JP5617579B2 - Image forming apparatus, image forming method, and process cartridge - Google Patents

Description

  The present invention relates to an image forming apparatus, an image forming method, and a process cartridge, such as a copying machine, a printer, a facsimile machine, or a complex machine using an electrophotographic system.

In recent electrophotographic image forming apparatuses, high image quality and high durability are also desired. In other words, there is little change in image quality due to environmental fluctuations, and a stable image must be provided over time.
Further, further speeding up is increasing as a market demand. Conventionally, a two-component developer composed of a non-magnetic toner and a magnetic carrier is held on a developer carrier, a magnetic brush is formed by a magnetic pole contained therein, and a photosensitive member (hereinafter referred to as “electrophotographic photosensitive member”) is formed on the developer carrier. And a method of performing development by applying a developing bias at a position opposite to the body, the photosensitive member, the electrostatic latent image carrier, and the image carrier. . This method is generally used for development of an electrostatic copying machine for reasons such as excellent durability and image characteristics, but it cannot cope with high speed, high density, and stabilization of image density over time.

As a developing method corresponding to the recent increase in speed and density, a multistage developing method has been proposed. The reason for adopting such a method is to prevent a decrease in image density in a solid image. Therefore, this is a system in which a plurality of developing sleeves are arranged in multiple stages.
In the multi-stage development method, the magnetic brush is formed such that a plurality of magnetic brushes in contact with the image carrier are arranged in parallel in the rotation direction of the image carrier, and a developing operation for one latent image is performed a plurality of times. Thus, it is aimed that sufficient toner adheres to the solid image. In other words, the development time for one latent image becomes longer, and an attempt is made to provide a margin for toner supply.
However, the occurrence of abnormal images such as white spots at the rear end is still not suppressed. In order to suppress abnormal images such as trailing edge blanks, for example, in conventional multi-stage development, measures such as reducing the developing sleeve diameter have been taken. By reducing the diameter of the developing sleeve (for example, 16 mm in diameter), the half width of the magnetic brush is narrowed. Therefore, at the same time as the developing nip is shortened, the length of the head of the magnetic brush in the developing portion is actually shortened, so that the margin at the trailing edge is improved. However, with a small-diameter developing sleeve, there is also a problem that it is difficult to design a developer cutting edge. This becomes a factor of reducing the solid image following performance, which is a problem of high-speed development.
Further, since the developing sleeve must be rotated at a high speed, the margin for carrier scattering and the like is also reduced.
In addition, since the load on the drive system also increases, a decrease in durability due to an increase in torque and generation of vibrations are brought up as new problems. Therefore, it becomes difficult to cope with further speeding up.

In order to stabilize the image density, for example, in Patent Document 1, in the two-stage development system that outputs a single color image by the one-component development system, the interval between the photoreceptor and the developing sleeve is set at the upstream side in the movement direction of the photoreceptor. The second developing sleeve located on the downstream side in the moving direction of the photosensitive member is made wider than that of the first developing sleeve located in the first position. By adopting such a configuration, white spots are improved.
However, since the first developing sleeve and the second developing sleeve rotate in the same direction as the moving direction of the photosensitive member, the halo (half-tip white spot) generated in the first developing sleeve is removed from the second developing sleeve. There is a problem that the development sleeve further deteriorates.

In Patent Document 2, two developing chambers are provided along the rotation direction of the photosensitive drum, the two-component developer is accommodated in the developing chamber on the upstream side in the latent image moving direction, and the electrostatic chamber formed on the photosensitive drum. The latent image is developed with a two-component magnetic brush development. The developing chamber on the downstream side is a one-component developing system and includes an elastic roller as a toner supply member, and develops the same latent image by non-magnetic one-component development. Thus, there has been proposed an image forming apparatus that can prevent problems such as improvement in developability and white-out at the rear end and can prevent the carrier in the developer from scavenging. By adopting such a configuration, the trailing edge white spot is improved.
However, since the downstream side is set to one-component jumping development, the high-speed machine has problems such as toner scattering.
Further, because of the elastic roller, the durability is inferior compared to a two-component multi-stage development metal (aluminum, etc.) sleeve. Therefore, there is a problem that it is difficult to achieve both high-speed compatibility and durability of multistage development.

Further, in Patent Document 3, the half-value width of the normal magnetic flux density of the developing pole contained in the developing carrier on the downstream side in the electrostatic latent image moving direction is larger than the half-value width of the normal magnetic flux density of the upstream developing pole. It is configured to be narrow.
By adopting such a configuration, it is possible to suppress abnormal images such as white spots at the trailing edge of the halftone while achieving high-speed compatibility and durability, which are essential requirements for multistage development.
However, in such a configuration, since the half-value width of the normal magnetic flux density of the downstream development pole is narrower than that of the upstream side, the magnetic brush spikes just before and immediately after development in the downstream development region. Abruptly occurs, and toner scattering occurs at that time.

In Patent Document 4, the first developing member and the second developing member that rotate in the same direction as the image carrier are provided, and the average crest interval Sm1 on the surface of the first developing member, the surface of the second developing member. The relationship between the average peak interval Sm2 and the weight average particle diameter D of the carrier is Sm2 <D ≦ Sm1.
By adopting such a configuration, it is possible to prevent two phenomena such as contamination due to toner fusion to the developing means and degradation of image quality.
However, since the first developing member and the second developing member rotate in the same direction as the image carrier, the second developing member can improve the halo (half-point white spot) generated in the first developing member. There is a risk of further worsening. In addition, since the average crest interval Sm2 on the surface of the second developing member is made smaller than the weight average particle diameter D of the carrier, the first toner is formed with respect to the solid toner image formed on the image carrier by the first developing member. When scavenging by the magnetic brush formed on the second developing member is performed, the magnetic brush becomes slippery on the second developing member, so that scavenging is insufficient and the uniformity of the solid image is impaired. There is a problem of being. In regard to toner fusion to the developing means, which is a problem in Patent Document 4, the first developing member and the second developing member as in the present invention rotate in opposite directions, and the first developing member is an image. There is no problem with the method of rotating in the direction opposite to the carrier.

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention is capable of forming a high-quality image that suppresses abnormal images such as halos and solid image density unevenness, and can satisfy the original multi-stage development requirements of achieving high-speed compatibility and durability. An object is to provide an image forming method and a process cartridge.

Means for solving the problems are as follows. That is,
<1> An image carrier, a charging unit that charges the surface of the image carrier, an exposure unit that exposes the charged image carrier surface to form an electrostatic latent image, and the electrostatic latent image is converted into a toner. And an image forming apparatus having at least a developing unit that forms a visible image by developing using a developer containing a carrier,
The developing means includes at least a first developing member and a second developing member, the first developing member and the second developing member rotate in opposite directions, and the first developing member is Rotating in the opposite direction to the image carrier, the average crest distance on the surface of the first developing member is Sm1, the average crest distance on the surface of the second developing member is Sm2, and the weight average particle diameter of the carrier of the developer is D. In this case, the image forming apparatus satisfies the following expression: Sm1 ≦ D ≦ Sm2.
<2> The toner dissolves or disperses at least a compound having an active hydrogen group, a polymer having a site capable of reacting with the compound having an active hydrogen group, a polyester resin, a colorant, and a release agent in an organic solvent. The image forming apparatus according to <1>, which is obtained by reacting the toner material liquid thus obtained in an aqueous medium.
<3> The image forming apparatus according to <2>, wherein the toner has a weight average particle diameter of 2 μm to 6 μm.
<4> The image forming apparatus according to any one of <1> to <3>, wherein the image forming apparatus is a tandem type in which a plurality of image forming elements including at least an image carrier, a charging unit, and a developing unit are arranged.
<5> The image forming apparatus according to any one of <1> to <4>, wherein the charging unit applies a DC voltage on which an alternating voltage is superimposed.
<6> The image forming apparatus according to any one of <1> to <5>, wherein the charging unit is in the form of a roller and is disposed in proximity to and non-contact with the image carrier.
<7> A charging step for charging the surface of the image carrier, an exposure step for exposing the charged surface of the image carrier to form an electrostatic latent image, and a developer containing the electrostatic latent image and a toner and a carrier. An image forming method including at least a development step of developing a visible image by developing using
The developing step includes at least a first developing member and a second developing member, the first developing member and the second developing member rotate in opposite directions, and the first developing member is Rotating in the opposite direction to the image carrier, the average crest distance on the surface of the first developing member is Sm1, the average crest distance on the surface of the second developing member is Sm2, and the weight average particle diameter of the carrier of the developer is D. In this case, the image forming method is performed using a developing unit that satisfies the following formula: Sm1 ≦ D ≦ Sm2.
<8> An image carrier and at least developing means for developing the electrostatic latent image formed on the image carrier using a developer containing toner and a carrier to form a visible image, A process cartridge removable from the main body of the forming apparatus,
The developing means includes at least a first developing member and a second developing member, the first developing member and the second developing member rotate in opposite directions, and the first developing member is Rotating in the opposite direction to the image carrier, the average crest distance on the surface of the first developing member is Sm1, the average crest distance on the surface of the second developing member is Sm2, and the weight average particle diameter of the carrier of the developer is D. In this case, the process cartridge satisfies the following expression: Sm1 ≦ D ≦ Sm2.

  According to the present invention, it is possible to solve the above-described problems and achieve the object, and to form a high-quality image that suppresses abnormal images such as halo and solid image density unevenness, as well as high-speed compatibility and durability. Therefore, it is possible to provide an image forming apparatus, an image forming method, and a process cartridge capable of satisfying the original requirement of multi-stage development for achieving high performance.

FIG. 1 is a schematic diagram showing the configuration of the developing means used in the image forming apparatus of the present invention. FIG. 2 is a drawing showing a method for measuring the average crest spacing Sm of the developing sleeve. FIG. 3 is a schematic view showing an example of the image forming apparatus of the present invention. FIG. 4 is a schematic view showing an example of a tandem full-color electrophotographic image forming apparatus according to the present invention.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention includes at least an image carrier, a charging unit, an exposure unit, and a developing unit, and other units appropriately selected as necessary, for example, a fixing unit and a cleaning unit. , Static elimination means, recycling means, control means and the like.
The image forming method of the present invention includes at least a charging step, an exposure step, and a development step, and further other steps appropriately selected as necessary, for example, a fixing step, a cleaning step, a static elimination step, a recycling step, and a control step. Etc.

  The image forming method of the present invention can be preferably carried out by the image forming apparatus of the present invention, the charging step can be performed by the charging unit, the exposure step can be performed by the exposing unit, The developing step can be performed by the developing unit, and the other steps can be performed by the other unit.

<Image carrier>
The material, shape, structure, size and the like of the image carrier are not particularly limited and can be appropriately selected according to the purpose. Examples of the shape include a drum shape, a sheet shape, and an endless shape. Examples include a belt shape. The structure may be a single-layer structure or a laminated structure, and the size may be appropriately selected according to the size and specifications of the image forming apparatus. Examples of the material include inorganic photoreceptors such as amorphous silicon, selenium, CdS, and ZnO; organic photoreceptors (OPC) such as polysilane and phthalopolymethine, and the like.

  For example, the amorphous silicon photosensitive member is heated to 50 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, or the like is applied on the support. A photosensitive layer made of a-Si is formed by a film forming method. Among these, the plasma CVD method is particularly preferable, and specifically, a method in which the source gas is decomposed by direct current, high frequency, or microwave glow discharge to form a photosensitive layer made of a-Si on the support is preferable. .

The organic photoreceptor (OPC) has (1) optical characteristics such as a wide light absorption wavelength range and a large amount of light absorption, (2) electrical characteristics such as high sensitivity and stable charging characteristics, (3) In general, it is widely applied because of the wide selection range of materials, (4) ease of production, (5) low cost, and (6) non-toxicity. The layer structure of such an organic photoreceptor is roughly divided into a single layer structure and a laminated structure.
The single-layered photoreceptor has a support and a single-layer type photosensitive layer provided on the support, and further includes a protective layer, an intermediate layer, and other layers as necessary.
The laminated structure of the photoreceptor comprises a support, and a laminate type photosensitive layer having at least a charge generation layer and a charge transport layer in this order on the support, and further includes a protective layer and an intermediate layer as necessary. And other layers.

<Charging step and charging means>
The charging step is a step of charging the surface of the image carrier, and is performed by the charging unit.
The charging means is not particularly limited as long as it can apply a voltage to the surface of the image carrier to uniformly charge the surface, and can be appropriately selected according to the purpose. There are roughly divided into a contact-type charging means for charging in contact with the image carrier and (2) a non-contact-type charging means for charging in a non-contact manner with the image carrier.

-Contact charging means-
Examples of the contact type charging means (1) include a conductive or semiconductive charging roller, a magnetic brush, a fur brush, a film, and a rubber blade. Among these, the charging roller can greatly reduce the amount of ozone generated compared to corona discharge, and is excellent in stability when the image carrier is repeatedly used, and is effective in preventing image quality deterioration.
The magnetic brush includes a non-magnetic conductive sleeve that supports various ferrite particles such as Zn-Cu ferrite, and a magnet roll included in the sleeve. The fur brush is formed by, for example, winding or pasting a fur treated with carbon, copper sulfide, metal, metal oxide, or the like around a metal or a treated metal core.

-Non-contact charging means-
The non-contact charging means (2) includes, for example, a non-contact charger using a corona discharge, a needle electrode device, a solid discharge element; Examples thereof include a conductive charging roller.

The corona discharge is a non-contact charging method that gives positive or negative ions generated by corona discharge in the air to the surface of the image carrier, and a coroton charger having a characteristic of giving a constant amount of charge to the image carrier. And a scorotron charger having the characteristic of giving a constant potential.
The coroton charger is composed of a casing electrode that occupies a half space around the discharge wire, and a discharge wire placed almost at the center thereof.
The scorotron charger is obtained by adding a grid electrode to the corotron charger, and the grid electrode is provided at a position 1.0 mm to 2.0 mm away from the surface of the image carrier.
The charging roller disposed with a minute gap with respect to the image carrier is an improvement of the charging roller so as to have a minute gap with respect to the image carrier. The fine gap is preferably 10 μm to 200 μm, and more preferably 10 μm to 100 μm.

<Exposure process and exposure means>
The exposure can be performed, for example, by exposing the surface of the image carrier imagewise using the exposure unit.
The optical system in the exposure is roughly classified into an analog optical system and a digital optical system. The analog optical system is an optical system that projects a document directly onto an image carrier by an optical system, and the digital optical system receives image information as an electrical signal and converts it into an optical signal to convert the image information into an image carrier. Is an optical system that exposes an image.
The exposure means is not particularly limited as long as it can expose the surface of the image carrier charged by the charging means like an image to be formed, and can be appropriately selected according to the purpose. Examples include various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, a liquid crystal shutter optical system, and an LED optical system.
In the present invention, an optical back side system in which imagewise exposure is performed from the back side of the image carrier may be adopted.

<Development process and development means>
The developing step is a step of developing the electrostatic latent image using a toner or a developer to form a visible image.
The visible image can be formed, for example, by developing the electrostatic latent image using the toner or the developer, and can be performed by the developing unit.
The developing means includes at least a first developing member and a second developing member, the first developing member and the second developing member rotate in opposite directions, and the first developing member Those rotating in the opposite direction to the image carrier are used.

Here, the developing means used in the image forming apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing the configuration of the developing means 3 used in the image forming apparatus of the present invention.
As shown in FIG. 1, in a developing means 3 in which developing sleeves 2 as a plurality of developing members are arranged in parallel to face an image carrier (photosensitive body) 1, a developing sleeve containing a magnet having a magnetic pole structure is exposed to light. It is installed at the most downstream in the body rotation direction.
The developing means 3 has a first developing sleeve 2a as a first developing member and a second developing sleeve 2b as a second developing member.
In the multi-stage development method, a plurality of development sleeves are arranged in multiple stages in order to prevent a decrease in image density with respect to a solid image.
Therefore, for an image drawn with a deep electrostatic latent image such as a solid image, the toner can be sufficiently supplied to the latent image due to the effect of increasing the development time.
On the other hand, the conventional multi-stage development causes problems such as the occurrence of halos and insufficient reproducibility for line images (particularly horizontal lines). A halo is a phenomenon in which the periphery of a dark image is whitened when a dark image is developed in halftone.
A measure taken to solve these problems has been to reduce the diameter of the developing sleeve (for example, 16 mm in diameter).

On the other hand, when aiming at higher speed, the developing sleeve linear velocity is increased with the increase of the photosensitive member linear velocity, but the problem of high-speed rotation of the small-diameter developing sleeve becomes conspicuous.
The durability of the developing sleeve is deteriorated due to high-speed rotation, and halos are regenerated in terms of image quality. The total design margin is improved by proposing multi-stage development that eliminates halos and does not limit the use of small-diameter sleeves.
In general, an image reproduced by multi-stage development is determined by a contact state of a magnetic brush formed on a developing sleeve located on the most downstream side. Therefore, in this embodiment, the first developing sleeve as the first developing member and the second developing sleeve as the second developing member rotate in the opposite directions, and the first developing sleeve is the image carrier. Rotating in the opposite direction, Sm1 ≦ D ≦ Sm2 where Sm1 is the average crest distance on the first developing sleeve surface, Sm2 is the average crest distance on the second developing sleeve surface, and D is the weight average particle diameter of the carrier. It is necessary to satisfy the relationship.

In normal multi-stage development in which the first developing sleeve and the second developing sleeve rotate in the same direction as the image carrier, halos (half-tip white spots) generated in the image formed by the first developing sleeve are first detected. There is a possibility that the development sleeve 2 may be further deteriorated rather than improved.
On the other hand, in the present invention, the first developing sleeve and the second developing sleeve rotate in the opposite directions, and the first developing sleeve rotates in the opposite direction to the image carrier. A halo (half rear end white spot) occurs in the formed image, but it is milder than a halo that occurs when the developing sleeve rotates in the same direction as the image carrier. Since the second developing sleeve rotates in the same direction as the image bearing member, the effect of filling the halo (half rear end white spot) portion works. Since the second developing sleeve rotates in the same direction as the image carrier, there is a concern that halos (half-tip white spots) may occur, but the first developing sleeve has already formed an image with no white spots at the half-tip portions. So there is no worry about that. Therefore, halo does not occur at the front and rear ends of the half.

In the present invention, Sm1 is the average crest distance on the surface of the first developing sleeve as the first developing member, Sm2 is the average crest distance on the surface of the second developing sleeve as the second developing member, and When the weight average particle diameter is D, the relationship of Sm1 ≦ D ≦ Sm2 is satisfied.
As a result, when the solid image is formed, when the magnetic brush on the second developing sleeve reaches the developing area, the average crest distance Sm2 on the surface of the developing sleeve is larger than the weight average particle diameter D of the carrier. In addition, since the carrier existing at the base of the magnetic brush is fixed without slipping on the sleeve surface, a stable magnetic brush ear is formed, and excess toner at the edge that is likely to occur in the solid image formed by the first developing sleeve The scavenging force works properly to make the adhesion more uniform. If the average crest distance Sm2 on the surface of the second developing sleeve is smaller than the weight average particle diameter D of the carrier, when the magnetic brush on the second developing sleeve reaches the developing region, the carrier existing at the base of the magnetic brush is not present. Since the sleeve surface becomes slippery, the magnetic brush ears are liable to collapse due to the rubbing force between the image carrier and the developing sleeve, and the trailing edge is liable to occur.

The average crest spacing Sm1 of the first developing sleeve surface is preferably not more than the mean crest spacing Sm2 of the second developing sleeve surface and not more than the weight average particle diameter D of the carrier. As a result, the magnetic brush is optimally exchanged between the first developing sleeve and the second developing sleeve. That is, the magnetic brush formed on the surface of the first developing sleeve is easily separated from the surface of the sleeve after passing through the developing nip region. Formation is smooth.
It is preferable that the first developing member and the second developing member rotate in opposite directions, and that the first developing member further rotate in the opposite direction to the image carrier.
Accordingly, when the magnetic brush formed on the surface of the first developing sleeve passes through the developing nip region and then leaves the sleeve surface and returns into the developer, the magnetic brush is immediately pumped to the next second developing sleeve surface. Therefore, the magnetic brush formed on the surface of the second developing sleeve can be formed with a sufficient toner concentration without being insufficient.

The average crest distance Sm1 on the surface of the first developing sleeve is preferably 20 μm to 50 μm, although it depends on the weight average particle diameter of the carrier.
The average crest distance Sm2 on the surface of the second developing sleeve is preferably 20 μm to 60 μm, although it depends on the weight average particle diameter of the carrier.

