JPH07120062B2 - Electrophotographic photoreceptor - Google Patents

Description

The present invention relates to an electrophotographic photosensitive member, and more particularly to an electrophotographic photosensitive member suitable for use in a reversal development type process.

[Conventional technology]

An image forming system using an electrophotographic system has been widely applied to the field of copying, and various inorganic and organic photoconductors have been developed as photoconductors used in the system.

On the other hand, recently, the digital signal data processing system has advanced and spread, and the function of a so-called printer that prints out these data is also desired to be improved. The use of an electrophotographic printing system in this field has been studied and put into practical use. Has been done.

These convert electrical signal data into optical signals by means of laser scanners, light emitting diode (LED) arrays, liquid crystal shutters, etc., irradiate the photoconductor, form a latent image on the photoconductor, and develop toner. It is a process of visualizing and obtaining an image, and is also called an optical printer.

Compared with the conventional impact type, this type has an extremely high printing speed, is free from noise, and is capable of high-quality printing, and is rapidly spreading.

Se, CdS are used as photoconductors for such optical printers.
Inorganic photoconductors such as, and organic photoconductors such as charge transfer complexes of polyvinylcarbazole and trinitrofluorenone have been used, but it is easy to select the photosensitive wavelength range, especially in the output wavelength range of the semiconductor laser. Organic photoconductors, which are relatively easy to have sensitivity in a certain near infrared region, are extremely suitable, and various materials have been developed. In particular, the laminated organic photoconductor formed by laminating the charge generation layer and the charge transfer layer makes full use of the abundance of types of organic compounds, and a high-sensitivity and high printing durability photoreceptor has been obtained. Also, in terms of safety, you can select non-polluting materials,
Extremely useful.

On the other hand, as an image forming method in an optical printer, a so-called reversal development method in which a toner is adhered to a portion irradiated with light to form an image is often employed for the purpose of effectively utilizing light or increasing resolution.

In the reversal development process, the dark potential part becomes a white background,
The bright potential part becomes a black background part (image area), but in this system, if there is a local charging failure due to a defect on the photoconductor, black spots on a white background or development such as background fog if there are many And appears as a marked image defect.

Such a local electrification defect is liable to cause an image defect in reversal development even when it is at a level such that it does not cause any problem when used in regular development, and moreover, it is a laminated system obtained in the past. It has been found that the photoconductor has problems with black spots and fog to some extent.

Various causes can be considered for the cause of this problem, that is, local electrification failure, but it is considered that the injection of charges locally occurs between the conductive support that is the electrode and the photosensitive layer, and the charging potential does not rise. Conceivable. In order to improve this, it is conceivable to provide a blocking layer between the conductive support and the photosensitive layer.

Providing such a blocking layer is known as a conventionally known technique, and its material is an inorganic layer such as aluminum oxide or aluminum hydroxide, polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, Resin layers such as gelatin, starch, polyurethane, polyimide, polyamide are used.

[Problems to be Solved by the Invention]

However, even if the photoreceptor having these conventional blocking layers is used in the process of the reversal development method, it is difficult to completely eliminate the black spots, and particularly, the background fogging is remarkable under the environmental conditions of high humidity, In many cases, it cannot be put to practical use, and further improvement has been desired.

[Means for Solving the Problems]

Therefore, as a result of diligent studies, the inventors of the present invention have conducted a diligent study to solve the problems such as background fogging and microscopic black spots of the electrophotographic photosensitive member used in the process of the reversal development method. It has been found that a photosensitive member having good image characteristics and electric characteristics without background fog can be obtained under a wide range of environmental conditions including low humidity and high humidity by using an aluminum base material having the above-mentioned characteristics.

That is, the gist of the present invention is to provide an electrophotographic photosensitive member comprising a photoconductive layer having at least a 0.1 to 1 μm-thickness charge generation layer and a charge transfer layer laminated in this order on an aluminum substrate having an anodized film. When the anodic oxide coating is subjected to sealing treatment, the average film thickness of the anodic oxide coating is d, and the admittance obtained by the following measurement method is Ym,
An electrophotographic photosensitive member is characterized in that Ym × d is 4 × 10 ⁻¹⁰ (S · m) or less.

