GB2250608A

GB2250608A - Surface machining method for electrophotographic photoconductor

Info

Publication number: GB2250608A
Application number: GB9122851A
Authority: GB
Inventors: Sadahiko Shimosawa; Hideki Konno; Yoshihiro Hosono
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1990-10-26
Filing date: 1991-10-28
Publication date: 1992-06-10
Anticipated expiration: 2011-10-28
Also published as: GB2250608B; GB9122851D0

Abstract

A method of removing a surface portion of an electrophotographic photoconductor comprises blasting the surface portion with a mixture of solid particles and a liquid. This method can be used to peel off a photoconductive layer or a protective layer on the photoconductor or to machine or roughen the surface portion of such a layer or the conductive support of the photoconductor. Preferably glass beads or ceramic particles in a jet of water are used for blasting.

Description

SURFACE MACHINING METHOD FOR ELECTROPHOTOGRAPHI C PHOTOCONDUCTOR The present invention relates to a surface machining method for an electrophotographic photoconductor by removing a surface portion thereof, more particularly by peeling a surface layer from the electrophotographic photoconductor or machining a surface portion thereof, which method comprises a step of blasting the surface portion thereof with a mixture of solid particles and a liquid.

Used or defective electrophotographic photoconductors are now recycled in such a fashion that a photoconductive layer is peeled from an electroconductive support because the cost of such electrophotographic photoconductors is high.

In the case where a selenium-type photoconductor is prepared, a protective layer is further overlaid on a photoconductive layer to improve the chargeability, durability and moisture-resistance of the photoconductor.

Such a protective layer is as thin as 1 to 10 urn, so that there is difficulty in forming the protective layer, which decreases the yield. When the protective layer cannot be properly formed on the photoconductive layer, therefore, it is necessary to peel the defective protective layer from the photoconductive layer and to try to again form a satisfactory protective layer.

For recycling the photoconductor, the photoconductive layer is conventionally peeled from the electroconductive support by the following methods.

(1) Solvent immersing method: the photoconductor is immersed in an organic solvent such as heated trichloroethylene, so that the thermal expansion of the photoconductive layer is made to differ from that of the support, or crystallization is caused in the photoconductive layer Thus, the photoconductive layer can be peeled from the electroconductive support.

(2) Coolant immersing method: the photoconductor is immersed in an excessively low temperature liquid such as liquid nitrogen to make the heat shrinkage of the photoconductive layer different from that of the electroconductive support, thereby peeling the photoconductive layer from the support.

(3) Water jet method: the photoconductive layer can be peeled from the electroconductive support by directing a jet of hot water onto the photoconductive layer at high pressure.

However, the above-mentioned peeling methods have the following respective shortcomings. For instance, when the method (1) is employed, the solvent cannot easily be separated from the peeled material contained therein, so that recovery of the solvent is difficult. In addition, the use of the solvent applicable to the method (1) is restricted.

The method (2) cannot be applied to peel away a photoconductive layer of an As-Se type photoconductor or a photoconductor in which an electroconductive support has been subjected to chemical etching to form a photoconductive layer thereon. In addition, the remarkably low temperature liquid used, such as liquid nitrogen, vigorously vaporizes when the photoconductor is merely immersed therein, so that great quantities of the low temperature liquid are required.

To peel the photoconductive layer from the electroconductive support by the method (3), it is required to spray the hot water onto the photoconductive layer at a pressure as high as 2000 kg/cm2 because the conditions for depositing the photoconductive layer on the support are changed to increase the adhesion between the photoconductive layer and the support, with the prevention of pinholes generated in the photoconductive layer taken into consideration This is accompanied by noise, and it is necessary to repeat the process of spraying the hot water onto the photoconductive layer at high pressure in order to completely peel the photoconductive layer from the support.

Furthermore, in this method, the exposed surface needs cleaning, and the peeled material cannot easily be separated from the water.

