JP4787140B2 - Method for producing toner for electrophotography - Google Patents

Description

  The present invention relates to a method for producing an electrophotographic toner used for image formation for visualizing an electrostatic latent image.

  Recently, there has been a demand for higher image quality for copiers and printers using electrophotography. For example, the diameter of the electrophotographic toner has been reduced in order to increase the resolution of the image, and various improvements have been made, such as making the shape of the electrophotographic toner spherical to ensure high transferability.

Conventionally, as a method for producing an electrophotographic toner, there are a pulverization method and a polymerization method.
In the pulverization method, a colorant, a charge control agent, etc. are melt-kneaded in a thermoplastic resin, the kneaded product is cooled and solidified, and then mechanically pulverized by a pulverizer, and a desired particle size as an electrophotographic toner is determined by a classifier. How to get.
In the polymerization method, a toner main resin is dissolved in a solvent to prepare a toner main resin solution, and a colorant and the like are uniformly dispersed in the resin solution, and then a chemical technique is used in the liquid phase. A method for producing a photographic toner.

The shape of the electrophotographic toner obtained by the above polymerization method is spherical. However, in the obtained toner, a dispersant, a stabilizer and the like used at the time of manufacture are likely to remain on the surface of the toner particle, and the charge amount of the electrophotographic toner is affected by the use environment.
On the other hand, the pulverization method includes a method in which the shape of the electrophotographic toner is made spherical by applying mechanical impact, and a method in which the shape of the electrophotographic toner is made spherical by heating the pulverized material.

  However, in the method of applying a mechanical impact, it is necessary to apply the impact for a long time in order to make the pulverized material, which was originally indeterminate, into a sphere near the perfect circle. Furthermore, there are many problems in terms of production efficiency and electrophotographic toner performance, because the finely divided electrophotographic toner resin fragments adhere to the surface of the electrophotographic toner again.

  Further, in the method of heating the pulverized product, spherical toner can be easily produced, but it is necessary to highly disperse the electrophotographic toner in the gas phase. For example, in Japanese Patent Application Laid-Open No. 59-125740 (Patent Document 1), the pulverized electrophotographic toner is discharged into a swirling hot air, and the electrophotographic toner particles are heated and melted to be spherical. .

  However, the shape of the electrophotographic toner immediately after pulverization is indefinite, and it is difficult to uniformly disperse it in a swirling flow made of hot air, and adjacent electrophotographic toners tend to aggregate. In addition, the agglomerated large particle electrophotographic toner is separated from the swirling flow by centrifugal force, adheres to the wall surface of the apparatus, and accumulates on the wall surface.

JP 59-125740

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when the electrophotographic toner after pulverization having an irregular shape is heated to produce spherical and nearly spherical toner particles, the coalesced particles of the electrophotographic toner It is an object of the present invention to provide a method for producing a spherical or substantially spherical toner for electrophotography efficiently in a short time.

  As a result of extensive research, the present inventor has pulverized an electrophotographic toner obtained by mechanically pulverizing a resin kneaded material obtained by kneading a colorant and a toner main resin into a spherical or substantially spherical shape. It has a mechanism for heating and melting the electrophotographic toner in the gas phase, and comprises a superheated steam generator as the heating means, and the electrophotographic toner is released into the swirling flow of the superheated steam, It was found that the electrophotographic toner can be heated and melted to produce an electrophotographic toner having a spherical or substantially spherical agglomerated degree.

  Thus, according to the present invention, at least a colorant and a toner main resin are kneaded, the resulting mixture is pulverized, and the obtained pulverized product is melted in a superheated steam atmosphere to obtain a spherical or substantially spherical electrophotographic image. And a method for producing a toner for electrophotography.

  In addition, according to the present invention, the electrophotographic toner further includes a step of spraying the spherical or substantially spherical electrophotographic toner from a superheated steam atmosphere through a nozzle to a reduced pressure space, and drying and collecting the electrophotographic toner. A toner manufacturing method is provided.

  Furthermore, there is provided a method for producing an electrophotographic toner, further comprising a step of classifying the spherical or substantially spherical electrophotographic toner using an air current.

  According to the present invention, in the electrophotographic toner manufacturing method in which the pulverized electrophotographic toner is heated and melted in a high-temperature atmosphere to make the shape of the electrophotographic toner spherical, a steam generator is used as the heating and melting means. The superheated steam generated by heating the steam generated from the superheated steam generator to a higher temperature is used, and an electrophotographic toner having a large number of irregularities on the surface after pulverization is used in the atmosphere of the superheated steam. The electrophotographic toner that has been sprayed into the spheroidized body by heat melting has a reduced degree of aggregation of the electrophotographic toner and is pulverized compared to the conventional method of heat melting in high-temperature dry air. It is easy to make the later electrophotographic toner spherical or substantially spherical, and it provides a method for producing an electrophotographic toner having high production efficiency and excellent transferability.

