JP2000081725A - Production of toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a toner excellent in characteristics by uniformly and efficiently drying wet toner particles obtd. by direct polymn. while removing an unreacted polymerizable monomer. SOLUTION: A polymerizable monomer compsn. contg. at least a polymerizable monomer and a colorant is polymerized in an aq. medium to form colored polymer particles and these particles are washed and dehydrated. The resultant wet colored polymer particles are dried with hot air to 0.1 to <1.0% water content, an additive is added to the colored polymer particles and vacuum drying is further carried out under stirring until the amt. of the unreacted polymerizable monomer remaining in the colored polymer particles is reduced to <=200 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner for developing an electrostatic image or a toner for forming a toner-fixed image in a toner jet image forming method in an image forming method such as electronic printing. More particularly, the present invention relates to a method for producing a toner to be used in a fixing method in which a toner image is heated and pressed and fixed on a print sheet such as a transfer material.

[0002]

2. Description of the Related Art Electrophotography is disclosed in U.S. Pat.
Although a number of methods are known as described in, for example, US Pat. No. 691 and the like, in general, an electric latent image is formed on a photoreceptor by various means using a photoconductive substance, The latent image is developed using fine particles of a colored resin composition called a toner, and, if necessary, the toner image is transferred from a photoreceptor to a transfer material such as paper, and then heated, pressured, or vaporized. For example, a copy or print is obtained by fixing the image on a transfer material. Also, in the above method, various methods have been conventionally proposed as a method of developing a latent image using toner or a method of fixing a toner image on a transfer material, and are suitable for each image forming process. The method has been adopted.

[0003] Further, conventionally, a toner used for developing an electric latent image is generally contained in a thermoplastic resin.
A colorant such as a dye or a pigment is melt-mixed, and after uniformly dispersing these materials, a finely pulverized product is obtained by a finely pulverizing device. Thereafter, the finely pulverized product is classified using a classifier, and a desired particle size is obtained. (A resin colorant dispersion) is obtained by a so-called pulverization method. According to the above-described method for producing a toner by a pulverization method, a toner having considerably excellent characteristics can be produced, but there is a certain limitation, that is, a range of selection of a toner material is limited. For example, the resin colorant dispersion before milling must be sufficiently brittle to be millable in an economically feasible manufacturing equipment. However, if the resin colorant dispersion is made brittle to satisfy these requirements, the particle size range of the particles tends to be widened when actually pulverized at a high speed, and particularly a relatively large proportion of the fine particles are contained in the toner. The problem of inclusion occurs. Further, such a highly brittle material is susceptible to further pulverization or pulverization when used for development in a copying machine or the like. Further, in this method, it is difficult to completely and evenly disperse solid fine particles such as a colorant in a resin, and depending on the degree of the dispersion, when used for image formation, an increase in fog and an increase in image density are caused. Care must be taken in dispersing as this may cause deterioration, poor color mixing and transparency. Also, by exposing the colorant to the fracture surface,
In some cases, the development characteristics may fluctuate.

On the other hand, in order to overcome these problems with the toner formed by the pulverization method, Japanese Patent Publication No.
JP-A-10231, JP-B-43-10799 and JP-B-51-14895 have proposed various polymerization toners, including suspension polymerization toners, and methods for producing the same. For example, in the suspension polymerization method, a polymerizable monomer, a colorant and a polymerization initiator, and if necessary, a crosslinking agent, a charge control agent, and other additives are uniformly dissolved or dispersed to form a polymerizable monomer. After preparing the monomer composition, the monomer composition is dispersed in a continuous phase containing a dispersion stabilizer, for example, an aqueous phase using an appropriate stirrer, granulated, and simultaneously subjected to a polymerization reaction. Thus, toner particles having a desired particle size are obtained.

[0005] In the method for producing a toner utilizing such a polymerization method, no pulverizing step is included, so that the material for forming the toner is not required to be brittle as in the case of producing by the pulverizing method. , Soft materials can be used. In addition, since the classification step can be omitted, the cost can be greatly reduced by saving energy, shortening the manufacturing time and improving the process yield. In recent years, there have been various demands for high image quality, full color, energy saving, and the like in copiers and printers, and multifunctionality is also required for toner itself. For example, as the image quality increases, it is required to reduce the particle size of the toner particles corresponding to the high resolution and digital system, and the transparency of the OHP image, which is required with full color, and the low-temperature fixing with the energy saving, are required. Therefore, it is required that the toner contain a low softening point substance in the toner, and that the toner particles have a spherical shape, which is effective for improving the transfer efficiency to the transfer material. As a means for obtaining a toner that satisfies these requirements, the above-described method for producing a toner by the polymerization method is mentioned.

However, in the suspension polymerization method, including the case of the suspension polymerization method toner, in the reaction form, the viscosity of the polymerization reaction system increases as the polymerization proceeds, and the transfer of radicals and polymerizable monomers becomes difficult. Therefore, there is a problem that a large amount of the polymerizable monomer component tends to remain in the polymer. In particular, in the case of a suspension polymerization method toner, a polymerization reaction is suppressed by a dye or pigment (particularly, carbon black) as a colorant, a charge control agent or a magnetic substance added as needed, and the like in the polymerization system. Since there is a large amount of a component that may be present in the polymerizable monomer composition, particularly, unreacted polymerizable monomer tends to remain.

Further, if a large amount of a component that functions as a solvent for the binder resin is contained in these polymerized toner particles, not only the polymerizable monomer, but the fluidity of the toner is reduced, and the image quality is deteriorated. In addition, the blocking resistance is lowered. In addition to the performance directly related to the toner as described above, especially when an organic semiconductor is used as the photoconductor, the phenomenon of fusion of the toner to the photoconductor drum, memory ghost and image In some cases, a problem associated with the deterioration phenomenon of the photoconductor such as blurring may occur. Further, in addition to matters relating to the performance of such products, there is also a problem that the polymerizable monomer component volatilizes at the time of fixing and emits an offensive odor.

[0008] In order to improve the above enumeration, as described in JP-A-7-92736, the residual amount of the polymerizable monomer present in the toner particles is reduced by 5%.
It has been proposed that the image quality be further reduced by reducing the amount to 00 ppm or less. Furthermore, as the miniaturization and personalization of copiers, printers, and the like have increased, the restrictions on the apparatus have increased, and the load on the toner for the above-mentioned problems has further increased.In recent years, environmental concerns have also increased. It is preferable to reduce the residual amount of the polymerizable monomer remaining in the particles to 200 ppm or less, and more preferably to 100 ppm or less.

The residual amount of the polymerizable monomer in the toner is 200
As a method for reducing the content to ppm or less, a known polymerizable monomer consumption promoting means used when a binder resin is produced by a suspension polymerization method can be used. For example, as a method for removing the unreacted polymerizable monomer, a binder resin constituting the toner does not dissolve, but a polymerizable monomer and / or an organic solvent component dissolves. A method of washing the toner with a solvent; a method of washing the toner with an acid or an alkali; a solvent component that does not dissolve the foaming agent or the polymer (resin component) is put into a polymer system, and the resulting toner particles are made porous. A method of increasing the volatilization area of a polymerizable monomer and / or an organic solvent component in a toner and promoting the volatilization thereof; and a method of volatilizing a main synthetic monomer and / or an organic solvent component under dry conditions. Is mentioned. However, depending on the method, there is a problem that the toner constituent components are eluted due to the deterioration of the toner encapsulation property, and it is necessary to consider the residual property of the solvent used, and it is difficult to select a solvent. Therefore, among the above, the method of volatilizing the polymerizable monomer and / or the organic solvent component under dry conditions is most preferable.

Conventionally, various improvements have been made to a method for drying wet toner particles after solid-liquid separation of a suspension after the polymerization reaction. For example, Japanese Patent Application Laid-Open No. Sho 63-124055 proposes a method in which toner particles are suspended and suspended in a gas and dried while forming a fluidized bed. Further, Japanese Patent Application Laid-Open Nos. 4-31966 and 8-179562 propose a method of drying toner particles in a wet state using a fluidized-bed dryer. If the drying method is used, the toner can be efficiently dried.

