JP4570385B2 - Developing roller and image forming apparatus using the same - Google Patents

Developing roller and image forming apparatus using the same Download PDF

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JP4570385B2
JP4570385B2 JP2004112209A JP2004112209A JP4570385B2 JP 4570385 B2 JP4570385 B2 JP 4570385B2 JP 2004112209 A JP2004112209 A JP 2004112209A JP 2004112209 A JP2004112209 A JP 2004112209A JP 4570385 B2 JP4570385 B2 JP 4570385B2
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developing roller
layer
intermediate layer
forming apparatus
image forming
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秀洋 赤間
宏高 田河
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Bridgestone Corp
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Description

本発明は、現像ローラ及び該現像ローラを備えた画像形成装置に関し、特に残留歪の小さい現像ローラに関するものである。   The present invention relates to a developing roller and an image forming apparatus including the developing roller, and more particularly to a developing roller having a small residual distortion.

電子写真複写装置等の画像形成装置には、通常、ウレタン発泡体等からなる弾性層に表層(塗膜層)を配設してなる導電性の現像ローラが使用されている(特許文献1及び2参照)。しかしながら、該現像ローラは、カートリッジに組み込まれて長期間保管された場合、感光ドラムに長期間圧接されることによって、変形が生じ、該変形に起因して画像不良が発生するという問題があった。   In an image forming apparatus such as an electrophotographic copying apparatus, a conductive developing roller in which a surface layer (coating layer) is disposed on an elastic layer made of urethane foam or the like is generally used (Patent Document 1 and Patent Document 1). 2). However, when the developing roller is incorporated in a cartridge and stored for a long time, the developing roller is deformed by being pressed against the photosensitive drum for a long time, and there is a problem that an image defect occurs due to the deformation. .

特に、近年、高速且つ高耐久のカラープリンターにおいて、高品位な画像を得るために、上記現像ローラには、低硬度で且つ残留歪が小さいことが求められている。しかしながら、現像ローラを低硬度化すると、残留歪が大きくなる傾向があり、実際、通常使用されるウレタン発泡体からなる弾性層と表層とからなる現像ローラは、残留歪が大きく、該現像ローラを用いた場合、所望の画像品質を確保できないという問題があった。   Particularly, in recent years, in order to obtain a high-quality image in a high-speed and highly durable color printer, the developing roller is required to have low hardness and small residual strain. However, when the hardness of the developing roller is lowered, the residual strain tends to increase. Actually, the developing roller composed of an elastic layer made of urethane foam and a surface layer, which is usually used, has a large residual strain, and the developing roller is When used, there is a problem that desired image quality cannot be ensured.

特開2002−72628号公報Japanese Patent Laid-Open No. 2002-72628 特開平8−272211号公報JP-A-8-272211

そこで、本発明の目的は、上記従来技術の問題を解決し、残留歪が小さく、画像品質を改善することが可能な現像ローラを提供することにある。また、本発明の他の目的は、かかる現像ローラを備えた高品位な画像を形成することが可能な画像形成装置を提供することにある。   SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a developing roller that solves the above-described problems of the prior art, has a small residual distortion, and can improve image quality. Another object of the present invention is to provide an image forming apparatus capable of forming a high-quality image provided with such a developing roller.

本発明者らは、上記目的を達成するために鋭意検討した結果、ウレタン発泡体からなる弾性層と表層(塗膜層)からなる現像ローラにおいて、弾性層と表層との間に中間層を配設し、該中間層の残留歪の大きさを特定の範囲に規定することで、該現像ローラを組み込んだ画像形成装置の画像品質を改善できることを見出し、本発明を完成させるに至った。   As a result of intensive studies to achieve the above object, the present inventors have arranged an intermediate layer between the elastic layer and the surface layer in the developing roller composed of an elastic layer made of urethane foam and a surface layer (coating layer). And the present inventors have found that the image quality of an image forming apparatus incorporating the developing roller can be improved by regulating the residual strain of the intermediate layer within a specific range, and the present invention has been completed.

