JP2010122352A - Developing roller, method for manufacturing developing roller, process cartridge and electrophotographic image forming apparatus - Google Patents

Abstract

The present invention provides a high-quality developing roller that is flexible and excellent in image durability and has a small increase in resistance during continuous energization, or a developing device, a process cartridge, and an image forming apparatus using such a developing roller. thing.
In a developing roller having a resin layer around a core and a surface layer on the outer periphery thereof, the surface layer comprises a) a binder resin component, b) conductive fine particles, and c) a number average particle diameter. The development roller is characterized in that it contains a microgel having a skeleton composed of at least one of methyl methacrylate, styrene, and urethane, and has a flexibility and image durability. A high-quality developing roller that is excellent and has a small increase in resistance during continuous energization and exhibits conductivity suitable as a developing roller can be obtained. Further, by using the developing roller, a high-quality developing device, a process cartridge, and an image forming apparatus can be obtained.
[Selection] Figure 1

Description

  The present invention relates to a developing roller used in contact with a photosensitive member, which is incorporated in an apparatus employing an electrophotographic system such as a copying machine, a printer, or a facsimile receiving apparatus.

  In a copying machine, facsimile, or printer using an electrophotographic system, a photosensitive member is charged by a charging unit, and an electrostatic latent image is formed by a laser. Next, the toner in the developing container is applied onto the developing roller by the toner application roller and the toner regulating member, and development with the toner is performed at the contact portion between the photosensitive member and the developing roller. Thereafter, the toner on the photoconductor is transferred onto a recording sheet by a transfer unit and fixed by heat and pressure, and the toner remaining on the photoconductor is removed by a cleaning blade.

Non-magnetic one-component contact developing type electrophotographic image forming apparatus includes an elastic roller having an electric resistance of 10 ³ to 10 ¹⁰ Ω · cm for charging a photoreceptor or developing an electrostatic latent image. Is used. In an electrophotographic image forming apparatus of a non-magnetic one-component contact developing system, toner is moved from a developing roller that is pressed against each other to a photoreceptor (drum) to develop an electrostatic latent image, and a toner image is formed. The developing roller used in such an electrophotographic image forming apparatus has a resin layer on the shaft core and further forms a single layer or a plurality of surface layers on the outer periphery in order to satisfy a higher level of quality. The semiconductive roller having the above-described configuration is used.

As a polymer elastic material for forming such a semiconductive roller, a polymer elastomer or a polymer foam having rubber elasticity is used. These are required to have low hardness, do not contaminate the photosensitive member and the transfer member, and do not fuse with the toner. Accordingly, solid rubber vulcanizates, polyurethanes, and the like are used as materials constituting polymer elastomers and polymer foams. Specific examples include solid rubber vulcanizates such as isoprene rubber, ethylene propylene rubber, silicone rubber, epichlorohydrin rubber, and acrylonitrile butadiene rubber, and polyurethane obtained by curing a liquid raw material such as polyol with isocyanate. Among these, a polyurethane produced using a polyol and a polyisocyanate as main raw materials is generally used. This is because conductivity can be imparted by both a conductive material and an electrolyte, and there is an advantage that the electrolyte can be used by dissolving it in a liquid raw material, and a foam can be formed if necessary.
In a semiconductive roller made of these materials, the roller resistance is adjusted to 10 ⁵ to 10 ⁹ Ω, which is a semiconductive region, by mixing conductive fine particles such as carbon black and metal oxide.

Patent Document 1 describes a method of obtaining a middle resistance region conductive roll by using a strong conductive carbon black and a weak conductive carbon black in combination without causing a significant increase in hardness.
JP 09-090714 A

  In recent years, the performance required for developing rollers used in electrophotographic systems such as copiers, printers, and facsimile machines has become more advanced, and more flexible and low in terms of higher image quality and energy saving. A toner having a melting point is used. Furthermore, in order to achieve stable electrical characteristics and achieve both high image quality and image durability as described above, flexible physical properties are particularly required.

In Patent Document 1, when a relatively high conductivity (10 ⁴ to 10 ⁸ Ω · cm) is required, the amount of carbon black added must be increased, and the surface layer may become hard. Further, continuous energization may cause an increase in electrical resistance (hereinafter referred to as energization deterioration).

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a high-quality developing roller having a small amount of deterioration due to energization and having appropriate conductivity and flexibility, a method for manufacturing the developing roller, and a process cartridge using the developing roller. And providing an electrophotographic image forming apparatus.

The inventors of the present invention have intensively studied and studied in order to provide a developing roller that meets the above-mentioned object, and have reached the present invention. That is, the present invention
A developing roller having a resin layer on the outer peripheral surface of the core and a surface layer on the outer peripheral surface of the resin layer, wherein the surface layer contains the following a), b) and c): About:
a) binder resin component,
b) conductive fine particles,
c) A microgel having a number average particle diameter of 60 nm or more and 100 nm or less and having a skeleton composed of at least one of methyl methacrylate, styrene, and urethane.

Further, the present invention provides a developing roller manufacturing method having a resin layer around the core and a surface layer on the outer periphery thereof.
A developing roller manufacturing method, wherein the surface layer is formed by mixing an organic solvent dispersion of microgel with a resin solution in which conductive fine particles are dispersed and mixed, and then applying the mixture to the surface of the resin layer. is there.

