JP5300316B2 - Method for producing elastic roller - Google Patents

Description

  The present invention relates to a method for manufacturing an elastic roller used in an electrophotographic image forming apparatus such as a copying machine, a page printer, and a facsimile machine.

  As a cored bar of an elastic roller such as a charging roller used in an electrophotographic image forming apparatus, a form using a cored bar 101 (hereinafter also referred to as “stepped cored bar”) shown in FIG. 1 is known (Patent Document). 1 (see FIG. 3). In the metal core 101, a radius R2 of a cylindrical portion (referred to as a second cylindrical portion) 103 located at both ends is smaller than a radius R1 of a cylindrical portion (referred to as a first cylindrical portion) 102 located at the center. An elastic roller using such a stepped mandrel has a core even when a pressing force is applied only to both ends of the elastic roller when the elastic roller is brought into contact with the contacted member. It has the advantage that gold is difficult to bend. Due to this advantage, for example, when the elastic roller is used as a charging roller, an effect that charging unevenness in the width direction of the member to be charged can be suppressed can be obtained (Patent Document 1, paragraph numbers [0017] to [0018], [0018] 0027]).

By the way, a method using a crosshead is known as one of methods for producing an elastic roller in which the outer peripheral surface of a core metal is covered with an elastic layer (Patent Document 2). However, in an elastic roller manufactured by a method using a normal crosshead, the end of the elastic layer may be easily peeled off from the cored bar. That is, in the method using a normal crosshead, first, the elastic layer forming material is supplied around the cored bar in a heated state. Thereafter, the layer made of a material for forming an elastic layer covering the periphery of the core metal (hereinafter also referred to as “material layer”) starts to shrink as it is cooled. At this time, the side of the material layer not facing the cored bar tends to contract more than the side facing the cored bar. Therefore, as shown in FIG. 2, the rubber composition layer 202 easily peels off at the end of the cored bar 201. In order to deal with such a problem, a method is known in which a material layer at both ends of a core metal discharged from a cross head is sandwiched between end pressing jigs and the core metal is taken up (Patent Documents 2 and 3).
JP-A-9-101648 JP 2007-15137 A JP 2006-123256 A

  According to the method described in Patent Document 2 or 3, peeling at the end of the material layer accompanying shrinkage can be effectively suppressed. However, the portion sandwiched between the end pressing jigs of the material layer has a diameter different from that of the first cylindrical portion, and cannot be used as an elastic layer of an electrophotographic elastic roller as it is. Therefore, the sandwiched portion is usually cut and removed.

  Here, when this method is applied to the above-described stepped core bar, both end portions in the axial direction of the first cylindrical portion having a large diameter have a form in which no elastic layer exists. That is, the ratio of the length of the elastic layer in the axial direction to the total length of the stepped mandrel becomes a small elastic roller. Such an elastic roller is disadvantageous for further miniaturization of the electrophotographic image forming apparatus.

  Accordingly, an object of the present invention is to provide an electrophotographic image forming apparatus in which the ratio of the axial length of the elastic layer to the total length of the stepped mandrel is high and peeling is unlikely to occur at the end of the elastic layer. An object of the present invention is to provide a method for manufacturing an elastic roller effective for miniaturization.

The elastic roller manufacturing method according to the present invention includes (1) a first cylindrical portion having a radius R1 and a radius R1 that is continuous with both ends of the first cylindrical portion and is coaxial with the first cylindrical portion. A core metal having a second cylindrical portion having a small radius R2 is passed through the cross head, and the rubber composition is pushed out around the core metal over the entire length of the core metal, thereby surrounding the first cylindrical portion. Coating a surface with a layer of the rubber composition and surrounding the second cylindrical portion with the layer of the rubber composition;
(2) The rubber composition layer surrounding the second cylindrical portion of the mandrel after passing through the crosshead is positioned outside the rubber composition layer at a position away from the first cylindrical portion. A method of manufacturing an elastic roller having a step of gripping with a gripping member and bringing a layer of the rubber composition into contact with a peripheral surface of the second cylindrical portion,
In the step (2), the rubber composition layer surrounds the second cylindrical portion on the side closer to the first cylindrical portion than the position where the layer of the rubber composition is in contact with the peripheral surface of the second cylindrical portion. Restricting the outer diameter of the rubber composition layer to be larger than the outer diameter of the rubber composition layer covering the peripheral surface of the first cylindrical portion as the rubber composition is gripped by the gripping member. However, it is characterized by being performed.

  According to the present invention, an elastic roller is obtained in which an elastic layer is formed in the entire width direction of the first cylindrical portion of the stepped mandrel, and the elastic layer is hardly peeled off at both end portions of the first cylindrical portion. be able to. That is, the ratio of the width of the elastic layer to the length of the shaft core can be increased. Therefore, it is possible to obtain an elastic roller that is advantageous for downsizing the electrophotographic image forming apparatus.

