JP2008020810A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of smoothly coating the surface of a toner carrier with a lubricant in a state where the surface of the toner carrier is cleaned. <P>SOLUTION: The image forming apparatus comprises: a lubricant coating means 62 for coating the surface of a toner carrier 35 with a lubricant; a cleaning means 66 for cleaning the surface of the toner carrier 35 provided on the upstream side in the rotational direction of the toner carrier 35 than the lubricant coating means 62; and a lubricant smoothing means 67 for smoothing the lubricant coated on the surface of the toner carrier 35. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  As an image forming apparatus, a plurality of toner images sequentially formed on an image carrier such as a photosensitive member or an intermediate transfer belt are sequentially superimposed and primarily transferred onto an endless moving intermediate transfer member. 2. Description of the Related Art An intermediate transfer type image forming apparatus that performs secondary transfer of a primary transfer image (toner image) collectively onto a transfer material is known. Image forming apparatuses using this intermediate transfer method are particularly advantageous in that they can be downsized in recent years and that there are few restrictions on the type of transfer material onto which a visible image is finally transferred. It is used as a device.

  The intermediate transfer type image forming apparatus is liable to cause a transfer failure at each stage of primary transfer and secondary transfer of each color toner image. For this reason, there is a method of reducing the adhesion force with the toner by applying a lubricant to the surface of the image carrier. There is a method in which an application brush is rotated while being in contact with a solid lubricant (solid lubricant), and the lubricant is transferred onto the application brush and applied to the surface of an application member such as an image carrier. As a result, the static friction coefficient μs with respect to the toner on the surface of the member to be coated is lowered so that the toner image can be satisfactorily transferred to the transfer material side.

  However, even if the lubricant is applied as described above, the transfer of the toner image is not performed well, so that the image portion called “worm biting” is deflated, or the image portion called “image blur” is attached to the toner. Various abnormal images such as shortage or a so-called “buzzy” blurred image are generated.

  Since the toner remains on the surface of the coated member even after the toner image is transferred, it is necessary to clean the residual toner. The following two patterns can be considered for the two steps of applying the lubricant and cleaning the residual toner after the transfer. That is, there are two patterns: a relationship of post-application cleaning in which the lubricant is applied first and cleaning is later, and a relationship of post-cleaning application in which the cleaning is first and lubricant is applied later. Since each pattern has a different mechanism for generating an abnormal image, description will be given separately for each pattern.

  FIG. 1 is a partially enlarged view of the vicinity of a lubricant application portion having a configuration of post-application cleaning.

  Referring to FIG. 1, the belt 11 to be applied moves in the direction of the arrow in the drawing in the order of the support roller 15, the facing member 16, and the bending roller 17. An application brush 12 as an application member is in contact with the surface of the application belt 11 that is an image carrier, and a cleaning blade 13 is in contact with the surface of the application belt 11 on the downstream side of the surface movement direction. Thus, the lubricant 14 is applied to the surface of the belt 11 to be applied by the application brush 12, and then the surface is cleaned by the cleaning blade 13. In such post-application cleaning, the lubricant 14 is applied to the surface of the belt 11 to be applied in a state where the toner remains without being removed. Here, the portion corresponding to the character portion of the image originally carried on the surface of the coated belt 11 has a lot of residual toner on the surface of the coated belt 11 even after transfer to the transfer material, and the portion other than the character portion is Virtually no residual toner is present. Since a large amount of lubricant 14 is scraped off together with the toner by the application brush 12 and the cleaning blade 13 at the cleaning position, the surface of the belt 11 to be applied after passing through the cleaning position. In this case, the amount of the lubricant 14 applied becomes uneven. In particular, when the same image is output continuously, the portion with a large amount of residual toner on the surface of the belt 11 to be coated is always the same, and such a bias becomes significant. Further, since residual toner adheres to the application member such as the application brush 12, the application brush becomes dirty, and it becomes difficult to continue to apply the lubricant 14 uniformly over a long period of time. If the uniform lubricant 14 layer cannot be formed on the surface of the belt 11 to be coated, unevenness of the static friction coefficient μs of the surface is generated, or the transfer unevenness occurs because the surface does not have a sufficiently low value for transferring the toner. , Bug eaters, image blurring, blurry images, etc.

  FIG. 2 is a partially enlarged view of the vicinity of a lubricant application portion having a configuration of application after cleaning.

  Referring to FIG. 2, the belt 11 to be coated moves in the direction of the arrow in the drawing in the order of the support roller 15, the facing member 16, and the bending roller 17. An application brush 12 as an application member is in contact with the surface of the application belt 11 that is an image carrier, and a cleaning blade 13 is in contact with the surface of the application belt 11 on the upstream side in the movement direction. As a result, the surface of the belt 11 to be coated is cleaned by the cleaning blade 13 and then the lubricant 14 is applied by the coating brush 12. If such post-cleaning application is performed, the lubricant 14 after application is not scraped off by the cleaning blade 13, so that the above-described problems in the post-application cleaning configuration can be prevented. However, when the surface of the belt 11 to which the lubricant 14 is applied enters the transfer position as it is and transfer is performed, the occurrence of an abnormal image is recognized even though the static friction coefficient μs of the surface is within the appropriate range. It was. This is because the particles of the lubricant 14 are not fine enough to form a uniform layer just by being applied, and therefore the layer thickness is uneven on the surface of the belt 11 to be applied, and this clearly affects the transferability of the toner. became. If a uniform lubricant 14 layer cannot be formed on the surface of the member 11 to be coated, the surface static friction coefficient μs does not become uniform, or does not become a sufficiently low value for transferring toner, resulting in transfer unevenness. Abnormal images such as bug eaters, image blurs, and blurs.

  For this reason, there has been proposed a method that enables uniform application of the lubricant to the image carrier by increasing the density of the hair of the application brush for applying the lubricant (see, for example, Patent Document 1).

In addition, a method has been proposed that enables uniform application of the lubricant by uniformizing the amount of lubricant carried on the lubricant carrying member on the lubricant carrying member and then applying it to the carried member. (For example, refer to Patent Document 2).
Japanese Patent Laid-Open No. 10-260614 JP 7-295451 A

  However, in the image forming apparatus disclosed in Patent Document 1, since the surface of the supported member is cleaned after the lubricant is applied, it is possible to completely prevent the residual toner from adhering to the application brush. Can not.

  Further, in the image forming apparatus disclosed in Patent Document 2, the lubricant is uniformly applied for the purpose of improving the cleaning performance of the supported member to which the lubricant is applied. However, it is not described that the above-mentioned problem can be prevented as an effect.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an image forming apparatus capable of smoothly applying a lubricant to the surface of the toner carrier while the surface of the toner carrier is cleaned. And

  In order to achieve the above object, the present invention is characterized by the following measures.

  An image forming apparatus according to the present invention includes a toner carrier that carries toner, and in the image forming apparatus that forms an image using the toner, a lubricant application unit that applies a lubricant to the surface of the toner carrier; A cleaning unit for cleaning the surface of the toner carrier provided on the upstream side in the rotation direction of the toner carrier from the lubricant application unit, and a downstream side in the rotation direction of the toner carrier from the lubricant application unit. And a lubricant smoothing means for smoothing the lubricant applied to the surface of the toner carrier.

  In the image forming apparatus of the present invention, the lubricant smoothing means includes a blade.

  In the image forming apparatus of the present invention, the blade is an elastic body.

  An image forming apparatus according to the present invention includes a toner carrier that carries toner, and in the image forming apparatus that forms an image using the toner, a lubricant application unit that applies a lubricant to the surface of the toner carrier; A first cleaning means for cleaning the surface of the toner carrier provided upstream of the lubricant application means in the rotation direction of the toner carrier; and a rotation direction of the toner carrier relative to the lubricant application means And a second cleaning means for cleaning the surface of the toner carrier provided on the downstream side.

  In the image forming apparatus of the present invention, the first cleaning unit includes a first blade, and the second cleaning unit includes a second blade.

  In the image forming apparatus of the present invention, the first and second blades are elastic bodies.

  In the image forming apparatus of the present invention, the linear pressure on the toner carrier per unit length of the first blade is equal to or higher than the linear pressure on the toner carrier per unit length of the second blade. is there.

  In the image forming apparatus of the present invention, the second cleaning means is means for smoothing the lubricant applied to the surface of the toner carrier and cleaning the surface of the toner carrier.

  In the image forming apparatus of the present invention, the volume average particle diameter of the toner is 3 μm or more and 8 μm or less, and the ratio of the volume average particle diameter of the toner to the number average particle diameter of the toner is 1.00 or more and 1. 40 or less.

  In the image forming apparatus of the present invention, the shape factor SF-1 of the toner is 100 or more and 180 or less, and the shape factor SF-2 of the toner is 100 or more and 180 or less.

  The image forming apparatus according to the present invention is manufactured by crosslinking and / or extending a toner composition in which the toner includes a polyester prepolymer containing at least an isocyanate group, a polyester, a colorant, and a release agent in an aqueous medium. Is done.

  In the image forming apparatus of the present invention, the toner is the longest first axis among the toner axes, the longest second axis perpendicular to the first axis, and the first and first axes. A third axis perpendicular to the second axis, the ratio of the length of the second axis to the length of the first axis being between 0.5 and 1.0, and The ratio of the length of the third shaft to the length of the second shaft is 0.7 or more and 1.0 or less.

  As described above, according to the present invention, there is provided an image forming apparatus capable of providing an image forming apparatus that can smoothly apply a lubricant to the surface of the toner carrying member while the surface of the toner carrying member is cleaned. It becomes possible.

  Next, the best mode for carrying out the present invention will be described as an embodiment with reference to the drawings.

  FIG. 3 is a schematic configuration diagram of the image forming apparatus according to the embodiment of the present invention.

  Referring to FIG. 3, the image forming apparatus 30 generally includes an apparatus main body 31, a paper feed table 32, a scanner 33, and an automatic document feeder 34.

  The apparatus main body 31 is provided with a belt apparatus including an intermediate transfer belt 35 formed of an endless belt. The intermediate transfer belt 35 as a toner carrier is stretched around a drive roller 36, a support roller 37, a support roller 38, and a curved roller 39, and is driven to rotate clockwise in the drawing. A belt cleaning device 40 for removing toner remaining on the intermediate transfer belt 35 (hereinafter referred to as residual toner) after the secondary transfer is provided. In the apparatus main body 31, four image forming units 41 that form toner images of black, yellow, magenta, and cyan are arranged side by side along the belt outer peripheral surface of the intermediate transfer belt 35. On each of these image forming units 41, an exposure device 42 is provided. A fixing device 43 is disposed below the belt device. Further, below the fixing device 43, a sheet reversing device 45 that reverses the transfer paper 44 to record images on both sides of the transfer paper 44 is provided.

  In order to form an image using the image forming apparatus 30, a document is set on the document table of the automatic document feeder 34. Alternatively, the automatic document feeder 34 is opened, a document is set on the contact glass of the scanner 33, the automatic document feeder 34 is closed, and the document is pressed by the automatic document feeder 34. Next, a start switch (not shown) is pressed. As a result, when a document is set on the automatic document feeder 34, the document is conveyed onto the contact glass. When a document is set on the contact glass, the scanner 33 is immediately driven to read the document image.

  On the other hand, when the start switch is pressed, the drive roller 36 is rotated by a drive motor (not shown). As a result, the intermediate transfer belt 35 is driven and rotated in a predetermined direction. At the same time, black, yellow, magenta, and cyan single color toner images are formed on the respective photoreceptors of the individual image forming units 41. Then, with the rotation of the intermediate transfer belt 35, these single color toner images are sequentially primary transferred onto the intermediate transfer belt 35. As a result, a full-color composite toner image is formed on the intermediate transfer belt 35.

  Further, when the start switch described above is pressed, one of the paper feed rollers 46 of the paper feed table 32 is selected and rotated. As a result, the transfer paper 44 is fed out from the corresponding one paper feed cassette 47. The transfer paper 44 is separated and conveyed one by one, and waits in a state of being abutted against the registration roller 48. The transfer sheet 44 is fed between the intermediate transfer belt 35 and the secondary transfer roller 49 by rotating the registration roller 48 in synchronization with the composite color image on the intermediate transfer belt 35. As a result, a color image is recorded on the transfer paper 44.

