JP4194512B2 - Developing roller, electrophotographic process cartridge, and electrophotographic image forming apparatus - Google Patents

Description

  The present invention relates to a developing roller used in an electrophotographic apparatus such as a copying machine or a laser printer, and an electrophotographic process cartridge and an electrophotographic image forming apparatus using the developing roller.

  Conventionally, in an electrophotographic apparatus such as a copying machine or a laser printer or an electrostatic recording apparatus, a non-magnetic one-component developer is supplied to a photosensitive drum or the like holding a latent image, and the developer is attached to the latent image on the photosensitive drum. A pressure development method is known as a development method for visualizing the latent image. According to this method, since no magnetic material is required, the image forming apparatus can be easily simplified and downsized, and the toner can be easily colored. In this developing method, a developing roller carrying toner (non-magnetic one-component developer) is brought into contact with a latent image holding body holding an electrostatic latent image such as a photosensitive drum, and the toner is transferred to the latent image of the latent image holding body. Therefore, it is necessary to form the developing roller with a conductive elastic body. This method of developing the toner in contact with the photosensitive drum requires the uniformity of the toner layer on the developing roller and the toner charging uniformity.

  However, in recent years, the accuracy required for the developing roller has become stricter with the increase in the speed of the printer body and the lowering of the melting point of the toner. As one of the problems, drum contamination with toner, which has not occurred in the past, has become a problem because of the high speed of the main body process and the low melting point of the toner. This drum contamination is caused by the stress applied to the toner between the developing roller and the photosensitive drum, so that when the number of printed sheets increases, the external additive of the toner is peeled off or the toner base is deformed.

As a countermeasure against this, as described in Patent Document 1, a technique for reducing the friction coefficient of the roller surface in order to reduce stress on the toner is known.
JP 2003-255893 A

  However, in the technique of Patent Document 1, drum contamination may still occur, and it may not be possible to reduce the friction coefficient in the macro friction measurement method.

  An object of the present invention is to provide a high-performance developing roller that does not cause drum contamination due to toner as described above.

  According to the present invention, as a result of intensive studies to achieve the above object, by controlling the micro friction degree on the surface of the developing roller, the toner external additives can be peeled off due to the contact friction between the individual toner and the roller surface, It has been found that deformation can be prevented and drum contamination with toner can be prevented. The present invention has been achieved based on such findings.

That is, the present invention includes a mandrel, and provided on the the mandrel conductive elastic layer, and have a conductive resin layer constituting the outermost layer, the conductive resin layer, 2 A urethane resin raw material mixture containing an isocyanate compound and a linear polyurethane polyol prepolymer obtained by chain-extending a functional polyol (a) and a bifunctional isocyanate compound (b) in an amount of 70 to 95% by mass is cured. A developing roller containing a urethane resin obtained in this manner, wherein the microfriction degree μ in the developing region on the surface of the developing roller is 300 ≦ μ ≦ 2000. The developing area on the surface of the developing roller refers to a portion of the developing roller surface that comes into contact with an area where a latent image exists on the photosensitive drum.
Here, a shaft core body, a conductive elastic layer provided on the shaft core body, and a conductive resin layer constituting the outermost layer, the microfriction degree μ of the surface in the development region of the outermost layer As a method for producing a developing roller having a thickness of 300 to 2000,
(I) A linear polyurethane obtained by extending a chain of a bifunctional polyol (a) and a bifunctional isocyanate compound (b), having a weight average molecular weight of 10,000 to 50,000 and a molecular weight dispersity of Mz / Mw = 2.5 or less. A step of curing a urethane resin raw material mixture containing 70 to 95% by mass of a polyol prepolymer, an isocyanate compound, and a conductive material on the peripheral surface of the conductive elastic layer to obtain a urethane resin layer;
(Ii) heat-treating the urethane resin layer at a temperature of 130 ° C. or higher and 180 ° C. or lower for 1 hour to 24 hours;
A method having

  The present invention further relates to an electrophotographic process cartridge having the developing roller.

  The present invention further includes a developing roller for forming a toner thin film by carrying toner on the surface, and in this state, contacting the latent image carrier and supplying the toner to the latent image carrier for visualization. The present invention relates to an electrophotographic image forming apparatus, wherein the developing roller is the developing roller.

  According to the developing roller of the present invention, it is possible to effectively prevent drum contamination due to toner, and by using this, it is possible to obtain a high-quality image.

  Hereinafter, the present invention will be described in more detail.

  As shown in FIG. 1, the developing roller of the present invention has a conductive elastic layer 2 on the outer periphery of a shaft core body 1, and this conductive elastic layer 2 is covered with a conductive resin layer 3 made of a conductive resin. Is formed. The conductive elastic layer 2 and the conductive resin layer 3 may be any number of layers, but at least the microfriction degree in the development region on the surface of the conductive resin layer of the outermost layer is adjusted to a range of 300 ≦ μ ≦ 2000. It is. More preferably, 500 ≦ μ ≦ 1200.

  The microfriction can be derived by the following measurement.

  The micro-friction on the surface of the developing roller is measured by cutting a portion to be a developing area on the surface of the developing roller into 3 mm squares, fixing the sample table with an adhesive, and using an AFM of a scanning probe microscope SPA400 (trade name, manufactured by Seiko Instruments). The measurement was performed in the FFM measurement mode. The cantilever was SI-AF01. The measurement conditions were a scanning range of 2 μm × 2 μm, a rotation angle of 90 °, and a measurement data number of 256 × 256. The average of 256 × 256 numerical values of the obtained friction image was obtained, and this value was defined as the microfriction degree. The 10-point average of the microfriction obtained thereby was defined as the microfriction.

  The microfriction obtained thereby reflects the surface characteristics of the developing roller in a very small region, unlike the conventional macro friction measurement method. According to the conventional macroscopic friction measurement, the measured value greatly depends on factors such as the surface shape of the roller and dirt that are not originally related to the contact between the toner and the roller surface, and the true roller surface characteristics cannot be obtained. There were drawbacks. However, according to the microfriction degree related to the present invention, it has been found that the difference in surface characteristics can be clarified even with a developing roller that did not show a difference in the conventional friction measurement method. That is, by controlling the microfriction degree to an appropriate range, the frictional behavior of the roller surface and the toner or the roller surface and the toner external additive in a very small region can be controlled. By doing so, it was possible to control the durability deterioration of individual toners and succeeded in establishing a technique for preventing drum contamination caused by the toner caused by the deteriorated toner.

  Any material can be used as the shaft core 1 as long as it has good conductivity, but usually a metal cylindrical body having an outer diameter of 4 to 10 mm made of aluminum, iron, SUS or the like is used. It is done.

The conductive elastic layer 2 formed on the outer periphery of the shaft core 1 uses an elastomer such as EPDM or urethane, a foam material, or another resin molded body as a base material, and carbon black, metal, metal oxide or the like. In addition, an electronic conductive material or an ionic conductive material such as sodium perchlorate is blended and an appropriate resistance region is adjusted to 10 ³ to 10 ¹⁰ Ωcm, preferably 10 ⁴ to 10 ⁸ Ωcm. The thickness of the conductive elastic layer is preferably adjusted to 1 mm to 10 mm. At this time, the hardness of the conductive elastic layer is preferably ASKER-C hardness of 25 to 60 °. By setting the ASKER-C hardness to 25 ° or more, deformation due to contact of the developing blade and the drum is less likely to occur, and a horizontal streak that lowers a high-quality image is less likely to occur. Further, by setting the ASKER-C hardness to 60 ° or less, the toner is less likely to be fused to the surface of the developing roller. The ASKER-C hardness is a hardness measured using an ASKER-C type spring type rubber hardness meter (trade name, manufactured by Kobunshi Keiki Co., Ltd.) in accordance with the Japan Rubber Association standard SRIS0101, normal temperature and normal humidity (23 ° C. , 55% RH) with respect to a roller that has been left for 5 hours or longer, the measured value is 30 seconds after the hardness meter is brought into contact with the center of the roller with a force of 1 kg.

  Specific examples of the base material include polyurethane, natural rubber, butyl rubber, nitrile rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber, styrene-butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, chloroprene rubber, and acrylic rubber. , And mixtures thereof, preferably, silicone rubber and EPDM are used.

  Examples of the electronic conductive material used to impart conductivity to the conductive elastic layer 2 include conductive carbon such as ketjen black EC and acetylene black, SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT. Examples include carbon for rubber such as carbon for color (ink) subjected to oxidation treatment, metals such as copper, silver, germanium, and metal oxides. Of these, carbon black, whose conductivity is easily controlled with a small amount, is preferably used. These conductive powders are usually suitably used in the range of 0.5 to 50 parts by mass, particularly 1 to 30 parts by mass with respect to 100 parts by mass of the base material.

  Examples of ionic conductive materials include inorganic ionic conductive materials such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride, and organic ionic conductive materials such as modified aliphatic dimethylammonium ethosulphate and stearyl ammonium acetate. Etc. are used.

  Examples of the resin used for the conductive resin layer 3 include polyamide resin, urethane resin, urea resin, imide resin, melamine resin, fluorine resin, phenol resin, alkyd resin, silicone resin, polyester resin, polyether resin, and mixtures thereof. Be listed. These resins can be used alone or in combination of two or more as required.

  When the conductive resin layer 3 is formed using the urethane resin (I), the urethane resin (I) is preferable because it has a large ability to charge the toner by friction and has wear resistance. At this time, it is preferable to control the microfriction degree μ in the developing region on the surface of the developing roller so that 500 ≦ μ ≦ 1200.

Further, when the urethane resin (I) is used for the conductive resin layer 3, it is obtained by polymerizing the polyurethane polyol prepolymer (A) and the isocyanate compound (B), and the polyurethane polyol prepolymer (A) A linear polyurethane polyol prepolymer obtained by extending a chain of a bifunctional polyol (a) and a bifunctional isocyanate compound (b), having a weight average molecular weight of 10,000 to 50,000 and a molecular weight dispersity of Mz / Mw = 2.5 or less. It is a polymer (A ¹ ), and the linear polyurethane polyol prepolymer (A ¹ ) is preferably contained in the raw material mixture forming the urethane resin (I) in a range of 70 to 95% by mass.

