JPH09226973A - Semiconductive roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a semiconductive roll to be equipped with both of stable friction electrification and development characteristics by laminating an elastic semiconductor layer composed of an electronic conductive silicone rubber and a semi-conductive bleeding prevention layer formed from an electronic conductive fluororesin in sequence on an outer periphery surface of a conductive shaft body. SOLUTION: A first roll consists of a conductive shaft body 1, a solid elastic semiconductor layer 2a made of an electronic conductive silicone rubber formed on an outer periphery surface of the conductive shaft body 1, and a half conductive bleeding prevention layer 3 made of an electronic conductive fluorine resin formed on the elastic conductor layer 2a (a). A second roll comprises the conductive shaft body 1, a spongiose elastic conductor layer 2b made of the electronic conductive silicone rubber formed on the outer periphery surface of the conductive shaft body 1, and the semi-conductive bleeding prevention layer 3 made of the electronic conductive fluororesin formed on the elastic conductor layer 2b (b). In this case, the volume resistivity values of the elastic semiconductor layers 2a, 2b are made in the range of 10<1> -10<9> Ω.cm, and the half conductive bleeding prevention layer 3 utilizes an electronic conductive filler with average grain diameter of 1-10μm.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a copier, an LBP
The present invention relates to a semiconductive roll which is 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 (laser beam printer), facsimile, and the like.

[0002]

2. Description of the Related Art As an example of the use of a semiconductive roll composed of a conductive shaft and an elastic semiconductive layer provided on the outer peripheral surface thereof, triboelectrically charged toner is carried on the outer peripheral surface in a thin layer state. As a developing device for visualizing the electrostatic latent image formed on the latent image 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 conveying roll,
14 is a transfer roll, 15 is a cleaning roll, 16 is a stirrer, 17 is a friction charging blade, 18 is an LED array, 19 is a container, and 20 is recording paper. The semiconductive roll for such applications is required to have various characteristics such as conductivity, environment resistance, low hardness, and triboelectrification property. Urethane rubber, NB
It has been produced by adding and blending an ion conductive additive and a conductive filler as a conductivity imparting agent to materials such as R and silicone rubber.

[0003]

The urethane rubber, N
In semi-conductive roll made of an elastic material such as BR, because it was lowered hardness by adding a liquid, such as various process oils and softeners elastic material, beginning with a urethane or nylon ^R on the surface of the semiconductive roller Although a protective layer of various resins was provided to prevent bleeding, for example, when left at high temperature and high humidity for a long time, the resin component hydrolyzes and sticks to the latent image carrier. However, these environmental resistance characteristics are not always satisfactory. In particular, when the ion conductive additive was used, the change in the electric resistance characteristics at high temperature / high humidity or low temperature / low humidity, that is, the environmental dependence of the electric resistance value was large, and the development characteristics were significantly impaired. . When silicone rubber is used as the elastic material, the environment resistance is very stable and the electrical resistance does not depend on the environment. However, unreacted low-molecular-weight siloxane and / or silicone oil causes the surface of the latent image carrier to Occasionally, it was contaminated and impaired the development characteristics. Therefore, an object of the present invention is to provide a semi-conductive roll which has stable triboelectric charging characteristics and developing characteristics without being contaminated with respect to a latent image carrier or having environmental dependence of electric resistance.

[0004]

The present invention has been completed as a result of earnest research by paying attention to the environment resistance of silicone rubber and fluororesin and the barrier property of fluororesin against low-molecular siloxane. The elastic roll is characterized in that an elastic semiconductor layer made of an electronically conductive silicone rubber and a semiconductive bleed prevention layer made of an electronically conductive fluororesin are sequentially laminated on the outer peripheral surface of the electrically conductive shaft. It is what In this semiconductive roll, the semiconductive bleed prevention layer is made of a fluororesin and an electron conductive filler having an average particle size of 1 to 10 μm, particularly conductive carbon black or a conductive metal oxide. Elongation of 10 to 100 μm
It is preferable that the volume resistivity is 50% or more and the volume resistivity is 10 ¹ to 10 ⁹ Ω · cm.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Next, details of the present invention will be described with reference to FIGS. 1 (a) and 1 (b). FIG. 1 (a) relates to a first embodiment of a semi-conductive roll, 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 layers 3 and 3 are semiconductive bleed preventing layers made of an electron conductive fluororesin formed on the elastic semiconductor layer 2a.
FIG. 1 (b) relates to a second embodiment of a semiconductive roll. In the semiconductive roll of FIG. 1 (a), 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 above semiconductive roll, the conductive shaft 1 has a so-called "core" made of iron, aluminum, SUS, brass, etc., as well as a thermoplastic resin and / or
Alternatively, an electrically conductive material obtained by plating the surface of an insulating core made of a thermosetting resin to make it conductive, a thermoplastic resin and / or a thermosetting resin mixed with carbon black as a conductivity-imparting agent, a metal powder, or the like. Core made of a flexible resin molded product, or a core made of a combination of these,
Any material selected from plastics, metals, and ceramics may be used as long as it is electrically conductive. The conductive shaft 1 is grounded at one end thereof or applied with a bias voltage to charge the electrostatic latent image carrier, inject charges into the toner, and carry the toner to the electrostatic latent image carrier by static electricity. It exerts functions such as developing a latent image.

