JP5302601B2 - Manufacturing method of charging roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of advantageously manufacturing a charging roll exhibiting excellent durability. <P>SOLUTION: The method includes: a step of preparing a rubber tube made of ion conductive rubber material, vulcanizing the same under a predetermined condition to form a semi-cure rubber tube, and subsequently disposing the semi-cure rubber tube in a molding cavity of a mold; a step of concentrically disposing a shaft in the molding cavity to fill a gap formed between the shaft and the semi-cure rubber tube with unvulcanized non-foam rubber material to thereby form a roll precursor having an unvulcanized rubber layer made of non-foam rubber material giving a non-foam elastic layer 14 in the periphery of the shaft and having a semi-cure rubber layer made of the semi-cure rubber tube giving a resistance adjusting layer 16 on the outside thereof; and a step of subsequently vulcanizing the roll precursor to complete vulcanization of the unvulcanized rubber layer and the semi-cure rubber layer to thereby form a non-foam elastic layer and a resistance adjusting layer. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a charging roll used for charging an image carrier made of an electrophotographic photosensitive member or an electrostatic recording dielectric in an image forming apparatus such as a copying machine, a printer, or a facsimile using an electrophotographic method. It relates to a process which can be advantageously produced.

  2. Description of the Related Art Conventionally, in an image forming apparatus (hereinafter referred to as an electrophotographic apparatus) such as a copying machine, a printer, and a facsimile using an electrophotographic method, an image carrier such as an electrophotographic photosensitive member (photosensitive drum) is attached to the outer periphery of a charging roll. A so-called roll charging method is used in which the surface of the image carrier is charged by contacting the surface and rotating the image carrier and the charging roll relative to each other.

  In addition, as a charging roll used in such a roll charging method, those having various structures are conventionally used. For example, on the outer peripheral surface of a shaft body (core metal) serving as a roll shaft. A non-foaming elastic layer made of a non-foaming conductive rubber material is integrally provided with a predetermined thickness, and an ionic conductivity containing an ionic conductive agent outside the non-foaming elastic layer. A roll in which a resistance adjusting layer made of a rubber material is integrally provided and a protective layer made of a semiconductive resin material is provided as an outermost layer is used as a charging roll.

  By the way, in recent years, there has been an increasing need for longer life for electrophotographic equipment such as copying machines, and charging rolls, which are one of the important functional parts in electrophotographic equipment, are also required to have higher durability than before. It has been.

  Under such circumstances, research on increasing the durability of the charging roll having the above-described configuration is underway. However, for the charging roll having such a configuration, the ionic conductivity contained in the resistance adjustment layer is long-time energized. It is known that the agent decreases, thereby increasing (deteriorating) the resistance (roll resistance) of the entire roll and deteriorating roll performance.

  That is, the charging roll is brought into contact with an image carrier such as a photosensitive drum in a state where a voltage is applied, and the photosensitive drum or the like is charged. By energizing the charging roll and the photosensitive drum, The ionic conductive agent contained in the resistance adjustment layer gradually precipitates out of the resistance adjustment layer and reacts with other compounds to change into an insulator. For this reason, it is inevitable that the charging roll having the above-described configuration is accompanied by a decrease in the ionic conductive agent in the resistance adjusting layer and an increase in the resistance of the entire roll (roll resistance). If the resistance exceeds the allowable value of the power source that is responsible for applying the voltage to the charging roll, it will not be possible to apply a voltage sufficient to charge the photosensitive drum or the like. And a roll with such a large roll resistance can no longer be used as a charging roll.

  In order to prevent deterioration of roll performance due to the decrease of the ionic conductive agent in the resistance adjustment layer, by adding a large amount of ionic conductive agent to the ionic conductive rubber material that provides the resistance adjustment layer in the roll manufacturing stage. It is conceivable to increase the proportion of the ionic conductive agent in the resistance adjustment layer. However, if a large amount of ionic conductive agent is present in the resistance adjustment layer, problems such as bloom (powder blowing) may occur, so there is an upper limit for increasing the proportion of the ionic conductive agent in the resistance adjustment layer. is there.

  On the other hand, the mixing ratio of the ionic conductive agent in the ionic conductive rubber material is the same as in the past, and the thickness of the resistance adjusting layer obtained by using it is made thicker than that of the conventional charging roll. Although it is conceivable to prevent the roll performance from deteriorating as described above, the conventional method for producing a charging roll has the following problems in providing a thick resistance adjusting layer made of an ion conductive rubber material. .