[Measurement method of admittance]

Internal area of 133 mm ² on the coating surface of the sample in the environment of 25 ℃
After attaching the non-conductive electrolysis cell of No. 3 for 3.5 minutes to the electrolytic cell and leaving it for 30 minutes, connect one end of the electrode of the admittance measuring instrument to the substrate and insert one electrode into the test solution. Then, measure at a frequency of 1 kHz.

Hereinafter, the present invention will be described in detail.

The photoconductor of the present invention has a photoconductive layer provided on an aluminum substrate having a specific anodized film.

The aluminum substrate is preferably degreased by various degreasing cleaning methods such as acid, alkali, organic solvent, surfactant, emulsion and electrolysis before anodizing treatment.

The anodic oxide coating is formed by a conventional method, for example, chromic acid, sulfuric acid,
In an acidic bath of oxalic acid, boric acid, sulfamic acid, etc.,
It is formed by anodizing, but anodizing in sulfuric acid gives the best results. In the case of anodizing in sulfuric acid, sulfuric acid concentration is 100 ~ 300g / l, dissolved aluminum concentration is 2 ~ 15g / l, liquid temperature is 15 ~ 30 ℃, electrolysis voltage is 10
The current density is preferably set to -20 V and the current density is set to 0.5-2 A / dm ² , but the present invention is not limited to this.

A sealing treatment is performed on the anodized film thus formed. The sealing treatment method may be an ordinary method, for example, low temperature sealing treatment by immersing in an aqueous solution containing nickel fluoride as a main component, or high temperature sealing treatment by immersing in an aqueous solution containing nickel acetate as a main component. Is preferably applied.

The concentration of the nickel fluoride aqueous solution used in the case of the low-temperature sealing treatment can be appropriately selected, but it is most effective when it is used in the range of 3 to 6 g / l.

In order to smoothly proceed the sealing treatment, the treatment temperature is 25 to 40 ° C, preferably 30 to 35 ° C, and the pH of the nickel fluoride aqueous solution is 4.5 to 6.5, preferably 5.5 to 6.0. Is good. As the pH adjusting agent, oxalic acid, boric acid, formic acid, acetic acid, sodium hydroxide, sodium acetate,
Ammonia water or the like can be used. The treatment time is preferably within a range of 1 to 3 minutes per 1 μm of the film thickness.

In order to further improve the physical properties of the coating, cobalt fluoride, cobalt acetate, nickel sulfate, a surfactant, etc. may be added to the nickel fluoride aqueous solution. Then, it is washed with water and dried to complete the low-temperature sealing treatment.

As the sealing agent in the case of the high-temperature sealing treatment, nickel acetate, cobalt acetate, lead acetate, nickel acetate-cobalt,
An aqueous solution of a metal salt such as barium nitrate can be used, but nickel acetate is particularly preferably used.

When using an aqueous nickel acetate solution, the concentration is preferably within the range of 5 to 20 g / l. Processing temperature is 80-100
℃, preferably 90 ~ 98 ℃, the pH of the nickel acetate aqueous solution
Should be processed in the range of 5.0 to 6.0. Ammonia water, sodium acetate or the like can be used as the pH adjuster.

The treatment time is 10 minutes or longer, preferably 20 minutes or longer. Also in this case, sodium acetate, an organic carboxylate, an anionic surfactant, a nonionic surfactant and the like may be added to the nickel acetate aqueous solution in order to improve the physical properties of the coating. Then, it is washed with water and dried to complete the high-temperature sealing treatment.

The admittance of the film formed as described above can be measured in the following manner in the present invention.

Internal area of 133 mm ² on the coating surface of the sample in the environment of 25 ℃
Attach the non-conductive electrolysis cell of, and fill the electrolysis cell with a 3.5 wt% potassium sulfate aqueous solution. After leaving it for 30 minutes, connect one end of the electrode of a commercially available admittance measuring instrument to the substrate,
Insert one electrode into the test solution and measure the admittance Ym at a frequency of 1 KHz.

Here, in order to obtain a film having Ym × d of 4 × 10 ⁻¹⁰ (S · m) or less, it can be obtained by adjusting either the sealing condition or the film thickness, or both, but the average film thickness is large. In this case, in order to obtain the same Ym × d value, stronger sealing conditions are required such as increasing the concentration of the sealing liquid and treating at high temperature for a long time. Therefore, the productivity is deteriorated, and surface defects such as stains, stains, and dusts are likely to occur on the coating surface.

