JP3672656B2 - Semi-conductive roll - Google Patents

Description

【００２０】
（結果に対する評価）
・サンプル１：
膜厚が10μｍのため白抜け防止効果が見られず、伸びが50％未満のため膜の可撓性がなく、表面粗さをコントロールするための充填剤が添加されていないため耐久試験後の印字濃度が低い。
・サンプル２：
膜厚が10〜 100μｍで伸びが50％以上あるため環境試験後の白抜けが防止され、表面粗さをコントロールするための充填剤が添加されたため耐久試験後の印字濃度が改善されている。
・サンプル３：
膜厚が 100μｍを超えているため膜の耐久性と白抜け防止効果は高められたが、これに伴って表面硬度も高くなったためトナー搬送力が低下し印字濃度が低下した。
【００２１】
・サンプル４：
膜厚が10〜 100μｍで伸びが50％以上あるため環境試験後の白抜けが防止され膜の耐久性と白抜け防止効果は認められたが、ロール抵抗が10⁹ Ωを超えているため印字濃度が低下した。
・サンプル５：
膜厚が10〜 100μｍで伸びが50％以上あるため環境試験後の白抜けが防止され膜の耐久性と白抜け防止効果は認められたが、表面粗さをコントロールするための充填剤の粒径が10μｍを超えているためカブリが増加した。
・サンプル６：
膜厚が10〜 100μｍで伸びが50％以上あるため環境試験後の白抜けが防止され膜の耐久性と白抜け防止効果は認められたが、表面粗さをコントロールするための充填剤の粒径が１μｍ未満のため印字濃度が低下した。
【００２２】
【発明の効果】
本発明の半導電性ロールは、最外層に電子伝導性フッ素樹脂からなる半導電性ブリード防止層が設けられているので、シリコーンゴム中の低分子シロキサンおよび／またはシリコーンオイルなどの液状物のブリードが防止され、潜像担持体またはトナーの、固着または移行が発生せず、印字抜け、ムラなどの発生を防止できる。また、そのときの黒ベタの濃度はロール表面の凹凸の状態、摩擦係数、電気抵抗値に依存するため、初期印字の濃度が十分に確保され、耐久試験後も十分な濃度を得ることができる。更に、弾性半導電体層が電子伝導性シリコーンゴム、また半導電性ブリード防止層が電子伝導性フッ素樹脂であるため、空気中の水分による加水分解がなく、潜像担持体への固着やトナーの固着がない。
このような特性に加えて、上記電子伝導性シリコーンゴムおよび電子伝導性フッ素樹脂の電子伝導性付与剤が導電性カーボンブラックまたは導電性金属酸化物であるときは、温度、湿度に対する電気抵抗の依存性が殆どなく、常に安定した印字特性を得ることができる。
【図面の簡単な説明】
【図１】（ａ）、（ｂ）はそれぞれ本発明の半導電性ロールの異なる態様を例示する断面説明図である。
【図２】実施例で使用した電子写真式プリンターの断面説明図である。
【符号の説明】
１…導電性軸体、２ａ…ソリッド状の弾性半導体層、
２ｂ…スポンジ状の弾性半導体層、３…半導電性ブリード防止層、
10…感光ドラム、11…帯電ロール、12…現像ロール、13…トナー搬送ロール、
14…転写ロール、15…クリーニングロール、16…攪拌機、
17…摩擦帯電ブレード、18…ＬＥＤアレイ、19…容体、20…記録紙。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductive roll useful as a paper feed roll, a developing roll, a charging roll, a transport roll, a transfer roll, a platen roll, and the like used in a copying machine, an LBP (laser beam printer), and a facsimile machine.
[0002]
[Prior art]
As an example of the use of a semiconductive roll comprising a conductive shaft and an elastic semiconductive layer provided on the outer peripheral surface, a latent image is obtained by carrying a frictionally charged toner on the outer peripheral surface in a thin layer state. As a developing device for visualizing an electrostatic latent image formed on a carrier, there is an electrophotographic printer as shown in FIG.
In the figure, 10 is a photosensitive drum, 11 is a charging roll, 12 is a developing roll, 13 is a toner transport roll, 14 is a transfer roll, 15 is a cleaning roll, 16 is a stirrer, 17 is a friction charging blade, and 18 is an LED array. , 19 is a container, and 20 is a recording paper.
Semiconductive rolls for such applications are required to have various properties such as conductivity, environmental resistance, low hardness, and tribo-charging properties, and impart conductivity to materials such as urethane rubber, NBR, and silicone rubber. It has been produced by adding and blending an ionic conductive additive and an electronic conductive filler as an agent.
