JP2001290362A - Semiconducting sponge roll and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconducting sponge roll and a developing device using the roll which are excellent in the electrifying properties of a toner, toner carrying properties, and toner release properties from the sponge roll, with which stable and good printing density is obtained and with which a high-quality printed image can be obtained without causing printing failure such as negative afterimage, positive afterimage and fog or jitter. SOLUTION: The semiconducting sponge roll is used for a developing device to visualize an electrostatic latent image formed on a latent image carrying body with a triboelectric toner and has a conducting axial body and an elastic semiconducting layer around the body. The coefficient of kinetic friction (μ) of the surface of the semiconducting sponge roll is specified to from 0.1 to 1.2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductive sponge roll used as a toner conveying roll, a transfer roll, and a cleaning roll in a developing device of an electrophotographic system or the like, and a developing device provided with the same.

[0002]

2. Description of the Related Art In a developing apparatus such as an electrophotographic system for visualizing an electrostatic latent image formed on a latent image carrier using a triboelectrically charged toner, a semiconductive sponge is used for a toner conveying roll, a transfer roll and a cleaning roll. Rolls are used. This semi-conductive sponge roll has a conductive shaft and an elastic semi-conductive layer located around the conductive shaft, and is functionally conductive, has environmental resistance, low hardness, triboelectricity, toner transportability, etc. Characteristics are required. For such a request,
Conventionally, urethane rubber sponge, silicone rubber sponge, ethylene-propylene-diene rubber (hereinafter referred to as EPD)
M sponge) is used as a material, and a semiconductive sponge roll having an elastic semiconductive layer formed by adding an ion conductive material or an electron conductive material as a conductivity imparting agent to the material is well known. As a conductivity-imparting agent for controlling the conductivity of the semiconductive sponge roll, a compound such as a resin or rubber filled with carbon black, conductive metal particles, metal oxide particles, and the like is used.

[0003] In addition to the above-mentioned characteristics, excellent printing characteristics in the initial stage and over time are required for the toner conveying roll, the transfer roll, and the cleaning roll used in a developing device such as an electrophotographic system. The printing characteristics include, in particular, the level of negative and positive afterimages indicating independence with respect to the printing history, in addition to the print density caused by toner transportability, the reproducibility of fog and fine lines caused by toner chargeability, and the like.

[0004]

A conventional semiconductive sponge roll, for example, in the case of a toner transport roll, comprises an elastic semiconductive layer made of a urethane rubber sponge or an EPDM sponge to reduce hardness. Damage to the toner is reduced. However, such a semiconductive sponge roll tends to cause a decrease in the ability to impart charge to the toner, resulting in an increase in fogging and a partial density decrease due to a print history of a negative afterimage. There was a problem that it was easy. Further, when the elastic semiconductive layer of the semiconductive sponge roll, for example, is configured by open-celled urethane rubber sponge,
The toner enters the bubbles of the urethane rubber sponge,
A phenomenon referred to as clogging occurs, causing an increase in the hardness of the elastic semiconductive layer and a decrease in the ability to impart a charge to the toner, thereby causing an increase in fog and a decrease in the toner transport ability. In order to solve such a problem, it has been proposed that the elastic semiconductive layer is formed of, for example, a silicone rubber sponge, which has a higher charging ability to the toner than a urethane rubber sponge or an EPDM sponge. In this case, since the damage to the toner is reduced and the charge amount of the toner is increased, a high-quality image without fog can be obtained. However, when the elastic semiconductive layer is used for a long period of time, the abrasion of the elastic semiconductive layer is severe, and the ability to impart charge to the toner and the amount of toner transported are likely to be reduced. Therefore, when the hardness of the elastic semiconductive layer is increased to reduce the wear of the elastic semiconductive layer, the frictional force with the developing roll increases, the rotational load increases, and the vibration in the rotational direction increases. (Hereinafter referred to as "jitter").

