JP2009151144A - Developing roller and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller excellent in fogging resistance and toner filming resistance, the developing roller reliably forming a good image, and to provide an image forming apparatus using the same. <P>SOLUTION: The developing roller is constituted so that a semiconductive elastic layer 2 is formed around a core bar 1 and further a surface resin layer 3 is formed on the elastic layer 2 directly or by way of an intermediate layer, wherein the elastic layer 2 includes urethane foam, and the surface resin layer 3 is formed from a resin composition comprising a urethane resin, a silicone-grafted acrylic resin and a perfluoroalkyl group-containing resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides an image forming apparatus having a developing mechanism for supplying a developer to a latent image holding member carrying an electrostatic latent image to visualize the electrostatic latent image, and supplying the developer to the latent image holding member. The present invention relates to a developing roller used for image forming, and an image forming apparatus using the developing roller.

  For example, in an image forming apparatus such as an electrophotographic apparatus such as a printer or a copying machine, a developing operation for supplying a developer (toner) to a latent image holding member carrying an electrostatic latent image to visualize the electrostatic latent image is performed. Is called. In this case, a semiconductive elastic roller is generally used as a developing roller for supplying the developer.

  As this developing roller, a roller using a polyurethane foam as an elastic layer is known. In this case, since a foam having relatively fine bubbles is obtained, a polyurethane foam obtained by mechanical stirring foaming (mechanical floss method) is preferably used. Conventionally, a polyurethane resin paint is applied on the polyurethane foam elastic layer. Is applied to secure toner filming resistance, but this developing roller cannot always obtain sufficient toner chargeability. In order to obtain sufficient toner chargeability, it has been proposed to form a surface layer with a silicone resin (Patent Document 1).

  However, the silicone resin is inferior in dispersibility of the conductive agent carbon black, easily causes coating unevenness, and it is difficult to form a uniform coating film without unevenness, and the coating film unevenness may affect the image quality. It was.

  Further, in order to improve the problem of uneven coating and toner filming, it has been proposed to blend a low molecular weight graft acrylic resin as a urethane raw material (Patent Document 2). However, in this case, there arises a problem that the fog resistance deteriorates.

Japanese Patent Laid-Open No. 11-65268 JP 2004-295095 A

  The present invention has been made in view of the above circumstances, and provides a developing roller excellent in fog resistance and toner filming resistance and capable of reliably obtaining a good image, and an image forming apparatus using the developing roller. The purpose is to do.

  As a result of intensive studies to achieve the above object, the present inventor formed a semiconductive elastic layer with urethane foam around the core metal, and further, directly or through an intermediate layer on the outer periphery of the elastic layer. When the surface resin layer is formed to obtain a developing roller, the surface resin layer is formed of a resin composition containing a urethane resin, a silicone graft acrylic resin, and a perfluoroalkyl group-containing resin. The present invention has been completed by finding that a developing roller having excellent fog and toner filming resistance and capable of reliably obtaining a good image can be obtained.

  Accordingly, the present invention provides a developing roller in which a semiconductive elastic layer is formed around a cored bar, and a surface resin layer is formed directly or via an intermediate layer on the elastic layer. Provided is a developing roller made of a urethane foam, wherein the surface resin layer is formed of a resin composition containing a urethane resin, a silicone graft acrylic resin, and a perfluoroalkyl group-containing resin. To do.

  The present invention also provides an image forming apparatus provided with a developing mechanism that supplies a developer to a latent image holding member carrying an electrostatic latent image to visualize the electrostatic latent image, and uses the developer as a latent image holding member. The present invention provides an image forming apparatus using the developing roller of the present invention as the developing roller to be supplied.

  The developing roller of the present invention is excellent in fog resistance and toner filming resistance, and according to the image forming apparatus using this developing roller, a good image can be stably obtained over a long period of time. .

Hereinafter, the present invention will be described in more detail.
For example, as shown in FIG. 1, the developing roller of the present invention includes a cored bar 1, an elastic layer 2 formed around the cored bar 1, and a surface resin layer 3 formed on the outer periphery of the elastic layer 2. In the present invention, the surface resin layer 3 is formed of a resin composition containing a urethane resin, a silicone graft acrylic resin, and a perfluoroalkyl group-containing resin.

  The elastic layer 2 is formed of a polyurethane foam. In this case, the composition of the polyurethane foam is not particularly limited, and may be formed by foam-molding a known polyurethane raw material containing a polyol component and an isocyanate component, and particularly a polyurethane containing a polyol component and an isocyanate component. A polyurethane foam formed by foaming the raw material by mechanical stirring is preferably used.

