JP2013194095A - Method for producing cylindrical foamed rubber, conductive roller and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a cylindrical foamed rubber, capable of regularly stably producing a cylindrical foamed rubber which has a stabilized inside diameter dimension with outer peripheral and inner peripheral cross-sectional shapes thereof being as circular as possible, and also has even hardness or conductivity with a uniformed distribution of cells, without being limited in blending or crosslinking/expanding conditions or the like and further without being affected by a material lot difference, a weather change or the like; a conductive roller with stabilized shape and characteristics, which is provided with a roller body composed of the cylindrical foamed rubber produced by the method; and an image forming apparatus having performances stabilized by incorporating the conductive roller.SOLUTION: In a method for producing a cylindrical foamed rubber, simultaneously with or after extrusion molding of a cylindrical body 4 that is a base of the cylindrical foamed rubber, a continuous slit 17 is formed, along the axial direction of the cylindrical body, on an outer peripheral surface 12 of the cylindrical body 4 before crosslinking and expanding. A conductive roller is provided with a cylindrical roller body composed of the cylindrical foamed rubber. An image forming apparatus includes the conductive roller incorporated thereto.

Description

  The present invention relates to a method for producing a cylindrical foam rubber, a conductive roller having a roller body made of the cylindrical foam rubber produced by the production method using a conductive rubber composition, and the conductive roller. The present invention relates to an incorporated image forming apparatus.

For example, in an image forming apparatus using electrophotography such as a laser printer, an electrostatic copying machine, a plain paper facsimile machine, or a complex machine of these, paper (plastic film such as an OHP film) is roughly processed through the following steps. An image is formed on the surface of the same.
First, the surface of the photoconductive photoconductor is exposed in a uniformly charged state, and an electrostatic latent image corresponding to the formed image is formed on the surface (charging step → exposure step).

Next, the toner, which is minute colored particles, is brought into contact with the surface of the photoconductor in a state of being charged to a predetermined potential. Then, the toner is selectively attached to the surface of the photoconductor according to the potential pattern of the electrostatic latent image, and the electrostatic latent image is developed into a toner image (development process).
Next, the toner image is transferred to the surface of the paper (transfer process) and further fixed (fixing process), whereby an image is formed on the surface of the paper.

In the transfer step, the toner image formed on the surface of the photoconductor is not only directly transferred to the surface of the paper, but also transferred to the surface of the image carrier (primary transfer step) and then transferred to the surface of the paper. In some cases, retransfer is performed (secondary transfer process).
Further, a series of image formation is completed by removing the toner remaining on the surface of the photoreceptor after the transfer (cleaning process).

Of the above processes, a conductive roller having a roller body provided with conductivity according to each application is widely used in the charging process, developing process, transfer process, and cleaning process of the photoreceptor.
The roller body is formed by extruding a rubber composition containing a conductivity imparting agent and a foaming agent into a cylindrical shape through a die of an extruder, and continuously crosslinking and foaming the extruded cylindrical body. It is manufactured by further cutting the manufactured cylindrical foam rubber into a predetermined length.

In addition, in order to continuously crosslink and foam the cylindrical body as fast as possible, a continuous crosslinking apparatus including a microwave crosslinking apparatus and a hot-air crosslinking apparatus is preferably used for the crosslinking and foaming process (for example, Patent Documents). 1 and 2 etc.).
A conductive roller is manufactured by inserting a metal shaft, for example, into the cylinder of the roller body manufactured through the above steps and fixing them to each other.

  The roller body is generally formed such that the cross-sectional shape of the outer peripheral surface and the inner peripheral surface of the cylinder in a cross section orthogonal to the axial direction is circular. Therefore, as the die of the extruder for extruding the cylindrical body that becomes the basis of the roller body, the outer peripheral edge corresponding to the outer peripheral surface of the opening and the plane of the inner peripheral edge corresponding to the inner peripheral surface A shape whose shape is both circular is used.

  However, the cylindrical foamed rubber produced by extrusion molding through the die, followed by foaming and curing has a cross-sectional shape of the outer peripheral surface and inner peripheral surface in a clean circle corresponding to the outer peripheral edge and inner peripheral edge of the base. However, there are problems that the ratio of the major axis to the minor axis is significantly larger than 1, the dimension of the inner diameter is not uniform, the cell distribution is not uniform, and the hardness and conductivity are likely to be uneven. is there.

The cause of these issues is
-Normally, the gas generated from the foaming agent and the resulting foaming pressure in the tubular body that is being continuously cross-linked and foamed while being transported along a substantially horizontal direction are the vertical direction of the tubular body. Easy to concentrate on the area above
・ In particular, foaming proceeds rapidly in a short time by using the continuous crosslinking apparatus,
Foaming does not progress uniformly throughout the tubular body, and local and abnormal foaming is likely to occur where the surface of the unspecified part of the tubular body (the outer peripheral surface and inner peripheral surface of the tube) swells extremely. It seems that there is.

  Therefore, the cylindrical foamed rubber manufactured by the above manufacturing method has the outer peripheral surface and the inner peripheral surface as close to a circular shape as possible to stabilize the inner diameter dimension, and the distribution of cells is uniform and the hardness and conductivity are uneven. In order to produce a cylindrical foam rubber having no crack, for example, adjustment of the composition of the rubber composition or adjustment of the crosslinking / foaming conditions has been studied (see, for example, Patent Documents 4 to 7).

Japanese Patent Laid-Open No. 2002-221859 JP 2006-117870 A JP 2006-171644 A JP 2007-322654 A JP 2008-90236 A JP 2010-140034 A JP 2011-70202 A

As described above, the method of adjusting the blending of the rubber composition or adjusting the crosslinking / foaming conditions significantly restricts the blending and the crosslinking / foaming conditions, so that, for example, performance as a conductive roller is good. There are problems such as cases where blending cannot be adopted and cases where efficient crosslinking and foaming conditions cannot be set in consideration of the balance with the speed of extrusion molding.
In the above-described method, for example, abnormal foaming suddenly occurring due to material lot differences, climate change, and the like, the deformation of the cross-sectional shape of the cylindrical foamed rubber, the non-uniformity of the inner diameter, or the non-uniform distribution of the cells. There is also a problem that it is not possible to prevent the occurrence of uneven hardness and electrical conductivity.

  The purpose of the present invention is not limited by the blending, cross-linking / foaming conditions, etc., and the cross-sectional shape of the outer peripheral surface and the inner peripheral surface is as circular as possible without affecting the material lot difference, climate change, etc. An object of the present invention is to provide a method for producing a cylindrical foamed rubber, which can stably produce a cylindrical foamed rubber that is stable and has a uniform cell distribution and no unevenness in hardness and conductivity. Another object of the present invention is to provide a conductive roller having a roller body made of cylindrical foamed rubber manufactured by the above manufacturing method and having a stable shape and characteristics, and an image having a stable performance by incorporating the conductive roller. It is to provide a forming apparatus.

