JP3601660B2 - Toner carrier, method of manufacturing the same, and image forming apparatus - Google Patents

Description

【００２９】
〔注〕
ＣＭ８０００：東レ社製可溶性共重合ナイロン、重量％はメタノールとの合計量に対する値である。
ＣＢ：カーボンブラック、デグッサ社製 Ｐｒｉｎｔｅｘ３５
Ｍ６４０２：大日本インキ化学工業社製オイルフリーアルキッド樹脂
Ｌ１４５：大日本インキ化学工業社製メラミン樹脂
ＫＲ２１１：信越シリコーン社製シリコーン樹脂
Ｍ６４０２／Ｌ１４５／ＫＲ２１１の重量％は、これらの樹脂合計量とメチルエチルケトンとの合計に対する樹脂合計量の値である。
ＭＥＫ：メチルエチルケトン
【００３０】
【発明の効果】
本発明のトナー担持体は、長期的に使用しても白画像のかぶり、ハーフトーン画像のザラツキあるいは黒画像の濃淡ムラなどの発生がない耐久性に優れるものであって、各種画像形成装置のトナー担持体として好適に用いられる。
【図面の簡単な説明】
【図１】トナー担持体の一例を示す概略断面図である。
【図２】加圧現像方式による画像形成装置の一例を示す概要図である。
【図３】本発明のトナー担持体の一例を示す概略断面図である。
【符号の説明】
１：トナー担持体（現像ローラ）
２：シャフト
３：導電性弾性層
４：被覆層
４ａ：第１樹脂被覆層
４ｂ：第２樹脂被覆層
５：トナー塗布用ローラ
６：画像形成体（感光体）
７：トナー
８：成層ブレード
９：転写部
１０：クリーニング部
１１：クリーニングブレード[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a toner carrier, a method of manufacturing the same, and an image forming apparatus using the toner carrier. More specifically, the present invention relates to a toner carrier excellent in long-term durability and capable of forming a high-quality image, a method for efficiently manufacturing the toner carrier, and an image forming apparatus equipped with the toner carrier. is there.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, a one-component toner is supplied to an image forming body such as a photoconductor holding an electrostatic latent image, and the toner is attached to the latent image. A pressure development method is known as an image forming method for visualizing the image (US Pat. Nos. 3,515,2012 and 3,731,146). In this pressure development method, a toner carrier carrying toner is brought into contact with an image forming body (photoreceptor) holding an electrostatic latent image, and the toner is attached to the latent image of the image forming body. Therefore, the toner carrier needs to be formed of a conductive elastic body having conductivity and elasticity.
[0003]
FIG. 2 is a schematic diagram showing an example of an image forming apparatus using the pressure development method. In the pressure development method, as shown in FIG. A toner carrier (developing roller) 1 is disposed between a roller 5 and an image forming body (photoconductor) 6 holding an electrostatic latent image, and the toner carrier 1, the image forming body 6, and a toner applying roller The toner 5 is supplied to the surface of the toner carrier 1 by the toner application roller 5 by rotating the toner 5 in the direction of the arrow in the figure, and the toner is arranged into a uniform thin layer by the layering blade 8. Then, in this state, the toner formed in a thin layer adheres to the latent image of the image forming body 6 by rotating the toner carrier 1 while being in contact with the image forming body 6. The latent image is made visible.
In the drawing, reference numeral 9 denotes a transfer unit, which transfers a toner image to a recording medium such as paper. Reference numeral 10 denotes a cleaning unit, and the cleaning blade 11 removes toner remaining on the surface of the image forming body after transfer.
