JPH08262775A - Photoreceptor substrate and photoreceptor drum - Google Patents

Abstract

PURPOSE: To provide a photoreceptor drum hardly causing fogging phenomenon and giving an image having high image quality and to provide a photoreceptor substrate giving the high performance photoreceptor drum by reducing the Ca, Na and K contents of the surface of an aluminum oxide layer. CONSTITUTION: When an aluminum oxide layer is formed on an electrically conductive substrate to obtain a photoreceptor substrate and an electric charge generating layer and an electric charge transferring layer are successively formed on the photoreceptor substrate to obtain a photoreceptor drum, the concns. of Ca, Na and K in the surface of the aluminum oxide layer are reduced to <=0.1wt.% each of the amt. of Al.

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, a copying machine, etc., and a photosensitive support which is a constituent material of the drum.
The present invention relates to a photosensitive drum capable of reproducing a high-quality image without causing a "fog phenomenon" (a phenomenon in which a print screen is black and lightly stained), and a photosensitive support which is a constituent material thereof.

[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 A photosensitive support is a conductive substrate A on which an aluminum oxide layer 1 for electrical insulation is formed as shown in FIG. 2, and is a constituent material of the photosensitive drum shown in FIG. Thus, a photoconductor drum is obtained by forming the charge generation layer 2 and the charge transfer layer 3 on the aluminum oxide layer 1 in the finishing process.

The charge generating layer 2 of the photosensitive layer B when used as a photosensitive drum plays a role of absorbing light to generate free charges, and its thickness is the range of the generated photo carriers. 0.1 to 2 μm for shortening
Is formed thin. 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 10 to 30 μm.
It is a degree.

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, the "fog phenomenon" occurs on the printing screen as described above. It is often experienced that it occurs and significantly reduces the sharpness of the image.

[0005]

The present invention has been made in view of these problems, and its purpose is to reproduce a high quality image without causing a "fog phenomenon". It is an object of the present invention to provide a photosensitive drum that can be used, and also to provide a photosensitive support that provides such a photosensitive drum.

[0006]

The constitution of the photosensitive support according to the present invention, which has been capable of solving the above-mentioned problems, is a photosensitive support formed by forming an aluminum oxide layer on a conductive substrate. The calcium concentration on the surface is 0.1% by weight or less with respect to aluminum, the sodium concentration is 0.1% by weight or less with respect to aluminum, and the potassium concentration is 0.1% by weight or less with respect to aluminum. However, it has a gist. Further, the constitution of the photosensitive drum according to the present invention has a gist in that a charge generation layer and a charge transfer layer are sequentially formed on a photosensitive support satisfying the above constitutional requirements.
The performance of the aluminum oxide layer in both of the above inventions can be further improved by suppressing the total amount of alkali metal and alkaline earth metal on the surface thereof to 0.3% by weight or less with respect to aluminum. Therefore, it is preferable.

[0007]

The present inventors aim to improve the "fog phenomenon" as described above, and in order to clarify the cause of the occurrence of the fog phenomenon. I conducted a survey from. As a result, it was found that the "fogging phenomenon" is more likely to occur as the concentration of the alkali metal such as sodium and potassium and the alkaline earth metal such as calcium on the surface of the aluminum oxide layer formed as the insulating layer is higher. Then, it was found that the "fogging phenomenon" can be remarkably improved by properly controlling the cleaning conditions and the like when the aluminum oxide layer is formed to reduce the specific impurity concentration on the surface as much as possible.

As a result of further pursuit based on these findings, when a large number of metals, such as alkali metals and alkaline earth metals, which are easily charged with electrostatic charges are present on the conductive substrate, The charges are easily injected, and as a result, the negative charges formed on the surface of the photosensitive drum during image formation are canceled and the initial potential decreases, which in turn lowers the charge level and decreases the printing sensitivity. In addition, when the above metal is present on the surface of the aluminum oxide layer, the positive charge generated by the light irradiation is trapped by the metal and a residual of the negative charge is generated. It was confirmed that the printing sensitivity became sufficient and the "fog phenomenon" was likely to occur.

