JPH06202363A - Electric conductive substrate for electrophotographic sensitive body and sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body capable of giving a very satisfactory image without a moire unevenness of image gradation at all even when the sensitive body is used in an electro-photographic process using coherent light as a light source in a laser beam printer, etc., and also giving a satisfactory image free from fog, black spots and white spots. CONSTITUTION:An Al or Al-alloy substrate is anodically oxidized after etching with an etchant contg. hydroxide of an alkali metal and weak acid salts of an alkali metal and/or an alkaline earth metal to obtain the objective electric conductive substrate for an electrophotographic sensitive body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive substrate for an electrophotographic photoreceptor and a photoreceptor. More specifically, the present invention relates to a conductive substrate and a photoconductor for an electrophotographic photoconductor, which are used in an apparatus in which an image is formed using an electrophotographic process in which coherent light is used as a light source, such as a laser printer.

[0002]

2. Description of the Related Art Electrophotographic technology has been widely used and applied not only in the field of copying machines but also in the field of various printers in recent years because of its ability to obtain images of instant quality and high quality. Regarding photoconductors, which are the core of electrophotographic technology, conventional photoconductive materials include selenium, arsenic-selenium alloys, cadmium sulfide, inorganic photoconductors such as zinc oxide and amorphous silicon, and recently organic compounds. Organic photoconductors composed of various combinations of the following charge generating agents and charge transporting agents have been developed and widely used.

[0003]

When these photoconductors are mounted on a copying machine or a printer that uses LED light as a light source to form an image, a good image can be obtained and there is no particular problem. When used in an electrophotographic process in which coherent light from a laser or the like is used as a light source, moire-like shading occurs in an image, and a good image is often not formed, which is a serious problem.

The following can be considered as the cause of this. That is, since the applied light is coherent light, interference occurs between the light reflected on the surface of the photoconductor and the light reflected from the inside of the photoconductor. Here, the light reflected from the inside of the photoconductor is the light reflected from the substrate, and the light reflected from the interface of each layer in the case of a laminated type photoconductor composed of an organic charge generation layer and a charge transport layer or an amorphous silicon photoconductor composed of multiple layers. Can be considered. As a result, it is considered that the intensity of light is caused by such interference, and as a result, the light irradiation to the photoconductor and the developing potential become non-uniform, and a moire-like uneven density appears on the image. In particular, when a halftone image is taken, this phenomenon becomes remarkable. Various methods have been proposed so far in order to improve such uneven density. For example, a method of treating a substrate made of aluminum with black alumite to reduce the reflectance of the substrate (JP-A-59).
Similarly, a method of performing satin treatment by mechanical cutting, a method of performing sandblasting, and a method of performing etching treatment on the surface of a substrate are similarly disclosed (JP-A-1-188860).
Etc. are known. However, these methods may not be sufficiently effective or may cause problems such as contamination of the surface of the substrate during the treatment process, and a more reliable and effective method is desired.

[0005]

Means for Solving the Problems As a result of intensive studies made by the present inventors in order to solve such problems, as a result, an electrophotographic photosensitive member using an electroconductive substrate which has been anodized after being etched with a specific etching agent is used. The present inventors have found that the body can form a good image with no uneven density even in an electrophotographic process using coherent light as a light source.

That is, the gist of the present invention consists of aluminum or an aluminum alloy which has been anodized after being etched by an etching agent containing a hydroxide of an alkali metal and a weak acid salt of an alkali metal and / or an alkaline earth metal. The present invention relates to a conductive substrate for an electrophotographic photosensitive member and an electrophotographic photosensitive member using the conductive substrate.

The present invention will be described in detail below. The electroconductive substrate for electrophotographic photoreceptor of the present invention is made of aluminum or aluminum alloy. The conductive substrate is subjected to anodizing treatment after etching with an etching agent. As a pretreatment for these treatments, degreasing treatment is performed with various degreasing cleaning methods such as acid, alkali, organic solvent, surfactant, emulsion, electrolysis, etc. Preferably.