[0004]
In such an image forming apparatus using the pressure development method, the toner carrier 1 must rotate while maintaining a state in which the toner carrier 1 is in close contact with the image forming body 6, and therefore, is shown in the schematic cross-sectional view of FIG. Thus, an elastic rubber such as silicone rubber, NBR (acrylonitrile-butadiene copolymer rubber), EPDM (ethylene-propylene-diene copolymer rubber), polyurethane rubber, or the like is provided on the outer periphery of the shaft 2 made of a good conductive material such as a metal. It has a structure in which a conductive elastic layer 3 made of a conductive elastic body provided with conductivity by blending a conductive agent into a foam or the like is formed. Further, a coating made of a resin or the like is used to control the chargeability and adhesion of the toner 7 or to control the frictional force between the image forming body 6 and the layering blade 8 and to prevent the photosensitive member from being contaminated by the elastic body. The layer 4 is provided on the surface of the conductive elastic layer 3.
On the other hand, there is also proposed an image forming method for forming an image by directly flying toner carried on a toner carrier through a hole-shaped control electrode onto an image forming body made of paper such as paper or OHP paper. Have been. In addition, a thin layer of non-magnetic toner is carried on the surface of a sleeve-shaped toner carrier disposed in a non-contact state close to the image forming body (photoconductor), and the non-magnetic toner flies onto the photoconductor. A method of forming an image by developing the image is also proposed (JP-A-58-116559).
[0005]
In either case, the resin is placed on the toner carrier to control the chargeability and adhesion of the toner, or to reduce the frictional force with other members such as the photoconductor, the layered blade, and the control electrode. Is provided on the surface of the conductive elastic layer.
By the way, in order to obtain a bias voltage serving as a driving force for transferring the toner held on the toner carrier to the image forming body, the toner carrier has an overall resistance value of 10%. ⁶ -10 ¹¹ It is about Ω · cm. In many cases, the resistance of the conductive elastic layer is set to a low resistance and the resistance of the resin coating layer is set to a high resistance in order to easily adjust the resistance. At this time, the resistance of the resin coating layer is determined by incorporating conductive fine particles such as carbon and metal oxide into the resin.
However, as printers and the like are accelerated, fine images are required, and color images are formed, the demands for image formation become strict, and the problems that cannot be dealt with by the conventional toner carrier as described above appear. It has become. That is, if the number of printed sheets is increased by incorporating the toner carrier into the image forming apparatus and using it for a long period of time, image defects such as fog of a white image, roughness of a halftone image, and uneven shading of a black image occur. there were.
[0006]
[Problems to be solved by the invention]
Under such circumstances, the present invention provides a toner carrier having excellent durability, which does not generate fog of a white image, roughness of a halftone image, or uneven density of a black image even when used for a long time, and It is an object of the present invention to provide an image forming apparatus using the same.
[0007]
[Means for Solving the Problems]
The present inventors have intensively studied on a toner carrier having excellent long-term durability and capable of forming a high-quality image. In the process, if the toner is used for a long time, the coating layer on the surface of the toner carrier is worn out or toner filming occurs due to friction with the toner, the toner applying roller or the layering blade, and as a result, the toner It has been found that the surface properties of the body change, the toner charge amount decreases, and image defects such as fog of a white image, roughness of a halftone image, and unevenness of density of a black image occur.
The present inventors have further studied based on this finding, and as a result, provided a first resin coating layer having a specific resistance or less on the surface of the conductive elastic base material, The toner carrier provided with a second resin coating layer containing no fine particles and having a specific resistance not less than a certain value has excellent long-term durability and can form a high-quality image. It has been found that the coating layer and the second resin coating layer can be easily manufactured by forming them by a coating method using a specific solvent. The present invention has been completed based on such findings.
[0008]
That is, the present invention provides a toner carrier that forms a visible image by carrying a toner on the surface to form a thin film thereof, and supplying or supplying the toner to the surface of the image forming body in contact with or in proximity to the image forming body. In the above, the specific resistance is 10 on the surface of the conductive elastic substrate. ⁶ A first resin coating layer of Ω · cm or less is provided, and no conductive fine particles are contained thereon. ¹⁰ An object of the present invention is to provide a toner carrier provided with a second resin coating layer of Ω · cm or more, and an image forming apparatus equipped with the toner carrier.