  The present invention is a production method for producing a tubular foamed rubber by continuously crosslinking and foaming a rubber composition containing a foaming agent through a die of an extruder while being extruded into a tubular shape. A continuous cut along the axial direction of the cylindrical body on the outer peripheral surface of the cylindrical body before or after the extrusion molding and before crosslinking and foaming. Including a step of putting in the cake.

According to the present invention, a continuous notch along the axial direction of the cylindrical body at the outer peripheral surface of the cylindrical body at the same time as the extrusion of the cylindrical body or before the crosslinking and foaming after the extrusion molding. By inserting, excess gas generated from the foaming agent during crosslinking and foaming and the resulting foaming pressure can be quickly and efficiently released to the outside of the cylindrical body through the cut.
That is, in extrusion molding, a very thin film having a high density is formed on the outer peripheral surface and the inner peripheral surface of the cylindrical body in contact with the die, and the coating forms a gas generated from the foaming agent and the resulting foaming pressure. It functions in order to be contained in a cylindrical body and to efficiently foam the cylindrical body. However, the above-mentioned coating film may cause various problems described above because it does not escape excessively generated gas.

On the other hand, according to the present invention, a gas passage is formed in a part of the coating by making a cut in the outer peripheral surface, so that the gas generated from the foaming agent and the resulting foaming pressure are moved out of the cylindrical body. It becomes possible to escape moderately.
Also, by making a cut in the outer peripheral surface, the area of the interface between the outer peripheral surface and the outside air that functions to release the gas generated from the foaming agent and the resulting foaming pressure to the outside of the cylindrical body may increase. This is one of the reasons why the gas and the resulting foaming pressure can be quickly released out of the cylindrical body.

Therefore, according to the present invention, the composition, cross-linking / foaming conditions, etc. are not limited, and the outer and inner peripheral surfaces are as circular as possible, for example, without being affected by material lot differences, climate change, etc. However, it is possible to always stably produce a cylindrical foam rubber having a uniform cell distribution and no unevenness in hardness and conductivity.
In the present invention, a protrusion projecting inwardly from the outer peripheral edge is provided on the outer peripheral edge of the opening of the base, and the cylindrical shape is formed on the outer peripheral surface of the cylindrical body that is extruded through the base by the protrusion. Using a cutting edge or a needle tip fixed in the vicinity of the die on the outer peripheral surface of the cylindrical body after making a continuous cut along the axial direction of the body or before extrusion and crosslinking and foaming, the cylinder It is preferable to make continuous cuts along the axial direction of the body.

According to these configurations, it is possible to make a certain cut surely and always on the outer peripheral surface of the cylindrical body while minimizing the mechanism for making the cut with as few movable parts as possible.
Further, in the present invention, the cylindrical body is continuously cross-linked and foamed while being transported along a substantially horizontal direction, and is positioned at least above the outer peripheral surface of the cylindrical body in the transport state in the vertical direction. It is preferable to make a continuous cut along the axial direction of the cylindrical body at one place.

Thereby, as described above, the gas and the foaming pressure concentrated in the upper region in the vertical direction of the cylindrical body that is continuously cross-linked and foamed while being conveyed along the substantially horizontal direction are cut off. It is possible to escape from the cylindrical body more efficiently and effectively through the insertion.
Therefore, a cylindrical foam rubber with stable quality that has a circular cross-sectional shape on the outer peripheral surface and inner peripheral surface, a stable inner diameter, a uniform cell distribution, and no unevenness in hardness or conductivity. Can be manufactured.

This invention is a conductive roller provided with the cylindrical roller main body which consists of a cylindrical foamed rubber manufactured by the manufacturing method of the previous invention using the conductive rubber composition.
According to the present invention, the cylindrical foamed rubber manufactured by the manufacturing method of the present invention is used, and the cross-sectional shape of the outer peripheral surface and the inner peripheral surface is as circular as possible, the inner diameter is stable, and the cell distribution is It is possible to provide a conductive roller having a roller body that is uniform and has no unevenness in hardness or conductivity.

The present invention is an image forming apparatus in which the conductive roller of the present invention is incorporated.
According to the present invention, it is possible to provide an image forming apparatus with stable performance by incorporating a conductive roller having a roller body with stable shape and characteristics as described above.

  According to the present invention, the composition, cross-linking / foaming conditions, etc. are not restricted, and the cross-sectional shape of the outer peripheral surface and the inner peripheral surface is as circular as possible and the inner diameter dimension is stable without being affected by material lot differences or climate change. In addition, it is possible to provide a method for producing a tubular foamed rubber that can always produce a tubular foamed rubber having a uniform cell distribution and no unevenness in hardness and conductivity. Further, according to the present invention, a conductive roller having a roller body made of cylindrical foam rubber manufactured by the manufacturing method and having a stable shape and characteristics, and an image having a stable performance by incorporating the conductive roller. A forming apparatus can be provided.

It is a block diagram explaining an example of embodiment of the manufacturing method of the cylindrical foamed rubber of this invention. It is a perspective view which shows an example of a nozzle | cap | die used for the process of making a notch simultaneously with extrusion molding in the outer peripheral surface of the cylindrical body at the time of extrusion molding among the manufacturing methods of the example of FIG. It is a perspective view explaining the process of making a notch simultaneously with extrusion molding in the outer peripheral surface of the cylindrical body at the time of extrusion molding using the nozzle | cap | die of the example of FIG. It is a perspective view explaining the process of making a notch in the outer peripheral surface of the cylindrical body before bridge | crosslinking and foaming after extrusion molding among the manufacturing methods of the said example. It is a perspective view which shows an example of the electroconductive roller provided with the roller main body which consists of cylindrical foamed rubber manufactured by the said manufacturing method.

<< Method for producing cylindrical foam rubber >>
FIG. 1 is a block diagram illustrating an example of an embodiment of a method for producing a cylindrical foam rubber according to the present invention.
Referring to FIG. 1, a manufacturing apparatus 1 used in the manufacturing method of this example includes an extruder 3 for continuously extruding a rubber composition through a base 2 into a cylindrical shape, and the continuous extrusion molding. The continuous foaming device 6 for forming the tubular foamed rubber 5 by crosslinking and foaming while transporting the tubular body 4 in a long length without being cut, and the tubular foamed rubber 5 at a constant speed. A take-up machine 7 is provided.

