JP2004279731A - Electrifying roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrifying roll which has superior conductivity, contamination resistance, and electrification characteristics and generates a small discharge sound. <P>SOLUTION: The electrifying roll 10 has a 1st conductive elastic layer 12 provided around a mandrel 11 and a 2nd conductive elastic layer 13 provided on the 1st conductive elastic layer 12. The 1st conductive elastic layer 12 is formed of a nitrile rubber foamed body which contains nitrile rubber, conductive carbon black, and a ≥28 wt. pts. plasticizer for 100 wt. pts. nitrile rubber, and has a ≤1.0×10<SP>5</SP>Ω electric resistance when applied with DC -100V and Asker C rubber hardness of ≤40°. The 2nd conductive elastic layer 13 is formed of epichlorohydrin rubber and has a surface-treated layer, whose surface is treated with surface treating liquid containing isocyanate, on the surface. The 1st conductive elastic layer 12 and 2nd conductive elastic layer 13 are joined not via an adhesive. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００７９】
【表２】

【００８０】
【発明の効果】
以上説明したように、本発明によると、導電性、汚染性及び帯電特性に優れ放電音が小さく且つ少ない工程で精度よく製造できる帯電ロールを提供することができる。
【図面の簡単な説明】
【図１】本発明の帯電ロールの概略断面図である。
【図２】本発明の帯電ロールの製造方法の一例を示す断面図である。
【図３】本発明の帯電ロールの製造方法の一例を示す断面図である。
【図４】試験例１の電気抵抗値の測定方法を示す図である。
【符号の説明】
１０ 帯電ロール
１１ 芯金
１２ 第１の導電性弾性層
１３ 第２の導電性弾性層
１２ａ 発泡前の第１の導電性弾性層
２０ クロスヘッドダイス
２１ 芯金ガイド
３０ 金型
３１ 円筒型
３２ コマ
３３ 押さえ金型[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a charging roll used for uniformly charging a photosensitive member of an image forming apparatus such as an electrophotographic copying machine and a printer, or a toner jet copying machine and a printer.
[0002]
[Prior art]
2. Description of the Related Art A charging roll of an image forming apparatus such as an electrophotographic copying machine and a printer is required to have predetermined conductivity in addition to non-contamination of a photoreceptor. Therefore, conventionally, those made of polyurethane or silicone rubber have been used, but various coating layers, surface treatment layers or coating tubes are provided on the surface of various elastic layers for reasons such as contamination of the photoreceptor and charging properties. Have been proposed (see Patent Documents 1 to 4). Conventionally, in order to maintain the charging characteristics of the charging member, high dimensional accuracy of the outer diameter is required.After polishing the elastic layer, it is necessary to provide a coating layer, a surface treatment layer, or a coating tube as described above. Was common.
[0003]
[Patent Document 1]
JP-A-6-175470 (claims, etc.)
[Patent Document 2]
JP-A-5-281831 (claims, etc.)
[Patent Document 3]
JP-A-2002-040760 (claims, etc.)
[Patent Document 4]
JP-A-4-214579 (Claim 2, [0022], etc.)
[Patent Document 5]
JP-A-2002-244457 (Claims, [0018], etc.)
[0004]
[Problems to be solved by the invention]
However, in recent years, charging rolls have been required to have more stable charging characteristics, and there have been demands for reducing discharge noise and reducing costs.
[0005]
Therefore, in order to maintain high charging characteristics at low cost, it is necessary to realize a charging roll that can secure a sufficient nip width with very low hardness even if the dimensional accuracy is somewhat sacrificed. By providing a tube-shaped surface layer on a low-hardness elastic layer, a charging roll satisfying all of these characteristics was realized.
[0006]
Here, the applicant has previously developed a conductive elastic foam layer provided on a support, and a release layer provided on the conductive elastic foam layer. Attention was paid to a transfer member (see Patent Document 5) which is a sleeve member formed in advance with resin. However, with the resin tube disclosed herein, the target hardness cannot be achieved, and when the elastic layer is made to have a low hardness, the resin tube cannot be covered after polishing, so that the resin tube foams in the resin tube. However, it was difficult to realize a foam having low hardness in this tube.
[0007]
In view of such circumstances, an object of the present invention is to provide a charging roll which is excellent in conductivity, contamination, and charging characteristics and has low discharge noise.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have conducted various studies and found that the first conductive elastic layer is a nitrile rubber (NBR) foam, and the second conductive elastic layer is a surface treatment layer of isocyanate. It has been found that the use of an epichlorohydrin rubber (ECO) makes it possible to provide a charging roll which is excellent in conductivity, contamination, and charging characteristics, has a low discharge noise, and can be manufactured accurately in a small number of steps. Reached.
