JPH0364781A - Developing device - Google Patents

Abstract

PURPOSE:To improve the electrostatic chargeability and release property of a toner and to prevent the generation of after-images at the time of long-term repetitive use by using conductive particles which are more negative in electrostatic chargeability than a resin constituting an electrode layer when a positive charge toner is used and using the conductive particles which are more positive in electrostatic chargeability than the above-mentioned resin when a negative charge toner is used. CONSTITUTION:A developing roller 5 has the electrode layer 21 contg. at least the resin and the conductive particles 23 in the outermost layer. The conductive particles 23 are made more negative in electrostatic chargeability than the resin constituting the layer 21 when the positive charge toner 2 is used. The particles are made more positive in electrostatic chargeability than the resin constituting the layer 21 when the negative charge toner 2 is used. For example, metallic particles of Ni, Cu, etc., having the higher negative electrostatic chargeability than fluoroplastic are used as the conductive particles 23 when the positive charge toner is used as the toner if the constituting resin of the electrode layer 21 is the fluoroplastic. Metallic particles of Al, Zn, Fe, etc., having the higher positive electrostatic chargeability than the fluoroplastic is used when the negative charge toner is used as the toner. The electrostatic chargeability and release property of the toner are improved and the generation of the after-images at the time of long-term repetitive use is prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a one-component toner developing device.

[Conventional technology]

Conventionally, as a method for developing an electrostatic latent image using a non-magnetic component toner, the toner on a toner carrier (i.e., a developing roller) is made into a thin layer using a blade-like or roll-like member, and this is used to form an electrostatic latent image. A method is known in which development is performed by contacting a photoreceptor on which a photoreceptor is formed. In this method, the developing roller repeats the following cycles: ■ Replenishing toner ■ Charging the toner ■ Forming a thin layer of toner ■ Transporting the toner ■ Developing ■ Eliminating residual charges. When the developing roller enters the cycle, a counter charge occurs due to frictional charging with the toner, and the distributed charge from the photoreceptor remains on its surface or inside, so the charging characteristics and development characteristics of the toner deteriorate with repeated use. However, there was a problem that so-called afterimage development occurred.

For this reason, various methods of neutralizing the developing roller have been studied, and for example, a method has been proposed in which a low-resistance member such as a metal brush or a conductive sponge is brought into contact with the surface of the toner carrier.

However, the method using a metal brush may cause streaks to appear on the image due to uneven contact with the surface of the toner carrier, and the method using a conductive sponge eliminates the afterimage. The effect was not sufficient. Furthermore, since these methods contact the toner carrier through a thin toner layer, they have the disadvantage that the static elimination effect is extremely poor. Also, to improve the static elimination effect.

Various attempts have been made, such as considering the material and density of the brush and the number of sponge rolls installed, but none have been able to completely eliminate the afterimage. On the other hand, as a result of these improvements on the developing system side, developing rollers that are very easy to initialize, in other words, no charge remains, have been developed.

For such a developing roller, for example, an elastic material having a medium volume resistivity (hereinafter referred to as "medium resistance") of 10 to 1011 Ω is used as the conductive substrate of the first coating layer, and a second coating layer is formed on the elastic material. There is a developing roller coated with a semiconductive material made of flexible synthetic resin and conductive particles. However, since the materials used for this product are NBR (tolyl butadiene rubber), ECO (epichlorohydrin rubber), chloroprene rubber, urethane rubber, etc., it is difficult to make a uniform and stable product, especially in terms of electrical properties. Environmental (
It has the disadvantage that the developing characteristics change depending on the environmental conditions.

On the other hand, a developing roller has been proposed in which a conductive elastic body having a volume resistivity of 10 6 Ω·value or less is used, a resin or rubber layer having a medium resistance to high resistance is laminated thereon, and then an electrode layer is sequentially laminated thereon. This product has the advantage that environmental resistance can be significantly improved by using resin or rubber (eg, silicone type, fluorine type polymer) with excellent heat resistance and moisture resistance in each layer.

However, this developing roller has medium to medium resistance as a coating layer.
Since a high-resistance resin is used, residual charges generated by the frictional charging process with the toner accumulate, which greatly affects the toner charging performance and development characteristics in the primary process, resulting in an afterimage. In addition, attempts have been made to promote charge leakage by dispersing conductive particles in the electrode layer of the developing roller to lower the resistance. Decreased charge amount and toner transportability ■ Excessive concentration and decreased resolution due to increased electric field strength with the holder due to lower resistance of the surface layer ■ Toner releasability of the surface layer due to the addition of a large amount of conductive particles There are problems such as a decrease in wear resistance, occurrence of toner filming, and a decrease in wear resistance, and the current situation is that no developing device that is satisfactory in all aspects has been developed.

[Problem to be solved by the invention]

The present invention has been made in view of the above-mentioned state of the prior art, and has excellent toner chargeability and mold releasability, does not produce afterimages even after repeated use over a long period of time, and has excellent durability and low cost. An object of the present invention is to provide a developing device that can be reduced in size and cost.

