JP2004246334A - Manufacturing method of electrophotographic toner - Google Patents

Abstract

An object of the present invention is to provide a method for producing a toner for electrophotography, in which charge control agent particles are uniformly fixed at least in the vicinity of the surface of toner base particles and are difficult to separate.
A rotating stirrer having at least a rotating body having stirring blades and a jacket for flowing a refrigerant to a wall to control the temperature, and using a fluidized stirring type mixing device having a spherical mixing container shape, wherein the stirring blades are 65-65. By rotating at a stirring speed (peripheral speed) of 115 m / s, a toner base powder composed of at least a binder resin, a colorant and a release agent and a charge controlling agent are stirred and mixed, and the surface of the toner base powder is mixed. A method for producing an electrophotographic toner by fixing a charge control agent to a toner.
[Selection diagram] FIG.

Description

  The present invention relates to a method for producing an electrophotographic toner, and in particular, a charge control agent for surface treatment is injected into a toner surface containing a thermoplastic resin as a main component and a release agent that is a low-melting substance. And a technique for reliably and efficiently immobilizing.

  2. Description of the Related Art Conventionally, high image quality has been pursued in image forming apparatuses such as copying machines and printers. For this reason, toner for image formation has been reduced in size, and it has been strongly required to ensure fluidity and uniform charging of the toner. For this purpose, various methods have been proposed as methods for adding, mixing and efficiently adhering various external additives to the surface of toner particles.

For example, a method of forming a film layer of a surface treatment agent using mechanical thermal energy mainly including an impact force (for example, see Patent Document 1), a method of firmly attaching the surface treatment agent by instantaneous surface heating treatment (for example, (See Patent Literature 2) A method of producing a surface-treated resin in a spherical container having two-stage blades (for example, see Patent Literature 3), and a method of removing unadhered matter after mixing and adhering fine powder (for example, Patent Literature 4) See, for example).
In other words, according to these known techniques, in order to strongly adhere the surface treating agent to the surface of the thermoplastic resin, it is necessary to increase the product temperature and soften the resin surface to increase the impact force, or to actively heat the resin surface. This suggests that there is a method of adhering without using an impact force, and that non-adhered matter is likely to be present.

Further, in recent years, low temperature fixing of electrophotographic toner has progressed, and a binder resin having a low glass transition temperature has been favorably used as a binder resin constituting the toner. Further, a low melting point substance is contained in the toner for electrophotography, so that the toner has releasability from the image forming apparatus.
When agitating and mixing to adhere an external additive to toner base particles containing a low melting point substance and a binder resin having a low glass transition temperature, the toner or the low melting point substance in the toner does not melt. If the treatment is not performed at the temperature, the low-melting-point substance elutes and the physical properties of the toner change. In addition, since an aggregate is formed by fusion, new classification and removal are required, which is not efficient.

Focusing on the glass transition temperature of the resin, a method of stirring and mixing at a relatively low temperature to adhere inorganic fine particles to the toner surface has been proposed, and a technique of stirring and mixing with a Henschel mixer using a vertical cylindrical processing tank has been proposed. (For example, see Patent Document 5).
In order to improve the fluidity and to ensure the fluidity by attaching a surface treatment agent to the toner as a fluidity aid, it is necessary to secure the irregularities due to the additives on the particle surface. Since a moderate impact force is required to obtain the adhering force, a vertical cylindrical processing tank in which the peripheral speed of the rotating blades is relatively high as compared with other mixers as described in Patent Document 5 is used as mixing and stirring. It can be carried out by a method using a Henschel mixer or a high-speed mixer used.

However, in the case of a surface treatment agent for the purpose of charge control, it is necessary not only to adhere to the toner, but also to bury part or all of the surface treatment agent uniformly on the surface of the toner particles and to firmly fix the surface treatment agent. In order to do this, the mixing must be performed at a stirring speed that gives a sufficient impact force.
If toner having insufficient fixation of the charge control agent is present, uniform triboelectricity cannot be obtained, causing image fouling called fog.
To perform a surface treatment for charge control on a toner containing a low melting point material and a binder resin having a low glass transition temperature, a low temperature within a range where the low melting point substance does not flow out, and However, it is necessary to give a sufficient impact force for fixing.

  In order to perform low-temperature treatment within a range in which the low-melting-point substance does not flow out, there is a method of reducing the charged amount, but there is a disadvantage that productivity is deteriorated. As another method, there is a method of flowing a coolant at a temperature that can sufficiently lower the temperature of the processed powder into the jacket of the mixing device. However, when the inside of the mixing device is filled with the atmosphere, a problem of dew condensation inside the mixing device occurs. However, the object to be treated aggregates, and it becomes impossible to uniformly fix the mixing / charging control agent.

Mixing devices such as Henschel mixers and high-speed mixers have a flat cylindrical stirring bottom, so high-speed stirring causes turbulence inside the device and uneven behavior of the powder, as shown in Fig. 1. It becomes. As a result, there is a disadvantage that the powder not only stays at the bottom of the apparatus but also easily adheres to the cylindrical wall surface. Further, since the peripheral speed of the rotating blade is 40 m / sec at the maximum in practical use, it is actually difficult to sufficiently fix the peripheral speed in a Henschel mixer or a high-speed mixer.
A hybridizer is known as a stirring and mixing device capable of rotating at a higher speed than these mixers (for example, see Patent Document 6).
When this stirring and mixing device is used, it is possible to sufficiently fix the processing agent to the toner base particles. However, since the toner base particles collide with the device wall due to irregularities on the wall surface and rotate at high speed, and generate heat, the toner base particles are heated. Some of the particles may be fused and aggregated, or the release agent may be exposed, and the physical properties of the toner may be changed. In addition, since it is intended to mix two or more kinds of particles due to heat generation, it does not have a sufficient cooling mechanism.
Therefore, in order to treat toner base particles containing a low melting point substance and a binder resin having a low glass transition point temperature in a low temperature range in which the low melting point substance does not flow, it is necessary to extremely reduce the amount of treatment. , Practically can not be used.