However, since the above-mentioned unreacted polymerizable monomer generally has a boiling point higher than that of water, it cannot be effectively removed until almost all of the water has been completely removed. After the drying period, it cannot be effectively removed unless the reduced-rate drying is performed sufficiently. However, if moisture is removed, fine particles having good chargeability, such as toner particles,
Electrostatic adhesion is likely to occur on the wall surface of the flow chamber, and further, particles adhering to the wall surface of the flow chamber may be separated in a lump state. For this reason, there are problems that the removal of the unreacted polymerizable monomer becomes non-uniform as a whole and that the entire amount cannot be recovered after the treatment.

[0012] Japanese Patent Application Laid-Open No. Hei 6-324517 discloses that a wet toner particle or suspension obtained by solid-liquid separation of a suspension after polymerization reaction is directly dispersed in a hot air stream in the form of powder. Co-current with hot air flow (meaning flowing in the same direction)
A method of instantaneously drying while sending the paper to the factory has been proposed. In this method of drying toner particles by a hot air stream, water can be efficiently and continuously removed. However, as described above, the unreacted polymerizable monomer can hardly be removed by instantaneous drying.

Further, Japanese Patent Application Laid-Open No. 8-160662 proposes a method of drying wet toner with a vacuum dryer. However, in this drying method, after removing water by evaporation, further removal of unreacted polymerizable monomers not only requires an extremely long drying time, but also causes drying in a vacuum state. The following problem occurs. That is, first, at the stage of removing moisture, the toner is tightened and agglomerated due to the vacuum state in the apparatus, and a compacted state is formed. The formation of this compacted state becomes remarkable when the water content becomes 5% or less, the powder temperature rises, and the cohesive force between the powders starts to rise sharply. Further, when this compacted state is formed, toner adheres or fuses to the wall surface of the vacuum drying device or the stirring blade in the device, and the like.
The stable operation of the dryer is hindered. Further, lumps also occur due to aggregation of toners.

In the toner for developing an electrostatic image, various chemical substances are added in order to improve the image quality and attain the characteristics required for others. In order to improve various properties such as image quality and fogging, it is widely used to externally add various fine powders in order to improve fluidity and chargeability of toner. However, when lumps occur due to aggregation of toners,
When externally added to the toner in a later step, the external additive does not uniformly adhere to the toner surface, so that a problem easily occurs in the performance as a developer.

[0015]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a toner which has solved the above-mentioned problems. That is, an object of the present invention is to uniformly dry the toner particles in a wet state obtained by the direct polymerization method, and remove the unreacted polymerizable monomer, and efficiently dry the toner particles. An object of the present invention is to provide a method for producing a toner which can be easily obtained. Another object of the present invention is to provide a method for producing a toner capable of producing a toner capable of forming a high-quality image without causing image defects due to unreacted polymerizable monomers remaining in the toner. Is to do.

[0016]

The above objects are achieved by the present invention described below. That is, the present invention is obtained by polymerizing a polymerizable monomer composition containing at least a polymerizable monomer and a colorant in an aqueous medium to produce colored polymer particles, followed by washing and dehydration. The colored polymer particles in a wet state are dried using hot air to obtain a water content of 0.1.
After adding 1% or more to less than 1.0% of colored polymer particles, an external additive is added to the colored polymer particles, and the unreacted polymer remaining in the colored polymer particles is stirred while stirring. A toner under reduced pressure drying until the residual amount of the reactive monomer becomes 200 ppm or less. In particular, the present invention has an average particle size of 0.002 to 0.5.
A toner having an external additive of 2 μm, a material having a low softening point as a material for forming the toner, and a material having 1 carbon atom as a material having a low softening point
This is a method for producing a toner suitable for a toner containing an ester wax having one or more long-chain ester moieties of 0 or more.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to preferred embodiments of a method for producing a toner of the present invention. The present inventors have conducted intensive studies in order to solve the above-mentioned problems of the prior art, and as a result, polymerized a polymerizable monomer composition containing at least a polymerizable monomer and a colorant in an aqueous dispersion medium. After the colored polymer particles are formed, the polymer is washed and dehydrated, and the obtained wet colored polymer particles are dried using hot air to have a water content of 0.1% or more and 1.0% or more.
% After substantially removing the aqueous dispersion medium so as to have a concentration of less than 10% by weight, and then adding an external additive to the colored polymer particles and performing drying under reduced pressure while stirring them, the stable operation of the dryer is hindered. Therefore, generation of lumps due to aggregation of toners is suppressed, and the external additive can be uniformly attached.
In the drying step of the wet toner, the performance as a developer is not impaired, and the unreacted polymerizable monomer remaining in the toner particles is easily removed, and the remaining amount is 200.
The inventors have found that a toner having excellent characteristics of not more than ppm can be efficiently obtained, and have reached the present invention.

That is, an unreacted polymerizable monomer is removed by a fluidized bed dryer for drying a wet toner which has been conventionally used in a method for producing a polymerized toner, and the toner is used in a toner product. In order to reduce the residual amount of the unreacted polymerizable monomer to 200 ppm or less, it is necessary to continue drying even after the water content is removed to 0.1% or less (in terms of water content). However, there is a problem that a toner having excellent characteristics cannot be obtained efficiently. However, in the method for producing a toner of the present invention, these methods are improved by improving a drying means for polymerized toner particles in a wet state. Solve the problem at once. As described above, when the water content is reduced due to the removal of water, toner particles with chargeability adhere to the wall of the flow chamber of the dryer, and further,
Particles adhering to the wall of the fluidized chamber are peeled off in a lump state, and as a result, the removal of unreacted polymerizable monomers becomes uneven, resulting in a decrease in performance as a developer and a decrease in workability. Had a problem. In addition, when the drying is performed by using the (vacuum) decompression type drying method from the beginning, a very long drying time is required, and not only the workability is poor, but also when the water is removed, the toners are not separated from each other. In some cases, lumps due to aggregation were generated. When lumps occur, when an external additive is externally added to the toner for the purpose of imparting various properties to the toner after toner particles are formed, the external additive is not uniformly attached to the toner surface. In some cases, problems occurred. Further, it is difficult to remove the unreacted polymerizable monomer remaining in the particles from the inside of the aggregated lumps, and even if it is removed, it is likely to be non-uniform, which causes the same problem as described above. .

Hereinafter, the method for producing the toner of the present invention will be described in more detail. First, the drying step of the colored polymer particles (toner particles) obtained in a wet state by the polymerization method, which is performed in the method for producing a toner of the present invention, will be described. In the wet particle drying step performed in the present invention, first, the colored polymer particles in a wet state are heated with hot air to a water content of 0.1%.
The primary polymer is dried until it becomes less than 1.0%, and an external additive is added to the colored polymer particles after the primary drying, and then dried under reduced pressure while stirring them to obtain a final toner product. The residual amount of unreacted polymerizable monomer in
pm or less.

The object of the primary drying (drying) using the hot air to be performed first is performed by granulating and polymerizing a polymerizable monomer composition composed of a toner forming material to form colored polymer particles. After being produced, it is washed, the slurry containing the colored polymer particles is dehydrated, and the wet colored polymer particles obtained after the dehydration are obtained. In the present invention, in this case, the water content of the object to be dried composed of the colored polymer particles in a wet state to be subjected to drying, the fluidity of the powder is secured, and the drying efficiency is improved. It is preferable to adjust it to 40% or less. Furthermore, it is more preferable to provide the water whose moisture content has been adjusted to 30% or less for drying. The water content in the present invention refers to the moisture content based on the moisture content, that is, the ratio of the weight of water to the total weight (the sum of the weight of dry toner and the weight of water). The obtained value was used. The wet toner particles having such a water content can be easily obtained from the polymerization system by ordinary solid-liquid separation means (for example, filtration). However, preliminary drying is performed to obtain an optimum water content. Is also good.

In the method for producing a toner according to the present invention, first, the above-mentioned object to be dried is first dried using hot air until the water content becomes 0.1% or more and less than 1.0%. As a drying method using hot air that can be used in the present invention, for example, a material to be dried is dried (wet colored polymer particles).
Are preferably dispersed in a hot air stream in the form of powder and granules, and the drying is carried out while being sent in parallel with the hot air stream, or the drying method is carried out by suspending and suspending the material to be dried to form a fluidized bed.

