JP2001356518A - Toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner with which an image of high printing density can be obtained without fog, thinning or filming even for long-term repeated printing in various environments even when recycled paper is used as the transfer material. SOLUTION: The toner is obtained by adding as external additives magnetite particles having 1×104 to 1×1012 Ω.cm volume specific resistance, organic fine particles having -100 to -400 μC/g blow-off charge amount and if necessary other fine particles to color particles having 1.0 to 1.3 sphericity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic latent image formed by an electrophotographic method, an electrostatic recording method, or the like. In particular, the present invention relates to a toner free from fogging, blurring and filming even when recycled paper is used as a transfer material.

[0002]

2. Description of the Related Art Conventionally, an electrostatic latent image formed in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus is first developed with toner, and then the formed toner image is used as required. After being transferred onto a transfer material such as paper, it is fixed by various methods such as heating, pressing, and solvent vapor.
As a toner, generally, a colorant, a charge control agent, a release agent, and the like are melt-mixed and uniformly dispersed in a thermoplastic resin serving as a binder resin component to form a composition, and then the composition is pulverized. ,
A pulverized toner that obtains colored particles by classification, a colorant, a charge control agent, and a release agent are dissolved or dispersed in a polymerizable monomer that is a binder resin raw material, and after adding a polymerization initiator,
Suspension polymerized toner obtained by suspending in an aqueous dispersion medium containing a dispersion stabilizer, heating to a predetermined temperature to initiate polymerization, and filtering, washing, dehydrating and drying after polymerization to obtain colored particles, emulsification Particles of a binder resin containing a polar group obtained by polymerization, and particles containing a colorant and a charge control agent are stirred at a temperature higher than the glass transition temperature of the binder resin to associate the particles. Emulsion polymerization toners that obtain colored particles by filtration, drying and drying are used.

In recent years, there has been a growing demand for higher image quality, such as higher image quality and stable image quality even in poor environments such as high temperature, high humidity, and low temperature, low humidity. ing. In response to such demands, there have been proposals to respond to the design of the binder resin and to include functional components such as a charge control agent and a release agent. There is also a proposal to improve the image quality of the toner by adding an external additive such as fine particles. For example, JP-A-6-194864 discloses that
By using silica fine particles and organic fine particles together as an external additive, sufficient fluidity and chargeability of the polymerized toner are ensured,
It discloses that good image quality can be obtained. JP-A-4-186251 discloses, as an external additive, a fluidity improver such as titanium oxide or alumina, organic fine particles,
It has been proposed to use a silicon-containing compound having a weight average particle size of 0.2 to 2.5 μm. In the examples of the publication, a two-component developer obtained by adding such a three-component external additive to a polyester-based pulverized toner is a method for electrophotographic color images using an organic semiconductor (OPC) photoconductor. When obtained, it has been shown to enable continuous printing of clear images without damaging the photoreceptor. Also, Japanese Patent Application Laid-Open
In JP-A-327194, spherical oxide particles selected from silica and titanium oxide having a particle size of 20 to 50 nm as external additives to a non-magnetic pulverized toner,
It is reported that good image quality can be formed even when there is a change in temperature or humidity when used in combination with spherical oxide particles selected from silica and titanium oxide having a thickness of nm.

Recently, from the viewpoint of environmental protection, recycled paper has been widely used mainly in offices. In offices, there are many opportunities for continuous printing, and there is a tendency to use a machine with a high printing speed. Good image quality is required even when printing continuously on recycled paper with a high-speed machine.

[0005]

SUMMARY OF THE INVENTION The present inventors have found that when conventional toner is applied to recycled paper, fogging is likely to occur in printing during durability. An object of the present invention is to provide a toner capable of obtaining an image having a high print density without fogging, blurring, filming, etc., even when using recycled paper as a transfer material and in various environments, even when printing for a long time. Is to provide.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve this object, and as a result, have found that an external additive containing organic fine particles having a specific range of blow-off charge and magnetite particles is used. It has been found that the above object can be achieved by using the same, and the present invention has been completed based on this finding.