As described above, in order to process a toner composed of a binder resin having a low melting point and a low glass transition point temperature in a low temperature range in which the low melting point substance does not flow out, a stirring and mixing process is performed by a conventional mixer. Insufficiently, the surface treatment state of each toner particle varies, and the entire surface of the toner base particles becomes a mixture of the treated toner particles and a part of the treated toner particles, and the triboelectric charge amount of each particle is uneven. Therefore, there is a disadvantage that image fouling called fog occurs at the time of copying, and the amount of toner collected without contributing to image formation increases.
In addition, in the case of a toner having a weak surface treatment agent attached thereto, the surface treatment agent is easily separated from the toner during use, which causes problems such as damaging the photoreceptor and deteriorating the function of the developer due to carrier spent. appear.

As a method for preparing toner base particles composed of at least a thermoplastic resin, a colorant and a release agent, for example, melt-kneading a thermoplastic resin, a colorant and a release agent and necessary various additives, followed by pulverization and classification Or a polymerization method in which a thermoplastic resin, a colorant, and a release agent are dispersed as oil droplets in a solvent and a polymerization reaction is performed.
In the polymerization method, it is difficult to incorporate the charge control agent into the oil droplets. Therefore, it is indispensable as a technique for uniformly fixing the charge control agent to the resin powder produced by the polymerization method and finishing the toner with high reliability.
On the other hand, with respect to a toner manufactured by kneading and pulverizing a conventional toner material integrally, a charge control agent, which is one of the internal additives and is an expensive material, exerts a charging function by being present on the toner surface. The presence of the charge control agent as a surface treatment agent on the surface can provide a necessary function with a small amount of the charge control agent, and is expected to reduce costs.
There has been a demand for an efficient production method of toner that can sufficiently exhibit its function by allowing a charge control agent to be present mainly in the vicinity of the surface of toner base particles containing a low-melting substance. It is the fact that we have reached today.

JP-A-63-85756 JP-A-10-10781 JP-A-10-95855 JP-A-63-139366 JP 2000-267354 A JP-A-5-34971

An object of the present invention is to provide a method for producing a toner for electrophotography, in which charge control agent particles are uniformly fixed at least in the vicinity of the surface of toner base particles containing a release agent as a low-melting substance and are difficult to be separated.
Another object of the present invention is to prevent the low-melting substance from further fusing to the surface of the toner base containing the releasing agent, which is a low-melting substance, or to agglomerate the toners, and to fix and fix the charge controlling agent. To provide a method for producing a toner for electrophotography.
It is a further object of the present invention to provide a method for efficiently producing an electrophotographic toner having a uniform charge amount and no deterioration of a developer in consideration of productivity.

  The object of the present invention is to use (1) a fluid-stirring type mixing apparatus having at least a rotating body having stirring blades and a jacket for flowing a refrigerant to a wall to adjust the temperature and having a spherical mixing vessel shape. By rotating the stirring blade at a stirring speed (peripheral speed) of 65 to 115 m / s, the toner base powder including at least the binder resin, the colorant, and the release agent is stirred and mixed with the charge control agent. A method for manufacturing a toner for electrophotography by fixing a charge control agent to the surface of the toner base powder, wherein a refrigerant having a temperature equal to or lower than the installation environment temperature is flowed into the jacket and the stirring blade, and the mixture is supplied into the mixing device. Tg-10> T> Tg-35 (Tg: glass transition temperature of resin powder (° C.)) while supplying dry gas having a dew point temperature lower than the refrigerant temperature to forcibly replace air in the mixing device. It will be a relationship A method for producing an electrophotographic toner characterized by stirring at an ambient temperature (T ° C.) in a simple apparatus ”, (2)“ A stirring blade in the fluid stirring type mixing apparatus has a stirring speed of 70 to 100 m / s ( (3) The method for producing an electrophotographic toner according to the item (1), wherein the charge controlling agent is fixed by stirring at a peripheral speed). The production of the toner for electrophotography according to the above item (1) or (2), wherein the toner base powder and the charge control agent are stirred while maintaining an arbitrary constant temperature of −5 to 15 ° C. Method (4), wherein the dry gas used to forcibly replace the air inside the mixing device is introduced from the rotary shaft of the stirring blade and the rotary shaft seal of the mixing tank. The method for producing the electrophotographic toner according to any one of the items (3) to (3) ” (5) The above-mentioned items (1) to (4), wherein the gas which has been forcibly replaced from the inside of the mixing device is discharged from a hollow interior pipe vertically penetrating into the inside from the upper portion of the mixing device. Item 6. A method for producing an electrophotographic toner according to any one of the above items), (6) "Dry gas having a relationship of gas dew point temperature <jacket refrigerant temperature-5 ° C is used to replace air inside the mixing device." The method for producing an electrophotographic toner according to any one of the above items (1) to (5) ", (7)" a refrigerant at room temperature or higher can flow through the jacket of the mixing device. (8) The method for producing an electrophotographic toner according to any one of (1) to (6), wherein the stirring blades are radially positioned impellers. Any one of the above items (1) to (7) (9) The method according to (1), wherein the stirring and mixing amount of the toner base powder is 0.2 to 0.6 times the container amount used for mixing. (1) The method for producing a toner for electrophotography according to any one of the above items (1) to (8) ", (10) wherein the average particle size of the toner base powder is 3 to 7.5 m. (11) The method for producing an electrophotographic toner according to any one of the above items (1) to (9), (11) wherein the primary particle diameter of the charge control agent is 5 nm to 300 nm. The method for producing an electrophotographic toner according to any one of the above items (1) to (10) ".