  That is, as one method for producing a resistance adjustment layer using an ion conductive rubber material, first, a roll body in which a non-foaming elastic layer is provided on the outer peripheral surface of a cored bar that is a conductive shaft body. On the other hand, a coating liquid is prepared by adding an ionic conductive agent, an ionic conductive rubber or the like to a predetermined organic solvent, and according to various conventionally known roll coating methods (see Patent Document 1), A technique is known in which a coating liquid layer is formed by repeatedly applying a coating liquid on the surface of a foamable elastic body layer), and after the application is completed, the coating liquid layer is dried to form a resistance adjusting layer. However, in such a roll coating method, in order to increase the thickness of the finally obtained resistance adjustment layer, it is necessary to increase the number of times of application when increasing the thickness of the coating liquid layer. There is a problem that the production efficiency is deteriorated, and there is also a problem that it is relatively difficult to control the thickness of the coating liquid layer to be uniform.

  As another technique, a vulcanized rubber tube formed using an ion conductive rubber material is placed in a molding cavity of a mold, while an unvulcanized rubber made of an unvulcanized non-foamable rubber material. A base roll formed by integrally forming a layer around a metal core is disposed concentrically in a molding cavity, and an unvulcanized rubber layer is vulcanized in the molding cavity, thereby unvulcanized rubber. There is also a method in which the layer is a non-foaming elastic layer and the vulcanized rubber tube is a resistance adjusting layer.

  However, the unvulcanized non-foamable rubber material used in such a technique generally contains a large amount of a softening agent such as oil in order to reduce the hardness of the finally obtained charging roll. There was a risk that sufficient adhesion could not be secured at the interface between the non-foaming elastic layer as the vulcanized product and the resistance adjusting layer made of the vulcanized rubber tube.

Japanese Patent Publication No. 6-36901

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is that the resistance adjustment layer made of an ion conductive rubber material is made of a non-foaming rubber material. An object of the present invention is to provide a method of manufacturing a charging roll that can be provided on the outer side of a non-foaming elastic layer thicker and more uniformly than the conventional one.

In the present invention, a non-foaming elastic layer is integrally provided on the outer peripheral surface of the shaft body, and at least a resistance adjusting layer is integrally provided outside the non-foaming elastic layer. (A) a step of preparing a rubber tube made of an ion conductive rubber material, and (b) a disk vulcanization test as defined in JIS-K-6300-2: 2001. torque value at cure curve obtained by: by allowed to vulcanization under between vulcanization temperature and vulcanization time giving 40% to 80% of M _E, the steps of the semi-vulcanized rubber tubes, (c) the Placing the semi-vulcanized rubber tube in a mold cavity of a mold that provides the desired roll shape; and (d) placing the shaft concentrically in the mold cavity of the mold, Shaft body and semi-vulcanized rubber The non-foaming rubber material is provided to give the non-foaming elastic body layer around the shaft body by filling an unvulcanized non-foaming rubber material in a gap formed between the tube and the tube. A step of forming a roll precursor having a semi-vulcanized rubber layer made of the semi-vulcanized rubber tube, which has an unvulcanized rubber layer and provides the resistance adjusting layer on the outside; (e) the roll precursor And vulcanizing the body to complete the vulcanization of the unvulcanized rubber layer and the semi-vulcanized rubber layer, respectively, and forming a non-foaming elastic body layer and a resistance adjusting layer, respectively. The gist of the charging roll manufacturing method is as follows.

  In addition, in such a method for producing a charging roll according to the present invention, in one of its preferred embodiments, a silane coupling agent is blended in either the ion conductive rubber material or the non-foamable rubber material. It has been.

  In another preferred embodiment of the method for producing a charging roll according to the present invention, the step of applying a solution obtained by adding a silane coupling agent to an organic solvent on the inner surface of the semi-vulcanized rubber tube. It has further.

  As described above, in the method of manufacturing the charging roll according to the present invention, before the rubber tube made of the ion conductive rubber material that finally provides the resistance adjusting layer is disposed in the molding cavity of the molding die, It has a great feature in that it is vulcanized under a predetermined vulcanization temperature and heating time to obtain a semi-vulcanized state. Then, an unvulcanized rubber layer made of an unvulcanized non-foamable rubber material that finally gives a non-foamable elastic body layer around a shaft serving as a roll shaft, and the outer half of the unvulcanized rubber layer. When a roll precursor having a semi-vulcanized rubber layer made of a vulcanized rubber tube (semi-vulcanized rubber tube) is formed and the roll precursor is vulcanized, the unvulcanized rubber layer and the semi-vulcanized rubber layer The non-foaming elastic layer and resistance adjusting layer, which are vulcanized rubber layers, have good adhesion even when the semi-vulcanized rubber layer (resistance adjusting layer) is thicker than the conventional one. Since the state can be effectively secured, a charging roll having a thick resistance adjustment layer can be advantageously manufactured as compared with the conventional one.