For peeling only the protective layer from the photoconductive layer, the protective layer may be immersed in the same solvent as that used to disperse a resin therein in forming the protective layer When a polymerizable curing-type resin is used for preparation of a protective layer for improving the durability as disclosed in Japanese Laid-Open Patent Application 1-66661, however, the protective layer of this type cannot be peeled from the photoconductive layer by the solvent immersion method. When the water jet method is applied to peel away this type of protective layer, the photoconductive layer is also in danger of being impaired. In addition, a method for peeling off the protective layer by heating the photoconductor may cause the photoconductive characteristics of the photoconductor to deteriorate.

Meanwhile, it is important to machine the surface portion of the electrophotographic photoconductor to a desired value in order to obtain high quality images. When there are concave and convex portions on the surface of the photoconductor, black spots appear on the white background or white spots appear on the black solid image. In addition, when a cleaning blade in contact with the photoconductor is scratched by the convex portion of the surface of the photoconductor, a black stripe appears on a sheet of copy paper corresponding to the circumferential direction of the photoconductor. In contrast to this, if the surface of the photoconductor is excessively smooth, a toner cannot be stabilized on the photoconductor, which accordingly yields non-uniform images.

Not only the surface profile of the photoconductor, but also that of the electroconductive support is a key point in preparing a satisfactory photoconductor. This is because the surface profile of the support has a serious effect on the formation of the photoconductive layer thereon and thus, determines the quality of obtained images.

When the surface of the electroconductive support is too rough, the heat radiation of the support is increased, so that the temperature thereof is lowered in forming the photoconductive layer on the electroconductive support by vacuum-deposition. As a result, a predetermined thickness of photoconductive layer cannot be obtained and the desired smoothness of the photoconductor cannot be obtained.

When the surface of the support is extremely smooth, on the other hand, the adhesion strength of the photoconductive layer to the support is decreased, so that the photoconductive layer is readily peeled from the support.

In addition, when foreign materials are attached to the surface of the electroconductive support, this affects the appearance of the electrophotographic photoconductor even after the photoconductive layer is overlaid on the support.

Thus, black spots or white spots also appear on the copy paper To eliminate the aforementioned shortcomings, the surface layer or the electroconductive support of the photoconductor is conventionally subjected to superfinishing by buffing, honing and water jetting in order to obtain an appropriate roughness.

It is necessary to clean the surface layer of the photoconductor to remove the abrasive grains therefrom by a solvent such as trichloroethylene or Freon after subjected to superfinishing by buffing and honing. However, the use of these kinds of solvents is restricted, and foreign materials are newly deposited on the surface layer in the case where the drying conditions are improper after cleaning. This also has an adverse effect on the quality of obtained images.

When the electroconductive support is subjected to surface treatment by buffing or honing, the use of a solvent of this kind for use in the cleaning process is restricted as previously mentioned. The water-jet method generates noise, and causes the problem of embedding of foreign materials in the support. Consequently, it is difficult to uniformly roughen the surface of the electroconductive support.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method of peeling a photoconductive layer from an electroconductive support without scratching the support, or peeling a protective layer from the photoconductive layer without scratching the photoconductive layer; and a method of machining the surface layer of the electrophotographic photoconductor and the surface of the electroconductive support, without foreign materials attached thereto.

The above-mentioned object of the present invention can be achieved by a method of removing a surface portion of an electrophotographic photoconductor, comprising a step of blasting the surface portion thereof with a mixture of solid particles and a liquid.

The method of removing the surface portion of an electrophotographic photoconductor according to the present invention by spraying the mixture of solid particles and the liquid onto the surface portion thereof is more effective than the conventional water-jet method because a large impact can be applied to the surface portion of the photoconductor by low mechanical power.