  According to another aspect of the present invention, there is provided a developing device having a container for containing toner and a developing roller, wherein the developing roller visualizes the latent image by applying the toner to a photoreceptor carrying the latent image. The present invention relates to a developing device that is a roller.

  The present invention also relates to a process cartridge having at least a developing roller attached thereto and detachable from an electrophotographic image forming apparatus, wherein the developing roller is the developing roller described above.

The present invention further includes a developing roller for carrying toner in a state of being opposed to a photosensitive member carrying a latent image, and the developing roller develops the latent image by applying toner to the photosensitive member. In the forming device,
The present invention relates to an electrophotographic image forming apparatus comprising the developing roller according to the present invention.

  According to the present invention, it is possible to obtain a high-quality developing roller that is less deteriorated in energization and has appropriate conductivity and flexibility. Further, by using the developing roller, a high-quality process cartridge and an electrophotographic image forming apparatus can be obtained.

  As shown in FIGS. 1 and 2, the developing roller 1 of the present invention has a resin layer 3 fixed to the outer peripheral surface of a columnar or hollow cylindrical conductive shaft core 2, and a surface layer on the outer peripheral surface of the resin layer 3. 4 is comprised from the electroconductive member laminated | stacked.

  The conductive shaft core 2 functions as an electrode and a support member of the developing roller 1, and is a metal or alloy such as aluminum, copper alloy or stainless steel; iron plated with chromium or nickel; It is made of a conductive material such as a synthetic resin. The outer diameter of the conductive shaft core 2 is usually in the range of 4 mm to 10 mm.

  The resin layer 3 has such hardness and elasticity as to be pressed against the photoconductor with an appropriate nip width and nip pressure so that the toner can be supplied to the electrostatic latent image formed on the photoconductor surface without excess or deficiency. To the developing roller. The resin layer 3 is usually formed of a molded body of rubber material. As the rubber material, various rubber materials conventionally used for conductive rubber rollers can be used. Examples of the rubber used for the rubber material include the following. Ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), fluorine rubber, Silicone rubber, epichlorohydrin rubber, hydride of NBR, urethane rubber. These can be used alone or in admixture of two or more. Among these, silicone rubber is particularly preferable from the viewpoint of set performance. Examples of the silicone rubber include polydimethylsiloxane, polymethyltrifluoropropylsiloxane, polymethylvinylsiloxane, polyphenylvinylsiloxane, and copolymers of these polysiloxanes.

  The resin layer 3 contains a conductivity-imparting agent, and various additives such as a non-conductive filler, a crosslinking agent, and a catalyst are appropriately blended. As the conductivity-imparting agent, fine particles of conductive metal such as graphite, carbon black, aluminum, and copper; conductive metal oxide such as zinc oxide, tin oxide, and titanium oxide can be used. Of these, carbon black is preferred because it is relatively easily available and provides good chargeability. Non-conductive fillers include silica, quartz powder, titanium oxide, zinc oxide or calcium carbonate. Examples of the crosslinking agent include di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and dicumyl peroxide.

As the volume resistivity of the resin layer 3, a value obtained by the following method can be adopted.
As the resistance meter, an ultrahigh resistance meter R8340A (manufactured by Advantest) is used for measurement under the following conditions.
Measurement mode: Program mode 5 (charge and measure 30 seconds, discharge 10 seconds)
Applied voltage: 100 (V)
Sample box: Sample box TR42 (manufactured by Advantest) for measuring ultrahigh resistance meter, the main electrode is a metal having a diameter of 10 mm and a thickness of 10 mm, and the guard ring electrode is a metal having an inner diameter of 20 mm and an outer diameter of 26 mm and a thickness of 10 mm.
Test piece: First, a flat test piece is produced by curing the material of the resin layer 2 to the same thickness as that of the resin layer 2 under the same conditions as those for molding the resin layer 2. Next, a test piece having a diameter of 30 mm is cut out from the test piece. On one side of the cut-out test piece, a vapor deposition film electrode (back surface electrode) is provided by performing Pt—Pd vapor deposition on the entire surface, and a main electrode film having a diameter of 15 mm is formed on the other surface by the same Pt—Pd vapor deposition film. A guard ring electrode film having an inner diameter of 18 mm and an outer diameter of 28 mm is provided concentrically. The Pt—Pd vapor-deposited film is obtained by performing a vapor deposition operation for 2 minutes at a current value of 15 mA using mild sputter E1030 (manufactured by Hitachi, Ltd.). The sample after the vapor deposition operation is used as a measurement sample.

  At the time of measurement, the main electrode having a diameter of 10 mm is placed so as not to protrude from the main electrode film having a diameter of 15 mm. Further, measurement is performed by placing a guard ring electrode having an inner diameter of 20 mm on the electrode film so as not to protrude from the guard ring electrode film having an inner diameter of 18 mm. The measurement is performed in an environment where the temperature is 23 ° C. and the relative humidity is 50%. Prior to the measurement, the measurement sample is left in the environment for 12 hours or more.

  In the above state, the volume resistance (Ω) of the test piece is measured. Next, when the measured volume resistance value is RM (Ω) and the thickness of the test piece is t (cm), the volume resistivity RR (Ωcm) of the test piece is obtained by the following equation.

