JPH11202553A - Production of polymerized toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a polymerized toner having a low fixing temp. and uniform meltability, excellent in preservability (blocking resistance) and fluidity, hardly causing fog and hardly lowering printing density. SOLUTION: A polymerizable monomer compsn. contg. at least a colorant, a polymerizable monomer and a releasing agent is suspended in an aq. dispersive medium contg. a dispersion stabilizer to form droplets. The compsn. is suspension-polymerized in the presence of an oil-soluble polymn. initiator until the rate of polymn. conversion attains to the range of 30-95%. While the rate of polymn. conversion is within the range, a reducer for the redox initiator is added to the dispersive medium, the suspension polymn. is further succeeded to form colored polymer particles and the objective polymerized toner is produced. When a polymerizable monomer for shells is suspension-polymerized in the presence of the colored polymer particles to form polymer layers as shells on the surfaces of the particles, the objective toner having a core/shell structure is produced.

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 polymerized toner, and more particularly, to a method for producing a polymerized toner suitable as a toner for developing an electrostatic image formed by an electrophotographic method, an electrostatic recording method or the like. .

[0002]

2. Description of the Related Art In an electrophotographic method or an electrostatic recording method, as a developer for visualizing an electrostatic image (electrostatic latent image), a two-component developer composed of toner and carrier particles, and substantially only a toner are used. And a one-component developer that does not use carrier particles. The one-component developer includes a magnetic one-component developer containing magnetic powder and a non-magnetic one-component developer containing no magnetic powder. In non-magnetic one-component developers, a fluidizing agent such as colloidal silica is often independently added (externally added) in order to enhance the fluidity of the toner. Generally, as the toner, colored particles obtained by dispersing a colorant such as carbon black, a charge control agent, and other additives in a binder resin and granulating them are used.

[0003] The methods for producing toner are roughly classified into a pulverization method and a polymerization method. In the pulverization method, a toner is obtained by melt-mixing a synthetic resin, a colorant, and other additives as necessary, pulverizing, and then classifying so as to obtain particles having a desired particle size. In the polymerization method, a polymerizable monomer composition is prepared by uniformly dissolving or dispersing various additives such as a colorant, a polymerization initiator, and, if necessary, a crosslinking agent and a charge controlling agent in the polymerizable monomer. And then dispersed in an aqueous dispersion medium containing a dispersion stabilizer using a stirrer to form fine droplet particles of the polymerizable monomer composition. As a result, a toner (polymerized toner) having a desired particle size is obtained.

[0004] Each developer substantially develops an electrostatic latent image with toner. Generally, in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, an image is formed on a uniformly charged photoconductor to form an electrostatic latent image, and toner is attached to the electrostatic latent image. To form a toner image (visible image), transfer the toner image onto a transfer material such as transfer paper, and then transfer the unfixed toner image onto the transfer material by various methods such as heating, pressing, and solvent vapor. Has established. In the fixing step, in many cases, a transfer material on which a toner image has been transferred is passed between a heating roll (fixing roll) and a pressure roll, and the toner is heated and pressed to be fused on the transfer material.

[0005] An image formed by an image forming apparatus such as an electrophotographic copying machine is required to have higher definition year by year. Conventionally, as a toner used in an image forming apparatus, a toner obtained by a pulverizing method has been mainly used. According to the pulverization method, colored particles having a wide particle size distribution are easily formed. Therefore, in order to obtain satisfactory development characteristics, it is necessary to classify the pulverized product and adjust the particle size distribution to a certain degree. However, the classification itself is complicated, the yield is poor, and the toner yield is greatly reduced. In the pulverization method, it is difficult to uniformly disperse additives such as a colorant and a charge control agent in the binder resin. When the dispersion state of these additives is poor, the fluidity, triboelectricity, durability, and development characteristics of the toner are adversely affected, and further, fog is increased and image density is reduced.

Therefore, in recent years, polymerized toners that can be easily controlled in particle size and do not need to go through complicated manufacturing steps such as classification have been attracting attention. According to the suspension polymerization method, a polymerized toner having a desired particle size and particle size distribution can be obtained at a high yield without performing pulverization or classification. In the suspension polymerization method, additives such as a coloring agent and a charge controlling agent are added to a polymerizable monomer which is a low-viscosity liquid and dispersed, so that a pulverization method in which these additives are dispersed in a resin is used. In comparison, the dispersibility becomes better. In addition, according to the suspension polymerization method, it is possible to obtain colored polymer particles having a sharp particle size distribution and good electric characteristics, so that it is possible to economically produce a polymerized toner having excellent image characteristics. is there. However, the conventional polymerized toner has a problem that it cannot sufficiently cope with recent demands for high-speed copying, full-color copying, and energy saving.

In recent years, in electrophotographic copying machines, printers, and the like, there has been a demand for a reduction in power consumption and an increase in the speed of copying and printing. In the electrophotographic method, a step of particularly consuming energy is a fixing step after transferring the toner from the photosensitive member onto a transfer material such as transfer paper. In the fixing step, a heating roll heated to a temperature of 150 ° C. or higher is usually used to heat and fuse the toner to fix it on the transfer material, and electric power is used as an energy source. It is required to lower the heating roll temperature from the viewpoint of energy saving. To lower the temperature of the heating roll, it is necessary to fix the toner at a lower temperature than before. That is, it is necessary to lower the fixing temperature of the toner itself. If a toner that can be fixed at a lower temperature than before can be used, the temperature of the heating roll can be lowered, but if the temperature of the heating roll is not so lowered, the fixing time can be shortened. Can also respond.

In designing a toner, in order to meet demands from an image forming apparatus such as energy saving and high-speed copying, it is only necessary to lower the glass transition temperature of a binder resin constituting the toner. However, when the toner is composed of a binder resin having a low glass transition temperature, during storage or transportation, or in a toner box of an image forming apparatus, the toners cause blocking, and are likely to be aggregated,
This results in a toner having poor storage stability.

[0009] On the other hand, it is required that color copying and color printing can be clearly performed by the electrophotographic method. For example, in full-color copying, it is not sufficient to simply melt and soften the toner and fuse it onto a transfer material in the fixing process, and it is necessary to uniformly melt-mix and mix the toners of each color. . That is, in the case of full-color copying, development is usually performed with three or four color toners, transferred onto a transfer material uniformly or divided three or four times, and then fixed. Therefore, it is required that the layer thickness of the toner to be fixed becomes thicker than that of a single-color image, and that color toners of a plurality of overlapping hues are uniformly melted and mixed. For this purpose, it is necessary to design the melt viscosity of the toner near the fixing temperature to be lower than that of the conventional toner. As a method for lowering the melt viscosity of the toner, there are methods such as lowering the molecular weight of the binder resin and lowering the glass transition temperature as compared with the conventional binder resin for toner.
However, in either case, the toner is liable to cause blocking, resulting in poor storage stability.

Conventionally, as a method for obtaining a polymerized toner having excellent fixing properties, for example, JP-A-3-13665 discloses a method in which a polymerizable monomer containing a colorant and a charge control agent is mixed with a macromonomer in the presence of a macromonomer. A method of suspension polymerization has been proposed. A macromonomer is a relatively long linear molecule having a polymerizable functional group at an end of a molecular chain, for example, an unsaturated group such as a carbon-carbon double bond. According to this method, since the macromonomer is incorporated as a monomer unit into the molecular chain of the produced polymer, a large number of branches resulting from long linear molecules of the macromonomer occur in the molecular chain. The resulting polymer is entangled by its branches, so-called physical crosslinking,
Since the polymer has a high molecular weight, the offset resistance of the polymerized toner is improved. On the other hand, the physical cross-linking by the macromonomer component has a loose cross-linking structure unlike the chemical cross-linking using a cross-linking monomer such as divinylbenzene, so that the cross-linking structure is easily broken by heating. Therefore, this polymerized toner is easily fused at the time of fixing using a heating roll, and thus has excellent fixability. However, this polymerized toner tends to cause aggregation between the toners during storage, and the storage stability was not satisfactory.

As described above, according to the conventional methods for lowering the fixing temperature of the toner and improving the uniform melting property, the fixing property of the obtained toner is improved, but the storability is reduced. Will happen. As a method for solving this inverse correlation, a toner composed of a binder resin having a low glass transition temperature is coated with a polymer having a high glass transition temperature to improve the blocking resistance, thereby solving the problem of storage stability. A so-called capsule type toner has been proposed. A method of encapsulating a wax in a polymerized toner has also been proposed as being effective in achieving both blocking resistance and low-temperature fixability.

As a method for producing a capsule type toner, for example, JP-A-60-173552 discloses a method in which a coloring agent or magnetic particles or A method of forming a coating layer composed of a conductive agent and a binder resin has been proposed. As the core particles, a thermoplastic transparent resin such as an acrylate resin or a styrene resin is used. This publication reports that this method provides a multi-layer toner having excellent fluidity and improved functionality. However, in this method, when core particles having a low glass transition temperature are used, the core particles themselves tend to aggregate. Further, in this method, the thickness of the binder resin to be attached to the core particles tends to be large. Therefore, in this method, it is difficult to obtain a toner having improved fixability and uniform melting property while maintaining storability.

In Japanese Patent Application Laid-Open No. 2-259657, crosslinked toner particles prepared by suspension polymerization are added to a solution in which an encapsulating polymer, a charge controlling agent and a release agent are dissolved in an organic solvent. Thereafter, a method for producing an electrophotographic toner has been proposed in which a poor solvent is added to form a coating of an encapsulating polymer containing a charge control agent and a release agent on the surface of crosslinked toner particles. However, in this method, since the solubility of the encapsulating polymer is reduced by dropping the poor solvent and is precipitated on the surface of the crosslinked toner particles, it is difficult to obtain true spherical particles. In this method, the capsule wall formed on the surface of the crosslinked toner particles is not uniform in thickness and is relatively thick. As a result, the effect of improving the developing property and the fixing property is not sufficient.

JP-A-57-45558 discloses that core particles formed by polymerization are mixed and dispersed in an aqueous solution of 1 to 40% by weight of latex, and then a water-soluble inorganic salt is added to the surface of the core particles. In addition, there has been proposed a method for producing a toner for developing an electrostatic charge image, in which a coating layer is formed by fine particles obtained by emulsion polymerization. However, this method has a drawback that the charging characteristics of the toner are largely dependent on the environment due to the effect of the surfactant and the inorganic salt remaining on the fine particles, and the charging is reduced particularly under high temperature and high humidity conditions. .

JP-A-61-118758 discloses that a composition containing a vinyl monomer, a polymerization initiator and a colorant is subjected to suspension polymerization to obtain core particles. Having a hydrophilicity equal to or higher than the resin contained in the core particles, and
There is disclosed a method for producing a toner in which a vinyl-based monomer giving a polymer having a glass transition temperature higher than the glass transition temperature of the resin is polymerized to form a shell, thereby forming a shell. The publication discloses that, in order to prevent a part of the melted toner from adhering to the surface of the fixing roll, a low molecular weight polyethylene,
It is disclosed that a release agent such as carnauba wax or silicone oil may be added. However, in this method, the vinyl-based monomer for forming a shell in the core particle is adsorbed and grown, so that the vinyl-based monomer absorbed into the core particle is polymerized, and the core particle becomes clear. It is often difficult to produce a core-shell structure. Therefore, with this method, it is difficult to obtain a toner with sufficiently improved storability. Furthermore, in this method, the thickness of the shell had to be increased in order to clarify the core-shell type structure and improve the storage stability.

