JP3998192B2 - Charging roller and charging device using the same - Google Patents

Description

【００４３】
得られた各帯電ローラをプリンターに装着して、帯電性能、耐圧性能および耐久性能の夫々につき評価を行った。帯電性能については、正常な画像が出るか否かにつき評価して、正常なものを○、異常なものを×とした。耐圧性能については、異常放電が起きないかどうかにつき評価して、起きないものを○、起こるものを×とした。耐久性能については、初期帯電性能の７０％以上を保持できるか否かにつき評価して、７０％以上保持できるものを○、７０％未満のものを×とした。得られた結果を下記の表２中に各層の抵抗値と併せて示す。
【００４４】
【表２】

【００４５】
【表３】

【００４６】
【発明の効果】
以上説明してきたように、本発明によれば、良好な帯電性能を保持しつつ耐圧性能および耐久性能を向上した、高性能の帯電ローラおよびそれを用いた帯電装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の帯電ローラの一例を示す断面図である。
【図２】帯電装置の一例を示す概略図である。
【図３】実施例で用いた抵抗値測定方法を示す説明図である。
【符号の説明】
１ 帯電ローラ
２ 芯金
３ 基層
４ 接着層
５ 高抵抗層
６ 表面層
７ 電圧印加手段
８ 被帯電体
１０ 各層のシート
１１ 金属円盤
１２ 金属重り
１３ 金属板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charging roller (hereinafter referred to as a charging roller (hereinafter, referred to as a charging roller)) that is suitably used for electrostatic charging of a photosensitive member, a transfer belt or an intermediate transfer belt, or a toner directly in an electrostatic latent image process in a copying machine or a printer In particular, the present invention relates to a cleaning roller and a charging device.
[0002]
[Prior art]
Conventionally, in an electrophotographic apparatus such as a copying machine or a printer, first, the surface of the photoconductor is uniformly charged, and an image is projected from the optical system onto the photoconductor to erase the charged portion of the light. An electrostatic latent image is obtained by an electrostatic latent image process for forming a latent image, and then printing is performed by forming a toner image by attaching toner and transferring the toner image to a recording medium such as paper. Yes.
[0003]
In this case, a corona discharge method has been generally employed as an operation for charging the first photoreceptor. However, this corona discharge method requires application of a high voltage of 6 to 10 kV, which is not preferable from the viewpoint of safety maintenance of the machine, and harmful substances such as ozone and NO _x are generated during corona discharge. There were also environmental problems.
[0004]
For this reason, efforts have been made to charge systems that can be charged at a lower applied voltage than corona discharge and that can suppress the generation of harmful substances such as ozone. There has been proposed a charging method using a contact method in which a charging member to which a voltage is applied is brought into contact with a charged body such as a photosensitive body at a predetermined pressure to charge the charged body.
[0005]
As a charging member used in this contact charging method, for example, a conductive elastic layer (base layer) made of rubber, urethane foam or the like is formed on the outer periphery of a core metal (shaft), and further, surface smoothness is ensured or toner is used. In order to prevent adhesion, a multilayer with a coating layer formed by applying a resin solution in which a resin such as urethane or nylon is dissolved in an organic solvent or a resin solution in which water is dissolved or dispersed in water is applied by dipping or spraying. A charging roller having a structure is known. In addition, in order to improve the adhesion between the base layer and the coating layer, a technique of providing an adhesive layer between these layers is also well known.
[0006]
On the other hand, in order to obtain good charging performance in the charging roller, it is important to adjust the resistance value. Therefore, in the charging roller having such a multilayer film, a different resistance area is set for each layer, and the desired performance is obtained. Techniques to obtain are also known. For example, in the present applicant, in the charging roller in which at least two coating layers are provided on the base layer via the adhesive layer, the resistance value of the base layer and the adhesive layer is set within a predetermined range, respectively. A technique for realizing the performance is proposed (Patent Document 1).
[0007]
[Patent Document 1]
JP 2002-229305 A (Claims etc.)
[0008]
[Problems to be solved by the invention]
By the way, in order to charge the transfer member, the toner and the like, it is necessary to apply a high voltage in order to increase the charging ability. However, the charging roller used so far has insufficient pressure resistance performance with respect to the current requirements, and the durability performance under high voltage is not sufficient, and there is a demand for a charging roller having improved each performance. It was done.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to provide a high-performance charging roller having a multi-layer film structure in which a plurality of layers are laminated on a cored bar and having improved pressure resistance and durability while maintaining good charging performance. It is to provide a charging device using the same.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the charging roller of the present invention is as follows.
(1) A charging roller that contacts a charged body and charges the charged body by applying a voltage between the charged body and a base layer on the outer peripheral surface of the cored bar; In a charging roller in which at least one lower layer and a surface layer are sequentially provided,
