JP4267313B2 - Conductive roller and manufacturing method thereof - Google Patents

Description

【００４５】
【発明の効果】
本発明によれば、少なくともフッ素化オレフィン樹脂とアクリル樹脂とを含む塗布液を塗布し、塗布液に用いられる溶媒の沸点未満の温度で乾燥した後、さらにフッ素化オレフィン樹脂の融点以上の温度で乾燥するので、フッ素化オレフィンが溶融して抵抗調整層の表面粗さを小さくするとともに、フッ素化オレフィンが再配列して表面エネルギを低減することができ、導電性ローラの最外層を形成する抵抗調整層の表面エネルギと表面粗さ（Ｒ _Ｚ ）とが、好適な範囲となる。このようにして耐汚れ性に優れた導電性ローラを製造することができる。
また本発明によれば、塗布液に用いられる溶媒がメチルエチルケトンである。そして、塗布液に用いられる溶媒の沸点未満の温度である５０℃で乾燥し、その後さらにフッ素化オレフィン樹脂の融点以上の温度である１２０℃以上の温度で乾燥して抵抗調整層を形成するのが好ましい。これによって、抵抗調整層の表面エネルギと表面粗さ（Ｒ _Ｚ ）とが、確実に好適な範囲となる。
また本発明によれば、導電性ローラの最外層を構成する抵抗調整層には、フッ素化オレフィン樹脂とアクリル樹脂とが含まれる。フッ素化オレフィン樹脂は、抵抗調整層の表面エネルギを低減し、アクリル樹脂は、抵抗調整層の膜強度を向上し導電弾性層との密着性を向上するので、トナーの付着を抑制して耐汚れ性に優れるとともに耐久性に優れた導電性ローラを得ることができる。また導電性ローラの最外層を形成する抵抗調整層の表面エネルギと表面粗さ（Ｒ _Ｚ ）とが、好適な範囲になるように設定されるので、一層耐汚れ性に優れた導電性ローラが実現される。
【００４６】
また本発明は、前記の導電性ローラが、放電または電荷注入によりトナーを帯電させるトナー帯電ローラとして設けられることを特徴とする現像装置である。
【００４７】
本発明に従えば、耐汚れ性に優れた導電性ローラがトナー帯電ローラとして用いられるので、放電によって帯電されるトナーの帯電量が安定し、安定した品質のトナー画像を得ることができる。
【図面の簡単な説明】
【図１】本発明の実施の一形態である導電性ローラ１の構成を簡略化して示す断面図である。
【図２】本発明の他の実施の形態である現像装置３０の構成を簡略化して示す図である。
【符号の説明】
１ 導電性ローラ
２ 軸体
３ 導電弾性層
４ 抵抗調整層
３０ 現像装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a conductive roller used in an electrophotographic apparatus, and more particularly to a conductive roller suitably used for a toner charging roller.
[0002]
[Prior art]
In an electrophotographic image forming apparatus, an electrostatic latent image formed on the surface of a photoreceptor is visualized as a toner image by a developing device. Various methods are used for developing an electrostatic latent image as a toner image. For example, in the two-component development system, magnetic powder as a carrier and nonmagnetic toner are agitated and mixed to frictionally charge the toner, and the electrostatic force causes the toner to adhere to the magnetic powder, and the magnetic powder is a magnet provided on the developing roller. Since the magnetic force of the piece attracts the developing roller, the toner is held by the developing roller. In the one-component development method using only magnetic toner or non-magnetic toner, the toner is charged by friction between the developing roller and / or the toner thinning blade and the toner, and the electrostatic force holds the toner on the surface of the developing roller. Is done.
[0003]
Among the development methods described above, particularly in the one-component development method using a non-magnetic toner, since there is no magnetic binding force on the toner, the toner is rubbed in a stable state with the developing roller and / or the toner thinning blade. There is a problem that charging with respect to the toner tends to be unstable.
[0004]
One of the prior arts that attempt to solve such problems is to charge a non-magnetic one-component developing toner with a toner charging roller and discharge the toner without depending on unstable frictional charging alone. In other words, a thin layer of toner is stably formed on the surface of the developing roller to prevent image fogging (see, for example, Patent Document 1). However, since the toner charging roller is always in contact with the toner, the toner charging roller surface is contaminated, and the discharge becomes unstable due to the contamination. There is a problem that the performance is deteriorated and an image having a stable quality cannot be obtained.