RR (Ωcm) = π × 0.75 × 0.75 × RM (Ω) ÷ (4 × t (cm))
When carbon black is used as the conductivity-imparting agent, 15 to 80 parts by mass is blended with 100 parts by mass of rubber in the rubber material. Moreover, it is preferable that the thickness of the elastic layer 3 exists in the range of 2.0 mm-6.0 mm, and it is more preferable that it exists in the range of 3.0 mm-5.0 mm.

  Specific examples of the binder resin component a) contained in the surface layer 4 include amino resins such as polyurethane, polyester, polyether, acrylic, epoxy resin, and melamine. Polyurethane and melamine cross-linked resins are particularly preferred from the viewpoints of film strength and toner chargeability. Among them, thermosetting polyether polyurethane and polyester polyurethane are preferably used because they have the flexibility required for a developing roller.

  These thermosetting polyurethane resins are obtained by a reaction between a known polyether polyol or polyester polyol and an isocyanate compound.

  Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Moreover, as a polyester polyol, the following can be used. Diol components such as 1,4-butanediol, 3-methyl-1,4-pentanediol, neopentyl glycol, triol components such as trimethylolpropane, adipic acid, phthalic anhydride, terephthalic acid, hexahydroxyphthalic acid, etc. And polyester polyols obtained by condensation reaction with dicarboxylic acids. These polyol components are prepolymers that are chain-extended with an isocyanate such as 2,4-tolylene diisocyanate (TDI), 1,4 diphenylmethane diisocyanate (MDI), or isophorone diisocyanate (IPDI), if necessary.

  The following can be used as an isocyanate compound to be reacted with these polyol components. Aliphatic polyisocyanates such as ethylene diisocyanate, aliphatic polyisocyanates such as 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), cyclohexane 1,3-diisocyanate, cyclohexane 1,4-diisocyanate, 2,4 -Aromatic isocyanates such as tolylene diisocyanate, 2,6-tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), copolymers thereof, block bodies thereof, and the like.

  The conductive fine particles b) contained in the surface layer 4 are preferably carbon black from the viewpoints of imparting conductivity and reinforcing properties.

  As the properties of the conductive fine particles, carbon black having a primary particle diameter of 18 nm or more and 25 nm or less and a DBP oil absorption of 77 ml / 100 g or more and 160 ml / 100 g or less has a good balance of conductivity, hardness, and dispersibility. Especially preferred. It is preferable that the content rate of electroconductive fine particles is 10 to 25 mass% with respect to 100 mass parts of resin components which form a surface layer. If it is 10% by mass or less, the conductivity of the developing roller may not be in a preferable range. On the other hand, when the amount is 25% by mass or more, the hardness of the surface layer becomes high due to the reinforcing property of the carbon black, stress is applied to the toner, and image defects such as filming may occur.

  The microgel c) contained in the surface layer 4 has a number average particle diameter of 60 nm or more and 100 nm or less, and has a skeleton composed of at least one of methyl methacrylate, styrene, and urethane.

  The “microgel” in the present invention represents internally crosslinked polymer fine particles having an average diameter of 100 nm or less. The microgel has a feature that it can be self-dispersed in an organic solvent or water. Therefore, the microgel particles can hardly be aggregated even in the surface layer and can exist in a uniformly dispersed state. When the developing roller is continuously energized, carbon black aggregates in the surface layer and the conductive path is blocked, so that the resistance increases and image defects such as ghosting may occur. However, when the surface layer 4 contains microgel particles that are present in a uniformly dispersed state, the movement and aggregation of conductive fine particles such as carbon black are suppressed, and an effect of suppressing current deterioration can be expected. The present invention has been found and the present invention has been achieved.

  The number average particle size of the microgel is particularly preferably 60 nm or more and 100 nm or less. When the number average particle diameter is 60 nm or less, the dispersion stability in the medium may be lowered. Moreover, when exceeding 100 nm, the electricity supply deterioration inhibitory effect may fall or the smoothness of a surface may fall.

  It is particularly preferable that the resin component constituting the microgel has a skeleton composed of at least one of methyl methacrylate, styrene, and urethane. A microgel having a methyl methacrylate or styrene skeleton has particularly good self-dispersibility in an organic solvent, and a microgel having a urethane skeleton has a good dispersibility in a weak medium such as water or toluene. Therefore, when a surface layer is formed by applying a paint, a good dispersion state can be maintained in the film of the surface layer, and an excellent energization deterioration suppressing effect can be obtained.

  The glass transition temperature (hereinafter referred to as Tg) of the microgel is preferably 10 ° C. or higher and 60 ° C. or lower. When the temperature is 10 ° C. or lower, the swelling rate in the solvent is remarkably increased, which may cause aggregation or deformation. On the other hand, when the temperature is 60 ° C. or higher, the hardness of the surface layer increases, and image defects such as filming may occur.

  The content of the microgel is preferably 5.0 parts by mass or more and 15.0 parts by mass or less with respect to the binder resin component a) of the surface layer. When the amount is 5.0 parts by mass or less, there may be a case where the effect of suppressing current deterioration is not sufficiently obtained. When the amount is 15.0 parts by mass or more, the hardness of the surface layer may be increased and the image may be affected.

  Further, the microgel can have a functional group such as a hydroxyl group or an amino group on the surface. When it has a functional group capable of forming a chemical bond with such a binder resin component, a higher effect of suppressing current deterioration is obtained, which is particularly preferable.

