JP2009098276A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which the degradation of image quality caused by biased abrasion of the surface of a photoreceptor is suppressed. <P>SOLUTION: The image forming apparatus includes: the photoreceptor whose surface is electrified; an image forming section which forms an electrostatic latent image on the electrified photoreceptor and develops the electrostatic latent image by a developer including toner, abrasives and a fluidizer, to form a developed image on the photoreceptor; a transfer section which transfers the developed image on the photoreceptor to a body to be transferred; a cleaning member which comes into contact with the surface of the photoreceptor after transfer; and a colorless toner supply section which is arranged on the downstream side from the image forming section and on the upstream side from the cleaning section, in the rotational direction of the photoreceptor and supplies colorless toner including the fluidizer to the area other than the area of the surface of the photoreceptor, where the electrostatic latent image is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on a recording medium by transferring and fixing the developed image obtained by developing the electrostatic latent image with a developer containing toner onto the recording medium.

  Conventionally, an electrostatic latent image is formed on a charged photosensitive member, and the electrostatic latent image is developed with a developer containing toner to obtain a developed image. The developed image is recorded on a recording medium. An image forming apparatus is known that forms an image composed of a fixed image on this recording medium by transferring and fixing to the recording medium.

  Further, the image forming apparatus as described above includes a type that cleans residual toner remaining on the surface of the photosensitive member by bringing a blade made of rubber or the like into contact with the photosensitive member after transfer.

  In the image forming apparatus of the type described above, if a predetermined image is continuously formed, only the portion where the developed image is continuously formed on the surface of the photoconductor may be worn and adversely affect the image quality. is there.

  This is because the image forming apparatus of the type described above usually uses a developer containing a polishing agent such as cerium oxide and toner, and the blade scrapes off the toner adhering to the surface of the photoreceptor. The toner remaining in the portion where the developed image is held is obtained by retaining the abrasive together with the toner in the toner reservoir formed between the blade and the surface of the photoreceptor and polishing the surface of the photoreceptor. In addition, the amount of the abrasive is large, and the polishing of the portion proceeds more than the portion where the toner image is not held, and as a result, it becomes easy to wear.

  Therefore, a proposal has been made to prevent uneven wear on the surface of the photoconductor by developing a portion of the photoconductor surface where the toner image is not formed with a transparent toner (see Patent Document 1).

  Incidentally, in recent years, due to a demand for power saving, low-temperature fixing toner capable of melting the toner even when the fixing temperature is relatively low has been used.

However, since the low-temperature fixing toner has a high viscosity, the fluidity is likely to deteriorate. In actual use, it is necessary to include a large amount of a fluidizing agent such as silica in the developer in order to improve the fluidity of the toner.
JP 2005-031197 A

  When a developer containing a low-temperature fixing toner is employed in the image forming apparatus of the type described above, and a predetermined image is continuously formed, the surface of the photoreceptor is compared with a case where a developer containing a conventional type of toner is employed. There was a phenomenon in which wear of parts other than the part where the toner image was formed intensified.

  In view of the above circumstances, an object of the present invention is to provide an image forming apparatus in which deterioration in image quality due to uneven wear on the surface of a photoreceptor is suppressed.

In order to achieve the above object, an image forming apparatus of the present invention comprises:
A photoreceptor having a charged surface;
An electrostatic latent image is formed on the charged photoreceptor, and the electrostatic latent image is developed in a developer containing toner, an abrasive, and a fluidizing agent, whereby a developed image is formed on the photoreceptor. An image forming unit for forming
A transfer portion for transferring the developed image on the photoreceptor onto the transfer target;
A cleaning member in contact with the surface of the photoreceptor after the transfer;
It is arranged downstream of the image forming unit and upstream of the cleaning unit in the rotation direction of the photoconductor, and flows to a region other than the region where the electrostatic latent image is formed on the surface of the photoconductor. And a colorless toner supply unit for supplying colorless toner containing an agent.

  According to the present invention, the wear on the surface of the photoconductor also varies depending on the content ratio of the fluidizing agent and the abrasive in the toner reservoir, and the wear is promoted in a portion where the ratio of the fluidizing agent is small with respect to the abrasive. This is based on what the present inventors have found. The fluidizing agent tends to adhere to the toner from the beginning, and this tendency becomes even more conspicuous by embedding in the toner surface and the like in the low-viscosity fixing toner having high viscosity. On the other hand, the abrasive in the developer does not adhere to the toner surface, and the distribution density on the surface of the photoreceptor is almost constant regardless of the location where the developed image is formed. As a result, in the toner reservoir, the ratio of the abrasive other than the portion where the developed image is formed becomes higher in the portion where the developed image is formed and the portion other than that. In the image forming apparatus of the present invention, the fluidizing agent is supplied to the area on the surface of the photoreceptor where the electrostatic latent image is not formed by the colorless toner supply unit. Thereby, the ratio of the abrasive | polishing agent with respect to a fluidizing agent in the area | region where the electrostatic latent image was not formed can be reduced. Therefore, according to the image forming apparatus of the present invention, it is possible to suppress deterioration in image quality due to uneven wear of the photoreceptor.

Here, it is preferable that the image forming unit develops an electrostatic latent image with a toner having a storage elastic modulus at 40 ° C. of 1 × 10 ⁷ Pa or more and 6 × 10 ⁸ Pa or less.

  If the toner stored in the image forming unit is a so-called low-temperature fixing toner having a high viscosity, the amount of fluidizing agent supplied to the area where the electrostatic latent image is formed is reduced. If the storage elastic modulus at 40 ° C. of the toner to be used has a so-called low-temperature fixability, this ratio is relative to the ratio of the so-called fluidizing agent and abrasive to the background portion where no image is formed. Therefore, the effect of suppressing deterioration in image quality due to uneven wear of the photosensitive member becomes remarkable.

  It is also a preferable aspect that the colorless toner supply unit supplies silica as the fluidizing agent.

  By using silica as a fluidizing agent, it is possible to more easily realize uneven wear suppression of the present invention.

Here, the image forming unit forms an electrostatic latent image having a predetermined polarity on the surface of the photoconductor, and the electrostatic latent image formed on the surface of the photoconductor includes toner having a polarity opposite to the predetermined polarity. Developing with this toner in the developer,
It is preferable that the colorless toner supply unit supplies the fluidizing agent containing toner having the same polarity as the predetermined polarity.

  By supplying a fluidizing agent that easily flocculates alone in such a form containing toner, appropriate mixing with the abrasive can be realized, and the polarity of this toner is set to be opposite to that of the electrostatic latent image. By doing so, the colorless toner containing the fluidizing agent can be reliably supplied to the area where the electrostatic latent image is not formed.

