JP2718066B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member. More specifically, the present invention relates to an electrophotographic photosensitive member provided with an anodic oxide film layer and an undercoat layer.

(Prior Art) An image forming system using an electrophotographic method has been widely applied in the field of copying from the past. In recent years, digital signal data processing systems have advanced and spread, and the function of a so-called printer that prints and outputs these data has been desired to be improved. ing.

As photoreceptors used in these systems, inorganic photoreceptors such as selenium, arsenic-selenium alloy, cadmium sulfide, and amorphous silicon, and charge transfer complexes of polyvinyl carbazole and trinitrofluorenone have been used. Organic photoreceptors are extremely suitable for this kind of applications because of the ease of selection of the photosensitive wavelength region, and in particular, the relative ease of having sensitivity in the near-infrared region, which is the output wavelength region of a semiconductor laser, Materials are being developed.

In particular, a laminated organic photoreceptor composed of a charge generation layer and a charge transfer layer makes full use of the diversity of organic compounds, and provides a photoreceptor with high sensitivity and high printing durability. However, it is extremely useful because non-polluting materials can be selected.

The photosensitive layer used here is usually provided on a conductive substrate such as aluminum, but if there are minute scratches, defects, or stains on the substrate surface, it may cause image defects such as white stripes and black spots. Or cause deterioration of electrical characteristics such as chargeability and sensitivity.

As one of means for improving such non-uniformity of the substrate surface, it is conventionally known to provide an undercoat layer on the substrate surface. Specific materials for the undercoat layer include polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, polyamide, phenolic resin, and the like.

(Problems to be Solved by the Invention) However, photoreceptors using these materials for the undercoat layer are:
When used repeatedly or when used under low humidity, there is a problem that the residual potential tends to increase.

In addition, when used in a reversal development system often used in so-called optical printers using laser light or emitting diode light as a light source, minute defects on the substrate surface are more likely to appear more noticeably as black spots and background fog. Even if a layer is provided, it is difficult to completely eliminate the layer, and it is often unpractical, and further improvement is desired.

On the other hand, as another means for improving the non-uniformity of the substrate surface, it is well known that anodizing is applied to an aluminum substrate to provide an alumite coating.

By providing the alumite coating, most of the minute defects such as dirt and deposits on the aluminum substrate can be eliminated.

In addition, the alumite surface has advantages that it is harder than aluminum and is less likely to be damaged, and that the adhesion to the photosensitive layer is improved.

However, on the other hand, the alumite film is usually formed by an aqueous treatment process such as electrolysis in a sulfuric acid aqueous solution, sealing with a heavy metal salt aqueous solution, and subsequent washing with water. At present, it is quite difficult to obtain a sufficiently clean coating.

(Means for Solving the Problems) In view of the problems of the electrophotographic photoreceptor, the inventors of the present invention have shown that in order to obtain a substrate surface having excellent environmental stability and exhibiting more uniform and sufficient cleanliness. As a result of diligent studies, it has been found that by providing an anodic oxide film on an aluminum substrate and further providing an undercoat layer between the aluminum substrate and a specific photosensitive layer, an extremely excellent target substrate can be obtained. The present invention has been reached.

That is, the gist of the present invention is that, in an electrophotographic photoreceptor having a photosensitive layer provided on an aluminum substrate, the aluminum substrate has an anodic oxide film, the photosensitive layer contains oxytitanium phthalocyanine, and An electrophotographic photoreceptor comprising an undercoat layer provided between an aluminum substrate and a photosensitive layer.

 Hereinafter, the present invention will be described in detail.

The electrophotographic photoreceptor of the present invention is characterized in that an anodic oxide film and an undercoat layer are provided on an aluminum substrate. As the aluminum used for the substrate, an aluminum alloy mainly composed of aluminum can be used as long as it is suitable for the use of the present invention.

The aluminum substrate is treated with an acid,
It is preferable to perform a degreasing treatment by various degreasing and washing methods such as an alkali, an organic solvent, a surfactant, an emulsion, and electrolysis.

The anodized film is usually formed by anodizing in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, boric acid, and sulfamic acid. give. In the case of anodic oxidation in sulfuric acid, the sulfuric acid concentration is 100 to 300 g /, the dissolved aluminum concentration is 2 to 15 g /, the liquid temperature is 15 to 30 ° C, and the electrolysis voltage is 5 to 20.
V and the current density are preferably set in the range of 0.5 to ² A / dm ² .

The average thickness of the anodic oxide film is usually 20 μm or less, and particularly preferably 7 μm or less.

In order to enhance the stability of the anodic oxide film formed in this manner, for example, a low-temperature sealing treatment in which the film is immersed in an aqueous solution containing nickel fluoride as a main component, or, for example, nickel acetate is used as a main component It is preferable to perform a high-temperature sealing treatment of dipping in an aqueous solution.