The conductive substrate thus degreased is then subjected to an etching treatment with the etching agent according to the present invention. The etching agent used here contains a hydroxide of an alkali metal and a weak acid salt of an alkali metal and / or an alkaline earth metal as active ingredients. As the alkali metal hydroxide, sodium hydroxide and potassium hydroxide are preferable. The weak acid salt of alkali metal or alkaline earth metal may be a normal salt or a hydrogen salt, examples of the alkali metal include sodium and potassium, and examples of the alkaline earth metal include magnesium and calcium. . Examples of the weak acid used for the weak acid salt of alkali metal or alkaline earth metal include inorganic acids such as carbonic acid, phosphoric acid and silicic acid, and organic acids such as acetic acid, tartaric acid and succinic acid, and especially -log Ka (K
a: an acid having a dissociation constant as an acid) of 2 or more, and preferably an acid of 3 or more. The proportion of the alkali metal hydroxide and the weak salt of the alkali metal or alkaline earth metal in the etching agent can be appropriately changed, but is preferably 6 for each.
It is 0 to 90% by weight, 10 to 30% by weight, and more preferably 70 to 85% by weight and 10 to 25% by weight, respectively.
In addition, a surfactant and a chloride of an alkali metal may be contained as a liquid property improver for performing uniform etching. Although the concentration of the etching agent aqueous solution, the treatment temperature, and the treatment time can be selected as appropriate, for example, the concentration is 0.5% to 10%.
%, Especially 0.5% to 5%, and the treatment temperature is 40%.
C. to 80.degree. C., particularly 40.degree. C. to 60.degree. C., and the treatment time is preferably in the range of 1 minute to 15 minutes. Further, if the aluminum substrate is immersed in the aqueous solution of the etching agent as it is, it is rapidly etched. However, in order to avoid this, it is preferable to dissolve aluminum ions in the aqueous solution of the etching agent in advance and then perform the etching. The dissolved aluminum ion concentration in this case is 0.1 to 2%
It is preferable to adjust

When the etching agent of the present invention is used, it is easier to control the degree of etching and it is easier to obtain an appropriate rough surface, as compared with the case of using an alkali metal hydroxide alone. If the roughness of the conductive substrate surface after the etching treatment is too small, interference is likely to occur. On the other hand, if it is too large, the rough surface remains even after the subsequent treatment such as anodic oxidation treatment, and image defects such as fog are likely to occur. Therefore, the roughness R _max of the conductive substrate surface after the etching treatment (JIS B 0601-1970)
Is preferably about 2 to about 4 μm. The degree of etching of the surface of the conductive substrate after the treatment such as anodizing treatment described later and before the photoconductive layer is formed is determined by the roughness R.
_max (JIS B 0601-1970) is 0.2-
It is preferable to adjust to 1.5 μm, and it is more preferable that R _max is 0.5 to 1 μm.

The conductive substrate thus etched is subsequently subjected to treatments such as washing with water, neutralization with an acid and washing with water. Next, the conductive substrate obtained through the above treatment is anodized. The anodized film is usually formed by anodizing treatment in an acidic bath of chromic acid, sulfuric acid, oxalic acid, boric acid, sulfamic acid, etc. in which aluminum ions are dissolved. Is preferred. In the case of anodizing treatment in sulfuric acid, the sulfuric acid concentration is 100 to 300 g / 1, the dissolved aluminum ion concentration is 2 to 15 g / 1, the liquid temperature is 10 to 30 ° C., preferably 10 to 25 ° C., and the electrolysis voltage is 5 to 20 V. The current density is preferably set in the range of 0.5 to ² A / dm ² . The average film thickness of the anodized film is usually 20 μm or less, especially 10 μm.
It is preferably formed to be m or less.

The anodic oxide coating thus formed is
A low temperature sealing treatment or a high temperature sealing treatment is performed. Nickel fluoride is preferable as the sealing agent in the case of the low temperature sealing treatment, and the concentration of the nickel fluoride aqueous solution can be appropriately selected,
It is most effective when used within the range of 6 g / 1. Further, 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 It is better to process within the range. As the pH adjuster, oxalic acid, boric acid, formic acid, acetic acid, caustic soda, sodium acetate, aqueous ammonia, etc. can be used. The treatment time is preferably within the range of 1 to 3 minutes per 1 μm of the average film thickness of the coating. In order to further improve the physical properties of the coating, cobalt acetate, nickel sulfate, a surfactant, etc. may be added to the nickel fluoride aqueous solution.

As the sealing agent in the high temperature sealing treatment, an aqueous solution of a metal salt of nickel acetate, cobalt acetate, lead acetate, nickel acetate-cobalt, barium nitrate or the like can be used, but nickel acetate is particularly preferably used. Is preferred. When using an aqueous solution of nickel acetate, the concentration is 3 to 20 g /
It is preferably used within the range of 1. The processing temperature is usually
The temperature is 65 to 100 ° C., preferably 80 to 98 ° C., and the pH of the nickel acetate aqueous solution is 5 to 6, preferably 5.5 to 6. Ammonia water, sodium acetate, etc. can be used as the pH adjuster. The treatment time is preferably in the range of 2 to 10 minutes per 1 μm of the average film thickness of the coating. 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.