The elastic roller manufacturing method according to the present invention includes (1) a first cylindrical portion having a radius R1 and a radius R1 that is continuous with both ends of the first cylindrical portion and is coaxial with the first cylindrical portion. A core metal having a second cylindrical portion having a small radius R2 is passed through the cross head, and the rubber composition is pushed out around the core metal over the entire length of the core metal, thereby surrounding the first cylindrical portion. Coating a surface with a layer of the rubber composition and surrounding the second cylindrical portion with the layer of the rubber composition;
(2) The rubber composition layer surrounding the second cylindrical portion of the mandrel after passing through the crosshead is positioned outside the rubber composition layer at a position away from the first cylindrical portion. A method of manufacturing an elastic roller having a step of gripping with a gripping member and bringing a layer of the rubber composition into contact with a peripheral surface of the second cylindrical portion,
In the step (2), the rubber composition layer surrounds the second cylindrical portion on the side closer to the first cylindrical portion than the position where the layer of the rubber composition is in contact with the peripheral surface of the second cylindrical portion. Restricting the outer diameter of the rubber composition layer to be larger than the outer diameter of the rubber composition layer covering the peripheral surface of the first cylindrical portion as the rubber composition is gripped by the gripping member. While doing.

  Hereinafter, the manufacturing method of the elastic roller concerning this invention is demonstrated in detail.

(Stepped cored bar)
The stepped core bar used in the present invention is shown in FIG. That is, it has the 1st cylindrical part 102 and the 2nd cylindrical part 103 connected to the both ends, and the radius R2 of the 2nd cylindrical part 103 is smaller than the radius R1 of the 1st cylindrical part 102. FIG. In addition, the second cylindrical portion 103 and the first cylindrical portion 102 are formed coaxially (the same central axis).

  As a constituent material of the stepped core metal 101, for example, a metal such as iron, copper, stainless steel, aluminum, or nickel, or an alloy thereof (for example, aluminum) is used from the viewpoint of suppressing deflection when pressed against the contacted member. Alloy) or the like is preferably used. The radius R1 of the first cylindrical portion 102 is not particularly limited. However, in the case of an elastic roller used in an electrophotographic image forming apparatus, the radius R1 has a strength for suppressing the occurrence of deflection due to the pressing force applied to the elastic roller. Therefore, the thickness is preferably 3 to 6 mm. Similarly, the radius R2 of the second cylindrical portion 103 is not particularly limited. However, the second cylindrical portion 103 is a contact portion with a member that supports the elastic roller in the electrophotographic image forming apparatus. In order to reduce the size of the supporting member, it is preferable to make it as small as possible. On the other hand, it is preferable that the second cylindrical portion 103 has sufficient mechanical strength because it also serves as a portion to which a pressing force is applied to the contacted member. Therefore, the radius R2 of the second cylindrical portion 103 is preferably 2 to 4 mm. The first cylindrical portion 102 and the second cylindrical portion 103 may be hollow or solid as long as necessary strength is maintained.

  An outline of the elastic roller according to the present invention is shown in FIG. In the elastic roller according to the present invention, for example, as shown in FIG. 3, an elastic layer 301 is formed over the entire length of the first cylindrical portion 102 of a stepped core metal.

(Process (1); extrusion process)
In the present invention, first, a stepped core bar is passed through a cross head, and the rubber composition is extruded around the core bar over the entire length of the core bar, whereby the peripheral surface of the first cylindrical portion is rubber composition. And an extrusion step of surrounding the second cylindrical portion with a layer of the rubber composition.

  In the extrusion step, a rubber composition as a raw material for the elastic layer is extruded around the stepped core metal using a crosshead, and a layer of the rubber composition is formed around the stepped core metal. The rubber composition is extruded into a tube shape. FIG. 4 is a schematic explanatory view of a method for producing an elastic roller according to the present invention using a stepped mandrel. In FIG. 4, 401 is a layer of a rubber composition, 402 is a crosshead, 403 is an extruder that kneads an unvulcanized rubber composition and supplies it to the crosshead, and 404 is a coating discharged from the crosshead. A support member that receives the cored bar. Then, a rubber composition is extruded into a tube shape from a die (not shown) having a predetermined diameter inside the crosshead 402 over the entire length of the stepped core metal 101, and a layer of the rubber composition is formed around the stepped core metal 101. . Thereby, as shown in the schematic cross-sectional view of FIG. 4, the outer peripheral surface of the first cylindrical portion 102 of the stepped core metal 101 is covered with the layer 401 of the rubber composition. The second cylindrical portion 103 is surrounded by the rubber composition layer 401. For details of the crosshead, for example, Patent Documents 2 and 3 can be referred to.

  In addition, it is preferable that the cored bar insertion unit of the crosshead 402 is provided with a cored bar supply unit 407 in the upper part of the crosshead so that the stepped cored bar 101 can be continuously supplied.

  The first cylindrical portion 102 may be subjected to a primer treatment in order to improve the adhesion of the rubber composition. In the second cylindrical portion, the rubber elastic layer around the second cylindrical portion is removed after the rubber composition layer is made into a rubber elastic layer in a later step. A mold release treatment may be performed.

(Rubber composition)
Examples of the polymer mainly constituting the rubber composition include the following. Natural rubber, butadiene rubber, styrene butadiene rubber (SBR), nitrile rubber, ethylene propylene rubber (EPDM), chloroprene rubber (CR), nitrile butadiene rubber (NBR), epichlorohydrin rubber, butyl rubber, silicone rubber, urethane rubber, fluorine rubber or chlorine Rubber etc.