    As described above, even when the colorless toner supply unit supplies the fluidizing agent to the area where the electrostatic latent image is not formed before the transfer unit, the toner coated with the fluidizing agent is used. If the toner is colorless, even if a part of the colorless toner is transferred to the transfer target when it passes through the transfer portion, the image quality can be prevented from being adversely affected.

  According to the image forming apparatus of the present invention, it is possible to suppress deterioration in image quality due to uneven wear of the photoreceptor.

  Hereinafter, embodiments of the image forming apparatus of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a printer dedicated to monochrome images.

  The printer 1 shown in FIG. 1 is based on a photoconductor 10 that rotates in the direction of an arrow A and holds an image on the surface, a charger 11 that applies a charge to the surface of the photoconductor, and image data transmitted from the outside. An exposure device 12 that generates exposure light, a developing roller 131 that rotates in opposition to the photosensitive member 10, a developing device 13 that stores a developer containing toner, a paper cassette 16 that stores recording paper, and a paper A paper transport device 17 that pulls out and transports the recording paper from the cassette 16, a transfer roll 14 that transfers the toner image held on the surface of the photoreceptor 10 onto the recording paper transported in the direction of arrow B, and recording And a fixing device 15 for fixing the toner image on the recording paper by heating the toner image on the paper. The printer 1 is a first embodiment of the image forming apparatus of the present invention.

  The surface of the photoreceptor 10 is charged with a negative polarity by the charger 11, and the portion of the surface charged with the negative polarity that has been exposed to the exposure light from the exposure device 12 is on the positive side with respect to the developing bias. Is charged.

The developing unit 13 includes a low-temperature fixing toner having a storage elastic modulus of 1 × 10 ⁸ Pa at 40 ° C., cerium oxide as an abrasive for polishing the surface of the photoreceptor 10, and a fluidizing agent for increasing the fluidity of the toner. A developer containing a magnetic carrier that is a certain silica and a magnetic particle that is magnetized in a magnetic field and is a charge-giving particle that charges the toner by friction with the toner is accommodated in the developer 13. The developer is stirred, and the toner and the magnetic carrier are rubbed by the stirring. Due to this friction, the toner is negatively charged and the magnetic carrier is positively charged. For this reason, in the developer, the toner is electrostatically attached to the magnetic carrier, and these are naturally integrated.

  The developing roller 131 of the developing device 13 includes a sleeve and a magnet roll to which a negative-polarity bias is applied although not shown in the figure, and a magnetic carrier is provided on the surface of the rotating sleeve by the magnetic force of the magnet roll. The developer is held on the developing roll 131 and is conveyed to the developing region 130a formed between the photosensitive member 10 and the developer.

  A positive voltage having a polarity opposite to the polarity of the toner forming the toner image is applied to the transfer roll 14.

  In the printer 1 shown in FIG. 1, after a negative polarity charge is applied to the surface of the photoconductor 10 rotating in the direction of arrow A by the charger 11, exposure light based on image data transmitted from the outside is exposed. The electrostatic latent image having a positive polarity with respect to the developing bias is formed by irradiation of the developing device 12, and the developer held on the surface of the developing roll 131 of the developing device 13 and carried to the developing position 130 a is transferred to the photosensitive member 10. The electrostatic latent image is separated from the magnetic carrier by the electric field generated between the positive electrostatic latent image and the negative developing roller 131 with respect to the developing bias formed on the surface, and is attached to the electrostatic latent image. Development is performed. The negative toner image obtained by this development is electrostatically attracted by the positive transfer roll 14 onto the recording paper that is drawn from the paper cassette 16 by the paper transport device 17 and transported in the direction of arrow B. Then, the development image on the recording paper is heated by the fixing device 15 so that the development image is fixed on the recording paper to form an image. In the printer 1, the toner remaining on the surface of the photoconductor 10 after the developed image held on the surface of the photoconductor 10 is transferred onto the recording paper by the transfer roll 14 is used as a rubber blade on the surface of the photoconductor 10. 18 is touching and scratching. As a result, a toner reservoir in which toner is blocked is formed in the vicinity of the contact portion between the blade 18 and the photosensitive member 10. In addition to the residual toner, the toner reservoir contains cerium oxide as an abrasive. Silica, which is a fluidizing agent, is contained, and the surface of the photoreceptor 10 is polished by the toner reservoir.

By the way, the toner having a storage elastic modulus of 1 × 10 ⁸ Pa at 40 ° C. used in the printer 1 can be melted at a low temperature in order to reduce power consumption in the fixing device 15. Therefore, more silica is required as a fluidizing agent than conventional toners, and silica is more easily adhered to the toner than in the past. On the other hand, most of the abrasive cerium oxide exists in a free form in the developer regardless of the viscosity of the toner. Therefore, the portion of the toner pool corresponding to the electrostatic latent image region where the electrostatic latent image is formed and the portion corresponding to the other background region are fluidized to the portion corresponding to the electrostatic latent image region. While the agent is concentrated, there is almost no difference in the distribution density of the abrasive between the portion corresponding to the electrostatic latent image region and the portion corresponding to the background region, and the fluidizing agent in the portion corresponding to the background region The ratio of the abrasive to is higher than the ratio of the abrasive to the fluidizing agent in the portion corresponding to the electrostatic latent image region. For this reason, in a printer using low-temperature fixing toner, for example, when the same image is repeatedly formed, the degree of wear is extremely different between the electrostatic latent image region and the background region on the surface of the photoconductor. The shortening of product life is a problem.

  Therefore, the printer 1 is provided with a colorless toner supplier 19 which is disposed between the developing unit 13 and the transfer roll 14 and supplies silica as a fluidizing agent to the background area on the surface of the photoreceptor in a dispersed manner. Is provided.

In the developing device 13 described above, the contained toner is charged to a negative polarity by friction with a magnetic carrier. In this colorless toner supply device 19, a silica having a substance having a quaternary ammonium salt structure attached to its surface is used. By stirring a colorless toner having a storage elastic modulus at 40 ° C. of 1 × 10 ⁸ Pa and a developer containing a magnetic carrier, the colorless toner is positively charged and electrostatically adheres to the magnetic carrier. ing.

  The colorless toner supply device 19 is also provided with a developing roller 191 having the same configuration as the developing roller 131 of the developing device 13, and the developer is held on the surface of the developing roller 191 by the same mechanism as that in the developing device 13. The positive-colorless colorless toner in the developer thus transported to the developing position 190a is relatively less than the negative-polarity background area formed on the surface of the photoreceptor 10 and the negative-polarity background area. The magnetic field is separated from the magnetic carrier by the electric field generated between the developing roll having a high potential and adheres to the background area.

  As a result, the fluidizing agent is supplied to the background region where the distribution density of the fluidizing agent is smaller than that of the electrostatic latent image region, and the ratio of the abrasive to the fluidizing agent in the background region is reduced. The extreme difference in wear between the area and the background area is alleviated, and the life of the photoreceptor can be extended.

