JPH1039614A - Developing roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the electrifying property of a toner and to heighten the quality of a picture image by sticking particulates, which have specific characteristics and specific size, to the surface of an elastic body layer whose raw material is composed of a hardenable substance having the surface adhering property. SOLUTION: In a developing roller 13, a conductive, elastic body layer 41 consisting of a hardenable conductive composition and a coating layer 42, which was formed by accumulating particulates 42a having electrical and mechanical properties equivalent to those of the toner and a diameter greater than that of the toner, taking advantage of surface adhering property of the conductive, elastic body layer 41, are arranged around a conductive shaft body 40 of a metallic shaft. In this case, the hardenable composition constituting the elastic body layer 41 is preferably made up of a polymer, which is preferable to possess at least one alkenyl group in its molecule and whose repeating unit constituting its principal chain is of an oxy-alkylene unit, and a hardenable conductive composition containing a hardening agent, which possesses at least two hydroxyl groups in its molecule, a hydroxy-generated catalyser, and a conductivity donative substance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing apparatus incorporated in an apparatus employing an electrophotographic system, a back exposure system (so-called chargeless system), or an electrostatic recording system, such as a printer, a copying machine or a facsimile receiver. With regard to the developing roller used in the present invention, it is intended to provide a technique which exhibits the most remarkable effect particularly when a non-magnetic one-component developing system is adopted.

[0002]

2. Description of the Related Art Electrophotographic systems include a system that uses both a magnetic force and an electric force to transfer a developer, and a method that uses only an electric force. In a system using both magnetic and electric acting forces, there are a method using a two-component developer composed of a magnetic carrier and a non-magnetic toner and a method using a one-component developer composed of only a magnetic toner. On the other hand, a method using only the electric acting force uses a one-component developer composed of only a non-magnetic toner (hereinafter, referred to as a non-magnetic one-component developer).

FIG. 3 shows the structure of a developing device in a printer or a copying machine using a non-magnetic one-component developer and its peripheral structure. These configurations will be described first. A photoconductive insulator layer is formed on the surface of the photosensitive drum 1, which is an electrostatic latent image carrier. A photoconductive insulator is a substance which usually shows electrical insulation and shows conductivity when irradiated with light. The photosensitive drum 1 rotates in the rotation direction 1a, and
The surface is uniformly charged. The surface of the photosensitive drum 1 is irradiated with reflected light 10 when scanning the surface of the document with light through an optical system (not shown).
The light-irradiated portion on the surface becomes conductive, and the charge at this portion disappears, whereby an electrostatic latent image is formed on the surface of the photosensitive drum 1. The light irradiation 10 is performed by a light beam whose intensity is modulated corresponding to an image to be recorded in a laser printer, for example. In the copying machine, light that is guided through an optical system and that is the reflected light when the surface of the document is scanned by light becomes the light irradiation 10. When the toner, which is a non-magnetic one-component developer of powder charged from the developing roller 13, is applied to the electrostatic latent image formed on the surface of the photosensitive drum 1, the electrostatic latent image becomes visible. The toner supplied on the surface of the photosensitive drum 1 is transferred to the recording paper 4. At the time of this transfer, the transfer device 5 applies an electrostatic suction force from the back side of the recording paper 4. A cleaning device 6 such as a cleaning blade is provided downstream of the transfer device 5 in the rotation direction 1a. The cleaning device 6 removes toner that has been adsorbed on the surface of the photosensitive drum 1 but has not been transferred onto the recording paper 4. The recording paper 4 to which the toner has been transferred is conveyed to the fixing device 7. The fixing device 7 has a heating roller 8 and a pressure roller 9, and passes the recording paper 4 therebetween, thereby fixing the transferred toner on the recording paper 4.

