JP2005274818A - Toner and image forming apparatus using the toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate cleaning in regeneration of a used developing cartridge by preventing toner and external additives from adhering to a developing roller. <P>SOLUTION: The toner contains a first external additive composed of inorganic particles having a grain size distribution of primary particle size of 200 to 750 nm and having the work function nearly equal to that of toner base particles and a second external additive composed of inorganic particles having a mean particle size smaller than that of the first external additive and having the work function smaller than that of the developing roller of a developing device, in which metallic soap having the work function nearly equal to that of the toner base particles is incorporated into the toner at 0.01 to 0.3% by weight. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a toner that can be easily cleaned when a used developing cartridge is regenerated and an image forming apparatus using the toner.

  Conventionally, even in continuous printing, in order to provide stable print quality over a long period of time, it is possible to add a plurality of types of external additives having different primary particle diameters to the toner, or to add an abrasive having a larger particle diameter. It is known in Patent Documents 1 to 4 and the like to prevent filming on a photoconductor that is an electrostatic latent image carrier.

In addition, in a developing device that holds a non-magnetic one-component toner that is a developer through a regulating portion by a supply member and holds a thin layer of toner on the developing member, the toner that is not regulated by the regulating member is dropped downward, A so-called toner circulation type developing device is known from Patent Document 5 and Patent Document 6 which are stirred with the toner already present in the primary reservoir and then transported to the second reservoir.
JP 63-289559 A JP 2001-147547 A Japanese Patent Laid-Open No. 11-184144 JP 2003-322998 A Japanese Patent Laid-Open No. 2001-42614 JP 2003-173081 A

  However, as shown in Patent Document 1 to Patent Document 4, in the case of adding a plurality of types of external additives having different primary particle sizes, the toner surface can be obtained by adding 2% by weight or more of the external additive to the toner. Factors in which the external additive is more liberated and the liberated external additive adheres to the toner contact portion in the developing cartridge, which takes a long time to clean the used cartridge and reduces production efficiency. It was. This is more remarkable in the toner circulation type developing devices disclosed in Patent Documents 5 to 6.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and to prevent toner and external additives from adhering to a developing roller of a developing device, and to facilitate cleaning during recycling of a used developing cartridge. And
Therefore, the toner of the present invention has a primary particle size distribution of 200 to 750 nm, a first external additive composed of inorganic fine particles having a work function substantially equal to that of the toner base particles, and the first external additive. In the toner containing a toner mother particle and a second external additive made of inorganic fine particles having a work function smaller than that of the developing roller of the developing device, the work almost equal to the toner mother particle. A metal soap having a function is contained in a weight ratio of 0.01% to 0.3%.
The toner of the present invention is characterized in that the inorganic fine particles are subjected to a hydrophobic treatment, and the toner is a non-magnetic one-component negatively chargeable toner.
The toner of the present invention is characterized in that the work function of the developing roller of the developing device is equal to or higher than the work function of the toner base particles.
According to another aspect of the present invention, there is provided an image forming apparatus including a developing device for developing using the toner.
In addition, the image forming apparatus of the present invention includes a developing device having a stirring member that retains toner after restriction by the restriction unit in the primary storage unit, and then transports the toner to the restriction unit through the secondary storage unit. Features.
The image forming apparatus of the present invention is characterized in that the work function of the developing roller of the developing device is equal to or higher than the work function of the toner base particles.

When the inorganic fine particles having a large particle size having substantially the same work function as that of the toner base particles are used as they are in the developing apparatus, they are released from the surface of the toner base particles together with the external additive having a smaller work function. As a result, the effect of polishing the inorganic fine particles having a large particle diameter and the spacer effect disappear, and an external additive having a smaller work function adheres to the developing roller of the developing device. Therefore, in order to prevent the release or detachment of the inorganic external additive having a large particle size without hindering the charging characteristics of the toner, a metal soap having substantially the same work function as that of the toner base particles is added to other external additives. By using the toner added and mixed with the additive as the developer, it is possible to prevent the external additive from adhering to the developing roller of the developing device. Further, since the inorganic external additive having a large particle size is not released from the toner, the polishing effect and the spacer effect are maintained, and the developing roller of the developing device due to the adhesion of the external additive and toner can be prevented from being stained. This facilitates cleaning of the adhering external additive during the regeneration of the developing cartridge, thereby facilitating the regeneration operation of the developing cartridge.
Further, in the present invention, negatively chargeable toner base particles are used, and by using a developing roller of a developing device having a work function larger than that of the toner base particles, electrons move from the toner base particles to the photosensitive member, thereby causing the toner to move. As a result, the negative charge amount is reduced, and as a result, the electrostatic force with the photosensitive member is weakened, the adhesion force of the toner is reduced, and the used developing cartridge can be easily cleaned.

