JP2016188910A - Conductive roll for electrophotographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive roll for an electrophotographic apparatus, which has a conductive rubber elastic layer that has a lower hardness and a smaller compression set compared to conventional products.SOLUTION: A conductive roll 10 for an electrophotographic apparatus includes a shaft 12 and a conductive rubber elastic layer 14 disposed on an outer circumference of the shaft 12. The conductive rubber elastic layer 14 comprises a polar rubber, a nonpolar rubber and a dispersant. The polar rubber is at least one of nitrile rubber, hydrin rubber and chloroprene rubber. The nonpolar rubber is at least one of isoprene rubber, hydrogenated isoprene rubber and natural rubber. The dispersant is at least one of a polymer having a block made of a nitrile rubber component and a block made of an isoprene rubber component, modified natural rubber and modified isoprene rubber.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive roll for electrophotographic equipment.

  In electrophotographic apparatuses such as copying machines, printers, and facsimiles that employ an electrophotographic system, conductive rolls such as a charging roll, a developing roll, a transfer roll, and a toner supply roll are disposed around the photosensitive drum. As an electroconductive roll, what has an electroconductive rubber elastic body layer in the outer periphery of a shaft is known.

JP 2008-250101 A

  In Patent Document 1, a structure in which a nonpolar rubber material is dispersed as an island phase in a continuous phase made of a polar rubber material of a conductive rubber elastic body layer has an excellent low sag while exhibiting an excellent low hardness. It is planned. However, for example, in the developing roll, the stress applied to the toner is further reduced, the toner is more difficult to break down, and the life of the image quality is further extended. From the standpoint of extending the life, the conductive rubber elastic body layer is required to have a lower hardness and a lower level than before.

  The problem to be solved by the present invention is to provide a conductive roll for an electrophotographic apparatus having a conductive rubber elastic body layer having a lower hardness and a lower sag than before.

  In order to solve the above problems, a conductive roll for an electrophotographic apparatus according to the present invention includes a shaft body and a conductive rubber elastic body layer disposed on an outer periphery of the shaft body, and the conductive rubber elastic body layer. Contains a polar rubber, a nonpolar rubber, a dispersant, the polar rubber is at least one of nitrile rubber, hydrin rubber and chloroprene rubber, and the nonpolar rubber is isoprene rubber, hydrogenated isoprene rubber and It is at least one of natural rubber, and the dispersant is at least one of a polymer having a block made of a nitrile rubber component and a block made of an isoprene rubber component, a modified natural rubber, and a modified isoprene rubber. Is a summary.

  The conductive rubber elastic layer preferably has a continuous phase made of the polar rubber and a continuous phase or a dispersed phase made of the nonpolar rubber. The content of the dispersant is preferably in the range of 0.1 to 20 parts by mass with respect to a total of 100 parts by mass of the polar rubber and the nonpolar rubber. The dispersant is preferably at least one of epoxidized natural rubber and epoxidized isoprene rubber. It is preferable that the continuous phase made of the polar rubber contains more conductive agent than the continuous phase or the dispersed phase made of the nonpolar rubber. The content ratio of the polar rubber and the nonpolar rubber is preferably in the range of 20:80 to 90:10 by mass ratio.

  According to the conductive roll for electrophotographic equipment according to the present invention, the polar rubber and the nonpolar rubber of the conductive rubber elastic body layer cannot be obtained by simply blending the polar rubber and the nonpolar rubber with the dispersant. Low hardness and low sag are exhibited.

  In the conductive rubber elastic body layer, when the phase made of nonpolar rubber is the dispersed phase with respect to the continuous phase made of polar rubber, the continuous phase made of polar rubber is easily connected in the thickness direction of the conductive rubber elastic body layer. Therefore, it is easy to improve conductivity. When the content of the dispersant is within the specific range, the hardness is further lowered and the thickness is lowered. When the dispersant is epoxidized natural rubber, the hardness is further lowered and the thickness is lowered. If the continuous phase made of polar rubber contains more conductive agent than the continuous phase or dispersed phase made of nonpolar rubber, it is easy to achieve low hardness while ensuring conductivity. When the content ratio of the polar rubber and the nonpolar rubber is within a specific range, the balance of conductivity, low hardness, and low sag is excellent.