  Various known additives can be added to the rubber composition. Examples thereof include a conductive material for imparting conductivity to the rubber elastic layer, a vulcanizing agent for promoting vulcanization of the rubber composition, and an organic or inorganic filler for improving mechanical properties.

Examples of the conductive material include the following. Carbons such as carbon black and graphite (conductive carbon, etc.), metal oxides (titanium oxide, tin oxide, zinc oxide, etc.), solid solutions of SnO ₂ and Sb ₂ O ₃ , solid solutions of ZnO and Al ₂ O ₃ , etc. Double oxide, metal powder such as Cu or Ag, conductive fiber or ionic conductive agent. It is preferable that content of electroconductive powder shall be 5-200 mass parts with respect to 100 mass parts of said polymers.

  As the vulcanizing agent, a known vulcanization accelerator can be used. Specific examples include sulfur, metal oxide, or organic oxide. Examples of the inorganic filler include, but are not limited to, carbon black, talc, clay, calcium carbonate, and the like. In addition, process oil or the like may be added as appropriate.

  The unvulcanized rubber composition is extruded in a tube shape onto a core metal by a cross head to form a layer of the rubber composition. The layer thickness of the rubber composition is generally 0.5 to 5 mm. The present invention is particularly effective at 1.5 to 5 mm.

  In addition, the effect of the present invention is lost even if a layer is provided on the outer periphery or surface treatment is performed for resistance adjustment or surface property adjustment after extrusion molding, for example, forming a conductive roller. Is not something

(Process (2))
In the step (2), the rubber composition layer surrounding the second cylindrical portion is gripped using a gripping member, and the rubber composition layer is brought into contact with the peripheral surface of the second cylindrical portion. Further, at that time, the rubber composition surrounding the second cylindrical portion on the side closer to the first cylindrical portion than the position where the gripping member makes the rubber composition layer contact the peripheral surface of the second cylindrical portion. The regulating member restricts the layer from spreading outward as the rubber composition is gripped by the gripping member. Hereinafter, the step (2) will be described in detail.

  In the extruding step, for example, a stepped core bar having a rubber composition formed thereon as shown in FIG. 5 is obtained. In this state, for the reasons described above, shrinkage starts by cooling the rubber composition immediately after discharge, deformation of the layer of the rubber composition occurs, and finally the end of the first cylindrical portion where the rubber elastic layer should be left. Peeling occurs. In order to prevent this peeling, it is not preferable to hold the first cylindrical portion 102 because the ratio of the rubber elastic layer is reduced. Thus, in the present invention, the rubber composition surrounding the second cylindrical portion is brought into contact with the second cylindrical portion using a gripping member, thereby suppressing the separation in the first cylindrical portion. That is, by gripping the rubber composition in the second cylindrical portion and bringing it into contact with the second cylindrical portion, the layer of the rubber composition at the end of the first cylindrical portion is subjected to stress toward the axial center of the cored bar. As a result, it will not peel off.

  By the way, as mentioned above, when the rubber composition is brought into contact with the peripheral surface at a predetermined position of the second cylindrical portion using the gripping member, the region closer to the first cylindrical portion than the position (FIG. 6 (see 601), the shape of the rubber composition layer may be deformed. That is, the rubber composition immediately after extrusion is tube-shaped, but, for example, a rubber composition in which the diameter (D2) 602 of the rubber composition layer surrounding the second cylindrical portion covers the peripheral surface of the first cylindrical portion. It is conceivable that the diameter of the layer (D1) is larger than 603 (FIG. 6). This is considered to be due to the deformation of the layer of the rubber composition due to the escape of the unvulcanized rubber composition pushed by the gripping member 605. And generation | occurrence | production of such an area | region may induce peeling | exfoliation 604 of the rubber composition in the edge part of a 1st cylindrical part, as shown to 601 of FIG.

  Accordingly, in the present invention, at least the layer 401 of the rubber composition is restricted from being expanded outside the position at the time of extrusion in the second cylindrical portion 103 in the vicinity of the first cylindrical portion end portion 102. More specifically, as shown in FIG. 7, a restriction member 706 is used to regulate the second cylindrical portion 103 on the side closer to the first cylindrical portion 102 than the contact position of the vulcanized rubber composition layer 401. I do. The regulation is such that the diameter of the rubber composition surrounding the second cylindrical portion 103 covers the peripheral surface of the first cylindrical portion as the rubber composition layer is gripped by the gripping member 705. It becomes larger than the diameter of the layer of an object by using the control member 706 (FIG. 7). Thereby, deformation of the rubber composition layer at the end of the first cylindrical portion 102 can be prevented, and peeling of the rubber composition layer at the end of the first cylindrical portion can be more effectively suppressed. Further, the position regulated by the regulating member 706 is preferably around the second cylindrical portion 103 and in the vicinity of the end of the first cylindrical portion, and around the second cylindrical portion 103 and the first cylindrical portion 103. It is more preferable that the position be as close as possible to the cylindrical portion 102.

  The regulation in the step (2) will be described more specifically with reference to FIG. FIG. 8 shows a state in which the rubber composition is regulated using only the regulating member 706 without using the gripping member for easy understanding of the regulation.