Such a phenomenon occurs in 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 an alumite layer which is positively formed by anodic oxidation or the like, and an aluminum substrate in the atmosphere. The aluminum oxide layer formed by subjecting the surface to natural oxidation is generically referred to, but in the following description, the alumite layer will be described as a typical example), for example, a cation such as an alkali metal or an alkaline earth metal is added. It naturally occurs even when there is a substance that is likely to be generated.

Above all, sodium, potassium and calcium have a high ionization tendency and are mixed in the aluminum base metal and cannot be completely removed by melting and refining. Therefore, a small amount of mixing is unavoidable in aluminum.
Moreover, since a large amount of industrial water or the like is used in the alumite treatment step for forming the alumite layer, the above metals contained in the industrial water or the like may be taken into the alumite layer.

Therefore, in the present invention, N on the surface of the alumite layer is
Focusing on the respective concentrations of a, K, and Ca, the relationship with the amount of occurrence of the "fog phenomenon" was investigated. However, the experimental conditions and the like were as shown in Examples below.

The results are shown in FIG. 3, and the concentrations of Na, K and Ca on the surface of the alumite layer (content ratio with respect to Al)
The "fogging phenomenon" becomes more significant as the value becomes higher. In normal electrophotographic images, the "fog density" is 0.01
Up to 5 is acceptable as a product, but those exceeding 0.015 are rejected by the standard and those below 0.005 are considered excellent.

When the permissible limits of the respective contents of Ca, Na and K are obtained according to the above criteria, the Ca concentration is Ca / Al of 0.1% by weight or less (preferably 0.03% by weight or less),
Na concentration is 0.1% by weight or less (preferably 0.02% by weight or less) in Na / Al, and K concentration is 0.1% by weight or less (preferably 0.01% by weight or less) in K / Al. I understand that Note that these concentrations can be obtained by EPMA, X-ray photoelectron spectroscopy, or the like.

As described above, in the present invention, among the elements contained on the surface of the alumite layer which cause the "fog phenomenon", attention is paid particularly to Ca, Na and K, and the upper limits of the content rates thereof are defined. The feature is that the "fogging phenomenon" is reduced, and means for reducing these Ca, Na, and K are not particularly limited. But the general one is
Use pure water (distilled water or deionized water) in the water washing process after forming the alumite layer, or use a commercially available detergent (for example, neutral degreasing agent, weak alkaline degreasing agent, phosphoric acid degreasing agent, etc.) However, it is more preferable to use a scrubber to sufficiently clean the cleaning water while purifying the cleaning water. When a scrubber is used, well water can be used as washing water.

In the above description, the effect of Ca, Na, and K has been clarified, and the effect thereof has been clarified. However, in order to suppress the above "fog phenomenon" more effectively, the alkali metal and the alkaline earth metal are included. The total amount of 0.3 to aluminum
It has also been confirmed that it is desirable to limit the content to less than or equal to wt%, more preferably less than or equal to 0.05% by weight.

The formation of the alumite layer or the formation of the photosensitive layer after washing the alumite layer with water may be carried out by a conventional method, and a general 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 and 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, washing is sufficiently performed under the above-mentioned conditions to sufficiently remove Ca, Na and K on the surface of the alumite layer. When this process is completed, the photosensitive support of the present invention, which is a material for forming the photosensitive drum, is obtained.

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.), solvent (tetrahydrofuran, methylene chloride, etc.), etc. 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-) are applied to the surface of the charge generation layer. 1, 1-
Apply a charge transfer layer coating solution consisting of a hydrazone derivative such as diphenylhydrazone, a pyrazoline derivative, a polyvinylcarbazole derivative, a triphenylmethane derivative, an oxadiazole derivative) and a solvent (dichloromethane, dichloroethane, dichlorobenzene, etc.). When the photosensitive layer is formed by drying, the photosensitive drum of the present invention is obtained.

Regarding the photosensitive layer, the dispersion type coating as described above is the most general, but other than this, a vapor deposition type coating may be used, and a laminated type photoconductor in which the charge generation layer and the charge transfer layer are separated. In addition to the drum, it is also possible to use a single layer type in which the photosensitive layer is composed of one layer.