In the production method of the present invention, by using a fluid stirring type mixing apparatus having a spherical shape in a mixing vessel, and mixing at an appropriate temperature range based on Tg and at a high stirring speed, compared with the conventional method, In addition, the charge control agent can be efficiently fixed to the core resin powder, and the productivity can be improved by setting the temperature of the medium to the jacket of the mixing device and the dew point temperature of the gas introduced into the mixing device in appropriate ranges. Can be increased.
In particular, the production method according to the present invention was able to immobilize the charge control agent in a uniform state at a relatively low temperature on the resin powder containing the release agent that becomes the toner base during the production of the toner for electrophotography. When a toner is used in a copying machine, a toner that has a stable chargeability, prevents filming contamination on a photoreceptor and a developing roller, and has an excellent effect on long-term copying without causing spent on a carrier. To provide.

  The present invention relates to a method of mixing a resin powder containing a release agent and a surface treatment agent, using a mixer having a spherical container shape, the relationship between the stirring speed of the mixer, the Tg of the resin and the mixing temperature, and the mixing container. By specifying the relationship between the temperature of the refrigerant for temperature control supplied to the jacket and the dew point of the gas to be forcibly replaced in the mixing tank, the resin is stirred and mixed at a relatively low temperature and contains a release agent and has a low glass transition temperature. In this method, the charge control agent is immobilized in a uniform state to efficiently produce the surface-treated resin powder.

With the low-temperature fixing in the electrophotographic image forming process in recent years, the melting point of the toner used has been lowered, and as a resin constituting the toner base particles, a resin having a glass transition temperature Tg of about 50 to 70 ° C. Usually, it is preferably used.
In order to efficiently fix the charge control agent to the resin powder without deteriorating the quality by stirring and mixing, it is desirable to perform the treatment in a temperature range of Tg-35 to Tg-10 ° C. based on Tg.
When T <Tg−35 ° C., there is a case where there is no heat generation due to collision between the stirring blade and the powder or between the powders, that is, a case where the fixing is not sufficiently performed. Conversely, when T> Tg−10 ° C., the calorific value exceeds the cooling capacity. For example, in the case of an electrophotographic toner, the release agent contained in the resin powder particles may be exposed on the particle surface.
Such a toner has a problem that storage stability is reduced and the inside of the image forming apparatus is stained. Further, since the low-melting-point substance melts out and forms toner aggregates by fusing, new classification and removal are required for use as an electrophotographic toner, which is not efficient.

The fluidized stirring type mixing apparatus used in the production method of the present invention has a spherical shape in a mixing vessel, and at least a rotating body is disposed at the bottom, and the rotating body is provided with a plurality of stirring blades.
By rotating the rotating body, the toner base particles and the surface treating agent particles such as a charge control agent (both particles are collectively referred to as powder) are stirred and mixed in the stirring tank, and the powder is placed on the rotating body. After flowing toward the tank wall, the air flows upward along the tank wall, then returns from the top of the tank wall to the center of the rotating body, collides with each other during the reflux, and as a result, the toner matrix The surface treatment agent particles adhere to the particle surfaces and are fixed, whereby a desired toner is manufactured.

As described above, the fluid stirring type mixing device used in the present invention preferably has no projecting portion as the inner wall of the device, and projects from the inner wall around the rotating body, or has a spherical shape having no irregularities on the inner wall. Are preferred.
In the case of a mixing device having an uneven wall surface, for example, a hybridizer described in JP-A-5-34971, the toner base particles collide with the mixing device wall surface due to high-speed rotation, generate friction, and generate heat. There is a possibility that the part is fused and aggregated, or the release agent is exposed, so that the physical properties of the toner are changed.
When there is a projecting portion on the inner wall surface of the device, the projecting height is preferably 1 mm or less, more preferably 0.5 mm or less.
When the powder flows at a high speed on the smooth inner wall, the surface of the powder can be uniformly treated without further pulverization of the toner base particles.
If the inner wall has projections and is not smooth, turbulence is likely to occur in the high-speed airflow, excessive pulverization of the particles, local melting of the particle surface, lack of uniformity in the processing of the powder (the energy applied between the particles Variation).

For example, a sensor for measuring the internal temperature, or a protrusion in the direction of the axis of the rotating body for preventing powder from adhering to the inner wall, as a part forming a protruding portion from the inner wall surface of the device in the present invention. Excluded members are not included.
A more preferable form of the stirring device is a device in which the device is a substantially spherical body having no cylindrical or flat inner wall and has a continuous curved surface.
Except for the continuous curved surface, a powder discharge device, a gas discharge port, and the like are not included. Such a continuous curved surface creates a stable and turbulent high-speed airflow, and creates uniformity of energy applied between particles including the resin powder to be treated. For example, a Q-type mixer (made by Mitsui Mining Co., Ltd.) is mentioned as a suitable example.