即ち、本発明の現像ローラは、ウレタン発泡体からなる弾性層と、該弾性層の外周面上に配置された中間層と、該中間層の外周面上に配置された表層とからなる円柱状の現像ローラにおいて、前記中間層の残留歪が2%以下であり、該中間層が、ポリエーテル鎖を有するウレタン樹脂又は、粒子内架橋構造を有するアクリルエマルジョンを含むものであることを特徴とする。ここで、本発明において、中間層の残留歪とは、該中間層を形成する材料を厚さ500μm、幅2cm、長さ5cmの短冊形状として、該短冊の表面に直径6mmの円柱状の金属棒を当接させ、該金属棒の両端に夫々500gの荷重をかけて室温で一週間放置した後の短冊に残留する凹み量の厚さに対する割合である。 That is, the developing roller of the present invention has a cylindrical shape comprising an elastic layer made of urethane foam, an intermediate layer arranged on the outer peripheral surface of the elastic layer, and a surface layer arranged on the outer peripheral surface of the intermediate layer. in the developing roller, the residual strain of the intermediate layer is Ri der 2%, the intermediate layer, urethane resin having a polyether chain or a feature that is intended to include acrylic emulsion having a particle within the crosslinked structure To do. Here, in the present invention, the residual strain of the intermediate layer refers to a columnar metal having a diameter of 6 mm on the surface of the strip, in which the material forming the intermediate layer is a strip having a thickness of 500 μm, a width of 2 cm, and a length of 5 cm. This is the ratio of the amount of dents remaining in the strip after the bars are brought into contact with each other and a load of 500 g applied to both ends of the metal bars and left at room temperature for a week.

本発明の現像ローラは、ローラのアスカーC硬度が60°以下であるのが好ましい。   The developing roller of the present invention preferably has an Asker C hardness of 60 ° or less.

本発明の現像ローラの好適例においては、前記中間層の厚さが10〜500μmである。   In a preferred embodiment of the developing roller of the present invention, the intermediate layer has a thickness of 10 to 500 μm.

本発明の現像ローラの他の好適例においては、前記表層の体積抵抗値が109Ω・cm以下である。 In another preferred embodiment of the developing roller of the present invention, the surface layer has a volume resistance of 10 9 Ω · cm or less.

本発明の現像ローラの他の好適例においては、前記表層の中心線平均粗さ(Ra)が0.1〜2.0μmである。   In another preferred embodiment of the developing roller of the present invention, the center line average roughness (Ra) of the surface layer is 0.1 to 2.0 μm.

また、本発明の画像形成装置は、上記現像ローラを用いたことを特徴とする。   An image forming apparatus according to the present invention uses the developing roller.

本発明によれば、ウレタン発泡体からなる弾性層と中間層と表層とからなる現像ローラにおいて、中間層の残留歪の大きさを特定の範囲に規定することで、画像品質を改善することが可能な現像ローラを提供するができる。また、該現像ローラを用いた、高品質な画像を形成することが可能な画像形成装置を提供することができる。   According to the present invention, in the developing roller composed of an elastic layer made of urethane foam, an intermediate layer, and a surface layer, the image quality can be improved by defining the size of the residual strain of the intermediate layer within a specific range. A possible developing roller can be provided. In addition, it is possible to provide an image forming apparatus that can form a high-quality image using the developing roller.

以下に、本発明の現像ローラを図1を参照しながら詳細に説明する。図1は、本発明の現像ローラの一例の断面図である。図示例の現像ローラは、シャフト1と、該シャフトの外周面上に形成されウレタン発泡体からなる弾性層2と、該弾性層の外周面上に配置された中間層3と、該中間層の外周面上に配置された表層4とからなり、中間層3の残留歪が2%以下である。本発明の現像ローラにおいては、弾性層2と表層4との間に、残留歪が2%以下の中間層3が配設されているため、現像ローラの残留歪が小さくなり、該現像ローラを組み込んだ画像形成装置の画像品質を改善することができる。なお、シャフト1としては、金属又はプラスチック製のシャフトを用いることができ、現像ローラの形態及び該現像ローラを組み込む画像形成装置の機構によっては、シャフト1を省略することもできる。   Hereinafter, the developing roller of the present invention will be described in detail with reference to FIG. FIG. 1 is a cross-sectional view of an example of the developing roller of the present invention. The developing roller of the illustrated example includes a shaft 1, an elastic layer 2 formed on the outer peripheral surface of the shaft and made of urethane foam, an intermediate layer 3 disposed on the outer peripheral surface of the elastic layer, and the intermediate layer. It consists of the surface layer 4 arrange | positioned on an outer peripheral surface, and the residual strain of the intermediate | middle layer 3 is 2% or less. In the developing roller of the present invention, since the intermediate layer 3 having a residual strain of 2% or less is disposed between the elastic layer 2 and the surface layer 4, the residual strain of the developing roller is reduced. The image quality of the incorporated image forming apparatus can be improved. As the shaft 1, a metal or plastic shaft can be used, and the shaft 1 can be omitted depending on the form of the developing roller and the mechanism of the image forming apparatus incorporating the developing roller.

