JP4612830B2 - Developing roller and developing device for electrophotographic apparatus using the same - Google Patents

Description

  The present invention relates to a developing roller used in contact with a photoreceptor incorporated in an electrophotographic apparatus such as a copying machine, a printer, a facsimile receiving apparatus, and a developing apparatus for an electrophotographic apparatus using the same.

  2. Description of the Related Art As an electrophotographic apparatus such as a copying machine, a printer, and a facsimile receiving apparatus, an electrophotographic apparatus employing a pressure development method is known. The pressure development method is a development method that uses a non-magnetic one-component developer as the toner and attaches the developer to the latent image on the photosensitive drum to visualize the latent image. In addition to being easy to use, it is frequently used because it is easy to colorize toner. As shown in FIG. 3, an electrophotographic apparatus adopting such a pressure development method includes a photosensitive drum 15 rotated by a rotating mechanism, a charging roller 18 for charging the photosensitive member around the photosensitive member, and an image passing through the photosensitive drum 15. An exposure device L for forming an electrostatic latent image corresponding to an image on the photosensitive member by irradiating the photosensitive member with light and discharging a portion other than the portion corresponding to the image or a portion corresponding to the image. A developing device D that supplies toner to the developed electrostatic latent image and develops it, a transfer device 11 that transfers the toner adhering to the electrostatic latent image onto the transfer member, and further transfers and fixes the toner on the transfer member onto the recording material. The image forming apparatus includes a transfer / fixing device F and a cleaning device 19 that removes electricity and cleans the surface of the photoconductor after the toner is transferred. The developing device D includes a coating roller 16 for applying the toner to be stored on the surface of the developing roller 14, a developing blade 17 for adjusting the toner applied on the surface of the developing roller 14 into a more uniform thin layer, and a uniform developing blade. A developing roller 14 for supplying the toner to the photosensitive member is provided, and the developing roller 14 rotates while being in contact with or close to the photosensitive drum 15, so that the toner formed in a thin layer is transferred from the developing roller 14 to the photosensitive drum 15. The latent image is made visible by attaching to the latent image. In such a developing device, the developing roller carrying the toner of the non-magnetic one-component developer is brought into contact with the photosensitive drum holding the electrostatic latent image, and development is performed by attaching the toner to the latent image. It is necessary to form the developing roller with a conductive elastic body. Further, since the developing roller is in contact with the developing blade while waiting for operation or stopped, if the electrophotographic apparatus is not used for a certain period of time, a horizontal streak is generated at a portion contacting the developing blade. End up. For this reason, in addition to being a conductive elastic material as a material that can be used to produce the developing roller, it was locally loaded when the load was released after it was locally loaded by the developing blade. Strict conditions are required that parts can be restored immediately.

  On the other hand, the developing roller has a two-layer structure of inner and outer layers, the inner layer is a conductive elastic layer, the outer layer film is formed of a urethane-based resin, and the outer layer film includes magnesium oxide, zinc oxide, magnesium carbonate, One or more inorganic compounds of calcium oxide or calcium carbonate are added, and a developing device (Patent Document 1) for forming a copy image with a clear image and a uniform density, or a conductive elastic layer concentrically on the outer periphery of the rotating shaft In the developing roller formed by forming a surface layer on the outer periphery thereof, a thermoplastic urethane resin layer is disposed as an intermediate layer, and a silicon acrylic resin is disposed as an outermost layer, so that charging property and outermost layer under high temperature and high humidity are arranged. Excellent adhesion, etc. When used in an electrophotographic development process, the surface of the roller is not scraped even if it is printed over 10K (A4.5% printing density), and the non-image area fogging Etc. no image is obtained, and the developing roller for an electrophotographic apparatus can be suppressed scraping the photosensitive member due to low hardness (Patent Document 2) are known.

However, those that use these urethane-based resins as the developing roller have low hardness, and even if surface scraping can be avoided, development streaks due to parts that are locally subjected to a load by the developing blade for a certain period of time are improved. It was not something that was done.
JP 2002-311702 A JP 2002-207362 A

  The problem of the present invention is that in an image formed by an electrophotographic apparatus even in a room temperature and humidity environment, even after the electrophotographic apparatus is continuously put into a state where it is not operated for a long period of time, for example, one month, Providing a high-quality developing roller with excellent resilience and a developing device using the same, which can suppress the occurrence of horizontal streaks caused by the developing roller that is in contact with the developing blade and continuously receives a local load. There is to do.

  Unlike the case where adjustment is made by measuring the amount of macro deformation that has been conventionally performed, the inventors have changed the amount of change when the load is continuously applied after loading at a constant load application speed. By adjusting the amount of deformation in a very small area that does not exceed a certain value, lateral streaks caused by the developing roller that has been in contact with the developing blade and continuously received a local load for a long period of one month As a result, the present invention has been completed.

