JP2001051434A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of a photoreceptor due to light in an electrophotographic device and to enhance durability in repetitive use and resistance to an environmental change by incorporating a specified triphenylamine compound as an electric charge transferring material and a specified hindered amine compound as an additive into the electric charge transferring layer of the photoreceptor. SOLUTION: An electric charge generating layer and an electric charge transferring layer are disposed on an electrically conductive substrate to obtain the objective electrophotographic photoreceptor. The electric charge transferring layer contains a triphenylamine compound of formula I as an electric charge transferring material and a hindered amine compound of formula II as an additive. In the formula I, Z1 is H or 1-2C alkyl and Z2 and Z3 are each H, 1-2C alkyl or halogen. In the formula II, R is H, alkyl, alkenyl, aryl, acyl or aralkyl.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreceptor for organic electrophotography (hereinafter, also simply referred to as a "photoreceptor"), and more particularly, to an electrophotographic photoreceptor for improving a constituent material of a charge transport layer.

[0002]

2. Description of the Related Art In an electrophotographic system based on the invention of Carlson, the surface of an electrophotographic photosensitive member is charged, an electrostatic latent image is formed by exposure, and the latent image is developed with toner (visible image). The visible image is transferred to paper. The photoreceptor then removes any residual toner attached,
After static elimination, it is repeatedly used from the exposure step. The characteristics required for such a photoreceptor include not only good charge characteristics, charge retention characteristics in a dark place, and charge dissipating property (sensitivity) during light irradiation, but also when used repeatedly for a long time. It is required to be durable and resistant to environmental changes during use. Conventionally, as a material used for such a photoreceptor, an inorganic photoconductive material such as selenium, a selenium alloy, zinc oxide, and cadmium sulfide has been often used.

Recently, an organic photoconductive material has been used, taking advantage of advantages such as generally low toxicity, transparency, film formability, light weight, and productivity as compared with inorganic photoconductors. The development of photoconductors has been actively pursued. Among them, the function separation type laminated organic photoreceptor in which the charge generation layer and the charge transport layer are separated, the sensitivity can be greatly improved by forming and combining each layer with a material optimal for each function,
Further, it has many advantages such as setting a spectral sensitivity according to a desired exposure wavelength, and is widely used in electrophotographic devices such as copiers, printers, and faxes.

[0004] Further, with respect to the photoreceptor, as conventional problems, repelling, bumping, unevenness, etc. are generated due to a very small defect, dirt attached matter, scratch, etc. on the conductive support.
There are drawbacks such as white spots appearing on the image due to uneven charge injection from the support. Therefore, in order to improve these disadvantages, a layer such as alumite, which is generally called an undercoat layer, is often provided.

[0005] Many of the functionally separated laminated organic photoreceptors that are currently in practical use have an undercoat layer, a charge generation layer, and a charge transport layer laminated on a conductive support in this order. The charge generation layer is mainly composed of a charge generation material that generates charge by irradiation with exposure light, and a resin that adheres the charge generation material to upper and lower layers. In addition, the charge transport layer is required to have an insulating property in a dark place and a conductivity in a bright place, and the optical semiconductor characteristics are determined by the chemical structure of the charge transport substance.

[0006]

In an electrophotographic apparatus called a high-speed printer or a high-speed copier, which has recently been frequently used, a highly-sensitive high-sensitivity photoconductor is used. Requires a highly sensitive charge transport material. However, the higher the sensitivity of the charge transport material, the more easily it reacts to even a small amount of light, making the potential unstable.Moreover, the deterioration due to light tends to be large. May occur.

On the other hand, it is important to extend the life of the photosensitive member from the viewpoint of energy saving. Among them, it is necessary to improve durability in repeated use and resistance to environmental changes. Preventing the deterioration of the photoreceptor due to ozone, oxidizing gas, light, or heat generated in the photoconductor is an important issue in the development of the photoreceptor. Various additives have been proposed to prevent the above-described photodegradation, but none of them has yet been obtained with a sufficient effect.

Accordingly, an object of the present invention is to improve the photodeterioration inhibitor to be added to the photosensitive layer by focusing on the photodeterioration inhibitor among the additives for preventing the photoreceptor from deteriorating. An object of the present invention is to provide a photoconductor for electrophotography in which the photoconductor is prevented from deteriorating due to light in the apparatus, and has improved durability when repeatedly used and resistance to environmental changes.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, a triphenylamine compound represented by the following general formula (I) was added to the charge transport layer: The inventors have found that by adding a hindered amine compound represented by the following general formula (II) in combination, a photoconductor having high sensitivity, high repetition durability and high environmental durability can be produced, and the present invention has been completed. Was.

