JP2017072156A - Method of manufacturing semiconductive roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method that enables a semiconductive roller to be manufactured with higher productivity than now by eliminating a step of inserting a temporary core causing a trouble.SOLUTION: An uncrosslinked cylindrical body 13, from which a semiconductive roller is made, is crosslinked by being heated within a vulcanizer in the state of being housed in a linear storage groove 8 making a cross-section of an inner bottom surface 7 assume a concavely-curved shape like an arc with a diameter R1.05-2.6 times larger than a diameter Rof the cylindrical body.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a semiconductive roller used by being incorporated in an image forming apparatus using, for example, electrophotography.

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, an image is formed on the surface of a sheet through the following steps. The
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 photoreceptor in a state where the toner is 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, after the toner image is transferred onto the surface of the paper (transfer process), and further fixed (fixing process), 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 first transferred to the surface of the image carrier (primary transfer step) without being directly transferred to the surface of the paper, and then the image carrier In some cases, retransfer is performed from the front side to the front side of the paper (secondary transfer process).
Thereafter, the toner remaining on the surface of the photoconductor after the transfer is removed (cleaning step), thereby completing a series of image formation.

Among the above processes, the charging process, the developing process, the transfer process (including the primary and secondary transfer processes), and the cleaning process of the photosensitive member include a semiconductive roller provided with a semiconductivity according to each application. Used.
Such a semiconductive roller is formed by, for example, extruding a rubber composition having semiconductivity and crosslinkability into a cylindrical shape through a head of an extruder, and then cutting it into a predetermined length to form a cylindrical body. It is manufactured by heating and crosslinking a cylindrical body in a vulcanizing can. A cored bar is inserted into the central through hole after crosslinking.

  In addition, when bridging, a bridging temporary core is inserted into the through hole to correct the curve and deformation generated in the cylindrical body at the time of extrusion molding, and to prevent the curve from becoming large at the time of crosslinking. The tubular body is held in a hollow state by suspending the temporary core from the vulcanizing can tray so that the tubular body at the time of crosslinking is not partially deformed by contacting with other members in the vulcanizing can. In general, after the tray is accommodated in a vulcanizing can and crosslinked, the temporary core is reattached to an actual core (Patent Document 1, etc.).

Japanese Patent Laid-Open No. 2015-7668

Automation of the temporary core insertion process is widely used in order to improve the productivity of the semiconductive roller.
That is, with the cylindrical bodies cut to a predetermined length one by one sandwiched between a pair of receiving frames, the temporary core is inserted into the through-hole from one opening of the fixed cylindrical body. Devices have been developed and put into practical use that automatically perform the operation to be performed by the operation of a cylinder or the like.

However, for the sake of safety, for example, due to the difference in dimensions of individual cylindrical bodies or the displacement when opening and closing the receiving frame, the through hole of the cylindrical body held by the receiving frame and the center position of the core metal are shifted. Troubles such as the automatic stop of the apparatus occur frequently, which is one of the reasons why the productivity of the semiconductive roller cannot be improved as compared with the current situation.
An object of the present invention is to provide a manufacturing method capable of manufacturing a semiconductive roller with a higher productivity than the current state without a temporary core insertion process causing trouble.

  According to the present invention, a rubber composition having semiconductivity and crosslinkability is extruded through a head of an extruder into a cylinder having a predetermined radius, and then cut into a predetermined length to form a cylindrical body. The cross-sectional shape of the inner bottom surface is an arc-shaped concave curved surface having a radius not less than 1.05 times and not more than 2.6 times the radius of the cylindrical body, and not less than the total length after cutting of the cylindrical body A method for producing a semiconductive roller, comprising a step of heating and crosslinking in a vulcanizing can in a state of being accommodated in a linear accommodation groove having a length of 5 mm.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method which can eliminate the temporary core insertion process which causes a trouble, and can manufacture a semiconductive roller with productivity higher than the present condition can be provided.

Fig. (A) is a perspective view for explaining the outline of a tray for a vulcanization can used in an example of an embodiment of the production method of the present invention, and Fig. (B) is an enlarged view of a main part of the tray. FIG. It is a perspective view which shows an example of the semiconductive roller manufactured with the manufacturing method of the said example. It is a figure explaining the method to measure the roller resistance value of a semiconductive roller.

  According to the present invention, a rubber composition having semiconductivity and crosslinkability is extruded through a head of an extruder into a cylinder having a predetermined radius, and then cut into a predetermined length to form a cylindrical body. The cross-sectional shape of the inner bottom surface is an arc-shaped concave curved surface having a radius not less than 1.05 times and not more than 2.6 times the radius of the cylindrical body, and not less than the total length after cutting of the cylindrical body A method for producing a semiconductive roller, comprising a step of heating and crosslinking in a vulcanizing can in a state of being accommodated in a linear accommodation groove having a length of 5 mm.

According to the present invention, the tubular body before cross-linking that has been extruded and cut to a predetermined length is accommodated in the housing groove to correct the curvature, and the curving is prevented from becoming large during the cross-linking. By storing in a sulfur can and heating, it is possible to crosslink in a good state without deformation or bending, which is equivalent to the conventional case of crosslinking in a hollow state.
This is because the cross-sectional shape of the inner bottom surface of the housing groove is an arc-shaped concave curved surface along the outer peripheral surface of the cylindrical body as described above, and the radius is set in the above range.

That is, when the radius of the inner bottom surface of the housing groove is less than 1.05 times the radius of the cylindrical body, the contact portion between the inner bottom surface and the outer peripheral surface of the cylindrical body increases. It becomes easy to produce a dent.
The resulting dents remain unresolved by subsequent polishing, or even if the dents are eliminated, the roller resistance value may become uneven due to non-uniform internal structure where the original dents were. Cause problems.