That is, the present invention provides a developing roller having a shaft body, and a conductive elastic layer and a conductive resin layer sequentially laminated on the shaft body, the surface of the roller being 100/60 mN in a normal temperature and humidity environment. When the load is applied from the unloaded condition at a load application speed of / mm ² / s and reaches 100 mN / mm ² , the deformation amount is h1 (μm), and then a load of 100 mN / mm ² is continuously applied for 30 minutes. the deformation amount when when the h2 ([mu] m), meets the relationship h2-h1 <6.0μm,
The conductive resin layer includes a component (a) to (d).
(A) a bifunctional polyurethane polyglycol or a bifunctional polyurethane glycol having a molecular weight Mw of 10,000 to 50,000 and a molecular weight distribution Mz / Mw of 2.5 or less,
(B) a high molecular weight polyisocyanate having a molecular weight Mw of from 5,000 to 50,000,
(C) a low molecular polyol having a molecular weight Mw of 800 or less,
(D) Low molecular isocyanate having a molecular weight Mw of 800 or less.
Further, the present invention provides a developing roller having a shaft body, a conductive elastic layer and a conductive resin layer sequentially laminated on the shaft body, wherein the conductive resin layer constitutes a surface layer. The developing roller, wherein the conductive resin layer is obtained by curing a raw material containing the following components (a) to (d):
(A) a bifunctional polyurethane polyglycol having a molecular weight Mw of 10,000 to 50,000 and a molecular weight distribution Mz / Mw of 2.5 or less,
(B) a high molecular weight polyisocyanate having a molecular weight Mw of from 5,000 to 50,000,
(C) a low molecular polyol having a molecular weight Mw of 800 or less,
(D) It relates to a low molecular isocyanate having a molecular weight Mw of 800 or less.

  The developing roller of the present invention can be used as a developing blade in an image formed by an electrophotographic apparatus even after the electrophotographic apparatus has been left unoperated for a long period of time in a room temperature and humidity environment. It is possible to suppress the occurrence of lateral streaks due to the developing roller that has been in contact with and continuously receives a local load, and is of high quality with excellent resilience.

The developing roller of the present invention is a developing roller having a shaft body, a conductive elastic layer and a conductive resin layer sequentially laminated on the shaft body. When the load is applied from a no-load state at 100/60 mN / mm ² / s load application speed at 50% RH, etc., the deformation amount is 100 mN / mm ² and is h1 (μm), and then continues for 30 minutes. deformation amount when a load of 100 mN / mm ² Te when you and h2 ([mu] m), meets the relationship h2-h1 <6.0μm,
The conductive resin layer comprises components (a) to (d)
(A) a bifunctional polyurethane polyglycol or a bifunctional polyurethane glycol having a molecular weight Mw of 10,000 to 50,000 and a molecular weight distribution Mz / Mw of 2.5 or less,
(B) a high molecular weight polyisocyanate having a molecular weight Mw of from 5,000 to 50,000,
(C) a low molecular polyol having a molecular weight Mw of 800 or less,
(D) Low molecular isocyanate having a molecular weight Mw of 800 or less.
If it contains , it will not restrict | limit in particular. The measurement of the deformation amount of the developing roller can be performed, for example, using a hardness measuring device such as an ultra micro hardness meter H-100V manufactured by Fischer. Specifically, the indenter is pushed in at a load application speed of 100/60 mN / mm ² / s, the deformation amount h1 (μm) when reaching 100 mN / mm ² , and then 100 mN / mm ^{2 for} 30 minutes The amount of deformation at that time can be measured by measuring h2 (μm).

  The shaft used in the developing roller of the present invention functions as a supporting member for the developing roller, and also allows the toner attached to the surface of the developing roller to be transferred to an electrostatic latent image on the photoreceptor. In relation to the electrostatic latent image, those that can serve as electrodes for making the surface of the developing roller have appropriate conductivity are preferable, and for example, those made of a conductive material such as a metal such as aluminum, iron, stainless steel, or an alloy are preferable. The shaft body is preferably a cylindrical body, and the outer diameter can be appropriately selected in relation to the electrophotographic apparatus to be mounted. For example, a shaft in the range of 4 to 10 mm can be specifically mentioned.

The conductive elastic layer provided on the outer periphery of the shaft body provides conductivity by using an elastomer such as ethylene-propylene-diene copolymer rubber (EPDM) or urethane, foam material, or other resin as a base material. In order to achieve this, an electron conductive material or an ion conductive material is blended, and a resin having a suitable resistance region of 10 ³ to 10 ¹⁰ Ωcm, preferably 10 ⁴ to 10 ⁸ Ωcm, is used.

  Specific examples of the material used as the base material include polyurethane, natural rubber, butyl rubber, nitrile rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber, styrene-butadiene rubber, ethylene-propylene rubber, and ethylene-propylene-diene rubber. Chloroprene rubber, acrylic rubber, and mixtures thereof, among which silicone rubber and EPDM are preferable because the developing roller of the present invention can have a specific amount of deformation with respect to load. .

  Examples of the electronic conductive material blended to impart conductivity to the substrate include conductive carbon such as ketjen black EC and acetylene black, SAF, ISAF, HAF, FEF, GPF, SRF, FT, MT, etc. Examples include carbon for rubber, carbon for color (ink) subjected to oxidation treatment, metals such as copper, silver, and germanium, and metal oxides. Among these, carbon black that can easily control the conductivity with a small amount is preferable. The blending amount of these electronic conductive materials is usually preferably 0.5 to 50 parts by weight, particularly preferably 1 to 30 parts by weight with respect to 100 parts by weight of the substrate.

  Examples of the ionic conductive material blended to impart conductivity to the substrate include inorganic ionic conductive materials such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride, and modified aliphatics. An organic ionic conductive material such as dimethylammonium ethosulphate or stearylammonium acetate is used.

  In addition, the rubber material used for the production of the conductive elastic layer can appropriately contain various additives such as a non-conductive filler, a crosslinking agent, and a catalyst within a range that does not impair these functions. Non-conductive fillers such as diatomaceous earth, silica, quartz powder, titanium oxide, zinc oxide, aluminosilicate, calcium carbonate, and a crosslinking agent can be contained.

  The hardness of such a conductive elastic layer is preferably an ASKER-C hardness of 25 to 60 °. The ASKER-C hardness is a hardness measured using an ASKER-C spring rubber hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) in accordance with the Japan Rubber Association standard SRIS0101. Specifically, for a roller left at room temperature and normal humidity, for example, 23 ° C. and 55% RH for 5 hours or more, 30 seconds after the hardness meter is brought into contact with the center of the roller with a force of 1 kg. It is a measured value. It is preferable that the conductive elastic layer has such a hardness because the developing roller of the present invention can have a specific amount of deformation with respect to the load.

  The thickness of such a conductive elastic layer can be appropriately selected depending on the toner type and the developing device used, but is preferably adjusted to 1 to 10 mm. Within this range, the developing roller can have an appropriate nip width and nip pressure.

  The conductive resin layer in the developing roller of the present invention includes, as a substrate, polyamide resin, urethane resin, urea resin, imide resin, melamine resin, fluororesin, phenol resin, alkyd resin, silicone resin, polyester resin, polyether resin, and the like. Of these, urethane resins are preferred because of their high ability to charge toner by friction and wear resistance.

Furthermore, this urethane resin contains the components (a) to (d) .
(A) a bifunctional polyurethane polyglycol having a molecular weight Mw of 10,000 to 50,000 and a molecular weight distribution Mz / Mw of 2.5 or less, or a bifunctional polyurethane glycol (b) a polymer polyisocyanate having a molecular weight Mw of 5,000 to 50,000 c) Low molecular polyol having a molecular weight Mw of 800 or less (d) Low molecular isocyanate having a molecular weight Mw of 800 or less As the bifunctional polyurethane polyglycol of the component (a), polyglycol which is a polymer of glycol and bifunctional polyurethane It is preferable to use a linear bifunctional polyurethane polyglycol obtained by copolymerizing an isocyanate compound by chain extension, because it is possible to improve the resilience after local loading of the developing roller. The bifunctional polyurethane polyglycol becomes the final form by determining the distance between crosslinks and the molecular weight by reaction with a polyfunctional isocyanate compound (including terminal isocyanate type prepolymer) as component (d) described later. Specific examples of the polyglycol used as a raw material for the polyurethane polyglycol include ethylene glycol, propylene glycol, tetramethylene glycol, ester glycol, acetal glycol, carbonate glycol, butadiene glycol, 1,2-butylene glycol, 1, Examples thereof include one polymer or two or more copolymers of glycols selected from 3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, and the like. Specific examples include diethylene glycol and triethylene glycol. , Polytetramethylene glycol, polypropylene glycol, polyethylene glycol, polyester glycols, polyacetal glycol, polycarbonate glycol, polybutadiene Call, polybutylene glycol, poly neopentyl glycol, and the like. Of these, polyglycols such as polypropylene glycol and polytetramethylene glycol, which have strong molecular crystallinity of the polyol itself, are preferred.

  Specific examples of the bifunctional isocyanate compound used as a raw material for the bifunctional polyurethane polyglycol include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), and tolidine diisocyanate (TODI). ), Hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), phenylene diisocyanate (PPDI), xylene diisocyanate (XDI), tetramethylxylene diisocyanate (TMXDI), cyclohexane diisocyanate and the like. Among these, aromatic isocyanate compounds such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), phenylene diisocyanate (PPDI), xylene diisocyanate (XDI), tetramethylxylene diisocyanate (TMXDI) In particular, diphenylmethane diisocyanate (MDI) is preferable because it can improve the resilience of the developing roller after a local load.

  As the bifunctional polyurethane glycol of component (a), those obtained by polymerizing the above exemplified glycol and the above exemplified bifunctional isocyanate compound can be used.

  The weight average molecular weight Mw of such a bifunctional polyurethane polyglycol or bifunctional polyurethane glycol is in the range of 10,000 to 50,000, and the molecular weight dispersion is such that Mz / Mw is 2.5 or less. It is preferable because the restorability after a typical load can be improved. Mw represents the weight average molecular weight, Mz represents the Z average molecular weight that places the highest importance on the contribution of the high molecular weight compound to the average molecular weight, and when there are Ni molecules of molecular weight Mi in the polymer, it is represented by the following formula: The

Mz = (ΣMi ³ Ni) / (ΣMi ² Ni)
Specific examples of the polymer polyisocyanate (b) include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate. (IPDI), phenylene diisocyanate (PPDI), xylene diisocyanate (XDI), tetramethylxylene diisocyanate (TMXDI), cyclohexane diisocyanate and other prepolymer types, urethane modified, allophanate modified, biuret modified and isocyanurate modified Examples include types. These polymer polyisocyanates preferably have a molecular weight Mw of 5,000 or more and 50,000 or less. When the molecular weight Mw is within this range, it is preferable because the restoration property after local load of the developing roller can be improved.