The developing device 3 has a configuration in which a developing roller 13 is built in a toner container 11 in which a toner 12 is stored.
The toner 12 is applied to the surface of the photosensitive drum 1 by bringing the surface of the developing roller 13 into contact with the photosensitive drum 1. Such a developing method is called a contact type. A supply roller 14 is provided in the toner container 11 to ensure that the toner 12 adheres to the surface of the developing roller 13.
In order to regulate the layer thickness of the toner 12 on the three surfaces, a thin layer forming blade 15 is provided in contact with the developing roller 13.
A negative voltage with respect to the ground potential is applied to the developing roller 13 by, for example, a negative power supply 17, and a negative voltage having a magnitude greater than or equal to the voltage applied to the developing roller in absolute value with respect to the ground potential is applied to the supply roller 14. Is applied by the negative power supply 18,
The toner deposited and deposited on the surface of the developing roller 13 is charged. As the cleaning device 6, a brush or a roller may be used in addition to the illustrated blade system.

[0005]

The structure of the contact type developing device using a non-magnetic one-component developer and its peripheral structure are as described above. However, the following problems are involved in the conventional developing roller. was there.

Since the developing roller is in contact with the photoreceptor, it is required to be soft enough not to damage the photoreceptor, and the contact width in the circumferential direction with the photoreceptor, that is, the nip width is 0.5 to 2 m.
It is preferable that the hardness of the developing roller is in the range of 20 to 50 degrees in Asuka C hardness because about m is required.
NBR (nitrile butadiene rubber), EPDM, silicone, urethane, etc. are used as the material of the developing roller. However, NBR and EPDM alone have too high hardness. Need to be added. At the same time, a vulcanizing agent is generally added to promote cross-linking, but these plasticizers and vulcanizing agents may crystallize or degrade polycarbonate which is a part of the photosensitive drum material. In addition, low molecular weight silicone remaining without being crosslinked tends to bleed on the surface, and has the same problem as NBR. Furthermore, since urethane has high water absorption, there is a problem that the roller resistance decreases in a high humidity environment, and the characteristics as a developing roller change. There is such a problem. When NBR, EPDM, or silicone is used, a protective layer is provided on the surface of the developing roller, for example, to prevent contamination of the photoreceptor and to prevent water absorption when using urethane. . However, if a resin protective layer is provided on the surface of the developing roller, the number of manufacturing steps increases, and it is necessary to select a material for the protective layer that does not adversely affect the photoconductor and the toner.
There is also a problem that it is difficult to select the material, which causes an increase in cost.

[0007] Regardless of the presence or absence of the protective layer and the material, the surface material of the developing roller greatly affects the charging characteristics of the toner and, consequently, the developing characteristics. That is, when outputting an image having a large image density such as a solid black image, the developing roller needs to convey more toner onto the photoreceptor. The toner may be exhausted, and the toner layer thickness on the surface of the developing roller may be reduced. In this case, the charging of the toner is more greatly affected by the surface material of the developing roller. Therefore, it is difficult for the conventional developing roller to suppress the variation in the charging characteristics of the toner due to the difference in the image pattern.

Since the developing roller is required to have a resistance value in a so-called semiconductive region of about 10 ³ to 10 ⁸ Ω, the material of the developing roller is generally provided with some form of conductivity to adjust the roller resistance value. There is a need to. However, since the resistance value of the semiconductive region fluctuates greatly with a slight change in the added amount of the conductivity-imparting agent, it is difficult to control the roller resistance value and obtain a developing roller having a small resistance value variation. There is.

In the case of the color system, a plurality of colors (C, Y,
M, B), and a plurality of developing rollers are used in correspondence with the toners of the plurality of colors. The toners of the respective colors have different charging characteristics due to differences in the color pigments. Therefore, it is difficult to perform stable color development, and it is difficult to match the developing roller and the developing system.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a developing roller capable of stabilizing the charging characteristics of toner and improving the quality of an image. In addition, the cost of forming a protective layer on the surface of the developing roller is eliminated, and a developing roller suitable for color printing is provided.

[0011]

According to the developing roller of the present invention, which solves the above-mentioned problems, the same electrical properties as toner are provided on the surface of an elastic layer made of a curable composition having surface tackiness. Fine particles having mechanical properties and a particle diameter larger than that of the toner are adhered by utilizing the surface tackiness of the elastic layer to form a coating layer on the roller surface.