本発明の現像ローラの弾性層は、ウレタン発泡体からなる。該ウレタン発泡体は、発泡倍率が1.5〜50倍であるのが好ましく、密度が0.05〜0.9g/cm3であるのが好ましく、0.4〜0.5g/cm3であるのが更に好ましい。 The elastic layer of the developing roller of the present invention is made of urethane foam. The urethane foam preferably has an expansion ratio of 1.5 to 50 times, a density of 0.05 to 0.9 g / cm 3 , and more preferably 0.4 to 0.5 g / cm 3 .

上記弾性層には、弾性層の抵抗値を所望の範囲に調整するために、導電剤を添加することができる。該導電剤としては、ラウリルトリメチルアンモニウム、ステアリルトリメチルアンモニウム、オクタドデシルトリメチルアンモニウム、ドデシルトリメチルアンモニウム、ヘキサデシルトリメチルアンモニウム、変性脂肪酸・ジメチルエチルアンモニウム塩の過塩素酸塩、塩素酸塩、ホウフッ化水素酸塩、硫酸塩等の陽イオン性界面活性剤、脂肪族スルホン酸塩、高級アルコール硫酸エステル塩、高級アルコールエチレンオキサイド付加硫酸エステル塩、高級アルコールリン酸エステル塩、高級アルコールエチレンオキサイド付加リン酸エステル塩等の陰イオン界面活性剤、各種ベタイン等の両性イオン界面活性剤、高級アルコールエチレンオキサイド、ポリエチレングリコール脂肪酸エステル、多価アルコール脂肪酸エステル等の非イオン性帯電防止剤、LiCF3SO3、NaCl4、LiAsF6、LiBF4、NaSCN、KSCN、NaCl等の周期律表第1族の金属塩、Ca(ClO42等の周期律表第2族の金属塩等が挙げられる。また、それらと1,4−ブタンジオール、エチレングリコール、ポリエチレングリコール、プロピレングリコール、ポリエチレングリコール等の多価アルコールとの錯体、又はエチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル等のモノオールとの錯体等のイオン導電剤、更には、ケッチェンブラックEC、アセチレンブラック等の導電性カーボン、SAF、ISAF、HAF、FEF、GPF、SRF、FT、MT等のゴム用カーボン、酸化処理を施したカラー(インク)用カーボン、熱分解カーボン、天然グラファイト、人造グラファイト、アンチモンドープの酸化スズ、酸化チタン、酸化亜鉛、ニッケル、銅、銀、ゲルマニウム等の金属及び金属酸化物、ポリアニリンポリピロール、ポリアセチレン等の導電性ポリマー等が挙げられる。これら導電剤の配合量は、特に限定されるものではなく、上記弾性層の体積抵抗率が100〜108Ω・cmの範囲になるように該導電剤を配合するのが好ましく、102〜106Ω・cmの範囲になるように配合するのが更に好ましい。 In order to adjust the resistance value of the elastic layer to a desired range, a conductive agent can be added to the elastic layer. Examples of the conductive agent include lauryltrimethylammonium, stearyltrimethylammonium, octadodecyltrimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, dechlorinated fatty acid / dimethylethylammonium salt perchlorate, chlorate, and borofluoride. , Cationic surfactants such as sulfates, aliphatic sulfonates, higher alcohol sulfate esters, higher alcohol ethylene oxide addition sulfate esters, higher alcohol phosphate ester salts, higher alcohol ethylene oxide addition phosphate ester salts, etc. Nonionic surfactants such as various anionic surfactants, amphoteric surfactants such as various betaines, higher alcohol ethylene oxide, polyethylene glycol fatty acid esters, polyhydric alcohol fatty acid esters, etc. Antistatic agents, LiCF 3 SO 3, NaCl 4 , LiAsF 6, LiBF 4, NaSCN, KSCN, periodic table Group 1 such as NaCl metal salts, Ca (ClO 4) periodic table group 2, such as 2 A metal salt etc. are mentioned. Also, complexes of these with polyhydric alcohols such as 1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol, polyethylene glycol, or complexes with monools such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, etc. In addition, conductive carbon such as ketjen black EC and acetylene black, rubber carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, and an oxidized color (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, polyacetylene, etc. Conductive polymers, and the like. The amount of the conductive agent is not particularly limited, it is preferable to formulate the conductive agent so that the volume resistivity of the elastic layer is in the range of 10 0 ~10 8 Ω · cm, 10 2 More preferably, it is blended in a range of ˜10 6 Ω · cm.