The concentration of the nickel fluoride aqueous solution used in the case of the low-temperature sealing treatment can be appropriately selected, but the most effective case is used in the range of 3 to 6 g /. Further, in order to smoothly proceed with 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 4.5.
It is good to process in the range of -6.5, preferably 5.5-6.0. Examples of the pH adjuster include oxalic acid, boric acid, formic acid, acetic acid, sodium hydroxide, aqueous ammonia and the like.

The processing time is preferably in the range of 1 to 3 minutes per 1 μm of the film thickness.

Note that additives such as cobalt fluoride, cobalt acetate, nickel sulfate, and a surfactant may be added to the nickel fluoride aqueous solution in order to further improve the film properties.

As the sealing agent in the case of the high-temperature sealing treatment, an aqueous solution of a metal salt such as nickel acetate, cobalt acetate, lead acetate, nickel-cobalt acetate, and barium sulfate can be used, and it is particularly preferable to use nickel acetate. .

The concentration when using an aqueous nickel acetate solution is 3 to 20 g /
It is preferable to use within the range. Processing temperature is 65-100
℃, preferably 80-98 ℃, pH of nickel acetate aqueous solution
Should be processed in the range of 5.0 to 6.0. Here, as the pH adjuster, for example, ammonia water, sodium acetate and the like can be used.

The processing time is 10 minutes or more, preferably 20 minutes or more. In this case, sodium acetate, an organic carboxylate, an anionic or nonionic surfactant may be added to the nickel acetate aqueous solution in order to improve the physical properties of the film.

 Next, it is washed with water and dried to complete the sealing process.

Next, an undercoat layer is provided on the anodic oxide film obtained as described above.

As the material for the undercoat layer, any suitable material such as the above-mentioned various materials can be used. For example, 6-aminocaproic acid, 11-aminoundecanoic acid, 12-
Aminocarboxylic acids such as aminolauric acid; or dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and 1,10-decanedicarnbonic acid, and diamines such as hexamethylenediamine, piperazine, and decamethylenediamine. It is preferable to use soluble nylon such as polymerized nylon or modified nylon.

The thickness of the undercoat layer is 5 μm or less, preferably 2 μm
It is preferably provided below.

As the photosensitive layer provided on the substrate on which the anodized film and the undercoat layer are formed as described above, various photosensitive layers using oxytitanium phthalocyanine can be used.
It is extremely useful to use a laminated photoconductor composed of a charge generation layer and a charge transfer layer.

Oxytitanium phthalocyanine is used in the charge generation layer of the stacked photoconductor.

The charge generation layer is usually formed as a uniform layer of oxytitanium phthalocyanine or in a state where oxytitanium phthalocyanine is dispersed as fine particles in a binder resin. Examples of the binder resin used here include phenoxy, epoxy, polyester, acrylic, polyvinyl acetal, and polycarbonate resin.

The thickness of the charge generation layer is usually 0.1 μm to 1 μm,
Preferably, the thickness is from 0.15 μm to 0.6 μm.

As the charge transfer material used for the charge transfer layer, a high molecular compound such as polyvinyl carbazole, polyvinyl pyrene, and polyacenaphthylene or a low molecular compound 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 polymethyl methacrylate, polystyrene, vinyl polymers such as polyvinyl chloride and copolymers thereof, polycarbonate, polyester, phenoxy, epoxy, silicone resins, and the like, and partially cross-linked cured products thereof. Can be used. The charge transfer layer may contain various additives such as an antioxidant and a sensitizer as needed.

The thickness of the charge transfer layer is usually 10 to 40 μm, preferably 10 to 40 μm.
Used with a thickness of 25 μm.

The electrophotographic photoreceptor of the present invention formed as described above,
It can be used for various electrophotographic processes including a reversal development system.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples as long as the gist is not exceeded.

Production of Photoconductor A A 1 mm thick aluminum cylinder having a mirror-finished surface was degreased and washed in a 30 g / water solution of a degreasing agent Top Alclean 160 (manufactured by Okuno Pharmaceutical Co., Ltd.) at 60 ° C. for 5 minutes. Subsequently, after washing with water, it was immersed in 7% nitric acid at 25 ° C. for 1 minute. Further, after rinsing with water, anodic oxidation was performed at a current density of 1.0 A / dm ^{2 in} a 180 g / sulfuric acid electrolytic solution (dissolved aluminum concentration: 7 g /) to form an anodic oxide film having an average film thickness of 6 μm. Then, after washing with water, 10 g of a high-temperature sealing agent Top Seal DX-500 (manufactured by Okuno Pharmaceutical Co., Ltd.) containing nickel acetate as a main component.
/ Water solution at 95 ° C for 18 minutes to perform sealing treatment. Subsequently, the substrate was sufficiently washed with pure water and dried.