[0009]
A first aspect of the present invention for solving the above-mentioned problems is a first conductive elastic layer provided on a cored bar, and a second conductive elastic layer provided on the first conductive elastic layer. Wherein the first conductive elastic layer contains a nitrile rubber, a conductive carbon black, and a plasticizer in an amount of 28 parts by weight or more based on 100 parts by weight of the nitrile rubber. Electric resistance value when applied is 1.0 × 10 ⁵ Ω or less and a rubber hardness of 40 ° or less in Asker C. The second conductive elastic layer is made of epichlorohydrin rubber and surface-treated with a surface treatment solution containing isocyanate on the surface. The charging roll has a surface-treated layer, and the first conductive elastic layer and the second conductive elastic layer are joined without using an adhesive.
[0010]
A second aspect of the present invention is the charging roll according to the first aspect, wherein the second conductive elastic layer has a rubber hardness of 35 to 75 ° according to JIS A.
[0011]
A third aspect of the present invention is the charging roll according to the first or second aspect, wherein the surface roughness of the second conductive elastic layer is 8 μm or less in Rz.
[0012]
A fourth aspect of the present invention is the charging roll according to any one of the first to third aspects, wherein the thickness of the second conductive elastic layer is 0.3 to 1.2 mm. .
[0013]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the electric resistance value when applying DC-100V is 1.0 × 10 5 ⁴ ~ 1.0 × 10 ⁷ Ω.
[0014]
According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the surface treatment liquid is at least one polymer selected from an acrylic fluoropolymer and an acrylic silicone polymer, and a conductivity-imparting agent. Wherein the charging roll further contains at least one of the following.
[0015]
According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the second conductive elastic layer is a sleeve member formed in advance, and the first conductive elastic layer is formed of the core metal. And a sleeve formed by foaming the first conductive elastic layer before foaming between the sleeve member and the preformed sleeve member.
[0016]
In order to satisfy a predetermined conductivity (electric resistance value), it is necessary to add a sufficient amount of conductive carbon black to the first conductive elastic layer. No nip is obtained. On the other hand, if the added amount of the plasticizer is increased to lower the hardness, the plasticizer migrates to the outer surface of the charging roll and contaminates the contacted photoreceptor. Make it difficult. However, when a nitrile rubber foam, particularly a medium-high nitrile or a high nitrile rubber is used as the first conductive elastic layer, high foaming can be achieved due to low gas permeability of the nitrile rubber, and high conductivity can be obtained. It has been found that a low-contamination and low-hardness foam can be realized. Further, when the second conductive elastic layer is a sleeve member made of preformed epichlorohydrin rubber and the first conductive elastic layer is foamed therein, the second conductive elastic layer can be formed without polishing and without an adhesive. Since the layers can be joined with sufficient strength, an accurate charging roll can be obtained with a small number of steps.
[0017]
FIG. 1 shows a cross section of the charging roll of the present invention. As shown in FIG. 1, the charging roll 10 is provided with a first conductive elastic layer 12 and a second conductive elastic layer 13 on a cored bar 11 in this order. Has a surface treatment layer on the surface.
[0018]
The first conductive elastic layer provided on the core metal of the charging roll of the present invention contains nitrile rubber, conductive carbon black, and 28 parts by weight or more of a plasticizer with respect to 100 parts by weight of the nitrile rubber. And the electrical resistance value when DC-100V is applied is 1.0 × 10 ⁵ It is made of a nitrile rubber foam having an Ω or less and a rubber hardness of 40 ° or less as Asker C. The nitrile rubber is not particularly limited, but is preferably a medium-high nitrile, a high nitrile, or a very high nitrile rubber having a nitrile content of 31% or more from the viewpoint of gas permeability described below. Further, from the viewpoint of easiness of foaming, those having a low Mooney viscosity, for example, having a Mooney viscosity of ML _{1 + 4} It is preferable to use one having a temperature of (100 ° C.) of 45 or less. Although hydrogenated NBR may be used, the hydrogenation rate is preferably 95% or less because peroxide bridging makes it easier to set.
[0019]
The electric resistance of the first conductive elastic layer for satisfying the characteristics as the charging roll is 1.0 × 10 4 ⁵ Ω or less, conductive carbon black is used as a conductivity-imparting agent with an electric resistance of 1.0 × 10 ⁵ Ω or less. For example, 25 parts by weight or more may be added to 100 parts by weight of the nitrile rubber. The type of the conductive carbon black is not particularly limited, and examples thereof include Ketjen Black (manufactured by Lion Corporation) and Toka Black # 5500 (manufactured by Tokai Carbon Corporation).