Here, for example, a surface roughness meter (Surfcom 1440D, manufactured by Tokyo Seimitsu Co., Ltd., JIS B0601-1982 standard) can be used to measure the average crest distance Sm of the developing sleeve. As shown in FIG. 2, the average crest interval Sm is from the first mountain-to-valley crossing point across the center line C of the roughened cross-sectional curve D to the next mountain-to-valley crossing point. When the interval is S1, and the subsequent crossing point intervals are S2, S3,..., Sn (n indicates the total number of crossing points in the reference length), these values are arithmetically averaged. It is represented by the following formula (1). That is, qualitatively, the average peak interval Sm indicates the average interval between the peak on the surface of the developing sleeve and the adjacent peak.
Sm = (S1 + S2 + ... + Sn) / n ... Equation (1)

<< Toner >>
The weight average particle diameter of the toner is preferably 2 μm to 6 μm, and more preferably 3 μm to 5.5 μm. If the weight average particle size is less than 2 μm, halos are likely to occur, and toner may be scattered on the background part, which may easily cause background stains. If unevenness is likely to occur, the dot reproducibility becomes insufficient, the graininess of the halftone portion is also deteriorated, and a high-definition image may not be obtained.
Here, the weight average particle diameter of the toner can be measured by, for example, a toner particle size distribution measuring apparatus using a Coulter counter method.

The toner is preferably produced in an aqueous medium, and is particularly effective for obtaining a small particle size and shape in the toner.
Examples of the method for producing the toner include, but are not limited to, a suspension polymerization method, an emulsion association method, and a dissolution suspension method.

-Suspension polymerization method-
A colorant, a release agent and the like are dispersed in the oil-soluble polymerization initiator and the polymerizable monomer, and then emulsified and dispersed by an emulsification method described later in an aqueous medium containing a surfactant and other solid dispersants. Thereafter, a polymerization reaction is performed to form particles, and a surfactant is removed by washing to obtain toner particles.
Examples of the polymerizable monomer include acids such as acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride, acrylamide, methacrylamide , Diacetone acrylamide or their methylol compounds, vinyl pyridine, vinyl pyrrolidone, vinyl imidazole, ethyleneimine, dimethylaminoethyl methacrylate, etc. Can be introduced.
Further, by selecting a dispersant having an acid group or a basic group as a dispersant to be used, the dispersant can be adsorbed and left on the particle surface to introduce a functional group.

-Emulsion polymerization aggregation method-
In the emulsion polymerization aggregation method, a water-soluble polymerization initiator and a polymerizable monomer are emulsified in water using a surfactant, and a latex is synthesized by an ordinary emulsion polymerization technique. Separately, a dispersion in which a colorant, a release agent and the like are dispersed in an aqueous medium is prepared, and after mixing, the toner is aggregated to a toner size and heat-fused to obtain a toner. A functional group can be introduced on the surface of the toner particles by using a latex similar to the monomer that can be used in the suspension polymerization method.

-Polymer suspension method-
In the polymer suspension method, water alone may be used as an aqueous medium, but a solvent miscible with water may be used in combination.
Examples of the water-miscible solvent include alcohol (methanol, isopropanol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.), and the like.
In the oil phase of the toner composition, a colorant such as resin, prepolymer and pigment, a release agent, a charge control agent and the like are dissolved or dispersed in a volatile solvent.
An oil phase composed of a toner composition is dispersed in an aqueous medium in the presence of a surfactant, a solid dispersant and the like, and a prepolymer is reacted to form particles.
In order to introduce a functional group into the toner particles, a copolymer with a monomer having a functional group used in the suspension polymerization method, or a functional group of an acid group as an acid monomer in the case of a polyester resin is used. It can be obtained by using one having three or more or esterifying the terminal hydroxyl group of the obtained polyester resin with a compound having a plurality of acid groups. Further, as a dispersion stabilizer in an aqueous medium, which will be described later, an acid group-containing surfactant, polar polymer, organic or inorganic resin fine particles can be used, and an acid group can be introduced by remaining on the toner particle surface. Examples of the acid group include a carboxyl group, a sulfone group, a sulfonic acid group, and a phosphoric acid group.

  The toner to which the present invention is applied is not limited to the toner exemplified here.

  The base coloring particles of the toner contain at least a binder resin, a colorant, and a release agent, and can be obtained from a pulverization method, a suspension polymerization method, an emulsion polymerization aggregation method, or a polymer suspension method. In particular, the base colored particles of the toner according to the exemplary embodiment are close to a polymer suspension method, and include at least a polymer having a site capable of reacting with a compound having an active hydrogen group, an unmodified polyester, a colorant, and a release agent. A toner obtained by cross-linking and / or elongation reaction of a toner material solution, each of which is dissolved or dispersed in an organic solvent, in an aqueous medium is preferable.

The polymer having a site capable of reacting with the compound having an active hydrogen group is preferably a polyester prepolymer having a site capable of reacting with a compound having an active hydrogen group. This polyester prepolymer undergoes crosslinking and / or elongation reaction in an aqueous medium and is contained in the toner as a modified polyester (i).
The modified polyester (i) refers to a state in which a bonding group other than an ester bond is present in the polyester resin, and resin components having different configurations are bonded to the polyester resin by a covalent bond, an ionic bond, or the like. Specifically, the polyester terminal is modified by introducing a functional group such as a carboxylic acid group or an isocyanate group that reacts with a hydroxyl group into the polyester terminal and further reacting with a compound having an active hydrogen group.

[Toner Production Method (1) to (5)]
(1) A toner material solution is prepared by dissolving or dispersing at least a polymer having a site capable of reacting with a compound having an active hydrogen group, an unmodified polyester, a colorant, and a release agent in an organic solvent. As the polymer having a site capable of reacting with a compound having an active hydrogen group, a polyester prepolymer having a site capable of reacting with a compound having an active hydrogen group is preferred, for example, a polyester prepolymer (A) having an isocyanate group. Can be mentioned.
As the polyester prepolymer (A) having an isocyanate group, a polycondensate of a polyhydric alcohol (PO) and a polyvalent carboxylic acid (PC) and a polyester having an active hydrogen group, and a polyvalent isocyanate compound (PIC) And those reacted with. Examples of active hydrogen groups possessed by such polyesters include hydroxyl groups (alcoholic hydroxyl groups and phenolic hydroxyl groups), amino groups, carboxyl groups, mercapto groups, and the like. Among these, alcoholic hydroxyl groups are particularly preferable.

Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). Among these, a dihydric alcohol (DIO) alone or a mixture of a dihydric alcohol (DIO) and a small amount of a trihydric or higher polyhydric alcohol (TO) is preferable.
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 oxides of the alicyclic diols (ethylene oxide, propylene oxide, butylene oxide, etc.) Addendum; alkylene oxide of the bisphenols (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. As trihydric or higher polyhydric alcohol (TO), trihydric or higher polyhydric aliphatic alcohol (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent 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) 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 of the polyhydric alcohol (PO) and the polyhydric carboxylic acid (PC) is usually 2/1 to 1/1 as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. The ratio is preferably 1.5 / 1 to 1/1, and more preferably 1.3 / 1 to 1.02 / 1.
As the polyhydric alcohol compound (PO) and polyvalent carboxylic acid (PC), in addition to those exemplified above, other substances may be used as long as they can form a polyester having an active hydrogen group by polycondensation. It is also possible to do.

  Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane). Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; Those blocked with oxime, caprolactam, etc .; these two or more types may be used in combination.

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. Is 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. More preferably, the content is 20% by mass to 20% by mass. 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 isocyanate groups is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to average on average. 2.5 pieces. 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.
Further, the toner according to the present embodiment is not limited to the above-described modified polyester (i) (polyester prepolymer (A)) alone, but also the modified polyester (i) and the unmodified polyester (ii) as a binder resin component. It can also be contained. By using unmodified polyester (ii) in combination, the low-temperature fixability and the gloss when used in a full-color apparatus are improved, which is preferable to single use.

-Unmodified polyester-
Examples of the unmodified polyester (ii) include polycondensates of a polyhydric alcohol (PO) and a polyvalent carboxylic acid (PC) similar to the polyester component of the modified polyester (i). Same as (i). The unmodified polyester (ii) may be modified with a chemical bond other than a urea bond, and may be modified with, for example, a urethane bond. It is preferable that the modified polyester (i) and the unmodified polyester (ii) are at least partially compatible in terms of low-temperature fixability and hot offset resistance. Therefore, the polyester component of the modified polyester (i) and the unmodified polyester (ii) preferably have similar compositions. When the unmodified polyester (ii) is contained, the mass ratio of (i) and (ii) is preferably 5/95 to 80/20, more preferably 5/95 to 30/70, and 5/95 to 25 /. 75 is more preferable, and 7/93 to 20/80 is particularly preferable. When the mass ratio of the modified polyester (i) is less than 5% by mass, the hot offset resistance may be deteriorated, and it may be disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

The peak molecular weight of the unmodified polyester (ii) is preferably 1,000 to 10,000, more preferably 2,000 to 8,000, and still more preferably 2,000 to 5,000. When the peak molecular weight is less than 1,000, the heat resistant storage stability may be deteriorated, and when it exceeds 10,000, the low-temperature fixability may be deteriorated.
The hydroxyl value of the unmodified polyester (ii) is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g to 120 mgKOH / g, and still more preferably 20 mgKOH / g to 80 mgKOH / g. If the hydroxyl value is less than 5 mgKOH / g, it may be disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.
The acid value of the unmodified polyester (ii) is preferably 1 mgKOH / g to 5 mgKOH / g, more preferably 2 mgKOH / g to 4 mgKOH / g. Since a high acid value wax is used for the wax, the binder resin is easily matched with the toner used for the two-component developer because the low acid value binder resin leads to charging and high volume resistance.

  The glass transition temperature Tg of the binder resin is preferably 35 ° C to 70 ° C, more preferably 55 ° C to 65 ° C. When the glass transition temperature Tg is less than 35 ° C., the heat-resistant storage stability of the toner is deteriorated, and when it exceeds 70 ° C., the low-temperature fixability becomes insufficient. Since urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the toner tends to have good heat-resistant storage stability even at a low glass transition temperature Tg, 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 Dan, 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 Carmine 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 blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, lithopone and mixtures thereof can be used.
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 used in the toner 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 masterbatch or the masterbatch, in addition to the modified and unmodified polyester resins mentioned above, styrene such as polystyrene, poly p-chlorostyrene, and polyvinyltoluene, and polymers of substituted products thereof; Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer Styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α- Chloromethyl methacrylate copolymer, Len-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid Styrene copolymers such as acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, poly Acrylic acid resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like can be used alone or in combination. .
This master batch can be obtained by mixing and kneading a master batch resin and a colorant under a high shear force to obtain a master batch. In this case, an organic solvent can be used in order to enhance the interaction between the colorant and the resin. In addition, a so-called flushing method called watering paste containing water of colorant is mixed and kneaded together with resin and organic solvent, and the colorant is transferred to the resin side to remove moisture and organic solvent components. Since it can be used as it is, it does not need to be dried and is preferably used. For mixing and kneading, a high shear dispersion device such as a three-roll mill is preferably used.