It is the external appearance schematic diagram (a) of the electroconductive apparatus roll for electrophotographic equipment which concerns on one Embodiment of this invention, and its AA sectional view (b).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1A is a schematic external view of a conductive roll for an electrophotographic apparatus according to an embodiment of the present invention, and FIG.

  As shown in FIG. 1, a conductive roll for electrophotographic equipment according to an embodiment of the present invention (hereinafter simply referred to as a conductive roll 10) is disposed on a shaft body 12 and the outer periphery of the shaft body 12. Conductive rubber elastic layer 14.

  The shaft body 12 is not particularly limited as long as it has conductivity. Specific examples include solid bodies made of metal such as iron, stainless steel, and aluminum, and a cored bar made of a hollow body. You may apply | coat an adhesive agent, a primer, etc. to the surface of the shaft body 12 as needed. The adhesive, primer, etc. may be made conductive as necessary.

  The conductive rubber elastic layer 14 is formed of a conductive rubber composition. The conductive rubber composition is vulcanized (crosslinked) with a predetermined vulcanizing agent (crosslinking agent). The conductive rubber elastic layer (conductive rubber composition) 14 contains a polar rubber, a nonpolar rubber, and a dispersant.

  The polar rubber is a rubber having a polar group. Examples of the polar group include a chloro group, a nitrile group, a carboxyl group, and an epoxy group. Specific examples of polar rubbers include hydrin rubber, nitrile rubber (NBR), urethane rubber (U), acrylic rubber (a copolymer of acrylic ester and 2-chloroethyl vinyl ether, ACM), and chloroprene rubber (CR). Etc. Examples of hydrin rubber include epichlorohydrin homopolymer (CO), epichlorohydrin-ethylene oxide binary copolymer (ECO), epichlorohydrin-allyl glycidyl ether binary copolymer (GCO), epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary. A copolymer (GECO) etc. are mentioned. These may be used alone as a polar rubber, or may be used in combination of two or more. Among these, hydrin rubber and nitrile rubber (NBR) are preferable from the viewpoint of lower resistance.

  Nonpolar rubber is rubber that does not have polar groups. Examples of the polar group include a chloro group, a nitrile group, a carboxyl group, and an epoxy group. Nonpolar rubbers include natural rubber (NR), isoprene rubber (IR), hydrogenated isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), butyl rubber (IIR), ethylene-propylene rubber (EPM), Examples thereof include ethylene-propylene-diene terpolymer rubber (EPDM) and silicone rubber (Q). These may be used alone as a nonpolar rubber, or may be used in combination of two or more. Among these, natural rubber and isoprene rubber are preferable from the viewpoint of low hardness and easy reduction.

  Specific examples of the dispersant include a polymer having a block made of a polar rubber component and a block made of a nonpolar rubber component, a modified natural rubber, and a modified isoprene rubber. Examples of the block made of a polar rubber component include a block made of a nitrile rubber component (NBR component). Examples of the block made of a nonpolar rubber component include a block made of an isoprene rubber component (IR component). Examples of such a polymer include a polymer having a block composed of a nitrile rubber component and a block composed of an isoprene rubber component. Examples of the modified natural rubber include epoxidized natural rubber, chlorinated natural rubber, and nitrified natural rubber (acrylonitrile natural rubber). Examples of the modified isoprene rubber include epoxidized isoprene rubber, chlorinated isoprene rubber, nitrified isoprene rubber (acrylonitrile-ized isoprene rubber), maleic acid-modified isoprene rubber, and (meth) acrylic acid-modified isoprene rubber. These may be used alone as a dispersant, or may be used in combination of two or more. Among these, epoxidized natural rubber and epoxidized isoprene rubber are particularly preferable from the viewpoint of being particularly excellent in dispersion effect (fine dispersion effect of nonpolar rubber).

  The non-polar rubber is finely dispersed by the dispersant. As a result, the hardness and elastic recovery rate of the conductive rubber elastic layer 14 linearly improve between the hardness and elastic recovery rate of the polar rubber and the hardness and elastic recovery rate of the nonpolar rubber. As a result, it is possible to satisfy lower hardness and lower sag than in the past while ensuring the low resistance required for the conductive roll for electrophotographic equipment.

