JP2013061384A - Method of manufacturing toner particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing toner particles for manufacturing toner particles with a core-shell structure having a modified polyester resin shell obtained by molecularly bonding a polyester molecule and a styrene-acrylic copolymer molecule on a surface of a core particle.SOLUTION: A method of manufacturing toner particles includes the steps of: mixing a resin solution obtained by dissolving a styrene-acrylic modified polyester resin into an organic solvent and an aqueous medium to form a mixture liquid, and rotating the mixture liquid; applying a shear force to the rotated mixture liquid at a gap for passing the mixture liquid to form resin solution particles; and removing the organic solvent from the resin solution particles to form resin particles for a shell.

Description

  The present invention relates to a method for producing toner particles that constitute toner used for electrophotographic image formation, and more particularly, to a method for producing resin particles for shells used when producing toner particles having a core-shell structure.

  In an electrophotographic image forming method, a printed material is generally manufactured through the following steps. First, an electrostatic latent image is formed on the photosensitive member by irradiating the photosensitive member with exposure light, and the latent image is developed by supplying toner to the photosensitive member on which the electrostatic latent image is formed. Form. Next, the toner image on the photosensitive member is transferred to an image support such as paper, and the transferred toner image is heated and melted to fix the toner image to the image support to produce a printed matter. Then, the toner remaining on the photoconductor to which the toner image has been transferred is removed by a cleaning device, and the photoconductor from which the residual toner has been removed is charged, so that the next image can be formed.

  In recent years, so-called low-temperature fixing technology that fixes a toner image at a lower temperature than before has attracted attention in order to reduce power consumption and realize high-speed print production. In order to lower the fixing temperature of the toner, a resin that lowers the glass transition temperature and softening point of the binder resin constituting the toner and exhibits sharp melting and solidifying behavior with respect to the temperature is required. Toner design has been studied using such a resin having a low glass transition temperature and softening point, and it is possible to fix a toner image on a transfer material at a temperature lower than conventional ones (for example, Patent Document 1, 2).

  However, a toner compatible with low-temperature fixing produced using a binder resin having a low glass transition temperature and a softening point has a property that it is easily affected by thermal or mechanical stress. Specifically, when the toner is stored over time, depending on the environmental conditions, a phenomenon called blocking in which the toners adhere to each other occurs, and stable storage performance may not be obtained. In addition, when a large amount of prints are made and the printed material immediately after fixing is placed on the paper discharge tray or stored in a state where a large number of printed materials are stacked, the images or images may be affected by the influence of the temperature and the load of the stacked printed materials. This causes a phenomenon called tacking in which the paper and the white paper are bonded.

  As described above, the low-temperature fixing toner is required to have stable storage performance and stability that does not cause tacking even when subjected to thermal or mechanical stress during and after image formation. Therefore, a toner called a core-shell structure type in which a core particle surface made of a binder resin that melts at a low temperature is coated with a resin having a high glass transition temperature has been developed to enable both low-temperature fixability and heat-resistant storage stability (for example, And Patent Document 3). In addition, for example, techniques related to a method for producing a core-shell structure toner, such as a technique for producing composite fine particles for core particles by adding water to a mixture of a polyester resin, an ester wax, a colorant and an organic solvent to carry out transfer emulsification, are also studied. (For example, refer to Patent Document 4).

  The toner having the core-shell structure needs to reduce the thickness of the shell in order to stably develop the low-temperature fixing performance by the core particles. In this way, when the shell is thinned, the ratio of the shell resin to the toner particles decreases, and even if a resin having a high glass transition temperature is used as the shell resin, the low-temperature fixing performance by the core particles is hardly affected. It was considered.

  There is a polyester resin as one of the binder resins for toner. Since the polyester resin has a higher glass transition temperature and superior moldability compared to the styrene acrylic resin, if a thin shell is formed with the polyester resin, It was thought that a good core-shell toner could be obtained. Then, investigations have been made on a technique for producing a core-shell toner having a polyester resin shell on the surface of core particles containing a thermoplastic resin such as styrene acrylic resin (see, for example, Patent Document 5).

  However, it has been found that a toner having a core-shell structure in which a polyester resin shell is formed on the surface of the core particle containing styrene acrylic resin is difficult to develop a strong adhesive force between the shell and the core particle. It was. This is because the affinity between the polyester resin constituting the shell and the styrene acrylic resin constituting the core particle is low. The low affinity between the two is not only difficult to ensure the adhesion between the core and shell, but also the core particle. It has also been difficult to make the shell adhere to the surface evenly.

  In this way, even if a core-shell toner is made with a polyester resin shell and a core particle containing a styrene acrylic resin, the shell does not adhere uniformly and firmly to the core particle surface. The coated toner could not be made. Even if the surface of the core particle can be covered with a shell, the adhesion between the core and shell is weak, so the shell is easily peeled off by stress when stirred in the developing device, and it is extremely difficult to form a stable image. was. In the above-mentioned Patent Document 5, there is no description suggesting that the affinity between the core of the polyester resin and the core particle containing the styrene acrylic resin is improved, and a new technique for improving the affinity between the core and shell is studied. Had to do.

  Under such circumstances, a compound having a structure in which the condensation polymerization resin component and the addition polymerization resin component are molecularly bonded using a compound capable of reacting with both the condensation polymerization resin raw material monomer and the addition polymerization resin raw material monomer. A technique of using a resin for toner has been studied (for example, see Patent Document 6). A technique for forming a toner using a resin called modified polyester in which a radical polymer unit and a polyester unit are molecularly bonded via a divalent crosslinking group (for example, see Patent Document 7) has been studied. However, Patent Documents 6 and 7 do not describe the use of a modified polyester resin to produce a resin for forming a shell, and do not suggest the use of a modified polyester resin to improve the affinity between core shells. It was.

  The present inventor made a resin particle for shell formation with a modified polyester resin having a structure in which a polyester molecule and a styrene acrylic copolymer molecule are molecularly bonded, and this was adhered to a core particle containing a styrene acrylic resin to form a core-shell structure. We were considering making a toner. Here, in order to form a thin shell having a uniform thickness on the surface of the core particle, it was necessary to prepare resin fine particles having a particle diameter of about 100 nm, for example. Therefore, the present inventor dissolves a modified polyester resin having a structure in which a polyester molecule and a styrene acrylic copolymer molecule are molecularly bonded in an organic solvent to form a resin solution, and finely disperses the resin solution in an aqueous medium. It was considered to produce such shell resin particles.

  By the way, as a technique for forming fine particles by applying a mechanical action to a dispersion in which particles are dispersed in an aqueous medium, for example, inorganic particles are added and dispersed in an aqueous medium, and the inorganic particles collide under pressure. There is a technique for forming inorganic fine particles of 0.01 to 2 [mu] m by making (for example, see Patent Document 8).

JP 2001-42564 A JP 2004-163612 A JP 2005-221933 A JP 2007-57664 A JP 2005-338548 A JP 2010-128466 A JP 2011-28257 A Japanese Patent Laid-Open No. 11-57521

  However, Patent Document 8 does not disclose that fine particles are formed by dispersing and pressurizing liquid particles in an aqueous medium, and does not suggest that the resin solution is finely dispersed in the aqueous medium. . Also, since the resin solution has a high viscosity, it is necessary to give the resin solution a mechanical share such as a shearing force when forming the resin particles for the shell. In order to form uniform resin solution particles with uniform particle diameters Had to give a uniform share to the resin solution.

  One method of finely dispersing a resin solution added in an aqueous medium is a dispersion method using a bead mill method, but since the share due to the collision of beads is random and local, it is difficult to uniformly emulsify the resin solution. The particle size distribution of the shell resin particles became wider. As a result, the core cannot be uniformly formed on the surface of the core particles, and toner particles with exposed cores are formed. Such a core-shell toner easily adheres to each other during storage. When used for production, there was variation in charging performance. In this way, when forming the resin particles for the shell of the modified polyester resin by giving a mechanical share, there has been a demand for a dispersion treatment method for uniformly giving the share to the resin solution added in the aqueous medium. .

  The present invention provides a toner particle manufacturing method for producing a core-shell toner particle in which a uniform shell of a modified polyester resin in which a polyester molecule and a styrene acrylic copolymer molecule are molecularly bonded to each other is provided on the core particle surface. With the goal. That is, when forming a resin solution particle for a shell by giving a mechanical share to an aqueous medium containing the modified polyester resin solution, a dispersion treatment is performed to uniformly impart a mechanical share to the resin solution, The present invention provides a method for stably forming uniform resin solution particles.

The present inventor has found that the above-described problem can be solved by any of the configurations described below. That is, the invention described in claim 1
“At least on the surface of the core particles containing the resin and the colorant,
A method for producing toner particles comprising a step of forming a shell by adding resin particles containing a styrene acrylic modified polyester having a structure in which a styrene acrylic copolymer molecular chain is molecularly bonded to a polyester molecular chain,
The resin particles containing the styrene acrylic modified polyester are at least:
A resin solution obtained by dissolving a styrene acrylic modified polyester resin in an organic solvent and an aqueous medium are mixed to form a mixed solution,
Rotating the mixed liquid, and applying a shearing force to the mixed liquid in a gap through which the rotated mixed liquid passes, to form particles of the resin solution,
A method for producing toner particles, which is formed by removing an organic solvent from particles of the resin solution. ].

The invention described in claim 2
2. The method for producing toner particles according to claim 1, wherein the peripheral speed of the rotating means for rotating the mixed liquid is 10 m / sec or more and 20 m / sec or less. ].

The invention according to claim 3
“The gap through which the rotated mixed liquid passes is
Formed between a rotor for rotating the mixed liquid and a stator having a plurality of holes arranged concentrically around the rotor;
The shear force applied to the mixture is
The liquid flow generated when the liquid mixture is rotated by the rotor and the liquid flow generated when the liquid mixture is discharged from the hole of the stator, are generated. 3. A method for producing toner particles according to 1 or 2. ].

The invention according to claim 4
“Production of toner particles according to claim 1, wherein the resin solution has a content of the styrene acrylic modified polyester resin of 20% by mass or more and 60% by mass or less. Method. ].

The invention described in claim 5
The particle diameter of the resin solution particles in a state in which the particles of the resin solution are dispersed in the aqueous medium is a particle having a particle size of 50 nm or more and 250 nm or less. The manufacturing method of the toner particle of description. ].

The invention described in claim 6
“The resin contained in the core particles
6. The method for producing toner particles according to claim 1, wherein the toner particle contains at least a styrene acrylic copolymer. ].

The invention described in claim 7
[7] The method for producing toner particles according to any one of claims 1 to 6, wherein the styrene-acrylic modified polyester has a content of a styrene-acrylic copolymer of 5% by mass to 30% by mass. . ].

The invention according to claim 8 provides:
“The styrene-acrylic modified polyester is formed using an aliphatic unsaturated carboxylic acid represented by the following general formula (A),” according to any one of claims 1 to 7. Toner particle manufacturing method.

General formula (A): HOOC- (CR < ¹ > = CR _< ² _> ) _n- COOH
(Wherein R ¹ and R ² are a hydrogen atom, a methyl group or an ethyl group, and may be the same or different from each other. N is an integer of 1 or 2.) ” Is.

The invention according to claim 9 is:
“The styrene-acryl-modified polyester has the styrene-acrylic copolymer molecular chain molecularly bonded to an end of the polyester molecular chain. 9. A method for producing toner particles. ].

The invention according to claim 10 is:
“The styrene-acrylic modified polyester is one in which the styrene-acrylic copolymer molecular chain is formed by polymerizing a styrene monomer and an acrylate monomer in the presence of the polyester molecular chain. The method for producing toner particles according to claim 1, wherein: ].

  According to the present invention, it is possible to produce toner particles having a core-shell structure in which a shell of a modified polyester resin in which polyester molecules and styrene acrylic copolymer molecules are molecularly bonded to the surface of the core particles is uniformly formed.

  That is, an aqueous medium containing a resin solution in which a modified polyester resin is dissolved in an organic solvent is rotated using a rotating means, and by the action of shearing force generated when the rotated aqueous medium passes through the gap, It became possible to produce resin solution particles having a uniform particle diameter. In other words, by uniformly imparting a mechanical share of shear force to the resin solution that passes through the gap formed by the rotor and the stator having a plurality of holes provided around the rotor and is discharged from the holes. It is considered that resin solution particles having a uniform particle diameter are formed.

  As a result, toner particles having a core-shell structure in which the core particles are not exposed can be obtained, the toner particles do not adhere to each other during storage, and a stable printed image with excellent image quality is obtained due to good chargeability. It became possible to do. In addition, it has become possible to provide a core-shell toner with excellent durability that does not show deterioration due to breakage of a modified polyester molecular chain due to stress, etc., while giving mechanical shares to form resin particles for shells. .

It is the schematic of the rotor / stator type distributed processing apparatus which can be used for shell formation by this invention. 3 is a cross-sectional view of toner particles having a core-shell structure formed in the present invention. FIG.