  The transfer paper 44 after the secondary transfer is sent to the fixing device 43. Then, the secondary transfer toner image is fixed on the transfer paper 44 by being heated and pressurized by the fixing device 43. The transfer paper 44 on which the secondary transfer toner image is fixed is discharged out of the apparatus main body 31 and stacked on the paper discharge tray 50. When images are formed on both surfaces of the transfer paper 44, after the images are formed on the surface as described above, the switching claw 51 is switched and the transfer paper 44 is guided to the sheet reversing device 45. The sheet reversing device 45 reverses the image forming surface of the transfer paper 44, and the transfer paper 44 is guided to the secondary transfer portion again. After the image is recorded and fixed on the back surface of the transfer paper 44, the transfer paper 44 is discharged out of the apparatus main body 31 and stacked on the paper discharge tray 50. On the other hand, the residual toner remaining on the outer peripheral surface of the intermediate transfer belt 35 after the secondary transfer is removed by the belt cleaning device 40.

  FIG. 4 is a schematic diagram for explaining the shape factor SF-1 and the shape factor SF-2 that are coefficients indicating the toner shape used in the image forming apparatus of the present embodiment.

  In order to cope with recent rapid colorization and high image quality associated therewith, small diameter, narrow particle size distribution, and spheroidization (true sphere) using polymerized toner are becoming mainstream. The distribution of toner with a small diameter and a narrow particle diameter is advantageous for high-resolution development, and the spherical shape is advantageous for transfer efficiency, and the image quality such as the sharpness of the toner image is remarkably improved.

  However, when the particle size of the toner is reduced, the specific surface area of the toner adhering to the surface of the image carrier such as the photosensitive member or the intermediate transfer belt increases. As a result, the adhesion force of the toner per unit weight to the surface of the image carrier increases, and it becomes difficult to clean the surface of the image carrier. Further, the reduction in the toner particle diameter causes deterioration of the fluidity of the toner, and a large amount of additive is required to maintain proper fluidity. However, this additive is known to cause the chipping or abrasion of the cleaning blade, local streak scratches on the surface of the image carrier, and the like.

  Further, when the sphericity of the toner is increased, the above-described blade counter contact method generally used in the related art increases the amount of toner passing through the blade, so that it is necessary to increase the contact pressure more than before. Become. However, raising the contact pressure causes a problem that edge chipping occurs due to local shearing force of the blade.

  The toner used in the image forming apparatus of this embodiment will be described.

  In order to reproduce fine dots of 600 dpi or more, the toner preferably has a volume average particle diameter of 3 μm or more and 8 μm or less. The ratio (Dv / Dn) of the volume average particle diameter (Dv) of the toner to the number average particle diameter (Dn) of the toner is preferably 1.00 or more and 1.40 or less. The closer (Dv / Dn) 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 has a high transfer rate. can do.

  Dv and Dn are measured using a precision particle size distribution measuring device (multisizer).

  Further, the shape factor SF-1 of the toner is preferably 100 or more and 180 or less, and the shape factor SF-2 is preferably 100 or more and 180 or less.

  Referring to FIG. 4A, the shape factor SF-1 indicates the ratio of the roundness of the toner shape, and SF-1 represented by the following formula (1) indicates that the toner is in a two-dimensional plane. This is a value obtained by dividing the square of the absolute maximum length MXLNG of the toner particles formed by projection by the projected area AREA of the toner particles and multiplying by 100π / 4.

SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
The value of SF-1 indicates the degree of roundness of the toner particles. When the value of SF-1 is 100, the shape of the toner is a true sphere, and becomes irregular as the value of SF-1 increases.

  Referring to FIG. 4B, the shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and SF-2 represented by the following formula (2) indicates that the toner is in a two-dimensional plane. This is a value obtained by dividing the square of the peripheral length PERI of the projected toner particles by the projected area AREA of the toner particles and multiplying by 100π / 4.

SF-2 = {(PERI) ² / AREA} × (100π / 4) Expression (2)
The value of SF-2 indicates the degree of unevenness on the toner particle surface. When the value of SF-2 is 100, there is no unevenness on the toner surface, and the unevenness of the toner surface becomes more prominent as the value of SF-2 increases.

  Specifically, the shape factor is measured by taking a photograph of the toner at a magnification of 500 to 5000 times with an optical microscope or a scanning electron microscope (Hitachi 2700, manufactured by Hitachi, Ltd.), and using the photograph as an automatic image analysis processing device. (LUZEX AP: manufactured by Nireco), and the shape factor was calculated.

  When the shape of the toner is close to a sphere, the contact state between the toner and the toner or between the toner and the image carrier becomes point contact. For this reason, the attractive force between the toners becomes weak and accordingly the fluidity becomes high, and the attractive force between the toner and the image carrier becomes weak and the transfer efficiency becomes high. Therefore, toner having one of the shape factors SF-1 and SF-2 exceeding 180 is not suitable for use as the toner of the image forming apparatus of this embodiment because the transfer efficiency is lowered.

  A toner suitably used in the image forming apparatus of the present embodiment includes at least a polyester prepolymer having a functional group containing a nitrogen atom such as an isocyanate group, a polyester, a colorant, and a release agent in an organic solvent. The toner composition is obtained by subjecting the toner composition dispersed in the toner composition to at least one of a crosslinking reaction or an elongation reaction in an aqueous solvent. Hereinafter, the constituent material and the manufacturing method of the toner will be described.

(polyester)
The polyester is obtained by a polycondensation reaction between a polyhydric alcohol and a polyvalent carboxylic acid.

  Examples of the polyhydric alcohol include dihydric alcohols and trihydric or higher polyhydric alcohols. In particular, a dihydric alcohol alone or a mixture of a dihydric alcohol and a small amount of a trihydric or higher polyhydric alcohol is preferable.

  Examples of the dihydric alcohol include alkylene glycol (such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, and 1,6-hexanediol), alkylene ether glycol (diethylene glycol, triethylene glycol, Ethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol), alicyclic diols (such as 1,4-cyclohexanedimethanol and hydrogenated bisphenol A), bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.), alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts of the above alicyclic diols, Fine above bisphenols alkylene oxides (ethylene oxide, propylene oxide, and butylene oxide) such adducts. Of these, preferred are alkylene glycol adducts of alkylene glycols and bisphenols having 2 to 12 carbon atoms, and particularly preferred are alkylene oxide adducts of bisphenols, alkylene oxide adducts and alkylene oxide adducts of 2 to 12 carbon atoms. The following alkylene glycol is used in combination.

  Examples of the trihydric or higher polyhydric alcohol include trihydric or higher polyhydric aliphatic alcohols (such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and sorbitol), and trihydric or higher phenols (trisphenol PA, phenol). Novolak and cresol novolak), and alkylene oxide adducts of the above trivalent or higher phenols.

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

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

  A polycondensation reaction between a polyhydric alcohol and a polycarboxylic acid is generated in the presence of a known esterification catalyst such as tetrabutoxy titanate or dibutyltin oxide, and heated to 150 ° C. or higher and 280 ° C. or lower and reduced pressure as necessary. 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 or more and 30 or less, preferably 5 or more and 20 or less. By giving an acid value, it tends to be negatively charged, and when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixability of the toner is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate due to the stability of charging, particularly environmental fluctuation.

  The polyester has a weight average molecular weight of 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 of the toner is deteriorated. Further, if the weight average molecular weight exceeds 400,000, the low-temperature fixability of the toner is deteriorated, which is not preferable.

  The polyester preferably contains a urea-modified polyester in addition to the unmodified polyester obtained by the above polycondensation reaction. The urea-modified polyester is obtained by reacting a terminal carboxyl group or hydroxyl group of the polyester obtained by the polycondensation reaction with a polyvalent isocyanate compound to obtain a polyester prepolymer (A) having an isocyanate group. The molecular chain is obtained by at least one of crosslinking and extension by the reaction of A) with amines.

  Examples of polyisocyanate compounds include aliphatic polyisocyanates (such as tetramethylene diisocyanate, hexamethylene diisocyanate, and 2,6-diisocyanatomethylcaproate), and alicyclic polyisocyanates (such as isophorone diisocyanate and cyclohexylmethane diisocyanate). , Aromatic diisocyanates (such as tolylene diisocyanate and diphenylmethane diisocyanate), araliphatic diisocyanates (such as α, α, α ′, α′-tetramethylxylylene diisocyanate), and polyisocyanates such as phenol derivatives, oximes, caprolactam What was blocked, and these 2 or more types combined use are mentioned.

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

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

  The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 in average, more preferably 1.8 in average. The number is 2.5 or more. When the number is less than 1 per molecule, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance of the toner is deteriorated.

  Next, as the amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine (B2), an amino alcohol (B3), and an amino mercaptan (B4). , Amino acid (B5), and compound (B6) in which the amino group of B1 to B5 is blocked.

  Examples of the divalent amine (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.) and 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 (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 compound (B6) in which the amino group of B1 to B5 is blocked include ketimine compounds obtained from the amines of B1 to B5 and ketones (such as acetone, methyl ethyl ketone, and methyl isobutyl ketone), and oxazolidine compounds. It is done. Among these amines (B), B1 and a mixture of B1 and a small amount of B2 are preferable.

The ratio of amines (B) to urea-modified polyester is the equivalent ratio of isocyanate groups (NCO) in the polyester prepolymer (A) having isocyanate groups and amino groups (NH _x ) in the amines (B) [ NCO] / [NH _x ] is usually from 1/2 to 2/1, preferably from 1.5 / 1 to 1 / 1.5, more preferably from 1.2 / 1 to 1 / 1.2. is there. When [NCO] / [NH _x ] is 2 or more or 1/2 or less, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance of the toner is deteriorated.

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

  When reacting the polyvalent isocyanate and reacting the polyester prepolymer (A) and the amines (B), a solvent may be used as necessary. Solvents that can be used include aromatic solvents (such as toluene and xylene), ketones (such as acetone, methyl ethyl ketone, and methyl isobutyl ketone), esters (such as ethyl acetate), and amides (such as dimethylformamide and dimethylacetamide). ) And ethers (such as tetrahydrofuran) and the like which are inert to isocyanates.

  Moreover, the molecular weight of the urea modified polyester obtained can be adjusted by using a reaction terminator for the crosslinking reaction or elongation reaction of the polyester prepolymer (A) and the amines (B), if necessary. Examples of the reaction terminator include monoamines (such as diethylamine, dibutylamine, butylamine, and laurylamine), and those obtained by blocking them (ketimine compounds).

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

  By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability of the toner and the gloss of the toner when used in the full-color image forming apparatus 100 are improved. Therefore, it is preferable to use the urea-modified polyester alone. A modified polyester modified with a chemical bond other than a urea bond may be used.

  It is preferable that at least a part of the unmodified polyester and the urea-modified polyester are compatible from the viewpoint of low-temperature fixability and hot offset resistance of the toner. 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 or more and 95/5 or less, preferably 70/30 or more and 95/5 or less, more preferably 75/25 or more and 95/5 or less, particularly preferably. Is 80/20 or more and 93/7 or less. If the weight ratio of the urea-modified polyester is less than 5%, the hot offset resistance of the toner is deteriorated, and it is disadvantageous in terms of both the heat-resistant storage stability and the low-temperature fixability of the toner.

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

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

(Coloring agent)
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, and G), cadmium yellow, yellow iron oxide, ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa Yellow (GR, A, RN, and R), Pigment Yellow L, Benzidine Yellow (G and GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G and R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, isoindolinone yellow, bengara, red lead, red lead, cadmium red, cadmium mercurial red, antimony red, permanent red 4R, para red, phissa red, parachloro ortho nitroaniline red, risor fast scar G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, and F4RH), Fast Scarlet VD, Velcan 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, Thioindigo Red B , Thioindigo maroon, oil red, quinacridone red, pyrazolone red, polyazo 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 and 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, Phthalocyanine Green, Anthraquinone Green , Titanium oxide, zinc white, litbon, and mixtures thereof can be used. The content of the colorant is usually from 1% to 15% by weight, preferably from 3% to 10% by weight, based on the toner.