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 and the like, fumed silica, precipitable silica and conductive material. Carbon black, metal powder, metal oxide, etc., or one or more of them are mixed in a desired ratio, and a vulcanizing agent such as a peroxide or a platinum catalyst, and if necessary, a blowing agent are added together. After kneading, it is heat-cured and cross-linked to obtain a solid product (2a) or a sponge product (2b) as illustrated. As a specific example of this, 100 parts by weight of organic peroxide-reactive silicone raw rubber and 6 parts by weight of carbon black
After adding 30 parts by weight and 10 to 35 parts by weight of fumed silica-based filler and kneading with a pressure kneader, an organic peroxide-based vulcanizing agent
Examples thereof include adding 2.0 parts by weight.

The elastic semiconductor layer 2 has a volume resistivity of 10 ¹
Generally, a material of ~ 10 ⁹ Ω · cm is used. If the amount is out of the above range, fog, transfer efficiency decrease, print density incompatibility and the like are likely to occur. The elastic semiconductor layer 2 is
It functions as an electrode for charging and developing processes, an electrode for contact charging and charge injection to toner, and a toner transporting process,
In the developing step, the surface of the roll is carried and conveyed by the unevenness of the surface and van der Waals force, image force, Coulomb force, and the like. The elastic semiconductor layer 2 has excellent environment resistance against temperature and humidity, and since it uses an electron-conductivity-conducting agent, the electrical resistance value has very little environmental dependence.

The electron conductive fluororesin used for forming the semiconductive bleed prevention layer 3 has a basic constitution of fluoroethylene vinyl ether copolymer, and an inorganic or organic compound having an average particle size of 1 to 10 μm as a conductivity imparting agent. The electronically conductive fillers of, for example, conductive carbon black, conductive zinc oxide, metal oxides such as conductive tin oxide and antimony oxide, and those which are made semi-conductive by adding powders of various metals are isocyanate-based. It can be obtained by crosslinking with a crosslinking agent of. 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 types of side chain functional groups of the vinyl ether unit, such as alkyl groups and alkylene groups. You can 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. 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, so 50%
It is preferable to adjust to the above elongation.

Average particle size in electronically conductive filler 1-10
The use of particles of μm is advantageous because the carrying force for the toner can be arbitrarily changed, and at the same time, a decrease in the toner carrying force with time due to abrasion can be suppressed.
When the average particle size of the filler is less than 1 μm, the surface roughness cannot be secured by simply adding and blending and molding, and the toner carrying force becomes inferior. It is necessary to use a mold having a surfaced cavity, or to perform post-processing (to secure surface roughness by sandblasting etc.) after molding. On the other hand, if the average particle size is
When it exceeds 10 μm, the toner carrying force is too large and the image is deteriorated.

The semiconductive bleed prevention layer 3 made of this electronically conductive fluororesin has a volume resistivity of 10 ¹ to 1 1.
Those having a resistance of ⁰⁹ Ω · cm, preferably 10 ³ to 10 ⁷ Ω · cm are generally used. If it is out of the range of 10 ¹ to 10 ⁹ Ω · cm, fogging, decrease in transfer efficiency, and incompatibility of print density are likely to occur. Semi-conductive bleed prevention layer 3 has a thickness of 10μ
If it is at least m, the bleeding prevention effect will be sufficient and 100
If the thickness is less than μm, the flexibility as a roll is sufficient and the printing characteristics are not deteriorated.
It is preferably 100 μm. The semiconductive bleed preventing layer 3 prevents the low molecular weight siloxane and / or silicone oil in the semiconductive silicone rubber layer from bleeding. This prevents the low-molecular-weight siloxane and / or silicone oil from adhering and / or migrating to the electrostatic latent image carrier and the toner, and a printed matter free from print defects, unevenness, and fog can be stably obtained. Further, the semiconductive bleed prevention layer 3 is
It has excellent environment resistance to temperature and humidity, and because it uses an electron-conducting conductivity-imparting agent, its electrical resistance has very little environmental dependence.