  The present invention relates to a method for producing toner particles having a core-shell structure used for electrophotographic image formation. The method for producing toner particles according to the present invention contains at least a styrene acrylic modified polyester having a structure in which a styrene acrylic copolymer molecular chain is molecularly bonded to a polyester molecular chain on the surface of a core particle containing a resin and a colorant. Resin particles are added to form a shell.

  In the present invention, toner particles having a core-shell structure are prepared by coating a shell containing a modified polyester resin in which a styrene-acrylic copolymer molecular chain is covalently bonded to a polyester molecular chain on the surface of the core particle. As will be described later, the core-shell toner particles are formed by fusing and coating the core particle surfaces with shell-forming resin particles, and the shell-forming resin particles uniformly coat the core particle surfaces without unevenness. Therefore, it has been necessary to make the particle size around 100 nm, for example, and to make the particle size uniform with no variation.

  In addition, when forming resin particles for shell formation using a styrene acrylic modified polyester resin that is a polymer, a resin solution is formed by dissolving the resin in an organic solvent and dispersing the resin solution in an aqueous medium. The particles had to be made.

  Here, when a particle having a size of, for example, about 100 nm is produced by a conventional dispersion method such as a bead mill method, a certain amount of shearing force is imparted to the resin solution particles by the collision of the beads. Solution particles can be formed. However, since the shear caused by the collision of the beads is random, the dispersion and emulsification of the resin solution is not uniformly performed, and there is a problem that the particle size distribution of the formed resin particles for the shell is widened. As a result, it was considered that the shell could not be uniformly coated on the surface of the core particles, and good heat-resistant storage property and toner chargeability could not be obtained sufficiently.

  The present inventor examined a method for producing resin particles having a uniform particle diameter by uniformly dispersing and emulsifying a resin solution when forming resin particles for a shell with a styrene acrylic modified polyester resin. Then, by using a dispersion processing device called “rotor / stator” system as a means for performing dispersion emulsification of the resin solution, resin solution particles having a uniform particle size are formed, and the shell is uniformly distributed on the surface of the core particles. The production of modified polyester resin particles to be formed in the following manner.

  In the present invention, the shear force applied to the resin solution is not randomly applied locally as in the bead mill method, but the shear force is uniformly and regularly applied to a whole amount of the resin solution existing in the gap. In addition, the dispersion emulsification of the resin solution can be performed uniformly without unevenness. A resin solution is continuously supplied into the gap. Therefore, it is possible to stably produce toner particles having a core-shell structure in which styrene-acrylic modified polyester resin particles having a uniform particle diameter are stably formed, and a shell is uniformly formed on the surface of the core particles without unevenness.

  In the present invention, since a shearing force can be uniformly applied to the resin solution, unlike the case of forming particles by locally applying a strong shearing force like the bead mill method, the stress can be reduced. It is considered that the dispersion and emulsification of the resin solution can be performed under the condition. Therefore, it is considered that the molecular chain constituting the styrene acrylic modified polyester resin is not cut by the stress caused by the shearing force and contributes to the improvement of the durability of the toner.

  Hereinafter, the present invention will be described in detail.

  As described above, the present invention is to produce shell-forming resin particles using a styrene-acrylic modified polyester having a structure in which a styrene-acrylic copolymer molecular chain is molecularly bonded to a polyester molecular chain. And, the resin particles are “at least a resin solution in which a styrene acrylic modified polyester resin is dissolved in an organic solvent and an aqueous medium are mixed to form a mixed solution, and the formed mixed solution is rotated, and the rotated mixed solution It is formed by applying a shearing force to the mixed solution in a gap through which the resin solution passes to form resin solution particles, and removing the organic solvent from the formed resin solution particles.

Specifically, it is produced through the following steps. That is,
(1) A step of forming a resin solution by dissolving a styrene acrylic modified polyester resin in an organic solvent (2) An aqueous medium containing the resin solution is formed by adding the resin solution to the aqueous medium, and the formed aqueous medium is A step of forming a resin solution particle by applying a shearing force in a gap through which the rotated aqueous medium passes, and a step of removing an organic solvent from the resin solution particles dispersed in the aqueous medium. The above steps will be described in detail.

(1) Step of dissolving a styrene acrylic modified polyester resin in an organic solvent to form a resin solution In this step, a resin solution is prepared by dissolving a styrene acrylic modified polyester resin in a known organic solvent such as ethyl acetate. In the present invention, a “resin solution in which a styrene acrylic modified polyester resin is dissolved in an organic solvent” is prepared.

  In the present invention, the content of the styrene acrylic-modified polyester resin when forming the resin solution is not particularly limited, but is preferably 20% by mass or more and 60% by mass or less, for example. That is, the ratio of the resin and the solvent when forming the styrene acrylic modified polyester resin solution is preferably 20/80 to 60/40 in terms of resin / solvent (mass ratio). By setting the ratio of the organic solvent in the above range, it is preferable because an appropriate viscosity is imparted to the resin solution and colloidal particles of the resin solution having a uniform particle size can be easily formed in the next step.

  The organic solvent that dissolves the resin in this step is preferably a water-insoluble one that dissolves the styrene acrylic modified polyester resin and can form oil droplets (resin solution particles) in an aqueous medium. When the resin particles are formed with a low boiling point which is easy to be removed by distillation. Specific examples of the organic solvent include, for example, ethyl acetate, methyl ethyl ketone, diethyl ether, etc. Among them, ethyl acetate is preferable.

  In addition, when the styrene acrylic modified polyester resin solution is dispersed in the aqueous medium in the next step, the resin solution particles can be stabilized by using a carboxy group present in the polyester segment as a hydrophilic group. As a means for realizing this, there is a method of using a strong alkali typified by an aqueous sodium hydroxide solution in addition to an organic solvent when forming a resin solution. That is, by adding a strong alkali, a carboxy group present in the polyester segment is dissociated to act as a hydrophilic group, and a colloidal stability function is imparted. The amount of strong alkali added is preferably in the range of 70 mol% to 130 mol% with respect to 100 mol% of the carboxy group of the polyester segment, for example.

  Thus, when forming the styrene acrylic modified polyester resin solution, an appropriate viscosity is imparted to the resin solution depending on the amount of the organic solvent added, and it becomes easy to form fine resin solution particles. Further, by using a strong alkali typified by an aqueous sodium hydroxide solution together, the carboxy group present in the polyester segment is dissociated to act as a hydrophilic group, and a stable resin solution particle can be formed with respect to an aqueous medium. .

(2) A resin solution is charged into an aqueous medium to form an aqueous medium containing the resin solution, the formed aqueous medium is rotated, and a shearing force is applied in a gap through which the rotated aqueous medium is passed to give the resin. Step of forming solution particles In this step, the resin solution formed in the step (1) is put into an aqueous medium, the aqueous medium containing the resin solution is pressurized, and a shearing force is applied to the pressurized resin solution. By adding, a resin solution particle dispersion in which resin solution particles are dispersed in an aqueous medium is prepared. This process includes the steps of “mixing a resin solution in which a styrene acrylic modified polyester resin is dissolved in an organic solvent and an aqueous medium to form a mixed solution” and “rotating the mixed solution and rotating the mixed solution” The resin solution particles are formed by applying a shearing force to the mixed solution in the gap through which the resin passes.

  In this step, “rotor / stator method” is used to “rotate the aqueous medium containing the resin solution and apply a shearing force to the aqueous medium containing the rotated resin solution to produce a resin solution particle dispersion”. A dispersion of resin solution particles is produced by the method called Hereinafter, a method for producing a resin solution particle dispersion using a “rotor / stator dispersion treatment apparatus” will be described.

  In the present invention, a dispersion treatment method called “roller / stator method” is used when producing resin particles containing a styrene acrylic modified polyester used for forming a shell. The “roller / stator type dispersion processing apparatus” has the structure shown in FIG. 1, and includes at least a flow path 11 through which an aqueous medium containing a resin solution passes, a rotor (rotor) 12 that rotates the aqueous medium, A stator (stator) 14 having a plurality of holes arranged concentrically around the rotor 12 is provided, and a gap 13 is formed between the rotor 12 and the stator 14.

  FIG. 1A is a front view of a roller / stator type distributed processing apparatus 10, and FIG. 1B is a view of FIG. 1A viewed from the direction of the arrow (↑) shown in the figure. Here, the channel 11 refers to a space through which an aqueous medium containing a resin solution can pass, and the holes provided in the gap 13 and the stator 14 also constitute a part of the channel 11. In FIG. 1, a white arrow indicating the moving direction of the aqueous medium is used.

  The rotor 12 is rotated by a motor (not shown) through a shaft 12a. The gap 13 formed between the rotor 12 and the stator 14 has a width of about 0.5 mm. When the width is narrowed, a large shearing force is obtained. However, the rotor 12 is rotated at a high speed to disperse the resin solution particles. From the viewpoint of stably forming the liquid, it is preferable not to make it too narrow. The shearing force generated in the gap 13 is preferably controlled, for example, by controlling the peripheral speed of the rotor, as will be described later.

  The dispersion processing apparatus 10 of FIG. 1 forms resin solution particles having a uniform particle size according to the following procedure. First, an aqueous medium (mixed liquid referred to in the present invention) containing a resin solution supplied to the dispersion treatment apparatus 10 reaches the rotor 12 via the flow path 11. Here, the aqueous medium containing the resin solution may be stirred in advance, and the aqueous medium in which the resin solution is made into particles of a certain size may be supplied. As described above, it is preferable to use a water-based medium containing resin solution particles of a certain size by stirring the mixed solution supplied to the dispersion treatment apparatus 10 in advance in order to efficiently form fine resin solution particles. .

  Next, the aqueous medium reaches the gap 13 formed between the rotor 12 and the stator 14 by the action of centrifugal force generated by the rotation of the rotor 12. In the gap 13, a shearing force is generated by the action of a liquid flow generated by high-speed rotation of the rotor 12, a collision with the stator 14, a liquid flow generated when passing through the hole of the stator 14, and the like. The resin solution in the aqueous medium becomes particles by the action of the shearing force, and a dispersion of resin solution particles is formed.

  The gap 13 is formed between a rotor 12 that rotates an aqueous medium containing a resin solution and a stator 14 that is disposed concentrically around the rotor 12. Further, the shearing force generated in the gap 13 is generated by a liquid flow generated by the rotation of the rotor 12 or a liquid flow generated when the aqueous medium is discharged from the hole of the stator 14.

  Formation of the resin solution particles by the rotor / stator type dispersion treatment apparatus 10 shown in FIG. 1 is performed in the following manner. That is, in the dispersion processing apparatus 10, the rotor 12 is rotated in a state where the minute gap 13 exists between the rotor 12 and the stator 14, and the rotation of the rotor causes the aqueous medium containing the resin solution to be rotated. Kinetic energy is given. The aqueous medium to which kinetic energy is applied from the rotor 12 rotating at high speed increases in speed by passing through the narrow gap 13, and the aqueous medium having increased speed intermittently causes the jet flow in the flow path 11. It is considered that a liquid-liquid shearing force is generated at the velocity interface.

  In the gap 13, fine resin solution particles are formed by the action of the shearing force generated when the aqueous medium passes through the gap 13, and the aqueous medium further has holes formed in the stator 14. It is considered that the speed is further increased by passing. Then, due to the aqueous medium passing through the holes of the stator 14, a higher-speed jet flow is intermittently formed in the flow path 11, and a stronger liquid generated at the velocity interface of the intermittent jet flow − It is considered that resin particles having a particle diameter that enables uniform shell formation without unevenness are formed by the action of the liquid shear force. The rotor / stator type distributed processing apparatus that can be used in the present invention is not particularly limited, and examples thereof include “CLEARMIX CLM-0.8S” (manufactured by M Technique Co., Ltd.). .

  The particle diameter of the resin solution particles formed by the rotor / stator type dispersion treatment apparatus 10 shown in FIG. 1 can be controlled by a known method. As a typical control method, the peripheral speed of the rotor 12 is used. The method etc. which control are mentioned. That is, as the peripheral speed of the rotor 12 increases, it becomes possible to generate a large shearing force, which is preferable for forming small-diameter resin solution particles. Although the circumferential speed of the rotor 12 is not specifically limited, For example, 10 m / s or more and 20 m / s or less are preferable. By setting the peripheral speed of the rotor 12 within the above range, a resin having a particle diameter of 50 nm or more and 250 nm or less, which is optimal for forming a uniform shell with no unevenness on the core particle surface, as described in Examples below. Solution particles can be produced stably.

  Further, in the rotor / stator type dispersion processing apparatus 10, by performing continuous dispersion processing for 30 minutes to 75 minutes at a peripheral speed in the above range with respect to 1 kg of the mixed solution, as shown in the examples described later, It is possible to form resin solution particles having a volume average particle size of 50 nm or more and 250 nm or less.

  In this step, the resin solution formed in the step (1) is added to the aqueous medium. The “aqueous medium” here contains at least 85% by mass or more of water. It is a liquid. Specifically, it is composed of water and an organic solvent soluble in water in addition to an aqueous solution in which a known surfactant typified by sodium lauryl sulfate is dissolved in water. An aqueous solution is available.

(3) The step of removing the organic solvent from the resin solution particles dispersed in the aqueous medium In this step, the organic solvent is removed from the resin solution particles formed in the step (2) by a known method, The resin particles for the shell are formed and correspond to “removing the organic solvent from the resin solution particles” in the present invention.

