JPH0827542B2 - Photoconductor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a photoreceptor containing a low molecular weight organic compound.

2. Description of the Related Art Generally, in electrophotography, the surface of a photosensitive layer of a photoconductor is charged and exposed to form an electrostatic latent image, which is developed with a developer to be visualized. Direct method of fixing on top to obtain a copy image, or powder image transfer method of transferring a visible image on a photoreceptor onto a transfer paper such as paper and fixing the transferred image to obtain a copy image or on a photoreceptor There is known a latent image transfer system in which an electrostatic latent image is transferred onto a transfer paper, and the electrostatic latent image on the transfer paper is developed and fixed.

Conventionally, it has been known to use an inorganic photoconductive material such as selenium, cadmium sulfide, or zinc oxide as a photoconductive material for forming a photosensitive layer of a photoconductor used in this type of electrophotography. . While these photoconductive materials have many advantages, such as being able to be charged to an appropriate potential in a dark place, having little charge dissipation in a dark place, or being able to quickly dissipate charge by light irradiation, It has various disadvantages as follows. For example, with selenium-based photoreceptors,
Manufacturing costs are high, and it is sensitive to heat and mechanical shock, so care must be taken.In addition, cadmium sulfide-based photoconductors and zinc oxide photoconductors do not provide stable sensitivity in humid environments. The dye added as a sensitizer has a drawback that stable characteristics cannot be provided over a long period of time because charge deterioration due to corona charging and photobleaching due to exposure occur.

On the other hand, various organic photoconductive polymers such as polyvinylcarbazole have been proposed, but these polymers are superior in film forming property and lightness to the above-mentioned inorganic photoconductive materials. However, it is still inferior to inorganic photoconductive materials in terms of sufficient sensitivity, durability and stability due to environmental changes.

A low molecular weight organic photoconductive compound is preferable in that the physical properties or electrophotographic properties of the coating film can be controlled by selecting the type and composition ratio of the binder used in combination. Since it is used in combination with a binder, high compatibility with the binder is required.

The photoconductor in which these high-molecular weight and low-molecular weight organic photoconductive compounds are dispersed in the binder resin has drawbacks such as a large residual potential because of many carrier traps and low sensitivity. Therefore, it has been proposed to blend an organic photoconductive compound with a charge transport material to solve the above drawbacks.

Although many organic compounds are mentioned as charge transport materials, there are various problems in practice. US Patent No.
The 2,5-bis (P-diethylaminophenyl) -1,3,4-oxadiazole described in 3,189,447 is
The compatibility with the binder is low and crystals tend to precipitate. The diarylalkane derivative described in U.S. Pat. No. 3,820,989 has good compatibility with a binder, but changes sensitivity when used repeatedly. Further, the hydrazone compounds described in JP-A-54-59143 have relatively good residual potential characteristics, but have the drawbacks of poor sensitivity, chargeability and repetitive characteristics.

As described above, there are almost no low-molecular-weight organic compounds having practically preferable properties for producing a photoreceptor.

An object of the present invention is to include an enamine compound having excellent compatibility with a binder and excellent charge transporting ability, high sensitivity and excellent charging ability, less fatigue deterioration due to repeated use, and stable electrophotographic characteristics. Intended to provide the body.

Means for Solving the Problems The present invention solves the above-mentioned drawbacks by containing a specific enamine compound.

The gist of the present invention is a photoconductor characterized by containing an enamine compound represented by the following general formula.

General formula [In the formula, R1 represents hydrogen, an alkyl group, an alkoxy group, a phenoxy group, an aroxy group or a di-substituted amino group. R2 represents hydrogen or an aryl group, and the aryl group may have a substituent. R3 is an alkyl group, R4 is hydrogen, an alkyl group,
An alkoxy group and a di-substituted amino group are shown. n shows the integer of 1-3.

However, R1 and R2 do not take hydrogen at the same time. The preferred specific examples of the enamine compound represented by the general formula [I] of the present invention include, but are not limited to, those having the following structural formulas.

The enamine compound represented by the general formula [I] of the present invention can be easily produced by a known method.

For example, the following general formula [II] general formula: [Wherein R ₁ , R ₂ and n have the same meaning as in [I]] and the following general formula [III]: [Wherein R ₃ and R ₄ have the same meaning as in [I]] can be synthesized by subjecting an amine compound represented by the formula to a dehydration condensation reaction.