[0005]
Fluorine-based material that reduces the surface energy of the material that forms the roller surface, as a method to reduce contamination of the roller surface used in electrophotographic devices such as a roller that charges the surface of the photoreceptor, although it is different from a roller that charges toner It is known to use these materials (see, for example, Patent Document 2).
[0006]
However, even if a fluorine-based material is used as the outermost layer material of the roller, the use as a surface modifier simply causes the low molecular components in the fluorine-based material to exude from the surface of the roller. There is a problem that the photosensitive member is contaminated, and there is a problem that desired stain resistance cannot be realized unless the manufacturing conditions, particularly the drying conditions after forming the outermost layer of the roller, are appropriate.
[0007]
[Patent Document 1]
JP 11-119546 A [Patent Document 2]
Japanese Patent Laid-Open No. 2002-251053
[Problems to be solved by the invention]
An object of the present invention is to provide a conductive roller suitable for a toner charging roller that is excellent in stain resistance, can stably discharge continuously, and can impart stable charging to toner, and a method for manufacturing the same. That is.
[0011]
[Means for Solving the Problems]
The present invention provides a shaft body having conductivity, a conductive elastic layer made of an elastic body having conductivity, provided on the outer peripheral surface of the shaft body, provided on the outer periphery of the conductive elastic layer, and at least a fluorinated olefin resin. And a resistance adjusting layer having a surface roughness of 3.0 μm or less in terms of 10-point average roughness (R _Z ) and a surface energy of 40 dynes / cm or less. And
Preparing the shaft,
Forming the conductive elastic layer on the outer peripheral surface of the shaft body;
Applying a coating liquid in which at least a fluorinated olefin resin and an acrylic resin are dissolved or dispersed in a solvent to the outer periphery of the conductive elastic layer,
Drying at a temperature below the boiling point of the solvent used in the coating solution,
Thereafter, the resistance adjusting layer is formed by further drying at a temperature equal to or higher than the melting point of the fluorinated olefin resin .
[0012]
According to the present invention, a coating liquid containing at least a fluorinated olefin resin and an acrylic resin is applied, dried at a temperature lower than the boiling point of the solvent used in the coating liquid, and further at a temperature equal to or higher than the melting point of the fluorinated olefin resin. Since it dries, the fluorinated olefin melts to reduce the surface roughness of the resistance adjustment layer, and the fluorinated olefin rearranges to reduce the surface energy, thereby forming the outermost layer of the conductive roller. The surface energy and the surface roughness (R _Z ) of the adjustment layer are in a suitable range . In this way, a conductive roller excellent in stain resistance can be manufactured.
In the present invention, the solvent used in the coating solution is methyl ethyl ketone,
Dry at 50 ° C., which is a temperature lower than the boiling point of the solvent used in the coating solution,
Thereafter, the resistance adjusting layer is formed by further drying at a temperature of 120 ° C. or higher, which is a temperature higher than the melting point of the fluorinated olefin resin.
According to the present invention, the surface energy and the surface roughness (R _Z ) of the resistance adjustment layer are surely within a preferable range.
Further, the present invention is a conductive roller manufactured by the method for manufacturing the conductive roller,
A shaft body having conductivity;
A conductive elastic layer provided on the outer peripheral surface of the shaft body and made of a conductive elastic body;
Further provided on the outer periphery of the conductive elastic layer, including at least a fluorinated olefin resin and an acrylic resin, the surface roughness is 3.0 μm or less in terms of 10-point average roughness (R _Z ), and the surface energy is 40 dynes / cm or less. And a resistance adjusting layer.
According to the present invention, the resistance adjustment layer constituting the outermost layer of the conductive roller includes a fluorinated olefin resin and an acrylic resin. The fluorinated olefin resin reduces the surface energy of the resistance adjustment layer, and the acrylic resin improves the film strength of the resistance adjustment layer and improves the adhesion to the conductive elastic layer. A conductive roller having excellent durability and durability can be obtained. In addition, since the surface energy and the surface roughness (R _Z ) of the resistance adjustment layer forming the outermost layer of the conductive roller are set to be in a suitable range, a conductive roller having further excellent dirt resistance can be obtained. Realized.