  The colorant can also be used as a master batch combined with a resin. As a binder resin to be kneaded together with the production of a masterbatch or a masterbatch, styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene and the like, a polymer of its substitution product, and a copolymer of the polymer and a vinyl compound , 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 paraffins, paraffin waxes 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. For example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus Simple substance or compound, tungsten simple substance or compound, fluorine-based activator, salicylic acid metal salt, metal salt of salicylic acid derivative, and the like. Specifically, Bontron 03 of nigrosine dye, Bontron P-51 of quaternary ammonium salt, Bontron S-34 of metal-containing azo dye, E-82 of oxynaphthoic acid metal complex, E- of salicylic acid metal complex 84, E-89 of phenol-based condensate (above, manufactured by Orient Chemical Co., Ltd.), TP-302, TP-415 of quaternary ammonium salt molybdenum complex (made of Hodogaya Chemical Co., Ltd.), quaternary ammonium salt Copy charge PSYVP 2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo series Examples thereof include pigments and other polymer compounds having functional groups such as sulfonic acid groups, carboxyl groups, and 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 parts by weight or more and 5 parts by weight or less 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 attractive force between the developing roller and the toner is increased, the toner fluidity is reduced, and the toner image density is increased. Cause a decline.

(Release agent)
As the release agent, a low melting point wax having a melting point of 50 ° C. or more and 120 ° C. or less effectively works as a release agent between the fixing roller and the toner interface in the dispersion with the binder resin. Accordingly, it is possible to exhibit a release effect against high temperature offset without applying an oil-like release agent to the fixing roller.

  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, and rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline, And petroleum waxes such as petrolatum. 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. Furthermore, fatty acid amides such as 12-hydroxystearic amide, stearic amide, phthalic anhydride, chlorinated hydrocarbons, and poly-n-stearyl methacrylate and poly-n-lauryl which are low molecular weight crystalline polymer resins A crystalline polymer having a long alkyl group in the side chain, such as a homopolymer or copolymer of a polyacrylate such as methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate) or the like can also be used.

  The charge control agent and the release agent may be melt-kneaded together with the master batch and the binder resin, or may be added when dissolved or dispersed in an organic solvent.

(External additive)
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 μm or more and 2 μm or less, and particularly preferably 5 × 10 ⁻³ μm or more and 0.5 μm or less. The specific surface area by the BET method is preferably ^{20 m} 2 / g or more 500m ² / g or less. The use ratio of the inorganic fine particles is preferably 0.01% by weight or more and 5% by weight or less of the toner, and particularly preferably 0.01% by weight or more and 2.0% by weight or less.

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, silica sand, clay, mica, wollastonite, Examples thereof include diatomaceous earth, 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, the electrostatic force (Van der Waals force) between the toners is remarkably high when the agitation and mixing are performed using fine particles having an average particle size of 5 × 10 ⁻² μm or less of the hydrophobic silica fine particles and the hydrophobic titanium oxide fine particles. To improve. Therefore, even when a desired charge level is obtained by stirring and mixing inside the developing device, the fluidity-imparting agent is not detached from the toner, and good image quality that does not cause a spot that oozes out in a firefly shape can be obtained. Further, it is possible to reduce toner remaining on the surface of the carrying member without being transferred to the carried member.

  Titanium oxide fine particles are excellent in environmental stability and image density stability, but on the other hand, they show a tendency to deteriorate the charge rising characteristics. If the amount of titanium oxide fine particles added is larger than the amount of silica fine particles added, it is considered that the influence of deterioration of the charge rising characteristics becomes 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 wt% or more and 1.5 wt% or less, the charge rising characteristics are not greatly impaired, and the desired charge rising characteristics can be obtained. Therefore, stable image quality can be obtained even when copying is repeated.

(Toner production method)
A method for producing toner will be described. Here, although a preferable manufacturing method is shown, it is not limited to this.

  (1) A toner composition liquid 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, And methyl isobutyl ketone 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 amount of the organic solvent used is usually 0 to 300 parts by weight, preferably 0 to 100 parts by weight, more preferably 25 to 70 parts by weight, based on 100 parts by weight of the polyester prepolymer. .

  (2) The toner composition liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles. The aqueous medium may be water alone, such as alcohol (methanol, isopropyl alcohol, and ethylene glycol), dimethylformamide, tetrahydrofuran, cellosolves (such as methylcellosolve), and lower ketones (such as acetone and methylethylketone). An organic solvent may be included.

  The amount of the aqueous medium used is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight, based on 100 parts by weight of the toner composition liquid. In addition, the aqueous medium used here assumes that the main component is not an organic compound but water. If the amount is less than 50 parts by weight, the dispersion state of the toner composition 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 of the toner composition liquid in the aqueous medium, a surfactant and a dispersant such as resin fine particles are appropriately added.

  Surfactants include anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, and phosphate esters, alkylamine salts, amino alcohol derivatives, polyamine derivatives, and amine salt types such as imidazoline, alkyls. Quaternary ammonium salt type cationic surfactants such as trimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, and benzethonium chloride, fatty acid amide derivatives, and polyvalent Nonionic surfactants such as alcohol derivatives and amphoteric boundaries such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine, and N-alkyl-N, N-dimethylammonium betaine Active agents.

Further, by using a surfactant having a fluoroalkyl group, the surface active effect can be increased 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 (C ₆ -C ₁₁₎ oxy] -1-alkyl _(C 3 ~C ₄₎ sodium sulfonate, 3- [.omega.-fluoroalkanoyl _{(C 6} ~C 8) -N- ethylamino] -1-sodium sulfonic acid, fluoro alkyl _(C 11 _{~C 20)} carboxylic acids and metal salts thereof, perfluoroalkyl carboxylic acids _(C 7 _{~C 13)} and metal salts thereof, perfluoroalkyl _(C 4 _{~C 12)} sulfonic acids and metal salts thereof, perfluoroalkyl Fluorooctanesulfonic acid diethanolamide, N-propyl-N- (2- Hydroxyethyl) perfluorooctane sulfonamide, perfluoroalkyl _(C 6 _{-C 10)} sulfonamide propyl trimethyl ammonium salts, perfluoroalkyl _{(C 6} -C 10)-N-ethylsulfonyl glycine salts, and monoperfluoroalkyl ( C ₆ -C ₁₆ ) ethyl phosphate and the like.

  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 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), Fantent F-100, and F150 (manufactured by Neos).

Examples of the cationic surfactant include aliphatic primary or secondary amino acids having a fluoroalkyl group, aliphatic quaternary ammonium salts such as perfluoroalkyl (C ₆ -C ₁₀ ) sulfonamidopropyltrimethylammonium salt, Benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (Asahi Glass), Florard FC-135 (Sumitomo 3M), Unidyne DS-202 (Daikin Industries) ), Megafuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products Co., Ltd.), and Footgent F-300 (Neos Co., Ltd.).