As the polyurethane polyol prepolymer (A), it is preferable to use a bifunctional linear polyurethane polyol prepolymer (A ¹ ) chain-extended with a bifunctional polyol (a) and a bifunctional isocyanate compound (b). The bifunctional linear polyurethane polyol prepolymer (A ¹ ) produced here reacts with the polyfunctional isocyanate compound (B) (including the terminal isocyanate type prepolymer) to form a final form (urethane resin (I)). Thus, the molecular weight between crosslinks (distance between crosslinks) is determined.

  Examples of the bifunctional polyol (a) include ethylene glycol, diethylene glycol, triethylene glycol, polytetramethylene glycol, polypropylene glycol, polyethylene glycol, polyester glycols, polyacetal glycol, polycarbonate glycol, polybutadiene glycol, butylene glycol, and neopentyl glycol. Diols and the like can be used, but polyether polyols having strong molecular crystallinity are preferred. The weight average molecular weight (Mw) of the bifunctional polyol (a) is preferably about 500 to 5000, and more preferably about 500 to 3000. If it is 5000 or less, the proportion of the soft segment in the urethane chain is not too high, and the material strength can be maintained without extremely softening the material. Therefore, it is suitable as a material for the conductive resin layer of the developing roller. .

  Examples of the bifunctional isocyanate compound (b) include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and phenylene diisocyanate. (PPDI), xylene diisocyanate (XDI), tetramethylxylene diisocyanate (TMXDI), cyclohexane diisocyanate and the like. Among these, aromatic isocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), phenylene diisocyanate (PPDI), xylene diisocyanate (XDI), and tetramethylxylene diisocyanate (TMXDI). Compounds are preferred.

The weight average molecular weight (Mw) of the linear polyurethane polyol prepolymer (A ¹ ) is preferably in the range of 10,000 to 50,000. By setting it within this range, the amount of residual deformation with respect to stress is reduced, and image adverse effects such as horizontal stripes due to blade contact traces are less likely to occur. The weight average molecular weight is more preferably 10,000 to 40,000, and more preferably 10,000 to 30,000.

As the molecular weight dispersion of the linear polyurethane polyol prepolymer (A ¹ ), Mw: weight average molecular weight, Mz: Z average molecular weight are used. The Z average molecular weight is most important for the contribution of the high molecular weight compound to the average molecular weight, and is defined as follows.

When there are Ni molecules having a molecular weight Mi in the polymer, it is expressed by the following formula: Mz = (ΣMi ³ Ni) / (ΣMi ² Ni)
The Mz / Mw is preferably 2.5 or less. More preferably, Mz / Mw is 2.0 or less. By setting Mz / Mw to 2.5 or less, changes in the mechanical properties of the material due to environmental changes can be reduced, and no horizontal streaking due to blade contact traces occurs.

The content of the urethane resin linear polyurethane polyol prepolymer in the raw material mixture to form a (I) (A ¹⁾ is preferably from 70 to 95 wt%, more preferably more 75 to 90 wt% . When the content is within these ranges, a developing roller having low hardness and excellent toner transportability can be obtained.

  At this time, it is preferable to set the MD1 hardness of the developing roller conductive resin layer to 25 to 50 ° because the effect of the present invention is promoted. More preferably, it is 30 to 50 °. MD1 hardness can be measured with a micro hardness meter MD1 type (trade name) manufactured by Kobunshi Keiki Co., Ltd. on any surface of a roller left in an environment of normal temperature and normal humidity (23 ° C., 55% RH) for 5 hours or more. The average value of 10-point measurement was defined as MD1 hardness.

  Examples of the electronic conductive material used for imparting conductivity to the conductive resin layer 3 include conductive carbon such as ketjen black EC and acetylene black, SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT. Examples thereof include carbon for rubber such as carbon for carbon (ink) subjected to oxidation treatment, metal such as copper, silver, germanium, and metal oxide. Of these, carbon black, whose conductivity is easily controlled with a small amount, is preferably used.

  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 dimethylammonium ethosulphate and stearyl ammonium acetate. A conductive material is used.

Moreover, in formation of the conductive resin layer 3, when the resin component is 100 parts by mass, a conductive material such as the above-described electronic conductive material or ionic conductive substance is blended at a ratio of 1 to 50 parts by mass. It is preferable. Regarding the kneading of the resin and the conductive material, for example, a roll kneader, a Banbury mixer, a ball mill, a sand grinder, a paint shaker or the like is used for mixing and stirring to form a developing roller surface roughness as needed. After the particles are added and dispersed, a curing agent or a curing catalyst is added, and a paint obtained by stirring is applied by a method such as air spray, roll coating, curtain coating, or dipping. The thickness of the conductive resin layer is preferably 1.0 to 30 μm, and more preferably 3.0 to 20 μm. Further, the conductive resin layer is preferably adjusted to a resistance region of 10 ³ to 10 ⁸ Ωcm, preferably 10 ⁴ to 10 ⁷ Ωcm.

