JP2002287481A - Toner carrier, developing device, process cartridge, and manufacturing method for toner carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner carrier which has a stable electric resistance value, is easy to control and superior in recyclability, and can excellently be manufactured by simple manufacturing facilities. SOLUTION: A conductive elastic body layer 3b is formed by using at least thermoplastic elastomer (A) of 15 to 70 mass %, elastomer (B) of 30 to 85 mass % which can be bridged, and a conductive filler (C) of 1 to 20 mass pts. for 100 mass pts. of the thermoplastic elastomer (A) and elastomer (B); and the thermoplastic elastomer (A) has a matrix phase, the elastomer (B) has a dispersion phase, and the conductive filler (C) is selectively made present in the thermoplastic elastomer (A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner carrier and a developing device in an electrophotographic apparatus such as a copying machine and a printer, an electrostatic recording apparatus, and the like, using a conductive thermoplastic elastomer composition.

[0002]

2. Description of the Related Art In recent years, thermoplastic elastomers, which are soft materials like rubber, do not require a cross-linking step, and are easy to recycle, have been attracting attention. Widely used in the fields of medical parts, daily necessities, etc.

[0003] These thermoplastic elastomers have a soft rubber-like feel, and are more moldable, weather-resistant, and vulnerable than vulcanized rubbers.
It has excellent colorability and the like, and has been widely used in terms of cost.

On the other hand, with the progress of electrophotographic technology, demands for conductive members used in each electrophotographic process have been increasing, and in particular, toner carriers used in developing devices have attracted attention. The characteristics required for the toner carrier are not only a predetermined electric resistance value, but also various developing mechanisms such as low hardness, low compression set, and no surface contamination due to bleed such as a softener. It is necessary to add characteristics suitable for

[0005] The developing method in the electrophotographic method is mainly classified into a one-component developing method and a two-component developing method. However, it is necessary to reduce the size of the copying apparatus in order to reduce the weight and size of the electrophotographic apparatus. A developing device using a system toner is often used.

For example, a one-component developer (hereinafter, also referred to as toner) is carried on a toner carrier as a developer carrier, brought into contact with a photosensitive drum, and the toner is transferred from the toner carrier to the surface of the photosensitive drum. Then, a contact developing method for visualizing the electrostatic latent image as a toner image is known. According to this method, since no magnetic material is required, the apparatus can be simplified and downsized easily, and the toner can be easily colored.

In this contact developing method, a toner carrier carrying a toner is brought into contact with a latent image carrier such as a photosensitive drum which retains an electrostatic latent image, and the toner adheres to the latent image on the latent image carrier. In this case, development is performed, and therefore, the toner carrier needs to be formed of an elastic body having conductivity.

That is, in this contact developing method, as shown in FIG. 3, for example, the toner 6 in the toner container 2 is transferred to the photosensitive drum 1 as a latent image carrier rotating in the direction of arrow a in FIG. The toner is supplied onto the photosensitive drum 1 by the toner carrier 3 which is provided facing the photosensitive drum 1. Then, the electrostatic latent image on the photosensitive drum 1 is developed and visualized as a toner image. The toner carrier 3 is driven to rotate in the direction of arrow b with respect to the rotation direction a of the photosensitive drum 1.

Further, in the toner container 2, a developing blade 4 is provided above the toner carrier 3, and an elastic roller 5 is provided at a position upstream of the developing blade 4 in the rotation direction of the toner carrier 3. Is provided.

[0010] With such a configuration, the elastic roller 5 is driven by an arrow c.
, The toner 6 is supplied to the vicinity of the toner carrier 3, and the toner is rubbed at a contact portion (nip portion) where the toner carrier 3 and the elastic roller 5 come into contact with each other. The toner adheres to the body 3.

Then, as the toner carrier 3 rotates, the toner 6 adhered to the toner carrier 3 is transferred to the developing blade 4
The toner is rubbed and rubbed at a contact portion between the toner carrier 3 and the toner carrier 3. The toner carrier 3 is sufficiently triboelectrically charged, forms a thin layer, and is conveyed to the photosensitive drum 1. Then, by applying, as a developing bias, an alternating voltage in which DC and AC are superimposed, for example, between the toner carrier 3 and the photosensitive drum 1, the toner 6 on the toner carrier 3 Is transferred in accordance with the electrostatic latent image, and adheres to the electrostatic latent image. In this way, the electrostatic latent image is developed and visualized as a toner image.

The toner 6 remaining without being consumed in the developing section in the developing section is recovered into the toner container 2 from below the toner carrier 3 as the toner carrier 3 rotates. Most of the collected toner 6 is mixed with the toner 6 in the toner container 2, and the charged charges of the collected toner 6 are dispersed.

Here, the toner carrier 3 must rotate while reliably maintaining a state of being in close contact with the photosensitive drum 1. To realize this, for example, Japanese Unexamined Patent Publication No. 7-3292
As shown in FIG. 2, JP-A No. 14-2003 discloses a conductive elastic layer made of a low-hardness conductive rubber composition or a foam layer 3c made of a conductive foam (base layer) on the outer periphery of a cored bar 3a. Are described, and a toner carrier 3 having a structure in which a conductive resin coating layer 3d (surface layer) in which at least a plurality of layers of a conductive agent is blended is further laminated is described.

