resin [resin (1)] (TS2050: manufactured by Teijin Chemicals) 10 g Benzophenone (manufactured by Kanto Chemical) 2 g Toluene 90 g

[0023]

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[0024]

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[0025]

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Example 2 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that hydroxybenzophenone (manufactured by Kanto Chemical Co.) was used instead of benzophenone.

Comparative Example 1 In Example 1, the polycarbonate resin 1 was replaced with a bisphenol A type polycarbonate resin (C-1400 manufactured by Teijin Chemicals Ltd.) represented by the structural formula (III), and toluene was replaced with tetrahydrofuron. An electrophotographic photosensitive member for comparison was prepared in the same manner as in Example 1 except that benzophenone was not used.

Comparative Example 2 An electrophotographic photosensitive member for comparison was produced in the same manner as in Example 1 except that tetrahydrofuran was used instead of toluene and benzophenone was not used.

Comparative Example 3 In Comparative Example 2, the drying conditions were 130 ° C. for 6 minutes at 130 ° C.
An electrophotographic photoreceptor for comparison was produced in the same manner as in Comparative Example 2 except that the temperature was changed to 12 ° C. for 12 minutes.

Comparative Example 4 An electrophotographic photosensitive member for comparison was produced in the same manner as in Comparative Example 3 except that toluene was used instead of tetrahydrofuran.

Comparative Example 5 A comparative electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the amount of benzophenone added was 0.1 g.

The photoreceptor thus prepared was measured by a dynamic method using an electrostatic property measuring device SP-428 (manufactured by Kawaguchi Electric Works).

First, the photosensitive member is charged at an applied voltage of −6 kV for 20 seconds, then darkly attenuated for 20 seconds, and further charged with a tungsten lamp so that the illuminance on the surface of the photosensitive member becomes 4.5 lux.
Exposure was performed for 0 seconds. After exposure, the surface potential was-
Exposure amount E _1/10 required for changing from 800 V to −80 V (lu
x · sec), the residual potential V ₃₀ was evaluated by measuring the surface potential 30 seconds after exposure.

Further, a forced fatigue test (for a photoconductor of 1,000
While rotating at 0 rpm, the surface of the photoconductor becomes -800
V, the exposure by the corona charging and the tungsten lamp is continuously repeated so as to be 9.6 μA. ) And the residual potential were also measured. In addition, ozone exposure (5p
after 5 days in a pm atmosphere) and the residual potential were also measured. The residual solvent amount was calculated from the following calibration curve of the standard solution under the following conditions.

-Measurement conditions- Apparatus Shimadzu GC15A gas chromatograph Nihon Kagaku Kogyo Curie Point Pyrolyzer JHP-3S column 10% PEG20M / Chromosorb W AW 60-80 mesh glass 3mx3mmφ Column temperature 80 ° C Thermal decomposition temperature / heating (time) The results obtained at 358 ° C./3 sec are shown in Table 2 below.

[0036]

[Table 2]

On the other hand, the photoreceptor of Example 1 was used as an electrophotographic laser beam printer (RICOH LP2310).
-SP5) When mounted on a remodeled machine and subjected to an image output test, up to 150,000 sheets of clear images without image defects were obtained.

When the photosensitive members of Comparative Examples 1 and 2 were subjected to an image output test in the same manner,
Stain on the background became apparent from around 0 and 30,000 sheets.

[0039]

As described above, the electrophotographic photoreceptor formed with the photosensitive layer containing the benzophenone derivative of the present invention does not increase in residual potential even after repeated use over a long period of time, and is free from image defects. And a highly reliable, highly durable and highly reliable electrophotographic photoreceptor.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-166605 (JP, A) JP-A-2-97954 (JP, A) JP-A-2-298951 (JP, A) JP-A 64-64 63965 (JP, A) JP-A-57-132154 (JP, A) JP-A-58-163945 (JP, A) JP-A-5-142813 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) G03G 5/00-5/16

Claims (3)

(57) [Claims] 1. A conductive and the charge generation layer containing a charge generating substance on a substrate the charge transport material and an electrophotographic photosensitive member comprising successively a charge transport layer containing a binder resin, electric
Charge transport material is embedded image Wherein the charge transport layer is formed by adding a benzophenone derivative represented by the following structural formula (I) to 100 parts by weight of the binder resin.
An electrophotographic photoreceptor containing from about 50 to 50 parts by weight. Embedded image [However, in the above formula (I), R ₁ and R ₁ ′ represent a hydrogen atom, a hydroxyl group, a carboxyl group, a cyclohexyl group, an acetyl group, an aryl group, an aralkyl group or an alkyl group having 1 to 5 carbon atoms. ] 2. The photosensitive layer as a binder resin having the following structural formula (I)
2. The electrophotographic photoreceptor according to claim 1, comprising a polycarbonate resin comprising a repeating unit represented by I). Embedded image (Wherein, X and X ′ represent a hydrogen atom, a halogen atom or a methyl group, and R represents a hydrogen atom, a halogen atom, a hydroxyl group,
Represents a carboxyl group, an acetyl group, or an alkyl group having 1 to 5 carbon atoms. ) 3. A photosensitive layer-forming material comprising: toluene, xylene, benzene, tetrahydrofuran, dioxane, cyclohexanone, chlorobenzene, methyl ethyl ketone,
2. The method for producing an electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photosensitive member is dissolved and dispersed in an organic solvent containing at least one selected from methylene chloride and ethylene chloride, and applied and formed on the conductive substrate.