JPH06118665A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide a photosensitive body which has a high sensitivity and is useful for use in a high-speed printer, etc. by laminating a carrier generating'' layer and a carrier transfer layer on a conductive base and controlling the transmittance to specific monochromatic light of the carrier transfer layer. CONSTITUTION:The range of the transmittance of the carrier transfer layer 3 is <=90%. An effect is not obtainable at the transmittance above this range. The transmittance is, thereupon, lowered to <=90% by lowering 780nm light absorbance of the carrier transfer layer 3 in general as a means for limiting the transmittance. The incorporation of dyestuff having absorption in an IR region into the above-mentioned layer is equally satisfactory. Any dyestuff having absorption at 780nm is usable; more particularly, the naphthalocyanine compd. exhibits sharp absorption at about 780nm and has the excellent potential stability at the time of repetitive use and is, therefore, more preferable. As to the naphthalocyanine, the naphthalocyanines of various central metals are used as carrier generating material.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor,
The present invention relates to an electrophotographic photosensitive member which is useful for a printer, a copying machine, and the like, and which is also suitable when an image is formed by using a semiconductor laser beam or the like as an exposing unit.

[0002]

2. Description of the Related Art In recent years, photoconductive materials have been actively researched and applied to photoelectric conversion elements such as electrophotographic photoreceptors, solar cells and image sensors.
Conventionally, inorganic materials have been mainly used as these photoconductive materials. For example, in an electrophotographic photoreceptor, a photosensitive layer containing an inorganic photoconductive material such as selenium, zinc oxide, or cadmium sulfide as a main component is provided. Inorganic photoreceptors have been widely used.

However, such an inorganic photoconductor has not always been satisfactory in characteristics such as photosensitivity, thermal stability, moisture resistance and durability required for electrophotographic photoconductors of copying machines, printers and the like. For example, selenium is crystallized by heat, stains on fingerprints, etc., so that the characteristics as an electrophotographic photoreceptor are likely to deteriorate. Further, the electrophotographic photoreceptor using cadmium sulfide is inferior in moisture resistance and durability, and the electrophotographic photoreceptor using zinc oxide also has a problem in durability.

Further, in recent years, environmental problems have been particularly emphasized, but electrophotographic photoconductors such as selenium and cadmium sulfide have a drawback in that production and handling are largely restricted in view of toxicity.

In order to remedy the drawbacks of such inorganic photoconductive materials, various organic photoconductive materials have been attracting attention, and in recent years, attempts have been made to use them in the photosensitive layer of electrophotographic photoreceptors. Active research is being conducted. For example, Japanese Patent Publication No. 50-10496 describes an organic photoreceptor having a photosensitive layer containing polyvinylcarbazole and trinitrofluorenone. However, this photoreceptor is not sufficient in sensitivity and durability. Therefore, a function-separated electrophotographic photosensitive member has been developed in which different substances have different functions of carrier generation and carrier transport.

In such an electrophotographic photosensitive member, since a wide range of materials can be selected, it is easy to obtain arbitrary characteristics,
Therefore, it is expected that an organic photoreceptor having high sensitivity and high durability can be obtained.

Various organic compounds have been proposed as carrier-generating substances and carrier-transporting substances for such a function-separated type electrophotographic photosensitive member. In particular, the carrier-generating substance is important for controlling the basic characteristics of the photosensitive member. Has various functions. As carrier generating substances, photoconductive substances such as polycyclic quinone compounds typified by dibromoanthanthrone, pyrylium compounds and eutectic complexes of pyrylium compounds, squarylium compounds, phthalocyanine compounds, and azo compounds have been put to practical use. It was

Among them, it is known that titanyl phthalocyanine having a specific crystal form exhibits particularly excellent characteristics. Titanyl phthalocyanine has a large number of crystals and exhibits completely different performance depending on the crystal type. Among them, the crystal type having the maximum peak at 27.2 ° ± 0.2 ° of Bragg angle 2θ in the X-ray diffraction spectrum for Cu-Kα Since such titanyl phthalocyanine has a remarkably high photon efficiency, such a titanyl phthalocyanine has a remarkably high photon efficiency. It is also very useful for designing high speed facsimiles.