[0020]
Further, in order to secure a sufficient nip as a charging roll, the first conductive elastic layer needs to have a Asker C rubber hardness of 40 ° or less. Since the nip width can be set to be large when the hardness is low, charging can be preferably performed without unevenness. The rubber hardness of Asker C was measured using a test piece having a thickness of 12 mm or more under a constant load of 1000 gf, and was prepared under the same conditions as the first conductive elastic layer. Here, when the second conductive elastic layer of the manufactured charging roll is peeled off and the first conductive elastic layer is stacked so as to have a thickness of 12 mm or more, almost the same hardness is exhibited.
[0021]
As described above, the electric resistance value is 1.0 × 10 ⁵ When the conductive carbon black is added in an amount of Ω or less, the hardness increases. Therefore, it is necessary to add a plasticizer to lower the hardness. Here, the electric resistance value is 1.0 × 10 ⁵ When carbon black is added in an amount of Ω or less, it is usually necessary to add a plasticizer in an amount of about 70 to 80 parts by weight based on 100 parts by weight of the base rubber. However, the nitrile rubber used in the present invention has a low gas permeability and can have a low hardness when highly foamed. Therefore, the amount of the plasticizer added is, for example, 28 to 40 parts by weight based on 100 parts by weight of the nitrile rubber. It may be low. Since the added amount of the plasticizer is low, the plasticizer does not migrate to the outer surface of the charging roll and does not contaminate the contacted photoconductor. Also, if the added amount of the plasticizer is large, kneading becomes difficult, but in the present invention, the kneading can be suitably performed because the plasticizer content is low. The plasticizer is not particularly limited, and examples thereof include polar oils such as di- (2-hexyl) phthalate (DOP). When DOP is used as a plasticizer, it is difficult to transfer to the second conductive elastic layer made of epichlorohydrin-based rubber, or the charging roll has excellent contamination.
[0022]
The expansion ratio of the nitrile rubber foam is preferably 2.0 to 4.0 times. When the first conductive elastic layer is foamed and molded between the cored bar and the preformed sleeve member, the expansion ratio is determined by the space between the first conductive elastic layer and the sleeve member before foaming. Is determined by the ratio of the amount of the first conductive elastic layer before foaming. Here, when the first conductive elastic layer before foaming is foamed in an unconstrained state, it is necessary to use a material that foams 2.0 to 4.0 times more. By doing so, the two layers can be pressed together and formed, and can be firmly joined. However, excessive foaming is not preferable because the sleeve member bursts. The foaming conditions regulate the foaming ratio under unconstrained conditions depending on the type and amount of the foaming agent, and control with high precision the thickness of the first conductive elastic layer before foaming on the cored bar. , Heating conditions and the like are appropriately set. The foam may be closed cells or open cells. Here, since the nitrile rubber used in the present invention has low gas permeability, the conductive elastic layer having a high expansion ratio as described above can be obtained without adding a gas permeation inhibitor or the like. Therefore, the characteristics of the charging roll do not deteriorate due to the addition of the gas permeation inhibitor and the like. The average cell diameter of the nitrile rubber foam is preferably 100 to 300 μm.
[0023]
The charging roll of the present invention includes a second conductive elastic layer on the first conductive elastic layer. The second conductive elastic layer is made of epichlorohydrin phosphorus-based rubber, and has a surface treatment layer having a surface treated with a surface treatment solution containing isocyanate on the surface.
[0024]
Examples of the epichlorohydrin rubber include epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide copolymer, epichlorohydrin-allyl glycidyl ether copolymer, and epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer.
[0025]
The surface treatment layer is formed by impregnating a surface treatment solution containing isocyanate. As the surface treatment liquid, a solution obtained by dissolving an isocyanate compound in an organic solvent, or a solution obtained by adding carbon black to the solution can be used. At least one selected from an acrylic fluoropolymer and an acrylic silicone polymer can be used. It is preferable to use a surface treatment liquid containing at least one of a kind polymer and a conductivity-imparting agent together with an isocyanate component.
[0026]
Here, as the isocyanate compound, 2,6-tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), paraphenylene diisocyanate (PPDI), 1,5-naphthalene diisocyanate (NDI), and 3,3 -Dimethyldiphenyl-4,4'-diisocyanate (TODI) and the multimers and modified products described above.
[0027]
The acrylic fluorine-based polymer and the acrylic silicone-based polymer are soluble in a predetermined solvent and can react with an isocyanate compound to be chemically bonded. The acrylic fluorine-based polymer is, for example, a solvent-soluble fluorine-based polymer having a hydroxyl group, an alkyl group, or a carboxyl group, and includes, for example, a block copolymer of an acrylic ester and a fluoroalkyl acrylate or a derivative thereof. . The acrylic silicone polymer is a solvent-soluble silicone polymer, and examples thereof include a block copolymer of an acrylate ester and a siloxane acrylate ester and derivatives thereof. These polymers can be used alone or in combination of two or more. The content of the polymer in the surface treatment liquid is preferably 2 to 30% by weight based on the isocyanate component. If the amount is too small, the effect of retaining the carbon black in the surface treatment layer will be small, and if it is too large, the isocyanate component will be relatively small and an effective surface treatment layer cannot be formed.