JP-A-59-62870 discloses that a polymer particle formed by suspension polymerization of a toner material containing a monomer, a colorant and a polymerization initiator has a glass transition temperature of the polymer particle. There has been proposed a method for producing a toner using a polymerization method in which a monomer system capable of forming a polymer having a higher glass transition temperature is adsorbed and grown. However, this method has a drawback that when a wax as a release agent is contained in the polymer particles, the wax bleeds, so that even if it is encapsulated, the storage stability is deteriorated, and the fixing temperature is sufficiently lowered. Can not do. JP-A-57-
Japanese Patent No. 41648 proposes a macrocapsule toner having a core material and an outer shell covering the core material, wherein the core material contains a wax having 26 to 50 carbon atoms. However, this method has a drawback that the low melting point wax bleeds on the surface of the core material, and the shelf life is deteriorated even when the outer shell is formed.

Japanese Patent Application Laid-Open No. 7-128908 discloses a polymerized toner which can be obtained directly by subjecting a monomer composition containing a polymerizable monomer, a colorant and a release agent to suspension polymerization in an aqueous medium. Wherein the release agent is contained in an amount of 10 to 40 parts by weight based on 100 parts by weight of the polymerizable monomer, and the step of removing the release agent from the toner surface after the polymerization step is completed. It has been disclosed. In this method, a developing sleeve, a photosensitive drum,
It is possible to reduce contamination due to adhesion of a release agent (wax) to a transfer drum or the like. However, according to this method, it is not possible to sufficiently improve the storability, the fixing temperature, and the like of the toner, and it is easy to cause fogging and decrease in print density.
As described above, it is said that the toner obtained by the polymerization method can achieve both the contradictory performances of blocking resistance and low-temperature fixability by encapsulating a low melting point wax. The wax precipitates or bleeds, and there is a limit to the compatibility of these properties.

[0018]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low fixing temperature and a uniform melting property, excellent storage stability (blocking resistance) and fluidity, furthermore, generation of fog and reduction in print density. It is an object of the present invention to provide a method for producing a polymerized toner which is unlikely to cause such problems. Another object of the present invention is to provide a method for producing a polymerized toner capable of coping with high-speed copying and printing, full color printing, and energy saving.
The present inventors have conducted intensive studies to overcome the problems of the prior art, and found that a polymerizable monomer composition containing a colorant, a polymerizable monomer, and a release agent was subjected to suspension polymerization. In the method for producing a polymerized toner, first, suspension polymerization is performed in the presence of an oil-soluble polymerization initiator (first-stage polymerization step),
By adding a reducing agent for redox initiator to the reaction system and continuing the polymerization reaction (later polymerization step), the preservability (blocking resistance) is improved without impairing the fluidity and the fixing temperature is lowered. It has been further found that a polymerized toner having a small image quality dependence on the environment and excellent in durability can be obtained.

By coating this polymerized toner with a polymer layer (shell) having a high glass transition temperature and encapsulating it, these properties can be further improved.
Further, in the production method of the present invention, various properties can be improved by using a macromonomer together with the polymerizable monomer. Further, when a polyfunctional ester compound such as pentaerythritol tetramyristate is used as a release agent, these properties can be further improved. Combinations of these methods are also effective. The present invention has been completed based on these findings.

[0020]

According to the present invention, the following inventions are provided. 1. (1) a step of suspending a polymerizable monomer composition containing at least a colorant, a polymerizable monomer, and a release agent in an aqueous dispersion medium containing a dispersion stabilizer to form droplets;
(2) a step of subjecting the polymerizable monomer composition to suspension polymerization in the presence of an oil-soluble polymerization initiator until the polymerization conversion is in the range of 30 to 97%; and (3) the polymerization conversion is as described above. A method for producing a polymerized toner, comprising a step of adding a reducing agent for a redox initiator to an aqueous dispersion medium when the amount is within the range, and further continuing suspension polymerization to generate colored polymer particles.

2. (1) a step of suspending a polymerizable monomer composition containing at least a colorant, a polymerizable monomer, and a release agent in an aqueous dispersion medium containing a dispersion stabilizer to form droplets; (2) a step of subjecting the polymerizable monomer composition to suspension polymerization in the presence of an oil-soluble polymerization initiator until the polymerization conversion is in the range of 30 to 97%, and (3) the polymerization conversion is in the above range. A step of adding a reducing agent for a redox initiator to the aqueous dispersion medium to further continue the suspension polymerization to form colored polymer particles (a), and (4) the colored polymer In the presence of the particles (a), a polymerizable monomer for shell capable of forming a polymer having a glass transition temperature higher than the glass transition temperature of the polymer component constituting the colored polymer particles (a) is suspended. A polymer which is subjected to turbid polymerization to form the colored polymer particles (a) as core particles and to form a shell on the surface thereof Method for producing a polymerized toner of a core-shell structure comprising a step of producing the formed colored polymer particles (b) a.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION (Production Method of Polymerized Toner) The polymerized toner of the present invention is produced by a suspension polymerization method. In general, in the suspension polymerization method, a polymerizable monomer composition containing at least a polymerizable monomer and a colorant is added to an aqueous dispersion medium containing a dispersion stabilizer, suspended, and then polymerized. By performing suspension polymerization in the presence of an initiator, colored polymer particles (polymerized toner) are generated. In the first invention of the present application,
(1) a step of suspending a polymerizable monomer composition containing at least a colorant, a polymerizable monomer, and a release agent in an aqueous dispersion medium containing a dispersion stabilizer to form droplets; (2) a step of subjecting the polymerizable monomer composition to suspension polymerization in the presence of an oil-soluble polymerization initiator until the polymerization conversion is in the range of 30 to 97%; and (3) the polymerization conversion is as described above. When the content is within the range, a reducing agent for a redox initiator is added to the aqueous dispersion medium, and the suspension polymerization is further continued to produce a polymerized toner by a process of generating colored polymer particles.

In the second invention of the present application, in the presence of the colored polymer particles (a) obtained in the first invention, a glass having a glass transition temperature higher than the glass transition temperature of the polymer component constituting the colored polymer particles (a) is used. The polymerizable monomer for shell capable of forming a polymer having a transition temperature is subjected to suspension polymerization to obtain the colored polymer particles (a).
Is used as a core particle, and a step of generating a colored polymer particle (b) in which a polymer layer serving as a shell is formed on the surface thereof,
A core-shell type polymerized toner (capsule type polymerized toner) is manufactured.

First, the first invention of the present application will be described in detail.
The polymerizable monomer composition used in the present invention contains a colorant, a polymerizable monomer, and a release agent as essential components. As the polymerizable monomer, a vinyl monomer is usually used. As the polymerizable component, it is preferable that a crosslinkable monomer or a macromonomer is further contained.
In addition to the colorant and the release agent, if necessary, for example, additives such as a charge control agent, a lubricant, and a dispersing agent, and a molecular weight modifier can be added. In addition, the polymerizable monomer composition,
Although an oil-soluble polymerization initiator may be contained from the preparation stage, in order to prevent early gelation, after suspending the polymerizable monomer composition in an aqueous dispersion medium to form droplets, It is preferable to add an oil-soluble polymerization initiator to the aqueous dispersion medium.

The polymerizable monomer composition is prepared by mixing the components with a mixing and dispersing machine such as a bead mill. An aqueous dispersion medium containing a dispersion stabilizer is prepared in advance, and the polymerizable monomer composition is charged therein and stirred to form droplets. At this stage, it is preferable to stir until the particle diameter of the droplet is stable and uniform. Thereto, an oil-soluble polymerization initiator is added, and the droplets are further refined. After polymerization, fine droplets are granulated so as to obtain a polymerized toner having a desired particle size. In this granulation step, the oil-soluble polymerization initiator is:
It is absorbed in the droplets of the polymerizable monomer composition. In order to miniaturize the droplets of the polymerizable monomer composition, they are usually dispersed using a mixing device having a high shearing force. As a preferred granulation method, for example, in the gap between the rotor rotating at high speed and the stator surrounding it and having a small hole or comb teeth,
There is a method in which the suspension is circulated and granulated.

The dispersion state of the polymerizable monomer composition in the aqueous dispersion medium is such that the volume average particle diameter of the droplets is usually 0.1 to 10%.
The state is 20 μm, preferably 0.5 to 10 μm. If the droplets are too large, the particle size of the resulting polymerized toner will be too large and the resolution of the image will be reduced. The volume average particle diameter / number average particle diameter of the droplets of the polymerizable monomer composition is usually 1.0 to 3.0, preferably 1.0 to 2.0. If the particle size distribution of the droplets is too wide, the fixing temperature varies, causing problems such as fogging and filming (for example, a phenomenon of forming a toner film on a photoconductor). The droplets preferably have a particle size distribution of usually 50% by volume or more, preferably 60% by volume or more, within the range of the volume average particle size ± 1 μm. In the case of suspension polymerization, after forming droplets of the polymerizable monomer composition in an aqueous dispersion medium containing a dispersion stabilizer in another container (that is, after the granulation step), the resulting suspension is obtained. It is preferable that the liquid is charged into a polymerization reactor and polymerization is performed in order to suppress generation of scale and coarse particles.

In the present invention, after the granulation step of the polymerizable monomer composition, suspension polymerization of the polymerizable monomer composition is performed in the presence of an oil-soluble polymerization initiator in the first stage polymerization step. In the first-stage polymerization step, the polymerization conversion of the polymerizable monomer is 30 to 97%,
Preferably 50-95%, more preferably 60-90%
The polymerization is carried out until. The reason for using an oil-soluble polymerization initiator in the first-stage polymerization step is that the oil-soluble polymerization initiator has excellent compatibility with the polymerizable monomer, and the polymerization reaction can proceed from the inside of the droplet. is there. When a reducing agent for redox initiator is added at this stage, the polymerization reaction proceeds from the surface of the droplets and a film is formed. As a result, the volume of the produced polymer particles shrinks or the shape becomes irregular. Therefore, it is difficult to obtain a spherical polymerized toner having a desired particle size and particle size distribution.

On the other hand, if the polymerization conversion rate in this pre-polymerization step is too high, the release agent bleeds on the surface of the resulting polymer particles. The low melting point release agent has good affinity with the polymerizable monomer, but has low affinity with the high melting point polymer. Therefore, as the polymerization of the polymerizable monomer proceeds by suspension polymerization, the release agent bleeds on the surface of the polymer particles. When the release agent bleeds on the surface of the polymer particles, the storage stability (blocking resistance) of the resulting polymerized toner is reduced and the image quality is reduced. If the release agent bleeds in large quantities, the effect of lowering the fixing temperature may be impaired.