  The swelling ratio of the microgel with respect to the solvent is preferably 5.0% or more and 25.0% or less with respect to methyl ethyl ketone or toluene. If it is 5.0% or less, the affinity with the resin component is lowered, and the good dispersibility in the surface layer may be lowered. Moreover, when it becomes 25.0% or more, aggregation or deformation may occur in the solvent.

  The swelling ratio of the microgel can be determined as follows. In the case of dry microgel powder, a fixed volume (abbreviated as V1) of particles is immersed in methyl ethyl ketone or toluene, and the swelling volume after 1 hour (abbreviated as V2) is measured using a graduated cylinder, etc. It can be calculated by V2 / V1.

  In the case of a solvent dispersion, after the solvent has been distilled off under reduced pressure in advance, a sufficiently dried sample can be prepared and measured and calculated in the same manner as described above.

  The coefficient of variation C of the particle size distribution on the basis of the number of microgels is represented by C ≦ 1.4% (where C = (Sw / D) × 100, where Sw indicates the standard deviation in the number-based particle size distribution of the particles. , D represents a particle number average particle size (μm)). If the coefficient of variation exceeds 1.4%, the particle size distribution of the microgel becomes large, and the effect of suppressing current deterioration may be reduced.

  When surface roughness is required for the developing roller, fine particles for roughness control may be added to the surface layer 4. The fine particles for roughness control preferably have a volume average particle diameter of 3 μm to 20 μm. Moreover, it is preferable that the particle addition amount added to a surface layer is 1 mass part-50 mass parts with respect to 100 mass parts of resin solid content of a surface layer.

  As the fine particles for roughness control, fine particles of polyurethane resin, polyester resin, polyether resin, polyamide resin, acrylic resin, and polycarbonate resin can be used.

  In the production of the developing roller, the surface layer 4 is formed by mixing a microgel organic solvent dispersion in a resin solution in which conductive fine particles are dispersed and mixed, and then coating the resin layer surface on the outer peripheral surface of the core. Can be done by the method. Although it does not specifically limit as a specific method, The spray by a coating material, immersion, or a roll coat is mentioned. In the dip coating, the method of overflowing the paint from the upper end of the dip tank as described in JP-A-57-5047 is simple and excellent in production stability as a method for forming the surface layer.

  FIG. 4 is a schematic view of a dip coating apparatus. A cylindrical immersion tank 25 has an inner diameter slightly larger than the outer diameter of the developing roller and a depth larger than the axial length of the developing roller. An annular liquid receiving portion is provided on the outer periphery of the upper edge of the immersion tank 25 and is connected to the stirring tank 27. The bottom of the immersion tank 25 is connected to the stirring tank 27.

  The paint in the stirring tank 27 is fed to the bottom of the immersion tank 25 by the liquid feed pump 26. The paint overflows from the upper end of the immersion tank and returns to the agitation tank 27 via the liquid receiving part on the outer periphery of the upper edge of the immersion tank 25. The core body 2 provided with the elastic layer 3 is fixed vertically to the elevating device 28, immersed in the immersion tank 25, and pulled up to form the surface layer 4.

  The process cartridge and the electrophotographic image forming apparatus of the present invention are not limited to copying machines, facsimiles, or printers as long as they have the developing roller of the present invention.

  A printer will be described below as an example of the process cartridge and the electrophotographic image forming apparatus of the present invention equipped with the developing roller of the present invention. In FIG. 6, the developing device 10 includes a developing container that contains a non-magnetic toner 8 as a one-component toner, and a toner that is located in an opening extending in the longitudinal direction in the developing container and that is opposed to the photoconductor 5. And a developing roller 1 for carrying. The developing device 10 visualizes the latent image by developing the electrostatic latent image on the photoconductor 5 to form a toner image.

  The process cartridge is provided with at least the developing roller of the present invention, and has a structure that can be attached to and detached from the electrophotographic image forming apparatus.

  As shown in FIG. 3, the printer is provided with a photoreceptor 5 that is rotated by a rotation mechanism (not shown). Around the photosensitive member 5, a charging member 12 that charges the surface of the photosensitive member 5 to a predetermined polarity and potential, and an electrostatic latent image is formed by performing image exposure on the charged surface of the photosensitive member 5. The illustrated image exposure apparatus is arranged. Further, a developing device 10 having a developing roller 6 according to the present invention is disposed around the photosensitive member 5 for developing the toner by attaching toner onto the formed electrostatic latent image. Further, a device 13 for cleaning the surface of the photoconductor 5 after the toner image is transferred to the paper 22 is provided.

  A fixing device 15 for fixing the transferred toner image on the paper 22 is disposed on the conveyance path of the paper 22.

  Specific examples and comparative examples according to the present invention will be described below.

  In this example, the Tg of the microgel was measured using a scanning calorimeter DSC8230L (manufactured by Rigaku Corporation) as a measuring instrument.

  The number average particle size of the microgel can be a value determined by the following method.

  First, the surface layer is cut out from the developing roller, an ultrathin section is prepared from the cut out surface layer, and used as a sample for observation. Specifically, a diamond knife (trade name: Cryo dry 35 °; Diatom) is used in an atmosphere of −120 ° C. or more and −50 ° C. or less using a section preparation device (Leica Microsystems, Inc .; Leica EM FCS). Is used to produce an ultrathin section having a thickness of about 50 nm. The created observation sample is observed with a TEM. The direct observation magnification is 140,000 times. The photographed film is magnified twice and developed, and finally a 280,000 times photograph is obtained.

  From the photograph, 500 microgel particles are arbitrarily selected and the area equivalent diameter of each microgel particle is determined. If the microgel particles selected arbitrarily overlap with the adjacent microgel particles, the equivalent particle diameter of the microgel particles is not determined and other particles are selected. For any 500 particles, the area equivalent diameter is obtained, and the value obtained by rounding off the first decimal place of the arithmetic average value of the area equivalent diameters of the 500 particles is defined as the number average particle diameter D of the microgel. The standard deviation Sw was calculated from the 500 equivalent area diameters obtained, and (Sw / D) × 100 was defined as the coefficient of variation C.

  The primary particle diameter of carbon black can be a value determined by the following method.

  First, the surface layer is cut out from the developing roller in the same manner as in the above-described measurement of the number average particle diameter of the microgel to obtain a 280,000-fold photograph.

  From the photograph, 500 carbon black particles are arbitrarily selected and the area equivalent diameter (diameter of a circle having an area equal to the projected area) is determined for each carbon black particle. If the carbon black particles selected arbitrarily overlap with the adjacent carbon black particles, the area equivalent diameter of the carbon black particles is not determined and other particles are selected. The determination of whether there is much or little overlap with adjacent carbon black particles will be described with reference to FIG. In FIG. 7, since the central carbon black particle Y is in contact with two adjacent carbon black particles X and Z, the exact contour of the particle Y is unknown. However, carbon black is a substance that easily forms an aggregate (structure), and most of the particles overlap as shown in FIG. As shown in FIG. 8, two points (the points A and B) where the contour lines of the particles Y and X intersect are connected by a straight line. Similarly, for the particles Y and Z, the points C and D are obtained and connected by straight lines to form a closed plane connected by the straight lines AB, BC, CD, and DA. If the sum of the length of the line segment AB and the length of the line segment CD is 20% or less of the sum of the length of the curve AD and the length of the curve BC, the area of the particle Y is defined as an outline, a straight line AB, a curve The area of the closed plane connected by BC, straight line CD, and curve DA is obtained, and the diameter of a circle having a diameter equal to the area is calculated. A value obtained by rounding the first decimal place of the calculated diameter (unit: nm) to an integer is defined as the area equivalent diameter of the particle Y. When the sum of the length of the straight line AB and the length of the straight line CD is larger than 20% of the sum of the length of the curve AD and the length of the curve BC, the approximate accuracy of the area equivalent diameter is deteriorated. select.

  With the above procedure, the area equivalent diameter was determined for any 500 particles, and the value obtained by rounding the first decimal place of the arithmetic mean value of the area equivalent diameters of the 500 particles was defined as the primary particle diameter of carbon black. To do.

  The resistance value of the developing roller is determined by pressing the developing roller at 20 ° C. and 40% RH using a resistance measuring machine shown in FIG. Resistance measurement was performed at a rotational speed of 60 rpm, and an average value for 3 seconds was defined as a roller resistance value.

  The surface hardness of the developing roller was measured with a micro rubber hardness meter MD-1capa (manufactured by Kobunshi Keiki Co., Ltd.) using a 0.16 mm diameter pusher needle at a temperature of 25 ° C. and relative humidity of 50% RH. An average value obtained by measuring three points at the center, upper end, and lower end of the subsequent developing roller was used.

Example 1
As the core body 2, an SUS304 core metal having a diameter of 8 mm was subjected to nickel plating, and a primer [DY35-051 (trade name), manufactured by Toray Dow Corning Silicone Co., Ltd.] was applied and baked. Next, the shaft core body 2 was placed in a mold, and an addition-type silicone rubber composition in which components of the following composition were mixed was injected into a cavity formed in the mold.
(Addition type silicone rubber composition)
・ Liquid silicone rubber material 100.0 parts by mass [SE6724A / B (trade name), manufactured by Toray Dow Corning Silicone Co., Ltd.]
・ 35.0 parts by mass of carbon black [Toka Black # 7360SB (trade name, manufactured by Tokai Carbon Co., Ltd.)]
Silica powder (heat resistance imparting agent) 0.2 parts by mass Platinum catalyst (heat resistance imparting agent) 0.1 parts by mass Subsequently, the mold is heated to cure and cure the silicone rubber at a temperature of 150 ° C. for 15 minutes. After demolding, the resin was further heated at 180 ° C. for 1 hour to complete the curing reaction, and the resin layer 3 was provided on the outer periphery of the shaft core 2.