-Release agent-
The toner may contain a wax as a release agent together with a binder resin and a colorant. The wax is not particularly limited and known ones can be used. Examples thereof include polyolefin wax (polyethylene wax, polypropylene wax, etc.); long chain hydrocarbon (paraffin wax, sasol wax, etc.); carbonyl group-containing wax, etc. It is done.
Of these, carbonyl group-containing waxes are preferred. Examples of the carbonyl group-containing wax include polyalkanoic acid esters (carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18. -Octadecanediol distearate, etc.); polyalkanol esters (tristearyl trimellitic acid, distearyl maleate, etc.); polyalkanoic acid amides (ethylene diamine dibehenyl amide, etc.); polyalkylamides (trimellitic acid tristearyl amide, etc.) And dialkyl ketones (such as distearyl ketone). Among these carbonyl group-containing waxes, polyalkanoic acid esters are preferred.

  The melting point of the wax is preferably 40 ° C to 160 ° C, more preferably 50 ° C to 120 ° C, and still more preferably 60 ° C to 90 ° C. If the melting point is less than 40 ° C., the heat-resistant storage stability may be adversely affected, and waxes exceeding 160 ° C. tend to cause cold offset when fixing at low temperatures. Further, the melt viscosity of the wax is preferably 5 cps to 1,000 cps, more preferably 10 cps to 100 cps, as a measured value at a temperature 20 ° C. higher than the melting point. Waxes exceeding 1000 cps have poor effects for improving hot offset resistance and low-temperature fixability. The content of the wax in the toner is preferably 0 to 40% by mass, and more preferably 3% to 30% by mass.

-Charge control agent-
The toner may contain a charge control agent as necessary. All known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified). 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, Nitronine dye Bontron 03, quaternary ammonium salt quotient Bontron P-51, metal-containing azo dye Bontron S-34, oxynaphthoic acid metal complex E-82, salicylic acid metal complex E -84, phenolic condensate E-89 (above, trade name, manufactured by Orient Chemical Industries), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, trade name, 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 (above, trade name, manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (trade name, manufactured by Nippon Carlit), copper lid Cyanine, perylene, quinacridone, azo pigments, sulfonate group, carboxyl group, and polymer compounds having a functional group such as a quaternary ammonium salt.
The amount of the charge control agent used is determined by the toner production method including the type of 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. If the amount used exceeds 10 parts by mass, the chargeability of the toner is too high, the effect of the main charge control agent is reduced, the electrostatic attraction force with the developing roller is increased, the flowability of the developer is reduced, This causes a decrease in image density. These charge control agents can be dissolved and dispersed after being melt-kneaded with a masterbatch and resin, or of course, may be added when directly dissolving or dispersing in an organic solvent, or may be fixed on the toner surface after preparation of toner particles. May be.

-External additive-
As an external additive for assisting the fluidity, developability and chargeability of the obtained colored particles, inorganic fine particles, hydrophobized inorganic fine particles and the like can be used. Any of them can be used as long as the conditions are satisfied. For example, silica fine particles, hydrophobic silica, fatty acid metal salts (such as zinc stearate and aluminum stearate), metal oxides (such as titania, alumina, tin oxide, and antimony oxide) may be contained. In addition, polymer fine particles, such as polystyrene obtained by soap-free emulsion polymerization, suspension polymerization, and dispersion polymerization, methacrylate esters, acrylate copolymers, polycondensation systems such as silicone, benzoguanamine, and nylon, thermosetting Examples thereof include polymer particles made of a resin. Particularly suitable external additives include hydrophobized silica, titania, titanium oxide, and alumina fine particles.
As silica fine particles, HDK H2000, HDK H2000 / 4, HDK H2050EP, HVK21, HDK H1303 (above, trade name, manufactured by Hoechst) and R972, R974, RX200, RY200, R202, R805, R812 (above, trade name, Nippon Aerosil Co., Ltd.). Further, as titania fine particles, P-25 (trade name, manufactured by Nippon Aerosil Co., Ltd.), STT-30, STT-65C-S (above, trade name, manufactured by Titanium Industry Co., Ltd.), TAF-140 (trade name, Fuji Titanium). Manufactured by Kogyo Co., Ltd.), MT-150W, MT-500B, MT-600B, MT-150A (above, trade name, manufactured by TEIKA). In particular, as hydrophobized titanium oxide fine particles, T-805 (trade name, manufactured by Nippon Aerosil Co., Ltd.), STT-30A, STT-65S-S (above, trade name, manufactured by Titanium Industry Co., Ltd.), TAF-500T, There are TAF-1500T (the trade name, manufactured by Fuji Titanium Industry Co., Ltd.), MT-100S, MT-100T (the trade name, manufactured by Teica), IT-S (made by Ishihara Sangyo Co., Ltd.), and the like.
In order to obtain hydrophobized inorganic fine particles, silica fine particles, titania fine particles, and alumina fine particles, hydrophilic fine particles are treated with a silane coupling agent such as methyltrimethoxysilane, methyltriethoxysilane, or octyltrimethoxysilane. Can be obtained. In addition, silicone oil-treated inorganic fine particles obtained by treating the silicone oil with heat if necessary to treat the inorganic fine particles are also suitable.

  The silicone oil is not particularly limited and may be appropriately selected depending on the intended purpose. For example, dimethyl silicone oil, methylphenyl silicone oil, chlorophenyl silicone oil, methyl hydrogen silicone oil, alkyl-modified silicone oil, fluorine-modified Silicone oil, polyether modified silicone oil, alcohol modified silicone oil, amino modified silicone oil, epoxy modified silicone oil, epoxy / polyether modified silicone oil, phenol modified silicone oil, carboxyl modified silicone oil, mercapto modified silicone oil, acrylic, methacrylic Modified silicone oil, α-methylstyrene modified silicone oil and the like can be used.

  The organic solvent used for preparing the toner material liquid is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are preferred. 300 mass parts or less are preferable with respect to 100 mass parts of polyester prepolymers, and, as for the usage-amount of an 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 contains an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be a thing. The amount of the aqueous medium used relative to 100 parts by mass of the toner material liquid is preferably 50 parts by mass to 2,000 parts by mass, and more preferably 100 parts by mass to 1,000 parts by mass. When the amount used is less than 50 parts by mass, the toner material liquid is not well dispersed and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 2,000 parts by mass, it is not economical.

  Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added. Examples of the surfactant include anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates and phosphates, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, and amine salt types such as imidazoline. And quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, benzethonium chloride, fatty acid amide derivatives, Amphoteric surfactants such as dihydric alcohol derivatives such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine Surface active agents.

Further, by using a surfactant having a fluoroalkyl group, the effect can be increased in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms or metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C16 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C16-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.
Moreover, as anionic surfactant, Surflon S-111, S-112, S-113 (above, a brand name, Asahi Glass Co., Ltd. product), Florard FC-93, FC-95, FC-98, FC-129 ( Above, trade name, manufactured by Sumitomo 3M), Unidyne DS-101, DS-102 (above, trade name, manufactured by Daikin Industries), MegaFuck F-110, F-120, F-113, F-191, F -812, F-833 (above, trade name, manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204, (above, trade name) , Manufactured by Tochem Products Co., Ltd.), Fantent F-100, F150 (above, trade name, manufactured by Neos), and the like.

  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 and the like. As cationic surfactants, Surflon S-121 (trade name, manufactured by Asahi Glass Co., Ltd.), Florard FC-135 (trade name, manufactured by Sumitomo 3M), Unidyne DS-202 (trade name, manufactured by Daikin Industries), Mega Fax F-150, F-824 (above, trade name, manufactured by Dainippon Ink & Chemicals, Inc.), Xtop EF-132 (trade name, manufactured by Tochem Products), Footgent F-300 (trade name, Neos) Manufactured).

The resin fine particles are not particularly limited, and any resin can be used as long as it can form an aqueous dispersion, and may be a thermoplastic resin or a thermosetting resin. Examples thereof include vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicon resins, phenol resins, melamine resins, urea resins, aniline resins, ionomer resins, and polycarbonate resins. As the resin, two or more of the above resins may be used in combination.
Among these, a vinyl resin, a polyurethane resin, an epoxy resin, a polyester resin, and a combination thereof are preferable because an aqueous dispersion of fine spherical resin particles can be easily obtained. For example, vinyl resins are polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene- (meth) acrylic acid ester copolymers, styrene-butadiene copolymers, (meth) acrylic acid-acrylic acid esters. Examples thereof include resins such as a polymer, a styrene-acrylonitrile copolymer, a styrene-maleic anhydride copolymer, and a styrene- (meth) acrylic acid copolymer. The average particle size of the resin fine particles is preferably 5 nm to 300 nm, and more preferably 20 nm to 200 nm. 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 polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomers containing hydroxyl groups Bodies such as acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxy Propyl, acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Luric acid esters, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc., or compounds containing vinyl alcohol and a carboxyl group Esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl Nitrogen compounds such as imidazole and ethyleneimine, or homopolymers or copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, polyoxypropylene , Polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene Polyoxyethylenes such as nonylphenyl ester, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

  The dispersion method is not particularly limited and may be appropriately selected depending on the intended purpose. For example, known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. . Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 μm to 20 μm. When a high-speed shearing disperser is used, the number of rotations is not particularly limited, but is preferably 1,000 to 30,000 rpm, and more preferably 5,000 to 20,000 rpm. The dispersion time is not particularly limited, but is preferably 0.1 minutes to 5 minutes in the case of a batch method. The temperature during dispersion is preferably 0 ° C to 150 ° C (under pressure), more preferably 40 ° C to 98 ° C.

(3) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group. This reaction involves at least one of a molecular chain crosslinking reaction and / or an elongation reaction. The polyester prepolymer (A) undergoes a crosslinking reaction and / or elongation reaction in an aqueous medium and is contained in the toner as a modified polyester (i).
The reaction time is selected depending on the reactivity between the isocyanate group structure of the polyester prepolymer (A) and the amines (B), but is preferably 10 minutes to 40 hours, more 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.