In the semiconductive roll of the present invention, 1) the conductive shaft and the electron conductive silicone rubber are integrally dispensed using a crosshead in an extruder, and then primary-added in a gear oven or an IR furnace. Sulfurizing method, 2) After setting the conductive shaft body in the mold, inject the silicone rubber composition,
It is formed into a roll by any processing method such as a method of primary vulcanization at room temperature or under heating, or 3) a method of simultaneously heating and compression molding the conductive shaft and the silicone rubber composition in a mold. After that, physical properties can be stabilized by secondary vulcanization for a certain period of time using a gear oven or the like. The obtained roll-shaped molded product, as it is, or as required, a cylindrical grinder, a shot blaster,
After making a desired surface condition with a sand blaster, a lapping machine, a buff, etc., the surface of this roll-shaped molded article is subjected to dipping, spray coating, an electron conductive fluororesin,
The semiconductive roll of the present invention can be obtained by applying the composition by roll coating or the like and then curing it by a method such as room temperature curing, heat curing, ultraviolet curing, or electron beam curing.

[0013]

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the description of these examples. Example 1 A SUM22 electroless nickel-plated shaft having a diameter of 10 mm and a length of 250 mm was used as a conductive shaft, and a silicone-based primer: primer No. 16 was used on the outer peripheral surface of the shaft.
(Trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied and baked in a gear oven at 150 ° C. for 10 minutes. As electronic conductive silicone rubber, 100 parts by weight of organic peroxide-reactive silicone raw rubber: KE-78VBS (same as above), 10 parts by weight of carbon black: thermal black (trade name of Asahi Carbon Co., Ltd.) and fumed silica Filler: Aerosil 200
(Nippon Aerosil Co., Ltd., trade name) 25 parts by weight was added, and after kneading with a pressure kneader, organic peroxide vulcanizing agent: C-8 (Shin-Etsu Chemical Co., Ltd. trade name) 2.0 parts by weight Was added, and the mixture was charged into a compression molding die consisting of a cylindrical cavity having an inner diameter of 20 mm, and vulcanization adhesion molding was performed with the above conductive shaft body at 175 ° C. for 10 minutes. After that, secondary vulcanization was performed in a gear oven at 200 ° C. for 7 hours and polished by 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 Lumiflon (trade name, manufactured by Asahi Glass Co., Ltd.) containing a fluorocarbon resin coating containing an isocyanate crosslinking agent was coated with tin oxide (antimony oxide dope) on the surface of titanium oxide powder having an average particle diameter of 0.2 μm. Electronically conductive filler: A mixture of 50 parts by weight of W-1 (trade name, manufactured by Mitsubishi Materials Corp.) is applied on the surface of the above roll-shaped molded product with a spray coating machine to a coating thickness of 30 μm, and a gear is applied. It was baked and cured in an oven at 150 ° C. for 30 minutes to obtain a semiconductive roll of the present invention.

On the other hand, as a developing device for visualizing the electrostatic latent image formed on the latent image carrier by the triboelectrically charged toner carried in a thin layer on the outer periphery of the developing roll, an electrophotographic image shown in FIG. Type printer was prepared, and a continuous printing test was conducted using the semi-conductive roll as the developing roll.
As a result, the fog and the print density were good even after printing 6,000 sheets. At the same time, microscopic observation of the surface of the developing roll was carried out, but no toner sticking was observed. In addition, the unused developing rolls, 2 kg each on both ends of the latent image carrier.
Abutting with force of f (4 kgf in total), 50 in the environmental tester
After left for 120 hours in an environment of 80 ° C. and 80% RH, the presence or absence of sticking to the latent image bearing member was confirmed. No sticking was observed and there was no alteration of the latent image bearing member. Then, this latent image bearing member was mounted on the electrophotographic printer, and a halftone dot and solid black printing test was carried out. As a result, a good printing state without print omission was obtained.

(Example 2 and Comparative Example) By the same method,
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, etc. were changed as shown in Table 1.
Was prepared. Further, using the above-mentioned roll-shaped molded product as it was as a developing roll as a comparative example, the following test items were measured together with Example 2, and the results are shown in Table 1.

(Test item) Roll resistance: A rubber roll before coating is placed on a gold-plated electrode that is 5 mm longer than the total length of the rubber, a weight of 500 g is applied to both ends of the rubber roll, and a voltage of 10 V is applied between the shaft and the surface of the rubber roll. In between, the resistance value was measured. -Membrane resistance value: After curing the fluororesin-based semiconductive coating agent 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 the tool microscope.・ Membrane elongation: 0.5 film thickness on tetrafluoroethylene plate
A semi-conductive fluororesin sheet cured with mm, JIS K 63
A tensile test was performed according to 01 and the elongation was measured.

