JP2008133348A - Resin fine particle, method for producing resin fine particle, toner for developing electrostatic charge image and method for producing toner for developing electrostatic charge image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for developing electrostatic charge images capable of forming the stable images even when printing of a plurality of sheets is carried out without causing the problems in the toner for developing the electrostatic charge images prepared through a step of aggregating resin fine particles and forming particles. <P>SOLUTION: The resin fine particles have ≥5 to ≤30 ratio (Mw/Mn) of weight-average molecular weight Mw to number-average molecular weight Mn and ≥10 to ≤300 nm D<SB>50</SB>(median diameter) based on the volume. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic image developing toner comprising resin fine particles having a size of about 100 nm and particles formed by agglomerating the resin fine particles.

  In the field of electrophotographic image forming apparatuses such as copiers and printers, with the advancement of digital technology, high-resolution dot image reproduction of 1200 dpi (dpi: number of dots per inch: 2.54 cm) has recently been achieved. The technology to realize this has come to be required. As one of the means for accurately reproducing such a high-definition image, the reduction in the diameter of the toner has been studied, and the representative is an association type toner capable of forming particles while controlling the particle diameter and shape during the manufacturing process. The diameter of the polymerized toner is reduced (see, for example, Patent Document 1).

  Here, the association type toner is prepared through a process in which resin fine particles having a size of about 100 nm are prepared in advance and the fine particles are aggregated to form particles serving as a toner base. By controlling the environmental conditions, the size and shape of the particles can be controlled. As described above, by controlling the environmental conditions of the manufacturing process, it is possible to manufacture a toner having a size and a shape that can support high-definition image formation.

  By the way, in order to realize a toner capable of stably forming a high-definition image, in addition to obtaining particles having a desired size and shape by the environmental control in the aggregation process described above, It is also required to have performance. That is, the toner image transferred onto a support such as paper can be melted and solidified smoothly, or after being put into the image forming apparatus, it can be damaged even if it is subjected to agitation or conveyance in the developing apparatus. There is also a need for durability that does not have any. Further, since the problem of offset caused by toner adhesion to the surface of the photoreceptor or the fixing roller also hinders maintaining good image formation, a toner that does not cause offset is also required. These performances depend largely on the physical properties of the resin fine particles constituting the toner. In particular, the molecular weight is positioned as a large factor in determining the physical properties of the toner.

  Therefore, in order to realize a toner having desired performance, attempts have been made to achieve this problem by selecting, combining, and aggregating a plurality of types of resin fine particles having different molecular weights. (For example, see Patent Document 2).

  For example, in order to reduce the energy consumption of the image forming apparatus, there is a demand for a toner that can be fixed at a lower temperature than before. In order to realize such a toner, particles are formed by agglomerating resin fine particles having a relatively low molecular weight. On the other hand, in the case of realizing a toner having durability that does not easily break even when subjected to an impact in the apparatus, resin particles having a relatively high molecular weight are aggregated to form particles. In this way, it can be said that the molecular weight of the resin fine particles constituting the particles is in an important position in realizing a toner having desired performance.

Further, in the resin fine particle production process, it is required to form resin fine particles having a sharp molecular weight distribution in order to align the performance of the resin fine particles, and the polymerization environment at the time of fine particle production has also been studied. For example, paying attention to a reaction apparatus that performs a polymerization reaction, an invention of a resin fine particle production apparatus in which a plurality of stirring tank type reaction apparatuses are provided (see, for example, Patent Document 3) can be given.
JP 2000-214629 A JP 2001-290301 A JP 2003-40912 A

  As described above, in the association type toner, a plurality of types of resin fine particles having different molecular weights are selected and combined, and these resin fine particles are aggregated to realize a toner having desired performance. However, toner produced by agglomerating a plurality of types of resin fine particles having different molecular weights may cause fusing on the surface of the fixing roller, filming on the surface of the photoreceptor, There was a tendency to cause carrier contamination.

  The present invention relates to an electrostatic charge image developing toner produced through a process of forming particles by agglomerating resin fine particles, and an electrostatic charge image capable of forming a stable image without causing the above problems even when a large number of sheets are printed. An object is to provide a developing toner.

  The present invention is achieved by adopting the following configuration.

1.
A resin fine particle having a ratio of the weight average molecular weight Mw to the number average molecular weight Mn (Mw / Mn) of 5 or more and 30 or less, and a median diameter (D ₅₀ ) based on volume of 10 nm or more and 300 nm or less.

2.
In the method for producing resin fine particles, wherein a composition containing at least a monomer is emulsified and dispersed in an aqueous medium, and the emulsion-dispersed monomer is subjected to emulsion polymerization to produce particles.
A method for producing resin fine particles, comprising adding a chain transfer agent having a chain transfer constant at 50 ° C. of 10 to 40 to the monomer, followed by emulsion polymerization.

3.
At least in a method for producing resin fine particles obtained by emulsifying and dispersing a composition containing a monomer in an aqueous medium, and subjecting the emulsified and dispersed monomer to emulsion polymerization.
A ratio of the weight average molecular weight Mw to the number average molecular weight Mn (Mw / Mn) of the resin fine particles is 5 or more and 30 or less, and a median diameter (D ₅₀ ) based on volume is 10 nm or more and 300 nm or less. For producing resin fine particles.

4).
At least in the electrostatic image developing toner obtained by aggregating resin fine particles and colored particles,
2. A toner for developing an electrostatic charge image, comprising using the resin fine particles as described in 1 above.

5.
Production of an electrostatic charge image developing toner comprising at least a step of emulsifying and dispersing a monomer-containing composition in an aqueous medium, a step of emulsion-polymerizing the emulsified and dispersed monomer to produce resin fine particles, and a step of aggregating resin fine particles In the method
An electrostatic charge image developing toner comprising: a resin fine particle obtained by adding a chain transfer agent having a chain transfer constant at 50 ° C. of 10 to 40 to a monomer and emulsion polymerization as the resin fine particle. Production method.

6).
An electrostatic charge image developing toner comprising at least a step of emulsifying and dispersing a monomer-containing composition in an aqueous medium, a step of emulsion-polymerizing the emulsion-dispersed monomer to produce resin fine particles, and a step of aggregating the resin fine particles. In the manufacturing method,
As the resin fine particles, resin fine particles having a ratio of the weight average molecular weight Mw to the number average molecular weight Mn (Mw / Mn) of 5 or more and 30 or less and a median diameter (D ₅₀ ) on a volume basis of 10 nm or more and 300 nm or less are used. A method for producing a toner for developing an electrostatic charge image.

  In the present invention, it is possible to produce a resin fine particle having a different molecular weight region such that a high molecular weight region and a low molecular weight region coexist, and having a nanometer level by a polymerization method. .

  According to the toner obtained by agglomerating the resin fine particles, when the printing is performed on a large number of sheets exceeding 10,000 continuous sheets, contamination on the surface of the fixing roller and filming on the surface of the photosensitive member are generated. It is now possible to create stable prints without causing problems.