  As the low molecular polyol of the component (c), bifunctional ones such as tetramethylene glycol and hexamethylene glycol can be used, and trifunctional or higher functional polyols can also be used as the component (c). Etc. can also be used. The low molecular polyol preferably has a molecular weight Mw of 800 or less. When the molecular weight Mw is within this range, it is preferable because the resilience after receiving a local load on the developing roller can be improved.

  Examples of the low molecular isocyanate compound of the component (d) include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI). , Phenylene diisocyanate (PPDI), xylene diisocyanate (XDI), tetramethylxylene diisocyanate (TMXDI), cyclohexane diisocyanate, etc. can be used, and these modified types of trifunctional or higher functional isocyanates are also used as component (d) These oligomers can also be used. The low molecular isocyanate compound preferably has a molecular weight Mw of 800 or less. When the molecular weight Mw is within this range, it is preferable because the resilience after receiving a local load on the developing roller can be improved.

  This conductive resin layer contains an electron conductive material or an ion conductive material in order to impart conductivity. Examples of the electronic conductive material include conductive carbon such as ketjen black EC and acetylene black, rubber carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, and a color treated with oxidation ( Ink), metals such as carbon, copper, silver, germanium, and metal oxides may be mentioned. Of these, carbon black is preferable because the conductivity can be easily controlled with a small amount. Examples of ionic conductive materials include inorganic ionic conductive materials such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride, and organic ionic properties such as modified aliphatic dimethyl ammonium etosulphate and stearyl ammonium acetate. Mention may be made of conductive materials.

The content of such a conductive material in the conductive resin layer can be appropriately selected depending on the range of conductivity required for the developing roller in relation to the toner and the photoreceptor to which the toner is supplied. The conductivity required for a developing roller used in a developing device using a non-magnetic one-component developer is preferably adjusted to a resistance range of 10 ³ to 10 ⁸ Ωcm, and more preferably 10 ^4. a to 10 ⁷ [Omega] cm, in order to the developing roller having such a conductivity, when the resin component is 100 parts by mass, the conductive material may be such as the percentage of 1 to 50 parts by weight .

  Further, the conductive resin layer may contain particles for forming a surface roughness in order to keep the toner delivered to the photoreceptor on the surface. Examples of such roughened particles include rubber particles such as EPDM, NBR, SBR, CR, and silicone rubber, or elastomer particles such as polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyester, and polyamide-based thermoplastic elastomer (TPE). Or resin particles such as PMMA particles, urethane resin particles, fluorine resin, silicone resin, phenol resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer, polyacrylonitrile resin alone or They can be used in combination. Such particles can have a particle diameter of 1 to 30 μm, for example, and can be 1 to 50 parts by weight, for example, with respect to 100 parts by weight of the resin forming the conductive resin layer. The resin particles contained within this range can form irregularities that can hold the toner on the surface of the developing roller, eliminating the need to roughen the surface. The surface roughness Rz (JIS B0601: 2001) of the developing roller is generally adjusted to 1 to 15 μm, more preferably 3 to 10 μm.

  In addition, the conductive resin layer can contain various additives such as a non-conductive filler, a crosslinking agent, and a catalyst as long as they do not impair these functions. For example, diatomaceous earth, silica, quartz powder, Non-conductive fillers such as titanium oxide, zinc oxide, aluminosilicic acid, calcium carbonate, crosslinking agents, adjusting agents for adjusting hardness, and the like can be contained.

  Moreover, it is preferable that it is 1.0-30 micrometers, and, as for the thickness of a conductive resin layer, it is more preferable that it is 3.0-20 micrometers.

  The developing roller of the present invention, after processing the surface of the shaft body, using a mold on which the shaft body is set, injecting a resin liquid for preparing a conductive elastic layer in which carbon black is mixed with silicone resin into the cavity, The conductive elastic layer is prepared by appropriately heating and curing the resin. In order to produce a conductive resin layer on the conductive elastic layer, the above components (a) to (d) and a conductive material such as an electronic conductive material or an ionic conductive material are used, for example, a roll kneader, a Banbury mixer, a ball mill, Kneading using a sand grinder, paint shaker, etc., mixing and stirring, adding and dispersing rough particles to form the developing roller surface roughness as needed and dispersing, then adding a curing agent or curing catalyst and stirring The paint obtained by this is applied onto the conductive elastic layer by a method such as air spray, roll coat, curtain coat, dipping or the like. After the application, the resin is cured at an appropriate curing temperature to produce a conductive resin layer and obtain a developing roller. As a simple method, a dip coating method for overflowing the paint from the upper end of the dip tank as described in JP-A-57-5047 can also be applied.

  An example of the developing roller of the present invention will be described with reference to the drawings. As shown in the cross-sectional views of FIGS. 1 and 2, the conductive elastic layer 2 is formed on the outer peripheral surface of a columnar or hollow cylindrical shaft 1. And a developing roller having a configuration in which the conductive resin layers 3 are sequentially laminated. Further, as the developing roller of the present invention, elasticity that adds another function to the inner periphery of the conductive elastic layer 2, between the conductive elastic layer 2 and the conductive resin layer 3, or to the outer periphery of the conductive resin layer 3. One or more layers or resin layers may be laminated.

  The developing apparatus for an electrophotographic apparatus of the present invention is not particularly limited as long as it is a developing apparatus provided in an electrophotographic apparatus such as a copying machine, a facsimile, or a printer. For example, the electrophotographic apparatus such as a copying machine shown in FIG. Examples of the developing device of the apparatus include those equipped with the developing roller of the present invention.

  FIG. 2 is a schematic configuration diagram illustrating an example of an image forming apparatus using the developing device for an electrophotographic apparatus of the present invention.

  In the image forming apparatus as an example using the developing device for an electrophotographic apparatus of the present invention, as shown in FIG. 2, a photosensitive drum 21 as a latent image carrier rotates in the direction of arrow A to charge the photosensitive drum 21. An electrostatic latent image is formed on the surface of the photosensitive member 21 by a laser beam 23 that is uniformly charged by the charging member 22 for processing and is an exposure means for writing the electrostatic latent image on the photosensitive drum 21. The electrostatic latent image is developed by being provided with toner as a developer by a developing device 24 that is disposed in proximity to the photosensitive drum 21 and is held in a process cartridge that is detachable from the image forming apparatus main body. Visualized as an image. Development in this image forming apparatus is so-called reversal development in which a toner image is formed on an exposed portion, and the visualized toner image on the photosensitive drum 21 is transferred to a paper 33 as a recording medium by a transfer roller 29 as a transfer member. The The paper 33 to which the toner image has been transferred is subjected to a fixing process by the fixing device 32, discharged outside the device, and the printing operation is completed.

  On the other hand, the untransferred residual toner remaining on the photosensitive drum 21 without being transferred is scraped off by a cleaning blade 30 which is a cleaning member for cleaning the surface of the photosensitive member, and stored in a waste toner container 31 to be cleaned. The drum 21 repeats the above operation.

  The developing device 24 for an electrophotographic apparatus of the present invention in such an image forming apparatus has a developing container 34 containing a non-magnetic toner 28 as a one-component developer and an opening extending in the longitudinal direction in the developing container 34. The developing roller 25 according to the present invention is provided as a developer carrying member positioned and opposed to the photosensitive drum 21, and the electrostatic latent image on the photosensitive drum 21 is developed and visualized.

  Such an image forming apparatus is configured as an electrophotographic process cartridge having a developing device and at least one of a latent image carrier, a charging member, a cleaning member, and a transfer member, which are integrally held. The electrophotographic process cartridge may be detachable from the image forming apparatus.

  The developing roller 25 is in contact with the photosensitive drum 21 with a contact width. In the developing device 24, the elastic roller 26 is abutted in the developing container 25 on the upstream side in the rotation direction of the developing roller 25 with respect to the abutting portion of the elastic blade 27 as a developer regulating member with the surface of the developing roller 25 in the developing container 34. And it is rotatably supported.

  As the structure of the elastic roller 26, a foamed skeleton-like sponge structure or a fur brush structure in which fibers such as rayon or nylon are planted on a core metal is used for supplying the toner 28 to the developing roller 25 and stripping off the undeveloped toner. It is preferable from the point. For example, an elastic roller 26 with a diameter of 16 mm in which a polyurethane foam is provided on a core metal can be used. The contact width of the elastic roller 26 with respect to the developing roller 25 is preferably 1 to 8 mm, and it is preferable to have a relative speed at the contact portion with respect to the developing roller 25. For example, the contact width is set to 3 mm. It can be set and rotated at a predetermined timing by a driving means (not shown) such that the peripheral speed of the elastic roller 26 is 50 mm / s during development operation (the relative speed with respect to the developing roller 25 is 130 mm / s). .

The developing roller of the present invention will be described below with reference to examples and comparative examples, but the technical scope of the present invention is not limited to these examples.
[Example 1]
A cored bar with an outer diameter of 8 mm as a shaft is placed coaxially in a cylindrical mold with an inner diameter of 16 mm, and liquid conductive silicone rubber (ASKER-C hardness 40 degrees by Toray Dow Silicone Co., Ltd.) is used as a conductive elastic layer. After casting, volume resistivity 10E7Ω · cm product is placed in an oven at 130 ° C, heat-molded for 20 minutes, and after mold removal, secondary vulcanization is performed in an oven at 200 ° C for 4 hours. Obtained.

  As a material for the conductive resin layer, polytetramethylene glycol (trade name: PTG1000SN; molecular weight Mn = 1000, f = 2; manufactured by Hodogaya Chemical Co., Ltd.) 100 parts by mass, isocyanate (trade name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) 18.7 parts by mass are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 3 hours in a nitrogen atmosphere to obtain a molecular weight Mw = 10000 and a hydroxyl value of 18.2. As a component (a) having a molecular weight dispersity Mz / Mw = 1.6, a bifunctional polyurethane polyglycol prepolymer was obtained.

The obtained bifunctional polyurethane polyglycol prepolymer (a) and the following components were uniformly dispersed and mixed to obtain a raw material liquid for the conductive surface layer.
(A) Polyurethane polyglycol prepolymer 100 parts by mass (b) Urethane-modified MDI Mw = 50000 90 parts by mass (c) Ether urethane polyol Mw = 800 100 parts by mass (d) TMP-modified TDI (B830; manufactured by Mitsui Takeda Polyurethane) 25 parts by mass carbon black (printex35; manufactured by Degussa) 15 parts by mass acrylic resin particles (MBX-12; particle size 12 μm; manufactured by Sekisui Plastics Co., Ltd.) 10 parts by mass In the raw material liquid for this conductive surface layer, The shaft body after the formation of the conductive elastic layer was dipped to coat the outer surface of the conductive elastic layer, and then pulled up and dried naturally. Next, the coated raw material was cured by heat treatment at 140 ° C. for 1 hour, and a conductive resin layer was formed to produce a developing roller.
[Example 2]
A developing roller is manufactured by coating a conductive resin layer by the following procedure using a conductive elastic layer having the same composition and thickness as the developing roller manufactured in Example 1 on a shaft body. did.

  As a material for the conductive resin layer, polytetramethylene glycol (trade name: PTG1000SN; molecular weight Mn = 1000, f = 2 (f represents the number of functional groups); manufactured by Hodogaya Chemical Co., Ltd.) Name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) 21.2 parts by mass are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 6 hours in a nitrogen atmosphere to obtain a molecular weight Mw A bifunctional polyurethane polyglycol prepolymer was obtained as the component (a) having 50000, a hydroxyl value of 5.6, and a molecular weight dispersity of Mz / Mw = 2.5.

The obtained bifunctional polyurethane polyglycol prepolymer (a) and the following components were uniformly dispersed and mixed to obtain a raw material liquid for the conductive surface layer.
(a) Polyurethane polyglycol prepolymer 100 parts by mass
(b) Urethane modified MDI Mw = 5000 43 parts by mass
(c) 1,4-butanediol 2 parts by mass
(d) TMP-modified TDI (B830; manufactured by Mitsui Takeda Polyurethane Co., Ltd.) 17 parts by mass carbon black (printex 35; manufactured by Degussa) 15 parts by mass acrylic resin particles (MBX-12; particle size 12 μm; manufactured by Sekisui Plastics Co., Ltd.) 10 Part by mass The shaft after finishing the formation of the conductive elastic layer was immersed in the raw material liquid for the conductive resin layer to coat the outer surface of the conductive elastic layer, and then pulled up and naturally dried. Next, the coated raw material was cured by heat treatment at 140 ° C. for 1 hour, and a conductive resin layer was formed to produce a developing roller.
[Example 3]
A developing roller is manufactured by coating a conductive resin layer by the following procedure using a conductive elastic layer having the same composition and thickness as the developing roller manufactured in Example 1 on a shaft body. did.

  As a material for the conductive resin layer, polytetramethylene glycol (trade name: PTG1000SN; molecular weight Mn = 1000, f = 2; manufactured by Hodogaya Chemical Co., Ltd.) 100 parts by mass, isocyanate (trade name: Millionate MT; MDI, f = 2; made by Nippon Polyurethane Industry Co., Ltd.) 20.0 parts by mass are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 4 hours in a nitrogen atmosphere. Molecular weight Mw = 40000, hydroxyl value 8.4, molecular weight A bifunctional polyurethane polyglycol prepolymer was obtained as component (a) having a dispersity Mz / Mw = 2.0.

The obtained bifunctional polyurethane polyglycol prepolymer (a) and the following components were uniformly dispersed and mixed to obtain a raw material liquid for the conductive resin layer.
(a) Polyurethane polyglycol prepolymer 100 parts by mass
(b) Urethane modified MDI Mw = 10000 43 parts by mass
(c) 1,4-butanediol 2 parts by mass
(d) Polymeric MDI 17 parts by mass carbon black (printex35; manufactured by Degussa) 15 parts by mass acrylic resin particles (MBX-12; particle size 12 μm; manufactured by Sekisui Plastics Co., Ltd.) 10 parts by mass In this conductive resin raw material liquid The shaft body after the formation of the conductive elastic layer was dipped to coat the outer surface of the conductive elastic layer, and then pulled up and dried naturally. Next, the coated raw material was cured by heat treatment at 140 ° C. for 1 hour, and a conductive resin layer was formed to produce a developing roller.
[Example 4]
A developing roller is manufactured by coating a conductive resin layer by the following procedure using a conductive elastic layer having the same composition and thickness as the developing roller manufactured in Example 1 on a shaft body. did.

  As a material for the conductive resin layer, 100 parts by mass of polypropylene glycol (molecular weight Mn = 1000, f = 2) and isocyanate (trade name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) 19.9 masses Parts are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 3 hours under a nitrogen atmosphere to obtain a molecular weight Mw = 30000, a hydroxyl value of 8.4, and a molecular weight dispersity Mz / Mw = 1.8 (a As a component, a bifunctional polyurethane polyglycol prepolymer was obtained.

The obtained bifunctional polyurethane polyglycol prepolymer (a) and the following components were uniformly dispersed and mixed to obtain a raw material liquid for the conductive resin layer.
(a) Polyurethane polyglycol prepolymer 100 parts by mass
(b) Urethane modified MDI Mw = 10000 43 parts by mass
(c) 1,4-butanediol 2 parts by mass
(d) TMP modified TDI (B830; manufactured by Mitsui Takeda Polyurethane Co., Ltd.) 17 parts by mass carbon black (printex 35; manufactured by Degussa) 15 parts by mass acrylic resin particles (MBX-12; particle size 12 μm; manufactured by Sekisui Plastics Co., Ltd.) 10 Part by mass The shaft after finishing the formation of the conductive elastic layer was immersed in the raw material liquid for the conductive resin layer to coat the outer surface of the conductive elastic layer, and then pulled up and naturally dried. Next, the coated raw material was cured by heat treatment at 140 ° C. for 1 hour, and a conductive resin layer was formed to produce a developing roller.
[Comparative Example 1]
A developing roller is manufactured by coating a conductive resin layer by the following procedure using a conductive elastic layer having the same composition and thickness as the developing roller manufactured in Example 1 on a shaft body. did.

  As a material for the conductive resin layer, 100 parts by mass of polytetramethylene glycol (trade name: PTG1000SN; molecular weight Mn = 1000; f = 2; manufactured by Hodogaya Chemical Co., Ltd.) and isocyanate (trade name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) 22.4 parts by mass are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 6 hours in a nitrogen atmosphere. Molecular weight Mw = 60000, hydroxyl value 5.3 As a component (a ′) having a molecular weight dispersity Mz / Mw = 2.5, a bifunctional polyurethane polyglycol prepolymer was obtained.

The obtained bifunctional polyurethane polyglycol prepolymer (a ′) and the following materials were uniformly dispersed and mixed to obtain a raw material liquid for the conductive resin layer.
(a´) Polyurethane polyglycol prepolymer 100 parts by mass
(d) TMP-modified TDI (B830; manufactured by Mitsui Takeda Polyurethane Co., Ltd.) 18 parts by mass carbon black (printex 35; manufactured by Degussa) 15 parts by mass acrylic resin particles (MBX-12; particle size 12 μm; manufactured by Sekisui Plastics Co., Ltd.) 10 Part by mass The shaft after finishing the formation of the conductive elastic layer was immersed in the raw material liquid for the conductive resin layer to coat the outer surface of the conductive elastic layer, and then pulled up and naturally dried. Next, the coated raw material was cured by heat treatment at 140 ° C. for 1 hour, and a conductive resin layer was formed to produce a developing roller.
[Comparative Example 2]
A developing roller is manufactured by coating a conductive resin layer by the following procedure using a conductive elastic layer having the same composition and thickness as the developing roller manufactured in Example 1 on a shaft body. did.

  As a material for the conductive resin layer, polytetramethylene glycol (trade name: PTG1000SN; molecular weight Mn = 1000, f = 2; manufactured by Hodogaya Chemical Co., Ltd.) 100 parts by mass, isocyanate (trade name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) 18.3 parts by mass are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 3 hours in a nitrogen atmosphere to obtain a molecular weight Mw = 7000 and a hydroxyl value of 22.6. A polyurethane glycol prepolymer was obtained as a bifunctional (a ′) component having a molecular weight dispersity Mz / Mw = 1.4.

The obtained bifunctional polyurethane polyglycol prepolymer and the following materials were uniformly dispersed and mixed to obtain a raw material liquid for the conductive resin layer.
(a´) Polyurethane glycol prepolymer 100 parts by mass
(b) Urethane-modified MDI Mw = 60000 28 parts carbon black (printex35; manufactured by Degussa) 15 parts acrylic resin particles (MBX-12; particle size 12 μm; manufactured by Sekisui Plastics Co., Ltd.) 10 parts by weight This conductive resin The shaft body after the formation of the conductive elastic layer was immersed in the layer raw material liquid to coat the outer surface of the conductive elastic layer, and then pulled up and naturally dried. Subsequently, the coated raw material was cured by heat treatment at 140 ° C. for 1 hour, and a conductive resin layer was formed thereon to produce a developing roller.
[Measurement of deformation]
The developed developing roller is allowed to stand in a room temperature and humidity environment for 48 hours, and then the indenter of the square weight is vertically moved using a hardness measuring device such as Fischer's ultra micro hardness tester H-100V in a room temperature and humidity environment. When the load is 100/60 mN / mm ² / sec. And the load reaches 100 mN / mm ² , the deformation is h1 (μm), and then the same load is applied for 30 minutes. The amount of deformation was set to h2 (μm), and the value of h2−h1 was obtained.
[Image evaluation]
The produced developing roller was mounted on an electrophotographic process cartridge, an image was actually formed with a color laser printer, and image evaluation was performed. As the toner used, magenta toner having a number average particle diameter of 7.0 μm was used.
[Horizontal streaks due to blade contact marks]
The horizontal streak evaluation by the blade contact mark of the developed developing roller is performed by leaving the electrophotographic process cartridge having the developing roller in a normal temperature / humidity environment (23 ° C./55% RH) for one month, and then in a normal temperature / humidity environment. An image was output, and whether or not horizontal streaks due to blade contact marks were observed was judged according to the following criteria.
○: No horizontal stripes are observed Δ: Horizontal stripes are slightly observed, but there is no practical problem.
X: Horizontal streak that causes a problem in the actual image is recognized.