[0028]
Further, it is preferable to use carbon black as a conductivity imparting agent in the surface treatment liquid. The type of carbon black is not particularly limited, and is the same as described above. The amount of carbon black in the surface treatment liquid is preferably 10 to 40% by weight based on the isocyanate component. If the amount is less than this, effective charging characteristics cannot be exhibited, and if the amount is too large, problems such as falling off occur, which is not preferable.
[0029]
Further, the surface treatment liquid contains a solvent that dissolves the acrylic fluorine-based polymer or acrylic silicone-based polymer and the isocyanate compound. The solvent is not particularly limited, but an organic solvent such as ethyl acetate, methyl ethyl ketone (MEK), and toluene may be used.
[0030]
By providing the surface treatment layer as a surface layer on the charging roll, it is possible to prevent the bleeding of the plasticizer added to the first conductive elastic layer onto the surface of the charging roll. It becomes a charging roll.
[0031]
The rubber hardness of the second conductive elastic layer is preferably 35 to 75 ° according to JIS A, and more preferably 45 to 70 °. If it is lower than the above range, the durability as the charging roll is not satisfied, and if it is higher than the above range, the product hardness becomes high.
[0032]
The surface roughness of the second conductive elastic layer is preferably 8 μm or less, more preferably 6 μm or less, and most preferably 2.5 μm or less. When the surface roughness is 8 μm or less, it is possible to obtain a charging roll to which toner components are not easily attached. However, if it is larger than 8 μm but not larger than 12 μm, it can be used depending on the toner.
[0033]
Preferably, the thickness of the second conductive elastic layer is 0.3 to 1.2 mm. Here, the diameter of the entire charging roll and the diameter of the core metal are not particularly limited, but those usually used are the charging roller having a diameter of about 14 to 18 mm and the core metal having a diameter of about 6 to 8 mm. The preferred range of the thickness is also determined. Also, the length of the charging roll is not particularly limited, but may be, for example, about 210 mm to 320 mm.
[0034]
The charging roller of the present invention has an electrical resistance of 10 when applied with DC-100V in a low-temperature and low-humidity environment (10 ° C, 30% RH) to a high-temperature and high-humidity environment (40 ° C, 80% RH). ⁴ -10 ⁷ Ω.
[0035]
In the charging roll of the present invention, the first conductive elastic layer is made of such a highly foamed and low-hardness nitrile rubber foam, and the second conductive elastic layer is made of epichlorohydrin rubber. Discharge noise can be reduced.
[0036]
The second conductive elastic layer is preferably made of a preformed sleeve member. Assuming that the second conductive elastic layer is a pre-formed sleeve member, the charging roll of the present invention allows the first conductive elastic layer before foaming to foam between the pre-formed sleeve member and the core metal. The first conductive elastic layer becomes a foam having a size regulated by the inner surface of the second conductive elastic layer. Therefore, as a result, the step of polishing the first conductive elastic layer becomes unnecessary. In addition, since the two layers are epichlorohydrin rubber and nitrile rubber, even if the two layers are joined without using an adhesive, they can be bonded with a sufficient strength when using the charging roll.
[0037]
The method for manufacturing the charging roll of the present invention is not particularly limited. For example, a step of forming a sleeve member to be the second conductive elastic layer, a step of providing a surface treatment layer on the outer surface of the sleeve member, Forming a first conductive elastic layer before foaming thereon, and disposing a core metal provided with the first conductive elastic layer before foaming in a sleeve member arranged in a mold and foaming. It can be manufactured by a process. An example of the manufacturing method will be described below.
[0038]
First, a sleeve member to be a second conductive elastic layer is formed by transfer, injection, or extrusion. When molded by transfer or injection molding, if a sleeve member is used with a mirror-polished mold, it will be more accurate and smoother than separately polishing the outer surface, so the outer surface will not be polished for dimensional adjustment You may. This sleeve member is coated on a core metal having the same diameter as the sleeve member, and the surface treatment solution is applied to the surface by immersing the sleeve member in a surface treatment solution, and then heated to form a surface treatment layer on the outer surface of the sleeve member. To form
[0039]
Next, the first conductive elastic layer 12a before foaming is extruded on the core metal 11 using a crosshead die 20 shown in the sectional view of FIG. As shown in FIG. 2, the cored bar 11 is positioned and held by a cored bar guide 21 inside a crosshead die 20 for forming the first conductive elastic layer 12 a before foaming. The core metal 11 is advanced while the unfoamed unvulcanized rubber to be the first conductive elastic layer 12 a before foaming is injected into the crosshead die 20 from an injection hole (not shown), and foamed on the core metal 11. The first conductive elastic layer 12a is extruded. Thereafter, the core metal 11 and the first conductive elastic layer 12a before foaming are cut to a desired length. The first conductive elastic layer 12a before foaming may be formed by injection molding or the like using a mold.