[0007] Thus, according to the present invention, it contains colored particles and an external additive, and the external additive contains magnetite particles and organic fine particles having a blow-off charge of -100 to -400 µc / g. A toner is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The toner of the present invention contains colored particles and an external additive. The external additive used in the present invention contains magnetite particles and organic fine particles having a blow-off charge of −100 to −400 μc / g.

The blow-off charge of the organic fine particles is -10
0 to -400 [mu] c / g, preferably -100 to -250
μc / g. If it is smaller than -100 [mu] c / g, fog increases during printing by a printer, and conversely, -40 [mu] c / g.
If it is larger than 0 μc / g, the fluidity is reduced, and fuzziness is likely to occur.

The amount of blow-off charge of the organic fine particles can be controlled by the type of monomer used for polymerization, the polymerization initiator, the particle size of the organic fine particles, the purification of the organic fine particles after polymerization, and the like. As a control method depending on the type of the monomer, the monomer is negatively charged when the monomer contains a polar group such as an acid group, and is positively charged when the monomer contains an amino group or an ammonium group. With respect to the polymerization initiator, when a persulfate such as potassium persulfate is used, the polymerization initiator becomes negatively charged and becomes 2,2 ′.
When an azo compound such as -azobis [2-methyl-N- (2-hydroxyethyl) propionamide] is used, it is positively charged. Regarding the particle size, the larger the particle size, the smaller the charge amount. Conversely, the smaller the particle size, the larger the charge amount. As a purification method, purification can be performed using ultrafiltration, a ceramics filter, or the like. When purification is sufficiently performed, the charge amount increases.

The organic fine particles can be obtained by known emulsion polymerization, dispersion polymerization or the like. However, the emulsifier used in this case is difficult to control the charge amount, so that soap-free polymerization without using an emulsifier is preferable. . For the soap-free polymerization, a known method can be adopted. When employing soap-free polymerization, it is preferable to use an ionic monomer such as sodium styrenesulfonate or potassium styrenesulfonate in order to impart colloidal stability to the organic fine particles. The amount of these monomers is not particularly limited, but is usually 0.01 to 20 relative to all monomers.
%, Preferably 0.05 to 10% by weight. If the amount is small, the colloidal stability of the particles is insufficient, and the particles may aggregate during polymerization. Conversely, if the amount is small, it may be difficult to control the chargeability.

As the polymerization initiator, ordinary water-soluble initiators can be used. However, 2,2'-azobis (2-amidinopropane) dihydrochloride, , 4'-Azobis (4-cyanovaleric acid), 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2 '
-Azobis [2-methyl-N- (1,1-bis (hydroxymethyl) -2-hydroxyethyl) propionamide], 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide And the like are preferred.

The organic fine particles are not particularly limited except for the amount of blow-off charge, but from the viewpoint of suppressing blocking between the particles, the compound constituting the fine particles has a glass transition temperature or melting point of usually 80 to 250 ° C., preferably 90 to 250 ° C. 2
00 ° C. Examples of the compound constituting the organic fine particles include an aromatic vinyl polymer, a (meth) acrylate polymer, and an aromatic vinyl- (meth) acrylate copolymer, and the like. ,
Core-shell particles having a shell portion of a (meth) acrylate polymer are preferred from the viewpoint of controlling the chargeability.

As a method for obtaining organic fine particles having a core-shell type structure, for example, a method in which a monomer for a core is polymerized and then a monomer for a shell is added to form a shell polymer, There is a method of obtaining a core-shell structure by phase separation during the reaction. Among them, the method of polymerizing the core monomer and then adding the shell monomer to form a shell polymer is preferable because the choice of monomers is wide. The method of adding the shell monomer during the reaction of the core monomer is not particularly limited, and any of a batch addition method, a sequential addition method, and a continuous addition method may be employed. In order to produce complete core-shell type particles, the shell monomer is added at a polymerization conversion of the core portion of 80% or more, more preferably 90% or more.

