JPH11327284A - Developing roller - Google Patents

Abstract

(57) [Problem] To reduce the radial thickness of a conductive elastic layer by using means other than increasing the diameter of a conductive shaft, and to obtain temperature and humidity while having a conductive elastic layer. It is an object of the present invention to provide a developing roller capable of always maintaining the positional relationship between the photosensitive member and the regulating blade within a certain range without being affected by environmental changes such as the above. SOLUTION: The conductive elastic layer 2 and the conductive elastic layer 2 are provided.
And a non-conductive resin layer 3 supporting the conductive elastic layer 2. The conductive elastic layer 2 has an inner peripheral surface in contact with a conductive coating layer 4 provided on an outer peripheral surface 3 a of the non-conductive resin layer 3, and has a coating. It is characterized by being electrically coupled to an external power supply through the layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing roller mounted on a developing device used in an electrophotographic copying machine or printer, and more particularly to a developing roller employed in a developing system using a non-magnetic one-component developer. About.

[0002]

2. Description of the Related Art Various types of developing devices have been proposed for use in the above-described electrophotographic copying machines and printers. For example, a magnetic developer adsorbed by a magnetic roller is transferred to a photosensitive member. I have. However, in the method of supplying the magnetic developer using such a magnetic roller, not only is the magnetic roller expensive, but also the adjustment of the gap between the magnetic roller and the photoconductor is delicate, often in units of 0.1 mm. And the mechanism for satisfying the accuracy is complicated. In particular, when a magnetic two-component developer is used, the carrier itself has a life,
The replacement operation is troublesome and troublesome. Further, since a magnetic material having a different color is internally added to the magnetic developer itself, it has been technically difficult to convert the magnetic developer into a color toner.

[0003] In order to solve such inconveniences, several developing methods using a non-magnetic developer have been proposed.
For example, a developing method has been proposed in which a non-magnetic developer (hereinafter, simply referred to as “developer”) is conveyed using an electric attraction force. In this developing method, the developer is frictionally charged between a regulating blade that regulates the thickness of the developer deposited on the surface of the developing roller and the surface of the developing roller, so that the developer is prevented from cracking due to the pressure of the regulating blade. It has been studied to use a developing roller in which a flexible conductive elastic layer is coated on a conductive shaft so that the conductive elastic layer may be exposed as it is on the surface of the developing roller. In many cases, a thin surface protective layer is provided on the surface for the purpose of controlling charging and transportability of the toner.

However, since many materials used for the conductive elastic layer have a large linear expansion coefficient, the outer diameter of the developing roller changes to a non-negligible level depending on the environment. When the outer diameter of the developing roller greatly changes, for example, the contact width between the developing roller and the photoconductor changes, or in the case of the non-contact developing method in which the developing roller does not contact the photoconductor,
The distance between the photoreceptor and the developing roller changes, making the transportability and charging characteristics of the developer on the surface of the developing roller unstable, and consequently, the image quality including the developing density is significantly reduced.
For example, even if a good image is obtained in a 20 ° C. and 60% RH environment, a good image may not be obtained in a 35 ° C. and 85% RH environment.

Therefore, a method of reducing the outer diameter fluctuation of the developing roller by reducing the thickness of the conductive elastic layer has been considered. In this case, the core supporting the thinned elastic layer has a large diameter. I do. Generally, a metal shaft is used for the core body because conductivity for applying a voltage to the conductive elastic layer and sufficient bending rigidity for supporting the developing roller without bending are required. When the diameter of the metal shaft is increased as described above, the weight of the developing roller, the developing device, and the copier or the printer is increased. Further, the weight of the developing roller increases the moment of inertia of the developing roller, and it is necessary to use a driving motor having a large driving torque. Furthermore, the end of the core portion supporting the conductive elastic layer is actually connected to a drive motor by a gear or the like, and the diameter is reduced. In order to reduce the diameter of the shaft, a large number of man-hours are involved in the cutting process in manufacturing, and the shaft becomes expensive when the machining cost and the material cost are included.

