JP2010085478A - Image forming method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and an image forming apparatus, which prevent an image defect, so-called "firefly", without forming any loose aggregate of toner even when the toner undergoes stress such as pressure or heat by a transport means to transport a developer from a storage container to a development container. <P>SOLUTION: The image forming method includes: a step of forming an electrostatic latent image; a development step; a transfer step; a fixing step; a toner transport step of supplying a supply toner stored in the storage container from the storage container to the development container in accordance with the amount of toner consumed by image formation; and an excess developer discharge step of discharging an excess developer which becomes surplus in the development container by toner supply at the toner transport step to the outside of the development container. A premix toner prepared by mixing toner and carrier in a certain ratio is used as the supply toner, and the premix toner contains porous particles having a particle diameter of ≤1 mm in an amount of 10-15 vol.% based on the amount of the toner. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming method and an image forming apparatus suitable for a copying machine, a facsimile, a laser printer, a direct digital plate making machine, and the like.

The image forming method includes a toner transferring step for transferring toner from a toner cartridge to a developing portion, a charging step for uniformly charging an image forming region on the surface of the electrostatic latent image carrier, and An exposure process for writing, a developing process for forming an image with toner triboelectrically charged on the electrostatic latent image carrier, and an electrostatic latent image carrier on the printing paper directly or indirectly via an intermediate transfer member After the transfer process for transferring the image on the body, the image is fixed on the printing paper. Further, the untransferred toner remaining on the electrostatic latent image carrier without being transferred onto the electrostatic latent image carrier is scraped off from the electrostatic latent image carrier by the cleaning process, and enters the next image forming process.
When a two-component developing device is employed in an electrophotographic image forming apparatus, the toner density is detected to control the mixing ratio of toner and carrier in the developing device to be constant. . For this reason, a toner container such as a toner bottle or a cartridge is provided in or near the unit having the developing device, and toner is supplied to the developer container according to the amount of toner consumed by use from the toner container. ing. In this case, transfer and replenishment of the toner from the developing container to the developing unit is performed by a stirring and conveying mechanism such as a screw or a paddle.

  Here, FIG. 1 shows a schematic diagram of a general toner transfer device (toner supply device). The toner replenishing device replenishes the developing device 201 with a developer, and includes a toner storage container 203 storing toner, means for carrying out the toner stored in the toner storage container, and a developing device. 201. These means are provided with powder pump means 202 as suction means. The powder pump unit 202 serves as a suction unit that transports toner from the toner storage container 203 and a suction unit that moves the toner transported from the toner storage container 203 to the developing device.

FIG. 2 is a cross-sectional view of the powder pump means 202. The powder pump means 202 has a suction type uniaxial eccentric powder pump 204 called a so-called Mono pump (see Patent Document 1).
The configuration of the powder pump 204 includes a rotor 205 made of an eccentric screw made of a rigid material such as metal, and a stator 206 made of an elastic body such as rubber and made of a double screw. And a holder 7 made of a resin material or the like that wraps them and forms a powder conveyance path. The stator 206 is fixedly installed on the holder 207. The rotor 205 is driven to rotate through a gear 208 and a joint 209 that are drivingly connected to a driving source.

In the powder pump 204 configured in this manner, when the rotor 205 is rotated, a strong self-suction force is generated in the pump. It can be sent out from the discharge section. In addition, air is supplied to the powder pump unit 202 from an air pump pipe (not shown), fluidization of the toner sent out by the air is promoted, and toner transfer is ensured by the powder pump 204. The suction-type powder pump 204 is actuated by transmitting the drive to the gear through a dedicated motor or a main motor and a clutch in the image forming apparatus, and the drive is controlled.
This pump has a simple structure and a small size, and does not impose a load on the toner to be transferred. Therefore, it is preferable that the pump is less deteriorated (see Patent Document 2). However, the screw pump used in this powder pump basically has a mechanism for transferring toner as an air-fuel mixture, and the toner is transferred while the contact portion of the rotor and stator rub against each other. In some cases, the toner enters the toner, and stress is applied to the toner due to frictional heat, shearing force, and pressure to form a toner agglomerate having a diameter of 0.1 mm to 1 mm.

The toner agglomerates thus formed are crushed with a certain degree of history and return to the normal toner powder state, but the history of each process of image formation is until the pulverization. Can not. Therefore, when a solid color point is formed as compared with the solid image density of a single color solid image (toner adhesion amount 0.45 mg / cm ² ) formed on the recording medium, a light color gamut is formed around the dark color point. There is a problem that an abnormal image (hereinafter, sometimes referred to as “firefly”) occurs.

Japanese Patent No. 3872506 Japanese Patent Laid-Open No. 2007-07954

  This invention is made | formed in view of this present condition, and makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, the present invention provides a so-called “firefly” which does not form a toner agglomerate and is an abnormal image even when the toner is subjected to stress such as pressure and heat by the transfer means for transferring the developer from the storage container to the developing container. An object of the present invention is to provide an image forming method and an image forming apparatus capable of suppressing occurrence of “

As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, as a mechanism for forming a toner agglomerate that causes so-called “fireflies” that are abnormal images, a mechanism of rotor and stator in a Mono pump is formed. It is considered that this is because stress due to frictional heat, shearing force, and pressure is applied to the toner present in the narrow portion by the contact. Therefore, even after applying stress due to heat and stress due to pressure, the toners do not adhere to each other due to electrostatic or non-electrostatic adhesion, and do not form aggregates, that is, they have good fluidity (low aggregation properties). ) Is required.
For these reasons, it is important to prevent the toner from being heated and to make it less susceptible to stress due to pressure. Accordingly, the present inventors mixed porous particles having a particle diameter of 1 mm or less together with toner for replenishment (premix toner) in the storage container, and simultaneously developed the porous particles when replenishing the toner for replenishment (premix toner). It has been found that it is effective to supply the container.
Here, when the particle size of the porous particles exceeds 1 mm, there is a concern that the port of the pump is blocked during transfer from the storage container to the developing container, and clogging is likely to occur. The porous particles have excellent endothermic or thermal insulation properties due to their large surface area, and can suppress a decrease in the hardness of the toner and an accompanying increase in adhesion between the toners. Further, if the porous particles used are materials having high flexibility such as airgel, they can act as a buffer material by entering between the toner particles, and stress due to pressure can be reduced.
In addition, by mixing these porous particles with replenishing toner (premix toner) in the storage container, stress due to pressure by an auger or screw in the toner transfer device that transfers the toner to the developing container is avoided. Can do.

On the other hand, when the porous particles are replenished into the developing container together with the supply of replenishing toner (premix toner), the porous particles are not charged and are not used for development, and therefore remain in the developing container. It will be accumulated in. However, the present inventors have also solved the problem as follows.
Conventionally, developing means for replenishing premixed toner consisting of carrier and toner and discharging excess developer, that is, toner consumed by developing operation in order to eliminate the need to replace the developer. During normal operation of additional replenishment, a small amount of developer consisting of a mixture with toner containing carrier is replenished into the developer container, and by replacing the deteriorated developer with reduced charging performance, a small amount of developer is discharged from the developer container. A developing means has been proposed that can suppress a decrease in performance. Such a technique is known as a “trickle development system”. In this trickle development method, the developer in the developer container increases in volume because new toner and new carrier are replenished in the developer container, but the excess carrier is removed from the developer provided on the wall of the developer container. It overflows from the outlet, is discharged, and is collected in the developer collection container.
By utilizing this mechanism, the porous particles supplied from the storage container can be collected together with the deteriorated developer in the developer collecting container, and the porous particles can be prevented from continuing to stay in the developing container.
Here, if the ratio of the porous particles mixed in the storage container exceeds 15% by volume with respect to the toner, the supply of the porous particles becomes excessive at the time of toner supply, and conversely, the toner supply becomes insufficient. There is a concern that the toner concentration in the developing container becomes abnormal, and image problems such as toner scattering and background contamination may occur. As a result, the cohesiveness of the toner after applying pressure and thermal stress is suppressed within a certain level, that is, by maintaining a constant fluidity, adhesion between the toners is suppressed and generation of slow aggregates is suppressed. It was found that the occurrence of “fireflies”, which are abnormal images associated therewith, can be suppressed.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> an electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier;
A developing step of developing the electrostatic latent image using a toner contained in a developing container to form a visible image;
A transfer step of transferring the visible image to a recording medium;
A fixing step of fixing the transferred image transferred to the recording medium;
A toner transfer step of supplying replenishment toner stored in a storage container from the storage container to the developing container in accordance with the amount of toner consumed during image formation;
An image forming method including a surplus developer discharging step of discharging surplus developer remaining in the developing container due to replenishment of the replenishing toner in the toner transfer step to the outside of the developing container,
As the replenishment toner, a premix toner in which a toner and a carrier are mixed at a certain ratio is used, and contains 10% by volume to 15% by volume of porous particles having a particle diameter of 1 mm or less with respect to the toner in the premix toner. This is an image forming method.
<2> The image forming method according to <1>, wherein an airgel is used as the porous particles.
<3> A prepolymer containing a binder resin and a modified polyester resin in an organic solvent, a compound that extends or crosslinks with the prepolymer, a colorant, a release agent, and at least interlayer ions in the layered inorganic mineral It was obtained by dissolving or dispersing a modified layered inorganic mineral partially modified with organic ions and having a Casson yield value at 25 ° C. of 1 Pa to 100 Pa obtained by crosslinking or extending the dispersion in an aqueous medium. The image forming method according to any one of <1> to <2>, wherein a toner obtained by removing the solvent from the dispersion is used.
<4> The image forming method according to <3>, wherein the content of the modified layered inorganic mineral is 0.05% by mass to 10% by mass with respect to the solid content in the solution or dispersion.
<5> The image forming method according to any one of <1> to <4>, wherein a toner having an average circularity of 0.94 to 0.99 is used.
<6> Toner having a volume average particle diameter of 3 μm to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of 1.00 to 1.30 The image forming method according to any one of <1> to <5>, wherein
<7> The image forming method according to any one of <1> to <6>, wherein a toner having a ratio of particles having a particle size of 2 μm or less is 1% by number to 10% by number.
<8> From the above <1> to <7, wherein a toner obtained by externally adding fine particles having an average primary particle diameter of 50 nm to 500 nm and a bulk density of 0.3 g / cm ³ or more is used on the surface of the toner base particles. > The image forming method according to any one of the above.
<9> an electrostatic latent image carrier, and electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier;
A developing unit having a stirring and conveying mechanism that develops the electrostatic latent image using a toner contained in a developing container to form a visible image;
Transfer means for transferring the visible image to a recording medium;
Fixing means for fixing the transferred image transferred to the recording medium;
Toner transfer means for replenishing the replenishment toner stored in the storage container from the storage container to the developing container according to the amount of toner consumed in the image formation;
An image forming apparatus having surplus developer discharging means for discharging surplus developer that has become surplus in the developing container due to replenishment of replenishing toner in the toner transfer step;
The replenishment toner is a premix toner in which a toner and a carrier are mixed at a constant ratio, and contains 10% by volume to 15% by volume of porous particles having a particle diameter of 1 mm or less with respect to the toner in the premix toner. An image forming apparatus characterized by the above.
<10> The image forming apparatus according to <9>, wherein the toner transfer unit is a screw pump.
<11> From the above <9>, comprising a process cartridge having an electrostatic latent image carrier and at least one means selected from a developing means, a charging means, a transfer means, and a cleaning means, which is detachable from the image forming apparatus main body. The image forming apparatus according to any one of <10>.