The present invention solves the above-mentioned conventional problems, and is excellent in toner chargeability, toner transportability, and toner releasability from the semiconductive sponge roll, and has a stable print density. Is obtained, negative afterimage, positive afterimage,
An object of the present invention is to provide a semiconductive sponge roll which does not cause printing failure and jitter due to fog or the like, and a developing device using the sponge roll.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the dynamic friction coefficient (μ) of the surface of the semiconductive sponge roll should be within a predetermined range. Based on such knowledge, the present invention has been completed. That is, the present invention uses a triboelectrically charged toner, used in a developing device for visualizing an electrostatic latent image formed on a latent image carrier, a conductive shaft and an elastic semiconductive layer located therearound, preferably Is a semiconductive sponge roll comprising an elastic semiconductive layer comprising a sponge having closed cells, wherein the coefficient of dynamic friction (μ) of the surface of the semiconductive sponge roll is 0.1 to 1. 2 and a developing device using this semiconductive sponge roll.

[0007]

Next, the present invention will be described in detail with reference to the drawings. As described above, the feature of the semiconductive sponge roll of the present invention resides in that the dynamic friction coefficient (μ) of the surface of the semiconductive sponge roll is set to 0.1 to 1.2. Thereby, the toner chargeability, the toner transportability, and the toner releasability from the semiconductive sponge roll are improved,
Good print density can be obtained stably, and printing defects and jitters due to negative afterimages and positive afterimages can be suppressed, and high-quality printed images free from printing defects can be obtained for a long time. Specifically, the level of the print history is the difference in Macbeth density.
0.01 and -0.05 to +
0.05 is possible.

The semiconductive sponge roll of the present invention comprises a conductive shaft 1 and an elastic semiconductive layer 2 located around the conductive shaft. 3, a coating material layer 4 made of rubber or resin can be provided. FIGS. 1A, 1B, and 1C are cross-sectional views illustrating semiconductive sponge rolls having different modes. Although not illustrated in FIG. 1, the present invention includes a structure in which the coating material layer 4 is provided on the high crosslinking density layer 3 and a structure in which two or more coating material layers 4 are provided. The coefficient of kinetic friction (μ) of the surface of the semiconductive sponge roll was measured using a friction tester (HEIDON 3K-34B / HEIDON-14, shown in FIG. 2).
It is measured using Shinto Kagaku Co., Ltd. (trade name). Specifically, the semiconductive sponge roll 10 to be measured is set on the V-block 11 of the tester, and a 100 g weight 1 is set.
2 and a vertical load of 600 mm /
The semi-conductive sponge roll 10 is moved in the direction indicated by the arrow at a speed of
The sample was rubbed with an eye (width 50 mm, manufactured by Ricoh Company, trade name), and the dynamic friction coefficient (μ) was measured. Note that, in FIG.
Represents a load cell.

The conductive shaft 1 is a support for the elastic semiconductor layer 2 formed on the outer periphery thereof. One end of the conductive shaft 1 is grounded or a bias voltage is applied to charge the electrostatic latent image carrier and apply toner. Charge, toner adsorption, toner transfer to the developing roll surface, and toner transfer from the developing roll surface to the electrostatic latent image carrier to obtain electrostatic latent image development, charging and transfer performance. it can. Although the material of the conductive shaft 1 is not particularly limited, a so-called “core” made of a conductive metal such as iron, aluminum, SUS, or brass, or a thermoplastic resin and / or A core obtained by subjecting a core of a curable resin to metal plating, a core obtained by mixing a thermoplastic resin and / or a thermosetting resin with a carbon black, a metal powder, or the like as a conductivity-imparting material is used.