  According to the present invention, there is provided a method for producing an electrophotographic toner, wherein the spherical or substantially spherical electrophotographic toner has an average circularity of 0.900 to 0.998.

  The term “substantially spherical” used in the present invention means a shape that is very close to a sphere. Specifically, when one particle of the electrophotographic toner is observed, the particle size in the horizontal direction, the particle size in the vertical direction, or the particle size in the arbitrary direction is compared, and the average value of these particles is compared with the average value. It means that each error in particle size falls within a range of at least ± 20%, preferably within a range of ± 15%, more preferably within a range of ± 10%.

  According to the invention, the kneading of the colorant and the toner main resin is kneading under heating and melting, and the resulting mixture is cooled, pulverized, and further classified. A method is provided.

  The main resin material of the electrophotographic toner that can be used in the electrophotographic toner production method according to the present invention is not particularly limited as long as it is generally used as an electrophotographic toner.

  Examples of the toner resin material for electrophotography include polyester-based, polyolefin-based, styrene-based, for example, styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and substituted homopolymers thereof, and styrene-p-chlorostyrene. Polymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid resin such as styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer And a styrene-butyl acrylate copolymer, a styrene-octyl acrylate copolymer, or a styrene-methacrylic acid resin such as a styrene-methyl methacrylate copolymer.

  Among these, when the toner main resin is a styrene-acrylic acid resin, a styrene-methacrylic acid resin, or a polyester resin, the performance as a toner is particularly excellent, which is preferable.

  Furthermore, in order to increase the mechanical strength and fixing strength of the toner, a polyester resin material containing a high molecular weight component is suitably used as the toner main resin material.

The colorant that can be used in the method for producing an electrophotographic toner according to the present invention may be either an organic pigment or an inorganic pigment, or may be a pigment made of a metal.
As the organic pigment, for example, a phthalocyanine pigment such as phthalocyanine blue, an insoluble azo pigment such as benzidine yellow, and the like can be used, but this is an example and not all.

  Examples of inorganic pigments include natural products such as mica and ocher, chromates such as yellow lead, zinc yellow and barium yellow, ferrocyanides such as bitumen, sulfates such as barium sulfate, lead sulfate and strontium sulfate. Zinc oxide, titanium white, benkara, iron black, oxides such as chromium oxide, hydroxides such as aluminum hydroxide, silicates such as calcium silicate, carbonates such as calcium carbonate and magnesium carbonate, carbon black, etc. Carbon fine powder, or metal powder such as aluminum powder.

In the method for producing an electrophotographic toner according to the present invention, in addition to the toner main resin and the colorant, a material containing a quaternary ammonium salt, a resin system, or a metal is dispersed in the toner main resin material as a charge control agent. It can also be used.
Examples of the charge control agent include a resin-based styrene-acrylic copolymer, a metal-containing tetraphenylborate, and a metal salt of a salicylic acid derivative. In particular, from the viewpoint of toner charge stability in an environment. To metal salts of salicylic acid derivatives.

  The addition amount of the metal salt of the salicylic acid derivative can be added in an amount of 0.1 to 10% by weight based on the total amount of the toner main resin and the colorant. Can be secured.

  The toner main resin, the colorant and the antistatic agent are kneaded by a method known to those skilled in the art. That is, for example, the above materials can be dispersed and mixed with a mixer, and then melt-kneaded using, for example, a biaxial open roller type superheated melt kneader to obtain a resin mixture.

  The resin mixture thus obtained is pulverized and classified by a method known to those skilled in the art. That is, for example, fine pulverization is performed using a ball mill or a jet airflow pulverizer, and classification is performed using, for example, a classification device.

  Next, the pulverized product obtained above is subjected to a step of melting in a superheated steam atmosphere to obtain a spherical or substantially spherical electrophotographic toner. In the present invention, any of the apparatuses shown in FIGS. 2 to 6 can be used for this step.

  Specifically, the pulverized material obtained as described above is discharged by the conveying air into the atmosphere of superheated steam in which superheated steam is jetted. The pulverized product released in the atmosphere of superheated steam is covered not only on its surface but also on the uneven surface of the pulverized product surface with superheated steam, and is heated instantaneously to the inside by the thermal energy obtained by condensation of the superheated steam. The The main resin component of the electrophotographic toner is melted by this thermal energy, and is molded into a spherical shape or a substantially spherical shape by the surface tension of the resin component itself in a solution state.

  The preferred temperature of the above-mentioned superheated steam was determined as follows by the apparatus used in the electrophotographic production method whose schematic diagram is shown in FIG.

  Specifically, in FIG. 5, the electrophotographic toner 100 that has undergone the pulverization / classification process is transported in the atmosphere of superheated steam 35 generated by the superheated steam generation process by the airflow of the transporting air 15. That is, a mixed airflow is formed downstream of the nozzle 10 that ejects the electrophotographic toner 100 and the nozzle 11 that ejects the superheated steam 35, and the electrophotographic toner 100 and the superheated steam 35 are mutually in the mixed airflow. By contacting, the heat energy of the superheated water vapor 35 is transmitted to the electrophotographic toner 100, and the electrophotographic toner 100 is heated and melted to be spheroidized.

  However, if the heat energy of the superheated steam 35 is too low in the above process, the resin material of the electrophotographic toner 100 is not melted by heating and cannot be made spherical.

  On the other hand, if the thermal energy of the superheated steam 35 is too high, the resin material of the electrophotographic toner 100 can of course be heated and melted. However, the resin material deteriorates and is uniformly dispersed in the resin material. As a result, the colorant particles that are present agglomerate, which adversely affects color development during image formation.

As described above, the superheating temperature of the superheated steam 35 has an appropriate temperature, and when the temperature is lower than the appropriate temperature, it does not spheroidize, and at a high temperature, the resin and the output image deteriorate.
In the present invention, the superheated steam temperature at which sufficient heat energy can be supplied to spheroidize the electrophotographic toner 100, and the resin material and the colorant particles forming the electrophotographic toner 100 are deteriorated. Therefore, it is necessary to heat and melt the electrophotographic toner at a superheated steam temperature that does not cause the heat generation.

Therefore, based on the above phenomenon, the present inventor determined a suitable temperature of superheated steam as follows.
FIG. 5 shows a schematic view of an apparatus used in an electrophotographic toner manufacturing method which is one embodiment of the present invention. The apparatus includes a superheated steam generation process including a steam generation apparatus 20 that generates steam and a superheated steam generation apparatus 30 that heats the steam to 100 ° C. or more, and an apparatus that is involved in the spheroidization process of the electrophotographic toner 100. For the purpose of controlling the superheated steam temperature, a temperature sensor 250 for measuring the ambient temperature in the mixed air stream in the apparatus part on the spheronization process side, and an apparatus part on the superheated steam generation process side, that is, superheat for heating the steam The steam generator 30 is characterized by having a superheated steam temperature control process comprising a heating temperature control device 260 for controlling the temperature of superheated steam based on temperature information from the temperature sensor 250.

  The present inventor set the set temperature of the superheat temperature control device 260 at intervals of 50 ° C. within the range of 100 ° C. to 400 ° C. using the above-described apparatus, and actually manufactured the toner for electrophotography. No change in the shape of the electrophotographic toner 100 could be confirmed with water vapor at 0 ° C.

  On the other hand, with the superheated steam 35 at 150 ° C. or higher, the electrophotographic toner 100 has a spherical shape.

  However, at 350 ° C. or higher, the electrophotographic toner 100 has a spherical shape. However, when the image is output, the color developability is poor and the fixing property to the recording paper is not good. Is too high, and it is considered that deterioration of the resin material, aggregation of the colorant, and the like occur.

  That is, the present inventor can make the shape of the electrophotographic toner 100 spherical by setting the temperature of the superheated steam 35 generated from the superheated steam generator 30 to a temperature range of 150 ° C. to 300 ° C. In addition, it has been found that a spheroidized electrophotographic toner 110 having good color developability even when an image is output can be obtained.

  More specifically, when the temperature of the superheated steam 35 generated from the superheated steam generator 30 is set to a temperature range of 150 ° C. to 300 ° C., the inventor causes the electrophotographic toner 100 to undergo resin degradation or the like. In addition, the inventors have found that a spherical or substantially spherical toner for electrophotography can be easily produced without causing colorant aggregation.

  That is, according to the present invention, there is provided an electrophotographic toner manufacturing method in which the temperature in the superheated steam atmosphere is in a temperature range of 150 ° C to 300 ° C.

  The present inventor has also examined the flow velocity of the conveying air for injecting the electrophotographic toner 100 that has undergone the pulverization and classification steps into a superheated steam atmosphere. As a result, it has been found that it is suitable for producing an electrophotographic toner that the electrophotographic toner is jetted with air for conveyance at a flow rate of 1 to 20 m / min, preferably 5 to 15 m / min.

  This is because the electrophotographic toner was not fluidized when the conveying air flow rate was 1 m / min or less, resulting in a decrease in conveying property. Conversely, when the conveying air has a flow velocity of 20 m / min or more, the toner is dispersed from the ejection port, and the electrophotographic toner adheres to the inner wall of the conveying tube.

  Furthermore, the present inventor also examined the flow rate of superheated steam injected from the superheated steam generator into the superheated steam atmosphere. As a result, it has been found that a flow velocity higher than that of toner conveying air is suitable for producing an electrophotographic toner.

  Therefore, according to the present invention, the pulverized product is transported into a superheated steam atmosphere by transporting air at a flow rate of 1 to 20 m / min, and the flow rate of the superheated steam is higher than that of the transporting air. A set electrophotographic toner manufacturing method is provided.

  Specifically, at a flow rate slower than that of the toner conveying air, when the toner conveying air and the superheated steam are merged in the container, the air flow of the superheated steam is bent toward the inner wall of the container, and the toner conveying The electrophotographic toner transported to the commercial air did not spheroidize without obtaining sufficient heat from the superheated steam.

  Therefore, according to the present invention, when the electrophotographic toner immediately after pulverization is spheroidized, the superheated steam has a higher flow rate than the air for toner conveyance, and the electrophotographic toner does not adhere to the container wall surface. A manufacturing method for spheroidizing an electrophotographic toner is provided.

  According to another aspect of the present invention, there is provided a method for producing an electrophotographic toner according to the present invention, wherein the electrophotographic toner having a spherical or substantially particle size is formed after the spheronization step of the electrophotographic toner in the superheated steam atmosphere. Can be collected in a decompression chamber 40 as shown in FIG.

  The greatest feature of collecting the spheroidized electrophotographic toner particles using the above-described decompression chamber is that the microparticles based on the superheated water vapor used in the spheronization process attached to the surface of the electrophotographic toner particles. Water droplets can be removed by evaporation under reduced pressure in the decompression chamber, and the photographic toner can be cooled in the process of evaporation of the water droplets.

  The decompression degree of the decompression chamber has an exhaust amount exceeding the sum of the conveying air and the superheated steam amount ejected from the toner ejection nozzle 10 and the superheated steam spray nozzle, for example, using an exhaust pump well known to those skilled in the art Is maintained.

  The exhaust amount of the exhaust pump is, for example, 10 to 45 L / min, preferably 20 to 45 L / min.

  Therefore, according to the present invention, there is provided an electrophotographic toner manufacturing method in which the decompression space is maintained at a reduced pressure by exhaust of 10 to 45 L / min.

EXAMPLES Hereinafter, although an Example, a comparative example, and with reference to drawings demonstrate this invention concretely, these Examples do not limit this invention at all.
Example 1
FIG. 1 shows a flowchart in an electrophotographic toner manufacturing method according to an embodiment of the present invention.

<< Step 1: Material mixing and hot melt kneading >>
In this embodiment, as a toner main resin material, a polyester resin material containing a high molecular weight (gelling) component (Haimar E-21: manufactured by Sanyo Chemical Industries, Ltd.) in order to satisfy mechanical strength and fixing strength. ) Is used. After weighing 91 parts by weight of the toner main resin material and 9 parts by weight of the colorant, the toner main resin for electrophotography and 5 kg of the colorant were dispersed and mixed using a Julia mixer (manufactured by Tokuju Kogakusho Co., Ltd.). Thereafter, melt kneading was performed using a biaxial open roller type heat melt kneader (Mitsui Mining Co., Ltd .: Kneedex MOS140-800). Specifically, a dispersion and mixture of the electrophotographic toner main resin and the colorant is accumulated in a supply hopper, and a resin melt kneading is performed while sequentially supplying a fixed amount to the open roller kneading apparatus. Yes. The open roller type kneader is provided with a separate supply feeder, and the supply feeder is set so that the metal complex salt of a salicylic acid derivative is 1% by weight based on the mixture of the toner main resin and the colorant as a charge control agent. And added.

<< Process 2: Crushing / Classification >>
After naturally cooling the resin kneaded product obtained in the above-mentioned step 1, it is finely pulverized with a jet airflow pulverizer (manufactured by Nippon Pneumatic Co., Ltd .: supersonic jet mill CPX-12), and a classifier (manufactured by Nippon Pneumatic Co., Ltd .: Using a classifier MP250), classification was carried out so that the number average particle diameter was 6.5 μm, and 4.5 kg of electrophotographic toner having no external additives attached to the particle surface was obtained.

<< Process 3: Spheroidization >>
In order to form the electrophotographic toner 100 obtained by the step 2 in a spherical shape or a substantially spherical shape with no external additive attached to the surface, in the present invention, the pulverized electrophotographic toner 100 is externally heated. It has a step of melting the resin itself in the gas phase heated by the apparatus. In this step, the melted electrophotographic toner resin is spheroidized by the surface tension. Accordingly, the shape of the toner resin obtained in this step is in a spherical or substantially spherical shape.

FIG. 2 is a schematic view of a production apparatus using the production method of the present invention for making the electrophotographic toner 100 spherical.
Specifically, the electrophotographic toner 100 obtained in the step 2 is put in a toner hopper 50. Although not shown here, the manufacturing apparatus is provided with a mechanism that allows the electrophotographic toner 100 to be supplied at a constant amount.

  The electrophotographic toner 100 is supplied from the charging port of the apparatus, and is conveyed to the ejection port of the toner ejection nozzle 10 by the conveyance air 15 at a flow rate of 5 to 15 m / min.

  In this apparatus, a superheated steam spray nozzle 11 is provided so as to surround the outer periphery of the toner spray nozzle 10. From the superheated steam injection nozzle 11, a steam generator 20 composed of a boiler that generates steam, and a superheated steam generator 30 that heats the steam obtained from the steam generator 20 to 100 ° C. or higher are 150 to 300 ° C. Of superheated steam 35 is injected at a flow rate of 5 to 15 m / min.

  The electrophotographic toner 100 ejected from the toner ejection nozzle 10 is discharged into the atmosphere of superheated steam 35 ejected from the superheated steam ejection nozzle 11. Then, it is heated instantaneously to the inside in a superheated steam atmosphere, the main resin component melts, and is formed into a spherical shape or a substantially spherical shape by the surface tension of the resin material. The spherical electrophotographic toner 110 reaches the cooling chamber 60 where the cooling air flows as a swirling flow, and is cooled and held in a spherical shape while being transported in the swirling flow, from the cooling chamber. The toner is collected to the toner collecting device 70.

<< Step 4: External processing >>
In order to secure further fluidity with respect to the spherical or substantially spherical electrophotographic toner obtained in the step 3, silica fine particles having an average particle diameter of 0.1 μm or less are about the total amount of the electrophotographic toner. An amount of about 1% by weight was externally added. The fine particles are only an example by the silica gel chromatography, and various inorganic fine particles and organic fine particles may be used as long as they improve the fluidity of the electrophotographic toner.

  For example, examples of the inorganic fine particles include the above-described hydrophobic silica fine particles, metal fine particles such as titanium oxide and alumina. The organic fine particles are not particularly limited, for example, fine particles such as silicon, melamine, and polystyrene can be used. However, in order to improve the transfer performance, for example, agglomerated silica fine particles may be used.

  In this embodiment, an external additive is bonded to the surface of the electrophotographic toner by mechanical energy.

Specifically, a surface modification device (Nara Machinery Co., Ltd .: Hybridization System NHS-0 type) mixes and disperses the toner for electrophotography as a base particle and silica fine particles as a child particle and puts it into a hybridizer. Then, the child particles were immobilized on the surface of the mother particles while being dispersed in the gas phase.
Measurement of shape of toner particles To confirm the shape of the electrophotographic toner obtained in steps 1 to 4 of this example, a flow type particle image analyzer (Sysmex Corporation: EPIA-1000) was used. Circularity was measured.

  That is, a water-soluble dispersion stabilizer is dissolved in pure water to prepare a solution, and the electrophotographic toner according to the present invention is dispersed in the solution. In order to uniformly disperse, the electrophotographic toner can be more uniformly dispersed by vibrating the dispersion solution. The sphericity of the electrophotographic toner was evaluated using the particle circularity measuring function of the flow type particle image analyzer. In addition, the circularity of the particles is obtained by the following equation (1).

Formula (1): Average circularity = circumferential length of a circle having an area equal to the particle area / peripheral length of the particle Although it depends on production conditions, the average circularity of the obtained electrophotographic toner is 0.92 to 0. The particle shape was spherical or nearly spherical.

  In this example, in a conventional electrophotographic toner manufacturing method using a kneading and pulverizing method, the electrophotographic toner has a heating means for heating and melting the downstream side of the kneading and pulverizing process, and the heating means is overheated. The electrophotographic toner manufacturing method is characterized in that water vapor is used, the electrophotographic toner is heated and melted, and the electrophotographic toner shape is spheroidized.

