JPS6242162A - Lamination type photosensitive body - Google Patents

Abstract

PURPOSE:To stabilize electrophotographic characteristics including residual potential and sensitivity when a photosensitive body is repeatedly used by incorporating a specific disazo pigment into an electric charge generating layer and incorporating a specific arom. polycarboxylic acid into an electric charge transfer layer. CONSTITUTION:The charge transfer layer is formed on a conductive base by depositing the disazo pigment expressed by the formula [I] by evaporation on the base or coating a coating liquid prepd. by dissolving said pigment into a suitable solvent or, if necessary, by dispersing said pigment into a soln. dissolved with a binder resin on the base and drying the coating. The soln prepd. by dissolving the arom. polycarboxylic acid expressed by the formula [II] and binder and, if necessary, an electric charge transfer material into a suitable solvent is coated thereon and is dried to form the charge transfer layer, by which a lamination type photosensitive body is obtd. The amt. of the arom. polycarboxylic acid to be added varies with the kind thereof and the effect of the addition is higher with the slighter amt. as the number of the carboxyl group contained in the arom. polycarboxylic acid is larger. Said acid needs be added at the higher ratio as the number of the carboxyl group contained therein is smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a photoreceptor using a disazo pigment as a charge generating agent and an aromatic polycarboxylic acid as a photofatigue inhibitor.

PRIOR ART AND PROBLEMS Many functionally separated photoreceptors are known in which a charge generation layer and a charge transport layer are laminated on a conductive support. A functionally separated photoreceptor has a high surface potential, a large charge retention capacity, high photosensitivity, and has excellent repeatability and characteristics. A stable photosensitive layer can be obtained.

Many organic pigments such as azo pigments, indigo pigments, and phthalocyanine pigments are known for functionally separated charge generation phase separation and 17, but Japanese Patent Application Laid-Open Nos. 52-4241 and 52-55643 The disazo pigments described in the publication are particularly effective as charge-generating materials. On the other hand, as charge transport materials for charge transport, azine compounds,
Hydrazone compounds, pyrazoline compounds, oxadiazole compounds, and the like are known. However, laminated photoreceptors in which these charge-generating materials and charge-transporting materials are combined and laminated on a conductive support have high charging ability and little change in surface potential when used repeatedly, but they have the disadvantage of low sensitivity. have In this regard, it has been proposed to add an organic compound as a sensitizer to the charge generating material. For example, JP-A No. 55-46760 describes a photoreceptor to which an organic dye is added as a sensitizer. However, although these photoreceptors have high sensitivity, their electrophotographic properties deteriorate when used repeatedly. has the disadvantage of being unstable.

Means for Solving the Problems It is an object of the present invention to eliminate the above-mentioned conventional drawbacks and to provide a photoreceptor whose electrophotographic characteristics are stable even after repeated use.

The gist of the present invention is to provide a laminated photoreceptor comprising an electromotive generation layer and an electromotive transport layer laminated on a conductive support.
The charge generation layer contains a disazo pigment represented by the general formula F [I], and the charge transport layer contains a disazo pigment represented by the general formula F [11].
It is characterized by a laminated photoreceptor containing an aromatic polycarboxylic acid represented by:

General formula: [In the formula, R1 and R2 represent 10 gen. ] Preferred specific examples of the aromatic polycarboxylic acid represented by the general formula (ll) of the present invention include OOH and the like.

Specifically, a disazo pigment is deposited on a conductive support, or a coating solution prepared by dispersing it in an appropriate solvent or, if necessary, a solution containing a binder resin, is applied, dried, and charged. A transport layer is formed, and a solution of an aromatic polycarboxylic acid, a binder resin, and, if necessary, a charge transport material dissolved in a suitable solvent is applied and dried to form a charge transport layer. You get a body.

Aromatic polycarboxylic acids are effective as photofatigue inhibitors even when used alone, but when used in combination with charge transport materials, the more carboxyl groups the carboxylic acids contain, the more effective they are when added in small amounts; The smaller the number of groups, the more must be added. For example, pyromellitic anhydride preferably has a molar concentration of 0.01 to 0.04%, and phthalic acid has a molar concentration of 0.1 to 0.5%, based on the charge transport material used.
However, the total amount of aromatic polycarboxylic acid added is 0.01% to 0.5%. Addition amount is 0.5%
When the amount increases, the charge retention ability deteriorates, the dark decay rate increases, and the change in surface potential increases when repeatedly used.

On the other hand, the thickness of the charge generation layer is 4 μm or more F1, preferably 2 μm
m or more F, and the thickness of the charge transport layer is preferably 3 to 30 μm, preferably 5 to 20 μm.

Examples of charge transport materials used in the charge transport layer include azine compounds and oxadiazole compounds, and preferably hydrazone compounds, especially F, which effectively prevent tramping of charge carriers injected from the charge generation layer. Hydrazone compounds represented by the following general formulas (III) and (IT) are preferred.

General formula: [wherein, X and Y are each independently (-, hydrogen, lower alkyl group, methoxy group, or ethoxy group; group, Z' represents hydrogen, an alkyl group or an alkoxy group, and 艮 represents a lower alkyl group, an aryl group which may have a substituent, or a benzyl group.] [In the formula, 艮 represents a methyl group, an ethyl group, represents a benzyl group or a phenyl group, and Z represents a methyl group, an ethyl group, an i-hydroxyethyl group, or a chloroethyl group t0] In addition, by using these charge transport materials together, , preferably 0.01 to 0.5% on a molar warm basis.

