JP2005195853A - Protection paper for electrophotographic photoreceptor and protection method for electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide protection paper for a cylindrical electrophotographic photoreceptor realizing the reduction of an image defect caused by the protection paper by restraining a flaw such as a pressuring mark whose area is comparatively large but which can not be visually confirmed on the surface of a photoreceptive layer even though the thickness of the protection paper is not increased. <P>SOLUTION: The protection paper to be wound around the outer circumference of the cylindrical electrophotographic photoreceptor has thickness being 0.06 to 0.12mm and length in a winding direction being twice or more times as long as the winding length of the outer circumference of the photoreceptor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a protective paper for a cylindrical electrophotographic photosensitive member mounted on an electrophotographic copying machine, an electrophotographic printer, an electrophotographic facsimile, and a composite machine thereof, and a protection method using the protective paper.

  In cylindrical electrophotographic photoreceptors mounted on electrophotographic apparatuses such as electrophotographic copying machines, electrophotographic printers, electrophotographic facsimiles, and composite machines thereof, in recent years, a photosensitive layer containing an organic photosensitive material has a cylindrical conductive property. An organic electrophotographic photosensitive member (hereinafter simply referred to as an organic photosensitive drum or simply a photosensitive drum) coated on the outer peripheral surface of a substrate is often used. Since the surface hardness of the organic photosensitive drum is not necessarily high, contact marks or scratches due to an object from the outside, including the hands of handling workers and packing means, are easily attached. Since such contact marks affect the image quality, care is required. Furthermore, since exposure to external light also causes deterioration of the photosensitive characteristics due to fatigue, care must be taken especially when light is shielded when replacing the organic photosensitive drum. In consideration of such points, the organic photosensitive drum is usually wound so that a black thin protective paper having a thickness of about 0.1 mm is brought into close contact therewith. In addition to the light-shielding property, black protective paper has an aim to prevent paper discharge by introducing carbon black into the paper to increase paper conductivity and prevent static electricity. is there.

Other examples of such protective paper include a packing sheet (Patent Document 1) in which a light-shielding sheet is attached to a foamed resin sheet, and a protective sheet (Patent Document 2- (0005) paragraph) that does not cause damage to the surface of the photoreceptor by an adhesive tape. ), Black paper to be packed without damaging the surface of the photoreceptor and causing no deterioration in sensitivity (Patent Document 3- (0006) paragraph)), a cushioning material for the photoreceptor with a simple structure (Patent Document 4-Abstract) A method of winding a protective sheet without damaging the surface of the photoreceptor with the edge of paper (Patent Document 5-Abstract) is known.
Japanese Utility Model Publication No. 3-126878 Japanese Utility Model Publication No. 6-50062 JP-A-7-152283 JP-A-8-6436 JP-A-8-16038

  However, the image quality required for an electrophotographic apparatus in the market has also become more important for halftone images, and is particularly severe in monochrome images and color images including halftones. In the evaluation of halftone images, there is no problem with the light shielding performance of the protective paper as in the past, and the photosensitive drum surface can be visually observed in the form of scratches due to the edges of the protective paper, contact marks of high-hardness objects, stress marks, etc. Even when an image defect due to a flaw is not seen, it may be regarded as an image defect. In particular, since there are many halftone output opportunities in a color device, there is a problem that such image defects are likely to occur. As a result of investigating this problem, not only the linear and visible scratches as described above, but also microscopic changes in the photosensitive layer such that the scratches cannot be visually confirmed, such as a relatively large compression mark. The toner adhesion amount changes slightly, and density image unevenness is likely to occur particularly in a halftone image. It has been found that even a monochrome apparatus has a problem when a lot of halftone images are used, and particularly a color apparatus having many halftone images tends to cause image defects. Thus, although it is determined that the image evaluation is defective, the presence of scratches on the drum surface to the extent that the organic photosensitive drum before image evaluation cannot be visually confirmed as defective should be eliminated as much as possible from the cause of the scratches. Needless to say.

  For example, if the thickness of the protective paper is increased, the generation of such scratches can be suppressed. However, since the rigidity of the paper also increases, the rigidity of the start edge of the protective paper is increased. Since the scratches on the drum surface due to the starting edge are more likely to be attached, the paper thickness cannot be increased easily. Furthermore, if the paper thickness is increased, the repulsive force (rewinding force) at the time of winding around the photosensitive drum increases. In that case, it is necessary to increase the adhesive strength of the adhesive tape applied to the end of the protective paper in order to prevent rewinding. In order to increase the adhesive strength, it is conceivable to increase the adhesive strength by increasing the amount of the adhesive or increase the adhesive area. However, in either case, particularly when the protective paper is removed from the photosensitive drum, image defects due to adhesion or penetration of the adhesive to the photosensitive layer are likely to occur, which is still a problem.

