JPH04241358A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body perfectly preventing the occurrence of an interference fringe pattern when an image is formed and the occurrence of white spots when an image is formed at the beginning of use and at the time of repeated use or the occurrence of black spots in a reversal developing system. CONSTITUTION:When a photoconductive recording layer is formed on an electrically conductive substrate to obtain an electrophotographic sensitive body, the surface of the substrate is roughened so as to regulate the average roughness Ra along the center line to >=0.13mum and the max. width of the recessed part to <=10mum.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor in which a photosensitive layer is formed on a conductive substrate subjected to surface roughening treatment.
More specifically, the present invention relates to an electrophotographic photoreceptor suitable for an electrophotographic printer that uses a laser beam to perform imagewise line scanning.

0002

[Prior Art] Conventionally, electrophotographic printers that use line scanning with a laser beam have
Relatively short-wavelength gas lasers such as helium-cadmium lasers, argon lasers, and helium-neon lasers are used, and the electrophotographic photoreceptor used therefor has a CdS-binder-based photosensitive layer that forms a thick photosensitive layer. , Charge Transfer Complexes (IBM Journal
of the Research and D
development, January 1971, p57-p8
9) was used, the laser beam did not undergo multiple reflections within the photosensitive layer, and in fact, no interference fringe pattern appeared during image formation. However,
Semiconductor lasers have recently come to be used in place of the gas lasers mentioned above in order to design devices that are smaller and lower in cost. This semiconductor laser generally has an oscillation wavelength in a long wavelength region of 750 nm or more, and therefore an electrophotographic photoreceptor with high sensitivity characteristics in the long wavelength region is required. has been developed.

[0003] So far known long wavelength light (for example,
Examples of the photoreceptor having photosensitivity to wavelengths (600 nm or higher) include photosensitive layers containing phthalocyanine pigments such as copper phthalocyanine and aluminum chloride phthalocyanine;
In particular, a laminated electrophotographic photoreceptor having a photosensitive layer having a laminated structure of a charge generation layer and a charge transport layer, or an electrophotographic photoreceptor using a selenium-tellurium film is known. When a photoreceptor that is sensitive to such long wavelength light is attached to a laser beam scanning type electrophotographic printer and exposed to laser beams, an interference fringe pattern appears in the formed toner image, resulting in a good image. This method has the disadvantage that a reproduced image cannot be formed. One of the reasons for this is, for example, that the long wavelength laser is not completely absorbed within the photosensitive layer, and the transmitted light is specularly reflected at the substrate surface or the laminated interface of the photosensitive layer, and as a result, the laser beam is not absorbed within the photosensitive layer. The cause is said to be that multiple reflected light is generated, which causes interference with the reflected light from the surface of the photosensitive layer.

[0004] As a method to overcome this drawback, there have been methods disclosed in Japanese Patent Application Laid-open Nos. 58-162975 and 59-74567.
No. 60-79360, No. 60-112049,
As described in 61-42663, 62-186270, and JP-A-1-316752, the surface of the conductive substrate used in electrophotographic photoreceptors is processed by anodizing or buffing. , or a method of roughening the surface by cutting with a cutting tool, etc., and furthermore, Japanese Patent Application Laid-Open No. 58-17105
No. 59-158, No. 59-204048, No. 6
As described in Japanese Patent No. 0-86550, etc., it has been proposed to eliminate multiple reflections occurring within the photosensitive layer by using a light absorption layer or an antireflection layer between the photosensitive layer and the substrate. There is.

[0005]

However, the previously proposed method of roughening the surface of a conductive substrate has several problems. One of these is that it is difficult to form a rough surface with uniform roughness, and a certain proportion of portions are formed with relatively large roughness. Therefore, the large roughness acts as a carrier injection part into the photosensitive layer, causing white spots during image formation (or appearing as black spots when a reversal development method is used). It became. In other words, in areas where the substrate surface has locally large roughness (protrusions, depressions, etc.) compared to areas with normal surface roughness, when a photosensitive layer is coated on the substrate, The coating thickness is sometimes thinner or thicker than on areas with surface roughness, which causes abnormalities to occur during image formation. Particularly, in the abnormal recessed portion, a major problem is that the coating film of the undercoat layer and/or the charge generation layer loses continuity in the shoulder portion thereof. In other words, in this area, the carrier injection into the photosensitive layer is extremely high, causing white spots (black spots in the reversal development method) during image formation at the beginning of use or during repeated use, resulting in poor image quality. It was a big loss.