  In addition, the resistance adjustment layer thus obtained is a vulcanized rubber tube prepared in advance, so that the thickness is uniform compared to the resistance adjustment layer prepared according to the conventional roll coating method. It will be something.

  Furthermore, when the silane coupling agent is blended with either an ion conductive rubber material that provides a resistance adjusting layer or a non-foaming rubber material that provides a non-foaming elastic layer, a resistance adjusting layer finally obtained; The adhesion between the non-foaming elastic layer is further improved. The same effect can be achieved at the latest by the time when the unvulcanized non-foamed rubber material is filled in the gap formed between the shaft and the semi-cured rubber tube in the molding cavity. It can also be enjoyed by applying a solution obtained by adding a silane coupling agent to an organic solvent on the inner surface of the rubber rubber tube.

  The charging roll manufactured in accordance with the present invention has a resistance adjustment layer made of an ion conductive rubber material that is thicker and more uniform than before, so that various characteristics required as a charging roll are not impaired. It exhibits excellent durability.

  Hereinafter, in order to clarify the present invention more specifically, the configuration of the present invention will be described in more detail with reference to the drawings.

  First, FIG. 1 shows a typical example of a charging roll manufactured according to the present invention in a cross section in a direction perpendicular to the axis. In the charging roll 10, a non-foaming elastic body layer 14 made of a non-foaming rubber material is integrally formed on the outer peripheral surface of a metallic conductive shaft body (core metal) 12 made of stainless steel or the like. Further, on the outer peripheral surface of the non-foaming elastic layer 14, from the inner side to the outer side in the roll radial direction, a resistance adjusting layer 16 made of an ion conductive rubber material and a protective layer made of a semiconductive resin material 18 are sequentially stacked with a predetermined thickness. That is, in the charging roll 10, the non-foaming elastic body layer 14, the resistance adjusting layer 16, and the protective layer 18 are respectively predetermined around the shaft body 12 from the inner side to the outer side in the roll radial direction. In this thickness, it has a structure in which the layers are sequentially laminated integrally.

  By the way, when manufacturing the charging roll 10 having such a structure according to the present invention, first, a rubber tube made of an ion conductive rubber material is prepared.

  Examples of the ion conductive rubber material used for producing such a rubber tube include epichlorohydrin rubber and nitrile rubber (NBR), an ion conductive agent, a vulcanizing agent, and an insulating filler as required. In such a ratio, a mixture is used. As the ionic conductive agent used there, any material can be used as long as it is conventionally used in the production of a charging roll. In particular, tetramethylammonium perchlorate or benzyltrimethylammonium chloride. A quaternary ammonium salt such as is advantageously used.

  In addition, production of a rubber tube using such an ion conductive rubber material is performed according to a conventionally known method such as an extrusion molding method or an injection molding method. From the viewpoint of productivity, an extrusion molding method is advantageously employed.

  Furthermore, according to the manufacturing method of the present invention, a charging roll (10) having a resistance adjustment layer (16) thicker than the conventional one can be obtained, but the thickness of the resistance adjustment layer (16) is thick. If the thickness is too large, the durability of the charging roll will be improved, but the hardness of the entire roll will increase, which may adversely affect other roll characteristics. On the other hand, if the thickness is too thin, the durability of the charging roll will be improved. May not be achieved. For this reason, in the present invention, the thickness of the rubber tube that finally provides the resistance adjusting layer (16) is usually set to about 200 μm to 1000 μm.

In the method for producing a charging roll according to the present invention, the rubber tube produced as described above is vulcanized under a predetermined vulcanization temperature and a vulcanization time, and a semi-vulcanized rubber tube and It has a great feature. That is, the rubber tube has a vulcanization temperature and a vulcanization time that gives 40% to 80% of the torque value: M _E in the vulcanization curve determined by the disc vulcanization test specified in JIS-K-6300-2: 2001. Is vulcanized under the condition of a semi-vulcanized rubber tube. Hereinafter, making the rubber tube into a semi-vulcanized rubber tube will be described in detail.