Example 2
FIG. 3 shows a schematic diagram of an electrophotographic toner manufacturing method which is one embodiment of the present invention.
In the spheroidization process of the electrophotographic toner particles using superheated steam, the superheated steam 35 at 150 to 300 ° C. generated in the superheated steam generation process comprising the steam generator 20 and the superheated steam generator 30 is a superheated steam jet nozzle. 11 is injected at a flow rate of 5 to 15 m / min. The electrophotographic toner 100 is dispersed in the conveying air 15 at a flow rate of 5 to 20 m / min and ejected from the toner ejection nozzle 10. The electrophotographic toner 100 ejected from the toner ejection nozzle 10 and the superheated steam spray nozzle 11 and the superheated steam 35 are mixed in a mixing chamber 45 in the gas phase. At this time, the electrophotographic toner 100 in the vapor phase comes into contact with the superheated water vapor 35, and the thermal energy of the superheated water vapor 35 is transmitted to the electrophotographic toner 100, so that the electrophotographic toner 100 is There is a spheronization step in which the resin component of the electrophotographic toner 100 is heated and melted, and is formed into a sphere by the surface tension of the resin material.

The superheated water vapor 35 in the spheronization step transfers heat energy to the electrophotographic toner 100 and then aggregates on the surface of the electrophotographic toner 100 to form minute water droplets.
In the present embodiment, the spherical toner injection nozzle 12 is provided on the downstream side of the spheronization step for forming the electrophotographic toner 100 into a sphere with the superheated steam 35, and the decompression chamber 40 is provided on the ejection side of the spherical toner injection nozzle 12. It is characterized in that it has a drying process for removing minute water droplets adhering to the surface of the toner 100 for electrophotography.

  Specifically, when the electrophotographic toner 110 spheroidized from the spherical toner ejection nozzle 12 is ejected to a decompression chamber exhausted by an exhaust pump of 10 to 45 L / min, the electrophotographic toner The minute water droplets on the surface of the toner 110 are atomized by a sudden pressure change and evaporated from the electrophotographic toner 110, and the electrophotographic toner 110 is cooled by the evaporation of the water droplets.

  Therefore, according to the present method, the electrophotographic toner 110 can be obtained as a spheroidized electrophotographic toner 110 without having water droplets on the surface thereof, and the electrophotographic toner is the next step. This is a method for producing an electrophotographic toner that can be directly transported to an external addition process for improving the fluidity of the toner 110 for use.

Example 3
FIG. 4 shows a schematic view of a method for producing an electrophotographic toner which is one embodiment of the present invention.
The electrophotographic toner 100 that has undergone the pulverization / classification process is conveyed in the atmosphere of the superheated steam 35 generated by the superheated steam generation process with the airflow of the transporting air 15. Specifically, a mixed air flow is formed downstream of the jet outlet of the toner jet nozzle 10 that jets the electrophotographic toner 100 and the superheated steam jet nozzle 11 that jets the superheated steam 35, and the electrophotographic toner 100 and the superheated When the water vapor 35 comes into contact with each other in the mixed air stream, the heat energy of the superheated water vapor 35 is transmitted to the electrophotographic toner 100, and the electrophotographic toner 100 is heated and melted. Turn into.

  The spherical electrophotographic toner 100 is cooled in a cooling chamber 60 that forms a spiral airflow. From the outlet of the cooling chamber 60, the spherical electrophotographic toner 110 is ejected. The electrophotographic toner 110 transported to the cyclone dust collector 200 by the transporting air is jetted into the cyclone dust collector 200 from a nozzle attached to the cyclone dust collector 200. Although not shown here, the cyclone dust collector 200 is separately provided with a spiral and dry airflow inside, and the electrophotographic toner ejected from the nozzle is the spiral and dry airflow. It is conveyed to. With the electrophotographic toner 110 dispersed in the spiral airflow, the electrophotographic toner 110 satisfying a desired particle size distribution can be obtained. Further, the large particle diameter side of the electrophotographic toner 110 that does not satisfy the desired particle size distribution is collected by a collecting mechanism separately provided in the cyclone dust collector 200, and is also minutely floating in a spiral airflow. The electrophotographic toner 110 is collected by the bag filter 210. The airflow after collecting the minute electrophotographic toner is finally released into the atmosphere.

  In this embodiment, the step of collecting the electrophotographic toner having a desired particle diameter efficiently by collecting the electrophotographic toner having a large particle diameter separately by the spiral airflow of the cyclone dust collector 200. The electrophotographic toner 110 collected in the above process has a sharp particle size distribution, and an electrophotographic toner having a very narrow particle size distribution can be easily and inexpensively. An electrophotographic toner manufacturing method characterized in that the toner can be manufactured easily.

Example 4
FIG. 5 shows a schematic view of the electrophotographic toner manufacturing method according to the embodiment of the present invention.
The electrophotographic toner 100 that has undergone the pulverization / classification step is superheated water vapor at a flow rate of 5 to 10 m / min at 150 to 300 ° C. generated by the superheated steam generation step with a flow of air 12 for conveyance at a flow rate of 5 to 15 m / min. It is conveyed in 35 atmospheres. Specifically, a mixed airflow is formed on the downstream side of the nozzle 10 for ejecting the electrophotographic toner 100 and the nozzle 11 for ejecting the superheated steam 35, and the electrophotographic toner 100 and the superheated steam 35 are mixed. The heat energy of the superheated water vapor 35 is transmitted to the electrophotographic toner 100 by being brought into contact with each other, and the electrophotographic toner 100 is heated and melted into a sphere.

  Therefore, in this embodiment, by determining the superheated steam temperature to be 150 ° C. to 300 ° C., the electrophotographic toner 100 can be easily manufactured without causing resin spheroidization or the like. This is a toner manufacturing method.

Comparative Example A spherical toner obtained by dispersing the electrophotographic toner obtained by the pulverization method in a conventional high-temperature dry gas phase and making the shape spherical, and obtaining the spherical shape obtained in the present invention Comparison with toner (FIG. 6).

  Specifically, in FIG. 2 showing a schematic diagram of the apparatus used in Example 1, instead of a boiler that generates superheated steam, a boiler that only heats dry air is provided, and dry air heated to a high temperature is implemented. The toner is introduced into the apparatus of Example 1 and ejected from the outer periphery of the toner ejection nozzle 10 under the same conditions as in Example 1. In addition, the electrophotographic toner 100 having irregularities on the surface after pulverization is discharged from the ejection port of the toner ejection nozzle 10 into high-temperature dry air under the same conditions as in the first embodiment.

  The electrophotographic toner released into the high-temperature dry air is heated from the resin surface by the thermal energy of the high-temperature dry air, the resin surface of the electrophotographic toner is heated and melted, and the shape is spherical due to the surface tension of the resin material. Then, the temperature of the electrophotographic toner is lowered by cooling air and then taken out to the outside.

  Regarding the electrophotographic toner obtained in this comparative example (hereinafter referred to as comparative example toner) and the electrophotographic toner produced in Example 1 of the present invention (hereinafter referred to as toner of the present invention), (a) specific charge amount, (b A comparative study was made on the degree of circularity, (c) average particle diameter, and (d) transferability.

(a) Specific charge amount The toner of the present invention and the comparative example toner were each converted into a developer using the carrier of our digital full color multi-function printer “MX-2700FG”, and then both developers were respectively mixed on a roll mill for 10 minutes. After stirring and mixing, measurement was performed using a suction type small charge amount measuring device (manufactured by Trek Japan Co., Ltd .: Model 210HS-2A).

(b) Circularity In order to determine the sphericity of the toner of the present invention and the comparative toner, the circularity was measured using a flow type particle image analyzer (Sysmec Corporation: EPIA-1000).

(c) an average particle diameter of the present invention the toner of each of Comparative Toner, to prepare a solution of a surfactant in pure water, a dispersion prepared by dispersing the main invention toner in the solution, the After preparing each dispersion solution in which the toner of the comparative example was dispersed in the solution, measurement was performed using a particle size distribution measuring apparatus (Beckman Coulter, Inc .: Multisizer II).

(d) Transferability The developer prepared with the above (a) specific charge amount is placed in the development unit of our digital full-color MFP “MX-2700FG”. After printing the prescribed test sample, as shown in FIG. 7, a part of the character portion was enlarged with a stereomicroscope to confirm the image quality on the paper.

The measurement / evaluation results of the above items are summarized in Table 1.
In the column of “Transferability” in the above table, “◯” means that there is no gap inside the character, and “X” means that there is a gap inside the character.
From the above evaluation results, the toner of the present invention was closer to a sphere than the comparative toner, and the average particle size was 6.5 μm before the spheroidizing treatment. The average particle size of the toner of the present invention after the spheronization treatment was 7.2 μm, and the average particle size of the comparative toner was 8.6 μm. Therefore, the toner of the present invention is generated during the spheronization processing. It can be seen that the presence of toner aggregates is small.