As an apparatus for instantaneously drying an object to be dried in a hot air flow while dispersing it in a powdery and granular form and sending it in parallel with a high-speed hot air flow, for example, a loop-type drying apparatus as shown in FIG. A flash dryer having a tube 2 can be used. However, the present invention is not particularly limited to this.
In the hot-air dryer shown in FIG. 1, compressed air heated to a predetermined temperature in the hot-air generator 1 is discharged at a supersonic speed in the air-flow dispersing unit 3, and the dried material supplied from the slurry or wet particle supply device 6 is supplied. Are dispersed and dried instantaneously (0.5 to 10 seconds) in the loop-type flash drying tube 2. In this apparatus, the dried product and the undried product are classified by the Coanda effect by arranging the air flow outlet 4 inside the loop-shaped air drying tube, and only the dried product is separated from the air flow by the cyclone 5 and taken out. It is configured to go out of the system through the mouth 7. Further, the coarse particles in the particles coming out of the drying tube 2 are classified by a classifier separately and returned to the drying object supply device 6 so that only the particles in a certain particle size range are supplied to the cyclone 5. If desired, desired toner particles can be obtained, and classification and drying can be performed continuously. As the type of drying tube of the flash dryer, in addition to the above-mentioned loop type, straight tube type,
Various types of drying tubes can be used, such as an enlarged middle body for increasing the residence time, and a type in which swirling motion is applied to particles to prevent the particles from accumulating at the bottom of the horizontal tube. In the present invention, it is most preferable to use a flash dryer having a loop-type drying tube as shown in FIG.

In the method for producing a toner according to the present invention, the drying with hot air using the above-described apparatus is carried out in a range of 40 to 40.
It is preferable to use a hot air flow generated by compressed air heated to 150 ° C, preferably 60 to 120 ° C. That is, when the heating temperature is lower than 40 ° C., the drying efficiency is reduced, and when the heating temperature is higher than 150 ° C., the toner is undesirably fused during the drying process. As a dryer for drying with hot air, which is preferably used in the method for producing a toner of the present invention, the above-mentioned material to be dried (wet particles) is dispersed in a high-speed hot air stream in the form of powder, and is co-current with the hot air stream. Specific examples of the apparatus for instantaneously drying while feeding are, for example, a flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.) and a flash dryer (manufactured by Hosokawa Micron Corporation). Specific examples of a system for suspending and suspending an object to be dried (wet particles) to form a fluidized bed and drying the fluidized bed include, for example, a fluidized bed dryer (manufactured by Okawara Seisakusho) and a vibrating fluidized bed dryer. (Manufactured by Chuo Kakoki). Any of these apparatuses can be suitably used in the method for producing the toner of the present invention, and granulation and polymerization are performed in an aqueous dispersion medium, and the colored polymer particles obtained in a wet state are dried with hot air using these apparatuses. By doing so, the aqueous dispersion medium can be efficiently removed, so that colored polymer particles having a water content of 0.1% or more and less than 1.0% can be easily obtained. In this case, the moisture content was measured by the heating loss method at 105 ° C. as described above.

In the method for producing the toner of the present invention, the colored polymer particles are dried by using hot air as described above, so that the water content of the colored polymer particles is in the range of 0.1% or more and less than 1.0%. After that, an external additive is added to the colored polymer particles that have been subjected to the primary drying, and then dried under reduced pressure while stirring them until the residual amount of the unreacted polymerizable monomer becomes 200 ppm or less. As the external additive used in the present invention, in particular, an external additive which is added to obtain the final toner performance, for example, is effective for imparting fluidity or suppressing aggregation. After adding such an external additive to the colored polymer particles, they are dried under reduced pressure while stirring them,
In the depressurized dryer, the colored polymer particles circulate without causing adhesion and agglomeration of the particles, and furthermore, the adhesion between the particles and the device, and further, receive heat uniformly and efficiently from the outer wall of the dryer. Therefore, the unreacted polymerizable monomer remaining in the toner particles can be removed in a short time. As a result, the residual amount of the unreacted polymerizable monomer can be efficiently reduced to 200 ppm or less. Furthermore, when the colored polymer particles are taken out of the reduced-pressure dryer after the drying is completed, the polymer particles have good fluidity, so that they can be taken out without adhesion to the apparatus.

An external additive is added to the colored polymer particles from which the aqueous dispersion medium has been substantially removed, which is used in the method of producing the toner of the present invention, and a stirring mechanism is used for drying in this state. Vacuum dryer (vacuum)
Any device can be used without particular limitation as long as it can dry the colored polymer particles in a dry state. In the present invention, for example, a stirring and depressurizing drier having an aspect as shown in the schematic sectional views shown in FIGS. 2 and 3 is preferably used.
These will be described below.

In the drier shown in FIG. 2, the particles to be dried are supplied and dried in an inverted conical drying container 32. In the drying container 32, a driving device disposed above the container 32 is provided. A screw-type stirring member 35 connected to the device 33 via a drive arm 34 is provided.
Is configured to rotate along the inner peripheral surface of the container 32 while rotating. For this reason, in the dryer illustrated in FIG. 2, since the particles to be dried in the container 32 are repeatedly stirred and dispersed while being lifted from below, the particles to be dried are efficiently stirred and mixed throughout the entire container 32. You.

As shown in FIG. 2, a material supply port 36 for supplying particles to be dried is provided at an upper portion of the container 32.
An exhaust port 37 is provided for exhausting the gas in the container 32 when depressurizing the inside of the container and drying under reduced pressure while supplying gas. The airtight lid 16 is attached to the raw material supply port 36, and the bag filter 10 is connected to the exhaust port 37. Further, below the dryer, an outlet 38 for removing the dried product is provided.
The take-out valve 39 is connected and provided. Container 3
When the pressure in the container 2 is reduced, the gas in the container 2 is exhausted from the exhaust port 37 by the vacuum pump 28 through the bag filter 10 and the cold trap 20.

Further, as shown in FIG. 2, a jacket 11 is provided around the drying container 32 for appropriately controlling the temperature in the drying container 32 and enabling drying at a desired temperature. Is attached. Therefore, the drying container 3
A gap is formed between the outer wall 2 and the inner wall of the jacket 11, and the jacket 11 has a steam supply port 12, so that heating steam or cooling water can pass through the gap.
A cooling water supply port 13 and a steam or cooling water discharge port 14 are provided. The steam supply port 12 is connected to a steam generator boiler (not shown), and the cooling water supply port 13 is connected to a cooling water pump 16. Further, the drying container 32 is provided with steam inlets 17 at two positions above and below the container 32, and the steam inlet 17 on the lower side is provided.
By increasing the supply amount of steam from the steam, the effect of stirring the raw material at the time of steam injection is obtained.
Each of these steam inlets 17 is provided with an accumulator 1
8 is connected to a steam generating boiler 19. The accumulator 18 is for quickly feeding saturated or superheated steam into the container 32, and is indispensable for ending the heating of the raw material in the container 32 in a short time and setting the raw material to an optimal drying temperature. It is.

As described above, the pressure in the container 2 is reduced by the vacuum pump 28 from the exhaust port 7 to the bag filter 10.
This is performed by evacuating the gas in the container 2 through the cold trap 20. As shown in FIG. 2, the inside of the bag filter 10 is divided into two upper and lower chambers by a partition plate 21. A tubular filter cloth 22 is suspended below the partition plate 21, and an exhaust port 23 connected to the cold trap 20 is provided above the partition plate 21, and a position above the center of the filter cloth 22. Is provided with a cleaning nozzle 24. The washing nozzle 24 is for intermittently jetting high-pressure air from the compressor 25 to wash the filter cloth 22 under the reverse pressure. Further, the filter 26 and the washing nozzle 24
An accumulator 27 is provided between the two. The accumulator 27 compensates for a shortage of the supply of high-pressure air on the compressor 25 side, sends a constant amount of high-pressure air to the cleaning nozzle 24 in a stable state with little pressure fluctuation, and adjusts the flow rate of air passing through the filter 26 and It is provided to keep the passage speed substantially constant and to stabilize the filtering effect by the filter 26.

The supply of gas into the container 32 in the case of drying under reduced pressure while supplying gas is performed from a gas inlet 30 provided at the lower part of the apparatus. By drying under reduced pressure while supplying a gas in this manner, blocking of the toner, which is likely to occur at the lower portion in the apparatus, is suppressed, and evaporation of attached moisture or residual polymerizable monomer from the surface of the raw material particles is efficiently performed. Work as a carrier gas for
Therefore, it is preferable to supply gas from the viewpoint of improving efficiency. The gas supplied into the drying container 32 becomes a humidified gas containing water from the raw material particles, residual polymerizable monomer, and the like, and is exhausted from the bag filter 10 through the exhaust port 23. Then, the exhausted humidified gas is sent to the cold trap 20, and a liquid such as condensed moisture is discharged as a drain from the cold trap 20, while a gas component is removed from the vacuum connected to the cold trap 20. The gas is exhausted to the outside by the pump 28. still,
A pump 29 for feeding cooling water is connected to the cold trap 20 so that the humidified gas can be cooled and gas-liquid separation can be performed efficiently.

