JP2017058615A - Developer carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developer carrier which suppresses chipping of a surface of a developer carrier and can obtain adequate image quality performance even when printing under various environments for a long period of time.SOLUTION: There is provided a developer carrier used in a developing device which visualizes an electrostatic latent image on an electrostatic latent image carrier by developing with a developer carried and conveyed by the developer carrier and has a base and a surface layer on the base, where the surface layer contains a binder resin, conductive fine particles, particles (a) having new Mohs hardness of 10 or more, a number average diameter of less than 2.0 μm and an average circularity of 0.90 or less, and particles (b) having a number average diameter of 2.0 μm or more and a Young's modulus of 100 GPa or more and an average circularity of 0.90 or more, and imparts irregularity to the surface layer, where there exist a plurality of projections derived from the particles (b) on the surface of the surface layer, the particles (b) have the surface covered with the binder resin and are contained in the surface layer in a state of not being exposed on the surface of the surface layer, and the particles (a) are contained in the binder resin which covers the surface of the particles (b) and are contained in the binder resin which exists in a valley portion between the plurality of projections of the surface of the surface layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a developer carrying member that can be suitably used in a developing device provided in an electrophotographic apparatus or the like that visualizes an electrostatic latent image with a developer.

  In recent years, electrophotographic images are required to have high image quality and high durability even when used for a long time in various environments. For that purpose, it is important to maintain a high and uniform charging performance for a long time in the toner as a developer. Further, a developer carrier having a resin layer formed by drying a paint film containing conductive fine particles such as graphite as a surface layer is preferably used.

  Recently, there is known a technique for improving the image quality by controlling the toner on the developer carrying member to a thin layer so that the toner has a high and uniform charge amount. This is a technique for efficiently triboelectrically charging a toner by reducing the amount of toner on the developer carrying member, thereby increasing the number of times of contact between the developer carrying member and the toner. However, in order to make the toner on the developer carrier thin, it is necessary to control and regulate the amount of toner conveyed onto the developer carrier more strongly than in the past. At that time, the amount of toner acting as spacer particles between the developer carrier and the regulating portion is reduced, so that the pressure applied to the surface of the developer carrier increases, and the surface of the developer carrier is scraped over a long period of use. Sometimes happened. Such a phenomenon is likely to occur when used for a long period of time in a high-temperature and high-humidity environment where the fluidity of the toner is reduced and the toner on the developer carrier tends to be a thin layer. In addition, as shown in FIG. 2, in a developing method that regulates the amount of toner transported by bringing an elastic regulating blade into contact with the surface of the developer carrying member, the developer can be used for a long time even in a low temperature environment. The surface of the carrier may be scraped. This is because the elasticity of the regulating blade decreases due to the low temperature environment, and the load on the surface of the developer carrying member increases.

  In order to solve these problems, Patent Document 1 improves the strength by forming a resin layer containing particles having a Mohs hardness of 6 or more on the surface of the developer carrier, and suppresses the development carrier surface from being scraped. doing.

  Further, in Patent Document 2, the surface of the development carrier is improved by forming a resin layer containing particles having a Mohs hardness of 6 or more on the surface of the developer carrier, and by containing high-hardness graphite. Scraping of the is suppressed.

Japanese Patent No. 4280604 Japanese Patent No. 4298471

  When the strength of the surface of the developer carrying member is strengthened as described in Patent Document 1, stress may concentrate on the convex portions existing on the surface of the developer carrying member. When stress is repeatedly concentrated on the convex part by long-term printing, the resin layer of the convex part may be peeled off, and the developability may be deteriorated. Such peeling of the binder resin locally occurs on the surface of the developer carrying member, so that the image quality of a fine image such as a dot image may be deteriorated.

  Also in Patent Document 2, there is no mention of the possibility that the binder resin adhered to the convex portion is peeled off when stress is repeatedly concentrated on the convex portion by long-term printing.

  In the future, in view of the situation where it is required to enable printing for a longer period of time than before, even if printing is performed for a longer period of time in various environments, the surface of the development carrier is suppressed, and At present, there is room for improvement in technology for obtaining stable image performance.

  In view of the above situation, the object of the present invention is to develop that can suppress the surface of the developer carrying member and can obtain good image quality performance from beginning to end even when printing is performed for a long time in various environments. The object is to provide an agent carrier.

According to the present invention,
A developer carrier used in a developing device that develops and visualizes an electrostatic latent image formed on an electrostatic latent image carrier with a developer carried on the developer carrier,
A substrate and a surface layer provided on the substrate;
The surface layer is
Binder resin,
Conductive fine particles,
A new Mohs hardness of 10 or more, a number average diameter of less than 2.0 μm and an average circularity of 0.90 or less, and a number average diameter of 2.0 μm or more, Young's modulus of 100 GPa or more And particles b for imparting irregularities to the surface layer having an average circularity of 0.90 or more
Containing
On the surface of the surface layer, there are a plurality of convex portions derived from the particles b,
In the surface layer, the particle b is coated with the binder resin and is contained in the surface layer in a state of being not exposed to the surface of the surface layer. In addition to being contained in the binder resin covering the surface of the surface layer, it is also contained in the binder resin present in the valleys between the plurality of convex portions on the surface of the surface layer. A developer carrier is provided.