As binders, all electrically insulating thermoplastic resins, thermosetting resins, photocurable resins, and photoconductive resins that are known per se can be used. Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers,
Thermoplastic binders such as ionically crosslinked olefin copolymers (iono-7-), styrene-butadiene block copolymers, polyarylates, polycarbonates, vinyl chloride-vinyl acetate copolymers, cellulose esters, polyimides, styrene resins, etc. ; Thermosetting binders such as epoxy resins, urethane resins, silicone resins, phenol resins, melamine resins, xylene resins, alkyd resins, thermosetting acrylic resins; Photocurable resins; Poly-N-vinylcarbazole, polyvinylpyrene , photoconductive resins such as polyvinyl anthracene, etc. These can be used alone or in combination. It is desirable that these electrically insulating resins have a volume resistivity of 1X10''Ω.multidot. or more when measured alone. More preferred are polyester resin, polycarbonate, and acrylic resin.

Effects of the Invention The laminated photoreceptor of the present invention contains a disazo pigment in the charge generation layer and an aromatic polycarboxylic acid in the charge transport layer, so that when it is repeatedly used, residual potential and electronic sensitivity including sensitivity are reduced. The photographic characteristics are stable.

Example 1 1 part of a disazo compound represented by the chemical formula (A'),
After dispersing 1 part of polyester resin (Toyobo V-200) and 90 m of clohexanone using a sand glider, the weight per unit area after drying on aluminum foil was 0.2.9/lo' It was coated with a wire bar so that the charge generation layer was formed and dried to form a charge generation layer.

General formula: 10 parts of a hydrazone compound represented by the chemical formula F [: B-1, chemical formula CB-2)]
1 part of the hydrazone compound represented by CB and 10 parts of polycarbonate resin (Panrye L-L manufactured by Tijin) were dissolved in 80 parts of tetrahydrofuran, and the pyromellitic anhydride represented by the aromatic polycarboxylic acid 0e described above was dissolved in the hydrazone compound CB. -1), the molar concentration is 0 to o, i
A coating liquid obtained by adding the coating solution in six steps within the range of 0% was applied using a wire bar to a dry film thickness of 15 μm to form a charge transport layer. The six types of photoreceptors obtained in this way were used as photoreceptor L Z a 4. a 6.

Photoreceptor L2. created in this way. a4. ! Regarding xa,
The 0 repetition test was carried out using a photoconductor measuring device.
．． Exposure for 1 second to white light with an illuminance of 5QLux was performed for 5 seconds, and this cycle was repeated and sensitivity etc. were measured after a certain number of times. Sensitivity measurements were performed by irradiating white light with an illuminance of 0.5 luX to 10.01 µX stepwise at a constant speed after charging at 16 KV for the 1st and 250th time, and drawing a light attenuation curve. . The results are shown in Table 1. In the table, Vr is the residual potential after 3 seconds of exposure, and E1/2 is the surface potential.
It represents the amount of exposure required to reduce the temperature from 5 oov to -250 cm, the number of times represents the number of repetitions, and the amount added represents the amount of aromatic polycarboxylic acid added.

Photoreceptor 1 to which aromatic polycarboxylic acid is not added has a high Vr at the initial stage of use, and also has a high Vr after repeated use.
The change in r is large. 0.10% aromatic polycarboxylic acid
The added photoreceptor 6 had a large change in El/2. The photoreceptor "I, 5" to which aromatic polycarboxylic acid was added in the range of 0.01 to 0.04% had Vr,
It can be seen that Eu/2 is stable.

Example 2 Photoreceptor 7. A charge generation layer having the same structure as in Example 1 was formed as &αio, and a hydrazone compound 10 part represented by (F notation chemical formula CB-3) and polycarbonate fat (Panlite L manufactured by Tijin Co., Ltd.) were added. 10 parts of tetrahydrofuran was dissolved in 80 parts of tetrahydrofuran, and the mixture of the above-mentioned polycarboxylic acids (1) and (2) and phthalic acid was added to the hydrazone compound to give a molar concentration of O to 1.
A coating solution obtained by changing the proportion within the range of 0.5% in four steps was applied using a wire bar to form a charge generation layer so that the 2-dry film thickness was 15 μm. The four types of photoreceptors obtained in this way were used as photoreceptor 7. Let it be aαlO.

Photoreceptor 7 thus obtained. &αlO was repeatedly tested in the same manner as in Example 1.

The results are shown in Table 2. In the table, Vr, El/2, number of times, and amount added have the same meanings as in Table 1.

Table 2 Photoreceptor 7 to which aromatic polycarboxylic acid is not added has Vr
is large, and the change in Vr is large when used repeatedly. It can be seen that the photoreceptor a9.10 containing aromatic polycarboxylic acid in the range of 0.1 to 0.5% has stable Vr and El/2 even after repeated use.

Claims (1)

[Claims] 1. A laminated photoreceptor comprising a charge generation layer and a charge transport layer laminated on a conductive support, wherein the charge generation layer contains a disazo pigment represented by the following general formula [I]. A laminated photoreceptor characterized in that the charge transport layer contains an aromatic polycarboxylic acid represented by the following general formula [II]. General formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] [In the formula, R_1 and R_2 represent halogen. ] General formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [II] [In the formula, n represents an integer from 2 to 6. Adjacent carboxyl groups may form an acid anhydride. 2. The laminated photoreceptor according to claim 1, wherein the charge transport further contains a hydrazone compound, and the aromatic polycarboxylic acid is pyromellitic anhydride.