JP2008241815A - Developing cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing cartridge having a developing roller constituted by forming a resin layer having conductivity on the outer periphery of a conductive shaft and a regulating blade, which prevents the resin layer from being peeled, continuously yields a high-density toner image with little density fluctuation and does not cause in-machine soiling (toner overflow) even when performing print of many sheets by filling the developing cartridge with non-magnetic one-component developer. <P>SOLUTION: In the developing cartridge 20 having the developing roller 25 produced by forming the resin layer having conductivity on the outer periphery of the conductive shaft, the non-magnetic one-component developer and the regulating blade 28, the material of the regulating blade 28 is a phosphor bronze plate, and the regulating blade 28 abuts on the developing roller 25 with average abutting pressure of 10 to 50 N/m. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing cartridge.

  Currently, color image forming apparatuses (for example, printers and copiers) are required to be small, light, and low in cost.

  In order to satisfy the above requirements, it is necessary to reduce the size, weight, and cost of the developing cartridge by reducing the size, weight, and cost of the four developing rollers used in the color image forming apparatus.

  As a developing cartridge for a non-magnetic one-component developer, a developing cartridge using a developing roller and a regulating blade is disclosed (for example, see Patent Document 1).

  As the developing roller used in the developing cartridge, a structure in which a resin layer is provided on a rubber shaft provided on the outer periphery of a metal shaft is used. Since this developing roller has a multilayer structure comprising a rubber-like elastic layer having a thickness of about 5 mm and a resin layer having a thickness of about 1 mm, it is difficult to reduce the size and the cost is high. The current situation accounts for half.

In order to reduce the size and cost of the developing roller, a configuration in which a resin layer is simply formed on the outer periphery of the metal shaft from a multilayer structure in which a rubber-like elastic layer is provided on the outer periphery of the metal shaft. It is advantageous to change to a developing roller.
JP-A-6-236107

  However, the developing roller with a resin layer formed on the outer periphery of the metal shaft without a rubber-like elastic layer relaxes the contacted stress when it comes into contact with the regulating blade to charge the non-magnetic one-component developer. However, there is a problem that the regulation blade vibrates and the non-magnetic one-component developer cannot be charged stably.

  Further, if the contact pressure is increased in order to prevent vibration of the regulating blade, the resin layer of the developing roller may be peeled off.

  The present invention applies a non-magnetic one-component developer (hereinafter also referred to as non-magnetic one-component toner or simply toner) to a developing cartridge having a developing roller having a conductive resin layer formed on the outer periphery of a conductive shaft and a regulating blade. Providing a developer cartridge that does not cause peeling of the resin layer even when loaded and prints many sheets, and can continuously obtain a high-density toner image with little fluctuation in density, and does not cause internal contamination (toner spillage). The purpose is to do.

  The present invention is achieved by adopting the following configuration.

1. In a developing roller having a conductive roller formed on the outer periphery of a conductive shaft, a non-magnetic one-component developer, and a developing cartridge having a regulating blade,
The material of the regulation blade is a phosphor bronze plate,
A developing cartridge, wherein the regulating blade is in contact with the developing roller at a contact pressure average of 10 to 50 N / m.

  The developing cartridge of the present invention does not peel off the resin layer of the developing roller even after printing a large number of sheets, and continuously obtains a toner image with high density and little density fluctuation, and does not cause in-machine contamination (toner spillage). Has an excellent effect.

  In order to reduce the size and reduce the cost of the developing roller, the present inventors used a developing roller having a conductive resin layer formed on the outer periphery of a conductive shaft and printed a large number of sheets with a non-magnetic one-component developer. However, the development of the developing cartridge was examined in which the resin layer on the surface of the developing roller does not peel off, a toner image having a high density and a small density fluctuation can be continuously obtained, and in-machine contamination (toner spillage) does not occur. .

  As a result of investigation, the material of the regulating blade that contacts the developing roller with the conductive resin layer formed on the outer periphery of the conductive shaft is specified, and the contact pressure average that the regulating blade contacts the developing roller is set to a specific value As a result, even when a large number of sheets are printed using a non-magnetic one-component developer, the resin layer on the surface of the developing roller does not peel off, and a high-density toner image with little density fluctuation can be continuously obtained. A developing cartridge in which dirt (toner spillage) does not occur can be provided.

  The developing cartridge of the present invention uses a developing roller having a conductive resin layer formed on the outer periphery of a conductive shaft, uses phosphor bronze as the material of the regulating blade, and calculates the contact pressure average of the regulating blade that contacts the developing roller. It is characterized by being 10 to 50 N / m.

  By using a developing roller in which a conductive resin layer is formed on the outer periphery of the conductive shaft, it is possible to reduce the size and cost of the developing roller.

  It is also presumed that by using phosphor bronze for the regulating blade, the charging sequence of the regulating blade is more positive than that of stainless steel, so that negatively charged non-magnetic one-component toner can be charged more stably.

  In addition, by setting the contact pressure average to 10 N / m or more, the non-magnetic one-component toner can be uniformly charged, and the toner having a low charge amount can be prevented from scattering from the surface of the developing roll, and excessive. In addition, it is possible to prevent the non-magnetic one-component toner from being conveyed to the developing unit. By making the contact pressure average 50 N / m or less, non-magnetic one-component toner can be uniformly charged without damaging the resin layer of the developing roller, and non-magnetic one-component toner is required for the developing portion. Can be transported in quantity.