Further, the toner carrier is a first resin coating layer coating solution using a poor solvent for the elastic body constituting the conductive elastic base material and a second solvent using a poor solvent for the resin constituting the first resin covering layer. (2) It can be manufactured by forming a first resin coating layer and a second resin coating layer on the surface of a conductive elastic substrate by a coating method using a coating liquid for a resin coating layer.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The conductive elastic base material as referred to in the present invention refers to a material provided with a conductive elastic layer outside a shaft or the like.
As shown in FIG. 3, the toner carrier of the present invention has a conductive elastic layer formed on the outside of a good conductive shaft or the like, and two resin coating layers formed on the surface thereof.
FIG. 3 is a schematic view showing an example of the toner carrier of the present invention, in which a conductive elastic layer 3 is provided on the outer periphery of a shaft 2, and a first resin is provided on the surface of the conductive elastic layer 3. This shows a structure in which a coating layer 4a and a second resin coating layer 4b are sequentially formed.
For the conductive elastic layer, an elastic material obtained by adding a conductive agent to an appropriate rubber-like elastic body to impart conductivity is used. Here, the rubber-like elastic body is not particularly limited, and may be arbitrarily selected from those conventionally used in a toner carrier. Examples of the rubbery elastic body include nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, silicone rubber, urethane rubber, acrylic rubber, chloroprene rubber, butyl rubber, epichloro rubber. And hydrin rubber. These may be used alone or in combination of two or more. Among them, nitrile rubber, urethane rubber, epichlorohydrin rubber, ethylene propylene rubber, and ethylene propylene diene rubber are particularly preferable.
[0010]
In addition, as the conductive agent, an ionic conductive agent or an electronic conductive agent is used. Examples of the ionic conductive agent include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (eg, lauryltrimethylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium (eg, stearyltrimethylammonium), benzyltrimethylammonium, and a modified fatty acid dimethylethylammonium. Ammonium salts such as perchlorates, chlorates, hydrochlorides, bromates, iodates, borofluorides, sulfates, ethyl sulfates, carboxylates and sulfonates, lithium and sodium Perchlorates, chlorates, hydrochlorides, bromates, iodates, borofluorides, trifluoromethyl sulfates of alkali metals and alkaline earth metals such as potassium, potassium, calcium and magnesium Salts, and sulfonic acid salts.
Examples of the electronic conductive agent include conductive carbon such as Ketjen black and acetylene black; carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT and MT; and ink for oxidized ink. Carbon, pyrolytic carbon, graphite; conductive metal oxides such as tin oxide, titanium oxide, and zinc oxide; and metals such as nickel and copper.
[0011]
These conductive agents may be used alone or in combination of two or more. The amount of addition is not particularly limited, but in the case of the ionic conductive agent, usually 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the rubber-like elastic body. Selected by range. On the other hand, in the case of the electronic conductive agent, it is selected in the range of 1 to 50 parts by weight, preferably 5 to 40 parts by weight, based on 100 parts by weight of the rubber-like elastic body. Thereby, the resistance value of the conductive elastic layer is set to 10 ³ -10 ¹⁰ It is preferable to adjust it to the range of Ω · cm, ⁴ -10 ⁸ It is preferable to adjust the range to Ω · cm. Note that, in addition to the conductive agent, other rubber additives such as a known filler and a crosslinking agent can be appropriately added to the conductive elastic layer as needed.
[0012]
This conductive elastic layer preferably has a hardness of 60 ° or less in JIS-A, and particularly preferably in the range of 25 to 55 °. If the hardness exceeds 60 °, the toner carrier becomes hard, and the contact area with the photoreceptor or the like becomes small, and there is a possibility that good image formation cannot be performed. Further, the toner is damaged, and the toner adheres to the photoreceptor and the layered blade, and the image is likely to be defective. Conversely, if the hardness is too low, the friction with the photoreceptor or the stratification blade increases, and image defects such as jitter may occur. In addition, since the conductive elastic layer is used in contact with a photoreceptor, a layered blade, or the like, the compression set is preferably small, specifically, 20% or less, particularly preferably 10% or less. In particular, polyurethane rubber is advantageous because compression set can be designed to be small.
Further, the surface roughness of this conductive elastic layer is preferably 15 μmRz or less, particularly preferably 3 to 10 μmRz in terms of JIS 10-point average roughness. If the average roughness exceeds 15 μm Rz, it is necessary to form a thick surface layer of the toner carrier, and as a result, the surface of the toner carrier becomes hard and damages the toner, causing the toner to adhere to the photoreceptor and the layering blade. Is generated and causes image defects, which is not preferable. On the other hand, if Rz is too small, when the surface layer is formed, Rz on the surface of the toner carrier becomes too small, the amount of toner carried becomes small, and the image density may decrease, which is not preferable.
[0013]
In the toner carrier of the present invention, a conductive material is used to control the chargeability and adhesion of the toner, or to reduce the frictional force between the photoconductor and a layered blade and to prevent the photoconductor from being contaminated by an elastic body. A first resin coating layer and a second resin coating layer are sequentially provided on the surface of the elastic base material, that is, on the surface of the conductive elastic layer.
Here, for the first resin coating layer, it is preferable to use a resin that dissolves in a poor solvent for the rubber-like elastic body constituting the conductive elastic layer. If the coating liquid for the first resin coating layer prepared using the poor solvent is applied on the conductive elastic layer as described later, the conductive elastic layer does not swell, so that the coating is formed when dried. No inconvenience such as myself occurs. As such a resin, for example, an alcohol-soluble copolymerized polyamide, a water-soluble acrylic resin, a water-soluble butyral resin and the like are preferably exemplified, and among these, the alcohol-soluble copolymerized polyamide is particularly preferable.
This first resin coating layer has a specific resistance of 10 ⁶ Ω · cm or less, and preferably 10 ³ -10 ⁶ Ω · cm. Therefore, the coating layer usually contains a conductive agent. Examples of the conductive agent include the same as those exemplified in the description of the conductive elastic layer.
[0014]
The method for forming the first resin coating layer is not particularly limited, but usually, a resin and other additives are dissolved or dispersed in a solvent to prepare a coating liquid, and the coating liquid is dipped, The first resin coating layer is formed by coating the conductive elastic layer on the conductive elastic layer by a coater method, a doctor blade method, a spray method, or the like, and drying and curing the same at room temperature or at a temperature of about 50 to 170 ° C. Its thickness is usually in the range of about 3 to 30 μm, preferably 5 to 20 μm.
On the other hand, in the second resin coating layer, it is preferable to use a resin that dissolves in a poor solvent for the resin constituting the first resin coating layer. By preparing a coating solution for the second resin coating layer using this poor solvent and applying it on the first resin coating layer as described later, the solvent used for forming the first resin coating layer is completely removed. The coating can be performed in a state where it remains without being dried, that is, in a so-called air-dried state, which is preferable from the viewpoint of improving the production efficiency.
[0015]
Examples of the resin used in the second resin coating layer include ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone, aromatic hydrocarbon solvents such as toluene and xylene, aliphatic hydrocarbon solvents such as hexane, and oils such as cyclohexane. Dissolves in cyclic hydrocarbon solvents, ester solvents such as ethyl acetate, ether solvents such as isopropyl ether and tetrahydrofuran, amide solvents such as dimethyl sulfoamide, and halogenated hydrocarbon solvents such as chloroform and dichloroethane. Resins can be mentioned. Examples of such resins include polyester resin, polyether resin, fluorine resin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, alkyd resin, phenol resin, melamine resin, urea resin, Examples include silicone resins, polyvinyl butyral resins, and the like, and blends thereof. Among these, a fluororesin, a polyamide resin, an acrylic urethane resin, an alkyd resin, a phenol resin, a melamine resin, a silicone resin and a blend thereof are preferable. In particular, an alkyd resin, a phenol resin, a melamine resin and a blend thereof are preferable. It is preferable from the viewpoints of charging ability of the toner, non-staining property to the toner, reduction of frictional force with other members, non-staining property to the photoconductor, and the like.
