JP2007072445A - Semiconductive roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductive roll on which toner is hardly deposited, resulting in not hindering the movement of the toner due to electrostatic force. <P>SOLUTION: The semiconductive roll has a toner carrier. At least the outermost layer of the toner carrier is formed with resin or rubber, which includes the resin or rubber having at least a chlorine atom, and further which includes titanium oxide at the rate of 3-60 mass part with respect to the resin or rubber having the chlorine atom of 100 mass part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductive roll, and more particularly to a semiconductive roll having a toner conveying portion used as a developing roll, a cleaning roll, a charging roll, a transfer roll or the like mounted on an electrophotographic apparatus.

  In electrophotographic printing technology, improvements such as high speed, high image quality, colorization, and miniaturization have progressed, and have been widely spread throughout the world. The key to these improvements is toner. In order to satisfy all the above requirements, it is necessary to make the toner finer, make the toner particle size uniform, and make the toner spherical. With respect to toner miniaturization, toner particles having a particle diameter of 10 μm or less, and further 5 μm or less have come out. As for the spheroidization of the toner, the sphericity is over 99%. Furthermore, in order to improve image quality, polymerized toners are becoming the mainstream in place of conventional pulverized toners. Such polymerized toner has very good dot reproducibility when digital information is printed, and a high-quality printed material can be obtained.

  Corresponding to such miniaturization, uniformization and spheroidization of toner, and transfer to polymerized toner, in the image forming mechanism of electrophotographic devices such as laser beam printers, it imparts high chargeability to the toner and adheres the toner A semiconductive roll is particularly useful as a developing roll that can be efficiently transported to a photoconductor without causing the photoconductive member to be transported, and furthermore, the high-performance functions of this semiconductive roll are maintained until the end of the service life of the product. It is required to make it.

  On the other hand, for example, in Japanese Patent Application Laid-Open No. 2004-170845 (Patent Document 1) proposed by the present inventor, an ion conductive rubber having uniform electrical characteristics is used and a dielectric loss tangent adjusting filler is blended. A conductive rubber roll having a tangent of 0.1 to 1.5 is described. When the conductive rubber roll is used, an appropriate and high charge can be added to the toner, and as a result, a high-quality initial image can be obtained. Furthermore, the charge amount of the toner hardly decreases even after the number of printed sheets, and as a result, high image quality can be maintained.

In Patent Document 1, a rubber component containing a chlorine atom represented by epichlorohydrin rubber may be used in order to obtain ionic conductivity. In this case, the rubber component containing the chlorine atom generally has a high surface free energy and tends to adhere to the toner and the toner external additive.
In addition, when an ethylene oxide monomer exhibiting ionic conductivity is polymerized, the surface free energy is increased and wettability is facilitated, and the adhesion of the toner to the semiconductive member is increased.
Further, when an oxide film is formed by subjecting the surface to ultraviolet irradiation or ozone exposure, the oxygen concentration in that portion increases, so that the surface free energy increases and the adhesion of the toner to the semiconductive member may further increase.
In addition, when the dielectric loss tangent is 0.1 to 1.5, the chargeability of the toner can be improved and the amount of toner transport can be reduced, so that a high-quality image such as a halftone image can be realized. Since the toner lamination amount is reduced, there is a possibility that the toner adheres more to the developing roll.

The adhesion of toner to such a semiconductive member does not affect the very initial image or the continuously printed image. However, for example, when printing is performed under the following conditions, the influence is ignored. become unable. For example, normally charged toner is transported to a photosensitive member having the opposite charge by electrostatic force (Coulomb force). Since the adhesion between the toner and the developing roll is strong, the transport of toner by this electrostatic force is hindered. However, there is a problem that the printing density is lowered even though the amount of charge added to the ink does not change.
・ When printing is performed moderately and the toner is comparatively blended with the developing roll (for example, when about 2,000 1% printed images are printed)
・ When the average particle size of the toner is 8 μm or less, especially 6 μm or less ・ When continuous printing is not performed, for example, when printing is stopped for one day and then printed the next day ・ When used in a low temperature and low humidity environment where the toner charge amount is relatively high When using a printer with high toner charge for high image quality

Japanese Patent Application Laid-Open No. 2004-271757 (Patent Document 2) discloses a developing roll having a blasted surface that has been blasted and having oxide powder such as titanium oxide attached to a peak portion of the blasted surface. Are listed.
In the developing roll, the oxide powder adheres to the peak portion of the blasting surface, so that the surface roughness is alleviated and the toner is not overcharged. Even in the initial stage, there is an advantage that image defects such as black spots do not occur.

However, as described in claim 4 of Patent Document 2, the oxide powder is only applied to the blasted surface and attached to the peak portion. In Patent Document 2, page (2), right column, lines 41 to 42, it is described that “the surface of the developing sleeve is shaved to some extent, and the peak of the uneven surface is not rough”. Therefore, the oxide powder adhering to the peak portion of the blasted surface falls off after the initial stage and does not exhibit the effect over a long period of time.
Furthermore, Patent Document 2 does not describe or suggest reduction of toner adhesion to the developing roll.

JP 2004-170845 A JP 2004-271757 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductive roll that does not easily adhere toner and consequently does not hinder toner movement due to electrostatic force.

  In order to solve the above-mentioned problems, the present invention provides a semiconductive roll having a toner conveying portion, wherein the toner conveying portion is formed of at least an outermost layer of resin or rubber, and the resin or rubber is at least chlorine. A semiconductive roll comprising a resin or rubber having atoms and further containing titanium oxide at a ratio of 3 to 60 parts by mass with respect to 100 parts by mass of a resin or rubber having chlorine atoms. Yes.

In the semiconductive roll of the present invention, at least the outermost layer is formed of resin or rubber. The resin or rubber constituting the outermost layer includes at least a resin or rubber having a chlorine atom.
The resin or rubber having a chlorine atom may be a known resin or rubber as long as it has a chlorine atom. For example, chloroprene rubber, chlorinated butyl, chlorosulfonated polyethylene, chlorinated polyethylene, vinyl chloride, etc. Examples thereof include a conductive resin or rubber, such as a conductive resin or rubber, or an epichlorohydrin copolymer.

When a non-conductive resin or rubber is used as the resin or rubber having a chlorine atom, it is preferably combined with the ion conductive resin or rubber in order to make the outermost layer ion conductive. Examples of the ion conductive resin or rubber include a copolymer containing ethylene oxide. Examples of the copolymer containing ethylene oxide include a polyether copolymer and an epichlorohydrin copolymer.
Of course, even when a conductive resin or rubber is used as the resin or rubber having a chlorine atom, an ion conductive resin or rubber having no chlorine atom may be combined.

  The resin or rubber constituting the outermost layer may include a resin or rubber other than those described above. Examples thereof include acrylonitrile butadiene rubber (NBR), acrylonitrile rubber, butadiene rubber, styrene butadiene rubber, urethane rubber, butyl rubber, fluorine rubber, isoprene rubber, and silicone rubber. Also, low resistance polymers such as binary copolymers of unsaturated epoxides such as allyl glycidyl ether, glycidyl methacrylate, glycidyl acrylate or butadiene monoxide and propylene oxide can be exemplified. These can be used alone or in combination of two or more.

