JPH06118676A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body which has excellent sensitivity characteristics and is useful for a high-speed printer, high-speed digital copying machine or high-speed facsimile, the electrophotographic sensitive body which is less changed in the sensitivity characteristics with a fluctuation in humidity and the electrophotographic sensitive body which has the stable characteristics at the time of repetitive use. CONSTITUTION:This electrophotographic sensitive body contains titanyl phthalocyanine of a crystal type having the max. peak at 27.2+0.2 deg. of a Bragg angle 2theta in X-ray diffraction spectra with Cu-Kalpha rays and contains a heterocyclic compd. having a hydroxyl group as a substituent in a 0.1 to 1000 pts.wt. range per 100 pts.wt. titanyl phthalocyanine.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor,
In particular, titanyl phthalocyanine having a specific crystal type is used as a photoconductive material, it is effective for a printer, a copying machine and the like, and is also suitable when an image is formed by using a semiconductor laser light and an LED light as an exposing means. Electrophotographic photoconductor.

[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 shows completely different performance depending on the crystal type, but 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 titanyl phthalocyanine has remarkably high photon efficiency, an electrophotographic photoreceptor using such titanyl phthalocyanine as a carrier generating material is extremely useful for designing high speed printers, high speed digital copying machines and high speed facsimiles. ing.

Fujimaki reported that in the X-ray diffraction spectrum 27.3
It was found that the Y-type titanyl phthalocyanine having very high photon efficiency, which has characteristic peaks at ° and 9.6 °, has a reduced photon efficiency when heated or dehydrated by a dry nitrogen atmosphere. This is because the photon efficiency is restored again when water is reabsorbed in a room temperature and normal humidity environment. Therefore, the Y-type crystal is a crystal that absorbs water, and the holes and electrons from excitons generated by the light of water molecules are generated. Promote dissociation,
I think that this is one of the causes of high sensitivity (Y.Fu
jimaki: IS & T ′s 7th International Congress on Adv
ance in Nonimpact Printing Technologies, Paper Sum
maries, 269 (1991)). When such a material is used as a carrier-generating substance, the sensitivity characteristics may change due to environmental changes, particularly humidity fluctuations, which causes practical problems and requires improvement.

On the other hand, in order to form the photosensitive layer, the desired titanyl phthalocyanine is usually added with a binder polymer in an organic solvent, and finely dispersed using various dispersing devices to obtain a dispersion liquid. Coating is performed on a conductive substrate. In general, a compound having a crystal polymorph has a different crystal stability depending on environmental conditions, and therefore a crystal state is often changed in a dispersion liquid under the influence of a solvent or a binder. In particular, titanyl phthalocyanine used in the present invention is used. Because of the very high photon efficiency of crystals, such slight changes in crystalline state have a significant effect on photoreceptor properties. Therefore, it is important to suppress such changes in the dispersion liquid, and it is further important to secure crystal stability in the photosensitive layer for a long period of time against environmental conditions and the like.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photosensitive member which has excellent sensitivity characteristics 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 provide an electrophotographic photosensitive member which has a small change in sensitivity characteristics with respect to humidity fluctuations.

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 and has little characteristic fluctuation.

[0015]

The above-mentioned object of the present invention is Cu-
In the electrophotographic photoreceptor using crystalline titanyl phthalocyanine, which has a maximum peak at 27.2 ± 0.2 degrees of Bragg angle 2θ in the X-ray diffraction spectrum for Kα ray, as a carrier generating substance, a hydroxyl group is substituted in the dispersion liquid or the photosensitive layer. This can be achieved by including the heterocyclic compound having a group in the range of 0.1 to 1000 parts by weight with respect to 100 parts by weight of titanyl phthalocyanine.

The chemical structure of titanyl phthalocyanine used in the present invention is represented by the following general formula [I].

[0017]

[Chemical 1]

The X-ray diffraction spectrum was measured under the following conditions, and the peak here is a sharp acute-angled protrusion 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. Various methods can be used for synthesizing the titanyl phthalocyanine used in the present invention, but typically, it can be synthesized according to the following reaction formula (1) or (2).

[0020]

[Chemical 2]

In the formula, R _{1 to} R ₄ represent a leaving group.

The titanyl phthalocyanine obtained as described above can be converted into the crystal form used in the present invention by the following treatment.

For example, titanyl phthalocyanine of any crystal form is dissolved in concentrated sulfuric acid, the sulfuric acid solution is poured into water, and the precipitated crystals are collected by filtration. By this operation, titanyl phthalocyanine is converted into an amorphous state.

Then, this amorphous titanyl phthalocyanine is treated with a specific organic solvent in the presence of water to obtain the crystal form used in the present invention. As a specific example of such a method, for example, JP-A-3-35
Examples described in No. 245 can be given.