The curable composition which is a constituent material of the elastic layer comprises: (A) at least one alkenyl group in a molecule;
(B) a curing agent having at least two or more hydrosilyl groups in a molecule, (C) a hydrosilylation catalyst, and (D) a curability containing a conductivity-imparting substance. It is preferable that it is made of a conductive composition.

[0013]

The fine particles forming the coating layer of the developing roller adhere to the surface of the conductive elastic layer due to the adhesiveness.
Therefore, the thickness of the coating layer is determined by the surface tackiness of the conductive elastic layer, but since the surface tackiness is a property inherent to the material of the conductive elastic layer, the thickness of the coating layer depends on the amount of the curing agent added. Can be controlled uniformly. Further, since the roller resistance value depends on the thickness of the coating layer, by uniformly controlling the thickness of the coating layer, the variation in the roller resistance value can be reduced. The fine particles forming the coating layer of the developing roller have the same electrical and mechanical properties as the material of the toner, and the particle size is larger than that of the toner. During this time, more contact is made with the fine particles constituting the coating layer, and the variation in charge of the toner can be reduced. Also, since the fine particles have a larger particle size than the toner and appropriate irregularities are formed on the coating layer,
The effect of increasing the toner transport amount can also be obtained. In addition, since the coating layer of the developing roller is made of a material having the same electrical and mechanical properties as the toner, even if the toner contributing to development is not sufficiently adhered, the coating layer surface is partially exposed. Does not affect the development characteristics. The developing roller of the present invention can be reduced in hardness without using a plasticizer, and since the surface is covered with a coating layer having the same electrical and mechanical properties as the toner, no protective layer is required. There is no need to worry about photoconductor contamination. Moreover, the formation of the coating layer
Since the fine particles are merely attached by utilizing the surface adhesiveness of the conductive elastic layer, the structure of the roller is simple, the number of manufacturing steps is small, and the cost of the developing roller can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, details of the present invention will be described with reference to the drawings. In the following description, the case where a non-magnetic one-component developer is used as the toner will be described as an example, but the toner is not limited to this.

FIG. 1 is an explanatory sectional view showing a schematic structure of the developing roller 33. As shown in FIG. The developing roller 33 is provided with a conductive elastic layer 41 made of a curable conductive composition around a conductive shaft 40 such as a metal shaft, and further utilizing the surface adhesiveness of the conductive elastic layer 41. The coating layer 42 has the same electrical and mechanical characteristics as the toner, and has a coating layer 42 formed by depositing fine particles having a particle size larger than that of the toner.
More specifically, for example, SU having a diameter of about 1 to 12 mm
A conductive elastic body layer 41 having an Asuka C hardness of about 20 to 50 degrees and a thickness of about 1 to 15 mm is provided around a conductive shaft body 40 made of S or aluminum, and a coating layer 42 is provided on the surface thereof. Is an example. Although FIG. 1 shows that the conductive elastic layer 41 is a single layer, the conductive elastic layer having different conductivity and hardness is laminated in a plurality of layers, and the conductivity and hardness of the entire developing roller 33 are adjusted. Good.

FIG. 2 is an enlarged view of the surface of the developing roller. In the drawing, reference numeral 42a denotes fine particles having a larger particle diameter than the toner T, and shows a state in which the fine particles 42a are adhered using the surface adhesiveness of the conductive elastic layer 41 to form the coating layer 42.

The fine particles 42a have the same electrical and mechanical characteristics as the toner. Specific examples of the material include a styrene acrylic or polyester resin, carbon black as a colorant and a resistance control agent, and the like. Preferred are silica, which is an inorganic additive, and a charge control agent.

Since the particle size of the fine particles is larger than that of the toner,
The developing roller, which forms a coating layer with fine particles, has irregularities on the surface, and the toner conveyed thereon repeatedly rubs with the fine particles on the surface of the developing roller. Therefore, immediately before the toner is transferred onto the photosensitive member, the charge amount of the toner is made uniform, and the appearance of the toner having the opposite charge polarity is suppressed. As a result, the variation in charge of the toner is reduced, so that a stable image can be continuously obtained. Also, even if some of the fine particles fall off the coating layer during use, there is no fatal adverse effect on the image quality. It is also a great advantage that material procurement of fine particles is easy.