The present invention has been made in view of the above situation, and the thickness of the conductive elastic layer in the radial direction (hereinafter referred to as "elastic layer thickness") is determined by using means other than increasing the diameter of the metal shaft. To provide a developing roller that is small and has a conductive elastic layer, but can always maintain the positional relationship between the photoconductor and the regulating blade within a certain range without being affected by environmental changes such as temperature and humidity. Things.

[0007]

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, instead of increasing the diameter of the metal shaft, a resin having a small linear expansion coefficient, particularly a lightweight and inexpensive resin, has been proposed. The present inventors have found that the thickness of the elastic layer can be reduced while avoiding the above-mentioned problems by using a non-conductive resin to increase the diameter of the core body, thereby completing the present invention.

That is, the present invention relates to a developing roller for use in a developing device employing a non-magnetic one-component system, comprising a conductive elastic layer and a non-conductive resin layer supporting the conductive elastic layer. The conductive elastic body layer has an inner peripheral surface in contact with a conductive coating layer provided on an outer peripheral surface of the non-conductive resin layer, and is electrically coupled to an external power supply through the coating layer. An object of the present invention is to provide a developing roller. In such a developing roller, the non-conductive resin layer has a smaller linear expansion coefficient than the conductive elastic layer. Is small, the change in the outer diameter of the developing roller due to environmental changes such as temperature and humidity can be suppressed, and the contact width or interval (gap) between the developing roller and the thin film forming blade and the photoreceptor can be maintained within a certain range. Image can be obtained. Further, since the conductive elastic layer is electrically coupled to an external power supply by a conductive coating layer provided on the outer peripheral surface of the non-conductive resin layer, without increasing the diameter of the metal shaft, In addition, a lightweight and inexpensive non-conductive resin can be used for the resin layer supporting the conductive elastic layer, so that the material cost is greatly reduced, and this does not contradict the demand for a lightweight and compact developing roller.

Here, when the conductive coating layer is uniformly covered over the outer peripheral surface of the non-conductive resin layer in the longitudinal direction, the resistance value of the entire roller becomes substantially uniform, and the The transportability and charging characteristics of the developer are stabilized, and good image quality is maintained.

When a conductive shaft is insert-molded in the non-conductive resin layer, the conductive coating layer and the conductive shaft are electrically coupled to each other to form a conductive elastic layer. It is electrically coupled to an external power supply.

In addition, a roller support made of the same material as the non-conductive resin layer is integrally formed at both ends of the non-conductive resin layer,
The need for a conductive shaft is eliminated, and the weight, size, and cost of the developing device are promoted.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will now be described with reference to the illustrated embodiments. As shown in FIGS. 1 to 3, the developing roller employing the non-magnetic one-component system mainly includes a conductive elastic layer 2, a non-conductive resin layer 3 supporting the conductive elastic layer 2, and a non-conductive resin. In the present embodiment, a surface protection layer 5 having a thickness of 10 to 150 μm is provided on the conductive elastic layer 2. The surface protection layer 5 has a thickness of 10 to 150 μm. In the first and second embodiments shown in FIGS. 1 and 2, the shaft is provided with a conductive shaft 6 made of a metal shaft made of SUS or aluminum and having a diameter of about 1 to 12 mm. The developing roller 1 of the present invention is provided with the inexpensive and lightweight non-conductive resin layer 3 and the coating layer 4.
It is necessary to reduce the radial thickness of the conductive elastic layer 2 without increasing the diameter of the conductive shaft body 6 and to maintain electrical coupling between the conductive elastic layer 2 and an external power supply. Features.

The core portion of the developing roller has a function of applying a voltage to the conductive elastic layer, a bending rigidity capable of supporting the developing roller without bending, and a small dimensional change with respect to environmental changes such as temperature and humidity. However, the function of the conductive coating layer 4 is the function of the conductive shaft 6.
However, the function is mainly performed by the non-conductive resin layer 3 and the conductive shaft 6. For the non-conductive resin layer 3, a known thermosetting resin or thermoplastic resin is used, and in particular, polyester,
It is preferable to use a synthetic resin such as polyamide, polyethylene, and polycarbonate that has little dimensional change due to the environment.