  Hereinafter, the present invention will be described in detail.

<Development cartridge>
The cartridge of the present invention has at least a developing roller and a regulating blade, and is used as a developing device for non-magnetic one-component toner.

  FIG. 1 is a schematic sectional view showing an example of the developing cartridge of the present invention.

  The developing cartridge 20 shown in FIG. 1 has a buffer chamber 26 adjacent to the developing roller 25, and a hopper 27 and the like adjacent to the buffer chamber 26.

  In the buffer chamber 26, a regulating blade 28, which is a toner regulating member, is disposed in a state of being pressed (contacted) with the developing roller 25. The regulating blade 28 regulates the charge amount and adhesion amount (conveyance amount) of the toner on the developing roller 25. Further, an auxiliary blade 29 for assisting in regulating the toner charge amount and the adhesion amount on the developing roller 25 may be further provided on the downstream side of the regulating blade 28 with respect to the rotation direction of the developing roller 25.

  A supply roller 30 is pressed against the developing roller 25. The supply roller 30 is driven to rotate in the same direction as the developing roller 25 (counterclockwise direction in the drawing) by a motor (not shown). The supply roller 30 has a conductive cylindrical base and a foam layer formed of urethane foam or the like on the outer periphery of the base.

  The hopper 27 contains toner T which is a non-magnetic one-component developer. The hopper 27 is provided with a rotating body 31 for stirring the toner T. A film-like conveying blade is attached to the rotating body 31, and the toner T is conveyed by the rotation of the rotating body 31 in the arrow direction. The toner T conveyed by the conveying blades is supplied to the buffer chamber 26 via a passage 32 provided in a partition wall that separates the hopper 27 and the buffer chamber 26. The shape of the conveying blade is bent while conveying the toner T in front of the rotating direction of the blade as the rotating body 31 rotates, and returns to a straight state when the left end of the passage 32 is reached. Thus, the toner T is supplied to the passage 32 by returning the shape of the blade straightly through the curved state.

  The passage 32 is provided with a valve 321 for closing the passage 32. This valve is a film-like member, and one end is fixed to the upper side of the right side of the passage 32 of the partition wall. When the toner T is supplied from the hopper 27 to the passage 28, the valve 32 is pushed rightward by the pressing force from the toner T. Can be opened. As a result, the toner T is supplied into the buffer chamber 26.

  In the developing cartridge 20, the developing roller 25 is rotationally driven in the direction of the arrow during image formation, and the toner in the buffer chamber 26 is supplied onto the developing roller 25 by the rotation of the supply roller 30. The toner T supplied onto the developing roller 25 is charged and thinned by the regulating blade 28 and the auxiliary blade 29, and then transported to a region facing the image carrier, where the electrostatic latent image on the image carrier is transferred. It is used for development. The toner that has not been used for development is neutralized by the neutralizing blade 24 as the developing roller 25 rotates. After reducing the electrostatic adhesive force between the developing roller 25 and the toner, the toner is scraped and collected from the developing roller 25 by the supply roller 30.

  FIG. 2 is a schematic diagram for explaining the average contact pressure of the regulating blade that contacts the developing roller.

2, 25 is a developing roller, 28 restriction blade, D ₁ is the contact position, L _A is the free length of the regulating blade, L _B denotes the effective length of the regulating blade.

As shown in FIG. 2 (a), and the contact pressure of the regulating blade abutting the developing roller, at the contact position D ₁ of the regulating blade abutting the developing roller, the junction of the abutting position D ₁ and the regulating blade This is a force (contact pressure) P ₁ (N / cm) per unit length (cm) of the regulating blade generated by the elasticity of the regulating blade in a direction perpendicular to the line connecting H _C1 . The effective length L _B of the restriction blade is the length between the contact position D ₁ and the joint portion H _C1 of the restriction blade.

  In the present invention, the contact pressure average of the regulating blade that contacts the developing roller is a value obtained by measurement using the measuring device shown in FIG. Specifically, pressure sensors are installed at three locations on the developing roller (the central portion of the developing roller and the end of the regulating blade) so that the pressure measurement surface is at the same level as the developing roller surface. This is a value obtained by measuring the contact pressure of the regulating blade while rotating the roller and averaging the measured values at three locations.

  In the present invention, the contact pressure average of the regulating blade contacting the developing roller is 10 to 50 N / m, preferably 15 to 45 N / m.

By making the contact pressure within the above range, the non-magnetic one-component toner can be transported with a uniform thickness without damaging the resin layer of the developing roller, and a uniform charge amount is imparted to the non-magnetic one-component toner. Next, the regulating blade, the developing roller, and the non-magnetic one-component toner used in the present invention will be described.

《Regulatory blade》
The regulating blade used in the present invention is installed in the developing cartridge for the purpose of uniformly thinning the toner on the surface of the developing roller and uniformly charging the toner.

  As the regulating blade, phosphor bronze having a spring elasticity capable of uniformly thinning and charging the non-magnetic one-component toner and controlling the average contact pressure to the developing roller within a specified range is used.

  Phosphor bronze can provide a stable charge to the non-magnetic one-component toner as compared with other metal elastic materials (for example, stainless steel).

  This is presumed that since the phosphor bronze charging sequence is more positive than stainless steel, the non-magnetic one-component toner can be charged more stably than stainless steel.

  The material of the phosphor bronze plate is preferably a JIS H3731 equivalent.