本発明の現像ローラの中間層は、残留歪が2%以下である。本発明において、中間層の残留歪の大きさは、厚さ500μmで2 cm×5 cmの大きさの形状の試験片の表面に直径6 mmの円柱状の金属棒を当接させ、該金属棒の両端に夫々500 gの荷重をかけて室温で一週間放置した後、試験片の当接部の凹み量を測定し、下記式:
式:残留歪=試験片の凹み量/試験片の厚さ×100(%)
から算出される。
The intermediate layer of the developing roller of the present invention has a residual strain of 2% or less. In the present invention, the residual strain of the intermediate layer is measured by bringing a cylindrical metal rod having a diameter of 6 mm into contact with the surface of a test piece having a thickness of 500 μm and a size of 2 cm × 5 cm. After applying a load of 500 g to both ends of the rod and leaving it to stand at room temperature for a week, the amount of dent in the contact part of the test piece was measured, and the following formula:
Formula: Residual strain = dent amount of test piece / thickness of test piece x 100 (%)
Is calculated from

本発明の現像ローラの中間層は、残留歪が2%以下である限り特に限定されるものではないが、該中間層の材料としては、水系樹脂を好適に用いることができる。該水系樹脂としては、水溶性タイプ、エマルジョンタイプ、サスペンジョンタイプ等のいずれのタイプでもよく、また、カルボキシル基、水酸基、アミノ基等の活性水素を有する水系樹脂が好ましい。該水系樹脂としては、ポリエステル系、アクリル系、ウレタン系、ポリジオキソラン等の温水可溶性の樹脂が挙げられ、これらの中でも、アクリル樹脂が好ましい。該アクリル樹脂としては、特に限定されるものではないが、ガラス転移温度が-60〜20℃のものが好ましく、-50〜10℃のものが更に好ましい。また、上記アクリル樹脂には、熱可塑性タイプと、自己架橋、メラミン架橋、イソシアネート架橋等の架橋タイプとがあるが、上記ガラス転移温度の範囲内のものであれば、いずれのタイプのものもでもよく、塗膜形成工程上及び硬度の面から熱可塑性タイプが好ましい。 The intermediate layer of the developing roller of the present invention is not particularly limited as long as the residual strain is 2% or less, but an aqueous resin can be suitably used as the material of the intermediate layer. The aqueous resin may be any type such as a water-soluble type, an emulsion type, and a suspension type, and an aqueous resin having active hydrogen such as a carboxyl group, a hydroxyl group, and an amino group is preferable. Examples of the water-based resin include polyesters, acrylic resins, urethane resins, polydioxolane and other hot water-soluble resins. Among these, acrylic resins are preferable. The acrylic resin is not particularly limited, but preferably has a glass transition temperature of -60 to 20 ° C, more preferably -50 to 10 ° C. In addition, the acrylic resin includes a thermoplastic type and a crosslinking type such as self-crosslinking, melamine crosslinking, and isocyanate crosslinking. The thermoplastic type is preferable from the viewpoint of the coating film forming process and hardness.

上記中間層には、上記弾性層と同様に、導電剤を添加して導電性を調整することができ、中間層の体積抵抗率が103〜1012Ω・cmの範囲になるように導電剤を添加するのが好ましく、105〜1010Ω・cmの範囲になるように添加するのが更に好ましい。中間層に添加する導電剤としては、上記弾性層に添加する導電剤と同様のものを使用することができ、上記導電剤の中でもカーボンが特に好ましい。導電剤の添加量は、導電剤の種類に応じて適宜選択され、例えば、導電剤としてカーボンを用いた場合、0.01〜60質量%添加するのが好ましく、10〜40質量%添加するのが更に好ましい。 As in the elastic layer, a conductive agent can be added to the intermediate layer to adjust the conductivity, and the intermediate layer has a volume resistivity of 10 3 to 10 12 Ω · cm. It is preferable to add an agent, and it is more preferable to add so as to be in the range of 10 5 to 10 10 Ω · cm. As the conductive agent added to the intermediate layer, the same conductive agent as that added to the elastic layer can be used, and carbon is particularly preferable among the conductive agents. The addition amount of the conductive agent is appropriately selected according to the type of the conductive agent. For example, when carbon is used as the conductive agent, 0.01 to 60% by mass is preferably added, and 10 to 40% by mass is further added. preferable.

上記中間層には、必要に応じて増粘剤、チクソトロピー性付与剤、構造粘性付与剤等の添加剤を必要に応じて適量添加することができる。なお、上記中間層の厚さは、特に限定されるものではないが、上述した弾性層の柔軟性を損なわない観点から、10〜500μmの範囲にあるのが好ましい。   If necessary, additives such as a thickener, a thixotropic property-imparting agent, and a structural viscosity-imparting agent can be added to the intermediate layer as necessary. The thickness of the intermediate layer is not particularly limited, but is preferably in the range of 10 to 500 μm from the viewpoint of not impairing the flexibility of the elastic layer described above.

