JPH01155356A - Photosensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body superior in physical film property and electrophotographic characteristics, such as charge retaintivity, sensitivity, and residual potential, small in deterioration due to fatigue at the time of repeated uses and stable in characteristics by using a specified styryl compound as a photoconductor. CONSTITUTION:The electrophotographic sensitive body is provided on a conductive substrate 1 with the photosensitive layer 4 obtained by mixing into a binder resin a photoconductor 3 and as an electric charge transfer material 2 at least one of the styryl compounds represented by formula I in which each of R1 and R2 is alkyl, aralkyl, or aryl; each of Ar1 and Ar2 is a divalent aromatic monocyclic or condensed polycyclic hydrocarbon group; Ar3 is an aromatic monocyclic or condensed polycyclic hydrocarbon group or a heterocyclic group; R3 is H, OH, alkyl, aralkyl, or alkoxy; and n is an integer of 0-3, thus permitting charge transfer performance to be enhanced and electrifiability to be improved.

Description

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

Conventional techniques and problems As a photoreceptor, a functionally separated photoreceptor is formed by laminating a charge generation layer and a charge transport layer on a conductive support, and a photoconductive layer in which photoconductive particles are dispersed in a resin is used as a support. The dispersed type formed on the top 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 has compatibility with the binder. is low, and crystals tend to precipitate. Also, U.S. Patent No. 3.82
The diaryl alkane derivative described in Publication No. 0.989 has good compatibility with the binder, but changes in sensitivity occur when used repeatedly.
There are still significant points to be improved in terms of initial sensitivity and residual potential characteristics, changes in sensitivity upon repeated use, and durability. Japanese Patent Publication No. 58-57739 discloses a photoconductive material represented by the following formula [where R1-R2, Ar, to Ar3 represent the meanings stated in the above publication], but the above compound is It has amino groups at both ends, and is also compatible as above,
There are some points that need improvement, such as sensitivity.

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

That is, the gist of the present invention is the following general formula [I];
, R, each represents an alkyl group, an aralkyl group, or an aryl group that may have a substituent, and R1, R
2 may be combined to form a ring, or R1 or R2 may be combined with Ar and gold to form a ring. A r 1
, A r 2 may each have a substituent,
2 of aromatic monocyclic hydrocarbons or fused polycyclic hydrocarbons
Represents a valence group. A" represents the residue of an aromatic monocyclic hydrocarbon, a fused polycyclic hydrocarbon, or a heterocyclic compound.R1
represents hydrogen, hydroxyl group, alkyl group, aralkyl group, or alkoxy group. n represents an integer of O to 3].

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 a photoreceptor, it has excellent film properties, excellent electrophotographic properties such as charge retention ability, sensitivity, and residual potential, and exhibits stable characteristics with little fatigue deterioration even after repeated use. It is possible to produce a photoreceptor that can be used.

In the general formula [I], R and 1R represent an alkyl group, an aralkyl group, or an aryl group, each of which may have the following substituents.

Alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, ter-butyl, pentyl, etc. Aralkyl groups such as benzyl, p-methylbenzyl,
p-methoxybenzyl, phenethyl, phenylpropyl, etc. Aryl groups: e.g. phenyl, p-methylphenyl, p
-methoxyphenyl, p-ethylphenyl, p-ethoxyphenyl and the like.

Both R1 and R2 may be combined with a nitrogen atom to form a ring, such as a morpholine ring, a carbazole ring, a pyrrolidine ring, a pyridine ring, a quinoline ring, a piperidine ring, a virol ring, an indoline ring, a julolidine ring, etc., and R1 or R2 may be bonded to Ar.

Ar or Ar2 is independently an aromatic monocyclic hydrocarbon which may have a substituent, such as benzene, toluene, ethylbenzene, methoxybenzene, ethoxybenzene, etc., or a fused polycyclic hydrocarbon, such as naphthalene. , represents a divalent group such as anthracene, pyrene, phenanthrene, fluorene, etc.

Ar= is an aromatic monocyclic hydrocarbon such as benzene, a fused polycyclic hydrocarbon such as naphthalene, anthracene, pyrene, phenanthrene, fluorene, etc., or a heterocyclic compound such as dioxindane, N-ethylcarbazole,
indoline, tetrahydroquinoline, phenothiazine,
Represents residues such as phenoxazine, furan, and thiophene.

R3 has a number (n) of 1 to 3 and represents a hydrogen atom, a hydroxyl group, or the following group; Alkyl group; methyl, ethyl, propyl, isopropyl, butyl, isobutyl, ter-butyl, pentyl, etc.; Alkoxy group; methoxy , ethoxy, propoxy, benzyloxy, and other aralkyl groups; benzyl, 7-enethyl, phenylpropyl, etc.

Preferred specific examples of the styryl compound represented by general formula [11] of the present invention include those having the following structural formula, but are not limited thereto.

