JPH0772642A - Photosensitive drum - Google Patents

Abstract

PURPOSE:To provide the photosensitive drum which forms images having high image quality without having printing defects, such as black spots, by decreasing the contents of Ni, S and C1 in the surface of an aluminum oxide layer. CONSTITUTION:This photosensitive drum is constituted by forming a photosensitive layer consisting of a charge generating layer and charge transfer layer via an aluminum oxide layer on a conductive substrate. The content of the nickel in the surface of the aluminum oxide layer of such photosensitive drum is confined to <=6wt.%, more preferably <=4wt.% of the aluminum, the concn. of the sulfur therein to <=20wt.%, more preferably <=15wt.% of the aluminum and the concn. of the chlorine to <=0.2wt.%, more preferably <=0.1wt.% of the aluminum, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive drum used for an electrophotographic printer or a copying machine,
In particular, the present invention relates to a photoconductor drum capable of reproducing a high-quality image without causing printing defects such as black spots.

[0002]

2. Description of the Related Art As shown in FIG. 1, a photosensitive drum used for the above-mentioned applications has an aluminum oxide layer 1 such as alumite for electrical insulation on a conductive substrate A made of an aluminum alloy. It has a laminated structure in which a photosensitive layer B composed of a charge generation layer 2 and a charge transfer layer 3 is formed via

The charge generating layer 2 of the photosensitive layer B plays a role of absorbing light to generate free charges, and its thickness is 0.1 to shorten the range of generated photo carriers. It is formed to a thin thickness of 2 μm. This is because most of the incident light is absorbed by the charge generation layer 2 and many photo carriers are generated, and the generated photo carriers are injected into the charge transfer layer 3 without being deactivated by recombination or capture. This is because. On the other hand, the charge transfer layer 3 has a role of accepting electrostatic charges and a function of transporting free charges, and its thickness is usually about 10 to 30 μm.

However, when such a conventional photosensitive drum having a laminated structure is used and a laser printer or the like line scans a laser beam to reveal an image, printing defects such as black spots and white spots appear. There is.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of these problems, and an object thereof is to reproduce a high quality image without causing printing defects such as black dots. The present invention is intended to provide a photoconductor drum that can be used.

[0006]

A photosensitive drum according to the present invention which can solve the above-mentioned problems comprises an aluminum oxide layer, a charge generation layer and a charge transfer layer which are sequentially formed on a conductive substrate. In the photoconductor drum, the nickel concentration on the surface of the aluminum oxide layer is 6 wt% or less with respect to aluminum, more preferably 4 wt% or less, and the sulfur concentration is 20 wt% or less with respect to aluminum, more preferably 15 wt% or less. The gist is that the chlorine concentration is suppressed to 0.2% by weight or less, more preferably 0.1% by weight or less with respect to aluminum.

[0007]

The present inventors have investigated the causes of the generation of black spots and white spots under the above-mentioned problems to be solved, and the following can be considered. First, when a metal having a high work function is present on the conductive substrate, the metal may trap the charge generated by charging or the charge generated by laser light irradiation, or may interfere with the movement of the charge. When the charge generated by charging is trapped, black spots are generated due to the decrease in electrification voltage, and when the charge generated by laser light irradiation is trapped or movement of the charge is obstructed, the irradiation potential does not decrease and white It causes points.

Such a phenomenon is caused by the fact that the basic surface in the atmosphere is the vicinity of the charge generation layer (that is, the surface of the aluminum oxide layer) (in the present invention, the aluminum oxide layer is not only the alumite layer which is positively formed by anodic oxidation etc. The aluminum oxide layer formed by subjecting to natural oxidation is generically referred to, but in the following description, the alumite layer will be representatively described) and naturally occurs even when a substance easily ionized exists.

For example, FIGS. 3 (A) and 3 (B) show EPMA qualitative analysis charts (PBS in the figure) of a black spot generating portion and a normal portion.
T is lead stearate, RAP is acid rubidium phthalate, PET is pentaerythritol, and LIF is lithium fluoride), and the amount of Ni, S, and Cl is large in the black spot generation portion. Sulfuric acid is used as S for the anodizing electrolyte of Al for forming an alumite layer by anodic oxidation, so S mixed as sulfuric acid ions in the anodized film is detected, and
Is considered to be mixed in in the Ni salt sealing treatment step performed to improve the corrosion resistance and the stain resistance after anodization. Further, it is considered that Cl is mixed with Cl in the wash water used for washing after each treatment step.