The elastic semiconductive layer 2 is a sponge of one or more layers composed of an elastomer composition, and includes an electrode for forming an electric field for transporting the toner to the surface of the developing roll, contact charging to the toner, It acts as an electrode for charge injection and forms a uniform electric field with the developing roll by the mechanical transport force of the sponge holes on the surface and the electrostatic force of the toner due to contact charging, and at the same time electrostatically Conveys toner. The material of the elastic semiconductive layer 2 is not particularly limited, but may be silicone rubber,
Ethylene-propylene-diene rubber, polyurethane, chloroprene rubber, natural rubber, butyl rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, nitrile rubber, ethylene-propylene rubber, acrylic rubber, etc .; Fillers such as precipitated silica and reinforcing carbon black, conductive carbon black, metal powders such as nickel, aluminum and copper, metal oxides such as zinc oxide and tin oxide, barium sulfate, titanium oxide and potassium titanate, etc. A conductive filler coated with tin oxide on the core material of the compound, and the like, to further form a sponge, azo compound-based, bicarbonate-based, isocyanate-based, nitrite, hydrazine derivative, azide compound-based foaming agent and the like Peroxide is added to at least one foaming agent. Or siloxane platinum catalyst presence, isocyanate, elastomer composition obtained by kneading together a crosslinking agent such as sulfur-based vulcanizing agent is exemplified. The elastic semiconductive layer 2 is preferably a sponge having closed cells. By using closed cells, mechanical properties such as tensile strength and elongation are improved, and an increase in fog and a decrease in toner transport ability are suppressed, so that good printing characteristics can be obtained.

A highly crosslinked density layer 3 can be provided on the elastic semiconductive layer 2 by irradiating ultraviolet rays, electron beams, particle beams, or the like, or a coating material layer 4 made of resin or rubber can be provided. By providing an appropriate high crosslink density layer 3 and / or a coating material layer 4, the chargeability of the toner can be controlled, and both the releasability of the toner and the abrasion resistance of the elastic semiconductive layer 2 can be improved. Can be. That is, it is possible to improve the stability over time of imparting chargeability to the toner and increase the mechanical transportability of the toner. The material of the coating material layer 4 is not particularly limited, but a resin or rubber having an amino group and / or a hydroxyl group is preferable. For example, alkyd resins, modified alkyd resins such as phenol-modified and silicone-modified, oil-free alkyd resins, acrylic resins, silicone resins, epoxy resins, fluororesins, phenol resins, polyamide resins, urethane resins and their silicone-modified, amino-modified, etc. And modified mixtures thereof. To crosslink these, a crosslinking agent such as an isocyanate compound, a melamine compound, an epoxy compound, a peroxide, a phenol compound, and a hydrogensiloxane compound is used.

The semiconductive sponge roll of the present invention is obtained by forming an elastic semiconductive layer 2 by forming an elastomer composition on a conductive shaft 1 under appropriate conditions into a roll, and then forming a desired surface condition. It is obtained by finishing. In forming the semiconductive sponge roll, the conductive shaft 1 and the elastomer composition are integrated and separated using a crosshead using an extruder, and then primary-processed in a gear oven or an IR furnace (infrared heating furnace). Vulcanization method, a method of setting the conductive shaft 1 in a mold, injecting an elastomer composition and performing primary vulcanization at room temperature or under heating, and simultaneously charging the conductive shaft 1 and the silicone rubber composition in the mold. After heating and compression molding,
A method of demolding and foaming in a gear oven or the like is used. After molding by these methods, the physical properties can be stabilized by further performing secondary vulcanization for a certain period of time in a gear oven or the like. In order to obtain the closed cell elastic semiconductive layer 2, for example, a foaming agent having a rapid gas generation characteristic such as an azo compound-based foaming agent or an azide compound-based foaming agent may be used. The obtained molded product is processed into a cylindrical shape by an outer diameter processing machine such as a cylindrical grinder or a laser processing machine as necessary, and is formed into a roll shape. Thereafter, if desired, a high crosslinking density layer 3 is provided on the surface of the elastic semiconductive layer 2 by irradiating ultraviolet rays, an electron beam, a particle beam, or the like, or a coating material layer 4 is provided by uniformly applying a protective coating material. . The coating material layer 4 may be a coating material containing only the resin or the elastomer, but is formed by adding a conductive powder or an ion-conductive substance to the resin or the elastomer to make the coating material itself semiconductive. Is preferred.