As the material of the outermost resin layer 4, in the components (A) to (C) in the following composition, (A) was used as a solvent, and component (C) was mixed stepwise with component (B). Then, it was made to react at 80 degreeC by nitrogen atmosphere for 5 hours, and obtained the weight average molecular weight Mw = 11000 and the polyurethane polyol A of the hydroxyl value 26.
(A) 122.0 parts by mass of methyl ethyl ketone (MEK) (B) 100.0 parts by mass of polytetramethylene glycol (trade name; PTG1000SN, manufactured by Hodogaya Chemical Co., Ltd.)
(C) Isocyanate compound for chain extension 22.2 parts by mass (trade name; Cosmonate MDI, manufactured by Mitsui Takeda Chemical Co., Ltd.)
Next, with 100.0 parts by mass of polyurethane polyol A, two components having the following composition are mixed with stirring, dissolved in MEK so that the total solid content ratio is 30% by mass, and then mixed uniformly in a sand mill. The resin solution 1 for resin layer formation was obtained.
-Coronate 2521 (trade name, manufactured by Nippon Polyurethane Industry Co., Ltd.) 26.2 parts by mass-Carbon black SUNBLACKX15 (trade name, manufactured by Asahi Carbon Co., Ltd.) 15.5 parts by mass Further, the microgel MEK dispersion A shown in Table 1 (S -1200, manufactured by Nippon Paint Co., Ltd., solid content of 20% by mass) 16.5 parts by mass were gradually added while stirring with a stirring motor, and further mixed and stirred with a stirring motor for 5 minutes to obtain paint 1 for forming a surface layer.

  Further, this dispersion is diluted with MEK to a viscosity of 7 cps to 10 cps, dip-coated on the elastic layer, dried, and heat-treated at a temperature of 150 ° C. for 1 hour to have a film thickness of about 10 μm on the outer periphery of the elastic layer. A surface layer was provided to obtain the developing roller of Example 1. The surface hardness of the developing roller measured by the above method was 37.0.

(Example 2)
Microgel dispersion A was changed to Microgel dispersion B (S-0597, manufactured by Nippon Paint Co., Ltd., solid content: 25% by mass), and the addition amount was changed to 26.4 parts by mass. Thus, a developing roller of Example 2 was obtained.

(Example 3)
The same as in Example 1 except that the microgel dispersion A was changed to microgel dispersion C (S-1500, manufactured by Nippon Paint Co., Ltd., solid content 25% by mass) and the addition amount was changed to 26.4 parts by mass. Thus, a developing roller of Example 3 was obtained.

Example 4
Microgel dispersion A was changed to microgel dispersion D (S-5004, Nippon Paint Co., Ltd., solid content 20% by mass), and the addition amount was changed to 33.1 parts by mass. Thus, a developing roller of Example 4 was obtained.

(Example 5)
The microgel dispersion A was changed to microgel dispersion E (NAP SERIES, manufactured by Soken Chemical Co., Ltd., solid content: 10% by mass), and the addition amount was changed to 66.0 parts by mass. Thus, a developing roller of Example 5 was obtained.

(Example 6)
A developing roller of Example 6 was obtained in the same manner as in Example 5 except that the addition amount of the microgel dispersion E was changed to 13.2 parts by mass.

(Example 7)
A developing roller of Example 7 was obtained in the same manner as Example 5 except that the addition amount of the microgel dispersion E was changed to 99.9 parts by mass.

(Example 8)
A developing roller of Example 8 was obtained in the same manner as in Example 5 except that the addition amount of the microgel dispersion E was changed to 132.0 parts by mass.

Example 9
A developing roller of Example 9 was obtained in the same manner as in Example 5 except that the microgel dispersion A was changed to microgel MEK dispersion F (NAP SERIES, manufactured by Soken Chemical Co., Ltd., solid content: 10% by mass).

(Example 10)
Each component of (D) to (F) having the following composition was charged into a flask, heated to 120 ° C. with stirring in a nitrogen atmosphere, held for 30 minutes, and then 0.1 part by mass of tin octenoate was added. It was. After further 1 hour, the temperature was lowered to 80 ° C., 500.0 parts by mass of MEK and 20.0 parts by mass of dimethylolpropionic acid were added, and the reaction was allowed to proceed at 75 ° C. for 5 hours.
(D) Plaxel 212 (trade name, manufactured by Daicel Chemical Industries) 122.0 parts by mass (E) Desmophen 1140 (trade name, manufactured by Sumika Bayer Urethane Co., Ltd.) 67.0 parts by mass (F) Isophorone diisocyanate 166.0 parts by mass Subsequently, 200.0 parts by mass of this prepolymer was diluted with 100.0 parts by mass of MEK, and gradually stirred into an aqueous solution consisting of 4.5 parts by mass of triethylamine and 400.0 parts by mass of water. It was thrown into. Thereafter, an aqueous solution in which 2.0 parts by mass of diethylenetetramine was dissolved in 20 parts by mass of water was gradually added. Next, after maintaining at 70 ° C. for 1 hour on an oil bath, MEK was distilled off under reduced pressure to obtain a urethane water dispersion.

  200.0 parts by mass of the urethane water dispersion and 500.0 parts by mass of toluene were charged into a flask equipped with a condenser and a receiver for separating and refluxing water and a solvent. Subsequently, while injecting nitrogen under the liquid surface, the temperature was raised to 100 ° C. to azeotrope water and toluene, and at the same time, the cooling liquid was separated in a receiver, and the toluene was refluxed into the flask to remove the water from the system. Separated and removed. A toluene dispersion G (solid content 20%) of urethane microgel was obtained.

  A developing roller of Example 10 was obtained in the same manner as Example 2 except that the microgel dispersion A was changed to the microgel dispersion G.

(Example 11)
A developing roller of Example 11 was obtained in the same manner as Example 5 except that the carbon black was changed to Color Black S160 (trade name, manufactured by Degussa Japan).