[0013]
According to another aspect of the present invention, the conductive roller is provided as a toner charging roller for charging the toner by discharging or charge injection.
[0014]
According to the present invention, since the conductive roller having excellent stain resistance is used as the toner charging roller, the charge amount of the toner charged by the discharge is stabilized, and a stable quality toner image can be obtained.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view showing a simplified configuration of a conductive roller 1 according to an embodiment of the present invention. The conductive roller 1 includes a shaft body 2 having conductivity, a conductive elastic layer 3 provided on the outer peripheral surface of the shaft body 2, and a resistance adjustment layer 4 provided further on the outer periphery of the conductive elastic layer 3. The shaft body 2 has an elongated right circular column shape processed at both ends in order to pivotally support both ends or to fit a drive part, and is made of, for example, a metal member made of plated steel, aluminum alloy, stainless steel, or the like. It is.
[0016]
The conductive elastic layer 3 is formed from a foamed or non-foamed rubber composition containing a conductivity imparting agent. As the rubber component of the foamed or non-foamed rubber composition, acrylonitrile-butadiene rubber (NBR), ethylene-propylene rubber (EPDM), chloroprene rubber (CR), epichlorohydrin rubber and the like are used. These rubber compositions may be used individually by 1 type, and 2 or more types may be mixed and used for them.
[0017]
Carbon black, titanium oxide, tin oxide, zinc oxide, or the like can be used as the conductivity imparting agent. Carbon black is preferably used because of its excellent dispersibility in the rubber composition and excellent reinforcing function. The conductive elastic layer 3 was formed by extruding or press-molding a rubber composition whose conductivity value was adjusted by kneading a conductivity-imparting agent, and formed by heat vulcanization. The conductive elastic layer 3 may contain one or more other vulcanizing agents, vulcanization accelerators, softeners, fillers, processing aids, and the like. The formed conductive elastic layer 3 may be subjected to grinding in order to adjust the dimensions and surface properties.
[0018]
The resistance adjustment layer 4 is formed of a mixture containing at least a fluorinated olefin resin and an acrylic resin. Moreover, carbon black, a titanium oxide, and an ionic conductive agent are contained as needed as an electroconductivity imparting agent. Hereinafter, a method for forming the resistance adjustment layer 4 on the outer periphery of the conductive elastic layer 3 will be described. A solvent, for example, methyl ethyl ketone (MEK: CH ₃ CH ₂ COCH ₃ , boiling point 79.5 ° C.) 45 parts by weight of a fluorinated olefin resin 5 parts by weight, MEK 45 parts by weight of acrylic resin 5 parts by weight The dissolved liquid is mixed to prepare a coating liquid. The fluorinated olefin resin is used to reduce the surface energy of the resistance adjustment layer 4 and reduce the surface roughness. The acrylic resin improves the adhesion with the conductive elastic layer 3, and the resistance adjustment layer 4 Used to improve strength.
[0019]
The prepared coating solution is first coated with a coating solution containing a fluorinated olefin resin and an acrylic resin on the outer periphery of the conductive elastic layer 3 by coating means such as dipping, roll coater, spray coating, etc. In the drying step, the solvent is dried at a temperature lower than 79.5 ° C. of the boiling point of MEK, for example. The reason for limiting the drying temperature in the first drying step immediately after coating will be described.
[0020]
When the fluorinated olefin resin immediately after coating is dissolved in the solvent, when dried at a temperature equal to or higher than the boiling point of the solvent, the fluorinated olefin resin crystallizes and the coating film becomes cloudy, and the fluorinated olefin resin is in the coating film. Aggregates to deteriorate wettability and roughen the surface. Moreover, when it dries at the temperature more than the boiling point of a solvent, a bubble may generate | occur | produce in a coating film or peeling of a coating film may generate | occur | produce by the rapid vaporization of a solvent. Therefore, it is dried at a temperature below the boiling point in order to prevent the occurrence of defects as described above.