[0014]

However, the following problems may occur in the conventional toner carrier as described above.

First, since the conductive elastic layer and the conductive foamed layer are formed from a rubber composition, a vulcanization step is indispensable, which makes equipment and manufacturing steps complicated and difficult to control. There is a risk of becoming.

Second, by forming a three-dimensional network structure by vulcanization, it becomes difficult to recycle materials.

Third, usually, a material in which a conductive filler is dispersed in a bulk has a large electric resistance value greatly depending on molding and processing conditions, so that it is difficult to control the electric resistance value and may lack stability.

An object of the present invention is to provide a toner carrier in which the above problems are improved.

[0019]

According to the present invention for achieving the above object, at least a toner carrier having a conductive elastic layer and a coating layer laminated in this order on an outer periphery of a cored bar is provided. The conductive elastic layer includes a thermoplastic elastomer (A), a crosslinkable elastomer (B), and a conductive filler (C), and a blending amount of the thermoplastic elastomer (A) with respect to the conductive elastic layer. Is 15% by mass
Not less than 70% by mass, and the compounding amount of the crosslinkable elastomer (B) to the conductive elastic layer is 30% by mass.
And 85% by mass or less, and the compounding amount of the conductive filler (C) is 1 part by mass or more and 20 parts by mass with respect to 100 parts by mass of the thermoplastic elastomer (A) and the crosslinkable elastomer (B).
Not more than 1 part by mass, the thermoplastic elastomer (A) forms a matrix phase and is a crosslinkable elastomer (B)
Forms a dispersed phase, the conductive filler (C) is selectively present in the thermoplastic elastomer (A), and the coating layer is a resistance layer. .

The conductive elastic layer of the toner carrier of the present invention comprises a conductive thermoplastic elastomer composition, and preferably comprises at least a thermoplastic elastomer (A);
A step of kneading a crosslinkable elastomer (B) and one or more additives selected from the group consisting of a crosslinking agent, a softening agent and a compatibilizer, and a step of kneading the thermoplastic elastomer (A) in a molten state. And subjecting the crosslinkable elastomer (B) to a cross-linking reaction under a shearing force.

Preferably, the conductive filler (C)
Is added after the crosslinking reaction of the crosslinkable elastomer (B).

By employing the above manufacturing method, the thermoplastic elastomer (A) is used as the matrix phase, the crosslinkable elastomer (B) is used as the dispersed phase, and the conductive filler (C) is used as the thermoplastic elastomer (A). )). The conductive filler (C) being selectively present in the thermoplastic elastomer (A) means that the conductive filler (C) is not substantially present in the crosslinkable elastomer (B). Means that. As a result, the dispersion state of the conductive filler in the conductive path can be stabilized.

The toner carrier in which the conductive elastic layer as described above is formed on the outer periphery of the cored bar is manufactured by extrusion molding or injection molding using equipment such as a conventional extruder or injection molding machine. Therefore, it can be manufactured at a relatively low cost by a simple manufacturing process. Further, in the obtained toner carrier, low hardness, low compression set, bleeding of the surface due to a softening agent and the like are suppressed, and stable electric resistance control of the roller as a whole is possible.

In particular, from the viewpoint of a low-hardness toner carrier,
The JIS-A hardness of the toner carrier surface is 15 ° or more and 50 or more.
° or less, more preferably 40 ° or less. If the JIS-A hardness is 50 ° or less, a sufficient nip width can be secured, and if the JIS-A hardness is 15 ° or more, bleeding or the like of the softener can be suppressed.

Further, from the viewpoint of a toner carrier having a small compression set, specifically, it is preferably 20% or less, and within this range, surface bleeding due to a softener or the like can be suppressed.

In addition, the toner carrier in which the conductive elastic layer as described above is formed on the outer periphery of the metal core is easy to recycle.

The toner carrier of the present invention is suitable for a developing device that forms a thin layer of toner on the surface of the toner carrier and supplies the thin layer to the latent image carrier to develop a latent image on the latent image carrier. Can be arranged.

A process cartridge in which at least the latent image carrier and the developing device are integrally formed as a cartridge, and is a process cartridge detachable from the image forming apparatus main body. The toner carrier of the present invention can be suitably arranged in a process cartridge in which one-component toner is carried and transported from the toner accommodating container to the developing section.

More specifically, a non-magnetic one-component toner is carried on a toner carrier having the above-mentioned conductive elastic layer formed on the outer periphery of a cored bar to form a thin layer of toner. In the state, the electrostatic latent image is brought into contact with the latent image carrier holding the surface, and the developer is attached to the electrostatic latent image on the surface of the latent image carrier from the thin layer,
By using a developing device provided with a toner carrier for visualizing the electrostatic latent image and a roller or drum-shaped latent image carrier for holding the electrostatic latent image on the surface, a non-magnetic one component is formed on the outer peripheral surface. The non-magnetic one-component toner adheres to the electrostatic latent image on the surface of the latent image carrier by contacting the surface of the latent image carrier with the toner and rotating in conjunction with the rotation of the latent image carrier. By doing so, the electrostatic latent image can be well visualized.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

As shown in FIG. 1, the toner carrier of the present invention has a core metal 3a and at least a conductive elastic layer 3b and a coating layer 3d as a resistance layer formed on the outer periphery.