However, when such a compound having a high quantum efficiency is used as a carrier-generating substance, it has a high sensitivity and reacts even with a small amount of light. In this case, even a slight leak of light may be picked up as an image in the use environment and may be a defect. In addition, for example, when a semiconductor laser is used as the exposure means, it is expected that the reproducibility of fine lines will be affected when a large amount of light is irradiated on the photoconductor due to variations in irradiation light intensity.
Further, it is desired to arbitrarily adjust the light attenuation characteristics of the photoconductor according to the image forming process to be used, but in the conventional technique, the light attenuation characteristics can be changed to desired characteristics unless the carrier generating substance and the carrier transporting substance are changed. It was impossible to do. Further, by changing the combination of the carrier-generating substance and the carrier-transporting substance, not only the cost is increased, but also the stability of the photoreceptor during repeated use due to factors such as a difference in ionization potential may cause a problem. From these points, there is a demand for a technique for adapting an electrophotographic photosensitive member to various image forming processes by using a kind of photosensitive layer without impairing various characteristics required for the electrophotographic photosensitive member such as repetitive characteristics. .

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photosensitive member which overcomes the above problems and which has high sensitivity and is useful for a high speed printer, a high speed digital copying machine or a high speed facsimile.

Another object of the present invention is to obtain an electrophotographic photosensitive member having stable characteristics upon repeated use.

A further object of the present invention is to obtain an electrophotographic photosensitive member which is excellent in production stability, has less fluctuation in characteristics, and has excellent image characteristics.

[0013]

The above object of the present invention is to provide an electrophotographic photosensitive member comprising a carrier generating layer and a carrier transporting layer laminated on a conductive support, and to improve the transmittance of the carrier transporting layer for monochromatic light of 780 nm. It is achieved by controlling. The range of the transmittance of the carrier transport layer is 90% or less, and if the transmittance is higher than this range, the effect of the present invention cannot be obtained.

Various means can be considered as means for limiting the transmittance, but generally, the transmittance can be reduced to 90% or less by increasing the absorbance at 780 nm of the carrier transport layer. For example, it has absorption in the infrared region. The purpose can be achieved by incorporating a dye.

As the infrared absorbing dye used in the present invention,
Any dye having an absorption at 780 nm may be used, but a naphthalocyanine compound is particularly preferable because it exhibits a sharp absorption at around 780 nm and has excellent potential stability upon repeated use.

Regarding naphthalocyanine, naphthalocyanines of various central metals have already been used as carrier generating substances. However, in the photoreceptor of the present invention, the infrared absorbing naphthalocyanine does not have a function of contributing to the sensitivity due to generation of carriers, and is different in that the function is exhibited not in the carrier generation layer but in the carrier transport layer.

The naphthalocyanine used in the present invention is represented by the following general formula [2].

[0018]

[Chemical 2]

[Wherein M represents a hydrogen atom or a metal atom, and preferably Si, Ge, Sn, Cu, Zn, Mg, Ti,
V, Al, In, etc. may be mentioned. Y represents a substituted or unsubstituted alkyl group, an alkoxy group, an aryloxy group, a halogen atom, an oxygen atom, a siloxy group, or a hydroxyl group, and X ¹ , X ² , X ³ , and X ⁴ are a hydrogen atom, a halogen atom, It represents an alkyl group, an alkoxy group, or an aryloxy group. Moreover, k, 1, m, and n represent the integer of 0-4.

Further, the naphthalocyanine compound used in the present invention is preferably a naphthalocyanine having a high solubility in an organic solvent or various binders in order to be used in the form of being dissolved in a binder in the carrier transport layer. Those having an alkyl group with a large number of carbon atoms in the molecule have high solubility,
It is preferable to have an alkyl group having 6 or more carbon atoms.

Therefore, in the naphthalocyanine represented by the general formula [2], M, Y and X are specified, and the silicon naphthalocyanine represented by the general formula [1] shown in the above [Chemical formula 1] is particularly preferable. .