FIG. 3 schematically shows an electrophotographic printer as an example of a developing device using the semiconductive sponge roll of the present invention. A photosensitive drum 20 as an electrostatic latent image carrier is provided inside the housing 26. After uniformly charging the surface of the photosensitive drum 20, the charging roll 21 irradiates LED light from the LED array 25 to form an electrostatic latent image on the surface of the photosensitive drum 20. This electrostatic latent image is
The image is visualized by the toner carried on the surface of the developing roll 22, and is transferred to the recording paper 27 by the transfer roll 29. The toner in the toner container is transported onto the toner transport roll 28 by the stirrer 23, and is further triboelectrically charged with the developer roll 22 by the toner transport roll 28 and simultaneously electrostatically attracted onto the developer roll 22, further,
The toner is uniformly charged by the frictional charging blade 24. The semiconductive sponge roll of the present invention comprises a toner transport roll 2
8, a transfer roll 29 and a cleaning roll 30 for removing residual toner adhering to the photosensitive drum 20. When the semiconductive sponge roll of the present invention is used as a toner transport roll, the volume specific resistance of the toner transport roll is generally preferably set to 10 ¹ to 10 ⁹ Ω · cm. If the volume resistivity is out of the above range, problems such as inconsistency in print density due to a decrease or increase in toner transportability to the developing roll, and fogging due to inconsistency in toner charge amount are likely to occur.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

(Embodiment 1) SUM2 is used as a conductive shaft.
2 with electroless nickel plated diameter 10mm, length 2
Primer No., which is a silicone-based primer, was placed on a 50 mm shaft. No. 16 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied and baked at 150 ° C. for 10 minutes in a gear oven. Further, 100 parts by weight of methyl vinyl silicone raw rubber: KE-78 VBS (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) and 100 parts by weight of dimethyl silicone raw rubber: KE-76 VBS (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.)
0 parts by weight, carbon black: Asahi Thermal (Asahi Carbon Co., Ltd., trade name) 10 parts by weight, fumed silica filler:
Aerosil 200 (Nippon Aerosil Co., Ltd., trade name) 15
Parts by weight, blowing agent: KE-P13 (manufactured by Shin-Etsu Chemical Co., Ltd., 4 parts by weight), platinum catalyst: C-19A (manufactured by Shin-Etsu Chemical Co., Ltd.)
Product name) 0.5 part, hydrogen siloxane: C-1
A silicone rubber composition prepared by adding 2.4 parts of 9B (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) and kneading with a pressure kneader was used. Next, the silicone rubber composition was integrated with the conductive shaft using an extruder using a crosshead, and then the mixture was heated and vulcanized at 300 ° C. for 15 minutes in a gear oven. And vulcanized adhesive molding. Thereafter, secondary vulcanization is performed at 200 ° C. for 4 hours in a gear oven, polished with a cylindrical grinder, and irradiated with ultraviolet light (integrated light amount of 254 nm wavelength: 10 J / cm ² ) in air by a low-pressure mercury lamp to obtain a crosslink density of the surface. To a high density, 16mm in diameter,
Rubber part length 210mm, hardness 70 ° (ASKER
A semiconductive sponge roll of F) was obtained.

(Example 2) Instead of irradiating the surface of the formed roll with ultraviolet rays, a urethane-based paint: Nipporan 3
022 (manufactured by Nippon Polyurethane Co., Ltd., trade name), 100 parts by weight of a polyisocyanate crosslinking agent: Coronate-L
(Nippon Polyurethane Co., trade name) After adding 5 parts by weight, spray-coating, and heat-curing at 150 ° C. for 30 minutes, processing was performed under the same conditions and method as in Example 1 to obtain a rubber having a diameter of 16 mm Part length 210mm, hardness 7
A semiconductive sponge roll of 0 ° (ASKER F) was obtained.

(Example 3) Instead of irradiating the surface of the formed roll with ultraviolet rays, a fluorine latex paint: GL
To 100 parts by weight of -152 A liquid (manufactured by Daikin Industries, Ltd.), 5 parts by weight of a cross-linking agent: GL-152 B liquid (manufactured by Daikin Industries, Ltd.) was added and spray coated. Except for heating and curing for 30 minutes, a treatment was carried out under the same conditions and method as in Example 1, and a diameter of 16 mm
Rubber part length 210mm, hardness 70 ° (ASKER
A semiconductive sponge roll of F) was obtained.