In the reaction, water produced by using a solvent such as benzene, toluene, or xylene is generally removed by azeotropic distillation, potassium carbonate, P-toluenesulfonic acid, or acetic acid Dowe.
x50, or with a catalyst such as Montmorillonite catalyst KIO.

A structural example of a photoconductor using the enamine compound of the present invention is schematically shown in FIGS. 1 to 5.

FIG. 1 shows a photoreceptor in which a photoconductive layer (4) in which a photoconductive material (3) and a charge transport material (2) are mixed with a binder is formed on a substrate (1). The enamine compound of the present invention is used.

FIG. 2 shows a function-separated type photoreceptor having a charge generation layer (6) and a charge transport layer (5) as a photosensitive layer. The charge transport layer (5) is formed on the surface of the charge generation layer (6). There is. The enamine compound of the present invention is blended in the charge transport layer (5).

Similar to FIG. 2, FIG. 3 shows a function-separated type photoreceptor having a charge generation layer (6) and a charge transport layer (5). On the contrary to FIG. A charge generation layer is formed.

FIG. 4 shows the surface of the photoreceptor of FIG. 1 further provided with a surface protective layer (7). The photosensitive layer (4) is separated into a charge generation layer (6) and a charge transport layer (5). It may be a function separation type.

FIG. 5 shows an intermediate layer (8) provided between the substrate (1) and the photosensitive layer (4). The intermediate layer (8) has improved adhesion, improved coatability, and substrate protection. , Can be provided to improve the charge injection property from the substrate to the photoconductive layer. As the intermediate layer, a polyimide resin, a polyester resin, a polyvinyl tylal resin, casein, or the like may be used. In the photoreceptor of this aspect, the photosensitive layer may have a function-separated type.

The photoreceptor of the present invention is prepared by dissolving or dispersing an enamine compound represented by the general formula [I] in a suitable solvent together with a binder, and if necessary, a photoconductive material and an electron-withdrawing compound, or a sensitizing dye, other The coating solution obtained by adding the pigment is coated on a conductive substrate and dried, usually 5 to 30μ
m, preferably from 6 to 20 μm.

The photosensitive layer is formed by laminating a photosensitive layer on a conductive support.
A dispersion type photoreceptor having the same structure as the photoreceptor shown in the figure is obtained by dispersing fine particles of a photoconductive material in a solution in which an enamine compound and a resin are dissolved, coating this on a conductive support and drying it. Obtained by forming layers. At this time, the thickness of the photosensitive layer is 3 to 30 μm, preferably 5 to 20 μm. If the amount of the photoconductive material used is too small, the sensitivity is poor, and if it is too large, the charging property is deteriorated or the strength of the photosensitive layer is weakened. 0.01 to 2 parts by weight, preferably 0.05 to 1 part by weight, is preferable, and the ratio of the enamine compound is 0.01 to 1 part by weight of the resin.
˜2 parts by weight, preferably 0.02 to 1.2 parts by weight. It may also be used in combination with a polymer photoconductor such as polyvinyl carbazole which itself can be used as a binder. It may also be combined with other charge transport materials such as hydrazone compounds.

Specifically, a function-separated type photoreceptor having the same structure as that shown in FIG. 2 which is obtained by stacking a charge generation layer and a charge transport layer on a conductive support has a photoconductive material on the conductive support. Vacuum evaporation, or an appropriate solvent or, if necessary, dispersed in a solution in which a binder resin is dissolved, is applied and dried to form a charge generating layer, on which an enamine compound and a binder are formed. It is obtained by applying a solution in which is dissolved in a suitable solvent and drying it to form a charge transport layer. At this time, the thickness of the charge generation layer is 4 μm or less, preferably 2 μm.
The thickness of the charge transport layer is 3 to 30 μm, preferably 5 to 20 μm. The proportion of the enamine compound in the charge transport layer is 0.02 to 2 parts by weight, preferably 0.03 to 1.3 parts by weight, based on 1 part by weight of the binder. Also,
Other charge transport materials may be combined. In the case of the polymer charge transport material which itself can be used as a binder, other binder may not be used. The photoreceptor may have a configuration in which a charge transport layer is formed on a conductive support and a charge generation layer is laminated thereon similarly to the photoreceptor of FIG.