  From the standpoint of superiority due to the above effects, a combination of NBR, IR and epoxidized natural rubber is particularly preferable as the combination of polar rubber, nonpolar rubber and dispersant.

  The content of the dispersant is preferably 0.1 parts by mass or more with respect to a total of 100 parts by mass of the polar rubber and the nonpolar rubber from the viewpoint of easily satisfying low hardness and low sag. More preferably, it is 0.5 mass part or more, More preferably, it is 1.0 mass part or more. Moreover, from a viewpoint of ensuring low resistance and low hardness, the amount is preferably 20 parts by mass or less with respect to 100 parts by mass in total of the polar rubber and the nonpolar rubber. More preferably, it is 15 mass parts or less, More preferably, it is 10 mass parts or less.

  The content ratio of the polar rubber and the nonpolar rubber is preferably 20% by mass or more of the polar rubber in the total of both from the viewpoint of easily ensuring low resistance. More preferably, it is 30 mass% or more. Moreover, it is preferable that nonpolar rubber | gum is 10 mass% or more from a viewpoint of being easy to satisfy low hardness and low sag. More preferably, it is 20 mass% or more. Therefore, the content ratio of the polar rubber and the nonpolar rubber is preferably in the range of 20:80 to 90:10 in terms of mass ratio from the viewpoint of excellent balance between conductivity, low hardness, and low sag. . More preferably, it exists in the range of 30: 70-80: 20.

  The conductive rubber elastic layer (conductive rubber composition) 14 contains a conductive agent as necessary from the viewpoint of low resistance and the like. Examples of the conductive agent include ionic conductive agents and electronic conductive agents. As the conductive agent, an ionic conductive agent or an electronic conductive agent added to the conductive rubber elastic layer of the conductive roll for electrophotographic equipment can be used.

  Examples of the ionic conductive agent include quaternary ammonium salts, quaternary phosphonium salts, borates, and surfactants. The content of the ionic conductive agent is preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the polar rubber from the viewpoints of low resistance and bleeding. More preferably, it exists in the range of 0.5-5.0 mass parts.

  Examples of the electronic conductive agent include carbon black, graphite, potassium titanate, iron oxide, conductive titanium oxide, conductive zinc oxide, and conductive tin oxide. The content of the electronic conductive agent is preferably in the range of 1.0 to 20 parts by mass with respect to 100 parts by mass of the polar rubber from the viewpoints of low resistance, low hardness, low sag, and the like. More preferably, it exists in the range of 5.0-15 mass parts.

  The conductive rubber elastic layer (conductive rubber composition) 14 contains a vulcanizing agent (crosslinking agent), a vulcanization accelerator, a vulcanization aid (crosslinking aid) and the like, if necessary. Further, one or more additives such as a bulking agent, a reinforcing agent, a processing aid, an antioxidant, a plasticizer, an ultraviolet absorber, and a lubricant can be contained.

  Examples of the vulcanizing agent (crosslinking agent) include sulfur and peroxide. Among the vulcanizing agents (crosslinking agents), a peroxide is more preferable from the viewpoint of being easily lowered. It is preferable that the compounding quantity of a peroxide exists in the range of 0.5-7 mass parts with respect to a total of 100 mass parts of polar rubber and nonpolar rubber from a viewpoint of being easy to make low. More preferably, it exists in the range of 1.0-5 mass parts.

  In the conductive rubber elastic layer 14, the phase made of polar rubber is preferably a continuous phase from the viewpoint of conductivity. The phase composed of nonpolar rubber may be a continuous phase or a dispersed phase (noncontinuous phase). The dispersed phase is a phase scattered in an island shape in the continuous phase. When the phase made of nonpolar rubber is a dispersed phase, the phase made of polar rubber becomes a continuous phase that is continuous in both the circumferential direction and the thickness direction of the conductive rubber elastic layer 14, so that it is easy to ensure conductivity. . Moreover, when mix | blending a electrically conductive agent from viewpoints, such as electroconductivity and low resistance, it can mix | blend only to the phase which consists of polar rubbers, or can reduce the compounding quantity to the phase which consists of nonpolar rubbers. Thereby, the compounding quantity of the electrically conductive agent for obtaining desired electroconductivity can be decreased. In particular, by reducing the blending amount of the electronic conductive agent, an increase in hardness can be suppressed, and low hardness and low sag can be easily satisfied. Therefore, the phase made of nonpolar rubber is more preferably a dispersed phase.