Next, another example of a dryer that can be suitably used in the method for producing a polymer of the present invention will be described with reference to FIG. The drier shown in FIG. 3 includes a driving device 33 disposed above a drying container 32 having an inverted conical shape,
The ribbon wing 40 having a double spiral structure is configured to rotate. With such a configuration,
Since the agitation and dispersion can be repeatedly applied while the material to be dried supplied into the container 32 is lifted upward from below, the raw materials in the container 32 can be efficiently stirred and mixed throughout. Since the configuration of the other parts of the dryer shown in FIG. 3 is common to the reduced-pressure drying apparatus of FIG.
The description of this part is omitted. Specific examples of the drying apparatus preferably used in the present invention having the above-described configuration include a Nauter mixer (manufactured by Hosokawa Micron), a ribocorn (manufactured by Okawara Seisakusho), and an SV mixer (manufactured by Shinko Pantech). No.

In the method for producing a toner according to the present invention, the external additive to be added to the colored polymer particles when dried with the above-described stirring and depressurizing dryer has an average particle diameter of preferably 0.2 μm. Below, more preferably 0.002-
It is preferable to use the one having a thickness of 0.2 μm, more preferably 0.01 to 0.2 μm. That is, when the average particle diameter of the external additive to be added is larger than 0.2 μm, the effect of improving the fluidity of the toner is reduced. On the other hand, if the average particle diameter is 0.002 μm or more, the external additives hardly aggregate, and the effect of improving the fluidity is more remarkably obtained. As a specific external additive, any one generally known as an external additive for a toner, such as a fluororesin powder, a fatty acid metal salt, and a metal oxide, can be used. For example, titanium oxide, silica, and alumina can be preferably used.

The toner obtained by the method for producing a toner according to the present invention has a finer particle size so that finer latent image dots can be faithfully developed and visualized in order to meet the demand for higher image quality. More specifically, it is most preferable that the toner has a weight average diameter of 4 μm to 8 μm measured by a Coulter counter and a number variation coefficient of 35% or less. That is, with a toner having a weight average diameter of less than 4 μm, a large amount of untransferred toner is generated on the photoreceptor or the intermediate transfer member due to poor transfer efficiency, which causes non-uniform unevenness of an image due to fog or poor transfer. Not preferred. Further, when the weight average diameter of the toner exceeds 8 μm, fusion to members tends to occur,
If the coefficient of variation of the number of toners exceeds 35%, the tendency is further increased, which is not preferable.

In the method for producing a toner of the present invention, a polymerizable monomer composition, which is a raw material for producing a toner and contains at least a polymerizable monomer and a colorant, is granulated and polymerized in an aqueous medium. Particles (colored polymer particles) are directly produced. At this time, it is preferable that a low softening point substance functioning as a release agent is contained in a toner production raw material. ASTM D34 is used as the low softening point substance at this time.
Compounds having a DSC main peak value of 40 to 90 ° C. measured according to 18-8 are preferred. That is, when the substance has a low softening point having a maximum peak of less than 40 ° C., the self-cohesive force of the low softening point substance is weakened, and as a result, the high-temperature offset property of the toner is weakened. Absent. On the other hand, if the substance has a low softening point whose maximum peak exceeds 90 ° C., the fixing temperature of the toner becomes high, and it becomes difficult to appropriately smooth the fixed image surface. Not preferred. Further, in the case of obtaining a toner by a direct polymerization method as in the present invention, since granulation and polymerization are performed in an aqueous system, if the temperature of the maximum peak value is high, a substance having a low softening point mainly occurs during granulation. It is not preferable because it precipitates and hinders the suspension system.

For the measurement of the temperature of the maximum peak value of the low softening point substance, for example, DSC-7 manufactured by Perkin Elmer Co., Ltd.
Can be used. In the present invention, the device was used, the temperature of the device detecting section was corrected using the melting points of indium and zinc, and the calorific value was corrected using the heat of fusion of indium. In the measurement, a sample for measurement was put in an aluminum pan, and a similar empty pan was set as a control, and the measurement was performed at a heating rate of 10 ° C./min.

The low-softening point substance having the above-mentioned properties which can be suitably used in the present invention includes, specifically,
Paraffin wax, polyolefin wax, Fischer-Tropsch wax, amide wax, higher fatty acid, ester wax and derivatives thereof, or graft / block compounds thereof can be used. In the present invention, particularly preferred is a form using an ester wax having at least one long-chain ester moiety having 10 or more carbon atoms represented by the following general structural formula. Use of such an ester wax has an effect on the high-temperature offset property without impairing the transparency of the OHP image. The structural formulas of representative compounds of specific ester waxes that can be preferably used in the present invention are shown below as general structural formulas, general structural formulas and general structural formulas.

[0037]

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[0038]

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[0039]

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In the method for producing a toner according to the present invention, among the ester waxes described above, further, a hardness of 0.
It is preferable to use those having a ratio of 5 to 5.0. Here, the ester wax has a hardness of 20 mm in diameter and a thickness of 5 mm after preparing a cylindrical sample, and then, for example, a dynamic ultra-micro hardness meter (DUH manufactured by Shimadzu Corporation).
This is a value obtained by measuring Vickers hardness using -200). The measurement conditions were as follows: a load of 0.5 g and a load speed of 9.67.
After being displaced by 10 μm under the condition of mm / sec, it was held for 15 seconds, and the resulting dent shape was measured to determine Vickers hardness. The hardness of the ester wax preferably used in the present invention shows a value of 0.5 to 5.0. In the case of a material having a low softening point having a hardness of less than 0.5, the pressure dependency and the process speed dependency of the fixing device increase, and the high-temperature offset effect tends to be insufficient. On the other hand, when the hardness exceeds 5.0, Also, since the storage stability of the toner is poor and the self-cohesive force of the release agent itself is small, the high-temperature offset tends to be insufficient similarly. Specific compounds suitable in the present invention include the following compounds.

[0041]

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[0042]

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[0043]

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[0044]

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In recent years, the necessity of full-color double-sided images has increased, but when forming double-sided images,
First, the toner-fixed image on the transfer paper formed on the surface is
The next time an image is formed on the back side, it may pass through the heating section of the fixing device again. Therefore, when forming a double-sided image rather than a single-sided image, consider the high-temperature offset property of the toner sufficiently. There is a need to. In the present invention, it is necessary to add a large amount of a low softening point substance for that purpose. Specifically, in the present invention, it is preferable to configure the toner such that a low softening point substance is added to the toner in an amount of 5 to 40% by weight. That is, if the addition is less than 5% by weight, sufficient high-temperature offset properties are not exhibited, and furthermore, at the time of fixing a double-sided image, the already formed backside image tends to exhibit an offset phenomenon. The content of the low softening point substance is 40% by weight.
In the case where the ratio is more than 1, the toner particles are apt to coalesce during granulation, and a particle having a wide particle size distribution is easily generated, which is not suitable for the present invention.

In the method for producing a toner of the present invention, the above-mentioned raw materials for producing a toner are used.
It is possible to directly produce toner particles (colored polymer particles) using the suspension polymerization method described in JP-A-6-10231, JP-A-59-53856 and JP-A-59-61842. It is possible. Furthermore, in the present invention, a so-called seed polymerization method in which a monomer is further adsorbed to the polymer particles once obtained and then polymerized using a polymerization initiator, can also be suitably used.

In the method for producing a toner according to the present invention, as described above, it is preferable that a large amount of a low softening point substance of 5 to 40% by weight is contained in the toner from the viewpoint of fixability. On the other hand, when the content of the low softening point substance increases, it becomes necessary to incorporate the low softening point substance into the outer shell resin. As a specific method for encapsulating the low softening point substance in the toner, the polarity of each material in the toner forming material in the aqueous medium is set to a lower softening point than the main monomer for constituting the binder resin. By setting the substance to be smaller, and adding a small amount of a polar resin or monomer, the low softening point substance becomes a shell resin (binder resin).
To obtain a toner having a so-called core-shell structure. In addition, the particle size distribution control and particle size control of the toner to be produced are performed by changing the type and amount of a poorly water-soluble inorganic salt or dispersant that acts as a protective colloid, mechanical device conditions,
For example, a toner having desired characteristics can be obtained by controlling the stirring conditions such as the peripheral speed of the rotor, the number of passes, the shape of the stirring blade, the shape of the container, and the solid content concentration in the aqueous solution.