(Hereafter, margins) [101 [11] [12] [13] [14] [15] [16] [171 [18] [19] [20] [21] [221 [23] [241 [25] [ [I ], R2 and R6 represent an alkyl group, cycloalkyl group, aralkyl group, or aryl group forming a phosphonium salt. ] The phosphorus compound represented by the following formula [I[1]E, where R1, R8
, A r r, Ar has the same meaning as [I]]. −
R6 of the metal phosphide represented by the formula [11] is particularly 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,
Good for alcohols and ethers, such as methanol, ethanol, impropatol, butanol, 2-methoxyethanol, ■, 2-dimethoxyethane, bis(2-methoxyethyl) ether, dioxane, tetrahydrofuran, toluene, xylene dimethyl sulfoxide, N,
N-dimethylformamide, N-methylpyrrolidone, l
, 3-dimethyl-2-imidazolidinone, etc. 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 hydroxide and sodium methylate, potassium ter-butoxide and the like are used.

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

Moreover, the compound [I[) used according to the present invention can 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 with an aldehyde compound [111] through a phosphorylene step according to the method of tLig). These styryl compounds may be used alone or in combination.

A first example of the structure of a photoreceptor using the styryl compound of the present invention is shown below.
It is schematically shown in FIG. Figure 1 shows the base (1)
This is a photoreceptor on which a photosensitive layer (4) containing a photoconductive material (3) and a charge transporting material (2) as a binder is formed, and the styryl compound of the present invention is used as the charge transporting material. There is.

Figure 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) is provided with a charge generation layer (
6) and a charge transport layer (5), it may be of a functionally separated type.

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, polyvinyl butyral resin, casein, etc. may be used. The photoreceptor of this embodiment may also have a photosensitive layer of a functionally separated type.

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

Suitable solvents for use in this case include dichloromethane, dichloroethane, chloroform, trichloroethane, aliphatic hydrocarbons such as carbon tetrachloride, ketones such as cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, dioxane, tetrahydrofuran, dioxolane, 4-methyldioxolane, dimethyl A cyclic ether such as dioxane or a mixed solvent thereof. The styryl compound of the present invention has excellent solubility in the above-mentioned solvents and gives good results in coating properties and photosensitivity.

Furthermore, the styryl compound of the present invention has good compatibility with the binder resin, which results in good photosensitivity.

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,
Heplyocyanines such as aluminyl lophthalocyanine 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 μm or less, preferably 2 μm or less, and the thickness of the charge transport layer is 3 to 30 μm, preferably 5 to 20 μm. 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.

Charge-generating materials and dispersed photoconductive materials used in the functional separation of the photoreceptor of the present invention include bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthine dyes, and cyanine dyes. , styryl dyes, pyrylium dyes, azo pigments,
Quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments,
Organic substances such as induthrone pigments, squarylium pigments, phthalocyanine pigments, selenium, selenium/tellurium,
Examples include inorganic substances such as 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.

Moreover, the binder that can be used is electrically insulating, 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-enyl 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 1X10''Ω·0111 or more when measured alone.More preferred are polyester resin, polycarbonate, and acrylic resin.

The photoreceptor of the present invention contains /X rogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene,
Plasticizers such as dibutyl phthalate and 0-terphenyl, chloranil, tetracyanoethylene, 2.4.7-)
Electron-withdrawing sensitizers such as dinitro-9-fluorenone, 5,6-dicyazbenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3,5-dinitrobenzoic acid, methyl violet, rhodamine B1 cyanine dye, pyrylium Sensitizers such as salts, thiapyrylium salts, etc. may also be used.

The photoreceptor formed in this manner may have an adhesive layer, an intermediate layer, and a surface protection layer as required, as shown in FIGS. 4 and 5 described above.

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.

Further, the thickness of the intermediate layer is preferably 1 pffl 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 halogen, atoms of Group Ⅰ and Group V 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 [51) 2.82 g of a phosphonate represented by the following formula; and 2.79 g of an aldehyde compound represented by the following formula were dissolved in 30 mQ of dimethylformamide, and while heating to 30 to 40°C, In 60 mQ of dimethylformamide, potassium-ter-
A suspension containing 5 g of butoxide was added dropwise. Thereafter, the mixture was stirred at room temperature for 8 hours and then left overnight. The obtained mixture was added to 900 z12 of ice water, mixed with dilute hydrochloric acid, and after about 30 minutes, the precipitated crystals were filtered off. The filtered product was washed with water and recrystallized using acetonitrile to obtain 3.6 g of yellow needle crystals. (Yield 91%) Elemental analysis is as follows.

Example 1 0.45 parts of a disazo compound represented by the following formula (Δ) 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.

Thickness of the resulting disazo compound dispersion! Using a film applicator on 00μ- aluminized mylar,
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.

Using a commercially available electrophotographic copying machine (EP-4702 manufactured by Minolta Camera Co., Ltd.), the photoreceptor thus obtained was
The initial surface potential is V. (V), the exposure amount El/2 (lux-
8ec), and the decay rate D D Rl (%) of the initial potential was measured when the sample was left in the dark for 1 second.