These silicon naphthalocyanines can be synthesized according to the method described in J. Am, Chem. Soc., 106, 7404 (1984).

Specific examples of silicon naphthalocyanine used in the present invention are shown below.

[0024]

[Chemical 3]

[0025]

[Chemical 4]

[0026]

[Chemical 5]

[0027]

[Chemical 6]

The carrier-generating substance used in the present invention may be any as long as it is sensitive to LD light. Specifically, it is a crystalline metal-free phthalocyanine such as α, β, τ and X, and A. , B, C crystals, amorphous and titanyl phthalocyanine having a maximum peak at 27.2 ° of Bragg angle 2θ, mixed crystals of plural phthalocyanines typified by mixed crystals of titanyl phthalocyanine and vanadyl phthalocyanine, copper phthalocyanine, etc. Various metal phthalocyanines, naphthalocyanines, and other porphyrin derivatives, azo compounds, polycyclic quinone compounds represented by dibromoanthanthrone, pyrylium compounds and eutectic complexes of pyrylium compounds, and squarylium compounds. Titanylph with maximum peak at 27.2 ° ± 0.2 of 2θ Roshianin is preferred,
Furthermore, Bragg angle 2θ (± 0.2 °) of 9.5 °, 24.1 °, 27.2
Most preferred is titanyl phthalocyanine having a peak at °.

The X-ray diffraction spectrum is measured under the following conditions, and the peak here is a protrusion having a sharp acute angle different from noise.

X-ray tube Cu voltage 40.0 KV current 100 mA start angle 6.0 deg. Stop angle 35.0 deg. Step angle 0.02 deg. Measurement time 0.50 sec. The electrophotographic photosensitive member of the present invention may use the above carrier-generating substance in combination.

Next, various carriers can be used as the carrier transporting material used in the electrophotographic photosensitive member of the present invention. Typical examples thereof include oxazole, oxadiazole, thiazole, thiadiazole and imidazole. Compounds having a nitrogen-containing heterocyclic nucleus and condensed ring nuclei thereof, polyarylalkane compounds, pyrazoline compounds, hydrazone compounds, triarylamine compounds, styryl compounds, poly (bis) styryl compounds, styryltriphenyl Examples thereof include amine compounds, β-phenylstyrylphenylamine compounds, butadiene compounds, hexatriene compounds, carbazole compounds, condensed polycyclic compounds and the like. Specific examples of these carrier-transporting substances include the carrier-transporting substances described in JP-A-61-107356. The structures of particularly representative ones are shown below.

[0032]

[Chemical 7]

[0033]

[Chemical 8]

[0034]

[Chemical 9]

[0035]

[Chemical 10]

[0036]

[Chemical 11]

Various forms of the photoreceptor are known. The photoreceptor of the present invention is preferably a laminated type function separation type photoreceptor. In this case, the configuration is usually as shown in FIGS. The layer structure shown in (1) has a conductive support 1
A carrier generating layer 2 is formed on the carrier generating layer 2, and a carrier transporting layer 3 is laminated on the carrier generating layer 2 to form a photosensitive layer 4. (2) is a semi-transparent conductive support 1'on which the carrier generating layer 2 is formed. A photosensitive layer 4'in which the carrier transport layer 3 is reversed is formed. This is a layer structure when light is irradiated from the conductive support side. In (3), the intermediate layer 5 is provided between the photosensitive layer 4 having the layer structure of (1) and the conductive support 1. In the configurations (1) to (4), a protective layer may be further provided on the outermost layer.

In forming the photosensitive layer, it is effective to apply a solution in which the carrier-generating substance or the carrier-transporting substance is dissolved alone or together with a binder or an additive. However, since the solubility of the carrier-generating substance is generally low, in such a case, the carrier-generating substance is treated with an ultrasonic disperser,
A method of applying a liquid in which fine particles are dispersed in an appropriate dispersion medium using a dispersing device such as a ball mill, a sand mill, a homomixer, etc. is effective. In this case, the binder and additives are usually used by adding them to the dispersion liquid.