  First, prior to rubber tube vulcanization, an ion conductive rubber material used for the production of such a rubber tube was subjected to a disk vulcanization test (hereinafter simply referred to as “disk vulcanization” defined in JIS-K-6300-2: 2001). The test is also called “test”: X [° C.]. Specifically, the disc vulcanization test is a method in which a test piece made of an ion conductive rubber material heated to a test temperature: X [° C.] is deformed by torsional vibration of the disc, and torque required for such deformation: M [N · m] is continuously recorded as a function of time: t [minute]: M (t). By this disc vulcanization test, a vulcanization curve as shown in FIG. 2 is obtained.

Next, the obtained vulcanization curve is analyzed. Taking the vulcanization curve shown in FIG. 2 as an example, of the measured torque: M, the minimum value is M _L and the maximum value is M _H. Two straight lines that pass through M _L and M _H and are parallel to the time axis (horizontal axis) are drawn, and the distance between the two straight lines is M _E. Therefore, the relationship between M _L , M _H and M _E is M _E = M _H −M _L. The M _E is, in determining the state of cure (degree of vulcanization) of the rubber material, is generally used. For example, according to the description of JIS-K-6300-2: 2001, three straight lines parallel to the time axis are drawn through M _L + 10% M _E , M _L + 50% M _E , M _L + 90% M _E , The intersections of these three straight lines and the vulcanization curve are obtained, and the time required from the start of the test to the respective intersections is defined as t _C (10), t _C (50) t _C (90) (not shown in FIG. 2). ) Where t _C (10) is induction time (vulcanization start point), t _C (50) is 50% vulcanization time (midpoint of vulcanization reaction) t _C (90) is 90% vulcanization time (optimum) Vulcanization point).

In carrying out the present invention, the vulcanization curve is further analyzed following the above-described procedure, and passes through M _L + 40% M _E and M _L + 80% M _E in parallel with the time axis as shown in FIG. Two straight lines are drawn, and the intersections between the two straight lines and the vulcanization curve are obtained, and the time required from the start of the test to each intersection is defined as t _C (40) and t _C (80). These _{t C (40), t C} (80) , according to the concept of the JIS, respectively, t _C (40) is between 40% vulcanization time, t _C (80) becomes between 80% vulcanization. As referred in the present invention, "JIS-K-6300-2: torque value at cure curve obtained by the disc vulcanization test prescribed in 2001: vulcanization time giving 40% M _E" is the above t It corresponds to _C (40), also "JIS-K-6300-2: torque value at cure curve obtained by the disc vulcanization test prescribed in 2001: vulcanization time giving 80% of M _E" is corresponds to the above-described t _C (80), further "JIS-K-6300-2: torque value at cure curve obtained by the disc vulcanization test prescribed in 2001: give 40% to 80% of M _E The “vulcanization temperature” corresponds to the test temperature: X [° C.].

In the present invention, the rubber tube made of the ion conductive rubber material is vulcanized to obtain a semi-vulcanized rubber tube by performing the disk vulcanization test described in detail above and analyzing the vulcanization curve obtained thereby. In this case, one vulcanization condition (vulcanization temperature and vulcanization time. More specifically, X [° C.], t _C (40) ≦ (vulcanization time) ≦ t _C (80).) Is required.

  According to the present invention, when the charging roll is manufactured industrially, the above-described disk vulcanization test is performed a plurality of times at different test temperatures, and each vulcanization curve obtained from each test is analyzed. After confirming a plurality of vulcanization conditions (vulcanization temperature and vulcanization time) that can be employed in the present invention, a more suitable one is appropriately selected from the viewpoint of productivity and the like.

Here, when allowed to vulcanized rubber tubes made of an ion conductive rubber material, the torque value at cure curve obtained by the disc vulcanization test: give less than 40% of the M _E adopted between vulcanization temperature and vulcanization time Then, the vulcanized state of the obtained semi-vulcanized rubber tube is not sufficient, the strength thereof is insufficient, and the following problems may occur. That is, as will be described later, the semi-vulcanized rubber tube (20) is disposed in the molding cavity of the mold and the shaft (12) is concentrically disposed in the molding cavity (see FIG. 3). Thus, when the non-foaming rubber material is injected into the gap between the semi-vulcanized rubber tube (20) and the shaft body (12), the semi-vulcanized rubber tube (20) breaks, resulting in As a result, there is a possibility that a charging roll having the target resistance adjusting layer cannot be obtained. On the other hand, the torque value at cure curve obtained by the disc vulcanization test: If M employing the inter vulcanization temperature and vulcanization time give more than 80% of _E, the effect can not be enjoyed of the present invention, specific In particular, the adhesion between the resistance adjustment layer, which is a vulcanized product of a semi-vulcanized rubber tube, and the non-foaming elastic material layer, which is a vulcanized product of a non-foamable rubber material vulcanization described later, may not be ensured. is there.