  The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. Therefore, the resin fine particles are preferably added so that the coverage on the surface of the toner base particles is in the range of 10% to 90%. For example, there are polymethyl methacrylate fine particles having a diameter of 1 μm and 3 μm, polystyrene fine particles having a diameter of 0.5 μm and 2 μm, and poly (styrene-acrylonitrile) fine particles having a diameter of 1 μm. In terms of product names, PB-200H (manufactured by Kao Corporation), SGP (manufactured by Sokensha), technopolymer SB (manufactured by Sekisui Plastics Co., Ltd.), SGP-3G (manufactured by Sokensha), and Micropearl (manufactured by Sekisui Fine Chemical) Etc.

  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 an inorganic compound dispersant, the dispersed droplets may be stabilized by a polymeric protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride and other acids or hydroxyl groups containing (meth) acrylic Monomers 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 -Hydroxypropyl, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monometa The Rylic acid ester, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers such as vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc., or a compound containing vinyl alcohol and a carboxyl group Esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acrylates, methacrylates and other acid salts, vinyl pyridine, vinyl pyrrolidone, vinyl imidazole , Nitrogen-containing compounds such as ethyleneimine, or homopolymers and copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, polyoxypropylene, polyoxy Ethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonyl phenyl ester, etc. Celluloses such as polyoxyethylene, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose and the like can be used.

  The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, 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 μm or more and 20 μm or less. When a high-speed shearing disperser is used, the number of rotations is not particularly limited, but is usually from 1000 to 30000 rotations / second, preferably from 5000 to 20000 rotations / second. The dispersion time is not particularly limited, but in the case of a batch method, it is usually from 0.1 minutes to 5 minutes. The temperature during dispersion is usually from 0 ° C. to 150 ° C. (under pressure), preferably from 40 ° C. to 98 ° C.

  (3) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group.

  This reaction involves at least one of molecular chain crosslinking and elongation. The reaction time is selected depending on the reactivity between the isocyanate group of the polyester prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 hours to 24 hours. The reaction temperature is usually 0 ° C. or higher and 150 ° C. or lower, preferably 40 ° C. or higher and 98 ° C. or lower. 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 dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. Remove. It can also be removed by an operation such as enzymatic degradation.

  (5) A charge control agent is added to the toner base particles obtained above, and inorganic fine particles such as silica fine particles and titanium oxide fine particles are externally added to obtain a toner.

  The addition of the charge control agent and the inorganic fine particles is 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 giving strong agitation in the process of removing the organic solvent, the shape between the true spherical shape and the rugby ball shape can be controlled, and the toner surface shape is also controlled between the smooth one and the umeboshi shape. can do.

  FIG. 5 is a schematic diagram of a toner shape used in the image forming apparatus of this embodiment. The shape of the toner according to the present embodiment is a substantially spherical shape, and can be expressed by the following shape rule.

  Referring to FIG. 5, the longest axis among the axes of the substantially spherical toner 100 is the long axis r1, the longest axis perpendicular to the long axis is the short axis r2, and the long and short axes. The axis that is perpendicular to is defined as the thickness r3. At that time, in the toner 100 of this embodiment, the ratio of the major axis to the minor axis (r2 / r1) (shown in FIG. 5B) is 0.5 to 1.0, and the thickness and minor axis are The ratio (r3 / r2) (shown in FIG. 5C) is preferably in the range of 0.7 to 1.0. 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 short axis (r3 / r2) is 1.0, the rotating body has the long axis as the rotation axis, and the fluidity of the toner 100 can be improved.

  The method for measuring r1, r2, and r3 of the toner 100 is as follows. After placing the sample on a conductive tape and performing Pt-Pd vapor deposition, it was observed with a scanning electron microscope (FE-SEM S-4200: manufactured by Hitachi) at a magnification of about 1000 to 10,000 times under a measurement condition of an acceleration voltage of 8 KV. Measurements were made.

  FIG. 6 is a partially enlarged view showing the lubricant application portion of the image forming apparatus of this embodiment.

  In this embodiment, a lubricant is applied to the surface of the photoreceptor and the intermediate transfer belt so that the static friction coefficient μs of both can be maintained at an appropriate value. Here, since the lubricant applying unit to the photosensitive member and the lubricant applying unit to the intermediate transfer belt have the same configuration, the lubricant applying unit to the intermediate transfer belt will be described below as an example. Although the belt shape will be described as an example, the photosensitive member and the intermediate transfer member may be any of a belt shape, a drum shape, and a roller shape.

  Referring to FIG. 6, the lubricant application portion that applies the lubricant to the intermediate transfer belt 35 in the image forming apparatus 30 is partially enlarged. The lubricant application unit 60 is provided in the belt cleaning device 40 shown in FIG. 3. In brief, the intermediate transfer belt 35 as a toner carrier, a support roller 71, a first facing member 72, and a second counter member are provided. The counter member 73 includes a curved roller 74, a solid lubricant 61, a brush roller 62, a lubricant holding member 63, a pressure spring 64, a cleaning blade 66, and a lubricant uniformizing blade 67.

  The intermediate transfer belt 35 moves in the direction of the arrow in the drawing in the order of the support roller 71, the first opposing member 72, the second opposing member 73, and the bending roller 74.

  The solid lubricant 61 was formed into a bar shape by cooling and solidifying a lubricant additive mainly composed of zinc stearate by heating. The solid lubricant 61 is held by a lubricant holding member 63, and the solid lubricant 61 is pressed against the brush roller 62 via the lubricant holding member 63 by a pressure spring 64 attached to the apparatus housing 65.

  As the solid lubricant 61, a dry solid hydrophobic lubricant can be used. Besides zinc stearate, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, Those having a stearic acid group such as copper stearate, strontium stearate, calcium stearate, cadmium stearate, and magnesium stearate can be used. In addition, the same fatty acid groups zinc oleate, manganese oleate, iron oleate, cobalt oleate, lead oleate, magnesium oleate, copper oleate, palmitic acid, cobalt zinc palmitate, copper palmitate, magnesium palmitate Aluminum palmitate and calcium palmitate may also be used. In addition, metal salts of fatty acids such as lead caprylate, lead caproate, zinc linolenate, cobalt linolenate, calcium linolenate, and cadmium ricolinolenate can also be used. In addition, waxes such as candelilla wax, carnauba wax, rice wax, wax, ooba oil, beeswax and lanolin can be used.