As shown in FIG. 1 as a first embodiment, such a developing roller 1 has a conductive shaft 6 disposed on a shaft portion, and an outer peripheral surface 3a and both end surfaces 3b on the conductive shaft 6. 3b ', a non-conductive resin layer 3 having a coating layer 4 provided thereon, and a conductive elastic layer 2 whose inner peripheral surface is in contact with the coating layer 4 are sequentially laminated concentrically on the non-conductive resin layer 3. The conductive elastic layer 2 is electrically coupled to the conductive shaft 6 via the coating layer 4. The provision of the coating layer 4 makes it possible to apply a voltage to the conductive elastic layer 2. In this embodiment, the coating layer 4 is uniformly coated on the outer peripheral surface 3a in the axial direction. As a result, the resistance value of the entire roller and the potential on the surface of the developing roller 1 become uniform, so that the transportability and charging characteristics of the developer on the surface of the developing roller 1 are stabilized, and good image density and image quality can be obtained. it can.
Incidentally, the developing roller 1 of the present embodiment has the both end faces 3b, 3b '.
The coating layer 4 is provided uniformly on the entire surface, but it is sufficient that the coating layer 4 on both end faces 3b, 3b 'can electrically couple the conductive elastic layer 2 and the conductive shaft 6. However, the coating form is not limited to this embodiment.

As a second embodiment, as shown in FIG.
It is also preferable that the roller supporting portions 7 and 7 ′ have a stepped shape by the non-conductive resin layer 3 and the coating layer 4. According to this, by forming or processing the non-conductive resin layer 3 and the coating layer 4 without processing the conductive shaft body 6, the roller supporting portion engaging with the driving portion can be formed into a relatively free shape. And it can be easily manufactured. Further, by limiting the material used for the non-conductive resin layer 3 to a material having a large elastic coefficient and increasing the bending rigidity of the non-conductive resin layer itself, the diameter of the conductive shaft body can be reduced, or the third embodiment can be used. As shown in FIG. 3, the roller support portions 7 and 7 'can be integrally formed with the non-conductive resin 3 without using the conductive shaft, so that the weight and cost can be reduced. In the case of the present embodiment, the coating layer 4 is formed of the nonconductive resin layer 3
By providing them on the surfaces of the roller support portions 7, 7 ', the conductive elastic layer 2 and an external power supply can be electrically coupled.

The conductive material constituting the conductive coating layer 4 is a metal plating, a conductive paint, a conductive adhesive, a conductive resin, or the like.
Electro-composite plating, metal spraying, vacuum deposition, low-temperature sputtering, ion plating, roll coater, spray coating, etc., or processing the conductive material into a sheet and winding it around a large-diameter resin of the support, etc. Is coated on the conductive resin layer.

Since the conductive elastic layer 2 is elastically deformed by the pressure of the thin film forming blade or the photoreceptor, cracking of the developer by the thin film forming blade can be prevented, and in the contact type developing device, the conductive elastic layer 2 is located between the photoreceptor. 0.5-2m
It has a function of securing a contact width of about m, that is, a nip width.

The material of the conductive elastic layer 2 is NBR.
(Nitrile butadiene rubber), EPDM, silicon,
Urethane and the like, and their foaming materials are used, and there is no particular limitation. However, a reaction product of the curable composition described below is preferable. Since these have a particularly flexible structure, even if the conductive elastic layer is made thin, a sufficient elastic effect can be exhibited. In addition, when containing an oxyalkylene unit, it is easy to handle because it has a low viscosity before curing, and when it contains a saturated hydrocarbon unit, it has a low water absorption and little change in volume and roller resistance even in a high humidity environment. It is preferred in that respect.