[0016]
The second resin coating layer in the present invention is preferably made of a cross-linked resin, and the soluble portion of the resin before cross-linking when extracted with a good solvent, such as methyl ethyl ketone or toluene, is 30% by weight or less, particularly 10% by weight. It is preferred that: If the soluble portion exceeds 30% by weight, it has a relatively low molecular weight and contains a large amount of uncured components, resulting in insufficient durability, contamination of the photoreceptor, contamination and aggregation of the toner, wear of the coating layer, increase in the friction coefficient, etc. This is not preferred.
Note that the amount of the solvent-soluble portion can be calculated according to the following equation.
Solvent soluble part amount (% by weight) = [(weight before solvent extraction−weight after solvent extraction) / weight before solvent extraction] × 100
[0017]
The above-mentioned cross-linked resin can be cross-linked by a reaction with a cross-linking resin or a cross-linking agent or another cross-linking resin which can be self-cross-linked by, for example, heat, catalyst, air (oxygen), moisture (water), electron beam or the like. It is obtained by subjecting a crosslinkable resin to a crosslinking treatment. Here, examples of the crosslinkable resin include a hydroxyl group, a carboxyl group, an acid anhydride group, an amino group, an imino group, an isocyanate group, a methylol group, an alkoxymethyl group, an aldehyde group, a mercapto group, an epoxy group, and an unsaturated group. Resins having a reactive group (crosslinkable group), specifically, polyester resin, polyether resin, fluororesin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, alkyd resin, phenol resin, Melamine resin, urea resin, silicone resin, polyvinyl butyral resin and the like can be mentioned. These may be used alone or in combination of two or more.
Among these, a fluororesin, a polyamide resin, an acrylic urethane resin, an alkyd resin, a phenol resin, a melamine resin, a silicone resin and a blend thereof are preferable. In particular, an alkyd resin, a phenol resin, a melamine resin and a blend thereof are preferable. It is preferable from the viewpoints of charging ability of the toner, non-staining property to the toner, reduction of frictional force with other members, non-staining property to the photoconductor, and the like.
[0018]
Examples of the catalyst include radical catalysts such as peroxides and azo compounds, acid catalysts, basic catalysts, and alkali catalysts, and these are appropriately selected according to the type of the crosslinkable resin.
Examples of the crosslinking agent include reactive groups such as a hydroxyl group, a carboxyl group, an acid anhydride group, an amino group, an imino group, an isocyanate group, a methylol group, an alkoxymethyl group, an aldehyde group, a mercapto group, an epoxy group, and an unsaturated group. Compounds having a molecular weight of about 1,000 or less having two or more in one molecule, preferably compounds having a molecular weight of 500 or less, specifically, polyol compounds, polyisocyanate compounds, polyaldehyde compounds, polyamine compounds, polyepoxy compounds, and the like. Is appropriately selected according to the type of the crosslinkable resin.
In the present invention, the second resin coating layer does not contain conductive fine particles and has a specific resistance of 10%. ¹⁰ Ω · cm or more, preferably 10 ¹⁰ -10 ¹⁶ Ω · cm.
[0019]
Various additives such as a charge control agent, a lubricant, and other resins can be added to the second resin coating layer for the purpose of improving the chargeability of the toner and reducing the frictional force with other members.
The method for forming the second resin coating layer is not particularly limited, but usually, a coating solution is prepared by dissolving or dispersing a crosslinkable resin, a crosslinking agent, and other additives in a solvent. Is applied on the first resin coating layer by a dip method, a roll coater method, a doctor blade method, a spray method, or the like, dried at room temperature or at a temperature of about 50 to 170 ° C., and cured by crosslinking to form a second resin coating layer. To form Its thickness is usually in the range of about 1 to 20 μm, preferably 3 to 10 μm.