Here, the core metal 3a is not particularly limited as long as it has good conductivity.

The conductive elastic layer 3b is made of a conductive thermoplastic elastomer composition containing a thermoplastic elastomer (A), a crosslinkable elastomer (B) and a conductive filler (C).

As the thermoplastic elastomer (A), a styrene-based thermoplastic elastomer is preferable from the viewpoint of flexibility.

As the styrene-based thermoplastic elastomer, at least two polymer blocks A mainly obtained from a vinyl aromatic monomer and a conjugated diene-based monomer are used from the viewpoint of low compression set. A block copolymer consisting of at least one polymer block B obtained more mainly, and a block copolymer obtained by hydrogenating the block copolymer;
Alternatively, the mixture is preferably a mixture of the block copolymer and the hydrogenated product.

As the block copolymer, ABA,
Examples thereof include a vinyl aromatic compound-conjugated diene compound block copolymer having a structure such as BABA, ABAABA, and the like. Also referred to as a hydrogenated block copolymer, (hydrogenated) block copolymer means a block copolymer and / or a hydrogenated block copolymer. The (hydrogenated) block copolymer preferably contains a vinyl aromatic compound in an amount of 5% by mass or more and 60% by mass or less, and more preferably contains 20% by mass or more and 50% by mass or less.

The polymer block A mainly composed of a vinyl aromatic compound is preferably composed of only a vinyl aromatic compound. Further, a copolymer block of a vinyl aromatic compound, preferably more than 50% by mass, more preferably 70% by mass or more, and a (hydrogenated) conjugated diene compound is preferable. In addition, the (hydrogenated) conjugated diene compound means a conjugated diene compound and / or a hydrogenated conjugated diene compound.

Further, as the polymer block B mainly composed of a (hydrogenated) conjugated diene compound, a polymer block composed of only a (hydrogenated) conjugated diene compound is preferable. Further, a copolymer block of a vinyl aromatic compound and a (hydrogenated) conjugated diene compound of preferably more than 50% by mass, more preferably 70% by mass or more is preferable.

In addition, in each of the polymer block A mainly composed of a vinyl aromatic compound and the polymer block B mainly composed of a (hydrogenated) conjugated diene compound, the vinyl compound or ( Hydrogenated)
Examples of the distribution of the conjugated diene compound include random, tapered (the monomer component increases or decreases along the molecular chain), partially block-like, or any combination thereof. Further, a polymer block A mainly composed of a vinyl aromatic compound or (hydrogenated)
When there are two or more polymer blocks B mainly composed of a conjugated diene compound, they may have the same structure or different structures.

(Hydrogenated) As the vinyl aromatic compound constituting the block copolymer, for example, one or more kinds selected from styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene and the like are selected. Of which styrene is preferred. Further, as the conjugated diene compound, for example, one or more kinds are selected from butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene and the like.
Isoprene and combinations thereof are preferred.

The microstructure of the polymer block B mainly composed of a conjugated diene compound can be arbitrarily selected.
In the butadiene block, the 1,2-microstructure is preferably from 20% to 50%, particularly preferably from 25% to 45%. In the polyisoprene block, 70 to 100% by mass of the isoprene compound is 1,4-
Preferred are those having a microstructure and at least 90% of the aliphatic double bonds based on the isoprene compound are hydrogenated.

The weight average molecular weight of the (hydrogenated) block copolymer having the above-mentioned structure is preferably from 5,000 to 1,500,000, more preferably from 10,500.
000 or more and 550,000 or less, more preferably 10
It is in the range of not less than 0000 and not more than 550,000, particularly preferably not less than 100,000 and not more than 400,000. The molecular weight distribution (the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Wn) (Mw / Mn)) is preferably 10 or less, more preferably 5 or less, and more preferably
2 or less.

The molecular structure of the (hydrogenated) block copolymer is as follows:
It may be linear, branched, radial or any combination thereof.

The method for producing these block copolymers is not particularly limited, and typical methods include, for example,
As described in JP-A No. 0-23798, a method of performing block polymerization in an inert solvent using a lithium catalyst or a Ziegler-type catalyst can be used.

The hydrogenated block copolymer can be obtained by hydrogenating the block copolymer obtained by these methods in an inert solvent in the presence of a hydrogenation catalyst.

Specific examples of the (hydrogenated) block copolymer include SBS, SIS, SEBS, and SEPS. Particularly, a polymer block A mainly composed of styrene and a polymer block mainly composed of isoprene,
The polymer block B has a 1,4-microstructure in which at least 90% by mass and 100% by mass have a 1,4-microstructure and at least 90% of an isoprene-based aliphatic double bond is hydrogenated, and has a weight average molecular weight of 50, 000 or more and 550,000
The following are preferred. More preferably, 90 to 100% by weight of isoprene has a 1,4-microstructure.

A commercially available compound of a styrene-based elastomer can also be used.

On the other hand, the crosslinkable elastomer (B) is preferably one containing an olefin copolymer rubber from the viewpoint of low heat deterioration during mixing.