  As a specific method for removing the organic solvent, for example, a vacuum distillation method that promotes evaporation of the organic solvent by heating an aqueous medium in which resin solution particles are dispersed and placing the aqueous medium in a pressure state lower than atmospheric pressure. Etc. are mentioned as a preferable method.

  As described above, by adopting the procedure of (1) to (3) above, a resin solution particle for a shell containing the styrene acrylic modified polyester is prepared using a rotor / stator type dispersion treatment device, Furthermore, resin particles for shells can be produced.

  Next, the structure of the toner produced in the present invention will be described. In the present invention, a toner having a structure called a core-shell toner is produced. Here, the core-shell toner is a toner particle having a resin region (shell) having a relatively high glass transition temperature on the surface of a resin particle (core particle) having a relatively low glass transition temperature containing a colorant or wax. It is. An example of the structure of the core-shell toner is shown in FIG. Each toner (toner particle) T shown in FIG. 2 has a core particle A made of a resin 2 containing a colorant 1 and a shell B formed by coating the resin 3 on the surface of the core particle A. The shell B has a structure in which the surface of the core particle A is coated.

  The cross-sectional structure of the core-shell toner can be confirmed using known means such as a transmission electron microscope (TEM) or a scanning probe microscope (SPM). Here, a method for observing the cross-sectional structure of the toner with a transmission electron microscope (TEM) will be described. As for the cross-sectional structure of the toner, the cross-sectional structure of the toner is observed with a transmission electron microscope, for example, in the following procedure.

  First, after sufficiently dispersing the toner in a room temperature curable epoxy resin, embedding and dispersing in a fine styrene powder having a particle size of about 100 nm, and then performing pressure molding to form a block containing the toner. Make it. Next, if necessary, the prepared block is dyed with ruthenium tetroxide or osmium tetroxide if necessary, and then cut into a thin piece of 80 to 200 nm in thickness with a microtome equipped with diamond teeth. A measurement sample is prepared.

  Next, the flaky sample for measurement is set in a transmission electron microscope (TEM), and the cross-sectional structure of the toner is photographed. The magnification of the electron microscope is preferably such that the cross section of one toner particle enters the field of view, specifically about 10,000 times. Further, the number of toner particles for taking a photograph is preferably 10 or more.

  Observation of the cross-sectional structure of the toner with a transmission electron microscope can be sufficiently handled by a model that is generally well known among those skilled in the art. For example, “LEM-2000 type (manufactured by Topcon)” And “JEM-2000FX (manufactured by JEOL Ltd.)”.

  It is also possible to calculate the shell coverage on the core surface by electron microscope observation. That is, it is possible to calculate the image information captured by a transmission electron microscope (TEM) by, for example, processing with a commercially available image processing apparatus “Luzex F” (manufactured by Nireco), and the core area of the captured toner It is calculated from the area of the shell region. The average coverage of the shell is determined by using a cross-sectional structure photograph of at least 10 toners.

  Next, the shell constituting the core shell toner produced in the present invention will be described. The shell constituting the toner produced in the present invention contains a resin called styrene acrylic modified polyester in which a styrene acrylic copolymer molecular chain is molecularly bonded to a polyester molecular chain. The molecular structure of the styrene acrylic modified polyester is composed of a polyester segment and a styrene acrylic copolymer segment, and the polyester segment and the styrene acrylic copolymer segment are molecularly bonded.

  In the toner produced in the present invention, a shell is formed of a styrene acrylic modified polyester resin having a structure in which a styrene acrylic copolymer molecular chain is molecularly bonded to a polyester molecular chain, so that the shell is uniformly distributed on the surface of the core particles. It can be attached. That is, due to the presence of the styrene acrylic copolymer molecular chain bonded to the polyester molecular chain, the shell resin exhibits an affinity for the core particle containing the styrene acrylic copolymer, so that the shell resin It adheres to any part of the surface of the core particle with the same probability. As a result, the shell resin can adhere to the surface of the core particle with a uniform thickness without unevenness of the shell. The core-shell toner in which the core particle surface is uniformly coated with a shell uniformly enables both low-temperature fixability and heat-resistant storage stability.

  In addition, it is considered that the presence of styrene acrylic copolymer molecules in the shell resin allows the shell resin particles to exhibit appropriate dispersibility during shell formation and form a thin uniform shell on the surface of the core particles. That is, the presence of the styrene acrylic copolymer molecule reduces the affinity between the polyester molecular chains, avoids aggregation of the resin particles for the shell, and creates an environment where the particles adhere to the core particle surface at a distance from each other. It is considered a thing.

  In the core-shell toner produced in the present invention, the shell resin expresses affinity for the core particles, expresses dispersibility between the shell resins, and uniformly adheres the shell to the surface of the core particles. It enables both low-temperature fixability and heat-resistant storage stability.

  The content ratio of the shell resin in the binder resin constituting the core-shell toner produced in the present invention is preferably 5% by mass to 50% by mass, and more preferably 10% by mass to 40% by mass with respect to the total amount of the binder resin. . When the content ratio of the shell resin is within the above range, an amount of the shell resin that covers the entire surface of the core particles is supplied, which is preferable for forming a toner that achieves both heat storage stability and low-temperature fixability. It is.

  Next, the styrene acrylic modified polyester used for the shell resin will be described. Here, the “styrene acrylic modified polyester” is a polyester molecule having a structure in which a styrene acrylic copolymer molecular chain (also referred to as a styrene acrylic copolymer segment) is molecularly bonded to a polyester molecular chain (also referred to as a polyester segment). It is. The styrene acrylic modified polyester used in the present invention has a molecular structure in which a styrene acrylic copolymer molecular chain is bonded to a polyester molecular chain, and a copolymer having a styrene acrylic copolymer segment covalently bonded to a polyester segment. It is a coalescence.

  The styrene acrylic modified polyester used in the present invention is not particularly limited as long as it has a molecular structure in which a styrene acrylic copolymer molecular chain is bonded to a polyester molecular chain. Among them, the styrene-acrylic copolymer segment content is preferably 5% by mass or more and 30% by mass or less. Here, the content ratio of the styrene acrylic copolymer segment in the styrene acrylic modified polyester molecule is also called “styrene acrylic modified amount”, and the ratio (mass ratio) of the styrene acrylic copolymer segment in the styrene acrylic modified polyester molecule. It is. Specifically, it means the ratio of the polymerizable monomer mass used for forming the styrene acrylic copolymer to the total mass of polymerizable monomers used when synthesizing the styrene acrylic modified polyester resin.

  By setting the “styrene acrylic modification amount” within the above range, the above-described shell can be more reliably formed. That is, the affinity between the styrene-acrylic modified polyester resin and the core particles is moderately controlled, and it becomes easy to form a uniform and thin shell. As a result, a core-shell toner that achieves both low-temperature fixability and heat-resistant storage stability can be obtained. It can be produced more stably.

  The styrene acrylic modified polyester used in the present invention is not particularly limited as long as the molecular structure has two types of homopolymer segments, a polyester segment and a styrene acrylic copolymer segment. Specifically, a block copolymer structure in which a styrene acrylic copolymer segment is bonded to the end of a polyester segment, or a graft copolymer structure in which a branched structure of a styrene acrylic copolymer segment is formed on a polyester segment. Is mentioned.

  Among them, the block copolymer structure in which the styrene acrylic copolymer molecular chain is bonded to the end of the polyester molecular chain easily forms a shell having a phase separation structure in which the polyester phase and the styrene acrylic copolymer phase are independent, This is preferable in forming a function-separated shell. That is, the heat resistance imparting performance by the high glass transition temperature and softening point temperature by the polyester phase and the improvement of the adhesive strength between the core particles by the styrene acrylic copolymer phase can be efficiently expressed.

  The content ratio of the styrene acrylic modified polyester in the shell resin is preferably 70% by mass to 100% by mass and more preferably 90% by mass to 100% by mass with respect to 100% by mass of the shell resin. By setting the content ratio of the styrene acrylic modified polyester in the resin for the shell within the above range, it is easy to ensure the affinity between the core particles and the shell, sufficient heat storage stability is obtained, and charging and crush resistance are improved. Effect is also obtained.

  The method for forming the styrene acrylic modified polyester used in the present invention is not particularly limited as long as it can form a polymer having a structure in which a polyester segment and a styrene acrylic copolymer segment are molecularly bonded. It is not something. Specific examples of the method for forming the styrene acrylic modified polyester include the following methods.

(1) A method in which a polyester segment is formed in advance and a styrene acrylic modified polyester is formed by performing a polymerization reaction to form a styrene acrylic copolymer segment in the presence of the polyester segment. Polymerization is carried out by condensation reaction of acid and polyhydric alcohol to form a polyester segment. Next, in the presence of the polyester segment, a vinyl monomer such as a styrene monomer or an acrylate monomer is polymerized to form a styrene acrylic copolymer segment. At this time, in addition to the styrene monomer and the acrylate monomer, a site capable of reacting with the carboxy group (—COOH) or hydroxy group (—OH) remaining in the polyester segment, and the vinyl monomer A compound having a reactive site is also used. That is, when this compound reacts with a carboxy group (—COOH) or a hydroxy group (—OH) in the polyester segment, the polyester segment has a structure in which the compound is bonded. And a styrene acrylic copolymer segment is formed by carrying out addition reaction, such as radical polymerization, of a styrene-type monomer and an acrylate-type monomer in presence of the polyester segment which combined the said compound. At this time, a styrene acrylic modified polyester having a structure in which the polyester segment and the styrene acrylic copolymer segment are molecularly bonded can be formed through a site capable of reacting with the vinyl monomer of the compound bonded to the polyester segment. it can.

  That is, the method (1) is a method of “forming a styrene acrylic copolymer molecular chain by polymerizing at least a styrene monomer and an acrylate monomer in the presence of a polyester molecular chain”. Applicable. The method (1) includes a method in which the styrene monomer and the acrylate monomer are added to the reaction system before the styrene monomer and the acrylate monomer are added to the reaction system. There is a method in which a monomer is added together to react. The method (1) is a method preferably used for forming a styrene acrylic modified polyester having a block copolymer structure in which a styrene acrylic copolymer molecular chain is molecularly bonded to the end of a polyester molecular chain, as will be described later. It is.

(2) A method of polymerizing a styrene acrylic copolymer segment in advance and performing a polymerization reaction to form a polyester segment in the presence of the styrene acrylic copolymer segment to form a styrene acrylic modified polyester. Then, a styrene-acrylic copolymer segment is formed by addition reaction of a styrene-based monomer and a vinyl-based monomer typified by an acrylate-based monomer. Next, in the presence of the styrene acrylic copolymer segment, a polyvalent carboxylic acid and a polyhydric alcohol are polymerized to form a polyester segment. At this time, in addition to the polyvalent carboxylic acid and the polyhydric alcohol, a compound having a site capable of reacting with the styrene acrylic copolymer segment and a site capable of reacting with the polyvalent carboxylic acid or polyhydric alcohol is also used. That is, by reacting this compound with the styrene acrylic copolymer segment, the styrene acrylic copolymer segment has a structure in which the compound is bonded. And a polyester segment is formed by carrying out the condensation reaction of polyhydric carboxylic acid and a polyhydric alcohol in presence of the styrene acrylic copolymer segment which combined the said compound. At this time, a styrene acrylic modified polyester having a structure in which the styrene acrylic copolymer segment and the polyester segment are molecularly bonded is formed through a site capable of reacting with the carboxylic acid or alcohol of the compound bonded to the styrene acrylic copolymer segment. be able to.

(3) A method in which a polyester segment and a styrene acrylic copolymer segment are respectively formed and bonded to form a styrene acrylic modified polyester. In this method, first, a polyvalent carboxylic acid and a polyhydric alcohol are subjected to a condensation reaction. To form a polyester segment. In addition to the reaction system for forming the polyester segment, a styrene-acrylic copolymer segment is formed by addition polymerization of a styrene monomer and an acrylate monomer. Next, a system in which the polyester segment and the styrene acrylic copolymer segment coexist is formed, and a compound having a portion that can be bonded to the polyester segment and a portion that can be bonded to the styrene acrylic copolymer segment is added thereto. And the styrene acrylic modified polyester of the structure where the polyester segment and the styrene acrylic copolymer segment were molecularly bonded can be formed through the compound.

  Among the forming methods (1) to (3), the method (1) is easy to form a styrene acrylic modified polyester having a structure in which a styrene acrylic copolymer molecular chain is bonded to the end of a polyester molecular chain and a production process. Can be simplified. In the method (1), since the polyester segment is formed in advance and then the compound is introduced and bonded to the polyester segment, the compound has a very high probability of binding to the end of the polyester segment. Therefore, it is preferable because a styrene acrylic modified polyester having a structure defined in the present invention can be reliably formed.

  In the forming methods (1) to (3), it is preferable to perform heat treatment for uniformly mixing a compound such as a polymerizable monomer used for forming the styrene acrylic modified polyester. Specifically, the temperature is preferably 80 ° C to 120 ° C, more preferably 85 ° C to 115 ° C, and particularly preferably 90 ° C to 110 ° C. Heating under the above temperature range facilitates mixing of polyester molecular chains, styrene monomers, acrylate monomers, and the like, which is preferable for forming a styrene acrylic modified polyester.