  Examples of the resin or rubber constituting the outermost layer include (1) epichlorohydrin copolymer alone, (2) a combination of chloroprene rubber and epichlorohydrin copolymer and / or polyether copolymer, (3) A combination of chloroprene rubber, NBR, and epichlorohydrin copolymer or / and polyether copolymer, and (4) a combination of chloroprene rubber and NBR is preferable. Of these, a combination of chloroprene rubber and epichlorohydrin copolymer, or a combination of chloroprene rubber, epichlorohydrin copolymer and polyether copolymer is particularly preferable.

When two or more kinds of resins or rubbers are combined as the resin or rubber constituting the outermost layer, the blending ratio may be appropriately selected.
For example, when combining a chloroprene rubber and an epichlorohydrin copolymer, if the total mass of the rubber component is 100 parts by mass, the content of the epichlorohydrin copolymer is 5 to 95 parts by mass, preferably 20 to 80 parts by mass, The content of the chloroprene rubber (C) is 5 to 95 parts by mass, preferably 20 to 80 parts by mass.
When combining chloroprene rubber, epichlorohydrin copolymer and polyether copolymer, if the total mass of the rubber component is 100 parts by mass, the content of epichlorohydrin copolymer is 5 to 90 parts by mass, preferably 10 parts. ˜70 parts by mass, polyether copolymer content is 5 to 40 parts by mass, preferably 5 to 20 parts by mass, and chloroprene rubber content is 5 to 90 parts by mass, preferably 10 to 80 parts by mass. Is preferred. By setting it as such a mixture ratio, three components can be disperse | distributed well and the physical properties including intensity | strength can be improved. More preferably, it is epichlorohydrin copolymer: chloroprene rubber: polyether copolymer = 2 to 5: 4 to 7: 1 by mass ratio.

  Examples of the epichlorohydrin-based copolymer include epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide copolymer, epichlorohydrin-propylene oxide copolymer, epichlorohydrin-allyl glycidyl ether copolymer, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer. Examples thereof include an epichlorohydrin-propylene oxide-allyl glycidyl ether copolymer and an epichlorohydrin-ethylene oxide-propylene oxide-allyl glycidyl ether copolymer.

  As the epichlorohydrin copolymer, a copolymer containing ethylene oxide is preferable, and the ethylene oxide content is 30 mol% to 95 mol%, preferably 55 mol% to 95 mol%, more preferably 60 mol% to 80 mol. % Or less is particularly preferred. Ethylene oxide has a function of lowering the volume resistivity, but if the ethylene oxide content is less than 30 mol%, the effect of reducing the volume resistivity is small. On the other hand, if the ethylene oxide content exceeds 95 mol%, crystallization of ethylene oxide occurs and the segmental movement of the molecular chain is hindered, and conversely, the volume resistivity tends to increase and the hardness of the vulcanized rubber increases. And the problem of increased viscosity of rubber before vulcanization is likely to occur.

Especially, it is especially preferable to use an epichlorohydrin (EP) -ethylene oxide (EO) -allyl glycidyl ether (AGE) copolymer as an epichlorohydrin type copolymer. A preferable content ratio of EO: EP: AGE in the copolymer is EO: EP: AGE = 30 to 95 mol%: 4.5 to 65 mol%: 0.5 to 10 mol%, and a more preferable ratio is EO: EP: AGE = 60-80 mol%: 15-40 mol%: 2-6 mol%.
Moreover, as an epichlorohydrin-type copolymer, an epichlorohydrin (EP) -ethylene oxide (EO) copolymer can also be used. A preferable content ratio of EO: EP in the copolymer is EO: EP = 30 to 80 mol%: 20 to 70 mol%, and a more preferable ratio is EO: EP = 50 to 80 mol%: 20 to 50 mol. %.

  When the epichlorohydrin copolymer is blended, the blending amount is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. Further preferred.

  Examples of the polyether copolymer include ethylene oxide-propylene oxide-allyl glycidyl ether copolymer, ethylene oxide-allyl glycidyl ether copolymer, propylene oxide-allyl glycidyl ether copolymer, ethylene oxide-propylene oxide. Examples thereof include a copolymer or urethane rubber.

  As the polyether copolymer, a copolymer containing ethylene oxide is preferable, and a copolymer having an ethylene oxide content of 50 to 95 mol% is more preferable. Higher ethylene oxide ratios can stabilize more ions and lower resistance, but if the ethylene oxide ratio is increased too much, crystallization of ethylene oxide occurs and hinders the molecular chain segment movement. This is because the volume resistivity may increase.

The polyether copolymer preferably contains allyl glycidyl ether in addition to ethylene oxide. By copolymerizing allyl glycidyl ether, this allyl glycidyl ether unit itself obtains free volume as a side chain, so that crystallization of the ethylene oxide can be suppressed, and as a result, unprecedented low resistance can be achieved. realizable. Furthermore, it is possible to crosslink with other rubber by introducing a carbon-carbon double bond by copolymerization of allyl glycidyl ether, and co-crosslinking with other rubber can prevent bleeding and photoreceptor contamination. it can.
The allyl glycidyl ether content in the polyether copolymer is preferably 1 to 10 mol%. If it is less than 1 mol%, bleed or photoconductor contamination is likely to occur. If it exceeds 10 mol%, no further effect of suppressing crystallization is obtained, and the number of crosslinking points after vulcanization increases. On the other hand, low resistance cannot be realized, and tensile strength, fatigue characteristics, flex resistance, and the like are deteriorated.

  As the polyether-based copolymer used in the present invention, it is particularly preferable to use an ethylene oxide (EO) -propylene oxide (PO) -allyl glycidyl ether (AGE) terpolymer. By copolymerizing propylene oxide, crystallization by ethylene oxide can be further suppressed. A preferable content ratio of EO: PO: AGE in the polyether-based copolymer is EO: PO: AGE = 50 to 95 mol%: 1 to 49 mol%: 1 to 10 mol%. Further, in order to more effectively prevent bleeding and photoreceptor contamination, the EO-PO-AGE terpolymer preferably has a number average molecular weight Mn of 10,000 or more.

  When the polyether copolymer is blended, the blending amount is preferably 5 parts by mass or more and more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component.

Chloroprene rubber is a chloroprene polymer produced by emulsion polymerization, and is classified into a sulfur-modified type and a non-sulfur-modified type depending on the type of molecular weight regulator.
In the sulfur-modified type, a polymer obtained by copolymerizing sulfur and chloroprene is plasticized with thiuram disulfide or the like and adjusted to a predetermined Mooney viscosity. Examples of non-sulfur-modified types include mercaptan-modified types and xanthogen-modified types. The mercaptan-modified type uses an alkyl mercaptan such as n-dodecyl mercaptan, tert-dodecyl mercaptan or octyl mercaptan as a molecular weight regulator. The xanthogen-modified type uses an alkyl xanthogen compound as a molecular weight regulator.
The chloroprene rubber is classified into a medium crystallization speed type, a low crystallization speed type, and a high crystallization speed type depending on the crystal acceleration of the produced chloroprene rubber.
In the present invention, any type may be used, but a type that is non-sulfur modified and has a low crystallization rate is preferred.
In the present invention, a rubber or elastomer having a structure similar to that of chloroprene rubber can be used as the chloroprene rubber. For example, a copolymer obtained by polymerizing a mixture of chloroprene and one or more other copolymerizable monomers may be used. Examples of monomers copolymerizable with chloroprene include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, sulfur, styrene, acrylonitrile, methacrylonitrile, isoprene, butadiene and acrylic. Examples include acids, methacrylic acid, and esters thereof.