  In this case, the polyol component is not particularly limited, and any known polyol as a raw material polyol for producing urethane foam can be used. For example, a polyether polyol, a polyester polyol, or a polyester polyether polyol can be used for a roller. Although it can select suitably according to this invention, in this invention, especially polyester polyol and polyether polyol are used preferably, and any one or both of these can be mixed and used.

  More specifically, as polyether polyol, polyether polyol obtained by addition polymerization of alkylene oxide such as polyethylene oxide or propylene oxide to glycerin, etc., polyether polyol obtained by ring-opening polymerization of tetrahydrofuran, Examples thereof include polyether polyols such as polytetramethylene glycol, ethylene glycol, propanediol, and butanediol.

  Polyester polyols include condensation polyester polyols obtained by condensation of dicarboxylic acids with diols, triols, etc., lactone polyester polyols obtained by ring-opening polymerization of lactones based on diols and triols, and ends of polyether polyols. A polyol such as an ester-modified polyol obtained by ester-modifying lactone with lactone is exemplified.

  These polyols are not particularly limited, but preferably have a number average molecular weight of 500 to 5000, particularly 1000 to 3000, a hydroxyl value of 22 to 224 mgKOH, particularly 37 to 112 mgKOH, and the number of functional groups. It is preferable that it is 2-3, and also about polyether polyol, it is preferable that ethylene oxide content is 10-50%.

  Next, the isocyanate is not particularly limited, and can be appropriately selected from conventionally known various isocyanate compounds. Specific examples include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), modified TDI, modified MDI, modified HDI and the like, and in particular, modified TDI, modified MDI, and modified HDI are preferably used. It is done. In this case, the type of the modified product is not particularly limited, but a polyol-modified product is preferable. Among them, a polyol-modified TDI is particularly preferably used in combination with the polyether polyol or polyester polyol. These isocyanates are not particularly limited, but the NCO content is preferably 1 to 25%, particularly 4 to 10%.

  Usually, a conductive agent is blended in the polyurethane foam of the elastic layer 2 to impart or adjust conductivity. As the conductive agent, a known ionic conductive agent or electronic conductive agent can be used, and further, an ionic conductive agent and an electronic conductive agent can be used in combination.

  Examples of the ionic conductive agent include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (for example, lauryltrimethylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium (for example, stearyltrimethylammonium), benzyltrimethylammonium, and a modified fatty acid dimethylethylammonium. Perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, ethyl sulfate, carboxylate, sulfonate, etc. ammonium salt, lithium, sodium Perchlorates, chlorates, hydrochlorides, bromates, iodates, borofluorides, trifluoromethyls of alkali metals and alkaline earth metals such as potassium, calcium and magnesium Sulfates, such as sulfonate are exemplified.

  In addition, as the electronic conductive agent, conductive carbon such as ketjen black and acetylene black; rubber carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; carbon for ink subjected to oxidation treatment, Examples include pyrolytic carbon, natural graphite, and artificial graphite; conductive metal oxides such as tin oxide, titanium oxide, and zinc oxide; metals such as nickel, copper, silver, and germanium.

  Furthermore, in the polyurethane foam constituting the elastic layer of the conductive roller of the present invention, in addition to the polyol component, isocyanate component and conductive agent, a foam stabilizer, a cross-linking agent, a surfactant, a catalyst are optionally used. An appropriate amount of known additives such as these can be added.

  Examples of the foam stabilizer include polydimethylsiloxane-polyethylene oxide copolymer, polydimethylsiloxane-polypropylene oxide copolymer, polydimethylsiloxane-polyethylene adipate copolymer, and the like.

  Examples of the catalyst include dibutyltin dilaurate, dibutyltin diacetate, stannous octoate, dibutyltin marker tide, dibutyltin thiocarboxylate, dibutyltin dimalenate, dioctyltin marker peptide, dioctyltin thiocarboxylate as organometallic catalysts. , Phenylmercury, silver propionate, tin octenoate, amine catalyst triethylamine, N, N, N ′, N′-tetramethylethylenediamine, triethylenediamine, N-methylmorpholine, dimethylaminoethanol, bis (2-dimethylaminoethyl) ) Ether, 1,8-diazabicyclo (5,4,0) -undecene-7 and the like are preferably used. These catalysts may be used alone or in combination of two or more.