It may be regulated by a regulating member 706 having the same inner diameter as the outer diameter D1 of the rubber composition layer 401 as shown in FIG. 8A or a smaller inner diameter as shown in FIG. 8B. Preferably, as shown in FIG.8 (b), it energizes toward the 2nd cylindrical part side. When energizing, the outer diameter D3 of the rubber composition layer in the region energized by the regulating member 706 becomes smaller than the outer diameter D1 of the rubber composition layer covering the first cylindrical portion 102. At this time, at the end of the first cylindrical portion 102, the rubber composition layer 401 is subjected to stress toward the axis center of the core metal, and is more difficult to peel off. However, excessive biasing may promote plastic deformation of the rubber composition layer 401 and may cause delamination as shown in FIG. In the present invention, it is preferable that the rubber composition layer 401 is energized within a range where it does not come into contact with the second cylindrical portion 103. In consideration of the above, the outer diameter D3 of the rubber composition layer in the region urged by the regulating member 501 is:
D1>D3> 2 (R2 + T)
(Here, T is the layer thickness of the rubber composition, and D1 is the outer diameter of the rubber composition layer around the first cylindrical portion 101 as described above, and is represented by D1 = 2 (R1 + T). Is the radius of the first cylindrical portion, and R2 is the radius of the second cylindrical portion.)
It is preferable to satisfy the relationship. More preferably, it is desirable to energize D3 in a range where D3> 2 (R1 + 0.8T).

  As shown in FIG. 4, it is preferable that the region where such regulation is performed be performed on both of the second cylindrical portions provided at both ends of the stepped core metal. In addition, the position of the region where the restriction is performed is the second cylindrical portion in the vicinity of the end portion of the first cylindrical portion, specifically, the first cylindrical portion from the axial central portion of the second cylindrical portion 103. This is the cylindrical portion 102 side. This is preferably performed in a region closer to the first cylindrical portion 102.

<Gripping member>
As long as the gripping member is a member that can grip the rubber composition layer from the outside and make contact with the second cylindrical portion, a conventionally known device or mechanism can be used and is particularly limited. It is not a thing.

  The shape of the contact surface of the gripping member to the rubber composition is preferably a shape that follows the shape of the cylindrical cored bar. For example, an arc shape and a polygonal shape are mentioned. By being circular arc shape or polygonal shape, it is possible to suppress a deformation | transformation of an unvulcanized rubber composition. More preferably, the surface in contact with the unvulcanized rubber composition as shown in FIG. 9 has an arc shape. Moreover, it is preferable that the grip member has a configuration in which a plurality of components whose circular apertures are circular when closed are moved toward the axis center of the cored bar. For example, as shown in FIG. 9, there is one that is composed of two parts 901 a and 901 b and moves so as to sandwich a metal core laminated with a rubber composition. Moreover, it is comprised from four components 1001a-10001d as shown in FIG. 10, and each component moves toward the axial center of the metal core which laminated | stacked the rubber composition, and the thing closed is mentioned. Note that tearing of the rubber composition may occur during gripping.

  More specifically, as shown in FIG. 11, the pair of gripping members 901a and 901b has a circular arc surface 902 that is in contact with the unvulcanized rubber composition at the portion facing the second cylindrical portion. And flank surfaces 903 on both sides. In this way, the gripping members 901a and 901b can wrap the second cylindrical portion 103 of the stepped core metal while sandwiching the rubber composition layer 401, and at the same time, allow the rubber composition to escape to the flank 903 ( (See FIG. 9B). By doing in this way, the escape amount of the rubber composition between a holding member and the 1st cylindrical part can be decreased. Moreover, it is comprised from four components 1001a-10001d as shown in FIG. 12, and each component moves toward the axial center of the core metal which laminated | stacked the rubber composition, and closes. Also in this case, it is preferable to form a relief surface on the surface of the adjacent member.

  The gripping member may be a part of the support member or may be separate and independent. Since gripping is preferably performed before peeling occurs, a gripping member is provided in a part of the extrusion device, and grips from the outside of the rubber composition at the end of the second cylindrical portion in conjunction with the extrusion of the rubber composition. It is preferable to do.

  Moreover, as shown in FIG.13 and FIG.14, it can also be set as the structure which integrated the function of the holding member and the control member.

<Regulating member>
The regulating member is not particularly limited as long as it can regulate the deformation of the rubber composition layer around the second cylindrical portion. It is preferable that the rubber composition layer around the second cylindrical portion can be urged from outside to inside. For example, at least two members having an R shape on the inner surface where D3 is smaller than the outer diameter D1 of the rubber composition layer are sandwiched from the outer side of the rubber composition layer. Further, in order to reduce the amount of plastic deformation of the rubber composition layer, the contact surface of the regulating member with the rubber composition layer is less than the planar shape as shown in FIG. It is good also as circular arc shape as shown in (b), the shape which chamfered the rectangular corner | angular part, or polygonal shape. When energizing is not performed as shown in FIG. 8 (a), a member having the same outer diameter D1 as the inner peripheral surface of the rubber composition layer may be used.

