JPS63269155A - Photosensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body high in photosensitivity and stable in electrophotographic characteristics even in repeated uses by incorporating a specified styryl compound. CONSTITUTION:The photosensitive body contains the styryl compound represented by formula I in which R1 is cyano or halogen; Ar1 is aryl; each of Ar2 and Ar3 is an aromatic hydrocarbon group or aromatic heterocyclic group; and n is 0 or 1. This styryl compound is used as the photoconductive material of a photosensitive body or only the superior electric charge transfer ability of said compound is used for the charge transfer layer of a functionally separated type electrophotographic sensitive body, thus permitting the obtained electrophotographic sensitive body to be enhanced in sensitivity and to exhibit characteristics stable even at the time of repeated uses.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a photosensitive layer containing a styryl compound as a main component.

Conventional Technologies and Problems As electrophotographic photoreceptors, there are two types: a functionally separated type in which a charge generation layer and a charge transport layer are laminated on a conductive support, and a photoconductive layer in which photoconductive particles are dispersed in a resin. A dispersed type formed on a support is widely known.

In the functionally separated type, the basic functions of a photoreceptor, such as generation and transport of charge carriers, are assigned to separate substances, resulting in high surface potential, large charge retention, high photosensitivity, and stable repeatability. A photosensitive layer can be obtained. It is known that a large number of compounds are effective for both functionally separated charge generation materials for charge generation and charge transport materials for charge transport. For example, many charge transport layers using low-molecular organic photoconductors have been proposed. However, the method using 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole described in U.S. Patent No. 3,189,447 is compatible with the binder. It has low properties and crystals tend to precipitate. Furthermore, those using diarylalkane derivatives described in U.S. Pat. No. 3,820,989,
Although the compatibility with the binder is good, there are still significant points that need to be improved in terms of initial sensitivity and residual potential characteristics, as well as sensitivity changes and durability after repeated use, such as sensitivity changes occurring when used repeatedly. be.

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

That is, the gist of the present invention is the following general formula [I]; Each represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.

n represents the number O or l. ] The present invention is characterized by an electrophotographic photoreceptor containing a styryl compound represented by the following.

In the present invention, by using the styryl compound represented by the general formula [I] as a photoconductive substance of a photoreceptor, or by utilizing only the excellent charge transport ability of the styryl compound of the present invention, a functionally separated type When used in the charge transport layer of an electrophotographic photoreceptor, it has excellent film properties, excellent electrophotographic properties such as charge retention ability, sensitivity, and residual potential, and stable characteristics with little fatigue deterioration even after repeated use. It is possible to produce an electrophotographic photoreceptor that can exhibit the following properties.

Preferred specific examples of the styryl compound represented by the general formula [1] of the present invention include, for example, those having the following structural formula, but are not limited thereto.

J C,H.

The styryl compound represented by the general formula [I] is, for example, the following general formula [■Koni R, OR.

In the formula, RISArl has the same meaning as [1], and Rt and Rs represent an alkyl group, a cycloalkyl group, an aralkyl group, and an aryl group that form a phosphonium salt. ] The phosphorus compound represented by the following general formula [I] [where Ar, , Are
can be obtained by condensation with an acrolein compound represented by [same meaning as I]. R1 and Rx of the phosphorus compound represented by the general formula [■] are preferably a cyclohexyl group, a benzyl group, a phenyl group, or a lower alkyl group.

Examples of the reaction solvent in the above method include hydrocarbons,
Alcohols and ethers are good; methanol, ethanol, isopropanol, butanol, 2-methoxyethanol, 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, dioxane, tetrahydrofuran, toluene, xylene dimethyl sulfoxide, N,
N-dimethylformamide, N-methylpyrrolidone, 1
．． Examples include 3-dimethyl-2-imidazolidinone. Among them, polar solvents such as N,N-dimethylformamide and dimethylsulfoxide are preferred.

As the condensing agent, alcoholades such as caustic soda, caustic potash, sodium amide, sodium hydrogen and sodium methylate, and potassium t-butoxide are used.