White spots: After the semiconductive roll is brought into contact with and left on the photosensitive drum, the photosensitive drum is incorporated into an electrophotographic printer for halftone dot printing, and the presence or absence of printing abnormality at the contact portion is visually checked. confirmed. Judgment was made based on the presence or absence of the print density reduction portion in the halftone dot printing of the environmental tester, and if so-called white spots were observed even a little, it was regarded as a failure. Fog: A semi-conductive roll is incorporated into an electrophotographic printer, and black solid, halftone dots, 5% duty, white background printing are repeated, and the Macbeth density of the white area of the 5% duty image is measured using a Macbeth densitometer. It was measured. initial·
After the endurance test, the fog after 0.015 was rejected. -Print density: The Macbeth density of the solid black print portion printed by the same method as fog was measured using a Macbeth densitometer. If both the initial and post-durability concentrations were less than 1.3, they were rejected.

Toner fixation: After the durability test, the surface of the roll was observed with a microscope and fixation was observed. -Latent image carrier sticking: Those in which sticking was observed on the roll surface and the photosensitive drum surface after the environmental test were rejected. -Breakage of the film: The film after the durability test was observed with a microscope to confirm the presence or absence of a damaged portion.

[0019]

[Table 1]

(Evaluation of Results) Sample 1: Since the film thickness is 10 μm, the effect of preventing white spots is not seen, and since the elongation is less than 50%, the film is not flexible and is used for controlling the surface roughness. Print density after durability test is low because no filler is added.・ Sample 2: Since the film thickness is 10 to 100 μm and the elongation is 50% or more, white spots are prevented after the environmental test, and the printing density after the durability test is improved because a filler is added to control the surface roughness. Has been done. Sample 3: Since the film thickness exceeded 100 μm, the film durability and white spot prevention effect were enhanced, but the surface hardness also increased with this, and the toner transporting power decreased and the print density decreased.

Sample 4: Since the film thickness was 10 to 100 μm and the elongation was 50% or more, white spots were prevented after the environmental test and the durability of the film and the white spot prevention effect were recognized, but the roll resistance was
The print density was reduced because it exceeded 10 ⁹ Ω.・ Sample 5: Since the film thickness was 10 to 100 μm and the elongation was 50% or more, white spots were prevented after the environmental test and the durability and white spot prevention effect of the film were confirmed, but for controlling the surface roughness. Fog increased because the particle size of the filler exceeded 10 μm.・ Sample 6: Since the film thickness is 10 to 100 μm and the elongation is 50% or more, white spots are prevented after the environmental test and the durability and white spot prevention effect of the film are recognized, but for controlling the surface roughness. Since the particle size of the filler was less than 1 μm, the print density was lowered.

[0022]

In the semiconductive roll of the present invention, the outermost layer is provided with a semiconductive bleed preventing layer made of an electronically conductive fluororesin, so that low molecular weight siloxane and / or silicone oil in silicone rubber can be used. The bleeding of the liquid material is prevented, the latent image carrier or the toner is not fixed or transferred, and it is possible to prevent the occurrence of print omissions and unevenness. Further, since the density of the black solid at that time depends on the state of the unevenness of 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. . Furthermore, since the elastic semiconductive layer is an electron conductive silicone rubber and the semiconductive bleed prevention layer is an electron conductive fluororesin, there is no hydrolysis due to moisture in the air, fixing to the latent image carrier and toner. There is no sticking. In addition to such characteristics, when the electron conductivity-imparting agent of the electron conductive silicone rubber and the electron conductive fluororesin is conductive carbon black or conductive metal oxide, the dependence of electric resistance on temperature and humidity is determined. There is almost no property, and stable printing characteristics can always be obtained.

[Brief description of drawings]

FIGS. 1A and 1B are cross-sectional explanatory views illustrating different embodiments of a semiconductive roll of the present invention.

FIG. 2 is an explanatory cross-sectional view of an electrophotographic printer used in Examples.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Conductive shaft, 2a ... Solid elastic semiconductor layer, 2
b ... Sponge-like elastic semiconductor layer, 3 ... Semi-conductive bleed preventing layer, 10 ... Photosensitive drum, 11 ... Charging roll, 12 ... Developing roll, 13 ... Toner conveying roll, 14 ... Transfer roll, 15 ... Cleaning roll, 16 ... agitator, 17 ... friction charging blade, 18 ... LED array, 19 ... container, 20 ... recording paper.

Claims (2)

[Claims] 1. An elastic semiconductor layer made of electronically conductive silicone rubber and a semi-conductive bleed prevention layer made of electronically conductive fluororesin are sequentially laminated on the outer peripheral surface of a conductive shaft. Characteristic semi-conductive roll. 2. A semi-conductive bleed prevention layer comprising a fluororesin and an electron conductive filler having an average particle size of 1 to 10 μm, a thickness of 10 to 100 μm and an elongation of 50% or more, and a volume resistivity value. The semiconductive roll according to claim 1, wherein the semi-conductive roll has a viscosity of 10 ¹ to 10 ⁹ Ω · cm.