  The polyester segment constituting the styrene acrylic modified polyester used in the present invention preferably has a glass transition temperature of 40 ° C to 70 ° C, more preferably 50 ° C to 65 ° C when it is a single polyester molecular chain. . When the glass transition temperature is 40 ° C. or higher, it is possible to form a toner image in which the polyester segments are appropriately aggregated during fixing and the hot offset phenomenon does not occur. In addition, since the glass transition temperature is 70 ° C. or lower, a low-temperature fixing toner that melts a toner image at a lower temperature than before can be produced without inhibiting the melting of the styrene-acrylic copolymer resin during fixing. This is preferable.

  The polyester segment constituting the styrene acrylic modified polyester preferably has a weight average molecular weight (Mw) of 1,500 or more and 60,000 or less, and 3,000 or more and 40,000 or less when it is a single polyester molecular chain. Those are more preferred. By setting the weight average molecular weight to 1,500 or more, an appropriate cohesive force can be imparted to the entire toner resin, and a toner image that does not cause a hot offset phenomenon during fixing can be formed. Further, when the weight average molecular weight is 60,000 or less, sufficient melting can be achieved by heating in a short time, and a firm fixed image can be formed by cooling. Therefore, it is preferable in forming a toner image by low-temperature fixing.

  The styrene acrylic copolymer segment constituting the styrene acrylic modified polyester used in the present invention has a glass transition temperature (Tg) at the time of a single styrene acrylic copolymer molecular chain, which is 35 ° C. or higher as in the case of the core particles described later. The thing of 60 degrees C or less is preferable, and the thing of 30 degrees C or more and 50 degrees C or less is more preferable. The styrene acrylic copolymer segment preferably has a weight average molecular weight (Mw) of 2,000 to 100,000 as in the case of the core particles described later when it is a single styrene acrylic copolymer molecular chain.

  When the styrene acrylic modified polyester is formed by the forming methods (1) to (3), a compound for molecularly bonding the polyester segment and the styrene acrylic copolymer segment is used. This compound is a compound having a site capable of reacting with a carboxy group (—COOH) or a hydroxy group (—OH) remaining in a polyester segment and a site capable of reacting with a vinyl monomer. Is applicable. In addition, in the formation method of the above (2), “in addition to the polyvalent carboxylic acid and the polyhydric alcohol, it has a site capable of reacting with the styrene acrylic copolymer segment and a site capable of reacting with the polycarboxylic acid or polyhydric alcohol. The “compound” is applicable. Furthermore, the formation method (3) corresponds to “a compound having a site capable of binding to a polyester segment and a site capable of binding to a styrene acrylic copolymer segment”.

  This compound includes a functional group capable of performing a condensation reaction with a carboxy group (—COOH) or a hydroxy group (—OH) remaining in a polyester segment, a carbon-carbon double bond capable of performing an addition reaction with a styrene acrylic copolymer segment, and the like. Having an unsaturated structure of Specific examples of such compounds include vinyl compounds having a carboxy group such as acrylic acid, methacrylic acid, fumaric acid and maleic acid, and vinyl carboxylic anhydrides such as maleic anhydride.

  The amount of the compound used for molecularly bonding the polyester segment and the styrene acrylic copolymer segment is 0.1% by mass or more and 5.0% by mass when the total of the compounds used for forming the styrene acrylic modified polyester is 100% by mass. The following is preferable, and 0.5% by mass or more and 3.0% by mass or less is more preferable. Here, the compound used for forming the styrene acrylic modified polyester is a polyester segment, a styrene monomer, an acrylate monomer, and a compound that molecularly bonds the polyester segment and the styrene acrylic copolymer segment.

  Further, the amount of the styrene monomer and the acrylate monomer used in forming the styrene acrylic modified polyester used in the present invention is 5% by mass or more in total when the above-mentioned total is 100% by mass. The content is preferably 30% by mass or less. That is, it corresponds to the ratio (mass ratio) of the styrene acrylic copolymer segment in the styrene acrylic modified polyester molecules described above.

  The polyester segment constituting the styrene acrylic modified polyester used in the present invention is formed by subjecting a known polycarboxylic acid and polyhydric alcohol to a polycondensation reaction in the presence of a catalyst. The polyester segment can be a derivative of the aforementioned polyvalent carboxylic acid or polyhydric alcohol used as a raw material. The polyvalent carboxylic acid derivative includes an alkyl ester, an acid anhydride, or an acid chloride of the polyvalent carboxylic acid. Etc. Polyhydric alcohol derivatives include polyhydric alcohol ester compounds and hydroxycarboxylic acids.

Hereinafter, specific examples of polyvalent carboxylic acid and polyhydric alcohol that can be used for forming the polyester segment will be described. First, examples of the polyvalent carboxylic acid include known divalent carboxylic acids and trivalent or higher carboxylic acids called aliphatic dicarboxylic acids and aromatic dicarboxylic acids. Specific examples of the divalent carboxylic acid include, for example,
Oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid fumaric acid, citraconic acid, diglycolic acid, cyclohexane -3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, malonic acid, pimelic acid, tartaric acid phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, hexahydroterephthalate Acids p-Carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid, diphenylacetic acid diphenyl-p, p'-dicarboxylic acid, naphthalene-1, 4-dicarboxylic acid, naphthalene 1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, dodecenyl succinic acid and the like.

Specific examples of trivalent or higher carboxylic acids include, for example,
Examples include trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid.

  Among the polyvalent carboxylic acids, by forming a polyester segment using an aliphatic unsaturated dicarboxylic acid having a carbon-carbon unsaturated bond in the molecular structure such as fumaric acid, maleic acid, and mesaconic acid, the following Since it is thought that such an effect is show | played, it is preferable.

  In other words, when forming a shell, a thin shell with a uniform thickness and a smooth surface can be more reliably formed, so that a toner having both heat-resistant storage properties and low-temperature fixability can be more reliably obtained. Can be produced. This is presumably because the presence of a carbon-carbon unsaturated bond in the polyester molecule forms an environment in which the polyester resin particles easily adhere to the surface of the core particles containing the styrene acrylic resin.

  This is because the polyester resin generally has a hydrophobic property, and therefore, when the toner particles are produced by the emulsion association method described later, the polyester resin particles aggregate in an aqueous medium in which the core particles are present, and the polyester resin particles move to the surface of the core particles. Can hardly adhere. However, the presence of a carbon-carbon unsaturated bond in the polyester molecule imparts hydrophilicity to the polyester resin due to the polar action between the unsaturated bonds, avoiding aggregation of the polyester resin particles, and the surface of the core particles. It is thought that it becomes possible to adhere to. Further, by imparting hydrophilicity to the polyester resin, it becomes easy to adopt a form in which the polyester molecular chains are easily oriented toward the aqueous medium, and the polyester resin particles adhere to the core particle surface in a form oriented in the aqueous medium. Is also possible. As a result, the polyester resin particles can be densely attached to the surface of the core particles with a uniform thickness, and it is estimated that a thin shell layer can be formed on the surface of the core particles. Further, the affinity between the styrene acrylic copolymer segment constituting the styrene acrylic modified polyester of the shell and the styrene acrylic copolymer resin constituting the core particle promotes the orientation of the shell to the core particle surface. Conceivable.

  In this way, by having a carbon-carbon unsaturated bond in the polyester molecule, a certain degree of hydrophilicity is imparted to the polyester molecule, and an environment in which the polyester resin particles easily adhere to the core particle surface is formed. It is presumed that the formation of a thin layer of the shell is promoted.

  Further, there is an advantage that a structure in which the polyester segment and the styrene acrylic copolymer segment are molecularly bonded can be formed without preparing the above-mentioned “compound for molecularly bonding the polyester segment and the styrene acrylic copolymer segment”. . Therefore, it is preferable because the number of types of compounds necessary for producing the styrene-acrylic modified polyester is reduced, and the production process of the resin is simplified to contribute to productivity improvement.

Such an aliphatic unsaturated dicarboxylic acid preferably has a structure represented by the following general formula (A). That is,
General formula (A); HOOC- (CR < ¹ > = CR < ² >) n-COOH
R ¹ and R ² in the above formula are a hydrogen atom, a methyl group or an ethyl group, and may be the same or different from each other. N is an integer of 1 or 2.

  The ratio of the aliphatic unsaturated carboxylic acid represented by the general formula (A) to the total polyvalent carboxylic acid used for forming the polyester segment is preferably 25 mol% or more and 75 mol% or less, preferably 30 mol%. More preferred are those of 60 mol% or less.

Next, specific examples of the polyhydric alcohol will be described. Examples of the polyhydric alcohol that can be used to form the polyester segment include known dihydric alcohols and trihydric or higher alcohols. As a specific example of a dihydric alcohol, for example,
Examples include ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, and the like.

Moreover, as a specific example of trihydric or higher alcohol, for example,
Examples include glycerin, pentaerythritol, hexamethylol melamine, hexaethylol melamine, and tetramethylol benzoguanamine.

  The polyester segment is formed by polycondensation reaction of a polyvalent carboxylic acid and a polyhydric alcohol in the presence of a catalyst, and a known catalyst can be used.

  Next, the compound which forms a styrene acrylic copolymer segment is demonstrated. In the present invention, since the shell resin expresses affinity for the core particles to be described later and bonds them firmly, and the shell is formed on the surface of the core particles with a uniform thickness, the shell resin is used. A styrene acrylic modified polyester is used as the resin.

The polyester segment constituting the styrene acrylic modified polyester used in the present invention is formed by addition polymerization of at least a styrene monomer and an acrylate ester monomer. The styrenic monomer here includes those having a structure having a known side chain or functional group in the styrene structure in addition to styrene represented by the structural formula of CH ₂ ═CH—C ₆ H _5. . In addition to the acrylic ester compounds and methacrylic ester compounds represented by CH ₂ = CHCOOR (R is an alkyl group), the acrylic ester monomers referred to here are acrylic ester derivatives and methacrylic ester derivatives. Such a structure includes a vinyl ester compound having a known side chain or functional group.

  Specific examples of styrene monomers and acrylate monomers capable of forming styrene acrylic copolymer segments are shown below, but they are used to form styrene acrylic copolymer segments used in the present invention. The possibilities are not limited to those shown below.

First, specific examples of the styrene monomer include the following. That is,
Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn- Hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene and the like.

Further, specific examples of the acrylate monomer include the following acrylate monomers and methacrylic acid monomers. Examples of the acrylate monomers include the following: Can be mentioned. That is,
Methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, acrylic acid Phenyl and the like.

Examples of the methacrylic acid ester monomer include the following. That is,
Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, methacrylic acid Phenyl, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate and the like.

  These acrylic acid ester monomers or methacrylic acid ester monomers can be used alone or in combination of two or more. That is, forming a copolymer using a styrene monomer and two or more kinds of acrylate monomers, and forming a copolymer using a styrene monomer and two or more kinds of methacrylate monomers Either a styrene monomer, an acrylate monomer and a methacrylic acid ester monomer can be used together to form a copolymer.

  Moreover, when forming a styrene acrylic copolymer segment, the relative ratio of these styrene monomers and acrylate monomers is such that the glass transition temperature (Tg) calculated by the FOX equation shown below. It is preferable to adjust so that it may be in the range of 35 ° C to 60 ° C, more preferably in the range of 30 ° C to 50 ° C.

FOX formula: 1 / Tg = Σ (Wx / Tgx)
Wx in the above formula represents the mass fraction of monomer x, and Tgx represents the glass transition temperature of the homopolymer of monomer x. Here, the aforementioned “compound that forms a structure in which a polyester segment and a styrene acrylic copolymer segment are molecularly bonded” is not used when calculating the glass transition temperature.

  Next, physical properties of the shell resin containing the styrene acrylic modified polyester resin used in the present invention will be described. The shell resin used in the present invention has a glass transition temperature of 50 ° C. to 70 ° C. from the viewpoint of fixing properties such as low-temperature fixing properties and fixing separation properties and from the viewpoint of heat resistance such as heat-resistant storage properties and blocking resistance. ° C is preferred, and 50 to 65 ° C is more preferred. From the same viewpoint, the softening point temperature is preferably 80 ° C to 110 ° C.

  The glass transition temperature of the resin for shell can be measured, for example, by the method (DSC method) defined by ASTM (American Society for Testing and Materials) D3418-82.

Moreover, the measurement of the softening point temperature of resin for shells is performed in the following procedure, for example. First, in an environment of 20 ° C. ± 1 ° C. and 50% RH ± 5% RH, 1.1 g of shell resin is placed in a petri dish and leveled, and left for 12 hours or more. Next, pressurization of 3.82 × 10 ⁷ Pa (3820 kg / cm ² ) is performed for 30 seconds with a commercially available molding machine “SSP-10A (manufactured by Shimadzu Corporation)”, and a cylindrical molded sample having a diameter of 1 cm is obtained. create.