The lower layer includes at least one high resistance layer having a resistance value in a range of 10 ¹⁰ to 10 ¹⁶ Ω · cm , the surface layer is a fluororesin, and the resistance value of the high resistance layer is other than It is a charging roller characterized by being at least two orders of magnitude larger than the resistance value of the layer.
[0011]
(2) The charging roller according to (1), further including an adhesive layer between the base layer and the lower layer.
[0013]
(3) The charging roller according to (1) or (2), wherein the high resistance layer has a thickness in the range of 30 to 150 μm.
[0014]
(4) The charging roller according to any one of the above (1) to (3), wherein a JIS 10-point average roughness Rz of a member surface is 6 μm or less.
[0015]
(5) A charging device using the charging roller according to any one of (1) to (4) above.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
As described above, the charging roller of the present invention has a multilayer film structure in which at least one lower layer and a surface layer are formed on a base layer which is a conductive elastic layer, and a predetermined resistance value is formed as one of the lower layers. By providing the high resistance layer having the above, excellent pressure resistance performance and durability performance are realized. FIG. 1 shows a cross-sectional view of a preferred example of the charging roller of the present invention. In the illustrated charging roller 1, a base layer 3 is formed on the outer peripheral surface of a cored bar 2, and a high resistance layer 5 and a surface layer 6 as a lower layer are sequentially provided via an adhesive layer 4.
[0017]
The high resistance layer 5 according to the present invention is 10 ¹⁰ to 10 ¹⁶ Ω · cm, preferably 10 ¹² , which is extremely higher than the resistance range 10 ² to 10 ¹² Ω · cm of a conventional general charging roller film. It is formed to have a resistance value in the range of -10 ¹⁵ Ω · cm. As a result, the pressure resistance performance can be improved and the durability performance under a high voltage can be improved, and a high-performance charging roller satisfying the required roller performance can be realized. In particular, it is preferable to set the resistance value of the high resistance layer 5 to a value that is two orders of magnitude larger than the resistance values of the other layers, whereby the effects of the present invention can be obtained more favorably.
[0018]
As shown in the figure, the high resistance layer 5 is provided as a lower layer on the base layer 3, and if at least one layer is provided, the effect of the present invention can be obtained, but two or more layers may be provided. In the illustrated example, only one lower layer as the high resistance layer 5 is provided, but it is also possible to provide a plurality of lower layers and to form one or more of them as a high resistance layer. In this case, it is necessary that each of the two or more high resistance layers has a resistance value within the above range according to the present invention.
[0019]
In the present invention, the charging roller 1 can satisfy only the point that the high resistance layer 5 is provided between the base layer 3 formed on the cored bar 2 and the surface layer 6 that is the outermost surface layer. In this way, the pressure resistance performance and durability performance improvement effect according to the present invention can be obtained. Other specific roller configurations are not particularly limited, but can be as follows, for example.
[0020]
As the core 2, a conventionally used metal or plastic core can be used as appropriate. Depending on the form of the charging roller or the mechanism of the charging device using the charging roller, the core 2 may be used. It can be omitted.
[0021]
The base layer 3 is composed of an elastic layer imparted with conductivity, and the base material is not particularly limited, and can be formed of rubber or resin, or a foam thereof (hereinafter referred to as “foam”). For example, rubber having a base rubber such as polyurethane, silicone rubber, butadiene rubber, isoprene rubber, chloroprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, epichlorohydrin rubber, etc. A composition. Among these, polyurethane is particularly preferable, and a polyurethane foam having an expansion ratio of 1.5 to 50 times is more preferable. In this case, the foam density is suitably about 0.05 to 0.9 g / cm ³ .
[0022]
The conductive agent added to adjust the resistance value of the base layer 3 is not particularly limited, and lauryltrimethylammonium, stearyltrimethylammonium, octadodecyltrimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, modified fatty acid / dimethylethylammonium. Cation of quaternary ammonium salts such as perchlorate, chlorate, borofluoride, sulfate, ethosulphate, benzyl bromide, benzyl chloride, etc. Surfactant, aliphatic sulfonate, higher alcohol sulfate ester salt, higher alcohol ethylene oxide addition sulfate ester salt, higher alcohol phosphate ester salt, higher alcohol ethylene oxide addition phosphate ester salt, anionic surfactant, etc. Zwitterionic surfactants such as betaine, higher alcohol ethylene oxide, polyethylene glycol fatty acid esters, antistatic agents such as nonionic antistatic agents such as polyhydric alcohol fatty acid _{esters, LiCF 3 SO 3, NaCl 4} , LiAsF 6, LiBF ₄ , metal salts of Group 1 of the periodic table such as Li ⁺ , Na ⁺ and K ⁺ such as NaSCN, KSCN and NaCl, or electrolytes such as NH ₄ ⁺ salts, and Ca ₂ such as Ca (ClO ₄ ) ² A metal