If the thickness of the second resin coating layer is less than 1 μm, local discharge may occur, and a horizontal white line may be easily generated in the image. If the thickness exceeds 20 μm, the toner carrier becomes hard and damages the toner. As a result, toner adheres to the photoreceptor or the layering blade, which causes image defects.
The resistance value of the toner carrier of the present invention is usually 10 ⁴ -10 ¹⁰ Ω · cm, preferably 10 ⁴ -10 ⁸ Ω · cm.
[0020]
Further, the surface roughness of the toner carrier, that is, the surface roughness of the second resin coating layer, is preferably 10 μmRz or less, particularly 1 to 8 μmRz in terms of JIS 10-point average roughness. If it exceeds 10 μmRz, the amount of charge of the toner becomes small, and a reversely charged toner is generated, which causes image fogging. If Rz is too small, the amount of toner carried is reduced, and the image density is undesirably reduced.
The present invention also provides an image forming apparatus equipped with the toner carrier.
The type of the image forming apparatus of the present invention is not particularly limited. For example, (1) a toner carrier carrying a toner is brought into contact with an image carrier (photoconductor) holding an electrostatic latent image, and A pressure development method in which an image is formed by adhering to a latent image of a formed body; (2) a toner carried on a toner carrier on an image formed body made of paper sheets via a control electrode in the form of a hole; A method of forming an image by direct flight, (3) a non-magnetic layer formed on a surface of a sleeve-like toner carrier provided in a non-contact state in close proximity to an image forming body (photoreceptor) Any method may be used, such as a method in which a toner is carried, and the toner is caused to fly on a photoreceptor to perform development to form an image. As an example of the image forming apparatus of the present invention, the above-described apparatus of the pressure development type shown in FIG. 2 can be mentioned.
[0021]
【Example】
Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.
The characteristics of the toner carriers prepared in Examples and Comparative Examples were determined according to the following procedure.
(1) Surface layer thickness
The vertical section of the toner carrier was observed and measured with a scanning electron microscope.
[0022]
(2) Solvent-soluble portion of second resin coating layer
Separately from the toner carrier, a glass plate was prepared, and the coating liquid used for forming the second resin coating layer of each toner carrier was applied on the glass plate, and the same conditions as in the preparation of each toner carrier were applied. The coating was heated and crosslinked and cured. Thereafter, the entire glass plate was immersed in methyl ethyl ketone for 24 hours at 25 ° C., dried, the weight of the coating film before and after immersion was measured, the solvent-soluble part amount was calculated from the following equation, and the amount of the solvent-soluble part was calculated. 2 The amount of the solvent-soluble portion of the resin coating layer was defined as the amount.
Solvent soluble part amount (% by weight) = [(weight before solvent extraction−weight after solvent extraction) / weight before solvent extraction] × 100
(3) Volume resistivity value of coating layer
Prepare a copper plate, apply the coating solution on the copper plate using the coating solution used to form the coating layer of each toner carrier, heat the coating film under the same conditions as each toner carrier, and crosslink. Curing was performed. Thereafter, the resistance between the copper plate and the measurement electrode was measured to obtain the specific resistance of the coating layer.
[0023]
(4) Resistance of toner carrier
Each toner carrier was pressed against a copper plate with a load of 500 g applied to both sides thereof, and the resistance was measured by applying a voltage of 100 V using a resistivity meter R8340A (manufactured by Advantest).
(5) Toner transport amount
Each toner carrier is used as a developing roller in the developing unit of the image forming apparatus shown in FIG. 2 and rotated at a peripheral speed of 50 mm / sec to form a uniform thin toner layer on the surface of the developing roller (toner carrier). Then, the thin toner layer was suctioned to measure the weight, and the value obtained by dividing the weight by the suctioned area was defined as the toner transport amount.