  According to the vulcanization temperature and vulcanization time determined as described above, the rubber tube is vulcanized to form a semi-vulcanized rubber tube.

  The obtained semi-vulcanized rubber tube is placed in a cavity of an appropriate mold having a molding cavity that gives the roll shape of the target charging roll 10. In the present invention, as shown in FIG. 3, it is preferably disposed in a so-called pipe-shaped molding cavity having a pipe-shaped mold structure.

  That is, in FIG. 3, the mold 22 includes a pipe portion 24 having a length substantially equal to the axial length of the non-foaming elastic layer 14 (and the resistance adjusting layer 16) in the final shape of the target charging roll 10. The upper and lower cap bodies 26 and 28 are attached to both ends of the pipe portion 24 and close the respective end portions, and as shown in the drawing, a longitudinal rod-like shaft body 12 is formed at the center of the pipe portion 24. In a state where the pipe portion 24 is positioned, both ends of the pipe portion 24 are closed with cap bodies 26 and 28, respectively, so that a cylindrical molding cavity is formed in the pipe portion 24.

  Then, in order to obtain the charging roll 10 having the structure as shown in FIG. 1, the shaft body 12 is arranged at a predetermined position of the mold 22 to form a predetermined molding cavity as shown in FIG. The semi-vulcanized rubber tube 20 for providing the resistance adjusting layer 16 in FIG. 1 is set and disposed on the inner surface of the molded cavity to be provided with the outer peripheral surface of the roll, that is, the inner surface 30 of the pipe portion 24. Thus, a gap 32 is formed between the shaft body 12 and the semi-vulcanized rubber tube 20.

  Thereafter, in this state, an unvulcanized non-foaming rubber material is injected into the gap 32 of the mold 22 by using a casting machine or the like in the conventional manner to fill the gap 23. Thus, a semi-vulcanized rubber having an unvulcanized layer made of a non-foamable rubber material which gives a non-foamable elastic layer 14 around the shaft body 12 and a resistance adjusting layer 16 on the outside thereof A roll precursor having a semi-vulcanized rubber layer made of the tube 20 is formed in the mold 22.

Here, as the non-foaming rubber material injected into the gap 32, conventionally used rubber materials such as SBR, BR, IR, NR, NBR, acrylic rubber, etc., an electronic conductive agent, sulfur In addition, various softeners (liquid polymers, various oils, etc.) for facilitating injection into the mold (casting), if necessary, are blended at a predetermined ratio. What is made is used. Specific examples of the electronic conductive agent used here include carbon black such as FEF, SRF, ketjen black, and acetylene black, metal powder, and conductive metal oxide such as c-TiO ₂ and c-ZnO ₂ . Examples thereof include graphite, carbon fiber, and the like.

  As described above, the vulcanization of the unvulcanized rubber layer and the semi-vulcanized rubber layer of the roll precursor is completed by heating the mold while the roll precursor is formed in the mold 22. Let As a result, a non-foaming elastic body layer 14 is integrally provided on the outer peripheral surface of the shaft body 12, and a vulcanized molded product is formed on the outside of which the resistance adjusting layer 16 is integrally provided. It is.

The obtained vulcanized product is removed from the mold 22 and then the protective layer 18 is formed on the outer peripheral surface thereof, whereby the charging roll 10 having the structure shown in FIG. 1 is manufactured. It is. The protective layer 18 is provided to prevent the toner from adhering to and accumulating on the roll surface. For example, the protective layer 18 is made of a nylon material such as N-methoxymethylated nylon or a fluorine-modified acrylate resin. Is formed so that the volume resistivity is about 1 × 10 ⁸ to 10 ¹³ [Ωcm]. It will be. Further, such a protective layer 18 is formed by a known coating method such as dipping or roll coating, as in the prior art, and its thickness is usually about 3 to 20 μm.

  In the charging roll 10 having such a configuration, since the resistance adjusting layer 16 is provided from a semi-vulcanized rubber tube vulcanized under a predetermined condition, the resistance adjusting layer 16 Even when the thickness of the resistance adjustment 16 is set to be larger than that of the conventional structure, sufficient adhesion is ensured between the elastic layer 14 and the non-foaming elastic layer 14. Therefore, the production method according to the present invention makes it possible to advantageously produce a charging roll having a uniform and thick resistance adjusting layer, which has been difficult to produce so far. The charging roll obtained by this exhibits excellent durability.