BRIEF~DESCRIPTION OF THE DRAWINGS A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:: Fig 1 is a schematic view of an embodiment of an apparatus for removing a surface portion of the electrophotographic photoconductor by blasting the surface portion thereof with a mixture of solid particles and a liquid; Figs. 2(a) to 2(c) are schematic cross-sectional views of a photoconductor, which illustrate the procedure for peeling a photoconductive layer from an electroconductive support using the apparatus as shown in Fig. 1; Figs. 3(a) to 3(c) are schematic cross-sectional views of a photoconductor, which illustrate the procedure for peeling a protective layer from a photoconductive layer using the apparatus as shown in Fig. 1; Fig. 4 is a schematic cross-sectional view, which illustrates the process of roughening a photoconductive layer of a photoconductor using the apparatus as shown in Fig. 1;; Fig. 5 is a schematic cross-sectional view, which illustrates the process of roughening the surface of an electroconductive support using the apparatus as shown in Fig. 1; Fig. 6 is a graph showing the relationship between the time required to peel off a photoconductive layer and the pressure of a mixture of solid particles and a liquid applied to the photoconductive layer as shown in Example 1; and Fig. 7 is a graph showing the relationship between the pressure of a mixture of solid particles and a liquid applied to an electroconductive support and the obtained surface roughness thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of removing a surface portion of an electrophotographic photoconductor according to the present invention can be applied to two cases; one is for peeling a photoconductive layer from an electroconductive support, or a protective layer from a lower layer such as the photoconductive layer, and the other is for machining a surface portion of an electrophotographic photoconductor.

The case where the method of the present invention is applied to peel the photoconductive layer from the electroconductive support of an electrophotographic photoconductor will first be explained in detail by referring to Fig. 1.

The used or defective photoconductive layer is peeled from the support in an apparatus as shown in Fig. 1, for the purpose of recycling the support and a photoconductive material for use in the removed photoconductive layer The apparatus shown in Fig. 1 is composed of a container 2 in which the used or defective photoconductive layer of a photoconductor 1 is peeled from the support; a mechanism for transporting a mixture 5 of solid particles 6 and a liquid; a mechanism for spraying the mixture 5 onto the photoconductive layer of the photoconductor 1; a mechanism for rotating the photoconductor 1 which is secured by flanges; and a mechanism for moving a nozzle 9 through which the mixture 5 is blown over the photoconductive layer of the photoconductor 1.

In Fig. 1, the photoconductor 1 is placed in the container 2 through an opening 3 and secured in a predetermined position by a pair of flanges. The photoconductor 1 is driven by a motor 4 to rotate in the direction of the arrow. The mixture 5 of a liquid and solid particles 6 is transported through a mixture transporting pipe 8 to the nozzle 9 by a pump 7, and at the same time, air is caused to flow into the mixture 5 through an air hose 10. The mixture 5 is finally caused to spray from the nozzle 9 onto the photoconductive layer of the photoconductor 1. Thus, the solid particles 6 come into collision with the photoconductive layer of the photoconductor 1, thereby physically breaking down the photoconductive layer with the solid particles 6. Consequently, the photoconductive layer is peeled from the support. Since the nozzle 9 is driven by a nozzle driving motor 11 so as to move up and down along a nozzle transporting shaft 12, the mixture 5 can be uniformly applied to the entire photoconductive layer.

As previously mentioned, the nozzle 9 is caused to eject the mixture 5 of the solid particles 6 and the liquid toward the photoconductor 1. In this case, the nozzle may be disposed so that the mixture 5 being sprayed from the nozzle 9 can be directed to the rotating shaft of the photoconductor 1, namely, perpendicular to a tangent of the photoconductor 1. Alternatively, the nozzle 9 may be disposed so as to spray the mixture 5 in the tangential direction of the photoconductor 1. In addition, a plurality of nozzles may be secured to the nozzle transporting shaft 12, parallel to the shaft of the photoconductor 1 instead of causing one nozzle to move up and down.

As the solid particles 6 of the mixture 5 for use in the present invention, ceramic powder and glass beads are preferable because they can easily be separated from the photoconductive material of the photoconductive layer which is peeled off.