FIG. 2 is a schematic view of a device having a spherical wall, and arrows represent the trajectories of powder reflux in the device. This will be described in more detail with reference to FIG.
When two or more kinds of powders are mixed by a stirring blade using a device having a spherical wall, the behavior of the powder in the device firstly collides with the stirring blade at the bottom of the device, thereby causing a large centrifugal force. Receiving the water and then struck toward the inner wall surface of the device, and then reach the top along the inner wall surface by the high-speed airflow generated by the high-speed rotation of the stirring blade, and further ride on the high-speed airflow descending from the top toward the rotating shaft, thereby stirring the stirring blade. It is carried to the upper part, and it is launched again and the circulation is repeated.

  Therefore, in the present invention, the use of a spherical mixing vessel, which is the most preferable shape of the wall of the device for mixing and stirring and refluxing the powder, is used as the stirring device for generating such a powder trajectory. Circulation is always performed stably, and there is no stagnation at the bottom of the container, which is a drawback of the conventional vertical cylindrical mixer, and uniform processing is performed. As a device having a spherical mixing vessel, for example, a Q-type mixer (manufactured by Mitsui Mining Co., Ltd.) is mentioned as a suitable example.

When the powder is stirred and mixed at high speed, various forces including impact force are applied to the powder, and excess energy is released as heat energy, so that the temperature inside the device increases. If the internal temperature rises excessively, a part of the toner base particles will be melted, or the release agent will be exposed, adversely affecting the quality.
As a device having a spherical wall used in the present invention, in order to suppress such heat generation, as shown in FIG. 3, a device having a double structure having a jacket on the outside of the device and capable of flowing a cooling medium is used. Used.
The powder ejected by the stirring blade is once transported to the top along the wall surface by the high-speed airflow, and is thereby cooled. Further, the stirring blade rotating at high speed is also cooled by the flow of the refrigerant. Therefore, surface treatment can be performed efficiently while suppressing an increase in the internal temperature.

  When the stirring speed (peripheral speed) in the fluidized stirring type mixing device is set to 65 to 115 m / s, preferably 70 to 100 m / s, a large impact force is applied to each particle, and the particles are further ejected by the impact force. Since the particles have a large velocity, they can move at high speed in the apparatus, and the charge control agent is fixed to the toner matrix. If the stirring speed is less than 65 m / s, the impact force is insufficient, and it is difficult to reliably fix the charge control agent to the toner base. If it exceeds 115 m / s, the heat generated by the toner matrix increases, and it becomes difficult to maintain Tg-10 ° C.

In order to stir at an atmosphere temperature (T ° C.) in a mixing apparatus such that Tg-10>T> Tg-35 (Tg: glass transition temperature (° C.) of resin powder), high-speed stirring and mixing are performed. It is effective to suppress a rise in temperature due to heat generation due to heat.
The temperature rise can be suppressed by flowing a refrigerant having a temperature equal to or lower than the mixing device installation environment temperature to the jacket portion of the mixing device.
A more preferable refrigerant temperature is any temperature of -5 to 15 ° C. When the refrigerant temperature is lower than −5 ° C., although the cooling effect is large, dew condensation easily occurs inside the mixing container, and aggregation of the toner base particles occurs due to the dew condensation, making uniform mixing difficult. If the temperature of the refrigerant is higher than the environment temperature of the apparatus, the resin powder cannot be sufficiently cooled, and the processing temperature exceeds the range of Tg-10 ° C. Become. It is desirable that the temperature of the refrigerant in the case of performing the stirring and mixing process at the normal environment temperature of the apparatus installation is 15 ° C. or less. More preferably, it is -5C or less.

By flowing the cooling medium through the jacket of the stirring and mixing apparatus, the internal surface of the mixing apparatus is cooled to a temperature substantially equal to that of the cooling medium, and the excessive temperature increase of the toner base particles is prevented.At this time, the gas existing inside the mixing apparatus is also cooled. Depending on the conditions of temperature and humidity, condensation may occur inside the mixing tank. If the stirring and mixing process is performed in a state where dew condensation has occurred, the powder will aggregate.
In order to prevent this, it is effective to use a dry gas whose dew point temperature is lower than the refrigerant temperature flowing through the jacket and stir and mix while forcibly replacing the gas inside the mixing device. More preferably, it is effective to forcibly replace the gas with a gas that satisfies the relationship of dew point temperature at atmospheric pressure of the gas <jacket refrigerant temperature−5 ° C.

By using a gas that satisfies the relationship of dew point temperature of gas under atmospheric pressure <jacket refrigerant temperature−5 ° C., stable production can be performed without being affected by fluctuations in the stirring and mixing environment (temperature and humidity). Dry gas having a relation of dew point temperature of gas under atmospheric pressure <jacket refrigerant temperature−10 ° C. is more preferable.
From the relationship with the refrigerant temperature, the range of the dew point temperature of the dry gas under the atmospheric pressure is at least 13 ° C. or less, and preferably -10 ° C. or less.
As shown in FIG. 5, the dried gas is subjected to a drying process through a taken-in air through a compressor and a drier, adjusted to a predetermined dew point temperature, and used for replacement inside the mixing device.
The temperature of the air after the drying treatment is desirably adjusted to 15 ° C. or less so as not to affect the temperature inside the apparatus.