The electroconductive substrate that has been subjected to the anodizing treatment and the sealing treatment as described above is subsequently washed with water, dried naturally or with hot air, and then cooled to room temperature to provide a photoconductive layer. Further, if necessary, an intermediate layer having a barrier function and an adhesive function may be provided between the conductive substrate and the photoconductive layer. The photoconductive layer may be either an inorganic type or an organic type. As the inorganic photoconductive layer, for example, selenium, arsenic-selenium alloy, cadmium sulfide, zinc oxide or amorphous silicon can be used, and it is usually formed by a known method such as vapor deposition, sputtering or coating. As the organic photoconductive layer, for example, a laminated type photoreceptor having a charge generation layer and a charge transport layer laminated, a so-called dispersion type photoreceptor having a charge generation material dispersed in the charge transport layer, or the like can be used. Here, as the charge generation layer, a vapor-deposited film of an organic pigment such as phthalocyanine or an azo pigment, or a film obtained by dispersing them in a resin by a usual method such as dipping, spraying or spiral coating is used. Can be used. Further, as the charge transport layer, any of those in which a charge transport substance such as a hydrazone derivative or an aromatic amine derivative is dispersed in a binder resin, or a polymer charge transport agent such as polyvinylcarbazole can be used. It can be manufactured by the method of. Furthermore, an inorganic photoconductive layer may be used as the charge generation layer, and a composite photoconductive layer using an organic photoconductive layer as the charge transport layer may be used.

[0014]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

Example 1 An aluminum cylinder (material 6063) having an outer diameter of 30 mm, a length of 250 mm and a wall thickness of 1 mm having a mirror-finished surface was used as a degreasing agent (product name NG- #).
30 in a 30 g / 1 aqueous solution of Kizai Co., Ltd. 60
Degreasing cleaning was performed at 5 ° C for 5 minutes. Subsequently, after washing with water, an aqueous solution of an etching agent [P ₃ T651, which was heated to 50 ° C., was used.
(Henkel Hakusui Co., Ltd., composition: sodium hydroxide 76
%, Sodium carbonate 18%, sodium phosphate 3%, sodium chloride 3%) 1.2% aqueous solution containing 0.3% of aluminum (material 6063) dissolved therein for 4 minutes for etching treatment. Then immediately after washing with water 7
% Nitric acid at 25 ° C. for 1 minute. After washing with water, 180
in sulfuric acid electrolyte of g / 1 (dissolved aluminum ion concentration 7
g / 1) was anodized at a current density of 1.2 A / dm ² to form an anodized film having an average film thickness of 6 μm. Then, after washing with water, a high-temperature sealing agent containing nickel acetate as a main component (trade name Topseal DX-500, Okuno Chemical Industry Co., Ltd.)
(Manufactured by Mitsui Chemical Co., Ltd.) for 10 minutes at 95 ° C. for 30 minutes for sealing treatment. Subsequently, it was washed with water while applying ultrasonic waves and then dried.

Next, oxytitanium phthalocyanine 10
Parts by weight, polyvinyl butyral (Denki Kagaku Kogyo Co., Ltd.)
Manufactured by Denka Butyral 6000C) 1,2-
After adding 500 parts by weight of dimethoxyethane, the mixture was pulverized and dispersed by a sand grind mill. An aluminum cylinder provided with an anodized film formed previously 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, 56 parts by weight of N-methylcarbazole-3-carbaldehyde diphenylhydrazone and 14 parts by weight of 3,3-di (4-methoxyphenyl) acrolein diphenylhydrazone were added to the aluminum cylinder.
-(2,2-Dicyanovinyl) phenyl-2,4,5-
1.5 parts by weight of trichlorobenzene sulfonate and 100 parts by weight of a polycarbonate resin (Novalex (registered trademark) 7030A manufactured by Mitsubishi Kasei Co., Ltd.) are applied by dipping and coating in a solution prepared by dissolving 1000 parts by weight of 1,4-dioxane, and dried. A charge transfer layer was provided so that the subsequent film thickness would be 17 μm. The photoconductor thus obtained is referred to as photoconductor A.

(Example-2) A photoconductor B was prepared in the same manner as in Example-1, except that the etching temperature was changed to 56 ° C.

(Example-3) In Example-1, the concentration of aluminum dissolved in the aqueous solution of the etching agent was adjusted to 0.
Photoreceptor C was produced in the same manner as in Example 1 except that the content was 6%.

(Embodiment 4) In Embodiment 1, the etching temperature is 50 ° C. and the concentration of the aqueous etchant solution is 2.
A photoconductor D was prepared in the same manner as in Example 1 except that the content was 0%.

(Embodiment 5) In Embodiment 1, the etching temperature is 45 ° C. and the concentration of the aqueous etching agent solution is 3.
Photoreceptor E was prepared in the same manner as in Example 1 except that the concentration of aluminum dissolved in the aqueous solution of the etching agent was 0% and was 0.6%.

