JP2007114368A - Cleaning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent faulty cleaning by effectively removing paper powder and residual toner remaining on a surface of an image carrier without transferring to a transfer member (recording medium or intermediate transfer member) while preventing a lubricant from being excessively applied on the surface of the image carrier. <P>SOLUTION: The cleaning device is provided which removes toner remaining on an image carrier after transfer without transferring to a transfer member, wherein a main cleaning member for removing residual toner is a blade, brush rollers are disposed on upstream and downstream sides of the cleaning blade in a transport direction of the image carrier, and the cleaning capability (scraping amount) of the upstream brush roller is smaller than that of the downstream brush roller. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a fax machine, or a multifunction machine having these functions, in particular, an image forming apparatus using an intermediate transfer member, and a cleaning device mounted on the image forming apparatus.

Japanese Patent Application Laid-Open No. 08-320643 JP 2000-338819 A JP 2002-55580 A JP 2002-244487 A

  An image forming apparatus using an electrophotographic process includes a photoconductor as an image carrier, charges the surface of the photoconductor to be charged, exposes the charged photoconductor surface to form an electrostatic latent image, and A toner is supplied to the electrostatic latent image to make it visible, and the visible image formed on the surface of the photoreceptor is transferred to the surface of the recording medium and fixed (in some cases after primary transfer to the intermediate transfer member in advance). To discharge. Since the untransferred toner and the like remain on the surface of the image bearing member of the photosensitive member or intermediate transfer member after the transfer of the visible image, the surface of the photosensitive member or the intermediate transferring member does not adversely affect the next image formation. Is cleaned by a cleaning device to prepare for the next image forming process. In a configuration generally known as such a cleaning device, an image carrier is provided with a cleaning roller in which untransferred toner is physically scraped off by a cleaning blade made of an elastic material such as rubber, or a synthetic resin fiber is formed in a brush shape. The surface is rubbed to remove deposits such as untransferred toner.

  However, the cleaning blade and the cleaning brush as described above have a problem that if they are continuously rubbed with the image carrier, they are gradually worn and the cleaning performance is deteriorated due to chipping or deformation. Further, since the surface of the image carrier is also worn, the life is shortened. Therefore, in order to reduce the frictional resistance acting between the image carrier and these cleaning members and eliminate problems such as abrasion of the cleaning member and the image carrier, lubricant is applied to the image through the application roller and the brush roller. Many proposals for applying to a carrier have been disclosed (see, for example, Patent Documents 1, 2, 3, and 4).

  Incidentally, in recent years, there has been an increasing demand for higher image quality, and in order to realize particularly high-definition color image formation, the toner has been reduced in particle size and spheroidized. The reproducibility of dots is improved by reducing the particle size, and the developability and transferability can be improved by making the particles spherical. Since it is very difficult to produce such a small particle size and spherical toner by the conventional kneading and pulverization method, the polymerization produced by suspension polymerization method, emulsion polymerization method, dispersion polymerization method, etc. Toner is being adopted. However, when a toner having a spherical shape and a reduced particle size is used, cleaning on the belt-shaped image carrier performed after image formation has become increasingly difficult.

  In the SPR-C toner, which is one of the polymerized toners, since the wax component is uniformly dispersed inside the toner, there is little precipitation of the wax component outside when adhering to the image carrier, and the surface of the image carrier There is a tendency that the coefficient of friction μs increases with time. Therefore, it is necessary to apply a lubricant in order to prevent blade entrainment and surface filming.

  However, when applying the lubricant on the image carrier, if the lubricant is applied with the residual toner attached to the surface of the image carrier, it is difficult to uniformly apply the lubricant to the surface of the image carrier. When the tip of the cleaning blade hits a portion where the surface lubricant is not applied, there is a problem that it is difficult to prevent defective cleaning due to vibration of the tip of the blade due to a change in frictional force. Further, when a lubricant more than a necessary amount is applied to the image carrier, the charging performance of the charging member is reduced due to image flow or contamination of the charging member by the lubricant.

  In view of the above circumstances, the present invention prevents the lubricant from being excessively applied to the surface of the image carrier, and does not transfer to the transfer member (recording medium or intermediate transfer member). It is an object to effectively remove residual toner and paper dust remaining on the surface and prevent occurrence of defective cleaning.