Next, 6 / 6.6 / 12 copolymerized nylon (composition ratio is 30/36 / 34wt
%) In a mixed solvent of methanol: trichlene = 70: 30 with heating to prepare a 5% solution.

An aluminum cylinder drum provided with the previously prepared anodized film was dip-coated on this nylon solution, and an undercoat layer was provided so that the film thickness after drying was 0.3 μm.

Next, 10 parts by weight of oxytitanium phthalocyanine and 5 parts by weight of polyvinyl butyral resin (trade name: SREC BH-3, manufactured by Sekisui Chemical Co., Ltd.) were mixed with 1,2-dimethoxyethane 500
A weight part was added, and the mixture was pulverized and dispersed by a sand grind mill.

An aluminum cylinder coated with an undercoat layer was dip-coated on this dispersion, and a charge generation layer was provided so that the film thickness after drying was 0.4 μm.

 Next, this aluminum cylinder is
56 parts by weightThe following hydrazone compound 14 parts by weight,1.5 parts by weight of the following cyano compoundAnd polycarbonate resin (Mitsubishi Chemical Co., Ltd., Novare
Box 7030A) 100 parts by weight of 1,000 weight of 1,4-dioxane
Dip coating on the solution dissolved in the part, the film thickness after drying is 17 μm
The charge transfer layer was provided such that

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

Production of Photoreceptor B Photoreceptor B was prepared in the same manner as in the production of photoreceptor A, except that a 0.3 μm-thick sodium caseinate layer was provided instead of nylon as the undercoat layer in the production of photoreceptor A. .

Production of Photoconductor C A 1 mm thick aluminum drum having a mirror-finished surface was degreased and washed in a 50 g / water solution of a degreasing agent P ₃ T-580S (manufactured by Henkel Hakusui) at 60 ° C. for 5 minutes, followed by rinsing with water. After performing, in 170g / sulfuric acid (dissolved aluminum concentration 6g /
), Anodic oxidation was performed at a current density of 1.2 A / dm ² to form an anodic oxide film having an average film thickness of 6 μm. Then, after washing with water, 5 g of a sealing agent hard wall No. 5 (manufactured by Nichika Chemical Industry Co., Ltd.) / PH aqueous solution adjusted to pH 6.0 with acetic acid at 5 ° C. for 5 minutes at 33 ° C. It was immersed and sealed. Subsequently, it was sufficiently washed with pure water and dried.

On the aluminum drum provided with the anodic oxide film, a subbing layer, a charge generation layer, and a charge transfer layer similar to those of the photoconductor A were provided to prepare a photoconductor C.

Production of Photoreceptor D (Comparative Photoreceptor) Photoreceptor A was prepared in the same manner as photoreceptor A, except that no undercoat layer of copolymerized nylon was provided.

Production of Photoreceptor E (Comparative Photoreceptor) Photoreceptor E was prepared in the same manner as photoreceptor A except that no anodized film was provided.

Examples 1 to 3 and Comparative Examples 1 and 2 The photoconductors A to E were mounted on a commercially available reversal developing laser printer, and the image characteristics under each environmental condition were evaluated. The results are shown in Table 1. The photoconductors A, B, and C of the present invention were
Under any of the conditions, a good image without image defects was obtained, but in the photoreceptor of Comparative Example, uneven image defects presumed to be caused by black spots or foreign substances present on the anodic oxide film appeared, No satisfactory image was obtained.

As is clear from the above results, it is considered that the electrophotographic photoreceptor having the anodic oxide film and the undercoat layer of the present invention has excellent performance.

(Effect of the Invention) The electrophotographic photoreceptor obtained by the present invention shows stable electric characteristics under a wide range of environmental conditions including high humidity even when used in an electrophotographic system including a reversal development system process. , Fog and other image defects are extremely low,
Uniform and good images can be obtained. Therefore, it is very useful industrially.

Although the reason why such an effect is achieved is not necessarily clear, the anodizing treatment eliminates protrusions, deposits, dirt, and the like existing on the aluminum substrate, and the drying unevenness generated in the anodizing step. For
The reason is considered to be that the surface uniformity was excellent because of being covered with the undercoat layer.

Claims (1)

(57) [Claims] 1. An electrophotographic photosensitive member having a photosensitive layer provided on an aluminum substrate, wherein the aluminum substrate has an anodized film, the photosensitive layer contains oxytitanium phthalocyanine, and the aluminum substrate has An electrophotographic photosensitive member comprising an undercoat layer provided between a photosensitive layer and a photosensitive layer.