Example 12
A developing roller of Example 12 was obtained in the same manner as Example 5 except that the carbon black was changed to Special Black 6 (trade name, manufactured by Degussa Japan).

(Example 13)
A developing roller of Example 13 was obtained in the same manner as Example 5 except that the carbon black was changed to SUNBLACKX55 (trade name, manufactured by Asahi Carbon Co., Ltd.).

(Example 14)
A developing roller of Example 14 was obtained in the same manner as in Example 5 except that the carbon black was changed to Special Black 350 (trade name, manufactured by Degussa Japan).

(Example 15)
A developing roller of Example 15 was obtained in the same manner as Example 5 except that the carbon black was changed to Printex L6 (trade name, manufactured by Degussa Japan).

(Example 16)
A developing roller of Example 16 was obtained in the same manner as in Example 5 except that the amount of carbon black SUNBLACKX15 (trade name, manufactured by Asahi Carbon Co., Ltd.) was changed to 3.6 parts by mass.

(Example 17)
A developing roller of Example 17 was obtained in the same manner as Example 5 except that the amount of carbon black SUNBLACKX15 (trade name, manufactured by Asahi Carbon Co., Ltd.) was changed to 7.5 parts by mass.

(Example 18)
A developing roller of Example 18 was obtained in the same manner as in Example 5 except that the amount of carbon black SUNBLACKX15 (trade name, manufactured by Asahi Carbon Co., Ltd.) was changed to 18.6 parts by mass.

(Example 19)
A developing roller of Example 19 was obtained in the same manner as in Example 5 except that the amount of carbon black SUNBLACKX15 (trade name, manufactured by Asahi Carbon Co., Ltd.) was changed to 21.8 parts by mass.

(Comparative Example 1)
A developing roller of Comparative Example 1 was obtained in the same manner as Example 1 except that no microgel was added.

(Comparative Example 2)
A developing roller of Comparative Example 2 was obtained in the same manner as in Example 2 except that the microgel dispersion B was changed to the microgel dispersion H (S-0597, manufactured by Nippon Paint Co., Ltd.).

(Comparative Example 3)
A developing roller of Comparative Example 3 was obtained in the same manner as in Example 2 except that the microgel dispersion B was changed to Microgel Dispersion I (S-4000, manufactured by Nippon Paint Co., Ltd.).

(Comparative Example 4)
A developing roller of Comparative Example 4 was obtained in the same manner as in Example 2 except that the microgel B was changed to NBR rubber particles J (VP-401, manufactured by Beijing Chemical Research Laboratory).

(Comparative Example 5)
A developing roller of Comparative Example 5 was obtained in the same manner as in Example 2 except that Microgel B was changed to SBR rubber particles K (VP-121, manufactured by Beijing Chemical Research Laboratory).

(Comparative Example 6)
A developing roller of Comparative Example 6 was obtained in the same manner as in Example 2 except that the microgel B was changed to fine particle barium sulfate BF-21 (trade name, manufactured by Sakai Chemical Industry Co., Ltd.).

(Comparative Example 7)
A developing roller of Comparative Example 7 was obtained in the same manner as in Example 2 except that the microgel B was changed to fine particle titanium oxide TTO-55 (trade name, manufactured by Ishihara Sangyo Co., Ltd.).

  The surface hardness of the developing rollers of Examples 1 to 19 and Comparative Examples 1 to 7 obtained as described above was measured.

The roller appearance was evaluated according to the following criteria.
A: In terms of appearance, no reduction in gloss and rough skin are observed.
B: An extremely slight decrease in gloss is observed.
C: Remarkable gloss reduction and rough skin are observed.

Moreover, after leaving each obtained coating material in a sealed glass bottle at 20 ° C. for 2 days, the stability was evaluated according to the following criteria.
A: No sediment component is observed at the bottom of the glass bottle.
B: Although a sedimentation component is observed at the bottom of the glass bottle, it easily disappears by stirring.
C: A sedimentation component is observed at the bottom of the glass bottle and does not disappear even when stirred.

  Measurement of resistance rise (energization deterioration) during continuous energization was performed as follows. Using a resistance measuring machine shown in FIG. 5 in a 20 ° C., 40% RH environment, with a pressure of 1 kgf (500 gf at each end of the core metal), 100 V applied at a roller rotation speed of 60 rpm, and energized for 1 hour , (Resistance value after energization / initial resistance value) was used as an index of energization deterioration. 2.00 or less is preferable as a standard for the deterioration of energization, and 1.50 or less is more preferable.

  Next, image durability was evaluated about the obtained developing roller. Evaluation of image durability was carried out by loading the developing roller of this example and a comparative example on a modified machine of a Canon laser beam printer (trade name: LBP5500) having the configuration as shown in FIG. As evaluation of image durability, filming amount and ghost were evaluated.

First, 10,000 sheets were continuously printed with a non-magnetic one-component black toner at a printing rate of 2% in an environment where the temperature was 23 ° C. and the relative humidity was 55% RH. After that, as an image pattern, a 15 mm square solid black image is printed on the leading edge within one sheet, and then the entire halftone image is printed. The density unevenness of the developing roller period appearing in the halftone portion is visually evaluated, and the ghost is determined according to the following criteria. It was evaluated with.
A: A ghost is not recognized at all.
B: Extremely slight ghost is recognized.
C: A remarkable ghost is recognized.