  According to the present invention, the object is to provide a cleaning device for cleaning the toner remaining on the image carrier without being transferred to the transfer body after the transfer process, wherein the main cleaning member for cleaning the residual toner is constituted by a blade, This is achieved by providing brush rollers on the upstream and downstream sides of the cleaning blade in the image carrier conveying direction, respectively, and the cleaning ability (scraping amount) of the upstream brush roller is smaller than that of the downstream brush roller.

  The downstream brush roller is intended for lubricant application to the transfer body, and the length orthogonal to the transfer body conveyance direction is preferably equal to or greater than the effective width of the cleaning blade. The effective width of the blade means a width corresponding to the planned maximum image width in the transfer body to be cleaned.

  It is effective that the upstream brush roller includes an attached foreign matter removing member. The flocking range in the direction orthogonal to the transfer body conveyance direction of the upstream brush roller is preferably narrower than the flocking range of the downstream brush roller. The length of the upstream brush roller in the direction perpendicular to the transfer body conveyance direction is preferably shorter than the width of the cleaning blade. It is also convenient that the length of the upstream brush roller in the direction orthogonal to the transfer body conveyance direction is at least equal to or greater than the width of the minimum paper size to be passed and less than the effective image width. The length of the adhered foreign matter removing member in the direction orthogonal to the transfer body conveyance direction is preferably shorter than the length of the upstream brush roller. It is also preferable that the length of the adhered foreign matter removing member in the direction orthogonal to the transfer body conveyance direction is at least equal to or larger than the width of the minimum paper size to be passed and less than the effective image width.

  When a toner having a volume average particle diameter of 3 to 8 μm and a ratio (dispersity) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) in the range of 1.00 to 1.40 is used. The present invention becomes more effective. The present invention is more advantageous when using toner having a toner shape factor SF-1 in the range of 100 to 180 and a toner shape factor SF-2 in the range of 100 to 180. The toner used has a substantially spherical appearance, and the ratio of the minor axis to the major axis (r2 / r1) is in the range of 0.5 to 1.0, and the ratio of the thickness to the minor axis (r3 / r2) is in the range of 0.7 to 1.0, and the relationship of major axis r1 ≧ minor axis r2 ≧ thickness r3 is satisfied. In the toner, a toner material liquid in which a toner composition containing at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent is crosslinked in an aqueous medium. It is preferable that the toner is obtained by an extension reaction.

  According to the present invention, the main cleaning member for cleaning the residual toner is constituted by the blade, and the brush roller is provided on the upstream side and the downstream side in the image carrier conveying direction of the cleaning blade, respectively. Since (scraping amount) is smaller than that of the downstream brush roller, both stable application of lubricant and paper dust removal are possible.

  The length of the upstream brush roller in the direction perpendicular to the transfer body conveyance direction is shorter than the width of the cleaning blade, which ensures that the lubricant reaches the end of the blade and improves the blade winding margin. To do. If the length of the upstream brush roller in the direction perpendicular to the transfer direction of the transfer body is at least the width of the minimum paper size to be passed and less than the effective image width, the original purpose of removing paper dust Almost no ability reduced. The length of the adhering foreign matter removing member (flicker) in the direction perpendicular to the transfer body conveyance direction is shorter than the length of the upstream brush roller, or the length of the adhering foreign matter removal member in the direction perpendicular to the transfer body conveyance direction. However, if it is at least the width of the minimum paper size to be passed and less than the effective image width, the scraping ability at the end of the upstream brush roller is reduced, and the lubricant is surely applied to the blade end. Reach.

  An image forming apparatus according to an exemplary configuration of the present invention will be described with reference to FIG. Although this image forming apparatus is a tandem type indirect transfer type copying machine, the present invention can also be applied to a revolver type image forming apparatus, and in the following, cleaning to an intermediate transfer member will be described. As a matter of course, a photosensitive belt can also be used as an image carrier.

  An endless belt-like intermediate transfer member 11 is provided in the central region of the apparatus main body. The intermediate transfer body 11 has a multi-layer structure, and the base layer is made of, for example, a fluorine resin, PVD sheet, or polyimide resin that has little elongation, and the surface is covered with a smooth coating layer such as a fluorine resin. Yes. Then, in the illustrated example, it is wound around the support rollers 10, 12, 34, and 35 so as to be able to rotate and convey counterclockwise in the drawing.

  In this illustrated example, an intermediate transfer body cleaning device 25 for removing residual toner remaining on the intermediate transfer body 11 after image transfer is provided further to the left of the support roller 10 at the left end in the drawing. The cleaning counter roller 10 also serves as a tension roller in this example.

  Further, on the lower side of the intermediate transfer body 11 stretched between the support roller 12 and the support roller 35, four image forming units of black, yellow, magenta, and cyan are arranged side by side along the conveyance direction. A tandem image forming apparatus is configured. An exposure device 4 is further provided below the tandem image forming apparatus.

  On the other hand, a secondary transfer device is provided on the side opposite to the right support roller 35 of the intermediate transfer body 11. In the illustrated example, the secondary transfer device is configured by spanning a secondary transfer belt 100, which is an endless belt, between two rollers 111 and 112, and is pressed against the support roller 35 via the intermediate transfer body 11. Then, the image on the intermediate transfer body 11 is transferred to a sheet. Some secondary transfer devices use secondary transfer rollers, as shown in FIG. Since FIG. 2 has the same configuration as that of FIG. 1 except for the secondary transfer roller 36, description thereof is omitted.

  A fixing device 30 for fixing the transferred image on the sheet is provided above the secondary transfer device. The fixing device 30 is configured by pressing a pressure roller against the fixing roller. The secondary transfer device described above is also provided with a sheet transport function for transporting the image-transferred sheet to the fixing device 30. Of course, it is assumed that a non-contact charger is arranged as the secondary transfer device, but in such a case, the sheet conveying function is performed separately by another configuration.

  When a start switch (not shown) is pressed, one of the support rollers 10, 34, 35 (for example, 34) is rotationally driven by a drive motor (not shown) to stabilize the other three support rollers (these stabilize the primary transfer nip). The intermediate transfer body 11 is rotated and conveyed. At the same time, the photosensitive member 1 is rotated by individual image forming means, and the primary transfer roller 20 forms monochrome images of black, yellow, magenta, and cyan on the photosensitive member 1, respectively. The configuration of each image forming unit is well known and will not be further described. Then, along with the conveyance of the intermediate transfer body 11, the single color images are sequentially transferred to form a composite color image on the intermediate transfer body 11.

  On the other hand, when a start switch (not shown) is pressed, the sheet P is fed out by selective rotation of the paper feed roller 27 from one of the paper feed tables 26 provided in multiple stages in a paper bank provided further below the exposure device 4. Then, the paper is separated one by one by a separation roller (not shown), put into the paper feed path 29, and abutted against the registration roller 28 and stopped. Then, the registration roller 28 is rotated in synchronization with the composite color image on the intermediate transfer body 11, the sheet is fed between the intermediate transfer body 11 and the secondary transfer device, and is transferred by the secondary transfer device to be transferred onto the sheet. Record a color image on

  The image-transferred sheet is conveyed by the secondary transfer belt 100 and fed to the fixing device 30. The fixing device 30 applies heat and pressure to fix the transferred image, and is then discharged by the discharge roller 32 and discharged. Stack on the paper tray 40.

  On the other hand, the intermediate transfer body 11 after the image transfer is removed by the intermediate transfer body cleaning device 25 to remove residual toner remaining on the intermediate transfer body 11 after the image transfer, and is prepared for re-image formation by the tandem image forming apparatus.

  In this example, it is assumed that the intermediate transfer member cleaning device 25 has a plurality of brush rollers. FIG. 3 shows a detailed configuration of the intermediate transfer member cleaning 25. In the SPR-C toner, which is one of the polymerized toners, the wax component is uniformly dispersed inside the toner. Therefore, when the toner adheres to the intermediate transfer belt, there is little precipitation of the wax component on the surface of the intermediate transfer belt. There is a tendency that the friction coefficient μs increases with time. Therefore, it is necessary to apply a lubricant to prevent blade entrainment and surface filming. Therefore, at least one of the plurality of brush rollers is used for the purpose of lubricant application (brush roller 44 on the downstream side of the blade).