(Comparative Example 1) A treatment was carried out under the same conditions and in the same manner as in Example 1, except that the surface of the formed roll was not irradiated with ultraviolet rays, and had a diameter of 16 mm and a rubber part length of 210 m.
m, a semiconductive sponge roll having a hardness of 70 ° (ASKER F) was obtained.

(Comparative Example 2) Instead of irradiating the surface of the formed roll with ultraviolet rays, a fluorine latex paint: GL
S-213 Liquid A (product name, manufactured by Daikin Industries, Ltd.) 100
5 parts by weight of a crosslinking agent: GLS-213 B solution (trade name, manufactured by Daikin Industries, Ltd.) was added to 5 parts by weight, spray-coated, and then heat-cured at 150 ° C. for 30 minutes, except that
The treatment was performed under the same conditions and under the same conditions as in Example 1 to obtain a
m, rubber length 210mm, hardness 70 ° (ASKER
A semiconductive sponge roll of F) was obtained.

(Printing Test) Examples 1 to 4 were prepared using commercially available electrophotographic printers using negatively charged toner or positively charged toner.
3 and the semiconductive sponge rolls obtained in Comparative Examples 1 and 2 were mounted as toner transport rolls, and printing tests were performed for the following items. The results are shown in Table 1. In Table 1, "Initial" means the use of a semiconductive sponge roll immediately after the start of use, and "Durable" means the use of a semiconductive sponge roll after printing 6,000 sheets. -Dynamic friction coefficient (μ) Friction tester shown in Fig. 2 (HEIDON 3K-34B / HEIDON
-14, manufactured by Shinto Kagaku Co., Ltd.), a semiconductive sponge roll was set on the V-block of the above-mentioned tester, a weight of 100 g was used as a vertical load, and the slide was rotated 60 times.
Move in the direction of the arrow at a speed of 0 mm / min, and use a PPC paper (RICHO 6200 A4T mesh (width 50 mm), manufactured by Ricoh
(Trade name), and the kinetic friction coefficient (μ) in the tangential direction to the outer peripheral surface of the semiconductive sponge roll was measured. -Amount of toner adhered While the printer was printing at 5% duty, the power of the printer was turned off, and the toner layer of the untransferred portion on the photosensitive drum was peeled off using a cellotape (registered trademark) peeling method.
The toner adhesion amount per unit area was measured using an electronic balance. Roll resistance Each semiconductive sponge roll is placed on a gold-plated electrode that is 5 mm longer than its entire length, a weight of 500 g is applied to each end of the sponge roll, and a voltage of 100 V is applied between the shaft and the surface of the sponge roll. , And the resistance value at that time was measured.・ Initial print density, post-durability print density Semi-conductive sponge roll is incorporated into the above printer,
Black solid, halftone dots, 5% duty, white background printing, etc. were repeated, and the Macbeth density of the black solid printed portion was measured using a Macbeth densitometer.・ Initial fog, endurance fog Semi-conductive sponge roll is incorporated into the above printer,
Black solid, halftone dots, 5% duty, white background printing, etc. were repeated, and the Macbeth density of the 5% duty, white background was measured using a Macbeth densitometer.・ Negative afterimage, positive afterimage Incorporate semiconductive sponge roll into the above printer,
Black solid printing, black solid printing, 5% duty, white background printing, etc. are repeated, and a black solid printing part and a black solid printing of a test print pattern in which a black solid printing part is provided behind a black square printing of 10 mm in width and 34.9 mm in length. The Macbeth density of the black solid printing portion immediately after the printing of the black square printing (= non-printing portion) was measured using a Macbeth densitometer, and the difference was regarded as an afterimage.・ Initial black solid unevenness, black solid unevenness after endurance
Black solid, halftone dots, 5% duty, white background printing, etc. were repeated, and the presence or absence of print density unevenness in the solid black portion was visually determined. -Toner fixation The surface of the semiconductive sponge roll after the endurance test was observed under a microscope to determine the presence or absence of toner fixation.