[0006] The probability of the existence of such locally large roughness areas, especially abnormal depressions, can be lowered by lowering the average surface roughness over the entire area of the substrate, but as a result, the image It becomes impossible to solve the problem of interference fringe patterns that appear during formation. In other words, although there are various solutions by focusing only on preventing the occurrence of interference fringes, it is extremely difficult to prevent the occurrence of black and white spots on images at the same time as preventing the occurrence of interference fringes. On the other hand, when considering the prevention of black and white spots at the beginning of use and during repeated use, it was not possible to completely prevent the occurrence of interference fringes.

[0007] Therefore, the present invention has been made with the aim of solving the problems of the conventional methods in view of the above-mentioned current situation. That is, an object of the present invention is to simultaneously and completely eliminate the interference fringe pattern that appears during image formation, the appearance of white spots during image formation at the start of use and during repeated use, or the appearance of black spots during reversal development. It is an object of the present invention to provide an electrophotographic photoreceptor that has the following characteristics.

[0008]

[Means for Solving the Problems] The inventors of the present invention have observed the portions of the photoreceptor that significantly impair the image quality, and as a result of intensive study, they have found that the cause is localized large roughness existing on the surface of the substrate. It was discovered that problems occur in image quality when the size of the dent is larger than 10 μm, and the above objective is achieved by making the dent a certain size. They have discovered that it is possible to do this, and have completed the present invention. That is, the present invention is characterized in that in an electrophotographic photoreceptor comprising a photoconductive recording material provided on a conductive substrate, the conductive substrate has a center line average roughness Ra of 0.13 μm or more and a maximum width of the recessed portion. has a rough surface of 10 μm or less.

The present invention will be explained in detail below. In the electrophotographic photoreceptor of the present invention, the conductive substrate includes:
Drums, sheets, etc. of metals and alloys such as aluminum, copper, iron, nickel, zinc, titanium, etc. can be used, and plastic, paper, etc. are used as supports, and after roughening treatment as shown below, It is also possible to use a support whose surface is coated with a metal such as aluminum, titanium, or an alloy thereof by vacuum evaporation. The conductive substrate in the present invention must be roughened so that its surface has a center line average roughness Ra of 0.13 μm or more and a maximum width of the recessed portions of 10 μm or less.

Methods for roughening the surface of the conductive substrate include a method of adjusting the accuracy of surface cutting by cutting, a method of pressing a rotary grindstone, an anodizing method, an etching method, a sandpaper processing method, and a dry method. Honing processing methods, wet honing processing methods, sandblasting processing methods, buffing processing methods, etc. are listed, but among these methods, cutting processing methods and dry or wet honing processing methods require short machining time and are easy to operate. This method is preferred because it is simple, it is easy to obtain the desired surface roughness, and it is stable.

[0011] When adjusting the roughness of the surface cut by cutting, for example, the cylindrical conductive substrate is rotated using a cutting machine such as a milling machine or a lathe using a cutting tool having a V-shaped cutting edge. However, by regularly pressing and moving in a predetermined direction, desired flat groove-like unevenness can be formed.

[0012] Wet honing is a method in which a powdered abrasive is suspended in a liquid such as water and sprayed onto the substrate surface at high speed to roughen the surface. It can be controlled by the blowing pressure, speed, amount, type, shape, size, hardness, specific gravity, suspension temperature, etc. of the abrasive.

Similarly, dry honing is a method of roughening the surface of a conductive substrate by spraying an abrasive with air at high speed, and it is possible to control the surface roughness in the same way as wet honing. can. Examples of the abrasive used in these wet or dry honing treatments include particles of silicon carbide, alumina, iron, glass beads, and the like. In wet or dry honing, in order to reduce the formation of locally large rough areas that cause interference fringes that appear during image formation, for example, the spray speed of the abrasive may be lowered to reduce the unit exposure. A highly preferred method is to increase the treatment time per treatment area. That is, by lengthening the surface roughening treatment time and lowering the spraying speed of the abrasive, the variation in the impact energy of the abrasive on the substrate to be treated is reduced. As a result, the locally rough areas can be reduced compared to the normal rough areas. This method has the following advantages: it is easy to obtain the desired surface roughness, it is stable, and there is no need to introduce new process equipment. The spray speed is determined by the distance between the spray gun and the substrate surface, the compressed air, the nozzle diameter, etc.
By adjusting them, the spraying speed can be controlled.