  In the cleaning device having the blade cleaning blade 41, the application of the lubricant on the downstream side in the belt conveying direction of the cleaning blade is not affected by the residual toner, so that it can be stably applied (blade width of the blade). It is necessary to apply uniformly within the range). On the other hand, a member for removing paper dust or the like is necessary on the upstream side of the cleaning blade in the belt conveyance direction. In particular, a toner having a small particle size and high circularity, such as SPR-C toner, is easy to slip through the blade, so that the paper powder also slips through the blade together with the toner and the paper powder is likely to be caught. When a fixed brush or moquette is used as the paper dust removing member, if the paper dust removing member itself becomes dirty, the removal capability is lowered. Therefore, it is not suitable for a case where the amount of paper dust input is large or a device aiming for a long life. Therefore, a brush roller is used as the paper dust removing member. Then, foreign matters such as paper dust attached to the paper dust removing brush roller 42 are removed by being removed from the brush roller by a foreign matter removing member (flicker 43) in which the fixing member is bitten into the brush roller.

  By the way, since the paper dust removing brush roller 42 on the upstream side of the blade removes toner and lubricant together with the paper dust, if the cleaning ability (scraping ability) of the brush roller 42 on the upstream side of the blade is too high, the blade Since the lubricant applied on the downstream side does not reach the required amount to the blade 41, there is a concern that the blade will be caught. Therefore, the scraping ability of the brush roller 42 on the upstream side of the blade is made smaller than that of the brush roller 44 for applying lubricant on the downstream side of the blade.

  In addition, blade entrainment is severe when small-size paper is passed in which the input toner and paper dust at the blade end are reduced. In view of this, two methods have been devised in which the scraping ability at the end of the brush roller 42 on the upstream side of the blade (outside the sheet passing size) is reduced and the lubricant is input to the end of the blade.

  First, as shown in FIG. 4, the length of the upstream brush roller 42 is made smaller than that of the blade 41 so that the lubricant sufficiently reaches the end of the blade when passing small-size paper. Paper dust is generated particularly in the paper feed roller section, and the paper feed roller is within the minimum paper size width to pass the paper, so the upstream brush roller width is longer than the minimum paper size width and smaller than the effective image width. If so, the effect of removing paper dust is hardly reduced.

  The other is, as shown in FIG. 5, the length of the foreign matter removing member (flicker 43) of the upstream brush roller 42 is shorter than that of the brush roller 42, and the toner or lubricant adhering to the end of the brush roller 42. By saturating, the scraping ability at the edge was reduced. Regarding the flicker length, if the length is larger than the minimum paper size width and smaller than the effective image width, the effect of removing paper dust is hardly reduced.

  In the image forming apparatus according to the present invention, the toner used has a volume average particle diameter of 3 to 8 μm to reproduce minute dots of 600 dpi or more, and the volume average particle diameter (Dv) and the number average particle diameter ( The ratio of Dn) (Dv / Dn: dispersity) is preferably in the range of 1.00 to 1.40. The closer the dispersity is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method increases the transfer rate. be able to. The average particle size and particle size distribution of the toner can be measured using a Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). In the present invention, a Coulter counter TA-II type was used and connected to an interface (manufactured by Nikka Giken) and a personal computer (PC9801: manufactured by NEC) for outputting the number distribution and volume distribution.

The toner used preferably has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. FIG. 6 schematically shows the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2. The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting toner on a two-dimensional plane by the graphic area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) Expression (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.

The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). This is a value obtained by dividing the square of the peripheral length PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100 / 4π.
SF-2 = {(PERI) ² / AREA} × (100 / 4π) (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.

  When the shape of the toner is close to a sphere, the contact between the toner and the toner, or the contact between the toner and the image carrier is close to a point contact. The attracting force with the image carrier is also weakened, and the transfer rate is increased. On the other hand, since spherical toner tends to enter the gap between the cleaning blade and the photosensitive member, the toner shape factor SF-1 or SF-2 is preferably large to some extent. Further, when SF-1 and SF-2 are increased, toner is scattered on the image and the image quality is lowered. For this reason, SF-1 and SF-2 preferably do not exceed 180. Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.) and introducing it into an image analyzer (LUSEX3: manufactured by Nireco) for analysis. And calculated.

