JP4912383B2 - Developing roller, electrophotographic process cartridge, electrophotographic image forming apparatus - Google Patents

Description

  The present invention relates to a developing roller, an electrophotographic process cartridge using the developing roller, and an electrophotographic image forming apparatus.

  As an image forming method of an electrophotographic image forming apparatus such as a copying machine or an optical printer, a developing method using a non-magnetic one-component toner is known. Specifically, a photosensitive member which is a rotatable latent image carrier is charged by a charging unit such as a charging roller, and a laser beam is exposed on the surface of the charged photosensitive member to form an electrostatic latent image. Next, in the developing device of the image forming apparatus, the toner in the developer container is applied onto the developing roller by the developer supply roller and the developer amount regulating member, and electrostatic charging by the toner is performed at the contact portion between the photosensitive member and the developing roller. The latent image is developed. Thereafter, the toner image on the photosensitive member is transferred onto the recording material via the intermediate transfer member at or without the transfer portion at the transfer portion, and the toner image is fixed on the recording material by heat and pressure at the fixing portion, and the fixed image is formed. The recording material is discharged out of the image forming apparatus.

  In such an image forming method, examples of the developing device include those having the following configurations. A developing roller is provided so that the opening of the developer container for storing the toner is closed and a part of the developer container is exposed to the outside of the container, and the exposed part faces the photoreceptor. In the developer container, there are provided a developer supply roller for supplying toner to the developing roller, and a developer amount regulating member for forming the toner on the developing roller in a thin layer and making the toner on the developing roller a constant amount. It is done. After the development of the electrostatic latent image, the toner remaining on the developing roller is scraped off by the developer supply roller and mixed with the toner in the developer container.

  In such a non-magnetic one-component developing method, in order to stabilize the image density from the initial stage of image formation, a metal developer regulating member is used, and a voltage difference is provided between the developing roller and the toner on the developing roller is appropriate. Giving a triboelectric charge. The developing roller is required to have a predetermined electric resistance value and to apply appropriate triboelectric charge to the toner in combination with the developer regulating member.

  As a method of increasing the triboelectric charge amount of the toner on the developing roller in response to the above requirement, a method of adding magnesium stearate to the developing roller is known (Patent Document 1).

  However, in recent years, as a result of speeding up of the electrophotographic apparatus, the shearing force applied to the toner is increased more than before, and there is a tendency that the toner is deformed and the toner is deteriorated such that the external additive of the toner is dropped. In addition, when used continuously for a long period of time, the additive in the developing roller may bleed out, and the charging performance of the developing roller may not be maintained. As a result, there is a problem that the frictional charging of the toner after continuous image output and the fogging associated therewith occur.

  Further, when a potential difference is provided between the developer regulating member and the developing roller, an electric field is continuously applied to the developing roller, so that the developing roller after continuous image output is easily charged up. As a result, the difference between the potential of the developing roller and the potential of the photosensitive drum is reduced, and fog is likely to occur due to the toner having a small frictional charge amount.

Further, if resistance unevenness exists in the developing roller, the high resistance region of the developing roller tends to be charged up more. As for the surface potential of the developing roller corresponding to the high resistance region, the charge-up amount is added to the preset developing bias, and the image density becomes high. For this reason, image density unevenness corresponding to resistance unevenness of the developing roller may occur after continuous image output.
JP-A-9-96960

  An object of the present invention is to provide a developing roller, an electrophotographic process cartridge, and an electrophotographic image forming apparatus capable of suppressing fogging after continuous image output and suppressing unevenness of image density.

  The inventors of the present invention are able to suppress fogging and uneven image density after continuous image output by including a metal salt of a fatty acid having specific properties in the resin composition constituting the elastic layer of the developing roller. I found it. Based on this knowledge, the present invention has been completed.

That is, the present invention is a developing roller having a conductive shaft and an elastic layer formed on the outer peripheral surface of the conductive shaft,
The elastic layer is composed of a resin composition containing a resin and a metal salt of a fatty acid,
The content of the metal salt in the resin composition is 0.1 to 20 parts by mass with respect to 100 parts by mass of the resin, and
The developing roller is characterized in that the metal salt satisfies the following conditions (A) to (C):
(A) the fatty acid has one hydroxyl group,
(B) the fatty acid has 12 to 18 carbon atoms,
(C) a metal fatty acid metal salt is zinc.

  According to another aspect of the present invention, there is provided an electrophotographic process cartridge that is detachable from an electrophotographic image forming apparatus having a developing roller that supplies toner to the surface of the latent image carrier to form a toner image. The present invention relates to an electrophotographic process cartridge.

  According to another aspect of the present invention, there is provided an electrophotographic image forming apparatus provided with a developing roller that supplies toner to the surface of the latent image carrier to form a toner image. The present invention relates to a forming apparatus.

  Even when the developing roller of the present invention is applied to a high-speed and high-durability electrophotographic apparatus, it can impart a stable and appropriate triboelectric charge to the toner, and further prevent the developing roller surface from being charged up. Therefore, it is possible to suppress fogging and image density unevenness after continuous image output. The electrophotographic process cartridge and the electrophotographic image forming apparatus of the present invention can perform stable image formation.

(Development roller)
The developing roller of the present invention has a configuration as shown in FIG. 1 as an example. The developing roller 1 according to the present invention shown in FIG. 1 includes a conductive shaft body 2 and an elastic layer 4 provided on the outer peripheral surface of the conductive shaft body 2.

