JPH03138654A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic sensitive body having a high sensitivity and the excellent stability to repetitive use by incorporating a charge generating material and a charge transfer material into a photosensitive layer and incorporating specific compds. as the charge transfer material therein. CONSTITUTION:This photosensitive body has a conductive layer and the photo sensitive layer and contains the charge generating material and the charge transfer material in this photosensitive layer. At least one kind of the compds. expressed by formula I are incorporated as the charge transfer material into this layer. In the formula I, R<1>, R<2> denote a group selected from an alkyl group which may have a substituent, alkyl group which may have a substituent, etc.; R<1> and R<2> may form a ring; X denotes a hydrogen atom, etc. The electrophotographic sensitive body having the high sensitivity and the excellent stability to the repetitive use is obtd. in this way.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to an electrophotographic photoreceptor.

[Prior Art] Selenium, cadmium sulfide, zinc oxide, etc. have long been known as photoconductors used in electrophotographic processes. In recent years, organic photoconductors have come into use, which have advantages such as low toxicity and good transparency.

The basic characteristics required of an electrophotographic photoreceptor include good charge acceptance and charge retention in the dark, high sensitivity, low residual potential, and spectral sensitivity appropriate to the intended use. , excellent durability, and good workability. However, among the conventionally proposed organic photoconductors, there are hardly any that satisfy all of these required characteristics using a single material.

Therefore, a functionally separated photoreceptor is currently used as a bundle, which has a photosensitive layer on a conductive substrate that combines a charge-generating material that absorbs light and generates a charge, and a charge-transfer material that moves the generated charge. ing. This is aimed at improving the characteristics and widening the range of material selection by assigning the two functions of the photoreceptor to different materials.

In functionally separated photoreceptors, charge-generating substances are mainly organic dyes such as bisazo compounds, squarylium dyes, and phthalocyanines, and charge-transfer substances are mainly low-molecular-weight compounds with hole-transfer functions such as hydrazone compounds and pyrazoline derivatives. It is often used. Typical examples include the photoreceptor described in JP-A No. 54-59143;
A photoreceptor described in Japanese Patent No. 1.05537 is known.

[Problems to be Solved by the Invention] However, conventional functionally separated photoreceptors have problems such as insufficient sensitivity and significant deterioration of characteristics due to repeated use. In view of these circumstances, the inventors of the present invention conducted extensive research, and as a result, discovered that a photoreceptor containing a specific new charge transfer substance exhibits excellent characteristics, and arrived at the present invention.

An object of the present invention is to provide an electrophotographic photoreceptor with high sensitivity and excellent stability against repeated use.

[Means for Solving the Problems] The electrophotographic photoreceptor of the present invention includes a conductive layer and a photosensitive ml,
The electrophotographic photoreceptor is characterized in that the photosensitive layer contains a charge-generating substance and a charge-transfer substance, and contains at least one compound represented by the general formula (I) as the charge-transfer substance.

(In the formula, R1 and R2 represent groups selected from an alkyl group that may have a substituent, an aralkyl group that may have a substituent, and an aryl group that may have a substituent.)
may form a ring. X represents a hydrogen atom or a group represented by the following formula.

The compound represented by the general formula (I) is represented by the following general formula (II)
It can be easily synthesized by condensing an aldehyde represented by the formula (m) with a hydrazine derivative represented by the general formula (m) or a salt thereof.

(In the formula, Y represents a hydrogen atom or a formyl group.

) (In the formula, R1 and R2 represent the same group as in general formula (I).

) The substituents R1 and R2 in general formula (I) are preferably substituents as described below.

When the substituent R1 or R2 is an alkyl group, it preferably has 1 to 20 carbon atoms, and may be linear or branched. When this further has a substituent, preferable substituents include a halogen atom, an alkoxy group, an aryloxy group, and a disubstituted amino group. When the substituent R1 or R2 is an aralkyl group, the aralkyl group represents an alkyl group substituted with one or more aryl groups, and preferably has 7 to 20 carbon atoms.