  The thickness of phosphor bronze is not particularly limited, but if a thickness of 0.03 to 0.12 mm is used, the contact pressure average can be easily adjusted to the above range.

  The regulating blade is fixed by a holder, and is used by being attached to the developing cartridge while being fixed to the holder.

<Development roller>
The developing roller used in the present invention is formed by directly forming a conductive resin layer on the outer periphery of the conductive shaft and without sandwiching an elastic layer made of silicone rubber, urethane rubber or the like between the conductive shaft and the conductive resin layer. It was produced.

<Layer structure of resin layer>
FIG. 3 is a schematic diagram of the layer structure showing an example of the developing roller used in the present invention.

  In FIG. 3, 25 is a developing roller, 11 is a conductive shaft, 12 is a resin layer, 13 is a lower layer, and 14 is an upper layer.

  FIG. 3A is a schematic view of a developing roller in which a resin layer 12 is formed on the outer periphery of the conductive shaft 11. As shown in FIG. 3B, the resin layer has a single-layer resin layer 12 on the outer periphery of the conductive shaft 11, and the lower layer on the outer periphery of the conductive shaft 11 as shown in FIG. 13 may be provided with a laminated resin layer 12 provided with an upper layer 14 thereon.

<Thickness of resin layer>
The thickness of the resin layer of the developing roller is preferably 5 to 30 μm, and in the case of a two-layer structure, the lower layer has a thickness of 5 to 20 μm and the upper layer has a thickness of 2 to 10 μm.

<Conductivity of resin layer>
The resin layer according to the present invention has conductivity.

The conductivity of the resin layer is expressed by volume resistivity, and the volume resistivity is preferably 1 × 10 ⁴ to 1 × 10 ¹⁰ Ω · cm.

  In the present invention, the volume resistivity of the resin layer is a value measured using the apparatus shown in FIG.

  FIG. 4 is a configuration diagram illustrating a method for measuring the volume resistivity of the developing roller.

  In the figure, 1 is a counter electrode (metal drum), 25 is a developing roller, 3 is a DC power source, and 4 is an ammeter.

  The volume resistance of the resin layer was pressed at 9.8 N together with the weight of the counter electrode 1 and 100 V was applied from the DC power source 3 while rotating the counter electrode 1 and the developing roller 25 to be measured in the direction of the arrow. The flowing current is measured with an ammeter 4 and calculated.

Measuring instrument: Measuring instrument of FIG. 4 Measuring condition: The linear velocity of the counter electrode and the developing roller is rotated at a constant speed of 1-5 cm / sec. Applied voltage: 100V
Measurement environment: 20 ° C, 50RH%
Next, a description will be given of materials and manufacturing methods used for manufacturing a developing roller in which a lower layer and an upper layer are provided as conductive resin layers on the outer periphery of the conductive shaft.

《Conductive shaft》
Since the conductive shaft used in the present invention also serves as a member that leaks charges accumulated on the surface of the developing roller, it is preferable that the conductive shaft is made of a conductive metal. Typical examples include conductive metals such as stainless steel (for example, SUS303) having a diameter of 5 to 30 mm, iron, aluminum, nickel, an aluminum alloy, and a nickel alloy, and may be made of a conductive resin. As the conductive shaft, those having a volume resistance of 1 × 10 ⁻⁴ Ω · cm or less are preferably used.

<Resin layer>
The resin layer comprises a coating liquid obtained by appropriately blending various additives such as a resin component and an electronic conductive agent, if necessary, an ionic conductive agent, a nonconductive filler (roughness particles), and a crosslinking agent. It can apply | coat to an outer peripheral surface and can form this by drying.

  Hereinafter, the production of the lower and upper resin layers will be described.

<< Preparation of the lower layer >>
Dissolve and disperse the electronic conductive agent, ionic conductive agent, and roughness particles in the solution in which the resin component is dissolved to prepare a coating solution, and apply this coating solution to the outer periphery of the conductive shaft by dip coating or spray coating. Apply and dry to form the lower layer.

<< Production of upper layer >>
In the solution in which the resin component is dissolved, an electronic conductive agent and an ionic conductive agent are dissolved and dispersed to prepare a coating solution, and this coating solution is applied on the lower layer by a dip coating method, a spray coating method, or the like, and then dried. Thus, the upper layer is formed.

<Resin component of resin layer>
The resin component of the resin layer is not particularly limited. Specifically, urea resin, melamine resin, alkyd resin, modified alkyd resin such as phenol modification / silicone modification, oil-free alkyd resin, acrylic resin, Examples thereof include a silicone resin, a fluororesin, a phenol resin, a polyamide resin, an epoxy resin, a polyester resin, a maleic acid resin, and a urethane resin. Of these, urethane resin, polyamide resin, acrylic resin, and the like are preferably used from the viewpoint of self-film reinforcing property, toner charging property, and the like. Among these, it is particularly preferable to use a urethane resin from the viewpoint of obtaining good wear resistance and elasticity.

  Examples of the urethane resin include those obtained by reacting a urethane raw material containing a polyhydroxy compound and an isocyanate compound, for example, those obtained by a method in which a prepolymer is subjected to a crosslinking reaction, and polyols obtained by polyisocyanate by a one-shot method. What was obtained by the method of making it react with soot is mentioned.