  The inventor has focused on the fact that the toner produced through the process of aggregating a plurality of types of resin fine particles having different molecular weights forms one toner particle as an aggregate of fine particles having different molecular weights. That is, when one toner particle is microscopically captured, regions having different molecular weights depending on the type of resin fine particles, such as a high molecular weight region and a low molecular weight region, or an intermediate molecular weight region, are gathered in a mosaic pattern. It was thought that toner particles were formed. Then, it is considered that the mosaic-like aggregate form of a plurality of types of fine particles having different molecular weights constituting the toner particles is a factor causing the above-mentioned problem. I guess that will be resolved. That is, although the resin fine particles constituting the toner particles are aggregated but do not form a compatible state, the toner particles deteriorate from the interface between the resin fine particles to generate fine powder, causing contamination and filming. Presumed to be.

  Therefore, the present inventor considered to agglomerate resin fine particles having the same feature instead of taking a form of aggregating regions having different molecular weights in a mosaic shape. In other words, it was considered that a resin fine particle having a form in which different molecular weight regions such as a low molecular weight region and a high molecular weight region coexist is produced, and the resin fine particles having different molecular weight regions are aggregated to form a toner. It is.

  Until now, formation of a plurality of different molecular weight regions in one resin fine particle has not been performed. The present inventor added a specific chain transfer agent in the monomer, emulsified and dispersed this, and when emulsion polymerization was performed in this state, a plurality of different molecular weight regions were formed in one resin fine particle. Found that you can. And the said subject was eliminated by using this resin fine particle.

  Hereinafter, the present invention will be described in detail.

  The resin fine particles according to the present invention have a ratio of the weight average molecular weight Mw to the number average molecular weight Mn, that is, Mw / Mn is 5 or more and 30 or less. In the present invention, the term “resin fine particles” is used, which means that the particle size of the particles produced by polymerization is less than 1 μm. More specifically, it means that the volume reference median diameter (D50) described later has a size of 10 nm to 300 nm. A method for measuring the volume-based median diameter (D50) will be described later.

The resin fine particles according to the present invention can be produced, for example, by the following procedure.
(1) First, a monomer containing a chain transfer agent in advance in an aqueous medium is added. The chain transfer agent has a chain transfer constant at 50 ° C. of 10 or more and 40 or less.
(2) Next, a monomer containing a chain transfer agent is dispersed in an aqueous medium so as to form emulsified particles. Specifically, emulsified particles having a median diameter (D ₅₀ ) on a volume basis of 10 nm or more and 300 nm or less are formed.
(3) After adding a polymerization initiator to the liquid in which the emulsified particles are dispersed, polymerization is performed by heating or the like, thereby forming resin fine particles having the above-described configuration. At this time, it is presumed that in the initial stage of polymerization, a low molecular weight region is formed by the action of the chain transfer agent in the monomer, and a high molecular weight region is formed when the chain transfer agent disappears as the polymerization proceeds. By such a mechanism, it is presumed that resin fine particles formed by coexistence of a low molecular weight region and a high molecular weight region are formed.

  The weight average molecular weight and number average molecular weight of the resin constituting the resin fine particles are values obtained by calculation by gel permeation chromatography or gel permeation chromatography.

  Here, molecular weight measurement by gel permeation chromatography (hereinafter also referred to as GPC) will be described.

  Specifically, the following procedure is performed. First, 1 ml of tetrahydrofuran solvent is added to 1 mg of the measurement resin, and the mixture is stirred at room temperature using a magnetic stirrer, etc., and the resin is sufficiently dissolved and filtered through a membrane filter having a pore size of 0.45 to 0.50 μm. To prepare a sample for GPC measurement. Next, after the GPC measurement column is heated and stabilized at 40 ° C., tetrahydrofuran is flowed at a rate of 1 ml per minute, and 100 μL of a measurement sample having a concentration of 1 mg / ml is injected and measured. The measurement column is preferably used in combination with a commercially available polystyrene gel column. For example, Shodex GPC KF-801, 802, 803, 804, 806, 807 made by Showa Denko KK, TSK gel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, TSK guard column made by Tosoh Corporation Combinations can be mentioned. As a detector, a refractive index detector (IR detector) or a UV detector may be used.

  The weight average molecular weight and number average molecular weight of the tetrahydrofuran-soluble component in the resin fine particles are expressed in terms of styrene resin equivalent molecular weight. The molecular weight in terms of styrene resin is determined from a styrene calibration curve. A styrene calibration curve may be prepared by measuring about 10 monodisperse polystyrene standard resins.

  The resin fine particles obtained have a weight average molecular weight (Mw) of 10,000 to 220,000, preferably 7,000 to 180,000.

  In addition, the value of Mw / Mn ratio can be calculated | required by calculation from the value of the weight average molecular weight and number average molecular weight which were obtained above. The Mw / Mn ratio of the resin fine particles is 5 or more and 30 or less, preferably 10 or more and 20 or less.

  The toner obtained by agglomerating resin fine particles having the weight average molecular weight (Mw) in the above range can continuously obtain a high-density toner image even when a large number of sheets are printed.

  Further, the toner obtained by aggregating resin fine particles having an Mw / Mn ratio in the above range can prevent the surface of the fixing roller from being soiled and the filming of the surface of the photosensitive member from occurring even when a large number of sheets are printed.

  If the Mw / Mn ratio of the resin fine particles is too small, the molecular weight distribution becomes sharp and fixing offset tends to occur. If the Mw / Mn ratio of the resin fine particles is too large, the molecular weight distribution becomes broad, and the surface of the fixing roller becomes soiled and sensitive. Filming on the body surface is likely to occur.

  As for the progress of polymerization, the weight average molecular weight is confirmed by the above GPC method at regular intervals (specifically at intervals of 10 minutes).

  From the characteristic curve obtained by GPC measurement, the molecular weight distribution was one peak when the chain transfer agent was expected to be consumed, but the molecular weight distribution was two peaks when the polymerization was completed. Although it cannot be confirmed by one resin fine particle, it is estimated that a low molecular region and a high molecular region are formed in one resin fine particle.

  FIG. 1 is a graph showing an example of changes in the molecular weight region due to the progress of the polymerization reaction.

  In FIG. 1, (a) shows a molecular weight distribution curve at the time when polymerization is expected and the chain transfer agent is expected to be consumed. (B) shows the molecular weight distribution when the polymerization is completed.

The median diameter (D ₅₀ ) of the resin fine particles on the volume basis is 10 nm to 300 nm, preferably 30 nm to 200 nm.

The median diameter (D ₅₀ ) on the volume basis of the resin fine particles is a value obtained by measurement by a dynamic light scattering method using a known “Microtrack UPA-150 (manufactured by Nikkiso Co., Ltd.)”.

  Specifically, the following procedure is performed. First, a few drops of measurement resin fine particles in a 50 ml measuring cylinder are added dropwise, 25 ml of pure water is added, and dispersed for 3 minutes using an ultrasonic cleaner “US-1 (manufactured by Asone)” to prepare measurement materials. To do. Next, 3 ml of the measurement data is put into the cell of “Microtrack UPA-150”, and it is confirmed that the value of SampleLoading is in the range of 0.1-100. And it measures on the following measurement conditions.