In order to confirm that the low softening point substance used in the present invention is included in the toner, it is necessary to measure the tomographic plane of the toner particles. In this case, a specific method is used. There are the following methods. First, after the toner to be measured is sufficiently dispersed in a room temperature curable epoxy resin, the cured product obtained by curing for 2 days in an atmosphere at a temperature of 40 ° C. is subjected to ruthenium tetroxide and, if necessary, After staining with osmium oxide, a flaky sample is cut out using a microtome with diamond teeth, and the obtained sample is observed using a transmission electron microscope (TEM) to measure the tomographic morphology of the toner particles. I do. In this case, in order to provide contrast between the materials by utilizing a slight difference in crystallinity between the low softening point substance such as ester wax used in the present invention and the binder resin constituting the outer shell, It is preferable to use a ruthenium dyeing method. FIG. 4 shows a typical example of the tomographic morphology of the toner particles measured as described above for the toner obtained by the method for producing the toner of the present invention. As a result, as shown in FIG. 4, it was clearly observed that the low softening point substance was encapsulated in the outer shell resin.

In the method for producing a toner of the present invention, a polymerizable monomer composition, which is a raw material for toner production containing at least a polymerizable monomer and a colorant, is granulated and polymerized in an aqueous medium to obtain a colored polymer. A coalesced (polymerized toner particle) is produced, and the following polymerizable monomers can be used in this case. For example, styrene-based monomers such as styrene, o (m-, p-)-methylstyrene, m (p-)-ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acryl Propyl acid, (meth)
Butyl acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, (Meth) acrylate monomers such as diethylaminoethyl (meth) acrylate; butadiene,
Vinyl monomers such as isoprene, cyclohexene, (meth) acrylonitrile, and acrylamide are preferably used. These may be used alone or in general, on pages 139-192 of the published Polymer Handbook, Second Edition III.
These polymerizable monomers are appropriately mixed and used so that the theoretical glass temperature (Tg) described in (John Wiley & Sons) indicates 40 to 75 ° C. That is, if the theoretical glass transition temperature is less than 40 ° C., problems arise in terms of the storage stability of the toner and the durability stability of the developer, while if it exceeds 75 ° C., the fixing point increases,
In particular, in the case of a full-color toner, the color mixture of each color toner becomes insufficient, and the color reproducibility becomes poor.
Since the transparency of the OHP image is significantly reduced, it is not preferable from the viewpoint of forming a high quality image.

In the present invention, in order to incorporate the low softening point substance in the outer shell resin in a favorable state, in addition to the above-mentioned constituent materials of the outer shell resin, the raw materials for producing the toner may further include: It is particularly preferable to add a polar resin. Examples of the polar resin used in the present invention include a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer,
Saturated polyester resins and epoxy resins are preferably used. As the polar resin used in the present invention, it is particularly preferable to use a resin which does not contain an unsaturated group capable of reacting with a shell resin or a monomer in the molecule. That is, when the toner production raw material contains a polar resin having an unsaturated group, a crosslinking reaction occurs with the polymerizable monomer for forming the outer shell resin layer, so that the binder resin has a high molecular weight. It happens. In particular, when a full-color toner is used, the toner has an extremely high molecular weight, and is disadvantageous when mixing four-color toners, which is not preferable.

In the present invention, the following coloring agents can be used as a constituent material of the toner. As the black colorant, carbon black, a magnetic substance, and a black color tone using the following yellow / magenta / cyan colorant can be used. As a yellow colorant,
Compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 1
5, 17, 62, 74, 83, 93, 94, 95, 10
9, 110, 111, 128, 129, 147, 168
Etc. are preferably used.

As the magenta coloring agent, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds and the like can be used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 2,
3, 48; 2, 48; 3, 48; 4, 57; 1, 81;
1, 122, 144, 146, 166, 169, 17
7, 184, 185, 202, 206, 220, 22
1, 254 are particularly preferred.

As the cyan coloring agent, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds and the like can be used. Specifically, C.I. I.
Pigment Blue 1, 7, 15, 15: 1, 15: 2,
15: 3, 15: 4, 60, 62, 66, etc. can be particularly preferably used. These colorants can be used alone or as a mixture, or in the form of a solid solution. In the present invention, these colorants may be appropriately selected in terms of hue angle, saturation, brightness, weather resistance, OHP transparency, dispersibility in toner, and the like. The colorant may be added in an amount of 1 to 20 parts by weight based on 100 parts by weight of the binder resin. When a magnetic material is used as the black colorant, unlike the other colorants, it may be added in the range of 40 to 150 parts by weight with respect to 100 parts by weight of the binder resin.

In the method for producing a toner of the present invention, a charge control agent may be used as a raw material for producing a toner. As the charge control agent that can be used in the present invention, any of conventionally known charge control agents can be used. In particular, the color control agent is colorless and, when added, increases the charging speed of the toner and stabilizes the toner at a constant charge amount. It is preferable to use a charge control agent that can be maintained. Further, in the method for producing the toner of the present invention, since a direct polymerization method is used, it is particularly preferable to use a charge control agent which does not inhibit polymerization and has no solubilized substance in an aqueous medium.

Specific examples of the compound used as a charge control agent include negative compounds such as salicylic acid, naphthoic acid, metal compounds of dicarboxylic acids, sulfonic acids, high molecular compounds having carboxylic acids in their side chains, and boron compounds. Compounds, urea compounds, silicon compounds, carrick's arenes and the like can be used, and as the positive system, quaternary ammonium salts, polymer compounds having the quaternary ammonium salt in the side chain, guanidine compounds, imidazole compounds and the like are preferably used. Can be These charge control agents are preferably used in an amount of about 0.5 to 10 parts by weight based on 100 parts by weight of the binder resin. However, in the method for producing a toner of the present invention, the addition of a charge control agent is not essential. That is, in the case of the toner used in the two-component developing method, the toner is charged using frictional charging with the carrier, and in the case of the toner in the non-magnetic one-component blade coating developing method, the blade member and the sleeve member are used. The toner is charged by positively utilizing the frictional charging of the toner. Therefore, in these cases, it is not always necessary to include a charge control agent in the toner.

In the present invention, the following polymerization initiators may be used as raw materials for producing the toner.
For example, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2 ′ -Azobis-4-methoxy-2,
Azo or diazo polymerization initiators such as 4-dimethylvaleronitrile and azobisisobutyronitrile; peroxides such as benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide and lauroyl peroxide; An oxide polymerization initiator is used. The amount of these polymerization initiators varies depending on the desired degree of polymerization, but is generally added at a ratio of 0.5 to 20% by weight based on the polymerizable monomer. The type of the polymerization initiator varies slightly depending on the polymerization method, but may be used alone or in combination with reference to the 10-hour half-life temperature. Further, in the present invention, in order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor and the like can be further added to the raw material for producing the toner.

In the method for producing a toner of the present invention, particularly when suspension polymerization using a dispersion stabilizer is used, a dispersion stabilizer comprising the following inorganic compound and organic compound is added to an aqueous medium. Can be used. As the inorganic compound used at this time, for example, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, Examples thereof include calcium sulfate, barium sulfate, bentonite, silica, and alumina. Examples of the organic compound include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salts of carboxymethyl cellulose, polyacrylic acid and salts thereof, and starch. These can be used by dispersing them in an aqueous phase. It is preferable to use 0.2 to 20 parts by weight of these dispersion stabilizers based on 100 parts by weight of the polymerizable monomer.

When inorganic compounds are used among these dispersion stabilizers, of course, commercially available ones may be used as they are. However, in order to obtain fine particles, these inorganic compounds are used in a dispersion medium. May be generated. For example, when using tricalcium phosphate as a dispersion stabilizer, it is preferable to form a tricalcium phosphate by mixing and reacting an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high-speed stirring. Further, for fine dispersion of these dispersion stabilizers, 0.001 to 0.1 parts by weight of a surfactant may be used in combination. This is to promote the intended action of the dispersion stabilizer, and specific examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, and lauryl. Sodium silicate, potassium stearate, calcium oleate and the like.