  The toner suitably used is, for example, a method in which a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent is dispersed in an organic solvent is crosslinked in an aqueous solvent. A toner obtained by an extension reaction. Hereinafter, description will be given with examples of toner constituent materials and manufacturing methods.

polyester:
The toner contains polyester as a binder resin. The polyester is obtained by a polycondensation reaction between a polyhydric alcohol compound and a polycarboxylic acid compound. Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO), and DIO alone or a mixture of DIO and a small amount of TO is preferable. Dihydric alcohol (DIO) includes alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts. Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. As trihydric or higher polyhydric alcohol (TO), 3 to 8 or higher polyhydric aliphatic alcohol (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

  Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC), and DIC alone or a mixture of DIC and a small amount of TC is preferable. Divalent carboxylic acids (DIC) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid) , Naphthalenedicarboxylic acid, etc.). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polyvalent carboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polycarboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

  The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.

  The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.

  The polycondensation reaction between a polyhydric alcohol (PO) and a polycarboxylic acid (PC) is carried out in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and heated to 150 to 280 ° C. while reducing the pressure as necessary. The produced water is distilled off to obtain a polyester having a hydroxyl group. The hydroxyl value of the polyester is preferably 5 or more, and the acid value of the polyester is usually 1 to 30, preferably 5 to 20. By giving an acid value, it tends to be negatively charged, and furthermore, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixability is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation.

  The weight average molecular weight is 10,000 to 400,000, preferably 20,000 to 200,000. A weight average molecular weight of less than 10,000 is not preferable because offset resistance deteriorates. On the other hand, if it exceeds 400,000, the low-temperature fixability is deteriorated.

  In addition to the unmodified polyester obtained by the above polycondensation reaction, the polyester preferably contains a urea-modified polyester. The urea-modified polyester is obtained by reacting a terminal carboxyl group or hydroxyl group of the polyester obtained by the above polycondensation reaction with a polyvalent isocyanate compound (PIC) to obtain a polyester prepolymer (A) having an isocyanate group. It is obtained by cross-linking and / or extending the molecular chain by the reaction of the amine with amines.

  Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) ); Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; phenol derivatives, oximes, polyisocyanates; Those blocked with caprolactam and the like; and combinations of two or more of these.

  The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably 4 as the equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. / 1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.

  The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer having an isocyanate group is usually 0.5 to 40 wt%, preferably 1 to 30 wt%, more preferably 2 to 20 wt%. If it is less than 0.5 wt%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40 wt%, the low-temperature fixability deteriorates.

  The number of isocyanate groups contained per molecule in the polyester prepolymer having isocyanate groups is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2.5 on average. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.

  Next, as the amines to be reacted with the polyester prepolymer, a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4), an amino acid (B5) And those in which the amino groups of B1 to B5 are blocked (B6).

  Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like. Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the B1 to B5 amino group blocked (B6) include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines, preferred are a divalent amine compound and a mixture of a divalent amine compound and a small amount of a divalent or higher polyvalent amine compound.

  The ratio of amines is usually 1/2 to 2/2 / as the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer having isocyanate groups and amino groups [NHx] in amines. 1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] is more than 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated.

  The urea-modified polyester may contain a urethane bond as well as a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.

  The modified polyester is produced by a one-shot method or the like. Polyhydric alcohol (PO) and polyvalent carboxylic acid (PC) are heated to 150-280 ° C. in the presence of a known esterification catalyst such as tetrabutoxytitanate, dibutyltin oxide, etc., and water generated while reducing the pressure as necessary. Distill off to obtain a polyester having a hydroxyl group. Subsequently, at 40-140 degreeC, this is made to react with polyvalent isocyanate (PIC), and the polyester prepolymer (A) which has an isocyanate group is obtained. Furthermore, this ester prepolymer is reacted with amines (B) at 0 to 140 ° C. to obtain a urea-modified polyester.

  When reacting polyvalent isocyanate (PIC) and when reacting the ester prepolymer and amines, a solvent can be used if necessary. Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers And those inert to isocyanates (PIC), such as tetrahydrofuran (such as tetrahydrofuran).

  In addition, in the crosslinking and / or extension reaction between the polyester prepolymer and amines, a reaction terminator can be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).

  The weight average molecular weight of the modified polyester is usually 10,000 or more, preferably 20,000 to 10,000,000, more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance deteriorates. The number average molecular weight of the urea-modified polyester is not particularly limited when the above-mentioned unmodified polyester is used, and may be a number average molecular weight that can be easily obtained to obtain the above weight average molecular weight. When the urea-modified polyester is used alone, its number average molecular weight is usually 2000-15000, preferably 2000-10000, more preferably 2000-8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color apparatus are deteriorated.