That is, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a charge generation layer and a charge transport layer provided on a conductive support. General formula (I), (In the formula, Z ¹ represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and Z ² and Z ³ represent a hydrogen atom and 1 to 2 carbon atoms.
Represents an alkyl group or a halogen atom. ) And an additive represented by the following general formula (II): (Wherein, R represents a hydrogen atom, or an alkyl group, an alkenyl group, an aryl group, an acyl group, or an aralkyl group).

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual cross-sectional view of a function-separated laminated electrophotographic photosensitive member according to an example of the present invention. An undercoat layer 2 is provided on a conductive support 1, and a charge generation layer 3 is further provided thereon. And a photosensitive layer 5 composed of a charge transport layer 4.

The conductive support 1 serves not only as an electrode of the photoreceptor but also as a support for other layers, and may be any of a cylinder, a plate, and a film. In addition to a metal such as iron, a support such as a plastic that has been made conductive by depositing a metal on the surface or forming a coating film in which a conductive powder is dispersed can be used.

An undercoat layer 2 may be formed on the surface of the conductive support 1 if necessary. This undercoat layer 2 can be formed of polyvinyl alcohol resin, polyamide resin, polyurethane resin, melamine resin, epoxy resin or phenol resin, aluminum oxide, or the like.

The charge generation layer 3 is formed by forming a charge generation substance by vacuum evaporation or dispersing the charge generation substance in an organic solvent together with a binder resin.
It is formed by coating. As a charge generation material,
Amorphous selenium, crystalline selenium, selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds and alloys, inorganic photoconductors such as zinc oxide and titanium oxide, azo dyes such as chlorodiane blue, anthantrone Quinone pigments such as pyrenequinone, quincyanine pigments, perylene pigments, perinone pigments, indigo pigments, bisbenzimidazole pigments, metal-free phthalocyanines, titanyl phthalocyanines, tin phthalocyanines, gallium phthalocyanines, copper phthalocyanines, phthalocyanine pigments such as vanadyl phthalocyanines, azulhenium salts, Various organic pigments and dyes such as squarium pigments, quinacridone pigments, azo pigments, anthroquinone pigments, pyrene pigments, pyrylium salts, and thiapyrylium salts can be used. Also,
These organic pigments generally have several types of crystals,
In particular, phthalocyanine pigments are known in various crystal forms, including α, β, etc., but in the present invention, any pigment can be used as long as it is a pigment that can achieve the desired sensitivity. Is also good.

As the binder resin in the charge generation layer 3,
Melamine resin, epoxy resin, silicone resin, polyurethane resin, acrylic resin, polycarbonate resin, polyarylate resin, phenoxy resin, polyester resin,
Polyvinyl butyral resin, methacrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin and copolymer resin containing two or more of these repeating units, for example, vinyl chloride-vinyl acetate copolymer resin, acrylonitrile-styrene copolymer Insulating resins such as polymer resins can be used, but all commonly used resins can be used alone or in combination of two or more.

In the present invention, the charge transport material of the charge transport layer 4 is represented by the following general formula (I): The compound represented by is contained. The compound belongs to the triphenyl amine, the substituents Z ¹ in formula (I) is a hydrogen atom or a number 1-2 alkyl group having a carbon
Z ² and Z ^{3 each} represent a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, or a halogen atom. Specific examples of such compounds are shown below, but are not limited thereto.

[0017]

[0018]

The charge transporting layer 4 includes, in addition to the charge transporting material of the present invention, a hydrazone compound, a pyrazoline compound, a triphenylamine compound, a triphenylmethane compound, a stilbene compound, an oxadiazole compound. Compounds, enamine-based compounds, triazine-based compounds, quinazoline-based compounds, benzofuran-based compounds, carbazole-based compounds, quinone-based compounds, fluorenone-based compounds, xanthone-based compounds, etc. can be used alone or in combination of two or more. It is.

The binder resin used for the charge transport layer 4 includes
Insulating resin such as acrylic resin, polyarylate, polyester resin, polycarbonate resin, polystyrene resin, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, etc. Or organic photoconductive polymers such as polyvinyl carbazole, polyvinyl anthracene, and polyvinyl pyrene.

The charge transport layer 4 can be formed by applying and drying a solution obtained by dissolving the above-described charge transport material and binder resin in an appropriate solvent. Examples of the solvent used for forming the charge transport layer 4 include aromatic hydrocarbons such as toluene and xylene, halogenated aliphatic hydrocarbons such as methylene chloride, monochlorobenzene and chloroform, and ketones such as acetone and 2-butanone. And cyclic or linear ethers such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether, or a mixed solvent thereof.

In the present invention, the charge transport layer 4 contains the following general formula (II) as a photo-deterioration inhibitor: The compound represented by is contained. The above compounds belong to hindered amines, wherein the substituent R in the formula is a hydrogen atom,
Or an alkyl group, an alkenyl group, an aryl group, an acyl group, or an aralkyl group. The compound is preferably contained in the charge transport layer in a range of 0.001 to 10% by weight, more preferably 0.02 to 3% by weight. Specific examples of such compounds are shown below, but are not limited thereto.