That is, (A) a polymer having at least one alkenyl group in the molecule, wherein the repeating unit constituting the main chain is mainly composed of an oxyalkylene unit or a saturated hydrocarbon unit; It is preferable to use a reaction cured product of a curable composition containing a curing agent having at least two hydrosilyl groups therein and (C) a hydrosilylation catalyst as main components.

The polymer of the component (A) in the curable composition is a component which is cured by a hydrosilylation reaction with the component (B), and has at least one alkenyl group in the molecule. It occurs and becomes polymer and hardens. The number of alkenyl groups contained in the component (A) is required to be at least one from the viewpoint of hydrosilylation reaction with the component (B), but from the viewpoint of rubber elasticity,
In the case of a linear molecule, two alkenyl groups are present at both ends of the molecule. In the case of a branched molecule, two alkenyl groups are present at the molecular terminal.
Preferably, there are at least two alkenyl groups.
The main repeating unit constituting the main chain of the component (A) is an oxyalkylene unit or a saturated hydrocarbon unit.

In the case of a polymer in which the main repeating unit constituting the main chain is an oxyalkylene unit, the volume resistance is 10 ⁸ Ωcm to 10 ⁹ just by adding a small amount of a conductivity-imparting agent.
Ωcm is preferable. Further, from the viewpoint of lowering the hardness of the cured product, an oxyalkylene-based polymer in which the repeating unit is an oxyalkylene unit, and more preferably an oxypropylene-based polymer in which the repeating unit is an oxypropylene unit.

Here, the oxyalkylene-based polymer is a polymer in which 30% or more, preferably 50% or more, of the units constituting the main chain are composed of oxyalkylene units. Examples of the unit include compounds derived from compounds having two or more active hydrogens, such as ethylene glycol, bisphenol compounds, glycerin, trimethylolpropane, and pentaerythritol, which are used as starting materials in the production of polymers. . In the case of an oxypropylene-based polymer, a copolymer (including a graft copolymer) with a unit composed of ethylene oxide, butylene oxide, or the like may be used.

The hydrosilylation catalyst as the component (C) is not particularly limited as long as it can be used as a hydrosilylation catalyst. Platinum simple substance, solid platinum supported on simple substance such as alumina, chloroplatinic acid (including complex such as alcohol), various complexes of platinum, chloride of metal such as rhodium, ruthenium, iron, aluminum, titanium, etc. No. Among these, chloroplatinic acid, a platinum-olefin complex, and a platinum-vinylsiloxane complex are preferable from the viewpoint of catalytic activity. These catalysts may be used alone or in combination of two or more.

The proportion of the components (A) and (B) used in the curable composition as described above is such that the amount of the hydrosilyl group in the component (B) is 0.2 per mole of the alkenyl group in the component (A). -5.0 mol, more preferably 0.4-2.5 mol, from the viewpoint of rubber elasticity.

The amount of component (C) used is as follows:
(A) 10 ^-1 to 1 based on 1 mol of the alkenyl group in the component.
0 ^-8 mol, more preferably 10 ^-1 to 10 ^-6 mol, especially 10 ^-3 mol
By using it in the range of from 10 to ⁶ mol, it is possible to make the reaction more efficient.

Further, a conductivity-imparting agent is added to the above-mentioned curable composition to obtain a conductive composition. Examples of the conductivity-imparting agent include carbon black, metal fine powder, organic compounds or polymers having a quaternary ammonium salt group, a carboxylic acid group, a sulfonic acid group, a sulfate group, a phosphate group, and the like. Ester amide,
Or ether imide polymer, ethylene oxide
Examples of the compound include a compound having a conductive unit represented by an epihalohydrin copolymer and methoxypolyethylene glycol acrylate, and a compound capable of imparting conductivity, such as an antistatic agent such as a polymer compound. These conductivity imparting agents may be used alone or in combination of two or more.

The amount of the conductive agent to be added is (A)
It is preferable that the content is not more than 30% by weight based on the total amount of the component (C) from the viewpoint of not increasing the rubber hardness. On the other hand, from the viewpoint of obtaining uniform resistance, the content is preferably 10% by weight or more, and the required rubber hardness and the volume resistivity of the cured product are 10 ³ to 10 ¹⁰ Ωc.
The addition amount may be determined from the balance of physical properties so as to obtain m.