Measurement conditions Transparency (transparency): Yes
RefractiveIndex (refractive index): 1.59
Particle Density (particle specific gravity): 1.05 gm / cm ³
Spherical Particles (spherical particles): Yes
Solvent conditions RefractiveIndex (refractive index): 1.33
Viscosity (Viscosity): High (temp) 0.797 × 10 ⁻³ Pa · s
Low (temp) 1.002 × 10 ⁻³ Pa · s
When a toner is prepared by agglomerating the resin fine particles of the present invention, if the median diameter (D ₅₀ ) of the resin fine particles on the volume basis is within the above range, the resin fine particles agglomerate well and a large number of sheets are printed. However, there is no contamination on the surface of the fixing roller, no toner filming occurs, and a toner having a volume-based median diameter (D ₅₀ ) of 5 to 9 μm can be obtained. be able to.

If the median diameter (D ₅₀ ) on the volume basis of the resin fine particles is too small, the strength of the toner obtained by agglomeration becomes weak, and crushing tends to occur in the developing device during printing of a large number of sheets. On the other hand, if the median diameter (D ₅₀ ) on the volume basis of the resin fine particles is too large, aggregation of the resin fine particles does not proceed well at the time of toner formation, and it is difficult to obtain a toner having a uniform shape.

  Next, an example of a method for producing resin fine particles will be described.

The resin fine particles are produced through the following steps.
(1) A step of adding a monomer and a chain transfer agent to an aqueous medium containing a surfactant,
(2) Step of preparing a dispersion of emulsified particles having a monomer and a chain transfer agent by applying mechanical energy to the resulting liquid (3) The emulsified particle dispersion is represented by hydrogen peroxide. After the polymerization initiator is added and heated, the polymerization reaction is performed, and the polymer is rapidly polymerized by the action of the chain transfer agent to form a low molecular weight region, and after the chain transfer agent is used to form the low molecular weight region, Polymerization process in which polymerization is continued by further heating and a high molecular weight region is formed. The type and amount of monomer, the type and amount of chain transfer agent, and the polymerization conditions are the target values of the Mw / Mn ratio of the resulting resin fine particles. Adjust so that

The dispersion diameter of the emulsified particles is adjusted so that the median diameter (D ₅₀ ) on the volume basis of the obtained resin fine particles becomes the target.

  The dispersion diameter of the emulsified particles is preferably adjusted by an emulsifying device for emulsification, dispersion conditions (rotor rotation speed, screen rotation speed) and stirring time. Specific examples of the emulsifying device include a mechanical disperser “CLEAMIX (manufactured by M Technique)” having a circulation path.

(monomer)
Examples of the monomer (polymerizable monomer) used in the present invention include a polymerizable monomer having a carboxyl group and a polymerizable monomer used in combination with the polymerizable monomer having a carboxyl group. .

  Specifically, as a polymerizable monomer having a carboxyl group, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n methacrylate -Octyl, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, methacrylic acid ester derivatives such as dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, N-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, acrylate Such as Le, acrylic acid ester derivatives, acrylonitrile, methacrylonitrile, acrylic acid or methacrylic acid derivatives such as acrylamide.

  Moreover, as a polymerizable monomer used in combination with a polymerizable monomer having a carboxyl group, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p -Ethyl styrene, 2,4-dimethyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn- Styrene or styrene derivatives such as dodecylstyrene, olefins such as ethylene, propylene and isobutylene, vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinyl methyl Ketone, vinyl ethyl ketone, vinyl hex Vinyl ketones such as ketones, N- vinylcarbazole, N- vinyl indole, N- vinyl compounds such as N- vinylpyrrolidone, vinyl naphthalene, and vinyl compounds such as vinyl pyridine.

  Further, it is more preferable to use a combination of monomers having an ionic dissociation group as the polymerizable monomer constituting the resin. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, a phosphoric acid group as a constituent group of the monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumar Examples include acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, and acid phosphooxyethyl methacrylate.

  Furthermore, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, n-butyl acrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol di Polyfunctional vinyls such as acrylate can be used to form a resin having a crosslinked structure.

(Chain transfer agent)
Here, the chain transfer constant refers to the ratio of the rate constant of chain transfer and the rate constant of growth reaction in radical polymerization. The chain transfer constant is defined by the following formula.

(In the reaction formula, Cx is a chain transfer constant.
ktr, x is the chain transfer reaction rate constant
ki is the reaction rate constant at the start of the chain reaction
kp is the growth reaction rate constant
Pn · is a polymer radical with n chain lengths (n = 1, 2, 3,...)
RX is a chain transfer agent
M is a monomer
X. represents a chain transfer radical)
As shown below, the chain transfer constant can also be expressed by the ratio (decrease difference) of the difference between the chain transfer agent and the monomer, and in this case, it is calculated from the following formula. In addition, the value of the chain transfer constant obtained by the following formula is the same value as the chain transfer constant calculated by the above formula.

Cx = dlog [RSH] / dlog [M]
(In the formula, RSH represents the residual concentration of the chain transfer agent, M represents the residual concentration of the monomer, and Cx represents the chain transfer constant)
The chain transfer constant in the present invention is a chain transfer constant when the polymerizable monomer is styrene (50 ° C.).

  Actually, as the chain transfer constant, a literature value (for example, POLYMER HANDBO0K) or a value provided by a manufacturer selling a chain transfer agent can be used.

  However, when there is no literature value, it can also be calculated by experiment. As a method, a chain transfer agent concentration including 0 points is taken at 4 points or more, and in the presence of each concentration of chain transfer agent, an initiator and AIBN (azobisisobutyronitrile) are used, and the bulk of styrene at 60 ° C. Polymerize.

  The reduction amount of the chain transfer agent at this time is determined by a carrier column: HR-1, the monomer addition rate and the molecular weight of the polymer are determined by GPC, and the chain transfer constant is calculated.

  The chain transfer agent used in the present invention preferably has a chain transfer constant at 50 ° C. of 10 or more and 40 or less.

  Use of a chain transfer agent having a chain transfer constant of 10 or more and 40 or less is effective for producing resin fine particles having a desired weight average molecular weight (Mw) and number average molecular weight (Mn) ratio, that is, Mw / Mn ratio. Act on.

  The chain transfer agent used in the present invention is not particularly limited as long as the chain transfer constant is 10 or more and 40 or less. For example, n-butyl mercaptan, n-amyl mercaptan, n-hexyl mercaptan, n-heptyl. N-alkyl mercaptans such as mercaptan, n-octyl mercaptan, n-noryl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, n-stearyl mercaptan, isooctyl 3-mercaptopropionate, ethyl 3-mercaptopropionate, 3-mercapto Propyl propionate, butyl 3-mercaptopropionate, t-butyl 3-mercaptopropionate, 2-ethylhexyl 3-mercaptopropionate, octyl 3-mercaptopropionate, decyl 3-mercaptopropionate 2-methyl-3-mercaptopropionic acid esters such as mercaptopropionic octyl or the like is used.

  For example, the chain transfer constant of n-octyl mercaptan to styrene (50 ° C.) is 19, the chain transfer constant of n-dodecyl mercaptan is 13, the chain transfer constant of n-butyl mercaptan is 22, and the chain transfer constant of n-butyl mercaptan is The chain transfer constant for butyl 22,3-mercaptopropionate is 14, the chain transfer constant for 2-ethylhexyl 3-mercaptopropionate is 14, and the chain transfer constant for octyl 3-mercaptopropionate is 22.