  According to the present invention, there is provided a developer carrier capable of suppressing the abrasion of the surface of the developer carrier and obtaining good image quality performance from beginning to end even when printing is performed for a long time under various environments. Is done.

2 is a cross-sectional view schematically showing a surface layer of a developer carrier in the present invention. FIG. It is a schematic diagram for demonstrating an example of a developing device provided with a developing agent carrier. It is a schematic diagram for demonstrating another example of a developing device provided with a developing agent carrier.

Hereinafter, the present invention will be described in detail.
The present invention relates to a developer carrier used in a developing device that develops an electrostatic latent image formed on an electrostatic latent image carrier with a developer carried on the developer carrier and visualizes the latent image. .

  The developer carrier according to the present invention has a base and a surface layer formed on the base. The surface layer includes a binder resin, conductive fine particles, particles a, and particles b. The particles a are particles having a New Mohs hardness of 10 or more, a number average diameter of less than 2.0 μm, and an average circularity of 0.90 or less. The particles b are particles having a Young's modulus of 100 GPa or more, a number average diameter of 2.0 μm or more, and an average circularity of 0.90 or more. The particle b is a particle for imparting irregularities to the surface layer. A plurality of convex portions derived from the particles b exist on the surface of the surface layer. In the surface layer, the particles b are coated with a binder resin on the surface, and are contained in the surface layer in a state where they are not exposed on the surface of the surface layer. Further, the particle a is included in the binder resin covering the surface of the particle b, and is also included in the binder resin present in the valley portion between the plurality of convex portions on the surface of the surface layer. It is.

  First, the particle a will be described. The particles a are contained for the purpose of improving the durability against abrasion of the surface of the developer carrying member. Therefore, the new Mohs hardness, which is an index of the fragility of the material, that is, the ease of scraping, is 10 or more, preferably 12 or more. The new Mohs hardness is a value determined by a qualitative method in which the talc is 1 and the diamond is 15 and the standard mineral and sample are drawn together and the damage is soft and the hardness is low. . In the present invention, a material having a new Mohs hardness as large as 10 or more, that is, a material that is difficult to scrape is selected for the particles a. Therefore, by including the particles a in the binder resin, the wear resistance of the surface of the developer carrier is improved, and even when printing is performed for a long time, the surface of the developer carrier can be suppressed. When the new Mohs hardness is less than 10, the abrasion resistance of the surface of the developer carrier is not sufficient, so that the surface of the developer carrier due to long-term printing tends to be noticeable.

  Examples of what can be used as the particles a in the present invention include oxides such as aluminum oxide and zirconium oxide; nitrides such as boron nitride, aluminum nitride and titanium nitride; carbides such as silicon carbide, titanium carbide and boron carbide; Examples thereof include borides such as silicon halide and zirconium boride; silicides such as zirconium silicide, and the like. Among these, one kind, or two or more kinds as required can be used.

  The particles a used in the present invention have a number average diameter of less than 2.0 μm, preferably 1.5 μm or less. When the number average diameter of the particles a is less than 2.0 μm, the dispersibility of the particles a in the surface layer of the developer carrying member becomes good, so that sufficient wear resistance can be obtained. As a result, scraping of the surface of the developer carrying member can be suppressed by printing for a long time.

  Further, the particles a of the present invention have an average circularity of 0.90 or less. When the average circularity is 0.90 or less, the particles a can efficiently cover the surface of the developer carrier, so that the wear resistance is improved and the developer carrier surface can be prevented from being scraped.

  By containing the particles a described above, a developer carrying surface excellent in abrasion resistance can be obtained, but it alone suppresses the abrasion of the developer carrying surface even during long-term printing, and has good image quality. A developer carrier having performance cannot be obtained. Simply containing particles a improves the strength against abrasion of the surface of the developer carrying member, but stress concentrates on the protruding portion of the surface of the developer carrying member, so that it adheres to the protruding portion by long-term printing. There is a possibility that the binder resin that had been peeled off. When the binder resin is peeled off, the particles forming the convex portions are exposed on the surface of the developer carrying member, so that the composition on the surface of the developer carrying member is not uniform. As a result, there is a local difference in the charge imparting performance to the toner of the developer carrying member, so that the toner is not uniformly charged, and in particular, a problem that the image quality of a fine image such as a dot image deteriorates easily occurs. .

  In order to obtain a developer carrier having excellent image quality performance while suppressing the abrasion of the developer carrier surface even during long-term printing, even if stress is repeatedly concentrated on the convex portion of the developer carrier surface, It is important that the binder resin covering the part does not peel off. In order to suppress the peeling of the binder resin, it is necessary to appropriately select particles that give the developer carrier surface irregularities.

  As a result of intensive studies by the present inventors, the reason why the binder resin covering the convex portion is peeled off by long-term printing is that stress is concentrated repeatedly on the convex portion, so that the particles inside the convex portion are elastic many times. It was determined that the deformation was caused and the adhesion between the binder resin and the particles was lowered. Therefore, the present inventors focused on the Young's modulus indicating the ease of elastic deformation of the substance, and selected the particles that are difficult to elastically deform, that is, the particles having a large Young's modulus, as the particles that form the protrusions, thereby removing the resin It was found that can be suppressed.