(Conductive shaft)
The conductive shaft body 2 used in the developing roller 1 of the present invention has a strength capable of supporting the elastic layer 4 formed on the outer periphery, and has conductivity that functions as an electrode of the elastic layer 4. Examples of the material of the conductive shaft 2 include metals or alloys such as aluminum, copper alloys and stainless steel; iron plated with chromium or nickel; and synthetic resins having conductivity. Furthermore, the metal shaft body may be subjected to rust prevention treatment such as plating and oxidation treatment.

  The shape of the conductive shaft body 2 may be either a columnar shape or a cylindrical shape, and the surface may be primed as necessary. Examples of the outer diameter of the conductive shaft include a range of 4 mm to 10 mm in diameter.

(Elastic layer)
The elastic layer 4 formed on the outer peripheral surface of the conductive shaft 2 is composed of a resin composition containing a metal salt of a fatty acid, and the content of the metal salt of the fatty acid in the elastic layer is a resin 100. It is 0.1-20 mass parts with respect to a mass part. The fatty acid metal salt satisfies the following conditions (A) to (C):
(A) the fatty acid has one hydroxyl group,
(B) the fatty acid has 12 to 18 carbon atoms,
(C) The metal of the fatty acid metal salt is zinc, calcium, or magnesium.

  By forming the elastic layer 4 with such a resin composition containing a fatty acid metal salt, fogging and unevenness in image density after continuous image output can be suppressed.

  Here, in the metal salt of a fatty acid used in the present invention, the fatty acid has one hydroxyl group (per one fatty acid molecule). When the fatty acid has one hydroxyl group, it contributes to suppression of the charge-up of the developing roller, and image density unevenness can be prevented. Although the detailed mechanism of charge-up suppression by having a hydroxyl group is not clear, it is assumed that the hydroxyl group functions slightly ionically. Further, since the fatty acid has a hydroxyl group, the toner charging performance can be maintained even after continuous image output, and fogging can be suppressed. This is presumably because having a hydroxyl group increases the affinity between the fatty acid metal salt and the resin component of the elastic layer, so that the toner charging performance can be maintained without bleeding out after continuous image output. . Although the fatty acid metal salt having no hydroxyl group has charging performance with respect to the initial toner, the developing roller is easily charged up, and image density unevenness occurs. Further, since the affinity with the resin is inferior, if the continuous image output is advanced, the charging performance with respect to the toner is decreased and the fogging is increased. Further, when the fatty acid of the fatty acid metal salt has two or more hydroxyl groups (per one fatty acid molecule), the effect of suppressing the charge-up of the developing roller is enhanced, but the charging performance for the toner is reduced and the effect of suppressing fogging is insufficient. become.

  In the fatty acid metal salt, the fatty acid has 12 to 18 carbon atoms. From the study by the present inventors, it was found that the charging performance for the toner increases as the number of carbon atoms of the fatty acid increases. From the above examination results, when the carbon number is 11 or less, the charging performance with respect to the toner is reduced and the fogging is increased. Moreover, regarding the metal salt of a fatty acid having 19 or more carbon atoms having one hydroxyl group, the effect has not been confirmed because the raw materials could not be obtained. However, as the number of carbon atoms is increased, the toner charging performance is improved, but the effect of suppressing charge-up tends to be diminished, and it is presumed that the unevenness of image density increases.

  In other words, in the present invention, in order to achieve a balance between improving charging performance and suppressing charge-up of the developing roller, it is considered that the balance between the number of carbon atoms of the fatty acid and the number of hydroxy groups is important in the metal salt of the fatty acid. It is done.

  Examples of the fatty acid having 12 to 18 carbon atoms having one hydroxyl group include 12-hydroxystearic acid, 16-hydroxypalmitic acid, 15-hydroxypentadecanoic acid, and 12-hydroxylauric acid. Among these, 12-hydroxystearic acid is preferable because it has a good balance between fog suppression effect after continuous image output and image density unevenness.

  Further, in the metal salt of fatty acid, the metal is zinc, calcium, or magnesium, and zinc that has a good balance between the fog suppression effect after continuous image output and the image density unevenness is preferable. Although the detailed mechanism of obtaining good results by using zinc is not clear, it is considered that moderate electronegativity contributes to the suppression of the charging performance of the toner and the charge-up of the developing roller. Note that alkali metal salts of fatty acids are not preferable because they are highly soluble in water, bleed out during continuous image output, and fog increases after continuous image output.

  Moreover, content of the metal salt of the fatty acid in the resin composition which comprises the elastic layer 4 of this invention is 0.1 thru | or 20 mass parts with respect to 100 mass parts of resin. When the content is less than 0.1 parts by mass, the triboelectric chargeability with respect to the toner becomes small, and the fog suppression effect becomes small. On the other hand, when the amount is more than 20 parts by mass, the charge-up of the developing roller increases, and the image density unevenness increases. Preferably, it is 1 to 10 parts by mass. The content of the fatty acid metal salt in the resin composition constituting the elastic layer 4 can be determined by extracting the fatty acid metal salt from the elastic layer 4 using heated toluene. The metal of the fatty acid metal salt can be identified by measuring the extracted fatty acid metal salt using a fluorescent X-ray analyzer. Moreover, the number of hydroxyl groups and the number of carbon atoms can be determined by suspending a metal salt of a fatty acid in dilute hydrochloric acid to liberate the fatty acid and measuring it using NMR or HPLC.