In the case of the non-magnetic one-component developing method, the particle size of the toner is generally 5 to 20 μm, so that the particle size of the fine particles adhered to the surface of the conductive elastic layer is 8 to 50 μm.
Above all, the thickness is preferably about 10 to 30 μm. When the particle diameter of the fine particles is less than 8 μm, there is no difference between the particle diameters of the fine particles and the toner, and it is difficult to obtain the expected effect (stabilization of the charging characteristics of the toner). Further, when the particle diameter of the fine particles is
If it exceeds μm, the surface properties of the developing roller deteriorate, and the image characteristics such as image unevenness and image defects are adversely affected. The thickness of the coating layer formed by attaching the fine particles is 100 μm or less, preferably 40 μm or less, more preferably 10 to 35 μm.
m.

The fine particles constitute a coating layer of the developing roller, and not only exhibit a function of stabilizing the charging characteristics of the toner, but also function as a resistance adjusting layer of the entire roller.
The conductivity of the conductive elastic layer of the developing roller is such that the resistance value of the entire roller is about 10 ³ to 10 ⁸ Ω, preferably 10 ³ Ω.
It is set to be ⁴ to 10 ⁷ Omega about. However, the roller resistance described here is 5 at each end of the conductive shaft.
This is a value measured by applying a load of 00 g and applying a DC voltage of 100 V. Here, by limiting the thickness of the coating layer to the above range, the resistance value of the developing roller can be uniformly controlled in the range of 10 ³ to 10 ⁸ Ω, or more preferably in the range of 10 ⁴ to 10 ⁷ Ω.

Since the curable conductive composition used in the present invention does not contain a plasticizer, it does not react with the constituent materials of the photoreceptor and does not contaminate the photoreceptor. Even if the unreacted material in the curable conductive composition bleeds on the surface, there is no fear of contamination of the photoreceptor because the coating layer exists on the surface of the developing roller.

The method for forming the coating layer is not particularly limited. For example, the coating layer can be formed by spraying, dipping, roll coating, brushing or the like. Therefore, the cost can be reduced because a resin protective layer, which is conventionally indispensable, is not required, and the material of the developing roller can be selected by focusing only on the electrical properties such as the hardness and the resistance value of the roller.

Finally, the content of the curable conductive composition, which is a constituent material of the conductive elastic layer provided around the conductive shaft, will be described. As specific examples of the curable conductive composition,
For example, component (A), which is a polymer having at least one alkenyl group in the molecule and a repeating unit constituting the main chain is an oxyalkylene unit, a curing agent having two or more hydrosilyl groups in the molecule (B), a component (C) that is a hydrosilylation catalyst, a component (D) that is a conductivity-imparting substance, and curing including the components (A), (B), (C), and (D). And a substance composed of a conductive composition. Of course, a layer made of another composition, for example, a layer made of polyurethane, polysiloxane, NBR, EPDM or the like may be provided below the conductive elastic material layer made of the curable conductive composition. That is. Of course, a layer formed from the curable conductive composition may be all over the outside of the conductive shaft. In this case, low hardness,
A conductive elastic body having characteristics such as low compression set and bleedless can be obtained.

The details of the curable conductive composition will be described below. The component (A) in the curable conductive composition is a component that is cured by reacting with the component (B) as a curing agent to form a cured product having rubber elasticity.

The repeating unit constituting the main chain of the component (A) is an oxyalkylene unit, and the main chain is a compound having two or more active hydrogens as starting materials, for example, ethylene glycol, bisphenol compounds, glycerin, trimethylol. It is produced by polymerizing C2-C4 alkylene oxide using propane, pentaerythritol and the like. Specific examples of the polymer constituting the main chain produced in this manner include, for example, two or more random or block copolymers of polyethylene oxide, polypropylene oxide, polybutylene oxide, ethylene oxide, propylene oxide and butylene oxide. It is preferable that an alkenyl group is introduced at the terminal from the viewpoint of rubber elasticity.