The number average particle size of the organic fine particles is not particularly limited, but is usually 0.1 to 1 μm, preferably 0.1 to 0.1 μm.
8 μm. Also, its sphericity is not particularly limited,
Usually, it is 1.0 to 1.3, preferably 1.0 to 1.2. If the number average particle size is small, filming may not be prevented. On the contrary, if the number average particle size is large, the fluidity may decrease. If the sphericity is large, the transferability may decrease.

The amount of the organic fine particles is not particularly limited, but is usually 0.05 to 1 based on 100 parts by weight of the colored particles.
Parts by weight, preferably 0.1 to 0.5 parts by weight. If the amount is small, filming is likely to occur, and if the amount is large, the fluidity is deteriorated and the film is likely to be worn.

Although the magnetite particles are not particularly limited,
Its volume resistivity is usually 1 × 10 ⁴ to 1 × 10 ^12.
Ω · cm, preferably 1 × 10 ⁶ to 1 × 10 ¹² Ω · c
m. If this value is small, fog increases during printing by the printer, and if it is large, blurring increases under low-temperature and low-humidity environments.

As a method for setting the volume resistivity of the magnetite particles in the above range, for example, a method of coating the surface of the magnetite particles with an aluminum compound can be employed. Specifically, the surface of the particles is coated by adding an aluminum compound to a water suspension obtained by dispersing the magnetite particles and mixing and stirring, or by adjusting the pH as necessary, It is obtained through a process such as filtration, washing, drying, degassing, and crushing.

As the aluminum compound, aluminum acetate, aluminum sulfate, aluminum chloride, aluminum nitrate and the like can be used. The amount of the aluminum compound used for coating is not particularly limited, but is usually 0.1 to 100 parts by weight of magnetite.
It is 1 to 50 parts by weight, preferably 1 to 30 parts by weight. If the amount is small, the volume resistivity is low, so that fogging is easy. On the other hand, if it is large, charging becomes high under low temperature and low humidity, which may easily cause blurring.

The number average particle size of the magnetite particles is not particularly limited, but is usually 0.05 to 0.5 μm, preferably 0.1 to 0.3 μm. If the number average particle size is small, filming may not be prevented, whereas if it is large, the fluidity may be reduced.

The amount of the magnetite particles is not particularly limited, but is usually 0.01 to 100 parts by weight of the colored particles.
To 0.5 part by weight, preferably 0.05 to 0.3 part by weight. If this amount is small, the electrification becomes high and it is easy to lose,
Conversely, when the amount is increased, the charge becomes low and fogging is likely to occur.

Fine particles other than those described above can be contained in the external additive. In particular, it is preferable to add inorganic fine particles as the external additive since the fluidity is improved and fogging hardly occurs.
As the inorganic fine particles, inorganic fine particles other than magnetite,
For example, silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, barium titanate, strontium titanate and the like can be mentioned. Among them, silica is preferable because fog at the time of printing is small.

These inorganic fine particles preferably have a hydrophobicity of 30 to 90% as measured by a methanol method. The inorganic fine particles having such a degree of hydrophobicity can be obtained by performing a hydrophobic treatment with a silane coupling agent, silicone oil, or the like.

The number average particle size of the inorganic fine particles is not particularly limited, but is usually 5 to 40 nm, preferably 10 to 30 nm.
It is. If the number average particle size is small, the charge density increases at low temperature and low humidity, resulting in a decrease in print density.

The amount of the inorganic fine particles is not particularly limited, but is usually 0.1 to 2 parts by weight, preferably 0.3 to 1.5 parts by weight, per 100 parts by weight of the colored particles. If the amount is small, the fluidity is reduced, and the fluidity is easily caused. On the other hand, if the amount is large, the fluidity becomes too good and the fog is easily caused.