  As shown in FIG. 3, it is desirable that the dry gas used to forcibly replace the air inside the mixing apparatus is introduced from the rotary shaft seal of the stirring blade. By introducing the dry gas from the vicinity of the stirring blade, the gas is easily dispersed in the mixing vessel, and is introduced from the vicinity of the center of the vessel, so that uniform stirring and mixing is ensured without disturbing the gas flow in the vessel.

It is appropriate that the gas that has been forcibly displaced from the inside of the mixing device be discharged from the mixing device so that the gas and the powder can be easily separated, and that the gas does not disturb the reflux trajectory in the container.
As shown in FIG. 3, by discharging from the hollow interior pipe vertically penetrating from the upper part of the mixing device to the inside, the flow of the powder fluid in the container and the flow of the exhaust gas are in opposite directions, so that Separation of gas and powder becomes easier.
In addition, by being located at the center of the container, the flow of the powder fluid in the container can be prevented from being disturbed, and the gas can be effectively replaced and discharged.

  When the supply of dry gas is stopped for a long time, or when the mixing tank is emptied and the residual powder is removed, the refrigerant filled in the jacket and the stirring blade is replaced with a refrigerant at least at room temperature or higher to replace the inside of the mixing tank. Dew condensation can be prevented, and coagulation of residual powder and wetting of the inner wall of the mixing tank can be prevented. Cooling tower water or the like can be used as the refrigerant at room temperature or higher.

In order to immobilize the surface treatment agent on the base particles, it is important to increase the number of collisions between the blades and the particles or particles, and furthermore, to eject the particles toward the inner wall surface with a large centrifugal force. And give sufficient impact force to the powder.
The impact force received by the powder from the blade when colliding with the rotating blade is such that the component in the rotation direction is the largest, so that as much as possible the force of the rotation direction component can be transmitted to the powder as a shape of the stirring blade. For example, a plurality of blades having surfaces perpendicular to the rotation direction as shown in FIG. 4 are provided, and stirring blades arranged radially are preferable.

Since the powder flowing by the high-speed air flow in the shape container comes directly down from the top of the container onto the stirring blade, the impeller having a plane perpendicular to the rotation direction converts all impact forces into powder as a component in the rotation direction. You can pass on.
Therefore, if the impeller according to the present invention is used, the energy due to rotation can be utilized to the maximum.
The number of blades is determined by the probability of collision with the powder, that is, the number of rotations used and the capacity of the container, and preferably 4 to 12 when the device capacity is 20 to 150 liters.

In the fluidized stirring type mixing device used in the present invention, the powder is constantly circulating. However, if the charged amount is small, most of the toner base particles adhere to the device wall, and not only the stirring efficiency is not improved but also the yield is improved. Will decrease. Further, since the toner base particles that have been adhered are in an unprocessed state, there is a possibility that the unprocessed substance may be mixed into the resulting mixture.
When the charged amount is 0.2 times or more of the container capacity, the self-cleaning mechanism of the circulating toner base particles operates to scrape off the adhesion by the toner base particles themselves, so that the toner base particles which are not processed while being attached are eliminated. The toner is uniformly processed and can be manufactured.
If the charge amount is increased, the heat generated by the powder increases, the cooling effect from the tank wall does not reach uniformity, the temperature of the powder partially rises, and the low-melting substance melts out of the toner matrix, affecting the toner quality. Therefore, it is desirable that the charged amount be 0.6 times or less the container capacity.
In order to circulate the powder uniformly and to obtain the optimum stirring efficiency, the charged amount is preferably 0.2 to 0.6 times the container capacity, particularly 0.3 to 0.4 times. Is more preferred.

  As the toner base particles to be processed by the stirring type mixing device that generates the above-mentioned powder recirculation locus used in the present invention, those having a volume average particle diameter Dv of 3 to 7.5 μm are preferable. When Dv is less than 3 μm, the mass of the powder is too small, so that it is difficult to fix the amount of energy that can be provided by the stirring blade. On the other hand, if Dv is larger than 7.5 μm, the particles will be crushed, and not only will the Dv after treatment change, but also affect the quality.

In the fluidized stirring type mixing apparatus used in the present invention, the charge control agent used for the adhesion treatment on the surface of the toner base particles preferably has a primary particle diameter of 5 to 300 nm.
If the primary particle diameter is smaller than 5 nm, the mass is too small and the particles float in the stirrer, and the adhesion treatment tends to be difficult. On the other hand, if the primary particle diameter is larger than 300 nm, the adhesion cross-sectional area with respect to the surface area of the toner base particles is too large.