Preferred specific examples of the polymer having at least one alkenyl group in the molecule and the repeating unit constituting the main chain being an oxyalkylene unit include, from the viewpoint of lowering the hardness of the cured product, It is preferable that the repeating unit of the chain is an oxypropylene unit, and when water absorption is required, a copolymer in which a part of the oxypropylene unit is changed to an oxyethylene unit is preferable.

The number of alkenyl groups contained in the component (A) is required to be at least one from the viewpoint of reacting with the component (B), but is preferably 2 to 6.

As the molecular weight of the component (A), the number average molecular weight (Mn) is selected from the viewpoint of the balance between reactivity and low hardness.
500 to 50,000, and even 1000 to 20,000
Are preferred, and the presence of an alkenyl group at the molecular terminal is
It is preferable from the viewpoint of lower hardness.

Next, (B) in the conductive curable composition
The component, a curing agent having at least two hydrosilyl groups in a molecule, is a component (A) wherein the repeating unit having at least one alkenyl group in the molecule and constituting a main chain is an oxyalkylene unit. Is a component that acts as a curing agent for the polymer.

The component (B) contains at least 2
, Preferably 2 to 50, more preferably 2 to 30
, More preferably 2 to 20, even more preferably 3 to 12
Since there are two hydrosilyl groups, each hydrosilyl group reacts with the alkenyl group present in the molecule of component (A) and cures. When the number of the hydrosilyl groups in the component (B) is less than 2, the curing speed when the curable conductive composition is cured by the hydrosilylation reaction becomes slow, and the curing failure often occurs. When the number of the hydrosilyl groups is more than 50, the stability of the curing agent as the component (B), and eventually the stability of the curable conductive composition, deteriorates. It is likely to remain during curing, causing voids and cracks.

In the above case, having one hydrosilyl group means having one SiH, and in the case of SiH ₂ , having two hydrosilyl groups, H bonded to Si is different from Si The better the curability is,
It is also preferable from the viewpoint of rubber elasticity.

The molecular weight of the component (B) is preferably 30,000 or less, more preferably 20,000 or less, in particular, the number average molecular weight (Mn) from the viewpoint of the dispersibility of the component (D) described later and the roller workability. It is preferably 15,000 or less. Considering the reactivity and compatibility with the component (A), 30
0 to 10000 is preferred.

The component (B) as described above is not particularly limited, but for example, a polysiloxane-based curing agent can be suitably used. As specific examples, the following formulas (i) to (ii)
and i) linear and cyclic polyorganohydrogensiloxanes (including modified polyoxyalkylenes, modified styrenes, modified olefins, etc.).

[0034]

Embedded image (M and n are integers, 10 ≦ m + n ≦ 50, 2 ≦ m, 0 ≦
n and R may be a methyl group, a polyoxyalkylene group having a molecular weight of 100 to 10000, or a hydrocarbon group having 2 to 20 carbon atoms and containing one or more phenyl groups. When a plurality of Rs are included, they need not be the same. )

[0035]

Embedded image (M and n are integers, 10 ≦ m + n ≦ 50, 2 ≦ m, 0 ≦
n and R may be a methyl group, a polyoxyalkylene group having a molecular weight of 100 to 10000, or a hydrocarbon group having 2 to 20 carbon atoms and containing one or more phenyl groups. When a plurality of Rs are included, they need not be the same. )

[0036]

Embedded image (M and n are integers, 3 ≦ m + n ≦ 20, 2 ≦ m ≦ 19, 0
≦ n ≦ 18, R is a methyl group, molecular weight is 100 to 1000
The polyoxyalkylene group may have 0 or may be a hydrocarbon group having 2 to 20 carbon atoms and may contain one or more phenyl groups. R
Are not required to be the same. )

In order to further improve the compatibility with the component (A), it is preferable that R has a phenyl group. Further the ease of availability, as the R _{is, -CH 2 -CH 2 -C 6 H} 5, -CH 2 -CH (C
H ₃ ) —C ₆ H ₅ , and from the viewpoint of storage stability,
_{H 2 -CH (CH 3) -C} 6 H 5 are preferred.