Further, the developing roller after the image durability test was taken out, the toner on the surface was removed, the filming state on the surface of the developing roller was observed with an optical microscope, and filming was evaluated according to the following criteria.
A: No filming is observed on the roller surface.
B: Extremely slight filming is observed on the roller surface.
C: Remarkable filming is recognized on the roller surface.

  The above results are shown in Tables 1-3.

  In Examples 1 to 19, the surface layer contains a microgel having a number average particle diameter of 60 nm to 100 nm and having a skeleton composed of at least one of methyl methacrylate, styrene, and urethane. For this reason, the developing roller is a high-quality developing roller that is excellent in conductivity, resistance to electrical deterioration, and flexibility. In particular, the developing rollers of Examples 7 to 9 including an acrylic resin not containing a hydroxyl group have both flexibility and other qualities at a high level.

  In contrast, Comparative Example 1 containing no microgel, Comparative Example 3 having a number average particle diameter exceeding 100 nm, and Comparative Examples 4 to 7 containing rubber and inorganic compound fine powder show an increase in resistance after energization (energization). Deterioration is great). In Comparative Example 2 and Comparative Examples 4 to 7 in which the particle size of the microgel was less than 50 nm, the coating material separated and settled over time, and aggregation of particle components was observed.

It is a conceptual diagram which shows an example of the developing roller of this invention. It is a conceptual diagram which shows the cross section of an example of the developing roller of this invention. 1 is a schematic configuration diagram illustrating an example of an electrophotographic image forming apparatus of the present invention. It is a conceptual diagram which shows an example of a liquid circulation type dip coating apparatus. It is a conceptual diagram which shows an example of resistance measurement. It is a schematic block diagram which shows an example of the process cartridge of this invention. It is explanatory drawing which calculates | requires the area equivalent diameter of the carbon black particle of the surface layer of the image development roller of this invention. It is explanatory drawing which calculates | requires the area equivalent diameter of the carbon black particle of the surface layer of the image development roller of this invention.

Explanation of symbols

1: Developing roller 2: Conductive shaft core 3: Resin layer 4: Surface layer 5: Photoreceptor 6: Cleaning member 7: Toner supply roller 8: Toner 9: Regulator blade 10: Developing device 11: Laser beam 12: Charging Member 13: Cleaning device 14: Cleaning charging device 15: Fixing device 16: Driving roller 17: Transfer roller 18: Bias power source 19: Tension roller 20: Transfer conveyance belt 21: Driven roller 22: Paper 23: Paper feed roller 24: Adsorption roller 25: immersion tank 26: liquid feed pump 27: stirring tank 28: lifting device 29: reference resistance 30: metal drum

Claims (12)

A developing roller having a resin layer on the outer peripheral surface of the core and a surface layer on the outer peripheral surface of the resin layer, wherein the surface layer contains the following a), b) and c): .
a) Binder resin component b) Conductive fine particles c) A microgel having a number average particle diameter of 60 nm to 100 nm and having a skeleton composed of at least one of methyl methacrylate, styrene, and urethane   The developing roller according to claim 1, wherein the glass transition temperature of the microgel is 10 ° C. or more and 60 ° C. or less.   The developing roller according to claim 1, wherein the content of the microgel is 5.0 parts by mass or more and 15.0 parts by mass or less with respect to the surface layer.   The developing roller according to claim 1, wherein the microgel is chemically bonded to the binder resin component.   The developing roller according to claim 1, wherein the swelling ratio of the microgel with respect to methyl ethyl ketone or toluene is 5.0% or more and 25.0% or less.   The coefficient of variation C of the particle size distribution on the basis of the number of microgels is represented by C ≦ 1.4% (where C = (Sw / D) × 100, where Sw is the standard deviation in the number-based particle size distribution of the particles. The developing roller according to claim 1, wherein D is a number average particle diameter (μm) of the particles.   7. The developing roller according to claim 1, wherein the conductive fine particles are carbon black having a primary particle diameter of 18 nm to 25 nm and a DBP oil absorption of 77 ml / 100 g to 160 ml / 100 g.   The developing roller according to claim 1, wherein the content of the conductive fine particles is 10% by mass or more and 25% by mass or less with respect to the binder resin component. In the method for producing a developing roller having a resin layer on the outer peripheral surface of the core body and having a surface layer on the outer peripheral surface of the resin layer,
A method for producing a developing roller, wherein the surface layer is formed by mixing a resin solution in which conductive fine particles are dispersed and mixed with an organic solvent dispersion of microgel and then applying the mixture to the surface of the resin layer. . In a developing device for visualizing a latent image by applying a toner to a photosensitive member carrying a latent image, the container having toner and a developing roller for carrying the toner.
A developing device, wherein the developing roller is the developing roller according to claim 1. In a process cartridge that is equipped with at least a developing roller and is detachable from an electrophotographic image forming apparatus.
9. A process cartridge using the developing roller according to claim 1 as the developing roller. In an electrophotographic image forming apparatus, comprising: a developing roller that carries toner in a state of being opposed to a photosensitive member that carries a latent image, wherein the developing roller develops the latent image by applying toner to the photosensitive member.
An electrophotographic image forming apparatus comprising the developing roller according to claim 1.

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