Known charge control agents can be used.
For example, nigrosine dye, triphenylmethane dye, chromium-containing metal complex dye, molybdate chelate pigment, rhodamine dye, alkoxy amine, quaternary ammonium salt (including fluorine-modified quaternary ammonium salt), alkylamide, phosphorus Or a compound of tungsten, a simple substance or compound of tungsten, a fluorine-based activator, a metal salt of salicylic acid, and a metal salt of a salicylic acid derivative.
Specifically, bontron 03 of a nigrosine dye, bontron P-51 of a quaternary ammonium salt, bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, and E of a salicylic acid metal complex -84, phenolic condensate E-89 (all manufactured by Orient Chemical Industry Co., Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (all manufactured by Hodogaya Chemical Industry Co., Ltd.), quaternary Copy charge PSY VP2038 of ammonium salt, copy blue PR of triphenylmethane derivative, copy charge NEG VP2036 of quaternary ammonium salt, copy charge NX VP434 (all from Hoechst), LRA-901, LR- which is a boron complex 147 (manufactured by Nippon Carlit Co., Ltd.), copper phthalocyanine, perylene, quinacrid , Azo pigments, sulfonate group, a carboxyl group, such as polymer compounds having a functional group such as quaternary ammonium salts.

  In order to use a resin powder having an improved chargeability by fixing a charge control agent as an electrophotographic toner, it is necessary to mix and adhere a flow aid to improve the flowability. In order to mix and adhere the flow aid, it is preferable to use a commonly used vertical cylindrical stirrer such as a Henschel mixer or the above-described spherical mixer to mix and adhere at a peripheral speed of 30 to 40 m / s.

  Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto. Hereinafter, "part" indicates "part by weight". 2 and 3 are used as the fluid stirring type mixing apparatus and the impeller as a rotating body.

(Example 1)
In a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe, 810 parts of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenol) propane, 300 parts of terephthalic acid and dibutyltin oxide 2 were added. After reacting at 230 ° C. for 8 hours at normal pressure and further reacting for 5 hours at a reduced pressure of 10 to 15 mmHg, the mixture was cooled to 160 ° C., and 32 parts of phthalic anhydride was added thereto and reacted for 2 hours. .
Next, the mixture was cooled to 80 ° C. and reacted with 188 parts of isophorone diisocyanate in ethyl acetate for 2 hours to obtain an isocyanate-containing prepolymer (1). Next, 267 parts of the prepolymer (1) and 14 parts of isophoronediamine were reacted at 50 ° C. for 2 hours to obtain a urea-modified polyester (1) having a weight average molecular weight of 58,000.
Similarly to the above, 724 parts of bisphenol A ethylene oxide 2 mol adduct and 276 parts of terephthalic acid are polycondensed under normal pressure at 250 ° C. for 5 hours, and then reacted under reduced pressure of 10 to 15 mmHg for 5 hours to obtain a peak molecular weight of 5,000. An unmodified polyester (a) was obtained.
150 parts of the urea-modified polyester (1) and 850 parts of the unmodified polyester (a) were dissolved and mixed in 2,000 parts of an ethyl acetate solvent to obtain an ethyl acetate solution of the toner binder (1).

To 240 parts of the above ethyl acetate solution of the toner binder (1), 4 parts of carbon black (Regal 400R, manufactured by Cabot Corporation) as a coloring agent and 5 parts of carnauba wax (melting point: 83 ° C.) as a releasing agent wax were added. Was stirred at 12,000 rpm with a TK homomixer to uniformly dissolve and disperse.
Next, 706 parts of ion-exchanged water, 294 parts of a hydroxyapatite 10% suspension (Supatite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 part of sodium dodecylbenzenesulfonate were added and uniformly dissolved. Then, the temperature was raised to 50 ° C., and the above-mentioned toner material solution was charged and stirred for 10 minutes while stirring at 12,000 rpm with a TK homomixer.
Thereafter, the mixed solution was transferred to a kolben equipped with a stir bar and a thermometer, heated to 98 ° C. to remove the solvent, separated by filtration, washed and dried, and had a volume average particle size of 5.5 μm and a glass transition temperature of 5.5 μm. Was 50 ° C. to obtain toner base particles.

100 parts of toner base particles having a Tg of 50 ° C. and a volume average particle size of 5.5 μm containing a binder resin, a colorant, and a release agent produced by the polymerization method as described above, and a primary particle size of 50 nm Of a charge control agent (salicylic acid metal complex E-84: Orient Chemical Industries) is a Q-type mixer (Mitsui Mining Co., Ltd.) having a capacity of 20 liters, which is a fluid stirring type mixing apparatus having a spherical mixing vessel shape. ), The peripheral speed of the impeller was set to 65 m / s, and a 15 ° C refrigerant was supplied to the jacket, and dry air at a dew point of -10 ° C was supplied at 3 L / min. While the maximum temperature in the apparatus was set to 35 ° C., a mixing process was performed for 15 minutes. The room temperature, which was the environment during the treatment, was 25 ° C.
Since the maximum temperature in the apparatus reached 35 ° C. in about 3 minutes by the mixing process, cooling was performed 4 times for 2 minutes on the way, and mixing was repeated 5 times, so that 23 minutes were required for the process.

(Comparative Example 1)
The same processing as in Example 1 was performed, except that the Q-type mixer in Example 1 was a vertical cylindrical cylindrical Henschel mixer (manufactured by Mitsui Miike Kakoki Co., Ltd.) having a capacity of 20 liters.
Since the maximum temperature in the container reached 35 ° C. in about 1 minute by the mixing process, the mixing was repeated 15 times, taking 14 cooling times for 2 minutes, and 43 minutes was required for the process.

(Example 2)
The same processing as in Example 1 was performed except that the peripheral speed of the impeller in Example 1 was set to 70 m / s.
Since the maximum temperature in the container reached 35 ° C. in about 3 minutes by the mixing process, the mixing was repeated 5 times with 2 minutes on the way and 4 cooling times, so that 23 minutes was required for the process.