When this further has a substituent, preferred substituents include a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, and a di-substituted amino group. When substituent R1 or R2 is an aryl group, it preferably has 6 to 16 carbon atoms. In addition, when this further has a substituent, preferable substituents include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group,
Examples include disubstituted amine groups and divalent groups such as methylenedioxy groups. Further, when R1 and R2 form a ring, the ring consisting of R1, R2 and a nitrogen atom is a carbazole ring, 1. 2. 3. It is preferably a 4-tetrahydroquinoline ring, an indoline ring, a phenothiazine ring, a phenoxazine ring, or the like.

Specific examples of the charge transfer substance represented by the general formula (I) are shown on the following pages. However, the present invention is not limited to these.

The electrophotographic photoreceptor of the present invention has a conductive layer and a photosensitive layer, and the photosensitive layer contains a charge generating substance and a charge transporting substance. The photosensitive layer referred to herein may be a single layer type containing a charge generation substance and a charge transfer substance in a single layer, each layer having a different composition containing at least one of a charge generation substance and a charge transfer substance. It may be of a laminated type in which a plurality of layers are laminated to contain a charge generating substance and a charge transporting substance as a whole. Therefore, the photoreceptor may have the following configurations, for example.

(1) Conductive layer/layer containing charge-generating substance/layer containing charge-transfer substance (2) Conductive layer/layer containing charge-transfer substance/layer containing charge-generating substance (3) Conductive layer/layer containing charge-generating substance Layer Containing Substance and Charge Transfer Substance Since the charge transfer substance of the present invention is a hole transfer type, when used in a Carlson type electrophotographic process, the structure (1) is used.
The photoreceptor in ) is negatively charged; the photoreceptor in (2) is positively charged;
The photoreceptor of configuration (3) is used both positively and negatively charged.

The photoreceptors with each of the above configurations have an appropriate intermediate layer between the eyebrows to improve adhesion and control charge injection, and a protective layer or a protective layer on the surface.
An insulating layer, a white layer, etc. can be provided, and the concentration of components in each layer can be changed in the thickness direction.

Although the structure of the photoreceptor of the present invention can be modified in various ways other than the above-mentioned basic structure, the most common one is structure (1). Configuration (1) will be explained in detail below.

Any known conductive layer can be used as the conductive layer in configuration (1). For example, a metal material processed into a predetermined shape is used. Examples of metal materials in this case include aluminum, stainless steel, copper, nickel, and the like. Furthermore, a thin film of a conductive material formed on a suitable support may also be used. In this case, examples of the support include glass, resin, paper, cloth, etc., and examples of the conductive substance include metals such as aluminum, palladium, rhodium, gold, and platinum, carbon, or tin oxide and oxide. Examples of formation methods include conductive compounds such as indium tin, polymer electrolytes, and conductive polymers.
Examples of methods include vapor deposition, sputtering, coating, and lamination. The shape of the conductive layer can be freely selected from flat plates, drums, films, endless belts, etc. depending on the purpose of use.

The layer containing the charge generating substance of configuration (1), that is, the charge generating layer, contains the charge generating substance as an essential component. As the charge generating substance used here, any known charge generating substance can be used. Examples include, but are not limited to, the following:

(a) Azo pigment (b) Perylene pigment (C) Phthalocyanine derivative (d) Squarylium dye (e) Pyrylium and thiopyrylium derivatives (f) Aromatic polycyclic bovine compound (g) Pyrrolopyrrole derivative Spectral sensitivity characteristics of photoreceptor Since this is mainly determined by the charge-generating material, a charge-generating material with spectral sensitivity characteristics suitable for the process used is selected.

It is also possible to use a mixture of a plurality of charge generating substances in order to optimize the spectral sensitivity.

The charge generation layer can be formed by applying a paint in which a charge generation substance is dispersed in a solvent, a paint in which a charge generation substance and a suitable binding resin are dispersed in a solvent, or by vapor deposition of a charge generation substance. formed by. If the coating amount or adhesion amount of the charge generation layer is too large, the chargeability and repetition stability will be lowered, and if it is too small, the sensitivity will be lowered.

The preferred coating amount or adhesion amount of the charge generation layer is 0.01 to 0.01.
It is 1g/cm2.

When the charge generation layer is composed of a charge generation substance and a binding resin, a known binding resin can be used. Preferably used binding resins include the following.

