JPS62287256A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body superior in sensitivity and small in the change with the lapse of time by incorporating a specified trisazo pigment and specifying an amount of chlorinated solvent remaining in a photosensitive layer. CONSTITUTION:The photosensitive layer of the electrophotographic sensitive body formed in a coating step using a halogenated solvent contains as a charge generating material one of the trisazo pigments represented by formula I in which X is an aromatic ring or the like; A<1> is a group represented by formula II or III; each of Ar<1> and Ar<2> is an optionally substituted aromatic ring, such as benzene ring; and each of R<1> and R<2> is lower alkyl or the like. An amount of halogenated solvent remaining in the photosensitive layer is regulated to <=500wt. ppm of the total photosensitive layer, thus permitting the electrophotographic sensitive body using said trisazo pigment as the charge generating material to be improved in sensitivity and the change characteristics with the lapse of time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an organic electrophotographic photoreceptor using a specific trisazo pigment as a charge generating substance.

Conventionally, electrophotographic photoreceptors have been known in which a photosensitive layer containing an organic conductive substance such as an azo pigment as an active ingredient is provided on a conductive support.

These organic electrophotographic photoreceptors have various excellent physical properties, but one of their major features is that a photosensitive layer can be formed by a coating process.

Although various organic photosensitive materials have been proposed, the trisazo pigment having a triphenylamine skeleton described in Japanese Patent Application Laid-Open No. 53-132347 has excellent properties as a charge-generating substance.

Although various types of electrophotographic photoreceptors using this trisazo pigment can be considered, a functionally separated type in which the photosensitive layer is constructed from a laminated structure of a charge generation layer and a charge transfer layer is typical. This photoreceptor is usually manufactured as follows. First, a charge generation layer coating solution is prepared by dispersing or dissolving a charge generation substance and, if necessary, a resin binder in a solvent, and this is coated on a conductive support directly or via an undercoat layer. Dry to form a charge generation layer. Next, the charge transfer substance and the resin binder are dissolved or dispersed in a solvent, coated on the charge generation layer, and dried to form a charge transfer layer.

When forming a photosensitive layer through such a coating process,
There is a wide range of support materials to choose from, and the productivity is extremely good, making it industrially advantageous.

Tetrahydrofuran and the like have been used as this solvent, but when the above-mentioned trisazo pigment is used, there is a problem in the storage life of the charge generation layer coating solution, which is an industrial problem.

Although a wide variety of studies have been conducted on the effects of charge-generating substances and resin binders on photoreceptor characteristics, relatively little research has been done on coating solvents.

The present invention provides an electrophotographic photoreceptor in which a photosensitive layer containing a specific trisazo pigment is formed by a coating method, which has excellent sensitivity.
Moreover, it is an object of the present invention to provide a photoreceptor that exhibits little change over time.

Another object of the present invention is to provide a photoreceptor with excellent productivity.

Highlights and Advantages The electrophotographic photoreceptor of the present invention has a photosensitive layer formed through a coating process using a halogen solvent, and contains a charge generating substance represented by the following general formula (r) in the photosensitive layer. The electrophotographic photoreceptor containing the trisazo pigment shown above is characterized in that the amount of residual halogenated solvent in the photosensitive layer is 500 weight Pρm or less.

During wiping, A1 is , where X+ Ar1. A, r2. R1,R
2 is as follows.

X: An aromatic ring such as a benzene ring or a naphthalene ring, or a hetero ring such as an indole ring, a carbazole ring, or a benzofuran ring, or a substituted product thereof, Ar': An aromatic ring such as a benzene ring or a naphthalene ring, or dibenzofuran a heterocyclic ring or a substituted product thereof, A r ”: an aromatic ring such as a benzene ring or a naphthalene ring, or a substituted product thereof, R1: hydrogen, a lower alkyl group or a phenyl group, or a substituted product thereof, R2, (lower alkyl group, phenyl group, carboxyl group or ester thereof) The present invention will be described in more detail below with reference to the accompanying drawings.

FIG. 1 is a sectional view illustrating the layer structure of an electrophotographic photoreceptor according to the present invention. A charge generation layer 1 is provided on the conductive support 11.
5 and the charge transfer layer 17 are sequentially laminated to form the photosensitive layer 13.
It consists of The charge generation layer 15 is formed by uniformly dispersing a charge generation substance, and a trisazo pigment represented by the following general formula (1) is used as the charge generation substance.

■ N=N-A1 (in the formula, A1 is, where X, A rl, A r2. R"
, R'' are as follows.

X: An aromatic ring such as a benzene ring or a naphthalene ring, or a hetero ring such as an indole ring, a carbazole ring, or a benzofuran ring, or a substituted product thereof.