The photosensitive support or photosensitive drum thus obtained is particularly composed of Ca, N on the surface of the conductive substrate or on the surface of the alumite layer provided between the conductive substrate and the photosensitive layer.
Since the amounts of a and K are sufficiently reduced, charged charges and charges generated by laser irradiation are not trapped or the transfer of charges is not hindered, and there is no defect such as black spots. It gives a high quality image.

[0021]

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 pipe made of an aluminum alloy (A3003) degreased with an alkaline degreasing agent (outer diameter 30 mm × 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 ² A / dm ² , an alumite layer having a thickness of about 12 μm was formed.
After that, a sealing treatment was performed by immersing in a nickel acetate-based sealing liquid for 15 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 (using EPMA for measurement). In addition, washing with tap water was performed between the above-described alumite layer forming steps.

On the other hand, as a binder resin, polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., trade name "ESREC BL1") 10
0 parts by weight, 200 parts by weight of metal-free phthalocyanine (manufactured by Dainippon Ink) as a charge generating substance, and a predetermined amount of tetrahydrofuran were mixed and dispersed in a centrifugal ball mill for 1 hour to prepare a coating liquid for a charge generating layer. The coating liquid is applied to each of the drums obtained above by a dipping method, and the temperature is 110 ° C.
By heat-drying for 30 minutes and curing, a charge generation layer having a film thickness of 0.5 μm was formed.

Next, as a binder resin, a polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Inc., trade name "UPILON") 100
Parts by weight, 4-dibenzylamino-2 as a charge transfer material
-Methylbenzaldihydro-1,1-diphenylhydrazone (100 parts by weight) and a predetermined amount of dichloromethane were mixed by stirring with a homomixer to prepare a coating liquid for a charge transfer layer. This coating liquid is applied to the surface of the charge generation layer by a dipping method, and heat-dried at 90 ° C. for 30 minutes,
A charge transfer layer having a film thickness of 20 μm was formed to prepare a photoconductor drum 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 the extent of the “fog phenomenon” was examined. The "fogging phenomenon" was evaluated using a commercially available fogging densitometer (Macbeth densitometer manufactured by Sakata Inx Co., Ltd.).

The results are also shown in Table 1. In the examples in which the contents of Ca, Na, and K on the surface of the aluminum oxide layer were suppressed to the specified amounts or less, the "fog phenomenon" was observed as compared with the comparative example. It can be seen that there is very little, and it has excellent image sharpness.

[0028]

[Table 1]

[0029]

The present invention is constructed as described above, and by reducing the content of Ca, Na, and K on the surface of the aluminum oxide layer, the "fog phenomenon" is very small and a high quality image is provided. It has become possible to provide a photosensitive drum, as well as a photosensitive support that provides a high performance photosensitive drum.

[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 cross-sectional explanatory view illustrating a laminated structure of a photosensitive support according to the present invention.

FIG. 3 is a graph showing the relationship between the concentrations of Ca, Na, and K on the surface of the aluminum oxide layer and the degree of the “fog phenomenon”.

Claims (4)

[Claims] 1. A photosensitive support having an aluminum oxide layer formed on a conductive substrate, wherein the calcium concentration on the surface of the aluminum oxide layer is 0.1 to aluminum.
A photosensitive support characterized in that a sodium concentration is controlled to be not more than 0.1% by weight, a sodium concentration is not more than 0.1% by weight relative to aluminum, and a potassium concentration is not more than 0.1% by weight to aluminum. 2. The total amount of alkali metals and alkaline earth metals on the surface of the aluminum oxide layer is suppressed to 0.3% by weight or less with respect to aluminum.
The photosensitive support described in 1. 3. 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 calcium concentration on the surface of the aluminum oxide layer is 0.1 wt% or less with respect to aluminum, and the sodium concentration is 0.1 wt% with respect to aluminum. Below, the potassium concentration is 0.1% by weight with respect to aluminum.
A photosensitive drum characterized by being suppressed below. 4. The total amount of alkali metal and alkaline earth metal on the surface of the aluminum oxide layer is suppressed to 0.3% by weight or less with respect to aluminum.
The photosensitive drum according to 1.