  When blending chloroprene rubber, the blending amount can be appropriately selected within the range of 1 to 100 parts by mass with respect to 100 parts by mass of the rubber component. However, in view of the effect of imparting charging property, it is preferable that the chloroprene rubber is contained in an amount of about 5 parts by mass or more with respect to 100 parts by mass of the rubber component. Furthermore, it is more preferable that it is contained about 10 parts by mass or more from the viewpoint of rubber uniformity. The upper limit of the amount is preferably 80 parts by mass or less, and more preferably 60 parts by mass or less.

NBR is a low nitrile NBR with an acrylonitrile content of 25% or less, a medium nitrile NBR with an acrylonitrile content of 25-31%, a medium-high nitrile NBR with an acrylonitrile content of 31-36%, and an acrylonitrile content of 36% or more. Any of high nitrile NBR may be used.
In the present invention, it is preferable to use a low nitrile NBR having a small specific gravity in order to reduce the specific gravity of the rubber. In view of miscibility with chloroprene rubber, it is preferable to use medium nitrile NBR or low nitrile NBR. More specifically, from the viewpoint of solubility parameters, the acrylonitrile content is 15 to 39%, preferably 17 to 35%, more preferably. It is preferred to use 20-30% NBR.

  When mix | blending NBR, it is preferable that the content is 5-65 mass parts with respect to 100 mass parts of all the rubber components, It is more preferable that it is 10-65 mass parts, It is 20-50 mass parts. More preferred. Since the charge amount of the toner is reduced, the NBR content is preferably 65 parts by mass or less. In order to substantially suppress the increase in hardness and reduce the temperature dependence, the NBR content is 5 parts by mass. The above is preferable.

The semiconductive roll of the present invention is characterized by containing titanium oxide at a ratio of 3 to 60 parts by mass with respect to 100 parts by mass of the above-described resin or rubber having a chlorine atom.
It does not specifically limit as a titanium oxide used by this invention, What is necessary is just to use a well-known thing. As the crystal system, any one of anatase type, rutile type, mixed crystal type thereof, and amorphous type can be used. Among them, rutile type titanium oxide is preferably used. Titanium oxide is obtained, for example, by the sulfuric acid method or the chlorine method, or by low-temperature oxidation (thermal decomposition or hydrolysis) of a volatile titanium compound such as titanium alkoxide, titanium halide or titanium acetylacetonate.
The titanium oxide used in the present invention preferably contains 50% or more of particles having a particle size of 0.5 μm or less. This is because the dispersibility of titanium oxide is improved in this case. Especially, it is preferable to use the titanium oxide whose average particle diameter is 0.1-0.5 micrometer.

  The reason why the amount of titanium oxide is 3 to 60 parts by mass with respect to 100 parts by mass of the resin or rubber having chlorine atoms is that when the amount of titanium oxide is less than 3 parts by mass, the toner adhesion due to titanium oxide is reduced. If the blending amount of titanium oxide exceeds 60 parts by mass, the hardness of the outermost layer becomes too high, or proper charge cannot be applied to the toner. As for the compounding quantity of a titanium oxide, it is more preferable that it is 5-60 mass parts.

The roll of the present invention has semiconductivity. Specifically, it is preferable that the roll resistance is ¹⁰ 5 to 10 ⁸ Omega at an applied voltage of 100 ^V, and more preferably 10 5 ~10 ⁷ Ω.
The roll electric resistance is preferably 10 ⁵ Ω or more in order to control the flowing current to suppress the occurrence of image defects and prevent discharge to the photoreceptor. In addition, for example, the efficiency of toner supply and the like is maintained, and when the toner moves to the photosensitive member, a voltage drop of the developing roller occurs, and after that, the toner cannot be reliably conveyed from the developing roller to the photosensitive member, thereby preventing image defects. In order to prevent this, the roll electrical resistance is preferably 10 ⁸ Ω or less. Further, if it is 10 ⁷ Ω or less, it can be used in a wider range of environments and is extremely useful. The roll electrical resistance is measured by the method described in the examples.

Although there exist electronic conductivity and ionic conductivity in electroconductivity, since it can acquire more uniform electrical property, it is preferable to have ionic conductivity.
When the resin or rubber constituting the outermost layer contains a resin or rubber exhibiting ionic conductivity, it can be made ionic conductive by adjusting the blending amount thereof. Of course, the following ion conductive agent may be used in combination.
When the resin or rubber constituting the outermost layer does not contain a resin or rubber exhibiting ionic conductivity, an ionic conductive agent is added.

Various ion conductive agents can be selected, and examples thereof include a salt having an anion having a fluoro group (F—) and a sulfonyl group (—SO ₂ —). More specifically, a salt of bisfluoroalkylsulfonylimide, a salt of tris (fluoroalkylsulfonyl) methane, a salt of fluoroalkylsulfonic acid, or the like can be given. The cation paired with the anion in the salt is preferably an alkali metal, group 2A or other metal ion, more preferably a lithium ion. Specific examples of the ion conductive agent include LiCF ₉ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiC (SO ₂ CF ₃ ), LiCH (SO ₂ CF ₃ ) ₂ , LiSF ₆ CF ₂ SO _{3, and the} like. Can be mentioned.
Although the compounding quantity of an ionic conductive agent can be suitably selected according to the kind, it is preferable that it is 0.1-5 mass parts with respect to 100 mass parts of rubber components, for example.

  If desired, an electronic conductivity may be added to add electronic conductivity. Examples of electronic conductive agents include conductive carbon blacks such as ketjen black, furnace black or acetylene black; conductive metal oxides such as zinc oxide, potassium titanate, antimony-doped titanium oxide, tin oxide or graphite; carbon fibers, etc. Can be mentioned. The blending amount of the electronic conductive agent may be appropriately selected while observing physical properties such as an electric resistance value, and is, for example, about 5 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