Ar′: aromatic ring such as a benzene ring or naphthalene ring, or a hetero ring such as a dibenzofuran ring, or a substituted product thereof; Ar”: an aromatic ring such as a benzene ring or naphthalene ring or a substituted product thereof; R1: Hydrogen, lower alkyl group, phenyl group, or a substituted product thereof, R2 = lower alkyl group, phenyl group, carboxyl group or ester thereof) Specific examples of this trisazo pigment are as follows, and are disclosed in JP-A-53-132347. It is explained in detail in the issue.

(Hereafter the margin) --・-1-・ N=N-A1 (Hereafter the margin) Pigment practice 1 Pigment & 1 Pigment tooth, 1 11tali 1 Pigment practice
1. Any resin binder can be used as long as it has film-forming properties and insulating properties, such as polyamide, polyurethane, polyester resin, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, and polyester resin. Examples include vinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide.

It is appropriate to use the resin binder in an amount of 0 to 100 parts by weight, preferably 1 to 100 parts by weight, based on 100 parts by weight of the charge generating substance.
It is 0 to 50 parts by weight.

The thickness of the charge generation layer 15 is suitably about 0.05 to 1 μm, preferably 0.1 to 0.5 μm.

The charge transfer layer 17 contains a charge transfer substance and a resin binder, and may also contain a plasticizer, a leveling agent, etc., if necessary.

Charge transfer substances include poly-N-vinylcarbazole and its derivatives, poly-carbazolylethyl glutamate and its derivatives.

Pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives 9-(p-diethylaminostyryl)anthracene, 1,1-bis-(4-di benzylaminophenyl) propane, styryl anthracene, styryl pyrazoline, phenylhydrazones, α
- Electron-donating substances such as phenylstilbene derivatives can be mentioned.

Binders include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride. , polyarylate resin,
Phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyltoluene, poly-N-
Examples include thermoplastic or thermosetting resins such as vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyred resin.

The appropriate thickness of the charge transfer layer 17 is about 5 to 100 μff1.

The conductive support 11 may be a plastic film on which aluminum, nickel, chromium, nichrome, copper, tin oxide, indium oxide, etc. is vapor-deposited, a plate made of aluminum, nickel, stainless steel, etc., or a film made of these materials; ．． 1
．． (2) After forming the tube into a blank tube using extrusion, drawing, etc., it is possible to use a tube that has been surface-treated by cutting, superfinishing, polishing, etc.

In the present invention, at least one of the photosensitive layer 13, that is, the charge generation layer 15 and the charge transfer layer 17, is formed through a coating process using a halogen solvent. Examples of halogenated solvents include dichloromethane, dichloroethane, monochlorobenzene, dichlorobenzene, tetrachloroethane,
Examples include chloroform, carbon tetrachloride, trichlorethylene, tetrachlorethylene, chlornaphthalene, etc.
These may be used alone or in combination of two or more.

Moreover, a solvent other than the halogen-based solvent can be used in combination with the halogen-based solvent. As such a solvent, benzene, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, dioxane, tetrahydrofuran, cyclohexanone, methyl cellosolve, ethyl cellosolve, etc. are used alone or in combination. Note that either the charge generation layer or the charge transfer layer may be formed without using a halogen solvent.

The charge generation layer is prepared by dispersing or dissolving the trisazo pigment of the general formula (I) and, if necessary, a resin binder in a solvent to prepare a charge generation layer coating solution, which is coated by dip coating, a doctor blade, a wire blade, or an air knife. It can be formed by applying the coating onto a support using, for example, and drying it.

When a halogenated solvent is used as the solvent, the amount of residual halogenated solvent in the charge generation layer can be suppressed by adjusting the heating temperature and heating time during drying.

The charge transfer layer can be formed by dissolving or dispersing the charge transfer substance and the binder resin in a solvent to prepare a charge transfer layer coating solution, and applying this on the charge generation layer in the same manner as described above and drying it. When a halogenated solvent is used as the solvent, the amount of residual halogenated solvent in the charge transfer layer can be controlled by adjusting the heating temperature and heating time during drying.

In the present invention, by controlling the amount of residual halogenated solvent in the entire photosensitive layer to 500 ppm by weight or less, the sensitivity and temporal fluctuation characteristics of an electrophotographic photoreceptor using the trisazo pigment of general formula (1) as a charge generating substance can be improved. can be improved.

When cyclohexanone, benzene, or the like is used as a solvent, sensitivity and temporal variation characteristics are not sufficient compared to when a halogen solvent is used. Furthermore, general formula (T)
The charge generation layer coating solution (photosensitive layer coating solution) containing the trisazo pigment has poor stability over time when tetrahydrofuran or cyclohexanone is used as a solvent, resulting in uneven coating of the charge generation layer. . On the other hand, when a halogen-based solution is used as a solvent for this charge generation layer coating solution, its stability is significantly improved. It is extremely important that the charge generation layer coating liquid has excellent stability in order to industrially form a charge generation layer with stable characteristics.