Examples of the olefin copolymer rubber include ethylene-propylene copolymer rubber, ethylene-propylene-nonconjugated diene rubber, ethylene-butene-nonconjugated diene rubber, and propylene-butadiene copolymer rubber. As described above, an amorphous random elastic copolymer containing an olefin as a main component is preferable, and among them, an ethylene-propylene-nonconjugated diene rubber is preferable. Examples of the non-conjugated diene include dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylene norbornene, and ethylidene norbornene, with ethylidene norbornene being particularly preferred.

As a more preferred specific example, the propylene content is preferably from 10% by mass to 55% by mass, more preferably from 20% by mass to 40% by mass, and the non-conjugated diene content such as ethylidene norbornene. Is preferably 1% by mass or more and 30% by mass or less, preferably 3% by mass or less.
Ethylene-propylene-ethylidene norbornene copolymer rubber (hereinafter referred to as “EP
DM ". ). When the propylene content is 10% by mass or more, sufficient flexibility can be secured, and when the propylene content is 55% by mass or less, sufficient mechanical properties can be secured. When the content of non-conjugated diene typified by ethylidene norbornene is 1% by mass or more, sufficient mechanical properties can be secured, and when it is 30% by mass or less, good injection moldability can be realized. In addition, what was manufactured by a well-known method can be used as EPDM.

Further, the olefin copolymer rubber 100
Mooney viscosity at 100 ° C (ML _{1 + 4} , 100 ° C) is 120
It is preferably at least 350 and at most 140 and at least 30
More preferably, it is 0 or less. If the Mooney viscosity at 100 ° C. (ML _{1 + 4} 100 ° C.) is 120 or more, sufficient mechanical properties can be secured, and if it is 350 or less, a toner carrier having a sufficiently smooth surface can be produced.

In particular, when EPDM having a Mooney viscosity of 120 or more and 350 or less is used, the mechanical properties are large, the tensile strength at break and the elongation at break can be dramatically improved, and the mechanical properties, especially Strength and compression set can be improved.

The olefin copolymer rubber 10 as described above
0 parts by mass is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, preferably 150 parts by mass or less, more preferably 120 parts by mass or less for the purpose of improving processability and mechanical properties. It is used as an oil-extended olefin copolymer rubber by adding a system softener.

Mineral oil-based softeners are classified into paraffinic, naphthenic and aromatic based on the blended high-boiling petroleum fraction, but paraffinic is preferably used. When the addition amount is 20 parts by mass or more, sufficient fluidity of the thermoplastic elastomer composition can be ensured, and particularly excellent extrusion processability and injection moldability can be realized. On the other hand, when the amount is 150 parts by mass or less, good processability can be realized by appropriate plasticity, and good physical properties of the toner carrier can be realized.

100 ° C. of oil-extended olefin copolymer rubber
The Mooney viscosity (ML _{1 + 4} , 100 ° C.) is preferably 30 or more, more preferably 40 or more, preferably 100 or less, and more preferably 90 or less. If it is 30 or more, good mechanical properties can be realized, and if it is 100 or less, good moldability can be realized.

E having a Mooney viscosity of 120 or more and 350 or less
When a large amount of a mineral oil-based softening agent is added to PDM, a thermoplastic elastomer composition capable of simultaneously satisfying the improvement of processability by securing flexibility and the improvement of fluidity and the improvement of mechanical properties can be obtained. Can be. In general, a mineral oil-based softener is used as a fluidity improver in an olefin-based thermoplastic elastomer composition. According to the research of the present researchers, when oil-extended EPDM is not used, EPDM is used.
Regardless of the viscosity of EPDM, when 40 parts by mass or more of a mineral oil-based softening agent is blended with respect to 100 parts by mass of EPDM, bleeding of the softening agent tends to occur on the surface of the conductive elastic layer, and contamination and sticking of the product may occur. May be seen.

However, the Mooney viscosity at 100.degree.
Using oil-extended EPDM premixed with 0 to 150 parts by mass of a mineral oil-based softener, there is no bleeding of the softener, no contamination or stickiness of the product is observed, and breaking strength, elongation at break, compression A conductive thermoplastic elastomer composition having excellent physical properties such as permanent set can be obtained. As described above, although the blending ratio of the mineral oil-based softening agent is large, the bleeding of the softening agent is not recognized because the use of EPDM having a high Mooney viscosity is the upper limit of the allowable oil spreading amount of the mineral oil-based softening agent. It is considered that the softening agent suitably added in advance is uniformly dispersed in EPDM.

In order to improve the compatibility between the thermoplastic elastomer (A) and the crosslinkable elastomer (B), a compatibilizer may be used. This reduces the interfacial tension at the interface between the thermoplastic elastomer (A) forming the matrix phase and the crosslinkable elastomer (B) forming the dispersed phase during kneading, so that the dispersed particle diameter can be reduced. By reinforcing the interface, the mechanical properties can be improved.