  In this case, as a polyhydroxyl compound used for obtaining a urethane resin, a polyol used for producing a general flexible polyurethane foam or a urethane elastomer, for example, a polyether polyol having a polyhydroxyl group at the terminal, a polyester polyol, a polyether In addition to polyester polyols, general polyols such as polyolefin polyols such as polybutadiene polyol and polyisoprene polyol, and so-called polymer polyols obtained by polymerizing ethylenically unsaturated monomers in the polyol can be used. As the isocyanate compound, polyisocyanate used in the production of general flexible polyurethane foam and urethane elastomer, that is, tolylene diisocyanate (sometimes referred to as TDI), crude TDI, 4,4'-diphenylmethane. Diisocyanate (sometimes referred to as MDI), crude MDI, aliphatic polyisocyanate having 2 to 18 carbon atoms, alicyclic polyisocyanate having 4 to 15 carbon atoms, and mixtures and modified products of these polyisocyanates, such as partially polyol A prepolymer obtained by reacting with a polymer can be used. In particular, the mixing ratio of the polyisocyanate may be lowered for the purpose of reducing the universal hardness of the resin layer.

  Moreover, the urethane resin may be prepared using a one-pack type or two-pack type urethane raw material containing a polyhydroxyl compound and a polyisocyanate, and an epoxy resin or a melamine resin is used as a crosslinking agent as necessary. Also good.

  Polyamide resins include polyamide resins typified by nylon 6,6,6,6,10,6,12,11,12,12,12, and polyamides obtained from polycondensation between different types of polyamide monomers. In view of workability, alcohol-soluble ones are preferred. For example, those obtained by adjusting the molecular weight of a polyamide terpolymer or quaternary copolymer, or those obtained by methoxymethylating nylon 6 or nylon 12 to be soluble in alcohol or water.

  Examples of the acrylic resin include polyacrylate, polymethyl methacrylate, polymethyl ethacrylate, those obtained by substituting these side chain ends with a hydroxyalkyl group, and copolymers thereof.

  As the resin used in the present invention, a silicone copolymer polyurethane resin is more preferable. The silicone copolymer polyurethane resin can be synthesized from a compound having in its molecule a silicone skeleton having a polyfunctional isocyanate having two or more functional groups and a hydroxyl group having two or more functional groups.

  The silicone copolymer polyurethane resin is not particularly limited, but those disclosed in Japanese Patent Publication No. 7-33427 can be used.

<Electronic conductive agent>
Examples of the electronic conductive agent include various conductive metals or alloys such as carbon black, graphite, aluminum, copper, tin, and stainless steel, tin oxide, zinc oxide, indium oxide, titanium oxide, tin oxide antimony monoxide solid solution, tin oxide Various conductive metal oxides such as indium oxide solid solution, and fine powders such as insulating substances coated with these conductive materials can be used. Among these, carbon black is preferably used because it can be obtained relatively easily and good chargeability can be obtained.

  The type of carbon black is not particularly limited, and various conventionally known carbon blacks such as ketjen black, channel black, and furnace black can be used. The blending amount of carbon black is not particularly limited because it varies depending on the type of carbon black to be used. Usually, it is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass with respect to 100 parts by mass of the resin component. Part.

  When the blending amount of the carbon black is within the above range, the conductivity and universal hardness of the developing roller become appropriate, and further, the uniformity of distribution in the resin layer is increased, so that the uniformity of conductivity is also improved. .

<Ionic conductive agent>
As the ionic conductive agent, conventionally known inorganic ionic salts and organic ionic salts can be appropriately selected and used. Specifically, alkali metal halides such as Li, LiCl, NaI, NaBr, and KI, perchlorates such as LiClO ₄ , KClO ₄ , and CuCl ₂ Mg (ClO ₄ ) ₂ , and thiocyanic acids such as LiSCN, NaSCN, and CsSCN Inorganic ion salts such as salts, aliphatic sulfonates, higher alcohol sulfates, higher alcohol phosphates, higher alcohol ethylene oxide addition sulfates, higher alcohol ethylene oxide addition phosphates, quaternary ammonium Examples thereof include organic ion salts such as salts and betaines. Among these, quaternary ammonium salts such as trimethyloctadecyl ammonium perchlorate, tetramethylammonium chloride, and benzyltrimethylammonium chloride are particularly preferable. These ionic conductive agents may be used alone or in combination of two or more.

  The blending amount of the ionic conductive agent is not particularly limited and is appropriately selected according to various situations, but is preferably 0.001 to 5 parts by mass with respect to 100 parts by mass of the resin component forming the resin layer, and 0.05 to 2 Part by mass is more preferable.

  As a result, there can be obtained a resin layer having a conductivity with little variation in the position of the electric resistance and less voltage dependence of the electric resistance and less fluctuation of the electric resistance with respect to the environmental change of temperature and humidity.

<Non-conductive filler (roughness particles)>
Examples of the non-conductive filler include diatomaceous earth, quartz powder, dry silica, wet silica, titanium oxide, zinc oxide, aluminosilicate, calcium carbonate, and resin particles. Among these, resin particles are preferable, and as the resin particles, crosslinked acrylic resin particles and crosslinked urethane resin particles are particularly preferable.

<Non-magnetic one-component developer (non-magnetic one-component toner)>
The production method of the non-magnetic one-component toner is not particularly limited, and can be produced by a known polymerization method or pulverization method.

The median diameter (D ₅₀ ) based on the number of non-magnetic one-component toner is preferably 3 to 9 μm.

