JP2002278265A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device which prevents toner filming and cohering body sticking on the surface of a thin layer roller, improves electrostatic charging characteristics of toner, and evades reverse electrostatic charging ground staining and an image forming device which can obtain an image of high picture quality. SOLUTION: The developing device has a developing roller which is arranged opposite an image carrier carrying an electrostatic latent image and supplies toner to the electrostatic latent image, a toner supply roller which electrostatically charges the toner by friction while supplying the toner onto the developing roller as a toner carrier, and a rotatable thin layer roller which restricts a toner thin layer formed around the toner carrier to uniform layer thickness and is characterized by that at least the surface of the thin layer roller is formed of a material made principally of cyclic polyolefin. The material may contains a compound and polyethylene wax which have a friction electrostatic charging series positioned more on the positive electrostatic charging side than the cyclic polyolefin. The volume resistance of the thin layer roller surface layer is preferably <=10<12> Ω.cm and the developing roller may have an elastic layer. The image forming device is equipped with the developing device, respective devices for electrostatic charging, exposure, transfer, cleaning, and destaticization, and an electrophotographic sensitive body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for visualizing an electrostatic latent image in an electrophotographic apparatus or an electrostatic recording apparatus, and an image forming apparatus capable of obtaining a high-quality image using the developing apparatus. About.

[0002]

2. Description of the Related Art Various developing devices using a non-magnetic one-component developer (hereinafter referred to as toner) have been proposed. As a general configuration of such a developing device, there is a developing device as shown in FIG. In this developing device, a developing roller as a developer carrier and a supply roller as a developer supply member are provided in sliding contact with each other, and the development roller and the supply roller are rotationally driven by a driving source. The supply roller serving as the toner supply member is generally made of a sponge material.

The toner in the developing device is conveyed by an agitator, supplied to a developing roller by a supply roller, charged by a sliding contact between the developing roller and the supply roller, and adheres to the developing roller. An elastic developing blade, such as a thin metal plate, is pressed against the surface of the developing roller to which the toner adheres, and the toner on the developing roller is thinned. The toner on the developing roller develops the electrostatic latent image on the photosensitive drum in a developing region between the image carrier including the photosensitive drum and the developing roller.

[0004] With this developing device, a developing device using a non-magnetic one-component developer can be easily configured. However, there are the following problems.

In this developing device, the toner layer on the developing roller is regulated by thinning the toner adhering to the surface of the developing roller by the developing blade. When the toner layer is regulated, the toner is melted at the sliding contact point between the developing roller and the supply roller and adheres to the developing blade, so-called toner sticking occurs.

[0006] With a developing blade in which toner sticking has occurred, a normally charged toner cannot be transported to a developing area by a predetermined amount, and a defective image is formed. For this reason, even if the durability of the functional components such as the developing roller is improved, the life of the developing device is governed by the adhesion of the toner, and the life of the developing device cannot be extended.

To solve such a problem, FIG.
As shown in JP-A-63-364, there has been proposed a developing device in which a thin layer roller rotated in the same direction as a developing roller by a driving source is brought into contact with the developing roller instead of the developing blade. Gazette).

Here, the rotation speed of the developing roller is set to a predetermined speed that satisfies the development conditions, and the rotation speed of the thin layer roller is set so that the thin layer roller rotates at a very low speed.
In this developing device, the thin layer roller for thinning the toner adhered to the surface of the developing roller does not contact the developing roller at only one place, and the thin layer roller rotates to develop the thin layer roller. Since the position of contact with the roller (toner carrier) changes, toner sticking to the thin layer roller is less likely to occur as compared with the developing blade, and a longer life has been expected.

[0009]

In the developing device using the above-mentioned thin layer roller, in order to extend the service life, a problem occurs due to toner aggregates generated inside the developing device as the developing device is used. There was a problem that would.

That is, the supply roller as the toner supply member is generally made of a sponge material. However, when the developing roller and the supply roller repeatedly slide and contact with each other due to the use of the developing device, one of the sponges constituting the supply roller is used. The part is torn off and circulates in the developing device together with the toner as minute foreign matter. When the developing device is used for a long period of time, when the toner is slid in contact between the developing roller and the supply roller or the thin layer roller, the toner adheres to the above-mentioned broken sponge, and the toner contacts with each other at the sliding contact portion. May be melted or toner aggregates may be generated.

The generated toner aggregates reach the vicinity of the sliding contact between the developing roller and the thin layer roller along the normal flow of the toner. The thin layer roller rotates in the same direction as the developing roller to thin the toner adhered to the surface of the developing roller, but the rotation speed of the developing roller is set to a predetermined speed that satisfies the developing conditions. The speed is set so that the thin layer roller rotates at a very low speed.