  According to the present invention, various problems in the prior art can be solved, and even if the toner is subjected to stress such as pressure and heat by a transfer means (for example, a Mono pump) for transferring the developer from the storage container to the developer container, the toner is relaxed. It is possible to provide an image forming method and an image forming apparatus capable of suppressing the occurrence of “fireflies” that are abnormal images without forming aggregates.

(Image forming method and image forming apparatus)
The image forming method of the present invention includes an electrostatic latent image forming step, a developing step, a transfer step, a fixing step, a toner transfer step, and an excess developer discharging step, and further steps as necessary. Comprising.
The image forming apparatus of the present invention includes an electrostatic latent image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, a fixing unit, a toner transfer unit, and an excess developer discharging unit. In addition, other means are provided as necessary.

  The image forming method according to the present invention can be preferably carried out by the image forming apparatus of the present invention, the electrostatic latent image forming step can be performed by the electrostatic latent image forming means, and the developing step is the developing The transfer step can be performed by the transfer unit, the fixing step can be performed by the fixing unit, the toner transfer step can be performed by the toner transfer unit, and the surplus The developer discharging step can be performed by the excess developer discharging means, and the other steps can be performed by the other means.

-Electrostatic latent image forming step and electrostatic latent image forming means-
The electrostatic latent image forming step is a step of forming an electrostatic latent image on the electrostatic latent image carrier.
The electrostatic latent image carrier (sometimes referred to as “electrophotographic photosensitive member” or “photosensitive member”) is not particularly limited in terms of material, shape, structure, size, etc. Although it can be selected as appropriate, the shape thereof is preferably a drum shape, and examples of the material include inorganic photoreceptors such as amorphous silicon and selenium, and organic photoreceptors such as polysilane and phthalopolymethine. . Among these, amorphous silicon or the like is preferable in terms of long life.

  As the amorphous silicon photoreceptor, for example, a support is heated to 50 ° C. to 400 ° C., and a vacuum deposition method, a sputtering method, an ion plating method, a thermal CVD method, a photo CVD method, a plasma CVD method is applied on the support. A photoconductor having a photoconductive layer made of a-Si (hereinafter sometimes referred to as “a-Si-based photoconductor”) can be used by a film forming method such as the above. Among these, a plasma CVD method, that is, a method in which a source gas is decomposed by direct current, high frequency or microwave glow discharge to form an a-Si deposited film on a support is preferable.

The formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the electrostatic latent image carrier and then performing imagewise exposure, and is performed by the electrostatic latent image forming unit. Can do.
The electrostatic latent image forming unit includes, for example, at least a charger that uniformly charges the surface of the electrostatic latent image carrier and an exposure device that exposes the surface of the latent image carrier imagewise.

The charging can be performed, for example, by applying a voltage to the surface of the electrostatic latent image carrier using the charger.
The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charging device including a conductive or semiconductive roller, brush, film, rubber blade, etc. And non-contact chargers utilizing corona discharge such as corotrons and corotrons.

The shape of the charging member may take any form such as a magnetic brush or a fur brush in addition to a roller, and can be selected according to the specifications and form of the image forming apparatus. When using a magnetic brush, the magnetic brush is composed of various ferrite particles such as Zn-Cu ferrite as a charging member, a non-magnetic conductive sleeve for supporting it, and a magnet roll included therein. The Or, when using a brush, for example, as a material of the fur brush, a fur treated with carbon, copper sulfide, metal or metal oxide is used, and this is wound or attached to a metal or other conductive core. To make a charger.
The charger is not limited to the contact charger as described above. However, since an image forming apparatus in which ozone generated from the charger is reduced is obtained, a contact charger is used. preferable.

The exposure can be performed, for example, by exposing the surface of the latent electrostatic image bearing member imagewise using the exposure device.
The exposure device is not particularly limited as long as it can expose the surface of the electrostatic latent image carrier charged by the charger so as to form an image to be formed, and is appropriately selected according to the purpose. For example, various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system can be used.
In the present invention, a back light system in which imagewise exposure is performed from the back side of the electrostatic latent image carrier may be employed.

-Development means and development process-
The developing step is a step of developing the electrostatic latent image with toner stored in a developing container to form a visible image, and can be performed using a developing unit.
The developing means is not particularly limited and may be appropriately selected from known ones. The developing means has a developing container that can store toner and can apply toner to a latent electrostatic image in a contact or non-contact manner. The image forming apparatus includes a developing roller that supplies toner to the electrostatic latent image and performs development, a supply roller that supplies toner to the developing roller, and a stirring and conveying mechanism, and further includes other members as necessary.
Examples of the agitation transport mechanism include a screw and a paddle.

〔toner〕
The toner is not particularly limited and may be appropriately selected depending on the intended purpose. However, a prepolymer composed of a binder resin and a modified polyester resin in an organic solvent, a compound that extends or crosslinks with the prepolymer, Dissolve or disperse a colorant, a release agent, or a modified layered inorganic mineral (hereinafter sometimes referred to as “modified layered inorganic mineral”) in which at least a part of interlayer ions in the layered inorganic mineral is modified with organic ions. It is preferable that the toner is obtained by emulsifying or dispersing a dispersion in an aqueous medium to cause crosslinking or elongation reaction and removing the solvent from the obtained dispersion.

A solution or dispersion in which a prepolymer comprising a binder resin or a modified polyester resin, a compound that extends or crosslinks with the prepolymer, a colorant, a release agent, or a modified layered inorganic mineral is dissolved or dispersed in at least the organic solvent. The Casson yield value at 25 ° C. is preferably 1 Pa to 100 Pa, and more preferably 5 Pa to 50 Pa.
When the Casson yield value is less than 1 Pa, it may be difficult to obtain a target toner shape, and when it exceeds 100 Pa, the toner productivity may be deteriorated.
Here, the Casson yield value is obtained by measuring the viscosity of the oil phase alone when emulsified in an aqueous medium, and can be measured using, for example, a high shear viscometer.

  Specifically, the toner includes at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester resin, a compound that extends or crosslinks with the prepolymer, a colorant, a release agent, and a modified layered inorganic mineral in an organic solvent. The toner material dispersed therein is obtained by crosslinking or elongation reaction in an aqueous solvent.

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

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

The ratio between the polyhydric alcohol (PO) and the polyhydric carboxylic acid (PC) is 2/1 to 1/1 as an equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is preferable, 1.5 / 1 to 1/1 is more preferable, and 1.3 / 1 to 1.02 / 1 is still more preferable.
The polycondensation reaction of polyhydric alcohol (PO) and polycarboxylic acid (PC) is heated to 150 ° C to 280 ° C in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and reduced in pressure if necessary. The produced water is distilled off to obtain a polyester resin having a hydroxyl group.
The hydroxyl value of the polyester resin is preferably 5 mgKOH / g or more. The acid value of the polyester resin is preferably 1 mgKOH / g to 30 mgKOH / g, more preferably 5 mgKOH / g to 20 mgKOH / g. By giving an acid value, the toner tends to be negatively charged, and further, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixing property is improved. However, when the acid value exceeds 30 mgKOH / g, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation.
The polyester resin has a mass average molecular weight of preferably 10,000 to 400,000, more preferably 20,000 to 200,000. When the mass average molecular weight is less than 10,000, the offset resistance may be deteriorated, and when it exceeds 400,000, the low-temperature fixability may be deteriorated.

  As the prepolymer comprising the modified polyester resin, a polyester prepolymer having a functional group containing a nitrogen atom is preferable, and as the polyester prepolymer having a functional group containing a nitrogen atom, the terminal of the polyester obtained by the above polycondensation reaction is used. A polyester prepolymer (A) having an isocyanate group obtained by reacting a carboxyl group, a hydroxyl group or the like with a polyvalent isocyanate compound (PIC) is preferable. In this case, examples of the compound that extends or crosslinks with the prepolymer include amines. By reacting the polyester prepolymer (A) having an isocyanate group with amines, the molecular chain is cross-linked and / or elongated to obtain a urea-modified polyester.

Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; Those blocked with caprolactam and the like; and combinations of two or more of these.
The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.
The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is preferably 0.5% by mass to 40% by mass, more preferably 1% by mass to 30% by mass. The mass% to 20 mass% is more preferable. When the content is less than 0.5% by mass, the hot offset resistance is deteriorated, which may be disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability, and when it exceeds 40% by mass, Low temperature fixability may deteriorate.

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 on average, more preferably 1.8 to 2 on average. .5. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.
Next, as the amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acid block of B1 to B5 (B6).
Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.). Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the compound (B6) obtained by blocking the amino group of B1 to B5 include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.
The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). 1/2 to 2/1 is preferable, 1.5 / 1 to 1 / 1.5 is more preferable, and 1.2 / 1 to 1 / 1.2 is still more preferable. When the [NCO] / [NHx] exceeds 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance may be deteriorated.

The urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio between the urea bond content and the urethane bond content is preferably 100/0 to 10/90, more preferably 80/20 to 20/80, and still more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance may be deteriorated.
The urea-modified polyester is produced by a one-shot method or the like. Water produced by heating polyhydric alcohol (PO) and polyhydric carboxylic acid (PC) to 150 ° C. to 280 ° C. in the presence of a known esterification catalyst such as tetrabutoxy titanate and dibutyltin oxide, and if necessary, reducing the pressure. Is distilled off to obtain a polyester having a hydroxyl group. Next, at 40 ° C. to 140 ° C., polyisocyanate (PIC) is reacted with this to obtain a polyester prepolymer (A) having an isocyanate group. Further, this (A) is reacted with amines (B) at 0 ° C. to 140 ° C. to obtain a urea-modified polyester.
When reacting (PIC) and when reacting (A) and (B), a solvent may be used if necessary. Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers And those inert to isocyanates (PIC) such as tetrahydrofuran (such as tetrahydrofuran).
In addition, in the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B), a reaction terminator may be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those blocked (ketimine compounds).
The mass average molecular weight of the urea-modified polyester is preferably 10,000 or more, more preferably 20,000 to 10,000,000, and still more preferably 30,000 to 1,000,000. When the mass average molecular weight is less than 10,000, the hot offset resistance may be deteriorated. The number average molecular weight of the urea-modified polyester or the like is not particularly limited when the above-mentioned unmodified polyester is used, and may be a number average molecular weight that can be easily obtained to obtain the mass average molecular weight. When the urea-modified polyester is used alone, the number average molecular weight is preferably 2000 to 15000, more preferably 2000 to 10000, and further preferably 2000 to 8000. When the number average molecular weight exceeds 20000, low temperature fixability and gloss when used in a full color apparatus may be deteriorated.

By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the gloss when used in the full-color image forming apparatus 100 are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond.
The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition.
The mass ratio of unmodified polyester and urea-modified polyester is preferably 20/80 to 95/5, more preferably 70/30 to 95/5, still more preferably 75/25 to 95/5, and 80/20. ~ 93/7 is particularly preferred. When the mass ratio of the urea-modified polyester is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.
The glass transition point (Tg) of the binder resin containing unmodified polyester and urea-modified polyester is preferably 45 ° C to 65 ° C, more preferably 45 ° C to 60 ° C. When the glass transition temperature is less than 45 ° C., the heat resistance of the toner may deteriorate, and when it exceeds 65 ° C., the low-temperature fixability may be insufficient.
In addition, since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the heat-resistant storage stability tends to be good even when the glass transition point is low as compared with known polyester-based toners.

-Colorant-
The colorant is not particularly limited, and all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow , Yellow iron oxide, ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Tan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Faisa Red, Lachlor Ortho Nitroaniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carnmin BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Tolujing 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 , Pyrazolone red, polyazo red, chrome vermilion, benzidine orange, perinone orange, oil orange, cobalt blue, cerulean blue, alkali blue rake, peacock blue rake, Victoria blue rake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, Indanthrene blue (RS, BC), indigo, ultramarine, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt violet, 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 Examples include green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, litbon, or a mixture thereof.
The content of the colorant is preferably 1% by mass to 15% by mass and more preferably 3% by mass to 10% by mass with respect to the toner.

  The colorant can also be used as a master batch combined with a resin. As the binder resin to be kneaded together with the production of the master batch, for example, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyl toluene, or a substituted product thereof, or a copolymer of these 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 paraffin, paraffin wax and the like can be mentioned. These may be used individually by 1 type and may use 2 or more types together.

-Charge control agent-
The charge control agent is not particularly limited and known ones can be used. For example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, 4 Examples include quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus simple substances or compounds, tungsten simple substances or compounds, fluorine-based activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenol-condensate E-89 (above, manufactured by Orient Chemical Co., Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, manufactured by Hodogaya Chemical Co., Ltd.), quaternary ammonium salt Copy charge PSY VP2038, triphenylmethane derivative copy blue PR, quaternary ammonium salt copy charge NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, boron complex LR-147 (Japan) Carlit Co., Ltd.), copper phthalocyanine, perylene, ki Kuridon, azo pigments, sulfonate group, carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts. These may be used individually by 1 type and may use 2 or more types together. Among these, a substance that controls the negative polarity of the toner is particularly preferable.
The content of the charge control agent is determined by the toner production method including the type of the binder resin, the presence or absence of additives used as necessary, and the dispersion method, and is not uniquely limited. However, 0.1 mass part-10 mass parts are preferable with respect to 100 mass parts of binder resin, and 0.2 mass part-5 mass parts are more preferable. When the content exceeds 10 parts by mass, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attractive force with the developing roller is increased, the flowability of the developer is reduced, The image density may be lowered.

-Release agent-
As the release agent, a low melting point wax having a melting point of 50 ° C. to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface. Effective against high temperature offset without applying a release agent such as oil to the fixing roller. Examples of such a wax component include the following. As waxes and waxes, plant waxes such as carnauba wax, cotton wax, wood wax, rice wax; animal waxes such as beeswax and lanolin; mineral waxes such as ozokerite and cercin; paraffin, microcrystalline, petrolatum, etc. Oil wax, and the like. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax; synthetic waxes such as esters, ketones, ethers and the like can be mentioned. Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorinated hydrocarbon, and low molecular weight crystalline polymer resin, poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain, such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be used. .
The charge control agent and the release agent 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.

-Modified layered inorganic mineral-
The modified layered inorganic mineral is a layered inorganic mineral obtained by converting at least part of ions between layers in the layered inorganic mineral with organic ions, for example, at least part of metal cations between layers converted with quaternary ammonium ions, etc. Examples thereof include organically modified montmorillonite and organically modified smectite.
The content of the modified layered inorganic mineral is preferably 0.05% by mass to 10% by mass and more preferably 0.1% by mass to 5% by mass with respect to the solid content in the dissolved or dispersed liquid. If the content is less than 0.05% by mass, the target Casson yield value may not be obtained, and if it exceeds 10% by mass, the fixing performance may be deteriorated.

<Toner production method>
The method for producing the toner is not particularly limited and can be appropriately selected according to the purpose from conventionally known toner production methods. For example, a kneading / pulverizing method, a polymerization method, a dissolution suspension method, The spray granulation method etc. are mentioned.

In the kneading and pulverizing method, for example, a toner material containing at least a binder resin, a pigment, and a pigment dispersant is melt-kneaded, and the obtained kneaded material is pulverized and classified. It is a manufacturing method.
In the melt kneading, the toner materials are mixed, and the mixture is charged into a melt kneader and melt kneaded.
In this case, the toner material is melt-kneaded after dry mixing. It is preferred that copper phthalocyanine and aluminum phthalocyanine are first mixed in powder form.
As the melt kneader, for example, a uniaxial or biaxial continuous kneader or a batch kneader using a roll mill can be used. For example, a KTK type twin screw extruder manufactured by Kobe Steel, a TEM type extruder manufactured by Toshiba Machine Co., Ltd., a twin screw extruder manufactured by Casey Kay Co., Ltd., a PCM type twin screw extruder manufactured by Ikegai Co., Ltd. Used. This melt-kneading is preferably performed under appropriate conditions so as not to cause the molecular chains of the binder resin to be broken. Specifically, the melt-kneading temperature is determined with reference to the softening point of the binder resin. If the temperature is higher than the softening point, cutting is severe, and if the temperature is too low, dispersion may not proceed.

  In the pulverization, the kneaded product obtained by the kneading is pulverized. In this pulverization, it is preferable that the kneaded material is first coarsely pulverized and then finely pulverized. At this time, a method of pulverizing by colliding with a collision plate in a jet stream, pulverizing particles by colliding with each other in a jet stream, or pulverizing with a narrow gap between a mechanically rotating rotor and a stator is preferably used.

In the classification, the pulverized product obtained by the pulverization is classified and adjusted to particles having a predetermined particle diameter. The classification can be performed, for example, by removing the fine particle portion with a cyclone, a decanter, a centrifuge, or the like.
After the pulverization and classification are completed, the pulverized product is classified into an air stream by centrifugal force or the like, and toner base particles having a predetermined particle diameter can be produced.

  Next, the external additive is externally added to the toner base particles. By mixing and stirring the toner base particles and the external additive using a mixer, the surface of the toner base particles is coated while being crushed. At this time, it is important from the viewpoint of durability that the external additives such as inorganic fine particles and resin fine particles are uniformly and firmly attached to the toner base particles.

  As a method for producing a toner by the polymerization method, a binder resin, a prepolymer containing a modified polyester resin, a compound that undergoes elongation or cross-linking reaction with the prepolymer, a colorant, a release agent, and a modification in an organic solvent. A method in which the solvent is removed from the dispersion obtained by dissolving or dispersing the layered inorganic mineral in the aqueous medium and crosslinking or stretching the dispersion in an aqueous medium is preferred.

(1) Unmodified polyester, polyester prepolymer having an isocyanate group, compounds that extend or crosslink with the prepolymer (amines), colorants, release agents, and at least part of interlayer ions in layered inorganic minerals are organic ions A modified inorganic mineral is dispersed in an organic solvent to prepare a toner material liquid.
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. These may be used individually by 1 type and may use 2 or more types together. Among these, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are particularly preferable.
300 mass parts or less are preferable with respect to 100 mass parts of polyester prepolymers, and, as for the usage-amount of the said organic solvent, 100 mass parts or less are more preferable, and 25 mass parts-70 mass parts are still more preferable.

(2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium may be water alone, or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). May be included.
The amount of the aqueous medium used with respect to 100 parts by mass of the toner material liquid is preferably 50 parts by mass to 2000 parts by mass, and more preferably 100 parts by mass to 1000 parts by mass. If the amount used is less than 50 parts by mass, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by mass, it is not economical.
Further, in order to improve the dispersion in the aqueous medium, it is preferable to add a dispersant such as a surfactant and resin fine particles as appropriate.
Examples of the surfactant include anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, and phosphate esters; amine salt types such as alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazolines; Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride; fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives; amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine, N-alkyl-N, N-dimethylammonium betaine, etc. That.
Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms or metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acid or metal salt thereof, perfluoroalkylcarboxylic acid (C7 to C13) or metal salt thereof, perfluoroalkyl (C4 to C12) sulfonic acid or metal salt thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- (2-hydroxyethyl) par Fluorooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Can be mentioned.
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 & Chemicals, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products Co., Ltd.), Footent F-100, F150 (manufactured by Neos), and the like. It is done.
In addition, as the cationic surfactant, aliphatic quaternary ammonium salts such as aliphatic primary, secondary or tertiary amine acids having a fluoroalkyl group, and perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salts. , Benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (manufactured by Asahi Glass Co., Ltd.), Florard FC-135 (manufactured by Sumitomo 3M Co., Ltd.), Unidyne DS-202 (Daikin) Industrial Co., Ltd.), MegaFuck F-150, F-824 (Dainippon Ink Chemical Co., Ltd.), Xtop EF-132 (Tochem Products Co., Ltd.), Footent F-300 (Neos Co., Ltd.), Etc.