On the other hand, when the radius of the inner bottom surface of the accommodation groove exceeds 2.6 times the radius of the cylindrical body, the gap between the accommodation groove and the cylindrical body is too large, and the cylinder before bridging is formed in the accommodation groove. When the cylindrical body is accommodated, it is not possible to sufficiently correct the curvature of the cylindrical body, or it is not possible to sufficiently suppress the increase of the curvature at the time of crosslinking. There is a tendency to become too much.
And even if the cored bar is inserted into the through hole in the subsequent process, even if the curved surface of the cylindrical body cannot be sufficiently corrected and a polishing residue is generated on the outer peripheral surface, or the curvature can be sufficiently corrected, Due to the non-uniformity of the generated internal structure, there arises a problem that the roller resistance value is uneven.

In addition, when the radius of the inner bottom surface of the receiving groove exceeds 2.6 times the radius of the cylindrical body, the difference between the radius of curvature of the outer peripheral surface of the cylindrical body and the radius of curvature of the inner bottom surface of the receiving groove is large. It becomes too much and it becomes easy to produce the big dent along the inner bottom face of an accommodation groove in the cylindrical body at the time of bridge | crosslinking.
On the other hand, by setting the radius of the inner bottom surface of the receiving groove to be 10.5 times or more and 2.6 times or less of the radius of the cylindrical body, the cylindrical body at the time of crosslinking is dented or curved. It can be suppressed as much as possible.

Therefore, it is possible to crosslink the cylindrical body in a good state without deformation or bending, equivalent to the conventional case where it is cross-linked while being held in a hollow state. Without it, it becomes possible to manufacture a semiconductive roller with higher productivity than the present situation.
<Method of manufacturing semiconductive roller>
FIG. 1 (a) is a perspective view for explaining the outline of a tray for a vulcanizing can used in an example of an embodiment of the production method of the present invention, and FIG. 1 (b) is an enlarged view of a main part of the tray. It is an end elevation shown.

FIG. 2 is a perspective view showing an example of a semiconductive roller manufactured by the manufacturing method of the above example.
Referring to FIG. 2, the semiconductive roller 1 of this example is formed of a non-porous and single-layered cylinder by a rubber composition having semiconductivity and crosslinkability, and the center of the roller 1 The shaft 3 is inserted into the hole 2 and fixed.

The shaft 3 is integrally formed of a metal such as iron, aluminum, an aluminum alloy, or stainless steel.
The shaft 3 is electrically fixed to the semiconductive roller 1 via, for example, a conductive adhesive and is mechanically fixed, or has an outer diameter larger than the inner diameter of the through hole 2. By press-fitting into the through-hole 2, it is electrically joined to the semiconductive roller 1 and is mechanically fixed and rotated integrally.

An oxide film 5 may be formed on the outer peripheral surface 4 of the semiconductive roller 1 as shown in an enlarged manner in FIG.
When the oxide film 5 is formed, the oxide film 5 functions as a dielectric layer, and the dielectric loss tangent of the semiconductive roller 1 can be reduced.
For example, when the semiconductive roller 1 is used as a charging roller, the oxide film 5 functions as a low friction layer, and adhesion and accumulation of external additives and the like can be further suppressed.

In addition, since the oxide film 5 can be easily formed, for example, by simply irradiating ultraviolet rays in an oxidizing atmosphere, it is possible to suppress the productivity of the semiconductive roller 1 from being lowered and the manufacturing cost from being increased. However, the oxide film 5 may not be formed.
1 (a) and 1 (b), a tray 6 used in the manufacturing method of this example has a linear shape in which the cross-sectional shape of the inner bottom surface 7 in the direction orthogonal to the length direction is an arc-shaped concave curved surface. A plurality of the receiving grooves 8 (28 in the figure) are arranged in parallel to each other.

For example in the figure, each receiving groove 8, an iron plate or the like, is configured as an inner surface of a substantially semi-cylindrical body 9 which radius R ₁ is formed by processing such as bending to be constant in the inner bottom surface 7 Yes.
In a state where the plurality of substantially half-cylindrical bodies 9 are bridged between a pair of frame bodies 10 arranged in parallel to each other so that the length direction is orthogonal to the length direction of the frame body 10, the frame body 10. In contrast, the substantially semi-cylindrical trays 6 are configured by fixing the adjacent substantially half-cylindrical bodies 9 to each other by welding or the like.

Further, a rod that can be used as a handle when the tray 6 is inserted into and removed from a vulcanizing can (not shown) is defined between both ends of the pair of frame bodies 10 while defining the interval between the pair of frame bodies 10. 11 is fixed in a state of being bridged.
In FIG. 1A, reference numeral 12 denotes a guide for placing and sliding the tray 6 on a rail in the vulcanizing can when the tray 6 is taken in and out of the vulcanizing can.

As described above, the radius R ₁ of the inner bottom surface 7 of the housing groove 8 that is the inner surface of the substantially semi-cylindrical body 9 is the precursor of the semiconductive roller 1 that is housed in the housing groove 8 and crosslinked in the vulcanizing can. as cylindrical body 13 radius _{R 2} of 1.05 times or more of the body, it is necessary that 2.6 times or less. The reason for this is as described above.
In consideration of further improving the above-described effect, the radius R ₁ of the inner bottom surface 7 of the receiving groove 8 is preferably 1.09 times or more the radius R ₂ of the cylindrical body 13 even in the above range. It is preferably 1.82 times or less.