salt of Group 2 of the periodic table such as ⁺ and Ba ²⁺ , and these antistatic agents react with an active hydrogen that reacts with at least one or more isocyanates such as a hydroxyl group, a carboxyl group, and a primary or secondary amine group. The thing with the group which has is mentioned. Furthermore, these and the like, complexes of polyhydric alcohols such as 1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol and polyethylene glycol and derivatives thereof, or monools such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether Ionic conductive agents such as complexes with carbon, conductive carbon such as ketjen black EC, acetylene black, carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, MT, etc., color subjected to oxidation treatment (Ink) carbon, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium and other metals and metal oxides, polyaniline polypyrrole, poly Conductive polymers such as acetylene and the like.
[0023]
The resistance value of the base layer 3 is not particularly limited, but can usually be about 10 ² to 10 ¹² Ω · cm, and particularly about 10 ⁴ to 10 ⁵ Ω · cm. As a compounding quantity of the electrically conductive agent for obtaining such resistance value, it is 2.5 to 10 weight%, especially about 3.0 to 5.0 weight%.
[0024]
The adhesive layer 4 is not essential in the present invention, and can be appropriately provided as necessary in order to fulfill the function of improving the adhesion between the base layer 3 and the lower layer. Examples of the forming material include nylon, polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, urethane resin, epoxy resin, urea resin, and the like. By appropriately adding the conductive agent to this, The resistance value can be adjusted similarly to the case of the base layer 2.
[0025]
The resistance value of the adhesive layer 4 is 10 ² to 10 ⁸ Ω · cm, particularly about 10 ⁴ to 10 ⁶ Ω · cm. As the blending amount of the conductive agent for obtaining the resistance value in this range, It is 10 to 80% by weight, particularly about 20 to 60% by weight. The thickness of the adhesive layer 4 is preferably about 1 to 100 μm, and more preferably about 10 to 30 μm, in order to ensure adhesion between the base layer 3 and the lower layer.
[0026]
The lower layer and the surface layer 6 including the high resistance layer 5 can be formed of an appropriate resin as desired. Examples of such a resin include nylon, polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, and epoxy resin. , Urethane resin, urea resin, fluororesin, and the like, but are not limited thereto. In particular, it is preferable that at least one of these layers, particularly the lower layer, contains an acrylic resin. Acrylic resin has a much lower dielectric constant than urethane or nylon, which has been generally used as a charging roller resin, and has a smaller electrostatic capacity. This is because the electric attractive force / repulsive force is reduced, so that the charging noise can be reduced.
[0027]
In this case, the acrylic resin is not particularly limited, but those having a glass transition temperature of −60 to 20 ° C., preferably −50 to 10 ° C. are suitably used. That is, when the glass transition temperature exceeds 20 ° C., it is possible to form a coating film, but cracking or the like is likely to occur immediately during the charging operation, and it may not be practically used, while the glass transition temperature is − Those having a temperature lower than 60 ° C. have good flexibility, but are strongly adhered, and are not so practically preferred due to workability during coating film formation and compatibility with general photoreceptors as charged bodies. In addition, acrylic resins include thermoplastic types and crosslinking types such as self-crosslinking, melamine crosslinking, and isocyanate crosslinking, and any type is suitable as long as it is within the above glass transition temperature range. Can be used. In particular, a thermoplastic type is preferably used in the coating film forming process and from the viewpoint of hardness.
[0028]
Further, the surface layer 6 forming the outermost surface layer of the charging roller 1 is preferably made of a material structure suitable for the purpose of preventing toner adhesion and ensuring surface smoothness, in particular, the surface smoothness of the charging roller and the photoreceptor. From the standpoint of low adhesion to the like, a fluororesin is preferably used. Examples of the fluororesin include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, poly Examples include chlorotrifluoroethylene, chlorotrifluoroethylene-ethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, etc., and those obtained by polymerizing these in a solution or a resin obtained by dissolving a polymerized resin in an organic solvent. Fluorine resin or the like is used.
[0029]
The lower layer and the surface layer 6 including the high resistance layer 5 can be imparted or adjusted with conductivity by adding a conductive agent in the same manner as the base layer 3 and the like. In particular, for the high resistance layer 5, it is possible to add no conductive agent. In the case of adding a conductive agent, the same conductive agent as described above can be used as the conductive agent and is not particularly limited, but is preferably carbon, and in particular, a surface layer that forms the outermost surface layer of the charging roller. 6 is preferably carbon as a conductive agent.