[0040]
Here, FIG. 3 shows a mold for forming the charging roll of the present invention using the core metal 11 coated with the first conductive elastic layer 12a before foaming.
[0041]
The mold 30 includes a cylindrical mold 31 made of a metal pipe member having an inner diameter defined with high precision, and a top 32 holding both ends of the core metal 11. The cylindrical mold 31 and the top 32 are concentric. The holding mold 33 is provided at both ends so as to be in a state. Here, a concave portion 32b is provided around the fitting hole 32a of the core metal 11 of the top 32, and a gas vent hole 32c is provided so as to communicate with the concave portion 32b. Further, both ends of the cylindrical mold 31 and the top 32 are simply brought into contact with each other, and the concave portion 32b communicates with a gap 34 between both ends of the cylindrical mold 31 and the top 32. I have. Therefore, after molding, a space portion remains in the concave portion 32b between the first conductive elastic layer 12 and the top 32, and the space portion communicates with the gas vent hole 32c and the gap 34. ing.
[0042]
In order to foam the first conductive elastic layer 12a before foaming into a charging roll using such a mold 30, first, both ends of the core metal 11 are inserted into the fitting holes 32a of the top 32. On the other hand, the sleeve member 13a is arranged in the cylindrical mold 31, and the top 32 and the cylindrical mold 31 are held by the holding mold 33 (see FIG. 3A). Thereafter, by heating the mold 30, the first conductive elastic layer 12a before foaming is foamed and vulcanized (see FIG. 3 (b)) to obtain a target charging roll 10 (see FIG. 1). ).
[0043]
By such foam molding, the first conductive elastic layer 12 is firmly joined to the metal core 11 and also to the second conductive elastic layer 13. Further, particularly in a high-temperature and high-humidity environment, a problem that rust occurs between the elastic layer of the charging roll and the core metal may sometimes occur, but in the present invention, the rust is reduced by using a nitrile rubber. Occurrence can be reduced. Further, the thickness of the first conductive elastic layer 12a before foaming is defined with high precision, and the dimension after foaming is also defined by the sleeve member 13a held by the cylindrical mold 31 having a highly accurate inner diameter. The foaming conditions are defined with high precision, and the foaming ratio, foaming state, and the like can be controlled with high precision. Of course, such foam molding was realized because a nitrile rubber material was used.
[0044]
Further, since a pipe member having a high-precision inner diameter is used as the cylindrical mold 31, the dimensional accuracy after foam molding can be maintained at a high quality, and the second conductive elastic body 13 having no parting line can be obtained. Can be.
[0045]
Furthermore, since the second conductive elastic layer 13 having the surface treatment layer formed by foam molding is subjected to heat treatment while being pressed against the inner peripheral surface of the cylindrical mold 31, the surface roughness of the surface becomes gentle. Thus, toner filming is more unlikely to occur.
[0046]
In the mold 30 described above, a metal pipe member is used as the cylindrical mold 31. However, instead of this, an elastic sleeve such as a fluorine-based resin or a silicone-based resin is used, and the outer peripheral surface of the elastic sleeve is divided by a mold or the like. You may make it hold | maintain. In this case, the same foam molding can be performed, but there is an effect that the mold can be easily removed from the pipe member.
[0047]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on examples, but the present invention is not limited thereto.
[0048]
(Example 1)
To 100 parts by weight of epichlorohydrin rubber (ECO), 20 parts by weight of Toka black # 4500, 0.5 parts by weight of sodium trifluoracetate, 5 parts by weight of zinc white, 2 parts by weight of stearic acid, and a vulcanizing agent were used as conductive materials. 1.5 parts by weight of each were added and kneaded with a roll mixer. After injection molding, the mixture was subjected to steam vulcanization at 150 ° C. × 1 h to form a rubber sleeve having a thickness of 0.75 mm. Next, 100 parts by weight of ethyl acetate, 20 parts by weight of isocyanate compound (MDI), 4 parts by weight of acetylene black (manufactured by Denki Kagaku), and 2 parts by weight of acrylic silicone polymer (Modiper FS700; manufactured by NOF Corporation) Was subjected to a surface treatment using a surface treatment liquid obtained by dispersing and mixing the resulting mixture in a ball mill for 3 hours to form a surface treatment layer to form a second conductive elastic layer. That is, while keeping the surface treatment liquid at 23 ° C., the rubber sleeve was immersed for 60 seconds, and then heated for 1 hour in an oven maintained at 120 ° C. to form a surface treatment layer.