(Example 3)
The same processing as in Example 2 was performed except that water at 8 ° C. was passed through the jacket in Example 2.
Since the maximum temperature in the container reached 35 ° C. in about 6 minutes due to the mixing treatment, mixing was repeated three times with two cooling times for one minute, so that 17 minutes were required for the treatment.

(Comparative Example 2)
The same processing as in Example 3 was performed, except that the maximum temperature in the container in Example 3 was set to 45 ° C., and the processing was performed under the relationship of Tg−5 ° C. Since the maximum temperature was 44 ° C. and the operation could be performed continuously for 15 minutes, the processing time was 15 minutes.

(Comparative Example 3)
The same processing as in Example 3 was performed, except that the drying was performed while supplying undried air having a dew point of 16 ° C. at a rate of 3 liters / minute in place of the dry air having a dew point of −10 ° C. in Example 3.
Since the maximum temperature in the vessel reached 35 ° C. in about 6 minutes by the mixing treatment, the mixing was repeated three times with two cooling times for one minute, so that 17 minutes were required for the treatment.

(Example 4)
The same processing as in Example 3 was performed except that the maximum temperature in the container was set to 20 ° C through the refrigerant (brine) of -5 ° C in the jacket in Example 1.
Since the maximum temperature in the vessel reached 20 ° C. in about 5 minutes by the mixing treatment, the mixing was repeated three times with two cooling times for one minute on the way, so the treatment required 17 minutes.

(Comparative Example 4)
The same processing as in Example 4 was performed, except that the maximum temperature in the container in Example 4 was set to 20 ° C.
Since the maximum temperature in the container reached 20 ° C. in about 2 minutes by the mixing process, mixing was repeated eight times with seven cooling times for 1.5 minutes on the way, so that the processing required 25 minutes.

(Example 5)
The same processing as in Example 3 was performed except that the peripheral speed of the impeller in Example 3 was set to 90 m / s.
Since the maximum temperature in the container reached 35 ° C. in about 5 minutes by the mixing treatment, the mixing was repeated three times with two cooling times for one minute, so that 17 minutes were required for the treatment.

(Comparative Example 5)
The same processing as in Example 5 was performed except that the peripheral speed of the impeller in Example 5 was set to 50 m / s.
Since the maximum temperature in the container reached 35 ° C. in about 12 minutes by the mixing process, the mixing was repeated twice with one cooling time taking one minute on the way, so that 16 minutes was required for the processing.

(Comparative Example 6)
The same processing as in Example 5 was performed except that the peripheral speed of the impeller in Example 5 was 125 m / s.
Since the maximum temperature in the container reached 35 ° C. in about 2.5 minutes by the mixing process, mixing was repeated 6 times with 5 minutes cooling time for 1 minute on the way, so that 20 minutes was required for the process.

(Example 6)
The same processing as in Example 3 was performed except that the peripheral speed of the impeller in Example 3 was set to 115 m / s.
Since the maximum temperature in the vessel reached 35 ° C. in about 3 minutes by the mixing process, the mixing was repeated 5 times with 4 minutes cooling time for 1 minute on the way, so 19 minutes was required for the process.

Evaluation of productivity In order to perform mixing for substantially 15 minutes at Tg-10>T> Tg-35 (T: processing temperature (° C.), Tg: glass transition temperature (° C.) of resin powder), cooling time is required during the process. , And the total processing time differs depending on the embodiment and the comparative example.
The total processing time was used as a productivity evaluation index, and the results are shown in Table 1.

In order to compare the mixing states, the degree of aggregation of the toner obtained in each of the examples and comparative examples was determined as follows.
The degree of aggregation serves as an index of how much the charge control agent is fixed to the toner base. If the aggregation degree of the toner base and the charge controlling agent after stirring and mixing is 20 to 70%, preferably 25 to 60%, and more preferably 30 to 50%, the chargeability is high.
Sieves having openings of 75, 45, and 22 μm are sequentially stacked, and 2 g of the sample is naturally dropped by vibration.
a = (weight of sample remaining on upper sieve) / 2 g × 100
b = (weight of sample remaining on middle sieve) / 2 g × (3/5) × 100
c = (weight of sample remaining on lower sieve) / 2 g × (１ ／) × 100
Cohesion degree = a + b + c (%)
：: cohesion degree is 30 to 50
Δ: Aggregation degree of 20 to 70 and other than 30 to 50 ×: Aggregation degree of other than 20 to 70 Further, in order to examine the degree of indentation, the state of the charge control agent on the toner surface was observed by SEM.
：: Completely immobilized Δ: Partially immobilized ×: Free These results are shown in Table 2.

  To 100 parts of each toner obtained above, 0.1 part of hydrophobic silica was mixed with a Henschel mixer. A developer composed of 4% by weight of each of these toners and 96% by weight of a copper-zinc ferrite carrier coated with a silicone resin and having an average particle diameter of 50 μm is prepared, and can be used to print 45 sheets of A4 size paper per minute. Printing was performed using the sample No. 450, and those having acceptable starting quality were continuously printed and evaluated according to the following criteria.