For this reason, the toner agglomerate that has entered the wedge-shaped portion at the entrance of the sliding contact portion between the developing roller and the thin layer roller is returned to the developing device without entering the sliding contact portion, or the toner is brought into contact with the sliding contact portion. Will enter. The toner aggregates entering the sliding contact portion are used for developing the electrostatic latent image to generate an abnormal image, or stay in the sliding contact portion and firmly adhere to the surface of the thin layer roller, and a thin layer is not formed. Creating a part will cause white streaks in the image.

Further, if the developing device is continuously used with toner agglomerates in the sliding contact portion between the developing roller and the thin layer roller, the surface of the developing roller or the thin layer roller in contact with the toner agglomerates deteriorates. As a result, a desired toner thin layer cannot be obtained on the developing roller. For this reason, it is necessary to improve the toner releasability of the thin layer roller and to prevent the aggregates from adhering to the surface of the thin layer roller.

In addition, not only agglomerates but also toner filming in which the toner is melted and fixed in the form of a thin film on the surface of the thin layer roller occurs, and although the durability is increased as compared with the developing blade, the toner on the surface of the thin layer roller is increased. It has been desired to further improve the releasability.

As a means for solving the above-mentioned problems, a method of providing a fluororesin having excellent toner releasability on the surface of a thin layer roller has been adopted. This can be manufactured, for example, by attaching a fluororesin tube to the surface of the thin-layer roller in addition to applying the fluororesin paint by a usual method such as spraying or a roll coater.

However, although the fluororesin has a very good releasability and solves the above-mentioned disadvantages, the frictional charge series is extremely located on the negative charge side. Therefore, when the toner thin layer is not uniformly formed, or when the F content is reduced to improve the chargeability of the toner, the toner releasability is deteriorated.

According to the present invention, toner filming and adhesion of agglomerates on the surface of a thin layer roller do not occur during long-term use.
It is another object of the present invention to provide a developing device having improved toner charging characteristics.

Still another object of the present invention is to provide a developing device which generates a small amount of reversely charged toner.

The following objects of the present invention will be described. In general, when developing toner on an electrostatic latent image carrier, a method of developing the developing roller and the electrostatic latent image carrier in a non-contact manner and a method of developing by contacting the developing roller are roughly classified. It is common to use elastic and rigid materials. Usually, a belt-shaped electrostatic latent image carrier is used for contact development, and a rigid developing roller is often used for non-contact development.

At that time, in order to secure an appropriate sliding contact portion between the thin roller and the developing roller, an appropriate elasticity is required on the thin roller side. However, if the rubber roller is used as it is, the toner releasability is poor. Therefore, it is general to provide a surface layer and improve it. However, if the flexibility is increased to follow the elasticity of the rubber layer, the releasability deteriorates. However, there is a problem that the above-described problem occurs.

A second object of the present invention is to provide a developing apparatus which does not cause toner filming or agglomerate adherence on the surface of a thin layer roller having elasticity, and which can prevent reverse charging background stain. is there.

Another object of the present invention is to provide a thin-layer roller having a low surface friction coefficient and a very small variation in friction coefficient with time.

Still another object of the present invention is to provide an image forming apparatus capable of obtaining a high-quality image free from image background contamination.

[0024]

According to the present invention, there is provided a developing roller which is arranged opposite to an image carrier for carrying an electrostatic latent image and supplies toner to the electrostatic latent image, and a developing roller which serves as a toner carrier. A toner supply roller that supplies the toner to the toner and simultaneously triboelectrically charges the toner, and a rotatable thin layer roller that regulates the toner thin layer formed around the toner carrier to a uniform thickness. Further, there is provided a developing device, wherein at least the surface of the thin layer roller is made of a material mainly composed of a cyclic polyolefin.

According to the present invention, there is provided the above-mentioned developing apparatus, wherein the material mainly composed of the cyclic polyolefin contains a compound whose triboelectric series is located on the positively charged side of the cyclic polyolefin. .

The present invention provides the above-mentioned developing device, wherein the volume resistance of the surface layer of the thin layer roller is 10 ¹² Ω · cm or less.

According to the present invention, there is provided the above-mentioned developing device, wherein the developing roller has an elastic layer.

The present invention provides the above-mentioned developing device, wherein the material mainly composed of the cyclic polyolefin contains a polyethylene wax.

According to the present invention, there is provided any one of the above developing devices,
There is provided an image forming apparatus including a charging device, an exposure device, a transfer device, a cleaning device, a charge removing device, and an electrophotographic photosensitive member.