[0049]
Medium to high nitrile rubber with a nitrile content of 33% (Mooney viscosity: ML _{1 + 4} (100 ° C.) 30) 100 parts by weight, 5 parts by weight of zinc white, 1 part by weight of stearic acid, 25 parts by weight of Toka black # 5500, 30 parts by weight of DOP, 1 part by weight of vulcanizing agent (sulfur), vulcanization aid Rubber mixed with 3.5 parts by weight, 5 parts by weight of a foaming agent ADCA, 3 parts by weight of a foaming aid, and 3 parts by weight of an inorganic foaming agent and kneaded by a roll mixer (first conductive elastic layer before foaming) Is molded to a thickness of 1 mm on a core metal having a diameter of 8 mm, and then coated with a second conductive elastic layer, and heated at 150 ° C. for 1 hour to foam the first conductive elastic layer before foaming. The first conductive elastic layer and the second conductive elastic layer were integrally formed to produce a charging roll of φ14 × 320 mm.
[0050]
(Example 2)
A charging roll was manufactured in the same manner as in Example 1 except that 0.5 parts by weight of sodium trifluoride acetate was used as a conductive material to be added to the rubber sleeve.
[0051]
(Example 3)
A charging roll was manufactured in the same manner as in Example 1 except that 60 parts by weight of Asahi Thermal (manufactured by Asahi Carbon Co., Ltd.) was used as a conductive material to be added to the rubber sleeve.
[0052]
(Example 4)
Medium to high nitrile rubber with a nitrile content of 33% (Mooney viscosity: ML _{1 + 4} (100 ° C.) 30) Instead of 100 parts by weight, a high nitrile rubber having a nitrile amount of 40% (Mooney viscosity: ML _{1 + 4} (100 ° C.) 45) A charging roll was manufactured in the same manner as in Example 1 except that 100 parts by weight was used.
[0053]
(Example 5)
A charging roll was manufactured in the same manner as in Example 1 except that a rubber sleeve was formed by extrusion, the outer surface of the rubber sleeve was polished, and a surface treatment layer was formed to form a second conductive elastic layer.
[0054]
(Comparative Example 1)
To 100 parts by weight of epichlorohydrin rubber, 0.2 parts by weight of sodium trifluoride acetate, 5 parts by weight of zinc white, 2 parts by weight of stearic acid, 1.5 parts by weight of a vulcanizing agent, and 30 parts by weight of calcium carbonate were used as conductive materials. The mixture was kneaded with a roll mixer, and the mixture was press-vulcanized and polished by transfer molding at 160 ° C. for 30 minutes to form a rubber roll having a rubber thickness of 3 mm. Next, while keeping the same surface treatment liquid as in the example at 23 ° C., the rubber roll was dipped for 60 seconds, and then heated for 1 hour in an oven maintained at 120 ° C. to form a surface treatment layer on the rubber roll. A charging roll of φ14 × 320 mm was manufactured.
[0055]
(Comparative Example 2)
The first conductive elastic layer is formed by impregnating a foamed Asker F 30 ° urethane foam with carbon black dispersion to impart conductivity, and is bonded to the second conductive elastic layer with a urethane adhesive. A charging roll was manufactured in the same manner as in Example 1 except that the charging was performed.
[0056]
(Comparative Example 3)
To 100 parts by weight of epichlorohydrin rubber, 20 parts by weight of Toka Black # 5500 as a conductive material, 25 parts by weight of adipate plasticizer di- (2-ethylhexyl) adipate (DOA), 30 parts by weight of calcium carbonate, 5 parts by weight of zinc white, Rubber mixed with 2 parts by weight of stearic acid, 1.5 parts by weight of a vulcanizing agent, 5 parts by weight of a foaming agent ADCA, 3 parts by weight of a foaming aid, and 3 parts by weight of an inorganic foaming agent and kneaded with a roll mixer (before foaming) (A first conductive elastic layer) was formed on a core having a diameter of 8 mm to a thickness of 1.5 mm to produce a charging roll in the same manner as in Example 1.
[0057]
(Comparative Example 4)
A charging roll was manufactured in the same manner as in Comparative Example 3 except that the first conductive elastic layer before foaming was formed on a core having a diameter of 8 mm to a thickness of 1 mm.
[0058]
(Comparative Example 5)
To 100 parts by weight of EPDM, 50 parts by weight of Toka Black # 5500, 75 parts by weight of naphthenic oil, 5 parts by weight of zinc white, 1 part by weight of stearic acid, 2 parts by weight of sulfur, 3.5 parts by weight of a vulcanization aid, ADCA5 Parts by weight, 3 parts by weight of a foaming aid, and 3 parts by weight of an inorganic foaming agent, and kneaded with a roll mixer to form a rubber (first conductive elastic layer before foaming) on a φ8 mm cored bar. A charging roll was manufactured in the same manner as in Example 1 except that the charging roll was formed to a thickness of 1.5 mm.