(Evaluation item)
(A) Charge amount (charge control agent adhesion amount index)
6 g of the developer is weighed, charged into a sealable metal cylinder and blown to determine the charge amount. The toner concentration is adjusted to 4.5 to 5.5 wt%.
(B) Background dirt (uniform charging index)
The blank image was stopped during the development, the developer on the photoreceptor after the development was transferred to a tape, and the difference from the image density of the untransferred tape was measured with a 938 spectrodensitometer (manufactured by X-Rite).
(C) Spent ratio (bleed index from toner)
The toner is removed by blow-off from the developer after the 10,000-sheet copy test, and the weight of the remaining carrier is measured W1. Next, this carrier is put in toluene to dissolve the melt, washed, dried and weighed to obtain W2. Then, the ratio of spent was determined by the following equation and evaluated.
Spent ratio = [(W1−W2) / W1] × 100
：: 0 to 0.01 wt%
：: 0.01 wt% to 0.02 wt%
Δ: 0.02% to 0.05% by weight
×: 0.05 wt% <
(D) Filming (surface fixation index)
The occurrence of toner filming on the developing roller or the photosensitive member was observed.が indicates no filming, Δ indicates filming on streaks, and × indicates filming as a whole.

The following is clear from Tables 1, 2, and 3.
(1) From Example 1 and Comparative Example 1, the spherical mixer of the present invention has much higher productivity, fixing quality and toner quality than the Henschel mixer which is a cylindrical fluidized stirring mixer.
(2) From Examples 1, 2, 5, and 6 and Comparative Examples 5 and 6, by making the peripheral speed appropriate, the state of fixing is excellent and the toner quality is good. If the peripheral speed is low, immobilization is insufficient and the charge level is low. If the peripheral speed is too high, the spent and filming quality is inferior.
(3) From Example 3 and Comparative Example 3, the toner quality is improved by properly maintaining the difference between the refrigerant temperature and the dew point temperature of the gas supplied to the mixing tank. If the dew point temperature is higher than the refrigerant temperature, the quality is greatly deteriorated.
(4) The productivity is improved by lowering the temperature of the refrigerant to the jacket than in Examples 2 and 3. (5) Tg−10> T from Examples 3, 4 and 5 and Comparative Examples 2 and 4. If the mixing is performed within a temperature range of> Tg-35 (Tg: glass transition temperature of resin powder (° C.)), the fixed state and the toner quality are good. When a gas having an appropriate dew point is supplied to the mixing tank, the toner quality is good.

It is the schematic which shows the conventional vertical cylindrical mixer. It is the schematic which shows an example of the stirring tank of the stirring apparatus used for this invention. It is the schematic which shows the example of the stirring apparatus provided with the jacket for temperature control used for this invention. It is the schematic which shows the shape of the blade of the rotating body which comprises the stirring tank of the stirring apparatus used for this invention. 1 is a schematic diagram illustrating an example of a system for adjusting a dry gas used in the present invention.

Claims (11)

A rotating stirrer having at least a rotating body having a stirring blade and a jacket for flowing a refrigerant through a wall to control the temperature is used, and a mixing vessel having a spherical shape is used as a fluid stirring type mixing device. By rotating at a stirring speed (peripheral speed), the toner base powder including at least the binder resin, the colorant and the release agent is mixed with the charge control agent with stirring, and the charge control agent is applied to the surface of the toner base powder. Is a method for producing an electrophotographic toner, wherein a refrigerant having a temperature equal to or lower than the installation environment temperature of the mixing device is flowed into the jacket and the stirring blade, and a dew point temperature in the mixing device is lower than the refrigerant temperature. While the air in the mixing apparatus is being forcibly replaced, and the atmosphere in the apparatus is such that Tg-10> T> Tg-35 (Tg: glass transition temperature (° C.) of the resin powder). temperature Electrophotographic method for producing a toner, which comprises stirring at T ° C.). 2. The toner for electrophotography according to claim 1, wherein the stirring blade in the fluidized stirring type mixing device stirs at a stirring speed (peripheral speed) of 70 to 100 m / s to fix the charge control agent. Manufacturing method. The electrophotographic toner according to claim 1, wherein the cooling refrigerant of the mixing device is maintained at an arbitrary constant temperature of −5 to 15 ° C., and the toner base powder and the charge control agent are stirred. Production method. 4. The electronic device according to claim 1, wherein a dry gas used for forcibly replacing air in the mixing device is introduced from a rotation shaft of the stirring blade and a rotation shaft seal of the mixing tank. 5. A method for producing a photographic toner. The toner for electrophotography according to any one of claims 1 to 4, wherein the gas that has been forcibly replaced from the inside of the mixing device is discharged from a hollow interior tube vertically penetrating from the upper portion of the mixing device to the inside. Manufacturing method. 6. The electrophotographic toner according to claim 1, wherein a dry gas having a relation of dew point of gas <jacket refrigerant temperature−5 ° C. is used to replace the air inside the mixing device. Manufacturing method. The method for producing an electrophotographic toner according to any one of claims 1 to 6, wherein a coolant at room temperature or higher can flow through the jacket of the mixing device. The method according to any one of claims 1 to 7, wherein the stirring blade is an impeller located radially. 9. The method for producing an electrophotographic toner according to claim 1, wherein the stirring and mixing amount of the toner base powder is 0.2 to 0.6 times the container amount used for mixing. The method for producing an electrophotographic toner according to claim 1, wherein the toner base powder has an average particle diameter of 3 to 7.5 μm. The method for producing an electrophotographic toner according to any one of claims 1 to 10, wherein a primary particle diameter of the charge control agent is 5 nm to 300 nm.

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