[0030]
The addition amount of the conductive agent can be appropriately adjusted so as to obtain a desired resistance value, but in order to realize the resistance value of the high resistance layer 5, 0 to 20% by weight, particularly 0 to 10%. It is preferable to use about% by weight of a conductive agent. The resistance value of the lower layer and the surface layer 6 other than the high resistance layer 5 is preferably in the range of 10 ³ to 10 ¹² Ω · cm, particularly in the range of 10 ⁵ to 10 ¹⁰ Ω · cm. The addition amount of the conductive agent for obtaining the value is usually about 10 to 100% by weight, particularly about 20 to 50% by weight.
[0031]
Further, in the lower layer and the surface layer, appropriate additives such as thickeners, thixotropy imparting agents, structural viscosity imparting agents and the like can be appropriately added as desired. In this case, the additives are inorganic or organic. Either may be sufficient.
[0032]
The total thickness of the lower layer and the surface layer is not particularly limited, but is preferably a thin layer so as not to impair the flexibility of the base layer 3, and specifically about 50 to 450 μm. In particular, the thickness of the high resistance layer 5 is preferably in the range of 30 to 150 μm in order to appropriately obtain the pressure resistance performance and durability performance improvement effect of the present invention.
[0033]
In addition, although there is no restriction | limiting in particular as a formation method of each layer of the adhesive layer 4, a lower layer, and the surface layer 6, The coating material containing each component which forms these each layer is prepared, and this coating material is apply | coated by the dipping method or the spray method. The method can be preferably used.
[0034]
Further, if the surface of the charging roller is uneven, toner may be clogged in the recess and cause image defects. Therefore, the surface of the member is preferably as smooth as possible, preferably JIS 10-point average roughness. The thickness Rz is 6 μm or less, particularly 3 μm or less, and further 2 μm or less.
[0035]
As described above, the charging roller of the present invention is disposed in contact with a charged body such as a transfer body, and is covered by applying a voltage between the charged body and the charging roller of the present invention. The charged body is charged. In this case, the voltage applied between the charging roller and the member to be charged may be a DC voltage or an AC voltage, and is not particularly limited. However, a voltage obtained by superimposing the AC voltage on the DC voltage is applied. It is preferable to perform charging, whereby the object to be charged can be more uniformly charged. In addition, the contact pressure between the charging roller of the present invention and the member to be charged is preferably 50 to 2000 g, particularly 100 to 1000 g, whereby good charging can be reliably obtained.
[0036]
With respect to the charging device using the charging roller of the present invention, for example, as shown in FIG. A charging device configured to apply a voltage between the body 8 and the body 8 can be exemplified, but is not limited thereto, and the form of the body 8 and the charging roller 1 and the voltage applied by the voltage applying unit 7 are not limited thereto. The application method and the like can be changed as appropriate.
[0037]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to the following Example.
[0038]
Examples 1 to 3, Comparative Examples 1 to 4 and Reference Example First, on the outer periphery of the cored bar 2 as a conductive substrate, in addition to the materials shown below, the amount of carbon black added as a conductive agent (formed By changing the amount of addition relative to 100 parts by weight of polyurethane as shown in Table 1 below, a polyurethane base layer 3 having a resistance value adjusted as shown in Table 2 below was formed at a thickness of 3 mm.
<Material of base layer>
Polyol 100 parts by weight Isocyanate 30 parts by weight
Next, except for Example 3, an adhesive layer 4 having a resistance value adjusted by changing the amount of the conductive agent in the same manner as described above was formed on the base layer 3 with a thickness of 20 μm.
<Material of adhesive layer>
100 parts by weight of polyurethane resin [0040]
Next, the lower layer and the surface layer 6 are formed on the adhesive layer 4 in the same manner as described above, and the resistance values thereof are adjusted, and the film is sequentially formed at the thickness and 5 μm shown in Table 3 below. Produced. Each roller surface obtained had a JIS 10-point average roughness Rz of about 1.0 μm.
<Material of lower layers 1 and 2>
Acrylic resin 100 parts by weight <surface layer material>
Fluororesin 100 parts by weight [0041]
As shown in FIG. 3, the resistance value of each layer is obtained by sandwiching the sheet 10 of each layer between a φ50 metal disk 11 and a metal plate 13 and placing a 500 g metal weight 12 on the metal disk 11. It was obtained by measuring the resistance value when 250 V was applied between the metal disk 11 and the metal plate 13. In this case, a conductive rubber (10 ¹ to 10 ³ Ω · cm) is sandwiched between the sheet 10 and the metal plate 11 and between the sheet 10 and the metal plate 13 to enhance adhesion. Measurement may be performed.
[0042]
[Table 1]