The weight average molecular weight of the modified polyester (i) is preferably 10,000 or more, more preferably 20,000 to 10,000,000, and still more preferably 30,000 to 1,000,000. The peak molecular weight at this time is preferably 1,000 to 10,000. When the peak molecular weight is less than 1,000, the elongation reaction hardly occurs, and the elasticity of the toner is small. As a result, the hot offset resistance may be deteriorated. And manufacturing problems may be increased in pulverization.
The number average molecular weight of the modified polyester (i) is not particularly limited when the above-described unmodified polyester (ii) is used, and is a number average molecular weight that can be easily obtained as the weight average molecular weight. Good. In the case of the modified polyester (i) alone, the number average molecular weight is preferably 20,000 or less, more preferably 1,000 to 10,000, and still more preferably 2,000 to 8,000. When the number average molecular weight exceeds 20,000, low temperature fixability and glossiness when used in a full color apparatus may be deteriorated.

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

Examples of the amines (B) to be reacted with the polyester prepolymer (A) include a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), and an amino mercaptan (B4). , Amino acid (B5), and amino acids B1 to B5 blocked (B6).
Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-). Dimethyl dicyclohexyl methane, diamine cyclohexane, isophorone diamine, etc.); aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like.
Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of the amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of the 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 mass ratio of the amines (B) is equivalent to the equivalent ratio [NCO] / [NCO] of the isocyanate group [NCO] in the polyester prepolymer (A) having an isocyanate group and the amino group [NHX] in the amine (B). NHX] is preferably 1/2 to 2/1, more preferably 1.5 / 1 to 1 / 1.5, and still more preferably 1.2 / 1 to 1 / 1.2. When the equivalent ratio [NCO] / [NHX] is more than 2 and 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 mol%, the hot offset resistance may be deteriorated.

(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. . When a dispersion stabilizer that is soluble in an acid or alkali such as calcium phosphate is used, the calcium phosphate is dissolved from the toner base particles by a method such as dissolving the calcium phosphate 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 the inorganic fine particles are performed by a known method using a mixer or the like.
Thereby, a toner having a small particle size and a sharp particle size distribution can be easily obtained.
Furthermore, by applying strong agitation in the process of removing the organic solvent, the shape between the spherical shape and the rugby ball shape can be controlled, and the surface morphology is also controlled between the smooth shape and the umeboshi shape. be able to.

<< Developer >>
The toner is used as a developer, and a two-component developer including a carrier and a toner is used as the developer.

There is no restriction | limiting in particular as said carrier, Although it can select suitably according to the objective, What has a core material and the resin layer which coat | covers this core material is preferable.
There is no restriction | limiting in particular as a material of the said core material, It can select suitably from well-known things, For example, a manganese-strontium (Mn-Sr) type material of 50 emu / g-90 emu / g, manganese-magnesium ( A Mn—Mg) -based material is preferable, and from the viewpoint of securing image density, a highly magnetized material such as iron powder (100 emu / g or more), magnetite (75 emu / g to 120 emu / g) is preferable. In addition, the copper-zinc (Cu—Zn) system (30 emu / g to 80 emu / g) is advantageous in that it can weaken the contact with the electrostatic latent image bearing member in which the toner is in a spiked state and is advantageous for high image quality. A weakly magnetized material such as These may be used alone or in combination of two or more.

The material of the resin layer is not particularly limited and can be appropriately selected from known resins according to the purpose. For example, amino resins, polyvinyl resins, polystyrene resins, halogenated olefin resins, Polyester resin, polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, copolymer of vinylidene fluoride and acrylic monomer, vinylidene fluoride And fluorinated terpolymers (triple fluorinated (multiple) copolymers) such as terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, silicone resins, etc. It is done. These may be used individually by 1 type and may use 2 or more types together. Among these, a silicone resin is particularly preferable.
The silicone resin is not particularly limited and can be appropriately selected according to the purpose from generally known silicone resins. For example, a straight silicone resin consisting only of an organosilosan bond; an alkyd resin; Examples thereof include polyester resins, epoxy resins, acrylic resins, silicone resins modified with urethane resins, and the like.
Commercially available products can be used as the silicone resin. Examples of straight silicone resins include KR271, KR255, and KR152 manufactured by Shin-Etsu Chemical Co., Ltd .; SR2400, SR2406, and SR2410 manufactured by Toray Dow Corning Silicone Co., Ltd. Etc.
Commercially available products can be used as the modified silicone resin. For example, KR206 (alkyd modified), KR5208 (acryl modified), ES1001N (epoxy modified), KR305 (urethane modified) manufactured by Shin-Etsu Chemical Co., Ltd .; SR2115 (epoxy-modified), SR2110 (alkyd-modified) manufactured by Dow Corning Silicone Co., Ltd., and the like.
In addition, although a silicone resin can be used alone, it is also possible to simultaneously use a component that undergoes a crosslinking reaction, a charge amount adjusting component, and the like.

The resin layer may contain conductive powder or the like as necessary. Examples of the conductive powder include metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide. The average particle diameter of these conductive powders is preferably 1 μm or less. When the average particle diameter exceeds 1 μm, it may be difficult to control electric resistance.
For example, the resin layer is prepared by dissolving the silicone resin or the like in a solvent to prepare a coating solution, and then uniformly coating the coating solution on the surface of the core material by a known coating method, drying, and baking. It can be formed by doing. Examples of the application method include an immersion method, a spray method, and a brush coating method.
There is no restriction | limiting in particular as said solvent, Although it can select suitably according to the objective, For example, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cellosolve, butyl acetate, etc. are mentioned.
The baking is not particularly limited, and may be an external heating method or an internal heating method. For example, a stationary electric furnace, a fluid electric furnace, a rotary electric furnace, a burner furnace, etc. The method of using, the method of using a microwave, etc. are mentioned.
The amount of the resin layer in the carrier is preferably 0.01% by mass to 5.0% by mass. When the amount is less than 0.01% by mass, the uniform resin layer may not be formed on the surface of the core material. When the amount exceeds 5.0% by mass, the resin layer becomes thick. In some cases, granulation of carriers occurs, and uniform carrier particles may not be obtained.

The carrier preferably has a weight average particle diameter D of 15 μm to 45 μm.
Here, as the weight average particle diameter D of the carrier, for example, a Microtrac particle size analyzer model HRA9320-X100 (manufactured by Honeywell) can be used. The measurement conditions are as follows.
[1] Particle size range: 8 to 100 μm
[2] Channel length (channel width): 2 μm
[3] Number of channels: 46
[4] Refractive index: 2.42

  The mixing ratio of the toner and the carrier in the developer is not particularly limited and may be appropriately selected according to the purpose. The amount is preferably 1 part by mass to 10 parts by mass of the toner with respect to 100 parts by mass of the carrier.

-Transfer process and transfer means-
The transfer step is a step of transferring the visible image onto a recording medium. After the primary transfer of the visible image onto the intermediate transfer member using an intermediate transfer member, the visible image is transferred onto the recording medium. A primary transfer step of forming a composite transfer image by transferring a visible image onto an intermediate transfer body using two or more colors, preferably full color toner as the toner, and a composite transfer image; A mode including a secondary transfer step of transferring the transfer image onto the recording medium is more preferable.
The transfer can be performed, for example, by charging the image carrier (photosensitive member) with the transfer charger using the visible image, and can be performed by the transfer unit. The transfer means includes 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. Embodiments are preferred.
The intermediate transfer member is not particularly limited and may be appropriately selected from known transfer members according to the purpose. For example, a transfer belt and the like are preferable.

The transfer means (the primary transfer means and the secondary transfer means) includes at least a transfer device that peels and charges the visible image formed on the image carrier (photoconductor) to the recording medium side. It is preferable to have. There may be one transfer means or two or more transfer means.
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 is not particularly limited and can be appropriately selected from known recording media (recording paper).

The fixing step is a step of fixing the visible image transferred to the recording medium using a fixing unit, and may be performed each time the toner of each color is transferred to the recording medium, or for the toner of each color. You may perform this simultaneously in the state which laminated | stacked this.
The fixing unit is not particularly limited and may be appropriately selected depending on the intended purpose, but a known heating and pressing unit is preferable. 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 pressing means is preferably 80 ° C to 200 ° C.
In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing step and the fixing unit depending on the purpose.

The neutralization step is a step of performing neutralization by applying a neutralization bias to the image carrier, and can be suitably performed by a neutralization unit.
The neutralization means is not particularly limited and may be appropriately selected from known neutralizers as long as it can apply a neutralization bias to the image carrier. It is done.

The cleaning step is a step of removing the toner remaining on the image carrier and can be suitably performed by a cleaning unit.
The cleaning means is not particularly limited, and may be selected from known cleaners as long as it can remove the electrophotographic toner remaining on the image carrier. For example, a magnetic brush cleaner, Suitable examples include electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

The recycling step is a step of recycling the toner removed by the cleaning step to the developing unit, and can be suitably performed by the recycling unit.
There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.

The control step is a step of controlling each of the steps, and can be suitably performed by a control unit.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as sequencers and computers.

Here, the image forming apparatus and the image forming method of the present invention will be described in detail with reference to the drawings.
FIG. 3 is a schematic view showing an example of the image forming apparatus of the present invention.
The image carrier 10 rotates in the direction of the arrow in FIG. 3, and around the image carrier 10, there are a charging unit 11, an exposure unit 12, a developing unit 13, a transfer unit 16, a cleaning unit 17, a neutralizing unit 18, and the like. Is placed. The cleaning unit 17 and the charge removal unit 18 may be omitted.

  The operation of the image forming apparatus is basically as follows. The charging unit 11 charges the surface of the image carrier 10 almost uniformly. Subsequently, image light writing corresponding to the input signal is performed by the exposure unit 12 to form an electrostatic latent image. Next, the electrostatic latent image is developed by the developing means 13 to form a toner image on the surface of the image carrier. The formed toner image is transferred by the transfer unit 16 to the recording medium 15 sent to the transfer site by the conveying roller 14. This toner image is fixed on the recording medium by a fixing device (not shown). Part of the toner that has not been transferred to the recording medium is cleaned by the cleaning means 17. Next, the charge remaining on the image carrier 10 is neutralized by the neutralizing means 18 and proceeds to the next cycle.