  Here, about the silica accommodated in the developing device 13, 100 parts of AEROSIL 380 (manufactured by Nippon Aerosil Co., Ltd., 7 nm) and 100 parts of a toluene solution containing 30 parts of hexamethyldisilazane are placed in an evaporator and mixed for 10 minutes. Thereafter, toluene was distilled off under reduced pressure, and this was taken out, mixed at 120 ° C. for 60 minutes at normal pressure, and then cooled to obtain. The colorless toner supplier 19 includes a substance having a quaternary ammonium salt structure on the surface of silica obtained by the same production method as described above (in place of hexamethyldisilazane, 3 aminopropyltriethoxysilane). Is stored in the same way.

In addition, a method for producing toner stored in the developing device 13 of the printer 1 and having a storage elastic modulus of 1 × 10 ⁸ Pa at 40 ° C. will be described.

This toner has a crystalline resin acid value of 5 to 50 mg KOH / g, an amorphous resin acid value of 10 to 50 mg KOH / g, a crystalline resin melting point of 50 to 100 ° C. according to ASTM D3418-8, and The weight average molecular weight (Mw) is 8,000 to 35,000, the glass transition temperature (Tg) of the amorphous resin determined in accordance with ASTM D3418-8 is 50 to 65 ° C., and the weight average molecular weight (Mw) is It is preferable that the ratio by weight of the crystalline resin and the amorphous resin is 5/95 to 40/60.
-Crystalline resin-
Here, the “crystalline polyester resin” refers to a resin having a clear endothermic peak rather than a stepwise endothermic amount change in differential scanning weight measurement (DSC). Here, the “crystallinity” used in the electrostatic charge developing toner means that the DSC curve has a clear endothermic peak in differential scanning calorimetry (DSC). It means that an endothermic peak when measured at 10 ° C./min occurs and then returns to the baseline of the DSC curve.

  Specifically, the crystalline resin is more preferably an aliphatic crystalline polyester resin having an appropriate melting point and an alkyl group having 6 or more carbon atoms. The polyester resin having an alkyl group having 6 or more carbon atoms can be obtained by using a polymerizable monomer having an alkyl group having 6 or more carbon atoms in a polyvalent carboxylic acid or polyhydric alcohol, such as dodecenyl succinic acid. However, the present invention is not limited to this.

  Examples of the polyvalent carboxylic acids used in the production of the resin used in the toner include aromatics such as terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and diphenic acid. Aromatic dicarboxylic acids, aromatic oxycarboxylic acids such as p-oxybenzoic acid, p- (hydroxyethoxy) benzoic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, etc. Aliphatic dicarboxylic acid, fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, hexahydrophthalic acid, tetrahydrophthalic acid, dimer acid, trimer acid, hydrogenated dimer acid, cyclohexanedicarboxylic acid, cyclohexene dicarboxylic acid, etc. Unsaturated aliphatic and alicyclic dicarboxylic acids, etc. Also be used other trimellitic acid as a polycarboxylic acid, trimesic acid, and the like trivalent or higher polyvalent carboxylic acids such as pyromellitic acid.

  Examples of the polyhydric alcohol used for the production of the resin include aliphatic polyhydric alcohols, alicyclic polyhydric alcohols, aromatic polyhydric alcohols and the like. Aliphatic polyhydric alcohols include ethylene glycol, propylene glycol, 1,3-propanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, Ring opening of lactones such as neopentyl glycol, diethylene glycol, dipropylene glycol, dimethylol heptane, 2,2,4-trimethyl-1,3-pentanediol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ε-caprolactone Examples include aliphatic diols such as lactone-based polyester polyols obtained by polymerization, triols such as trimethylolethane, trimethylolpropane, glycerin, and pentaerythritol, and tetraols.

  Alicyclic polyhydric alcohols include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, spiroglycol, hydrogenated bisphenol A, ethylene oxide adduct and propylene oxide adduct of hydrogenated bisphenol A, tricyclodecane Examples include diol, tricyclodecane dimethanol, dimer diol, hydrogenated dimer diol and the like.

  As aromatic polyhydric alcohols, para-xylene glycol, meta-xylene glycol, ortho-xylene glycol, 1,4-phenylene glycol, ethylene oxide adduct of 1,4-phenylene glycol, bisphenol A, ethylene oxide adduct of bisphenol A and Examples thereof include propylene oxide adducts.

  A monofunctional monomer may be introduced into the polyester resin for the purpose of blocking the polar group at the end of the resin and improving the environmental stability of the toner charging characteristics. Monofunctional monomers include benzoic acid, chlorobenzoic acid, bromobenzoic acid, parahydroxybenzoic acid, sulfobenzoic acid monoammonium salt, sulfobenzoic acid monosodium salt, cyclohexylaminocarbonylbenzoic acid, n-dodecylaminocarbonylbenzoic acid Acid, tertiary butylbenzoic acid, naphthalenecarboxylic acid, 4-methylbenzoic acid, 3-methylbenzoic acid, salicylic acid, thiosalicylic acid, phenylacetic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, octanecarboxylic acid, lauric acid, stearyl Monocarboxylic acids such as acids and lower alkyl esters thereof, or monoalcohols such as aliphatic alcohols, aromatic alcohols, and alicyclic alcohols can be used.

  The method for producing the crystalline resin is not particularly limited and can be produced by a general polyester polymerization method in which an acid component and an alcohol component are reacted. Examples thereof include direct polycondensation and transesterification. Produced separately depending on the type of monomer.

  The crystalline resin can be produced at a polymerization temperature of 180 to 230 ° C., and the reaction system is reduced in pressure as necessary, and the reaction is carried out while removing water and alcohol generated during condensation. When the monomer is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added as a solubilizer and dissolved. In the polycondensation reaction, the dissolution auxiliary solvent is distilled off. In the case where a monomer having poor compatibility exists in the copolymerization reaction, it is preferable that the monomer having poor compatibility and the monomer and the acid or alcohol to be polycondensed are condensed in advance and then polycondensed together with the main component.

  Catalysts that can be used in the production of crystalline resins include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metal compounds such as zinc, manganese, antimony, titanium, tin, zirconium, and germanium A phosphorous acid compound, a phosphoric acid compound, an amine compound, etc., specifically, the following compounds are mentioned.

  For example, sodium acetate, sodium carbonate, lithium acetate, lithium carbonate, calcium acetate, calcium stearate, magnesium acetate, zinc acetate, zinc stearate, zinc naphthenate, zinc chloride, manganese acetate, manganese naphthenate, titanium tetraethoxide, titanium Tetrapropoxide, titanium tetraisoproxide, titanium tetrabutoxide, antimony trioxide, triphenylantimony, tributylantimony, tin formate, tin oxalate, tetraphenyltin, dibutyltin dichloride, dibutyltin oxide, diphenyltin oxide, zirconium tetrabutoxide, naphthenic acid Zirconium, zirconyl carbonate, zirconyl acetate, zirconyl stearate, zirconyl octylate, germanium oxide, triphenyl Sufaito, tris (2, 4-t-butylphenyl) phosphite, ethyltriphenylphosphonium bromide, triethylamine, compounds such as triphenyl amine. The amount of such a catalyst added is preferably 0.01 to 1.00% by weight based on the total amount of raw materials.

