JPH0675209B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor. In particular, the present invention relates to an electrophotographic photoreceptor that uses an anodized film that has been subjected to a specific treatment.

[Conventional technology]

An image forming system using an electrophotographic system is widely applied to the field of copying, and various excellent 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 it is desired to improve the function of a so-called printer that prints out these data. Therefore, the use of an electrophotographic printing system in this field has been studied and put into practical use. Has been done. That is, the data of the electric signal is converted to the laser scanner, LED
By means of an array or liquid crystal shutter,
It is a process of converting into an optical signal, irradiating the photoconductor, forming a latent image on the photoconductor, visualizing it by toner development, and obtaining an image, which is also called an optical printer. This method has a much faster printing speed than the conventional impact method,
Moreover, it is rapidly becoming popular because it is capable of high-quality printing without noise.

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 the output wavelength of the semiconductor laser. Organic photoconductors, which are relatively easy to have sensitivity in the near infrared region, are extremely suitable, and various materials have been developed. In particular, the layered organic photoconductor consisting of the charge generation layer and the charge transfer layer makes full use of the abundance of organic compounds, and it is possible to obtain a photoreceptor with high sensitivity and high printing durability, and it is also safe. In terms of the above, it is also extremely useful in that a pollution-free material can be selected.

As an image forming method in an optical printer, a reversal developing method is often employed in which toner is attached to a portion irradiated with light to form an image for the purpose of effectively utilizing light or increasing resolution. In the reversal development method, the dark potential part becomes a white background and the light potential part becomes a black background part (image area).
In this system, if there is a local charging defect due to a defect or the like on the photosensitive member, black spots on a white background or a large number thereof cause development such as background fog, which results in a marked image defect.

Even if such a local electrification defect does not cause any problems when used in regular development, it tends to result in an image defect in reversal development. To some extent,
It turns out that there are problems with black dots and fog.

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

As such a blocking layer, aluminum oxide, an inorganic layer such as aluminum hydroxide, polyvinyl alcohol,
Resin layers such as casein, sodium caseinate, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide and polyamide are used.

[Problems to be Solved by the Invention]

However, if these conventional photoreceptors having a blocking layer are used in the process of the reversal development system, it is difficult to completely eliminate the black spots, and the background fog becomes remarkable especially under high humidity environmental conditions. Further, when it is repeatedly used under a low humidity, the black ground potential remarkably rises, which often cannot be put to practical use, and further improvement is desired.

Among the blocking layers known so far, the sealing-processed anodic oxide film formed on the aluminum substrate has relatively small environmental dependence of electrical characteristics and shows good characteristics. When used in a developing process, image defects such as spots or flow patterns appear remarkably under high temperature and high humidity, and it is currently difficult to obtain a product that can be used practically.

[Means for Solving the Problems]

The inventors of the present invention have been keen to solve the problems such as background fog and minute black spots of an electrophotographic photosensitive member using an aluminum substrate having an anodic oxide coating, which is used in the process of the reversal development method as described above. As a result of the examination, by using a substrate that has been subjected to a specific post-treatment after anodizing the aluminum substrate in the process of forming the anodized film, under a wide environmental condition including high humidity, background fog and other image defects It was found that a photoconductor having good characteristics can be obtained without the occurrence of the above problems, and the present invention has been accomplished.

That is, the gist of the present invention is that, in an electrophotographic photosensitive member having a photosensitive layer provided on an aluminum substrate having an anodic oxide coating, the anodic oxide coating is subjected to sealing treatment, and then immersed in hot water at 80 ° C. or higher. An electrophotographic photosensitive member characterized by being a coated film.

Hereinafter, the present invention will be described in detail.

The aluminum used as the substrate in the present invention is not limited to pure aluminum as long as it is suitable for the use of the present invention, and an aluminum alloy can also be used.

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

The anodized film is usually formed by anodizing in an acidic bath of chromic acid, sulfuric acid, oxalic acid, boric acid, sulfamic acid, etc., but anodizing in sulfuric acid gives the best results. give. In the case of anodizing in sulfuric acid, the sulfuric acid concentration is 100 to 300 g / l, the dissolved aluminum concentration is 2 to 15 g / l, the liquid temperature is 15 to 30 ° C, the electrolysis voltage is 5 to 20 V,
The current density should be set in the range of 0.5-2 A / dm ² .
Average thickness of anodized film is usually less than 20μm, especially 7μm
It is preferably formed as follows.

The anodic oxide film thus formed is subjected to a sealing treatment.

The sealing treatment may be a commonly used method, preferably a low temperature sealing treatment in which it is immersed in an aqueous solution containing nickel fluoride as a main component, or a high temperature sealing treatment in which it is immersed in an aqueous solution containing nickel acetate as a main component. Processing is mentioned as an example.

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.

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 a nickel acetate aqueous solution is used, the concentration is preferably within the range of 3 to 20 g / l. Processing temperature is 65-100
℃, preferably 80 ~ 98 ℃, the pH of 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 preferably 10 minutes or longer, and particularly preferably 20 minutes or longer. Also in this case, sodium acetate, an organic carboxylate, an anionic surfactant, a nonionic surfactant, etc. may be added to the nickel acetate aqueous solution in order to improve the physical properties of the coating.

The sealing-processed anodized film formed as described above is usually washed subsequently with water and then subjected to the hot water immersion treatment according to the present invention.

As hot water immersion treatment conditions, it is preferable to carry out the immersion treatment in hot water of 80 ° C. or higher, preferably 90 ° C. or higher for usually 5 minutes or longer, preferably about 7 to 30 minutes.