(6) Toner charge amount
Each toner carrier is used as a developing roller in the developing unit of the image forming apparatus shown in FIG. 2 and rotated at a peripheral speed of 50 mm / sec to form a uniform thin toner layer on the surface of the developing roller (toner carrier). Then, the thin toner layer was sucked and introduced into the Faraday gauge, and the charge amount was measured.
[0024]
(7) Image evaluation
Each toner carrier was used as a developing roller in the developing unit of the image forming apparatus shown in FIG. 2, and a developing bias voltage of 400 V and a blade bias voltage of 600 V were used. An image was formed by reversal development while rotating at a peripheral speed of 60 mm / sec, and image evaluation on a white background, a halftone image, and a black background image was performed before and after a 3,000-sheet durability test.
Evaluation criteria
<Fogging>
○: No fogging
×: Fogging on white background
<Black image>
：: Normal concentration
×: low concentration
[0025]
Example 1
2.85 parts by weight of acetylene black was mixed with 100 parts by weight of a polyisoprene polyol having a molecular weight of 2,500 (OH value: 47.1 mgKOH / g), and the mixture was mixed using a mixer to prepare a polyol composition. After stirring and defoaming the polyol composition under reduced pressure, 13.33 parts by weight of crude MDI (crude meta-xylylene diisocyanate) (NCO wt%; 31.7) was added, and the mixture was stirred for 2 minutes. 0.001 part by weight of tindilaurate was added and stirred for 3 minutes. Next, this was cast in a mold in which a shaft was placed and heated to 90 ° C. in advance, and cured at 90 ° C. for 12 hours to form a conductive elastic body on the outer periphery of the metal shaft to obtain a roller. The surface of the obtained roller was polished to adjust the surface to a JIS 10-point average roughness of 10 μmRz.
Next, a soluble copolymer nylon (CM8000 manufactured by Toray Industries, Inc.) was dissolved in methanol to a concentration of 10% by weight, carbon black (Printex 35 manufactured by Degussa) was added to the resin at 50% by weight, and glass beads were further added. After that, the mixture was shaken with a paint shaker for 5 hours to prepare a coating liquid. The roller was immersed in the coating solution, pulled up, and air-dried for 1 hour to form a first resin layer. Next, an oil-free alkyd resin (M6402 manufactured by Dainippon Ink and Chemicals, Inc.), a melamine resin (145 manufactured by Dainippon Ink and Chemicals, Inc.) and a silicone oil (KR211 manufactured by Shin-Etsu Silicone Co., Ltd.) were added in methyl ethyl ketone at a resin weight ratio of 56:20. : 24, and dissolved so that the total resin concentration became 20% by weight to prepare a coating solution. The roller provided with the first resin layer was immersed in the coating liquid and pulled up to form a second resin layer. At that time, no elution into the first resin layer was confirmed. Next, this was heated at 110 ° C. for 4 hours to obtain a toner carrier having a three-layer structure shown in FIG. 3 having a crosslinked and cured second resin layer.
[0026]
This toner carrier was placed on a commercially available LBP (2200X manufactured by NEC), and the initial image, the amount of transferred toner, and the amount of charged toner were measured. Next, an image sample of 5% print density was subjected to a 3,000-sheet passing test. After the printing, the image was evaluated again, and the toner transport amount and the toner charge amount were measured. The obtained image was good both in the initial stage and after the endurance, and almost no decrease in the toner conveyance amount and the toner charge amount was observed.
The results are shown in Table 1.
Comparative Example 1
A toner carrier was manufactured in the same manner as in Example 1, except that the first resin layer was not provided and the resin concentration of the second resin layer forming coating liquid was 35% by weight. The results are shown in Table 1.
Since the resistance value of the toner carrier became extremely high, a predetermined developing bias could not be secured, and in the initial image, black density was insufficient and white background fogging occurred on the front surface, resulting in image failure.