The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10% to 90%. For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao Corporation), SGP (manufactured by Soken Co., Ltd.) , Technopolymer SB (manufactured by Sekisui Plastics Co., Ltd.), SGP-3G (manufactured by Soken Co., Ltd.), Micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.) and the like.
In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

  As a dispersant that can be used in combination with the resin fine particles and the inorganic compound dispersant, the dispersed droplets may be stabilized by a polymeric protective colloid. For example, acids such as acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride; (meth) acrylic monomers containing hydroxyl groups (For example, acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxypropyl , Acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate , N-methylol acrylamide, N-methylol methacrylamide, etc.); vinyl alcohol or ethers with vinyl alcohol (for example, vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc.); esters of compounds containing vinyl alcohol and a carboxyl group (For example, vinyl acetate, vinyl propionate, vinyl butyrate, etc.); acid chlorides such as acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acrylic acid chloride, methacrylic acid chloride; vinyl pyridine, vinyl pyrrolidone, vinyl imidazole , Nitrogen-containing compounds such as ethyleneimine; or homopolymers or copolymers such as those having a heterocyclic ring thereof; polyoxyethylene, polyoxypropylene, polyoxy Tylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonyl phenyl ester, etc. Polyoxyethylene-based; celluloses such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and the like can be used.

  There is no restriction | limiting in particular as a method of dispersion | distribution, According to the objective, it can select suitably, For example, well-known facilities, such as a low-speed shear type, a high-speed shear type, a friction type, a high-pressure jet type, and an ultrasonic wave, are applicable. Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 μm to 20 μm. When a high-speed shearing disperser is used, the number of rotations is not particularly limited and can be appropriately selected according to the purpose, preferably 1,000 rpm to 30,000 rpm, more preferably 5,000 rpm to 20,000 rpm. . There is no restriction | limiting in particular about dispersion time, According to the objective, it can select suitably, In the case of a batch system, 0.1 minute-5 minutes are preferable. The temperature during dispersion is preferably 0 ° C to 150 ° C (under pressure), more preferably 40 ° C to 98 ° C.

(3) Simultaneously with the production of the emulsion, the reaction with the polyester prepolymer (A) having an isocyanate group is carried out.
This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity of the isocyanate group structure of the polyester prepolymer (A) with the amines (B), but is usually 10 minutes to 40 hours, preferably 2 hours to 24 hours. The reaction temperature is preferably 0 ° C to 150 ° C, more preferably 40 ° C to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

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

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

-Fine particles-
The toner used in the present invention was obtained by externally adding fine particles having an average primary particle diameter of 50 nm to 500 nm and a bulk density of 0.3 g / cm ³ or more (hereinafter simply referred to as fine particles) to the surface of the toner base particles. A toner is preferable.
By using fine particles having an average primary particle size of 50 nm to 500 nm and a bulk density of 0.3 g / cm ³ or more as an external additive, a small particle size toner having good cleaning properties and particularly achieving high image quality. When used, improvement in developability and transferability is improved.
Although silica is often used in the conventional flow improvers, for example, the average primary particle size of the silica is preferably from 5 nm to 30 nm, a volume density of 0.1g ^/ cm ³ ~0.2g ^/ cm 3 is there.

In the present invention, the presence of fine particles having appropriate characteristics on the surface of the toner forms an appropriate gap between the toner particles and the target. Further, the fine particles have a very small contact area with the toner particles, the photoconductor, and the charge imparting member and are evenly contacted with each other. Furthermore, since it plays the role of a roller, it is difficult to be embedded in toner particles even when the cleaning blade and the photoconductor are cleaned under high stress (high load, high speed, etc.) without wearing or damaging the photoconductor. Or, even if it is buried a little, it can be detached and restored, so that stable characteristics can be obtained over a long period of time. Further, the toner is moderately detached from the surface of the toner and accumulated at the tip of the cleaning blade, and the so-called dam effect has an effect of preventing the phenomenon that the toner passes from the blade. Since these characteristics have an effect of reducing the share received by the toner particles, the filming effect of the toner itself due to the low rheological component contained in the toner is exhibited for high-speed fixing (low energy fixing). In addition, when the fine particles having an average primary particle size in the range of 50 μm to 500 μm are used, the excellent cleaning performance can be fully utilized, and since the particle size is extremely small, the powder fluidity of the toner Is not reduced. Further, although the details are not clear, even if the surface-treated fine particles are externally added to the toner or the carrier is contaminated, the degree of developer deterioration is small.
The average primary particle size of the fine particles is preferably 50 nm to 500 nm, and more preferably 100 nm to 400 nm. If the average primary particle size is less than 50 nm, the fine particles may be buried in the concave and convex portions of the irregularities on the toner surface, reducing the role of the rollers. On the other hand, when the average primary particle size is larger than 500 nm, when the fine particles are positioned between the blade and the surface of the photoreceptor, the toner particles have an order of the same level as the contact area of the toner itself, and pass the toner particles to be cleaned. That is, it becomes easy to generate a cleaning defect.

When the volume density of the fine particles is less than 0.3 g / cm ³ , although there is a contribution to the improvement of fluidity, the scattering property and adhesion of the toner and fine particles are increased, A function such as a so-called dam effect that accumulates in the cleaning unit and prevents toner cleaning failure is reduced.
The bulk density of the fine particles was measured by the following method. Using a 100 ml graduated cylinder, fine particles were gradually added to make 100 ml.
At that time, no vibration was applied. The bulk density was measured by the difference in mass before and after putting the fine particles of the graduated cylinder.
Bulk density (g / cm ³ ) = fine particle amount (g / 100 ml) ÷ 100

Examples of the fine particles include inorganic compound particles and organic compound particles.
Examples of the inorganic compound particles include SiO ₂ , TiO ₂ , Al ₂ O ₃ , MgO, CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , BaO, CaO, K ₂ O, Na ₂ O, and ZrO. ₂ , CaO.SiO ₂ , K ₂ O (TiO ₂ ) _n , Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO ₄ , SrTiO ₃ , and the like. Among _{these, SiO 2, TiO 2, Al} 2 O 3 is particularly preferred. These inorganic compounds may be hydrophobized with various coupling agents, hexamethyldisilazane, dimethyldichlorosilane, octyltrimethoxysilane, and the like.
The fine particles of the organic compound may be thermoplastic resins or thermosetting resins, for example, vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicon resins, phenol resins, melamine resins, ureas. Resins, aniline resins, ionomer resins, polycarbonate resins and the like can be mentioned. As the resin fine particles, two or more of the above resins may be used in combination. Among these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are particularly preferable because an aqueous dispersion of fine spherical resin particles can be easily obtained.
Examples of the vinyl resin include polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene- (meth) acrylic acid ester copolymer, styrene-butadiene copolymer, (meth) acrylic acid-acrylic acid. Examples thereof include ester copolymers, styrene-acrylonitrile copolymers, styrene-maleic anhydride copolymers, styrene- (meth) acrylic acid copolymers, and the like.
The fine particles can be externally added and adhered to the toner surface by a method in which the toner base particles and the fine particles are mechanically mixed and adhered using various known mixing devices, or the toner base particles in the liquid phase. And a method in which the fine particles are uniformly dispersed with a surfactant or the like, and are dried after the adhesion treatment.

The toner used in the present invention has a volume average particle diameter of 3 μm to 8 μm, and the ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is 1.00 to 1. 30 is preferable.
The volume average particle diameter (Dv) is more preferably 3.0 μm to 7.0 μm. In general, it is said that the smaller the particle size of the toner, the more advantageous it is to obtain a high-resolution and high-quality image, but it is disadvantageous for transferability and cleaning properties. is there. When the volume average particle diameter is smaller than the above range, in the case of a two-component developer, the toner is fused to the surface of the carrier during a long period of stirring in the developing device, and the charging ability of the carrier is reduced. When it is used, toner filming on the developing roller and toner fusion to a member such as a blade for thinning the toner are likely to occur.
When the ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of the toner is in the range of 1.00 to 1.30, a high-resolution and high-quality toner is obtained. Is possible. Furthermore, in the case of a two-component developer, even if a long-term balance of the toner is performed, fluctuations in the particle size of the toner in the developer are reduced, and good and stable developability even with long-term stirring in the developing device. Is possible. If Dv / Dn exceeds 1.30, the particle size variation of individual toner particles is large, and the toner behavior varies during development and the like, and the reproducibility of minute dots is impaired. Therefore, a high-quality image cannot be obtained. More preferably, Dv / Dn is in the range of 1.00 to 1.20, and a better image can be obtained.

In order to reproduce minute dots of 600 dpi or more, the toner preferably has a volume average particle size of 3 μm to 8 μm. The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is preferably in the range of 1.00 to 1.30. The closer the (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.
Here, the particle size distribution of the toner can be measured by a Coulter counter method. Examples of the measuring device for the particle size distribution of the toner particles include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). The measurement method is described below.
First, 0.1 to 5 ml of a surfactant (preferably an alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of an electrolytic aqueous solution. Here, the electrolytic solution is prepared by preparing a 1% by mass NaCl aqueous solution using first grade sodium chloride, and for example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for 1 to 3 minutes with an ultrasonic disperser, and the volume and number of toner particles or toner are measured with the measurement device using a 100 μm aperture as the aperture. Calculate distribution and number distribution. From the obtained distribution, the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the toner can be obtained.
As a channel, it is 2.00 micrometers or more and less than 2.52 micrometers; 2.52 micrometers or more and less than 3.17 micrometers; 3.17 micrometers or more and less than 4.00 micrometers; 4.00 micrometers or more and less than 5.04 micrometers; 5.04 micrometers or more and less than 6.35 micrometers; .35 μm or more and less than 8.00 μm; 8.00 μm or more and less than 10.08 μm; 10.08 μm or more and less than 12.70 μm; 12.70 μm or more and less than 16.00 μm; 16.00 μm or more and less than 20.20 μm; Less than 40 μm; 25.40 μm or more and less than 32.00 μm; 3 channels of 32.00 μm or more and less than 40.30 μm are used, and particles having a particle size of 2.00 μm or more and less than 40.30 μm are targeted.

In the toner used in the present invention, the ratio of particles having a particle diameter of 2 μm or less is preferably 1% to 10%.
The phenomenon of defects due to the above-mentioned particle size is greatly related to the content of fine powder, and when the number of particles having a particle size of 2 μm or less exceeds 10% by number, it becomes an obstacle when the adhesion to the carrier or the charging stability at a high level is achieved. . Conversely, when the toner particle size is larger than the above range, it becomes difficult to obtain a high-resolution and high-quality image, and the toner particle size when the balance of the toner in the developer is performed. In many cases, fluctuations of It was also clarified that the same applies when the volume average particle diameter / number average particle diameter is larger than 1.30.