  The present invention has been made in view of the above-described points, and is a degree that cannot be visually confirmed on the surface of the photosensitive layer without increasing the thickness of the protective paper, and is like a compression mark having a relatively large area. An object of the present invention is to provide a cylindrical electrophotographic photosensitive member protective paper that can suppress the occurrence of scratches and reduce image defects caused by the protective paper, and a method for protecting an electrophotographic photosensitive member using the protective paper.

  In order to solve the problems and achieve the above object, the present invention is a protective paper for winding around the outer periphery of a cylindrical electrophotographic photosensitive member, and has a thickness of 0.06 mm to 0.12 mm. The protective paper for an electrophotographic photosensitive member has a length in the winding direction of two or more rounds of the outer periphery of the body.

  According to the present invention, in order to solve the problem and achieve the object, it is preferable that the protective paper for electrophotographic photoreceptor according to claim 1 is a black shading paper having conductivity. .

  According to the present invention, in order to solve the problem and achieve the above object, the length of the light shielding paper in the cylindrical axis direction when wound around the cylindrical electrophotographic photosensitive member is larger than the length of the photosensitive member in the cylindrical axis direction. The protective paper for an electrophotographic photosensitive member according to claim 1 or 2 is preferably shorter than the length of the photosensitive layer formed on the outer periphery of the photosensitive member in the cylindrical axis direction.

  According to the present invention, in order to solve the problem and achieve the object, the electrophotographic photosensitive member is mounted on a color electrophotographic apparatus according to any one of claims 1 to 3. It is preferable to use a protective paper for an electrophotographic photoreceptor.

  In order to solve the problems and achieve the above object, the present invention provides a light-shielding paper comprising the protective paper for an electrophotographic photosensitive member according to any one of claims 1 to 4 for a cylindrical electrophotographic photosensitive member. It is preferable to use a method for protecting an electrophotographic photosensitive member in which the end of the light-shielding paper is fixed after being wound two or more times around the outer periphery.

  According to the present invention, even if the thickness of the protective paper is not increased, the surface of the photosensitive layer cannot be visually confirmed, and it is possible to suppress the generation of scratches such as compression marks having a relatively large area. It is possible to provide a protective paper for a cylindrical electrophotographic photosensitive member that reduces image defects caused by paper, and a method for protecting an electrophotographic photosensitive member using this protective paper.

  Hereinafter, the protective paper for an electrophotographic photosensitive member of the present invention and the method for protecting the electrophotographic photosensitive member with the protective paper will be described in detail with reference to the drawings. The present invention is not limited to the examples described below as long as the gist thereof is not exceeded. FIG. 1 is a perspective view showing a protective paper for an electrophotographic photosensitive member according to the present invention and a method for protecting the electrophotographic photosensitive member using the protective paper. FIG. 2 is a front view showing a state in which protective paper is wound around a cylindrical electrophotographic photosensitive member.

As shown in the perspective view of FIG. 1 and the front view of FIG. 2, the organic photosensitive layer 2 is formed on the outer peripheral surface of a cylindrical aluminum alloy substrate 1a having an outer diameter of 30 mm and a length of 254 mm. The protective paper 3 according to the present invention has an axial length of 246 mm to a photosensitive drum 1 that is coated and formed on the central portion of the substrate (within a frame surrounded by a dotted line in FIG. 2) leaving the coating portion. It is 254 mm, completely covers the photosensitive layer 2 of the photosensitive drum 1, and is wound so as not to protrude from the length of the aluminum alloy substrate 1a. That, L ₁ the length of the aluminum alloy substrate 1a, L ₂ the length in the axial direction of the protective paper 3 according to the present invention, when the axial length of the photosensitive layer 2, L _3, L ₃ <L ₂ < L ₁ to become.

  In the present invention, the protective paper 3 is wound two or more times around the outer periphery of the photosensitive drum 1, so that the length of the protective paper 3 in the winding direction is required to be at least 188.5 mm or more in the case of the drum 1 having an outer diameter of 30 mm. Becomes 200 mm or more. After winding, a commercially available adhesive tape (Lintec Super Stick) 4 is attached to the end of the protective paper 3 to prevent the protective paper 3 from unwinding. In the present invention, since the thin protective paper 3 can be used, even if the adhesive tape 4 having a small area and a small amount of glue is used, it is difficult to peel off. The size of the adhesive tape 4 is, for example, 2 cm × 5 cm.