本発明の現像ローラの表層には、特に限定されるものではないが、ナイロン、ポリエステル、ウレタン変性アクリル樹脂、フェノール樹脂、アクリル樹脂、エポキシ樹脂、ウレタン樹脂、尿素樹脂、フッ素樹脂等の樹脂を用いることができ、これらの中でも、現像ローラの表面平滑性や感光ドラムとの低密着性の観点からフッ素樹脂が好ましい。   The surface layer of the developing roller of the present invention is not particularly limited, but a resin such as nylon, polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, epoxy resin, urethane resin, urea resin, or fluorine resin is used. Among these, a fluororesin is preferable from the viewpoint of surface smoothness of the developing roller and low adhesion to the photosensitive drum.

上記フッ素樹脂としては、ポリテトラフルオロエチレン、テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体、テトラフルオロエチレン−ヘキサフルオロプロピレン−パーフルオロアルキルビニルエーテル共重合体、テトラフルオロエチレン−エチレン共重合体、ポリクロロトリフルオロエチレン、クロロトリフルオロエチレン−エチレン共重合体、ポリビニリデンフルオライド、ポリビニルフルオライド等が挙げられる。また、上記表層には、微粒子を水中に分散させたディスパージョンタイプの水系フッ素樹脂を用いるのが好ましく、ポリテトラフルオロエチレンの微粒子を水中に分散させたディスパージョンタイプの水系フッ素樹脂を用いるのが更に好ましい。ここで、フッ素樹脂微粒子の粒径は、5μm以下が好ましく、0.05〜1μmの範囲が更に好ましい。   Examples of the fluororesin include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, polychloroethylene. Examples thereof include trifluoroethylene, chlorotrifluoroethylene-ethylene copolymer, polyvinylidene fluoride, and polyvinyl fluoride. Moreover, it is preferable to use a dispersion type aqueous fluororesin in which fine particles are dispersed in water, and use a dispersion type aqueous fluororesin in which polytetrafluoroethylene fine particles are dispersed in water for the surface layer. Further preferred. Here, the particle diameter of the fluororesin fine particles is preferably 5 μm or less, and more preferably in the range of 0.05 to 1 μm.

上記表層には、上記フッ素樹脂と他の樹脂を混合して用いるのも好ましい。ここで、フッ素樹脂と混合して使用される樹脂としては、ポリビニルアセタール樹脂、ウレタン樹脂、ポリエステル樹脂、アクリル樹脂、ナイロン樹脂、エポキシ樹脂、塩化ビニリデン系共重合体等が挙げられ、1種または2種以上を上記フッ素樹脂と混合して上記表層の形成に用いることができる。これらフッ素樹脂以外の樹脂の中でも、フッ素樹脂の塗膜化及び抵抗均一性の観点から、ポリビニルアセタール樹脂、ウレタン樹脂、ポリエステル樹脂、塩化ビニリデン系共重合体が好ましく、ポリビニルアセタール樹脂が特に好ましい。   It is also preferable to use a mixture of the fluororesin and another resin for the surface layer. Here, examples of the resin used by mixing with the fluororesin include polyvinyl acetal resin, urethane resin, polyester resin, acrylic resin, nylon resin, epoxy resin, vinylidene chloride copolymer, and the like. More than one species can be mixed with the fluororesin and used to form the surface layer. Among these resins other than fluororesins, polyvinyl acetal resins, urethane resins, polyester resins, and vinylidene chloride copolymers are preferable, and polyvinyl acetal resins are particularly preferable from the viewpoints of forming a coating film of fluororesin and uniformity of resistance.

上記表層は、体積抵抗値が109Ω・cm以下であるのが好ましい。該表層には、導電剤を添加して導電性を調整することができ、この場合、導電剤としては、特に限定されるものではないが、上記カーボンが好ましい。該導電剤の添加量は、所望の抵抗が得られるように適宜調整することができ、例えば、導電剤としてカーボンを用いた場合、該カーボンの添加量は、0.01〜40質量%の範囲が好ましく、5〜20質量%の範囲が更に好ましい。 The surface layer preferably has a volume resistance of 10 9 Ω · cm or less. Conductivity can be adjusted by adding a conductive agent to the surface layer. In this case, the conductive agent is not particularly limited, but the carbon is preferable. The addition amount of the conductive agent can be appropriately adjusted so as to obtain a desired resistance. For example, when carbon is used as the conductive agent, the addition amount of the carbon is preferably in the range of 0.01 to 40% by mass. The range of 5 to 20% by mass is more preferable.