  In the case of blending a conductive agent from the viewpoint of conductivity, low resistance, etc., it is preferable that the continuous phase made of polar rubber contains more conductive agent than the continuous phase or dispersed phase made of nonpolar rubber. Thereby, it is easy to achieve low hardness while ensuring conductivity.

  In order to make the amount of the conductive agent contained in the phase made of the polar rubber different from the amount of the conductive agent contained in the phase made of the nonpolar rubber, the polar rubber and the conductive agent are previously kneaded, and then the polar rubber containing the conductive agent A conductive rubber composition may be prepared by a method such as kneading a nonpolar rubber containing no conductive agent. Alternatively, a conductive agent is blended in each of the polar rubber and the nonpolar rubber in advance, but after adding a larger amount of the conductive agent to the polar rubber, the polar rubber containing more conductive agent and the nonpolar rubber containing the conductive agent are kneaded. What is necessary is just to prepare a conductive rubber composition by methods, such as doing.

By using a predetermined conductive rubber composition, the conductive rubber elastic layer 14 is excellent in conductivity, and satisfies low hardness and low sag. From the viewpoint of conductivity, the resistance value of the conductive rubber elastic layer 14 is preferably in the range of 1.0 × 10 ^{3 to} 1.0 × 10 ⁹ Ω. Moreover, it is preferable that MD-1 hardness of the electroconductive rubber elastic body layer 14 is 47 or less from a viewpoint of lower hardness than before. More preferably, it is 45 or less. From the viewpoint of lowering than before, the elastic recovery rate of the conductive rubber elastic layer 14 is preferably more than 80%. More preferably, it is 85% or more. The MD-1 hardness is measured using a cantilever-type leaf spring type spring type hardness tester (manufactured by Kobunshi Keiki Co., Ltd., “Micro Rubber Hardness Tester MD-1 Type”). The MD-1 hardness measurement value is a value measured with a rubber thickness of 1 to 2 mm. The elastic recovery rate is measured using a microhardness meter (Fischer, Fischerscope H100C) in accordance with ISO14577-1.

  The thickness of the conductive rubber elastic layer 14 is not particularly limited, but is usually formed to be about 0.1 to 10 mm, preferably 1 to 5 mm. The conductive rubber elastic layer 14 may be a solid non-foamed material or a sponge-like foamed material.

  The conductive roll 10 can be manufactured as follows, for example. First, an adhesive composition is applied to the outer periphery of the shaft body 12 as necessary. Next, the conductive rubber composition is formed into a layer on the outer periphery of the applied adhesive composition. The conductive rubber composition can be molded by extrusion molding or mold molding. The conductive rubber composition is crosslinked and cured by heating at the time of extrusion molding or mold molding. Thereby, the electroconductive roll 10 which has the electroconductive rubber elastic body layer 14 in the outer periphery of the shaft body 12 is obtained.

  On the outer periphery of the conductive rubber elastic layer 14, the surface characteristics of the conductive roll 10 that protect the surface of the conductive rubber elastic layer 14 as necessary (low friction, releasability, chargeability, etc.) A surface layer may be formed for the purpose of imparting. Further, an intermediate layer such as a resistance adjusting layer for adjusting the resistance of the entire conductive roll 10 may be formed under the surface of the outer periphery of the conductive rubber elastic layer 14.

  The main material for forming the surface layer is not particularly limited, and examples thereof include polyamide (nylon) -based, acrylic-based, urethane-based, silicone-based, and fluorine-based polymers. These polymers may be modified. Examples of the modifying group include an N-methoxymethyl group, a silicone group, and a fluorine group.

The surface layer, for imparting conductivity, carbon black, _{graphite, c-TiO 2, c-} ZnO, c-SnO 2 (c- means conductive.), Ion conductive agent (quaternary ammonium salt, Conventionally known conductive agents such as borates and surfactants can be appropriately added. Moreover, you may add various additives suitably as needed.