FIG. 2 is a sectional view showing another example of the structure of the electrophotographic photoreceptor of the present invention, except that an undercoat layer 19 is provided between the conductive support 11 and the charge generation layer 15. It is similar to that in Figure 1. The undercoat layer 19 improves chargeability, adhesion, and surface properties of the substrate.

It is used to prevent moiré by dispersing a pigment having a higher refractive index than the resin forming the subbing layer, such as TiO2 or ZnS. Examples of this resin include copolymerized polyamide, alcohol-soluble nylon, polyvinyl butyral (Japanese Patent Application Laid-open No. 59-36258), water-soluble polyvinyl butyral (Japanese Patent Application Laid-Open No. 60-232553, 60-60).
-232554) etc. can be used.

The undercoat layer 17 has a suitable thickness of about 0.01 to 10 μm,
Preferably it is 0.01 to 5 μm.

According to the present invention, by controlling the amount of residual halogenated solvent in the photosensitive layer formed by a coating process containing a specific trisazo pigment and using a halogenated solvent to 500 ppm by weight or less, excellent sensitivity can be achieved. Furthermore, it is possible to realize an electrophotographic photoreceptor with a small residual potential and little change over time.

Examples 1 to 3 and Comparative Examples 1 and 2 The following trisazo pigments 3 parts by weight Polyvinyl butyral 1 part by weight (Sekisui Chemical Co., Ltd. Esresoku BL-1) Cyclohexanone 1
00 parts by weight 1.2-dichloroethane 150 parts by weight The above composition was dispersed in a ball mill for 24 hours to obtain a charge generation layer coating solution.

The above charge generation layer coating solution was applied onto a polyethylene terephthalate film (thickness: 75 μm) on which aluminum was vapor-deposited so that the dry film thickness was 0.2 μm.
2, the drying temperature was changed and drying was carried out for 2 minutes to form a charge generation layer.

A charge transfer layer coating solution having the composition shown below is applied onto this layer to a dry film thickness of 20 μm, and dried at 120° C. for 5 minutes to form a charge transfer layer. I got it.

Hydrazone compound with the following structure 90 parts by weight Polycarbonate ioo parts by weight (Panlite L-1250 manufactured by Teijin Chemicals) Tetrahydrofuran
800 parts by weight Comparative Example 3 An electrophotographic photoreceptor was obtained in the same manner as in Example 1, except that 1°2-dichloroethane in the charge generation layer coating solution in Example 1 was replaced with cyclohexanone.

The electrophotographic photoreceptor obtained as described above.

Electrostatic Paper Analyzer (SP-
428, ■Kawaguchi Denki Seisakusho (Newly manufactured)), the potential V after 10 seconds at a corona discharge voltage of -6KV.

(Volt), residual potential VR after 15 seconds of exposure at intensity 5 lux (Volt), roughness + lE position vllll is l/1
Exposure amount E required to attenuate to 0, □. (lux-
8ec) was measured (pre-fatigue characteristics).

Furthermore, charging at a corona discharge voltage of -6 KV and exposure intensity of 5
The photoreceptor was simultaneously exposed to light for 30 minutes to fatigue the photoreceptor, and the characteristics of the photoreceptor after fatigue were measured in the same manner as above (post-fatigue characteristics).

Furthermore, the amount of residual 1,2-dichloroethane (residual EDC (ppm
) ) were measured and shown in Table 2. Quantitative analysis of the amount of residual solvent was performed using a gas chromatograph mass spectrometer (TE600) manufactured by Nippon Parian ■.

(The following are blank spaces) Table 2 Examples 4 and 5 and Comparative Examples 3 to 6 Electrophotographic exposure was carried out in the same manner as in Example 1, except that the charge generation layer coating solution and the charge transfer layer coating solution had the following compositions. created a body. However, the charge generation layer was formed by drying at 80° C. for 5 minutes. The charge transfer layer was dried under the drying conditions shown in Table 3 below.

Charge: Raw layer coating: 3 parts by weight of the following trisazo pigments: 1 part by weight of polyester resin (manufactured by Toyobo ■, Byron 200) Cyclohexanone: 120 parts by weight (Manufactured by Unitika ■, u-aooo) Tetrahydrofuran 500 parts by weight Dichloromethane 300 parts by weight H3 Comparative Example 7 In Example 4, except that dichloromethane in the charge generation layer was replaced with cyclohexanone and dichloromethane in the charge transport layer was replaced with tetrahydrofuran.
An electrophotographic photoreceptor was produced in the same manner as in Example 4.

The photoreceptor characteristics of the above photoreceptor were evaluated in the same manner as described above, and the results are shown in Table 3.

Table 3 ×1) Remaining amount of MDC (dichloromethane) in the entire photosensitive layer.