[0021]
When the vaporization disappearance of the solvent is completed in the first drying step, the second drying step is followed by drying at a temperature equal to or higher than the melting point of the fluorinated olefin resin (120 ° C. in the present embodiment). The reason for limiting the drying temperature in the second drying step will be described. By heating the solvent to a temperature equal to or higher than the melting point of the fluorinated olefin resin after the vaporization disappears, the fluorinated olefin resin on the surface of the coating and in the vicinity of the surface melts. Arrange them side by side on the surface. Moreover, when the fluorinated olefin resin is melted, the surface of the coating film is smoothed. By this, the wettability of the coating film which is the resistance adjusting layer 4 is improved, and the surface roughness is further reduced. Therefore, in the second drying step, drying is performed at a temperature equal to or higher than the melting point of the fluorinated olefin resin.
[0022]
Thus, the resistance adjustment layer 4 formed on the outermost layer of the conductive roller 1 has a surface roughness of 3.0 μm or less in terms of a ten-point average roughness (R _Z ) defined in Japanese Industrial Standard B0601. The surface energy is 40 dynes / cm or less.
[0023]
The reason for limiting the range of the surface roughness (R _Z ) and the surface energy will be described. If the surface roughness (R _Z ) exceeds 3.0 μm, the toner particles enter the rough concave and convex portions formed on the surface of the resistance adjusting layer 4 and are easily captured and adhered. Accordingly, the surface roughness (R _Z ) is set to 3.0 μm or less.
[0024]
By reducing the surface energy, the triboelectric chargeability with respect to the toner can be lowered, so that the electrical adsorption of the toner to the roller surface can be reduced. Accordingly, the surface energy is set to 40 dynes / cm or less.
[0025]
Such a resistance adjustment layer 4 finely adjusts the resistance value of the conductive roller 1 and also improves the stain resistance by adjusting the surface properties of the conductive roller 1.
[0026]
FIG. 2 is a diagram showing a simplified configuration of the developing device 30 according to another embodiment of the present invention. The developing device 30 shown in FIG. 2 includes the conductive roller 1 according to the embodiment of the present invention as a toner charging roller. The developing device 30 of the present embodiment is used by being mounted in, for example, a cartridge type on a laser printer that is an electrophotographic apparatus. FIG. 2 shows a photoconductor 38 and a charger 39 that constitute a part of the laser printer.
[0027]
The developing device 30 includes a housing 31 that is a hollow container, a developing roller 32 that is rotatably supported by the housing 31, and an axial line that is disposed in parallel to the axial direction of the developing roller 32. A supply roller 33 to be supported, a developing blade 34 that is mounted so that one end 35 is mounted on the housing 31 and a free end 36 that is the other end is in contact with the outer peripheral surface of the developing roller 32, and the developing roller 32 And a toner charging roller 1 that is a conductive roller 1 that is disposed so that the axis is positioned in parallel to the axial direction and is in pressure contact with the developing roller 32.
[0028]
The housing 31 is a hollow container having a substantially rectangular parallelepiped shape made of hard resin or steel, and a non-magnetic one-component developer 37 (developer consisting of one toner component) in the inner space thereof. Called).
[0029]
The supply roller 33 agitates the toner 37 in the housing 31 by rotating around the axis in the direction indicated by the arrow in FIG. 2, conveys the toner 37 by its outer peripheral surface, and supplies the toner 37 to the surface of the developing roller 32. Supply. Further, since the supply roller 33 rotates in a direction opposite to the rotation direction of the developing roller 32, the toner remaining on the surface of the developing roller 32 can be removed after the development is completed.
[0030]
The toner 37 supplied to the surface of the developing roller 32 by the supply roller 33 is frictionally charged by the developing blade 34 in contact with the surface of the developing roller 32. The toner 37 on the surface of the developing roller 32 is further charged by the discharge of the toner charging roller 1 provided downstream of the developing blade 34 in the rotation direction of the developing roller 32. The toner charging roller 1 used at this time has a small surface energy and excellent wettability, and also has a small surface roughness (R _Z ), so that the toner 37 does not unnecessarily adhere to the surface, that is, has a stain resistance. Good roller. Since the toner charging roller 1 can perform a stable discharge continuously for a long time, the charge amount of the toner 37 charged by the discharge is stabilized.