  As melting | fusing point of crystalline resin, Preferably it is 50-100 degreeC, More preferably, it is 60-100 degreeC. When the melting point is lower than 50 ° C., the storage stability of the toner and the storage stability of the toner image after fixing may become a problem. When the melting point is higher than 100 ° C., sufficient low-temperature fixing cannot be obtained as compared with the conventional toner. There is a case.

  In addition, the crystalline resin may show a plurality of melting peaks, but here, the melting point is the maximum peak.

  Furthermore, for example, DSC-7 manufactured by Perkin Elmer can be used for measurement of the resin melting point. The temperature correction of the detection part of this apparatus can be similarly performed by measuring the glass transition point of the resin using the melting points of indium and zinc.

  The crystalline resin used for the toner has a weight average molecular weight (Mw) of 8,000 to 35,000 as measured by gel permeation chromatography (GPC) method in which tetrahydrofuran (THF) is soluble, preferably Is 10,000 to 25,000. When the weight average molecular weight is less than 8,000, the compatibility with the amorphous resin or the release agent proceeds, and plasticity may occur. On the other hand, if it exceeds 35,000, the viscosity at the time of melting the toner increases, and the fixability and image glossiness may be impaired. Here, the molecular weight of the resin was measured with a THF solvent using a TSO gel GPC / HLC-9120, a Tosoh column “TSKgel SuperHM-M” (15 cm), and a monodisperse polystyrene standard sample. The molecular weight was calculated using the prepared molecular weight calibration curve. The same measurement was performed for the non-crystalline polyester resin described later.

  The toner preferably has a melting point (mp) measured in accordance with ASTM D3418-8 of crystalline resin of 50 to 100 ° C. When the melting point is less than 50 ° C., the thermal stability of the toner is lowered, and when it exceeds 100 ° C., the image glossiness at the time of toner fixing is lowered.

The acid value of the crystalline resin (the number of mg of KOH required to neutralize 1 g of resin) is controlled to 5 to 50 mg KOH / g. When the acid value is less than 5 mgKOH / g, the crystalline resin particles form aggregates, which makes it difficult to form a structure with the release agent, and the crystalline resin particles exist independently in the toner. Alternatively, it may grow large and be exposed on the toner surface, which is not preferable from the viewpoint of toner fluidity and chargeability. Further, when the acid value exceeds 50 mgKOH / g, it may be difficult to encapsulate the toner.
-Amorphous polyester resin-
The amorphous polyester resin is obtained by polycondensation of the above-described polyvalent carboxylic acids and polyhydric alcohols using the above catalyst.

  The amorphous resin can be produced by subjecting the polyhydric alcohol and polyhydric carboxylic acid to a condensation reaction according to a conventional method. For example, the above polyhydric alcohol and polyvalent carboxylic acid, if necessary, a catalyst, and blended in a reaction vessel equipped with a thermometer, a stirrer, a flow-down condenser, and in the presence of an inert gas (such as nitrogen gas), Heat at 150 to 250 ° C. to continuously remove by-product low-molecular compounds out of the reaction system, stop the reaction when a predetermined acid value is reached, cool, and obtain the desired reactant Can be manufactured.

  The glass transition temperature of the non-crystalline polyester resin used in this toner is required to be 50 ° C. or higher when determined in accordance with ASTM D3418-8, and more preferably 55 ° C. or higher, or even 60 ° C. As mentioned above, it is preferable that it is less than 65 degreeC. When the glass transition temperature is less than 50 ° C., there is a tendency to aggregate during handling or storage, which may cause a problem in storage stability. On the other hand, when the temperature is 65 ° C. or higher, fixability may be deteriorated.

  The softening point of the amorphous resin used for this toner is preferably in the range of 60 to 90 ° C. In the toner in which the softening temperature of the resin is suppressed to less than 60 ° C., the toner tends to aggregate during handling or storage, and the fluidity may be greatly deteriorated particularly during long-time storage. When the softening point exceeds 90 ° C., the fixability may be hindered. Further, since it is necessary to heat the fixing roll to a high temperature, the material of the fixing roll and the material of the base material to be copied are limited.

  The amorphous polyester resin used in this toner has a weight average molecular weight (Mw) of 20,000 to 50,000 as measured by a gel permeation chromatography (GPC) method in which tetrahydrofuran (THF) is soluble. Yes, preferably 25,000 to 50,000. When the weight average molecular weight is less than 25,000, not only the heat storage property of the toner is lowered, but also the strength of the fixed image is lowered. On the other hand, if it exceeds 50,000, the fixing property is deteriorated and the image gloss is also lowered.

  The acid value of the amorphous polyester resin is preferably 10 to 50 mgKOH / g. When the acid value is less than 10 mgKOH / g, the particle size growth of the aggregates during the production of the toner is accelerated, and there may be a problem that the particle size distribution of the resulting toner is expanded. If the acid value exceeds 50 mgKOH / g, the difference between the acid value of the crystalline resin and the release agent increases, and therefore, only the aggregation with the crystalline resin and the release agent may proceed, and the fixing property may be increased. There is a problem that the toner changes between the toner particles. The acid value of the non-crystalline polyester resin can be adjusted by controlling the carboxyl group at the end of the polyester by the blending ratio and reaction rate of the raw polyhydric carboxylic acid and polyhydric alcohol. Or what has a carboxyl group in the principal chain of polyester is obtained by using trimellitic anhydride as a polyvalent carboxylic acid component.

  In this toner, the weight ratio of the crystalline resin to the amorphous resin is 5/95 to 40/60, and if the ratio of the amorphous resin is less than 60%, good fixing characteristics can be obtained, but in the fixed image. The phase separation structure becomes non-uniform, and the strength of the fixed image, particularly the scratching strength, may be reduced, and the scratch may be easily caused. On the other hand, when it exceeds 95%, sharp melting property derived from a crystalline resin may not be obtained, and plasticity may occur, and toner blocking resistance and image storage stability are maintained while ensuring good low-temperature fixability. May not be possible.

  The preparation of the crystalline resin and the amorphous resin particle dispersion can be prepared by adjusting the acid value of the resin or emulsifying and dispersing using an ionic surfactant or the like.