The colored particles that can be used in the present invention usually contain a binder resin, a coloring agent and other additives. The colored particles are (1) a colorant, a charge control agent, a release agent, and the like, melted and mixed in a thermoplastic resin to be a binder resin component to uniformly disperse the composition. Amorphous colored particles obtained by pulverizing and classifying the product, (2) dissolving or suspending a colorant, a charge control agent, a release agent, etc. in a polymerizable monomer which is a binder resin raw material; After addition of the polymerization initiator, it is obtained by dispersing in an aqueous dispersion medium containing a dispersion stabilizer, heating to a predetermined temperature to start suspension polymerization, and filtering, washing, dehydrating and drying after completion of the polymerization. Substantially spherical colored particles, (3) primary particles of a binder resin containing a polar group obtained by emulsion polymerization are aggregated by adding a coloring agent and a charge control agent to form secondary particles, and further, are bound. The particles associated by stirring at a temperature higher than the glass transition temperature of the resin are filtered, Raspberry-shaped colored particles obtained by 燥 (JP 63-1862
53) and the like, and any of them can be used. From the viewpoint of obtaining a toner which gives good image quality on recycled paper, substantially spherical colored particles obtained by the suspension polymerization method of (2) are used. preferable.

The colored particles have a sphericity (Sc / Sr) of 1.0 to 1.0 obtained by dividing the area (Sc) of a circle whose diameter is the absolute maximum length of the particles by the substantial projected area (Sr) of the particles. It is preferable to use those having a value of 3, more preferably 1.0 to 1.2. When the sphericity is increased, the fluidity is reduced, and the spheroidity may be easily reduced.

As specific examples of the binder resin, resins widely used in conventional toners such as polystyrene, styrene-butyl acrylate copolymer, polyester resin and epoxy resin can be used.

The colored particles are not particularly limited, but have a volume average particle size (dv) of usually 3 to 12 μm, preferably 4 to 1 μm.
0 μm. Moreover, it is desirable that the ratio (dv / dn) of the volume average particle diameter (dv) to the number average particle diameter (dn) is in the range of 1.0 to 1.3.

The colored particles can be particles having a structure obtained by combining two different polymers inside (core layer) and outside (shell layer) of the particles, so-called core-shell structure (also called capsule structure). Core-shell structured particles are preferable because the internal low softening point substance can be encapsulated with a higher softening point substance, and the balance between lowering the fixing temperature of the toner and preventing aggregation during storage can be achieved. The colored particles having a core-shell structure may be obtained by a pulverization method, or may be obtained by a suspension polymerization method or an emulsion polymerization method.

In the case of core-shell particles, the volume average particle size of the core particles is not particularly limited, but is usually 2 to 10 μm, preferably 2 to 9 μm, more preferably 3 to 8 μm.
The volume average particle diameter (dv) / number average particle diameter (dp) is not particularly limited either, but is usually 1.7 or less, preferably 1.
5 or less, more preferably 1.3 or less.

The weight ratio of the core layer to the shell layer of the core-shell particles is not particularly limited, but is usually 80/20 to 99.
Used at 9 / 0.1. When the ratio of the shell layer is smaller than the above ratio, the storage stability is deteriorated. On the other hand, when the ratio is larger than the above ratio, fixing at a low temperature may be difficult.

The average thickness of the shell layer of the core-shell particles is as follows:
Usually 0.001 to 1.0 μm, preferably 0.003 to
It is considered to be 0.5 μm, more preferably 0.005 to 0.2 μm. When the thickness is large, the fixability is reduced, and when the thickness is small, the storability may be reduced. In addition,
It is not necessary that the entire surface of the core particle forming the colored particle having the core-shell structure is covered with the shell layer, and it is sufficient that a part of the surface of the core particle is covered with the shell layer. . When the core particle diameter of the core-shell particles and the thickness of the shell layer can be observed by an electron microscope, it can be obtained by directly measuring the size and the shell thickness of the particles randomly selected from the observation photograph. When it is difficult to observe the core and the shell, it can be calculated from the particle size of the core particles and the amount of the monomer forming the shell used in producing the toner.