The peroxide used for the crosslinking reaction of the crosslinkable elastomer (B) is not particularly limited. For example, benzoyl peroxide, p-chlorobenzoyl peroxide, azobisisobutyronitrile, 2,5-dimethyl-2,5
-Di (t-butylperoxy) hexyne, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane,
2,2′-bis (t-butylperoxy) -p-diisopropylbenzene, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane,
5,5-trimethylhexanoyl peroxide, 2,
4-dichlorobenzoyl peroxide, cyclohexanone peroxide, t-butyl peroxybenzoate, dicumyl peroxide, t-butyl hydroperoxide, t-butyl peroxide, di-t-butyl peroxide, cumene hydroper Oxide or the like can be used.

The amount of the organic peroxide to be used is 0.5 parts by mass or more per 100 parts by mass of the crosslinkable elastomer (B).
The amount is preferably 0 parts by mass or less, more preferably 1 part by mass or more and 5 parts by mass or less. By using 0.5 parts by mass or more of an organic peroxide, a sufficient crosslinking density can be realized,
Sufficient rubber elasticity can be obtained. On the other hand, by using 10 parts by mass or less of an organic peroxide, problems such as foaming during vulcanization molding can be suppressed.

In the present invention, a crosslinking aid can be used in combination to improve the crosslinking efficiency at the time of vulcanization with an organic peroxide. Examples of the crosslinking assistant include p, p'-dibenzoylquinone dioxime, quinone dioxime, triallyl cyanurate, sulfur, ethylene dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, N , N'-m-phenylenebismaleimide, triallyl isocyanurate, trimethylolpropane trimethacrylate and the like can be used. The amount of the crosslinking aid used is 0.0 to 100 parts by mass of the crosslinkable elastomer (B).
It is preferably from 1 part by mass to 5.0 parts by mass. If it is 0.01 parts by mass or more, a uniform and mild crosslinking reaction occurs,
The mechanical properties can be improved, and a sufficient addition effect can be realized. On the other hand, if it is 5.0 parts by mass or less, it is economically advantageous.

The degree of crosslinking of the crosslinkable elastomer (B) greatly varies depending on the timing and method of adding the crosslinking agent. The crosslinkable elastomer (B) is roughly classified into a completely crosslinked type having almost no uncrosslinked portion and a partially crosslinked type having an uncrosslinked portion. A completely crosslinked type having almost no is preferred.

The conductive filler (C) used in the present invention
As EC (Extra Conductive)
e), ECF (Extra Conductive F)
urnace), SCF (Super Conductor)
live Furnace), CF (Conductive)
e Furnace), acetylene black, etc. (including Ketjen Black EC (trade name)), SAF (Sup)
er AbrasionFurnace), ISAF
(Intermediate SAF), HAF (Hi
gh Abrasion Furnace), FEF
(Fast Extrusion Furnace),
GPF (General Purpose Furna)
ce), SRF (Semi Reinforcing)
Furnace), FT (Fine Furnac)
e), MT (Medium Thermal) carbon black such as; Al-doped ZnO, SnO ₂ (antimony oxide-doped) the genus TiO _2, SnO ₂ (oxidation Anchimodopu) the genus SnO _2, SnO ₂ target genus TiO _2, K ₂ O・ NT
metal oxides such as iO ₂ / SnO ₂ Sb ₂ O ₆ and SnO ₂ (antimony oxide-doped) complex oxides; copper powder, silver powder,
A simple metal such as aluminum powder can be used. Among them, carbon black is inexpensive and easy to control the conductivity in a small amount.

The amount of the conductive filler (C) is from 1 part by weight to 20 parts by weight based on 100 parts by weight of the thermoplastic elastomer (A) and the crosslinkable elastomer (B). It is preferably used in a range of not less than 15 parts by mass and not more than 15 parts by mass.

The volume resistivity of the conductive thermoplastic elastomer composition constituting the conductive elastic layer is 1 × 10 ³ Ω · cm or more and 1 × 10 ¹⁰
It is preferable to be Ω · cm or less.

Further, it is possible to eliminate unevenness in volume resistivity,
Conductive fillers to reduce unit-to-unit variation
The volume resistivity is 1 × 10⁰Ωcm or less, suitable
Is 5 × 10^-1Ω · cm or less and volume resistivity of 1 ×
10¹Ω · cm or more 1 × 10^{1 0}Ω · cm or less, preferably
Is 1 × 10^FiveUse in combination with Ω · cm or less
Preferably.

The conductive elastic layer is formed by mixing a mixture of a thermoplastic elastomer (A) and a crosslinkable elastomer (B).
The thermoplastic elastomer (A) is preferably produced by a method including a step of heating to a temperature equal to or higher than the melting point of the thermoplastic elastomer (A) and applying a sufficient shearing force during melting to crosslink the crosslinkable elastomer (B). This method is a method called dynamic crosslinking, but by using this method, mechanical properties and the like are dramatically improved. The apparatus used is not particularly limited, and a batch-type kneader such as a roll, a Banbury mixer, or a kneader, or a continuous kneader such as a screw extruder or a rotor-type continuous kneader may be used alone or in combination. Particularly, a twin-screw kneader is preferable.

The time for adding the conductive filler (C) is preferably after the crosslinking reaction of the crosslinkable elastomer (B) is completed. This is because the conductive filler (C) is selectively dispersed in the thermoplastic elastomer (A). When the thermoplastic elastomer (A), the crosslinkable elastomer (B) and the conductive filler (C) are dry-blended in the early stage of the production, the conductive filler (C) is also dispersed in the crosslinkable elastomer (B). Because of this tendency, desired electrical characteristics may not be realized.