As shown in FIG. 3, the image carrier (photoconductor) 10 has a drum shape, but may be a sheet or an endless belt. For the charging means 11 and the transfer means 16, in addition to corotron, scorotron, solid state charger (solid state charger), roller-like charging means or brush-like charging means are used, and all known means can be used. It is.
On the other hand, the light sources such as the exposure means 12 and the charge eliminating means 18 are luminescent materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL). General can be used. Among these, a semiconductor laser (LD) and a light emitting diode (LED) are mainly used.
Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.
The light source or the like provides the image carrier 10 with light by providing a transfer process, a static elimination process, a cleaning process, or a pre-exposure process using light irradiation. However, the exposure of the image carrier 10 in the charge removal step has a large influence of fatigue on the image carrier 10 and may cause a decrease in charge and an increase in residual potential.
Therefore, there are cases where it is possible to eliminate static electricity by applying a reverse bias in the charging process or cleaning process instead of static elimination by exposure, which may be effective in terms of enhancing the durability of the image carrier.

When the image carrier 10 is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the image carrier. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.
A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.
Among contaminants adhering to the surface of the image carrier, discharge substances generated by charging and external additives contained in the toner are easy to pick up the influence of humidity and cause abnormal images. Paper dust is one of the causative substances, and when they adhere to the image carrier, not only abnormal images are likely to occur, but also wear resistance is reduced or uneven wear is caused. The tendency to do is seen. Therefore, it is more preferable from the viewpoint of high image quality that the image carrier and the paper are not in direct contact for the above reasons.

The toner developed on the image carrier 10 by the developing means 13 is transferred to the recording medium 15, but not all is transferred, and toner remaining on the image carrier 10 is also generated. Such toner is removed from the image carrier 10 by the cleaning means 17.
As this cleaning means 17, a known one such as a cleaning blade or a cleaning brush is used. Moreover, both may be used together.

  In the present invention, since high photosensitivity and high stability are realized, it can be applied to a small-diameter image carrier. As an image forming apparatus or a system thereof in which the small-diameter image carrier is more effectively used, each developing unit corresponding to a plurality of color toners includes a plurality of corresponding image carriers, thereby performing parallel processing. It is very effectively used in a so-called tandem image forming apparatus. The tandem image forming apparatus includes at least four color toners of yellow (C), magenta (M), cyan (C), and black (K) required for full-color printing and a developing unit that holds them. Further, by providing at least four image carriers corresponding to them, full-color printing can be performed at a very high speed as compared with a conventional image forming apparatus capable of full-color printing.

FIG. 4 is a schematic view for explaining the tandem-type full-color electrophotographic apparatus of the present invention.
In FIG. 4, an image carrier (10C (cyan)), an image carrier (10M (magenta)), an image carrier (10Y (yellow)), and an image carrier (10K (black)) are drum-shaped images. The image carrier (10C, 10M, 10Y, 10K) rotates in the direction of the arrow in the drawing, and charging means (11C, 11M, 11Y, 11K) and development at least in the order of rotation therearound. Means (13C, 13M, 13Y, 13K) and cleaning means (17C, 17M, 17Y, 17K) are arranged.
From the back side of the image carrier 10 between the charging means (11C, 11M, 11Y, 11K) and the developing means (13C, 13M, 13Y, 13K), laser light (12C, 12M) from an exposure means (not shown). , 12Y, 12K), and electrostatic latent images are formed on the image carriers (10C, 10M, 10Y, 10K).
Then, four image forming elements (20C, 20M, 20Y, 20K) centering on such image carriers (10C, 10M, 10Y, 10K) are arranged along the transfer conveyance belt 19 which is a transfer material conveyance means. It is juxtaposed.
The transfer conveyance belt 19 carries an image between the developing means (13C, 13M, 13Y, 13K) of each image forming unit (20C, 20M, 20Y, 20K) and the cleaning means (17C, 17M, 17Y, 17K). A transfer means (16C, 16M, 16Y) for applying a transfer bias to a surface (back surface) which is in contact with the body (10C, 10M, 10Y, 10K) and contacts the back side of the transfer carrier belt 19 on the image carrier 10 side. , 16K). Each image forming element (20C, 20M, 20Y, 20K) is different in the color of the toner inside the developing device, and the others are the same in configuration.

In the color electrophotographic image forming apparatus having the configuration shown in FIG. 4, the image forming operation is performed as follows. First, in each of the image forming elements (20C, 20M, 20Y, 20K), the charging means (11C, 11M, 11Y) in which the image carrier (10C, 10M, 10Y, 10K) rotates along with the image carrier 10 in the peripheral direction. , 11K), and then corresponding to the image of each color to be created by laser light (12C, 12M, 12Y, 12K) by an exposure unit (not shown) arranged outside the image carrier (10). An electrostatic latent image is formed.
Next, the latent image is developed by developing means (13C, 13M, 13Y, 13K) to form a toner image. Developing means (13C, 13M, 13Y, 13K) are developing means for developing with toners of C (cyan), M (magenta), Y (yellow), and K (black), respectively, and four image carriers (10C). , 10M, 10Y, and 10K), the toner images of the respective colors are superimposed on the transfer conveyance belt 19.

  The recording medium 15 is fed from the tray by a paper feed roller 21, temporarily stopped by a pair of registration rollers 22, and sent to the transfer unit 23 in synchronism with the image formation on the image carrier. The toner image held on the transfer conveyance belt 19 is transferred onto the recording medium 15 by an electric field formed from the potential difference between the transfer bias applied to the transfer means 23 and the transfer conveyance belt 19. The toner image transferred onto the recording medium is conveyed, the toner is fixed on the recording medium by the fixing unit 24, and is discharged to a paper discharge unit (not shown). Further, residual toner remaining on each image carrier (10C, 10M, 10Y, 10K) without being transferred by the transfer unit is collected by cleaning means (17C, 17M, 17Y, 17K) provided in each unit. Is done.

The intermediate transfer method as shown in FIG. 4 is particularly effective for an image forming apparatus capable of full-color printing. By forming a plurality of toner images once on an intermediate transfer body and transferring them to paper at once, It is easy to control the color shift and is effective for high image quality.
The intermediate transfer member includes various materials or shapes such as a drum shape and a belt shape. In the present invention, any conventionally known intermediate transfer member can be used. Effective and useful for durability or high image quality.
In the example of FIG. 4, the image forming elements are arranged in the order of C (cyan), M (magenta), Y (yellow), and K (black) from the upstream side to the downstream side in the recording medium conveyance direction. However, it is not limited to this order, and the color order is arbitrarily set. Further, when a black-only document is created, it is particularly effective to use the present invention to provide a mechanism that stops the image forming elements (20C, 20M, 20Y) other than black.
The image forming apparatus using the tandem method can transfer a plurality of toner images at a time, so that high-speed full-color printing is realized.
The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge.

(Process cartridge)
The process cartridge of the present invention includes at least an image carrier and a developing unit that develops an electrostatic latent image formed on the image carrier using a developer containing toner and a carrier to form a visible image. And other means as necessary.
The process cartridge can be detachably provided in various electrophotographic image forming apparatuses, facsimiles, and printers, and it is particularly preferable that the process cartridge is detachably provided in the image forming apparatus of the present invention.

In the process cartridge, the developing means includes at least a first developing member and a second developing member, and the first developing member and the second developing member rotate in opposite directions, One developing member rotates in a direction opposite to the image carrier, the average crest distance on the surface of the first developing member is Sm1, the average crest distance on the surface of the second developing member is Sm2, and the developer carrier When the weight average particle diameter is D, it is necessary to satisfy the following formula: Sm1 ≦ D ≦ Sm2.
As the image carrier and the other means, those similar to the image forming apparatus can be used.

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, the weight average particle diameter and particle size distribution of the toner, the weight average particle diameter of the carrier, and the thickness of the coating layer of the carrier were measured as follows.

<Measurement of weight average particle size and particle size distribution of toner>
Measurement was performed as follows using a Coulter Counter TA-II (manufactured by Coulter, Inc.) as a toner particle size distribution measuring apparatus by the Coulter Counter method.
First, 0.1 ml to 5 ml of a surfactant (alkylbenzene sulfonate) was added as a dispersant to 100 ml to 150 ml of the electrolytic aqueous solution. Here, the electrolytic solution was prepared by preparing a 1% by mass NaCl aqueous solution using primary sodium chloride, and was used by ISOTON-II (manufactured by Coulter). Further, 2 mg to 20 mg of a measurement sample was added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for 1 minute to 3 minutes, and the measurement device is used to measure the mass and number of toner particles or toner using a 100 μm aperture as an aperture. Weight distribution and number distribution were calculated. From the obtained distribution, the weight average particle diameter (D ₄ ), number average particle diameter (Dn), and D ₄ / Dn of the toner were determined.
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; 13 channels of 32.00 μm or more and less than 40.30 μm were used, and particles having a particle size of 2.00 μm or more and less than 40.30 μm were targeted.

<Measurement of weight average particle diameter of carrier>
The weight average particle size of the carrier is calculated based on the particle size distribution (relationship between the number frequency and the particle size) of the particles measured on the basis of the number, and is expressed by the following formula 1.
<Formula 1>
Dw = {1 / Σ (nD ³ )} × {Σ (nD ⁴ )}
In Equation 1, D represents the representative particle size (μm) of particles present in each channel, and n represents the total number of particles present in each channel. The channel indicates a length for equally dividing the particle size range in the particle size distribution diagram, and 2 μm was adopted. In addition, as the representative particle size of the particles present in each channel, the lower limit value of the particle size of the particles stored in each channel was adopted.
As a particle size analyzer for measuring the particle size distribution, for example, a Microtrac particle size analyzer model HRA9320-X100 (manufactured by Honeywell) can be used, and the measurement conditions are as follows.
-Particle size range: 8-100 μm
-Channel length (channel width): 2 μm
-Number of channels: 46
-Refractive index: 2.42

<Measurement of thickness of carrier coating layer>
The thickness of the coating layer was determined by observing the cross section of the carrier with a transmission electron microscope (TEM), observing the coating layer covering the carrier surface, and taking the average thickness as the thickness of the coating layer.