Embodiments of the present invention will be described below.
FIG. 1 is a diagram illustrating an example of a developing device to which the present invention is applied.
The developing device main body 20 includes a toner storage container 26 that stores toner (mesh portion in the drawing), a toner storage section (primary storage section) 27 formed in the toner storage container 26, and a primary storage section 27. A toner agitating member 29 provided; a toner receiving member 30 provided above the primary reservoir 27; a toner supply roller 31 provided above the toner receiving member 30; and a toner receiving member 30; A receiving sheet 32 that is in contact with the lower portion of the toner supply roller 31 and a development that is in contact with the toner supply roller 31 and facing the photosensitive member 17 with a slight gap (about 100 to 300 μm). A roller 33, a regulation blade 34 that contacts the lower side of the developing roller 33, and a regulation blade 34 are attached. Housing wall 45 which functions as a toner path member for free fall, are configured in the direction of recovering the toner remaining on the developing roller after development from contact with Metropolitan upper seal 46 for preventing toner leakage.

  The developing roller 33 and the photoconductor 17 are opposed to each other with a slight space therebetween, and are driven to rotate in opposite directions as indicated by arrows in the drawing. Moves in the same direction from the bottom to the top, and a developing bias in which an AC voltage is superimposed on a DC voltage is applied to the developing roller from a developing bias power source (not shown) to generate an oscillating electric field between the developing roller and the photosensitive member. The toner is supplied to the electrostatic latent image portion formed on the photosensitive member from the developing roller and developed. In this embodiment, the developing roller and the photosensitive member are opposed to each other with a slight gap in the developing area. However, the developing roller and the photosensitive member may be brought into contact with each other in the developing area for development. Is possible.

  In the developing device of this embodiment, the primary storage unit 27 stores toner that does not bury the regulating blade 34. This is because if the amount of toner is so large that the regulating blade 34 is buried, the circulation path through which the toner scraped off from the regulating blade 34 is smoothly returned to the primary storage unit 27 is obstructed. This is because the role of scraping off excess toner from the upper toner and regulating the amount of toner conveyed to the development area and the role of appropriately charging the toner are hindered. The primary storage unit 27 is rotatably provided with a stirring member 29 having a flexible conveying member 29c made of Mylar or the like attached to the tip.

  That is, as shown in FIGS. 2 (a) and 2 (b), the stirring member 29 has a plurality of ribs attached to the resin pipe 29a at predetermined intervals, and a flexible conveying member 29c made of Mylar or the like at the tip of the rib. It is attached. Then, by rotating the stirring member 29, the toner stored in the primary storage unit 27 is supplied to the gap (secondary storage unit) between the toner receiving member 30 and the supply roller 31 by the transport member 29a.

  Further, a supply roller 31 provided with a conductive elastic layer having a plurality of cells on the outer peripheral portion is disposed in the vicinity of the secondary storage portion, and the elastic layer of the supply roller 31 is pressed against the developing roller 33. I am doing so. The supply roller 31 and the developing roller 33 are rotated in the same direction, and the respective peripheral surfaces are moved in the opposite directions in the contact areas to be rubbed against each other, and applied to the developing roller from a developing bias power source (not shown). A voltage equivalent to the developing bias voltage is applied to the supply roller.

  One end of a receiving sheet 32 formed in a plate shape is attached to the toner receiving member 30, and the receiving sheet 32 is brought into contact with the lower portion of the supply roller 31 with an appropriate linear pressure. The presence of the receiving sheet prevents the toner adhering to the supply roller 31 from dropping due to gravity at the lower position, and prevents the toner that can be supplied to the developing roller from decreasing, thereby preventing a decrease in image density.

  The toner supplied to the developing roller 33 from the supply roller 31 scrapes off excess toner from the developing roller by the regulating blade 34 to regulate the amount of toner conveyed to the developing area and to appropriately charge the toner. I have to. The excess toner scraped off from the developing roller 33 by the regulation blade 34 is dropped by gravity, and a certain toner falls on the casing wall 45 below the regulation blade, and then slides down the wall to be returned to the primary storage unit 27. In addition, a certain toner is directly dropped and returned to the primary storage unit 27. At this time, the angle formed with the horizontal line of the casing wall 45 is set to be larger than the repose angle of the toner. Then, the toner that is regulated by the regulating blade and appropriately charged is conveyed to the developing area facing the photosensitive member by the developing roller, and the electrostatic latent image portion on the photosensitive member is developed by the action of the vibration electric field described above. .

  After developing the electrostatic latent image formed on the photosensitive member in this manner, the upper seal 46 is brought into light contact with the developing roller 33 at a position where the toner remaining on the developing roller is returned to the developing device main body, thereby preventing leakage. ing. After development, the toner remaining on the developing roller 33 is separated from the surface of the developing roller by rubbing between the developing roller and the supplying roller 31 whose peripheral surface moves in the opposite direction at the contact portion, and the toner receiving member 30 and the supplying roller are separated from each other. The toner is mixed with the toner accumulated in the gap (secondary storage part) and supplied as new toner from the supply roller to the developing roller.

  According to the above configuration, when collecting the toner scraped off by the regulating blade 34 in the primary storage unit 27, the stress applied to the toner is eliminated by collecting the toner using gravity or the angle of repose of the toner. The lifetime of the toner can be extended. For this reason, it is possible to reduce the white background stain and the density change due to the fogging of the toner and the decrease in the charge amount, and it is possible to maintain good image quality. Further, since the toner consumption is reduced, the running cost can be reduced.