By selectively presenting the conductive filler (C) in the thermoplastic elastomer (A), a small amount of the conductive filler (C) can be used to produce a toner carrier having desired performance. can do.

The increase in hardness due to the addition of the conductive filler (C) can be suppressed by setting the ratio of the thermoplastic elastomer (A) / crosslinkable elastomer (B) to an appropriate value. For example, as the proportion of the crosslinkable elastomer (B) increases, the hardness of the conductive thermoplastic elastomer composition decreases. Further, the crosslinked finely dispersed structure of the crosslinkable elastomer (B) greatly contributes to flexibility and recovery of deformation, and reduces compression set, which is a drawback of the thermoplastic elastomer.

The toner carrier of the present invention can be incorporated in a developing device using a non-magnetic one-component developer. Specifically, as shown in FIG. 3, an elastic roller 5 for supplying toner and an electrostatic roller 5 are used. A toner carrier 3 is disposed between the photosensitive drum 1 which is a latent image carrier holding a latent image in contact with the photosensitive drum 1, and toner 6 is supplied to the toner carrier 3 by an elastic roller 5. Then, the toner is supplied to the photosensitive drum 1 from the thin layer, and the toner is attached to the electrostatic latent image on the photosensitive drum 1 to visualize the latent image.

The photosensitive drum 1 rotates in the direction of arrow a in the figure, and the toner carrier 3 is driven to rotate in the direction of arrow b with respect to the rotation direction a of the photosensitive drum 1. The elastic roller 5
Rotates in the direction of arrow c.

The toner 6 remaining without being consumed in the development in the developing section is collected into the toner container 2 from the lower portion of the toner carrier 3 as the toner carrier 3 rotates. Most of the collected toner 6 is mixed with the toner 6 in the toner container 2, and the charged charges of the collected toner 6 are dispersed.

[0074]

EXAMPLES The present invention will be described below in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Unless otherwise specified, “parts” and “%” represent “parts by mass” and “% by mass”, respectively.
Commercially available high-purity reagents were used.

Example 1 Mixing ratio (parts by mass) shown in Table 1
Thus, a conductive elastic body layer was produced according to the following procedure.

First, as a thermoplastic elastomer, 5 mm
40.0 parts by mass of an oil-extended olefin copolymer rubber (trade name: Esplen 600F, manufactured by Sumitomo Chemical Co., Ltd.) formed into a square pellet of 5 mm x 5 mm, 0.4 part by mass of stearic acid, and an antioxidant As trade name Irganox 101
0 (manufactured by Ciba-Geigy), 1.2 parts by mass of NF Bisomer Ethylene Glycol Dimethacrylate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a crosslinking aid, and peroxide functioning as a crosslinking agent 2,5-dimethyl-2,5-
Di (t-butylperoxy) hexyne (Nippon Oil & Fats Co., Ltd.)
0.8 parts by mass) and SEPTON CJ103 (Kuraray Co., Ltd.) as a styrene-based thermoplastic elastomer
60.0 parts by mass using a Henschel mixer.
Blended uniformly for 0 minutes. This blend was subjected to a dynamic heat treatment at 185 ° C. for 150 seconds using a twin-screw kneader to obtain a thermoplastic elastomer composition.

Next, 9.0 parts by mass of VULCA XC-72 (manufactured by Cabot) as a conductive filler were added to a total of 100 parts by mass of the thermoplastic elastomer and the styrene-based thermoplastic elastomer using a Henschel mixer. Blend uniformly for 10 minutes. This blend was extruded onto a tube at 200 ° C. using a single-screw extruder equipped with a crosshead, while simultaneously inserting a core metal coated with an adhesive layer. Then, this is polished to a thickness of 4.0 m.
m, a conductive elastic roller having an outer diameter of 16 mm and a length of 240 mm were obtained.

Further, while rotating the obtained conductive roller, UV irradiation (10 J / cm ² ) was performed for 4 minutes by a UV lamp (800 W).

Subsequently, a coating layer to be a resistance layer was formed.
That is, a water-soluble urethane resin (trade name: Superflex E-2000, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used with a sand mill so that carbon black (trade name: Toka Black # 7360SB, manufactured by Tokai Carbon) was 16% by mass. Dispersed.

The obtained liquid (solid content: 30%) was applied by dipping. The conditions were as follows: the conductive elastic roller was pulled up in the liquid at a speed of 80 mm / sec, and the coating was performed again upside down so that the coating film thickness became 20 μm. In this way, by performing the coating with the film inverted, the difference in the coating thickness between the upper and lower portions of the roller can be reduced. The coated roller was dried at 150 ° C. × 10 min.
In this embodiment, a dipping coating method is used, but a roll coating method, a beam coating method, or the like can be used as appropriate.

The characteristics of the toner carrier obtained above were evaluated as follows.

(Morphological Observation) A thin film section of the conductive elastic layer of the toner carrier was cut out using a microtome, and observed with a transmission electron microscope (TEM).
As a result, it was found that the thermoplastic elastomer (A) formed a matrix phase, and the crosslinkable elastomer (B) formed a dispersed phase. It was also found that substantially all the conductive filler (C) was present in the thermoplastic elastomer (A).