Next, the thin layer roller used in the developing device of the present invention will be described. At least the surface of the thin layer roller used in the developing device of the present invention is made of a material mainly composed of a cyclic polyolefin.

The cyclic polyolefin is a polymer having a cyclic olefin as a main component and bonded in a main chain, and changes the crystallinity of the polymer by a linear olefin to amorphous.
In addition, it refers to all generally known materials having higher transparency, lower birefringence, heat resistance, chemical resistance and the like.

The polymer is well known as a cyclic olefin, and a practically used one is norbornene. A single cyclic polyolefin obtained by subjecting norbornene itself to ring-opening polymerization and hydrogenation, norbornene and ethylene, etc. And copolymerized cyclic polyolefins obtained by addition polymerization with a linear olefin. Known as single cyclic polyolefins are "ARTON" (trademark) marketed by Nippon Synthetic Rubber Co., Ltd. and "ZEONEX" (trademark) marketed by Zeon Corporation. "Apel" (trademark) marketed by Mitsui Chemicals, Inc.

[0033] The cyclic polyolefin used in the present invention can be blended with other polymers as required. Other polymers include, for example, rubbery polymers and other thermoplastic resins.

Examples of the rubbery polymer include polybutadiene rubber, polyisoprene rubber, acrylonitrile
Diene rubbers such as butadiene copolymer rubber; styrene / butadiene copolymer rubber, styrene / isoprene copolymer rubber, styrene / butadiene / isoprene terpolymer rubber; hydrogenated diene rubber; ethylene / propylene Ethylene / α-olefin copolymers such as copolymers, saturated polyolefin rubbers such as propylene / other α-olefin copolymers; ethylene / propylene /
Α-olefin / diene polymer rubber such as diene copolymer, α-olefin / diene copolymer, isobutylene / isoprene copolymer, isobutylene / diene copolymer; urethane rubber, silicone rubber, polyether rubber, Special rubbers such as acrylic rubber, propylene oxide rubber and ethylene acrylic rubber; thermoplastic elastomers such as styrene / butadiene / styrene block copolymer rubber and styrene / isoprene / styrene block copolymer rubber; hydrogenated thermoplastic elastomers; urethane-based A thermoplastic elastomer; a polyamide-based thermoplastic elastomer; and a 1,2-polybutadiene-based thermoplastic elastomer.

As other thermoplastic resins, for example,
Polyolefins such as low density polyethylene, high density polyethylene, linear low density polyethylene, ultra low density polyethylene, polypropylene, polybutene, polypentene;
Polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 6 and nylon 66; ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, polystyrene, syndiotactic polystyrene, polyphenylene sulfide, polyphenylene ether, polyamide, Examples include polyester and polycarbonate.

These other polymers can be used alone or in combination of two or more as required. The amount of the other polymer is usually 1 to 100 parts by weight of the cyclic olefin polymer.
It is at most 00 parts by weight, preferably at most 50 parts by weight. If the amount of the other polymer exceeds 100 parts by weight, the releasability is reduced, and the toner adheres.

The cyclic polyolefin used in the present invention can be mixed with a charge control agent to control its triboelectric charging characteristics. In particular, when a negatively charged toner is used, the addition of a positively charged control agent can reduce the triboelectric charging characteristics, particularly the amount of toner charge and the amount of reversely charged toner. This is because the cyclic polyolefin is originally located on the negative charge side in the triboelectric series. The triboelectric series of the material used with respect to the cyclic polyolefin can be easily known by frictionally charging both materials and measuring the charge polarity (and charge potential) of the cyclic polyolefin with a surface voltmeter.

For example, when the material used is a polymer,
A roller provided with a cyclic polyolefin on the surface is installed in a developing device represented by FIG. 4, and is rotated in sliding contact with a blade on which a material to be used is applied or affixed, and the charging polarity (potential) of the roller is measured. (At this time, other members such as the toner and the supply roller are not brought into sliding contact with the developing roller.) In the case of a powder or a liquid, it can be known by adding a material to the cyclic polyolefin used for the developing roller, installing the material on the blade surface, and measuring the charging polarity of the roller in the same manner as described above.

The compound which can be added can be used as long as it is located on the positive charging side in the triboelectric series relative to the cyclic polyolefin, but a so-called charge controlling agent used for controlling charging of the toner, carrier, developing roller and the like is preferable.