The continuous cross-linking device 6 includes a microwave cross-linking device 8 and hot air that are sequentially arranged on the way of transporting the long cylindrical body 4 continuously along a substantially horizontal direction by a conveyor or the like (not shown). A cross-linking device 9 is provided.
In order to manufacture the cylindrical foamed rubber 5 using the manufacturing apparatus 1, first, a rubber composition that is formed into a ribbon shape or the like by kneading components such as rubber and a foaming agent that are the basis of the cylindrical foamed rubber 5. The long cylindrical body 4 is continuously extruded through the die 2 by operating the extruder 3 while continuously supplying the product to the extruder 3.

  Next, while continuously conveying the extruded cylindrical body 4 along the substantially horizontal direction at a constant speed by the conveyor and the take-up machine 7, the microwave crosslinking apparatus is first of the continuous crosslinking apparatus 6. The rubber composition that forms the cylindrical body 4 is crosslinked to a certain degree of crosslinking by irradiating microwaves by passing through 8. Moreover, the inside of the microwave bridge | crosslinking apparatus 8 can be heated to fixed temperature, and a rubber composition can also be made to foam with the said bridge | crosslinking.

Next, the rubber composition is further foamed by passing through the hot air bridging device 9 while continuing the conveyance, and the rubber composition is further foamed, and the rubber composition is crosslinked to a predetermined degree of crosslinking. The cylindrical foamed rubber 5 is continuously manufactured by allowing the resin to pass through and cooling.
In the manufacturing method of this example using the manufacturing apparatus 1, the cylindrical body 4 is extruded through the die 2 at the same time as or after the extrusion, and then transferred to the continuous crosslinking apparatus 6 before being crosslinked and foamed. A step of making continuous cuts along the axial direction of the cylindrical body 4 on the outer peripheral surface of the cylindrical body 4 is included.

Thereby, the excess gas generated from the foaming agent and the resulting foaming pressure can be released out of the cylindrical body 4 through the cut.
Therefore, the composition, crosslinking, foaming conditions, etc. are not limited, and the outer and inner peripheral surfaces are as circular as possible, and the inner diameter is stable, without being affected by material lot differences, climate change, etc. The cylindrical foamed rubber 5 having a uniform cell distribution and no unevenness in hardness and conductivity can always be manufactured stably.

FIG. 2 is a perspective view showing an example of a die used in a step of making a cut at the same time as extrusion molding on the outer peripheral surface of a cylindrical body during extrusion molding in the manufacturing method of the example of FIG. FIG. 3 is a perspective view for explaining a process of making a cut at the same time as the extrusion with the outer peripheral surface of the cylindrical body at the time of extrusion molding using the die of the example of FIG.
2 and 3, the base 2 is provided with an opening 11 for extruding the rubber composition on the front surface 10 thereof.

The outer peripheral edge 13 corresponding to the outer peripheral surface 12 of the cylindrical body 4 and the inner peripheral edge 15 corresponding to the inner peripheral surface 14 of the cylindrical body 4 of the opening 11 are respectively circular in the outer peripheral surface 12 and the inner peripheral surface 14. It is formed in a circle according to the cross-sectional shape.
A projection 16 is provided on the outer peripheral edge 13 so as to protrude from the outer peripheral edge 13 to the inside of the opening 11. In the example shown in the figure, the protrusions 16 are provided at two locations on the outer peripheral edge 13 at the uppermost and lowermost positions in the vertical direction.

Each of the protrusions 16 is formed in a substantially triangular shape in which the planar shape of the front surface 10 of the base 2 constituting the outer peripheral edge 13 is pointed toward the inside of the opening 11. Further, the protrusion 16 is formed in a wedge shape in which the width and the protrusion amount gradually decrease from the opening 11 of the base toward the inner depth.
By using the base 2 provided with the projections 16, the cylindrical body 4 extruded through the base 2 has one outer peripheral surface 12 positioned at the top in the vertical direction and the outer peripheral surface 12. A continuous cut 17 along the axial direction of the cylindrical body 4 is formed at one position located at the lowest position in the vertical direction.

As a result, as described above, excess gas generated from the foaming agent at the time of crosslinking and foaming and the resulting foaming pressure can be efficiently and quickly released to the outside of the cylindrical body 4 through the cuts 17.
Therefore, the blending, cross-linking / foaming conditions, etc. are not limited, and the outer peripheral surface 12 and the inner peripheral surface 14 are as circular as possible and the inner diameter is stable without being affected by, for example, material lot differences or climate change. In addition, it is possible to always stably produce the cylindrical foamed rubber 5 having a uniform cell distribution and no unevenness in hardness and conductivity.

In particular, the notch 17 provided at one place (upper side in FIG. 3) located at the uppermost position in the vertical direction is the vertical direction of the tubular body 4 that is continuously bridged and foamed while being conveyed along the substantially horizontal direction. It functions in order to let the gas and the foaming pressure concentrated in the region above the gas to the outside of the cylindrical body 4 more efficiently and effectively.
Therefore, a cylindrical foam rubber having a stable quality in which the cross-sectional shapes of the outer peripheral surface 12 and the inner peripheral surface 14 are circular, the inner diameter is stable, the cell distribution is uniform, and there is no unevenness in hardness or conductivity. 5 can be manufactured.

FIG. 4 is a perspective view for explaining a step of making a cut in the outer peripheral surface of the tubular body after extrusion molding and before crosslinking and foaming in the manufacturing method of the above example.
Referring to FIG. 4, in this example, instead of providing a protrusion 16 on the outer peripheral edge 13 of the opening 11 of the base 2, the downstream side in the transport direction of the cylindrical body 4 from the opening 11 of the base 2 (front side in the figure). A cutting edge 18 of a knife or cutter is fixed to the outer peripheral surface 12 of the tubular body 4 extruded from the base 2 by the cutting edge 18.

  The base 2 is configured similarly to the example of FIG. 2 except that the protrusion 16 is not provided. That is, the base 2 is provided with an opening 11 for extruding the rubber composition on the front surface 10 thereof. Moreover, the outer peripheral edge 13 corresponding to the outer peripheral surface 12 of the cylindrical body 4 and the inner peripheral edge 15 corresponding to the inner peripheral surface 14 of the cylindrical body 4 of the opening 11 are respectively circular in the outer peripheral surface 12 and the inner peripheral surface 14. It is formed in a circle according to the cross-sectional shape.

In the example shown in the figure, the cutting edge 18 is provided at one uppermost position in the vertical direction of the outer peripheral surface 12 of the cylindrical body 4, and a cylinder that is extruded through the die 2 by using the cutting edge 18. A continuous notch 17 along the axial direction of the cylindrical body 4 is formed in the cylindrical body 4 at one location on the outer peripheral surface 12 located at the uppermost position in the vertical direction.
Therefore, the gas and the foaming pressure concentrated in the upper region in the vertical direction of the cylindrical body 4 continuously cross-linked and foamed while being conveyed along the substantially horizontal direction can be more efficiently passed through the notch 17. Effectively escape from the cylindrical body 4, the cross-sectional shape of the outer peripheral surface 12 and the inner peripheral surface 14 is circular, the inner diameter is stable, the cell distribution is uniform, and the hardness and conductivity are uneven. It is possible to produce a cylindrical foam rubber 5 having no quality and stable quality.