  Usually, after the protective paper 3 according to the present invention is wound around the photosensitive drum 1 and fixed by the adhesive tape 4, resin flanges (not shown) are attached to both ends of the photosensitive drum 1 by fitting. When the photosensitive drum 1 is moved or transported, it is also preferable that a cushion material (not shown) such as an air sheet is wound around the protective paper 3 according to the present invention.

  The protective paper according to the present invention wound around the photosensitive drum 1 (using Conny Black manufactured by Lintec Co., Ltd., and other quality fine paper (black) manufactured by Kishu Paper Co., Ltd. can also be used) 3 has a thickness of 0.06-0. It is a 12 mm thin paper, which has an opaque black color due to the carbon black infiltrated into the paper for light shielding. Further, the carbon black is more conductive than the normal paper due to the action of the carbon black. If the conductivity of the protective paper is increased in this way, it is possible to prevent the occurrence of static electricity due to friction between the protective paper 3 and the photosensitive drum 1, and to prevent the occurrence of discharge defects due to static electricity on the surface of the photosensitive layer 2. preferable. Further, since the protective paper 3 according to the present invention is wound twice around the outer periphery of the photosensitive drum even when the paper is thin, the protective paper 3 has an effect of suppressing contact marks and pressure marks from the outside on the surface of the photosensitive layer 2. Not only that, it is also preferable in terms of light shielding properties. Further, since thin paper can be used, damage to the surface of the photosensitive layer 2 due to the edge of the paper is reduced. In order to confirm the effect of the protective paper 3 according to the present invention described above, the following experiment was performed.

(Explanation of experiment)
The present invention uses a photosensitive drum in which an organic photosensitive layer mainly composed of a charge generating material, a charge transporting material, and a binder resin is formed on a cylindrical aluminum alloy substrate having an outer diameter of 30 mm by dip coating to a thickness of 30 μm. The effect when the protective paper was wound was examined. Regarding image evaluation, evaluation was performed mainly on uneven printing density and halftone images. Evaluation of print density unevenness and halftone image using a color image is a mixed evaluation of colors based on different evaluation criteria for each primary color, which not only complicates the determination of the evaluation result, but also applies the determination result to a monochrome image. Application is not always possible. However, the image evaluation result by the monochrome image can be applied to the color image, and the monochrome mode is the monochrome image itself in the color printer, so the evaluation was performed using the monochrome image. The photosensitive drum was mounted on a commercially available electrophotographic monochrome printer (FS680 manufactured by Kyocera Corporation). Therefore, it can be considered that the image evaluation results obtained in the following experiments are almost the same even when a color device is used.

  By changing the thickness of the protective paper on the photosensitive drum, the number of windings on the drum, the adhesive strength of the adhesive tape, etc., the relationship between these items and the peeling of the adhesive tape and the photosensitive layer from the top of the protective paper will be described later. The effect of pressing stress on the image was investigated.

  For peeling off of the adhesive tape (using Lintec Super Stick), after wrapping the protective paper around the photosensitive drum, fix it with an adhesive tape having two types of strength and weakness so that it will not be rewound. The adhesive tape was peeled after being left.

  In the image evaluation, since the difference was not clear if the printed image such as text was not changed, the exposure light was intentionally reduced by using a neutral density filter, and the print density was intentionally reduced to reveal density unevenness, Evaluation was based on halftone images. At this time, the case where the print density and the halftone image density difference due to the presence or absence of the following pressing stress exceeded the range of ± 5% was determined as an evaluation standard with density unevenness. The print density and image density were measured with a Macbeth densitometer RD910.

A method of pressing stress will be described. A protective paper is wrapped around the photosensitive drum and fixed with an adhesive tape having a size of 2 cm × 5 cm so as not to be rewound, and then a 10 mm × 10 mm rubber piece (close to the hardness of a human finger—JIS A hardness 60 Degree) was pressed from the protective paper perpendicularly to the surface of the photosensitive layer with a force of 1 kg / cm ² , and moved on the surface of 10 mm while being pressed.

(Experimental example 1)
The black protective paper having a thickness of 0.06 mm was wound twice around each of the ten photosensitive drums having an outer diameter of 30 mm, and the terminal portion was fixed with an adhesive tape having low adhesive strength. About five, after applying the predetermined pressing stress from over the protective paper, the protective paper is removed from the photosensitive drum and mounted on the commercially available electrophotographic monochrome printer (FS680 manufactured by Kyocera Corporation). Image formation was performed and image evaluation was performed. The remaining five pieces were left as they were for 200 hours, and the presence or absence of peeling of the adhesive tape was examined.