The reaction temperature can be selected over a wide range from about 0.degree. C. to about 100.degree. Preferably it is 10°C to 80°C.

The compound [I[] used in the present invention can also be prepared by using a corresponding quaternary phosphonium salt, such as a triphenylphosphonium salt, in place of the phosphorus compound, and
It can be obtained by condensing it with an aldehyde compound [I[1] through a phosphorylene step according to the method of .ttig). These styryl compounds may be used alone or in combination.

Examples of the structure of an electrophotographic photoreceptor using the styryl compound of the present invention are schematically shown in FIGS. 1 to 5.

Figure 1 shows a photoreceptor in which a photosensitive layer (4) containing a photoconductive material (3) and a charge transporting material (2) as a binder is formed on a substrate (1). The styryl compound of the present invention is used.

FIG. 2 shows a functionally separated photoreceptor having a charge generation layer (6) and a charge transport layer (5) as photosensitive layers.
A charge transport layer (5) is formed on the surface of 6). The styryl compound of the present invention is blended into the charge transport layer (5).

Figure 3 shows a functionally separated photoreceptor having a charge generation layer (6) and a charge transport layer (5) as in Figure 2, but contrary to Figure 2, the surface of the charge transport layer (5) is A charge generation layer is formed.

FIG. 4 shows an additional surface protective layer (
, 7), and the photosensitive layer (4) may be of a functionally separated type in which the photosensitive layer (4) is separated into a charge generation layer (6) and a charge transport layer (5).

FIG. 5 shows an intermediate layer (8) between the substrate (1) and the photosensitive layer (4).
), and the intermediate layer (8) improves adhesion,
It can be provided to improve coating properties, protect the substrate, and improve charge injection from the substrate to the photoconductive layer. As the intermediate layer, polyimide resin, polyester resin, polyvinylbutyral resin, casein, etc. may be used. The photoreceptor of this embodiment may also have a photosensitive layer of a functionally separated type.

The electrophotographic photoreceptor of the present invention can be prepared by dissolving or dispersing the styryl compound represented by the general formula [I] together with a binder in a suitable solvent, and optionally adding a photoconductive material, an electron-withdrawing compound, or a sensitizing dye. , a coating solution obtained by adding other pigments is applied onto a conductive substrate and dried, usually for 5 minutes.
It can be manufactured by forming a photosensitive layer with a thickness of 1 to 30 μm, preferably 6 to 20 μm.

Specifically, a functionally separated photoreceptor has a structure similar to that of the photoreceptor shown in FIG. The charge generating material is vacuum deposited on the surface, or a coating solution prepared by dispersing the charge generating material in a suitable solvent or, if necessary, a solution containing a binder resin, is applied and dried to form a charge generating layer. A charge transporting layer is obtained by applying a solution of a styryl compound and a binder resin dissolved in a suitable solvent as a charge transporting material and drying the film to form a charge transporting layer. For example, metal-free phthalocyanine, titanyl phthalocyanine,
Phthalocyanines such as alumincrophthalocyanine are used. Further, in the case of dispersing, for example, a disazo pigment or the like is used. The thickness of the charge generation layer at this time is 4 .mu.m or less, preferably 2 .mu.m or less, and the charge transport layer has a thickness of 3 to 30 .mu.m, preferably 5 to 20 .mu.m. The proportion of the styryl compound in the charge transport layer is 0.02 to 2 parts by weight, preferably 0.02 to 2 parts by weight, per 1 part by weight of the binder resin.
．． The amount is preferably 0.03 to 1.3 parts by weight. Further, other charge transport materials may be used in combination. In the case of polymeric charge transport materials that can themselves be used as binders, no other binder may be used. The structure of the photoreceptor may be similar to the photoreceptor shown in FIG. 3 described above, in which a charge transport layer is formed on a conductive support, and a charge generation layer is laminated thereon.