In the semiconductive roll of the present invention, in order to impart high chargeability to the toner and to improve the sustainability of the chargeability, the dielectric loss tangent when an AC voltage is applied at a voltage of 5 V and a frequency of 100 Hz is set to 0. 1 to 1.8.
In the electrical characteristics of the semiconductive roll, the dielectric loss tangent is an index indicating the degree of influence of the electric flow (conductivity) and the capacitor component (capacitance), and indicates the phase delay when an alternating current is applied. It is also a parameter and indicates the size of the capacitor component ratio when voltage is applied. That is, the dielectric loss tangent is expressed by the amount of charge generated when the toner comes into contact with the developing roll at a high pressure by the amount regulating blade and the amount of charge that escapes onto the roll before being conveyed to the photoreceptor. It becomes an index indicating the charge amount.
When the dielectric loss tangent is large, it is easy to pass electricity (electric charge) and the polarization does not proceed easily. Conversely, when the dielectric loss tangent is small, it is difficult for electricity (electric charge) to pass therethrough and the polarization proceeds. Therefore, the smaller the dielectric loss tangent, the higher the capacitor-like characteristics of the roll, and the charge on the toner generated by frictional charging can be maintained without escaping from the roll. That is, chargeability can be added to the toner, and the added chargeability can be maintained. In order to obtain such an effect, the dielectric loss tangent is set to about 1.8 or less. In addition, in order to prevent the charge amount from being excessively increased and the printing density from being excessively decreased, and further to prevent the amount of the additive for adjusting the dielectric loss tangent from increasing and becoming hard, the dielectric loss tangent is set to about 0.1 or more. Yes.
The lower limit of the dielectric loss tangent is more preferably 0.3 or more, most preferably 0.5 or more, and the upper limit is more preferably 1.5 or less, still more preferably 1.0 or less, and most preferably 0.8 or less.

The dielectric loss tangent is measured by the method described in Examples described later.
A minute voltage of 5 V is applied as a dielectric tangent measurement condition when the semiconductive roll is a developing roll, when the developing roll holds toner, or when the toner is conveyed to a photoreceptor. This is because extremely small voltage fluctuations occur.
The reason why the frequency is set to 100 Hz is that a low frequency of about 100 Hz is extremely suitable for the event considering the rotation speed of the developing roll, the nip with the photosensitive member, blade, and toner supply roll that are in contact with or close to the developing roll. is there.

  In order to control the dielectric loss tangent of the semiconductive roll within the predetermined range, a dielectric loss tangent adjusting agent is blended with the resin or rubber constituting the outermost layer. Examples of the dielectric loss tangent adjusting agent include weakly conductive carbon black or calcium carbonate treated with a fatty acid. Among these, it is preferable to use weakly conductive carbon black. If calcium carbonate treated with fatty acid is used, it may become familiar with titanium oxide and partly agglomerate to grow into large particles, which may impair dispersibility. This is because carbon black has extremely good dispersibility with titanium oxide.

Weakly conductive carbon black is a carbon black with a large particle size, small structure development, and small contribution to conductivity. By blending this, it is possible to obtain a capacitor-like function by polarization without increasing conductivity. Therefore, it is possible to control the chargeability without impairing the uniformity of electric resistance.
If the weak conductive carbon black has a primary particle size of 80 nm or more, preferably 100 nm or more, the above effect can be obtained more effectively. Further, when the primary particle size is 500 nm or less, preferably 250 nm or less, the surface roughness can be extremely reduced. The weakly conductive carbon black is preferably spherical or nearly spherical because of its small surface area.
Various types of weakly conductive carbon black can be selected. Among them, carbon black produced by a furnace method or a thermal method that easily obtains a large particle size is preferable, and furnace carbon black is more preferable. In terms of carbon classification, SRF, FT, and MT are preferable. Carbon black used as a pigment may also be used.

The blending amount of the weakly conductive carbon black is preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component in order to substantially exhibit the effect of reducing the dielectric loss tangent, and the other members that are brought into contact with increasing hardness. Is preferably 70 parts by mass or less in order to avoid the risk of damaging the film and to avoid a decrease in wear resistance. Further, in order to obtain a so-called ionic conductivity characteristic in which the voltage fluctuation of the roll resistance is small with respect to the applied voltage, the blending of 70 parts by mass or less is preferable.
The blending amount of the weakly conductive carbon black is more preferably 10 to 60 parts by mass, and particularly preferably 25 to 55 parts by mass from the viewpoint of miscibility with other components.

The fatty acid-treated calcium carbonate has a higher activity than ordinary calcium carbonate due to the presence of the fatty acid at the interface of calcium carbonate, and is easily slippery, so that high dispersion can be realized easily and stably. When the polarization action is promoted by the fatty acid treatment, the function of the capacitor in the rubber is strengthened by the action of the two actions, so that the dielectric loss tangent can be efficiently reduced. As the calcium carbonate subjected to the fatty acid treatment, those in which a fatty acid such as stearic acid is coated on the entire surface of the calcium carbonate particles are preferable.
The compounding amount of the fatty acid-treated calcium carbonate is 30 to 80 parts by mass, preferably 40 to 70 parts by mass with respect to 100 parts by mass of the rubber component. In order to substantially exhibit the effect of reducing the dielectric loss tangent, it is preferably 30 parts by mass or more, and in order to avoid an increase in hardness and fluctuation in resistance, it is preferably 80 parts by mass or less.

In the semiconductive roll of the present invention, an oxide film is preferably formed on the surface of the outermost layer. Since the oxide film becomes a dielectric layer and the dielectric loss tangent of the semiconductive roll can be reduced, the dielectric loss tangent can be easily controlled within a predetermined range. Further, since the oxide film becomes a low friction layer, toner separation is improved and image formation is easily performed, and as a result, a better image can be obtained.
As the oxide film, an oxide film having many C═O groups or C—O groups is preferable. The oxide film is formed by subjecting the surface of the outermost layer to a treatment such as ultraviolet irradiation and / or ozone irradiation, and oxidizing the surface portion of the outermost layer. In particular, it is preferable to form an oxide film by ultraviolet irradiation because the processing time is fast and the cost is low.

The treatment for forming the oxide film can be performed according to a known method. For example, in the case of performing ultraviolet irradiation, although depending on the distance between the surface of the outermost layer and the ultraviolet lamp, the type of rubber, and the like, the wavelength of 100 to 400 nm, more preferably 100 to 300 nm, for 30 seconds to 30 minutes, preferably The irradiation is preferably performed while rotating the semiconductive roll for about 1 minute to 10 minutes. However, the intensity of ultraviolet rays and the irradiation conditions (time, bath temperature, distance) must be selected so that the dielectric loss tangent can be controlled within the range defined by the present invention.
Moreover, when performing ultraviolet irradiation, the rubber | gum which is easy to deteriorate with ultraviolet rays, such as NBR, has a preferable compounding of 50 mass parts or less. Addition of chloroprene and chloroprene rubber is particularly effective when irradiated with ultraviolet rays.

  When the roll electrical resistance when the voltage 50V is applied to the semiconductive roll before the oxide film formation is R50 and the roll electrical resistance at the applied voltage 50V after the oxide film formation is R50a, log (R50a) -log (R50 ) = Preferably about 0.2 to 1.5. This range is preferable from the viewpoints of improving durability, reducing resistance change when using a semiconductive roll, reducing stress on the toner, and measures against collapse of the photoreceptor. Since the roll electric resistance at a low voltage of 50 V at which a voltage can be stably loaded as described above is used as an index value, a minute increase in resistance due to oxide film formation can be accurately captured. In addition, as for a more preferable range, a minimum is 0.3, especially 0.5 is preferable, and an upper limit is 1.2, especially 1.0 is preferable.