If the anodic oxide coating is used as it is, it has poor weather resistance because it is porous, and corrosion or the like occurs. Therefore, a treatment for sealing those pores, that is, a sealing treatment is usually performed. This sealing treatment, when using an aqueous solution of heavy metal salts as described above, is advantageous and effective in production as compared with other water vapor sealing, but on the other hand, heavy metal salts and other foreign substances are not present on the coating surface. It has the drawback of sticking easily.

On the other hand, in the manufacturing method of the present invention, after the sealing treatment,
It was found that such a fixed substance can be eluted and removed by the hot water immersion treatment, and that the high temperature treatment of 80 ° C or higher has the effect of promoting the sealing.

Therefore, by carrying out a hot water immersion treatment after the usual sealing treatment, the sealing treatment conditions can be made mild and a well-sealed clean anodized film can be obtained. The hot water used in the present invention does not necessarily need to be pure water, and a water-soluble solvent such as alcohol may be mixed to the extent that the effect of the present invention is not impaired.

As the photosensitive layer provided on the anodic oxide coating formed as described above, various inorganic and organic photoconductive layers can be used. However, a laminated photoconductor including a charge generation layer and a charge transfer layer can be used. It is extremely useful when used.

In this case, as the charge generation layer, inorganic photoconductors such as Se and its alloys, arsenic-selenium, and cadmium sulfide; various organic pigments such as phthalocyanine, azo dye, quinacridone, and polycyclic quinone can be used. Especially metal-free phthalocyanine,
Metals such as copper, indium chloride, gallium chloride, tin, oxytitanium, zinc, vanadium or oxides thereof;
Azo pigments such as chloride-coordinated phthalocyanines, monoazo, bisazo, trisazo, polyazos are preferred.

The charge generation layer is generally formed as a uniform layer of these substances or in the state where these substances are dispersed as fine particles in the 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.

As the charge transfer material used for the charge transfer layer, polymer compounds such as polyvinyl, carbazole, 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 binder resins include polymethylmethacrylate, polystyrene, vinyl polymers such as polyvinyl chloride and copolymers thereof, polycarbonate, polyester, phenoxy, epoxy, silicone resins, and the like, and also partially cross-linked cured products thereof. 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 40 μm, preferably 13 to 25 μm.

The electrophotographic photoreceptor of the present invention obtained as described above can be used in an electrophotographic system such as a reversal development system.

〔Example〕

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

Examples and Comparative Examples An aluminum cylinder having a mirror-finished surface and a thickness of 1 mm was degreased and washed in a 30 g / l aqueous solution of a degreasing agent NG- # 30 (manufactured by Kizai Co., Ltd.) at 60 ° C. for 5 minutes. Then, after washing with water, it was immersed in 7% nitric acid at 25 ° C. for 1 minute. After washing with water, 180g / l sulfuric acid electrolyte (dissolved aluminum concentration 7g / l
In step 1), anodization was performed at a current density of 1.2 A / dm ² to form an anodized film having an average film thickness of 8 μm.

Then, after washing with water, a high-temperature sealing agent Sealing Z containing nickel acetate as a main component (Hanami Kagaku Co., Ltd.)
The plate was immersed at 24 ° C. for 24 minutes for sealing treatment.

Then, after washing with water, it was immersed in a pure water bath at 95 ° C. for 12 minutes for hot water treatment.

On the other hand, 10 parts by weight of oxytitanium phthalocyanine and 5 parts by weight of polyvinyl butyral (Sekisui Chemical Co., Ltd., trade name Eslec BH-3) were added with 500 parts by weight of 1,2-dimethoxyethane and pulverized with a sand grind mill and dispersed. It was

To this dispersion, an aluminum cylinder provided with an anodized film formed earlier is applied by dip coating, and the film thickness after drying is 0.4.
The charge generation layer was provided so as to have a thickness of μm.

Next, this aluminum cylinder is
56 parts by weight14 parts by weight of the hydrazone compound shown below,1.5 parts by weight of cyano compoundAnd polycarbonate resin (Made by Mitsubishi Kasei Co., Nobare
X 7030A) 100 parts by weight of 1,4-dioxane 1000 parts by weight
The film thickness is 17μm after being applied by dipping in a liquid
The charge transfer layer was provided so that

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

For comparison, a photosensitive member B was prepared in the same manner as the photosensitive member A except that the sealing member was rinsed, rinsed with water and dried without performing hot water treatment at 95 ° C. for 12 minutes.

Next, these photoreceptors were mounted on a commercially available reversal development type laser printer, and the image characteristics under each environment were evaluated.

As a result, with the photoconductor A, (1) 5 ° C., 10% RH, (2)
Under both environmental conditions of 25 ° C, 60% RH, (3) 35 ° C, 85% RH, good images were obtained on both white and black backgrounds. Under environmental conditions, many white image defects appeared on the white background image, and a good image was not obtained.

From the above results, it can be judged that the electrophotographic photosensitive member according to the production method of the present invention has excellent performance.

〔The invention's effect〕

The electrophotographic photosensitive member of the present invention exhibits good characteristics without image defects under a wide range of environmental conditions including high humidity, and can be suitably used in a reversal development type electrophotographic process. Therefore, the present invention is extremely useful industrially.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer provided on an aluminum substrate having an anodized film, the anodized film being subjected to a pore-sealing treatment and then immersed in hot water at 80 ° C. or higher. An electrophotographic photosensitive member characterized by being a coated film.