Other examples of the component (B) include, for example, the following general formula (1) R ¹ _Xa (1) (wherein X is a group containing at least one hydrosilyl group, and R ¹ is 2-150 monovalent to tetravalent carbon radicals, a
Is an integer selected from 1 to 4, provided that when X contains only one hydrosilyl group, a is 2 or more. And a hydrosilyl group-containing hydrocarbon-based curing agent having an average molecular weight of 30,000 or less.

In the general formula (1), X represents at least one
Represents a group containing a drosilyl group.
Is, for example, -SiH_n(CH_Three)_3-n(However, n = 1
~ 3), -SiH_n(C_TwoH_Five)_3-n(However, n = 1 to
3), -SiH_n(C₆H_Five) _3-n(However, n = 1 to
3), -SiH_Two(C₆H₁₃) And one silicon atom
Only containing hydrosilyl groups,

[0040]

Embedded image

A hydrosilyl group containing two or more silicon atoms, such as

[0042]

Embedded image

[0043]

Embedded image

[0044]

Embedded image

And the like. Hydrosilyl groups derived from various types of polyvalent hydrogen-disiloxanes in the form of chains, branches, and rings are exemplified. In the formula, m units and p units, n units and q units, n units and p units and x units, n units and q units, It is described that y units, m units and n units, and further, m units, n units, p units, and q units are connected by block bonding. However, these may be block bonds or random bonds. The same applies to the following description.

Among the various hydrosilyl groups described above,
(C) The hydrosilyl group-containing hydrocarbon-based curing agent, which is a component, has a low possibility of impairing the compatibility with other organic polymers.
It is preferably at most 00, and in consideration of the reactivity of the hydrosilyl group, the following is preferred.

[0047]

Embedded image

Hereinafter, these groups will be referred to as "groups represented by the formula (8)".

In the general formula (1), R ¹ has 2 to 2 carbon atoms.
It represents 150 monovalent to tetravalent hydrocarbon groups, and may be a group composed of a polymer. As a specific example,

[0050]

Embedded image

[0051]

Embedded image

(These are described in, for example, JP-A-3-95266). Specific examples of the group in which R ¹ is a polymer include ethylene, propylene, 1-butene, isobutylene and the like. A polymer obtained by polymerizing an olefin compound having 2 to 6 carbon atoms as a main monomer and having one to four bonds, butadiene, a diene compound such as isoprene is homopolymerized, or the olefin compound and Examples thereof include those obtained by copolymerizing a diene-based compound and then hydrogenating the compound and having 1 to 4 bonds.

Among the hydrocarbon curing agents represented by the general formula (1) having R ¹ and X as described above, R ¹ is a hydrocarbon group having 5 to 20 carbon atoms, and X is The combination in the case of the shown group increases the reactivity,
It is preferable from the viewpoint of compatibility with the component (B).

Of these, R ¹ has 5 to 12 carbon atoms.
It is preferable that the raw material is easily available, and it is preferable that X is a cyclic polysiloxane compound among the groups represented by the chemical formula (8), since the compatibility with the component (B) is high. It is preferable from the point that it becomes better. Compounds obtained by this combination are preferred as hydrocarbon-based curing agents. For example, for example,

[0055]

Embedded image

And the like.

In the curable conductive composition, a hydrosilylation catalyst as the component (C) is used together with the components (A) and (B). The hydrosilylation catalyst as the component (C) is not particularly limited, and specific examples thereof include solid platinum supported on a carrier such as platinum, alumina, silica, and carbon black, chloroplatinic acid, and platinum chloride. Complexes of acids and alcohols, aldehydes, ketones and the like, platinum / olefin complexes, platinum / phosphite complexes and the like are preferred.

The curable conductive composition further comprises (D)
It contains a conductivity-imparting substance as a component. As the conductivity-imparting substance as the component (D), carbon black,
Fine metal powder, furthermore, an organic compound or polymer having a quaternary ammonium base, a carboxylic acid group, a sulfonic acid group, a sulfate group, a phosphate group, or the like, an ether ester amide, or an ether imide polymer, and ethylene oxide. Examples of the compound include a compound having a conductive unit typified by an epihalohydrin copolymer, methoxypolyethylene glycol acrylate, or a compound imparting conductivity, such as an antistatic agent such as a polymer compound. As the component (D), a plurality of conductivity imparting agents may be used.