[0003]
[Problems to be solved by the invention]
In the semiconductive roll made of an elastic material such as urethane rubber and NBR, since the hardness is reduced by adding various process oils and softeners to the elastic material, urethane or nylon is applied to the surface of the semiconductive roll. Protective layers of various resins such as ^R were provided to prevent the occurrence of bleeding. For example, when left for a long time under high temperature and high humidity, the resin component is hydrolyzed and the latent image carrier These environmental resistance characteristics, such as sticking to the surface, are not always satisfactory. In particular, when an ion conductive additive is used, changes in electrical resistance characteristics at high temperature / high humidity or low temperature / low humidity, that is, the electrical resistance value is largely dependent on the environment, and development characteristics may be significantly impaired. .
When silicone rubber is used as the elastic material, the environmental resistance is very stable and the electrical resistance is not dependent on the environment. However, the surface of the latent image carrier is made of unreacted low-molecular siloxane and / or silicone oil. Occasionally, it was contaminated to impair development characteristics.
Accordingly, an object of the present invention is to provide a semiconductive roll which has no contamination of the latent image carrier and no environmental dependency of the electric resistance value, and has both stable triboelectric charging characteristics and development characteristics.
[0004]
[Means for Solving the Problems]
The present invention has been completed as a result of intensive studies focusing on the environmental resistance of silicone rubber and fluororesin and the barrier property against low molecular weight siloxane of fluororesin, and the semiconductive roll of the present invention has a conductive shaft body. An elastic semiconductor layer made of electron conductive silicone rubber and a semiconductive bleed prevention layer made of electron conductive fluororesin are sequentially laminated on the outer peripheral surface.
This semiconductive roll also has a thickness in which the semiconductive bleed prevention layer is composed of a fluororesin and an electron conductive filler having an average particle diameter of 1 to 10 μm, particularly conductive carbon black or conductive metal oxide. It is preferable that the volume resistivity is 10 ¹ to 10 ⁹ Ω · cm with a length of 10 to 100 μm and an elongation of 50% or more.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Next, details of the present invention will be described with reference to FIGS.
FIG. 1A relates to a first embodiment of a semiconductive roll, wherein 1 is a conductive shaft body, 2a is an electron conductive silicone rubber formed on the outer peripheral surface of the conductive shaft body 1. The solid elastic semiconductor layer 3 is a semiconductive bleed prevention layer made of an electron conductive fluororesin formed on the elastic semiconductor layer 2a.
FIG. 1B relates to a second embodiment of the semiconductive roll. In the semiconductive roll of FIG. 1A, a sponge-like elastic semiconductor layer 2b is used instead of the solid elastic semiconductor layer 2a. Other than that, it is the same material and composition.
[0006]
In the semiconductive roll, the conductive shaft 1 has an insulating property made of a thermoplastic resin and / or a thermosetting resin in addition to a so-called “core” made of iron, aluminum, SUS, brass, or the like. Core body formed by electroplating the surface of the core body, formed of a conductive resin molded product in which a thermoplastic resin and / or a thermosetting resin is mixed with carbon black as a conductivity imparting agent, metal powder, etc. As long as it is electrically conductive, such as a core made of a combination of these materials, a material made of any material selected from plastics, metals, and ceramics is used.
One end of the conductive shaft 1 is grounded or a bias voltage is applied, thereby electrostatically charging the electrostatic latent image carrier, injecting charges into the toner, and transporting the toner to the electrostatic latent image carrier. It performs functions such as developing electrostatic latent images.
[0007]
The electron conductive silicone rubber used for forming the elastic semiconductor layer 2 is any one or more of dimethyl silicone raw rubber, methyl vinyl silicone raw rubber, methylphenyl silicone raw rubber, fumed silica, precipitated silica, conductive carbon black. After mixing one or more of metal powder, metal oxide, etc. in a desired ratio, kneading them together, adding a vulcanizing agent such as peroxide and platinum catalyst, and further a blowing agent as required. It can be obtained as a solid (2a) or sponge (2b) as shown in the figure by heat curing and crosslinking.
As a specific example, 6 to 30 parts by weight of carbon black and 10 to 35 parts by weight of fumed silica-based filler are added to 100 parts by weight of organic peroxide-reactive silicone raw rubber and kneaded with a pressure kneader. Examples thereof include a method of adding 2.0 parts by weight of an organic peroxide vulcanizing agent.
[0008]
The elastic semiconductor layer 2 generally has a volume resistivity of 10 ¹ to 10 ⁹ Ω · cm. If this is out of the above range, fogging, a decrease in transfer efficiency, and inconsistency in print density are likely to occur.