From this point of view, the average thickness of anodized film is usually 20μ.
The thickness is preferably m or less, particularly preferably 7 μm or less.

As the photoconductive layer provided on such an anodized film, various inorganic and organic photoconductive layers can be used, but in the case of using a laminated photoconductor including a charge generation layer and a charge transfer layer, Extremely useful.

The charge generation layer in this case includes a known charge generation material such as Se and its alloys, arsenic-selenium, cadmium sulfide,
Other inorganic photoconductors, phthalocyanines, azo dyes, quinacridones, various organic pigments such as polycyclic quinones can be used. Among them, metal-free phthalocyanines, copper, indium chloride, gallium chloride, tin, oxytitanium, zinc, vanadium, and other metals or their oxides, phthalocyanines coordinated with chlorides; azo such as monoazo, bisazo, trisazo, polyazos Pigments are preferred.

The charge generation layer is formed as a uniform layer of these charge generation materials or in a state where fine particles are dispersed in a binder resin. Examples of the binder resin used here include phenoxy, epoxy, polyester, acrylic, polyvinyl butyral, and polycarbonate resins. The film thickness is usually 0.1 to 1 μm, preferably 0.15 to
0.6 μm is preferable.

As the charge transfer material in the charge transfer layer, polymer compounds such as polyvinylcarbazole, polyvinylpyrene, polyacenaphthylene, and low molecular compounds such as various pyrazoline derivatives, oxazole derivatives, hydrazone derivatives, and stilbene derivatives can be used. A binder resin is blended with these charge transfer materials as needed. Preferred binders include polymethylmethacrylate,
Examples thereof include vinyl polymers such as polystyrene and polyvinyl chloride and copolymers thereof, polycarbonate, polyester, phenoxy, epoxy, silicone resin, and the like, and partially cross-linked cured products thereof are also used.

Further, the charge transfer layer may contain various additives such as an antioxidant and a sensitizer, if necessary.

The thickness of the charge transfer layer is usually 10 to 30 μm, preferably 13 to 25
It is better to use with a thickness of μm.

〔The invention's effect〕

When the electrophotographic photosensitive member obtained by the present invention is used in an electrophotographic system including a reversal development type process,
Good images without fog can be obtained under a wide range of environmental conditions including high humidity.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

Production Example-1 An aluminum cylinder having a mirror-finished surface with a thickness of 1 mm was placed in a 30 g / l aqueous solution of a degreasing agent Top Alclean 160 (trade name, manufactured by Okuno Chemical Industries Co., Ltd.) at 60 ° C for 5 minutes. It was degreased and washed. After washing with water, 7%
It was immersed in nitric acid at 25 ° C for 1 minute. After washing with water, anodic oxidation was performed at a current density of 1.0 A / dm ^{2 in} a 180 g / l sulfuric acid electrolytic solution (dissolved aluminum concentration 7 g / l) to form an anodic oxide coating having an average film thickness of 6 μm. In addition, this average film thickness is the electromagnetic film thickness meter Permas.
cope (permascope) (trade name, manufactured by Fisher)
The film thickness is measured at 20 points on the cylinder by means of and averaged (the same method is used hereinafter).

Next, after washing with water, a high-temperature sealing agent with a main component of nickel acetate, Topseal DX-500 (trade name, manufactured by Okuno Chemical Industry Co., Ltd.)
It was immersed in a 10 g / l aqueous solution at 95 ° C. for 18 minutes for sealing treatment. Then, it was thoroughly washed with pure water and dried.

When the admittance of this coating was measured, it was 41 μS. Further, Ym × d was 2.46 × 10 ⁻¹⁰ (S · m).

On the other hand, to 10 parts by weight of oxytitanium phthalocyanine and 5 parts by weight of polyvinyl butyral (Sekisui Chemical Co., Ltd., trade name Eslec BH-3), add 500 parts by weight of 1,2-dimethoxyethane, and grind and disperse with a sand grind mill. Was done.

An aluminum cylinder previously provided with an anodic oxide coating was applied by dip coating to this dispersion, and a charge generation layer was provided so that the film thickness after drying was 0.4 μm.