The method for producing the core-shell particles is as follows.
Methods such as a spray drying method, an interface reaction method, an in situ polymerization method, and a phase separation method can be adopted. In particular, an in situ polymerization method or a phase separation method is preferable from the viewpoint of production efficiency.

The toner of the present invention comprises colored particles and an external additive,
It is obtained by mixing with a high-speed stirrer such as a Henschel mixer.

[0036]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited to these examples. In addition, parts and%
Are by weight unless otherwise specified. In the present example, evaluation was made by the following method.

[Evaluation Method] (Volume Average Particle Size and Particle Size Distribution) The volume average particle size (dv) of the colored particles and the particle size distribution, ie, the ratio (dv / d) of the volume average particle size to the number average particle size (dp). dp) was measured with a Multisizer (manufactured by Beckman Coulter). The measurement with this multisizer was performed with an aperture diameter of 100 μm.
m, medium: Isoton II, concentration 10%, number of measured particles:
The test was performed under the condition of 100,000 pieces. (Number average particle diameter) The number average particle diameter of silica, titanium oxide, and organic fine particles was determined by taking an electron micrograph of each particle, and using the image processing / analysis apparatus Luzex IID (manufactured by Nireco Corporation) to determine the frame area. Area ratio of particles to:
The circle equivalent diameter was calculated under the conditions of a maximum of 2% and the total number of particles treated: 100, and the average value was calculated.

(Sphericity) The sphericity (Sc / Sr) obtained by dividing the area (Sc) of a circle whose diameter is the absolute maximum length of a particle by the actual projected area (Sr) of the particle is represented by an electron microscope of each particle. A photograph is taken, and the photograph is taken by an image processing / analysis apparatus Luzex IID (manufactured by Nireco Co., Ltd.).
It is an average value of 100 measured and calculated on 0 conditions. (Degree of hydrophobicity) The degree of hydrophobicity by the methanol method is determined according to the following measuring method. 0.2 g of treated inorganic fine particles
Is weighed into a 500 ml beaker, 50 ml of pure water is added, and methanol is added below the liquid level while stirring with a magnetic stirrer. The point at which no sample is observed on the liquid surface is defined as the end point, and the degree of hydrophobicity is calculated by the following equation. Degree of hydrophobicity (%) = (X / (50 + X)) × 100 X; Methanol usage (ml)

(Blow-off charge amount) A carrier (TEFV manufactured by Powder Tech Co., Ltd.) was placed in a 100 cm ³ ball mill pot.
−150/250) 59.7 g and organic fine particles 0.3 g are put into a 200 cc SUS pot, stirred for 30 minutes, and rotated at 150 rpm to frictionally charge, and a blow-off charge amount measuring device TB-200 (Toshiba Chemical Co., Ltd.) Was blown off at a nitrogen pressure of 1 kg / cm, and the charge amount per unit weight was measured. (Electrical Resistance) The volume resistivity was measured at a temperature of 30 using a dielectric loss measuring instrument (trade name: TRS-10, manufactured by Ando Electric Co., Ltd.).
The temperature was measured at a temperature of 1 ° C. and a frequency of 1 kHz.

(Fog) Recycled paper is set in a commercially available non-magnetic one-component developing system printer (12-sheet machine), and a developer to be evaluated is put in a developing device of the printer.
℃, humidity 50% (N / N) environment, temperature 35 ℃, humidity 80
% (H / H) environment and temperature 10 ° C., humidity 20% (L / H
L) After standing overnight in each environment of the environment, continuous printing is performed at 5% print density, printing is stopped after printing is started (at the time of printing 10 sheets) and after printing 10,000 sheets, and the photoconductor after development is stopped. The toner in the upper non-image area was adhered to an adhesive tape (Scotch Mending Tape 810-3-18 manufactured by Sumitomo 3M Limited). It was attached to a printing paper, and its whiteness (B) was measured with a whiteness meter (manufactured by Nippon Denshoku). Similarly, only the adhesive tape was affixed to the printing paper, the whiteness (A) thereof was measured, and the fog value was calculated by the following formula: fog (%) = (AB). A smaller value indicates less fog.