The average circularity of the toner is preferably 0.94 to 0.99.
Here, the particle ratio and circularity of the particle size of 2 μm or less can be measured by a flow type particle image analyzer FPIA-2000 (manufactured by Sysmex Corporation). As a specific measurement method, 0.1 ml to 0.5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 ml to 150 ml of water from which impure solids have been removed in advance. Add about 0.1-0.5g of sample. The suspension in which the sample is dispersed is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes. can get.

The toner used in the present invention preferably has a substantially spherical shape, and can be represented by the following shape rule.
It is a figure which shows typically the shape of the toner of this invention. In FIG. 3, when a substantially spherical toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), the toner of the present invention has a major axis and a minor axis. Ratio (r2 / r1) (see FIG. 3B) is 0.5 to 1.0, and the ratio of thickness to minor axis (r3 / r2) (see FIG. 3C) is 0.7 to 1.0. It is preferable to be in the range of 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, when the ratio of the thickness to the short axis (r3 / r2) is less than 0.7, it becomes 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, a rotating body having the long axis as the rotation axis is obtained, and the fluidity of the toner can be improved.
The r1, r2, and r3 can be measured by the following method, for example. That is, the toner is uniformly dispersed and adhered on a smooth measurement surface, and 100 particles of the toner are magnified 500 times by a color laser microscope “VK-8500” (manufactured by Keyence Corporation). The major axis r1 (μm), the minor axis r2 (μm), and the thickness r3 (μm) of the particles can be measured and obtained from their arithmetic average values.

  The developer used in the present invention contains the toner, and may further contain other components as appropriate such as a carrier.

Although the said carrier can be suitably selected according to the objective, what has a core material and the resin layer which coat | covers a core material is preferable.
The material of the core material can be appropriately selected from known materials, and examples thereof include manganese-strontium-based materials and manganese-magnesium-based materials of 50 emu / g to 90 emu / g. In order to ensure the image density, it is preferable to use a highly magnetized material such as iron powder of 100 emu / g or more and magnetite of 75 to 120 emu / g. In addition, it is preferable to use a low-magnetization material such as 30-80 emu / g of copper-zinc system because it can reduce the impact of the developer in a spiked state on the photoconductor and is advantageous for high image quality. . These may be used alone or in combination of two or more.
The volume average particle diameter of the core material is preferably 10 μm to 150 μm, and more preferably 40 μm to 100 μm. When the volume average particle diameter is less than 10 μm, fine powder increases in the carrier, magnetization per particle may decrease and carrier scattering may occur, and when it exceeds 150 μm, the specific surface area decreases, Toner scattering may occur, and in the case of full color with many solid portions, reproduction of the solid portions may be deteriorated.

The material for the resin layer is not particularly limited and may be appropriately selected from known resins according to the purpose. For example, amino resins, polyvinyl resins, polystyrene resins, polyhalogenated olefins, polyester resins Resin, polycarbonate resin, polyethylene, polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, polyhexafluoropropylene, copolymer of vinylidene fluoride and acrylic monomer, copolymer of vinylidene fluoride and vinyl fluoride, tetra Examples thereof include fluoroterpolymers such as copolymers of fluoroethylene, vinylidene fluoride, and monomers having no fluoro group, silicone resins, and the like. These may be used individually by 1 type and may use 2 or more types together.
Specific examples of the amino resin include urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Examples of the polyvinyl resin include acrylic resin, polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, and polyvinyl butyral. Examples of the polystyrene resin include polystyrene and styrene-acrylic copolymer. Examples of the polyhalogenated olefin include polyvinyl chloride. Examples of the polyester resin include polyethylene terephthalate and polybutylene terephthalate.

The resin layer may contain conductive powder or the like as necessary. Specific examples of the conductive powder include metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide. The average particle diameter of the conductive powder is preferably 1 μm or less. When the average particle diameter exceeds 1 μm, it may be difficult to control electric resistance.
The resin layer is formed by preparing a coating solution by dissolving a silicone resin or the like in a solvent, and then coating and drying the coating solution on the surface of the core using a known coating method, followed by baking. Can do. As the coating method, a dip coating method, a spray method, a brush coating method, or the like can be used. There is no restriction | limiting in particular as said solvent, According to the objective, it can select suitably, Toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, butyl cellosolve etc. are mentioned. The baking may be an external heating method or an internal heating method, a method using a fixed electric furnace, a fluid electric furnace, a rotary electric furnace, a burner furnace, a method using a microwave, or the like. Is mentioned.

The content of the resin layer in the carrier is preferably 0.01% by mass to 5.0% by mass. When the content is less than 0.01% by mass, a uniform resin layer may not be formed on the surface of the core material. When the content exceeds 5.0% by mass, the resin layer is thick and the carrier Fusion may occur between them, and the uniformity of the carrier may decrease.
The content of the carrier in the two-component developer is preferably 90% by mass to 98% by mass, and more preferably 93% by mass to 97% by mass.

-Toner transfer process and toner transfer means-
The toner transfer step is a step of supplying the replenishment toner stored in the storage container from the storage container to the developing container according to the amount of toner consumed in the image formation, and is performed by the toner transfer means. .

The replenishment toner is replenished from the storage container into the developing container in accordance with the amount of toner consumed during image formation.
The replenishment toner is a premix toner in which a toner and a carrier are mixed at a constant ratio, and contains 10% by volume to 15% by volume of porous particles having a particle diameter of 1 mm or less with respect to the toner in the premix toner.
The toner in the premix toner is the same as that used in the present invention.
The mixing ratio of the toner and the carrier in the premix toner is not particularly limited and can be appropriately selected depending on the purpose.
Examples of the porous particles include airgel, zeolite, and nanoporous silica.

Examples of the toner transfer means include a Mono pump.
Here, the level values of the stress required for the toner agglomerates to be formed by the MONO pump are as follows. The torque applied to the contact portion between the rotor and the stator in the MONO pump is 0.25 to 1.0 N · M, and further, the heat of about 45 ° C. to 50 ° C. is imparted to the toner present here by the frictional heat applied at that time. Is done. The toner loose agglomerates having a diameter of about 0.5 mm to 2 mm formed by these stresses serve as nuclei and generate “fireflies” which are a large amount of abnormal images.

-Surplus developer discharging process and surplus developer discharging means-
The surplus developer discharging step is a step of discharging surplus developer that has become surplus in the developing container due to replenishment of the replenishing toner in the toner transfer step, and is performed by the surplus developer discharging means. .

-Transfer process and transfer means-
The transfer step is a step of transferring a visible image to a recording medium. The intermediate transfer member is used to primarily transfer the visible image onto the intermediate transfer member, and then the secondary transfer of the visible image onto the recording medium. It is preferable. At this time, the toner used is usually two or more colors, and it is preferable to use a full-color toner. For this reason, it is more preferable to have a primary transfer process in which a visible image is transferred onto an intermediate transfer member to form a composite transfer image, and a secondary transfer process in which the composite transfer image is transferred onto a recording medium.
The transfer can be performed by charging the image carrier using a transfer unit. The transfer means preferably has a primary transfer means for transferring a visible image onto an intermediate transfer member to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium. The intermediate transfer member can be appropriately selected from known transfer members according to the purpose, and a transfer belt or the like can be used.
The transfer means preferably has a transfer device that peels and charges the visible image formed on the image carrier to the recording medium side. There may be one transfer means or a plurality of transfer means. Specific examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device. The recording medium can be appropriately selected from known recording media, and recording paper or the like can be used.

-Fixing process and fixing means-
The fixing step is a step of fixing the visible image transferred to the recording medium using a fixing unit, and may be fixed each time the toner of each color is transferred to the recording medium, or the toner of each color is laminated. You may fix at once in the state. The fixing unit can be appropriately selected according to the purpose, but a known heating and pressing unit can be used. Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt. The heating in the heating and pressurizing means is usually preferably 80 ° C to 200 ° C. A known optical fixing device may be used together with or instead of the fixing unit depending on the purpose.

  The neutralization step is a step of neutralizing by applying a neutralization bias to the image carrier, and can be performed using a neutralization unit. The neutralization means can be appropriately selected from known neutralizers, and a neutralization lamp or the like can be used.

  The cleaning step is a step of removing toner remaining on the image carrier and can be performed using a cleaning unit. The cleaning means can be appropriately selected from known cleaners. For example, a magnetic brush cleaner, electrostatic brush cleaner, magnetic roller cleaner, blade cleaner, brush cleaner, web cleaner, or the like can be used.

  The recycling step is a step of recycling the toner removed in the cleaning step by the developing means, and can be performed using the recycling means. The recycling means can be appropriately selected according to the purpose, and a known conveying means or the like can be used.

  The said control process is a process of controlling each process, and can be performed using a control means. The control means can be appropriately selected according to the purpose, and devices such as a sequencer and a computer can be used.

  The process cartridge used in the present invention is used in the image forming apparatus of the present invention, and includes an electrostatic latent image carrier and at least one unit selected from a developing unit, a charging unit, a transfer unit, and a cleaning unit. It can be attached to and detached from the image forming apparatus main body of the present invention.

Here, FIG. 4A is a schematic configuration diagram of the image forming unit of the electrophotographic image forming apparatus provided with the developing unit of the present invention, and shows the developing unit and the electrostatic latent image carrier. 4B and 4C are a longitudinal sectional view and a transverse sectional view of the developing container.
First, the surface of the rotatable photosensitive member (electrostatic latent image carrier) D is uniformly charged by a charging device (not shown), and then image information corresponding to the content of the original read by an image reading device (not shown). Alternatively, image information sent from the host PC is written by a laser beam from a laser writing device (not shown) to form an electrostatic latent image on the surface.
The developing device 301 realizes visualization of the electrostatic latent image by uniformly supplying toner to the electrostatic latent image carrier (photoconductor) D.
The developing device 301 includes a developer container 302 that stores a developer T composed of toner and a carrier, and a developer supply unit (agitating and conveying) that is disposed in the developer container 302 and supplies the developer to the developing roller 305 by rotating. Means) 303, a screw 304 that is disposed in the developing container 302 and rotates to stir and convey the developer, and an electrostatic latent potential through an opening 302a provided in the developing container 302. A developing roller (developer carrier) 305 that is disposed to face the image carrier D and is rotatably supported, and a new developer containing a carrier is supplied into the developer container 302 via a supply opening 307 provided in the developer container. A storage container 306 (developer cartridge 306a, replenishment roller 306b) to be additionally replenished, and a container for discharging excess developer to the outside of the developer container. Retained and a developer discharging mechanism 320.