Here, the median diameter (D ₅₀ ) based on the number refers to a toner particle diameter corresponding to a median value in a constant particle size distribution. That is, when the particle size distribution of a certain number of toner particles is taken, the number of toner particles having each particle size is counted in order from the larger or smaller particle size to determine the frequency, and the total number of toner particles The toner particle diameter that is a particle size distribution portion showing 50% of the toner particle diameter is called the median diameter (D ₅₀ ) based on the number of toner particles.

<Full-color image forming apparatus>
Next, a full color image forming apparatus in which the developing cartridge of the present invention is preferably used will be described.

  FIG. 5 is a schematic sectional view showing an example of a full-color image forming apparatus.

  In the full-color image forming apparatus shown in FIG. 5, a charging brush 111 that uniformly charges the surface of the photosensitive drum 10 to a predetermined potential around the photosensitive drum 10 that is rotationally driven, and the surface of the photosensitive drum 10. A cleaner 112 for scraping off the remaining toner is provided.

  Further, a laser scanning optical system 20 for scanning and exposing the photosensitive drum 10 charged by the charging brush 111 with a laser beam is provided. The laser scanning optical system 20 includes a laser diode, a polygon mirror, and an fθ optical element. As is well known, print data for each of yellow, magenta, cyan, and black is transferred from the host computer to the control unit. The laser scanning optical system 20 sequentially outputs the laser beam as a laser beam based on the print data for each color, scans and exposes the photosensitive drum 10, and thereby the static image for each color is formed on the photosensitive drum 10. Electro latent images are sequentially formed.

In addition, the full-color developing cartridge 30 that performs full-color development by supplying toner of each color to the photosensitive drum 10 on which the electrostatic latent image is formed in this manner is provided with yellow, magenta, cyan, and black around the support shaft 33. Four color-developing cartridges 31Y, 31M, 31C, and 31Bk containing each non-magnetic one-component toner are provided. The developing cartridges 31Y, 31M, 31C, and 31Bk rotate around the support shaft 33, and It is guided to a position facing the photosensitive drum 10.

  Further, in each of the developing cartridges 31Y, 31M, 31C, and 31Bk in the full-color developing cartridge 30, as shown in FIG. 5, the toner is formed on the outer peripheral surface of the developer carrier (developing roller) 25 that rotates and conveys the toner. A regulating member is pressed (contacted), and the toner regulating member regulates the amount of toner conveyed by the developing roller 25 and charges the conveyed toner. In the full color developing cartridge 30, two toner regulating members may be provided in order to appropriately regulate and charge the toner conveyed by the developing roller.

  As described above, each time an electrostatic latent image of each color is formed on the photosensitive drum 10 by the laser scanning optical system 20, the full-color developing cartridge 30 is rotated about the support shaft 33 as described above. The developing cartridges 31Y, 31M, 31C, and 31Bk containing the corresponding color toners are sequentially guided to positions facing the photosensitive drum 10, and the developing rollers 25 in the developing cartridges 31Y, 31M, 31C, and 31Bk are moved. The charged toner of each color is sequentially supplied onto the photosensitive drum 10 in which the electrostatic latent images of each color are sequentially formed as described above in contact with or without contact with the photosensitive drum 10. Development is to be performed.

  Further, an endless intermediate transfer belt 40 that is rotationally driven is provided as an intermediate transfer body 40 at a position downstream of the full-color developing cartridge 30 in the rotation direction of the photosensitive drum 10. Is driven to rotate in synchronization with the photosensitive drum 10. The intermediate transfer belt 40 is pressed by a rotatable primary transfer roller 41 so as to come into contact with the photosensitive drum 10, and a portion of a support roller 42 that supports the intermediate transfer belt 40 includes: A secondary transfer roller 43 is rotatably provided, and the recording material S such as recording paper is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43.

  Further, a cleaner 50 that scrapes off toner remaining on the intermediate transfer belt 40 is provided in a space between the full-color developing cartridge 30 and the intermediate transfer belt 40 so as to be able to contact and separate from the intermediate transfer belt 40. ing.

  Further, the paper feeding means 60 that guides the recording material S such as plain paper to the intermediate transfer belt 40 includes a paper feeding tray 61 that accommodates the recording material S and the recording material S that is accommodated in the paper feeding tray 61 one by one. The recording material S fed in synchronization with the paper feed roller 62 for feeding paper and the image formed on the intermediate transfer belt 40 is sent between the intermediate transfer belt 40 and the secondary transfer roller 43. The recording material S sent between the intermediate transfer belt 40 and the secondary transfer roller 43 in this way is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43. The toner image is pressed and transferred from the intermediate transfer belt 40 to the recording material S.

  On the other hand, the recording material S on which the toner image is pressed and transferred as described above is guided to the fixing device 70 by the conveying means 66 constituted by an air suction belt or the like, and is transferred by the fixing device 70. The toner image is fixed on the recording material S, and then the recording material S is discharged onto the upper surface of the apparatus main body 100 through the vertical conveyance path 80.

  Next, the operation of forming a full color image using this full color image forming apparatus will be specifically described.

  First, the photosensitive drum 10 and the intermediate transfer belt 40 are rotationally driven in the respective directions at the same peripheral speed, and the photosensitive drum 10 is charged to a predetermined potential by the charging brush 11.