上記表層には、必要に応じて増粘剤、チクソトロピー性付与剤、構造粘性付与剤等の添加剤を必要に応じて適量添加することができる。該表層の厚さは、特に制限されるものではないが、30μm以下が好ましく、5〜15μmの範囲が更にこのましい。表層の厚さが30μmを超えると、表層が硬くなって柔軟性が損なわれる場合があり、耐久性が低下して使用によりクラックが発生するおそれがある。   If necessary, an appropriate amount of additives such as a thickener, thixotropy imparting agent, and structural viscosity imparting agent can be added to the surface layer. The thickness of the surface layer is not particularly limited, but is preferably 30 μm or less, and more preferably in the range of 5 to 15 μm. When the thickness of the surface layer exceeds 30 μm, the surface layer may become hard and flexibility may be impaired, and durability may be reduced and cracks may occur due to use.

また、上記表層は、中心線平均粗さ(Ra)が0.1〜2.0μmであるのが好ましい。Raがこの範囲であれば、本発明の現像ローラを画像形成装置に組み込んだ場合、十分に良好な画像を形成することができる。   The surface layer preferably has a center line average roughness (Ra) of 0.1 to 2.0 μm. If Ra is within this range, a sufficiently good image can be formed when the developing roller of the present invention is incorporated in an image forming apparatus.

上記中間層及び表層の形成方法は、特に限定されるものではなく、これら各層を形成する各成分を含む塗料を調製し、該塗料をディッピング法やスプレー法により塗布する方法が好ましく用いられる。   The formation method of the said intermediate | middle layer and surface layer is not specifically limited, The method of preparing the coating material containing each component which forms each of these layers, and apply | coating this coating material by the dipping method or the spray method is used preferably.

本発明の現像ローラは、アスカーC硬度が60°以下であるのが好ましい。アスカーC硬度が60°以下の低硬度なローラであれば、画像形成装置に組み込んだ場合に、十分に良好な画像を形成することができる。   The developing roller of the present invention preferably has an Asker C hardness of 60 ° or less. A low hardness roller having Asker C hardness of 60 ° or less can form a sufficiently good image when incorporated in an image forming apparatus.

本発明の現像ローラの抵抗値は、特に制限されるものではないが、良好な画像を得るために体積抵抗が102〜1012Ω・cmの範囲にあるのが好ましく、105〜1010Ω・cmの範囲にあるのが更に好ましい。 The resistance value of the developing roller of the present invention is not particularly limited, but in order to obtain a good image, the volume resistance is preferably in the range of 10 2 to 10 12 Ω · cm, and 10 5 to 10 10. More preferably, it is in the range of Ω · cm.

本発明の画像形成装置は、上述した現像ローラを用いることを特徴とする。以下に、図2を参照して本発明の画像形成装置を詳細に説明する。図2は、本発明の画像形成装置の一例の部分断面図である。図示例の画像形成装置は、トナー5を供給するためのトナー供給ローラ6と、静電潜像を保持した感光ドラム7と、トナー供給ローラ6と感光ドラム7との間に配置された現像ローラ8と、現像ローラ8に接触するように配置された現像ブレード9と、感光ドラム7に隣接する転写部10と、感光ドラム7に接触するように配置されたクリーニングブレード11とを備える。なお、本発明の画像形成装置は、更に画像形成装置に通常用いられる公知の部品(図示せず)を備えることができる。   The image forming apparatus of the present invention uses the above-described developing roller. The image forming apparatus of the present invention will be described in detail below with reference to FIG. FIG. 2 is a partial cross-sectional view of an example of the image forming apparatus of the present invention. The illustrated image forming apparatus includes a toner supply roller 6 for supplying toner 5, a photosensitive drum 7 holding an electrostatic latent image, and a developing roller disposed between the toner supply roller 6 and the photosensitive drum 7. 8, a developing blade 9 disposed so as to contact the developing roller 8, a transfer unit 10 adjacent to the photosensitive drum 7, and a cleaning blade 11 disposed so as to contact the photosensitive drum 7. The image forming apparatus of the present invention can further include known components (not shown) that are normally used in the image forming apparatus.