  By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the glossiness when used in a full-color image forming apparatus are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond.

  The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition.

  The weight ratio of unmodified polyester to urea-modified polyester is usually 20/80 to 95/5, preferably 70/30 to 95/5, more preferably 75/25 to 95/5, and particularly preferably 80 /. 20-93 / 7. When the weight ratio of the urea-modified polyester is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

  The glass transition point (Tg) of the binder resin containing unmodified polyester and urea-modified polyester is usually 45 to 65 ° C, preferably 45 to 60 ° C. If it is less than 45 ° C., the heat resistance of the toner deteriorates, and if it exceeds 65 ° C., the low-temperature fixability becomes insufficient.

  In addition, since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the heat-resistant storage stability tends to be good even when the glass transition point is low as compared with known polyester-based toners.

Colorant:
As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher, yellow Lead, Titanium Yellow, Polyazo Yellow, Oil Yellow, Hansa Yellow (GR, A, RN, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R) , Tartrazine rake, quinoline yellow rake, anthrazan yellow BGL, isoindolinone yellow, bengara, red lead, lead vermilion, cadmium red, cadmium mercurial red, antimon vermilion, permanent red 4R, para red, phissa red, parachlor ortho Nitroa Lynn Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carnmin BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R , Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Po Azo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalo Anine green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The content of the colorant is usually 1 to 15% by weight, preferably 3 to 10% by weight, based on the toner.

  The colorant can also be used as a master batch combined with a resin. Binder resin kneaded with the masterbatch production or masterbatch includes styrene, such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene, etc., and substituted polymers thereof, or copolymers of these with vinyl compounds. , Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, Aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffin, paraffin wax and the like can be mentioned, and these can be used alone or in combination.

Charge control agent:
Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Industries, Ltd.), quaternary ammonium salt copy Charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge NEG VP2036 of quaternary ammonium salt, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo pigments, other pigments Acid group, carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.

  The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the flowability of the developer is lowered, and the image density is lowered. Invite.

Release agent:
As a release agent, a low melting point wax having a melting point of 50 to 120 ° C. works more effectively as a release agent between the fixing roller and the toner interface in the dispersion with the binder resin. It exhibits an effect on high temperature offset without applying a release agent such as oil. Examples of such a wax component include the following. Examples of waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax, rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline, and petrolatum. And petroleum wax. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can be used. Further, fatty acid amides such as 12-hydroxystearic amide, stearic amide, phthalic anhydride, chlorinated hydrocarbons, and low molecular weight crystalline polymer resins such as poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be used. . The charge control agent and the release agent can be melt-kneaded together with the master batch and the binder resin, or may be added when dissolved and dispersed in the organic solvent.

External additives:
Inorganic fine particles are preferably used as an external additive for assisting the fluidity, developability and chargeability of the toner particles. The primary particle diameter of the inorganic fine particles is preferably 5 × ¹⁰ -3 ~2μm, it is particularly preferably 5 × ¹⁰ -3 ~0.5μm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m < ² > / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5 wt% of the toner, and particularly preferably 0.01 to 2.0 wt%.

Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Among these, as the fluidity imparting agent, it is preferable to use hydrophobic silica fine particles and hydrophobic titanium oxide fine particles in combination. In particular, when stirring and mixing are performed using particles having an average particle diameter of 5 × 10 ⁻² μm or less, the electrostatic force and van der Waals force with the toner are remarkably improved. Even when stirring and mixing inside the developing device is performed to obtain a good image quality that does not cause release of the fluidity imparting agent from the toner and does not generate firefly, etc., and further reduces the residual toner. It is done.

  Titanium oxide fine particles are excellent in environmental stability and image density stability, but tend to deteriorate the charge rise characteristics. Therefore, if the amount of titanium oxide fine particles added is greater than the amount of silica fine particles added, the effect of this side effect Is considered to be large. However, when the addition amount of the hydrophobic silica fine particles and the hydrophobic titanium oxide fine particles is in the range of 0.3 to 1.5 wt%, the charge rising characteristics are not greatly impaired, and the desired charge rising characteristics can be obtained, that is, repeated copying. Stable image quality can be obtained even if

Next, a toner manufacturing method will be described. Here, although a preferable manufacturing method is shown, it is not limited to this.
1) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent. The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are preferred. The usage-amount of an organic solvent is 0-300 weight part normally with respect to 100 weight part of polyester prepolymers, Preferably it is 0-100 weight part, More preferably, it is 25-70 weight part.