  The addition amount of the chain transfer agent is preferably 0.5 to 5.0% by mass with respect to the monomer.

(Polymerization initiator)
In the present invention, it is possible to use a persulfate such as potassium persulfate or ammonium persulfate or an inorganic peroxide such as hydrogen peroxide as a polymerization initiator used for the polymerization of the polymerizable monomer. Among these inorganic peroxides, hydrogen peroxide is preferable.

  It is also possible to use organic polymerization initiators such as azobisaminodipropane acetate, azobiscyanovaleric acid and its salts.

  As for the addition amount of a polymerization initiator, 0.1-10.0 mass% is preferable with respect to a monomer.

  The toner according to the present invention is obtained using the resin fine particles, and is preferably manufactured through a process of aggregating the resin fine particles.

An example of a method for producing toner through the step of aggregating the resin fine particles will be described in detail.
(1) An aggregating step for aggregating toner particle constituent materials such as the resin fine particles and colorant particles in an aqueous medium to form a toner particle intermediate serving as a toner base (hereinafter referred to as a step of aggregating resin fine particles).
(2) Shape control step (3) for controlling the shape while completing the fusion of the materials constituting the toner particle intermediate by heating and stirring following the step of agglomerating the resin fine particles. Solid-liquid separation from the medium and solid-liquid separation / washing step for cleaning the surface of the toner particle intermediate (4) Drying step (5) for drying the toner particle intermediate subjected to the solid-liquid separation and washing step ) It has an external additive processing step for making a toner usable for image formation by adding an external additive to the dried toner particle intermediate.

Hereinafter, each step will be specifically described.
(1) Step of aggregating resin fine particles This step corresponds to the “step of aggregating resin fine particles in an aqueous medium to grow particles” in the present invention.

  In this step, the resin fine particles generated in the polymerization step are aggregated with a toner particle constituent material such as a colorant particle, whereby a toner particle intermediate (before a function as a toner is imparted by a final treatment such as an external additive treatment). Particles, also referred to as toner matrix and colored particles). In this step, agglomeration (fusion) is also performed in which the aggregated particles are firmly bonded together by an action such as heat.

  It is preferable that the fusion or fusion of the resin fine particles and the colorant proceed together with the aggregation. In addition, after the aggregation is completed, it may be fused at a stretch by means such as heating.

  Specifically, by adding a divalent or trivalent salt into the aqueous medium, the electrostatic repulsion between particles such as resin fine particles and colorant particles is alleviated, so that aggregation is possible. These particles aggregate and grow to form a toner particle intermediate. The agglomerated particles are fused by being bonded by receiving an action such as heat. In this way, the toner particle intermediate is formed and grown.

  The step of aggregating the resin fine particles will be further described. In the step of aggregating the resin fine particles, as described above, the resin fine particles and colorant particles generated in the polymerization step are agglomerated and the particles are fused in a temperature environment equal to or higher than the glass transition temperature of the resin fine particles. is there.

  Particle aggregation is performed by mixing a resin particle dispersion or a colorant particle dispersion below the glass transition temperature of the resin particles, and simultaneously fusing (fused) the aggregated particles by increasing the temperature while the particles are aggregated. There is a method of aggregating particles. According to this method, since the fusion can proceed while growing the particles, there is an advantage that the particle shape and the particle size distribution can be easily controlled.

  From this point of view, in the step of agglomerating resin fine particles, agglomeration and fusion (fusion) are advanced in parallel to grow to the desired particle size, and heating is continued to control the particle shape as necessary. It is preferable to use a so-called “salting out / fusion method”.

  The “aqueous medium” in the present invention refers to a material whose main component (50% by mass or more) is water. Examples of components other than water include water-soluble organic solvents such as methanol, ethanol, isopropanol, butanol, and acetone.

  Aggregation of particles is promoted by adding a metal salt such as a divalent salt. Examples of the metal salt that promotes aggregation include monovalent alkali metal salts such as sodium, potassium, and lithium, divalent metal salts such as calcium, magnesium, manganese, and copper, and trivalent metal salts such as aluminum and iron. Etc. Specific examples include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, and manganese sulfate. These salts may be used alone or in combination of two or more.

  Among these metal salts, a divalent metal salt is particularly preferable because aggregation can be advanced with a small addition amount.

  The addition amount of these metal salts is preferably added so that the concentration of the metal salt is equal to or higher than the critical aggregation concentration in the aqueous medium, specifically, 1.2 times the critical aggregation concentration or more, preferably It is preferable to add 1.5 times or more. Here, the “critical aggregation concentration” is an index relating to the stability of the aqueous dispersion. The critical aggregation concentration can be calculated in detail, for example, by the technique described in Seizo Okamura et al., “Polymer Chemistry, Vol 17, 601 (1960) (edited by the Society of Polymer Science)”. Also, a desired salt is added to the target dispersion for aggregation at different concentrations, the ζ (zeta) potential of the dispersion for aggregation is measured, and the salt concentration at which this value changes is calculated as the critical aggregation concentration. It is also possible.

Further, in the step of aggregating resin fine particles, it is possible to agglomerate toner particle constituent materials such as wax, fixing aid, charge control agent and the like together with resin fine particles and colorant particles.
(2) Shape Control Step In the toner manufacturing method according to the present invention, the shape of the toner particle intermediate (toner base material) is controlled by continuing heating and stirring following the step of aggregating the resin fine particles. That is, by increasing the heating and stirring time, it is possible to control the shape of the toner particle intermediate (toner base) to be nearly spherical.
(3) Solid-liquid separation / washing step In the solid-liquid separation / washing step, the toner particle intermediate (toner base) is removed from the dispersion of the toner-particle intermediate (toner base) cooled to a predetermined temperature in the above step. Solid-liquid separation treatment for solid-liquid separation, and surfactants and salting-out agents from solid-liquid separated toner cake (a lump of agglomerated toner particle intermediate (toner base material) in a wet state) A cleaning process for removing unnecessary materials is performed.

  In the washing treatment, the filtrate is washed with water until the electric conductivity of the filtrate becomes 15 μS / cm or less.

Here, the solid-liquid separation and washing methods are not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a method using a filter press or the like.
(4) Drying step The drying step is a step of drying the toner particle intermediate subjected to the cleaning treatment. In the drying process, the drying process is usually performed in the state of a toner cake. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like. The water content of the dried toner particle intermediate is preferably 5% by mass or less, and more preferably 2% by mass or less. In addition, when the toner particle intermediates (toner base materials) subjected to the drying treatment are weakly aggregated due to the attractive force between the particles, the aggregate may be crushed. Here, as the crushing treatment device, a mechanical crushing device such as a jet mill, a Henschel mixer, a coffee mill, a food processor, or the like can be used.
(5) External Addition Processing Step This step is a step of preparing a toner that can be used for image formation by mixing an external additive with the dried toner particle intermediate (toner base).

  As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

  Next, materials (raw materials) used in the present invention will be described.