  The particles b used in the present invention are used as convex particles for imparting irregularities to the surface of the developer carrying member, and have a Young's modulus of 100 GPa or more, preferably 200 GPa or more. When the Young's modulus is 100 GPa or more, the elastic deformation of the particles b caused by the stress applied during printing is suppressed, and the adhesion between the particles b and the binder resin can be maintained, so that the binder resin at the convex portion is peeled off. It becomes difficult. As a result, even when printing for a long period of time, the charge imparting performance to the toner of the developer carrier is kept uniform, and fine image quality performance such as a dot image becomes good from beginning to end.

  Examples of what can be used as the particles b include oxides such as aluminum oxide and titanium oxide; metals such as iron, copper, tungsten, titanium and molybdenum; nitrides such as silicon nitride and boron nitride; carbides such as silicon carbide and boron carbide Etc., and one of these can be used, or two or more can be used as necessary.

  Particles b have a number average diameter of 2.0 μm or more. When the thickness is 2.0 μm or more, the size of the irregularities on the surface of the developer carrying member can be easily controlled, and the developer carrying member can have an appropriate toner conveying capability. As a result, even when printing is performed in an environment where the fluidity of the toner is lowered, such as a high-temperature and high-humidity environment, the toner conveyance amount on the developing carrier can be maintained at an appropriate amount, so that a high image density can be obtained.

  Further, the particles b have an average circularity of 0.90 or more. If the spherical particles have an average circularity of 0.90 or more, the difference between the long side and the short side of the particles b is small, so that the surface of the developer carrying member can be provided with uniform irregularities and development with stable toner transport performance. An agent carrier can be obtained. As a result, when printing is performed in an environment where the fluidity of the toner is lowered, such as a high temperature and high humidity environment, the amount of toner transported on the developing carrier becomes an appropriate amount, and a high image density can be obtained.

  Further, as shown in FIG. 1, in the surface layer of the developer carrier, the surface of the particle b (2) is coated with the binder resin (4) and is not exposed on the surface of the surface layer. It is contained in. In addition, the particles a (1) are contained in the binder resin covering the surface of the particles b, and in the binder resin present in the valleys between the plurality of convex portions on the surface of the surface layer. It is important that it is also included. When the particles b are exposed on the surface of the developer carrying member, the composition of the surface of the developer carrying member becomes non-uniform, so that a local difference occurs in the charge imparting performance to the toner of the developer carrying member. As a result, the charge-carrying performance to the toner of the developing carrier is not uniform, and a problem that the image quality of a fine image such as a dot image is deteriorated easily occurs.

  In order not to expose the surface of the particle b with the binder resin and expose it to the surface of the developer carrying member, the number average diameter of the particle b is preferably 5 times or more than the number average diameter of the particle a. When the ratio of the particle size of the particle b to the particle a (particle b diameter / particle a diameter) is 5 or more, the binder resin layer containing the particles a easily includes the particles b. Exposure to the surface of the agent carrier can be prevented.

  Further, it is desirable that the particles a are uniformly dispersed throughout the surface regardless of the concave and convex portions on the surface of the developer carrying member. Since the particles a are uniformly present, the wear resistance of the surface of the developer carrying member becomes uniform, so that partial abrasion can be suppressed. As a result, a phenomenon that the image quality of a fine image such as a dot image is deteriorated hardly occurs.

  Next, as the binder resin used in the present invention, generally known resins, in particular, resins known in the field of developer carriers can be used.

  For example, phenol resin, epoxy resin, polyamide resin, polyester resin, polycarbonate resin, polyolefin resin, silicone resin, fluorine resin, styrene resin, vinyl resin, cellulose resin, melamine resin, Examples include urea resins, polyurethane resins, polyimide resins, and acrylic resins. Considering the mechanical strength, a heat or photo-curing resin is more preferable, but a thermoplastic resin can also be applied as long as it has sufficient mechanical strength.

  The surface roughness of the surface layer of the developer carrying member is preferably in the range of 0.30 μm or more and 2.50 μm or less in arithmetic average roughness (Ra) defined in JIS B0601-2001. If the thickness is 0.30 μm or more, it is easy to sufficiently transport the developer, and it is easy to suppress the occurrence of image defects due to image density thinning due to lack of toner and uneven toner coating. Moreover, if it is 2.50 μm or less, it is easy to make the toner imparted with frictional charge easily, so that it is possible to easily suppress the occurrence of thin image density due to insufficient frictional charging.

  The film thickness of the surface layer is preferably in the range of 5.0 μm or more and 30.0 μm or less, although the preferred film thickness varies depending on the development method and the number average diameter of the particles b. If the film thickness is 5.0 μm or more, the surface layer can easily cover the entire surface of the substrate without any gaps, so that the substrate is not partially exposed, and the developer can be uniformly charged with friction. It becomes easy. In addition, when the film thickness is 30.0 μm or less, it is easy to stably control the surface roughness. Further, it is preferable that the film thickness is larger than the value of the number average diameter of the particles b from the viewpoint that the particles b are easily included.