The evaluation results for each roller are summarized in Table 1. As is clear from the results of Examples 1 to 4 shown in Table 1, in the developing roller having the shaft body, the conductive elastic layer provided on the shaft body, and the conductive resin layer constituting the outermost layer, The amount of deformation when the roller surface reaches 100 mN / mm ² at a load application speed of 100/60 mN / mm ² / s in a normal temperature and humidity environment (23 ° C / 50% RH) is h1 (μm) Then, when the deformation amount after 30 minutes is h2 (μm), the developing roller satisfying the relationship of h2-h1 <6.0 μm can effectively contact the developing blade even if left for one month in a normal temperature and humidity environment. It is clear that this is a high-quality developing roller in which no trace is generated. On the other hand, in Comparative Examples 1 and 2 where the change in the amount of change was outside the scope of the present invention, a contact mark of the developing blade when left for one month in a normal temperature and humidity environment occurred.

(A) It is sectional drawing perpendicular to an axial direction which shows an example of the developing roller of this invention. (B) It is sectional drawing of the axial direction which shows an example of the developing roller of this invention. 1 is a schematic configuration diagram showing an electrophotographic apparatus using a developing device for an electrophotographic apparatus of the present invention. It is a schematic block diagram which shows the electrophotographic apparatus using the conventional developing device.

Explanation of symbols

1: shaft body 2: conductive elastic layer 3: conductive resin layer 21: photosensitive drum 22: charging member 23: laser beam 24: developing device 25: developing roller 26: elastic roller 27: elastic blade 28: toner 29: transfer Roller 30: Cleaning blade 31: Waste toner container 32: Fixing device 33: Paper 34: Developer container

Claims (7)

In a developing roller having a shaft, and a conductive elastic layer and a conductive resin layer sequentially laminated on the shaft,
When the surface of the roller is loaded from an unloaded state at a load application speed of 100/60 mN / mm ² / s in a normal temperature and humidity environment, the amount of deformation when the roller surface reaches 100 mN / mm ² is h1 (μm), and then 30 minutes, when the deformation amount when a load of continuously 100 mN / mm ² was h2 ([mu] m), meets the relationship of h2-h1 <6.0 .mu.m,
The developing roller, wherein the conductive resin layer contains components (a) to (d):
(A) a bifunctional polyurethane polyglycol or a bifunctional polyurethane glycol having a molecular weight Mw of 10,000 to 50,000 and a molecular weight distribution Mz / Mw of 2.5 or less,
(B) a high molecular weight polyisocyanate having a molecular weight Mw of from 5,000 to 50,000,
(C) a low molecular polyol having a molecular weight Mw of 800 or less,
(D) Low molecular isocyanate having a molecular weight Mw of 800 or less. The component (a) is a bifunctional polyurethane polyglycol having a molecular weight Mw of 10,000 to 50,000 and a molecular weight distribution Mz / Mw of 2.5 or less, and the bifunctional polyurethane polyglycol is composed of polyglycol and bifunctional The developing roller according to claim 1 , wherein the developing roller is a copolymer with an isocyanate compound. The developing roller according to claim 2 , wherein the bifunctional isocyanate compound is diphenylmethane diisocyanate. The developing roller according to claim 2 or 3 , wherein the polyglycol is at least one selected from polypropylene glycol and polytetramethylene glycol. Electrophotographic apparatus for developing apparatus, comprising a developing roller according to any one of claims 1-4. In a developing roller having a shaft body, a conductive elastic layer and a conductive resin layer sequentially laminated on the shaft body, the conductive resin layer constituting a surface layer,
The developing roller, wherein the conductive resin layer is obtained by curing a raw material containing the following components (a) to (d):
(A) a bifunctional polyurethane polyglycol having a molecular weight Mw of 10,000 to 50,000 and a molecular weight distribution Mz / Mw of 2.5 or less,
(B) a high molecular weight polyisocyanate having a molecular weight Mw of from 5,000 to 50,000,
(C) a low molecular polyol having a molecular weight Mw of 800 or less,
(D) Low molecular isocyanate having a molecular weight Mw of 800 or less. The developing roller according to claim 6 , wherein (a) is a copolymer of diphenylmethane diisocyanate and at least one selected from polypropylene glycol and polytetramethylene glycol.

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