Generally, N is an element having a large work function.
In addition to i, there are Au, Pt, Pd, and the like, and examples of substances that are easily ionized include phosphoric acid, oxalic acid, boric acid, sodium hydroxide, and other anodizing electrolyte solutions, as well as many substances such as acetic acid, hydrochloric acid, and nitric acid. As is clear from FIG. 3, in the alumite layer forming method which is generally adopted when manufacturing the photoconductor drum having the above-mentioned laminated structure, the work function of the work function mixed in the alumite layer surface is Special attention must be paid to Ni, S, and Cl as large elements.

Therefore, in the present invention, N on the surface of the alumite layer is
Focusing on the respective concentrations of i, S, and Cl, the relationship with the print defect (black dot) generation amount was investigated. However, the experimental conditions and the like were as shown in Examples below.

The results are shown in FIG. 2, and the concentrations of Ni, S and Cl on the surface of the alumite layer (content ratio to Al)
The number of sunspots increases sharply with increasing. In normal electrophotographic images, up to 3 sheets of A4 size paper (6 dm ² ) are acceptable as products, but if more than 3 sheets are rejected by the standard, 0.5 sheets / dm ² or less Things are considered excellent.

When the permissible limits of the respective contents of Ni, S, and Cl are obtained in accordance with these criteria, the Ni concentration is Ni / Al of 6 wt% or less (preferably 4 wt% or less), and the S concentration is S.
/ Al is 20 wt% or less (preferably 15 wt% or less), Cl concentration is 0.2 wt% or less (preferably 0.1
It can be seen that it may be suppressed to less than 1% by weight).

As described above, in the present invention, among the contained elements on the surface of the alumite layer which cause printing defects, attention is paid particularly to Ni, S and Cl, and the black spots are reduced by defining the upper limits of their contents. However, it is characterized, and means for reducing these Ni, S, and Cl is not particularly limited. However, in general, pure water (distilled water or deionized water) is used in the washing process after the alumite layer is formed,
Alternatively, a commercially available cleaning agent (for example, a neutral degreasing agent, a weak alkaline degreasing agent, a non-phosphoric acid degreasing agent, etc.) is used, and more preferably a method of thoroughly cleaning while cleaning the cleaning water using a scrubber. is there. When using a scrubber, it is also possible to use well water as washing water. However, tap water contains a large amount of chlorine used for sterilization,
It is not preferable because it becomes a source of Cl contamination.

The formation of the alumite layer and the formation of the photosensitive layer after washing with water of the alumite layer may be carried out by a conventional method, but a typical method is as follows. In some cases, the positive formation of the alumite layer by anodic oxidation may be omitted, and the photosensitive layer may be directly formed on the aluminum oxide layer formed on the surface of the substrate by oxidation in the atmosphere.

First, degreasing cleaning of a drum-shaped substrate made of an aluminum alloy → removal of an oxide film by immersion in an alkaline aqueous solution → neutralization by immersion in an aqueous nitric acid solution → formation of an alumite layer by anodic oxidation in an aqueous sulfuric acid solution. After carrying out, Ni, S, and Cl on the surface of the alumite layer are sufficiently removed by sufficiently washing under the above-mentioned conditions.

Next, the alumite layer forming drum is treated with a binder resin (polyvinyl butyral, etc.), a charge generating substance (phthalocyanine pigment such as metal-free phthalocyanine, azo pigment, perylene pigment etc.) and solvent (tetrahydrofuran, methylene chloride etc.) and the like. Is applied by an impregnation method or the like, and a binder resin (polycarbonate or the like) and a charge transfer substance (4-benzylamino-2-methylbenzaldihydro-1) are applied to the surface of the charge generation layer. , 1-diphenylhydrazone, and other hydrazone derivatives, pyrazoline derivatives, polyvinylcarbazole derivatives, triphenylmethane derivatives, oxadiazole derivatives, etc.) and solvents (dichloromethane, dichloroethane, dichlorobenzene, etc.), etc. Apply liquid and dry to form photosensitive layer The method and the like.

In the photoconductor drum thus obtained, the amount of Ni, S, and Cl on the surface of the alumite layer provided between the conductive substrate and the photoconductor layer is sufficiently reduced. The generated charges are not trapped or the transfer of the charges is not hindered, and a high quality image without defects such as black spots is provided.

[0019]

EXAMPLES Next, examples of the present invention will be shown, but the present invention is not limited by the following examples, and may be carried out with appropriate modifications within a range compatible with the gist of the preceding and following description. Of course, it is possible, and all of them are included in the technical scope of the present invention.