(Fray) A recycled paper is set in a commercially available non-magnetic one-component developing system printer (12-sheet machine), and a developer to be evaluated is put in a developing device of the printer.
℃, humidity 50% (N / N) environment-5% after standing overnight
Continuous printing was performed at the printing density, and black solid printing was performed every 500 sheets, and the number of occurrences of blurring was counted. The final number of printed sheets was 10,000. Those without a number in the table indicate that no blurring occurred even after continuous printing of 10,000 sheets. (Filming) Recycled paper is set in a commercially available non-magnetic one-component developing system printer (12-sheet machine), and a developer to be evaluated is put in a developing device of this printer. The temperature is 23 ° C., the humidity is 50% (N / N). N) Under an environment-After standing day and night, continuous printing was performed at a print density of 5%, halftone printing was performed every 500 sheets, and the number of sheets where white blurring occurred was counted. The final number of printed sheets was 10,000. Those without numbers in the table indicate that filming did not occur even after continuous printing of 10,000 sheets.

REFERENCE EXAMPLE 1 100 parts of styrene, 2.5 parts of sodium styrenesulfonate, 1.5 parts of sodium chloride and 4000 parts of ion-exchanged water were added to a nitrogen-replaced reaction vessel equipped with a stirrer, and mixed. To 80 ° C. After heating, 2,2'-azobis [2-methyl-N-
(2-Hydroxyethyl) propionamide] (trade name: "VA-80", manufactured by Wako Pure Chemical Industries, Ltd.) 3% aqueous solution 50
0 parts were added to initiate the polymerization. On the way, while measuring the polymerization conversion, when the conversion reached 30%, 0.1 part of t-dodecyl mercaptan was added, and the conversion was measured 7 hours after the start of the polymerization, and was 98%. Next, 400 parts of methyl methacrylate was added over 15 minutes, and further 3 parts were added.
After the polymerization was continued for a period of time, the polymerization was stopped by cooling with water to obtain an aqueous dispersion of core-shell type organic fine particles. At this time, the polymerization conversion rate was 97%, and the number average particle diameter of the organic fine particles was 0.3.
8 μm, sphericity was 1.13.

The aqueous dispersion of the organic fine particles was subjected to ultrafiltration (UF module ACV-3050 manufactured by Asahi Kasei Corporation).
Purification was performed until the electric conductivity of the aqueous phase reached 30 μS.
Then, after water was distilled off with a rotary evaporator, the resultant was dried in a vacuum dryer at 50 ° C. all day and night. The organic fine particles pseudo-agglomerated by drying were crushed into primary particles in a mortar to prepare core-shell type organic fine particles A. The blow-off charge was measured to be -150 [mu] C / g.

Reference Example 2 Organic fine particles B were prepared in the same manner as in Reference Example 1 except that sodium styrenesulfonate was used in an amount of 5.0 parts. The blow-off charge amount of the organic fine particles B is -250 μC / g, and the number average particle size is 0.32 μm.
m and sphericity were 1.10.

Reference Example 3 Organic fine particles C were prepared in the same manner as in Reference Example 1, except that 1.0 part of sodium styrene sulfonate and 1.0 part of sodium chloride were used. The blow-off charge amount of the organic fine particles C was −50 μC / g, the number average particle diameter was 0.48 μm, and the sphericity was 1.19.

Reference Example 4 Organic fine particles D were prepared in the same manner as in Reference Example 1, except that sodium styrene sulfonate was 20.0 parts and the electric conductivity of purified water was 20 μS. The blow-off charge amount of the organic fine particles D is -580.
μC / g, the number average particle diameter was 0.29 μm, and the sphericity was 1.15.