More specifically, for example, when the cylindrical body 13 having a diameter of 16.5 mm and a radius R ₂ of 8.25 mm is cross-linked, the radius R ₁ of the inner bottom surface 7 of the receiving groove 8 is 8.7 mm or more, particularly 9 mm. Preferably, it is 21.4 mm or less, particularly 15 mm or less.
Further, for example, the receiving groove 8 in which the radius R ₁ of the inner bottom surface 7 is 11.5 mm is a cylindrical shape having various radii with a radius R ₂ of 4.5 mm or more and 10.9 mm or less, particularly 10 mm or less. It can be used to crosslink the body 13.

The length of the receiving groove 8, i.e. the length L ₁ of substantially semi-cylindrical body 9 in this example, the overall length after cutting of the tubular body 13 to be accommodated in the receiving groove 8 is cross-linked in a vulcanizer Although it may be L ₂ or more, in consideration of expansion of the cylindrical body 13 at the time of crosslinking, it is particularly preferably 1.1 times or more of the total length L ₂ .
However, when the length L ₁ of the receiving groove 8 of the total length L ₂ of the cylindrical body 13 is too long, the size and capacity of the vulcanizer of the tray 6 becomes excessively large, the processing efficiency of the tubular body 13 Therefore, the length L ₁ of the housing groove 8 is preferably about 1.4 times or less of the total length L ₂ of the cylindrical body 13.

However, depending on the balance between the total length L ₂ of the cylindrical body 13 and the capacity of the vulcanizing can to be used and the size of the tray 6, for example, two or more cylindrical bodies 13 are disposed in the longitudinal direction in one receiving groove 8. Tile be crosslinked housing is also possible, in which case, the upper limit of the length L ₁ of the receiving groove 8 is not limited to the above.
In the manufacturing method of this example using the tray 6, the rubber composition having semiconductivity and crosslinkability is first prepared, and the rubber composition is extruded through a head of an extruder into a cylinder having a predetermined radius. A plurality of cylindrical bodies 13 are produced by repeating the process of cutting to a predetermined length.

The plurality of cylindrical bodies 13 are accommodated in the accommodating grooves 8 on the tray 6 and are heated and crosslinked in a vulcanizing can. The conditions for crosslinking may be the same as in the prior art.
Both the operation of housing the cylindrical body 13 in the housing groove 8 and the operation of taking out the crosslinked tubular body 13 from the housing groove 8 are easy to automate, and these operations are the conventional cylindrical body. Positioning such as the operation of inserting the temporary core into the thirteen through holes is unnecessary, and even if it is automated, there is no possibility of frequent troubles such as the automatic stop of the apparatus.

Therefore, by cross-linking the cylindrical body 13 using the tray 6, the semiconductive roller 1 can be manufactured with a higher productivity than the current state without a temporary core insertion process causing trouble.
The steps after the cross-linking can be carried out in the same manner as before.
That is, the cross-linked cylindrical body 13 is secondarily cross-linked by heating using an oven or the like, cooled, cut to a predetermined length and polished to a predetermined outer diameter, as shown in FIG. The semiconductive roller 1 is produced.

The shaft 3 can be inserted through the through-hole 2 and fixed at any time from cross-linking to after polishing.
However, after crosslinking, it is preferable to first perform secondary crosslinking to polishing in a state where the shaft 3 is inserted into the through hole 2. Thereby, the curvature and deformation | transformation of the semiconductive roller 1 by the expansion / contraction at the time of secondary bridge | crosslinking can be prevented. Further, by polishing while rotating about the shaft 3, the workability of the polishing can be improved, and the flare of the outer peripheral surface 4 can be suppressed.

As described above, the shaft 3 is either press-fitted into the through-hole 2 having an outer diameter larger than the inner diameter of the through-hole 2 or through a thermosetting adhesive having conductivity before the secondary crosslinking. What is necessary is just to penetrate the cylindrical body.
In the latter case, the thermosetting adhesive is cured at the same time as the semiconductive roller 1 is secondarily crosslinked by heating in the oven, and the shaft 3 is electrically joined to the cylindrical body. Fixed mechanically.

In the former case, electrical joining and mechanical fixing are completed simultaneously with press-fitting.
Subsequently, the semiconductive roller 1 of the said example is manufactured by forming the oxide film 5 as needed in the outer peripheral surface 4 after grinding | polishing.
As described above, the oxide film 5 is preferably formed by irradiating the outer peripheral surface 4 of the semiconductive roller 1 with ultraviolet rays because the oxide film 5 can be formed easily and efficiently. That is, the oxide film 5 is formed by oxidizing the rubber composition itself constituting the outer peripheral surface 4 of the semiconductive roller 1 by irradiating with ultraviolet rays having a predetermined wavelength for a predetermined time in an oxidizing atmosphere.

Moreover, the oxide film 5 is formed by oxidizing the rubber composition itself constituting the outer peripheral surface 4 of the semiconductive roller 1 by irradiation with ultraviolet rays as described above. Thus, there is no problem as in the coated layer, and the thickness and surface shape are excellent in uniformity.
In consideration of efficiently oxidizing the rubber composition to form the oxide film 5, the wavelength of the ultraviolet rays to be irradiated is preferably 100 nm or more, preferably 400 nm or less, particularly preferably 300 nm or less. The irradiation time is preferably 30 seconds or more, particularly preferably 1 minute or more, and is preferably 30 minutes or less, particularly preferably 20 minutes or less.

However, the oxide film 5 may be formed by other methods such as ozone exposure, or may be omitted as described above.
<Rubber composition>
As the rubber composition used as the basis of the semiconductive roller 1, various rubber compositions having semiconductive and crosslinkability can be used.

In the following, an example of a rubber composition imparted with ion conductivity by including epichlorohydrin rubber, which is an ion conductive rubber, as a rubber component is shown, but the composition of the rubber composition is not necessarily limited thereto. .
<Epichlorohydrin rubber>
Among the rubber components, as the epichlorohydrin rubber, various polymers containing epichlorohydrin as a repeating unit and having ionic conductivity can be used.