The cuts 17 formed on the outer peripheral surface 12 of the cylindrical body 4 by the protrusions 16 and the blade edges 18 are finally closed by the bridging and foaming of the cylindrical body 4. Some traces may remain on the outer peripheral surface 12, but such minute traces can be removed by, for example, polishing for finishing the outer peripheral surface 12.
The protrusion height of the projection 16 inward in the radial direction, the width of the base, or the penetration depth of the blade edge 18 from the outer peripheral surface 12 into the cylindrical body 4 can be arbitrarily set, but when these are too large There is a possibility that the notch 17 becomes too deep and a large trace remains after the tubular body 4 is crosslinked and foamed. Therefore, the height and width of the protrusion 16 are both 2 mm or less, and particularly preferably 1.5 mm or less. Similarly, the penetration depth of the blade edge 18 is preferably 2 mm or less, particularly preferably 1.5 mm or less.

  However, if the height and width of the protrusion 16 or the penetration depth of the cutting edge is too small, the effect of releasing the gas and the foaming pressure described above may be insufficient. Therefore, it is preferable that the height and width of the protrusion 16 are both 0.3 mm or more, particularly 0.7 mm or more. Similarly, the penetration depth of the blade edge 18 is preferably 0.3 mm or more, particularly 0.7 mm or more.

  As shown in FIG. 4, the notch 17 is located at one place located at the uppermost position in the vertical direction, or at one place located at the uppermost position in the vertical direction as shown in FIG. 3, and at the lowermost position in the vertical direction. It is effective to provide a total of two locations, one located. In particular, the single notch 17 located at the uppermost position in the vertical direction efficiently allows the gas and the foaming pressure concentrated in the upper region of the cylindrical body 4 to efficiently form the cylindrical shape, as described above. It functions to escape from the body 4.

However, in some cases, the notches 17 may be formed at three or more locations in the circumferential direction of the outer peripheral surface 12.
Instead of the cutting edge 18 of the knife or the cutter in FIG. 4, a cut 17 may be made in the outer peripheral surface 12 of the cylindrical body 4 with a needle tip or a cutting edge of a rotary blade, for example.
The cylindrical foamed rubber 5 produced by the production method of the present invention can be used for various applications, and in particular, by imparting conductivity to the cylindrical foamed rubber 5 by using a conductive rubber composition, It is preferably used for forming a roller body of a conductive roller incorporated in an image forming apparatus.

According to this manufacturing method, as described above, the outer peripheral surface and the inner peripheral surface of the roller body are as circular as possible in cross section, the inner diameter is stable, the cell distribution is uniform, and the hardness and conductivity are uneven. Therefore, a conductive roller having a stable shape and characteristics can be provided.
《Conductive roller》
FIG. 5 is a perspective view showing an example of a conductive roller provided with a roller body made of cylindrical foam rubber 5 manufactured by the manufacturing method.

Referring to FIG. 5, the conductive roller 19 of this example is obtained by cutting the cylindrical foamed rubber 5 into a predetermined length, and further polishing the outer peripheral surface 20 as necessary to obtain a predetermined outer diameter and A roller main body 21 finished to have a surface roughness and a shaft 23 inserted through a through hole 22 at the center of the roller main body 21 are provided.
The shaft 23 is integrally formed of a metal such as aluminum, an aluminum alloy, or stainless steel. The roller body 21 and the shaft 23 are electrically joined together by, for example, a conductive adhesive and are mechanically fixed and integrated to form the conductive roller 19.

As the conductive rubber composition used as the basis of the roller body 21, a composition having an arbitrary composition according to the use of the conductive roller 19 can be used.
In particular, a conductive rubber composition imparted with ionic conductivity using an ionic conductive rubber also serving as a rubber component is preferred as the conductivity imparting agent.
<< Conductive rubber composition >>
<Ion conductive rubber>
As the rubber component, it is preferable to use the ion conductive rubber and the crosslinkable rubber in combination.

  Among these, as ionic conductive rubber, epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide binary copolymer (ECO), epichlorohydrin-propylene oxide binary copolymer, epichlorohydrin-allyl glycidyl ether binary copolymer, epichlorohydrin- 1 type of ethylene oxide-allyl glycidyl ether terpolymer (GECO), epichlorohydrin-propylene oxide-allyl glycidyl ether terpolymer, and epichlorohydrin-ethylene oxide-propylene oxide-allyl glycidyl ether quaternary copolymer Or 2 or more types are mentioned.

As the epichlorohydrin rubber, among the above examples, a copolymer containing ethylene oxide, particularly ECO and / or GECO is preferable.
In both copolymers, the ethylene oxide content is preferably 30 mol% or more, particularly preferably 50 mol% or more, and preferably 80 mol% or less.
Ethylene oxide serves to lower the roller resistance value of the conductive roller 19. However, when the ethylene oxide content is less than the above range, such a function cannot be sufficiently obtained, and therefore the roller resistance value of the conductive roller 19 may not be sufficiently reduced.

On the other hand, when the ethylene oxide content exceeds the above range, crystallization of ethylene oxide occurs and the segmental movement of the molecular chain is hindered, so that the roller resistance value of the conductive roller 19 tends to increase. In addition, the hardness of the roller body 21 after crosslinking may increase, or the viscosity of the conductive rubber composition before crosslinking may increase when heated and melted.
The epichlorohydrin content in ECO is the remaining amount of the ethylene oxide content. That is, the epichlorohydrin content is preferably 20 mol% or more, preferably 70 mol% or less, and particularly preferably 50 mol% or less.

Further, the allylic glycidyl ether content in GECO is preferably 0.5 mol% or more, particularly preferably 2 mol% or more, more preferably 10 mol% or less, and particularly preferably 5 mol% or less.
The allyl glycidyl ether itself functions to secure a free volume as a side chain, thereby suppressing the crystallization of ethylene oxide and reducing the roller resistance value of the conductive roller 19. However, if the allyl glycidyl ether content is less than the above range, such a function cannot be obtained, so that the roller resistance value of the conductive roller 19 may not be sufficiently reduced.

  On the other hand, allyl glycidyl ether functions as a crosslinking point at the time of GECO crosslinking, so when the allyl glycidyl ether content exceeds the above range, the GECO crosslinking density becomes high, and segment movement of molecular chains is hindered. On the contrary, the roller resistance value of the conductive roller 19 tends to increase. Further, the tensile strength, fatigue characteristics, bending resistance, etc. of the roller body 21 may be reduced.