  In addition, in the case of resins prepared by other methods, if the resin is soluble in an oily solvent with relatively low solubility in water, the resin is dissolved in those solvents to dissolve the ionic surfactant or polymer electrolyte in water. At the same time, the particles are dispersed in water by a disperser such as a homogenizer, and then heated or decompressed to evaporate the solvent, whereby a resin particle dispersion can be prepared. Alternatively, a resin particle dispersion may be prepared by adding a surfactant to the resin and emulsifying and dispersing in water with a disperser such as a homogenizer or by a phase inversion emulsification method.

The particle diameter of the resin particle dispersion thus obtained can be measured, for example, with a laser diffraction particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.).
-Release agent-
Specific examples of the release agent used as the release agent used in this toner include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene, silicones which show a softening point upon heating; oleic acid amide, erucic acid amide, ricinoleic acid Fatty acid amides such as amides and stearamides; plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, Mineral and petroleum waxes such as microcrystalline wax and Fischer-Tropsch wax, ester waxes of higher fatty acids and higher alcohols such as stearyl stearate and behenyl behenate; butyl stearate, propyl oleate, monoste Ester waxes of higher fatty acids such as phosphate glyceride, distearate glyceride, pentaerythritol tetrabehenate and unit or polyvalent lower alcohols; diethylene glycol monostearate, dipropylene glycol distearate, distearate diglyceride, tetrastearic acid Examples include ester waxes composed of higher fatty acids such as triglycerides and polyhydric alcohol multimers; sorbitan higher fatty acid ester waxes such as sorbitan monostearate; cholesterol higher fatty acid ester waxes such as cholesteryl stearate. Here, these release agents may be used alone or in combination of two or more. Of these, those having a melting point of 40 ° C. to 120 ° C. are used, but in order to meet the recent demand for low-temperature fixability for energy saving, those having a temperature of 50 ° C. to 100 ° C. are particularly preferred. Preferably a thing of 50-80 degreeC is used.

  The addition amount of these release agents is preferably in the range of 0.5 to 30% by weight, more preferably in the range of 1 to 20% by weight, and still more preferably in the range of 5 to 15% by weight with respect to the total amount of toner. % Range. When the addition amount is less than 0.5% by weight, there is no effect of adding a release agent. When the addition amount exceeds 30% by weight, the charging property is likely to be affected, or the toner is easily destroyed inside the developing device, and the release In some cases, the mold agent is spent on the carrier, and the charge is likely to decrease.

  The volume average particle size of the wax particles in the release agent dispersion is preferably in the range of 0.1 to 0.5 μm, particularly preferably 0.1 to 0.3 μm. When the volume average particle size exceeds 0.5 μm, the toner is easily exposed to the toner surface, and the powder fluidity of the toner is deteriorated and filming on the photosensitive member and the developing member is facilitated. In addition, there is a problem that the release agent particles are not included in the coalescing step and are dropped in the coalescing step. In particular, in the case of obtaining a color toner, if the release agent particles are large, the OHP permeability is lowered due to irregular reflection, and the color reproducibility is also lowered. In addition, the said volume average particle diameter can be measured using the laser diffraction type particle size distribution measuring instrument etc. which were mentioned above, for example. When the volume average particle size is 0.1 μm or less, it is not preferable because sufficient releasability cannot be imparted to the toner.

The dispersion medium in the release agent dispersion is preferably an aqueous medium, and water, pure water, or ion exchange water is used. A surfactant is used as the dispersant. The wax dispersion used for this toner is prepared by a known dispersion method such as a media type dispersing machine such as a ball mill, a sand mill, or an attritor, a high pressure type dispersing machine such as a nanomizer, a microfluidizer, an optimizer, or a gorin. Any method and conditions may be used as long as the particle size and content as described can be satisfied.
-Colorant-
The colorant is usually present in an effective amount in the toner, for example from about 1 to about 15% by weight of the toner, desirably from about 3 to about 10% by weight. The colorant used here is not particularly limited, and a known colorant can be used and can be appropriately selected according to the purpose. One type of pigment may be used alone, or two or more types of pigments of the same type may be mixed and used. Two or more different types of pigments may be mixed and used. Specific examples of the colorant include carbon black such as furnace black, channel black, acetylene black, and thermal black.

The dispersion medium for dispersing the colorant is preferably an aqueous medium, and water, pure water, or ion exchange water is used. A surfactant is used as the dispersant. Preparation of the colorant dispersion used for this toner is, for example, a known dispersion method such as a media-type disperser such as a ball mill, a sand mill, or an attritor, or a high-pressure disperser such as a nanomizer, microfluidizer, optimizer, or gorin. As long as it can satisfy the particle size and content as described above, it may be produced by any method or condition.
<Other ingredients>
This toner contains silica for the purpose of improving fluidity, and cerium oxide is added as an abrasive for polishing and refreshing the surface of the photoreceptor.
<Toner characteristics>
The volume average particle size of the toner is preferably 3 to 10 μm, more preferably 4 to 9 μm, and more preferably 5 to 8 μm. If the particle size is too small, the productivity becomes unstable, the chargeability becomes insufficient and the developability may be lowered, and if it is too large, the resolution of the image is lowered.

  Further, this toner preferably has a volume average particle size distribution index GSDv of 1.30 or less. Further, the ratio (GSDv / GSDp) of the volume average particle size distribution index GSDv and the number average particle size distribution index GSDp is preferably 0.95 or more. When the volume distribution index GSDv exceeds 1.30, the resolution of the image may decrease, and the ratio of the volume average particle size distribution index GSDv to the number average particle size distribution index GSDp (GSDv / GSDp) is If it is less than 0.95, the toner chargeability may be reduced, the toner may be scattered or fogged, and image defects may be caused.

  Here, the toner particle size, the above-mentioned volume average particle size distribution index GSDv, and number average particle size distribution index GSDp were measured and calculated as follows. First, with respect to the divided particle size range (channel), the toner particle size distribution measured using a Coulter Multisizer II (manufactured by Beckman-Coulter) is accumulated from the smaller diameter side with respect to the divided particle size range (channel). Draw a distribution and define the particle size to be 16% cumulative as the volume average particle size D16v and the number average particle size D16p. The particle size to be 50% cumulative is the volume average particle size D50v and the number average particle The diameter is defined as D50p. Similarly, particle diameters that are 84% cumulative are defined as volume average particle diameter D84v and number average particle diameter D84p. In this case, the volume average particle size distribution index (GSDv) is defined as D84v / D16v, and the number average particle size index (GSDp) is defined as D84p / D16p. (GSDv) and number average particle size index (GSDp) can be calculated.

The charge amount of the toner is an absolute value, preferably 15 to 60 μC / g, and more preferably 20 to 50 μC / g. If the charge amount is less than 15 μC / g, background stains (fogging) are likely to occur, and if it exceeds 60 μC / g, the image density tends to decrease. The ratio of the charge amount in summer (high temperature and humidity) and the charge amount in winter (low temperature and low humidity) of this toner is preferably 0.5 to 1.5, more preferably 0.7 to 1.3. preferable. When the ratio is outside these ranges, the charging property is highly dependent on the environment, and the charging stability is poor, which is not preferable for practical use.
[Magnetic carrier]
Next, the magnetic carrier will be described.