  As a method for obtaining the surface layer of the developer carrying member according to the present invention, it is preferable to disperse and mix the components forming the surface layer in a solvent to form a paint and apply it onto the substrate of the developer carrying member. For dispersing and mixing each component, a known media dispersing device such as a ball mill, a sand mill, an attritor, or a bead mill, or a known medialess dispersing device using a collision type atomization method or a thin film swirling method can be suitably used. is there. As a coating method for the dispersed paint, known methods such as a dipping method, a spray method, a roll coating method, and an electrostatic coating method can be applied.

  The developer carrier according to the present invention contains conductive fine particles in the surface layer. As the conductive fine particles used in this case, a known material can be appropriately selected in the field of the developer carrier, and examples thereof include the following. Fine powders of metals such as aluminum, copper, nickel and silver; conductive metal oxides such as antimony oxide, indium oxide, tin oxide, titanium oxide, zinc oxide, molybdenum oxide and potassium titanate; crystalline graphite; various carbon fibers Conductive carbon black such as furnace black, lamp black, thermal black, acetylene black, channel black; metal fiber. These may be used simultaneously.

  The conductive fine particles can be appropriately selected in order to make the volume resistivity of the surface layer a desired value. Among these, carbon black and graphite are particularly preferable because they are excellent in dispersibility and electrical conductivity.

  Of these, conductive carbon black, especially conductive amorphous carbon, is particularly excellent in electrical conductivity. It can be filled to a certain degree of conductivity by simply filling the polymer material with conductivity and controlling the amount added. Can be suitably used. In addition, the dispersion stability and coating stability are also improved due to the thixotropic effect of the paint.

  In addition to being excellent in electrical conductivity, crystalline graphite increases surface lubricity by adding it to the surface layer and improves toner contamination resistance of the surface layer.

  Although the addition amount of electroconductive fine particles changes also with the particle sizes, it is preferable to set it as the range of 1 to 100 mass parts with respect to 100 mass parts of binder resin. If it is 1 part by mass or more, it becomes possible to reduce the resistance and high lubricity of the resin layer, and if it is 100 parts by mass or less, the resistance (resistance to wear) of the surface layer is not greatly reduced. The value can be suitably reduced.

  In addition, the volume average particle diameter of the conductive particles is preferably 10 nm or more from the viewpoint of dispersion stability and 20 μm or less from the viewpoint of resistance uniformity of the resin composition.

The volume resistance value of the surface layer formed on the developer carrier of the present invention is preferably 1 × 10 ⁻¹ Ω · cm or more and 1 × 10 ⁵ Ω · cm or less, preferably 1 × 10 ⁻¹ Ω. More preferably, it is cm or more and 1 × 10 ³ Ω · cm or less. When the volume resistance value is 1 × 10 ⁻¹ Ω · cm or more and 1 × 10 ⁵ Ω · cm or less, it is easy to appropriately charge the developer.

  Next, an example of a developing device that realizes a developing method using the developer carrying member of the present invention will be specifically described with reference to the drawings. FIG. 2 shows a schematic diagram of an example of a developing device for realizing a developing method using the developer carrying member of the present invention. However, in the present invention, as the substrate, the arrangement of the surface layer on the substrate, and the shape of the developer carrier, a known form as the developer carrier can be appropriately employed.

  When developing using the developer carrying member of the present invention, as shown in FIG. 2, an elastic regulating blade is used, and this elastic regulating blade 616 is brought into contact with or pressed against the developing sleeve via the developer. It is preferable to use the system used. In FIG. 2, an electrostatic latent image carrier, for example, a photosensitive drum 601 that carries an electrostatic latent image formed by a known process, rotates in the direction of arrow B. The developing sleeve 608 carries a one-component magnetic developer having magnetic toner particles supplied to the developing container 603 and rotates in the direction of arrow A so that the developing sleeve 608 and the photosensitive drum 601 face each other. The developer is transported to the development area D. As shown in FIG. 2, in the developer carrier 610 held rotatably, a magnet (magnet roller) is provided in the developing sleeve 608 to magnetically attract and hold the developer on the developing sleeve 608. 609 is arranged. The developing sleeve 608 has a resin layer (surface layer) 607 coated on a metal cylindrical tube 606 as a base. A developing bias voltage is applied to the developing sleeve by a power source 613. The developing container is divided into a first chamber 614 and a second chamber 615, and the magnetic developer existing in the first chamber 614 passes through a gap formed by the developing container 603 and the partition member 604 by the stirring and conveying member 605. And sent to the second chamber 615. The magnetic developer is carried on the developing sleeve 608 by the action of magnetic force by the magnet roller 609. A stirring member 611 is provided in the second chamber 615 to prevent the developer from staying. The developer obtains a triboelectric charge capable of developing the electrostatic latent image on the photosensitive drum 601 by friction between the magnetic toners and the resin layer 607 on the developing sleeve 608. In FIG. 2, an elastic regulating blade made of an elastic member is used as the developer layer thickness regulating member 616 that regulates the layer thickness of the developer on the developing sleeve 608. Examples of the elastic regulating blade made of an elastic member include those made of an elastic plate made of a material having rubber elasticity such as urethane rubber or silicone rubber, or a material having metal elasticity such as phosphor bronze or stainless steel. The elastic regulating blade 616 may be used in contact with or pressed against the developing sleeve 608 via toner. In the present invention, particularly in a system having this form, a remarkable effect can be obtained in terms of triboelectric charge imparting ability. Can be obtained.