The epichlorohydrin content in GECO is the remaining amount of the ethylene oxide content and the allyl glycidyl ether content. That is, the epichlorohydrin content is preferably 10 mol% or more, particularly 19.5 mol% or more, preferably 69.5 mol% or less, particularly preferably 60 mol% or less.
As GECO, in addition to a copolymer in the narrow sense obtained by copolymerizing the above three types of monomers, a modified product obtained by modifying epichlorohydrin-ethylene oxide copolymer (ECO) with allyl glycidyl ether is also known. Any GECO can be used in the present invention.

The blending ratio of epichlorohydrin rubber is preferably 5 parts by mass or more, particularly 10 parts by mass or more, and preferably 40 parts by mass or less, particularly 30 parts by mass or less, in 100 parts by mass of the total amount of rubber.
If the blending ratio is less than the above range, the roller body 21 may not be provided with good ionic conductivity.

On the other hand, when the above range is exceeded, the blending ratio of the crosslinkable rubber is relatively decreased, and there is a possibility that the effect obtained by blending various crosslinkable rubbers described later cannot be sufficiently obtained.
<Crosslinkable rubber>
Examples of the crosslinkable rubber include styrene butadiene rubber (SBR) and / or acrylonitrile butadiene rubber (NBR). These rubbers have a good crosslinkability and function to impart good rubber elasticity and flexibility to the roller body 21 after the crosslinking.

Further, when ethylene propylene diene rubber (EPDM) is further blended as the crosslinkable rubber, the resistance of the roller body 21 to ozone generated in the image forming apparatus can be improved.
(SBR, NBR)
Of these, as the SBR, any of various SBRs synthesized by copolymerizing styrene and 1,3-butadiene by various polymerization methods such as an emulsion polymerization method and a solution polymerization method can be used. In addition, as SBR, there are an oil-extended type in which flexibility is adjusted by adding an extending oil, and a non-oil-extended type in which flexibility is not added, either of which can be used.

Furthermore, as the SBR, any of SBR of high styrene type, medium styrene type, and low styrene type classified by styrene content can be used. Various physical properties of the roller body can be adjusted by changing the styrene content and the degree of crosslinking.
One or more of these SBRs can be used.
As NBR, any of low nitrile NBR, medium nitrile NBR, medium high nitrile NBR, high nitrile NBR, and extremely high nitrile NBR classified by acrylonitrile content can be used. One or more of these NBRs can be used.

Furthermore, SBR and NBR can be used in combination.
The blending ratio of SBR and / or NBR is preferably 40 parts by mass or more, particularly 60 parts by mass or more, and particularly 90 parts by mass or less, particularly 80 parts by mass or less, in 100 parts by mass of the total amount of rubber. preferable.
When the blending ratio is less than the above range, the effect of imparting good crosslinkability to the conductive rubber composition described above by using SBR and / or NBR, and good rubber for the roller body 21 after crosslinking There is a possibility that the effect of imparting elasticity and flexibility cannot be obtained sufficiently.

On the other hand, when the above range is exceeded, the blending ratio of EPDM is relatively reduced, and there is a possibility that good ozone resistance cannot be imparted to the roller body 21. Further, the blending ratio of epichlorohydrin rubber is relatively decreased, and there is a possibility that good ionic conductivity cannot be imparted to the roller body 21.
In addition, the said mixture ratio is a mixture ratio of SBR itself as solid content contained in the oil-extended type SBR when using an oil-extended type SBR. Moreover, when using SBR and NBR together, it is the total blending ratio.
(EPDM)
As EPDM, any of various EPDMs in which a double bond is introduced into the main chain by adding a small amount of a third component (diene component) to ethylene and propylene can be used. As the EPDM, various products are provided depending on the kind and amount of the third component. Representative examples of the third component include ethylidene norbornene (ENB), 1,4-hexadiene (1,4-HD), dicyclopentadiene (DCP), and the like. A Ziegler catalyst is generally used as the polymerization catalyst.

The blending ratio of EPDM is preferably 5 parts by mass or more, more preferably 40 parts by mass or less, and particularly preferably 20 parts by mass or less, in 100 parts by mass of the total rubber content.
If the blending ratio is less than the above range, there is a possibility that good ozone resistance cannot be imparted to the roller body 21.
On the other hand, when the above range is exceeded, the blending ratio of SBR and / or NBR becomes relatively small, and by blending these rubbers, the effect of imparting good crosslinkability to the conductive rubber composition In addition, there is a possibility that the effect of imparting good rubber elasticity and flexibility to the roller body 21 after crosslinking may not be sufficiently obtained. Further, the blending ratio of epichlorohydrin rubber is relatively reduced, and there is a possibility that good ionic conductivity cannot be imparted to the roller body.

(Other rubber)
As the rubber component, polar rubbers such as chloroprene rubber (CR), butadiene rubber (BR), and acrylic rubber (ACM) can be further blended to finely adjust the roller resistance value of the conductive roller 19.
<Foaming agent>
As the foaming agent, any of various foaming agents that can generate gas by heating to foam the conductive rubber composition can be used.

Examples of the foaming agent include azodicarbonamide (H ₂ NOCN = NCONH ₂ , ADCA), 4,4′-oxybis (benzenesulfonylhydrazide) (OBSH), N, N-dinitrosopentamethylenetetramine (DPT), and the like. 1 type or 2 types or more are mentioned.
The blending ratio of the foaming agent is preferably 1 part by mass or more, particularly 2 parts by mass or more, preferably 8 parts by mass or less, particularly 6 parts by mass or less, per 100 parts by mass of the total amount of rubber.

If the blending ratio is less than the above range, the cylindrical body 4 may not be foamed satisfactorily.
On the other hand, when the above range is exceeded, even if the notch 17 is made in the cylindrical body 4, the gas generated in a large amount and the foaming pressure caused by the gas are promptly passed out of the cylindrical body 4 through the notch 17. It is not possible to escape efficiently, and the outer peripheral surface of the cylindrical foam rubber 5 and the cross-sectional shape of the inner peripheral surface of the cylindrical foamed rubber 5 are not clean due to excessively contained gas and foaming pressure, or the inner diameter is uneven. In addition, the distribution of the cells is not uniform, and there is a risk of unevenness in hardness and conductivity.

You may mix | blend the foaming adjuvant which reduces the decomposition temperature of the said foaming agent and assists the foaming. As the foaming aid, urea is preferably used.
The blending ratio of the foaming aid is preferably 1 part by mass or more, particularly 2 parts by mass or more, preferably 5 parts by mass or less, particularly 3 parts by mass or less, per 100 parts by mass of the total amount of rubber.
If the blending ratio is less than the above range, the effect of assisting foaming of the foaming agent by the foaming aid cannot be sufficiently obtained, and the tubular body 4 may not be foamed satisfactorily.