In the second polymerization step, when the polymerization conversion in the first polymerization step reaches 30 to 97%, a reducing agent for a redox initiator is added to the reaction system to continue the polymerization reaction.
In the latter polymerization step, the polymerization reaction by the oil-soluble polymerization initiator from the inside of the droplet of the polymerizable monomer composition further proceeds, and near the surface of the droplet, the oil-soluble polymerization initiator and the redox initiator are used. The redox polymerization reaction proceeds by the action of the reducing agent. It is presumed that when the redox polymerization reaction proceeds from near the surface of the droplet, a polymer film is formed on the surface of the droplet, thereby preventing bleeding of the release agent. If the polymerization conversion rate in the first-stage polymerization step is too high, the bleeding of the release agent during the polymerization may proceed too much, and even if a polymer film is formed by a redox polymerization reaction in the second-stage polymerization step, the bleeding of the release agent may occur. It becomes difficult to control. If the polymerization conversion rate in the first-stage polymerization step is too low, the volume of the polymer particles to be formed shrinks due to the formation of the polymer film on the surface of the droplet, and it becomes difficult to control the particle size and the particle size distribution. In addition, the polymer particles are deformed and the fluidity of the polymerized toner is impaired.

The suspension polymerization is usually carried out at a temperature of 5 to 120 ° C., preferably 35 to 90 ° C. If the polymerization temperature is too low, it is necessary to use a polymerization initiator having a high catalytic activity, so that it becomes difficult to control the polymerization reaction. Conversely, if the polymerization temperature is too high, the release agent tends to bleed on the surface of the polymer particles, which is not preferable. According to the production method of the present invention, a polymer film is formed on the surface, and a polymer toner containing a low-melting-point release agent can be obtained, so that the fixing temperature is low and the storage stability (blocking resistance ) And a polymerized toner having excellent fluidity can be obtained.

The fixing temperature can be further lowered by using a polymerizable monomer capable of forming a polymer having a low glass transition temperature. However, in this case, since the polymer film is also formed from a polymer having a low melting point, the storage stability of the polymerized toner may be reduced. This problem can be solved by including a macromonomer in the polymerizable monomer composition. In general, macromonomers have a high glass transition temperature and can introduce a physically crosslinked structure into the resulting copolymer.
In addition, when a hydrophilic macromonomer is used, the macromonomer is likely to be contained as a copolymer component in the film when a polymer film is formed by a redox polymerization reaction. Therefore, by using the macromonomer in the production method of the present invention, the preservability of the polymerized toner can be further enhanced without impairing the fixing characteristics.

As another method for further improving the storage stability of the polymerized toner, the production of a polymerized toner having a core-shell structure according to the second invention of the present application is effective. That is, in the second invention, instead of using the colored polymer particles (a) obtained in the first invention as a polymerized toner as it is, a layer (shell) made of a polymer having a high glass transition temperature is coated on the surface thereof. As a result, the anti-blocking property can be increased, and the storability can be further improved. In order to form the shell, a polymerizable monomer for shell capable of forming a polymer having a glass transition temperature higher than the glass transition temperature of the polymer component constituting the colored polymer particles (a) is used. When the polymerizable monomer for shell is subjected to suspension polymerization in the presence of the colored polymer particles (a), the colored polymer particles (a) serving as core particles are obtained.
To obtain colored polymer particles (b) having a shell formed on the surface thereof. The colored polymer particles (b) are a core-shell type polymerized toner.

In the second invention of the present application, the step of forming a shell can be performed following the step of the first invention.
In this case, in the production process of the core particles, the polymerization reaction is continued until the polymerization conversion rate becomes 95% or more, preferably 97% or more, more preferably 99% or more in the subsequent polymerization step using the reducing agent for redox initiator. Then, an aqueous dispersion medium containing the colored polymer particles (a) is obtained, and the polymerizable monomer for shell is added thereto, and the polymerization reaction is further continued. In the production process of the core particles, in the pre-polymerization step using an oil-soluble polymerization initiator, when the polymerization conversion is already 95% or more, in the post-polymerization step using a reducing agent for a redox initiator, , Usually 0.5 to 15 hours, preferably 1 to
After the polymerization reaction is continued within 10 hours to further increase the polymerization conversion rate, the polymerizable monomer for shell is added, and the polymerization reaction is further continued. When the polymerization conversion of the polymerizable monomer forming the core particles is too low and the polymerization is continued by adding the polymerizable monomer for shell, the formation of the polymer film by the redox polymerization reaction on the surface of the core particles is sufficient. In addition, a copolymer of a polymerizable monomer for forming core particles and a polymerizable monomer for a shell is generated, and it becomes difficult to form a shell having a high glass transition temperature.

Since the colored polymer particles (a) are formed with a polymer film containing a release agent, a shell having a high glass transition temperature is formed thereon, whereby the blocking resistance is further improved. I do. Further, since the thickness of the shell can be reduced by the presence of the polymer film, the formation of the shell does not adversely affect the fixing temperature. The composition of the shell and the method of forming the shell will be described later in detail.

(Polymerizable monomer) In the present invention, a vinyl monomer is usually used as the polymerizable monomer. As the vinyl monomer, for example, styrene, vinyl toluene,
styrene monomers such as α-methylstyrene; acrylic acid, methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, dimethylaminoethyl acrylate, methyl methacrylate, Ethyl methacrylate, propyl methacrylate, butyl methacrylate, methacrylic acid 2
-Derivatives of acrylic acid or methacrylic acid such as ethylhexyl, dimethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide; ethylenically unsaturated monoolefins such as ethylene, propylene and butylene; vinyl chloride, vinylidene chloride, fluorine Vinyl halides such as vinyl acetate; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone and methyl isopropenyl ketone; 2-vinyl pyridine and 4-vinyl Monovinyl monomers such as nitrogen-containing vinyl compounds such as pyridine and N-vinylpyrrolidone;

These vinyl monomers may be used alone or in combination of a plurality of monomers.
Among these vinyl monomers, styrene monomers and derivatives of acrylic acid or methacrylic acid are preferably used. In particular, the combination of styrene and acrylate, such as styrene and butyl acrylate (i.e., n-butyl acrylate) and styrene and 2-ethylhexyl acrylate (i.e., 2-ethylhexyl acrylate), has a glass transition temperature of the polymer particles. Is easily adjusted to a desired range, and a polymerized toner having good characteristics is easily obtained. As the polymerizable monomer for the shell, a polymerizable monomer capable of forming a polymer having a glass transition temperature higher than the glass transition temperature of the polymer component constituting the core particles is used.

(Crosslinkable monomer) Along with the vinyl monomer,
Use of a crosslinkable monomer is effective for blocking resistance, offset prevention, and the like. As the crosslinkable monomer, a compound having two or more polymerizable carbon-carbon double bonds is usually used. Examples of the crosslinking monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; diethylenically unsaturated carboxylic esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; N, N
-Divinyl compounds such as divinylaniline and divinyl ether; compounds having three or more vinyl groups; These crosslinkable monomers can be used alone or in combination of two or more. The crosslinking monomer is used in an amount of usually 0.1 to 5 parts by weight, preferably 0.3 to 2 parts by weight, based on 100 parts by weight of the vinyl monomer. If the amount of the crosslinkable monomer used is too large, the amount of toluene insoluble in the polymerized toner becomes too large, and the fixability tends to decrease.

(Macromonomer) In the present invention, the macromonomer is copolymerized with a polymerizable monomer (vinyl monomer) in order to improve the balance between storage stability and low-temperature fixability of the polymerized toner. Preferred. In order to copolymerize the macromonomer, the macromonomer is included in the polymerizable monomer composition together with a colorant, a polymerizable monomer, a release agent, and the like. Macromonomers (also called macromers)
A relatively long linear molecule having a polymerizable functional group (for example, an unsaturated group such as a carbon-carbon double bond) at the end of a molecular chain. As the macromonomer, an oligomer or polymer having a vinyl polymerizable functional group at the terminal of the molecular chain and having a number average molecular weight of usually 1,000 to 30,000 is preferable. When a macromonomer having a too small number average molecular weight is used, the surface portion of the polymer particles tends to be soft and the storage stability tends to decrease. When a macromonomer having a too large number average molecular weight is used, the meltability of the macromonomer is lowered, and the low-temperature fixability is lowered. Examples of the vinyl polymerizable functional group at the terminal of the macromonomer molecular chain include an acryloyl group and a methacryloyl group, and a methacryloyl group is preferable from the viewpoint of easy copolymerization.

The macromonomer used in the present invention preferably has a glass transition temperature (Tg) higher than the glass transition temperature of the polymer obtained by polymerizing the polymerizable monomer. The level of Tg between the polymer obtained by polymerizing the polymerizable monomer and the macromonomer is relative.
For example, when the polymerizable monomer forms a polymer having a Tg of 70 ° C., the macromonomer has a Tg of 70 ° C.
What is necessary is just a thing over ℃. The polymerizable monomer is Tg = 5
In the case of forming a polymer at 0 ° C., the macromonomer may have a Tg of 60 ° C., for example. The Tg of the macromonomer used in the present invention is 80 ° C.
It is particularly preferable that the above is satisfied. Tg of macromonomer
Is a value measured by a measuring instrument such as a normal differential scanning calorimeter (DSC).

Specific examples of the macromonomer include styrene, styrene derivatives, methacrylates, acrylates, acrylonitrile, methacrylonitrile, and the like, or a polymer obtained by polymerizing two or more kinds;
Macromonomer having polysiloxane skeleton;
And those disclosed on pages 4 to 7 of JP-A-203746. Among these macromonomers, polymers obtained by polymerizing hydrophilic ones, particularly methacrylic esters or acrylic esters, alone or in combination, are suitable for the present invention. When using a macromonomer, the amount used is
Usually, 0.01 to 100 parts by weight of the polymerizable monomer.
It is 10 parts by weight, preferably 0.02 to 5 parts by weight, more preferably 0.03 to 1 part by weight. If the amount of the macromonomer is too small, the effect of improving the storage stability is small. If the amount of the macromonomer is too large, the low-temperature fixability will decrease.

(Molecular Weight Adjusting Agent) In the present invention, a molecular weight adjusting agent can be used if necessary. Examples of the molecular weight modifier include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, and n-octyl mercaptan; and halogenated hydrocarbons such as carbon tetrachloride and carbon tetrabromide. The molecular weight modifier is usually used by being included in the polymerizable monomer composition before the start of the polymerization, but may be added to the reaction system during the polymerization in some cases. The molecular weight modifier is usually 0.00.0 parts by weight per 100 parts by weight of the polymerizable monomer.
It is used in a proportion of 1 to 10 parts by weight, preferably 0.1 to 5 parts by weight.