  The exemplary embodiments of the present invention have been described in detail above, but these are merely examples, and the present invention is not limited to specific descriptions according to such embodiments. It should be understood that it is not intended to be construed.

  For example, in the above embodiment, a non-foaming elastic body layer and a resistance adjusting layer obtained from these rubber materials by blending a silane coupling agent with either an ion conductive rubber material or a non-foaming rubber material. Adhesiveness is further improved.

  The silane coupling agent used in the present invention is not particularly limited, and specifically includes a mercapto-modified silane coupling agent, an epoxy-modified silane coupling agent, a vinyl-modified silane coupling agent, and a glycidoxy-modified silane coupling. Examples thereof include agents, methacryl-modified silane coupling agents, amino-modified silane coupling agents and the like. These may be used alone or in combination of two or more. In particular, a mercapto-modified silane coupling agent is advantageously used because it does not affect the conductivity of the charging roll. In addition, when there are too few compounding quantities of the silane coupling agent with respect to the said rubber material, the effect (adhesion improvement) of a silane coupling agent is not recognized, conversely, when too large, a resistance adjustment layer or a non-foaming elastic body Since there is a possibility of increasing the hardness of the layer, in the present invention, the rubber component in the ion conductive rubber material or the non-foaming rubber material: 0.01 to 5 parts by weight with respect to 100 parts by weight. In this proportion, the silane coupling agent is blended.

  Even when the silane coupling agent is not blended with the ion conductive rubber material or the like, the rubber tube made of the ion conductive rubber material is vulcanized under a predetermined condition, and the semi-vulcanized rubber tube and After the vulcanization, the semi-vulcanization is performed before the unvulcanized non-foamable rubber material is filled in the gap formed between the shaft body and the semi-vulcanized rubber tube in the molding cavity. The same effect can be enjoyed by applying a solution obtained by adding a silane coupling agent to an organic solvent on the inner surface of the rubber tube. As the organic solvent, methyl ethyl ketone or the like can be used.

  In addition, although not enumerated one by one, the present invention can be carried out in a mode to which various changes, modifications, improvements and the like are added based on the knowledge of those skilled in the art. It should be understood that all of these are within the scope of the present invention without departing from the spirit of the present invention.

  In the following, some typical embodiments of the present invention will be shown to clarify the present invention more specifically. However, the present invention is not restricted by the description of such embodiments. It goes without saying that it is not a thing.

  First, a non-foaming rubber material (non-foaming elastic body layer forming material), an ion conductive rubber material (resistance adjusting layer forming material), and a protective layer forming material were prepared according to the following blending compositions.

-Non-foaming rubber material-(Compounding ratio)
Styrene butadiene rubber 100 parts by weight Carbon black 25 parts by weight Zinc oxide 5 parts by weight Stearic acid 1 part by weight Process oil 130 parts by weight Sulfur 0.3 parts by weight Dibenzothiazole disulfide (vulcanization accelerator) 1.5 parts by weight Tetramethylthiuram mono 0.6 parts by weight of sulfide (vulcanization accelerator)

-Ion conductive rubber material-(Compound ratio)
Epichlorohydrin-ethylene oxide copolymer rubber 100 parts by weight Fine powdered silica 10 parts by weight Tetramethylammonium perchlorate 0.2 parts by weight Stearic acid 1 part by weight Clay 30 parts by weight Lead red 5 parts by weight Ethylenethiourea 1.5 parts by weight

-Protective layer forming material-(Blend ratio)
N-methoxymethylated nylon 100 parts by weight Conductive tin oxide 60 parts by weight Citric acid 1 part by weight

In addition, the disk vulcanization test specified in JIS-K-6300-2: 2001 was performed several times using the ion conductive rubber material according to the above composition, and each vulcanization curve obtained thereby was analyzed. did. And based on the analysis result of this vulcanization curve, the vulcanization conditions (vulcanization temperature and vulcanization time) of rubber tubes in the following Invention Examples 1 to 7, Comparative Example 1, and Comparative Example 2 were determined, respectively. . In the following description of Table 1 and Comparative Example 4 and Comparative Example 5 described below, expressions such as “60% M _E ” are used as the degree of vulcanization of the semi-vulcanized rubber tube. For clarifying the vulcanization state (vulcanization degree) of a semi-vulcanized rubber tube, specifically, in the present invention example or the comparative example, vulcanization conditions for vulcanizing the rubber tube 1) The vulcanization temperature is X ′ [° C.], and 2) the vulcanization time is the vulcanization curve obtained in the disk vulcanization test previously performed at the temperature: X ′ [° C.]. This means that the time [t _C (60)] until the measured value of torque reaches [M _L + 60% M _E ] is adopted.