The curable conductive composition is prepared from the above components (A) to (D). The hardness of the conductive elastic layer made of such a curable conductive composition is 40 ° or less, preferably 25 ° or less in terms of JISA hardness from the viewpoint of forming a good nip width between the thin layer forming blade and the photoreceptor. And the proportions of the components (A) and (B) used are:
The hydrosilyl group of the component (B) is in an amount of 0.2 to 2.5 mol, more preferably 0.4 to 0.4 mol per mol of the alkenyl group in the component (A).
It is good to use it so that it may be ~ 2.5 mol. Also (C)
The amount of the hydrosilylation catalyst used as the component is from 10 ^-1 to 10 ^-6 mol per 1 mol of the alkenyl group in the component (A). Further, the amount of the conductivity-imparting substance used as the component (D) is 100% in total of the components (A) to (C).
Parts (parts by weight, hereinafter the same), the volume resistivity of the conductive elastic layer is 10 to 50 parts, more preferably 0.3 to 30 parts.
^{About 3} to 10 ¹⁰ Ω · cm, preferably 10 ⁵ to 10 ⁸ Ω
-Used to be cm. If necessary, a non-conductive filler such as silica and magnesium carbonate, an antioxidant, and the like may be added to the curable conductive composition. The amount to be added is usually 100% in total of the components (A) to (D).
The amount is preferably not more than about 50 parts, more preferably not more than about 20 parts with respect to the part, since the rubber hardness is not increased.

[0060]

Next, the developing roller of the present invention will be described in more detail with reference to examples.

Example 1 A number average molecular weight (Mn) of 8,000 and a molecular weight distribution (Mw /
Mn) 2.0 (measured by GPC), viscosity 130P (20
C) 100 g of a polyoxypropylene-based polymer (90% of OH at both ends of polyoxypropylene is allylated).

[0062]

Embedded image Polysiloxane-based curing agent (SiH value 0.35)
6.9 g of chloroplatinic acid (H ₂
10% isopropyl alcohol solution of PtCl ₆ )
06 g and Ketjen Black EC 0.5 g were mixed and defoamed under reduced pressure (10 mmHg, 120 minutes). The obtained curable conductive composition is coated around a stainless steel shaft, and cured in a mold at 120 ° C. for 30 minutes to form a 7.5 mm thick conductive elastic layer around the stainless steel shaft. The provided rollers were manufactured.

Next, a toner having an average particle diameter of 10 μm is aggregated,
Fine particles having an average particle diameter of 25 μm were produced by pulverization, and the fine particles were adhered to the surface of the conductive elastic layer of the obtained roller to form a coating layer, which was used as a developing roller. The outer diameter of the developing roller was measured with an outer diameter measuring device (manufactured by Keyence Corporation), and the thickness of the coating layer was calculated to be about 30 μm. The obtained developing roller was set at a predetermined position of a laser printer manufactured by Seiko Epson Corporation, and image output was evaluated using toner contained in a laser printer cartridge. As a result, the image density is 10% and 100% (black solid image)
In both cases, very good initial images were obtained. The image of 10% density was good even after developing 2,000 sheets.

Example 2 Example 1 was repeated up to the production of the roller provided with the conductive elastic layer.
Was performed in the same manner as described above. Next, a toner having an average particle diameter of 8 μm is aggregated and pulverized to produce fine particles having an average particle diameter of 20 μm, and the fine particles are adhered to the surface of the conductive elastic layer of the obtained roller to form a coating layer. A developing roller was used. When the thickness of the coating layer was calculated in the same manner as in Example 1, it was about 25 μm. The obtained developing roller was set at a predetermined position of a laser printer manufactured by Seiko Epson Corporation, and image development was evaluated using a developer contained in a laser printer cartridge. As a result, very good initial images were obtained for both 10% and 100% image density (solid black image). 1
The image of 0% density was good even after developing 2,000 sheets.