The semiconductive roll of the present invention preferably has a surface friction coefficient of 0.1 to 1.0, more preferably 0.1 to 0.8, and 0.1 to 0.6. It is more preferable. This is because, within such a range, toner chargeability can be improved and toner adhesion can be prevented. Further, when the friction coefficient of the semiconductive roll is 1.0 or more, stress such as shearing force applied to the toner becomes large. In addition, in a member that is in sliding contact with other members, heat generation and wear due to friction increase. On the other hand, when the friction coefficient of the semiconductive roll is 0.1 or less, there are inconveniences such as the toner slipping and transporting a sufficient amount of toner and it becomes difficult to sufficiently charge the toner.
As shown in FIG. 4, the friction coefficient is measured by contacting a digital force gauge ("Model PPX-2T" manufactured by Imada Co., Ltd.) 41 with a friction piece (commercial polyester OHP film, roll longitudinal direction). (The width: 50 mm) 42, a 20 g weight 44, and the conductive rubber roller 43, the numerical value measured by the digital force gauge 41 in the apparatus shown in FIG.

The semiconductive roll of the present invention preferably has a surface roughness Rz of 10 μm or less, and more preferably 8 μm or less. By reducing the surface roughness Rz, the surface of the semiconductive roll only has irregularities smaller than the particle size of the toner, so that the toner can be transported uniformly and the toner fluidity is improved. The efficiency of providing charging properties is extremely high. The surface roughness Rz is preferably as small as possible, but is usually 1 μm or more. When the surface roughness Rz is less than 1 μm, it becomes difficult to convey the toner.
The surface roughness Rz is measured according to JIS B 0601 (1994).

The semiconductive roll of the present invention has a toner transport unit having a function of transporting toner while holding the toner on the surface. The amount of toner transport in the semiconductive roll of the present invention is not particularly limited, but it is preferable that a toner amount of about 0.01 to 1.0 mg / cm ² can be transported.
The structure of the toner transport unit is not particularly limited as long as it is provided in the outermost layer that satisfies the above-described conditions, and may be a multi-layer structure such as two layers depending on the required performance. This is preferable because it can be manufactured at low cost with little variation in physical properties.

The semiconductive roll of the present invention preferably has a seal member for preventing toner leakage. Here, the “seal member” is not limited to those provided for preventing toner leakage, but includes all members that are in sliding contact with the outer peripheral surface of the semiconductive roll.
The toner tangent is preferably blended with the dielectric loss tangent adjusting agent so that the dielectric loss tangent is 0.1 to 1.8.

The semiconductive roll of the present invention is preferably used in an image forming mechanism of an electrophotographic apparatus in OA equipment such as a laser beam printer, an ink jet printer, a copying machine, a facsimile machine or an ATM.
Among these, it is suitably used as a developing roll for transporting non-magnetic one-component toner to a photoreceptor. The developing method in the image forming mechanism of the electrophotographic apparatus is roughly classified into a contact type or a non-contact type when classified according to the relationship between the photosensitive member and the developing roll, but the semiconductive roll of the present invention can be used in any method. . In particular, when the semiconductive roll of the present invention is used as a developing roll, it is preferable that it is almost in contact with the photoreceptor.
The semiconductive roll of the present invention includes a developing roll, a charging roll for uniformly charging a photosensitive drum, a transfer roll for transferring a toner image from a photosensitive member to a transfer belt or paper, and for transporting toner. It can also be used as a toner supply roll, a cleaning roll for removing residual toner, and the like.

In the present invention, even when a rubber component containing a chlorine atom having a high surface free energy is used to obtain ionic conductivity, the toner adheres to the semiconductive roll of the present invention by blending a predetermined amount of titanium oxide. Can be reduced.
The toner adhesion reduction effect by this titanium oxide blending is not affected by the type and composition of the rubber component, the presence or absence of the surface oxide film, the physical properties (particularly dielectric loss tangent) of the semiconductive roll, and the like. In addition, the effect is maintained regardless of the environment and printing conditions, and at least at the time when the toner becomes relatively familiar to the semiconductive roll over a long period of time.
As a result, when the semiconductive roll of the present invention is used as a developing roll in an image forming mechanism of an electrophotographic apparatus, a printed matter having a stable density can be obtained without lowering the printing density.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a semiconductive roll 10 used as a developing roll includes a cylindrical toner conveying unit 1 having a thickness of 0.5 to 15 mm, preferably 0.5 to 15 mm, and more preferably 3 to 8 mm. A cylindrical cored bar (shaft) 2 press-fitted into the hollow part and a seal part 3 for preventing the toner 4 from leaking are provided. The toner conveying portion 1 and the cored bar 2 are joined with a conductive adhesive. The thickness of the toner conveying portion 1 is set to 0.5 to 15 mm because if it is smaller than the above range, it is difficult to obtain an appropriate nip, and if it is larger than the above range, the member is too large to reduce the size and weight. An oxide film is formed on the outermost surface of the toner transport unit 1.
The cored bar 2 can be made of metal such as aluminum, aluminum alloy, SUS or iron, or made of ceramic.
The seal portion 3 is made of a non-woven fabric such as Teflon (registered trademark) or a sheet.

The semiconductive roll of the present invention can be prepared by a conventional method.
A method for manufacturing the semiconductive roll 10 shown in FIG. 1 will be described below.
After the components constituting the toner conveying section 1 are kneaded with a Banbury mixer, they are preformed into a tube shape with a rubber extruder, and this preformed product is vulcanized at 160 ° C. for 15 to 70 minutes. After bonding and polishing the surface, it is cut to the required dimensions and polished appropriately to form a roll. The vulcanization time may be determined by determining the optimum vulcanization time using a vulcanization test rheometer (eg, curast meter). Further, the vulcanization temperature may be determined by raising or lowering the temperature as necessary. In addition, in order to reduce contamination to other members and compression set, it is preferable to set conditions so as to obtain as much vulcanization as possible. Moreover, you may mix | blend a foaming agent etc. and may form a foam roll.

  After washing the roll with water, an oxide film is formed on the surface of the outermost layer. Specifically, using a UV irradiator, the distance between the roll and the UV lamp is 10 cm, UV light (wavelengths 184.9 nm and 253.7 nm) is irradiated for 5 minutes every 90 degrees in the circumferential direction, and the roll is rotated four times. Thus, an oxide film can be formed on the entire circumference of the roll (360 degrees).

Examples of components constituting the toner conveying unit 1 include a resin or rubber having chlorine atoms, titanium oxide, a dielectric loss tangent adjusting agent, a vulcanizing agent, and an acid accepting agent. If desired, a resin or rubber having no chlorine atom may be added.
As the resin or rubber having a chlorine atom, an epichlorohydrin copolymer and chloroprene rubber are used in combination. The compounding ratio of each rubber component is such that the content of the epichlorohydrin copolymer is 25 to 50 parts by mass and the content of the chloroprene rubber is 50 to 75 parts by mass when the total mass of the rubber component is 100 parts by mass.
As the epichlorohydrin-based copolymer, an ethylene oxide-epichlorohydrin-allyl glycidyl ether ternary copolymer having a content ratio of ethylene oxide: epichlorohydrin: allyl glycidyl ether of 60 to 80 mol%: 15 to 40 mol%: 2 to 6 mol% is used. A polymer is used.
As the chloroprene rubber, non-sulfur chloroprene rubber is used.