Next, this aluminum cylinder, the hydrazone shown below
56 parts by weight of compound,14 parts by weight of the hydrazone compound shown below,1.5 parts by weight of the following cyano compoundsAnd polycarbonate resin (manufactured by Mitsubishi Kasei Co., Ltd.
Barex 7030A) 100 parts by weight of 1,4-dioxane 1,000
Dry by applying by dipping in a solution dissolved in parts by weight
A charge transfer layer was provided so that the subsequent film thickness would be 17 μm.

The drum thus obtained is hereinafter referred to as a photoconductor A.

Production Examples-2 to 5 Photosensitization was performed in the same manner as in Production Example 1 except that the film thickness of the coating, the concentration of the high-temperature sealing liquid, the temperature, and the treatment time were changed as shown in Table 1 in the formation of the anodic oxide coating. Created bodies B-E. The Ym × d of these anodized films was as shown in Table 1.

Production Example 6 An aluminum cylinder having a mirror-finished surface and a thickness of 1 mm was degreased and washed in a 50 g / l aqueous solution of a degreasing agent P ₃ T-580S (trade name, manufactured by Henkel Hakusui Co., Ltd.) at 60 ° C. for 5 minutes. Then, after washing with water, anodic oxidation was performed at a current density of 1.2 A / dm ² in 170 g / l sulfuric acid electrolyte (dissolved aluminum concentration 6 g / l) to form an anodized film with an average film thickness of 5.5 μm. did.

Then, after rinsing with water, it was immersed in a 5 g / l aqueous solution of nickel fluoride fluoride-based sealing agent hard wall No. 5 (manufactured by Nichika Chemical Industry Co., Ltd.) adjusted to pH 6.0 with acetic acid at 35 ° C. for 5 minutes. , Sealing treatment was performed. Then, it was thoroughly washed with pure water and dried. The Ym x d of this film is 1.26 x 10
^{It was -10} ( ^Sm ).

After that, a charge generation layer and a charge transfer layer were sequentially applied and dried in the same manner as in Production Example 1 to prepare a photoconductor F.

Comparative Production Examples-1 to 3 The procedure of Production Example-1 was repeated except that the film thickness of the coating, the concentration of the sealing liquid, the treatment temperature, and the treatment time were changed as shown in Table 2 in the formation of the anodic oxide coating. , Photoconductors G, H, and I were prepared. The Ym × d of these anodized films was as shown in Table-2.

Examples 1 to 6 and Comparative Examples 1 to 3 Photoreceptors A to I were mounted on a commercially available copying machine modified for reversal development, and image characteristics were evaluated under each environmental condition. The results are shown in Table-3, the photoreceptor A, B, C, D, E, F, G of the present invention
In each case, a good image without fog and fine black spots was obtained under any of the conditions.However, in each of the photoconductors of Comparative Examples, bad fog occurs especially under high temperature and high humidity, which is not practical. I knew it was.

As is clear from the above results, it was confirmed that the electrophotographic photosensitive member using the specific anodic oxide coating of the present invention showed good image characteristics and had excellent performance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Minoru Masuda 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryo Kasei Kogyo Co., Ltd. (56) Reference JP-A-54-89637 (JP, A) Kai 61-263490 (JP, A) JP-A 61-263349 (JP, A)

Claims (1)

[Claims] 1. An electrophotographic photosensitive member comprising a photoconductive layer having a film thickness of 0.1 to 1 μm and a charge transfer layer laminated in this order on an aluminum substrate having an anodized film. When the anodic oxide coating is subjected to sealing treatment, and the average film thickness of the anodic oxide coating is d and the admittance obtained by the following measurement method is Ym, Ym × d is 4
An electrophotographic photosensitive member characterized by having a density of not more than × 10 ⁻¹⁰ (S · m). [Measurement method of admittance] The internal area of 133 mm ²
After attaching the non-conductive electrolysis cell of No. 3, and leaving it for 30 minutes while filling the electrolysis cell with 3.5 wt% potassium sulfate aqueous solution, connect one end of the electrode of the admittance measuring instrument to the substrate, and use one of the electrodes as the test solution. Insert and measure at a frequency of 1kHz.