It is preferable that the diameter of the solid particles 6 be 500 urn or less, and more preferably 75 to 500 urn. When the diameter of the solid particles 6 is 500 urn or less, the energy for spraying the mixture containing such solid particles onto the photoconductor is not very large, therefore it is not necessary to excessively increase the capacity of the pump 7, as shown in Fig. 1. In addition, the solid particles with a particle diameter of 500 urn or less can easily be mixed with the liquid, so that a uniformly-dispersed mixture can be prepared. Accordingly, the photoconductive layer can be peeled from the support uniformly.Furthermore, since the solid particles with a particle diameter of 500 urn or less do not crack in practice, the solid particles always retain their uniform shape. Therefore, the surface of the electroconductive support which is exposed by removing the photoconductive layer therefrom can be kept smooth even though the solid particles are repeatedly used for peeling the photoconductor from the support.

When the ratio by volume of the solid particles to the liquid is in the range from about 1:4 to 1:7, the photoconductive layer can be peeled from the electroconductive support without scratching the support.

Water is preferably used as the liquid for preparing the mixture because the solid particles contained in the mixture can easily be separated from the photoconductive material of the peeled photoconductive layer.

The pressure of the mixture of the solid particles and the liquid applied to the photoconductor may be appropriately determined so as to completely peel the photoconductive layer from the electroconductive support without damaging the support.

Using the apparatus shown in Fig. 1, a photoconductive layer is peeled from an electroconductive support as shown in Figs. 2(a) to 2(c). An electrophotographic photoconductor as shown in Fig. 2(a) comprises an electroconductive support 13 and a photoconductive layer 14 formed thereon.

As shown in Fig. 2(b), when solid particles 6 contained in a mixture 5 collide with the surface of the photoconductive layer 14, a dent 15 and a crack 16 are successively formed.

Finally, the photoconductive layer 14 is removed from the electroconductive support 13 without scratching the support 13 as shown in Fig. 2(c). After removal of the photoconductive layer 14, the solid particles 6 are not attached to the surface of the electroconductive support 13, and in addition, the mixture 5 containing the solid particles 6 can be recovered for recycling. By forming a new photoconductive layer on the electroconductive support as shown in Fig. 2(c), the electroconductive support can be used repeatedly.

According to the method of removing the photoconductive layer from the electroconductive support of the present invention, the electroconductive support receives no scratches. This is because the mixture of the solid particles and the liquid is applied to the surface of the photoconductor and the solid particles come into collision with the surface portion of the photoconductor. The pressure of the mixture applied to the photoconductor is lower than that by the water-jet method. By the collision with the solid particles, the photoconductive layer is peeled away in fine pieces. Therefore, the surface of the electroconductive support is not scratched during the removal of the photoconductive layer.In contrast to the above, relatively large pieces of the photoconductive layer peeled off by the water-jet method are unfavorably thrust through the electroconductive support under high pressure.

In the case where a protective layer is improperly coated, the protective layer only can be peeled from the lower layer using the apparatus shown in Fig. 1, in accordance with the procedure shown in Figs. 3(a) to 3(c).

An electrophotographic photoconductor as shown in Fig. 3(a) comprises an electroconductive support 17, a photoconductive layer 18 formed thereon, and a protective layer 19 formed on the photoconductive layer 18.

For solid particles 21 contained in a mixture 20, particles with a relatively low hardness such as powdered cork are preferably employed to prevent the photoconductive layer 18 from being scratched. The diameter of the solid particles 21 and the pressure of the mixture 20 applied to the protective layer 19 maybe appropriately determined in such a degree that only the protective layer 19 is removed from the photoconductive layer 18 without scratching the photoconductive layer 18 formed thereunder, and in addition, so that the exposed photoconductive layer 18 has a proper surface roughness for coating a new protective layer thereon. As the liquid for use in the mixture 20, water is also preferably employed.

For peeling the protective layer 19 from the photo conductive layer 18, it is preferable that the mixture 20 of the solid particles 21 and the liquid be sprayed tangentially to the protective layer 19 in the cylindrical form in order to avoid scratching the photoconductive layer 18.

When the mixture 20 containing the solid particles 21 are sprayed onto the protective layer 19 under the abovementioned conditions, the solid particles 21 contained in the mixture 20 come into collision with the surface of the protective layer 19, and a dent 22 and a crack 23 are successively formed as shown in Fig. 3(b). Finally, the protective layer 19 only is easily removed from the photoconductive layer 18 without scratching or impairing the photoconductive layer 18 as shown in Fig 3(c). After removal of the protective layer 19 from the photoconductive layer 18, the solid particles 21 are not attached to the surface of the photoconductive layer 18, and in addition, the mixture 20 containing the solid particles 21 can be recovered for recycling. More specifically, pieces of the peeled protective layer 19 contained in the mixture 20 of the solid particles 21 and the liquid are lighter than the solid particles 21 in weight, so that the pieces of the removed protective layer can be separated by a separator.

Thus, the solid particles 20 can be recovered and repeatedly used. By forming a new protective layer on the photoconductive layer, the photoconductive layer 18 and the electroconductive support 17 can be repeatedly used.

The case where the method of the present invention is applied to machine a surface portion of an electrophotographic photoconductor will now be explained in detail.

According to the method of the present invention, a surface layer such as a photoconductive layer, or an electroconductive support of the electrophotographic photoconductor can be made rough to a predetermined value, for instance, using the apparatus as shown in Fig. 1, based on the same principle as that in peeling off the photoconductive layer or protective layer as previously mentioned.

Fig. 4 is a schematic view illustrating the process of machining a photoconductive layer by the method of the present invention.

In Fig. 4, the same solid particles as those used for peeling the photoconductive layer from the electroconductive support as explained in Figs. 2(a) to 2(c) are preferably used as solid particles 28. The diameter of the solid particles 28 and the pressure of a mixture 27 applied to a photoconductive layer 25, which is formed on an electroconductive support 24, may be appropriately determined in such a degree that only the surface portion of the photoconductive layer 25 is machined without impairing the photoconductive layer 25 itself. As a liquid for use in the mixture 27, water is also preferred.

When the mixture 27 of the solid particles 28 and the liquid is sprayed from a nozzle 26 onto the surface of the photoconductive layer 25 under the above-mentioned conditions, the surface portion of the photoconductive layer 25 can be machined so as to have a predetermined surface roughness 29, with the solid particles 28 being not attached to the surface of the photoconductive layer 25. This is accompanied by preparation of an electrophotographic photoconductor which is capable of yielding high quality copied images. In addition, the mixture 27 containing the solid particles 28 can be recovered and repeatedly used after the surface portion of the photoconductive layer is once machined.

According to the method of the present invention, an electroconductive support of the electrophotographic photoconductor can be made rough to a predetermined value, for instance, using the apparatus as shown in Fig. 1, based on the same principle as that in peeling off the photoconductive layer or protective layer as previously mentioned.

Fig. 5 is a schematic view illustrating the process of machining an electroconductive support by the method of the present invention.

In Fig. 5, the same solid particles as those used for roughening the photoconductive layer are preferably used as solid particles 33. The diameter of the solid particles 33 and the pressure of a mixture 32 applied to an electroconductive support 30 may be appropriately determined in such a degree that only the surface portion of the electroconductive support 30 is machined. As a liquid for use in the mixture 32, water is also preferred.

When the mixture 32 of the solid particles 33 and the liquid is sprayed from a nozzle 31 onto the surface of the electroconductive support 30 under the above-mentioned conditions, the surface portion of the support 30 can be machined so as to have a predetermined surface roughness 34, with the solid particles 33 being not attached to the surface of the electroconductive support 30. As a result, a photoconductive layer can be stably formed on such a surface treated electroconductive support, and the thus prepared electrophotographic photoconductor is capable of yielding high quality copied images.