  Further, in the toner storage portion, the center of the supply roller 31 is above the upper surface of the toner accumulation, and a scraper 30a (a sheet having a PET thickness of about 0.15 mm) is provided at the tip of the toner receiving member 30 below the supply roller. Is pasted. The toner shown in black in the drawing shows a state of being conveyed onto the scraper 30a. The scraper 30a is set so that the conveying member 29a attached to the tip of the stirring member 29 enters from and comes into contact with the scraper 30a and is pushed upward by the conveying member 29a to be deformed. Therefore, after the toner conveyed by the conveying member 29a is delivered to the scraper, the scraper is deformed upward, and the toner moves to the gap (secondary storage portion) between the toner receiving member 30 and the supply roller 31. The angle formed between the scraper 30a and the horizontal line when attached to the toner receiving member is preferably equal to or greater than the repose angle of the toner. However, if the repose angle is smaller than the repose angle, the toner does not move to the secondary storage unit, and the scraper As described above, the scraper is deformed upward after the conveying member 29a comes into contact with the scraper as described above, so that in this state, the repose angle is exceeded and the toner moves to the secondary storage unit. become.

  Since both the scraper 30a and the conveying member 29a are made of a resin sheet, the scraper 30a and the conveying member 29a have a property of being easily bent by stress, and as an appropriate use, the scraper 30a has a property of being more easily bent than the conveying member 29a. Is desirable. For this purpose, it is desirable to reduce the thickness of the scraper if the scraper and the conveying member are the same material, and to set the scraper to a low rigidity if the material is different. As a result, after sufficient toner is transferred from the conveying member to the scraper, the toner is supplied to the secondary storage unit without delay due to deformation of the scraper.

  On the other hand, in the roller shaft cross section, when a tangent line is drawn with respect to the conveyance member 29a at a position where the conveyance member 29a first contacts the toner receiving member 30, an angle between the tangent line and the horizontal line is θ2, and the toner receiving member 30 is When the angle formed with the horizon is θ1, it is preferable that θ1> θ2. If [theta] 1 <[theta] 2, the entrance angle (90 [deg.]-[Theta] 2) of the conveying member when the conveying member and the scraper come into contact with each other increases, and the scraper is prevented from being deformed smoothly, Overload more than necessary will shorten the life of the conveying member, and problems such as increasing the torque required to rotate the stirring member that fixes the conveying member will occur. . Furthermore, it is conceivable that a large noise is generated at the moment of contact. Therefore, it is preferable that θ1> θ2.

  Further, the angle θ3 formed by the line connecting the portion where the conveying member 29a first contacts the toner receiving member 30 and the rotation center of the agitating member 29 fixing the conveying member, and the vertical line, corrects the rotation direction of the agitating member. When it is taken, it is preferable that 0 ≦ θ3. If θ3 <0 is set, the toner at the leading end of the transport member may fall from the transport member or the scraper, and sufficient toner is not efficiently supplied to the secondary storage unit, resulting in insufficient supply. Will occur, leading to a decrease in image density. From the above, good toner supply can be achieved by appropriate arrangement and rigidity of the conveying member and the scraper.

FIG. 3 is a view for explaining an example of a cleanerless color image forming apparatus equipped with the developing device of FIG.
An image forming apparatus 201 according to the present exemplary embodiment illustrated in FIG. 3 does not include a cleaning unit on the photosensitive member, and opens and closes a housing 202, a paper discharge tray 203 formed on the top of the housing 202, and a front surface of the housing 202. The housing 202 has a freely mounted door 204, and a control unit 205, a power supply unit 206, an exposure unit 207, an image forming unit 208, an exhaust fan 209, a transfer unit 210, and a paper feeding unit 211 are arranged in the housing 202. In addition, a paper transport unit 212 is disposed in the door body 204. Each unit has a configuration that can be attached to and detached from the main body, and can be removed and repaired or replaced integrally during maintenance or the like.

  The transfer unit 210 includes a driving roller 213 disposed below the housing 202 and driven to rotate by a driving source (not shown), a driven roller 214 disposed obliquely above the driving roller 213, and the two rollers. An intermediate transfer belt 215 is provided that is stretched between and circulated and driven in the direction of the arrow shown in the figure (counterclockwise). The driven roller 214 and the intermediate transfer belt 215 are arranged in a direction inclined to the left in the drawing with respect to the drive roller 213. It is installed. As a result, the belt tension side (side pulled by the drive roller 213) 217 during driving of the intermediate transfer belt 215 is positioned below, and the belt slack side 218 is positioned above. At a position facing the driven roller 213, a cleaner 216 that scrapes off the transfer residual toner on the intermediate transfer belt is provided.