  2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles. The aqueous medium may be water alone or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be included.

The amount of the aqueous medium used relative to 100 parts by weight of the toner material liquid is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical.
Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.

  As surfactants, alkylbenzene sulfonates, α-olefin sulfonates, anionic surfactants such as phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, benzethonium chloride, fatty acid amide derivatives, polyhydric alcohols Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine.

  Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkyl carboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-hydroxyethyl) perfluoroocta Sulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. .

  Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (Daikin Kogyo Co., Ltd.), Mega-Fac F-110, F-120, F-113, F-191, F-812, F-833 (Dainippon Ink Co., Ltd.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F-150 (manufactured by Neos).

  In addition, as the cationic surfactant, aliphatic quaternary ammonium salts such as aliphatic primary, secondary or secondary amic acid and perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt that right the fluoroalkyl group are used. Benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (Asahi Glass Co., Ltd.), Florard FC-135 (Sumitomo 3M Co., Ltd.), Unidyne DS-202 (Daikin Industries) Manufactured), MegaFuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footgent F-300 (Neos), and the like.

  The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10 to 90%. For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao), SGP (manufactured by Soken Co., Ltd.), Technopolymer SB (Manufactured by Sekisui Plastics Co., Ltd.), SGP-3G (manufactured by Sokensha), micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.) and the like.

In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.
As a dispersant that can be used in combination with the above resin fine particles and inorganic compound dispersant, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomer Bodies such as acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxy Propyl, acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate , N-methylol Rilamide, N-methylolmethacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc., or esters of vinyl alcohol and compounds containing a carboxyl group, such as vinyl acetate , Vinyl propionate, vinyl butyrate, etc., acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl imidazole, ethyleneimine, etc. Homopolymers or copolymers such as nitrogen compounds or those having heterocycles thereof, polyoxyethylene, polyoxypropylene, polyoxyethylene alkyl Poly, such as amine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonyl phenyl ester Celluloses such as oxyethylene, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and the like can be used.

  The dispersion method is not particularly limited, and known equipment such as a low-speed shear type, a high-speed shear type, a friction type, a high-pressure jet type, and an ultrasonic wave can be applied. Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 to 20 μm. When a high-speed shearing disperser is used, the rotation speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but is usually 0.1 to 5 minutes in the case of a batch method. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C.

  3) At the same time as the preparation of the emulsion, the above-described amines are added to cause a reaction with the polyester prepolymer having an isocyanate group. This reaction involves molecular chain crosslinking and / or elongation. Although reaction time is selected by the reactivity of the isocyanate group structure and amines which a polyester prepolymer has, it is 10 minutes-40 hours normally, Preferably it is 2-24 hours. The reaction temperature is usually 0 to 150 ° C., preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

  4) After completion of the reaction, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles. In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after giving strong stirring in a certain temperature range, the solvent base is removed to produce spindle-shaped toner base particles. . Further, when an acid such as calcium phosphate salt or an alkali-soluble material is used as the dispersion stabilizer, the calcium phosphate salt is dissolved from the toner base particles by a method such as washing with water after dissolving the calcium phosphate salt with an acid such as hydrochloric acid. Remove. In addition, it can be removed by an operation such as enzymatic degradation.

  5) A charge control agent is injected into the toner base particles obtained above, and then inorganic fine particles such as silica fine particles and titanium oxide fine particles are externally added to obtain a toner. The injection of the charge control agent and the external addition of the inorganic fine particles are performed by a known method using a mixer or the like. Thereby, a toner having a small particle size and a sharp particle size distribution can be easily obtained. Furthermore, by applying strong agitation in the process of removing the organic solvent, the shape between the spherical shape and the rugby ball shape can be controlled, and the surface morphology is also controlled between the smooth shape and the umeboshi shape. be able to.

