JP3008601B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member having an undercoat layer, and more particularly to an electrophotographic photosensitive member having an undercoat layer capable of improving the sensitivity over conventional materials.

[0002]

2. Description of the Related Art The basic constitution of an electrophotographic photoreceptor is one in which a photosensitive layer is formed on a conductive support. An undercoat layer is provided to prevent unnecessary charge injection, protect against electrical breakdown, or cover defects on a support. Conventionally, as an undercoat layer, for example, polyvinyl methyl ether, poly-N-vinyl imidazole, polyethylene oxide, ethyl cellulose,
Methylcellulose, ethylene-acrylic acid copolymer, polyamide, casein, gelatin, polyethylene, polyester, phenolic resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, polyvinylpyrrolidone, polyvinylpyridine, polyurethane, polyglutamic acid, polyacrylic acid, etc. It is known to use the above resin material. Among these resin materials, a soluble polyamide resin is particularly preferred (Japanese Patent Application Laid-Open No. 51-114132).
JP-A-52-25638 and JP-A-56-2112
No. 9, No. 58-95351). Among them, N-alkoxymethylated nylon described in JP-A-58-95351 is a material having a good balance of various properties and is preferably used.

[0003]

Conventionally, as the N-alkoxymethylated nylon in the undercoat layer, nylon 6 as a raw material has been mainly used. N-alkoxymethylated nylons have different physical properties depending on the type of raw material nylon to be alkoxymethylated, and when they are used for the undercoat layer, the characteristics of the photoreceptor slightly vary, and always satisfactory results can be obtained. Was not something that could be done. The present invention has been made in view of such circumstances, and an object thereof is to provide an electrophotographic photoreceptor having excellent characteristics using an N-alkoxymethylated nylon for an undercoat layer. .

[0004]

The present inventors have prepared various types of nylons which have been alkoxymethylated, and have studied the characteristics when using them as an undercoat layer. Nylon was found, and the present invention was completed. That is, the electrophotographic photoreceptor of the present invention has an undercoat layer between the conductive support and the photosensitive layer, and the undercoat layer contains a nylon resin obtained by N-alkoxymethylation of nylon 12. It is characterized by.

Hereinafter, the present invention will be described in detail. In the present invention, as the conductive support, aluminum,
Conductive treatments such as a metal drum or sheet such as copper or stainless steel, a plastic film or paper laminated with a metal foil such as aluminum, or a material obtained by vapor-depositing aluminum, gold, or the like can be used. The surface of the conductive support can be subjected to various treatments within a range that does not affect the image quality. For example, oxidation treatment or chemical treatment of the surface can be performed.

The undercoat layer on the conductive support is made of nylon 1
N-alkoxymethylated nylon resin 2, i.e., formed using N-alkoxymethylated nylon 12, specifically, methoxymethylated, ethoxymethylated, propoxymethylated and butoxymethylated nylon 12 Etc. are used.

Since the nylon resin used in the present invention is N-alkoxylated using nylon 12 as a raw material, the solubility of nylon 12 in a solvent is increased, the solution is hardly gelled, and the nylon resin is formed using the same. The undercoat layer increases the adherence to the photosensitive layer applied thereon, and makes the photosensitive layer more firmly adhered. Also, N
-Than when using alkoxymethylated nylon 6,
When the photosensitive layer is applied, the solvent of the photosensitive layer easily penetrates, and a concentration gradient occurs at the interface between the undercoat layer and the photosensitive layer, that is,
Instead of a clear layer structure, a mixed boundary area between them is created, which in turn gives good results in electrical characteristics, etc.
Quality improvement such as easy flow of electric charges is provided.

In order to form the undercoat layer, a coating solution obtained by dissolving the N-alkoxymethylated nylon 12 in alcohol may be applied. As the alcohol, for example, methanol, ethanol, butanol, n-propyl alcohol, i-propyl alcohol and the like are used. A plurality of alcohols may be used. The dissolution of the N-alkoxymethylated nylon 12 in the solvent is easily performed. That is, as in the case of N-alkoxymethylated nylon 6, there is no need to take a time-consuming method of first dissolving in methanol heated to 40 ° C. and then mixing other alcohols. It only needs to be added.

The undercoat layer may contain alumina-coated titanium oxide fine particles, as described in JP-A-2-181158. When alumina-coated titanium oxide is dispersed in the undercoat layer, the dielectric constant of titanium oxide is high, so that the dielectric constant of the layer can be increased and the film can be made thick. In addition, the effect of dispersibility can be improved by coating with alumina. Furthermore, the undercoat layer in which alumina-coated titanium oxide is dispersed has a high concealing effect of the base conductive support, and does not cause any problem such as slight scratches. Further, since the scattering effect on incident light is high, interference does not occur even when coherent light (for example, laser light) enters. This is an effect due to the high refractive index of titanium oxide, and it is possible to obtain a photoconductor free of interference fringes.

The alumina-coated titanium oxide fine particles used in the present invention can be produced, for example, as follows. For example, titanium oxide fine particles having a particle size of about 0.1 to 0.8 μm are dispersed in an aqueous solution of an aluminum salt such as aluminum chloride, and an alkali such as caustic soda is added therein to convert aluminum hydroxide to titanium oxide fine particles. Deposited on the surface of Next, the titanium oxide fine particles are ignited at about 500 ° C. to obtain alumina-coated titanium oxide fine particles. The amount of alumina to be coated is preferably set to about 1 to 10% by weight based on titanium oxide. The mixing ratio of the alumina-coated titanium oxide fine particles to the nylon resin is preferably set in the range of 4: 1 to 1: 4. When the ratio of the latter is large, the effect of increasing the thickness of the undercoat layer is small, and when the ratio of the former is large, the film formability and strength of the coating film of the undercoat layer become insufficient.

In order to obtain a coating solution containing alumina-coated titanium oxide fine particles, alumina-coated titanium oxide fine particles are added to an alcohol solution of a polyamide resin, and a ball mill, a roll mill, a sand mill, a paint shaker, an attritor, an ultrasonic wave or the like is used. What is necessary is just to process by means.
For example, in the case of a sand mill, about 30 minutes is sufficient for the dispersion treatment. A photosensitive layer is formed on the undercoat layer. The photosensitive layer may have a single-layer structure, but preferably has a laminated structure in which the function is separated into a charge generation layer and a charge transport layer.

When the photosensitive layer has a single-layer structure, a known material in which a photosensitive material is dispersed in a binder resin can be used. Examples include a dye-sensitized ZnO photosensitive layer, a CdS photosensitive layer, and a photosensitive layer in which a charge generating substance is dispersed in a charge transporting substance.

When the photosensitive layer has a laminated structure, a charge generation layer is first formed. It is formed by dispersing a charge generating substance in a binder resin as required. Examples of the charge generating material include selenium and selenium alloys; CdS, CdSe, and CdS.
Inorganic photoconductors such as Se, ZnO and ZnS; metal phthalocyanine and metal-free phthalocyanine pigments: squarium compounds, azurenium compounds, perylene pigments; indigo pigments; quinacridone pigments; polycyclic quinone pigments; A charge transfer complex comprising N-vinylcarbazole and trinitrofluorenone;
An eutectic complex comprising a pyrylium salt dye and a polycarbonate resin is exemplified. Well-known binder resins,
For example, polycarbonate, polystyrene, polyester, polyvinyl butyral, methacrylate polymer or copolymer, vinyl acetate polymer or copolymer, cellulose ester or ether, polybutadiene, polyurethane, epoxy resin and the like are used. The thickness of the charge generation layer is generally 0.1 to 5 μm, preferably 0.2 to 2.0 μm.
μm is appropriate.

A charge transport layer is formed on the charge generation layer. The charge transporting layer is formed by dispersing a charge transporting material in a binder resin as needed, and as the charge transporting material, a material which is transparent to visible light and has a charge transporting ability. It is not particularly limited. Specific examples include imidazole, pyrazoline, thiazole, oxadiazole, oxazole, hydrazone, ketazine, azine, carbazole, polyvinylcarbazole and the like and derivatives thereof, triphenylamine derivatives, stilbene derivatives, benzidine derivatives and the like. As the binder resin, any resin may be used as long as it has a film-forming property.For example, polycarbonate, polyarylate, polyester, polystyrene, styrene-acrylonitrile copolymer, polysulfone, polymethacrylate, styrene -Methacrylic acid ester copolymers. The charge transport layer is applied by dissolving these materials in a solvent. The thickness of the charge transport layer is 5 μm or more.
About 30 μm is appropriate. In the present invention, the order of lamination of the charge generation layer and the charge transport layer may be reversed.

[0015]

EXAMPLES Example 1 6 parts of N-methoxymethylated nylon 12 resin (trade name: Toresin G550, manufactured by Teikoku Chemical Industry Co., Ltd.) (parts by weight,
The same applies hereinafter) in 60 parts of methanol and 34 parts of n-butanol to obtain a solution for forming an undercoat layer. A mirror-cut aluminum pipe of 84 mmφ × 310 mm was prepared as a substrate, and the solution was applied by a ring coating machine. After drying at 120 ° C. for 10 minutes, an undercoat layer having a thickness of 1.0 μm was formed. On the other hand, 1 part of a polyvinyl butyral resin (trade name: BM1, manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 19 parts of cyclohexanone. To this solution is added dibromant anthrone pigment (CI Pigment Red 168).
8 parts and 0.02 parts of trifluoroacetic acid were mixed. Next, dispersion treatment was performed by a sand mill using 1 mmφ glass beads as a dispersion medium. Cyclohexanone was further added to the resulting dispersion to prepare a coating solution having a solid content of about 10%. This coating solution was applied on the undercoat layer formed above using a ring coating machine, and heated and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.8 μm. '-Diphenyl-N, N'-bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-
4 parts of diamine as charge transport material, polycarbonate Z
The resin was dissolved in 40 parts of monochlorobenzene together with 6 parts of the resin. The obtained solution was applied by a dip coating method,
After drying at 1 ° C. for 1 hour, a charge transport layer having a thickness of 20 μm was formed.

Comparative Example 1 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that a quaternary copolymer nylon resin (trade name: CM8000, manufactured by Toray Industries, Inc.) was used as a material for forming the undercoat layer. did.

Comparative Example 2 A photoreceptor was prepared by using N-methoxymethylated nylon 6 resin (trade name: Toresin F30, manufactured by Teikoku Chemical Industry Co., Ltd.) as a material for forming an undercoat layer. However, when dissolving the resin, a method was first employed in which the resin was dissolved in methanol heated to 40 ° C., and then butanol was added.

For these electrophotographic photoreceptors, -820 V
(A) with a scorotron charger having a grid maintained at a constant voltage of 9.0 ergs / cm ² after 1 ^second.
Discharge was performed by irradiating white light (B).
Irradiate green light of ergs / cm ^{2 to} remove electricity (C)
, The potential of each part was measured.
It can be said that the higher the potential of (A), the higher the potential of the photoreceptor, and the less the unnecessary charge is injected.
The lower the potential of (B), the higher the sensitivity, and the lower the potential of (C), the less the residual charge, the less the image memory and the less the fogging. 22 ° C of each electrophotographic photoreceptor, 5
Table 1 shows the measurement results at 5% RH.

[0019]

[Table 1] Next, Table 2 shows the measurement results at 15 ° C. and 15% RH.

[0020]

[Table 2] From the above results, the photoreceptor of Example 1 had higher sensitivity than that of the comparative example, and the decrease in sensitivity was small even under a low-temperature and low-humidity environment.

Example 2 Alumina-coated titanium oxide powder (trade name: SR-1T, manufactured by Sakai Chemical Industry Co., Ltd.) was mixed with the undercoat layer forming solution prepared in Example 1 twice as much as the resin. Then, the mixture was dispersed with 2 mmφ glass beads using a paint shaker for 30 minutes. A 60 mmφ × 260 mm mirror-polished aluminum pipe was prepared as a substrate, and the above dispersion was applied by a ring coater. Next, drying was performed at 120 ° C. for 10 minutes to form an undercoat layer having a thickness of 3.0 μm.
Next, a polyvinyl butyral resin (trade name: Esrec B)
M-1 manufactured by Sekisui Chemical Co., Ltd.) was previously dissolved in 100 parts of cyclohexanone, mixed with 3 parts of X-type metal-free phthalocyanine, dispersed in a sand mill for 5 hours, diluted with cyclohexanone, and solidified. A coating solution for forming a charge generation layer having a concentration of 3.5% by weight was prepared. Using this coating solution, a ring coating machine was used to coat the undercoat layer with 100 °
C, and dried for 10 minutes to form a charge generation layer having a thickness of 0.25 μm. A charge transport layer was formed thereon in the same manner as in Example 1. The photoreceptor thus manufactured was changed to -60
The evaluation was performed by a printer having an electrophotographic process such as 0 V charging, image exposure with a semiconductor laser, reversal development with a negatively charged developer, and transfer to paper. It was -100V when the electric potential of the light irradiation part was measured. There were no problems when printing out print images in various patterns.

[0022]

Since the electrophotographic photoreceptor of the present invention uses N-alkoxymethylated nylon in the undercoat layer, it has excellent adhesion between the conductive support and the photosensitive layer, and has excellent sensitivity. Has electrophotographic properties. Further, since N-alkoxymethylated nylon has high solubility in a solvent, the number of steps for dissolution at the time of forming the undercoat layer can be reduced. In the present invention, when alumina-coated titanium oxide is dispersed in the undercoat layer, the thickness of the undercoat layer can be made larger (for example, 3.0 μm), so that the characteristics can be improved and interference fringes can be prevented. effective.

Continuation of front page (72) Inventor Nobuyuki Ichizawa 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. Takematsu Office (56) References JP-A-2-181158 (JP, A) JP-A-56-21129 (JP) JP-A-58-95351 (JP, A) JP-A-52-25638 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/14

Claims (2)

(57) [Claims] 1. An electrophotographic photoreceptor having an undercoat layer between a conductive support and a photosensitive layer, wherein the undercoat layer contains a nylon resin obtained by N-alkoxymethylation of nylon 12. Electrophotographic photoreceptor. 2. The electrophotographic photoreceptor according to claim 1, wherein alumina-coated fine particles of titanium oxide are dispersed in the undercoat layer.