In the toner manufacturing method of the present invention, the toner can be specifically manufactured by the following manufacturing method. First, in the polymerizable monomer for constituting the binder resin, a coloring agent, if necessary, a release agent comprising a low softening point substance, a charge control agent, a polymerization initiator and other additives, A homogenizer, an ultrasonic disperser or the like is used to prepare a monomer system (polymerizable monomer composition) uniformly dissolved or dispersed. An aqueous phase (aqueous medium) containing a dispersion stabilizer prepared in advance using the obtained polymerizable monomer composition
Inside, it is dispersed with an ordinary stirrer or a clear mixer, a homomixer, a homogenizer or the like. Preferably, the granulation is performed by adjusting the stirring speed, the stirring time, and the like so that the monomer droplets have the desired size of the toner particles. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. The polymerization temperature is 40 ° C. or higher, generally 50 to 90.
It is preferred to carry out the polymerization at a temperature of ° C. Further, the temperature may be raised in the latter half of the polymerization reaction, and further, the second half of the reaction or the end of the reaction to remove unreacted polymerizable monomers and by-products which cause odor at the time of fixing the toner. Later, a part of the aqueous medium may be distilled off. In the suspension polymerization method, it is generally preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer system. After the completion of the reaction, the generated colored polymer particles (toner particles) are collected by washing and filtration, and the wet colored polymer particles are dried by the drying method described above to obtain a toner having an external additive. obtain.

In the present invention, the external additive obtained as described above is added, and the dried toner particles are further provided with a mechanical impact to adjust the state of attachment of the external additive to the toner particles. Is preferred. Specifically, it is preferable to adjust the state of attachment of the external additive to the toner particles by applying a mechanical impact force using a dry mixer such as a Henschel mixer. More specifically, the peripheral speed of the high-speed rotating blades of the Henschel mixer and the processing time are adjusted to adjust the state of attachment of the external additive to the toner particles. Also, at this time,
If necessary, it is preferable to add the above-mentioned external additive, or to add another external additive such as a charge-imparting agent or an abrasive to perform the treatment at the same time.

Hereinafter, various measurement methods used in the present invention will be listed. <Measurement of Residual Amount of Polymerizable Monomer Remaining in Toner Particles> The remaining amounts of the polymerizable monomer and organic solvent remaining in the toner particles were determined by dissolving 0.2 g of the toner in 4 ml of THF. Each was measured by an internal standard method under the following conditions by gas chromatography. (GC conditions) ・ Measuring device: Shimadzu GC-15A (with capillary) ・ Carrier: N ₂ , 2 kg / cm ² 50 ml / min ・ Split ratio 1:60, linear velocity 30 mm / sec ・ Column: ULBONHR-1 50m × 0.25mm ・ Sample amount: 2μl ・ Marked substance: toluene

<Measurement of Particle Size Distribution of Toner> The particle size distribution of the toner can be measured by various methods. In the present invention, the measurement was performed using a Coulter counter. As a measuring device, a Coulter Counter TA-II type (manufactured by Coulter) is used, and an interface (manufactured by Nikkaki) for outputting a number average distribution and a volume average distribution, and a CX-1 personal computer (manufactured by Canon Inc.) are connected. It was measured. The electrolyte is 1% sodium chloride
An aqueous NaCl solution was prepared and used. As a specific measurement method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and a measurement sample is placed in the solution for 2 to 2 ml.
Add 0 mg to prepare a sample for measurement. The electrolytic solution in which this sample was suspended was subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the above-mentioned Coulter counter TA-II was used.
Depending on the mold, the particle size distribution of the particles of 2 to 40 μm was measured based on the number, using a 100 μm aperture as the aperture, and then various values were obtained.

[0063]

The present invention will be described more specifically below with reference to examples and comparative examples of the present invention. (Example 1) First, 0.10 parts by weight of ion-exchanged water was added to 710 parts by weight.
After adding 450 parts by weight of a 1 mol / liter Na ₃ PO ₄ aqueous solution and heating to 60 ° C., the mixture was stirred at 3,500 rpm using a clear mixer (manufactured by M Technique Co., Ltd.). To this, 68 parts by weight of a 1.0 mol / liter CaCl ₂ aqueous solution was added, and Ca ₃ (PO ₄ ) ₂ as a dispersion stabilizer was added.
Was finely dispersed to obtain an aqueous medium.

On the other hand, as a dispersoid system, first, of the following formulation, grafted carbon black, salicylic acid metal compound and 100 parts by weight of styrene monomer were dispersed for 3 hours using an attritor (manufactured by Mitsui Miike Kakoki). A colorant dispersion was obtained. Next, to this colorant dispersion liquid, all the remaining components of the following formulation were added, and the mixture was heated to 60 ° C. and dissolved and mixed for 30 minutes. Into this, 10 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was dissolved to prepare a polymerizable monomer composition. -Styrene monomer 165 parts by weight-n-butyl acrylate 35 parts by weight-Grafted carbon black 15 parts by weight-Saturated polyester 15 parts by weight-Metal salicylate compound 2 parts by weight-The following compound (1) (peak temperature in DSC = 59) 0.4 ° C, Vickers hardness 1.5) 25 parts by weight

[0065]

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The polymerizable monomer composition obtained above was charged into the aqueous dispersion medium prepared above, and granulated for 15 minutes while maintaining the rotation speed. Then, the stirrer was changed from a high-speed stirrer to a propeller stirring blade, and the internal temperature was raised to 80 ° C.
The polymerization was continued for 10 hours at 0 revolutions / minute. After polymerization,
The slurry was cooled, diluted hydrochloric acid was added, and Ca ₃ (PO ₄ ) ₂ as a dispersion stabilizer was dissolved, followed by filtration and washing with water.
Colored polymer particles in a wet state having a water content of 20% were obtained.

After crushing the wet colored polymer particles obtained above, a continuous instantaneous flash dryer (flash dryer FJD) is used.
-4: manufactured by Seishin Enterprise Co., Ltd.). The drying conditions were as follows: air at 90 ° C. was blown in at a linear velocity of 16.5 m / sec, and the wet colored polymer particles were weighed at 20 kg / h.
r. Was supplied continuously. The water content of the colored polymer particles (hereinafter, referred to as primary dried toner particles) after the completion of the primary drying was 0.1%. Further, as a result of measuring the amount of the polymerizable monomer remaining in the toner particles at this time, the content of the polymerizable monomer in the toner particles was 680 ppm. Further, no lumps were generated due to aggregation of the toner, and the passing rate through a sieve having an opening of 149 μm was 97%. Here, the pass rate is a value obtained by the following equation.

[0068]

(Equation 1)

Next, the removed primary dry toner particles 30
kg and 240 g of titanium oxide having an average particle size of 0.05 μm as an external additive were put into a 100-liter Nauter-type vacuum dryer (NXV-1: manufactured by Hosokawa Micron Corporation), and dried under reduced pressure while stirring. went. As drying conditions, a jacket heating temperature of 50 ° C., a degree of vacuum of 2 to 5 kPa,
Drying was performed for 2 hours while supplying nitrogen gas from the lower part at 5.0 N liter / min. After the drying was completed, the discharge of the dry toner particles from the outlet was good, and the whole amount could be easily taken out. Further, when the inside of the dryer was visually observed, adhesion of toner to the wall surface and the stirring blade in the dryer was hardly observed. Further, the content of the polymerizable monomer remaining in the toner particles taken out at this time was 15 ppm. Further, the passing rate through a sieve having an opening of 149 μm is 97.
%, Which was good.

The weight average particle diameter of the toner obtained as described above was 6.8 μm. FIG. 4 shows a schematic view of a tomographic photograph of the toner particles using transmission electron microscopy for the toner. The toner has a structure in which compound (1), which is a substance having a low softening point, is covered with a shell resin. Was. Further, based on 100 parts by weight of the toner particles obtained above, an average particle size of 0.03
0.8 parts by weight of hydrophobic silica having a particle size of 0.8 μm was added and externally added and mixed with a Henschel mixer to obtain a toner of this example.