(Releasing Agent) Examples of the releasing agent include polyfunctional ester compounds such as pentaerythritol tetrastearate and pentaerythritol tetramyristate; low molecular weight polyethylene, low molecular weight polypropylene,
Low molecular weight polyolefins such as low molecular weight polybutylene; paraffin waxes; Among these, those having a melting point in the range of 60 to 100 ° C are preferable. As the release agent, ordinary waxes can be used, but a polyfunctional ester compound formed from a polyhydric alcohol having three or more functional groups and a carboxylic acid is more preferable.

Examples of the trihydric or higher polyhydric alcohol include aliphatic alcohols such as glycerin, pentaerythritol and pentaglycerol; alicyclic alcohols such as phloroglucitol, quercitol and inositol; tris (hydroxymethyl) benzene Aromatic alcohols; D-erythrose, L-arabinose,
Sugars such as D-mannose, D-galactose, D-fructose, L-rhamnose, saccharose, maltose, lactose; sugar alcohols such as erythritol, D-trait, L-arabit, adnit, xylit; Among these, pentaerythritol is preferred.

Examples of the carboxylic acid include acetic acid, butyric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, stearic acid, margaric acid, arachidic acid, cerotic acid, Aliphatic carboxylic acids such as melixic acid, ericic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, behenylic acid, tetrolic acid, xymenic acid; cyclohexanecarboxylic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, 3,4 Alicyclic carboxylic acids such as 5,5,6-tetrahydrophthalic acid; aromatic carboxylic acids such as benzoic acid, toluic acid, cumic acid, phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, trimellitic acid, hemimelitic acid; Can be mentioned. Among them, carboxylic acids having preferably 10 to 30 carbon atoms, more preferably 13 to 25 carbon atoms are suitable, and aliphatic carboxylic acids having the carbon atoms are more preferable. Of the aliphatic carboxylic acids, stearic acid and myristic acid are particularly preferred. As the polyfunctional ester compound, a compound represented by the formula (I)

[0045]

Embedded image (However, R ¹ , R ² , R ³ , and R ⁴ are each independently an alkyl group or a phenyl group, and the alkyl group or the phenyl group preferably has 10 to 30 carbon atoms.
More preferably, the number is 13 to 25. ) Is preferred.

Specific examples of the polyfunctional ester compound include:
Pentaerythritol tetrastearate [Formula (I)
In the formula, all of R ¹ , R ² , R ³ and R ⁴ are CH ₃ (C
H _{2) 16} groups are compounds], in pentaerythritol myristate [Formula ^{(I), R 1, R} 2, R 3, and R ⁴
Are CH ₃ (CH ₂ ) ₁₂ groups, and glycerol triaraquinic acid. It is preferable that the polyfunctional ester compound be easily soluble in the polymerizable monomer. Among the polyfunctional ester compounds, pentaerythritol tetrastearate and pentaerythritol tetramyristate are particularly preferable, and pentaerythritol tetramyristate is particularly preferable. Normal waxes need to be crushed or melted and dispersed when mixed with a polymerizable monomer, but among polyfunctional ester compounds, pentaerythritol tetramyristate and the like are polymerizable. Since it is easily dissolved in the monomer even at room temperature, the adjustment of the polymerizable monomer composition is simple, and a polymerized toner excellent in various properties can be obtained. The release agent is used in an amount of usually 0.1 to 40 parts by weight, preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight, based on 100 parts by weight of the polymerizable monomer. If the amount of the release agent is too small, the low-temperature fixability cannot be sufficiently improved, and if it is too large, the blocking resistance decreases.

(Colorant) Examples of the colorant include carbon black, titanium white, nigrosine base, aniline blue, calco oil blue, chrome yellow,
Dyes and pigments such as Ultramarine Blue, Orient Oil Red, Phthalocyanine Blue, Malachite Green Oxalate; magnetic particles such as cobalt, nickel, iron sesquioxide, ferric oxide, iron manganese oxide, iron zinc oxide, nickel iron oxide And the like. In addition to these, various coloring agents as described below can be used. Examples of the colorant for a magnetic color toner include C.I. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Modant Red 30, C.I. I. Direct Blue 1,
C. I. Direct Blue 2, C.I. I. Acid Blue 9, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. Modant Blue 7, C.I. I. Direct Green 6, C.I.
I. Basic Green 4, C.I. I. Basic Green 6 and the like.

Examples of the pigment include, for example, graphite, cadmium yellow, mineral first yellow, navel yellow, nephtol yellow S, Hanza yellow G, permanent yellow NCG, tartrazine lake, red lead graphite, molybdenum orange, and permanent orange GT.
R, pyrazolone orange, benzidine orange G, cadmium red, permanent red 4R, watching red calcium salt, eosin lake, brilliant carmine 3B, manganese purple, fast violet B, methyl violet lake, navy blue, cobalt blue, alkaline blue lake, Victoria blue Lake, phthalocyanine blue, fast sky blue, induslen blue BC, chrome green, chromium oxide, pigment green B, malachite green lake, final yellow green G, and the like.

Examples of the magenta coloring pigment for full-color toner include C.I. I. Pigment Red 1, 2, 3,
4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 1
4, 15, 16, 17, 18, 19, 21, 22, 2,
3, 30, 31, 32, 37, 38, 39, 40, 4,
1, 48, 49, 50, 51, 52, 53, 54, 5
5, 57, 58, 60, 63, 64, 68, 81, 8
3, 87, 88, 89, 90, 112, 114, 12
2, 123, 163, 202, 206, 207, and 2
09; I. Pigment Violet 19; I.
Buttlets 1, 2, 10, 13, 15, 23, 29,
And 35;

Examples of the magenta dye include C.I. I.
Solvent Red 1, 3, 8, 23, 24, 25, 2
7, 30, 49, 81, 82, 83, 84, 100, 1,
09 and 121; I. Disperse thread 9;
C. I. Solvent Violet 8, 13, 14, 2
1, and 27; I. Disperse Violet 1;
And other oil-soluble dyes. Examples of the magenta dye include C.I. I. Basic Red 1, 2,
9, 12, 13, 14, 15, 17, 18, 22, 2,
3, 24, 27, 29, 32, 34, 35, 36, 3
7, 38, 39, and 40; I. Basic violet 1, 3, 7, 10, 14, 15, 21, 25, 2
And basic dyes such as 6, 27 and 28;

As the cyan coloring pigment for full-color toner, for example, C.I. I. Pigment Blue 2, 3, 15,
C. 16, and 17; I. Bat blue 6; I. Acid Blue 45; and a copper phthalocyanine pigment in which 1 to 5 phthalimidomethyl groups are substituted on the phthalocyanine skeleton. As the yellow color pigment for full-color toner, for example, C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 1
3, 14, 15, 16, 17, 23, 65, 73, 8
3, 138, and 180; I. Bat Yellow 1,
3, and 20; and the like. Of these colorants, dyes and pigments are based on 100 parts by weight of the polymerizable monomer.
Usually, it is used in a ratio of 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight. The magnetic particles are composed of polymerizable monomer 10
It is used in an amount of usually 1 to 100 parts by weight, preferably 5 to 50 parts by weight, based on 0 parts by weight.

(Lubricant / Dispersion Aid) Various olefinic lubricants such as oleic acid, stearic acid, various waxes, polyethylene, polypropylene, etc .; May be used. Such a lubricant or dispersant is usually 1/100 based on the weight of the colorant.
It is used at a ratio of about 0 to 1/1. When the release agent and the lubricant are the same, it is not necessary to add a lubricant.

(Charge Control Agent) In the present invention, a charge control agent can be used, if necessary, to control the chargeability of the polymerized toner. As the charge control agent, a commonly used positive charge control agent or negative charge control agent can be used. Specific examples of the charge control agent include a metal complex of an organic compound having a carboxyl group or a nitrogen-containing group, a metal-containing dye, and nigrosine.
More specifically, Spiron Black TRH (Hodogaya Chemical Co., Ltd.), T-77 (Hodogaya Chemical Co., Ltd.), Bontron S-34 (Orient Chemical Co., Ltd.), Bontron E-84
(Orient Chemical), Bontron N-01 (Orient Chemical), Copy Blue-PR (Hoechst)
And the like. The charge control agent is
Usually, 0.01 to 1 based on 100 parts by weight of the polymerizable monomer.
0 parts by weight, preferably 0.03 to 5 parts by weight.

(Oil-Soluble Polymerization Initiator) Illustrative examples of the oil-soluble polymerization initiator together with a 10-hour half-life temperature (shown in parentheses) include isobutyl peroxide (3
Diacyl peroxides such as 3 ° C.), 2,4-di-chlorobenzoyl peroxide (53 ° C.), and 3,5,5-trimethylhexanoyl peroxide (59 ° C.);
Bis (4-t-butylcyclohexyl) peroxydi-
Carbonate (41 ° C), di-n-propylperoxydi-carbonate (40 ° C), di-isopropylperoxydi-carbonate (41 ° C), di-2-ethoxyethylperoxydi-carbonate (43 ° C), Di (2-
Ethyl ethyl peroxy) di-carbonate (44
Peroxy di-carbonates such as di-methoxybutylperoxydi-carbonate (46 ° C), di (3-methyl-3-methoxybutylperoxy) di-carbonate (47 ° C); (α, α-bis -Neodecanoylperoxy) diisopropylbenzene (36 ° C), cumylperoxy neodecanoate (37 ° C), 1,1,3,
3-tetramethylbutyl peroxy neodecanoate (41 ° C.), 1-cyclohexyl-1-methylethyl peroxy neodecanoate (41 ° C.), t-hexyl peroxy neodecanoate (45 ° C.), t -Butyl peroxy neodecanoate (46 ° C.), t-hexyl peroxy pivalate (53 ° C.), t-butyl peroxy pivalate (53 ° C.), t-butyl peroxy pivalate (55 ° C.), etc. Peroxyesters; and the like.

As the oil-soluble polymerization initiator, 2,2
And azo compounds such as -azobis (4-methoxy-2,4-dimethylvaleronitrile (30 ° C) and 2,2-azobis (2,4-dimethylvaleronitrile) (51 ° C). Among the polymerization initiators, those having a 10-hour half-life temperature of 60 ° C. or less are preferred,
The thing of 0 degreeC is more preferable, and the thing of 45-55 degreeC is especially preferable. Further, among the oil-soluble polymerization initiators, peroxyesters are preferable since they have low odor and little deactivation of the reaction even in the presence of a coloring agent. The amount of the oil-soluble initiator used is usually 0.001 to 3 based on the aqueous medium.
% By weight. If the amount of the oil-soluble initiator used is too small,
If the polymerization rate is too slow and too high, the molecular weight will be low, which is not preferred.