The undercoat layer provided on the conductive substrate having the roughened surface as described above is formed using a known resin. The thickness of the undercoat layer is 0.05 to 10 μm, especially 0.1 to 2 μm.
It is preferable to set it within the range of . A photosensitive layer is formed on the undercoat layer. When the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer, any of them may be provided on the undercoat layer.

The charge generation layer is made by dispersing a charge generation material in a binder resin, and known charge generation materials can be used as the charge generation material. For example, azo dyes such as chlorodiane blue, quinone pigments such as anthinthrone and pyrenequinone,
Phthalocyanine pigments such as quinocyanine pigments, perylene pigments, perinone pigments, indigo pigments, bisbenzimidazole pigments, copper phthalocyanine and vanadyl phthalocyanine, azulenium salts, squarium pigments, quinacridone pigments, etc. can be used. As the binder resin for the charge generation layer,
Polystyrene resin, polyvinyl acetal resin, acrylic resin, methacrylic resin, vinyl acetate resin, polyester resin, polyarylate resin, polycarbonate resin,
Known materials such as phenolic resin are used.

The charge generation layer is formed by containing a charge generation material in a solution of these binder resins and coating the solution on the undercoat layer. Solvents used for dispersion include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, etc. Any organic solvent can be used. The thickness of the charge generation layer is generally 0.1 to 5 .mu.m, preferably 0.2 to 2.0 .mu.m.

The charge transport layer is made by containing a charge transport material in a binder resin, and the charge transport material includes:
For example, polycyclic aromatic compounds such as anthracene, pyrene, and phenanthrene, or compounds having nitrogen-containing heterocycles such as indole, carbazole, and imidazole, pyrazoline compounds, hydrazone compounds, triphenylmethane compounds, triphenylamine compounds, enamine compounds, Stilbene compounds etc. can be used. The binder resin may be any resin that has film-forming properties, such as polyester, polysulfone, polycarbonate, polymethyl methacrylate, and the like. The charge transport layer is formed by dissolving these binder resins in a solvent and applying a solution in which the above charge transport material is added to the solution to a thickness of 5 to 30 μm. Commonly used solvents include aromatic hydrocarbons such as benzene, toluene, and xylene, ketones such as acetone and 2-butanone, halogenated hydrocarbons such as methylene chloride, monochlorobenzene, and chloroform, tetrahydrofuran, and ethyl ether. Organic solvents can be used.

[0018]

[Examples] The present invention will be explained below with reference to Examples. In addition, all "parts" mean parts by weight.

Examples 1 to 4 An aluminum pipe measuring 1 mm thick x 40 mm φ x 310 mm was prepared and cut using a ground lathe using a diamond cutting tool to finish the surface to a smooth surface with an Ra of 0.04 μm. This aluminum pipe was subjected to surface roughening treatment using a liquid honing device shown in FIG. In FIG. 1, 1 is a base, 2 is a pump, 3 is a gun, 4 is an air introduction pipe, and 5 is a processing container. In the liquid honing process, 10 kg of abrasive (Green Densic GC #400, manufactured by Showa Denko) is suspended in 40 liters of water, and pump 2 pumps the liquid to gun 3 at a flow rate of 6 liters/min. The compressed air pressure was adjusted to the predetermined spray speed shown in Table 1, and the spray was sprayed onto the aluminum pipe. The gun was moved in the axial direction of the aluminum pipe at a speed adjusted to achieve the predetermined processing time shown in Table 1. 37,
The processing times were 80, 240, and 480 seconds/m2, and the moving speeds were 1300, 600, 200, and 100 mm/min, respectively. Also, the aluminum pipe has a speed of 100 rpm.
I rotated it. A methanol/butanol solution of a copolymerized nylon resin (CH8000, manufactured by Toray Industries, Inc.) was applied to each aluminum pipe that had been wet-honed as described above using a ring applicator, and a film thickness of 0.7 μm was applied.
The undercoat layer was formed as a barrier layer.

Next, 3 parts of vanadyl phthalocyanine were dispersed in 70 parts of a 10% cyclohexanone solution of polyester resin (PE100, manufactured by Goodyear Chemical Company). The dispersion operation was performed by mixing the mixture in a ball mill for 2 hours using 10 mm diameter balls. 2 for this
- 10 parts of butanone was added to prepare a coating solution, which was coated onto the barrier layer using a ring coater to form a charge generation layer with a thickness of 0.4 μm. A charge transport layer was formed on the formed charge generation layer. That is, N,N'-diphenyl-N,N
4 parts of '-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine as a charge transport material,
Together with 6 parts of polycarbonate Z resin, it was dissolved in 40 parts of monochlorobenzene, and the resulting solution was applied by a dip coating device at a pull-up speed of 11 cm/min. Dry at 110° C. for 1 hour to form a charge transport layer with a thickness of 20 μm,
An electrophotographic photoreceptor was produced.