  The elastic layer 2 is prepared by mixing the isocyanate component, the polyol component, and a conductive agent added as necessary, and the additive, mechanically agitating and foaming, and casting into a mold in which a core metal is set, and thermosetting. By doing so, it can be formed around the cored bar 1.

  Next, the surface resin layer 3 is formed of a resin composition containing a urethane resin, a silicone graft acrylic resin, and a perfluoroalkyl group-containing resin.

  Here, the urethane resin can be obtained by reacting a polyol component with an isocyanate curing agent. In this case, examples of the polyol component include lactone-modified polyols, polyester polyols, polyether polyols, and the like, and one or more of these can be used. Among them, a lactone-modified polyol is particularly preferably used.

  On the other hand, as the isocyanate curing agent, known polyisocyanates can be used. Specifically, commercially available products such as Coronate HX and Coronate L manufactured by Nippon Polyurethane; Takenate D140N (IPDI skeleton) manufactured by Mitsui Chemicals Polyurethane. It is preferable to use an aliphatic isocyanate from the standpoint that the product can be suitably used, and that it does not deteriorate.

  The blending ratio of the isocyanate curing agent is appropriately set according to the type of the polyol component, the type of the isocyanate curing agent, and the like, and is not particularly limited, but is usually 20 parts per 100 parts by mass of the polyol component. It is preferable to set it as -80 mass parts, especially 30-70 mass parts.

  Next, the silicone-grafted acrylic resin is a silicone-modified polymer in which an acrylic polymer such as polymethyl methacrylate is grafted with a silicone such as polydimethylsiloxane having an amino group, a hydroxyl group, or a methacryloxy group at one or both terminal functional groups. These are acrylic resins, and one or more of these can be used.

  The molecular weight of the silicone graft acrylic resin is not particularly limited, but is preferably 10,000 to 100,000 in terms of number average molecular weight. If the number average molecular weight is less than 10,000, the unreacted silicone graft acrylic resin has a high temperature. Bleed-out may occur in a high humidity environment (for example, 50 ° C., 95% RH). On the other hand, if it exceeds 100,000, the elastic modulus of the surface resin layer 3 is increased, which causes toner damage and results in an image during durability. May cause inconvenience such as development streaks.

  The blending ratio of the silicone graft acrylic resin is not particularly limited, but it is usually preferably 5 to 30 parts by mass, particularly 10 to 20 parts by mass with respect to 100 parts by mass of the urethane resin. If the blending ratio of the silicone graft acrylic resin is less than 5 parts by mass, slipping performance and wear performance may be deteriorated, resulting in inconveniences such as filming in which the toner adheres to the developing roller. On the other hand, it exceeds 30 parts by mass. In some cases, the elastic modulus of the surface resin layer 3 becomes high and toner damage may occur, and unreacted silicone may bleed out and contaminate the photoreceptor.

  Examples of the perfluoroalkyl group-containing resin include “Megahook F493” (anionic, phosphate ester), “Megahook F450” (cationic, triammonium salt), and “Megahook F470” manufactured by Dainippon Ink and Chemicals, Inc. (Nonionic), perfluoroalkyl-containing resins such as “Megahook F-480SF” (nonionic and lipophilic group-containing oligomers), and perfluoroalkyl such as Defensers TR310, TR330, and TR301B manufactured by Dainippon Ink & Chemicals, Inc. Examples thereof include one or two or more of these, and the perfluoroalkyl group-containing acrylic resin is preferably used.

  The blending ratio of the perfluoroalkyl group-containing resin is not particularly limited, but is usually preferably 5 to 50 parts by mass, particularly 10 to 30 parts by mass with respect to 100 parts by mass of the urethane resin. . When the blending ratio of the perfluoroalkyl group-containing resin is less than 5 parts by mass, it may be difficult to obtain the effect. On the other hand, when it exceeds 50 parts by mass, the elastic modulus of the surface resin layer 3 increases. This may cause toner damage.

  In addition to the urethane resin, silicone graft acrylic resin and perfluoroalkyl group-containing resin, a known additive blended in the surface resin layer of the developing roller is appropriately blended in the surface resin layer 3 as necessary. For example, the same conductive agent and resin particles as those exemplified for the elastic layer can be blended as necessary.

The resin particles can be appropriately selected according to the type of the urethane resin, silicone-grafted acrylic resin, perfluoroalkyl group-containing resin, the thickness of the surface resin layer, etc., for example, urethane resin particles, acrylic resin particles, silicone Resin particles, silica particles, polyamide resin particles, nylon resin particles, and the like are exemplified, and one or more of these can be used. Further, the shape, size, particle size distribution, etc. of the particles are appropriately selected and are not particularly limited. Usually, spherical, square and needle-shaped particles are preferably used, and the particle size is D ₅₀ = 1. ˜50 μm, in particular D ₅₀ = 5-20 is preferred. The surface roughness of the roller can be adjusted by dispersing and blending these resin particles in the surface resin layer 3.

  The surface resin layer 3 is not particularly limited, but the surface static friction coefficient (JIS K7125) is preferably 0.1 to 0.6 μs, particularly preferably 0.2 to 0.5 μs. If it is too large, there may be a problem of so-called filming in which toner adheres. On the other hand, if it is too small, charging of the toner becomes difficult to control, and inconvenience such as fogging may occur. The static friction coefficient can be easily measured using a known measuring instrument such as “Tribogear μs Type 94i” manufactured by HEIDON.

  The thickness of the surface resin layer 3 is not particularly limited, but is usually 3 to 50 μm, particularly preferably 5 to 30 μm. In this case, the surface resin layer 3 is usually formed directly on the elastic layer 2, but if necessary, one or more intermediate layers are formed on the elastic layer 3, and this intermediate layer is formed. It can also be formed on the roller surface. In this case, the intermediate layer can be formed using a known resin such as a urethane resin, a urethane acrylic resin, a fluororesin, a silicone resin, or an acrylic resin.

  The surface resin layer 3 and the intermediate layer are formed by dissolving and dispersing the resin components and additives in a solvent such as methyl ethyl ketone, methyl isobutyl ketone, toluene, ethyl acetate, and methylcyclohexane to prepare a resin paint. What is necessary is just to apply on an elastic layer by well-known methods, such as a dipping, a spray, and a roll coater. Further, the intermediate layer can also be formed using a water-based resin, and thus can be configured in consideration of the environment. In this case, as the water-based resin, any of a fluororesin, an acrylic resin, a urethane resin, and the like may be used, but a urethane resin is also preferably used from the viewpoint of the resilience performance.

  The developing roller of the present invention is an image forming apparatus provided with a developing mechanism that supplies a developer to a latent image holding member carrying an electrostatic latent image and visualizes the electrostatic latent image, and carries the developer. It is used as a developing roller that supplies the latent image holding member. An example of such an image forming apparatus is an apparatus having the configuration shown in FIG.

  In other words, this apparatus is disposed in a state where the developing roller 5 is in contact with or close to the photosensitive drum (latent image holding member) 6 and is further disposed in a state in which the toner conveying roller 4 is in contact with the developing roller 5. Then, by rotating the photosensitive drum 6, the developing roller 5, and the toner transport roller 4 in the direction of the arrows in the figure, the toner t is transported from the toner reservoir in the toner cassette by the toner transport roller 4, and the developing roller 5 The toner t is adjusted to a uniform thin layer by the stratified blade 7 and the developing roller 5 rotates in this state in contact with or close to the photosensitive drum 6, thereby forming the toner formed in a thin layer. t is attached to the latent image on the photosensitive drum 6 from the developing roller 5, and the latent image is visualized to develop and form an image. In the figure, reference numeral 8 denotes a transfer unit, which transfers a toner image onto a recording medium 9 such as paper. Reference numeral 10 denotes a cleaning unit. After the transfer by the cleaning blade 11, the photosensitive drum 6 is transferred. The toner remaining on the surface is removed. In FIG. 2, charging means such as a charging roller are omitted.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not restrict | limited to the following Example.

[Example 1]
A polyurethane foam having the following composition was subjected to foam molding to form an elastic layer (thickness 4 mm) made of polyurethane foam on the outer periphery of the core metal (4 mmφ). At this time, A liquid in which polyol, foam stabilizer, ionic conductive agent, and catalyst are mixed and B liquid in which isocyanate and carbon black are mixed are prepared in advance, and these A liquid and B liquid are mechanically stirred and mixed. The polyurethane foam elastic layer having a density of 0.7 g / cm ³ was formed on the outer periphery of the core metal by foaming together and casting into a mold in which the core metal was set.
[Composition composition]
Polyol-modified tolylene diisocyanate 100 parts by mass (Asahi Glass Urethane Co., Ltd. prototype “BS 008” NCO content 6.7%)
Polyester polyol 24 parts by mass (Kuraray Co., Ltd. “Kuraray polyol F-510” hydroxyl value 336, functional group number 3)
Conductive carbon black 2 parts by mass Foam stabilizer (polydimethylsiloxane / polyethylene oxide copolymer) 5 parts by mass Ion conductive agent (sodium perchlorate) 0.3 parts by mass Catalyst (dibutyltin dilaurate) 0.2 parts by mass