The drive roller 213 also serves as a backup roller for a secondary transfer roller 219 described later. A rubber layer having a thickness of about 3 mm and a volume resistivity of 1 × 10 ⁵ Ω · cm or less is formed on the peripheral surface of the driving roller 213, and the secondary transfer is performed by grounding through a metal shaft. A conductive path of the secondary transfer bias supplied via the roller 219 is used. Thus, by providing the driving roller 213 with a rubber layer having high friction and shock absorption, it is difficult for the impact when the recording material enters the secondary transfer portion to be transmitted to the intermediate transfer belt 215, thereby preventing image quality deterioration. can do.

  In the present invention, the diameter of the driving roller 213 is made smaller than the diameter of the driven roller 214. Thereby, the recording paper after the secondary transfer can be easily peeled by the elastic force of the recording paper itself.

  Further, a primary transfer member 221 is placed on the back surface of the intermediate transfer belt 215 so as to face the image carrier 220 of each of the single color image forming units Y, M, C, and K constituting the image forming unit 208 described later. A transfer bias is applied to the primary transfer member 221.

  The image forming unit 208 is a single color image forming unit Y (for yellow), M (for magenta), C (for cyan), K (for black) that forms a plurality of (four in this embodiment) images of different colors. The monochromatic image forming units Y, M, C, and K are respectively disposed around the image carrier 220 and an image carrier 220 made of a photoreceptor having an organic photosensitive layer and an inorganic photosensitive layer formed thereon. The charging unit 222 and the developing unit 223 include a corona charger or a charging roller.

  The image carrier 220 of each single color image forming unit Y, M, C, K is brought into contact with the belt tension side 217 of the intermediate transfer belt 215. As a result, each single color image forming unit Y, M, C, K is also disposed in a direction inclined to the left in the drawing with respect to the drive roller 213. The image carrier 220 is rotationally driven in the direction opposite to the intermediate transfer belt 215 as indicated by the arrows in the figure.

  The exposure unit 207 is disposed obliquely below the image forming unit 208 and includes a polygon mirror motor 224, a polygon mirror 225, an f-θ lens 226, a reflection mirror 227, and a folding mirror 228. Are modulated and formed based on a common data clock frequency, passed through an f-θ lens 226, a reflection mirror 227, and a folding mirror 228, and then output to each of the monochrome image forming units Y, M, C, and K. The image carrier 220 is irradiated to form a latent image. Note that the optical path lengths of the single-color image forming units Y, M, C, and K to the image carrier 220 are made substantially the same length by the action of the folding mirror 228.

  Next, the developing unit 223 will be described on behalf of the monochromatic image forming unit Y. In the present embodiment, since the single color image forming units Y, M, C, and K are arranged in a direction inclined to the left side in the drawing, the toner storage container 229 is arranged obliquely downward.

  That is, the developing unit 223 includes a toner storage container 229 that stores toner, a toner storage unit 230 (hatched portion in the drawing) formed in the toner storage container 229, and a toner disposed in the toner storage unit 230. The agitating member 231, a partition member 232 partitioned on the toner storage unit 230, a toner supply roller 233 disposed above the partition member 232, and abutting the toner supply roller 233 provided on the partition member 232 A charging blade 234, a developing roller 235 disposed so as to be close to the toner supply roller 233 and the image carrier 220, and a regulating blade 236 that contacts the developing roller 235.

  The developing roller 235 and the toner supply roller 233 are rotationally driven in the direction opposite to the rotation direction of the image carrier 220 as shown by the arrows in the figure, while the stirring member 231 is in the direction opposite to the rotation direction of the supply roller 233. Driven by rotation. The toner stirred and carried by the stirring member 231 in the toner storage unit 230 is supplied to the toner supply roller 233 along the upper surface of the partition member 232, and the supplied toner is a charging blade 234 made of a flexible material. The surface of the supply roller 233 is supplied to the surface of the developing roller 235 by the mechanical adhesion force to the irregularities on the surface of the supply roller 233 and the adhesion force due to the frictional band power.

  The toner supplied to the developing roller 235 is regulated to be thinned to a predetermined thickness by the regulating blade 236. The thinned toner layer is conveyed to the image carrier 220 and develops the electrostatic latent image on the image carrier 220 in a development region where the developing roller 235 and the image carrier 220 are close to each other.

  Further, at the time of image formation, the paper feed unit 211 includes a paper feed cassette 238 in which a plurality of recording materials S are stacked and held, and a pickup roller 239 that feeds the recording materials S from the paper feed cassette 238 one by one. ing.

  The paper transport unit 212 includes a gate roller pair 240 (one roller is provided on the housing 202 side) that defines the timing of feeding the recording material S to the secondary transfer unit, a drive roller 213 and an intermediate transfer belt 215. A secondary transfer roller 219 serving as a secondary transfer unit pressed against the main recording material, a main recording material conveyance path 241, a fixing unit 242, a discharge roller pair 243, and a duplex printing conveyance path 244. The fixing unit 242 includes a sheet material that presses and urges at least one roller of the fixing roller pair 245 toward the other side, and a pair of rotatable fixing rollers 245 each including a heating element such as a halogen heater. The secondary image that has been secondarily transferred to the recording material S is pressed against the recording material S, and the secondary image that has been secondarily transferred to the recording material is recorded at a predetermined temperature at the nip formed by the fixing roller pair 245. Fixed to the material.