Example 3 The polysiloxane of Example 1 has the formula:

[0066]

Embedded image

A polysiloxane-based curing agent (Si
An image was evaluated under the same conditions as in Example 1 except that the H value was changed to 2.7 g (with an H value of 0.97 mol / 100 g). As a result, a very good image was maintained after development of 2,000 sheets.

Comparative Example 1 Silicone resin (KE12 manufactured by Shin-Etsu Chemical Co., Ltd.)
61-U) was formed by coating on a SUS shaft by an extrusion method to produce a 25 mmφ developing roller. The obtained roller was set at a predetermined position of a laser printer manufactured by Seiko Epson Corporation, and image evaluation was performed using toner contained in a laser printer cartridge. As a result, the initial image having an image density of 10% was good. However, in the image of 100% density (solid black image), although the upper part was good, the image density was lower in the lower part.

[0069]

The developing roller of the present invention has the following effects. 1) Since the coating layer on the surface of the developing roller has the same electrical and mechanical properties as the toner, and is composed of fine particles having a particle size larger than that of the toner, the toner contributing to development is transported during transport. More contact with the fine particles on the surface of the developing roller, it is possible to reduce the variation in the charge of the toner,
Very stable images can be obtained. 2) Since appropriate irregularities are formed on the surface of the coating layer of the developing roller, the amount of transported toner is increased, and a sufficient image density is secured. 3) Since the surface of the developing roller is made of a material having the same electrical and mechanical properties as the toner, even if the toner is insufficiently adhered and the coating layer surface is partially exposed. It does not affect the development characteristics. 4) The hardness of the developing roller can be reduced without using a plasticizer, and since the surface is covered with a material similar to that of the toner, there is no concern about contamination of the photoreceptor without providing a protective layer. 5) Since the formation of the coating layer only involves attaching the fine particles using the surface tackiness of the conductive elastic layer, the structure is simple, the number of manufacturing steps is small, and the cost of the developing roller can be reduced. . 6) When applied to a developing device of a color system, although the charging characteristics of the respective color toners (C, Y, M, B) are different, the surface of the developing roller provided corresponding to each color toner is equivalent to the same color toner. By coating a material having electrical and mechanical properties, stable color development can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing a structure of a developing roller.

FIG. 2 is an enlarged explanatory view of the vicinity of a developing roller surface on which a coating layer made of fine particles larger than toner particles is formed.

FIG. 3 is an explanatory view showing an embodiment of a conventional developing device and its peripheral structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 1a Rotation direction 2 Charger 4 Recording paper 5 Transfer device 6 Cleaning device 7 Fixing device 8 Heating roller 9 Pressure roller 10 Light irradiation 11 Toner container 12 Toner 13 Developing roller 14 Supply roller 15 Thin layer forming blade 40 Conductivity Shaft 41 Conductive elastic layer 42 Coating layer 42a Fine particles T Developer toner

Continued on the front page. (72) Inventor Kenji Kobayashi 2-1-1 Hiei Tsuji, Otsu-shi, Shiga Prefecture Inside Kanebuchi Chemical Industry Co., Ltd. (72) Inventor Yasunori Matsunari 2-1-1 Hiei-tsuji, Otsu City, Shiga Prefecture Kanegafuchi Chemical Industry Inside (72) Inventor Jou Fukuda 2-1-1 Hiei Tsuji, Otsu City, Shiga Prefecture Inside Kanebuchi Chemical Industry Co., Ltd.

Claims (2)

[Claims] 1. A developing roller for use in a developing device, wherein the surface of an elastic layer made of a curable composition having surface tackiness has electric and mechanical properties equivalent to those of a toner, and A developing roller having a coating layer formed on the roller surface by adhering fine particles having a particle size larger than that of the toner by utilizing the surface tackiness of the elastic layer. 2. The curable composition which is a constituent material of the elastic layer has (A) at least one alkenyl group in a molecule,
(B) a curing agent having at least two or more hydrosilyl groups in a molecule, (C) a hydrosilylation catalyst, and (D) a curability containing a conductivity-imparting substance. 2. The developing roller according to claim 1, comprising a conductive composition.