[Means to solve the problem]

According to the present invention, the above problem is solved by supplying toner by a replenishment roller onto a developing roller carrying toner on its surface, and forming a uniform thin layer on the developing roller by a regulating member, thereby preventing an electrostatic latent image. In a developing device that performs development, the developing roller has an electrode layer containing at least a resin and conductive particles as an outermost layer, and when positively charged toner is used, the conductive particles have a higher density than the resin constituting the layer. It is distantly related to the developing device, which is characterized in that it has a negative chargeability, and when a negatively charged toner is used, its chargeability is more positive than that of the resin constituting the layer.

The developing device of the present invention will be explained with reference to FIG.

In FIG. 1, 1 is a container, 2 is a toner, 3 is an agitator, 4 is a supply roller, 5 is a developing roller, 6 is a toner thin layer blade, and 7 is a photoreceptor.

In FIG. 1, a toner container 1 contains a non-magnetic monocomponent toner 2. As shown in FIG. This toner 2 is conveyed by an agitator 3 to a toner storage section formed by a replenishment roller 4 and a developing roller 5, and is supported on the surface of the developing roller 5. Furthermore, a uniform thin layer is formed by the toner thin layer blade 6, and the toner is triboelectrically charged to a predetermined polarity. The thin layer of toner is transported to the development area where the photoreceptor 7 holding the electrostatic latent image and the developing roller 5 are in contact, where the toner is electrostatically transferred from the developing roller to the photoreceptor 7 and the latent image is developed. In the process of 0 or more images being formed, the toner 2 and the developing roller 5 are electrostatically bonded by frictional charging, but after the toner 2 moves to the photoreceptor 7, there are
A counter charge remains, causing so-called afterimage development.

The developing device of the present invention is characterized by using a developing roller having a specific structure as described above in order to quickly leak such counter charge and improve toner charging properties, conveyance properties, mold release properties, etc. shall be.

That is, 1 the developing roller according to the present invention has an electrode layer containing at least a resin and conductive particles in the outermost layer, and the conductive particles are the resin constituting the layer when positively charged toner is used. The basic structure is that the chargeability is more negative than that of the resin, and when a negatively charged toner is used, the chargeability is more positive than that of the resin constituting the layer.

The configuration of a typical developing roller used in the present invention will be explained based on FIG. 2.

FIG. 2 shows a configuration in which an electrode layer 21 is provided on a core metal 22. The core bar 22 is made of a conventionally known material, for example, a metal material such as stainless steel, aluminum, or iron.

The electrode layer 21 is composed of resin and conductive particles.

For the resin layer, alkyd resin, chlorinated polyether, chlorinated polyethylene, epoxy resin, fluororesin, phenol resin, polyamide, polycarbonate, polyethylene, methacrylic resin, polypropylene, polystyrene resin, polyurethane, polyvinyl chloride, polyester resin, etc. Resins such as vinylidene chloride and silicone are used as rubbers, butadiene rubber (BR) and styrene-butadiene rubber (SD
R), ethylene propylene rubber (EPDM), chloroprene rubber (CR), chlorinated polyethylene, epichlorohydrin rubber (CHR), nitrile rubber (NBRR),
Rubbers such as acrylic rubber, urethane rubber, silicone rubber, and fluororubber may be used, but silicone resins and fluororesins are preferably used from the viewpoint of heat resistance and moisture resistance.

Various metals or metal oxides are used as the conductive particles, but from the viewpoint of preventing image retention, if the toner is positively charged, use particles whose chargeability is more negative than that of the resin forming the layer. In addition, when the toner is negatively charged, it is important to select a toner that has more positive chargeability than the resin forming the layer.

For example, when the constituent resin of the electrode layer is a fluororesin (Lumiflon 601C; manufactured by M Glass Co., Ltd.) as in the reference example described later, when a positively charged toner is used as the toner, the conductive particles are more effective than the fluororesin. Ni has strong negative chargeability
When a negatively charged toner is used as the toner, it is desirable to use metal particles such as AQ, Zn, Fe, etc., which have stronger positive IE conductivity than the fluororesin.

The amount of conductive particles used is 1 to 10 parts by weight per 100 parts by weight of the resin.
Parts by weight are preferred; if the amount used is less than 1 part by weight, the effect of the metal particles as an electrode will not be obtained and an afterimage will occur, and if it exceeds 100 parts by weight, filming may occur or 1 part by weight. This is undesirable because it reduces mechanical strength.

In addition, it is desirable to coat the surface of conductive particles with a synthetic resin such as fluororesin, silicone resin, or acrylic resin using a fluidized bed coating device to prevent low resistance due to contact between metal particles. .

Furthermore, inorganic fillers, crosslinking agents, heat stabilizers, processing aids, and the like can be added to the developing roller used in the present invention for various purposes. Inorganic fillers include diatomaceous earth, quartz powder, iron oxide, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, talc, aluminum silicate, aluminum oxide powder, potassium titanate, asbestos,
glass.