A wide variety of solvents or dispersion media can be used as the solvent or dispersion medium for forming the photosensitive layer. For example, butylamine, ethylenediamine, N, N-dimethylformamide, acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, cyclohexanone, 4-methoxy-4-methyl-2-pentanone, tetrahydrofuran, dioxane, ethyl acetate, butyl acetate,
Acetic acid-t-butyl, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethylene glycol dimethyl ether, toluene, xylene, acetophenone, chloroform, dichloromethane, dichloroethane, trichloroethane, methanol, ethanol, propanol, butanol and the like can be mentioned.

When a binder is used for forming the carrier generating layer or the carrier transporting layer, any binder can be selected, but a high molecular polymer having hydrophobicity and film forming ability is particularly desirable. Examples of such a polymer include the following,
It is not limited to these. Polycarbonate Polycarbonate Z Resin Acrylic Resin Methacrylic Resin Polyvinyl Chloride Polyvinylidene Chloride Polystyrene Styrene-Butadiene Copolymer Polyvinyl Acetate Polyvinyl Formal Polyvinyl Butyral Polyvinyl Acetal Polyvinylcarbazole Styrene-Alkyd Resin Silicone Resin Silicone-Alkyd Resin Silicone-Butylal Resin Polyester Polyurethane Polyamide Polyurethane Epoxy Resin Phenolic resin Vinylidene chloride-Acrylonitrile copolymer Vinyl chloride-Vinyl acetate copolymer Vinyl chloride-Vinyl acetate-Maleic anhydride copolymer The ratio of the carrier generating substance to the binder is preferably 10 to 600% by weight, and further 50 It is desirable to set it to 400% by weight. The ratio of carrier transport material to binder
It is desirable to be 10 to 500% by weight. Further, the ratio of the infrared absorbing dye to the binder is 0.0001 to 10% by weight, particularly preferably 0.001% to 1% by weight. The thickness of the carrier generation layer is 0.01 to 20 μm, and further 0.0
5 to 5 μm is preferable. The thickness of the carrier transport layer is 1-100μ
m, but more preferably 5 to 30 μm.

The photosensitive layer may contain an electron accepting substance for the purpose of improving sensitivity, reducing residual potential, or reducing fatigue during repeated use. Examples of such an electron accepting substance include succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride and 4-nitrophthalic anhydride. Acid, pyromellitic dianhydride, mellitic dianhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, 1,3,5-trinitrobenzene, p-nitrobenzonitrile, picryl chloride, Quinone chlorimide, chloranil, bromanil, dichlorodicyano-p-benzoquinone, anthraquinone, dinitroanthraquinone, 9-fluorenylidene malononitrile, polynitro-9-fluorenylidene malononitrile, picric acid, o-nitrobenzoic acid, p- Nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic acid Acid, 5-nitro salicylic acid, 3,5-dinitrosalicylic acid, phthalic acid, mellitic acid, and larger compounds of other electron affinity. The addition ratio of the electron accepting substance is 0.0 with respect to 100 by weight of the carrier generating substance.
It is preferably 1 to 200, more preferably 0.1 to 100.

Further, the above-mentioned photosensitive layer contains storability, durability,
For the purpose of improving the resistance to the environment, a deterioration inhibitor such as an antioxidant or a light stabilizer can be contained. Examples of compounds used for such purpose include chromanol derivatives such as tocopherol and its etherified or esterified compounds, polyarylalkane compounds,
Hydroquinone derivatives and mono- and dietherified compounds thereof, benzophenone derivatives, benzotriazole derivatives, thioether compounds, phosphonic acid esters, phosphorous acid esters, phenylenediamine derivatives, phenol compounds, hindered phenol compounds, linear amine compounds,
Cyclic amine compounds and hindered amine compounds are effective. Specific examples of particularly effective compounds include "IRGANOX
"1010", "IRGANOX 565" (manufactured by Ciba-Geigy), "Sumilyzer BHT", "Sumilyzer MDP" (manufactured by Sumitomo Chemical Co., Ltd.)
Hindered phenolic compounds such as "Sanol LS-262
6 ”,“ Sanol LS-622LD ”(manufactured by Sankyo Co., Ltd.) and the like.