  Specific examples of the resin material of the resin composition constituting the elastic layer 4 include polyamide, polyurethane resin, urea resin, polyimide, melamine resin, fluororesin, phenol resin, alkyd resin, silicone resin, and polyester. Can be mentioned. These resins can be used alone or in combination of two or more as required. Among these, a polyurethane resin is preferable because it is excellent in charging performance of the toner, has abrasion resistance, has high polarity, and can well hold the metal salt of the fatty acid of the present invention. The resin material of the resin composition can be identified by measuring the elastic layer using a Fourier transform infrared visible spectrophotometer.

  Examples of the polyurethane resin include ether polyurethane resins, ester polyurethane resins, acrylic polyurethane resins, and carbonate polyurethane resins. Among these, a polyether polyurethane resin that easily imparts a negative charge to the toner by friction with the toner is preferable.

  The polyether polyurethane resin can be obtained by a reaction between a known polyether polyol and an isocyanate compound. Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Further, these polyol components may be prepolymers that are chain-extended with isocyanate in advance as required. Examples of the isocyanate are listed below. 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI) and the like.

  Although it does not specifically limit as an isocyanate compound made to react with these polyol components, The following can be used. 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 polyisocyanates such as tolylene diisocyanate, 2,6-tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), modified products and copolymers thereof, block bodies thereof, and the like.

  If the developing roller 1 requires surface roughness, fine particles for controlling the roughness may be added to the elastic layer 4. The volume average particle diameter of the fine particles for roughness control is preferably 3 to 20 μm. The amount of the fine particles added to the elastic layer 4 is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the resin of the elastic layer 4.

  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.

  The elastic layer 4 preferably contains a conductive agent. As the conductive agent, carbon black is preferable because the charging performance with respect to the toner and the charge-up suppression of the developing roller 1 can be controlled in an optimal balance.

Specific examples of the carbon black include the following.
"Ketjen Black" (trade name, manufactured by Lion Corporation), conductive carbon black such as acetylene black; carbon black for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, MT, etc. In addition, carbon black for color ink and pyrolytic carbon black that have been subjected to oxidation treatment can be used.

  The amount of carbon black added is preferably 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin. The content of carbon black can be determined by measuring the elastic layer using a thermogravimetric analyzer (TGA).

  In addition to the above carbon black, usable conductive agents include the following. Graphite such as natural graphite and artificial graphite; metal powder such as copper, nickel, iron and aluminum; metal oxide powder such as titanium oxide, zinc oxide and tin oxide; conductive polymer such as polyaniline, polypyrrole and polyacetylene. These may be used alone or in combination of two or more as required.

  In addition, the elastic layer 4 has a crosslinking agent, a plasticizer, a filler, an extender, a vulcanizing agent, a vulcanization aid, a crosslinking aid, an antioxidant, as long as the functions of the resin and the conductive agent are not impaired. An anti-aging agent and a processing aid can be contained.

  Examples of the thickness of the elastic layer 4 include a range of 1 μm to 5 mm. The thickness of the elastic layer 4 can be obtained by observing and measuring the cross section with an optical microscope.

(Base layer)
As illustrated in FIG. 2, the developing roller of the present invention may have a base layer 3 between the conductive shaft body 2 and the elastic layer 4. The base layer 3 has a hardness and elasticity that can be pressed against the photosensitive member with an appropriate nip width and nip pressure so that the toner can be supplied to the electrostatic latent image formed on the surface of the photosensitive member without excess or deficiency. It is provided to give to. The base layer 3 is preferably formed of a rubber material, and specific examples 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, NBR hydride, urethane rubber. These can be used alone or in combination of two or more. Of these, it is particularly preferable to use silicone rubber. Examples of the silicone rubber include polydimethylsiloxane, polymethyltrifluoropropylsiloxane, polymethylvinylsiloxane, polyphenylvinylsiloxane, and copolymers of these polysiloxanes.

  The base layer 3 is preferably made semiconductive by containing a conductive agent. As the conductive agent, either an ionic conductive agent or an electronic conductive agent may be used. Specifically, carbon-based materials such as carbon black and graphite; metal powders such as copper, nickel, iron and aluminum; metal oxide powders such as titanium oxide, zinc oxide and tin oxide; conductive materials such as polyaniline, polypyrrole and polyacetylene. Can be mentioned. These can be used alone or in combination of two or more. These conductive agents can be used as powdered or fibrous fine particles. Among these, carbon black is preferable because it is effective in preventing charge-up of the developing roller 1 and is low in cost.

The volume resistivity of the base layer 3 is preferably in the range of 1 × 10 ³ Ω · cm to 1 × 10 ¹⁰ Ω · cm when a DC voltage of 100 V is applied. If the volume resistivity of the base layer 3 is within the above range, the toner can be triboelectrically charged and the charging of the developing roller 1 can be prevented. In the case of carbon black, the amount of the conductive agent used to make the base layer 3 have such a volume resistivity is preferably 15 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the rubber component. .

  Here, as the volume resistivity of the base layer 3, a value obtained by the following method can be adopted. An ultrahigh resistance meter “R8340A” (trade name, manufactured by Advantest) is used as the resistance meter, and measurement is performed under the following conditions.

Measurement mode: Program mode 5
(Charge and major 30 seconds, discharge 10 seconds)
Applied voltage: 100 (V)
Sample box: Sample box “TR42” (trade name, manufactured by Advantest) for measuring ultrahigh resistance meter, main electrode is 10 mm in diameter and 10 mm in thickness, guard ring electrode is 20 mm in inner diameter, 26 mm in outer diameter and 10 mm in thickness. To do.