(Hardness) Diameter 29 mm, thickness 12.5 mm
According to JIS K 6301, using a disk piece of
The JIS-A hardness was measured under the conditions of 23 ° C. × 50% RH. As a result of the measurement, it was 35 °.

(Compression permanent set) Diameter 29 mm, thickness 12.
A 5 mm disc piece was compressed 25% under the conditions of 40 ° C. and 168 hours, and then left for 24 hours in an atmosphere of 23 ° C. × 50% RH, and the compression set was measured in accordance with JIS K 6301. . As a result of the measurement, it was 19%.

(Roller Resistance) The prepared toner carrier is brought into contact with a cylindrical metal drum, and in a rotated state, a voltage of 400 V DC is applied between the cored bar and the metal drum to connect the toner carrier in series with the metal drum. The electrical resistance of the toner carrier as a whole was measured by measuring the voltage applied to the resistor. From this value, the volume resistivity was calculated using the contact area between the toner carrier and the metal drum and the thickness of the toner carrier. As a result, it was 3.5 × 10 ⁵ Ω · cm. Further, the ratio of the absolute value of the difference between the maximum electric resistance value and the minimum electric resistance value when the toner carrier was rotated once to the maximum electric resistance value was measured as the peripheral unevenness of electric resistance. As a result of the measurement, it was 0.31.

(Drum Contamination) The prepared toner carrier was pressed against an unused photosensitive drum by applying a load of 4.9 N to each of the shaft portions at both ends, and was pressed in a greenhouse environment of 40 ° C. × 95% RH. Left for one month. Then, the photoreceptor is observed, and when a roll mark is not recognized, it is indicated by ○, and when it is recognized, it is indicated by ×,
Drum fouling was evaluated. As a result of the measurement, no contamination of the photoreceptor was observed.

(Image Retrieval) The prepared toner carrier is mounted on an environmental unit, and contains a non-magnetic one-component toner.
Under a low-temperature and low-humidity environment of 10 ° C. × 10%, using a laser beam printer (Lasershot; manufactured by Canon), 6000
Images were output up to sheets. The initial image state was compared with the image state at the time of output of 6000 sheets, and an image was obtained.

In addition, the resistance layer was removed by polishing, and the conductive elastic layer of the toner carrier could be easily recycled.

[Examples 2 to 4] A toner carrier was prepared in the same manner as in Example 1 except that the composition of the conductive thermoplastic elastomer forming the conductive elastic layer was changed as shown in Table 1. , Properties were evaluated. As shown in Table 1, various characteristics were good.

The resistance layer was removed by polishing, and the conductive elastic layer of the toner carrier could be easily recycled.

[0092]

[Table 1]

Comparative Example 1 As shown in Table 2, a styrene-based thermoplastic elastomer (trade name: SEPTON CJ10)
3 (manufactured by Kuraray Co., Ltd.) and 100 parts by mass of a conductive filler (VULAXC-72 (manufactured by Cabot)) were simply added in an amount of 15 parts by mass, and a toner carrier was prepared in the same manner as in Example 1. Was evaluated.

The JIS-A hardness is 42 ° and the compression set is 1
9%. In addition, since the dispersion state of the conductive filler was not uniform, the peripheral unevenness of the roller resistance became large, and a defect occurred in image display.

Comparative Example 2 As shown in Table 2, the same procedure as in Example 1 was carried out except that 90 parts by mass of an oil-extended olefin copolymer rubber (trade name: Esplen 600F, manufactured by Sumitomo Chemical Co., Ltd.) was used. An attempt was made to produce a toner carrier. However, the thermoplastic elastomer did not form a matrix phase and could not be kneaded.

Reference Example 3 As shown in Table 2, a non-oil-extended olefin copolymer rubber (trade name: Esplen 501A, trade name:
Using Sumitomo Chemical Co., Ltd.), a toner carrier was produced in the same manner as in Example 1, and the characteristics were evaluated.

Non-oil-extended olefin copolymer rubber used
Mooney viscosity at 100 ° C (ML _{1 + 4}, 100 ° C)
43 and the compression set was 32%. others
Distortion occurs in the contact area with the photosensitive drum during image output.
Tended to stay. As a result, contact
And the image tends to have white spots.

[Comparative Example 4] As shown in Table 2, conductive filler trade name VULCA XC-72 (manufactured by Cabot)
Was used in the same manner as in Example 1 to evaluate the characteristics.

The JIS-A hardness is 55 ° and the compression set is 2
5%. For this reason, uniform contact with the photosensitive drum could not be obtained in image formation, a stable nip could not be formed, and density unevenness occurred.

[Reference Example 5] As shown in Table 2, instead of the styrene-based thermoplastic elastomer, a PVC-based elastomer (trade name: Sunplane F1469, manufactured by Mitsubishi Kasei Vinyl)
A toner carrier was prepared in the same manner as in Example 1 except for using, and the characteristics were evaluated.

The JIS-A hardness is 25 ° and the compression set is 1
6%. In the contamination test, the plasticizer added to the PVC elastomer migrated to the photosensitive drum surface,
The surface was liable to change in quality and leave traces. Even when displaying images,
The toner tends to adhere and solidify.