Specific examples of the compound include a nigrosine compound, a quaternary ammonium salt compound, a pyridinium salt compound, and triaminotriphenylmethane (JP-A 2-2).
No. 67565), metal salts of higher fatty acids, metal complexes of acetylacetone, and the like. Examples of high molecular weight compounds include polyamine resins (such as the resin described in JP-B-53-13284) and acrylic resins having a quaternary ammonium base. Resins (such as those described in JP-A-62-210472),
Examples include block polymers of a quaternary ammonium base-containing polymer and a lipophilic polymer (eg, resins described in US Pat. No. 4,925,764), specifically, “Bontron P-51” (trade name) manufactured by Orient Chemical Industries, "Bontron AFPB" (trade name), "TP" manufactured by Hodogaya Chemical Industry Co., Ltd.
-302 "(product name)," TP-415 "(product name),
"VP SN 4001" (trade name) manufactured by Bayer AG is exemplified.

The addition amount of these charge control agents is preferably 0.5 to 10 parts by weight based on 100 parts by weight of the polymer component mainly composed of a cyclic polyolefin. The amount added is 0.
If the amount is less than 5 parts by weight, no improvement in triboelectric charging characteristics can be expected.
If the amount exceeds 10 parts by weight, a problem that the releasability of the surface is reduced occurs.

The layer containing the surface mainly composed of the cyclic polyolefin of the present invention (the surface layer of the thin-layer roller composed of a material mainly composed of the cyclic polyolefin) controls the volume resistance by adding an appropriate conductive agent. be able to. As a result, by providing a potential difference between the thin layer roller and the developing roller, it becomes possible to electrically control the frictional charging characteristics of the toner, particularly the generation of the oppositely charged toner. In this case, by setting the potential of the thin layer roller to the negative side of the developing roller for negatively charged toner, and setting the potential of the oppositely charged toner in the toner layer to the positive side of the developing roller for positively charged toner. Is held by the electric field, and the amount of the oppositely charged toner in the toner thin layer on the developing roller after passing through the sliding contact portion with the thin layer roller can be reduced.

The volume resistance of the surface layer of the thin roller is 10 ¹² Ω.
・ Cm or less is preferable. When the volume resistance exceeds 10 ¹² Ω · cm, the effective electric field holding force of the oppositely charged toner rapidly decreases.

The volume resistance of the layer containing the surface mainly composed of the cyclic polyolefin of the present invention can be controlled by adding a general conductivity controlling agent.

Specific examples of the material include metal powders such as Ni and Cu; carbon blacks such as furnace black, lamp black, thermal black, acetylene black, and channel black; tin oxide, zinc oxide, molybdenum oxide, antimony oxide; Examples include conductive oxides such as potassium titanate; electroless plating products obtained by plating on titanium oxide and mica; inorganic fillers such as graphite, metal fibers, and carbon fibers; and surfactants.

The layer containing the surface mainly composed of the cyclic polyolefin of the present invention can be provided on the elastic layer. Due to the flexibility of the cyclic polyolefin, it can sufficiently follow the elastic layer and can be used stably without generation of cracks and cracks.

Specific materials that can be used for the elastic layer are shown below. Diene rubbers such as styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile-butadiene rubber (NBR), nitrile-isoprene rubber (NIR) and chloroprene rubber (CR); butyl rubber (II)
R), olefin rubbers such as ethylene-propylene rubber (EPM, EPDM) and chlorosulfonated polyethylene (CSM); ether rubbers such as epichlorohydrin rubber (CHR, CHC); other silicone rubbers, fluorine rubbers, acrylic rubbers, urethanes Rubber, furthermore styrene, olefin,
Elastomer materials such as thermoplastic elastomers such as polyvinyl chloride, urethane, polyester, polyamide, fluorine, and chlorinated polyethylene can be used.

These materials can be made conductive by adding a conductive agent. In this case, the above-described conductive agent can be used, but the resistance can also be reduced by blending a known low-resistance rubber material such as epichlorohydrin rubber or nitrile-butadiene rubber. Further, by setting the volume resistance of the elastic layer to 10 ¹² Ω · cm or less, the above-described electric field effect between the thin layer roller and the developing roller can be obtained.

[0049] The cyclic polyolefin used in the present invention may optionally contain a compounding agent. The compounding agent is not particularly limited as long as it is generally used in the resin industry, for example, an antioxidant,
UV absorbers, lubricants, anti-fog agents, anti-fog agents, plasticizers, pigments,
Near-infrared absorbing agents, antistatic agents and the like can be mentioned.
These compounding agents can be used alone or in combination of two or more. The amount of the other compounding agents is appropriately selected within a range that does not impair the purpose of the present invention.