  In the present invention, since the intermediate transfer belt 215 is disposed in a direction inclined to the left in the drawing with respect to the drive roller 213, a wide space is generated on the right side, and the fixing unit 242 can be disposed in the space. The image forming apparatus can be reduced in size, and heat generated by the fixing unit 242 is transferred to the exposure unit 207, the intermediate transfer belt 215, and the single-color image forming units Y, M, C, and K located on the left side. It is possible to prevent adverse effects.

Next, a measurement cell used for work function measurement will be described.
FIG. 4 is a diagram illustrating a sample measurement cell for work function measurement.
As shown in the plan view of FIG. 4 (A) and the side view of FIG. 4 (B), the sample measurement cell C1 accommodates toner having a diameter of 10 mm and a depth of 1 mm in the center of a stainless steel disk having a diameter of 13 mm and a height of 5 mm. It has the shape which has the recessed part C2. After the toner is put into the concave portion of the cell without being tamped using a weighing spoon, the surface is flattened using a knife edge and subjected to measurement.

  After the measurement cell filled with toner is fixed on the specified position of the sample stage, the irradiation light quantity is set to 500 nW, the irradiation area is set to 4 mm square, and the measurement is performed under the conditions of the energy scanning range 4.2 to 6.2 eV. Further, the normalized electron yield at the time of measuring the work function of the toner is 8 or more at a measurement light quantity of 500 nW.

FIG. 5 is a diagram for explaining a method for measuring a work function of a sample having another shape.
When a cylindrical member is used as a sample, such as an intermediate transfer medium or a latent image carrier, the cylindrical member is cut to a width of 1 to 1.5 cm and then cut laterally along the ridgeline. As shown in FIG. 5A, after obtaining the measurement sample piece C3, the measurement light C5 is irradiated on the specified position of the sample stage C4 shown in FIG. 5B. Fix so that the irradiated surface is parallel. Thereby, the emitted photoelectron C6 is efficiently detected by the detector C7, that is, the photoelectron tube.

Examples will be described below.
[Preparation of pulverized toner]:
(Preparation of toner mother particles 1)
80 parts by weight of amorphous polyester, 20 parts by weight of block polyester, 5 parts by weight of magenta pigment Pigment Red 57: 1 as a colorant, and 4 parts by weight of chromium salicylate complex (Bontron E-81) as a charge control agent 3 parts by weight of carnauba wax was prepared as a wax, and these components were mixed using a 20 liter type Henschel mixer to obtain a raw material for toner production.

  Next, this raw material (mixture) is kneaded / cooled using a twin-screw kneading extruder (Toshiba Machine Co., Ltd., TEM-41 type), and the kneaded material is coarsely pulverized (average particle size: 1 to 2 mm). Continue to pulverize. A hammer mill was used for coarse pulverization of the kneaded product, and a jet mill (200 AFG manufactured by Hosokawa Micron Corporation) was used for fine pulverization. The fine pulverization was performed at a pulverization air pressure: 500 [kPa] and a rotor rotation speed: 7000 [rpm]. The pulverized material thus obtained was classified with an airflow diverter (manufactured by Hosokawa Micron Corporation, 100ATP).

As a result, when the obtained magenta toner was measured using FPIA-2100, the average particle size was 7.5 μm on the volume basis, the average particle size was 6.7 μm on the number basis, and the circularity was 0.91. Base particle 1 was designated. The work function of the obtained toner was 5.45 eV when measured with a commercially available surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) with an irradiation light amount of 500 nW.
[Preparation of polymerization toner]:
(Preparation of toner mother particles 2)
A monomer mixture consisting of 80 parts of styrene monomer, 20 parts of butyl acrylate, and 5 parts of acrylic acid, 105 parts by weight of water, 1 part by weight of a nonionic emulsifier (Emulgen 950), 1.5 parts by weight of an anionic emulsifier (Neogen R), and It added to the aqueous solution mixture of 0.55 weight part potassium persulfate, and superposition | polymerization was performed at 70 degreeC under nitrogen stream for 8 hours. After the polymerization reaction, the mixture was cooled to obtain a milky white resin emulsion having a particle size of 0.25 μm.

  Next, 200 parts by weight of this resin emulsion, 20 parts by weight of polyethylene wax emulsion (manufactured by Sanyo Chemical Industries, Ltd., Permarin PN) and 7 parts by weight of carbon black were added with 0.2 parts by weight of sodium dodecylbenzenesulfonate as a surfactant. Disperse in the water, add diethylamine to adjust the pH to 5.5, add 0.3 parts by weight of aluminum sulfate electrolyte while stirring, then emulsify and disperse device (TK machine, TK Homomixer The mixture was stirred at high speed and dispersed.