[0023]

The photosensitive layer 5 contains an antioxidant other than the compound according to the present invention for the purpose of preventing deterioration of the photosensitive member due to ozone or oxidizing gas generated in the electrophotographic apparatus, or light or heat. Additives such as a light deterioration inhibitor and a heat stabilizer can also be added. The coating can be performed by using a coating method such as a dip coating method, a spray coating method, a ring coating method, a bead coating method, a blade coating method, and a roller coating method.

[0025]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. Example 1 On a 30 mm x 30 mm x 1 mm aluminum conductive support, 1.5 parts by weight of a polyamide resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) as an undercoat layer were mixed with 40 parts by weight of methanol and methylene chloride. A solution prepared by dissolving in a mixed solution of 60 parts by weight was applied,
After drying for minutes, an undercoat layer having a thickness of 0.2 μm was provided.

Next, 10 parts by weight of an X-type metal-free phthalocyanine as a charge generating substance, and 10 parts by weight of a polyvinyl acetal resin (trade name: Esrec KS-1, manufactured by Sekisui Chemical Co., Ltd.) as a binder resin. , Cyclohexanone 1
00 parts by weight was subjected to a dispersion treatment for 4 hours by a sand grinder using 0.25 mm zirconia balls as a spherical fine pulverizing medium. This dispersion is added with tetrahydrofuran 60
The mixture was diluted by adding 0 parts by weight, dip-coated on the undercoat layer, and dried at 100 ° C. for 30 minutes to provide a 0.3 μm-thick charge generation layer.

Further, as a charge transporting substance, 5 parts by weight of the compound represented by the specific example (I-1) and the following structural formula (1): And 5 parts by weight of a compound represented by the following formula: polycarbonate (trade name: G-400, molecular weight 4000) as a binder resin
0, manufactured by Idemitsu Kosan Co., Ltd.), 10 parts by weight of dibutylhydroxytoluene, and 0.005 parts by weight of the compound of the specific example (II-1) were dissolved in 70 parts by weight of tetrahydrofuran. After dip coating on the charge generation layer, 100
Drying was performed at 60 ° C. for 60 minutes to provide a charge transport layer having a thickness of 16 μm. As described above, a laminated photoreceptor having three layers was produced.

Example 2 In Example 1, the specific example (II-
Example 1 was repeated except that 0.05 part by weight of the compound of 1) was added.
A photoconductor sample was prepared in the same manner as described above.

Example 3 In Example 1, the specific example (II-
A photoconductor sample was prepared in the same manner as in Example 1, except that 0.5 part by weight of the compound of 1) was added.

COMPARATIVE EXAMPLE 1 In Example 1, the above-mentioned specific example (II-
A photoconductor sample was prepared in the same manner as in Example 1 except that the compound of 1) was not added.

Comparative Example 2 A photoreceptor sample was prepared in the same manner as in Example 1 except that only 10 parts by weight of the compound represented by the structural formula (1) was used as the charge transporting material of the charge transporting layer. did.

Comparative Example 3 A photoreceptor sample was prepared in the same manner as in Example 2 except that only 10 parts by weight of the compound represented by the structural formula (1) was used as the charge transporting material in the charge transporting layer. did.

Comparative Example 4 A photoreceptor sample was prepared in the same manner as in Example 3 except that only 10 parts by weight of the compound represented by the structural formula (1) was used as the charge transporting material of the charge transporting layer. did.

Comparative Example 5 In Example 1, only 10 parts by weight of the compound represented by the structural formula (1) was used as the charge transporting material of the charge transporting layer.
A photoconductor sample was prepared in the same manner as in Example 1, except that the compound of the specific example (II-1) was not added.

Example 4 On a 30 mm × 30 mm × 1 mm aluminum conductive support, 1.5 parts by weight of a polyamide resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) as an undercoat layer were 40 parts by weight of methanol. Then, a solution dissolved in a mixed solution of methylene chloride and 60 parts by weight was dip-coated and dried at 100 ° C. for 15 minutes to form an undercoat layer having a thickness of 0.2 μm.

Next, the following structural formula (2) as a charge generating substance: And a polyvinyl butyral resin as a binder resin (trade name: Eslek KS-5)
Z, manufactured by Sekisui Chemical Co., Ltd.) and 10 parts by weight of cyclohexanone as a finely pulverized medium having a particle size of 0.2
The dispersion treatment was performed for 2 hours with a sand grinder using 5 mm zirconia balls. The dispersion was diluted by adding 700 parts by weight of methyl isobutyl ketone, dip-coated on the undercoat layer, and dried at 100 ° C. for 15 minutes to form a film having a thickness of 0.3.
A μm charge generation layer was provided.

Further, 15 parts by weight of the compound of the specific example (I-2) as a charge transporting substance and the specific example (I-
5) parts by weight of the compound of 6) and polycarbonate as a binder resin (trade name: PCZ-300, molecular weight 30,000,
10 parts by weight of Mitsubishi Gas Chemical Co., Ltd., 0.1 part by weight of dibutylhydroxytoluene, and 0.001 part by weight of the compound of the specific example (II-3) were dissolved in 65 parts by weight of tetrahydrofuran. After dip coating on the generating layer, 100
Drying was performed at 60 ° C. for 60 minutes to provide a 17 μm-thick charge transport layer. As described above, a laminated photoreceptor having three layers was produced.

Example 5 In Example 4, the specific example (II-
Example 4 except that 0.01 part by weight of the compound of 3) was added.
A photoconductor sample was prepared in the same manner as described above.

Example 6 In Example 4, the above-mentioned specific example (II-
A photoconductor sample was prepared in the same manner as in Example 4, except that 0.1 part by weight of the compound of 3) was added.

COMPARATIVE EXAMPLE 6 In the same manner as in Example 4, the specific example (II-
A photoconductor sample was prepared in the same manner as in Example 4, except that the compound of 3) was not added.

The photoreceptors produced in Examples 1 to 3 and Comparative Examples 1 to 5 were evaluated by measuring the electrical characteristics of the photoreceptor before and after irradiating with a 1000-lux fluorescent light for 10 minutes. The measurement was performed using an electrostatic charging tester EPA810
Using 0 (manufactured by Kawaguchi Electric Works), the initial charge potential was measured by a constant current method adjusted to allow a current of 20 μA to flow through the tungsten wire. Next, 78 of the light quantity of 1 μW
Exposure was performed with 0 nm monochromatic light, and the exposure amount (sensitivity) required for the surface potential to attenuate to half of the initial surface potential was determined.

This measurement was performed before, immediately after, 30 minutes, 1 hour, 3 hours, and 24 hours after light irradiation, and the results were compared. These results are summarized in Table 1 below for the photoreceptors of Examples 1 to 3 and Comparative Examples 1 to 5 in terms of the relationship between the amount of the photodegradation inhibitor and the electrical properties of the photodegradation inhibitor. Show.

[0043]

[Table 1]

The photosensitive members produced in Examples 4 to 6 and Comparative Example 6 were evaluated by measuring the electrical characteristics of the photosensitive members before and after irradiating with a 1,000-lux fluorescent lamp for 10 minutes. The measurement was performed using an electrostatic charging tester EPA8100
(Kawaguchi Electric Works) was used to measure the initial charge potential by a constant current method adjusted to allow a current of 20 μA to flow through the tungsten wire. Next, exposure was performed with white light having an illuminance of 5 lx · s, and an exposure amount (sensitivity) required for decreasing the surface potential to half of the initial surface potential was obtained.

This measurement was performed before, immediately after, 30 minutes, 1 hour, 3 hours, and 24 hours after light irradiation, and the results were compared. Table 2 below summarizes the results of the photoreceptors of Examples 4 to 6 and Comparative Example 6 with respect to the type of photodeterioration inhibitor and the relationship between the amount of the inhibitor and the electrical characteristics.

[0046]

[Table 2]

As is clear from Tables 1 and 2, the photoreceptor of the present invention prepared by using a triphenylamine compound as a charge transport material in the charge transport layer and further adding a hindered amine compound to the charge transport layer. It was found that a remarkable effect was obtained on the recovery of the charged potential after irradiation.

[0048]

According to the present invention, in an electrophotographic photoreceptor having a charge generation layer and a charge transport layer on a conductive support, the charge transport layer contains a charge transport material represented by the above general formula (I). By containing the triphenylamine compound represented by the formula (I) and the hindered amine compound represented by the formula (II) as an additive, the photoreceptor is prevented from being deteriorated by light in an electrophotographic apparatus, and is used repeatedly. Can be improved in durability and resistance to environmental changes.

[Brief description of the drawings]

FIG. 1 is a conceptual cross-sectional view of an example of a function-separated laminated electrophotographic photosensitive member of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive support 2 undercoat layer 3 charge generation layer 4 charge transport layer 5 photosensitive layer

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a charge-transporting layer and a charge-generating layer provided on a conductive support, wherein the charge-transporting layer contains a charge-transporting substance represented by the following general formula (I): (In the formula, Z ¹ represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and Z ² and Z ³ represent a hydrogen atom and 1 to 2 carbon atoms.
Represents an alkyl group or a halogen atom. ) And an additive represented by the following general formula (II): (Wherein, R represents a hydrogen atom or an alkyl, alkenyl, aryl, acyl, or aralkyl group) and a hindered amine compound represented by the formula: