JP2010249908A - Toner, toner manufacturing method and image forming apparatus using the same - Google Patents

Abstract

Toner having a uniform particle size is produced efficiently by removing fine powder of 2.5 μm or less.
A dispersion 6A in which colored resin particles are dispersed in an aqueous medium is injected into a centrifuge having a non-circular cylindrical tank 3A on an inner wall surface having a rotation axis in the vertical direction and rotated. A toner that separates the colored resin particles 5A adhering to the inner wall surface after discharging the dispersion 7A in the cylindrical vessel after the particle component adheres to the inner wall surface of the cylindrical vessel by centrifugal force, and a method for producing the same.
[Selection] Figure 1

Description

  The present invention relates to a toner for developing an electrostatic charge image used for developing an electrostatic latent image on a latent image carrier in an image output apparatus such as a copying machine, a printer, or a fax machine, and a method for producing the toner. The present invention relates to an image forming apparatus using.

  In image output devices such as electrophotographic copiers, printers, fax machines, etc., the resolution of printed images is improved, the gradation is improved, the amount of waste toner is reduced, and the energy consumption is reduced by lowering the fixing temperature. Due to demands for improving image characteristics in full-color images, the toner particles used for image formation for image formation are becoming smaller.

  However, the toner having a small particle diameter is likely to be scattered, causing problems of toner scattering and toner contamination inside the image forming apparatus, and further, it is a problem to prevent the toner from being diffused into the atmosphere from the apparatus. Conventionally, toner scattering suppression technology has been developed. However, the importance of toner scattering suppression is further increased by reducing the toner particle size.

  The toner has two adhesion forces, namely an electrostatic force that can control the electric field and a van der Waals force that cannot control the electric field. If the toner particle size is reduced, the van der Waals force ratio becomes larger than the electrostatic force force, so that it becomes difficult to control the toner by an electric field. Further, when the toner has a small particle diameter, the air resistance becomes larger than that of gravity settling. For this reason, when toner that is not subjected to electric field control becomes scattered due to development or the like, it is likely to be dissipated into the atmosphere outside the apparatus by riding on an air current such as a cooling fan of the apparatus.

  On the other hand, there is a growing interest in the health effects of airborne particulate matter, especially fine particles. It is mentioned that a standard for microparticles of 2.5 μm or less, which is called PM2.5 in the US environmental standards and WHO guidelines, and that causes diseases for respiratory organs, etc. has been added. In Japan, in view of the ongoing discussion on the establishment of environmental standards, it is important to prevent toner having a particle size of 2.5 μm or less from being released into the atmosphere.

In order to separate particles with a specific particle size from the toner, it is transferred to a vertical cylindrical kettle and allowed to stand for 2 hours. After settling and separation, 50% of the total amount is opened by opening the shut-off valve on the side of the kettle. Has been proposed to classify powder containing 50% by number or more of particles having a volume average particle diameter of 7 μm or less by discharging as a supernatant (for example, see Patent Document 1). However, this method has a problem in industrial production of toner because it takes a long time to settle.
Further, it has been proposed to prepare a toner having a volume average particle diameter of 6 to 8 μm by applying a centrifugal force of 1000 to 3000 G using a decanter type centrifuge having two functions of sedimentation separation and filtration and dehydration. (For example, refer to Patent Document 2).
In this method, although the toner has an average particle diameter of 6.5 μm, it contains 6% of toner having a particle size of 3 μm or less, and does not sufficiently meet the PM2.5 standard.

JP 2002-28527 A JP 2004-133326 A

In the conventional toner classification method, it is necessary to leave the toner for a long time, or the particle size distribution of the obtained toner is less than 3 μm. The reduction rate of toner of 3 μm or less was not sufficient.
An object of the present invention is to provide a toner that does not contain fine powder, and in particular, to provide a method for efficiently producing a toner having a uniform particle size obtained by reliably removing toner having a particle size of 2.5 μm or less. In addition, it is an object of the present invention to provide a toner in which fine external additives added to the toner prevent scattering into the air, and an image forming apparatus using the toner. It is.

According to the present invention, a dispersion liquid in which colored resin particles are dispersed in an aqueous medium is injected into a centrifuge having a non-circular cylindrical tank on an inner wall surface having a rotation axis in the vertical direction, and the cylinder is rotated. This is a toner manufacturing method in which after the particle component adheres to the inner wall surface of the tank by centrifugal force, the dispersion liquid in the cylindrical tank is discharged, and then the colored resin particles attached to the inner wall surface are separated.
In this way, the dispersion containing the colored resin particles is applied to the cylindrical tank wall by rotating the cylindrical tank having a non-porous wall surface to apply centrifugal force, whereby the colored resin particles are applied to the cylindrical tank wall surface by the action of the centrifugal force. Most of the fine powder that remains in the dispersion remains in the dispersion and is also washed away from the cake-like deposit by the dispersion and discharged, so a toner with a low content of fine powder particles of 2.5 μm or less can be obtained. It is possible to manufacture.

The centrifugal force is 500 to 900 G, and the rotation time is 5 to 30 minutes.
Thus, the centrifugal force applied to the dispersion by the method of the present invention is smaller than the centrifugal force applied during conventional wet classification, and the time for applying the centrifugal force is short, so when a large centrifugal force is applied for a long time Compared to the above, a relatively large void is formed inside the particle precipitation layer, so that when the remaining dispersion is discharged, fine particles having a small particle size are removed together with the discharged liquid. It is possible to produce a toner with a small content of particle-like particles.

  Further, in the toner manufacturing method, the colored resin particles attached to the inner wall surface after separating the dispersion liquid in the cylindrical tank are dispersed in an aqueous medium, injected into the centrifuge, and the above steps are repeated. In this way, after the cake-like precipitate separated from the dispersion is dispersed in the aqueous medium, it is injected into the cylindrical tank again and the above steps are repeated to obtain a fine powdery form of 2.5 μm or less. It is possible to produce a toner with a low toner content.

Further, in the toner production method, the circularity of the colored resin particles is 0.96 or more.
As described above, since the circularity of the colored resin particles is 0.96 or more and has a shape close to a sphere, even when cake-like precipitates are formed by centrifugal force in the cylindrical tank, precipitation is also caused. To provide a toner in which a fine powdery toner having a particle size of 2.5 μm or less from a space between particles is easily separated together with the dispersion, and a content of the fine powdery toner having a particle size of 2.5 μm or less is small. Is possible.

In the toner production method, the number mode diameter of the colored resin particles is 3 μm or more and 6 μm or less.
As described above, the toner production method of the present invention can produce a toner having a sharp particle size distribution range.

The colored resin particles are colored resin particles produced by emulsifying a composition containing at least a synthetic resin, a colorant, and a wax in an aqueous medium and adding the electrolyte together. This is a method for producing the toner.
The toner production method of the present invention is a small particle obtained by adding an electrolyte to particles obtained by emulsifying a composition containing at least a synthetic resin, a colorant, and a wax in an aqueous medium, and then adding them together. It is suitable as a method for separating fine powder particles from toner having a diameter.

Further, the dispersion liquid in which the colored resin particles are dispersed in the aqueous medium is injected into a centrifuge having a cylindrical tank having no opening on the inner wall surface having a rotation axis in the vertical direction, and rotated, After the particle component adheres to the inner wall surface of the cylindrical tank by centrifugal force, the rotation of the cylindrical tank is stopped, and after classifying by discharging the dispersion liquid in which the ratio of particles having a small particle diameter in the cylindrical tank is increased, This is a toner obtained by drying colored resin particles adhering to the inner wall surface of a cylindrical tank.
In the toner of the present invention, the colored resin particles are applied to the wall surface of the cylindrical tank by the action of the centrifugal force by applying a centrifugal force by rotating the dispersion containing the colored resin particles in a cylindrical tank having a non-porous wall surface. Most of the particles with a small particle size remain in the dispersion and are washed away from the cake-like deposit by the dispersion and discharged, so fine particles of 2.5 μm or less This is a toner with a low content.

The toner of the present invention is a toner in which 0.05 to 2 parts by mass of silicone oil is blended per 100 parts by mass of the colored resin particles after drying the colored resin particles attached to the inner wall surface of the cylindrical tank.
As described above, by adding the silicone oil, it is possible to prevent scattering of the fine powder toner without adversely affecting the image quality.

In addition, the toner includes alumina fine particles having a phase angle θ of | 80 ° | or less as an external additive in an AC frequency range of 1 kHz to 10 kHz in the AC impedance method.
As described above, since the toner includes alumina fine particles having a phase angle θ of | 80 ° | or less in an AC frequency range of 1 kHz to 10 kHz in the AC impedance method as an external additive, even when jumping development is performed, development is performed. It is preferable because scattering and fogging from the gap can be suppressed.

In addition, a photosensitive member carrying an electrostatic latent image is disposed opposite to the photosensitive member in a non-contact state, and the electrostatic latent image carried on the photosensitive member is dispersed with colored resin particles in an aqueous medium. The dispersion is injected into a centrifuge equipped with a cylindrical tank that does not have a hole in the inner wall surface having a rotation axis in the vertical direction, and the particle component adheres to the inner wall surface of the cylindrical tank by centrifugal force. The colored resin particles attached to the inner wall surface of the cylindrical tank are dried after classification by discharging the dispersion liquid in which the ratio of particles having a small particle diameter in the cylindrical tank is increased after stopping the rotation of the cylindrical tank. The toner is developed by jumping development in which the toner is caused to fly between the developing means held in a non-contact state and the electrostatic latent image carrier with the toner thus adhered to the electrostatic latent image on the electrostatic latent image carrier. An image forming apparatus having a developing machine.
As a result, it is possible to provide an image forming apparatus that can form an image with excellent toner quality with less scattering of toner into the surrounding environment.

FIG. 1 is a diagram illustrating a method for performing classification and dehydration according to the present invention. FIG. 1A is a diagram illustrating a state where rotation is performed, FIG. 1B is a diagram illustrating a state where rotation is stopped, and FIG. 1C is a diagram illustrating the remaining dispersion liquid. It is a figure explaining the state removed, and all are sectional drawings. FIG. 2 is a diagram illustrating an example of an image forming apparatus according to the present invention. FIG. 3 is a diagram for explaining the image forming mechanism of the present invention, FIG. 3 (A) is a diagram for explaining the image forming unit explained in FIG. 2 in an enlarged manner, and FIG. It is a figure explaining a process. 4A and 4B are diagrams for explaining the developing means of the present invention, FIG. 4A is a side view, and FIG. 4B is an enlarged cross-sectional view of one end of the developing roll.

  The present invention provides a toner that suppresses scattering of fine powder particles from an image forming apparatus while having a small particle diameter toner, and an image forming apparatus using the same by classifying the toner in a liquid. What has been found, and in particular, has found to provide a toner that suppresses the generation of microparticles of 2.5 μm or less, which are considered to cause diseases for respiratory organs, and an image forming apparatus using the toner. It is.

The toner of the present invention and the toner manufacturing method were prepared by emulsifying a colored resin particle by emulsifying a composition containing a synthetic resin and a colorant in an aqueous medium and adding the electrolyte together to produce the toner. The toner is preferably made of colored resin particles.
A method for producing such toner will be described below in the order of each process.
1st process: The process of emulsifying the resin solution which has a polyester resin and an organic solvent as an essential component in an aqueous medium, and forming microparticles | fine-particles,
Second step: combining the fine particles to produce an aggregate of the fine particles,
Third step: a step of removing the organic solvent contained in the aggregate,
Fourth step: a step of classifying particles from an aqueous medium and separating the particles;
Fifth step: The step comprises drying the separated particles to produce a toner. The toner in the present invention means a product obtained by drying the aggregate produced in the fifth step.

  In the first step, first, a polyester resin is introduced into an organic solvent, and the polyester resin is dissolved and dispersed to prepare a mixture containing the polyester resin and the organic solvent. In this case, one or more selected from various colorants, release agents or charge control agents, or other additives can be used together with the polyester resin as the toner raw material. In the present invention, it is preferable to disperse the colorant in the organic solvent together with the polyester resin, and it is particularly preferable to dissolve or disperse various additives such as a release agent and a charge control agent.

As a means for dissolving or dispersing a polyester resin and various additives such as a colorant, a release agent, and a charge control agent in an organic solvent, the following method is preferably used.
As a first method, a mixture containing various additives such as the above-mentioned polyester resin, colorant, release agent, charge control agent, etc. is used using a pressure kneader, a heated two-roll, two-screw extrusion kneader, etc. The polyester resin to be used is kneaded by heating to a temperature not lower than the softening point and not higher than the thermal decomposition temperature. At this time, the colorant and the like may be melt-kneaded as a master batch. Then, the method of preparing the kneading | mixing chip | tip obtained by melt | dissolving or disperse | distributing in the organic solvent with stirrers, such as a Desper (made by Asada Iron Works), can be mentioned.
As a second method, a polyester resin and various additives such as a colorant, a release agent, and a charge control agent are mixed with an organic solvent, and this is wet-kneaded by a ball mill or the like. In this case, the colorant, the release agent, and the like may be mixed after preliminary dispersion separately in advance.

The compounding means of the polyester resin and other components includes a resin solution in which the polyester resin is dissolved in an organic solvent in advance in a mixing / dispersing machine using media such as a ball mill, a bead mill, a sand mill, and a continuous bead mill. Add a colorant and a release agent, stir and disperse to make a master batch, and further mix a polyester resin for dilution and an additional organic solvent to finely disperse the colorant and release agent in the organic solvent. The method of manufacturing a resin solution can be mentioned.
At this time, pressurize the low-viscosity polyester resin and the colorant or the release agent in advance, rather than putting the colorant or the release agent untreated directly into a mixing / dispersing machine such as a ball mill. It is preferable to use a master batch obtained by kneading and dispersing with a kneader and two heated rolls.
According to the above production method, since the gel component which is a polymer component of the polyester resin is not cut, it is preferable to the first method in which the gel component is simply dispersed by melt kneading.

  Organic solvents for dissolving or dispersing colorants and mold release agents used in combination with polyester resins include hydrocarbons such as pentane, hexane, heptane, benzene, toluene, xylene, cyclohexane, petroleum ether; acetone, methyl ethyl ketone And ketones such as methyl isobutyl ketone; esters such as ethyl acetate and butyl acetate are used. These solvents can be used in combination of two or more, but from the viewpoint of solvent recovery, it is preferable to use the same type of solvent alone. The organic solvent is preferably a solvent that dissolves the binder resin, has a relatively low toxicity, and has a low boiling point that is easy to remove the solvent in a subsequent process. As such a solvent, methyl ethyl ketone is most preferable.

  As a method of emulsifying a mixture containing a polyester resin and an organic solvent in an aqueous medium, a mixture prepared by the above method of a colorant and an organic solvent used in combination with a polyester resin, in the presence of a basic neutralizing agent, It is preferable to mix and emulsify with an aqueous medium. In this step, it is preferable to gradually add water or an aqueous medium that is a liquid containing water as a main component to a mixture of a polyester resin, a colorant, and the like and an organic solvent. In that case, by gradually adding water to the organic continuous phase of the mixture, a discontinuous phase in which an aqueous phase is present in the oily phase is generated, and by further adding water, an aqueous phase is added. A phase inversion into a discontinuous phase consisting of an oily phase therein forms a suspension / emulsion liquid in which the mixture floats as particles, ie, droplets, in an aqueous medium. Hereinafter, the change from the discontinuous phase in which the aqueous phase is present in the oil phase to the discontinuous phase composed of the oil phase in the aqueous phase is also referred to as phase inversion emulsification.

  In phase inversion emulsification, water is added so that the ratio of water to the total amount of the organic solvent and water is 30 to 70% by mass. More preferably, it is 35-65 mass%, and it is especially preferable that it is 40-60 mass%. The aqueous medium used is preferably water.

The polyester resin used in the present invention is preferably an acidic group-containing polyester resin. By neutralizing the acidic group, a polyester resin having self-water dispersibility that is stably dispersed in water (hereinafter referred to as self-water dispersion). (It is also referred to as a functional resin). The acid value of the self-water dispersible polyester resin used in the present invention is preferably 1-20. The resin having self-water dispersibility becomes an anionic type by neutralizing an acidic group with a basic neutralizing agent. As a result, the hydrophilicity of the resin is increased, and the resin can be stably dispersed in the aqueous medium without using a dispersion stabilizer or a surfactant. Examples of the acidic group include an acidic group such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group. Among these, a carboxyl group is preferable from the viewpoint of toner charging characteristics. Examples of the basic substance for neutralization include inorganic bases such as sodium hydroxide, potassium hydroxide, and ammonia water, and organic bases such as diethylamine, triethylamine, and isopropylamine. Of these, inorganic bases such as aqueous ammonia, sodium hydroxide, and potassium hydroxide are preferred.
In order to disperse the polyester resin in the aqueous medium, there is a method of adding a dispersion stabilizer such as a suspension stabilizer or a surfactant. However, the suspension stabilizer or the surfactant is added and emulsified. The method requires high shear forces. As a result, the generation of coarse particles and the particle size distribution become broad, which is not preferable. Therefore, in the present invention, it is preferable to use a self-water dispersible resin and neutralize the acidic group of the resin with a basic compound.

  Examples of a method for neutralizing a carboxyl group which is an acidic group of a polyester resin with a base include, for example, a method of producing a mixture containing a polyester resin having an acidic group, a colorant, a wax and an organic solvent, and then neutralizing with a base. Alternatively, there may be mentioned a method of neutralizing the acidic group of the polyester resin contained in the mixture at the time of phase inversion emulsification after previously mixing a basic neutralizing agent in an aqueous medium.

  The phase inversion emulsification may be carried out by adding the mixture in an aqueous medium and emulsifying, or by preparing a mixture containing an acidic group polyester resin, a colorant, a wax and an organic solvent, and then using a base. The method of combining the method of neutralizing and the method of adding an aqueous medium in the said mixture can be mentioned. The latter method is preferable because the particle size distribution becomes narrow.

  In the phase inversion emulsification, various types of dispersing machines can be used. However, in order to promote uniform coalescence, rather than using a dispersing machine that requires a high share, the agitation conditions at the same time are more important. , Turbine blades, fiddler blades, full-zone blades, Max blend blades (registered trademark), and meniscus blades. Among them, it is preferable to use a large blade having excellent uniform mixing characteristics even at a low rotation, such as a Max blend blade or a full zone blade. The peripheral speed of the stirring blade for generating a uniform unity is preferably 0.2 to 10 m / s, and more preferably stirring with a low shear of less than 0.2 to 8 m / s. In particular, 0.2 to 6 m / s is preferable. If the peripheral speed of the stirring blade is faster than 10 m / s, it is not preferable because fine particles remain.

  On the other hand, if the peripheral speed is lower than 0.2 m / s, stirring is not uniform, phase inversion does not occur uniformly, and coarse particles tend to be generated, which is not preferable. Further, the temperature during phase inversion emulsification is not preferable because the higher the temperature, the more coarse particles are generated. On the other hand, when the temperature is too low, the viscosity of the mixture containing the polyester resin and the organic solvent is increased, and the generation of coarse particles is increased. The temperature range during phase inversion emulsification is preferably 10 to 40 ° C. More preferably, it is the range of 20-30 degreeC.

  As described above, by performing phase inversion emulsification under low share using self-water dispersible resin, generation of fine powder and coarse particles can be suppressed, and as a result, uniform particle size distribution in the next coalescence process It becomes easy to produce agglomerates of fine particles having. In addition, when a polyester resin having no self-water dispersibility is used, or when phase inversion emulsification is performed under a high share, the generation of coarse particles or the low molecular weight component of the resin generates fine powder, and toner particles The particle size distribution of the toner is widened, and further, particles containing low molecular weight components are removed by sieving performed in the subsequent process, which causes the low temperature fixability of the toner to deteriorate. Such inconvenience does not occur by using a water dispersible resin or performing phase inversion emulsification under a low share.

  The 50% volume average particle size of the fine particles produced in the first step is more than 1 μm and not more than 6 μm, more preferably more than 1 μm and 4 μm. If it is 1 μm or less, when a colorant or a release agent is used, it is not preferable because it is not covered with a polyester resin, which adversely affects charging characteristics and development characteristics. If the particle size is large, the particle size of the toner to be obtained is limited. Therefore, it is necessary to make the particle size smaller than the particle size of the target toner, but if it is larger than 6 μm, coarse particles are likely to be generated. Therefore, it is not preferable. The particle size distribution of the fine particles produced in the first step is such that the ratio of the volume particle diameter of 10 μm or more is 2% or less, more preferably 1% or less, and the ratio of the volume particle diameter of 5 μm or more is 10% or less. Preferably it is 6% or less.

In the second step, the fine particles obtained in the first step are united to form an aggregate of the fine particles, thereby forming toner particles having a desired particle diameter. In the second step, desired aggregates can be obtained by appropriately controlling the amount of solvent, temperature, type or amount of dispersion stabilizer and electrolyte, stirring conditions and the like.
The present invention is a production method for obtaining an aggregate in a single step including the fusion step simultaneously with the aggregation as described above, and can obtain spherical or substantially spherical particles in a short time without heating. It has the feature that it can.

  In the second step of the present invention, the dispersion of fine particles obtained in the first step is diluted with water to adjust the amount of solvent. Thereafter, a dispersion stabilizer is added and coalescence is advanced by dropping an aqueous electrolyte solution in the presence of the dispersion stabilizer to obtain an aggregate having a predetermined particle diameter.

  The fine particles formed from the self-water dispersible resin obtained up to the first step are stably dispersed in the aqueous medium by the action of the electric double layer by the carboxylate. In the second step of the present invention, the particles are destabilized by adding an electrolyte that destroys or reduces the electric double layer to the aqueous medium in which the fine particles are dispersed. Examples of the electrolyte that can be used in the present invention include acidic substances such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, and oxalic acid. In addition, organic and inorganic water-soluble salts such as sodium sulfate, ammonium sulfate, potassium sulfate, magnesium sulfate, sodium phosphate, sodium dihydrogen phosphate, sodium chloride, potassium chloride, ammonium chloride, calcium chloride, sodium acetate, etc. It can be used effectively as an electrolyte. These electrolytes to be added for unity may be used alone or in combination of two or more kinds. Among them, monovalent cation sulfates such as sodium sulfate and ammonium sulfate are preferable for promoting uniform coalescence. In the production method of the present invention, the fine particles obtained in the first step are swollen by the solvent, and the electric double layer of the particles is in an unstable state due to the addition of the electrolyte, so that the low shear (low shear) Even if the particles collide with each other by agitation of force, coalescence easily proceeds.

  Further, only by adding an electrolyte or the like, the dispersion stability of the fine particles in the system is unstable, so the coalescence becomes non-uniform and coarse particles and aggregates are generated. In order to prevent agglomerates of fine particles produced by electrolytes or acidic substances from repeating reunion and forming aggregates larger than the target particle size, before adding electrolytes etc., hydroxyapatite It is necessary to add an inorganic dispersion stabilizer such as ionic or nonionic surfactant as a dispersion stabilizer. The dispersion stabilizer to be used is required to have a property capable of maintaining dispersion stability even in the presence of an electrolyte added later.

  Examples of the dispersion stabilizer having such characteristics include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester. , Polyoxyethylene sorbitan fatty acid esters and the like, or various nonionic emulsifiers such as pluronics, alkyl sulfate ester type anionic emulsifiers, and quaternary ammonium salt type cationic dispersion stabilizers. Among these, even if an anion type or nonionic type dispersion stabilizer is added in a small amount, the dispersion stability of the system is effective, which is preferable. The cloud point of the nonionic surfactant is preferably 40 ° C. or higher. The surfactants described above may be used alone or in combination of two or more. In the production method of the present invention, by adding an electrolyte in the presence of a dispersion stabilizer (emulsifier), nonuniform coalescence can be prevented, and as a result, a sharp particle size distribution range is obtained, Along with this, an improvement in yield is achieved.

  In the second step of the present invention, the obtained fine particle dispersion may be diluted with water. Thereafter, a dispersion stabilizer and an electrolyte are sequentially added to perform coalescence. Alternatively, it is preferable to adjust the amount of the solvent in the dispersion by adding an aqueous solution of a dispersion stabilizer and / or an electrolyte to obtain particles having a predetermined particle diameter. The amount of the solvent contained in the system after adding the electrolyte is preferably in the range of 5 to 25% by mass. Moreover, the inside of the range of 5-20 mass% is more preferable, and the inside of the range of 5-18 mass% is especially preferable. When the amount of the solvent is less than 5% by mass, the electrolytic mass required for coalescence is increased, which is not preferable. On the other hand, if the amount of the solvent is more than 25% by mass, the generation of aggregates due to non-uniform coalescence increases, and the amount of dispersion stabilizer added increases, which is not preferable.

  In the present invention, the shape of the toner particles after coalescence can be adjusted by adjusting the amount of the solvent. When the amount of solvent is in the range of 13 to 25% by mass, the degree of swelling of the fine particles by the solvent is large, so that spherical to substantially spherical particles can be easily obtained by coalescence. On the other hand, when the amount of the solvent is in the range of 5 to 13% by mass, the degree of swelling of the fine particles by the solvent is small, so that irregularly to substantially spherical toner particles can be easily obtained.

  The amount of the dispersion stabilizer to be used is preferably in the range of 0.5 to 3.0% by mass with respect to the solid content of the fine particles, for example. A range of 0.5 to 2.5% by mass is more preferable, and a range of 1.0 to 2.5% by mass is particularly preferable. If it is less than 0.5% by mass, the desired effect of preventing the generation of coarse particles cannot be obtained. On the other hand, if the amount is more than 3.0% by mass, coalescence does not proceed sufficiently even if the amount of the electrolyte is increased, and particles having a predetermined particle diameter cannot be obtained. As a result, fine particles remain and yield. Is not preferable.

  Moreover, it is preferable that the quantity of the electrolyte to be used exists in the range of 0.5-15 mass% with respect to solid content content of microparticles | fine-particles. It is more preferably within a range of 1 to 12% by mass, and particularly preferably within a range of 1 to 10% by mass. When the amount of the electrolyte is less than 0.5% by mass, the coalescence does not proceed sufficiently, which is not preferable. On the other hand, when the amount of the electrolyte is more than 15% by mass, the coalescence becomes non-uniform, which is not preferable because aggregates and coarse particles are generated and the yield is lowered.

  The temporary temperature is preferably in the range of 10 to 50 ° C. More preferably, it exists in the range of 20-40 degreeC, and it is especially preferable that it is 20-35 degreeC. When the temperature is lower than 10 ° C., it is difficult to perform coalescence, which is not preferable. On the other hand, when the temperature is higher than 50 ° C., the coalescence speed is increased, and aggregates and coarse particles are easily generated, which is not preferable. In the production method of the present invention, it is possible to produce aggregates by coalescence under low temperature conditions such as 20 to 40 ° C. Therefore, unlike the association method, it is not necessary to raise the temperature to 80 to 90 ° C. in order to fuse the fine particles after fusing.

In the first step of performing phase inversion emulsification in the present invention and the second step of performing coalescence, various embodiments can be employed.
Of these, preferred embodiments include the following.
A method in which fine particles are produced in the first step using a resin solution comprising a polyester resin and a colorant, or a release agent and a charge control agent, and the second step is performed.
A method in which fine particles are produced in the first step using a resin solution comprising a polyester resin and a colorant, or a mold release agent, and then the charge control agent dispersion is mixed to perform the second step.
-Producing fine particles comprising a polyester resin by the above-mentioned first step, separately preparing one or more of each of a dispersion of a colorant and / or a dispersion of a release agent and a charge control agent, A method of performing the second step after mixing.
-Using a resin solution comprising a polyester resin and a release agent, fine particles are produced in the first step described above, and a colorant dispersion or further a charge control agent dispersion is mixed to perform the second step. Method.

Various dispersions such as a colorant dispersion, a charge control agent dispersion, and a release agent dispersion used here can be obtained as follows. For example, nonionic surfactants represented by polyoxyethylene alkylphenyl ethers, anionic surfactants represented by alkylbenzene sulfonates, alkyl sulfate esters, etc., or quaternary ammonium salts. It can be prepared by a mechanical pulverization method using a medium by adding it to water with a cationic surfactant represented by
Alternatively, instead of the surfactant, a self-water dispersible polyester resin can be used to prepare a dispersion by the same dispersing means in the presence of a basic neutralizing agent. The colorant, release agent, and charge control agent used here may be those previously melt-kneaded with a polyester resin. In this case, when the resin is adsorbed, the degree to which various materials are exposed on the particle surface is alleviated, and preferable characteristics are provided in charging characteristics and development characteristics.

In order to keep the frictional charging performance good, it is effective to prevent the colorant and the like from being exposed on the surface of the toner particles, that is, to have a toner structure in which the colorant and the like are included in the toner particles. It is considered that the deterioration of the chargeability accompanying the reduction in the particle size of the toner is caused by the exposure of a part of other additives such as a colorant and wax contained on the toner particle surface.
That is, even when the content of the colorant and the like is the same, the surface area of the toner particle is increased by reducing the particle size, and the ratio of the colorant and wax exposed on the surface of the toner particle is increased. As a result, the frictional charging performance of the toner particles changes greatly, making it difficult to obtain an appropriate chargeability.

  The toner particles produced according to the present invention desirably have a colorant, wax, or the like encapsulated in a binder resin, and a good printed image can be obtained by having such an encapsulated structure. In order to positively encapsulate the colorant and release agent, the fine particles are produced in the first step using the resin solution comprising the polyester resin and the colorant, or further the release agent and charge control agent. Then, using the method of performing the second step, or using a resin solution comprising a polyester resin and a colorant, or further a mold release agent, the fine particles are produced in the first step, and then the charge control agent dispersion is mixed. It is preferable to perform the method of performing the second step.

The fine particle aggregate obtained in the second step is preferably spherical, and the average circularity is preferably 0.96 or more. The shape of the coalesced particles obtained in the coalescing step is the length of the circumference of the circle corresponding to the projected area of the particle image observed by a particle image analyzer (flow type particle image analyzer FPIA-1000 manufactured by Sysmex), etc. The ratio of the peripheral length of the projected image of the particles is defined as the average circularity.
When the average circularity is 0.96 or more, the shape is substantially spherical or spherical, the powder flowability and transfer efficiency are good, and when fine particles are separated from the dispersion by the method of the present invention. In addition, the separation efficiency is increased.

  The dispersion of particle aggregates obtained in the second step is desolvated in the third step to remove the organic solvent from the slurry.

Next, in the fourth step, the powder obtained by dispersing the particles in the aqueous medium obtained in the third step is classified in a liquid and then dehydrated.
FIG. 1 is a diagram illustrating a method for performing classification and dehydration according to the present invention. 1A is a diagram for explaining a state in which centrifugal force is applied by rotation, FIG. 1B is a diagram for explaining a state in which the rotation is stopped, and FIG. 1C remains. It is a figure explaining the state which removed the dispersion liquid, and all are sectional drawings.
The classifying and dehydrating apparatus 1A of the present invention has a non-porous cylindrical tank 3A having a rotation axis in the vertical direction in the exterior body 2A, injecting a dispersion into the cylindrical tank 3A, and centrifuging by the driving device 4A. When a force is applied to rotate, as shown in FIG. 1 (A), the non-porous wall surface of the cylindrical tank 3A has a particle layer 5A in which particles adhere to the cake, and the inner side of the cylindrical tank 3A has a particle shape. Dispersion layer 6A in which the content of particles is reduced due to adhesion to the inner wall surface is formed.
After the rotation of the cylindrical tank 3A is stopped as shown in FIG. 1 (B) to remove the residual dispersion 7A at the bottom of the cylindrical tank 3A, the cake is placed on the inner wall surface of the cylindrical tank 3A as shown in FIG. 1 (C). The particle layer 5A adhering to the shape can be peeled off and dried to produce toner particles. In addition, the removal method of a dispersion liquid may be removed after rotation stops, and you may remove as a supernatant liquid by skimming during rotation.

Moreover, after peeling off the particle layer 5A adhering to the cake shape adhering to the inner wall surface of the cylindrical tank 3A shown in FIG. 1 (C), an aqueous medium such as water is added to prepare a dispersion, and then the cylindrical tank 3A Rotating and attaching the particles to the inner wall surface of the cylindrical tank 3A, and then repeating the process of removing the dispersion liquid inside the cylindrical tank to remove fine particles and classify and form the particles. Used drug can be removed.
Thus, the step of adding an aqueous medium such as water to the particle layer adhering to the cake to prepare a dispersion again and classifying using a centrifuge is preferably repeated 2 to 7 times.

  In the present invention, it is preferable to apply a centrifugal force of 500 to 900G to the dispersion by rotation of the cylindrical tank 3A. When the dispersion is smaller than 500G, a particle layer is formed from the dispersion on the inner wall surface of the cylindrical tank 3A. Becomes insufficient, and the recovery rate of particles from the dispersion decreases. On the other hand, if the particle size is larger than 900G, fine powder particles contained in the dispersion are strongly taken into the particle layer 5A on the inner wall surface of the cylindrical tank 3A, so that the fine powder particles are not sufficiently classified. When the remaining dispersion is discharged, particles of 2.5 μm or less are not sufficiently removed.

  Further, the time for applying the centrifugal force of 500 to 900G is preferably 5 to 30 minutes, and when it is shorter than 5 minutes, the formation of the particle layer 5A from the dispersion on the inner wall surface of the cylindrical tank 3A is not possible. It becomes sufficient, and the recovery rate of the particles from the dispersion decreases. On the other hand, if it is longer than 30 minutes, the fine powder particles contained in the dispersion are strongly taken into the particle layer 5A on the inner wall surface of the cylindrical tank 3A, so that the fine powder particles are not classified. When the remaining dispersion is discharged, particles of 2.5 μm or less are not sufficiently removed.

Toner mother particles can be obtained by drying the cake of colored resin particles obtained by classification as described above. In this step, by applying heat energy, moisture and residual volatile components are removed to form toner mother particles. For this reason, the higher the drying temperature is, the more efficient, but the fusion of the toner base particles occurs above the glass transition temperature Tg of the resin. Therefore, the inside of the system is preferably performed at a temperature below the glass transition temperature Tg. Further, it is preferable from the viewpoint of the toner properties that the residual moisture content is less than 0.5%.
Examples of the drying include a method of drying under normal pressure or reduced pressure, a method of freeze-drying, and a method of simultaneously separating and drying toner particles from an aqueous medium using a spray dryer or the like. In particular, a method in which powder is stirred and dried under reduced pressure while heating at a temperature at which toner particles are not thermally fused or agglomerated, or an air-flow dryer (Seishin) that is instantly dried using a heated and dried air stream. A method using an enterprise flash jet dryer or the like is efficient and preferable.

  In the present invention, the particle size distribution of the toner is preferably 50% volume particle size / 50% number particle size of 1.25 or less as measured with a Beckman Coulter Multisizer 3 (aperture tube diameter: 50 μm). Preferably it is 1.20 or less. It is preferable that it is 1.25 or less because good images can be easily obtained. Moreover, GSD is preferably 1.30 or less, and more preferably 1.25 or less. The GSD is a value obtained by the square root of (16% volume particle size / 84% volume particle size) as measured by the Multisizer 3 manufactured by Coulter. The smaller the GSD value, the sharper the particle size distribution and the better the image.

As the toner obtained by the method of the present invention, when the volume average particle diameter is a toner having a number mode diameter of 3 to 6 μm, the effect of classification in liquid is high. Further, if the number mode diameter is larger than 6 μm, the classification effect is greatly reduced even if the frequency of 2.5 μm or less, which is less frequent, is classified, and if the toner smaller than 3 μm is classified by 2.5 μm, the yield is lowered and industrially reduced. Not realistic.
Further, if there are too many particles remaining in the dispersion after adhering to the inner wall surface of the cylindrical tank, the classification accuracy is lowered and the particle distribution is also widened. Therefore, when the number mode diameter is 3 μm or more and 6 μm or less, the particle size distribution can be classified so as to be the smallest.

  The polyester resin used in the present invention is synthesized by dehydration condensation of a polybasic acid and a polyhydric alcohol.

  Polybasic acids include terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid and other aromatic carboxylic acids; maleic anhydride, fumaric acid, succinic acid, alkenyl succinic anhydride, Aliphatic carboxylic acids such as adipic acid; and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid. These polybasic acids can be used alone or in combination of two or more. Of these polybasic acids, aromatic carboxylic acids are preferably used.

  Examples of the polyhydric alcohol include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, glycerin, trimethylolpropane, and pentaerythritol; cyclohexanediol, cyclohexanedi Examples thereof include alicyclic diols such as methanol and hydrogenated bisphenol A; aromatic diols such as bisphenol A ethylene oxide adduct and bisphenol A propylene oxide adduct. These polyhydric alcohols can be used alone or in combination of two or more. Among these polyhydric alcohols, aromatic diols and alicyclic diols are preferable, and aromatic diols are more preferable.

  In addition, monocarboxylic acid and / or monoalcohol is further added to the polyester resin obtained by polycondensation of polycarboxylic acid and polyhydric alcohol to esterify the hydroxyl group and / or carboxyl group at the polymerization terminal. The acid value of the polyester resin can be adjusted. Examples of the monocarboxylic acid used for such a purpose include acetic acid, acetic anhydride, benzoic acid, trichloroacetic acid, trifluoroacetic acid, propionic anhydride, and the like. Examples of the monoalcohol include methanol, ethanol, propanol, octanol, 2-ethylhexanol, trifluoroethanol, trichloroethanol, hexafluoroisopropanol, and phenol.

  The polyester resin can be produced by subjecting the polyhydric alcohol and the polyvalent carboxylic acid to a condensation reaction. For example, the above polyhydric alcohol and polyvalent carboxylic acid are mixed in a reaction vessel equipped with a thermometer, a stirrer, and a flow-down condenser, and heated at 150 to 250 ° C. in an atmosphere that does not adversely affect the reaction such as nitrogen. Then, the low-molecular compound produced as a by-product is continuously removed from the reaction system, and when the desired physical property value is reached, the reaction is stopped and cooled to obtain the desired reactant.

  Such a polyester resin can be synthesized by adding a catalyst. Examples of the esterification catalyst used include organic metals such as dibutyltin dilaurate and dibutyltin oxide, and metal alkoxides such as tetrabutyl titanate. Further, when the carboxylic acid component to be used is a lower alkyl ester, a transesterification catalyst can be used. Examples of the transesterification catalyst include metal acetates such as zinc acetate, lead acetate, and magnesium acetate; metal oxides such as zinc oxide and antimony oxide; metal alkoxides such as tetrabutyl titanate, and the like. About the addition amount of a catalyst, it is preferable to set it as the range of 0.01-1 mass% with respect to the total amount of a raw material.

  In such a polycondensation reaction, in order to produce a branched or crosslinked polyester resin in particular, a polybasic acid having 3 or more carboxyl groups in one molecule or an anhydride thereof, and 3 in one molecule. At least one of the above polyhydric alcohols having a hydroxyl group may be used as a raw material.

  The toner of the present invention has a flow softening temperature (Tf1 / 2) of 90 ° C. to 140 ° C. and a glass transition temperature (Tg) in the range of 40 ° C. to 70 ° C. The flow softening temperature (Tf1 / 2) is applied by applying a nozzle diameter of 1.0 mm × 1.0 mm and a pressure of 0.98 MPa per minute using a flow characteristic evaluation apparatus (Shimadzu Corporation flow tester CFT-500). It is a value measured at a heating rate of 6 ° C. The glass transition temperature Tg is a value measured at a rate of temperature increase of 10 ° C. per minute by a second run method using a differential scanning calorimeter (DSC-220C manufactured by Seiko Instruments Inc.).

  The binder resin preferably contains a highly viscous crosslinked polyester resin and a low viscosity branched or linear polyester resin. That is, in the polyester resin of the present invention, the binder resin may be composed of one kind of polyester resin, but generally a crosslinked polyester resin having a high molecular weight and high viscosity, that is, a crosslinked polyester resin, and a low molecular weight. It is practical and preferable to use a blended with a branched or linear polyester resin that is low in viscosity in order to obtain a good fixing start temperature and hot offset resistance. . When blended and used, the flow tester value of the blended resin may be in the above numerical range. In the present invention, the crosslinked polyester resin indicates a resin having a component insoluble in tetrahydrofuran, and the branched or linear polyester resin indicates a resin that has no gel content and dissolves in tetrahydrofuran as measured by the gel content.

  In the present invention, a plurality of polyester resins having different melt viscosities can be used as the binder resin. For example, when a mixture of a low-viscosity branched or linear polyester resin and a high-viscosity cross-linked polyester resin is used, It is more preferable to use a mixture of a branched or linear polyester resin A and a crosslinked or branched polyester resin B under the conditions shown below. At this time, the melt viscosity and blending amount of Resin A and Resin B are appropriately adjusted so that the flow tester value of the blended resin falls within the above numerical range.

That is, the polyester resin A has a T1 / 2 temperature by a flow tester of 80 ° C. or more and less than 120 ° C., a branched or linear polyester resin having a glass transition temperature Tg of 40 ° C. to 70 ° C., and a polyester resin B. Cross-linked or branched polyester resin having a T1 / 2 temperature of 120 ° C. or higher and 210 ° C. or lower with a flow tester and a glass transition temperature Tg of 50 to 75 ° C., and the mass of these polyester resin A and polyester resin B The ratio is
A / B = 20/80 to 80/20,
Further, when T1 / 2 temperatures are T1 / 2 A and T1 / 2 B, respectively,
20 ° C. <T1 / 2 (B) −T1 / 2 (A) <100 ° C.
Those having the relationship are preferably used.

Considering each temperature characteristic by the flow tester, the melting temperature T1 / 2A by the 1/2 method of the resin (A) is an index for imparting sharp melt property and low temperature fixing property. A range of 115 ° C is more preferable, and a range of 90 to 110 ° C is particularly preferable.

  Resin A specified by these performances has a low softening temperature, and in the fixing process using a heat roll, it melts sufficiently even if the applied heat energy decreases due to the lowering of the heat roll or the increase in the process speed. Excellent performance in cold offset resistance and low-temperature fixability.

  If the melting temperature T1 / 2B and the outflow end temperature TendB of the resin B 1/2 method are both too low, hot offset is likely to occur, and if too high, the particle size distribution during particle formation deteriorates. Therefore, T1 / 2 (B) is more preferably 125 ° C to 210 ° C, and particularly preferably 130 ° C to 200 ° C.

  Resin B defined by these performances has a strong rubber elasticity tendency and a high melt viscosity, so that the internal cohesive force of the melted toner layer is maintained even during heating and melting in the fixing process, and hot offset hardly occurs. In addition, it exhibits excellent friction resistance due to its toughness even after fixing.

  By blending the resin A and the resin B at a predetermined blending ratio, it is possible to provide a toner that sufficiently satisfies offset resistance performance and low-temperature fixing performance in a wide temperature range.

  When the mass ratio A / B between the resin A and the resin B is too small, the fixing property is affected. When the mass ratio A / B is too large, the offset resistance is affected. Therefore, it is 20/80 to 80/20. Is preferable, and it is still more preferable that it is 30 / 70-70 / 30.

  Further, when the melting temperatures of the resin A and the resin B by the 1/2 method are T1 / 2A and T1 / 2B, respectively, from the viewpoint of achieving both low-temperature fixability and offset resistance, In order to facilitate uniform mixing without causing problems resulting from the difference, the range of T1 / 2B-T1 / 2A is more preferably higher than 20 ° C and lower than 90 ° C, more preferably higher than 20 and lower than 80 ° C. It is particularly preferred.

In the present invention, the glass transition temperature (Tg) in the present invention is a value obtained by measuring at a rate of temperature increase of 10 ° C. per minute by the second run method using a differential scanning calorimeter (DSC-50) manufactured by Shimadzu Corporation. It is.

When the Tg of the polyester resin (A) is less than 40 ° C. or the Tg of the polyester resin (B) is less than 50 ° C., the resulting toner is blocked during storage or in a developing machine (toner particles are aggregated into a lump. This phenomenon is not preferable. On the other hand, if the Tg of the polyester resin (A) exceeds 70 ° C., or if the Tg of the polyester resin (B) exceeds 75 ° C., the toner fixing temperature increases, which is not preferable. As described above, by using the polyester resin (A) and the polyester resin (B) having the above relationship as the polyester resin as the binder resin, the obtained toner has better fixability, which is preferable. .

  Furthermore, as a binder resin composed of a polyester resin, a molecular weight measurement by a gel permeation chromatography (GPC) method in which tetrahydrofuran (THF) is soluble has a mass average molecular weight of 30,000 or more, preferably 37,000 or more, Weight-average molecular weight (Mw) / number-average molecular weight (Mn) is 12 or more, preferably 15 or more, and the area ratio of components having a molecular weight of 600,000 or more is 0.3% or more, preferably 0.5% or more, and molecular weight 1 In order to obtain good fixability, it is preferable that the area ratio of components of 10,000 or less is 20 to 80%, preferably 30 to 70%. When blending a plurality of resins, the GPC measurement result of the final resin mixture may be within the above numerical range.

  In the polyester resin used in the production method of the present invention, a high molecular weight component having a molecular weight of 600,000 or more has a function of ensuring hot offset resistance. On the other hand, a low molecular weight component having a molecular weight of 10,000 or less is effective for lowering the melt viscosity of the resin, manifesting a sharp melt property and lowering the fixing start temperature, and may contain a resin component having a molecular weight of 10,000 or less. preferable. In order to obtain good thermal characteristics such as low-temperature fixing, hot offset resistance, and transparency in the oilless fixing method, it is preferable that the binder resin has such a broad molecular weight distribution.

  Here, the molecular weight of the THF-soluble component of the binder resin was determined by filtering the THF-soluble matter with a 0.2 μm filter, and then using Tosoh's GPC / HLC-8120 and Tosoh's column “TSKgelSuperHM-M” (15 cm). The molecular weight was calculated by using three, measuring with a THF solvent (flow rate 0.6 ml / min, temperature 40 ° C.), and using a molecular weight calibration curve prepared with a monodisperse polystyrene standard sample.

In addition, the acid value of the polyester resin (mg number of KOH necessary to neutralize 1 g of resin) is easy to obtain the molecular weight distribution as described above, easy to ensure the granulation of fine particles by emulsification dispersion, The range of 1 to 20 mgKOH / g is preferable because it is easy to maintain the environmental stability (chargeability stability when temperature and humidity change) of the obtained toner.
As mentioned above, the acid value of the polyester resin is not limited to the addition of monocarboxylic acid and / or monoalcohol to the polyester resin obtained by condensation polymerization of polyvalent carboxylic acid and polyhydric alcohol. It can adjust by controlling the carboxyl group of the terminal of polyester with the compounding ratio and reaction rate of a polybasic acid of this, and a polyhydric alcohol. Or what has a carboxyl group in the principal chain of polyester can be formed by using trimellitic anhydride as a polybasic acid component.

  A release agent can be used in the toner of the present invention. In this case, the release agent is selected from the group of hydrocarbon waxes such as polypropylene wax, polyethylene wax, and Fischer-Tropsch wax, and natural ester waxes such as synthetic ester wax, carnauba wax, and rice wax. The mold release agent used is used. Of these, natural ester waxes such as carnauba wax and rice wax, and synthetic ester waxes obtained from polyhydric alcohols and long-chain monocarboxylic acids are preferably used. Examples of the synthetic ester wax include WEP-5 manufactured by NOF Corporation. Further, if the content of the release agent is less than 1% by mass, the releasability tends to be insufficient, and if it exceeds 40% by mass, the wax tends to be exposed on the surface of the toner particles, and the chargeability and storage stability are improved. Since it falls easily, the inside of the range of 1-40 mass% is preferable.

  A charge control agent can be blended in the toner of the present invention. The positively chargeable charge control agent is not particularly limited, and nigrosine dyes, quaternary ammonium compounds, onium compounds, triphenylmethane compounds and the like known for toners can be used. In addition, basic group-containing compounds such as amino groups, imino groups, and N-heterocycles, such as tertiary amino group-containing styrene acrylic resins, are also effective as a positively chargeable charge control agent. As a control agent, it can be used alone or in combination with the positively chargeable charge control agent. Depending on the application, a small amount of a negative charge control agent such as an azo dye metal complex or a salicylic acid derivative metal complex salt may be used in combination with these positively chargeable charge control agents. In addition, as the negatively chargeable charge control agent, heavy metals such as trimethylethane dyes, salicylic acid metal complexes, benzylic acid metal complexes, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes, etc. Examples thereof include acidic dyes, calixarene-type phenol condensates, cyclic polysaccharides, resins containing carboxyl groups and / or sulfonyl groups, and the like.

  The content of the charge control agent is preferably 0.01 to 10% by mass. It is especially preferable that it is 0.1-6 mass%.

  Examples of the colorant used in the toner of the present invention include black pigments such as carbon black, cyanine black, aniline black, ferrite, and magnetite. Moreover, what mix | blended the following chromatic pigment so that it might become black can also be used.

  Examples of yellow pigments include yellow iron oxide, ocher, titanium yellow, naphthol yellow S, Hansa Yellow 10G, Hansa Yellow 5G, Hansa Yellow G, Hansa Yellow GR, Hansa Yellow A, Hansa Yellow RN, Hansa Yellow R, Pigment Yellow L, Benzidine Yellow, Benzidine Yellow G, Benzidine Yellow GR, Permanent Yellow NCG, Vulcan First Yellow 5G, Vulcan First Yellow R, Quinoline Yellow Lake, Anslagen Yellow 6GL, Permanent Yellow FGL, Permanent Yellow H10G, Permanent Yellow HR, Anthrapyrimidine Yellow, Other isoindolinone yellow, chromophthal yellow, Novo Palm Yellow H2G, condensed azo yellow, nickel azo yellow, Azomethine yellow, and the like.

  Examples of red pigments include molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, indanthrene brilliant orange GK, benzidine orange G, permanent red 4R, permanent red BL, permanent red F5RK, and resol red. , Pyrazolone red, watching red, lake red C, lake red D, brilliant carmine 6B, brilliant carmine 3B, rhodamine lake B, alizarin lake, permanent carmine FBB, verinone orange, isoindolinone orange, anthanthrone orange, pyranthrone orange , Quinacridone red, quinacridone magenta, quinacridone scarlet, perylene red, etc. And the like.

  Examples of blue pigments include cobalt blue, cerulean blue, alkaline blue rake, peacock blue rake, fanatone blue 6G, Victoria blue rake, metal-free phthalocyanine blue, copper phthalocyanine blue, first sky blue, indanthrene blue RS, and indanthrene. Blue BC, Indico etc. are mentioned.

  The amount of these colorants used is preferably in the range of 1 to 50 parts by weight, particularly preferably in the range of 2 to 15 parts by weight, per 100 parts by weight of the binder resin.

  The dried toner particles can be used as a developer as they are, but external additives such as inorganic oxide fine particles and organic polymer fine particles known as toner external additives can be added to the toner particle surfaces. preferable. Hydrophobic silica, inorganic fine particles such as titanium oxide, or organic fine particles are externally added to toner particles to improve physical properties such as fluidity and chargeability when used as a dry developer by electrostatic printing. effective.

In addition, by adding silicone oil as an external additive to the toner of the present invention, the scattering of the toner can be suppressed, and the scattering of the fine powder can be further reduced in the toner having a small amount of fine powder.
Examples of the silicone oil include dimethyl silicone oil having a kinematic viscosity at 25 ° C. of 50 to 500 mm ² / s.
Silicone oil can be prepared by adding to the toner and stirring at a peripheral speed of 10 to 60 m / sec at the tip of the blade regardless of the scale.

Further, to the toner of the present invention, alumina fine particles having a phase angle (θ) in an AC frequency range of 1 kHz to 10 kHz in an AC impedance method of 80 ° or less, that is, | 80 ° | By doing so, the scattering of the toner can be suppressed, and the scattering of the fine powder can be further reduced in the toner having a small proportion of the fine powder.
Next, the AC impedance method for alumina fine particles will be described.
In general, the conductivity is generally measured quantitatively as the conductivity using an ampere meter. However, when measuring with a powder of alumina fine particles or the like sandwiched between electrodes, it is used as a resistance component. Are considered to be derived from (1) particle bulk, (2) particle-particle contact interface (grain boundary), (3) electrode-particle sample interface resistance, etc. With direct current, these resistance components cannot be distinguished. For this reason, it has been proposed to measure the impedance related to the bulk resistance of particles using an alternating current impedance method using alternating current instead of direct current, but in the present invention, in the state where an AC electric field is applied. The phase angle (θ) for each AC frequency obtained by measurement using the AC impedance method is used as an indicator of charge leakage (conductivity) in the alumina fine particles.

  The alumina fine particles of the present invention have a phase angle (θ) of | 80 ° | or less in an AC frequency range of 1 kHz to 10 kHz in the AC impedance method, but the phase angle (θ) exceeds | 80 ° | When approaching 90 ° |, scattering and fogging from the development gap occur, which is not preferable. A shift of the phase angle (θ) of | 90 ° | indicates that the movement of charges in the alumina fine particles cannot follow the change of the AC frequency, and if the phase angle (θ) is 0 °, the AC frequency It can be in a state in which the movement of charges in the alumina fine particles follows the change. As for the alumina fine particles, the phase angle (θ) in the AC frequency 1 kHz to 10 kHz section is considered to be about | 40 ° |

  The AC frequency is specified as the 1 kHz to 10 kHz section when the AC component of the developing electric field applied between the photosensitive member and the developing roller is inversely proportional to the size of the gap between the photosensitive member and the developing roller and the frequency is small. This is because it is preferable to set a large frequency and a small frequency when the gap is large. For example, when using a toner having a small average volume particle size of about 2 μm, it is preferable to set the gap to be small so that the AC frequency is about 10 kHz. In addition, when using toner having a large average volume particle size of about 12 μm, it is preferable to set the gap amount large and the AC frequency to about 1 kHz.

The alumina fine particles are prepared by various production methods, and those having a phase angle (θ) of | 80 ° | or less in an AC frequency of 1 kHz to 10 kHz are obtained by pyrolyzing ammonium dowsonite, for example. Examples thereof include those produced by the production methods described in JP-A-63-100017, JP-A-58-26029, and JP-A-51-139810, and the purity of alumina is 99.99% or more. BET specific surface area of 100m ² / g~300m ² / g, as number average particle size is of 5 nm to 20 nm. As a commercially available product, Taimyk Chemical Co., Ltd. Tymicron TM-100: Al ₂ O ₃ , θ-alumina phase as the main phase, primary particle size 14 nm, BET specific surface area 132 m ² / g, Taimei Chemicals Tymicron TM-300 : Al ₂ O ₃ , γ-alumina phase as the main phase, primary particle size 7 nm, BET specific surface area 225 m ² / g is exemplified.

  The phase angle of the alumina fine particles (Tymicron TM-100) measured by the AC impedance method is about | 65 ° | at 1 kHz and continuously increases to | 79 ° | at 10 kHz. The phase angle of the alumina fine particles (Tymicron TM-300) is about | 43 ° | at 1 kHz and continuously increases to | 70 ° | at 10 kHz.

Further, there are exemplified alumina fine particles obtained by evaporating metal aluminum with DC arc plasma and oxidizing the vapor with alumina fine particles prepared by the production method described in JP-A-2002-253953. The alumina fine particles, alumina purity of at least 99.9%, BET specific surface area of 20m ² / g~80m ² / g, as number average particle size is of 20 nm to 100 nm. As a commercial product, NanoTek Al ₂ O ₃ : γ-alumina phase manufactured by CI Kasei Co., Ltd. is a crystalline spherical fine particle containing a small amount of α-alumina phase, a primary particle size of 30 nm, and a BET specific surface area of 49.3 m. ² / g is exemplified.

  The phase angle of commercially available alumina fine particles (NanoTek) is approximately | 58 ° | at 1 kHz, and | 48 ° | at 10 kHz, and gradually decreases from 1 kHz to 10 kHz. In the alumina fine particles having a phase angle (θ) of | 80 ° | or less in an AC frequency range of 1 kHz to 10 kHz in the AC impedance method, scattering from the development gap and fogging are extremely small.

On the other hand, the phase angle of alumina fine particles (manufactured by Nippon Aerosil Co., Ltd .: C805, particle size 13 nm), which are generally conductive fine particles, is approximately | 86 ° | at 1 kHz and | 88 ° at 10 kHz. The phase angle of titania (STT30S manufactured by Titanium Industry Co., Ltd., particle size 20-50 nm, BET specific surface area 135-155 m ² / g) is about | 85 ° | at 1 kHz. At 10 kHz, it is about | 88 ° |, which is a value close to about 90 °. In the alumina fine particles having a phase angle (θ) exceeding | 80 ° | in the AC frequency range of 1 kHz to 10 kHz in the AC impedance method, an undesirable amount of scattering and fogging from the development gap occurred.

The phase angle (θ) in the AC impedance method was measured using a dielectric measurement system (126096W manufactured by Solartron, UK) under the following conditions.
Sample holder for room temperature solid 12962A
Sample shape Tablet shape of φ11mm x 1mm (pressing pressure 2ton)
Setting voltage applied to the sample holder 0.1V with both sides of the sample sandwiched by metal aluminum electrodes via conductive paste
Measurement frequency 1mHz ~ 1MHz

  The alumina fine particles in the present invention exhibit an effect of charge leakage under an AC electric field and have an effect of stabilizing the frictional charging of the toner. In addition, there is an effect of stabilizing the charging performance of the photosensitive member by refreshing the surface of the photosensitive member by the polishing action of the alumina fine particles. Further, when the developing device can replenish the toner, it is newly added in addition to the residual toner. In a toner replenishment type developing device that is toner to be replenished, or if the developing device cannot replenish toner, in a toner exhaustion type developing device that is newly filled toner in addition to residual toner, toner It is possible to reduce supply fog and to reduce residual memory generated due to the free external additive remaining on the photoreceptor.

  The alumina fine particles of the present invention are externally added at a ratio of 0.2 parts by mass to 5.0 parts by mass, preferably 0.5 parts by mass to 2.0 parts by mass with respect to 100 parts by mass of the toner base particles. Good. If the amount of treatment with respect to the toner base particles is larger than this, there is a problem that the charge leakage action is excessively generated or free external additives are generated, and if it is less, the desired polishing effect cannot be obtained.

Next, an image forming apparatus using the toner of the present invention will be described.
FIG. 2 is a diagram illustrating an example of an image forming apparatus according to the present invention.
The image forming apparatus 1 is an apparatus in which image forming units are arranged in a tandem manner, and includes a housing 2 and a paper discharge tray 3 formed on the housing 2. The housing 2 includes a power supply unit 4, a control unit 5, An image forming unit 6, a fixing unit 7, and a paper feeding unit 8 are provided.

The image forming unit 6 is a single color image forming unit Y (for yellow), M (for magenta), C (for cyan), K (for black) that forms a plurality of (four in this embodiment) different color images. Each of the monochromatic image forming units Y, M, C, and K includes a photosensitive member 61 formed of a photosensitive member on which an organic photosensitive layer or an inorganic photosensitive layer is formed, and a developer disposed around the photosensitive member 61. Means 100 and exposure means 200 are provided.
The respective color photoreceptors 61Y, 61M, 61C, 61K of the single-color image forming units Y, M, C, K are in contact with the transfer belt 62, and the transfer rollers 62Y, 62M, 62C, 62K are interposed via the transfer belt. Is arranged. Each of these transfer rollers is electrically connected to transfer voltage supply means (not shown). Then, by applying a transfer voltage to the transfer roller, the toner image formed on the surface of each photoconductor 61 is sequentially primary transferred onto the surface of the transfer belt 62 to form a color image.

  The transfer belt 62 is driven to circulate in the direction of the arrow by the drive roller 63 and also serves as a backup roller for the transfer roller 64. A rubber layer having a thickness of about 3 mm and a volume resistivity of 1000 kΩ · cm or less is formed on the peripheral surface of the drive roller 63, and is supplied via the transfer roller 64 by being grounded via a metal shaft. The transfer voltage conduction path is made. By providing the driving roller 63 with a rubber layer having high friction and shock absorption, the impact when a recording medium such as paper or an OPC film enters the contact portion between the driving roller 63 and the transfer roller 64 can be prevented. It is difficult to transmit to the transfer belt 62, and deterioration of image quality can be prevented.

Further, the transfer belt 62 is provided with a cleaner portion 66 so as to face the stretching roller 65. The cleaner unit 66 includes waste toner collecting means 68 having a cleaner blade 67. The cleaner blade 67 abuts the tip of the cleaner blade 67 against the stretching roller 65 via the transfer belt 62 to remove foreign matters such as toner and paper dust remaining on the transfer belt after transfer. The foreign matter removed in this way is collected by the waste toner collecting means 68.
Further, the transfer roller 64 is provided so as to be able to come into contact with the transfer belt 62 and is driven by a transfer roller driving mechanism (not shown).

  The paper feed unit 8 includes a paper feed unit having a paper feed cassette 81 that stacks and holds a plurality of paper sheets, and a pickup roller 82 that feeds paper one by one from the paper feed cassette 81. The paper is fed from the paper feed unit by the pickup roller 82 and the paper feed timing is adjusted by the roller pair 83, and then fed to the transfer roller 64 and secondarily transferred. In the present invention, paper feed, paper, and the like each mean a recording medium capable of forming an image including not only paper but also an OPC film or the like.

The fixing unit 7 includes a heating roller 71 that includes a heating element such as a halogen heater and is rotatable, and a backup roller 72 that is disposed to face the heating roller 71. The transferred toner image is an image at a predetermined temperature. Heat-fixed.
The paper thus subjected to the fixing process is conveyed to a paper discharge tray 3 provided on the upper surface of the housing 2.
In the above description, an example in which the image forming units are arranged in a tandem manner has been described. However, an image forming apparatus of a type in which four color developing units are arranged around one photoconductor and sequentially developed may be used.

FIG. 3 is a diagram for explaining the image forming mechanism of the present invention, FIG. 3 (A) is a diagram for explaining the image forming unit explained in FIG. 2 in an enlarged manner, and FIG. It is a figure explaining a process. 4A and 4B are diagrams for explaining the developing means of the present invention, FIG. 4A is a side view, and FIG. 4B is an enlarged cross-sectional view of one end of the developing roll.
The image forming unit 6 includes a photoconductor 61 and a developing unit 100 disposed around the photoconductor 61.

  The developing means 100 includes a developing roller 101 that conveys toner to the photosensitive member 61, a supply roller 102 that is pressed against the developing roller 101 to supply toner, and a regulation that regulates the toner that is pressed against the developing roller 101 and conveyed to the photosensitive member 61. A blade 103 and toner collecting means 104 for collecting toner remaining on the photosensitive member 61 after primary transfer are provided. In addition, a charging unit 105 and a line head type exposure unit 200 are provided in the vicinity of the photoreceptor 61.

  The developing unit 100 includes a developing roller 101 that transports toner to the photosensitive member 61, a supply roller 102 that is pressed against the developing roller 101 and supplies toner, and is provided in a portion excluding the toner transporting portion 101 </ b> T at the center of the developing roller 101. Further, spacers 106A and 106B that are concentric with the developing roller 101 and have a uniform thickness are provided, and a predetermined developing gap G is formed by rotating the surfaces of the spacers 106A and 106B in contact with the photosensitive member 61. The

  The development gap G is adjusted to a desired size by appropriately selecting the thicknesses of the spacers 106A and 106B. The photosensitive member 61 is set to rotate clockwise, and the developing roller 101 and the supply roller 6 are both rotated counterclockwise. The peripheral speed of the photoconductor 61 and the peripheral speed of the spacers 106A and 106B on the developing roller 101 are set to be the same or substantially the same. Thereby, non-contact jumping development of a non-magnetic one-component developer using toner which is a non-magnetic one-component developer can be realized.

For the developing roller 101, a member having small stress shrinkage or thermal shrinkage, for example, a metal roller such as iron or a resin such as urethane is used. On the other hand, the spacers 106A and 106B provided on the developing roller 101 are elastic and have higher hygroscopicity than the developing roller 101. When the humidity increases, the spacers 106A and 106B swell and become larger in volume. It is preferable to use a substance that increases the distance between the photosensitive member and the photosensitive member, that is, the development gap, and is less susceptible to discharge even when the humidity is high, and that can perform the same charge development.
Specifically, polyamides, polyamideimides, acetates, acrylates, rubbers, and the like having a high water absorption rate can be used, and a substance having low conductivity is preferable. Furthermore, it is preferable to join with a non-water-absorbing and insulating pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive or a silicone-based pressure-sensitive adhesive because insulation is maintained even when moisture is absorbed.

In FIG. 4B, the spacers 106A and 106B are fixed by elastic adhesive layers 107 on the surfaces of the portions other than the toner conveying portion at both ends of the developing roller 101 as shown in the sectional view in FIG. be able to. The spacer may be fixed using heat shrinkage of the spacer material in addition to the adhesive layer.
The dimensional change caused by swelling of the spacers 106A and 106B due to moisture absorption is preferably such that the dimensional change in the direction perpendicular to the axis of the developing roller, that is, the thickness direction, is larger than the dimensional change in the horizontal direction, that is, the axial direction and the circumferential direction.
For this purpose, as shown in FIG. 4B, the developing roller 101 has a dimensional change caused by swelling of the spacer 106A in the horizontal direction, and a dimensional change caused by swelling in the vertical direction, that is, in the thickness direction. It is preferable to arrange the horizontal dimension fluctuation preventing unit 108 along the side surface 109 of the spacer 106A in the axial direction of the developing roller. As the horizontal dimension fluctuation preventing unit 108, a material material that has a smaller dimensional change due to moisture absorption than the spacer material can be used.
It is preferable that the horizontal dimension fluctuation preventing portions are provided in both spacers arranged at both ends of the developing roller.

  According to such an image forming apparatus using the developing unit 100, the spacers 106A and 106B fixed to the developing roller 101 are made of a material having higher hygroscopicity than the developing roller 101. When used in a humidity environment, the hygroscopic spacers 106A and 106B swell due to moisture absorption, and the development gap G increases. Thereby, it is possible to prevent a decrease in the discharge start voltage between the developing roller and the photoconductor even in a high humidity environment. Accordingly, even when the image forming apparatus is used under ambient conditions of high temperature and high humidity, a relatively high development voltage can be applied, and the image quality can be improved. In particular, the application of a high development voltage is extremely effective in image formation using a toner having a small particle diameter.

  Further, by fixing the spacers 106A and 106B to the developing roller 101 with the adhesive layer 107 having elasticity, even if the spacers 106A and 106B swell in a high humidity environment, the spacer does not come off from the developing roller 101, and the development The gap G becomes large and the effect of non-contact development can be more reliably exhibited.

  Furthermore, the dimensional change of the spacers 106A and 106B caused by swelling due to moisture absorption is set such that the dimensional change in the vertical direction, that is, the thickness direction is larger than the dimensional change in the horizontal direction, that is, the axial direction and the circumferential direction. The rate of change of the development gap G due to the swelling of 106A and 106B can be effectively increased. Further, by reducing the dimensional change in the horizontal direction in which wrinkles are likely to occur in the spacers 106A and 106B, generation of wrinkles in the spacers 106A and 106B can be suppressed. In particular, by providing the horizontal dimension fluctuation preventing unit 108, it is possible to suppress the dimension change in the axial direction of the spacers 106A and 106B due to swelling, and to increase the rate of change in the dimension in the thickness direction. As a result, the rate of change of the development gap G can be increased more effectively, and wrinkles of the spacers 106A and 106B can be more effectively suppressed.

As in the present invention, when high-resolution image formation is performed using toner with a number mode diameter of 3 μm or more and 6 μm or less and a frequency of 2.5 μm or less, high-precision development gap retention and AC voltage It is preferable that development is performed by applying a development voltage in which is superimposed.
The development gap is adjusted to 20 to 70 μm, and as the development voltage, it is preferable to superimpose a rectangular wave AC voltage of 800 V to 1400 V having a frequency of 4000 to 8000 Hz on a DC voltage of 100 to 400 V.
As described above, it is possible to develop a high-resolution image by using a high-precision development gap by a spacer and a toner having a number mode diameter of 3 μm or more and less than 6 μm.
The present invention will be described below with reference to examples and comparative examples.

Example 1
Manufacture of toner Synthesis of cross-linked polyester resin for binder resin Raw materials such as acid, alcohol component and catalyst of the following composition are put into a 50 liter reaction kettle and reacted at 240 ° C. for 12 hours under a normal pressure nitrogen stream. Went. Thereafter, the pressure was reduced successively and the reaction was continued at 1.33 × 10 ³ Pa. The reaction was followed by the softening point based on ASTM E28-517, and the reaction was terminated when the softening point reached 160 ° C.
Terephthalic acid 3.9 parts by mass Isophthalic acid 9.06 parts by mass Ethylene glycol 2.54 parts by mass Neopentyl glycol 4.26 parts by mass Tetrabutyl titanate 0.1 parts by mass Epicron 830 0.3 parts by mass (Dainippon Ink and Chemicals, Inc. Bisphenol F type epoxy resin, epoxy equivalent 170 (g / eq)
Cardura E 0.1 parts by mass (Shell Japan alkyl glycidyl ester) epoxy equivalent 250 (g / eq)

The obtained polymer was a colorless solid, and had an acid value of 11.0, a glass transition temperature (Tg) of 60 ° C., and a softening point (T1 / 2) of 178 ° C.
In addition, the weight average molecular weight was used in combination with TOS-GEL G5000HXL / G4000HXL / G3000HXL / G2000HXL manufactured by Tosoh as a separation column using a GPC measuring apparatus (HLC-8120GPC manufactured by Tosoh), column temperature: 40 ° C., solvent: tetrahydrofuran, solvent When measured at a concentration of 0.5 mass%, filter: 0.2 μm, flow rate: 1 ml / min and converted using standard polystyrene, the weight average molecular weight was 250,000.

Synthesis of Binder Resin (Linear Polyester Resin) In a 50 liter reaction kettle, raw materials such as acid, alcohol component, catalyst, etc. of the following composition were placed and reacted at 210 ° C. for 12 hours under a normal pressure nitrogen stream. went. Thereafter, the pressure was reduced successively and the reaction was continued at 1.33 × 10 ³ Pa. The reaction was followed by the softening point according to ASTM E28-517, and the reaction was terminated when the softening point reached 87 ° C.
Terephthalic acid 5.31 parts by weight Isophthalic acid 7.97 parts by weight Ethylene glycol 2.6 parts by weight Neopentyl glycol 4.37 parts by weight Tetrabutyl titanate 0.1 part by weight The obtained polymer, that is, a linear polyester resin is It was a colorless solid having an acid value of 10.0, a glass transition temperature (Tg) of 46 ° C, and a softening point (T1 / 2) of 95 ° C.
Further, when the molecular weight was measured in the same manner as the molecular weight measurement of the obtained linear polyester resin, the weight average molecular weight was 5200.

Preparation of Wax Master Dispersion After 30 parts by weight of Carnauba wax (manufactured by Toa Kasei), 70 parts by weight of the previously produced linear polyester resin and 150 parts by weight of methyl ethyl ketone were premixed with a desper, then Starmill LMZ-10 ( A wax master dispersion 1 having a solid content of 40% by mass was prepared. This composition is linear polyester resin / wax / methyl ethyl ketone = 28/12/60.

Preparation of colorant master chip Cyan pigment (Dai Nippon Ink Chemical Co., Ltd. Cyan Pigment: Ket Blue111 CIPigment B-15: 3) 2000 parts by mass, linear polyester resin 2000 parts by mass, ST / AO stirring blade The mixture was put into a 20 L Henschel mixer (made by Mitsui Mine) and stirred for 2 minutes at 698 min ⁻¹ to obtain a mixture. The mixture was melt-kneaded using an open roll continuous extrusion kneader (Mitsui Mine Needex MOS140-800) to prepare a colorant master chip.
Moreover, when the obtained master chip was diluted with a linear polyester resin and methyl ethyl ketone and observed with a 400 times optical microscope for the finely dispersed state of the colorant and the presence or absence of coarse particles, there was no coarse particles and the fine dispersion was uniform. Was. The composition of the master chip was colorant / resin = 50/50 by mass ratio.

Colored resin liquid preparation step 10.8 parts by mass of wax master dispersion, 10.4 parts by mass of colorant master chip, 12 parts by mass of cross-linked polyester resin, 10 parts by mass of linear polyester resin, and 8.65 parts by mass of methyl ethyl ketone The temperature was kept at 40 to 45 ° C., and the mixture was mixed for 2 hours at a stirring speed of 777 min ⁻¹ with a stirrer (Desper blade diameter 230 mm manufactured by Asada Iron Works), and dissolved and dispersed.

Emulsification step Into a 2 m ³ cylindrical reaction vessel equipped with a stirrer (Desper, manufactured by Asada Iron Works), 46.37 parts by mass (solid content 30 parts by mass) of the colored resin solution was charged so that the solid content was 200 kg. Next, 5 parts by mass of 1N aqueous ammonia was added as a basic compound, and after sufficiently stirring at 777 min ⁻¹ , the temperature was adjusted to 35 ° C.
Subsequently, the stirring speed was changed to 1100 min ⁻¹ and 37.25 parts by mass of water was added dropwise at a rate of 1.0 parts by mass / min. The peripheral speed of the stirring blade at this time was 13.2 m / s. As water was added, the viscosity of the system increased, but water was taken into the system at the same time as dropping, and stirring and mixing could be performed uniformly.
In addition, a phase inversion point at which the viscosity sharply decreased when 26 parts by mass of water was added was observed. Furthermore, after adding water, when the slurry was observed with an optical microscope, the resin was dissolved, and a state where the colorant dispersoid and the wax dispersoid were dispersed was observed, but the non-emulsified material was not observed. It was. Since the colorant dispersoid and the wax dispersoid are stably dispersed in the aqueous medium, it is considered that the resin is adsorbed on the surface of the dispersoid. At this time, the state in the system was uniform, and generation of coarse particles due to the addition was not observed.

Combined process After the emulsified suspension obtained in the emulsifying process was transferred to a 2 m ³ reaction vessel equipped with Max Blend blade (registered trademark), the temperature was kept at 25 ° C. while maintaining the stirring speed at 85 min ^−1. Adjusted. Thereafter, the stirring speed was increased to 120 min ⁻¹ , and 12 parts by mass of a 3.5 mass% sodium sulfate aqueous solution was dropped as an electrolyte aqueous solution at a rate of 1 kg / min. Five minutes after the completion of dropping, the stirring speed was lowered to 85 min ⁻¹ and stirring was performed for 5 minutes, and then the stirring speed was lowered to 65 min ⁻¹ and stirring was performed.
When coalescence progressed to 4 μm, the stirring speed was increased to 120 min ⁻¹ and stirring was continued for 30 minutes. Then, 0.1 m ^{3 of} water was added dropwise to stop coalescence, and a coalescence solution was obtained.

Separation process While rotating a basket-type centrifuge equipped with a non-porous basket (T-36 type, manufactured by Tanabe Wiltech Co., Ltd.) at 600 G, supply 0.3 m ³ of the combined liquid obtained in the previous process and supply for 10 minutes. After operating the centrifuge, the dispersion was removed, and the particles stuck to the cake were scraped off. The scraped particles were stirred and mixed with 0.2 m ³ of water, and centrifuged in the same manner as in the above centrifugation step. This centrifugation operation was repeated 5 times.

Drying Step The obtained cake-like particles were dried for 48 hours in a vacuum stirring vessel kept at 30 ° C. The particles contracted slightly by drying, and the number mode diameter of the obtained particles was 3.9 μm.

External Addition Step 100 g of the obtained particles are used as toner base particles, 2 parts by weight of negatively chargeable silica silica fine particles RX200 (Nippon Aerosil average particle size 12 nm, hexamethyldisilazane treatment), negatively chargeable silica silica fine particles RX50 (Nippon Aerosil) Ltd. the average particle diameter of 40 nm, 1.5 parts by mass of hexamethyldisilazane treatment), alumina particles (Taimei chemical Co. TAIMICRON _{TM-100, Al 2 O 3} , as the main phase θ- alumina phase, primary particle size 14nm , BET specific surface area of 132m ² / g) 2 parts by weight was added, the toner 1 was stirred for 3 minutes at 10000 min ^-1 at Waring Co. Waring blender 1 liter type agitator 7012S (circumferential speed 30 m / sec corresponding to the blade) It was.
Further, if necessary, 0.2 mass% of dimethyl silicone oil (KF-96-200CS manufactured by Shin-Etsu Chemical Co., Ltd.) having a kinematic viscosity at 25 ° C. of 200 mm ² / s as a silicone oil is added and similarly 10000 rpm. The toner was prepared by stirring for 1 minute at a blade peripheral speed of 30 m / sec.

Measurement of Particle Size Distribution of Toner The particle size distribution of the obtained toner was measured with a particle image analyzer (Sysmex flow type particle image analyzer FPIA-2100). The measurement range was 0.6 μm to 400 μm, the number mode diameter which is the peak of the number frequency distribution was determined, and the number frequency and volume frequency of 2.5 μm or less were determined.

Measurement of fine particles emitted from image forming apparatus A toner cartridge of a laser printer (Seiko Epson LPS6500) was filled with a test toner and printed. For printing conditions, the bias was adjusted so that the color density OD value on paper was 1.4.
Measurement is based on the RAL-UZ122 “printing function” established by the Federal Institute for Materials Testing, which is stipulated in the basic standard “office equipment (printer, copier, multi-function device) with printing function” for the delivery of the German environmental label. Predetermined printing area ratio in a 2 m ² chamber with a ventilation rate of 4 based on “Test method for determining scattering from hard copy devices in relation to providing environmental labels for office equipment provided” 400 sheets (10 minutes) were continuously printed using 5% standard pattern RAL_UZ122 / RALA00.PDF.
The PM2.5 was measured by measuring the particle size distribution during continuous printing with an ultrafine particle counter (TSI 8220) and integrating the mass of particles having a particle size of 2.5 μm or less as a specific gravity of 1.
The obtained results are shown in Table 1.

Examples 2-4
A toner was prepared in the same manner as in Example 1 except that the centrifugal force and the centrifugation time in the classification process were changed to the conditions shown in Table 1, and the characteristics of the toner were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Examples 1-4
A toner was prepared in the same manner as in Example 1 except that the centrifugal force and the centrifugation time in the classification process were changed to the conditions shown in Table 1, and the characteristics of the toner were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 5
In coalescing step, where advanced coalescence until 4 [mu] m, the stirring rate after the stirring was continued for a an elevated 20 minutes 120min ^-1, circularity by stopping the water 0.1 m ³ dropped coalescence A toner was prepared in the same manner as in Example 1 except that 0.97 toner was prepared, and the characteristics of the toner were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 6
In the coalescence process, when coalescence progresses to 4 μm, the stirring speed is increased to 120 min ⁻¹ and stirring is continued for 10 minutes. Then, 0.1 m ^{3 of} water is dropped to stop the coalescence. A toner was prepared in the same manner as in Example 1 except that 0.96 toner was prepared, and the characteristics of the toner were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 7
0.2% by mass of dimethyl silicone oil (KF-96-200CS manufactured by Shin-Etsu Chemical Co., Ltd.) having a kinematic viscosity at 25 ° C. of 200 mm ² / s as a silicone oil was added to the toner obtained in Example 6. Similarly, the toner was prepared by stirring for 1 minute at 10,000 min ⁻¹ (equivalent to a peripheral speed of the blade of 30 m / sec), and the characteristics of the toner were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 5
In the coalescence process, when coalescence has progressed to 4 μm, the stirring speed is increased to 120 min ⁻¹ and stirring is continued for 5 minutes. Then, 0.1 m ^{3 of} water is added dropwise to stop the coalescence, thereby reducing the circularity. A toner was prepared in the same manner as in Example 1 except that 0.95 toner was prepared, and the characteristics of the toner were evaluated in the same manner as in Example 1. The results are shown in Table 1.
I got.

Comparative Example 6
In the coalescence process, when coalescence progresses to 4 μm, the stirring speed is increased to 120 min ⁻¹ and stirring is continued for 2 minutes. Then, 0.1 m ^{3 of} water is dropped to stop the coalescence. A toner was prepared in the same manner as in Example 1 except that 0.94 toner was prepared, and the characteristics of the toner were evaluated in the same manner as in Example 1. The results are shown in Table 1.
I got.

After depositing the particle layer on the wall surface of the cylindrical tank with the centrifuge having the non-porous cylindrical tank as in the present invention, the remaining dispersion was removed and the particle layer deposited in the cake shape was recovered. In addition, it does not settle down to a fine powder like a perforated centrifugal separation or a filtration-type solid-liquid separation to form a cake, and because fine powder particles can be separated, a fine powder of 2.5 μm or less It becomes possible to obtain particles substantially free of.
The toner of the present invention was significantly less than 25 μg / m ³ , which is a guide value for WHO of PM2.5. As described above, it is possible to provide a toner and an image forming apparatus that can comply with the regulation by PM2.5.

  DESCRIPTION OF SYMBOLS 1A ... Classification dehydration apparatus, 2A ... Exterior body, 3A ... Cylindrical tank, 4A ... Drive apparatus, 5A ... Particle layer, 6A ... Dispersion liquid layer, 7A ... Residual dispersion liquid, 1 ... Image forming apparatus, 2 ... Housing, 3 ... Paper discharge tray, 4 ... power supply unit, 5 ... control unit, 6 ... image forming unit, 61, 61Y, 61M, 61C, 61K ... photoconductor, 61S ... photoconductor surface, 62 ... transfer belt, 63 ... drive roller, 64 DESCRIPTION OF SYMBOLS ... Transfer roller, 65 ... Stretching roller, 66 ... Cleaner part, 67 ... Cleaner blade, 68 ... Waste toner collection means, 7 ... Fixing unit, 71 ... Heating roller, 72 ... Backup roller, 8 ... Paper feed unit, 81 DESCRIPTION OF SYMBOLS ... Paper feeding cassette, 82 ... Pickup roller, 83 ... Roller pair, 100 ... Developing means, 101 ... Developing roller, 102 ... Supply roller, 103 ... Restricting blade, 104 ... Toner recovery Stage, 105 ... charging means, 106, 106 a, 106B ... spacer 107 ... adhesive layer, 108 ... lateral dimension variation preventing portion, G ... development gap, 200 ... exposure means

Claims (10)

  A dispersion liquid in which colored resin particles are dispersed in an aqueous medium is injected into a centrifuge having a non-perforated cylindrical tank on an inner wall surface having a rotation axis in the vertical direction, and the inner wall surface of the cylindrical tank is rotated. A method for producing a toner comprising: separating the colored resin particles adhering to the inner wall surface after discharging the dispersion in the cylindrical tank after the particle component adheres to the surface by centrifugal force.   2. The toner production method according to claim 1, wherein the centrifugal force is 500 to 900 G, and the rotation time is 5 to 30 minutes.   After separating the dispersion liquid in the cylindrical tank, the colored resin particles attached to the inner wall surface are dispersed in an aqueous medium, injected into the centrifuge, and the process according to claim 1 or 2 is repeated. Toner manufacturing method.   4. The toner manufacturing method according to claim 1, wherein the circularity of the colored resin particles is 0.96 or more.   The method for producing a toner according to any one of claims 1 to 4, wherein the number mode diameter of the colored resin particles is 3 µm or more and 6 µm or less.   The colored resin particles are colored resin particles produced by emulsifying a composition containing at least a synthetic resin, a colorant, and a wax in an aqueous medium and adding the electrolyte together. The method for producing a toner according to claim 1, wherein the toner is a toner.   The dispersion liquid in which colored resin particles are dispersed in an aqueous medium is injected into a centrifuge equipped with a cylindrical tank having no opening on the inner wall surface having a rotation axis in the vertical direction, and rotated. After the particle components adhere to the inner wall surface of the cylinder by centrifugal force, the rotation of the cylindrical tank is stopped, and the cylindrical tank is classified by discharging the dispersion liquid in which the ratio of particles having a small particle diameter is increased. A toner obtained by drying colored resin particles adhering to the inner wall surface of the toner.   8. The composition according to claim 7, wherein 0.05 to 2 parts by mass of silicone oil is blended per 100 parts by mass of the colored resin particles after drying the colored resin particles attached to the inner wall surface of the cylindrical tank. toner.   The toner according to claim 7 or 8, comprising alumina fine particles having a phase angle (θ) in an AC frequency range of 1 kHz to 10 kHz in an AC impedance method of | 80 ° | A photosensitive member carrying an electrostatic latent image, and an electrostatic latent image carried on the photosensitive member that is opposed to the photosensitive member in a non-contact state,
The dispersion liquid in which colored resin particles are dispersed in an aqueous medium is injected into a centrifuge equipped with a cylindrical tank having no opening on the inner wall surface having a rotation axis in the vertical direction, and rotated. After the particle component adheres to the inner wall surface of the cylinder by centrifugal force, the rotation of the cylindrical tank is stopped, and the cylinder is classified by discharging the dispersion liquid in which the ratio of particles having a small particle diameter is increased. By the toner that dried colored resin particles adhering to the inner wall surface of the tank,
There is a developing machine for developing by jumping development that causes toner to fly between the developing means held in a non-contact state and the electrostatic latent image carrier and to attach the toner to the electrostatic latent image on the electrostatic latent image carrier. An image forming apparatus.

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