The developing roller 305 includes a rotatable developing sleeve 305a disposed and set against the peripheral surface of the photoreceptor D, and a magnetic body having a magnetic pole (not shown) fixedly disposed therein. The magnetic body in the developing roller 305 is necessary to hold the developer on the surface of the developing sleeve 305a, and the doctor blade 312 controls the amount of developer held on the surface of the developing sleeve to an appropriate amount. . The doctor blade 312 is often composed of a plate shape such as stainless steel, and is set at a distance of about 0.2 to 1.2 mm from the surface of the developing sleeve and is uniformly thinned on the developing sleeve 305a. A developer layer is formed, and a uniform developer is supplied to the electrostatic latent image on the photoreceptor D without any unevenness.
A screw (agitating and conveying means) 303 is rotatably supported by a developing container 302 and is rotationally driven by a drive source, and a screw blade projecting spirally on the outer periphery of the rotational shaft 303a. 303b.
A screw (agitating and conveying means) 304 is rotatably supported by the developing container 302 and is rotationally driven by a drive source, and a screw blade 304b that protrudes in a spiral manner outside the rotational shaft 304a. And.
The surplus developer discharging mechanism 320 is provided on the rotating shaft 303a or the rotating shaft 304a of the screw (stirring and conveying means) 303 or 304.
In this embodiment, a configuration example in which the surplus developer discharging mechanism 320 is provided on the rotating shaft 304a of the screw 304 will be mainly described.

The developer T is in a state where a required amount is filled in the developer container 302. First, as the developer supply means 303 for supplying the developer to the vicinity of the developing sleeve 305a and the doctor blade 312, for example, by pushing up or jumping up. A paddle shape that can be supplied may be used, but in this example, it is a screw shape that also has a lateral conveying function.
A screw 304 that stirs and conveys the developer T in a direction opposite to the conveying direction of the screw 303 having a function of supplying the developer T to the developing roller 305 while being agitated and conveyed is rotatably arranged, and is agitated and conveyed by the screws 303 and 304. The developer is configured to move and circulate in the developing container 302 in the directions indicated by arrows A and B.
Further, as a step of supplying a new developer into the developing container 302, an appropriate amount of developer whose supply is controlled from the storage container 306 is supplied into the developing container 302 from the supply opening 307. A discharge port 321 for discharging the developer T surplus due to the replenishment of new developer to the outside of the developing container is disposed outside the developing container 302 at the shaft end of the rotating shaft 304 a of the screw 304. Excess developer discharged from the discharge port 321 is stored in the discharged developer storage container 308, or is transported to the storage container 308 and stored by a separate conveying means (not shown).

FIG. 5 is an external view showing a configuration of an example of the surplus developer discharging mechanism of the present invention. The surplus developer discharging mechanism 320 is provided at the shaft end portion 304A of the rotating shaft 304a of the screw (stirring and conveying means) 304.
The surplus developer discharging mechanism 320 includes a hollow portion 325 provided in a part of the rotating shaft 304a (shaft end portion 304A) of the screw 304, and the hollow portion 325 forms a surplus developer discharging path. is doing. The short shaft portion 304A of the rotating shaft 304a is configured to have a large diameter, the hollow portion 325 is provided inside the end portion of the large diameter shaft, and the discharge port 321 is provided at the shaft end portion of the rotating shaft 304a protruding outside the developing container. ing. The collection port 322 is located inside the developing container.

Next, FIG. 6 shows another example of the image forming apparatus used in the present invention. This image forming apparatus 100C is a tandem type color image forming apparatus. The image forming apparatus 100 </ b> C includes a copying apparatus main body 150, a paper feed table 200, a scanner 300, and an automatic document feeder 400.
The copying apparatus main body 150 is provided with an endless belt-like intermediate transfer member 50 at the center. The intermediate transfer member 50 is stretched around the support rollers 14, 15 and 16 so as to be able to move clockwise in the drawing. An intermediate transfer body cleaning device 17 for removing toner remaining on the intermediate transfer body 50 is disposed in the vicinity of the support roller 15. The intermediate transfer member 50 stretched by the support rollers 14 and 15 is provided with a tandem developing device in which image forming means 18 of four colors of yellow, cyan, magenta, and black are opposed to each other along the conveying direction. 120 is arranged. An exposure device 21 is disposed in the vicinity of the tandem developing device 120. A secondary transfer device 22 is disposed on the side of the intermediate transfer member 50 opposite to the side on which the tandem developing device 120 is disposed. In the secondary transfer device 22, a secondary transfer belt 24, which is an endless belt, is stretched around a pair of rollers 23, and the recording paper conveyed on the secondary transfer belt 24 and the intermediate transfer member 50 can contact each other. It is. A fixing device 25 is disposed in the vicinity of the secondary transfer device 22. The fixing device 25 includes a fixing belt 26 that is an endless belt, and a pressure roller 27 that is pressed against the fixing belt 26.
In the image forming apparatus 100C, a sheet reversing device 28 for reversing the transfer paper is disposed in the vicinity of the secondary transfer device 22 and the fixing device 25. Thereby, images can be formed on both sides of the recording paper.

Next, formation of a full-color image (color copy) using the tandem developing device 120 will be described. First, a document is set on the document table 130 of the automatic document feeder 400, or the automatic document feeder 400 is opened to set a document on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed.
When a start switch (not shown) is pressed, when an original is set on the automatic document feeder 400, after the original is conveyed onto the contact glass 32, on the other hand, when an original is set on the contact glass 32, Immediately, the scanner 300 is driven, and the first traveling body 33 and the second traveling body 34 travel. At this time, the reflected light from the original surface of the light irradiated by the first traveling body 33 is reflected by the mirror in the second traveling body 34 and is received by the reading sensor 36 through the imaging lens 35. As a result, a color original (color image) is read and used as image information for each color of black, yellow, magenta, and cyan. The image information of each color is transmitted to the image forming means 18 of each color in the tandem developing device 120, and a toner image of each color is formed.
The toner image on the black photoconductor 10K, the toner image on the yellow photoconductor 10Y, the toner image on the magenta photoconductor 10M, and the toner image on the cyan photoconductor 10C are sequentially transferred onto the intermediate transfer member 50. (Primary transfer). Then, the toner images of the respective colors are superimposed on the intermediate transfer member 50 to form a composite color image (color transfer image).
As shown in FIG. 7, the image forming means 18 for each color in the tandem developing device 120 is photosensitive on the basis of the photoreceptor 10, the charger 59 for uniformly charging the photoreceptor 10, and the image information of each color. By exposing the body 10 (L in the figure), an exposure device 21 that forms an electrostatic latent image on the photoreceptor 10, and developing the electrostatic latent image using toner of each color, the photoreceptor 10 A developing unit 61 for forming a toner image of each color, a transfer charger 62 for transferring the toner image of each color onto the intermediate transfer member 50, a photoconductor cleaning device 63, and a charge remover 64 are provided.
As the developing means 61, a developing device 301 shown in FIGS. 4A to 4C is used.

On the other hand, in the paper feed table 200, one of the paper feed rollers 142a is selectively rotated to feed recording paper from one of the paper feed cassettes 144 provided in multiple stages in the paper bank 143, and one sheet at a time by the separation roller 145a. The paper is separated and sent to the paper feed path 146, transported by the transport roller 147, guided to the paper feed path 148 in the copying machine main body 150, abutted against the registration roller 49, and stopped. Alternatively, the paper feed roller 142b is rotated to feed out the recording paper on the manual feed tray 52, separated one by one by the separation roller 145b, put into the manual feed path 53, and abutted against the registration roller 49 and stopped. The registration roller 49 is generally used while being grounded, but may be used in a state where a bias is applied to remove paper dust from the sheet.
Then, the registration roller 49 is rotated in time with the color transfer image formed on the intermediate transfer member 50, and the recording paper is fed between the intermediate transfer member 50 and the secondary transfer device 22 to be printed on the recording paper. A color transfer image is formed. The toner remaining on the intermediate transfer member 50 after the transfer is cleaned by the intermediate transfer member cleaning device 17.
The recording paper on which the color transfer image is formed is conveyed to the fixing device 25 by the secondary transfer device 22, and the color transfer image is fixed on the recording paper by heat and pressure. Thereafter, the recording sheet is switched by the switching claw 55 and discharged by the discharge roller 56 and is stacked on the discharge tray 57. Alternatively, the sheet is switched by the switching claw 55 and reversed by the sheet reversing device 28 and led to the transfer position again. After an image is also formed on the back surface, the sheet is discharged by the discharge roller 56 and stacked on the discharge tray 57.

  In the image forming method and the image forming apparatus of the present invention, even if the toner is subjected to stress such as pressure and heat by the transfer means for transferring the developer from the storage container to the developing container, the toner loose aggregate is not formed, The occurrence of so-called “fireflies” that are abnormal images can be suppressed.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
In the following examples and comparative examples, “toner volume average particle diameter (Dv) and ratio (Dv / Dn)”, “ratio of particles having a particle diameter of 2 μm or less and average circularity”, and “bulk density of fine particles” are: Measurement was performed as follows.

<Measurement of Volume Average Particle Size (Dv) and Ratio (Dv / Dn) of Toner>
The volume average particle diameter (Dv) and the number average particle diameter (Dn) of the toner are measured with a particle size measuring device (“Multisizer III”, manufactured by Beckman Coulter, Inc.) with an aperture diameter of 100 μm, and analysis software (Beckman Coulter Multisizer 3) is used. The analysis was performed at Version 3.51). Specifically, 0.5 ml of 10% by weight surfactant (alkylbenzene sulfonate, Neogen SC-A; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is added to a 100 ml glass beaker, and 0.5 g of each toner is added. Next, 80 ml of ion-exchanged water was added. The obtained dispersion was subjected to a dispersion treatment for 10 minutes with an ultrasonic disperser (W-113MK-II, manufactured by Honda Electronics Co., Ltd.). The dispersion was measured using the Multisizer III and Isoton III (manufactured by Beckman Coulter, Inc.) as the measurement solution. In the measurement, the toner sample dispersion was dropped so that the concentration indicated by the apparatus was 8 ± 2%. In this measurement method, it is important to adjust the concentration to 8 ± 2% from the viewpoint of the reproducibility of the particle size. Within this concentration range, no error occurs in the particle size.

<Percentage of particles having a particle size of 2 μm or less and average circularity>
The ratio of particles having a particle diameter of 2 μm or less and the average circularity of the toner were measured by a flow type particle image analyzer FPIA-2000 (manufactured by Sysmex Corporation). As a specific measurement method, 0.1 to 0.5 ml of a surfactant (alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance, and a measurement sample is further added. About 0.1 to 0.5 g was added. The suspension in which the sample was dispersed was obtained by performing dispersion treatment for 1 to 3 minutes with an ultrasonic disperser, and measuring the shape and distribution of the toner with the above apparatus at a dispersion concentration of 3000 to 10,000 / μl.