  This is due to the following reason. In a developing device that contacts or presses an elastic regulating blade, a thin layer of developer can be formed on the developing sleeve 608 while the toner coat layer is subjected to strong regulation. The contact pressure of the elastic regulating blade 616 against the developing sleeve 608 is preferably a linear pressure of 5 g / cm or more and 50 g / cm or less (4.9 N / m or more and 49 N / m or less). When the contact pressure is within the above range, it is easy to stabilize the regulation of the developer and optimize the amount of developer and the amount of triboelectric charge carried on the developer carrying member. Further, the regulation of the developer becomes weak, and it is possible to easily prevent a phenomenon such as fogging or developer leakage. In addition, it is possible to suppress damage to the toner and easily prevent phenomena such as developer deterioration and fusion to the sleeve and the elastic regulation blade.

  FIG. 2 shows an example in which an elastic regulating blade is used as a developer layer thickness regulating member that regulates the layer thickness of the developer on the developing sleeve 608. The elastic regulation blade can be made of an elastic plate made of a material having rubber elasticity such as urethane rubber or silicone rubber, or a material having metal elasticity such as phosphor bronze or stainless steel. However, in place of the elastic regulating blade, as shown in FIG. 3, a magnetic blade 602 disposed away from the developing sleeve may be used. FIG. 3 shows a developer supply member (such as a screw) 612, which is a member for supplying developer (toner) into the developer container 603 from a developer supply container (not shown).

  2 and 3 schematically illustrate a developing device that can use the developer carrying member of the present invention. In addition to the layer thickness regulating member described above, there are various forms such as the shape of the developing container 603 (hopper), the presence / absence of the stirring blades 605 and 611, the arrangement of the magnetic poles, the shape of the supply member 612, and the presence / absence of the supply container. Needless to say.

  Next, a method for measuring physical properties according to the present invention will be described. The following measurement methods were employed in the examples.

(1) Measurement of number average diameter of particle a and particle b The number average diameter of particle a and particle b is observed and measured by “Scanning Electron Microscope S-4800” (trade name, manufactured by Hitachi High-Technologies Corporation). did. The number average diameter of each particle was measured by measuring the length of two horizontal and vertical sides of 300 particles from an electron micrograph, and calculating the average of the lengths of the two sides (arithmetic average of 600 total lengths). Calculated as

  When obtaining the number average particle diameter of the particles present in the developer carrier surface layer, the cross section of the developer carrier surface layer is cut out, and the lengths of two vertical and horizontal sides of 300 particles present in the cross section are determined. It can be measured and obtained from the average of the lengths of the two sides.

(2) Measurement of the arithmetic average roughness (Ra) of the developer carrier surface The measurement of the arithmetic average roughness (Ra) of the developer carrier surface is based on the surface roughness of JIS-B0601 (2001). A roughness measuring device “SURFCOM 1500DX” (trade name, manufactured by Tokyo Seimitsu Co., Ltd.) was used. The measurement conditions were a cutoff of 0.8 mm, an evaluation length of 8 mm, and a feed rate of 0.6 mm / s. The measurement positions are a total of three positions, the middle position between the developer carrier and the both ends of the coating. Further, after rotating the 90 ° developer carrier, the same three locations, and further 90 ° developer carrier. After the rotation, the measurement was similarly performed at three points, a total of nine points, and the average value was taken.

(3) Measurement of average circularity of particle a and particle b The average circularity of particle a and particle b is measured and analyzed during calibration by a flow particle image analyzer “FPIA-3000” (manufactured by Sysmex Corporation). Measured under conditions.

  A specific measurement method is as follows. First, about 20 ml of ion-exchanged water from which impure solids are removed in advance is put in a glass container. About 0.2 ml of a diluted solution obtained by diluting “Contaminone N” (trade name, manufactured by Wako Pure Chemical Industries, Ltd.) with ion-exchanged water about 3 times by mass as a dispersant is added thereto. Contaminone N is a 10% by weight aqueous solution of a neutral detergent for pH 7 precision measuring instrument cleaning comprising a nonionic surfactant, an anionic surfactant and an organic builder. Further, about 0.02 g of a measurement sample is added, and dispersion treatment is performed for 2 minutes using an ultrasonic disperser to obtain a dispersion for measurement. At that time, the dispersion is appropriately cooled so that the temperature of the dispersion becomes 10 ° C. to 40 ° C. As the ultrasonic disperser, a desktop ultrasonic cleaner disperser (for example, trade name: “VS-150” (manufactured by Vervo Creer)) having an oscillation frequency of 50 kHz and an electric output of 150 W is used. A predetermined amount of ion-exchanged water is placed in the water tank of the ultrasonic cleaner / disperser, and about 2 ml of the contamination N is added to the water tank.