トナー供給ローラ6と、現像ローラ8と、感光ドラム7とが、図中の矢印方向に回転することで、トナー供給ローラ6上のトナー5が現像ローラ8を経て感光ドラム7に送られる。トナー5は、現像ローラ8上で現像ブレード9により均一な薄層に整えられ、更に現像ローラ8と感光ドラム7とが接触しながら回転することにより、現像ローラ8から感光ドラム7の静電潜像に付着し、該潜像が可視化する。潜像に付着したトナー5は、転写部10で紙等の記録媒体に転写され、また、転写後に感光ドラム7上に残留するトナー5は、クリーニング部のクリーニングブレード11によって除去される。本発明の画像形成装置においては、現像ローラ8に上述の残留歪の小さい現像ローラを用いるため、高品質な画像を形成することができる。   The toner supply roller 6, the developing roller 8, and the photosensitive drum 7 rotate in the direction of the arrow in the drawing, so that the toner 5 on the toner supply roller 6 is sent to the photosensitive drum 7 through the developing roller 8. The toner 5 is adjusted to a uniform thin layer on the developing roller 8 by the developing blade 9 and further rotated while the developing roller 8 and the photosensitive drum 7 are in contact with each other. It adheres to the image and the latent image becomes visible. The toner 5 attached to the latent image is transferred to a recording medium such as paper by the transfer unit 10, and the toner 5 remaining on the photosensitive drum 7 after the transfer is removed by the cleaning blade 11 of the cleaning unit. In the image forming apparatus of the present invention, since the developing roller having the small residual distortion is used as the developing roller 8, a high-quality image can be formed.

以下に、実施例を挙げて本発明を更に詳しく説明するが、本発明は下記の実施例に何ら限定されるものではない。   Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

導電性のウレタン発泡体(密度0.4〜0.5g/cm3)からなる弾性層の表面に、厚さ50μmの中間層A〜Dを形成し、該中間層の表面に厚さ20μmの表層(Ra=1.0μm)を形成して、各種現像ローラを作製した。また、中間層A〜Dを形成する際に用いた塗料から、厚さ500μmの均一な塗膜フィルムを作製した。なお、中間層Aに用いた塗料は、ポリエーテル鎖を有するウレタン樹脂のディスパージョン100重量部にケッチェンブラック3重量部を分散させた塗料からなり、中間層Bに用いた塗料は、粒子内架橋構造を有するアクリルエマルション100重量部にケッチェンブラック2.5重量部を分散させた塗料からなり、中間層Cに用いた塗料は、アクリルエマルション100重量部にケッチェンブラック2.5重量部を分散させた塗料からなり、中間層Dに用いた塗料は、水溶性アクリル樹脂100重量部にケッチェンブラック2.5重量部を分散させた塗料からなり、表層に用いた塗料は、含フッ素アクリル樹脂100重量部とHDI(ヘキサメチレンジイソシアネート)10重量部とケッチェンブラック3重量部とからなる。 An intermediate layer AD having a thickness of 50 μm is formed on the surface of an elastic layer made of conductive urethane foam (density 0.4 to 0.5 g / cm 3 ), and a surface layer (Ra = 1.0 μm) to form various developing rollers. Moreover, the uniform coating film of thickness 500 micrometers was produced from the coating material used when forming intermediate | middle layer AD. The coating material used for the intermediate layer A is a coating material in which 3 parts by weight of ketjen black is dispersed in 100 parts by weight of a urethane resin dispersion having a polyether chain. It consists of a paint in which 2.5 parts by weight of ketjen black is dispersed in 100 parts by weight of an acrylic emulsion having a crosslinked structure, and the paint used for the intermediate layer C is a paint in which 2.5 parts by weight of ketjen black is dispersed in 100 parts by weight of an acrylic emulsion. The coating material used for the intermediate layer D is a coating material in which 2.5 parts by weight of ketjen black is dispersed in 100 parts by weight of a water-soluble acrylic resin, and the coating material used for the surface layer is 100 parts by weight of a fluorine-containing acrylic resin and HDI. It consists of 10 parts by weight of (hexamethylene diisocyanate) and 3 parts by weight of ketjen black.

作製した現像ローラの両端部に夫々500gの荷重をかけて感光ドラムに当接させて、50℃、95%RHの恒温恒湿槽中で一週間放置した。次に、恒温恒湿槽から取り出した現像ローラをプリンターに装着し、画像を形成させた。当接した部分の線が画像に見られなかった場合を○とし、線が見られた場合を×とし、線が画像に僅かに見られる場合を△とし、○と△の中間の場合を○△とし、線がはっきりと見られた場合を××とした。また、作製した現像ローラのアスカーC硬度を、1kgの荷重の下で測定した。これらの結果を表1に示す。   A load of 500 g was applied to both ends of the produced developing roller so as to contact the photosensitive drum and left for one week in a constant temperature and humidity chamber at 50 ° C. and 95% RH. Next, the developing roller taken out from the constant temperature and humidity chamber was mounted on a printer to form an image. The case where the line of the abutting part is not seen in the image is marked as ◯, the case where the line is seen is marked as x, the case where the line is slightly seen in the image is marked as △, and the case between ◯ and △ is marked as ◯ The case where a line was clearly seen was taken as XX. Further, the Asker C hardness of the produced developing roller was measured under a load of 1 kg. These results are shown in Table 1.