[0059]
(Comparative Example 6)
A charging roll was manufactured in the same manner as in Comparative Example 5 except that the first conductive elastic layer before foaming was formed on a core having a diameter of 8 mm to a thickness of 1 mm.
[0060]
(Test Example 1)
Regarding the charging rolls of the above Examples and Comparative Examples, the thickness, hardness (Asker C), average cell diameter (average value of 100 cells) and electric resistance of the first conductive elastic layer, and second conductive property Thickness, hardness (JIS A) and surface roughness Rz of the elastic layer, low-temperature and low-humidity environment (L / L: 10 ° C x 20%) and normal temperature and normal humidity environment (N / N: 20 ° C x 50%) of the charging roll -The electric resistance value was measured when each was maintained in a high-temperature and high-humidity environment (H / H: 30 ° C x 85%). In addition, about the 1st electroconductive elastic layer, it peeled off the 2nd electroconductive elastic layer of the manufactured charging roll, and measured. Tables 1 and 2 show the measurement results and the outline of each charging roll.
[0061]
As shown in FIG. 4, the electric resistance value of the charging roll was determined by placing the charging roll 10 on the electrode member 40 made of a SUS304 plate and applying a load of 100 g to both ends of the cored bar 11. The electric resistance value between the gold 11 and the electrode member 40 was measured using ULTRA HIGH RESISTANCE METER R8340A (manufactured by Advantest Corporation). The applied voltage at this time was DC-100V. The resistance value of the first conductive elastic layer was measured in the same manner for the charging roll from which the second conductive elastic layer was peeled off.
[0062]
(Test Example 2): Evaluation of adhesion
In the charging rolls of Examples and Comparative Examples, the first conductive elastic layer and the second conductive elastic layer were peeled off by hand, and the adhesive strength of the two layers was evaluated as follows: ：: sufficiently bonded, Δ: by hand It was evaluated as immediately peeled off, x: not joined. The results are shown in Tables 1 and 2.
[0063]
As a result, although the adhesive strength was good in Examples 1 to 5 and Comparative Example 3, Comparative Example 2 and Comparative Example 5 were not firmly bonded.
[0064]
(Test Example 3): Environmental Characteristics (Image) Evaluation
The charging roll of each of the above Examples and Comparative Examples was attached to a charged portion of a commercially available laser printer (LP-8600FX manufactured by EPSON). The printer was started up and an image was output under each of the L / L, N / N and H / H environments of Test Example 1. 、: No unevenness was observed in the image, Δ: Some unevenness was observed in the image Was evaluated. The results are shown in Tables 1 and 2.
[0065]
As a result, in Examples 1 to 5 and Comparative Examples 1 to 3, good and no unevenness and deterioration were observed in all environments. However, in Comparative Example 5, image unevenness and deterioration were observed in an L / L environment. Was.
[0066]
(Test Example 4): Storage test
The charging rolls of the above Examples and Comparative Examples were assembled to the toner cartridge of a commercially available laser printer (LP-8600FX manufactured by EPSON) and brought into contact with the photoconductor, and the cartridge was kept in an environment of 50 ° C. and 90% RH for 14 days. After that, the cartridge and the charging roll were assembled into a printer to output an image, and the images were compared at this time and the surface of the charging roll was observed with a microscope. , X: Evaluation was made that bleed on the roll surface and deterioration of the image were observed. The results are shown in Tables 1 and 2.
[0067]
As a result, in the charging roll of Comparative Example 3, bleeding was observed on the roll surface, and the image was also deteriorated.
[0068]
(Test Example 5): Pinhole leak test
A commercially available laser printer (LP-8600FX manufactured by EPSON) was attached with a photoconductor having a pinhole of 0.1 mm and the charging rolls of the above Examples and Comparative Examples, and were placed in an environment of 30 ° C. and 85% RH. After holding for days, the images were output and the images at this time were compared. A: no spread of black spots on the pinhole diameter was observed; ：: spread of black spots on the pinhole diameter was slightly observed; Was evaluated. The results are shown in Tables 1 and 2.
[0069]
As a result, in the charging rolls of Examples 1, 2, 4, and 5, no image black spot spread was observed with respect to the pinhole diameter.
[0070]
(Test Example 6): Evaluation of printing toner component adhesion
Attach the charging rolls of the above Examples and Comparative Examples to a commercially available laser printer (LP-8600FX manufactured by EPSON) and observe the roll surface after continuous printing of 5000 sheets with a microscope and compare images. No unevenness was observed in the image without the evaluation. Δ: The roll surface was filmed or unevenness was observed in the image. The results are shown in Tables 1 and 2.