  For the measurement, the flow type particle image analyzer equipped with “LUCPLFLN” (trade name, manufactured by Olympus, magnification 20 ×, numerical aperture 0.40) as an objective lens is used, and the particle sheath “PSE-900A” is used as the sheath liquid. (Trade name, manufactured by Sysmex Corporation). The dispersion prepared in accordance with the above procedure is introduced into the flow type particle image analyzer, and 2000 toners are measured in the HPF measurement mode and in the total count mode. Then, the binarization threshold at the time of particle analysis was set to 85%, the analysis particle diameter was limited to a circle equivalent diameter of 1.977 μm or more and less than 39.54 μm, and the average circularity of the measurement sample was obtained.

  In measurement, automatic focus adjustment is performed using standard latex particles before the measurement is started. Thereafter, it is preferable to perform focus adjustment every two hours from the start of measurement. As the standard latex particles, for example, “RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5100A” manufactured by Duke Scientific is diluted with ion-exchanged water and used.

  In the examples of the present application, a flow-type particle image analyzer that has been issued a calibration certificate issued by Sysmex Corporation, which has been calibrated by Sysmex Corporation, was used. The measurement was performed under the measurement and analysis conditions when the calibration certificate was received, except that the analysis particle diameter was limited to a circle equivalent diameter of 1.977 μm or more and less than 39.54 μm.

  The particles present on the surface layer of the developer carrying member were extracted by dissolving the surface layer with N-methylpyrrolidone heated to about 200 ° C.

(4) Measurement of Young's modulus of particle b The Young's modulus of particle b was measured based on the JIS standard for elastic modulus measurement. For metal materials, measurement was performed based on JIS Z 2280 (Young's modulus of metal materials), and for oxides based on JIS R 1602 (elastic constant at room temperature of ceramics).

(5) Volume resistance measurement of surface layer (resin layer) of developer carrier The same coating as the coating liquid for forming the surface layer on developer carrier on a polyethylene terephthalate (PET) sheet having a thickness of 100 μm A 20 μm resin layer was formed using the solution, and the volume resistance value was measured with a resistivity meter Loresta AP (trade name, manufactured by Mitsubishi Chemical Corporation) using a 4-terminal probe. The measurement environment was a temperature of 20 ° C. or more and 25 ° C. or less, a humidity of 50% RH (relative humidity) or more and 60% RH or less.

(6) Measurement of film thickness and scraping amount of developer carrier surface layer External diameter of developer carrier before and after surface layer formation by laser length measuring device (manufactured by KEYENCE, trade name: controller LS-5500, sensor head LS5040T) Was measured. From the measured values before and after that, the average value of 30 points was taken to calculate the film thickness (μm) of the developer carrier surface layer. The amount of scraping of the developer carrier surface layer was measured by measuring the outer diameter of the developer carrier before and after the endurance using the same device, and taking the average value of 30 points from the measured values before and after that. The scraping amount (μm) of the body surface layer was calculated.

(7) Measurement of weight average particle diameter (D4) of toner 0.1 to 5 ml of a surfactant (alkylbenzene sulfonate) is added to 100 ml or more and 150 ml or less of an electrolyte solution, and 2 to 20 mg of a measurement sample is added thereto. . The electrolytic solution in which the sample was suspended was dispersed for 1 to 3 minutes with an ultrasonic disperser, and a particle size distribution of 0.3 to 40 μm was measured with a Coulter counter multisizer using a 100 μm aperture as a reference. The measurement data measured under these conditions was analyzed with the dedicated software attached to the apparatus, and the weight average particle diameter (D4) was calculated.

(8) Observation of Covering State of Particles b The covering state of the particles b can be observed with “Scanning Electron Microscope S-4800” (trade name, manufactured by Hitachi High-Technologies Corporation). 100 points on the surface of the developer carrying member are observed to confirm whether the particle b is covered with the surface layer (binder resin), and the case where 80 points or more are covered is defined as being covered. .

(9) Observation of presence state of particle a The presence state of the particle a is obtained by cutting the developer carrier and cutting the cut surface with a “scanning electron microscope S-4800” (trade name, manufactured by Hitachi High-Technologies Corporation). This was confirmed by observation.

  Although the basic configuration and features of the present invention have been described above, the present invention will be specifically described below based on examples. However, the present invention is not limited to this. In addition, unless otherwise indicated, the part and% in the following mixing | blending show a mass part and mass%, respectively.

<Particle a>
Table 1 shows the particles a used in Examples and Comparative Examples. Each particle obtained a desired number average diameter using a sieve or a classifier if necessary.

<Particle b>
Table 2 shows the particles b used in the examples and comparative examples. Each particle obtained a desired number average diameter using a sieve or a classifier if necessary.

<Conductive fine particles 1>
As the conductive fine particles 1, Toka Black # 5500 (trade name, manufactured by Tokai Carbon Co., Ltd.) was used.

<Conductive fine particles 2>
Using a mixture of coke and tar pitch, this mixture was kneaded at a temperature equal to or higher than the softening point of tar pitch, extruded, and subjected to primary firing at 1000 ° C. in a nitrogen atmosphere to be carbonized. Subsequently, after impregnating with coal tar pitch, secondary firing was performed at 2800 ° C. in a nitrogen atmosphere, and further pulverization and classification were performed to obtain conductive fine particles 2 having a number average diameter of 2.9 μm.