  Furthermore, 40 parts by weight of styrene monomer, 10 parts by weight of butyl acrylate and 5 parts by weight of zinc salicylate were added together with 40 parts by weight of water, and the mixture was heated to 90 ° C. while stirring under a nitrogen stream, and hydrogen peroxide was added. In addition, polymerization was carried out for 5 hours to grow particles. In order to increase the bond strength of the associating particles after the polymerization was stopped, the temperature was raised to 95 ° C. while adjusting the pH to 5 or more and held for 5 hours. Thereafter, the obtained particles were washed with water and vacuum-dried at 45 ° C. for 10 hours.

As a result, when the obtained black toner was measured using FPIA-2100, the average particle size was 7.8 μm on the volume basis, the average particle size was 7.0 μm on the number basis, and the circularity was 0.97. Base particle 2 was designated. The work function of the obtained toner was 5.52 eV when measured using a commercially available surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) with an irradiation light amount of 500 nW.
[Production of Dissolved Suspension Toner]:
(Preparation of toner mother particles 3)
50:50 (weight ratio) mixture of polycondensation polyester of aromatic dicarboxylic acid and alkylene etherified bisphenol A and a partially crosslinked product of the polymerized polyester with a polyvalent metal compound (manufactured by Sanyo Chemical Industries, Ltd., Himer ES- 803) 100 parts by weight, 5 parts by weight of yellow pigment Pigment Yellow 180, 3 parts by weight of carnauba wax having a melting point of 80 to 86 ° C. as a release agent, and metal salicylic acid complex E-81 (Orient Chemical) as a charge control agent After 4 parts by weight of Kogyo Co., Ltd.) were uniformly mixed using a Henschel mixer, they were kneaded with a twin screw extruder with an internal temperature of 130 ° C. and cooled.

  Next, the cooled product is coarsely pulverized to 2 mm square or less, and 100 parts by weight of this coarsely pulverized product is stirred into a mixed solution of 150 parts by weight of toluene and 100 parts by weight of ethyl acetate, and the oil phase is uniformly mixed and dispersed. Was made.

  Next, 1100 parts by weight of ion-exchanged water and 5 parts by weight of tricalcium phosphate fine powder (preliminarily pulverized with a ball mill and confirmed that no particle size is 3 μm or more) and 1 weight of sodium dodecylbenzenesulfonate A 5% aqueous solution was added and stirred to prepare a uniformly mixed and dispersed solution of the aqueous phase.

  For granulation, first, the above-mentioned aqueous phase dispersion solution is transferred to a container equipped with an ejection portion of porous glass (3 μm pore diameter), a stirring blade and an ultrasonic element as shown in FIG. Next, stirring is continued while the oil phase dispersion solution is press-fitted (from the arrow at the top of the container in FIG. 6) into a pipe directly connected to the ejection portion made of porous glass in the container. The emulsion is formed by dividing particles ejected from the pores of the porous glass by ultrasonic waves. Then, the stirring blade is rotated so that the formed emulsion fine particles do not coalesce. Stirring is continued for 10 minutes after completion of the press-fitting of the oil phase dispersion solution as indicated by the rotating arrows in FIG.

Thereafter, the emulsion formed in the container is removed from the bottom A of the container, and the formed emulsion is transferred. After being transferred to the stirring tank, the temperature is kept at 50 ° C. or higher while stirring in the stirring tank to remove the organic solvent contained therein, followed by washing with 5N normal hydrochloric acid and repeated washing with water and drying. As a result, when the obtained yellow toner was measured using FPIA-2100, the average particle size was 7.2 μm on the volume basis, the average particle size was 6.5 μm on the number basis, and the circularity was 0.98. The mother particle 3 was obtained. The work function of the obtained toner was 5.51 eV when measured with a commercially available surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) with an irradiation light amount of 500 nW.
[Configuration of Developing Roller 1 of Developing Device]
The developing roller of the developing device conducts a conductive EPDM (ethylene propylene rubber, hardness JIS-A, 60 degrees) tube on the central axis surface of an aluminum pipe with a diameter of 18 mm so that the thickness after polishing is 1 mm. A developing roller 1 was prepared by pasting with a conductive adhesive to form a conductive elastic layer (surface roughness Rz: 3 μm).

  A part of the surface layer of the obtained developing roller was cut out to obtain a sample piece, and its work function was measured with a commercially available surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) at an irradiation light amount of 500 nW. 5.55 eV).

The regulating blade is a SUS plate with a thickness of 80 μm, the end is bent at an angle of 10 °, and the protruding length is set to −0.3 mm from the reference point of the normal line, so that the thin layer is regulated. A part of the regulation blade was cut out to obtain a sample piece, and the work function was measured with a commercially available surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) at an irradiation light amount of 10 nW. .42 eV.
[Configuration of Developing Roller 2 of Developing Device]
The developing roller of the developing device is made of a conductive silicone rubber (hardness JIS-A, 63 degrees) tube and conductive adhesive on the central axis of the 18 mm diameter aluminum pipe surface so that the thickness after polishing is 1 mm. Then, a conductive elastic layer was formed (surface roughness Rz: 3 μm), and the developing roller 2 was obtained.

  A part of the surface layer of the obtained developing roller was cut out to obtain a sample piece, and its work function was measured with a commercially available surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) at an irradiation light amount of 500 nW. , 5.08 eV).