  In order to form the surface layer, a surface layer forming composition is used. The composition for surface layer formation consists of what contains the said main material, a electrically conductive agent, and the other additive contained as needed. Additives include lubricants, vulcanization accelerators, anti-aging agents, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, foaming agents, fillers, dispersants, antifoaming agents, pigments, release agents. Examples include molds.

  From the viewpoint of adjusting the viscosity, the surface layer-forming composition is an organic solvent such as methyl ethyl ketone, toluene, acetone, ethyl acetate, butyl acetate, methyl isobutyl ketone (MIBK), THF, or DMF, or a water-soluble solution such as methanol or ethanol. A solvent such as a reactive solvent may be included as appropriate.

  The surface layer can be formed by a method such as coating the surface forming composition on the outer periphery of the conductive rubber elastic body layer 14. As a coating method, various coating methods such as a roll coating method, a dipping method, and a spray coating method can be applied. The coated surface layer may be subjected to ultraviolet irradiation or heat treatment as necessary.

The thickness of the surface layer is usually set to 0.01 to 100 μm, 0.1 to 20 μm, or 0.3 to 10 μm. The volume resistivity of the surface layer is usually set to 10 ⁴ to 10 ⁹ Ω · cm, 10 ⁵ to 10 ⁸ Ω · cm, or 10 ⁶ to 10 ⁷ Ω · cm.

  Further, instead of forming the surface layer, the intermediate layer such as the conductive rubber elastic body layer 14 or the resistance adjusting layer may be subjected to surface modification so as to have surface characteristics equivalent to the formation of the surface layer. it can. Surface modification methods include UV or electron beam irradiation, surface layer unsaturated bonds and surface modifiers that can react with halogens, such as isocyanate groups, hydrosilyl groups, amino groups, halogen groups, thiol groups, etc. Examples thereof include a method of contacting with a compound containing a reactive group.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to this structure.

Details of the materials used are shown below.
(Polar rubber)
Nitrile rubber (NBR): JSR "N237H"
・ Hydrin rubber (ECO): “Hydrin T3106” manufactured by Zeon Corporation
・ Chloroprene Rubber (CR): [Showa Denko “Shoprene GW”]
(Non-polar rubber)
Isoprene rubber (IR): “JSR IR2200” manufactured by JSR
・ Natural rubber (NR): “RSS1”
Hydrogenated isoprene (hydrogenated IR): “L-IR290” manufactured by Kuraray Co., Ltd.
(Dispersant)
Dispersant (1): Reaction product of maleic acid-modified IR and both terminal amine-modified NBR Dispersant (2): Block copolymer of NBR and IR Dispersant (3): Epoxy-modified NR (Muang Mai Guthrie “EPOXYPRENE50” manufactured by Public Company Limited)
Dispersant (4): Epoxidized modified IR synthetic product Dispersant (5): Nitrile modified NR synthetic product

(Conductive agent)
・ Ionic conductive agent: Tetrabutylammonium bromide, “TBAB-100” manufactured by Lion Akzo Co., Ltd.
・ Carbon black (electronic conductive agent): Denka Black manufactured by Denki Kagaku Kogyo
(Vulcanizing agent, vulcanization accelerator)
・ Peroxide: “Park Mill D40” manufactured by NOF Corporation
・ Sulfur (vulcanizing agent)
・ Vulcanization accelerator (1): Sulfenamide-based, “Noxeller MSA” manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Vulcanization accelerator (2) Thiuram, “Noxeller TOT-N” manufactured by Ouchi Shinsei Chemical Co., Ltd.

(Examples 1-17, Comparative Examples 1-6)
<Preparation of conductive rubber composition>
In the composition (mass ratio) shown in Tables 1 and 2, blend polar rubber, nonpolar rubber, dispersant, conductive agent, vulcanizing agent (crosslinking agent), vulcanization accelerator, and stir and mix with a stirrer. A conductive rubber composition was prepared.

<Preparation of conductive roll>
A core metal (diameter 6 mm) is set on the central axis of a molding die having a cylindrical molding cavity of 9 mm in diameter, and a conductive rubber composition is injected into the molding die, followed by heating and crosslinking at 160 ° C. for 30 minutes. Then, cooling and demolding were performed to form a conductive rubber elastic body layer having a thickness of 1.5 mm on the outer periphery of the cored bar. This produced the electroconductive roll.