  On the other hand, when the above range is exceeded, the foaming temperature of the foaming agent becomes too low, and foaming proceeds in a very short time. Therefore, even if the cut 17 is made in the cylindrical body 4, a large amount of gas is generated. And the foaming pressure caused thereby cannot be quickly and efficiently released through the notch 17 to the outside of the cylindrical body 4, and the outer peripheral surface and inner circumference of the cylindrical foamed rubber 5 due to excessively contained gas and foaming pressure. There is a possibility that the cross-sectional shape of the surface may be a clean circle, the inner diameter may be uneven, the cell distribution may be uneven, and the hardness and conductivity may be uneven.

<Crosslinking agent component>
The conductive rubber composition is blended with a crosslinking agent component for crosslinking the rubber component. Examples of the crosslinking agent component include a crosslinking agent and an accelerator.
Among these, examples of the crosslinking agent include one or more of sulfur-based crosslinking agents, thiourea-based crosslinking agents, triazine derivative-based crosslinking agents, peroxide-based crosslinking agents, various monomers, and the like. Of these, sulfur-based crosslinking agents are preferred.

Examples of sulfur-based crosslinking agents include powdered sulfur and organic sulfur-containing compounds. Among these, examples of the organic sulfur-containing compound include tetramethylthiuram disulfide and N, N-dithiobismorpholine. In particular, sulfur such as powdered sulfur is preferred.
The blending ratio of sulfur is preferably 0.2 parts by mass or more, particularly 1 part by mass or more, preferably 5 parts by mass or less, particularly 3 parts by mass or less, per 100 parts by mass of the total amount of rubber.

If the blending ratio is less than the above range, the cross-linking speed of the entire conductive rubber composition becomes slow, and the time required for cross-linking becomes long, and the productivity of the roller body may be lowered. When the above range is exceeded, there is a possibility that the compression set of the roller body after crosslinking becomes large or excessive sulfur blooms on the outer peripheral surface of the roller body.
Examples of the accelerator include inorganic accelerators such as slaked lime, magnesia (MgO), and resurge (PbO), and one or more organic accelerators.

  Examples of the organic accelerator include guanidine accelerators such as di-o-tolylguanidine, 1,3-diphenylguanidine, 1-o-tolylbiguanide, dicatechol borate di-o-tolylguanidine salt; 2-mercapto Thiazole accelerators such as benzothiazole and di-2-benzothiazyl disulfide; sulfenamide accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide; tetrametherthiuram monosulfide, tetramethylthiuram One type or two or more types of thiuram accelerators such as disulfide, tetraethylthiuram disulfide, and dipentamethylene thiuram tetrasulfide;

As the accelerator, one or more kinds of optimum accelerators may be selected from the various accelerators according to the type of the crosslinking agent to be combined. For example, when sulfur is used as a crosslinking agent, it is preferable to select and use a thiuram accelerator and / or a thiazole accelerator as an accelerator.
Moreover, since the acceleration | stimulation mechanism of a crosslinking agent changes with kinds, it is preferable to use 2 or more types together. The blending ratio of the individual accelerators used in combination can be arbitrarily set, but is preferably 0.1 parts by mass or more, particularly preferably 0.5 parts by mass or more, per 100 parts by mass of the total amount of rubber. Hereinafter, it is particularly preferably 2 parts by mass or less.

As the cross-linking agent component, an accelerator aid may be further blended.
Examples of the acceleration aid include one or more metal compounds such as zinc oxide; fatty acids such as stearic acid, oleic acid, and cottonseed fatty acid; and other conventionally known acceleration aids.
The blending ratio of the accelerator aid can be appropriately set according to the kind and combination of the rubber component, the kind and combination of the crosslinking agent and accelerator, and the like.

(Other)
You may mix | blend various additives with a conductive rubber composition as needed. Examples of the additive include acid acceptors, plastic components (plasticizers, processing aids, etc.), deterioration inhibitors, fillers, scorch inhibitors, ultraviolet absorbers, lubricants, pigments, antistatic agents, flame retardants, Examples thereof include a compatibilizer, a nucleating agent, and a co-crosslinking agent.

Of these, the acid-accepting agent functions to prevent the chlorine-based gas generated from the epichlorohydrin rubber during the crosslinking of the rubber from remaining in the roller body, thereby inhibiting the crosslinking and contamination of the photoreceptor.
As the acid acceptor, various substances that act as an acid acceptor can be used, but hydrotalcites or magsarat are preferable because of excellent dispersibility, and hydrotalcites are particularly preferable.

Further, when the hydrotalcite or the like is used in combination with magnesium oxide or potassium oxide, a higher acid receiving effect can be obtained, and contamination of the photoreceptor can be prevented more reliably.
The blending ratio of the acid acceptor is preferably 0.2 parts by mass or more, particularly 0.5 parts by mass or more, preferably 5 parts by mass or less, particularly 3 parts by mass or less, per 100 parts by mass of the total amount of rubber. preferable.
If the blending ratio is less than the above range, the above-described effect due to the inclusion of the acid acceptor may not be sufficiently obtained. On the other hand, if the above range is exceeded, the hardness of the roller body after crosslinking may increase.

Examples of the plasticizer include various plasticizers such as dibutyl phthalate (DBP), dioctyl phthalate (DOP), and tricresyl phosphate, and various waxes such as polar wax. Examples of the processing aid include fatty acids such as stearic acid.
The blending ratio of these plastic components is preferably 5 parts by mass or less per 100 parts by mass of the total amount of rubber. For example, this is to prevent the photosensitive member from being contaminated when it is attached to the image forming apparatus or during operation. In view of this object, it is particularly preferable to use a polar wax as the plastic component.

Examples of the deterioration preventing agent include various antiaging agents and antioxidants.
Of these, the antioxidant functions to reduce the environmental dependency of the roller resistance value of the transfer roller and to suppress an increase in the roller resistance value during continuous energization. Examples of the antioxidant include nickel diethyldithiocarbamate [NOCRACK (registered trademark) NEC-P manufactured by Ouchi Shinsei Chemical Co., Ltd.], nickel dibutyldithiocarbamate [NOCRACK NBC manufactured by Ouchi Shinsei Chemical Industrial Co., Ltd. ] Etc. are mentioned.

Examples of the filler include one or more of zinc oxide, silica, carbon, carbon black, clay, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, and the like.
By blending the filler, the mechanical strength of the roller body can be improved.
In addition, it is possible to impart electronic conductivity to the roller body by using conductive carbon black as a filler.