  Further, the toner has a substantially spherical shape and can be expressed by the following shape rule. FIG. 7 is a diagram schematically showing the shape of the toner. In FIG. 7, when a substantially spherical toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), the toner has a ratio of the major axis to the minor axis (r2). / R1) (see FIG. 7B) is 0.5 to 1.0, and the ratio of thickness to short axis (r3 / r2) (see FIG. 7C) is 0.7 to 1.0. It is preferable to be in the range. When the ratio of the major axis to the minor axis (r2 / r1) is less than 0.5, the dot reproducibility and transfer efficiency are inferior because of being away from the true spherical shape, and high-quality image quality cannot be obtained. On the other hand, if the ratio of thickness to minor axis (r3 / r2) is less than 0.7, the shape is close to a flat shape, and a high transfer rate like a spherical toner cannot be obtained. In particular, when the ratio of the thickness to the minor axis (r3 / r2) is 1.0, the rotating body has a major axis as a rotation axis, and the fluidity of the toner can be improved. Note that r1, r2, and r3 were measured with a scanning electron microscope (SEM) while changing the angle of field of view and taking pictures.

1 is a schematic configuration diagram of an image forming apparatus according to the present invention. It is a schematic block diagram of an intermediate transfer unit when the secondary transfer means is a roller. It is a structure sectional view of the cleaning device concerning the present invention. It is a figure which shows the relationship of each length of an upstream brush roller, a cleaning blade, and a downstream brush roller. It is a figure which shows the relationship of each length of an upstream brush roller, an attached foreign material removal member, and a cleaning blade. FIG. 6 is a toner shape schematic diagram for explaining shape factors SF-1 and SF-2. It is a figure which shows a toner shape typically.

Explanation of symbols

41 Cleaning blade 42 Upstream brush roller 43 Flicker 44 Downstream brush roller

Claims (14)

A cleaning device for cleaning toner remaining on the image carrier without being transferred to the transfer body after the transfer process, and a main cleaning member for cleaning the residual toner is constituted by a blade,
Brush rollers are respectively provided on the upstream side and the downstream side of the image carrier conveying direction of the cleaning blade,
A cleaning device characterized in that the upstream brush roller has a cleaning capability (scraping amount) smaller than that of the downstream brush roller.   The downstream brush roller is intended for lubricant application to a transfer body, and the length orthogonal to the transfer body conveyance direction is equal to or greater than the effective width of the cleaning blade. Cleaning device.   The cleaning device according to claim 1, wherein the upstream brush roller includes an attached foreign matter removing member.   The cleaning apparatus according to claim 1, wherein a flocking range in a direction orthogonal to the transfer body conveyance direction of the upstream brush roller is narrower than a flocking range of the downstream brush roller.   5. The cleaning device according to claim 1, wherein a length of the upstream brush roller in a direction orthogonal to the transfer body conveyance direction is shorter than a width of the cleaning blade.   6. The length of the upstream brush roller in a direction perpendicular to the transfer body conveyance direction is at least equal to or larger than the width of the minimum paper size to be passed and less than the effective image width. Cleaning device.   The cleaning apparatus according to claim 3, wherein a length of the attached foreign matter removing member in a direction perpendicular to the transfer body conveyance direction is shorter than a length of the upstream brush roller.   8. The length of the attached foreign matter removing member in a direction perpendicular to the transfer body conveyance direction is at least equal to or larger than the width of the minimum paper size scheduled to be passed and less than the effective image width. Cleaning device.   An image forming apparatus comprising the cleaning device according to claim 1.   11. A toner having a volume average particle diameter of 3 to 8 [mu] m and a ratio of the volume average particle diameter to the number average particle diameter (dispersion degree) in the range of 1.00 to 1.40. The image forming apparatus described in 1.   11. The image forming apparatus according to claim 10, wherein a toner having a toner shape factor SF-1 in the range of 100 to 180 and a toner shape factor SF-2 in the range of 100 to 180 is used.   The toner to be used is a cross-linking of a toner material liquid in which a toner composition containing at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent in an organic solvent is dispersed in an aqueous medium. The image forming apparatus according to claim 9, wherein the toner is obtained by an extension reaction.   The image forming apparatus according to claim 9, wherein the toner used has a substantially spherical appearance.   The shape of the toner used is defined by the major axis r1, the minor axis r2, and the thickness r3, and the ratio of the minor axis to the major axis (r2 / r1) is in the range of 0.5 to 1.0. The ratio (r3 / r2) to the minor axis is in the range of 0.7 to 1.0, and the relationship of major axis r1 ≧ minor axis r2 ≧ thickness r3 is satisfied. The image forming apparatus according to claim 1.

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