The titanyl phthalocyanine used in the present invention has a maximum peak at 27.2 ± 0.2 degrees of Bragg angle 2θ, and also has a clear peak at the Bragg angles of 9.5 ± 0.2 degrees and 24.2 ± 0.2 degrees. .

The heterocyclic compound having a hydroxyl group as a substituent, which is used together with these titanyl phthalocyanines, is 5 to 6 containing an oxygen atom, a nitrogen atom and a sulfur atom.
A compound having a member ring, or a compound in which a plurality of them are condensed, or a cyclic compound formed by condensing them with a carbocycle and a substituent containing an OH group bonded directly or through an alkyl chain or an alkyloxy chain is there. Among these, compounds containing two or more substituents containing a hydroxyl group are more preferable.

Examples of the parent cyclic compound include pyridine ring, pyrimidine ring, piperidine ring, monophorine ring, furan ring, pyran ring, quinoline ring, coumarin ring, and saturated compounds of these compounds. You can Examples of compounds are shown below.

[0028]

[Chemical 3]

[0029]

[Chemical 4]

[0030]

[Chemical 5]

These compounds are titanyl phthalocyanines.
It is used in an amount of 0.1 to 1000 parts per 100 parts by weight, and 1 to 500 parts in a compound having two or more hydroxyl groups. If it is less than the above range, the effect is insufficient, and if it is more than the above range, the sensitivity characteristic of the photoreceptor is deteriorated. Derivatives of these heterocyclic compounds are more effective than those of the corresponding carbocycles, presumably because the heterocycles have a higher affinity for the titanyl phthalocyanine pigment particles than the carbocycles. This will be clarified in Examples described later.

In the electrophotographic photosensitive member of the present invention, other photoconductive substances may be used in combination with the above-mentioned phthalocyanine. Other photoconductive substances include titanyl phthalocyanine such as A, B, C, amorphous and AB mixed type which are different in crystal form from the titanyl phthalocyanine used in the present invention, other phthalocyanine compounds, naphthalocyanine compounds, and other porphyrins. Examples thereof include derivatives, azo compounds, polycyclic quinone compounds represented by dibromoanthanthrone, pyrylium compounds, eutectic complexes of pyrylium compounds, and squarylium compounds.

The electrophotographic photoreceptor of the present invention may be used in combination with a carrier transport material. Although various substances can be used as the carrier-transporting substance, typical examples thereof include compounds having a nitrogen-containing heterocyclic nucleus represented by oxazole, oxadiazole, thiazole, thiadiazole, imidazole and the like, and a condensed ring nucleus thereof, poly Arylalkane compounds, pyrazoline compounds, hydrazone compounds, triarylamine compounds, styryl compounds, polis (bis) styryl compounds, styryltriphenylamine compounds, β-phenylstyrylphenylamine compounds, butadiene compounds , Hexatriene compounds,
Examples thereof include carbazole compounds and condensed polycyclic compounds. 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.

[0034]

[Chemical 6]

[0035]

[Chemical 7]

[0036]

[Chemical 8]

[0037]

[Chemical 9]

[0038]

[Chemical 10]

[0039]

[Chemical 11]

Various forms of the photoconductor are known. The photoconductor of the present invention may take any of these forms, but it is preferable to use a laminated or dispersed function-separated photoconductor. In this case, the structure is usually as shown in FIGS. In the layer structure shown in FIG. 1A, a carrier generation layer 2 is formed on a conductive support 1, a carrier transport layer 3 is laminated on the carrier generation layer 2, and a photosensitive layer 4 is formed. () Is a photosensitive layer 4'in which the carrier generating layer 2 and the carrier transporting layer 3 are reversed. FIG. 3C shows an intermediate layer 5 provided between the photosensitive layer 4 and the conductive support 1 having the layer structure shown in FIG. The layer structure of FIG. 5 (5) is one in which a photosensitive layer 4 ″ containing a carrier generating substance 6 and a carrier transporting substance 7 is formed. Intermediate layer 5 between 1 and
Is provided. In the structure shown in FIG. 1, a protective layer may be further provided on the outermost layer.

The heterocyclic compound containing a hydroxyl group according to the present invention can be added to any of these layers.
It is preferable to add the carrier generation layer, the carrier transport layer, and the intermediate layer. The carrier generating layer is particularly effective.

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 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. The thickness of the carrier generation layer is 0.01 to 20 μm, more preferably 0.05 to 5 μm. The thickness of the carrier transport layer is 1 to 100 μm, more preferably 5 to 30 μm.

The above-mentioned 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, in the above-mentioned photosensitive layer, 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, "Sanol LS-2626",
Examples thereof include hindered amine compounds such as “Sanol LS-622LD” (manufactured by Sankyo Co.).

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. In addition, 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.