A polyether-based copolymer is used as the resin or rubber having no chlorine atom to be added if desired.
As the polyether copolymer, ethylene oxide-propylene oxide-allyl glycidyl ether in which the content ratio of ethylene oxide: propylene oxide: allyl glycidyl ether is 80 to 95 mol%: 1 to 10 mol%: 1 to 10 mol% A terpolymer is used. The number average molecular weight Mn of the copolymer is preferably 10,000 or more, more preferably 30,000 or more, and further preferably 50,000 or more.

  When a polyether copolymer is blended, the blending ratio of the epichlorohydrin copolymer, the polyether copolymer and the chloroprene rubber is such that the total mass of the rubber component is 100 parts by mass, and the epichlorohydrin copolymer The content is 15 to 40 parts by mass, the polyether copolymer content is 5 to 20 parts by mass, and the chloroprene rubber content is 40 to 80 parts by mass.

Rutin type titanium oxide is used as the titanium oxide. In particular, it is preferable to use titanium oxide having a particle size of 0.3 to 0.5 μm as a main component and an average particle size of 0.3 to 0.5 μm.
The compounding amount of titanium oxide is 5 to 60 parts by mass with respect to 100 parts by mass of the resin or rubber having chlorine atoms.

  As the dielectric loss tangent adjusting agent, weakly conductive carbon black is used. The weakly conductive carbon black preferably has a primary particle size of 100 to 250 nm and a spherical shape or a shape close to a spherical shape. Furthermore, it is preferable to use weakly conductive carbon black having an iodine adsorption amount of 10 to 40 mg / g, preferably 10 to 30 mg / g and a DBP oil absorption of 25 to 90 ml / 100 g, preferably 25 to 55 ml / 100 g. . The blending amount of the weakly conductive carbon black is 20 to 70 parts by mass with respect to 100 parts by mass of the rubber component.

As the vulcanizing agent, sulfur, thiourea, triazine derivative, peroxide, various monomers and the like can be used. These may be used alone or in combination of two or more. Examples of the sulfur-based vulcanizing agent include powdered sulfur, organic sulfur-containing compounds such as tetramethylthiuram disulfide or N, N-dithiobismorpholine. Examples of the thiourea vulcanizing agent include tetramethylthiourea, trimethylthiourea, ethylenethiourea, and thiourea represented by (C _n H _{2n + 1} NH) ₂ C═S (wherein _n represents an integer of 1 to 10). It is done. Examples of the peroxide include benzoyl peroxide.
The compounding amount of the vulcanizing agent is preferably 0.2 parts by mass or more and 5 parts by mass or less, and more preferably 1 part by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the rubber component.

In the present invention, it is preferable to use sulfur and thioureas in combination as the vulcanizing agent.
Sulfur is preferably contained in a proportion of 0.1 to 5.0 parts by mass, preferably 0.2 to 2 parts by mass with respect to 100 parts by mass of the rubber component. The reason for the above range is that when the amount is less than 0.1 parts by mass, the vulcanization rate of the whole composition is slowed down and the productivity tends to deteriorate. On the other hand, if the amount is larger than 5.0 parts by mass, the compression set may increase, or sulfur and the accelerator may bloom.
Moreover, it is good to mix | blend thiourea in the ratio of 0.0009 mol or more and 0.0800 mol or less in total with respect to 100 g of rubber components, Preferably it is 0.0015 mol or more and 0.0400 mol or less. By blending the thiourea within the above range, bloom and photoconductor contamination can be made difficult to occur, and lower electrical resistance can be realized because the molecular motion of the rubber is not disturbed so much. Also, the electrical resistance can be lowered as the amount of thiourea added is increased and the crosslinking density is increased. That is, if the blending amount of thiourea is less than 0.0009 mol, it is difficult to improve compression set or lower the electric resistance value. On the other hand, if it exceeds 0.0800 mol, thiourea blooms from the surface of the rubber composition and the photosensitive member is removed. This is because it is easily contaminated and mechanical properties such as elongation at break are extremely deteriorated.

Depending on the type of vulcanizing agent, a vulcanization accelerator or a vulcanization acceleration aid may be further blended.
As the vulcanization accelerator, inorganic accelerators such as slaked lime, magnesia (MgO) or risurge (PbO) and organic accelerators described below can be used. Organic promoters include guanidines such as di-ortho-tolylguanidine, 1,3-diphenylguanidine, 1-ortho-tolylbiguanide, di-ortho-tolylguanidine salt of dicatechol borate; 2-mercapto-benzothiazole or Thiazoles such as dibenzothiazyl disulfide; sulfenamides such as N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide or dipentamethylenethiuram tetrasulfide These can be used alone or in appropriate combination.
The blending amount of the vulcanization accelerator is preferably 0.5 parts by mass or more and 5 parts by mass or less, and more preferably 0.5 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the rubber component.

Examples of the vulcanization acceleration aid include metal oxides such as zinc white; fatty acids such as stearic acid, oleic acid or cottonseed fatty acid; and other conventionally known vulcanization acceleration aids.
The addition amount of the vulcanization accelerator is preferably 0.5 parts by mass or more and 10 parts by mass or less, and more preferably 2 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the rubber component.

Since the semiconductive roll of the present invention contains a resin or rubber having a chlorine atom, an acid acceptor is blended. By blending the acid acceptor, it is possible to prevent chlorine gas residue and photoconductor contamination generated during rubber vulcanization.
As the acid acceptor, various substances acting as an acid acceptor can be used. However, hydrotalcite or magnesium oxide is preferably used because of its excellent dispersibility, and in particular, hydrotalcite is used. More preferred. Furthermore, when these are used in combination with magnesium oxide or potassium oxide, a high acid-receiving effect can be obtained and contamination of the photoreceptor can be more reliably prevented.
The compounding amount of the acid acceptor is 1 part by mass or more and 10 parts by mass or less, preferably 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the rubber component. In order to effectively exhibit the effect of preventing vulcanization inhibition and photoconductor contamination, the amount of the acid acceptor is preferably 1 part by mass or more, and in order to prevent an increase in hardness, the amount of the acid acceptor is 10 parts by mass. The following is preferable.

  The toner conveying portion 1 preferably further contains alumina. By blending the toner conveying portion 1 with alumina having excellent thermal conductivity, heat generated by friction between the seal portion 3 and the outer peripheral surface of the toner conveying portion 1 can be quickly dispersed throughout the toner conveying portion. The heat transmitted to the inside of the unit can be released to the outside through the metal core 2 and is also radiated from the surface of the toner conveying unit 1 containing alumina. Therefore, wear of the seal portion 3 accelerated by heat generated by sliding friction between the seal portion 3 and the toner conveying portion 1 can be suppressed, and toner leakage can be effectively prevented for a longer period. Furthermore, since the toner conveying portion 1 does not become high temperature due to the heat generated in the sliding portion, the thermoplastic resin constituting the polymerized toner melts, and the toner becomes larger and edged and welded to become larger and angular. Can be prevented. Therefore, the durability of the seal unit 3 and the toner transport unit 1 can be significantly improved. Further, mixing alumina increases the mixing efficiency of titanium oxide, and for example, it is less likely to be detected as a foreign substance on the rubber surface.