In particular, the friction coefficient can be stably reduced by adding polyethylene wax. In general, waxes, especially polyethylene wax, have a large effect of reducing the surface friction coefficient, but the compatibility with general-purpose resins is poor and the concentration distribution is oriented in the thickness direction of the surface layer, and the friction coefficient increases rapidly when the outermost surface is worn. Had the disadvantage of doing so.

The cyclic polyethylene used in the present invention has a high affinity with the polyethylene wax in that respect and has a small concentration distribution in the thickness direction of the surface layer, so that the friction coefficient is stable with time.

The polyethylene wax is 500 to 1000
It is an ethylene polymer having a polar group of 0 and is generally classified into an emulsified type having a polar group and a non-emulsified type having no polar group, and any of them can be used in the present invention. These include Mitsui Petrochemical (High Wax), Sanyo Chemical (Sun Wax), Mitsubishi Chemical (Dialen), Hoechst (Hoechst Wax),
It is marketed and available from manufacturers such as BASF (A-Wax).

The amount of these polyethylene waxes to be added depends on the amount of the polymer component 100 mainly composed of cyclic polyolefin.
It is preferred to add 0.01 to 5 parts by weight based on parts by weight. If the amount is less than 0.01 part by weight, the effect of reducing the friction coefficient cannot be expected, but if it exceeds 5 parts by weight, a problem that the releasability of the surface is deteriorated occurs.

Next, a method for manufacturing the thin layer roller of the present invention will be described. As the thin-layer roller of the present invention, a roller formed by molding the above-mentioned components (including a cyclic olefin-based polymer and, if necessary, other polymers and compounding agents) is used.

The molding can be performed according to a conventional method, for example, a melt molding method or a method such as coating after dissolving in a solvent can be used. When a thin layer roller is formed by a melt molding method, there are a melt extrusion method such as an inflation method, a calender method, a hot press method, an injection molding method, and the like.

The conditions of the melt molding method are appropriately selected according to the molding method. For example, in the case of the melt molding method, the resin temperature is appropriately selected within a range from the glass transition temperature to the decomposition temperature. ~ 400 ° C, preferably 150 ~
The temperature is 350 ° C., more preferably 200 to 300 ° C., and the temperature of the take-off roll is usually 0 to 200 ° C., preferably 30 to 180 ° C., more preferably 50 to 150 ° C.

When a thin layer roller is prepared after dissolving in a solvent, it can be carried out according to a conventional method. For example, a liquid composition in which each component is dissolved or dispersed in a solvent is placed on a suitable carrier (support). It can be carried out by casting and then drying and removing the solvent.

The carrier is not particularly limited and those used in a general solution casting method can be used. Examples thereof include a metal roller such as SUS and Al, a conductive resin roller, and a rubber roller. .

Examples of the solvent include aromatic hydrocarbons such as benzene, toluene and xylene; alicyclic hydrocarbons such as cyclohexane; esters such as butyl acetate; ethers such as tetrahydrofuran and dimethoxyethane; Alcohols such as ethanol and isopropanol; ketones such as methyl ethyl ketone; halogenated solvents such as methylene chloride, chloroform, carbon tetrachloride, and ethylene dichloride;

These solvents can be used alone or in combination of two or more. The concentration of the cyclic olefin-based polymer in the solvent is appropriately selected according to the thickness of the film to be produced, but is usually 0.1 to 60% by weight, preferably 1 to 50% by weight, more preferably 5 to 4% by weight.
It is in the range of 5% by weight. When the concentration of the cyclic olefin-based polymer is in this range, the film thickness is easily adjusted and the film-forming properties are excellent, which is preferable.

The method for casting the liquid composition on the carrier is not particularly limited, and it can be carried out using, for example, a doctor knife, a Meyer bar, a roll coat, or the like. The liquid composition may be cast by spraying, brushing, rolling, spin coating, dipping, or the like. If the desired film thickness cannot be obtained by one coating, the coating can be repeated.

The structure of the thin-layer roller used in the developing device of the present invention may be such that at least the surface has a surface mainly composed of a cyclic polyolefin, and the structure of the lower layer may take various forms as necessary. be able to. In addition to providing the elastic layer as described above, it is also possible to provide an adhesive layer at the interface for improving the adhesiveness with the lower layer.

Next, the image forming apparatus of the present invention will be described in detail with reference to the drawings. The image forming apparatus of the present invention includes the above-described developing device, at least a charging device, an exposure device, a transfer device, a cleaning device, and a charge removing device, and includes an electrophotographic photosensitive member. I have.