  The brush roller 62 is in the vicinity of the second facing member 73 and is provided in contact with the intermediate transfer belt 35 as a lubricant application unit. As the brush roller 62 rotates, the solid lubricant 61 is scraped to the brush roller 62 side, and the solid lubricant 61 adhering to the brush roller 62 adheres to the surface of the intermediate transfer belt 35 from the contact portion with the intermediate transfer belt 35.

  The cleaning blade 66 is provided in the vicinity of the first opposing member 72 upstream of the movement direction of the intermediate transfer belt 35 with respect to the lubricant application position by the brush roller 62. The cleaning blade 66 is in contact with the surface of the intermediate transfer belt 35 as a cleaning unit. The cleaning blade 66 is made of rubber which is an elastic body.

  The lubricant uniformizing blade 67 is provided downstream of the lubricant application position by the brush roller 62 in the moving direction of the intermediate transfer belt 35. The lubricant uniformizing blade 67 is in contact with the surface of the intermediate transfer belt 35 as a lubricant uniformizing means. The lubricant uniformizing blade 67 is made of rubber which is an elastic body.

  In this embodiment, the cleaning blade 66 is brought into contact with the surface of the intermediate transfer belt 35 from the counter direction, and the lubricant uniformizing blade 67 is brought into contact with the surface of the photosensitive member from the trailing direction. The combination of the trailing directions is not limited to this.

  Next, characteristics of the lubricant application unit 60 in the image forming apparatus 30 of this embodiment will be described. In the above configuration, the residual toner remaining on the surface of the intermediate transfer belt 35 after the toner image carried on the surface is secondarily transferred to the transfer paper is first removed by the cleaning blade 66. As a result, the brush roller 62 comes into contact with the surface of the intermediate transfer belt 35 in a clean state, and the lubricant derived from the solid lubricant 61 is applied. When the applied lubricant passes the contact position of the lubricant uniformizing blade 67 on the downstream side in the moving direction of the surface of the intermediate transfer belt 35, the surface is smoothed and uniformly spread, and the lubricant having a uniform thickness is provided. It becomes a layer of agent.

  After cleaning the residual toner, a method of cleaning after application (see FIG. 1), in which the intermediate transfer belt is cleaned only after the lubricant is applied, by applying a lubricant and further forming a uniform layer of lubricant. Both of the above-mentioned problems caused by the post-cleaning application method (see FIG. 2) in which the lubricant is applied after cleaning can be prevented. In other words, the application amount of the lubricant is uneven due to the cleaning after the application, and the surface static friction coefficient is uneven, or the uniform lubricant layer cannot be formed on the surface of the intermediate transfer belt 35 by the application after the cleaning. It is possible to prevent the occurrence of abnormal images such as bug eaters, image blurs, and blurs caused by the cause. Since the intermediate transfer belt 35 is cleaned before application, the application function of the brush roller 62 can maintain its performance over a long period of time. Further, since the cleaning blade 66 and the lubricant uniformizing blade 67 are made of rubber which is an elastic body, the intermediate transfer belt 35 is driven while the cleaning blade 66 and the lubricant uniformizing blade 67 are in contact with each other. However, the surface of the intermediate transfer belt 35 is not damaged.

  FIG. 7 is a partially enlarged view showing the vicinity of a lubricant application portion of an image forming apparatus according to a modification of the present embodiment.

  As described above, the toner to be used is becoming the mainstream of small diameter, narrow particle size distribution and spheroidization (true sphere) by polymerized toner. However, as described above, these toners may make it difficult to clean the surface of the image carrier. Therefore, it is necessary to increase the contact pressure of the cleaning blade more than before. However, there is a high possibility that the edge of the cleaning blade is chipped due to a local shearing force generated by increasing the contact pressure. Of course, if the cleaning blade is damaged, the ability to remove residual toner is reduced, which may cause an abnormal image. Next, a solution for this problem will be described.

  Referring to FIG. 7, the lubricant application portion 60 </ b> A for applying the lubricant to the intermediate transfer belt 35 in the image forming apparatus 30 is partially enlarged. This lubricant application part 60A is provided in the belt cleaning device 40 shown in FIG. 3, and roughly speaking, the intermediate transfer belt 35, the support roller 71, the first opposing member 72, the second opposing member 73, The curved roller 74, the solid lubricant 61, the brush roller 62, the lubricant holding member 63, the pressure spring 64, the cleaning blade 66, and the second blade 75 are included. The parts described above in FIG. 7 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The lubricant application part 60A shown in FIG. 7 has a great feature that the second blade 75 is provided.

  The second blade 75 is provided downstream of the cleaning blade 66 and the brush roller 62 in the moving direction of the intermediate transfer belt 35. The second blade 75 serves as a second cleaning unit that complements the cleaning of residual toner on the surface of the intermediate transfer belt 35 by the cleaning blade 66. That is, even if the cleaning blade 66 is chipped or wear increases, the cleaning performance is assisted by the second blade 75 even if the cleaning performance cannot be maintained. The second blade 75 is made of rubber which is an elastic body. As a modification of the second blade 75, it is also possible to use a cleaning brush or the like.

  Further, if the above-described lubricant uniformizing means and the second cleaning means are the same, the number of parts can be reduced and the cost can be reduced. As the method, a second blade 75 is installed as a cleaning and lubricant uniformizing blade on the downstream side of the brush roller 62 in the moving direction of the intermediate transfer belt 35. Then, the lubricant is made uniform by the second blade 75, and at the same time, if the residual toner cannot be completely cleaned by the cleaning blade 66, the residual toner is removed. The contact method of the second blade 75 at that time can be either trailing or counter.

  In general, a counter blade method is often used as a blade contact method because of its excellent cleaning property. Here, when the cleaning blade 66 and the second blade 75 as the two cleaning means are both counter blades, the linear pressure per unit length of the cleaning blade 66 on the image carrier is A, and the image of the second blade 75 When the linear pressure per unit length to the carrier is B, it is preferable to have a linear pressure relationship in which A is B or more. There are two reasons for this. First, since the residual toner is removed by the cleaning blade 66 in a normal state, the cleaning blade 66 sets conditions with priority on the cleaning performance. On the other hand, the second blade 75 removes toner only when the cleaning blade 66 has not been able to remove it. Therefore, the cleaning performance as high as that of the cleaning blade 66 that is always exposed to the residual toner is not required. Therefore, the linear pressure of the second blade 75 can be lower than that of the cleaning blade 66. Another reason is that the higher the linear pressure of the blade, the faster the blade edge wears. Therefore, it is preferable to slow the wear of the second blade as a backup in order to extend the life. From the above two points, it is better to set the relationship of linear pressure that A is B or more. As an example, the linear pressure of the first blade is set to 0.27 (N / cm), and the linear pressure of the second blade is set to 0.20 (N / cm).