  About the electroconductive rubber elastic body layer of each obtained electroconductive roll, the elastic recovery rate, MD-1 hardness, and resistance value were measured. In addition, product characteristics such as setability, durability fogging, and image density were evaluated. The setability is affected by the sagability of the conductive rubber elastic layer. The durability fogging property is affected by the hardness of the conductive rubber elastic body layer. The image density is affected by the resistance value (conductivity) of the conductive rubber elastic layer.

(Elastic recovery rate)
In accordance with ISO14577-1, the surface of the conductive rubber elastic body layer was measured under the following measurement conditions using a micro hardness meter (Fischer Scope H100C, manufactured by Fischer), and ηIT [%] was determined. That is, when a microhardness meter is used and the indenter is pushed into the material surface with a constant test load, the total mechanical work Wtotal of the dent shown during the indentation work is very small as the plastic deformation work Wplast of the dent. Only part is consumed. When the test load is unloaded, the remaining part is released as the elastic return deformation work Welast of the recess. If this mechanical work is defined as W = ∫Fdh, the relationship is as follows. The elastic recovery rate was set to 85% or higher, and less than 85% was set to high.
ηIT [%] = Welast / Wtotal
However, Wtotal = Welast + Wplast
<Measurement conditions>
Indenter: Square-angled diamond indenter with a face angle of 136 ° Initial load: 0 mN
Maximum indentation load: 20mN (constant load)
Maximum load arrival time: 0.25 to 10 sec
Maximum load holding time: 5 sec
Drawing time: 0.25-10sec
Measurement temperature: 25 ° C

(MD-1 hardness (micro rubber hardness))
Conductive rubber of each conductive roll held using a cantilever-type leaf spring type spring type hardness tester (manufactured by Kobunshi Keiki Co., Ltd., “Micro Rubber Hardness Tester MD-1”) Measured by bringing the tip of the needle of the hardness tester into contact with the surface of the central portion in the axial direction of the elastic layer, further pressing the tester vertically with a load of 33.85 g, and immediately reading the scale. did. The MD-1 hardness was 45% or less as low hardness and over 45% as high hardness.

(Resistance value)
With the both ends of the conductive roll pressed against the metal roll (diameter: 30 mm) with a predetermined load, the conductive roll was rotated by rotating the metal roll at a predetermined rotation speed. While maintaining this state (while rotating both the metal roll and the conductive roll), a voltage of 300 V is applied between the ends of the conductive roll and the metal roll, the flowing current value is measured, and the electric resistance value (roll Resistance: Ω) was obtained. The case where the volume resistivity is 1 × 10 ⁹ Ω exceeds a high resistance, and the case of the range of ^{1 × 10 3 Ω~1 × 10 9} Ω and low resistance.

(Set property)
The conductive roll was assembled to the cartridge, sealed, and left in a normal temperature and humidity environment for 14 days. Thereafter, the image was printed in a normal temperature and humidity environment. The case where a streak-like defect was seen in the drawing was judged as “failed” “x”, and the case where it was not seen was judged as “passed”. Moreover, the roundness of the conductive rubber elastic body layer was measured with Roncom, and the amount of sag from the dent amount from the roundness was measured. A case where the amount of sag was 5 μm or less was regarded as low, and a case where the amount was more than 5 μm was regarded as high. Of the acceptable “◯” in the setting property, the case where the amount of sag was 2 μm or less was particularly good “◎”.

(Durable fogging)
A conductive roll was assembled in the cartridge, and a white solid image was printed. The density was measured with a white photometer, and if it was within the range of 1.40 to 1.46 at any nine points, it was judged as “good”, and if it was out of the range, it was judged as “poor”. Among the “◯” with good durability fogging, those with white light intensity in the range of 1.43 to 1.45 at any nine points were particularly good “「 ”.

(Image density)
A conductive roll was assembled in the cartridge, and a black solid image was printed. The density was measured with a white photometer, and if it was within the range of 1.0 to 2.0 at any nine points, it was judged as “good”, and if it was out of the range, it was judged as “bad”. Among the images with good image density “◯”, those with white light intensity in the range of 1.3 to 1.6 at any 9 points were rated particularly good “「 ”.