(Experimental example 2)
Image evaluation and peeling of the adhesive tape were examined in the same manner as in Experimental Example 1 except that the thickness of the black protective paper was changed to 0.08 mm.

(Experimental example 3)
Image evaluation and peeling of the adhesive tape were examined in the same manner as in Experimental Example 1 except that the thickness of the black protective paper was changed to 0.10 mm.

(Experimental example 4)
Image evaluation and peeling of the adhesive tape were examined in the same manner as in Experimental Example 1 except that the thickness of the black protective paper was changed to 0.12 mm.

(Comparative Experimental Example 1)
Image evaluation and peeling of the adhesive tape were examined in the same manner as in Experimental Example 1 except that the thickness of the black protective paper was changed to 0.05 mm.

(Comparative Experiment Example 2)
Image evaluation and peeling of the adhesive tape were examined in the same manner as in Experimental Example 1 except that the number of times the black protective paper was wound around the photosensitive drum was changed to one.

(Comparative Experiment 3)
Image evaluation and peeling of the adhesive tape were examined in the same manner as in Experimental Example 1 except that the thickness of the black protective paper was increased to 0.14 mm.

(Comparative Experimental Example 4)
The image evaluation and peeling of the adhesive tape were examined in the same manner as in Experimental Example 1 except that the thickness of the black protective paper was increased to 0.16 mm and the terminal portion was changed to an adhesive tape having high adhesive strength and fixed. . The results of the experiment described above are shown in Table 1 below.

  According to Table 1, in Experimental Examples 1 to 4, since the protective paper according to the present invention is wound around the electrophotographic photosensitive member by the protective method according to the present invention, there is no peeling of the adhesive tape, and a predetermined amount is applied from above the protective paper. It can be seen that the image does not become defective even when this pressure is applied.

  On the other hand, in Comparative Experimental Example 1, the thickness of the protective paper is too thin, and an image defect due to pressing stress occurs even when the protective paper is wound twice around the photosensitive drum. In Comparative Experimental Example 2, it can be seen that, when compared with Experimental Example 1, when the number of windings is reduced to one round, an image defect due to pressing stress occurs even if the other conditions are the same. In Comparative Experimental Example 3, it can be seen that if the protective paper is too thick as 0.14 mm, if the adhesive strength of the adhesive tape is weak, peeling failure of the adhesive tape occurs in 200 hours after fixing with the adhesive tape. In one of the five photosensitive drums subjected to image evaluation, a visible scratch that seems to be due to the starting end portion was also generated. In Comparative Experimental Example 4, since the protective paper was further thickened to 0.16 mm, defective peeling of the adhesive tape occurred in 200 hours after fixing with the adhesive tape even when the adhesive strength of the adhesive tape was increased. Further, in three of the five photosensitive drums subjected to the image evaluation, visible scratches that were thought to be due to the starting end portion were also generated.

FIG. 3 is a perspective view showing a state in which the electrophotographic photosensitive member protective paper according to the present invention is wound around the electrophotographic photosensitive member. FIG. 3 is a front view showing a state in which the electrophotographic photosensitive member protective paper according to the present invention is wound around the electrophotographic photosensitive member.

Explanation of symbols

1 Electrophotographic photoreceptor (photosensitive drum)
1a Aluminum alloy substrate 2 Photosensitive layer 3 Protective paper for electrophotographic photosensitive member (light-shielding paper)
4 Adhesive tape

Claims (5)

  A light-shielding paper for winding around the outer periphery of a cylindrical electrophotographic photosensitive member, having a thickness of 0.06 mm to 0.12 mm and having a winding direction length of two or more rounds of the outer periphery of the photosensitive member. Protective paper for electrophotographic photoreceptors.   2. The protective paper for an electrophotographic photosensitive member according to claim 1, wherein the protective paper is a black shading paper having conductivity.   The length of the light shielding paper in the cylindrical axis direction when wound around the cylindrical electrophotographic photosensitive member is shorter than the length of the photosensitive member in the cylindrical axial direction, and the length of the photosensitive layer formed on the outer periphery of the photosensitive member in the cylindrical axial direction. 3. The protective paper for an electrophotographic photosensitive member according to claim 1, wherein the protective paper is longer than the length.   The protective paper for an electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the electrophotographic photosensitive member is mounted on a color electrophotographic apparatus.   A light-shielding paper comprising the protective paper for an electrophotographic photosensitive member according to any one of claims 1 to 4 is wound around the outer periphery of a cylindrical electrophotographic photosensitive member two or more times, and then the end of the light-shielding paper is fixed. A method for protecting an electrophotographic photosensitive member.

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