  Examples of the magnetic carrier include the following resin-coated carriers in addition to ferrite. Examples of the core particles of the resin-coated carrier include normal iron powder and magnetite molding, and the volume average particle size is in the range of about 30 to 200 μm.

  Examples of the coating resin for the resin-coated carrier include styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, 2-acrylic acid 2- Α-methylene fatty acid monocarboxylic acids such as ethylhexyl, methyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate; nitrogen-containing acrylics such as dimethylaminoethyl methacrylate; vinyl such as acrylonitrile and methacrylonitrile Nitriles; Vinyl pyridines such as 2-vinyl pyridine and 4-vinyl pyridine; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl keto Homopolymers such as vinyl ketones such as ethylene; olefins such as ethylene and propylene; vinyl-based fluorine-containing monomers such as vinylidene fluoride, tetrafluoroethylene and hexafluoroethylene; and copolymers comprising two or more types of monomers Furthermore, silicone resins containing methyl silicone, methyl phenyl silicone, etc., polyesters containing bisphenol, glycol, etc., epoxy resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, polycarbonate resins and the like can be mentioned. These resins may be used alone or in combination of two or more. The coating amount of the coating resin is preferably in the range of about 0.1 to 10 parts by weight and more preferably in the range of 0.5 to 3.0 parts by weight with respect to 100 parts by weight of the core particles.

  For the production of the carrier, a heating kneader, a heating Henschel mixer, a UM mixer, or the like can be used. Depending on the amount of the coating resin, a heating fluidized rolling bed, a heating kiln, or the like can be used. .

This completes the description of the toner used in the printer 1. In addition, regarding the production method of the colorless toner having a storage elastic modulus of 1 × 10 ⁸ Pa at 40 ° C. accommodated in the colorless toner supplier 19 of the printer 1, the storage elastic modulus at 40 ° C. accommodated in the developing device 13 is 1 ×. Since only the coloring step in the production method of the 10 ⁸ Pa toner is omitted, the description is omitted.

  Next, a second embodiment of the image forming apparatus of the present invention will be described.

  FIG. 2 is a schematic configuration diagram of a printer dedicated to monochrome images. 2 that are the same as those shown in FIG. 1 are assigned the same reference numerals as those shown in FIG.

  The difference between the printer 2 shown in FIG. 2 and the printer 1 shown in FIG. 1 is that a colorless toner supplier 29 having the same function as the colorless toner supplier 19a provided in the printer 1 shown in FIG. Then, the direction of the arrow A of the photoconductor 10 is arranged downstream of the transfer roll 14 and upstream of the blade 18, and the development roller 291 of the colorless toner supply device 29 is connected to the colorless toner supply device of the printer 1. A developing bias that is slightly lower than the developing bias applied to the 19 developing rolls 191 is applied. The printer 2 is a second embodiment of the image forming apparatus of the present invention. In addition, the colorless toner supplier 29 provided in the printer 2 contains developer containing colorless toner as in the colorless toner supplier 19 provided in the printer 1. The developer 29 is supplied to the surface of the photosensitive member by the device 29 on the downstream side of the transfer roll 14 and does not affect the color of the toner image transferred onto the recording paper by the transfer roll 14. The toner contained in the developer contained in the colorless toner supply device 29 is not colorless and can be a colored toner. In addition, a developing bias that is slightly lower than the developing bias applied to the developing roller 191 of the colorless toner supplier 19 is applied to the developing roller 291 of the colorless toner supplier 29 in the back surface area of the photoreceptor surface. Since the potential drops slightly when passing through the transfer roll 14, if the developing bias of the developing roll 291 is the same as the developing bias of the developing roll 191, the positively charged toner is only attached to the back region. This is because the electric field strength cannot be ensured.

  The colorless toner supplier 29 of the printer 2 holds the developer on the surface of the developing roller 291 and is carried to the developing position 290a. The positive polarity colorless toner in the conveyed developer is the surface of the photoreceptor 10. The magnetic field is separated from the magnetic carrier by the electric field generated between the negative polarity background region formed on the surface and the developing roll which is negative but has a higher potential than the background region, and adheres to the background region.

  As a result, the fluidizing agent is supplied to the background area where the distribution amount of the fluidizing agent is smaller than that of the electrostatic latent image area, and the ratio of the abrasive to the fluidizing agent in the background area is reduced. An extreme difference in wear between the area and the background area is suppressed, and the life of the photoreceptor can be extended.

In the embodiment described above, the toner having a storage elastic modulus of 1 × 10 ⁸ Pa at 40 ° C. is exemplified as an example of the toner according to the present invention. However, the toner according to the present invention is at 40 ° C. The storage elastic modulus may be 1 × 10 ⁷ Pa or more and 6 × 10 ⁸ Pa or less, or the storage elastic modulus at 40 ° C. is outside the range of 1 × 10 ⁷ Pa or more and 6 × 10 ⁸ Pa or less. There may be.

  Further, in the embodiment described above, silica is taken as an example of the fluidizing agent accommodated in the image forming portion according to the present invention and the fluidizing agent accommodated in the fluidizing agent supply portion according to the present invention. However, if the fluidizing agent according to the present invention has the same mixing condition as the abrasive according to the present invention, the fluidizing agent accommodated in the image forming portion and the fluidizing agent accommodated in the fluidizing agent supply portion. The agents may be of the same type or different types.

  Next, experiments (Examples 1 to 10 and Comparative Examples 1 to 3) conducted to confirm the effects of the present invention will be described.

  Example 1 to Example 10 and Comparative Example 1 to Comparative Example 3 include the developing unit described in the above embodiment instead of the developing unit provided in the printer (DocuCenterColor 7550) manufactured by Fuji Xerox Co., Ltd. With respect to the direction of rotation of the photosensitive member, in a modified machine in which a colorless toner supply device is arranged downstream of the developing device and upstream of the transfer roll, the developer contained in the developing device and the colorless toner supply device respectively. A cycle in which one halftone image is output every 1000 output images that form a solid 1 cm wide image at the center in an environment of high temperature and high humidity (28 ° C., 80% RH) under different conditions. A 50-times running test was conducted to investigate the “occurrence of shading difference” on the halftone image. The paper H used is R paper A4 manufactured by Fuji Xerox. In addition, a solid image having a width of 1 cm is used at the center of the paper this time. However, as long as it is possible to investigate the “occurrence of light and shade difference”, the center is not necessary, and the width and the number are not limited thereto. Not too long. Note that the results shown below have the same tendency as the case where the colorless toner supply device is disposed downstream of the transfer roll and upstream of the blade with respect to the rotation direction of the photosensitive member, and the description thereof will be omitted. To do.