(Resin fine particles)
As the resin fine particles, the resin fine particles of the present invention described above are used.

(Coloring agent)
As the colorant, known ones can be used, and specific examples include the following colorants.

  Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

  Examples of the colorant for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48; 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the colorant for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of the colorant for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15; 2, C.I. I. Pigment blue 15; 3, C.I. I. Pigment blue 15; 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. And CI Pigment Green 7. The colorant is preferably used by mixing at a ratio of 1 to 15 parts by mass with respect to 100 parts by mass of the binder resin.

(wax)
A known compound can be used for the wax used in the present invention.

  As such, for example, polyolefin wax such as polyethylene wax and polypropylene wax, long chain hydrocarbon wax such as paraffin wax and sazol wax, dialkyl ketone wax such as distearyl ketone, carnauba wax, montan wax, Trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol tetrastearate, pentaerythritol diacetate dibehenate, glycerine tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitic acid , Ester waxes such as distearyl maleate, amide waxes such as ethylenediamine behenyl amide, trimellitic acid tristearyl amide, etc. It is.

  The amount of wax contained in the toner is preferably 1 to 20% by mass, and more preferably 3 to 15% by mass with respect to the total toner.

(Charge control agent)
A charge control agent can be added to the toner of the present invention as necessary. A known compound can be used as the charge control agent.

(External additive)
Examples of inorganic particles that can be used as an external additive include conventionally known particles. Specifically, silica fine particles, titania fine particles, alumina fine particles, and complex oxides thereof can be preferably used. These inorganic particles are preferably hydrophobic.

  Examples of the organic fine particles that can be used as the external additive include spherical fine particles having a number average primary particle diameter of about 10 to 2000 nm. Examples of the constituent material of the organic fine particles include polystyrene, polymethyl methacrylate, styrene-methyl methacrylate copolymer, and the like.

The median diameter (D ₅₀ ) of the toner according to the present invention on the volume basis is preferably 3 to 9 μm from the viewpoints of image quality, developability (image density), and fixability.

The coefficient of variation in the median diameter (D ₅₀ ) of the toner based on the volume and the particle size distribution based on the volume were connected to a multisizer 3 (manufactured by Beckman Coulter) and a computer system for data processing (manufactured by Beckman Coulter). Measurement and calculation can be performed by using an apparatus.

  As a measurement procedure, 0.02 g of toner is used in 20 ml of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing the toner). Then, ultrasonic dispersion is performed for 1 minute to prepare a toner dispersion. This toner dispersion is poured into a beaker containing ISOTON II (manufactured by Beckman Coulter, Inc.) in a sample stand with a pipette until a measurement concentration of 8% by mass, and the measuring machine count is set to 2500 and measured. . Note that the aperture size of the multisizer 3 is 50 μm.

  The toner according to the present invention can be used as a one-component developer or a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. can do.

  Further, it can be mixed with a carrier and used as a two-component developer. As the carrier, conventionally known magnetic particles such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Ferrite particles are particularly preferable. The particle diameter of the carrier is preferably 20 to 100 μm, and more preferably 25 to 80 μm.

  Examples of the image forming apparatus that can use the toner according to the present invention include a monochrome image forming apparatus that forms an image with a single color toner, a color image forming apparatus that sequentially transfers a toner image on a photosensitive member to an intermediate transfer member, And a tandem color image forming apparatus in which a plurality of photoconductors are arranged in series on an intermediate transfer member.

  The toner according to the present invention is effective when used for tandem color image formation.

  FIG. 2 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus in which the toner according to the present invention can be used.

  In FIG. 2, 1Y, 1M, 1C and 1K are photosensitive members, 4Y, 4M, 4C and 4K are developing means, 5Y, 5M, 5C and 5K are primary transfer rollers as primary transfer means, and 5A is a secondary transfer roller. Secondary transfer rollers as means, 6Y, 6M, 6C and 6K are cleaning means, 7 is an intermediate transfer body unit, 24 is a heat roller type fixing device, and 70 is an intermediate transfer body.

  This image forming apparatus is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an endless belt-shaped intermediate transfer body unit 7 as a transfer unit, and a recording member P. An endless belt-shaped sheet feeding / conveying means 21 and a heat roller type fixing device 24 as a fixing means. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  As one of the different color toner images formed on each photoconductor, an image forming unit 10Y that forms a yellow image includes a drum-shaped photoconductor 1Y as a first photoconductor, and a periphery of the photoconductor 1Y. A charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a primary transfer roller 5Y as a primary transfer unit, and a cleaning unit 6Y. An image forming unit 10M that forms a magenta image as another different color toner image is disposed around a drum-shaped photoconductor 1M as a first photoconductor, and the photoconductor 1M. A charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, and a cleaning unit 6M. In addition, an image forming unit 10C that forms a cyan image as one of other different color toner images is disposed around the photoconductor 1C as a drum-type photoconductor 1C as a first photoconductor. The charging unit 2C, the exposure unit 3C, the developing unit 4C, a primary transfer roller 5C as a primary transfer unit, and a cleaning unit 6C are provided. Further, an image forming unit 10K that forms a black image as one of other different color toner images is disposed around a drum-shaped photosensitive member 1K as a first photosensitive member, and the photosensitive member 1K. It has a charging unit 2K, an exposure unit 3K, a developing unit 4K, a primary transfer roller 5K as a primary transfer unit, and a cleaning unit 6K.

  The endless belt-shaped intermediate transfer body unit 7 has an endless belt-shaped intermediate transfer body 70 as an intermediate transfer endless belt-shaped second image carrier that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred onto the rotating endless belt-shaped intermediate transfer body 70 by the primary transfer rollers 5Y, 5M, 5C, and 5K, and is combined. A colored image is formed. A recording member P such as a sheet as a transfer material accommodated in the sheet feeding cassette 20 is fed by the sheet feeding / conveying means 21, passes through a plurality of intermediate rollers 22 A, 22 B, 22 C, 22 D, and a registration roller 23, and is secondary. A color image is transferred onto the recording member P at a time by being conveyed to a secondary transfer roller 5A as a transfer means. The recording member P to which the color image has been transferred is fixed by a heat roller type fixing device 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus.

  On the other hand, after the color image is transferred to the recording member P by the secondary transfer roller 5A, the residual toner is removed by the cleaning means 6A from the endless belt-shaped intermediate transfer body 70 in which the recording member P is separated by curvature.

  During the image forming process, the primary transfer roller 5K is always in pressure contact with the photoreceptor 1K. The other primary transfer rollers 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5A comes into pressure contact with the endless belt-shaped intermediate transfer body 70 only when the recording member P passes through the secondary transfer roller 5A and secondary transfer is performed.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10K, and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is arranged on the left side of the photoreceptors 1Y, 1M, 1C, and 1K in the figure. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, and 76, primary transfer rollers 5Y, 5M, 5C, and 5K, and a cleaning unit. 6A.

  The image forming units 10Y, 10M, 10C, and 10K and the endless belt-shaped intermediate transfer body unit 7 are integrally pulled out from the main body A by the drawer operation of the housing 8.