(Redox Initiator) The Redox initiator is an initiator system which generates radicals by a reaction between an oxidizing agent and a reducing agent. In the present invention, in the latter polymerization step, the reducing agent used for the redox initiator is added to the reaction system to continue the polymerization reaction. The redox initiator reducing agent used in the present invention includes, for example, Fe ²⁺ salt (for example, ferrous sulfate), Cu ⁺ salt, Cr ²⁺ salt, V
²⁺ salt, Ti ³⁺ salt, sulfite (eg, sodium sulfite, sodium bisulfite), ammonia, amine, hydroxylamine, hydrazine, alcohol and the like. As the reducing agent, in addition to the above, -SH, -SO
_An organic compound containing a group such as ₂ H, —NHNH ₂ , or —COCH (OH) — (for example, sodium formaldehyde sulfoxylate) or the like is used. When a metal ion such as ferrous ion is used as a reducing agent, it is preferable to form a complex using a chelating agent. Examples of the chelating agent include disodium ethylenediaminetetraacetate, and specific examples of the complex include sodium iron ethylenediaminetetraacetate. The amount of the redox initiator reducing agent used is usually 0.001 to 3 based on the aqueous medium.
% By weight. If the amount of the reducing agent for the redox initiator is too small, the polymerization rate becomes slow, and if it is too large, the molecular weight becomes low, which is not preferable.

(Dispersion Stabilizer) The suspension polymerization is carried out in an aqueous dispersion medium containing a dispersion stabilizer. Specifically, a ball mill is prepared by mixing a polymerizable monomer (vinyl-based monomer), a release agent, a colorant, a macromonomer selected as required, a crosslinkable monomer, and other additives. A liquid mixture (polymerizable monomer composition) is prepared by uniformly dispersing the mixture liquid and the like, and then the mixed liquid is poured into an aqueous dispersion medium containing a dispersant,
After dispersing using a mixing device having high shearing force and granulating into fine droplets, in the former polymerization step, in the presence of the oil-soluble polymerization initiator, in the latter polymerization step, the reducing agent for the redox initiator is also used. The suspension polymerization is carried out in the presence. The mixture may contain an oil-soluble polymerization initiator in advance, but after the mixture containing no oil-soluble polymerization initiator is introduced into the aqueous dispersion medium, the mixture is granulated into fine droplets. Before the addition, the oil-soluble polymerization initiator is charged with stirring, contained in the mixed solution in the aqueous dispersion medium, and then granulated into fine droplets using a mixing device having a high shear force. Is preferred.

The dispersion stabilizer suitably used in the present invention includes:
It is a colloid of a poorly water-soluble metal compound. Examples of poorly water-soluble metal compounds include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide ;
Metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; and the like. Of these, colloids of poorly water-soluble metal hydroxides are preferred because they can narrow the particle size distribution of the polymer particles and improve the sharpness of the image.

The colloid of the poorly water-soluble metal hydroxide is not limited by the production method, but the colloid of the poorly water-soluble metal hydroxide obtained by adjusting the pH of the aqueous solution of the water-soluble polyvalent metal compound to 7 or more is used. Colloids, especially colloids of poorly water-soluble metal hydroxides formed by the reaction of a water-soluble polyvalent metal compound with an alkali metal hydroxide in an aqueous phase are preferred. Colloids of poorly water-soluble metal hydroxides are used as aqueous dispersions. The colloid of the poorly water-soluble metal compound used in the present invention has a number particle size distribution D ₅₀ (50% cumulative value of the number particle size distribution) of 0.5 μm or less and a D ₉₀ (90% cumulative of the number particle size distribution). Value) is preferably 1 μm or less. If the particle size of the colloid is too large, the stability of the polymerization reaction system is lost, and the storage stability of the polymerized toner is also reduced.

The dispersion stabilizer is usually used in a proportion of 0.1 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer.
If the use ratio of the dispersion stabilizer is too small, it is difficult to obtain sufficient polymerization stability, and a polymer aggregate is easily generated. Conversely, if the use ratio of the dispersion stabilizer is too large, the effect of the polymerization stability is saturated, and in addition to being uneconomical, the viscosity of the aqueous dispersion medium is too high, and the fineness of the polymerizable monomer composition is small. It is difficult to form a proper droplet. In the present invention, a water-soluble polymer can be used as a dispersion stabilizer, if necessary. Examples of the water-soluble polymer include polyvinyl alcohol, methyl cellulose, gelatin and the like. In the present invention, it is not necessary to use a surfactant, but it can be used for stably performing polymerization as long as the environment dependence of the charging characteristics of the polymerized toner does not increase.

(Shell) In the present invention, the core-shell type polymerized toner can be obtained by polymerizing a polymerizable monomer for shell in the presence of the colored polymer (a) serving as core particles. The colored polymer (a) serving as the core particle is a polymer particle obtained by the production method of the first invention of the present application. The polymerizable monomer for shell used in the present invention is capable of forming a polymer having a glass transition temperature higher than the glass transition temperature of the polymer component constituting the core particles. The level of Tg between the polymer obtained from the polymerizable monomer for shell and the polymer component constituting the core particle is relative.

As the polymerizable monomer for shell, for example, a polymerizable monomer such as styrene or methyl methacrylate which forms a polymer having a glass transition temperature exceeding 80 ° C. is used alone or in combination of two or more. Can be used. When the glass transition temperature of the polymer component of the core particle is much lower than 80 ° C., the polymerizable monomer for shell may form a polymer having a temperature of 80 ° C. or lower. It is necessary to set the glass transition temperature of the polymer comprising the polymerizable monomer for shell to be higher than at least the glass transition temperature of the polymer component of the core particles. The glass transition temperature of the polymer obtained from the polymerizable monomer for shell is usually 5 to improve the storage stability of the polymerized toner.
The temperature is 0 to 120C, preferably 60 to 115C, more preferably 80 to 110C. If the glass transition temperature of the polymer composed of the polymerizable monomer for shell is too low, the storage stability of the polymerized toner deteriorates even if the glass transition temperature is higher than the glass transition temperature of the polymer component of the core particles. May be. In many cases, the glass transition temperature of the polymer component of the core particles can be represented by a calculated Tg of a polymer formed from the polymerizable monomer for the core. here,
The polymerizable monomer for a core is a polymerizable monomer used for forming the colored polymer (a) serving as the core particles described above.

The difference in the glass transition temperature between the polymer composed of the polymerizable monomer for the core and the polymer composed of the polymerizable monomer for the shell is usually 10 ° C. or higher, preferably 20 ° C. or higher.
It is more preferably at least 30 ° C. When polymerizing the shell polymerizable monomer in the presence of the core particles, it is preferable that the polymerizable monomer be a droplet smaller than the number average particle diameter of the core particles in the aqueous dispersion medium. When the particle size of the droplet of the polymerizable monomer for shell increases, the storage stability of the core-shell type polymerized toner tends to decrease. In order to make the shell polymerizable monomer into small droplets, a mixture of the shell polymerizable monomer and the aqueous dispersion medium is finely dispersed using, for example, an ultrasonic emulsifier. The aqueous dispersion thus obtained is
It is preferable to add to the reaction system in which the core particles exist.

The polymerizable monomer for shell is not particularly limited by the solubility in water at 20 ° C., but the monomer having high solubility in water, specifically, the solubility in water at 20 ° C. is 0.1% by weight. Since the above-mentioned monomers easily move to the surface of the core particles quickly, it is easy to obtain a polymerized toner having good storability. On the other hand, 20 ° C.
When a monomer having a solubility in water of less than 0.1% by weight is used, the migration to the surface of the core particle becomes slow. Is preferred. Even when a monomer having a solubility in water at 20 ° C. of less than 0.1% by weight is used, an organic solvent having a solubility in water at 20 ° C. of 5% by weight or more is added to the reaction system to form a polymerizable monomer for shell. The monomer is quickly transferred to the surface of the core particle, and it becomes easy to obtain a polymer particle having good storability.

The solubility in water at 20 ° C. is 0.1% by weight.
Examples of the shell polymerizable monomer of less than styrene include styrene, butyl acrylate, 2-ethylhexyl acrylate, ethylene, and propylene. Monomers having a solubility in water at 20 ° C. of 0.1% by weight or more include (meth) acrylates such as methyl methacrylate and methyl acrylate; amides such as acrylamide and methacrylamide; and cyanides such as acrylonitrile and methacrylonitrile. Vinyl compounds; nitrogen-containing vinyl compounds such as 4-vinylpyridine; vinyl acetate, acrolein and the like. Organic solvents that are preferably used when a shell monomer having a solubility in water at 20 ° C. of less than 0.1% by weight include methanol, ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol and the like. Lower alcohols; ketones such as acetone and methyl ethyl ketone; cyclic ethers such as tetrahydrofuran and dioxane; ethers such as dimethyl ether and diethyl ether; amides such as dimethylformaldehyde.

The organic solvent has a solubility of the polymerizable monomer for shell in a dispersion medium (total amount of water and the organic solvent) of 0.1.
It is added in an amount ratio of 1% by weight or more. The specific amount of the organic solvent varies depending on the type of the organic solvent and the type and amount of the polymerizable monomer for the shell, but is usually 0.1 to 50 parts by weight, preferably 100 parts by weight, based on 100 parts by weight of the aqueous dispersion medium. Is 0.1
-40 parts by weight, more preferably 0.1-30 parts by weight. The order in which the organic solvent and the shell polymerizable monomer are added to the reaction system is not particularly limited, and the transfer of the shell polymerizable monomer to the core particles is promoted to obtain a polymer toner having good storage stability. It is preferable to add an organic solvent first and then add a polymerizable monomer for a shell, for ease of use.

The solubility in water at 20 ° C. is 0.1% by weight.
When a monomer having less than 0.1% by weight and a monomer having a solubility of less than 0.1% by weight are used in combination, a monomer having a solubility in water at 20 ° C. of 0.1% by weight or more is added, followed by polymerization. After adding the organic solvent, the solubility in water at 20 ° C. is 0.1% by weight.
It is preferred to add less than the monomers and polymerize. According to this addition method, in order to adjust the fixing temperature of the polymerized toner, it is possible to appropriately control the Tg of the polymer obtained from the monomer polymerized in the presence of the core particles and the amount of the monomer added. it can. The polymerizable monomer for shell is preferably used by mixing a charge control agent. When a charge control agent is contained in the shell, the chargeability of the polymerized toner can be improved. As the charge control agent, various positively or negatively chargeable charge control agents as described above can be used. The charge control agent is used in an amount of usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer for shell.

As a specific method for polymerizing the polymerizable monomer for shell in the presence of the core particles, a polymerizable monomer for shell is added to the reaction system of the polymerization reaction performed to obtain the core particles. Then, a method of continuously polymerizing or a method of charging core particles obtained in another reaction system, adding a polymerizable monomer for shell to the core particles, and polymerizing stepwise can be exemplified. The polymerizable monomer for shell can be added to the reaction system at once, or can be added continuously or continuously using a pump such as a plunger pump.
When adding the polymerizable monomer for shell, it is preferable to add a water-soluble radical initiator in order to easily obtain core-shell type polymer particles. When adding a water-soluble radical initiator during the addition of the polymerizable monomer for shell,
It is considered that the reason is that the water-soluble radical initiator enters the vicinity of the outer surface of the core particles to which the polymerizable monomer for the shell has migrated, so that a polymer layer (shell) is easily formed on the surface of the core particles.