[0031]
An electrostatic latent image formed on the surface of the photoconductor 38 after being uniformly charged by the charger 39 and then exposed to the exposure means (not shown) is converted into the surface of the developing roller 32 by the toner 37 having the appropriate and stable charge amount. Therefore, it is possible to move to the surface of the photosensitive member 38 and develop, so that it is possible to stably form a good quality image.
[0032]
(Example)
Examples of the present invention will be described below. The conductive rollers of Examples and Comparative Examples to be described later are respectively produced, and for each of the produced conductive rollers, the surface energy that is an evaluation index of wettability is measured for the resistance adjustment layer constituting the outermost layer of the conductive roller. In addition, the ten-point average roughness (R _Z ) was measured as the surface roughness.
[0033]
The surface energy was measured as follows. A wetting test solution (made by Wako Pure Chemical Industries, Ltd.) whose surface energy was gradually set to a predetermined value was applied to the roller surface with a cotton swab, and the wettability was confirmed by the presence or absence of repelling.
[0034]
Ten-point average roughness (R _Z ) was measured using a surface roughness meter SJ-301 (manufactured by Mitutoyo Corporation), measurement length: 2.5 mm, measurement speed: 0.6 mm / second, cut-off value: 0.8 mm The measurement conditions were as follows. Further, in order to determine whether or not the drying conditions of the conductive roller are appropriate, the appearance of the conductive roller after the drying process was visually inspected.
[0035]
Example 1
A stainless steel shaft having a diameter of 5 mm and a length of 250 mm was prepared, and epichlorohydrin rubber was coated on the outer periphery of the shaft as a conductive elastic layer, and then finished to a diameter of 7 mm by grinding. The surface roughness (R _Z ) of the conductive elastic layer after this grinding finish was adjusted to be 9.0 to 9.5 μm.
[0036]
A coating solution prepared by mixing 5 parts by weight of a fluorinated olefin resin, 5 parts by weight of an acrylic resin, and 2 parts by weight of carbon black with respect to 90 parts by weight of MEK as a solvent has a thickness of 50 μm on the outer periphery of the epichlorohydrin rubber. The resistance adjustment layer was formed by coating as described above.
[0037]
The roller immediately after the coating liquid was applied was first held for 10 minutes at 50 ° C., which is a temperature lower than the boiling point (79.5 ° C.) of MEK as a solvent, and the first drying was performed. After the MEK vaporization and disappearance is completed by the first drying, the roller is further held for 40 minutes at 130 ° C., which is equal to or higher than the melting point (120 ° C.) of the fluorinated olefin resin. A sex roller was created.
[0038]
(Comparative Example 1)
A conductive roller was produced in the same manner as in Example 1 except that the second drying was performed at 110 ° C., which is a temperature lower than the melting point (120 ° C.) of the fluorinated olefin resin.
[0039]
(Comparative Example 2)
The roller immediately after the coating solution was applied was held at 100 ° C., which is a temperature equal to or higher than the boiling point (79.5 ° C.) of MEK as a solvent, for 40 minutes and dried only once. Otherwise, a conductive roller was prepared in the same manner as in Example 1.
[0040]
Table 1 shows the results of measuring the surface energy and the surface roughness (R _Z ) and the results of visual observation for the conductive rollers of Example 1 and Comparative Examples 1 and 2 manufactured as described above.
[0041]
In Example 1 of the present invention, the surface energy, which is an index of wettability, is as low as 40 dynes / cm, the surface roughness (R _Z ) is as small as 2.47 μm, and the appearance is not problematic because white turbidity is not recognized. It was an evaluation, and a conductive roller having excellent dirt resistance and stable discharge performance could be obtained.
[0042]
The conductive roller of Comparative Example 1 had a problem of contamination resistance because the second drying temperature was a temperature lower than the melting point of the fluorinated olefin, and the surface energy was slightly high at 44 dynes / cm. The conductive roller of Comparative Example 2 had only one drying step, and its temperature was 100 ° C., which exceeds the boiling point of MEK as a solvent. Therefore, the surface energy was as high as 54 dynes / cm, and the surface roughness (R _Z ) Was also as rough as 3.55 μm, and white turbidity was observed on the roller surface, which was not practical.