  In this way, toner images are formed on the photoreceptors 1Y, 1M, 1C, and 1K by charging, exposure, and development, and the toner images of the respective colors are superimposed on the endless belt-shaped intermediate transfer body 70, and are collectively applied to the recording member P. The image is transferred and fixed by a heat roller type fixing device 24 by pressing and heating. The photoreceptors 1Y, 1M, 1C, and 1K after transferring the toner image to the recording member P are cleaned with the cleaning device 6A to remove the toner remaining on the photoreceptor, and then the above-described charging, exposure, and development cycle. The next image formation is performed.

  The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited to these examples.

<Preparation of resin fine particles>
Resin fine particles were prepared as follows.

<Preparation of dispersion of resin fine particles 1>
Styrene 84.1 parts by weight n-butyl acrylate 43.4 parts by weight Methacrylic acid 11.4 parts by weight n-dodecyl mercaptan 3.79 parts by weight is put in a stainless steel kettle equipped with a stirrer, 100 parts by mass of pentaerythritol tetrabehenate was added, heated to 90 ° C. and dissolved to prepare a monomer mixture.

  Meanwhile, a surfactant solution in which 2 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate was dissolved in 1350 parts by mass of ion-exchanged water was heated to 70 ° C., and the monomer mixture was added and mixed. Using a mechanical disperser “CLEAMIX W motion (manufactured by M Technique)” having a circulation path, dispersion was performed for 30 minutes under the processing conditions of a rotor of 21000 rpm and a screen of 5700 rpm to prepare a dispersion of emulsified particles.

  Next, a polymerization initiator solution in which 7.5 parts by mass of potassium persulfate is dissolved in 150 parts by mass of ion-exchanged water is added to the dispersion of the emulsified particles, and the system is heated and stirred at 80 ° C. for 2.0 hours. Polymerization was performed to prepare a dispersion containing resin fine particles. This dispersion of resin fine particles is referred to as “dispersion of resin fine particles 1”.

The median diameter (D ₅₀ ) of the resin fine particles in the “dispersion of resin fine particles 1” on a volume basis was measured by the above method to be 100 nm.

Moreover, when a part of the “dispersion of resin fine particles 1” was dried to isolate the resin fine particles, and the weight average molecular weight and number average molecular weight were measured by the above method, the weight average molecular weight was 15000, and the number average molecular weight was 3000. (Mw / Mn = 5)
<Preparation of dispersion of resin fine particles 2>
A “dispersion of resin fine particles 2” was produced in the same manner except that n-dodecylcaptan used in the production of “dispersion of resin fine particles 1” was changed to n-octyl mercaptan.

A volume-based median diameter of resin fine (D ₅₀₎ was 150nm was measured by the aforementioned method. Moreover, the weight average molecular weight was 45000 and the number average molecular weight was 3000. (Mw / Mn = 15)
<Preparation of dispersion of resin fine particles 3>
A “dispersion of resin fine particles 3” was prepared in the same manner except that n-dodecyl mercaptan used in the production of “dispersion of resin fine particles 1” was changed to n-stearyl mercaptan.

A volume-based median diameter of resin fine (D ₅₀₎ was 150nm was measured by the aforementioned method. Moreover, the weight average molecular weight was 90000 and the number average molecular weight was 3000. (Mw / Mn = 30)
<Preparation of dispersion of resin fine particles 4>
In the production of “dispersion of resin fine particles 1”, a mechanical dispersion machine “CLEARMIX (manufactured by M Technique Co., Ltd.)” having a circulation path was used and dispersed for 30 minutes under the processing conditions of rotor 21000 rpm and screen 5700 rpm. A “dispersion of resin fine particles 4” was prepared in the same manner except that the dispersion was changed to 90 minutes under the processing conditions of a rotor of 21000 rpm and a screen of 9000 rpm.

The median diameter (D ₅₀ ) of the resin fine particles on a volume basis was 10 nm. Moreover, the weight average molecular weight was 15000 and the number average molecular weight was 3000. (Mw / Mn = 5)
<Preparation of dispersion of resin fine particles 5>
In the production of “dispersion of resin fine particles 3”, a mechanical dispersion machine “CLEARMIX (manufactured by M Technique Co., Ltd.)” having a circulation path was used and dispersed for 30 minutes under the processing conditions of rotor 21000 rpm and screen 5700 rpm. A “dispersion of resin fine particles 5” was prepared in the same manner except that the dispersion was changed for 20 minutes under the processing conditions of the rotor 15000 rpm and the screen 5700 rpm.

The median diameter (D ₅₀ ) of the resin fine particles on a volume basis was 300 nm. Moreover, the weight average molecular weight was 90000 and the number average molecular weight was 3000. (Mw / Mn = 30)
<Preparation of dispersion of resin fine particles 6>
A “dispersion of resin fine particles 6” was prepared in the same manner except that n-dodecyl mercaptan used in the preparation of “dispersion of resin fine particles 1” was changed to α-terpinene.

A volume-based median diameter of resin fine (D ₅₀₎ was 150nm was measured by the aforementioned method. Moreover, the weight average molecular weight was 18000 and the number average molecular weight was 6000. (Mw / Mn = 3)
<Preparation of dispersion of resin fine particles 7>
A “dispersion of resin fine particles 7” was prepared in the same manner except that n-dodecyl mercaptan used in the preparation of “dispersion of resin fine particles 1” was changed to p-toluoyl disulfide.

The median diameter (D ₅₀ ) of the resin fine particles on the volume basis was measured by the above method to be 150 nm. Moreover, the weight average molecular weight was 222000 and the number average molecular weight was 6000. (Mw / Mn = 37)
Production of “dispersion of resin fine particles 8” In the production of “dispersion of resin fine particles 2”, a mechanical disperser “CLEAMIX (manufactured by M Technique Co., Ltd.)” having a circulation path was used, with a rotor of 21000 rpm and a screen of 5700 rpm. A “dispersion of resin fine particles 8” was prepared in the same manner except that the dispersion for 30 minutes under the treatment conditions was changed to dispersion for 120 minutes under the treatment conditions of rotor 21,000 rpm and screen 10000 rpm.

The median diameter (D ₅₀ ) of the resin fine particles on the volume basis was 8 nm. Moreover, the weight average molecular weight was 45000 and the number average molecular weight was 3000. (Mw / Mn = 15)
Production of “dispersion of resin fine particles 9” In the production of “dispersion of resin fine particles 2”, a mechanical disperser “CLEAMIX (manufactured by M Technique Co., Ltd.)” having a circulation path was used, with a rotor of 21000 rpm and a screen of 5700 rpm. A “resin fine particle 9 dispersion” was prepared in the same manner except that the dispersion for 30 minutes under the treatment conditions was changed to the dispersion for 10 minutes under the treatment conditions of the rotor 13000 rpm and the screen 5700 rpm.

The median diameter (D ₅₀ ) of the resin fine particles on the volume basis was 330 nm. Moreover, the weight average molecular weight was 45000 and the number average molecular weight was 3000. (Mw / Mn = 15)
<Preparation of dispersion of resin fine particles 10>
Stainless steel kettle equipped with a stirrer and a mixed solution containing a surfactant prepared by dissolving 100 parts by mass of pentaerythritol tetrabehenate and 2 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate in 1350 parts by mass of ion-exchanged water The solution was heated to 70 ° C. with stirring, and the following monomer mixture was added dropwise over 2 hours. Then, it superposed | polymerized by heating and stirring at 80 degreeC for 2.0 hours, and produced the dispersion liquid containing resin fine particles. This dispersion of resin fine particles is referred to as “dispersion of resin fine particles 10”.