  Examples of such epichlorohydrin rubber include epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide binary copolymer (ECO), epichlorohydrin-propylene oxide binary copolymer, epichlorohydrin-allyl glycidyl ether binary copolymer, epichlorohydrin-ethylene oxide. 1 type or 2 types of allyl glycidyl ether terpolymer (GECO), epichlorohydrin-propylene oxide-allyl glycidyl ether ternary copolymer, epichlorohydrin-ethylene oxide-propylene oxide-allyl glycidyl ether quaternary copolymer, etc. The above is mentioned.

Among them, a copolymer containing ethylene oxide, particularly ECO and / or GECO is preferable.
The ethylene oxide content in both copolymers 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 semiconductive roller. However, when the ethylene oxide content is less than this range, such a function cannot be obtained sufficiently, so that the roller resistance value 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 segment motion of the molecular chain is hindered, so that the roller resistance value tends to increase. In addition, the semiconductive roller after crosslinking may become too hard, or the viscosity of the rubber composition before crosslinking may increase when heated and melted, resulting in decreased processability.
The epichlorohydrin content in ECO is the remaining amount of 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 semiconductive roller. However, when the allyl glycidyl ether content is less than this range, such a function cannot be obtained, so that the roller resistance value may not be sufficiently reduced.

On the other hand, since allyl glycidyl ether functions as a crosslinking point during GECO crosslinking, when the allyl glycidyl ether content exceeds the above range, the GECO crosslinking density becomes too high, preventing the molecular chain segment movement. On the other hand, the roller resistance value tends to increase.
The epichlorohydrin content in GECO is the remaining amount of ethylene oxide content and allyl glycidyl ether content. That is, the epichlorohydrin content is preferably 10 mol% or more, more preferably 15 mol% or more, and preferably 69.5 mol% or less, particularly 48 mol% or less.

As GECO, in addition to the above-described copolymer in the narrow sense obtained by copolymerization of the three types of monomers, a modification obtained by modifying epichlorohydrin-ethylene oxide copolymer (ECO) with allyl glycidyl ether. Things are also known, and such modified products can also be used as GECO.
The blending ratio of epichlorohydrin rubber is preferably 15 parts by mass or more, particularly 50 parts by mass or more, in the total amount of 100 parts by mass of rubber in the case of a charging roller in the combination system with diene rubber described below. It is preferably 80 parts by mass or less, particularly 70 parts by mass or less. Further, in the developing roller, it is preferably 5 parts by mass or more, particularly 10 parts by mass or more, preferably 50 parts by mass or less, particularly 30 parts by mass or less, in 100 parts by mass of the total rubber content.

<Diene rubber>
As the rubber component, a diene rubber may be used in combination with the epichlorohydrin rubber.
The diene rubber improves the mechanical strength and durability of the semiconductive roller 1 or has a characteristic as a rubber for the semiconductive roller 1, that is, a characteristic that is flexible and has a small compression set and hardly causes settling. And so on.

Further, it is mainly diene rubber that is oxidized when the outer peripheral surface 4 of the semiconductive roller 1 is irradiated with ultraviolet rays to form an oxide film 5 on the outer peripheral surface 4.
Examples of the diene rubber include at least selected from the group consisting of styrene butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), butadiene rubber (BR), natural rubber, and isoprene rubber (IR). One type is mentioned.

<Crosslinking component>
The crosslinking component mainly includes a thiourea-based crosslinking agent for crosslinking epichlorohydrin rubber, a diene rubber, or a sulfur-based crosslinking agent for crosslinking GECO, etc. of epichlorohydrin rubber, and an accelerator for both crosslinking agents. It is preferable to use together.
(Thiourea crosslinking agent and accelerator)
As the thiourea-based crosslinking agent, various compounds having a thiourea group in the molecule and mainly functioning as a crosslinking agent for epichlorohydrin rubber can be used.

Examples of the thiourea-based crosslinking agent include tetramethylthiourea, trimethylthiourea, ethylenethiourea (also known as 2-mercaptoimidazoline), formula (1):
(C _n H _{2n + 1} NH) ₂ C = S (1)
[In formula, n shows the integer of 1-10. ] 1 type (s) or 2 or more types, such as thiourea represented by these. In particular, ethylene thiourea is preferable.

The blending ratio of the thiourea-based crosslinking agent is preferably 0.3 parts by mass or more and preferably 1 part by mass or less per 100 parts by mass of the total amount of rubber.
Examples of accelerators for thiourea crosslinking agents include guanidine accelerators such as 1,3-diphenylguanidine (D), 1,3-di-o-tolylguanidine (DT), and 1-o-tolylbiguanide (BG). 1 type or 2 types or more, such as an agent, is mentioned. In particular, 1,3-di-o-tolylguanidine (DT) is preferable.

The blending ratio of the accelerator is preferably 0.3 parts by mass or more per 100 parts by mass of the total amount of rubber, and is preferably 1 part by mass or less.
(Sulfur-based crosslinking agent and accelerator)
As the sulfur-based crosslinking agent, at least one selected from the group consisting of sulfur and sulfur-containing crosslinking agents is used.

Among these, as the sulfur-containing crosslinking agent, various organic compounds that contain sulfur in the molecule and can function as a crosslinking agent for diene rubber or GECO can be used. Examples of the sulfur-containing crosslinking agent include 4,4′-dithiodimorpholine (R).
However, sulfur is particularly preferable as the sulfur-based crosslinking agent.
The blending ratio of sulfur is preferably 1 part by mass or more and preferably 2 parts by mass or less per 100 parts by mass of the total amount of rubber.