Examples of the water-soluble radical initiator include persulfates such as potassium persulfate and ammonium persulfate; 4,4-azobis (4-cyanovaleric acid), 2,2-azobis (2-
Amidinopropane) dihydrochloride, 2,2-azobis-2-
Methyl-N-1,1-bis (hydroxymethyl) -2-
Azo initiators such as hydroxyethylpropoamide; redox initiators comprising a combination of a peroxide such as cumene hydroperoxide and a reducing agent; and the like. The amount of the water-soluble radical initiator used is usually 0.001 to 1% by weight based on the aqueous medium. In the core-shell type polymerized toner of the present invention, the weight ratio of the core polymerizable monomer to the shell polymerizable monomer is usually from 40/60 to 99.9 / 0.1, and preferably from 40/60 to 99.9 / 0.1. 60 /
40 to 99.5 / 0.5, more preferably 80/20 to
99/1. If the ratio of the shell monomer is too small, the effect of improving the storage stability is small, and if it is too large,
The effect of reducing the fixing temperature is reduced.

(Polymerized Toner) The polymerized toner of the present invention has a volume average particle size (dv) of usually 2 to 20 μm, preferably 3 to 15 μm, and a particle size distribution, that is, a product average particle size (d).
v) and the number average particle size (dp) ratio (dv / dp) is
The particles are generally 1.7 or less, preferably 1.6 or less, more preferably 1.5 or less, spherical fine particles having a sharp particle size distribution. In the core-shell type polymerized toner of the present invention, the average thickness of the shell is usually 0.001 to 1.0 μm.
m, preferably 0.005 to 0.5 μm. If the thickness of the shell is too large, the fixability at low temperatures is reduced, and if it is too small, the storage stability is reduced. When the core particle diameter and the shell thickness of the polymerized toner can be observed with an electron microscope, the core particle diameter and the shell thickness can be obtained by directly measuring the particle size and the shell thickness randomly selected from the observation photograph. If it is difficult to clearly observe the particle size of the core particles and the thickness of the shell with an electron microscope, measure the particle size of the core particles, determine the measured value and the amount of polymerizable monomer used to form the shell. Can be calculated from

The polymerized toner of the present invention has a toluene insoluble content of usually 50% by weight or less, preferably 20% by weight or less, more preferably 10% by weight or less. When the amount of insolubles in toluene increases, the fixability tends to decrease. Toluene-insoluble matter means that a polymer component forming a polymerized toner is placed in an 80-mesh wire mesh basket, immersed in toluene at room temperature for 24 hours, and the solid remaining in the basket is dried by a reduced-pressure drier and dried. The subsequent weight was measured and expressed as a percentage by weight based on the polymer component. In the polymerized toner of the present invention, the ratio of the major axis rl to the minor axis rs (rl / rs) is usually 1.00 to 1.25, preferably 1.00 to 1.20,
More preferably, it is 1.00 to 1.15. If this ratio is too large, the fluidity and image resolution will decrease,
Further, when the toner is stored in the toner storage section of the image forming apparatus, the friction between the toners increases, and thus the external additive tends to be peeled off, and the durability tends to decrease.

(Developer) The polymerized toner of the present invention is usually
The developer is used in combination with an external additive such as a fluidizing agent or an abrasive. When the external additive is added to and mixed with the polymerized toner, the external additive adheres to the surface of the polymerized toner. The external additive has the function of increasing the fluidity of the polymerized toner or suppressing the formation of a toner film on a photoreceptor by a polishing action. Representative external additives include inorganic particles and organic resin particles. Examples of the inorganic particles include silicon dioxide, aluminum oxide, titanium oxide, zinc oxide, tin oxide, barium titanate, and strontium titanate. As the organic resin particles, methacrylate polymer particles, acrylate polymer particles, styrene-methacrylate copolymer particles, styrene-
Acrylic ester copolymer particles, core-shell type particles in which the core is a methacrylate polymer and the shell is formed of a styrene polymer, and cores in which the core is a styrene polymer and the shell is formed of a methacrylic ester polymer -Shell-type particles and the like.

Of these, inorganic oxide particles, particularly silicon dioxide particles, are preferred. Moreover, the surface of these particles can be subjected to a hydrophobic treatment, and silicon dioxide particles subjected to the hydrophobic treatment are particularly suitable. The amount of the external additive is not particularly limited, but is usually based on 100 parts by weight of the polymerized toner.
0.1 to 6 parts by weight. External additives, each alone,
Alternatively, two or more kinds can be used in combination. When a plurality of external additives are used in combination, it is preferable to combine two types of inorganic oxide particles or organic resin particles having different average particle sizes. More specifically, small particles (preferably inorganic oxide particles) having an average particle diameter of 5 to 20 nm, preferably 7 to 18 nm, and large particles having an average particle diameter of more than 20 nm and 2 μm or less, preferably 30 nm to 1 μm (preferably Is preferably used in combination with inorganic oxide particles. The average particle diameter of the external additive is an average value obtained by observing the particles with a transmission electron microscope, randomly selecting 100 particles, and measuring the particle diameter.

The compounding amount of these two types of external additives is based on 100 parts by weight of the polymerized toner particles, and the average particle diameter is 5 to 20 nm.
Is usually 0.1 to 3 parts by weight, preferably 0.2 to 3 parts by weight.
Large particles having an average particle diameter of more than 20 nm and 2 μm or less are usually 0.1 to 3 parts by weight, preferably 0.2 to 2 parts by weight.
Parts by weight. The weight ratio of the small particles having an average particle diameter of 5 to 20 nm and the large particles having an average particle diameter of more than 20 nm and 2 μm or less is as follows:
Usually, in the range of 1: 5 to 5: 1, preferably 3:10 to 1
The range is 0: 3. By using these particles in combination, a developer having an excellent balance between fluidity and abrasiveness can be obtained. The attachment of the external additive to the polymerized toner is usually performed by stirring the external additive and the polymerized toner in a mixer such as a Henschel mixer. When the polymerized toner of the present invention is used, the fixing temperature is 80 to 150 ° C., preferably 80 to 150 ° C.
The temperature can be reduced to a low temperature of up to 130 ° C., and furthermore, it does not aggregate during storage and has excellent storage properties.

(Image Forming Apparatus) An image forming apparatus to which the polymerized toner of the present invention is applied is a photosensitive member (photosensitive drum), means for charging the surface of the photosensitive member, and forms an electrostatic latent image on the surface of the photosensitive member. Means, means for containing toner (developer), means for supplying toner to develop an electrostatic latent image on the surface of the photoreceptor to form a toner image, and transferring the toner image from the surface of the photoreceptor to a transfer material Means. FIG. 1 shows a specific example of such an image forming apparatus. As shown in FIG.
In the image forming apparatus, a photosensitive drum 1 as a photosensitive member is rotatably mounted in the direction of arrow A. The photosensitive drum 1 has a photoconductive layer provided on the outer peripheral surface of a conductive support drum. The photoconductive layer is composed of, for example, an organic photoconductor, a selenium photoconductor, a zinc oxide photoconductor, an amorphous silicon photoconductor.

Around the photosensitive drum 1, along a circumferential direction thereof, a charging roll 2 as a charging unit, a laser beam irradiation device 3 as a latent image forming unit, a developing roll 4 as a developing unit, and a transfer roll as a transferring unit. A transfer roll 10, a cleaning device (not shown), and the like are arranged as needed. The charging roll 2 is for uniformly charging the surface of the photosensitive drum 1 positively or negatively. The surface of the photosensitive drum 1 is charged by applying a voltage to the charging roll 2 and bringing the charging roll 2 into contact with the surface of the photosensitive drum 1. The charging roll 2 can be replaced with charging means using corona discharge.

The laser beam irradiating device 3 irradiates the surface of the photosensitive drum 1 with light corresponding to the image signal, and irradiates the uniformly charged surface of the photosensitive drum 1 with light in a predetermined pattern. This is for forming an electrostatic latent image on the irradiated portion (in the case of reversal development) or forming an electrostatic latent image on a portion not irradiated with light (in the case of regular development). As another latent image forming unit, there is a unit formed of an LED array and an optical system. The developing roll 4 is for attaching toner to the electrostatic latent image on the photosensitive drum 1. In the reversal development, the toner is attached only to the light-irradiated portion. A bias voltage is applied between the developing roll 4 and the photosensitive drum 1 so that the toner adheres.

A developing roll 4 and a supply roll 6 are provided in a casing 9 in which the toner 7 is stored.
The developing roll 4 is arranged close to and in contact with the photosensitive drum 1 so as to rotate in a direction B opposite to the photosensitive drum 1. The supply roll 6 contacts the developing roll 4 and rotates in the same direction C as the developing roll.
Is supplied to the outer periphery of the printer. A stirring means (stirring blade) 8 for stirring the toner is mounted in the casing 9. Around the developing roll 4, a developing roll blade 5 as a layer thickness regulating means is disposed at a position between a contact point with the supply roll 6 and a contact point with the photosensitive drum 1. The blade 5 is made of a conductive rubber or stainless steel, and normally performs charge injection into the toner.
Is applied. Therefore, the electrical resistivity of the blade 5 is preferably 10 6 Ωcm or less.

The polymerized toner 7 of the present invention is accommodated in the casing 9 of the image forming apparatus. The polymerized toner 7 may have an additive such as a fluidizing agent attached thereto. The polymerized toner of the present invention has a core-shell structure, and the shell of the surface layer is formed of a polymer having a relatively high glass transition temperature. Aggregation during storage is suppressed in 9. Further, since the polymerized toner of the present invention has a relatively sharp particle size distribution, when the toner layer is formed on the developing roll 4, it can be formed into a substantially single layer by the layer thickness regulating means 5, Thereby, the reproducibility of the image is improved.

The transfer roll 10 is for transferring the toner image formed on the surface of the photosensitive drum 1 by the developing roll 4 onto the transfer material 11. As the transfer material 11, paper,
A resin sheet such as an OHP sheet may be used. Examples of the transfer unit include a corona discharge device and a transfer belt in addition to the transfer roll 10. The toner image transferred onto the transfer material 11 is fixed on the transfer material by a fixing unit. The fixing unit usually includes a heating unit and a pressing unit. More specifically, the fixing unit is generally constituted by a combination of a heating roll (fixing roll) 12 and a pressure roll 13. Transfer material 11 on which the toner image has been transferred
Is passed between the heating roll 12 and the pressure roll 13 to melt the toner, and at the same time, is pressed and fixed on the transfer material 11.

In this image forming apparatus, since the polymerized toner of the present invention is used, the toner is easily melted even if the heating temperature by the heating means is low, and when pressed lightly by the pressure bonding means, the toner becomes smooth. Since it is fixed to the transfer material surface, printing or copying at high speed is possible. Also,
When a color toner is used, color mixing is easy. Further, the toner image fixed on the OHP sheet has excellent OHP transparency. The cleaning device is a photosensitive drum 1
This is for cleaning the transfer residual toner remaining on the surface of the printer, and is constituted by, for example, a cleaning blade. The cleaning device does not necessarily need to be installed in the case where a method of performing cleaning at the same time as development by the developing roll 4 is adopted.