  The photosensitive drum 10 thus charged is exposed to a yellow image by the laser scanning optical system 20 to form an electrostatic latent image of the yellow image on the photosensitive drum 10. The yellow image is developed by supplying the yellow toner charged by the toner regulating member as described above from the developing cartridge 31Y in which the yellow toner is accommodated in the photosensitive drum 10, and the yellow toner image is thus formed. The intermediate transfer belt 40 is pressed against the body drum 10 by the primary transfer roller 41, and the yellow toner image formed on the photosensitive drum 10 is primarily transferred to the intermediate transfer belt 40.

  After the yellow toner image is transferred to the intermediate transfer belt 40 in this way, the full-color developing cartridge 30 is rotated around the support shaft 33 as described above, and the developing cartridge 31M containing magenta toner is exposed to light. As in the case of the yellow image described above, the magenta image is exposed to the photosensitive drum 10 charged by the laser scanning optical system 20 to form an electrostatic latent image. The electrostatic latent image is developed by the developing cartridge 31M containing magenta toner, and the developed magenta toner image is primarily transferred from the photosensitive drum 10 to the intermediate transfer belt 40. The black image is exposed, developed, and primary transferred in sequence, and yellow, magenta, cyan, and black are printed on the intermediate transfer belt 40. Superimposed in sequence to form a toner image of full color toner image.

  When the final black toner image is primarily transferred onto the intermediate transfer belt 40, the recording material S is fed between the secondary transfer roller 43 and the intermediate transfer belt 40 by the timing roller 63, and the secondary transfer roller. The recording material S is pressed against the intermediate transfer belt 40 by 43, and the full color toner image formed on the intermediate transfer belt 40 is secondarily transferred onto the recording material S.

  When the full-color toner image is secondarily transferred onto the recording material S in this way, the recording material S is guided to the fixing device 70 by the conveying means 66, and the full-color toner transferred by the fixing device 70 is transferred. The image is fixed on the recording material S, and then the recording material S is discharged onto the upper surface of the apparatus main body 1 through the vertical conveyance path 80.

  The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited to these examples.

《Preparation of regulation blade》
The following regulation blades were prepared.

<Preparation of regulation blade 1> (for comparative example)
Material: Phosphor bronze plate (JIS H3731 equivalent)
Thickness: 0.02mm
<Preparation of regulation blade 2>
Material: Stainless steel (SUS304)
Thickness: 0.04mm
<Preparation of regulation blade 3>
Material: Phosphor bronze plate (JIS H3731 equivalent)
Thickness: 0.08mm
<Preparation of regulation blade 4>
Material: Phosphor bronze plate (JIS H3731 equivalent)
Thickness: 0.20mm
<Preparation of regulation blade 5> (for comparative example)
Material: Phosphor bronze plate (JIS H3731 equivalent)
Thickness: 0.22mm
<Preparation of regulating blade 6> (for comparative example)
Material: Stainless steel plate (SUS304)
Thickness: 0.04mm
<Preparation of regulating blade 7> (for comparative example)
Material: Stainless steel plate (SUS304)
Thickness: 0.08mm
<Preparation of regulating blade 8> (for comparative example)
Material: Stainless steel plate (SUS304)
Thickness: 0.20mm
<Production of developing roller>
A developing roller was produced as follows.

(Lower layer formation)
Carbon black "Ketjen Black EC300J (Lion Corporation)" 20 parts by mass in a solution in which 100 parts by mass of urethane resin "Nipporan 5199 (Nihon Polyurethane Co., Ltd.)" which is a thermoplastic elastomer is dissolved in 500 parts by mass of methyl ethyl ketone, Tetra Disperse 2.0 parts by mass of methylammonium chloride and 20 parts by mass of “spherical crosslinked acrylic resin” having a median diameter (D ₅₀ ) of 15 μm on a volume basis using a sand mill for 2 hours. Was prepared.

  After spraying the “lower layer forming coating solution” on the outer peripheral surface of a hollow cylindrical “shaft” of SUS303, drying was performed at 120 ° C. for 1 hour to form a “lower layer” having a thickness of 10 μm after drying.

(Upper layer formation)
Carbon black “Ketjen Black EC300J (Lion Corporation)” 20 parts by mass, tetramethylammonium chloride 2. In a solution in which 100 parts by mass of urethane resin “Nipporan 5199 (manufactured by Nippon Polyurethane)” is dissolved in 500 parts by mass of methyl ethyl ketone. 0 parts by mass and 20 parts by mass of “tetrafluoroethylene resin particles” having a number average primary particle size of 0.05 μm were dispersed using a sand mill for 2 hours to prepare an “upper layer forming coating solution”.

  Resin consisting of a lower layer and an upper layer formed by spraying the “upper layer forming coating solution” on the outer surface of the “lower layer” so that the film thickness after drying becomes 5 μm and drying at 100 ° C. for 1 hour. A layer was formed to produce a “developing roller”.

<< Preparation of non-magnetic one-component developer >>
A nonmagnetic one-component developer (nonmagnetic one-component toner) was produced as follows.

(Preparation of resin particles)
In a container equipped with a stirrer, 72.0 parts by mass of wax (pentaerythritol tetrastearate) is added from 115.1 parts by mass of styrene, 42.0 parts by mass of n-butyl acrylate, and 10.9 parts by mass of methacrylic acid. Was added to the monomer mixture solution, heated to 80 ° C. and dissolved to prepare a monomer solution.