The regulating blade is a SUS plate with a thickness of 80 μm, the end is bent at an angle of 10 °, and the protruding length is set to −0.3 mm from the reference point of the normal line, so that the thin layer is regulated. A part of the regulation blade was cut out to obtain a sample piece, and its work function was measured with a commercially available surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) at an irradiation light amount of 10 nW. showed that.
[External additive work function]
Table 1 shows the work function of the external additive used. Each external additive is hydrophobized.

  As shown in Table 1, the work function of the external additive silica is smaller than that of the toner base particles 1, 2, and 3. The work function of the external additive titanium and the metal soap (fine zinc stearate, magnesium stearate, calcium stearate) are the toner. It is almost equivalent to the mother particles 1, 2, and 3. The work function of each external additive was measured using a commercially available surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) at an irradiation light amount of 500 nW.

Next, examples of the present invention will be described in comparison with comparative examples.
In Table 2, the present invention uses the toner base particles 1 to 3 described above, and contains large particle size inorganic fine particles (titanium oxide (200 to 750 nm) in Table 1) and metal soap as an external additive formulation. Is a case where the work function is larger than that of the toner base particles and the negatively charged small particle size silica (negatively chargeable vapor phase silica (12 nm), negatively charged vapor phase silica (40 nm) in Table 1).
In Table 2, the comparative example uses the toner base particles 1 to 3 described above, does not contain large particle size inorganic fine particles or metal soap as an external additive formulation, and the developing roller is a toner base particle, negatively charged small particle size silica. This is a case where the work function is smaller than that of the negatively chargeable gas phase method silica (12 nm, negatively chargeable gas phase method silica (40 nm) in Table 1.).

[Example 1 / Comparative Example 1]
0.8% of hydrophobic silica (work function 5.22 ev) having an average primary particle diameter of about 12 nm as a weight ratio with respect to the base particle 1 (work function 5.45 ev) is about 40 nm. Hydrophobic silica (work function 5.24 ev) of 0.7%, Hydrophobized monodisperse spherical silica (work function 5.01 ev) 0.4%, about 20 nm of hydrophobic titanium oxide (work function) 5.64 ev) 0.5%, negatively charged titanium oxide having a primary particle size in the particle size distribution range of 200 nm to 750 nm, 0.5% (work function 5.41), metal soap (fine stearic acid) A toner containing 0.2% of zinc (work function 5.36 ev) was prepared.

Further, as a comparative toner, a toner not containing negatively charged titanium oxide and metal soap having a primary particle size in a particle size distribution range of 200 nm to 750 nm was also prepared. A continuous printing test was conducted by placing the toner cartridge in the corresponding developing cartridge of the tandem color printer of the photoreceptor cleanerless type shown in FIG. The development is a non-contact development system, the development gap is 200 μm, and the development bias is controlled by patch control so that the amount of development toner per color on the organic photoreceptor (OPC) is suppressed to 0.55 mg / cm ² at maximum. The frequency of the alternating current superimposed on the direct current is 2.5 kHz, the peak-to-peak voltage is 1400 V, and the regulated toner amount on the developing roller is adjusted to be about 0.4 mg / cm ² . The power source of the primary transfer unit is constant voltage control, + 500V is applied, and the power source of the secondary transfer unit is constant current control.

  Then, 10,000 text originals corresponding to a 5% original were continuously printed. After printing was completed, the remaining toner was discharged from the filling port, and the state of toner adhesion to the developing roller was examined. The results are shown in Table 3.

  From Table 3, if a developing roller with a low work function is used, a wiping operation is required after air blowing. However, when a developing roller having a large work function with the toner of Example 1 is used, cleaning is sufficient with only air blowing. It was.

  When the toner of Comparative Example 1 was used, a white substance adhered to the developing roller. When the portion was cut out and the work function was measured, a value of 5.22 eV was shown. This is considered that the silica component in the external additive was adhered.

However, with toners containing amorphous titanium oxide having a particle size distribution of 200 nm to 750 nm and metal soap as external additives, the developing roller can be cleaned only by blowing air, and the development cartridge is not regenerated. It was found that recycling production efficiency was increased. This is considered that not only the external additive is hardly separated from the surface of the toner base particles, but also the polishing effect and spacer effect of the inorganic external additive having a large particle diameter are exhibited at the same time.
[Example 2 & Comparative Example 2]
In Example 2 & Comparative Example 2, the base particles of Example 1 & Comparative Example 1 were changed to base particles 2 (work function 5.52 ev), and inorganic fine particles having a primary particle diameter in the particle size distribution range of 200 nm to 750 nm were negative. The toner was prepared by changing to a chargeable strontium titanate and changing the metal soap to fine magnesium stearate (work function 5.57).

  Further, as a comparative toner, a toner not containing negatively charged strontium titanate and metal soap having a primary particle size in a particle size distribution range of 250 nm to 700 nm was also prepared. A continuous printing test was conducted by placing the toner cartridge in the corresponding developing cartridge of the tandem color printer of the photoreceptor cleanerless type shown in FIG.