Next, this molded sample was subjected to a hole (1 mm diameter) of a cylindrical die by a commercially available flow tester “CFT-500D (manufactured by Shimadzu Corporation)” in an environment of 24 ° C. ± 5 ° C. and 50% RH ± 20% RH. Extrusion is performed from the end of preheating using a 1 cm diameter piston. The offset method was measured with a load of 196 N (20 kgf), a starting temperature of 60 ° C., a preheating time of 300 seconds, a temperature increase rate of 6 ° C./min, and a melting temperature measurement method of the temperature increase method with an offset value of 5 mm. The temperature T _offset is _defined as the softening point temperature of the shell resin.

  Next, the core particles constituting the toner produced in the present invention will be described. The core particle constituting the toner produced in the present invention contains a styrene acrylic copolymer formed by using a vinyl polymerizable monomer having an ester group in at least a molecular structure as a binder resin. is there. This styrene acrylic copolymer can be produced, for example, by carrying out a polymerization reaction with a mass ratio of vinyl polymerizable monomer having an ester group in the molecular structure being 25% by mass or more and 40% by mass or less. .

  By the way, in the present invention, a thin and uniform shell is formed on the surface of the core particle, making it possible to produce toner particles having both low-temperature fixability and heat-resistant storage stability and excellent durability. Yes. One condition for producing toner particles having such performance is to produce core particles having a smooth surface. Examples of the method of smoothing the surface of the core particle include a method of controlling the heating temperature and the fusing time in the step of aggregating and fusing the resin particles when preparing the core particles by the emulsion association method.

  That is, in the process of agglomerating and fusing the resin particles, by setting the heating temperature higher and setting the fusing time longer, the resin particle agglomerates become rounded core particles, and the surface is also smooth. It will become something. In addition to the process of agglomerating and fusing the resin particles, setting the heating temperature in the aging process in which the reaction system is heat-treated subsequent to this process to a high temperature and setting the treatment time to be long can also be used. This is a preferable measure for smoothness.

  The styrene acrylic copolymer contained in the core particles will be further described. As described above, the styrene acrylic copolymer contained in the core particle in the present invention is formed using a vinyl polymerizable monomer having an ester group in the molecular structure. A typical example of the “vinyl polymerizable monomer having an ester group therein” will be described.

First, the styrene acrylic copolymer referred to in the present invention is formed by performing radical polymerization using at least a styrene monomer and an acrylate monomer described later. Here, the styrene monomer includes styrene represented by the structural formula of CH ₂ ═CH—C ₆ H ₅ as well as those having a structure having a known side chain or functional group in the styrene structure. Is.

The acrylic acid ester monomer has a functional group having an ester bond in the side chain. _{Specifically,} CH 2 = CHCOOR (R is an alkyl group) other acrylic acid ester monomer represented _by, methacrylic acid ester represented by _{CH 2 = C (CH 3)} COOR (R is an alkyl group) Vinyl-based ester compounds such as monomers are included. That is, the acrylate monomer corresponds to the “vinyl polymerizable monomer having an ester group in the molecular structure” in the present invention. A methacrylic acid ester compound is mentioned.

  Specific examples of the styrene monomer and the acrylate monomer capable of forming a styrene acrylic copolymer are shown below, but for forming the core particles of the toner used in the present invention. Usable ones are not limited to those shown below.

First, examples of the styrene monomer include the following. That is,
Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn- Hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene and the like.

The acrylic ester monomers are typically the following acrylic ester monomers and methacrylic ester monomers. Examples of the acrylic ester monomers include the following. It is done. That is,
Methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, acrylic acid Examples of methacrylic acid ester monomers such as phenyl include the following. That is,
Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, methacrylic acid Phenyl, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate and the like.

  These acrylic acid ester monomers or methacrylic acid ester monomers can be used alone or in combination of two or more. That is, forming a copolymer using a styrene monomer and two or more kinds of acrylate monomers, and forming a copolymer using a styrene monomer and two or more kinds of methacrylate monomers Either a styrene monomer, an acrylate monomer and a methacrylic acid ester monomer can be used together to form a copolymer.

  In the present invention, the mass ratio of the vinyl polymerizable monomer having an ester group in the molecular structure typified by the above-mentioned acrylic acid ester monomer or methacrylic acid ester monomer is 25% by mass or more and 40% by mass or less. Core particles are formed using the styrene acrylic copolymer formed as described above.

  In addition to the copolymer formed only with the styrene monomer and the acrylate monomer described above, the styrene-acrylic copolymer includes, in addition to the styrene monomer and the acrylate monomer. Some are formed by using general vinyl monomers together. Although the vinyl monomer which can be used together when forming the styrene acrylic copolymer said by this invention below is illustrated, the vinyl monomer which can be used together is not limited to what is shown below.

(1) Olefins Ethylene, propylene, isobutylene, etc. (2) Vinyl esters Vinyl propionate, vinyl acetate, vinyl benzoate, etc. (3) Vinyl ethers Vinyl methyl ether, vinyl ethyl ether, etc. (4) Vinyl ketones Vinyl methyl ketone, Vinyl ethyl ketone, vinyl hexyl ketone, etc. (5) N-vinyl compounds N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, etc. (6) Other vinyl compounds such as vinyl naphthalene, vinyl pyridine, acrylonitrile, methacrylo Acrylic acid or methacrylic acid derivatives such as nitrile and acrylamide, etc. Moreover, it is also possible to produce a resin having a crosslinked structure using the following polyfunctional vinyls. Specific examples of the polyfunctional vinyls are shown below. That is,
Divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a vinyl monomer having an ionic dissociation group in such a side chain, and specific examples of the ionic dissociation group include, for example, a carboxyl group, a sulfonic acid group, and a phosphoric acid group. It is done. Specific examples of these vinyl monomers having an ionic dissociation group are shown below.

  First, specific examples of the vinyl monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, and the like. .

  Specific examples of the vinyl monomer having a sulfonic acid group include styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, and the like. Furthermore, specific examples of the vinyl monomer having a phosphate group include, for example, acid phosphooxyethyl methacrylate and 3-chloro-2-acid phosphooxypropyl methacrylate.

  When forming the styrene acrylic copolymer used in the present invention, the content of the styrene monomer and the acrylate monomer is not particularly limited, and the softening point temperature of the binder resin and the glass transition It is possible to adjust appropriately from the viewpoint of adjusting the temperature. Specifically, the content of the styrene monomer is preferably 40 to 95% by mass and more preferably 50 to 80% by mass with respect to the entire radical polymerizable monomer. Moreover, 5-60 mass% is preferable with respect to the whole radical polymerizable monomer, and, as for content of an acrylic ester monomer, 10-50 mass% is more preferable.

  The molecular weight of the styrene acrylic copolymer formed by radical polymerization is preferably 2,000 to 1,000,000 in terms of weight average molecular weight (Mw). Further, the number average molecular weight (Mn) is preferably 1,000 to 100,000. Moreover, 1.5-100 are preferable and, as for molecular weight distribution (Mw / Mn), 1.8-70 are more preferable. Fixing step when print preparation is performed using the prepared toner by setting the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the styrene acrylic copolymer within the above ranges. This is effective in suppressing the occurrence of the offset phenomenon. The glass transition point temperature of the styrene acrylic copolymer formed by radical polymerization is preferably 30 to 70 ° C, and the softening point temperature is preferably 80 to 170 ° C. When the glass transition point temperature and softening point temperature are in the above ranges, good fixability can be obtained.

  The number average molecular weight Mn and the weight average molecular weight Mw of the resin constituting the toner can be calculated by a molecular weight measurement method. Hereinafter, a molecular weight measurement procedure by gel permeation chromatography (GPC) using tetrahydrofuran (THF), which is one of typical examples of the molecular weight measurement method, as a column solvent will be described.

  Specifically, 1 ml of THF (using a degassed sample) is added to 1 mg of a measurement sample, and stirred sufficiently using a magnetic stirrer at room temperature to be sufficiently dissolved. Next, after processing with a membrane filter having a pore size of 0.45 μm to 0.50 μm, it is injected into the GPC apparatus.

  The measurement conditions of GPC are measured by stabilizing the column at 40 ° C., flowing THF at a flow rate of 1 ml / min, and injecting about 100 μl of a sample having a concentration of 1 mg / ml. As the column, it is preferable to use a combination of commercially available polystyrene gel columns. For example, a combination of Shodex GPC KF-801, 802, 803, 804, 805, 806, 807 manufactured by Showa Denko KK, or TSKgel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, TSK guard manufactured by Tosoh Corporation There are combinations.

  As the detector, a refractive index detector (RI detector) or a UV detector is preferably used. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve created using monodisperse polystyrene standard particles. About 10 points are preferably used as polystyrene for preparing a calibration curve.

  The molecular weight measurement can be performed, for example, under the following measurement conditions.

(Measurement condition)
Apparatus: HLC-8020 (manufactured by Tosoh Corporation)
Column: GMHXLx2, G2000HXLx1
Detector: At least one of RI and UV Eluent flow rate: 1.0 ml / min Sample concentration: 0.01 g / 20 ml
Sample volume: 100 μl
Calibration curve: produced with standard polystyrene As described above, the toner produced according to the present invention has a styrene-acrylic copolymer molecular chain bonded to a polyester molecular chain on the core particle surface containing a styrene-acrylic copolymer resin. The core-shell toner has a modified polyester resin with a different structure attached and coated.

  Next, a toner manufacturing method according to the present invention will be described.

  As described above, the toner produced in the present invention has a core shell in which the surface of core particles containing a styrene acrylic copolymer resin is coated with a modified polyester resin in which a styrene acrylic copolymer molecular chain is molecularly bonded to a polyester molecular chain. Structure toner.

  The method for producing a toner according to the present invention is a so-called polymerization method in which a polymerizable monomer is polymerized and particles are formed while controlling the shape and size at the same time. The polymerization method can form toner particles while controlling the shape and diameter of the particles in the production process, and is optimal for producing a small-diameter toner capable of faithfully reproducing a minute dot image. In the present invention, a core-shell toner is prepared by coating a core particle surface with a shell containing the above-described modified polyester resin by a polymerization method.

  Specifically, an emulsion association method in which resin particles of around 100 nm are formed in advance by an emulsion polymerization method or a suspension polymerization method, and toner particles are formed by agglomerating and fusing the resin particles is preferable. In the emulsion association method, core particles having a smooth surface can be produced by controlling the conditions of the resin particle aggregation / fusion process and the subsequent aging process.

Hereinafter, an example of preparing a toner having a core-shell structure by an emulsion association method will be described. In the emulsification association method, a toner is generally prepared through the following procedure. That is,
(1) Preparation process of core forming resin particle dispersion (2) Preparation process of colorant particle dispersion (3) Aggregation / fusion process of core resin particles (4) First aging process (5) Shelling process (6) Second aging step (7) Cooling step (8) Washing step (9) Drying step (10) External additive treatment step In the present invention, as described above, when the core particles are produced, aggregation / fusion is performed. By setting the heating temperature higher in the process and setting the fusing time longer, the aggregated resin particles become rounded and at the same time a smooth surface is formed. Further, by setting the heating temperature in the aging step in which the reaction system is heat-treated subsequent to the aggregation / fusion step to a higher temperature for a longer time, core particles having a smooth surface can be produced.

  Hereinafter, each step will be described.

(1) Production process of resin particle dispersion In this process, a polymerizable monomer that forms the resin particles for the core is charged into an aqueous medium and polymerized to form resin fine particles having a size of about 120 nm. It is a process. In the present invention, at this step, at least a styrene monomer and an acrylate monomer are charged and dispersed in an aqueous medium, and these polymerizable monomers are polymerized by a polymerization initiator to thereby styrene acrylic copolymer. The resin particles are prepared. In this way, resin particles for the core are formed.

(2) Step of producing colorant particle dispersion This is a step of producing a colorant particle dispersion having a size of about 110 nm by dispersing a colorant in an aqueous medium.

(3) Aggregation / fusion process of core resin particles (core particle formation)
This step is a step of aggregating the aforementioned resin particles and colorant particles in an aqueous medium, and simultaneously aggregating these particles to produce core particles. In this step, an alkali metal salt or alkaline earth metal salt is added as an aggregating agent to an aqueous medium in which resin particles and colorant particles are mixed, and then heated at a temperature equal to or higher than the glass transition temperature of the resin particles. The agglomeration is advanced to simultaneously fuse the resin particles.

  Specifically, the resin particles and the colorant particles produced by the above-described procedure are added to the reaction system, and a coagulant such as magnesium chloride is added to simultaneously aggregate the resin particles and the colorant particles. They are fused together to form aggregated resin particles (core particles). When the size of the core particles reaches the target size, a salt such as saline is added to stop the aggregation.

  In this step, when the heating temperature is set high and the fusing time is set long, the aggregated resin particles (core particles) become rounded and the surface becomes smooth at the same time. In this way, core particles having a smooth surface can be produced.

(4) First aging step This step is a step of aging until the shape of the core particles is changed to a desired shape by heat-treating the reaction system subsequent to the aggregation / fusion step. Even in this step, it is possible to produce core particles with a smooth surface by setting the heating temperature higher and setting the treatment time longer.