Alumina is an oxide of aluminum (Al ₂ O ₃ ). The alumina is preferably contained in an amount of 3 to 50 parts by mass, more preferably 5 to 30 parts by mass, and more preferably 8 to 25 parts by mass with respect to 100 parts by mass of the rubber component. It is particularly preferred. When the content of alumina is 3 to 50 parts by mass, if it is 3 parts by mass or less, it is difficult to obtain an effect of releasing heat generated by sliding friction between the seal unit 3 and the toner conveying unit 1. On the other hand, when the content of alumina is 50 parts by mass or more, the hardness of the toner transport unit 1 is increased and becomes too hard, the deterioration of the toner is promoted, and the durability of the abrasive that polishes the surface of the toner transport unit 1 is increased. Will worsen and will require redress. In particular, when the alumina content is 30 parts by mass or less, there is an advantage that the miscibility with the dielectric loss tangent adjusting filler is improved.

  The alumina used in the present invention preferably has a particle size of 1 μm or less occupies 80% or more, and more preferably has a particle size of 0.5 μm or less occupies 50% or more. By using alumina having such a small particle size, there is an advantage that it can be uniformly dispersed and the heat dissipation effect is improved, and the uniformity of the surface of the toner transport portion 1 is easily secured.

  In addition to the above components, plasticizers, processing aids, deterioration inhibitors, fillers, scorch inhibitors, ultraviolet absorbers, lubricants, pigments, antistatic agents, flame retardants, neutralization, unless they are contrary to the object of the present invention You may mix | blend additives, such as an agent, a nucleating agent, an anti-bubble agent, or a crosslinking agent suitably.

  Examples of the plasticizer include various plasticizers and waxes such as dibutyl phthalate (DBP), dioctyl phthalate (DOP), and tricresyl phosphate, and examples of the processing aid include fatty acids such as stearic acid. These plastic components are preferably blended at a ratio of 5 parts by mass or less with respect to 100 parts by mass of the rubber component. This is to prevent bleeding when forming the oxide film and contamination of the photoconductor when the printer is mounted or operated. In view of this purpose, it is most preferable to use a polar wax.

  Examples of the deterioration preventing agent include various antiaging agents and antioxidants. In the case of using an antioxidant, it is preferable to appropriately select the blending amount so that the formation of an oxide film on the surface layer portion to be applied as desired proceeds efficiently.

Examples of the filler include powders such as zinc oxide, silica, carbon, carbon black, clay, talc, calcium carbonate, magnesium carbonate, and aluminum hydroxide. The mechanical strength and the like can be improved by blending the filler.
The addition amount of the filler is preferably 60 parts by mass or less, and more preferably 50 parts by mass or less with respect to 100 parts by mass of the rubber component. The weakly conductive carbon black or alumina also serves as a filler.

  Examples of the scorch inhibitor include N-cyclohexylthiophthalimide, phthalic anhydride, N-nitrosodiphenylamine, 2,4-diphenyl-4-methyl-1-pentene, and the like. Of these, N-cyclohexylthiophthalimide is preferably used. These may be used alone or in combination. The amount of the scorch inhibitor added is preferably 0.1 parts by mass or more and 5 parts by mass or less, and more preferably 0.1 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the rubber component.

The semiconductive roll of the present invention has a dielectric loss tangent of 0.1 to 1.8 when an AC voltage is applied at a voltage of 5 V and a frequency of 100 Hz, and can impart high chargeability to the toner. Sex can be sustained.
The semiconductive roll of the present invention has a roll electric resistance of about 10 ⁵ to 10 ⁷ Ω at an applied voltage of 100V.

  In the semiconductive roll of the present invention, the adhesion to the toner is reduced, and the toner can be moved by an electrostatic force (Coulomb force) without waste. As a result, for example, when the semiconductive roll of the present invention is incorporated in a printer as a developing roll, the transmission density of the printed matter does not decrease even when 2,000 images of 5% printing are printed. That is, when the transmission density of the printed material of the first black solid image is C0 and the printed density of the black solid image printed after printing 2,000 sheets with 5% printing is C2000, C2000 / C0 ≧ 1.

"Examples 1-8, Comparative Examples 1-3"
The compounding materials shown in Table 1 (the values in the table indicate parts by mass) are kneaded with a Banbury mixer, and then extruded into a tube shape with an outer diameter of 22 mm and an inner diameter of 9 to 9.5 mm using a rubber extruder. did. The tube is attached to a φ8 mm shaft for vulcanization, vulcanized at 160 ° C. for 1 hour in a vulcanizing can, and then attached to a φ10 mm shaft coated with a conductive adhesive in an oven at 160 ° C. Glued. Thereafter, the end portion was cut and formed by traverse polishing with a cylindrical polishing machine, followed by mirror polishing as finish polishing to finish the surface roughness Rz to 3 to 5 μm. The surface roughness Rz was measured according to JIS B 0601 (1994). As a result, a semiconductive roll having a diameter of 20 mm (tolerance 0.05) was obtained.

  The roll surface was washed with water and then irradiated with ultraviolet rays to form an oxide layer on the surface layer portion. This uses an ultraviolet irradiator ("PL21-200" manufactured by Sen Special Light Source Co., Ltd.), and the distance between the roll and the ultraviolet lamp is 10 cm, and ultraviolet rays (wavelengths 184.9 nm and 253.7 nm) are emitted every 90 degrees in the circumferential direction. Irradiation was performed for 5 minutes, and the roll was rotated four times by 90 degrees to form an oxide film on the entire circumference of the roll (360 degrees).

The following components were used as constituent components in the semiconductive rolls of the examples and comparative examples.
(A) Rubber component, chloroprene rubber; “Shoprene WRT” manufactured by Showa Denko K.K.
・ Epichlorohydrin copolymer: “Epion ON301” manufactured by Daiso Corporation
EO (ethylene oxide) / EP (epichlorohydrin) / AGE (allyl glycidyl ether) = 73 mol% / 23 mol% / 4 mol%
-Polyether copolymer: “Zeospan ZSN8030” manufactured by Nippon Zeon Co., Ltd.
EO (ethylene oxide) / PO (propylene oxide) / AGE (allyl glycidyl ether) = 90 mol% / 4 mol% / 6 mol%

(B) Other components: Titanium oxide; “Kronos KR310” manufactured by Titanium Industry Co., Ltd.
The main component is a specific gravity of 4.2 and a particle size of 0.3 to 0.5 μm.
・ Weak electric carbon black: “Asahi # 8” manufactured by Asahi Carbon Co., Ltd.
Average primary particle size 120 nm, DBP oil absorption 29 ml / 100 g,
Iodine adsorption 14 mg / g
-Hydrotalcite (acid acceptor); "DHT-4A-2" manufactured by Kyowa Chemical Industry Co., Ltd.
・ Powder sulfur (vulcanizing agent)
・ Ethylenethiourea (vulcanizing agent); “Axel 22-S” manufactured by Kawaguchi Chemical Industry Co., Ltd.