(Embodiment 6) In Embodiment 1, the etching temperature is 45 ° C. and the concentration of the etching agent aqueous solution is 3.
A photoconductor F was prepared in the same manner as in Example-1 except that the concentration of 0% and the aluminum dissolved in the aqueous solution of the etching agent was set to 0.9%.

Example-7 In Example-1, the etching temperature was 45 ° C., and the concentration of the aqueous etchant solution was 4.
A photoreceptor G was prepared in the same manner as in Example-1 except that the concentration of aluminum dissolved in the aqueous solution of the etching agent was 0% and was 0.6%.

Example-8 In Example-1, the etching temperature was 45 ° C., and the concentration of the aqueous etchant solution was 4.
A photoconductor H was prepared in the same manner as in Example-1 except that the concentration of aluminum dissolved in the aqueous solution of the etching agent was 0% and 0.9%.

(Comparative Example-1) The same photosensitive layer as in Example-1 was provided directly on an aluminum cylinder (material 6063) having an outer diameter of 30 mm, a length of 250 mm and a wall thickness of 1 mm, the surface of which was mirror-finished. Was produced.

(Comparative Example-2) A comparative photoconductor J was prepared in the same manner as in Example-1, except that the etching treatment was not carried out.

(Comparative Example-3) A comparative photoconductor K was prepared in the same manner as in Example-1, except that a 3% aqueous solution of sodium hydroxide was used as the aqueous etching solution.

(Example-9) A photoconductor L was prepared in the same manner as in Example-1 except that an etching agent containing 85% sodium hydroxide and 15% sodium acetate was used.

Example 10 A photoconductor M was prepared in the same manner as in Example 1 except that the etching agent containing 85% sodium hydroxide and 15% sodium hydrogen carbonate was used.

(Example-11) In Example-1, sodium hydroxide 85%, sodium dihydrogen phosphate 15%
A photoconductor N was prepared in the same manner as in Example 1 except that the etching agent of was used.

Comparative Example-4 A comparative photoconductor O was prepared in the same manner as in Example-1, except that a 1.02% aqueous solution of sodium hydroxide was used as the aqueous etching solution.

Roughness R _max (JIS B of the surface of the conductive substrate after the etching treatment in Examples 1, 9 and 10)
0601-1970) was 3.6, 2.2 and 3.8 μm, respectively. Roughness R _max (JIS B 06) of the surface of the conductive substrate after anodizing treatment in Example-1
01-1970) was 0.8 μm. The roughness R _max (JIS B0601-1970) of the conductive substrate surface after the etching treatment in Comparative Examples 3 and 4 was 5.0 and 4.6, respectively.

Next, a commercially available reversal development type laser printer (manufactured by NEC Corporation, PC-PR) was used as the photoreceptor.
1000) and evaluated the image characteristics under each environment. As a result, the photoconductors A to H and L to N of the examples
In each case, 5 ° C / 10%, 25 ° C / 60%, 35 ° C /
Under all environmental conditions of 85%, no moire-like shading was observed at all, and good images were obtained on both white and black backgrounds. On the other hand, in the photoconductor I of Comparative Example-1, in the halftone image, moire-like light and shade unevenness occurred on the entire surface. The photoconductor J of Comparative Example-2 produced lighter shades than the photoconductor I, but similar unevenness in density occurred. Comparative example-
With the photoconductors K and O of Nos. 3 and 4, no moire-like light and shade unevenness was generated, but a fog phenomenon in which black dots appeared on the entire white background image occurred, and a good image was not obtained. It is considered that this fog has a point where injection of charges from the conductive substrate side occurs at the time of charging the photoconductor because the surface is too rough due to etching, and this point becomes a black point on the image. From the above results, it can be judged that the electrophotographic photosensitive member according to the production method of the present invention has extremely excellent performance.

[0034]

When the etching agent according to the present invention is used, a conductive substrate having an appropriate rough surface can be easily obtained. Therefore, the electrophotographic photosensitive member using the conductive substrate which has been subjected to the specific treatment according to the present invention becomes a problem with a normal photosensitive member even when used in an electrophotographic process using coherent light as a light source such as a laser printer. It is possible to obtain a very good image without generating moire-like image unevenness at all. Also small defects on the surface of the substrate, excessive etching,
Image defects caused by stains and the like are almost completely removed by the processing of the present invention, so that a good image without fog, black spots, and white spots can be obtained.

Claims (2)

[Claims] 1. An electrophotographic photosensitive member made of aluminum or an aluminum alloy which has been anodized after etching treatment with an etching agent containing a hydroxide of an alkali metal and a weak acid salt of an alkali metal and / or an alkaline earth metal. Conductive substrate. 2. An electrophotographic photosensitive member comprising a conductive substrate for electrophotographic photosensitive member according to claim 1 provided with at least a photoconductive layer.