(5) Shelling step In this step, the shell-forming resin particles prepared by the above-described method are added to the core particle dispersion formed in the first ripening step, and the core particle surface is covered with the resin particles. And forming a shell. Specifically, a shell is formed by adding resin particles of a modified polyester obtained by molecularly bonding a styrene acrylic copolymer molecular chain to a polyester molecular chain, and the modified polyester strongly adheres to the core particle. A strong shell can be formed.

  That is, since a modified polyester in which a styrene acrylic copolymer molecular chain is bonded to a polyester molecular chain is used for the shell forming resin, the shell forming resin exhibits an appropriate affinity for the core particle surface. A strong adhesive force can be expressed. Moreover, dispersibility can be appropriately expressed between the shell-forming resin particles. In other words, the presence of the styrene-acrylic copolymer segment relaxes the affinity between the polyesters and develops dispersibility between the shell-forming resin particles, avoiding the aggregation of the shell-forming resin particles. And promotes non-uniform adhesion to the surface of the core particles. In this way, by using a modified polyester resin in which a styrene acrylic copolymer molecular chain is molecularly bonded to a polyester molecular chain, it has a strong adhesion to the core particles and has a uniform thickness without unevenness. Shell formation is possible.

(6) Second ripening step In this step, following the shelling step, the reaction system is heat-treated to enhance the shell coating on the surface of the core particles, and the shape of the toner base particles becomes a desired shape. It is a process of aging until it becomes.

(7) Cooling step This step is a step of cooling (rapid cooling) the dispersion of the toner base particles. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

(8) Washing step This step includes a step of solid-liquid separating the toner base particles from the toner base particle dispersion liquid cooled to a predetermined temperature in the above step, and a toner base that has been solid-liquid separated into a wet cake-like aggregate It consists of a cleaning process for removing deposits such as surfactants and flocculants from the particle surface.

  In the washing treatment, the washing treatment is performed until the electrical conductivity of the filtrate reaches a level of, for example, 10 μS / cm. As the filtration method, there are known processing methods such as a centrifugal separation method, a vacuum filtration method using Nutsche, etc., a filtration method using a filter press, etc., and there is no particular limitation.

(9) Drying Step This step is a step of drying the washed toner base particles to obtain dried toner base particles. Examples of the dryer used in this step include known dryers such as spray dryers, vacuum freeze dryers, and vacuum dryers, stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, and rotating dryers. It is also possible to use a type dryer, a stirring type dryer or the like.

  Further, the amount of water contained in the dried toner base particles is preferably 5% by mass or less, and more preferably 2% by mass or less. In addition, when the toner base particles that have been dried are agglomerated with a weak interparticle attractive force, the agglomerates may be crushed. Here, a mechanical crushing device such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used as the crushing treatment device.

(10) External additive treatment step This step is a step of preparing a toner by adding and mixing external additives as necessary to the surface of the dried toner base particles. In the present invention, monodispersed spherical particles having a number average primary particle size of 50 nm or more and 150 nm are added as external additives in this step.

  Through the above steps, a core-shell toner can be produced by an emulsion association method. For the reasons described above, the core-shell toner according to the present invention is preferably prepared by an emulsion association method.

  Next, the colorant that can be used in the toner produced in the present invention will be described with specific examples. First, known colorants can be used for the toner according to the present invention. Specific colorants are shown below.

  As the black colorant, for example, carbon black such as furnace black, channel black, acetylene black, thermal black and lamp black, and magnetic powder such as magnetite and ferrite can be used.

  Examples of the colorant for magenta or red include C.I. I. Pigment Red 2, 3, 5, 6, 7, 15, 15, 48: 1, 53: 1, 57: 1, 60, 63, 64, 68, the same 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 139, 144, 149, 150, 163, 166, 170, 177, 178, 184, 202, 206, 207, 209, 222, 238, 269, and the like.

  Examples of the colorant for orange or yellow include C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 12, 14, 15, 17, 74, 83, 93, 94, 138, 155, 162, 180, 185, and the like.

  Further, as a colorant for green or cyan, C.I. I. Pigment Blue 2, 3, 15, 15, 15: 2, 15: 3, 15: 4, 16, 17, 17, 60, 62, 66, C.I. I. Pigment Green 7 etc.

  Examples of the dye include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 2, 6, 14, 15, 16, 19, 21, 21, 33, 44, 56, 61, 77, 79, 80, 81, 82, the same 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, etc.

  These colorants can be used alone or in combination of two or more as required. Further, the amount of the colorant added is in the range of 1 to 30% by mass, preferably 2 to 20% by mass, based on the whole toner, and a mixture thereof can also be used. The number average primary particle size varies depending on the type, but is preferably about 10 to 200 nm.

  Next, external additives that can be used in the toner according to the present invention will be described. As described above, the toner according to the present invention can be prepared by adding and mixing external additives as necessary to the surface of the toner base particles that have been dried in the production process (external). Additive processing step). In this external additive treatment step, toner such as inorganic fine particles or organic fine particles having a number average primary particle size of 4 to 800 nm is added as an external additive (= external additive) to produce a toner. By adding the external additive, the fluidity and chargeability of the toner are improved, and the cleaning property is improved. The type of the external additive is not particularly limited, and examples thereof include known inorganic fine particles, organic fine particles, and lubricants exemplified below.

  As the inorganic fine particles, conventionally known fine particles can be used. For example, silica, titania, alumina, strontium titanate fine particles and the like are preferable. Moreover, what hydrophobized these inorganic fine particles can also be used as needed.

  Specific examples of the silica fine particles include commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., HVK-2150 manufactured by Hoechst, H -200, commercially available products TS-720, TS-530, TS-610, H-5, MS-5, etc. manufactured by Cabot Corporation.

  As the titania fine particles, for example, commercially available products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercially available products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, JA- 1. Commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd. Commercial products IT-S, IT-OA, IT-OB, IT- manufactured by Idemitsu Kosan Co., Ltd. OC etc.

  Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd., and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

  As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. Specifically, homopolymers such as styrene and methyl methacrylate and copolymers thereof can be used.

  In addition, a lubricant can be used to further improve the cleaning property and transfer property, and examples thereof include the following higher fatty acid metal salts. That is, salts of zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, salts of manganese, iron, copper, magnesium, etc., zinc palmitate, salts of copper, magnesium, calcium, etc., linoleic acid There are salts of zinc, calcium and the like, and zinc and calcium of ricinoleic acid.

  The addition amount of these external additives and lubricants is preferably 0.1 to 10.0% by mass with respect to the whole toner.

  Next, an aggregating agent, a polymerization initiator, a dispersion stabilizer, a surfactant, and the like used when a toner is produced by an emulsion association method will be described.

  In the present invention, as described above, toner base particles are formed by aggregating and fusing resin particles, colorant particles, and the like in a dispersion obtained by dispersing resin particles, colorant particles, etc. in an aqueous medium. . Although the flocculant which can be used by this invention is not specifically limited, What is selected from a metal salt is used suitably. For example, monovalent metal salts such as alkali metal salts such as sodium, potassium and lithium, for example, divalent metal salts such as calcium, magnesium, manganese and copper, and trivalent metals such as iron and aluminum. There is salt. Specific examples of the salt include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, and manganese sulfate. Among these, divalent metal is particularly preferable. Salt. When a divalent metal salt is used, agglomeration can be promoted with a smaller amount. These may be used alone or in combination of two or more.

When the binder resin constituting the toner according to the present invention is formed using a vinyl polymerizable monomer, a known oil-soluble or water-soluble polymerization initiator can be used. Specific examples of the oil-soluble polymerization initiator include the following azo or diazo polymerization initiators and peroxide polymerization initiators. That is,
(1) Azo or diazo polymerization initiator 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1 -Carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile, etc. (2) peroxide-based polymerization initiators benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl Peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4 4-t-butylperoxycyclohexyl) propane, tris (T-butylperoxy) triazine In the case of forming the resin particles by emulsion polymerization is a water-soluble radical polymerization initiators can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide and the like.

  A known chain transfer agent can also be used for adjusting the molecular weight of the resin particles. Specific examples include octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, n-octyl-3-mercaptopropionic acid ester, terpinolene, carbon tetrabromide, and α-methylstyrene dimer.

  In the present invention, a polymerizable monomer dispersed in an aqueous medium is polymerized, and a resin particle or the like dispersed in the aqueous medium is aggregated and fused to produce a toner. It is preferable to use a dispersion stabilizer that is stably dispersed in the mixture. Examples of the dispersion stabilizer include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, Examples include barium sulfate, bentonite, silica, and alumina. In addition, polyvinyl alcohol, gelatin, methylcellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, higher alcohol sodium sulfate and the like which are generally used as surfactants can also be used as the dispersion stabilizer.

  Further, when polymerization is performed using a polymerizable monomer in an aqueous medium, it is necessary to uniformly disperse oil droplets of the polymerizable monomer in the aqueous medium using a surfactant. In this case, usable surfactants are not particularly limited, but for example, the following ionic surfactants can be used as preferable ones. Examples of the ionic surfactant include a sulfonate, a sulfate ester salt, and a fatty acid salt. Examples of the sulfonate include sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, and 3,3-disulfonediphenyl. Urea-4,4-diazo-bis-amino-8-naphthol-6-sulfonate sodium, o-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4 -Sodium diazo-bis-β-naphthol-6-sulfonate.

  Examples of sulfate salts include sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, and sodium octyl sulfate. Fatty acid salts include sodium oleate, sodium laurate, sodium caprate, sodium caprylate, Examples include sodium caproate, potassium stearate, and calcium oleate.

  Nonionic surfactants can also be used. Specifically, polyethylene oxide, polypropylene oxide, a combination of polypropylene oxide and polyethylene oxide, esters of polyethylene glycol and higher fatty acids, alkylphenol polyethylene oxide, higher fatty acids and Examples include polyethylene glycol esters, higher fatty acid and polypropylene oxide esters, sorbitan esters, and the like.

  Examples of the present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

1. 1. Production of resin particles for shell 1-1. Preparation of “Styrene Acrylic Modified Polyester Resins 1 to 3” (1) Preparation of “Styrene Acrylic Modified Polyester Resin 1” Styrene acrylic modified polyester in which a styrene acrylic copolymer molecular chain is molecularly bonded to a polyester molecular chain by the following procedure. A dispersion of “resin particle 1 for shell” containing resin was prepared. That is,
To a reaction vessel equipped with a nitrogen introduction device, dehydration tube, stirring device and thermocouple,
Bisphenol A propylene oxide 2-mole adduct 500 parts by weight Terephthalic acid 154 parts by weight Fumaric acid 45 parts by weight Tin octylate 2 parts by weight are charged, a polycondensation reaction is performed at 230 ° C. for 8 hours, and further at 8 kPa for 1 hour. After continuing the polycondensation reaction, it was cooled to 160 ° C. In this way, polyester molecules were formed.

Next, 10 parts by mass of acrylic acid was added at a temperature of 160 ° C., mixed and held for 15 minutes, and then a mixture of the following compounds was added dropwise over 1 hour with a dropping funnel. That is,
Styrene 142 parts by mass n-butyl acrylate 35 parts by mass Polymerization initiator (di-t-butyl peroxide) 10 parts by mass After the addition, the addition polymerization reaction was carried out for 1 hour while maintaining the temperature at 160 ° C., and then 200 ° C. The temperature was raised to 10 kPa and held for 1 hour. In this manner, “styrene acrylic modified polyester resin 1” having a styrene acrylic copolymer molecular chain content of 20% by mass constituting the styrene acrylic modified polyester molecule was produced.

(2) Production of “styrene acrylic modified polyester resin 2” In addition to the production of “styrene acrylic modified polyester resin 1”, the addition amount of styrene was changed to 30 parts by mass and the addition amount of n-butyl acrylate was changed to 7 parts by mass. Produced “styrene acrylic modified polyester resin 2” by following the same procedure. “Styrene acrylic modified polyester resin 2” had a content of 5% by mass of the molecular chain of styrene acrylic copolymer constituting the styrene acrylic modified polyester molecule.

(3) Production of “styrene acrylic modified polyester resin 3” The amount of styrene used in the production of “styrene acrylic modified polyester resin 1” was changed to 243 parts by mass, and the amount of n-butyl acrylate added was changed to 61 parts by mass. Otherwise, the same procedure was followed to produce “styrene acrylic modified polyester resin 3”. The “styrene acrylic modified polyester resin 3” had a content of styrene acrylic copolymer molecular chains constituting the styrene acrylic modified polyester molecules of 30% by mass.

1-2. 4. Production of “Shell Resin Particles 1-13” (1) Production of “Shell Resin Particle 1” 100 parts by mass of the above “styrene acrylic modified polyester resin 1” was dissolved in 400 parts by mass of ethyl acetate, and then 5. A resin solution was formed by adding 25 parts by weight of a 0% by weight aqueous sodium hydroxide solution. This resin solution was put into a container having a stirring device containing 638 parts by mass of an aqueous solution having a sodium lauryl sulfate concentration of 0.26% by mass, and stirred in the container to prepare a mixed solution.

  The mixed liquid is passed through a commercially available rotor / stator type dispersion processing device “CLEAMIX CLM-0.8S” (manufactured by M Technique Co., Ltd.), and the rotor peripheral speed is set to 15 m / s. Distributed processing was performed. In the dispersion process, the mixed liquid processed by the dispersion processing apparatus is stored in a receiving tank provided in a recovery section at the nozzle outlet, and sent to the dispersion processing apparatus by a pump from the bottom of the receiving tank to perform continuous operation. It is. This dispersion treatment was performed for 45 minutes with respect to 1 kg of the mixed solution, thereby preparing an emulsion in which the resin solution particles were uniformly dispersed. When the resin solution particles in the emulsion were measured with a laser diffraction particle size distribution analyzer “LA-750” (manufactured by Horiba, Ltd.), the volume average particle size was 140 nm. Next, the emulsion is heated to 40 ° C., and using a diaphragm vacuum pump “V-700” (manufactured by BUCHI), the ethyl acetate is distilled off under a reduced pressure of 150 hPa to obtain a volume average particle size A dispersion of 115 nm “shell resin particles 1” was prepared.

(2) Production of “resin particle 2 for shell” In the production of “resin particle 1 for shell”, when the resin solution is formed, the addition amount of “styrene acrylic modified polyester resin 1” is 175 parts by mass, ethyl acetate Was added to 325 parts by mass. Further, the dispersion treatment time by the dispersion treatment apparatus was changed to 60 minutes with respect to 1 kg of the mixed solution, and the other procedures were followed to produce “shell resin particles 2”. It was 135 nm when the volume average particle diameter of “resin particle 2 for shell” was measured by the laser diffraction particle size distribution analyzer. The volume average particle diameter of the resin solution particles formed when the “shell resin particles 2” were produced was 165 nm.

(3) Production of “resin particle 3 for shell” In the production of “resin particle 1 for shell”, when forming a resin solution, the addition amount of “styrene acrylic modified polyester resin 1” is 250 parts by mass, ethyl acetate. Was added to 250 parts by mass. Moreover, the dispersion treatment time by the dispersion treatment apparatus was changed to 30 minutes with respect to 1 kg of the mixed solution, and the other procedures were followed to produce “shell resin particles 3”. It was 165 nm when the volume average particle diameter of "the resin particle 3 for shell" was measured with the said laser diffraction type particle size distribution measuring apparatus. The volume average particle diameter of the resin solution particles formed when producing the “shell resin particles 3” was 210 nm.

(4) Preparation of “Shell Resin Particle 4” When forming the resin solution in the preparation of “shell resin particle 1”, “styrene acrylic modified polyester resin 2” is used instead of “styrene acrylic modified polyester resin 1”. 300 parts by mass was dissolved in 200 parts by mass of ethyl acetate to prepare a resin solution. Further, the rotor peripheral speed of the dispersion processing apparatus was changed to 10 m / s, and the dispersion processing time by the dispersion processing apparatus was changed to 30 minutes with respect to 1 kg of the mixed solution. Otherwise, the same procedure was followed to produce “shell resin particles 4”. The volume average particle size of “shell resin particles 4” was 200 nm when measured by the laser diffraction particle size distribution analyzer. The volume average particle diameter of the resin solution particles formed when the “shell resin particles 4” were produced was 250 nm.

(5) Production of “shell resin particles 5” In the production of “shell resin particles 4”, 100 parts by mass of “styrene acrylic modified polyester resin 2” when forming a resin solution was changed to 400 parts by mass of ethyl acetate. A resin solution was prepared by dissolving. Moreover, the rotor peripheral speed of the dispersion processing apparatus was changed to 20 m / s, and the dispersion processing time by the dispersion processing apparatus was changed to 45 minutes with respect to 1 kg of the mixed liquid. Otherwise, the same procedure was followed to produce “shell resin particles 5”. The volume average particle diameter of the “shell resin particles 5” was measured by the laser diffraction particle size distribution measuring apparatus to be 70 nm. The volume average particle diameter of the resin solution particles formed when producing the “shell resin particles 5” was 80 nm.

(6) Production of “shell resin particles 6” In the production of “shell resin particles 1”, the rotor peripheral speed of the dispersion treatment apparatus was changed to 20 m / s, and the dispersion treatment time by the dispersion treatment apparatus was mixed. It changed into 60 minutes with respect to 1 kg of liquids. Otherwise, the same procedure was followed to produce “shell resin particles 6”. The volume average particle diameter of “shell resin particles 6” was measured with the laser diffraction particle size distribution analyzer, and found to be 45 nm. The volume average particle diameter of the resin solution particles formed when producing the “shell resin particles 6” was 50 nm.

(7) Production of “shell resin particles 7” In the production of “shell resin particles 2”, the rotor peripheral speed of the dispersion treatment apparatus was changed to 20 m / s, and the dispersion treatment time by the dispersion treatment apparatus was mixed. It changed into 75 minutes with respect to 1 kg of liquids. Otherwise, the same procedure was followed to produce “shell resin particles 7”. The volume average particle size of “Shell Resin Particles 7” measured by the laser diffraction particle size distribution analyzer was 70 nm. The volume average particle diameter of the resin solution particles formed when producing the “shell resin particles 7” was 75 nm.

(8) Production of “shell resin particles 8” In the production of “shell resin particles 3”, the rotor peripheral speed of the dispersion treatment apparatus was changed to 20 m / s, and the dispersion treatment time by the dispersion treatment apparatus was mixed. It changed into 60 minutes with respect to 1 kg of liquids. Otherwise, the same procedure was followed to produce “shell resin particles 8”. The volume average particle diameter of the “shell resin particles 8” was measured by the laser diffraction particle size distribution analyzer, and found to be 90 nm. The volume average particle size of the resin solution particles formed when the “shell resin particles 8” were produced was 100 nm.

(9) Production of “Shell Resin Particles 9” In the production of “shell resin particles 1”, 200 parts by mass of “styrene acrylic modified polyester resin 3” instead of “styrene acrylic modified polyester resin 1” was mixed with ethyl acetate. A resin solution was formed by dissolving in 300 parts by mass. Moreover, the rotor peripheral speed of the dispersion processing apparatus was changed to 20 m / s, and the dispersion processing time by the dispersion processing apparatus was changed to 75 minutes with respect to 1 kg of the mixed liquid. Otherwise, the same procedure was followed to produce “shell resin particles 9”. The volume average particle diameter of the “shell resin particles 9” was measured with the laser diffraction particle size distribution analyzer, and found to be 65 nm. The volume average particle size of the resin solution particles formed when the “shell resin particles 9” were produced was 75 nm.

(10) Production of “Shell Resin Particles 10” When forming the resin solution in the production of “shell resin particles 9”, 300 parts by mass of “styrene acrylic modified polyester resin 3” was dissolved in 200 parts by mass of ethyl acetate. To form a resin solution. Further, the dispersion treatment time by the dispersion treatment apparatus was changed to 60 minutes with respect to 1 kg of the mixed solution, and the other procedures were followed to produce “shell resin particles 10”. The volume average particle size of “Shell Resin Particles 10” measured by the laser diffraction particle size distribution analyzer was 80 nm. The volume average particle diameter of the resin solution particles formed when producing the “shell resin particles 10” was 100 nm.

(11) Production of “resin particle 11 for shell” The resin solution used for the production of “resin particle 3 for shell” and 638 parts by mass of a 0.26 mass% aqueous sodium lauryl sulfate solution were mixed to prepare a mixed solution. . Next, 0.3 mmφ zirconia media was used as a dispersion medium, and the mixture liquid was subjected to dispersion treatment using a commercially available bead mill “Ultra Apex Mill UAM-015 (manufactured by Kotobukiken Co., Ltd.)”. Then, the particle diameter change of the resin solution particles with the lapse of the dispersion treatment time by the bead mill is observed, and when the volume average particle diameter becomes 105 nm, the dispersion treatment is stopped to thereby obtain “shell resin particles 11”. Produced. In addition, the particle size change observation of the resin solution particles was performed using the laser diffraction particle size distribution measuring apparatus.

(12) Production of “resin particle 12 for shell” In the production of “resin particle 11 for shell”, the resin solution used for the production of the mixed liquid is changed to that used for the production of “resin particle 9 for shell”. Then, the dispersion treatment was performed using the above-mentioned commercially available bead mill. The change in the particle diameter of the resin solution particles with the lapse of the dispersion treatment time by the bead mill was observed, and the dispersion treatment was stopped when the volume average particle diameter reached 125 nm, thereby producing “shell resin particles 12”. . The volume average particle diameter of the “shell resin particles 12” is measured by the laser diffraction particle size distribution measuring apparatus described above.

(13) Production of “resin particle 13 for shell” In the same procedure as the production of “resin particle 11 for shell”, dispersion treatment is performed with the above-described commercially available bead mill, and resin solution particles with the lapse of dispersion treatment time with the bead mill. The particle size change was observed, and the dispersion treatment was stopped when the volume average particle size reached 80 nm. By adopting this procedure, “shell resin particles 13” were produced. The volume average particle diameter of the “shell resin particles 13” is measured by the above-mentioned laser diffraction particle size distribution measuring apparatus.

  Styrene acrylic modified polyester resin used when producing the above “resin particles 1-13 for shell”, resin content at the time of forming the resin solution, rotor / stator dispersion treatment conditions at the time of forming the resin solution particles (rotor peripheral speed) , Treatment time), and the volume average particle diameter of the formed resin solution particles and resin particles are shown in Table 1 below.

2. 2. Preparation of “toner particles 1 to 13” 2-1. Preparation of “core resin particle A” (1) First-stage polymerization Sodium lauryl sulfate 2 which is an anionic surfactant is attached to a reaction vessel equipped with a stirrer, a temperature sensor, a temperature controller, a cooling pipe and a nitrogen introducing device. Part by weight and 2900 parts by weight of ion-exchanged water were added to prepare an aqueous anionic surfactant solution. The temperature was raised to 80 ° C. while stirring the aqueous anionic surfactant solution at a stirring speed of 230 rpm under a nitrogen stream.

After the temperature increase, an initiator solution in which 9 parts by mass of potassium persulfate (KPS) is dissolved in 200 parts by mass of ion-exchanged water is added, the liquid temperature of the surfactant aqueous solution is set to 78 ° C., and the following compounds are contained. The monomer mixture was added dropwise over 3 hours. That is,
Styrene 540 parts by weight n-butyl acrylate 270 parts by weight Methacrylic acid 65 parts by weight n-octyl mercaptan 17 parts by weight After dropping, the mixture is heated and stirred at 78 ° C. for 1 hour to perform a polymerization reaction (first stage polymerization). A dispersion of “resin particles A1” was prepared.

(2) Second-stage polymerization Next, 1100 parts by mass of ion-exchanged water and 2 parts by mass of sodium lauryl sulfate were introduced into a reaction vessel equipped with a stirrer, a temperature sensor, a temperature controller, a cooling tube, and a nitrogen introduction device, and the interface An aqueous activator solution was prepared and heated to 90 ° C. After heating, 28 parts by mass of the above-mentioned “resin particles (A1)” and the following monomer mixture are added to the surfactant aqueous solution, and a mechanical dispersion device “Clearmix ( M. Technic Co., Ltd.) "for 4 hours to prepare a dispersion containing emulsified particles having a dispersed particle diameter of 350 nm.

The monomer mixture contains the following compound, and paraffin wax is added after dissolving the following monomer and n-octyl mercaptan, and heated to 85 ° C. to dissolve. That is,
Styrene 94 parts by weight n-butyl acrylate 60 parts by weight Methacrylic acid 11 parts by weight n-octyl mercaptan 5 parts by weight Paraffin wax (melting point 73 ° C.) 51 parts by weight In the emulsified particle dispersion, potassium persulfate (KPS) 2.5 An initiator solution in which parts by mass are dissolved in 110 parts by mass of ion-exchanged water is added, and this system is heated and stirred at 90 ° C. for 2 hours to perform a polymerization reaction (second stage polymerization). A dispersion was prepared.

(3) Third-stage polymerization Next, an initiator solution in which 2.5 parts by mass of potassium persulfate (KPS) was dissolved in 110 parts by mass of ion-exchanged water in the dispersion of the “resin particles A2” was added, The liquid temperature was set to 80 ° C., and a monomer mixed solution containing the following compound was added dropwise over 1 hour. That is,
Styrene 230 parts by mass n-butyl acrylate 100 parts by mass n-octyl mercaptan 5.2 parts by mass The above monomer mixture was added dropwise, followed by heating and stirring at 80 ° C. for 3 hours for polymerization reaction (third stage) Polymerization). Then, it cooled to 28 degreeC and produced the dispersion liquid of "resin particle A for cores".

  The “core resin particle A” produced by the above procedure is a styrene acrylic copolymer formed by setting the mass ratio of n-butyl acrylate, which is a polymerizable monomer having an ester bond, to 31% by mass, and has a glass transition temperature. Was 43 ° C.

2-2. Preparation of “Colorant Particle Dispersion Bk” While stirring a solution obtained by dissolving 90 parts by mass of sodium dodecyl sulfate in 1600 parts by mass of ion-exchanged water,
420 parts by mass of carbon black “Mogal L (Cabot)” was gradually added. Next, a “colorant particle dispersion Bk” was prepared by carrying out a dispersion treatment using a stirrer “CLEARMIX (M Technique Co., Ltd.)”.