  The various characteristics of the charging roll obtained below were measured or evaluated as follows.

-Average thickness of resistance adjustment layer-
About the obtained charging roll, the roll axial direction center part of the roll part (the part in which the non-foaming elastic body layer, the resistance adjusting layer and the protective layer are laminated and formed) is cut, and in the roll circumferential direction on the cut surface Four portions separated at 90 ° intervals were enlarged, and the thicknesses of the resistance adjusting layers at these four locations were measured. The four measured values obtained were averaged to obtain the average thickness of the resistance adjustment layer.

-Measurement of Asker C hardness-
Using a spring-type hardness tester (rubber / plastic hardness meter / Asker C type, manufactured by Kobunshi Keiki Co., Ltd.), the central part in the axial direction of the charging roll held horizontally with both ends supported by a V block The tip of the push needle of the spring type hardness tester is brought into contact with the surface of the test piece, and after further pressurizing the tester vertically with a load of 1000 g (total load including the tester), the scale is immediately adjusted. The hardness of the roll was measured by reading.

-Evaluation of initial image and durability performance-
It is obtained by assembling the charging roll into a drum cartridge of a commercially available printer: DocuPrint C3530 (Fuji Xerox Co., Ltd.) and printing a magenta halftone image in a 15 ° C x 10% RH environment. The observed image was visually observed. The initial image was evaluated as “◯” when there was no abnormality in the image and “X” when abnormality was recognized.

  For the charging roll whose initial image was evaluated as “◯”, a pattern image of A4 size with a print density of 5% was continuously printed until an abnormality occurred in the obtained image. The presence or absence of abnormality in the obtained image was confirmed by printing a magenta halftone image every 5,000 sheets. When the life of the drum cartridge was exhausted earlier than the life of the charging roll, continuous printing was performed by changing the charging roll to a new drum cartridge each time. If the image abnormality occurs after continuous printing exceeding 200,000 sheets in total, “○” is indicated. If the image abnormality occurs during continuous printing of 100,000 to 200,000 sheets, “△” is indicated. Performance was evaluated.

Invention Example 1 to Invention Example 7
First, a plurality of rubber tubes having different thicknesses were prepared by extruding an ion conductive rubber material. In the extrusion molding, the target thickness (set thickness) of the rubber tube was set to any one of 200 μm, 500 μm, and 1000 μm. Next, the obtained rubber tube was vulcanized under a predetermined vulcanization temperature and vulcanization time to obtain a semi-vulcanized rubber tube.

  Next, a pipe mold (24) as shown in FIG. 3 is used as a mold, and a metal shaft body (12) having an outer diameter: 9 mm × length: 331 mm is disposed in the molding cavity, while a roll is provided. Any of the semi-vulcanized rubber tubes obtained above was inserted and set on the inner surface of the pipe (24) providing the outer peripheral surface.

  Then, in such a state that the shaft body (12) and the semi-vulcanized rubber tube (20) are set as described above, in the gap between the shaft body (12) and the semi-vulcanized rubber tube (20), The prepared non-foaming rubber material was injected, and the entire mold (20) was heated for a predetermined time to produce a vulcanized molded product. Then, after cooling, the obtained vulcanized product is taken out from the pipe mold (24), and the protective layer (18) as the outermost layer is formed on the outer peripheral surface of the resistance adjusting layer (16). Using the forming material, coating was performed by a roll coating method to obtain a target charging roll having the structure shown in FIG. 1 (Invention Examples 1 to 7). The obtained charging roll had a product diameter: φ14 mm, a non-foaming elastic layer thickness: 2 mm, a resistance adjustment layer thickness: as shown in Table 1, and a protective layer thickness: 10 μm.

  About the obtained seven types of charging rolls, the thickness of the resistance adjusting layer and the Asker C hardness were measured, the initial image and the durability performance were evaluated. The results are also shown in Table 1 below.

Comparative Examples 1-3
A pipe having a smaller inner diameter than that of the above-described pipe mold was prepared, and a shaft body was concentrically disposed in the molding cavity. In that state, the non-foaming rubber material prepared above is injected into the molding cavity, and then the entire mold is heated for a predetermined time, whereby a non-foaming elastic layer is formed on the outer peripheral surface of the shaft body. A vulcanized molded product in which was formed integrally was prepared. After demolding, the ionic conductive rubber material described above is melted in MEK for the resulting vulcanized molded product, and a liquid material is prepared by stirring, and coating is performed using this liquid material by a roll coating method. Then, the resulting coating liquid layer was dried to produce a resistance adjusting layer. This coating was carried out by setting the target thickness (set thickness) of the coating liquid layer to 200 μm in Comparative Example 1, 500 μm in Comparative Example 2, and 1000 μm in Comparative Example 3. When the formed resistance adjusting layer was visually observed after the coating, it was found that the thickness of the coating liquid layer was uneven. Further, a protective layer was formed according to the same method as in Examples 1 to 7 of the present invention to obtain three types of charging rolls (Comparative Examples 1 to 3).