In Example 1, a developer containing a black toner whose storage elastic modulus at 40 ° C. is adjusted to 9 × 10 ⁶ Pa, cerium oxide as an abrasive, and silica as a fluidizing agent is contained in the developing device. The weight percentages of cerium oxide and silica with respect to the total weight of the developer contained in the developing unit are 0.55 (Wt%) and 1.73 (Wt%), respectively. Further, the colorless toner feeder contains developer containing colorless toner particles whose storage elastic modulus at 40 ° C. is adjusted to 9 × 10 ⁶ Pa and silica as a fluidizing agent. The weight percentage of silica relative to the total weight of developer contained in the feeder is 1.73 (Wt%).

In Example 2, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 1 × 10 ⁷ Pa were accommodated in the developing device, and the storage elastic modulus at 40 ° C. was stored in the colorless toner supply device at 1 × 10 ⁷ Pa. The conditions were the same as in Example 1 except that the colorless toner particles prepared in the above were accommodated.

In Example 3, the same conditions as in Example 1 were used except that the black toner particles having a storage elastic modulus of 1 × 10 ⁸ Pa at 40 ° C. described in the above embodiment were used. The black toner particles having a storage elastic modulus at 40 ° C. adjusted to 1 × 10 ⁸ Pa were prepared by the manufacturing method described in the above embodiment, and the storage elastic modulus at 40 ° C. was 1 × 10 ⁸ Pa. The colorless toner particles adjusted to have been prepared by the manufacturing method described in the above embodiment.

In Example 4, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 6 × 10 ⁸ Pa were accommodated in the developing device, and the storage elastic modulus at 40 ° C. was stored in the colorless toner supply device as 6 × 10 ⁸ Pa. The conditions were the same as in Example 1 except that the black toner particles thus adjusted were accommodated.

In Example 5, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 7 × 10 ⁸ Pa were accommodated in the developing device, and the storage elastic modulus at 40 ° C. was stored in the colorless toner supplier as 7 × 10 ⁸ Pa. The conditions were the same as in Example 1 except that the colorless toner particles prepared in the above were accommodated.

  In Example 6, the same conditions as in Example 3 were applied except that 0.1 (Wt%) of cerium oxide was added to the developer contained in the colorless toner supplier.

  In Example 7, the same conditions as in Example 3 were used except that 0.55 (Wt%) of cerium oxide was added to the developer contained in the colorless toner supplier.

In Example 8, colorless toner particles in which the storage elastic modulus at 40 ° C. was adjusted to 1 × 10 ⁷ Pa were stored in the colorless toner feeder, not the colorless toner particles having a storage elastic modulus at 40 ° C. of 1 × 10 ⁸ Pa. The conditions were the same as in Example 3 except for the above.

In Example 9, colorless toner particles in which the storage elastic modulus at 40 ° C. was adjusted to 6 × 10 ⁸ Pa were stored in the colorless toner feeder, not the colorless toner particles having a storage elastic modulus at 40 ° C. of 1 × 10 ⁸ Pa. The conditions were the same as in Example 3 except for the above.

  Comparative Example 1 is a case where silica as a fluidizing agent is omitted from the developer contained in the colorless toner supplier in Example 6.

  Comparative Example 2 is a case where the colorless toner supplier is omitted in Example 3.

The evaluation of “occurrence of density difference” on the halftone image for each of Examples 1 to 9, Comparative Example 1, and Comparative Example 2 was performed as follows.
-Occurrence of light and shade difference ◎: Very good with no light and shade up to 50,000 sheets. ○: Slight difference in density was observed on 50,000 sheets, but good. △: Acceptable range although slight difference in density was observed on 40,000 sheets. X: Notable due to significant difference in density produced at 50,000 sheets or less In these examples and comparative examples, the potential of the electrostatic latent image region on the photoreceptor is -200V, the potential of the back region is -640V, The developing bias of the developing roller of the developing device is −550V, and the developing bias of the developing roller of the colorless toner supply device is −450V.

  Table 1 shows the storage conditions (Pa) of 40 ° C. of black toner contained in the developing device, which is the setting condition in each of Examples 1 to 9, Comparative Example 1, and Comparative Example 2. ', Weight percent (Wt%) of' cerium oxide ', weight percent of' silica '(Wt%),' storage modulus (Pa) of colorless toner at 40 ° C 'contained in colorless toner supply, The weight percentage (Wt%) of 'cerium oxide', the weight percentage of 'silica' (Wt%), and the evaluation of 'occurrence of shading' in halftone images are shown.

In Example 1, in the developing device, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 9 × 10 ⁶ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) based on the total weight of the developer, While containing a developer containing silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer, the colorless toner feeder has a storage elastic modulus at 40 ° C. of 9 × 10 ⁶ Pa. The developer containing the colorless toner adjusted to 1 and the silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is supplied to the background area on the photoreceptor. And the relative proportion of abrasive in the background area is reduced. For this reason, uneven wear in the background area was reduced, and the evaluation of “occurrence of shading difference” was good as “◯”.

In Example 2, in the developing device, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 1 × 10 ⁷ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) with respect to the total weight of the developer, Whereas a developer containing silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is contained, the colorless toner feeder has a storage elastic modulus at 40 ° C. of 1 × 10 ⁷ Pa. The developer containing the colorless toner adjusted to 1 and the silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is supplied to the background area on the photoreceptor. And the relative proportion of abrasive in the background area is reduced. For this reason, uneven wear in the background area was reduced, and the evaluation of “occurrence of shading difference” was very good as “◎”.

In Example 3, in the developing device, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 1 × 10 ⁸ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) with respect to the total weight of the developer, Whereas a developer containing silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is contained, the colorless toner feeder has a storage elastic modulus at 40 ° C. of 1 × 10 ⁸ Pa. The developer containing the colorless toner adjusted to 1 and the silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is supplied to the background area on the photoreceptor. And the relative proportion of abrasive in the background area is reduced. For this reason, uneven wear in the background area was reduced, and the evaluation of “occurrence of shading difference” was very good as “◎”.

In Example 4, in the developing unit, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 6 × 10 ⁸ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) with respect to the total weight of the developer, While containing a developer containing silica having a weight percent of 1.73 (Wt%) with respect to the total weight of the developer, the colorless toner feeder has a storage elastic modulus at 40 ° C. of 6 × 10 ⁸ Pa. The developer containing the colorless toner adjusted to 1 and the silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is supplied to the background area on the photoreceptor. And the relative proportion of abrasive in the background area is reduced. For this reason, uneven wear in the background area was reduced, and the evaluation of “occurrence of shading difference” was very good as “◎”.