  Next, with respect to 100 parts by mass of a lactone-modified polyol (“PCL220AL” manufactured by Daicel Chemical Industries, Ltd.), 5 parts by mass of a silicone graft acrylic resin (“Modi FS720” manufactured by NOF Corporation), a perfluoroalkyl group-containing acrylic resin (large 5 parts by mass of “Megahook F493” anionic, phosphate ester manufactured by Nippon Ink Chemical Industries, Ltd., 35 parts by mass of carbon black, 10 parts by mass of urethane particles (“Art Pearl C800” manufactured by Negami Kogyo Co., Ltd., average particle size 8.8 μm) Was then dispersed in 350 parts by mass of methyl ethyl ketone, and then 30 parts by mass of an isocyanate curing agent (“Coronate HX” manufactured by Nippon Polyurethane Co., Ltd.) was stirred for 30 minutes with a stirring motor to prepare a coating for the surface resin layer. A surface resin layer having a thickness of 10 μm is formed by coating on the elastic layer. To obtain a roller.

[Example 2]
Example 1 except that 5 parts by mass of “Megahook F450” (cationic, trimethylammonium salt) manufactured by Dainippon Ink & Chemicals, Inc. was used as the perfluoroalkyl group-containing acrylic resin instead of “Megahook F493”. Similarly, a coating for the surface resin layer was prepared, and this coating was applied on the same elastic layer as in Example 1 to form a surface resin layer having a thickness of 10 μm to obtain a developing roller.

[Example 3]
The blending ratio of the silicone graft acrylic resin is 5 parts by mass, and as a perfluoroalkyl group-containing acrylic resin, 10 parts by mass of “Megahook F470” (nonionic) manufactured by Dainippon Ink & Chemicals, Inc. instead of “Megahook F493” above. A coating for the surface resin layer is prepared in the same manner as in Example 1 except that is used, and this coating is applied onto the elastic layer similar to that in Example 1 to form a surface resin layer having a thickness of 10 μm. A developing roller was obtained.

[Example 4]
A urethane emulsion paint (“E-400” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was applied on the elastic layer formed in the same manner as in Example 1 to form an intermediate layer having a thickness of 70 μm. A surface resin layer similar to 1 was formed to obtain a developing roller.

[Comparative Example 1]
Surface resin layer in the same manner as in Example 1 except that a silicone resin (“SR2410” manufactured by Toray Dow Corning Co., Ltd.) was used instead of the lactone-modified polyol, the silicone graft acrylic resin, and the perfluoroalkyl group-containing acrylic resin. A coating material was prepared, and this coating material was applied on the same elastic layer as in Example 1 to form a surface resin layer having a thickness of 10 μm. Thus, a developing roller was obtained.

[Comparative Example 2]
A paint for the surface resin layer was prepared in the same manner as in Example 1 except that the silicone graft acrylic resin and the perfluoroalkyl group-containing acrylic resin were not blended, and this paint was applied on the elastic layer as in Example 1. A surface resin layer having a thickness of 10 μm was formed to obtain a developing roller.

[Comparative Example 3]
A coating material for the surface resin layer was prepared in the same manner as in Example 1 except that the perfluoroalkyl group-containing acrylic resin was not blended, and this coating material was applied on the elastic layer as in Example 1 to a thickness of 10 μm. A surface resin layer was formed to obtain a developing roller.

[Comparative Example 4]
A coating for the surface resin layer was prepared in the same manner as in Example 1 except that the silicone graft acrylic resin was not blended. And a developing roller was obtained.

  For each of the developing rollers, the surface hardness is measured using a micro rubber hardness meter (“MD-1” manufactured by Kobunshi Keiki Co., Ltd.) and the coefficient of static friction (JIS K7125) is set to “Tribogear μs Type 94i” (manufactured by HEIDON). The surface roughness Ra, Rz (JIS B0601-1994) was further measured. The results are shown in Table 1. The roller resistance value was measured by the following method, and the photoreceptor contamination, image density, fog resistance, and toner filming resistance were evaluated by the following methods. The results are also shown in Table 1.