When a sulfur-containing crosslinking agent is used as the crosslinking agent, the blending ratio is adjusted so that the mass part of the sulfur contained in the molecule per 100 parts by mass of the total rubber content falls within the above range. preferable.
Examples of accelerators for sulfur-based crosslinking agents include sulfur-containing accelerators containing sulfur in the molecule, such as thiazole accelerators, thiuram accelerators, sulfenamide accelerators, and dithiocarbamate accelerators. 1 type or 2 types or more are mentioned.

Of these, it is preferable to use a thiazole accelerator and a thiuram accelerator in combination.
Examples of the thiazole accelerator include 2-mercaptobenzothiazole (M), di-2-benzothiazolyl disulfide (DM), zinc salt of 2-mercaptobenzothiazole (MZ), and cyclohexylamine of 2-mercaptobenzothiazole. 1 type or 2 types of salt (HM, M60-OT), 2- (N, N-diethylthiocarbamoylthio) benzothiazole (64), 2- (4'-morpholinodithio) benzothiazole (DS, MDB), etc. The above is mentioned. In particular, di-2-benzothiazolyl disulfide (DM) is preferable.

  Examples of the thiuram accelerator include tetramethylthiuram monosulfide (TS), tetramethylthiuram disulfide (TT, TMT), tetraethylthiuram disulfide (TET), tetrabutylthiuram disulfide (TBT), tetrakis (2-ethylhexyl) thiuram. One type or two or more types such as disulfide (TOT-N) and dipentamethylene thiuram tetrasulfide (TRA) can be used. Tetramethylthiuram monosulfide (TS) is particularly preferable.

In the combined system of the two sulfur-containing accelerators, the blending ratio of the thiazole accelerator is preferably 1 part by mass or more and 2 parts by mass or less per 100 parts by mass of the total amount of rubber. The blending ratio of the thiuram accelerator is preferably 0.3 parts by weight or more and 1 part by weight or less per 100 parts by weight of the total amount of rubber.
<Ion salt>
The rubber composition preferably further contains a salt (ionic salt) of an anion having a fluoro group and a sulfonyl group and a cation in the molecule.

By including such an ionic salt, better semiconductivity can be imparted to the semiconductive roller.
Examples of the anion having a fluoro group and a sulfonyl group in the molecule constituting the ionic salt include one or two of fluoroalkylsulfonic acid ion, bis (fluoroalkylsulfonyl) imide ion, tris (fluoroalkylsulfonyl) methide ion, etc. The above is mentioned.

Of these, examples of the fluoroalkylsulfonic acid ion include one or more of CF ₃ SO ₃ ^— , C ₄ F ₉ SO ₃ ^{—, and the} like.
Examples of bis (fluoroalkylsulfonyl) imide ions include (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (C ₄ F ₉ SO ₂ ) (CF ₃ SO ₂ ) N ^−. , (FSO ₂ C ₆ F ₄ ) (CF ₃ SO ₂ ) N ⁻ , (C ₈ F ₁₇ SO ₂ ) (CF ₃ SO ₂ ) N ⁻ , (CF ₃ CH ₂ OSO ₂ ) ₂ N ⁻ , (CF _{3 CF 2 CH 2 OSO 2) 2} N -, (HCF 2 CF 2 CH 2 OSO 2) 2 N - include one or more of such ^{_{-, [(CF 3) 2}} CHOSO 2] 2 N.

Further, examples of the tris (fluoroalkylsulfonyl) methide ion include one or more of (CF ₃ SO ₂ ) ₃ C ⁻ , (CF ₃ CH ₂ OSO ₂ ) ₃ C ^{− and the} like.
Examples of the cation include ions of alkali metals such as sodium, lithium and potassium, ions of group 2 elements such as beryllium, magnesium, calcium, strontium and barium, ions of transition elements, cations of amphoteric elements, One kind or two or more kinds such as a quaternary ammonium ion and an imidazolium cation may be mentioned.

As the ionic salt, a lithium salt using lithium ion as a cation and a potassium salt using potassium ion as a cation are particularly preferable.
Among them, (CF ₃ SO ₂ ) ₂ NLi [lithium bis (trifluoromethanesulfonyl) imide], and in terms of the effect of improving the ionic conductivity of the rubber composition and reducing the roller resistance value of the semiconductive roller, / Or (CF ₃ SO ₂ ) ₂ NK [potassium bis (trifluoromethanesulfonyl) imide] is preferred.

The blending ratio of the ionic salt is preferably 0.5 parts by mass or more, particularly 0.8 parts by mass or more, preferably 5 parts by mass or less, particularly 4 parts by mass or less, per 100 parts by mass of the total amount of rubber. .
If the blending ratio of the ionic salt is less than this range, the effect of reducing the roller resistance value by improving the ionic conductivity of the semiconductive roller may not be obtained.

On the other hand, not only the effect beyond that range is not obtained, but also the excessive ionic salt blooms on the outer peripheral surface of the semiconductive roller to contaminate the photoconductor, or the oxide film due to ultraviolet irradiation etc. May interfere with formation.
<Others>
You may mix | blend various additives with a rubber composition further as needed. Examples of additives include acceleration aids, acid acceptors, plasticizers, processing aids, deterioration inhibitors, fillers, scorch prevention agents, lubricants, pigments, antistatic agents, flame retardants, neutralizing agents, and nucleating agents. And a co-crosslinking agent.

Among these, examples of the acceleration aid include metal compounds such as zinc white; 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 is preferably 3 parts by mass or more and preferably 7 parts by mass or less per 100 parts by mass of the total amount of rubber.

The acid acceptor prevents chlorine-based gas generated from epichlorohydrin rubber or CR from remaining in the semiconductive roller during crosslinking of the rubber component, thereby preventing crosslinking inhibition or contamination of the photoreceptor. To work.
As the acid acceptor, various substances acting as an acid acceptor can be used. Among them, hydrotalcite or magsarat having excellent dispersibility is preferable, and hydrotalcite is particularly preferable.