Monomer mixture liquid Styrene 99.4 parts by mass n-butyl acrylate 28.7 parts by mass Methacrylic acid 14.9 parts by mass n-octyl mercaptan 2.9 parts by mass in a stainless steel kettle equipped with a stirrer A monomer mixture was prepared by dissolving the mixture.

The median diameter (D ₅₀ ) of the resin fine particles in the “dispersion of resin fine particles 10” on a volume basis was measured by the above-mentioned method and found to be 150 nm.

Further, when a part of the “dispersion of resin fine particles 10” was dried to isolate the resin fine particles, and the weight average molecular weight and number average molecular weight were measured by the above method, the weight average molecular weight was 15000, and the number average molecular weight was 5000. (Mw / Mn = 3)
<Preparation of dispersion of resin fine particles 11>
“Resin fine particles” were similarly prepared except that the amount of n-octylcaptan used in the production of “dispersion of resin fine particles 10” was changed from 2.89 parts by mass to 1.45 parts by mass (0.5 times). 11 dispersion ".

A volume-based median diameter of resin fine (D ₅₀₎ was 150nm was measured by the aforementioned method. Moreover, the weight average molecular weight was 6000 and the number average molecular weight was 2000. (Mw / Mn = 3)
Table 1 shows the weight average molecular weight (Mw), number average molecular weight (Mn), Mw / Mn ratio, and median diameter (D ₅₀ ) based on volume of the prepared resin fine particles.

From the results shown in Table 1, it can be seen that the resin fine particles 1 to 5 satisfy the Mw / Mn ratio defined in the present invention and the median diameter (D ₅₀ ) on the volume basis. On the other hand, it can be seen that the resin fine particles 6 to 11 do not satisfy either the Mw / Mn ratio defined in the present invention or the median diameter (D ₅₀ ) on the volume basis.

<Production of toner>
A toner was prepared as follows.

<Preparation of Colorant Particle Dispersion Bk>
90 parts by mass of sodium dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water and dissolved by stirring. While stirring this liquid, 420 parts by mass of “Regal 330R (Cabot)” as a black colorant is gradually added, and then using a mechanical disperser “Clearmix (M Technique)”. By performing a dispersion treatment, a colorant particle dispersion was prepared. This is designated as “colorant particle dispersion Bk”. The particle diameter of the colorant particles in the “colorant particle dispersion Bk” was 110 nm when measured using an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)”.

<Preparation of Colorant Particle Dispersion C>
The “colorant” was similarly changed except that the black colorant “Regal 330R” used in the preparation of the colorant particle dispersion Bk was changed to a cyan colorant “Lionol Blue 7334E-P-FD” (manufactured by Toyo Ink Co., Ltd.). A particle dispersion C "was prepared. The particle diameter of the colorant particles in the “colorant particle dispersion C” was 210 nm as measured using an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)”.

<Preparation of Colorant Particle Dispersion M>
“Colorant particle dispersion M” was similarly changed except that the black colorant “Regal 330R” used in the preparation of the colorant particle dispersion Bk was changed to the magenta colorant “CI Pigment Red 122”. Prepared. The particle diameter of the colorant particles in the “colorant particle dispersion M” was 190 nm when measured using an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)”.

<Preparation of Colorant Particle Dispersion Y>
“Colorant particle dispersion M” was similarly used except that the black colorant “Regal 330R” used in the preparation of the colorant particle dispersion Bk was changed to “CI Pigment Yellow 74” as the yellow colorant. Was prepared. The particle diameter of the colorant particles in the “colorant particle dispersion M” was 200 nm as measured using an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)”.

<Preparation of Toner Bk1>
392 parts by mass of “dispersion of resin fine particles 1” (in terms of solid content), 1100 parts by mass of ion-exchanged water, and 200 parts by mass of “colorant particle dispersion Bk” were mixed with a thermometer, a cooling tube, a nitrogen introducing device, and stirring. It put into the separable flask which provided the apparatus. Further, a 5N aqueous sodium hydroxide solution (25% by mass) was added while maintaining the temperature in the system at 30 ° C., and the pH was adjusted to 10.

Next, an aqueous solution in which 60 parts by mass of magnesium chloride hexahydrate was dissolved in 60 parts by mass of ion-exchanged water was added. After holding for 3 minutes, the temperature was raised and the system was heated to 80 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 80 ° C. In this state, the particle size of the associated particles was measured with a particle size distribution measuring apparatus “Multisizer 3 (manufactured by Beckman Coulter)”, and when the median diameter (D ₅₀ ) on the volume basis became 6.0 μm, An aqueous solution in which 40 parts by mass of sodium was dissolved in 160 parts by mass of ion-exchanged water was added to stop particle growth. Further, as a ripening step, the liquid temperature was 80 ° C. for 1 hour with heating and stirring to advance the fusion between the particles, and “colored particles Bk1” were produced.

  Next, the dispersion of “colored particles Bk1” is subjected to solid-liquid separation with a basket-type centrifuge “MARK III type (model number 60 × 40) (manufactured by Matsumoto Opportunity Manufacturing Co., Ltd.)” to wet “colored particles Bk1”. A cake was formed. Thereafter, washing and solid-liquid separation of “colored particles Bk1” were repeated until the electric conductivity of the filtrate reached 15 μS / cm or less.

  The final wet cake was transferred to an airflow dryer “flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.)”, and “colored particles Bk1” were dried until the water content became 0.5 mass%. The drying process was performed by blowing an air current of 40 ° C. and 20% RH.

  1% by mass of hydrophobic silica having a number average primary particle size of 12 nm and a hydrophobization degree of 68 is used for “colored particles Bk1” after the drying treatment, using a “Henschel mixer (manufactured by Mitsui Miike Chemical Co., Ltd.)”. Further, hydrophobic titanium oxide having a number average primary particle size of 80 nm and a hydrophobization degree of 63 was added so as to be 0.3% by mass to prepare “Toner Bk1”.

The median diameter (D ₅₀ ) of the obtained “Toner Bk1” on a volume basis was 6.0 μm.

<Preparation of Toners Bk2 to Bk9>
“Toners Bk2 to Bk9” were prepared in the same manner except that the dispersion of resin fine particles 1 used in the production of “Toner Bk1” was changed to “Dispersion of resin fine particles 2 to 9”.

<Preparation of Toner Bk10>
392 parts by mass (solid content conversion) of the resin fine particle 1 dispersion used in the production of “Toner Bk1” is 196 parts by mass of “resin fine particle 10” (in terms of solid content) and 196 parts by mass of “dispersion of resin fine particle 11”. “Toner Bk10” was prepared in the same manner except that the solid content was changed.

<Preparation of Toners C1 to C10>
“Toners C1 to C10” were prepared in the same manner except that “Colorant particle dispersion Bk” used in the preparation of “Toners Bk1 to Bk10” was changed to “Colorant particle dispersion C”.