Examples 2 to 4 Same structure as in Example 1, except that styryl compounds [3], [4], and [5] were used in place of styryl compound [2] used in Example 1. A photoreceptor was produced.

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

Example 5 0.45 parts of a disazo compound represented by the following 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 dispersion of the disazo compound obtained was applied onto a 100 μm thick aluminized mylar using a film applicator so that the dry film thickness was 0.3 g/m, and then dried. 70 parts of styryl compound [7] and polyarylate resin (U-100; manufactured by Unitika Co., Ltd.) 7 were placed on the charge generation layer obtained in
A solution prepared by dissolving 0 part 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 manner, an electrophotographic photoreceptor having a two-layer photosensitive layer was produced.

Examples 6 to 8 Same structure as in Example 5, except that styryl compounds [8], [11], and [12] were used in place of styryl compound [7] used in Example 5. A photoreceptor was produced.

Regarding the photoreceptor thus obtained, vo, El/2, and DDR were measured in the same manner as in Example 1.

Example 9 50 parts of copper phthalocyanine and 0.2 parts of tetranitro copper phthalocyanine were dissolved in 500 parts of 98% concentrated sulfuric acid with sufficient stirring, and this was poured into 5000 parts of water to dissolve copper phthalocyanine and tetranitro copper phthalocyanine! After precipitating the photoconductive material composition of 7-lycyanine, it was filtered, washed with water, and heated at 120°C under reduced pressure.
It was dried.

10 parts of the photoconductive composition thus obtained was added to a thermosetting acrylic resin (Acrydike A405; Dainippon Ink Co., Ltd.).
) 22.5 parts, melamine resin (Super Beckamine J
820 (manufactured by Dainippon Ink Co., Ltd.), 7.5 parts of the above-mentioned styryl compound [21115 parts] were placed in a ball mill pot with 100 parts of a mixed solvent containing equal amounts of methyl ethyl ketone and xylene, and exposed for 48 hours. A photoreceptor was prepared by preparing a photoreceptor coating liquid, which was applied onto an aluminum substrate, and dried to form a photosensitive layer having a thickness of about 15 μm.

The thus obtained photoreceptor was charged in the same manner as in Example 1, except that it was corona charged at +6 KV to give Vo, E1/
2. DDR was measured.

Examples 1O to 12 Photosensitization using the same method and the same structure as Example 9, except that styryl compounds [22], [24], and [291] were used in place of the styryl compound [21] used in Example 9. The body was created.

Regarding the photoreceptor thus obtained, vo, El/x, and DDR were measured in the same manner as in Example 9.

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.

With respect to the thus obtained photoreceptor, V was treated in the same manner as in Example 9. , E1/2, and DDR.

Comparative Examples 5 to 8 Same method and same structure as Example 9, except that the following styryl compounds (G), (H), (I), ( A photoreceptor was produced in exactly the same manner as in Example 9 except that each of J) was used.

With respect to the thus obtained photoreceptor, V was treated in the same manner as in Example 9. , E1/2, and DDR.

VO of the photoreceptors obtained in Examples 1-12 and Comparative Examples 1-8
, E1/2, DDR, (7) The measurement results are summarized in Table 1.

In addition, in Comparative Examples 1.2 and 5.7.8, crystals precipitated during the preparation of the photoreceptor due to poor solubility in solvents and resins.

(Hereinafter, blank space) Table 1 As can be seen from Table 1, the photoreceptor of the present invention has sufficient charge retention ability whether it is a laminated type or a single layer type, and the dark decay rate is also at a level that can be used as a photoreceptor. It is clear from the data that it is small in size and has excellent sensitivity.

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.

Effects of the Invention The photoreceptor of the present invention contains the above-mentioned styryl compound, has excellent charge transport properties, has a stable initial surface potential, has a sufficiently small dark decay rate, and has good charging properties. have 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 a photoreceptor according to the present invention, and FIGS. 1, 4, and 5 show a photoreceptor with a dispersion formed by laminating a photosensitive layer 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. 1... Conductive support 2... Charge transport material 3.
...Photoconductive material 4...Photosensitive layer 5...Charge transport layer 6...Photoconductive layer 7...Surface protection layer
8...Middle layer patent applicant Minolta Camera Co., Ltd.

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] [wherein R_1, R_2 each represents an alkyl group, an aralkyl group, or an aryl group which may have a substituent, R_1 and R_2 may be combined to form a ring, and R_1 or R_2 may be combined with Ar_1 to form a ring. may be formed. Ar_1 and Ar_2 each represent a divalent group of an aromatic monocyclic hydrocarbon or a condensed polycyclic hydrocarbon, which may have a substituent. Ar_3 represents a residue of an aromatic monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, or a heterocyclic compound. R_3 represents hydrogen, a hydroxyl group, an alkyl group, an aralkyl group, or an alkoxy group. n is 0
~ represents an integer of 3]