In the present invention, along with the above-described regulation, the rubber component layer is held in contact with the second cylindrical portion by using the holding member on the end side of the axial center of the second cylindrical portion. For example, as shown in FIG. 7, the outer end portion of the second cylindrical portion 103 is gripped by the gripping member 705, and is restricted on the first cylindrical portion 102 side of the second cylindrical portion 103. By doing so, even if the rubber composition pressed and escaped by the gripping member moves to the regulating member side and the rubber composition layer 401 spreads between the gripping member 705 and the regulating member 706, the first The rubber composition layer 401 can be prevented from peeling off at the end of the cylindrical portion 102. The pushing amount of the gripping member is a line segment parallel to the moving direction of the gripping member passing through the axis of the cored bar in the gripping portion after gripping shown in FIG. 7 and connecting the contact portion between the rubber composition and the gripping member 705. Length D4 is 2 (R2 + T)>D4> 2 (R2 + 0.25T)
It is preferable that (Here, T is the layer thickness of the rubber composition, D4 is the radius of the second cylindrical portion as described above, and R2 is the radius of the second cylindrical portion.)
As a preferable form of the regulating member, the configuration examples shown in FIGS. 9 and 10 can be cited as in the case of the gripping member. Specifically, the restricting member in the configuration example of FIG. 9 includes two parts, and the parts are installed so as to be openable and closable. The restricting member in the configuration example of FIG. 10 includes four parts, and the parts are installed so as to be openable and closable.

  Although not particularly limited, it is preferable to grip the rubber composition after first closing the regulating member to regulate the deformation of the rubber composition layer.

  Moreover, as shown in FIG.13 and FIG.14, it can also be set as the structure which integrated the function of the holding member and the control member.

(Vulcanization process)
The stepped core bar having the rubber composition obtained in the step (2) is heated by means of a hot stove, a vulcanizing can, a hot platen, far / near infrared rays, induction heating, etc. Vulcanized. Although the heating temperature varies depending on the rubber composition, the heating time is 130 ° C. to 250 ° C., and the heating time is 5 minutes to 240 minutes, preferably 140 ° C. to 220 ° C., for 10 minutes to 60 minutes. Thereafter, secondary vulcanization may be performed as necessary.

(Cutting process)
Finally, the rubber elastic layer is cut at the boundary between the first cylindrical portion and the second cylindrical portion, and the rubber elastic layer around the second cylindrical portion is removed. Thereby, as shown in FIG. 3, the elastic roller which has the rubber elastic layer 301 over the full length of the 1st cylindrical part 102 is obtained. The rubber elastic layer may be cut from the boundary between the first cylindrical portion and the second cylindrical portion to the first cylindrical portion side or the second cylindrical portion side. Further, the rubber elastic layer 301 of the elastic roller can be further cut into an elastic roller having a predetermined size. For example, by changing the cutting amount between the central portion and the end portion of the rubber elastic layer 301, the elasticity of the crown shape A roller is obtained. Further, as described above, a surface layer may be formed on the surface of the rubber elastic layer 301 or a surface treatment may be performed.

(Embodiment 1)
Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. In particular, the apparatus used in the present embodiment is an example having a configuration for suitably carrying out the present invention, and does not limit the present invention.

<Process (1); extrusion process>
FIG. 4 is a schematic explanatory view of a method for producing an elastic roller according to the present invention using a stepped mandrel. In FIG. 4, 402 is a cross head, 404 is a support member, 405 is a holding member, and 406 is a regulating member. The crosshead 402 is supplied with a stepped core metal 101 and an unvulcanized rubber composition as an elastic layer forming material from an unillustrated extruder. Then, the rubber composition 401 is extruded around the stepped core metal by the cross head 402 over the entire length of the stepped core metal 101. As a result, as shown in the schematic cross-sectional view of FIG. 5, the peripheral surface of the first cylindrical portion 102 is covered with the rubber composition 401, and the second cylindrical portion 103 is surrounded by the rubber composition 401. It becomes.

  In addition, it is preferable that the cored bar insertion unit of the crosshead 402 is provided with a cored bar supply unit 407 above the crosshead so that the stepped cored bar can be continuously supplied.

<Step (2)>
A stepped core bar that passes through the cross head 402 and has an unvulcanized rubber composition 401 formed around it is supported by a support member 404 at one end surface. The apparatus in the present embodiment is configured to feed the stepped core bar vertically downward, and the support member 404 is configured to be movable vertically downward under the force of the stepped core metal discharged from the crosshead. . After the stepped core metal supported by the support member 404 is lowered to a predetermined position, the unvulcanized rubber composition is cut.

  Here, as shown in FIG. 7, the stepped core after being discharged from the cross head has the rubber composition layer 401 surrounding the second cylindrical portion 103 and the gripping member 705 from the outside. And the rubber composition is brought into contact with the second cylindrical portion. The gripping by the gripping member is performed at at least one location in the second cylindrical portion away from the first cylindrical portion. Thereby, the layer 401 of the rubber composition can be brought into contact with the peripheral surface of the second cylindrical portion 103. As a result, it is possible to suppress the peeling of the rubber composition due to the difference in the degree of shrinkage between the rubber composition on the core metal side and the outer peripheral side accompanying the cooling of the rubber composition layer. The position where the rubber composition layer is gripped by the gripping member is preferably as far as possible from the first cylindrical portion. Thereby, the deformation that may occur in the rubber composition layer accompanying the gripping can be prevented from propagating to the rubber composition that covers the first cylindrical portion.