The elastic semiconductor layer 2 acts as an electrode for charging and developing process, a contact charging to toner and an electrode for charge injection. In the toner conveying process and developing process, the surface irregularities and van der Waals force, mirror image force It is carried and conveyed on the roll surface by Coulomb force or the like. The elastic semiconductor layer 2 is excellent in environmental resistance to temperature and humidity, and uses an electron conductive conductivity imparting agent, so that the electrical resistance value has very little environmental dependency.
[0009]
The electron conductive fluororesin used for the formation of the semiconductive bleed prevention layer 3 is composed of a fluoroethylene vinyl ether copolymer as a basic structure, and an inorganic or organic electron conduction having an average particle size of 1 to 10 μm as a conductivity imparting agent. An isocyanate-based cross-linking agent, for example, conductive carbon black, conductive zinc oxide, metal oxides such as conductive tin oxide and antimony oxide, and the like made semiconductive by adding various metal powders It can be obtained by crosslinking with
In the fluoroethylene vinyl ether copolymer, the elongation and friction coefficient of the semiconductive bleed preventing layer 3 can be arbitrarily adjusted by changing the type of functional group of the side chain of the vinyl ether unit, for example, an alkyl group or an alkylene group. Can do. In particular, when the elongation is adjusted, the flexibility of the surface layer can be improved, whereby a roll having excellent flexibility can be obtained. At that time, if the elongation is less than 50%, the bleed prevention layer may crack during use and the bleed prevention effect may be lost. Therefore, the elongation is preferably adjusted to 50% or more.
[0010]
The use of particles having an average particle diameter of 1 to 10 μm in the electron conductive filler is advantageous because it can arbitrarily change the conveying force for the toner and at the same time can suppress a decrease in the toner conveying force due to wear and the like over time. is there. When the average particle size of the filler is less than 1 μm, the surface roughness cannot be ensured by simply adding and blending and molding, and the toner conveying force becomes inferior. It is necessary to use a mold having a surfaced cavity, or to carry out post-processing (ensuring surface roughness by sandblasting or the like) after molding. On the other hand, when the average particle diameter exceeds 10 μm, the toner conveying force is too large and the image is deteriorated.
[0011]
The semiconductive bleed prevention layer 3 made of this electron conductive fluororesin is generally used having a volume resistivity of 10 ¹ to 10 ⁹ Ω · cm, preferably 10 ³ to 10 ⁷ Ω · cm. If this is outside the range of 10 ¹ to 10 ⁹ Ω · cm, fogging, transfer efficiency decline, and print density mismatch are likely to occur.
If the film thickness of the semiconductive bleed prevention layer 3 is 10 μm or more, the effect of preventing bleed is sufficiently obtained, and if it is 100 μm or less, the flexibility as a roll is sufficient and the printing characteristics are not deteriorated. This film thickness is preferably 10 to 100 μm.
The semiconductive bleed prevention layer 3 prevents the low molecular siloxane and / or silicone oil in the semiconductive silicone rubber layer described above from bleeding. As a result, adhesion and / or migration of low molecular siloxane and / or silicone oil to the electrostatic latent image carrier and toner can be prevented, and a printed matter free from print omission, unevenness and fog can be stably obtained.
Furthermore, the semiconductive bleed prevention layer 3 is excellent in environmental resistance to temperature and humidity, and uses an electron conductive conductivity imparting agent, so that the electrical resistance has very little environmental dependency.
[0012]
The semiconductive roll of the present invention is a method in which the conductive shaft body and the electron conductive silicone rubber are integrally separated by 1) using a crosshead in an extruder and then primary vulcanized in a gear oven or an IR furnace. 2) A method in which the conductive shaft body is set in a mold, and then the silicone rubber composition is injected, and primary vulcanization is performed at room temperature or under heating, or 3) the conductive shaft body and the silicone rubber composition are simultaneously molded into the mold. It is formed into a roll by an arbitrary processing method such as heating and compression molding in a mold. Thereafter, the physical properties can be stabilized by secondary vulcanization for a certain period of time in a gear oven or the like.
The obtained roll-shaped molded product is used as it is or, if necessary, after making it into a desired surface state with a cylindrical grinder, shot blaster, sand blaster, lapping machine, buff, etc., and then on the surface of this roll-shaped molded product. After applying the electron conductive fluororesin by dipping, spray coating, roll coating, etc., it is cured by a method such as room temperature curing, heat curing, ultraviolet curing, electron beam curing, etc. It can be a roll.
[0013]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to description of these Examples.