  The following characteristic measurements were performed on the semiconductive rolls of the Examples and Comparative Examples. The results are shown in Table 1.

"Measurement of roll electrical resistance"
As shown in FIG. 2, the toner conveying portion 1 through the core metal 2 is abutted and mounted on the aluminum drum 13, and the tip of the lead wire of the internal resistance r (100Ω) connected to the + side of the power source 14 is connected to the aluminum drum 13. The measurement was performed by connecting the tip of a conductive wire connected to one end surface and connected to the negative side of the power source 14 to the other end surface of the toner transport unit 1.
A voltage applied to the internal resistance r of the electric wire was detected and used as a detection voltage V. Assuming that the applied voltage is E in this apparatus, the roll electrical resistance R is R = r × E / (V−r), but this time the term −r is regarded as very small and R = r × E / V. In a state where a load F of 500 g is applied to both ends of the core metal 2 and rotated at 30 rpm, 100 detection voltages V when the applied voltage E is 100 V are measured for 4 seconds, and R is calculated by the above formula. The measurement was performed under constant temperature and humidity conditions of a temperature of 23 ° C. and a relative humidity of 55%.
In the table, log100R is described.

"Measurement of dielectric loss tangent"
As shown in FIG. 3, an AC voltage having a frequency of 100 Hz to 100 kHz is applied to the toner transport unit 1 using a metal plate 53 on which the toner transport unit 1 is placed and the cored bar 2 as electrodes, and an LCR meter (Ando Electric ( R (resistance) component and C (capacitor) component were separated and measured by “AG-4431B” manufactured by Co., Ltd. From the values of R and C, the dielectric loss tangent was obtained by the following equation. The measurement was performed under constant temperature and humidity conditions of a temperature of 23 ° C. and a relative humidity of 55%.
Dissipation factor (tan δ) = G / (ωC), G = 1 / R
In this way, the dielectric loss tangent is a value obtained as G / ωC when the electrical characteristics of one roll are modeled as two types of parallel equivalent circuits of the resistance component and the capacitor component of the roll. In this embodiment, the dielectric loss tangent is a value when an AC voltage is applied at a voltage of 5 V and a frequency of 100 Hz. The reason why a voltage as small as 5 V is applied is that the toner behaves very close to the voltage fluctuation that occurs when the toner is transferred from, for example, the developing roll to the next photosensitive member.
In this embodiment, the dielectric loss tangent is adjusted to about 0.5 to 1.0.

"Evaluation of toner adhesion of semiconductive roll"
In order to investigate the adhesion between the semiconductive roll and the toner, each semiconductive roll of Examples and Comparative Examples was mounted as a developing roll on a commercially available laser printer (commercial printer using a non-magnetic one-component toner). The performance evaluation was performed using the change in the amount of toner output as an image, that is, the change in the amount of toner layer on the printed material as an index. In addition, the measurement of the toner lamination amount on the printed material can be substituted by the measurement of the transmission density as described below.
Specifically, a black solid image was printed, and the transmission density was measured with a reflection transmission densitometer (TECHSON's “Tessicon densitometer RT120 / light table LP20”) at any five points on the obtained printed matter. The average value was defined as an evaluation value (represented as “C0” in the table).
Further, for black solid images printed after printing 2,000 sheets with 5% printing, the transmission density was measured in the same manner as described above, and the average value was used as the evaluation value (indicated in the table as “C2000”). The reason why the transmission density after printing 2,000 sheets was measured is that the running-in operation is usually terminated at about 2,000 sheets.
The concentration change rate (%) = C2000 / C0 was calculated from the obtained value.

"Evaluation of toner charge"
In order to examine whether the change in the toner charge amount has an influence on the change in the transmission density of the printed matter measured as described above, the following toner charge amount was evaluated.
Specifically, after printing a solid white image (blank paper), the cartridge is removed from the laser printer, and a suction-type charge amount measuring device (Q / M METER Model manufactured by Trek Co., Ltd.) is applied from above to the developing roll mounted on the cartridge. 210HS-2 "), the toner was sucked, and the charge amount (μC) and the toner weight (g) were measured. The amount of static electricity per weight was calculated as the toner charge amount (μC / g) (in the table, expressed as “T0”). That is, toner charge amount (μC / g) = charge amount (μC) / toner weight (g).
Further, 2,000 white solid images (white paper) were printed, and then the toner charge amount (represented as “T2000” in the table) was measured in the same manner as described above.

Generally, it is generally known that when toner is used, the toner charge amount decreases, and as a result, the toner lamination amount on the printed material, that is, the transmission density of the printed material increases. This is because the charge amount of the toner fills the potential difference between the developing roll and the photoreceptor, and the potential difference is proportional to the charge amount of the toner, that is, the toner charge amount (μC / g) × the toner weight (g). Therefore, the principle is that if the toner charge amount decreases as long as the potential difference between the developing roll and the photosensitive member is constant, the toner weight increases.
However, in Comparative Examples 1 and 2, although the charge amount of the toner is slightly decreased, the transmission density of the printed matter is lowered rather than increased. It was found that this was because a part of the toner adhered to the developing roll.
On the other hand, in Examples 1 to 7, the transmission density of the printed matter was increased, and it was confirmed that the phenomenon of toner adhesion to the developing roll as seen in Comparative Examples 1 and 2 did not occur.

It is the schematic of the semiconductive roll of this invention. It is a figure which shows the measuring method of the roll electrical resistance of a semiconductive roll. It is a figure which shows the measuring method of the dielectric loss tangent of a semiconductive roll. It is a figure which shows the measuring method of the friction coefficient of a semiconductive roll.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Toner conveyance part 2 Core metal 3 Seal part 4 Toner 10 Semiconductive roll

Claims (7)

  A semiconductive roll having a toner conveying portion, wherein the toner conveying portion has at least an outermost layer formed of a resin or rubber, and the resin or rubber includes at least a resin or rubber having a chlorine atom, and further contains chlorine. A semiconductive roll comprising titanium oxide at a ratio of 3 to 60 parts by mass with respect to 100 parts by mass of resin or rubber having atoms.   The semiconductive roll according to claim 1 having ionic conductivity.   The semiconductivity according to claim 1 or 2, wherein the resin or rubber further contains a dielectric loss tangent adjusting agent, and has a dielectric loss tangent of 0.1 to 1.8 when an AC voltage is applied at a voltage of 5 V and a frequency of 100 Hz. Sex roll.   The semiconductive roll according to any one of claims 1 to 3, wherein an oxide film is formed on an outermost surface.   The semiconductive roll according to any one of claims 1 to 4, comprising at least a chloroprene rubber as the rubber having a chlorine atom.   The semiconductive roll according to any one of claims 1 to 5, comprising at least an epichlorohydrin copolymer as the rubber or resin having a chlorine atom.   The semiconductive roll according to any one of claims 1 to 6, which is a developing roll used in a developing apparatus using a non-magnetic one-component toner in an image forming mechanism of an electrophotographic apparatus.

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