  Specific examples of the present invention will be described below. The present invention is not limited to the following examples. In particular, the apparatus and members used in the present embodiment are examples that have a configuration for suitably carrying out the present invention, and do not limit the present invention.

Example 1
The following materials were prepared as materials for the charging roller.

(Rubber composition)
The following materials were mixed with an open roll to prepare an unvulcanized rubber composition.
-Terpolymer of epichlorohydrin 40 mol%-ethylene oxide 56 mol%-allyl glycidyl ether 4 mol%: 100 parts by mass
-Zinc oxide (Zinc oxide two types; manufactured by Shodo Chemical Co., Ltd.): 5 parts by mass
-Tetrabutylammonium perchlorate as an ionic conductive agent: 1 part by mass,
Calcium carbonate (trade name: Silver W; manufactured by Shiroishi Calcium Co.): 55 parts by mass
Carbon black (trade name: Seast SO; manufactured by Tokai Carbon Co., Ltd.): 8 parts by mass
・ Stearic acid as a processing aid: 2 parts by mass
-Adipic acid ester as a plasticizer (trade name: Polysizer W305ELS; manufactured by Nippon Ink Chemical Co., Ltd.): 10 parts by mass
・ Sulfur as a vulcanizing agent: 0.5 parts by mass
-Dipentamethylene thiuram tetrasulfide (trade name: Noxeller TRA; manufactured by Ouchi Shinsei Chemical Co., Ltd.) as a crosslinking aid: 2 parts by mass.

(Stepped cored bar)
Next, a stepped core bar having a total length of 358 mm was prepared. The stepped mandrel has a second cylindrical portion (φ6 mm, length 15 mm) and a first cylindrical portion (φ8 mm, length 328 mm). A hot melt type conductive adhesive was applied to the core bar in a region excluding 2 mm at both ends of the first cylindrical portion (φ8 portion).

(Production of elastic roller)
An apparatus having a core bar supply mechanism, an elastic roller discharge mechanism, and a gripping mechanism was prepared in the crosshead extruder shown in FIG. The prepared stepped core metal was continuously supplied from the core metal supply mechanism to the crosshead. The conveying speed of the stepped mandrel was 60 mm / sec.

  A die having an inner diameter of 14.5 mm was attached to the crosshead, and the temperature of the extruder and the crosshead was adjusted to 80 ° C. in advance.

  FIG. 15 shows the regulating member used in this example. A pair of regulating members 1501 shown in FIG. 15 has a shape in which a semicircle having a radius R1 'is wound through an iron plate having a thickness of 5 mm. The radius R1 'was 6.8 mm. Then, as shown in FIG. 15 (b), the inner diameter La when the rubber composition layer 401 is sandwiched is 13.6 mm.

  A pair of gripping members 1601 used in this example is shown in FIG. The material and thickness were the same as those of the regulating member. Further, the radius R2 'was 5 mm. Then, as shown in FIG. 16 (b), the inner diameter Lb when the rubber composition layer 401 is closed is 10 mm.

  With this gripping member, a range of 5 mm from the end of the cored bar was gripped. Moreover, the range of 5 mm from the edge part of the 1st cylindrical part was urged | biased by the control member.

  Thereafter, after the stepped core metal coated with the rubber composition progressed for a predetermined length, the rubber composition was cut with a cutter, and the stepped core metal coated with the rubber composition was discharged by a discharge mechanism. The outer diameter of the central portion of the first cylindrical portion covered with the rubber composition was φ14.2 mm.

  Next, a stepped cored bar covered with an unvulcanized rubber composition was placed in a hot air vulcanizing furnace preliminarily heated to an atmosphere of 170 ° C. with hot air, and heat vulcanized for 60 minutes. . Thereafter, excess rubber around the second cylindrical portion is cut and removed so that the length of the rubber is 328 mm, and an elastic roller having an elastic layer formed on the first cylindrical portion of the stepped core metal (Conductive roller) was obtained.

In the obtained elastic roller, it was confirmed whether or not the end portion of the elastic layer was in close contact with the entire circumference of the cored bar. Evaluation was made according to the following criteria.
A: The ends of the elastic layer are in close contact with the entire circumference of the cored bar.
B: Although the end of the elastic layer is peeled off at one part of the entire circumference of the cored bar, there is no problem in use.
C: The edge part of the elastic layer has produced remarkable peeling from the core metal.

  The evaluation results are shown in Table 1.

  Next, by polishing the surface of the elastic layer with a rotating grindstone, the crown has a diameter of 12.7 mm at the end and a diameter of 13.0 mm at the center, and the ten-point average roughness (Rz) of the surface is 6.3 μm. An elastic roller having conductivity with a runout of 21 μm was obtained.

(Preparation of surface layer)
Methyl isobutyl ketone was added to the caprolactone-modified acrylic polyol solution to adjust the solid content to 18% by mass.

For 555.6 parts by mass of this solution (corresponding to 100 parts by mass of the solid content of the acrylic polyol solution),
Carbon black (HAF): 16 parts by mass Acicular rutile-type titanium oxide fine particles: 35 parts by mass (surface treatment was performed with hexamethylene disilazane and dimethyl silicone. The approximate shape was an average particle size of 0.015 μm, and the vertical: horizontal = 3: 1)
Modified dimethyl silicone oil: 0.1 part by mass A 7: 3 mixture of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) 7: 3 mixture: 80.14 parts by mass was prepared. At this time, the mixture of the block HDI and the block IPDI was added so that “NCO / OH = 1.0”.