  Next, the developer carrier used in the examples and comparative examples will be described.

<Preparation of developer carrier 1>
Methanol was added to the following materials to adjust the solid content to 40%, and this was dispersed in a sand mill (using glass beads having a diameter of 1 mm as media particles) for 2 hours.
-Binder resin: J325CA (trade name, manufactured by DIC Corporation): 100 parts-Conductive fine particles 1: 60 parts-Conductive fine particles 2: 6 parts-Particle a: a-1: 20 parts-Particle b: b-1 : 10 parts.

  After separating the glass beads using a sieve, methanol was added so that the solid content concentration was 30% to obtain a coating material for the developer carrier 1.

  The obtained coating material was spray-coated on a substrate to obtain a developer carrier 1. Specifically, a cylindrical aluminum tube having an outer diameter of 20.0 mmφ (diameter) and an arithmetic average roughness Ra of 0.2 μm with masking on the upper and lower ends was prepared as a base. The substrate was erected vertically and rotated at a constant speed, and the paint 1 was applied while lowering the spray gun at a constant speed. Subsequently, the coating layer was dried and cured by heating at 190 ° C. for 30 minutes in a hot air drying oven to form a resin layer on the substrate, thereby producing a developer carrier 1. The volume resistance, arithmetic average roughness Ra, and film thickness of the surface layer of the developer carrier 1 were measured and found to be 0.5888 Ω · cm, 1.35 μm, and 15.7 μm, respectively.

  Further, it was confirmed that the surface of the particle b was covered with a binder resin and contained in the surface layer in an unexposed state on the surface of the surface layer. Further, the particles a are included in the binder resin covering the surface of the particles b, and also included in the binder resin present in the valleys between the plurality of convex portions on the surface of the surface layer. Confirmed.

<Preparation of developer carriers 2-11 and 16-23>
The developer carrier 2 is the same as the developer carrier 1 except that the types and addition amounts of the particles a and b and the addition amount of the binder resin and conductive fine particles are changed from the developer carrier 1. -11 and 16-23 were produced. Table 3 shows the formulation and physical properties of each developer carrier.

<Preparation of Developer Carriers 12-15 and 25-27>
The same as the developer carrier 1 except that the base is changed to an aluminum cylindrical tube having an outer diameter of 24.5 mmφ, and the types and addition amounts of the particles a and b and the addition amount of the binder resin and conductive fine particles are changed. In this manner, developer carriers 12 to 15 and 25 to 27 were prepared. Table 3 shows the formulation and physical properties of each developer carrier.

  When the presence state of the particles a and the particles b was confirmed, the developer carrying member 24 was in a state where the particles b were exposed. This is because the particle size of the particle b is larger than the film thickness of the surface layer. It was confirmed that the other developer-carrying members were covered with the binder resin and contained in the surface layer in a state where the particles b were not exposed on the surface layer. In addition, for the developer carrier to which the particles a are added, the presence state of the particles a is observed and contained in the binder resin covering the surface of the particles b, and a plurality of surfaces on the surface of the surface layer are included. It was confirmed that it was also included in the binder resin present in the valleys between the convex portions.

  The toner as the developer was produced as follows.

<Example of toner production>
Styrene-acrylic resin: 100 parts by mass Magnetite: 90 parts by mass Hydrocarbon wax (melting point 105 ° C.): 2 parts by mass Charge control agent (azo type iron complex): 2 parts by mass.

  The above materials were premixed with a Henschel mixer and then melt kneaded with a biaxial kneading extruder. The obtained kneaded product is cooled, coarsely pulverized with a hammer mill, then pulverized with a jet mill, and the resulting finely pulverized powder is classified using a multi-division classifier utilizing the Coanda effect to obtain a weight average particle size ( D4) 6.8 μm negative triboelectrically chargeable toner particles were obtained. As a fluidity-imparting agent, 1.0 part by mass of hydrophobic silica fine powder and 3.0 parts by mass of strontium titanate were externally added and mixed, and sieved with a mesh having a mesh size of 150 μm to obtain a toner.

Example 1
Using developer carrier 1, it was incorporated into a Canon copier (trade name: image RUNNER ADVANCE 2320) having the configuration shown in FIG. 1 and modified so that the process speed was 230 mm / sec and evaluated. It was. The copying environment varied depending on the evaluation, and was performed in a high temperature and high humidity (H / H) environment (30 ° C., 85% RH) and a low temperature and low humidity (L / L) environment (15 ° C., 10% RH).

In each of the above environments, image evaluation was performed initially and after printing 200,000 sheets (durability) in a two-sheet intermittent mode using a text chart with a printing ratio of 1%. The method of each evaluation test will be described in detail later, but is summarized as follows.
Evaluation 1: Before and after endurance in the H / H environment (1% text chart, 200,000 sheets, 2 sheets intermittent), the image density of the solid circle was evaluated by copying in the H / H environment (5.5% test chart).
Evaluation 2: The amount of abrasion on the surface of the developer carrying member was evaluated after endurance in the L / L environment.
Evaluation 3: Before and after endurance in the H / H environment, 10 5% FFH images were printed in the H / H environment, and then the dot FFH images were printed in the H / H environment to evaluate the roughness index.
That is, in evaluations 1 and 3, all printing including durability was performed in the H / H environment, and in evaluation 2, all printing including durability was performed in the L / L environment.