Example Extruded tube made of an aluminum alloy (A3003) degreased with an alkaline degreasing agent (outer diameter 30 mm x inner diameter 28 mm)
(Length 300 mm) is immersed in 80 g / liter sodium hydroxide aqueous solution (30 ° C.) for 2 minutes to remove the surface oxide film, and then immersed in 10 wt% nitric acid aqueous solution to neutralize the substrate surface. To do. Then, by anodizing in a 10 wt% sulfuric acid aqueous solution at a current density of 3 A / dm ² , an alumite layer having a thickness of about 15 μm was formed.
After that, the sealing treatment was performed by immersing in a nickel acetate-based sealing liquid for 20 minutes.

The obtained treated material was washed by changing the washing method as shown in Table 1 to control the impurity concentration on the surface of the alumite layer. In addition, washing with tap water was performed between the above-described alumite layer forming steps.

On the other hand, 100 parts by weight of polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., trade name Eslec BL1) as a binder resin, 200 parts by weight of metal-free phthalocyanine (manufactured by Dainippon Ink) as a charge generating substance, and a predetermined amount of tetrahydrofuran were used. A centrifugal ball mill was used to mix and disperse the coating solution for 1 hour to prepare a coating solution for the charge generation layer, and the coating solution was applied to each of the drums obtained above by a dipping method, and the coating solution was heated at 110 ° C. for 3 hours.
A film thickness of 0.5 is obtained by heating and drying for 0 minutes and curing.
A charge generation layer of μm was formed.

Next, 100 parts by weight of a polycarbonate resin (trade name: Iupilon manufactured by Mitsubishi Gas Chemical Co., Inc.) as a binder resin, and 4-dibenzylamino-2-methylbenzaldihydro-1,1-diphenylhydrazone as a charge transfer material. 100 parts by weight and a predetermined amount of dichloromethane were stirred and mixed with a homomixer to prepare a charge transfer layer coating liquid. The coating liquid was applied to the surface of the charge generation layer by a dipping method and heat-dried at 90 ° C. for 30 minutes to give a film thickness of 20.
A μm charge transfer layer was formed to prepare a photoconductor for a laser printer.

A semiconductor laser (λ = 780 nm, exposure intensity = 0.7 mw / cm ² ,
It was applied to a laser printer using an exposure time of 260 μsec), and printability evaluation and electrostatic voltage measurement by a micro electrostatic voltmeter were performed.

The results are also shown in Table 1. In the examples in which the respective contents of Ni, S and Cl on the surface of the alumite layer were suppressed to the specified amounts or less, the number of black spots was much higher than that in the comparative example. It can be seen that it has a very small and excellent charging voltage.

[0026]

[Table 1]

[0027]

The present invention is constructed as described above, and by reducing the content of Ni, S, and Cl on the surface of the alumite layer, a photoreceptor which gives a high-quality image without printing defects such as black spots. Drums could be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view illustrating a laminated structure of a photosensitive drum according to the present invention.

FIG. 2 is a graph showing the relationship between the respective concentrations of Ni, S, and Cl on the surface of the alumite layer and the number of black dots generated in a printed image.

FIG. 3 shows the alumite layer E for the black spot generation area and the normal area.
It is a figure which compares and shows a DS analysis chart.

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[Procedure amendment]

[Submission date] June 30, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

As described above, in the present invention, among the contained elements on the surface of the alumite layer which cause printing defects, attention is paid particularly to Ni, S and Cl, and the black spots are reduced by defining the upper limits of their contents. However, it is characterized, and means for reducing these Ni, S, and Cl is not particularly limited. However, in general, pure water (distilled water or deionized water) is used in the washing process after the alumite layer is formed,
Alternatively, a commercially available cleaning agent (for example, a neutral degreasing agent, a weak alkaline degreasing agent, a non-phosphoric acid degreasing agent, etc.) is used, and more preferably a method of thoroughly cleaning while cleaning the cleaning water using a scrubber. is there. When a scrubber is used, well water can be used as washing water. However, tap water contains a large amount of chlorine used for sterilization,
It is not preferable because it becomes a source of Cl contamination.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Fig. 3] Anodized layer for black spot generation area and normal area
It is a figure which compares and shows the EPMA qualitative analysis chart of.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (2)

[Claims] 1. An aluminum oxide layer on a conductive substrate,
In a photoreceptor drum having a charge generation layer and a charge transfer layer sequentially formed, the nickel concentration on the surface of the aluminum oxide layer is 6 wt% or less with respect to aluminum, the sulfur concentration is 20 wt% or less with respect to aluminum, and the chlorine concentration is And 0.2% by weight relative to aluminum, respectively. 2. The nickel concentration on the surface of the aluminum oxide layer is suppressed to 4% by weight or less with respect to aluminum, the sulfur concentration is 15% by weight or less with respect to aluminum, and the chlorine concentration is suppressed to 0.1% by weight or less with respect to aluminum. The photosensitive drum according to claim 1, which is a drum.