  Test piece: First, a flat test piece in which the material of the base layer 3 is cured to the same thickness as the base layer 3 under the same conditions as those for forming the base layer 3 is prepared. Next, a test piece having a diameter of 30 mm is cut out from the test piece. On one side of the cut specimen, a vapor deposition film electrode (back electrode) is provided by performing Pt—Pd vapor deposition on the entire surface, and the 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 deposition film is obtained by using “mild sputter E1030” (trade name, manufactured by Hitachi, Ltd.) and performing a vapor deposition operation at a current value of 15 mA for 2 minutes. 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 (cm) × 0.75 (cm) × RM (Ω) ÷ (4 × t (cm))
In the base layer 3, other than the above, the crosslinking agent, plasticizer, filler, extender, vulcanizing agent, vulcanizing aid, crosslinking aid, antioxidant, Various additives such as anti-aging agent and processing aid can be contained. Among the fillers, examples of the nonconductive filler include silica, quartz powder, titanium oxide, zinc oxide, and calcium carbonate. Examples of the crosslinking agent include di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and dicumyl peroxide.

  The thickness of the base layer 3 can be appropriately selected so as to have a desired elasticity in relation to the developer regulating member and the photoconductor, and can include, for example, a range of 2.0 mm to 6.0 mm. More preferably, the thickness is 3.0 to 5.0 mm.

(Development roller manufacturing method)
Examples of the method for producing the developing roller of the present invention include a method of forming the elastic layer 4 on the conductive shaft body 2 or on the base layer 3 formed on the conductive shaft body 2 by a method described later.

  For forming the elastic layer 4, a resin composition is prepared by mixing the resin, a metal salt of the fatty acid, a conductive agent such as carbon black, a solvent, and other additives as required. This can be used for molding and curing using extrusion molding, molding or injection molding, but the coating molding method is preferred. As the coating molding method, spraying, dipping, roll coating or the like can be used. After forming a coating film on the conductive shaft 2 or the base layer 3, this is dried to remove the solvent. Heat curing methods can be used. Specifically, curing may be performed by either heating or electron beam irradiation. In the case of heating, for example, the temperature can be 120 to 180 ° C. and the curing time can be 60 to 300 minutes.

  When the dip coating molding method is used for forming the elastic layer 4, a coating apparatus as shown in FIG. 3 can be used as an example.

  In FIG. 3, the coating apparatus has a cylindrical shape having an inner diameter slightly larger than the outer diameter of the conductive shaft body 2 or the base layer 3 and a depth capable of immersing the conductive shaft body 2 or the base layer 3 in the axial direction. Immersion tank 26 is provided. An annular liquid receiving portion is provided on the outer periphery of the upper edge of the immersion tank 26 and is connected to the stirring tank 28. The bottom of the immersion tank 26 is connected to a stirring tank 28.

  The paint in the stirring tank 28 is fed into the bottom of the immersion tank 26 by the liquid feed pump 27. From the upper end of the immersion tank, the paint overflows and returns to the agitation tank 28 via the liquid receiving part on the outer periphery of the upper edge of the immersion tank 26. The conductive shaft body 2 or the base layer 3 is fixed vertically to the lifting device 29, immersed in the immersion tank 26, and pulled up to form a coating film.

  After the coating film is formed, the resin composition coating film is dried and then heat-cured to produce the elastic layer 4. Heat curing is performed for 60 to 300 minutes in an environment at a temperature of 120 to 180 ° C.

(Image forming apparatus for electrophotography)
An example of the electrophotographic image forming apparatus of the present invention is shown in FIG. In FIG. 4, image forming units a to d are provided for each color toner of yellow toner, magenta toner, cyan toner, and black toner. Each of the image forming units a to d is provided with a photoreceptor 5 as an electrostatic latent image carrier that rotates in the direction of the arrow. Around each photoconductor 5, a charging device 11 for uniformly charging the photoconductor 5, and exposure means for forming an electrostatic latent image by irradiating the uniformly charged photoconductor 5 with a laser beam 10 A developing device 9 is provided that supplies toner to the photosensitive member 5 on which the electrostatic latent image is formed to develop the electrostatic latent image.

  On the other hand, a transfer conveyance belt 20 that conveys a recording material 22 such as paper supplied by a paper supply roller 23 is provided suspended from a driving roller 16, a driven roller 21, and a tension roller 19. The transfer / conveying belt 20 is charged with the charge of the attracting bias power supply 25 via the attracting roller 24, and the recording material 22 is electrostatically attached to the surface to be transported.

  A transfer bias power source 18 is provided for applying a charge for transferring the toner images on the photoreceptor 5 of the image forming units a to d to the recording material 22 conveyed by the transfer conveyance belt 20. The transfer bias is applied via a transfer roller 17 disposed on the back surface of the transfer conveyance belt 20. The toner images of the respective colors formed in the image forming units a to d are sequentially superimposed and transferred onto a recording material 22 conveyed by a transfer conveyance belt 20 that is moved in synchronization with the image forming units a to d. It has come to be.

  Further, the electrophotographic image forming apparatus includes a fixing device 16 that fixes the toner image superimposed and transferred on the recording material 22 by heating, and a conveyance device (not shown) that discharges the image-formed recording material 22 to the outside. Is provided.

  On the other hand, each of the image forming units a to d is provided with a cleaning device 12 having a cleaning blade that removes transfer residual toner that is not transferred onto each photoreceptor 5 and cleans the surface. Further, a waste toner container for storing toner scraped off from the photoreceptor 5 is provided. The cleaned photoconductor 5 is set in an image-formable state and is in a standby state.

  A developing device 9 provided in each of the image forming units a to d is provided with a developer container 7 containing a non-magnetic developer as a one-component developer, and an opening of the developer container 7 so as to close the developer container 7. A developing roller 1 is provided so as to face the photoconductor at a portion exposed from the agent container.

In the developer container 7, a developer supply roller 6 and a developer amount regulating member 8 are provided.
The developer supply roller 6 supplies toner to the developing roller 1 and scrapes off toner remaining on the developing roller 1 after development without being used. The developer amount regulating member 8 forms the toner on the developing roller 1 in a thin film shape and is frictionally charged. These are arranged in contact with the developing roller 1, respectively. A developer amount regulating member bias power source 13 is connected to the developer amount regulating member 8, and a developing roller bias power source 14 is connected to the developing roller 1, and the developer amount regulating member 8 and the developing roller 1 are connected during image formation. Each is charged with a charge. The voltage output from the developer amount regulating member bias power supply 13 is 50 V to 400 V lower than the voltage output from the developing roller bias power supply 14 (electrophotographic process cartridge).
An example of the electrophotographic process cartridge of the present invention is shown in FIG. The electrophotographic process cartridge shown in FIG. 5 has a developing device 9, a photoreceptor 5, and a cleaning device 12, and these are integrated and detachably provided on the main body of the electrophotographic image forming apparatus. Examples of the developing device 9 include the same ones as described in the electrophotographic image forming apparatus. In addition to the above, the electrophotographic process cartridge of the present invention may be one in which a transfer member for transferring the toner image on the photosensitive member 5 to the recording material 22 is provided integrally with the above members.

  Hereinafter, the developing roller, the electrophotographic process cartridge, and the electrophotographic image forming apparatus of the present invention will be described in detail, but the technical scope of the present invention is not limited thereto.

<Preparation of fatty acid metal salt>
(Fatty acid metal salt preparation example 1)
A 5 L reaction layer was charged with 480 g of 12-hydroxystearic acid, 135 g of 48% sodium hydroxide aqueous solution and about 3600 g of water, and heated at 90 ° C. for 30 minutes to prepare a 12-hydroxy sodium stearate aqueous solution. .

Next, 645 g of 20 mass% ZnSO ₄ aqueous solution was added to the aqueous solution kept at 90 ° C. over 30 minutes, and then kept at 90 ° C. for 30 minutes to obtain a slurry of zinc 12-hydroxystearate. .

  The slurry was dehydrated with a filter press to obtain a cake of zinc 12-hydroxystearate, and the cake was washed with hot water at 60 ° C. Further, the cake was dried in a hot air dryer at 105 ° C. and then pulverized to obtain a powder of zinc 12-hydroxystearate.

(Fatty acid metal salt preparation example 2)
445 g of 20% strength by weight CaCl ₂ aqueous solution was added to 90 ° C. aqueous 12-hydroxystearate solution prepared in the same manner as in Preparation Example 1 over 30 minutes, and then maintained at 90 ° C. for 30 minutes. A slurry of calcium hydroxystearate was obtained. Thereafter, dehydration, washing, drying and pulverization were carried out in the same manner as in Preparation Example 1 to obtain a calcium 12-hydroxystearate powder.

(Fatty acid metal salt preparation example 3)
481 g of a 20 mass% MgSO ₄ aqueous solution was added over 30 minutes to a 90 ° C. aqueous 12-hydroxy sodium stearate solution prepared in the same manner as in Preparation Example 1. Thereafter, the slurry was kept in warm water at 90 ° C. for 30 minutes to obtain a slurry of 12-hydroxy magnesium stearate. Thereafter, dehydration, washing, drying and pulverization were carried out in the same manner as in Preparation Example 1 to obtain 12-hydroxy magnesium stearate powder.

(Fatty acid metal salt preparation example 4)
A 5 L reaction layer was charged with 505 g of 9,10-dihydroxystearic acid, 135 g of 48% sodium hydroxide aqueous solution and 3600 g of water, heated at 90 ° C. for 30 minutes, and sodium 9,10-dihydroxystearate aqueous solution. Was prepared.

Next, 645 g of a 20 mass% ZnSO ₄ aqueous solution was added to the aqueous solution kept at 90 ° C. over 30 minutes, and then kept at a temperature of 90 ° C. for 30 minutes to prepare a 9,10-dihydroxyzinc stearate slurry. Obtained. Thereafter, dehydration, washing, drying and pulverization were performed in the same manner as in Preparation Example 1 to obtain a 9,10-dihydroxystearic acid zinc powder.

(Fatty acid metal salt preparation example 5)
A 5 L reaction layer was charged with 435 g of 16-hydroxypalmitic acid, 135 g of 48% aqueous sodium hydroxide and 3600 g of water, and heated at a temperature of 90 ° C. for 30 minutes to prepare an aqueous 16-hydroxypalmitate solution.

Next, 645 g of a 20 mass% ZnSO ₄ aqueous solution was added to the above aqueous solution kept at 90 ° C. over 30 minutes, and then kept at a temperature of 90 ° C. for 30 minutes to obtain a slurry of zinc 16-hydroxypalmitate. . Thereafter, dehydration, washing, drying and pulverization were performed in the same manner as in Preparation Example 1 to obtain a powder of zinc 16-hydroxypalmitate.

(Fatty acid metal salt preparation example 6)
A 5 L reaction layer was charged with 413 g of 15-hydroxypentadecanoic acid, 135 g of 48% aqueous sodium hydroxide and 3600 g of water, and heated at a temperature of 90 ° C. for 30 minutes to prepare a 15-hydroxypentadecanoic acid aqueous solution.

Next, 645 g of a 20 mass% ZnSO ₄ aqueous solution was added to the aqueous solution kept at 90 ° C. over 30 minutes, and then kept at 90 ° C. for 30 minutes to obtain a slurry of zinc 15-hydroxypentadecanoate. . Thereafter, dehydration, washing, drying and pulverization were performed in the same manner as in Preparation Example 1 to obtain a zinc 15-hydroxypentadecanoate powder.

(Preparation Example 7 of fatty acid metal salt)
A 5 L reaction layer was charged with 413 g of 12-hydroxylauric acid, 135 g of 48% sodium hydroxide aqueous solution and 3600 g of water, and heated at a temperature of 90 ° C. for 30 minutes to prepare a sodium 12-hydroxylaurate aqueous solution.

Next, 645 g of a 20 mass% ZnSO ₄ aqueous solution was added to the above aqueous solution kept at 90 ° C. over 30 minutes, and then kept at a temperature of 90 ° C. for 30 minutes to obtain a slurry of zinc 12-hydroxylaurate. . Thereafter, dehydration, washing, drying and pulverization were carried out in the same manner as in Preparation Example 1 to obtain a zinc 12-hydroxylaurate powder.

(Fatty acid metal salt preparation example 8)
A 5 L reaction layer was charged with 304 g of 10-hydroxydecanoic acid, 135 g of 48% sodium hydroxide aqueous solution and 3600 g of water, and heated at a temperature of 90 ° C. for 30 minutes to prepare an aqueous 10-hydroxydecanoate aqueous solution.

Next, 645 g of a 20 mass% ZnSO ₄ aqueous solution was added to the above aqueous solution kept at 90 ° C. over 30 minutes, and then kept at a temperature of 90 ° C. for 30 minutes to obtain a slurry of zinc 10-hydroxydecanoate. . Thereafter, dehydration, washing, drying and pulverization were performed in the same manner as in Preparation Example 1 to obtain a zinc 10-hydroxydecanoate powder.

<Preparation of base layer>
A primer (trade name: “DY35-051”, manufactured by Toray Dow Corning Co., Ltd.) is applied to a conductive shaft made of SUS304 having an outer diameter of 8 mm and a length of 280 mm, and concentric in a cylindrical mold having an inner diameter of 16 mm. It installed so that it might become. An addition type silicone rubber composition in which the following materials were mixed was injected into the cylindrical mold.
Liquid silicone rubber material (trade name: “SE6724A / B”, manufactured by Toray Dow Corning Co., Ltd.): 100.0 parts by mass,
Carbon black (trade name: “Toka Black # 7360SB”, manufactured by Tokai Carbon Co., Ltd.): 35.0 parts by mass
Silica powder as heat resistance imparting agent: 0.2 parts by mass
Platinum catalyst: 0.1 part by mass

  After the mold was heated at a temperature of 130 ° C. for 20 minutes, the mold was cooled to 50 ° C., and the base layer integrated with the conductive shaft body was taken out of the mold. Next, the base layer integrated with the conductive shaft was heated at a temperature of 200 ° C. for 2 hours to complete the curing reaction, and a roller having a base layer with a thickness of 4 mm was produced.

[Example 1]
The following materials were mixed stepwise in methyl ethyl ketone (MEK) solvent.
Polytetramethylene glycol (trade name: “PolyTHF”, manufactured by BASF): 100 parts by mass, isocyanate (trade name: “Millionate MT” (MDI), manufactured by Nippon Polyurethane Industry Co., Ltd.): 14.0 parts by mass. It was made to react at 80 degreeC under nitrogen atmosphere for 3 hours, and the polyurethane polyol prepolymer was obtained.

  100 parts by mass of the polyurethane polyol prepolymer and 41.8 parts by mass of isocyanate (trade name: “Coronate 2521” (urethane-modified MDI), manufactured by Nippon Polyurethane Co., Ltd.) were added. At this time, the value of [NCO] / [OH] is 1.1. Further, zinc 12-hydroxystearate (prepared in Preparation Example 1 of fatty acid metal salt) is 5 parts by mass with respect to 100 parts by mass of the resin component, and carbon black (trade name: “MA100”, manufactured by Mitsubishi Chemical Corporation) is resin. 25 parts by mass was added to 100 parts by mass of the components. Then, 40 parts by mass of polyurethane resin particles (trade name: “ART PEARL C400” (φ14 μm), manufactured by Negami Kogyo Co., Ltd.) is added to the one added with MEK so that the total solid content is 30% by mass. What was stirred and dispersed was used as a raw material liquid for the elastic layer.

  The obtained elastic layer raw material solution is applied onto the previously molded base layer by dip coating so as to have a film thickness of 10.0 μm, dried in an oven at 80 ° C. for 15 minutes, and then in an oven at 140 ° C. for 2 hours. It hardened | cured and produced the developing roller.

<Image evaluation>
Laser beam printer “CLJ4700dn” manufactured by Japan Hewlett-Packard Co. having the configuration of the electrophotographic image forming apparatus shown in FIG. 4 (trade name, printing speed was changed from 30 sheets / minute to 40 sheets / minute. ) And a CLJ4700dn print cartridge having the configuration of the electrophotographic process cartridge shown in FIG. 5 (the developer amount regulating member is changed to 80 μm thick made of SUS304, hereinafter referred to as a modified cartridge). The image evaluation (fogging evaluation, image density unevenness evaluation) was performed as follows.

(Cover evaluation)
After the developing roller was loaded into the modified cartridge, it was left for 24 hours in a high temperature and high humidity environment at a temperature of 35 ° C. and a humidity of 85% RH. After that, under the same environment, the modified cartridge is loaded into the modified machine, bias -300V is applied to the developing roller, bias -500V is applied to the developer regulating member made of SUS304, and a white solid image is output at a speed of 10 sheets / minute. Stopped. The toner adhering to the photoreceptor was peeled off with a transparent tape (trade name: “Polyester Tape No. 550”, manufactured by Nichiban Co., Ltd.). Next, this tape is affixed to white paper (trade name: “Business Multipurpose 4200”, manufactured by XEROX) and applied to a reflection densitometer (trade name: “TC-6DS / A”, manufactured by Tokyo Denshoku). The reflection density was measured. At that time, a green filter was used as a filter. Only the transparent tape was attached to white paper as a reference, the amount of decrease in reflectance (%) relative to the reference was defined as a fog value (%), and initial fog evaluation was performed according to the following criteria.

  Furthermore, after continuously outputting 30,000 sheets of LETTER size paper at a printing rate of 1% at a speed of 40 sheets / minute, the printer is stopped while outputting a white solid image at a speed of 10 sheets / minute, and continuously in the same manner as described above. After image output, fogging evaluation was performed. The evaluation criteria for fogging are as follows. The results are shown in Table 1.

A: Less than 2.5% B: 2.5% or more and less than 5% C: 5% or more.

(Image density unevenness evaluation)
After the developing roller was loaded into the modified cartridge, it was left for 24 hours in a low temperature and low humidity environment at a temperature of 10 ° C. and a humidity of 7% RH. After that, in the same environment, the modified cartridge is loaded into the modified machine, bias-300 V is applied to the developing roller, bias-500 V is applied to the developer regulating member, and LETTER size paper is printed at a rate of 1% at a speed of 40 sheets / minute Was continuously output. Thereafter, a bias of −300 V was applied to the developing roller and a bias of −600 V was applied to the developer amount regulating member, a halftone image was output, and evaluation was performed according to the following criteria.

A: Density unevenness is not recognized on the image B: Light unevenness is slightly recognized on the image C: Light unevenness is remarkably recognized on the image.

  In addition, as a comprehensive judgment, A and the case where the fog and the image shading unevenness are compatible at a high level, B that the fog and the image shading unevenness are compatible, and either the fog and the image shading unevenness are slightly inferior, but there is no practical problem. The thing was set to C. Table 1 shows the type, content, and image evaluation results of the fatty acid metal salt.

[ Reference Example 1 ]
A developing roller was prepared in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to calcium 12-hydroxystearate (prepared in Preparation Example 2 of fatty acid metal salt), and image evaluation was performed. Table 1 shows the type, content, and image evaluation results of the fatty acid metal salt.

[ Reference Example 2 ]
A developing roller was produced in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to magnesium 12-hydroxystearate (prepared in Preparation Example 3 of fatty acid metal salt), and image evaluation was performed. Table 1 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Comparative Example 1]
A developing roller was prepared in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to zinc stearate (trade name: “SZ-2000”, manufactured by Sakai Chemical Industry Co., Ltd.), and image evaluation was performed. It was. Table 1 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Comparative Example 2]
A developing roller was prepared in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to magnesium stearate (trade name: “SM-1000”, manufactured by Sakai Chemical Industry Co., Ltd.), and image evaluation was performed. It was. Table 1 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Comparative Example 3]
A developing roller was prepared and image evaluation was performed in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to calcium stearate (trade name: “SC-100”, manufactured by Sakai Chemical Industry Co., Ltd.). . Table 1 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Comparative Example 4]
A developing roller was produced in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to lithium 12-hydroxystearate (trade name: “S-7000H”, manufactured by Sakai Chemical Industry Co., Ltd.). Evaluation was performed. Table 1 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Comparative Example 5]
A developing roller was prepared in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to zinc 9,10-dihydroxystearate (prepared in Preparation Example 4 of fatty acid metal salt), and image evaluation was performed. Table 1 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Comparative Example 6]
A developing roller was prepared in the same manner as in Example 1 except that 12-hydroxyzinc stearate was not added, and image evaluation was performed. Table 1 shows the type, content, and image evaluation results of the fatty acid metal salt.

  From the above results, the fatty acid of the fatty acid metal salt has one hydroxyl group, and the metal of the fatty acid metal salt is any one of zinc, calcium, and magnesium, thereby suppressing fogging and image density after continuous image output. It can be seen that the suppression of unevenness can be achieved at the same time.

[Example 2 ]
A developing roller was produced in the same manner as in Example 1 except that the amount of zinc 12-hydroxystearate was changed to 0.1 parts by mass with respect to 100 parts by mass of the resin component, and image evaluation was performed. Table 2 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Example 3 ]
A developing roller was produced in the same manner as in Example 1 except that the amount of zinc 12-hydroxystearate was changed to 1 part by mass with respect to 100 parts by mass of the resin component, and image evaluation was performed. Table 2 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Example 4 ]
A developing roller was prepared in the same manner as in Example 1 except that the amount of zinc 12-hydroxystearate was changed to 10 parts by mass with respect to 100 parts by mass of the resin component, and image evaluation was performed. Table 2 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Example 5 ]
A developing roller was produced in the same manner as in Example 1 except that the amount of zinc 12-hydroxystearate was changed to 20 parts by mass with respect to 100 parts by mass of the resin component, and image evaluation was performed. Table 2 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Comparative Example 7]
A developing roller was produced in the same manner as in Example 1 except that the amount of zinc 12-hydroxystearate was changed to 0.05 parts by mass with respect to 100 parts by mass of the resin component, and image evaluation was performed. Table 2 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Comparative Example 8]
A developing roller was produced in the same manner as in Example 1 except that the amount of zinc 12-hydroxystearate was changed to 30 parts by mass with respect to 100 parts by mass of the resin component, and image evaluation was performed. Table 2 shows the type, content, and image evaluation results of the fatty acid metal salt.

  From the above results, by setting the addition amount of the fatty acid metal salt within the range of the present invention, it is possible to achieve both suppression of fogging after continuous image output and suppression of unevenness of image density.

[Example 6 ]
A developing roller was prepared in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to zinc 16-hydroxypalmitate (prepared in Preparation Example 5 of fatty acid metal salt), and image evaluation was performed. Table 3 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Example 7 ]
A developing roller was produced in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to zinc 15-hydroxypentadecanoate (prepared in Preparation Example 6 of fatty acid metal salt), and image evaluation was performed. Table 3 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Example 8 ]
A developing roller was prepared in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to zinc 12-hydroxylaurate (prepared in Preparation Example 7 of fatty acid metal salt), and image evaluation was performed. Table 3 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Comparative Example 9]
A developing roller was prepared in the same manner as in Example 1 except that 12-hydroxyzinc stearate was changed to zinc 10-hydroxydecanoate (prepared in Preparation Example 8 of fatty acid metal salt). Image evaluation Image evaluation was performed. The results are shown in Table 3.

[Comparative Example 10]
A developing roller was produced in the same manner as in Example 1 except that zinc 12-hydroxystearate was changed to zinc laurate (trade name: “Z-12”, manufactured by Sakai Chemical Industry Co., Ltd.), and image evaluation was performed. It was. Table 3 shows the type, content, and image evaluation results of the fatty acid metal salt.

  From the above results, by setting the carbon number of the fatty acid metal salt within the range of the present invention, it is possible to achieve both suppression of fogging after continuous image output and suppression of unevenness of image density. Further, when Comparative Example 1 and Comparative Example 10 are compared, it can be seen that image density unevenness increases as the number of carbon atoms increases.

[Example 9 ]
Example 1 except that the amount of zinc 12-hydroxystearate was changed to 2.5 parts by mass, and further 2.5 parts by mass of calcium 12-hydroxystearate (prepared in Preparation Example 2 of fatty acid metal salt) was added. Similarly, a developing roller was prepared and image evaluation was performed. Table 4 shows the type, content, and image evaluation results of the fatty acid metal salt.

[Example 10 ]
Example 1 except that the amount of zinc 12-hydroxystearate was changed to 2.5 parts by mass and 2.5 parts by mass of zinc 12-hydroxylaurate (prepared in Preparation Example 7 of fatty acid metal salt) was further added. A developing roller was prepared in the same manner as described above, and image evaluation was performed. Table 4 shows the type, content, and image evaluation results of the fatty acid metal salt.

  From the above results, it was found that good results were obtained even when two types of fatty acid metal salts in the present invention were mixed.

  From the above results, by using the developing roller of the present invention, it is possible to achieve both suppression of fog after continuous image output and suppression of unevenness of image density.

It is a schematic side view which shows an example of the developing roller of this invention. It is a schematic side view which shows an example of the developing roller of this invention. It is a schematic block diagram which shows an example of the manufacturing apparatus 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. 1 is a schematic configuration diagram showing an example of an electrophotographic process cartridge of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing roller 2 Conductive shaft 3 Base layer 4 Elastic layer 5 Photoconductor 6 Developer supply roller 7 Developer container 8 Developer amount regulating member 9 Developing device 10 Laser beam 11 Charging device 12 Cleaning device 13 Developer amount regulating member bias Power supply 14 Developing roller bias power supply 15 Fixing device 16 Driving roller 17 Transfer roller 18 Transfer bias power supply 19 Tension roller 20 Transfer conveying belt 21 Driven roller 22 Recording material 23 Paper feed roller 24 Adsorption roller 25 Adsorption bias power supply 26 Immersion tank 27 Liquid feed pump 28 Stirring tank 29 Lifting device

Claims (4)

A developing roller having a conductive shaft and an elastic layer formed on the outer peripheral surface of the conductive shaft,
The elastic layer is composed of a resin composition containing a resin and a metal salt of a fatty acid,
The content of the metal salt in the resin composition is 0.1 to 20 parts by mass with respect to 100 parts by mass of the resin, and
The developing roller, wherein the metal salt satisfies the following conditions (A) to (C):
(A) the fatty acid has one hydroxyl group,
(B) the fatty acid has 12 to 18 carbon atoms,
(C) a metal fatty acid metal salt is zinc.   The developing roller according to claim 1, wherein the fatty acid is 12-hydroxystearic acid. In an electrophotographic process cartridge detachably attached to an electrophotographic image forming apparatus provided with a developing roller for supplying a toner to the surface of an electrostatic latent image carrier to develop the electrostatic latent image to form a toner image ,
Electrophotographic process cartridge, wherein the developing roller is the developing roller according to claim 1 or 2. In an electrophotographic image forming apparatus provided with a developing roller for supplying a toner to the surface of an electrostatic latent image carrier and developing the electrostatic latent image to form a toner image,
Electrophotographic image forming apparatus, wherein the developing roller is the developing roller according to claim 1 or 2.

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