  Next, 210 g of the above mixed solution and 200 g of glass beads having an average particle diameter of 0.8 mm as a medium were mixed in a 450 mL glass bottle and dispersed for 24 hours using a paint shaker disperser. After dispersion, 5.44 parts by mass (corresponding to 20 parts by mass with respect to 100 parts by mass of the solid content of the acrylic polyol solution) of cross-linked acrylic particles “MR50G” (trade name, manufactured by Soken Chemical) as resin particles are added. Further, the resultant was dispersed for 30 minutes to obtain a coating material for forming a surface layer.

  This surface layer forming coating material was dipped on an elastic roller once and air-dried at room temperature for 30 minutes or more. Subsequently, it was dried for 1 hour with a hot air circulating dryer set to 90 ° C., and further dried for 1 hour with a hot air circulating dryer set to 160 ° C. to form a surface layer on the elastic layer surface of the elastic roller. . The dipping coating dipping time is 9 seconds, the dipping coating lifting speed is adjusted so that the initial speed is 20 mm / s, and the final speed is 2 mm / s. Between 20 mm / s and 2 mm / s is linear with respect to time. The speed was changed. In this way, a charging roller having a surface layer was produced.

  The obtained charging roller was subjected to image evaluation using an apparatus as shown below. The electrophotographic laser printer used in this test is an A3 machine for vertical output, the output speed of the recording medium is 94 mm / sec, and the image resolution is 600 dpi. The photosensitive member is a reversal developing type photosensitive drum in which an organic photosensitive layer having a film thickness of 18 μm is coated on an aluminum cylinder. The toner was obtained by polymerizing a random copolymer of styrene and butyl acrylate containing a charge control agent, a pigment and the like centering on wax, and further polymerizing a thin polyester layer on the surface to externally add silica fine particles. This toner is a polymerized toner having a glass transition temperature of 63 ° C. and a volume average particle diameter of 6 μm.

All image evaluations were performed in a low-temperature and low-humidity environment (15 ° C, 10% Rh), and a halftone image (an image that draws a horizontal line with a width of 1 dot and an interval of 2 dots in the direction perpendicular to the rotation direction of the photoreceptor) was output. went. Evaluation was made according to the following criteria.
A: Good image quality B: Some slight decrease in image quality is observed, but no problem in practical use C: Significant decrease in image quality The evaluation results are shown in Table 1.

(Example 2)
Example 1 was followed in Example 1 except that the radius R1 ′ of the semicircular penetrating portion of the regulating member was 6.5 mm. La is 13.0 mm. The evaluation results are shown in Table 1.

(Example 3)
Example 1 was followed in Example 1 except that the radius R1 ′ of the semicircular penetrating portion of the regulating member was 7.05 mm. La is 14.1 mm. The evaluation results are shown in Table 1.

Example 4
Example 1 was followed except that the radius R2 ′ of the semicircular penetrating portion of the gripping member in Example 1 was set to 3.8 mm. La is 13.6 mm and Lb is 7.6 mm. The evaluation results are shown in Table 1.

(Example 5)
Example 1 was followed in Example 1 except that the radius R2 ′ of the semicircular penetrating portion of the gripping member was 6.05 mm. . La is 13.6 mm. Lb is 12.1 mm. The evaluation results are shown in Table 1.

(Example 6)
Example 1 was followed in Example 1 except that the radius R1 ′ of the semicircular penetrating portion of the regulating member was 7.05 mm and the radius R2 ′ of the semicircular penetrating portion of the gripping member was 6.05 mm. La is 14.1 mm and Lb is 12.1 mm. The evaluation results are shown in Table 1.

(Example 7)
Example 1 is the same as Example 1 except that the radius R1 ′ of the semicircular penetrating portion of the biasing member is 7.05 mm and the radius R2 ′ of the semicircular penetrating portion of the gripping member is 3.8 mm. . La is 14.1 mm and Lb is 7.6 mm. The evaluation results are shown in Table 1.

(Example 8)
In Example 1, the radius R1 ′ of the semicircular penetrating portion of the biasing member was 6.5 mm, and the radius R2 ′ of the semicircular penetrating portion of the gripping member was 6.05 mm. . La is 13 mm and Lb is 12.1 mm. The evaluation results are shown in Table 1.

Example 9
Example 1 was followed in Example 1 except that the radius R1 ′ of the semicircular penetrating portion of the regulating member was 6.5 mm and the radius R2 ′ of the semicircular penetrating portion of the gripping member was 3.8 mm. La is 13 mm, and Lb is 7.6 mm. The evaluation results are shown in Table 1.

(Example 10)
Example 1 was followed in Example 1 except that the radius R2 ′ of the semicircular penetrating portion of the gripping member was 6.1 mm. La is 13.6 mm and Lb is 12.2 mm. The evaluation results are shown in Table 1.

(Example 11)
In Example 1, Example 1 was followed except that the radius R2 ′ of the semicircular penetrating portion of the gripping member was set to 3.75 mm. La is 13.6 mm, and Lb is 7.5 mm. The evaluation results are shown in Table 1.