FIG. 2 is a schematic diagram for explaining the image forming apparatus of the present invention, and the following modified examples also belong to the category of the present invention. In FIG. 2, the image forming apparatus includes a charge removing exposure unit (a charge removing lamp) that is close to the upper surface of the drum-shaped photosensitive member 1 and along the circumference in a counterclockwise direction.
2, charging charger 3, eraser 4, image exposure unit 5, developing device (developing unit) 6, pre-transfer charger 7, transfer charger 10, separation charger 11, separation claw 12, pre-cleaner charger 13, fur brush 14, cleaning brush 15 are sequentially attached. Further, a registration roller 8 for feeding the transfer paper 9 between the photoconductor 1 and the transfer charger 10 and the separation charger 11 is additionally provided. The photoreceptor 1 includes a drum-shaped conductive support and a photosensitive layer in close contact with the upper surface thereof, and rotates counterclockwise.

In the above image forming apparatus, the photosensitive member 1
Rotates counterclockwise, is charged negatively (or positively) by the charger 3, and forms an electrostatic latent image on the photoconductor 1 by exposure from the image exposure unit 5.

As the transfer means, the above-mentioned charger can be generally used. However, as shown in FIG. 2, a combination of a transfer charger and a separation charger is effective.

The light source used in the image exposure section 5, the neutralizing lamp 2, etc. includes a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (LD). EL) or the like can be used. And, in order to irradiate only the light in the desired wavelength range,
Various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can also be used. Such a light source or the like may be used when the photosensitive member is irradiated with light by providing a transfer step using light irradiation, a cleaning step, or a pre-exposure step in addition to the image exposure step and the charge removal step. Can be.

In the developing device 6, the electrostatic latent image is developed by attaching toner onto the photoreceptor 1, and the charged state of the toner image is adjusted by the pre-transfer charger 7, and then transferred onto the transfer paper 9 by the transfer charger 10. The toner image is transferred, the electrostatic adhesion between the photoconductor 1 and the transfer paper 9 is eliminated by the separation charger 11, and the transfer paper 9 is separated from the photoconductor 1 by the separation claw 12. After the transfer paper 9 is separated, the surface of the photoconductor 1 is cleaned by the pre-cleaning charger 13, fur brush 14 and cleaning brush 15. This cleaning can also be performed by removing the remaining toner with only the cleaning brush 15.

When a negative (or positive) charge is applied to the photoreceptor to perform image exposure, a negative (or positive) electrostatic latent image is formed on the photoreceptor. If this is developed with positively (or negatively) charged toner (electrostatic detection fine particles), a positive image can be obtained,
Conversely, a negative image can be obtained by developing with negatively (or positively) charged toner. A known method can be applied to such a developing unit, and a known method is also used for the charge removing unit.

Although the photosensitive member is shown as a drum in this example, a sheet or an endless belt may be used. Accordingly, the contact method (contact, non-contact) and type (elasticity) of the developing roller in the developing device can be appropriately selected, and the thin layer roller can also be selected accordingly as described above.

The image forming means of the present invention as described above may be fixed and incorporated in an apparatus such as a copying machine, a facsimile, a printer, or the like, but may be incorporated in the apparatus in the form of a process cartridge. Is also good. The process cartridge is one device (part) that includes a photoconductor and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge removing unit. There are many shapes and the like of the process cartridge. As a general example, the one shown in FIG.

The process cartridge shown in FIG.
Charger 17, Cleaning Brush 18, Image Exposure Unit 19, Developing Roller 2, Arranged around Photoconductor 16
0, a compact structure including a thin layer roller 21, a supply roller 22, and the like.

[0073]

Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted by such specific Examples.

Example 1 100 parts by weight of a cyclic polyolefin (manufactured by Mitsui Petrochemical Co., Ltd., trade name: Apel APL6509, glass transition point: 80 ° C.) was dissolved in 500 parts by weight of toluene, and the solution was applied to a SUS roller (12φ). Spray applied. This was dried at 120 ° C. for 1 hour to obtain a thin roller having a thickness of 20 μm.

This thin-layer roller was mounted on the developing device shown in FIG. 1, and idled for 100 hours under the following conditions. The toner charge amount (q / m) before and after idling, the amount of adhesion (m / a) and the surface toner after idling are removed by air blow, and the adhesion state of toner aggregates and toner filming property are evaluated by the following evaluation methods. evaluated. Table 1 shows the results.