(Example 1)
As a conductive shaft, use a shaft of electroless nickel plated SUM22 with a diameter of 10 mm and a length of 250 mm, and apply silicone primer: Primer No. 16 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) to this outer peripheral surface. Baking was performed in a gear oven at 150 ° C. for 10 minutes.
As an electron conductive silicone rubber, organic peroxide reaction type silicone raw rubber: KE-78VBS (same as above) 100 parts by weight, carbon black: thermal black (Asahi Carbon Co., Ltd., trade name) 10 parts by weight and fumed silica -Based filler: Aerosil 200 (Nippon Aerosil Co., Ltd., trade name) 25 parts by weight was added and kneaded in a pressure kneader, then organic peroxide vulcanizing agent: C-8 (manufactured by Shin-Etsu Chemical Co., Ltd., Product name) Prepared with 2.0 parts by weight added, inserted into a compression mold consisting of a cylindrical cavity with an inner diameter of 20 mm, and vulcanized and bonded to the conductive shaft at 175 ° C for 10 minutes . Thereafter, secondary vulcanization was carried out at 200 ° C. for 7 hours in a gear oven, and polishing was performed with a cylindrical grinder to obtain a roll-shaped molded product having a diameter of 18 mm and a length of 210 mm.
Next, 100 parts by weight of fluororesin-based paint containing an isocyanate-based crosslinking agent: Lumiflon (trade name, manufactured by Asahi Glass Co., Ltd.) was coated with tin oxide (antimony oxide dope) on the surface of titanium oxide powder having an average particle size of 0.2 μm. Electronic conductive filler: W-1 (Mitsubishi Materials Corporation, trade name) 50 parts by weight was applied to the surface of the roll-shaped molded product with a spray coating machine with a coating thickness of 30μm, and gear The semiconductive roll of the present invention was obtained by baking and curing in an oven at 150 ° C. for 30 minutes.
[0014]
On the other hand, the electrophotographic printer shown in FIG. 2 is used as a developing device for visualizing the electrostatic latent image formed on the latent image carrier by the frictionally charged toner carried in a thin layer state on the outer periphery of the developing roll. A continuous printing test was conducted using the semiconductive roll as the developing roll. As a result, fog and print density were good even after printing 6,000 sheets. At the same time, the surface of the developing roll was observed with a microscope, but no toner was fixed.
Further, the unused developing rolls were brought into contact with both ends of the latent image carrier with a force of 2 kgf (total 4 kgf), respectively, and left in an environment tester in an environment of 50 ° C. and 80% RH for 120 hours. When the presence or absence of fixation to the latent image carrier was confirmed, no fixation was observed and the latent image carrier was not altered. Thereafter, the latent image carrier was mounted on the electrophotographic printer, and a halftone dot and black solid print test was performed. As a result, a good print state without print omission was obtained.
[0015]
(Example 2 and comparative example)
In the same manner, Samples 1 to 6 in which the elongation of the semiconductive bleed prevention layer, the particle size of the filler, the resistance value, the film thickness and the like were changed as shown in Table 1 were produced. Moreover, the following test items were measured together with Example 2 using the roll-shaped molded product as it was as a developing roll, and the results are shown in Table 1.
[0016]
(Test items)
・ Roll resistance:
The rubber roll before coating was placed on a gold-plated electrode 5 mm longer than the entire length of the rubber, a weight of 500 g was applied to both ends of the rubber roll, a voltage of 10 V was applied between the shaft of the rubber roll and the surface, and the resistance value was measured.
・ Membrane resistance:
After the fluororesin semiconductive coating agent was cured on the polyester sheet, the volume resistivity was measured by a method according to SRIS2301.
・ Film thickness:
The coating cross section of the semiconductive roll was measured using a tool microscope.
・ Elongation of membrane:
A tensile test was performed on a sheet of semiconductive fluororesin cured at a thickness of 0.5 mm on a tetrafluoroethylene plate according to JIS K 6301, and the elongation was measured.
[0017]
・ White spots:
After the semiconductive roll contacted and left on the photosensitive drum, the photosensitive drum was incorporated into an electrophotographic printer to perform halftone dot printing, and the presence or absence of printing abnormality at the contact portion was visually confirmed.
Judgment was made based on the presence or absence of a print density lowering portion in halftone dot printing by an environmental test machine, and any so-called white spots were rejected.
・ Fog:
The semiconductive roll was incorporated into an electrophotographic printer, and black solid, halftone dot, 5% duty, white background printing, etc. were repeated, and the Macbeth density of the white background portion of the 5% duty image was measured using a Macbeth densitometer. Both initial and post-end fog values exceeding 0.015 were rejected.