Examples 6 to 8 and Comparative Examples 8 and 9 On the same conductive support as in Example 1, coat the undercoat layer coating solution with the following composition so that the dry film thickness is 5 μm, dry it, and apply the undercoat layer. formed a layer.

Undercoat layer coating Tie, powder 40 parts by weight (manufactured by Ishihara Sangyo ■, Tiebake R-670) Alcohol-soluble nylon 50 parts by weight (manufactured by Toshihara ■, Amiran CM-80
00) Ethanol 100 weight.

An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that two or less charge generation layer coating liquids and charge transfer layer coating liquids were used thereon.

However, the charge generation layer was dried by heating at 100° C. for 2 minutes. Further, the charge transfer layer was dried by heating under the conditions shown in Table 4 below.

(Left below) Densei Coating Trisazo pigment shown below 3 parts by weight Cyclohexanone 160 parts Stilbene compound shown below 70 parts by weight Polyvinylcarbazole
40 parts by weight Styrene/metal methacrylate copolymer 80 parts by weight Chlorobenzene 700 parts by weight Comparative Example 1
0 An electrophotographic photoreceptor was prepared in the same manner as in Example 6, except that chlorobenzene in the charge transfer layer coating solution was replaced with toluene.

The electrophotographic properties of the above photoreceptor were measured and the results are shown in Table 4.

(Leaving space below) Table 4 *2) Prepare two glass tubes with an inner diameter of 6m and a length of 40mm and stand them vertically. The charge generation layer coating solution of Example 1 and the charge generation layer coating solution of Comparative Example 3 were each filled to a height of 30 cm.

When left as is for 3 days, the coating solution of Example 1 was
It remained as unclear as it had been in the beginning. On the other hand, comparative example 3
The charge generation layer coating solution caused sedimentation, and the upper 5 cm became transparent.

That is, the charge generation layer coating solution of Example 1 is a stable coating solution with little change over time, but the charge generation layer coating solution of Comparative Example 3 is an unstable coating solution that causes sedimentation over time. It turned out to be an industrial fluid.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing an example of the structure of an electrophotographic photoreceptor according to the present invention. 11... Conductive support 13... Photosensitive layer 15.
...Charge generation layer 17...Charge transfer layer 19...
- Subscription Calendar Procedural Amendment Form August 18, 1985 Commissioner of the Patent Office Black 1) Mr. Yu Akira ■, Indication of the case Patent Application No. 130929 of 1985 2, Name of the invention Electrophotographic photoreceptor 36 Person making the amendment Relationship to the case Patent applicant 1-3-6 Nakamagome, Ota-ku, Tokyo (674) Ricoh Co., Ltd. Representative Hama 1) Hiro 4, Agent 5, ``Detailed description of the invention'' in the specification to be amended 6. Details of the amendment (1) The structure of A1 in Pigment N (11-25) on page 14 of the specification is corrected as follows. (2) In lines 11 to 9 from the bottom of page 23 of the specification, " Corona discharge...
...Potential V. (Volt),” should be corrected as follows. “Potential Vm (V
olt), potential V after 10 seconds of dark decay. (Volt),” (3) Amend page 25 of the same as shown in the attached sheet. (4) Amend page 28 as per Attachment 2. (5) Amend page 32 of the same as shown in Attachment 3. 7. List of attached documents (1) Attachments 1 to 3 1 or more attachments 1 x 1) Unable to measure due to large dark decay. *2) No EDC used. Attachment 2 *1) This is the residual amount of MDC (dichloromethane) in the entire photosensitive layer. ×2) Unable to measure due to large dark decay. *3) MDC not used. Attachment 3 ×1) CB = Chlorbenzene ×2) Unable to measure due to large dark decay. *3) No CB used.

Claims (1)

[Claims] 1. It has a photosensitive layer formed through a coating process using a halogenated solvent, and contains a trisazo pigment represented by the following general formula (I) as a charge generating substance in the photosensitive layer. An electrophotographic photoreceptor, characterized in that the amount of residual halogenated solvent in the photosensitive layer is 500 ppm by weight or less. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) (In the formula, A^1 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, where X, Ar ^1, Ar^2, R^1, R^
2 is as follows. X: an aromatic ring such as a benzene ring or a naphthalene ring, or a hetero ring such as an indole ring, a carbazole ring, or a benzofuran ring, or a substitute thereof; Ar^1: an aromatic ring such as a benzene ring or a naphthalene ring;
or a hetero ring such as a dibenzofuran ring or a substituted product thereof; Ar^2: an aromatic ring such as a benzene ring or a naphthalene ring or a substituted product thereof; R^1: hydrogen, a lower alkyl group or a phenyl group, or a substituted product thereof; R^2: lower alkyl group, phenyl group, carboxyl group or ester thereof)