  Further, from the enlarged photograph after the test sample printing shown in FIG. 7, the toner of the present invention causes a phenomenon that the printing part is lost (the developer is not attached to a part of the printing part) as compared with the comparative toner. It was found that good image quality can be obtained.

  As described above, according to the present invention, in the method for producing an electrophotographic toner, the electrophotographic toner after pulverization is heated and melted in a high-temperature atmosphere so that the shape of the electrophotographic toner is spheroidized. There is provided an electrophotographic toner manufacturing method characterized by using, as means for heating and melting photographic toner, a steam generator and superheated steam generated from a superheated steam generator that heats the steam generated from the apparatus to a higher temperature. Provided. By using the electrophotographic toner manufacturing method of the present invention, a spheroidized electron obtained by injecting an electrophotographic toner having a large number of irregularities on the surface after pulverization into the superheated steam atmosphere and heating and melting it is obtained. The photographic toner can reduce the degree of aggregation of the electrophotographic toner as compared with the toner particles obtained by the conventional heat melting method in high-temperature dry air. In addition, it is possible to provide a method for producing an electrophotographic toner having excellent transferability.

3 is a flowchart for manufacturing an electrophotographic toner according to the first exemplary embodiment. 1 is a schematic view of an electrophotographic toner manufacturing apparatus of Example 1. FIG. FIG. 4 is a schematic view of an electrophotographic toner production apparatus of Example 2. FIG. 6 is a schematic view of an electrophotographic toner production apparatus of Example 3. FIG. 6 is a schematic view of an electrophotographic toner production apparatus of Example 4. FIG. 3 is a schematic view of an electrophotographic toner manufacturing apparatus of a comparative example. It is a printing result of the toner for electrophotography of a present Example and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Toner injection nozzle 11 ... Superheated steam injection nozzle 12 ... Spherical toner injection nozzle 15 ... Conveying air 20 ... Steam generation device 30 ... ... Superheated steam generator 35 ... Superheated steam 40 ... Decompression chamber 45 ... Mixing chamber

50 ... Electrophotographic toner hopper 60 ... Cooling chamber 70 ... Electrophotographic toner collector 100 ... Electrophotographic toner 110 ... Sphericalized Toner for electrophotography 200 ... Cyclone dust collector 210 ... Bag filter 250 ... Temperature sensor 260 ... Superheated steam temperature control device 300 ... High temperature dry air jet nozzle 310 ... Heating boiler 320 ... High temperature dry air

Claims (10)

  A step of kneading at least a colorant and a toner main resin and pulverizing the resulting mixture; and a step of melting the obtained pulverized product in a superheated steam atmosphere to obtain a spherical or substantially spherical electrophotographic toner. A method for producing toner for electrophotography. The method for producing an electrophotographic toner further includes a step of spraying the spherical or substantially spherical electrophotographic toner from a superheated steam atmosphere through a nozzle to a reduced pressure space, and drying and collecting the electrophotographic toner. Item 2. The method for producing an electrophotographic toner according to Item 1. The electrophotographic toner manufacturing method according to claim 1, wherein the electrophotographic toner manufacturing method further includes a step of classifying the spherical or substantially spherical electrophotographic toner using an air flow. The superheated steam atmosphere is obtained by injecting the pulverized product with transport air for transporting the pulverized product into superheated steam obtained by further heating the steam generated by the steam generator with the superheated steam generator. The method for producing an electrophotographic toner according to any one of claims 1 to 3 . The method for producing an electrophotographic toner according to any one of claims 1 to 4 , wherein the superheated steam atmosphere is in a temperature range of 150C to 300C. Before Symbol electronic photographic toner, electrophotographic toner production method according to any one of claims 1 to 5 that have a mean circularity of from 0.900 to 0.998. Before Symbol mixed kneaded is carried out under heating and melting of the coloring agent and the toner main resin, the resulting mixture, after being cooled, crushed, further classified to claim 1-6 The method for producing an electrophotographic toner according to claim. The pulverized material, the conveying air flow rate 1-20 m / min, overheating is transported in a water vapor atmosphere, further, the superheated water vapor is claim is set to be higher flow rates than the transporting air 1 The method for producing a toner for electrophotography according to any one of 7 to 7 . The method for producing an electrophotographic toner according to any one of claims 1 to 8 , wherein the toner main resin is a styrene-acrylic acid copolymer, a styrene-methacrylic acid copolymer, or a polyester resin.   The method for producing an electrophotographic toner according to claim 2, wherein the decompression space is maintained at a reduced pressure by exhausting 10 to 45 L / min.