<Measurement of bulk density of fine particles>
The bulk density of the fine particles was measured by the following method. Using a 100 ml graduated cylinder, fine particles were gradually added to make 100 ml.
At that time, no vibration was applied. The bulk density was measured by the difference in mass before and after putting the fine particles of the graduated cylinder.
Bulk density (g / cm ³ ) = fine particle amount (g / 100 ml) ÷ 100

Example 1
<Production of toner>
-Synthesis of unmodified polyester resin-
In a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, 229 parts by mass of bisphenol A ethylene oxide 2 mol adduct, 529 parts by mass of bisphenol A propion oxide 3 mol adduct, 208 parts by mass of terephthalic acid, 46 adipic acid 46 Part by mass and 2 parts by mass of dibutyltin oxide were added and reacted at 230 ° C. for 8 hours under normal pressure. Next, after reacting under reduced pressure of 10 to 15 mmHg for 5 hours, 44 parts by weight of trimellitic anhydride was added to the reaction vessel, and reacted at 180 ° C. under normal pressure for 2 hours to obtain an unmodified polyester resin (1 ) Was synthesized.
The obtained unmodified polyester resin (1) had a number average molecular weight of 2,500, a mass average molecular weight of 6,700, a glass transition temperature of 43 ° C., and an acid value of 25 mgKOH / g.

-Manufacture of master batch-
1200 parts by weight of water, 540 parts by weight of carbon black (Printtex 35, manufactured by Dexa, DBP oil absorption = 42 ml / 100 mg, pH = 9.5) and 1200 parts by weight of unmodified polyester resin were mixed with Henschel mixer (Mitsui Mining Co., Ltd.). ) And mixed. The resulting mixture was kneaded at 150 ° C. for 30 minutes using two rolls, then rolled and cooled, and pulverized with a pulverizer (manufactured by Hosokawa Micron Corporation) to prepare a master batch (1).

-Preparation of wax dispersion-
In a reaction vessel in which a stirring bar and a thermometer were set, 378 parts by mass of unmodified polyester resin (1), 110 parts by mass of carnauba wax, 22 parts by mass of a salicylic acid metal complex (E-84, manufactured by Orient Chemical Industry Co., Ltd.), And 947 mass parts of ethyl acetate was prepared, and it heated up to 80 degreeC under stirring, and hold | maintained at 80 degreeC for 5 hours, Then, it cooled to 30 degreeC over 1 hour. Next, 500 parts by mass of master batch (1) and 500 parts by mass of ethyl acetate were charged into the reaction vessel, and mixed for 1 hour to prepare a raw material solution (1).
1324 parts by mass of the obtained raw material solution (1) was transferred to a reaction vessel and filled with 80% by volume of 0.5 mm zirconia beads using an ultra visco mill (manufactured by Imex Co., Ltd.) as a bead mill. When the disk peripheral speed is 6 m / sec, 3 passes are performed. I. Pigment red and carnauba wax were dispersed to prepare a wax dispersion liquid (1).

-Preparation of dispersion of toner material-
Next, 1324 parts by mass of a 65% by mass ethyl acetate solution of the unmodified polyester resin (1) was added to the wax dispersion (1). A layered inorganic mineral montmorillonite (Clayton APA, at least partly modified with a quaternary ammonium salt having a benzyl group) was added to 200 parts by mass of a dispersion obtained by one pass using Ultraviscomil under the same conditions as above. (Soutern Clay Products) 1.0 part by mass was added. K. Using a homodisper (manufactured by Tokushu Kika Kogyo Co., Ltd.), the mixture was stirred for 30 minutes to obtain a dispersion (1) of toner material.

-Synthesis of intermediate polyester resin-
In a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, 682 parts by mass of bisphenol A ethylene oxide 2 mol adduct, 81 parts by mass of bisphenol A propylene oxide 2 mol adduct, 283 parts by mass of terephthalic acid, 22 parts by mass of merit acid and 2 parts by mass of dibutyltin oxide were charged and reacted at 230 ° C. for 8 hours under normal pressure. Next, it was made to react under reduced pressure of 10-15 mmHg for 5 hours, and the intermediate polyester resin was synthesize | combined.
The obtained intermediate polyester resin had a number average molecular weight of 2,100, a weight average molecular weight of 9,500, a glass transition temperature of 55 ° C., an acid value of 0.5 mgKOH / g, and a hydroxyl value of 51 mgKOH / g. .

-Synthesis of prepolymer-
Next, 410 parts by mass of the intermediate polyester resin, 89 parts by mass of isophorone diisocyanate, and 500 parts by mass of ethyl acetate were charged in a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen introduction pipe, and reacted at 100 ° C. for 5 hours. The prepolymer (1) was synthesized. The free isocyanate content of the obtained prepolymer (1) was 1.53% by mass.

-Preparation of oil phase mixture-
In a reaction vessel equipped with a stir bar and a thermometer, 170 parts by mass of isophoronediamine and 75 parts by mass of methyl ethyl ketone were charged and reacted at 50 ° C. for 5 hours to synthesize a ketimine compound. The amine value of the obtained ketimine compound was 418 mgKOH / g.
In a reaction container, 749 parts by mass of a dispersion of toner material (1), 115 parts by mass of prepolymer (1), and 2.9 parts by mass of a ketimine compound were charged, and a TK homomixer (manufactured by Tokushu Kika Co., Ltd.) was added. The resulting mixture was mixed at 5,000 rpm for 1 minute to obtain an oil phase mixture (1).
The Casson yield value at 25 ° C. of the obtained oil phase mixture (1) was measured as follows. The results are shown in Table 1.

<Casson yield measurement method>
The Casson yield value of the obtained oil phase mixture (1) was measured using a high shear viscometer.
The measurement conditions are as follows.
Device: AR2000 (TA Instruments)
Shear stress: 120 Pa / 5 min Geometry: 40 mm steel plate Geometry gap: 1 mm
Analysis software: TA DATA ANALYSIS (TA Instruments)

-Polymerization of resin particle dispersion-
In a reaction vessel in which a stir bar and a thermometer are set, 683 parts by mass of water, reactive emulsifier (sulfuric ester sodium salt of methacrylic acid ethylene oxide adduct, Eleminol RS-30, Sanyo Chemical Industries, Ltd.) 11 mass Part, 83 parts by mass of styrene, 83 parts by mass of methacrylic acid, 110 parts by mass of butyl acrylate, and 1 part by mass of ammonium persulfate were stirred for 15 minutes at 400 rpm to obtain an emulsion. The emulsion was heated, heated to 75 ° C. and reacted for 5 hours. Next, 30 parts by mass of a 1% by mass ammonium persulfate aqueous solution was added and aged at 75 ° C. for 5 hours to prepare a resin particle dispersion.

-Preparation of emulsified slurry-
990 parts by weight of water, 83 parts by weight of a resin particle dispersion, 37 parts by weight of an aqueous 48.5% by weight solution of sodium dodecyl diphenyl ether disulfonate, Eleminol MON-7 (manufactured by Sanyo Chemical Industries), 1 of sodium carboxymethylcellulose polymer dispersant A mass medium aqueous solution (Serogen BS-H-3, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 135 parts by mass and ethyl acetate 90 parts by mass were mixed and stirred to prepare an aqueous medium.
To 1,200 parts by mass of the aqueous medium, 867 parts by mass of the oil phase mixed solution was added and mixed for 20 minutes at 13,000 rpm using a TK homomixer to prepare a dispersion (emulsion slurry).

  Next, the emulsified slurry (1) is charged into a reaction vessel equipped with a stirrer and a thermometer, and after removing the solvent at 30 ° C. for 8 hours, aging is carried out at 45 ° C. for 4 hours to obtain the dispersed slurry (1). Produced.

After 100 parts by mass of the obtained dispersion slurry (1) was filtered under reduced pressure, 100 parts by mass of ion-exchanged water was added to the filter cake, mixed at 12,000 rpm for 10 minutes using a TK homomixer, and then filtered.
To the obtained filter cake, 10% by mass hydrochloric acid was added to adjust the pH to 2.8, followed by mixing at 12,000 rpm for 10 minutes using a TK homomixer, followed by filtration.
Further, 300 parts by mass of ion-exchanged water was added to the obtained filter cake, and after mixing for 10 minutes at 12,000 rpm using a TK homomixer, the operation of filtering was performed twice to prepare the final filter cake.
The obtained final filter cake was dried at 45 ° C. for 48 hours using an air circulation dryer, and sieved with a mesh having a mesh size of 75 μm to prepare toner base particles.

Next, 1.0 mass of silica having a large particle diameter (BET specific surface area of 21 m ² / g, water content of 0.4%, bulk density of 140 g / L) is used as an external additive with respect to 100 parts by mass of the obtained toner base particles. Parts, small particle size silica (BET specific surface area 140 m ² / g, water content 0.4%, bulk density 140 g / L) 1.5 parts by mass, hydrophobized titanium oxide 0.5 parts by mass, silica gel (BET A toner was prepared by adding 3.0 parts by mass of a specific surface area of 600 m ² / g, a water content of 1.0%, and a bulk density of 740 g / L, and mixing the mixture using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.).

-Production of developer-
Next, 5% by mass of each toner subjected to external additive treatment and 95% by mass of a copper-zinc ferrite carrier having a flat particle diameter of 40 μm coated with a silicone resin are rolled and stirred. A two-component developer was prepared by uniformly mixing and charging using a blur mixer.

<Image evaluation>
Image formation was performed using the image forming apparatus 100 shown in FIGS. In the image forming apparatus shown in FIGS. 6 and 7, as the developing means 61, the developing means 301 shown in FIGS. 4A to 4C is used.

(1) The container 306 was filled with the toner of Example 1, the developer of Example 1, and airgel having a particle diameter of 0.88 mm as porous particles to prepare a premix toner (replenishment toner). However, the mixing ratio of the airgel was 15% by volume with respect to the toner in the premix toner.
(2) The toner used for evaluation and the image forming apparatus were all left for 1 day in an environment of 25 ° C. and 50%. That is, a storage container filled with toner or the like was mounted on the image forming apparatus and left for 1 day at 25 ° C. and 50% environment.
(3) 28 g of the replenishing toner is charged from the storage container 306 into the developing container 302 that has formed an image and consumed the toner (which has become a carrier and porous particles), and 400 g of the developer having a toner concentration of 7%. Produced.
(4) The developing container 302 was mounted on the main body of the image forming apparatus 100, the developing roller 305 was operated at a linear speed of 300 mm / s, and only the developing unit 301 was idled for 5 minutes.
(5) Both the developing roller 305 and the photosensitive member D are rotated by trailing at a target linear speed, and the charging potential and the developing bias are set so that the toner on the photosensitive member D becomes 0.4 ± 0.05 mg / cm ^2. Adjusted.
(6) Under the above development conditions, the transfer current was adjusted so that the transfer rate was 96 ± 2%.
(7) 10,000 continuous monochrome images were output.
(8) The image quality (the number of fireflies) was evaluated as follows for the single-color solid image output after outputting 10,000 sheets. Moreover, various characteristics were evaluated as follows. The results are shown in Table 1.