(Example 12)
Example 1 was followed in Example 1 except that the radius R1 ′ of the semicircular penetrating portion of the regulating member was set to 7.1 mm. The inner diameter of the regulating member was the same as the outer diameter of the rubber composition layer, and no urging was performed by the regulating member. Lb is 10 mm. The evaluation results are shown in Table 1.

(Example 13)
Example 1 was followed in Example 1 except that the radius R1 ′ of the semicircular penetrating portion of the regulating member was 6.45 mm. La is 12.9 mm and Lb is 10 mm. The evaluation results are shown in Table 1.

(Example 14)
Example 1 was followed in Example 1 except that the radius R1 ′ of the semicircular penetrating portion of the regulating member was 7.1 mm and the radius R2 ′ of the semicircular penetrating portion of the gripping member was 6.1 mm. The inner diameter of the regulating member was the same as the outer diameter of the rubber composition layer, and no urging was performed by the regulating member. Lb is 12.2 mm. The evaluation results are shown in Table 1.

(Example 15)
Example 1 was followed in Example 1 except that the radius R1 ′ of the semicircular penetrating portion of the regulating member was 6.45 mm and the radius R2 ′ of the semicircular penetrating portion of the gripping member was 3.75 mm. La is 12.9 mm, and Lb is 7.5 mm. The evaluation results are shown in Table 1.

(Comparative Example 1)
Example 1 was followed except that the gripping member and the regulating member were not used. The rubber peeled off remarkably and the roller was not produced.

The schematic sectional drawing of the longitudinal direction of a stepped cored bar. Schematic which shows the state which the elastic layer peeled from the metal core. The schematic sectional drawing of the longitudinal direction of an elastic roller. The schematic explanatory drawing of the manufacturing method of the elastic roller which concerns on this invention. The schematic sectional drawing which shows the stepped core metal by which the rubber composition was coat | covered with the crosshead around. The schematic explanatory drawing of the state which the rubber composition layer distorted outside at the time of holding | grip. Schematic explanatory drawing of the manufacturing process (2) of the elastic roller which concerns on this invention. Schematic explanatory drawing for demonstrating a control member. Schematic which shows the one aspect | mode of the holding | grip and control member used for this invention. Schematic which shows the one aspect | mode of the holding | grip and control member used for this invention. Schematic which shows the one aspect | mode of the holding | grip and control member used for this invention. Schematic which shows the one aspect | mode of the holding | grip and control member used for this invention. Schematic which shows the one aspect | mode of the holding | grip and control member (integral type) used for this invention. Schematic which shows the one aspect | mode of the holding | grip and control member (integral type) used for this invention. The schematic explanatory drawing of the control member used for the Example of this invention. The schematic explanatory drawing of the holding member used for the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Stepped metal core 102 1st cylindrical part 103 2nd cylindrical part 201 Core metal 202 Elastic layer 301 Rubber elastic layer 401 Unvulcanized rubber composition layer 402 Crosshead 403 Extruder 404 Support member 405 Holding member 406 Restriction Member 407 Mandrel supply unit 408 Cutter 601 Rubber composition layer 602 surrounding the periphery from the gripping position to the first cylindrical portion 602 Diameter of the rubber composition layer covering the peripheral surface of the first cylindrical portion 603 Second cylinder Diameter of the rubber composition layer surrounding the part 604 Separation of the rubber composition at the end of the first cylindrical part 605 Gripping member 705 Gripping member 706 Restricting member 901a-b Parts constituting the grasping member or the regulating member 902 Rubber composition Surface in contact with an object (arc shape)
903 Flanks 1001a to 1001d Parts 1501 constituting the gripping member or the regulating member 1601 Parts constituting the regulating member used in the example 1601 Parts constituting the gripping member used in the example

Claims (2)

(1) A first cylindrical portion having a radius R1 and a second cylindrical portion having a radius R2 smaller than the radius R1 and connected to both ends of the first cylindrical portion and coaxial with the first cylindrical portion. The core bar is passed through a cross head, and the rubber composition is extruded around the core bar over the entire length of the core bar, thereby covering the peripheral surface of the first cylindrical portion with the layer of the rubber composition. And surrounding the second cylindrical portion with a layer of the rubber composition;
(2) The rubber composition layer surrounding the second cylindrical portion of the mandrel after passing through the crosshead is positioned outside the rubber composition layer at a position away from the first cylindrical portion. A method of manufacturing an elastic roller having a step of gripping with a gripping member and bringing a layer of the rubber composition into contact with a peripheral surface of the second cylindrical portion,
In the step (2), the rubber composition layer surrounds the second cylindrical portion on the side closer to the first cylindrical portion than the position where the layer of the rubber composition is in contact with the peripheral surface of the second cylindrical portion. Restricting the outer diameter of the rubber composition layer to be larger than the outer diameter of the rubber composition layer covering the peripheral surface of the first cylindrical portion as the rubber composition is gripped by the gripping member. A method for manufacturing an elastic roller, which is performed while 2. The method of manufacturing an elastic roller according to claim 1, wherein the gripping member is composed of at least two parts, grips the rubber composition layer so as to be sandwiched from outside by the parts, and contacts the second cylindrical portion. .

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