[0049]

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

Example 1 80 parts of methyl isobutyl ketone, 1 part by weight of polyvinyl butyral "BX-1" (manufactured by Sekisui Chemical Co.) and 1 part by weight of a titanyl phthalocyanine powder having an X-ray diffraction spectrum shown in FIG. ) 1 part by weight was added and dispersed by a sand mill to prepare a pigment coating solution. On the other hand, a thickness of "CM-8000" (manufactured by Toray Industries, Inc.) made of polyamide resin by coating on a polyester base on which aluminum is vapor-deposited.
An undercoat layer of 0.2 μm was provided. Then, the above-mentioned pigment coating liquid was applied to the wire bar to form a carrier generation layer having a thickness of 0.2 μm.
Next, 1 part by weight of carrier transporting material (CTM-1) and 1.5 parts by weight of polycarbonate "Iupilon Z-200" (manufactured by Mitsubishi Gas Chemical Co., Inc.) and a small amount of silicone oil "KF-54" (manufactured by Shin-Etsu Chemical Co., Ltd.) A solution dissolved in 8 parts by weight of 1,2-dichloroethane was blade-coated to form a carrier transport layer having a thickness of 23 μm. The photoreceptor thus obtained is referred to as Sample 1.

Examples 2 to 4 In Example 1, the exemplified compound 1 was replaced with the exemplified compounds 2, 3,
Photosensitive members were prepared in the same manner as in Example 1 except that the components 4, 5 and 6 were replaced. Samples 2 to 6 are used.

Comparative Example (1) A comparative photoconductor was obtained in the same manner as in Example 1 except that Exemplified Compound 1 was omitted. This is designated as Comparative Sample (1).

Comparative Example (2) A comparative photoconductor was obtained in the same manner as in Example 1 except that triethanolamine was used instead of Exemplified Compound 1. This is a comparative sample (2).

Comparative Example (3) A comparative photoconductor was obtained in the same manner as in Example 1 except that 1,3-cyclohexanediol was used instead of Exemplified Compound 1. This is a comparative sample (3).

Evaluation 1 The obtained sample was mounted on a modified "Konica 9028" (Konica Corporation, using a semiconductor laser light source) in an environment of 25 ° C. and 50% RH (relative humidity), and a grid voltage Vg- 750V
Then, the potential Vh of the unexposed portion and the potential Vl of the exposed portion at the time of light irradiation of 0.7 mw were measured. Then, the sample was repeatedly used for 10,000 prints, and Vh and Vl were also measured together. Next, after moving to an environment of 15 ° C and 20% RH and acclimatizing to the environment sufficiently, Vh and Vl were measured under the above-mentioned conditions, and Vh and Vl after repeated use of 10,000 prints were also combined. It was measured. The results are shown in Table 1.

[0056]

[Table 1]

The performance of the photoconductor of the present invention does not change significantly under various environments. Contrary to this, Comparative Example (1) to which the heterocyclic compound having a hydroxyl group of the present invention was not added showed a large decrease in sensitivity (Vl increase) at low humidity, and also, JP-A-64-44450.
Comparative sample (2) to which the existing wetting agent triethanolamine described in No. 1 is added is the potential (Vh) of the unexposed area.
The drop is significant. Moreover, the effect is small with cyclohexanediol.

[0058]

According to the structure of the present invention, a high-speed printer, a copying machine, which has little sensitivity and humidity fluctuation and has high durability,
A photoconductor for facsimile can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a photoconductor of the present invention.

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

[Explanation of symbols]

 1 Conductive Support 2 Carrier Generation Layer 3 Carrier Transport Layer 4 Photosensitive Layer 5 Intermediate Layer 6 Carrier Generation Material 7 Carrier Transport Material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihide Fujimaki, 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock company (72) Inventor Shinichi Suzuki, 1 Sakura-machi, Hino-shi, Tokyo Konica stock company In-house

Claims (3)

[Claims] 1. A titanyl phthalocyanine heterocyclic compound containing crystalline titanyl phthalocyanine having a maximum peak at 27.2 ± 0.2 degrees of Bragg angle 2θ in an X-ray diffraction spectrum for Cu-Kα rays and having a hydroxyl group as a substituent. An electrophotographic photosensitive member characterized by being contained in an amount of 0.1 to 1000 parts by weight with respect to 100 parts by weight. 2. The method according to claim 1, wherein the heterocyclic compound having two or more hydroxyl groups as a substituent is contained in an amount of 1 to 500 parts by weight based on 100 parts by weight of titanyl phthalocyanine. An electrophotographic photosensitive member. 3. The titanyl phthalocyanine according to claims 1 and 2 has a maximum peak at 27.2 ± 0.2 degrees,
In addition, an electrophotographic photoreceptor characterized by having clear peaks at 9.5 ± 0.2 degrees and 24.2 ± 0.2 degrees.