Other features of this invention will become apparent in the course of the following description of exemplary embodiments, which are given for illustration of the invention and are not intended to be limiting thereof.

Example 1 The used electrophotographic photoconductor with a diameter of about 80 mm comprising an As-Se photoconductive layer with a thickness of about 60 urn was installed in an apparatus as shown in Fig. 1. This photoconductor was driven to rotate at 50 rpm.

A mixture of tap water and ceramic powder with an average particle diameter of 125 urn or less was placed in the apparatus shown in Fig. 1, and the photoconductive layer of the photoconductor was blasted by spraying the above mixture thereonto at a pressure of 50 psi, with moving a nozzle at a speed of 100 mm/min parallel to the rotating shaft of the photoconductor. Thus, the As-Se photoconductive layer was peeled from an electroconductive support, without scratching the support.

Fig. 6 is a graph showing the relationship between the time required to peel off the As-Se photoconductive layer for use in Example 1 and the pressure of a mixture of solid particles and a liquid applied to this photoconductive layer, with increasing the pressure of the mixture from 25 psi to 55 psi by 5 psi.

Example 2 The same electrophotographic photoconductor as employed in Example 1 was installed in an apparatus as shown in Fig.

1. This photoconductor was driven to rotate at 200 rpm.

A mixture of tap water and glass beads with a particle diameter of 50 to 300 um was placed in the apparatus as shown in Fig. 1, and the photoconductive layer of the photoconductor was blasted by spraying the above mixture thereonto at a pressure of 30 psi, with moving a nozzle at a speed of 200 mm/min parallel to the rotating shaft of the photoconductor. Thus, the As-Se photoconductive layer was peeled from an electroconductive support, without scratching the support.

Example 3 The used electrophotographic photoconductor with a diameter of about 80 mm comprising a Se-Te photoconductive layer with a thickness of about 60 urn was installed in an apparatus as shown in Fig. 1. This photoconductor was driven to rotate at 100 rpm.

A mixture of tap water and ceramic particles with an average particle diameter of 75 urn or less was placed in the apparatus as shown in Fig. 1, and the photoconductive layer of the photoconductor was blasted by spraying the above mixture thereonto at a pressure of 20 psi, with moving a nozzle at a speed of 100 mm/min parallel to the rotating shaft of the photoconductor. Thus, the Se-Te photoconductive layer was peeled from an electroconductive support, without scratching the support.

Since the hardness of the Se-Te photoconductive layer is smaller than that of the As-Se photoconductive layer, the Se-Te photoconductive layer was appropriately removed by reducing the pressure of the sprayed mixture of tap water and ceramic particles.

The peeling performance of the photoconductive layer in Examples 1 to 3 are shown in Table 1.

In Examples 1 to 3, a new photoconductive layer was separately formed on the electroconductive support by the conventional method after removal of the used photoconductive layer Each of the thus prepared electrophotographic photoconductors was placed in a commercially available plain paper copier to evaluate the quality of copied images. The results are also given in Table 1.

Table 1

Example No. 1 2 3 Photo conductive As-Se As-Se Se-Te Layer Solid Particles Ceramic powder Glass beads Ceramic powder Particle Diameter of Solid 125 urn or less 50 to 300 urn 75 urn or less Particles Pressure 50 psi 30 psi 20 psi Rotational Speed of Photo- 50 rpm 200 rpm 100 rpm conductor Moving Speed of 100 mm/min, '200 mm/min. 100 mm/min.

Nozzle Peeling Performance Excellent Excellent Excellent Image Quality of Copied Excellent Excellent Excellent Images Example 4 An electroconductive support made of an alloy (A3003) was installed in an apparatus as shown in Fig. 1. This electroconductive support was driven to rotate at 50 rpm.