(Production Example 1)
<Preparation of Toner A>
-Synthesis of organic fine particle emulsion-
In a reaction vessel in which a stirrer and a thermometer are set, 683 parts by mass of water, 11 parts by mass of sodium salt of ethylene oxide methacrylate adduct sulfate (Eleminol RS-30, manufactured by Sanyo Chemical Industries Ltd.), 166 methacrylic acid When a mass part, 110 mass parts of butyl acrylate, and 1 mass part of ammonium persulfate were prepared and stirred for 30 minutes at 3,800 rpm, a white emulsion was obtained. The system was heated to raise the system temperature to 75 ° C. and reacted for 4 hours. Further, 30 parts by mass of a 1% by mass aqueous ammonium persulfate solution was added, and the mixture was aged at 75 ° C. for 6 hours. A dispersion [fine particle dispersion 1] was obtained. The volume average particle diameter of [fine particle dispersion 1] measured with a particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.) was 110 nm. A portion of [Fine Particle Dispersion 1] was dried to isolate the resin component.
The glass transition temperature (Tg) of the resin was 58 ° C., and the weight average molecular weight was 130,000.

-Preparation of aqueous phase-
990 parts by weight of water, 83 parts by weight of [Fine Particle Dispersion 1], 37 parts by weight of an aqueous solution of 48.3% by weight of sodium dodecyl diphenyl ether disulfonate (Eleminol MON-7, manufactured by Sanyo Chemical Industries, Ltd.), and 90 parts by weight of ethyl acetate Were mixed and stirred to obtain a milky white liquid. This is designated as [Aqueous Phase 1].

-Preparation of aqueous solution of fluorinated activator-
N, N, N, -trimethyl- [3- (4-perfluorononenyloxybenzamido) propyl] ammonium iodide (product name: Footage 310, manufactured by Neos) 10 parts by mass and 297 parts by mass of methanol in a container The mixture was heated to 50 ° C. and stirred until it became transparent. The obtained fluorine-based activator methanol solution was dropped into 693 parts by mass of stirring ion-exchanged water, and stirred at 50 ° C. for 30 minutes after completion of the dropping to obtain [Fluorine-based activator aqueous solution 1].

-Synthesis of low molecular weight polyester-
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 propylene oxide 3 mol adduct, 208 parts by mass of terephthalic acid, adipic acid 46 parts by mass and 2 parts by mass of dibutyltin oxide were added, reacted at 230 ° C. for 7 hours under normal pressure, and further reacted for 5 hours at a reduced pressure of 10 mmHg to 15 mmHg. Then, 44 parts by mass of trimellitic anhydride was added to the reaction vessel. The mixture was reacted at 180 ° C. for 3 hours under normal pressure to obtain [Low molecular polyester 1].
The obtained [Low molecular weight polyester 1] had a number average molecular weight of 2,300, a weight average molecular weight of 6,700, a glass transition temperature (Tg) of 43 ° C., and an acid value of 25 mgKOH / g.

-Synthesis of intermediate polyester and prepolymer-
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 added, reacted at 230 ° C. under normal pressure for 7 hours, and further reacted for 5 hours at a reduced pressure of 10 mmHg to 15 mmHg to obtain [Intermediate Polyester 1].
The obtained [Intermediate polyester 1] had a number average molecular weight of 2,200, a weight average molecular weight of 9,700, a glass transition temperature (Tg) of 54 ° C., an acid value of 0.5 mgKOH / g, and a hydroxyl value of 52 mgKOH / g. .
Next, 410 parts by mass of [Intermediate Polyester 1], 89 parts by mass of isophorone diisocyanate, and 500 parts by mass of ethyl acetate are placed in a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen introduction pipe. The reaction was performed for a while to obtain [Prepolymer 1]. [Prepolymer 1] obtained had a free isocyanate mass% of 1.53%.

-Synthesis of ketimine-
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 4 hours and 30 minutes to obtain [ketimine compound 1]. The amine value of the obtained [ketimine compound 1] was 417.

-Synthesis of master batch (MB)-
1,200 parts by weight of water, carbon black (Printex 35, manufactured by Dexa, 600 parts by weight of DBP oil absorption = 42 ml / 100 mg, pH = 9.5), 1200 parts of polyester resin, Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) The mixture was kneaded at 120 ° C. for 1 hour using two rolls, rolled and cooled, and pulverized with a pulverizer to obtain [Masterbatch 1].

-Preparation of oil phase-
378 parts by weight of [low molecular polyester 1], 95 parts by weight of carnauba wax, and 947 parts by weight of ethyl acetate are charged in a container equipped with a stir bar and a thermometer. After maintaining for 5 hours, it was cooled to 30 ° C. in 1 hour. Next, 500 parts by mass of [Masterbatch 1] and 500 parts by mass of ethyl acetate were charged in a container and mixed for 1 hour to obtain [Raw material solution 1].
[Raw material solution 1] 1,324 parts by mass were transferred to a container, and using a bead mill (Ultra Visco Mill, manufactured by Imex Co., Ltd.) Carbon black and wax were dispersed under the conditions of 80% by volume filling and 3 passes. Next, 1324 parts of a 65% by weight ethyl acetate solution of [low molecular weight polyester 1] was added, followed by two passes with the bead mill under the above conditions to obtain [Pigment / Wax Dispersion 1]. [Pigment / Wax Dispersion 1] had a solid content (130 ° C., 30 minutes) of 50% by mass.

-Emulsification and solvent removal-
[Pigment / Wax Dispersion 1] 749 parts by mass, [Prepolymer 1] 115 parts by mass, [Ketimine Compound 1] 2.9 parts by mass are placed in a container and TK homomixer (manufactured by Tokushu Kika Co., Ltd.) at 6,500 rpm After mixing for 3 minutes, 1,200 parts by mass of [Aqueous phase 1] was added to the container and mixed with a TK homomixer at 13,000 rpm for 40 minutes to obtain [Emulsion slurry 1].
Next, [Emulsion slurry 1] was put into a container equipped with a stirrer and a thermometer, and after removing the solvent at 30 ° C. for 10 hours, aging was carried out at 45 ° C. for 7 hours to obtain [Dispersion slurry 1]. .

-Cleaning, fluorine activator treatment, drying, and air sieving-
[Dispersion Slurry 1] 100 parts by mass were filtered under reduced pressure, and then subjected to the following treatment.
(1) 100 parts by mass of ion-exchanged water was added to the filter cake, mixed with a TK homomixer (rotation speed: 12,000 rpm for 10 minutes), and then filtered.
(2) 100 parts by mass of a 10% by mass aqueous sodium hydroxide solution was added to the filter cake of (1), mixed with a TK homomixer (30 minutes at 12,000 rpm), and then filtered under reduced pressure.
(3) 100 parts by mass of 10% by mass hydrochloric acid was added to the filter cake of (2), mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered.
(4) Add 300 parts by mass of ion-exchanged water to the filter cake of (3), mix with a TK homomixer (10 minutes at 12,000 rpm) and then filter twice to obtain [Filter cake 1]. It was.
(5) Put 630 parts by mass of [Filter cake 1] and 2,928 parts by mass of ion-exchanged water into a container, and stir with a three-one motor (manufactured by Shinto Kagaku Co., Ltd.) (rotation speed: 400 rpm for 5 minutes) at 30 ° C. Heat to. While maintaining the rotation speed and temperature, 11 parts by mass of [Fluoroactive aqueous solution 1] was added dropwise. It stirred for 60 minutes after completion | finish of dripping, and filtered, and obtained the filter cake 1 after a fluorine-type activator process.
The obtained [Filtered cake 1 after treatment with fluorinated activator] was dried at 45 ° C. for 48 hours in a circulating drier.
Then, it was sieved with a mesh having an opening of 75 μm to prepare a toner.

  1.0 part by mass of silica fine powder (hexamethyldisilazane treatment) having an average particle diameter of 15 nm and titanium oxide fine powder (isobutyltrimethoxysilane treatment) having an average particle diameter of 15 nm are obtained with respect to 100 parts by mass of the obtained toner. Then, 1.5 parts by mass of silica powder (hexamethyldisilazane treatment) having an average particle diameter of 90 nm and 1.5 parts by mass were mixed with a Henschel mixer and sieved to prepare [Toner A].

(Production Example 2)
<Preparation of Toner B>
Toner B was produced in the same manner as in Production Example 1 except that the emulsification and solvent removal steps in Production Example 1 were changed as follows.

-Emulsification and solvent removal-
[Pigment / Wax Dispersion 1] 749 parts by mass, [Prepolymer 1] 115 parts by mass, and [Ketimine Compound 1] 2.9 parts by mass are put in a container, and a TK homomixer (manufactured by Tokushu Kika Co., Ltd.) is used. After mixing at 6,500 rpm for 4 minutes, 1,200 parts by mass of [Aqueous phase 1] was added to the container, and mixed with a TK homomixer at 16,000 rpm for 40 minutes to obtain [Emulsion slurry 2]. [Emulsion slurry 2] was put into a container equipped with a stirrer and a thermometer, and after removing the solvent at 30 ° C. for 8 hours, aging was carried out at 45 ° C. for 7 hours to obtain [Dispersion slurry 2].

(Production Example 3)
<Preparation of Toner C>
-Constituent materials of toner-
Polyol resin as binder resin (1/2 outflow start temperature 118 ° C.) 98 parts by weight Carnauba wax as release agent 2.5 parts by weight Carbon black for black toner as colorant (CI Pigment Black 7) ... 5 parts by mass Salicylic acid derivative zinc salt as a charge control agent (E-84, manufactured by Orient Chemical Co., Ltd.) ... 2.5 parts by mass A constituent material of the toner is blended with a blender. Then, the mixture was melt-kneaded with a twin screw extruder heated to 100 ° C to 110 ° C. The kneaded product was allowed to cool and then roughly pulverized with a cutter mill, pulverized with a fine pulverizer using a jet stream, and then, mother colored particles C were obtained using an air classifier.
Next, 100 parts by mass of the base colored particles C, 1.0 part by mass of silica fine powder (hexamethyldisilazane treatment) having an average particle diameter of 15 nm and titanium oxide fine powder (isobutyltrimethoxysilane) having an average particle diameter of 15 nm Treatment) 0.5 parts by mass and 1.5 parts by mass of silica fine powder (hexamethyldisilazane treatment) having an average particle diameter of 90 nm were mixed with a Henschel mixer and then sieved. Thus, toner C was produced.

Next, Table 1 shows the weight average particle diameters of the produced toners A to C.