(Developing Apparatus) Developing roller: 6φ, linear speed 100 mm / s Evicle hydrin rubber 4 mm elastic layer / silicone resin surface layer Supply roller: 12φ, linear speed 120 mm / s Conductive urethane sponge Thin layer roller: 12φ, Linear speed 20 mm / s Bias: Each roller is grounded, 0 V Toner: Cyan toner type 5100 (manufactured by Ricoh)

(Evaluation method) Toner charge amount, adhesion amount: blow-off method Aggregate adhesion state: surface visual observation and microscope (manufactured by Keyence Corporation) Toner filming property: ΔID defined by the following equation
(Toner filming). ΔID (toner filming) = ID (after idling) −ID (R
ef) ID (after idling), ID (Ref): Tape transfer of thin roller surface after air blow, Ricoh paper type 6
000 and measure ID with Macbeth densitometer. ID
(Ref) measures the ID of the untransferred tape in the same way. Tolerable range: ΔID (toner filming) is 0.05 or less as an allowable range.

Example 2 In Example 1, the cyclic polyolefin was replaced with Apel APL6011 manufactured by Mitsui Petrochemical Co., Ltd.
(Trade name: glass transition point: 105 ° C.) Except for changing to a glass transition point, a thin layer roller was manufactured and evaluated in the same manner as in Example 1.
Table 1 shows the results.

[Comparative Example 1] A spray coating was carried out in the same manner as in Example 1 except that PTFE (polytetrafluoroethylene) paint (manufactured by Daikin Industries, Ltd., trade name: EK4100) was used without using a cyclic polyolefin. C. for 1 hour to obtain a thin layer roller having a thickness of 15 .mu.m. This thin layer roller was evaluated in the same manner as in the example. Table 1 shows the results.

Comparative Example 2 Instead of the PTFE coating of Comparative Example 1, 100 parts by weight of a solvent-soluble fluororesin (trade name: Lumiflon 600, manufactured by Asahi Glass Co., Ltd.) was added to an isocyanate curing agent (trade name: Lumiflon 600, manufactured by Asahi Glass Co., Ltd.) Curing agent) 3
0 parts by weight, 300 parts by weight of xylene, and 150 parts by weight of methyl isobutyl ketone were added and spray-coated in the same manner, followed by curing at 150 ° C. for 30 minutes to obtain a thin layer roller having a film thickness of 20 μm. This thin layer roller was evaluated in the same manner as in the example.
Table 1 shows the results.

[0081]

[Table 1]

The fluorinated resin of Comparative Example 1 had a low toner charge amount and caused thin layer unevenness, and the aging characteristics could not be evaluated.

[Examples 3 to 6] After the cyclic polyolefin used in Example 1 was similarly dissolved in toluene, 5 parts by weight of a positive charge control agent shown in Table 2 was added to 100 parts by weight of the cyclic polyolefin. Ball mill dispersion was performed for 72 hours.
A thin roller was manufactured in the same manner as in Example 1. This was mounted on the developing device used in Example 1, and the toner charge amount and adhesion amount were measured. Next, ΔID (reversely charged toner) was evaluated by the following method. Table 2 shows the results.

(Method of Evaluating ΔID (Reversely Charged Toner)) FIG.
Was brought into contact with the belt OPC photoconductor, and development was performed under the conditions corresponding to the following image background, and the ΔID of the toner on the OPC was measured.

(Developing conditions) Potential of each member: development, supply, thin layer each roller + 400v,
Belt OPC 0v Linear velocity of each member: Belt OPC 66.6 mm / s, each roller is the same as in Example 1, ΔID (reversely charged toner) = ID (OPC
Upper toner) -ID (Ref) Allowable range: ΔID (reversely charged toner) is 0.05 or less as an allowable range.

[0086]

[Table 2]

[Examples 7 to 9] 100 parts by weight of toluene-dissolved cyclic polyolefin used in Example 1 (in terms of solid content)
Carbon black (Cabot, BP-
L) 40 parts by weight were added, and ball mill dispersion was performed for 72 hours to prepare a carbon master batch for resistance control.

Using this master batch, a coating material having the amount of carbon shown in Table 3 was prepared and spray-coated in the same manner as in Example 1 to obtain a thin-layer roller having surface layers having different volume resistances. These thin-layer rollers were mounted on the developing device shown in FIG. 1 and ΔID (reversely charged background stain) was measured by the same method as in Examples 3 to 6 under the following potential conditions. Table 3 shows the results. Potential of each member: development, supply, each roller + 400v, thin layer roller + 200v, belt OPC 0v

[0089]

[Table 3]

[Embodiments 10 and 11] As an elastic layer, epichlorohydrin rubber (Epichromer CG manufactured by Daiso Co., Ltd., rubber hardness JISA50) used for the developing roller in Embodiment 3 was used.
Degree, layer thickness 2 mm) (Example 10), and the surface layer used in Example 8 was spray-coated on carbon black-added conductive silicone rubber (rubber hardness JISA 60 degrees, layer thickness 2 mm) (Example 11). A thin layer roller was prepared. This was mounted on the developing device shown in FIG. 1, and after a continuous idle operation for 100 hours in the same manner as in Example 1, the surface was subjected to a microscope (Keyence VH5900).
Was observed at a magnification of 200 times, but no adhesion of toner aggregates and no filming were observed.