  As already described, the configuration in which the cleaning is performed on the upstream side in the moving direction of the intermediate transfer belt 35 of the brush roller 62 to which the lubricant is applied and the lubricant is made uniform on the downstream side is only applicable to the intermediate transfer belt 35. It is also provided for the photoconductor. Therefore, a brush roller for applying lubricant, a blade for cleaning, and a blade for uniformizing the lubricant (also serving as a cleaning blade) are also provided in the photoconductor cleaning unit. It is done. As a result, the same effect as that of the intermediate transfer belt can be obtained for the photosensitive member.

  In this embodiment, the surface of the intermediate transfer belt is cleaned using a cleaning blade. However, instead of the cleaning blade, a cleaning brush in which a bias is applied to a conductive brush having a medium resistance to a low resistance may be used. Good.

  The above-mentioned toner having a small particle size and a sharp particle size distribution can greatly improve the image quality, but on the other hand, the adhesion force to the surface of an image carrier such as a photosensitive member or an intermediate transfer belt increases and remains. Prone to toner. Therefore, although it becomes difficult to clean the surface of the image carrier, according to this embodiment, the residual toner is more reliably cleaned from the surface of the image carrier, and the frictional force between the surface of the image carrier and the toner is reduced. A lubricant for reducing the size can be uniformly applied to the surface of the image carrier. As a result, it is possible to provide an image forming apparatus capable of obtaining a good transfer image free from abnormal images such as insect bites, image blurs, and blurs in the transfer image.

It is the elements on larger scale near the lubricant application part which has the composition of cleaning after application. It is the elements on larger scale near the lubricant application part which has the composition of application after cleaning. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a schematic diagram illustrating a shape factor SF-1 and a shape factor SF-2 that are coefficients indicating the toner shape used in the image forming apparatus according to the present exemplary embodiment. It is a schematic diagram of a toner shape used in the image forming apparatus of the present embodiment. FIG. 3 is a partially enlarged view showing the vicinity of a lubricant application portion of the image forming apparatus according to the present exemplary embodiment. It is the elements on larger scale which show the lubricant application part vicinity of the image forming apparatus of the modification of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Coating belt 12 Coating brush 13 Cleaning blade 14 Lubricant 15 Support roller 16 Opposing member 17 Curved roller 30 Image forming apparatus 31 Apparatus main body 32 Paper feed table 33 Scanner 34 Automatic document feeder 35 Intermediate transfer belt 36 Drive rollers 37, 38 Support roller 39 Curved roller 40 Belt cleaning device 41 Image forming unit 42 Exposure device 43 Fixing device 44 Transfer paper 45 Sheet reversing device 46 Paper feed roller 47 Paper feed cassette 48 Registration roller 49 Secondary transfer roller 50 Paper discharge tray 51 Switching claw 60 , 60A Lubricant application unit 61 Solid lubricant 62 Brush roller 63 Lubricant holding member 64 Pressure spring 65 Device housing 66 Cleaning blade 67 Lubricant equalizing blade 71 Support roller 72 First opposing member 73 Second opposing member 74 Curved roller 7 5 Second blade 100 Toner

Claims (12)

In an image forming apparatus having a toner carrier for carrying toner and forming an image with the toner,
Lubricant application means for applying a lubricant to the surface of the toner carrier;
Cleaning means for cleaning the surface of the toner carrier, provided upstream of the lubricant carrier in the rotational direction of the toner carrier;
And a lubricant smoothing means for smoothing the lubricant applied to the surface of the toner carrier, provided downstream of the lubricant carrier in the rotation direction of the toner carrier. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the lubricant smoothing unit includes a blade.   The image forming apparatus according to claim 2, wherein the blade is an elastic body. In an image forming apparatus having a toner carrier for carrying toner and forming an image with the toner,
Lubricant application means for applying a lubricant to the surface of the toner carrier;
A first cleaning means for cleaning the surface of the toner carrier provided on the upstream side in the rotational direction of the toner carrier relative to the lubricant application means;
An image forming apparatus comprising: a second cleaning unit for cleaning the surface of the toner carrier provided on the downstream side in the rotation direction of the toner carrier relative to the lubricant application unit.   The image forming apparatus according to claim 4, wherein the first cleaning unit includes a first blade, and the second cleaning unit includes a second blade.   The image forming apparatus according to claim 5, wherein the first and second blades are elastic bodies.   The linear pressure on the toner carrier per unit length of the first blade is equal to or higher than the linear pressure on the toner carrier per unit length of the second blade. The image forming apparatus according to 5 or 6.   The second cleaning unit is a unit that smoothes the lubricant applied to the surface of the toner carrier and cleans the surface of the toner carrier. The image forming apparatus described in the item.   The volume average particle diameter of the toner is 3 μm or more and 8 μm or less, and the ratio of the volume average particle diameter of the toner to the number average particle diameter of the toner is 1.00 or more and 1.40 or less. The image forming apparatus according to any one of claims 1 to 8.   The shape factor SF-1 of the toner is 100 or more and 180 or less, and the shape factor SF-2 of the toner is 100 or more and 180 or less. The image forming apparatus described.   The toner is produced by crosslinking and / or stretching reaction of a toner composition containing at least an isocyanate group-containing polyester prepolymer, polyester, colorant, and release agent in an aqueous medium. Item 11. The image forming apparatus according to any one of Items 1 to 10.   The toner has a longest first axis among the toner axes, a longest second axis perpendicular to the first axis, and a perpendicular to the first and second axes. A third axis, and a ratio of a length of the second axis to a length of the first axis is not less than 0.5 and not more than 1.0, and a length of the second axis 12. The image forming apparatus according to claim 1, wherein the ratio of the length of the third axis to the axis is 0.7 or more and 1.0 or less.

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