Powders such as carbon fiber, Teflon, and boron nitride are used.

Further, as the toner, conventionally known toners can be used as they are. Specific examples of such toner include fine particles containing a coloring agent in a binder resin such as styrene-〇-butyl methacrylate or epoxy resin, and if necessary, a charge control agent such as glosine dye or basic toner. dyes, etc.)
, fluidizers such as silica, abrasives such as silicon carbide, lubricants such as fatty acid metal salts, and the like.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Reference Example Using an apparatus as shown in FIG. 3, the relative chargeability of the resin and conductive particles in the electrode layer of the developing roller used in the present invention was measured.

That is, a fluorine-based copolymer resin film 32 (Lumiflon 601C1 solid content 50%; manufactured by Asahi Glass Co., Ltd.) is mounted on the drum 31, a leg rod 33 with a spherical tip is brought into contact with the film 32, and the drum 31 is rotated 10 times. It is frictionally charged with the leg rod 33. The amount of charge on the resin film at this time was measured using a probe 34 and an electrometer 35 (Model 344; Tre
(manufactured by ck company), and the sign of this measurement value (positive,
The chargeability of the resin and metal was measured from (negative). Next, measurements were carried out in the same manner as above, except that the leg rods were replaced with Zn rods, Fe rods, Ni rods, and Cu rods.

The results are shown in Table-1.

Table 1 [Charging potential of fluorine-based copolymer resin (Lumiflon 601C) when using each metal rod] Example 1 The following electrode layer forming components were spray-coated on the core metal (SUSI), After curing for 1 hour, it was polished to produce a developing roller as shown in FIG.

[1! Polar layer formation] Af1 particles 1111 (average particle size 30.)
10 parts by weight The volume resistance of this electrode layer is 8.0×10”Ω・
The book that is the country Fluorine-based copolymer resin (Lumiflon 60)
The surface is coated with 1C1 Asahi Glass Co., Ltd.

Examples 2 to 5 In Example 1, the AQ particles that are the forming component of the electrode layer were Zn particles (Example 2), Fe particles (Example 3), and Ni
A developing roller was produced in the same manner as in Example 1 except that particles (Example 4) and Cu particles (Example 5) were used.

The developing rollers obtained in each of the Examples obtained as described above were used as the developing rollers shown in FIG. 1, and the image retention was evaluated. The results are shown in Table-2. The evaluation method was as follows.

[Evaluation of afterimage property]

After developing the black solid area, develop the halftone dots, and calculate the ratio (IDL) of the image density (IDL) of the dot corresponding to the position of the black solid area to the image density (IDH) of the dot directly beside the area other than the area corresponding to the black solid area (IDL). /TD
H) was measured using a Macbeth densitometer. The ratio was measured at two locations on the left and right.

Note that the following were used as the toner thin layer blade, replenishment roller, photoreceptor, and toner.

[Toner thin layer blade]

Silicone rubber (1+m thickness) [Toner supply roller] conductive urethane sponge [Photoreceptor] PC 〔toner〕 (Positively charged toner) Styrene acrylic copolymer resin nigrosine dye Carbon black (Negatively charged toner) Styrene acrylic copolymer resin Carbon black Chromium-containing monoazo dye Table-2 It is a negative conductive particle.

100 parts by weight 2 parts by weight 10 parts by weight 100 parts by weight 10 parts by weight 2 parts by weight From Table 2, when using a positively charged toner, conductive particles with strong negative chargeability are used; It can be seen that in the developing device of the present invention, which is equipped with a developing roller in which the electrode layer is made of conductive particles with strong positive chargeability, afterimages can be efficiently prevented.

〔Effect of the invention〕

Since the developing device of the present invention has the above-mentioned configuration, it is possible to prevent afterimages from occurring and to obtain high-quality images without complicating the layer structure of the developing roller. FIG. 3 shows an apparatus for measuring the chargeability of resin and conductive particles.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a developing device according to the present invention, and FIG. 2 is a schematic sectional view of a developing roller used in the present invention. Third
The figure shows an apparatus for measuring the chargeability of resin and conductive particles. 1: Container 2: Toner 3: Agitator 4 = Replenishment roller 5: Developing roller 6: Toner thin layer blade 7: Photoreceptor 22: Core metal 31 Ni drum 33: Metal rod 35: Electrometer 21: Electrode layer 23: Conductive Particle 32: Resin film 34: Potential probe

Claims (1)

[Claims] (1) In a developing device that supplies toner by a replenishment roller onto a developing roller that carries toner on its surface, forms a uniform thin layer on the developing roller by a regulating member, and thereby develops an electrostatic latent image. The roller has an electrode layer containing at least a resin and conductive particles in the outermost layer, and when a positively charged toner is used, the conductive particles have a chargeability that is more negative than that of the resin constituting the layer. Further, when a negatively charged toner is used, the developing device is characterized in that the charging property is more positive than that of the resin constituting the layer.