In addition, when 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 even better.
The blending ratio of the acid acceptor is preferably 3 parts by mass or more and preferably 7 parts by mass or less per 100 parts by mass of the total amount of rubber.
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 acid metal salts such as zinc stearate.

The blending ratio of the plasticizer and / or processing aid is preferably 3 parts by mass or less per 100 parts by mass of the total amount of rubber.
Examples of the deterioration preventing agent include various antiaging agents and antioxidants.
Among these, the anti-aging agent functions to reduce the environmental dependency of the roller resistance value of the semiconductive roller and to suppress an increase in the roller resistance value during continuous energization. As an anti-aging agent, for example, nickel diethyldithiocarbamate [Nocrac (registered trademark) NEC-P manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.], nickel dibutyldithiocarbamate [Nocrack NBC manufactured by Ouchi Shinsei Chemical Industrial Co., Ltd.] Etc.

The blending ratio of the antioxidant is preferably 0.3 parts by mass or more and 1 part by mass or less per 100 parts by mass of the total amount of rubber.
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 semiconductive roller can be improved.
The blending ratio of the filler is preferably 5 parts by mass or more and preferably 20 parts by mass or less per 100 parts by mass of the total amount of rubber.
Further, a conductive filler such as conductive carbon black may be blended as a filler to impart electronic conductivity to the semiconductive roller.

Examples of the conductive carbon black include acetylene black.
The blending ratio of conductive carbon black is preferably 1 part by mass or more and preferably 5 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 and preferably 1 part by mass or less per 100 parts by mass of the total amount of rubber.
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 co-crosslinking agents include methacrylic acid esters, or ethylenically unsaturated monomers represented by metal salts of methacrylic acid or acrylic acid, polyfunctional polymers using functional groups of 1,2-polybutadiene, Or 1 type, or 2 or more types, such as dioxime, is mentioned.

Among these, examples of the ethylenically unsaturated monomer include one or more of compounds represented by the following (a) to (h).
(a) Monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid.
(b) Dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid.
(c) Esters or anhydrides of unsaturated carboxylic acids of (a) (b).

(d) Metal salts of (a) to (c).
(e) Aliphatic conjugated dienes such as 1,3-butadiene, isoprene and 2-chloro-1,3-butadiene.
(f) Aromatic vinyl compounds such as styrene, α-methylstyrene, vinyl toluene, ethyl vinyl benzene and divinyl benzene.

(g) Vinyl compounds having a heterocyclic ring, such as triallyl isocyanurate, triallyl cyanurate, and vinylpyridine.
(h) Other vinyl cyanide compounds such as (meth) acrylonitrile or α-chloroacrylonitrile, acrolein, formylsterol, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone.

The ester of unsaturated carboxylic acids (c) is preferably an ester of monocarboxylic acids.
Examples of the esters of monocarboxylic acids include one or more of the following various compounds.
Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, n-pentyl (meta ) Acrylate, i-pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, i-nonyl (meth) ), Tert-butylcyclohexyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, and other alkyl esters of (meth) acrylic acid.

Aminoalkyl esters of (meth) acrylic acid, such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and butylaminoethyl (meth) acrylate.
(Meth) acrylates having an aromatic ring, such as benzyl (meth) acrylate, benzoyl (meth) acrylate, and allyl (meth) acrylate.

(Meth) acrylates having an epoxy group, such as glycidyl (meth) acrylate, metaglycidyl (meth) acrylate, and epoxycyclohexyl (meth) acrylate.
(Meth) acrylate having various functional groups such as N-methylol (meth) acrylamide, γ- (meth) acryloxypropyltrimethoxysilane, and tetrahydrofurfuryl methacrylate.

Polyfunctional (meth) acrylates such as ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene dimethacrylate (EDMA), polyethylene glycol dimethacrylate, and isobutylene ethylene dimethacrylate.
The rubber composition containing each component demonstrated above can be prepared similarly to the past. First, the rubber component is blended at a predetermined ratio and kneaded, then the ionic salt and various additives other than the crosslinking component are added and kneaded, and finally the rubber composition is added and kneaded by adding the crosslinking component. can get. For kneading, for example, a closed kneader such as an intermix, a Banbury mixer, a kneader, an extruder, or an open roll can be used.

<Semiconductive roller 1>
The radius R ₂ , hardness, roller resistance value, and the like of the semiconductive roller 1 manufactured through the above-described steps can be set in an arbitrary range depending on the structure and application.
For example, as described above, the non-porous single-layer semiconductive roller 1 used as a charging roller preferably has a diameter of 8 mm (radius R ₂ : 4 mm) or more, and 15 mm (radius R ₂ : 7. 5 mm) or less. The Shore A hardness is preferably 55 ° or more, and preferably 65 ° or less. Furthermore, the roller resistance value is preferably 1 × 10 ⁵ Ω or more, and preferably 1 × 10 ⁶ Ω or less.

The non-porous single-layer semiconductive roller 1 used as a developing roller preferably has a diameter of 10 mm (radius R ₂ : 5 mm) or more, and 17 mm (radius R ₂ : 8.5 mm) or less. Preferably there is. The Shore A hardness is preferably 40 ° or more, and preferably 50 ° or less. Further, the roller resistance value is preferably 1 × 10 ⁶ Ω or more, and preferably 1 × 10 ⁷ Ω or less.

In the present invention, the Shore A hardness is measured according to the measurement method described in Japanese Industrial Standard JIS K6253-3-3 _{: 2012 under} the condition of a temperature of 23 ± 2 ° C., a micro rubber hardness meter MD manufactured by Kobunshi Keiki Co., Ltd. It shall be expressed by a value measured using -1.
The roller resistance value of the semiconductive roller 1 is expressed by a value measured by the following method. The roller resistance value is a roller resistance value in a state where the oxide film 5 is formed when the oxide film 5 is formed on the outer peripheral surface 4 of the semiconductive roller 1.