また、作製した塗膜フィルムを2cm×5cmの形状に切り出し、切り出したフィルムの表面に直径6mmの円柱状の金属棒を当接させ、該金属棒の両端に夫々500gの荷重をかけて室温で一週間放置した。その後、塗膜フィルムの当接部の凹み量から、下記式:
式:残留歪=塗膜フィルムの凹み量/塗膜フィルム厚さ×100(%)
を用いて残留歪を算出した。結果を表1に示す。
In addition, the produced coating film was cut into a shape of 2 cm × 5 cm, a cylindrical metal rod having a diameter of 6 mm was brought into contact with the surface of the cut film, and a load of 500 g was applied to both ends of the metal rod at room temperature. Left for a week. Then, from the amount of dent at the contact portion of the coating film, the following formula:
Formula: Residual strain = dent amount of coating film / coating film thickness x 100 (%)
Was used to calculate the residual strain. The results are shown in Table 1.

Figure 0004570385
Figure 0004570385

表1から明らかなように、残留歪が2%以下の中間層を用いた実施例の現像ローラを画像形成装置に組み込むことで、該画像形成装置の画像品質を改善できることが分る。   As is apparent from Table 1, it can be seen that the image quality of the image forming apparatus can be improved by incorporating the developing roller of the embodiment using the intermediate layer having a residual strain of 2% or less into the image forming apparatus.

本発明の現像ローラの一例の断面図である。It is sectional drawing of an example of the developing roller of this invention. 本発明の画像形成装置の一例の部分断面図である。1 is a partial cross-sectional view of an example of an image forming apparatus of the present invention.

符号の説明Explanation of symbols

1 シャフト
2 弾性層
3 中間層
4 表層
5 トナー
6 トナー供給ローラ
7 感光ドラム
8 現像ローラ
9 現像ブレード
10 転写部
11 クリーニングブレード
DESCRIPTION OF SYMBOLS 1 Shaft 2 Elastic layer 3 Intermediate | middle layer 4 Surface layer 5 Toner 6 Toner supply roller 7 Photosensitive drum 8 Developing roller 9 Developing blade 10 Transfer part 11 Cleaning blade

Claims (6)

ウレタン発泡体からなる弾性層と、該弾性層の外周面上に配置された中間層と、該中間層の外周面上に配置された表層とからなる円柱状の現像ローラにおいて、前記中間層の残留歪が2%以下であり、該中間層が、ポリエーテル鎖を有するウレタン樹脂又は、粒子内架橋構造を有するアクリルエマルジョンを含むものであることを特徴とする現像ローラ。 In a cylindrical developing roller comprising an elastic layer made of urethane foam, an intermediate layer arranged on the outer peripheral surface of the elastic layer, and a surface layer arranged on the outer peripheral surface of the intermediate layer, residual strain Ri der 2%, developing roller intermediate layer, urethane resin having a polyether chain or, and characterized in that comprising an acrylic emulsion having intraparticle crosslinking structure. 前記現像ローラは、アスカーC硬度が60°以下であることを特徴とする請求項1に記載の現像ローラ。   The developing roller according to claim 1, wherein the developing roller has an Asker C hardness of 60 ° or less. 前記中間層の厚さが10〜500μmであることを特徴とする請求項1又は2に記載の現像ローラ。   The developing roller according to claim 1, wherein the intermediate layer has a thickness of 10 to 500 μm. 前記表層の体積抵抗値が109Ω・cm以下であることを特徴とする請求項1〜3のいずれかに記載の現像ローラ。 The developing roller according to claim 1, wherein a volume resistance value of the surface layer is 10 9 Ω · cm or less. 前記表層の中心線平均粗さ(Ra)が0.1〜2.0μmであることを特徴とする請求項1〜4のいずれかに記載の現像ローラ。   The developing roller according to claim 1, wherein a center line average roughness (Ra) of the surface layer is 0.1 to 2.0 μm. 請求項1〜のいずれかに記載の現像ローラを用いた画像形成装置。 An image forming apparatus using the developing roller according to any one of claims 1-5.
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