The blending ratio of the filler is preferably 5 parts by mass or more, preferably 50 parts by mass or less, particularly preferably 20 parts by mass or less, per 100 parts by mass of the total amount of rubber.
Examples of the scorch inhibitor include one or more of N-cyclohexylthiophthalimide, phthalic anhydride, N-nitrosodiphenylamine, 2,4-diphenyl-4-methyl-1-pentene, and the like. . N-cyclohexylthiophthalimide is particularly preferable.

The blending ratio of the scorch inhibitor is preferably 0.1 parts by mass or more per 100 parts by mass of the total amount of rubber, and is preferably 5 parts by mass or less, particularly preferably 1 part by mass or less.
The co-crosslinking agent refers to a component that itself has a function of crosslinking and also having a function of crosslinking the rubber component to polymerize the whole.
Examples of the co-crosslinking agent include methacrylic acid esters, ethylenically unsaturated monomers represented by metal salts of methacrylic acid or acrylic acid, and polyfunctional polymers using functional groups of 1,2-polybutadiene. 1 type, or 2 or more types, such as dioxime.

Among these, as the ethylenically unsaturated monomer, for example
(a) monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid,
(b) dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid,
(c) an ester or anhydride of the unsaturated carboxylic acid of (a) (b),
(d) the metal salt of (a) to (c),
(e) aliphatic conjugated dienes such as 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene,
(f) aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, ethylvinylbenzene, divinylbenzene,
(g) vinyl compounds having a heterocyclic ring such as triallyl isocyanurate, triallyl cyanurate, vinylpyridine,
(h) In addition, one or more kinds of vinyl cyanide compounds such as (meth) acrylonitrile or α-chloroacrylonitrile, acrolein, formylsterol, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone and the like can be mentioned.

Further, the ester of the unsaturated carboxylic acid (c) is preferably an ester of a monocarboxylic acid.
Examples of the esters of the monocarboxylic acids include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl ( (Meth) acrylate, n-pentyl (meth) acrylate, i-pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (Meth) acrylate, i-nonyl (meth) acrylate, tert-butylcyclohexyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate ( Alkyl esters of (meth) acrylic acid;
Aminoalkyl esters of (meth) acrylic acid such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, butylaminoethyl (meth) acrylate;
(Meth) acrylates having an aromatic ring such as benzyl (meth) acrylate, benzoyl (meth) acrylate, allyl (meth) acrylate;
(Meth) acrylates having an epoxy group such as glycidyl (meth) acrylate, metaglycidyl (meth) acrylate, and epoxycyclohexyl (meth) acrylate;
(Meth) acrylates having various functional groups such as N-methylol (meth) acrylamide, γ- (meth) acryloxypropyltrimethoxysilane, tetrahydrofurfuryl methacrylate;
Polyfunctional (meth) acrylates such as ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene dimethacrylate (EDMA), polyethylene glycol dimethacrylate, isobutylene ethylene dimethacrylate;
1 type, or 2 or more types, etc. are mentioned.

  The conductive rubber composition containing the above components can be prepared in the same manner as in the past. First, the rubber component is blended at a predetermined ratio and kneaded, and then the additives other than the foaming agent component and the crosslinking agent component are added and kneaded, and finally the foaming agent component and the crosslinking agent component are added and kneaded. A conductive rubber composition can be obtained. For the kneading, for example, a kneader, a Banbury mixer, an extruder or the like can be used.

<Image forming apparatus>
The conductive roller 19 of the present invention can be used by being incorporated in an image forming apparatus using electrophotography, such as a laser printer, an electrostatic copying machine, a plain paper facsimile machine, or a complex machine thereof. That is, among the image forming processes described above, the charging roller used in the charging process of the photosensitive member, the developing roller used in the developing process, the transfer roller used in the transferring process, and the cleaning roller used in the cleaning process can be incorporated in the image forming apparatus. it can. Thereby, the performance of the image forming apparatus can be stabilized more than before.

<Example 1>
(Preparation of conductive rubber composition)
As rubber, NBR [JSR N250SL manufactured by JSR Corporation, low nitrile NBR, acrylonitrile content: 20%] 80 parts by mass, EPDM [Esprene (registered trademark) EPDM505A manufactured by Sumitomo Chemical Co., Ltd.] 10 parts by mass, and 10 parts by mass of ECO [HYDRIN (registered trademark) T3108 manufactured by Nippon Zeon Co., Ltd.] was blended.
And each component shown in following Table 1 was mix | blended with 100 mass parts of said rubber | gum parts, and it knead | mixed for 3 to 5 minutes at 80 degreeC using the closed kneading machine, and prepared the rubber composition.

Each component in Table 1 is as follows.
Filler: Carbon black HAF
Foaming agent: ADCA-based foaming agent (trade name Binhore AC # 3 manufactured by Eiwa Chemical Industry Co., Ltd.)
Foaming aid: Urea-based foaming aid [trade name cell paste 101 manufactured by Eiwa Kasei Kogyo Co., Ltd.]
Acid acceptor: Hydrotalcite [DHT-4A-2 manufactured by Kyowa Chemical Industry Co., Ltd.]
Crosslinking agent: Powdered sulfur Accelerator DM: Di-2-benzothiazyl disulfide [Noxeller (registered trademark) DM manufactured by Ouchi Shinsei Chemical Co., Ltd.]
Accelerator TS: Tetramethylthiuram disulfide [Noxeller TS manufactured by Ouchi Shinsei Chemical Co., Ltd.]
(Manufacture of cylindrical foam rubber)
The conductive rubber composition is supplied to the extruder 3 of the manufacturing apparatus 1 shown in FIG. 1, and is extruded through the die 2 into a long cylindrical shape having an outer diameter of φ10.5 mm and an inner diameter of φ3.5 mm, and is extruded. While the cylindrical body 4 is continuously cut out without being cut and continuously passed through the continuous crosslinking apparatus 6 including the microwave crosslinking apparatus 8 and the hot-air crosslinking apparatus 9, After making it foam, it was made to cool continuously by letting cooling water pass, and the cylindrical foamed rubber 5 was manufactured.

  As shown in FIG. 2, the outer periphery 13 and the inner periphery 15 of the opening 11 are circular corresponding to the outer diameter and inner diameter of the cylindrical body 4, and the uppermost portion of the outer periphery 13 in the vertical direction. , And at the two lowermost positions, the planar shape of the front face 10 of the base 2 constituting the outer peripheral edge 13 is a substantially triangular shape with the tip pointed inward of the opening 11, and the inner side from the opening 11 of the base. A thing provided with the processus | protrusion 16 formed in the wedge shape which the width | variety and protrusion amount become small gradually toward the back was prepared. The protrusion 16 had a protrusion height of 1 mm inward in the radial direction and a base width of 1 mm.