  As in the case of Example 1 & Comparative Example 1, 10,000 character originals corresponding to a 5% original were continuously printed. After printing was completed, the remaining toner was discharged from the filling port, and the state of toner adhesion to the developing roller was examined. The results are shown in Table 4.

  From Table 4, if a developing roller with a small work function is used, a wiping operation is required after air blowing. However, when a developing roller with a large work function and the toner of Example 2 is used, cleaning is sufficient with only air blowing. It was.

  When the toner of Comparative Example 2 was used, a white substance adhered to the developing roller. When the portion was cut out and the work function was measured, a value of 5.22 eV was shown. This is considered that the silica component in the external additive was adhered.

However, in the case of toner containing amorphous strontium titanate having a particle size distribution of 250 nm to 700 nm and metal soap as an external additive, the developing roller can be cleaned only by blowing air, and it takes time to regenerate the developing cartridge. It was found that recycling efficiency was high. This is considered that not only the external additive is hardly separated from the surface of the toner base particles, but also the polishing effect and spacer effect of the inorganic external additive having a large particle diameter are exhibited at the same time.
[Example 3 & Comparative Example 3]
0.8% of hydrophobic silica (work function 5.22 ev) having an average primary particle size of about 12 nm in weight ratio to the base particle 3 (work function 5.51 ev) is about 40 nm. Hydrophobic silica (work function 5.24 ev) of 0.7%, Hydrophobized monodisperse spherical silica (work function 5.01 ev) 0.4%, about 20 nm of hydrophobic titanium oxide (work function) 5.64 ev) 0.5%, negatively charged titanium oxide having a primary particle size in the particle size distribution range of 200 nm to 750 nm, 0.5% (work function 5.41), metal soap (calcium stearate ( A toner containing 0.1% work function 5.49ev)) and 0.35% toner were prepared.
Further, as a comparative toner, a toner not containing negatively charged titanium oxide and metal soap having a primary particle size in a particle size distribution range of 200 nm to 750 nm was also prepared.
A continuous printing test was conducted by placing the toner cartridge in the corresponding developing cartridge of the tandem color printer of the photoreceptor cleanerless type shown in FIG.

  As in the case of Example 1 & Comparative Example 1, 10,000 character originals corresponding to a 5% original were continuously printed. After printing was completed, the remaining toner was discharged from the filling port, and the state of toner adhesion to the developing roller was examined. The results are shown in Table 5.

  From Table 5, if a developing roller having a small work function is used, a wiping operation is necessary after air blowing. However, when the developing roller having a large work function and the toner of Example 3 is used, cleaning with air blowing is sufficient. .

However, when filming on the developing roller after continuous printing was examined, when the content of metal soap was 0.1%, it was in the range of 0.003 to 0.006 mg / cm ^2. At 0.35%, the filming amount tended to slightly increase, and the polishing effect of the large particle size inorganic external additive tended to decrease. Therefore, it was judged that the upper limit of the metal soap content is preferably 0.3% or less.

  According to the present invention, it is possible to prevent toner and external additives from adhering to the developing roller of the developing device, and cleaning can be easily performed when the used developing cartridge is regenerated.

It is a figure explaining the example of the developing device to which this invention is applied. It is a figure explaining a stirring member. It is a figure explaining the example of the cleanerless color image forming apparatus carrying the developing device of FIG. It is a figure explaining the sample measurement cell for work function measurement. It is a figure explaining the measuring method of the work function of the sample of another shape. It is a figure explaining the granulation method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 17 ... Photoconductor, 20 ... Developing apparatus main body, 26 ... Toner storage container, 27 ... Toner container, 29 ... Toner stirring member, 29a ... Conveying member, 30 ... Toner receiving member, 30a ... Scraper, 31 ... Supply roller, 32 ... Receiving sheet, 33 ... Developing roller, 34 ... Regulating blade, 45 ... Case wall, 46 ... Upper seal.

Claims (6)

A first external additive comprising inorganic fine particles having a primary particle size particle size distribution of 200 to 750 nm and having a work function substantially equal to that of the toner base particles, an average particle size smaller than that of the first external additive, and A toner containing toner mother particles and a second external additive composed of inorganic fine particles having a work function smaller than that of a developing roller of a developing device;
A toner comprising 0.01% to 0.3% by weight of a metal soap having a work function substantially equal to that of toner base particles. The toner according to claim 1, wherein the inorganic fine particles are subjected to a hydrophobic treatment, and the toner is a nonmagnetic one-component negatively chargeable toner. 2. The toner according to claim 1, wherein the work function of the developing roller of the developing device is equal to or higher than the work function of the toner base particles. An image forming apparatus comprising a developing device for developing using the toner according to claim 1. 5. The image forming apparatus according to claim 4, further comprising: a developing device having a stirring member that retains the toner regulated by the regulation unit in the primary storage unit and then transports the toner to the regulation unit through the secondary storage unit. apparatus. 6. The image forming and developing apparatus according to claim 4, wherein the work function of the developing roller of the developing apparatus is equal to or higher than the work function of the toner base particles.

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