  On the other hand, 7.08 parts by mass of an anionic surfactant (sodium dodecylbenzenesulfonate: SDS) was dissolved in 2760 parts by mass of ion-exchanged water in a separable flask equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction apparatus. The prepared surfactant solution (aqueous medium) was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. Next, the monomer solution (80 ° C.) was mixed and dispersed in the surfactant solution (80 ° C.) with a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) having a circulation path, and uniformly An emulsified liquid in which emulsified particles (oil droplets) having a dispersed particle diameter were dispersed was prepared.

  An initiator solution in which 0.84 parts by mass of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 parts by mass of ion-exchanged water was added to this dispersion, and this system was heated at 80 ° C. for 3 hours. The polymerization reaction was carried out by stirring. A solution obtained by dissolving 7.73 parts by mass of a polymerization initiator (KPS) in 240 parts by mass of ion-exchanged water was added to the obtained reaction solution. After 15 minutes, the temperature was adjusted to 80 ° C., and then styrene 383.6. A mixed solution consisting of part by mass, 140.0 parts by mass of n-butyl acrylate, 36.4 parts by mass of methacrylic acid and 12 parts by mass of n-octyl mercaptan was dropped over 100 minutes, and the system was heated at 80 ° C. for 60 minutes. After stirring, this system was cooled to 40 ° C. to prepare a dispersion of resin particles containing wax (hereinafter also referred to as “latex (1)”).

(Preparation of colorant dispersion (1))
On the other hand, 9.2 parts by mass of sodium n-dodecyl sulfate was stirred and dissolved in 160 parts by mass of ion-exchanged water. While stirring this solution, 20 parts by mass of carbon black “Mogal L” (manufactured by Cabot Corp.) is gradually added as a colorant, and then a mechanical disperser “Claremix” (manufactured by M Technique Corp.) is used. A dispersion of colorant particles (hereinafter referred to as “colorant dispersion (1)”) was prepared by dispersion treatment. When the particle diameter of the colorant particles in the colorant dispersion (1) was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 120 nm.

(Preparation of colorant dispersion (2))
In the colorant dispersion (1), the colorant was prepared in the same manner as in Preparation Example 1 of the colorant dispersion except that 20 parts by mass of the pigment “CI Pigment Yellow 74” was used instead of 20 parts by mass of the carbon black. A particle dispersion (hereinafter referred to as “colorant dispersion (2)”) was prepared. When the particle diameter of the colorant particles in the obtained colorant dispersion (2) was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 120 nm. there were.

(Preparation of colorant dispersion (3))
In the colorant dispersion (1), the same procedure as in Preparation Example 1 of the colorant dispersion was performed except that 20 parts by mass of quinacridone-based magenta pigment “CI Pigment Red 122” was used instead of 20 parts by mass of carbon black. A dispersion of colorant particles (hereinafter referred to as “colorant dispersion (3)”) was prepared. When the particle diameter of the colorant particles in the obtained colorant dispersion (3) was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 120 nm. there were.

(Preparation of colorant dispersion (4))
In the colorant dispersion liquid (1), except that 20 parts by mass of phthalocyanine cyan pigment “CI Pigment Blue 15: 3” was used instead of 20 parts by mass of carbon black, Similarly, a dispersion of colorant particles (hereinafter referred to as “colorant dispersion (4)”) was prepared. When the particle diameter of the colorant particles in the obtained colorant dispersion (4) was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 120 nm. there were.

(Preparation of colored particles (K1))
In a reaction vessel (four-necked flask) equipped with a temperature sensor, a cooling tube, a stirrer (having two stirrer blades, an intersection angle of 20 °), and a shape monitoring device, 1250 parts by mass (solid content) Conversion), 2000 parts by mass of ion-exchanged water, and the total amount of the colorant dispersion (1) were prepared, and the internal temperature was adjusted to 25 ° C. Then, a 5 mol / liter sodium hydroxide aqueous solution was added to the dispersion mixture. The pH was adjusted to 10.0. Subsequently, an aqueous solution in which 52.6 parts by mass of magnesium chloride hexahydrate was dissolved in 72 parts by mass of ion-exchanged water was added over 10 minutes at 25 ° C. with stirring. Thereafter, the temperature increase was started immediately, and the system was heated to 95 ° C. over 5 minutes (temperature increase rate: 14 ° C./min).

In this state, the particle size of the associated particles was measured with “Multisizer 3 (manufactured by Coulter)”. When the volume-based median diameter (D ₅₀ ) reached 6.5 μm, 115 parts by mass of sodium chloride was ionized. An aqueous solution dissolved in 700 parts by mass of exchange water is added to stop the particle growth, and further, the mixture is heated and stirred at a liquid temperature of 90 ° C. for 8 hours (stirring rotation speed: 120 rpm), thereby continuing the fusion and aging treatment. Then, the system was cooled to 30 ° C. at 10 ° C./min, hydrochloric acid was added to adjust the pH to 3.0, and stirring was stopped.

  The produced particles are filtered, washed repeatedly with ion-exchanged water, classified in liquid with a centrifugal separator, and then dried using a flash jet dryer to give colored particles having a moisture content of 1.0% (hereinafter referred to as “ Colored particles (K1) ”) were obtained.

(Preparation of colored particles (Y1))
“Colored particles (Y1)” were obtained in the same manner as in the preparation of the colored particles (K1) except that the total amount of the colorant dispersion (1) was changed to the total amount of the colorant dispersion (2).