As the binder used for the intermediate layer, the protective layer and the like, those mentioned above for the carrier generating layer and the carrier transporting layer can be used, but in addition to them, nylon resin, ethylene-vinyl acetate copolymer, Ethylene resins such as ethylene-vinyl acetate-maleic anhydride copolymer and ethylene-vinyl acetate-methacrylic acid copolymer, polyvinyl alcohol, and cellulose derivatives are effective.
Further, a curable binder utilizing heat curing or chemical curing of melamine, epoxy, isocyanate or the like can be used.

As the conductive support, a metal plate or a metal drum may be used, and a conductive polymer, a conductive compound such as indium oxide, or a thin layer of a metal such as aluminum or palladium may be applied, vapor deposited, laminated or the like. Therefore, the one provided on a substrate such as paper or plastic film can be used.

[0045]

EXAMPLES The present invention will be described in detail with reference to examples.

Examples 1 to 7 100 parts by weight of methyl ethyl ketone and 1 part by weight of polyvinyl butyral resin were added to 1 part by weight of titanyl phthalocyanine having peaks at 9.5 °, 24.1 ° and 27.2 ° of Bragg angle 2θ in FIG. 2 and a ball mill was used. Dispersed. After a part of the obtained dispersion liquid was evaporated to dryness, the X-ray diffraction spectrum was measured and it was as shown in FIG.

On the other hand, an undercoating layer of 0.3 μm in thickness made of polyamide resin “CM-8000” (manufactured by Toray Industries, Inc.) was provided on a polyester base on which aluminum was vapor-deposited by a wire bar coating method, and then the obtained dispersion Was applied to a wire bar to form a carrier generation layer having a thickness of 0.2 μm. Next, 1 part by weight of carrier transport material (21) and 1.33 parts by weight of polycarbonate resin "Iupilon Z-200" (manufactured by Mitsubishi Gas Chemical Co., Inc.) Silicon naphthalocyanine (2) and a small amount of silicone oil "KF-54" (manufactured by Shin-Etsu Chemical Co., Ltd.) ) Was dissolved in 8 parts by weight of 1,2-dichloroethane and blade-coated to a thickness of 20 μm.
Was formed into a carrier transport layer. The photoconductors thus obtained are referred to as Samples 1 to 7.

Example 8 A photoconductor was prepared in the same manner as in Example 6 except that silicon naphthalocyanine (1) was used instead of silicon naphthalocyanine (2). This is sample 8.

Example 9 A photoreceptor of the present invention was obtained in the same manner as in Example 6 except that a silicone resin was used instead of the polyvinyl butyral resin in Example 6. This is sample 9.

Example 10 A photoreceptor of the present invention was obtained in the same manner as in Example 6 except that a silicone-butyral resin was used instead of the polyvinyl butyral resin in Example 6. This is sample 10.

Example 11 Dispersion liquid 1,4-butanediol 1 obtained in Example 6
A photoconductor was prepared in the same manner as in Example 6 except that parts by weight were added. This is sample 11.

Example 12 A photoconductor of the present invention was obtained in the same manner as in Example 11 except that cyclohexanone was used in place of methyl ethyl ketone and polycarbonate Z resin was used in place of polyvinyl butyral resin. This is sample 12.

Comparative Example (1) A comparative photoconductor was obtained in the same manner as in Example 6 except that silicon naphthalocyanine was omitted from Example 6. These are designated as comparative sample (1).

Comparative Examples (2) to (5) Comparative photoconductors were obtained in the same manner as in Examples 9 to 12 except that silicon naphthalocyanine was omitted from Examples 9 to 12.
These are designated as Comparative Samples (2) to (5). Evaluation 1 The transmittance T (%) of the 20 μm carrier transport layer of the obtained sample for 780 nm light was measured.