(Image Forming Method) In the image forming method using the polymerized toner of the present invention, a toner is adhered to the surface of the photoreceptor on which the electrostatic latent image is formed to form a visible image, and then the visible image is formed. In the image forming method including the step of transferring the toner to a transfer material, the polymerized toner of the present invention is used as the toner.

[0083]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, parts and% are
Unless otherwise specified, it is based on weight.

The method for evaluating the characteristics of the developer (toner) is as follows. (1) Fluidity Three types of sieves each having an opening of 150 μm, 75 μm and 45 μm are stacked in this order from the top, and 4 g of the developer to be measured is precisely weighed and placed on the uppermost sieve. Then, the three kinds of the sifted screens were passed through a powder measuring device (trade name “REO” manufactured by Hosokawa Micron Co., Ltd.).
Using STAT "), the weight of the developer remaining on each sieve after vibration for 15 seconds under the condition of vibration intensity 4 is measured.
The values of a, b and c are calculated by substituting the measured values into the following formulas. Next, the values of a, b, and c are put into an equation to calculate the value of the fluidity. The measurement was performed three times per sample, and the average value was determined. Calculation formula: a = [weight of developer remaining on 150 μm sieve (g)] / 4 g × 100 b = [weight of developer remaining on 75 μm sieve (g)] / 4 g × 100 × 0.6 c = [45 μm sieve Developer remaining in (g)] / 4 g × 100 × 0.2 Fluidity (%) = 100− (a + b + c)

(2) Storage Property The developer is put in a sealable container, and after sealing, the container is immersed in a thermostatic water bath maintained at a temperature of 55 ° C. After a certain period of time, the container is taken out of the thermostatic bath, and the developer in the container is transferred onto a 42-mesh sieve. At this time, the developer is gently taken out of the container and carefully transferred to the sieve so as not to destroy the aggregated structure of the developer in the container.
This sieve was subjected to a vibration intensity of 4.5 using the aforementioned powder measuring device.
After vibrating for 30 seconds under the conditions described above, the weight of the developer remaining on the sieve was measured and defined as the weight of the aggregation developer. The ratio (% by weight) of the weight of the aggregation developer to the weight of the developer initially placed in the container was calculated. Measure three times per sample,
The average value was used as an index of conservation.

(3) Fixing Temperature A fixing test was performed using a commercially available non-magnetic one-component developing system printer (four-sheet machine) modified so that the temperature of the fixing roll can be changed. The fixing test was performed by changing the temperature of the fixing roll of the modified printer, measuring the fixing rate of the developer at each temperature, and obtaining the relationship between the temperature and the fixing rate. The fixation rate was calculated from the ratio of the image density before and after the tape peeling operation in the black solid area of the test paper printed by the modified printer. That is, assuming that the image density before tape removal is before ID and the image density after tape removal is after ID, the fixing rate can be calculated from the following equation. Fixing rate (%) = (after ID / before ID) × 100 Here, the tape peeling operation is to attach an adhesive tape (manufactured by Sumitomo 3M, Scotch Mending Tape 810-3-18) to the measurement portion of the test paper. This is a series of operations in which the adhesive tape is pressed and adhered at a constant pressure, and then the adhesive tape is peeled at a constant speed in a direction along the paper. The image density was measured using a Macbeth reflection densitometer. In this fixing test, the fixing roll temperature at a fixing rate of 80% was evaluated as the fixing temperature of the developer.

(4) Environmental Dependency Using the above-described modified printer, 35 ° C. × 80 RH%
(H / H) and 10 ° C. × 20 RH% (L / L) in each environment, continuous printing was performed from the beginning, and the print density measured by a reflection densitometer (manufactured by Macbeth) was 1.3 or more, and Fog in the non-image area measured by a whiteness meter (manufactured by Nippon Denshoku Co., Ltd.)
The number of continuous printed sheets capable of maintaining the image quality of 0% or less was examined, and the environmental dependency of the image quality by the developer was evaluated based on the following criteria. ：: 10,000 continuous prints capable of maintaining the above image quality
Δ: The number of continuous prints capable of maintaining the above image quality is 5,000 or more and less than 10,000, ×: The number of continuous prints capable of maintaining the above image quality is less than 5,000.

(5) Durability Continuous printing was carried out from the beginning in a room temperature environment of 23 ° C. × 50 RH% with the above-mentioned modified printer, and the print density measured with a reflection densitometer (manufactured by Macbeth) was 1.3 or more. The number of continuous prints that can maintain an image quality of 10% or less of fog in the non-image area measured by a whiteness meter (manufactured by Nippon Denshoku Co., Ltd.) is evaluated, and the durability of the image quality by the developer is evaluated based on the following criteria. did. ：: 10,000 continuous prints capable of maintaining the above image quality
Δ: The number of continuous prints capable of maintaining the above image quality is 5,000 or more and less than 10,000, ×: The number of continuous prints capable of maintaining the above image quality is less than 5,000.

(6) Particle Size The volume average particle size (dv) of the polymer particles, and the particle size distribution, ie, the ratio (dv) between the volume average particle size and the number average particle size (dp),
/ Dp) was measured with a Multisizer (Coulter). The measurement by the multisizer was performed under the conditions that the aperture diameter was 50 μm, the medium was Isoton II, the concentration was 10%, and the number of particles measured was 50,000.

(7) Shell Thickness In this example, the shell thickness was calculated using the following equation. Shell thickness (μm) = dr (1 + s / 100) ^1/3 −d
r where dr is the radius of the core particle before addition of the polymerizable monomer for shell (1/2 of the volume average particle size measured by a multisizer), and s is the polymerizable monomer for shell. It is the number of parts added to the monomer (parts based on 100 parts by weight of the core polymerizable monomer).

(8) Volume resistivity The volume resistivity of the polymer particles was measured using a dielectric loss meter (trade name “TRS-10” manufactured by Ando Electric Co., Ltd.) at a temperature of 3
The measurement was performed under the conditions of 0 ° C. and frequency = 1 kHz.

Example 1 (a) Preparation of Release Agent Dispersion 90 parts of styrene and 10 parts of a release agent (trade name “Paraffin Wax 155” manufactured by Nippon Seiwa Co., Ltd., melting point 70 ° C.) were mixed with a media-type wet method. The mixture was placed in a pulverizer and subjected to wet pulverization to obtain a dispersion in which the release agent was uniformly dispersed in styrene (solid content: 10%).
%) Was prepared. The volume average particle diameter of the releasing agent in the dispersion, D ₅₀ is at 2.8 .mu.m, D ₉₀ was 6.8 [mu] m.
The volume average particle size was measured by adding a sample to styrene, dispersing the sample by applying ultrasonic waves to form a dispersion, and then dropping the dispersion into a measurement cell filled with styrene, and measuring with a SALD-2000J (manufactured by Shimadzu Corporation). .

(B) Preparation of polymerizable monomer composition 40 parts of the release agent dispersion prepared in the above (a) (styrene 3
6 parts and 4 parts of release agent), 47 parts of styrene, 17 parts of n-butyl acrylate, 7 parts of carbon black (manufactured by Mitsubishi Chemical Corporation, product number “# 25B”), 0.3 parts of divinylbenzene
And 1.0 part of t-dodecyl mercaptan were stirred and mixed by a usual stirring device, and then charged into a media-type disperser to be uniformly dispersed to obtain a polymerizable monomer composition. This polymerizable monomer composition contains a total of 83 parts of styrene and 17 parts of n-butyl acrylate as polymerizable monomers, and has a calculated glass transition temperature (Tg) of 60 parts.
° C.

(C) Preparation of colloidal dispersion of poorly water-soluble metal hydroxide In an aqueous solution obtained by dissolving 10.2 parts of magnesium chloride (a water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water, and 50 parts of ion-exchanged water 5. Sodium hydroxide (alkali metal hydroxide)
An aqueous solution in which 2 parts were dissolved was gradually added under stirring to prepare a magnesium hydroxide colloid (poorly water-soluble metal hydroxide colloid) dispersion. The particle size distribution of the formed magnesium hydroxide colloid was measured using a micro-track particle size distribution measuring apparatus (manufactured by Nikkiso Co., Ltd.), D ₅₀ of 0.3
At 7 μm, D ₉₀ was 0.81 μm. The measurement with a Microtrac particle size distribution analyzer is as follows: measurement range = 0.1
The measurement was performed under the conditions of 2-704 μm, measurement time = 30 seconds, and medium = ion-exchanged water.

(D) Production of colored polymer particles The polymerizable monomer composition prepared in (b) is charged into the magnesium hydroxide colloid dispersion prepared in (c) above, and the droplets are stabilized. After stirring, 7 parts of t-butyl peroxy neodecanoate (manufactured by NOF CORPORATION, trade name "Perbutyl ND") as an oil-soluble polymerization initiator was added, and the mixture was stirred at 12,000 rpm using a TK homomixer. By high-shear stirring at a rotation speed, fine droplets of the polymerizable monomer composition were granulated. The particle size of the droplet is determined by comparing the obtained droplet with SALD-2.
Was measured at 000J (manufactured by Shimadzu Corporation), D ₅₀ was 6.1 [mu] m. The aqueous dispersion containing the droplets of the polymerizable monomer composition was put into a reactor equipped with a stirring blade,
The temperature was raised to ° C. to initiate the polymerization reaction. 80% polymerization conversion
, Sodium formaldehyde sulfoxylate (SFS) 5 as a redox initiator reducing agent
And an aqueous solution obtained by dissolving 0.5 parts of sodium ethylenediaminetetraacetate in 65 parts of distilled water was added to the reactor.
Next, after continuing the polymerization reaction for 8 hours, the reaction was stopped,
A pH 9.5 aqueous dispersion containing the produced colored polymer particles was obtained. The volume average particle diameter (dv) measured by taking out the colored polymer particles was 7.1 μm, and the volume average particle diameter (dv) / number average particle diameter (dp) was 1.31, rl /
rs was 1.14.

(E) Recovery of colored polymer particles While stirring the aqueous dispersion obtained in (d) above, sulfuric acid was added to adjust the pH of the aqueous dispersion to about 5.5, and acid washing was performed (at 25 ° C., 1 ° C.).
0 min). Next, filtration and dehydration were performed, and after dehydration, washing water was sprinkled to perform water washing. After the solid content was separated by filtration, the solid content was dried at 45 ° C. for two days and nights in a drier,
Colored polymer particles (polymerized toner) were collected.

(F) Preparation of developer 100 parts of the colored polymer particles obtained in the above (E) were treated with 0.8 part of hydrophobically treated silica having an average particle diameter of 12 nm (trade name “R202” manufactured by Degussa Co., Ltd.). Was added and mixed using a Henschel mixer to produce a non-magnetic one-component developer (hereinafter sometimes simply referred to as “toner”).

(G) Evaluation of Characteristics When the image was evaluated using the toner prepared in the above (f), the image was evaluated under high temperature and high humidity (H / H) and low temperature and low humidity (L / L).
In each of the cases below, a high-quality image with good color tone, high image density and no fog was obtained. The fluidity and preservability of the toner are good, and the fixing temperature is 130
° C and excellent fixability. The results are shown in Table 1.