・ Print density:
The Macbeth density of the black solid print portion printed by the same method as that for fogging was measured using a Macbeth densitometer. The initial and post-endurance concentrations below 1.3 were rejected.
[0018]
-Toner adhesion:
The roll surface after the endurance test was observed with a microscope, and the sticking was observed as rejected.
・ Latent image carrier fixing:
Those in which sticking was observed on the roll surface and the photosensitive drum surface after the environmental test were rejected.
・ Membrane breakage:
The film after the durability test was observed with a microscope, the presence or absence of a damaged part was confirmed, and the damaged part was rejected.
[0019]
[Table 1]

[0020]
(Evaluation of results)
Sample 1:
Since the film thickness is 10μm, no white spot prevention effect is seen, the elongation is less than 50%, the film is not flexible, and no filler is added to control the surface roughness. Print density is low.
Sample 2:
Since the film thickness is 10 to 100 μm and the elongation is 50% or more, white spots after the environmental test are prevented, and the filler for controlling the surface roughness is added, so that the print density after the durability test is improved.
Sample 3:
Since the film thickness exceeded 100 μm, the durability of the film and the effect of preventing white spots were enhanced. However, the surface hardness was increased accordingly, so that the toner conveying force was lowered and the printing density was lowered.
[0021]
Sample 4:
Since the film thickness is 10-100 μm and the elongation is 50% or more, white spots after the environmental test are prevented and the durability of the film and the effect of preventing white spots are recognized. However, since the roll resistance exceeds 10 ⁹ Ω, printing is performed. The concentration decreased.
Sample 5:
Since the film thickness is 10-100μm and the elongation is 50% or more, white spots are prevented after the environmental test, and the durability of the film and the effect of preventing white spots are recognized. However, the filler particles are used to control the surface roughness. The fog increased because the diameter exceeded 10 μm.
Sample 6:
Since the film thickness is 10-100μm and the elongation is 50% or more, white spots are prevented after the environmental test, and the durability of the film and the effect of preventing white spots are recognized. However, the filler particles are used to control the surface roughness. Since the diameter was less than 1 μm, the printing density was lowered.
[0022]
【The invention's effect】
Since the semiconductive roll of the present invention is provided with a semiconductive bleed prevention layer made of an electron conductive fluororesin in the outermost layer, the bleed of a liquid material such as low molecular siloxane and / or silicone oil in silicone rubber is provided. Is prevented, and the latent image carrier or toner is not fixed or transferred, and the occurrence of printing omission and unevenness can be prevented. Further, since the density of the black solid at that time depends on the state of unevenness on the roll surface, the friction coefficient, and the electric resistance value, the density of the initial printing is sufficiently secured, and a sufficient density can be obtained even after the durability test. . Further, since the elastic semiconductive layer is an electron conductive silicone rubber and the semiconductive bleed prevention layer is an electron conductive fluororesin, it is not hydrolyzed by moisture in the air, and is fixed to the latent image carrier or toner. There is no sticking.
In addition to these characteristics, when the electron conductivity imparting agent for the electron conductive silicone rubber and the electron conductive fluororesin is conductive carbon black or conductive metal oxide, the electrical resistance depends on temperature and humidity. There is almost no property, and stable printing characteristics can always be obtained.
[Brief description of the drawings]
FIGS. 1A and 1B are cross-sectional explanatory views illustrating different aspects of a semiconductive roll of the present invention.
FIG. 2 is an explanatory sectional view of an electrophotographic printer used in Examples.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Conductive shaft, 2a ... Solid elastic semiconductor layer,
2b ... a sponge-like elastic semiconductor layer, 3 ... a semiconductive bleed prevention layer,
10 ... photosensitive drum, 11 ... charging roll, 12 ... developing roll, 13 ... toner transport roll,
14 ... transfer roll, 15 ... cleaning roll, 16 ... stirrer,
17 ... friction charging blade, 18 ... LED array, 19 ... container, 20 ... recording paper.

Claims (2)

A semiconductive material comprising an elastic semiconductor layer made of an electron conductive silicone rubber and a semiconductive bleed prevention layer made of an electron conductive fluororesin, which are sequentially laminated on the outer peripheral surface of the conductive shaft body. Sex roll. The semiconductive bleed prevention layer is made of a fluororesin and an electron conductive filler having an average particle diameter of 1 to 10 μm, has a thickness of 10 to 100 μm, an elongation of 50% or more, and a volume resistivity of 10 ¹ to 10 ^The semiconductive roll according to claim 1, which is ⁹ Ω · cm 2.

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