Examples of materials used for the photoconductive material of the photoreceptor of the present invention include bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes,
Cyanine dye, styryl dye, pyrylium dye,
Organic substances such as azo pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indathlon pigments, squarylium pigments, phthalocyanine pigments, selenium, selenium tellurium Inorganic substances such as selenium / arsenic, cadmium sulfide, and amorphous silicon are listed. Other than this,
Any material can be used as long as it absorbs light and generates charge carriers with extremely high efficiency.

What can be used as a binder in the present invention,
Any known electrically insulating thermoplastic resin, thermosetting resin, photocurable resin, or photoconductive resin may be used.

Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins,
Acrylic resin, ethylene-vinyl acetate copolymer, ion-crosslinked olefin copolymer (ionomer), styrene-
Thermoplastic binders such as butadiene block copolymer, polyarylate, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide, styrene resin; epoxy resin, urethane resin, silicone resin, phenol resin, melamine resin, Thermosetting binders such as xylene resin, alkyd resin, and thermosetting acrylic resin; photocurable resins; photoconductive resins such as poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene and the like. These can be used alone or in combination.

These electrically insulating resins are individually measured to be 1 × 10 ¹² Ω ・
It is desirable to have a volume resistance of cm or more. More preferred are polyester resins, polycarbonates,
Acrylic resin.

The photoreceptor of the present invention, together with a binder, halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene,
Plasticizers such as dibutyl phthalate, 0-ta-phenyl, chloranil, tetracyanoethylene, 2,4,7-trinitro-9-fluorenone, 5,6-dicyanobenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, An electron-withdrawing sensitizer such as 3,5-dinitrobenzoic acid,
A sensitizer such as methyl violet, rhodamine B, cyanine dye, pyrylium salt and thiapyrylium salt may be used.

The photoreceptor thus formed may have an adhesive layer, an intermediate layer (8) and a surface protective layer (7) as required as shown in FIGS. 4 and 5 described above.

EFFECT OF THE INVENTION The photoreceptor of the present invention contains the above-mentioned enamine compound, and thus has excellent charge transportability, stable initial surface potential, sufficiently low dark decay rate, and good chargeability. Have. In addition, there are few carrier traps and high sensitivity.

Example 1 1 part by weight of E-type copper phthalocyanine (manufactured by Toyo Ink Co., Ltd.), polyester resin (manufactured by Byron 200 Toyobo Co., Ltd.)
1 part by weight and 50 parts by weight of tetrahydrofuran were placed in a ball mill pot and dispersed for 24 hours to obtain a photosensitive coating solution. This was applied onto an aluminum substrate and dried to form a charge generation layer having a thickness of 1 μm.

On the charge generation layer, the enamine compound (3) described above is added.
10 parts by weight of polycarbonate resin (Panlite K1300, manufactured by Teijin Kasei Co., Ltd.) was dissolved in a solvent consisting of 100 parts by weight of tetrahydrofuran, and the coating liquid was applied and dried to form a charge transport layer with a thickness of 15μ. Then, a photoconductor was prepared.

Principal thus obtained photosensitive member using a commercially available electrophotographic copying machine (manufactured by Minolta Camera (Co.) EP450Z), was corona charged at -6 KV, the initial potential Vo (v), the initial potential to the _1/2 the exposure amount _{E 1/2 (lux · sec} ), attenuation rate DDR ₅ (%) of the initial potential when allowed to stand at 5 seconds dark was measured.

Examples 2 to 4 have the same constitution as in Example 1 except that the enamine processed products (4), (5) and (9) were used instead of the enamine compound (3) used in Example 1, respectively. A photoconductor to be used was prepared.

The thus obtained photosensitive member was measured Vo, the E _1/2, DDR ₅ in the same manner as in Example 1.

Example 5 50 parts by weight of copper phthalocyanine and 0.2 parts by weight of tetranitrocopper phthalocyanine were dissolved in 500 parts by weight of 98% concentrated sulfuric acid with sufficient stirring, and this was poured into 5,000 parts by weight of water to obtain photoconductivity of copper phthalocyanine and tetranitrocopper phthalocyanine. After depositing the material composition, it was filtered, washed with water, and dried at 120 ° C. under reduced pressure.