Polyamide, polyester, polyurethane, polyimide, polycarbonate, polyarylate, polyacetal, polyethylene oxide, polypropylene oxide, polymethacrylate, polyacrylate, polystyrene, polyvinyl acetate, polyvinyl chloride, alkyd resin, butyral resin, silicone resin, Examples include, but are not limited to, epoxy resins and urea resins. These binding resins may be used alone or in a mixed system of two or more types, or may be a copolymer.

Further, crosslinking may be carried out by adding a suitable crosslinking agent.

When using a binding resin, the weight ratio of the charge generating substance to the binding resin is 110 from the viewpoint of film strength, adhesion and sensitivity.
．． It is preferable to set it to 2 to 1/2.

The layer containing a charge transfer substance in configuration (1), that is, the charge transfer layer, contains at least one compound represented by the general formula (I) as a charge transfer substance, but is represented by the formula (I). The charge transfer substance may be used alone or in combination of two or more types, or may be used together with other known charge transfer substances.

The charge transfer layer is formed by dissolving or dispersing the charge transfer substance and a suitable binding resin in a suitable solvent and applying a coating material on the charge generation layer. Preferably used binding resins include the same resins as exemplified in the section of the charge generation station. A preferable weight ratio of the charge transfer substance and the binding resin in the charge transfer layer is 110.2 from the viewpoint of sensitivity, response speed, and film strength.
It is best to set it to ~1/2. If the thickness of the charge transfer layer is too thin, the charging ability of the photoreceptor will decrease, and if it is too thick, the response speed will decrease and the residual potential will increase.

The preferred thickness of the charge transport layer is 5 to 3011 m,
More preferably, it is 10 to 25 μm.

Further, an antioxidant, an ultraviolet absorber, and the like can be added to this charge transfer layer in order to improve durability, repetition stability, and the like.

Next, photoreceptor configurations other than configuration (1) will be described.

The conductive layer, the layer containing a charge transfer substance, and the layer containing a charge generation substance in configuration (2) are the same as the corresponding layers in configuration (1,), except that the stacking order is different. It will be done.

The conductive layer in configuration (3) is the same as the conductive layer in configuration (1). The layer containing a charge transfer substance and a charge generation substance in configuration (3) is formed by applying a paint in which a charge transfer substance, a charge generation substance, and a binding resin are dispersed in a solvent onto the conductive layer. Ru. If the core layer is too thin, the charging ability of the photoreceptor will be reduced, and if it is too thick, the response speed will be reduced. The preferred thickness of the nuclear layer is 5
~30 μm. The charge transfer substance, charge generation substance, and binding resin used here are the same as those used in configuration (1). If the weight ratio of the charge-generating substance to the charge-transfer substance in the layer is too small, the sensitivity will be lowered, and if it is too large, the chargeability will be lowered and the stability against repetition will be lowered. The preferred weight ratio of the charge generating material and the charge transporting material in the layer is 1/2 to 1/1000.

Furthermore, if the weight ratio of the charge transfer substance to the binding resin in the layer is too small, the sensitivity and response speed will be reduced, and if it is too large, the film strength will be reduced.

The preferred weight ratio of the charge transfer substance and the binding resin in the layer is 110.2 to 1/2.

Between the photosensitive layer and the conductive layer mentioned above, there is a need to improve adhesion,
A suitable intermediate layer can be provided for controlling charge injection.

Further, a surface layer can be provided on the surface of the photosensitive layer for the purpose of improving durability.

[Examples] The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

Synthesis Example 1 In a mixed solvent of 500 m3 of ethanol and 50 cm3 of chloroform, an aldehyde represented by structural formula (II-1) 1.
8 g and 0.9 g of 1.1-diphenylhydrazine hydrochloride were added, and the mixture was stirred at room temperature for 50 minutes.

The reaction mixture was poured into water, extracted with chloroform, dried over magnesium sulfate, and concentrated to give 2.8 g of a yellow resin.
I got it. This was purified by column chromatography using silica gel to obtain exemplified compound (■-1) as yellow crystals.
Obtained as 5g. The melting point was 134°C.