<Evaluation of the number of fireflies>
For a single color solid image (toner adhesion amount of 0.45 mg / cm ² ) formed on a recording medium, when a dark color point is formed in comparison with the solid image density, an abnormality having a light color gamut around the dark color point The criterion for evaluating the number of images (fireflies) was 2 or less, and NG when the number was more than 2.

<Toner scattering>
Toner scattering was evaluated according to the following criteria.
〔Evaluation criteria〕
○: No toner scattering and very good △: Slightly toner scattering and image quality is slightly poor ×: Toner scattering is very large and appears remarkably in image quality

<Evaluation of pump clogging>
When the image forming apparatus was used under standard conditions and the image forming apparatus stopped due to clogging of the pump, it was determined as NG, and other cases were determined as OK.

<Cleanability>
The cleaning property was evaluated according to the following criteria.
〔Evaluation criteria〕
◎: Extremely good ○: Good △: Somewhat bad ×: Bad

(Example 2)
In Example 1, the toner and developer were prepared in the same manner as in Example 1 except that the amount of the modified layered inorganic mineral (trade name: Clayton APA) was changed from 1.7 parts by mass to 1.3 parts by mass. Produced.
Next, using the produced toner and developer, the airgel is changed to silica gel (particle size 0.92 mm), and the mixing ratio of the silica gel is changed from 15% by volume to 10% by volume with respect to the toner in the premix toner. Except that, image evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
In Example 1, except that the amount of the modified layered inorganic mineral (trade name: Kraton APA) was changed from 1.7 parts by mass to 1.0 part by mass, the toner and developer were changed in the same manner as in Example 1. Produced.
Next, image evaluation was performed in the same manner as in Example 1 except that the airgel was changed to zeolite (particle size: 0.77 mm) using the toner and developer thus produced. The results are shown in Table 1.

(Comparative Example 1)
Using the same toner and developer as in Example 1, airgel (particle size 0.88 mm) was changed to airgel (particle size 1.8 mm), and the mixing ratio of the airgel was 15 volumes with respect to the toner in the premix toner. Image evaluation was performed in the same manner as in Example 1 except that the volume was changed from% to 10% by volume. The results are shown in Table 1.

(Comparative Example 2)
In Example 1, the toner and developer were prepared in the same manner as in Example 1 except that the amount of the modified layered inorganic mineral (trade name: Clayton APA) was changed from 1.7 parts by mass to 1.3 parts by mass. Produced.
Next, image evaluation was performed in the same manner as in Example 1 except that the airgel was changed to zeolite (particle size: 1.6 mm) using the produced toner and developer. The results are shown in Table 1.

(Comparative Example 3)
In Example 1, the toner and developer were prepared in the same manner as in Example 1 except that the amount of the modified layered inorganic mineral (trade name: Clayton APA) was changed from 1.7 parts by mass to 1.3 parts by mass. Produced.
Next, image evaluation was performed in the same manner as in Example 1 except that the airgel was changed to zeolite (particle size: 2.2 mm) using the produced toner and developer. The results are shown in Table 1.

(Comparative Example 4)
<Production of toner by kneading and grinding method>
A toner composition having the following composition is sufficiently mixed with a blender and then melt-kneaded with a biaxial extruder (kneading temperature: 140 ° C., extrusion speed: 10 kg / hour, rolling gap: 2 mm, standing time until grinding: 48 hours) Then, this was pulverized and classified to prepare a base toner having a volume average particle size of 7.3 μm.
With respect to 100 parts by mass of the obtained base toner, 1.0 part by mass of a large particle size silica (BET specific surface area 21 m ² / g, water content 0.4%, bulk density 140 g / L) as an external additive is small. Particle size silica (BET specific surface area 140 m ² / g, water content 0.4%, bulk density 140 g / L) 1.5 parts by mass, hydrophobized titanium oxide 0.5 parts by mass, silica gel (BET specific surface area 600 m ² / G, moisture content of 1.0%, bulk density of 740 g / L) and 15 parts by mass, and a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) is used for mixing treatment to produce a toner. Thus, a developer was prepared.
-Toner composition-
Crystalline polyester resin: 35 parts by mass Amorphous polyester resin: 65 parts by mass Polyparaffin wax (melting point: 151 ° C.): 5 parts by mass Charge control agent (metal salt of salicylic acid derivative) ... 2 parts by mass-Colorant (carbon black) ... 6 parts by mass-Stearic acid amide compound (melting point: 115 ° C) ... 5 parts by mass

  Next, image evaluation was performed in the same manner as in Example 1 except that the mixing ratio of the airgel was changed from 15% by volume to 20% by volume with respect to the toner in the premixed toner using the produced toner and developer. went. The results are shown in Table 1.

(Comparative Example 5)
Using the same toner and developer as in Comparative Example 4, the airgel was changed to silica gel (particle size 0.92 mm), and the mixing ratio of the silica gel was changed from 15 vol% to 25 vol% with respect to the toner in the premix toner. Except for the above, image evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 6)
Using the same toner and developer as in Comparative Example 4, the airgel was changed to zeolite (particle size 0.77 mm), and the mixing ratio of the zeolite was changed from 15% by volume to 30% by volume with respect to the toner in the premix toner. Except that, image evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

From the results in Table 1, it was found that Examples 1 to 3 were free from clogging of the pump and could suppress the occurrence of “fireflies” that are abnormal images.
On the other hand, in Comparative Examples 1 to 3, pump clogging occurred, and in Comparative Examples 4 to 6, it was found that there was a problem in image quality due to toner scattering.

  The image forming apparatus and the image forming method of the present invention are suitable for an electrophotographic laser printer, a digital copying machine, a full color copying machine, a full color laser printer, and the like.

FIG. 1 is a schematic diagram illustrating an example of a general toner transfer device (toner supply device). FIG. 2 is a sectional view of the powder pump means. FIG. 3 is a diagram schematically showing the shape of the toner. FIG. 4A is a schematic configuration diagram of an image forming unit of the electrophotographic image forming apparatus of the present invention. FIG. 4B is a longitudinal sectional view of the developing container. FIG. 4C is a cross-sectional view of the developing container. FIG. 5 is an external view showing the configuration of an example of the surplus developer discharging means in the image forming apparatus of the present invention. FIG. 6 is a schematic view showing an example of the image forming apparatus of the present invention. FIG. 7 is an enlarged view of the image forming unit in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 201 Developing apparatus 202 Powder pump means 203 Toner storage container 204 Uniaxial eccentric powder pump 205 Rotor 206 Stator 207 Holder 208 Gear 209 Joint 301 Developing apparatus 302 Developer container 303 Developer supply means (agitating and conveying means)
304 Screw 305 Development roller 306 Storage container 306a Developer cartridge 306b Supply roller 307 Supply opening 308 Discharged developer storage container 312 Doctor blade 320 Excess developer discharge mechanism 321 Discharge port 322 Collection port 325 Hollow part D Photoconductor T Toner

Claims (11)

An electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier;
A developing step of developing the electrostatic latent image using a toner contained in a developing container to form a visible image;
A transfer step of transferring the visible image to a recording medium;
A fixing step of fixing the transferred image transferred to the recording medium;
A toner transfer step of supplying replenishment toner stored in a storage container from the storage container to the developing container in accordance with the amount of toner consumed during image formation;
An image forming method including a surplus developer discharging step of discharging surplus developer remaining in the developing container due to replenishment of the replenishing toner in the toner transfer step to the outside of the developing container,
As the replenishment toner, a premix toner in which a toner and a carrier are mixed at a certain ratio is used, and contains 10% by volume to 15% by volume of porous particles having a particle diameter of 1 mm or less with respect to the toner in the premix toner. An image forming method.   The image forming method according to claim 1, wherein an airgel is used as the porous particles.   In an organic solvent, a prepolymer containing a binder resin and a modified polyester resin, a compound that extends or crosslinks with the prepolymer, a colorant, a release agent, and at least part of interlayer ions in the layered inorganic mineral From a dispersion obtained by dissolving or dispersing a modified layered inorganic mineral modified with organic ions and having a Casson yield value at 25 ° C. of 1 Pa to 100 Pa, or by crosslinking or extending the dispersion in an aqueous medium. The image forming method according to claim 1, wherein a toner obtained by removing the solvent is used.   The image forming method according to claim 3, wherein the content of the modified layered inorganic mineral is 0.05% by mass to 10% by mass with respect to the solid content in the solution or dispersion.   The image forming method according to claim 1, wherein a toner having an average circularity of 0.94 to 0.99 is used.   A toner having a volume average particle diameter of 3 μm to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of 1.00 to 1.30 is used. Item 6. The image forming method according to any one of Items 1 to 5.   7. The image forming method according to claim 1, wherein a toner having a ratio of particles having a particle diameter of 2 μm or less of 1% by number to 10% by number is used. 8. The toner according to claim 1, wherein a toner obtained by externally adding fine particles having an average primary particle diameter of 50 nm to 500 nm and a bulk density of 0.3 g / cm ³ or more is used on the surface of the toner base particles. Image forming method. An electrostatic latent image carrier, and electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier;
A developing unit having a stirring and conveying mechanism that develops the electrostatic latent image using a toner contained in a developing container to form a visible image;
Transfer means for transferring the visible image to a recording medium;
Fixing means for fixing the transferred image transferred to the recording medium;
Toner transfer means for replenishing the replenishment toner stored in the storage container from the storage container to the developing container according to the amount of toner consumed in the image formation;
An image forming apparatus having surplus developer discharging means for discharging surplus developer that has become surplus in the developing container due to replenishment of replenishing toner in the toner transfer step;
The replenishing toner is a premix toner in which a toner and a carrier are mixed at a constant ratio, and contains 10% by volume to 15% by volume of porous particles having a particle diameter of 1 mm or less with respect to the toner in the premix toner. An image forming apparatus.   The image forming apparatus according to claim 9, wherein the toner transfer unit is a screw pump.   11. A process cartridge having an electrostatic latent image carrier and at least one unit selected from a developing unit, a charging unit, a transfer unit, and a cleaning unit is detachable from the main body of the image forming apparatus. The image forming apparatus described in 1.