[Examples 12 to 14] 0.3 parts by weight of polyethylene wax (manufactured by Mitsui Petrochemical) was added to 100 parts by weight (in terms of solid content) of the toluene-dissolved cyclic polyolefin of Example 1, and the mixture was dispersed in a ball mill for 72 hours. went. Thereafter, a thin-layer roller was manufactured in exactly the same manner as in Example 1.

The surface friction coefficient was calculated from the following equation by the Euler belt method. Table 4 shows the results. μs = 2 / π × 1n (F / w) μs: coefficient of static friction, F: measured value, w: load (100
g) μs is preferably between 0.20 and 0.55. 0.
If it is 55 or more, the torque with a contact member such as a developing roller or a scraper increases, and jitter or the like is easily generated. 0.
If it is less than 20, the slipperiness becomes too high, and it becomes difficult to regulate the toner thin layer, which hinders the uniformity of the thin layer.

[0093]

[Table 4]

[Embodiment 15] The developing device using the thin layer roller used in Embodiment 8 was attached to the image forming apparatus shown in FIG. )
When the surface of the thin roller after printing was observed under magnification in the same manner as in Examples 10 and 11, the image (stain on the background) was good, there was no adhesion of toner aggregates on the surface of the thin roller, and no filming occurred.

[0095]

According to the present invention, at least the surface of the thin layer roller is made of a material mainly composed of a cyclic polyolefin, so that adhesion of toner aggregates and toner filming on the surface of the thin layer roller are prevented, A stable toner thin layer can be obtained.

Further, according to the developing device of the present invention, the toner charging characteristics are improved, especially the amount of the oppositely charged toner is reduced, and the image forming apparatus equipped with the developing device of the present invention has little background contamination, This can provide a high-quality image in which the occurrence of the image is prevented. Further, a developing device that can cope with various developing methods such as contact and non-contact can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a developing device having a thin layer roller according to the present invention.

FIG. 2 is a schematic diagram illustrating an image forming apparatus according to the present invention.

FIG. 3 is a schematic view showing an example of a structure when the image forming apparatus according to the present invention is in the form of a process cartridge.

FIG. 4 is a schematic diagram for explaining a developing device having a developing blade.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 2 static elimination lamp 3 charging charger 4 eraser 5 image exposure unit 6 developing unit 7 pre-transfer charger 8 registration roller 9 transfer paper 10 transfer charger 11 separation charger 12 separation claw 13 pre-cleaning charger 14 fur brush 15 cleaning brush 16 photoconductor 17 Charger 18 Cleaning Brush 19 Image Exposure Unit 20 Developing Roller 21 Thin Roller 22 Supply Roller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 65/00 C08L 65/00 F16C 13/00 F16C 13/00 EF Term (Reference) 2H077 AC02 AC04 AD06 AD14 AD14 AD23 AE04 EA14 EA15 FA13 FA22 FA26 GA03 3J103 AA02 AA51 BA41 BA43 FA07 FA14 FA18 GA02 GA52 GA57 GA58 GA60 HA03 HA04 HA05 HA12 HA33 HA37 HA41 HA53 HA54 4J002 BB03X BK00W CE00W FD17X GS00

Claims (6)

[Claims] A developing roller that is disposed opposite to an image carrier that carries an electrostatic latent image and supplies toner to the electrostatic latent image; A toner supply roller for performing triboelectric charging,
A thin roller that regulates the toner thin layer formed around the toner carrier to a uniform layer thickness, wherein at least the surface of the thin layer roller is made of a material mainly composed of a cyclic polyolefin. A developing device comprising: 2. The developing apparatus according to claim 1, wherein the material mainly composed of the cyclic polyolefin contains a compound whose triboelectric series is located on the positively charged side of the cyclic polyolefin. 3. The volume resistance of the surface layer of the thin roller is:
The developing device according to claim 1, wherein the developing device has a resistivity of 10 ¹² Ω · cm or less. 4. The developing device according to claim 1, wherein said developing roller has an elastic layer. 5. The method according to claim 1, wherein the material mainly composed of the cyclic polyolefin contains a polyethylene wax.
The developing device according to any one of the above. 6. A device comprising: the developing device according to claim 1; a charging device; an exposing device; a transfer device; a cleaning device; a charge removing device; and an electrophotographic photosensitive member. An image forming apparatus comprising: