JP2010204134A - Developing roller, electrophotographic process cartridge using the developing roller, and electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller which suppresses deformation due to pressure from other members, and can obtain a high-quality image over a long period, while improving a charge applying property to toner. <P>SOLUTION: On a mandrel and the periphery of the mandrel, at least one elastic layer is provided and a resin layer is provided on an outer peripheral surface of the elastic layer. The resin layer includes at least etherified melamine resin having a unit represented by a general formula (1), resin particles, and carbon black. In the formula, R represents an alkyl group having a carbon number of 5 to 8. R' represents an alkyl group having a carbon number of 1 to 3. Also, "*" represents a repetitive bond. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  As a developing method in an electrophotographic image forming apparatus, a one-component developing method using a one-component developer (toner) and a two-component developing method using a two-component developer are known. The one-component development method is advantageous for reduction in size and weight. The one-component development method is roughly divided into a magnetic one-component development method that contains a magnetic material in a developer and a non-magnetic one-component development method that does not contain a magnetic material. Since magnetic materials are usually colored, non-magnetic one-component development methods are used for full-color printers.

  In a developing device using a non-magnetic one-component developing method, a developing roller is provided so as to close an opening of a toner container for storing toner and to expose a part of the toner container outside. The toner is supplied onto the surface of the developing roller by an elastic roller provided in contact with the developing roller in the toner container. Subsequently, the excess amount is removed by the toner amount regulating member, and the toner is formed in a uniform thin film on the developing roller, and at the same time, positive or negative charge is given to the toner by friction. Further, the toner charged positively or negatively by the rotation of the developing roller is transported to the developing area of the exposed portion, where it adheres to the electrostatic latent image on the surface of the photosensitive drum that is provided opposite thereto, and is developed. At this time, if charge is not properly applied to the toner, the toner does not adhere as the electrostatic latent image on the surface of the photosensitive drum, and a desired image cannot be obtained. In addition, when the electrophotographic image forming apparatus is left unused for a long period of time, the developing roller continuously receives pressure from other members such as a toner amount regulating member and a photosensitive drum at a certain position, thereby developing the surface of the developing roller. Deformation occurs in the vicinity. This deformation becomes a factor that hinders the formation of a uniform thin film when the toner thin film is formed by the toner amount regulating member. As a result, the amount of toner supplied to the photosensitive drum largely fluctuates in the deformed portion, so that an image defect of the developing roller period occurs on the image.

  In order to satisfy such various required characteristics, the developing roller generally has a multi-layer structure, and each layer has a function, functions are separated, and various characteristics necessary for the developing roller are achieved. It has been.

  Among the characteristics, as one of methods for improving the charge imparting property, a method of providing a melamine resin as the outermost layer on the outer periphery of the developing roller is disclosed (Patent Documents 1, 2, and 3). However, when melamine resin is used for the outermost layer, the hardness of the roller surface increases and the durability tends to decrease. In addition, since the shape of the roller is always deformed by contact with other members in the developing roller used for contact development, flexibility that can follow the deformation is also required. However, as described above, the hardness of the roller surface is required for melamine resin. Therefore, it is difficult to ensure the flexibility of the developing roller.

JP 2001-132730 A JP 2004-184661 A JP 2007-025593 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing roller capable of improving the charge imparting property to toner and at the same time suppressing deformation due to pressing from other members and obtaining a high-quality image over a long period of time. . It is another object of the present invention to provide an electrophotographic process cartridge and an electrophotographic image forming apparatus that can obtain a high-quality image over a long period of time by using this.

  When the present inventors use an etherified melamine resin having a specific unit in the resin component of the resin layer that forms the outermost surface of the developing roller, deformation due to pressing from other members can be suppressed, and at the same time, It has been found that the charge imparting property can be maintained over a long period of time. Based on this knowledge, the present invention has been completed.

  That is, the present invention provides a developing roller comprising a shaft core body, at least one elastic layer around the shaft core body, and a resin layer on the outer peripheral surface of the elastic layer. 1. A developing roller comprising a resin component comprising an etherified melamine resin having a unit represented by 1), resin particles, and carbon black.

（式中、Ｒは炭素数５乃至８のアルキル基を示す。Ｒ’は炭素数1乃至３のアルキル基を示す。また、＊は繰り返しの結合を表す。）

(In the formula, R represents an alkyl group having 5 to 8 carbon atoms. R ′ represents an alkyl group having 1 to 3 carbon atoms. * Represents a repeated bond.)

  The present invention also relates to a rotatable photosensitive drum, a charging member that contacts the photosensitive drum and charges the surface of the photosensitive drum, and a developer that contacts the photosensitive drum and that contacts the surface of the photosensitive drum by a developing roller. An electrophotographic process cartridge having a developing member that develops an electrostatic latent image by developing the electrostatic latent image, wherein the developing roller is the developing roller.

  The present invention also provides a rotatable photosensitive drum, a charging member that contacts the photosensitive drum and charges the surface of the photosensitive drum, an exposure unit that forms an electrostatic latent image on the surface of the photosensitive drum, and the photosensitive drum. A developing member that contacts the drum and supplies a developer to the surface of the photosensitive drum by a developing roller to develop the electrostatic latent image into a developer image; and a transfer member that transfers the developer image to a transfer material; An electrophotographic apparatus comprising: a fixing member that fixes a developer image transferred onto the transfer material; and a pressure member that forms a nip portion with the fixing member and conveys the transfer material while being pressed by the nip portion. In the image forming apparatus, the developing roller is the developing roller.

  The developing roller of the present invention is compatible with both suppression of deformation due to pressing from other members and maintaining high charge-imparting properties over a long period of time. As a result, high quality image quality can be obtained over a long period of time. In addition, the electrophotographic process cartridge and the electrophotographic image forming apparatus of the present invention can obtain high quality images over a long period of time.

It is a schematic sectional drawing which shows an example of the developing roller of this invention. 1 is a schematic configuration diagram showing an electrophotographic image forming apparatus of the present invention. 1 is a cross-sectional configuration diagram illustrating an electrophotographic process cartridge of the present invention. It is the schematic explaining the sample for measuring the thickness of a resin layer.

  An example of the configuration of the developing roller of the present invention is shown in FIG. FIG. 1A shows a cross-sectional view in the longitudinal direction of the developing roller, and FIG. 1B shows a cross-sectional view perpendicular to the longitudinal direction of the developing roller.

  This developing roller has a structure in which at least one conductive elastic layer 12 and a resin layer 13 are sequentially laminated on the outer peripheral surface of the elastic layer 12 on a shaft core 11.

  The shaft core 11 used in the developing roller of the present invention may support any conductive upper elastic layer 12 and resin layer 13 as long as it has conductivity. As the material, carbon steel, alloy steel, cast iron, carbon black, or conductive resin obtained by solidifying carbon fiber with plastic can be appropriately selected and used. Examples of the alloy steel include stainless steel, nickel chrome steel, nickel chrome molybdenum steel, chrome steel, chromium molybdenum steel, nitride steel added with Al, Cr, Mo, and V.

  Furthermore, as the shaft core 11, a rod or pipe made of the above-mentioned material and subjected to rust prevention treatment such as plating or oxidation treatment can be used. As the type of plating, both electroplating and electroless plating can be used, but electroless plating is preferable from the viewpoint of dimensional stability. Examples of the electroless plating used here include nickel plating (Kanizen plating), copper plating, gold plating, and other various alloy platings. Examples of the nickel plating include Ni-P, Ni-B, Ni-WP, and Ni-P-PTFE composite plating. The plating thickness can be, for example, 0.05 μm or more, but considering the balance between work efficiency and rust prevention capability, the plating thickness is suitably 0.1 μm or more and 30 μm or less.

  Examples of the shape of the shaft body include a rod shape and a pipe shape. A primer treatment layer may be formed on the surface as necessary. The outer diameter of the shaft core is suitably in the range of 4 mm to 20 mm, for example.

  Examples of the material of the conductive elastic layer 12 provided on the outer periphery of the shaft core 11 include fluoro rubber, urethane rubber, silicone rubber, natural rubber, isoprene rubber, styrene rubber, butyl rubber, and butadiene rubber. These materials may be used alone or in combination of two or more. Furthermore, foams of these materials may be used for the conductive elastic layer.

  The conductive elastic layer 12 preferably has a hardness (Asker C hardness) of 20 degrees or more and 60 degrees or less. If the hardness of the conductive elastic layer 12 is 20 degrees or more, the roller can be prevented from being extremely deformed when the toner amount regulating member comes into contact, and the toner can be uniformly thinned on the roller. Further, if the hardness of the conductive elastic layer 12 is 60 degrees or less, the toner to be conveyed is hardly damaged, and the deterioration of the image quality of the output image can be suppressed.

  The measuring method of the hardness (AskerC hardness) of a conductive elastic layer is shown. Asker C hardness is a hardness measured using an ASKER-C spring rubber hardness meter (trade name, manufactured by Kobunshi Keiki Co., Ltd.) in accordance with the Japan Rubber Association standard SRIS0101. After the developing roller to be measured is left in an environment of 23 ° C. and 55% RH for 24 hours or longer, the hardness meter is brought into contact with the central portion of the developing roller and the position 50 mm from both ends with a force of 9.8 N. The measured value after 30 seconds is obtained. The arithmetic average value of the measured values obtained from these three points is taken as the hardness of the developing roller.

Since the conductive elastic layer 12 has conductivity, it contains a conductivity-imparting agent based on an ionic conduction mechanism or an electronic conduction mechanism. The following can be used as the conductivity-imparting agent by the ionic conduction mechanism.
A salt of a Group I metal of the periodic table (LiCF ₃ SO ₃ , NaClO ₄ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , NaSCN, KSCN, NaCl, etc.).
-Group II metal salts of the periodic table (Ca (ClO ₄ ) ₂ , Ba (ClO ₄ ) ₂ etc.).
Ammonium salt _{(NH 4 Cl, (NH 4} ) 2 SO 4, NH 4 NO 3 , etc.).
-Complex of the above salt with polyhydric alcohol (1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, etc.)-Salt and monool (ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, polyethylene) Glycol monomethyl ether, polyethylene glycol monoethyl ether, etc.), cationic surfactants, anionic surfactants, amphoteric surfactants.

Moreover, the following can be mentioned as an electroconductivity imparting agent by an electronic conduction mechanism.
-Carbonaceous materials (carbon black, graphite, etc.).
・ Metals and alloys (aluminum, silver, gold, tin-lead alloy, copper-nickel alloy, etc.).
-Metal oxides (zinc oxide, titanium oxide, aluminum oxide, tin oxide, antimony oxide, indium oxide, silver oxide, etc.).
-Further, a substance obtained by applying a conductive metal plating such as copper, nickel, silver, etc. to the above-mentioned conductivity-imparting agent.

  These conductivity-imparting agents based on the ion conduction mechanism and the electron conduction mechanism can be used alone or in combination of two or more in a powdery or fibrous form. Among these, carbon black is preferable from the viewpoint of easy control of conductivity and economy.

The volume resistivity of the conductive elastic layer 12 is preferably in the range of 1 × 10 ⁴ Ω · cm to 1 × 10 ¹¹ Ω · cm because the toner can be uniformly charged. A more preferable range of the volume resistivity of the conductive elastic layer 12 is 1 × 10 ⁴ Ω · cm to 1 × 10 ⁹ Ω · cm.

The volume resistivity of the conductive elastic layer 12 can be measured under the following conditions using a digital ultrahigh resistance / microammeter “8340A” (trade name, manufactured by ADC Corporation) as a resistance meter.
Measurement mode: Program mode 5
(Charge and major 30 seconds, discharge 10 seconds)
Applied voltage: 100 (V)
Sample box: Resistivity chamber 42 (trade name, manufactured by ADC Corporation)
Main electrode: metal with a diameter of 22 mm and a thickness of 10 mm Guard ring electrode: metal with an inner diameter of 41 mm, an outer diameter of 49 mm, and a thickness of 10 mm Test piece: First, a conductive elastic layer material is formed into a sheet shape and is conductive under the same conditions as the molding conditions The elastic layer material is cured to produce a rubber sheet having a thickness of 2.0 mm. Next, a test piece having a diameter of 56 mm is cut out from the produced rubber sheet. A vapor-deposited film electrode (back surface electrode) is provided on one surface of the cut test piece by vapor deposition of Pt—Pd on the entire surface. Similarly, a main electrode film having a diameter of 25 mm and a guard ring electrode film having an inner diameter of 38 mm and an outer diameter of 50 mm are provided concentrically on the other surface by a Pt—Pd vapor deposition film. The Pt—Pd vapor-deposited film is obtained by performing a vapor deposition operation for 2 minutes at a current value of 15 mA using mild sputter E1030 (trade name, manufactured by Hitachi, Ltd.). The sample after the vapor deposition operation is used as a measurement sample.

At the time of measurement, the main electrode having a diameter of 22 mm is placed so as not to protrude from the main electrode film having a diameter of 25 mm. Further, the measurement is performed by placing a guard ring electrode having an inner diameter of 41 mm on the electrode film so as not to protrude from the guard ring electrode film having an inner diameter of 38 mm and an outer diameter of 50 mm. The measurement is performed in an environment of a temperature of 23 ° C. and a humidity of 55% RH. Before measurement, leave the measurement sample in the same environment for 24 hours or more. In the above state, the volume resistance (Ω) of the test piece is measured. Next, the volume resistivity RR (Ω · cm) of the test piece is obtained from the measured volume resistance value RM (Ω) and the thickness t (cm) of the test piece by the following equation.
RR (Ω · cm) = π × 1.25 × 1.25 × RM (Ω) ÷ t (cm)

  The conductive elastic layer 12 has a plasticizer, a filler, an extender, a vulcanizing agent, a cross-linking agent, a vulcanizing aid, a cross-linking aid, an antioxidant as long as it does not impair the function of the above composition. Various additives such as an agent, an anti-aging agent and a processing aid can be contained.

  The thickness of the conductive elastic layer 12 can be appropriately selected so as to have a desired elasticity in relation to the material, the toner amount regulating member, the photosensitive drum, and the like, for example, 1.0 mm to 5.0 mm. be able to. In addition, even if this elastic layer is one layer, in order to share each function as needed, it is good also as two or more layers.

  In the present invention, a resin layer 13 is further provided on the outer peripheral surface of the conductive elastic layer 12 for the purpose of adjusting characteristics such as resistance, roughness, and hardness.

  The resin layer 13 in the developing roller of the present invention includes at least an etherified melamine resin having a unit represented by the general formula (1), resin particles, and carbon black.

（式中、Ｒは炭素数５乃至８のアルキル基を示す。Ｒ’は炭素数1乃至３のアルキル基を示す。また、＊は繰り返しの結合を表す。）

(In the formula, R represents an alkyl group having 5 to 8 carbon atoms. R ′ represents an alkyl group having 1 to 3 carbon atoms. * Represents a repeated bond.)

  Moreover, the resin component which consists of an etherified melamine resin which has a unit shown by at least General formula (1) can be obtained by heating and making the etherified melamine shown by General formula (2) react.

（式中、Ｒは炭素数５乃至８のアルキル基を示す。Ｒ’は炭素数1乃至３のアルキル基を示す。）

(In the formula, R represents an alkyl group having 5 to 8 carbon atoms. R ′ represents an alkyl group having 1 to 3 carbon atoms.)

  The etherified melamine represented by the general formula (2) is a preparation example of a butylated melamine resin of Comparative Production Example 1 of JP-A-9-208221, JP-A-8-283364 and JP-A-8-92226. It can be synthesized according to the synthesis method of methylated melamine resin. Moreover, in this invention, it aims at making high charging provision and suppression of the deformation | transformation by the long-term press from another member paying attention to the etherified melamine resin shown by General formula (1), Tried to improve. In the study, the alkyl group represented by R in the general formula (1) has 5 to 8 carbon atoms, and the alkyl group represented by R ′ has 1 to 3 carbon atoms. I found it important.

  When each value is within this range, by using an etherified melamine resin having a unit represented by the general formula (1) as a resin component of the resin layer of the developing roller, appropriate flexibility and high charge imparting property can be obtained. It is possible to achieve both. Appropriate flexibility here refers to hardness that can prevent deformation due to long-term pressing from other members, and flexibility that can follow distortion that occurs when rotating while contacting other members during the development process. Can be achieved at the same time.

  Here, when the carbon number of R is 4 or less and the carbon number of R ′ is 0, the etherified melamine resin represented by the general formula (1) greatly contributes to the hardening of the resin layer. Get higher. Therefore, when the resin layer is formed, the resin layer becomes brittle, and there is a problem in durability as the resin layer of the developing roller that rotates while contacting with other members during the image forming process.

  On the other hand, when the carbon number of R is 9 or more and the carbon number of R ′ is 4 or more, the contribution to the softening of the resin layer is increased, and deformation due to long-term pressing from other members is suppressed. Presumed to be impossible.

  Moreover, it is also possible to form a resin layer in combination with another resin material having a reactive group (for example, a hydroxyl group) capable of reacting with the general formula (2). At that time, the content of the etherified melamine resin of the general formula (1) contained in the resin component of the resin layer is preferably 20% by mass or more and 50% by mass or less. By setting the content of the etherified melamine resin to 20% by mass or more in the resin component, it is possible to sufficiently exhibit appropriate flexibility and high charge imparting characteristics. Moreover, the characteristic of another combined resin material can fully be expressed by setting it as 50 mass% or less.

  The resin layer 13 can contain resin particles. The resin particles are used to make the surface roughness suitable for toner conveyance. The surface roughness of the resin layer 13 is preferably 3.0 μm or less in terms of surface roughness Ra (JIS B0601: 2001). When Ra is 3.0 μm or less, it is possible to suppress an excessive toner conveyance amount and to suppress deterioration of an image due to toner remaining on the photosensitive drum. Since the resin particles are more familiar with the resin component than the inorganic particles, the resin particles can be uniformly dispersed in the resin layer and the roughness distribution on the surface of the developing roller can be made uniform.

  The role of the resin layer 13 is to impart conductivity. For this reason, as the conductive agent used for the resin layer 13, carbon black that is easy to control the conductivity is used. At this time, the amount of carbon black contained in the resin component is preferably 10% by mass or more and 30% by mass or less with respect to the resin component contained in the resin layer 13. When the content of carbon black is 10% by mass or more, the conductivity as the resin layer of the developing roller can be sufficiently ensured. Moreover, by setting it as 30 mass% or less, it can prevent that a resin layer becomes hard too much and becomes weak by the reinforcement effect of the resin layer by carbon black.

  The thickness of the resin layer 13 is preferably 2 μm or more and 8 μm or less. If the thickness is 2 μm or more, the resin layer 13 has sufficient wear resistance, and if it is 8 μm or less, the resin layer 13 can be prevented from becoming extremely hard and damage to the toner can be suppressed. .

  The conductive elastic layer 12 of such a developing roller can be formed on the shaft core 11 by a method such as an extrusion method, a mold method, or an injection molding method. Of these methods, a mold method is used. Is preferred. The mold forming method is useful because a conductive elastic layer with high shape accuracy can be obtained efficiently and at low cost by continuous production as compared with other forming methods. Note that the surface of the conductive elastic layer 12 is modified by a surface modification method such as corona treatment, frame treatment, or excimer treatment in order to improve adhesion with the resin layer 13 provided thereon. Is preferred.

  Examples of a method for forming a resin layer on the conductive elastic layer include a method by coating. As a coating method, a dipping method, a roll coating method, a ring coating method, a spray coating method, or the like using a coating solution prepared by dissolving or dispersing a resin component, resin particles, and carbon black in a solvent is suitable. Among these coating methods, it is preferable to use the dipping method because the thickness is easily controlled and the production is easy. In the dipping method, the viscosity of the coating liquid is preferably 5 mPa · s or more and 50 mPa · s or less. By setting the viscosity to 5 mPa · s or more, the shape is not collapsed until the coating film is cured, and it can be produced as a stable shape. In addition, when the viscosity of the coating liquid is 50 mPa · s or less, it is easy to form a uniform film thickness with excellent coating properties. In order to obtain such a viscosity, the solvent to be used and the amount thereof can be appropriately selected.

The following are mentioned as a solvent.
・ Alcohols (methanol, ethanol, isopropanol, etc.)
-Ketones (acetone, methyl ethyl ketone, cyclohexanone, etc.)
Amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.)
・ Sulphoxides (dimethyl sulfoxide, etc.)
・ Ethers (tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, etc.)
・ Esters (methyl acetate, ethyl acetate, etc.)
・ Aromatic compounds (xylene, etc.)

  Next, the electrophotographic process cartridge and the electrophotographic image forming apparatus of the present invention will be described.

In general, an electrophotographic image forming apparatus includes a rotatable photosensitive drum and the following members.
A charging member that contacts the photosensitive drum and uniformly charges the surface of the photosensitive drum. Exposure means for recording image information (forms an electrostatic latent image) on the surface of the photosensitive drum. A developing member (hereinafter also referred to as a “developing device”) for supplying the developer to the surface of the photosensitive drum by a developing roller and developing the electrostatic latent image into a developer image.
A transfer member for transferring the developer image to a transfer material. A fixing member for fixing the developer image transferred onto the transfer material. A nip portion is formed with the fixing member, and the transfer is performed by the nip portion. Pressurizing member that conveys the material in pressure contact

  As an example, FIG. 2 shows a schematic configuration of an electrophotographic image forming apparatus using an electrophotographic process cartridge provided with the developing roller of the present invention.

  The electrophotographic image forming apparatus shown in FIG. 2 is a tandem color image forming apparatus that forms black, cyan, magenta, and yellow images, and is provided with an electrophotographic process cartridge corresponding to each color. The electrophotographic process cartridge has the same basic configuration although there are differences in specifications and the like corresponding to each color. In the following, these common configurations will be described. FIG. 3 is a schematic cross-sectional view of one electrophotographic process cartridge taken out.

  As described above, the developing device 205 including the developing roller 201 includes the developing roller 201, the toner supply roller 202, the toner (developer) 203, and the toner amount regulating member 204. The electrophotographic process cartridge that can be attached to and detached from the electrophotographic image forming apparatus includes a developing drum 205, a photosensitive drum 206, a cleaning blade 207, a waste toner container 208, and a charging member 209. The electrophotographic process cartridge reaches the end of its life by performing image output a certain number of times. Thereafter, the electrophotographic process cartridge is replaced with a new one, and the electrophotographic image forming apparatus can output an image again.

  The developing device 205 includes a developing container that contains toner 203 and a developing roller 201 that is positioned in an opening extending in the longitudinal direction in the developing container and is disposed opposite to the photosensitive drum 206. The electrostatic latent image is developed and visualized.

  The toner supply roller 202 has a foamed skeleton-like sponge structure or a fur brush structure in which fibers such as rayon and polyamide are planted on the shaft core, and is used for supplying toner to the developing roller 201 and stripping off undeveloped toner. To preferred. For example, an elastic roller in which polyurethane foam is provided on the shaft core can be used.

  Here, the image forming process up to image output will be described in detail. The photosensitive drum 206 rotates in the direction of the arrow and is uniformly charged by a charging member 209 for charging the photosensitive drum 206. Next, an electrostatic latent image is formed by exposure means 210 (for example, laser light) that writes the electrostatic latent image on the photosensitive drum 206. The electrostatic latent image is developed by applying toner by the developing device 205 disposed in contact with the photosensitive drum 206, and visualized as a toner image.

  The visualized toner image on the photosensitive drum 206 is transferred by the transfer member 211 to the recording paper 212 sent in synchronization with the rotation of the photosensitive drum 206. The recording paper 212 onto which the toner image has been transferred is fixed by the fixing member 213 and discharged outside the apparatus, and a series of image forming processes is completed. The recording paper 212 is carried on a conveyance belt and is conveyed in synchronization with the formation of a toner image. On the recording paper 212, toner images of respective colors are sequentially stacked to form a color toner image. After the toner image is superimposed and transferred by the last image forming apparatus, the toner image is peeled off from the conveying belt, sent to the fixing member 213, and batch fixing processing is performed to form a color image.

  On the other hand, toner remaining on the surface of the photosensitive drum 206 without being transferred to the recording paper is scraped off by a cleaning blade 207, and the scraped toner is stored in a waste toner container 208. On the other hand, the cleaned photosensitive drum 206 is prepared for the next image formation.

  Hereinafter, the developing roller, the electrophotographic process cartridge, and the electrophotographic image forming apparatus of the present invention will be described in detail with reference to examples, but the technical scope of the present invention is not limited thereto. In the following, unless otherwise specified, parts represent parts by mass, and reagents and the like used were commercially available high-purity products.

  First, a method for synthesizing the etherified melamine used in this example is shown.

Production Example 1 [Synthesis of Etherified Melamine X-1]
A four-necked flask equipped with a condenser, a stirrer, and a thermometer was charged with 126 parts of melamine, 308.4 parts of acetaldehyde, and 705.6 parts of pentyl alcohol, and the pH was adjusted to 6.0. Thereafter, the temperature was heated to 70 ° C. with stirring to carry out an ethylolation reaction. 20 minutes after the temperature reached 70 ° C., the pH was adjusted to 3.0. Thereafter, the temperature was maintained at 70 ° C., and an etherification reaction was performed for 5 hours. Thereafter, the pH was adjusted to 7.0, and unreacted acetaldehyde, pentyl alcohol and water were distilled off under reduced pressure until the nonvolatile content reached 98%. For adjusting the pH, an aqueous solution of hydrochloric acid and caustic soda having appropriate concentrations was used.

  Thereafter, the mixture was diluted with ethylene glycol monobutyl ether, and the precipitated salts were separated by filtration. Further, it was diluted with ion-exchanged water to obtain an aqueous solution of etherified melamine X-1 (in formula (2), R = C5 alkyl group, R ′ = C1 alkyl group).

Production Example 2 [Synthesis of Etherified Melamine X-2]
A four-necked flask equipped with a condenser, a stirrer and a thermometer was charged with 126 parts of melamine, 385.6 parts of propionaldehyde and 817.5 parts of hexyl alcohol, and the pH was adjusted to 6.0. Thereafter, the temperature was heated to 70 ° C. with stirring to carry out a propylolation reaction. 20 minutes after the temperature reached 70 ° C., the pH was adjusted to 3.0. Thereafter, the temperature was maintained at 70 ° C., and an etherification reaction was performed for 5 hours. Thereafter, the pH was adjusted to 7.0, and unreacted propionaldehyde, hexyl alcohol and water were distilled off under reduced pressure until the nonvolatile content reached 98%. For adjusting the pH, an aqueous solution of hydrochloric acid and caustic soda having appropriate concentrations was used.

  Thereafter, the mixture was diluted with ethylene glycol monobutyl ether, and the precipitated salts were separated by filtration. Further, it was diluted with ion-exchanged water to obtain an aqueous solution of etherified melamine X-2 (in formula (2), R = C6 alkyl group, R ′ = C2 alkyl group).

Production Example 3 [Synthesis of Etherified Melamine X-3]
A four-necked flask equipped with a condenser, a stirrer, and a thermometer was charged with 126 parts of melamine, 228.3 parts of acetaldehyde, and 1041.9 parts of octyl alcohol, and the pH was adjusted to 6.0. Thereafter, the temperature was heated to 70 ° C. with stirring to carry out an ethylolation reaction. 20 minutes after the temperature reached 70 ° C., the pH was adjusted to 3.0. Thereafter, the temperature was maintained at 70 ° C., and an etherification reaction was performed for 5 hours. Thereafter, the pH was adjusted to 7.0, and unreacted acetaldehyde, octyl alcohol and water were distilled off under reduced pressure until the nonvolatile content reached 98%. For adjusting the pH, an aqueous solution of hydrochloric acid and caustic soda having appropriate concentrations was used.

  Thereafter, the mixture was diluted with ethylene glycol monobutyl ether, and the precipitated salts were separated by filtration. Further, it was diluted with ion-exchanged water to obtain an aqueous solution of etherified melamine X-3 (in general formula (2), R = C8 alkyl group, R ′ = C1 alkyl group).

Production Example 4 [Synthesis of Etherified Melamine X-4]
A four-necked flask equipped with a condenser, a stirrer, and a thermometer was charged with 126 parts of melamine, 504.8 parts of butyraldehyde and 705.6 parts of pentyl alcohol, and the pH was adjusted to 6.0. Then, the temperature was heated to 70 ° C. with stirring, and a butyroylation reaction was performed. 20 minutes after the temperature reached 70 ° C., the pH was adjusted to 3.0. Thereafter, the temperature was maintained at 70 ° C., and an etherification reaction was performed for 5 hours. Thereafter, the pH was adjusted to 7.0, and unreacted butyraldehyde, pentyl alcohol and water were distilled off under reduced pressure until the nonvolatile content reached 98%. For adjusting the pH, an aqueous solution of hydrochloric acid and caustic soda having appropriate concentrations was used.

  Thereafter, the mixture was diluted with ethylene glycol monobutyl ether, and the precipitated salts were separated by filtration. Further, it was diluted with ion-exchanged water to obtain an aqueous solution of etherified melamine X-4 (in the general formula (2), R = C5 alkyl group, R ′ = C3 alkyl group).

Production Example 5 [Synthesis of Etherified Melamine X-5]
A four-necked flask equipped with a condenser, a stirrer, and a thermometer was charged with 126 parts of melamine, 504.8 parts of butyraldehyde, and 1041.9 parts of octyl alcohol, and the pH was adjusted to 6.0. Then, the temperature was heated to 70 ° C. with stirring, and a butyroylation reaction was performed. 20 minutes after the temperature reached 70 ° C., the pH was adjusted to 3.0. Thereafter, the temperature was maintained at 70 ° C., and an etherification reaction was performed for 5 hours. Thereafter, the pH was adjusted to 7.0, and unreacted butyraldehyde, octyl alcohol and water were distilled off under reduced pressure until the nonvolatile content reached 98%. For adjusting the pH, an aqueous solution of hydrochloric acid and caustic soda having appropriate concentrations was used.

  Thereafter, the mixture was diluted with ethylene glycol monobutyl ether, and the precipitated salts were separated by filtration. Further, it was diluted with ion-exchanged water to obtain an aqueous solution of etherified melamine X-5 (in general formula (2), R = C8 alkyl group, R ′ = C3 alkyl group).

Production Example 6 [Synthesis of Etherified Melamine X-6]
A four-necked flask equipped with a condenser, a stirrer, and a thermometer was charged with 126 parts of melamine, 210.1 parts of formaldehyde, and 705.6 parts of pentyl alcohol, and the pH was adjusted to 6.0. Thereafter, the temperature was heated to 70 ° C. with stirring to carry out a methylolation reaction. 20 minutes after the temperature reached 70 ° C., the pH was adjusted to 3.0. Thereafter, the temperature was maintained at 70 ° C., and an etherification reaction was performed for 5 hours. Thereafter, the pH was adjusted to 7.0, and unreacted formaldehyde, pentyl alcohol and water were distilled off under reduced pressure until the nonvolatile content reached 98%. For adjusting the pH, an aqueous solution of hydrochloric acid and caustic soda having appropriate concentrations was used.

  Thereafter, the mixture was diluted with ethylene glycol monobutyl ether, and the precipitated salts were separated by filtration. Further, the solution was diluted with ion-exchanged water to obtain an aqueous solution of etherified melamine X-6 (in the general formula (2), R = C5 alkyl group, R ′ = C0 alkyl group = H).

Production Example 7 [Synthesis of Etherified Melamine X-7]
A four-necked flask equipped with a condenser, a stirrer and a thermometer was charged with 126 parts of melamine, 308.4 parts of acetaldehyde and 593.0 parts of n-butyl alcohol, and the pH was adjusted to 6.0. Thereafter, the temperature was heated to 70 ° C. with stirring to carry out an ethylolation reaction. 20 minutes after the temperature reached 70 ° C., the pH was adjusted to 3.0. Thereafter, the temperature was maintained at 70 ° C., and an etherification reaction was performed for 5 hours. Thereafter, the pH was adjusted to 7.0, and unreacted acetaldehyde, n-butyl alcohol and water were distilled off under reduced pressure until the nonvolatile content reached 98%. For adjusting the pH, an aqueous solution of hydrochloric acid and caustic soda having appropriate concentrations was used.

  Thereafter, the mixture was diluted with ethylene glycol monobutyl ether, and the precipitated salts were separated by filtration. Further, it was diluted with ion-exchanged water to obtain an aqueous solution of etherified melamine X-7 (in the general formula (2), R = C4 alkyl group, R ′ = C1 alkyl group).

Production Example 8 [Synthesis of Etherified Melamine X-8]
A four-necked flask equipped with a condenser, a stirrer, and a thermometer was charged with 126 parts of melamine, 210.1 parts of formaldehyde, and 1041.9 parts of octyl alcohol, and the pH was adjusted to 6.0. Thereafter, the temperature was heated to 70 ° C. with stirring to carry out a methylolation reaction. 20 minutes after the temperature reached 70 ° C., the pH was adjusted to 3.0. Thereafter, the temperature was maintained at 70 ° C., and an etherification reaction was performed for 5 hours. Thereafter, the pH was adjusted to 7.0, and unreacted formaldehyde, octyl alcohol and water were distilled off under reduced pressure until the nonvolatile content reached 98%. For adjusting the pH, an aqueous solution of hydrochloric acid and caustic soda having appropriate concentrations was used.

  Thereafter, the mixture was diluted with ethylene glycol monobutyl ether, and the precipitated salts were separated by filtration. Further, it was diluted with ion-exchanged water to obtain an aqueous solution of etherified melamine X-8 (in the general formula (2), R = C8 alkyl group, R ′ = C0 alkyl group = H).

Production Example 9 [Synthesis of Etherified Melamine X-9]
A four-necked flask equipped with a condenser, a stirrer, and a thermometer was charged with 126 parts of melamine, 504.8 parts of butyraldehyde and 593 parts of n-butyl alcohol, and the pH was adjusted to 6.0. Then, the temperature was heated to 70 ° C. with stirring, and a butyroylation reaction was performed. 20 minutes after the temperature reached 70 ° C., the pH was adjusted to 3.0. Thereafter, the temperature was maintained at 70 ° C., and an etherification reaction was performed for 5 hours. Thereafter, the pH was adjusted to 7.0, and unreacted butyraldehyde, n-butyl alcohol and water were distilled off under reduced pressure until the nonvolatile content reached 98%. For adjusting the pH, an aqueous solution of hydrochloric acid and caustic soda having appropriate concentrations was used.

  Thereafter, the mixture was diluted with ethylene glycol monobutyl ether, and the precipitated salts were separated by filtration. Further, it was diluted with ion-exchanged water to obtain an aqueous solution of etherified melamine X-9 (in the general formula (2), R = C4 alkyl group, R ′ = C3 alkyl group).

Production Example 10 [Production of Raw Material Roller Having Conductive Elastic Layer]
A shaft made of SUS304 with a diameter of 8 mm is nickel-plated, and a primer DY39-051 (trade name, manufactured by Toray Dow Corning Co.) with a thickness of about 1 μm is applied and baked at a temperature of 150 ° C. for 30 minutes. Using. Next, the shaft core is placed in a mold, and liquid silicone rubber materials SE6274A (trade name, manufactured by Toray Dow Corning Silicone) and SE6274B (trade name, manufactured by Toray Dow Corning) are statically mixed at a weight ratio of 1: 1. Mix using a mixer. Thereafter, the mixed liquid silicone rubber was injected into a cavity formed in the mold. Subsequently, the mold was heated to cure and cure the liquid silicone rubber at a temperature of 150 ° C. for 15 minutes, and after cooling, the mold was removed. Thereafter, the material was further heated at a temperature of 180 ° C. for 2 hours to complete the curing reaction, thereby obtaining a raw material roller provided with a conductive elastic layer around the shaft core body. The diameter of the raw material roller was 16 mm.

[Example 1] [Production of developing roller 1]
[Preparation of coating solution for resin layer]
As resin components, 100 parts of acrylic polyol (trade name: H3368, manufactured by Hitachi Chemical Co., Ltd.) and 42.9 parts (solid content) of etherified melamine X-1 (produced in Production Example 1) were prepared. For 100 parts of this resin component, 23 parts of carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Corporation) and 30 parts of resin particles (trade name: C400 transparent, manufactured by Negami Kogyo Co., Ltd.) are added to methyl ethyl ketone (MEK). Was added to obtain a mixed solution.

Subsequently, the above mixed solution is uniformly dispersed for 2 hours using a horizontal disperser NVM-03 (trade name, manufactured by IMEX Co., Ltd.) under conditions of a peripheral speed of 7 m / s, a flow rate of 1.7 cm ³ / s, and a dispersion temperature of 15 ° C. Then, the mixture was filtered through a 380 mesh screen to obtain a resin layer coating solution.

[Formation of resin layer]
Next, the inside of a cylinder having a diameter of 32 mm was filled with the coating liquid, and the coating liquid in the cylinder was circulated at a flow rate of 4.0 cm ³ / s and a liquid temperature of 23 ° C. At this time, MEK was added to the coating solution to adjust the viscosity of the coating solution. Thereafter, a raw material roller (produced in Production Example 10) having a conductive elastic layer in the cylinder was immersed at an intrusion speed of 100 mm / s. After stopping for 10 seconds in a state where the entire elastic layer was immersed, the elastic layer was pulled up under conditions of an initial speed of 300 mm / s and an final speed of 200 mm / s and naturally dried for 10 minutes. Next, heat treatment was performed at a temperature of 160 ° C. for 2 hours to cure the coating layer, and a resin layer was formed to obtain the developing roller 1.

  The film thickness of the resin layer of the developing roller was measured according to the following procedure. Using a razor, a half-moon shaped sample composed of an elastic layer 41 and a resin layer 42 as shown in FIG. 4 was cut out from the central portion in the longitudinal direction of the developing roller and 50 mm from both ends. About each sample, ten thicknesses of the resin layer 42 were measured using the optical microscope, changing the place. At this time, a portion where no resin particles exist was selected and measured. For one developing roller, three samples (the central portion of the developing roller, 50 mm from both ends) × 10 points = the arithmetic average value of the resin layer thicknesses of a total of 30 points were obtained, and the value was calculated as the resin layer thickness of the developing roller. did.

  Further, using the obtained developing roller 1, the initial density of the formed image, the durability of the developing roller 1, the surface contamination, and the deformation amount were measured and evaluated as follows. The results are shown in Table 1.

[Initial density of image]
The developing roller was incorporated into an electrophotographic process cartridge, and initial density evaluation was performed. When performing this evaluation, an electrophotographic image forming apparatus “LBP5500” (trade name, manufactured by Canon Inc.) was used, and an EP-85 toner cartridge (black) dedicated to this apparatus was used as an electrophotographic process cartridge.

The electrophotographic process cartridge incorporating the developing roller was left in an environment of 25 ° C. and 45% RH for 24 hours, and then mounted on the main body of the electrophotographic image forming apparatus in the same environment to output a solid black image. Using the spectral densitometer “504JP” (trade name, manufactured by X-Rite Co., Ltd.), the image density is 9 points at the top, center, and bottom of the output image. The arithmetic mean value was taken as the initial density of the image. Based on the measurement results, the following evaluation was performed.
A: The initial density value of the image is 1.4 or more.
B: The initial density value of the image is 1.2 or more and less than 1.4.
C: The initial density value of the image is less than 1.2.

[durability]
Following the measurement of the initial density of the image, 8000 images with a printing rate of 1% were output, and then the developing roller was taken out from the electrophotographic process cartridge, and the taken-out developing roller was visually observed. When the resin layer 13 at the end of the developing roller was not cracked or peeled off from the conductive elastic layer 12, it was again incorporated into the electrophotographic process cartridge, the 8000 sheets were output, and the developing roller was visually observed. And durability was evaluated according to the following criteria.
C: Cracking and peeling were observed in the observation after the first 8000 sheets were output.
B: Cracking and peeling were observed in the observation after the second output of 8000 sheets.
A: In the observation after the second output of 8000 sheets, there was no cracking or peeling.

[Surface contamination]
In the durability test, after the first 8000 sheets were output, a solid white image was output, and the fog value was measured, which was used as an index of the surface contamination of the developing roller. The fog value was measured by using a reflection densitometer (manufactured by Tokyo Denshoku Technology Center) to measure the reflection density of the transfer paper before image formation and the output solid white image, and the difference was used as the fog value. As the measurement area, the image print area of the transfer paper was divided into areas of 1 cm × 1 cm in order from the upper left, the fog value in each area was measured, and the maximum value of the value was used as the fog value of the solid white image. The fog is a phenomenon that occurs when the toner adheres to the surface of the developing roller, the charge amount of the toner decreases, and the toner is transferred to the transfer paper. And evaluated according to the following criteria.
A: The fog value is less than 1.0.
B: 1.0 or more and less than 3.0.
C: 3.0 or more and less than 5.0.
D: 5.0 or more.

[Evaluation of deformation amount of developing roller]
The developing roller was incorporated in the electrophotographic process cartridge described above and left in an environment of 40 ° C. and 95% RH for 15 days, and then the electrophotographic process cartridge was left in an environment of 25 ° C. and 45% RH for 24 hours. Thereafter, the electrophotographic process cartridge was mounted on the main body of the electrophotographic image forming apparatus in an environment of 25 ° C. and 45% RH, and a solid black image was output. The resulting solid black image was visually observed for image defects thought to have appeared due to the depression of the developing roller due to contact with the toner regulating member being left, and evaluated according to the following criteria to determine the amount of deformation of the developing roller. It was evaluated.
A: Image defects cannot be confirmed visually.
B: Although image defects can be confirmed slightly by visual observation, there is no practical problem.
C: Image defects can be confirmed visually.
D: Image defects can be clearly confirmed visually.

[Example 2] [Production of developing roller 2]
A developing roller 2 was obtained in the same manner as in Example 1 except that X-2 obtained in Production Example 2 was used as the etherified melamine. Hereinafter, the obtained developing roller 2 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 3] [Preparation of developing roller 3]
A developing roller 3 was obtained in the same manner as in Example 1 except that X-3 obtained in Production Example 3 was used as the etherified melamine. Hereinafter, the obtained developing roller 3 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 4] [Preparation of developing roller 4]
A developing roller 4 was obtained in the same manner as in Example 1 except that X-4 obtained in Production Example 4 was used as the etherified melamine. Hereinafter, the obtained developing roller 4 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 5] [Production of developing roller 5]
A developing roller 5 was obtained in the same manner as in Example 1 except that X-5 obtained in Production Example 5 was used as the etherified melamine. Hereinafter, the obtained developing roller 5 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Examples 6 to 9] [Production of developing rollers 6 to 9]
Developing roller 6 in the same manner as in Example 1 except that the blending amount (solid content) of etherified melamine X-1 was changed to 11.1 parts, 25.0 parts, 100.0 parts, and 150.0 parts, respectively. Thru 9 were obtained. Thereafter, the obtained developing rollers 6 to 9 were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Examples 10 to 13] [Production of developing rollers 10 to 13]
Developing rollers 10 to 13 were obtained in the same manner as in Example 1 except that the solid content concentration was adjusted so that the thickness of the resin layer was 1.0 μm, 2.0 μm, 8.0 μm, and 10.0 μm, respectively. . Hereinafter, as in Example 1, the obtained developing rollers 10 to 13 were evaluated. The results are shown in Table 1.

[Examples 14 to 17] [Production of developing rollers 14 to 17]
Developing rollers 14 to 17 were obtained in the same manner as in Example 1 except that the amount of carbon black was changed to 8 parts, 10 parts, 30 parts, and 33 parts, respectively. Hereinafter, the obtained developing rollers 14 to 17 were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Examples 1 to 4] [Production of Comparative Developing Rollers 1 to 4]
Comparative developing roller 1 in the same manner as in Example 1, except that etherified melamine X-6, etherified melamine X-7, etherified melamine X-8, and etherified melamine X-9 were used as the etherified melamine, respectively. Thru 4 were obtained. Hereinafter, the obtained comparative developing rollers 1 to 4 were evaluated in the same manner as in Example 1. The results are shown in Table 1.

  Table 1 shows the following.

   From the results of Examples 1 to 5, as the etherified melamine resin having the unit represented by the general formula (1), by increasing the number of carbon atoms of the alkyl group represented by R and R ′, the resin layer has an appropriate flexibility. And high chargeability could be achieved, and good images could be obtained. However, it is also suggested that if the number of carbon atoms of the alkyl group represented by R and R ′ is too large, the resin layer becomes too soft and the effect of suppressing deformation becomes small. In addition, when the carbon number of the alkyl group represented by R is too small or R ′ is a hydrogen atom, as seen in Comparative Examples 1 to 4, there is a problem in durability, surface contamination, particularly surface contamination. .

  From the results of Examples 6 to 9, a good image could be obtained by controlling the content of the etherified melamine resin having a unit represented by the general formula (1) in the resin component within an appropriate range. . If the content of the etherified melamine resin is too small, the initial density is slightly lowered because the chargeability is lowered. Also, if the content of etherified melamine resin is too large, the contribution to the increase in the hardness of the resin layer will increase, resulting in a slight decrease in durability and the occurrence of surface contamination (toner adhesion) on the developing roller. Become.

  From the results of Examples 10 to 13, a good image could be obtained by controlling the thickness of the resin layer in an appropriate range. If the thickness of the resin layer is too thin, the durability is reduced due to wear. If the resin layer is too thick, the surface hardness increases, and the surface contamination (toner adhesion) of the developing roller is likely to occur.

  From the results of Examples 14 to 17, a good image could be obtained by controlling the carbon black content in the resin layer within an appropriate range. If the carbon black content is too small, a decrease in the initial concentration is observed due to a decrease in conductivity, and if the carbon black content is too large, the resin layer becomes hard due to the reinforcing effect of the carbon black, resulting in durability. descend.

DESCRIPTION OF SYMBOLS 11 Shaft core 12 Conductive elastic layer 13 Resin layer 201 Developing roller 202 Toner supply roller 203 Toner 204 Toner amount regulating member 205 Developing device 206 Photosensitive drum 207 Cleaning blade 208 Waste toner container 209 Charging member 210 Exposure means 211 Transfer member 212 Recording paper 213 Fixing member 41 Conductive elastic layer 42 Resin layer

Claims (6)

A developing roller comprising a shaft core body and at least one elastic layer around the shaft core body and a resin layer provided on an outer peripheral surface of the elastic layer;
The developing roller, wherein the resin layer includes at least an etherified melamine resin having a unit represented by the general formula (1), resin particles, and carbon black.

(In the formula, R represents an alkyl group having 5 to 8 carbon atoms. R ′ represents an alkyl group having 1 to 3 carbon atoms. * Represents a repeated bond.)   The developing roller according to claim 1, wherein the etherified melamine resin is 20% by mass or more and 50% by mass or less in the resin component of the resin layer.   The developing roller according to claim 1, wherein the resin layer has a thickness of 2 μm or more and 8 μm or less.   The developing roller according to claim 1, wherein a content of the carbon black is 10% by mass or more and 30% by mass or less with respect to the resin component. A rotatable photosensitive drum, a charging member that contacts the photosensitive drum and charges the surface of the photosensitive drum, and a developer roller that contacts the photosensitive drum and supplies the developer to the surface of the photosensitive drum by a developing roller. In an electrophotographic process cartridge having a developing member that develops an image into a developer image,
An electrophotographic process cartridge, wherein the developing roller is the developing roller according to claim 1. A rotatable photosensitive drum, a charging member that contacts the photosensitive drum and charges the surface of the photosensitive drum, an exposure unit that records image information on the surface of the photosensitive drum, and a photosensitive drum that contacts the photosensitive drum A developer member is supplied to the surface of the toner by a developing roller to develop an electrostatic latent image to form a developer image, a transfer member for transferring the developer image to a transfer material, and a development transferred to the transfer material An electrophotographic image forming apparatus comprising: a fixing member that fixes an agent image; and a pressure member that forms a nip portion with the fixing member and conveys the transfer material by pressure contact with the nip portion.
An electrophotographic image forming apparatus, wherein the developing roller is the developing roller according to claim 1.

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