<1> Image Density Copy image density of a 5 mm solid round part on a copy obtained by outputting a test chart with an image ratio of 5.5% is reflected by a reflection densitometer “RD918” (trade name, manufactured by Macbeth). The reflection density was measured, and the average value of the 10 points was used as the image density, and evaluation was performed according to the following criteria.

The copying environment varied depending on the evaluation, and was performed in an environment of high temperature and high humidity H / H (30 ° C., 85% RH).
Rank A (very good): Image density 1.40 or more Rank B (good): Image density 1.35 or more and less than 1.40 Rank C (normal): Image density 1.25 or more and less than 1.35 Rank D (practical lower limit) ): Image density of 1.20 or more and less than 1.25 Rank E (unusable): Image density of less than 1.20.

<2> Abrasion amount on the surface of the developer carrier The amount of abrasion on the surface of the developer carrier was evaluated in a printing environment of a low temperature and low humidity environment L / L (15 ° C., 10% RH). The amount of scraping after initial and after durability was evaluated according to the following criteria.
Rank A (very good): Shave amount less than 2.0 μm Rank B (good): Shave amount from 2.0 μm to less than 4.0 μm Rank C (normal): Shave amount from 4.0 μm to less than 6.0 μm Rank D (practical lower limit) ): Abrasion amount 6.0 μm or more and less than 8.0 μm Rank E (unusable): Abrasion amount 8.0 μm or more.

<3> Image quality evaluation of dot images GN1
Ten FFH images with an image ratio of 5% were printed in an environment of high temperature and high humidity H / H (30 ° C., 85% RH). Thereafter, a dot image (FFH image) in which one pixel is formed by one dot was created. The spot diameter of the laser beam was adjusted so that the area per dot on the paper was 20000 μm ² or more and 25000 μm ² or less. The area of 1000 dots was measured using a digital microscope VHX-500 (trade name: lens wide range zoom lens VH-Z100, manufactured by Keyence Corporation). The number average (S) of dot areas and the standard deviation (σ) of dot areas were calculated, the roughness index was calculated according to the following formula, and evaluated according to the following evaluation criteria.

Gastling index (I) = σ / S × 100
(Evaluation criteria)
A (very good): I is less than 1.0 B (good): I is 1.0 or more and less than 2.0 C (normal): I is 2.0 or more and less than 3.0 D (practical lower limit): I Is 3.0 or more and less than 4.0 E (unusable): I is 4.0 or more.

The FFH image is a value in which 256 gradations are displayed in hexadecimal. 00H is the first gradation (white background part), and FFH is the 256th gradation (solid part).
The test results of Example 1 are shown in Table 4. In Table 4, the result of the evaluation 1 (image density) is a column indicated as “durability H / H”, and the evaluation 2 (the amount of abrasion on the surface of the developer carrying member) is indicated as a column indicated as “scrap L / L”. The result of evaluation 3 (dot image quality evaluation GN1) is shown in the column labeled “GN1”.

(Examples 2 to 11 and Comparative Examples 1 to 9)
The developer carrying member used for evaluation was changed as shown in Table 4, and evaluations of Examples 2 to 11 and Comparative Examples 1 to 9 were performed in the same manner as in Example 1. The test results are shown in Table 4.

(Examples 12 to 15 and Comparative Examples 10 to 12)
The equipment used for the evaluation was changed to a Canon copier (product name: image RUNNER ADVANCE 6275) having the configuration shown in FIG. 3, and the process speed was changed to 400 mm / sec to evaluate the image (durability). Was changed to 2 million. Further, the developer carrier used for evaluation was changed as shown in Table 4. Otherwise, the evaluations of Examples 12 to 15 and Comparative Examples 10 to 12 were performed in the same manner as the evaluation performed in Example 1. The evaluation results are shown in Table 4.

1 Particle a
2 particles b
3 Conductive fine particles 4 Binder resin

Claims (2)

A developer carrier used in a developing device that develops and visualizes an electrostatic latent image formed on an electrostatic latent image carrier with a developer carried on the developer carrier,
A substrate and a surface layer provided on the substrate;
The surface layer is
Binder resin,
Conductive fine particles,
A new Mohs hardness of 10 or more, a number average diameter of less than 2.0 μm and an average circularity of 0.90 or less, and a number average diameter of 2.0 μm or more, Young's modulus of 100 GPa or more And particles b for imparting irregularities to the surface layer having an average circularity of 0.90 or more
Including
On the surface of the surface layer, there are a plurality of convex portions derived from the particles b,
In the surface layer, the particle b is coated with the binder resin and is contained in the surface layer in a state of being not exposed to the surface of the surface layer. In addition to being contained in the binder resin covering the surface of the surface layer, it is also contained in the binder resin present in the valleys between the plurality of convex portions on the surface of the surface layer. A developer carrier.   The developer carrying member according to claim 1, wherein the number average diameter of the particles b is 5 times or more than the number average diameter of the particles a.

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