When the semiconductive roller 1 is non-porous and formed in a single layer as described above, the structure can be simplified and the durability and the like can be improved.
If the semiconductive roller 1 is non-porous, the cylindrical body 13 is deformed when the cylindrical body 13 that is the basis of the semiconductive roller 1 is cross-linked in the state of being accommodated in the accommodation groove 8. Can be suppressed even better.

The single layer means that the number of rubber layers is a single layer, and the oxide film 5 is not included in the number of layers.
In order to adjust the above-described characteristics of the semiconductive roller 1, for example, the type and combination of the rubber component, the crosslinking agent, or other additives constituting the rubber composition, or the blending ratio may be adjusted. .

<Roller resistance value measurement>
FIG. 3 is a diagram illustrating a method for measuring the roller resistance value of the semiconductive roller 1.
2 and 3, in the present invention, the roller resistance value R (Ω) of the semiconductive roller 1 is set to an applied voltage of 100 V in a normal temperature and humidity environment of a temperature of 23 ± 2 ° C. and a relative humidity of 55 ± 2%. It shall be expressed with the value measured by the following method under the above conditions.

That is, an aluminum drum 14 that can be rotated at a constant rotational speed is prepared, and the outer peripheral surface 4 (oxide film) of the semiconductive roller 1 that is fixed to the outer peripheral surface 15 of the aluminum drum 14 by inserting the shaft 3 from above. 5 is formed, the outer peripheral surface 4) on which the oxide film 5 is formed is brought into contact.
A DC power supply 16 and a resistor 17 are connected in series between the shaft 3 and the aluminum drum 14 to constitute a measurement circuit 18. The DC power source 16 is connected to the shaft 3 on the (−) side and to the resistor 17 on the (+) side. The resistance value r of the resistor 17 is 100Ω.

  Next, the aluminum drum 14 is rotated (rotation number: 30 rpm) in a state where the outer peripheral surface 4 of the semiconductive roller 1 is pressed against the aluminum drum 14 by applying a load F of 500 g to both ends of the shaft 3. The detection voltage V applied to the resistor 17 when the applied voltage E of 100 V DC is applied from the DC power source 16 between them is measured 100 times in 4 seconds to obtain the average value.

From the average value of the detection voltage V and the applied voltage E (= 100 V), the roller resistance value R (Ω) of the semiconductive roller 1 is basically the formula (a) ′:
R = r × E / (V−r) (a) ′
Sought by. However, since the -r term in the denominator in the formula (a) ′ can be regarded as being minute, in the present invention, the formula (a):
R = r × E / V (a)
It is assumed that the roller resistance value R (Ω) of the semiconductive roller 1 is the value obtained by the above.

Note that the configuration of the present invention is not limited to the example illustrated in the above description.
For example, the semiconductive roller 1 is not limited to a single layer, and may be formed in a laminated structure including two rubber layers, an outer layer on the outer peripheral surface 4 side and an inner layer on the shaft 3 side.
The semiconductive roller manufactured by the manufacturing method of the present invention includes a charging roller, a developing roller, a laser roller, an electrostatic copying machine, a plain paper facsimile machine, or a combination of these as a transfer roller, a cleaning roller, etc. It can be used for an image forming apparatus using electrophotography.

<Example 1>
(Preparation of rubber composition)
The following rubber components were blended.
(A) ECO [Epichromer (registered trademark) D manufactured by Daiso Corporation, ethylene oxide content: 61 mol%] 15 parts by mass
(B) GECO [Epion (registered trademark) -301L manufactured by Daiso Corporation, EO / EP / AGE = 73/23/4 (molar ratio)] 45 parts by mass
(C) CR [Showen (registered trademark) WRT manufactured by Showa Denko KK] 10 parts by mass
(D) NBR [JSR N250 SL manufactured by JSR Corporation, low nitrile NBR, acrylonitrile content: 20%] 30 parts by mass Using 100 parts by mass of the above rubber components (A) to (D) using a Banbury mixer While kneading, first of all, the components shown in Table 1 below were added and kneaded, and finally the crosslinking component was added and further kneaded to prepare a rubber composition.

Each component in Table 1 is as follows. In addition, the mass part in a table | surface is a mass part per 100 mass parts of total amounts of a rubber part.
Ion salt: Potassium bis (trifluoromethanesulfonyl) imide [EF-N112 manufactured by Mitsubishi Materials Electronics Chemical Co., Ltd.]
Acid acceptor: Hydrotalcite [DHT-4A (registered trademark) -2 manufactured by Kyowa Chemical Industry Co., Ltd.]
Acceleration aid: 2 types of zinc oxide [Mitsui Metal Mining Co., Ltd.]
Filler: Conductive carbon black [acetylene black, Denka Black (registered trademark) manufactured by Denki Kagaku Kogyo Co., Ltd., granular]
Processing aid: Zinc stearate [SZ-2000 manufactured by Sakai Chemical Industry Co., Ltd.]
Anti-aging agent: Nickel dibutyldithiocarbamate [NOCRACK (registered trademark) NBC manufactured by Ouchi Shinsei Chemical Co., Ltd.]
Thiourea-based cross-linking agent: ethylenethiourea [2-mercaptoimidazoline, Axel (registered trademark) 22-S manufactured by Kawaguchi Chemical Co., Ltd.]
Accelerator DT: 1,3-di-o-tolylguanidine [guanidine accelerator, Sunseller (registered trademark) DT manufactured by Sanshin Chemical Industry Co., Ltd.]
Dispersible sulfur: cross-linking agent [trade name Sulfax PS manufactured by Tsurumi Chemical Co., Ltd., sulfur content: 99.5%]
Accelerator DM: di-2-benzothiazolyl disulfide [thiazole accelerator, Noxeller (registered trademark) DM manufactured by Ouchi Shinsei Chemical Co., Ltd.]
Accelerator TS: Tetramethylthiuram monosulfide [Thiuram accelerator, Sunseller TS manufactured by Sanshin Chemical Industry Co., Ltd.]
(Manufacture of semi-conductive rollers)
The rubber composition was supplied to an extrusion molding machine having a diameter of 60 mm and extruded into a cylindrical shape having an outer diameter of 16.5 mm and an inner diameter of 5.5 mm to produce a cylindrical body 13.