Thereby, the continuous notch along the axial direction of the said cylindrical body 4 is carried out in the uppermost part of the perpendicular direction among the outer peripheral surfaces 12 of the cylindrical body 4 extruded through the said nozzle | cap | die 2, and the lowest two places. I put it in.
The output of the microwave crosslinking apparatus 8 was 6 kW, the control temperature in the tank was 160 ° C., the control temperature in the tank of the hot air crosslinking apparatus 9 was 250 ° C., the effective length of the heating tank was 8 m, and the line speed was 3 m / min.

The foamed and crosslinked tubular foamed rubber 5 had an outer diameter of approximately 15.0 mm and an inner diameter of approximately 4.0 mm.
(Preparation of conductive roller)
The cylindrical foam rubber is cut into a predetermined length to form a roller main body 21, and a metal having an outer diameter of φ5 mm (with a conductive thermosetting adhesive applied to the outer peripheral surface in the cylinder of the roller main body 21 ( SUM-24L) shaft 23 is press-fitted and heated in a hot air oven at 160 ° C. for 60 minutes to cure (secondary crosslinking) the thermosetting adhesive, thereby bringing the roller body 21 and the shaft 23 into contact with each other. Electrically joined and mechanically fixed.

Next, the outer peripheral surface 20 is traverse-ground using a cylindrical grinder to finish the outer diameter of the roller main body by φ12.0 mm (tolerance ± 0.1 mm), and both ends of the roller main body 21 are cut to form conductive rollers. Was made.
<Example 2>
As rubber, NBR [JSR N250SL, low nitrile NBR, acrylonitrile content: 20%] by 40 parts by mass, SBR [JSR 1502, JSR 1502, emulsion polymerization type, bound styrene: 23.5%] 40 parts by mass, 10 parts by mass of EPDM [Esprene (registered trademark) EPDM505A manufactured by Sumitomo Chemical Co., Ltd.], and 10 parts by mass of ECO [HYDRIN (registered trademark) T3108] manufactured by Nippon Zeon Co., Ltd.] A conductive rubber composition was prepared in the same manner as in Example 1, a cylindrical foam rubber was produced, and a conductive roller was produced.

<Example 3>
80 parts by mass of SBR [JSR1502 manufactured by JSR Corporation, emulsion polymerization type, bound styrene: 23.5%] as rubber, 10 parts by mass of EPDM [Esprene (registered trademark) EPDM505A manufactured by Sumitomo Chemical Co., Ltd.] A conductive rubber composition was prepared in the same manner as in Example 1 except that 10 parts by mass of ECO [HYDRIN (registered trademark) T3108 manufactured by Nippon Zeon Co., Ltd.] was blended to produce a cylindrical foam rubber. A neutral roller was produced.

<Examples 4 to 5>
As shown in FIG. 4, as the base 2, one having no protrusion 16 on the outer peripheral edge 13 is used, and the position in the vertical direction at a position 30 cm downstream from the opening 11 of the base 2 in the conveying direction of the tubular body 4 is used. Example except that a cutting edge 18 of a knife or a cutter is fixed to one uppermost position, and the cutting edge 18 is used to make a cut in the outer peripheral surface 12 of the tubular body 4 extruded from the base 2. A cylindrical foamed rubber was produced in the same manner as in 1 to 3, and a conductive roller was produced.

The penetration depth of the blade edge 18 from the outer peripheral surface 12 into the cylindrical body 4 was 1 mm.
<Comparative Examples 1-3>
As shown in FIG. 4, as the base 2, an outer peripheral edge 13 that does not have a protrusion 16 is used, and the cutting edge 18 or the like is not provided, so that the outer peripheral surface 12 is not cut. A cylindrical foamed rubber was produced in the same manner as in (3) to produce a conductive roller.

<Surface condition evaluation of cylindrical foam rubber>
A sample of 10 m was taken from the cylindrical foam rubber continuously produced in each of the above Examples and Comparative Examples, and the number of abnormal foams contained therein was counted.
The results are shown in Tables 2 and 3.

  From the results of Examples and Comparative Examples in Tables 2 and 3, cut the outer peripheral surface of the cylindrical body before the crosslinking and foaming at the same time as the cylindrical body is extruded or after extrusion. Thus, it has been found that the excess gas generated from the foaming agent during crosslinking and foaming and the foaming pressure caused thereby can be quickly and efficiently released outside the cylindrical body through the incision to prevent the occurrence of abnormal foaming.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Base 3 Extruder 4 Cylindrical body 5 Cylindrical foam rubber 6 Continuous bridge | crosslinking apparatus 7 Take-out machine 8 Microwave bridge | crosslinking apparatus 9 Hot-air bridge | crosslinking apparatus 10 Front surface 11 Opening 12 Outer peripheral surface 13 Outer peripheral edge 14 Inner peripheral surface 15 Inner peripheral edge 16 Protrusion 17 Cutting 18 Cutting edge 19 Conductive roller 20 Outer peripheral surface 21 Roller body 22 Through hole 23 Shaft

Claims (6)

  A production method for producing a tubular foamed rubber by continuously crosslinking and foaming a rubber composition containing a foaming agent while extruding it into a tubular shape through a die of an extruder, comprising: The process of making continuous cuts along the axial direction of the cylindrical body on the outer peripheral surface of the cylindrical body at the same time as the extrusion of the cylindrical body or after extrusion and before crosslinking and foaming The manufacturing method of the cylindrical foam rubber characterized by including.   Protrusions projecting inwardly from the outer peripheral edge are provided on the outer peripheral edge of the opening of the base, and along the axial direction of the cylindrical body on the outer peripheral surface of the cylindrical body extruded through the base by the protrusion. The method for producing cylindrical foamed rubber according to claim 1, wherein continuous incisions are made.   A continuous incision along the axial direction of the cylindrical body is made by using a cutting edge or a needle tip fixed in the vicinity of the die on the outer peripheral surface of the cylindrical body before the crosslinking and foaming after extrusion molding. A method for producing the cylindrical foamed rubber according to 1.   The cylindrical body is continuously cross-linked and foamed while being transported along a substantially horizontal direction, and in the transported state, at least one of the outer peripheral surfaces of the cylindrical body located above the vertical direction, The manufacturing method of the cylindrical foam rubber of any one of Claim 1 thru | or 3 which makes the continuous cut along the axial direction of a cylindrical body.   A conductive roller composition comprising a cylindrical roller body made of a cylindrical foamed rubber manufactured by the manufacturing method according to any one of claims 1 to 4 using a conductive rubber composition. roller.   An image forming apparatus comprising the conductive roller according to claim 5.

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