[Roller resistance value]
With the developing roller pressed in parallel with the flat plate electrode and a weight of 500 g applied to both ends of the core bar in the direction of the flat plate electrode, a voltage of DC 100 V was applied between the core bar and the flat plate electrode, and the current flowing at that time Was measured, and the resistance was calculated from the current value.

[Photoconductor contamination]
The developing roller is pressed against the photosensitive drum with a load of 1 kg and left under high temperature and high humidity of 40 ° C. and 95% RH, and after one week, the developing roller and the photosensitive drum are incorporated into an actual machine (“LBP4600” manufactured by Hured Packard). Then, the image was printed out, and the contamination on the surface of the photosensitive drum at the portion that had been in contact with the developing roller for one week was evaluated according to the following criteria.
○: No contamination of the photosensitive drum was observed.
Δ: Slight contamination of the photosensitive drum was observed.
X: Bleed and obvious contamination was observed on the photosensitive drum.

[Image density]
The developing roller is incorporated in the toner cartridge, and is in a low temperature and low humidity (15 ° C., 10% RH) environment (LL environment), in a normal temperature and normal humidity (25 ° C., 50% RH) environment (NN environment), and in a high temperature and high humidity (30 ° C. Under a 80% RH environment (HH environment), continuous image formation with a printing rate of 2% was performed using “Color LBP4600” manufactured by Hewlett-Packard Company, and solid images and halftone images were formed initially and after printing 5000 sheets. The density unevenness of the obtained image was visually evaluated according to the following criteria.
○: No density unevenness.
Δ: Some uneven density.
X: There is clear density unevenness.

[Cover resistance]
Each developing roller was incorporated into a laser beam printer ("LBP4600" manufactured by Hured Packard), and the printer was forcibly stopped during the printing of a solid white image, and the amount of toner flying to the photosensitive drum in the white background portion was evaluated. The evaluation was carried out by comparing the density by tape transfer (measured with a Macbeth densitometer) and performing a three-level evaluation according to the following criteria.
○: Less than 0.15 Δ: 0.15 or more, less than 0.20 ×: 0.20 or more

[Toner filming resistance]
A toner was applied to the surface of the developing roller, incorporated into a toner cartridge, and left to stand at 40 ° C. and 95% RH for 1 week, and then an image was formed. The toner filming resistance was evaluated according to the following criteria.
○: No toner adhered to the developing roller surface from the first sheet.
Δ: No toner adhered to the surface of the developing roller by the 10th sheet.
X: Toner adhered to the surface of the developing roller even when the number of sheets exceeded 10.

  As shown in Table 1, it was confirmed that the developing roller of the present invention was excellent in durability, toner chargeability, and toner filming resistance, and a good image could be obtained reliably.

It is a schematic sectional drawing which shows an example of this invention developing roller. It is the schematic which shows an example of the developing mechanism using a developing roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core metal 2 Elastic layer 3 Surface resin layer 4 Toner conveyance roller 5 Developing roller 6 Photosensitive drum (latent image holding body)
7 Lamination blade 8 Transfer section 9 Paper (recording medium)
10 Cleaning unit 11 Cleaning blade t Toner

Claims (6)

In the developing roller formed by forming a semiconductive elastic layer around the core metal and further forming a surface resin layer directly or via an intermediate layer on the elastic layer,
The elastic layer is made of a urethane foam, and the surface resin layer is formed of a resin composition containing a urethane resin, a silicone graft acrylic resin, and a perfluoroalkyl group-containing resin. Development roller.   The developing roller according to claim 1, wherein the urethane resin contained in the surface resin layer is a lactone-modified polyol.   The developing roller according to claim 1 or 2, wherein the urethane foam forming the elastic layer has closed cells foamed by mechanical stirring foaming.   The developing roller according to any one of claims 1 to 3, wherein a static friction coefficient of the surface of the surface resin layer is 0.1 to 0.6 µs.   The developing roller according to claim 1, wherein a urethane resin layer formed by applying a urethane emulsion paint between the elastic layer and the surface resin layer is provided as an intermediate layer.   In an image forming apparatus provided with a developing mechanism for supplying a developer to a latent image holding member carrying an electrostatic latent image to visualize the electrostatic latent image, a developing roller for supplying the developer to the latent image holding member. An image forming apparatus using the developing roller according to claim 1.

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