Evaluation 2 The obtained sample was subjected to “KONI” under the environment of 20 ° C. and 50% RH.
CA 9028 "(made by Konica Corporation, using a semiconductor laser light source) is installed on a modified machine, the grid voltage V _G is adjusted to 600 V, and the unexposed part potential V _H and the exposed part potential V _L at the time of light irradiation of 0.7 mW are set. It was measured. Then, the sample was transferred to an environment of 10 ° C. and 20% RH and sufficiently adapted to the environment, and then V _H and V _L were measured under the above-mentioned conditions. In addition, V _H and V _L after repeated use of 10,000 prints in an environment of 10 ° C. and 20% RH were also measured.

Evaluation 3 The sample was also left in an atmosphere of 55 ° C. and 80% RH for 1 week, then mounted on a modified “KONIKA 9028” under the environment of 20 ° C. and 50% RH, and V _H and V _L It was measured.

The evaluation results are shown in Table 1. The photoconductor of the present invention shows remarkable effects on fluctuations in humidity, reduction in changes in photoconductor characteristics due to repeated use, stabilization of dispersion liquid and photoconductor, and depending on the amount of infrared absorbing dye used It is possible to obtain a photosensitive member having sensitivity.

[0058]

[Table 1]

Example 13 The same as Example 1 except that the titanyl phthalocyanine in Example 6 was replaced with titanyl phthalocyanine showing an X-ray diffraction spectrum having peaks at Bragg angles 2θ of 27.2 °, 24.1 ° and 9.0 °. The photoconductor of the present invention was obtained. This is sample 13.

Comparative Example (6) A photoconductor of the present invention was obtained in the same manner as in Example 13 except that the silicon naphthalocyanine in the present invention was omitted. This is designated as Comparative Sample (6).

Sample 13 and comparative sample (6) were evaluated according to the methods of Evaluations 1 and 2. The results are shown in Table 2.

[0062]

[Table 2]

It is confirmed that the system of the present invention exhibits excellent properties.

[0064]

According to the constitution of the present invention, the light attenuation characteristic can be adjusted to a desired characteristic without changing the carrier generating substance and the carrier transporting substance and without impairing the various properties required for the electrophotographic photosensitive member. It has become possible. Further, the electrophotographic photoreceptor of the present invention is stable under various environments and can greatly improve the potential stability upon repeated use.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrophotographic photosensitive member of the present invention.

2 is an X-ray diffraction spectrum diagram of the titanyl phthalocyanine used in Example 1. FIG.

FIG. 3 X after evaporation of the dispersion to dryness in Example 1
Line diffraction spectrum diagram.

FIG. 4 is an X-ray diffraction spectrum diagram of the titanyl phthalocyanine used in Example 13.

[Explanation of symbols]

 1, 1'conductive support 2 carrier generation layer 3 carrier transport layer 4, 4'photosensitive layer 5 intermediate layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihide Fujimaki 2970 Ishikawacho, Hachioji City, Tokyo Konica Stock Company

Claims (6)

[Claims] 1. An electrophotographic photoreceptor comprising a carrier generating layer and a carrier transporting layer laminated on a conductive support, wherein the carrier transporting layer has a transmittance of 90% for monochromatic light of 780 nm.
An electrophotographic photoreceptor characterized by the following: 2. The electrophotographic photosensitive member according to claim 1, wherein the carrier transport layer contains an infrared absorbing dye. 3. The electrophotographic photosensitive member according to claim 2, wherein the infrared absorbing dye is naphthalocyanine. 4. The electrophotographic photosensitive member according to claim 3, wherein the naphthalocyanine is silicon naphthalocyanine represented by the following general formula [1]. [Chemical 1] [In the formula, Y represents a (Rn) ₃ SiO— group (Rn represents an alkyl group or an aryl group, and at least one of Rn is an alkyl group having 6 or more carbon atoms), and X ¹ , X ² , X ³ , X ⁴ is a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group,
Represents an aryloxy group. Also, k, l, m and n are 0 to 4
Represents the integer. ] 5. The electrophotographic photosensitive member according to claim 1, which contains phthalocyanine as a carrier generating substance. 6. The titanyl phthalocyanine having a maximum peak at 27.2 ° of Bragg angle 2θ with respect to Cu-Kα ray (wavelength 1.541Å) is contained as a carrier generating substance. Electrophotographic photoreceptor.