<Preparation of Toners M1 to M10>
“Toners M1 to M10” were similarly prepared except that “Colorant particle dispersion Bk” used in the preparation of “Toners Bk1 to Bk10” was changed to “Colorant particle dispersion M”.

<Preparation of Toners Y1 to Y10>
“Toners Y1 to Y10” were similarly prepared except that “Colorant particle dispersion Bk” used in the preparation of “Toners Bk1 to Bk10” was changed to “Colorant particle dispersion Y”.

<Production of developer>
Each of the “toners Bk1 to Bk10”, “toners C1 to C10”, “toners M1 to M10” and “toners Y1 to Y10” obtained above is coated with a silicone resin and has a volume average particle diameter of 50 μm. Were mixed to prepare “developer” corresponding to each toner having a toner concentration of 6%.

<Evaluation>
<Evaluation equipment>
“Bizhub PRO C500 (manufactured by Konica Minolta Business Technologies)” was used as an image evaluation apparatus for the toner produced above.

<Evaluation methods>
The evaluation was performed for the following items in an environment of normal temperature and normal humidity (20 ° C., 55% RH) by sequentially loading the toner prepared above in the evaluation apparatus.

  The print is an image with a pixel rate of 10% (original image in 6% text image, 2% color portrait photo, 2% solid image (each color is divided into ¼ equal parts)) “J paper (Konica Minolta To "Business Technologies, Inc.)".

  In addition, (double-circle), (circle), and (triangle | delta) pass with no problem practically, and x has a problem practically and fails.

<Evaluation item>
(Fixing roller surface contamination)
After the completion of printing 500,000 sheets, the fixing roller surface contamination was evaluated by visually evaluating the contamination state of the toner on the developing roller surface and the degree of occurrence of fog caused by the developing roller surface contamination on the print after completion of printing 500,000 sheets. .

Evaluation Criteria A: No stain due to toner on the developing roller surface after completion of printing 500,000 sheets, and no fogging due to contamination on the developing roller surface was observed. O: Development roller surface after completion of printing 500,000 sheets Dirt due to toner was slightly seen, but no fogging due to dirt on the developing roller surface was observed. Δ: Dirt due to toner on the developing roller surface after completion of printing 500,000 sheets was seen, and the developing roller surface was stained. Occurrence of fogging due to toner was observed. ×: The surface of the developing roller was very dirty with toner, and printing was stopped before printing 500,000 sheets.

(Photoconductor surface filming)
Photoconductor surface filming is a visual evaluation of the filming state on the surface of the photoconductor after completion of printing 500,000 sheets, and the degree of image density unevenness due to filming on the surface of the photoconductor in the print after completion of printing 500,000 sheets. It was evaluated with.

Evaluation Criteria A: Filming on the surface of the photoconductor after completion of printing 500,000 sheets was not observed, and no image density unevenness due to filming was observed. O: Filming on the surface of the photoconductor after completion of printing 500,000 sheets Image density unevenness due to filming was not observed. Δ: Filming on the surface of the photoconductor after completion of printing 500,000 sheets was observed, and image density unevenness due to filming was also observed. X: Filming on the surface of the photoconductor was so severe that printing was stopped before 500,000 sheets.

(Developer durability)
The durability of the developer was evaluated by the image density from the beginning to the end of printing 500,000 sheets. The image density was measured at 12 points using a reflection densitometer “RD-918 (manufactured by Macbeth)”, and the average value was evaluated as the image density.

Evaluation Criteria A: Image density is 1.35 or more from the initial printing to after printing 500,000 sheets, and the durability of the developer is excellent B: Image density is 1.30 or more from the initial printing to after printing 500,000 sheets The durability of the developer is good. Δ: The image density is 1.20 or more and 1.30 or less from the initial printing to after printing 500,000 sheets. Since it became less than 1.20, which is a practical problem, printing was stopped before 500,000 sheets.

  Table 2 shows the evaluation results.

  From the evaluation results in Table 2, it was confirmed that Examples 1 to 5 showed good results in all the evaluation items and exhibited the effects of the present invention. On the other hand, in Comparative Examples 1 to 7, satisfactory results were not obtained for any of the evaluation items, and it was confirmed that the effects of the present invention were not exhibited.

It is a graph which shows an example of the change of the molecular weight area | region by progress of a polymerization reaction. 1 is a schematic diagram illustrating an example of an image forming apparatus used in an image forming method according to the present invention.

Explanation of symbols

1Y, 1M, 1C, 1K Photoconductors 4Y, 4M, 4C, 4K Developing means 5Y, 5M, 5C, 5K Primary transfer roller as primary transfer means 5A Secondary transfer roller as secondary transfer means 6Y, 6M, 6C, 6K Cleaning means 7 Endless belt-shaped intermediate transfer body unit

Claims (6)

A resin fine particle having a ratio of the weight average molecular weight Mw to the number average molecular weight Mn (Mw / Mn) of 5 or more and 30 or less, and a median diameter (D ₅₀ ) based on volume of 10 nm or more and 300 nm or less. In the method for producing resin fine particles, wherein a composition containing at least a monomer is emulsified and dispersed in an aqueous medium, and the emulsion-dispersed monomer is subjected to emulsion polymerization to produce particles.
A method for producing resin fine particles, comprising adding a chain transfer agent having a chain transfer constant at 50 ° C. of 10 to 40 to the monomer, followed by emulsion polymerization. At least in a method for producing resin fine particles obtained by emulsifying and dispersing a composition containing a monomer in an aqueous medium, and subjecting the emulsified and dispersed monomer to emulsion polymerization.
A ratio of the weight average molecular weight Mw to the number average molecular weight Mn (Mw / Mn) of the resin fine particles is 5 or more and 30 or less, and a median diameter (D ₅₀ ) based on volume is 10 nm or more and 300 nm or less. For producing resin fine particles. At least in the electrostatic image developing toner obtained by aggregating resin fine particles and colored particles,
A toner for developing an electrostatic charge image, comprising the resin fine particles according to claim 1. Production of an electrostatic charge image developing toner comprising at least a step of emulsifying and dispersing a monomer-containing composition in an aqueous medium, a step of emulsion-polymerizing the emulsified and dispersed monomer to produce resin fine particles, and a step of aggregating resin fine particles In the method
An electrostatic charge image developing toner comprising: a resin fine particle obtained by adding a chain transfer agent having a chain transfer constant at 50 ° C. of 10 to 40 to a monomer and emulsion polymerization as the resin fine particle. Production method. An electrostatic charge image developing toner comprising at least a step of emulsifying and dispersing a monomer-containing composition in an aqueous medium, a step of emulsion-polymerizing the emulsion-dispersed monomer to produce resin fine particles, and a step of aggregating the resin fine particles. In the manufacturing method,
As the resin fine particles, resin fine particles having a ratio of the weight average molecular weight Mw to the number average molecular weight Mn (Mw / Mn) of 5 or more and 30 or less and a median diameter (D ₅₀ ) on a volume basis of 10 nm or more and 300 nm or less are used. A method for producing a toner for developing an electrostatic charge image.

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