Synthesis Example 2 In a mixed solvent of 50 cm3 of ethanol and 50 cm3 of chloroform, 1.3 g of an aldehyde represented by the structural formula (n-2) below and 1.5 g of 1,1-diphenylhydrazine hydrochloride were added.
g was added thereto, and the mixture was stirred at room temperature for 1 hour. The reaction mixture was poured into water, extracted with chloroform, dried over magnesium sulfate, and concentrated to give 2.7 g of a yellow resin. This was purified by column chromatography using silica gel to obtain Exemplified Compound (I-2) as 2.1 g of yellow crystals. The melting point was 149°C.

Example 1 Aluminum vapor deposited polyester film “Metal Me”
#75 (manufactured by Toshi Corporation) was used as a conductive layer, and on top of that, 10 parts of titanyl phthalocyanine and 10 parts of polyvinyl butyral resin "S-LEC" BL-1 (manufactured by Tanemizu Chemical Industry Ltd.) were added in cyclohexanone to a solid concentration of 2. A charge generation layer was formed by applying a coating material dispersed at 5% by weight using a wire bar at a coating amount of 0.15g/cm2. Next, 10 parts of exemplified charge transfer substance (I-1) and 1 part of polycarbonate resin "Panlite" L-1225 (manufactured by Kijin Kasei)
A paint prepared by dissolving 0 parts in 1,2-dichloroethane to a solid content concentration of 20% by weight was applied onto the charge generating layer using a wire bar to a thickness of 20 μm.
A charge transfer layer was formed.

The photoreceptor thus obtained was statically charged with a corona charge of 15 kY using an electrostatic copying paper tester EPA-8100 (manufactured by Kawaguchi Denki ■), held in a dark place for 5 seconds, and then The change in surface potential over time was measured under the condition of exposure at 1-μW/cm 2 for 5 seconds, and the half-reduction exposure amount El/□ was determined from the potential decay curve. The result was as follows.

El/2=0. 38μJ/cm2 Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1 except that the charge transfer substance was changed to a hydrazone compound shown by the following formula.The half-decreased exposure of this photoconductor was measured under the same conditions as in Example 1. , the results were as follows.

El/2=0. 69 μJ/Cm2 Examples 2-1
1 Example 1 except that the charge transfer substance was changed to those shown in the table.
Table 1 shows the results of measuring the half-decreased exposure amount of a photoreceptor prepared in the same manner as in Example 1 under the same conditions as in Example 1.

Table 1 Example No. Charge transfer substance Ei,'□[μJ
/cm2] 2 I-20,37 3I-30,38 4I-40,37 5I-50,38 6I-90,41 7l-100,40 8l-110,43 9l-120,41 10l-130,40 11l -140,39 Example 12 A photoreceptor drum was prepared by forming the same photoreceptor layer as the photoreceptor prepared in Example 1 on an aluminum drum by a dipping method. This was attached to a commercially available LED printer PC-PR601 (manufactured by NEC ■), and a printing test of 30,000 sheets was conducted.

The results of measuring the change in print density of the white background area and the black background area before and after the printing test using an image densitometer Macbeth TR927 are shown below.

Before printing test After printing test White area 0. 08 0. 08 Black area 1. 22 1. 20 Comparative Example 2 A photoreceptor drum was prepared by forming the same photoreceptor layer as the photoreceptor prepared in Comparative Example 1 on an aluminum drum by a dipping method. This was attached to the LED printer PC-PR601, and a printing test of 30,000 sheets was conducted. Changes in print density between white background and black background before and after the printing test using an image densitometer Macbeth T
The results measured with R927 are shown below.

Before printing test After printing test White area 0. 08 0. 10 Black area 1. 24 0. 98 Furthermore, many small black spots appeared on the white background of the print after 30,000 printing tests.

[Effects of the Invention] According to the present invention, an electrophotographic photoreceptor having high sensitivity and excellent stability against repeated use can be obtained.

Claims (1)

[Scope of Claims] A conductive layer and a photosensitive layer, the photosensitive layer containing a charge generating substance and a charge transfer substance, and at least one compound represented by the general formula (I) as the charge transfer substance. An electrophotographic photoreceptor characterized by containing. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^1 and R^2 are an alkyl group that may have a substituent, an aralkyl group that may have a substituent, and a Represents a group selected from aryl groups.R^1
and R^2 may form a ring. X represents a hydrogen atom or a group represented by the following formula. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