[0043]
Each obtained charging roller was mounted on a printer, and the charging performance, pressure resistance performance and durability performance were evaluated. As for the charging performance, whether or not a normal image appears was evaluated. With regard to the pressure resistance performance, whether or not abnormal discharge occurred was evaluated. With respect to durability performance, whether or not 70% or more of the initial charging performance can be maintained was evaluated. The obtained results are shown in Table 2 below together with the resistance values of the respective layers.
[0044]
[Table 2]

[0045]
[Table 3]

[0046]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a high-performance charging roller and a charging device using the same that have improved pressure resistance and durability while maintaining good charging performance.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a charging roller of the present invention.
FIG. 2 is a schematic diagram illustrating an example of a charging device.
FIG. 3 is an explanatory diagram showing a resistance value measuring method used in an example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Charging roller 2 Core metal 3 Base layer 4 Adhesive layer 5 High resistance layer 6 Surface layer 7 Voltage application means 8 Charged body 10 Sheet of each layer 11 Metal disk 12 Metal weight 13 Metal plate

Claims (4)

A charging roller that contacts a member to be charged and charges the member to be charged by applying a voltage to the member to be charged, comprising a base layer and two layers on the outer peripheral surface of the cored bar In a charging roller in which a lower layer and a surface layer are sequentially provided,
The lower layer comprises a high resistance layer having a resistance value in a range of 10 ¹¹ to 10 ¹³ Ω · cm , and a layer having a resistance value in a range of 10 ⁵ to 10 ¹⁰ Ω · cm, and the high resistance layer thickness in the range of 30~150μm of, and a total thickness of said lower layer and said surface layer is 50～450Myuemu, the surface layer, the resistance value in the range of ¹ 0 5 ^{~10 10 Ω} · cm A charging roller comprising: a fluororesin having a resistance value of the high resistance layer that is two or more orders of magnitude greater than the resistance values of the other layers.   The charging roller according to claim 1, further comprising an adhesive layer between the base layer and the lower layer. The charging roller according to claim 1 or 2 , wherein the member surface has a JIS 10-point average roughness Rz of 6 µm or less. Charging apparatus characterized by using a charging roller as claimed in any one of claims 1-3.

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