(Production Example 4)
<Creation of carrier>
・ Acrylic resin solution (solid content 50% by mass) 21.0 parts by mass ・ Guanamine solution (solid content 70% by mass) 6.4 mass parts ・ Alumina particles [average particle size 0.3 μm, specific resistance 10 ¹⁴ (Ω · cm)] 7.6 parts by mass Silicone resin solution [solid content 23% by mass, SR2410, manufactured by Toray Dow Corning Silicone Co., Ltd.] 65.0 parts by mass Aminosilane [ Solid content 100% by mass, SH6020, manufactured by Toray Dow Corning Silicone Co., Ltd.)] ... 1.0 part by massToluene ... 60 parts by massButyl cellosolve ... 60 parts by mass Dispersed to obtain a coating film forming solution composed of an acrylic resin containing alumina particles and a silicone resin. The sintered ferrite powder [(MgO) _1.8 (MnO) _49.5 (Fe ₂ O ₃ ) _48.0 , average particle size 35 μm] was used as the core material, and the coating film forming solution was coated on the surface of the core material. The film was coated with a Spira coater (Okada Seiko Co., Ltd.) so that the film thickness of the film became 0.15 μm, dried, and left to stand at 150 ° C. for 1 hour in an electric furnace and fired. After cooling, the ferrite powder bulk was pulverized using a sieve having an aperture of 106 μm to obtain a carrier having a weight average particle diameter D of 35 μm.

<Production of developer>
7 parts by mass of the produced toners A to C and 93 parts by mass of the produced carrier were mixed for 10 minutes by a ball mill to produce developers A to C.

(Production Example 5)
-Production sleeve development-
The material and configuration of the developing sleeve are appropriately selected according to the type of developer used. For example, in the case of a two-component developer, a developing sleeve provided with a magnetic field generating means such as a magnet is used, and a nonmagnetic metal such as SUS or aluminum is mainly used as the material. In recent years, it has become a mainstream to roughen the surface of the developing sleeve for the purpose of improving transportability when the two-component developer on the developing sleeve is transported to the developing region.
In addition, the surface of the developing sleeve can be roughened by a sandpaper method in which the surface of the developing sleeve is rubbed with sandpaper, a bead blasting method using spherical particles, a sandblasting method using regular particles, or a mixing method thereof, or a chemical method. The chemical etching method by a process etc. are mentioned. Examples of the regular particles used in the sandblasting method include various steel balls made of metals such as stainless steel, aluminum, steel, nickel and brass having a specific particle diameter, or various hard balls such as ceramic, plastic and glass beads. Can be used.
In the present invention, a sleeve having a diameter of 30 mm and an axial length of 353 mm is prepared by the above-described method using the materials shown in Table 2 (SUS, aluminum), and the surface is blasted to have an arbitrary average mountain interval Sm. The developing sleeves 1 to 7 were prepared by roughening the surface.
For each of the produced developing sleeves, the average crest distance Sm (μm) on the surface was measured as follows. The results are shown in Table 2.

<Measurement of mean mountain spacing Sm>
A surface roughness meter (Surfcom 1440D, manufactured by Tokyo Seimitsu Co., Ltd., JIS B0601-1982 standard) was used for measurement of the average crest spacing Sm of the developing sleeve. As shown in FIG. 2, the average crest interval Sm is from the first mountain-to-valley crossing point across the center line C of the roughened cross-sectional curve D to the next mountain-to-valley crossing point. When the interval is S1, and the subsequent crossing point intervals are S2, S3,..., Sn (n indicates the total number of crossing points in the reference length), these values are arithmetically averaged. It is represented by the following formula (1). That is, qualitatively. The average peak interval Sm indicates the average interval between the peak on the surface of the developing sleeve and the adjacent peak.
Sm = (S1 + S2 + ... + Sn) / n ... Equation (1)

The produced developers A to C and developing sleeves 1 to 7 are mounted on an image forming apparatus (made by Ricoh Co., Ltd., a modified machine of RICOH Pro C900) in the combination shown in Table 3, and image formation is performed as follows. Density unevenness of halo and solid images was evaluated. The results are shown in Table 3.
As shown in FIG. 1, the image forming apparatus has a first developing sleeve 2a and a second developing sleeve 2b, and the first developing sleeve 2a and the second developing sleeve 2b are in opposite directions. The first developing sleeve rotates and rotates in the direction opposite to the image carrier 1.
However, only Comparative Example 4 is configured such that the first developing sleeve 2 a and the second developing sleeve 2 b rotate in the same direction as the image carrier 1.
In the image forming apparatus, a RICOH Pro C900 scorotron charger manufactured by Ricoh Co., Ltd. is used as charging means.

<Image formation>
Under normal temperature and normal humidity (25 ° C., 60% RH), the initial potential of the image carrier was set so that Vd (dark part potential) of the image carrier was −800 V and Vl (bright part potential) was −200 V.
As paper, Ricoh Co., Ltd. 6200 paper (A4 size, T eye) was used. After passing 5,000 sheets with an image area of 5%, Ricoh Co., Ltd. 6200 paper (A3 size, Y eye) The following items were evaluated by outputting one evaluation image. In addition, the evaluation image used the image which arranged the solid patch in the four corners and the center in the whole surface halftone.

<< Hello evaluation >>
The degree of white spots in the boundary portions between the four solids and the halftone in all four places at four corners and one in the center was visually confirmed and evaluated according to the following criteria.
〔Evaluation criteria〕
◎: Visually, there is no halo in the image ○: Visually, there is a slight halo in the image, and there is no problem in actual use △: Visually, there is a halo in the image, there is a problem in actual use ×: Visually There is a noticeable halo in the image, which is worse than △

<< Density unevenness of solid image >>
The image density was measured at all four locations at four corners at four locations and at one central location, solid uniformity was calculated according to the following formula, and ranking was performed according to the following criteria.
Density unevenness of solid image = (maximum value of image density−minimum value of image density) × 100 (%)
The image density was measured under the condition of an incident angle of 60 ° using a gloss meter manufactured by Nippon Denshoku Industries Co., Ltd., and the average value of the image density at five locations was obtained.
〔Evaluation criteria〕
Rank 5: Less than 15% Rank 4: 15% or more but less than 30% Rank 3: 30% or more but less than 50% Rank 2: 50% or more but less than 70% Rank 1: 70% or more

<< Toner fusion to developing means (sleeve fixing) >>
After the halo evaluation and the solid image density unevenness evaluation, the paper was further passed up to 50K (50,000 sheets) with an image area of 5%, and then the sleeve fixing [visual evaluation] was evaluated.
Evaluation was performed in five stages from rank 5 (no sticking) to rank 1 (many sticks). Three or more ranks are acceptable levels.

* For Comparative Example 4 only, the first and second developing sleeves and the image carrier rotate in the same direction.

  The image forming apparatus, the image forming method, and the process cartridge of the present invention are capable of forming a high-quality image that suppresses abnormal images such as halo and solid image density unevenness, and at the same time multi-stage development that achieves high-speed compatibility and durability. Therefore, it can be widely used in full-color copiers, full-color laser printers, full-color plain paper fax machines and the like using a direct or indirect electrophotographic multicolor image development system.

DESCRIPTION OF SYMBOLS 1 Image carrier 2 Developing sleeve 2a 1st developing sleeve 2b 2nd developing sleeve 3 Developing means 10, 10Y, 10M, 10C, 10K Image bearing body 11, 11Y, 11M, 11C, 11K Charging means 12, 12Y, 12M , 12C, 13K Exposure unit 13, 13Y, 13M, 13C, 13K Development unit 14 Transport roller 15 Recording medium 16, 16Y, 16M, 16C, 16K Transfer unit 17, 17Y, 17M, 17C, 17K Cleaning unit 18 Static elimination unit 19 Transfer Conveying belt 20Y, 20M, 20C, 20K Image forming element 21 Paper feed roller 22 Registration roller 23 Transfer means (secondary transfer means)
24 Fixing means

Japanese Patent Laid-Open No. 11-161017 Japanese Patent Laid-Open No. 10-171252 JP 2002-268386 A Japanese Patent No. 4378143

Claims (8)

An image carrier, a charging unit for charging the surface of the image carrier, an exposure unit for exposing the charged surface of the image carrier to form an electrostatic latent image, and the electrostatic latent image with toner and a carrier. An image forming apparatus having at least developing means for forming a visible image by developing with a developer including
The developing means includes at least a first developing member and a second developing member, the first developing member and the second developing member rotate in opposite directions, and the first developing member is Rotating in the same direction as the image carrier, the average crest distance on the surface of the first developing member is Sm1, the average crest distance on the surface of the second developing member is Sm2, and the weight average particle diameter of the developer carrier is D. An image forming apparatus satisfying the following expressions: Sm1 ≦ D, D ≦ Sm2, and Sm1 ≠ Sm2 .   Toner in which at least a compound having an active hydrogen group, a polymer having a site capable of reacting with the compound having an active hydrogen group, a polyester resin, a colorant, and a release agent are dissolved or dispersed in an organic solvent. The image forming apparatus according to claim 1, which is obtained by reacting a material liquid in an aqueous medium.   The image forming apparatus according to claim 2, wherein the toner has a weight average particle diameter of 2 μm to 6 μm.   4. The image forming apparatus according to claim 1, wherein the image forming apparatus is a tandem type in which a plurality of image forming elements including at least an image carrier, a charging unit, and a developing unit are arranged.   The image forming apparatus according to claim 1, wherein the charging unit applies a DC voltage on which an alternating voltage is superimposed.   The image forming apparatus according to claim 1, wherein the charging unit is in the form of a roller and is disposed in proximity to and non-contact with the image carrier. A charging step for charging the surface of the image carrier, an exposure step for exposing the charged image carrier surface to form an electrostatic latent image, and the electrostatic latent image using a developer containing toner and a carrier. An image forming method including at least a developing step of developing to form a visible image,
The developing step includes at least a first developing member and a second developing member, the first developing member and the second developing member rotate in opposite directions, and the first developing member is Rotating in the same direction as the image carrier, the average crest distance on the surface of the first developing member is Sm1, the average crest distance on the surface of the second developing member is Sm2, and the weight average particle diameter of the developer carrier is D. In this case, the image forming method is performed using a developing unit that satisfies the following formulas: Sm1 ≦ D, D ≦ Sm2, and Sm1 ≠ Sm2 . An image forming apparatus main body having at least an image carrier and developing means for developing the electrostatic latent image formed on the image carrier using a developer containing toner and a carrier to form a visible image A process cartridge that can be attached to and detached from
The developing means includes at least a first developing member and a second developing member, the first developing member and the second developing member rotate in opposite directions, and the first developing member is Rotating in the same direction as the image carrier, the average crest distance on the surface of the first developing member is Sm1, the average crest distance on the surface of the second developing member is Sm2, and the weight average particle diameter of the developer carrier is D. A process cartridge characterized by satisfying the following expressions: Sm1 ≦ D, D ≦ Sm2, and Sm1 ≠ Sm2 .