A mixture of tap water and ceramic particles with an average particle diameter of 125 urn or less was placed in the apparatus as shown in Fig. 1, and the electroconductive support was blasted by spraying the above mixture thereonto at a pressure of 40 psi, with moving a nozzle at a speed of 100 mm/min parallel to the rotating shaft of the electroconductive support. Thus, the electroconductive support was finished to have a surface roughness of 4.5 urn Rz (ten-point mean roughness in accordance with JIS B 0601).

Fig. 7 is a graph showing the relationship between the pressure of a mixture of ceramic powder and water applied to the electroconductive support and the obtained surface roughness of the electroconductive support, using two kinds of ceramic powder, one having an average particle diameter of 125 urn or less employed in Example 4 and the other having an average particle diameter of 75 urn or less As can be seen from the graph in Fig. 7, the surface roughness can be freely controlled by changing the pressure of the mixture applied to the electroconductive support.

Example 5 An electroconductive support made of an alloy (A1050) was installed in an apparatus as shown in Fig. 1. This electroconductive support was driven to rotate at 50 rpm.

A mixture of tap water and ceramic particles with an average particle diameter of 125 urn or less was placed in the apparatus as shown in Fig. 1, and the electroconductive support was blasted by spraying the above mixture at a pressure of 20 psi, with moving a nozzle at a speed of 150 mm/min parallel to the rotating shaft of the electroconductive support. Thus, the electroconductive support was finished to have a surface roughness of 3.0 urn Rz (ten-point mean roughness in accordance with JIS B 0601).

As previously mentioned, according to the method of the present invention, the photoconductive layer can be easily peeled from the electroconductive support without scratching the support, or the protective layer can also be peeled from the photoconductive layer without scratching the photoconductive layer. In peeling off the above-mentioned surface layers of the electrophotographic photoconductor, no foreign substance is attached to the exposed surface after removal of the surface layer, so that the remaining part of the photoconductor can be recycled, which can decrease the manufacturing cost. In addition, since the surface portion of the photoconductor is blasted with the mixture of solid particles and the liquid, pieces of the removed layer are not scattered, and the solid particles can be recovered for recycling. Furthermore, the surface portion of the photoconductor is blasted with the mixture of the solid particles and the liquid at a lower pressure as compared with the case where the water-jet method is employed, thereby decreasing noise.

In addition, a surface portion of the electrophotographic photoconductor can be machined in accordance with the method of the present invention. For example, the photoconductive layer or the electroconductive support can be finished to have a predetermined surface roughness with no foreign substance being attached to the surface thereof.

Thus, electrophotographic photoconductors capable of yielding high quality images can be prepared repeatedly.

Claims

Claims:

1. A method of removing a surface portion of an electrophotographic photoconductor, comprising the step of blasting said surface portion thereof with a mixture of solid particles and a liquid.

2. A method as claimed in claim 1, wherein the solid particles have a particle diameter of 500 sm or less.

3. A method as claimed in claim 1 or claim 2, wherein the ratio by volume of the solid particles to the liquid is from 1:4 to 1:7.

4. A method as claimed in any one of the preceding claims wherein the surface portion is a photoconductive layer of the electrophotographic photoconductor.

5. A method as claimed in any one of claims 1-3 wherein the surface portion is a protective layer of the electrophotographic photoconductor.

6. A method of machining a surface portion of an electrophotographic photoconductor, comprising the step of blasting the surface portion thereof with a mixture of solid particles and a liquid.

7. A method as claimed in claim 6, wherein the solid particles have a particle diameter of 500 Fm or less.

8. A method as claimed in claim 6 or claim 7, wherein the surface portion is a photoconductive layer of the electrophotographic photoconductor.

9. The method as claimed in claim 6 or claim 7, wherein the surface portion is an electroconductive support of the electrophotographic photoconductor.

10. A method as claimed in claim 1 substantially as hereinbefore described.