In Example 5, in the developing device, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 7 × 10 ⁸ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) with respect to the total weight of the developer, Whereas a developer containing silica having a weight percentage of 1.73 (Wt%) with respect to the total weight of the developer is contained, the colorless toner feeder has a storage elastic modulus at 40 ° C. of 7 × 10 ⁸ Pa. The developer containing the colorless toner adjusted to 1 and the silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is supplied to the background area on the photoreceptor. And the relative proportion of abrasive in the background area is reduced. For this reason, uneven wear in the background area was reduced, and the evaluation of “occurrence of shading difference” was good as “◯”.

In Example 6, in the developing device, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 1 × 10 ⁸ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) with respect to the total weight of the developer, Whereas a developer containing silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is contained, the colorless toner feeder has a storage elastic modulus at 40 ° C. of 1 × 10 ⁸ Pa. A colorless toner adjusted to 1, a silica having a weight percentage of 1.73 (Wt%) with respect to the total weight of the developer, and a developer containing 0.1 (Wt%) cerium oxide as an abrasive. Therefore, although the fluidizing agent is supplied to the background area and the abrasive is supplied to the surface of the photoreceptor, the ratio of the abrasive to the fluidizing agent in each of the electrostatic latent image area and the background area is The difference closes. For this reason, the evaluation of “occurrence of light and shade difference” was as good as “◯”.

In Example 7, in the developing device, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 1 × 10 ⁸ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) with respect to the total weight of the developer, Whereas a developer containing silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is contained, the colorless toner feeder has a storage elastic modulus at 40 ° C. of 1 × 10 ⁸ Pa. A developer containing a colorless toner adjusted to 1, a silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer, and 0.55 (Wt%) of cerium oxide as an abrasive. Although the fluidizing agent is supplied to the background area on the photoreceptor and the abrasive is supplied to the surface of the photoreceptor, the fluidizing agent in each of the electrostatic latent image area and the background area is provided. In the ratio of abrasive to Shrink. For this reason, the evaluation of “occurrence of light and shade difference” was within the allowable range of “Δ”.

In Example 8, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 1 × 10 ⁸ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) with respect to the total weight of the developer, and the total weight of the developer The developer containing a silica having a weight percentage of 1.73 (Wt%) with respect to the toner is contained in the colorless toner feeder, while the colorless toner feeder having a storage elastic modulus at 40 ° C. adjusted to 1 × 10 ⁷ Pa. And a developer containing silica having a weight percentage of 1.73 (Wt%) with respect to the total weight of the developer, the fluidizing agent is supplied to the background area on the photoreceptor, and the background area The relative proportion of abrasive in the lowers. For this reason, uneven wear in the background area was reduced, and the evaluation of “occurrence of shading difference” was very good as “◎”.

In Example 9, in the developing device, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 1 × 10 ⁸ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) with respect to the total weight of the developer, While containing a developer containing silica having a weight percent of 1.73 (Wt%) with respect to the total weight of the developer, the colorless toner feeder has a storage elastic modulus at 40 ° C. of 6 × 10 ⁸ Pa. The developer containing the colorless toner adjusted to 1 and the silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is supplied to the background area on the photoreceptor. And the relative proportion of abrasive in the background area is reduced. For this reason, uneven wear in the background area was reduced, and the evaluation of “occurrence of shading difference” was very good as “◎”.

In Comparative Example 1, in the developing device, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 1 × 10 ⁸ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) with respect to the total weight of the developer, Whereas a developer containing silica having a weight percentage of 1.73 (Wt%) based on the total weight of the developer is contained, the colorless toner feeder has a storage elastic modulus at 40 ° C. of 1 × 10 ⁸ Pa. By storing a developer containing colorless toner adjusted to 1 and 0.1 (Wt%) of cerium oxide, which is an abrasive, an abrasive instead of a fluidizing agent is present in the background area on the photoreceptor. By being supplied, the difference in the ratio of the abrasive to the fluidizing agent in each of the electrostatic latent image region and the background region was opened, and the evaluation of “Generation of density difference” was “×”.

In Comparative Example 2, in the developing device, black toner particles whose storage elastic modulus at 40 ° C. was adjusted to 1 × 10 ⁸ Pa, cerium oxide having a weight percentage of 0.55 (Wt%) with respect to the total weight of the developer, Only a developer containing a developer containing silica having a weight percentage of 1.73 (Wt%) with respect to the total weight of the developer, no colorless toner supply device is provided, and the evaluation of 'occurrence of density difference' is It was “×”.

  From Example 3, Example 6, Example 7, and Comparative Example 1, if the fluidizing agent is supplied from the colorless toner supply device to the back surface region of the photoreceptor, the abrasive is supplied to the back surface region. Even in this case, it was confirmed that there was an effect in suppressing uneven wear of the photoreceptor.

From Example 1 to Example 5, when the storage elastic modulus of the black toner at 40 ° C. is in the range of 1 × 10 ⁷ Pa or more and 6 × 10 ⁸ Pa or less, the effect of suppressing uneven wear of the photoreceptor is obtained. It was confirmed that it was remarkable.

  From Example 3, Example 8, and Example 9, the storage elastic modulus of the colorless toner accommodated in the colorless toner supply device and the storage elastic modulus of the black toner accommodated in the developing device are uneven wear of the photoreceptor. It was confirmed that it was unrelated to the inhibitory effect of.

FIG. 2 is a schematic configuration diagram of a printer dedicated to monochrome images. FIG. 2 is a schematic configuration diagram of a printer dedicated to monochrome images.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Image forming apparatus 10 Photoconductor 11 Charging device 12 Exposure device 13 Developing device 14 Transfer roll 15 Fixing device 16 Paper cassette 17 Paper transport device 18 Blade 19, 29 Colorless toner supply device 191, 291 Developing roll

Claims (4)

A photoreceptor having a charged surface;
An electrostatic latent image is formed on the charged photosensitive member, and the electrostatic latent image is developed with a developer containing toner, an abrasive, and a fluidizing agent, whereby a developed image is formed on the photosensitive member. An image forming unit for forming
A transfer portion for transferring the developed image on the photoreceptor onto the transfer target;
A cleaning member in contact with the surface of the photoreceptor after the transfer;
It is arranged downstream of the image forming unit and upstream of the cleaning unit in the rotation direction of the photoconductor, and flows to a region other than the region where the electrostatic latent image is formed on the surface of the photoconductor. An image forming apparatus comprising: a colorless toner supply unit that supplies colorless toner containing an agent. 2. The image forming unit develops an electrostatic latent image with a developer containing a toner having a storage elastic modulus at 40 ° C. of 1 × 10 ⁷ Pa or more and 6 × 10 ⁸ Pa or less. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the colorless toner supply unit supplies silica as the fluidizing agent. The image forming unit is developed with a developer containing toner of a predetermined polarity,
The image forming apparatus according to claim 1, wherein the colorless toner supply unit supplies toner having a polarity opposite to the predetermined polarity.

Images