Further, 95 parts by weight of an acryl-coated ferrite carrier was mixed with 5 parts by weight of the toner obtained above to obtain a two-component developer. Using the obtained developer, it was mounted on a remodeled machine of a color copier CLC500 manufactured by Canon Inc., and an image-drawing test was performed under an environment of 23 ° C./65% RH. As a result, even at the endurance of 10,000 sheets, there was no change in the image density at the initial stage and after the endurance, and a high-quality image with no hollow was obtained. In addition, problems such as toner fusion and memory ghost did not occur on the photoconductor made of an organic semiconductor. Further, a double-sided image was formed using plain paper as a transfer material, but no occurrence of offset was recognized on both the front and back surfaces of the transfer material. Further, the same image-drawing test was performed in a high-temperature and high-humidity environment of 30 ° C./80% RH, and similar results were obtained.

(Example 2) 30 kg of primary dried toner particles dried by the continuous flash drying device obtained in Example 1,
150 g of titanium oxide having an average particle size of 0.05 μm was added in a capacity of 1
00 liter Nauter type vacuum dryer (NXV-1
(Type: manufactured by Hosokawa Micron Corporation)
Drying under reduced pressure for an hour was performed. After the drying was completed, the discharge of the dry toner particles from the outlet was good, and the whole amount could be easily taken out. When the inside of the dryer was examined, almost no toner adhesion was observed on the wall surface inside the dryer and on the stirring blade. When the remaining polymerizable monomer was measured for the removed toner particles, the content was 18 ppm. The passing rate through a sieve having an opening of 149 μm was 96%.

With respect to 100 parts by weight of the obtained toner particles,
0.8 parts by weight of hydrophobic silica having an average particle size of 0.03 μm,
0.3 parts by weight of titanium oxide having an average particle diameter of 0.05 μm was added and externally added and mixed with a Henschel mixer to obtain a toner of this example. Further, for 5 parts by weight of this toner,
95 parts by weight of an acrylic-coated ferrite carrier were mixed to prepare a two-component developer. Using the developer obtained above, the same image evaluation as in Example 1 was performed. As a result, a good image was obtained as in Example 1.

(Comparative Example 1) The same reduced pressure dryer (NXV-X) as in Example 1 was used, except that no external additive was added to 30 kg of the primary dried toner particles dried by the continuous flash dryer obtained in Example 1.
(Type 1), jacket heating temperature 50 ° C, degree of vacuum 2
Vacuum drying was performed while stirring at で 5 kPa for 2 hours. The content of the polymerizable monomer remaining in the dried toner particles was 250 ppm. Then, drying under reduced pressure was performed while stirring similarly for 2 hours. After the drying was completed, the dried toner particles were discharged from the outlet. As a result, toner adhered to the wall surface of the dryer and the agitating blade, and about 3 kg remained in the dryer, and a discharging operation was required. The content of the polymerizable monomer remaining in the removed toner particles is 30 p.
pm. The passing rate through a sieve having an opening of 149 μm was 95%. 0.8 parts by weight of hydrophobic silica having an average particle diameter of 0.03 μm and 0.8 parts by weight of titanium oxide having an average particle diameter of 0.05 μm are added to 100 parts by weight of the toner particles first taken out of the dryer. The mixture was externally added and mixed with a Henschel mixer to obtain a toner of this comparative example. Further, 95 parts by weight of an acryl-coated ferrite carrier was mixed with 5 parts by weight of the obtained toner to obtain a two-component developer. Using this two-component developer, the same image evaluation as in Example 1 was performed. As a result, a good image was obtained as in Example 1. However, after completion of drying under reduced pressure, only the toner particles remaining in the dryer were taken out, a two-component developer was prepared in the same manner as above, and the same image formation evaluation as above was performed. Under an environment of ° C / 80% RH, a decrease in image density was observed.

(Comparative Example 2) Primary dried toner particles (moisture content: 0.1%) dried by the continuous flash dryer obtained in Example 1.
1%, amount of polymerizable monomer remaining in toner particles 68
0 ppm) was used as toner particles without drying under reduced pressure. Then, as in Comparative Example 1, 0.8 parts by weight of hydrophobic silica having an average particle diameter of 0.03 μm and 0.8 parts by weight of titanium oxide having an average particle diameter of 0.05 μm were added to 100 parts by weight of the toner particles. Was added and mixed externally with a Henschel mixer to obtain a toner of this comparative example. Further, 95 parts by weight of an acryl-coated ferrite carrier was mixed with 5 parts by weight of the toner to obtain a two-component developer. Using the obtained two-component developer, an image forming test similar to that in Example 1 was performed. As a result, solid white spots due to poor transfer occurred from about 500 sheets, and the image density was reduced from about 2,000 sheets. Decreased. Furthermore, 30 ° C / 80% RH
In the test under the environment, the image defect occurred due to fusion of the toner to the photoreceptor on about 1,500 sheets.

(Comparative Example 3) Water content of 20% obtained in Example 1
After crushing about 30 kg of wet colored polymer particles of
Vacuum drying was performed while stirring using a 1 liter Nauter type vacuum dryer (Model NXV-1). Drying was performed at a jacket heating temperature of 50 ° C. and a degree of vacuum of 2 to 5 kPa for 6 hours. At this time, the water content of the toner particles was measured to be 0.3%. Further, the content of the polymerizable monomer remaining in the toner particles was 320 ppm, and the passing ratio through a sieve having an opening of 149 μm was 78%. After the dried toner particles are discharged, about 4
kg of the toner adhered, and a part of the toner adhered to the stirring blade and the apparatus wall. The obtained toner particles were pulverized, and thereafter the same operation as in Comparative Example 2 was performed to obtain a two-component developer. Using the obtained two-component developer, the same image-drawing test as in Example 1 was carried out.
Solid white spots due to transfer failure occurred on about
The image density was reduced from about 00 sheets. In addition, 30
In a test in an environment of ° C./80% RH, an image defect occurred due to fusion of the toner to the photoreceptor on about 3,000 sheets.

(Example 3) First, the same aqueous dispersion medium as in Example 1 was prepared. On the other hand, as a dispersoid system, C.I. I. Pigment Red 122, salicylic acid metal compound and 100 parts by weight of styrene monomer were dispersed for 3 hours using an attritor (manufactured by Mitsui Miike Kakoki Co., Ltd.) to obtain a colorant dispersion. Next, to this colorant dispersion liquid, all the remaining components of the following formulation were added, and the mixture was heated to 60 ° C. and dissolved and mixed for 30 minutes. Into this, 10 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was dissolved to prepare a polymerizable monomer composition. -Styrene monomer 170 parts by weight-2-ethylhexyl acrylate 30 parts by weight-C.I. I. Pigment Red 122 10 parts by weight-Saturated polyester 20 parts by weight-Metal salicylate compound 3 parts by weight-Compound (1) used in Example 1 30 parts by weight

The polymerizable monomer composition obtained above was charged into the aqueous dispersion medium and granulated for 15 minutes while maintaining the rotation speed. Thereafter, the stirrer was changed from a high-speed stirrer to a propeller stirring blade, the internal temperature was raised to 80 ° C., and polymerization was continued at 50 rpm for 10 hours. After the polymerization, the slurry was cooled, diluted hydrochloric acid was added, and Ca ₃ (PO ₄ ) ₂ was dissolved.
After filtration and washing with water, wet colored polymer particles having a water content of 23% were obtained. Next, after the wet colored polymer particles having a water content of 23% were crushed, primary drying was performed using a continuous instantaneous flash dryer (flash dryer FJD-4) in the same manner as in Example 1. As drying conditions, air at 90 ° C. was blown at a linear velocity of 16.5 m / sec, and the wet colored polymer particles were continuously supplied at 35 kg / hr. After the completion of the primary drying, the water content was measured and found to be 0.1%. Further, when the amount of the polymerizable monomer remaining in the toner particles at this time was measured, the content of the polymerizable monomer in the toner particles was 520 ppm. There was no generation of lumps due to aggregation of the toner, and the passing rate through a sieve having an opening of 149 μm was 96%.