(Preparation of colored particles (M1))
“Colored particles (M1)” were obtained in the same manner as in the preparation of the colored particles (K1) except that the total amount of the colorant dispersion (1) was changed to the total amount of the colorant dispersion (3).

(Preparation of colored particles (C1))
“Colored particles (C1)” were obtained in the same manner as in the preparation of the colored particles (K1) except that the total amount of the colorant dispersion (1) was changed to the total amount of the colorant dispersion (4).

(External additive treatment of colored particles)
0.8 parts by mass of hydrophobic silica (number average primary particle size = 12 nm, hydrophobicity = 65) and hydrophobic titania (number average primary particle size = 30 nm, hydrophobicity) = 55) was added in an amount of 0.5 parts by mass and mixed with a Henschel mixer to prepare a non-magnetic one-component toner. These are referred to as “black non-magnetic one-component toner”, “yellow non-magnetic one-component toner”, “magenta non-magnetic one-component toner”, and “cyan non-magnetic one-component toner”.

<Preparation of developing cartridge>
The regulating blade and the developing roller produced as described above were mounted on the developing cartridge shown in FIG. 1, and the contact pressure average of the regulating blade contacting the developing roller was set as shown in Table 1. Thereafter, each color non-magnetic one-component toner prepared above was loaded to prepare “developing cartridges 1 to 12”.

  Table 1 shows the contact pressure average of the regulating blade mounted on the developing cartridge and the regulating blade that contacts the developing roller.

  The average contact pressure of the regulating blade that contacts the developing roller is a value measured using the measuring device shown in FIG.

<Evaluation>
Evaluation of the developing cartridge is carried out by mounting the “developing cartridges 1 to 12” prepared in the above on a color laser printer “Magicor2430DL” (manufactured by Konica Minolta Business Technologies) in an environment of normal temperature and humidity (20 ° C., 55% RH). It was printed with.

  In the initial performance evaluation of the developing cartridge, an A4-size original was printed at a pixel rate of 20% (full color mode of 5% for each color of yellow, magenta, cyan, and black), and the toner image quality was evaluated.

  Thereafter, continuous 5000 sheets were printed using a document with an image ratio of 2% (full color mode of 0.5% for each color of yellow, magenta, cyan, and black).

  Performance evaluation after printing 5000 sheets was done by printing an A4 size document with a pixel rate of 20% (full color mode of 5% for each color of yellow, magenta, cyan, and black) as in the initial performance evaluation, and the film of the developing roller resin layer was peeled off. The toner image quality (image density, image density fluctuation) and toner spillage were evaluated.

<Removal of resin layer>
The film peeling of the resin layer was evaluated by visual observation of the state of film peeling on the surface of the developing roller corresponding to the end of the regulating blade and the toner image obtained by printing. Specifically, after the completion of printing 5000 sheets in a high temperature and high humidity environment (33 ° C., 80% RH), the state of film peeling on the surface of the developing roller was evaluated from a toner image obtained by visual observation and printing.

Evaluation criteria A: No visible film peeling ○: There is visible film peeling, but it does not appear in the print image ×: There is visible film peeling, and it appears as an image defect in the printed image.

<Image density>
The image density was evaluated by measuring the density of the solid black image portion printed at the initial stage and after printing 5000 sheets, using a reflection densitometer “RD-918” (manufactured by Macbeth Co.), and calculating the average value.

  The density of the solid image portion is 1.40 or higher.

<Image density fluctuation>
The image density fluctuation was evaluated by the density difference between the initial black image portion printed after the completion of printing 5000 sheets. An image density variation of less than 0.15 is accepted.

<Toner spill>
After completion of printing 5000 sheets, the periphery of the developing cartridge was visually observed, and the state of toner spilling around the developing cartridge was visually observed and evaluated.

：: Toner spillage is not observed and good ◯: Toner spillage is slightly observed but has no practical problem ×: Toner spillage is clearly observed and causes a practical problem

  Table 2 shows the evaluation results.

  As shown in Table 2, in “Developing cartridges 1 to 5” of Examples 1 to 5 corresponding to the present invention, the coating layer peeled off, and the image density, the image density fluctuation, and the toner spilling were all good. On the other hand, in “Developing cartridges 6 to 12” of Comparative Examples 1 to 7 outside the present invention, a problem was found in any of the evaluation items, and it was confirmed that the effects of the present invention were not exhibited.

FIG. 2 is a schematic cross-sectional view showing an example of the developing cartridge of the present invention. It is the schematic explaining the contact pressure average of the control blade contact | abutted to a developing roller. It is a layer structure schematic diagram showing an example of a development roller used in the present invention. It is a block diagram explaining the measuring method of the volume resistivity of a developing roller. It is a schematic sectional drawing which shows an example of a full-color image forming apparatus.

Explanation of symbols

20 developing cartridge 25 developing roller 26 buffer chamber 27 hopper 27
28 Restricting blade 29 Auxiliary blade 30 Supply roller T Toner 31 Rotating body 32 Passage 321 Valve

Claims (1)

In a developing roller having a conductive roller formed on the outer periphery of a conductive shaft, a non-magnetic one-component developer, and a developing cartridge having a regulating blade,
The material of the regulation blade is a phosphor bronze plate,
A developing cartridge, wherein the regulating blade is in contact with the developing roller at a contact pressure average of 10 to 50 N / m.

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