(Example 1) 83 parts of styrene, 17 parts of n-butyl acrylate, carbon black (trade name "# 2
5B ", manufactured by Mitsubishi Chemical Corporation; primary particle size: 40 nm) 6 parts, charge control agent (trade name:" Spiron Black TRH ", manufactured by Hodogaya Chemical Co., Ltd.) 0.5 parts, divinylbenzene 0.6 parts, t-
One part of dodecyl mercaptan and two parts of Sasol wax (trade name “Paraflint Spray 30”, manufactured by Sasol) were dispersed at room temperature by a bead mill to obtain a uniform mixed solution. While stirring the mixture, the polymerization initiator t-
Butyl peroxy 2-ethylhexanoate (trade name;
5 parts of "Perbutyl O" (manufactured by NOF Corporation) were added, and stirring was continued until the droplets became uniform.

On the other hand, in an aqueous solution obtained by dissolving 9.5 parts of magnesium chloride (a water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water, and 4.8 parts of sodium hydroxide (alkali metal hydroxide) in 50 parts of ion-exchanged water. The aqueous solution in which was dissolved was gradually added under stirring to prepare a magnesium hydroxide colloid (poorly water-soluble metal hydroxide colloid) dispersion. The polymerizable monomer composition was charged into the colloid, and the mixture was subjected to high shear stirring at a rotation speed of 12000 rpm using a TK homomixer to granulate droplets of the polymerizable monomer mixture. The aqueous dispersion of the granulated polymerizable monomer mixture is put into a reactor equipped with a stirring blade, a polymerization reaction is started at 90 ° C., polymerization is performed for 8 hours, and then cooling is performed. I got

While stirring the aqueous dispersion of the polymer particles obtained above, sulfuric acid was added to adjust the pH to 4 or less, acid washing was performed, water was separated by filtration, and 500 parts of ion-exchanged water was newly added. In addition, the slurry was reslurried and washed with water. After that, dehydration and washing with water were repeated several times again, and the solid content was separated by filtration, followed by drying at 45 ° C. for 2 days and night with a drier to obtain colored particles. The volume average particle size of the colored particles is 7.8.
μm, volume average particle diameter (dv) / number average particle diameter (dp), which is an index of particle diameter distribution, was 1.25, and sphericity was 1.15.

100 parts of the obtained colored particles, 0.3 part of the organic fine particles A obtained in Reference Example 1, a volume resistivity value of 4.9 × 10 ⁷ Ω · cm, and a number average particle size of 0.18 μm
0.1 parts of magnetite particles and a number average particle diameter of 12 n
m, silica having a hydrophobicity of 64% (trade name “RX-20”).
0 ", manufactured by Nippon Aerosil Co., Ltd.) and mixed with a Henschel mixer for 10 minutes at 1400 rpm.
A toner was obtained. Printing evaluation was performed on the obtained toner. Table 1 shows the results.

[0051]

[Table 1]

(Examples 2 and 3, Comparative Examples 1 to 4) Evaluations were made in the same manner as in Example 1 except that the external additives were changed as shown in Table 1. Table 1 shows the results.

From the evaluation results of the toners in Table 1, the following can be understood. The toner of Comparative Example 1, which did not contain organic fine particles in the external additive, was liable to fog and filming occurred in continuous printing. The toner of Comparative Example 2 in which the blow-off charge amount of the organic fine particles is smaller than the range specified in the present invention is liable to cause fogging and to cause blurring in continuous printing. The toner of Comparative Example 3, which does not contain magnetite particles in the external additive,
Fog tends to occur, and blurring tends to occur in continuous printing.
The toner of Comparative Example 4 in which the blow-off charge amount of the organic fine particles is larger than the range specified in the present invention easily causes blurring in continuous printing. On the other hand, it can be seen that the toners of Examples 1 to 3 of the present invention hardly cause fogging, blurring and filming.

[0054]

According to the present invention, even when recycled paper is used as a transfer material, an image having a high print density without fog, blurring, filming, etc. even in a long-time durable printing in various environments can be obtained. An obtainable toner is provided.

Claims (1)

[Claims] Claims: 1. An ink composition comprising colored particles and an external additive, wherein the external additive and the magnetite particles have a blow-off charge of -100 to
A toner comprising -400 μc / g of organic fine particles.