Next, the removed primary dried toner particles 20
kg of hydrophobic silica 200 having an average particle size of 0.005 μm.
g of a 50-liter ribocorn vacuum dryer (RD)
-50 type: manufactured by Okawara Seisakusho Co., Ltd.), while stirring, the jacket heating temperature is 50 ° C., and the degree of vacuum is 0.7 to 2 kP.
In a, drying under reduced pressure was performed for 2 hours. After the drying was completed, the discharge of the dry toner particles from the outlet was good, and the whole amount could be easily taken out. Also, on the wall inside the dryer and on the stirring blades,
Almost no toner adhered. The content of the polymerizable monomer remaining in the removed toner particles was 25 ppm. The passing rate through a sieve having an opening of 149 μm was 96%. The weight average particle size of the toner was 6.3 μm. FIG. 4 shows a schematic view of a tomographic photograph of the toner.
The compound showed a structure in which the compound (1), which is a low softening point substance, was covered with a shell resin.

With respect to 100 parts by weight of the obtained toner particles,
0.5 parts by weight of the hydrophobic silica having an average particle diameter of 0.005 μm was added and externally added and mixed with a Henschel mixer to obtain a toner of this example. Using this toner as a one-component developer, a modified machine of a color laser jet printer, color laser shot-2030 manufactured by Canon Inc.
An image-drawing test was performed in an environment of ° C / 65% RH. As a result, even at 5,000 sheet durability, there was no change in the image density at the initial stage and after the endurance, and a high-quality image with no hollow was obtained. In addition, there were no problems such as toner fusion and memory ghost on the photoconductor made of an organic semiconductor.
When an image was formed on the OHP sheet, an image having good transparency was obtained.

(Example 4) 23% of water content obtained in Example 3
Approximately 40 kg of wet colored polymer particles of the formula (1) are pulverized, and then crushed.
Drying was performed using. As drying conditions, air at 50 ° C. was blown at a linear velocity of 0.4 m / sec, and after 2 hours, the toner was taken out. The primary dried toner after the primary drying was measured, and the water content was 0.3%. At this time, the content of the polymerizable monomer remaining in the toner particles was 380 ppm, but no lumps were generated due to aggregation of the toner, and the passing rate through a sieve having an opening of 149 μm was 96%.
Met.

Next, 30 kg of the primary dry toner particles obtained above and hydrophobic silica having an average particle diameter of 0.005 μm were combined with a 100-liter Nauter-type vacuum dryer (N
XV-1 type: manufactured by Hosokawa Micron Corporation) and dried under reduced pressure for 2 hours while stirring. After the drying was completed, the discharge of the dry toner particles from the outlet was good, and the whole amount could be easily taken out. Also, almost no toner adhered to the wall surface inside the dryer or the stirring blade. The content of the remaining polymerizable monomer in the removed toner particles was measured and found to be 20 ppm. The passing rate through a sieve having an opening of 149 μm was 96%. With respect to 100 parts by weight of the toner particles obtained above, the average particle diameter was 0.005 μm.
m of hydrophobic silica was added and mixed with a Henschel mixer to obtain a toner of this example. Further, when the obtained toner was used as a one-component type developer and the image formation evaluation was performed in the same manner as in Example 3, a good image was obtained as in Example 3.

(Comparative Example 4) 30 kg of the primary dried toner particles dried by the continuous flash dryer obtained in Example 3 was used.
Without adding an external additive, using the same reduced-pressure drier (RD-50 type) as used in Example 3, a jacket heating temperature of 50 was used.
Drying under reduced pressure was performed for 4 hours at a temperature of 0.7 ° C. and a degree of vacuum of 0.7 to 2 kPa. After the drying was completed, the dried toner particles were discharged from the outlet. As a result, toner adhered to the wall surface of the dryer and the agitating blade, and about 2 kg remained in the dryer, and a discharging operation was required. The content of the polymerizable monomer remaining in the removed toner particles was 80 ppm, and the
The passability through a μm sieve was 90%.

Comparative Example 5 23% water content obtained in Example 3
After crushing about 40 kg of the wet colored polymer particles of the above, drying was performed using a fluidized bed dryer (FBS-5 type: manufactured by Okawara Seisakusho). As drying conditions, air at 50 ° C. and a linear velocity of 0.4
Blowing was performed at m / sec, and after 4 hours, the toner was taken out and drying was completed. When the water content of this toner was measured,
0.1%, and the content of the polymerizable monomer remaining in the toner particles was 180 ppm. However, lumps were generated due to aggregation of the toner, and the passing rate through a sieve having an opening of 149 μm was 85%. Also, on the inner wall of the dryer,
A toner adhesion layer was observed. When the moisture content was measured by taking out the toner adhesion layer, the moisture content was 0.1%, but the content of the polymerizable monomer remaining in the toner particles was 320 ppm. With respect to 100 parts by weight of the toner particles taken out of the dryer, the average particle diameter was 0.00
1.5 parts by weight of 5 μm hydrophobic silica was added and mixed with a Henschel mixer to obtain a toner of this comparative example. Further, using this toner as a one-component developer,
The same image-drawing test was performed. As a result, the durability 1,50
Solid white spots due to poor transfer occurred from about 0 sheets, and image defects due to fusion of toner to the photoreceptor occurred at about 4,500 sheets under an environment of 30 ° C./80% RH.

[0085]

As described above, according to the present invention,
Wet toner particles obtained by the direct polymerization method,
Provided is a method for producing a toner capable of easily obtaining a toner having excellent characteristics by drying uniformly and efficiently in a short time while removing unreacted polymerizable monomers.
According to the present invention, there is provided a method for producing a toner capable of obtaining a toner capable of forming a high-quality image without causing image defects due to unreacted polymerizable monomers remaining in the toner. .

[Brief description of the drawings]

FIG. 1 shows an example of a system of an apparatus for instantaneously drying an object to be dried (wet particles or slurry) in the form of powder and granules in a hot air stream and sending it in parallel to a high-speed hot air stream. FIG.

FIG. 2 is a schematic sectional view showing an example of a reduced-pressure drying apparatus and an apparatus system used in the present invention.

FIG. 3 is a schematic sectional view showing an example of a reduced-pressure drying apparatus and an apparatus system used in the present invention.

FIG. 4 is a schematic view showing a cross section of the toner of Example 1.

[Explanation of symbols]

 1: Hot air generator 2: Air flow drying tube 3: Air flow dispersion unit 4: Air flow outlet 5: Cyclone 6: Drying material supply device 7: Dry product take-out port 10: Bag filter 11: Jacket 12: Steam supply port 13: Cooling water supply port 14: discharge port 15: pump 16: manhole 17: steam inlet 18: accumulator 19: boiler 20: cold trap 21: partition plate 22: filter cloth 23: discharge port 24: cleaning nozzle 25: compressor 26 : Filter 28: Vacuum pump 29: Pump 30: Gas inlet 31: Mixer 32: Vessel 33: Driving device 34: Driving arm 35: Stirring member 36: Material supply port 37: Exhaust port 38: Outlet 39: Take out Valve 40: Ribbon blade type stirring member

Claims (8)

[Claims] 1. A polymerizable monomer composition containing at least a polymerizable monomer and a colorant, polymerized in an aqueous medium,
After the colored polymer particles are formed, the wet colored polymer particles obtained by washing and dehydration are dried using hot air to obtain a colored weight having a water content of 0.1% or more and less than 1.0%. After the combined particles, an external additive is added to the colored polymer particles, and while stirring these, the remaining amount of the unreacted polymerizable monomer remaining in the colored polymer particles is reduced to 200 ppm or less. A method for producing a toner, comprising drying under reduced pressure until a toner is obtained. 2. The drying method according to claim 1, wherein the drying using hot air is drying while dispersing the colored polymer particles in a wet state in a hot air flow into powder and granules, and sending the particles in parallel with the hot air flow. Manufacturing method of toner. 3. The method for producing a toner according to claim 1, wherein the drying using hot air is a drying in which a fluidized layer is formed by suspending and suspending wet colored polymer particles. 4. The method of claim 1, wherein the drying under reduced pressure is performed under a gas supply.
The method for producing a toner according to claim 1. 5. The drying under reduced pressure, the pressure in the dryer is 13 kPa.
The method for producing a toner according to claim 4, wherein the method is performed while supplying a gas in an amount to be held below. 6. An external additive having an average particle size of 0.002 to 0.5.
The method for producing a toner according to claim 1, wherein the thickness is 2 μm. 7. The toner according to claim 1, wherein the toner particles contain a low softening point substance at a ratio of 5 to 40% by weight, and the low softening point substance is encapsulated in an outer shell resin layer. Any one
13. The method for producing a toner described in the above section. 8. The method according to claim 7, wherein the low softening point substance is an ester wax having at least one long-chain ester moiety having 10 or more carbon atoms.