2-3. Preparation of “toner particles 1 to 13” (1) Preparation of “toner particles 1” In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device,
"Core resin particle dispersion A" 270 parts by mass (solid content conversion)
Ion-exchanged water 1400 parts by mass “Colorant particle dispersion Bk” 120 parts by mass (solid content conversion)
Was introduced. Furthermore, a solution of 3 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate in 120 parts by mass of ion-exchanged water was added, the temperature of the solution was raised to 30 ° C., and then a 5 mol / liter sodium hydroxide aqueous solution was added. The pH was adjusted to 10.

  Next, an aqueous solution in which 35 parts by mass of magnesium chloride hexahydrate was dissolved in 35 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. The temperature started. The temperature was raised to 90 ° C. over 60 minutes, and the particles were aggregated and fused while maintaining the temperature at 90 ° C. In this way, “core particle A” was formed.

In this state, using “Multisizer 3 (manufactured by Beckman Coulter)”, the particle size of the agglomerated particles growing in the reaction vessel was measured, and when the volume-based median diameter was 6.0 μm,
"Resin particle dispersion 1 for shell" 30 parts by mass (solid content conversion)
Was added and stirring was continued until the “shell resin particles 1” in the dispersion liquid adhered to the surface of the “core particles A”. Then, a small amount of the reaction solution was taken out and centrifuged, and when the supernatant became transparent, an aqueous solution in which 150 parts by mass of sodium chloride was dissolved in 600 parts by mass of ion-exchanged water was added to stop particle growth. Furthermore, as the aging treatment, the liquid temperature was set to 90 ° C., and the mixture was heated and stirred to promote particle fusion. In this state, the fusion of the particles was advanced until the average circularity was 0.965 as measured by “FPIA-2100 (manufactured by Sysmex Corporation)”.

  Thereafter, the liquid temperature was cooled to 30 ° C., the pH of the liquid was adjusted to 2 using hydrochloric acid, and stirring was stopped. In this manner, “toner base particle dispersion 1” was produced.

  The “toner base particle dispersion 1” produced through the above steps is subjected to solid-liquid separation with a basket type centrifuge “MARKIII model number 60 × 40 (manufactured by Matsumoto Kikai Co., Ltd.)”, and the “toner base particle 1” is wet. A cake was formed.

  The wet cake was washed with ion exchange water at 45 ° C. until the electric conductivity of the filtrate reached 5 μS / cm using the basket-type centrifuge. After that, it is transferred to “Flash Jet Dryer (manufactured by Seishin Enterprise Co., Ltd.)” and dried until the water content becomes 0.5% by mass to produce “toner base particle 1” having a volume-based median diameter of 6.3 μm. did.

  Next, the following amount of the following external additive is added to 100 parts by mass of the above “toner base particle 1”, and external addition processing is performed with a Henschel mixer (manufactured by Mitsui Miike Mining Co., Ltd.) to obtain “toner particle 1”. Produced.

Hexamethylsilazane-treated silica (average primary particle size 12 nm, hydrophobicity 68)
1.0 part by mass n-octylsilane-treated titanium dioxide (average primary particle size 20 nm, hydrophobicity 63)
0.3 parts by mass The external addition treatment by the Henschel mixer was performed under the conditions of a peripheral speed of the stirring blade of 35 m / second, a treatment temperature of 35 ° C., and a treatment time of 15 minutes. “Toner particles 1” produced by the above procedure is a core-shell toner having a volume-based median diameter of 6.3 μm.

(2) Preparation of “Toner Particles 2 to 13” When forming a shell on the surface of the “core particle A” in the preparation of the “toner particle 1”, the “shell resin particle dispersion 1” is replaced with “shell”. “Toner particles 2 to 13” were prepared in the same manner except that the dispersions of resin particles 2 to 13 ”were used. “Toner particles 2 to 13” produced by the above procedure are all core-shell structured toners having a volume-based median diameter of 6.3 μm.

  Table 2 below shows the core resin particles and the shell resin particles used in the production of the “toner particles 1 to 13”. That is,

3. Evaluation Experiment The “toner particles 1 to 13” produced by the above procedure were evaluated for heat resistant storage resistance, crush resistance and chargeability with the following contents. Here, the evaluation of “toners 1 to 10” in which the resin particles for forming the shell of the styrene acrylic modified polyester resin are formed according to the configuration of the present invention is set to “Examples 1 to 10” as shown in Table 2 above. The evaluation of “toners 11 to 13” in which the resin particles for shell formation are formed by a bead mill is referred to as “comparative examples 1 to 3”.

(1) Evaluation of heat-resistant storage property of toner particles The heat-resistant storage property of the toner was evaluated by the following procedure. First, 0.5 g of each toner is put into a 10 ml glass bottle having an inner diameter of 21 mm, the lid is closed, and the mixture is shaken 600 times with a tap denser “KYT-2000” (manufactured by Seishin Enterprise Co., Ltd.). And left in an environment with a humidity of 35% RH for 2 hours. Next, the toner was placed on a 48 mesh (aperture 350 μm) sieve so as not to be crushed, set in a “powder tester (manufactured by Hosokawa Micron)”, and fixed with a pressing bar and a knob nut.

  The “powder tester” was adjusted to a vibration intensity of a feed width of 1 mm, and vibration was applied for 10 seconds. Thereafter, the amount of toner remaining on the sieve was measured, and the ratio of the remaining toner was calculated to determine the toner aggregation rate (mass%). This was evaluated as heat resistant storage stability.

The toner aggregation rate is calculated by the following formula:
Toner aggregation rate (mass%) = [residual toner mass on sieve (g) /0.5 (g)] × 100
Evaluation of heat-resistant storage property was performed based on the following criteria. That is,
A: Toner yield is less than 15% by mass (very good heat-resistant storage)
○: The toner aggregation rate is 15 mass% or more and 20 mass% or less (good heat-resistant storage property)
X: The toner aggregation rate exceeds 20% by mass (the toner has poor heat storage stability and cannot be used)
Among the above criteria, ◎ and ○ were accepted.

(2) Evaluation of toner particle crush resistance <Toner crush resistance>
10 g of each of “toner particles 1 to 13” prepared in the above procedure are weighed, and the toner particles are put in a polyethylene container together with 0.05 g of commercially available titanium oxide fine particles and 30 g of commercially available glass beads having a diameter of 3 mm, and are then mixed with a turbuler mixer. Mixing treatment was performed for 10 minutes. The particle size distribution of the toner particles before and after the mixing treatment was measured with a Coulter counter (manufactured by Nikkiso Co., Ltd.), and the obtained particle size distribution was compared with a number% of 4 μm or less before and after mixing and evaluated as follows. Of the following evaluation criteria, those that were evaluated as ○, ○, and △ were considered acceptable. That is,
(Evaluation criteria)
A: Number% increase ratio of 4 μm or less before mixing treatment-less than 3.0% after mixing treatment ○: Number% increase ratio of 4 μm or less before mixing treatment-3.0% or more after mixing treatment Less than 0% Δ: Increase ratio of number% of 4 μm or less before mixing treatment—After mixing treatment 6.0% or more and less than 10.0% X: Increase ratio of number% of 4 μm or less before mixing treatment—after mixing treatment 10.0% or more.

<Damage by electron microscope observation>
The toner particles after the mixing treatment were observed with a commercially available transmission electron microscope (SEM), and the state of occurrence of chipping, peeling, and cracking of the toner particle surface, that is, the shell was evaluated as follows. Among the following evaluation criteria, ◎, ○, and Δ were regarded as acceptable. That is,
(Evaluation criteria)
A: No chipping, peeling or cracking of the shell is observed. ○: Less than 5% of the toner particles in which the chipping, peeling or cracking of the shell is observed Δ: Toner particles in which the chipping, peeling or cracking of the shell is observed 5% or more and less than 10% of the total X: 10% or more of the toner particles in which chipping, peeling or cracking of the shell layer is observed (3) Evaluation of initial chargeability of toner particles “Toner particles 1 to 13” In addition, a ferrite carrier coated with a silicone resin and having a volume average particle diameter of 35 μm is added so that the toner concentration is 6%, and is added to a “micro type V-type mixer (manufactured by Tsutsui Rikenki Co., Ltd.)”. The mixing process was performed for 30 minutes at 45 rpm. By this procedure, “Developers 1 to 13” were produced.

  The above “Developers 1 to 13” are mounted on a commercially available digital copying machine “bizhub PRO C6500” (manufactured by Konica Minolta Business Technologies, Inc.), and each toner particle is charged when the developing device is supplied to the digital copying machine. Sex was evaluated as follows. In other words, under normal temperature and humidity (20 ° C, 55% RH) environment, use a manuscript with a pixel rate of 75% and a large image area, and make 1000 prints in a print mode that consumes a lot of toner (supply amount). It was. After 1000 prints were produced, the stain due to toner scattering in the machine due to charging rise failure and the image blur of the printed image were visually evaluated.

(Evaluation criteria)
◎: No toner stains in the machine and no fading of the print image ○: No toner stains in the machine, but slight fading occurred at the rear end of the print image, but no problem in practical use ×: Toner stain in the machine, print image It is a problem in practical use because of fading. 10,000 continuous prints were made. The continuous print is obtained by outputting a human face photo image, a halftone image, and a white background image on A4 plain paper.

  The above results are shown in Table 3.

  As shown in Table 3, “Examples 1 to 10” in which the toner particles formed with the resin particles for the styrene acrylic modified polyester shell prepared by the method of the present invention were evaluated are good in heat-resistant storage property and charge rising performance. Results were obtained. This is presumably due to the formation of toner particles in which the shell is uniformly formed on the surface and the core is not exposed. It was also confirmed that a durable toner was produced. On the other hand, “Comparative Examples 1 to 3” in which toner particles formed using resin particles for styrene acrylic-modified polyester shells produced by a bead mill method were evaluated, both of heat-resistant storage properties and charge rise performance did not reach acceptable levels. Thus, the results were different from those of “Examples 1 to 10”.

DESCRIPTION OF SYMBOLS 10 Dispersion processing apparatus 11 Flow path 12 Rotor 13 Gap 14 Stator 14a Hole T Toner particle A Core particle A1 Colorant A2 Resin B Shell B3 Resin

Claims (10)

At least on the surface of the core particles containing a resin and a colorant,
A method for producing toner particles comprising a step of forming a shell by adding resin particles containing a styrene acrylic modified polyester having a structure in which a styrene acrylic copolymer molecular chain is molecularly bonded to a polyester molecular chain,
The resin particles containing the styrene acrylic modified polyester are at least:
A resin solution obtained by dissolving a styrene acrylic modified polyester resin in an organic solvent and an aqueous medium are mixed to form a mixed solution,
Rotating the mixed liquid, and applying a shearing force to the mixed liquid in a gap through which the rotated mixed liquid passes, to form particles of the resin solution,
A method for producing toner particles, which is formed by removing an organic solvent from particles of the resin solution.   2. The method for producing toner particles according to claim 1, wherein a peripheral speed of a rotating means for rotating the mixed liquid is 10 m / sec or more and 20 m / sec or less. The gap through which the rotated mixed liquid passes is
Formed between a rotor for rotating the mixed liquid and a stator having a plurality of holes arranged concentrically around the rotor;
The shear force applied to the mixture is
The liquid flow generated when the liquid mixture is rotated by the rotor and the liquid flow generated when the liquid mixture is discharged from the hole of the stator, are generated. 3. A method for producing toner particles according to 1 or 2.   The method for producing toner particles according to claim 1, wherein the resin solution has a content of the styrene acrylic modified polyester resin of 20% by mass or more and 60% by mass or less. .   The particle diameter of the resin solution particles in a state where the resin solution particles are dispersed in the aqueous medium is 50 nm or more and 250 nm or less. Toner particle manufacturing method. Resin contained in the core particles,
6. The method for producing toner particles according to claim 1, wherein the toner particle contains at least a styrene acrylic copolymer.   The method for producing toner particles according to claim 1, wherein the styrene-acrylic modified polyester has a content of a styrene-acrylic copolymer of 5% by mass to 30% by mass. The said styrene acrylic modified polyester is formed using the aliphatic unsaturated carboxylic acid represented by the following general formula (A), The any one of Claims 1-7 characterized by the above-mentioned. A method for producing toner particles.
General formula (A): HOOC- (CR < ¹ > = CR _< ² _> ) _n- COOH
(In the formula, R ¹ and R ² are a hydrogen atom, a methyl group or an ethyl group, and may be the same or different from each other. N is an integer of 1 or 2.)   9. The toner according to claim 1, wherein the styrene-acryl-modified polyester has a styrene-acrylic copolymer molecular chain molecularly bonded to an end of the polyester molecular chain. Particle production method.   The styrene acrylic modified polyester is a polymer that undergoes a polymerization reaction of a styrene monomer and an acrylate monomer in the presence of the polyester molecular chain to form the styrene acrylic copolymer molecular chain. The method for producing toner particles according to claim 1, wherein the toner particles are produced.

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