  About the obtained three types of charging rolls (Comparative Examples 1 to 3), the thickness of the resistance adjusting layer and Asker C hardness were measured, and the results are shown in Table 1 below. Further, when these rolls were used to evaluate the initial image, density unevenness of the image, which seems to be caused by the thickness unevenness of the resistance adjustment layer, was recognized for all the charging rolls. For this reason, the durability performance of these three types of charging rolls was not evaluated.

  As is apparent from the results of Table 1, the charging rolls produced according to the present invention (Invention Examples 1 to 7) have good adhesion between the non-foaming elastic layer and the resistance adjusting layer. In other words, it was recognized that it can withstand continuous printing of 100,000 sheets or more in total. In particular, it was recognized that the resistance adjustment layer having a thickness of about 200 μm to 1000 μm (Invention Example 1 to Invention Example 5) exhibits excellent durability performance.

Comparative Example 4
An attempt was made to produce a charging roll according to the same method as in the present invention except that a semi-vulcanized rubber tube having a low vulcanization degree (30% M _E ) was used. However, while injecting the non-foaming rubber material, the semi-vulcanized rubber tube was broken and the intended charging roll could not be obtained.

An attempt was made to produce a charging roll according to the same method as in the present invention except that a semi-vulcanized rubber tube having a high degree of vulcanization (90% M _E ) was used. However, after vulcanization, when the vulcanized molded product obtained by taking out from the pipe mold was confirmed, the adhesion between the non-foaming elastic layer and the resistance adjusting layer was not sufficient, and it could not be used as a charging roll It was confirmed that

It is a cross-sectional explanatory drawing which shows an example of the charging roll manufactured according to this invention. It is a graph which shows an example of the vulcanization curve calculated | required by the disk vulcanization | cure test prescribed | regulated to JIS-K-6300-2: 2001. It is longitudinal cross-sectional explanatory drawing which shows an example of the metal mold | die used in this invention, Comprising: The state which has arrange | positioned the semi-vulcanized rubber tube to the inner surface of the side which gives the roll outer peripheral surface in the molding cavity is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Charging roll 12 Shaft body 14 Non-foaming elastic body layer 16 Resistance adjustment layer 18 Protective layer 20 Semi-vulcanized rubber tube 22 Mold 24 Pipe part 26, 28 Cap body 30 Inner surface 32 Gap

Claims (3)

A charging roll manufacturing method in which a non-foaming elastic layer is integrally provided on the outer peripheral surface of a shaft body, and at least a resistance adjusting layer is integrally provided outside the non-foaming elastic layer. ,
A step of preparing a rubber tube made of an ion conductive rubber material;
The rubber tube, JIS-K-6300-2: torque value at cure curve obtained by the disc vulcanization test prescribed in 2001: M 40% or between giving 80% vulcanization temperature and vulcanization time _E By vulcanizing underneath, a process of making a semi-vulcanized rubber tube,
Placing the semi-vulcanized rubber tube in a molding cavity of a mold that provides the desired roll shape;
The shaft body is concentrically disposed in a molding cavity of the mold, while an unvulcanized non-foaming rubber material is placed in a gap formed between the shaft body and the semi-vulcanized rubber tube. The unvulcanized rubber layer made of the non-foamable rubber material is provided around the shaft body to provide the non-foamable elastic body layer, and the resistance adjusting layer is provided on the outside thereof. Forming a roll precursor having a semi-vulcanized rubber layer comprising a semi-vulcanized rubber tube;
Vulcanizing the roll precursor to complete vulcanization of the unvulcanized rubber layer and the semi-vulcanized rubber layer, respectively, and forming a non-foaming elastic layer and a resistance adjusting layer, respectively;
A method for producing a charging roll, comprising:   The method for producing a charging roll according to claim 1, wherein a silane coupling agent is blended in either the ion conductive rubber material or the non-foamable rubber material. The manufacturing method of the charging roll of Claim 1 which further has the process of apply | coating the solution formed by adding a silane coupling agent to an organic solvent to the inner surface of the said semi-vulcanized rubber tube.

Images