A dispersion type photoreceptor, which is composed of a photoconductive layer formed on a conductive support and has a structure similar to that of the photoreceptor shown in FIG. It is obtained by dispersing it in a solution, coating it on a conductive support, and drying it to form a photoconductive layer. The thickness of the photoconductive layer at this time is 3 to 30 μm, preferably 5 to 20 μm.
μm is good.

If too little photoconductive material is used, the sensitivity will be poor;
If the amount is too large, the charging property will deteriorate and the strength of the photoconductive layer will become weak.The amount of photoconductive material in the photoconductive layer is preferably 0.01 to 2 parts by weight per 1 part by weight of the resin. is 0.
05 to 1 part by weight is good, and the proportion of the styryl compound is 1 part by weight of the resin.
0.01 to 2 parts by weight, preferably 0.0 parts by weight
2 to 1.2 parts by weight is preferred. It may also be used in combination with a polymeric photoconductor such as polyvinylcarbazole, which itself can be used as a binder. It may also be combined with other charge transport materials, such as hydrazone compounds.

The charge-generating materials used in the functionally separated type electrophotographic photoreceptor of the present invention and the photoconductive materials used in the dispersed type include bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthine dyes, and cyanine. pigments, styryl pigments, pyrylium dyes, azo pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indathrone pigments, squarylium pigments,
Organic substances such as phthalocyanine pigments, selenium,
Examples include inorganic substances such as tellurium, selenium/arsenic, cadmium sulfide, and amorphous silicon. In addition to this, any material can be used as long as it absorbs light and generates charge carriers with extremely high efficiency.

Further, two things that can be used as a binder are electrically insulating resins, and all known thermoplastic resins, thermosetting resins, photocurable resins, and photoconductive resins can also be used. Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers,
Ionically crosslinked olefin copolymer (ionomer), styrene-butadiene block copolymer, polyarylate,
Polycarbonate, vinyl chloride-vinyl acetate copolymer,
Thermoplastic binders such as cellulose ester, polyimide, and styrene resins; Thermosetting binders such as epoxy resins, urethane resins, silicone resins, phenol resins, melamine resins, xylene resins, alkyd resins, and thermosetting acrylic resins; light Curable resin: photoconductive resin such as poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, etc. These can be used alone or in combination. It is desirable that these electrically insulating resins have a volume resistivity of 1X10uΩ·Gx or more when measured alone. More preferred are polyester resin, polycarbonate, and acrylic resin.

The electrophotographic photoreceptor of the present invention contains a binder as well as a plasticizer such as halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl phthalate, 0-terphenyl, chloranil, tetracyanoethylene, 2,4.
Electron-withdrawing sensitizers such as 7-dolinitro-9-fluorenone, 5,6-dicyazbenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3,5-dinitrobenzoic acid, methyl violet, rhodamine B1 cyanine dye, Sensitizers such as pyrylium salts and thiapyrylium salts may also be used.

The electrophotographic photoreceptor formed in this manner has an adhesive layer, an intermediate layer, an intermediate layer,
It may have a surface protective layer.

Materials used for the intermediate layer include polymers such as polyimide, polyamide, nitrocellulose, polyvinyl butyral, and polyvinyl alcohol as they are, or in which low-resistance compounds such as tin oxide and indium oxide are dispersed, aluminum oxide, zinc oxide, A vapor deposited film of silicon oxide or the like is suitable.

The thickness of the intermediate layer is preferably 1 μm or less.

Materials used for the surface protective layer include acrylic resin,
Suitable materials include polymers such as polyaryl resins, polycarbonate resins, and urethane resins as they are, or those in which low-resistance compounds such as tin oxide and indium oxide are dispersed. Additionally, organic plasma polymerized films can also be used. The organic plasma polymerized film can be prepared with oxygen, nitrogen,
It may contain a halogen, an atom of group (I) or group (IV) of the periodic table.

Further, the thickness of the surface protective layer is desirably 5 μm or less.