Example 5 An electrophotographic photoreceptor was produced in the same manner as in Example 4, except that the surface of the aluminum pipe was roughened by dry honing instead of the wet honing in Example 4. The conditions for the dry honing treatment were the same as in Example 4 except that the abrasive was not suspended in water.

Comparative Examples 1 to 7 Electrophotography was carried out in the same manner as in Example 1, except that the processing time and spraying speed were set to predetermined values shown in Table 1, and wet honing was performed. A photoreceptor was produced.

Comparative Examples 8 and 9 Electrophotography was carried out in the same manner as in Example 1, except that in Example 5, the processing time and spraying speed were set to the predetermined values shown in Table 1, and dry honing was performed. A photoreceptor was produced. In Examples 1 to 5 and Comparative Examples 1 to 9, the surface roughness Ra of the aluminum pipes used as the substrate was measured and observed using an optical microscope. The results are also shown in Table 1.

[0024]

[Table 1] (Note) 1) Wet method. ．． ．． ．． Wet honing, dry honing. ．．
．． ．． Dry honing 2) Local dents of 10 μm or more: ○. ．． ．． ．． Yes, ×. ．． ．． ．． none

The electrophotographic photoreceptors of Examples 1 to 5 and Comparative Examples 1 to 9 were evaluated. That is, the produced electrophotographic photoreceptor was attached to a laser printer (XP-11, manufactured by Fuji Xerox Co., Ltd.), and the output image was examined. The results are shown in Table 2. Table 2 also shows the results of the undercoat layer continuity test. Note that the undercoat layer continuity test was conducted as follows. On the aluminum pipe used in each Example and Comparative Example, only an undercoat layer was formed in the same manner as in each of the above Examples and Comparative Examples, and a 10 mm x 10 mm gold electrode was deposited on the aluminum pipe using a vacuum evaporation device. Ten films were deposited in the axial direction per pipe. A counter electrode was brought into contact with this gold electrode, a power supply voltage of 3 V was applied, and the degree of electrical conductivity was confirmed. Table 2 shows the number of patches showing no conduction among the 10 patches. (The larger the value, the better the film formation properties. In other words, it shows that the undercoat layer is not locally thin or has no unformed parts.)

[0026]

[Table 2] (Note) 1) ○. ．． ．． ．． No occurrence, ×. ．． ．． ．． Occurred 2) Number of patches that did not show continuity

As is clear from the results in Table 2 above, in Examples 1 to 5, no image defects such as interference fringes, white spots, or black spots were observed. Further, no abnormality occurred in the output test of 30,000 sheets. On the other hand, in the case of Comparative Examples 1 and 2, there are many patches that do not show conductivity in the undercoat layer, and no image quality defects such as white spots or black spots are observed, but interference fringe patterns occur in the images. did. In addition, in the case of Comparative Examples 4 and 6 to 9, the surface was sufficiently roughened to eliminate the occurrence of interference fringes, but the number of patches showing conductivity in the undercoat layer was small, and the film formation was difficult. This was not sufficient, and image defects such as white spots and black spots occurred. Moreover, in the case of Comparative Examples 3 and 5, both an interference fringe pattern, white spots, and black spots were generated.

[0028]

Effects of the Invention In the electrophotographic photoreceptor of the present invention, since the roughened conductive substrate surface has the above-mentioned surface condition, the occurrence of interference fringes is prevented and black spots, white spots, etc. Images with good quality can be formed without any image quality defects. Therefore, the electrophotographic photoreceptor of the present invention is suitable for an electrophotographic copying apparatus that utilizes a semiconductor laser, and particularly for an electrophotographic printer that uses a laser beam to perform imagewise line scanning.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a wet honing device used for processing a conductive substrate in the present invention.

[Explanation of symbols]

1. ．． ．． ．． conductive substrate, 2. ．． ．． ．． pump, 3. ．． ．． ．．
Cancer, 4. ．． ．． ．． Air introduction pipe, 5. ．． ．． ．． processing container

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a photoconductive recording layer provided on a conductive substrate, wherein the conductive substrate has a center line average roughness Ra of 0.13 μm or more and a maximum width of a recessed portion of 1 μm.
An electrophotographic photoreceptor characterized by having a rough surface of 0 μm or less.