The pass / fail judgment was made based on the following criteria. When all of the following items passed, the result was evaluated as ○, and when any of the items failed, the result was evaluated as ×. -Print density Both initial and endurance Macbeth densities less than 1.3 were rejected.・ Fog Both initial and endurance Macbeth densities exceeding 0.015 were rejected. -Afterimage For negative afterimages, the acceptable range was -0.05 to 0.01, and for positive afterimages, the acceptable range was -0.05 to 0.05. -Black solid unevenness Any black solid density that was uneven both at the initial stage and after running was rejected.・ Toner fixation After semi-conductive sponge roll surface after microscopic observation,
Those with toner sticking were rejected.

(Results of Printing Test) In Examples 1 to 3, as a result of confirming the printing characteristics after printing 6000 sheets from the initial printing, there was no generation of negative and positive afterimages. A high quality printed image was obtained in image characteristics. Microscopic observation of the surface of the semiconductive sponge roll revealed no abnormalities such as toner adhesion, deterioration of the roll material, clogging, and jitter. Further, a printing test was performed on the transfer roll and the cleaning roll in the same manner as described above. As a result, good printing characteristics were obtained in each case. Further, with respect to the elastic semiconductive layer of the semiconductive sponge roll, better printing characteristics were obtained with the closed cell sponge than with the open cell sponge.

[0023]

[Table 1]

[0024]

The semiconductive sponge roll of the present invention is excellent in toner chargeability, toner transportability and toner releasability from the semiconductive sponge roll, and provides a stable and good print density. High quality printed images can be obtained without causing printing defects and jitters due to negative afterimages, positive afterimages, fog and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a semiconductive sponge roll of the present invention.

FIG. 2 is an explanatory view showing a method for measuring a dynamic friction coefficient of a semiconductive sponge roll surface.

FIG. 3 is a schematic view illustrating an example of an electrophotographic developing device.

[Explanation of Codes] Conductive shaft 20. 1. photosensitive drum 21. Elastic semiconductive layer (sponge) Charging roll 3. High crosslink density layer 22. Developing roll Coat material layer 23. Stirrer 10. Semiconductive sponge roll 24. Friction charging blade 11. V-block 25. LED array 12. Weight 26. Housing 13. Slide 27. Recording paper 14. PPC paper 28. Toner transport roll 15. Load cell 29. Transfer roll 30. Cleaning roll

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G03G 15/16 103 G03G 15/16 103 21/10 C08L 21:00 // C08L 21:00 G03G 21/00 312 (72) Inventor Kazuya Nakada 300, Toyohara, Motohara, Kanagawa-cho, Kodama-gun, Saitama 5-5 Inside the Kodama Plant, Shin-Etsu Polymer Co., Ltd. Site 5 Shin-Etsu Polymer Co., Ltd. Kodama Plant F-term (reference) 2H032 AA05 BA19 2H034 BC02 BC03 BC04 2H077 AC04 FA12 FA16 FA22 FA25 3J103 AA02 AA13 AA14 AA15 AA23 AA32 AA33 AA51 BA41 FA06 FA07 FA14 FA18 GA03 GA57 GA74 GA60 HA05 HA11 HA12 HA15 HA18 HA20 HA22 HA32 HA53 HA55 4F074 AA06 AA08 AA09 AA12 AA13 AA14 AA25 AA48 AA78 AA90 AA97 AC02 AC05 AC07 AC17 AC32 BA02 BA03 BA04 BA12 BA13 BA14 BA15 BA17 BA18 BA19 CA23 DA59

Claims (3)

[Claims] 1. A conductive shaft body and an elastic semiconductive layer located around the shaft, which are used in a developing device for visualizing an electrostatic latent image formed on a latent image carrier with a triboelectric toner. A semiconductive sponge roll, wherein the coefficient of dynamic friction (μ) of the surface of the semiconductive sponge roll is 0.1 to 1.
2. A semi-conductive sponge roll, wherein 2. The printing history level is a difference of Macbeth density, and is -0.05 to 0.01 for a negative afterimage and -0.05 to 0.05 for a positive afterimage. 2. The semiconductive sponge roll according to 1. 3. A developing device comprising the semiconductive sponge roll according to claim 1.