  In Comparative Examples 1 to 3, nonpolar rubber and dispersant are not blended with polar rubber. That is, the rubber is composed only of polar rubber. For this reason, even if the blending amount of the vulcanizing agent is adjusted, it is not possible to satisfy a high level of low hardness and low sag than before. For this reason, it is impossible to achieve both setability and durability fogging. In Comparative Examples 4 to 5, the polar rubber and the dispersant are not blended with the nonpolar rubber. That is, the rubber is made of only nonpolar rubber. For this reason, even if it adjusts the compounding quantity of a electrically conductive agent, after setting it as low resistance, the low hardness and low sag of a level higher than before cannot be satisfied. For this reason, it is impossible to achieve both image density, setability and durability fogging. In Comparative Example 6, nonpolar rubber is blended with polar rubber, but no dispersant is blended. For this reason, the dispersibility of the polar rubber and the nonpolar rubber is poor, and it is not possible to satisfy the low hardness and low sag that are higher than the conventional level. For this reason, it is impossible to achieve both setability and durability fogging.

  On the other hand, according to the examples, since the non-polar rubber and the dispersant are blended with the polar rubber, the dispersibility of the polar rubber and the non-polar rubber is good, low resistance and low hardness of a higher level than before. And I am satisfied with the low setting. For this reason, it is excellent in all of setability, durable fog, and image density.

  Among the dispersants, the epoxy-modified NR (Example 3) can be particularly low in hardness and low, compared with the case where other dispersants (Examples 1, 2, 4, 5) are used. And it is more excellent in terms of setability and durability. Among non-polar rubbers, IR (Example 3) can have a lower hardness and lower setting than NR (Example 6), and is superior in terms of setability. Among polar rubbers, NBR (Example 3) can have a lower hardness and lower sag than ECO (Example 7) and CR (Example 8), and is more excellent in terms of setability. According to Examples 3 and 10 to 12, when the blending amount of the dispersant increases, the hardness tends to increase. According to Example 13, when an electronic conductive agent (carbon black) is added to improve conductivity, hardness and sag tend to deteriorate. According to Examples 14-15, when there is much polar rubber, there exists a tendency for hardness and sag to deteriorate, and when there is little polar rubber, there exists a tendency for resistance to rise. According to Examples 16 to 17, it is understood that the peroxide crosslinking is lower than the sulfur crosslinking.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said Example at all, A various change is possible in the range which does not deviate from the summary of this invention.

DESCRIPTION OF SYMBOLS 10 Conductive roll 12 for electrophotographic apparatuses Shaft body 14 Conductive rubber elastic body layer

Claims (6)

A shaft body, and a conductive rubber elastic body layer disposed on the outer periphery of the shaft body,
The conductive rubber elastic layer contains a polar rubber, a nonpolar rubber, a dispersant,
The polar rubber is at least one of nitrile rubber, hydrin rubber and chloroprene rubber;
The nonpolar rubber is at least one of isoprene rubber, hydrogenated isoprene rubber and natural rubber;
The conductive roll for electrophotographic equipment, wherein the dispersant is at least one of a polymer having a block made of a nitrile rubber component and a block made of an isoprene rubber component, a modified natural rubber, and a modified isoprene rubber. .   The electroconductive rubber electroconductive device according to claim 1, wherein the conductive rubber elastic body layer has a continuous phase made of the polar rubber and a continuous phase or a dispersed phase made of the nonpolar rubber. roll.   3. The electron according to claim 1, wherein a content of the dispersant is in a range of 0.1 to 20 parts by mass with respect to 100 parts by mass in total of the polar rubber and the nonpolar rubber. Conductive roll for photographic equipment.   The electroconductive roll for electrophotographic equipment according to any one of claims 1 to 3, wherein the dispersant is at least one of epoxidized natural rubber and epoxidized isoprene rubber.   The continuous phase made of the polar rubber contains more conductive agent than the continuous phase or the dispersed phase made of the non-polar rubber. The electroconductive roll for electrophotographic equipment as described in 2.   6. The electrophotographic apparatus according to claim 1, wherein a content ratio of the polar rubber to the nonpolar rubber is in a range of 20:80 to 90:10 in terms of parts by mass. Conductive roll.

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