[0027]
Comparative Example 2
A toner carrier was manufactured in the same manner as in Comparative Example 1, except that carbon black was added to the second resin layer forming coating liquid so as to be 25% by weight of the resin. The results are shown in Table 1.
Although the initial image and the initial charge amount were good, the toner charge amount after the printing paper-passing test similar to that in Example 1 was low, and the image after the endurance had much white background fog.
Comparative Example 3
A toner carrier was manufactured in the same manner as in Example 1 except that the second resin layer was not provided. The results are shown in Table 1.
The initial charge amount was rather low, and the toner charge amount was remarkably reduced by a printing paper-passing test, and the image after durability had a lot of white background fog.
[0028]
[Table 1]

[0029]
〔note〕
CM8000: soluble copolymer nylon manufactured by Toray Co., Ltd.,% by weight is based on the total amount with methanol.
CB: Carbon black, Printex 35 manufactured by Degussa
M6402: Oil-free alkyd resin manufactured by Dainippon Ink and Chemicals, Inc.
L145: Melamine resin manufactured by Dainippon Ink and Chemicals, Inc.
KR211: Silicone resin manufactured by Shin-Etsu Silicone
The weight% of M6402 / L145 / KR211 is a value of the total amount of the resin with respect to the total of the total amount of these resins and methyl ethyl ketone.
MEK: Methyl ethyl ketone
[0030]
【The invention's effect】
The toner carrier of the present invention is excellent in durability without generation of fog of a white image, roughness of a halftone image or unevenness of density of a black image even when used for a long period of time. It is suitably used as a toner carrier.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view illustrating an example of a toner carrier.
FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus using a pressure development method.
FIG. 3 is a schematic sectional view showing an example of the toner carrier of the present invention.
[Explanation of symbols]
1: toner carrier (developing roller)
2: Shaft
3: Conductive elastic layer
4: coating layer
4a: first resin coating layer
4b: second resin coating layer
5: Roller for toner application
6: Image forming body (photoreceptor)
7: Toner
8: stratified blade
9: transfer unit
10: Cleaning unit
11: Cleaning blade

Claims (7)

In the toner carrier that forms a visible image by supplying toner to the surface of the image forming body by contacting or approaching the image forming body by forming a thin film by carrying the toner on the surface, the conductive elastic base A first resin coating layer having a specific resistance of 10 ⁶ Ω · cm or less is provided on the surface of the material, and a second resin coating layer containing no conductive fine particles and having a specific resistance of 10 ¹⁰ Ω · cm or more is provided thereon. A toner carrier, wherein the toner carrier is provided. 2. The toner carrier according to claim 1, wherein the resin constituting the first resin coating layer is a resin soluble in a poor solvent for the elastic body constituting the conductive elastic substrate. 3. The toner carrier according to claim 1, wherein the resin constituting the first resin coating layer is an alcohol-soluble copolymerized polyamide resin. 4. The toner carrier according to claim 1, wherein the resin constituting the second resin coating layer is a resin soluble in a poor solvent for the resin constituting the first resin coating layer. 5. The toner carrier according to any one of claims 1 to 4, wherein the second resin coating layer is formed of a crosslinked resin, and has a soluble portion of 30% by weight or less when extracted with a good solvent of the resin before crosslinking. body. A first resin coating layer and a second resin coating layer are sequentially formed by applying a coating liquid on the surface of the conductive elastic base material, and a first resin coating layer coating liquid is used for manufacturing a toner carrier. Is characterized by using a poor solvent for the elastic material constituting the conductive elastic base material and using a poor solvent for the resin constituting the first resin coating layer as the coating liquid for the second resin coating layer. A method for producing a toner carrier according to any one of claims 1 to 5. An image forming apparatus having a toner carrying member for forming a visible image by forming a thin film by carrying a toner on the surface and supplying toner to the surface of the image forming material in contact with or close to the image forming body An image forming apparatus according to claim 1, wherein the toner carrier according to any one of claims 1 to 5 is used as the toner carrier.

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