[Example 2] In Example 1, a polymethacrylic acid ester macromonomer (trade name "AA6" manufactured by Toa Gosei Chemical Industry Co., Ltd., Tg
= 94 ° C.), and 0.3 parts of an oil-soluble polymerization initiator was used instead of 1,1,3,3-tetramethylbutyl peroxy neodecanoate (in place of t-butyl peroxy neodecanoate). Nippon Yushi Co., Ltd., product name "Perocta N"
D ") and the polymerization temperature is from 60 ° C to 55 ° C
Except having changed to, it carried out similarly to Example 1. When an image was evaluated using the obtained toner (a non-magnetic one-component developer), the toner under high temperature and high humidity (H / H) and low temperature and low humidity (L
(L) In any of the cases below, a high-quality image with good color tone, high image density and no fog was obtained. The fluidity and storability of the toner were very excellent, and the fixing temperature was as low as 130 ° C., and the fixing property was excellent. Table 1 shows the results
It was shown to.

Comparative Example 1 The procedure of Example 1 was repeated, except that the aqueous solution of the reducing agent for redox initiator was not added when the polymerization conversion reached 80%. . Obtained toner (non-magnetic one-component developer)
Had a fixing temperature of 120 ° C., but had poor fluidity and storage stability. Image evaluation was performed using this toner.
L) In any of the following cases, the image density was reduced and fogging occurred due to continuous printing. The results are shown in Table 1.

Comparative Example 2 In the preparation of the polymerizable monomer composition in Example 2, 83 parts of styrene and 17 parts of n-butyl acrylate were replaced by 80 parts of styrene and n-butyl acrylate. 20 parts of acrylate (calculated Tg = 5
5 ° C.), and when the polymerization conversion reached 80%, the same procedure as in Example 2 was carried out except that the aqueous solution of the reducing agent for redox initiator was not added. The obtained toner (non-magnetic one-component developer) has a fixing temperature of 120 ° C.
However, fluidity and storage stability were poor. When an image was evaluated using this toner, the image density was reduced and fogging was caused by continuous printing under both high temperature and high humidity (H / H) and low temperature and low humidity (L / L). The results are shown in Table 1.

[0102]

[Table 1]

(Footnotes) (1) The blending amounts are parts by weight. (2) Perbutyl ND: t-butyl peroxy neodecanoate (3) Perocta ND: 1,1,3,3-tetramethylbutyl peroxy neodecanoate (4) SFS: sodium formaldehyde sulfoxylate (5 ) Iron chelate: sodium ethylenediaminetetraacetate As is clear from the results in Table 1, in the production of the polymerized toner, after the polymerization using an oil-soluble polymerization initiator, the polymerization reaction is continued by adding a reducing agent for a redox initiator. By doing so, it is understood that a high quality toner having excellent fixing characteristics, fluidity, and storability, and having little environmental dependency can be obtained.

Example 3 (i) Preparation of Core Particles In Example 1, when preparing the polymerizable monomer composition,
Except that the monomer composition of 83 parts of styrene and 17 parts of n-butyl acrylate was changed to 78 parts of styrene and 22 parts of n-butyl acrylate (calculated Tg = 50 ° C.)
An aqueous dispersion containing colored polymer particles was obtained in the same manner as in Example 1. The polymerization conversion rate at the end of this step is almost 100
%Met. The colored polymer particles obtained in this step were used as core particles.

(Ii) Formation of Shell Using the colored polymer particles prepared in (i) above as core particles, a shell was formed thereon by the following method. 3 parts of methyl methacrylate (calculated Tg = 105 ° C.) and 100 parts of water were charged into an ultrasonic emulsifier and finely dispersed to prepare an aqueous dispersion of a polymerizable monomer for shell. To an aqueous dispersion containing the colored polymer particles (core particles) prepared in the above (i), an aqueous dispersion of a polymerizable monomer for shell and 1 part of ammonium persulfate as a water-soluble polymerization initiator are added,
After maintaining the polymerization temperature at 60 ° C. and continuing the reaction for 3 hours,
The reaction was stopped to obtain an aqueous dispersion containing colored polymer particles having a core-shell structure.

(Iii) Recovery of Colored Polymer Particles Having a Core / Shell Type Structure While stirring the aqueous dispersion containing the colored polymer particles having a core / shell type structure obtained in (ii) above, sulfuric acid was added. After the pH of the aqueous dispersion was adjusted to 4, acid washing (25 ° C., 10 minutes) was performed, and water was separated by filtration. Then, 500 parts of ion-exchanged water was added again to form a thriller, followed by washing with water. Thereafter, dehydration and water washing were repeated again. After the solid content was separated by filtration, the solid content was dried in a dryer at 45 ° C. for two days and nights to recover core-shell type colored polymer particles (polymerized toner).

(Iv) Preparation of Developer 100 parts of the colored polymer particles having a core-shell structure obtained in the above (iii) were subjected to hydrophobic treatment to silica having an average particle diameter of 14 nm (trade name: Nippon Aerosil Co., Ltd.) R202 ")
0.8 part was added and mixed using a Henschel mixer to produce a non-magnetic one-component developer (toner). The volume average particle size (dv) of the obtained toner was 7.2 μm.

(V) Evaluation of Characteristics Image evaluation was performed using the toner prepared in the above (iv).
L) In each of the cases below, a high-quality image with good color tone, high image density and no fog was obtained. The fluidity and preservability of the toner are good, and the fixing temperature is 12
The temperature was as low as 0 ° C., and the fixing property was excellent. The results are shown in Table 2.

Example 4 In the preparation of the polymerizable monomer composition in Example 2, 83 parts of styrene and 17 parts of n-butyl acrylate were replaced with styrene 7
8 parts and n-butyl acrylate 22 parts (calculated Tg = 50
° C) to obtain an aqueous dispersion containing colored polymer particles in the same manner as in Example 1. The polymerization conversion at the end of this step was almost 100%. In the same manner as in Example 3 except that the colored polymer particles obtained in this step were used as core particles, a colored polymer particle having a core-shell type structure (polymerized toner) and a non-magnetic one-component developer ( Toner). Image evaluation was performed using the obtained toner (non-magnetic one-component developer).
H) and under low temperature and low humidity (L / L),
A high-quality image with good color tone, high image density and no fog was obtained. The fluidity and storability of the toner were very excellent, and the fixing temperature was as low as 120 ° C., and the fixing property was excellent. The results are shown in Table 2.

Comparative Example 3 The procedure of Example 3 was repeated, except that the aqueous solution of the reducing agent for a redox initiator was not added when the polymerization conversion reached 80% in the production process of the core particles of Example 3. Was performed in the same manner as described above. The fixing temperature of the obtained toner (non-magnetic one-component developer) was 110 ° C.
The fluidity and storage stability were poor. When an image was evaluated using this toner, the image density was reduced and fogging was caused by continuous printing under both high temperature and high humidity (H / H) and low temperature and low humidity (L / L). The results are shown in Table 2.

Comparative Example 4 The procedure of Example 4 was repeated, except that the aqueous solution of the redox initiator reducing agent was not added when the polymerization conversion reached 80% in the production process of the core particles of Example 4. Was performed in the same manner as described above. The fixing temperature of the obtained toner (non-magnetic one-component developer) was 110 ° C.
The fluidity and storage stability were poor. When an image was evaluated using this toner, the image density was reduced and fogging was caused by continuous printing under both high temperature and high humidity (H / H) and low temperature and low humidity (L / L). The results are shown in Table 2.

[0112]

[Table 2]

(Footnotes) (1) The blending amounts are parts by weight. (2) Perbutyl ND: t-butyl peroxy neodecanoate (3) Perocta ND: 1,1,3,3-tetramethylbutyl peroxy neodecanoate (4) SFS: sodium formaldehyde sulfoxylate (5 ) Iron chelate: sodium ethylenediaminetetraacetate As is clear from the results in Table 2, in the production of the polymerized toner, after the polymerization using an oil-soluble polymerization initiator, the polymerization reaction is continued by adding a reducing agent for a redox initiator. By preparing core particles and forming a shell to form a core-shell structure, it is possible to obtain a high-quality toner with excellent fixing characteristics, fluidity, and storage stability, and low environmental dependency. I understand.

[0114]

According to the present invention, there is provided a method for producing a polymerized toner having a low fixing temperature, a uniform melting property, and excellent storage stability. Use of the polymerized toner of the present invention enables high-speed copying and printing, full color printing, and energy saving. Further, the polymerized toner of the present invention shows excellent transparency when printed and fixed on an OHP sheet. The polymerized toner of the present invention can form a high-quality image without fogging or a decrease in print density. According to the present invention,
An image forming method using a polymerized toner having such excellent characteristics and an image forming apparatus containing the polymerized toner are provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an image forming apparatus to which a polymerization toner of the present invention is applied.

[Explanation of symbols]

 1: photosensitive drum 2: charging roll 3: laser beam irradiation device 4: developing roll 5: blade (toner layer thickness regulating means) 6: toner supply roll 7: toner 8: stirring blade 9: casing (toner containing means) 10: transfer roll 11: transfer material 12: heating roll (fixing roll) 13: pressure roll

Claims (4)

[Claims] 1. A liquid obtained by suspending a polymerizable monomer composition containing at least a colorant, a polymerizable monomer, and a release agent in an aqueous dispersion medium containing a dispersion stabilizer. Dropping, (2) suspension polymerization of the polymerizable monomer composition in the presence of an oil-soluble polymerization initiator until the polymerization conversion falls within the range of 30 to 97%, and (3) When the polymerization conversion is within the above range, the production of a polymerized toner comprising a step of adding a reducing agent for a redox initiator to an aqueous dispersion medium, further continuing suspension polymerization, and generating colored polymer particles. Method. 2. The method according to claim 1, wherein in the step (1), a macromonomer is contained in the polymerizable monomer composition. 3. A liquid obtained by suspending a polymerizable monomer composition containing at least a colorant, a polymerizable monomer, and a release agent in an aqueous dispersion medium containing a dispersion stabilizer. (2) suspension polymerization of the polymerizable monomer composition in the presence of an oil-soluble polymerization initiator until the polymerization conversion falls within the range of 30 to 97%, (3) polymerization (4) a step of adding a reducing agent for a redox initiator to the aqueous dispersion medium when the conversion is within the above range, further continuing suspension polymerization, and producing colored polymer particles (a); A) polymerizable for a shell capable of forming a polymer having a glass transition temperature higher than the glass transition temperature of the polymer component constituting the colored polymer particles (a) in the presence of the colored polymer particles (a). The monomer is subjected to suspension polymerization, and the colored polymer particles (a) are used as core particles. A method for producing a polymerized toner having a core-shell structure, comprising the step of producing colored polymer particles (b) having a polymer layer formed thereon. 4. The method according to claim 3, wherein in the step (1), a macromonomer is contained in the polymerizable monomer composition.