[0102]

[Table 2]

[0103]

As described above, by using the toner carrier of the present invention provided with the conductive elastic layer made of the conductive plastic elastomer composition, low hardness, low compression set and softening agent can be obtained. Thus, it is possible to provide a toner carrier and a developing device that can suppress surface bleeding due to the above-mentioned factors and can be manufactured at a relatively low cost by a simple manufacturing process.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a structural example of a toner carrier of the present invention.

FIG. 2 is a schematic cross-sectional view for explaining a structural example of a conventional toner carrier.

FIG. 3 is a schematic cross-sectional view for explaining a structural example of a process cartridge.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum (latent image carrier) 2 Toner container 3 Toner carrier 3a Core 3b Conductive elastic layer 3c Foam layer 3d Coating layer 4 Developing blade 5 Elastic roller 6 Toner

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Claims (14)

[Claims] 1. A toner carrier in which a conductive elastic material layer and a coating layer are laminated in this order at least on the outer periphery of a core metal, wherein the conductive elastic material layer is made of a thermoplastic elastomer (A), which can be crosslinked. The thermoplastic elastomer (A) with respect to the conductive elastic layer is 15% by mass.
Not less than 70% by mass and the blending amount of the crosslinkable elastomer (B) with respect to the conductive elastic layer is 30% by mass.
And 85% by mass or less, and the compounding amount of the conductive filler (C) is 1 part by mass or more and 20 parts by mass with respect to 100 parts by mass of the thermoplastic elastomer (A) and the crosslinkable elastomer (B).
Not more than 1 part by mass, the thermoplastic elastomer (A) forms a matrix phase and is a crosslinkable elastomer (B)
Forms a dispersed phase, the conductive filler (C) is selectively present in the thermoplastic elastomer (A), and the coating layer is a resistance layer. 2. The conductive elastic layer is at least one selected from the group consisting of a thermoplastic elastomer (A), a crosslinkable elastomer (B), a crosslinking agent, a softener, and a compatibilizer. And a step of subjecting the crosslinkable elastomer (B) to a crosslinking reaction under shearing force in a state where the thermoplastic elastomer (A) is molten. 2. The toner carrier according to claim 1, wherein the toner carrier is a toner carrier. 3. The toner carrier according to claim 2, wherein the conductive filler (C) is added after a crosslinking reaction of the crosslinkable elastomer (B). 4. The toner carrier according to claim 1, wherein the thermoplastic elastomer (A) is a styrene-based thermoplastic elastomer. 5. The styrenic thermoplastic elastomer comprises at least two polymer blocks A mainly obtained from a vinyl aromatic monomer and a polymer block B mainly obtained from a conjugated diene monomer. 5. A block copolymer comprising at least one of the following: a block copolymer obtained by hydrogenating the block copolymer, or a mixture of the block copolymer and the hydrogenated product. Toner carrier. 6. The crosslinkable elastomer (B) comprises 10
Mooney viscosity at 0 ° C (ML _{1 + 4} , 100 ° C) is 120
Olefin-based copolymer rubber 100 of not less than 350
The toner carrier according to any one of claims 1 to 5, wherein the toner carrier is an oil-extended olefin-based copolymer rubber containing 20 parts by mass and 150 parts by mass or less of a mineral oil-based softener. 7. The oil-extended olefin-based copolymer rubber 1
Mooney viscosity at 00 ° C (ML _{1 + 4} , 100 ° C) is 3
7. The toner carrier according to claim 6, wherein the number is from 0 to 100. 8. The toner carrier according to claim 6, wherein the olefin copolymer rubber is an ethylene-propylene-non-conjugated diene rubber. 9. The ethylene-propylene-nonconjugated diene rubber has a propylene unit content of 10% by mass or more and 55% by mass or less and an ethylidene norbornene unit content of 1% by mass or more and 30% by mass or less. 9. The toner carrier according to claim 8, wherein the toner carrier is an ethylene-propylene-ethylidene norbornene copolymer rubber. 10. The JIS-A hardness is 15 ° or more and 50 ° or more.
The toner carrier according to claim 1, wherein: 11. A latent image on a latent image carrier, wherein a thin layer of toner is formed on the surface of the toner carrier according to claim 1, and the thin layer is supplied to the latent image carrier. A developing device for developing the developing device. 12. At least a latent image carrier and an image carrier according to claim 1.
2. A process cartridge, wherein the developing device according to claim 1 is integrally formed as a cartridge and is detachable from an image forming apparatus main body. In the developing device, the toner carrier carries a one-component toner from a toner storage container. A process cartridge in which the one-component toner is carried and transported by a developing unit. 13. The method for producing a toner carrier according to claim 1, wherein at least the thermoplastic elastomer (A) and the crosslinkable elastomer (B) are used.
And a step of kneading one or more additives selected from the group consisting of a crosslinking agent, a softening agent and a compatibilizer, and crosslinking is possible under a shearing force in a state where the thermoplastic elastomer (A) is molten. A step of subjecting the elastomer (B) to a cross-linking reaction to form the conductive elastic layer. 14. The method according to claim 13, wherein the conductive filler (C) is added after a crosslinking reaction of the crosslinkable elastomer (B).