Then the cylindrical body 13, of the tray 1 shown in FIG. 1 (a) (b), in a state where the radius R ₁ of the inner bottom surface 7 is housed in the housing groove 8 is 11.5 mm, in the vulcanizer 160 Crosslinking was carried out at 30 ° C. for 30 minutes.
The radius R ₁ of the inner bottom surface 7 of the housing groove 8 was 1.39 times the radius R ₂ (= 8.25 mm) of the cylindrical body 13.
The cross-linked cylindrical body was reattached to a metal shaft having an outer diameter of φ6 mm coated with a conductive thermosetting adhesive (polyamide type) on the outer peripheral surface, and heated in an oven at 150 ° C. for 60 minutes, After being bonded to the metal shaft and cutting both ends, the outer peripheral surface was dry-polished using a wide polishing machine until the outer diameter was 9.5 mm.

After the outer peripheral surface 4 after polishing is wiped with alcohol, the distance from the UV light source to the outer peripheral surface is set to 50 mm and set in a UV processing apparatus, and the oxide film 5 is formed by irradiating with ultraviolet rays for 15 minutes while rotating at 30 rpm. A semiconductive roller 1 was produced.
<Examples 2 to 4, Comparative Examples 1 and 2>
The inner bottom surface 7 has a receiving groove 8 having a radius R ₁ of 8 mm (Comparative Example 1), 9 mm (Example 2), 15 mm (Example 3), 21 mm (Example 4), and 22 mm (Comparative Example 5). A semiconductive roller 1 was produced in the same manner as in Example 1 except that the tray 1 was used.

The radius R ₁ of the inner bottom surface 7 of the receiving groove 8 is 0.97 times (Comparative Example 1) and 1.09 times (Example 2) of the radius R ₂ (= 8.25 mm) of the cylindrical body 13. They were 82 times (Example 3), 2.55 times (Example 4), and 2.67 times (Comparative Example 2).
<Dent evaluation>
The cylindrical body 13 immediately after cross-linking during the production in each of the above Examples and Comparative Examples was observed, and the presence or absence of a dent was evaluated according to the following criteria.

A: No dent was seen at all.
○: Although a slight dent was seen, it was a level that could be corrected by polishing after inserting the core metal.
X: The dent which cannot be corrected by grinding | polishing was seen.
<Bending evaluation>
The cylindrical body 13 was observed, and the presence or absence of bending was evaluated according to the following criteria.

(Double-circle): The curve was not seen at all.
○: Although a slight curve was seen, it was a level that could be corrected by polishing after inserting the cored bar into the through hole.
X: The curve which cannot be corrected by grinding | polishing was seen.
<Evaluation of uniformity of roller resistance>
In the above-mentioned measurement of the roller resistance value, the roller resistance value is obtained from each measured value measured 100 times in 4 seconds by the equation (a), and the maximum value and the minimum value are extracted. The ratio (maximum value) / (minimum value) was obtained, and the uniformity of the roller resistance value was evaluated according to the following criteria.

A: The above ratio was 1.2 or less.
○: The above ratio exceeded 1.2 and was 2.0 or less.
X: The above ratio exceeded 2.0.
The results are shown in Table 2.

From the results of Examples 1 to 4 and Comparative Examples 1 and 2 in Table 2, the cross-sectional shape of the inner bottom surface of the tubular body before cross-linking is 1.05 times or more the radius R ₂ of the tubular body, 2.6. By bridging in a state of being accommodated in a linear accommodation groove having an arcuate concave curved surface having a radius R ₁ less than double, the temporary core insertion process is eliminated, and the productivity is higher than the current level. It has been found that a good semiconductive roller free from dents, curvatures, unevenness in roller resistance, etc. can be produced.

DESCRIPTION OF SYMBOLS 1 Semiconductive roller 2 Through-hole 3 Shaft 4 Outer peripheral surface 5 Oxide film 6 Tray 7 Inner bottom surface 8 Accommodating groove 9 Substantially semi-cylindrical body 10 Frame body 11 Rod 12 Guide 13 Cylindrical body 14 Aluminum drum 15 Outer peripheral surface 16 DC power supply 17 Resistance 18 Measuring circuit F Load L ₁ Length L ₂ Full length R ₁ Radius R ₂ Radius V Detection voltage

Claims (2)

  A rubber composition having semiconductivity and crosslinkability is extruded through a head of an extruder into a cylinder having a predetermined radius, and then cut into a predetermined length to form a cylindrical body. The cross-sectional shape is an arc-shaped concave curved surface having a radius not less than 1.05 times and not more than 2.6 times the radius of the cylindrical body, and has a length that is not less than the total length after cutting of the cylindrical body. A method for producing a semiconductive roller, comprising a step of heating and crosslinking in a vulcanizing can in a state of being accommodated in a linear accommodation groove having the same.   The manufacturing method of the semiconductive roller of Claim 1 which bridge | crosslinks several cylindrical bodies simultaneously using the tray which arrange | positioned the said accommodating groove | channel in parallel and mutually mutually.

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