[0043]
[Table 1]

[0045]
【The invention's effect】
According to the present invention, after applying a coating solution containing at least a fluorinated olefin resin and an acrylic resin, and drying at a temperature below the boiling point of the solvent used in the coating solution, the coating solution is further heated to a temperature equal to or higher than the melting point of the fluorinated olefin resin. Since it dries, the fluorinated olefin melts to reduce the surface roughness of the resistance adjustment layer, and the fluorinated olefin rearranges to reduce the surface energy, thereby forming the outermost layer of the conductive roller. The surface energy and the surface roughness (R _Z ) of the adjustment layer are in a suitable range . In this way, a conductive roller excellent in stain resistance can be manufactured.
According to the invention, the solvent used in the coating solution is methyl ethyl ketone. And it dries at 50 degreeC which is the temperature below the boiling point of the solvent used for a coating liquid, and further dries at the temperature of 120 degreeC or more which is the temperature more than melting | fusing point of fluorinated olefin resin, and forms a resistance adjustment layer. Is preferred. As a result, the surface energy and the surface roughness (R _Z ) of the resistance adjustment layer are surely within a preferable range.
According to the invention, the resistance adjusting layer constituting the outermost layer of the conductive roller includes the fluorinated olefin resin and the acrylic resin. The fluorinated olefin resin reduces the surface energy of the resistance adjustment layer, and the acrylic resin improves the film strength of the resistance adjustment layer and improves the adhesion to the conductive elastic layer. A conductive roller having excellent durability and durability can be obtained. In addition, since the surface energy and the surface roughness (R _Z ) of the resistance adjustment layer forming the outermost layer of the conductive roller are set to be in a suitable range, a conductive roller having further excellent dirt resistance can be obtained. Realized.
[0046]
According to another aspect of the present invention, the conductive roller is provided as a toner charging roller for charging the toner by discharging or charge injection.
[0047]
According to the present invention, since the conductive roller having excellent stain resistance is used as the toner charging roller, the charge amount of the toner charged by the discharge is stabilized, and a stable quality toner image can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a simplified configuration of a conductive roller 1 according to an embodiment of the present invention.
FIG. 2 is a diagram showing a simplified configuration of a developing device 30 according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Conductive roller 2 Shaft body 3 Conductive elastic layer 4 Resistance adjustment layer 30 Developing device

Claims (4)

A shaft body having conductivity, a conductive elastic layer made of an elastic body having conductivity , provided on the outer peripheral surface of the shaft body, and further provided on the outer periphery of the conductive elastic layer , comprising at least a fluorinated olefin resin and an acrylic resin. wherein a surface roughness of ten-point average roughness _{(R Z)} at is at 3.0μm or less, the surface energy is a method for producing a conductive roller and a resistance adjusting layer is not more than 40 dynes / cm,
Preparing the shaft,
Forming the conductive elastic layer on the outer peripheral surface of the shaft body;
Applying a coating liquid in which at least a fluorinated olefin resin and an acrylic resin are dissolved or dispersed in a solvent to the outer periphery of the conductive elastic layer,
Drying at a temperature below the boiling point of the solvent used in the coating solution,
Method for producing a conductive roller, characterized in that thereafter further dried at a temperature above the melting point of the fluorinated olefin resin forming the resistance adjusting layer. The solvent used in the coating solution is methyl ethyl ketone,
Dry at 50 ° C., which is a temperature lower than the boiling point of the solvent used in the coating solution,
2. The method for producing a conductive roller according to claim 1, wherein the resistance adjusting layer is formed by further drying at a temperature of 120 ° C. or higher, which is a temperature higher than a melting point of the fluorinated olefin resin . A conductive roller manufactured by the method for manufacturing a conductive roller according to claim 1 or 2,
An electrically conductive shaft,
A conductive elastic layer provided on the outer peripheral surface of the shaft body and made of a conductive elastic body;
Further provided on the outer periphery of the conductive elastic layer, including at least a fluorinated olefin resin and an acrylic resin, the surface roughness is 10-point average roughness (R _Z And a resistance adjusting layer having a surface energy of 40 dynes / cm or less. Conductive roller 請 Motomeko 3 describes,
A developing device provided as a toner charging roller for charging toner by discharging or charge injection.

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