  Examples of the roughening 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. The average particle diameter of the roughened particles is preferably 1.0 to 30 μm. At this time, the surface roughness Rz of the developing roller is generally adjusted to 1 to 15 μm, more preferably 3 to 10 μm. At this time, the surface roughness of the roller is Rz according to JIS B0601: 2001.

  After applying the conductive resin layer, the surface resin is cured at an appropriate curing temperature to complete the developing roller. In the present invention, it is preferable that the developing roller is further heat-treated at an appropriate temperature thereafter. By this heat treatment, the molecular structure of the resin of the conductive resin layer is rearranged so that the desired surface microfriction can be effectively controlled. This heat treatment is preferably carried out for a treatment temperature of 50 to 180 ° C. and a treatment time of 1 to 24 hours, although optimum conditions differ depending on the resin component used.

  As described above, in the developing roller having the shaft core body, the conductive elastic layer provided on the shaft core body, and the conductive resin layer constituting the outermost layer, the microfriction degree μ in the developing region on the surface of the developing roller. Thus, a developing roller characterized in that 300 ≦ μ ≦ 2000 is obtained.

  The present invention further relates to an electrophotographic process cartridge having the developing roller. In the electrophotographic process cartridge, for example, the developing roller 4, the photosensitive drum 5, the toner application roller 6, the developing blade 7, the charging roller 8 and the cleaning blade 9 in the following electrophotographic image forming apparatus are configured in a cartridge form. It is detachable from the electrophotographic image forming apparatus. By using the developing roller of the present invention as the developing roller of the electrophotographic process cartridge, it can be easily attached to and detached from the electrophotographic image forming apparatus, and a high-quality image can be obtained by the electrophotographic image forming apparatus. It becomes.

  The present invention also relates to an electrophotographic image forming apparatus having the developing roller. As shown in FIG. 2, the electrophotographic image forming apparatus includes a toner application roller 6 for supplying toner, a charging roller 8 for charging the photosensitive drum 5, and a toner corresponding to the photosensitive drum 5 holding an electrostatic latent image. It consists of a developing roller 4 for forming an image. A toner is supplied to the surface of the developing roller 4 by the toner application roller 6 and a developing blade 7 for adjusting the toner into a more uniform thin layer. In this state, the developing roller 4 rotates while contacting or approaching the photosensitive drum 5. As a result, the toner formed in a thin layer adheres to the latent image on the photosensitive drum 5 from the developing roller 4 so that the latent image is visualized. The latent image is transferred to a recording medium such as paper between the transfer roller 10 and the photosensitive drum 5, and the toner remaining on the surface of the photosensitive drum 5 after transfer is removed by the cleaning blade 9. It is supposed to be. The recording medium to which the toner has adhered passes through the fixing roller 11 so that the toner can be fixed to the recording medium such as paper by heat and pressure. By using the developing roller of the present invention as the developing roller of the electrophotographic image forming apparatus, a high-quality image can be obtained.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, a present Example does not limit this invention at all.

(Example 1)
A core metal (shaft core) having an outer diameter of 8 mm is placed concentrically in a cylindrical mold having an inner diameter of 16 mm. (C hardness: 40 °, volume resistivity: 10 ⁷ Ω · cm product), put into an oven at 130 ° C, heat-molded for 20 minutes, demolded, and then secondary vulcanized in an oven at 200 ° C for 4 hours. The conductive elastic layer having a thickness of 4 mm was formed.

As a material of the conductive resin layer, polytetramethylene glycol (bifunctional polyol (a), trade name: PTG1000SN; molecular weight Mn = 1000, f = 2 (f represents the number of functional groups); manufactured by Hodogaya Chemical Co., Ltd.) 100 18.7 parts by mass of a bifunctional isocyanate compound (b) (trade name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) is mixed stepwise in a MEK solvent to a part by mass, and a nitrogen atmosphere The mixture was reacted at 80 ° C. for 3 hours to obtain a bifunctional linear polyurethane polyol prepolymer (A ¹ ) having a molecular weight Mw = 10000, a hydroxyl value 18.2 and a molecular weight dispersity Mz / Mw = 1.6. .

100 parts by mass of the above linear polyurethane polyol prepolymer (A ¹ ) and isocyanate compound (B) (trade name: Takenate B830; TMP-modified TDI, equivalent to f (average functional group number) = 3; manufactured by Mitsui Takeda Chemical Co., Ltd.) 5 Further, 3 parts by mass were added, and 15 parts by mass of carbon black (trade name: printtex 35; manufactured by Degussa) was added to adjust the resistance value. 10 parts by mass of acrylic resin particles (trade name: MBX-12; φ12 μm; manufactured by Sekisui Plastics Kogyo Co., Ltd.) were added to the above raw material mixed solution, and uniformly dispersed and mixed to obtain a raw material solution for the conductive resin layer.

  In the raw material liquid for the conductive resin layer, the shaft core body after the formation of the conductive elastic layer is immersed, and after coating the outer surface of the conductive elastic layer with the raw material liquid for the conductive resin layer, Pulled up to dry naturally. Next, the raw material of the coated conductive resin layer was cured by heat treatment at 140 ° C. for 60 minutes. Further, heat treatment was then performed at a temperature of 130 ° C. for 1 hour to obtain a developing roller.

  The resulting developing roller had an MD1 hardness of 30 ° and a microfriction μ of 300.

(Example 2)
The developing roller was coated with a conductive resin layer by the following procedure using a conductive elastic layer having the same composition and thickness as the developing roller produced in Example 1 on the shaft core. Produced.

As a material for the conductive resin layer, polytetramethylene glycol (bifunctional polyol (a), trade name: PTG1000SN; molecular weight Mn = 1000, f = 2; manufactured by Hodogaya Chemical Co., Ltd.) 100 parts by mass is a bifunctional isocyanate compound. (B) (trade name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) 21.5 parts by mass are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 6 hours in a nitrogen atmosphere. Thus, a bifunctional linear polyurethane polyol prepolymer (A ¹ ) having a molecular weight Mw = 50000, a hydroxyl value of 5.4, and a molecular weight dispersity Mz / Mw = 2.5 was obtained.

100 parts by mass of the above linear polyurethane polyol prepolymer (A ¹ ) and isocyanate compound (B) (trade name: Coronate 2521; urethane-modified MDI, f (average functional group number) = 3.8 equivalent; manufactured by Nippon Polyurethane Co., Ltd.) After adding 25 parts by mass, 15 parts by mass of carbon black (trade name: printtex 35; manufactured by Degussa) was added to adjust the resistance value. 10 parts by mass of acrylic resin particles (trade name: MBX-12; φ12 μm; manufactured by Sekisui Plastics Kogyo Co., Ltd.) were added to the above raw material mixed solution, and uniformly dispersed and mixed to obtain a raw material solution for the conductive resin layer.

  In the raw material liquid for the conductive resin layer, the shaft core body after the formation of the conductive elastic layer is immersed, and after coating the outer surface of the conductive elastic layer with the raw material liquid for the conductive resin layer, Pulled up to dry naturally. Next, the raw material of the coated conductive resin layer was cured by heat treatment at 140 ° C. for 60 minutes. Further, heat treatment was then performed at a temperature of 130 ° C. for 1 hour to obtain a developing roller.

  The obtained developing roller had an MD1 hardness of 25 ° and a microfriction μ of 1200.

(Example 3)
Using a conductive elastic layer having the same composition and layer thickness as the developing roller produced in Example 1 on the shaft core, the conductive resin layer was coated and formed in the following procedure. Produced.

As a material for the conductive resin layer, polytetramethylene glycol (bifunctional polyol (a), trade name: PTG1000SN; molecular weight Mn = 1000, f = 2; manufactured by Hodogaya Chemical Co., Ltd.) 100 parts by mass is a bifunctional isocyanate compound. (B) (Trade name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) 19.9 parts by mass of MEK solvent was mixed stepwise and reacted at 80 ° C. for 3 hours in a nitrogen atmosphere. Thus, a bifunctional linear polyurethane polyol prepolymer (A ¹ ) having a molecular weight Mw = 30000, a hydroxyl value 8.4, and a molecular weight dispersity Mz / Mw = 1.9 was obtained.

100 parts by mass of the above linear polyurethane polyol prepolymer (A ¹ ) and isocyanate compound (B) (trade name: Takenate B830; TMP-modified TDI, equivalent to f (average functional group number) = 3; manufactured by Mitsui Takeda Chemical Co., Ltd.) 10 Further, 8 parts by mass was added, and 15 parts by mass of carbon black (trade name: printtex 35; manufactured by Degussa) was added to adjust the resistance value. 10 parts by mass of acrylic resin particles (trade name: MBX-12; φ12 μm; manufactured by Sekisui Plastics Kogyo Co., Ltd.) were added to the above raw material mixed solution, and uniformly dispersed and mixed to obtain a raw material solution for the conductive resin layer.

  In the raw material liquid for the conductive resin layer, the shaft core body after the formation of the conductive elastic layer is immersed, and after coating the outer surface of the conductive elastic layer with the raw material liquid for the conductive resin layer, Pulled up to dry naturally. Next, the raw material of the coated conductive resin layer was cured by heat treatment at 140 ° C. for 60 minutes. Further, heat treatment was performed at a temperature of 130 ° C. for 1 hour to obtain a developing roller.

  The obtained developing roller had an MD1 hardness of 33 ° and a microfriction μ of 1500.

(Example 4)
Using a conductive elastic layer having the same composition and layer thickness as the developing roller produced in Example 1 on the shaft core, the conductive resin layer was coated and formed in the following procedure. Produced.

As a material for the conductive resin layer, polytetramethylene glycol (bifunctional polyol (a), trade name: PTG1000SN; molecular weight Mn = 1000, f = 2; manufactured by Hodogaya Chemical Co., Ltd.) 100 parts by mass is a bifunctional isocyanate compound. (B) (Trade name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) 19.9 parts by mass of MEK solvent was mixed stepwise and reacted at 80 ° C. for 3 hours in a nitrogen atmosphere. Thus, a bifunctional linear polyurethane polyol prepolymer (A ¹ ) having a molecular weight Mw = 30000, a hydroxyl value 8.4, and a molecular weight dispersity Mz / Mw = 1.9 was obtained.

100 parts by mass of the above linear polyurethane polyol prepolymer (A ¹ ) and isocyanate compound (B) (trade name: Takenate B830; TMP-modified TDI, equivalent to f (average functional group number) = 3; manufactured by Mitsui Takeda Chemical Co., Ltd.) 7 Further, 5 parts by mass was added, and 15 parts by mass of carbon black (trade name: printtex 35; manufactured by Degussa) was added to adjust the resistance value. 10 parts by mass of acrylic resin particles (trade name: MBX-12; φ12 μm; manufactured by Sekisui Plastics Kogyo Co., Ltd.) were added to the above raw material mixed solution, and uniformly dispersed and mixed to obtain a raw material solution for the conductive resin layer.

  In the raw material liquid for the conductive resin layer, the shaft core body after the formation of the conductive elastic layer is immersed, and after coating the outer surface of the conductive elastic layer with the raw material liquid for the conductive resin layer, Pulled up to dry naturally. Next, the raw material of the coated conductive resin layer was cured by heat treatment at 140 ° C. for 60 minutes. Further, heat treatment was performed at a temperature of 130 ° C. for 3 hours to obtain a developing roller.

  The resulting developing roller had an MD1 hardness of 30 ° and a microfriction μ of 600.

(Example 5)
Using a conductive elastic layer having the same composition and layer thickness as the developing roller produced in Example 1 on the shaft core, the conductive resin layer was coated and formed in the following procedure. Produced.

As a material for the conductive resin layer, polytetramethylene glycol (bifunctional polyol (a), trade name: PTG1000SN; molecular weight Mn = 1000, f = 2; manufactured by Hodogaya Chemical Co., Ltd.) 100 parts by mass is a bifunctional isocyanate compound. (B) (Trade name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) 19.9 parts by mass of MEK solvent was mixed stepwise and reacted at 80 ° C. for 3 hours in a nitrogen atmosphere. Thus, a bifunctional linear polyurethane polyol prepolymer (A ¹ ) having a molecular weight Mw = 30000, a hydroxyl value 8.4, and a molecular weight dispersity Mz / Mw = 1.9 was obtained.

100 parts by mass of the above linear polyurethane polyol prepolymer (A ¹ ) and isocyanate compound (B) (trade name: Takenate B830; TMP-modified TDI, equivalent to f (average functional group number) = 3; manufactured by Mitsui Takeda Chemical Co., Ltd.) 42 .8 parts by mass was added, and 15 parts by mass of carbon black (trade name: printtex 35; manufactured by Degussa) was added to adjust the resistance value. 10 parts by mass of acrylic resin particles (trade name: MBX-12; φ12 μm; manufactured by Sekisui Plastics Kogyo Co., Ltd.) were added to the above raw material mixed solution, and uniformly dispersed and mixed to obtain a raw material solution for the conductive resin layer.

  In the raw material liquid for the conductive resin layer, the shaft core body after the formation of the conductive elastic layer is immersed, and after coating the outer surface of the conductive elastic layer with the raw material liquid for the conductive resin layer, Pulled up to dry naturally. Next, the raw material of the coated conductive resin layer was cured by heat treatment at 140 ° C. for 60 minutes. Further, a heat treatment was performed at 140 ° C. for 2 hours to obtain a developing roller.

  The resulting developing roller had an MD1 hardness of 50 ° and a microfriction μ of 500.

(Example 6)
Using a conductive elastic layer having the same composition and layer thickness as the developing roller produced in Example 1 on the shaft core, the conductive resin layer was coated and formed in the following procedure. Produced.

As a material for the conductive resin layer, polytetramethylene glycol (bifunctional polyol (a), trade name: PTG1000SN; molecular weight Mn = 1000, f = 2; manufactured by Hodogaya Chemical Co., Ltd.) 100 parts by mass is a bifunctional isocyanate compound. (B) (trade name: Millionate MT; MDI, f = 2; manufactured by Nippon Polyurethane Industry Co., Ltd.) 21.5 parts by mass are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 6 hours in a nitrogen atmosphere. Thus, a bifunctional linear polyurethane polyol prepolymer (A ¹ ) having a molecular weight Mw = 50000, a hydroxyl value of 5.4, and a molecular weight dispersity Mz / Mw = 2.5 was obtained.

100 parts by mass of the above linear polyurethane polyol prepolymer (A ¹ ) and isocyanate compound (B) (trade name: Takenate B830; TMP-modified TDI, equivalent to f (average functional group number) = 3; manufactured by Mitsui Takeda Chemical Co., Ltd.) 10 Further, 8 parts by mass was added, and 15 parts by mass of carbon black (trade name: printtex 35; manufactured by Degussa) was added to adjust the resistance value. 10 parts by mass of acrylic resin particles (trade name: MBX-12; φ12 μm; manufactured by Sekisui Plastics Kogyo Co., Ltd.) were added to the above raw material mixed solution, and uniformly dispersed and mixed to obtain a raw material solution for the conductive resin layer.

  In the raw material liquid for the conductive resin layer, the shaft core body after the formation of the conductive elastic layer is immersed, and after coating the outer surface of the conductive elastic layer with the raw material liquid for the conductive resin layer, Pulled up to dry naturally. Subsequently, the raw material of the coated conductive resin layer was cured by heat treatment at 140 ° C. for 60 minutes to obtain a developing roller.

  The resulting developing roller had an MD1 hardness of 30 ° and a microfriction μ of 2000.

(Comparative Example 1)
Using a conductive elastic layer having the same composition and layer thickness as the developing roller produced in Example 1 on the shaft core, the conductive resin layer was coated and formed in the following procedure. Produced.

As a material for the conductive resin layer, polytetramethylene glycol (bifunctional polyol (a), trade name: PTG1000SN; molecular weight Mn = 1000; f = 2; manufactured by Hodogaya Chemical Co., Ltd.) 100 parts by mass is a bifunctional isocyanate compound. (B) (Product 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 3 hours in a nitrogen atmosphere. Thus, a bifunctional linear polyurethane polyol prepolymer (A ¹ ) having a molecular weight Mw = 60000, a hydroxyl value of 5.3, and a molecular weight dispersity Mz / Mw = 2.4 was obtained.

100 parts by mass of the above linear polyurethane polyol prepolymer (A ¹ ) and isocyanate compound (B) (trade name: Coronate 2521; urethane-modified MDI, f (average functional group number) = 3.8 equivalent; manufactured by Nippon Polyurethane Co., Ltd.) 17.6 parts by mass was added, and 15 parts by mass of carbon black (trade name: printtex 35; manufactured by Degussa) was added to adjust the resistance value. 10 parts by mass of acrylic resin particles (trade name: MBX-12; φ12 μm; manufactured by Sekisui Plastics Kogyo Co., Ltd.) were added to the above raw material mixed solution, and uniformly dispersed and mixed to obtain a raw material solution for the conductive resin layer.

  In the raw material liquid for the conductive resin layer, the shaft core body after the formation of the conductive elastic layer is immersed, and after coating the outer surface of the conductive elastic layer with the raw material liquid for the conductive resin layer, Pulled up to dry naturally. Then, the raw material of the coated conductive resin layer was cured by heat treatment at 140 ° C. for 60 minutes to obtain a developing roller.

  The obtained developing roller had an MD1 hardness of 28 ° and a microfriction of μ of 2100.

(Comparative Example 2)
Using a conductive elastic layer having the same composition and layer thickness as the developing roller produced in Example 1 on the shaft core, the conductive resin layer was coated and formed in the following procedure. Produced.

As a material for the conductive resin layer, polytetramethylene glycol (bifunctional polyol (a), trade name: PTG1000SN; molecular weight Mn = 1000, f = 2; manufactured by Hodogaya Chemical Co., Ltd.) 100 parts by mass is a bifunctional isocyanate compound. (B) (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. Thus, a bifunctional linear polyurethane polyol prepolymer (A ¹ ) having a molecular weight Mw = 7000, a hydroxyl value of 22.6, and a molecular weight dispersity Mz / Mw = 1.4 was obtained.

100 parts by mass of the above-mentioned linear polyurethane polyol prepolymer (A ¹ ) and isocyanate compound (B) (trade name: Takenate B830; TMP-modified TDI, equivalent to f (average functional group number) = 3; manufactured by Mitsui Takeda Chemical Co., Ltd.) 29 0.0 parts by mass was added, and 15 parts by mass of carbon black (trade name: printtex 35; manufactured by Degussa) was added to adjust the resistance value. 10 parts by mass of acrylic resin particles (trade name: MBX-12; φ12 μm; manufactured by Sekisui Plastics Kogyo Co., Ltd.) were added to the above raw material mixed solution, and uniformly dispersed and mixed to obtain a raw material solution for the conductive resin layer.

  In the raw material liquid for the conductive resin layer, the shaft core body after the formation of the conductive elastic layer is immersed, and after coating the outer surface of the conductive elastic layer with the raw material liquid for the conductive resin layer, Pulled up to dry naturally. Then, the raw material of the coated conductive resin layer was cured by heat treatment at 140 ° C. for 60 minutes to obtain a developing roller.

  The obtained developing roller had an MD1 hardness of 40 ° and a microfriction degree μ of 200.

<Image evaluation>
The developing roller was mounted on an electrophotographic process cartridge, and a color laser printer (manufactured by Canon Inc., trade name: LBP5500) was actually printed out to evaluate the image. As the toner used, magenta toner having a number average particle diameter of about 7.0 μm was used.

(Drum contamination evaluation with toner)
The drum contamination of the developing roller is evaluated based on the following criteria as to whether or not the toner is fused and contaminated on the photosensitive drum after printing 15,000 sheets in a high temperature and high humidity environment (30 ° C./80% RH). It was judged.
A: No toner fusion is observed on the photosensitive drum.
◯: Visual adhesion of the photosensitive drum is not visually recognized, but the fusion can be confirmed by enlarging with a microscope. However, there is no practical problem.
X: The fusion of toner is visually recognized on the photosensitive drum, and the actual image is adversely affected.

(Evaluation of horizontal streaks by blade contact marks)
The horizontal streak evaluation based on the blade contact mark of the developing roller is as follows. The electrophotographic process cartridge having the developing roller is left in a high-temperature and high-humidity environment (40 ° C./95% RH) for one week, and then normal temperature and normal humidity (23 ° C., 55 % RH) A solid image was output in an environment, and whether or not horizontal streaks due to blade contact traces were observed was determined according to the following criteria.
○: No horizontal stripes are observed Δ: Horizontal stripes are slightly observed, but there is no practical problem.

  The evaluation results for each roller are summarized in Table 1. As is apparent from the results of Examples 1 to 5 shown in Table 1, a developing roller having a shaft core body, a conductive elastic layer provided on the shaft core body, and a conductive resin layer constituting the outermost layer. The developing roller in which the microfriction μ of the surface in the developing region of the developing roller is 300 ≦ μ ≦ 2000 is clearly a high-performance developing roller in which drum contamination with toner does not occur effectively. became. In Comparative Examples 1 and 2, the photosensitive drum is contaminated because it does not conform to the microfriction range of the present invention. In addition, since the molecular weight of the polyurethane polyol prepolymer is not in the preferred range, horizontal streaks due to blade contact traces are generated.

FIG. 2 is a schematic cross-sectional view showing the structure of the developing roller of the present invention, the left figure is a schematic cross-sectional view cut in a direction perpendicular to the axial direction, and the right figure is a schematic cross-sectional view cut in a direction parallel to the axial direction. is there. 1 is a conceptual diagram showing a configuration of an electrophotographic image forming apparatus using a developing roller of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft core body 2 Conductive elastic layer 3 Conductive resin layer 4 Developing roller 5 Photosensitive drum 6 Toner application roller 7 Developing blade 8 Charging roller 9 Cleaning blade 10 Transfer roller 11 Fixing roller

Claims (8)

A mandrel, and provided on the the mandrel conductive elastic layer, and have a conductive resin layer constituting the outermost layer,
The conductive resin layer contains a linear polyurethane polyol prepolymer obtained by extending the chain of the bifunctional polyol (a) and the bifunctional isocyanate compound (b) in the range of 70 to 95% by mass and the isocyanate compound. A developing roller containing a urethane resin obtained by curing a urethane resin raw material mixture,
A developing roller having a microfriction degree μ of 300 ≦ μ ≦ 2000 in a developing region on the surface of the developing roller. The developing roller according to 請 Motomeko 1 micro friction of mu is Ru 500 ≦ μ ≦ 1200 der in the developing region before Symbol developing roller surface. The linear polyurethane polyol prepolymer, Weight average molecular weight of 10,000 to 50,000, and a molecular weight dispersity is under Mz / Mw = 2.5 or less,
Or One, developing roller according to 請 Motomeko 1 or 2 MD1 hardness Ru 25 to 50 ° der of the conductive resin layer. The developing roller according to any one of the bifunctional polyol (a) is Ru Oh polyether polyol 請 Motomeko 1-3. The developing roller according to the After completing the curing reaction of the conductive resin layer, further either Der Ru請 Motomeko 1-4 which was heat treated.   An electrophotographic process cartridge comprising the developing roller according to claim 1.   In an electronic image forming apparatus having a developing roller for carrying a toner on a surface to form a toner thin film, and contacting the latent image carrier in this state and supplying the toner to the latent image carrier An electrophotographic image forming apparatus, wherein the developing roller is the developing roller according to claim 1. A shaft core body, a conductive elastic layer provided on the shaft core body, and a conductive resin layer constituting the outermost layer, and a microfriction μ of the surface in the development region of the outermost layer is 300 or more A developing roller manufacturing method of 2000 or less,
(I) A linear polyurethane obtained by extending a chain of a bifunctional polyol (a) and a bifunctional isocyanate compound (b), having a weight average molecular weight of 10,000 to 50,000 and a molecular weight dispersity of Mz / Mw = 2.5 or less. A step of curing a urethane resin raw material mixture containing 70 to 95% by mass of a polyol prepolymer, an isocyanate compound, and a conductive material on the peripheral surface of the conductive elastic layer to obtain a urethane resin layer;
(Ii) heat-treating the urethane resin layer at a temperature of 130 ° C. or higher and 180 ° C. or lower for 1 hour to 24 hours;
A method for producing a developing roller, comprising:

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