10 parts by weight of the photoconductive composition thus obtained was used as a thermosetting acrylic resin (Acridic A405 Dainippon Ink and Chemicals, Inc.)
22.5 parts by weight, melamine resin (Super Beckamine J8)
20 Dainippon Ink Co., Ltd. 7.5 parts by weight 15 parts by weight of the above-mentioned enamine compound (11) are put in a ball mill pot together with 100 parts by weight of a mixed solvent of methyl ethyl ketone and xylene in the same amount, and dispersed for 48 hours for photoconductivity. A photosensitive coating liquid was prepared, and the coating liquid was applied onto an aluminum substrate and dried to form a photosensitive layer having a thickness of about 15 μm to prepare a photoconductor.

The same method as in Example 1 thus obtained photosensitive member, except that measured Vo, the E _1/2, DDR ₅ performs corona charging at + 6KV.

Examples 6 to 8 having the same constitution as in Example 5, except that the enamine compounds (12), (13) and (14) were used instead of the enamine compound (11) used in Example 5, respectively. Was prepared.

Vo, the E _1/2, DDR ₅ was measured in the same manner as in Example 5 for thus obtained photosensitive member.

Example 9 2 parts by weight of a disazo face represented by the following general formula [A], a polyester resin (manufactured by Byron 200 Toyobo Co., Ltd.)
1 part by weight and 100 parts by weight of methyl ethyl ketone were placed in a ball mill pot and dispersed for 24 hours to obtain a photosensitive coating solution. This was applied onto an aluminum substrate and dried to form a charge generation layer having a thickness of 1 μm.

General formula: On the charge generation layer, the enamine compound (18) described above was added.
10 parts by weight, polyarylate resin (U-100 Unitika) 1
A coating liquid dissolved in a solvent consisting of 0 part by weight and 100 parts by weight of chlorobenzene was applied and dried to form a charge transport layer having a thickness of 15 μm, and a photoconductor was prepared.

Vo, the E _1/2, DDR ₅ was measured in the same manner as in Example 1 for the thus obtained photosensitive member.

Examples 10 to 11 Photoreceptors having the same constitution as in Example 9 but using the enamine compounds (20) and (21) instead of the enamine compound (18) used in Example 9 were prepared. did.

Vo, the E _1/2, DDR ₅ was measured in the same manner as in Example 1 was thus prepared photosensitive member.

Shows Vo obtained photoreceptor in Example 1 to 11, the measurement results of the E _1/2, DDR ₅ are summarized in Table 1.

As can be seen from Table 1, the photoconductor of the present invention has a stable initial surface potential of 600 V or more, and the dark decay rate is small enough to be used as a photoconductor and has good charging ability. . Also it can be seen that E _1/2 is also a small sensitive. Furthermore, an electrophotographic copying machine (EP35 manufactured by Minolta Camera Co., Ltd.)
Repetitive real-photographing test of positive charging with 0Z) was conducted on the photoconductors of Examples 5 and 6, and even after copying 10,000 sheets, excellent gradation was obtained in both initial and final images, and clear images were obtained without sensitivity change. The repeatability is stable.

[Brief description of drawings]

1 to 5 are schematic views of a photosensitive member according to the present invention, and FIGS. 1, 4, and 5 show a dispersion type photosensitive member obtained by laminating a photosensitive layer on a conductive support. The structure is shown in FIGS. 2 and 3 which shows the structure of a function-separated type photoreceptor in which a charge generation layer and a charge transport layer are laminated on a conductive support. DESCRIPTION OF SYMBOLS 1 ... Conductive support, 2 ... Charge transport material 3 ... Photoconductive material, 4 ... Photosensitive layer 5 ... Charge transport layer, 6 ... Photoconductive layer 7 ... Surface protective layer, 8 ... Middle class

Claims (1)

[Claims] 1. A photoconductor containing an enamine compound represented by the following general formula. General formula [In the formula, R1 represents hydrogen, an alkyl group, an alkoxy group, a phenoxy group, an aroxy group or a di-substituted amino group. R2 represents hydrogen or an aryl group, and the aryl group may have a substituent. R3 is an alkyl group, R4 is hydrogen, an alkyl group,
An alkoxy group and a di-substituted amino group are shown. n shows the integer of 1-3. However, R1 and R2 do not take hydrogen at the same time. ]