[0071]
As a result, in Examples 1 to 5 and Comparative Examples 2, 3 and 5, there was little filming on the roll surface and no image deterioration was observed. However, in Comparative Example 1, the roll surface was filmed and the image was uneven. Was seen.
[0072]
(Test Example 7): Discharge sound evaluation
The charging roller of each of the above Examples and Comparative Examples was attached to a commercially available laser printer (LP-8600FX manufactured by EPSON) which was replaced with a photoreceptor not incorporating a sponge member or the like as a silencer. The discharge sound was evaluated as ○: comparable, 放電: slightly increased discharge sound, ×: considerably increased discharge sound compared to the discharge sound when the charging roll was used. The results are shown in Tables 1 and 2.
[0073]
As a result, in Example and Comparative Example 3, it was found that the discharge noise was reduced.
[0074]
As shown in Tables 1 and 2, the charging rolls of the examples were charging rolls excellent in all properties such as conductivity, contamination, and charging properties.
[0075]
On the other hand, a comparative example in which the first conductive elastic layer before foaming using ECO or EPDM was molded to the same thickness on a metal core and foamed in the same rubber sleeve as in Example 1. In Comparative Example 4 or Comparative Example 6, foaming was insufficient and a charging roll could not be produced.
[0076]
In Comparative Example 5, which was manufactured by foaming EPDM in the same rubber sleeve as in Example 1, the two layers were not joined with sufficient strength, and the conductive layer was formed in order to obtain a predetermined electric resistance. Since a large amount of carbon was added, the hardness of the first conductive elastic layer was high.
[0077]
Furthermore, in Comparative Example 3, which was manufactured by foaming ECO in the same rubber sleeve as in Example 1, the first conductive elastic layer had a high hardness because the foaming could not be made high as in the example. From the results of the storage test, it was found that the contamination was poor. Therefore, it was found that it is not preferable to increase the amount of the plasticizer added to the charging roll of Comparative Example 3 in order to lower the hardness, because the contamination is further deteriorated.
[0078]
[Table 1]

[0079]
[Table 2]

[0080]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a charging roll that is excellent in conductivity, contamination, and charging characteristics, has low discharge noise, and can be manufactured accurately with few steps.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a charging roll of the present invention.
FIG. 2 is a cross-sectional view illustrating an example of a method for manufacturing a charging roll of the present invention.
FIG. 3 is a cross-sectional view illustrating an example of a method for manufacturing a charging roll of the present invention.
FIG. 4 is a diagram showing a method for measuring an electric resistance value in Test Example 1.
[Explanation of symbols]
10 Charging roll
11 core metal
12 First conductive elastic layer
13 Second conductive elastic layer
12a First conductive elastic layer before foaming
20 crosshead dies
21 Core Guide
30 mold
31 cylindrical type
32 frames
33 Holding mold

Claims (7)

A charging roll comprising: a first conductive elastic layer provided on a cored bar; and a second conductive elastic layer provided on the first conductive elastic layer. The elastic layer contains nitrile rubber, conductive carbon black, and 28 parts by weight or more of a plasticizer with respect to 100 parts by weight of the nitrile rubber, and has an electric resistance of 1.0 × 10 ⁵ Ω when DC-100V is applied. The second conductive elastic layer is made of an epichlorohydrin-based rubber, and is surface-treated with a surface treatment liquid containing isocyanate on the surface, the nitrile-based rubber foam having a hardness of 40 ° or less in Asker C. A charging roll having a surface treatment layer, wherein the first conductive elastic layer and the second conductive elastic layer are joined without using an adhesive. 2. The charging roll according to claim 1, wherein the second conductive elastic layer has a rubber hardness of 35 to 75 ° according to JIS A. 3. 3. The charging roll according to claim 1, wherein the surface roughness of the second conductive elastic layer is 8 μm or less in Rz. The charging roll according to any one of claims 1 to 3, wherein the thickness of the second conductive elastic layer is 0.3 to 1.2 mm. The charging roll according to any one of claims 1 to 4, wherein an electric resistance value when DC-100V is applied is 1.0 × 10 ^{4 to} 1.0 × 10 ⁷ Ω. The surface treatment liquid according to any one of claims 1 to 5, further comprising at least one of a polymer selected from an acrylic fluorine-based polymer and an acrylic silicone-based polymer, and at least one of a conductivity-imparting agent. Charge roll. In any one of claims 1 to 6, wherein the second conductive elastic layer is a preformed sleeve member, and wherein the first conductive elastic layer is formed of the core metal and the preformed sleeve member. A charging roll formed by foaming the first conductive elastic layer before foaming.

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