Further, in addition to the components (A) to (C) and the conductivity-imparting agent, a storage stability improving agent such as a compound having an aliphatic unsaturated bond,
Organic phosphorus compounds, organic sulfur compounds, nitrogen-containing compounds,
You may add a tin compound, an organic peroxide, etc.

The curable composition may contain a filler, a storage stabilizer, a plasticizer, an ultraviolet absorber, a lubricant, a pigment, and the like for improving processability and cost.

Next, the material of the surface protective layer 5 covering the conductive elastic layer 2 will be described. The surface protective layer 5 is not particularly limited, but is preferably, for example, a nylon-based or polyurethane-based one from the viewpoint of favorably negatively charging the developer, and is preferably a fluorine-based rubber from the viewpoint of favorably positively charging the developer. .

The method of coating the surface protective layer 5 is not particularly limited, but typically includes a method of coating a tube by heat shrinkage, and a method of applying and drying the surface layer solution by a DIP, spray, roll coater or the like according to the viscosity. Coating method.

[0032]

According to the developing roller of the present invention as described above, the diameter of the core is increased by using a non-conductive resin layer having a smaller linear expansion coefficient than the conductive elastic layer. The thickness of the conductive elastic layer can be made as small as possible. When the thickness of the elastic layer is reduced in this manner, a change in the outer diameter of the developing roller due to environmental changes such as temperature and humidity is suppressed, and the contact width or gap (gap) between the developing roller and the thin film forming blade and the photoconductor is kept within a certain range. , And a good image can always be obtained. Further, since the conductive elastic layer is electrically coupled to an external power supply by a conductive coating layer provided on the outer peripheral surface of the non-conductive resin layer, the diameter of the conductive shaft is not increased. In addition, a lightweight and inexpensive non-conductive resin can be used for the resin layer supporting the conductive elastic layer, and the material cost can be greatly reduced.
The size can be reduced.

Here, if the conductive coating layer is uniformly covered over the outer peripheral surface of the non-conductive resin layer in the longitudinal direction, the resistance value of the entire roller becomes substantially uniform, and the The transportability and charging characteristics of the developer are stable, and good image quality can be maintained.

When a conductive shaft is insert-molded on the non-conductive resin layer, the conductive coating layer and the conductive shaft are electrically coupled to each other to form a conductive elastic layer. An external power supply can be electrically coupled.

In addition, since a roller supporting portion made of the same material as the non-conductive resin layer is integrally formed at both ends of the non-conductive resin layer, a conductive shaft is not required, and the developing device can be reduced in weight, size and weight. Cost reduction can be promoted.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a first embodiment of a developing roller of the present invention.

FIG. 2 is an explanatory view showing a second embodiment.

FIG. 3 is an explanatory view showing a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developing roller 2 Conductive elastic layer 3 Non-conductive resin layer 3a Outer peripheral surface 3b, 3b 'End surface 4 Coating layer 5 Surface protective layer 6 Conductive shaft 7, 7' Roller support

Claims (4)

[Claims] 1. A developing roller for use in a developing device employing a non-magnetic one-component system, comprising: a conductive elastic layer; and a non-conductive resin layer supporting the conductive elastic layer. A developing roller, wherein the elastic layer has an inner peripheral surface in contact with a conductive coating layer provided on an outer peripheral surface of the non-conductive resin layer, and is electrically coupled to an external power supply through the coating layer. 2. The developing roller according to claim 1, wherein the conductive coating portion is uniformly covered over the outer peripheral surface of the non-conductive resin layer in the longitudinal direction. 3. The developing roller according to claim 1, wherein the conductive coating portion is electrically connected to a conductive shaft body insert-molded in the non-conductive resin layer. 4. A roller support made of the same material as the non-conductive resin layer is integrally formed at both ends of the non-conductive resin layer.
Or the developing roller according to 2.