JPH0348256A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain copies which have high image quality and are free from image blurs even at and under a high temp. and high humidity by specifying the surface resistance of an intermediate layer and using a resin soluble in alcohol as an essential component. CONSTITUTION:The intermediate layer of the electrophotographic sensitive body constituted by successively laminating at least a charge generating layer, charge transfer layer, intermediate layer, and protective layer on a conductive base has >=10<15>OMEGA surface resistance. In addition, there is a close relation between the surface resistance and the dissipation of electric charges at the electrophotographic sensitive body having the layer constitution essentially consisting of the resin soluble in alcohol. The charges are liable to dissipate an the image blur arises when the copy is formed if the surface resistance of the intermediate layer is below 10<15>OMEGA. The electrophotographic sensitive body which exhibits the high sensitivity and high durability and forms the good images free from the image blur even at and under the high temp. and high humidity is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a photoreceptor for electrophotography, and in particular, a photoreceptor for electrophotography that can provide high-quality copies without image blurring even under high temperature and high humidity conditions. This relates to photoreceptors.

[Conventional technology]

Photoreceptors using organic photoconductive materials are being actively researched and developed because of their light weight, ease of film coating5 manufacturing costs, and the wide variety of organic compounds available. For example, in the early days, photoreceptors containing polyvinyl Rubazole and 2.4.7-}-linitro-9-fluorenone described in Japanese Patent Publication No. 50-10496,
A photoreceptor in which polyvinyl Rubazole is sensitized with a biryllium salt dye, as described in Japanese Patent No. 8-25658, or a photoreceptor having a eutectic complex as its main component has been proposed. However, these photoreceptors do not have sufficient sensitivity and durability. Therefore, a functionally separated photoreceptor in which a charge generation layer and a charge transport layer are separated was proposed, and the photoreceptor described in Japanese Patent Publication No. 55-42380 is a combination of chlordiane blue and a hydrazone compound, and a bisazo compound is used as the charge generation material. Described in JP-A-53-133445, JP-A-54-
21728, JP-A-54-22834, and as a charge transport material, JP-A-58-198043.
No. 58-199352, etc. are known. However, none of these functionally separated photoreceptors are satisfactory in terms of mechanical and electrostatic durability. Regarding mechanical durability, it has been proposed to provide a protective layer on the surface of the photosensitive layer. For example, there is a technique (Japanese Unexamined Patent Publication No. 3338/1983) that increases the thickness of the protective layer to improve its strength and prevents fogging on copies due to residual potential by incorporating a resistivity reducing agent into the film. A protective layer with high mechanical strength is provided with a thickness of 0.5 to 2 ps to improve the durability of the photoreceptor (Japanese Patent Laid-Open No. 61
-51155), or one in which the abrasion resistance of the photoreceptor is improved by containing a fluororesin in the protective layer and reducing the surface slip resistance (Japanese Patent Application Laid-Open No. 62-272).
No. 281), but generally it is JP-A-57
As disclosed in No. 30846 and JP-A No. 58-60748, an intermediate layer is provided on the photosensitive layer from the viewpoint of charge retention or solvent resistance to protect the photosensitive layer when coating the protective layer. A structure is adopted in which layers are provided. However, most conventional intermediate layers are intended for adhesion to the photosensitive layer and protection of the photosensitive layer. For this reason, image evaluation is rarely satisfactory, and image defects such as image blurring occur under high humidity conditions. [Problems to be Solved by the Invention] The present invention solves the above-mentioned conventional drawbacks in a photoreceptor having an intermediate layer and a protective layer on a photosensitive layer, and provides copies with high image quality and no blurring even under high temperature and high humidity conditions. An object of the present invention is to provide an electrophotographic photoreceptor that can be used for electrophotography.

[Means to solve the problem]

According to the present invention, in an electrophotographic photoreceptor in which at least a charge generation layer, a charge transport layer, an intermediate layer and a protective layer are sequentially laminated on a conductive support, the intermediate layer has a surface resistance of 1015Ω.
The above provides an electrophotographic photoreceptor characterized by containing an alcohol-soluble resin as a main component.

The first feature of the electrophotographic photoreceptor of the present invention is that in a photoreceptor in which at least a charge generation layer, a charge transport layer, an intermediate layer, and a protective layer are sequentially laminated on a conductive support, the surface resistance of the intermediate layer is reduced. io'' Ω or more.The present inventor believes that in an electrophotographic photoreceptor having such a layer structure, the charge is retained on the intermediate layer during charging, but
In this case, there is a close relationship between the surface resistance of the intermediate layer and the dissipation of charge, and if the surface resistance of the intermediate layer is less than 1015 Ω, the charge will dissipate easily, resulting in image blurring when copying. In the worst case, no image may be obtained, and we found that this phenomenon also occurs in high temperature and high humidity environments. Therefore, the inventors found that by setting the surface resistance of the intermediate layer to 101 sΩ or more, an electrophotographic photoreceptor free from the above-mentioned drawbacks could be obtained, and the present invention was completed.

The surface resistance referred to in the present invention is measured by the following method. First, 30 pm of polycarbonate resin (Panlite K-1300: manufactured by Teijin Kasei) was applied as an insulating resin on an Al plate.
Coating and then heating at 130℃. Dry for 20 minutes to form an insulating film. On top of this, the resin for the intermediate layer is dissolved in an alcoholic solvent and applied by dip coating. Dry for 30 minutes at 130"C.
．． 3. form an intermediate layer. Next, a comb-shaped gold electrode was vapor-deposited on the intermediate layer as an electrode for resistance measurement to create a sample for surface resistance measurement. <The distance between the square electrodes is 300-
It is. The surface resistance was measured by applying a voltage between the electrodes of the sample prepared as above, and measuring the ■-■ characteristics at 23℃ and 30%RH.
This was obtained under the following environment. The second feature of the electrophotographic photoreceptor of the present invention is that an alcohol-soluble resin is used as the main component of the intermediate layer. Generally, in the case of such a layer configuration, the charge transport layer is affected by the components of the intermediate layer formed thereon, which may cause defects on the image, but the intermediate layer according to the present invention is alcohol-soluble. Since resin is used, such problems can be avoided. The reason for this is not clear at this point, but it is thought to be due to the following reasons. That is, the alcohol solvent used when applying an alcohol-soluble resin as an intermediate layer generally has almost no adverse effects such as dissolving the charge transport layer or precipitating the charge transport substance. This is thought to be due to the large difference in solubility parameters between the alcohol solvent and the charge transport layer. Therefore, it is considered that forming the intermediate layer on the charge transport layer will not cause any problems in terms of the image.

Alcohol-soluble resins include polyvinyl formal, polyvinyl acetoacetal, polyvinyl butyral, polyamide, acetyl cellulose, methyl cellulose, phenol resin, melamine resin, urea resin, amino resin,
Examples include alkyd resins, but it is preferable to use phenolic resins in terms of effectiveness. The thickness of the intermediate layer is usually 10. It is preferably 1 pa or less. The protective layer according to the present invention preferably has a low resistance, and such a low resistance protective layer is prepared by dissolving a binder resin in an appropriate solvent and then adding a conductive substance such as a metal oxide into the binder resin. It can be obtained by dispersing, coating this dispersion on the charge transport layer and drying it, and various additives may be added to the protective layer for the purpose of improving dispersibility, adhesion, and smoothness. Good too. The thickness of the protective layer is 1 to 101 Js, preferably 2 to 101 Js.
It's 7pm. If the thickness is less than 11, the mechanical strength of the protective layer will be weak, and the abrasion resistance will be low, making the protective layer ineffective for long-term use.If the thickness is more than 11, charges will accumulate in the protective layer. Residual potential increases during repeated use. There are no particular restrictions on the structure of the protective layer, and the specific resistance is 1015-
to"Ω'ell. Preferably, a non-dispersed system may be used as long as I011Ω"c is about 1. In this case, a photoreceptor with even higher sensitivity can be expected. The charge generation layer in the present invention is formed from a charge generation substance or a resin binder together with the charge generation substance.

Examples of the charge generating substance that can be used in the present invention include an azo pigment having a carbazole core, an azo pigment having a styrylstilbene core, an azo pigment having a triphenylamine skeleton, an azo pigment having a dibenzylthiophene core, Azo pigments with oxadiazole cores, azo pigments with fluorenone cores, azo pigments with bisstilbene cores, azo pigments with distyryloxazole cores, azo pigments with distyryl rubazole cores, diphenylamine cores azo pigments having carbazole bone cores, trisazo pigments having carbazole bone cores, metal phthalocyanine pigments and metal-free metal cyanine pigments, quinone pigments such as anthrone and pyranthrone, quinacridone pigments, bisbenzimidazole pigments, perylene pigments, Known organic pigments such as indigo pigments, squalium pigments, quinoline pigments, biryllium salt pigments, and azulenium salt pigments can be used. Among these charge-generating substances, azo pigments are particularly preferred, and among azo pigments, the following disazo pigments and trisazo pigments are most preferred. Specific examples of azo pigments are shown below. Face 41 Kiichi 111 Shi 111 "O Face" 1 Shame 11 - Ko L 111 Face 4k Ki 11 - A 11 1 Hire" L Ki 111 JL 111 Face 41 Kanichi 02 face JL & 111ko ν111 face 41 change ---ko V111 face' L encouragement ^ 1 face 41 encouragement 1 convex face 41 encouragement = convex E face 41 shame 11 - ko [1 11 face 4L excitation = 62 face 41 excitation 8e face 4L fusion 11 - ko [-11 face 41 excitation = 82 group 4 [transition 1-1 Δ-11 These charge-generating substances are singly Alternatively, two or more types can be used in combination. The charge generation layer can be formed by dissolving or dispersing a resin binder and a charge generation substance in a suitable solvent, applying the solution, and drying it. As a solvent, benzene, toluene, xylene, methylene chloride, dichloroethane, monochlorobenzene, dichlorobenzene, ethyl acetate, butyl acetate, methyl ethyl ketone, dioxane, tetrahydrofuran, cyclohexanone, methyl cellosolve, ethyl cellosolve, etc. can be used alone or in combination. can.

The thickness of the charge generation layer is suitably 0.05 to 5 pm, preferably 0.1 to 2.0 pm. The binder resin is suitably used in an amount of 0 to 50 parts by weight, preferably 0 to 10 parts by weight, per 1 part by weight of the charge generating substance. Further, a charge transport substance may be contained in the charge generation layer.

The charge transport layer can be formed by dissolving or dispersing a charge transport substance, a binder resin, etc. in a suitable solvent, coating the solution, and drying the solution. Moreover, a plasticizer and a leveling agent can also be added if necessary.

As the charge transport substance, poly N-vinyl Rubazole and its derivatives, poly γ-carbazolylethyl glutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives are used. , imidazole derivatives, triphenylamine derivatives, 9-(p-diethylaminostyryl)anthracene, 1,1-bis(4-dibenzylaminophenyl)propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene Examples include electron-donating substances such as derivatives.

In particular, aromatic aminated compounds represented by the following general formula (1) are preferred.

basis, naphthyl group, and polyphenyl groups. aromatic ring group, or a heteroaromatic group shows, R3 is substitution, unsubstituted aryl group, Al vinegar.

Typical specific examples of aromatic amine compounds represented by general formula (1) are listed below. uko1, 11, L, υ shiN3 shi■1 +411s 1.2 1+, 1-atls shin3 shiII, Ll These charge transport substances are. They may be used alone or in combination of two or more.

As the solvent used in preparing the charge transport layer coating solution, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, etc. can be used.

The thickness of the charge transport layer is 5 to 100 mm. The degree is appropriate.
Furthermore, the binder resin is 0.0% per part by weight of the charge transport material.
The amount is preferably 5 to 5 parts by weight. Binder resins that can be used in the charge generation layer and the charge transport layer include polystyrene, styrene-acrylonitrile copolymer,
Styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyacrylate resin, phenoxy resin,
Polycarbonate, cellulose acetate, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal,
Polyvinyltoluene, Poly N-vinyl Rubazole,
Examples include thermoplastic or thermosetting resins such as acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin. If necessary, a subbing layer with charge blocking and adhesive functions can be provided between the conductive support and the photosensitive layer. The undercoat layer, which is provided as needed, generally has a resin as its main component, but considering that the photosensitive layer is coated on top of it with a solvent, these resins are resistant to solubility in general organic solvents. It is desirable that the resin has a high Such resins include polyvinyl alcohol, casein, water-soluble resins such as sodium polyacrylate, copolymerized nylon,
Alcohol-soluble resins such as methoxymethylated nylon,
Examples include curable resins that form a three-dimensional network structure, such as polyurethane, melamine resin, phenol resin, and epoxy resin. Further, fine powder pigments of metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the undercoat layer to prevent moire and reduce residual potential.

Methods for forming the photosensitive layer include immersing the conductive support in a coating solution for the charge generation layer, charge transport layer, and intermediate layer, and spraying the coating solution onto the substrate. The conductive support used in the electrophotographic photoreceptor of the present invention includes metal drums and sheets made of aluminum, brass, stainless steel, nickel, etc., materials such as polyethylene terephthalate, polypropylene, nylon, paper, and metals such as aluminum and nickel. Examples include sheet-like or cylindrical substrates made of plastic, paper, etc., which have been treated to be conductive by vapor deposition or by coating a conductive substance such as titanium oxide, tin oxide, or carbon black with a suitable inder.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Alcohol-soluble polyamide (Amilan CM-8000
; Toray Industries II) 1 part by weight, 8 parts by weight of methanol and n-
It was dissolved in a mixed solvent containing 5 parts by weight of butanol. Add titanium oxide powder (Tipaque A-1σO, manufactured by Ishihara Sangyo Co., Ltd.) 3
Parts by weight were added and dispersed in a ball mill for 12 hours to prepare a coating solution for an undercoat layer. This has a major diameter of φ40 and a length of 255ma.
Coated on + aluminum drum using dip coating method, 130℃
It was dried for 20 minutes to form a 2-thick subbing layer.

Next, polyvinyl butyral resin (S-LEC BL-S:
Sekisui Chemical Co., Ltd.) 5 parts by weight of cyclohexanone 150
10 parts by weight of a trisazo pigment represented by the following structural formula (n) was added thereto and dispersed in a ball mill for 48 hours, and further 210 parts by weight of cyclohexanone was added and dispersed for 3 hours. Take this out into a container, and the solid content is 1.
It was diluted with cyclohexanone to a concentration of 5% by weight. The charge generation layer coating solution thus obtained was applied onto the undercoat layer by dip coating, and dried at 130°C for 20 minutes to a thickness of 0.2 μm.
A charge generation layer was formed. Next, polycarbonate resin (Panlite K-1300;
(manufactured by Teijin Chemicals) 10 parts by weight, silicone oil (KF-5
0; Shin-Etsu Chemical Co., Ltd.! ! ) was dissolved in 83 parts by weight of methylene chloride, and 9 parts by weight of a charge transport substance represented by the following structural formula (m) was added and dissolved to prepare a charge transport layer coating solution. This was coated by dip coating on the charge generation layer and dried at 130°C for 20 minutes to form a charge transport layer with a thickness of 20 mm. ■ KoshiNext, 15 parts by weight of an alcohol-soluble phenol resin (Priorfen SOIO; manufactured by Dainippon Ink and Chemicals) was dissolved in 85 parts by weight of a mixed solvent of methanol In-butanol = 8/2 (weight ratio), and the charge transport layer was It was applied by dip coating on top and dried for 30 minutes at 130°C to form an intermediate layer with a thickness of 0.34 mm. Finally, apply 120% of the protective layer coating solution shown below on this intermediate layer.
Disperse in a ball mill for an hour, apply the dispersion, and
The electrophotographic photoreceptor of Example 1 was prepared by drying at 0° C. for 1 hour and forming a protective layer of 5lIIA. [Protective layer coating liquid] Resistance control agent SnO, (Sb, O, dove) fine powder (
Mitsubishi Metals T-1) 13 parts polyol-curing urethane resin 53 parts hexamethylene diisocyanate 1 part methyl ethyl ketone
46 parts Example 2 The resin for the intermediate layer was an alcohol-soluble phenol resin (Pryophen J-325; manufactured by Dainippon Ink and Chemicals Co., Ltd.)
An electrophotographic photoreceptor of Example 2 was prepared in the same manner as in Example 1 except that . Comparative Examples 1 to 3 Alcohol-soluble polyamide (Amilan-CM8000
; Toray Industries ml), nylon resin (AQ-nylon C-8
0: manufactured by Toray Industries), nylon resin (AQ-Nylon A-7
0: manufactured by Toray Industries, Inc.) 3 parts by weight of each were dissolved in 97 parts by weight of a mixed solvent (methanol/n-butanol = IS/2 weight ratio) and coated on the charge transport layer and dried at 130°C for 20 minutes to a thickness of 0.
．． 3. Electrophotographic photoreceptors of Comparative Examples 1, 2, and 3 were prepared in the same manner as in Example 1, except that the intermediate layer was formed. The electrophotographic photoreceptor obtained as described above was mounted on a laser printer (PC-LASER-6000; Ricoh All Co., Ltd.), and image copying and electrostatic properties were evaluated at 23° C. and 730% RH. ．． The surface potential was measured by removing the developer and attaching a surface electrometer probe to the development position. The results are shown in Table-1.

The results of surface resistance measurements measured using the method described in the specification are also shown. Further, as a reference example, in Example 1, an electrophotographic photoreceptor without an intermediate layer and a resistive protective layer was also evaluated in the same manner. Table 1 also includes the results.
It was described in Ning 1 Image evaluation: O...The image is clear with no blurring.×...The text image appears, but the image is noticeably blurred. As is clear from the above results, the surface resistance of the intermediate layer is 10
If it is 1 sΩ or more, a good image is obtained without blur. In addition, the image blurring of the photoreceptor of the comparative example worsens even under high temperature and high humidity conditions (30° C. and 90% RH), but the electrophotographic photoreceptor of the present invention shows good images without image blurring even under high temperature and high humidity conditions. Ta. 〔effect〕

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor in which at least a charge generation layer, a charge transport layer, an intermediate layer, and a protective layer are sequentially laminated on a conductive support, the intermediate layer has a surface resistance of 10^1^5 Ω or more, and An electrophotographic photoreceptor characterized by containing an alcohol-soluble resin as a main component. (2) The electrophotographic photoreceptor according to claim 1, wherein the alcohol-soluble resin is a phenol resin.