As described above, the styryl compound of the present invention can be easily produced, and a photoreceptor containing it can be used as a functionally separated type or a dispersed type, and can be combined with various charge-generating materials and binder resins. , and optionally other charge transport materials can be added. Therefore, the electrophotographic photoreceptor containing the styryl compound of the present invention is extremely easy to manufacture and has a wide range of uses, and the styryl compound effectively prevents optical fatigue, resulting in excellent repeatability, improved sensitivity, and surface potential. There will be little change.

The present invention will be explained in more detail below using examples.

Synthesis Example (Compound [3]) Phosphonate 2.539 represented by the following formula; and aldehyde compound 3.60y represented by the following formula were dissolved in dimethylformamide 30xQ, and heated to 30 to 40°C. , potassium-ter in dimethylformamide 70ytQ
- A suspension containing 59 butoxides was added dropwise. Thereafter, the mixture was stirred at room temperature for 8 hours and then left in the apparatus overnight. The resulting mixture was added to 900 ml of ice water, neutralized with dilute hydrochloric acid, and
After a few minutes, the precipitated crystals were filtered. The filtered product was filtered with water and further purified by recrystallization using acetonitrile to obtain 3.7 g of yellow needle crystals. (Yield 82%) Elemental analysis is as follows.

Example! 0.45 parts of a disazo compound represented by the following general formula (A) and 0.45 parts of a polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.) were dispersed together with 50 parts of cyclohexanone using a sand grinder.

The obtained disazo compound dispersion was applied onto a 100 μm thick aluminized mylar using a film applicator.
It was coated to a dry film thickness of 0.39 parts m'' and dried. 70 parts of styryl compound [2] and polycarbonate resin (K
A solution prepared by dissolving 70 parts of -13 parts (manufactured by Teijin Kasei Ltd.) in 400 parts of 1,4-dioxane was applied to a dry film thickness of 16 μm to form a charge transport layer. In this way, an electrophotographic photoreceptor having a two-layer photosensitive layer was obtained.

The photoreceptor thus obtained was heated to -6KV using a commercially available electrophotographic copying machine (EP-470Z manufactured by Minolta Camera Co., Ltd.).
Corona charged with initial surface potential■. (V), exposure mE required to reduce the initial potential to 1/2, /1(lux-
sec), and the decay rate DDR, (%) of the initial potential when left in the dark for 1 second was measured.

Examples 2 to 4 Same structure as in Example 1, except that styryl compounds [3, [4], and [6] were used in place of styryl compound [2] used in Example 1. A photoreceptor was produced.

The thus obtained photoreceptor was treated in the same manner as in Example 1. ,E,/,DDRl was measured.

Example 5 0.45 parts of a disazo compound represented by the following general formula (B) and 0.45 parts of polystyrene resin (molecular weight 40,000) were dispersed together with 50 parts of cyclohexanone using a sand grinder. The obtained dispersion of the disazo compound was applied onto a 100 μl thick aluminized Mylar using a film applicator so that the dry film thickness was 0.3 g/11”, and then dried. 70 parts of styryl compound [10] and 70 parts of polyarylate resin (U-100: manufactured by Unitika Co., Ltd.) were placed on the charge generation layer.
A charge transport layer was formed by dissolving 400 parts of 1,4-dioxane in a solution having a dry film thickness of 16 .mu.m. In this way, an electrophotographic photoreceptor having a photosensitive layer made of 2B was produced.

Examples 6 to 8 Same structure as in Example 5, except that styryl compounds [11], [17], and [21] were used in place of styryl compound [10] used in Example 5. A photoreceptor was produced.

The thus obtained photoreceptor was treated with vo, E, /! in the same manner as in Example 1. %DDR, was measured.

Example 9 50 parts of copper phthalocyanine and 0.2 parts of copper tetranitro phthalocyanine were dissolved in 500 parts of 98% concentrated sulfuric acid with sufficient stirring, and this was poured into 5,000 parts of water to form a photoconductive material composition of copper phthalocyanine and copper tetranitro phthalocyanine. After precipitating the product, it was filtered, washed with water, and dried at 120°C under reduced pressure.

10 parts of the photoconductive composition thus obtained was added to a thermosetting acrylic resin (Acrytic A405. Dainippon Ink Co., Ltd.).
) 22.5 parts, melamine resin (Super Beckamine J
820. (manufactured by Dainippon Ink Co., Ltd.) 7° 5 parts, the above-mentioned styryl compound 121]! 5 parts of methyl ethyl ketone and xylene were mixed in equal amounts in a ball mill bot with 100 parts of a mixed solvent and dispersed for 48 hours to prepare a photosensitive coating liquid. This coating liquid was applied onto an aluminum substrate, dried and thickened. A photoreceptor was prepared by forming a photosensitive layer with a thickness of approximately 15 μm.

The photoreceptor thus obtained was corona charged in the same manner as in Example 1, except that the voltage was +6 KV. ,E+/
*, DDR, was measured.

Examples 1O to 12 Same structure as in Example 9, except that styryl compounds [22], [27], and [28] were used in place of styryl compound [21] used in Example 9. A photoreceptor was produced.

With respect to the thus obtained photoreceptor, V was treated in the same manner as in Example 9. , E+/l, DDR, were measured.

Comparative Examples 1 to 4 Same structure as in Example 9, except that the following compounds (C), (D), (E), (F) were used in place of the styryl compound [21] used in Example 9. ) A photoreceptor was produced in exactly the same manner as in Example 9 except that each of the following was used.

Regarding the photoreceptor thus obtained, vo, E1/2, and DDRI were measured in the same manner as in Example 9.

Comparative Examples 5 to 7 Same structure as in Example 9, except that the following styryl compounds (G), (H), and (1) were used in place of the styryl compound [21] used in Example 9. A photoreceptor was produced in exactly the same manner as in Example 9 except for using the following.

Regarding the photoreceptor thus obtained, vo, E+/*, and DDR+ were measured in the same manner as in Example 9.

V of the photoreceptors obtained in Examples 1-12 and Comparative Examples 1-8.

The measurement results of ,E,/, ,DDR, are summarized in Table 1.

As can be seen from Table 1, the photoreceptor of the present invention has sufficient charge retention ability whether it is a multilayer type or a single layer type, and the dark decay rate is small enough to be used as a photoreceptor. It is clear from the data that the sensitivity is also excellent.

In addition, a commercially available electrophotographic copying machine (Minolta Camera Co., Ltd.)
A repeated live-photographing test was conducted on the photoconductor of Example 9 during positive charging using the product manufactured by EP-3502), and even after 1,000 copies were made, the gradation was excellent in the initial and final images, and there was no change in sensitivity. It can be seen that clear images are obtained and the photoreceptor of the present invention has stable repeatability.

The photoreceptor of the present invention contains the above-mentioned styryl compound, so it has excellent charge transport properties, a stable initial surface potential, a sufficiently small dark decay rate, and good charging properties. have sex. It also has fewer carrier traps and is highly sensitive.
Less light fatigue.

The electrophotographic photoreceptor obtained using the compound of the present invention effectively suppresses optical fatigue, shows less decrease in surface potential, less increase in residual potential, less change in sensitivity, and has stable electrophotographic properties when used repeatedly. Because it is highly sensitive, it is possible to obtain clear images.

Furthermore, styryl compounds are particularly effective as charge transport materials for functionally separated photoreceptors.

[Brief explanation of the drawing]

1 to 5 are schematic diagrams of photoreceptors according to the present invention, and FIGS. 1, 4, and 5 show dispersion type photoreceptors in which a photosensitive layer is laminated on a conductive support. Figures 2 and 3 show the structure of
The figure shows the structure of a functionally separated photoreceptor in which a charge generation layer and a charge transport layer are laminated on a conductive support.

Claims (1)

[Claims] 1. A photoreceptor characterized by containing a styryl compound represented by the following general formula [I]: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] [In the formula, R_1 is cyano group or halogen atom, Ar_
1 is an aryl group that may have a substituent, Ar_2, Ar
_3 independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group, each of which may have a substituent. n represents a number of 0 or 1. ]